Sample records for tca cycle flux

  1. Temporal fluxomics reveals oscillations in TCA cycle flux throughout the mammalian cell cycle.

    PubMed

    Ahn, Eunyong; Kumar, Praveen; Mukha, Dzmitry; Tzur, Amit; Shlomi, Tomer

    2017-11-06

    Cellular metabolic demands change throughout the cell cycle. Nevertheless, a characterization of how metabolic fluxes adapt to the changing demands throughout the cell cycle is lacking. Here, we developed a temporal-fluxomics approach to derive a comprehensive and quantitative view of alterations in metabolic fluxes throughout the mammalian cell cycle. This is achieved by combining pulse-chase LC-MS-based isotope tracing in synchronized cell populations with computational deconvolution and metabolic flux modeling. We find that TCA cycle fluxes are rewired as cells progress through the cell cycle with complementary oscillations of glucose versus glutamine-derived fluxes: Oxidation of glucose-derived flux peaks in late G1 phase, while oxidative and reductive glutamine metabolism dominates S phase. These complementary flux oscillations maintain a constant production rate of reducing equivalents and oxidative phosphorylation flux throughout the cell cycle. The shift from glucose to glutamine oxidation in S phase plays an important role in cell cycle progression and cell proliferation. © 2017 The Authors. Published under the terms of the CC BY 4.0 license.

  2. Glutamatergic and GABAergic TCA cycle and neurotransmitter cycling fluxes in different regions of mouse brain.

    PubMed

    Tiwari, Vivek; Ambadipudi, Susmitha; Patel, Anant B

    2013-10-01

    The (13)C nuclear magnetic resonance (NMR) studies together with the infusion of (13)C-labeled substrates in rats and humans have provided important insight into brain energy metabolism. In the present study, we have extended a three-compartment metabolic model in mouse to investigate glutamatergic and GABAergic tricarboxylic acid (TCA) cycle and neurotransmitter cycle fluxes across different regions of the brain. The (13)C turnover of amino acids from [1,6-(13)C2]glucose was monitored ex vivo using (1)H-[(13)C]-NMR spectroscopy. The astroglial glutamate pool size, one of the important parameters of the model, was estimated by a short infusion of [2-(13)C]acetate. The ratio Vcyc/VTCA was calculated from the steady-state acetate experiment. The (13)C turnover curves of [4-(13)C]/[3-(13)C]glutamate, [4-(13)C]glutamine, [2-(13)C]/[3-(13)C]GABA, and [3-(13)C]aspartate from [1,6-(13)C2]glucose were analyzed using a three-compartment metabolic model to estimate the rates of the TCA cycle and neurotransmitter cycle associated with glutamatergic and GABAergic neurons. The glutamatergic TCA cycle rate was found to be highest in the cerebral cortex (0.91 ± 0.05 μmol/g per minute) and least in the hippocampal region (0.64 ± 0.07 μmol/g per minute) of the mouse brain. In contrast, the GABAergic TCA cycle flux was found to be highest in the thalamus-hypothalamus (0.28 ± 0.01 μmol/g per minute) and least in the cerebral cortex (0.24 ± 0.02 μmol/g per minute). These findings indicate that the energetics of excitatory and inhibitory function is distinct across the mouse brain.

  3. The oxidative TCA cycle operates during methanotrophic growth of the Type I methanotroph Methylomicrobium buryatense 5GB1.

    PubMed

    Fu, Yanfen; Li, Yi; Lidstrom, Mary

    2017-07-01

    Methanotrophs are a group of bacteria that use methane as sole carbon and energy source. Type I methanotrophs are gamma-proteobacterial methanotrophs using the ribulose monophosphate cycle (RuMP) cycle for methane assimilation. In order to facilitate metabolic engineering in the industrially promising Type I methanotroph Methylomicrobium buryatense 5GB1, flux analysis of cellular metabolism is needed and 13 C tracer analysis is a foundational tool for such work. This biological system has a single-carbon input and a special network topology that together pose challenges to the current well-established methodology for 13 C tracer analysis using a multi-carbon input such as glucose, and to date, no 13 C tracer analysis of flux in a Type I methanotroph has been reported. In this study, we showed that by monitoring labeling patterns of several key intermediate metabolites in core metabolism, it is possible to quantitate the relative flux ratios for important branch points, such as the malate node. In addition, it is possible to assess the operation of the TCA cycle, which has been thought to be incomplete in Type I methanotrophs. Surprisingly, our analysis provides direct evidence of a complete, oxidative TCA cycle operating in M. buryatense 5GB1 using methane as sole carbon and energy substrate, contributing about 45% of the total flux for de novo malate production. Combined with mutant analysis, this method was able to identify fumA (METBUDRAFT_1453/MBURv2__60244) as the primary fumarase involved in the oxidative TCA cycle, among 2 predicted fumarases, supported by 13 C tracer analysis on both fumA and fumC single knockouts. Interrupting the oxidative TCA cycle leads to a severe growth defect, suggesting that the oxidative TCA cycle functions to not only provide precursors for de novo biomass synthesis, but also to provide reducing power to the system. This information provides new opportunities for metabolic engineering of M. buryatense for the production of

  4. Metabolism: Part II. The Tricarboxylic Acid (TCA), Citric Acid, or Krebs Cycle.

    ERIC Educational Resources Information Center

    Bodner, George M.

    1986-01-01

    Differentiates the tricarboxylic acid (TCA) cycle (or Krebs cycle) from glycolysis, and describes the bridge between the two as being the conversion of pyruvate into acetyl coenzyme A. Discusses the eight steps in the TCA cycle, the results of isotopic labeling experiments, and the net effects of the TCA cycle. (TW)

  5. The emerging role and targetability of the TCA cycle in cancer metabolism.

    PubMed

    Anderson, Nicole M; Mucka, Patrick; Kern, Joseph G; Feng, Hui

    2018-02-01

    The tricarboxylic acid (TCA) cycle is a central route for oxidative phosphorylation in cells, and fulfills their bioenergetic, biosynthetic, and redox balance requirements. Despite early dogma that cancer cells bypass the TCA cycle and primarily utilize aerobic glycolysis, emerging evidence demonstrates that certain cancer cells, especially those with deregulated oncogene and tumor suppressor expression, rely heavily on the TCA cycle for energy production and macromolecule synthesis. As the field progresses, the importance of aberrant TCA cycle function in tumorigenesis and the potentials of applying small molecule inhibitors to perturb the enhanced cycle function for cancer treatment start to evolve. In this review, we summarize current knowledge about the fuels feeding the cycle, effects of oncogenes and tumor suppressors on fuel and cycle usage, common genetic alterations and deregulation of cycle enzymes, and potential therapeutic opportunities for targeting the TCA cycle in cancer cells. With the application of advanced technology and in vivo model organism studies, it is our hope that studies of this previously overlooked biochemical hub will provide fresh insights into cancer metabolism and tumorigenesis, subsequently revealing vulnerabilities for therapeutic interventions in various cancer types.

  6. The Variations of Glycolysis and TCA Cycle Intermediate Levels Grown in Iron and Copper Mediums of Trichoderma harzianum.

    PubMed

    Tavsan, Zehra; Ayar Kayali, Hulya

    2015-05-01

    The efficiency of optimal metabolic function by microorganism depends on various parameters, especially essential metal supplementation. In the present study, the effects of iron and copper metals on metabolism were investigated by determination of glycolysis and tricarboxylic acid (TCA) cycle metabolites' levels with respect to the metal concentrations and incubation period in Trichoderma harzianum. The pyruvate and citrate levels of T. harzianum increased up to 15 mg/L of copper via redirection of carbon flux though glycolysis by suppression of pentose phosphate pathway (PPP). However, the α-ketoglutarate levels decreased at concentration higher than 5 mg/L of copper to overcome damage of oxidative stress. The fumarate levels correlated with the α-ketoglutarate levels because of substrate limitation. Besides, in T. harzianum cells grown in various concentrations of iron-containing medium, the intracellular pyruvate, citrate, and α-ketoglutarate levels showed positive correlation with iron concentration due to modifying of expression of glycolysis and TCA cycle enzymes via a mechanism involving cofactor or allosteric regulation. However, as a result of consuming of prior substrates required for fumarate production, its levels rose up to 10 mg/L.

  7. Succinate links TCA cycle dysfunction to oncogenesis by inhibiting HIF-alpha prolyl hydroxylase.

    PubMed

    Selak, Mary A; Armour, Sean M; MacKenzie, Elaine D; Boulahbel, Houda; Watson, David G; Mansfield, Kyle D; Pan, Yi; Simon, M Celeste; Thompson, Craig B; Gottlieb, Eyal

    2005-01-01

    Several mitochondrial proteins are tumor suppressors. These include succinate dehydrogenase (SDH) and fumarate hydratase, both enzymes of the tricarboxylic acid (TCA) cycle. However, to date, the mechanisms by which defects in the TCA cycle contribute to tumor formation have not been elucidated. Here we describe a mitochondrion-to-cytosol signaling pathway that links mitochondrial dysfunction to oncogenic events: succinate, which accumulates as a result of SDH inhibition, inhibits HIF-alpha prolyl hydroxylases in the cytosol, leading to stabilization and activation of HIF-1alpha. These results suggest a mechanistic link between SDH mutations and HIF-1alpha induction, providing an explanation for the highly vascular tumors that develop in the absence of VHL mutations.

  8. Lipotoxicity in steatohepatitis occurs despite an increase in tricarboxylic acid cycle activity

    PubMed Central

    Patterson, Rainey E.; Kalavalapalli, Srilaxmi; Williams, Caroline M.; Nautiyal, Manisha; Mathew, Justin T.; Martinez, Janie; Reinhard, Mary K.; McDougall, Danielle J.; Rocca, James R.; Yost, Richard A.; Cusi, Kenneth; Garrett, Timothy J.

    2016-01-01

    The hepatic tricarboxylic acid (TCA) cycle is central to integrating macronutrient metabolism and is closely coupled to cellular respiration, free radical generation, and inflammation. Oxidative flux through the TCA cycle is induced during hepatic insulin resistance, in mice and humans with simple steatosis, reflecting early compensatory remodeling of mitochondrial energetics. We hypothesized that progressive severity of hepatic insulin resistance and the onset of nonalcoholic steatohepatitis (NASH) would impair oxidative flux through the hepatic TCA cycle. Mice (C57/BL6) were fed a high-trans-fat high-fructose diet (TFD) for 8 wk to induce simple steatosis and NASH by 24 wk. In vivo fasting hepatic mitochondrial fluxes were determined by 13C-nuclear magnetic resonance (NMR)-based isotopomer analysis. Hepatic metabolic intermediates were quantified using mass spectrometry-based targeted metabolomics. Hepatic triglyceride accumulation and insulin resistance preceded alterations in mitochondrial metabolism, since TCA cycle fluxes remained normal during simple steatosis. However, mice with NASH had a twofold induction (P < 0.05) of mitochondrial fluxes (μmol/min) through the TCA cycle (2.6 ± 0.5 vs. 5.4 ± 0.6), anaplerosis (9.1 ± 1.2 vs. 16.9 ± 2.2), and pyruvate cycling (4.9 ± 1.0 vs. 11.1 ± 1.9) compared with their age-matched controls. Induction of the TCA cycle activity during NASH was concurrent with blunted ketogenesis and accumulation of hepatic diacylglycerols (DAGs), ceramides (Cer), and long-chain acylcarnitines, suggesting inefficient oxidation and disposal of excess free fatty acids (FFA). Sustained induction of mitochondrial TCA cycle failed to prevent accretion of “lipotoxic” metabolites in the liver and could hasten inflammation and the metabolic transition to NASH. PMID:26814015

  9. Streptomyces clavuligerus shows a strong association between TCA cycle intermediate accumulation and clavulanic acid biosynthesis.

    PubMed

    Ramirez-Malule, Howard; Junne, Stefan; Nicolás Cruz-Bournazou, Mariano; Neubauer, Peter; Ríos-Estepa, Rigoberto

    2018-05-01

    Clavulanic acid (CA) is produced by Streptomyces clavuligerus (S. clavuligerus) as a secondary metabolite. Knowledge about the carbon flux distribution along the various routes that supply CA precursors would certainly provide insights about metabolic performance. In order to evaluate metabolic patterns and the possible accumulation of tricarboxylic acid (TCA) cycle intermediates during CA biosynthesis, batch and subsequent continuous cultures with steadily declining feed rates were performed with glycerol as the main substrate. The data were used to in silico explore the metabolic capabilities and the accumulation of metabolic intermediates in S. clavuligerus. While clavulanic acid accumulated at glycerol excess, it steadily decreased at declining dilution rates; CA synthesis stopped when glycerol became the limiting substrate. A strong association of succinate, oxaloacetate, malate, and acetate accumulation with CA production in S. clavuligerus was observed, and flux balance analysis (FBA) was used to describe the carbon flux distribution in the network. This combined experimental and numerical approach also identified bottlenecks during the synthesis of CA in a batch and subsequent continuous cultivation and demonstrated the importance of this type of methodologies for a more advanced understanding of metabolism; this potentially derives valuable insights for future successful metabolic engineering studies in S. clavuligerus.

  10. Excessive Hepatic Mitochondrial TCA Cycle and Gluconeogenesis in Humans with Nonalcoholic Fatty Liver Disease

    PubMed Central

    Sunny, Nishanth E.; Parks, Elizabeth J.; Browning, Jeffrey D.; Burgess, Shawn C.

    2013-01-01

    Summary Approximately one-third of the U.S. population has nonalcoholic fatty liver disease (NAFLD), a condition closely associated with insulin resistance and increased risk of liver injury. Dysregulated mitochondrial metabolism is central in these disorders, but the manner and degree of dysregulation are disputed. This study tested whether humans with NAFLD have abnormal in vivo hepatic mitochondrial metabolism. Subjects with low (3.0%) and high (17%) intrahepatic triglyceride (IHTG) were studied using 2H and 13C tracers to evaluate systemic lipolysis, hepatic glucose production, and mitochondrial pathways (TCA cycle, anaplerosis, and ketogenesis). Individuals with NAFLD had 50% higher rates of lipolysis and 30% higher rates of gluconeogenesis. There was a positive correlation between IHTG content and both mitochondrial oxidative and anaplerotic fluxes. These data indicate that mitochondrial oxidative metabolism is ∼2-fold greater in those with NAFLD, providing a potential link between IHTG content, oxidative stress, and liver damage. PMID:22152305

  11. Integration of the tricarboxylic acid (TCA) cycle with cAMP signaling and Sfl2 pathways in the regulation of CO2 sensing and hyphal development in Candida albicans

    PubMed Central

    Tao, Li; Zhang, Yulong; Fan, Shuru; Nobile, Clarissa J.; Guan, Guobo; Huang, Guanghua

    2017-01-01

    Morphological transitions and metabolic regulation are critical for the human fungal pathogen Candida albicans to adapt to the changing host environment. In this study, we generated a library of central metabolic pathway mutants in the tricarboxylic acid (TCA) cycle, and investigated the functional consequences of these gene deletions on C. albicans biology. Inactivation of the TCA cycle impairs the ability of C. albicans to utilize non-fermentable carbon sources and dramatically attenuates cell growth rates under several culture conditions. By integrating the Ras1-cAMP signaling pathway and the heat shock factor-type transcription regulator Sfl2, we found that the TCA cycle plays fundamental roles in the regulation of CO2 sensing and hyphal development. The TCA cycle and cAMP signaling pathways coordinately regulate hyphal growth through the molecular linkers ATP and CO2. Inactivation of the TCA cycle leads to lowered intracellular ATP and cAMP levels and thus affects the activation of the Ras1-regulated cAMP signaling pathway. In turn, the Ras1-cAMP signaling pathway controls the TCA cycle through both Efg1- and Sfl2-mediated transcriptional regulation in response to elevated CO2 levels. The protein kinase A (PKA) catalytic subunit Tpk1, but not Tpk2, may play a major role in this regulation. Sfl2 specifically binds to several TCA cycle and hypha-associated genes under high CO2 conditions. Global transcriptional profiling experiments indicate that Sfl2 is indeed required for the gene expression changes occurring in response to these elevated CO2 levels. Our study reveals the regulatory role of the TCA cycle in CO2 sensing and hyphal development and establishes a novel link between the TCA cycle and Ras1-cAMP signaling pathways. PMID:28787458

  12. Origin of the Reductive Tricarboxylic Acid (rTCA) Cycle-Type CO2 Fixation: A Perspective

    PubMed Central

    Fujishima, Kosuke

    2017-01-01

    The reductive tricarboxylic acid (rTCA) cycle is among the most plausible candidates for the first autotrophic metabolism in the earliest life. Extant enzymes fixing CO2 in this cycle contain cofactors at the catalytic centers, but it is unlikely that the protein/cofactor system emerged at once in a prebiotic process. Here, we discuss the feasibility of non-enzymatic cofactor-assisted drive of the rTCA reactions in the primitive Earth environments, particularly focusing on the acetyl-CoA conversion to pyruvate. Based on the energetic and mechanistic aspects of this reaction, we propose that the deep-sea hydrothermal vent environments with active electricity generation in the presence of various sulfide catalysts are a promising setting for it to progress. Our view supports the theory of an autotrophic origin of life from primordial carbon assimilation within a sulfide-rich hydrothermal vent.

  13. Glucose-independent glutamine metabolism via TCA cycling for proliferation and survival in B-cells

    PubMed Central

    Le, Anne; Lane, Andrew N.; Hamaker, Max; Bose, Sminu; Gouw, Arvin; Barbi, Joseph; Tsukamoto, Takashi; Rojas, Camilio J.; Slusher, Barbara S.; Zhang, Haixia; Zimmerman, Lisa J.; Liebler, Daniel C.; Slebos, Robbert J.C.; Lorkiewicz, Pawel K.; Higashi, Richard M.; Fan, Teresa W. M.; Dang, Chi V.

    2012-01-01

    Summary Because MYC plays a causal role in many human cancers, including those with hypoxic and nutrient-poor tumor microenvironments, we have determined the metabolic responses of a MYC-inducible human Burkitt lymphoma model P493 cell line to aerobic and hypoxic conditions, and to glucose deprivation, using Stable Isotope Resolved Metabolomics. Using [U-13C]-glucose as the tracer, both glucose consumption and lactate production were increased by MYC expression and hypoxia. Using [U-13C,15N]-glutamine as the tracer, glutamine import and metabolism through the TCA cycle persisted under hypoxia, and glutamine contributed significantly to citrate carbons. Under glucose deprivation, glutamine-derived fumarate, malate, and citrate were significantly increased. Their 13C labeling patterns demonstrate an alternative energy-generating glutaminolysis pathway involving a glucose-independent TCA cycle. The essential role of glutamine metabolism in cell survival and proliferation under hypoxia and glucose deficiency, makes them susceptible to the glutaminase inhibitor BPTES, and hence could be targeted for cancer therapy. PMID:22225880

  14. Integrated, Step-Wise, Mass-Isotopomeric Flux Analysis of the TCA Cycle.

    PubMed

    Alves, Tiago C; Pongratz, Rebecca L; Zhao, Xiaojian; Yarborough, Orlando; Sereda, Sam; Shirihai, Orian; Cline, Gary W; Mason, Graeme; Kibbey, Richard G

    2015-11-03

    Mass isotopomer multi-ordinate spectral analysis (MIMOSA) is a step-wise flux analysis platform to measure discrete glycolytic and mitochondrial metabolic rates. Importantly, direct citrate synthesis rates were obtained by deconvolving the mass spectra generated from [U-(13)C6]-D-glucose labeling for position-specific enrichments of mitochondrial acetyl-CoA, oxaloacetate, and citrate. Comprehensive steady-state and dynamic analyses of key metabolic rates (pyruvate dehydrogenase, β-oxidation, pyruvate carboxylase, isocitrate dehydrogenase, and PEP/pyruvate cycling) were calculated from the position-specific transfer of (13)C from sequential precursors to their products. Important limitations of previous techniques were identified. In INS-1 cells, citrate synthase rates correlated with both insulin secretion and oxygen consumption. Pyruvate carboxylase rates were substantially lower than previously reported but showed the highest fold change in response to glucose stimulation. In conclusion, MIMOSA measures key metabolic rates from the precursor/product position-specific transfer of (13)C-label between metabolites and has broad applicability to any glucose-oxidizing cell. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. [Metabolic flux analysis of L-serine synthesis by Corynebacterium glutamicum SYPS-062].

    PubMed

    Zhang, Xiaomei; Dou, Wenfang; Xu, Hongyu; Xu, Zhenghong

    2010-10-01

    Corynebacterium glutamicum SYPS-062 was an L-serine producing strain stored at our lab and could produce L-serine directly from sugar. We studied the effects of cofactors in one carbon unit metabolism-folate and VB12 on the cell growth, sucrose consumption and L-serine production by SYPS-062. In the same time, the metabolic flux distribution was determined in different conditions. The supplementation of folate or VB12 enhanced the cell growth, energy synthesis, and finally increased the flux of pentose phosphate pathway (HMP), whereas the carbon flux to L-serine was decreased. The addition of VB12 not only increased the ratio of L-serine synthesis pathway on G3P joint, but also caused the insufficiency of tricarboxylic acid cycle (TCA) flux, which needed more anaplerotic reaction flux to replenish TCA cycle, that was an important limiting factor for the further increasing of the L-serine productivity.

  16. Systematic engineering of TCA cycle for optimal production of a four-carbon platform chemical 4-hydroxybutyric acid in Escherichia coli.

    PubMed

    Choi, Sol; Kim, Hyun Uk; Kim, Tae Yong; Lee, Sang Yup

    2016-11-01

    To address climate change and environmental problems, it is becoming increasingly important to establish biorefineries for the production of chemicals from renewable non-food biomass. Here we report the development of Escherichia coli strains capable of overproducing a four-carbon platform chemical 4-hybroxybutyric acid (4-HB). Because 4-HB production is significantly affected by aeration level, genome-scale metabolic model-based engineering strategies were designed under aerobic and microaerobic conditions with emphasis on oxidative/reductive TCA branches and glyoxylate shunt. Several different metabolic engineering strategies were employed to develop strains suitable for fermentation both under aerobic and microaerobic conditions. It was found that microaerobic condition was more efficient than aerobic condition in achieving higher titer and productivity of 4-HB. The final engineered strain produced 103.4g/L of 4-HB by microaerobic fed-batch fermentation using glycerol. The aeration-dependent optimization strategy of TCA cycle will be useful for developing microbial strains producing other reduced derivative chemicals of TCA cycle intermediates. Copyright © 2016 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

  17. Inhibition of Pyruvate Dehydrogenase Kinase 2 Protects Against Hepatic Steatosis Through Modulation of Tricarboxylic Acid Cycle Anaplerosis and Ketogenesis.

    PubMed

    Go, Younghoon; Jeong, Ji Yun; Jeoung, Nam Ho; Jeon, Jae-Han; Park, Bo-Yoon; Kang, Hyeon-Ji; Ha, Chae-Myeong; Choi, Young-Keun; Lee, Sun Joo; Ham, Hye Jin; Kim, Byung-Gyu; Park, Keun-Gyu; Park, So Young; Lee, Chul-Ho; Choi, Cheol Soo; Park, Tae-Sik; Lee, W N Paul; Harris, Robert A; Lee, In-Kyu

    2016-10-01

    Hepatic steatosis is associated with increased insulin resistance and tricarboxylic acid (TCA) cycle flux, but decreased ketogenesis and pyruvate dehydrogenase complex (PDC) flux. This study examined whether hepatic PDC activation by inhibition of pyruvate dehydrogenase kinase 2 (PDK2) ameliorates these metabolic abnormalities. Wild-type mice fed a high-fat diet exhibited hepatic steatosis, insulin resistance, and increased levels of pyruvate, TCA cycle intermediates, and malonyl-CoA but reduced ketogenesis and PDC activity due to PDK2 induction. Hepatic PDC activation by PDK2 inhibition attenuated hepatic steatosis, improved hepatic insulin sensitivity, reduced hepatic glucose production, increased capacity for β-oxidation and ketogenesis, and decreased the capacity for lipogenesis. These results were attributed to altered enzymatic capacities and a reduction in TCA anaplerosis that limited the availability of oxaloacetate for the TCA cycle, which promoted ketogenesis. The current study reports that increasing hepatic PDC activity by inhibition of PDK2 ameliorates hepatic steatosis and insulin sensitivity by regulating TCA cycle anaplerosis and ketogenesis. The findings suggest PDK2 is a potential therapeutic target for nonalcoholic fatty liver disease. © 2016 by the American Diabetes Association.

  18. TCA cycle rewiring fosters metabolic adaptation to oxygen restriction in skeletal muscle from rodents and humans.

    PubMed

    Capitanio, Daniele; Fania, Chiara; Torretta, Enrica; Viganò, Agnese; Moriggi, Manuela; Bravatà, Valentina; Caretti, Anna; Levett, Denny Z H; Grocott, Michael P W; Samaja, Michele; Cerretelli, Paolo; Gelfi, Cecilia

    2017-08-29

    In mammals, hypoxic stress management is under the control of the Hypoxia Inducible Factors, whose activity depends on the stabilization of their labile α subunit. In particular, the skeletal muscle appears to be able to react to changes in substrates and O 2 delivery by tuning its metabolism. The present study provides a comprehensive overview of skeletal muscle metabolic adaptation to hypoxia in mice and in human subjects exposed for 7/9 and 19 days to high altitude levels. The investigation was carried out combining proteomics, qRT-PCR mRNA transcripts analysis, and enzyme activities assessment in rodents, and protein detection by antigen antibody reactions in humans and rodents. Results indicate that the skeletal muscle react to a decreased O 2 delivery by rewiring the TCA cycle. The first TCA rewiring occurs in mice in 2-day hypoxia and is mediated by cytosolic malate whereas in 10-day hypoxia the rewiring is mediated by Idh1 and Fasn, supported by glutamine and HIF-2α increments. The combination of these specific anaplerotic steps can support energy demand despite HIFs degradation. These results were confirmed in human subjects, demonstrating that the TCA double rewiring represents an essential factor for the maintenance of muscle homeostasis during adaptation to hypoxia.

  19. Anaerobic Respiration Using a Complete Oxidative TCA Cycle Drives Multicellular Swarming in Proteus mirabilis

    PubMed Central

    Alteri, Christopher J.; Himpsl, Stephanie D.; Engstrom, Michael D.; Mobley, Harry L. T.

    2012-01-01

    ABSTRACT Proteus mirabilis rapidly migrates across surfaces using a periodic developmental process of differentiation alternating between short swimmer cells and elongated hyperflagellated swarmer cells. To undergo this vigorous flagellum-mediated motility, bacteria must generate a substantial proton gradient across their cytoplasmic membranes by using available energy pathways. We sought to identify the link between energy pathways and swarming differentiation by examining the behavior of defined central metabolism mutants. Mutations in the tricarboxylic acid (TCA) cycle (fumC and sdhB mutants) caused altered patterns of swarming periodicity, suggesting an aerobic pathway. Surprisingly, the wild-type strain swarmed on agar containing sodium azide, which poisons aerobic respiration; the fumC TCA cycle mutant, however, was unable to swarm on azide. To identify other contributing energy pathways, we screened transposon mutants for loss of swarming on sodium azide and found insertions in the following genes that involved fumarate metabolism or respiration: hybB, encoding hydrogenase; fumC, encoding fumarase; argH, encoding argininosuccinate lyase (generates fumarate); and a quinone hydroxylase gene. These findings validated the screen and suggested involvement of anaerobic electron transport chain components. Abnormal swarming periodicity of fumC and sdhB mutants was associated with the excretion of reduced acidic fermentation end products. Bacteria lacking SdhB were rescued to wild-type pH and periodicity by providing fumarate, independent of carbon source but dependent on oxygen, while fumC mutants were rescued by glycerol, independent of fumarate only under anaerobic conditions. These findings link multicellular swarming patterns with fumarate metabolism and membrane electron transport using a previously unappreciated configuration of both aerobic and anaerobic respiratory chain components. PMID:23111869

  20. The TCA cycle is not required for selection or survival of multidrug-resistant Salmonella

    PubMed Central

    Ricci, Vito; Loman, Nick; Pallen, Mark; Ivens, Alasdair; Fookes, Maria; Langridge, Gemma C.; Wain, John; Piddock, Laura J. V.

    2012-01-01

    Objectives The initial aim of this study was to use a systems biology approach to analyse a ciprofloxacin-selected multidrug-resistant (MDR) Salmonella enterica serotype Typhimurium, L664. Methods The whole genome sequence and transcriptome of L664 were analysed. Site-directed mutagenesis to recreate each mutation was carried out, followed by phenotypic characterization and mutation frequency analysis. As a mutation in the TCA cycle was detected we tested the controversial hypothesis regarding the bacterial response to bactericidal antibiotics, put forward by Kohanski et al. (Cell 2007; 130: 797–810 and Mol Cell 2010; 37: 311–20), that exposure of bacteria to agents such as ciprofloxacin produces reactive oxygen species (ROS), which transiently increase the mutation rate giving rise to MDR bacteria. Results L664 contained a mutation in ramR that conferred MDR. A mutation in tctA affected the TCA cycle and conferred the inability to grow on minimal agar. The virulence of L664 was not attenuated. Ciprofloxacin exposure produced ROS in L664 and SL1344 (tctA::aph), but it was reduced and occurred later. There were no significant differences in the rates of killing or mutations per generation to antibiotic resistance between the strains. Conclusions Whilst we confirm production of ROS in response to ciprofloxacin, we have no data to support the hypothesis that this leads to selection of MDR strains. Our results indicate that the mutations in tctA and glgA were random as they did not pre-exist in the parental strain, and that the mutation in tctA did not provide a survival advantage or disadvantage in the presence of antibiotic. PMID:22186876

  1. Disruption of TCA Cycle and Glutamate Metabolism Identified by Metabolomics in an In Vitro Model of Amyotrophic Lateral Sclerosis.

    PubMed

    Veyrat-Durebex, Charlotte; Corcia, Philippe; Piver, Eric; Devos, David; Dangoumau, Audrey; Gouel, Flore; Vourc'h, Patrick; Emond, Patrick; Laumonnier, Frédéric; Nadal-Desbarats, Lydie; Gordon, Paul H; Andres, Christian R; Blasco, Hélène

    2016-12-01

    This study aims to develop a cellular metabolomics model that reproduces the pathophysiological conditions found in amyotrophic lateral sclerosis in order to improve knowledge of disease physiology. We used a co-culture model combining the motor neuron-like cell line NSC-34 and the astrocyte clone C8-D1A, with each over-expressing wild-type or G93C mutant human SOD1, to examine amyotrophic lateral sclerosis (ALS) physiology. We focused on the effects of mutant human SOD1 as well as oxidative stress induced by menadione on intracellular metabolism using a metabolomics approach through gas chromatography coupled with mass spectrometry (GC-MS) analysis. Preliminary non-supervised analysis by Principal Component Analysis (PCA) revealed that cell type, genetic environment, and time of culture influenced the metabolomics profiles. Supervised analysis using orthogonal partial least squares discriminant analysis (OPLS-DA) on data from intracellular metabolomics profiles of SOD1 G93C co-cultures produced metabolites involved in glutamate metabolism and the tricarboxylic acid cycle (TCA) cycle. This study revealed the feasibility of using a metabolomics approach in a cellular model of ALS. We identified potential disruption of the TCA cycle and glutamate metabolism under oxidative stress, which is consistent with prior research in the disease. Analysis of metabolic alterations in an in vitro model is a novel approach to investigation of disease physiology.

  2. Pyruvate cycle increases aminoglycoside efficacy and provides respiratory energy in bacteria.

    PubMed

    Su, Yu-Bin; Peng, Bo; Li, Hui; Cheng, Zhi-Xue; Zhang, Tian-Tuo; Zhu, Jia-Xin; Li, Dan; Li, Min-Yi; Ye, Jin-Zhou; Du, Chao-Chao; Zhang, Song; Zhao, Xian-Liang; Yang, Man-Jun; Peng, Xuan-Xian

    2018-02-13

    The emergence and ongoing spread of multidrug-resistant bacteria puts humans and other species at risk for potentially lethal infections. Thus, novel antibiotics or alternative approaches are needed to target drug-resistant bacteria, and metabolic modulation has been documented to improve antibiotic efficacy, but the relevant metabolic mechanisms require more studies. Here, we show that glutamate potentiates aminoglycoside antibiotics, resulting in improved elimination of antibiotic-resistant pathogens. When exploring the metabolic flux of glutamate, it was found that the enzymes that link the phosphoenolpyruvate (PEP)-pyruvate-AcCoA pathway to the TCA cycle were key players in this increased efficacy. Together, the PEP-pyruvate-AcCoA pathway and TCA cycle can be considered the pyruvate cycle (P cycle). Our results show that inhibition or gene depletion of the enzymes in the P cycle shut down the TCA cycle even in the presence of excess carbon sources, and that the P cycle operates routinely as a general mechanism for energy production and regulation in Escherichia coli and Edwardsiella tarda These findings address metabolic mechanisms of metabolite-induced potentiation and fundamental questions about bacterial biochemistry and energy metabolism.

  3. Genetic investigation of tricarboxylic acid metabolism during the Plasmodium falciparum life cycle.

    PubMed

    Ke, Hangjun; Lewis, Ian A; Morrisey, Joanne M; McLean, Kyle J; Ganesan, Suresh M; Painter, Heather J; Mather, Michael W; Jacobs-Lorena, Marcelo; Llinás, Manuel; Vaidya, Akhil B

    2015-04-07

    New antimalarial drugs are urgently needed to control drug-resistant forms of the malaria parasite Plasmodium falciparum. Mitochondrial electron transport is the target of both existing and new antimalarials. Herein, we describe 11 genetic knockout (KO) lines that delete six of the eight mitochondrial tricarboxylic acid (TCA) cycle enzymes. Although all TCA KOs grew normally in asexual blood stages, these metabolic deficiencies halted life-cycle progression in later stages. Specifically, aconitase KO parasites arrested as late gametocytes, whereas α-ketoglutarate-dehydrogenase-deficient parasites failed to develop oocysts in the mosquitoes. Mass spectrometry analysis of (13)C-isotope-labeled TCA mutant parasites showed that P. falciparum has significant flexibility in TCA metabolism. This flexibility manifested itself through changes in pathway fluxes and through altered exchange of substrates between cytosolic and mitochondrial pools. Our findings suggest that mitochondrial metabolic plasticity is essential for parasite development. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Glutamatergic and GABAergic neurotransmitter cycling and energy metabolism in rat cerebral cortex during postnatal development.

    PubMed

    Chowdhury, Golam M I; Patel, Anant B; Mason, Graeme F; Rothman, Douglas L; Behar, Kevin L

    2007-12-01

    The contribution of glutamatergic and gamma-aminobutyric acid (GABA)ergic neurons to oxidative energy metabolism and neurotransmission in the developing brain is not known. Glutamatergic and GABAergic fluxes were assessed in neocortex of postnatal day 10 (P10) and 30 (P30) urethane-anesthetized rats infused intravenously with [1,6-(13)C(2)]glucose for different time intervals (time course) or with [2-(13)C]acetate for 2 to 3 h (steady state). Amino acid levels and (13)C enrichments were determined in tissue extracts ex vivo using (1)H-[(13)C]-NMR spectroscopy. Metabolic fluxes were estimated from the best fits of a three-compartment metabolic model (glutamatergic neurons, GABAergic neurons, and astroglia) to the (13)C-enrichment time courses of amino acids from [1,6-(13)C(2)]glucose, constrained by the ratios of neurotransmitter cycling (V(cyc))-to-tricarboxylic acid (TCA) cycle flux (V(TCAn)) calculated from the steady-state [2-(13)C]acetate enrichment data. From P10 to P30 increases in total neuronal (glutamate plus GABA) TCA cycle flux (3 x ; 0.24+/-0.05 versus 0.71+/-0.07 micromol per g per min, P<0.0001) and total neurotransmitter cycling flux (3.1 to 5 x ; 0.07 to 0.11 (+/-0.03) versus 0.34+/-0.03 micromol per g per min, P<0.0001) were approximately proportional. Incremental changes in total cycling (DeltaV(cyc(tot))) and neuronal TCA cycle flux (DeltaV(TCAn(tot))) between P10 and P30 were 0.23 to 0.27 and 0.47 micromol per g per min, respectively, similar to the approximately 1:2 relationship previously reported for adult cortex. For the individual neurons, increases in V(TCAn) and V(cyc) were similar in magnitude (glutamatergic neurons, 2.7 x versus 2.8 to 4.6 x ; GABAergic neurons, approximately 5 x versus approximately 7 x), although GABAergic flux changes were larger. The findings show that glutamate and GABA neurons undergo large and approximately proportional increases in neurotransmitter cycling and oxidative energy metabolism during this major

  5. (13)C-metabolic flux analysis in S-adenosyl-L-methionine production by Saccharomyces cerevisiae.

    PubMed

    Hayakawa, Kenshi; Kajihata, Shuichi; Matsuda, Fumio; Shimizu, Hiroshi

    2015-11-01

    S-Adenosyl-L-methionine (SAM) is a major biological methyl group donor, and is used as a nutritional supplement and prescription drug. Yeast is used for the industrial production of SAM owing to its high intracellular SAM concentrations. To determine the regulation mechanisms responsible for such high SAM production, (13)C-metabolic flux analysis ((13)C-MFA) was conducted to compare the flux distributions in the central metabolism between Kyokai no. 6 (high SAM-producing) and S288C (control) strains. (13)C-MFA showed that the levels of tricarboxylic acid (TCA) cycle flux in SAM-overproducing strain were considerably increased compared to those in the S228C strain. Analysis of ATP balance also showed that a larger amount of excess ATP was produced in the Kyokai 6 strain because of increased oxidative phosphorylation. These results suggest that high SAM production in Kyokai 6 strains could be attributed to enhanced ATP regeneration with high TCA cycle fluxes and respiration activity. Thus, maintaining high respiration efficiency during cultivation is important for improving SAM production. Copyright © 2015 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  6. Rates of insulin secretion in INS-1 cells are enhanced by coupling to anaplerosis and Kreb's cycle flux independent of ATP synthesis.

    PubMed

    Cline, Gary W; Pongratz, Rebecca L; Zhao, Xiaojian; Papas, Klearchos K

    2011-11-11

    Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as a surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with (31)P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by (13)C NMR isotopomer analysis of the fate of [U-(13)C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria were found to be similar in DMEM to those in KRB. And, the correlation of total PC flux with insulin secretion rates in DMEM was found to be congruous with the correlation in KRB. Together, these results suggest that signaling mechanisms associated with both TCA cycle flux and with anaplerotic flux, but not ATP production, may be responsible for the enhanced rates of insulin secretion in more complex, and physiologically-relevant media. Copyright © 2011 Elsevier Inc. All

  7. TCA High Lift Preliminary Assessment

    NASA Technical Reports Server (NTRS)

    Wyatt, G. H.; Polito, R. C.; Yeh, D. T.; Elzey, M. E.; Tran, J. T.; Meredith, Paul T.

    1999-01-01

    This paper presents a TCA (Technology Concept Airplane) High lift Preliminary Assessment. The topics discussed are: 1) Model Description; 2) Data Repeatability; 3) Effect of Inboard L.E. (Leading Edge) Flap Span; 4) Comparison of 14'x22' TCA-1 With NTF (National Transonic Facility) Modified Ref. H; 5) Comparison of 14'x22' and NTF Ref. H Results; 6) Effect of Outboard Sealed Slat on TCA; 7) TCA Full Scale Build-ups; 8) Full Scale L/D Comparisons; 9) TCA Full Scale; and 10) Touchdown Lift Curves. This paper is in viewgraph form.

  8. Glutamate oxaloacetate transaminase enables anaplerotic refilling of TCA cycle intermediates in stroke-affected brain

    PubMed Central

    Rink, Cameron; Gnyawali, Surya; Stewart, Richard; Teplitsky, Seth; Harris, Hallie; Roy, Sashwati; Sen, Chandan K.; Khanna, Savita

    2017-01-01

    Ischemic stroke results in excessive release of glutamate, which contributes to neuronal cell death. Here, we test the hypothesis that otherwise neurotoxic glutamate can be productively metabolized by glutamate oxaloacetate transaminase (GOT) to maintain cellular energetics and protect the brain from ischemic stroke injury. The GOT-dependent metabolism of glutamate was studied in primary neural cells and in stroke-affected C57-BL6 mice using magnetic resonance spectroscopy and GC-MS. Extracellular Glu sustained cell viability under hypoglycemic conditions and increased GOT-mediated metabolism in vitro. Correction of stroke-induced hypoxia using supplemental oxygen in vivo lowered Glu levels as measured by 1H magnetic resonance spectroscopy. GOT knockdown abrogated this effect and caused ATP loss in the stroke-affected brain. GOT overexpression increased anaplerotic refilling of tricarboxylic acid cycle intermediates in mouse brain during ischemic stroke. Furthermore, GOT overexpression not only reduced ischemic stroke lesion volume but also attenuated neurodegeneration and improved poststroke sensorimotor function. Taken together, our results show that GOT enables metabolism of otherwise neurotoxic extracellular Glu through a truncated tricarboxylic acid cycle under hypoglycemic conditions.—Rink, C., Gnyawali, S., Stewart, R., Teplitsky, S., Harris, H., Roy, S., Sen, C. K., Khanna, S. Glutamate oxaloacetate transaminase enables anaplerotic refilling of TCA cycle intermediates in stroke-affected brain. PMID:28096234

  9. TCA precipitation.

    PubMed

    Koontz, Laura

    2014-01-01

    Trichloroacetic acid (TCA) precipitation of proteins is commonly used to concentrate protein samples or remove contaminants, including salts and detergents, prior to downstream applications such as SDS-PAGE or 2D-gels. TCA precipitation denatures the protein, so it should not be used if the protein must remain in its folded state (e.g., if you want to measure a biochemical activity of the protein). © 2014 Elsevier Inc. All rights reserved.

  10. A Process-Based Model of TCA Cycle Functioning to Analyze Citrate Accumulation in Pre- and Post-Harvest Fruits.

    PubMed

    Etienne, Audrey; Génard, Michel; Bugaud, Christophe

    2015-01-01

    Citrate is one of the most important organic acids in many fruits and its concentration plays a critical role in organoleptic properties. The regulation of citrate accumulation throughout fruit development, and the origins of the phenotypic variability of the citrate concentration within fruit species remain to be clarified. In the present study, we developed a process-based model of citrate accumulation based on a simplified representation of the TCA cycle to predict citrate concentration in fruit pulp during the pre- and post-harvest stages. Banana fruit was taken as a reference because it has the particularity of having post-harvest ripening, during which citrate concentration undergoes substantial changes. The model was calibrated and validated on the two stages, using data sets from three contrasting cultivars in terms of citrate accumulation, and incorporated different fruit load, potassium supply, and harvest dates. The model predicted the pre and post-harvest dynamics of citrate concentration with fairly good accuracy for the three cultivars. The model suggested major differences in TCA cycle functioning among cultivars during post-harvest ripening of banana, and pointed to a potential role for NAD-malic enzyme and mitochondrial malate carriers in the genotypic variability of citrate concentration. The sensitivity of citrate accumulation to growth parameters and temperature differed among cultivars during post-harvest ripening. Finally, the model can be used as a conceptual basis to study citrate accumulation in fleshy fruits and may be a powerful tool to improve our understanding of fruit acidity.

  11. Revealing Differences in Metabolic Flux Distributions between a Mutant Strain and Its Parent Strain Gluconacetobacter xylinus CGMCC 2955

    PubMed Central

    Liu, Miao; Yang, Xiao-Ning; Zhu, Hui-Xia; Jia, Yuan-Yuan; Jia, Shi-Ru; Piergiovanni, Luciano

    2014-01-01

    A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain. PMID:24901455

  12. Metabolic flux profiling of MDCK cells during growth and canine adenovirus vector production.

    PubMed

    Carinhas, Nuno; Pais, Daniel A M; Koshkin, Alexey; Fernandes, Paulo; Coroadinha, Ana S; Carrondo, Manuel J T; Alves, Paula M; Teixeira, Ana P

    2016-03-23

    Canine adenovirus vector type 2 (CAV2) represents an alternative to human adenovirus vectors for certain gene therapy applications, particularly neurodegenerative diseases. However, more efficient production processes, assisted by a greater understanding of the effect of infection on producer cells, are required. Combining [1,2-(13)C]glucose and [U-(13)C]glutamine, we apply for the first time (13)C-Metabolic flux analysis ((13)C-MFA) to study E1-transformed Madin-Darby Canine Kidney (MDCK) cells metabolism during growth and CAV2 production. MDCK cells displayed a marked glycolytic and ammoniagenic metabolism, and (13)C data revealed a large fraction of glutamine-derived labelling in TCA cycle intermediates, emphasizing the role of glutamine anaplerosis. (13)C-MFA demonstrated the importance of pyruvate cycling in balancing glycolytic and TCA cycle activities, as well as occurrence of reductive alphaketoglutarate (AKG) carboxylation. By turn, CAV2 infection significantly upregulated fluxes through most central metabolism, including glycolysis, pentose-phosphate pathway, glutamine anaplerosis and, more prominently, reductive AKG carboxylation and cytosolic acetyl-coenzyme A formation, suggestive of increased lipogenesis. Based on these results, we suggest culture supplementation strategies to stimulate nucleic acid and lipid biosynthesis for improved canine adenoviral vector production.

  13. Index markers of chronic fatigue syndrome with dysfunction of TCA and urea cycles

    PubMed Central

    Yamano, Emi; Sugimoto, Masahiro; Hirayama, Akiyoshi; Kume, Satoshi; Yamato, Masanori; Jin, Guanghua; Tajima, Seiki; Goda, Nobuhito; Iwai, Kazuhiro; Fukuda, Sanae; Yamaguti, Kouzi; Kuratsune, Hirohiko; Soga, Tomoyoshi; Watanabe, Yasuyoshi; Kataoka, Yosky

    2016-01-01

    Chronic fatigue syndrome (CFS) is a persistent and unexplained pathological state characterized by exertional and severely debilitating fatigue, with/without infectious or neuropsychiatric symptoms, lasting at least 6 consecutive months. Its pathogenesis remains incompletely understood. Here, we performed comprehensive metabolomic analyses of 133 plasma samples obtained from CFS patients and healthy controls to establish an objective diagnosis of CFS. CFS patients exhibited significant differences in intermediate metabolite concentrations in the tricarboxylic acid (TCA) and urea cycles. The combination of ornithine/citrulline and pyruvate/isocitrate ratios discriminated CFS patients from healthy controls, yielding area under the receiver operating characteristic curve values of 0.801 (95% confidential interval [CI]: 0.711–0.890, P < 0.0001) and 0.750 (95% CI: 0.584–0.916, P = 0.0069) for training (n = 93) and validation (n = 40) datasets, respectively. These findings provide compelling evidence that a clinical diagnostic tool could be developed for CFS based on the ratios of metabolites in plasma. PMID:27725700

  14. Comparison of Optimal Thermodynamic Models of the Tricarboxylic Acid Cycle from Heterotrophs, Cyanobacteria, and Green Sulfur Bacteria.

    PubMed

    Thomas, Dennis G; Jaramillo-Riveri, Sebastian; Baxter, Douglas J; Cannon, William R

    2014-12-26

    We have applied a new stochastic simulation approach to predict the metabolite levels, material flux, and thermodynamic profiles of the oxidative TCA cycles found in E. coli and Synechococcus sp. PCC 7002, and in the reductive TCA cycle typical of chemolithoautotrophs and phototrophic green sulfur bacteria such as Chlorobaculum tepidum. The simulation approach is based on modeling states using statistical thermodynamics and employs an assumption similar to that used in transition state theory. The ability to evaluate the thermodynamics of metabolic pathways allows one to understand the relationship between coupling of energy and material gradients in the environment and the self-organization of stable biological systems, and it is shown that each cycle operates in the direction expected due to its environmental niche. The simulations predict changes in metabolite levels and flux in response to changes in cofactor concentrations that would be hard to predict without an elaborate model based on the law of mass action. In fact, we show that a thermodynamically unfavorable reaction can still have flux in the forward direction when it is part of a reaction network. The ability to predict metabolite levels, energy flow, and material flux should be significant for understanding the dynamics of natural systems and for understanding principles for engineering organisms for production of specialty chemicals.

  15. Magnetic Flux Emergence Along the Solar Cycle

    NASA Astrophysics Data System (ADS)

    Schmieder, B.; Archontis, V.; Pariat, E.

    2014-12-01

    Flux emergence plays an important role along the solar cycle. Magnetic flux emergence builds sunspot groups and solar activity. The sunspot groups contribute to the large scale behaviour of the magnetic field over the 11 year cycle and the reversal of the North and South magnetic polarity every 22 years. The leading polarity of sunspot groups is opposite in the North and South hemispheres and reverses for each new solar cycle. However the hemispheric rule shows the conservation of sign of the magnetic helicity with positive and negative magnetic helicity in the South and North hemispheres, respectively. MHD models of emerging flux have been developed over the past twenty years but have not yet succeeded to reproduce solar observations. The emergence of flux occurs through plasma layers of very high gradients of pressure and changing of modes from a large β to a low β plasma (<1). With the new armada of high spatial and temporal resolution instruments on the ground and in space, emergence of magnetic flux is observed in tremendous detail and followed during their transit through the upper atmosphere. Signatures of flux emergence in the corona depend on the pre-existing magnetic configuration and on the strength of the emerging flux. We review in this paper new and established models as well as the recent observations.

  16. Glutamine oxidation maintains the TCA cycle and cell survival during impaired mitochondrial pyruvate transport.

    PubMed

    Yang, Chendong; Ko, Bookyung; Hensley, Christopher T; Jiang, Lei; Wasti, Ajla T; Kim, Jiyeon; Sudderth, Jessica; Calvaruso, Maria Antonietta; Lumata, Lloyd; Mitsche, Matthew; Rutter, Jared; Merritt, Matthew E; DeBerardinis, Ralph J

    2014-11-06

    Alternative modes of metabolism enable cells to resist metabolic stress. Inhibiting these compensatory pathways may produce synthetic lethality. We previously demonstrated that glucose deprivation stimulated a pathway in which acetyl-CoA was formed from glutamine downstream of glutamate dehydrogenase (GDH). Here we show that import of pyruvate into the mitochondria suppresses GDH and glutamine-dependent acetyl-CoA formation. Inhibiting the mitochondrial pyruvate carrier (MPC) activates GDH and reroutes glutamine metabolism to generate both oxaloacetate and acetyl-CoA, enabling persistent tricarboxylic acid (TCA) cycle function. Pharmacological blockade of GDH elicited largely cytostatic effects in culture, but these effects became cytotoxic when combined with MPC inhibition. Concomitant administration of MPC and GDH inhibitors significantly impaired tumor growth compared to either inhibitor used as a single agent. Together, the data define a mechanism to induce glutaminolysis and uncover a survival pathway engaged during compromised supply of pyruvate to the mitochondria. Copyright © 2014 Elsevier Inc. All rights reserved.

  17. Glutamine oxidation maintains the TCA cycle and cell survival during impaired mitochondrial pyruvate transport

    PubMed Central

    Yang, Chendong; Ko, Bookyung; Hensley, Christopher T.; Jiang, Lei; Wasti, Ajla T.; Kim, Jiyeon; Sudderth, Jessica; Calvaruso, Maria Antonietta; Lumata, Lloyd; Mitsche, Matthew; Rutter, Jared; Merritt, Matthew E.; DeBerardinis, Ralph J.

    2014-01-01

    Summary Alternative modes of metabolism enable cells to resist metabolic stress. Inhibiting these compensatory pathways may produce synthetic lethality. We previously demonstrated that glucose deprivation stimulated a pathway in which acetyl-CoA was formed from glutamine downstream of glutamate dehydrogenase (GDH). Here we show that import of pyruvate into the mitochondria suppresses GDH and glutamine-dependent acetyl-CoA formation. Inhibiting the mitochondrial pyruvate carrier (MPC) activates GDH and re-routes glutamine metabolism to generate both oxaloacetate and acetyl-CoA, enabling persistent tricarboxylic acid (TCA) cycle function. Pharmacological blockade of GDH elicited largely cytostatic effects in culture, but these effects became cytotoxic when combined with MPC inhibition. Concomitant administration of MPC and GDH inhibitors significantly impaired tumor growth compared to either inhibitor used as a single agent. Together, the data define a mechanism to induce glutaminolysis and uncover a survival pathway engaged during compromised supply of pyruvate to the mitochondria. PMID:25458842

  18. Modern Estimates of Global Water Cycle Fluxes

    NASA Astrophysics Data System (ADS)

    Rodell, M.; Beaudoing, H. K.; L'Ecuyer, T. S.; Olson, W. S.

    2014-12-01

    The goal of the first phase of the NASA Energy and Water Cycle Study (NEWS) Water and Energy Cycle Climatology project was to develop "state of the global water cycle" and "state of the global energy cycle" assessments based on data from modern ground and space based observing systems and data integrating models. Here we describe results of the water cycle assessment, including mean annual and monthly fluxes over continents and ocean basins during the first decade of the millennium. To the extent possible, the water flux estimates are based on (1) satellite measurements and (2) data-integrating models. A careful accounting of uncertainty in each flux was applied within a routine that enforced multiple water and energy budget constraints simultaneously in a variational framework, in order to produce objectively-determined, optimized estimates. Simultaneous closure of the water and energy budgets caused the ocean evaporation and precipitation terms to increase by about 10% and 5% relative to the original estimates, mainly because the energy budget required turbulent heat fluxes to be substantially larger in order to balance net radiation. In the majority of cases, the observed annual, surface and atmospheric water budgets over the continents and oceans close with much less than 10% residual. Observed residuals and optimized uncertainty estimates are considerably larger for monthly surface and atmospheric water budget closure, often nearing or exceeding 20% in North America, Eurasia, Australia and neighboring islands, and the Arctic and South Atlantic Oceans. The residuals in South America and Africa tend to be smaller, possibly because cold land processes are a non-issue. Fluxes are poorly observed over the Arctic Ocean, certain seas, Antarctica, and the Australasian and Indonesian Islands, leading to reliance on atmospheric analysis estimates. Other details of the study and future directions will be discussed.

  19. Neuronal glucose metabolism is impaired while astrocytic TCA cycling is unaffected at symptomatic stages in the hSOD1G93A mouse model of amyotrophic lateral sclerosis.

    PubMed

    Tefera, Tesfaye W; Borges, Karin

    2018-01-01

    Although alterations in energy metabolism are known in ALS, the specific mechanisms leading to energy deficit are not understood. We measured metabolite levels derived from injected [1- 13 C]glucose and [1,2- 13 C]acetate (i.p.) in cerebral cortex and spinal cord extracts of wild type and hSOD1 G93A mice at onset and mid disease stages using high-pressure liquid chromatography, 1 H and 13 C nuclear magnetic resonance spectroscopy. Levels of spinal and cortical CNS total lactate, [3- 13 C]lactate, total alanine and [3- 13 C]alanine, but not cortical glucose and [1- 13 C]glucose, were reduced mostly at mid stage indicating impaired glycolysis. The [1- 13 C]glucose-derived [4- 13 C]glutamate, [4- 13 C]glutamine and [2- 13 C]GABA amounts were diminished at mid stage in cortex and both time points in spinal cord, suggesting decreased [3- 13 C]pyruvate entry into the TCA cycle. Lack of changes in [1,2- 13 C]acetate-derived [4,5- 13 C]glutamate, [4,5- 13 C]glutamine and [1,2- 13 C]GABA levels indicate unchanged astrocytic 13 C-acetate metabolism. Reduced levels of leucine, isoleucine and valine in CNS suggest compensatory breakdown to refill TCA cycle intermediate levels. Unlabelled, [2- 13 C] and [4- 13 C]GABA concentrations were decreased in spinal cord indicating that impaired glucose metabolism contributes to hyperexcitability and supporting the use of treatments which increase GABA amounts. In conclusion, CNS glucose metabolism is compromised, while astrocytic TCA cycling appears to be normal in the hSOD1 G93A mouse model at symptomatic disease stages.

  20. Gluconeogenesis is associated with high rates of tricarboxylic acid and pyruvate cycling in fasting northern elephant seals.

    PubMed

    Champagne, Cory D; Houser, Dorian S; Fowler, Melinda A; Costa, Daniel P; Crocker, Daniel E

    2012-08-01

    Animals that endure prolonged periods of food deprivation preserve vital organ function by sparing protein from catabolism. Much of this protein sparing is achieved by reducing metabolic rate and suppressing gluconeogenesis while fasting. Northern elephant seals (Mirounga angustirostris) endure prolonged fasts of up to 3 mo at multiple life stages. During these fasts, elephant seals maintain high levels of activity and energy expenditure associated with breeding, reproduction, lactation, and development while maintaining rates of glucose production typical of a postabsorptive mammal. Therefore, we investigated how fasting elephant seals meet the requirements of glucose-dependent tissues while suppressing protein catabolism by measuring the contribution of glycogenolysis, glycerol, and phosphoenolpyruvate (PEP) to endogenous glucose production (EGP) during their natural 2-mo postweaning fast. Additionally, pathway flux rates associated with the tricarboxylic acid (TCA) cycle were measured specifically, flux through phosphoenolpyruvate carboxykinase (PEPCK) and pyruvate cycling. The rate of glucose production decreased during the fast (F(1,13) = 5.7, P = 0.04) but remained similar to that of postabsorptive mammals. The fractional contributions of glycogen, glycerol, and PEP did not change with fasting; PEP was the primary gluconeogenic precursor and accounted for ∼95% of EGP. This large contribution of PEP to glucose production occurred without substantial protein loss. Fluxes through the TCA cycle, PEPCK, and pyruvate cycling were higher than reported in other species and were the most energetically costly component of hepatic carbohydrate metabolism. The active pyruvate recycling fluxes detected in elephant seals may serve to rectify gluconeogeneic PEP production during restricted anaplerotic inflow in these fasting-adapted animals.

  1. Metabolite profiling of human colon carcinoma--deregulation of TCA cycle and amino acid turnover.

    PubMed

    Denkert, Carsten; Budczies, Jan; Weichert, Wilko; Wohlgemuth, Gert; Scholz, Martin; Kind, Tobias; Niesporek, Silvia; Noske, Aurelia; Buckendahl, Anna; Dietel, Manfred; Fiehn, Oliver

    2008-09-18

    Apart from genetic alterations, development and progression of colorectal cancer has been linked to influences from nutritional intake, hyperalimentation, and cellular metabolic changes that may be the basis for new diagnostic and therapeutic approaches. However, in contrast to genomics and proteomics, comprehensive metabolomic investigations of alterations in malignant tumors have rarely been conducted. In this study we investigated a set of paired samples of normal colon tissue and colorectal cancer tissue with gas-chromatography time-of-flight mass-spectrometry, which resulted in robust detection of a total of 206 metabolites. Metabolic phenotypes of colon cancer and normal tissues were different at a Bonferroni corrected significance level of p=0.00170 and p=0.00005 for the first two components of an unsupervised PCA analysis. Subsequent supervised analysis found 82 metabolites to be significantly different at p<0.01. Metabolites were connected to abnormalities in metabolic pathways by a new approach that calculates the distance of each pair of metabolites in the KEGG database interaction lattice. Intermediates of the TCA cycle and lipids were found down-regulated in cancer, whereas urea cycle metabolites, purines, pyrimidines and amino acids were generally found at higher levels compared to normal colon mucosa. This study demonstrates that metabolic profiling facilitates biochemical phenotyping of normal and neoplastic colon tissue at high significance levels and points to GC-TOF-based metabolomics as a new method for molecular pathology investigations.

  2. Contribution of the tricarboxylic acid (TCA) cycle and the glyoxylate shunt in Saccharomyces cerevisiae to succinic acid production during dough fermentation.

    PubMed

    Rezaei, Mohammad N; Aslankoohi, Elham; Verstrepen, Kevin J; Courtin, Christophe M

    2015-07-02

    Succinic acid produced by yeast during bread dough fermentation can significantly affect the rheological properties of the dough. By introducing mutations in the model S288C yeast strain, we show that the oxidative pathway of the TCA cycle and the glyoxylate shunt contribute significantly to succinic acid production during dough fermentation. More specifically, deletion of ACO1 and double deletion of ACO1 and ICL1 resulted in a 36 and 77% decrease in succinic acid levels in fermented dough, respectively. Similarly, double deletion of IDH1 and IDP1 decreased succinic acid production by 85%, while also affecting the fermentation rate. By contrast, double deletion of SDH1 and SDH2 resulted in a two-fold higher succinic acid accumulation compared to the wild-type. Deletion of fumarate reductase activity (FRD1 and OSM1) in the reductive pathway of the TCA cycle did not affect the fermentation rate and succinic acid production. The changes in the levels of succinic acid produced by mutants Δidh1Δidp1 (low level) and Δsdh1Δsdh2 (high level) in fermented dough only resulted in small pH differences, reflecting the buffering capacity of dough at a pH of around 5.1. Moreover, Rheofermentometer analysis using these mutants revealed no difference in maximum dough height and gas retention capacity with the dough prepared with S288C. The impact of the changed succinic acid profile on the organoleptic or antimicrobial properties of bread remains to be demonstrated. Copyright © 2015 Elsevier B.V. All rights reserved.

  3. Protein-protein interactions and metabolite channelling in the plant tricarboxylic acid cycle

    PubMed Central

    Zhang, Youjun; Beard, Katherine F. M.; Swart, Corné; Bergmann, Susan; Krahnert, Ina; Nikoloski, Zoran; Graf, Alexander; Ratcliffe, R. George; Sweetlove, Lee J.; Fernie, Alisdair R.; Obata, Toshihiro

    2017-01-01

    Protein complexes of sequential metabolic enzymes, often termed metabolons, may permit direct channelling of metabolites between the enzymes, providing increased control over metabolic pathway fluxes. Experimental evidence supporting their existence in vivo remains fragmentary. In the present study, we test binary interactions of the proteins constituting the plant tricarboxylic acid (TCA) cycle. We integrate (semi-)quantitative results from affinity purification-mass spectrometry, split-luciferase and yeast-two-hybrid assays to generate a single reliability score for assessing protein–protein interactions. By this approach, we identify 158 interactions including those between catalytic subunits of sequential enzymes and between subunits of enzymes mediating non-adjacent reactions. We reveal channelling of citrate and fumarate in isolated potato mitochondria by isotope dilution experiments. These results provide evidence for a functional TCA cycle metabolon in plants, which we discuss in the context of contemporary understanding of this pathway in other kingdoms. PMID:28508886

  4. ATCA/muTCA for Physics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jezynski, Tomasz; /DESY; Larsen, Raymond

    ATCA/{mu}TCA platforms are attractive because of the modern serial link architecture, high availability features and many packaging options. Less-demanding availability applications can be met economically by scaling back speed and redundancy. The ATCA specification was originally targeted for the Telecom industry but has gained recently a much wider user audience. The purpose of this paper is to report on present hardware and software R and D efforts where ATCA and {mu}TCA are planned, already being used or in development using selected examples for accelerator and detectors in the Physics community. It will present also the status of a proposal formore » physics extensions to ATCA/{mu}TCA specifications to promote inter-operability of laboratory and industry designs for physics.« less

  5. Synergy between (13)C-metabolic flux analysis and flux balance analysis for understanding metabolic adaptation to anaerobiosis in E. coli.

    PubMed

    Chen, Xuewen; Alonso, Ana P; Allen, Doug K; Reed, Jennifer L; Shachar-Hill, Yair

    2011-01-01

    Genome-based Flux Balance Analysis (FBA) and steady-state isotopic-labeling-based Metabolic Flux Analysis (MFA) are complimentary approaches to predicting and measuring the operation and regulation of metabolic networks. Here, genome-derived models of Escherichia coli (E. coli) metabolism were used for FBA and ¹³C-MFA analyses of aerobic and anaerobic growths of wild-type E. coli (K-12 MG1655) cells. Validated MFA flux maps reveal that the fraction of maintenance ATP consumption in total ATP production is about 14% higher under anaerobic (51.1%) than aerobic conditions (37.2%). FBA revealed that an increased ATP utilization is consumed by ATP synthase to secrete protons from fermentation. The TCA cycle is shown to be incomplete in aerobically growing cells and submaximal growth is due to limited oxidative phosphorylation. An FBA was successful in predicting product secretion rates in aerobic culture if both glucose and oxygen uptake measurement were constrained, but the most-frequently predicted values of internal fluxes yielded from sampling the feasible space differ substantially from MFA-derived fluxes. © 2010 Elsevier Inc. All rights reserved.

  6. Cycle flux algebra for ion and water flux through the KcsA channel single-file pore links microscopic trajectories and macroscopic observables.

    PubMed

    Oiki, Shigetoshi; Iwamoto, Masayuki; Sumikama, Takashi

    2011-01-31

    In narrow pore ion channels, ions and water molecules diffuse in a single-file manner and cannot pass each other. Under such constraints, ion and water fluxes are coupled, leading to experimentally observable phenomena such as the streaming potential. Analysis of this coupled flux would provide unprecedented insights into the mechanism of permeation. In this study, ion and water permeation through the KcsA potassium channel was the focus, for which an eight-state discrete-state Markov model has been proposed based on the crystal structure, exhibiting four ion-binding sites. Random transitions on the model lead to the generation of the net flux. Here we introduced the concept of cycle flux to derive exact solutions of experimental observables from the permeation model. There are multiple cyclic paths on the model, and random transitions complete the cycles. The rate of cycle completion is called the cycle flux. The net flux is generated by a combination of cyclic paths with their own cycle flux. T.L. Hill developed a graphical method of exact solutions for the cycle flux. This method was extended to calculate one-way cycle fluxes of the KcsA channel. By assigning the stoichiometric numbers for ion and water transfer to each cycle, we established a method to calculate the water-ion coupling ratio (CR(w-i)) through cycle flux algebra. These calculations predicted that CR(w-i) would increase at low potassium concentrations. One envisions an intuitive picture of permeation as random transitions among cyclic paths, and the relative contributions of the cycle fluxes afford experimental observables.

  7. Cycle Flux Algebra for Ion and Water Flux through the KcsA Channel Single-File Pore Links Microscopic Trajectories and Macroscopic Observables

    PubMed Central

    Oiki, Shigetoshi; Iwamoto, Masayuki; Sumikama, Takashi

    2011-01-01

    In narrow pore ion channels, ions and water molecules diffuse in a single-file manner and cannot pass each other. Under such constraints, ion and water fluxes are coupled, leading to experimentally observable phenomena such as the streaming potential. Analysis of this coupled flux would provide unprecedented insights into the mechanism of permeation. In this study, ion and water permeation through the KcsA potassium channel was the focus, for which an eight-state discrete-state Markov model has been proposed based on the crystal structure, exhibiting four ion-binding sites. Random transitions on the model lead to the generation of the net flux. Here we introduced the concept of cycle flux to derive exact solutions of experimental observables from the permeation model. There are multiple cyclic paths on the model, and random transitions complete the cycles. The rate of cycle completion is called the cycle flux. The net flux is generated by a combination of cyclic paths with their own cycle flux. T.L. Hill developed a graphical method of exact solutions for the cycle flux. This method was extended to calculate one-way cycle fluxes of the KcsA channel. By assigning the stoichiometric numbers for ion and water transfer to each cycle, we established a method to calculate the water-ion coupling ratio (CR w-i) through cycle flux algebra. These calculations predicted that CR w-i would increase at low potassium concentrations. One envisions an intuitive picture of permeation as random transitions among cyclic paths, and the relative contributions of the cycle fluxes afford experimental observables. PMID:21304994

  8. Analysis of Metabolic Pathways and Fluxes in a Newly Discovered Thermophilic and Ethanol-Tolerant Geobacillus Strain

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, Yinjie J.; Sapra, Rajat; Joyner, Dominique

    2009-01-20

    A recently discovered thermophilic bacterium, Geobacillus thermoglucosidasius M10EXG, ferments a range of C5 (e.g., xylose) and C6 sugars (e.g., glucose) and istolerant to high ethanol concentrations (10percent, v/v). We have investigated the central metabolism of this bacterium using both in vitro enzyme assays and 13C-based flux analysis to provide insights into the physiological properties of this extremophile and explore its metabolism for bio-ethanol or other bioprocess applications. Our findings show that glucose metabolism in G. thermoglucosidasius M10EXG proceeds via glycolysis, the pentose phosphate pathway, and the TCA cycle; the Entner?Doudoroff pathway and transhydrogenase activity were not detected. Anaplerotic reactions (includingmore » the glyoxylate shunt, pyruvate carboxylase, and phosphoenolpyruvate carboxykinase) were active, but fluxes through those pathways could not be accuratelydetermined using amino acid labeling. When growth conditions were switched from aerobic to micro-aerobic conditions, fluxes (based on a normalized glucose uptake rate of 100 units (g DCW)-1 h-1) through the TCA cycle and oxidative pentose phosphate pathway were reduced from 64+-3 to 25+-2 and from 30+-2 to 19+-2, respectively. The carbon flux under micro-aerobic growth was directed formate. Under fully anerobic conditions, G. thermoglucosidasius M10EXG used a mixed acid fermentation process and exhibited a maximum ethanol yield of 0.38+-0.07 mol mol-1 glucose. In silico flux balance modeling demonstrates that lactate and acetate production from G. thermoglucosidasius M10EXG reduces the maximum ethanol yieldby approximately threefold, thus indicating that both pathways should be modified to maximize ethanol production.« less

  9. Glutamate is the major anaplerotic substrate in the tricarboxylic acid cycle of isolated rumen epithelial and duodenal mucosal cells from beef cattle

    USDA-ARS?s Scientific Manuscript database

    This study aimed to determine the contribution of substrates to tricarboxylic acid (TCA) cycle fluxes in rumen epithelial (REC) and duodenal mucosal (DMC) cells isolated from bulls (n = 6) fed either a 75% forage (HF) or 75% concentrate (HC) diet. In separate incubations, [13C6]glucose, [13C5]glutam...

  10. MTR FAST NEUTRON FLUX MEASUREMENTS FOR CYCLE 146

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weber, L D; Hogg, C H

    1962-03-20

    The fast neutron fluxes in selected positions of the MTR were measured for Cycle 146. The measurements were made at the beginning, throughout, and at the end of the cycle (564 Mwd). Vertical traverses for each position monitors are shown. (auth)

  11. Updates to a 13C metabolic flux analysis model for evaluating energy metabolism in cultured cerebellar granule neurons from neonatal rats.

    PubMed

    Jekabsons, Mika B; Gebril, Hoda M; Wang, Yan-Hong; Avula, Bharathi; Khan, Ikhlas A

    2017-10-01

    A hexose phosphate recycling model previously developed to infer fluxes through the major glucose consuming pathways in cultured cerebellar granule neurons (CGNs) from neonatal rats metabolizing [1,2- 13 C 2 ]glucose was revised by considering reverse flux through the non-oxidative pentose phosphate pathway (PPP) and symmetrical succinate oxidation within the tricarboxylic acid (TCA) cycle. The model adjusts three flux ratios to effect 13 C distribution in the hexose, pentose, and triose phosphate pools, and in TCA cycle malate to minimize the error between predicted and measured 13 C labeling in exported lactate (i.e., unlabeled, single-, double-, and triple-labeled; M, M1, M2, and M3, respectively). Inclusion of reverse non-oxidative PPP flux substantially increased the number of calculations but ultimately had relatively minor effects on the labeling of glycolytic metabolites. From the error-minimized solution in which the predicted M-M3 lactate differed by 0.49% from that measured by liquid chromatography-triple quadrupole mass spectrometry, the neurons exhibited negligible forward non-oxidative PPP flux. Thus, no glucose was used by the pentose cycle despite explicit consideration of hexose phosphate recycling. Mitochondria consumed only 16% of glucose while 45% was exported as lactate by aerobic glycolysis. The remaining 39% of glucose was shunted to pentose phosphates presumably for de novo nucleotide synthesis, but the proportion metabolized through the oxidative PPP vs. the reverse non-oxidative PPP could not be determined. The lactate exported as M1 (2.5%) and M3 (1.2%) was attributed to malic enzyme, which was responsible for 7.8% of pyruvate production (vs. 92.2% by glycolysis). The updated model is more broadly applicable to different cell types by considering bi-directional flux through the non-oxidative PPP. Its application to cultured neurons utilizing glucose as the sole exogenous substrate has demonstrated substantial oxygen-independent glucose

  12. Differential effects of safflower oil versus fish oil feeding on insulin-stimulated glycogen synthesis, glycolysis, and pyruvate dehydrogenase flux in skeletal muscle: a 13C nuclear magnetic resonance study.

    PubMed

    Jucker, B M; Cline, G W; Barucci, N; Shulman, G I

    1999-01-01

    To examine the effects of safflower oil versus fish oil feeding on in vivo intramuscular glucose metabolism and relative pyruvate dehydrogenase (PDH) versus tricarboxylic acid (TCA) cycle flux, rats were pair-fed on diets consisting of 1) 59% safflower oil, 2) 59% menhaden fish oil, or 3) 59% carbohydrate (control) in calories. Rates of glycolysis and glycogen synthesis were assessed by monitoring [1-(13)C]glucose label incorporation into [1-(13)C]glycogen, [3-(13)C]lactate, and [3-(13)C]alanine in the hindlimb of awake rats via 13C nuclear magnetic resonance (NMR) spectroscopy during a euglycemic (approximately 6 mmol/l) hyperinsulinemic (approximately 180 microU/ml) clamp. A steady-state isotopic analysis of lactate, alanine, and glutamate was used to determine the relative PDH versus TCA cycle flux present in muscle under these conditions. The safflower oil-fed rats were insulin resistant compared with control and fish oil-fed rats, as reflected by a markedly reduced glucose infusion rate (Ginf) during the clamp (21.4 +/- 2.3 vs. 31.6 +/- 2.8 and 31.7 +/- 1.9 mg x kg(-1) x min(-1) in safflower oil versus control and fish oil groups, respectively, P < 0.006). This decrease in insulin-stimulated glucose disposal in the safflower oil group was associated with a lower rate of glycolysis (21.7 +/- 2.2 nmol x g(-1) x min(-1)) versus control (62.1 +/- 10.3 nmol x g(-1) x min(-1), P < 0.001) and versus fish oil (45.7 +/- 6.7 nmol x g(-1) x min(-1), P < 0.04), as no change in glycogen synthesis (103 +/- 15, 133 +/- 19, and 125 +/- 14 nmol x g(-1) x min(-1) in safflower oil, fish oil, and control, respectively) was detected. The intramuscular triglyceride (TG) content was increased in the safflower oil group (7.3 +/- 0.8 micromol/g) compared with the control group (5.2 +/- 0.8 micromol/g, P < 0.05) and the fish oil group (3.6 +/- 1.1 micromol/g, P < 0.01). Conversely, the percent PDH versus TCA cycle flux was decreased in the safflower oil (43 +/- 8%) versus the control

  13. In vivo detection of brain Krebs cycle intermediate by hyperpolarized magnetic resonance.

    PubMed

    Mishkovsky, Mor; Comment, Arnaud; Gruetter, Rolf

    2012-12-01

    The Krebs (or tricarboxylic acid (TCA)) cycle has a central role in the regulation of brain energy regulation and metabolism, yet brain TCA cycle intermediates have never been directly detected in vivo. This study reports the first direct in vivo observation of a TCA cycle intermediate in intact brain, namely, 2-oxoglutarate, a key biomolecule connecting metabolism to neuronal activity. Our observation reveals important information about in vivo biochemical processes hitherto considered undetectable. In particular, it provides direct evidence that transport across the inner mitochondria membrane is rate limiting in the brain. The hyperpolarized magnetic resonance protocol designed for this study opens the way to direct and real-time studies of TCA cycle kinetics.

  14. In vivo detection of brain Krebs cycle intermediate by hyperpolarized magnetic resonance

    PubMed Central

    Mishkovsky, Mor; Comment, Arnaud; Gruetter, Rolf

    2012-01-01

    The Krebs (or tricarboxylic acid (TCA)) cycle has a central role in the regulation of brain energy regulation and metabolism, yet brain TCA cycle intermediates have never been directly detected in vivo. This study reports the first direct in vivo observation of a TCA cycle intermediate in intact brain, namely, 2-oxoglutarate, a key biomolecule connecting metabolism to neuronal activity. Our observation reveals important information about in vivo biochemical processes hitherto considered undetectable. In particular, it provides direct evidence that transport across the inner mitochondria membrane is rate limiting in the brain. The hyperpolarized magnetic resonance protocol designed for this study opens the way to direct and real-time studies of TCA cycle kinetics. PMID:22990416

  15. Enzymatic mechanism of oxalate production in the TCA and glyoxylate pathways using various isolates of Antrodia radiculosa

    Treesearch

    K.M. Jenkins; S.V. Diehl; C.A. Clausen; F. Green

    2011-01-01

    Brown-rot fungi produce oxalate in large amounts; however, levels of accumulation and function vary by species. Copper-tolerant fungi, like Antrodia radiculosa, produce and accumulate high levels of oxalate in response to copper. Oxalate biosynthesis in copper-tolerant fungi has been linked to the glyoxylate and tricarboxylic acid (TCA) cycles. Within these two cycles...

  16. Metabolic flux analysis of the halophilic archaeon Haladaptatus paucihalophilus.

    PubMed

    Liu, Guangxiu; Zhang, Manxiao; Mo, Tianlu; He, Lian; Zhang, Wei; Yu, Yi; Zhang, Qi; Ding, Wei

    2015-11-27

    This work reports the (13)C-assisted metabolic flux analysis of Haladaptatus paucihalophilus, a halophilic archaeon possessing an intriguing osmoadaption mechanism. We showed that the carbon flow is through the oxidative tricarboxylic acid (TCA) cycle whereas the reductive TCA cycle is not operative in H. paucihalophilus. In addition, both threonine and the citramalate pathways contribute to isoleucine biosynthesis, whereas lysine is synthesized through the diaminopimelate pathway and not through the α-aminoadipate pathway. Unexpected, the labeling patterns of glycine from the cells grown on [1-(13)C]pyruvate and [2-(13)C]pyruvate suggest that, unlike all the organisms investigated so far, in which glycine is produced exclusively from the serine hydroxymethyltransferase (SHMT) pathway, glycine biosynthesis in H. paucihalophilus involves different pathways including SHMT, threonine aldolase (TA) and the reverse reaction of glycine cleavage system (GCS), demonstrating for the first time that other pathways instead of SHMT can also make a significant contribution to the cellular glycine pool. Transcriptional analysis confirmed that both TA and GCS genes were transcribed in H. paucihalophilus, and the transcriptional level is independent of salt concentrations in the culture media. This study expands our understanding of amino acid biosynthesis and provides valuable insights into the metabolism of halophilic archaea. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Aqueous Extract of Black Maca Prevents Metabolism Disorder via Regulating the Glycolysis/Gluconeogenesis-TCA Cycle and PPARα Signaling Activation in Golden Hamsters Fed a High-Fat, High-Fructose Diet.

    PubMed

    Wan, Wenting; Li, Hongxiang; Xiang, Jiamei; Yi, Fan; Xu, Lijia; Jiang, Baoping; Xiao, Peigen

    2018-01-01

    Maca ( Lepidium meyenii Walpers) has been used as a dietary supplement and ethnomedicine for centuries. Recently, maca has become a high profile functional food worldwide because of its multiple biological activities. This study is the first explorative research to investigate the prevention and amelioration capacity of the aqueous extract of black maca (AEM) on high-fat, high-fructose diet (HFD)-induced metabolism disorder in golden hamsters and to identify the potential mechanisms involved in these effects. For 20 weeks, 6-week-old male golden hamsters were fed the following respective diets: (1) a standard diet, (2) HFD, (3) HFD supplemented with metformin, or (4) HFD supplemented with three doses of AEM (300, 600, or 1,200 mg/kg). After 20 weeks, the golden hamsters that received daily AEM supplementation presented with the beneficial effects of improved hyperlipidemia, hyperinsulinemia, insulin resistance, and hepatic steatosis in vivo . Based on the hepatic metabolomic analysis results, alterations in metabolites associated with pathological changes were examined. A total of 194 identified metabolites were mapped to 46 relative metabolic pathways, including those of energy metabolism. In addition, via in silico profiling for secondary maca metabolites by a joint pharmacophore- and structure-based approach, a compound-target-disease network was established. The results revealed that 32 bioactive compounds in maca targeted 16 proteins involved in metabolism disorder. Considering the combined metabolomics and virtual screening results, we employed quantitative real-time PCR assays to verify the gene expression of key enzymes in the relevant pathways. AEM promoted glycolysis and inhibited gluconeogenesis via regulating the expression of key genes such as Gck and Pfkm . Moreover, AEM upregulated tricarboxylic acid (TCA) cycle flux by changing the concentrations of intermediates and increasing the mRNA levels of Aco2 , Fh , and Mdh2 . In addition, the lipid

  18. Aqueous Extract of Black Maca Prevents Metabolism Disorder via Regulating the Glycolysis/Gluconeogenesis-TCA Cycle and PPARα Signaling Activation in Golden Hamsters Fed a High-Fat, High-Fructose Diet

    PubMed Central

    Wan, Wenting; Li, Hongxiang; Xiang, Jiamei; Yi, Fan; Xu, Lijia; Jiang, Baoping; Xiao, Peigen

    2018-01-01

    Maca (Lepidium meyenii Walpers) has been used as a dietary supplement and ethnomedicine for centuries. Recently, maca has become a high profile functional food worldwide because of its multiple biological activities. This study is the first explorative research to investigate the prevention and amelioration capacity of the aqueous extract of black maca (AEM) on high-fat, high-fructose diet (HFD)-induced metabolism disorder in golden hamsters and to identify the potential mechanisms involved in these effects. For 20 weeks, 6-week-old male golden hamsters were fed the following respective diets: (1) a standard diet, (2) HFD, (3) HFD supplemented with metformin, or (4) HFD supplemented with three doses of AEM (300, 600, or 1,200 mg/kg). After 20 weeks, the golden hamsters that received daily AEM supplementation presented with the beneficial effects of improved hyperlipidemia, hyperinsulinemia, insulin resistance, and hepatic steatosis in vivo. Based on the hepatic metabolomic analysis results, alterations in metabolites associated with pathological changes were examined. A total of 194 identified metabolites were mapped to 46 relative metabolic pathways, including those of energy metabolism. In addition, via in silico profiling for secondary maca metabolites by a joint pharmacophore- and structure-based approach, a compound-target-disease network was established. The results revealed that 32 bioactive compounds in maca targeted 16 proteins involved in metabolism disorder. Considering the combined metabolomics and virtual screening results, we employed quantitative real-time PCR assays to verify the gene expression of key enzymes in the relevant pathways. AEM promoted glycolysis and inhibited gluconeogenesis via regulating the expression of key genes such as Gck and Pfkm. Moreover, AEM upregulated tricarboxylic acid (TCA) cycle flux by changing the concentrations of intermediates and increasing the mRNA levels of Aco2, Fh, and Mdh2. In addition, the lipid

  19. Integration between Glycolysis and Glutamate-Glutamine Cycle Flux May Explain Preferential Glycolytic Increase during Brain Activation, Requiring Glutamate

    PubMed Central

    Hertz, Leif; Chen, Ye

    2017-01-01

    The 1988 observation by Fox et al. (1988) that brief intense brain activation increases glycolysis (pyruvate formation from glucose) much more than oxidative metabolism has been abundantly confirmed. Specifically glycolytic increase was unexpected because the amount of ATP it generates is much smaller than that formed by subsequent oxidative metabolism of pyruvate. The present article shows that preferential glycolysis can be explained by metabolic processes associated with activation of the glutamate-glutamine cycle. The flux in this cycle, which is essential for production of transmitter glutamate and GABA, equals 75% of brain glucose utilization and each turn is associated with utilization of ~1 glucose molecule. About one half of the association between cycle flux and glucose metabolism occurs during neuronal conversion of glutamine to glutamate in a process similar to the malate-aspartate shuttle (MAS) except that glutamate is supplied from glutamine, not formed from α-ketoglutarate (αKG) as during operation of conventional MAS. Regular MAS function is triggered by one oxidative process in the cytosol during glycolysis causing NAD+ reduction to NADH. Since NADH cannot cross the mitochondrial membrane (MEM) for oxidation NAD+ is re-generated by conversion of cytosolic oxaloacetate (OAA) to malate, which enters the mitochondria for oxidation and in a cyclic process regenerates cytosolic OAA. Therefore MAS as well as the “pseudo-MAS” necessary for neuronal glutamate formation can only operate together with cytosolic reduction of NAD+ to NADH. The major process causing NAD+ reduction is glycolysis which therefore also must occur during neuronal conversion of glutamine to glutamate and may energize vesicular glutamate uptake which preferentially uses glycolytically derived energy. Another major contributor to the association between glutamate-glutamine cycle and glucose utilization is the need for astrocytic pyruvate to generate glutamate. Although some

  20. Coronal Holes and Magnetic Flux Ropes Interweaving Solar Cycles

    NASA Astrophysics Data System (ADS)

    Lowder, Chris; Yeates, Anthony; Leamon, Robert; Qiu, Jiong

    2016-10-01

    Coronal holes, dark patches observed in solar observations in extreme ultraviolet and x-ray wavelengths, provide an excellent proxy for regions of open magnetic field rooted near the photosphere. Through a multi-instrument approach, including SDO data, we are able to stitch together high resolution maps of coronal hole boundaries spanning the past two solar activity cycles. These observational results are used in conjunction with models of open magnetic field to probe physical solar parameters. Magnetic flux ropes are commonly defined as bundles of solar magnetic field lines, twisting around a common axis. Photospheric surface flows and magnetic reconnection work in conjunction to form these ropes, storing magnetic stresses until eruption. With an automated methodology to identify flux ropes within observationally driven magnetofrictional simulations, we can study their properties in detail. Of particular interest is a solar-cycle length statistical description of eruption rates, spatial distribution, magnetic orientation, flux, and helicity. Coronal hole observations can provide useful data about the distribution of the fast solar wind, with magnetic flux ropes yielding clues as to ejected magnetic field and the resulting space weather geo-effectiveness. With both of these cycle-spanning datasets, we can begin to form a more detailed picture of the evolution and consequences of both sets of solar magnetic features.

  1. The pentose phosphate pathway leads to enhanced succinic acid flux in biofilms of wild-type Actinobacillus succinogenes.

    PubMed

    Bradfield, Michael F A; Nicol, Willie

    2016-11-01

    Increased pentose phosphate pathway flux, relative to total substrate uptake flux, is shown to enhance succinic acid (SA) yields under continuous, non-growth conditions of Actinobacillus succinogenes biofilms. Separate fermentations of glucose and xylose were conducted in a custom, continuous biofilm reactor at four different dilution rates. Glucose-6-phosphate dehydrogenase assays were performed on cell extracts derived from in situ removal of biofilm at each steady state. The results of the assays were coupled to a kinetic model that revealed an increase in oxidative pentose phosphate pathway (OPPP) flux relative to total substrate flux with increasing SA titre, for both substrates. Furthermore, applying metabolite concentration data to metabolic flux models that include the OPPP revealed similar flux relationships to those observed in the experimental kinetic analysis. A relative increase in OPPP flux produces additional reduction power that enables increased flux through the reductive branch of the TCA cycle, leading to increased SA yields, reduced by-product formation and complete closure of the overall redox balance.

  2. Bidirectionality and compartmentation of metabolic fluxes are revealed in the dynamics of isotopomer networks.

    PubMed

    Schryer, David W; Peterson, Pearu; Paalme, Toomas; Vendelin, Marko

    2009-04-17

    Isotope labeling is one of the few methods of revealing the in vivo bidirectionality and compartmentalization of metabolic fluxes within metabolic networks. We argue that a shift from steady state to dynamic isotopomer analysis is required to deal with these cellular complexities and provide a review of dynamic studies of compartmentalized energy fluxes in eukaryotic cells including cardiac muscle, plants, and astrocytes. Knowledge of complex metabolic behaviour on a molecular level is prerequisite for the intelligent design of genetically modified organisms able to realize their potential of revolutionizing food, energy, and pharmaceutical production. We describe techniques to explore the bidirectionality and compartmentalization of metabolic fluxes using information contained in the isotopic transient, and discuss the integration of kinetic models with MFA. The flux parameters of an example metabolic network were optimized to examine the compartmentalization of metabolites and and the bidirectionality of fluxes in the TCA cycle of Saccharomyces uvarum for steady-state respiratory growth.

  3. Using a Magnetic Flux Transport Model to Predict the Solar Cycle

    NASA Technical Reports Server (NTRS)

    Lyatskaya, S.; Hathaway, D.; Winebarger, A.

    2007-01-01

    We present the results of an investigation into the use of a magnetic flux transport model to predict the amplitude of future solar cycles. Recently Dikpati, de Toma, & Gilman (2006) showed how their dynamo model could be used to accurately predict the amplitudes of the last eight solar cycles and offered a prediction for the next solar cycle - a large amplitude cycle. Cameron & Schussler (2007) found that they could reproduce this predictive skill with a simple 1-dimensional surface flux transport model - provided they used the same parameters and data as Dikpati, de Toma, & Gilman. However, when they tried incorporating the data in what they argued was a more realistic manner, they found that the predictive skill dropped dramatically. We have written our own code for examining this problem and have incorporated updated and corrected data for the source terms - the emergence of magnetic flux in active regions. We present both the model itself and our results from it - in particular our tests of its effectiveness at predicting solar cycles.

  4. The Krebs Uric Acid Cycle: A Forgotten Krebs Cycle.

    PubMed

    Salway, Jack G

    2018-05-25

    Hans Kornberg wrote a paper entitled 'Krebs and his trinity of cycles' commenting that every school biology student knows of the Krebs cycle, but few know that Krebs discovered two other cycles. These are (i) the ornithine cycle (urea cycle), (ii) the citric acid cycle (tricarboxylic acid or TCA cycle), and (iii) the glyoxylate cycle that was described by Krebs and Kornberg. Ironically, Kornberg, codiscoverer of the 'glyoxylate cycle', overlooked a fourth Krebs cycle - (iv) the uric acid cycle. Copyright © 2018 Elsevier Ltd. All rights reserved.

  5. Mitochondria-Translocated PGK1 Functions as a Protein Kinase to Coordinate Glycolysis and the TCA Cycle in Tumorigenesis.

    PubMed

    Li, Xinjian; Jiang, Yuhui; Meisenhelder, Jill; Yang, Weiwei; Hawke, David H; Zheng, Yanhua; Xia, Yan; Aldape, Kenneth; He, Jie; Hunter, Tony; Wang, Liwei; Lu, Zhimin

    2016-03-03

    It is unclear how the Warburg effect that exemplifies enhanced glycolysis in the cytosol is coordinated with suppressed mitochondrial pyruvate metabolism. We demonstrate here that hypoxia, EGFR activation, and expression of K-Ras G12V and B-Raf V600E induce mitochondrial translocation of phosphoglycerate kinase 1 (PGK1); this is mediated by ERK-dependent PGK1 S203 phosphorylation and subsequent PIN1-mediated cis-trans isomerization. Mitochondrial PGK1 acts as a protein kinase to phosphorylate pyruvate dehydrogenase kinase 1 (PDHK1) at T338, which activates PDHK1 to phosphorylate and inhibit the pyruvate dehydrogenase (PDH) complex. This reduces mitochondrial pyruvate utilization, suppresses reactive oxygen species production, increases lactate production, and promotes brain tumorigenesis. Furthermore, PGK1 S203 and PDHK1 T338 phosphorylation levels correlate with PDH S293 inactivating phosphorylation levels and poor prognosis in glioblastoma patients. This work highlights that PGK1 acts as a protein kinase in coordinating glycolysis and the tricarboxylic acid (TCA) cycle, which is instrumental in cancer metabolism and tumorigenesis. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. ON POLAR MAGNETIC FIELD REVERSAL AND SURFACE FLUX TRANSPORT DURING SOLAR CYCLE 24

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sun, Xudong; Todd Hoeksema, J.; Liu, Yang

    As each solar cycle progresses, remnant magnetic flux from active regions (ARs) migrates poleward to cancel the old-cycle polar field. We describe this polarity reversal process during Cycle 24 using four years (2010.33-2014.33) of line-of-sight magnetic field measurements from the Helioseismic and Magnetic Imager. The total flux associated with ARs reached maximum in the north in 2011, more than two years earlier than the south; the maximum is significantly weaker than Cycle 23. The process of polar field reversal is relatively slow, north-south asymmetric, and episodic. We estimate that the global axial dipole changed sign in 2013 October; the northernmore » and southern polar fields (mean above 60° latitude) reversed in 2012 November and 2014 March, respectively, about 16 months apart. Notably, the poleward surges of flux in each hemisphere alternated in polarity, giving rise to multiple reversals in the north. We show that the surges of the trailing sunspot polarity tend to correspond to normal mean AR tilt, higher total AR flux, or slower mid-latitude near-surface meridional flow, while exceptions occur during low magnetic activity. In particular, the AR flux and the mid-latitude poleward flow speed exhibit a clear anti-correlation. We discuss how these features can be explained in a surface flux transport process that includes a field-dependent converging flow toward the ARs, a characteristic that may contribute to solar cycle variability.« less

  7. Effects of tretinoin pretreatment on TCA chemical peel in guinea pig skin.

    PubMed Central

    Kim, I. H.; Kim, H. K.; Kye, Y. C.

    1996-01-01

    This study was done to characterize the structural changes in the tretinoin pretreatment on trichloroacetic acid(TCA) chemical peel. In guinea pigs, the right halves pretreated with tretinoin and the left halves treated nothing were compared in their structural changes after TCA chemical peel. Epidermal thickness in the tretinoin pretreated group was almost the same in the first and second week. But epidermis of the TCA group increased continuously. In the first week, mitotic figures in the epidermis were more increased in the TCA group, but those in hair follicles were more increased in the tretinoin pretreated group. In the second week, mitotic figures in the epidermis were almost same in both group, but in hair follicles of the tretinoin pretreated group, mitotic figures were much more increased. In alcian blue staining, glycosaminoglycan was stained much more strongly in dermis of the TCA group in first week, but was more strongly stained in the tretinoin pretreated group in second week. On electron microscopic findings, the fibroblasts in upper dermis were larger and had plentier cytoplasm with more organelles in the tretinoin pretreated group. Conclusively, tretinoin pretreatment on TCA chemical peel sustained the effects of TCA longer and showed synergistic effects of TCA and induced enhanced wound healing. PMID:8878803

  8. Isotopically Nonstationary Metabolic Flux Analysis (INST-MFA) of Photosynthesis and Photorespiration in Plants.

    PubMed

    Ma, Fangfang; Jazmin, Lara J; Young, Jamey D; Allen, Doug K

    2017-01-01

    Photorespiration is a central component of photosynthesis; however to better understand its role it should be viewed in the context of an integrated metabolic network rather than a series of individual reactions that operate independently. Isotopically nonstationary 13 C metabolic flux analysis (INST-MFA), which is based on transient labeling studies at metabolic steady state, offers a comprehensive platform to quantify plant central metabolism. In this chapter, we describe the application of INST-MFA to investigate metabolism in leaves. Leaves are an autotrophic tissue, assimilating CO 2 over a diurnal period implying that the metabolic steady state is limited to less than 12 h and thus requiring an INST-MFA approach. This strategy results in a comprehensive unified description of photorespiration, Calvin cycle, sucrose and starch synthesis, tricarboxylic acid (TCA) cycle, and amino acid biosynthetic fluxes. We present protocols of the experimental aspects for labeling studies: transient 13 CO 2 labeling of leaf tissue, sample quenching and extraction, mass spectrometry (MS) analysis of isotopic labeling data, measurement of sucrose and amino acids in vascular exudates, and provide details on the computational flux estimation using INST-MFA.

  9. Teaching about citric acid cycle using plant mitochondrial preparations: Some assays for use in laboratory courses*.

    PubMed

    Vicente, Joaquim A F; Gomes-Santos, Carina S S; Sousa, Ana Paula M; Madeira, Vítor M C

    2005-03-01

    Potato tubers and turnip roots were used to prepare purified mitochondria for laboratory practical work in the teaching of the citric acid cycle (TCA cycle). Plant mitochondria are particularly advantageous over the animal fractions to demonstrate the TCA cycle enzymatic steps, by using simple techniques to measure O(2) consumption and transmembrane potential (ΔΨ). The several TCA cycle intermediates induce specific enzyme activities, which can be identified by respiratory parameters. Such a strategy is also used to evidence properties of the TCA cycle enzymes: ADP stimulation of isocitrate dehydrogenase and α-ketoglutarate dehydrogenase; activation by citrate of downstream oxidation steps, e.g. succinate dehydrogenase; and regulation of the activity of isocitrate dehydrogenase by citrate action on the citrate/isocitrate carrier. Furthermore, it has been demonstrated that, in the absence of exogenous Mg(2+) , isocitrate-dependent respiration favors the alternative oxidase pathway, as judged by changes of the ADP/O elicited by the inhibitor n-propyl galate. These are some examples of assays related with TCA cycle intermediates we can use in laboratory courses. Copyright © 2005 International Union of Biochemistry and Molecular Biology, Inc.

  10. Viscous Design of TCA Configuration

    NASA Technical Reports Server (NTRS)

    Krist, Steven E.; Bauer, Steven X. S.; Campbell, Richard L.

    1999-01-01

    The goal in this effort is to redesign the baseline TCA configuration for improved performance at both supersonic and transonic cruise. Viscous analyses are conducted with OVERFLOW, a Navier-Stokes code for overset grids, using PEGSUS to compute the interpolations between overset grids. Viscous designs are conducted with OVERDISC, a script which couples OVERFLOW with the Constrained Direct Iterative Surface Curvature (CDISC) inverse design method. The successful execution of any computational fluid dynamics (CFD) based aerodynamic design method for complex configurations requires an efficient method for regenerating the computational grids to account for modifications to the configuration shape. The first section of this presentation deals with the automated regridding procedure used to generate overset grids for the fuselage/wing/diverter/nacelle configurations analysed in this effort. The second section outlines the procedures utilized to conduct OVERDISC inverse designs. The third section briefly covers the work conducted by Dick Campbell, in which a dual-point design at Mach 2.4 and 0.9 was attempted using OVERDISC; the initial configuration from which this design effort was started is an early version of the optimized shape for the TCA configuration developed by the Boeing Commercial Airplane Group (BCAG), which eventually evolved into the NCV design. The final section presents results from application of the Natural Flow Wing design philosophy to the TCA configuration.

  11. Cyanobacterial carbon metabolism: Fluxome plasticity and oxygen dependence: Cyanobacterial Carbon Metabolism

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wan, Ni; DeLorenzo, Drew M.; He, Lian

    Synechocystis sp. strain PCC 6803 has been widely used as a photo-biorefinery chassis. Based on its genome annotation, this species contains a complete TCA cycle, an Embden-Meyerhof-Parnas pathway (EMPP), an oxidative pentose phosphate pathway (OPPP), and an Entner–Doudoroff pathway (EDP). To evaluate how Synechocystis 6803 catabolizes glucose under heterotrophic conditions, we performed 13C metabolic flux analysis, metabolite pool size analysis, gene knockouts, and heterologous expressions. The results revealed a cyclic mode of flux through the OPPP. Small, but non-zero, fluxes were observed through the TCA cycle and the malic shunt. Independent knockouts of 6-phosphogluconate dehydrogenase (gnd) and malic enzyme (me)more » corroborated these results, as neither mutant could grow under dark heterotrophic conditions. Our data also indicate that Synechocystis 6803 metabolism relies upon oxidative phosphorylation to generate ATP from NADPH under dark or insufficient light conditions. The pool sizes of intermediates in the TCA cycle, particularly acetyl-CoA, were found to be several fold lower in Synechocystis 6803 (compared to E. coli metabolite pool sizes), while its sugar phosphate intermediates were several-fold higher. Moreover, negligible flux was detected through the native, or heterologous, EDP in the wild type or Δgnd strains under heterotrophic conditions. Comparing photoautotrophic, photomixotrophic, and heterotrophic conditions, the Calvin cycle, OPPP, and EMPP in Synechocystis 6803 possess the ability to regulate their fluxes under various growth conditions (plastic), whereas its TCA cycle always maintains at low levels (rigid). This work also demonstrates how genetic profiles do not always reflect actual metabolic flux through native or heterologous pathways. Biotechnol. Bioeng. 2017;114: 1593–1602. © 2017 Wiley Periodicals, Inc.« less

  12. Linked cycles of oxidative decarboxylation of glyoxylate as protometabolic analogs of the citric acid cycle.

    PubMed

    Springsteen, Greg; Yerabolu, Jayasudhan Reddy; Nelson, Julia; Rhea, Chandler Joel; Krishnamurthy, Ramanarayanan

    2018-01-08

    The development of metabolic approaches towards understanding the origins of life, which have focused mainly on the citric acid (TCA) cycle, have languished-primarily due to a lack of experimentally demonstrable and sustainable cycle(s) of reactions. We show here the existence of a protometabolic analog of the TCA involving two linked cycles, which convert glyoxylate into CO 2 and produce aspartic acid in the presence of ammonia. The reactions proceed from either pyruvate, oxaloacetate or malonate in the presence of glyoxylate as the carbon source and hydrogen peroxide as the oxidant under neutral aqueous conditions and at mild temperatures. The reaction pathway demonstrates turnover under controlled conditions. These results indicate that simpler versions of metabolic cycles could have emerged under potential prebiotic conditions, laying the foundation for the appearance of more sophisticated metabolic pathways once control by (polymeric) catalysts became available.

  13. The antidiabetic drug metformin decreases mitochondrial respiration and tricarboxylic acid cycle activity in cultured primary rat astrocytes.

    PubMed

    Hohnholt, Michaela C; Blumrich, Eva-Maria; Waagepetersen, Helle S; Dringen, Ralf

    2017-11-01

    Metformin is an antidiabetic drug that is used daily by millions of patients worldwide. Metformin is able to cross the blood-brain barrier and has recently been shown to increase glucose consumption and lactate release in cultured astrocytes. However, potential effects of metformin on mitochondrial tricarboxylic acid (TCA) cycle metabolism in astrocytes are unknown. We investigated this by mapping 13 C labeling in TCA cycle intermediates and corresponding amino acids after incubation of primary rat astrocytes with [U- 13 C]glucose. The presence of metformin did not compromise the viability of cultured astrocytes during 4 hr of incubation, but almost doubled cellular glucose consumption and lactate release. Compared with control cells, the presence of metformin dramatically lowered the molecular 13 C carbon labeling (MCL) of the cellular TCA cycle intermediates citrate, α-ketoglutarate, succinate, fumarate, and malate, as well as the MCL of the TCA cycle intermediate-derived amino acids glutamate, glutamine, and aspartate. In addition to the total molecular 13 C labeling, analysis of the individual isotopomers of TCA cycle intermediates confirmed a severe decline in labeling and a significant lowering in TCA cycling ratio in metformin-treated astrocytes. Finally, the oxygen consumption of mitochondria isolated from metformin-treated astrocytes was drastically reduced in the presence of complex I substrates, but not of complex II substrates. These data demonstrate that exposure to metformin strongly impairs complex I-mediated mitochondrial respiration in astrocytes, which is likely to cause the observed decrease in labeling of mitochondrial TCA cycle intermediates and the stimulation of glycolytic lactate production. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Metabolic flux analysis of heterotrophic growth in Chlamydomonas reinhardtii.

    PubMed

    Boyle, Nanette R; Sengupta, Neelanjan; Morgan, John A

    2017-01-01

    Despite the wealth of knowledge available for C. reinhardtii, the central metabolic fluxes of growth on acetate have not yet been determined. In this study, 13C-metabolic flux analysis (13C-MFA) was used to determine and quantify the metabolic pathways of primary metabolism in C. reinhardtii cells grown under heterotrophic conditions with acetate as the sole carbon source. Isotopic labeling patterns of compartment specific biomass derived metabolites were used to calculate the fluxes. It was found that acetate is ligated with coenzyme A in the three subcellular compartments (cytosol, mitochondria and plastid) included in the model. Two citrate synthases were found to potentially be involved in acetyl-coA metabolism; one localized in the mitochondria and the other acting outside the mitochondria. Labeling patterns demonstrate that Acetyl-coA synthesized in the plastid is directly incorporated in synthesis of fatty acids. Despite having a complete TCA cycle in the mitochondria, it was also found that a majority of the malate flux is shuttled to the cytosol and plastid where it is converted to oxaloacetate providing reducing equivalents to these compartments. When compared to predictions by flux balance analysis, fluxes measured with 13C-MFA were found to be suboptimal with respect to biomass yield; C. reinhardtii sacrifices biomass yield to produce ATP and reducing equivalents.

  15. Redistribution of carbon flux in Torulopsis glabrata by altering vitamin and calcium level.

    PubMed

    Liu, Liming; Li, Yin; Zhu, Yang; Du, Guocheng; Chen, Jian

    2007-01-01

    Manipulation of cofactor (thiamine, biotin and Ca(2+)) levels as a potential tool to redistribute carbon flux was studied in Torulopsis glabrata. With sub-optimization of vitamin in fermentation medium, the carbon flux was blocked at the key node of pyruvate, and 69 g/L pyruvate was accumulated. Increasing the concentrations of thiamine and biotin could selectively open the valve of carbon flux from pyruvate to pyruvate dehydrogenase complex, the pyruvate carboxylase (PC) pathway and the channel into the TCA cycle, leading to the over-production of alpha-ketoglutarate. In addition, the activity of PC was enhanced with Ca(2+) present in fermentation medium. By combining high concentration's vitamins and CaCO(3) as the pH buffer, a batch culture was conducted in a 7-L fermentor, with the pyruvate concentration decreased to 21.8 g/L while alpha-ketoglutarate concentration increased to 43.7 g/L. Our study indicated that the metabolic flux could be redistributed to overproduce desired metabolites with manipulating the cofactor levels. Furthermore, the manipulation of vitamin level provided an alternative tool to realize metabolic engineering goals.

  16. Sulfate radicals enable a non-enzymatic Krebs cycle precursor

    PubMed Central

    Keller, Markus A.; Kampjut, Domen; Harrison, Stuart A.; Ralser, Markus

    2017-01-01

    The evolutionary origins of the tricarboxylic acid cycle (TCA), or Krebs cycle, are so far unclear. Despite a few years ago, the existence of a simple non-enzymatic Krebs-cycle catalyst has been dismissed ‘as an appeal to magic’, citrate and other intermediates have meanwhile been discovered on a carbonaceous meteorite and do interconvert non-enzymatically. To identify the non-enzymatic Krebs cycle catalyst, we used combinatorial, quantitative high-throughput metabolomics to systematically screen iron and sulfate reaction milieus that orient on Archean sediment constituents. TCA cycle intermediates are found stable in water and in the presence of most iron and sulfate species, including simple iron-sulfate minerals. However, we report that TCA intermediates undergo 24 interconversion reactions in the presence of sulfate radicals that form from peroxydisulfate. The non-enzymatic reactions critically cover a topology as present in the Krebs cycle, the glyoxylate shunt and the succinic semialdehyde pathways. Assembled in a chemical network, the reactions achieve more than ninety percent carbon recovery. Our results show that a non-enzymatic precursor for the Krebs cycle is biologically sensible, efficient, and forms spontaneously in the presence of sulfate radicals. PMID:28584880

  17. Gluconeogenesis from labeled carbon: estimating isotope dilution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kelleher, J.K.

    1986-03-01

    To estimate the rate of gluconeogenesis from steady-state incorporation of labeled 3-carbon precursors into glucose, isotope dilution must be considered so that the rate of labeling of glucose can be quantitatively converted to the rate of gluconeogenesis. An expression for the value of this isotope dilution can be derived using mathematical techniques and a model of the tricarboxylic acid (TCA) cycle. The present investigation employs a more complex model than that used in previous studies. This model includes the following pathways that may affect the correction for isotope dilution: 1) flux of 3-carbon precursor to the oxaloacetate pool via acetyl-CoAmore » and the TCA cycle; 2) flux of 4- or 5-carbon compounds into the TCA cycle; 3) reversible flux between oxaloacetate (OAA) and pyruvate and between OAA and fumarate; 4) incomplete equilibrium between OAA pools; and 5) isotope dilution of 3-carbon tracers between the experimentally measured pool and the precursor for the TCA-cycle OAA pool. Experimental tests are outlined which investigators can use to determine whether these pathways are significant in a specific steady-state system. The study indicated that flux through these five pathways can significantly affect the correction for isotope dilution. To correct for the effects of these pathways an alternative method for calculating isotope dilution is proposed using citrate to relate the specific activities of acetyl-CoA and OAA.« less

  18. Quantitative importance of the pentose phosphate pathway determined by incorporation of 13C from [2-13C]- and [3-13C]glucose into TCA cycle intermediates and neurotransmitter amino acids in functionally intact neurons.

    PubMed

    Brekke, Eva M F; Walls, Anne B; Schousboe, Arne; Waagepetersen, Helle S; Sonnewald, Ursula

    2012-09-01

    The brain is highly susceptible to oxidative injury, and the pentose phosphate pathway (PPP) has been shown to be affected by pathological conditions, such as Alzheimer's disease and traumatic brain injury. While this pathway has been investigated in the intact brain and in astrocytes, little is known about the PPP in neurons. The activity of the PPP was quantified in cultured cerebral cortical and cerebellar neurons after incubation in the presence of [2-(13)C]glucose or [3-(13)C]glucose. The activity of the PPP was several fold lower than glycolysis in both types of neurons. While metabolism of (13)C-labeled glucose via the PPP does not appear to contribute to the production of releasable lactate, it contributes to labeling of tricarboxylic acid (TCA) cycle intermediates and related amino acids. Based on glutamate isotopomers, it was calculated that PPP activity accounts for ~6% of glucose metabolism in cortical neurons and ~4% in cerebellar neurons. This is the first demonstration that pyruvate generated from glucose via the PPP contributes to the synthesis of acetyl CoA for oxidation in the TCA cycle. Moreover, the fact that (13)C labeling from glucose is incorporated into glutamate proves that both the oxidative and the nonoxidative stages of the PPP are active in neurons.

  19. Computational exploration of the chemical structure space of possible reverse tricarboxylic acid cycle constituents.

    PubMed

    Meringer, Markus; Cleaves, H James

    2017-12-13

    The reverse tricarboxylic acid (rTCA) cycle has been explored from various standpoints as an idealized primordial metabolic cycle. Its simplicity and apparent ubiquity in diverse organisms across the tree of life have been used to argue for its antiquity and its optimality. In 2000 it was proposed that chemoinformatics approaches support some of these views. Specifically, defined queries of the Beilstein database showed that the molecules of the rTCA are heavily represented in such compound databases. We explore here the chemical structure "space," e.g. the set of organic compounds which possesses some minimal set of defining characteristics, of the rTCA cycle's intermediates using an exhaustive structure generation method. The rTCA's chemical space as defined by the original criteria and explored by our method is some six to seven times larger than originally considered. Acknowledging that each assumption in what is a defining criterion making the rTCA cycle special limits possible generative outcomes, there are many unrealized compounds which fulfill these criteria. That these compounds are unrealized could be due to evolutionary frozen accidents or optimization, though this optimization may also be for systems-level reasons, e.g., the way the pathway and its elements interface with other aspects of metabolism.

  20. Quantum chemical study, spectroscopic investigations, NBO and HOMO-LUMO analyses of 3-aminoquinoline (3AQ) and [Ag(3AQ)2(TCA)] complex (TCA = Trichloroacetate)

    NASA Astrophysics Data System (ADS)

    Soliman, Saied M.; Kassem, Taher S.; Badr, Ahmed M. A.; Abu Youssef, Morsy A.; Assem, Rania

    2014-09-01

    The new [Ag(3AQ)2(TCA)]; (3AQ = 3-aminoquinoline and TCA = Trichloroacetate) complex is synthesized and characterized using elemental analysis, FTIR, NMR and mass spectroscopy. The molecular geometry, vibrational frequencies, gauge-including atomic orbital (GIAO) 1H chemical shift values of the free and coordinated 3AQ in the ground state have been calculated by using DFT/B3LYP method. The TD-DFT results of the [Ag(3AQ)2(TCA)] complex showed a π-π* transition band at 240.3-242.6 nm (f = 0.1334-0.1348) which has longer wavelength and lower absorption intensity than that for the free 3AQ (233.2 nm, f = 0.3958). Dipole moment, polarizability and HOMO-LUMO gap values predicted better nonlinear optical properties (NLO) for the [Ag(3AQ)2(TCA)] than the 3AQ ligand. NBO analysis has been used to predict the most accurate Lewis structure of the studied molecules. The energies of the different intramolecular charge transfer (ICT) interactions within the studied molecules were estimated using second order perturbation theory.

  1. Global Flux Balance in the Terrestrial H2O Cycle: Reconsidering the Post-Arc Subducted H2O Flux

    NASA Astrophysics Data System (ADS)

    Parai, R.; Mukhopadhyay, S.

    2010-12-01

    Quantitative estimates of H2O fluxes between the mantle and the exosphere (i.e., the atmosphere, oceans and crust) are critical to our understanding of the chemistry and dynamics of the solid Earth: the abundance and distribution of water in the mantle has dramatic impacts upon mantle melting, degassing history, structure and style of convection. Water is outgassed from the mantle is association with volcanism at mid-ocean ridges, ocean islands and convergent margins. H2O is removed from the exosphere at subduction zones, and some fraction of the subducted flux may be recycled past the arc into the Earth’s deep interior. Estimates of the post-arc subducted H2O flux are primarily based on the stability of hydrous phases at subduction zone pressures and temperatures (e.g. Schmidt and Poli, 1998; Rüpke et al., 2004; Hacker, 2008). However, the post-arc H2O flux remains poorly quantified, in part due to large uncertainties in the water content of the subducting slab. Here we evaluate estimated post-arc subducted fluxes in the context of mantle-exosphere water cycling, using a Monte Carlo simulation of the global H2O cycle. Literature estimates of primary magmatic H2O abundances and magmatic production rates at different tectonic settings are used with estimates of the total subducted H2O flux to establish the parameter space under consideration. Random sampling of the allowed parameter space affords insight into which input and output fluxes satisfy basic constraints on global flux balance, such as a limit on sea-level change over time. The net flux of H2O between mantle and exosphere is determined by the total mantle output flux (via ridges and ocean islands, with a small contribution from mantle-derived arc output) and the input flux subducted beyond the arc. Arc and back-arc output is derived mainly from the slab, and therefore cancels out a fraction of the trench intake in an H2O subcycle. Limits on sea-level change since the end of the Archaean place

  2. The Tricarboxylic Acid Cycle, an Ancient Metabolic Network with a Novel Twist

    PubMed Central

    Mailloux, Ryan J.; Bériault, Robin; Lemire, Joseph; Singh, Ranji; Chénier, Daniel R.; Hamel, Robert D.; Appanna, Vasu D.

    2007-01-01

    The tricarboxylic acid (TCA) cycle is an essential metabolic network in all oxidative organisms and provides precursors for anabolic processes and reducing factors (NADH and FADH2) that drive the generation of energy. Here, we show that this metabolic network is also an integral part of the oxidative defence machinery in living organisms and α-ketoglutarate (KG) is a key participant in the detoxification of reactive oxygen species (ROS). Its utilization as an anti-oxidant can effectively diminish ROS and curtail the formation of NADH, a situation that further impedes the release of ROS via oxidative phosphorylation. Thus, the increased production of KG mediated by NADP-dependent isocitrate dehydrogenase (NADP-ICDH) and its decreased utilization via the TCA cycle confer a unique strategy to modulate the cellular redox environment. Activities of α-ketoglutarate dehydrogenase (KGDH), NAD-dependent isocitrate dehydrogenase (NAD-ICDH), and succinate dehydrogenase (SDH) were sharply diminished in the cellular systems exposed to conditions conducive to oxidative stress. These findings uncover an intricate link between TCA cycle and ROS homeostasis and may help explain the ineffective TCA cycle that characterizes various pathological conditions and ageing. PMID:17668068

  3. Evaluation results of xTCA equipment for HEP experiments at CERN

    NASA Astrophysics Data System (ADS)

    Di Cosmo, M.; Bobillier, V.; Haas, S.; Joos, M.; Mico, S.; Vasey, F.; Vichoudis, P.

    2013-12-01

    The MicroTCA and AdvancedTCA industry standards are candidate modular electronic platforms for the upgrade of the current generation of high energy physics experiments. The PH-ESE group at CERN launched in 2011 the xTCA evaluation project with the aim of performing technical evaluations and eventually providing support for commercially available components. Different devices from different vendors have been acquired, evaluated and interoperability tests have been performed. This paper presents the test procedures and facilities that have been developed and focuses on the evaluation results including electrical, thermal and interoperability aspects.

  4. In Folio Respiratory Fluxomics Revealed by 13C Isotopic Labeling and H/D Isotope Effects Highlight the Noncyclic Nature of the Tricarboxylic Acid “Cycle” in Illuminated Leaves1[W

    PubMed Central

    Tcherkez, Guillaume; Mahé, Aline; Gauthier, Paul; Mauve, Caroline; Gout, Elizabeth; Bligny, Richard; Cornic, Gabriel; Hodges, Michael

    2009-01-01

    While the possible importance of the tricarboxylic acid (TCA) cycle reactions for leaf photosynthesis operation has been recognized, many uncertainties remain on whether TCA cycle biochemistry is similar in the light compared with the dark. It is widely accepted that leaf day respiration and the metabolic commitment to TCA decarboxylation are down-regulated in illuminated leaves. However, the metabolic basis (i.e. the limiting steps involved in such a down-regulation) is not well known. Here, we investigated the in vivo metabolic fluxes of individual reactions of the TCA cycle by developing two isotopic methods, 13C tracing and fluxomics and the use of H/D isotope effects, with Xanthium strumarium leaves. We provide evidence that the TCA “cycle” does not work in the forward direction like a proper cycle but, rather, operates in both the reverse and forward directions to produce fumarate and glutamate, respectively. Such a functional division of the cycle plausibly reflects the compromise between two contrasted forces: (1) the feedback inhibition by NADH and ATP on TCA enzymes in the light, and (2) the need to provide pH-buffering organic acids and carbon skeletons for nitrate absorption and assimilation. PMID:19675152

  5. Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease.

    PubMed

    Sunny, Nishanth E; Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J; Nautiyal, Manisha; Mathew, Justin T; Williams, Caroline M; Cusi, Kenneth

    2015-08-15

    Elevated plasma branched-chain amino acids (BCAA) in the setting of insulin resistance have been relevant in predicting type 2 diabetes mellitus (T2DM) onset, but their role in the etiology of hepatic insulin resistance remains uncertain. We determined the link between BCAA and dysfunctional hepatic tricarboxylic acid (TCA) cycle, which is a central feature of hepatic insulin resistance and nonalcoholic fatty liver disease (NAFLD). Plasma metabolites under basal fasting and euglycemic hyperinsulinemic clamps (insulin stimulation) were measured in 94 human subjects with varying degrees of insulin sensitivity to identify their relationships with insulin resistance. Furthermore, the impact of elevated BCAA on hepatic TCA cycle was determined in a diet-induced mouse model of NAFLD, utilizing targeted metabolomics and nuclear magnetic resonance (NMR)-based metabolic flux analysis. Insulin stimulation revealed robust relationships between human plasma BCAA and indices of insulin resistance, indicating chronic metabolic overload from BCAA. Human plasma BCAA and long-chain acylcarnitines also showed a positive correlation, suggesting modulation of mitochondrial metabolism by BCAA. Concurrently, mice with NAFLD failed to optimally induce hepatic mTORC1, plasma ketones, and hepatic long-chain acylcarnitines, following acute elevation of plasma BCAA. Furthermore, elevated BCAA failed to induce multiple fluxes through hepatic TCA cycle in mice with NAFLD. Our data suggest that BCAA are essential to mediate efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of BCAA-mediated upregulation of the TCA cycle could be a significant contributor to mitochondrial dysfunction in NAFLD.

  6. The solar cycle variation of coronal mass ejections and the solar wind mass flux

    NASA Technical Reports Server (NTRS)

    Webb, David F.; Howard, Russell A.

    1994-01-01

    Coronal mass ejections (CMEs) are an important aspect of coronal physics and a potentially significant contributor to perturbations of the solar wind, such as its mass flux. Sufficient data on CMEs are now available to permit study of their longer-term occurrency patterns. Here we present the results of a study of CME occurrence rates over more than a complete 11-year solar sunspot cycle and a comparison of these rates with those of other activity related to CMEs and with the solar wind particle flux at 1 AU. The study includes an evaluation of correlations to the CME rates, which include instrument duty cycles, visibility functions, mass detection thresholds, and geometrical considerations. The main results are as follows: (1) The frequency of occurrence of CMEs tends to track the solar activity cycle in both amplitude and phase; (2) the CME rates from different instruments, when corrected for both duty cycles and visibility functions, are reasonably consistent; (3) considering only longer-term averages, no one class of solar activity is better correlated with CME rate than any other; (4) the ratio of the annualized CME to solar wind mass flux tends to track the solar cycle; and (5) near solar maximum, CMEs can provide a significant fraction (i.e., approximately equals 15%) of the average mass flux to the near-ecliptic solar wind.

  7. Quantitative importance of the pentose phosphate pathway determined by incorporation of 13C from [2-13C]- and [3-13C]glucose into TCA cycle intermediates and neurotransmitter amino acids in functionally intact neurons

    PubMed Central

    Brekke, Eva M F; Walls, Anne B; Schousboe, Arne; Waagepetersen, Helle S; Sonnewald, Ursula

    2012-01-01

    The brain is highly susceptible to oxidative injury, and the pentose phosphate pathway (PPP) has been shown to be affected by pathological conditions, such as Alzheimer's disease and traumatic brain injury. While this pathway has been investigated in the intact brain and in astrocytes, little is known about the PPP in neurons. The activity of the PPP was quantified in cultured cerebral cortical and cerebellar neurons after incubation in the presence of [2-13C]glucose or [3-13C]glucose. The activity of the PPP was several fold lower than glycolysis in both types of neurons. While metabolism of 13C-labeled glucose via the PPP does not appear to contribute to the production of releasable lactate, it contributes to labeling of tricarboxylic acid (TCA) cycle intermediates and related amino acids. Based on glutamate isotopomers, it was calculated that PPP activity accounts for ∼6% of glucose metabolism in cortical neurons and ∼4% in cerebellar neurons. This is the first demonstration that pyruvate generated from glucose via the PPP contributes to the synthesis of acetyl CoA for oxidation in the TCA cycle. Moreover, the fact that 13C labeling from glucose is incorporated into glutamate proves that both the oxidative and the nonoxidative stages of the PPP are active in neurons. PMID:22714050

  8. PEPCK Coordinates the Regulation of Central Carbon Metabolism to Promote Cancer Cell Growth.

    PubMed

    Montal, Emily D; Dewi, Ruby; Bhalla, Kavita; Ou, Lihui; Hwang, Bor Jang; Ropell, Ashley E; Gordon, Chris; Liu, Wan-Ju; DeBerardinis, Ralph J; Sudderth, Jessica; Twaddel, William; Boros, Laszlo G; Shroyer, Kenneth R; Duraisamy, Sekhar; Drapkin, Ronny; Powers, R Scott; Rohde, Jason M; Boxer, Matthew B; Wong, Kwok-Kin; Girnun, Geoffrey D

    2015-11-19

    Phosphoenolpyruvate carboxykinase (PEPCK) is well known for its role in gluconeogenesis. However, PEPCK is also a key regulator of TCA cycle flux. The TCA cycle integrates glucose, amino acid, and lipid metabolism depending on cellular needs. In addition, biosynthetic pathways crucial to tumor growth require the TCA cycle for the processing of glucose and glutamine derived carbons. We show here an unexpected role for PEPCK in promoting cancer cell proliferation in vitro and in vivo by increasing glucose and glutamine utilization toward anabolic metabolism. Unexpectedly, PEPCK also increased the synthesis of ribose from non-carbohydrate sources, such as glutamine, a phenomenon not previously described. Finally, we show that the effects of PEPCK on glucose metabolism and cell proliferation are in part mediated via activation of mTORC1. Taken together, these data demonstrate a role for PEPCK that links metabolic flux and anabolic pathways to cancer cell proliferation. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Landscape and flux reveal a new global view and physical quantification of mammalian cell cycle

    PubMed Central

    Li, Chunhe; Wang, Jin

    2014-01-01

    Cell cycles, essential for biological function, have been investigated extensively. However, enabling a global understanding and defining a physical quantification of the stability and function of the cell cycle remains challenging. Based upon a mammalian cell cycle gene network, we uncovered the underlying Mexican hat landscape of the cell cycle. We found the emergence of three local basins of attraction and two major potential barriers along the cell cycle trajectory. The three local basins of attraction characterize the G1, S/G2, and M phases. The barriers characterize the G1 and S/G2 checkpoints, respectively, of the cell cycle, thus providing an explanation of the checkpoint mechanism for the cell cycle from the physical perspective. We found that the progression of a cell cycle is determined by two driving forces: curl flux for acceleration and potential barriers for deceleration along the cycle path. Therefore, the cell cycle can be promoted (suppressed), either by enhancing (suppressing) the flux (representing the energy input) or by lowering (increasing) the barrier along the cell cycle path. We found that both the entropy production rate and energy per cell cycle increase as the growth factor increases. This reflects that cell growth and division are driven by energy or nutrition supply. More energy input increases flux and decreases barrier along the cell cycle path, leading to faster oscillations. We also identified certain key genes and regulations for stability and progression of the cell cycle. Some of these findings were evidenced from experiments whereas others lead to predictions and potential anticancer strategies. PMID:25228772

  10. Astrocytic and neuronal oxidative metabolism are coupled to the rate of glutamate-glutamine cycle in the tree shrew visual cortex.

    PubMed

    Sonnay, Sarah; Poirot, Jordan; Just, Nathalie; Clerc, Anne-Catherine; Gruetter, Rolf; Rainer, Gregor; Duarte, João M N

    2018-03-01

    Astrocytes play an important role in glutamatergic neurotransmission, namely by clearing synaptic glutamate and converting it into glutamine that is transferred back to neurons. The rate of this glutamate-glutamine cycle (V NT ) has been proposed to couple to that of glucose utilization and of neuronal tricarboxylic acid (TCA) cycle. In this study, we tested the hypothesis that glutamatergic neurotransmission is also coupled to the TCA cycle rate in astrocytes. For that we investigated energy metabolism by means of magnetic resonance spectroscopy (MRS) in the primary visual cortex of tree shrews (Tupaia belangeri) under light isoflurane anesthesia at rest and during continuous visual stimulation. After identifying the activated cortical volume by blood oxygenation level-dependent functional magnetic resonance imaging, 1 H MRS was performed to measure stimulation-induced variations in metabolite concentrations. Relative to baseline, stimulation of cortical activity for 20 min caused a reduction of glucose concentration by -0.34 ± 0.09 µmol/g (p < 0.001), as well as a -9% ± 1% decrease of the ratio of phosphocreatine-to-creatine (p < 0.05). Then 13 C MRS during [1,6- 13 C]glucose infusion was employed to measure fluxes of energy metabolism. Stimulation of glutamatergic activity, as indicated by a 20% increase of V NT , resulted in increased TCA cycle rates in neurons by 12% ( VTCAn, p < 0.001) and in astrocytes by 24% ( VTCAg, p = 0.007). We further observed linear relationships between V NT and both VTCAn and VTCAg. Altogether, these results suggest that in the tree shrew primary visual cortex glutamatergic neurotransmission is linked to overall glucose oxidation and to mitochondrial metabolism in both neurons and astrocytes. © 2017 Wiley Periodicals, Inc.

  11. 13C-MFA delineates the photomixotrophic metabolism of Synechocystis sp. PCC 6803 under light- and carbon-sufficient conditions.

    PubMed

    You, Le; Berla, Bert; He, Lian; Pakrasi, Himadri B; Tang, Yinjie J

    2014-05-01

    The central carbon metabolism of cyanobacteria is under debate. For over 50 years, the lack of α-ketoglutarate dehydrogenase has led to the belief that cyanobacteria have an incomplete TCA cycle. Recent in vitro enzymatic experiments suggest that this cycle may in fact be closed. The current study employed (13) C isotopomers to delineate pathways in the cyanobacterium Synechocystis sp. PCC 6803. By tracing the incorporation of supplemented glutamate into the downstream metabolites in the TCA cycle, we observed a direct in vivo transformation of α-ketoglutarate to succinate. Additionally, isotopic tracing of glyoxylate did not show a functional glyoxylate shunt and glyoxylate was used for glycine synthesis. The photomixotrophic carbon metabolism was then profiled with (13) C-MFA under light and carbon-sufficient conditions. We observed that: (i) the in vivo flux through the TCA cycle reactions (α-ketoglutarate → succinate) was minimal (<2%); (ii) the flux ratio of CO2 fixation was six times higher than that of glucose utilization; (iii) the relative flux through the oxidative pentose phosphate pathway was low (<2%); (iv) high flux through malic enzyme served as a main route for pyruvate synthesis. Our results improve the understanding of the versatile metabolism in cyanobacteria and shed light on their application for photo-biorefineries. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Funneled potential and flux landscapes dictate the stabilities of both the states and the flow: Fission yeast cell cycle.

    PubMed

    Luo, Xiaosheng; Xu, Liufang; Han, Bo; Wang, Jin

    2017-09-01

    Using fission yeast cell cycle as an example, we uncovered that the non-equilibrium network dynamics and global properties are determined by two essential features: the potential landscape and the flux landscape. These two landscapes can be quantified through the decomposition of the dynamics into the detailed balance preserving part and detailed balance breaking non-equilibrium part. While the funneled potential landscape is often crucial for the stability of the single attractor networks, we have uncovered that the funneled flux landscape is crucial for the emergence and maintenance of the stable limit cycle oscillation flow. This provides a new interpretation of the origin for the limit cycle oscillations: There are many cycles and loops existed flowing through the state space and forming the flux landscapes, each cycle with a probability flux going through the loop. The limit cycle emerges when a loop stands out and carries significantly more probability flux than other loops. We explore how robustness ratio (RR) as the gap or steepness versus averaged variations or roughness of the landscape, quantifying the degrees of the funneling of the underlying potential and flux landscapes. We state that these two landscapes complement each other with one crucial for stabilities of states on the cycle and the other crucial for the stability of the flow along the cycle. The flux is directly related to the speed of the cell cycle. This allows us to identify the key factors and structure elements of the networks in determining the stability, speed and robustness of the fission yeast cell cycle oscillations. We see that the non-equilibriumness characterized by the degree of detailed balance breaking from the energy pump quantified by the flux is the cause of the energy dissipation for initiating and sustaining the replications essential for the origin and evolution of life. Regulating the cell cycle speed is crucial for designing the prevention and curing strategy of cancer.

  13. Funneled potential and flux landscapes dictate the stabilities of both the states and the flow: Fission yeast cell cycle

    PubMed Central

    2017-01-01

    Using fission yeast cell cycle as an example, we uncovered that the non-equilibrium network dynamics and global properties are determined by two essential features: the potential landscape and the flux landscape. These two landscapes can be quantified through the decomposition of the dynamics into the detailed balance preserving part and detailed balance breaking non-equilibrium part. While the funneled potential landscape is often crucial for the stability of the single attractor networks, we have uncovered that the funneled flux landscape is crucial for the emergence and maintenance of the stable limit cycle oscillation flow. This provides a new interpretation of the origin for the limit cycle oscillations: There are many cycles and loops existed flowing through the state space and forming the flux landscapes, each cycle with a probability flux going through the loop. The limit cycle emerges when a loop stands out and carries significantly more probability flux than other loops. We explore how robustness ratio (RR) as the gap or steepness versus averaged variations or roughness of the landscape, quantifying the degrees of the funneling of the underlying potential and flux landscapes. We state that these two landscapes complement each other with one crucial for stabilities of states on the cycle and the other crucial for the stability of the flow along the cycle. The flux is directly related to the speed of the cell cycle. This allows us to identify the key factors and structure elements of the networks in determining the stability, speed and robustness of the fission yeast cell cycle oscillations. We see that the non-equilibriumness characterized by the degree of detailed balance breaking from the energy pump quantified by the flux is the cause of the energy dissipation for initiating and sustaining the replications essential for the origin and evolution of life. Regulating the cell cycle speed is crucial for designing the prevention and curing strategy of cancer

  14. Transcript abundance on its own cannot be used to infer fluxes in central metabolism

    DOE PAGES

    Schwender, Jorg; Konig, Christina; Klapperstuck, Matthias; ...

    2014-11-28

    An attempt has been made to define the extent to which metabolic flux in central plant metabolism is reflected by changes in the transcriptome and metabolome, based on an analysis of in vitro cultured immature embryos of two oilseed rape (Brassica napus) accessions which contrast for seed lipid accumulation. Metabolic flux analysis (MFA) was used to constrain a flux balance metabolic model which included 671 biochemical and transport reactions within the central metabolism. This highly confident flux information was eventually used for comparative analysis of flux vs. transcript (metabolite). Metabolite profiling succeeded in identifying 79 intermediates within the central metabolism,more » some of which differed quantitatively between the two accessions and displayed a significant shift corresponding to flux. An RNA-Seq based transcriptome analysis revealed a large number of genes which were differentially transcribed in the two accessions, including some enzymes/proteins active in major metabolic pathways. With a few exceptions, differential activity in the major pathways (glycolysis, TCA cycle, amino acid, and fatty acid synthesis) was not reflected in contrasting abundances of the relevant transcripts. The conclusion was that transcript abundance on its own cannot be used to infer metabolic activity/fluxes in central plant metabolism. Lastly, this limitation needs to be borne in mind in evaluating transcriptome data and designing metabolic engineering experiments.« less

  15. Effect of freeze-thaw cycles on greenhouse gas fluxes from peat soils

    NASA Astrophysics Data System (ADS)

    Oh, H. D.; Rezanezhad, F.; Markelov, I.; McCarter, C. P. R.; Van Cappellen, P.

    2017-12-01

    The ongoing displacement of climate zones by global warming is increasing the frequency and intensity of freeze-thaw cycles in middle and high latitude regions, many of which are dominated by organic soils such as peat. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical cycling of carbon and nutrients. In this presentation, we focus on how freeze-thaw cycles influence greenhouse gas fluxes from peat using a newly developed experimental soil column system that simulates realistic soil temperature profiles during freeze-thaw cycles. We measured the surface and subsurface changes to gas and aqueous phase chemistry to delineate the diffusion pathways and quantify soil greenhouse gas fluxes during freeze-thaw cycles using sulfur hexafluoride (SF6) as a conservative tracer. Three peat columns were assembled inside a temperature controlled chamber with different soil structures. All three columns were packed with 40 cm of undisturbed, slightly decomposed peat, where the soil of two columns had an additional 10 cm layer on top (one with loose Sphagnum moss and one with an impermeable plug). The results indicate that the release of SF6 and CO2 gas from the soil surface was influenced by the recurrent development of a physical ice barrier, which prevented gas exchange between the soil and atmosphere during freezing conditions. With the onset of thawing a pulse of SF6 and CO2 occurred, resulting in a flux of 3.24 and 2095.52 µmol/m2h, respectively, due to the build-up of gases in the liquid-phase pore space during freezing. Additionally, we developed a model to determine the specific diffusion coefficients for each peat column. These data allow us to better predict how increased frequency and intensity of freeze-thaw cycles will affect greenhouse gas emissions in northern peat soils.

  16. Cross-talk between branched-chain amino acids and hepatic mitochondria is compromised in nonalcoholic fatty liver disease

    PubMed Central

    Kalavalapalli, Srilaxmi; Bril, Fernando; Garrett, Timothy J.; Nautiyal, Manisha; Mathew, Justin T.; Williams, Caroline M.; Cusi, Kenneth

    2015-01-01

    Elevated plasma branched-chain amino acids (BCAA) in the setting of insulin resistance have been relevant in predicting type 2 diabetes mellitus (T2DM) onset, but their role in the etiology of hepatic insulin resistance remains uncertain. We determined the link between BCAA and dysfunctional hepatic tricarboxylic acid (TCA) cycle, which is a central feature of hepatic insulin resistance and nonalcoholic fatty liver disease (NAFLD). Plasma metabolites under basal fasting and euglycemic hyperinsulinemic clamps (insulin stimulation) were measured in 94 human subjects with varying degrees of insulin sensitivity to identify their relationships with insulin resistance. Furthermore, the impact of elevated BCAA on hepatic TCA cycle was determined in a diet-induced mouse model of NAFLD, utilizing targeted metabolomics and nuclear magnetic resonance (NMR)-based metabolic flux analysis. Insulin stimulation revealed robust relationships between human plasma BCAA and indices of insulin resistance, indicating chronic metabolic overload from BCAA. Human plasma BCAA and long-chain acylcarnitines also showed a positive correlation, suggesting modulation of mitochondrial metabolism by BCAA. Concurrently, mice with NAFLD failed to optimally induce hepatic mTORC1, plasma ketones, and hepatic long-chain acylcarnitines, following acute elevation of plasma BCAA. Furthermore, elevated BCAA failed to induce multiple fluxes through hepatic TCA cycle in mice with NAFLD. Our data suggest that BCAA are essential to mediate efficient channeling of carbon substrates for oxidation through mitochondrial TCA cycle. Impairment of BCAA-mediated upregulation of the TCA cycle could be a significant contributor to mitochondrial dysfunction in NAFLD. PMID:26058864

  17. Alterations in Hepatic Glucose and Energy Metabolism as a Result of Calorie and Carbohydrate Restriction

    PubMed Central

    Browning, Jeffrey D.; Weis, Brian; Davis, Jeannie; Satapati, Santhosh; Merritt, Matthew; Malloy, Craig R.; Burgess, Shawn C.

    2009-01-01

    Carbohydrate-restriction is a common weight-loss approach that modifies hepatic metabolism by increasing gluconeogenesis and ketosis. Because little is known regarding the effect of carbohydrate-restriction on the origin of gluconeogenic precursors (gluconeogenesis from glycerol (GNGglycerol) and lactate/amino acids (GNGPEP)) or its consequence to hepatic energy homeostasis, we studied these parameters in a group of overweight/obese subjects undergoing weight-loss via dietary restriction. We used 2H and 13C tracers and nuclear magnetic resonance spectroscopy to measure the sources of hepatic glucose and TCA cycle flux in weight-stable subjects(n=7) and subjects following carbohydrate-(n=7) or calorie-restriction(n=7). The majority of hepatic glucose production in carbohydrate-restricted subjects came from GNGPEP. The contribution of glycerol to gluconeogenesis was similar in all groups despite evidence of increased fat oxidation in carbohydrate-restricted subjects. A strong correlation between TCA cycle flux and GNGPEP was found, though the reliance on TCA cycle energy production for gluconeogenesis was attenuated in subjects undergoing carbohydrate restriction. Together, these data imply that the TCA cycle is the energetic patron of gluconeogenesis. However, the relationship between these two pathways is modified by carbohydrate restriction, suggesting an increased reliance of the hepatocyte on energy generated outside of the TCA cycle when GNGPEP is maximal. In conclusion, carbohydrate-restriction modifies hepatic gluconeogenesis by increasing reliance on substrates like lactate or amino acids but not glycerol. This modification is associated with a reorganization of hepatic energy metabolism suggestive of enhanced hepatic β-oxidation. PMID:18925642

  18. Application of dynamic metabolomics to examine in vivo skeletal muscle glucose metabolism in the chronically high-fat fed mouse

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kowalski, Greg M., E-mail: greg.kowalski@deakin.edu.au; De Souza, David P.; Burch, Micah L.

    Rationale: Defects in muscle glucose metabolism are linked to type 2 diabetes. Mechanistic studies examining these defects rely on the use of high fat-fed rodent models and typically involve the determination of muscle glucose uptake under insulin-stimulated conditions. While insightful, they do not necessarily reflect the physiology of the postprandial state. In addition, most studies do not examine aspects of glucose metabolism beyond the uptake process. Here we present an approach to study rodent muscle glucose and intermediary metabolism under the dynamic and physiologically relevant setting of the oral glucose tolerance test (OGTT). Methods and results: In vivo muscle glucose andmore » intermediary metabolism was investigated following oral administration of [U-{sup 13}C] glucose. Quadriceps muscles were collected 15 and 60 min after glucose administration and metabolite flux profiling was determined by measuring {sup 13}C mass isotopomers in glycolytic and tricarboxylic acid (TCA) cycle intermediates via gas chromatography–mass spectrometry. While no dietary effects were noted in the glycolytic pathway, muscle from mice fed a high fat diet (HFD) exhibited a reduction in labelling in TCA intermediates. Interestingly, this appeared to be independent of alterations in flux through pyruvate dehydrogenase. In addition, our findings suggest that TCA cycle anaplerosis is negligible in muscle during an OGTT. Conclusions: Under the dynamic physiologically relevant conditions of the OGTT, skeletal muscle from HFD fed mice exhibits alterations in glucose metabolism at the level of the TCA cycle. - Highlights: • Dynamic metabolomics was used to investigate muscle glucose metabolism in vivo. • Mitochondrial TCA cycle metabolism is altered in muscle of HFD mice. • This defect was not pyruvate dehydrogenase mediated, as has been previously thought. • Mitochondrial TCA cycle anaplerosis in muscle is virtually absent during the OGTT.« less

  19. Design of an AdvancedTCA board management controller (IPMC)

    NASA Astrophysics Data System (ADS)

    Mendez, J.; Bobillier, V.; Haas, S.; Joos, M.; Mico, S.; Vasey, F.

    2017-03-01

    The AdvancedTCA (ATCA) standard has been selected as the hardware platform for the upgrade of the back-end electronics of the CMS and ATLAS experiments of the Large Hadron Collider (LHC) . In this context, the electronic systems for experiments group at CERN is running a project to evaluate, specify, design and support xTCA equipment. As part of this project, an Intelligent Platform Management Controller (IPMC) for ATCA blades, based on a commercial solution, has been designed to be used on existing and future ATCA blades. This paper reports on the status of this project presenting the hardware and software developments.

  20. Dynamo generation of magnetic fields in three-dimensional space - Solar cycle main flux tube formation and reversals

    NASA Astrophysics Data System (ADS)

    Yoshimura, H.

    1983-08-01

    The case of the solar magnetic cycle is investigated as a prototype of the dynamo processes involved in the generation of magnetic fields in astrophysics. Magnetohydrodynamic (MHD) equations are solved using a numerical method with a prescribed velocity field in order follow the movement and deformation. It is shown that a simple combination of differential rotation and global convection, given by a linear analysis of fluid dynamics in a rotating sphere, can perpetually create and reverse great magnetic flux tubes encircling the sun. These main flux tubes of the solar cycle are the progenitors of small-scale flux ropes of the solar activity. These findings indicate that magnetic fields can be generated by fluid motions and that MHD equations have a new type of oscillatory solution. It is shown that the solar cycle can be identified with one of these oscillatory solutions. It is proposed that the formation of magnetic flux tubes by streaming plasma flows is a universal mechanism of flux tube formation in astrophysics.

  1. Poly(3-hydroxybutyrate) fuels the tricarboxylic acid cycle and de novo lipid biosynthesis during Bacillus anthracis sporulation.

    PubMed

    Sadykov, Marat R; Ahn, Jong-Sam; Widhelm, Todd J; Eckrich, Valerie M; Endres, Jennifer L; Driks, Adam; Rutkowski, Gregory E; Wingerd, Kevin L; Bayles, Kenneth W

    2017-06-01

    Numerous bacteria accumulate poly(3-hydroxybutyrate) (PHB) as an intracellular reservoir of carbon and energy in response to imbalanced nutritional conditions. In Bacillus spp., where PHB biosynthesis precedes the formation of the dormant cell type called the spore (sporulation), the direct link between PHB accumulation and efficiency of sporulation was observed in multiple studies. Although the idea of PHB as an intracellular carbon and energy source fueling sporulation was proposed several decades ago, the mechanisms underlying PHB contribution to sporulation have not been defined. Here, we demonstrate that PHB deficiency impairs Bacillus anthracis sporulation through diminishing the energy status of the cells and by reducing carbon flux into the tricarboxylic acid (TCA) cycle and de novo lipid biosynthesis. Consequently, this metabolic imbalance decreased biosynthesis of the critical components required for spore integrity and resistance, such as dipicolinic acid (DPA) and the spore's inner membrane. Supplementation of the PHB deficient mutant with exogenous fatty acids overcame these sporulation defects, highlighting the importance of the TCA cycle and lipid biosynthesis during sporulation. Combined, the results of this work reveal the molecular mechanisms of PHB contribution to B. anthracis sporulation and provide valuable insight into the metabolic requirements for this developmental process in Bacillus species. © 2017 John Wiley & Sons Ltd.

  2. Flux Balance Analysis of Cyanobacterial Metabolism: The Metabolic Network of Synechocystis sp. PCC 6803

    PubMed Central

    Knoop, Henning; Gründel, Marianne; Zilliges, Yvonne; Lehmann, Robert; Hoffmann, Sabrina; Lockau, Wolfgang; Steuer, Ralf

    2013-01-01

    Cyanobacteria are versatile unicellular phototrophic microorganisms that are highly abundant in many environments. Owing to their capability to utilize solar energy and atmospheric carbon dioxide for growth, cyanobacteria are increasingly recognized as a prolific resource for the synthesis of valuable chemicals and various biofuels. To fully harness the metabolic capabilities of cyanobacteria necessitates an in-depth understanding of the metabolic interconversions taking place during phototrophic growth, as provided by genome-scale reconstructions of microbial organisms. Here we present an extended reconstruction and analysis of the metabolic network of the unicellular cyanobacterium Synechocystis sp. PCC 6803. Building upon several recent reconstructions of cyanobacterial metabolism, unclear reaction steps are experimentally validated and the functional consequences of unknown or dissenting pathway topologies are discussed. The updated model integrates novel results with respect to the cyanobacterial TCA cycle, an alleged glyoxylate shunt, and the role of photorespiration in cellular growth. Going beyond conventional flux-balance analysis, we extend the computational analysis to diurnal light/dark cycles of cyanobacterial metabolism. PMID:23843751

  3. Nitrous oxide fluxes and nitrogen cycling along a pasturechronosequence in Central Amazonia, Brazil

    Treesearch

    B. Wick; E. Veldkamp; W. Z. de Mello; M. Keller; P. Crill

    2005-01-01

    We studied nitrous oxide (N2O) fluxes and soil nitrogen (N) cycling following forest conversion to pasture in the central Amazon near Santarém, Pará, Brazil. Two undisturbed forest sites and 27 pasture sites of 0.5 to 60 years were sampled once each during wet and dry seasons. In addition to soil-atmosphere fluxes of N...

  4. Alternative reactions at the interface of glycolysis and citric acid cycle in Saccharomyces cerevisiae

    PubMed Central

    van Rossum, Harmen M.; Kozak, Barbara U.; Niemeijer, Matthijs S.; Duine, Hendrik J.; Luttik, Marijke A. H.; Boer, Viktor M.; Kötter, Peter; Daran, Jean-Marc G.; van Maris, Antonius J. A.

    2016-01-01

    Pyruvate and acetyl-coenzyme A, located at the interface between glycolysis and TCA cycle, are important intermediates in yeast metabolism and key precursors for industrially relevant products. Rational engineering of their supply requires knowledge of compensatory reactions that replace predominant pathways when these are inactivated. This study investigates effects of individual and combined mutations that inactivate the mitochondrial pyruvate-dehydrogenase (PDH) complex, extramitochondrial citrate synthase (Cit2) and mitochondrial CoA-transferase (Ach1) in Saccharomyces cerevisiae. Additionally, strains with a constitutively expressed carnitine shuttle were constructed and analyzed. A predominant role of the PDH complex in linking glycolysis and TCA cycle in glucose-grown batch cultures could be functionally replaced by the combined activity of the cytosolic PDH bypass and Cit2. Strongly impaired growth and a high incidence of respiratory deficiency in pda1Δ ach1Δ strains showed that synthesis of intramitochondrial acetyl-CoA as a metabolic precursor requires activity of either the PDH complex or Ach1. Constitutive overexpression of AGP2, HNM1, YAT2, YAT1, CRC1 and CAT2 enabled the carnitine shuttle to efficiently link glycolysis and TCA cycle in l-carnitine-supplemented, glucose-grown batch cultures. Strains in which all known reactions at the glycolysis-TCA cycle interface were inactivated still grew slowly on glucose, indicating additional flexibility at this key metabolic junction. PMID:26895788

  5. Allocating dissipation across a molecular machine cycle to maximize flux

    PubMed Central

    Brown, Aidan I.; Sivak, David A.

    2017-01-01

    Biomolecular machines consume free energy to break symmetry and make directed progress. Nonequilibrium ATP concentrations are the typical free energy source, with one cycle of a molecular machine consuming a certain number of ATP, providing a fixed free energy budget. Since evolution is expected to favor rapid-turnover machines that operate efficiently, we investigate how this free energy budget can be allocated to maximize flux. Unconstrained optimization eliminates intermediate metastable states, indicating that flux is enhanced in molecular machines with fewer states. When maintaining a set number of states, we show that—in contrast to previous findings—the flux-maximizing allocation of dissipation is not even. This result is consistent with the coexistence of both “irreversible” and reversible transitions in molecular machine models that successfully describe experimental data, which suggests that, in evolved machines, different transitions differ significantly in their dissipation. PMID:29073016

  6. The Glyoxylate Cycle in an Arbuscular Mycorrhizal Fungus. Carbon Flux and Gene Expression

    PubMed Central

    Lammers, Peter J.; Jun, Jeongwon; Abubaker, Jehad; Arreola, Raul; Gopalan, Anjali; Bago, Berta; Hernandez-Sebastia, Cinta; Allen, James W.; Douds, David D.; Pfeffer, Philip E.; Shachar-Hill, Yair

    2001-01-01

    The arbuscular mycorrhizal (AM) symbiosis is responsible for huge fluxes of photosynthetically fixed carbon from plants to the soil. Lipid, which is the dominant form of stored carbon in the fungal partner and which fuels spore germination, is made by the fungus within the root and is exported to the extraradical mycelium. We tested the hypothesis that the glyoxylate cycle is central to the flow of carbon in the AM symbiosis. The results of 13C labeling of germinating spores and extraradical mycelium with 13C2-acetate and 13C2-glycerol and analysis by nuclear magnetic resonance spectroscopy indicate that there are very substantial fluxes through the glyoxylate cycle in the fungal partner. Full-length sequences obtained by polymerase chain reaction from a cDNA library from germinating spores of the AM fungus Glomus intraradices showed strong homology to gene sequences for isocitrate lyase and malate synthase from plants and other fungal species. Quantitative real-time polymerase chain reaction measurements show that these genes are expressed at significant levels during the symbiosis. Glyoxysome-like bodies were observed by electron microscopy in fungal structures where the glyoxylate cycle is expected to be active, which is consistent with the presence in both enzyme sequences of motifs associated with glyoxysomal targeting. We also identified among several hundred expressed sequence tags several enzymes of primary metabolism whose expression during spore germination is consistent with previous labeling studies and with fluxes into and out of the glyoxylate cycle. PMID:11706207

  7. Reconstruction and flux analysis of coupling between metabolic pathways of astrocytes and neurons: application to cerebral hypoxia

    PubMed Central

    Çakιr, Tunahan; Alsan, Selma; Saybaşιlι, Hale; Akιn, Ata; Ülgen, Kutlu Ö

    2007-01-01

    Background It is a daunting task to identify all the metabolic pathways of brain energy metabolism and develop a dynamic simulation environment that will cover a time scale ranging from seconds to hours. To simplify this task and make it more practicable, we undertook stoichiometric modeling of brain energy metabolism with the major aim of including the main interacting pathways in and between astrocytes and neurons. Model The constructed model includes central metabolism (glycolysis, pentose phosphate pathway, TCA cycle), lipid metabolism, reactive oxygen species (ROS) detoxification, amino acid metabolism (synthesis and catabolism), the well-known glutamate-glutamine cycle, other coupling reactions between astrocytes and neurons, and neurotransmitter metabolism. This is, to our knowledge, the most comprehensive attempt at stoichiometric modeling of brain metabolism to date in terms of its coverage of a wide range of metabolic pathways. We then attempted to model the basal physiological behaviour and hypoxic behaviour of the brain cells where astrocytes and neurons are tightly coupled. Results The reconstructed stoichiometric reaction model included 217 reactions (184 internal, 33 exchange) and 216 metabolites (183 internal, 33 external) distributed in and between astrocytes and neurons. Flux balance analysis (FBA) techniques were applied to the reconstructed model to elucidate the underlying cellular principles of neuron-astrocyte coupling. Simulation of resting conditions under the constraints of maximization of glutamate/glutamine/GABA cycle fluxes between the two cell types with subsequent minimization of Euclidean norm of fluxes resulted in a flux distribution in accordance with literature-based findings. As a further validation of our model, the effect of oxygen deprivation (hypoxia) on fluxes was simulated using an FBA-derivative approach, known as minimization of metabolic adjustment (MOMA). The results show the power of the constructed model to simulate

  8. The mechanisms of citrate on regulating the distribution of carbon flux in the biosynthesis of uridine 5'-monophosphate by Saccharomyces cerevisiae.

    PubMed

    Chen, Yong; Li, Shuya; Xiong, Jian; Li, Zhenjiang; Bai, Jianxin; Zhang, Lei; Ye, Qi; Ouyang, Pingkai; Ying, Hanjie

    2010-03-01

    A whole cell biocatalytic process for uridine 5'-monophosphate (UMP) production from orotic acid by Saccharomyces cerevisiae was developed. The concentration of UMP was increased by 23% when 1 g l(-1) sodium citrate was fed into the broth. Effects of citrate addition on UMP production were investigated. Glucose-6-phosphate pool was elevated by onefold, while FBP and pyruvate were decreased by 42% and 40%, respectively. Organic acid pools such as acetate and succinate were averagely decreased by 30% and 49%. The results demonstrated that manipulation of citrate levels could be used as a novel tool to regulate the metabolic fluxes distribution among glycolysis, pentose phosphate pathway, and TCA cycle.

  9. A comprehensive analysis of myocardial substrate preference emphasizes the need for a synchronized fluxomic/metabolomic research design.

    PubMed

    Ragavan, Mukundan; Kirpich, Alexander; Fu, Xiaorong; Burgess, Shawn C; McIntyre, Lauren M; Merritt, Matthew E

    2017-06-01

    The heart oxidizes fatty acids, carbohydrates, and ketone bodies inside the tricarboxylic acid (TCA) cycle to generate the reducing equivalents needed for ATP production. Competition between these substrates makes it difficult to estimate the extent of pyruvate oxidation. Previously, hyperpolarized pyruvate detected propionate-mediated activation of carbohydrate oxidation, even in the presence of acetate. In this report, the optimal concentration of propionate for the activation of glucose oxidation was measured in mouse hearts perfused in Langendorff mode. This study was performed with a more physiologically relevant perfusate than the previous work. Increasing concentrations of propionate did not cause adverse effects on myocardial metabolism, as evidenced by unchanged O 2 consumption, TCA cycle flux, and developed pressures. Propionate at 1 mM was sufficient to achieve significant increases in pyruvate dehydrogenase flux (3×), and anaplerosis (6×), as measured by isotopomer analysis. These results further demonstrate the potential of propionate as an aid for the correct estimation of total carbohydrate oxidative capacity in the heart. However, liquid chromotography/mass spectroscopy-based metabolomics detected large changes (~30-fold) in malate and fumarate pool sizes. This observation leads to a key observation regarding mass balance in the TCA cycle; flux through a portion of the cycle can be drastically elevated without changing the O 2 consumption. Copyright © 2017 the American Physiological Society.

  10. Evaluate the seasonal cycle and interannual variability of carbon fluxes and the associated uncertainties using modeled and observed data

    NASA Astrophysics Data System (ADS)

    Zeng, F.; Collatz, G. J.; Ivanoff, A.

    2013-12-01

    We assessed the performance of the Carnegie-Ames-Stanford Approach - Global Fire Emissions Database (CASA-GFED3) terrestrial carbon cycle model in simulating seasonal cycle and interannual variability (IAV) of global and regional carbon fluxes and uncertainties associated with model parameterization. Key model parameters were identified from sensitivity analyses and their uncertainties were propagated through model processes using the Monte Carlo approach to estimate the uncertainties in carbon fluxes and pool sizes. Three independent flux data sets, the global gross primary productivity (GPP) upscaled from eddy covariance flux measurements by Jung et al. (2011), the net ecosystem exchange (NEE) estimated by CarbonTracker, and the eddy covariance flux observations, were used to evaluate modeled fluxes and the uncertainties. Modeled fluxes agree well with both Jung's GPP and CarbonTracker NEE in the amplitude and phase of seasonal cycle, except in the case of GPP in tropical regions where Jung et al. (2011) showed larger fluxes and seasonal amplitude. Modeled GPP IAV is positively correlated (p < 0.1) with Jung's GPP IAV except in the tropics and temperate South America. The correlations between modeled NEE IAV and CarbonTracker NEE IAV are weak at regional to continental scales but stronger when fluxes are aggregated to >40°N latitude. At regional to continental scales flux uncertainties were larger than the IAV in the fluxes for both Jung's GPP and CarbonTracker NEE. Comparisons with eddy covariance flux observations are focused on sites within regions and years of recorded large-scale climate anomalies. We also evaluated modeled biomass using other independent continental biomass estimates and found good agreement. From the comparisons we identify the strengths and weaknesses of the model to capture the seasonal cycle and IAV of carbon fluxes and highlight ways to improve model performance.

  11. Influence of repeated insertion-removal cycles on the force and magnetic flux leakage of magnetic attachments: an in vitro study.

    PubMed

    Hao, Zhichao; Chao, Yonglie; Meng, Yukun; Yin, Hongmin

    2014-08-01

    Magnetic attachments are widely used in overdentures and maxillofacial prostheses. Because the patient will routinely have to insert and remove a removable prosthesis, the retentive force and magnetic flux leakage of the magnetic attachments after repeated insertion and removal must be evaluated to assess their clinical performance. The purpose of this in vitro study was to investigate the retentive force and flux leakage of magnetic attachments after repeated insertion and removal. Magfit EX600W magnet-keeper combinations (n=5) were used in this study. After 5000, 10,000, and 20,000 insertion-removal cycles, the retentive force of the magnetic attachments was measured 5 times at a crosshead speed of 5 mm/min with a universal testing machine. Magnetic flux leakage at 3 positions (P1, the upper surface of the magnet; P2, the lower surface of the keeper; and P3, the lateral side of the magnetic attachment set) was evaluated with a gaussmeter. Data were statistically analyzed by 1-way ANOVA (α=.05). The morphology of the abraded surfaces for both the magnet and the keeper was observed with an optical microscope (5×). The mean retentive force decreased significantly after 5000, 10,000, and 20,000 insertion-removal movements (P<.05). Significant differences of flux leakage were also observed at P1 after 5000 cycles and 10,000 cycles, at P2 after 5000 cycles, and at P3 after 5000, 10,000, and 20,000 insertion-removal cycles (P < .05). However, no significant differences in flux leakage were evident after 20,000 cycles at P1 and 10,000 cycles and 20,000 cycles at P2. Repeated insertion and removal influenced the retentive force and magnetic flux leakage of the magnetic attachments. Retentive force decreased significantly after repeated insertion-removal cycles, whereas the variation of magnetic flux leakage depended on refitting cycles and positions of the magnetic attachments. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by

  12. PEPCK-M expression in mouse liver potentiates, not replaces, PEPCK-C mediated gluconeogenesis

    PubMed Central

    Méndez-Lucas, Andrés; Duarte, João; Sunny, Nishanth E.; Satapati, Santhosh; He, TianTeng; Fu, Xiaorong; Bermúdez, Jordi; Burgess, Shawn C.; Perales, Jose C.

    2013-01-01

    Background & Aims Hepatic gluconeogenesis helps maintain systemic energy homeostasis by compensating for discontinuities in nutrient supply. Liver specific deletion of cytosolic phosphoenolpyruvate carboxykinase (PEPCK-C) abolishes gluconeogenesis from mitochondrial substrates, deregulates lipid metabolism and affects TCA cycle. While, mouse liver almost exclusively expresses PEPCK-C, humans equally present a mitochondrial isozyme (PEPCK-M). Despite clear relevance to human physiology, the role of PEPCK-M and its gluconeogenic potential remain unknown. Here, we test the significance of PEPCK-M in gluconeogenesis and TCA cycle function in liver-specific PEPCK-C knockout and WT mice. Methods The effects of the overexpression of PEPCK-M were examined by a combination of tracer studies and molecular biology techniques. Partial PEPCK-C re-expression was used as a positive control. Metabolic fluxes were evaluated in isolated livers by NMR using 2H and 13C tracers. Gluconeogenic potential, together with metabolic profiling, were investigated in vivo and in primary hepatocytes. Results PEPCK-M expression partially rescued defects in lipid metabolism, gluconeogenesis and TCA cycle function impaired by PEPCK-C deletion, while ~10% re-expression of PEPCK-C normalized most parameters. When PEPCK-M was expressed in the presence of PEPCK-C, the mitochondrial isozyme amplified total gluconeogenic capacity, suggesting autonomous regulation of oxaloacetate to phosphoenolpyruvate fluxes by the individual isoforms. Conclusions We conclude that PEPCK-M has gluconeogenic potential per se, and cooperates with PEPCK-C to adjust gluconeogenic/TCA flux to changes in substrate or energy availability, hinting at a role in the regulation of glucose and lipid metabolism in human liver. PMID:23466304

  13. Elucidating the role of copper in CHO cell energy metabolism using (13)C metabolic flux analysis.

    PubMed

    Nargund, Shilpa; Qiu, Jinshu; Goudar, Chetan T

    2015-01-01

    (13)C-metabolic flux analysis was used to understand copper deficiency-related restructuring of energy metabolism, which leads to excessive lactate production in recombinant protein-producing CHO cells. Stationary-phase labeling experiments with U-(13)C glucose were conducted on CHO cells grown under high and limiting copper in 3 L fed-batch bioreactors. The resultant labeling patterns of soluble metabolites were measured by GC-MS and used to estimate metabolic fluxes in the central carbon metabolism pathways using OpenFlux. Fluxes were evaluated 300 times from stoichiometrically feasible random guess values and their confidence intervals calculated by Monte Carlo simulations. Results from metabolic flux analysis exhibited significant carbon redistribution throughout the metabolic network in cells under Cu deficiency. Specifically, glycolytic fluxes increased (25%-79% relative to glucose uptake) whereas fluxes through the TCA and pentose phosphate pathway (PPP) were lower (15%-23% and 74%, respectively) compared with the Cu-containing condition. Furthermore, under Cu deficiency, 33% of the flux entering TCA via the pyruvate node was redirected to lactate and malate production. Based on these results, we hypothesize that Cu deficiency disrupts the electron transport chain causing ATP deficiency, redox imbalance, and oxidative stress, which in turn drive copper-deficient CHO cells to produce energy via aerobic glycolysis, which is associated with excessive lactate production, rather than the more efficient route of oxidative phosphorylation. © 2015 American Institute of Chemical Engineers.

  14. The Aurora kinase A inhibitor TC-A2317 disrupts mitotic progression and inhibits cancer cell proliferation

    PubMed Central

    Min, Yoo Hong; Kim, Wootae; Kim, Ja-Eun

    2016-01-01

    Mitotic progression is crucial for the maintenance of chromosomal stability. A proper progression is ensured by the activities of multiple kinases. One of these enzymes, the serine/threonine kinase Aurora A, is required for proper mitosis through the regulation of centrosome and spindle assembly. In this study, we functionally characterized a newly developed Aurora kinase A inhibitor, TC-A2317. In human lung cancer cells, TC-A2317 slowed proliferation by causing aberrant formation of centrosome and microtubule spindles and prolonging the duration of mitosis. Abnormal mitotic progression led to accumulation of cells containing micronuclei or multinuclei. Furthermore, TC-A2317–treated cells underwent apoptosis, autophagy or senescence depending on cell type. In addition, TC-A2317 inactivated the spindle assembly checkpoint triggered by paclitaxel, thereby exacerbating mitotic catastrophe. Consistent with this, the expression level of Aurora A in tumors was inversely correlated with survival in lung cancer patients. Collectively, these data suggest that inhibition of Aurora kinase A using TC-A2317 is a promising target for anti-cancer therapeutics. PMID:27713168

  15. Dynamic flux balancing elucidates NAD(P)H production as limiting response to furfural inhibition in Saccharomyces cerevisiae.

    PubMed

    Pornkamol, Unrean; Franzen, Carl J

    2015-08-01

    Achieving efficient and economical lignocellulose-based bioprocess requires a robust organism tolerant to furfural, a major inhibitory compound present in lignocellulosic hydrolysate. The aim of this study was to develop a model that could generate quantitative descriptions of cell metabolism for elucidating the cell's adaptive response to furfural. Such a modelling tool could provide strategies for the design of more robust cells. A dynamic flux balance (dFBA) model of Saccharomyces cerevisiae was created by coupling a kinetic fermentation model with a previously published genome-scale stoichiometric model. The dFBA model was used for studying intracellular and extracellular flux responses to furfural perturbations under steady state and dynamic conditions. The predicted effects of furfural on dynamic flux profiles agreed well with previously published experimental results. The model showed that the yeast cell adjusts its metabolism in response to furfural challenge by increasing fluxes through the pentose phosphate pathway, TCA cycle, and proline and serine biosynthesis in order to meet the high demand of NAD(P)H cofactors. The model described here can be used to aid in systematic optimization of the yeast, as well as of the fermentation process, for efficient lignocellulosic ethanol production. Copyright © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. A meta-analysis of soil salinization effects on nitrogen pools, cycles and fluxes in coastal ecosystems.

    PubMed

    Zhou, Minghua; Butterbach-Bahl, Klaus; Vereecken, Harry; Brüggemann, Nicolas

    2017-03-01

    Salinity intrusion caused by land subsidence resulting from increasing groundwater abstraction, decreasing river sediment loads and increasing sea level because of climate change has caused widespread soil salinization in coastal ecosystems. Soil salinization may greatly alter nitrogen (N) cycling in coastal ecosystems. However, a comprehensive understanding of the effects of soil salinization on ecosystem N pools, cycling processes and fluxes is not available for coastal ecosystems. Therefore, we compiled data from 551 observations from 21 peer-reviewed papers and conducted a meta-analysis of experimental soil salinization effects on 19 variables related to N pools, cycling processes and fluxes in coastal ecosystems. Our results showed that the effects of soil salinization varied across different ecosystem types and salinity levels. Soil salinization increased plant N content (18%), soil NH 4 + (12%) and soil total N (210%), although it decreased soil NO 3 - (2%) and soil microbial biomass N (74%). Increasing soil salinity stimulated soil N 2 O fluxes as well as hydrological NH 4 + and NO 2 - fluxes more than threefold, although it decreased the hydrological dissolved organic nitrogen (DON) flux (59%). Soil salinization also increased the net N mineralization by 70%, although salinization effects were not observed on the net nitrification, denitrification and dissimilatory nitrate reduction to ammonium in this meta-analysis. Overall, this meta-analysis improves our understanding of the responses of ecosystem N cycling to soil salinization, identifies knowledge gaps and highlights the urgent need for studies on the effects of soil salinization on coastal agro-ecosystem and microbial N immobilization. Additional increases in knowledge are critical for designing sustainable adaptation measures to the predicted intrusion of salinity intrusion so that the productivity of coastal agro-ecosystems can be maintained or improved and the N losses and pollution of the natural

  17. Oxaloacetate Ameliorates Chemical Liver Injury via Oxidative Stress Reduction and Enhancement of Bioenergetic Fluxes.

    PubMed

    Kuang, Ye; Han, Xiaoyun; Xu, Mu; Wang, Yue; Zhao, Yuxiang; Yang, Qing

    2018-05-31

    Chemical injury is partly due to free radical lipid peroxidation, which can induce oxidative stress and produce a large number of reactive oxygen species (ROS). Oxaloacetic acid is an important intermediary in the tricarboxylic acid cycle (TCA cycle) and participates in metabolism and energy production. In our study, we found that oxaloacetate (OA) effectively alleviated liver injury which was induced by hydrogen peroxide (H₂O₂) in vitro and carbon tetrachloride (CCl₄) in vivo. OA scavenged ROS, prevented oxidative damage and maintained the normal structure of mitochondria. We further confirmed that OA increased adenosine triphosphate (ATP) by promoting the TCA production cycle and oxidative phosphorylation (OXPHOS). Finally, OA inhibited the mitogen-activated protein kinase (MAPK) and apoptotic pathways by suppressing tumor necrosis factor-α (TNF-α). Our findings reveal a mechanism for OA ameliorating chemical liver injury and suggest a possible implementation for preventing the chemical liver injury.

  18. IRIS Toxicological Review of Trichloroacetic Acid (TCA) ...

    EPA Pesticide Factsheets

    EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Trichloroacetic acid (TCA) that when finalized will appear on the Integrated Risk Information System (IRIS) database. The draft Toxicological Review of trichloroacetic acid provides scientific support and rationale for the hazard and dose-response assessment pertaining to chronic exposure to trichloroacetic acid.

  19. Glycation inhibits trichloroacetic acid (TCA)-induced whey protein precipitation

    USDA-ARS?s Scientific Manuscript database

    Four different WPI saccharide conjugates were successfully prepared to test whether glycation could inhibit WPI precipitation induced by trichloroacetic acid (TCA). Conjugates molecular weights after glycation were analyzed with SDS-PAGE. No significant secondary structure change due to glycation wa...

  20. NASA's Carbon Monitoring System Flux-Pilot Project: A Multi-Component Analysis System for Carbon-Cycle Research and Monitoring

    NASA Technical Reports Server (NTRS)

    Pawson, S.; Gunson, M.; Potter, C.; Jucks, K.

    2012-01-01

    The importance of greenhouse gas increases for climate motivates NASA s observing strategy for CO2 from space, including the forthcoming Orbiting Carbon Observatory (OCO-2) mission. Carbon cycle monitoring, including attribution of atmospheric concentrations to regional emissions and uptake, requires a robust modeling and analysis infrastructure to optimally extract information from the observations. NASA's Carbon-Monitoring System Flux-Pilot Project (FPP) is a prototype for such analysis, combining a set of unique tools to facilitate analysis of atmospheric CO2 along with fluxes between the atmosphere and the terrestrial biosphere or ocean. NASA's analysis system is unique, in that it combines information and expertise from the land, oceanic, and atmospheric branches of the carbon cycle and includes some estimates of uncertainty. Numerous existing space-based missions provide information of relevance to the carbon cycle. This study describes the components of the FPP framework, assessing the realism of computed fluxes, thus providing the basis for research and monitoring applications. Fluxes are computed using data-constrained terrestrial biosphere models and physical ocean models, driven by atmospheric observations and assimilating ocean-color information. Use of two estimates provides a measure of uncertainty in the fluxes. Along with inventories of other emissions, these data-derived fluxes are used in transport models to assess their consistency with atmospheric CO2 observations. Closure is achieved by using a four-dimensional data assimilation (inverse) approach that adjusts the terrestrial biosphere fluxes to make them consistent with the atmospheric CO2 observations. Results will be shown, illustrating the year-to-year variations in land biospheric and oceanic fluxes computed in the FPP. The signals of these surface-flux variations on atmospheric CO2 will be isolated using forward modeling tools, which also incorporate estimates of transport error. The

  1. Biochemical consequences of alginate encapsulation: a NMR study of insulin-secreting cells.

    PubMed

    Simpson, Nicholas E; Grant, Samuel C; Gustavsson, Lenita; Peltonen, Vilje-Mia; Blackband, Stephen J; Constantinidis, Ioannis

    2006-04-01

    In this study we explore the biochemical consequences of alginate encapsulation on betaTC3 cells. (13)C NMR spectroscopy and isotopomer analysis were used to investigate the effects of encapsulation on several enzymatic processes associated with the TCA cycle. Our data show statistically significant differences in various enzymatic fluxes related to the TCA cycle and insulin secretion between monolayer and alginate-encapsulated cultures. The principal cause for these effects was the process of trypsinization. Embedding the trypsinized cells in alginate beads did not have a compounded effect on the enzymatic fluxes of entrapped cells. However, an additional small but statistically significant decrease in insulin secretion was measured in encapsulated cells. Finally, differences in either enzymatic fluxes or glucose consumption as a function of bead diameter were not observed. However, differences in T(2), assessed by (1)H NMR microimaging, were observed as a function of bead diameter, suggesting that smaller beads became more organized with time in culture, while larger beads displayed a looser organization.

  2. The Yeast Cyclin-Dependent Kinase Routes Carbon Fluxes to Fuel Cell Cycle Progression.

    PubMed

    Ewald, Jennifer C; Kuehne, Andreas; Zamboni, Nicola; Skotheim, Jan M

    2016-05-19

    Cell division entails a sequence of processes whose specific demands for biosynthetic precursors and energy place dynamic requirements on metabolism. However, little is known about how metabolic fluxes are coordinated with the cell division cycle. Here, we examine budding yeast to show that more than half of all measured metabolites change significantly through the cell division cycle. Cell cycle-dependent changes in central carbon metabolism are controlled by the cyclin-dependent kinase (Cdk1), a major cell cycle regulator, and the metabolic regulator protein kinase A. At the G1/S transition, Cdk1 phosphorylates and activates the enzyme Nth1, which funnels the storage carbohydrate trehalose into central carbon metabolism. Trehalose utilization fuels anabolic processes required to reliably complete cell division. Thus, the cell cycle entrains carbon metabolism to fuel biosynthesis. Because the oscillation of Cdk activity is a conserved feature of the eukaryotic cell cycle, we anticipate its frequent use in dynamically regulating metabolism for efficient proliferation. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. The avian cell line AGE1.CR.pIX characterized by metabolic flux analysis

    PubMed Central

    2014-01-01

    Background In human vaccine manufacturing some pathogens such as Modified Vaccinia Virus Ankara, measles, mumps virus as well as influenza viruses are still produced on primary material derived from embryonated chicken eggs. Processes depending on primary cell culture, however, are difficult to adapt to modern vaccine production. Therefore, we derived previously a continuous suspension cell line, AGE1.CR.pIX, from muscovy duck and established chemically-defined media for virus propagation. Results To better understand vaccine production processes, we developed a stoichiometric model of the central metabolism of AGE1.CR.pIX cells and applied flux variability and metabolic flux analysis. Results were compared to literature dealing with mammalian and insect cell culture metabolism focusing on the question whether cultured avian cells differ in metabolism. Qualitatively, the observed flux distribution of this avian cell line was similar to distributions found for mammalian cell lines (e.g. CHO, MDCK cells). In particular, glucose was catabolized inefficiently and glycolysis and TCA cycle seem to be only weakly connected. Conclusions A distinguishing feature of the avian cell line is that glutaminolysis plays only a minor role in energy generation and production of precursors, resulting in low extracellular ammonia concentrations. This metabolic flux study is the first for a continuous avian cell line. It provides a basis for further metabolic analyses to exploit the biotechnological potential of avian and vertebrate cell lines and to develop specific optimized cell culture processes, e.g. vaccine production processes. PMID:25077436

  4. The avian cell line AGE1.CR.pIX characterized by metabolic flux analysis.

    PubMed

    Lohr, Verena; Hädicke, Oliver; Genzel, Yvonne; Jordan, Ingo; Büntemeyer, Heino; Klamt, Steffen; Reichl, Udo

    2014-07-30

    In human vaccine manufacturing some pathogens such as Modified Vaccinia Virus Ankara, measles, mumps virus as well as influenza viruses are still produced on primary material derived from embryonated chicken eggs. Processes depending on primary cell culture, however, are difficult to adapt to modern vaccine production. Therefore, we derived previously a continuous suspension cell line, AGE1.CR.pIX, from muscovy duck and established chemically-defined media for virus propagation. To better understand vaccine production processes, we developed a stoichiometric model of the central metabolism of AGE1.CR.pIX cells and applied flux variability and metabolic flux analysis. Results were compared to literature dealing with mammalian and insect cell culture metabolism focusing on the question whether cultured avian cells differ in metabolism. Qualitatively, the observed flux distribution of this avian cell line was similar to distributions found for mammalian cell lines (e.g. CHO, MDCK cells). In particular, glucose was catabolized inefficiently and glycolysis and TCA cycle seem to be only weakly connected. A distinguishing feature of the avian cell line is that glutaminolysis plays only a minor role in energy generation and production of precursors, resulting in low extracellular ammonia concentrations. This metabolic flux study is the first for a continuous avian cell line. It provides a basis for further metabolic analyses to exploit the biotechnological potential of avian and vertebrate cell lines and to develop specific optimized cell culture processes, e.g. vaccine production processes.

  5. IRIS Toxicological Review of Trichloroacetic Acid (TCA) (External Review Draft)

    EPA Science Inventory

    EPA is conducting a peer review and public comment of the scientific basis supporting the human health hazard and dose-response assessment of Trichloroacetic acid (TCA) that when finalized will appear on the Integrated Risk Information System (IRIS) database.

  6. In vivo 13C MRS in the mouse brain at 14.1 Tesla and metabolic flux quantification under infusion of [1,6-13C2]glucose.

    PubMed

    Lai, Marta; Lanz, Bernard; Poitry-Yamate, Carole; Romero, Jackeline F; Berset, Corina M; Cudalbu, Cristina; Gruetter, Rolf

    2017-01-01

    In vivo 13 C magnetic resonance spectroscopy (MRS) enables the investigation of cerebral metabolic compartmentation while, e.g. infusing 13 C-labeled glucose. Metabolic flux analysis of 13 C turnover previously yielded quantitative information of glutamate and glutamine metabolism in humans and rats, while the application to in vivo mouse brain remains exceedingly challenging. In the present study, 13 C direct detection at 14.1 T provided highly resolved in vivo spectra of the mouse brain while infusing [1,6- 13 C 2 ]glucose for up to 5 h. 13 C incorporation to glutamate and glutamine C4, C3, and C2 and aspartate C3 were detected dynamically and fitted to a two-compartment model: flux estimation of neuron-glial metabolism included tricarboxylic acid cycle (TCA) flux in astrocytes (V g  = 0.16 ± 0.03 µmol/g/min) and neurons (V TCA n  = 0.56 ± 0.03 µmol/g/min), pyruvate carboxylase activity (V PC  = 0.041 ± 0.003 µmol/g/min) and neurotransmission rate (V NT  = 0.084 ± 0.008 µmol/g/min), resulting in a cerebral metabolic rate of glucose (CMR glc ) of 0.38 ± 0.02 µmol/g/min, in excellent agreement with that determined with concomitant 18 F-fluorodeoxyglucose positron emission tomography ( 18 FDG PET).We conclude that modeling of neuron-glial metabolism in vivo is accessible in the mouse brain from 13 C direct detection with an unprecedented spatial resolution under [1,6- 13 C 2 ]glucose infusion.

  7. Tricarboxylic acid cycle inhibition by Li+ in the human neuroblastoma SH-SY5Y cell line: a 13C NMR isotopomer analysis.

    PubMed

    Fonseca, Carla P; Jones, John G; Carvalho, Rui A; Jeffrey, F Mark H; Montezinho, Liliana P; Geraldes, Carlos F G C; Castro, M M C A

    2005-11-01

    Li+ effects on glucose metabolism and on the competitive metabolism of glucose and lactate were investigated in the human neuroblastoma SH-SY5Y cell line using 13C NMR spectroscopy. The metabolic model proposed for glucose and lactate metabolism in these cells, based on tcaCALC best fitting solutions, for both control and Li+ conditions, was consistent with: (i) a single pyruvate pool; (ii) anaplerotic flux from endogenous unlabelled substrates; (iii) no cycling between pyruvate and oxaloacetate. Li+ was shown to induce a 38 and 53% decrease, for 1 and 15 mM Li+, respectively, in the rate of glucose conversion into pyruvate, when [U-13C]glucose was present, while no effects on lactate production were observed. Pyruvate oxidation by the tricarboxylic acid cycle and citrate synthase flux were shown to be significantly reduced by 64 and 84% in the presence of 1 and 15 mM Li+, respectively, suggesting a direct inhibitory effect of Li+ on tricarboxylic acid cycle flux. This work also showed that when both glucose and lactate are present as energetic substrates, SH-SY5Y cells preferentially consumed exogenous lactate over glucose, as 62% of the acetyl-CoA was derived from [3-13C]lactate while only 26% was derived from [U-13C]glucose. Li+ did not significantly affect the relative utilisation of these two substrates by the cells or the residual contribution of unlabelled endogenous sources for the acetyl-CoA pool.

  8. IRIS Toxicological Review of Trichloroacetic Acid (TCA) ...

    EPA Pesticide Factsheets

    EPA is releasing the draft report, Toxicological Review of Trichloroacetic Acid (TCA), that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment Development Process. Comments received from other Federal agencies and White House Offices are provided below with external peer review panel comments. The draft Toxicological Review of Trichloroacetic Acid provides scientific support and rationale for the hazard identification and dose-response assessment pertaining to chronic exposure to trichloroacetic acid.

  9. Comparative study of 15% TCA peel versus 35% glycolic acid peel for the treatment of melasma

    PubMed Central

    Puri, Neerja

    2012-01-01

    Background: Chemical peels are the mainstay of a cosmetic practitioner's armamentarium because they can be used to treat some skin disorders and can provide aesthetic benefit. Objectives: To compare 15% TCA peel and 35% glycolic acid peel for the treatment of melasma. Material and Methods: We selected 30 participants of melasma aged between 20 and 50 years from the dermatology outpatient department and treated equal numbers with 15% TCA and 35% glycolic acid. Results: Subjective response as graded by the patient showed good or very good response in 70% participants in the glycolic acid group and 64% in the TCA group. Conclusions: There was statistically insignificant difference in the efficacy between the two groups for the treatment of melasma. PMID:23130283

  10. Modelling urea-cycle disorder citrullinemia type 1 with disease-specific iPSCs.

    PubMed

    Yoshitoshi-Uebayashi, Elena Yukie; Toyoda, Taro; Yasuda, Katsutaro; Kotaka, Maki; Nomoto, Keiko; Okita, Keisuke; Yasuchika, Kentaro; Okamoto, Shinya; Takubo, Noriyuki; Nishikubo, Toshiya; Soga, Tomoyoshi; Uemoto, Shinji; Osafune, Kenji

    2017-05-06

    Citrullinemia type 1 (CTLN1) is a urea cycle disorder (UCD) caused by mutations of the ASS1 gene, which is responsible for production of the enzyme argininosuccinate synthetase (ASS), and classically presented as life-threatening hyperammonemia in newborns. Therapeutic options are limited, and neurological sequelae may persist. To understand the pathophysiology and find novel treatments, induced pluripotent stem cells (iPSCs) were generated from a CTLN1 patient and differentiated into hepatocyte-like cells (HLCs). CTLN1-HLCs have lower ureagenesis, recapitulating part of the patient's phenotype. l-arginine, an amino acid clinically used for UCD treatment, improved this phenotype in vitro. Metabolome analysis revealed an increase in tricarboxylic acid (TCA) cycle metabolites in CTLN1, suggesting a connection between CTLN1 and the TCA cycle. This CTLN1-iPSC model improves the understanding of CTLN1 pathophysiology and can be used to pursue new therapeutic approaches. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Lipogenesis and Redox Balance in Nitrogen-Fixing Pea Bacteroids.

    PubMed

    Terpolilli, Jason J; Masakapalli, Shyam K; Karunakaran, Ramakrishnan; Webb, Isabel U C; Green, Rob; Watmough, Nicholas J; Kruger, Nicholas J; Ratcliffe, R George; Poole, Philip S

    2016-10-15

    Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the tricarboxylic acid (TCA) cycle to generate NAD(P)H for reduction of N2 Metabolic flux analysis of laboratory-grown Rhizobium leguminosarum showed that the flux from [(13)C]succinate was consistent with respiration of an obligate aerobe growing on a TCA cycle intermediate as the sole carbon source. However, the instability of fragile pea bacteroids prevented their steady-state labeling under N2-fixing conditions. Therefore, comparative metabolomic profiling was used to compare free-living R. leguminosarum with pea bacteroids. While the TCA cycle was shown to be essential for maximal rates of N2 fixation, levels of pyruvate (5.5-fold reduced), acetyl coenzyme A (acetyl-CoA; 50-fold reduced), free coenzyme A (33-fold reduced), and citrate (4.5-fold reduced) were much lower in bacteroids. Instead of completely oxidizing acetyl-CoA, pea bacteroids channel it into both lipid and the lipid-like polymer poly-β-hydroxybutyrate (PHB), the latter via a type III PHB synthase that is active only in bacteroids. Lipogenesis may be a fundamental requirement of the redox poise of electron donation to N2 in all legume nodules. Direct reduction by NAD(P)H of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent with their redox potentials. Instead, bacteroids must balance the production of NAD(P)H from oxidation of acetyl-CoA in the TCA cycle with its storage in PHB and lipids. Biological nitrogen fixation by symbiotic bacteria (rhizobia) in legume root nodules is an energy-expensive process. Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the TCA cycle to generate NAD(P)H for reduction of N2 However, direct reduction of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent with their redox

  12. Lipogenesis and Redox Balance in Nitrogen-Fixing Pea Bacteroids

    PubMed Central

    Terpolilli, Jason J.; Masakapalli, Shyam K.; Karunakaran, Ramakrishnan; Webb, Isabel U. C.; Green, Rob; Watmough, Nicholas J.; Kruger, Nicholas J.; Ratcliffe, R. George

    2016-01-01

    ABSTRACT Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the tricarboxylic acid (TCA) cycle to generate NAD(P)H for reduction of N2. Metabolic flux analysis of laboratory-grown Rhizobium leguminosarum showed that the flux from [13C]succinate was consistent with respiration of an obligate aerobe growing on a TCA cycle intermediate as the sole carbon source. However, the instability of fragile pea bacteroids prevented their steady-state labeling under N2-fixing conditions. Therefore, comparative metabolomic profiling was used to compare free-living R. leguminosarum with pea bacteroids. While the TCA cycle was shown to be essential for maximal rates of N2 fixation, levels of pyruvate (5.5-fold reduced), acetyl coenzyme A (acetyl-CoA; 50-fold reduced), free coenzyme A (33-fold reduced), and citrate (4.5-fold reduced) were much lower in bacteroids. Instead of completely oxidizing acetyl-CoA, pea bacteroids channel it into both lipid and the lipid-like polymer poly-β-hydroxybutyrate (PHB), the latter via a type III PHB synthase that is active only in bacteroids. Lipogenesis may be a fundamental requirement of the redox poise of electron donation to N2 in all legume nodules. Direct reduction by NAD(P)H of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent with their redox potentials. Instead, bacteroids must balance the production of NAD(P)H from oxidation of acetyl-CoA in the TCA cycle with its storage in PHB and lipids. IMPORTANCE Biological nitrogen fixation by symbiotic bacteria (rhizobia) in legume root nodules is an energy-expensive process. Within legume root nodules, rhizobia differentiate into bacteroids that oxidize host-derived dicarboxylic acids, which is assumed to occur via the TCA cycle to generate NAD(P)H for reduction of N2. However, direct reduction of the likely electron donors for nitrogenase, such as ferredoxin, is inconsistent

  13. Ca cycling and isotopic fluxes in forested ecosystems in Hawaii

    USGS Publications Warehouse

    Wiegand, B.A.; Chadwick, O.A.; Vitousek, P.M.; Wooden, J.L.

    2005-01-01

    Biogeochemical processes fractionate Ca isotopes in plants and soils along a 4 million year developmental sequence in the Hawaiian Islands. We observed that plants preferentially take up 40Ca relative to 44Ca, and that biological fractionation and changes in the relative contributions from volcanic and marine sources produce a significant increase in 44Ca in soil exchangeable pools. Our results imply moderate fluxes enriched in 44Ca from strongly nutrient-depleted old soils, in contrast with high 40Ca fluxes in young and little weathered environments. In addition, biological fractionation controls divergent geochemical pathways of Ca and Sr in the plant-soil system. While Ca depletes progressively with increasing soil age, Sr/Ca ratios increase systematically. Sr isotope ratios provide a valuable tracer for provenance studies of alkaline earth elements in forested ecosystems, but its usefulness is limited when deciphering biogeochemical processes involved in the terrestrial Ca cycle. Ca isotopes in combination with Sr/ Ca ratios reveal more complex processes involved in the biogeochemistry of Ca and Sr. Copyright 2005 by the American Geophysical Union.

  14. Use of response surface methodology in a fed-batch process for optimization of tricarboxylic acid cycle intermediates to achieve high levels of canthaxanthin from Dietzia natronolimnaea HS-1.

    PubMed

    Nasri Nasrabadi, Mohammad Reza; Razavi, Seyed Hadi

    2010-04-01

    In this work, we applied statistical experimental design to a fed-batch process for optimization of tricarboxylic acid cycle (TCA) intermediates in order to achieve high-level production of canthaxanthin from Dietzia natronolimnaea HS-1 cultured in beet molasses. A fractional factorial design (screening test) was first conducted on five TCA cycle intermediates. Out of the five TCA cycle intermediates investigated via screening tests, alfaketoglutarate, oxaloacetate and succinate were selected based on their statistically significant (P<0.05) and positive effects on canthaxanthin production. These significant factors were optimized by means of response surface methodology (RSM) in order to achieve high-level production of canthaxanthin. The experimental results of the RSM were fitted with a second-order polynomial equation by means of a multiple regression technique to identify the relationship between canthaxanthin production and the three TCA cycle intermediates. By means of this statistical design under a fed-batch process, the optimum conditions required to achieve the highest level of canthaxanthin (13172 + or - 25 microg l(-1)) were determined as follows: alfaketoglutarate, 9.69 mM; oxaloacetate, 8.68 mM; succinate, 8.51 mM. Copyright 2009 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  15. Performance improvement of GaN-based metal-semiconductor-metal photodiodes grown on Si(111) substrate by thermal cycle annealing process

    NASA Astrophysics Data System (ADS)

    Lin, Jyun-Hao; Huang, Shyh-Jer; Su, Yan-Kuin

    2014-01-01

    A simple thermal cycle annealing (TCA) process was used to improve the quality of GaN grown on a Si substrate. The X-ray diffraction (XRD) and etch pit density (EPD) results revealed that using more process cycles, the defect density cannot be further reduced. However, the performance of GaN-based metal-semiconductor-metal (MSM) photodiodes (PDs) prepared on Si substrates showed significant improvement. With a two-cycle TCA process, it is found that the dark current of the device was only 1.46 × 10-11 A, and the photo-to-dark-current contrast ratio was about 1.33 × 105 at 5 V. Also, the UV/visible rejection ratios can reach as high as 1077.

  16. Easy regulation of metabolic flux in Escherichia coli using an endogenous type I-E CRISPR-Cas system.

    PubMed

    Chang, Yizhao; Su, Tianyuan; Qi, Qingsheng; Liang, Quanfeng

    2016-11-15

    Clustered regularly interspaced short palindromic repeats interference (CRISPRi) is a recently developed powerful tool for gene regulation. In Escherichia coli, the type I CRISPR system expressed endogenously shall be easy for internal regulation without causing metabolic burden in compared with the widely used type II system, which expressed dCas9 as an additional plasmid. By knocking out cas3 and activating the expression of CRISPR-associated complex for antiviral defense (Cascade), we constructed a native CRISPRi system in E. coli. Downregulation of the target gene from 6 to 82% was demonstrated using green fluorescent protein. Regulation of the citrate synthase gene (gltA) in the TCA cycle affected host metabolism. The effect of metabolic flux regulation was demonstrated by the poly-3-hydroxbutyrate (PHB) accumulation in vivo. By regulating native gltA in E. coli using an engineered endogenous type I-E CRISPR system, we redirected metabolic flux from the central metabolic pathway to the PHB synthesis pathway. This study demonstrated that the endogenous type I-E CRISPR-Cas system is an easy and effective method for regulating internal metabolic pathways, which is useful for product synthesis.

  17. Worldlines and worldsheets for non-abelian lattice field theories: Abelian color fluxes and Abelian color cycles

    NASA Astrophysics Data System (ADS)

    Gattringer, Christof; Göschl, Daniel; Marchis, Carlotta

    2018-03-01

    We discuss recent developments for exact reformulations of lattice field theories in terms of worldlines and worldsheets. In particular we focus on a strategy which is applicable also to non-abelian theories: traces and matrix/vector products are written as explicit sums over color indices and a dual variable is introduced for each individual term. These dual variables correspond to fluxes in both, space-time and color for matter fields (Abelian color fluxes), or to fluxes in color space around space-time plaquettes for gauge fields (Abelian color cycles). Subsequently all original degrees of freedom, i.e., matter fields and gauge links, can be integrated out. Integrating over complex phases of matter fields gives rise to constraints that enforce conservation of matter flux on all sites. Integrating out phases of gauge fields enforces vanishing combined flux of matter-and gauge degrees of freedom. The constraints give rise to a system of worldlines and worldsheets. Integrating over the factors that are not phases (e.g., radial degrees of freedom or contributions from the Haar measure) generates additional weight factors that together with the constraints implement the full symmetry of the conventional formulation, now in the language of worldlines and worldsheets. We discuss the Abelian color flux and Abelian color cycle strategies for three examples: the SU(2) principal chiral model with chemical potential coupled to two of the Noether charges, SU(2) lattice gauge theory coupled to staggered fermions, as well as full lattice QCD with staggered fermions. For the principal chiral model we present some simulation results that illustrate properties of the worldline dynamics at finite chemical potentials.

  18. Molecular structure and spectral properties of ethyl 3-quinolinecarboxylate (E3Q) and [Ag(E3Q)2(TCA)] complex (TCA = Trichloroacetate)

    NASA Astrophysics Data System (ADS)

    Soliman, Saied M.; Kassem, Taher S.; Badr, Ahmed M. A.; Abou Youssef, Morsy A.; Assem, Rania

    2014-09-01

    A new [Ag(E3Q)2(TCA)] complex; (E3Q = Ethyl 3-quinolinecarboxylate and TCA = Trichloroacetate) has been synthesized and characterized using elemental analysis, FTIR, NMR and mass spectroscopy. The molecular geometry and spectroscopic properties of the complex as well as the free ligand have been calculated using the hybrid B3LYP method. The calculations predicted a distorted tetrahedral arrangement around Ag(I) ion. The vibrational spectra of the studied compounds have been assigned using potential energy distribution (PED). TD-DFT method was used to predict the electronic absorption spectra. The most intense absorption band showed a bathochromic shift and lowering of intensity in case of the complex (233.7 nm, f = 0.5604) compared to E3Q (λmax = 228.0 nm, f = 0.9072). The calculated 1H NMR chemical shifts using GIAO method showed good correlations with the experimental data. The computed dipole moment, polarizability and HOMO-LUMO energy gap were used to predict the nonlinear optical (NLO) properties. It is found that Ag(I) enhances the NLO activity. The natural bond orbital (NBO) analyses were used to elucidate the intramolecular charge transfer interactions causing stabilization for the investigated systems.

  19. 13C-flux analysis reveals NADPH-balancing transhydrogenation cycles in stationary phase of nitrogen-starving Bacillus subtilis.

    PubMed

    Rühl, Martin; Le Coq, Dominique; Aymerich, Stéphane; Sauer, Uwe

    2012-08-10

    In their natural habitat, microorganisms are typically confronted with nutritional limitations that restrict growth and force them to persevere in a stationary phase. Despite the importance of this phase, little is known about the metabolic state(s) that sustains it. Here, we investigate metabolically active but non-growing Bacillus subtilis during nitrogen starvation. In the absence of biomass formation as the major NADPH sink, the intracellular flux distribution in these resting B. subtilis reveals a large apparent catabolic NADPH overproduction of 5.0 ± 0.6 mmol g(-1)h(-1) that was partly caused by high pentose phosphate pathway fluxes. Combining transcriptome analysis, stationary (13)C-flux analysis in metabolic deletion mutants, (2)H-labeling experiments, and kinetic flux profiling, we demonstrate that about half of the catabolic excess NADPH is oxidized by two transhydrogenation cycles, i.e. isoenzyme pairs of dehydrogenases with different cofactor specificities that operate in reverse directions. These transhydrogenation cycles were constituted by the combined activities of the glyceraldehyde 3-phosphate dehydrogenases GapA/GapB and the malic enzymes MalS/YtsJ. At least an additional 6% of the overproduced NADPH is reoxidized by continuous cycling between ana- and catabolism of glutamate. Furthermore, in vitro enzyme data show that a not yet identified transhydrogenase could potentially reoxidize ∼20% of the overproduced NADPH. Overall, we demonstrate the interplay between several metabolic mechanisms that concertedly enable network-wide NADPH homeostasis under conditions of high catabolic NADPH production in the absence of cell growth in B. subtilis.

  20. 13C-flux Analysis Reveals NADPH-balancing Transhydrogenation Cycles in Stationary Phase of Nitrogen-starving Bacillus subtilis *

    PubMed Central

    Rühl, Martin; Le Coq, Dominique; Aymerich, Stéphane; Sauer, Uwe

    2012-01-01

    In their natural habitat, microorganisms are typically confronted with nutritional limitations that restrict growth and force them to persevere in a stationary phase. Despite the importance of this phase, little is known about the metabolic state(s) that sustains it. Here, we investigate metabolically active but non-growing Bacillus subtilis during nitrogen starvation. In the absence of biomass formation as the major NADPH sink, the intracellular flux distribution in these resting B. subtilis reveals a large apparent catabolic NADPH overproduction of 5.0 ± 0.6 mmol·g−1·h−1 that was partly caused by high pentose phosphate pathway fluxes. Combining transcriptome analysis, stationary 13C-flux analysis in metabolic deletion mutants, 2H-labeling experiments, and kinetic flux profiling, we demonstrate that about half of the catabolic excess NADPH is oxidized by two transhydrogenation cycles, i.e. isoenzyme pairs of dehydrogenases with different cofactor specificities that operate in reverse directions. These transhydrogenation cycles were constituted by the combined activities of the glyceraldehyde 3-phosphate dehydrogenases GapA/GapB and the malic enzymes MalS/YtsJ. At least an additional 6% of the overproduced NADPH is reoxidized by continuous cycling between ana- and catabolism of glutamate. Furthermore, in vitro enzyme data show that a not yet identified transhydrogenase could potentially reoxidize ∼20% of the overproduced NADPH. Overall, we demonstrate the interplay between several metabolic mechanisms that concertedly enable network-wide NADPH homeostasis under conditions of high catabolic NADPH production in the absence of cell growth in B. subtilis. PMID:22740702

  1. The response of streambed nitrogen cycling to spatial and temporal hyporheic vertical flux patterns and associated residence times

    NASA Astrophysics Data System (ADS)

    Briggs, M. A.; Lautz, L. K.; Hare, D. K.

    2011-12-01

    Small beaver dams enhance the development of patchy micro-environments along the stream corridor by trapping sediment and creating complex streambed morphologies. This generates intricate hyporheic flux patterns that govern the exchange of oxygen and redox sensitive solutes between the water column and the streambed, and exert control on the biogeochemical cycling of nitrogen. Specifically, flowpaths from the stream into the subsurface with low residence times create oxic conditions that favor nitrification, while flowpaths with longer residence times become anoxic and favor denitrification. To investigate these processes we collected vertical profiles of pore water upstream of two beaver dams in Wyoming, USA at nine locations with varied morphology. We sampled pore water to the 0.55 m depth every week for five weeks as stream discharge dropped by 45% and subsequently measured concentrations of dissolved oxygen and several redox sensitive solutes, including nitrate. Additionally, estimates of hyporheic flux along these nine vertical profiles through time were made using high-resolution heat data combined with 1-D heat transport modeling. The data show that areas of rapid, deep hyporheic flux at the glides immediately upstream of the dams were oxygen rich, and were generally sites of moderate net nitrification to at least the 0.35 m depth. These conditions were relatively steady over the study period. Hyporheic zones at sediment bars closest to the dams were hotspots of nitrate production to a depth of 0.35 m, with nitrate concentrations increasing by as much as 400% as vertical flux fell sharply and residence times increased over the study period. In contrast, shallow bars farther upstream from the dams showed increasing fluxes and decreased residence times, which caused a shift from net denitrification to net nitrification over the period at shallow depths. These results support previous work indicating threshold behavior of nitrogen cycling in response to

  2. Autophagic flux is highly active in early mitosis and differentially regulated throughout the cell cycle

    PubMed Central

    Li, Zhiyuan; Ji, Xinmiao; Wang, Dongmei; Liu, Juanjuan; Zhang, Xin

    2016-01-01

    Mitosis is a fast process that involves dramatic cellular remodeling and has a high energy demand. Whether autophagy is active or inactive during the early stages of mitosis in a naturally dividing cell is still debated. Here we aimed to use multiple assays to resolve this apparent discrepancy. Although the LC3 puncta number was reduced in mitosis, the four different cell lines we tested all have active autophagic flux in both interphase and mitosis. In addition, the autophagic flux was highly active in nocodazole-induced, double-thymidine synchronization released as well as naturally occurring mitosis in HeLa cells. Multiple autophagy proteins are upregulated in mitosis and the increased Beclin-1 level likely contributes to the active autophagic flux in early mitosis. It is interesting that although the autophagic flux is active throughout the cell cycle, early mitosis and S phase have relatively higher autophagic flux than G1 and late G2 phases, which might be helpful to degrade the damaged organelles and provide energy during S phase and mitosis. PMID:27213594

  3. Autophagic flux is highly active in early mitosis and differentially regulated throughout the cell cycle.

    PubMed

    Li, Zhiyuan; Ji, Xinmiao; Wang, Dongmei; Liu, Juanjuan; Zhang, Xin

    2016-06-28

    Mitosis is a fast process that involves dramatic cellular remodeling and has a high energy demand. Whether autophagy is active or inactive during the early stages of mitosis in a naturally dividing cell is still debated. Here we aimed to use multiple assays to resolve this apparent discrepancy. Although the LC3 puncta number was reduced in mitosis, the four different cell lines we tested all have active autophagic flux in both interphase and mitosis. In addition, the autophagic flux was highly active in nocodazole-induced, double-thymidine synchronization released as well as naturally occurring mitosis in HeLa cells. Multiple autophagy proteins are upregulated in mitosis and the increased Beclin-1 level likely contributes to the active autophagic flux in early mitosis. It is interesting that although the autophagic flux is active throughout the cell cycle, early mitosis and S phase have relatively higher autophagic flux than G1 and late G2 phases, which might be helpful to degrade the damaged organelles and provide energy during S phase and mitosis.

  4. A PROPOSED PARADIGM FOR SOLAR CYCLE DYNAMICS MEDIATED VIA TURBULENT PUMPING OF MAGNETIC FLUX IN BABCOCK–LEIGHTON-TYPE SOLAR DYNAMOS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hazra, Soumitra; Nandy, Dibyendu

    At present, the Babcock–Leighton flux transport solar dynamo models appear to be the most promising models for explaining diverse observational aspects of the sunspot cycle. The success of these flux transport dynamo models is largely dependent upon a single-cell meridional circulation with a deep equatorward component at the base of the Sun’s convection zone. However, recent observations suggest that the meridional flow may in fact be very shallow (confined to the top 10% of the Sun) and more complex than previously thought. Taken together, these observations raise serious concerns on the validity of the flux transport paradigm. By accounting formore » the turbulent pumping of magnetic flux, as evidenced in magnetohydrodynamic simulations of solar convection, we demonstrate that flux transport dynamo models can generate solar-like magnetic cycles even if the meridional flow is shallow. Solar-like periodic reversals are recovered even when meridional circulation is altogether absent. However, in this case, the solar surface magnetic field dynamics does not extend all the way to the polar regions. Very importantly, our results demonstrate that the Parker–Yoshimura sign rule for dynamo wave propagation can be circumvented in Babcock–Leighton dynamo models by the latitudinal component of turbulent pumping, which can generate equatorward propagating sunspot belts in the absence of a deep, equatorward meridional flow. We also show that variations in turbulent pumping coefficients can modulate the solar cycle amplitude and periodicity. Our results suggest the viability of an alternate magnetic flux transport paradigm—mediated via turbulent pumping—for sustaining solar-stellar dynamo action.« less

  5. Evidence of Microbial Regulation of Biogeochemical Cycles from a Study on Methane Flux and Land Use Change

    PubMed Central

    Nazaries, Loïc; Pan, Yao; Bodrossy, Levente; Baggs, Elizabeth M.; Millard, Peter; Murrell, J. Colin

    2013-01-01

    Microbes play an essential role in ecosystem functions, including carrying out biogeochemical cycles, but are currently considered a black box in predictive models and all global biodiversity debates. This is due to (i) perceived temporal and spatial variations in microbial communities and (ii) lack of ecological theory explaining how microbes regulate ecosystem functions. Providing evidence of the microbial regulation of biogeochemical cycles is key for predicting ecosystem functions, including greenhouse gas fluxes, under current and future climate scenarios. Using functional measures, stable-isotope probing, and molecular methods, we show that microbial (community diversity and function) response to land use change is stable over time. We investigated the change in net methane flux and associated microbial communities due to afforestation of bog, grassland, and moorland. Afforestation resulted in the stable and consistent enhancement in sink of atmospheric methane at all sites. This change in function was linked to a niche-specific separation of microbial communities (methanotrophs). The results suggest that ecological theories developed for macroecology may explain the microbial regulation of the methane cycle. Our findings provide support for the explicit consideration of microbial data in ecosystem/climate models to improve predictions of biogeochemical cycles. PMID:23624469

  6. Global correlation between surface heat fluxes and insolation in the 11-year solar cycle: The latitudinal effect

    NASA Astrophysics Data System (ADS)

    Volobuev, D. M.; Makarenko, N. G.

    2014-12-01

    Because of the small amplitude of insolation variations (1365.2-1366.6 W m-2 or 0.1%) from the 11-year solar cycle minimum to the cycle maximum and the structural complexity of the climatic dynamics, it is difficult to directly observe a solar signal in the surface temperature. The main difficulty is reduced to two factors: (1) a delay in the temperature response to external action due to thermal inertia, and (2) powerful internal fluctuations of the climatic dynamics suppressing the solar-driven component. In this work we take into account the first factor, solving the inverse problem of thermal conductivity in order to calculate the vertical heat flux from the measured temperature near the Earth's surface. The main model parameter—apparent thermal inertia—is calculated from the local seasonal extremums of temperature and albedo. We level the second factor by averaging mean annual heat fluxes in a latitudinal belt. The obtained mean heat fluxes significantly correlate with a difference between the insolation and optical depth of volcanic aerosol in the atmosphere, converted into a hindered heat flux. The calculated correlation smoothly increases with increasing latitude to 0.4-0.6, and the revealed latitudinal dependence is explained by the known effect of polar amplification.

  7. IRIS Toxicological Review of Trichloroacetic Acid (TCA) (Interagency Science Discussion Draft)

    EPA Science Inventory

    EPA is releasing the draft report, Toxicological Review of Trichloroacetic Acid (TCA), that was distributed to Federal agencies and White House Offices for comment during the Science Discussion step of the IRIS Assessment Development ...

  8. Multi-model analysis of terrestrial carbon cycles in Japan: limitations and implications of model calibration using eddy flux observations

    NASA Astrophysics Data System (ADS)

    Ichii, K.; Suzuki, T.; Kato, T.; Ito, A.; Hajima, T.; Ueyama, M.; Sasai, T.; Hirata, R.; Saigusa, N.; Ohtani, Y.; Takagi, K.

    2010-07-01

    Terrestrial biosphere models show large differences when simulating carbon and water cycles, and reducing these differences is a priority for developing more accurate estimates of the condition of terrestrial ecosystems and future climate change. To reduce uncertainties and improve the understanding of their carbon budgets, we investigated the utility of the eddy flux datasets to improve model simulations and reduce variabilities among multi-model outputs of terrestrial biosphere models in Japan. Using 9 terrestrial biosphere models (Support Vector Machine - based regressions, TOPS, CASA, VISIT, Biome-BGC, DAYCENT, SEIB, LPJ, and TRIFFID), we conducted two simulations: (1) point simulations at four eddy flux sites in Japan and (2) spatial simulations for Japan with a default model (based on original settings) and a modified model (based on model parameter tuning using eddy flux data). Generally, models using default model settings showed large deviations in model outputs from observation with large model-by-model variability. However, after we calibrated the model parameters using eddy flux data (GPP, RE and NEP), most models successfully simulated seasonal variations in the carbon cycle, with less variability among models. We also found that interannual variations in the carbon cycle are mostly consistent among models and observations. Spatial analysis also showed a large reduction in the variability among model outputs. This study demonstrated that careful validation and calibration of models with available eddy flux data reduced model-by-model differences. Yet, site history, analysis of model structure changes, and more objective procedure of model calibration should be included in the further analysis.

  9. In vitro anticancer effects of insect tea in TCA8113 cells.

    PubMed

    Qian, Yu; Li, Gui-Jie; Wang, Rui; Zhou, Ya-Lin; Sun, Peng; Zhao, Xin

    2014-01-01

    Insect tea is widely used a traditional drink or traditional Chinese medicine in China. This study was conducted with an aim to determine the in vitro anticancer effect of Insect tea in cancer cells. The anticancer effects of Insect tea were evaluated in human tongue carcinoma TCA8113 cells using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay, flow cytometry analysis, nuclear staining with 4,6-diamidino-2-phenylindole (DAPI), reverse transcription-polymerase chain reaction (RT-PCR) analysis, and western bolt assay. At 200 μg/mL, Insect tea inhibited the growth of TCA8113 cells by 80.7%, which was higher than the inhibition caused by 100 μg/mL Insect tea but lower than that of 200 μg/mL green tea. Compared to the control cancer cells, Insect tea significantly (P<0.05) induced apoptosis as determined by DAPI staining and flow cytometry analysis results. Insect tea significantly induced apoptosis in cancer cells by upregulating BAX, CASP3, CASP9 and downregulating BCL2. Genes encoding nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) were significantly downregulated by Insect tea, demonstrating its anti-inflammatory properties. Insect tea also exerted a great anti-metastasis effect on cancer cells as demonstrated by decreased expression of matrix metalloproteinase (MMP) genes and increased expression of tissue inhibitors of metalloproteinases (TIMPs). The results showed that Insect tea has good in vitro anticancer effects in TCA8113 cells, like green tea.

  10. Effects of drugs in subtoxic concentrations on the metabolic fluxes in human hepatoma cell line Hep G2

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Niklas, Jens; Noor, Fozia, E-mail: fozia.noor@mx.uni-saarland.d; Heinzle, Elmar

    2009-11-01

    Commonly used cytotoxicity assays assess the toxicity of a compound by measuring certain parameters which directly or indirectly correlate to the viability of the cells. However, the effects of a given compound at concentrations considerably below EC{sub 50} values are usually not evaluated. These subtoxic effects are difficult to identify but may eventually cause severe and costly long term problems such as idiosyncratic hepatotoxicity. We determined the toxicity of three hepatotoxic compounds, namely amiodarone, diclofenac and tacrine on the human hepatoma cell line Hep G2 using an online kinetic respiration assay and analysed the effects of subtoxic concentrations of thesemore » drugs on the cellular metabolism by using metabolic flux analysis. Several changes in the metabolism could be detected upon exposure to subtoxic concentrations of the test compounds. Upon exposure to diclofenac and tacrine an increase in the TCA-cycle activity was observed which could be a signature of an uncoupling of the oxidative phosphorylation. The results indicate that metabolic flux analysis could serve as an invaluable novel tool for the investigation of the effects of drugs. The described methodology enables tracking the toxicity of compounds dynamically using the respiration assay in a range of concentrations and the metabolic flux analysis permits interesting insights into the changes in the central metabolism of the cell upon exposure to drugs.« less

  11. Metabolomics and transcriptomics profiles reveal the dysregulation of the tricarboxylic acid cycle and related mechanisms in prostate cancer.

    PubMed

    Shao, Yaping; Ye, Guozhu; Ren, Shancheng; Piao, Hai-Long; Zhao, Xinjie; Lu, Xin; Wang, Fubo; Ma, Wang; Li, Jia; Yin, Peiyuan; Xia, Tian; Xu, Chuanliang; Yu, Jane J; Sun, Yinghao; Xu, Guowang

    2018-07-15

    Genetic alterations drive metabolic reprograming to meet increased biosynthetic precursor and energy demands for cancer cell proliferation and survival in unfavorable environments. A systematic study of gene-metabolite regulatory networks and metabolic dysregulation should reveal the molecular mechanisms underlying prostate cancer (PCa) pathogenesis. Herein, we performed gas chromatography-mass spectrometry (GC-MS)-based metabolomics and RNA-seq analyses in prostate tumors and matched adjacent normal tissues (ANTs) to elucidate the molecular alterations and potential underlying regulatory mechanisms in PCa. Significant accumulation of metabolic intermediates and enrichment of genes in the tricarboxylic acid (TCA) cycle were observed in tumor tissues, indicating TCA cycle hyperactivation in PCa tissues. In addition, the levels of fumarate and malate were highly correlated with the Gleason score, tumor stage and expression of genes encoding related enzymes and were significantly related to the expression of genes involved in branched chain amino acid degradation. Using an integrated omics approach, we further revealed the potential anaplerotic routes from pyruvate, glutamine catabolism and branched chain amino acid (BCAA) degradation contributing to replenishing metabolites for TCA cycle. Integrated omics techniques enable the performance of network-based analyses to gain a comprehensive and in-depth understanding of PCa pathophysiology and may facilitate the development of new and effective therapeutic strategies. © 2018 UICC.

  12. Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) mixture toxicity to the macrophytes Myriophyllum spicatum and Myriophyllum sibiricum in aquatic microcosms.

    PubMed

    Hanson, Mark L; Sibley, Paul K; Mabury, Scott A; Solomon, Keith R; Muir, Derek C G

    2002-02-21

    Trichloroacetic acid (TCA) and trifluoroacetic acid (TFA) have been detected together in environmental water samples throughout the world. TCA may enter into aquatic systems via rainout as the degradation product of chlorinated solvents, herbicide use, as a by-product of water disinfection and from emissions of spent bleach liquor of kraft pulp mills. Sources of TFA include degradation of hydrofluorocarbons (HFCs) refrigerants and pesticides. These substances are phytotoxic and widely distributed in aquatic environments. A study to assess the risk of a binary mixture of TCA and TFA to macrophytes in aquatic microcosms was conducted as part of a larger study on haloacetic acids. M. spicatum and M. sibiricum were exposed to 0.1, 1, 3 and 10 mg/l of both TCA and TFA (neutralized with sodium hydroxide) in replicate (n = 3) 12000 l aquatic microcosms for 49 days in an one-way analysis of variance design. Each microcosm was stocked with 14 individual apical shoots per species. The plants were sampled at regular intervals and assessed for the somatic endpoints of plant length, root growth, number of nodes and wet and dry mass and the biochemical endpoints of chlorophyll-a, chlorophyll-b, carotenoid content and citric acid levels. Results indicate that there were statistically significant effects of the TCA/TFA mixture on certain pigment concentrations immediately after the start of exposure (2-7 days), but the plants showed no signs of stress thereafter. These data suggest that TCA/TFA mixtures at environmentally relevant concentrations do not pose a significant risk to these aquatic macrophytes.

  13. Variability of North African hydroclimate during the last two climatic cycles: New insights from dust flux and provenance

    NASA Astrophysics Data System (ADS)

    Skonieczny, C.; McGee, D.; Bory, A. J. M.; Winckler, G.; Bradtmiller, L.; Bout-Roumazeilles, V.; Perala-Dewey, J.; Delattre, M.; Kinsley, C. W.; Polissar, P. J.; Malaizé, B.

    2016-12-01

    Every year, several hundred teragrams of dust are emitted from the Sahara and Sahel regions. These mineral particles sensitively track variations in atmospheric circulation and continental aridity. Sediments of the Northeastern Tropical Atlantic Ocean (NETAO) are fed by this intense dust supply and comprise unique long-term archives of past Saharan/Sahelian dust emissions. Past modifications of dust characteristics in these sedimentary archives can provide unique insights into changes in environmental conditions in source areas (aridity, weathering), as well as changes in atmospheric transport (wind direction and strength). Here we document changes in sediment supply to the NETAO using marine sediment core MD03-2705 (18°05N; 21°09W; 3085m water depth). This record is strategically located under the influence of seasonal dust plumes, and marine sediments of this area have revealed that past dust inputs were sensitive to global climate changes over the late Quaternary. We will focus our study on the last two climatic cycles (0-240ka), a period orbitally characterized by changes in the amplitude of both precession (MIS6-5 vs. MIS1-2) and ice volume (MIS 7 vs. MIS5). We will present, for the first time in this area, a continuous high-resolution record of dust, opal, carbonate and organic matter fluxes using 230Th-normalization. The constant flux proxy 230Thxs provides flux data that are not substantially affected by lateral advection or age model errors. These fluxes data will be complemented by grain-size, clay mineralogical and geochemical (major elements) analysis. By pairing dust flux measurements with complementary proxy data reflecting changes in aridity, wind strength and dust source, this study will provide a robust, continuous record of the magnitude and pacing of the North African hydroclimate variability through the last two climatic cycles. In particular, this long-term study will offer the opportunity to compare the well-documented North African climate

  14. A dynamo theory prediction for solar cycle 22: Sunspot number, radio flux, exospheric temperature, and total density at 400 km

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.; Hedin, A. E.

    1986-01-01

    Using the dynamo theory method to predict solar activity, a value for the smoothed sunspot number of 109 + or - 20 is obtained for solar cycle 22. The predicted cycle is expected to peak near December, 1990 + or - 1 year. Concommitantly, F(10.7) radio flux is expected to reach a smoothed value of 158 + or - 18 flux units. Global mean exospheric temperature is expected to reach 1060 + or - 50 K and global total average total thermospheric density at 400 km is expected to reach 4.3 x 10 to the -15th gm/cu cm + or - 25 percent.

  15. In vivo cardiac glucose metabolism in the high-fat fed mouse: Comparison of euglycemic–hyperinsulinemic clamp derived measures of glucose uptake with a dynamic metabolomic flux profiling approach

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kowalski, Greg M., E-mail: greg.kowalski@deakin.edu.au; De Souza, David P.; Risis, Steve

    Rationale: Cardiac metabolism is thought to be altered in insulin resistance and type 2 diabetes (T2D). Our understanding of the regulation of cardiac substrate metabolism and insulin sensitivity has largely been derived from ex vivo preparations which are not subject to the same metabolic regulation as in the intact heart in vivo. Studies are therefore required to examine in vivo cardiac glucose metabolism under physiologically relevant conditions. Objective: To determine the temporal pattern of the development of cardiac insulin resistance and to compare with dynamic approaches to interrogate cardiac glucose and intermediary metabolism in vivo. Methods and results: Studies were conducted to determine themore » evolution of cardiac insulin resistance in C57Bl/6 mice fed a high-fat diet (HFD) for between 1 and 16 weeks. Dynamic in vivo cardiac glucose metabolism was determined following oral administration of [U-{sup 13}C] glucose. Hearts were collected after 15 and 60 min and flux profiling was determined by measuring {sup 13}C mass isotopomers in glycolytic and tricarboxylic acid (TCA) cycle intermediates. Cardiac insulin resistance, determined by euglycemic–hyperinsulinemic clamp, was evident after 3 weeks of HFD. Despite the presence of insulin resistance, in vivo cardiac glucose metabolism following oral glucose administration was not compromised in HFD mice. This contrasts our recent findings in skeletal muscle, where TCA cycle activity was reduced in mice fed a HFD. Similar to our report in muscle, glucose derived pyruvate entry into the TCA cycle in the heart was almost exclusively via pyruvate dehydrogenase, with pyruvate carboxylase mediated anaplerosis being negligible after oral glucose administration. Conclusions: Under experimental conditions which closely mimic the postprandial state, the insulin resistant mouse heart retains the ability to stimulate glucose metabolism. - Highlights: • Insulin clamp was used to determine the evolution of

  16. Metabolic engineering in the biotechnological production of organic acids in the tricarboxylic acid cycle of microorganisms: Advances and prospects.

    PubMed

    Yin, Xian; Li, Jianghua; Shin, Hyun-Dong; Du, Guocheng; Liu, Long; Chen, Jian

    2015-11-01

    Organic acids, which are chemically synthesized, are also natural intermediates in the metabolic pathways of microorganisms, among which the tricarboxylic acid (TCA) cycle is the most crucial route existing in almost all living organisms. Organic acids in the TCA cycle include citric acid, α-ketoglutaric acid, succinic acid, fumaric acid, l-malic acid, and oxaloacetate, which are building-block chemicals with wide applications and huge markets. In this review, we summarize the synthesis pathways of these organic acids and review recent advances in metabolic engineering strategies that enhance organic acid production. We also propose further improvements for the production of organic acids with systems and synthetic biology-guided metabolic engineering strategies. Copyright © 2015 Elsevier Inc. All rights reserved.

  17. Decreased glycolytic and tricarboxylic acid cycle intermediates coincide with peripheral nervous system oxidative stress in a murine model of type 2 diabetes.

    PubMed

    Hinder, Lucy M; Vivekanandan-Giri, Anuradha; McLean, Lisa L; Pennathur, Subramaniam; Feldman, Eva L

    2013-01-01

    Diabetic neuropathy (DN) is the most common complication of diabetes and is characterized by distal-to-proximal loss of peripheral nerve axons. The idea of tissue-specific pathological alterations in energy metabolism in diabetic complications-prone tissues is emerging. Altered nerve metabolism in type 1 diabetes models is observed; however, therapeutic strategies based on these models offer limited efficacy to type 2 diabetic patients with DN. Therefore, understanding how peripheral nerves metabolically adapt to the unique type 2 diabetic environment is critical to develop disease-modifying treatments. In the current study, we utilized targeted liquid chromatography-tandem mass spectrometry (LC/MS/MS) to characterize the glycolytic and tricarboxylic acid (TCA) cycle metabolomes in sural nerve, sciatic nerve, and dorsal root ganglia (DRG) from male type 2 diabetic mice (BKS.Cg-m+/+Lepr(db); db/db) and controls (db/+). We report depletion of glycolytic intermediates in diabetic sural nerve and sciatic nerve (glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-bisphosphate (sural nerve only), 3-phosphoglycerate, 2-phosphoglycerate, phosphoenolpyruvate, and lactate), with no significant changes in DRG. Citrate and isocitrate TCA cycle intermediates were decreased in sural nerve, sciatic nerve, and DRG from diabetic mice. Utilizing LC/electrospray ionization/MS/MS and HPLC methods, we also observed increased protein and lipid oxidation (nitrotyrosine; hydroxyoctadecadienoic acids) in db/db tissue, with a proximal-to-distal increase in oxidative stress, with associated decreased aconitase enzyme activity. We propose a preliminary model, whereby the greater change in metabolomic profile, increase in oxidative stress, and decrease in TCA cycle enzyme activity may cause distal peripheral nerves to rely on truncated TCA cycle metabolism in the type 2 diabetes environment.

  18. Modeling and Depletion Simulations for a High Flux Isotope Reactor Cycle with a Representative Experiment Loading

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chandler, David; Betzler, Ben; Hirtz, Gregory John

    2016-09-01

    The purpose of this report is to document a high-fidelity VESTA/MCNP High Flux Isotope Reactor (HFIR) core model that features a new, representative experiment loading. This model, which represents the current, high-enriched uranium fuel core, will serve as a reference for low-enriched uranium conversion studies, safety-basis calculations, and other research activities. A new experiment loading model was developed to better represent current, typical experiment loadings, in comparison to the experiment loading included in the model for Cycle 400 (operated in 2004). The new experiment loading model for the flux trap target region includes full length 252Cf production targets, 75Se productionmore » capsules, 63Ni production capsules, a 188W production capsule, and various materials irradiation targets. Fully loaded 238Pu production targets are modeled in eleven vertical experiment facilities located in the beryllium reflector. Other changes compared to the Cycle 400 model are the high-fidelity modeling of the fuel element side plates and the material composition of the control elements. Results obtained from the depletion simulations with the new model are presented, with a focus on time-dependent isotopic composition of irradiated fuel and single cycle isotope production metrics.« less

  19. Dwell Time and Surface Parameter Effects on Removal of Silicone Oil From D6ac Steel Using TCA

    NASA Technical Reports Server (NTRS)

    Boothe, R. E.

    2003-01-01

    This study was conducted to evaluate the impact of dwell time, surface roughness, and the surface activation state on 1,1,1-trichloroethane's (TCA's) effectiveness for removing silicone oil from D6ac steel. Silicone-contaminated test articles were washed with TCA solvent, and then the surfaces were analyzed for residue, using Fourier transform infrared spectroscopy. The predominant factor affecting the ability to remove the silicone oil was surface roughness.

  20. Extraction-less, rapid assay for the direct detection of 2,4,6-trichloroanisole (TCA) in cork samples.

    PubMed

    Apostolou, Theofylaktos; Pascual, Nuria; Marco, M-Pilar; Moschos, Anastassios; Petropoulos, Anastassios; Kaltsas, Grigoris; Kintzios, Spyridon

    2014-07-01

    2,4,6-trichloroanisole (TCA), the cork taint molecule, has been the target of several analytical approaches over the few past years. In spite of the development of highly efficient and sensitive tools for its detection, ranging from advanced chromatography to biosensor-based techniques, a practical breakthrough for routine cork screening purposes has not yet been realized, in part due to the requirement of a lengthy extraction of TCA in organic solvents, mostly 12% ethanol and the high detectability required. In the present report, we present a modification of a previously reported biosensor system based on the measurement of the electric response of cultured fibroblast cells membrane-engineered with the pAb78 TCA-specific antibody. Samples were prepared by macerating cork tissue and mixing it directly with the cellular biorecognition elements, without any intervening extraction process. By using this novel approach, we were able to detect TCA in just five minutes at extremely low concentrations (down to 0.2 ppt). The novel biosensor offers a number of practical benefits, including a very considerable reduction in the total assay time by one day, and a full portability, enabling its direct employment for on-site, high throughput screening of cork in the field and production facilities, without requiring any type of supporting infrastructure. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. In vivo urea cycle flux distinguishes and correlates with phenotypic severity in disorders of the urea cycle

    PubMed Central

    Lee, Brendan; Yu, Hong; Jahoor, Farook; O'Brien, William; Beaudet, Arthur L.; Reeds, Peter

    2000-01-01

    Urea cycle disorders are a group of inborn errors of hepatic metabolism that result in often life-threatening hyperammonemia and hyperglutaminemia. Clinical and laboratory diagnosis of partial deficiencies during asymptomatic periods is difficult, and correlation of phenotypic severity with either genotype and/or in vitro enzyme activity is often imprecise. We hypothesized that stable isotopically determined in vivo rates of total body urea synthesis and urea cycle-specific nitrogen flux would correlate with both phenotypic severity and carrier status in patients with a variety of different enzymatic deficiencies of the urea cycle. We studied control subjects, patients, and their relatives with different enzymatic deficiencies affecting the urea cycle while consuming a low protein diet. On a separate occasion the subjects either received a higher protein intake or were treated with an alternative route medication sodium phenylacetate/benzoate (Ucephan), or oral arginine supplementation. Total urea synthesis from all nitrogen sources was determined from [18O]urea labeling, and the utilization of peripheral nitrogen was estimated from the relative isotopic enrichments of [15N]urea and [15N]glutamine during i.v. co-infusions of [5-(amide)15N]glutamine and [18O]urea. The ratio of the isotopic enrichments of 15N-urea/15N-glutamine distinguished normal control subjects (ratio = 0.42 ± 0.06) from urea cycle patients with late (0.17 ± 0.03) and neonatal (0.003 ± 0.007) presentations irrespective of enzymatic deficiency. This index of urea cycle activity also distinguished asymptomatic heterozygous carriers of argininosuccinate synthetase deficiency (0.22 ± 0.03), argininosuccinate lyase deficiency (0.35 ± 0.11), and partial ornithine transcarbamylase deficiency (0.26 ± 0.06) from normal controls. Administration of Ucephan lowered, and arginine increased, urea synthesis to the degree predicted from their respective rates of metabolism. The 15N-urea/15N-glutamine ratio

  2. TRACKING THE SOLAR CYCLE THROUGH IBEX OBSERVATIONS OF ENERGETIC NEUTRAL ATOM FLUX VARIATIONS AT THE HELIOSPHERIC POLES

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reisenfeld, D. B.; Janzen, P. H.; Bzowski, M., E-mail: dan.reisenfeld@umontana.edu, E-mail: paul.janzen@umontana.edu, E-mail: bzowski@cbk.waw.pl

    With seven years of Interstellar Boundary Explorer ( IBEX ) observations, from 2009 to 2015, we can now trace the time evolution of heliospheric energetic neutral atoms (ENAs) through over half a solar cycle. At the north and south ecliptic poles, the spacecraft attitude allows for continuous coverage of the ENA flux; thus, signal from these regions has much higher statistical accuracy and time resolution than anywhere else in the sky. By comparing the solar wind dynamic pressure measured at 1 au with the heliosheath plasma pressure derived from the observed ENA fluxes, we show that the heliosheath pressure measuredmore » at the poles correlates well with the solar cycle. The analysis requires time-shifting the ENA measurements to account for the travel time out and back from the heliosheath, which allows us to estimate the scale size of the heliosphere in the polar directions. We arrive at an estimated distance to the center of the ENA source region in the north of 220 au and in the south a distance of 190 au. We also find a good correlation between the solar cycle and the ENA energy spectra at the poles. In particular, the ENA flux for the highest IBEX energy channel (4.3 keV) is quite closely correlated with the areas of the polar coronal holes, in both the north and south, consistent with the notion that polar ENAs at this energy originate from pickup ions of the very high speed wind (∼700 km s{sup −1}) that emanates from polar coronal holes.« less

  3. Methylcitrate cycle defines the bactericidal essentiality of isocitrate lyase for survival of Mycobacterium tuberculosis on fatty acids

    PubMed Central

    Eoh, Hyungjin; Rhee, Kyu Y.

    2014-01-01

    Few mutations attenuate Mycobacterium tuberculosis (Mtb) more profoundly than deletion of its isocitrate lyases (ICLs). However, the basis for this attenuation remains incompletely defined. Mtb’s ICLs are catalytically bifunctional isocitrate and methylisocitrate lyases required for growth on even and odd chain fatty acids. Here, we report that Mtb’s ICLs are essential for survival on both acetate and propionate because of its methylisocitrate lyase (MCL) activity. Lack of MCL activity converts Mtb’s methylcitrate cycle into a “dead end” pathway that sequesters tricarboxylic acid (TCA) cycle intermediates into methylcitrate cycle intermediates, depletes gluconeogenic precursors, and results in defects of membrane potential and intrabacterial pH. Activation of an alternative vitamin B12-dependent pathway of propionate metabolism led to selective corrections of TCA cycle activity, membrane potential, and intrabacterial pH that specifically restored survival, but not growth, of ICL-deficient Mtb metabolizing acetate or propionate. These results thus resolve the biochemical basis of essentiality for Mtb’s ICLs and survival on fatty acids. PMID:24639517

  4. Annual Cycles of Deep-ocean, Biogeochemical Export Fluxes and Biological Pump Processes in Subtropical and Subantarctic Waters, Southwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nodder, S.; Chiswell, S.; Northcote, L.

    2016-02-01

    One of the key aspects of the global carbon cycle is the efficiency and spatio-temporal variability of the biological pump. In this paper, the annual cycles of particle fluxes, derived from moored sediment trap data collected from 2000-12 in subtropical (STW) and subantarctic waters (SAW), east of New Zealand, are presented. These observations are the most comprehensive export flux time-series from temperate Southern Hemisphere latitudes to date. With high levels of variability, fluxes in SAW were markedly lower than in STW, reflecting the picophytoplankton-dominated communities in the iron-limited, high nutrient-low chlorophyll SAW. Austral spring chlorophyll blooms in surface STW were near-synchronous with elevated fluxes of bio-siliceous, carbonate and organic carbon-rich materials to the deep ocean, probably facilitated by diatom sedimentation. Lithogenic fluxes were also high in STW, compared to SAW, reflecting proximity to the New Zealand landmass. In contrast, the highest biogenic fluxes in SAW occurred in spring when surface chlorophyll concentrations were low, while highest annual chlorophyll concentrations were in summer with no associated flux increase. We hypothesize that the high spring export in SAW occurs from subsurface chlorophyll accumulations that are not evident from remote-sensing satellites. This material was also rich in biogenic silica, perhaps related to the preferential export of diatoms and other silica-producing organisms, such as silicoflagellates and radiolarians. Particle fluxes in STW are similar to that of other mesotrophic to oligotrophic waters ( 6-7 mgC m-2 d-1), whereas export from SAW is below global averages ( 3 mgC m-2 d-1), and is characterized by carbonate-dominated and prominent bio-siliceous deposition.

  5. Measurement of the rates of acetyl-CoA hydrolysis and synthesis from acetate in rat hepatocytes and the role of these fluxes in substrate cycling.

    PubMed Central

    Crabtree, B; Gordon, M J; Christie, S L

    1990-01-01

    1. Acetyl-CoA hydrolysis, acetyl-CoA synthesis from acetate and several related fluxes were measured in rat hepatocytes. 2. In contrast with acetyl-CoA hydrolysis, most of the acetyl-CoA synthesis from acetate occurred in the mitochondria. 3. Acetyl-CoA hydrolysis was not significantly affected by 24 h starvation or (-)-hydroxycitrate. 4. In the cytoplasm there was a net flux of acetyl-CoA to acetate, and substrate cycling between acetate and acetyl-CoA in this compartment was very low, accounting for less than 0.1% of the total heat production by the animal. 5. A larger cycle, involving mitochondrial and cytoplasmic acetate and acetyl-CoA, may operate in fed animals, but would account for only approx 1% of total heat production. 6. It is proposed that the opposing fluxes of mitochondrial acetate utilization and cytoplasmic net acetate production may provide sensitivity, feedback and buffering, even when these fluxes are not linked to form a conventional substrate cycle. PMID:2396982

  6. The Martian hydrologic cycle - Effects of CO2 mass flux on global water distribution

    NASA Technical Reports Server (NTRS)

    James, P. B.

    1985-01-01

    The Martian CO2 cycle, which includes the seasonal condensation and subsequent sublimation of up to 30 percent of the planet's atmosphere, produces meridional winds due to the consequent mass flux of CO2. These winds currently display strong seasonal and hemispheric asymmetries due to the large asymmetries in the distribution of insolation on Mars. It is proposed that asymmetric meridional advection of water vapor on the planet due to these CO2 condensation winds is capable of explaining the observed dessication of Mars' south polar region at the current time. A simple model for water vapor transport is used to verify this hypothesis and to speculate on the effects of changes in orbital parameters on the seasonal water cycle.

  7. Annual cycles of deep-ocean biogeochemical export fluxes in subtropical and subantarctic waters, southwest Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Nodder, Scott D.; Chiswell, Stephen M.; Northcote, Lisa C.

    2016-04-01

    The annual cycles of particle fluxes derived from moored sediment trap data collected during 2000-2012 in subtropical (STW) and subantarctic waters (SAW) east of New Zealand are presented. These observations are the most comprehensive export flux time series from temperate Southern Hemisphere latitudes to date. With high levels of variability, fluxes in SAW were markedly lower than in STW, reflecting the picophytoplankton-dominated communities in the iron-limited, high nutrient-low chlorophyll SAW. Austral spring chlorophyll blooms in surface STW were near synchronous with elevated fluxes of bio-siliceous, carbonate, and organic carbon-rich materials to the deep ocean, probably facilitated by diatom and/or coccolithophorid sedimentation. Lithogenic fluxes were also high in STW, compared to SAW, reflecting proximity to the New Zealand landmass. In contrast, the highest biogenic fluxes in SAW occurred in spring when surface chlorophyll concentrations were low, while highest annual chlorophyll concentrations were in summer with no associated flux increase. We hypothesize that the high spring export in SAW results from subsurface chlorophyll accumulation that is not evident from remote-sensing satellites. This material was also rich in biogenic silica, perhaps related to the preferential export of diatoms and other silica-producing organisms, such as silicoflagellates and radiolarians. Organic carbon fluxes in STW are similar to that of other mesotrophic to oligotrophic waters (˜6-7 mg C m-2 d-1), whereas export from SAW is below the global average (˜3 mg C m-2 d-1). Regional differences in flux across the SW Pacific and Tasman region reflect variations in physical processes and ecosystem structure and function.

  8. The SeaFlux Turbulent Flux Dataset Version 1.0 Documentation

    NASA Technical Reports Server (NTRS)

    Clayson, Carol Anne; Roberts, J. Brent; Bogdanoff, Alec S.

    2012-01-01

    Under the auspices of the World Climate Research Programme (WCRP) Global Energy and Water cycle EXperiment (GEWEX) Data and Assessment Panel (GDAP), the SeaFlux Project was created to investigate producing a high-resolution satellite-based dataset of surface turbulent fluxes over the global oceans. The most current release of the SeaFlux product is Version 1.0; this represents the initial release of turbulent surface heat fluxes, associated near-surface variables including a diurnally varying sea surface temperature.

  9. How Much Flux does a Flux Transfer Event Transfer?

    NASA Astrophysics Data System (ADS)

    Fear, R. C.; Trenchi, L.; Coxon, J.; Milan, S. E.

    2016-12-01

    Flux transfer events are bursts of reconnection at the dayside magnetopause, which give rise to characteristic signatures that are observed by a range of magnetospheric/ionospheric instrumentation. Spacecraft situated near the magnetopause observe a bipolar variation in the component of the magnetic field normal to the magnetopause (BN); auroral instrumentation (either ground- or space-based) observe poleward moving auroral forms which indicate the convection of newly-opened flux into the polar cap, and ionospheric radars similarly observe pulsed ionospheric flows or poleward moving radar auroral forms. One outstanding problem is the fact that there is a fundamental mismatch between the estimates of the flux that is opened by each flux transfer event - in other words, their overall significance in the Dungey cycle. Spacecraft-based estimates of the flux content of individual FTEs correspond to each event transferring flux equivalent to approximately 1% of the open flux in the magnetosphere, whereas studies based on global-scale radar and auroral observations suggest this figure could be more like 10%. In the former case, flux transfer events would be a minor detail in the Dungey cycle, but in the latter they could be its main driver. We present observations of a conjunction between flux transfer event signatures observed by the Cluster spacecraft, and pulsed ionospheric flows observed by the SuperDARN network on the 8th February 2002. Over the course of an hour, a similar number of FTE signatures were observed by Cluster (at 13 MLT) and the Prince George radar (at 7 MLT). We argue that the reason for the existing mismatch in flux estimates is that implicit assumptions about flux transfer event structure lead to a major underestimate of the flux content based on spacecraft observations. If these assumptions are removed, a much better match is found.

  10. Continuous and batch cultures of Escherichia coli KJ134 for succinic acid fermentation: metabolic flux distributions and production characteristics.

    PubMed

    van Heerden, Carel D; Nicol, Willie

    2013-09-17

    Succinic acid (SA) has become a prominent biobased platform chemical with global production quantities increasing annually. Numerous genetically modified E. coli strains have been developed with the main aim of increasing the SA yield of the organic carbon source. In this study, a promising SA-producing strain, E. coli KJ134 [Biotechnol. Bioeng. 101:881-893, 2008], from the Department of Microbiology and Cell Science of the University of Florida was evaluated under continuous and batch conditions using D-glucose and CO2 in a mineral salt medium. Production characteristics entailing growth and maintenance rates, growth termination points and metabolic flux distributions under growth and non-growth conditions were determined. The culture remained stable for weeks under continuous conditions. Under growth conditions the redox requirements of the reductive tricarboxylic acid (TCA) cycle was solely balanced by acetic acid (AcA) production via the pyruvate dehydrogenase route resulting in a molar ratio of SA:AcA of two. A maximum growth rate of 0.22 h(-1) was obtained, while complete growth inhibition occurred at a SA concentration of 18 g L(-1). Batch culture revealed that high-yield succinate production (via oxidative TCA or glyoxylate redox balancing) occurred under non-growth conditions where a SA:AcA molar ratio of up to five was attained, with a final SA yield of 0.94 g g(-1). Growth termination of the batch culture was in agreement with that of the continuous culture. The maximum maintenance production rate of SA under batch conditions was found to be 0.6 g g(-1) h(-1). This is twice the maintenance rate observed in the continuous runs. The study revealed that the metabolic flux of E. coli KJ134 differs significantly for growth and non-growth conditions, with non-growth conditions resulting in higher SA:AcA ratios and SA yields. Bioreaction characteristics entailing growth and maintenance rates, as well as growth termination markers will guide future fermentor

  11. Water Cycle Variability over the Global Oceans Estimated Using Homogenized Reanalysis Fluxes

    NASA Astrophysics Data System (ADS)

    Robertson, F. R.; Bosilovich, M. G.; Roberts, J. B.

    2017-12-01

    Establishing consistent records of the global water cycle fluxes and their variations is particularly difficult over oceans where the density of in situ observations varies enormously with time, satellite retrievals of flux processes are sparse, and reanalyses are uncertain. The latter have the positive attribute of assimilating diverse observations to provide boundary fluxes and transports but are hindered by at least two factors: (1) the physical parameterizations are imperfect and, (2) the forcing data availability and quality vary greatly in time and, thus, can induce time-dependent, false signals of climate variability. Here we examine the prospects for homogenization of reanalysis records, that is, identifying and greatly minimizing non-physical signals. Our analysis focuses on the satellite era, 1980 to near present. The strategy involves three atmospheric reanalysis systems: (1) the NASA MERRA-2, (2) the newest reanalysis produced by the Japanese Meteorological Agency, JRA-55, and (3) the European Centre for Medium Range Weather Forecasts 20th Century reanalysis, ERA-20C. MERRA-2 and ERA-20C are also accompanied by 10-member AMIP integrations, and JRA-55 by a reanalysis using only conventional observations, JRA-55C. Differencing these latter integrations from the more comprehensive reanalyses helps provide a clearer picture of the impact of satellite observations by removing the effects of SST forcing. This facilitates the use of principal component analysis as a tool to identify and remove non-physical signals. We then use these homogenized E, P and moisture transports to examine the consistency of diagnostics of thermodynamic and hydrologic scaling, especially the P-E pattern amplification or the "wet-get-wetter, dry-get-drier" response. Prospects for further validation by new turbulent flux retrievals by satellite are discussed.

  12. Lipid-induced metabolic dysfunction in skeletal muscle.

    PubMed

    Muoio, Deborah M; Koves, Timothy R

    2007-01-01

    Insulin resistance is a hallmark of type 2 diabetes and commonly observed in other energy-stressed settings such as obesity, starvation, inactivity and ageing. Dyslipidaemia and 'lipotoxicity'--tissue accumulation of lipid metabolites-are increasingly recognized as important drivers of insulin resistant states. Mounting evidence suggests that lipid-induced metabolic dysfunction in skeletal muscle is mediated in large part by stress-activated serine kinases that interfere with insulin signal transduction. However, the metabolic and molecular events that connect lipid oversupply to stress kinase activation and glucose intolerance are as yet unclear. Application of transcriptomics and targeted mass spectrometry-based metabolomics tools has led to our finding that insulin resistance is a condition in which muscle mitochondria are persistently burdened with a heavy lipid load. As a result, high rates of beta-oxidation outpace metabolic flux through the TCA cycle, leading to accumulation of incompletely oxidized acyl-carnitine intermediates. In contrast, exercise training enhances mitochondrial performance, favouring tighter coupling between beta-oxidation and the TCA cycle, and concomitantly restores insulin sensitivity in animals fed a chronic high fat diet. The exercise-activated transcriptional co-activator, PGC1alpha, plays a key role in co-ordinating metabolic flux through these two intersecting metabolic pathways, and its suppression by overfeeding may contribute to obesity-associated mitochondrial dysfunction. Our emerging model predicts that muscle insulin resistance arises from mitochondrial lipid stress and a resultant disconnect between beta-oxidation and TCA cycle activity. Understanding this 'disconnect' and its molecular basis may lead to new therapeutic targets for combating metabolic disease.

  13. Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis.

    PubMed

    Morris, E Matthew; Meers, Grace M E; Koch, Lauren G; Britton, Steven L; Fletcher, Justin A; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C; Ibdah, Jamal A; Rector, R Scott; Thyfault, John P

    2016-10-01

    Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity.

  14. Aerobic capacity and hepatic mitochondrial lipid oxidation alters susceptibility for chronic high-fat diet-induced hepatic steatosis

    PubMed Central

    Morris, E. Matthew; Meers, Grace M. E.; Koch, Lauren G.; Britton, Steven L.; Fletcher, Justin A.; Fu, Xiaorong; Shankar, Kartik; Burgess, Shawn C.; Ibdah, Jamal A.; Rector, R. Scott

    2016-01-01

    Rats selectively bred for high capacity running (HCR) or low capacity running (LCR) display divergence for intrinsic aerobic capacity and hepatic mitochondrial oxidative capacity, both factors associated with susceptibility for nonalcoholic fatty liver disease. Here, we tested if HCR and LCR rats display differences in susceptibility for hepatic steatosis after 16 wk of high-fat diets (HFD) with either 45% or 60% of kcals from fat. HCR rats were protected against HFD-induced hepatic steatosis, whereas only the 60% HFD induced steatosis in LCR rats, as marked by a doubling of liver triglycerides. Hepatic complete fatty acid oxidation (FAO) and mitochondrial respiratory capacity were all lower in LCR compared with HCR rats. LCR rats also displayed lower hepatic complete and incomplete FAO in the presence of etomoxir, suggesting a reduced role for noncarnitine palmitoyltransferase-1-mediated lipid catabolism in LCR versus HCR rats. Hepatic complete FAO and mitochondrial respiration were largely unaffected by either chronic HFD; however, 60% HFD feeding markedly reduced 2-pyruvate oxidation, a marker of tricarboxylic acid (TCA) cycle flux, and mitochondrial complete FAO only in LCR rats. LCR rats displayed lower levels of hepatic long-chain acylcarnitines than HCR rats but maintained similar levels of hepatic acetyl-carnitine levels, further supporting lower rates of β-oxidation, and TCA cycle flux in LCR than HCR rats. Finally, only LCR rats displayed early reductions in TCA cycle genes after the acute initiation of a HFD. In conclusion, intrinsically high aerobic capacity confers protection against HFD-induced hepatic steatosis through elevated hepatic mitochondrial oxidative capacity. PMID:27600823

  15. Solar proton fluxes since 1956. [sunspot activity correlation

    NASA Technical Reports Server (NTRS)

    Reedy, R. C.

    1977-01-01

    The fluxes of protons emitted during solar flares since 1956 were evaluated. The depth-versus-activity profiles of Co-56 in several lunar rocks are consistent with the solar proton fluxes detected by experiments on several satellites. Only about 20% of the solar-proton-induced activities of Na-22 and Fe-55 in lunar rocks from early Apollo missions were produced by protons emitted from the sun during solar cycle 20 (1965-1975). The depth-versus-activity data for these radionuclides in several lunar rocks were used to determine the fluxes of protons during solar cycle 19 (1954-1964). The average proton fluxes for cycle 19 are about five times those for both the last million years and for cycle 20 and are about five times the previous estimate for cycle 19 based on neutron-monitor and radio ionospheric measurements. These solar-proton flux variations correlate with changes in sunspot activity.

  16. Annual cycles of mass flux and isotopic composition of pteropod shells settling into the deep Sargasso sea

    NASA Astrophysics Data System (ADS)

    Jasper, John P.; Deuser, Werner G.

    1993-04-01

    Mass fluxes and stable isotopic compositions ( δ18O and δ13C) pteropod shells collected during a 6-year series of 2-month sediment-trap deployments in the deep (3.2 km) Sargasso Sea provide information on annual population changes, habitat depths and life spans of thecosome pteropods (Euthecosomata). The flux of pteropod shells responds to the annual cycle of primary production in the upper ocean. Flux maxima of the shells (> 1 mm) of eight species occur from late winter through autumn. Seasonal changes in the hydrography of the upper water column are quite accurately recorded in the δ18O variations of six perennial species, which generally confirm the distinction between non-migratory ( Creseis acicula, Creseis virgula conica, and Diacria quadridentata) and diurnally migratory taxa ( Styliola subula, Cuvierina columnella, and Clio pyramidata). Isotopic records of C. acicula and C. virgula conica are consistent with shell formation above 50 m. The records of the migratory species reflect what appear to be average calcification depths of 50-75 m. Average annual δ13C variations reveal the annual cycles of primary production and stratification of near-surface waters. Adult life spans of the species studied appear to be no more than a few months. The results of this study should be useful in paleoceanographic reconstructions based on isotopic measurements of sedimentary pteropod shells.

  17. Induction of Tca8113 tumor cell apoptosis by icotinib is associated with reactive oxygen species mediated p38-MAPK activation.

    PubMed

    Yang, Cailing; Yan, Jianguo; Yuan, Guoyan; Zhang, Yinghua; Lu, Derong; Ren, Mingxin; Cui, Weigang

    2014-08-01

    Icotinib, a selective EGFR tyrosine kinase inhibitor (EGFR-TKI), has been shown to exhibit anti-tumor activity against several tumor cell lines. However, the exact molecular mechanism of icotinib's anti-tumor effect remains unknown. This study aims to examine the zytotoxic effect of icotinib on Tca8113 cells and its potential molecular mechanism. Icotinib significantly resulted in dose-dependent cell death as determined by MTT assay, accompanied by increased levels of Bax and DNA fragmentation. Icotinib could also induce Reactive Oxygen Species (ROS) generation. Further studies confirmed that scavenging of reactive oxygen species by N-acetyl-L-cysteine (NAC), and pharmacological inhibition of MAPK reversed icotinib-induced apoptosis in Tca8113 cells. Our data provide evidence that icotinib induces apoptosis, possibly via ROS-mediated MAPK pathway in Tca8113 cells.

  18. Solar Cycle variations in Earth's open flux content measured by the SuperDARN radar network

    NASA Astrophysics Data System (ADS)

    Imber, S. M.; Milan, S. E.; Lester, M.

    2013-09-01

    We present a long term study, from 1996 - 2012, of the latitude of the Heppner-Maynard Boundary (HMB) determined using the northern hemisphere SuperDARN radars. The HMB represents the equatorward extent of ionospheric convection and is here used as a proxy for the amount of open flux in the polar cap. The mean HMB latitude (measured at midnight) is found to be at 64 degrees during the entire period, with secondary peaks at lower latitudes during the solar maximum of 2003, and at higher latitudes during the recent extreme solar minimum of 2008-2011. We associate these large scale statistical variations in open flux content with solar cycle variations in the solar wind parameters leading to changes in the intensity of the coupling between the solar wind and the magnetosphere.

  19. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze–thaw cycles

    PubMed Central

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-01-01

    Freeze–thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice–liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree–water relations. We investigated water fluxes induced by ice formation during freeze–thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark’s living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze–thaw cycles in tree stems. PMID:26585223

  20. Oxaloacetate-to-malate conversion by mineral photoelectrochemistry: implications for the viability of the reductive tricarboxylic acid cycle in prebiotic chemistry

    NASA Astrophysics Data System (ADS)

    Guzman, Marcelo I.; Martin, Scot T.

    2008-10-01

    The carboxylic acids produced by the reductive tricarboxylic acid (rTCA) cycle are possibly a biosynthetic core of initial life, although several steps such as the reductive kinetics of oxaloacetate (OAA) to malate (MA) are problematic by conventional chemical routes. In this context, we studied the kinetics of this reaction as promoted by ZnS mineral photoelectrochemistry. The quantum efficiency φMA of MA production from the photoelectrochemical reduction of OAA followed φMA=0.13 [OAA] (2.1×10-3+[OAA])-1 and was independent of temperature (5 to 50°C). To evaluate the importance of this forward rate under a prebiotic scenario, we also studied the temperature-dependent rate of the backward thermal decarboxylation of OAA to pyruvate (PA), which followed an Arrhenius behavior as log (k-2)=11.74 4956/T, where k-2 is in units of s-1. These measured rates were employed in conjunction with the indirectly estimated carboxylation rate of PA to OAA to assess the possible importance of mineral photoelectrochemistry in the conversion of OAA to MA under several scenarios of prebiotic conditions on early Earth. As an example, our analysis shows that there is 90% efficiency with a forward velocity of 3 yr/cycle for the OAA→MA step of the rTCA cycle at 280 K. Efficiency and velocity both decrease for increasing temperature. These results suggest high viability for mineral photoelectrochemistry as an enzyme-free engine to drive the rTCA cycle through the early aeons of early Earth, at least for the investigated OAA→MA step.

  1. Expression of long non-coding RNA-HOTAIR in oral squamous cell carcinoma Tca8113 cells and its associated biological behavior

    PubMed Central

    Liu, Huawei; Li, Zhiyong; Wang, Chao; Feng, Lin; Huang, Haitao; Liu, Changkui; Li, Fengxia

    2016-01-01

    As a long noncoding RNA, HOX transcript antisense intergenic RNA (HOTAIR) is highly expressed in many types of tumors. However, its expression and function in oral squamous cell carcinoma (OSCC) cells and tissues remains largely unknown. We herein studied the biological functions of HOTAIR in OSCC Tca8113 cells. Real-time quantitative PCR showed that HOTAIR, p21 and p53 mRNA expressions in doxorubicin (DOX)-treated or γ-ray-irradiated Tca8113 cells were up-regulated. Knockdown of p53 expression inhibited DOX-induced HOTAIR up-regulation, suggesting that DNA damage-induced HOTAIR expression may be associated with p53. Transfection and CCK-8 assays showed that compared with the control group, overexpression of HOTAIR promoted the proliferation of Tca8113 cells, while interfering with its expression played an opposite role. Flow cytometry exhibited that HOTAIR overexpression decreased the rate of DOX-induced apoptosis. When HOTAIR expression was inhibited by siRNA, the proportions of cells in G2/M and S phases increased and decreased respectively. Meanwhile, the rate of DOX-induced apoptosis rose. DNA damage-induced HOTAIR expression facilitated the proliferation of Tca8113 cells and decreased their apoptosis. However, whether the up-regulation depends on p53 still needs in-depth studies. PMID:27904675

  2. IRIS Toxicological Review of Trichloroacetic Acid (TCA) ...

    EPA Pesticide Factsheets

    On September 24, 2009, the Toxicological Review of Trichloroacetic Acid (TCA) and the charge to external peer reviewers were released for external peer review and public comment. The Toxicological Review and charge were reviewed internally by EPA and by other federal agencies and White House Offices before public release. In the new IRIS process, introduced by the EPA Administrator, all written comments on IRIS assessments submitted by other federal agencies and White House Offices will be made publicly available. Accordingly, interagency comments and the interagency science consultation draft of the IRIS Toxicological Review of Trichloroacetic Acid and the charge to external peer reviewers are posted on this site. The draft Toxicological Review of Trichloroacetic Acid provides scientific support and rationale for the hazard identification and dose-response assessment pertaining to chronic exposure to trichloroacetic acid.

  3. Topology of modified helical gears and Tooth Contact Analysis (TCA) program

    NASA Technical Reports Server (NTRS)

    Litvin, Faydor L.; Zhang, Jiao

    1989-01-01

    The contents of this report covers: (1) development of optimal geometries for crowned helical gears; (2) a method for their generation; (3) tooth contact analysis (TCA) computer programs for the analysis of meshing and bearing contact of the crowned helical gears; and (4) modelling and simulation of gear shaft deflection. The developed method for synthesis was used to determine the optimal geometry for a crowned helical pinion surface and was directed to localize the bearing contact and guarantee favorable shape and a low level of transmission errors. Two new methods for generation of the crowned helical pinion surface are proposed. One is based on the application of a tool with a surface of revolution that slightly deviates from a regular cone surface. The tool can be used as a grinding wheel or as a shaver. The other is based on a crowning pinion tooth surface with predesigned transmission errors. The pinion tooth surface can be generated by a computer-controlled automatic grinding machine. The TCA program simulates the meshing and bearing contact of the misaligned gears. The transmission errors are also determined. The gear shaft deformation was modelled and investigated. It was found that the deflection of gear shafts has the same effect as gear misalignment.

  4. Annual Cycle of Surface Longwave Radiation

    NASA Technical Reports Server (NTRS)

    Mlynczak, Pamela E.; Smith, G. Louis; Wilber, Anne C.; Stackhouse, Paul W.

    2011-01-01

    The annual cycles of upward and downward longwave fluxes at the Earth s surface are investigated by use of the NASA/GEWEX Surface Radiation Budget Data Set. Because of the immense difference between the heat capacity of land and ocean, the surface of Earth is partitioned into these two categories. Principal component analysis is used to quantify the annual cycles. Over land, the first principal component describes over 95% of the variance of the annual cycle of the upward and downward longwave fluxes. Over ocean the first term describes more than 87% of these annual cycles. Empirical orthogonal functions show the corresponding geographical distributions of these cycles. Phase plane diagrams of the annual cycles of upward longwave fluxes as a function of net shortwave flux show the thermal inertia of land and ocean.

  5. Oceanic nitrogen cycling and N2O flux perturbations in the Anthropocene

    NASA Astrophysics Data System (ADS)

    Landolfi, A.; Somes, C. J.; Koeve, W.; Zamora, L. M.; Oschlies, A.

    2017-08-01

    There is currently no consensus on how humans are affecting the marine nitrogen (N) cycle, which limits marine biological production and CO2 uptake. Anthropogenic changes in ocean warming, deoxygenation, and atmospheric N deposition can all individually affect the marine N cycle and the oceanic production of the greenhouse gas nitrous oxide (N2O). However, the combined effect of these perturbations on marine N cycling, ocean productivity, and marine N2O production is poorly understood. Here we use an Earth system model of intermediate complexity to investigate the combined effects of estimated 21st century CO2 atmospheric forcing and atmospheric N deposition. Our simulations suggest that anthropogenic perturbations cause only a small imbalance to the N cycle relative to preindustrial conditions (˜+5 Tg N y-1 in 2100). More N loss from water column denitrification in expanded oxygen minimum zones (OMZs) is counteracted by less benthic denitrification, due to the stratification-induced reduction in organic matter export. The larger atmospheric N load is offset by reduced N inputs by marine N2 fixation. Our model predicts a decline in oceanic N2O emissions by 2100. This is induced by the decrease in organic matter export and associated N2O production and by the anthropogenically driven changes in ocean circulation and atmospheric N2O concentrations. After comprehensively accounting for a series of complex physical-biogeochemical interactions, this study suggests that N flux imbalances are limited by biogeochemical feedbacks that help stabilize the marine N inventory against anthropogenic changes. These findings support the hypothesis that strong negative feedbacks regulate the marine N inventory on centennial time scales.

  6. Skeletal muscle adaptation to fatty acid depends on coordinated actions of the PPARs and PGC1 alpha: implications for metabolic disease.

    PubMed

    Muoio, Deborah M; Koves, Timothy R

    2007-10-01

    Dyslipidemia and intramuscular accumulation of fatty acid metabolites are increasingly recognized as core features of obesity and type 2 diabetes. Emerging evidence suggests that normal physiological adaptations to a heavy lipid load depend on the coordinated actions of broad transcriptional regulators such as the peroxisome proliferator activated receptors (PPARs) and PPAR gamma coactivator 1 alpha (PGC1 alpha). The application of transcriptomics and targeted metabolic profiling tools based on mass spectrometry has led to our finding that lipid-induced insulin resistance is a condition in which upregulation of PPAR-targeted genes and high rates of beta-oxidation are not supported by a commensurate upregulation of tricarboxylic acid (TCA) cycle activity. In contrast, exercise training enhances mitochondrial performance, favoring tighter coupling between beta-oxidation and the TCA cycle, and concomitantly restores insulin sensitivity in animals fed a chronic high-fat diet. The exercise-activated transcriptional coactivator, PGC1 alpha, plays a key role in coordinating metabolic flux through these 2 intersecting metabolic pathways, and its suppression by overfeeding may contribute to diet-induced mitochondrial dysfunction. Our emerging model predicts that muscle insulin resistance arises from a mitochondrial disconnect between beta-oxidation and TCA cycle activity. Understanding of this "disconnect" and its molecular basis may lead to new therapeutic approaches to combatting metabolic disease.

  7. Cavitation and water fluxes driven by ice water potential in Juglans regia during freeze-thaw cycles.

    PubMed

    Charra-Vaskou, Katline; Badel, Eric; Charrier, Guillaume; Ponomarenko, Alexandre; Bonhomme, Marc; Foucat, Loïc; Mayr, Stefan; Améglio, Thierry

    2016-02-01

    Freeze-thaw cycles induce major hydraulic changes due to liquid-to-ice transition within tree stems. The very low water potential at the ice-liquid interface is crucial as it may cause lysis of living cells as well as water fluxes and embolism in sap conduits, which impacts whole tree-water relations. We investigated water fluxes induced by ice formation during freeze-thaw cycles in Juglans regia L. stems using four non-invasive and complementary approaches: a microdendrometer, magnetic resonance imaging, X-ray microtomography, and ultrasonic acoustic emissions analysis. When the temperature dropped, ice nucleation occurred, probably in the cambium or pith areas, inducing high water potential gradients within the stem. The water was therefore redistributed within the stem toward the ice front. We could thus observe dehydration of the bark's living cells leading to drastic shrinkage of this tissue, as well as high tension within wood conduits reaching the cavitation threshold in sap vessels. Ultrasonic emissions, which were strictly emitted only during freezing, indicated cavitation events (i.e. bubble formation) following ice formation in the xylem sap. However, embolism formation (i.e. bubble expansion) in stems was observed only on thawing via X-ray microtomography for the first time on the same sample. Ultrasonic emissions were detected during freezing and were not directly related to embolism formation. These results provide new insights into the complex process and dynamics of water movements and ice formation during freeze-thaw cycles in tree stems. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  8. Design principles of autocatalytic cycles constrain enzyme kinetics and force low substrate saturation at flux branch points

    PubMed Central

    Barenholz, Uri; Davidi, Dan; Reznik, Ed; Bar-On, Yinon; Antonovsky, Niv; Noor, Elad; Milo, Ron

    2017-01-01

    A set of chemical reactions that require a metabolite to synthesize more of that metabolite is an autocatalytic cycle. Here, we show that most of the reactions in the core of central carbon metabolism are part of compact autocatalytic cycles. Such metabolic designs must meet specific conditions to support stable fluxes, hence avoiding depletion of intermediate metabolites. As such, they are subjected to constraints that may seem counter-intuitive: the enzymes of branch reactions out of the cycle must be overexpressed and the affinity of these enzymes to their substrates must be relatively weak. We use recent quantitative proteomics and fluxomics measurements to show that the above conditions hold for functioning cycles in central carbon metabolism of E. coli. This work demonstrates that the topology of a metabolic network can shape kinetic parameters of enzymes and lead to seemingly wasteful enzyme usage. DOI: http://dx.doi.org/10.7554/eLife.20667.001 PMID:28169831

  9. The pulse of a montane ecosystem: coupled diurnal cycles in solar flux, snowmelt, evapotranspiration, groundwater, and streamflow at Sagehen Creek (Sierra Nevada, California)

    NASA Astrophysics Data System (ADS)

    Kirchner, James

    2016-04-01

    Forested catchments in the subalpine snow zone provide interesting opportunities to study the interplay between energy and water fluxes under seasonally variable degrees of forcing by transpiration and snowmelt. In such catchments, diurnal cycles in solar flux drive snowmelt and evapotranspiration, which in turn lead to diurnal cycles (with opposing phases) in groundwater levels. These in turn are linked to diurnal cycles in stream stage and discharge, which potentially provide a spatially integrated measure of snowmelt and evapotranspiration rates in the surrounding landscape. Here I analyze ecohydrological controls on diurnal stream and groundwater fluctuations induced by snowmelt and evapotranspiration (ET) at Sagehen Creek, in the Sierra Nevada mountains of California. There is a clear 6-hour lag between radiation forcing and the stream or groundwater response. This is not a travel-time delay, but instead a 90-degree dynamical phase lag arising from the integro-differential relationship between groundwater storage and recharge, ET, and streamflow. The time derivative of groundwater levels is strongly positively correlated with solar flux during snowmelt periods, reflecting snowmelt recharge to the riparian aquifer during daytime. Conversely, this derivative is strongly negatively correlated with solar flux during snow-free summer months, reflecting transpiration withdrawals from the riparian aquifer. As the snow cover disappears, the correlation between the solar flux and the time derivative of groundwater levels abruptly shifts from positive (snowmelt dominance) to negative (ET dominance). During this transition, the groundwater cycles briefly vanish when the opposing forcings (snowmelt and ET) are of equal magnitude, and thus cancel each other out. Stream stage fluctuations integrate these relationships over the altitude range of the catchment. Rates of rise and fall in stream stage are positively correlated with solar flux when the whole catchment is snow

  10. International Solar Cycle Studies (ISCS), "Solar Energy Flux Study: from the interior to the outer layer" — Working Group 1 report

    NASA Astrophysics Data System (ADS)

    Pap, Judit; Fröhlich, Claus

    The purpose of this report is to describe the research activities and plans of Working Group 1: "Solar Energy Flux Study: From the Interior to the Outer Layer" of the International Solar Cycle Study (ISCS), which is an international research organization operating under the auspices of the Scientific Committee on Solar-Terrestrial Physics (SCOSTEP). As part of the report, we also summarize the status of the measurements and results on the solar energy flux variations. The main objective of ISCS's Working Group 1 is to coordinate and support comprehensive international research of the variations in the solar energy flux during the rising portion and maximum of solar cycle 23. The research activities of ISCS's Working Group 1 will concentrate on the following tasks: (1) to measure and study the variations in the solar radiative and mass output and solar activity indices during the solar activity cycle, (2) to understand why the solar radiative and mass output and the solar activity indices vary during the solar cycle, and (3) to study the role of solar variability in solar-terrestrial changes and its contribution to global change. ISCS WG1 "Solar Energy Flux Study: From the Interior to the Outer Layer" has been divided into three panels: •| Panel 1: Variations in Total and Spectral Irradiance from Infrared to Far UV. Panel leaders: Martin Anklin of the Physikalisch-Meteorologishes Observatorium Davos, Switzerland (total irradiance), Gerard Thuillier of the Service d'Aeronomie-CNRS, Verrieres, France (visible and infrared), and Linton Floyd of the Naval Research Laboratory, Washington, DC, USA (ultraviolet). •| Panel 2: Variations in EUV, X-ray and Particle Fluxes. Panel leaders: Gerhard Schmidtke of Fraunhofer IPM, Freiburg, Germany and W. Kent Tobiska of FDC/Jet Propulsion Laboratory, Pasadena, CA, USA (EUV/XUV), and David Winningham of the Southwest Research Institute, San Antonio, TX, USA (particles). •| Panel 3: Solar Indices, Cosmogenic Isotopes, Solar

  11. Glutamate metabolism in HIV-1 infected macrophages: Role of HIV-1 Vpr.

    PubMed

    Datta, Prasun K; Deshmane, Satish; Khalili, Kamel; Merali, Salim; Gordon, John C; Fecchio, Chiara; Barrero, Carlos A

    2016-09-01

    HIV-1 infected macrophages play a significant role in the neuropathogenesis of AIDS. HIV-1 viral protein R (Vpr) not only facilitates HIV-1 infection but also contribute to long-lived persistence in macrophages. Our previous studies using SILAC-based proteomic analysis showed that the expression of critical metabolic enzymes in the glycolytic pathway and tricarboxylic acid (TCA) cycle were altered in response to Vpr expression in macrophages. We hypothesized that Vpr-induced modulation of glycolysis and TCA cycle regulates glutamate metabolism and release in HIV-1 infected macrophages. We assessed the amount of specific metabolites induced by Vpr and HIV-1 in macrophages at the intracellular and extracellular level in a time-dependent manner utilizing multiple reaction monitoring (MRM) targeted metabolomics. In addition, stable isotope-labeled glucose and an MRM targeted metabolomics assay were used to evaluate the de novo synthesis and release of glutamate in Vpr overexpressing macrophages and HIV-1 infected macrophages, throughout the metabolic flux of glycolytic pathway and TCA cycle activation. The metabolic flux studies demonstrated an increase in glucose uptake, glutamate release and accumulation of α-ketoglutarate (α-KG) and glutamine in the extracellular milieu in Vpr expressing and HIV-1 infected macrophages. Interestingly, glutamate pools and other intracellular intermediates (glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), citrate, malate, α-KG, and glutamine) showed a decreased trend except for fumarate, in contrast to the glutamine accumulation observed in the extracellular space in Vpr overexpressing macrophages. Our studies demonstrate that dysregulation of mitochondrial glutamate metabolism induced by Vpr in HIV-1 infected macrophages commonly seen, may contribute to neurodegeneration via excitotoxic mechanisms in the context of NeuroAIDS.

  12. Couplings between the seasonal cycles of surface thermodynamics and radiative fluxes in the semi-arid Sahel

    NASA Astrophysics Data System (ADS)

    Guichard, F.; Kergoat, L.; Mougin, E.; Timouk, F.; Bock, O.; Hiernaux, P.

    2009-04-01

    A good knowledge of surface fluxes and atmospheric low levels is central to improving our understanding of the West African monsoon. This study provides a quantitative analysis of the peculiar seasonal and diurnal cycles of surface thermodynamics and radiative fluxes encountered in Central Sahel. It is based on a multi-year dataset collected in the Malian Gourma over a sandy soil at 1.5°W-15.3°N (a site referred to as Agoufou) with an automated weather station and a sunphotometer (AERONET), complemented by observations from the AMMA field campaign. The seasonal cycle of this Tropical region is characterized by a broad maximum of temperature in May, following the first minimum of the solar zenith angle by a few weeks, when Agoufou lies within the West African Heat-Low, and a late summer maximum of equivalent potential temperature within the core of the monsoon season, around the second yearly maximum of solar zenith angle, as the temperature reaches its Summer minimum. More broadly, subtle balances between surface air temperature and moisture fields are found on a range of scales. For instance, during the monsoon, apart from August, their opposite daytime fluctuations (warming, drying) lead to an almost flat diurnal cycle of the equivalent potential temperature at the surface. This feature stands out in contrast to other more humid continental regions. Here, the strong dynamics associated with the transition from a drier hot Spring to a brief cooler wet tropical Summer climate involves very large transformations of the diurnal cycles. The Summer increase of surface net radiation, Rnet, is also strong; typically 10-day mean Rnet reaches about 5 times its Winter minimum (~30 W.m-2) in August (~150 W.m-2). A major feature revealed by observations is that this increase is mostly driven by modifications of the surface upwelling fluxes shaped by rainfall events and vegetation phenology (surface cooling and darkening), while the direct impact of atmospheric changes on

  13. Effect of tricarboxylic acid cycle regulator on carbon retention and organic component transformation during food waste composting.

    PubMed

    Lu, Qian; Zhao, Yue; Gao, Xintong; Wu, Junqiu; Zhou, Haixuan; Tang, Pengfei; Wei, Qingbin; Wei, Zimin

    2018-05-01

    Composting is an environment friendly method to recycling organic waste. However, with the increasing concern about greenhouse gases generated in global atmosphere, it is significant to reduce the emission of carbon dioxide (CO 2 ). This study analyzes tricarboxylic acid (TCA) cycle regulators on the effect of reducing CO 2 emission, and the relationship among organic component (OC) degradation and transformation and microorganism during composting. The results showed that adding adenosine tri-phosphate (ATP) and nicotinamide adenine dinucleotide (NADH) could enhance the transformation of OC and increase the diversity of microorganism community. Malonic acid (MA) as a competitive inhibitor could decrease the emission of CO 2 by inhibiting the TCA cycle. A structural equation model was established to explore effects of different OC and microorganism on humic acid (HA) concentration during composting. Furthermore, added MA provided an environmental benefit in reducing the greenhouse gas emission for manufacture sustainable products. Copyright © 2018 Elsevier Ltd. All rights reserved.

  14. Global Regulatory Mutations in csrA and rpoS Cause Severe Central Carbon Stress in Escherichia coli in the Presence of Acetate

    PubMed Central

    Wei, Bangdong; Shin, Sooan; LaPorte, David; Wolfe, Alan J.; Romeo, Tony

    2000-01-01

    The csrA gene encodes a small RNA-binding protein, which acts as a global regulator in Escherichia coli and other bacteria (T. Romeo, Mol. Microbiol. 29:1321–1330, 1998). Its key regulatory role in central carbon metabolism, both as an activator of glycolysis and as a potent repressor of glycogen biosynthesis and gluconeogenesis, prompted us to examine the involvement of csrA in acetate metabolism and the tricarboxylic acid (TCA) cycle. We found that growth of csrA rpoS mutant strains was very poor on acetate as a sole carbon source. Surprisingly, growth also was inhibited specifically by the addition of modest amounts of acetate to rich media (e.g., tryptone broth). Cultures grown in the presence of ≥25 mM acetate consisted substantially of glycogen biosynthesis (glg) mutants, which were no longer inhibited by acetate. Several classes of glg mutations were mapped to known and novel loci. Several hypotheses were examined to provide further insight into the effects of acetate on growth and metabolism in these strains. We determined that csrA positively regulates acs (acetyl-coenzyme A synthetase; Acs) expression and isocitrate lyase activity without affecting key TCA cycle enzymes or phosphotransacetylase. TCA cycle intermediates or pyruvate, but not glucose, galactose, or glycerol, restored growth and prevented the glg mutations in the presence of acetate. Furthermore, amino acid uptake was inhibited by acetate specifically in the csrA rpoS strain. We conclude that central carbon flux imbalance, inhibition of amino acid uptake, and a deficiency in acetate metabolism apparently are combined to cause metabolic stress by depleting the TCA cycle. PMID:10692369

  15. Simulations of a dynamic solar cycle and its effects on the interstellar boundary explorer ribbon and globally distributed energetic neutral atom flux

    DOE PAGES

    Zirnstein, E. J.; Heerikhuisen, J.; Pogorelov, N. V.; ...

    2015-04-23

    Observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs); this informs us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolution of themore » solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokol et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, these results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solar cycle, but rather with short-term fluctuations in the background plasma. And, while the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.« less

  16. SIMULATIONS OF A DYNAMIC SOLAR CYCLE AND ITS EFFECTS ON THE INTERSTELLAR BOUNDARY EXPLORER RIBBON AND GLOBALLY DISTRIBUTED ENERGETIC NEUTRAL ATOM FLUX

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zirnstein, E. J.; Heerikhuisen, J.; Pogorelov, N. V.

    2015-05-01

    Since 2009, observations by the Interstellar Boundary Explorer (IBEX) have vastly improved our understanding of the interaction between the solar wind (SW) and local interstellar medium through direct measurements of energetic neutral atoms (ENAs), which inform us about the heliospheric conditions that produced them. An enhanced feature of flux in the sky, the so-called IBEX ribbon, was not predicted by any global models before the first IBEX observations. A dominating theory of the origin of the ribbon, although still under debate, is a secondary charge-exchange process involving secondary ENAs originating from outside the heliopause. According to this mechanism, the evolutionmore » of the solar cycle should be visible in the ribbon flux. Therefore, in this paper we simulate a fully time-dependent ribbon flux, as well as globally distributed flux from the inner heliosheath (IHS), using time-dependent SW parameters from Sokół et al. as boundary conditions for our time-dependent heliosphere simulation. After post-processing the results to compute H ENA fluxes, our results show that the secondary ENA ribbon indeed should be time dependent, evolving with a period of approximately 11 yr, with differences depending on the energy and direction. Our results for the IHS flux show little periodic change with the 11 yr solar cycle, but rather with short-term fluctuations in the background plasma. While the secondary ENA mechanism appears to emulate several key characteristics of the observed IBEX ribbon, it appears that our simulation does not yet include all of the relevant physics that produces the observed ribbon.« less

  17. An early solar dynamo prediction: Cycle 23 is approximately cycle 22

    NASA Technical Reports Server (NTRS)

    Schatten, Kenneth H.; Pesnell, W. Dean

    1993-01-01

    In this paper, we briefly review the 'dynamo' and 'geomagnetic precursor' methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the magnification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar cycle, through the development of the 'Solar Dynamo Amplitude' (SODA) index. This index is sensitive to the magnetic flux trapped within the Sun's convection zone but insensitive to the phase of the solar cycle. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant flux. Using the present value of the SODA index, we estimate that the next cycle's smoothed peak activity will be about 210 +/- 30 solar flux units for the 10.7 cm radio flux and a sunspot number of 170 +/- 25. This suggests that solar cycle #23 will be large, comparable to cycle #22. The estimated peak is expected to occur near 1999.7 +/- 1 year. Since the current approach is novel (using data prior to solar minimum), these estimates may improve when the upcoming solar minimum is reached.

  18. Eddy Fluxes and Sensitivity of the Water Cycle to Spatial Resolution in Idealized Regional Aquaplanet Model Simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hagos, Samson M.; Leung, Lai-Yung R.; Gustafson, William I.

    2014-02-28

    A multi-scale moisture budget analysis is used to identify the mechanisms responsible for the sensitivity of the water cycle to spatial resolution using idealized regional aquaplanet simulations. In the higher resolution simulations, moisture transport by eddies fluxes dry the boundary layer enhancing evaporation and precipitation. This effect of eddies, which is underestimated by the physics parameterizations in the low-resolution simulations, is found to be responsible for the sensitivity of the water cycle both directly, and through its upscale effect, on the mean circulation. Correlations among moisture transport by eddies at adjacent ranges of scales provides the potential for reducing thismore » sensitivity by representing the unresolved eddies by their marginally resolved counterparts.« less

  19. Modeling and Simulations for the High Flux Isotope Reactor Cycle 400

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ilas, Germina; Chandler, David; Ade, Brian J

    2015-03-01

    A concerted effort over the past few years has been focused on enhancing the core model for the High Flux Isotope Reactor (HFIR), as part of a comprehensive study for HFIR conversion from high-enriched uranium (HEU) to low-enriched uranium (LEU) fuel. At this time, the core model used to perform analyses in support of HFIR operation is an MCNP model for the beginning of Cycle 400, which was documented in detail in a 2005 technical report. A HFIR core depletion model that is based on current state-of-the-art methods and nuclear data was needed to serve as reference for the designmore » of an LEU fuel for HFIR. The recent enhancements in modeling and simulations for HFIR that are discussed in the present report include: (1) revision of the 2005 MCNP model for the beginning of Cycle 400 to improve the modeling data and assumptions as necessary based on appropriate primary reference sources HFIR drawings and reports; (2) improvement of the fuel region model, including an explicit representation for the involute fuel plate geometry that is characteristic to HFIR fuel; and (3) revision of the Monte Carlo-based depletion model for HFIR in use since 2009 but never documented in detail, with the development of a new depletion model for the HFIR explicit fuel plate representation. The new HFIR models for Cycle 400 are used to determine various metrics of relevance to reactor performance and safety assessments. The calculated metrics are compared, where possible, with measurement data from preconstruction critical experiments at HFIR, data included in the current HFIR safety analysis report, and/or data from previous calculations performed with different methods or codes. The results of the analyses show that the models presented in this report provide a robust and reliable basis for HFIR analyses.« less

  20. Carbon Dioxide Flux from Rice Paddy Soils in Central China: Effects of Intermittent Flooding and Draining Cycles

    PubMed Central

    Liu, Yi; Wan, Kai-yuan; Tao, Yong; Li, Zhi-guo; Zhang, Guo-shi; Li, Shuang-lai; Chen, Fang

    2013-01-01

    A field experiment was conducted to (i) examine the diurnal and seasonal soil carbon dioxide (CO2) fluxes pattern in rice paddy fields in central China and (ii) assess the role of floodwater in controlling the emissions of CO2 from soil and floodwater in intermittently draining rice paddy soil. The soil CO2 flux rates ranged from −0.45 to 8.62 µmol.m−2.s−1 during the rice-growing season. The net effluxes of CO2 from the paddy soil were lower when the paddy was flooded than when it was drained. The CO2 emissions for the drained conditions showed distinct diurnal variation with a maximum efflux observed in the afternoon. When the paddy was flooded, daytime soil CO2 fluxes reversed with a peak negative efflux just after midday. In draining/flooding alternating periods, a sudden pulse-like event of rapidly increasing CO2 efflux occured in response to re-flooding after draining. Correlation analysis showed a negative relation between soil CO2 flux and temperature under flooded conditions, but a positive relation was found under drained conditions. The results showed that draining and flooding cycles play a vital role in controlling CO2 emissions from paddy soils. PMID:23437170

  1. Linus cycle calculations including plasma transport and resistive flux loss in an incompressible liner

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Quimby, D.C.; Hoffman, A.L.; Vlases, G.C.

    1980-08-01

    In the LINUS fusion reactor concept, a rotating liquid metal liner is used for reversible mechanical compression of thermonuclear plasmas, where a vacuum field buffer zone is used between the plasma and wall to reduce transport losses. A one-dimensional plasma transport and burn code, including incompressible liner dynamics with heat transfer and temperature dependent flux diffusion in the liquid metal, is used to model LINUS cycles. The effects of compressibility are treated as a perturbation. Numerical coefficients are derived for simple LINUS scaling laws. The particular case of plasma contact with the liquid metal is studied to determine the effectmore » on LINUS performance.« less

  2. Metabolic flux profiling of recombinant protein secreting Pichia pastoris growing on glucose:methanol mixtures

    PubMed Central

    2012-01-01

    Background The methylotrophic yeast Pichia pastoris has emerged as one of the most promising yeast hosts for the production of heterologous proteins. Mixed feeds of methanol and a multicarbon source instead of methanol as sole carbon source have been shown to improve product productivities and alleviate metabolic burden derived from protein production. Nevertheless, systematic quantitative studies on the relationships between the central metabolism and recombinant protein production in P. pastoris are still rather limited, particularly when growing this yeast on mixed carbon sources, thus hampering future metabolic network engineering strategies for improved protein production. Results The metabolic flux distribution in the central metabolism of P. pastoris growing on a mixed feed of glucose and methanol was analyzed by Metabolic Flux Analysis (MFA) using 13C-NMR-derived constraints. For this purpose, we defined new flux ratios for methanol assimilation pathways in P. pastoris cells growing on glucose:methanol mixtures. By using this experimental approach, the metabolic burden caused by the overexpression and secretion of a Rhizopus oryzae lipase (Rol) in P. pastoris was further analyzed. This protein has been previously shown to trigger the unfolded protein response in P. pastoris. A series of 13C-tracer experiments were performed on aerobic chemostat cultivations with a control and two different Rol producing strains growing at a dilution rate of 0.09 h−1 using a glucose:methanol 80:20 (w/w) mix as carbon source. The MFA performed in this study reveals a significant redistristribution of carbon fluxes in the central carbon metabolism when comparing the two recombinant strains vs the control strain, reflected in increased glycolytic, TCA cycle and NADH regeneration fluxes, as well as higher methanol dissimilation rates. Conclusions Overall, a further 13C-based MFA development to characterise the central metabolism of methylotrophic yeasts when growing on mixed

  3. Glial dysfunction in abstinent methamphetamine abusers

    PubMed Central

    Sailasuta, Napapon; Abulseoud, Osama; Harris, Kent C; Ross, Brian D

    2010-01-01

    Persistent neurochemical abnormalities in frontal brain structures are believed to result from methamphetamine use. We developed a localized 13C magnetic resonance spectroscopy (MRS) assay on a conventional MR scanner, to quantify selectively glial metabolic flux rate in frontal brain of normal subjects and a cohort of recovering abstinent methamphetamine abusers. Steady-state bicarbonate concentrations were similar, between 11 and 15 mmol/L in mixed gray-white matter of frontal brain of normal volunteers and recovering methamphetamine-abusing subjects (P>0.1). However, glial 13C-bicarbonate production rate from [1-13C]acetate, equating with glial tricarboxylic acid (TCA) cycle rate, was significantly reduced in frontal brain of abstinent methamphetamine-addicted women (methamphetamine 0.04 μmol/g per min (N=5) versus controls 0.11 μmol/g per min (N=5), P=0.001). This is equivalent to 36% of the normal glial TCA cycle rate. Severe reduction in glial TCA cycle rate that normally comprises 10% of total cerebral metabolic rate may impact operation of the neuronal glial glutamate cycle and result in accumulation of frontal brain glutamate, as observed in these recovering methamphetamine abusers. Although these are the first studies to define directly an abnormality in glial metabolism in human methamphetamine abuse, sequential studies using analogous 13C MRS methods may determine ‘cause and effect' between glial failure and neuronal injury. PMID:20040926

  4. Metabolic profiles of exercise in patients with McArdle disease or mitochondrial myopathy

    PubMed Central

    Sharma, Rohit; Tadvalkar, Laura; Clish, Clary B.; Haller, Ronald G.; Mootha, Vamsi K.

    2017-01-01

    McArdle disease and mitochondrial myopathy impair muscle oxidative phosphorylation (OXPHOS) by distinct mechanisms: the former by restricting oxidative substrate availability caused by blocked glycogen breakdown, the latter because of intrinsic respiratory chain defects. We applied metabolic profiling to systematically interrogate these disorders at rest, when muscle symptoms are typically minimal, and with exercise, when symptoms of premature fatigue and potential muscle injury are unmasked. At rest, patients with mitochondrial disease exhibit elevated lactate and reduced uridine; in McArdle disease purine nucleotide metabolites, including xanthine, hypoxanthine, and inosine are elevated. During exercise, glycolytic intermediates, TCA cycle intermediates, and pantothenate expand dramatically in both mitochondrial disease and control subjects. In contrast, in McArdle disease, these metabolites remain unchanged from rest; but urea cycle intermediates are increased, likely attributable to increased ammonia production as a result of exaggerated purine degradation. Our results establish skeletal muscle glycogen as the source of TCA cycle expansion that normally accompanies exercise and imply that impaired TCA cycle flux is a central mechanism of restricted oxidative capacity in this disorder. Finally, we report that resting levels of long-chain triacylglycerols in mitochondrial myopathy correlate with the severity of OXPHOS dysfunction, as indicated by the level of impaired O2 extraction from arterial blood during peak exercise. Our integrated analysis of exercise and metabolism provides unique insights into the biochemical basis of these muscle oxidative defects, with potential implications for their clinical management. PMID:28716914

  5. Load and Pi control flux through the branched kinetic cycle of myosin V.

    PubMed

    Kad, Neil M; Trybus, Kathleen M; Warshaw, David M

    2008-06-20

    Myosin V is a processive actin-based motor protein that takes multiple 36-nm steps to deliver intracellular cargo to its destination. In the laser trap, applied load slows myosin V heavy meromyosin stepping and increases the probability of backsteps. In the presence of 40 mm phosphate (P(i)), both forward and backward steps become less load-dependent. From these data, we infer that P(i) release commits myosin V to undergo a highly load-dependent transition from a state in which ADP is bound to both heads and its lead head trapped in a pre-powerstroke conformation. Increasing the residence time in this state by applying load increases the probability of backstepping or detachment. The kinetics of detachment indicate that myosin V can detach from actin at two distinct points in the cycle, one of which is turned off by the presence of P(i). We propose a branched kinetic model to explain these data. Our model includes P(i) release prior to the most load-dependent step in the cycle, implying that P(i) release and load both act as checkpoints that control the flux through two parallel pathways.

  6. The Solar Cycle.

    PubMed

    Hathaway, David H

    The solar cycle is reviewed. The 11-year cycle of solar activity is characterized by the rise and fall in the numbers and surface area of sunspots. A number of other solar activity indicators also vary in association with the sunspots including; the 10.7 cm radio flux, the total solar irradiance, the magnetic field, flares and coronal mass ejections, geomagnetic activity, galactic cosmic ray fluxes, and radioisotopes in tree rings and ice cores. Individual solar cycles are characterized by their maxima and minima, cycle periods and amplitudes, cycle shape, the equatorward drift of the active latitudes, hemispheric asymmetries, and active longitudes. Cycle-to-cycle variability includes the Maunder Minimum, the Gleissberg Cycle, and the Gnevyshev-Ohl (even-odd) Rule. Short-term variability includes the 154-day periodicity, quasi-biennial variations, and double-peaked maxima. We conclude with an examination of prediction techniques for the solar cycle and a closer look at cycles 23 and 24. Supplementary material is available for this article at 10.1007/lrsp-2015-4.

  7. DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cline, Gary W., E-mail: gary.cline@yale.edu; Department of Surgery, University of Minnesota-Twin Cities, Minneapolis, MN 55455; Pongratz, Rebecca L.

    Highlights: Black-Right-Pointing-Pointer We studied media effects on mechanisms of insulin secretion of INS-1 cells. Black-Right-Pointing-Pointer Insulin secretion was higher in DMEM than KRB despite identical ATP synthesis rates. Black-Right-Pointing-Pointer Insulin secretion rates correlated with rates of anaplerosis and TCA cycle. Black-Right-Pointing-Pointer Mitochondria metabolism and substrate cycles augment secretion signal of ATP. -- Abstract: Mechanistic models of glucose stimulated insulin secretion (GSIS) established in minimal media in vitro, may not accurately describe the complexity of coupling metabolism with insulin secretion that occurs in vivo. As a first approximation, we have evaluated metabolic pathways in a typical growth media, DMEM as amore » surrogate in vivo medium, for comparison to metabolic fluxes observed under the typical experimental conditions using the simple salt-buffer of KRB. Changes in metabolism in response to glucose and amino acids and coupling to insulin secretion were measured in INS-1 832/13 cells. Media effects on mitochondrial function and the coupling efficiency of oxidative phosphorylation were determined by fluorometrically measured oxygen consumption rates (OCRs) combined with {sup 31}P NMR measured rates of ATP synthesis. Substrate preferences and pathways into the TCA cycle, and the synthesis of mitochondrial 2nd messengers by anaplerosis were determined by {sup 13}C NMR isotopomer analysis of the fate of [U-{sup 13}C] glucose metabolism. Despite similar incremental increases in insulin secretion, the changes of OCR in response to increasing glucose from 2.5 to 15 mM were blunted in DMEM relative to KRB. Basal and stimulated rates of insulin secretion rates were consistently higher in DMEM, while ATP synthesis rates were identical in both DMEM and KRB, suggesting greater mitochondrial uncoupling in DMEM. The relative rates of anaplerosis, and hence synthesis and export of 2nd messengers from the mitochondria

  8. Impact of a Regional Drought on Terrestrial Carbon Fluxes and Atmospheric Carbon: Results from a Coupled Carbon Cycle Model

    NASA Technical Reports Server (NTRS)

    Lee, Eunjee; Koster, Randal D.; Ott, Lesley E.; Weir, Brad; Mahanama, Sarith; Chang, Yehui; Zeng, Fan-Wei

    2017-01-01

    Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes, and the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Results show a sequence of changes in carbon fluxes and atmospheric CO2, induced by the drought. The relative contributions of meteorological changes to the neighboring carbon dynamics are also presented. The coupled modeling approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

  9. Protein-bound NAD(P)H Lifetime is Sensitive to Multiple Fates of Glucose Carbon.

    PubMed

    Sharick, Joe T; Favreau, Peter F; Gillette, Amani A; Sdao, Sophia M; Merrins, Matthew J; Skala, Melissa C

    2018-04-03

    While NAD(P)H fluorescence lifetime imaging (FLIM) can detect changes in flux through the TCA cycle and electron transport chain (ETC), it remains unclear whether NAD(P)H FLIM is sensitive to other potential fates of glucose. Glucose carbon can be diverted from mitochondria by the pentose phosphate pathway (via glucose 6-phosphate dehydrogenase, G6PDH), lactate production (via lactate dehydrogenase, LDH), and rejection of carbon from the TCA cycle (via pyruvate dehydrogenase kinase, PDK), all of which can be upregulated in cancer cells. Here, we demonstrate that multiphoton NAD(P)H FLIM can be used to quantify the relative concentrations of recombinant LDH and malate dehydrogenase (MDH) in solution. In multiple epithelial cell lines, NAD(P)H FLIM was also sensitive to inhibition of LDH and PDK, as well as the directionality of LDH in cells forced to use pyruvate versus lactate as fuel sources. Among the parameters measurable by FLIM, only the lifetime of protein-bound NAD(P)H (τ 2 ) was sensitive to these changes, in contrast to the optical redox ratio, mean NAD(P)H lifetime, free NAD(P)H lifetime, or the relative amount of free and protein-bound NAD(P)H. NAD(P)H τ 2 offers the ability to non-invasively quantify diversions of carbon away from the TCA cycle/ETC, which may support mechanisms of drug resistance.

  10. In vivo carbon-edited detection with proton echo-planar spectroscopic imaging (ICED PEPSI): [3,4-(13)CH(2)]glutamate/glutamine tomography in rat brain.

    PubMed

    Hyder, F; Renken, R; Rothman, D L

    1999-12-01

    A method for in vivo carbon-edited detection with proton echo-planar spectroscopic imaging (ICED PEPSI) is described. This method is composed of an echo-planar based acquisition implemented with (13)C-(1)H J editing spectroscopy and is intended for high temporal and spatial resolution in vivo spectroscopic imaging of (13)C turnover, from D-[1,6-(13)C]glucose to glutamate and glutamine, in the brain. At a static magnetic field strength of 7 T, both in vitro and in vivo chemical shift imaging data are presented with a spatial resolution of 8 microL (i.e., 1.25 x 1.25 x 5.00 mm(3)) and a maximum spectral bandwidth of 5.2 ppm in (1)H. Chemical shift imaging data acquired every 11 minutes allowed detection of regional [4-(13)CH(2)]glutamate turnover in rat brain. The [4-(13)CH(2)]glutamate turnover curves, which can be converted to tricarboxylic acid cycle fluxes, showed that the tricarboxylic acid cycle flux (V(TCA)) in pure gray and white matter can range from 1.2 +/- 0.2 to 0.5 +/- 0.1 micromol/g/min, respectively, for morphine-anesthetized rats. The mean cortical V(TCA) from 32 voxels of 1.0 +/- 0.3 micromol/g/min (N = 3) is in excellent agreement with previous localized measurements that have demonstrated that V(TCA) can range from 0.9-1.1 micromol/g/min under identical anesthetized conditions. Magn Reson Med 42:997-1003, 1999. Copyright 1999 Wiley-Liss, Inc.

  11. DOE Office of Scientific and Technical Information (OSTI.GOV)

    He, Lian; Xiu, Yu; Jones, J. Andrew

    Microbial fermentation conditions are dynamic, due to transcriptional induction, nutrient consumption, or changes to incubation conditions. In this paper, 13C-metabolic flux analysis was used to characterize two violacein-producing E. coli strains with vastly different productivities, and to profile their metabolic adjustments resulting from external perturbations during fermentation. The two strains were first grown at 37 °C in stage 1, and then the temperature was transitioned to 20 °C in stage 2 for the optimal expression of the violacein synthesis pathway. After induction, violacein production was minimal in stage 3, but accelerated in stage 4 (early production phase) and 5 (latemore » production phase) in the high producing strain, reaching a final concentration of 1.5 mmol/L. On the contrary, ~0.02 mmol/L of violacein was obtained from the low producing strain. To have a snapshot of the temporal metabolic changes in each stage, we performed 13C-MFA via isotopomer analysis of fast-turnover free metabolites. The results indicate strikingly stable flux ratios in the central metabolism throughout the early growth stages. In the late stages, however, the high producer rewired its flux distribution significantly, which featured an upregulated pentose phosphate pathway and TCA cycle, reflux from acetate utilization, negligible anabolic fluxes, and elevated maintenance loss, to compensate for nutrient depletion and drainage of some building blocks due to violacein overproduction. The low producer with stronger promoters shifted its relative fluxes in stage 5 by enhancing the flux through the TCA cycle and acetate overflow, while exhibiting a reduced biomass growth and a minimal flux towards violacein synthesis. Finally, interestingly, the addition of the violacein precursor (tryptophan) in the medium inhibited high producer but enhanced low producer's productivity, leading to hypotheses of unknown pathway regulations (such as metabolite channeling).« less

  12. An integrated model of cardiac mitochondrial energy metabolism and calcium dynamics.

    PubMed

    Cortassa, Sonia; Aon, Miguel A; Marbán, Eduardo; Winslow, Raimond L; O'Rourke, Brian

    2003-04-01

    We present an integrated thermokinetic model describing control of cardiac mitochondrial bioenergetics. The model describes the tricarboxylic acid (TCA) cycle, oxidative phosphorylation, and mitochondrial Ca(2+) handling. The kinetic component of the model includes effectors of the TCA cycle enzymes regulating production of NADH and FADH(2), which in turn are used by the electron transport chain to establish a proton motive force (Delta mu(H)), driving the F(1)F(0)-ATPase. In addition, mitochondrial matrix Ca(2+), determined by Ca(2+) uniporter and Na(+)/Ca(2+) exchanger activities, regulates activity of the TCA cycle enzymes isocitrate dehydrogenase and alpha-ketoglutarate dehydrogenase. The model is described by twelve ordinary differential equations for the time rate of change of mitochondrial membrane potential (Delta Psi(m)), and matrix concentrations of Ca(2+), NADH, ADP, and TCA cycle intermediates. The model is used to predict the response of mitochondria to changes in substrate delivery, metabolic inhibition, the rate of adenine nucleotide exchange, and Ca(2+). The model is able to reproduce, qualitatively and semiquantitatively, experimental data concerning mitochondrial bioenergetics, Ca(2+) dynamics, and respiratory control. Significant increases in oxygen consumption (V(O(2))), proton efflux, NADH, and ATP synthesis, in response to an increase in cytoplasmic Ca(2+), are obtained when the Ca(2+)-sensitive dehydrogenases are the main rate-controlling steps of respiratory flux. These responses diminished when control is shifted downstream (e.g., the respiratory chain or adenine nucleotide translocator). The time-dependent behavior of the model, under conditions simulating an increase in workload, closely reproduces experimentally observed mitochondrial NADH dynamics in heart trabeculae subjected to changes in pacing frequency. The steady-state and time-dependent behavior of the model support the hypothesis that mitochondrial matrix Ca(2+) plays an

  13. An Integrated Model of Cardiac Mitochondrial Energy Metabolism and Calcium Dynamics

    PubMed Central

    Cortassa, Sonia; Aon, Miguel A.; Marbán, Eduardo; Winslow, Raimond L.; O'Rourke, Brian

    2003-01-01

    We present an integrated thermokinetic model describing control of cardiac mitochondrial bioenergetics. The model describes the tricarboxylic acid (TCA) cycle, oxidative phosphorylation, and mitochondrial Ca2+ handling. The kinetic component of the model includes effectors of the TCA cycle enzymes regulating production of NADH and FADH2, which in turn are used by the electron transport chain to establish a proton motive force (ΔμH), driving the F1F0-ATPase. In addition, mitochondrial matrix Ca2+, determined by Ca2+ uniporter and Na+/Ca2+ exchanger activities, regulates activity of the TCA cycle enzymes isocitrate dehydrogenase and α-ketoglutarate dehydrogenase. The model is described by twelve ordinary differential equations for the time rate of change of mitochondrial membrane potential (ΔΨm), and matrix concentrations of Ca2+, NADH, ADP, and TCA cycle intermediates. The model is used to predict the response of mitochondria to changes in substrate delivery, metabolic inhibition, the rate of adenine nucleotide exchange, and Ca2+. The model is able to reproduce, qualitatively and semiquantitatively, experimental data concerning mitochondrial bioenergetics, Ca2+ dynamics, and respiratory control. Significant increases in oxygen consumption (VO2), proton efflux, NADH, and ATP synthesis, in response to an increase in cytoplasmic Ca2+, are obtained when the Ca2+-sensitive dehydrogenases are the main rate-controlling steps of respiratory flux. These responses diminished when control is shifted downstream (e.g., the respiratory chain or adenine nucleotide translocator). The time-dependent behavior of the model, under conditions simulating an increase in workload, closely reproduces experimentally observed mitochondrial NADH dynamics in heart trabeculae subjected to changes in pacing frequency. The steady-state and time-dependent behavior of the model support the hypothesis that mitochondrial matrix Ca2+ plays an important role in matching energy supply with demand in

  14. Glutamate metabolism in HIV-1 infected macrophages: Role of HIV-1 Vpr

    PubMed Central

    Datta, Prasun K.; Deshmane, Satish; Khalili, Kamel; Merali, Salim; Gordon, John C.; Fecchio, Chiara; Barrero, Carlos A.

    2016-01-01

    ABSTRACT HIV-1 infected macrophages play a significant role in the neuropathogenesis of AIDS. HIV-1 viral protein R (Vpr) not only facilitates HIV-1 infection but also contribute to long-lived persistence in macrophages. Our previous studies using SILAC-based proteomic analysis showed that the expression of critical metabolic enzymes in the glycolytic pathway and tricarboxylic acid (TCA) cycle were altered in response to Vpr expression in macrophages. We hypothesized that Vpr-induced modulation of glycolysis and TCA cycle regulates glutamate metabolism and release in HIV-1 infected macrophages. We assessed the amount of specific metabolites induced by Vpr and HIV-1 in macrophages at the intracellular and extracellular level in a time-dependent manner utilizing multiple reaction monitoring (MRM) targeted metabolomics. In addition, stable isotope-labeled glucose and an MRM targeted metabolomics assay were used to evaluate the de novo synthesis and release of glutamate in Vpr overexpressing macrophages and HIV-1 infected macrophages, throughout the metabolic flux of glycolytic pathway and TCA cycle activation. The metabolic flux studies demonstrated an increase in glucose uptake, glutamate release and accumulation of α-ketoglutarate (α-KG) and glutamine in the extracellular milieu in Vpr expressing and HIV-1 infected macrophages. Interestingly, glutamate pools and other intracellular intermediates (glucose-6-phosphate (G6P), fructose-6-phosphate (F6P), citrate, malate, α-KG, and glutamine) showed a decreased trend except for fumarate, in contrast to the glutamine accumulation observed in the extracellular space in Vpr overexpressing macrophages. Our studies demonstrate that dysregulation of mitochondrial glutamate metabolism induced by Vpr in HIV-1 infected macrophages commonly seen, may contribute to neurodegeneration via excitotoxic mechanisms in the context of NeuroAIDS. PMID:27245560

  15. Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle: Focus on Shortwave and Longwave Radiative Fluxes

    NASA Astrophysics Data System (ADS)

    Pinker, R. T.; Ma, Y.; Nussbaumer, E. A.

    2012-04-01

    The overall goal of the MEaSUREs activity titled: "Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle" is to develop consistent, long-term Earth System Data Records (ESDRs) for the major components of the terrestrial water cycle at a climatic time scale. The shortwave (SW) and longwave (LW) radiative fluxes at the Earth's surface determine the exchange of energy between the land and the atmosphere are the focus of this presentation. During the last two decades, significant progress has been made in assessing the Earth Radiation Balance from satellite observations. Yet, satellite based estimates differ from each other and long term satellite observations at global scale are not readily available. There is a need to utilize existing records of satellite observations and to improve currently available estimates. This paper reports on improvements introduced to an existing methodology to estimate shortwave (SW) radiative fluxes within the atmospheric system, on the development of a new inference scheme for deriving LW fluxes, the implementation of the approach with the ISCCP DX observations and improved atmospheric inputs for the period of 1983-2007, evaluation against ground observations, and comparison with independent satellite methods and numerical models. The resulting ESDRs from the entire MEaSUREs Project are intended to provide a consistent basis for estimating the mean state and variability of the land surface water cycle at a spatial scale relevant to major global river basins. MEaSUREs Project "Developing Consistent Earth System Data Records for the Global Terrestrial Water Cycle" Team Members: E. F. Wood (PI)1, T. J Bohn2, J. L Bytheway3, X. Feng4, H. Gao2, P. R.Houser4 (CO-I), C. D Kummerow3 (CO-I), D. P Lettenmaier2 (CO-I), C. Li5, Y. Ma5, R. F MacCracken4, M. Pan1, R. T Pinker5 (CO-I), A. K. Sahoo1, J. Sheffield1 1. Dept of CEE, Princeton University, Princeton, NJ, USA. 2. Dept of CEE, University of Washington, Seattle

  16. Element Cycling and Energy Flux Responses in Ecosystem Simulations Conducted at the Chinese Lunar Palace-1

    NASA Astrophysics Data System (ADS)

    Dong, Chen; Fu, Yuming; Xie, Beizhen; Wang, Minjuan; Liu, Hong

    2017-01-01

    Bioregenerative life-support systems (BLSS) address interactions between organisms and their environment as an integrated system through the study of factors that regulate the pools and fluxes of materials and energy through ecological systems. As a simple model, using BLSS is very important in the investigation of element cycling and energy flux for sustainable development on Earth. A 105-day experiment with a high degree of closure was carried out in this system from February to May, 2014, with three volunteers. The results indicate that 247 g·d-1 carbon was imported into the system from stored food. Most hydrogen is circulated as water, and more than 99% H2O can be lost through leaf transpiration into the atmosphere. A total of 1.8 g·d-1 "unknown oxygen" emerged between the input and output of the plant growth module. For the urine processing module, 20.5% nitrogen was reused and 5.35 g·d-1 was put into the nutrient solution.

  17. Large-Scale 13C Flux Profiling Reveals Conservation of the Entner-Doudoroff Pathway as a Glycolytic Strategy among Marine Bacteria That Use Glucose

    PubMed Central

    Klingner, Arne; Bartsch, Annekathrin; Dogs, Marco; Wagner-Döbler, Irene; Jahn, Dieter; Simon, Meinhard; Brinkhoff, Thorsten; Becker, Judith

    2015-01-01

    Marine bacteria form one of the largest living surfaces on Earth, and their metabolic activity is of fundamental importance for global nutrient cycling. Here, we explored the largely unknown intracellular pathways in 25 microbes representing different classes of marine bacteria that use glucose: Alphaproteobacteria, Gammaproteobacteria, and Flavobacteriia of the Bacteriodetes phylum. We used 13C isotope experiments to infer metabolic fluxes through their carbon core pathways. Notably, 90% of all strains studied use the Entner-Doudoroff (ED) pathway for glucose catabolism, whereas only 10% rely on the Embden-Meyerhof-Parnas (EMP) pathway. This result differed dramatically from the terrestrial model strains studied, which preferentially used the EMP pathway yielding high levels of ATP. Strains using the ED pathway exhibited a more robust resistance against the oxidative stress typically found in this environment. An important feature contributing to the preferential use of the ED pathway in the oceans could therefore be enhanced supply of NADPH through this pathway. The marine bacteria studied did not specifically rely on a distinct anaplerotic route, but the carboxylation of phosphoenolpyruvate (PEP) or pyruvate for fueling of the tricarboxylic acid (TCA) cycle was evenly distributed. The marine isolates studied belong to clades that dominate the uptake of glucose, a major carbon source for bacteria in seawater. Therefore, the ED pathway may play a significant role in the cycling of mono- and polysaccharides by bacterial communities in marine ecosystems. PMID:25616803

  18. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    PubMed Central

    Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-01-01

    Abstract Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25. PMID:28781930

  19. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution.

    PubMed

    Lockwood, Mike; Owens, Mathew J; Imber, Suzanne M; James, Matthew K; Bunce, Emma J; Yeoman, Timothy K

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.

  20. Is There a CME Rate Floor? CME and Magnetic Flux Values for the Last Four Solar Cycle Minima

    NASA Astrophysics Data System (ADS)

    Webb, D. F.; Howard, R. A.; St. Cyr, O. C.; Vourlidas, A.

    2017-12-01

    The recent prolonged activity minimum has led to the question of whether there is a base level of the solar magnetic field evolution that yields a “floor” in activity levels and also in the solar wind magnetic field strength. Recently, a flux transport model coupled with magneto-frictional simulations has been used to simulate the continuous magnetic field evolution in the global solar corona for over 15 years, from 1996 to 2012. Flux rope eruptions in the simulations are estimated (Yeates), and the results are in remarkable agreement with the shape of the SOlar Heliospheric Observatory/Large Angle and Spectrometric Coronagraph Experiment coronal mass ejection (CME) rate distribution. The eruption rates at the two recent minima approximate the observed-corrected CME rates, supporting the idea of a base level of solar magnetic activity. In this paper, we address this issue by comparing annual averages of the CME occurrence rates during the last four solar cycle minima with several tracers of the global solar magnetic field. We conclude that CME activity never ceases during a cycle, but maintains a base level of 1 CME every 1.5 to ∼3 days during minima. We discuss the sources of these CMEs.

  1. Nitrous oxide flux following tropical land clearing

    NASA Technical Reports Server (NTRS)

    Luizao, Flavio; Luizao, Regina; Matson, Pamela; Livingston, Gerald; Vitousek, Peter

    1989-01-01

    The importance of seasonal cycles of N2O flux from tropical ecosystems and the possibility that tropical deforestation could contribute to the ongoing global increase in N2O concentrations were assessed by measuring N2O flux from forest, cleared land, and pasture over an annual cycle in the central Amazon. A pasture that had been converted from tropical forest had threefold greater annual N2O flux than a paired forest site; similar results were obtained in spot measurements in other pastures. If these results are general, such tropical pastures represent a globally significant source of increased N2O.

  2. Nitrous oxide flux following tropical land clearing

    NASA Astrophysics Data System (ADS)

    LuizãO, FláVio; Matson, Pamela; Livingston, Gerald; LuizãO, Regina; Vitousek, Peter

    1989-09-01

    The importance of seasonal cycles of N2O flux from tropical ecosystems and the possibility that tropical deforestation could contribute to the ongoing global increase in N2O concentrations were assessed by measuring N2O flux from forest, cleared land, and pasture over an annual cycle in the central Amazon. A pasture that had been converted from tropical forest had threefold greater annual N2O flux than a paired forest site; similar results were obtained in spot measurements in other pastures. If these results are general, such tropical pastures represent a globally significant source of increased N2O.

  3. Cellular metabolic energy modulation by tangeretin in 7,12-dimethylbenz(a) anthracene-induced breast cancer.

    PubMed

    Periyasamy, Kuppusamy; Sivabalan, Venkatachalam; Baskaran, Kuppusamy; Kasthuri, Kannayiram; Sakthisekaran, Dhanapal

    2016-03-01

    Breast cancer is the leading cause of death among women worldwide. Chemoprevention and chemotherapy play beneficial roles in reducing the incidence and mortality of cancer. Epidemiological and experimental studies showed that naturally-occurring antioxidants present in the diet may act as anticancer agents. Identifying the abnormalities of cellular energy metabolism facilitates early detection and management of breast cancer. The present study evaluated the effect of tangeretin on cellular metabolic energy fluxes in 7,12-dimethylbenz(a) anthracene (DMBA)-induced proliferative breast cancer. The results showed that the activities of glycolytic enzymes significantly increased in mammary tissues of DMBA-induced breast cancer bearing rats. The gluconeogenic tricarboxylic acid (TCA) cycle and respiratory chain enzyme activities significantly decreased in breast cancer-bearing rats. In addition, proliferating cell nuclear antigen (PCNA) was highly expressed in breast cancer tissues. However, the activities of glycolytic enzymes were significantly normalized in the tangeretin pre- and post-treated rats and the TCA cycle and respiratory chain enzyme activities were significantly increased in tangeretin treated rats. Furthermore, tangeretin down-regulated PCNA expression on breast cancer-bearing rats. Our study demonstrates that tangeretin specifically regulates cellular metabolic energy fluxes in DMBA-induced breast cancer-bearing rats. © 2016 by the Journal of Biomedical Research. All rights reserved.

  4. Analyzing Clonal Variation of Monoclonal Antibody-Producing CHO Cell Lines Using an In Silico Metabolomic Platform

    PubMed Central

    Ghorbaniaghdam, Atefeh; Chen, Jingkui; Henry, Olivier; Jolicoeur, Mario

    2014-01-01

    Monoclonal antibody producing Chinese hamster ovary (CHO) cells have been shown to undergo metabolic changes when engineered to produce high titers of recombinant proteins. In this work, we have studied the distinct metabolism of CHO cell clones harboring an efficient inducible expression system, based on the cumate gene switch, and displaying different expression levels, high and low productivities, compared to that of the parental cells from which they were derived. A kinetic model for CHO cell metabolism was further developed to include metabolic regulation. Model calibration was performed using intracellular and extracellular metabolite profiles obtained from shake flask batch cultures. Model simulations of intracellular fluxes and ratios known as biomarkers revealed significant changes correlated with clonal variation but not to the recombinant protein expression level. Metabolic flux distribution mostly differs in the reactions involving pyruvate metabolism, with an increased net flux of pyruvate into the tricarboxylic acid (TCA) cycle in the high-producer clone, either being induced or non-induced with cumate. More specifically, CHO cell metabolism in this clone was characterized by an efficient utilization of glucose and a high pyruvate dehydrogenase flux. Moreover, the high-producer clone shows a high rate of anaplerosis from pyruvate to oxaloacetate, through pyruvate carboxylase and from glutamate to α-ketoglutarate, through glutamate dehydrogenase, and a reduced rate of cataplerosis from malate to pyruvate, through malic enzyme. Indeed, the increase of flux through pyruvate carboxylase was not driven by an increased anabolic demand. It is in fact linked to an increase of the TCA cycle global flux, which allows better regulation of higher redox and more efficient metabolic states. To the best of our knowledge, this is the first time a dynamic in silico platform is proposed to analyze and compare the metabolomic behavior of different CHO clones. PMID

  5. Metabolite recycling and bidirectional C fluxes: Revolutionizing our view on microbial C cycling in soils

    NASA Astrophysics Data System (ADS)

    Dippold, M. A.; Apostel, C.; Kuzyakov, Y.

    2016-12-01

    Biogeochemists' view on microbial C transformation in soil has rarely exceed a strongly simplified concept assuming that C gets either oxidized to CO2 via the microbial catabolism or incorporated into biomass via the anabolism. However, life in a C limited environment as challenging as soil requires microbial adaptation strategies at all levels of metabolism. By coupling of position-specific labeling of core metabolites with compound-specific isotope analysis we demonstrated that catabolic oxidation of these metabolites exists in parallel to reductive, energy consuming pathways, reducing them for anabolic purposes. Up to 55% of glucose, incorporated into the glucose derivative glucosamine, first passed glycolysis before allocated back via gluconeogenesis. Similarly, glutamate-derived C is allocated via anaplerotic pathways towards fatty acid synthesis and in parallel to its oxidation in the citric acid cycle. Furthermore, position-specific labeling of rather `cost-intensive' biomass compounds such as fatty acids revealed that intact recycling of metabolites is a crucial microbial adaptation to C scarcity in soils. Both processes are unlikely to occur in pure cultures, where constant growth conditions under high C supply allow a straight unidirectional regulation of C metabolism. However, unstable environmental conditions, C scarcity and interactions between a still unknown diversity of microorganisms in soils are likely to induce the observed metabolic diversity. To understand how microorganisms catalyze the biogeochemical fluxes in soil, a profound understanding of their metabolic adaptation strategies such as recycling or switching between bidirectional fluxes is crucial. Metabolic flux models adapted to soil microbial communities and their regulatory strategies will not only deepen our understanding on the microorganims' reactions to environmental changes but also create the prerequisits for a quantitative prediction of biogeochemical fluxes based on the

  6. The photospheric magnetic flux budget

    NASA Technical Reports Server (NTRS)

    Schrijver, C. J.; Harvey, K. L.

    1994-01-01

    The ensemble of bipolar regions and the magnetic network both contain a substantial and strongly variable part of the photospheric magnetic flux at any phase in the solar cycle. The time-dependent distribution of the magnetic flux over and within these components reflects the action of the dynamo operating in the solar interior. We perform a quantitative comparison of the flux emerging in the ensemble of magnetic bipoles with the observed flux content of the solar photosphere. We discuss the photospheric flux budget in terms of flux appearance and disappearance, and argue that a nonlinear dependence exists between the flux present in the photosphere and the rate of flux appearance and disappearance. In this context, we discuss the problem of making quantitative statements about dynamos in cool stars other than the Sun.

  7. TLNS3D/CDISC Multipoint Design of the TCA Concept

    NASA Technical Reports Server (NTRS)

    Campbell, Richard L.; Mann, Michael J.

    1999-01-01

    This paper presents the work done to date by the authors on developing an efficient approach to multipoint design and applying it to the design of the HSR TCA (High Speed Research Technology Concept Aircraft) configuration. While the title indicates that this exploratory study has been performed using the TLNS3DMB flow solver and the CDISC (Constrained Direct Iterative Surface Curvature) design method, the CDISC method could have been used with any flow solver, and the multipoint design approach does not require the use of CDISC. The goal of the study was to develop a multipoint design method that could achieve a design in about the same time as 10 analysis runs.

  8. Understanding alternative fluxes/effluxes through comparative metabolic pathway analysis of phylum actinobacteria using a simplified approach.

    PubMed

    Verma, Mansi; Lal, Devi; Saxena, Anjali; Anand, Shailly; Kaur, Jasvinder; Kaur, Jaspreet; Lal, Rup

    2013-12-01

    Actinobacteria are known for their diverse metabolism and physiology. Some are dreadful human pathogens whereas some constitute the natural flora for human gut. Therefore, the understanding of metabolic pathways is a key feature for targeting the pathogenic bacteria without disturbing the symbiotic ones. A big challenge faced today is multiple drug resistance by Mycobacterium and other pathogens that utilize alternative fluxes/effluxes. With the availability of genome sequence, it is now feasible to conduct the comparative in silico analysis. Here we present a simplified approach to compare metabolic pathways so that the species specific enzyme may be traced and engineered for future therapeutics. The analyses of four key carbohydrate metabolic pathways, i.e., glycolysis, pyruvate metabolism, tri carboxylic acid cycle and pentose phosphate pathway suggest the presence of alternative fluxes. It was found that the upper pathway of glycolysis was highly variable in the actinobacterial genomes whereas lower glycolytic pathway was highly conserved. Likewise, pentose phosphate pathway was well conserved in contradiction to TCA cycle, which was found to be incomplete in majority of actinobacteria. The clustering based on presence and absence of genes of these metabolic pathways clearly revealed that members of different genera shared identical pathways and, therefore, provided an easy method to identify the metabolic similarities/differences between pathogenic and symbiotic organisms. The analyses could identify isoenzymes and some key enzymes that were found to be missing in some pathogenic actinobacteria. The present work defines a simple approach to explore the effluxes in four metabolic pathways within the phylum actinobacteria. The analysis clearly reflects that actinobacteria exhibit diverse routes for metabolizing substrates. The pathway comparison can help in finding the enzymes that can be used as drug targets for pathogens without effecting symbiotic organisms

  9. Methicillin-Susceptible Teicoplanin-Resistant Staphylococcus haemolyticus Isolate from a Bloodstream Infection with Novel Mutations in the tcaRAB Teicoplanin Resistance Operon.

    PubMed

    Bakthavatchalam, Yamuna Devi; Sudarsanam, Thambu David; Babu, Priyanka; Munuswamy, Elakkiya; Muthuirulandi Sethuvel, Dhiviya Prabaa; Devanga Ragupathi, Naveen Kumar; Veeraraghavan, Balaji

    2017-07-24

    Staphylococcus haemolyticus is a coagulase-negative staphylococcus that is frequently isolated from blood cultures. Here, we report a case of methicillin-susceptible S. haemolyticus that is resistant to teicoplanin (TEC) and heteroresistant to vancomycin (VAN). The isolate was susceptible to cefoxitin and resistant to TEC by Etest. Population analysis profile-area under the curve analysis confirmed the presence of a VAN heteroresistant subpopulation. Next-generation sequencing analysis of the genome revealed the presence of blaZ and msr(A), which encode cross-resistance to macrolide, lincosamide, and streptogramin B, and the quinolone resistance-conferring gene norA. In addition, several amino acid substitutions were observed in the TEC resistance operon tcaRAB, including I3N, I390N, and L450I in tcaA and L44V, G52V, and S87P in tcaR, as well as in the transpeptidase encoding gene walK (D336Y, R375L, and V404A) and L315 and P316 in graS. We hypothesized that this combination of mutations could confer TEC resistance and reduced VAN susceptibility.

  10. Biosynthesis of Taxadiene in Saccharomyces cerevisiae : Selection of Geranylgeranyl Diphosphate Synthase Directed by a Computer-Aided Docking Strategy

    PubMed Central

    Li, Lin-feng; Zhai, Fang; Shang, Lu-qing; Yin, Zheng; Yuan, Ying-jin

    2014-01-01

    Identification of efficient key enzymes in biosynthesis pathway and optimization of the fitness between functional modules and chassis are important for improving the production of target compounds. In this study, the taxadiene biosynthesis pathway was firstly constructed in yeast by transforming ts gene and overexpressing erg20 and thmgr. Then, the catalytic capabilities of six different geranylgeranyl diphosphate synthases (GGPPS), the key enzyme in mevalonic acid (MVA) pathway catalyzing famesyl diphosphate (FPP) to geranylgeranyl diphosphate (GGPP), were predicted using enzyme-substrate docking strategy. GGPPSs from Taxus baccata x Taxus cuspidate (GGPPSbc), Erwinia herbicola (GGPPSeh), and S. cerevisiae (GGPPSsc) which ranked 1st, 4th and 6th in docking with FPP were selected for construction. The experimental results were consistent with the computer prediction that the engineered yeast with GGPPSbc exhibited the highest production. In addition, two chassis YSG50 and W303-1A were chosen, and the titer of taxadiene reached 72.8 mg/L in chassis YSG50 with GGPPSbc. Metabolomic study revealed that the contents of tricarboxylic acid cycle (TCA) intermediates and their precursor amino acids in chassis YSG50 was lower than those in W303-1A, indicating less carbon flux was divided into TCA cycle. Furthermore, the levels of TCA intermediates in the taxadiene producing yeasts were lower than those in chassis YSG50. Thus, it may result in more carbon flux in MVA pathway in chassis YSG50, which suggested that YSG50 was more suitable for engineering the taxadiene producing yeast. These results indicated that computer-aided protein modeling directed isoenzyme selection strategy and metabolomic study could guide the rational design of terpenes biosynthetic cells. PMID:25295588

  11. Impact of a regional drought on terrestrial carbon fluxes and atmospheric carbon: results from a coupled carbon cycle model

    NASA Astrophysics Data System (ADS)

    Lee, E.; Koster, R. D.; Ott, L. E.; Weir, B.; Mahanama, S. P. P.; Chang, Y.; Zeng, F.

    2017-12-01

    Understanding the underlying processes that control the carbon cycle is key to predicting future global change. Much of the uncertainty in the magnitude and variability of the atmospheric carbon dioxide (CO2) stems from uncertainty in terrestrial carbon fluxes. Budget-based analyses show that such fluxes exhibit substantial interannual variability, but the relative impacts of temperature and moisture variations on regional and global scales are poorly understood. Here we investigate the impact of a regional drought on terrestrial carbon fluxes and CO2 mixing ratios over North America using the NASA Goddard Earth Observing System (GEOS) Model. Two 48-member ensembles of NASA GEOS-5 simulations with fully coupled land and atmosphere carbon components are performed - a control ensemble and an ensemble with an artificially imposed dry land surface anomaly for three months (April-June) over the lower Mississippi River Valley. Comparison of the results using the ensemble approach allows a direct quantification of the impact of the regional drought on local and proximate carbon exchange at the land surface via the carbon-water feedback processes.

  12. Central metabolism controls transcription of a virulence gene regulator in Vibrio cholerae

    PubMed Central

    Minato, Yusuke; Fassio, Sara R.; Wolfe, Alan J.

    2013-01-01

    ToxT is the central regulatory protein involved in activation of the main virulence genes in Vibrio cholerae. We have identified transposon insertions in central metabolism genes, whose disruption increases toxT transcription. These disrupted genes encode the primary respiration-linked sodium pump (NADH : ubiquinone oxidoreductase or NQR) and certain tricarboxylic acid (TCA) cycle enzymes. Observations made following stimulation of respiration in the nqr mutant or chemical inhibition of NQR activity in the TCA cycle mutants led to the hypothesis that NQR affects toxT transcription via the TCA cycle. That toxT transcription increased when the growth medium was supplemented with citrate, but decreased with oxaloacetate, focused our attention on the TCA cycle substrate acetyl-CoA and its non-TCA cycle metabolism. Indeed, both the nqr and the TCA cycle mutants increased acetate excretion. A similar correlation between acetate excretion and toxT transcription was observed in a tolC mutant and upon amino acid (NRES) supplementation. As acetate and its tendency to decrease pH exerted no strong effect on toxT transcription, and because disruption of the major acetate excretion pathway increased toxT transcription, we propose that toxT transcription is regulated by either acetyl-CoA or some close derivative. PMID:23429745

  13. The Role of TCA Cycle Anaplerosis in Ketosis and Fatty Liver in Periparturient Dairy Cows

    PubMed Central

    White, Heather M.

    2015-01-01

    The transition to lactation period in dairy cattle is characterized by metabolic challenges, negative energy balance, and adipose tissue mobilization. Metabolism of mobilized adipose tissue is part of the adaptive response to negative energy balance in dairy cattle; however, the capacity of the liver to completely oxidize nonesterified fatty acids may be limited and is reflective of oxaloacetate pool, the carbon carrier of the tricarboxylic acid cycle. Alternative metabolic fates of acetyl-CoA from nonesterified fatty acids include esterification to triacylglycerides and ketogenesis, and when excessive, these pathways lead to fatty liver and ketosis. Examination of the anaplerotic and cataplerotic pull of oxaloacetate by the tricarboxylic acid cycle and gluconeogenesis may provide insight into the balance of oxidation and esterification of acetyl-CoA within the liver of periparturient dairy cows. PMID:26479386

  14. The Role of TCA Cycle Anaplerosis in Ketosis and Fatty Liver in Periparturient Dairy Cows.

    PubMed

    White, Heather M

    2015-08-18

    The transition to lactation period in dairy cattle is characterized by metabolic challenges, negative energy balance, and adipose tissue mobilization. Metabolism of mobilized adipose tissue is part of the adaptive response to negative energy balance in dairy cattle; however, the capacity of the liver to completely oxidize nonesterified fatty acids may be limited and is reflective of oxaloacetate pool, the carbon carrier of the tricarboxylic acid cycle. Alternative metabolic fates of acetyl-CoA from nonesterified fatty acids include esterification to triacylglycerides and ketogenesis, and when excessive, these pathways lead to fatty liver and ketosis. Examination of the anaplerotic and cataplerotic pull of oxaloacetate by the tricarboxylic acid cycle and gluconeogenesis may provide insight into the balance of oxidation and esterification of acetyl-CoA within the liver of periparturient dairy cows.

  15. Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Ichii, K.; Hirata, R.; Takagi, K.; Asanuma, J.; Machimura, T.; Nakai, Y.; Ohta, T.; Saigusa, N.; Takahashi, Y.; Hirano, T.

    2010-03-01

    Larch forests are widely distributed across many cool-temperate and boreal regions, and they are expected to play an important role in global carbon and water cycles. Model parameterizations for larch forests still contain large uncertainties owing to a lack of validation. In this study, a process-based terrestrial biosphere model, BIOME-BGC, was tested for larch forests at six AsiaFlux sites and used to identify important environmental factors that affect the carbon and water cycles at both temporal and spatial scales. The model simulation performed with the default deciduous conifer parameters produced results that had large differences from the observed net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (RE), and evapotranspiration (ET). Therefore, we adjusted several model parameters in order to reproduce the observed rates of carbon and water cycle processes. This model calibration, performed using the AsiaFlux data, substantially improved the model performance. The simulated annual GPP, RE, NEE, and ET from the calibrated model were highly consistent with observed values. The observed and simulated GPP and RE across the six sites were positively correlated with the annual mean air temperature and annual total precipitation. On the other hand, the simulated carbon budget was partly explained by the stand disturbance history in addition to the climate. The sensitivity study indicated that spring warming enhanced the carbon sink, whereas summer warming decreased it across the larch forests. The summer radiation was the most important factor that controlled the carbon fluxes in the temperate site, but the VPD and water conditions were the limiting factors in the boreal sites. One model parameter, the allocation ratio of carbon between belowground and aboveground, was site-specific, and it was negatively correlated with the annual climate of annual mean air temperature and total precipitation. Although this study substantially

  16. Simulating carbon and water cycles of larch forests in East Asia by the BIOME-BGC model with AsiaFlux data

    NASA Astrophysics Data System (ADS)

    Ueyama, M.; Ichii, K.; Hirata, R.; Takagi, K.; Asanuma, J.; Machimura, T.; Nakai, Y.; Ohta, T.; Saigusa, N.; Takahashi, Y.; Hirano, T.

    2009-08-01

    Larch forests are widely distributed across many cool-temperate and boreal regions, and they are expected to play an important role in global carbon and water cycles. Model parameterizations for larch forests still contain large uncertainties owing to a lack of validation. In this study, a process-based terrestrial biosphere model, BIOME-BGC, was tested for larch forests at six AsiaFlux sites and used to identify important environmental factors that affect the carbon and water cycles at both temporal and spatial scales. The model simulation performed with the default deciduous conifer parameters produced results that had large differences from the observed net ecosystem exchange (NEE), gross primary productivity (GPP), ecosystem respiration (RE), and evapotranspiration (ET). Therefore, we adjusted several model parameters in order to reproduce the observed rates of carbon and water cycle processes. This model calibration, performed using the AsiaFlux data, significantly improved the model performance. The simulated annual GPP, RE, NEE, and ET from the calibrated model were highly consistent with observed values. The observed and simulated GPP and RE across the six sites are positively correlated with the annual mean air temperature and annual total precipitation. On the other hand, the simulated carbon budget is partly explained by the stand disturbance history in addition to the climate. The sensitivity study indicates that spring warming enhances the carbon sink, whereas summer warming decreases it across the larch forests. The summer radiation is the most important factor that controls the carbon fluxes in the temperate site, but the VPD and water conditions are the limiting factors in the boreal sites. One model parameter, the allocation ratio of carbon between aboveground and belowground, is site-specific, and it is negatively correlated with the annual climate of annual mean air temperature and total precipitation. Although this study significantly improves

  17. Coronal and heliospheric magnetic flux circulation and its relation to open solar flux evolution

    NASA Astrophysics Data System (ADS)

    Lockwood, Mike; Owens, Mathew J.; Imber, Suzanne M.; James, Matthew K.; Bunce, Emma J.; Yeoman, Timothy K.

    2017-06-01

    Solar cycle 24 is notable for three features that can be found in previous cycles but which have been unusually prominent: (1) sunspot activity was considerably greater in the northern/southern hemisphere during the rising/declining phase; (2) accumulation of open solar flux (OSF) during the rising phase was modest, but rapid in the early declining phase; (3) the heliospheric current sheet (HCS) tilt showed large fluctuations. We show that these features had a major influence on the progression of the cycle. All flux emergence causes a rise then a fall in OSF, but only OSF with foot points in opposing hemispheres progresses the solar cycle via the evolution of the polar fields. Emergence in one hemisphere, or symmetric emergence without some form of foot point exchange across the heliographic equator, causes poleward migrating fields of both polarities in one or both (respectively) hemispheres which temporarily enhance OSF but do not advance the polar field cycle. The heliospheric field observed near Mercury and Earth reflects the asymmetries in emergence. Using magnetograms, we find evidence that the poleward magnetic flux transport (of both polarities) is modulated by the HCS tilt, revealing an effect on OSF loss rate. The declining phase rise in OSF was caused by strong emergence in the southern hemisphere with an anomalously low HCS tilt. This implies the recent fall in the southern polar field will be sustained and that the peak OSF has limited implications for the polar field at the next sunspot minimum and hence for the amplitude of cycle 25.Plain Language SummaryThere is growing interest in being able to predict the evolution in solar conditions on a better basis than past experience, which is necessarily limited. Two of the key features of the solar magnetic <span class="hlt">cycle</span> are that the polar fields reverse just after the peak of each sunspot <span class="hlt">cycle</span> and that the polar field that has accumulated by the time of each sunspot</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.H13K..01R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.H13K..01R"><span>The NEWS Water <span class="hlt">Cycle</span> Climatology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rodell, M.; Beaudoing, H. K.; L'Ecuyer, T.; Olson, W. S.</p> <p>2012-12-01</p> <p>NASA's Energy and Water <span class="hlt">Cycle</span> Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy <span class="hlt">cycle</span> consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy <span class="hlt">Cycle</span> Climatology project was to develop "state of the global water <span class="hlt">cycle</span>" and "state of the global energy <span class="hlt">cycle</span>" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water <span class="hlt">cycle</span> component of the first phase of the project, which include seasonal (monthly) climatologies of water <span class="hlt">fluxes</span> over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the <span class="hlt">flux</span> estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized <span class="hlt">flux</span> estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120015016','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120015016"><span>The NEWS Water <span class="hlt">Cycle</span> Climatology</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rodell, Matthew; Beaudoing, Hiroko Kato; L'Ecuyer, Tristan; William, Olson</p> <p>2012-01-01</p> <p>NASA's Energy and Water <span class="hlt">Cycle</span> Study (NEWS) program fosters collaborative research towards improved quantification and prediction of water and energy <span class="hlt">cycle</span> consequences of climate change. In order to measure change, it is first necessary to describe current conditions. The goal of the first phase of the NEWS Water and Energy <span class="hlt">Cycle</span> Climatology project was to develop "state of the global water <span class="hlt">cycle</span>" and "state of the global energy <span class="hlt">cycle</span>" assessments based on data from modern ground and space based observing systems and data integrating models. The project was a multi-institutional collaboration with more than 20 active contributors. This presentation will describe the results of the water <span class="hlt">cycle</span> component of the first phase of the project, which include seasonal (monthly) climatologies of water <span class="hlt">fluxes</span> over land, ocean, and atmosphere at continental and ocean basin scales. The requirement of closure of the water budget (i.e., mass conservation) at various scales was exploited to constrain the <span class="hlt">flux</span> estimates via an optimization approach that will also be described. Further, error assessments were included with the input datasets, and we examine these in relation to inferred uncertainty in the optimized <span class="hlt">flux</span> estimates in order to gauge our current ability to close the water budget within an expected uncertainty range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1914560B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1914560B"><span>Nitrogen <span class="hlt">fluxes</span> in the forests of the Congo Basin</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bauters, Marijn; Verbeeck, Hans; Cizungu, Landry; Makelele, Isaac; Boeckx, Pascal</p> <p>2017-04-01</p> <p>The tropical forest of the Congo basin remains very poorly investigated and understood; mainly because of logistic, political and research capacity constraints. Nevertheless, characterization and monitoring of fundamental processes in this biome is vital to understand future responses and to correctly parameterize Earth system models. Nutrient <span class="hlt">fluxes</span> are key in these processes for the functioning of tropical forests, since CO2 uptake by terrestrial ecosystems strongly depends on site fertility, i.e. nutrient availability. Accurate projections of future net forest growth and terrestrial CO2 uptake thus necessitate an improved understanding on nutrient <span class="hlt">cycles</span> and how these are coupled to the carbon (C) <span class="hlt">cycle</span> in forests. Research in the Congo Basin region should combine assessments of both carbon <span class="hlt">fluxes</span> and the underlying nutrient <span class="hlt">cycles</span> which directly impact the forest productivity. We set up a monitoring network for nitrogen <span class="hlt">fluxes</span> in four different forest types in the Congo Basin, resulting in a unique and integrate dataset. The questions to be answered: How do the N-budgets of four different forest types in the Congo Basin compare? How do these <span class="hlt">fluxes</span> compare to <span class="hlt">fluxes</span> in the Amazon forest? What is the influence from the strong slash-and-burn regimes on the N-<span class="hlt">cycle</span> in the natural forests? We answer these questions with our empirical dataset of one hydrological year, combined with satellite and modeling data.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3271W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3271W"><span>The inconvenient truth about eddy covariance <span class="hlt">flux</span> partitioning and implications for global carbon <span class="hlt">cycle</span> estimates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wohlfahrt, Georg; Galvagno, Marta</p> <p>2016-04-01</p> <p>Ecosystem respiration (ER) and gross primary productivity (GPP) are key carbon <span class="hlt">cycle</span> concepts. Global estimates of ER and GPP are largely based on measurements of the net ecosystem CO2 exchange by means of the eddy covariance method from which ER and GPP are inferred using so-called <span class="hlt">flux</span> partitioning algorithms. Using a simple two-source model of ecosystem respiration, consisting of an above-ground respiration source driven by simulated air temperature and a below-ground respiration source driven by simulated soil temperature, we demonstrate that the two most popular <span class="hlt">flux</span> partitioning algorithms are unable to provide unbiased estimates of daytime ER (ignoring any reduction of leaf mitochondrial respiration) and thus GPP. The bias is demonstrated to be either positive or negative and to depend in a complex fashion on the driving temperature, the ratio of above- to below-ground respiration, the respective temperature sensitivities, the soil depth where the below-ground respiration source originates from (and thus phase and amplitude of soil vs. surface temperature) and day length. The insights from the modeling analysis are subject to a reality check using direct measurements of ER at a grassland where measurements of ER were conducted both during night and day using automated opaque chambers. Consistent with the modeling analysis we find that using air temperature to extrapolate from nighttime to daytime conditions overestimates daytime ER (by 20% or ca. 65 gC m-2 over a 100 day study period), while soil temperature results in an underestimation (by 4% or 12 gC m-2). We conclude with practical recommendations for eddy covariance <span class="hlt">flux</span> partitioning in the context of the FLUXNET project.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4495377','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4495377"><span>Fructose Alters Intermediary Metabolism of Glucose in Human Adipocytes and Diverts Glucose to Serine Oxidation in the One–Carbon <span class="hlt">Cycle</span> Energy Producing Pathway</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Varma, Vijayalakshmi; Boros, László G.; Nolen, Greg T.; Chang, Ching-Wei; Wabitsch, Martin; Beger, Richard D.; Kaput, Jim</p> <p>2015-01-01</p> <p>Increased consumption of sugar and fructose as sweeteners has resulted in the utilization of fructose as an alternative metabolic fuel that may compete with glucose and alter its metabolism. To explore this, human Simpson-Golabi-Behmel Syndrome (SGBS) preadipocytes were differentiated to adipocytes in the presence of 0, 1, 2.5, 5 or 10 mM of fructose added to a medium containing 5 mM of glucose representing the normal blood glucose concentration. Targeted tracer [1,2-13C2]-d-glucose fate association approach was employed to examine the influence of fructose on the intermediary metabolism of glucose. Increasing concentrations of fructose robustly increased the oxidation of [1,2-13C2]-d-glucose to 13CO2 (p < 0.000001). However, glucose-derived 13CO2 negatively correlated with 13C labeled glutamate, 13C palmitate, and M+1 labeled lactate. These are strong markers of limited tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span>, fatty acid synthesis, pentose <span class="hlt">cycle</span> <span class="hlt">fluxes</span>, substrate turnover and NAD+/NADP+ or ATP production from glucose via complete oxidation, indicating diminished mitochondrial energy metabolism. Contrarily, a positive correlation was observed between glucose-derived 13CO2 formed and 13C oleate and doses of fructose which indicate the elongation and desaturation of palmitate to oleate for storage. Collectively, these results suggest that fructose preferentially drives glucose through serine oxidation glycine cleavage (SOGC pathway) one-carbon <span class="hlt">cycle</span> for NAD+/NADP+ production that is utilized in fructose-induced lipogenesis and storage in adipocytes. PMID:26087138</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMEP53E..04S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMEP53E..04S"><span>Numerical Modeling of River <span class="hlt">Fluxes</span> Under Changing Environmental Conditions (Invited)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Simpson, G.</p> <p>2013-12-01</p> <p>High frequency climate <span class="hlt">cycles</span> have a major impact on landscapes, but it remains uncertain if alluvial rivers can transfer the resulting sediment pulses downstream to sedimentary basins. Stratigraphic records located near the mouth of rivers exhibit cyclicity consistent with orbital forcing. However, in some cases, the sediment supply from rivers appears to have remained remarkably constant despite changes in climate, which has been interpreted to indicate that rivers dampen rapid variability. Here, we employ a physically-based numerical model to resolve this outstanding problem. Our simulations show that rivers forced with water <span class="hlt">flux</span> <span class="hlt">cycles</span> exhibit highly pulsed sediment outflux records, even when the period of forcing is several orders of magnitude shorter than river response times. This non-linear amplified system response characterised by positive feedback is related to the strong negative correlation between water <span class="hlt">flux</span> and the equilibrium slope of a river. We also show that the apparent stability of sediment <span class="hlt">fluxes</span> based on time-averaged data is an artifact of integrating highly episodic records over multiple <span class="hlt">cycles</span> rather than a signature of diffusive floodplain processes. We conclude that marine sedimentary basins may record sediment-<span class="hlt">flux</span> <span class="hlt">cycles</span> resulting from discharge (and ultimately climate) variability, whereas they may be relatively insensitive to pure sediment-<span class="hlt">flux</span> perturbations (such as for example those induced by tectonics).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS54B..01D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS54B..01D"><span>Carbon <span class="hlt">Cycle</span> in South China Sea: <span class="hlt">Flux</span>, Controls and Global Implications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dai, M.; Cao, Z.; Yang, W.; Guo, X.; Yin, Z.; Gan, J.</p> <p>2016-12-01</p> <p>The contemporary coastal ocean is generally seen as a significant CO2 sink of 0.2-0.4 Pg C/yr at the global scale. However, mechanistic understanding of the coastal ocean carbon <span class="hlt">cycle</span> remains limited, leading to the unanswered question of why some coastal systems are sources while others are sinks of atmospheric CO2. As the largest marginal sea of Northern Pacific, the South China Sea (SCS) is a mini-ocean with wide shelves in both its southern and northern parts. Its northern shelf, which receives significant land inputs from the Pearl River, a world major river, can be categorized as a River-Dominated Margin (RioMar) during peak discharges, and is characterized as a CO2 sink to the atmosphere. The SCS basin is identified as an Ocean-Dominated Margin (OceMar) and a CO2 source. OceMar is characterized by exchange with the open ocean via a two-dimensional (at least) process, i.e., the horizontal intrusion of open ocean water and subsequent vertical mixing and upwelling. Depending on the different ratios of dissolved inorganic carbon (DIC) and nutrients from the source waters into the continental margins, the relative consumption or removal bwtween DIC and nutrients, when being transported into the euphotic zones where biogeochemical processes take over, determines the CO2 <span class="hlt">fluxes</span>. Thus, excess DIC relative to nutrients existing in the upper layer will lead to CO2 degassing. The CO2 <span class="hlt">fluxes</span> in both RioMars and OceMars can be quantified using a semi-analytical diagnostic approach by coupling the physical dynamics and biogeochemical processes. We extended our mechanistic studies in the SCS to other OceMars including the Caribbean Sea, the Arabian Sea, and the upwelling system off the Oregon-California coast, and RioMars including the East China Sea and Amazon River plume to demonstrate the global implications of our SCS carbon studies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B13B0183R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B13B0183R"><span>Response of Soil Biogeochemistry to Freeze-thaw <span class="hlt">Cycles</span>: Impacts on Greenhouse Gas Emission and Nutrient <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rezanezhad, F.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.</p> <p>2014-12-01</p> <p>Freeze-thaw is an abiotic stress applied to soils and is a natural process at medium to high latitudes. Freezing and thawing processes influence not only the physical properties of soil, but also the metabolic activity of soil microorganisms. Fungi and bacteria play a crucial role in soil organic matter degradation and the production of greenhouse gases (GHG) such as CO2, CH4 and N2O. Production and consumption of these atmospheric trace gases are the result of biological processes such as photosynthesis, aerobic respiration (CO2), methanogenesis, methanotrophy (CH4), nitrification and denitrification (N2O). To enhance our understanding of the effects of freeze-thaw <span class="hlt">cycles</span> on soil biogeochemical transformations and <span class="hlt">fluxes</span>, a highly instrumented soil column experiment was designed to realistically simulate freeze-thaw dynamics under controlled conditions. Pore waters collected periodically from different depths of the column and solid-phase analyses on core material obtained at the initial and end of the experiment highlighted striking geochemical <span class="hlt">cycling</span>. CO2, CH4 and N2O production at different depths within the column were quantified from dissolved gas concentrations in pore water. Subsequent emissions from the soil surface were determined by direct measurement in the head space. Pulsed CO2 emission to the headspace was observed at the onset of thawing, however, the magnitude of the pulse decreased with each subsequent freeze-thaw <span class="hlt">cycle</span> indicating depletion of a "freeze-thaw accessible" carbon pool. Pulsed CO2 emission was due to a combination of physical release of gases dissolved in porewater and entrapped below the frozen zone and changing microbial respiration in response to electron acceptor variability (O2, NO3-, SO42-). In this presentation, we focus on soil-specific physical, chemical, microbial factors (e.g. redox conditions, respiration, fermentation) and the mechanisms that drive GHG emission and nutrient <span class="hlt">cycling</span> in soils under freeze-thaw <span class="hlt">cycles</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AAS...22041101L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AAS...22041101L"><span>Are Polar Field Magnetic <span class="hlt">Flux</span> Concentrations Responsible for Missing Interplanetary <span class="hlt">Flux</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Linker, Jon A.; Downs, C.; Mikic, Z.; Riley, P.; Henney, C. J.; Arge, C. N.</p> <p>2012-05-01</p> <p>Magnetohydrodynamic (MHD) simulations are now routinely used to produce models of the solar corona and inner heliosphere for specific time periods. These models typically use magnetic maps of the photospheric magnetic field built up over a solar rotation, available from a number of ground-based and space-based solar observatories. The line-of-sight field at the Sun's poles is poorly observed, and the polar fields in these maps are filled with a variety of interpolation/extrapolation techniques. These models have been found to frequently underestimate the interplanetary magnetic <span class="hlt">flux</span> (Riley et al., 2012, in press, Stevens et al., 2012, in press) near the minimum part of the <span class="hlt">cycle</span> unless mitigating correction factors are applied. Hinode SOT observations indicate that strong concentrations of magnetic <span class="hlt">flux</span> may be present at the poles (Tsuneta et al. 2008). The ADAPT <span class="hlt">flux</span> evolution model (Arge et al. 2010) also predicts the appearance of such concentrations. In this paper, we explore the possibility that these <span class="hlt">flux</span> concentrations may account for a significant amount of magnetic <span class="hlt">flux</span> and alleviate discrepancies in interplanetary magnetic <span class="hlt">flux</span> predictions. Research supported by AFOSR, NASA, and NSF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..1511209H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..1511209H"><span>Seasonal <span class="hlt">cycle</span> of oceanic mixed layer and upper-ocean heat <span class="hlt">fluxes</span> in the Mediterranean Sea from in-situ observations.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Houpert, Loïc; Testor, Pierre; Durrieu de Madron, Xavier; Estournel, Claude; D'Ortenzio, Fabrizio</p> <p>2013-04-01</p> <p>Heat <span class="hlt">fluxes</span> across the ocean-atmosphere interface play a crucial role in the upper turbulent mixing. The depth reached by this turbulent mixing is indicated by an homogenization of seawater properties in the surface layer, and is defined as the Mixed Layer Depth (MLD). The thickness of the mixed layer determines also the heat content of the layer that directly interacts with the atmosphere. The seasonal variability of these air-sea <span class="hlt">fluxes</span> is crucial in the calculation of heat budget. An improvement in the estimate of these <span class="hlt">fluxes</span> is needed for a better understanding of the Mediterranean ocean circulation and climate, in particular in Regional Climate Models. There are few estimations of surface heat <span class="hlt">fluxes</span> based on oceanic observations in the Mediterranean, and none of them are based on mixed layer observations. So, we proposed here new estimations of these upper-ocean heat <span class="hlt">fluxes</span> based on mixed layer. We present high resolution Mediterranean climatology (0.5°) of the mean MLD based on a comprehensive collection of temperature profiles of last 43 years (1969-2012). The database includes more than 150,000 profiles, merging CTD, XBT, ARGO Profiling floats, and gliders observations. This dataset is first used to describe the seasonal <span class="hlt">cycle</span> of the mixed layer depth on the whole Mediterranean on a monthly climatological basis. Our analysis discriminates several regions with coherent behaviors, in particular the deep water formation sites, characterized by significant differences in the winter mixing intensity. Heat storage rates (HSR) were calculated as the time rate of change of the heat content integrated from the surface down to a specific depth that is defined as the MLD plus an integration constant. Monthly climatology of net heat <span class="hlt">flux</span> (NHF) from ERA-Interim reanalysis was balanced by the 1°x1° resolution heat storage rate climatology. Local heat budget balance and seasonal variability in the horizontal heat <span class="hlt">flux</span> are then discussed by taking into account</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3682967','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3682967"><span>Metabolic Analysis of Adaptation to Short-Term Changes in Culture Conditions of the Marine Diatom Thalassiosira pseudonana</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Bromke, Mariusz A.; Giavalisco, Patrick; Willmitzer, Lothar; Hesse, Holger</p> <p>2013-01-01</p> <p>This report describes the metabolic and lipidomic profiling of 97 low-molecular weight compounds from the primary metabolism and 124 lipid compounds of the diatom Thalassiosira pseudonana. The metabolic profiles were created for diatoms perturbed for 24 hours with four different treatments: (I) removal of nitrogen, (II) lower iron concentration, (III) addition of sea salt, (IV) addition of carbonate to their growth media. Our results show that as early as 24 hours after nitrogen depletion significant qualitative and quantitative change in lipid composition as well as in the primary metabolism of Thalassiosira pseudonana occurs. So we can observe the accumulation of several storage lipids, namely triacylglycerides, and <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates, of which citric acid increases more than 10-fold. These changes are positively correlated with expression of <span class="hlt">TCA</span> enzymes genes. Next to the <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates and storage lipid changes, we have observed decrease in N-containing lipids and primary metabolites such as amino acids. As a measure of counteracting nitrogen starvation, we have observed elevated expression levels of nitrogen uptake and amino acid biosynthetic genes. This indicates that diatoms can fast and efficiently adapt to changing environment by altering the metabolic <span class="hlt">fluxes</span> and metabolite abundances. Especially, the accumulation of proline and the decrease of dimethylsulfoniopropionate suggest that the proline is the main osmoprotectant for the diatom in nitrogen rich conditions. PMID:23799147</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15.2851P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15.2851P"><span>The seasonal <span class="hlt">cycle</span> of pCO2 and CO2 <span class="hlt">fluxes</span> in the Southern Ocean: diagnosing anomalies in CMIP5 Earth system models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Precious Mongwe, N.; Vichi, Marcello; Monteiro, Pedro M. S.</p> <p>2018-05-01</p> <p>The Southern Ocean forms an important component of the Earth system as a major sink of CO2 and heat. Recent studies based on the Coupled Model Intercomparison Project version 5 (CMIP5) Earth system models (ESMs) show that CMIP5 models disagree on the phasing of the seasonal <span class="hlt">cycle</span> of the CO2 <span class="hlt">flux</span> (FCO2) and compare poorly with available observation products for the Southern Ocean. Because the seasonal <span class="hlt">cycle</span> is the dominant mode of CO2 variability in the Southern Ocean, its simulation is a rigorous test for models and their long-term projections. Here we examine the competing roles of temperature and dissolved inorganic carbon (DIC) as drivers of the seasonal <span class="hlt">cycle</span> of pCO2 in the Southern Ocean to explain the mechanistic basis for the seasonal biases in CMIP5 models. We find that despite significant differences in the spatial characteristics of the mean annual <span class="hlt">fluxes</span>, the intra-model homogeneity in the seasonal <span class="hlt">cycle</span> of FCO2 is greater than observational products. FCO2 biases in CMIP5 models can be grouped into two main categories, i.e., group-SST and group-DIC. Group-SST models show an exaggeration of the seasonal rates of change of sea surface temperature (SST) in autumn and spring during the cooling and warming peaks. These higher-than-observed rates of change of SST tip the control of the seasonal <span class="hlt">cycle</span> of pCO2 and FCO2 towards SST and result in a divergence between the observed and modeled seasonal <span class="hlt">cycles</span>, particularly in the Sub-Antarctic Zone. While almost all analyzed models (9 out of 10) show these SST-driven biases, 3 out of 10 (namely NorESM1-ME, HadGEM-ES and MPI-ESM, collectively the group-DIC models) compensate for the solubility bias because of their overly exaggerated primary production, such that biologically driven DIC changes mainly regulate the seasonal <span class="hlt">cycle</span> of FCO2.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B31B1981G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B31B1981G"><span>Impacts of disturbance history on annual carbon stocks and <span class="hlt">fluxes</span> in southeastern US forests during 1986-2010 using remote sensing, forest inventory data, and a carbon <span class="hlt">cycle</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, H.; Zhou, Y.; Williams, C. A.</p> <p>2017-12-01</p> <p>Accurate assessment of forest carbon storage and uptake is central to policymaking aimed at mitigating climate change and understanding the role forests play in the global carbon <span class="hlt">cycle</span>. Disturbance events are highly heterogeneous in space and time, impacting forest carbon dynamics and challenging the quantification and reporting of carbon stocks and <span class="hlt">fluxes</span>. This study documents annual carbon stocks and <span class="hlt">fluxes</span> from 1986 and 2010 mapped at 30-m resolution across southeastern US forests, characterizing how they respond to disturbances and ensuing regrowth. Forest inventory data (FIA) are used to parameterize a carbon <span class="hlt">cycle</span> model (CASA) to represent post-disturbance carbon trajectories of carbon pools and <span class="hlt">fluxes</span> with time following harvest, fire and bark beetle disturbances of varying severity and across forest types and site productivity settings. Time since disturbance at 30 meters is inferred from two remote-sensing data sources: disturbance year (NAFD, MTBS and ADS) and biomass (NBCD 2000) intersected with FIA-derived curves of biomass accumulation with stand age. All of these elements are combined to map carbon stocks and <span class="hlt">fluxes</span> at a 30-m resolution for the year 2010, and to march backward in time for continuous, annual reporting. Results include maps of annual carbon stocks and <span class="hlt">fluxes</span> for forests of the southeastern US, and analysis of spatio-temporal patterns of carbon sources/sinks at local and regional scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A31B0072W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A31B0072W"><span>Inverse modeling of the terrestrial carbon <span class="hlt">flux</span> in China with <span class="hlt">flux</span> covariance among inverted regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, H.; Jiang, F.; Chen, J. M.; Ju, W.; Wang, H.</p> <p>2011-12-01</p> <p>Quantitative understanding of the role of ocean and terrestrial biosphere in the global carbon <span class="hlt">cycle</span>, their response and feedback to climate change is required for the future projection of the global climate. China has the largest amount of anthropogenic CO2 emission, diverse terrestrial ecosystems and an unprecedented rate of urbanization. Thus information on spatial and temporal distributions of the terrestrial carbon <span class="hlt">flux</span> in China is of great importance in understanding the global carbon <span class="hlt">cycle</span>. We developed a nested inversion with focus in China. Based on Transcom 22 regions for the globe, we divide China and its neighboring countries into 17 regions, making 39 regions in total for the globe. A Bayesian synthesis inversion is made to estimate the terrestrial carbon <span class="hlt">flux</span> based on GlobalView CO2 data. In the inversion, GEOS-Chem is used as the transport model to develop the transport matrix. A terrestrial ecosystem model named BEPS is used to produce the prior surface <span class="hlt">flux</span> to constrain the inversion. However, the sparseness of available observation stations in Asia poses a challenge to the inversion for the 17 small regions. To obtain additional constraint on the inversion, a prior <span class="hlt">flux</span> covariance matrix is constructed using the BEPS model through analyzing the correlation in the net carbon <span class="hlt">flux</span> among regions under variable climate conditions. The use of the covariance among different regions in the inversion effectively extends the information content of CO2 observations to more regions. The carbon <span class="hlt">flux</span> over the 39 land and ocean regions are inverted for the period from 2004 to 2009. In order to investigate the impact of introducing the covariance matrix with non-zero off-diagonal values to the inversion, the inverted terrestrial carbon <span class="hlt">flux</span> over China is evaluated against China<span class="hlt">Flux</span> eddy-covariance observations after applying an upscaling methodology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930067210&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsolar%2Bintensity%2Bmeasurement','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930067210&hterms=solar+intensity+measurement&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dsolar%2Bintensity%2Bmeasurement"><span>How active was solar <span class="hlt">cycle</span> 22?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoegy, W. R.; Pesnell, W. D.; Woods, T. N.; Rottman, G. J.</p> <p>1993-01-01</p> <p>Solar EUV observations from the Langmuir probe on Pioneer Venus Orbiter suggest that at EUV wavelengths solar <span class="hlt">cycle</span> 22 was more active than solar <span class="hlt">cycle</span> 21. The Langmuir probe, acting as a photodiode, measured the integrated solar EUV <span class="hlt">flux</span> over a 13 1/2 year period from January 1979 to June 1992, the longest continuous solar EUV measurement. The Ipe EUV <span class="hlt">flux</span> correlated very well with the SME measurement of L-alpha during the lifetime of SME and with the UARS SOLSTICE L-alpha from October 1991 to June 1992 when the Ipe measurement ceased. Starting with the peak of solar <span class="hlt">cycle</span> 21, there was good general agreement of Ipe EUV with the 10.7 cm, Ca K, and He 10830 solar indices, until the onset of solar <span class="hlt">cycle</span> 22. From 1989 to the start of 1992, the 10.7 cm <span class="hlt">flux</span> exhibited a broad maximum consisting of two peaks of nearly equal magnitude, whereas Ipe EUV exhibited a strong increase during this time period making the second peak significantly higher than the first. The only solar index that exhibits the same increase in solar activity as Ipe EUV and L-alpha during the <span class="hlt">cycle</span> 22 peak is the total magnetic <span class="hlt">flux</span>. The case for high activity during this peak is also supported by the presence of very high solar flare intensity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B44D..08D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B44D..08D"><span>Advancing approaches for multi-year high-frequency monitoring of temporal and spatial variability in carbon <span class="hlt">cycle</span> <span class="hlt">fluxes</span> and drivers in freshwater lakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Desai, A. R.; Reed, D. E.; Dugan, H. A.; Loken, L. C.; Schramm, P.; Golub, M.; Huerd, H.; Baldocchi, A. K.; Roberts, R.; Taebel, Z.; Hart, J.; Hanson, P. C.; Stanley, E. H.; Cartwright, E.</p> <p>2017-12-01</p> <p>Freshwater ecosystems are hotspots of regional to global carbon <span class="hlt">cycling</span>. However, significant sample biases limit our ability to quantify and predict these <span class="hlt">fluxes</span>. For lakes, scaled <span class="hlt">flux</span> estimates suffer biased sampling toward 1) low-nutrient pristine lakes, 2) infrequent temporal sampling, 3) field campaigns limited to the growing season, and 4) replicates limited to near the center of the lake. While these biases partly reflect the realities of ecological sampling, there is a need to extend observations towards the large fraction of freshwater systems worldwide that are impaired by human activities and those facing significant interannual variability owing to climatic change. Also, for seasonally ice-covered lakes, much of the annual budget of carbon <span class="hlt">fluxes</span> is thought to be explained by variation in the shoulder seasons of spring ice melt and fall turnover. Recent advances in automated, continuous multi-year temporal sampling coupled with rapid methods for spatial mapping of CO2 <span class="hlt">fluxes</span> has strong potential to rectify these sampling biases. Here, we demonstrate these advances in an eutrophic seasonally-ice covered lake with an urban shoreline and agricultural watershed. Multiple years of half-hourly eddy covariance <span class="hlt">flux</span> tower observations from two locations are coupled with frequent spatial samples of these <span class="hlt">fluxes</span> and drivers by speedboat, floating chamber <span class="hlt">fluxes</span>, automated buoy-based monitoring of lake nutrient and physical profiles, and ensemble of physical-ecosystem models. High primary productivity in the water column leads to an average net carbon sink during the growing season in much of the lake, but annual net carbon <span class="hlt">fluxes</span> show the lake can act as an annual source or a sink of carbon depending the timing of spring and fall turnover. Trophic interactions and internal waves drive shorter-term variation while nutrients and biology drive seasonal variation. However, discrepancies remain among methods to quantify <span class="hlt">fluxes</span>, requiring further investigation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29310435','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29310435"><span>Exploring the Underlying Mechanisms of the Xenopus laevis Embryonic Cell <span class="hlt">Cycle</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Kun; Wang, Jin</p> <p>2018-05-31</p> <p>The cell <span class="hlt">cycle</span> is an indispensable process in proliferation and development. Despite significant efforts, global quantification and physical understanding are still challenging. In this study, we explored the mechanisms of the Xenopus laevis embryonic cell <span class="hlt">cycle</span> by quantifying the underlying landscape and <span class="hlt">flux</span>. We uncovered the Mexican hat landscape of the Xenopus laevis embryonic cell <span class="hlt">cycle</span> with several local basins and barriers on the oscillation path. The local basins characterize the different phases of the Xenopus laevis embryonic cell <span class="hlt">cycle</span>, and the local barriers represent the checkpoints. The checkpoint mechanism of the cell <span class="hlt">cycle</span> is revealed by the landscape basins and barriers. While landscape shape determines the stabilities of the states on the oscillation path, the curl <span class="hlt">flux</span> force determines the stability of the cell <span class="hlt">cycle</span> flow. Replication is fundamental for biology of living cells. We quantify the input energy (through the entropy production) as the thermodynamic requirement for initiation and sustainability of single cell life (cell <span class="hlt">cycle</span>). Furthermore, we also quantify curl <span class="hlt">flux</span> originated from the input energy as the dynamical requirement for the emergence of a new stable phase (cell <span class="hlt">cycle</span>). This can provide a new quantitative insight for the origin of single cell life. In fact, the curl <span class="hlt">flux</span> originated from the energy input or nutrition supply determines the speed and guarantees the progression of the cell <span class="hlt">cycle</span>. The speed of the cell <span class="hlt">cycle</span> is a hallmark of cancer. We characterized the quality of the cell <span class="hlt">cycle</span> by the coherence time and found it is supported by the <span class="hlt">flux</span> and energy cost. We are also able to quantify the degree of time irreversibility by the cross correlation function forward and backward in time from the stochastic traces in the simulation or experiments, providing a way for the quantification of the time irreversibility and the <span class="hlt">flux</span>. Through global sensitivity analysis upon landscape and <span class="hlt">flux</span>, we can identify the key elements for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19990056481&hterms=Magnetic+Flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2BFlux','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19990056481&hterms=Magnetic+Flux&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2BFlux"><span>Magnetic <span class="hlt">flux</span> in modeled magnetic clouds at 1 AU and some specific comparisons to associated photospheric <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lepping, R. P.; Szabo, A.; DeForest, C. E.; Thompson, B. J.</p> <p>1997-01-01</p> <p>In order to better understand the solar origins of magnetic clouds, statistical distributions of the estimated axial magnetic <span class="hlt">flux</span> of 30 magnetic clouds at 1 AU, separated according to their occurrence during the solar <span class="hlt">cycle</span>, were obtained and a comparison was made of the magnetic <span class="hlt">flux</span> of a magnetic cloud to the aggregate <span class="hlt">flux</span> of apparently associated photospheric magnetic <span class="hlt">flux</span> tubes, for some specific cases. The 30 magnetic clouds comprise 12 cases from WIND, and the remainder from IMP-8, earlier IMPs, the International Sun-Earth Explorer (ISEE) 3 and HELIOS. The total magnetic <span class="hlt">flux</span> along the cloud axis was estimated using a constant alpha, cylindrical, force-free <span class="hlt">flux</span> rope model to determine cloud diameter and axial magentic field strength. The distribution of magentic <span class="hlt">fluxes</span> for the 30 clouds is shown to be in the form of a skewed Gaussian.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRA..12212274S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRA..12212274S"><span><span class="hlt">Flux</span> Enhancements of > 30 keV Electrons at Low Drift Shells L < 1.2 During Last Solar <span class="hlt">Cycles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Suvorova, A. V.</p> <p>2017-12-01</p> <p>We present results of statistical analysis of enhancements of >30 keV electrons observed by the NOAA/POES satellites during solar <span class="hlt">cycles</span> 23 and 24 (1998-2016) at low drift shells L < 1.2, so-called forbidden zone. We collected 1,750 days ( 25% of the total time) when <span class="hlt">fluxes</span> of the forbidden energetic electrons (FEE) exceeded 103 (cm2 s sr)-1. We found 530 days, when FEE <span class="hlt">fluxes</span> reached high intensity from 104 up to 107 (cm2 s sr)-1. It was found that the FEE enhancements were observed mostly often at the declining phases and solar minimum. More than 85% of the events occurred under fast solar wind (V > 450 km/s), high substorm activity (AL >150 nT), and enhanced interplanetary electric field perturbations (VδB > 1.5 mV/m). The FEE occurrence rate peaks around the local midnight. We have also found a quite unexpected annual variation of the FEE occurrence rate with a pronounced maximum from May to September, a minor peak in December-January, and minima at the equinoxes. The May-September peak, persisting at different solar <span class="hlt">cycle</span> phases, was assumed to originate from high conductivity in the auroral ionosphere, which is controlled by the dipole tilt angle and provides better conditions for penetration of electric field perturbations into the inner magnetosphere. This allows explanation of the shape and amplitude of annual variation in the FEE occurrence rate from the convolution of the solar wind driver with the penetration conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29494607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29494607"><span>Predicting the accumulation of storage compounds by Rhodococcus jostii RHA1 in the feast-famine growth <span class="hlt">cycles</span> using genome-scale <span class="hlt">flux</span> balance analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tajparast, Mohammad; Frigon, Dominic</p> <p>2018-01-01</p> <p>Feast-famine <span class="hlt">cycles</span> in biological wastewater resource recovery systems select for bacterial species that accumulate intracellular storage compounds such as poly-β-hydroxybutyrate (PHB), glycogen, and triacylglycerols (TAG). These species survive better the famine phase and resume rapid substrate uptake at the beginning of the feast phase faster than microorganisms unable to accumulate storage. However, ecophysiological conditions favouring the accumulation of either storage compounds remain to be clarified, and predictive capabilities need to be developed to eventually rationally design reactors producing these compounds. Using a genome-scale metabolic modelling approach, the storage metabolism of Rhodococcus jostii RHA1 was investigated for steady-state feast-famine <span class="hlt">cycles</span> on glucose and acetate as the sole carbon sources. R. jostii RHA1 is capable of accumulating the three storage compounds (PHB, TAG, and glycogen) simultaneously. According to the experimental observations, when glucose was the substrate, feast phase chemical oxygen demand (COD) accumulation was similar for the three storage compounds; when acetate was the substrate, however, PHB accumulation was 3 times higher than TAG accumulation and essentially no glycogen was accumulated. These results were simulated using the genome-scale metabolic model of R. jostii RHA1 (iMT1174) by means of <span class="hlt">flux</span> balance analysis (FBA) to determine the objective functions capable of predicting these behaviours. Maximization of the growth rate was set as the main objective function, while minimization of total reaction <span class="hlt">fluxes</span> and minimization of metabolic adjustment (environmental MOMA) were considered as the sub-objective functions. The environmental MOMA sub-objective performed better than the minimization of total reaction <span class="hlt">fluxes</span> sub-objective function at predicting the mixture of storage compounds accumulated. Additional experiments with 13C-labelled bicarbonate (HCO3-) found that the <span class="hlt">fluxes</span> through the central</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5832212','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5832212"><span>Predicting the accumulation of storage compounds by Rhodococcus jostii RHA1 in the feast-famine growth <span class="hlt">cycles</span> using genome-scale <span class="hlt">flux</span> balance analysis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tajparast, Mohammad</p> <p>2018-01-01</p> <p>Feast-famine <span class="hlt">cycles</span> in biological wastewater resource recovery systems select for bacterial species that accumulate intracellular storage compounds such as poly-β-hydroxybutyrate (PHB), glycogen, and triacylglycerols (TAG). These species survive better the famine phase and resume rapid substrate uptake at the beginning of the feast phase faster than microorganisms unable to accumulate storage. However, ecophysiological conditions favouring the accumulation of either storage compounds remain to be clarified, and predictive capabilities need to be developed to eventually rationally design reactors producing these compounds. Using a genome-scale metabolic modelling approach, the storage metabolism of Rhodococcus jostii RHA1 was investigated for steady-state feast-famine <span class="hlt">cycles</span> on glucose and acetate as the sole carbon sources. R. jostii RHA1 is capable of accumulating the three storage compounds (PHB, TAG, and glycogen) simultaneously. According to the experimental observations, when glucose was the substrate, feast phase chemical oxygen demand (COD) accumulation was similar for the three storage compounds; when acetate was the substrate, however, PHB accumulation was 3 times higher than TAG accumulation and essentially no glycogen was accumulated. These results were simulated using the genome-scale metabolic model of R. jostii RHA1 (iMT1174) by means of <span class="hlt">flux</span> balance analysis (FBA) to determine the objective functions capable of predicting these behaviours. Maximization of the growth rate was set as the main objective function, while minimization of total reaction <span class="hlt">fluxes</span> and minimization of metabolic adjustment (environmental MOMA) were considered as the sub-objective functions. The environmental MOMA sub-objective performed better than the minimization of total reaction <span class="hlt">fluxes</span> sub-objective function at predicting the mixture of storage compounds accumulated. Additional experiments with 13C-labelled bicarbonate (HCO3−) found that the <span class="hlt">fluxes</span> through the central</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3957653','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3957653"><span>Achromobacter denitrificans Strain YD35 Pyruvate Dehydrogenase Controls NADH Production To Allow Tolerance to Extremely High Nitrite Levels</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Doi, Yuki; Shimizu, Motoyuki; Fujita, Tomoya; Nakamura, Akira; Takizawa, Noboru</p> <p>2014-01-01</p> <p>We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2−) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2−-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the <span class="hlt">TCA</span> <span class="hlt">cycle</span> and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of <span class="hlt">TCA</span> <span class="hlt">cycle</span> metabolism to NO2− tolerance. A mutant in which the pdh gene cluster was disrupted (Δpdh mutant) could not grow in the presence of 100 mM NO2−. Nitrite decreased the cellular NADH/NAD+ ratio and the cellular ATP level. These defects were more severe in the Δpdh mutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2−-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the <span class="hlt">TCA</span> <span class="hlt">cycle</span>, compensated for these defects caused by disruption of the pdh gene cluster and those caused by NO2−. These findings demonstrate a link between NO2− tolerance and pyruvate/acetate metabolism through the <span class="hlt">TCA</span> <span class="hlt">cycle</span>. The <span class="hlt">TCA</span> <span class="hlt">cycle</span> mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2−-tolerating mechanism in this strain. PMID:24413603</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27868154','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27868154"><span>Alternative Fuels in Epilepsy and Amyotrophic Lateral Sclerosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tefera, Tesfaye W; Tan, Kah Ni; McDonald, Tanya S; Borges, Karin</p> <p>2017-06-01</p> <p>This review summarises the recent findings on metabolic treatments for epilepsy and Amyotrophic Lateral Sclerosis (ALS) in honour of Professor Ursula Sonnewald. The metabolic impairments in rodent models of these disorders as well as affected patients are being discussed. In both epilepsy and ALS, there are defects in glucose uptake and reduced tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycling</span>, at least in part due to reduced amounts of C4 <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates. In addition there are impairments in glycolysis in ALS. A reduction in glucose uptake can be addressed by providing the brain with alternative fuels, such as ketones or medium-chain triglycerides. As anaplerotic fuels, such as the triglyceride of heptanoate, triheptanoin, refill the <span class="hlt">TCA</span> <span class="hlt">cycle</span> C4/C5 intermediate pool that is deficient, they are ideal to boost <span class="hlt">TCA</span> <span class="hlt">cycling</span> and thus the oxidative metabolism of all fuels.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4114659','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4114659"><span>Icotinib inhibits the invasion of <span class="hlt">Tca</span>8113 cells via downregulation of nuclear factor κB-mediated matrix metalloproteinase expression</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>YANG, CAILING; YAN, JIANGUO; YUAN, GUOYAN; ZHANG, YINGHUA; LU, DERONG; REN, MINGXIN; CUI, WEIGANG</p> <p>2014-01-01</p> <p>Icotinib is an epidermal growth factor receptor tyrosine kinase inhibitor, which has been revealed to inhibit proliferation in tumor cells. However, the effect of icotinib on cancer cell metastasis remains to be explained. This study examines the effect of icotinib on the migration and invasion of squamous cells of tongue carcinoma (<span class="hlt">Tca</span>8113 cells) in vitro. The results of the Boyden chamber invasion assay demonstrated that icotinib reduced cell invasion, suppressed the protein levels of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and increased the expression of tissue inhibitor of metalloproteinase-1. In addition, icotinib was found to significantly decrease the protein levels of nuclear factor κB (NF-κB) p65, which suggested that icotinib inhibits NF-κB activity. Furthermore, treatment with the NF-κB inhibitor, pyrrolidine dithiocarbamate, suppressed cell invasion and MMP-2 expression. These results suggested that icotinib inhibits the invasion of <span class="hlt">Tca</span>8113 cells by downregulating MMP via the inactivation of the NF-κB signaling pathways. PMID:25120710</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25120710','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25120710"><span>Icotinib inhibits the invasion of <span class="hlt">Tca</span>8113 cells via downregulation of nuclear factor κB-mediated matrix metalloproteinase expression.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Cailing; Yan, Jianguo; Yuan, Guoyan; Zhang, Yinghua; Lu, Derong; Ren, Mingxin; Cui, Weigang</p> <p>2014-09-01</p> <p>Icotinib is an epidermal growth factor receptor tyrosine kinase inhibitor, which has been revealed to inhibit proliferation in tumor cells. However, the effect of icotinib on cancer cell metastasis remains to be explained. This study examines the effect of icotinib on the migration and invasion of squamous cells of tongue carcinoma (<span class="hlt">Tca</span>8113 cells) in vitro . The results of the Boyden chamber invasion assay demonstrated that icotinib reduced cell invasion, suppressed the protein levels of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, and increased the expression of tissue inhibitor of metalloproteinase-1. In addition, icotinib was found to significantly decrease the protein levels of nuclear factor κB (NF-κB) p65, which suggested that icotinib inhibits NF-κB activity. Furthermore, treatment with the NF-κB inhibitor, pyrrolidine dithiocarbamate, suppressed cell invasion and MMP-2 expression. These results suggested that icotinib inhibits the invasion of <span class="hlt">Tca</span>8113 cells by downregulating MMP via the inactivation of the NF-κB signaling pathways.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940020793','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940020793"><span>Solar magnetic <span class="hlt">cycle</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Harvey, Karen L.</p> <p>1993-01-01</p> <p>Using NSO/KP magnetograms, the pattern and rate of the emergence of magnetic <span class="hlt">flux</span> and the development of the large-scale patterns of unipolar fields are considered in terms of the solar magnetic <span class="hlt">cycle</span>. Magnetic <span class="hlt">flux</span> emerges in active regions at an average rate of 2 x 10(exp 21) Mx/day, approximately 10 times the estimated rate in ephemeral regions. Observations are presented that demonstrate that the large-scale unipolar fields originate in active regions and activity nests. For <span class="hlt">cycle</span> 21, the net contribution of ephemeral regions to the axial dipole moment of the Sun is positive, and is of opposite sign to that of active regions. Its amplitude is smaller by a factor of 6, assuming an average lifetime of ephemeral regions of 8 hours. Active regions larger than 4500 Mm(sup 2) are the primary contributor to the <span class="hlt">cycle</span> variation of Sun's axial dipole moment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654320-solar-cycle-another-moderate-cycle','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654320-solar-cycle-another-moderate-cycle"><span>SOLAR <span class="hlt">CYCLE</span> 25: ANOTHER MODERATE <span class="hlt">CYCLE</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Cameron, R. H.; Schüssler, M.; Jiang, J., E-mail: cameron@mps.mpg.de</p> <p>2016-06-01</p> <p>Surface <span class="hlt">flux</span> transport simulations for the descending phase of <span class="hlt">Cycle</span> 24 using random sources (emerging bipolar magnetic regions) with empirically determined scatter of their properties provide a prediction of the axial dipole moment during the upcoming activity minimum together with a realistic uncertainty range. The expectation value for the dipole moment around 2020 (2.5 ± 1.1 G) is comparable to that observed at the end of <span class="hlt">Cycle</span> 23 (about 2 G). The empirical correlation between the dipole moment during solar minimum and the strength of the subsequent <span class="hlt">cycle</span> thus suggests that <span class="hlt">Cycle</span> 25 will be of moderate amplitude, not muchmore » higher than that of the current <span class="hlt">cycle</span>. However, the intrinsic uncertainty of such predictions resulting from the random scatter of the source properties is considerable and fundamentally limits the reliability with which such predictions can be made before activity minimum is reached.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120016060','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120016060"><span>SIERRA-<span class="hlt">Flux</span>: Measuring Regional Surface <span class="hlt">Fluxes</span> of Carbon Dioxide, Methane, and Water Vapor from an Unmanned Aircraft System</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fladeland; Yates, Emma Louise; Bui, Thaopaul Van; Dean-Day, Jonathan; Kolyer, Richard</p> <p>2011-01-01</p> <p>The Eddy-Covariance Method for quantifying surface-atmosphere <span class="hlt">fluxes</span> is a foundational technique for measuring net ecosystem exchange and validating regional-to-global carbon <span class="hlt">cycle</span> models. While towers or ships are the most frequent platform for measuring surface-atmosphere exchange, experiments using aircraft for <span class="hlt">flux</span> measurements have yielded contributions to several large-scale studies including BOREAS, SMACEX, RECAB by providing local-to-regional coverage beyond towers. The low-altitude flight requirements make airborne <span class="hlt">flux</span> measurements particularly dangerous and well suited for unmanned aircraft.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5775R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5775R"><span>The contribution of chemical <span class="hlt">fluxes</span> across the sediment-water interface to carbon <span class="hlt">cycling</span> in estuarine regions: A case study at the Rhône River mouth (NW Mediterranean)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rassmann, Jens; Eitel, Eryn; Bombled, Bruno; Lansard, Bruno; Taillefert, Martial; Rabouille, Christophe</p> <p>2016-04-01</p> <p>Despite their small surface compared to the global oceans, continental shelf regions play a significant role in the global carbon <span class="hlt">cycle</span>. Whereas shelf regions are seen as a sink for atmospheric CO2, estuarine regions are seen as a source. These regions are caracterized by the export of allochthonous terrigenous organic matter (OM) and the production of autochthonous marine organic carbon. An important fraction of this OM is mineralized in the sediments close to the river mouth. As a result, high exchange <span class="hlt">fluxes</span> of dissolved inorganic carbon (DIC), total alkalinity (TA), oxygen and nutriments cross the sediment-water interface (SWI) and cause acidification of the bottom waters. Potentially, primary production in the water column is enhanced by these <span class="hlt">fluxes</span>. Therefore, OM mineralisation in estuarine regions plays a key role in the carbon <span class="hlt">cycle</span> as a direct producer of DIC and as a potential control factor for primary production. This work aims to quantify chemical <span class="hlt">fluxes</span> through the SWI at the prodelta of the Rhone River (Mediterranen). In September 2015, a benthic chamber has been deployed at several stations in the prodelta to measure directly (in situ) <span class="hlt">fluxes</span> of DIC, TA, ammonium and dissolved calcium at the SWI. At the same stations, in situ microprofiles of oxygen and pH have been recorded and sediment cores were taken for pore water extraction and analysis (DIC, TA, NH4+ and Ca2+). The results show a strong decrease of the <span class="hlt">fluxes</span> in offshore direction indicating a strong variation of respiration rates in this direction. From pore water profiles, diffusive <span class="hlt">fluxes</span> have been calculated and compared with the <span class="hlt">fluxes</span> measured by the benthic chamber. This comparison enables us to include pore water profiles from previous investigations to calculate a carbon mass budget of this region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27474708','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27474708"><span>Use of a Bacterial Luciferase Monitoring System To Estimate Real-Time Dynamics of Intracellular Metabolism in Escherichia coli.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shimada, Tomohiro; Tanaka, Kan</p> <p>2016-10-01</p> <p>Regulation of central carbon metabolism has long been an important research subject in every organism. While the dynamics of metabolic flows during changes in available carbon sources have been estimated based on changes in metabolism-related gene expression, as well as on changes in the metabolome, the <span class="hlt">flux</span> change itself has scarcely been measured because of technical difficulty, which has made conclusions elusive in many cases. Here, we used a monitoring system employing Vibrio fischeri luciferase to probe the intracellular metabolic condition in Escherichia coli Using a batch culture provided with a limited amount of glucose, we performed a time course analysis, where the predominant carbon source shifts from glucose to acetate, and identified a series of sequential peaks in the luciferase activity (peaks 1 to 4). Two major peaks, peaks 1 and 3, were considered to correspond to the glucose and acetate consuming phases, respectively, based on the glucose, acetate, and dissolved oxygen concentrations in the medium. The pattern of these peaks was changed by the addition of a different carbon source or by an increasing concentration of glucose, which was consistent with the present model. Genetically, mutations involved in glycolysis or the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span>/gluconeogenesis specifically affected peak 1 or peak 3, respectively, as expected from the corresponding metabolic phase. Intriguingly, mutants for the acetate excretion pathway showed a phenotype of extended peak 2 and delayed transition to the <span class="hlt">TCA</span> <span class="hlt">cycle</span>/gluconeogenesis phase, which suggests that peak 2 represents the metabolic transition phase. These results indicate that the bacterial luciferase monitoring system is useful to understand the real-time dynamics of metabolism in living bacterial cells. Intracellular metabolic flows dynamically change during shifts in available carbon sources. However, because of technical difficulty, the <span class="hlt">flux</span> change has scarcely been measured in living cells. Here</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22364305-observations-modeling-north-south-asymmetries-using-flux-transport-dynamo','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22364305-observations-modeling-north-south-asymmetries-using-flux-transport-dynamo"><span>OBSERVATIONS AND MODELING OF NORTH-SOUTH ASYMMETRIES USING A <span class="hlt">FLUX</span> TRANSPORT DYNAMO</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Shetye, Juie; Tripathi, Durgesh; Dikpati, Mausumi</p> <p>2015-02-01</p> <p>The peculiar behavior of solar <span class="hlt">cycle</span> 23 and its prolonged minima has been one of the most studied problems over the past few years. In the present paper, we study the asymmetries in active region magnetic <span class="hlt">flux</span> in the northern and southern hemispheres during the complete solar <span class="hlt">cycle</span> 23 and the rising phase of solar <span class="hlt">cycle</span> 24. During the declining phase of solar <span class="hlt">cycle</span> 23, we find that the magnetic <span class="hlt">flux</span> in the southern hemisphere is about 10 times stronger than that in the northern hemisphere; however, during the rising phase of <span class="hlt">cycle</span> 24, this trend is reversed. The magnetic fluxmore » becomes about a factor of four stronger in the northern hemisphere than in the southern hemisphere. Additionally, we find that there was a significant delay (about five months) in change of the polarity in the southern hemisphere in comparison with the northern hemisphere. These results provide us with hints of how the toroidal <span class="hlt">fluxes</span> have contributed to the solar dynamo during the prolonged minima in solar <span class="hlt">cycle</span> 23 and in the rising phase of solar <span class="hlt">cycle</span> 24. Using a solar <span class="hlt">flux</span>-transport dynamo model, we demonstrate that persistently stronger sunspot <span class="hlt">cycles</span> in one hemisphere could be caused by the effect of greater inflows into active region belts in that hemisphere. Observations indicate that greater inflows are associated with stronger activity. Some other change or difference in meridional circulation between hemispheres could cause the weaker hemisphere to become the stronger one.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1400151','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1400151"><span>Configurable Crossbar Switch for Deterministic, Low-latency Inter-blade Communications in a Micro<span class="hlt">TCA</span> Platform</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Karamooz, Saeed; Breeding, John Eric; Justice, T Alan</p> <p></p> <p>As Micro<span class="hlt">TCA</span> expands into applications beyond the telecommunications industry from which it originated, it faces new challenges in the area of inter-blade communications. The ability to achieve deterministic, low-latency communications between blades is critical to realizing a scalable architecture. In the past, legacy bus architectures accomplished inter-blade communications using dedicated parallel buses across the backplane. Because of limited fabric resources on its backplane, Micro<span class="hlt">TCA</span> uses the carrier hub (MCH) for this purpose. Unfortunately, MCH products from commercial vendors are limited to standard bus protocols such as PCI Express, Serial Rapid IO and 10/40GbE. While these protocols have exceptional throughput capability,more » they are neither deterministic nor necessarily low-latency. To overcome this limitation, an MCH has been developed based on the Xilinx Virtex-7 690T FPGA. This MCH provides the system architect/developer complete flexibility in both the interface protocol and routing of information between blades. In this paper, we present the application of this configurable MCH concept to the Machine Protection System under development for the Spallation Neutron Sources's proton accelerator. Specifically, we demonstrate the use of the configurable MCH as a 12x4-lane crossbar switch using the Aurora protocol to achieve a deterministic, low-latency data link. In this configuration, the crossbar has an aggregate bandwidth of 48 GB/s.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMGC23B0924P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMGC23B0924P"><span>Impact of climate variability on N and C <span class="hlt">flux</span> within the life <span class="hlt">cycle</span> of biofuels produced from crop residues</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pourhashem, G.; Block, P. J.; Adler, P. R.; Spatari, S.</p> <p>2013-12-01</p> <p>Biofuels from agricultural feedstocks (lignocellulose) are under development to meet national policy objectives for producing domestic renewable fuels. Using crop residues such as corn stover as feedstock for biofuel production can minimize the risks associated with food market disruption; however, it demands managing residue removal to minimize soil carbon loss, erosion, and to ensure nutrient replacement. Emissions of nitrous oxide and changes to soil organic carbon (SOC) are subject to variability in time due to local climate conditions and cultivation practices. Our objective is to investigate the effect of climate inputs (precipitation and temperature) on biogeochemical greenhouse gas (GHG) emissions (N2O and SOC expressed as CO2) within the life <span class="hlt">cycle</span> of biofuels produced from agricultural residues. Specifically, we investigate the impact of local climate variability on soil carbon and nitrogen <span class="hlt">fluxes</span> over a 20-year biorefinery lifetime where biomass residue is used for lignocellulosic ethanol production. We investigate two cases studied previously (Pourhashem et al, 2013) where the fermentable sugars in the agricultural residue are converted to ethanol (biofuel) and the lignin byproduct is used in one of two ways: 1) power co-generation; or 2) application to land as a carbon/nutrient-rich amendment to soil. In the second case SOC losses are mitigated through returning the lignin component to land while the need for fertilizer addition is also eliminated, however in both cases N2O and SOC are subject to variability due to variable climate conditions. We used the biogeochemical model DayCent to predict soil carbon and nitrogen <span class="hlt">fluxes</span> considering soil characteristics, tillage practices and local climate (e.g. temperature and rainfall). We address the impact of climate variability on the soil carbon and nitrogen <span class="hlt">fluxes</span> by implementing a statistical bootstrap resampling method based on a historic data set (1980 to 2000). The ensuing probabilistic outputs from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B53B0530M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B53B0530M"><span>Carbonic anhydrase distribution across organisms and environments: genomic predictors for soil enzymatic <span class="hlt">fluxes</span> of carbon <span class="hlt">cycle</span> tracers δ18O and COS</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meredith, L. K.; Singer, E.</p> <p>2016-12-01</p> <p>Carbonyl sulfide (COS) and the oxygen isotope composition (δ18O) of CO2 are potential tools for differentiating the contributions of photosynthesis and respiration to the balance of global carbon <span class="hlt">cycling</span>. These processes are coupled at the leaf level via the enzyme carbonic anhydrase (CA), which hydrolyzes CO2 in the first biochemical step of the photosynthetic pathway (CO2 + H2O ⇌ HCO3- + H+) and correspondingly structural analogue COS (COS + H2O → CO2 + H2S). CA also accelerates the exchange of oxygen isotopes between CO2 and H2O leading to a distinct isotopic imprint. The biogeochemical <span class="hlt">cycles</span> of these tracers include significant, yet poorly characterized soil processes that challenge their utility for probing the carbon <span class="hlt">cycle</span>. In soils, microbial CA also hydrolyze COS and accelerate O isotope exchange between CO2 and soil water. Genomic predictors of microbial CA activity may help account and predict for these soil <span class="hlt">fluxes</span>. Using a bioinformatics approach, we assess the distribution of the six known CA classes (α, β, γ, δ, η, ζ) in organisms ranging from fungi and plants to archaea and bacteria, and ask whether CA diversity is linked to soil microbial diversity. We survey the diversity and relative abundance of CA in a wide variety of environments and estimate the sensitivity of CA to biome and land use. Finally, we compare the CA distribution in soils to measurements (oxygen isotope and COS <span class="hlt">fluxes</span>) and models of CA activity to develop genomic predictors for CA activity. This work provides the first survey of CA in soils, a step towards understanding the significant role of CA in microbial ecology and microbe-mediated biogeochemical <span class="hlt">cycles</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..1611035M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..1611035M"><span>Evaluation of various Land<span class="hlt">Flux</span> evapotranspiration algorithms using the Land<span class="hlt">Flux</span>-EVAL synthesis benchmark products and observational data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Michel, Dominik; Hirschi, Martin; Jimenez, Carlos; McCabe, Mathew; Miralles, Diego; Wood, Eric; Seneviratne, Sonia</p> <p>2014-05-01</p> <p>Research on climate variations and the development of predictive capabilities largely rely on globally available reference data series of the different components of the energy and water <span class="hlt">cycles</span>. Several efforts aimed at producing large-scale and long-term reference data sets of these components, e.g. based on in situ observations and remote sensing, in order to allow for diagnostic analyses of the drivers of temporal variations in the climate system. Evapotranspiration (ET) is an essential component of the energy and water <span class="hlt">cycle</span>, which can not be monitored directly on a global scale by remote sensing techniques. In recent years, several global multi-year ET data sets have been derived from remote sensing-based estimates, observation-driven land surface model simulations or atmospheric reanalyses. The Land<span class="hlt">Flux</span>-EVAL initiative presented an ensemble-evaluation of these data sets over the time periods 1989-1995 and 1989-2005 (Mueller et al. 2013). Currently, a multi-decadal global reference heat <span class="hlt">flux</span> data set for ET at the land surface is being developed within the Land<span class="hlt">Flux</span> initiative of the Global Energy and Water <span class="hlt">Cycle</span> Experiment (GEWEX). This Land<span class="hlt">Flux</span> v0 ET data set comprises four ET algorithms forced with a common radiation and surface meteorology. In order to estimate the agreement of this Land<span class="hlt">Flux</span> v0 ET data with existing data sets, it is compared to the recently available Land<span class="hlt">Flux</span>-EVAL synthesis benchmark product. Additional evaluation of the Land<span class="hlt">Flux</span> v0 ET data set is based on a comparison to in situ observations of a weighing lysimeter from the hydrological research site Rietholzbach in Switzerland. These analyses serve as a test bed for similar evaluation procedures that are envisaged for ESA's WACMOS-ET initiative (http://wacmoset.estellus.eu). Reference: Mueller, B., Hirschi, M., Jimenez, C., Ciais, P., Dirmeyer, P. A., Dolman, A. J., Fisher, J. B., Jung, M., Ludwig, F., Maignan, F., Miralles, D. G., McCabe, M. F., Reichstein, M., Sheffield, J., Wang, K</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH41E2412B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH41E2412B"><span>Modeling of the solar <span class="hlt">cycle</span> modulated interstellar He, Ne, and O pick-up ion <span class="hlt">flux</span> along the Earth orbit</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bzowski, M.; Sokol, J. M.; Kubiak, M. A.; Moebius, E.</p> <p>2015-12-01</p> <p>Interstellar pick-up ions (PUIs) are used to study in-situ the interstellar flow through the heliosphere. The locations of the peaks of the downwind focusing cone and the upwind crescent as observed in the PUI <span class="hlt">flux</span> have been used as signatures for the flow direction of neutral interstellar (ISN) gas into the heliosphere. We study the modulation of interstellar He, Ne, and O PUI along the Earth orbit over almost the entire solar activity <span class="hlt">cycle</span> from 2002 to 2013. We present the expected density of ISN atoms and the resulting PUI <span class="hlt">fluxes</span> with their modulation due to varying ionization over the solar <span class="hlt">cycle</span>. Considering the important role of the finite injection speed of ISN atoms and of adiabatic PUI cooling, we show that Ne and O always form an upwind crescent in the PUI <span class="hlt">flux</span>, but that the crescent formation for He PUIs strongly depends on the integration boundaries for the PUI distribution. Because the crescent has been observed for all three species, we find that the classical model of PUI evolution by Vasyliunas & Siscoe (1976) may not be sufficient to reproduce the upwind structure of He PUIs. We also find that ecliptic longitude of the PUI peak in the focusing cone is a good proxy for the inflow direction of ISN He and Ne during solar minimum, but not for ISN O, which exhibits a systematic shift in the model. On the other hand, the peak location derived from the crescent may not be a good proxy to determine the inflow longitude because it is highly modulated by short-time (few months) variations in the ionization losses. These lead to a corrugated crescent structure and may shift the fitted position of the crescent peak used to determine the inflow direction by up to 10°, with the strongest effects for the species that are heavily affected by ionization, i.e., O and Ne. These findings are in a qualitative agreement with results of in-situ PUI measurements, which showed that the location of PUI maximum varies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26516924','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26516924"><span>Modeling and Simulation of Optimal Resource Management during the Diurnal <span class="hlt">Cycle</span> in Emiliania huxleyi by Genome-Scale Reconstruction and an Extended <span class="hlt">Flux</span> Balance Analysis Approach.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Knies, David; Wittmüß, Philipp; Appel, Sebastian; Sawodny, Oliver; Ederer, Michael; Feuer, Ronny</p> <p>2015-10-28</p> <p>The coccolithophorid unicellular alga Emiliania huxleyi is known to form large blooms, which have a strong effect on the marine carbon <span class="hlt">cycle</span>. As a photosynthetic organism, it is subjected to a circadian rhythm due to the changing light conditions throughout the day. For a better understanding of the metabolic processes under these periodically-changing environmental conditions, a genome-scale model based on a genome reconstruction of the E. huxleyi strain CCMP 1516 was created. It comprises 410 reactions and 363 metabolites. Biomass composition is variable based on the differentiation into functional biomass components and storage metabolites. The model is analyzed with a <span class="hlt">flux</span> balance analysis approach called diurnal <span class="hlt">flux</span> balance analysis (diuFBA) that was designed for organisms with a circadian rhythm. It allows storage metabolites to accumulate or be consumed over the diurnal <span class="hlt">cycle</span>, while keeping the structure of a classical FBA problem. A feature of this approach is that the production and consumption of storage metabolites is not defined externally via the biomass composition, but the result of optimal resource management adapted to the diurnally-changing environmental conditions. The model in combination with this approach is able to simulate the variable biomass composition during the diurnal <span class="hlt">cycle</span> in proximity to literature data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28503999','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28503999"><span>Quantitative assessment of brain glucose metabolic rates using in vivo deuterium magnetic resonance spectroscopy.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Lu, Ming; Zhu, Xiao-Hong; Zhang, Yi; Mateescu, Gheorghe; Chen, Wei</p> <p>2017-11-01</p> <p>Quantitative assessment of cerebral glucose consumption rate (CMR glc ) and tricarboxylic acid <span class="hlt">cycle</span> <span class="hlt">flux</span> (V <span class="hlt">TCA</span> ) is crucial for understanding neuroenergetics under physiopathological conditions. In this study, we report a novel in vivo Deuterium ( 2 H) MRS (DMRS) approach for simultaneously measuring and quantifying CMR glc and V <span class="hlt">TCA</span> in rat brains at 16.4 Tesla. Following a brief infusion of deuterated glucose, dynamic changes of isotope-labeled glucose, glutamate/glutamine (Glx) and water contents in the brain can be robustly monitored from their well-resolved 2 H resonances. Dynamic DMRS glucose and Glx data were employed to determine CMR glc and V <span class="hlt">TCA</span> concurrently. To test the sensitivity of this method in response to altered glucose metabolism, two brain conditions with different anesthetics were investigated. Increased CMR glc (0.46 vs. 0.28 µmol/g/min) and V <span class="hlt">TCA</span> (0.96 vs. 0.6 µmol/g/min) were found in rats under morphine as compared to deeper anesthesia using 2% isoflurane. This study demonstrates the feasibility and new utility of the in vivo DMRS approach to assess cerebral glucose metabolic rates at high/ultrahigh field. It provides an alternative MRS tool for in vivo study of metabolic coupling relationship between aerobic and anaerobic glucose metabolisms in brain under physiopathological states.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130003182','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130003182"><span>Reproducing the Photospheric Magnetic Field Evolution during the Rise of <span class="hlt">Cycle</span> 24 with <span class="hlt">Flux</span> Transport by Supergranules</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David; Upton, Lisa</p> <p>2012-01-01</p> <p>We simulate the transport of magnetic <span class="hlt">flux</span> in the Sun s photosphere by an evolving pattern of cellular horizontal flows (supergranules). Characteristics of the simulated flow pattern can match observed characteristics including the velocity power spectrum, cell lifetimes, and cell motions in longitude and latitude. Simulations using an average, and north-south symmetric, meridional motion of the cellular pattern produce polar magnetic fields that are too weak in the North and too strong in the South. Simulations using cellular patterns with meridional motions that evolve with the observed changes in strength and north-south asymmetry will be analyzed to see if they reproduce the polar field evolution observed during the rise of <span class="hlt">Cycle</span> 24.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130003202','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130003202"><span>Reproducing the Photospheric Magnetic Field Evolution During the Rise of <span class="hlt">Cycle</span> 24 with <span class="hlt">Flux</span> Transport by Supergranules</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David H.; Upton, Lisa</p> <p>2012-01-01</p> <p>We simulate the transport of magnetic <span class="hlt">flux</span> in the Sun s photosphere by an evolving pattern of cellular horizontal flows (supergranules). Characteristics of the simulated flow pattern match observed characteristics including the velocity power spectrum, cell lifetimes, and cell pattern motion in longitude and latitude. Simulations using an average, and north-south symmetric, meridional motion of the cellular pattern produce polar magnetic fields that are too weak in the North and too strong in the South. Simulations using cellular patterns with meridional motions that evolve with the observed changes in strength and north-south asymmetry will be analyzed to see if they reproduce the polar field evolution observed during the rise of <span class="hlt">Cycle</span> 24.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26358840','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26358840"><span>13C metabolic <span class="hlt">flux</span> analysis at a genome-scale.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gopalakrishnan, Saratram; Maranas, Costas D</p> <p>2015-11-01</p> <p>Metabolic models used in 13C metabolic <span class="hlt">flux</span> analysis generally include a limited number of reactions primarily from central metabolism. They typically omit degradation pathways, complete cofactor balances, and atom transition contributions for reactions outside central metabolism. This study addresses the impact on prediction fidelity of scaling-up mapping models to a genome-scale. The core mapping model employed in this study accounts for (75 reactions and 65 metabolites) primarily from central metabolism. The genome-scale metabolic mapping model (GSMM) (697 reaction and 595 metabolites) is constructed using as a basis the iAF1260 model upon eliminating reactions guaranteed not to carry <span class="hlt">flux</span> based on growth and fermentation data for a minimal glucose growth medium. Labeling data for 17 amino acid fragments obtained from cells fed with glucose labeled at the second carbon was used to obtain <span class="hlt">fluxes</span> and ranges. Metabolic <span class="hlt">fluxes</span> and confidence intervals are estimated, for both core and genome-scale mapping models, by minimizing the sum of square of differences between predicted and experimentally measured labeling patterns using the EMU decomposition algorithm. Overall, we find that both topology and estimated values of the metabolic <span class="hlt">fluxes</span> remain largely consistent between core and GSM model. Stepping up to a genome-scale mapping model leads to wider <span class="hlt">flux</span> inference ranges for 20 key reactions present in the core model. The glycolysis <span class="hlt">flux</span> range doubles due to the possibility of active gluconeogenesis, the <span class="hlt">TCA</span> <span class="hlt">flux</span> range expanded by 80% due to the availability of a bypass through arginine consistent with labeling data, and the transhydrogenase reaction <span class="hlt">flux</span> was essentially unresolved due to the presence of as many as five routes for the inter-conversion of NADPH to NADH afforded by the genome-scale model. By globally accounting for ATP demands in the GSMM model the unused ATP decreased drastically with the lower bound matching the maintenance ATP requirement. A non</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4115496','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4115496"><span>Metformin and phenformin deplete tricarboxylic acid <span class="hlt">cycle</span> and glycolytic intermediates during cell transformation and NTPs in cancer stem cells</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Janzer, Andreas; German, Natalie J.; Gonzalez-Herrera, Karina N.; Asara, John M.; Haigis, Marcia C.; Struhl, Kevin</p> <p>2014-01-01</p> <p>Metformin, a first-line diabetes drug linked to cancer prevention in retrospective clinical analyses, inhibits cellular transformation and selectively kills breast cancer stem cells (CSCs). Although a few metabolic effects of metformin and the related biguanide phenformin have been investigated in established cancer cell lines, the global metabolic impact of biguanides during the process of neoplastic transformation and in CSCs is unknown. Here, we use LC/MS/MS metabolomics (>200 metabolites) to assess metabolic changes induced by metformin and phenformin in an Src-inducible model of cellular transformation and in mammosphere-derived breast CSCs. Although phenformin is the more potent biguanide in both systems, the metabolic profiles of these drugs are remarkably similar, although not identical. During the process of cellular transformation, biguanide treatment prevents the boost in glycolytic intermediates at a specific stage of the pathway and coordinately decreases tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediates. In contrast, in breast CSCs, biguanides have a modest effect on glycolytic and <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates, but they strongly deplete nucleotide triphosphates and may impede nucleotide synthesis. These metabolic profiles are consistent with the idea that biguanides inhibit mitochondrial complex 1, but they indicate that their metabolic effects differ depending on the stage of cellular transformation. PMID:25002509</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25002509','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25002509"><span>Metformin and phenformin deplete tricarboxylic acid <span class="hlt">cycle</span> and glycolytic intermediates during cell transformation and NTPs in cancer stem cells.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Janzer, Andreas; German, Natalie J; Gonzalez-Herrera, Karina N; Asara, John M; Haigis, Marcia C; Struhl, Kevin</p> <p>2014-07-22</p> <p>Metformin, a first-line diabetes drug linked to cancer prevention in retrospective clinical analyses, inhibits cellular transformation and selectively kills breast cancer stem cells (CSCs). Although a few metabolic effects of metformin and the related biguanide phenformin have been investigated in established cancer cell lines, the global metabolic impact of biguanides during the process of neoplastic transformation and in CSCs is unknown. Here, we use LC/MS/MS metabolomics (>200 metabolites) to assess metabolic changes induced by metformin and phenformin in an Src-inducible model of cellular transformation and in mammosphere-derived breast CSCs. Although phenformin is the more potent biguanide in both systems, the metabolic profiles of these drugs are remarkably similar, although not identical. During the process of cellular transformation, biguanide treatment prevents the boost in glycolytic intermediates at a specific stage of the pathway and coordinately decreases tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediates. In contrast, in breast CSCs, biguanides have a modest effect on glycolytic and <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates, but they strongly deplete nucleotide triphosphates and may impede nucleotide synthesis. These metabolic profiles are consistent with the idea that biguanides inhibit mitochondrial complex 1, but they indicate that their metabolic effects differ depending on the stage of cellular transformation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040171823&hterms=mass+fraction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmass%2Bfraction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040171823&hterms=mass+fraction&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmass%2Bfraction"><span>Mass and Ozone <span class="hlt">Fluxes</span> from the Lowermost Stratosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schoeberl, Mark R.; Olsen, Mark A.</p> <p>2004-01-01</p> <p>Net mass <span class="hlt">flux</span> from the stratosphere to the troposphere can be computed from the heating rate along the 380K isentropic surface and the time rate of change of the mass of the lowermost stratosphere (the region between the tropopause and the 380K isentrope). Given this net mass <span class="hlt">flux</span> and the cross tropopause diabatic mass <span class="hlt">flux</span>, the residual adiabatic mass <span class="hlt">flux</span> across the tropopause can also be estimated. These <span class="hlt">fluxes</span> have been computed using meteorological fields from a free-running general circulation model (FVGCM) and two assimilation data sets, FVDAS, and UKMO. The data sets tend to agree that the annual average net mass <span class="hlt">flux</span> for the Northern Hemisphere is about 1P10 kg/s. There is less agreement on the southern Hemisphere <span class="hlt">flux</span> that might be half as large. For all three data sets, the adiabatic mass <span class="hlt">flux</span> is computed to be from the upper troposphere into the lowermost stratosphere. This <span class="hlt">flux</span> will dilute air entering from higher stratospheric altitudes. The mass <span class="hlt">fluxes</span> are convolved with ozone mixing ratios from the Goddard 3D CTM (which uses the FVGCM) to estimate the cross-tropopause transport of ozone. A relatively large adiabatic <span class="hlt">flux</span> of tropospheric ozone from the tropical upper troposphere into the extratropical lowermost stratosphere dilutes the stratospheric air in the lowermost stratosphere. Thus, a significant fraction of any measured ozone STE may not be ozone produced in the higher Stratosphere. The results also illustrate that the annual <span class="hlt">cycle</span> of ozone concentration in the lowermost stratosphere has as much of a role as the transport in the seasonal ozone <span class="hlt">flux</span> <span class="hlt">cycle</span>. This implies that a simplified calculation of ozone STE mass from air mass and a mean ozone mixing ratio may have a large uncertainty.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016NatSR...626515V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016NatSR...626515V"><span>Artificial Autopolyploidization Modifies the Tricarboxylic Acid <span class="hlt">Cycle</span> and GABA Shunt in Arabidopsis thaliana Col-0</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vergara, Fredd; Kikuchi, Jun; Breuer, Christian</p> <p>2016-05-01</p> <p>Autopolyploidy is a process whereby the chromosome set is multiplied and it is a common phenomenon in angiosperms. Autopolyploidy is thought to be an important evolutionary force that has led to the formation of new plant species. Despite its relevance, the consequences of autopolyploidy in plant metabolism are poorly understood. This study compares the metabolic profiles of natural diploids and artificial autotetraploids of Arabidopsis thaliana Col-0. Different physiological parameters are compared between diploids and autotetraploids using nuclear magnetic resonance (NMR), elemental analysis (carbon:nitrogen balance) and quantitative real-time PCR (qRT-PCR). The main difference between diploid and autotetraploid A. thaliana Col-0 is observed in the concentration of metabolites related to the tricarboxylic acid <span class="hlt">cycle</span> (<span class="hlt">TCA</span>) and γ-amino butyric acid (GABA) shunt, as shown by multivariate statistical analysis of NMR spectra. qRT-PCR shows that genes related to the <span class="hlt">TCA</span> and GABA shunt are also differentially expressed between diploids and autotetraploids following similar trends as their corresponding metabolites. Solid evidence is presented to demonstrate that autopolyploidy influences core plant metabolic processes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24164397','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24164397"><span>Differential effects of ethanol on regional glutamatergic and GABAergic neurotransmitter pathways in mouse brain.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tiwari, Vivek; Veeraiah, Pandichelvam; Subramaniam, Vaidyanathan; Patel, Anant Bahadur</p> <p>2014-03-01</p> <p>This study investigates the effects of ethanol on neuronal and astroglial metabolism using (1)H-[(13)C]-NMR spectroscopy in conjunction with infusion of [1,6-(13)C2]/[1-(13)C]glucose or [2-(13)C]acetate, respectively. A three-compartment metabolic model was fitted to the (13)C turnover of GluC3 , GluC4, GABAC 2, GABAC 3, AspC3 , and GlnC4 from [1,6-(13)C2 ]glucose to determine the rates of tricarboxylic acid (<span class="hlt">TCA</span>) and neurotransmitter <span class="hlt">cycle</span> associated with glutamatergic and GABAergic neurons. The ratio of neurotransmitter <span class="hlt">cycle</span> to <span class="hlt">TCA</span> <span class="hlt">cycle</span> <span class="hlt">fluxes</span> for glutamatergic and GABAegic neurons was obtained from the steady-state [2-(13)C]acetate experiment and used as constraints during the metabolic model fitting. (1)H MRS measurement suggests that depletion of ethanol from cerebral cortex follows zero order kinetics with rate 0.18 ± 0.04 μmol/g/min. Acute exposure of ethanol reduces the level of glutamate and aspartate in cortical region. GlnC4 labeling was found to be unchanged from a 15 min infusion of [2-(13)C]acetate suggesting that acute ethanol exposure does not affect astroglial metabolism in naive mice. Rates of <span class="hlt">TCA</span> and neurotransmitter <span class="hlt">cycle</span> associated with glutamatergic and GABAergic neurons were found to be significantly reduced in cortical and subcortical regions. Acute exposure of ethanol perturbs the level of neurometabolites and decreases the excitatory and inhibitory activity differentially across the regions of brain. Depletion of ethanol and its effect on brain functions were measured using (1)H and (1)H-[(13)C]-NMR spectroscopy in conjunction with infusion of (13)C-labeled substrates. Ethanol depletion from brain follows zero order kinetics. Ethanol perturbs level of glutamate, and the excitatory and inhibitory activity in mice brain. © 2013 International Society for Neurochemistry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16666557','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16666557"><span>Mitochondrial Respiration Can Support NO(3) and NO(2) Reduction during Photosynthesis : Interactions between Photosynthesis, Respiration, and N Assimilation in the N-Limited Green Alga Selenastrum minutum.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Weger, H G; Turpin, D H</p> <p>1989-02-01</p> <p>Mass spectrometric analysis shows that assimilation of inorganic nitrogen (NH(4) (+), NO(2) (-), NO(3) (-)) by N-limited cells of Selenastrum minutum (Naeg.) Collins results in a stimulation of tricarboxylic acid <span class="hlt">cycle</span> (<span class="hlt">TCA</span> <span class="hlt">cycle</span>) CO(2) release in both the light and dark. In a previous study we have shown that <span class="hlt">TCA</span> <span class="hlt">cycle</span> reductant generated during NH(4) (+) assimilation is oxidized via the cytochrome electron transport chain, resulting in an increase in respiratory O(2) consumption during photosynthesis (HG Weger, DG Birch, IR Elrifi, DH Turpin [1988] Plant Physiol 86: 688-692). NO(3) (-) and NO(2) (-) assimilation resulted in a larger stimulation of <span class="hlt">TCA</span> <span class="hlt">cycle</span> CO(2) release than did NH(4) (+), but a much smaller stimulation of mitochondrial O(2) consumption. NH(4) (+) assimilation was the same in the light and dark and insensitive to DCMU, but was 82% inhibited by anaerobiosis in both the light and dark. NO(3) (-) and NO(2) (-) assimilation rates were maximal in the light, but assimilation could proceed at substantial rates in the light in the presence of DCMU and in the dark. Unlike NH(4) (+), NO(3) (-) and NO(2) (-) assimilation were relatively insensitive to anaerobiosis. These results indicated that operation of the mitochondrial electron transport chain was not required to maintain <span class="hlt">TCA</span> <span class="hlt">cycle</span> activity during NO(3) (-) and NO(2) (-) assimilation, suggesting an alternative sink for <span class="hlt">TCA</span> <span class="hlt">cycle</span> generated reductant. Evaluation of changes in gross O(2) consumption during NO(3) (-) and NO(2) (-) assimilation suggest that <span class="hlt">TCA</span> <span class="hlt">cycle</span> reductant was exported to the chloroplast during photosynthesis and used to support NO(3) (-) and NO(2) (-) reduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1246159','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1246159"><span>Ameri<span class="hlt">Flux</span> US-SuS Maui Sugarcane Lee/Sheltered</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Anderson, Ray [USDA-Agricultural Research Service, United States Salinity Laboratory, Contaminant Fate and Transport Unit; Wang, Dong [USDA - Agricultural Research Service, San Joaquin Valley Agricultural Sciences Center, Water Management Research Unit</p> <p>2016-01-01</p> <p>This is the Ameri<span class="hlt">Flux</span> version of the carbon <span class="hlt">flux</span> data for the site US-SuS Maui Sugarcane Lee/Sheltered. Site Description - Continuous, irrigated, sugarcane cultivation for >100 years. Practice is to grow plant sugarcane for 2 years, drydown, burn leaves, harvest cane, and then till and replant very shortly after harvest. First <span class="hlt">cycle</span> of observations were from July 2011 to November 2012. Second <span class="hlt">cycle</span> was from April 2013 to December 2013. Site differs from Sugarcane Windy and Sugarcane Middle in soil type and meteorology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22416881-disrupted-cell-cycle-arrest-reduced-proliferation-corneal-fibroblasts-from-gcd2-patients-potential-role-altered-autophagy-flux','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22416881-disrupted-cell-cycle-arrest-reduced-proliferation-corneal-fibroblasts-from-gcd2-patients-potential-role-altered-autophagy-flux"><span>Disrupted cell <span class="hlt">cycle</span> arrest and reduced proliferation in corneal fibroblasts from GCD2 patients: A potential role for altered autophagy <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Choi, Seung-il; Dadakhujaev, Shorafidinkhuja; Maeng, Yong-Sun</p> <p></p> <p>Highlights: • Reduced cell proliferation in granular corneal dystrophy type 2. • Abnormal cell <span class="hlt">cycle</span> arrest by defective autophagy. • Decreased Cyclin A1, B1, and D1 in Atg7 gene knockout cells. • Increase in p16 and p27 expressions were observed in Atg7 gene knockout cells. - Abstract: This study investigates the role of impaired proliferation, altered cell <span class="hlt">cycle</span> arrest, and defective autophagy <span class="hlt">flux</span> of corneal fibroblasts in granular corneal dystrophy type 2 (GCD2) pathogenesis. The proliferation rates of homozygous (HO) GCD2 corneal fibroblasts at 72 h, 96 h, and 120 h were significantly lower (1.102 ± 0.027, 1.397 ± 0.039,more » and 1.527 ± 0.056, respectively) than those observed for the wild-type (WT) controls (1.441 ± 0.029, 1.758 ± 0.043, and 2.003 ± 0.046, respectively). Flow cytometry indicated a decreased G{sub 1} cell <span class="hlt">cycle</span> progression and the accumulation of cells in the S and G{sub 2}/M phases in GCD2 cells. These accumulations were associated with decreased levels of Cyclin A1, B1, and E1, and increased expression of p16 and p27. p21 and p53 expression was also significantly lower in GCD2 cells compared to the WT. Interestingly, treatment with the autophagy <span class="hlt">flux</span> inhibitor, bafilomycin A{sub 1}, resulted in similarly decreased Cyclin A1, B1, D1, and p53 expression in WT fibroblasts. Furthermore, similar findings, including a decrease in Cyclin A1, B1, and D1 and an increase in p16 and p27 expression were observed in autophagy-related 7 (Atg7; known to be essential for autophagy) gene knockout cells. These data provide new insight concerning the role of autophagy in cell <span class="hlt">cycle</span> arrest and cellular proliferation, uncovering a number of novel therapeutic possibilities for GCD2 treatment.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..349a2046W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..349a2046W"><span>Isomerization of α-pinene in the terpentin oil with <span class="hlt">TCA</span>/Natural Zeolite using microwave irradiation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wijayati, N.; Supartono; Kusumastuti, E.</p> <p>2018-04-01</p> <p>The catalytic potensial of trichloroacetic acid (<span class="hlt">TCA</span>)//Natural Zeolite in the isomerization of α-pinene in the terpentin oil was investigated. The purpose of this study is to investigate the influence of the power of microvawe on activity and selectivity of catalyst. The main product were champhene, terpinene, limonene, p-cymene, and terpinolene. The highest selectivity was 28.26% with a conversion of 23.25%, whereas the higher conversion was 98.99% with selectivity of 16.90% at room temperature using power of microwave 640 W.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70032565','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70032565"><span>Mapping carbon <span class="hlt">flux</span> uncertainty and selecting optimal locations for future <span class="hlt">flux</span> towers in the Great Plains</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Gu, Yingxin; Howard, Daniel M.; Wylie, Bruce K.; Zhang, Li</p> <p>2012-01-01</p> <p><span class="hlt">Flux</span> tower networks (e. g., Ameri<span class="hlt">Flux</span>, Agriflux) provide continuous observations of ecosystem exchanges of carbon (e. g., net ecosystem exchange), water vapor (e. g., evapotranspiration), and energy between terrestrial ecosystems and the atmosphere. The long-term time series of <span class="hlt">flux</span> tower data are essential for studying and understanding terrestrial carbon <span class="hlt">cycles</span>, ecosystem services, and climate changes. Currently, there are 13 <span class="hlt">flux</span> towers located within the Great Plains (GP). The towers are sparsely distributed and do not adequately represent the varieties of vegetation cover types, climate conditions, and geophysical and biophysical conditions in the GP. This study assessed how well the available <span class="hlt">flux</span> towers represent the environmental conditions or "ecological envelopes" across the GP and identified optimal locations for future <span class="hlt">flux</span> towers in the GP. Regression-based remote sensing and weather-driven net ecosystem production (NEP) models derived from different extrapolation ranges (10 and 50%) were used to identify areas where ecological conditions were poorly represented by the <span class="hlt">flux</span> tower sites and years previously used for mapping grassland <span class="hlt">fluxes</span>. The optimal lands suitable for future <span class="hlt">flux</span> towers within the GP were mapped. Results from this study provide information to optimize the usefulness of future <span class="hlt">flux</span> towers in the GP and serve as a proxy for the uncertainty of the NEP map.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29468113','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29468113"><span>Interaction of storage carbohydrates and other cyclic <span class="hlt">fluxes</span> with central metabolism: A quantitative approach by non-stationary 13C metabolic <span class="hlt">flux</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Suarez-Mendez, C A; Hanemaaijer, M; Ten Pierick, Angela; Wolters, J C; Heijnen, J J; Wahl, S A</p> <p>2016-12-01</p> <p>13 C labeling experiments in aerobic glucose limited cultures of Saccharomyces cerevisiae at four different growth rates (0.054; 0.101, 0.207, 0.307 h -1 ) are used for calculating <span class="hlt">fluxes</span> that include intracellular <span class="hlt">cycles</span> (e.g., storage carbohydrate <span class="hlt">cycles</span>, exchange <span class="hlt">fluxes</span> with amino acids), which are rearranged depending on the growth rate. At low growth rates the impact of the storage carbohydrate recycle is relatively more significant than at high growth rates due to a higher concentration of these materials in the cell (up to 560-fold) and higher <span class="hlt">fluxes</span> relative to the glucose uptake rate (up to 16%). Experimental observations suggest that glucose can be exported to the extracellular space, and that its source is related to storage carbohydrates, most likely via the export and subsequent extracellular breakdown of trehalose. This hypothesis is strongly supported by 13 C-labeling experimental data, measured extracellular trehalose, and the corresponding <span class="hlt">flux</span> estimations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110008573','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110008573"><span>Magnetic <span class="hlt">Flux</span> Circulation During Dawn-Dusk Oriented Interplanetary Magnetic Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mitchell, E. J.; Lopez, R. E.; Fok, M.-C.; Deng, Y.; Wiltberger, M.; Lyon, J.</p> <p>2010-01-01</p> <p>Magnetic <span class="hlt">flux</span> circulation is a primary mode of energy transfer from the solar wind into the ionosphere and inner magnetosphere. For southward interplanetary magnetic field (IMF), magnetic <span class="hlt">flux</span> circulation is described by the Dungey <span class="hlt">cycle</span> (dayside merging, night side reconnection, and magnetospheric convection), and both the ionosphere and inner magnetosphere receive energy. For dawn-dusk oriented IMF, magnetic <span class="hlt">flux</span> circulation is not well understood, and the inner magnetosphere does not receive energy. Several models have been suggested for possible reconnection patterns; the general pattern is: dayside merging; reconnection on the dayside or along the dawn/dusk regions; and, return flow on dayside only. These models are consistent with the lack of energy in the inner magnetosphere. We will present evidence that the Dungey <span class="hlt">cycle</span> does not explain the energy transfer during dawn-dusk oriented IMF. We will also present evidence of how magnetic <span class="hlt">flux</span> does circulate during dawn-dusk oriented IMF, specifically how the magnetic <span class="hlt">flux</span> reconnects and circulates back.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3682576','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3682576"><span>Role of Central Metabolism in the Osmoadaptation of the Halophilic Bacterium Chromohalobacter salexigens*</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Pastor, José M.; Bernal, Vicente; Salvador, Manuel; Argandoña, Montserrat; Vargas, Carmen; Csonka, Laszlo; Sevilla, Ángel; Iborra, José L.; Nieto, Joaquín J.; Cánovas, Manuel</p> <p>2013-01-01</p> <p>Bacterial osmoadaptation involves the cytoplasmic accumulation of compatible solutes to counteract extracellular osmolarity. The halophilic and highly halotolerant bacterium Chromohalobacter salexigens is able to grow up to 3 m NaCl in a minimal medium due to the de novo synthesis of ectoines. This is an osmoregulated pathway that burdens central metabolic routes by quantitatively drawing off <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediaries. Consequently, metabolism in C. salexigens has adapted to support this biosynthetic route. Metabolism of C. salexigens is more efficient at high salinity than at low salinity, as reflected by lower glucose consumption, lower metabolite overflow, and higher biomass yield. At low salinity, by-products (mainly gluconate, pyruvate, and acetate) accumulate extracellularly. Using [1-13C]-, [2-13C]-, [6-13C]-, and [U-13C6]glucose as carbon sources, we were able to determine the main central metabolic pathways involved in ectoines biosynthesis from glucose. C. salexigens uses the Entner-Doudoroff pathway rather than the standard glycolytic pathway for glucose catabolism, and anaplerotic activity is high to replenish the <span class="hlt">TCA</span> <span class="hlt">cycle</span> with the intermediaries withdrawn for ectoines biosynthesis. Metabolic <span class="hlt">flux</span> ratios at low and high salinity were similar, revealing a certain metabolic rigidity, probably due to its specialization to support high biosynthetic <span class="hlt">fluxes</span> and partially explaining why metabolic yields are so highly affected by salinity. This work represents an important contribution to the elucidation of specific metabolic adaptations in compatible solute-accumulating halophilic bacteria. PMID:23615905</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70022285','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70022285"><span>Dynamics of nutrient <span class="hlt">cycling</span> and related benthic nutrient and oxygen <span class="hlt">fluxes</span> during a spring phytoplankton bloom in South San Francisco Bay (USA)</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Grenz, C.; Cloern, J.E.; Hager, S.W.; Cole, B.E.</p> <p>2000-01-01</p> <p>Benthic oxygen uptake and nutrient releases of N, P and Si were measured weekly at 2 sites in South San Francisco Bay around the 1996 spring bloom. Exchanges across the sediment-water interface were estimated from whole core incubations performed in the laboratory at in situ temperature and in dark. <span class="hlt">Fluxes</span> changed significantly on a weekly time scale. Over a period of 15 wk the <span class="hlt">fluxes</span> of dissolved inorganic N, P and Si ranged from -40 to +200, 0 to 13 and from 30 to 400 ??mol m-2 h-1 respectively. Sediment oxygen demand increased from 10 before to 64 mg O2 m-2 h-1 just after the bloom period. During the bloom, nutrient <span class="hlt">fluxes</span> represented about 20, 16 and 9% of the Si, P and N requirements for primary production. Before and after the bloom period, Si <span class="hlt">fluxes</span> contributed up to 30 and > 100% of this requirement and P and N <span class="hlt">fluxes</span> up to 15 and 50% respectively. Simple empirical models explain most of the spatial-temporal variability of benthic <span class="hlt">fluxes</span> of Si, P and NH4 (but not NO3) from 3 predictor variables: sediment porosity, nutrient concentration in bottom waters and chlorophyll content of surficial sediments. These models show that algal blooms influence benthic-pelagic nutrient exchange through 2 processes: (1) depletion of nutrients from the water column (which enhances gradient-driven transports across the sediment-water interface) and (2) sedimentation of labile phytodetritus (which promotes remineralization in or on the surficial sediments). Rates and patterns of nutrient <span class="hlt">cycling</span> were very different at the shallow and deep study sites, illustrating the challenge of extrapolating measurements of coupled algae-nutrient dynamics to whole ecosystems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMGC12B..02C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMGC12B..02C"><span>Assessing and Synthesizing the Last Decade of Research on the Major Pools and <span class="hlt">Fluxes</span> of the Carbon <span class="hlt">Cycle</span> in the US and North America: An Interagency Governmental Perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cavallaro, N.; Shrestha, G.; Stover, D. B.; Zhu, Z.; Ombres, E. H.; Deangelo, B.</p> <p>2015-12-01</p> <p>The 2nd State of the Carbon <span class="hlt">Cycle</span> Report (SOCCR-2) is focused on US and North American carbon stocks and <span class="hlt">fluxes</span> in managed and unmanaged systems, including relevant carbon management science perspectives and tools for supporting and informing decisions. SOCCR-2 is inspired by the US Carbon <span class="hlt">Cycle</span> Science Plan (2011) which emphasizes global scale research on long-lived, carbon-based greenhouse gases, carbon dioxide and methane, and the major pools and <span class="hlt">fluxes</span> of the global carbon <span class="hlt">cycle</span>. Accordingly, the questions framing the Plan inform this report's topical roadmap, with a focus on US and North America in the global context: 1) How have natural processes and human actions affected the global carbon <span class="hlt">cycle</span> on land, in the atmosphere, in the oceans and in the ecosystem interfaces (e.g. coastal, wetlands, urban-rural)? 2) How have socio-economic trends affected the levels of the primary carbon-containing gases, carbon dioxide and methane, in the atmosphere? 3) How have species, ecosystems, natural resources and human systems been impacted by increasing greenhouse gas concentrations, the associated changes in climate, and by carbon management decisions and practices? To address these aspects, SOCCR-2 will encompass the following broad assessment framework: 1) Carbon <span class="hlt">Cycle</span> at Scales (Global Perspective, North American Perspective, US Perspective, Regional Perspective); 2) Role of carbon in systems (Soils; Water, Oceans, Vegetation; Terrestrial-aquatic Interfaces); 3) Interactions/Disturbance/Impacts from/on the carbon <span class="hlt">cycle</span>. 4) Carbon Management Science Perspective and Decision Support (measurements, observations and monitoring for research and policy relevant decision-support etc.). In this presentation, the Carbon <span class="hlt">Cycle</span> Interagency Working Group and the U.S. Global Change Research Program's U.S. Carbon <span class="hlt">Cycle</span> Science Program Office will highlight the scientific context, strategy, structure, team and production process of the report, which is part of the USGCRP's Sustained</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4060246','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4060246"><span>Quantitation of Cellular Metabolic <span class="hlt">Fluxes</span> of Methionine</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shlomi, Tomer; Fan, Jing; Tang, Baiqing; Kruger, Warren D.; Rabinowitz, Joshua D.</p> <p>2014-01-01</p> <p>Methionine is an essential proteogenic amino acid. In addition, it is a methyl donor for DNA and protein methylation and a propylamine donor for polyamine biosyn-thesis. Both the methyl and propylamine donation pathways involve metabolic <span class="hlt">cycles</span>, and methods are needed to quantitate these <span class="hlt">cycles</span>. Here, we describe an analytical approach for quantifying methionine metabolic <span class="hlt">fluxes</span> that accounts for the mixing of intracellular and extracellular methionine pools. We observe that such mixing prevents isotope tracing experiments from reaching the steady state due to the large size of the media pools and hence precludes the use of standard stationary metabolic <span class="hlt">flux</span> analysis. Our approach is based on feeding cells with 13C methionine and measuring the isotope-labeling kinetics of both intracellular and extracellular methionine by liquid chromatography−mass spectrometry (LC-MS). We apply this method to quantify methionine metabolism in a human fibrosarcoma cell line and study how methionine salvage pathway enzyme methylthioadenosine phosphorylase (MTAP), frequently deleted in cancer, affects methionine metabolism. We find that both transmethylation and propylamine transfer <span class="hlt">fluxes</span> amount to roughly 15% of the net methionine uptake, with no major changes due to MTAP deletion. Our method further enables the quantification of <span class="hlt">flux</span> through the pro-tumorigenic enzyme ornithine decarboxylase, and this <span class="hlt">flux</span> increases 2-fold following MTAP deletion. The analytical approach used to quantify methionine metabolic <span class="hlt">fluxes</span> is applicable for other metabolic systems affected by mixing of intracellular and extracellular metabolite pools. PMID:24397525</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3130066','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3130066"><span>Viral affects on metabolism: changes in glucose and glutamine utilization during human cytomegalovirus infection</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yu, Yongjun; Clippinger, Amy J.; Alwine, James C.</p> <p>2011-01-01</p> <p>Human cytomegalovirus (HCMV) infection causes dramatic alterations of intermediary metabolism, similar to those found in tumor cells. In infected cells, glucose carbon is not completely broken down by the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> for energy; instead it is used biosynthetically. This process requires increased glucose uptake, increased glycolysis and the diversion of glucose carbon, in the form of citrate, from the <span class="hlt">TCA</span> <span class="hlt">cycle</span> for use in HCMV-induced fatty acid biosynthesis. The diversion of citrate from the <span class="hlt">TCA</span> <span class="hlt">cycle</span> (cataplerosis) requires induction of enzymes to promote glutaminolysis, the conversion of glutamine to -ketoglutarate in order to maintain the <span class="hlt">TCA</span> <span class="hlt">cycle</span> (anaplerosis) and ATP production. Such changes could result in heretofore uncharacterized pathogenesis, potentially implicating HCMV as a subtle co-factor in many maladies, including oncogenesis. Recognition of the effects of HCMV, and other viruses, on host cell metabolism will provide new understanding of viral pathogenesis and novel avenues for antiviral therapy. PMID:21570293</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25242145','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25242145"><span>Asparagine plays a critical role in regulating cellular adaptation to glutamine depletion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Ji; Fan, Jing; Venneti, Sriram; Cross, Justin R; Takagi, Toshimitsu; Bhinder, Bhavneet; Djaballah, Hakim; Kanai, Masayuki; Cheng, Emily H; Judkins, Alexander R; Pawel, Bruce; Baggs, Julie; Cherry, Sara; Rabinowitz, Joshua D; Thompson, Craig B</p> <p>2014-10-23</p> <p>Many cancer cells consume large quantities of glutamine to maintain <span class="hlt">TCA</span> <span class="hlt">cycle</span> anaplerosis and support cell survival. It was therefore surprising when RNAi screening revealed that suppression of citrate synthase (CS), the first <span class="hlt">TCA</span> <span class="hlt">cycle</span> enzyme, prevented glutamine-withdrawal-induced apoptosis. CS suppression reduced <span class="hlt">TCA</span> <span class="hlt">cycle</span> activity and diverted oxaloacetate, the substrate of CS, into production of the nonessential amino acids aspartate and asparagine. We found that asparagine was necessary and sufficient to suppress glutamine-withdrawal-induced apoptosis without restoring the levels of other nonessential amino acids or <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates. In complete medium, tumor cells exhibiting high rates of glutamine consumption underwent rapid apoptosis when glutamine-dependent asparagine synthesis was suppressed, and expression of asparagine synthetase was statistically correlated with poor prognosis in human tumors. Coupled with the success of L-asparaginase as a therapy for childhood leukemia, the data suggest that intracellular asparagine is a critical suppressor of apoptosis in many human tumors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B41A..07P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B41A..07P"><span>Land-use change effects on <span class="hlt">fluxes</span> and isotopic composition of CO2 and CH4 in Panama, and possible insights into the atmospheric H2 <span class="hlt">cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pendall, E.; Schwendenmann, L.; Potvin, C.</p> <p>2003-12-01</p> <p>Land-use changes in tropical regions are believed to release a quantity of C to the atmosphere which is similar in magnitude to the entire "missing" sink for anthropogenic CO2. Our research attempts to evaluate carbon <span class="hlt">cycling</span> in three land-cover systems in central Panama: cow pasture, native tree plantation, and undisturbed moist forest. In this ongoing project, we are collecting samples of air from profiles in the stable, nocturnal boundary layer, which is dominated by ecosystem respiration. Samples are analyzed for CO2 and its isotopes, CH4 and its C isotopic composition, N2O, H2, CO, and SF6. We use a <span class="hlt">flux</span>-gradient method to estimate ecosystem-scale <span class="hlt">fluxes</span> of trace gases from soil to the atmosphere. Keeling plot intercepts reflect the respiratory contribution of C3 and C4 biomass under contrasting land cover systems, and how this varies with pronounced wet-dry seasonal <span class="hlt">cycles</span>. C isotopes of methane and gradients of molecular hydrogen provide insight into the source of methane production from pasture and plantation soils. Rainforest soils, in contrast, are sinks for both atmospheric methane and hydrogen. The process oriented nature of this field experiment will contribute to parameterization of carbon <span class="hlt">cycle</span> models at a variety of spatial scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920030757&hterms=refrigeration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drefrigeration','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920030757&hterms=refrigeration&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Drefrigeration"><span>Magnetic refrigeration using <span class="hlt">flux</span> compression in superconductors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Israelsson, U. E.; Strayer, D. M.; Jackson, H. W.; Petrac, D.</p> <p>1990-01-01</p> <p>The feasibility of using <span class="hlt">flux</span> compression in high-temperature superconductors to produce the large time-varying magnetic fields required in a field <span class="hlt">cycled</span> magnetic refrigerator operating between 20 K and 4 K is presently investigated. This paper describes the refrigerator concept and lists limitations and advantages in comparison with conventional refrigeration techniques. The maximum fields obtainable by <span class="hlt">flux</span> compression in high-temperature supercoductor materials, as presently prepared, are too low to serve in such a refrigerator. However, reports exist of critical current values that are near usable levels for <span class="hlt">flux</span> pumps in refrigerator applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990hmsp.conf...14L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990hmsp.conf...14L"><span>Heat <span class="hlt">flux</span> measurement in SSME turbine blade tester</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liebert, Curt H.</p> <p>1990-11-01</p> <p>Surface heat <span class="hlt">flux</span> values were measured in the turbine blade thermal <span class="hlt">cycling</span> tester located at NASA-Marshall. This is the first time heat <span class="hlt">flux</span> has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat <span class="hlt">flux</span> data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat <span class="hlt">flux</span> gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat <span class="hlt">flux</span> measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat <span class="hlt">flux</span> effects that might be observed on degraded vanes are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1990spps.conf..439L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1990spps.conf..439L"><span>Heat <span class="hlt">flux</span> measurement in SSME turbine blade tester</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liebert, Curt H.</p> <p></p> <p>Surface heat <span class="hlt">flux</span> values were measured in the turbine blade thermal <span class="hlt">cycling</span> tester located at NASA-Marshall. This is the first time heat <span class="hlt">flux</span> has been measured in a space shuttle main engine turbopump environment. Plots of transient and quasi-steady state heat <span class="hlt">flux</span> data over a range of about 0 to 15 MW/sq m are presented. Data were obtained with a miniature heat <span class="hlt">flux</span> gage device developed at NASA-Lewis. The results from these tests are being incorporated into turbine design models. Also, these gages are being considered for airfoil surface heat <span class="hlt">flux</span> measurement on turbine vanes mounted in SSME turbopump test bed engine nozzles at Marshall. Heat <span class="hlt">flux</span> effects that might be observed on degraded vanes are discussed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29736347','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29736347"><span><span class="hlt">Flux</span>Pyt: a Python-based free and open-source software for 13C-metabolic <span class="hlt">flux</span> analyses.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Desai, Trunil S; Srivastava, Shireesh</p> <p>2018-01-01</p> <p>13 C-Metabolic <span class="hlt">flux</span> analysis (MFA) is a powerful approach to estimate intracellular reaction rates which could be used in strain analysis and design. Processing and analysis of labeling data for calculation of <span class="hlt">fluxes</span> and associated statistics is an essential part of MFA. However, various software currently available for data analysis employ proprietary platforms and thus limit accessibility. We developed <span class="hlt">Flux</span>Pyt, a Python-based truly open-source software package for conducting stationary 13 C-MFA data analysis. The software is based on the efficient elementary metabolite unit framework. The standard deviations in the calculated <span class="hlt">fluxes</span> are estimated using the Monte-Carlo analysis. <span class="hlt">Flux</span>Pyt also automatically creates <span class="hlt">flux</span> maps based on a template for visualization of the MFA results. The <span class="hlt">flux</span> distributions calculated by <span class="hlt">Flux</span>Pyt for two separate models: a small tricarboxylic acid <span class="hlt">cycle</span> model and a larger Corynebacterium glutamicum model, were found to be in good agreement with those calculated by a previously published software. <span class="hlt">Flux</span>Pyt was tested in Microsoft™ Windows 7 and 10, as well as in Linux Mint 18.2. The availability of a free and open 13 C-MFA software that works in various operating systems will enable more researchers to perform 13 C-MFA and to further modify and develop the package.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5933345','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5933345"><span><span class="hlt">Flux</span>Pyt: a Python-based free and open-source software for 13C-metabolic <span class="hlt">flux</span> analyses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Desai, Trunil S.</p> <p>2018-01-01</p> <p>13C-Metabolic <span class="hlt">flux</span> analysis (MFA) is a powerful approach to estimate intracellular reaction rates which could be used in strain analysis and design. Processing and analysis of labeling data for calculation of <span class="hlt">fluxes</span> and associated statistics is an essential part of MFA. However, various software currently available for data analysis employ proprietary platforms and thus limit accessibility. We developed <span class="hlt">Flux</span>Pyt, a Python-based truly open-source software package for conducting stationary 13C-MFA data analysis. The software is based on the efficient elementary metabolite unit framework. The standard deviations in the calculated <span class="hlt">fluxes</span> are estimated using the Monte-Carlo analysis. <span class="hlt">Flux</span>Pyt also automatically creates <span class="hlt">flux</span> maps based on a template for visualization of the MFA results. The <span class="hlt">flux</span> distributions calculated by <span class="hlt">Flux</span>Pyt for two separate models: a small tricarboxylic acid <span class="hlt">cycle</span> model and a larger Corynebacterium glutamicum model, were found to be in good agreement with those calculated by a previously published software. <span class="hlt">Flux</span>Pyt was tested in Microsoft™ Windows 7 and 10, as well as in Linux Mint 18.2. The availability of a free and open 13C-MFA software that works in various operating systems will enable more researchers to perform 13C-MFA and to further modify and develop the package. PMID:29736347</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4121145','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4121145"><span>Simulating Metabolism with Statistical Thermodynamics</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cannon, William R.</p> <p>2014-01-01</p> <p>New methods are needed for large scale modeling of metabolism that predict metabolite levels and characterize the thermodynamics of individual reactions and pathways. Current approaches use either kinetic simulations, which are difficult to extend to large networks of reactions because of the need for rate constants, or <span class="hlt">flux</span>-based methods, which have a large number of feasible solutions because they are unconstrained by the law of mass action. This report presents an alternative modeling approach based on statistical thermodynamics. The principles of this approach are demonstrated using a simple set of coupled reactions, and then the system is characterized with respect to the changes in energy, entropy, free energy, and entropy production. Finally, the physical and biochemical insights that this approach can provide for metabolism are demonstrated by application to the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> of Escherichia coli. The reaction and pathway thermodynamics are evaluated and predictions are made regarding changes in concentration of <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates due to 10- and 100-fold changes in the ratio of NAD+:NADH concentrations. Finally, the assumptions and caveats regarding the use of statistical thermodynamics to model non-equilibrium reactions are discussed. PMID:25089525</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25089525','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25089525"><span>Simulating metabolism with statistical thermodynamics.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cannon, William R</p> <p>2014-01-01</p> <p>New methods are needed for large scale modeling of metabolism that predict metabolite levels and characterize the thermodynamics of individual reactions and pathways. Current approaches use either kinetic simulations, which are difficult to extend to large networks of reactions because of the need for rate constants, or <span class="hlt">flux</span>-based methods, which have a large number of feasible solutions because they are unconstrained by the law of mass action. This report presents an alternative modeling approach based on statistical thermodynamics. The principles of this approach are demonstrated using a simple set of coupled reactions, and then the system is characterized with respect to the changes in energy, entropy, free energy, and entropy production. Finally, the physical and biochemical insights that this approach can provide for metabolism are demonstrated by application to the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> of Escherichia coli. The reaction and pathway thermodynamics are evaluated and predictions are made regarding changes in concentration of <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates due to 10- and 100-fold changes in the ratio of NAD+:NADH concentrations. Finally, the assumptions and caveats regarding the use of statistical thermodynamics to model non-equilibrium reactions are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC21C1116G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC21C1116G"><span>High-resolution (30 m), annual (1986 - 2010) carbon stocks and <span class="hlt">fluxes</span> for southeastern US forests derived from remote sensing, inventory data, and a carbon <span class="hlt">cycle</span> model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gu, H.; Zhou, Y.; Williams, C. A.</p> <p>2016-12-01</p> <p>Disturbance events are highly heterogeneous in space and time, impacting forest carbon dynamics and challenging the quantification and reporting of carbon stocks and <span class="hlt">flux</span>. This study documents annual carbon stocks and <span class="hlt">fluxes</span> from 1986 and 2010 mapped at 30-m resolution across southeastern US forests, characterizing how they respond to disturbances and ensuing regrowth. Forest inventory data (FIA) are used to parameterize a carbon <span class="hlt">cycle</span> model (CASA) to represent post-disturbance carbon trajectories of carbon pools and <span class="hlt">fluxes</span> for harvest, fire and bark beetle disturbances of varying severity and across forest types and site productivity settings. Time since disturbance at 30 meters is inferred from two remote-sensing data sources: disturbance year (NAFD, MTBS and ADS) and biomass (NBCD 2000) intersected with inventory-derived curves of biomass accumulation with stand age. All of these elements are combined to map carbon stocks and <span class="hlt">fluxes</span> at a 30-m resolution for the year 2010, and to march backward in time for continuous, annual reporting. Results include maps of annual carbon stocks and <span class="hlt">fluxes</span> for forests of the southeastern US, and analysis of spatio-temporal patterns of carbon sources/sinks at local and regional scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1055855','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1055855"><span>Mitochondrial Respiration Can Support NO3− and NO2− Reduction during Photosynthesis 1</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Weger, Harold G.; Turpin, David H.</p> <p>1989-01-01</p> <p>Mass spectrometric analysis shows that assimilation of inorganic nitrogen (NH4+, NO2−, NO3−) by N-limited cells of Selenastrum minutum (Naeg.) Collins results in a stimulation of tricarboxylic acid <span class="hlt">cycle</span> (<span class="hlt">TCA</span> <span class="hlt">cycle</span>) CO2 release in both the light and dark. In a previous study we have shown that <span class="hlt">TCA</span> <span class="hlt">cycle</span> reductant generated during NH4+ assimilation is oxidized via the cytochrome electron transport chain, resulting in an increase in respiratory O2 consumption during photosynthesis (HG Weger, DG Birch, IR Elrifi, DH Turpin [1988] Plant Physiol 86: 688-692). NO3− and NO2− assimilation resulted in a larger stimulation of <span class="hlt">TCA</span> <span class="hlt">cycle</span> CO2 release than did NH4+, but a much smaller stimulation of mitochondrial O2 consumption. NH4+ assimilation was the same in the light and dark and insensitive to DCMU, but was 82% inhibited by anaerobiosis in both the light and dark. NO3− and NO2− assimilation rates were maximal in the light, but assimilation could proceed at substantial rates in the light in the presence of DCMU and in the dark. Unlike NH4+, NO3− and NO2− assimilation were relatively insensitive to anaerobiosis. These results indicated that operation of the mitochondrial electron transport chain was not required to maintain <span class="hlt">TCA</span> <span class="hlt">cycle</span> activity during NO3− and NO2− assimilation, suggesting an alternative sink for <span class="hlt">TCA</span> <span class="hlt">cycle</span> generated reductant. Evaluation of changes in gross O2 consumption during NO3− and NO2− assimilation suggest that <span class="hlt">TCA</span> <span class="hlt">cycle</span> reductant was exported to the chloroplast during photosynthesis and used to support NO3− and NO2− reduction. PMID:16666557</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4655539','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4655539"><span>Seasonal <span class="hlt">fluxes</span> of carbonyl sulfide in a midlatitude forest</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Commane, Róisín; Meredith, Laura K.; Baker, Ian T.; Berry, Joseph A.; Munger, J. William; Montzka, Stephen A.; Templer, Pamela H.; Juice, Stephanie M.; Zahniser, Mark S.; Wofsy, Steven C.</p> <p>2015-01-01</p> <p>Carbonyl sulfide (OCS), the most abundant sulfur gas in the atmosphere, has a summer minimum associated with uptake by vegetation and soils, closely correlated with CO2. We report the first direct measurements to our knowledge of the ecosystem <span class="hlt">flux</span> of OCS throughout an annual <span class="hlt">cycle</span>, at a mixed temperate forest. The forest took up OCS during most of the growing season with an overall uptake of 1.36 ± 0.01 mol OCS per ha (43.5 ± 0.5 g S per ha, 95% confidence intervals) for the year. Daytime <span class="hlt">fluxes</span> accounted for 72% of total uptake. Both soils and incompletely closed stomata in the canopy contributed to nighttime <span class="hlt">fluxes</span>. Unexpected net OCS emission occurred during the warmest weeks in summer. Many requirements necessary to use <span class="hlt">fluxes</span> of OCS as a simple estimate of photosynthesis were not met because OCS <span class="hlt">fluxes</span> did not have a constant relationship with photosynthesis throughout an entire day or over the entire year. However, OCS <span class="hlt">fluxes</span> provide a direct measure of ecosystem-scale stomatal conductance and mesophyll function, without relying on measures of soil evaporation or leaf temperature, and reveal previously unseen heterogeneity of forest canopy processes. Observations of OCS <span class="hlt">flux</span> provide powerful, independent means to test and refine land surface and carbon <span class="hlt">cycle</span> models at the ecosystem scale. PMID:26578759</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26578759','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26578759"><span>Seasonal <span class="hlt">fluxes</span> of carbonyl sulfide in a midlatitude forest.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Commane, Róisín; Meredith, Laura K; Baker, Ian T; Berry, Joseph A; Munger, J William; Montzka, Stephen A; Templer, Pamela H; Juice, Stephanie M; Zahniser, Mark S; Wofsy, Steven C</p> <p>2015-11-17</p> <p>Carbonyl sulfide (OCS), the most abundant sulfur gas in the atmosphere, has a summer minimum associated with uptake by vegetation and soils, closely correlated with CO2. We report the first direct measurements to our knowledge of the ecosystem <span class="hlt">flux</span> of OCS throughout an annual <span class="hlt">cycle</span>, at a mixed temperate forest. The forest took up OCS during most of the growing season with an overall uptake of 1.36 ± 0.01 mol OCS per ha (43.5 ± 0.5 g S per ha, 95% confidence intervals) for the year. Daytime <span class="hlt">fluxes</span> accounted for 72% of total uptake. Both soils and incompletely closed stomata in the canopy contributed to nighttime <span class="hlt">fluxes</span>. Unexpected net OCS emission occurred during the warmest weeks in summer. Many requirements necessary to use <span class="hlt">fluxes</span> of OCS as a simple estimate of photosynthesis were not met because OCS <span class="hlt">fluxes</span> did not have a constant relationship with photosynthesis throughout an entire day or over the entire year. However, OCS <span class="hlt">fluxes</span> provide a direct measure of ecosystem-scale stomatal conductance and mesophyll function, without relying on measures of soil evaporation or leaf temperature, and reveal previously unseen heterogeneity of forest canopy processes. Observations of OCS <span class="hlt">flux</span> provide powerful, independent means to test and refine land surface and carbon <span class="hlt">cycle</span> models at the ecosystem scale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=38769&Lab=NHEERL&keyword=Nuclear+AND+Radiation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=38769&Lab=NHEERL&keyword=Nuclear+AND+Radiation&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>BACTERIAL <span class="hlt">FLUX</span> FROM CHAPARRAL INTO THE ATMOSPHERE IN MID-SUMMER AT A HIGH DESERT LOCATION</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Estimates of the bacterial <span class="hlt">flux</span> for a daylight <span class="hlt">cycle</span> were observed at the Hanford Nuclear Reservation, Richland, WA, during June 1992, using a modified Bowen ratio method. he upward daytime bacterial <span class="hlt">flux</span> was coupled with the solar radiation/sensible heat <span class="hlt">cycle</span>, but commenced 2 h...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH11C..01M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH11C..01M"><span>Evolution of Our Understanding of the Solar Dynamo During Solar <span class="hlt">Cycle</span> 24</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Munoz-Jaramillo, A.</p> <p>2017-12-01</p> <p>Solar <span class="hlt">cycle</span> 24 has been an exciting <span class="hlt">cycle</span> for our understanding of the solar dynamo: 1. It was the first <span class="hlt">cycle</span> for which dynamo based predictions were ever used teaching us valuable lessons. 2. It has given us the opportunity to observe a deep minimum and a weak <span class="hlt">cycle</span> with a high level of of observational detail . 3. It is full of breaktrhoughs in anelastic MHD dynamo simulations (regular <span class="hlt">cycles</span>, buoyant <span class="hlt">flux</span>-tubes, mounder-like events). 4. It has seen the creation of bridges between the kinematic <span class="hlt">flux</span>-transport and anelastic MHD approaches. 5. It has ushered a new generation of realistic surface <span class="hlt">flux</span>-transport simulations 6. We have achieved significant observational progress in our understanding of solar <span class="hlt">cycle</span> propagation. The objective of this talk is to highlight some of the most important results, giving special emphasis on what they have taught us about solar <span class="hlt">cycle</span> predictability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21277056','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21277056"><span>Quantification of net carbon <span class="hlt">flux</span> from plastic greenhouse vegetable cultivation: a full carbon <span class="hlt">cycle</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yan; Xu, Hao; Wu, Xu; Zhu, Yimei; Gu, Baojing; Niu, Xiaoyin; Liu, Anqin; Peng, Changhui; Ge, Ying; Chang, Jie</p> <p>2011-05-01</p> <p>Plastic greenhouse vegetable cultivation (PGVC) has played a vital role in increasing incomes of farmers and expanded dramatically in last several decades. However, carbon budget after conversion from conventional vegetable cultivation (CVC) to PGVC has been poorly quantified. A full carbon <span class="hlt">cycle</span> analysis was used to estimate the net carbon <span class="hlt">flux</span> from PGVC systems based on the combination of data from both field observations and literatures. Carbon fixation was evaluated at two pre-selected locations in China. Results suggest that: (1) the carbon sink of PGVC is 1.21 and 1.23 Mg C ha(-1) yr(-1) for temperate and subtropical area, respectively; (2) the conversion from CVC to PGVC could substantially enhance carbon sink potential by 8.6 times in the temperate area and by 1.3 times in the subtropical area; (3) the expansion of PGVC usage could enhance the potential carbon sink of arable land in China overall. Copyright © 2011 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=319938','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=319938"><span>Threshold wind velocity dynamics as a driver of aeolian sediment mas <span class="hlt">flux</span></span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Horizontal (saltation) mass <span class="hlt">flux</span> is a key driver of aeolian dust emission. Estimates of the horizontal mass <span class="hlt">flux</span> underpin assessments of the global dust budget and influence our understanding of the dust <span class="hlt">cycle</span> and its interactions. Current equations for predicting horizontal mass <span class="hlt">flux</span> are based on l...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24596328','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24596328"><span>A Diel <span class="hlt">Flux</span> Balance Model Captures Interactions between Light and Dark Metabolism during Day-Night <span class="hlt">Cycles</span> in C3 and Crassulacean Acid Metabolism Leaves.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheung, C Y Maurice; Poolman, Mark G; Fell, David A; Ratcliffe, R George; Sweetlove, Lee J</p> <p>2014-06-01</p> <p>Although leaves have to accommodate markedly different metabolic <span class="hlt">flux</span> patterns in the light and the dark, models of leaf metabolism based on <span class="hlt">flux</span>-balance analysis (FBA) have so far been confined to consideration of the network under continuous light. An FBA framework is presented that solves the two phases of the diel <span class="hlt">cycle</span> as a single optimization problem and, thus, provides a more representative model of leaf metabolism. The requirement to support continued export of sugar and amino acids from the leaf during the night and to meet overnight cellular maintenance costs forces the model to set aside stores of both carbon and nitrogen during the day. With only minimal constraints, the model successfully captures many of the known features of C 3 leaf metabolism, including the recently discovered role of citrate synthesis and accumulation in the night as a precursor for the provision of carbon skeletons for amino acid synthesis during the day. The diel FBA model can be applied to other temporal separations, such as that which occurs in Crassulacean acid metabolism (CAM) photosynthesis, allowing a system-level analysis of the energetics of CAM. The diel model predicts that there is no overall energetic advantage to CAM, despite the potential for suppression of photorespiration through CO 2 concentration. Moreover, any savings in enzyme machinery costs through suppression of photorespiration are likely to be offset by the higher <span class="hlt">flux</span> demand of the CAM <span class="hlt">cycle</span>. It is concluded that energetic or nitrogen use considerations are unlikely to be evolutionary drivers for CAM photosynthesis. © 2014 American Society of Plant Biologists. All Rights Reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/12079062','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/12079062"><span>Trichloroacetic acid in the environment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCulloch, A</p> <p>2002-05-01</p> <p>Suppositions that the trichloroacetic acid (<span class="hlt">TCA</span>, CCl3C(O)OH) found in nature was a consequence solely of the use of chlorinated hydrocarbon solvents prompted this critical review of the literature on its environmental <span class="hlt">fluxes</span> and occurrences. <span class="hlt">TCA</span> is widely distributed in forest soils (where it was rarely used as an herbicide) and measurements suggest a soil <span class="hlt">flux</span> of 160 000 tonnes yr(-1) in European forests alone. <span class="hlt">TCA</span> is also produced during oxidative water treatment and the global <span class="hlt">flux</span> could amount to 55 000 tonnes yr(-1) (from pulp and paper manufacture, potable water and cooling water treatments). By contrast, the yields of <span class="hlt">TCA</span> from chlorinated hydrocarbon solvents are small: from tetrachloroethene 13 600 tonnes yr(-1) and from 1,1,1-trichloroethane 4300 tonnes yr(-1) on a global basis, at the atmospheric burdens and removal rates typical of the late 1990s. <span class="hlt">TCA</span> is ubiquitous in rainwater and snow. Its concentrations are highly variable and the variations cannot be connected with location or date. However, there is no significant difference between the concentrations found in Chile and in eastern Canada (by the same analysts), or between Malawi and western Canada, or between Antarctica and Switzerland, nor any significant difference globally between the concentrations in cloud, rain and snow (although local enhancement in fog water has been shown). <span class="hlt">TCA</span> is present in old ice and firn. At the deepest levels, the firn was deposited early in the 19th century, well before the possibility of contamination by industrial production of reactive chlorine, implying a non-industrial background. This proposition is supported by plume measurements from pulp mills in Finland. <span class="hlt">TCA</span> is ubiquitous in soils; concentrations are very variable but there are some indications that soils under coniferous trees contain higher amounts. The concentrations of <span class="hlt">TCA</span> found in plant tissue are region-specific and may also be plant-specific, to the extent that conifers seem to contain more than other</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017A%26A...607L...2I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017A%26A...607L...2I"><span>Improvement of solar-<span class="hlt">cycle</span> prediction: Plateau of solar axial dipole moment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Iijima, H.; Hotta, H.; Imada, S.; Kusano, K.; Shiota, D.</p> <p>2017-11-01</p> <p>Aims: We report the small temporal variation of the axial dipole moment near the solar minimum and its application to the solar-<span class="hlt">cycle</span> prediction by the surface <span class="hlt">flux</span> transport (SFT) model. Methods: We measure the axial dipole moment using the photospheric synoptic magnetogram observed by the Wilcox Solar Observatory (WSO), the ESA/NASA Solar and Heliospheric Observatory Michelson Doppler Imager (MDI), and the NASA Solar Dynamics Observatory Helioseismic and Magnetic Imager (HMI). We also use the SFT model for the interpretation and prediction of the observed axial dipole moment. Results: We find that the observed axial dipole moment becomes approximately constant during the period of several years before each <span class="hlt">cycle</span> minimum, which we call the axial dipole moment plateau. The cross-equatorial magnetic <span class="hlt">flux</span> transport is found to be small during the period, although a significant number of sunspots are still emerging. The results indicate that the newly emerged magnetic <span class="hlt">flux</span> does not contribute to the build up of the axial dipole moment near the end of each <span class="hlt">cycle</span>. This is confirmed by showing that the time variation of the observed axial dipole moment agrees well with that predicted by the SFT model without introducing new emergence of magnetic <span class="hlt">flux</span>. These results allow us to predict the axial dipole moment at the <span class="hlt">Cycle</span> 24/25 minimum using the SFT model without introducing new <span class="hlt">flux</span> emergence. The predicted axial dipole moment at the <span class="hlt">Cycle</span> 24/25 minimum is 60-80 percent of <span class="hlt">Cycle</span> 23/24 minimum, which suggests the amplitude of <span class="hlt">Cycle</span> 25 is even weaker than the current <span class="hlt">Cycle</span> 24. Conclusions: The plateau of the solar axial dipole moment is an important feature for the longer-term prediction of the solar <span class="hlt">cycle</span> based on the SFT model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150001279','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150001279"><span>Quantifying the Observability of CO2 <span class="hlt">Flux</span> Uncertainty in Atmospheric CO2 Records Using Products from Nasa's Carbon Monitoring <span class="hlt">Flux</span> Pilot Project</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ott, Lesley; Pawson, Steven; Collatz, Jim; Watson, Gregg; Menemenlis, Dimitris; Brix, Holger; Rousseaux, Cecile; Bowman, Kevin; Bowman, Kevin; Liu, Junjie; <a style="text-decoration: none; " href="javascript:void(0); " onClick="displayelement('author_20150001279'); toggleEditAbsImage('author_20150001279_show'); toggleEditAbsImage('author_20150001279_hide'); "> <img style="display:inline; width:12px; height:12px; " src="images/arrow-up.gif" width="12" height="12" border="0" alt="hide" id="author_20150001279_show"> <img style="width:12px; height:12px; display:none; " src="images/arrow-down.gif" width="12" height="12" border="0" alt="hide" id="author_20150001279_hide"></p> <p>2014-01-01</p> <p>NASAs Carbon Monitoring System (CMS) <span class="hlt">Flux</span> Pilot Project (FPP) was designed to better understand contemporary carbon <span class="hlt">fluxes</span> by bringing together state-of-the art models with remote sensing datasets. Here we report on simulations using NASAs Goddard Earth Observing System Model, version 5 (GEOS-5) which was used to evaluate the consistency of two different sets of observationally constrained land and ocean <span class="hlt">fluxes</span> with atmospheric CO2 records. Despite the strong data constraint, the average difference in annual terrestrial biosphere <span class="hlt">flux</span> between the two land (NASA Ames CASA and CASA-GFED) models is 1.7 Pg C for 2009-2010. Ocean models (NOBM and ECCO2-Darwin) differ by 35 in their global estimates of carbon <span class="hlt">flux</span> with particularly strong disagreement in high latitudes. Based upon combinations of terrestrial and ocean <span class="hlt">fluxes</span>, GEOS-5 reasonably simulated the seasonal <span class="hlt">cycle</span> observed at northern hemisphere surface sites and by the Greenhouse gases Observing SATellite (GOSAT) while the model struggled to simulate the seasonal <span class="hlt">cycle</span> at southern hemisphere surface locations. Though GEOS-5 was able to reasonably reproduce the patterns of XCO2 observed by GOSAT, it struggled to reproduce these aspects of AIRS observations. Despite large differences between land and ocean <span class="hlt">flux</span> estimates, resulting differences in atmospheric mixing ratio were small, typically less than 5 ppmv at the surface and 3 ppmv in the XCO2 column. A statistical analysis based on the variability of observations shows that <span class="hlt">flux</span> differences of these magnitudes are difficult to distinguish from natural variability, regardless of measurement platform.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B22E..05F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B22E..05F"><span>Quantifying the impacts of piñon mortality on ecosystem-scale carbon and water <span class="hlt">cycling</span>: a twinned <span class="hlt">flux</span> tower approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fox, A. M.; Litvak, M. E.; McDowell, N.; Rahn, T.; Ryan, M. G.</p> <p>2010-12-01</p> <p>Piñon-juniper (PJ) woodlands, which occupy 24 million ha throughout the Southwest, proved to be extremely vulnerable to an extended drought that began in 1999, leading to an abrupt die-off of 40 to 95% of piñon pine (Pinus edulis) and 2-25% of juniper (Juniperus monosperma) in less than 3 years. Climate predictions for the region suggest such droughts are likely to become more frequent and widespread in the future, extending northwards. Such large-scale change in vegetation has the potential to trigger rapid changes in ecosystem carbon dynamics and the local and regional hydrologic <span class="hlt">cycle</span>. We are using a twinned ecosystem-scale manipulation study to quantify the transient dynamics of carbon and water <span class="hlt">flux</span> responses to piñon mortality. A combination of eddy covariance, soil respiration and moisture, sap flow and biomass carbon pool measurements are being made at an undisturbed PJ woodland (control) site and at a manipulation site within 2 miles of the control where all piñon trees greater than 7 cm diameter at breast height within the 4 ha <span class="hlt">flux</span> footprint were killed in September 2009 using girdling and herbicide injection following 6 months of background measurements. We hypothesis that piñon mortality alters the local scale carbon <span class="hlt">cycle</span> by shifting a large stock of carbon from productive biomass to detritus, leading to an initial decrease in net primary production and an increase in ecosystem respiration and net carbon <span class="hlt">flux</span> to the atmosphere. However, reduced competition for water in these water-limited ecosystems and increased light availability may lead to compensatory growth in surviving small piñon, juniper and understory vegetation, offsetting or exceeding the expected reduction in NPP from piñon mortality. Because litter and coarse woody debris are slow to decompose in semiarid environments we hypothesize that the manipulation site will continue to be net carbon sources even after NPP recovers. Our general hypothesis for the local scale water <span class="hlt">cycle</span> is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4321164','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4321164"><span>Sulphur geodynamic <span class="hlt">cycle</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Kagoshima, Takanori; Sano, Yuji; Takahata, Naoto; Maruoka, Teruyuki; Fischer, Tobias P.; Hattori, Keiko</p> <p>2015-01-01</p> <p>Evaluation of volcanic and hydrothermal <span class="hlt">fluxes</span> to the surface environments is important to elucidate the geochemical <span class="hlt">cycle</span> of sulphur and the evolution of ocean chemistry. This paper presents S/3He ratios of vesicles in mid-ocean ridge (MOR) basalt glass together with the ratios of high-temperature hydrothermal fluids to calculate the sulphur <span class="hlt">flux</span> of 100 Gmol/y at MOR. The S/3He ratios of high-temperature volcanic gases show sulphur <span class="hlt">flux</span> of 720 Gmol/y at arc volcanoes (ARC) with a contribution from the mantle of 2.9%, which is calculated as 21 Gmol/y. The C/S <span class="hlt">flux</span> ratio of 12 from the mantle at MOR and ARC is comparable to the C/S ratio in the surface inventory, which suggests that these elements in the surface environments originated from the upper mantle. PMID:25660256</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29624613','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29624613"><span>Quantifying differences in water and carbon <span class="hlt">cycling</span> between paddy and rainfed rice (Oryza sativa L.) by <span class="hlt">flux</span> partitioning.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nay-Htoon, Bhone; Xue, Wei; Lindner, Steve; Cuntz, Matthias; Ko, Jonghan; Tenhunen, John; Werner, Christiane; Dubbert, Maren</p> <p>2018-01-01</p> <p>Agricultural crops play an important role in the global carbon and water <span class="hlt">cycle</span>. Global climate change scenarios predict enhanced water scarcity and altered precipitation pattern in many parts of the world. Hence, a mechanistic understanding of water <span class="hlt">fluxes</span>, productivity and water use efficiency of cultivated crops is of major importance, i.e. to adapt management practices. We compared water and carbon <span class="hlt">fluxes</span> of paddy and rainfed rice by canopy scale gas exchange measurements, crop growth, daily evapotranspiration, transpiration and carbon <span class="hlt">flux</span> modeling. Throughout a monsoon rice growing season, soil evaporation in paddy rice contributed strongly to evapotranspiration (96.6% to 43.3% from initial growth to fully developed canopy and amounted to 57.9% of total water losses over the growing seasons. Evaporation of rainfed rice was significantly lower (by 65% on average) particularly before canopy closure. Water use efficiency (WUE) was significantly higher in rainfed rice both from an agronomic (WUEagro, i.e. grain yield per evapotranspiration) and ecosystem (WUEeco, i.e. gross primary production per evapotranspiration) perspective. However, our results also show that higher WUE in rainfed rice comes at the expense of higher respiration losses compared to paddy rice (26% higher on average). Hence, suggestions on water management depend on the regional water availability (i.e. Mediterranean vs. Monsoon climate) and the balance between higher respiratory losses versus a potential reduction in CH4 and other greenhouse gas emissions. Our results suggest that a shift from rainfed/unsaturated soil to waterlogged paddy conditions after closure of the rice canopy might be a good compromise towards a sustainable use of water while preserving grain yield, particularly for water-limited production areas.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5889072','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5889072"><span>Quantifying differences in water and carbon <span class="hlt">cycling</span> between paddy and rainfed rice (Oryza sativa L.) by <span class="hlt">flux</span> partitioning</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nay‐Htoon, Bhone; Xue, Wei; Lindner, Steve; Cuntz, Matthias; Ko, Jonghan; Tenhunen, John; Werner, Christiane</p> <p>2018-01-01</p> <p>Agricultural crops play an important role in the global carbon and water <span class="hlt">cycle</span>. Global climate change scenarios predict enhanced water scarcity and altered precipitation pattern in many parts of the world. Hence, a mechanistic understanding of water <span class="hlt">fluxes</span>, productivity and water use efficiency of cultivated crops is of major importance, i.e. to adapt management practices. We compared water and carbon <span class="hlt">fluxes</span> of paddy and rainfed rice by canopy scale gas exchange measurements, crop growth, daily evapotranspiration, transpiration and carbon <span class="hlt">flux</span> modeling. Throughout a monsoon rice growing season, soil evaporation in paddy rice contributed strongly to evapotranspiration (96.6% to 43.3% from initial growth to fully developed canopy and amounted to 57.9% of total water losses over the growing seasons. Evaporation of rainfed rice was significantly lower (by 65% on average) particularly before canopy closure. Water use efficiency (WUE) was significantly higher in rainfed rice both from an agronomic (WUEagro, i.e. grain yield per evapotranspiration) and ecosystem (WUEeco, i.e. gross primary production per evapotranspiration) perspective. However, our results also show that higher WUE in rainfed rice comes at the expense of higher respiration losses compared to paddy rice (26% higher on average). Hence, suggestions on water management depend on the regional water availability (i.e. Mediterranean vs. Monsoon climate) and the balance between higher respiratory losses versus a potential reduction in CH4 and other greenhouse gas emissions. Our results suggest that a shift from rainfed/unsaturated soil to waterlogged paddy conditions after closure of the rice canopy might be a good compromise towards a sustainable use of water while preserving grain yield, particularly for water-limited production areas. PMID:29624613</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22370206-solar-photospheric-network-properties-cycle-variation','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22370206-solar-photospheric-network-properties-cycle-variation"><span>Solar photospheric network properties and their <span class="hlt">cycle</span> variation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Thibault, K.; Charbonneau, P.; Béland, M., E-mail: kim@astro.umontreal.ca-a, E-mail: paulchar@astro.umontreal.ca-b, E-mail: michel.beland@calculquebec.ca-c</p> <p></p> <p>We present a numerical simulation of the formation and evolution of the solar photospheric magnetic network over a full solar <span class="hlt">cycle</span>. The model exhibits realistic behavior as it produces large, unipolar concentrations of <span class="hlt">flux</span> in the polar caps, a power-law <span class="hlt">flux</span> distribution with index –1.69, a <span class="hlt">flux</span> replacement timescale of 19.3 hr, and supergranule diameters of 20 Mm. The polar behavior is especially telling of model accuracy, as it results from lower-latitude activity, and accumulates the residues of any potential modeling inaccuracy and oversimplification. In this case, the main oversimplification is the absence of a polar sink for the <span class="hlt">flux</span>,more » causing an amount of polar cap unsigned <span class="hlt">flux</span> larger than expected by almost one order of magnitude. Nonetheless, our simulated polar caps carry the proper signed <span class="hlt">flux</span> and dipole moment, and also show a spatial distribution of <span class="hlt">flux</span> in good qualitative agreement with recent high-latitude magnetographic observations by Hinode. After the last <span class="hlt">cycle</span> emergence, the simulation is extended until the network has recovered its quiet Sun initial condition. This permits an estimate of the network relaxation time toward the baseline state characterizing extended periods of suppressed activity, such as the Maunder Grand Minimum. Our simulation results indicate a network relaxation time of 2.9 yr, setting 2011 October as the soonest the time after which the last solar activity minimum could have qualified as a Maunder-type Minimum. This suggests that photospheric magnetism did not reach its baseline state during the recent extended minimum between <span class="hlt">cycles</span> 23 and 24.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4045150','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4045150"><span>Urinary Loss of Tricarboxylic Acid <span class="hlt">Cycle</span> Intermediates As Revealed by Metabolomics Studies: An Underlying Mechanism to Reduce Lipid Accretion by Whey Protein Ingestion?</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2015-01-01</p> <p>Whey protein intake is associated with the modulation of energy metabolism and altered body composition both in human subjects and in animals, but the underlying mechanisms are not yet elucidated. We fed obesity-prone C57BL/6J mice high-fat diets with either casein (HF casein) or whey (HF whey) for 6 weeks. At equal energy intake and apparent fat and nitrogen digestibility, mice fed HF whey stored less energy as lipids, evident both as lower white adipose tissue mass and as reduced liver lipids, compared with HF-casein-fed mice. Explorative analyses of 48 h urine, both by 1H NMR and LC–MS metabolomic platforms, demonstrated higher urinary excretion of tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediates citric acid and succinic acid (identified by both platforms), and cis-aconitic acid and isocitric acid (identified by LC–MS platform) in the HF whey, relative to in the HF-casein-fed mice. Targeted LC–MS analyses revealed higher citric acid and cis-aconitic acid concentrations in fed state plasma, but not in liver of HF-whey-fed mice. We propose that enhanced urinary loss of <span class="hlt">TCA</span> <span class="hlt">cycle</span> metabolites drain available substrates for anabolic processes, such as lipogenesis, thereby leading to reduced lipid accretion in HF-whey-fed compared to HF-casein-fed mice. PMID:24702026</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3068929','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3068929"><span>Reactive Oxygen Species Production by Forward and Reverse Electron <span class="hlt">Fluxes</span> in the Mitochondrial Respiratory Chain</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Selivanov, Vitaly A.; Votyakova, Tatyana V.; Pivtoraiko, Violetta N.; Zeak, Jennifer; Sukhomlin, Tatiana; Trucco, Massimo; Roca, Josep; Cascante, Marta</p> <p>2011-01-01</p> <p>Reactive oxygen species (ROS) produced in the mitochondrial respiratory chain (RC) are primary signals that modulate cellular adaptation to environment, and are also destructive factors that damage cells under the conditions of hypoxia/reoxygenation relevant for various systemic diseases or transplantation. The important role of ROS in cell survival requires detailed investigation of mechanism and determinants of ROS production. To perform such an investigation we extended our rule-based model of complex III in order to account for electron transport in the whole RC coupled to proton translocation, transmembrane electrochemical potential generation, <span class="hlt">TCA</span> <span class="hlt">cycle</span> reactions, and substrate transport to mitochondria. It fits respiratory electron <span class="hlt">fluxes</span> measured in rat brain mitochondria fueled by succinate or pyruvate and malate, and the dynamics of NAD+ reduction by reverse electron transport from succinate through complex I. The fitting of measured characteristics gave an insight into the mechanism of underlying processes governing the formation of free radicals that can transfer an unpaired electron to oxygen-producing superoxide and thus can initiate the generation of ROS. Our analysis revealed an association of ROS production with levels of specific radicals of individual electron transporters and their combinations in species of complexes I and III. It was found that the phenomenon of bistability, revealed previously as a property of complex III, remains valid for the whole RC. The conditions for switching to a state with a high content of free radicals in complex III were predicted based on theoretical analysis and were confirmed experimentally. These findings provide a new insight into the mechanisms of ROS production in RC. PMID:21483483</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20130013047','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20130013047"><span>Diary of a Wimpy <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David; Upton, Lisa</p> <p>2013-01-01</p> <p>The cause of the low and extended minimum in solar activity between Sunspot <span class="hlt">Cycles</span> 23 and 24 was the small size of Sunspot <span class="hlt">Cycle</span> 24 itself - small <span class="hlt">cycles</span> start late and leave behind low minima. <span class="hlt">Cycle</span> 24 is small because the polar fields produced during <span class="hlt">Cycle</span> 23 were substantially weaker than those produced during the previous <span class="hlt">cycles</span> and those (weak) polar fields are the seeds for the activity of the following <span class="hlt">cycle</span>. Here we discuss the observed characteristics of <span class="hlt">Cycle</span> 24 and contrast them to the characteristics of previous <span class="hlt">cycles</span>. We present observations and Magnetic <span class="hlt">Flux</span> Transport simulations with data assimilated from SOHO/MDI and SDO/HMI that help to explain these differences and point the way to predictions of future activity levels.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000ApJ...543.1027C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000ApJ...543.1027C"><span>Stochastic Fluctuations in a Babcock-Leighton Model of the Solar <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Charbonneau, Paul; Dikpati, Mausumi</p> <p>2000-11-01</p> <p>We investigate the effect of stochastic fluctuations on a <span class="hlt">flux</span> transport model of the solar <span class="hlt">cycle</span> based on the Babcock-Leighton mechanism. Specifically, we make use of our recent <span class="hlt">flux</span> transport model (Dikpati & Charbonneau) to investigate the consequences of introducing large-amplitude stochastic fluctuations in either or both the meridional flow and poloidal source term in the model. Solar <span class="hlt">cycle</span>-like oscillatory behavior persists even for fluctuation amplitudes as high as 300%, thus demonstrating the inherent robustness of this class of solar <span class="hlt">cycle</span> models. We also find that high-amplitude fluctuations lead to a spread of <span class="hlt">cycle</span> amplitude and duration showing a statistically significant anticorrelation, comparable to that observed in sunspot data. This is a feature of the solar <span class="hlt">cycle</span> that is notoriously difficult to reproduce with dynamo models based on mean field electrodynamics and relying only on nonlinearities associated with the back-reaction of the Lorentz force to produce amplitude modulation. Another noteworthy aspect of our <span class="hlt">flux</span> transport model is the fact that meridional circulation in the convective envelope acts as a ``clock'' regulating the tempo of the solar <span class="hlt">cycle</span>; shorter-than-average <span class="hlt">cycles</span> are typically soon followed by longer-than-average <span class="hlt">cycles</span>. In other words, the oscillation exhibits good phase locking, a property that also characterizes the solar activity <span class="hlt">cycle</span>. This shows up quite clearly in our model, but we argue that it is in fact a generic property of <span class="hlt">flux</span> transport models based on the Babcock-Leighton mechanism, and relies on meridional circulation as the primary magnetic field transport agent.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5561298','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5561298"><span>Metabolic Engineering of Actinobacillus succinogenes Provides Insights into Succinic Acid Biosynthesis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Guarnieri, Michael T.; Chou, Yat-Chen; Salvachúa, Davinia; Mohagheghi, Ali; St. John, Peter C.; Peterson, Darren J.; Bomble, Yannick J.</p> <p>2017-01-01</p> <p>ABSTRACT Actinobacillus succinogenes, a Gram-negative facultative anaerobe, exhibits the native capacity to convert pentose and hexose sugars to succinic acid (SA) with high yield as a tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediate. In addition, A. succinogenes is capnophilic, incorporating CO2 into SA, making this organism an ideal candidate host for conversion of lignocellulosic sugars and CO2 to an emerging commodity bioproduct sourced from renewable feedstocks. In this work, we report the development of facile metabolic engineering capabilities in A. succinogenes, enabling examination of SA <span class="hlt">flux</span> determinants via knockout of the primary competing pathways—namely, acetate and formate production—and overexpression of the key enzymes in the reductive branch of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> leading to SA. Batch fermentation experiments with the wild-type and engineered strains using pentose-rich sugar streams demonstrate that the overexpression of the SA biosynthetic machinery (in particular, the enzyme malate dehydrogenase) enhances <span class="hlt">flux</span> to SA. Additionally, removal of competitive carbon pathways leads to higher-purity SA but also triggers the generation of by-products not previously described from this organism (e.g., lactic acid). The resultant engineered strains also lend insight into energetic and redox balance and elucidate mechanisms governing organic acid biosynthesis in this important natural SA-producing microbe. IMPORTANCE Succinic acid production from lignocellulosic residues is a potential route for enhancing the economic feasibility of modern biorefineries. Here, we employ facile genetic tools to systematically manipulate competing acid production pathways and overexpress the succinic acid-producing machinery in Actinobacillus succinogenes. Furthermore, the resulting strains are evaluated via fermentation on relevant pentose-rich sugar streams representative of those from corn stover. Overall, this work demonstrates genetic modifications that can lead to succinic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28625987','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28625987"><span>Metabolic Engineering of Actinobacillus succinogenes Provides Insights into Succinic Acid Biosynthesis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guarnieri, Michael T; Chou, Yat-Chen; Salvachúa, Davinia; Mohagheghi, Ali; St John, Peter C; Peterson, Darren J; Bomble, Yannick J; Beckham, Gregg T</p> <p>2017-09-01</p> <p>Actinobacillus succinogenes , a Gram-negative facultative anaerobe, exhibits the native capacity to convert pentose and hexose sugars to succinic acid (SA) with high yield as a tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediate. In addition, A. succinogenes is capnophilic, incorporating CO 2 into SA, making this organism an ideal candidate host for conversion of lignocellulosic sugars and CO 2 to an emerging commodity bioproduct sourced from renewable feedstocks. In this work, we report the development of facile metabolic engineering capabilities in A. succinogenes , enabling examination of SA <span class="hlt">flux</span> determinants via knockout of the primary competing pathways-namely, acetate and formate production-and overexpression of the key enzymes in the reductive branch of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> leading to SA. Batch fermentation experiments with the wild-type and engineered strains using pentose-rich sugar streams demonstrate that the overexpression of the SA biosynthetic machinery (in particular, the enzyme malate dehydrogenase) enhances <span class="hlt">flux</span> to SA. Additionally, removal of competitive carbon pathways leads to higher-purity SA but also triggers the generation of by-products not previously described from this organism (e.g., lactic acid). The resultant engineered strains also lend insight into energetic and redox balance and elucidate mechanisms governing organic acid biosynthesis in this important natural SA-producing microbe. IMPORTANCE Succinic acid production from lignocellulosic residues is a potential route for enhancing the economic feasibility of modern biorefineries. Here, we employ facile genetic tools to systematically manipulate competing acid production pathways and overexpress the succinic acid-producing machinery in Actinobacillus succinogenes Furthermore, the resulting strains are evaluated via fermentation on relevant pentose-rich sugar streams representative of those from corn stover. Overall, this work demonstrates genetic modifications that can lead to succinic acid</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1395092','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1395092"><span>Metabolic Engineering of Actinobacillus succinogenes Provides Insights into Succinic Acid Biosynthesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Guarnieri, Michael T.; Chou, Yat -Chen; Salvachua, Davinia Rodriquez</p> <p></p> <p>Actinobacillus succinogenes, a Gram-negative facultative anaerobe, exhibits the native capacity to convert pentose and hexose sugars to succinic acid (SA) with high yield as a tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediate. In addition, A. succinogenes is capnophilic, incorporating CO 2 into SA, making this organism an ideal candidate host for conversion of lignocellulosic sugars and CO 2 to an emerging commodity bioproduct sourced from renewable feedstocks. In this work, we report the development of facile metabolic engineering capabilities in A. succinogenes, enabling examination of SA <span class="hlt">flux</span> determinants via knockout of the primary competing pathways—namely, acetate and formate production—and overexpression of themore » key enzymes in the reductive branch of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> leading to SA. Batch fermentation experiments with the wild-type and engineered strains using pentose-rich sugar streams demonstrate that the overexpression of the SA biosynthetic machinery (in particular, the enzyme malate dehydrogenase) enhances <span class="hlt">flux</span> to SA. Additionally, removal of competitive carbon pathways leads to higher-purity SA but also triggers the generation of by-products not previously described from this organism (e.g., lactic acid). The resultant engineered strains also lend insight into energetic and redox balance and elucidate mechanisms governing organic acid biosynthesis in this important natural SA-producing microbe. IMPORTANCE Succinic acid production from lignocellulosic residues is a potential route for enhancing the economic feasibility of modern biorefineries. Here, we employ facile genetic tools to systematically manipulate competing acid production pathways and overexpress the succinic acid-producing machinery in Actinobacillus succinogenes. Furthermore, the resulting strains are evaluated via fermentation on relevant pentose-rich sugar streams representative of those from corn stover. Altogether, this work demonstrates genetic modifications that can lead to succinic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1395092-metabolic-engineering-actinobacillus-succinogenes-provides-insights-succinic-acid-biosynthesis','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1395092-metabolic-engineering-actinobacillus-succinogenes-provides-insights-succinic-acid-biosynthesis"><span>Metabolic Engineering of Actinobacillus succinogenes Provides Insights into Succinic Acid Biosynthesis</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Guarnieri, Michael T.; Chou, Yat -Chen; Salvachua, Davinia Rodriquez; ...</p> <p>2017-06-16</p> <p>Actinobacillus succinogenes, a Gram-negative facultative anaerobe, exhibits the native capacity to convert pentose and hexose sugars to succinic acid (SA) with high yield as a tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> intermediate. In addition, A. succinogenes is capnophilic, incorporating CO 2 into SA, making this organism an ideal candidate host for conversion of lignocellulosic sugars and CO 2 to an emerging commodity bioproduct sourced from renewable feedstocks. In this work, we report the development of facile metabolic engineering capabilities in A. succinogenes, enabling examination of SA <span class="hlt">flux</span> determinants via knockout of the primary competing pathways—namely, acetate and formate production—and overexpression of themore » key enzymes in the reductive branch of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> leading to SA. Batch fermentation experiments with the wild-type and engineered strains using pentose-rich sugar streams demonstrate that the overexpression of the SA biosynthetic machinery (in particular, the enzyme malate dehydrogenase) enhances <span class="hlt">flux</span> to SA. Additionally, removal of competitive carbon pathways leads to higher-purity SA but also triggers the generation of by-products not previously described from this organism (e.g., lactic acid). The resultant engineered strains also lend insight into energetic and redox balance and elucidate mechanisms governing organic acid biosynthesis in this important natural SA-producing microbe. IMPORTANCE Succinic acid production from lignocellulosic residues is a potential route for enhancing the economic feasibility of modern biorefineries. Here, we employ facile genetic tools to systematically manipulate competing acid production pathways and overexpress the succinic acid-producing machinery in Actinobacillus succinogenes. Furthermore, the resulting strains are evaluated via fermentation on relevant pentose-rich sugar streams representative of those from corn stover. Altogether, this work demonstrates genetic modifications that can lead to succinic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28799942','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28799942"><span>Effect of <span class="hlt">cycle</span> run time of backwash and relaxation on membrane fouling removal in submerged membrane bioreactor treating sewage at higher <span class="hlt">flux</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tabraiz, Shamas; Haydar, Sajjad; Sallis, Paul; Nasreen, Sadia; Mahmood, Qaisar; Awais, Muhammad; Acharya, Kishor</p> <p>2017-08-01</p> <p>Intermittent backwashing and relaxation are mandatory in the membrane bioreactor (MBR) for its effective operation. The objective of the current study was to evaluate the effects of run-relaxation and run-backwash <span class="hlt">cycle</span> time on fouling rates. Furthermore, comparison of the effects of backwashing and relaxation on the fouling behavior of membrane in high rate submerged MBR. The study was carried out on a laboratory scale MBR at high <span class="hlt">flux</span> (30 L/m 2 ·h), treating sewage. The MBR was operated at three relaxation operational scenarios by keeping the run time to relaxation time ratio constant. Similarly, the MBR was operated at three backwashing operational scenarios by keeping the run time to backwashing time ratio constant. The results revealed that the provision of relaxation or backwashing at small intervals prolonged the MBR operation by reducing fouling rates. The cake and pores fouling rates in backwashing scenarios were far less as compared to the relaxation scenarios, which proved backwashing a better option as compared to relaxation. The operation time of backwashing scenario (lowest <span class="hlt">cycle</span> time) was 64.6% and 21.1% more as compared to continuous scenario and relaxation scenario (lowest <span class="hlt">cycle</span> time), respectively. Increase in <span class="hlt">cycle</span> time increased removal efficiencies insignificantly, in both scenarios of relaxation and backwashing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011PhDT........20F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011PhDT........20F"><span>Dislocation Density Reduction in Cadmium Telluride and Mercury Cadmium Telluride Grown on Silicon Using Thermal <span class="hlt">Cycle</span> Annealing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Farrell, Stuart Bennett</p> <p></p> <p>Mercury Cadmium Telluride (HgCdTe) is a material of great importance for infrared focal plane array applications. In order to produce large format detector arrays this material needs to be grown on a large area substrate, with silicon being the most mature substrate, it is the optimal choice for large format arrays. To help mitigate the effect of the lattice mismatch between the two materials, cadmium telluride (CdTe) is used as a buffer layer. The CdTe itself has nearly the same lattice mismatch (19.3%) to silicon, but due to the technological advantages it offers and compatibility with HgCdTe, it is the best buffer layer choice. The lattice mismatch between HgCdTe/CdTe and the silicon substrate leads to the formation of dislocations at densities in the mid 106 to low 107 cm-2 range in the epilayers. Such a high dislocation density greatly effects detector device performance quantities such as operability and sensitivity. Hence, the dislocation density should be brought down by at least an order of magnitude by adopting novel in situ and ex situ material processing techniques. In this work, in situ and ex situ thermal <span class="hlt">cycle</span> annealing (<span class="hlt">TCA</span>) methods have been used to decrease dislocation density in CdTe and HgCdTe. During the molecular beam epitaxial (MBE) growth of the CdTe buffer layer, the growth was interrupted and the layer was subjected to an annealing <span class="hlt">cycle</span> within the growth chamber under tellurium overpressure. During the annealing <span class="hlt">cycle</span> the temperature is raised to beyond the growth temperature (290 → 550 °C) and then allowed to cool before resuming growth again. This process was repeated several times during the growth. After growth, a portion of the material was subjected to a dislocation decoration etch in order to count the etch pit density (EPD) which has a direct correspondence with the dislocation density in the crystal. The crystalline quality was also characterized by x-ray diffraction rocking curves and photoluminescence. The in situ <span class="hlt">TCA</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/3362853','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/3362853"><span>Interrelations between random walks on diagrams (graphs) with and without <span class="hlt">cycles</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hill, T L</p> <p>1988-05-01</p> <p>Three topics are discussed. A discrete-state, continuous-time random walk with one or more absorption states can be studied by a presumably new method: some mean properties, including the mean time to absorption, can be found from a modified diagram (graph) in which each absorption state is replaced by a one-way <span class="hlt">cycle</span> back to the starting state. The second problem is a random walk on a diagram (graph) with <span class="hlt">cycles</span>. The walk terminates on completion of the first <span class="hlt">cycle</span>. This walk can be replaced by an equivalent walk on a modified diagram with absorption. This absorption diagram can in turn be replaced by another modified diagram with one-way <span class="hlt">cycles</span> back to the starting state, just as in the first problem. The third problem, important in biophysics, relates to a long-time continuous walk on a diagram with <span class="hlt">cycles</span>. This diagram can be transformed (in two steps) to a modified, more-detailed, diagram with one-way <span class="hlt">cycles</span> only. Thus, the one-way <span class="hlt">cycle</span> <span class="hlt">fluxes</span> of the original diagram can be found from the state probabilities of the modified diagram. These probabilities can themselves be obtained by simple matrix inversion (the probabilities are determined by linear algebraic steady-state equations). Thus, a simple method is now available to find one-way <span class="hlt">cycle</span> <span class="hlt">fluxes</span> exactly (previously Monte Carlo simulation was required to find these <span class="hlt">fluxes</span>, with attendant fluctuations, for diagrams of any complexity). An incidental benefit of the above procedure is that it provides a simple proof of the one-way <span class="hlt">cycle</span> <span class="hlt">flux</span> relation Jn +/- = IIn +/- sigma n/sigma, where n is any <span class="hlt">cycle</span> of the original diagram.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050202033','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050202033"><span>Solar Modulation of Inner Trapped Belt Radiation <span class="hlt">Flux</span> as a Function of Atmospheric Density</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lodhi, M. A. K.</p> <p>2005-01-01</p> <p>No simple algorithm seems to exist for calculating proton <span class="hlt">fluxes</span> and lifetimes in the Earth's inner, trapped radiation belt throughout the solar <span class="hlt">cycle</span>. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in <span class="hlt">Cycle</span> 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton <span class="hlt">fluxes</span> at any time in a given solar <span class="hlt">cycle</span>, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From <span class="hlt">flux</span> and its time integral fluence, one can then approximate dose rate and its time integral dose.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22822147','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22822147"><span>Sulfate burial constraints on the Phanerozoic sulfur <span class="hlt">cycle</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Halevy, Itay; Peters, Shanan E; Fischer, Woodward W</p> <p>2012-07-20</p> <p>The sulfur <span class="hlt">cycle</span> influences the respiration of sedimentary organic matter, the oxidation state of the atmosphere and oceans, and the composition of seawater. However, the factors governing the major sulfur <span class="hlt">fluxes</span> between seawater and sedimentary reservoirs remain incompletely understood. Using macrostratigraphic data, we quantified sulfate evaporite burial <span class="hlt">fluxes</span> through Phanerozoic time. Approximately half of the modern riverine sulfate <span class="hlt">flux</span> comes from weathering of recently deposited evaporites. Rates of sulfate burial are unsteady and linked to changes in the area of marine environments suitable for evaporite formation and preservation. By contrast, rates of pyrite burial and weathering are higher, less variable, and largely balanced, highlighting a greater role of the sulfur <span class="hlt">cycle</span> in regulating atmospheric oxygen.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B41G2054B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B41G2054B"><span>Carbon <span class="hlt">Fluxes</span> and Transport Along the Terrestrial Aquatic Continuum</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butman, D. E.; Kolka, R.; Fennel, K.; Stackpoole, S. M.; Trettin, C.; Windham-Myers, L.</p> <p>2017-12-01</p> <p>Terrestrial wetlands, inland surface waters, tidal wetlands and estuaries, and the coastal ocean are distinct aquatic ecosystems that integrate carbon (C) <span class="hlt">fluxes</span> and processing among the major earth system components: the continents, oceans, and atmosphere. The development of the 2nd State of the Carbon <span class="hlt">Cycle</span> Report (SOCCR2) noted that incorporating the C <span class="hlt">cycle</span> dynamics for these ecosystems was necessary to reconcile some of the gaps associated with the North American C budget. We present major C stocks and <span class="hlt">fluxes</span> for Canada, Mexico and the United States. North America contains nearly 42% of the global terrestrial wetland area. Terrestrial wetlands, defined as soils that are seasonally or permanently inundated or saturated, contain significant C stocks equivalent to 174,000 Tg C in the top 40 cm of soil. While terrestrial wetlands are a C sink of approximately 64 Tg C yr-1, they also emit 21 Tg of CH4 yr-1. Inland waters are defined as lakes, reservoirs, rivers, and streams. Carbon <span class="hlt">fluxes</span>, which include lateral C export to the coast, riverine and lacustrine CO2 emissions, and C burial in lakes and reservoirs are estimated at 507 Tg yr-1. Estuaries and tidal wetlands assimilate C and nutrients from uplands and rivers, and their total C stock is 1,323 Tg C in the top 1 m of soils and sediment. Accounting for soil accretion, lateral C <span class="hlt">flux</span>, and CO2 assimilation and emission, tidal wetlands and estuaries are net sinks with a total <span class="hlt">flux</span> equal to 6 Tg C yr-1. The coastal ocean and sea shelfs, defined as non-estuarine waters within 200 nautical miles (370 km) of the coast, function as net sinks, with the air-sea exchange of CO2 estimated at 150 Tg C yr-1. In total, <span class="hlt">fluxes</span> from these four aquatic ecosystems are equal to a loss of 302 Tg C yr-1. Including these four discrete <span class="hlt">fluxes</span> in this assessment demonstrates the importance of linking hydrology and biogeochemical <span class="hlt">cycling</span> to evaluate the impacts of climate change and human activities on carbon <span class="hlt">fluxes</span> across the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11738484','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11738484"><span>Effects of pentylenetetrazole and glutamate on metabolism of [U-(13)C]glucose in cultured cerebellar granule neurons.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eloqayli, Haytham; Qu, Hong; Unsgård, Geirmund; Sletvold, Olav; Hadidi, Hakam; Sonnewald, Ursula</p> <p>2002-02-01</p> <p>This study was performed to analyze the effects of glutamate and the epileptogenic agent pentylenetetrazole (PTZ) on neuronal glucose metabolism. Cerebellar granule neurons were incubated for 2 h in medium containing 3 mM [U-(13)C]glucose, with and without 0.25 mM glutamate and/or 10 mM PTZ. In the presence of PTZ, decreased glucose consumption with unchanged lactate release was observed, indicating decreased glucose oxidation. PTZ also slowed down tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> activity as evidenced by the decreased amounts of labeled aspartate and [1,2-(13)C]glutamate. When glutamate was present, glucose consumption was also decreased. However, the amount of glutamate, derived from [U-(13)C]glucose via the first turn of the <span class="hlt">TCA</span> <span class="hlt">cycle</span>, was increased. The decreased amount of [1,2-(13)C]glutamate, derived from the second turn in the <span class="hlt">TCA</span> <span class="hlt">cycle</span>, and increased amount of aspartate indicated the dilution of label due to the entrance of unlabeled glutamate into <span class="hlt">TCA</span> <span class="hlt">cycle</span>. In the presence of glutamate plus PTZ, the effect of PTZ was enhanced by glutamate. Labeled alanine was detected only in the presence of glutamate plus PTZ, which indicated that oxaloacetate was a better amino acid acceptor than pyruvate. Furthermore, there was also evidence for intracellular compartmentation of oxaloacetate metabolism. Glutamate and PTZ caused similar metabolic changes, however, via different mechanisms. Glutamate substituted for glucose as energy substrate in the <span class="hlt">TCA</span> <span class="hlt">cycle</span>, whereas, PTZ appeared to decrease mitochondrial activity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1028503','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1028503"><span>Imaging Prostate Cancer (PCa) Phenotype and Evolution</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-10-01</p> <p>inhibit growth of some but not all cell lines. 2. Keywords: Deferiprone, aconitase, metabolism, tricarboxylic acid <span class="hlt">cycle</span> , magnetic resonance 3...TRAMP C2 and MycCaP cell proliferation, migration, and invasiveness. Determine if knockdown of m-acon and Deferiprone inhibit <span class="hlt">TCA</span> <span class="hlt">cycle</span> activity...migration and inhibits <span class="hlt">TCA</span> <span class="hlt">cycle</span> (metabolism). Similarly in vivo (Aim 2), we 6 Fig. 2: Effect of DFP on in vivo growth of MycCaP (left) and TRAMP C2</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BoLMe.tmp..190Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BoLMe.tmp..190Z"><span>Diurnal Variations of the <span class="hlt">Flux</span> Imbalance Over Homogeneous and Heterogeneous Landscapes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Yanzhao; Li, Dan; Liu, Heping; Li, Xin</p> <p>2018-05-01</p> <p>It is well known that the sum of the turbulent sensible and latent heat <span class="hlt">fluxes</span> as measured by the eddy-covariance method is systematically lower than the available energy (i.e., the net radiation minus the ground heat <span class="hlt">flux</span>). We examine the separate and joint effects of diurnal and spatial variations of surface temperature on this <span class="hlt">flux</span> imbalance in a dry convective boundary layer using the Weather Research and Forecasting model. Results show that, over homogeneous surfaces, the <span class="hlt">flux</span> due to turbulent-organized structures is responsible for the imbalance, whereas over heterogeneous surfaces, the <span class="hlt">flux</span> due to mesoscale or secondary circulations is the main contributor to the imbalance. Over homogeneous surfaces, the <span class="hlt">flux</span> imbalance in free convective conditions exhibits a clear diurnal <span class="hlt">cycle</span>, showing that the <span class="hlt">flux</span>-imbalance magnitude slowly decreases during the morning period and rapidly increases during the afternoon period. However, in shear convective conditions, the <span class="hlt">flux</span>-imbalance magnitude is much smaller, but slightly increases with time. The <span class="hlt">flux</span> imbalance over heterogeneous surfaces exhibits a diurnal <span class="hlt">cycle</span> under both free and shear convective conditions, which is similar to that over homogeneous surfaces in free convective conditions, and is also consistent with the general trend in the global observations. The rapid increase in the <span class="hlt">flux</span>-imbalance magnitude during the afternoon period is mainly caused by the afternoon decay of the turbulent kinetic energy (TKE). Interestingly, over heterogeneous surfaces, the <span class="hlt">flux</span> imbalance is linearly related to the TKE and the difference between the potential temperature and surface temperature, ΔT; the larger the TKE and ΔT values, the smaller the <span class="hlt">flux</span>-imbalance magnitude.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2546806','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2546806"><span>CcpN Controls Central Carbon <span class="hlt">Fluxes</span> in Bacillus subtilis▿ ‡</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Tännler, Simon; Fischer, Eliane; Le Coq, Dominique; Doan, Thierry; Jamet, Emmanuel; Sauer, Uwe; Aymerich, Stéphane</p> <p>2008-01-01</p> <p>The transcriptional regulator CcpN of Bacillus subtilis has been recently characterized as a repressor of two gluconeogenic genes, gapB and pckA, and of a small noncoding regulatory RNA, sr1, involved in arginine catabolism. Deletion of ccpN impairs growth on glucose and strongly alters the distribution of intracellular <span class="hlt">fluxes</span>, rerouting the main glucose catabolism from glycolysis to the pentose phosphate (PP) pathway. Using transcriptome analysis, we show that during growth on glucose, gapB and pckA are the only protein-coding genes directly repressed by CcpN. By quantifying intracellular <span class="hlt">fluxes</span> in deletion mutants, we demonstrate that derepression of pckA under glycolytic condition causes the growth defect observed in the ccpN mutant due to extensive futile <span class="hlt">cycling</span> through the pyruvate carboxylase, phosphoenolpyruvate carboxykinase, and pyruvate kinase. Beyond ATP dissipation via this <span class="hlt">cycle</span>, PckA activity causes a drain on tricarboxylic acid <span class="hlt">cycle</span> intermediates, which we show to be the main reason for the reduced growth of a ccpN mutant. The high <span class="hlt">flux</span> through the PP pathway in the ccpN mutant is modulated by the <span class="hlt">flux</span> through the alternative glyceraldehyde-3-phosphate dehydrogenases, GapA and GapB. Strongly increased concentrations of intermediates in upper glycolysis indicate that GapB overexpression causes a metabolic jamming of this pathway and, consequently, increases the relative <span class="hlt">flux</span> through the PP pathway. In contrast, derepression of sr1, the third known target of CcpN, plays only a marginal role in ccpN mutant phenotypes. PMID:18586936</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20180002924&hterms=Remote+sensing&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRemote%2Bsensing','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20180002924&hterms=Remote+sensing&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3DRemote%2Bsensing"><span>On the Ability of Space- Based Passive and Active Remote Sensing Observations of CO2 to Detect <span class="hlt">Flux</span> Perturbations to the Carbon <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Crowell, Sean M. R.; Kawa, S. Randolph; Browell, Edward V.; Hammerling, Dorit M.; Moore, Berrien; Schaefer, Kevin; Doney, Scott C.</p> <p>2018-01-01</p> <p>Space-borne observations of CO2 are vital to gaining understanding of the carbon <span class="hlt">cycle</span> in regions of the world that are difficult to measure directly, such as the tropical terrestrial biosphere, the high northern and southern latitudes, and in developing nations such as China. Measurements from passive instruments such as GOSAT (Greenhouse Gases Observing Satellite) and OCO-2 (Orbiting Carbon Observatory 2), however, are constrained by solar zenith angle limitations as well as sensitivity to the presence of clouds and aerosols. Active measurements such as those in development for the Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) mission show strong potential for making measurements in the high-latitude winter and in cloudy regions. In this work we examine the enhanced <span class="hlt">flux</span> constraint provided by the improved coverage from an active measurement such as ASCENDS. The simulation studies presented here show that with sufficient precision, ASCENDS will detect permafrost thaw and fossil fuel emissions shifts at annual and seasonal time scales, even in the presence of transport errors, representativeness errors, and biogenic <span class="hlt">flux</span> errors. While OCO-2 can detect some of these perturbations at the annual scale, the seasonal sampling provided by ASCENDS provides the stronger constraint. Plain Language Summary: Active and passive remote sensors show the potential to provide unprecedented information on the carbon <span class="hlt">cycle</span>. With the all-season sampling, active remote sensors are more capable of constraining high-latitude emissions. The reduced sensitivity to cloud and aerosol also makes active sensors more capable of providing information in cloudy and polluted scenes with sufficient accuracy. These experiments account for errors that are fundamental to the top-down approach for constraining emissions, and even including these sources of error, we show that satellite remote sensors are critical for understanding the carbon <span class="hlt">cycle</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940023805','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940023805"><span>Extraterrestrial accretion and glacial <span class="hlt">cycles</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Muller, R. A.</p> <p>1994-01-01</p> <p>We propose that the approx. 100-k.y. <span class="hlt">cycle</span> seen in terrestrial glaciation is due to changes in meteor <span class="hlt">flux</span> that come from changes in the Earth's orbit. This model can explain a 70-k.y. 'anomalous' period in climate data and the apparent discrepancy between present extraterrestrial <span class="hlt">fluxes</span> and those in oceanic sediments. It can be tested by measuring Ir densities in sediments and ice during glacials and interglacials.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22365081-effects-meridional-flow-variations-solar-cycles','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22365081-effects-meridional-flow-variations-solar-cycles"><span>Effects of meridional flow variations on solar <span class="hlt">cycles</span> 23 and 24</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Upton, Lisa; Hathaway, David H., E-mail: lisa.a.upton@vanderbilt.edu, E-mail: lar0009@uah.edu, E-mail: david.hathaway@nasa.gov</p> <p>2014-09-10</p> <p>The faster meridional flow that preceded the solar <span class="hlt">cycle</span> 23/24 minimum is thought to have led to weaker polar field strengths, producing the extended solar minimum and the unusually weak <span class="hlt">cycle</span> 24. To determine the impact of meridional flow variations on the sunspot <span class="hlt">cycle</span>, we have simulated the Sun's surface magnetic field evolution with our newly developed surface <span class="hlt">flux</span> transport model. We investigate three different cases: a constant average meridional flow, the observed time-varying meridional flow, and a time-varying meridional flow in which the observed variations from the average have been doubled. Comparison of these simulations shows that the variationsmore » in the meridional flow over <span class="hlt">cycle</span> 23 have a significant impact (∼20%) on the polar fields. However, the variations produced polar fields that were stronger than they would have been otherwise. We propose that the primary cause of the extended <span class="hlt">cycle</span> 23/24 minimum and weak <span class="hlt">cycle</span> 24 was the weakness of <span class="hlt">cycle</span> 23 itself—with fewer sunspots, there was insufficient <span class="hlt">flux</span> to build a big <span class="hlt">cycle</span>. We also find that any polar counter-cells in the meridional flow (equatorward flow at high latitudes) produce <span class="hlt">flux</span> concentrations at mid-to-high latitudes that are not consistent with observations.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27220007','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27220007"><span>Interaction of light quality and fertility on biomass, shoot pigmentation and xanthophyll <span class="hlt">cycle</span> <span class="hlt">flux</span> in Chinese kale.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kopsell, Dean A; Sams, Carl E; Morrow, Robert C</p> <p>2017-02-01</p> <p>Nutritionally important carotenoids in 21-day-old brassica microgreens increase following short and long-term exposure to narrow-band wavelengths from light-emitting diodes (LED). The present study aimed to measure the impact of: (1) fluorescent/incandescent light and different percentages of blue/red LED light and (2) different levels of nutrient fertility on biomass and pigment concentrations in 30-day-old 'Green Lance' Chinese kale (Brassica oleracea var. alboglabra). Kale plants were exposed to four light treatments and two fertility levels and were harvested 30 days after seeding and analyzed for nutritionally important shoot pigments. Kale under the fluorescent/incandescent light treatment had a significantly higher shoot fresh and dry mass. The shoot tissue concentrations of most pigment were significantly higher under blue/red LED light treatments. The higher fertility level resulted in higher concentrations for most pigments. Interestingly, the pool of xanthophyll <span class="hlt">cycle</span> pigments and de-epoxidized xanthophylls was higher under all LED treatments. The results obtained in the present study support previous data demonstrating the stimulation of nutritionally important shoot tissue pigment concentrations following exposure to sole source blue/red LEDs compared to traditional lighting. Xanthophyll <span class="hlt">cycle</span> <span class="hlt">flux</span> was impacted by LEDs and this may support the role of zeaxanthin in blue light perception in leafy specialty crops. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1361528-predicting-carbon-dioxide-energy-fluxes-across-global-fluxnet-sites-regression-algorithms','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1361528-predicting-carbon-dioxide-energy-fluxes-across-global-fluxnet-sites-regression-algorithms"><span>Predicting carbon dioxide and energy <span class="hlt">fluxes</span> across global FLUXNET sites with regression algorithms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Tramontana, Gianluca; Jung, Martin; Schwalm, Christopher R.; ...</p> <p>2016-07-29</p> <p>Spatio-temporal fields of land–atmosphere <span class="hlt">fluxes</span> derived from data-driven models can complement simulations by process-based land surface models. While a number of strategies for empirical models with eddy-covariance <span class="hlt">flux</span> data have been applied, a systematic intercomparison of these methods has been missing so far. In this study, we performed a cross-validation experiment for predicting carbon dioxide, latent heat, sensible heat and net radiation <span class="hlt">fluxes</span> across different ecosystem types with 11 machine learning (ML) methods from four different classes (kernel methods, neural networks, tree methods, and regression splines). We applied two complementary setups: (1) 8-day average <span class="hlt">fluxes</span> based on remotely sensed data andmore » (2) daily mean <span class="hlt">fluxes</span> based on meteorological data and a mean seasonal <span class="hlt">cycle</span> of remotely sensed variables. The patterns of predictions from different ML and experimental setups were highly consistent. There were systematic differences in performance among the <span class="hlt">fluxes</span>, with the following ascending order: net ecosystem exchange ( R 2 < 0.5), ecosystem respiration ( R 2 > 0.6), gross primary production ( R 2> 0.7), latent heat ( R 2 > 0.7), sensible heat ( R 2 > 0.7), and net radiation ( R 2 > 0.8). The ML methods predicted the across-site variability and the mean seasonal <span class="hlt">cycle</span> of the observed <span class="hlt">fluxes</span> very well ( R 2 > 0.7), while the 8-day deviations from the mean seasonal <span class="hlt">cycle</span> were not well predicted ( R 2 < 0.5). <span class="hlt">Fluxes</span> were better predicted at forested and temperate climate sites than at sites in extreme climates or less represented by training data (e.g., the tropics). Finally, the evaluated large ensemble of ML-based models will be the basis of new global <span class="hlt">flux</span> products.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1361528','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1361528"><span>Predicting carbon dioxide and energy <span class="hlt">fluxes</span> across global FLUXNET sites with regression algorithms</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Tramontana, Gianluca; Jung, Martin; Schwalm, Christopher R.</p> <p></p> <p>Spatio-temporal fields of land–atmosphere <span class="hlt">fluxes</span> derived from data-driven models can complement simulations by process-based land surface models. While a number of strategies for empirical models with eddy-covariance <span class="hlt">flux</span> data have been applied, a systematic intercomparison of these methods has been missing so far. In this study, we performed a cross-validation experiment for predicting carbon dioxide, latent heat, sensible heat and net radiation <span class="hlt">fluxes</span> across different ecosystem types with 11 machine learning (ML) methods from four different classes (kernel methods, neural networks, tree methods, and regression splines). We applied two complementary setups: (1) 8-day average <span class="hlt">fluxes</span> based on remotely sensed data andmore » (2) daily mean <span class="hlt">fluxes</span> based on meteorological data and a mean seasonal <span class="hlt">cycle</span> of remotely sensed variables. The patterns of predictions from different ML and experimental setups were highly consistent. There were systematic differences in performance among the <span class="hlt">fluxes</span>, with the following ascending order: net ecosystem exchange ( R 2 < 0.5), ecosystem respiration ( R 2 > 0.6), gross primary production ( R 2> 0.7), latent heat ( R 2 > 0.7), sensible heat ( R 2 > 0.7), and net radiation ( R 2 > 0.8). The ML methods predicted the across-site variability and the mean seasonal <span class="hlt">cycle</span> of the observed <span class="hlt">fluxes</span> very well ( R 2 > 0.7), while the 8-day deviations from the mean seasonal <span class="hlt">cycle</span> were not well predicted ( R 2 < 0.5). <span class="hlt">Fluxes</span> were better predicted at forested and temperate climate sites than at sites in extreme climates or less represented by training data (e.g., the tropics). Finally, the evaluated large ensemble of ML-based models will be the basis of new global <span class="hlt">flux</span> products.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=275782','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=275782"><span>Comparison of buried soil sensors, surface chambers and above ground measurements of carbon dioxide <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Soil carbon dioxide (CO2) <span class="hlt">flux</span> is an important component of the terrestrial carbon <span class="hlt">cycle</span>. Accurate measurements of soil CO2 <span class="hlt">flux</span> aids determinations of carbon budgets. In this study, we investigated soil CO2 <span class="hlt">fluxes</span> with time and depth and above ground CO2 <span class="hlt">fluxes</span> in a bare field. CO2 concentrations w...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH51C2513A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH51C2513A"><span>Periodicities observed on solar <span class="hlt">flux</span> index (F10.7) during geomagnetic disturbances</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adhikari, B.; Narayan, C.; Chhatkuli, D. N.</p> <p>2017-12-01</p> <p>Solar activities change within the period of 11 years. Sometimes the greatest event occurs in the period of solar maxima and the lowest activity occurs in the period of solar minimum. During the time period of solar activity sunspots number will vary. A 10.7 cm solar <span class="hlt">flux</span> measurement is a determination of the strength of solar radio emission. The solar <span class="hlt">flux</span> index is more often used for the prediction and monitoring of the solar activity. This study mainly focused on the variation on solar <span class="hlt">flux</span> index and amount of electromagnetic wave in the atmosphere. Both seasonal and yearly variation on solar F10.7 index. We also analyzed the dataset obatained from riometer.Both instruments show seasonal and yearly variations. We also observed the solar <span class="hlt">cycle</span> dependence on solar <span class="hlt">flux</span> index and found a strong dependence on solar activity. Results also show that solar intensities higher during the rising phase of solar <span class="hlt">cycle</span>. We also observed periodicities on solar <span class="hlt">flux</span> index using wavelet analysis. Through this analysis, it was found that the power intensities of solar <span class="hlt">flux</span> index show a high spectral variability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39..458D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39..458D"><span>The solar dynamo and prediction of sunspot <span class="hlt">cycles</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dikpati, Mausumi</p> <p>2012-07-01</p> <p>Much progress has been made in understanding the solar dynamo since Parker first developed the concepts of dynamo waves and magnetic buoyancy around 1955, and the German school first formulated the solar dynamo using the mean-field formalism. The essential ingredients of these mean-field dynamos are turbulent magnetic diffusivity, a source of lifting of <span class="hlt">flux</span>, or 'alpha-effect', and differential rotation. With the advent of helioseismic and other observations at the Sun's photosphere and interior, as well as theoretical understanding of solar interior dynamics, solar dynamo models have evolved both in the realm of mean-field and beyond mean-field models. After briefly discussing the status of these models, I will focus on a class of mean-field model, called <span class="hlt">flux</span>-transport dynamos, which include meridional circulation as an essential additional ingredient. <span class="hlt">Flux</span>-transport dynamos have been successful in simulating many global solar <span class="hlt">cycle</span> features, and have reached the stage that they can be used for making solar <span class="hlt">cycle</span> predictions. Meridional circulation works in these models like a conveyor-belt, carrying a memory of the magnetic fields from 5 to 20 years back in past. The lower is the magnetic diffusivity, the longer is the model's memory. In the terrestrial system, the great-ocean conveyor-belt in oceanic models and Hadley, polar and Ferrel circulation cells in the troposphere, carry signatures from the past climatological events and influence the determination of future events. Analogously, the memory provided by the Sun's meridional circulation creates the potential for <span class="hlt">flux</span>-transport dynamos to predict future solar <span class="hlt">cycle</span> properties. Various groups in the world have built <span class="hlt">flux</span>-transport dynamo-based predictive tools, which nudge the Sun's surface magnetic data and integrated forward in time to forecast the amplitude of the currently ascending <span class="hlt">cycle</span> 24. Due to different initial conditions and different choices of unknown model-ingredients, predictions can vary; so</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.B24A0323L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.B24A0323L"><span>Estimates of Gelatinous Zooplankton Carbon <span class="hlt">Flux</span> in the Global Oceans</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luo, J. Y.; Condon, R.; Cowen, R. K.</p> <p>2016-02-01</p> <p>Gelatinous zooplankton (GZ), which include the cnidarians, ctenophores, and pelagic tunicates, are a common feature of marine ecosystems worldwide, but their contribution to global biogeochemical <span class="hlt">fluxes</span> has never been assessed. We constructed a carbon-<span class="hlt">cycle</span> model with a single, annual time-step and resolved to a 5° spatial grid for the three major GZ groups in order to evaluate the GZ-mediated carbon <span class="hlt">fluxes</span> and export to depth. Biomass inputs (totaling 0.149 Pg C) were based off of Lucas et al. (2014) and updated using the JeDI database (Condon et al. 2015). From the upper ocean, biomass export <span class="hlt">flux</span> from cnidarians, ctenophores, and tunicates totaled 2.96 ± 2.82 Pg C y-1, though only 0.199 ± 0.023 Pg C y-1 of GZ carbon were transferred to upper trophic levels, roughly amounting to one-quarter of all mesozooplankton production <span class="hlt">flux</span>. In contrast, GZ <span class="hlt">fluxes</span> to DOC only comprised ca. 2% of labile DOC <span class="hlt">flux</span>. Egestion <span class="hlt">flux</span> from the upper ocean totaled 2.56 ± 3.35 Pg C y-1, with over 80% being fast-sinking tunicate fecal pellets. Due to fast sinking rates of carcasses and fecal pellets, 26% of all C export from the upper ocean reached the seafloor, such that GZ fecal matter is estimated to comprise between 20-30% of global POC surface export and 11-30% of POC seafloor deposition. Finally, results from sensitivity analyses showed no increase in cnidarian and ctenophore export <span class="hlt">fluxes</span> with increased temperature and jelly biomass, though tunicate export <span class="hlt">fluxes</span> showed some increase with both temperature and biomass. These results suggest that current estimates of global POC <span class="hlt">flux</span> from the surface oceans, which range between 8.6 - 12.9 Pg C y-1, may be underestimated by as much as 20 - 25%, implying a definite need to incorporate GZ mediated <span class="hlt">flux</span> in estimating the biological pump transfer efficiency. Our study represents the first effort to quantify the role of gelatinous zooplankton in the global marine carbon <span class="hlt">cycle</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28324854','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28324854"><span>Accounting for urban biogenic <span class="hlt">fluxes</span> in regional carbon budgets.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hardiman, Brady S; Wang, Jonathan A; Hutyra, Lucy R; Gately, Conor K; Getson, Jackie M; Friedl, Mark A</p> <p>2017-08-15</p> <p>Many ecosystem models incorrectly treat urban areas as devoid of vegetation and biogenic carbon (C) <span class="hlt">fluxes</span>. We sought to improve estimates of urban biomass and biogenic C <span class="hlt">fluxes</span> using existing, nationally available data products. We characterized biogenic influence on urban C <span class="hlt">cycling</span> throughout Massachusetts, USA using an ecosystem model that integrates improved representation of urban vegetation, growing conditions associated with urban heat island (UHI), and altered urban phenology. Boston's biomass density is 1/4 that of rural forests, however 87% of Massachusetts' urban landscape is vegetated. Model results suggest that, kilogram-for-kilogram, urban vegetation <span class="hlt">cycles</span> C twice as fast as rural forests. Urban vegetation releases (R E ) and absorbs (GEE) the equivalent of 11 and 14%, respectively, of anthropogenic emissions in the most urban portions of the state. While urban vegetation in Massachusetts fully sequesters anthropogenic emissions from smaller cities in the region, Boston's UHI reduces annual C storage by >20% such that vegetation offsets only 2% of anthropogenic emissions. Asynchrony between temporal patterns of biogenic and anthropogenic C <span class="hlt">fluxes</span> further constrains the emissions mitigation potential of urban vegetation. However, neglecting to account for biogenic C <span class="hlt">fluxes</span> in cities can impair efforts to accurately monitor, report, verify, and reduce anthropogenic emissions. Copyright © 2017 Elsevier B.V. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27830359','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27830359"><span>High-density natural luffa sponge as anaerobic microorganisms carrier for degrading 1,1,1-<span class="hlt">TCA</span> in groundwater.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Wenbing; Wu, Yanqing; Zhang, Chi</p> <p>2017-03-01</p> <p>Anaerobic microorganisms were applied to degrade organic contaminants in groundwater with permeable reactive barriers (PRBs). However, anaerobic microorganisms need to select optimal immobilizing material as carrier. The potential of high-density natural luffa sponge (HDLS) (a new variety of luffa) for the immobilization and protection of anaerobic microorganisms was investigated. The HDLS has a dense structure composed of a complicated interwoven fibrous network. Therefore, the abrasion rate of HDLS (0.0068 g s -1 ) was the smallest among the four carriers [HDLS, ordinary natural luffa sponge (OLS), polyurethane sponge (PS), and gel carrier AQUAPOROUSGEL (APG)]. The results suggest that it also had the greatest water retention (10.26 H 2 O-g dry carrier-g -1 ) and SS retention (0.21 g dry carrier-g -1 ). In comparison to well-established commercialized gel carrier APG, HDLS was of much better mechanical strength, hydrophilicity and stability. Microbial-immobilized HDLS also had the best performance for the remediation of 1,1,1-<span class="hlt">TCA</span> simulated groundwater. Analysis of the clone libraries from microorganism-immobilized HDLS showed the HDLS could protect microorganisms from the toxicity of 1,1,1-<span class="hlt">TCA</span> and maintain the stability of microbial community diversity. The mechanism of HDLS immobilizing and protecting microorganisms was proposed as follows. The HDLS had a micron-scale honeycomb structure (30-40 μm) and an irregular ravine structure (4-20 μm), which facilitate the immobilization of anaerobic microorganisms and protect the anaerobic microorganisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981ftdf.rept.....A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981ftdf.rept.....A"><span><span class="hlt">Flux</span>-trapping during the formation of field-reversed configurations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armstrong, W. T.; Harding, D. G.; Crawford, E. A.; Hoffman, A. L.</p> <p>1981-10-01</p> <p>Optimized trapping of bias <span class="hlt">flux</span> during the early formation phases of a Field Reversed Configuration was studied experimentally on the field reversed theta pinch TRX-1. An annular z-pinch preionizer was employed to permit ionization at high values of initial reverse bias <span class="hlt">flux</span>. Octopole barrier fields are pulsed during field reversal to minimize plasma/wall contact and associated loss of reverse <span class="hlt">flux</span>. Also, second half <span class="hlt">cycle</span> operation was examined in obtaining very high values of reverse <span class="hlt">flux</span>. <span class="hlt">Flux</span> loss is generally observed to be governed by resistive diffusion through a current sheath at the plasma boundary, rather than <span class="hlt">flux</span> convection to the plasma boundary. Trapped reverse <span class="hlt">flux</span> at the time of field reversal, as well as after the radial implosion, is observed to increase with the applied bias field. This increase is greatest, and in fact nearly linear with bias field, when barrier fields are employed. Barrier fields also appear to broaden the current sheath, which results in some <span class="hlt">flux</span> loss and a less dynamic radial implosion. A general model and one dimensional simulation of <span class="hlt">flux</span> loss is described and correlated with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26919319','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26919319"><span>Parasite infection alters nitrogen <span class="hlt">cycling</span> at the ecosystem scale.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mischler, John; Johnson, Pieter T J; McKenzie, Valerie J; Townsend, Alan R</p> <p>2016-05-01</p> <p>Despite growing evidence that parasites often alter nutrient flows through their hosts and can comprise a substantial amount of biomass in many systems, whether endemic parasites influence ecosystem nutrient <span class="hlt">cycling</span>, and which nutrient pathways may be important, remains conjectural. A framework to evaluate how endemic parasites alter nutrient <span class="hlt">cycling</span> across varied ecosystems requires an understanding of the following: (i) parasite effects on host nutrient excretion; (ii) ecosystem nutrient limitation; (iii) effects of parasite abundance, host density, host functional role and host excretion rate on nutrient flows; and (iv) how this infection-induced nutrient <span class="hlt">flux</span> compares to other pools and <span class="hlt">fluxes</span>. Pathogens that significantly increase the availability of a limiting nutrient within an ecosystem should produce a measurable ecosystem-scale response. Here, we combined field-derived estimates of trematode parasite infections in aquatic snails with measurements of snail excretion and tissue stoichiometry to show that parasites are capable of altering nutrient excretion in their intermediate host snails (dominant grazers). We integrated laboratory measurements of host nitrogen excretion with field-based estimates of infection in an ecosystem model and compared these <span class="hlt">fluxes</span> to other pools and <span class="hlt">fluxes</span> of nitrogen as measured in the field. Eighteen nitrogen-limited ponds were examined to determine whether infection had a measurable effect on ecosystem-scale nitrogen <span class="hlt">cycling</span>. Because of their low nitrogen content and high demand for host carbon, parasites accelerated the rate at which infected hosts excreted nitrogen to the water column in a dose-response manner, thereby shifting nutrient stoichiometry and availability at the ecosystem scale. Infection-enhanced <span class="hlt">fluxes</span> of dissolved inorganic nitrogen were similar to other commonly important environmental sources of bioavailable nitrogen to the system. Additional field measurements within nitrogen-limited ponds indicated that</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1985tehs.nasa...51A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1985tehs.nasa...51A"><span>Development of heat <span class="hlt">flux</span> sensors for turbine airfoils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Atkinson, William H.; Cyr, Marcia A.; Strange, Richard R.</p> <p>1985-10-01</p> <p>The objectives of this program are to develop heat <span class="hlt">flux</span> sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat <span class="hlt">flux</span> sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal <span class="hlt">cycle</span> and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat <span class="hlt">flux</span> measurements produced by these sensors. The results of the cylinder in cross flow tests are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880001761','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880001761"><span>Development of heat <span class="hlt">flux</span> sensors for turbine airfoils</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Atkinson, William H.; Cyr, Marcia A.; Strange, Richard R.</p> <p>1985-01-01</p> <p>The objectives of this program are to develop heat <span class="hlt">flux</span> sensors suitable for installation in hot section airfoils of advanced aircraft turbine engines and to experimentally verify the operation of these heat <span class="hlt">flux</span> sensors in a cylinder in a cross flow experiment. Embedded thermocouple and Gardon gauge sensors were developed and fabricated into both blades and vanes. These were then calibrated using a quartz lamp bank heat source and finally subjected to thermal <span class="hlt">cycle</span> and thermal soak testing. These sensors were also fabricated into cylindrical test pieces and tested in a burner exhaust to verify heat <span class="hlt">flux</span> measurements produced by these sensors. The results of the cylinder in cross flow tests are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=80840&Lab=NRMRL&keyword=nitrogen+AND+balance&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50','EPA-EIMS'); return false;" href="https://cfpub.epa.gov/si/si_public_record_report.cfm?dirEntryId=80840&Lab=NRMRL&keyword=nitrogen+AND+balance&actType=&TIMSType=+&TIMSSubTypeID=&DEID=&epaNumber=&ntisID=&archiveStatus=Both&ombCat=Any&dateBeginCreated=&dateEndCreated=&dateBeginPublishedPresented=&dateEndPublishedPresented=&dateBeginUpdated=&dateEndUpdated=&dateBeginCompleted=&dateEndCompleted=&personID=&role=Any&journalID=&publisherID=&sortBy=revisionDate&count=50"><span>MODELING SEDIMENT-NUTRIENT <span class="hlt">FLUX</span> AND SEDIMENT OXYGEN DEMAND</span></a></p> <p><a target="_blank" href="http://oaspub.epa.gov/eims/query.page">EPA Science Inventory</a></p> <p></p> <p></p> <p>Depositional <span class="hlt">flux</span> of particulate organic matter in bottom sediments affects nutrients <span class="hlt">cycling</span> at the sediment-water interface and consumes oxygen from the overlying water in streams, lakes, and estuaries. This project deals with analytical modeling of nitrogen and carbon producti...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B51I1941B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B51I1941B"><span>A Spatial-Temporal Comparison of Lake Mendota CO2 <span class="hlt">Fluxes</span> and Collection Methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Baldocchi, A. K.; Reed, D. E.; Desai, A. R.; Loken, L. C.; Schramm, P.; Stanley, E. H.</p> <p>2017-12-01</p> <p>Monitoring of carbon <span class="hlt">fluxes</span> at the lake/atmosphere interface can help us determine baselines from which to understand responses in both space and time that may result from our warming climate or increasing nutrient inputs. Since recent research has shown lakes to be hotspots of global carbon <span class="hlt">cycling</span>, it is important to quantify carbon sink and source dynamics as well as to verify observations between multiple methods in the context of long-term data collection efforts. Here we evaluate a new method for measuring space and time variation in CO2 <span class="hlt">fluxes</span> based on novel speedboat-based collection method of aquatic greenhouse gas concentrations and a <span class="hlt">flux</span> computation and interpolation algorithm. Two-hundred and forty-nine consecutive days of spatial <span class="hlt">flux</span> maps over the 2016 open ice period were compared to ongoing eddy covariance tower <span class="hlt">flux</span> measurements on the shore of Lake Mendota, Wisconsin US using a <span class="hlt">flux</span> footprint analysis. Spatial and temporal alignments of the <span class="hlt">fluxes</span> from these two observational datasets revealed both similar trends from daily to seasonal timescales as well as biases between methods. For example, throughout the Spring carbon <span class="hlt">fluxes</span> showed strong correlation although off by an order of magnitude. Isolating physical patterns of agreement between the two methods of the lake/atmosphere CO2 <span class="hlt">fluxes</span> allows us to pinpoint where biology and physical drivers contribute to the global carbon <span class="hlt">cycle</span> and help improve modelling of lakes and utilize lakes as leading indicators of climate change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EOSTr..93..203R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EOSTr..93..203R"><span>A Brazilian network of carbon <span class="hlt">flux</span> stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roberti, Débora R.; Acevedo, Otávio C.; Moraes, Osvaldo L. L.</p> <p>2012-05-01</p> <p>First Brasflux Workshop; Santa Maria, Rio Grande do Sul, Brazil, 14-15 November 2011 Last November, 33 researchers participated in a workshop to establish Brasflux, the Brazilian network of carbon <span class="hlt">flux</span> stations, with the objective of integrating previous efforts and planning for the future. Among the participants were those leading ongoing <span class="hlt">flux</span> observation projects and others planning to establish <span class="hlt">flux</span> stations in the near future. International scientists also participated to share the experiences gained with other networks. The need to properly characterize terrestrial ecosystems for their roles in the global carbon, water, and energy budgets has motivated the implementation of hundreds of micrometeorological research sites throughout the world in recent years. The eddy covariance (EC) technique for turbulent <span class="hlt">flux</span> determination is the preferred method to provide integral information on ecosystematmosphere exchanges. Integrating the observations regionally and globally has proven to be an effective approach to maximizing the usefulness of this technique for carbon <span class="hlt">cycle</span> studies at multiple scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29876449','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29876449"><span><span class="hlt">TCA</span> precipitation and ethanol/HCl single-step purification evaluation: One-dimensional gel electrophoresis, bradford assays, spectrofluorometry and Raman spectroscopy data on HSA, Rnase, lysozyme - Mascots and Skyline data.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Eddhif, Balkis; Guignard, Nadia; Batonneau, Yann; Clarhaut, Jonathan; Papot, Sébastien; Geffroy-Rodier, Claude; Poinot, Pauline</p> <p>2018-04-01</p> <p>The data presented here are related to the research paper entitled "Study of a Novel Agent for <span class="hlt">TCA</span> Precipitated Proteins Washing - Comprehensive Insights into the Role of Ethanol/HCl on Molten Globule State by Multi-Spectroscopic Analyses" (Eddhif et al., submitted for publication) [1]. The suitability of ethanol/HCl for the washing of <span class="hlt">TCA</span>-precipitated proteins was first investigated on standard solution of HSA, cellulase, ribonuclease and lysozyme. Recoveries were assessed by one-dimensional gel electrophoresis, Bradford assays and UPLC-HRMS. The mechanistic that triggers protein conformational changes at each purification stage was then investigated by Raman spectroscopy and spectrofluorometry. Finally, the efficiency of the method was evaluated on three different complex samples (mouse liver, river biofilm, loamy soil surface). Proteins profiling was assessed by gel electrophoresis and by UPLC-HRMS.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993JGR....9810211R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993JGR....9810211R"><span>Determination of ocean surface heat <span class="hlt">fluxes</span> by a variational method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Roquet, H.; Planton, S.; Gaspar, P.</p> <p>1993-06-01</p> <p>A new technique of determination of the "nonsolar" heat <span class="hlt">flux</span> (sum of the latent, sensible, and net infrared <span class="hlt">fluxes</span>) at the ocean surface is proposed. It applies when oceanic advection remains weak and thus relies on a one-dimensional modeling approach. It is based on a variational data assimilation scheme using the adjoint equation formalism. This allows to take advantage of all observed data with their error estimates. Results from experiments performed with station Papa (Gulf of Alaska) and Long-Term Upper Ocean Study (LOTUS, Sargasso Sea) data sets are discussed. The temperature profiles assimilation allows the one-dimensional model to reproduce correctly the temperature evolution at the surface and under the oceanic mixed layer at the two sites. The retrieved <span class="hlt">fluxes</span> are compared to the <span class="hlt">fluxes</span> calculated through classical empirical formulae. The diurnal dependence of the <span class="hlt">fluxes</span> at the LOTUS site is particularly investigated. The results are also compared with those obtained using a simpler technique based on an iterative shooting method and allowing the assimilation of the only sea surface temperature. This second comparison reveals that the variability of the retrieved <span class="hlt">fluxes</span> is damped when temperature in the inner ocean are assimilated. This is the case for the diurnal <span class="hlt">cycle</span> at the LOTUS mooring. When the available current data at this site are assimilated, the diurnal variability of the retrieved <span class="hlt">fluxes</span> is further decreased. This points out a model discrepancy in the representation of mixing processes associated to internal wave activity. The remaining part of the diurnal <span class="hlt">cycle</span> is significant and could be due to a direct effect of air-sea temperature difference.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017A%26A...607A..76W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017A%26A...607A..76W"><span>Parameter optimization for surface <span class="hlt">flux</span> transport models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Whitbread, T.; Yeates, A. R.; Muñoz-Jaramillo, A.; Petrie, G. J. D.</p> <p>2017-11-01</p> <p>Accurate prediction of solar activity calls for precise calibration of solar <span class="hlt">cycle</span> models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies for what occurs in the interior and provide source terms for coronal models. We use a genetic algorithm to optimize surface <span class="hlt">flux</span> transport models using National Solar Observatory (NSO) magnetogram data for Solar <span class="hlt">Cycle</span> 23. This is applied to both a 1D model that inserts new magnetic <span class="hlt">flux</span> in the form of idealized bipolar magnetic regions, and also to a 2D model that assimilates specific shapes of real active regions. The genetic algorithm searches for parameter sets (meridional flow speed and profile, supergranular diffusivity, initial magnetic field, and radial decay time) that produce the best fit between observed and simulated butterfly diagrams, weighted by a latitude-dependent error structure which reflects uncertainty in observations. Due to the easily adaptable nature of the 2D model, the optimization process is repeated for <span class="hlt">Cycles</span> 21, 22, and 24 in order to analyse <span class="hlt">cycle-to-cycle</span> variation of the optimal solution. We find that the ranges and optimal solutions for the various regimes are in reasonable agreement with results from the literature, both theoretical and observational. The optimal meridional flow profiles for each regime are almost entirely within observational bounds determined by magnetic feature tracking, with the 2D model being able to accommodate the mean observed profile more successfully. Differences between models appear to be important in deciding values for the diffusive and decay terms. In like fashion, differences in the behaviours of different solar <span class="hlt">cycles</span> lead to contrasts in parameters defining the meridional flow and initial field strength.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060002563','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060002563"><span>Anticipated Improvements to Net Surface Freshwater <span class="hlt">Fluxes</span> from GPM</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Eric A.</p> <p>2005-01-01</p> <p>Evaporation and precipitation over the oceans play very important roles in the global water <span class="hlt">cycle</span>, upper-ocean heat budget, ocean dynamics, and coupled ocean-atmosphere dynamics. In the conventional representation of the terrestrial water <span class="hlt">cycle</span>, the assumed role of the oceans is to act as near-infinite reservoirs of water with the main drivers of the water <span class="hlt">cycle</span> being land- atmosphere interactions in which excess precipitation (P) over evaporation (E) is returned to the oceans as surface runoff and baseflow. Whereas this perspective is valid for short space and time scales -- fundamental principles, available observed estimates, and results from models indicate that the oceans play a far more important role in the large-scale water <span class="hlt">cycle</span> at seasonal and longer timescales. Approximately 70-80% of the total global evaporation and precipitation occurs over oceans. Moreover, latent heat release into the atmosphere over the oceans is the major heat source driving global atmospheric circulations, with the moisture transported by circulations from oceans to continents being the major source of water precipitating over land. Notably, the major impediment in understanding and modeling the oceans role in the global water <span class="hlt">cycle</span> is the lack of reliable net surface freshwater <span class="hlt">flux</span> estimates (E - P <span class="hlt">fluxes</span>) at the salient spatial and temporal resolutions, i.e., consistent coupled weekly to monthly E - P gridded datasets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4044858','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4044858"><span>A Diel <span class="hlt">Flux</span> Balance Model Captures Interactions between Light and Dark Metabolism during Day-Night <span class="hlt">Cycles</span> in C3 and Crassulacean Acid Metabolism Leaves1[C][W][OPEN</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Cheung, C.Y. Maurice; Poolman, Mark G.; Fell, David. A.; Ratcliffe, R. George; Sweetlove, Lee J.</p> <p>2014-01-01</p> <p>Although leaves have to accommodate markedly different metabolic <span class="hlt">flux</span> patterns in the light and the dark, models of leaf metabolism based on <span class="hlt">flux</span>-balance analysis (FBA) have so far been confined to consideration of the network under continuous light. An FBA framework is presented that solves the two phases of the diel <span class="hlt">cycle</span> as a single optimization problem and, thus, provides a more representative model of leaf metabolism. The requirement to support continued export of sugar and amino acids from the leaf during the night and to meet overnight cellular maintenance costs forces the model to set aside stores of both carbon and nitrogen during the day. With only minimal constraints, the model successfully captures many of the known features of C3 leaf metabolism, including the recently discovered role of citrate synthesis and accumulation in the night as a precursor for the provision of carbon skeletons for amino acid synthesis during the day. The diel FBA model can be applied to other temporal separations, such as that which occurs in Crassulacean acid metabolism (CAM) photosynthesis, allowing a system-level analysis of the energetics of CAM. The diel model predicts that there is no overall energetic advantage to CAM, despite the potential for suppression of photorespiration through CO2 concentration. Moreover, any savings in enzyme machinery costs through suppression of photorespiration are likely to be offset by the higher <span class="hlt">flux</span> demand of the CAM <span class="hlt">cycle</span>. It is concluded that energetic or nitrogen use considerations are unlikely to be evolutionary drivers for CAM photosynthesis. PMID:24596328</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25636903','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25636903"><span>Adaptation of oxidative phosphorylation to photoperiod-induced seasonal metabolic states in migratory songbirds.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trivedi, Amit Kumar; Malik, Shalie; Rani, Sangeeta; Kumar, Vinod</p> <p>2015-06-01</p> <p>Eukaryotic cells produce chemical energy in the form of ATP by oxidative phosphorylation of metabolic fuels via a series of enzyme mediated biochemical reactions. We propose that the rates of these reactions are altered, as per energy needs of the seasonal metabolic states in avian migrants. To investigate this, blackheaded buntings were photoperiodically induced with non-migratory, premigratory, migratory and post-migratory phenotypes. High plasma levels of free fatty acids, citrate (an intermediate that begins the <span class="hlt">TCA</span> <span class="hlt">cycle</span>) and malate dehydrogenase (mdh, an enzyme involved at the end of the <span class="hlt">TCA</span> <span class="hlt">cycle</span>) confirmed increased availability of metabolic reserves and substrates to the <span class="hlt">TCA</span> <span class="hlt">cycle</span> during the premigratory and migratory states, respectively. Further, daily expression pattern of genes coding for enzymes involved in the oxidative decarboxylation of pyruvate to acetyl-CoA (pdc and pdk) and oxidative phosphorylation in the <span class="hlt">TCA</span> <span class="hlt">cycle</span> (cs, odgh, sdhd and mdh) was monitored in the hypothalamus and liver. Reciprocal relationship between pdc and pdk expressions conformed with the altered requirements of acetyl-CoA for the <span class="hlt">TCA</span> <span class="hlt">cycle</span> in different metabolic states. Except for pdk, all genes had a daily expression pattern, with high mRNA expression during the day in the premigratory/migratory phenotypes, and at night (cs, odhg, sdhd and mdh) in the nonmigratory phenotype. Differences in mRNA expression patterns of pdc, sdhd and mdh, but not of pdk, cs and odgh, between the hypothalamus and liver indicated a tissue dependent metabolism in buntings. These results suggest the adaptation of oxidative phosphorylation pathway(s) at gene levels to the seasonal alternations in metabolism in migratory songbirds. Copyright © 2015 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=101993','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=101993"><span>Catabolism of α-Ketoglutarate by a sucA Mutant of Bradyrhizobium japonicum: Evidence for an Alternative Tricarboxylic Acid <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Green, Laura S.; Li, Youzhong; Emerich, David W.; Bergersen, Fraser J.; Day, David A.</p> <p>2000-01-01</p> <p>A complete tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> is generally considered necessary for energy production from the dicarboxylic acid substrates malate, succinate, and fumarate. However, a Bradyrhizobium japonicum sucA mutant that is missing α-ketoglutarate dehydrogenase is able to grow on malate as its sole source of carbon. This mutant also fixes nitrogen in symbiosis with soybean, where dicarboxylic acids are its principal carbon substrate. Using a flow chamber system to make direct measurements of oxygen consumption and ammonium excretion, we confirmed that bacteroids formed by the sucA mutant displayed wild-type rates of respiration and nitrogen fixation. Despite the absence of α-ketoglutarate dehydrogenase activity, whole cells of the mutant were able to decarboxylate α-[U-14C]ketoglutarate and [U-14C]glutamate at rates similar to those of wild-type B. japonicum, indicating that there was an alternative route for α-ketoglutarate catabolism. Because cell extracts from B. japonicum decarboxylated [U-14C]glutamate very slowly, the γ-aminobutyrate shunt is unlikely to be the pathway responsible for α-ketoglutarate catabolism in the mutant. In contrast, cell extracts from both the wild type and mutant showed a coenzyme A (CoA)-independent α-ketoglutarate decarboxylation activity. This activity was independent of pyridine nucleotides and was stimulated by thiamine PPi. Thin-layer chromatography showed that the product of α-ketoglutarate decarboxylation was succinic semialdehyde. The CoA-independent α-ketoglutarate decarboxylase, along with succinate semialdehyde dehydrogenase, may form an alternative pathway for α-ketoglutarate catabolism, and this pathway may enhance <span class="hlt">TCA</span> <span class="hlt">cycle</span> function during symbiotic nitrogen fixation. PMID:10781553</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.4177G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.4177G"><span>Vadose zone controls on damping of climate-induced transient recharge <span class="hlt">fluxes</span> in U.S. agroecosystems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gurdak, Jason</p> <p>2017-04-01</p> <p>Understanding the physical processes in the vadose zone that link climate variability with transient recharge <span class="hlt">fluxes</span> has particular relevance for the sustainability of groundwater-supported irrigated agriculture and other groundwater-dependent ecosystems. Natural climate variability on interannual to multidecadal timescales has well-documented influence on precipitation, evapotranspiration, soil moisture, infiltration <span class="hlt">flux</span>, and can augment or diminish human stresses on water resources. Here the behavior and damping depth of climate-induced transient water <span class="hlt">flux</span> in the vadose zone is explored. The damping depth is the depth in the vadose zone that the <span class="hlt">flux</span> variation damps to 5% of the land surface variation. Steady-state recharge occurs when the damping depth is above the water table, and transient recharge occurs when the damping depth is below the water table. Findings are presented from major agroecosystems of the United States (U.S.), including the High Plains, Central Valley, California Coastal Basin, and Mississippi Embayment aquifer systems. Singular spectrum analysis (SSA) is used to identify quasi-periodic signals in precipitation and groundwater time series that are coincident with the Arctic Oscillation (AO) (6-12 mo <span class="hlt">cycle</span>), Pacific/North American oscillation (PNA) (<1-4 yr <span class="hlt">cycle</span>), El Niño/Southern Oscillation (ENSO) (2-7 yr <span class="hlt">cycle</span>), North Atlantic Oscillation (NAO) (3-6 yr <span class="hlt">cycle</span>), Pacific Decadal Oscillation (PDO) (15-30 yr <span class="hlt">cycle</span>), and Atlantic Multidecadal Oscillation (AMO) (50-70 yr <span class="hlt">cycle</span>). SSA results indicate that nearly all of the quasi-periodic signals in the precipitation and groundwater levels have a statistically significant lag correlation (95% confidence interval) with the AO, PNA, ENSO, NAO, PDO, and AMO indices. Results from HYDRUS-1D simulations indicate that transient water <span class="hlt">flux</span> through the vadose zone are controlled by highly nonlinear interactions between mean infiltration <span class="hlt">flux</span> and infiltration period related to the modes of climate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017E%26PSL.473..154D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017E%26PSL.473..154D"><span>The South Atlantic Anomaly throughout the solar <span class="hlt">cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Domingos, João; Jault, Dominique; Pais, Maria Alexandra; Mandea, Mioara</p> <p>2017-09-01</p> <p>The Sun-Earth's interaction is characterized by a highly dynamic electromagnetic environment, in which the magnetic field produced in the Earth's core plays an important role. One of the striking characteristics of the present geomagnetic field is denoted the South Atlantic Anomaly (SAA) where the total field intensity is unusually low and the <span class="hlt">flux</span> of charged particles, trapped in the inner Van Allen radiation belts, is maximum. Here, we use, on one hand, a recent geomagnetic field model, CHAOS-6, and on the other hand, data provided by different platforms (satellites orbiting the Earth - POES NOAA for 1998-2014 and CALIPSO for 2006-2014). Evolution of the SAA particle <span class="hlt">flux</span> can be seen as the result of two main effects, the secular variation of the Earth's core magnetic field and the modulation of the density of the inner radiation belts during the solar <span class="hlt">cycle</span>, as a function of the L value that characterises the drift shell, where charged particles are trapped. To study the evolution of the particle <span class="hlt">flux</span> anomaly, we rely on a Principal Component Analysis (PCA) of either POES particle <span class="hlt">flux</span> or CALIOP dark noise. Analysed data are distributed on a geographical grid at satellite altitude, based on a L-shell reference frame constructed from the moving eccentric dipole. Changes in the main magnetic field are responsible for the observed westward drift. Three PCA modes account for the time evolution related to solar effects. Both the first and second modes have a good correlation with the thermospheric density, which varies in response to the solar <span class="hlt">cycle</span>. The first mode represents the total intensity variation of the particle <span class="hlt">flux</span> in the SAA, and the second the movement of the anomaly between different L-shells. The proposed analysis allows us to well recover the westward drift rate, as well as the latitudinal and longitudinal solar <span class="hlt">cycle</span> oscillations, although the analysed data do not cover a complete (Hale) magnetic solar <span class="hlt">cycle</span> (around 22 yr). Moreover, the developments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JNuM..329..687L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JNuM..329..687L"><span>High heat <span class="hlt">flux</span> properties of pure tungsten and plasma sprayed tungsten coatings</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, X.; Tamura, S.; Tokunaga, K.; Yoshida, N.; Noda, N.; Yang, L.; Xu, Z.</p> <p>2004-08-01</p> <p>High heat <span class="hlt">flux</span> properties of pure tungsten and plasma sprayed tungsten coatings on carbon substrates have been studied by annealing and cyclic heat loading. The recrystallization temperature and an activation energy QR=126 kJ/mol for grain growth of tungsten coating by vacuum plasma spray (VPS) were estimated, and the microstructural changes of multi-layer tungsten and rhenium interface pre-deposited by physical vapor deposition (PVD) with anneal temperature were investigated. Cyclic load tests indicated that pure tungsten and VPS-tungsten coating could withstand 1000 <span class="hlt">cycles</span> at 33-35 MW/m 2 heat <span class="hlt">flux</span> and 3 s pulse duration, and inert gas plasma spray (IPS)-tungsten coating showed local cracks by 300 <span class="hlt">cycles</span> but did not induce failure by further <span class="hlt">cycles</span>. However, the failure of pure tungsten and VPS-tungsten coating by fatigue cracking was observed under higher heat load (55-60 MW/m 2) for 420 and 230 <span class="hlt">cycles</span>, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1217554','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1217554"><span><span class="hlt">Flux</span> control exerted by mitochondrial outer membrane carnitine palmitoyltransferase over beta-oxidation, ketogenesis and tricarboxylic acid <span class="hlt">cycle</span> activity in hepatocytes isolated from rats in different metabolic states.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Drynan, L; Quant, P A; Zammit, V A</p> <p>1996-01-01</p> <p>The <span class="hlt">Flux</span> Control Coefficients of mitochondrial outer membrane carnitine palmitoyltransferase (CPT I) with respect to the overall rates of beta-oxidation, ketogenesis and tricarboxylic acid <span class="hlt">cycle</span> activity were measured in hepatocytes isolated from rats in different metabolic states (fed, 24 h-starved, starved-refed and starved/insulin-treated). These conditions were chosen because there is controversy as to whether, when significant control ceases to be exerted by CPT I over the rate of fatty oxidation [Moir and Zammit (1994) Trends Biochem. Sci. 19, 313-317], this is transferred to one or more steps proximal to acylcarnitine synthesis (e.g. decreased delivery of fatty acids to the liver) or to the reaction catalysed by mitochondrial 3-hydroxy-3-methyl-glutaryl-CoA synthase [Hegardt (1995) Biochem. Soc. Trans. 23, 486-490]. Therefore isolated hepatocytes were used in the present study to exclude the involvement of changes in the rate of delivery of non-esterified fatty acids (NEFA) to the liver, such as occur in vivo, and to ascertain whether, under conditions of constant supply of NEFA, CPT I retains control over the relevant <span class="hlt">fluxes</span> of fatty acid oxidation to ketones and carbon dioxide, or whether control is transferred to another (intrahepatocytic) site. The results clearly show that the <span class="hlt">Flux</span> Control Coefficients of CPT I with respect to overall beta-oxidation and ketogenesis are very high under all conditions investigated, indicating that control is not lost to another intrahepatic site during the metabolic transitions studied. The control of CPT I over tricarboxylic acid <span class="hlt">cycle</span> activity was always very low. The significance of these findings for the integration of fatty acid and carbohydrate metabolism in the liver is discussed. PMID:8760364</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1355135-how-can-mountaintop-co2-observations-used-constrain-regional-carbon-fluxes','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1355135-how-can-mountaintop-co2-observations-used-constrain-regional-carbon-fluxes"><span>How can mountaintop CO 2 observations be used to constrain regional carbon <span class="hlt">fluxes</span>?</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Lin, John C.; Mallia, Derek V.; Wu, Dien; ...</p> <p>2017-05-03</p> <p>Despite the need for researchers to understand terrestrial biospheric carbon <span class="hlt">fluxes</span> to account for carbon <span class="hlt">cycle</span> feedbacks and predict future CO 2 concentrations, knowledge of these <span class="hlt">fluxes</span> at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon <span class="hlt">fluxes</span>. Yet mountainous regions are often where significant forest cover and biomass are found – i.e., areas that have the potential to serve as carbon sinks. As CO 2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield informationmore » about carbon <span class="hlt">fluxes</span>. In this paper, we present CO 2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon <span class="hlt">fluxes</span> from the CO 2 observations, with emphasis on the observed and simulated diurnal <span class="hlt">cycles</span> of CO 2. We show that atmospheric models can systematically simulate the wrong diurnal <span class="hlt">cycle</span> and significantly misinterpret the CO 2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbated as the spatial resolution is degraded, and our results indicate that a fine grid spacing of ~4 km or less may be needed to simulate a realistic diurnal <span class="hlt">cycle</span> of CO 2 for sites on top of the steep mountains examined here in the American Rockies. In conclusion, in the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO 2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ACP....17.5561L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ACP....17.5561L"><span>How can mountaintop CO2 observations be used to constrain regional carbon <span class="hlt">fluxes</span>?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, John C.; Mallia, Derek V.; Wu, Dien; Stephens, Britton B.</p> <p>2017-05-01</p> <p>Despite the need for researchers to understand terrestrial biospheric carbon <span class="hlt">fluxes</span> to account for carbon <span class="hlt">cycle</span> feedbacks and predict future CO2 concentrations, knowledge of these <span class="hlt">fluxes</span> at the regional scale remains poor. This is particularly true in mountainous areas, where complex meteorology and lack of observations lead to large uncertainties in carbon <span class="hlt">fluxes</span>. Yet mountainous regions are often where significant forest cover and biomass are found - i.e., areas that have the potential to serve as carbon sinks. As CO2 observations are carried out in mountainous areas, it is imperative that they are properly interpreted to yield information about carbon <span class="hlt">fluxes</span>. In this paper, we present CO2 observations at three sites in the mountains of the western US, along with atmospheric simulations that attempt to extract information about biospheric carbon <span class="hlt">fluxes</span> from the CO2 observations, with emphasis on the observed and simulated diurnal <span class="hlt">cycles</span> of CO2. We show that atmospheric models can systematically simulate the wrong diurnal <span class="hlt">cycle</span> and significantly misinterpret the CO2 observations, due to erroneous atmospheric flows as a result of terrain that is misrepresented in the model. This problem depends on the selected vertical level in the model and is exacerbated as the spatial resolution is degraded, and our results indicate that a fine grid spacing of ˜ 4 km or less may be needed to simulate a realistic diurnal <span class="hlt">cycle</span> of CO2 for sites on top of the steep mountains examined here in the American Rockies. In the absence of higher resolution models, we recommend coarse-scale models to focus on assimilating afternoon CO2 observations on mountaintop sites over the continent to avoid misrepresentations of nocturnal transport and influence.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=285578','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=285578"><span>Improved parameterization for the vertical <span class="hlt">flux</span> of dust aerosols emitted by an eroding soil</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>The representation of the dust <span class="hlt">cycle</span> in atmospheric circulation models hinges on an accurate parameterization of the vertical dust <span class="hlt">flux</span> at emission. However, existing parameterizations of the vertical dust <span class="hlt">flux</span> vary substantially in their scaling with wind friction velocity, require input parameters...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890012013','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890012013"><span>Non-random cratering <span class="hlt">flux</span> in recent time</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Schultz, P. H.</p> <p>1988-01-01</p> <p>Proposed periodic <span class="hlt">cycles</span> of mass mortality have been linked to periodic changes in the impact <span class="hlt">flux</span> on Earth. Such changes in the impact <span class="hlt">flux</span>, however, also should be recorded on the Moon. Previous studies have concluded that the impact <span class="hlt">flux</span> on the Moon over the last 1 to 2 billion years has been reasonably constant, but sudden changes in the impact <span class="hlt">flux</span> over time intervals as short as 30 my could not be detected in these studies unless the added crater population greatly exceeded the cumulative cratering record. Consequently this study focuses only on bright-rayed craters larger than 1 km thereby not only limiting the study to recent craters but also largely eliminating contamination by secondary craters. Preservation of ray patterns and other fine-scale surface textures in the ejecta provides first-order culling of craters younger than Tycho, i.e., about 100 my. Although a periodic change in the impact <span class="hlt">flux</span> in the Earth-Moon system cannot yet be confirmed from the data, a non-random component appears to exist with an increased <span class="hlt">flux</span> around 7 and 15 my. The concentrations in different quadrants of the lunar hemisphere would be consistent with a shower of debris generally smaller than 0.5 km.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25887116','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25887116"><span>Sampling with poling-based <span class="hlt">flux</span> balance analysis: optimal versus sub-optimal <span class="hlt">flux</span> space analysis of Actinobacillus succinogenes.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Binns, Michael; de Atauri, Pedro; Vlysidis, Anestis; Cascante, Marta; Theodoropoulos, Constantinos</p> <p>2015-02-18</p> <p><span class="hlt">Flux</span> balance analysis is traditionally implemented to identify the maximum theoretical <span class="hlt">flux</span> for some specified reaction and a single distribution of <span class="hlt">flux</span> values for all the reactions present which achieve this maximum value. However it is well known that the uncertainty in reaction networks due to branches, <span class="hlt">cycles</span> and experimental errors results in a large number of combinations of internal reaction <span class="hlt">fluxes</span> which can achieve the same optimal <span class="hlt">flux</span> value. In this work, we have modified the applied linear objective of <span class="hlt">flux</span> balance analysis to include a poling penalty function, which pushes each new set of reaction <span class="hlt">fluxes</span> away from previous solutions generated. Repeated poling-based <span class="hlt">flux</span> balance analysis generates a sample of different solutions (a characteristic set), which represents all the possible functionality of the reaction network. Compared to existing sampling methods, for the purpose of generating a relatively "small" characteristic set, our new method is shown to obtain a higher coverage than competing methods under most conditions. The influence of the linear objective function on the sampling (the linear bias) constrains optimisation results to a subspace of optimal solutions all producing the same maximal <span class="hlt">fluxes</span>. Visualisation of reaction <span class="hlt">fluxes</span> plotted against each other in 2 dimensions with and without the linear bias indicates the existence of correlations between <span class="hlt">fluxes</span>. This method of sampling is applied to the organism Actinobacillus succinogenes for the production of succinic acid from glycerol. A new method of sampling for the generation of different <span class="hlt">flux</span> distributions (sets of individual <span class="hlt">fluxes</span> satisfying constraints on the steady-state mass balances of intermediates) has been developed using a relatively simple modification of <span class="hlt">flux</span> balance analysis to include a poling penalty function inside the resulting optimisation objective function. This new methodology can achieve a high coverage of the possible <span class="hlt">flux</span> space and can be used with and without</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20170003070&hterms=cycles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcycles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20170003070&hterms=cycles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcycles"><span>Unusual Polar Conditions in Solar <span class="hlt">Cycle</span> 24 and Their Implications for <span class="hlt">Cycle</span> 25</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gopalswamy, Nat; Yashiro, Seiji; Akiyama, Sachiko</p> <p>2016-01-01</p> <p>We report on the prolonged solar-maximum conditions until late 2015 at the north-polar region of the Sun indicated by the occurrence of high-latitude prominence eruptions (PEs) and microwave brightness temperature close to the quiet-Sun level. These two aspects of solar activity indicate that the polarity reversal was completed by mid-2014 in the south and late 2015 in the north. The microwave brightness in the south-polar region has increased to a level exceeding the level of the <span class="hlt">Cycle</span> 23/24 minimum, but just started to increase in the north. The northsouth asymmetry in the polarity reversal has switched from that in <span class="hlt">Cycle</span> 23. These observations lead us to the hypothesis that the onset of <span class="hlt">Cycle</span> 25 in the northern hemisphere is likely to be delayed with respect to that in the southern hemisphere. We find that the unusual condition in the north is a direct consequence of the arrival of poleward surges of opposite polarity from the active region belt. We also find that multiple rush-to-the-pole episodes were indicated by the PE locations that lined up at the boundary between opposite-polarity surges. The high-latitude PEs occurred in the boundary between the incumbent polar <span class="hlt">flux</span> and the insurgent <span class="hlt">flux</span> of opposite polarity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014ApJ...781....8S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014ApJ...781....8S"><span>The Predictability of Advection-dominated <span class="hlt">Flux</span>-transport Solar Dynamo Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sanchez, Sabrina; Fournier, Alexandre; Aubert, Julien</p> <p>2014-01-01</p> <p>Space weather is a matter of practical importance in our modern society. Predictions of forecoming solar <span class="hlt">cycles</span> mean amplitude and duration are currently being made based on <span class="hlt">flux</span>-transport numerical models of the solar dynamo. Interested in the forecast horizon of such studies, we quantify the predictability window of a representative, advection-dominated, <span class="hlt">flux</span>-transport dynamo model by investigating its sensitivity to initial conditions and control parameters through a perturbation analysis. We measure the rate associated with the exponential growth of an initial perturbation of the model trajectory, which yields a characteristic timescale known as the e-folding time τ e . The e-folding time is shown to decrease with the strength of the α-effect, and to increase with the magnitude of the imposed meridional circulation. Comparing the e-folding time with the solar <span class="hlt">cycle</span> periodicity, we obtain an average estimate for τ e equal to 2.76 solar <span class="hlt">cycle</span> durations. From a practical point of view, the perturbations analyzed in this work can be interpreted as uncertainties affecting either the observations or the physical model itself. After reviewing these, we discuss their implications for solar <span class="hlt">cycle</span> prediction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFM.H13K..02H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFM.H13K..02H"><span>A Satellite View of Global Water and Energy <span class="hlt">Cycling</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Houser, P. R.</p> <p>2012-12-01</p> <p>The global water <span class="hlt">cycle</span> describes liquid, solid and vapor water dynamics as it moves through the atmosphere, oceans and land. Life exists because of water, and civilization depends on adapting to the constraints imposed by water availability. The carbon, water and energy <span class="hlt">cycles</span> are strongly interdependent - energy is moved through evaporation and condensation, and photosynthesis is closely related to transpiration. There are significant knowledge gaps about water storage, <span class="hlt">fluxes</span> and dynamics - we currently do not really know how much water is stored in snowpacks, groundwater or reservoirs. The view from space offers a vision for water science advancement. This vision includes observation, understanding, and prediction advancements that will improve water management and to inform water-related infrastructure that planning to provide for human needs and to protect the natural environment. The water <span class="hlt">cycle</span> science challenge is to deploy a series of coordinated earth observation satellites, and to integrate in situ and space-borne observations to quantify the key water-<span class="hlt">cycle</span> state variables and <span class="hlt">fluxes</span>. The accompanying societal challenge is to integrate this information along with water <span class="hlt">cycle</span> physics, and ecosystems and societal considerations as a basis for enlightened water resource management and to protect life and property from effects of water <span class="hlt">cycle</span> extremes. Better regional to global scale water-<span class="hlt">cycle</span> observations and predictions need to be readily available to reduce loss of life and property caused by water-related hazards. To this end, the NASA Energy and Water <span class="hlt">cycle</span> Study (NEWS) has been documenting the satellite view of the water <span class="hlt">cycle</span> with a goal of enabling improved, observationally based, predictions of water and energy <span class="hlt">cycle</span> consequences of Earth system variability and change. NEWS has fostered broad interdisciplinary collaborations to study experimental and operational satellite observations and has developed analysis tools for characterizing air</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1339984','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1339984"><span>A new Micro<span class="hlt">TCA</span>-based waveform digitizer for the Muon g-2 experiment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Sweigart, David A.</p> <p></p> <p>We present the design of a newmore » $$\\mu$$<span class="hlt">TCA</span>-based waveform digitizer, which will be deployed in the Muon g-2 experiment at Fermilab and will allow our pileup identification requirement to be met. This digitizer features five independent channels, each with 12-bit, 800-MSPS digitization and a 1-Gbit memory buffer. The data storage and readout along with configuration are handled by six Xilinx Kintex-7 FPGAs. In addition, the digitizer is equipped with a mezzanine card for analog signal conditioning prior to digitization, further widening its range of possible applications. The performance results of this design are also presented, highlighting its $$0.51 \\pm 0.13$$ mV intrinsic noise level and $< 22$ ps intrinsic timing resolution between channels. We believe that its performance, together with its flexible design, could be of interest to future experiments in search of a cost-effective waveform digitizer.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20060010532','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20060010532"><span>Simplified Solar Modulation Model of Inner Trapped Belt Proton <span class="hlt">Flux</span> As a Function of Atmospheric Density</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, Thomas L.; Lodhi, M. A. K.; Diaz, Abel B.</p> <p>2005-01-01</p> <p>No simple algorithm seems to exist for calculating proton <span class="hlt">fluxes</span> and lifetimes in the Earth's inner, trapped radiation belt throughout the solar <span class="hlt">cycle</span>. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in <span class="hlt">Cycle</span> 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton <span class="hlt">fluxes</span> at any time in a given solar <span class="hlt">cycle</span>, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From <span class="hlt">flux</span> and its time integral fluence, one can then approximate dose rate and its time integral dose. It has already been published in this journal that the absorbed dose rate, D, in the trapped belts exhibits a power law relationship, D = A(rho)(sup -n), where A is a constant, rho is the atmospheric density, and the index n is weakly dependent upon shielding. However, that method does not work for <span class="hlt">flux</span> and fluence. Instead, we extend this idea by showing that the power law approximation for <span class="hlt">flux</span> J is actually bivariant in energy E as well as density rho. The resulting relation is J(E,rho)approx.(sum of)A(E(sup n))rho(sup -n), with A itself a power law in E. This provides another method for calculating approximate proton <span class="hlt">flux</span> and lifetime at any time in the solar <span class="hlt">cycle</span>. These in turn can be used to predict the associated dose and dose rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5947981','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5947981"><span>High-<span class="hlt">flux</span> soft x-ray harmonic generation from ionization-shaped few-<span class="hlt">cycle</span> laser pulses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Brahms, Christian; Gregory, Andrew; Tisch, John W. G.; Marangos, Jon P.</p> <p>2018-01-01</p> <p>Laser-driven high-harmonic generation provides the only demonstrated route to generating stable, tabletop attosecond x-ray pulses but has low <span class="hlt">flux</span> compared to other x-ray technologies. We show that high-harmonic generation can produce higher photon energies and <span class="hlt">flux</span> by using higher laser intensities than are typical, strongly ionizing the medium and creating plasma that reshapes the driving laser field. We obtain high harmonics capable of supporting attosecond pulses up to photon energies of 600 eV and a photon <span class="hlt">flux</span> inside the water window (284 to 540 eV) 10 times higher than previous attosecond sources. We demonstrate that operating in this regime is key for attosecond pulse generation in the x-ray range and will become increasingly important as harmonic generation moves to fields that drive even longer wavelengths. PMID:29756033</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25146464','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25146464"><span>Oxygenated monoterpenes citral and carvacrol cause oxidative damage in Escherichia coli without the involvement of tricarboxylic acid <span class="hlt">cycle</span> and Fenton reaction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chueca, Beatriz; Pagán, Rafael; García-Gonzalo, Diego</p> <p>2014-10-17</p> <p>Oxygenated monoterpenes citral and carvacrol are common constituents of many essential oils (EOs) that have been extensively studied as antimicrobial agents but whose mechanisms of microbial inactivation have not been totally elucidated. A recent study described a mechanism of Escherichia coli death for (+)-limonene, a hydrocarbon monoterpene also frequently present in EOs, similar to the common mechanism proposed for bactericidal antibiotics. This mechanism involves the formation of Fenton-mediated hydroxyl radical, a reactive oxygen species (ROS), via tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span>, which would ultimately inactivate cells. Our objective was to determine whether E. coli MG1655 inactivation by citral and carvacrol follows a similar mechanism of cell death. Challenging experiments with 300μL/L citral and 100μL/L carvacrol inactivated at least 2.5log10<span class="hlt">cycles</span> of exponentially growing cells in 3h under aerobic conditions. The presence of thiourea (an ROS scavenger) reduced cell inactivation in 2log10<span class="hlt">cycles</span>, demonstrating the role of ROS in cell death. Decreased resistance of a ΔrecA mutant (deficient in an enzyme involved in SOS response to DNA damage) indicated that citral and carvacrol caused oxidative damage to DNA. Although the mechanism of E. coli inactivation by carvacrol and citral was similarly mediated by ROS, their formation did not follow the same pathways described for (+)-limonene and bactericidal drugs because neither Fenton reaction nor NADH production via the <span class="hlt">TCA</span> <span class="hlt">cycle</span> was involved in cell death. Moreover, further experiments demonstrated antimicrobial activity of citral and carvacrol in anaerobic environments without the involvement of ROS. As a consequence, cell death by carvacrol and citral in anaerobiosis follows a different mechanism than that observed under aerobic conditions. These results demonstrated a different mechanism of inactivation by citral and carvacrol with regard to (+)-limonene and bactericidal antibiotics, indicating the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018WRR....54.2452C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018WRR....54.2452C"><span>Quantifying Surface Water, Porewater, and Groundwater Interactions Using Tracers: Tracer <span class="hlt">Fluxes</span>, Water <span class="hlt">Fluxes</span>, and End-member Concentrations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cook, Peter G.; Rodellas, Valentí; Stieglitz, Thomas C.</p> <p>2018-03-01</p> <p>Tracer approaches to estimate both porewater exchange (the <span class="hlt">cycling</span> of water between surface water and sediments, with zero net water <span class="hlt">flux</span>) and groundwater inflow (the net flow of terrestrially derived groundwater into surface water) are commonly based on solute mass balances. However, this requires appropriate characterization of tracer end-member concentrations in exchanging or discharging water. Where either porewater exchange or groundwater inflow to surface water occur in isolation, then the water <span class="hlt">flux</span> is easily estimated from the net tracer <span class="hlt">flux</span> if the end-member is appropriately chosen. However, in most natural systems porewater exchange and groundwater inflow will occur concurrently. Our analysis shows that if groundwater inflow (Qg) and porewater exchange (Qp) mix completely before discharging to surface water, then the combined water <span class="hlt">flux</span> (Qg + Qp) can be approximated by dividing the combined tracer <span class="hlt">flux</span> by the difference between the porewater and surface water concentrations, (cp - c). If Qg and Qp do not mix prior to discharge, then (Qg + Qp) can only be constrained by minimum and maximum values. The minimum value is obtained by dividing the net tracer <span class="hlt">flux</span> by the groundwater concentration, and the maximum is obtained by dividing by (cp - c). Dividing by the groundwater concentration gives a maximum value for Qg. If porewater exchange and groundwater outflow occur concurrently, then dividing the net tracer <span class="hlt">flux</span> by (cp - c) will provide a minimum value for Qp. Use of multiple tracers, and spatial and temporal replication should provide a more complete picture of exchange processes and the extent of subsurface mixing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16338960','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16338960"><span>Photoinactivation of ascorbate peroxidase in isolated tobacco chloroplasts: Galdieria partita APX maintains the electron <span class="hlt">flux</span> through the water-water <span class="hlt">cycle</span> in transplastomic tobacco plants.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Miyake, Chikahiro; Shinzaki, Yuki; Nishioka, Minori; Horiguchi, Sayaka; Tomizawa, Ken-Ichi</p> <p>2006-02-01</p> <p>We evaluated the H2O2-scavenging activity of the water-water <span class="hlt">cycle</span> (WWC) in illuminated intact chloroplasts isolated from tobacco leaves. Illumination under conditions that limited photosynthesis [red light (>640 nm), 250 micromol photons m(-2) s(-1) in the absence of HCO3-] caused chloroplasts to take up O2 and accumulate H2O2. Concomitant with the O2 uptake, both ascorbate peroxidase (APX) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) lost their activities. However, superoxide dismutase (SOD), monodehydroascorbate radical reductase (MDAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) activities remained unaffected. The extent to which the photosynthetic linear electron flow decreased was small compared with the decline in APX activity. Therefore, the loss of APX activity lowered the electron <span class="hlt">flux</span> through the WWC, as evidenced by a decrease in relative electron <span class="hlt">flux</span> through PSII [Phi(PSII)xPFD]. To verify these interpretations, we created a transplastomic tobacco line in which an H2O2-insensitive APX from the red alga, Galdieria partita, was overproduced in the chloroplasts. In intact transplastomic chloroplasts which were illuminated under conditions that limited photosynthesis, neither O2 uptake nor H2O2 accumulation occurred. Furthermore, the electron <span class="hlt">flux</span> through the WWC and the activity of GAPDH were maintained. The present work is the first report of APX inactivation by endogenous H2O2 in intact chloroplasts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26318243','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26318243"><span>(13)C-metabolic <span class="hlt">flux</span> analysis of lipid accumulation in the oleaginous fungus Mucor circinelloides.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Lina; Zhang, Huaiyuan; Wang, Liping; Chen, Haiqin; Chen, Yong Q; Chen, Wei; Song, Yuanda</p> <p>2015-12-01</p> <p>The oleaginous fungus Mucor circinelloides is of industrial interest because it can produce high levels of polyunsaturated fatty acid γ-linolenic acid. M. circinelloides CBS 277.49 is able to accumulate less than 15% of cell dry weight as lipids, while M. circinelloides WJ11 can accumulate lipid up to 36%. In order to better understand the mechanisms behind the differential lipid accumulation in these two strains, tracer experiments with (13)C-glucose were performed with the growth of M. circinelloides and subsequent gas chromatography-mass spectrometric detection of (13)C-patterns in proteinogenic amino acids was carried out to identify the metabolic network topology and estimate intracellular <span class="hlt">fluxes</span>. Our results showed that the high oleaginous strain WJ11 had higher <span class="hlt">flux</span> of pentose phosphate pathway and malic enzyme, lower <span class="hlt">flux</span> in tricarboxylic acid <span class="hlt">cycle</span>, higher <span class="hlt">flux</span> in glyoxylate <span class="hlt">cycle</span> and ATP: citrate lyase, together, it might provide more NADPH and substrate acetyl-CoA for fatty acid synthesis. Copyright © 2015 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH13A2473P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH13A2473P"><span>Using the Solar Polar Magnetic Field for Longterm Predictions of Solar Activity, Solar <span class="hlt">Cycles</span> 21-25</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pesnell, W. D.; Schatten, K. H.</p> <p>2017-12-01</p> <p>We briefly review the dynamo and geomagnetic precursor methods of long-term solar activity forecasting. These methods depend upon the most basic aspect of dynamo theory to predict future activity, future magnetic field arises directly from the amplification of pre-existing magnetic field. We then generalize the dynamo technique, allowing the method to be used at any phase of the solar <span class="hlt">cycle</span>, to the Solar Dynamo Amplitude (SODA) index. This index is sensitive to the magnetic <span class="hlt">flux</span> trapped within the Sun's convection zone but insensitive to the phase of the solar <span class="hlt">cycle</span>. Since magnetic fields inside the Sun can become buoyant, one may think of the acronym SODA as describing the amount of buoyant <span class="hlt">flux</span>. We will show how effective the SODA Index has been in predicting Solar <span class="hlt">Cycles</span> 23 and 24, and present a unified picture of earlier estimates of the polar magnetic configuration in Solar <span class="hlt">Cycle</span> 21 and 22. Using the present value of the SODA index, we estimate that the next <span class="hlt">cycle</span>'s smoothed peak activity will be about 125 ± 30 solar <span class="hlt">flux</span> units for the 10.7 cm radio <span class="hlt">flux</span> and a sunspot number of 70 ± 25. This suggests that Solar <span class="hlt">Cycle</span> 25 will be comparable to Solar <span class="hlt">Cycle</span> 24. Since the current approach uses data prior to solar minimum, these estimates may improve when the upcoming solar minimum is reached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080023465','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080023465"><span>A Preliminary Study of CO2 <span class="hlt">Flux</span> Measurements by Lidar</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gibert, Fabien; Koch, Grady J.; Beyon, Jeffrey Y.; Hilton, T.; Davis, Kenneth J.; Andrews, Arlyn; Ismail, Syed; Singh, Upendra N.</p> <p>2008-01-01</p> <p>A mechanistic understanding of the global carbon <span class="hlt">cycle</span> requires quantification of terrestrial ecosystem CO2 <span class="hlt">fluxes</span> at regional scales. In this paper, we analyze the potential of a Doppler DIAL system to make <span class="hlt">flux</span> measurements of atmospheric CO2 using the eddy-covariance and boundary layer budget methods and present results from a ground based experiment. The goal of this study is to put CO2 <span class="hlt">flux</span> point measurements in a mesoscale context. In June 2007, a field experiment combining a 2-m Doppler Heterodyne Differential Absorption Lidar (HDIAL) and in-situ sensors of a 447-m tall tower (WLEF) took place in Wisconsin. The HDIAL measures simultaneously: 1) CO2 mixing ratio, 2) atmosphere structure via aerosol backscatter and 3) radial velocity. We demonstrate how to synthesize these data into regional <span class="hlt">flux</span> estimates. Lidar-inferred <span class="hlt">fluxes</span> are compared with eddy-covariance <span class="hlt">fluxes</span> obtained in-situ at 396m AGL from the tower. In cases where the lidar was not yet able to measure the <span class="hlt">fluxes</span> with acceptable precision, we discuss possible modifications to improve system performance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018sptz.prop14110M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018sptz.prop14110M"><span>'Where's the <span class="hlt">flux</span>' star: Where's the excess?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meng, Huan; Boyajian, Tabetha; Kennedy, Grant; Lisse, Carey; Marengo, Massimo; Wright, Jason; Wyatt, Mark</p> <p>2018-05-01</p> <p>KIC 8462852 provides, in real time, the rare chance to observe cataclysmic events happening in a mature extrasolar planetary system. The Kepler light curve of the star sees two major dips 750 days apart with depths of 20%, as well as a number of smaller dips ( 1%) at apparently random time. A series of new, shallow (2-4% in <span class="hlt">flux</span>) dips has been observed since May 2017 and as late as March 2018. In addition to the days-long dips, the star has also been found to have long-term variations over years, and possibly centuries. Conclusions from existing observations suggest that the dips and long-term variations are likely caused by transits of dust clumps in front of the star. We have observed KIC 8462852 with Spitzer/IRAC since <span class="hlt">cycle</span> 12. We propose to continue the monitoring in <span class="hlt">cycle</span> 14 to track the long-term variations of the stellar <span class="hlt">flux</span>, measure the optical properties of the transit dust, and look for possible transient excess if new dips happen close in time to our observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H11N..03A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H11N..03A"><span>Ambient groundwater flow diminishes nitrogen <span class="hlt">cycling</span> in streams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Azizian, M.; Grant, S. B.; Rippy, M.; Detwiler, R. L.; Boano, F.; Cook, P. L. M.</p> <p>2017-12-01</p> <p>Modeling and experimental studies demonstrate that ambient groundwater reduces hyporheic exchange, but the implications of this observation for stream N-<span class="hlt">cycling</span> is not yet clear. We utilized a simple process-based model (the Pumping and Streamline Segregation or PASS model) to evaluate N- <span class="hlt">cycling</span> over two scales of hyporheic exchange (fluvial ripples and riffle-pool sequences), ten ambient groundwater and stream flow scenarios (five gaining and losing conditions and two stream discharges), and three biogeochemical settings (identified based on a principal component analysis of previously published measurements in streams throughout the United States). Model-data comparisons indicate that our model provides realistic estimates for direct denitrification of stream nitrate, but overpredicts nitrification and coupled nitrification-denitrification. Riffle-pool sequences are responsible for most of the N-processing, despite the fact that fluvial ripples generate 3-11 times more hyporheic exchange <span class="hlt">flux</span>. Across all scenarios, hyporheic exchange <span class="hlt">flux</span> and the Damkohler Number emerge as primary controls on stream N-<span class="hlt">cycling</span>; the former regulates trafficking of nutrients and oxygen across the sediment-water interface, while the latter quantifies the relative rates of organic carbon mineralization and advective transport in streambed sediments. Vertical groundwater <span class="hlt">flux</span> modulates both of these master variables in ways that tend to diminish stream N-<span class="hlt">cycling</span>. Thus, anthropogenic perturbations of ambient groundwater flows (e.g., by urbanization, agricultural activities, groundwater mining, and/or climate change) may compromise some of the key ecosystem services provided by streams.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1246061','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1246061"><span>Ameri<span class="hlt">Flux</span> US-Ho1 Howland Forest (main tower)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service</p> <p>2016-01-01</p> <p>This is the Ameri<span class="hlt">Flux</span> version of the carbon <span class="hlt">flux</span> data for the site US-Ho1 Howland Forest (main tower). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical <span class="hlt">Cycles</span> 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1246062','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1246062"><span>Ameri<span class="hlt">Flux</span> US-Ho2 Howland Forest (west tower)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service</p> <p>2016-01-01</p> <p>This is the Ameri<span class="hlt">Flux</span> version of the carbon <span class="hlt">flux</span> data for the site US-Ho2 Howland Forest (west tower). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical <span class="hlt">Cycles</span> 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1246063','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1246063"><span>Ameri<span class="hlt">Flux</span> US-Ho3 Howland Forest (harvest site)</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Hollinger, David [USDA Forest Service; Hollinger, David [USDA Forest Service</p> <p>2016-01-01</p> <p>This is the Ameri<span class="hlt">Flux</span> version of the carbon <span class="hlt">flux</span> data for the site US-Ho3 Howland Forest (harvest site). Site Description - Closed conifer forest, minimal disturbance. References: Fernandez et al. (1993), Canadian Journal of Soil Science 73 317-328. Hollinger et al. (1999), Global Change Biology 5: 891-902. Savage KE, Davidson EA (2001), Global Biogeochemical <span class="hlt">Cycles</span> 15 337-350. Scott et al. (2004), Environmental Management, Vol. 33, Supplement 1, pp. S9-S22. Hollinger et al. (2004), Global Change Biology 10: 1689-1706.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25869135','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25869135"><span>Biochemical Validation of the Glyoxylate <span class="hlt">Cycle</span> in the Cyanobacterium Chlorogloeopsis fritschii Strain PCC 9212.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhang, Shuyi; Bryant, Donald A</p> <p>2015-05-29</p> <p>Cyanobacteria are important photoautotrophic bacteria with extensive but variable metabolic capacities. The existence of the glyoxylate <span class="hlt">cycle</span>, a variant of the <span class="hlt">TCA</span> <span class="hlt">cycle</span>, is still poorly documented in cyanobacteria. Previous studies reported the activities of isocitrate lyase and malate synthase, the key enzymes of the glyoxylate <span class="hlt">cycle</span> in some cyanobacteria, but other studies concluded that these enzymes are missing. In this study the genes encoding isocitrate lyase and malate synthase from Chlorogloeopsis fritschii PCC 9212 were identified, and the recombinant enzymes were biochemically characterized. Consistent with the presence of the enzymes of the glyoxylate <span class="hlt">cycle</span>, C. fritschii could assimilate acetate under both light and dark growth conditions. Transcript abundances for isocitrate lyase and malate synthase increased, and C. fritschii grew faster, when the growth medium was supplemented with acetate. Adding acetate to the growth medium also increased the yield of poly-3-hydroxybutyrate. When the genes encoding isocitrate lyase and malate synthase were expressed in Synechococcus sp. PCC 7002, the acetate assimilation capacity of the resulting strain was greater than that of wild type. Database searches showed that the genes for the glyoxylate <span class="hlt">cycle</span> exist in only a few other cyanobacteria, all of which are able to fix nitrogen. This study demonstrates that the glyoxylate <span class="hlt">cycle</span> exists in a few cyanobacteria, and that this pathway plays an important role in the assimilation of acetate for growth in one of those organisms. The glyoxylate <span class="hlt">cycle</span> might play a role in coordinating carbon and nitrogen metabolism under conditions of nitrogen fixation. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS24A..04D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS24A..04D"><span>Diagnosis of CO2 <span class="hlt">Fluxes</span> in the Coastal Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dai, M.; Cao, Z.; Yang, W.; Guo, X.; Yin, Z.; Zhao, Y.</p> <p>2017-12-01</p> <p>Coastal ocean carbon is an important component of the global carbon <span class="hlt">cycle</span>. However, its mechanistic-based conceptualization, a prerequisite of coastal carbon modeling and its inclusion in the Earth System Model, remains difficult due to the highest variability in both time and space. Here we show that the inter-seasonal change of the global coastal pCO2 is more determined by non-temperature factors such as biological drawdown and water mass mixing, the latter of which features the dynamic boundary processes of the coastal ocean at both land-margin and margin-open ocean interfaces. Considering these unique features, we resolve the coastal CO2 <span class="hlt">fluxes</span> using a semi-analytical approach coupling physics-biogeochemistry and carbon-nutrients and conceptualize the coastal carbon <span class="hlt">cycle</span> into Ocean-dominated Margins (OceMar) and River-dominated Ocean Margins (RiOMar). The diagnostic result of CO2 <span class="hlt">fluxes</span> in the South China Sea basin and the Arabian Sea as OceMars and in the Pearl River Plume as a RioMar is consistent with field observations. Our mechanistic-based diagnostic approach therefore helps better understand and model coastal carbon <span class="hlt">cycle</span> yet the stoichiometry of carbon-nutrients coupling needs scrutiny when applying our approach.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V12A..08Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V12A..08Z"><span>Mantle Volatiles and Global Carbon <span class="hlt">Flux</span> and Budget</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.</p> <p>2014-12-01</p> <p>The global volcanic carbon <span class="hlt">flux</span> to the surface of Earth is a fundamental parameter in understanding the global carbon <span class="hlt">cycle</span> that includes deep carbon as well as the degassing history of the mantle. The <span class="hlt">flux</span> has been estimated before (e.g., Marty and Tolstikhin, 1998). Recent progress has significantly revised some of the parameters used in the estimation, e.g., the oceanic 3He <span class="hlt">flux</span> has been re-evaluated (Bianchi et al., 2010) to be only about half of the earlier widely-used estimate, and numerous subaerial volcanic degassing data are now available. In this report, a new attempt is made to assess the global carbon <span class="hlt">flux</span> and budget. Rather than dividing the carbon <span class="hlt">flux</span> by categories of MORB, Plumes and Arcs, we estimate the global carbon <span class="hlt">flux</span> by considering oceanic and subaerial volcanism. The oceanic 3He <span class="hlt">flux</span> is 527±102 mol/yr (Bianchi et al., 2010). Most of the <span class="hlt">flux</span> is from spreading ridges with only minor contributions from submarine oceanic hotspots or arc volcanism. Hence, the mean CO2/3He ratio in MORB is applied to estimate oceanic <span class="hlt">flux</span> of CO2. The subaerial CO2 <span class="hlt">flux</span> is based on evaluation of different arc segments and is messier to compute. Literature estimates use estimated SO2 <span class="hlt">flux</span> in the last tens of years combined with estimated CO2/SO2 degassing ratios (Hilton et al., 2002; Fischer, 2008). Assuming that the last tens of years are representative of recent geological times in terms of volcanic degassing, the estimated global CO2 <span class="hlt">flux</span> still depends critically on a couple of arcs that are main contributors of the subaerial volcanic CO2 <span class="hlt">flux</span>, and those seem to have been rather loosely constrained before. Using recently available data (although there are still holes), we derive a new global subaerial volcanic CO2 <span class="hlt">flux</span>. By combining with oceanic volcanic CO2 <span class="hlt">flux</span>, we obtain at a new global <span class="hlt">flux</span>. The significance of the new estimate to the global volatile budget will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015GeoRL..42.6014L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015GeoRL..42.6014L"><span>Dust <span class="hlt">fluxes</span> and iron fertilization in Holocene and Last Glacial Maximum climates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lambert, Fabrice; Tagliabue, Alessandro; Shaffer, Gary; Lamy, Frank; Winckler, Gisela; Farias, Laura; Gallardo, Laura; De Pol-Holz, Ricardo</p> <p>2015-07-01</p> <p>Mineral dust aerosols play a major role in present and past climates. To date, we rely on climate models for estimates of dust <span class="hlt">fluxes</span> to calculate the impact of airborne micronutrients on biogeochemical <span class="hlt">cycles</span>. Here we provide a new global dust <span class="hlt">flux</span> data set for Holocene and Last Glacial Maximum (LGM) conditions based on observational data. A comparison with dust <span class="hlt">flux</span> simulations highlights regional differences between observations and models. By forcing a biogeochemical model with our new data set and using this model's results to guide a millennial-scale Earth System Model simulation, we calculate the impact of enhanced glacial oceanic iron deposition on the LGM-Holocene carbon <span class="hlt">cycle</span>. On centennial timescales, the higher LGM dust deposition results in a weak reduction of <10 ppm in atmospheric CO2 due to enhanced efficiency of the biological pump. This is followed by a further ~10 ppm reduction over millennial timescales due to greater carbon burial and carbonate compensation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29229856','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29229856"><span>Global biogeochemical <span class="hlt">cycle</span> of vanadium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Schlesinger, William H; Klein, Emily M; Vengosh, Avner</p> <p>2017-12-26</p> <p>Synthesizing published data, we provide a quantitative summary of the global biogeochemical <span class="hlt">cycle</span> of vanadium (V), including both human-derived and natural <span class="hlt">fluxes</span>. Through mining of V ores (130 × 10 9 g V/y) and extraction and combustion of fossil fuels (600 × 10 9 g V/y), humans are the predominant force in the geochemical <span class="hlt">cycle</span> of V at Earth's surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric <span class="hlt">flux</span> probably derives from emissions from the combustion of fossil fuels, but the magnitude of this <span class="hlt">flux</span> depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the <span class="hlt">flux</span> of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced-with about 40 × 10 9 g V/y to 50 × 10 9 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5748214','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5748214"><span>Global biogeochemical <span class="hlt">cycle</span> of vanadium</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Klein, Emily M.; Vengosh, Avner</p> <p>2017-01-01</p> <p>Synthesizing published data, we provide a quantitative summary of the global biogeochemical <span class="hlt">cycle</span> of vanadium (V), including both human-derived and natural <span class="hlt">fluxes</span>. Through mining of V ores (130 × 109 g V/y) and extraction and combustion of fossil fuels (600 × 109 g V/y), humans are the predominant force in the geochemical <span class="hlt">cycle</span> of V at Earth’s surface. Human emissions of V to the atmosphere are now likely to exceed background emissions by as much as a factor of 1.7, and, presumably, we have altered the deposition of V from the atmosphere by a similar amount. Excessive V in air and water has potential, but poorly documented, consequences for human health. Much of the atmospheric <span class="hlt">flux</span> probably derives from emissions from the combustion of fossil fuels, but the magnitude of this <span class="hlt">flux</span> depends on the type of fuel, with relatively low emissions from coal and higher contributions from heavy crude oils, tar sands bitumen, and petroleum coke. Increasing interest in petroleum derived from unconventional deposits is likely to lead to greater emissions of V to the atmosphere in the near future. Our analysis further suggests that the <span class="hlt">flux</span> of V in rivers has been incremented by about 15% from human activities. Overall, the budget of dissolved V in the oceans is remarkably well balanced—with about 40 × 109 g V/y to 50 × 109 g V/y inputs and outputs, and a mean residence time for dissolved V in seawater of about 130,000 y with respect to inputs from rivers. PMID:29229856</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRD..123.1460C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRD..123.1460C"><span>On the Ability of Space-Based Passive and Active Remote Sensing Observations of CO2 to Detect <span class="hlt">Flux</span> Perturbations to the Carbon <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crowell, Sean M. R.; Randolph Kawa, S.; Browell, Edward V.; Hammerling, Dorit M.; Moore, Berrien; Schaefer, Kevin; Doney, Scott C.</p> <p>2018-01-01</p> <p>Space-borne observations of CO2 are vital to gaining understanding of the carbon <span class="hlt">cycle</span> in regions of the world that are difficult to measure directly, such as the tropical terrestrial biosphere, the high northern and southern latitudes, and in developing nations such as China. Measurements from passive instruments such as GOSAT and OCO-2, however, are constrained by solar zenith angle limitations as well as sensitivity to the presence of clouds and aerosols. Active measurements such as those in development for the Active Sensing of CO2 Emissions over Nights, Days and Seasons (ASCENDS) mission show strong potential for making measurements in the high-latitude winter and in cloudy regions. In this work we examine the enhanced <span class="hlt">flux</span> constraint provided by the improved coverage from an active measurement such as ASCENDS. The simulation studies presented here show that with sufficient precision, ASCENDS will detect permafrost thaw and fossil fuel emissions shifts at annual and seasonal time scales, even in the presence of transport errors, representativeness errors, and biogenic <span class="hlt">flux</span> errors. While OCO-2 can detect some of these perturbations at the annual scale, the seasonal sampling provided by ASCENDS provides the stronger constraint.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930022365','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930022365"><span>Thin film heat <span class="hlt">flux</span> sensor for Space Shuttle Main Engine turbine environment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Will, Herbert</p> <p>1991-01-01</p> <p>The Space Shuttle Main Engine (SSME) turbine environment stresses engine components to their design limits and beyond. The extremely high temperatures and rapid temperature <span class="hlt">cycling</span> can easily cause parts to fail if they are not properly designed. Thin film heat <span class="hlt">flux</span> sensors can provide heat loading information with almost no disturbance of gas flows or of the blade. These sensors can provide steady state and transient heat <span class="hlt">flux</span> information. A thin film heat <span class="hlt">flux</span> sensor is described which makes it easier to measure small temperature differences across very thin insulating layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://pubs.acs.org/doi/abs/10.1021/es500781g','USGSPUBS'); return false;" href="http://pubs.acs.org/doi/abs/10.1021/es500781g"><span>Hydrological controls on methylmercury distribution and <span class="hlt">flux</span> in a tidal marsh</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Zhang, Hua; Moffett, Kevan B.; Windham-Myers, Lisamarie; Gorelick, Steven M.</p> <p>2014-01-01</p> <p>The San Francisco Estuary, California, contains mercury (Hg) contamination originating from historical regional gold and Hg mining operations. We measured hydrological and geochemical variables in a tidal marsh of the Palo Alto Baylands Nature Preserve to determine the sources, location, and magnitude of hydrological <span class="hlt">fluxes</span> of methylmercury (MeHg), a bioavailable Hg species of ecological and health concern. Based on measured concentrations and detailed finite-element simulation of coupled surface water and saturated-unsaturated groundwater flow, we found pore water MeHg was concentrated in unsaturated pockets that persisted over tidal <span class="hlt">cycles</span>. These pockets, occurring over 16% of the marsh plain area, corresponded to the marsh root zone. Groundwater discharge (e.g., exfiltration) to the tidal channel represented a significant source of MeHg during low tide. We found that nonchannelized flow accounted for up to 20% of the MeHg <span class="hlt">flux</span> to the estuary. The estimated net <span class="hlt">flux</span> of filter-passing (0.45 μm) MeHg toward estuary was 10 ± 5 ng m–2 day–1 during a single 12-h tidal <span class="hlt">cycle</span>, suggesting an annual MeHg load of 1.17 ± 0.58 kg when the estimated <span class="hlt">flux</span> was applied to present tidal marshes and planned marsh restorations throughout the San Francisco Estuary.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29417234','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29417234"><span>Diel and seasonal nitrous oxide <span class="hlt">fluxes</span> determined by floating chamber and gas transfer equation methods in agricultural irrigation watersheds in southeast China.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, Shuang; Chen, Jie; Li, Chen; Kong, Delei; Yu, Kai; Liu, Shuwei; Zou, Jianwen</p> <p>2018-02-07</p> <p>Agricultural nitrate leaching and runoff incurs high nitrogen loads in agricultural irrigation watersheds, constituting one of important sources of atmospheric nitrous oxide (N 2 O). Two independent sampling campaigns of N 2 O <span class="hlt">flux</span> measurement over diel <span class="hlt">cycles</span> and N 2 O <span class="hlt">flux</span> measurements once a week over annual <span class="hlt">cycles</span> were carried out in an agricultural irrigation watershed in southeast China using floating chamber (chamber-based) and gas transfer equation (model-based) methods. The diel and seasonal patterns of N 2 O <span class="hlt">fluxes</span> did not differ between the two measurement methods. The diel variation in N 2 O <span class="hlt">fluxes</span> was characterized by the pattern that N 2 O <span class="hlt">fluxes</span> were greater during nighttime than daytime periods with a single <span class="hlt">flux</span> peak at midnight. The diel variation in N 2 O <span class="hlt">fluxes</span> was closely associated with water environment and chemistry. The time interval of 9:00-11:00 a.m. was identified to be the sampling time best representing daily N 2 O <span class="hlt">flux</span> measurements in agricultural irrigation watersheds. Seasonal N 2 O <span class="hlt">fluxes</span> showed large variation, with some <span class="hlt">flux</span> peaks corresponding to agricultural irrigation and drainage episodes and heavy rainfall during the crop-growing period of May to November. On average, N 2 O <span class="hlt">fluxes</span> calculated by model-based methods were 27% lower than those determined by the chamber-based techniques over diel or annual <span class="hlt">cycles</span>. Overall, more measurement campaigns are highly needed to assess regional agricultural N 2 O budget with low uncertainties.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27094026','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27094026"><span>Protein precipitation of diluted samples in SDS-containing buffer with acetone leads to higher protein recovery and reproducibility in comparison with <span class="hlt">TCA</span>/acetone approach.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Santa, Cátia; Anjo, Sandra I; Manadas, Bruno</p> <p>2016-07-01</p> <p>Proteomic approaches are extremely valuable in many fields of research, where mass spectrometry methods have gained an increasing interest, especially because of the ability to perform quantitative analysis. Nonetheless, sample preparation prior to mass spectrometry analysis is of the utmost importance. In this work, two protein precipitation approaches, widely used for cleaning and concentrating protein samples, were tested and compared in very diluted samples solubilized in a strong buffer (containing SDS). The amount of protein recovered after acetone and <span class="hlt">TCA</span>/acetone precipitation was assessed, as well as the protein identification and relative quantification by SWATH-MS yields were compared with the results from the same sample without precipitation. From this study, it was possible to conclude that in the case of diluted samples in denaturing buffers, the use of cold acetone as precipitation protocol is more favourable than the use of <span class="hlt">TCA</span>/acetone in terms of reproducibility in protein recovery and number of identified and quantified proteins. Furthermore, the reproducibility in relative quantification of the proteins is even higher in samples precipitated with acetone compared with the original sample. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.A51P0336P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.A51P0336P"><span>Tropical Cyclone Evolution and Water and Energy <span class="hlt">Fluxes</span>: A Hurricane Katrina Case Study</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pinheiro, M. C.; Zhou, Y.</p> <p>2015-12-01</p> <p>Tropical cyclones are a highly destructive force of nature, characterized by extreme precipitation levels and wind speeds and heavy flooding. There are concerns that climate change will cause changes in the intensity and frequency of tropical cyclones. Therefore, the quantification of the water and energy <span class="hlt">fluxes</span> that occur during a tropical cyclone's life <span class="hlt">cycle</span> are important for anticipating the magnitude of damages that are likely to occur. This study used HURDAT2 storm track information and data from the satellite-derived Sea<span class="hlt">Flux</span> and TRMM products to determine changes in precipitation, wind, and latent and sensible heat throughout the life <span class="hlt">cycle</span> of Hurricane Katrina. The variables were examined along and around the storm track, taking averages both at stationary 5x5 degree boxes and within the instantaneous hurricane domain. Analysis focused on contributions of convergence and latent heat to the storm evolution and examined how the total <span class="hlt">flux</span> was related to the storm intensity. Certain features, such as the eye, were not resolved due to the data resolution, but the data captures the general trend of enhanced <span class="hlt">flux</span> levels that are due to the storm's presence. Analysis also included examination of the water and energy budgets as related to convergence and the sensible and latent heat <span class="hlt">fluxes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B51I1939S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B51I1939S"><span>How interactions between top-down and bottom-up controls on carbon <span class="hlt">cycling</span> affect <span class="hlt">fluxes</span> within and from lakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sadro, S.; Piovia-Scott, J.; Nelson, C.; Sickman, J. O.; Knapp, R.</p> <p>2017-12-01</p> <p>While the role of inland waters in global carbon <span class="hlt">cycling</span> has grown clearer in recent decades, the extent to which top-down and bottom-up mechanisms interact to regulate dynamics at the catchment scale is not well understood. The degree to which lakes process, export, or store terrestrial carbon is influenced by hydrological variability, variation in the magnitude of terrestrial organic matter (t-OM) entering a system, the efficiency with which such material is metabolized by bacterioplankton, the extent to which it is incorporated into secondary consumer biomass, and by the effects of food-web structure, such as the presence or absence of top predators. However, how these processes interact to mediate carbon <span class="hlt">fluxes</span> between terrestrial, aquatic, and atmospheric reservoirs remains unclear. We develop a conceptual model that explores how interactions among these factors ultimately affects carbon dynamics using data from lakes located in the Sierra Nevada mountains of California. The Sierra are an excellent system for studies of carbon <span class="hlt">cycling</span> because elevation-induced landscape gradients in soil development and vegetation cover provide large natural variation in terrestrial inputs to lakes, while variation in confounding factors such as lake morphometry or trophic state is comparatively small. Dissolved organic carbon concentrations increase 100 fold in lakes spanning the alpine to montane elevation gradient found in the Sierra, and fluorescence characteristics reflect an increasingly terrestrial signature with decreasing elevation. Bacterioplankton make up a large proportion of total ecosystem metabolism in these systems, and their metabolic efficiency is tightly coupled to the composition of dissolved organic matter. Stable isotope food web data (δ13C, Δ14C, and δ2H) and measurements of pCO2 from lakes indicate the magnitude of allochthony, rates if carbon <span class="hlt">cycling</span>, and ecosystem heterotrophy all increase with the increasingly terrestrial signature of dissolved</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/10197314','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/10197314"><span>Fast <span class="hlt">Flux</span> Test Facility thermal and pressure transient events during <span class="hlt">Cycle</span> 11</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Ahrens, D. M.</p> <p>1992-03-01</p> <p>This report documents the thermal and pressure transients experienced by the Reactor Heat Transport System (RHTS) during <span class="hlt">Cycle</span> 11 which included <span class="hlt">Cycles</span> 11A, 11B-1, 11B-2 and 11C (i.e. 4 startups and 4 shutdowns). <span class="hlt">Cycle</span> 11 consisted of a refueling period that began on March 14, 1989 and power operation which began on May 3, 1989 and ended on October 27, 1990. Transients resulted from secondary pump starts/stops while at refueling conditions. The major causes of transients at power were five unplanned reactor scrams from 100% power and problems with Loop 2 DHX Fan Controls During 11A.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11054649','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11054649"><span>Selective modification of the pyruvate dehydrogenase kinase isoform profile in skeletal muscle in hyperthyroidism: implications for the regulatory impact of glucose on fatty acid oxidation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sugden, M C; Lall, H S; Harris, R A; Holness, M J</p> <p>2000-11-01</p> <p>The pyruvate dehydrogenase kinases (PDK1-4) regulate glucose oxidation through inhibitory phosphorylation of the pyruvate dehydrogenase complex (PDC). Immunoblot analysis with antibodies raised against recombinant PDK isoforms demonstrated changes in PDK isoform expression in response to experimental hyperthyroidism (100 microg/100 g body weight; 3 days) that was selective for fast-twitch vs slow-twitch skeletal muscle in that PDK2 expression was increased in the fast-twitch skeletal muscle (the anterior tibialis) (by 1. 6-fold; P<0.05) but not in the slow-twitch muscle (the soleus). PDK4 protein expression was increased by experimental hyperthyroidism in both muscle types, there being a greater response in the anterior tibialis (4.2-fold increase; P<0.05) than in the soleus (3.2-fold increase; P<0.05). The hyperthyroidism-associated up-regulation of PDK4 expression was observed in conjunction with suppression of skeletal-muscle PDC activity, but not suppression of glucose uptake/phosphorylation, as measured in vivo in conscious unrestrained rats (using the 2-[(3)H]deoxyglucose technique). We propose that increased PDK isoform expression contributes to the pathology of hyperthyroidism and to PDC inactivation by facilitating the operation of the glucose --> lactate --> glucose (Cori) and glucose --> alanine --> glucose <span class="hlt">cycles</span>. We also propose that enhanced relative expression of the pyruvate-insensitive PDK isoform (PDK4) in skeletal muscle in hyperthyroidism uncouples glycolytic <span class="hlt">flux</span> from pyruvate oxidation, sparing pyruvate for non-oxidative entry into the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span>, and thereby supporting entry of acetyl-CoA (derived from fatty acid oxidation) into the <span class="hlt">TCA</span> <span class="hlt">cycle</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890002945','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890002945"><span>Three-dimensional multigrid algorithms for the <span class="hlt">flux</span>-split Euler equations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Anderson, W. Kyle; Thomas, James L.; Whitfield, David L.</p> <p>1988-01-01</p> <p>The Full Approximation Scheme (FAS) multigrid method is applied to several implicit <span class="hlt">flux</span>-split algorithms for solving the three-dimensional Euler equations in a body fitted coordinate system. Each of the splitting algorithms uses a variation of approximate factorization and is implemented in a finite volume formulation. The algorithms are all vectorizable with little or no scalar computation required. The <span class="hlt">flux</span> vectors are split into upwind components using both the splittings of Steger-Warming and Van Leer. The stability and smoothing rate of each of the schemes are examined using a Fourier analysis of the complete system of equations. Results are presented for three-dimensional subsonic, transonic, and supersonic flows which demonstrate substantially improved convergence rates with the multigrid algorithm. The influence of using both a V-<span class="hlt">cycle</span> and a W-<span class="hlt">cycle</span> on the convergence is examined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29170969','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29170969"><span>Two-Scale 13C Metabolic <span class="hlt">Flux</span> Analysis for Metabolic Engineering.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ando, David; Garcia Martin, Hector</p> <p>2018-01-01</p> <p>Accelerating the Design-Build-Test-Learn (DBTL) <span class="hlt">cycle</span> in synthetic biology is critical to achieving rapid and facile bioengineering of organisms for the production of, e.g., biofuels and other chemicals. The Learn phase involves using data obtained from the Test phase to inform the next Design phase. As part of the Learn phase, mathematical models of metabolic <span class="hlt">fluxes</span> give a mechanistic level of comprehension to cellular metabolism, isolating the principle drivers of metabolic behavior from the peripheral ones, and directing future experimental designs and engineering methodologies. Furthermore, the measurement of intracellular metabolic <span class="hlt">fluxes</span> is specifically noteworthy as providing a rapid and easy-to-understand picture of how carbon and energy flow throughout the cell. Here, we present a detailed guide to performing metabolic <span class="hlt">flux</span> analysis in the Learn phase of the DBTL <span class="hlt">cycle</span>, where we show how one can take the isotope labeling data from a 13 C labeling experiment and immediately turn it into a determination of cellular <span class="hlt">fluxes</span> that points in the direction of genetic engineering strategies that will advance the metabolic engineering process.For our modeling purposes we use the Joint BioEnergy Institute (JBEI) Quantitative Metabolic Modeling (jQMM) library, which provides an open-source, python-based framework for modeling internal metabolic <span class="hlt">fluxes</span> and making actionable predictions on how to modify cellular metabolism for specific bioengineering goals. It presents a complete toolbox for performing different types of <span class="hlt">flux</span> analysis such as <span class="hlt">Flux</span> Balance Analysis, 13 C Metabolic <span class="hlt">Flux</span> Analysis, and it introduces the capability to use 13 C labeling experimental data to constrain comprehensive genome-scale models through a technique called two-scale 13 C Metabolic <span class="hlt">Flux</span> Analysis (2S- 13 C MFA) [1]. In addition to several other capabilities, the jQMM is also able to predict the effects of knockouts using the MoMA and ROOM methodologies. The use of the jQMM library is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ECSS...95...59L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ECSS...95...59L"><span>Tidal variability in benthic silicic acid <span class="hlt">fluxes</span> and microphytobenthos uptake in intertidal sediment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Leynaert, Aude; Longphuirt, Sorcha Ní; An, Soonmo; Lim, Jae-Hyun; Claquin, Pascal; Grall, Jacques; Kwon, Bong Oh; Koh, Chul Hwan</p> <p>2011-11-01</p> <p>Silicic acid (DSi) benthic <span class="hlt">fluxes</span> play a major role in the benthic-pelagic coupling of coastal ecosystems. They can sustain microphytobenthos (MPB) development at the water-sediment interface and support pelagic diatoms when river DSi inputs decrease. DSi benthic <span class="hlt">fluxes</span> have been studied at the seasonal scale but little is known about their dial variations. This study measured the amplitude of such variations in an intertidal area over an entire tidal <span class="hlt">cycle</span> by following the alteration of DSi pore water concentrations at regular intervals over the flood/ebb period. Furthermore we independently estimated the potential DSi uptake by benthic diatoms and compared it to the variations of DSi pore water concentrations and <span class="hlt">fluxes</span>. The microphytobenthos DSi demand was estimated from primary production measurements on cells extracted from the sediment. There were large changes in DSi pore water concentration and a prominent effect of tidal pumping: the DSi flushed out from the sediment at rising tide, occurs in a very short period of time, but plays a far more important role in fueling the ecosystem (800 μmol-Si m -2 d -1), than diffusive <span class="hlt">fluxes</span> occurring throughout the rest of the tidal <span class="hlt">cycle</span> (2 μmol-Si m -2 d -1). This process is not, to our knowledge, currently considered when describing the DSi <span class="hlt">cycling</span> of intertidal sediments. Moreover, there was a large potential MPB requirement for DSi (812 μmol-Si m -2 d -1), similar to the advective flow periodically pumped by the incoming tide, and largely exceeded benthic diffusive <span class="hlt">fluxes</span>. However, this DSi uptake by benthic diatoms is almost undetectable given the variation of DSi concentration profiles within the sediment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhST..170a4007B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhST..170a4007B"><span>Comparison of heat <span class="hlt">flux</span> measurement techniques during the DIII-D metal ring campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barton, J. L.; Nygren, R. E.; Unterberg, E. A.; Watkins, J. G.; Makowski, M. A.; Moser, A.; Rudakov, D. L.; Buchenauer, D.</p> <p>2017-12-01</p> <p>The heat <span class="hlt">fluxes</span> expected in the ITER divertor raise concerns about the damage tolerances of tungsten, especially due to thermal transients caused by edge localized modes (ELMs) as well as frequent temperature <span class="hlt">cycling</span> from high to low extremes. Therefore we are motivated to understand the heat <span class="hlt">flux</span> conditions that can cause not only enhanced erosion but also bulk thermo-mechanical damage to a tungsten divertor. For the metal ring campaign in DIII-D, tungsten-coated TZM tile inserts were installed making two toroidal arrays of metal tile inserts in the lower divertor. This study examines the deposited heat <span class="hlt">flux</span> on these rings with embedded thermocouples (TCs) sampling at 10 kHz and compares them to Langmuir probe (LP) and infrared thermography (IRTV) heat <span class="hlt">flux</span> measurements. We see agreement of the TC, LP, and IRTV data within 20% of the heat <span class="hlt">flux</span> averaged over the entire discharge, and that all three diagnostics suggest parallel heat <span class="hlt">flux</span> at the OSP location increases linearly with input heating power. The TC and LP heat <span class="hlt">flux</span> time traces during the discharge trend together during large changes to the average heat <span class="hlt">flux</span>. By subtracting the LP measured inter-ELM heat <span class="hlt">flux</span> from TC data, using a rectangular ELM energy pulse shape, and taking the relative size and duration of each ELM from {{D}}α measurements, we extract the ELM heat <span class="hlt">fluxes</span> from TC data. This over-estimates the IRTV measured ELM heat <span class="hlt">fluxes</span> by a factor of 1.9, and could be due to the simplicity of the TC heat <span class="hlt">flux</span> model and the assumed ELM energy pulse shape. ELM heat <span class="hlt">fluxes</span> deposited on the inserts are used to model tungsten erosion in this campaign. These TC ELM heat <span class="hlt">flux</span> estimates are used in addition to IRTV, especially in cases where the IRTV view to the metal ring is obstructed. We observe that some metal inserts were deformed due to exposed leading edges. The thermal conditions on these inserts are investigated with the thermal modeling code ABAQUS using our heat <span class="hlt">flux</span> measurements when these edges</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22654142-coronal-dynamic-activities-declining-phase-solar-cycle','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22654142-coronal-dynamic-activities-declining-phase-solar-cycle"><span>CORONAL DYNAMIC ACTIVITIES IN THE DECLINING PHASE OF A SOLAR <span class="hlt">CYCLE</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Jang, Minhwan; Choe, G. S.; Woods, T. N.</p> <p>2016-12-10</p> <p>It has been known that some solar activity indicators show a double-peak feature in their evolution through a solar <span class="hlt">cycle</span>, which is not conspicuous in sunspot number. In this Letter, we investigate the high solar dynamic activity in the declining phase of the sunspot <span class="hlt">cycle</span> by examining the evolution of polar and low-latitude coronal hole (CH) areas, splitting and merging events of CHs, and coronal mass ejections (CMEs) detected by SOHO /LASCO C3 in solar <span class="hlt">cycle</span> 23. Although the total CH area is at its maximum near the sunspot minimum, in which polar CHs prevail, it shows a comparable secondmore » maximum in the declining phase of the <span class="hlt">cycle</span>, in which low-latitude CHs are dominant. The events of CH splitting or merging, which are attributed to surface motions of magnetic <span class="hlt">fluxes</span>, are also mostly populated in the declining phase of the <span class="hlt">cycle</span>. The far-reaching C3 CMEs are also overpopulated in the declining phase of the <span class="hlt">cycle</span>. From these results we suggest that solar dynamic activities due to the horizontal surface motions of magnetic <span class="hlt">fluxes</span> extend far in the declining phase of the sunspot <span class="hlt">cycle</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920064052&hterms=TENS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DTENS','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920064052&hterms=TENS&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DTENS"><span>Solar-cosmic-ray <span class="hlt">fluxes</span> during the last ten million years</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reedy, Robert C.; Marti, Kurt</p> <p>1991-01-01</p> <p>The <span class="hlt">fluxes</span> of energetic (E is greater than or approximately equal to 10 MeV) solar particles in the vicinity of the earth in the past can be determined from nuclides that they produced in the top centimeter of lunar rocks. Activity-vs-depth profiles of short-lived radioactivities measured in the top centimeter of lunar rocks agree with profiles calculated with directly measured solar-proton <span class="hlt">fluxes</span> since about 1965 and were used with indirect observations to get solar-proton <span class="hlt">fluxes</span> back to 1956. Lunar-rock profiles for long-lived radionuclides have been used to infer solar-proton <span class="hlt">fluxes</span> averaged over several time periods in the past. New results are reported for solar-proton-produced Kr-81 measured in lunar rock 68815. Activities of 76,000-yr Ni-59 can be used to get <span class="hlt">fluxes</span> of solar alpha particles averaged over the last 100,000 yr. The average solar-proton <span class="hlt">fluxes</span> in the past are not greatly different from those observed during the last three 11-yr solar <span class="hlt">cycles</span>. The work that needs to be done to determine more and better <span class="hlt">fluxes</span> of energetic particles from the sun in the past is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4480687','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4480687"><span>Glutamate and asparagine cataplerosis underlie glutamine addiction in melanoma</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ratnikov, Boris; Aza-Blanc, Pedro; Ronai, Ze'ev A.; Smith, Jeffrey W.; Osterman, Andrei L.; Scott, David A.</p> <p>2015-01-01</p> <p>Glutamine dependence is a prominent feature of cancer metabolism, and here we show that melanoma cells, irrespective of their oncogenic background, depend on glutamine for growth. A quantitative audit of how carbon from glutamine is used showed that <span class="hlt">TCA-cycle</span>-derived glutamate is, in most melanoma cells, the major glutamine-derived cataplerotic output and product of glutaminolysis. In the absence of glutamine, <span class="hlt">TCA</span> <span class="hlt">cycle</span> metabolites were liable to depletion through aminotransferase-mediated α-ketoglutarate-to-glutamate conversion and glutamate secretion. Aspartate was an essential cataplerotic output, as melanoma cells demonstrated a limited capacity to salvage external aspartate. Also, the absence of asparagine increased the glutamine requirement, pointing to vulnerability in the aspartate-asparagine biosynthetic pathway within melanoma metabolism. In contrast to melanoma cells, melanocytes could grow in the absence of glutamine. Melanocytes use more glutamine for protein synthesis rather than secreting it as glutamate and are less prone to loss of glutamate and <span class="hlt">TCA</span> <span class="hlt">cycle</span> metabolites when starved of glutamine. PMID:25749035</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4785096','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4785096"><span>Environment impacts the metabolic dependencies of Ras-driven non-small cell lung cancer</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Davidson, Shawn M.; Papagiannakopoulos, Thales; Olenchock, Benjamin A.; Heyman, Julia E.; Keibler, Mark A.; Luengo, Alba; Bauer, Matthew R.; Jha, Abhishek K.; O’Brien, James P.; Pierce, Kerry A.; Gui, Dan Y.; Sullivan, Lucas B.; Wasylenko, Thomas M.; Subbaraj, Lakshmipriya; Chin, Christopher R.; Stephanopolous, Gregory; Mott, Bryan T.; Jacks, Tyler; Clish, Clary B.; Vander Heiden, Matthew G.</p> <p>2016-01-01</p> <p>SUMMARY Cultured cells convert glucose to lactate and glutamine is the major source of tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> carbon, but whether the same metabolic phenotype is found in tumors is less studied. We infused mice with lung cancers with isotope-labeled glucose or glutamine and compared the fate of these nutrients in tumor and normal tissue. As expected, lung tumors exhibit increased lactate production from glucose. However, glutamine utilization by both lung tumors and normal lung was minimal, with lung tumors showing increased glucose contribution to the <span class="hlt">TCA</span> <span class="hlt">cycle</span> relative to normal lung tissue. Deletion of enzymes involved in glucose oxidation demonstrates that glucose carbon contribution to the <span class="hlt">TCA</span> <span class="hlt">cycle</span> is required for tumor formation. These data suggest that understanding nutrient utilization by tumors can predict metabolic dependencies of cancers in vivo. Furthermore, these data argue that the in vivo environment is an important determinant of the metabolic phenotype of cancer cells. PMID:26853747</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18638551','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18638551"><span>Ion <span class="hlt">fluxes</span> and neurotransmitters signaling in neural development.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Andäng, Michael; Lendahl, Urban</p> <p>2008-06-01</p> <p>The brain develops and functions in a complex ionic milieu, which is a prerequisite for neurotransmitter function and neuronal signaling. Neurotransmitters and ion <span class="hlt">fluxes</span> are, however, important not only in neuronal signaling, but also in the control of neural differentiation, and in this review, we highlight the recent advances in our understanding of how the gamma-amino butyric acid (GABA) neurotransmitter and ion <span class="hlt">fluxes</span> are relevant for cell <span class="hlt">cycle</span> control and neural differentiation. Conversely, proteins previously associated with ion transport across membranes have been endowed with novel ion-independent functions, and we discuss this in the context of gap junctions in cell adhesion and of the neuron-specific K(+)-Cl(-) cotransporter KCC2 in dendritic spine development. Collectively, these findings provide a richer and more complex picture of when ion <span class="hlt">fluxes</span> are needed in neural development and when they are not.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.B53C0476C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.B53C0476C"><span>Constraining land carbon <span class="hlt">cycle</span> process understanding with observations of atmospheric CO2 variability</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Collatz, G. J.; Kawa, S. R.; Liu, Y.; Zeng, F.; Ivanoff, A.</p> <p>2013-12-01</p> <p>We evaluate our understanding of the land biospheric carbon <span class="hlt">cycle</span> by benchmarking a model and its variants to atmospheric CO2 observations and to an atmospheric CO2 inversion. Though the seasonal <span class="hlt">cycle</span> in CO2 observations is well simulated by the model (RMSE/standard deviation of observations <0.5 at most sites north of 15N and <1 for Southern Hemisphere sites) different model setups suggest that the CO2 seasonal <span class="hlt">cycle</span> provides some constraint on gross photosynthesis, respiration, and fire <span class="hlt">fluxes</span> revealed in the amplitude and phase at northern latitude sites. CarbonTracker inversions (CT) and model show similar phasing of the seasonal <span class="hlt">fluxes</span> but agreement in the amplitude varies by region. We also evaluate interannual variability (IAV) in the measured atmospheric CO2 which, in contrast to the seasonal <span class="hlt">cycle</span>, is not well represented by the model. We estimate the contributions of biospheric and fire <span class="hlt">fluxes</span>, and atmospheric transport variability to explaining observed variability in measured CO2. Comparisons with CT show that modeled IAV has some correspondence to the inversion results >40N though <span class="hlt">fluxes</span> match poorly at regional to continental scales. Regional and global fire emissions are strongly correlated with variability observed at northern flask sample sites and in the global atmospheric CO2 growth rate though in the latter case fire emissions anomalies are not large enough to account fully for the observed variability. We discuss remaining unexplained variability in CO2 observations in terms of the representation of <span class="hlt">fluxes</span> by the model. This work also demonstrates the limitations of the current network of CO2 observations and the potential of new denser surface measurements and space based column measurements for constraining carbon <span class="hlt">cycle</span> processes in models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16130792','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16130792"><span>Highly selective solid-phase extraction and large volume injection for the robust gas chromatography-mass spectrometric analysis of <span class="hlt">TCA</span> and TBA in wines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Insa, S; Anticó, E; Ferreira, V</p> <p>2005-09-30</p> <p>A reliable solid-phase extraction (SPE) method for the simultaneous determination of 2,4,6-trichloroanisole (<span class="hlt">TCA</span>) and 2,4,6-tribromoanisole (TBA) in wines has been developed. In the proposed procedure 50 mL of wine are extracted in a 1 mL cartridge filled with 50 mg of LiChrolut EN resins. Most wine volatiles are washed up with 12.5 mL of a water:methanol solution (70%, v/v) containing 1% of NaHCO3. Analytes are further eluted with 0.6 mL of dichloromethane. A 40 microL aliquot of this extract is directly injected into a PTV injector operated in the solvent split mode, and analysed by gas chromatography (GC)-ion trap mass spectrometry using the selected ion storage mode. The solid-phase extraction, including sample volume and rinsing and elution solvents, and the large volume GC injection have been carefully evaluated and optimized. The resulting method is precise (RSD (%) < 6% at 100 ng L(-1)), sensitive (LOD were 0.2 and 0.4 ng/L for <span class="hlt">TCA</span> and TBA, respectively), robust (the absolute recoveries of both analytes are higher than 80% and consistent wine to wine) and friendly to the GC-MS system (the extract is clean, simple and free from non-volatiles).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1038495-imprint-surface-fluxes-transport-variations-total-column-carbon-dioxide','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1038495-imprint-surface-fluxes-transport-variations-total-column-carbon-dioxide"><span>The imprint of surface <span class="hlt">fluxes</span> and transport on variations in total column carbon dioxide</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Keppel-Aleks, G; Wennberg, PO; Washenfelder, RA</p> <p>2012-01-01</p> <p>New observations of the vertically integrated CO{sub 2} mixing ratio, <CO{sub 2}>, from ground-based remote sensing show that variations in <CO{sub 2}> are primarily determined by large-scale <span class="hlt">flux</span> patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local <span class="hlt">fluxes</span>. Observations of both <CO{sub 2}> and CO{sub 2} concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in <CO{sub 2}> in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface <span class="hlt">fluxes</span> on atmospheric CO{sub 2}, these synoptic-scale variationsmore » provide useful information that can be used to reveal the meridional <span class="hlt">flux</span> distribution. We estimate the meridional gradient in <CO{sub 2}> from covariations in <CO{sub 2}> and potential temperature, {theta}, a dynamical tracer, on synoptic timescales to evaluate surface <span class="hlt">flux</span> estimates commonly used in carbon <span class="hlt">cycle</span> models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric <span class="hlt">fluxes</span> underestimate both the <CO{sub 2}> seasonal <span class="hlt">cycle</span> amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal <span class="hlt">fluxes</span> better fit the observations. Our simulations suggest that climatological mean CASA <span class="hlt">fluxes</span> underestimate boreal growing season NEE (between 45-65{sup o} N) by {approx}40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BGeo....9..875K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BGeo....9..875K"><span>The imprint of surface <span class="hlt">fluxes</span> and transport on variations in total column carbon dioxide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keppel-Aleks, G.; Wennberg, P. O.; Washenfelder, R. A.; Wunch, D.; Schneider, T.; Toon, G. C.; Andres, R. J.; Blavier, J.-F.; Connor, B.; Davis, K. J.; Desai, A. R.; Messerschmidt, J.; Notholt, J.; Roehl, C. M.; Sherlock, V.; Stephens, B. B.; Vay, S. A.; Wofsy, S. C.</p> <p>2012-03-01</p> <p>New observations of the vertically integrated CO2 mixing ratio, ⟨CO2⟩, from ground-based remote sensing show that variations in CO2⟩ are primarily determined by large-scale <span class="hlt">flux</span> patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large-scale and local <span class="hlt">fluxes</span>. Observations of both ⟨CO2⟩ and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in ⟨CO2⟩ in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface <span class="hlt">fluxes</span> on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional <span class="hlt">flux</span> distribution. We estimate the meridional gradient in ⟨CO2⟩ from covariations in ⟨CO2⟩ and potential temperature, θ, a dynamical tracer, on synoptic timescales to evaluate surface <span class="hlt">flux</span> estimates commonly used in carbon <span class="hlt">cycle</span> models. We find that simulations using Carnegie Ames Stanford Approach (CASA) biospheric <span class="hlt">fluxes</span> underestimate both the ⟨CO2⟩ seasonal <span class="hlt">cycle</span> amplitude throughout the Northern Hemisphere midlatitudes and the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal <span class="hlt">fluxes</span> better fit the observations. Our simulations suggest that climatological mean CASA <span class="hlt">fluxes</span> underestimate boreal growing season NEE (between 45-65° N) by ~40%. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMSH12A..01U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMSH12A..01U"><span>AFT: Extending Solar <span class="hlt">Cycle</span> Prediction with Data Assimilation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Upton, L.; Hathaway, D. H.</p> <p>2017-12-01</p> <p>The Advective <span class="hlt">Flux</span> Transport (AFT) model is an innovative surface <span class="hlt">flux</span> transport model that simulates the evolution of the radial magnetic field on the surface of the Sun. AFT was designed to be as realistic as possible by 1: incorporating the observed surface flows (meridional flow, differential rotation, and an explicit evolving convective pattern) and by 2: using data assimilation to incorporate the observed magnetic fields directly from line-of-sight (LOS) magnetograms. AFT has proven to be successful in simulating the evolution of the surface magnetic fields on both short time scales (days-weeks) as well as for long time scales (years). In particular, AFT has been shown to accurately predict the evolution of the Sun's dipolar magnetic field 3-5 years in advance. Since the Sun's polar magnetic field strength at solar <span class="hlt">cycle</span> minimum is the best indicator of the amplitude of the next <span class="hlt">cycle</span>, this has in turn extended our ability to make solar <span class="hlt">cycle</span> predictions to 3-5 years before solar minimum occurs. Here, we will discuss some of the challenges of implementing data assimilation into AFT. We will also discuss the role of data assimilation in advancing solar <span class="hlt">cycle</span> predictive capability.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRD..122.4829R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRD..122.4829R"><span>An intercomparison and validation of satellite-based surface radiative energy <span class="hlt">flux</span> estimates over the Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riihelä, Aku; Key, Jeffrey R.; Meirink, Jan Fokke; Kuipers Munneke, Peter; Palo, Timo; Karlsson, Karl-Göran</p> <p>2017-05-01</p> <p>Accurate determination of radiative energy <span class="hlt">fluxes</span> over the Arctic is of crucial importance for understanding atmosphere-surface interactions, melt and refreezing <span class="hlt">cycles</span> of the snow and ice cover, and the role of the Arctic in the global energy budget. Satellite-based estimates can provide comprehensive spatiotemporal coverage, but the accuracy and comparability of the existing data sets must be ascertained to facilitate their use. Here we compare radiative <span class="hlt">flux</span> estimates from Clouds and the Earth's Radiant Energy System (CERES) Synoptic 1-degree (SYN1deg)/Energy Balanced and Filled, Global Energy and Water <span class="hlt">Cycle</span> Experiment (GEWEX) surface energy budget, and our own experimental <span class="hlt">Flux</span>Net / Satellite Application Facility on Climate Monitoring cLoud, Albedo and RAdiation (CLARA) data against in situ observations over Arctic sea ice and the Greenland Ice Sheet during summer of 2007. In general, CERES SYN1deg <span class="hlt">flux</span> estimates agree best with in situ measurements, although with two particular limitations: (1) over sea ice the upwelling shortwave <span class="hlt">flux</span> in CERES SYN1deg appears to be underestimated because of an underestimated surface albedo and (2) the CERES SYN1deg upwelling longwave <span class="hlt">flux</span> over sea ice saturates during midsummer. The Advanced Very High Resolution Radiometer-based GEWEX and <span class="hlt">Flux</span>Net-CLARA <span class="hlt">flux</span> estimates generally show a larger range in retrieval errors relative to CERES, with contrasting tendencies relative to each other. The largest source of retrieval error in the <span class="hlt">Flux</span>Net-CLARA downwelling shortwave <span class="hlt">flux</span> is shown to be an overestimated cloud optical thickness. The results illustrate that satellite-based <span class="hlt">flux</span> estimates over the Arctic are not yet homogeneous and that further efforts are necessary to investigate the differences in the surface and cloud properties which lead to disagreements in <span class="hlt">flux</span> retrievals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JAsGe...7...15H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JAsGe...7...15H"><span>Forecasting the peak of the present solar activity <span class="hlt">cycle</span> 24</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hamid, R. H.; Marzouk, B. A.</p> <p>2018-06-01</p> <p>Solar forecasting of the level of sun Activity is very important subject for all space programs. Most predictions are based on the physical conditions prevailing at or before the solar <span class="hlt">cycle</span> minimum preceding the maximum in question. Our aim is to predict the maximum peak of <span class="hlt">cycle</span> 24 using precursor techniques in particular those using spotless event, geomagnetic aamin. index and solar <span class="hlt">flux</span> F10.7. Also prediction of exact date of the maximum (Tr) is taken in consideration. A study of variation over previous spotless event for <span class="hlt">cycles</span> 7-23 and that for even <span class="hlt">cycles</span> (8-22) are carried out for the prediction. Linear correlation between maximum of solar <span class="hlt">cycles</span> (RM) and spotless event around the preceding minimum gives R24t = 88.4 with rise time Tr = 4.6 years. For the even <span class="hlt">cycles</span> R24E = 77.9 with rise time Tr = 4.5 y's. Based on the average aamin. index for <span class="hlt">cycles</span> (12-23), we estimate the expected amplitude for <span class="hlt">cycle</span> 24 to be Raamin = 99.4 and 98.1 with time rise of Traamin = 4.04 & 4.3 years for both the total and even <span class="hlt">cycles</span> in consecutive. The application of the data of solar <span class="hlt">flux</span> F10.7 which cover only <span class="hlt">cycles</span> (19-23) was taken in consideration and gives predicted maximum amplitude R24 10.7 = 126 with rise time Tr107 = 3.7 years, which are over estimation. Our result indicating to somewhat weaker of <span class="hlt">cycle</span> 24 as compared to <span class="hlt">cycles</span> 21-23.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110008740','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110008740"><span>Monitoring Delamination of Thermal Barrier Coatings During Interrupted High-Heat-<span class="hlt">Flux</span> Laser Testing using Luminescence Imaging</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Eldridge, Jeffrey I.; Zhu, Dongming; Wolfe, Douglas E.</p> <p>2011-01-01</p> <p>This presentation showed progress made in extending luminescence-base delamination monitoring to TBCs exposed to high heat <span class="hlt">fluxes</span>, which is an environment that much better simulates actual turbine engine conditions. This was done by performing upconversion luminescence imaging during interruptions in laser testing, where a high-power CO2 laser was employed to create the desired heat <span class="hlt">flux</span>. Upconverison luminescence refers to luminescence where the emission is at a higher energy (shorter wavelength) than the excitation. Since there will be negligible background emission at higher energies than the excitation, this methods produces superb contrast. Delamination contrast is produced because both the excitation and emission wavelengths are reflected at delamination cracks so that substantially higher luminescence intensity is observed in regions containing delamination cracks. Erbium was selected as the dopant for luminescence specifically because it exhibits upconversion luminescence. The high power CO2 10.6 micron wavelength laser facility at NASA GRC was used to produce the heat <span class="hlt">flux</span> in combination with forced air backside cooling. Testing was performed at a lower (95 W/sq cm) and higher (125 W/sq cm) heat <span class="hlt">flux</span> as well as furnace <span class="hlt">cycling</span> at 1163C for comparison. The lower heat <span class="hlt">flux</span> showed the same general behavior as furnace <span class="hlt">cycling</span>, a gradual, "spotty" increase in luminescence associated with debond progression; however, a significant difference was a pronounced incubation period followed by acceleration delamination progression. These results indicate that extrapolating behavior from furnace <span class="hlt">cycling</span> measurements will grossly overestimate remaining life under high heat <span class="hlt">flux</span> conditions. The higher heat <span class="hlt">flux</span> results were not only accelerated, but much different in character. Extreme bond coat rumpling occurred, and delamination propagation extended over much larger areas before precipitating macroscopic TBC failure. This indicates that under the higher heat <span class="hlt">flux</span> (and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..11.9538S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..11.9538S"><span>Eddy <span class="hlt">Flux</span> Tower in Ankasa Park : a new facility for the study of the carbon <span class="hlt">cycle</span> of primary tropical forests in Africa</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stefani, P.; Belelli Marchesini, L.; Consalvo, C.; Forgione, A.; Bombelli, A.; Grieco, E.; Mazzenga, F.; Vittorini, E.; Papale, D.; Valentini, R.</p> <p>2009-04-01</p> <p>An Eddy Covariance station for the monitoring of CO2 and energy <span class="hlt">fluxes</span> over a primary tropical forest in Ghana is operative as part of the CarboAfrica eddy covariance network. The facility, located in the Ankasa Conservation area (05° 16' 11.2''N; 02° 41' 41.55'' W), includes a 65 m tall steel tower equipped with a system enabling the measurements of <span class="hlt">fluxes</span> at the top of the structure, of CO2, air temperature and humidity along a vertical profile and of relevant physical parameters of the forest ecosystem. The Ankasa <span class="hlt">flux</span> tower is the first in the African continent collecting data on CO2 exchanges over a tropical primary forest, and from its activity a breakthrough in the understanding of the carbon <span class="hlt">cycling</span> in this kind of environment is expected. Moreover the knowledge gained on the carbon balance of this primary forest can be used as a reference to thoroughly evaluate the impacts of deforestation, beyond the decrease of carbon stocks. The analysis of preliminary data collected in the first week of August 2008 shows a daily uptake of 1.33±0.73 gC m-2 d-1 (mean±s.e.) and highlights the large magnitude of the storage of CO2 within the canopy space causing a discrepancy between the CO2 <span class="hlt">flux</span> observed at the top of the tower (Fc) and the overall net ecosystem exchange (NEE). During night-time NEE reveals a respiration rate up to 4 times higher than Fc while in the first hours after dawn assimilation of CO2 in the canopy space is sensed at the top level of measurement with about 3 hours of delay. Associated to the tower site, a field campaign to estimate biomass and biodiversity was carried out. Two transects were demarcated for a total surface of 2 ha. Each transect measuring 1000 m x 10 m, they were divided into 10 subplots and intersected each other at the centre and they were perpendicular to one another. The point of intersection is located on the tower where they are located all the instrumentation for monitoring carbon <span class="hlt">fluxes</span>. All the data is still being</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018SuScT..31c5001S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018SuScT..31c5001S"><span><span class="hlt">Flux</span> trapping in multi-loop SQUIDs and its impact on SQUID-based absolute magnetometry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schönau, T.; Zakosarenko, V.; Schmelz, M.; Anders, S.; Meyer, H.-G.; Stolz, R.</p> <p>2018-07-01</p> <p>The effect of <span class="hlt">flux</span> trapping on the <span class="hlt">flux</span>-voltage characteristics of multi-loop SQUID magnetometers was investigated by means of repeated cool-down <span class="hlt">cycles</span> in a stepwise increased magnetic background field. For a SQUID with N parallel loops, N different <span class="hlt">flux</span> offsets, each separated by {{{Φ }}}0/N, were observed even in zero magnetic field. These <span class="hlt">flux</span> offsets further split into a so called fine structure, which can be explained by minor asymmetries in the SQUID design. The observed results are discussed with particular regard to their impact on the previously presented absolute SQUID cascade vector magnetometer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70185710','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70185710"><span>Variability and prediction of freshwater and nitrate <span class="hlt">fluxes</span> for the Louisiana-Texas shelf: Mississippi and Atchafalaya River source functions</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Bratkovich, A.; Dinnel, S.P.; Goolsby, D.A.</p> <p>1994-01-01</p> <p>Time histories of riverine water discharge, nitrate concentration, and nitrate, <span class="hlt">flux</span> have been analyzed for the Mississippi and Atchafalaya rivers. Results indicate that water discharge variability is dominated by the annual <span class="hlt">cycle</span> and shorter-time-scale episodic events presumably associated with snowmelt runoff and spring or summer rains. Interannual variability in water discharge is relatively small compared to the above. In contrast, nitrate concentration exhibits strongest variability at decadal time scales. The interannual variability is not monotonic but more complicated in structure. Weak covariability between water discharge and nitrate concentration leads to a relatively “noisy” nitrate <span class="hlt">flux</span> signal. Nitrate <span class="hlt">flux</span> variations exhibit a low-amplitude, long-term modulation of a dominant annual <span class="hlt">cycle</span>. Predictor-hindcastor analyses indicate that skilled forecasts of nitrate concentration and nitrate <span class="hlt">flux</span> fields are feasible. Water discharge was the most reliably hindcast (on seasonal to interannual time scales) due to the fundamental strength of the annual hydrologic <span class="hlt">cycle</span>. However, the forecasting effort for this variable was less successful than the hindcasting effort, mostly due to a phase shift in the annual <span class="hlt">cycle</span> during our relatively short test period (18 mo). Nitrate concentration was more skillfully predicted (seasonal to interannual time scales) due to the relative dominance of the decadal-scale portion of the signal. Nitrate <span class="hlt">flux</span> was also skillfully forecast even though historical analyses seemed to indicate that it should be more difficult to predict than either water discharge or nitrate concentration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017SuScT..30l5015C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017SuScT..30l5015C"><span>A finite element calculation of <span class="hlt">flux</span> pumping</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Campbell, A. M.</p> <p>2017-12-01</p> <p>A <span class="hlt">flux</span> pump is not only a fascinating example of the power of Faraday’s concept of <span class="hlt">flux</span> lines, but also an attractive way of powering superconducting magnets without large electronic power supplies. However it is not possible to do this in HTS by driving a part of the superconductor normal, it must be done by exceeding the local critical density. The picture of a magnet pulling <span class="hlt">flux</span> lines through the material is attractive, but as there is no direct contact between <span class="hlt">flux</span> lines in the magnet and vortices, unless the gap between them is comparable to the coherence length, the process must be explicable in terms of classical electromagnetism and a nonlinear V-I characteristic. In this paper a simple 2D model of a <span class="hlt">flux</span> pump is used to determine the pumping behaviour from first principles and the geometry. It is analysed with finite element software using the A formulation and FlexPDE. A thin magnet is passed across one or more superconductors connected to a load, which is a large rectangular loop. This means that the self and mutual inductances can be calculated explicitly. A wide strip, a narrow strip and two conductors are considered. Also an analytic circuit model is analysed. In all cases the critical state model is used, so the <span class="hlt">flux</span> flow resistivity and dynamic resistivity are not directly involved, although an effective resistivity appears when J c is exceeded. In most of the cases considered here is a large gap between the theory and the experiments. In particular the maximum <span class="hlt">flux</span> transferred to the load area is always less than the <span class="hlt">flux</span> of the magnet. Also once the threshold needed for pumping is exceeded the <span class="hlt">flux</span> in the load saturates within a few <span class="hlt">cycles</span>. However the analytic circuit model allows a simple modification to allow for the large reduction in I c when the magnet is over a conductor. This not only changes the direction of the pumped <span class="hlt">flux</span> but leads to much more effective pumping.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B23E0644C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B23E0644C"><span>Low methane <span class="hlt">flux</span> from a constructed boreal wetland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Clark, M. G.; Humphreys, E.; Carey, S. K.</p> <p>2016-12-01</p> <p>The Sandhill Fen Watershed project in northern Alberta, Canada, is a pilot study in reconstructing a mixed upland and lowland boreal plain ecosystem. The physical construction of the 50 ha area was completed in 2012 and revegetation programs, through planting and seeding, began that same year and continued into 2013. Since then, the vegetation has developed a substantial cover over the reclaimed soil and peat substrates used to cap the engineered topography constructed from mine tailings. To monitor the dynamics of carbon <span class="hlt">cycling</span> processes in this novel ecosystem, near weekly gas chamber measurements of methane <span class="hlt">fluxes</span> were carried out over 3 growing seasons. Soil moisture, temperature and ion <span class="hlt">flux</span> measurements, using Plant Root Simulator probes, were also collected alongside the gas <span class="hlt">flux</span> plots. In the 3rd season, a transect was established in the lowlands along a moisture gradient to collect continuous reduction-oxidation potential measurements along with these other variables. Overall, methane effluxes remained low relative to what is expected for rewetted organic substrates. However, there is a trend over time towards increasing methane gas emissions that coincides with increasing <span class="hlt">fluxes</span> of reduced metal ions and decreasing <span class="hlt">fluxes</span> of sulphate in the fully saturated substrates. The suppressed levels of methane <span class="hlt">fluxes</span> are possibly due to naturally occurring high levels of sulphate in the donor materials used to cap the ecosystem construction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003JGRD..108.8224W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003JGRD..108.8224W"><span>Soil surface CO2 <span class="hlt">flux</span> in a boreal black spruce fire chronosequence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Chuankuan; Bond-Lamberty, Ben; Gower, Stith T.</p> <p>2003-02-01</p> <p>Understanding the effects of wildfire on the carbon (C) <span class="hlt">cycle</span> of boreal forests is essential to quantifying the role of boreal forests in the global carbon <span class="hlt">cycle</span>. Soil surface CO2 <span class="hlt">flux</span> (Rs), the second largest C <span class="hlt">flux</span> in boreal forests, is directly and indirectly affected by fire and is hypothesized to change during forest succession following fire. The overall objective of this study was to measure and model Rs for a black spruce (Picea mariana [Mill.] BSP) postfire chronosequence in northern Manitoba, Canada. The experiment design was a nested factorial that included two soil drainage classes (well and poorly drained) × seven postfire aged stands. Specific objectives were (1) to quantify the relationship between Rs and soil temperature for different aged boreal black spruce forests in well-drained and poorly drained soil conditions, (2) to examine Rs dynamics along postfire successional stands, and (3) to estimate annual soil surface CO2 <span class="hlt">flux</span> for these ecosystems. Soil surface CO2 <span class="hlt">flux</span> was significantly affected by soil drainage class (p = 0.014) and stand age (p = 0.006). Soil surface CO2 <span class="hlt">flux</span> was positively correlated to soil temperature (R2 = 0.78, p < 0.001), but different models were required for each drainage class × aged stand combination. Soil surface CO2 <span class="hlt">flux</span> was significantly greater at the well-drained than the poorly drained stands (p = 0.007) during growing season. Annual soil surface CO2 <span class="hlt">flux</span> for the 1998, 1995, 1989, 1981, 1964, 1930, and 1870 burned stands averaged 226, 412, 357, 413, 350, 274, and 244 g C m-2 yr-1 in the well-drained stands and 146, 380, 300, 303, 256, 233, and 264 g C m-2 yr-1 in the poorly drained stands. Soil surface CO2 <span class="hlt">flux</span> during the winter (from 1 November to 30 April) comprised from 5 to 19% of the total annual Rs. We speculate that the smaller soil surface CO2 <span class="hlt">flux</span> in the recently burned than the older stands is mainly caused by decreased root respiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002JGRD..107.8224W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002JGRD..107.8224W"><span>Soil surface CO2 <span class="hlt">flux</span> in a boreal black spruce fire chronosequence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Chuankuan; Bond-Lamberty, Ben; Gower, Stith T.</p> <p>2002-02-01</p> <p>Understanding the effects of wildfire on the carbon (C) <span class="hlt">cycle</span> of boreal forests is essential to quantifying the role of boreal forests in the global carbon <span class="hlt">cycle</span>. Soil surface CO2 <span class="hlt">flux</span> (Rs), the second largest C <span class="hlt">flux</span> in boreal forests, is directly and indirectly affected by fire and is hypothesized to change during forest succession following fire. The overall objective of this study was to measure and model Rs for a black spruce (Picea mariana [Mill.] BSP) postfire chronosequence in northern Manitoba, Canada. The experiment design was a nested factorial that included two soil drainage classes (well and poorly drained) × seven postfire aged stands. Specific objectives were (1) to quantify the relationship between Rs and soil temperature for different aged boreal black spruce forests in well-drained and poorly drained soil conditions, (2) to examine Rs dynamics along postfire successional stands, and (3) to estimate annual soil surface CO2 <span class="hlt">flux</span> for these ecosystems. Soil surface CO2 <span class="hlt">flux</span> was significantly affected by soil drainage class (p = 0.014) and stand age (p = 0.006). Soil surface CO2 <span class="hlt">flux</span> was positively correlated to soil temperature (R2 = 0.78, p < 0.001), but different models were required for each drainage class × aged stand combination. Soil surface CO2 <span class="hlt">flux</span> was significantly greater at the well-drained than the poorly drained stands (p = 0.007) during growing season. Annual soil surface CO2 <span class="hlt">flux</span> for the 1998, 1995, 1989, 1981, 1964, 1930, and 1870 burned stands averaged 226, 412, 357, 413, 350, 274, and 244 g C m-2 yr-1 in the well-drained stands and 146, 380, 300, 303, 256, 233, and 264 g C m-2 yr-1 in the poorly drained stands. Soil surface CO2 <span class="hlt">flux</span> during the winter (from 1 November to 30 April) comprised from 5 to 19% of the total annual Rs. We speculate that the smaller soil surface CO2 <span class="hlt">flux</span> in the recently burned than the older stands is mainly caused by decreased root respiration.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28944134','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28944134"><span>CO2 <span class="hlt">flux</span> from Javanese mud volcanism.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Queißer, M; Burton, M R; Arzilli, F; Chiarugi, A; Marliyani, G I; Anggara, F; Harijoko, A</p> <p>2017-06-01</p> <p>Studying the quantity and origin of CO 2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon <span class="hlt">cycle</span>. We measured CO 2 <span class="hlt">fluxes</span> of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO 2 with a volume fraction of at least 16 vol %. A lower limit CO 2 <span class="hlt">flux</span> of 1.4 kg s -1 (117 t d -1 ) was determined, in line with the CO 2 <span class="hlt">flux</span> from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO 2 <span class="hlt">flux</span> of 3 kt d -1 , comparable with the expected back-arc efflux of magmatic CO 2 . After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO 2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO 2 , with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO 2 <span class="hlt">fluxes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRB..122.4191Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRB..122.4191Q"><span>CO2 <span class="hlt">flux</span> from Javanese mud volcanism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Queißer, M.; Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.</p> <p>2017-06-01</p> <p>Studying the quantity and origin of CO2 emitted by back-arc mud volcanoes is critical to correctly model fluid-dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon <span class="hlt">cycle</span>. We measured CO2 <span class="hlt">fluxes</span> of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 <span class="hlt">flux</span> of 1.4 kg s-1 (117 t d-1) was determined, in line with the CO2 <span class="hlt">flux</span> from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 <span class="hlt">flux</span> of 3 kt d-1, comparable with the expected back-arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man-portable active remote sensing instruments for probing natural gas releases, enabling bottom-up quantification of CO2 <span class="hlt">fluxes</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B21F0487H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B21F0487H"><span>The Role of Surface Water Flow in Gas <span class="hlt">Fluxes</span> from a Subtropical Rice Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huynh, K. T.; Suvocarev, K.; Reavis, C.; Runkle, B.; Variano, E. A.</p> <p>2016-12-01</p> <p>Wetlands are the single largest source of methane emissions, but the underlying processes behind this <span class="hlt">flux</span> are not yet fully understood. Typically, methane <span class="hlt">fluxes</span> from wetlands have been attributed to ebullition (bubbling) and to transport through vegetation. However, a third major pathway-hydrodynamic transport-has been seen in a temperate wetland in the Sacramento-San Joaquin Delta. We wish to explore whether this additional pathway is also important to a subtropical rice paddy site where the diel thermal <span class="hlt">cycle</span> is less pronounced than in the temperate site. Measurements in the surface water of a rice field were collected over two weeks. Specific measurements collected included dissolved and atmospheric methane concentration, surface water velocity, and air and water temperature. These were used to augment a long-term dataset of micrometeorology and gas <span class="hlt">fluxes</span>. Together, these data demonstrate the role that surface water motions play in the <span class="hlt">fluxes</span> between soil and atmosphere. Data are analyzed to reveal the fraction of total methane <span class="hlt">flux</span> that is governed by advective/diffusive transport through surface water, and daily <span class="hlt">cycles</span> in this behavior. Results will be used to advance predictions of atmospheric methane gas concentrations and could be foundational for developing methane management solutions. Closing this gap in knowledge is key to improving calculations of current global greenhouse gas emissions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010EGUGA..1213141G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010EGUGA..1213141G"><span>Analysis of Surface <span class="hlt">Fluxes</span> at Eureka Climate Observatory in Arctic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grachev, Andrey; Albee, Robert; Fairall, Christopher; Hare, Jeffrey; Persson, Ola; Uttal, Taneil</p> <p>2010-05-01</p> <p>The Arctic region is experiencing unprecedented changes associated with increasing average temperatures (faster than the pace of the globally-averaged increase) and significant decreases in both the areal extent and thickness of the Arctic pack ice. These changes are early warning signs of shifts in the global climate system that justifies increased scientific focus on this region. The increase in atmospheric carbon dioxide has raised concerns worldwide about future climate change. Recent studies suggest that huge stores of carbon dioxide (and other climate relevant compounds) locked up in Arctic soils could be unexpectedly released due to global warming. Observational evidence suggests that atmospheric energy <span class="hlt">fluxes</span> are a major contributor to the decrease of the Arctic pack ice, seasonal land snow cover and the warming of the surrounding land areas and permafrost layers. To better understand the atmosphere-surface exchange mechanisms, improve models, and to diagnose climate variability in the Arctic, accurate measurements are required of all components of the net surface energy budget and the carbon dioxide <span class="hlt">cycle</span> over representative areas and over multiple years. In this study we analyze variability of turbulent <span class="hlt">fluxes</span> including water vapor and carbon dioxide transfer based on long-term measurements made at Eureka observatory (80.0 N, 85.9 W) located near the coast of the Arctic Ocean (Canadian territory of Nunavut). Turbulent <span class="hlt">fluxes</span> and mean meteorological data are continuously measured and reported hourly at various levels on a 10-m <span class="hlt">flux</span> tower. Sonic anemometers are located at 3 and 8 m heights while high-speed Licor 7500 infrared gas analyzer (water moisture and carbon dioxide measurements) at 7.5 m height. According to our data, that the sensible heat <span class="hlt">flux</span>, carbon dioxide and water vapor <span class="hlt">fluxes</span> exhibited clear diurnal <span class="hlt">cycles</span> in Arctic summer. This behavior is similar to the diurnal variation of the <span class="hlt">fluxes</span> in mid-latitudes during the plants growing season, with</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.B43E2180T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.B43E2180T"><span>CO2 and CH4 <span class="hlt">fluxes</span> in a Spartina salt marsh and brackish Phragmites marsh in Massachusetts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, J.; Wang, F.; Kroeger, K. D.; Gonneea, M. E.</p> <p>2017-12-01</p> <p>Coastal salt marshes play an important role in global and regional carbon <span class="hlt">cycling</span>. Tidally restricted marshes reduce salinity and provide a habitat suitable for Phragmites invasion. We measured greenhouse gas (GHG) emissions (CO2 and CH4) continuously with the eddy covariance method and biweekly with the static chamber method in a Spartina salt marsh and a Phragmites marsh on Cape Cod, Massachusetts, USA. We did not find significant difference in CO2 <span class="hlt">fluxes</span> between the two sites, but the CH4 <span class="hlt">fluxes</span> were much higher in the Phragmites site than the Spartina marsh. Temporally, tidal <span class="hlt">cycles</span> influence the CO2 and CH4 <span class="hlt">fluxes</span> in both sites. We found that the salt marsh was a significant carbon sink when CO2 and CH4 <span class="hlt">fluxes</span> were combined. Restoring tidally restricted marshes will significantly reduce CH4 emissions and provide a strong ecosystem carbon service.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JAMES..10..617B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JAMES..10..617B"><span>A Comparison of the Diel <span class="hlt">Cycle</span> of Modeled and Measured Latent Heat <span class="hlt">Flux</span> During the Warm Season in a Colorado Subalpine Forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burns, Sean P.; Swenson, Sean C.; Wieder, William R.; Lawrence, David M.; Bonan, Gordon B.; Knowles, John F.; Blanken, Peter D.</p> <p>2018-03-01</p> <p>Precipitation changes the physiological characteristics of an ecosystem. Because land-surface models are often used to project changes in the hydrological <span class="hlt">cycle</span>, modeling the effect of precipitation on the latent heat <span class="hlt">flux</span> λE is an important aspect of land-surface models. Here we contrast conditionally sampled diel composites of the eddy-covariance <span class="hlt">fluxes</span> from the Niwot Ridge Subalpine Forest Ameri<span class="hlt">Flux</span> tower with the Community Land Model (CLM, version 4.5). With respect to measured λE during the warm season: for the day following above-average precipitation, λE was enhanced at midday by ≈40 W m-2 (relative to dry conditions), and nocturnal λE increased from ≈10 W m-2 in dry conditions to over 20 W m-2 in wet conditions. With default settings, CLM4.5 did not successfully model these changes. By increasing the amount of time that rainwater was retained by the canopy/needles, CLM was able to match the observed midday increase in λE on a dry day following a wet day. Stable nighttime conditions were problematic for CLM4.5. Nocturnal CLM λE had only a small (≈3 W m-2) increase during wet conditions, CLM nocturnal friction velocity u∗ was smaller than observed u∗, and CLM canopy air temperature was 2°C less than those measured at the site. Using observed u∗ as input to CLM increased λE; however, this caused CLM λE to be increased during both wet and dry periods. We suggest that sloped topography and the ever-present drainage flow enhanced nocturnal u∗ and λE. Such phenomena would not be properly captured by topographically blind land-surface models, such as CLM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.B51D1000C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.B51D1000C"><span>FLUXNET: A Global Network of Eddy-Covariance <span class="hlt">Flux</span> Towers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cook, R. B.; Holladay, S. K.; Margle, S. M.; Olsen, L. M.; Gu, L.; Heinsch, F.; Baldocchi, D.</p> <p>2003-12-01</p> <p>The FLUXNET global network was established to aid in understanding the mechanisms controlling the exchanges of carbon dioxide, water vapor, and energy across a variety of terrestrial ecosystems. <span class="hlt">Flux</span> tower data are also being used to validate ecosystem model outputs and to provide information for validating remote sensing based products, including surface temperature, reflectance, albedo, vegetation indices, leaf area index, photosynthetically active radiation, and photosynthesis derived from MODIS sensors on the Terra and Aqua satellites. The global FLUXNET database provides consistent and complete <span class="hlt">flux</span> data to support global carbon <span class="hlt">cycle</span> science. Currently FLUXNET consists of over 210 sites, with most <span class="hlt">flux</span> towers operating continuously for 4 years or longer. Gap-filled data are available for 53 sites. The FLUXNET database contains carbon, water vapor, sensible heat, momentum, and radiation <span class="hlt">flux</span> measurements with associated ancillary and value-added data products. Towers are located in temperate conifer and broadleaf forests, tropical and boreal forests, crops, grasslands, chaparral, wetlands, and tundra on five continents. Selected MODIS Land products in the immediate vicinity of the <span class="hlt">flux</span> tower are subsetted and posted on the FLUXNET Web site for 169 <span class="hlt">flux</span>-towers. The MODIS subsets are prepared in ASCII format for 8-day periods for an area 7 x 7 km around the tower.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.A41A0026S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.A41A0026S"><span>Advances in the Surface Renewal <span class="hlt">Flux</span> Measurement Method</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shapland, T. M.; McElrone, A.; Paw U, K. T.; Snyder, R. L.</p> <p>2011-12-01</p> <p>The measurement of ecosystem-scale energy and mass <span class="hlt">fluxes</span> between the planetary surface and the atmosphere is crucial for understanding geophysical processes. Surface renewal is a <span class="hlt">flux</span> measurement technique based on analyzing the turbulent coherent structures that interact with the surface. It is a less expensive technique because it does not require fast-response velocity measurements, but only a fast-response scalar measurement. It is therefore also a useful tool for the study of the global <span class="hlt">cycling</span> of trace gases. Currently, surface renewal requires calibration against another <span class="hlt">flux</span> measurement technique, such as eddy covariance, to account for the linear bias of its measurements. We present two advances in the surface renewal theory and methodology that bring the technique closer to becoming a fully independent <span class="hlt">flux</span> measurement method. The first advance develops the theory of turbulent coherent structure transport associated with the different scales of coherent structures. A novel method was developed for identifying the scalar change rate within structures at different scales. Our results suggest that for canopies less than one meter in height, the second smallest coherent structure scale dominates the energy and mass <span class="hlt">flux</span> process. Using the method for resolving the scalar exchange rate of the second smallest coherent structure scale, calibration is unnecessary for surface renewal measurements over short canopies. This study forms the foundation for analysis over more complex surfaces. The second advance is a sensor frequency response correction for measuring the sensible heat <span class="hlt">flux</span> via surface renewal. Inexpensive fine-wire thermocouples are frequently used to record high frequency temperature data in the surface renewal technique. The sensible heat <span class="hlt">flux</span> is used in conjunction with net radiation and ground heat <span class="hlt">flux</span> measurements to determine the latent heat <span class="hlt">flux</span> as the energy balance residual. The robust thermocouples commonly used in field experiments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=%22water+cycle%22+AND+Climate&id=ED416069','ERIC'); return false;" href="https://eric.ed.gov/?q=%22water+cycle%22+AND+Climate&id=ED416069"><span>Biomes and Natural <span class="hlt">Cycles</span>. [CD-ROM].</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>1996</p> <p></p> <p>This interactive multimedia software illustrates and explains life on planet Earth through colorful and dynamic representations. Clear explanations and animation elucidate a variety of subjects such as the organization of the ecosphere, the <span class="hlt">flux</span> of energy, water <span class="hlt">cycles</span>, climates, and characteristics of regions across the globe. Five animated films…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20060038010&hterms=water+cycles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwater%2Bcycles','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20060038010&hterms=water+cycles&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dwater%2Bcycles"><span>GEWEX: The Global Energy and Water <span class="hlt">Cycle</span> Experiment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chahine, M.; Vane, D.</p> <p>1994-01-01</p> <p>GEWEX is one of the world's largest global change research programs. Its purpose is to observe and understand the hydrological <span class="hlt">cycle</span> and energy <span class="hlt">fluxes</span> in the atmosphere, at land surfaces and in the upper oceans.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1259277','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1259277"><span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Schwender, Jorg; Konig, Christina; Klapperstuck, Matthias</p> <p></p> <p>An attempt has been made to define the extent to which metabolic <span class="hlt">flux</span> in central plant metabolism is reflected by changes in the transcriptome and metabolome, based on an analysis of in vitro cultured immature embryos of two oilseed rape (Brassica napus) accessions which contrast for seed lipid accumulation. Metabolic <span class="hlt">flux</span> analysis (MFA) was used to constrain a <span class="hlt">flux</span> balance metabolic model which included 671 biochemical and transport reactions within the central metabolism. This highly confident <span class="hlt">flux</span> information was eventually used for comparative analysis of <span class="hlt">flux</span> vs. transcript (metabolite). Metabolite profiling succeeded in identifying 79 intermediates within the central metabolism,more » some of which differed quantitatively between the two accessions and displayed a significant shift corresponding to <span class="hlt">flux</span>. An RNA-Seq based transcriptome analysis revealed a large number of genes which were differentially transcribed in the two accessions, including some enzymes/proteins active in major metabolic pathways. With a few exceptions, differential activity in the major pathways (glycolysis, <span class="hlt">TCA</span> <span class="hlt">cycle</span>, amino acid, and fatty acid synthesis) was not reflected in contrasting abundances of the relevant transcripts. The conclusion was that transcript abundance on its own cannot be used to infer metabolic activity/<span class="hlt">fluxes</span> in central plant metabolism. Lastly, this limitation needs to be borne in mind in evaluating transcriptome data and designing metabolic engineering experiments.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.5307C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.5307C"><span>Annual, semi-annual and ter-annual variations of gravity wave momentum <span class="hlt">flux</span> in 13 years of SABER data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, Dan; Preusse, Peter; Ern, Manfred; Strube, Cornelia</p> <p>2017-04-01</p> <p>In this study, the variations at different time scales such as the annual <span class="hlt">cycle</span>, the semiannual oscillation (SAO), the ter-annual <span class="hlt">cycle</span> (about four monthly) and the quasi-biennial oscillation (QBO) in zonal mean GW amplitudes and GW momentum <span class="hlt">flux</span> (GWMF) have been investigated using satellite observations from 2002-2014 and combining ECMWF high resolution data with the GORGRAT model. The global distribution (patterns) of spectral amplitudes of GW momentum <span class="hlt">flux</span> in stratosphere and mesosphere (from 30 km to 90 km) show that the annual <span class="hlt">cycle</span> is the most predominant variation, and then are SAO, ter-annual <span class="hlt">cycle</span> and QBO. For annual components, two relatively isolated amplitude maxima appear in each hemisphere: a subtropical maximum is associated with convective sources in summer, a mid and high latitude maximum is associated with the polar vortex in winter. In the subtropics, GWs propagate upward obliquely to the higher latitudes. The winter maximum in the southern hemisphere has larger momentum <span class="hlt">flux</span> than that one in the northern hemisphere. While on the SH the phase (i.e. time corresponding to the maximum GWMF) continuously descends with the maximum in July in the upper mesosphere and in September in the lower stratosphere, on the northern hemisphere, the phase has no visible altitude dependence with a maximum in December. For semiannual variations, in the MLT (70-80 km) region, there is an obvious enhancement of spectral amplitude at equatorial latitudes which relate to the dissipation of convectively forced GWs. The SAO in absolute momentum <span class="hlt">flux</span> and the annual <span class="hlt">cycle</span> in zonal momentum <span class="hlt">flux</span> indicated that the variations at mid-latitudes (about from 30°-40°) are not a SAO signals but rather an annual <span class="hlt">cycle</span> when the direction of GWMF is considered. The ter-annual <span class="hlt">cycle</span> may be related to the duration of active convection in subtropical latitudes (from June to Sep. in north hemisphere) Indications for QBO are found latitude extension to mid-latitudes in stratosphere of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014BGD....1117187J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014BGD....1117187J"><span>Lunar periodicity in the shell <span class="hlt">flux</span> of some planktonic foraminifera in the Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonkers, L.; Reynolds, C. E.; Richey, J.; Hall, I. R.</p> <p>2014-12-01</p> <p>Synchronised reproduction offers clear benefits to planktonic foraminifera - an important group of marine calcifiers - as it increases the chances of successful gamete fusion. Such synchrony requires tuning to an internal or external clock. Evidence exists for lunar reproductive <span class="hlt">cycles</span> in some species, but its recognition in shell <span class="hlt">flux</span> time series has proven difficult, raising questions about reproductive strategies. Using spectral analysis of a 6 year time series (mostly at weekly resolution) from the northern Gulf of Mexico we show that the shell <span class="hlt">flux</span> of Globorotalia menardii, Globigerinella siphonifera, Orbulina universa, Globigerinoides sacculifer and in Globigerinoides ruber (both pink and white varieties) is characterised by lunar periodicity. The <span class="hlt">fluxes</span> of Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globigerinella calida, Globorotalia crassaformis and Globigerinita glutinata do not show significant spectral power at the lunar frequency. If present, lunar periodicity is superimposed on longer term/seasonal changes in the shell <span class="hlt">fluxes</span>, but accounts for a significant part of the variance in the <span class="hlt">fluxes</span>. The amplitude of the lunar <span class="hlt">cycle</span> increases roughly proportional with the magnitude of the <span class="hlt">flux</span>, demonstrating that most of the population is indeed affected by lunar-phased synchronisation. Phasing of peak <span class="hlt">fluxes</span> appears species-specific, with G. menardii, O. universa and G. sacculifer showing most peaks around the full moon and G. ruber one week later. Contrastingly, peaks G. siphonifera occur dominantly around new moon. Very limited literature exists on lunar phasing of foraminiferal export <span class="hlt">fluxes</span>, but spatial differences in its presence may exist, corroborating the exogenous nature of lunar synchrony in planktonic foraminifera.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011BGD.....8.7475K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011BGD.....8.7475K"><span>The imprint of surface <span class="hlt">fluxes</span> and transport on variations in total column carbon dioxide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Keppel-Aleks, G.; Wennberg, P. O.; Washenfelder, R. A.; Wunch, D.; Schneider, T.; Toon, G. C.; Andres, R. J.; Blavier, J.-F.; Connor, B.; Davis, K. J.; Desai, A. R.; Messerschmidt, J.; Notholt, J.; Roehl, C. M.; Sherlock, V.; Stephens, B. B.; Vay, S. A.; Wofsy, S. C.</p> <p>2011-07-01</p> <p>New observations of the vertically integrated CO2 mixing ratio, ⟨CO2⟩, from ground-based remote sensing show that variations in ⟨CO2⟩ are primarily determined by large-scale <span class="hlt">flux</span> patterns. They therefore provide fundamentally different information than observations made within the boundary layer, which reflect the combined influence of large scale and local <span class="hlt">fluxes</span>. Observations of both ⟨CO2⟩ and CO2 concentrations in the free troposphere show that large-scale spatial gradients induce synoptic-scale temporal variations in ⟨CO2⟩ in the Northern Hemisphere midlatitudes through horizontal advection. Rather than obscure the signature of surface <span class="hlt">fluxes</span> on atmospheric CO2, these synoptic-scale variations provide useful information that can be used to reveal the meridional <span class="hlt">flux</span> distribution. We estimate the meridional gradient in ⟨CO2⟩ from covariations in ⟨CO2⟩ and potential temperature, θ, a dynamical tracer, on synoptic timescales to evaluate surface <span class="hlt">flux</span> estimates commonly used in carbon <span class="hlt">cycle</span> models. We find that Carnegie Ames Stanford Approach (CASA) biospheric <span class="hlt">fluxes</span> underestimate both the ⟨CO2⟩ seasonal <span class="hlt">cycle</span> amplitude throughout the Northern Hemisphere midlatitudes as well as the meridional gradient during the growing season. Simulations using CASA net ecosystem exchange (NEE) with increased and phase-shifted boreal <span class="hlt">fluxes</span> better reflect the observations. Our simulations suggest that boreal growing season NEE (between 45-65° N) is underestimated by ~40 % in CASA. We describe the implications for this large seasonal exchange on inference of the net Northern Hemisphere terrestrial carbon sink.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GBioC..30.1509B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GBioC..30.1509B"><span>The role of metabolism in modulating CO2 <span class="hlt">fluxes</span> in boreal lakes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bogard, Matthew J.; del Giorgio, Paul A.</p> <p>2016-10-01</p> <p>Lake CO2 emissions are increasingly recognized as an important component of the global CO2 <span class="hlt">cycle</span>, yet the origin of these emissions is not clear, as specific contributions from metabolism and in-lake <span class="hlt">cycling</span>, versus external inputs, are not well defined. To assess the coupling of lake metabolism with CO2 concentrations and <span class="hlt">fluxes</span>, we estimated steady state ratios of gross primary production to respiration (GPP:R) and rates of net ecosystem production (NEP = GPP-R) from surface water O2 dynamics (concentration and stable isotopes) in 187 boreal lakes spanning long environmental gradients. Our findings suggest that internal metabolism plays a dominant role in regulating CO2 <span class="hlt">fluxes</span> in most lakes, but this pattern only emerges when examined at a resolution that accounts for the vastly differing relationships between lake metabolism and CO2 <span class="hlt">fluxes</span>. <span class="hlt">Fluxes</span> of CO2 exceeded those from NEP in over half the lakes, but unexpectedly, these effects were most common and typically largest in a subset ( 30% of total) of net autotrophic lakes that nevertheless emitted CO2. Equally surprising, we found no environmental characteristics that distinguished this category from the more common net heterotrophic, CO2 outgassing lakes. Excess CO2 <span class="hlt">fluxes</span> relative to NEP were best predicted by catchment structure and hydrologic properties, and we infer from a combination of methods that both catchment inputs and internal anaerobic processes may have contributed this excess CO2. Together, our findings show that the link between lake metabolism and CO2 <span class="hlt">fluxes</span> is often strong but can vary widely across the boreal biome, having important implications for catchment-wide C budgets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000057261&hterms=ghosts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dghosts','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000057261&hterms=ghosts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dghosts"><span>Ames Optimized <span class="hlt">TCA</span> Configuration</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cliff, Susan E.; Reuther, James J.; Hicks, Raymond M.</p> <p>1999-01-01</p> <p>Configuration design at Ames was carried out with the SYN87-SB (single block) Euler code using a 193 x 49 x 65 C-H grid. The Euler solver is coupled to the constrained (NPSOL) and the unconstrained (QNMDIF) optimization packages. Since the single block grid is able to model only wing-body configurations, the nacelle/diverter effects were included in the optimization process by SYN87's option to superimpose the nacelle/diverter interference pressures on the wing. These interference pressures were calculated using the AIRPLANE code. AIRPLANE is an Euler solver that uses a unstructured tetrahedral mesh and is capable of computations about arbitrary complete configurations. In addition, the buoyancy effects of the nacelle/diverters were also included in the design process by imposing the pressure field obtained during the design process onto the triangulated surfaces of the nacelle/diverter mesh generated by AIRPLANE. The interference pressures and nacelle buoyancy effects are added to the final forces after each flow field calculation. Full details of the (recently enhanced) ghost nacelle capability are given in a related talk. The pseudo nacelle corrections were greatly improved during this design <span class="hlt">cycle</span>. During the Ref H and <span class="hlt">Cycle</span> 1 design activities, the nacelles were only translated and pitched. In the <span class="hlt">cycle</span> 2 design effort the nacelles can translate vertically, and pitch to accommodate the changes in the lower surface geometry. The diverter heights (between their leading and trailing edges) were modified during design as the shape of the lower wing changed, with the drag of the diverter changing accordingly. Both adjoint and finite difference gradients were used during optimization. The adjoint-based gradients were found to give good direction in the design space for configurations near the starting point, but as the design approached a minimum, the finite difference gradients were found to be more accurate. Use of finite difference gradients was limited by the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SoPh..289.2141I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SoPh..289.2141I"><span>Three-Dimensional Evolution of <span class="hlt">Flux</span>-Rope CMEs and Its Relation to the Local Orientation of the Heliospheric Current Sheet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Isavnin, A.; Vourlidas, A.; Kilpua, E. K. J.</p> <p>2014-06-01</p> <p><span class="hlt">Flux</span> ropes ejected from the Sun may change their geometrical orientation during their evolution, which directly affects their geoeffectiveness. Therefore, it is crucial to understand how solar <span class="hlt">flux</span> ropes evolve in the heliosphere to improve our space-weather forecasting tools. We present a follow-up study of the concepts described by Isavnin, Vourlidas, and Kilpua ( Solar Phys. 284, 203, 2013). We analyze 14 coronal mass ejections (CMEs), with clear <span class="hlt">flux</span>-rope signatures, observed during the decay of Solar <span class="hlt">Cycle</span> 23 and rise of Solar <span class="hlt">Cycle</span> 24. First, we estimate initial orientations of the <span class="hlt">flux</span> ropes at the origin using extreme-ultraviolet observations of post-eruption arcades and/or eruptive prominences. Then we reconstruct multi-viewpoint coronagraph observations of the CMEs from ≈ 2 to 30 R⊙ with a three-dimensional geometric representation of a <span class="hlt">flux</span> rope to determine their geometrical parameters. Finally, we propagate the <span class="hlt">flux</span> ropes from ≈ 30 R⊙ to 1 AU through MHD-simulated background solar wind while using in-situ measurements at 1 AU of the associated magnetic cloud as a constraint for the propagation technique. This methodology allows us to estimate the <span class="hlt">flux</span>-rope orientation all the way from the Sun to 1 AU. We find that while the <span class="hlt">flux</span>-ropes' deflection occurs predominantly below 30 R⊙, a significant amount of deflection and rotation happens between 30 R⊙ and 1 AU. We compare the <span class="hlt">flux</span>-rope orientation to the local orientation of the heliospheric current sheet (HCS). We find that slow <span class="hlt">flux</span> ropes tend to align with the streams of slow solar wind in the inner heliosphere. During the solar-<span class="hlt">cycle</span> minimum the slow solar-wind channel as well as the HCS usually occupy the area in the vicinity of the solar equatorial plane, which in the past led researchers to the hypothesis that <span class="hlt">flux</span> ropes align with the HCS. Our results show that exceptions from this rule are explained by interaction with the Parker-spiraled background magnetic field, which dominates</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017ApJ...850...45R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017ApJ...850...45R"><span>Global Solar Magnetic Field Organization in the Outer Corona: Influence on the Solar Wind Speed and Mass <span class="hlt">Flux</span> Over the <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Réville, Victor; Brun, Allan Sacha</p> <p>2017-11-01</p> <p>The dynamics of the solar wind depends intrinsically on the structure of the global solar magnetic field, which undergoes fundamental changes over the 11-year solar <span class="hlt">cycle</span>. For instance, the wind terminal velocity is thought to be anti-correlated with the expansion factor, a measure of how the magnetic field varies with height in the solar corona, usually computed at a fixed height (≈ 2.5 {R}⊙ , the source surface radius that approximates the distance at which all magnetic field lines become open). However, the magnetic field expansion affects the solar wind in a more detailed way, its influence on the solar wind properties remaining significant well beyond the source surface. We demonstrate this using 3D global magnetohydrodynamic (MHD) simulations of the solar corona, constrained by surface magnetograms over half a solar <span class="hlt">cycle</span> (1989-2001). A self-consistent expansion beyond the solar wind critical point (even up to 10 {R}⊙ ) makes our model comply with observed characteristics of the solar wind, namely, that the radial magnetic field intensity becomes latitude independent at some distance from the Sun, and that the mass <span class="hlt">flux</span> is mostly independent of the terminal wind speed. We also show that near activity minimum, the expansion in the higher corona has more influence on the wind speed than the expansion below 2.5 {R}⊙ .</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=267929','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=267929"><span>Energy <span class="hlt">fluxes</span> estimation in a juniper tree area of the Donana biological reserve through TSEB method and Landsat-5TM imagery</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Energy <span class="hlt">fluxes</span> computing (actual evapotranspiration, net radiation, sensible heat and soil heat <span class="hlt">flux</span>) are essential to improve the knowledge of the hydrological <span class="hlt">cycle</span>, especially in natural vegetation covers. In this paper we present the first results of the energy <span class="hlt">fluxes</span> modeling by means of the TSE...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B43J..02M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B43J..02M"><span>The Ability of Atmospheric Data to Reduce Disagreements in Wetland Methane <span class="hlt">Flux</span> Estimates over North America</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Miller, S. M.; Andrews, A. E.; Benmergui, J. S.; Commane, R.; Dlugokencky, E. J.; Janssens-Maenhout, G.; Melton, J. R.; Michalak, A. M.; Sweeney, C.; Worthy, D. E. J.</p> <p>2015-12-01</p> <p>Existing estimates of methane <span class="hlt">fluxes</span> from wetlands differ in both magnitude and distribution across North America. We discuss seven different bottom-up methane estimates in the context of atmospheric methane data collected across the US and Canada. In the first component of this study, we explore whether the observation network can even detect a methane pattern from wetlands. We find that the observation network can identify a methane pattern from Canadian wetlands but not reliably from US wetlands. Over Canada, the network can even identify spatial patterns at multi-provence scales. Over the US, by contrast, anthropogenic emissions and modeling errors obscure atmospheric patterns from wetland <span class="hlt">fluxes</span>. In the second component of the study, we then use these observations to reconcile disagreements in the magnitude, seasonal <span class="hlt">cycle</span>, and spatial distribution of existing estimates. Most existing estimates predict <span class="hlt">fluxes</span> that are too large with a seasonal <span class="hlt">cycle</span> that is too narrow. A model known as LPJ-Bern has a spatial distribution most consistent with atmospheric observations. By contrast, a spatially-constant model outperforms the distribution of most existing <span class="hlt">flux</span> estimates across Canada. The results presented here provide several pathways to reduce disagreements among existing wetland <span class="hlt">flux</span> estimates across North America.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19920009517','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19920009517"><span>Miniature high temperature plug-type heat <span class="hlt">flux</span> gauges</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liebert, Curt H.</p> <p>1992-01-01</p> <p>The objective is to describe continuing efforts to develop methods for measuring surface heat <span class="hlt">flux</span>, gauge active surface temperature, and heat transfer coefficient quantities. The methodology involves inventing a procedure for fabricating improved plug-type heat <span class="hlt">flux</span> gauges and also for formulating inverse heat conduction models and calculation procedures. These models and procedures are required for making indirect measurements of these quantities from direct temperature measurements at gauge interior locations. Measurements of these quantities were made in a turbine blade thermal <span class="hlt">cycling</span> tester (TBT) located at MSFC. The TBT partially simulates the turbopump turbine environment in the Space Shuttle Main Engine. After the TBT test, experiments were performed in an arc lamp to analyze gauge quality.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22277885-novel-latch-adiabatic-quantum-flux-parametron-logic','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22277885-novel-latch-adiabatic-quantum-flux-parametron-logic"><span>Novel latch for adiabatic quantum-<span class="hlt">flux</span>-parametron logic</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Takeuchi, Naoki, E-mail: takeuchi-naoki-kx@ynu.jp; Yamanashi, Yuki; Yoshikawa, Nobuyuki</p> <p>2014-03-14</p> <p>We herein propose the quantum-<span class="hlt">flux</span>-latch (QFL) as a novel latch for adiabatic quantum-<span class="hlt">flux</span>-parametron (AQFP) logic. A QFL is very compact and compatible with AQFP logic gates and can be read out in one clock <span class="hlt">cycle</span>. Simulation results revealed that the QFL operates at 5 GHz with wide parameter margins of more than ±22%. The calculated energy dissipation was only ∼0.1 aJ/bit, which yields a small energy delay product of 20 aJ·ps. We also designed shift registers using QFLs to demonstrate more complex circuits with QFLs. Finally, we experimentally demonstrated correct operations of the QFL and a 1-bit shift register (a D flip-flop)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B44B..03K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B44B..03K"><span>Landscape analysis of methane <span class="hlt">flux</span> across complex terrain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaiser, K. E.; McGlynn, B. L.; Dore, J. E.</p> <p>2014-12-01</p> <p>Greenhouse gas (GHG) <span class="hlt">fluxes</span> into and out of the soil are influenced by environmental conditions resulting in landscape-mediated patterns of spatial heterogeneity. The temporal variability of inputs (e.g. precipitation) and internal redistribution (e.g. groundwater flow) and dynamics (e.g. microbial communities) make predicating these <span class="hlt">fluxes</span> challenging. Complex terrain can provide a laboratory for improving understanding of the spatial patterns, temporal dynamics, and drivers of trace gas <span class="hlt">flux</span> rates, requisite to constraining current GHG budgets and future scenarios. Our research builds on previous carbon <span class="hlt">cycle</span> research at the USFS Tenderfoot Creek Experimental Forest, Little Belt Mountains, Montana that highlighted the relationships between landscape position and seasonal CO2 efflux, induced by the topographic redistribution of water. Spatial patterns and landscape scale mediation of CH4 <span class="hlt">fluxes</span> in seasonally aerobic soils have not yet been elucidated. We measured soil methane concentrations and <span class="hlt">fluxes</span> across a full range of landscape positions, leveraging topographic and seasonal gradients, to examine the relationships between environmental variables, hydrologic dynamics, and CH4 production and consumption. We determined that a threshold of ~30% VWC distinguished the direction of <span class="hlt">flux</span> at individual time points, with the riparian area and uplands having distinct source/sink characteristics respectively. Riparian locations were either strong sources or fluctuated between sink and source behavior, resulting in near neutral seasonal <span class="hlt">flux</span>. Upland sites however, exhibited significant relationships between sink strength and topographic/energy balance indices. Our results highlight spatial and temporal coherence to landscape scale heterogeneity of CH4 dynamics that can improve estimates of landscape scale CH4 balances and sensitivity to change.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JMS...180...59V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JMS...180...59V"><span>Spatiotemporal variation of vertical particle <span class="hlt">fluxes</span> and modelled chlorophyll a standing stocks in the Benguela Upwelling System</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vorrath, Maria-Elena; Lahajnar, Niko; Fischer, Gerhard; Libuku, Viktor Miti; Schmidt, Martin; Emeis, Kay-Christian</p> <p>2018-04-01</p> <p>Marine particle <span class="hlt">fluxes</span> from high productive coastal upwelling systems return upwelled CO2 and nutrients to the deep ocean and sediments and have a substantial impact on the global carbon <span class="hlt">cycle</span>. This study examines relations between production regimes on the shelf and over the continental margin of the Benguela Upwelling System (BUS) in the SE Atlantic Ocean. Data of composition and timing of vertical particle <span class="hlt">flux</span> come from sediment trap time series (deployed intermittently between 1988 and 2014) in the regions Walvis Ridge, Walvis Bay, Luederitz and Orange River. We compare their seasonal variability to modelled patterns of chlorophyll concentrations in a 3-D ecosystem model. Both modelled seasonal chlorophyll a standing stocks and sampled particle <span class="hlt">flux</span> patterns are highly correspondent with a bimodal seasonal <span class="hlt">cycle</span> offshore the BUS. The material in the particle <span class="hlt">flux</span> in offshore traps is dominantly carbonate (40-70%), and <span class="hlt">flux</span> peaks in offshore particle <span class="hlt">flux</span> originate from two independent events: in austral autumn thermocline shoaling and vertical mixing are decoupled from coastal upwelling, while <span class="hlt">fluxes</span> in spring coincide with the upwelling season, indicated by slightly elevated biogenic opal values at some locations. Coastal particle <span class="hlt">fluxes</span> are characterized by a trimodal pattern and are dominated by biogenic opal (22-35%) and organic matter (30-60%). The distinct seasonality in observed <span class="hlt">fluxes</span> on the shelf is caused by high variability in production, sinking behaviour, wind stress, and hydrodynamic processes. We speculate that global warming will increase ocean stratification and alter coastal upwelling, so that consequences for primary production and particle <span class="hlt">flux</span> in the BUS are inevitable.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3188519','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3188519"><span>Fumarate Reductase Activity Maintains an Energized Membrane in Anaerobic Mycobacterium tuberculosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Watanabe, Shinya; Zimmermann, Michael; Goodwin, Michael B.; Sauer, Uwe; Barry, Clifton E.; Boshoff, Helena I.</p> <p>2011-01-01</p> <p>Oxygen depletion of Mycobacterium tuberculosis engages the DosR regulon that coordinates an overall down-regulation of metabolism while up-regulating specific genes involved in respiration and central metabolism. We have developed a chemostat model of M. tuberculosis where growth rate was a function of dissolved oxygen concentration to analyze metabolic adaptation to hypoxia. A drop in dissolved oxygen concentration from 50 mmHg to 0.42 mmHg led to a 2.3 fold decrease in intracellular ATP levels with an almost 70-fold increase in the ratio of NADH/NAD+. This suggests that re-oxidation of this co-factor becomes limiting in the absence of a terminal electron acceptor. Upon oxygen limitation genes involved in the reverse <span class="hlt">TCA</span> <span class="hlt">cycle</span> were upregulated and this upregulation was associated with a significant accumulation of succinate in the extracellular milieu. We confirmed that this succinate was produced by a reversal of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> towards the non-oxidative direction with net CO2 incorporation by analysis of the isotopomers of secreted succinate after feeding stable isotope (13C) labeled precursors. This showed that the resulting succinate retained both carbons lost during oxidative operation of the <span class="hlt">TCA</span> <span class="hlt">cycle</span>. Metabolomic analyses of all glycolytic and <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates from 13C-glucose fed cells under aerobic and anaerobic conditions showed a clear reversal of isotope labeling patterns accompanying the switch from normoxic to anoxic conditions. M. tuberculosis encodes three potential succinate-producing enzymes including a canonical fumarate reductase which was highly upregulated under hypoxia. Knockout of frd, however, failed to reduce succinate accumulation and gene expression studies revealed a compensatory upregulation of two homologous enzymes. These major realignments of central metabolism are consistent with a model of oxygen-induced stasis in which an energized membrane is maintained by coupling the reductive branch of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> to succinate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1815271P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1815271P"><span>Plant phenology and composition controls of carbon <span class="hlt">fluxes</span> in a boreal peatland</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peichl, Matthias; Gažovič, Michal; Vermeij, Ilse; De Goede, Eefje; Sonnentag, Oliver; Limpens, Juul; Nilsson, Mats B.</p> <p>2016-04-01</p> <p>Vegetation drives the peatland carbon (C) <span class="hlt">cycle</span> via the processes of photosynthesis, plant respiration and decomposition as well as by providing substrate for methane (CH4) and dissolved organic carbon production. However, due to the lack of comprehensive vegetation data, variations in the peatland C <span class="hlt">fluxes</span> are commonly related to temperature and other more easily measured abiotic (i.e. weather and soil) variables. Due to the temporal co-linearity between plant development and abiotic variables, these relationships may describe the variations in C <span class="hlt">fluxes</span> reasonably well, however, without representing the true mechanistic processes driving the peatland C <span class="hlt">cycle</span>. As a consequence, current process-based models are poorly parameterized and unable to adequately predict the responses of the peatland C <span class="hlt">cycle</span> to climate change, extreme events and anthropogenic impacts. To fill this knowledge gap, we explored vegetation phenology and composition effects on the peatland C <span class="hlt">cycle</span> at the Degerö peatland located in northern Sweden. We used a greenness index derived from digital repeat photography to quantitatively describe plant canopy development with high temporal (i.e. daily) and spatial (plot to ecosystem) resolution. In addition, eddy covariance and static chamber measurements of carbon dioxide (CO2) and CH4 <span class="hlt">fluxes</span> over an array of vegetation manipulation plots were conducted over multiple years. Our results suggest that vascular plant phenology controls the onset and pattern of eddy covariance-derived gross primary production (GPP) during the spring period, while abiotic conditions modify GPP during the summer period when plant canopy cover is fully developed. Inter-annual variations in the spring onset and patterns of plant canopy development were best explained by differences in the preceding growing degree day sum. We also observed strong correlations of canopy greenness with the net ecosystem CO2 exchange and ecosystem respiration. On average, vascular plant and moss</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28112825','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28112825"><span>Oxidation of [U-13 C]glucose in the human brain at 7T under steady state conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cheshkov, Sergey; Dimitrov, Ivan E; Jakkamsetti, Vikram; Good, Levi; Kelly, Dorothy; Rajasekaran, Karthik; DeBerardinis, Ralph J; Pascual, Juan M; Sherry, A Dean; Malloy, Craig R</p> <p>2017-12-01</p> <p>Disorders of brain energy metabolism and neurotransmitter recycling have been implicated in multiple neurological conditions. 13 C magnetic resonance spectroscopy ( 13 C MRS) during intravenous administration of 13 C-labeled compounds has been used to measure turnover rates of brain metabolites. This approach, however, requires prolonged infusion inside the magnet. Proton decoupling is typically required but may be difficult to implement with standard equipment. We examined an alternative approach to monitor glucose metabolism in the human brain. 13 C-enriched glucose was infused in healthy subjects outside the magnet to a steady-state level of 13 C enrichment. Subsequently, the subjects were scanned at 7T for 60 min without 1 H decoupling. Metabolic modeling was used to calculate anaplerosis. Biomarkers of energy metabolism and anaplerosis were detected. The glutamate C5 doublet provided information about glucose-derived acetyl-coenzyme A <span class="hlt">flux</span> into the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span> via pyruvate dehydrogenase, and the bicarbonate signal reflected overall <span class="hlt">TCA</span> <span class="hlt">cycle</span> activity. The glutamate C1/C5 ratio is sensitive to anaplerosis. Brain 13 C MRS at 7T provides information about glucose oxidation and anaplerosis without the need of prolonged 13 C infusions inside the scanner and without technical challenges of 1 H decoupling, making it a feasible approach for clinical research. Magn Reson Med 78:2065-2071, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18556786','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18556786"><span>Fur-dependent detoxification of organic acids by rpoS mutants during prolonged incubation under aerobic, phosphate starvation conditions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guillemet, Mélanie L; Moreau, Patrice L</p> <p>2008-08-01</p> <p>The activity of amino acid-dependent acid resistance systems allows Escherichia coli to survive during prolonged incubation under phosphate (P(i)) starvation conditions. We show in this work that rpoS-null mutants incubated in the absence of any amino acid survived during prolonged incubation under aerobic, P(i) starvation conditions. Whereas rpoS(+) cells incubated with glutamate excreted high levels of acetate, rpoS mutants grew on acetic acid. The characteristic metabolism of rpoS mutants required the activity of Fur (ferric uptake regulator) in order to decrease the synthesis of the small RNA RyhB that might otherwise inhibit the synthesis of iron-rich proteins. We propose that RpoS (sigma(S)) and the small RNA RyhB contribute to decrease the synthesis of iron-rich proteins required for the activity of the tricarboxylic acid (<span class="hlt">TCA</span>) <span class="hlt">cycle</span>, which redirects the metabolic <span class="hlt">flux</span> toward the production of acetic acid at the onset of stationary phase in rpoS(+) cells. In contrast, Fur activity, which represses ryhB, and the lack of RpoS activity allow a substantial activity of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> to continue in stationary phase in rpoS mutants, which decreases the production of acetic acid and, eventually, allows growth on acetic acid and P(i) excreted into the medium. These data may help explain the fact that a high frequency of E. coli rpoS mutants is found in nature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28842682','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28842682"><span>Solar Open <span class="hlt">Flux</span> Migration from Pole to Pole: Magnetic Field Reversal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, G-H; Lin, C-H; Lee, L C</p> <p>2017-08-25</p> <p>Coronal holes are solar regions with low soft X-ray or low extreme ultraviolet intensities. The magnetic fields from coronal holes extend far away from the Sun, and thus they are identified as regions with open magnetic field lines. Coronal holes are concentrated in the polar regions during the sunspot minimum phase, and spread to lower latitude during the rising phase of solar activity. In this work, we identify coronal holes with outward and inward open magnetic <span class="hlt">fluxes</span> being in the opposite poles during solar quiet period. We find that during the sunspot rising phase, the outward and inward open <span class="hlt">fluxes</span> perform pole-to-pole trans-equatorial migrations in opposite directions. The migration of the open <span class="hlt">fluxes</span> consists of three parts: open <span class="hlt">flux</span> areas migrating across the equator, new open <span class="hlt">flux</span> areas generated in the low latitude and migrating poleward, and new open <span class="hlt">flux</span> areas locally generated in the polar region. All three components contribute to the reversal of magnetic polarity. The percentage of contribution from each component is different for different solar <span class="hlt">cycle</span>. Our results also show that the sunspot number is positively correlated with the lower-latitude open magnetic <span class="hlt">flux</span> area, but negatively correlated with the total open <span class="hlt">flux</span> area.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2686S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2686S"><span>Model Estimated GCR Particle <span class="hlt">Flux</span> Variation - Assessment with CRIS Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Saganti, Premkumar</p> <p></p> <p>We present model calculated particle <span class="hlt">flux</span> as a function of time during the current solar <span class="hlt">cycle</span> along with the comparisons from the ACE/CRIS data and the Mars/MARIE data. In our model calculations we make use of the NASA's HZETRN (High Z and Energy Transport) code along with the nuclear fragmentation cross sections that are described by the quantum multiple scattering (QMSFRG) model. The time dependant variation of the GCR environment is derived making use of the solar modulation potential, phi. For the past ten years, Advanced Composition Explorer (ACE) has been in orbit at the Sun- Earth libration point (L1). Data from the Cosmic Ray Isotope Spectrometer (CRIS) instrument onboard the ACE spacecraft has been available from 1997 through the present time. Our model calculated particle <span class="hlt">flux</span> showed high degree of correlation during the earlier phase of the current solar <span class="hlt">cycle</span> (2003) in the lower Z region within 15</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.A33M..04H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.A33M..04H"><span>An Analysis of Inter-annual Variability and Uncertainty of Continental Surface Heat <span class="hlt">Fluxes</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, S. Y.; Deng, Y.; Wang, J.</p> <p>2016-12-01</p> <p>The inter-annual variability and the corresponding uncertainty of land surface heat <span class="hlt">fluxes</span> during the first decade of the 21st century are re-evaluated at continental scale based on the heat <span class="hlt">fluxes</span> estimated by the maximum entropy production (MEP) model. The MEP model predicted heat <span class="hlt">fluxes</span> are constrained by surface radiation <span class="hlt">fluxes</span>, automatically satisfy surface energy balance, and are independent of temperature/moisture gradient, wind speed, and roughness lengths. The surface radiation <span class="hlt">fluxes</span> and temperature data from Clouds and the Earth's Radiant Energy System and the surface specific humidity data from Modern-Era Retrospective analysis for Research and Applications were used to reproduce the global surface heat <span class="hlt">fluxes</span> with land-cover data from the NASA Energy and Water <span class="hlt">cycle</span> Study (NEWS). Our analysis shows that the annual means of continental latent heat <span class="hlt">fluxes</span> have increasing trends associated with increasing trends in surface net radiative <span class="hlt">fluxes</span>. The sensible heat <span class="hlt">fluxes</span> also have increasing trends over most continents except for South America. Ground heat <span class="hlt">fluxes</span> have little trends. The continental-scale analysis of the MEP <span class="hlt">fluxes</span> are compared with other existing global surface <span class="hlt">fluxes</span> data products and the implications of the results for inter-annual to decadal variability of regional surface energy budget are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DyAtO..80...47D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DyAtO..80...47D"><span>An assessment of Trop<span class="hlt">Flux</span> and NCEP air-sea <span class="hlt">fluxes</span> on ROMS simulations over the Bay of Bengal region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dey, Dipanjan; Sil, Sourav; Jana, Sudip; Pramanik, Saikat; Pandey, P. C.</p> <p>2017-12-01</p> <p>This study presents an assessment of the Trop<span class="hlt">Flux</span> and the National Centers for Environmental Prediction (NCEP) reanalysis air-sea <span class="hlt">fluxes</span> in simulating the surface and subsurface oceanic parameters over the Bay of Bengal (BoB) region during 2002-2014 using the Regional Ocean Modelling System (ROMS). The assessment has been made by comparing the simulated fields with in-situ and satellite observations. The simulated surface and subsurface temperatures in the Trop<span class="hlt">Flux</span> forced experiment (Trop<span class="hlt">Flux</span>-E) show better agreement with the Research Moored Array for African-Asian-Australian Monsoon Analysis (RAMA) and Argo observations than the NCEP forced experiment (NCEP-E). The BoB domain averaged sea surface temperature (SST) simulated in the NCEP-E is consistently cooler than the satellite SST, with a root mean square error (RMSE) of 0.79 °C. Moreover, NCEP-E shows a limitation in simulating the observed seasonal <span class="hlt">cycle</span> of the SST due to substantial underestimation of the pre-monsoon SST peak. These limitations are mostly due to the lower values of the NCEP net heat <span class="hlt">flux</span>. The seasonal and interannual variations of SST in the Trop<span class="hlt">Flux</span>-E are better comparable to the observations with correlations and skills more than 0.80 and 0.90 respectively. However, SST is overestimated during summer monsoon periods mainly due to higher net heat <span class="hlt">flux</span>. The superiority of Trop<span class="hlt">Flux</span> forcing over the NCEP reanalysis can also be seen when simulating the interannual variabilities of the magnitude and vertical extent of Wyrtki jets at two equatorial RAMA buoy locations. The jet is weaker in the NCEP-E relative to the Trop<span class="hlt">Flux</span>-E and observations. The simulated sea surface height anomalies (SSHA) from both the experiments are able to capture the regions of positive and negative SSHA with respect to satellite-derived altimeter data with better performance in the Trop<span class="hlt">Flux</span>-E. The speed of the westward propagating Rossby wave along 18°N in the Trop<span class="hlt">Flux</span>-E is found to be about 4.7 cm/s, which is close to</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25377990','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25377990"><span>A <span class="hlt">flux</span>-gradient system for simultaneous measurement of the CH4, CO2, and H2O <span class="hlt">fluxes</span> at a lake-air interface.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xiao, Wei; Liu, Shoudong; Li, Hanchao; Xiao, Qitao; Wang, Wei; Hu, Zhenghua; Hu, Cheng; Gao, Yunqiu; Shen, Jing; Zhao, Xiaoyan; Zhang, Mi; Lee, Xuhui</p> <p>2014-12-16</p> <p>Inland lakes play important roles in water and greenhouse gas <span class="hlt">cycling</span> in the environment. This study aims to test the performance of a <span class="hlt">flux</span>-gradient system for simultaneous measurement of the <span class="hlt">fluxes</span> of water vapor, CO2, and CH4 at a lake-air interface. The concentration gradients over the water surface were measured with an analyzer based on the wavelength-scanned cavity ring-down spectroscopy technology, and the eddy diffusivity was measured with a sonic anemometer. Results of a zero-gradient test indicate a <span class="hlt">flux</span> measurement precision of 4.8 W m(-2) for water vapor, 0.010 mg m(-2) s(-1) for CO2, and 0.029 μg m(-2) s(-1) for CH4. During the 620 day measurement period, 97%, 69%, and 67% of H2O, CO2, and CH4 hourly <span class="hlt">fluxes</span> were higher in magnitude than the measurement precision, which confirms that the <span class="hlt">flux</span>-gradient system had adequate precision for the measurement of the lake-air exchanges. This study illustrates four strengths of the <span class="hlt">flux</span>-gradient method: (1) the ability to simultaneously measure the <span class="hlt">flux</span> of H2O, CO2, and CH4; (2) negligibly small density corrections; (3) the ability to resolve small CH4 gradient and <span class="hlt">flux</span>; and (4) continuous and noninvasive operation. The annual mean CH4 <span class="hlt">flux</span> (1.8 g CH4 m(-2) year(-1)) at this hypereutrophic lake was close to the median value for inland lakes in the world (1.6 g CH4 m(-2) year(-1)). The system has adequate precision for CH4 <span class="hlt">flux</span> for broad applications but requires further improvement to resolve small CO2 <span class="hlt">flux</span> in many lakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JInst...6C2054R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JInst...6C2054R"><span>Micro<span class="hlt">TCA</span>-based Global Trigger Upgrade project for the CMS experiment at LHC</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rahbaran, B.; Arnold, B.; Bergauer, H.; Eichberger, M.; Rabady, D.</p> <p>2011-12-01</p> <p>The electronics of the first Level Global Trigger (GT) of CMS is the last stage of the Level-1 trigger system [1]. At LHC up to 40 million collisions of proton bunches occur every second, resulting in about 800 million proton collisions. The CMS Level-1 Global Trigger [1], a custom designed electronics system based on FPGA technology and the VMEbus system, performs a quick on-line analysis of each collision every 25 ns and decides whether to reject or to accept it for further analysis. The CMS trigger group of the Institute of High Energy Physics in Vienna (HEPHY) is involved in the Level-1 trigger of the CMS experiment at CERN. As part of the Trigger Upgrade, the Level-1 Global Trigger will be redesigned and implemented in Micro<span class="hlt">TCA</span> based technology, which allows engineers to detect all possible faults on plug-in boards, in the power supply and in the cooling system. The upgraded Global Trigger will be designed to have the same basic categories of functions as the present GT, but will have more algorithms and more possibilities for combining trigger candidates. Additionally, reconfigurability and testability will be supported based on the next system generation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110007277','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110007277"><span><span class="hlt">Flux</span> Transport and the Sun's Global Magnetic Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hathaway, David H.</p> <p>2010-01-01</p> <p>The Sun s global magnetic field is produced and evolved through the emergence of magnetic <span class="hlt">flux</span> in active regions and its transport across the solar surface by the axisymmetric differential rotation and meridional flow and the non-axisymmetric convective flows of granulation, supergranulation, and giant cell convection. Maps of the global magnetic field serve as the inner boundary condition for space weather. The photospheric magnetic field and its evolution determine the coronal and solar wind structures through which CMEs must propagate and in which solar energetic particles are accelerated and propagate. Producing magnetic maps which best represent the actual field configuration at any instant requires knowing the magnetic field over the observed hemisphere as well as knowing the flows that transport <span class="hlt">flux</span>. From our Earth-based vantage point we only observe the front-side hemisphere and each pole is observable for only six months of the year at best. Models for the surface magnetic <span class="hlt">flux</span> transport can be used to provide updates to the magnetic field configuration in those unseen regions. In this presentation I will describe successes and failures of surface <span class="hlt">flux</span> transport and present new observations on the structure, the solar <span class="hlt">cycle</span> variability, and the evolution of the flows involved in magnetic <span class="hlt">flux</span> transport. I find that supergranules play the dominant role due to their strong flow velocities and long lifetimes. <span class="hlt">Flux</span> is transported by differential rotation and meridional flow only to the extent that the supergranules participate in those two flows.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28600876','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28600876"><span>Rerouting of carbon <span class="hlt">flux</span> in a glycogen mutant of cyanobacteria assessed via isotopically non-stationary 13 C metabolic <span class="hlt">flux</span> analysis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hendry, John I; Prasannan, Charulata; Ma, Fangfang; Möllers, K Benedikt; Jaiswal, Damini; Digmurti, Madhuri; Allen, Doug K; Frigaard, Niels-Ulrik; Dasgupta, Santanu; Wangikar, Pramod P</p> <p>2017-10-01</p> <p>Cyanobacteria, which constitute a quantitatively dominant phylum, have attracted attention in biofuel applications due to favorable physiological characteristics, high photosynthetic efficiency and amenability to genetic manipulations. However, quantitative aspects of cyanobacterial metabolism have received limited attention. In the present study, we have performed isotopically non-stationary 13 C metabolic <span class="hlt">flux</span> analysis (INST- 13 C-MFA) to analyze rerouting of carbon in a glycogen synthase deficient mutant strain (glgA-I glgA-II) of the model cyanobacterium Synechococcus sp. PCC 7002. During balanced photoautotrophic growth, 10-20% of the fixed carbon is stored in the form of glycogen via a pathway that is conserved across the cyanobacterial phylum. Our results show that deletion of glycogen synthase gene orchestrates cascading effects on carbon distribution in various parts of the metabolic network. Carbon that was originally destined to be incorporated into glycogen gets partially diverted toward alternate storage molecules such as glucosylglycerol and sucrose. The rest is partitioned within the metabolic network, primarily via glycolysis and tricarboxylic acid <span class="hlt">cycle</span>. A lowered <span class="hlt">flux</span> toward carbohydrate synthesis and an altered distribution at the glucose-1-phosphate node indicate flexibility in the network. Further, reversibility of glycogen biosynthesis reactions points toward the presence of futile <span class="hlt">cycles</span>. Similar redistribution of carbon was also predicted by <span class="hlt">Flux</span> Balance Analysis. The results are significant to metabolic engineering efforts with cyanobacteria where fixed carbon needs to be re-routed to products of interest. Biotechnol. Bioeng. 2017;114: 2298-2308. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5586201','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5586201"><span>CO2 <span class="hlt">flux</span> from Javanese mud volcanism</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Burton, M. R.; Arzilli, F.; Chiarugi, A.; Marliyani, G. I.; Anggara, F.; Harijoko, A.</p> <p>2017-01-01</p> <p>Abstract Studying the quantity and origin of CO2 emitted by back‐arc mud volcanoes is critical to correctly model fluid‐dynamical, thermodynamical, and geochemical processes that drive their activity and to constrain their role in the global geochemical carbon <span class="hlt">cycle</span>. We measured CO2 <span class="hlt">fluxes</span> of the Bledug Kuwu mud volcano on the Kendeng Fold and thrust belt in the back arc of Central Java, Indonesia, using scanning remote sensing absorption spectroscopy. The data show that the expelled gas is rich in CO2 with a volume fraction of at least 16 vol %. A lower limit CO2 <span class="hlt">flux</span> of 1.4 kg s−1 (117 t d−1) was determined, in line with the CO2 <span class="hlt">flux</span> from the Javanese mud volcano LUSI. Extrapolating these results to mud volcanism from the whole of Java suggests an order of magnitude total CO2 <span class="hlt">flux</span> of 3 kt d−1, comparable with the expected back‐arc efflux of magmatic CO2. After discussing geochemical, geological, and geophysical evidence we conclude that the source of CO2 observed at Bledug Kuwu is likely a mixture of thermogenic, biogenic, and magmatic CO2, with faulting controlling potential pathways for magmatic fluids. This study further demonstrates the merit of man‐portable active remote sensing instruments for probing natural gas releases, enabling bottom‐up quantification of CO2 <span class="hlt">fluxes</span>. PMID:28944134</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740007949','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740007949"><span>Radiation environment for ATS-F. [including ambient trapped particle <span class="hlt">fluxes</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Stassinopoulos, E. G.</p> <p>1974-01-01</p> <p>The ambient trapped particle <span class="hlt">fluxes</span> incident on the ATS-F satellite were determined. Several synchronous circular flight paths were evaluated and the effect of parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital <span class="hlt">flux</span> integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton <span class="hlt">fluxes</span> are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar <span class="hlt">cycle</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18...26B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18...26B"><span>Calibration of Ocean Forcing with satellite <span class="hlt">Flux</span> Estimates (COFFEE)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barron, Charlie; Jan, Dastugue; Jackie, May; Rowley, Clark; Smith, Scott; Spence, Peter; Gremes-Cordero, Silvia</p> <p>2016-04-01</p> <p>Predicting the evolution of ocean temperature in regional ocean models depends on estimates of surface heat <span class="hlt">fluxes</span> and upper-ocean processes over the forecast period. Within the COFFEE project (Calibration of Ocean Forcing with satellite <span class="hlt">Flux</span> Estimates, real-time satellite observations are used to estimate shortwave, longwave, sensible, and latent air-sea heat <span class="hlt">flux</span> corrections to a background estimate from the prior day's regional or global model forecast. These satellite-corrected <span class="hlt">fluxes</span> are used to prepare a corrected ocean hindcast and to estimate <span class="hlt">flux</span> error covariances to project the heat <span class="hlt">flux</span> corrections for a 3-5 day forecast. In this way, satellite remote sensing is applied to not only inform the initial ocean state but also to mitigate errors in surface heat <span class="hlt">flux</span> and model representations affecting the distribution of heat in the upper ocean. While traditional assimilation of sea surface temperature (SST) observations re-centers ocean models at the start of each forecast <span class="hlt">cycle</span>, COFFEE endeavors to appropriately partition and reduce among various surface heat <span class="hlt">flux</span> and ocean dynamics sources. A suite of experiments in the southern California Current demonstrates a range of COFFEE capabilities, showing the impact on forecast error relative to a baseline three-dimensional variational (3DVAR) assimilation using operational global or regional atmospheric forcing. Experiment cases combine different levels of <span class="hlt">flux</span> calibration with assimilation alternatives. The cases use the original <span class="hlt">fluxes</span>, apply full satellite corrections during the forecast period, or extend hindcast corrections into the forecast period. Assimilation is either baseline 3DVAR or standard strong-constraint 4DVAR, with work proceeding to add a 4DVAR expanded to include a weak constraint treatment of the surface <span class="hlt">flux</span> errors. Covariance of <span class="hlt">flux</span> errors is estimated from the recent time series of forecast and calibrated <span class="hlt">flux</span> terms. While the California Current examples are shown, the approach is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26417080','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26417080"><span>Orbital pacing of carbon <span class="hlt">fluxes</span> by a ∼9-My eccentricity <span class="hlt">cycle</span> during the Mesozoic.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Martinez, Mathieu; Dera, Guillaume</p> <p>2015-10-13</p> <p>Eccentricity, obliquity, and precession are cyclic parameters of the Earth's orbit whose climatic implications have been widely demonstrated on recent and short time intervals. Amplitude modulations of these parameters on million-year time scales induce "grand orbital <span class="hlt">cycles</span>," but the behavior and the paleoenvironmental consequences of these <span class="hlt">cycles</span> remain debated for the Mesozoic owing to the chaotic diffusion of the solar system in the past. Here, we test for these <span class="hlt">cycles</span> from the Jurassic to the Early Cretaceous by analyzing new stable isotope datasets reflecting fluctuations in the carbon <span class="hlt">cycle</span> and seawater temperatures. Our results document a prominent cyclicity of ∼9 My in the carbon <span class="hlt">cycle</span> paced by changes in the seasonal dynamics of hydrological processes and long-term sea level fluctuations. These paleoenvironmental changes are linked to a great eccentricity <span class="hlt">cycle</span> consistent with astronomical solutions. The orbital forcing signal was mainly amplified by cumulative sequestration of organic matter in the boreal wetlands under greenhouse conditions. Finally, we show that the ∼9-My <span class="hlt">cycle</span> faded during the Pliensbachian, which could either reflect major paleoenvironmental disturbances or a chaotic transition affecting this <span class="hlt">cycle</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4611626','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4611626"><span>Orbital pacing of carbon <span class="hlt">fluxes</span> by a ∼9-My eccentricity <span class="hlt">cycle</span> during the Mesozoic</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Martinez, Mathieu; Dera, Guillaume</p> <p>2015-01-01</p> <p>Eccentricity, obliquity, and precession are cyclic parameters of the Earth’s orbit whose climatic implications have been widely demonstrated on recent and short time intervals. Amplitude modulations of these parameters on million-year time scales induce ‟grand orbital <span class="hlt">cycles</span>,” but the behavior and the paleoenvironmental consequences of these <span class="hlt">cycles</span> remain debated for the Mesozoic owing to the chaotic diffusion of the solar system in the past. Here, we test for these <span class="hlt">cycles</span> from the Jurassic to the Early Cretaceous by analyzing new stable isotope datasets reflecting fluctuations in the carbon <span class="hlt">cycle</span> and seawater temperatures. Our results document a prominent cyclicity of ∼9 My in the carbon <span class="hlt">cycle</span> paced by changes in the seasonal dynamics of hydrological processes and long-term sea level fluctuations. These paleoenvironmental changes are linked to a great eccentricity <span class="hlt">cycle</span> consistent with astronomical solutions. The orbital forcing signal was mainly amplified by cumulative sequestration of organic matter in the boreal wetlands under greenhouse conditions. Finally, we show that the ∼9-My <span class="hlt">cycle</span> faded during the Pliensbachian, which could either reflect major paleoenvironmental disturbances or a chaotic transition affecting this <span class="hlt">cycle</span>. PMID:26417080</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11543132','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11543132"><span>Solar <span class="hlt">cycle</span> variations of MIR radiation environment as observed by the LIULIN dosimeter.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dachev TsP; Tomov, B T; Matviichuk YuN; Koleva, R T; Semkova, J V; Petrov, V M; Benghin, V V; Ivanov YuV; Shurshakov, V A; Lemaire, J F</p> <p>1999-06-01</p> <p>Measurements on board the MIR space station by the Bulgarian-Russian dosimeter LIULIN have been used to study the solar <span class="hlt">cycle</span> variations of the radiation environment. The fixed locations of the instrument in the MIR manned compartment behind 6-15 g/cm2 of shielding have given homogeneous series of particle <span class="hlt">fluxes</span> and doses measurements to be collected during the declining phase of 22nd solar <span class="hlt">cycle</span> between September 1989 and April 1994. During the declining phase of 22nd solar <span class="hlt">cycle</span> the GCR (Galactic Cosmic Rays) <span class="hlt">flux</span> observed at L>4 (where L is the McIlwain parameter) has enhanced from 0.6-0.7 cm-2 s-1 up to 1.4-1.6 cm-2 s-1. The long-term observations of the trapped radiation can be summarized as follows: the main maximum of the <span class="hlt">flux</span> and dose rate is located at the southeast side of the geomagnetic field minimum of South Atlantic Anomaly (SAA) at L=1.3-1.4. Protons depositing few (nGy cm2)/particle in the detector predominantly populate this region. At practically the same spatial location and for similar conditions the dose rate rises up from 480 to 1470 microGy/h dose in silicon in the 1990-1994 time interval, during the declining phase of the solar <span class="hlt">cycle</span>. On the other hand the <span class="hlt">flux</span> rises from 35 up to 115 cm-2 s-1 for the same period of time. A power law dependence was extracted which predicts that when the total neutral density at the altitude of the station decreases from 8x10(-15) to 6x10(-16) g/cm3 the dose increase from about 200 microGy/h up to 1200 microGy/h. At the same time the <span class="hlt">flux</span> increase from about 30 cm-2 s-1 up to 120 cm-2 s-1. The AP8 model predictions give only 5.8% increase of the <span class="hlt">flux</span> for the same conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4267523','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4267523"><span>The role of the mitochondrial pyruvate carrier in substrate regulation</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vacanti, Nathaniel M.; Divakaruni, Ajit S.; Green, Courtney R.; Parker, Seth J.; Henry, Robert R.; Ciaraldi, Theodore P.; Murphy, Anne N.; Metallo, Christian M.</p> <p>2014-01-01</p> <p>SUMMARY Pyruvate lies at a central biochemical node connecting carbohydrate, amino acid, and fatty acid metabolism, and the regulation of pyruvate <span class="hlt">flux</span> into mitochondria represents a critical step in intermediary metabolism impacting numerous diseases. To characterize changes in mitochondrial substrate utilization in the context of compromised mitochondrial pyruvate transport, we applied 13C metabolic <span class="hlt">flux</span> analysis (MFA) to cells after transcriptional or pharmacological inhibition of the mitochondrial pyruvate carrier (MPC). Despite profound suppression of both glucose and pyruvate oxidation, cell growth, oxygen consumption, and tricarboxylic acid (<span class="hlt">TCA</span>) metabolism were surprisingly maintained. Oxidative <span class="hlt">TCA</span> <span class="hlt">flux</span> was achieved through enhanced reliance on glutaminolysis through malic enzyme and pyruvate dehydrogenase (PDH) as well as fatty acid and branched chain amino acid oxidation. Thus, in contrast to inhibition of complex I or PDH, suppression of pyruvate transport induces a form of metabolic flexibility associated with use of lipids and amino acids as catabolic and anabolic fuels. PMID:25458843</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC23K..14F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC23K..14F"><span>Carbon <span class="hlt">fluxes</span> in North American coastal and shelf seas: Current status and trends</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fennel, K.; Alin, S. R.; Barbero, L.; Evans, W.; Martin Hernandez-Ayon, J. M.; Hu, X.; Lohrenz, S. E.; Muller-Karger, F. E.; Najjar, R.; Robbins, L. L.; Shadwick, E. H.; Siedlecki, S. A.; Steiner, N.; Turk, D.; Vlahos, P.; Wang, A. Z.</p> <p>2016-12-01</p> <p>Coastal and shelf seas represent an interface between all major components of the global carbon <span class="hlt">cycle</span>: land, atmosphere, marine sediments and the ocean. <span class="hlt">Fluxes</span> and transformations of carbon in coastal systems are complex and highly variable in space and time. The First State of the Carbon <span class="hlt">Cycle</span> Report (http://cdiac.ornl.gov/SOCCR/final.html, Chapter 15, Chavez et al. 2007) concluded that carbon budgets of North American ocean margins were not well quantified because of insufficient observations and the complexity and highly localized spatial variability of coastal carbon dynamics. Since then significant progress has been made through the expansion of carbon observing networks, the implementation of modeling capabilities, and national and international coordination and synthesis activities. We will review the current understanding of coastal carbon <span class="hlt">fluxes</span> around the North American continent including along the Atlantic and Pacific coasts, the northern Gulf of Mexico, and the North American Arctic region and provide a compilation of regional estimates of air-sea <span class="hlt">fluxes</span> of CO2. We will discuss generalizable patterns in coastal air-sea CO2 exchange and other carbon <span class="hlt">fluxes</span> as well as reasons underlying spatial heterogeneity. After providing an overview of the principal modes of carbon export from coastal systems, we will apply these mechanisms to the North American continent, and discuss observed and projected trends of key properties and <span class="hlt">fluxes</span>. The presentation will illustrate that despite significant advances in capabilities and understanding, large uncertainties remain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.1410B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.1410B"><span>Estimation of Throughfall and Stemflow Bacterial <span class="hlt">Flux</span> in a Subtropical Oak-Cedar Forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bittar, Thais B.; Pound, Preston; Whitetree, Ansley; Moore, L. Dean; Van Stan, John T.</p> <p>2018-02-01</p> <p>Transport pathways of microbes between ecosystem spheres (atmosphere, phyllosphere, and pedosphere) represent major <span class="hlt">fluxes</span> in nutrient <span class="hlt">cycles</span> and have the potential to affect microbially mediated biogeochemical processes. Novel data on bacterial <span class="hlt">fluxes</span> from the phyllosphere to the pedosphere during rainfall via throughfall (rain dripping from/through the canopy) and stemflow (rain funneled down tree stems) are reported. Bacterial concentrations were quantified using flow cytometry and validated with quantitative polymerase chain reaction assays in rainfall samples from an oak-cedar forest in coastal Georgia (southeastern U.S.). Bacteria concentrations (cells mL-1) and storm-normalized <span class="hlt">fluxes</span> (cells m-2 h-1, cells m-2 mm-1) were greater for cedar versus oak. Total bacterial <span class="hlt">flux</span> was 1.5 × 1016 cells ha-1 yr-1. These previously unexamined bacterial <span class="hlt">fluxes</span> are interpreted in the context of major elemental pools and <span class="hlt">fluxes</span> in forests and could represent inoculum-level sources of bacteria (if alive), and organic matter and inorganic solute inputs (if lysed) to soils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018BGeo...15.3143K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018BGeo...15.3143K"><span>Landscape analysis of soil methane <span class="hlt">flux</span> across complex terrain</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kaiser, Kendra E.; McGlynn, Brian L.; Dore, John E.</p> <p>2018-05-01</p> <p>Relationships between methane (CH4) <span class="hlt">fluxes</span> and environmental conditions have been extensively explored in saturated soils, while research has been less prevalent in aerated soils because of the relatively small magnitudes of CH4 <span class="hlt">fluxes</span> that occur in dry soils. Our study builds on previous carbon <span class="hlt">cycle</span> research at Tenderfoot Creek Experimental Forest, Montana, to identify how environmental conditions reflected by topographic metrics can be leveraged to estimate watershed scale CH4 <span class="hlt">fluxes</span> from point scale measurements. Here, we measured soil CH4 concentrations and <span class="hlt">fluxes</span> across a range of landscape positions (7 riparian, 25 upland), utilizing topographic and seasonal (29 May-12 September) gradients to examine the relationships between environmental variables, hydrologic dynamics, and CH4 emission and uptake. Riparian areas emitted small <span class="hlt">fluxes</span> of CH4 throughout the study (median: 0.186 µg CH4-C m-2 h-1) and uplands increased in sink strength with dry-down of the watershed (median: -22.9 µg CH4-C m-2 h-1). Locations with volumetric water content (VWC) below 38 % were methane sinks, and uptake increased with decreasing VWC. Above 43 % VWC, net CH4 efflux occurred, and at intermediate VWC net <span class="hlt">fluxes</span> were near zero. Riparian sites had near-neutral cumulative seasonal <span class="hlt">flux</span>, and cumulative uptake of CH4 in the uplands was significantly related to topographic indices. These relationships were used to model the net seasonal CH4 <span class="hlt">flux</span> of the upper Stringer Creek watershed (-1.75 kg CH4-C ha-1). This spatially distributed estimate was 111 % larger than that obtained by simply extrapolating the mean CH4 <span class="hlt">flux</span> to the entire watershed area. Our results highlight the importance of quantifying the space-time variability of net CH4 <span class="hlt">fluxes</span> as predicted by the frequency distribution of landscape positions when assessing watershed scale greenhouse gas balances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840016704','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840016704"><span>Performance of thermal barrier coatings in high heat <span class="hlt">flux</span> environments</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Miller, R. A.; Berndt, C. C.</p> <p>1984-01-01</p> <p>Thermal barrier coatings were exposed to the high temperature and high heat <span class="hlt">flux</span> produced by a 30 kW plasma torch. Analysis of the specimen heating rates indicates that the temperature drop across the thickness of the 0.038 cm ceramic layer was about 1100 C after 0.5 sec in the flame. An as-sprayed ZrO2-8%Y2O3 specimens survived 3000 of the 0.5 sec <span class="hlt">cycles</span> with failing. Surface spalling was observed when 2.5 sec <span class="hlt">cycles</span> were employed but this was attributed to uneven heating caused by surface roughness. This surface spalling was prevented by smoothing the surface with silicon carbide paper or by laser glazing. A coated specimen with no surface modification but which was heat treated in argon also did not surface spall. Heat treatment in air led to spalling in as early as 2 <span class="hlt">cycle</span> from heating stresses. Failures at edges were investigated and shown to be a minor source of concern. Ceramic coatings formed from ZrO2-12%Y2O3 or ZrO2-20%Y2O3 were shown to be unsuited for use under the high heat <span class="hlt">flux</span> conditions of this study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26344101','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26344101"><span>Loss of Mitochondrial Pyruvate Carrier 2 in the Liver Leads to Defects in Gluconeogenesis and Compensation via Pyruvate-Alanine <span class="hlt">Cycling</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>McCommis, Kyle S; Chen, Zhouji; Fu, Xiaorong; McDonald, William G; Colca, Jerry R; Kletzien, Rolf F; Burgess, Shawn C; Finck, Brian N</p> <p>2015-10-06</p> <p>Pyruvate transport across the inner mitochondrial membrane is believed to be a prerequisite for gluconeogenesis in hepatocytes, which is important for the maintenance of normoglycemia during prolonged food deprivation but also contributes to hyperglycemia in diabetes. To determine the requirement for mitochondrial pyruvate import in gluconeogenesis, mice with liver-specific deletion of mitochondrial pyruvate carrier 2 (LS-Mpc2(-/-)) were generated. Loss of MPC2 impaired, but did not completely abolish, hepatocyte conversion of labeled pyruvate to <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates and glucose. Unbiased metabolomic analyses of livers from fasted LS-Mpc2(-/-) mice suggested that alterations in amino acid metabolism, including pyruvate-alanine <span class="hlt">cycling</span>, might compensate for the loss of MPC2. Indeed, inhibition of pyruvate-alanine transamination further reduced mitochondrial pyruvate metabolism and glucose production by LS-Mpc2(-/-) hepatocytes. These data demonstrate an important role for MPC2 in controlling hepatic gluconeogenesis and illuminate a compensatory mechanism for circumventing a block in mitochondrial pyruvate import. Copyright © 2015 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.uwlax.edu/biology/faculty/Strauss/Reprints/Dodds%20et%20al%20(2000).pdf','USGSPUBS'); return false;" href="http://www.uwlax.edu/biology/faculty/Strauss/Reprints/Dodds%20et%20al%20(2000).pdf"><span>Quantification of the nitrogen <span class="hlt">cycle</span> in a prairie stream</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Dodds, Walter K.; Evans-White, Michelle A.; Gerlanc, Nicole M.; Gray, Lawrence; Gudder, Dolly A.; Kemp, Melody J.; Lopez, Amanda L.; Stagliano, David; Strauss, Eric A.; Tank, Jennifer L.; Whiles, Matt R.; Wollheim, Wilfred M.</p> <p>2000-01-01</p> <p>Nitrogen (N) was added for 35 days in the form of 15NH4Cl to Kings Creek on Konza Prairie, Kansas. Standing stocks of N in key compartments (that is, nutrients, detritus, organisms) were quantified, and the amount of labeled N entering the compartments was analyzed. These data were used to calculate turnover and <span class="hlt">flux</span> rates of N <span class="hlt">cycling</span> through the food web, as well as nutrient transformation rates. Inorganic N pools turned over much more rapidly in the water column of this stream than in pelagic systems where comparable measurements have been made. As with other systems, the mass of ammonium was low but it was the key compartment mediating nutrient <span class="hlt">flux</span> through the ecosystem, whereas dissolved organic N, the primary component of N <span class="hlt">flux</span> through the system, is not actively <span class="hlt">cycled</span>. Nitrification was also a significant <span class="hlt">flux</span> of N in the stream, with rates in the water column and surface of benthos accounting for approximately 10% of the total ammonium uptake. Primary consumers assimilated 67% of the inorganic N that entered benthic algae and microbes. Predators acquired 23% of the N that consumers obtained. Invertebrate collectors, omnivorous crayfish (Orconectes spp.), and invertebrate shredders dominated the N <span class="hlt">flux</span> associated with primary consumers. Mass balance calculations indicated that at least 23% of the 309 mg of 15N added during the 35 days of release was retained within the 210-m stream reach during the release. Overall, the rates of turnover of N in organisms and organic substrata were significantly greater when C:N was low. This ratio may be a surrogate for biological activity with regard to N <span class="hlt">flux</span> in streams.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGeo...12.3061J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGeo...12.3061J"><span>Lunar periodicity in the shell <span class="hlt">flux</span> of planktonic foraminifera in the Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jonkers, L.; Reynolds, C. E.; Richey, J.; Hall, I. R.</p> <p>2015-05-01</p> <p>Synchronised reproduction offers clear benefits to planktonic foraminifera - an important group of marine calcifiers - as it increases the chances of successful gamete fusion. Such synchrony requires tuning to an internal or external clock. Evidence exists for lunar reproductive <span class="hlt">cycles</span> in some species, but its recognition in shell <span class="hlt">flux</span> time series has proven difficult, raising questions about reproductive strategies. Using spectral analysis of a 4-year time series (mostly at weekly resolution) from the northern Gulf of Mexico, we show that the shell <span class="hlt">flux</span> of Globorotalia menardii, Globigerinella siphonifera, Orbulina universa, Globigerinoides sacculifer, Globigerinoides ruber (both pink and white varieties), Pulleniatina obliquiloculata, Neogloboquadrina dutertrei, Globigerinella calida and Globigerinita glutinata is characterised by lunar periodicity. However, the lunar rhythm is not present in all size fractions of each species and tends to be more dominant in the <span class="hlt">flux</span> of larger shells, consistent with reproduction being more prevalent in larger specimens. Lunar periodicity is superimposed on longer term/seasonal changes in the shell <span class="hlt">fluxes</span>, but accounts for a significant part of the variance in the <span class="hlt">fluxes</span>. The amplitude of the lunar <span class="hlt">cycle</span> increases roughly proportional with the magnitude of the <span class="hlt">flux</span>, demonstrating that most of the population is indeed affected by lunar-phased synchronisation. In most species peak <span class="hlt">fluxes</span> occur predominantly around, or just after, full moon. Only G. siphonifera and G. calida show a contrasting pattern with peaks concentrated around new moon. Although the exact cause of the synchronisation remains elusive, our data considerably increase the number of species for which lunar synchronised reproduction is reported and suggest that such reproductive behaviour is common in many species of planktonic foraminifera.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120013761','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120013761"><span>Periods of High Intensity Solar Proton <span class="hlt">Flux</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.</p> <p>2012-01-01</p> <p>Analysis is presented for times during a space mission that specified solar proton <span class="hlt">flux</span> levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar <span class="hlt">cycle</span> are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950052486&hterms=climate+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dclimate%2Bexchange','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950052486&hterms=climate+exchange&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dclimate%2Bexchange"><span>Radiative <span class="hlt">flux</span> opens new window on climate research</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pinker, R. T.; Laszlo, I.; Whitlock, C. H.; Charlock, T. P.</p> <p>1995-01-01</p> <p>For several decades, global satellite observations have been made of the rate at which electromagnetic energy (radiative <span class="hlt">flux</span>) is emerging from the top of the atmosphere of our planet in the spectral range of about 0.2-50.0 microns. At the same time, models have been developed to infer the radiative <span class="hlt">flux</span> at the surface from the values observed by the satellites at the upper boundary. The balance of incoming and outgoing radiative <span class="hlt">flux</span> (radiation budget) at both boundaries, determines the net gain or loss of the radiative energy within an atmospheric column. Climate researchers can use the radiative <span class="hlt">flux</span> as a tool to validate climate models, separate the radiative impact of clouds from surface and atmosphere contributions, and to understand the global hydrological <span class="hlt">cycle</span>. When applied to physical processes occurring at the surface, information on the radiative <span class="hlt">flux</span> has the potential to substantially advance our understanding of the transport of heat, moisture, and momentum across the surface/atmosphere interface. Geophysicists of many disciplines stand to benefit from efforts to improve the use of this latter untapped resource. Oceanographers can improve the representation of the selective absorption of radiation in the oceans; biologists and ecologists can improve their models for carbon dioxide exchange and biological heating in oceans; agronomists can model more realistically biomass and crop yields; and environmentalists can obtain better assessment of natural resources of radiation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19669466','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19669466"><span>Kinetic model of mitochondrial Krebs <span class="hlt">cycle</span>: unraveling the mechanism of salicylate hepatotoxic effects.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mogilevskaya, Ekaterina; Demin, Oleg; Goryanin, Igor</p> <p>2006-10-01</p> <p>This paper studies the effect of salicylate on the energy metabolism of mitochondria using in silico simulations. A kinetic model of the mitochondrial Krebs <span class="hlt">cycle</span> is constructed using information on the individual enzymes. Model parameters for the rate equations are estimated using in vitro experimental data from the literature. Enzyme concentrations are determined from data on respiration in mitochondrial suspensions containing glutamate and malate. It is shown that inhibition in succinate dehydrogenase and alpha-ketoglutarate dehydrogenase by salicylate contributes substantially to the cumulative inhibition of the Krebs <span class="hlt">cycle</span> by salicylates. Uncoupling of oxidative phosphorylation has little effect and coenzyme A consumption in salicylates transformation processes has an insignificant effect on the rate of substrate oxidation in the Krebs <span class="hlt">cycle</span>. It is found that the salicylate-inhibited Krebs <span class="hlt">cycle</span> <span class="hlt">flux</span> can be increased by <span class="hlt">flux</span> redirection through addition of external glutamate and malate, and depletion in external alpha-ketoglutarate and glycine concentrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.H12E..05N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.H12E..05N"><span>Evaluating the role of sulfur and hyporheic exchange in biogeochemical <span class="hlt">cycling</span> in riparian wetlands</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ng, G. H. C.; O'Hara, P. A.; Santelli, C. M.; Rosenfeld, C.; Yourd, A.</p> <p>2017-12-01</p> <p>Although the mixing of surface water and groundwater is well-recognized to support hotspots of redox activities such as denitrification, few hyporheic zone studies have examined sulfur reactions. Because sulfate concentrations in wetlands, lake beds, and stream beds are low compared to in marine settings, the hierarchical redox tower dictates that sulfate reduction should play a substantially lesser role in biogeochemical <span class="hlt">cycling</span> than nitrate or iron reduction when these sediments become anoxic. However, recent experiments challenge the classically held redox sequence by revealing "cryptic" sulfur <span class="hlt">cycling</span> that can support unexpectedly high sulfate reduction rates and could be driving iron and carbon <span class="hlt">cycling</span> through coupled reactions. Sulfur biogeochemical processes remain poorly understood in field settings, where little is known about the impact of hydrologic <span class="hlt">fluxes</span>. Our study examines how hyporheic <span class="hlt">flux</span> can "kick" forward cryptic sulfur <span class="hlt">cycling</span> and related iron and carbon reactions by perturbing geochemical gradients to which microbial communities respond. We evaluate field-scale <span class="hlt">cycling</span> of iron, sulfur, and carbon through a combination of hydrologic monitoring, microbial and geochemical analyses, and reactive-transport modeling at a riparian wetland site in northeastern Minnesota that is impacted by mining practices. In particular, we assess how varying <span class="hlt">fluxes</span> between high sulfate concentration surface water and lower sulfate concentration groundwater over a season could be (1) facilitating intensified sulfur <span class="hlt">cycling</span> coupled to abiotic iron reduction and (2) altering methane release possibly through anaerobic methane oxidation. Our findings can help clarify the importance of sulfur in non-marine biogeochemical <span class="hlt">cycling</span> and provide better understanding of how anthropogenic activities can impact critical freshwater systems.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24218214','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24218214"><span>Optimal design of isotope labeling experiments.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Hong; Mandy, Dominic E; Libourel, Igor G L</p> <p>2014-01-01</p> <p>Stable isotope labeling experiments (ILE) constitute a powerful methodology for estimating metabolic <span class="hlt">fluxes</span>. An optimal label design for such an experiment is necessary to maximize the precision with which <span class="hlt">fluxes</span> can be determined. But often, precision gained in the determination of one <span class="hlt">flux</span> comes at the expense of the precision of other <span class="hlt">fluxes</span>, and an appropriate label design therefore foremost depends on the question the investigator wants to address. One could liken ILE to shadows that metabolism casts on products. Optimal label design is the placement of the lamp; creating clear shadows for some parts of metabolism and obscuring others.An optimal isotope label design is influenced by: (1) the network structure; (2) the true <span class="hlt">flux</span> values; (3) the available label measurements; and, (4) commercially available substrates. The first two aspects are dictated by nature and constrain any optimal design. The second two aspects are suitable design parameters. To create an optimal label design, an explicit optimization criterion needs to be formulated. This usually is a property of the <span class="hlt">flux</span> covariance matrix, which can be augmented by weighting label substrate cost. An optimal design is found by using such a criterion as an objective function for an optimizer. This chapter uses a simple elementary metabolite units (EMU) representation of the <span class="hlt">TCA</span> <span class="hlt">cycle</span> to illustrate the process of experimental design of isotope labeled substrates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860056628&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Benergy','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860056628&hterms=Magnetic+energy&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Benergy"><span>The cyclical variation of energy <span class="hlt">flux</span> and photospheric magnetic field strength from coronal holes</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Webb, D. F.; Davis, J. M.</p> <p>1985-01-01</p> <p>The average soft X-ray emission from coronal holes observed on images obtained during rocket flights from 1974 to 1981 is measured. The variation of this emission over the solar <span class="hlt">cycle</span> was then compared with photospheric magnetic <span class="hlt">flux</span> measurements within coronal holes over the same period. It was found that coronal hole soft X-ray emission could be detected and that this emission appeared to increase with the rise of the sunspot <span class="hlt">cycle</span> from activity minimum to maximum. These quantitative results confirmed previous suggestions that the coronal brightness contrast between holes and large-scale structure decreased during this period of the <span class="hlt">cycle</span>. Gas pressures at the hole base were estimated for assumed temperatures and found to vary from about 0.03 dyne/sq cm in 1974 to 0.35 dyne/sq cm in 1981. The increase in coronal hole X-ray emission was accompanied by a similar trend in the surface magnetic <span class="hlt">flux</span> of near-equatorial holes between 1975 and 1980 (Harvey et al., 1982).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B21N..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B21N..05R"><span>Freeze-Thaw <span class="hlt">Cycles</span> and Soil Biogeochemistry: Implications for Greenhouse Gas emission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rezanezhad, F.; Milojevic, T.; Oh, D. H.; Parsons, C. T.; Smeaton, C. M.; Van Cappellen, P.</p> <p>2016-12-01</p> <p>Freeze-thaw <span class="hlt">cycles</span> represent a major natural climate forcing acting on soils at middle and high latitudes. Repeated freezing and thawing of soils changes their physical properties, geochemistry, and microbial community structure, which together govern the biogeochemical <span class="hlt">cycling</span> of carbon and nutrients. In this presentation, we focus on how freeze-thaw <span class="hlt">cycles</span> regulate carbon and nitrogen <span class="hlt">cycling</span> and how these transformations influence greenhouse gas (GHG) <span class="hlt">fluxes</span>. We present a novel approach, which combines the acquisition of physical and chemical data in a newly developed experimental soil column system. This system simulates realistic soil temperature profiles during freeze-thaw <span class="hlt">cycles</span>. A high-resolution, Multi-Fiber Optode (MuFO) microsensor technique was used to detect oxygen (O2) continuously in the column at multiple depths. Surface and subsurface changes to gas and aqueous phase chemistry were measured to delineate the pathways and quantify soil respiration rates during freeze-thaw <span class="hlt">cycles</span>. The results indicate that the time-dependent release of GHG from the soil surface is influenced by a combination of two key factors. Firstly, fluctuations in temperature and O2 availability affect soil biogeochemical activity and GHG production. Secondly, the recurrent development of a physical ice barrier prevents exchange of gaseous compounds between the soil and atmosphere during freezing conditions; removal of this barrier during thaw conditions increases GHG <span class="hlt">fluxes</span>. During freezing, O2 levels in the unsaturated zone decreased due to restricted gas exchange with the atmosphere. As the soil thawed, O2 penetrated deeper into the soil enhancing the aerobic mineralization of organic carbon and nitrogen. Additionally, with the onset of thawing a pulse of gas <span class="hlt">flux</span> occurred, which is attributed to the build-up of respiratory gases in the pore space during freezing. The latter implies enhanced anaerobic respiration as O2 supply ceases when the upper soil layer freezes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930022364','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930022364"><span>Progress in the measurement of SSME turbine heat <span class="hlt">flux</span> with plug-type sensors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Liebert, Curt H.</p> <p>1991-01-01</p> <p>Data reduction was completed for tests of plug-type heat <span class="hlt">flux</span> sensors (gauges) in a turbine blade thermal <span class="hlt">cycling</span> tester (TBT) that is located at NASA/Marshall Space Flight Center, and a typical gauge is illustrated. This is the first time that heat <span class="hlt">flux</span> has been measured in a Space Shuttle Main Engine (SSME) Turbopump Turbine environment. The development of the concept for the gauge was performed in a heat <span class="hlt">flux</span> measurement facility at Lewis. In this facility, transient and steady state absorbed surface heat <span class="hlt">flux</span> information was obtained from transient temperature measurements taken at points within the gauge. A schematic of the TBT is presented, and plots of the absorbed surface heat <span class="hlt">flux</span> measured on the three blades tested in the TBT are presented. High quality heat <span class="hlt">flux</span> values were measured on all three blades. The experiments demonstrated that reliable and durable gauges can be repeatedly fabricated into the airfoils. The experiment heat <span class="hlt">flux</span> data are being used for verification of SSME analytical stress, boundary layer, and heat transfer design models. Other experimental results and future plans are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/14628061','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/14628061"><span>The long-term carbon <span class="hlt">cycle</span>, fossil fuels and atmospheric composition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Berner, Robert A</p> <p>2003-11-20</p> <p>The long-term carbon <span class="hlt">cycle</span> operates over millions of years and involves the exchange of carbon between rocks and the Earth's surface. There are many complex feedback pathways between carbon burial, nutrient <span class="hlt">cycling</span>, atmospheric carbon dioxide and oxygen, and climate. New calculations of carbon <span class="hlt">fluxes</span> during the Phanerozoic eon (the past 550 million years) illustrate how the long-term carbon <span class="hlt">cycle</span> has affected the burial of organic matter and fossil-fuel formation, as well as the evolution of atmospheric composition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19890001370','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19890001370"><span>Rotational modulation of hydrogen Lyman alpha <span class="hlt">flux</span> from 44ii Bootis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vilhu, O.; Neff, J. E.; Rahunen, T.</p> <p>1988-01-01</p> <p>Observations with IUE that cover the entire 6.4 hr orbital <span class="hlt">cycle</span> of the late-type contact binary 44i Bootis are presented. Intrinsic stellar hydrogen Lyman alpha emission <span class="hlt">flux</span> was determined from low-resolution IUE spectra, compensating for geocoronal emission and for interstellar absorption. The variation of the stellar Lyman alpha emission <span class="hlt">flux</span> correlates well with the variation of the C II and C IV emission <span class="hlt">fluxes</span>, and shows orbital modulation in phase with the visual light curve. The ratio of Lyman alpha to CII <span class="hlt">flux</span> (15 to 20) is similar to that observed in solar active regions. Hydrogen Lyman alpha emission is thus one of the most important cooling channels in the outer atmosphere of 44i Boo. A high-resolution spectrum of the Lyman alpha line was obtained between orbital phases 0.0 and 0.6. The integrated <span class="hlt">flux</span> in the observed high-resolution Lyman alpha profile is consistent with the <span class="hlt">fluxes</span> determined using low-resolution spectra, and the composite profile indicates that both components of this binary have equally active chromospheres and transition regions. The uncertainty in the interstellar hydrogen column density cannot mimic the observed variation in the integrated Lyman alpha <span class="hlt">flux</span>, because the stellar line is very much broader than the interstellar absorption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890039763&hterms=boo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dboo','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890039763&hterms=boo&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dboo"><span>Rotational modulation of hydrogen Lyman alpha <span class="hlt">flux</span> from 44i Bootis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Vilhu, O.; Neff, J. E.; Rahunen, T.</p> <p>1989-01-01</p> <p>Observations with IUE that cover the entire 6.4 hr orbital <span class="hlt">cycle</span> of the late-type contact binary 44i Bootis are presented. Intrinsic stellar hydrogen Lyman alpha emission <span class="hlt">flux</span> was determined from low-resolution IUE spectra, compensating for geocoronal emission and for interstellar absorption. The variation of the stellar Lyman alpha emission <span class="hlt">flux</span> correlates well with the variation of the CII and CIV emission <span class="hlt">fluxes</span>, and shows orbital modulation in phase with the visual light curve. The ratio of Lyman alpha to CII <span class="hlt">flux</span> (15 to 20) is similar to that observed in solar active regions. Hydrogen Lyman alpha emission is thus one of the most important cooling channels in the outer atmosphere of 44i Boo. A high-resolution spectrum of the Lyman alpha line was obtained between orbital phases 0.0 and 0.6. The integrated <span class="hlt">flux</span> in the observed high-resolution Lyman alpha profile is consistent with the <span class="hlt">fluxes</span> determined using low-resolution spectra, and the composite profile indicates that both components of this binary have equally active chromospheres and transition regions. The uncertainty in the interstellar hydrogen column density cannot mimic the observed variation in the integrated Lyman alpha <span class="hlt">flux</span>, because the stellar line is very much broader than the interstellar absorption.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343280','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5343280"><span>Alterations in Cytosolic and Mitochondrial [U-13C]Glucose Metabolism in a Chronic Epilepsy Mouse Model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Carrasco-Pozo, Catalina</p> <p>2017-01-01</p> <p>Abstract Temporal lobe epilepsy is a common form of adult epilepsy and shows high resistance to treatment. Increasing evidence has suggested that metabolic dysfunction contributes to the development of seizures, with previous studies indicating impairments in brain glucose metabolism. Here we aim to elucidate which pathways involved in glucose metabolism are impaired, by tracing the hippocampal metabolism of injected [U-13C]glucose (i.p.) during the chronic stage of the pilocarpine-status epilepticus mouse model of epilepsy. The enrichment of 13C in the intermediates of glycolysis and the <span class="hlt">TCA</span> <span class="hlt">cycle</span> were quantified in hippocampal extracts using liquid chromatography–tandem mass spectroscopy, along with the measurement of the activities of enzymes in each pathway. We show that there is reduced incorporation of 13C in the intermediates of glycolysis, with the percentage enrichment of all downstream intermediates being highly correlated with those of glucose 6-phosphate. Furthermore, the activities of all enzymes in this pathway including hexokinase and phosphofructokinase were unaltered, suggesting that glucose uptake is reduced in this model without further impairments in glycolysis itself. The key findings were 33% and 55% losses in the activities of pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase, respectively, along with reduced 13C enrichment in <span class="hlt">TCA</span> <span class="hlt">cycle</span> intermediates. This lower 13C enrichment is best explained in part by the reduced enrichment in glycolytic intermediates, whereas the reduction of key <span class="hlt">TCA</span> <span class="hlt">cycle</span> enzyme activity indicates that <span class="hlt">TCA</span> <span class="hlt">cycling</span> is also impaired in the hippocampal formation. Together, these data suggest that multitarget approaches may be necessary to restore metabolism in the epileptic brain. PMID:28303258</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19890058230&hterms=SME&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DSME','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19890058230&hterms=SME&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DSME"><span>A seven-month solar <span class="hlt">cycle</span> observed with the Langmuir probe on Pioneer Venus Orbiter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hoegy, W. R.; Wolff, C. L.</p> <p>1989-01-01</p> <p>Data collected by the Langmuir probe aboard the Pioneer Venus orbiter (PVO) over the years 1979 though 1987 were normalized to remove the long-period 11-year solar maximum to minimum trend and were analyzed for periodicity. Results yield evidence for the existence of an approximately 7-month solar <span class="hlt">cycle</span>, which was also observed from SME Lyman alpha and 2800-MHz radio <span class="hlt">flux</span> measurements carried out from an earth-based platform. This coincidence suggests that the <span class="hlt">cycle</span> is an intrinsic periodicity in the solar output. The <span class="hlt">cycle</span> has a frequency independent of the orbital frequency of the PVO and is distinct from a 'rotating beacon' <span class="hlt">cycle</span> whose period depends on the orbital motion of the PVO about the sun. The second most dominant <span class="hlt">cycle</span> discovered was a 5-month period. Results of an oscillation model of solar periodicity indicate that the 7-month and 5-month <span class="hlt">cycles</span> are caused by long-lived <span class="hlt">flux</span> enhancements from nonlinear interactions of global oscillation modes in the sun's convective envelope (r modes) and radiative interior (g modes).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A21I2289S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A21I2289S"><span>Variability of Kelvin wave momentum <span class="hlt">flux</span> from high-resolution radiosonde and radio occultation data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sjoberg, J. P.; Zeng, Z.; Ho, S. P.; Birner, T.; Anthes, R. A.; Johnson, R. H.</p> <p>2017-12-01</p> <p>Direct measurement of momentum <span class="hlt">flux</span> from Kelvin waves in the stratosphere remains challenging. Constraining this <span class="hlt">flux</span> from observations is an important step towards constraining the <span class="hlt">flux</span> from models. Here we present results from analyses using linear theory to estimate the Kelvin wave amplitudes and momentum <span class="hlt">fluxes</span> from both high-resolution radiosondes and from radio occultation (RO) data. These radiosonde data are from a contiguous 11-year span of soundings performed at two Department of Energy Atmospheric Radiation Measurement sites, while the RO data span 14 years from multiple satellite missions. Daily time series of the <span class="hlt">flux</span> from both sources are found to be in quantitative agreement with previous studies. Climatological analyses of these data reveal the expected seasonal <span class="hlt">cycle</span> and variability associated with the quasi-biennial oscillation. Though both data sets provide measurements on distinct spatial and temporal scales, the estimated <span class="hlt">flux</span> from each provides insight into separate but complimentary aspects of how the Kelvin waves affect the stratosphere. Namely, <span class="hlt">flux</span> derived from radiosonde sites provide details on the regional Kelvin wave variability, while the <span class="hlt">flux</span> from RO data are zonal mean estimates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMGC23K..11B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMGC23K..11B"><span>Inland Waters and the North American Carbon <span class="hlt">Cycle</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Butman, D. E.; Striegl, R. G.; Stackpoole, S. M.; del Giorgio, P.; Prairie, Y.; Pilcher, D.; Raymond, P. A.; Alcocer, J.; Paz, F.</p> <p>2016-12-01</p> <p>Inland aquatic ecosystems process, store, and release carbon to the atmosphere and coastal margins. The form of this carbon is a function of terrestrial and aquatic primary and secondary production, the weathering of materials in soils and subsurface environments, the hydrologic controls on the movement of carbon from land to inland waters, and the connectivity between streams, rivers, lakes, reservoirs and groundwater. The 2007 1st State of the Carbon <span class="hlt">Cycle</span> reported <span class="hlt">fluxes</span> for the continental United States (CONUS) only. Streams and rivers exported 30-40 Tg C yr-1 to coastal environments, and 17-25 Tg C yr-1 were buried in lake and reservoir sediments. Remarkably, the 2007 report did not quantify gas emissions, which represent over half of the total carbon <span class="hlt">fluxes</span> through inland water in the US. Current research has shown that 71-149 Tg C yr-1 exits freshwater systems either through atmospheric emissions of carbon dioxide or as inorganic and organic carbon <span class="hlt">fluxes</span> to the coast from the CONUS. These estimates did not include the Laurentian Great Lakes. Variation in the magnitude of these <span class="hlt">fluxes</span> across regions of the CONUS has been linked to differences in precipitation and terrestrial net ecosystem production. Similar comprehensive assessments have not been done for Canada or Mexico. Here we provide, as part of the 2nd State of the Carbon <span class="hlt">Cycle</span> report, estimates for the river coastal export and vertical emissions of carbon from inland waters of North America, and report major data gaps, and weaknesses in methodologies. These findings stress that strong international partnerships are needed to improve assessment, monitoring, and modeling of human impacts on the magnitude and timing of aquatic <span class="hlt">fluxes</span> in the future.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22663825-simulation-study-hemispheric-phase-asymmetry-solar-cycle','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22663825-simulation-study-hemispheric-phase-asymmetry-solar-cycle"><span>SIMULATION STUDY OF HEMISPHERIC PHASE-ASYMMETRY IN THE SOLAR <span class="hlt">CYCLE</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Shukuya, D.; Kusano, K., E-mail: kusano@nagoya-u.jp</p> <p>2017-01-20</p> <p>Observations of the Sun suggest that solar activities systematically create north–south hemispheric asymmetries. For instance, the hemisphere in which sunspot activity is more active tends to switch after the early half of each solar <span class="hlt">cycle</span>. Svalgaard and Kamide recently pointed out that the time gaps of polar field reversal between the northern and southern hemispheres are simply consequences of the asymmetry of sunspot activity. However, the mechanism underlying the asymmetric feature in solar <span class="hlt">cycle</span> activity is not yet well understood. In this paper, in order to explain the cause of the asymmetry from the theoretical point of view, we investigatemore » the relationship between the dipole- and quadrupole-type components of the magnetic field in the solar <span class="hlt">cycle</span> using the mean-field theory based on the <span class="hlt">flux</span> transport dynamo model. As a result, we found that there are two different attractors of the solar <span class="hlt">cycle</span>, in which either the north or the south polar field is first reversed, and that the <span class="hlt">flux</span> transport dynamo model explains well the phase-asymmetry of sunspot activity and the polar field reversal without any ad hoc source of asymmetry.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1198487-model-methane-cycle-permafrost-hydrology-siberian-continental-margin','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1198487-model-methane-cycle-permafrost-hydrology-siberian-continental-margin"><span>A model of the methane <span class="hlt">cycle</span>, permafrost, and hydrology of the Siberian continental margin</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Archer, D.</p> <p>2014-06-03</p> <p>A two-dimensional model of a passive continental margin was adapted to the simulation of the methane <span class="hlt">cycle</span> on Siberian continental shelf and slope, attempting to account for the impacts of glacial/interglacial <span class="hlt">cycles</span> in sea level, alternately exposing the continental shelf to freezing conditions with deep permafrost formation during glacial times, and immersion in the ocean in interglacial times. The model is used to gauge the impact of the glacial <span class="hlt">cycles</span>, and potential anthropogenic warming in the deep future, on the atmospheric methane emission <span class="hlt">flux</span>, and the sensitivities of that <span class="hlt">flux</span> to processes such as permafrost formation and terrestrial organic carbonmore » (Yedoma) deposition. Hydrological forcing drives a freshening and ventilation of pore waters in areas exposed to the atmosphere, which is not quickly reversed by invasion of seawater upon submergence, since there is no analogous saltwater pump. This hydrological pump changes the salinity enough to affect the stability of permafrost and methane hydrates on the shelf. Permafrost formation inhibits bubble transport through the sediment column, by construction in the model. The impact of permafrost on the methane budget is to replace the bubble <span class="hlt">flux</span> by offshore groundwater flow containing dissolved methane, rather than accumulating methane for catastrophic release when the permafrost seal fails during warming. By far the largest impact of the glacial/interglacial <span class="hlt">cycles</span> on the atmospheric methane <span class="hlt">flux</span> is attenuation by dissolution of bubbles in the ocean when sea level is high. Methane emissions are highest during the regression (soil freezing) part of the <span class="hlt">cycle</span>, rather than during transgression (thawing). The model-predicted methane <span class="hlt">flux</span> to the atmosphere in response to a warming climate is small, relative to the global methane production rate, because of the ongoing flooding of the continental shelf. A slight increase due to warming could be completely counteracted by sea level rise on geologic time</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012E%26PSL.317..396P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012E%26PSL.317..396P"><span>How large is the subducted water <span class="hlt">flux</span>? New constraints on mantle regassing rates</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parai, R.; Mukhopadhyay, S.</p> <p>2012-02-01</p> <p>Estimates of the subducted water (H2O) <span class="hlt">flux</span> have been used to discuss the regassing of the mantle over Earth history. However, these estimates vary widely, and some are large enough to have reduced the volume of water in the global ocean by a factor of two over the Phanerozoic. In light of uncertainties in the hydration state of subducting slabs, magma production rates and mantle source water contents, we use a Monte Carlo simulation to set limits on long-term global water <span class="hlt">cycling</span> and the return <span class="hlt">flux</span> of water to the deep Earth. Estimates of magma production rates and water contents in primary magmas generated at ocean islands, mid-ocean ridges, arcs and back-arcs are paired with estimates of water entering trenches via subducting oceanic slab in order to construct a model of the deep Earth water <span class="hlt">cycle</span>. The simulation is constrained by reconstructions of Phanerozoic sea level change, which suggest that ocean volume is near steady-state, though a sea level decrease of up to 360 m may be supported. We provide limits on the return <span class="hlt">flux</span> of water to the deep Earth over the Phanerozoic corresponding to a near steady-state exosphere (0-100 meter sea level decrease) and a maximum sea level decrease of 360 m. For the near steady-state exosphere, the return <span class="hlt">flux</span> is 1.4 - 2.0- 0.3+ 0.4 × 1013 mol/yr, corresponding to 2-3% serpentinization in 10 km of lithospheric mantle. The return <span class="hlt">flux</span> that generates the maximum sea level decrease over the Phanerozoic is 3.5- 0.3+ 0.4 × 1013 mol/yr, corresponding to 5% serpentinization in 10 km of lithospheric mantle. Our estimates of the return <span class="hlt">flux</span> of water to the mantle are up to 7 times lower than previously suggested. The imbalance between our estimates of the return <span class="hlt">flux</span> and mantle output <span class="hlt">flux</span> leads to a low rate of increase in bulk mantle water content of up to 24 ppm/Ga.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22364042-possible-chromospheric-activity-cycles-ad-leo','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22364042-possible-chromospheric-activity-cycles-ad-leo"><span>POSSIBLE CHROMOSPHERIC ACTIVITY <span class="hlt">CYCLES</span> IN AD LEO</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Buccino, Andrea P.; Petrucci, Romina; Mauas, Pablo J. D.</p> <p>2014-01-20</p> <p>AD Leo (GJ 388) is an active dM3 flare star that has been extensively observed both in the quiescent and flaring states. Since this active star is near the fully convective boundary, studying its long-term chromospheric activity in detail could be an appreciable contribution to dynamo theory. Here, using the Lomb-Scargle periodogram, we analyze the Ca II K line-core <span class="hlt">fluxes</span> derived from CASLEO spectra obtained between 2001 and 2013 and the V magnitude from the ASAS database between 2004 and 2010. From both of these totally independent time series, we obtain a possible activity <span class="hlt">cycle</span> with a period of approximately seven yearsmore » and a less significant shorter <span class="hlt">cycle</span> of approximately two years. A tentative interpretation is that a dynamo operating near the surface could be generating the longer <span class="hlt">cycle</span>, while a second dynamo operating in the deep convection zone could be responsible for the shorter one. Based on the long duration of our observing program at CASLEO and the fact that we observe different spectral features simultaneously, we also analyze the relation between simultaneous measurements of the Na I index (R{sub D}{sup ′}), Hα, and Ca II K <span class="hlt">fluxes</span> at different activity levels of AD Leo, including flares.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MNRAS.470..276S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MNRAS.470..276S"><span>Carrington <span class="hlt">cycle</span> 24: the solar chromospheric emission in a historical and stellar perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schröder, K.-P.; Mittag, M.; Schmitt, J. H. M. M.; Jack, D.; Hempelmann, A.; González-Pérez, J. N.</p> <p>2017-09-01</p> <p>We present the solar S-index record of <span class="hlt">cycle</span> 24, obtained by the Telescopio Internacional de Guanajuato, Robotico Espectroscopico robotic telescope facility and its high-resolution spectrograph HEROS (R ≈ 20 000), which measures the solar chromospheric Ca II H&K line emission by using moonlight. Our calibration process uses the same set of standard stars as introduced by the Mount Wilson team, thus giving us a direct comparison with their huge body of observations taken between 1966 and 1992, as well as with other cool stars. Carrington <span class="hlt">cycle</span> 24 activity started from the unusually deep and long minimum 2008/2009, with an S-index average of only 0.154, 0.015 deeper than the one of 1986 (〈S〉 = 0.169). In this respect, the chromospheric radiative losses differ remarkably from the variation of the coronal radio <span class="hlt">flux</span> F10.7 cm and the sunspot numbers. In addition, the <span class="hlt">cycle</span> 24 S-amplitude remained small, 0.022 (<span class="hlt">cycles</span> 21 and 22 averaged: 0.024), and so resulted in a very low 2014 maximum of 〈S〉 = 0.176 (<span class="hlt">cycles</span> 21 and 22 averaged: 0.193). We argue that this find is significant, since the Ca II H&K line emission is a good proxy for the solar far-ultraviolet (far-UV) <span class="hlt">flux</span>, which plays an important role in the heating of the Earth's stratosphere, and we further argue that the solar far-UV <span class="hlt">flux</span> changes with solar activity much more strongly than the total solar output.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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