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Sample records for methanogenesis primarily drive

  1. Sulfate reduction and methanogenesis in marine sediments

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Taylor, B. F.

    1978-01-01

    Methanogenesis and sulfate-reduction were followed in laboratory incubations of sediments taken from tropical seagrass beds. Methanogenesis and sulfate-reduction occurred simultaneously in sediments incubated under N2, thereby indicating that the two processes are not mutually exclusive. Sediments incubated under an atmosphere of H2 developed negative pressures due to the oxidation of H2 by sulfate-respiring bacteria. H2 also stimulated methanogenesis, but methanogenic bacteria could not compete for H2 with the sulfate-respiring bacteria.

  2. Evidence for Methanogenesis in ANME Archaea

    NASA Astrophysics Data System (ADS)

    Lloyd, K. G.; Kevorkian, R.

    2014-12-01

    Methanogenesis, unlike many higher energy-yielding metabolisms, can be exergonic in the reverse direction at reasonable concentrations of products and reactants. This is because the ΔGf for hydrogenotrophic methanogenesis, 4H2 + CO2 → CH4 + H2O, is quite low, and also because hydrogen exerts a fourth-power control on the reaction quotient. This means that common sedimentary metabolisms such as sulfate reduction and metal reduction can draw hydrogen concentrations low enough as a result of their metabolism to make reverse methanogenesis, or anaerobic methane oxidation, exergonic and potentially a useful energy source for life. Previous work has provided evidence for reverse methanogenesis in marine sediments, but an organism capable of both forward and reverse methanogenesis has not been identified. We present evidence in support of the theory that anaerobic methanotrophs (ANME), which are commonly found in methane producing environments, are capable of growth under methanogenic conditions in anoxic incubations of marine sediments from Cape Lookout Bight, NC. Coupled to a large body of literature studying the participation of ANME archaea in methanotrophy (as well as having molecular machinery for methanogenesis), we propose that these difficult-to-culture organisms can also perform methanogenesis when conditions dictate that methanogenesis is exergonic.

  3. Abiogenic methanogenesis in crystalline rocks

    SciTech Connect

    Lollar, B.S.; Frape, S.K. ); Weise, S.M. , Neuherberg ); Fritz, P. ); Macko, S.A. ); Welhan, J.A. )

    1993-12-01

    Isotopically anomalous CH[sub 4]-rich gas deposits are found in mining sites on both the Canadian and Fennoscandian shields. With [delta][sup 13]C[sub CH4] values from -22.4 to -48.5% and [delta]D[sub CH4] values from -133 to -372%, these methane deposits cannot be accounted for by conventional processes for bacterial or thermogenic methanogenesis. Compositionally the gases are similar to other CH[sub 4]-rich gas occurrences found in Canadian and Fennoscandian shield rocks. However, the isotopically anomalous gases of this study are characterized by unexpectedly high concentrations of H[sub 2] gas, ranging from several volume percent up to 30 vol%. The H[sub 2] gases are consistently depleted in the heavy isotope, with [delta]D[sub H[sub 2

  4. Laboratory support for a methanogenesis driven

    NASA Astrophysics Data System (ADS)

    Navarro-Gonzalez, R.; Montoya, L.; Davis, W.; McKay, C.

    Recent geological evidence strongly suggests that Europa may currently possess a global subsurface water ocean. Since liquid water is a fundamental requirement for life as we know it, there is great speculation on the possibility of life in Europa. For such organisms to survive, there must be an energy source available for metabolism, growth and reproduction. On Earth this energy is principally derived from sunlight through photosynthesis. Due to the expected large ice crust thickness (10 to 100 km) of the satellite, this energy source is unlikely to support a biosphere. Hydrothermal vents have been suggested as a potential environment for chemotrophs. However, for such organisms to obtain energy they depend on oxidants dissolved and transported from the oxygenic Earth's atmosphere to the deep ocean. Without a supply of oxidants from Europa's crust, methanogenesis associated to hydrothermal vents may potentially drive a biosphere in Europa's ocean. Here we explore this possibility experimentally by simulating a hydrothermal vent relevant to Europa and analyzing the resulting gas products by gas chromatography coupled to Fourier transform infrared and mass spectrometries. The chemical composition of the hydrothermal vent gases was derived from a thermochemical model assuming that Europa had a cometary (solar, less H) abundance at a high temperature characteristic of a vent. Specifically the following gas mixture was used: 45% CO2 , 45% CH4 and 10 % N2 . A 500 ml stainless steel reactor was filled with 200 ml triply distilled water and the gas mixture at 1 bar at 25 °C . In some experiments 3 g of pyrite were added into the reaction vessel. The system was heated for 24 hrs at 350 °C . At the completion of the experiment, the reaction was quenched to 25 °C and the gas mixture gas analyzed by GC-FTIR-MS techniques. In the absence of pyrite, methane is oxidized to carbon dioxide with the possible production of hydrogen. In contrast in the presence of pyrite, methane

  5. A New Era of Methanogenesis Research.

    PubMed

    Lever, Mark Alexander

    2016-02-01

    The reductive acetyl-CoA pathway coupled to methanogenesis is likely one of Earth's oldest metabolisms. Yet, until recently this metabolism had only been found in the kingdom Euryarchaeota. A study now suggests that distantly related Bathyarchaeota are also methanogens and that methane metabolism is more phylogenetically widespread than previously thought. PMID:26765541

  6. Microbiology of Methanogenesis in Thermal, Volcanic Environments

    PubMed Central

    Zeikus, J. G.; Ben-Bassat, Arie; Hegge, P. W.

    1980-01-01

    Microbial methanogenesis was examined in thermal waters, muds, and decomposing algal-bacterial mats associated with volcanic activity in Yellowstone National Park. Radioactive tracer studies with [14C]glucose, acetate, or carbonate and enrichment culture techniques demonstrated that methanogenesis occurred at temperatures near 70°C but below 80°C and correlated with hydrogen production from either geothermal processes or microbial fermentation. Three Methanobacterium thermoautotrophicum strains (YT1, YTA, and YTC) isolated from diverse volcanic habitats differed from the neotype sewage strain ΔH in deoxyribonucleic acid guanosine-plus-cytosine content and immunological properties. Microbial methanogenesis was characterized in more detail at a 65°C site in the Octopus Spring algal-bacterial mat ecosystem. Here methanogenesis was active, was associated with anaerobic microbial decomposition of biomass, occurred concomitantly with detectable microbial hydrogen formation, and displayed a temperature activity optimum near 65°C. Enumeration studies estimated more than 109 chemoorganotrophic hydrolytic bacteria and 106 chemolithotrophic methanogenic bacteria per g (dry weight) of algal-bacterial mat. Enumeration, enrichment, and isolation studies revealed that the microbial population was predominantly rod shaped and asporogenous. A prevalent chemoorganotrophic organism in the mat that was isolated from an end dilution tube was a taxonomically undescribed gram-negative obligate anaerobe (strain HTB2), whereas a prevalent chemolithotrophic methanogen isolated from an end dilution tube was identified as M. thermoautotrophicum (strain YTB). Taxonomically recognizable obligate anaerobes that were isolated from glucose and xylose enrichment cultures included Thermoanaerobium brockii strain HTB and Clostridium thermohydrosulfuricum strain 39E. The nutritional properties, growth temperature optima, growth rates, and fermentation products of thermophilic bacterial strains 39

  7. Methanogenesis and Methanotrophy in Serpentinizing Systems

    NASA Astrophysics Data System (ADS)

    Shock, E.; Poret-Peterson, A.; Canovas, P. A.; Robinson, K.; Marsala, P.

    2012-12-01

    Serpentinization leads to habitat generation, most obviously through the production of hydrogen and methane. These compounds, on the other hand, can be made by microbes and their production may be facilitated by conditions generated through serpentinization. The Samail ophiolite in northern Oman, hosts a number of hyperalkaline springs (pH>10) with fluids enriched in methane and hydrogen and severely depleted in dissolved inorganic carbon (DIC), relative to neighboring surface waters. Reaction path modeling of mixing between surface water and serpentinizing fluids, using data from our recent field work in Oman, shows that methanogenesis is promoted when small inputs of surface water (up to 20% of the total mixture) contribute DIC, and that methanotrophy is promoted by higher mixing ratios of surface water to serpentinizing fluids owing to the increasing abundance of dissolved oxygen. Whether methane and hydrogen originate from abiotic serpentinization, microbial metabolism, or a combination of biotic and abiotic processes in these springs remains an open question, which can be addressed in part through analysis of genes for methane and hydrogen metabolism. We amplified genes for methanogenesis (methyl coenzyme M reductase; mcrA), hydrogen metabolism (hydrogenase; hydA), and aerobic methane oxidation (particulate methane monooxygenase; pmoA) from hyperalkaline spring sediments. The genes we retrieved are most similar to sequences already obtained from deep subsurface (mcrA) or alkaline (hydA and pmoA) environments. Biological methanogenesis in hyperalkaline spring sediments is likely mediated by hydrogenotrophic methanogens based on the affiliation of the mcrA genes, and consistent with our reaction path modeling. Hydrogenase genes were most closely related to sequences from cultured organisms belonging to the orders Clostridiales and Bacteroidales and the class Deltaproteobacteria. Aerobic methane oxidation is likely mediated by alphaproteobacterial methanotrophs

  8. Substrate limitation for methanogenesis in hypersaline environments.

    PubMed

    Kelley, Cheryl A; Poole, Jennifer A; Tazaz, Amanda M; Chanton, Jeffrey P; Bebout, Brad M

    2012-02-01

    Motivated by the increasingly abundant evidence for hypersaline environments on Mars and reports of methane in its atmosphere, we examined methanogenesis in hypersaline ponds in Baja California Sur, Mexico, and in northern California, USA. Methane-rich bubbles trapped within or below gypsum/halite crusts have δ¹³C values near -40‰. Methane with these relatively high isotopic values would typically be considered thermogenic; however, incubations of crust samples resulted in the biological production of methane with similar isotopic composition. A series of measurements aimed at understanding the isotopic composition of methane in hypersaline systems was therefore undertaken. Methane production rates, as well as the concentrations and isotopic composition of the particulate organic carbon (POC), were measured. Methane production was highest from microbial communities living within gypsum crusts, whereas POC content at gypsum/halite sites was low, generally less than 1% of the total mass. The isotopic composition of the POC ranged from -26‰ to -10‰. To determine the substrates used by the methanogens, ¹³C-labeled methylamines, methanol, acetate, and bicarbonate were added to individual incubation vials, and the methane produced was monitored for ¹³C content. The main substrates used by the methanogens were the noncompetitive substrates, the methylamines, and methanol. When unlabeled trimethylamine (TMA) was added to incubating gypsum/halite crusts in increasing concentrations, the isotopic composition of the methane produced became progressively lower; the lowest methane δ¹³C values occurred when the most TMA was added (1000 μM final concentration). This decrease in the isotopic composition of the methane produced with increasing TMA concentrations, along with the high in situ methane δ¹³C values, suggests that the methanogens within the crusts are operating at low substrate concentrations. It appears that substrate limitation is decreasing

  9. Biogeochemical metabolic modeling of methanogenesis by Methanosarcina barkeri

    NASA Astrophysics Data System (ADS)

    Jensvold, Z. D.; Jin, Q.

    2015-12-01

    Methanogenesis, the biological process of methane production, is the final step of natural organic matter degradation. In studying natural methanogenesis, important questions include how fast methanogenesis proceeds and how methanogens adapt to the environment. To address these questions, we propose a new approach - biogeochemical reaction modeling - by simulating the metabolic networks of methanogens. Biogeochemical reaction modeling combines geochemical reaction modeling and genome-scale metabolic modeling. Geochemical reaction modeling focuses on the speciation of electron donors and acceptors in the environment, and therefore the energy available to methanogens. Genome-scale metabolic modeling predicts microbial rates and metabolic strategies. Specifically, this approach describes methanogenesis using an enzyme network model, and computes enzyme rates by accounting for both the kinetics and thermodynamics. The network model is simulated numerically to predict enzyme abundances and rates of methanogen metabolism. We applied this new approach to Methanosarcina barkeri strain fusaro, a model methanogen that makes methane by reducing carbon dioxide and oxidizing dihydrogen. The simulation results match well with the results of previous laboratory experiments, including the magnitude of proton motive force and the kinetic parameters of Methanosarcina barkeri. The results also predict that in natural environments, the configuration of methanogenesis network, including the concentrations of enzymes and metabolites, differs significantly from that under laboratory settings.

  10. Methanogenesis from Sucrose by Defined Immobilized Consortia

    PubMed Central

    Jones, W. Jack; Guyot, Jean-Pierre; Wolfe, Ralph S.

    1984-01-01

    A bacterial consortium capable of sucrose degradation primarily to CH4 and CO2 was constructed, with acetate as the key methanogenic precursor. In addition, the effect of agar immobilization on the activity of the consortium was determined. The primary fermentative organism, Escherichia coli, produced acetate, formate, H2, and CO2 (known substrates for methanogens), as well as ethanol and lactate, compounds that are not substrates for methanogens. Oxidation of the nonmethanogenic substrates, lactate and ethanol, to acetate was mediated by the addition of Acetobacterium woodii and Desulfovibrio vulgaris. The methanogenic stage was accomplished by the addition of the acetophilic methanogen Methanosarcina barkeri and the hydrogenophilic methanogen Methanobacterium formicicum. Results of studies with low substrate concentrations (0.05 to 0.2% [wt/vol]), a growth-limiting medium, and the five-component consortium indicated efficient conversion (40%) of sucrose carbon to CH4. Significant decreases in yields of CH4 and rates of CH4 production were observed if any component of the consortium was omitted. Approximately 70% of the CH4 generated occurred via acetate. Agar-immobilized cells of the consortium exhibited yields of CH4 and rates of CH4 production from sucrose similar to those of nonimmobilized cells. The rate of CH4 production decreased by 25% when cysteine was omitted from reaction conditions and by 40% when the immobilized consortium was stored for 1 week at 4°C. PMID:16346452

  11. Methanogenesis from sucrose by defined immobilized consortia.

    PubMed

    Jones, W J; Guyot, J P; Wolfe, R S

    1984-01-01

    A bacterial consortium capable of sucrose degradation primarily to CH(4) and CO(2) was constructed, with acetate as the key methanogenic precursor. In addition, the effect of agar immobilization on the activity of the consortium was determined. The primary fermentative organism, Escherichia coli, produced acetate, formate, H(2), and CO(2) (known substrates for methanogens), as well as ethanol and lactate, compounds that are not substrates for methanogens. Oxidation of the nonmethanogenic substrates, lactate and ethanol, to acetate was mediated by the addition of Acetobacterium woodii and Desulfovibrio vulgaris. The methanogenic stage was accomplished by the addition of the acetophilic methanogen Methanosarcina barkeri and the hydrogenophilic methanogen Methanobacterium formicicum. Results of studies with low substrate concentrations (0.05 to 0.2% [wt/vol]), a growth-limiting medium, and the five-component consortium indicated efficient conversion (40%) of sucrose carbon to CH(4). Significant decreases in yields of CH(4) and rates of CH(4) production were observed if any component of the consortium was omitted. Approximately 70% of the CH(4) generated occurred via acetate. Agar-immobilized cells of the consortium exhibited yields of CH(4) and rates of CH(4) production from sucrose similar to those of nonimmobilized cells. The rate of CH(4) production decreased by 25% when cysteine was omitted from reaction conditions and by 40% when the immobilized consortium was stored for 1 week at 4 degrees C. PMID:16346452

  12. Conductive iron oxides accelerate thermophilic methanogenesis from acetate and propionate.

    PubMed

    Yamada, Chihaya; Kato, Souichiro; Ueno, Yoshiyuki; Ishii, Masaharu; Igarashi, Yasuo

    2015-06-01

    Anaerobic digester is one of the attractive technologies for treatment of organic wastes and wastewater, while continuous development and improvements on their stable operation with efficient organic removal are required. Particles of conductive iron oxides (e.g., magnetite) are known to facilitate microbial interspecies electron transfer (termed as electric syntrophy). Electric syntrophy has been reported to enhance methanogenic degradation of organic acids by mesophilic communities in soil and anaerobic digester. Here we investigated the effects of supplementation of conductive iron oxides (magnetite) on thermophilic methanogenic microbial communities derived from a thermophilic anaerobic digester. Supplementation of magnetite accelerated methanogenesis from acetate and propionate under thermophilic conditions, while supplementation of ferrihydrite also accelerated methanogenesis from propionate. Microbial community analysis revealed that supplementation of magnetite drastically changed bacterial populations in the methanogenic acetate-degrading cultures, in which Tepidoanaerobacter sp. and Coprothermobacter sp. dominated. These results suggest that supplementation of magnetite induce electric syntrophy between organic acid-oxidizing bacteria and methanogenic archaea and accelerate methanogenesis even under thermophilic conditions. Findings from this study would provide a possibility for the achievement of stably operating thermophilic anaerobic digestion systems with high efficiency for removal of organics and generation of CH4. PMID:25488041

  13. Methanogenesis from wastewater stimulated by addition of elemental manganese

    PubMed Central

    Qiao, Sen; Tian, Tian; Qi, Benyu; Zhou, Jiti

    2015-01-01

    This study presents a novel procedure for accelerating methanogenesis from wastewater by adding elemental manganese into the anaerobic digestion system. The results indicated that elemental manganese effectively enhanced both the methane yield and the production rate. Compared to the control test without elemental manganese, the total methane yield and production rate with 4 g/L manganese addition increased 3.4-fold (from 0.89 ± 0.03 to 2.99 ± 0.37 M/gVSS within 120 h) and 4.4-fold (from 6.2 ± 0.1 to 27.2 ± 2.2 mM/gVSS/h), respectively. Besides, more acetate consumption and less propionate generation were observed during the methanogenesis with manganese. Further studies demonstrated that the elemental manganese served as electron donors for the methanogenesis from carbon dioxide, and the final proportion of methane in the total generated gas with 4 g/L manganese addition reached 96.9%, which was 2.1-fold than that of the control (46.6%). PMID:26244609

  14. Primarily nonlinear effects observed in a driven asymmetrical vibrating wire

    NASA Astrophysics Data System (ADS)

    Hanson, Roger J.; Macomber, H. Kent; Morrison, Andrew C.; Boucher, Matthew A.

    2005-01-01

    The purpose of the work reported here is to further experimentally explore the wide variety of behaviors exhibited by driven vibrating wires, primarily in the nonlinear regime. When the wire is driven near a resonant frequency, it is found that most such behaviors are significantly affected by the splitting of the resonant frequency and by the existence of a ``characteristic'' axis associated with each split frequency. It is shown that frequency splitting decreases with increasing wire tension and can be altered by twisting. Two methods are described for determining the orientation of characteristic axes. Evidence is provided, with a possible explanation, that each axis has the same orientation everywhere along the wire. Frequency response data exhibiting nonlinear generation of transverse motion perpendicular to the driving direction, hysteresis, linear generation of perpendicular motion (sometimes tubular), and generation of motion at harmonics of the driving frequency are exhibited and discussed. Also reported under seemingly unchanging conditions are abrupt large changes in the harmonic content of the motion that sometimes involve large subharmonics and harmonics thereof. Slow transitions from one stable state of vibration to another and quasiperiodic motions are also exhibited. Possible musical significance is discussed. .

  15. Feasibility and benefits of methanogenesis under oxygen-limited conditions

    SciTech Connect

    Zitomer, D.H.; Shrout, J.D.

    1998-12-31

    Methanogenic and aerobic (or microaerophilic) biological processes are often considered mutually exclusive and separated as biological wastewater treatment options. However, under oxygen-limited conditions, both aerobic respiration and methanogenesis can be practically accomplished by a single mixed culture. This paper describes sustained batch culture, oxygen-limited methanogenic serum bottle and bench-scale systems. Serum bottle cultures exhibited methanogenic activity similar to or greater than that of a strictly anaerobic culture maintained in parallel. The COD removal efficiencies of anaerobic, oxygen-limited, and aerobic bench-scale reactors receiving 30,000 mg/l of sucrose were all greater than 93%, a system receiving 1 g O{sub 2}/L{sub R}-day achieved a lower final effluent COD than the strictly anaerobic reactor. After a shock-load of sucrose, the pH recovered in low-aeration batch reactors in 28--34 days, whereas anaerobic pH did not recover after 52 days of observation. In the future, methanogenesis under limited-aeration may be employed as an energy efficient treatment option to achieve low final COD concentrations, minimal biosolids generation, and mineralization of a broad range of specific organic chemicals.

  16. Numerical Modeling of Methanogenesis at Walker Ridge, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Glosser, D.; Cook, A.; Malinverno, A.; Daigle, H.

    2014-12-01

    Methane migration is a crucial link between locations of methane generation and natural gas hydrate reservoirs, yet migration mechanisms are poorly understood in the natural environment. In this study, we evaluate constraints on methanogenesis and methane diffusion through the development of a 1-dimensional diagenetic model of the Gulf of Mexico Gas Hydrate Joint Industry Project Site Walker Ridge 313 in the Gulf of Mexico. High saturation gas hydrate was confirmed at Walker Ridge from borehole logs, which measured both high compressional velocity and high resistivity in hydrate-bearing sand layers. Gas hydrate formation depends largely on organic matter concentration and methanogenesis rates. We will test how much organic matter is required to achieve gas hydrate saturations observed at Walker Ridge. Our model will incorporate methane generation around a sand layer as it is moves down through the sediment column. Variable porosity across the sediment column due to early diagenesis and sediment compaction will also be considered. Since methane solubility is higher in finer grained sediments due to smaller pore spaces, gas hydrate will form in the sand layer from methane transported by the relatively slow process of diffusion from finer grained layers. The results of this model are critical to the development of the basin scale simulation of overall methane flux based on the geometry of WR313. The simulation results will improve scientific characterization of how hydrates form and distribute within continental margin sediments.

  17. Bacterial methanogenesis in holocene sediments in the Baltic Sea

    SciTech Connect

    Lein, A.Y.; Namsaraev, B.B.; Trotsyuk, V.Y.; Ivanov, M.V.

    1981-01-01

    Soviet biologists have found evidence of viable methanogenic microorganisms in mud samples collected in 1978 from the Baltic Sea by the research ship Academician Kurchatov. Experiments with radioactive carbon and direct measurements of the samples' methane concentrations led to several conclusions: (1) the process of bacterial methanogenesis occurs mainly via carbon dioxide reduction, (2) the methanogenic intensity depends on the depth of the deposited sediment and its distance from land; shallow-water sediments found in gulfs produced more methane than deepwater ones taken from low spots, (3) organic-matter consumption during bacterial methane reduction makes up 0.14-7.9 mg of carbon/kg of wet mud per year; this is over 20 times less than during bacterial sulfate reduction, (4) The bulk of the methane generated migrates from the muds into the water and (5) marine sediments are undersaturated with methane, suggesting that the methane migrates via filtration of pore waters, not by diffusion.

  18. Methanogenesis in hypersaline environments -Analogs for Ancient Mars?

    NASA Astrophysics Data System (ADS)

    Bebout, Brad; Chanton, Jeff; Kelley, Cheryl; Tazaz, Amanda; Poole, Jennifer; García Maldonado, José Q.; López Cortés, Alejandro

    values, (ca. -60 to -30 o/oo). The hydrogen isotopic (δ 2 H) composition of the methane ranged from -450 to -350 o/oo. These combinations of carbon and hydrogen isotopic values include many outside of the range of values normally considered to be biogenic. Incubations of evaporitic minerals and sediments confirm, however, that the methane is indeed being produced within these sediments. Substrate limitation of methanogenesis in these environments, and not methane oxidation, can explain the isotopic values of the methane in these environments. Incubations with both isotopically labeled and unlabeled putative substrates for methanogenesis have shown that the substrates most important for methanogenesis in these environments are the so-called non competitive substrates, e.g., methylamines, dimethylsulfide, and methanol. Acetate and bicarbonate appear not to be important substrates for methanogens in these environments. Analysis of partial sequences of the methyl-CoM-reductase A gene (mcrA), involved in methane production, has revealed that the community composition of methanogens is consistent with organisms known to use non-competitive substrates. Our work has shown that hypersaline environments have the potential to both produce and preserve methane for analysis on other planets, e.g., by capable rovers on Mars. These studies expand the range of isotopic values now known to be produced by active methanogenesis, and offer explanations as to how methane with these particular stable isotopic values is produced.

  19. Characterization of an Archaeal Two-Component System That Regulates Methanogenesis in Methanosaeta harundinacea

    PubMed Central

    Guo, Xiaopeng; Qi, Lei; Dong, Xiuzhu

    2014-01-01

    Two-component signal transduction systems (TCSs) are a major mechanism used by bacteria in response to environmental changes. Although many sequenced archaeal genomes encode TCSs, they remain poorly understood. Previously, we reported that a methanogenic archaeon, Methanosaeta harundinacea, encodes FilI, which synthesizes carboxyl-acyl homoserine lactones, to regulate transitions of cellular morphology and carbon metabolic fluxes. Here, we report that filI, the cotranscribed filR2, and the adjacent filR1 constitute an archaeal TCS. FilI possesses a cytoplasmic kinase domain (histidine kinase A and histidine kinase-like ATPase) and its cognate response regulator. FilR1 carries a receiver (REC) domain coupled with an ArsR-related domain with potential DNA-binding ability, while FilR2 carries only a REC domain. In a phosphorelay assay, FilI was autophosphorylated and specifically transferred the phosphoryl group to FilR1 and FilR2, confirming that the three formed a cognate TCS. Through chromatin immunoprecipitation–quantitative polymerase chain reaction (ChIP-qPCR) using an anti-FilR1 antibody, FilR1 was shown to form in vivo associations with its own promoter and the promoter of the filI-filR2 operon, demonstrating a regulatory pattern common among TCSs. ChIP-qPCR also detected FilR1 associations with key genes involved in acetoclastic methanogenesis, acs4 and acs1. Electrophoretic mobility shift assays confirmed the in vitro tight binding of FilR1 to its own promoter and those of filI-filR2, acs4, and mtrABC. This also proves the DNA-binding ability of the ArsR-related domain, which is found primarily in Archaea. The archaeal promoters of acs4, filI, acs1, and mtrABC also initiated FilR1-modulated expression in an Escherichia coli lux reporter system, suggesting that FilR1 can up-regulate both archaeal and bacterial transcription. In conclusion, this work identifies an archaeal FilI/FilRs TCS that regulates the methanogenesis of M. harundinacea. PMID:24748383

  20. Methanogenesis and sulfate reduction: Competitive and noncompetitive substrates in estuarine sediments

    USGS Publications Warehouse

    Oremland, Ronald S.; Polcin, Sandra

    1982-01-01

    Sulfate ions did not inhibit methanogenesis in estuarine sediments supplemented with methanol, trimethylamine, or methionine. However, sulfate greatly retarded methanogenesis when hydrogen or acetate was the substrate. Sulfate reduction was stimulated by acetate, hydrogen, and acetate plus hydrogen, but not by methanol or trimethylamine. These results indicate that sulfate-reducing bacteria will outcompete methanogens for hydrogen, acetate, or both, but will not compete with methanogens for compounds like methanol, trimethylamine, or methionine, thereby allowing methanogenesis and sulfate reduction to operate simultaneously within anoxic, sulfate-containing sediments.

  1. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: I. KINETIC STUDIES AND EXPERIMENTS

    EPA Science Inventory

    Six anaerobic chemostats containing mixed microbial cultures were used to investigate the interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol and formic acid. Sulfate reducers outcompeted methanogens in acetate-fed chemostats whil...

  2. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: A FUNDAMENTAL EXPERIMENTAL KINETIC STUDY AND MODELING

    EPA Science Inventory

    Six chemostats containing mixed anaerobic cultures were used to investigate interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol, and formic acid. ulfate reducers outcompeted methanogens for acetic acid while methanol was not utili...

  3. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: I. KINETIC STUDIES AND EXPERIMENTS

    EPA Science Inventory

    Six anaerobic chemostats containing mixed microbial cultures were used to investigate the interactions between sulfate reduction and methanogenesis for three substrates: acetic acid, methanol, and formic acid. ulfate reducers outcompeted methanogens in acetate-fed chemostats whil...

  4. Impact of formation water geochemistry and crude oil biodegradation on microbial methanogenesis

    USGS Publications Warehouse

    Shelton, Jenna L.; McIntosh, Jennifer C.; Warwick, Peter D.; McCray, John E.

    2016-01-01

    Shallow wells (393–442 m depth) contained highly biodegraded oils associated with low extent of methanogenesis, while the deepest (> 1208 m) wells contained minimally degraded oils and produced fluids suggesting a low extent of methanogenesis. Mid-depth wells (666–857 m) in the central field had the highest indicators of methanogenesis and contained moderately biodegraded oils. Little correlation existed between extents of crude oil biodegradation and methanogenesis across the whole transect (avg.R2 = 0.13). However, when wells with the greatest extent of crude oil biodegradation were eliminated (3 of 6 oilfields), better correlation between extent of methanogenesis and biodegradation (avg. R2 = 0.53) was observed. The results suggest that oil quality and salinity impact methanogenic crude oil biodegradation. Reservoirs indicating moderate extent of crude oil biodegradation and high extent of methanogenesis, such as the central field, would be good candidates for attempting to enhance methanogenic crude oil biodegradation as a result of the observations from the study.

  5. Alamethicin suppresses methanogenesis and promotes acetogenesis in bioelectrochemical systems.

    PubMed

    Zhu, Xiuping; Siegert, Michael; Yates, Matthew D; Logan, Bruce E

    2015-06-01

    Microbial electrosynthesis (MES) systems with mixed cultures often generate a variety of gaseous and soluble chemicals. Methane is the primary end product in mixed-culture MES because it is the thermodynamically most favorable reduction product of CO2. Here, we show that the peptaibol alamethicin selectively suppressed the growth of methanogens in mixed-culture MES systems, resulting in a shift of the solution and cathode communities to an acetate-producing system dominated by Sporomusa, a known acetogenic genus in MES systems. Archaea in the methane-producing control were dominated by Methanobrevibacter species, but no Archaea were detected in the alamethicin-treated reactors. No methane was detected in the mixed-culture reactors treated with alamethicin over 10 cycles (∼ 3 days each). Instead, acetate was produced at an average rate of 115 nmol ml(-1) day(-1), similar to the rate reported previously for pure cultures of Sporomusa ovata on biocathodes. Mixed-culture control reactors without alamethicin generated methane at nearly 100% coulombic recovery, and no acetate was detected. These results show that alamethicin is effective for the suppression of methanogen growth in MES systems and that its use enables the production of industrially relevant organic compounds by the inhibition of methanogenesis. PMID:25819972

  6. Alamethicin Suppresses Methanogenesis and Promotes Acetogenesis in Bioelectrochemical Systems

    PubMed Central

    Zhu, Xiuping; Siegert, Michael; Yates, Matthew D.

    2015-01-01

    Microbial electrosynthesis (MES) systems with mixed cultures often generate a variety of gaseous and soluble chemicals. Methane is the primary end product in mixed-culture MES because it is the thermodynamically most favorable reduction product of CO2. Here, we show that the peptaibol alamethicin selectively suppressed the growth of methanogens in mixed-culture MES systems, resulting in a shift of the solution and cathode communities to an acetate-producing system dominated by Sporomusa, a known acetogenic genus in MES systems. Archaea in the methane-producing control were dominated by Methanobrevibacter species, but no Archaea were detected in the alamethicin-treated reactors. No methane was detected in the mixed-culture reactors treated with alamethicin over 10 cycles (∼3 days each). Instead, acetate was produced at an average rate of 115 nmol ml−1 day−1, similar to the rate reported previously for pure cultures of Sporomusa ovata on biocathodes. Mixed-culture control reactors without alamethicin generated methane at nearly 100% coulombic recovery, and no acetate was detected. These results show that alamethicin is effective for the suppression of methanogen growth in MES systems and that its use enables the production of industrially relevant organic compounds by the inhibition of methanogenesis. PMID:25819972

  7. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 45 Public Welfare 3 2011-10-01 2011-10-01 false Awards not primarily for research. 650.6 Section... PATENTS § 650.6 Awards not primarily for research. (a) Awards not primarily intended to support scientific or engineering research need contain no patent provision. Examples of such awards are travel...

  8. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 45 Public Welfare 3 2010-10-01 2010-10-01 false Awards not primarily for research. 650.6 Section... PATENTS § 650.6 Awards not primarily for research. (a) Awards not primarily intended to support scientific or engineering research need contain no patent provision. Examples of such awards are travel...

  9. Solute concentrations influence microbial methanogenesis in coal-bearing strata of the Cherokee basin, USA

    DOE PAGESBeta

    Kirk, Matthew F.; Wilson, Brien H.; Marquart, Kyle A.; Zeglin, Lydia H.; Vinson, David S.; Flynn, Theodore M.

    2015-11-18

    In this study, microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4–1.1 m) coalbeds with marginal thermal maturities (0.5–0.7% Ro) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na–Cl typemore » with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L–1. Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location

  10. Solute Concentrations Influence Microbial Methanogenesis in Coal-bearing Strata of the Cherokee Basin, USA.

    PubMed

    Kirk, Matthew F; Wilson, Brien H; Marquart, Kyle A; Zeglin, Lydia H; Vinson, David S; Flynn, Theodore M

    2015-01-01

    Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4-1.1 m) coalbeds with marginal thermal maturities (0.5-0.7% R o ) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na-Cl type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L(-1). Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content

  11. Solute Concentrations Influence Microbial Methanogenesis in Coal-bearing Strata of the Cherokee Basin, USA

    PubMed Central

    Kirk, Matthew F.; Wilson, Brien H.; Marquart, Kyle A.; Zeglin, Lydia H.; Vinson, David S.; Flynn, Theodore M.

    2015-01-01

    Microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4–1.1 m) coalbeds with marginal thermal maturities (0.5–0.7% Ro) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na–Cl type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L−1. Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast, bacterial diversity more strongly correlates with location than solute content

  12. Shifts in metabolic hydrogen sinks in the methanogenesis-inhibited ruminal fermentation: a meta-analysis

    PubMed Central

    Ungerfeld, Emilio M.

    2015-01-01

    Maximizing the flow of metabolic hydrogen ([H]) in the rumen away from CH4 and toward volatile fatty acids (VFA) would increase the efficiency of ruminant production and decrease its environmental impact. The objectives of this meta-analysis were: (i) To quantify shifts in metabolic hydrogen sinks when inhibiting ruminal methanogenesis in vitro; and (ii) To understand the variation in shifts of metabolic hydrogen sinks among experiments and between batch and continuous cultures systems when methanogenesis is inhibited. Batch (28 experiments, N = 193) and continuous (16 experiments, N = 79) culture databases of experiments with at least 50% inhibition in CH4 production were compiled. Inhibiting methanogenesis generally resulted in less fermentation and digestion in most batch culture, but not in most continuous culture, experiments. Inhibiting CH4 production in batch cultures resulted in redirection of metabolic hydrogen toward propionate and H2 but not butyrate. In continuous cultures, there was no overall metabolic hydrogen redirection toward propionate or butyrate, and H2 as a proportion of metabolic hydrogen spared from CH4 production was numerically smaller compared to batch cultures. Dihydrogen accumulation was affected by type of substrate and methanogenesis inhibitor, with highly fermentable substrates resulting in greater redirection of metabolic hydrogen toward H2 when inhibiting methanogenesis, and some oils causing small or no H2 accumulation. In both batch and continuous culture, there was a decrease in metabolic hydrogen recovered as the sum of propionate, butyrate, CH4 and H2 when inhibiting methanogenesis, and it is speculated that as CH4 production decreases metabolic hydrogen could be increasingly incorporated into formate, microbial biomass, and perhaps, reductive acetogenesis in continuous cultures. Energetic benefits of inhibiting methanogenesis depended on the inhibitor and its concentration and on the in vitro system. PMID:25699029

  13. Methanogenesis and CO 2 exchange in an ombrotrophic peat bog

    NASA Astrophysics Data System (ADS)

    Lloyd, David; Thomas, Katie L.; Benstead, Julie; Davies, Kevin L.; Lloyd, Siôn H.; Arah, Jonathan R. M.; Stephen, Karl D.

    Methanogenesis was studied in water-saturated peat cores from hollows in Ellergower Moss, New Galloway, Scotland. The concentration of CH 4, increased with depth from 0.8 μM at the surface to reach a plateau of 500 μM at 14 cm; at this depth CO 2 concentrations often reached 10 fold those of CH 4. O 2 decreased from near air saturation to less than 10 nM at 6 cm depth. Argon transport from the top of the core downwards occurred more rapidly (D=0.8-7×10 -8 m 2 s -1, dependent on depth) than could be accounted for by simple diffusion through the peat. Vascular plants ( Molinia, Eriophorum and Carex) had well-developed roots and were adapted to water-logged conditions in that they possessed extensive aerenchymatous lacunae throughout their roots, shoots and leaves. As well as facilitating O 2 diffusion downwards to submerged tissues, this system enables rapid diffusion upwards of CH 4. This process of gaseous transport in vascular plants is subject to control by stomata. Emission rates of CO 2 and CH 4 thus show diurnal rhythms at constant temperature. Free-run of CO 2 oscillation in the dark at 15 cm depth indicates circadian clock control. The temperature sensitivity of CH 4 emission is remarkably high ( Q10=3.0 between 10 and 20°C in the dark); in cores kept under natural conditions of temperature and daylight the daily rhythms entrain to the peat temperature cycles.

  14. Effect of ferrihydrite biomineralization on methanogenesis in an anaerobic incubation from paddy soil

    NASA Astrophysics Data System (ADS)

    Zhuang, Li; Xu, Jielong; Tang, Jia; Zhou, Shungui

    2015-05-01

    Microbial reduction of Fe(III) can be one of the major factors controlling methane production from anaerobic sedimentary environments, such as paddy soils and wetlands. Although secondary iron mineralization following Fe(III) reduction is a process that occurs naturally over time, it has not yet been considered in methanogenic systems. This study performed a long-term anaerobic incubation of a paddy soil and ferrihydrite-supplemented soil cultures to investigate methanogenesis during ferrihydrite biomineralization. The results revealed that the long-term effect of ferrihydrite on methanogenesis may be enhancement rather than suppression documented in previous studies. During initial microbial ferrihydrite reduction, methanogenesis was suppressed; however, the secondary minerals of magnetite formation was simultaneous with facilitated methanogenesis in terms of average methane production rate and acetate utilization rate. In the phase of magnetite formation, microbial community analysis revealed a strong stimulation of the bacterial Geobacter, Bacillus, and Sedimentibacter and the archaeal Methanosarcina in the ferrihydrite-supplemented cultures. Direct electric syntrophy between Geobacter and Methanosarcina via conductive magnetite is the plausible mechanism for methanogenesis acceleration along with magnetite formation. Our data suggested that a change in iron mineralogy might affect the conversion of anaerobic organic matter to methane and might provide a fresh perspective on the mitigation of methane emissions from paddy soils by ferric iron fertilization.

  15. Nitrite reduction and methanogenesis in a single-stage UASB reactor.

    PubMed

    Borges, L I; López-Vazquez, C M; García, H; van Lier, J B

    2015-01-01

    In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO(2)(-)-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO(2)(-)-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO(2)(-)-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO(2)(-) reduction to N₂. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater. PMID:26676012

  16. Essential anaplerotic role for the energy-converting hydrogenase Eha in hydrogenotrophic methanogenesis

    PubMed Central

    Lie, Thomas J.; Costa, Kyle C.; Lupa, Boguslaw; Korpole, Suresh; Whitman, William B.; Leigh, John A.

    2012-01-01

    Despite decades of study, electron flow and energy conservation in methanogenic Archaea are still not thoroughly understood. For methanogens without cytochromes, flavin-based electron bifurcation has been proposed as an essential energy-conserving mechanism that couples exergonic and endergonic reactions of methanogenesis. However, an alternative hypothesis posits that the energy-converting hydrogenase Eha provides a chemiosmosis-driven electron input to the endergonic reaction. In vivo evidence for both hypotheses is incomplete. By genetically eliminating all nonessential pathways of H2 metabolism in the model methanogen Methanococcus maripaludis and using formate as an additional electron donor, we isolate electron flow for methanogenesis from flux through Eha. We find that Eha does not function stoichiometrically for methanogenesis, implying that electron bifurcation must operate in vivo. We show that Eha is nevertheless essential, and a substoichiometric requirement for H2 suggests that its role is anaplerotic. Indeed, H2 via Eha stimulates methanogenesis from formate when intermediates are not otherwise replenished. These results fit the model for electron bifurcation, which renders the methanogenic pathway cyclic, and as such requires the replenishment of intermediates. Defining a role for Eha and verifying electron bifurcation provide a complete model of methanogenesis where all necessary electron inputs are accounted for. PMID:22872868

  17. Inhibition of acetoclastic methanogenesis in crude oil- and creosote-contaminated groundwater

    USGS Publications Warehouse

    Warren, E.; Bekins, B.A.; Godsy, E.M.; Smith, V.K.

    2004-01-01

    Results from a series of studies of methanogenic processes in crude oil- and creosote-contaminated aquifers indicated that acetoctastic methanogenesis is inhibited near non-aqueous sources. Acetoclastic methanogenesis was more susceptible to the toxic inhibition of crude oil and creosote than either hydrogen- or formate-utilizing methanogenesis. The effect of this toxic inhibition was apparent in the population of the methanogenic trophic groups near nonaqueous crude oil at the Bemidji, MN, site. At that site, acetoclastic methanogens were < 2/g within or near the oil where hydrogen- and formate-utilizing methanogens were 10-100/g. The geochemical effect of this toxic inhibition was the buildup of low molecular weight volatile acids, particularly acetate. Wastewater reactor studies indicated that this toxicity will result in a decrease in the biodegradation rate of contaminants at sites where toxic compounds are present.

  18. Geospatial Hydrochemical and Microbiological Implications on the Occurrence of Crude Oil Biodegradation and Methanogenesis

    NASA Astrophysics Data System (ADS)

    Shelton, J.; McIntosh, J. C.; Warwick, P.; McCray, J. E.

    2014-12-01

    Technologies that serve as a bridge between renewable energy and fossil fuels are needed to meet growing energy demands and to mitigate climate change. Many reservoirs contain difficult to produce residual and/or heavily biodegraded (i.e., geochemically altered) crude oil, which remains a relatively untapped resource. Production of this residual crude oil via unconventional methods, such as enhanced oil recovery (EOR), has offset some of the decline in conventional oil production. EOR is not efficient enough to recover all of the original oil in place, and some methods are not effective for very heavy crude oils. Stimulation of in-situ microorganisms to convert the residual crude oil to natural gas (i.e., microbial methane) is one promising strategy to "extract" residual and /or heavy crude oil. Although the hydrogeochemical conditions necessary for the occurrence of both crude oil biodegradation and microbial methanogenesis in various reservoirs have been studied, there are still gaps in research. Many hydrogeochemical factors have been researched individually (not as part of a multifactor or lithologically similar system) and little work has assessed the microbiological limitations of both processes. Our goal is to determine the hydrogeochemical and microbiological conditions required for maximum crude oil biodegradation and microbial methanogenesis across a lithologically similar unit. Produced water, oil, gas, and microbial biomass samples were collected from wells completed in the Paleocene—Eocene Wilcox Group in central Louisiana. Initial results indicate potential relationships between the amount of crude oil biodegradation, indicators of microbial methanogenesis, and aqueous geochemistry. For example, produced waters with the lowest salinity had the highest crude oil biodegradation, and wells exhibiting the most microbial methane generation produce waters with hydrogeochemical conditions most fit for methanogenesis to occur. In sampled wells displaying

  19. Solute concentrations influence microbial methanogenesis in coal-bearing strata of the Cherokee basin, USA

    SciTech Connect

    Kirk, Matthew F.; Wilson, Brien H.; Marquart, Kyle A.; Zeglin, Lydia H.; Vinson, David S.; Flynn, Theodore M.

    2015-11-18

    In this study, microorganisms have contributed significantly to subsurface energy resources by converting organic matter in hydrocarbon reservoirs into methane, the main component of natural gas. In this study, we consider environmental controls on microbial populations in coal-bearing strata of the Cherokee basin, an unconventional natural gas resource in southeast Kansas, USA. Pennsylvanian-age strata in the basin contain numerous thin (0.4–1.1 m) coalbeds with marginal thermal maturities (0.5–0.7% Ro) that are interbedded with shale and sandstone. We collected gas, water, and microbe samples from 16 commercial coalbed methane wells for geochemical and microbiological analysis. The water samples were Na–Cl type with total dissolved solids (TDS) content ranging from 34.9 to 91.3 g L–1. Gas dryness values [C1/(C2 + C3)] averaged 2640 and carbon and hydrogen isotope ratios of methane differed from those of carbon dioxide and water, respectively, by an average of 65 and 183‰. These values are thought to be consistent with gas that formed primarily by hydrogenotrophic methanogenesis. Results from cultivation assays and taxonomic analysis of 16S rRNA genes agree with the geochemical results. Cultivable methanogens were present in every sample tested, methanogen sequences dominate the archaeal community in each sample (avg 91%), and few archaeal sequences (avg 4.2%) were classified within Methanosarcinales, an order of methanogens known to contain methylotrophic methanogens. Although hydrogenotrophs appear dominant, geochemical and microbial analyses both indicate that the proportion of methane generated by acetoclastic methanogens increases with the solute content of formation water, a trend that is contrary to existing conceptual models. Consistent with this trend, beta diversity analyses show that archaeal diversity significantly correlates with formation water solute content. In contrast

  20. ENVIRONMENTAL FACTORS INFLUENCING METHANOGENESIS IN A SHALLOW ANOXIC AQUIFER: A FIELD AND LABORATORY STUDY

    EPA Science Inventory

    The environmental factors influencing methanogenesis in a shallow anoxic aquifer were probed in a combined field and laboratory study. Field data collected over a year revealed that in situ rates of methane production were depressed in winter and elevated in summer. Over the same...

  1. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: II. MODEL DEVELOPMENT AND VERIFICATION

    EPA Science Inventory

    A comprehensive dynamic model is presented that simulates methanogenesis and sulfate reduction in a continuously stirred tank reactor (CSTR). his model incorporates the complex chemistry of anaerobic systems. alient feature of the model is its ability to predict the effluent conc...

  2. METHANOGENESIS AND SULFATE REDUCTION IN CHEMOSTATS: II. MODEL DEVELOPMENT AND VERIFICATION

    EPA Science Inventory

    A comprehensive dynamic model is presented that simulates methanogenesis and sulfate reduction in a continuously stirred tank reactor (CSTR). This model incorporates the complex chemistry of anaerobic systems. A salient feature of the model is its ability to predict the effluent ...

  3. Methanogenesis and ATP synthesis in a protoplast system of Methanobacterium thermoautotrophicum.

    PubMed Central

    Mountfort, D O; Mörschel, E; Beimborn, D B; Schönheit, P

    1986-01-01

    When Methanobacterium thermoautotrophicum cells were incubated in 50 mM potassium phosphate buffer (pH 7.0) containing 1 M sucrose and autolysate from Methanobacterium wolfei, they were transformed into protoplasts. The protoplasts, which possessed no cell wall, lysed in buffer without sucrose. Unlike whole cells, the protoplasts did not show convoluted internal membrane structures. The protoplasts produced methane from H2-CO2 (approximately 1 mumol min-1 mg of protein-1) at about 50% the rate obtained for whole cells, and methanogenesis was coupled with ATP synthesis. Addition of the protonophore 3,5-di-tert-butyl-4-hydroxybenzylidenemalononitrile (SF-6847) to protoplast suspensions resulted in a dissipation of the membrane potential (delta psi), and this was accompanied by a parallel decrease in the rates of ATP synthesis and methanogenesis. In this respect protoplasts differed from whole cells in which ATP synthesis and methanogenesis were virtually unaffected by the addition of the protonophore. It is concluded that the insensitivity of whole cells to protonophores could be due to internal membrane structures. Membrane preparations produced from lysis of protoplasts or by sonication of whole cells gave comparatively low rates of methanogenesis (methylcoenzyme M methylreductase activity, less than or equal to 100 nmol of CH4 min-1 mg of protein-1), and no coupling with ATP synthesis could be demonstrated. Images PMID:3782030

  4. ENVIRONMENTAL FACTORS INFLUENCING METHANOGENESIS IN A SHALLOW ANOXIC AQUIFER: A FIELD AND LABORATORY STUDY

    EPA Science Inventory

    The environmental factors influencing methanogenesis in a shallow anoxic aquifer were probed in a combined field and laboratory study. Field data collected over a year revealed that "in situ" rates of methane production were depressed in winter and elevated in summer. Over the sa...

  5. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    NASA Astrophysics Data System (ADS)

    Maltby, J.; Sommer, S.; Dale, A. W.; Treude, T.

    2016-01-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0-25 cm below sea floor) at six stations (70, 145, 253, 407, 990 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic conditions in the bottom-near water. Net methane production (batch incubations) and sulfate reduction (35S-sulfate radiotracer incubation) were determined in the upper 0-25 cm b.s.f. of multiple cores from all stations, while deep hydrogenotrophic methanogenesis (> 30 cm b.s.f., 14C-bicarbonate radiotracer incubation) was determined in two gravity cores at selected sites (78 and 407 m). Furthermore, stimulation (methanol addition) and inhibition (molybdate addition) experiments were carried out to investigate the relationship between sulfate reduction and methanogenesis.

    Highest rates of methanogenesis and sulfate reduction in the surface sediments, integrated over 0-25 cm b.s.f., were observed on the shelf (70-253 m, 0.06-0.1 and 0.5-4.7 mmol m-2 d-1, respectively), while lowest rates were discovered at the deepest site (1024 m, 0.03 and 0.2 mmol m-2 d-1, respectively). The addition of methanol resulted in significantly higher surface methanogenesis activity, suggesting that the process was mostly based on non-competitive substrates - i.e., substrates not used by sulfate reducers. In the deeper sediment horizons, where competition was probably relieved due to the decrease of sulfate, the usage of competitive substrates was confirmed by the detection of hydrogenotrophic activity in the sulfate-depleted zone at the shallow shelf station (70 m).

    Surface methanogenesis appeared to be correlated to the availability of labile organic matter (C / N ratio) and organic carbon

  6. Microbial methanogenesis in the sulfate-reducing zone of surface sediments traversing the Peruvian margin

    NASA Astrophysics Data System (ADS)

    Maltby, J.; Sommer, S.; Dale, A. W.; Treude, T.

    2015-09-01

    We studied the concurrence of methanogenesis and sulfate reduction in surface sediments (0-25 cm below sea floor, cmbsf) at six stations (70, 145, 253, 407, 770 and 1024 m) along the Peruvian margin (12° S). This oceanographic region is characterized by high carbon export to the seafloor, creating an extensive oxygen minimum zone (OMZ) on the shelf, both factors that could favor surface methanogenesis. Sediments sampled along the depth transect traversed areas of anoxic and oxic conditions in the bottom-near water. Net methane production (batch incubations) and sulfate reduction (35S-sulfate radiotracer incubation) were determined in the upper 0-25 cmbsf of multicorer cores from all stations, while deep hydrogenotrophic methanogenesis (> 30 cmbsf, 14C-bicarbonate radiotracer incubation) was determined in two gravity cores at selected sites (78 and 407 m). Furthermore, stimulation (methanol addition) and inhibition (molybdate addition) experiments were carried out to investigate the relationship between sulfate reduction and methanogenesis. Highest rates of methanogenesis and sulfate reduction in the surface sediments, integrated over 0-25 cmbsf, were observed on the shelf (70-253 m, 0.06-0.1 and 0.5-4.7 mmol m-2 d-1, respectively), while lowest rates were discovered at the deepest site (1024 m, 0.03 and 0.2 mmol m-2 d-1, respectively). The addition of methanol resulted in significantly higher surface methanogenesis activity, suggesting that the process was mostly based on non-competitive substrates, i.e., substrates not used by sulfate reducers. In the deeper sediment horizons, where competition was probably relieved due to the decline of sulfate, the usage of competitive substrates was confirmed by the detection of hydrogenotrophic activity in the sulfate-depleted zone at the shallow shelf station (70 m). Surface methanogenesis appeared to be correlated to the availability of labile organic matter (C / N ratio) and organic carbon degradation (DIC production

  7. The relative importance of methanogenesis in the decomposition of organic matter in northern peatlands

    NASA Astrophysics Data System (ADS)

    Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

    2015-02-01

    Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 ± 13% of CO2 production) than in fens (64 ± 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 ± 1.3 and 3.7 ± 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 ± 2.8% and 82 ± 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 ± 0.2 mmol/L) relative to midbogs (1.6 ± 0.6 mmol/L) and methanogenesis was less important (42 ± 6.6% of total CO2 production relative to 55 ± 8.1%). We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 ± 7.0% and 64 ± 9.3%).

  8. Quantifying the Microbial Utilization of Methanogenesis and Methane Loss from Northern Wetlands

    NASA Astrophysics Data System (ADS)

    Corbett, J. E.; Tfaily, M.; Burdige, D.; Glaser, P. H.; Chanton, J.

    2014-12-01

    The importance of methanogenesis and percent of methane loss from the subsurface porewater in various northern wetland sites was quantified with isotope-mass balance equations. With equimolar amounts of CO2 and CH4 produced from methanogenesis, the amount of dissolved CO2 produced from methanogenesis as compared to other decomposition processes can be calculated and is equivalent to the amount of CH4 before loss due to ebullition, plant-mediated transport, and diffusion. This method was applied to porewater samples collected from various locations within permafrost collapse-scar bogs and northern peatlands. From the peatland sites, bogs produced less CO2-meth than fens (2.9 ± 1.3 mM and 3.7 ± 1.4 mM, respectively). Methanogenesis was a more utilized decomposition process in the bogs than the fens. However, greater amounts of CO2-meth found in fen sites was most likely due to the presence of more labile organic substrates resulting in greater overall production. More CH4 was lost in fens (89 ± 2.8%) than bogs (82 ± 5.3%) from plant-mediated transport as fens are dominated by vascular plants (Carex) while bogs are dominated by Sphagnum mosses. In permafrost sites, mid-bogs produced twice the amount of CO2-meth as bog moats (1.6 ± 0.63 mM and 0.82 ± 0.20 mM, respectively). Less methanogenesis was found in bog moats as recently thawed organic matter is exposed to initial decomposition processes and methane production grows over time. A similar amount of CH4 was lost from bog moats as mid bogs (63 ± 7.0% and 64 ± 9.3%, respectively) likely due to the greater density of vascular plants found within a bog moat.

  9. The Relative Importance of Methanogenesis in the Decomposition of Organic Matter in Northern Peatlands

    NASA Technical Reports Server (NTRS)

    Corbett, J. Elizabeth; Tfaily, Malak M.; Burdige, David J.; Glaser, Paul H.; Chanton, Jeffrey P.

    2015-01-01

    Using an isotope-mass balance approach and assuming the equimolar production of CO2 and CH4 from methanogenesis (e.g., anaerobic decomposition of cellulose), we calculate that the proportion of total CO2 production from methanogenesis varies from 37 to 83% across a variety of northern peatlands. In a relative sense, methanogenesis was a more important pathway for decomposition in bogs (80 +/- 13% of CO2 production) than in fens (64 +/- 5.7% of CO2 production), but because fens contain more labile substrates they may support higher CH4 production overall. The concentration of CO2 produced from methanogenesis (CO2-meth) can be considered equivalent to CH4 concentration before loss due to ebullition, plant-mediated transport, or diffusion. Bogs produced slightly less CO2-meth than fens (2.9 +/- 1.3 and 3.7 +/- 1.4 mmol/L, respectively). Comparing the quantity of CH4 present to CO2-meth, fens lost slightly more CH4 than bogs (89 +/- 2.8% and 82 +/- 5.3%, respectively) likely due to the presence of vascular plant roots. In collapsed permafrost wetlands, bog moats produced half the amount of CO2-meth (0.8 +/- 0.2mmol/L) relative to midbogs (1.6 +/- 0.6 mmol/L) and methanogenesis was less important (42 +/- 6.6% of total CO2 production relative to 55 +/- 8.1%).We hypothesize that the lower methane production potential in collapsed permafrost wetlands occurs because recently thawed organic substrates are being first exposed to the initial phases of anaerobic decomposition following collapse and flooding. Bog moats lost a comparable amount of CH4 as midbogs (63 +/- 7.0% and 64 +/- 9.3%).

  10. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 45 Public Welfare 3 2012-10-01 2012-10-01 false Awards not primarily for research. 650.6 Section 650.6 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...: Intellectual Property Rights The National Science Foundation claims no rights to any inventions or...

  11. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 45 Public Welfare 3 2013-10-01 2013-10-01 false Awards not primarily for research. 650.6 Section 650.6 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...: Intellectual Property Rights The National Science Foundation claims no rights to any inventions or...

  12. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 45 Public Welfare 3 2014-10-01 2014-10-01 false Awards not primarily for research. 650.6 Section 650.6 Public Welfare Regulations Relating to Public Welfare (Continued) NATIONAL SCIENCE FOUNDATION...: Intellectual Property Rights The National Science Foundation claims no rights to any inventions or...

  13. iDriving (Intelligent Driving)

    Energy Science and Technology Software Center (ESTSC)

    2012-09-17

    iDriving identifies the driving style factors that have a major impact on fuel economy. An optimization framework is used with the aim of optimizing a driving style with respect to these driving factors. A set of polynomial metamodels is constructed to reflect the responses produced in fuel economy by changing the driving factors. The optimization framework is used to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving stylesmore » in responses to actual driving conditions to improve fuel efficiency.« less

  14. iDriving (Intelligent Driving)

    SciTech Connect

    Malikopoulos, Andreas

    2012-09-17

    iDriving identifies the driving style factors that have a major impact on fuel economy. An optimization framework is used with the aim of optimizing a driving style with respect to these driving factors. A set of polynomial metamodels is constructed to reflect the responses produced in fuel economy by changing the driving factors. The optimization framework is used to develop a real-time feedback system, including visual instructions, to enable drivers to alter their driving styles in responses to actual driving conditions to improve fuel efficiency.

  15. Tylosin effect on methanogenesis in an anaerobic biomass from swine wastewater treatment.

    PubMed

    García-Sánchez, Liliana; Garzón-Zúñiga, Marco Antonio; Buelna, Gerardo; Estrada-Arriaga, Edson Baltazar

    2016-01-01

    The effect of different concentrations of tylosin on methane production was investigated: first methanogenesis in a biomass without contact with the antibiotic, and later the ability of the sludge to adapt to increasing concentrations of tylosin. Results showed that, for biomass that had no contact with the antibiotic, the presence of tylosin inhibits the generation of methane even at concentrations as small as 0.01 mg L(-1), and samples at concentrations above 0.5 mg L(-1) produced practically no methane, whereas, in the digesters acclimated in the presence of tylosin at a concentration of 0.01 to 0.065 mg L(-1), methanogenesis is not inhibited in the presence of antibiotic and the generation of methane is improved. This behaviour suggests the microorganisms have developed not only resistance to the antibiotic but also an ability to metabolize it. PMID:26819401

  16. Methanogenesis facilitated by geobiochemical iron cycle in a novel syntrophic methanogenic microbial community.

    PubMed

    Jiang, Shenghua; Park, Sunhwa; Yoon, Younggun; Lee, Ji-Hoon; Wu, Wei-Min; Phuoc Dan, Nguyen; Sadowsky, Michael J; Hur, Hor-Gil

    2013-09-01

    Production and emission of methane have been increasing concerns due to its significant effect on global climate change and the carbon cycle. Here we report facilitated methane production from acetate by a novel community of methanogens and acetate oxidizing bacteria in the presence of poorly crystalline akaganeite slurry. Comparative analyses showed that methanogenesis was significantly enhanced by added akaganeite and acetate was mostly stoichiometrically converted to methane. Electrons produced from anaerobic acetate oxidation are transferred to akaganeite nanorods that likely prompt the transformation into goethite nanofibers through a series of biogeochemical processes of soluble Fe(II) readsorption and Fe(III) reprecipitation. The methanogenic archaea likely harness the biotransformation of akaganeite to goethite by the Fe(III)-Fe(II) cycle to facilitate production of methane. These results provide new insights into biogeochemistry of iron minerals and methanogenesis in the environment, as well as the development of sustainable methods for microbial methane production. PMID:23919295

  17. Full title page pp iii Exsolution of nitrogen and argon by methanogenesis in Dutch ground water

    NASA Astrophysics Data System (ADS)

    Fortuin, Nienke P. M.; Willemsen, August

    2005-01-01

    Dutch ground water was sampled under high pressure in stainless steel vessels and analysed by gas chromatography for Ar, N 2, CH 4 and O 2. Results show a deficit N 2 and Ar concentrations combined with a high CH 4 concentration that are attributed to the occurrence of exsolution of Ar and N 2 during methanogenesis (the focus of this article). They also show N 2 and Ar in concentrations exceeding the concentration in equilibrium with atmospheric air that are caused by the entrapment and subsequent (partial) dissolution of excess air; in recent ground water, N 2 excesses also are caused by denitrification. PHREEQC model runs of methanogenesis at different pressures, with different amounts of organic matter decomposition and different amounts of initial dissolved N 2 show five features. Firstly, methanogenesis under lower hydrostatic pressures causes more N 2 and Ar exsolution than methanogenesis under higher hydrostatic pressures. Secondly, when little organic matter is decomposed (e.g. 1 mmol/l), the value taken for the fixed total pressure (between 1.05 and 3.0 atm.) influences mostly the N 2 and Ar concentration, and when much organic matter is decomposed (e.g. 16 mmol/l), the value taken for the fixed total pressure influences mostly the CH 4 concentration. Thirdly, in order to explain the observed gas concentrations, not more than 27 mmol of organic matter should be decomposed per litre of soil. Fourthly, the PHREEQC run with initial denitrification (initial N 2 pressure=1.0 atm.) fits the data better than the PHREEQC run without initial denitrification. Fifthly, the maximum total pressure of bubble formation is 3.0 atm. Analysed gas concentration profiles show that the greatest source of CH 4 is found up to approximately 20 m below surface. However, samples with CH 4 partial pressures >0.25 atm. were found up to a maximum average sampling screen depth of 81 m below surface.

  18. Enhanced methanogenesis from hexadecane and ethylbenzene under non-methanogenic conditions

    NASA Astrophysics Data System (ADS)

    Siegert, Michael; Cichocka, Danuta; Herrmann, Steffi; Richnow, Hans-Hermann; Springael, Dirk; Krüger, Martin

    2010-05-01

    Microbially enhanced oil recovery (MEOR) may provide access to remaining, but yet inaccessible petroleum in reservoirs. The microbial conversion of heavy hydrocarbon remnants into gaseous methane could at least provide access to energy which would otherwise be lost. On the other hand, methanogenesis could remove toxic hydrocarbons from contaminated aquifers and sediments. Therefore, sediment samples from a contaminated sea port basin were investigated to assess the in situ potential for methanogenic hydrocarbon degradation. Since this process is believed to be a sequential syntrophic procedure, non-methanogenic conditions were created in sediment microcosms to facilitate the first hydrocarbon attacking step. To achieve this, a high electron potential was created by the addition of ferrihydrite, manganese oxide, nitrate or sulfate as electron acceptors. Hexadecane, ethylbenzene or naphthalene were used as model carbon substrates. Methanogenesis evolved rapidly from set ups treated with iron and manganese, but not nitrate, reflecting the in situ conditions at the site. Surprisingly, on sulfate methanogenesis was neither inhibited nor significantly supported. Methane formation rates were the highest with hexadecane as substrate, followed by ethylbenzene and naphthalene. Methane was removed in high rates at the same time by anaerobic methanotrophs. The microbial community in situ and in vitro was dominated by members of the Geobacteraceae. Their methanogenic partners were quantified, targeting the genes encoding for the methyl coenzyme M reductase (mcrA). Methane consumption in the microcosms and the presence of methanotrophic anaerobes belonging to the ANME-1 and ANME-2 clusters suggest anaerobic methanotrophy as an accompanying process. mcrA genes belonging to the ANME-1 & -2 clusters were detected in lower copy numbers than the methanogenic mcrA, which is in good agreement with the activity measurements. These results indicate that the in situ stimulation of

  19. Methanogenesis in a thermophilic (58 degrees C) anaerobic digestor: Methanothrix sp. as an important aceticlastic methanogen

    SciTech Connect

    Zinder, S.H.; Cardwell, S.C.; Anguish, T.; Lee, M.; Koch, M.

    1984-04-01

    Aceticlastic methanogens and other microbial groups were enumerated in a 58 degrees C laboratory-scale (3 liter) anaerobic digestor which was fed air-classified municipal refuse, a lignocellulosic waste (loading rate = 1.8 to 2.7 g of volatile solids per liter per day: retention time = 10 days). Two weeks after start-up, Methanosarcina sp. was present in high numbers (10/sup 5/ to 10/sup 6/ CFU/ml) and autofluorescent Methanosarcina clumps were abundant in sludge. After 4 months of operation, numbers of Methanosarcina sp. dropped 2 to 3 orders of magnitude and large numbers (most probable number = 10/sup 6/ to 10/sup 7/ /ml) Methanothrix sp. were found. Methanothrix sp. had apparently displaced Methanosarcina sp. as the dominant aceticlastic methanogen. During the period when Methanothrix sp. was dominant, acetate concentrations varied between 0.3 and 1.5 mumol/ml during the daily feeding cycle, and acetate was the precursor of 63 to 66% of the methane produced during peak digestor methanogenesis. The apparent Km value obtained for methanogenesis from acetate, 0.3 mumol/ml, indicated that the aceticlastic methanogens were saturated for substrate during most of the digestor cycle. CO2 reducing methanogens were capable of methanogenesis at rates more than 12 times greater than those usually found in the digestor. Added propionate (4.5 mumol/ml) was metabolized slowly and slightly inhibited methanogenesis. Added n-butyrate, isobutyrate, or n-valerate (4.5 mumol/ml each) were broken down within 24 h. Isobutyrate was oxidized to acetate, a novel reaction possibly involving isomerization to n-butyrate. The rapid growth rate and versatile metabolism of Methanosarcina sp. make it a likely organism to be involved in start-up whereas the low Km value of Methanothrix sp. for acetate may cause it to be favored in stable digestors operated with long retention times.

  20. RUMINANT NUTRITION SYMPOSIUM: Use of genomics and transcriptomics to identify strategies to lower ruminal methanogenesis.

    PubMed

    McAllister, T A; Meale, S J; Valle, E; Guan, L L; Zhou, M; Kelly, W J; Henderson, G; Attwood, G T; Janssen, P H

    2015-04-01

    Globally, methane (CH4) emissions account for 40% to 45% of greenhouse gas emissions from ruminant livestock, with over 90% of these emissions arising from enteric fermentation. Reduction of carbon dioxide to CH4 is critical for efficient ruminal fermentation because it prevents the accumulation of reducing equivalents in the rumen. Methanogens exist in a symbiotic relationship with rumen protozoa and fungi and within biofilms associated with feed and the rumen wall. Genomics and transcriptomics are playing an increasingly important role in defining the ecology of ruminal methanogenesis and identifying avenues for its mitigation. Metagenomic approaches have provided information on changes in abundances as well as the species composition of the methanogen community among ruminants that vary naturally in their CH4 emissions, their feed efficiency, and their response to CH4 mitigators. Sequencing the genomes of rumen methanogens has provided insight into surface proteins that may prove useful in the development of vaccines and has allowed assembly of biochemical pathways for use in chemogenomic approaches to lowering ruminal CH4 emissions. Metagenomics and metatranscriptomic analysis of entire rumen microbial communities are providing new perspectives on how methanogens interact with other members of this ecosystem and how these relationships may be altered to reduce methanogenesis. Identification of community members that produce antimethanogen agents that either inhibit or kill methanogens could lead to the identification of new mitigation approaches. Discovery of a lytic archaeophage that specifically lyses methanogens is 1 such example. Efforts in using genomic data to alter methanogenesis have been hampered by a lack of sequence information that is specific to the microbial community of the rumen. Programs such as Hungate1000 and the Global Rumen Census are increasing the breadth and depth of our understanding of global ruminal microbial communities, steps that

  1. Impaired Driving

    MedlinePlus

    ... Risk Factors BAC Effects Prevention Additional Resources How big is the problem? In 2014, 9,967 people ... Driving: A Threat to Everyone (October 2011) Additional Data Drunk Driving State Data and Maps Motor Vehicle ...

  2. Drugged Driving

    MedlinePlus

    ... Infographics » Drugged Driving Drugged Driving Email Facebook Twitter Text Description of Infographic Top Right Figure : In 2009, ... crash than those who don't smoke. Bottom Text: Develop Social Strategies Offer to be a designated ...

  3. Long-Lasting Gene Conversion Shapes the Convergent Evolution of the Critical Methanogenesis Genes

    PubMed Central

    Wang, Sishuo; Chen, Youhua; Cao, Qinhong; Lou, Huiqiang

    2015-01-01

    Methanogenesis and its key small-molecule methyltransferase Mtr complex are poorly understood despite their pivotal role in Earth’s global carbon cycle. Mtr complex is encoded by a conserved mtrEDCBAFGH operon in most methanogens. Here we report that two discrete lineages, Methanococcales and Methanomicrobiales, have a noncanonical mtr operon carrying two copies of mtrA resulting from an ancient duplication. Compared to mtrA-1, mtrA-2 acquires a distinct transmembrane domain through domain shuffling and gene fusion. However, the nontransmembrane domains (MtrA domain) of mtrA-1 and mtrA-2 are homogenized by gene conversion events lasting throughout the long history of these extant methanogens (over 2410 million years). Furthermore, we identified a possible recruitment of ancient nonmethanogenic methyltransferase genes to establish the methanogenesis pathway. These results not only provide novel evolutionary insight into the methanogenesis pathway and methyltransferase superfamily but also suggest an unanticipated long-lasting effect of gene conversion on gene evolution in a convergent pattern. PMID:26384370

  4. Methanogenesis and the Wood-Ljungdahl Pathway: An Ancient, Versatile, and Fragile Association.

    PubMed

    Borrel, Guillaume; Adam, Panagiotis S; Gribaldo, Simonetta

    2016-01-01

    Methanogenesis coupled to the Wood-Ljungdahl pathway is one of the most ancient metabolisms for energy generation and carbon fixation in the Archaea. Recent results are sensibly changing our view on the diversity of methane-cycling capabilities in this Domain of Life. The availability of genomic sequences from uncharted branches of the archaeal tree has highlighted the existence of novel methanogenic lineages phylogenetically distant to previously known ones, such as the Methanomassiliicoccales. At the same time, phylogenomic analyses have suggested a methanogenic ancestor for all Archaea, implying multiple independent losses of this metabolism during archaeal diversification. This prediction has been strengthened by the report of genes involved in methane cycling in members of the Bathyarchaeota (a lineage belonging to the TACK clade), representing the first indication of the presence of methanogenesis outside of the Euryarchaeota. In light of these new data, we discuss how the association between methanogenesis and the Wood-Ljungdahl pathway appears to be much more flexible than previously thought, and might provide information on the processes that led to loss of this metabolism in many archaeal lineages. The combination of environmental microbiology, experimental characterization and phylogenomics opens up exciting avenues of research to unravel the diversity and evolutionary history of fundamental metabolic pathways. PMID:27189979

  5. Methanogenesis from choline by a coculture of Desulfovibrio sp. and Methanosarcina barkeri

    SciTech Connect

    Fiebig, K.; Gottschalk, G.

    1983-01-01

    A sulfate-reducing vibrio was isolated from a methanogenic enrichment with choline as the sole added organic substrate. This oganism was identified as a member of the genus Desulfovibrio and was designated Desulfovibrio strain G1. In a defined medium devoid of sulfate, a pure culture of Desulfovibrio strain G1 fermented choline to trimethylamine, acetate, and ethanol. In the presence of sulfate, more acetate and less ethanol were formed from choline than in the absence of sulfate. When grown in a medium containing sulfate, a coculture of Desulfovibrio strain G1 and Methanosarcina barkeri strain Fusaro degraded chloline almost completely to methane, ammonia, and hydrogen sulfide and presumably to carbon dioxide. Methanogenesis occurred in two distinct phases separated by a lag of about 6 days. During the first phase of methanogenesis choline was completely converted to trimethylamine, acetate, hydrogen sulfide, and traces of ethanol by the desulfovibrio.M. barkeri fermented trimethylamine to methane, ammonia, and presumably carbon dioxide via dimethyl- and methylamine as intermediates. Simultaneously, about 60% of the acetate expected was metabolized. In the second phase of methanogenesis, the residual acetate was almost completely catabolized.

  6. High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors.

    PubMed

    Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

    2016-01-01

    A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA-stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures. PMID:27490246

  7. An EGSB-SBR based process for coupling methanogenesis and shortcut nitrogen removal.

    PubMed

    Bai, Cui; Zhang, Daijun; He, Qiang; Lu, Peili; Ai, Hainan

    2013-01-01

    An integrated process consisting of an anaerobic/anoxic expanded granular sludge bed (EGSB) reactor and an aerobic sequencing batch reactor (SBR) was developed by a mode of sequencing batch operation, in which methanogenesis, denitrification and anammox were coupled in EGSB with methanogenesis first, then denitrification and anammox simultaneously, and partial nitrification occurred in SBR for providing nitrite to EGSB. This process extended the application of the anammox process to the treatment of wastewater containing high concentrations of chemical oxygen demand (COD) and ammonium. When the volumetric exchange ratio between EGSB and SBR was controlled at 57% with the influent pH at 6-8, 74.38-83.65% of NH(4)(+)-N, 72.68-83.12% of total nitrogen (TN) and 88.34-98.86% of COD were removed in a range of 200-4,500 mg/L COD and 40-90 mg/L NH(4)(+)-N respectively. TN removal by anammox and shortcut denitrification was 26.35-58.64 and 0-32.80% of the removed nitrogen, respectively. The results showed that the contribution of anammox gradually decreased with an increase in the C/N ratio of influent, whereas the reverse was true for shortcut denitrification. The COD removal by methanogenesis was 70.89-98.79% of the removed COD, and increased with increasing C/N ratio. PMID:24135114

  8. High-rate, High Temperature Acetotrophic Methanogenesis Governed by a Three Population Consortium in Anaerobic Bioreactors

    PubMed Central

    Ho, Dang; Jensen, Paul; Gutierrez-Zamora, Maria-Luisa; Beckmann, Sabrina; Manefield, Mike; Batstone, Damien

    2016-01-01

    A combination of acetate oxidation and acetoclastic methanogenesis has been previously identified to enable high-rate methanogenesis at high temperatures (55 to 65°C), but this capability had not been linked to any key organisms. This study combined RNA–stable isotope probing on 13C-labelled acetate and 16S amplicon sequencing to identify the active micro-organisms involved in high-rate methanogenesis. Active biomass was harvested from three bench-scale thermophilic bioreactors treating waste activated sludge at 55, 60 and 65°C, and fed with 13-C labelled and 12C-unlabelled acetate. Acetate uptake and cumulative methane production were determined and kinetic parameters were estimated using model-based analysis. Pyrosequencing performed on 13C- enriched samples indicated that organisms accumulating labelled carbon were Coprothermobacter (all temperatures between 55 and 65°C), acetoclastic Methanosarcina (55 to 60°C) and hydrogenotrophic Methanothermobacter (60 to 65°C). The increased relative abundance of Coprothermobacter with increased temperature corresponding with a shift to syntrophic acetate oxidation identified this as a potentially key oxidiser. Methanosarcina likely acts as both a hydrogen utilising and acetoclastic methanogen at 55°C, and is replaced by Methanothermobacter as a hydrogen utiliser at higher temperatures. PMID:27490246

  9. Experimental evaluation of the metabolic reversibility of ANME-2d between anaerobic methane oxidation and methanogenesis.

    PubMed

    Ding, Jing; Fu, Liang; Ding, Zhao-Wei; Lu, Yong-Ze; Cheng, Shuk H; Zeng, Raymond J

    2016-07-01

    The "reverse methanogenesis" hypothesis as the metabolic pathway of AOM has recently been supported in the novel ANME lineage ANME-2d in denitrifying anaerobic methane oxidation (DAMO). However, no previous studies have experimentally evaluated the reversal of methane oxidation and methane production in this archaea. In the present study, the metabolic reversibility of ANME-2d from AOM to methanogenesis was evaluated using H2/CO2 and acetate as substrates. The results showed that the system produced methane from H2/CO2 but not from acetate. However, the clone library and real-time PCR analysis of the culture showed that both the percentage and quantity of ANME-2d decreased significantly under this condition, while methanogen abundance increased. Further high-throughput sequencing results showed that the archaea community did not change at the fourth day after H2/CO2 was supplied, but changed profoundly after methanogenesis took place for 3 days. The percentage of DAMO archaea in the total archaea decreased obviously, while more methanogens grew up during this period. Comparatively, the bacteria community changed profoundly at the fourth day. These results indicated that ANME-2d might not reverse its metabolism to produce methane from H2/CO2 or acetate. After archaea were returned to DAMO conditions, DAMO activity decreased and the amount of ANME-2d continued to fall, implying that the lineage had suffered from severe injury and required a long recovery time. PMID:27026178

  10. Experimental burial inhibits methanogenesis and anaerobic decomposition in water-saturated peats.

    PubMed

    Blodau, Christian; Siems, Melanie; Beer, Julia

    2011-12-01

    A mechanistic understanding of carbon (C) sequestration and methane (CH(4)) production is of great interest due to the importance of these processes for the global C budget. Here we demonstrate experimentally, by means of column experiments, that burial of water saturated, anoxic bog peat leads to inactivation of anaerobic respiration and methanogenesis. This effect can be related to the slowness of diffusive transport of solutes and evolving energetic constraints on anaerobic respiration. Burial lowered decomposition constants in homogenized peat sand mixtures from about 10(-5) to 10(-7) yr(-1), which is considerably slower than previously assumed, and methanogenesis slowed down in a similar manner. The latter effect could be related to acetoclastic methanogenesis approaching a minimum energy quantum of -25 kJ mol(-1) (CH(4)). Given the robustness of hydraulic properties that locate the oxic-anoxic boundary near the peatland surface and constrain solute transport deeper into the peat, this effect has likely been critical for building the peatland C store and will continue supporting long-term C sequestration in northern peatlands even under moderately changing climatic conditions. PMID:21958021

  11. Inhibition of Acetoclastic Methanogenesis in Crude Oil- and Creosote-Contaminated Groundwater

    USGS Publications Warehouse

    Warren, E.; Bekins, B.A.; Godsy, E.M.; Smith, V.K.

    2003-01-01

    The inhibition of acetoclastic methanogenesis in crude oil- and creosote-contaminated groundwater was studied. The crude oil and water-soluble components of creosote contributed to the inhibition of acetoclastic methanogens. Acetoclastic methanogenesis was much more susceptible to the toxic inhibition of crude oil and creosote than either hydrogen- or formate-utilizing methanogenesis. The effect of this toxic inhibition was apparent in the population of the methanogenic trophic groups near nonaqueous crude oil at the Bemidji, MN, site. At a crude oil-contaminated site, numbers of acetoclastic methanogens found close to crude oil were 100 times fewer than those of hydrogen- and formate-utilizing methanogens. In laboratory toxicity assays, crude oil collected from the site inhibited methane production from acetate but not from formate or hydrogen. Toxicity assays with aqueous creosote extract completely inhibited acetate utilization over the range of tested dilutions but only mildly affected formate and hydrogen utilization. Wastewater reactor studies indicated that this toxicity would result in a decrease in the biodegradation rate of contaminants at sites where toxic compounds are present.

  12. Methanogenesis and the Wood–Ljungdahl Pathway: An Ancient, Versatile, and Fragile Association

    PubMed Central

    Borrel, Guillaume; Adam, Panagiotis S.; Gribaldo, Simonetta

    2016-01-01

    Methanogenesis coupled to the Wood–Ljungdahl pathway is one of the most ancient metabolisms for energy generation and carbon fixation in the Archaea. Recent results are sensibly changing our view on the diversity of methane-cycling capabilities in this Domain of Life. The availability of genomic sequences from uncharted branches of the archaeal tree has highlighted the existence of novel methanogenic lineages phylogenetically distant to previously known ones, such as the Methanomassiliicoccales. At the same time, phylogenomic analyses have suggested a methanogenic ancestor for all Archaea, implying multiple independent losses of this metabolism during archaeal diversification. This prediction has been strengthened by the report of genes involved in methane cycling in members of the Bathyarchaeota (a lineage belonging to the TACK clade), representing the first indication of the presence of methanogenesis outside of the Euryarchaeota. In light of these new data, we discuss how the association between methanogenesis and the Wood–Ljungdahl pathway appears to be much more flexible than previously thought, and might provide information on the processes that led to loss of this metabolism in many archaeal lineages. The combination of environmental microbiology, experimental characterization and phylogenomics opens up exciting avenues of research to unravel the diversity and evolutionary history of fundamental metabolic pathways. PMID:27189979

  13. Amphotericin primarily kills yeast by simply binding ergosterol

    PubMed Central

    Gray, Kaitlyn C.; Palacios, Daniel S.; Dailey, Ian; Endo, Matthew M.; Uno, Brice E.; Wilcock, Brandon C.; Burke, Martin D.

    2012-01-01

    Amphotericin B (AmB) is a prototypical small molecule natural product that can form ion channels in living eukaryotic cells and has remained refractory to microbial resistance despite extensive clinical utilization in the treatment of life-threatening fungal infections for more than half a century. It is now widely accepted that AmB kills yeast primarily via channel-mediated membrane permeabilization. Enabled by the iterative cross-coupling-based synthesis of a functional group deficient derivative of this natural product, we have discovered that channel formation is not required for potent fungicidal activity. Alternatively, AmB primarily kills yeast by simply binding ergosterol, a lipid that is vital for many aspects of yeast cell physiology. Membrane permeabilization via channel formation represents a second complementary mechanism that further increases drug potency and the rate of yeast killing. Collectively, these findings (i) reveal that the binding of a physiologically important microbial lipid is a powerful and clinically validated antimicrobial strategy that may be inherently refractory to resistance, (ii) illuminate a more straightforward path to an improved therapeutic index for this clinically vital but also highly toxic antifungal agent, and (iii) suggest that the capacity for AmB to form protein-like ion channels might be separable from its cytocidal effects. PMID:22308411

  14. Pile Driving

    NASA Technical Reports Server (NTRS)

    1987-01-01

    Machine-oriented structural engineering firm TERA, Inc. is engaged in a project to evaluate the reliability of offshore pile driving prediction methods to eventually predict the best pile driving technique for each new offshore oil platform. Phase I Pile driving records of 48 offshore platforms including such information as blow counts, soil composition and pertinent construction details were digitized. In Phase II, pile driving records were statistically compared with current methods of prediction. Result was development of modular software, the CRIPS80 Software Design Analyzer System, that companies can use to evaluate other prediction procedures or other data bases.

  15. Multiple evidence for methylotrophic methanogenesis as the dominant methanogenic pathway in hypersaline sediments from the Orca Basin, Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Zhuang, Guang-Chao; Elling, Felix J.; Nigro, Lisa M.; Samarkin, Vladimir; Joye, Samantha B.; Teske, Andreas; Hinrichs, Kai-Uwe

    2016-08-01

    Among the most extreme habitats on Earth, dark, deep, anoxic brines host unique microbial ecosystems that remain largely unexplored. As the terminal step of anaerobic degradation of organic matter, methanogenesis is a potentially significant but poorly constrained process in deep-sea hypersaline environments. We combined biogeochemical and phylogenetic analyses with incubation experiments to unravel the origin of methane in the hypersaline sediments of Orca Basin in the northern Gulf of Mexico. Substantial concentrations of methane, up to 3.4 mM, coexisted with high concentrations of sulfate from 16 to 43 mM in two sediment cores retrieved from the northern and southern parts of Orca Basin. The strong depletion of 13C in methane (-77‰ to -89‰) points towards a biological source. While low concentrations of competitive substrates limited the significance of hydrogenotrophic and acetoclastic methanogenesis, the presence of non-competitive methylated substrates (methanol, trimethylamine, dimethyl sulfide, dimethylsulfoniopropionate) supported the potential for methane generation through methylotrophic methanogenesis. Thermodynamic calculations demonstrated that hydrogenotrophic and acetoclastic methanogenesis were unlikely to occur under in situ conditions, while methylotrophic methanogenesis from a variety of substrates was highly favorable. Likewise, carbon isotope relationships between methylated substrates and methane suggested methylotrophic methanogenesis was the major source of methane. Stable and radio-isotope tracer experiments with 13C-labeled bicarbonate, acetate and methanol and 14C-labeled methylamine indicated that methylotrophic methanogenesis was the predominant methanogenic pathway. Based on 16S rRNA gene sequences, halophilic methylotrophic methanogens related to the genus Methanohalophilus dominated the benthic archaeal community in the northern basin and also occurred in the southern basin. High abundances of methanogen lipid biomarkers such as

  16. Pathogenic Leptospira interrogans Exoproteins Are Primarily Involved in Heterotrophic Processes

    PubMed Central

    Eshghi, Azad; Pappalardo, Elisa; Hester, Svenja; Thomas, Benjamin; Pretre, Gabriela

    2015-01-01

    Leptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins. PMID:25987703

  17. Pathogenic Leptospira interrogans exoproteins are primarily involved in heterotrophic processes.

    PubMed

    Eshghi, Azad; Pappalardo, Elisa; Hester, Svenja; Thomas, Benjamin; Pretre, Gabriela; Picardeau, Mathieu

    2015-08-01

    Leptospirosis is a life-threatening and emerging zoonotic disease with a worldwide annual occurrence of more than 1 million cases. Leptospirosis is caused by spirochetes belonging to the genus Leptospira. The mechanisms of disease manifestation in the host remain elusive, and the roles of leptospiral exoproteins in these processes have yet to be determined. Our aim in this study was to assess the composition and quantity of exoproteins of pathogenic Leptospira interrogans and to construe how these proteins contribute to disease pathogenesis. Label-free quantitative mass spectrometry of proteins obtained from Leptospira spirochetes cultured in vitro under conditions mimicking infection identified 325 exoproteins. The majority of these proteins are conserved in the nonpathogenic species Leptospira biflexa, and proteins involved in metabolism and energy-generating functions were overrepresented and displayed the highest relative abundance in culture supernatants. Conversely, proteins of unknown function, which represent the majority of pathogen-specific proteins (presumably involved in virulence mechanisms), were underrepresented. Characterization of various L. interrogans exoprotein mutants in the animal infection model revealed host mortality rates similar to those of hosts infected with wild-type L. interrogans. Collectively, these results indicate that pathogenic Leptospira exoproteins primarily function in heterotrophic processes (the processes by which organisms utilize organic substances as nutrient sources) to maintain the saprophytic lifestyle rather than the virulence of the bacteria. The underrepresentation of proteins homologous to known virulence factors, such as toxins and effectors in the exoproteome, also suggests that disease manifesting from Leptospira infection is likely caused by a combination of the primary and potentially moonlight functioning of exoproteins. PMID:25987703

  18. Effect of Gynosaponin on Rumen In vitro Methanogenesis under Different Forage-Concentrate Ratios

    PubMed Central

    Manatbay, Bakhetgul; Cheng, Yanfen; Mao, Shengyong; Zhu, Weiyun

    2014-01-01

    The study aimed to investigate the effects of gynosaponin on in vitro methanogenesis under different forage-concentrate ratios (F:C ratios). Experiment was conducted with two kinds of F:C ratios (F:C = 7:3 and F:C = 3:7) and gynosaponin addition (0 mg and 16 mg) in a 2×2 double factorial design. In the presence of gynosaponin, methane production and acetate concentration were significantly decreased, whereas concentration of propionate tended to be increased resulting in a significant reduction (p<0.05) of acetate:propionate ratio (A:P ratio), in high-forage substrate. Gynosaponin treatment increased (p<0.05) the butyrate concentration in both F:C ratios. Denaturing gradient gel electrophoresis (DGGE) analysis showed there was no apparent shift in the composition of total bacteria, protozoa and methanogens after treated by gynosaponin under both F:C ratios. The real-time polymerase chain reaction (PCR) analysis indicated that variable F:C ratios significantly affected the abundances of Fibrobacter succinogenes, Rumninococcus flavefaciens, total fungi and counts of protozoa (p<0.05), but did not affect the mcrA gene copies of methanogens and abundance of total bacteria. Counts of protozoa and abundance of F.succinogenes were decreased significantly (p<0.05), whereas mcrA gene copies of methanogens were decreased slightly (p<0.10) in high-forage substrate after treated by gynosaponin. However, gynosaponin treatment under high-concentrate level did not affect the methanogenesis, fermentation characteristics and tested microbes. Accordingly, overall results suggested that gynosaponin supplementation reduced the in vitro methanogenesis and improved rumen fermentation under high-forage condition by changing the abundances of related rumen microbes. PMID:25083102

  19. The Chemical Interplay of Serpentinization, Methanogenesis, and Carbonate Formation at 200C and 300 bar

    NASA Astrophysics Data System (ADS)

    Jones, L.; Rosenbauer, R.; Oze, C.

    2008-12-01

    Serpentinization (olivine hydrolysis) is the primary process contributing to abiotic generation of elemental hydrogen (H2) in active mid-ocean ridge hydrothermal systems and forearc environments. Carbon dioxide in these types of systems reacts with serpentinization-derived H2 to produce methane (CH4) and with cations in seawater (Ca2+, Mg2+, Fe2+) to precipitate carbonate minerals. Despite a growing body of field and experimental evidence, the reaction pathways, kinetics, and geochemical interplay of serpentinization, methanogenesis and carbonate formation are not fully understood. Here, we evaluated the reaction kinetics of CH4 versus carbonate genesis during serpentinization of average Earth olivines (Fo~90) under pressure-temperature (PT) conditions similar to mid-ocean ridge and forearc environments. Laboratory experiments were preformed at identical T and P conditions (200°C and 300 bar) using flexible gold reaction-cells in hydrothermal autoclaves located in the Water- Rock Interaction Laboratory at the U.S. Geological Survey in Menlo Park, CA. The experiments demonstrate that CH4 production was minimal in CO2-rich fluids and that CH4 generation was enhanced in a CO2-limited experiment producing an end-member CH4 concentration of 44 μM after 860 hours. Equilibrium thermodynamics and reaction rates observed in these experiments demonstrate that carbonate precipitation is favored in CO2-saturated systems and methanogenesis is hindered. These results highlight the competition between methanogenesis and carbonate production in hydrothermal environments leading to the conclusion that the production of CH4 is greater when the concentration of CO2 is undersaturated with respect to carbonate equilibrium.

  20. Zero-valent and charged metals combined with anaerobic bacteria in methanogenesis

    SciTech Connect

    Sysak, J.C.

    1995-12-31

    Zero-valent iron has been observed to effect the decomposition of alkyl and aromatic halides with the reduction to the corresponding hydrocarbon. The reaction is of interest in conjunction with bioredmediation of soil contaminated with CHCl{sub 3} and other environmentally sensitive halides. This work examines the effects of anaerobic bacteria in conjunction with various metals on the methanogenesis of pollutants as well as biomass of various types. The results of the addition of Ni{sup 2+} to the methyl coenzyme M reductase system was investigated and the results presented involving a number of bacterial species in addition to a mixed sewage culture immaculate.

  1. Sulfate Reduction and Methanogenesis in the Sediment of a Saltmarsh on the East Coast of the United Kingdom

    PubMed Central

    Senior, Eric; Lindström, E. Börje; Banat, Ibrahim M.; Nedwell, David B.

    1982-01-01

    The rates of sulfate reduction, methanogenesis, and methane loss were measured in saltmarsh sediment at monthly intervals. In addition, dissolved methane and sulfate concentrations together with pS2− and pH were determined. Methane formation from carbon dioxide, but not from acetate, was detected within the same horizon of sediment where sulfate reduction was most active. Sulfate reduction was about three orders of magnitude greater than annual methanogenesis. The two processes were not separated either spatially or temporally, but occurred within the same layer of sediment at the same time of the year. Their coexistence did not seem to be the result of sulfate-depleted microenvironments within which methanogenesis could occur, but the methanogenic bacteria persisted at very low rates of activity within the same environment as the sulfate reducers. PMID:16346022

  2. Phylogenomic Data Support a Seventh Order of Methylotrophic Methanogens and Provide Insights into the Evolution of Methanogenesis

    PubMed Central

    Borrel, Guillaume; O’Toole, Paul W.; Harris, Hugh M.B.; Peyret, Pierre; Brugère, Jean-François; Gribaldo, Simonetta

    2013-01-01

    Increasing evidence from sequence data from various environments, including the human gut, suggests the existence of a previously unknown putative seventh order of methanogens. The first genomic data from members of this lineage, Methanomassiliicoccus luminyensis and “Candidatus Methanomethylophilus alvus,” provide insights into its evolutionary history and metabolic features. Phylogenetic analysis of ribosomal proteins robustly indicates a monophyletic group independent of any previously known methanogenic order, which shares ancestry with the Marine Benthic Group D, the Marine Group II, the DHVE2 group, and the Thermoplasmatales. This phylogenetic position, along with the analysis of enzymes involved in core methanogenesis, strengthens a single ancient origin of methanogenesis in the Euryarchaeota and indicates further multiple independent losses of this metabolism in nonmethanogenic lineages than previously suggested. Genomic analysis revealed an unprecedented loss of the genes coding for the first six steps of methanogenesis from H2/CO2 and the oxidative part of methylotrophic methanogenesis, consistent with the fact that M. luminyensis and “Ca. M. alvus” are obligate H2-dependent methylotrophic methanogens. Genomic data also suggest that these methanogens may use a large panel of methylated compounds. Phylogenetic analysis including homologs retrieved from environmental samples indicates that methylotrophic methanogenesis (regardless of dependency on H2) is not restricted to gut representatives but may be an ancestral characteristic of the whole order, and possibly also of ancient origin in the Euryarchaeota. 16S rRNA and McrA trees show that this new order of methanogens is very diverse and occupies environments highly relevant for methane production, therefore representing a key lineage to fully understand the diversity and evolution of methanogenesis. PMID:23985970

  3. Ecology of methanogenesis in two hypersaline biocoenoses: Great Salt Lake and a San Francisco Bay saltern

    SciTech Connect

    Paterek, J.R.

    1983-01-01

    Enrichment cultures were prepared from sediment and brine samples from two hypersaline ecosystems, Great Salt Lake in Utah and a solar saltern located in San Francisco Bay. Methane production was greater when enriched with the biopolymer chitin than with cellulose or peptone. Organisms indigenous to hypersaline ecosystems, brine shrimp (Artemia sp.), halobacteria (Halobacterium sp. and Halococcus sp.) and halophilic algae (Dunaliella sp. and others) were cultivated and added to anaerobic and aerobic microcosms prepared with brine and sediment from the ecosystems studied. Methane production and the concentration of the methanogenic precursor, trimethylamine were greatest with brine shrimp as a supplement. Choline produced the highest concentrations of methane in all samples examined. A number of marine-related ecosystems were also examined for their ability to support methanogenesis at various salinities. Methanogenesis occurred at sea water salinity in the majority of samples, and methane production was observed from three sites at salinity found in Great Salt Lake brine. A halophilic methanogenic bacterium species was isolated from both Great Salt Lake and the San Francisco Bay solar saltern sediments. Cells are irregular, nonmotile cocci, approximately 1.0uM in diameter and stain gram negative.

  4. Education and production. Chicken manure methanogenesis. 1. Selective inhibition of acetate conversion to methane

    SciTech Connect

    Dosoretz, C.; Lamed, R.

    1987-01-01

    Thermophilic (55 C) methanogenesis of chicken manure was examined after prolonged acclimatization procedures. Unusual steady state parameters were obtained in quasi-continuous operations: volatile solids = 24 to 96 g/L, retention time = 5 to 20 days, in which methane was continuously formed (.5 to .7/L.L/day), H/sub 2/ was not present, but acetate (19 to 222 mM), other fatty acids, and ammonia nitrogen (800 to 2,830 mg/L) levels were very high. Tracer (2-(/sup 14/C) acetate) studies showed that acetate accumulation resulted from inhibition of acetate conversion to methane. Enumeration of H/sub 2/-oxidizing methanogenic populations as well as acetate-degrading methanogens indicated adequate populations in chicken manure relative to cow manure. Thus, measurement of acetate degradation activities indicated its inhibition, whereas bacterial enumeration studies indicated no lack of methanogenic bacterial populations. These findings are in disagreement with the uninhibited fast rate of aceticlastic methanogenesis in cow manure. Therefore, it may be concluded that the methanogenic populations are unchanged, but their capacity to decarboxylate acetate is somehow blocked, which would lead to concomittant accumulation of acetate in addition to the formation of CO/sub 2/ and H/sub 2//CO/sub 2/-derived methane as the major fermentation end products. (Refs. 33).

  5. Pilot-scale two-stage process: a combination of acidogenic hydrogenesis and methanogenesis.

    PubMed

    Han, S K; Kim, S H; Kim, H W; Shin, H S

    2005-01-01

    This study was performed to optimize both acidogenic hydrogenesis and methanogenesis, and then to develop a pilot-scale two-stage process producing not only CH4 but also H2. Firstly, acidogenic hydrogenesis of food waste was examined in pilot-scale leaching-bed reactors using dilution rate (D) as a tool to improve the environmental conditions. The maximum efficiency of 71.4% was obtained by adjusting D from 4.5 to 2.5 d(-1) depending on the state of degradation. Secondly, the wastewater from acidogenic hydrogenesis was converted to CH4 in a pilot-scale UASB reactor. The COD removal efficiency exceeded 95% up to the loading rates of 13.1 g COD/Ld, which corresponded to HRT of 0.25 d (6 h). Lastly, a pilot-scale two-stage process was devised based on a combination of acidogenic hydrogenesis and methanogenesis. Over 120 days, the pilot-scale process resulted in large VS reduction of 70.9% at the high loading rate of 12.5 kg VS/m3/d in a short SRT of 8 days. PMID:16180419

  6. Limits to Dihydrogen Incorporation into Electron Sinks Alternative to Methanogenesis in Ruminal Fermentation.

    PubMed

    Ungerfeld, Emilio M

    2015-01-01

    Research is being conducted with the objective of decreasing methane (CH4) production in the rumen, as methane emissions from ruminants are environmentally damaging and a loss of digestible energy to ruminants. Inhibiting ruminal methanogenesis generally results in accumulation of dihydrogen (H2), which is energetically inefficient and can inhibit fermentation. It would be nutritionally beneficial to incorporate accumulated H2 into propionate or butyrate production, or reductive acetogenesis. The objective of this analysis was to examine three possible physicochemical limitations to the incorporation of accumulated H2 into propionate and butyrate production, and reductive acetogenesis, in methanogenesis-inhibited ruminal batch and continuous cultures: (i) Thermodynamics; (ii) Enzyme kinetics; (iii) Substrate kinetics. Batch (N = 109) and continuous (N = 43) culture databases of experiments with at least 50% inhibition in CH4 production were used in this meta-analysis. Incorporation of accumulated H2 into propionate production and reductive acetogenesis seemed to be thermodynamically feasible but quite close to equilibrium, whereas this was less clear for butyrate. With regard to enzyme kinetics, it was speculated that hydrogenases of ruminal microorganisms may have evolved toward high-affinity and low maximal velocity to compete for traces of H2, rather than for high pressure accumulated H2. Responses so far obtained to the addition of propionate production intermediates do not allow distinguishing between thermodynamic and substrate kinetics control. PMID:26635743

  7. Limits to Dihydrogen Incorporation into Electron Sinks Alternative to Methanogenesis in Ruminal Fermentation

    PubMed Central

    Ungerfeld, Emilio M.

    2015-01-01

    Research is being conducted with the objective of decreasing methane (CH4) production in the rumen, as methane emissions from ruminants are environmentally damaging and a loss of digestible energy to ruminants. Inhibiting ruminal methanogenesis generally results in accumulation of dihydrogen (H2), which is energetically inefficient and can inhibit fermentation. It would be nutritionally beneficial to incorporate accumulated H2 into propionate or butyrate production, or reductive acetogenesis. The objective of this analysis was to examine three possible physicochemical limitations to the incorporation of accumulated H2 into propionate and butyrate production, and reductive acetogenesis, in methanogenesis-inhibited ruminal batch and continuous cultures: (i) Thermodynamics; (ii) Enzyme kinetics; (iii) Substrate kinetics. Batch (N = 109) and continuous (N = 43) culture databases of experiments with at least 50% inhibition in CH4 production were used in this meta-analysis. Incorporation of accumulated H2 into propionate production and reductive acetogenesis seemed to be thermodynamically feasible but quite close to equilibrium, whereas this was less clear for butyrate. With regard to enzyme kinetics, it was speculated that hydrogenases of ruminal microorganisms may have evolved toward high-affinity and low maximal velocity to compete for traces of H2, rather than for high pressure accumulated H2. Responses so far obtained to the addition of propionate production intermediates do not allow distinguishing between thermodynamic and substrate kinetics control. PMID:26635743

  8. The Effect of Saturated Fatty Acids on Methanogenesis and Cell Viability of Methanobrevibacter ruminantium

    PubMed Central

    Zhou, Xuan; Meile, Leo; Kreuzer, Michael; Zeitz, Johanna O.

    2013-01-01

    Saturated fatty acids (SFAs) are known to suppress ruminal methanogenesis, but the underlying mechanisms are not well known. In the present study, inhibition of methane formation, cell membrane permeability (potassium efflux), and survival rate (LIVE/DEAD staining) of pure ruminal Methanobrevibacter ruminantium (DSM 1093) cell suspensions were tested for a number of SFAs. Methane production rate was not influenced by low concentrations of lauric (C12; 1 μg/mL), myristic (C14; 1 and 5 μg/mL), or palmitic (C16; 3 and 5 μg/mL) acids, while higher concentrations were inhibitory. C12 and C14 were most inhibitory. Stearic acid (C18), tested at 10–80 μg/mL and ineffective at 37°C, decreased methane production rate by half or more at 50°C and ≥50 μg/mL. Potassium efflux was triggered by SFAs (C12 = C14 > C16 > C18 = control), corroborating data on methane inhibition. Moreover, the exposure to C12 and C14 decreased cell viability to close to zero, while 40% of control cells remained alive after 24 h. Generally, tested SFAs inhibited methanogenesis, increased cell membrane permeability, and decreased survival of M. ruminantium in a dose- and time-dependent way. These results give new insights into how the methane suppressing effect of SFAs could be mediated in methanogens. PMID:23710130

  9. Transmethylation reactions during methanogenesis from acetate in Methanosarcina barkeri. [Annual report], August 1, 1991--April 1, 1993

    SciTech Connect

    Krzycki, J.A.

    1993-07-01

    Methanosarcina possesses an abundance corrinoid, which acts as enzyme prosthetic group and functions in methyl transfer reactions. When this work was initiated only two corrinoid proteins had been described from Methanosarcina: methyltransferase I, which catalyses the first step m methanogenesis from methanol; and the corrinoid/iron sulfur protein, which is the primary methyl accepting group in the cleavage of acetyl-CoA during methanogenesis from acetate. Using our technique of in vitro methylation of corrinoid proteins by radioactive methanogenic substrates we have found several novel corrinoid proteins are present in this organism which can function as methytransferases, which are methylated by growth substrate, and are apparently regulated by growth substrate.

  10. Distracted Driving

    MedlinePlus

    ... combines all three types of distraction. 3 How big is the problem? Deaths In 2013, 3,154 ... European countries. More A CDC study analyzed 2011 data on distracted driving, including talking on a cell ...

  11. Distracted driving

    MedlinePlus

    ... stay safe with a cell phone in the car. ... for Disease Control and Prevention Injury Prevention & Control. Motor Vehicle Safety. www.cdc.gov/motorvehiclesafety/distracted_driving . Accessed May ...

  12. Driving Safely

    MedlinePlus

    ... drivers’ flexibility and coordination, and reduced driving errors. S l Hand grip strengthening to help you hold on to the steering wheel l Shoulder and upper arm flexibility exercises to make ...

  13. Metabolic Erosion Primarily Through Mutation Accumulation, and Not Tradeoffs, Drives Limited Evolution of Substrate Specificity in Escherichia coli

    PubMed Central

    Leiby, Nicholas; Marx, Christopher J.

    2014-01-01

    Evolutionary adaptation to a constant environment is often accompanied by specialization and a reduction of fitness in other environments. We assayed the ability of the Lenski Escherichia coli populations to grow on a range of carbon sources after 50,000 generations of adaptation on glucose. Using direct measurements of growth rates, we demonstrated that declines in performance were much less widespread than suggested by previous results from Biolog assays of cellular respiration. Surprisingly, there were many performance increases on a variety of substrates. In addition to the now famous example of citrate, we observed several other novel gains of function for organic acids that the ancestral strain only marginally utilized. Quantitative growth data also showed that strains with a higher mutation rate exhibited significantly more declines, suggesting that most metabolic erosion was driven by mutation accumulation and not by physiological tradeoffs. These reductions in growth by mutator strains were ameliorated by growth at lower temperature, consistent with the hypothesis that this metabolic erosion is largely caused by destabilizing mutations to the associated enzymes. We further hypothesized that reductions in growth rate would be greatest for substrates used most differently from glucose, and we used flux balance analysis to formulate this question quantitatively. To our surprise, we found no significant relationship between decreases in growth and dissimilarity to glucose metabolism. Taken as a whole, these data suggest that in a single resource environment, specialization does not mainly result as an inevitable consequence of adaptive tradeoffs, but rather due to the gradual accumulation of disabling mutations in unused portions of the genome. PMID:24558347

  14. Effect of medicinal and aromatic plants on rumen fermentation, protozoa population and methanogenesis in vitro.

    PubMed

    Bhatta, R; Baruah, L; Saravanan, M; Suresh, K P; Sampath, K T

    2013-06-01

    The potential of tannins from 21 medicinal and aromatic plant leaves as antimethanogenic additives in ruminant feeds was investigated. The effect of tannin from these leaves on rumen fermentation parameters, protozoa population and methanogenesis was studied by incubating the samples [200 mg dry matter (DM)] without and with polyethylene glycol (PEG)-6000 (400 mg DM) as a tannin binder during 24-h incubation in the in vitro Hohenheim gas method. Based on the methane percentage estimated in the total gas produced, methane production in millilitre was calculated [methane volume (ml) = methane % × total gas produced (ml) in 24 h]. In the samples, crude protein and neutral detergent fibre (g/kg DM) ranged from 113 to 172 and from 352 to 444 respectively. The total phenol (TP; g/kg DM) content was highest in Terminalia chebula (274) followed by Hemigraphis colorata (71) and Sapindus laurifolia (51) respectively. In the remaining samples, it was <43 g/kg DM. Activity of tannins, as represented by the increase in gas volume on addition of PEG, ranged from 0 to 133%, with the highest being recorded in T. chebula. The per cent increase in methane on PEG addition was 0 for Ammi majus, Aristolochia indica, Cascabela thevetia, Ipomea nil and Lantana camara, illustrating that tannins present in these samples had no effect on methane concentration. The PEG addition increased the total protozoa count by >50% in A. indica and C. thevetica. One of the important findings of our study was that of the 21 samples screened, Entodinia population increased in 12 with PEG as compared to 7 where Holotricha increased, indicating higher susceptibility of Entodinia to tannin. There was no increase in the protozoa population with PEG when incubating Cardiospermum halicacabum, Clerodendrum inerme, Dioscorea floribunda, Nerium oleander and Selastras paniculatus, which strongly suggested that methane suppression recorded in these samples was not because of a defaunating effect

  15. Leachate treatment before injection into a bioreactor landfill: clogging potential reduction and benefits of using methanogenesis.

    PubMed

    Lozecznik, Stanislaw; Sparling, Richard; Oleszkiewicz, Jan A; Clark, Shawn; VanGulck, Jamie F

    2010-11-01

    In this study, an anaerobic sequencing batch reactor (ASBR) was operated with leachate from Brady Road Municipal Landfill in Winnipeg, Manitoba, Canada. Leachate was collected twice from the same cell at the landfill, during the first and 70th day of the study, and then fed into the ASBR. The ASBR was seeded at the start-up with biosolids from the anaerobic digester from Winnipeg's North End Water Pollution Control Center (NEWPCC). Due to the higher COD and VFA removal rates measured with the second batch of leachate, an increase of approximately 0.3 pH units was observed during each cycle (from pH 7.2 to 7.5). In addition, CO(2) was produced between cycles at constant temperature where a fraction of the CO(2) became dissolved, shifting the CO(2)/bicarbonate/carbonate equilibrium. Concurrent with the increase in pH and carbonate, an accumulation of fixed suspend solids (FSS) was observed within the ASBR, indicating a buildup of inorganic material over time. From it, Ca(2+) and Mg(2+) were measured within the reactor on day 140, indicating that most of the dissolved Ca(2+) was removed within cycles. There is precedence from past researches of clogging in leachate-collection systems (Rowe et al., 2004) that changes in pH and carbonate content combined with high concentrations of metals such as Ca(2+) and Mg(2+) result in carbonate mineral precipitants. A parallel study investigated this observation, indicating that leachate with high concentration of Ca(2+) under CO(2) saturation conditions can precipitate out CaCO(3) at the pH values obtained between digestion cycles. These studies presented show that methanogenesis of leachate impacts the removal of organic (COD, VFA) as well as inorganic (FSS, Ca(2+)) clog constituents from the leachate, that otherwise will accumulate inside of the recirculation pipe in bioreactor landfills. In addition, a robust methanogenesis of leachate was achieved, averaging rates of 0.35 L CH(4) produced/g COD removed which is similar to the

  16. Thermophilic sulfate reduction and methanogenesis with methanol in a high rate anaerobic reactor

    SciTech Connect

    Weijma, J.; Stams, A.J.M.; Pol, L.W.H.; Lettinga, G.

    2000-02-05

    Sulfate reduction outcompeted methanogenesis at 65 C and pH 7.5 in methanol and sulfate-fed expanded granular sludge bed reactors operated at hydraulic retention times (HRT) of 14 and 2.5 h, both under methanol-limiting and methanol-overloading conditions. After 100 and 50 days for the reactors operated at 14 and 3.5 h, respectively, sulfide production accounted for 80% of the methanol-COD consumed by the sludge. The specific methanogenic activity on methanol of the sludge from a reactor operated at HRTs of down to 3.5 h for a period of 4 months gradually decreased from 0.83 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} at the start to a value of less than 0.05 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1}, showing that the relative number of methanogens decreased and eventually became very low. By contrast, the increase of the specific sulfidogenic activity of sludge from 0.22 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} to a final value of 1.05 gCOD {sm_bullet} gVSS{sup {minus}1} {sm_bullet} day{sup {minus}1} showed that sulfate reducing bacteria were enriched. Methanol degradation by a methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanol was not important. H{sub 2}/CO{sub 2} and formate, but not acetate, were degraded to methane in the presence of vancomycin. These results indicated that methanol degradation to methane occurs via the intermediates H{sub 2}/CO{sub 2} and formate. The high and low specific methanogenic activity of sludge on H{sub 2}/CO{sub 2} and formate, respectively, indicated that the former substrate probably acts as the main electron donor for the methanogens during methanol degradation. As

  17. Incorporating H2 Dynamics and Inhibition into a Microbially Based Methanogenesis Model for Restored Wetland Sediments

    NASA Astrophysics Data System (ADS)

    Pal, David; Jaffe, Peter

    2015-04-01

    Estimates of global CH4 emissions from wetlands indicate that wetlands are the largest natural source of CH4 to the atmosphere. In this paper, we propose that there is a missing component to these models that should be addressed. CH4 is produced in wetland sediments from the microbial degradation of organic carbon through multiple fermentation steps and methanogenesis pathways. There are multiple sources of carbon for methananogenesis; in vegetated wetland sediments, microbial communities consume root exudates as a major source of organic carbon. In many methane models propionate is used as a model carbon molecule. This simple sugar is fermented into acetate and H2, acetate is transformed to methane and CO2, while the H2 and CO2 are used to form an additional CH4 molecule. The hydrogenotrophic pathway involves the equilibrium of two dissolved gases, CH4 and H2. In an effort to limit CH4 emissions from wetlands, there has been growing interest in finding ways to limit plant transport of soil gases through root systems. Changing planted species, or genetically modifying new species of plants may control this transport of soil gases. While this may decrease the direct emissions of methane, there is little understanding about how H2 dynamics may feedback into overall methane production. The results of an incubation study were combined with a new model of propionate degradation for methanogenesis that also examines other natural parameters (i.e. gas transport through plants). This presentation examines how we would expect this model to behave in a natural field setting with changing sulfate and carbon loading schemes. These changes can be controlled through new plant species and other management practices. Next, we compare the behavior of two variations of this model, with or without the incorporation of H2 interactions, with changing sulfate, carbon loading and root volatilization. Results show that while the models behave similarly there may be a discrepancy of nearly

  18. Multiple effects of trace elements on methanogenesis in a two-phase anaerobic membrane bioreactor treating starch wastewater.

    PubMed

    Yu, Dawei; Li, Chao; Wang, Lina; Zhang, Junya; Liu, Jing; Wei, Yuansong

    2016-08-01

    For enhancing anaerobic membrane bioreactor (AnMBR) treating food processing wastewater due to speed-limited methanogenesis step, multiple effects of trace element (TE) supplementation on methanogenesis of a two-phase AnMBR were firstly investigated in batch tests. TE supplementation included individual element, combination and recovery of Fe, Ni, Co, Cu and Zn supplementation. Multiple effects of TE supplementation were highest stimulated by 22.4 ± 5.6 % (TE313) for chemical oxygen demand (COD) removal, 43.1 ± 12.5 % (TE303) for specific methanogenic activity (SMA) and 13.9 ± 3.7 % (TE405) for biomass growth, respectively, although only 7.5 ± 0.6 % (TE106) for methane production. Dosage of TEs played a critical role in methane production, COD removal and biomass growth of the AnMBR's methanogenesis. Low dosages of TE supplementation improved the COD removal and slightly stimulated the COD bioconverting to methane and biomass, but their specific methanation activities were inhibited in the initial rapid methanogenesis stage. Several methanation functional species were increased in abundance like Methanosarcina and Methanoculleus. PMID:26879957

  19. Rheological behavior of physicochemical sludges during methanogenesis suppression and hydrogen production at different organic loading rates.

    PubMed

    Méndez-Contreras, Juan Manuel; López-Escobar, Luis A; Martínez-Hernández, Sergio; Cantú-Lozano, Denis; Ortiz-Ceballos, Angel I

    2016-06-01

    This study investigated the rheological behavior of raw physicochemical sludges and sludges that were digested at different organic loading rates (OLRs) (1, 5, 10 and 15 gVS L(-1) d(-1)) during methanogenesis suppression to produce hydrogen anaerobically. The Herschel-Bulkley model was used to describe the rheology of these sludges with specific properties. The results indicate that the Herschel-Bulkley model adequately described the rheology ([Formula: see text] ≠ 0) of this type of fluids (R(2) > 0.98). In addition, the raw physicochemical sludges and those that were digested at different OLRs had dilatant behaviors (n > 1), which increased with increasing OLR. These results identified the apparent viscosity, yield stress, pH and OLR conditions that allow for the production and suppression of methane, as well as the conditions that guarantee the production of hydrogen. PMID:26943338

  20. Method for assessing the impact of emission gasses on physiology and productivity in biological methanogenesis.

    PubMed

    Seifert, A H; Rittmann, S; Bernacchi, S; Herwig, C

    2013-05-01

    This contribution presents a method for quantification of the impact of emission gasses on the methane production with hydrogenotrophic methanogenic archaea. The developed method allows a robust quantification of the influence of real gasses on the volumetric productivity of methanogenic cultures by uncoupling physiological and mass transfer effects. This is achieved over reference experiments with pure H2 and CO2, simulating the mass transfer influence of the non-convertible side components by addition of N2 to the reactant stream. Furthermore, this method was used to examine the performance of Methanothermobacter marburgensis on different emission gasses. None of the present side components had a negative effect on the volumetric methane production rate. The presented method showed to be ready to use as a generic tool for feasibility studies and quantification of the physiological impact regarding the use of exhaust gasses as reactant gas for the biological methanogenesis. PMID:23582218

  1. Methanogenesis in Big Soda Lake, Nevada: an Alkaline, Moderately Hypersaline Desert Lake

    PubMed Central

    Oremland, Ronald S.; Marsh, Lorraine; DesMarais, David J.

    1982-01-01

    Incubated sediment slurries from Big Soda Lake, Nevada, produced significant levels of CH4, and production was inhibited by 2-bromoethanesulfonic acid and by autoclaving. Methane production was stimulated by methanol, trimethylamine, and, to a lesser extent, methionine. Surprisingly, hydrogen, acetate, and formate amendments provided only slight or no stimulation of methanogenesis. Methane production by sediment slurries had a pH optimum of 9.7. A methanol-grown enrichment culture containing a small, epifluorescent coccus as the predominant organism was recovered from sediments. The enrichment grew best when FeS or autoclaved sediment particles were included in the media, had a pH optimum of 9.7, and produced 14CH4 from 14CH3OH. The methane formed by methanolgrown enrichment cultures was depleted in 13C by 72 to 77‰ relative to the methanol. PMID:16345952

  2. Anaerobic mineralization of indigenous organic matters and methanogenesis in tropical wetland soils

    SciTech Connect

    Miyajima, Toshihiro; Wada, Eitaro; Hanba, Yuko T.; Vijarnsorn, P.

    1997-09-01

    Tropical wetlands are one of the largest natural sources in the global methane budget due to high biological activities and the anaerobiosis in soil. We studied mineralization and gas production during the early stage of anaerobic decomposition of indigenous organic matters in soils of Narathiwat, southern Thailand, to clarify the significance of the substrate quality in controlling decomposition and methanogenesis in some different tropical wetland soils. The optimal temperature of decomposition was around 35{degrees}C, while methanogenesis did not proceed at 45{degrees}C. During the first 50 days of anaerobic incubation, 5 {approximately} 63% (carbon basis) of indigeneous plant leaves were mineralized. The mineralization rate was strongly and negatively correlated with the lignin and/or fiber contents, but not the C/N ratio, of the substrate plant materials. Difference in {delta}{sup 13}C between the substrate, indicating that H{sub 2} as opposed to acetate becomes a more important metabolic intermediate in the anaerobic food web when the decomposition rate is limited by substrate recalcitrance. Thus, the CH{sub 4} isotope signature may be used to evaluate the importance of new vs. old organic matter as CH{sub 4} isotope signature may be used to evaluate the importance of new vs. old organic matter as CH{sub 4} source in natural soils. The mineralization rate was higher, and the isotopic difference between the substrate and CH{sub 4} was smaller when plant materials were incubated with sulfate-contaminated soils than with native peat soils. The isotopic difference between the substrate and CH{sub 4} was significantly different between native peat soils. Results of a tracer experiment using {sup 13}C-labeled substrates indicated that these differences could be ascribed to difference in the mode of acetate metabolism between soils. 49 refs., 8 figs., 7 tabs.

  3. Modeling the Interaction of H2 on Root Exudate Degradation and Methanogenesis in Wetland Sediments

    NASA Astrophysics Data System (ADS)

    Pal, D. S.; Jaffe, P. R.

    2014-12-01

    CH4 is produced in wetland sediments from the microbial degradation of organic carbon through multiple fermentation steps and methanogenesis pathways. There are many potential sources of carbon for methananogenesis; in vegetated wetland sediments, microbial communities consume root exudates as a major source of organic carbon. In many methane models propionate is used as a model carbon molecule. This simple sugar is fermented into acetate and H2, acetate is transformed to methane and CO2 while the H2 and CO2 is synthesized to form an additional CH4 molecule. The hydrogenotrophic pathway involves the equilibrium of two dissolved gases, CH4 and H2. In an effort to limit CH4 emissions from wetlands, there has been growing interest in finding ways to limit plant transport of soil gases through root systems. While this may decrease the direct emissions of methane, there is little understanding about how H2 dynamics may feedback into overall methane production. Since H2 is used in methane production and produced in propionate fermentation, increased subsurface H2 concentrations can simultaneously inhibit propionate fermentation and acetate production and enhance hydrogenotrophic methanogenesis. For this study, we incubated soil samples from vegetated wetland sediments with propionate or acetate and four different hydrogen concentrations. The headspaces from these incubations were simultaneously analyzed for H2 and CH4 at multiple time points over two months. The comparison of methane production between different hydrogen concentrations and different carbon sources can indicate which process is most affected by increased hydrogen concentrations. The results from this study were combined with a newly formulated steady-state model of propionate degradation and formation of methane, that also accounts for the venting off both gases via plants. The resulting model indicates how methane production and emissions would be affected by plant volatilization.

  4. Effects of Coconut Materials on In vitro Ruminal Methanogenesis and Fermentation Characteristics

    PubMed Central

    Kim, E. T.; Park, C. G.; Lim, D. H.; Kwon, E. G.; Ki, K. S.; Kim, S. B.; Moon, Y. H.; Shin, N. H.; Lee, S. S.

    2014-01-01

    The objective of this study was to evaluate the in vitro effects of coconut materials on ruminal methanogenesis and fermentation characteristics, in particular their effectiveness for mitigating ruminal methanogenesis. Fistulated Holstein cows were used as the donor of rumen fluid. Coconut materials were added to an in vitro fermentation incubated with rumen fluid-buffer mixture and timothy substrate for 24 h incubation. Total gas production, gas profiles, total volatile fatty acids (tVFAs) and the ruminal methanogens diversity were measured. Although gas profiles in added coconut oil and coconut powder were not significantly different, in vitro ruminal methane production was decreased with the level of reduction between 15% and 19% as compared to control, respectively. Coconut oil and coconut powder also inhibited gas production. The tVFAs concentration was increased by coconut materials, but was not affected significantly as compared to control. Acetate concentration was significantly lower (p<0.05), while propionate was significantly higher (p<0.05) by addition of the coconut materials than that of the control. The acetate:propionate ratio was significantly lowered with addition of coconut oil and coconut powder (p<0.05). The methanogens and ciliate-associated methanogens in all added coconut materials were shown to decrease as compared with control. This study showed that ciliate-associated methanogens diversity was reduced by more than 50% in both coconut oil and coconut powder treatments. In conclusion, these results indicate that coconut powder is a potential agent for decreasing in vitro ruminal methane production and as effective as coconut oil. PMID:25358365

  5. The kinetics of process dependent ammonia inhibition of methanogenesis from acetic acid.

    PubMed

    Wilson, Christopher Allen; Novak, John; Takacs, Imre; Wett, Bernhard; Murthy, Sudhir

    2012-12-01

    Advanced anaerobic digestion processes aimed at improving the methanization of sewage sludge may be potentially impaired by the production of inhibitory compounds (e.g. free ammonia). The result of methanogenic inhibition is relatively high effluent concentrations of acetic acid and other soluble organics, as well as reduced methane yields. An extreme example of such an advanced process is the thermal hydrolytic pretreatment of sludge prior to high solids digestion (THD). Compared to a conventional mesophilic anaerobic digestion process (MAD), THD operates in a state of constant inhibition driven by high free ammonia concentrations, and elevated pH values. As such, previous investigations of the kinetics of methanogenesis from acetic acid under uninhibited conditions do not necessarily apply well to the modeling of extreme processes such as THD. By conducting batch ammonia toxicity assays using biomass from THD and MAD reactors, we compared the response of these communities over a broad range of ammonia inhibition. For both processes, increased inhibitor concentrations resulted in a reduction of biomass growth rate (r(max) = μ(max)∙X) and a resulting decrease in the substrate half saturation coefficient (K(S)). These two parameters exhibited a high degree of correlation, suggesting that for a constant transport limited system, the K(S) was mostly a linear function of the growth rate. After correcting for reactor pH and temperature, we found that the THD and MAD biomass were both able to perform methanogenesis from acetate at high free ammonia concentrations (equivalent to 3-5 g/L total ammonia nitrogen), albeit at less than 30% of their respective maximum rates. The reduction in methane production was slightly less pronounced for the THD biomass than for MAD, suggesting that the long term exposure to ammonia had selected for a methanogenic pathway less dependent on those organisms most sensitive to ammonia inhibition (i.e. aceticlastic methanogens). PMID

  6. Salinity and Temperature Constraints on Microbial Methanogenesis in the Lei-Gong-Huo Mud Volcano of Eastern Taiwan

    NASA Astrophysics Data System (ADS)

    Sun, W.; Lin, L.; Wang, P.

    2012-12-01

    Terrestrial mud volcano is thought to be one of the most important natural sources of methane emission. Previous studies have shown that methane cycling in terrestrial mud volcanoes involves a complex reaction network driven by the interactions between subsurface and surface abiotic and microbial processes. In situ methanogenesis appears to produce methane at quantities exceeding those of deeply-sourced thermogenic methane and the capacities of anaerobic methanotrophy at shallow depth levels, thereby contributing significantly to the methane emission. Various degrees of evaporation at surface also lead to the enhancement of chloride concentrations in pore water, favoring the proliferation of halo-tolerant and/or halophilic methanogens. The goal of this study is to investigate the extent of methanogenesis in terrestrial mud volcanoes by incubating mud slurries with various precursors (H2/CO2, acetate, methanol, and methylamine) at different salinities (up to 2000 mM) and temperatures (up to 50 oC). Methane concentrations were monitored through time and molecular analyses were applied to investigate the changes of methanogenic communities. Methanogenesis was stimulated by any investigated precursor at room temperature. However, the methanogenic response to salinity varied. Of the investigated precursors, H2/CO2 and methyl-compounds (methanol and methylamine) stimulated methanogenesis at all investigated salinities. The rates and yields of hydrogen- and methyl-utilizing methanogenesis declined significantly at salinities greater than 1500 mM. Acetate-utilizing methanogenesis proceeded at salinities less than 700 mM. At 40 oC, methanogenesis was stimulated by all investigated precursors at the in situ salinity (~400 mM). At 50 oC, only H2-utilizing methanogenesis was stimulated. Analyses of terminal restriction fragment length polymorphism (TRFLP) for 16S rRNA genes revealed various patterns upon different precursors and salinities. The TRFLP results combined with

  7. Rock Magnetic Study in the Methanogenesis Zone, Site U1437, IODP Exp 350, Izu Rear Arc

    NASA Astrophysics Data System (ADS)

    Kars, M. A. C.; Musgrave, R. J.; Kodama, K.; Jonas, A. S.

    2015-12-01

    In 2014, IODP Expedition 350 drilled a 1806.5 m deep hole at Site U1437 in the Izu Bonin rear arc. The Site presents an unusual deep methanogenesis zone because of a release of sulfate below the sulfate reduction zone (27-83 mbsf) which may buffer methanogenesis by anaerobic methanogens. Methane abundance gradually increases with depth, with significant abundance at ~750-1459 mbsf with a maximum value at 920 mbsf. The rock magnetic study carried out in Hole U1437D from ~775 to ~1000 mbsf shows a drastic change of the magnetic properties at ~850 mbsf coincidently with a stronger release of methane from < 60 ppm at 841 mbsf to ~300 ppm at 854 mbsf. That also corresponds to a depth interval where no core was recovered (~846-854 mbsf). For the sake of clarity, we call hereafter zone A the depth interval above this non-recovered interval (775-846 mbsf) and zone B the interval below (854-1000 mbsf). Both belong to the same lithostratigraphic unit composed of tuffaceous mudstones intercalated with volcanoclastics. In the zone A, NRM, magnetic susceptibility, ARM, SIRM, HIRM display high values. In the zone B, these parameters show much lower values of one order of magnitude less, except for the interval 936-950 mbsf that corresponds to a local maximum (but still lower values than the zone A). Besides, the rock magnetic parameters for grain size and coercivity, such as ARM/χ, S-ratio and Bcr do not show any variations throughout the entire studied interval, although S-ratio displays slightly lower values from ~850 to ~930 mbsf. Grains are low coercivity pseudo-single domain sized. According to the present data, two preliminary hypotheses can be proposed to explain the observations. 1) The non-recovered interval between the zones A and B can be caused by the presence of a sedimentary hiatus and/or a fault, which may be consistent with the observed change in sedimentation rate. 2) No hiatus in the sedimentation. The changes in the magnetic properties can be explained by a

  8. The impacts of drying and rewetting cycles on potential methanogenesis in wetland soils

    NASA Astrophysics Data System (ADS)

    Kannenberg, S.; Ludwig, S.; Nelson, L.; Rich, H.; Spawn, S.; Porterfield, J.; Schade, J. D.

    2012-12-01

    Wetlands are currently the world's largest natural emitter of methane, a greenhouse gas that is over 20 times more effective at trapping heat than carbon dioxide. The magnitude of expansion and contraction of wetlands is likely to increase in response to greater severity of precipitation and drought events predicted by climate change models. Increased severity of precipitation and drought events will result in greater variability in size and ephemerality of wetlands. One possible outcome of these size fluctuations is the increase in the anoxic areas preferred by methanogens. Thus, it is becoming increasingly important to discover how production of methane may change as conditions vary. Our objective was to investigate how wetland dynamics, including variability in size and ephemerality, affect methanogenesis and influence the underlying microbial community. We sampled soil from three wetlands of differing ephemerality on the St. Olaf Natural Lands. We measured water and KCl-extractable NO3 and NH4 and used chloroform-fumigation direct-extraction (CFDE) to estimate microbial biomass in each soil sample. Subsamples of each core were incubated in bottles under anoxic conditions in the dark to measure rate of methane production. Bottles were incubated for 9 weeks and headspace samples were collected after 2, 24, and 48 hours and 1 week, and then weekly thereafter. Headspace samples were analyzed for CH4 to calculate rates of methanogenesis. The rate of methane production over the first 48 hours was positively correlated with soil moisture, and negatively correlated with nitrate levels. At the end of the incubation period, methane production was not related to moisture and nitrate, and was positively correlated with soil organic matter. In addition, we observed a lag time before the onset of significant methane flux, followed by a rapid increase in concentration. This lag time was shorter in wet soils than in dry soils. These data suggest that wet, low-nitrate soils

  9. Stable Carbon Isotope Fractionation by Methanosarcina barkeri during Methanogenesis from Acetate, Methanol, or Carbon Dioxide-Hydrogen

    PubMed Central

    Krzycki, J. A.; Kenealy, W. R.; DeNiro, M. J.; Zeikus, J. G.

    1987-01-01

    Methanosarcina barkeri was cultured on methanol, H2-CO2, and acetate, and the 13C/12C ratios of the substrates and the methane produced from them were determined. The discrimination against 13C in methane relative to substrate decreased in the order methanol > CO2 > acetate. The isotopic fractionation for methane derived from acetate was only one-third of that observed with methanol as the substrate. The data presented indicate that the last enzyme of methanogenesis, methylreductase, is not the primary site of isotopic discrimination during methanogenesis from methanol or CO2. These results also support biogeochemical interpretations that gas produced in environments in which acetate is the primary methane precursor will have higher 13C/12C ratios than those from environments where other substrates predominate. PMID:16347476

  10. Stoichiometry and temperature sensitivity of methanogenesis and CO 2 production from saturated polygonal tundra in Barrow, Alaska

    DOE PAGESBeta

    Roy Chowdhury, Taniya; Herndon, Elizabeth M.; Phelps, Tommy J.; Elias, Dwayne A.; Gu, Baohua; Liang, Liyuan; Wullschleger, Stan D.; Graham, David E.

    2014-11-26

    Arctic permafrost ecosystems store ~50% of global belowground carbon (C) that is vulnerable to increased microbial degradation with warmer active layer temperatures and thawing of the near surface permafrost. We used anoxic laboratory incubations to estimate anaerobic CO2 production and methanogenesis in active layer (organic and mineral soil horizons) and permafrost samples from center, ridge and trough positions of water-saturated low-centered polygon in Barrow Environmental Observatory, Barrow AK, USA. Methane (CH4) and CO2 production rates and concentrations were determined at 2, +4, or +8 C for 60 day incubation period. Temporal dynamics of CO2 production and methanogenesis at 2 Cmore » showed evidence of fundamentally different mechanisms of substrate limitation and inhibited microbial growth at soil water freezing points compared to warmer temperatures. Nonlinear regression better modeled the initial rates and estimates of Q10 values for CO2 that showed higher sensitivity in the organic-rich soils of polygon center and trough than the relatively drier ridge soils. Methanogenesis generally exhibited a lag phase in the mineral soils that was significantly longer at 2 C in all horizons. Such discontinuity in CH4 production between 2 C and the elevated temperatures (+4 and +8 C) indicated the insufficient representation of methanogenesis on the basis of Q10 values estimated from both linear and nonlinear models. Production rates for both CH4 and CO2 were substantially higher in organic horizons (20% to 40% wt. C) at all temperatures relative to mineral horizons (<20% wt. C). Permafrost horizon (~12% wt. C) produced ~5-fold less CO2 than the active layer and negligible CH4. High concentrations of initial exchangeable Fe(II) and increasing accumulation rates signified the role of iron as terminal electron acceptors for anaerobic C degradation in the mineral horizons.« less

  11. Lovastatin lactone may improve irritable bowel syndrome with constipation (IBS-C) by inhibiting enzymes in the archaeal methanogenesis pathway

    PubMed Central

    Muskal, Steven M.; Sliman, Joe; Kokai-Kun, John; Pimentel, Mark; Wacher, Vince; Gottlieb, Klaus

    2016-01-01

    Methane produced by the methanoarchaeon Methanobrevibacter smithii ( M. smithii) has been linked to constipation, irritable bowel syndrome with constipation (IBS-C), and obesity. Lovastatin, which demonstrates a cholesterol-lowering effect by the inhibition of HMG-CoA reductase, may also have an anti-methanogenesis effect through direct inhibition of enzymes in the archaeal methanogenesis pathway. We conducted protein-ligand docking experiments to evaluate this possibility. Results are consistent with recent clinical findings. METHODS: F420-dependent methylenetetrahydromethanopterin dehydrogenase ( mtd), a key methanogenesis enzyme was modeled for two different methanogenic archaea: M. smithii and Methanopyrus kandleri. Once protein models were developed, ligand-binding sites were identified. Multiple ligands and their respective protonation, isomeric and tautomeric representations were docked into each site, including F420-coenzyme (natural ligand), lactone and β-hydroxyacid forms of lovastatin and simvastatin, and other co-complexed ligands found in related crystal structures. RESULTS: 1) Generally, for each modeled site the lactone form of the statins had more favorable site interactions compared to F420; 2) The statin lactone forms generally had the most favorable docking scores, even relative to the native template PDB ligands; and 3) The statin β-hydroxyacid forms had less favorable docking scores, typically scoring in the middle with some of the F420 tautomeric forms. Consistent with these computational results were those from a recent phase II clinical trial ( NCT02495623) with a proprietary, modified-release lovastatin-lactone (SYN-010) in patients with IBS-C, which showed a reduction in symptoms and breath methane levels, compared to placebo. CONCLUSION: The lactone form of lovastatin exhibits preferential binding over the native-F420 coenzyme ligand in silico and thus could inhibit the activity of the key M. smithii methanogenesis enzyme mtd in vivo

  12. Stoichiometry and temperature sensitivity of methanogenesis and CO 2 production from saturated polygonal tundra in Barrow, Alaska

    SciTech Connect

    Roy Chowdhury, Taniya; Herndon, Elizabeth M.; Phelps, Tommy J.; Elias, Dwayne A.; Gu, Baohua; Liang, Liyuan; Wullschleger, Stan D.; Graham, David E.

    2014-11-26

    Arctic permafrost ecosystems store ~50% of global belowground carbon (C) that is vulnerable to increased microbial degradation with warmer active layer temperatures and thawing of the near surface permafrost. We used anoxic laboratory incubations to estimate anaerobic CO2 production and methanogenesis in active layer (organic and mineral soil horizons) and permafrost samples from center, ridge and trough positions of water-saturated low-centered polygon in Barrow Environmental Observatory, Barrow AK, USA. Methane (CH4) and CO2 production rates and concentrations were determined at 2, +4, or +8 C for 60 day incubation period. Temporal dynamics of CO2 production and methanogenesis at 2 C showed evidence of fundamentally different mechanisms of substrate limitation and inhibited microbial growth at soil water freezing points compared to warmer temperatures. Nonlinear regression better modeled the initial rates and estimates of Q10 values for CO2 that showed higher sensitivity in the organic-rich soils of polygon center and trough than the relatively drier ridge soils. Methanogenesis generally exhibited a lag phase in the mineral soils that was significantly longer at 2 C in all horizons. Such discontinuity in CH4 production between 2 C and the elevated temperatures (+4 and +8 C) indicated the insufficient representation of methanogenesis on the basis of Q10 values estimated from both linear and nonlinear models. Production rates for both CH4 and CO2 were substantially higher in organic horizons (20% to 40% wt. C) at all temperatures relative to mineral horizons (<20% wt. C). Permafrost horizon (~12% wt. C) produced ~5-fold less CO2 than the active layer and negligible CH4. High concentrations of initial exchangeable Fe(II) and increasing accumulation rates signified the role of iron as terminal electron acceptors for anaerobic C degradation in the mineral horizons.

  13. Stoichiometry and temperature sensitivity of methanogenesis and CO2 production from saturated polygonal tundra in Barrow, Alaska.

    PubMed

    Roy Chowdhury, Taniya; Herndon, Elizabeth M; Phelps, Tommy J; Elias, Dwayne A; Gu, Baohua; Liang, Liyuan; Wullschleger, Stan D; Graham, David E

    2015-02-01

    Arctic permafrost ecosystems store ~50% of global belowground carbon (C) that is vulnerable to increased microbial degradation with warmer active layer temperatures and thawing of the near surface permafrost. We used anoxic laboratory incubations to estimate anaerobic CO2 production and methanogenesis in active layer (organic and mineral soil horizons) and permafrost samples from center, ridge and trough positions of water-saturated low-centered polygon in Barrow Environmental Observatory, Barrow AK, USA. Methane (CH4 ) and CO2 production rates and concentrations were determined at -2, +4, or +8 °C for 60 day incubation period. Temporal dynamics of CO2 production and methanogenesis at -2 °C showed evidence of fundamentally different mechanisms of substrate limitation and inhibited microbial growth at soil water freezing points compared to warmer temperatures. Nonlinear regression better modeled the initial rates and estimates of Q10 values for CO2 that showed higher sensitivity in the organic-rich soils of polygon center and trough than the relatively drier ridge soils. Methanogenesis generally exhibited a lag phase in the mineral soils that was significantly longer at -2 °C in all horizons. Such discontinuity in CH4 production between -2 °C and the elevated temperatures (+4 and +8 °C) indicated the insufficient representation of methanogenesis on the basis of Q10 values estimated from both linear and nonlinear models. Production rates for both CH4 and CO2 were substantially higher in organic horizons (20% to 40% wt. C) at all temperatures relative to mineral horizons (<20% wt. C). Permafrost horizon (~12% wt. C) produced ~5-fold less CO2 than the active layer and negligible CH4 . High concentrations of initial exchangeable Fe(II) and increasing accumulation rates signified the role of iron as terminal electron acceptors for anaerobic C degradation in the mineral horizons. PMID:25308891

  14. Stoichiometry and temperature sensitivity of methanogenesis and CO2 production from saturated polygonal tundra in Barrow, Alaska

    DOE PAGESBeta

    Roy Chowdhury, Taniya; Herndon, Elizabeth M; Phelps, Tommy Joe; Elias, Dwayne A; Gu, Baohua; Liang, Liyuan; Wullschleger, Stan D; Graham, David E

    2015-01-01

    Arctic permafrost ecosystems store ~50% of global belowground carbon (C) that is vulnerable to increased microbial degradation with warmer active layer temperatures and thawing of the near surface permafrost. We used anoxic laboratory incubations to estimate anaerobic CO2 production and methanogenesis in active layer (organic and mineral soil horizons) and permafrost samples from center, ridge and trough positions of water-saturated low-centered polygon in Barrow Environmental Observatory, Barrow AK, USA. Methane (CH4) and CO2 production rates and concentrations were determined at 2, +4, or +8 C for 60 day incubation period. Temporal dynamics of CO2 production and methanogenesis at 2 Cmore » showed evidence of fundamentally different mechanisms of substrate limitation and inhibited microbial growth at soil water freezing points compared to warmer temperatures. Nonlinear regression better modeled the initial rates and estimates of Q10 values for CO2 that showed higher sensitivity in the organic-rich soils of polygon center and trough than the relatively drier ridge soils. Methanogenesis generally exhibited a lag phase in the mineral soils that was significantly longer at 2 C in all horizons. Such discontinuity in CH4 production between 2 C and the elevated temperatures (+4 and +8 C) indicated the insufficient representation of methanogenesis on the basis of Q10 values estimated from both linear and nonlinear models. Production rates for both CH4 and CO2 were substantially higher in organic horizons (20% to 40% wt. C) at all temperatures relative to mineral horizons (<20% wt. C). Permafrost horizon (~12% wt. C) produced ~5-fold less CO2 than the active layer and negligible CH4. High concentrations of initial exchangeable Fe(II) and increasing accumulation rates signified the role of iron as terminal electron acceptors for anaerobic C degradation in the mineral horizons.« less

  15. Phosphoproteomic analysis of Methanohalophilus portucalensis FDF1(T) identified the role of protein phosphorylation in methanogenesis and osmoregulation.

    PubMed

    Wu, Wan-Ling; Lai, Shu-Jung; Yang, Jhih-Tian; Chern, Jeffy; Liang, Suh-Yuen; Chou, Chi-Chi; Kuo, Chih-Horng; Lai, Mei-Chin; Wu, Shih-Hsiung

    2016-01-01

    Methanogens have gained much attention for their metabolic product, methane, which could be an energy substitute but also contributes to the greenhouse effect. One factor that controls methane emission, reversible protein phosphorylation, is a crucial signaling switch, and phosphoproteomics has become a powerful tool for large-scale surveying. Here, we conducted the first phosphorylation-mediated regulation study in halophilic Methanohalophilus portucalensis FDF1(T), a model strain for studying stress response mechanisms in osmoadaptation. A shotgun approach and MS-based analysis identified 149 unique phosphoproteins. Among them, 26% participated in methanogenesis and osmolytes biosynthesis pathways. Of note, we uncovered that protein phosphorylation might be a crucial factor to modulate the pyrrolysine (Pyl) incorporation and Pyl-mediated methylotrophic methanogenesis. Furthermore, heterologous expression of glycine sarcosine N-methyltransferase (GSMT) mutant derivatives in the osmosensitive Escherichia coli MKH13 revealed that the nonphosphorylated T68A mutant resulted in increased salt tolerance. In contrast, mimic phosphorylated mutant T68D proved defective in both enzymatic activity and salinity tolerance for growth. Our study provides new insights into phosphorylation modification as a crucial role of both methanogenesis and osmoadaptation in methanoarchaea, promoting biogas production or reducing future methane emission in response to global warming and climate change. PMID:27357474

  16. Phosphoproteomic analysis of Methanohalophilus portucalensis FDF1T identified the role of protein phosphorylation in methanogenesis and osmoregulation

    PubMed Central

    Wu, Wan-Ling; Lai, Shu-Jung; Yang, Jhih-Tian; Chern, Jeffy; Liang, Suh-Yuen; Chou, Chi-Chi; Kuo, Chih-Horng; Lai, Mei-Chin; Wu, Shih-Hsiung

    2016-01-01

    Methanogens have gained much attention for their metabolic product, methane, which could be an energy substitute but also contributes to the greenhouse effect. One factor that controls methane emission, reversible protein phosphorylation, is a crucial signaling switch, and phosphoproteomics has become a powerful tool for large-scale surveying. Here, we conducted the first phosphorylation-mediated regulation study in halophilic Methanohalophilus portucalensis FDF1T, a model strain for studying stress response mechanisms in osmoadaptation. A shotgun approach and MS-based analysis identified 149 unique phosphoproteins. Among them, 26% participated in methanogenesis and osmolytes biosynthesis pathways. Of note, we uncovered that protein phosphorylation might be a crucial factor to modulate the pyrrolysine (Pyl) incorporation and Pyl-mediated methylotrophic methanogenesis. Furthermore, heterologous expression of glycine sarcosine N-methyltransferase (GSMT) mutant derivatives in the osmosensitive Escherichia coli MKH13 revealed that the nonphosphorylated T68A mutant resulted in increased salt tolerance. In contrast, mimic phosphorylated mutant T68D proved defective in both enzymatic activity and salinity tolerance for growth. Our study provides new insights into phosphorylation modification as a crucial role of both methanogenesis and osmoadaptation in methanoarchaea, promoting biogas production or reducing future methane emission in response to global warming and climate change. PMID:27357474

  17. The integration of methanogenesis with denitrification and anaerobic ammonium oxidation in an expanded granular sludge bed reactor.

    PubMed

    Zang, Dai-Jun

    2003-05-01

    The integration of methanogenesis with denitrification and anaerobic ammonium oxidation (ANAMMOX) was studied in an expanded granular sludge bed (EGSB) reactor in this work. Experimental results from the continuous treatment of wastewater with nitrite and ammonium, which lasted for 107 days, demonstrated that wastewater with high nitrite and ammonium could be anaerobically treated in an expanded granular sludge bed reactor. More than 91% to 97% of COD were removed at up to about 3.9 g COD/(L x d) of COD volumetric loading rate. More than 97% to 100% of nitrite was denitrified at up to about 0.8 g NO2(-) -N/(L x d), which is 16 times higher than that in a conventional activated sludge system with nitrification/denitrification (0.05 gN/(L x d)). No dissimilatory reduction of nitrite to ammonium occurred in the process. However, maximum of about 40% ammonium was found to be lost. Batch tests of 15 days with sludge from the reactor showed that 100% of nitrite was denitrified completely, and about 3% of ammonium was removed when only ammonium (34.3 mg/L) and nitrite (34.3 mg/ L) were added into the sludge suspension medium. Furthermore, about 15% of ammonium amounts were lost with organic COD addition. It suggested that the methanogenesis in the system could enhance ANAMMOX because of intermediate hydrogen produced during methanogenesis. PMID:12938997

  18. Sequential generation of hydrogen and methane from glutamic acid through combined photo-fermentation and methanogenesis.

    PubMed

    Xia, Ao; Cheng, Jun; Lin, Richen; Liu, Jianzhong; Zhou, Junhu; Cen, Kefa

    2013-03-01

    Glutamic acid can hardly produce hydrogen via dark- or photo-fermentation without pretreatment. In this study, a novel process of acidogenic pretreatment with bacteria and zeolite treatment for NH4(+) removal was proposed to use glutamic acid as feedstock in photo-fermentation for efficient hydrogen production. Glutamic acid pretreated with acidogenic bacteria produces soluble metabolite products. After zeolite treatment, the acidulated solution, which mainly contains acetate, butyrate, and NH4(+), shows a decrease in NH4(+) concentration from 36.7mM to 3.2mM (NH4(+) removal efficiency of 91.1%). After NH4(+) removal, the treated solution is incubated with photosynthetic bacteria, exhibiting a maximum hydrogen yield of 292.9mL/g(-glutamic acid) during photo-fermentation. The residual solution from photo-fermentation is reused by methanogenic bacteria to produce a maximum methane yield of 102.7mL/g. The heating value conversion efficiency from glutamic acid to gas fuel significantly increases from 18.9% during photo-fermentation to 40.9% in the combined photo-fermentation and methanogenesis process. PMID:23347921

  19. Eubacteria and Archaea community of simultaneous methanogenesis and denitrification granular sludge.

    PubMed

    Sun, Yujiao; Zuo, Jiane; Chen, Lili; Wang, Yong

    2008-01-01

    Based on the successful performance of a lab-scale upflow anaerobic sludge blanket (UASB) reactor with the capacity of simultaneous methanogenesis and denitrification (SMD), the specific phylogenetic groups and community structure of microbes in the SMD granule in the UASB reactor were investigated by the construction of the Eubacteria and Archaea 16S rDNA clone libraries, fragment length polymorphism, and sequence blast. Real time quantitative-polymerase chain reaction (RTQ-PCR) technique was used to quantify the contents of Eubacteria and Archaea in the SMD granule. The contents of some special predominant methanogens were also investigated. The results indicated that the Methanosaeta and Methanobacteria were the predominant methanogens in all Archaea in the SMD granule, with contents of 71.59% and 22.73% in all 88 random Archaea clones, respectively. The diversity of Eubacteria was much more complex than that of Archaea. The low GC positive gram bacteria and epsilon-Protebacteria were the main predominant Eubacteria species in SMD granule, their contents were 49.62% and 12.03% in all 133 random Eubacteria clones respectively. The results of RTQ-PCR indicated that the content of Archaea was less than Eubacteria, the Archaea content in total microorganisms in SMD granule was about 27.6%. PMID:18575118

  20. Lovastatin-Enriched Rice Straw Enhances Biomass Quality and Suppresses Ruminal Methanogenesis

    PubMed Central

    Faseleh Jahromi, Mohammad; Liang, Juan Boo; Mohamad, Rosfarizan; Goh, Yong Meng; Shokryazdan, Parisa; Ho, Yin Wan

    2013-01-01

    The primary objective of this study was to test the hypothesis that solid state fermentation (SSF) of agro-biomass (using rice straw as model); besides, breaking down its lignocellulose content to improve its nutritive values also produces lovastatin which could be used to suppress methanogenesis in the rumen ecosystem. Fermented rice straw (FRS) containing lovastatin after fermentation with Aspergillus terreus was used as substrate for growth study of rumen microorganisms using in vitro gas production method. In the first experiment, the extract from the FRS (FRSE) which contained lovastatin was evaluated for its efficacy for reduction in methane (CH4) production, microbial population, and activity in the rumen fluid. FRSE reduced total gas and CH4 productions (P < 0.01). It also reduced (P < 0.01) total methanogens population and increased the cellulolytic bacteria including Ruminococcus albus, Fibrobacter succinogenes (P < 0.01), and Ruminococcus flavefaciens (P < 0.05). Similarly, FRS reduced total gas and CH4 productions, methanogens population, but increased in vitro dry mater digestibility compared to the non-fermented rice straw. Lovastatin in the FRSE and the FRS significantly increased the expression of HMG-CoA reductase gene that produces HMG-CoA reductase, a key enzyme for cell membrane production in methanogenic Archaea. PMID:23484116

  1. Effects of Medicinal Herb Extracts on In vitro Ruminal Methanogenesis, Microbe Diversity and Fermentation System

    PubMed Central

    Kim, Eun Tae; Hwang, Hee Soon; Lee, Sang Min; Lee, Shin Ja; Lee, Il Dong; Lee, Su Kyoung; Oh, Da Som; Lim, Jung Hwa; Yoon, Ho Baek; Jeong, Ha Yeon; Im, Seok Ki; Lee, Sung Sill

    2016-01-01

    This study was aimed to evaluate the in vitro effects of medicinal herb extracts (MHEs) on ruminal fermentation characteristics and the inhibition of protozoa to reduce methane production in the rumen. A fistulated Hanwoo was used as a donor of rumen fluid. The MHEs (T1, Veratrum patulum; T2, Iris ensata var. spontanea; T3, Arisaema ringens; T4, Carduus crispus; T5, Pueraria thunbergiana) were added to the in vitro fermentation bottles containing the rumen fluid and medium. Total volatile fatty acid (tVFA), total gas production, gas profiles, and the ruminal microbe communities were measured. The tVFA concentration was increased or decreased as compared to the control, and there was a significant (p<0.05) difference after 24 h incubation. pH and ruminal disappearance of dry matter did not show significant difference. As the in vitro ruminal fermentation progressed, total gas production in added MHEs was increased, while the methane production was decreased compared to the control. In particular, Arisaema ringens extract led to decrease methane production by more than 43%. In addition, the result of real-time polymerase chain reaction indicted that the protozoa population in all added MHEs decreased more than that of the control. In conclusion, the results of this study indicated that MHEs could have properties that decrease ruminal methanogenesis by inhibiting protozoa species and might be promising feed additives for ruminants. PMID:27004810

  2. Effects of Medicinal Herb Extracts on In vitro Ruminal Methanogenesis, Microbe Diversity and Fermentation System.

    PubMed

    Kim, Eun Tae; Hwang, Hee Soon; Lee, Sang Min; Lee, Shin Ja; Lee, Il Dong; Lee, Su Kyoung; Oh, Da Som; Lim, Jung Hwa; Yoon, Ho Baek; Jeong, Ha Yeon; Im, Seok Ki; Lee, Sung Sill

    2016-09-01

    This study was aimed to evaluate the in vitro effects of medicinal herb extracts (MHEs) on ruminal fermentation characteristics and the inhibition of protozoa to reduce methane production in the rumen. A fistulated Hanwoo was used as a donor of rumen fluid. The MHEs (T1, Veratrum patulum; T2, Iris ensata var. spontanea; T3, Arisaema ringens; T4, Carduus crispus; T5, Pueraria thunbergiana) were added to the in vitro fermentation bottles containing the rumen fluid and medium. Total volatile fatty acid (tVFA), total gas production, gas profiles, and the ruminal microbe communities were measured. The tVFA concentration was increased or decreased as compared to the control, and there was a significant (p<0.05) difference after 24 h incubation. pH and ruminal disappearance of dry matter did not show significant difference. As the in vitro ruminal fermentation progressed, total gas production in added MHEs was increased, while the methane production was decreased compared to the control. In particular, Arisaema ringens extract led to decrease methane production by more than 43%. In addition, the result of real-time polymerase chain reaction indicted that the protozoa population in all added MHEs decreased more than that of the control. In conclusion, the results of this study indicated that MHEs could have properties that decrease ruminal methanogenesis by inhibiting protozoa species and might be promising feed additives for ruminants. PMID:27004810

  3. Polyacrylamide added as a nitrogen source stimulates methanogenesis in consortia from various wastewaters.

    PubMed

    Haveroen, Melissa E; MacKinnon, Michael D; Fedorak, Phillip M

    2005-09-01

    Polyacrylamides are widely used as flocculants to enhance clarification of drinking waters and domestic wastewaters, for stabilization of agricultural soils, and to aid in managing mine tailings. The flocs produced with polyacrylamide may be deposited into retention areas that become anaerobic. Although it is unlikely that the carbon backbone of these polymers would be cleaved by microbial activity, the amide group could serve as a nitrogen source for microorganisms. Previous studies have shown that aerobic bacteria utilize the nitrogen from polyacrylamide. This study assessed whether methanogenesis was stimulated when an anionic polyacrylamide (Magnafloc LT27AG) was the sole fixed nitrogen source in serum-bottle microcosms. Microorganisms from two oil sands tailings sources, and a domestic anaerobic sewage sludge were used, with benzoate or acetate provided as carbon and energy sources. In each inoculum-substrate combination, the presence of polyacrylamide-enhanced methane production, indicating that polyacrylamide may stimulate microbial activities in anaerobic environments that are rich in fermentable carbon, but lack nitrogen sources. PMID:16023701

  4. Co-occurrence of methanogenesis and N2 fixation in oil sands tailings.

    PubMed

    Collins, C E Victoria; Foght, Julia M; Siddique, Tariq

    2016-09-15

    Oil sands tailings ponds in northern Alberta, Canada have been producing biogenic gases via microbial metabolism of hydrocarbons for decades. Persistent methanogenic activity in tailings ponds without any known replenishment of nutrients such as fixed nitrogen (N) persuaded us to investigate whether N2 fixation or polyacrylamide (PAM; used as a tailings flocculant) could serve as N sources. Cultures comprising mature fine tailings (MFT) plus methanogenic medium supplemented with or deficient in fixed N were incubated under an N2 headspace. Some cultures were further amended with citrate, which is used in oil sands processing, as a relevant carbon source, and/or with PAM. After an initial delay, N-deficient cultures with or without PAM produced methane (CH4) at the same rate as N-containing cultures, indicating a mechanism of overcoming apparent N-deficiency. Acetylene reduction and (15)N2 incorporation in all N-deficient cultures (with or without PAM) suggested active N2 fixation concurrently with methanogenesis but inability to use PAM as a N source. 16S rRNA gene pyrosequencing revealed little difference between archaeal populations regardless of N content. However, bacterial sequences in N-deficient cultures showed enrichment of Hyphomicrobiaceae and Clostridium members that might contain N2-fixing species. The results are important in understanding long-term production of biogenic greenhouse gases in oil sands tailings. PMID:27177137

  5. Thermophilic microbial cellulose decomposition and methanogenesis pathways recharacterized by metatranscriptomic and metagenomic analysis

    PubMed Central

    Xia, Yu; Wang, Yubo; Fang, Herbert H. P.; Jin, Tao; Zhong, Huanzi; Zhang, Tong

    2014-01-01

    The metatranscriptomic recharacterization in the present study captured microbial enzymes at the unprecedented scale of 40,000 active genes belonged to 2,269 KEGG functions were identified. The novel information obtained herein revealed interesting patterns and provides an initial transcriptional insight into the thermophilic cellulose methanization process. Synergistic beta-sugar consumption by Thermotogales is crucial for cellulose hydrolysis in the thermophilic cellulose-degrading consortium because the primary cellulose degraders Clostridiales showed metabolic incompetence in subsequent beta-sugar pathways. Additionally, comparable transcription of putative Sus-like polysaccharide utilization loci (PULs) was observed in an unclassified order of Bacteroidetes suggesting the importance of PULs mechanism for polysaccharides breakdown in thermophilic systems. Despite the abundance of acetate as a fermentation product, the acetate-utilizing Methanosarcinales were less prevalent by 60% than the hydrogenotrophic Methanobacteriales. Whereas the aceticlastic methanogenesis pathway was markedly more active in terms of transcriptional activities in key genes, indicating that the less dominant Methanosarcinales are more active than their hydrogenotrophic counterparts in methane metabolism. These findings suggest that the minority of aceticlastic methanogens are not necessarily associated with repressed metabolism, in a pattern that was commonly observed in the cellulose-based methanization consortium, and thus challenge the causal likelihood proposed by previous studies. PMID:25330991

  6. Inhibition of Methanogenesis from Acetate in Granular Sludge by Long-Chain Fatty Acids

    PubMed Central

    Koster, Iman W.; Cramer, Albertus

    1987-01-01

    The effect of four saturated long-chain fatty acids (caprylic, capric, lauric, and myristic) and one unsaturated long-chain fatty acid (oleic) on the microbial formation of methane from acetate was investigated in batch anaerobic toxicity assays. The tests were carried out with granular sludge from an upflow anaerobic sludge bed reactor. In this sludge, Methanothrix spp. are the predominant acetoclastic methanogens. Lauric acid appeared to be the most versatile inhibitor: inhibition started at 1.6 mM, and at 4.3 mM the maximum specific acetoclastic methanogenic activity had been reduced to 50%. Caprylic acid appeared to be only slightly inhibitory. Oleic acid was almost as inhibitory as lauric acid. Although adsorption of the inhibitor on the cell wall might play an important role in the mechanism of inhibition, the inhibition was found to be correlated with concentration rather than with the amount per unit of biomass. In practical situations, as in anaerobic waste treatment processes, synergism can be expected to enhance the inhibition of methanogenesis. In the present research a background concentration of lauric acid below its MIC strongly enhanced the toxicity of capric acid and (to an even greater extent) myristic acid. PMID:16347288

  7. Anaerobic sulfamethoxazole degradation is driven by homoacetogenesis coupled with hydrogenotrophic methanogenesis.

    PubMed

    Cetecioglu, Z; Ince, B; Orhon, D; Ince, O

    2016-03-01

    In this study, microbial community dynamics were assessed in two lab-scale anaerobic sequencing batch reactors (ASBRs). One of the reactors was fed by synthetic pharmaceutical industry wastewater with sulfamethoxazole (SMX) as the test reactor and the other without sulfamethoxazole as the control reactor. DNA based DGGE results indicated that Clostiridum sp. became dominant in the SMX reactor while the inoculum was dominated with Firmicutes (61%) and Methanomicrobiales (28%). However their abundances in active community decreased through the last phase. Also the abundance of hydrogenotrophs was high in each phase, while acetoclastic methanogens disappeared in the last phase. Q-PCR analysis revealed that there is a significant reduction in the bacterial community approximately 84%, while methanogens increased to 97% through the operation. Additionally an increase in the expression level of bacterial and methanogenic 16S rRNA (60% and 20%, respectively) was detected. Significant correlation between microbial community and the reactor operation data was found. The study demonstrated that the microbial community maintains the system stability under high antibiotic concentration and long-term operation by homoacetogenesis coupled with hydrogenotrophic methanogenesis. PMID:26724442

  8. Stable carbon isotope discrimination in rice field soil during acetate turnover by syntrophic acetate oxidation or acetoclastic methanogenesis

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf; Klose, Melanie

    2011-03-01

    Rice fields are an important source for the greenhouse gas methane. In Italian rice field soil CH 4 is produced either by hydrogenotrophic and acetoclastic methanogenesis, or by hydrogenotrophic methanogenesis and syntrophic acetate oxidation when temperatures are below and above about 40-45 °C, respectively. In order to see whether these acetate consumption pathways differently discriminate the stable carbon isotopes of acetate, we measured the δ 13C of total acetate and acetate-methyl as well as the δ 13C of CO 2 and CH 4 in rice field soil that had been pre-incubated at 45 °C and then shifted to different temperatures between 25 and 50 °C. Acetate transiently accumulated to about 6 mM, which is about one-third of the amount of CH 4 produced, irrespective of the incubation temperature and the CH 4 production pathway involved. However, the patterns of δ 13C of the CH 4 and CO 2 produced were different at low (25, 30, 35 °C) versus high (40, 45, 50 °C) temperatures. These patterns were consistent with CH 4 being exclusively formed by hydrogenotrophic methanogenesis at high temperatures, and by a combination of acetoclastic and hydrogenotrophic methanogenesis at low temperatures. The patterns of δ 13C of total acetate and acetate-methyl were also different at high versus low temperatures, indicating the involvement of different pathways of production and consumption of acetate at the two temperature regimes. Isotope fractionation during consumption of the methyl group of acetate was more pronounced at low ( α = 1.010-1.025) than at high ( α = 1.0-1.01) temperatures indicating that acetoclastic methanogenesis exhibits a stronger isotope effect than syntrophic acetate oxidation. Small amounts of propionate also transiently accumulated and were analyzed for δ 13C. The δ 13C values slightly increased (by about 10‰) during production and consumption of propionate, but were not affected by incubation temperature. Collectively, our results showed distinct

  9. Dementia and driving

    MedlinePlus

    ... not drive at times of the day when traffic is heaviest. Do not drive when the weather is bad. Do not drive long distances. Drive only on roads the person is used to. Caregivers should try to lessen ...

  10. Experimental pressure enhancement of the rate of homogenous methanogenesis: implications for abiotic methane yields in terrestrial and planetary environments

    NASA Astrophysics Data System (ADS)

    Lazar, C.; Cody, G. D.

    2011-12-01

    Abiotic methane may play a role in the development of a biosphere on an otherwise lifeless planet. Methane concentrations in fluids emanating from serpentinite-hosted submarine springs such as Rainbow and Logatchev are below that required for equilibrium with coexisting CO2 and H2, indicating that the compositions of such fluids may be kinetically-controlled. The presence of transition metal-bearing accessory minerals in serpentinites has led to the hypothesis that heterogeneous catalysis may influence the rate of methanogenesis. We present new experiments that show pressure can also significantly accelerate homogenous methanogenesis, i.e., methane production in the absence of mineral catalysts. A series of cold-seal experiments were performed from 1-3.5 kbar at 300C for two weeks, using dilute isotopically labeled formic acid as a carbon and hydrogen source (70mmol solution). The experiments showed a significant increase in 13CH4 yield with pressure: e.g., the yield at 3.5 kbar was ~20X the yield at 1 kbar. This pressure enhancement is consistent with our previous results on homogeneous and heterogeneous methanogenesis and suggests that mineral catalysts are not necessary for CH4 equilibration in high pressure environments such as Precambrian crystalline basements or regional blueschist-grade metamorphic systems. Furthermore, in hydrothermal systems wherein fluid residence times are too short to permit equilibration, the reaction progress of methanogenesis is expected to increase with pressure. Recently discovered methane plumes above the mid-Cayman trough have been attributed to methanogenesis in deep serpentinites-hosted springs. The current experimental results lead to the prediction that the mid-Cayman springs (>1 kbar) contain higher methane concentrations than their lower pressure analogues at Rainbow and Logatchev (<0.5kbar). Fluids escaping forearc serpentinization in cold, steeply-dipping subduction zones may yield more methane than in warm shallow

  11. Methane production in microbial reverse-electrodialysis methanogenesis cells (MRMCs) using thermolytic solutions.

    PubMed

    Luo, Xi; Zhang, Fang; Liu, Jia; Zhang, Xiaoyuan; Huang, Xia; Logan, Bruce E

    2014-01-01

    The utilization of bioelectrochemical systems for methane production has attracted increasing attention, but producing methane in these systems requires additional voltage to overcome large cathode overpotentials. To eliminate the need for electrical grid energy, we constructed a microbial reverse-electrodialysis methanogenesis cell (MRMC) by placing a reverse electrodialysis (RED) stack between an anode with exoelectrogenic microorganisms and a methanogenic biocathode. In the MRMC, renewable salinity gradient energy was converted to electrical energy, thus providing the added potential needed for methane evolution from the cathode. The feasibility of the MRMC was examined using three different cathode materials (stainless steel mesh coated with platinum, SS/Pt; carbon cloth coated with carbon black, CC/CB; or a plain graphite fiber brush, GFB) and a thermolytic solution (ammonium bicarbonate) in the RED stack. A maximum methane yield of 0.60 ± 0.01 mol-CH4/mol-acetate was obtained using the SS/Pt biocathode, with a Coulombic recovery of 75 ± 2% and energy efficiency of 7.0 ± 0.3%. The CC/CB biocathode MRMC had a lower methane yield of 0.55 ± 0.02 mol-CH4/mol-acetate, which was twice that of the GFB biocathode MRMC. COD removals (89-91%) and Coulombic efficiencies (74-81%) were similar for all cathode materials. Linear sweep voltammetry and electrochemical impedance spectroscopy tests demonstrated that cathodic microorganisms enhanced electron transfer from the cathode compared to abiotic controls. These results show that the MRMC has significant potential for production of nearly pure methane using low-grade waste heat and a source of waste organic matter at the anode. PMID:25010133

  12. Insights into Methane Formation Temperatures, Biogenic Methanogenesis, and Natural Methane Emissions from Clumped Isotopes

    NASA Astrophysics Data System (ADS)

    Douglas, P. M.; Stolper, D. A.; Walter Anthony, K. M.; Dallimore, S.; Paull, C. K.; Wik, M.; Crill, P. M.; Winterdahl, M.; Smith, D. A.; Luhmann, A. J.; Ding, K.; Seyfried, W. E., Jr.; Eiler, J. M.; Ponton, C.; Sessions, A. L.

    2015-12-01

    Multiply substituted isotopologues of methane are a valuable new tool for characterizing and understanding the source of methane in different Earth environments. Here we present methane clumped isotope results from natural gas wells, hydrothermal vents, marine and lacustrine methane seeps, and culture experiments. We observe a wide range of formation temperatures for thermogenic methane. Methane samples from low-maturity reservoirs indicate formation temperatures between 102-144° C, high-maturity conventional and shale gasses indicate temperatures between 158-246 °C, and thermogenic coal gases indicate temperatures between 174-267 °C. Methane formation temperatures generally correlate positively with δ13C, and negatively with gas wetness indices. Methane samples from a set of marine hydrothermal vents indicate a formation temperature of 290-350 °C. Methane sampled from subsurface and marine biogenic sources typically indicate temperatures consistent with the formation environment (0-64° C). In contrast, freshwater biogenic methane samples, and cultures of hydrogenotrophic and methylotrophic methanogens, express low levels of isotopic clumping inconsistent with their formation temperature. These data and complementary models suggest that kinetic isotope effects, likely modulated by rates and pathways of methanogenesis, affect biogenic methane in cultures and freshwater environments. Alternatively, non-equilibrium signatures may result from mixing of methane with widely differing δD and δ13C values. Analyses of biogenic methane emissions from lakes indicate a correlation between methane flux and non-equilibrium clumped isotope fractionations in a given lake. Results from large methane seeps in Alaskan lakes confirm that some seeps emit thermogenic methane, but also indicate that other seeps emit subsurface biogenic methane or variable mixtures of biogenic and thermogenic methane. These results point to diverse sources for large Arctic methane seeps.

  13. Seasonal Changes in Methanogenesis and Methanogenic Community in Three Peatlands, New York State

    PubMed Central

    Sun, Christine L.; Brauer, Suzanna L.; Cadillo-Quiroz, Hinsby; Zinder, Stephen H.; Yavitt, Joseph B.

    2012-01-01

    Fluctuating environmental conditions can promote diversity and control dominance in community composition. In addition to seasonal temperature and moisture changes, seasonal supply of metabolic substrates selects populations temporally. Here we demonstrate cascading effects in the supply of metabolic substrates on methanogenesis and community composition of anaerobic methanogenic archaea in three contrasting peatlands in upstate New York. Fresh samples of peat soils, collected about every 3 months for 20 months and incubated at 22 ± 2°C regardless of the in situ temperature, exhibited potential rates of methane (CH4) production of 0.02–0.2 mmol L−1 day−1 [380–3800 nmol g−1 (dry) day−1). The addition of acetate stimulated rates of CH4 production in a fen peatland soil, whereas addition of hydrogen (H2), and simultaneous inhibition of H2-consuming acetogenic bacteria with rifampicin, stimulated CH4 production in two acidic bog soils, especially, in autumn and winter. The methanogenic community structure was characterized using T-RFLP analyses of SSU rRNA genes. The E2 group of methanogens (Methanoregulaceae) dominated in the two acidic bog peatlands with relatively greater abundance in winter. In the fen peatland, the E1 group (Methanoregulaceae) and members of the Methanosaetaceae were co-dominant, with E1 having a high relative abundance in spring. Change in relative abundance profiles among methanogenic groups in response to added metabolic substrates was as predicted. The acetate-amendment increased abundance of Methanosarcinaceae, and H2-amendment enhanced abundance of E2 group in all peat soils studied, respectively. Additionally, addition of acetate increased abundance of Methanosaetaceae only in the bog soils. Variation in the supply of metabolic substrates helps explain the moderate diversity of methanogens in peatlands. PMID:22408638

  14. Physicochemical impacts associated with natural gas development on methanogenesis in deep sand aquifers.

    PubMed

    Katayama, Taiki; Yoshioka, Hideyoshi; Muramoto, Yoshiyuki; Usami, Jun; Fujiwara, Kazuhiro; Yoshida, Satoshi; Kamagata, Yoichi; Sakata, Susumu

    2015-02-01

    The Minami-Kanto gas field, where gases are dissolved in formation water, is a potential analogue for a marine gas hydrate area because both areas are characterized by the accumulation of microbial methane in marine turbidite sand layers interbedded with mud layers. This study examined the physicochemical impacts associated with natural gas production and well drilling on the methanogenic activity and composition in this gas field. Twenty-four gas-associated formation water samples were collected from confined sand aquifers through production wells. The stable isotopic compositions of methane in the gases indicated their origin to be biogenic via the carbonate reduction pathway. Consistent with this classification, methanogenic activity measurements using radiotracers, culturing experiments and molecular analysis of formation water samples indicated the predominance of hydrogenotrophic methanogenesis. The cultivation of water samples amended only with methanogenic substrates resulted in significant increases in microbial cells along with high-yield methane production, indicating the restricted availability of substrates in the aquifers. Hydrogenotrophic methanogenic activity increased with increasing natural gas production from the corresponding wells, suggesting that the flux of substrates from organic-rich mudstones to adjacent sand aquifers is enhanced by the decrease in fluid pressure in sand layers associated with natural gas/water production. The transient predominance of methylotrophic methanogens, observed for a few years after well drilling, also suggested the stimulation of the methanogens by the exposure of unutilized organic matter through well drilling. These results provide an insight into the physicochemical impacts on the methanogenic activity in biogenic gas deposits including marine gas hydrates. PMID:25105906

  15. Mapping the Environmental Boundaries for Methanogenesis in Serpentinizing Systems using a Cell-scale Numerical Model

    NASA Astrophysics Data System (ADS)

    Alperin, M. J.; Hoehler, T. M.; McCollom, T.

    2011-12-01

    Serpentinizing systems occur where liquid water reacts with ultramafic minerals. The reaction releases heat and produces an alkaline fluid that is rich in H2. The abundant H2 suggests that the energetics of methane production by CO2 reduction is highly favorable (ΔG ~ -102 kJ/mol CH4 for [H2] ~ 10-2 M). Given the possibility of subsurface water and ultramafic minerals on Mars, methanogenesis in serpentinizing systems has been considered as a possible model for photosynthesis-independent, extraterrestrial life. However, the high pH (9 - 11) and possibly elevated temperature have a negative impact on the overall cellular energy balance by increasing the cell's maintenance energy and reducing the concentration of CO2 substrate. We developed a reaction-transport model on the scale of a methanogen cell to investigate how the overall bioenergetics of methane production is influenced by the interplay between pH, temperature, and H2 and CO2 concentration. The model differentiates the cell into three basic structural units (cell wall, cell membrane with gated ion channels, and cytoplasm) and employs both thermodynamic and kinetic controls to estimate an upper-limit energy yield as a function of environmental conditions. The model provides a map of the range of environmental extremes for which the energy balance for microbial methane production is positive. The model also provides a tool for exploring the energetics of different metabolic strategies that methanogens could use to cope with stresses associated with life in an alkaline, low-CO2 environment.

  16. Physicochemical impacts associated with natural gas development on methanogenesis in deep sand aquifers

    PubMed Central

    Katayama, Taiki; Yoshioka, Hideyoshi; Muramoto, Yoshiyuki; Usami, Jun; Fujiwara, Kazuhiro; Yoshida, Satoshi; Kamagata, Yoichi; Sakata, Susumu

    2015-01-01

    The Minami-Kanto gas field, where gases are dissolved in formation water, is a potential analogue for a marine gas hydrate area because both areas are characterized by the accumulation of microbial methane in marine turbidite sand layers interbedded with mud layers. This study examined the physicochemical impacts associated with natural gas production and well drilling on the methanogenic activity and composition in this gas field. Twenty-four gas-associated formation water samples were collected from confined sand aquifers through production wells. The stable isotopic compositions of methane in the gases indicated their origin to be biogenic via the carbonate reduction pathway. Consistent with this classification, methanogenic activity measurements using radiotracers, culturing experiments and molecular analysis of formation water samples indicated the predominance of hydrogenotrophic methanogenesis. The cultivation of water samples amended only with methanogenic substrates resulted in significant increases in microbial cells along with high-yield methane production, indicating the restricted availability of substrates in the aquifers. Hydrogenotrophic methanogenic activity increased with increasing natural gas production from the corresponding wells, suggesting that the flux of substrates from organic-rich mudstones to adjacent sand aquifers is enhanced by the decrease in fluid pressure in sand layers associated with natural gas/water production. The transient predominance of methylotrophic methanogens, observed for a few years after well drilling, also suggested the stimulation of the methanogens by the exposure of unutilized organic matter through well drilling. These results provide an insight into the physicochemical impacts on the methanogenic activity in biogenic gas deposits including marine gas hydrates. PMID:25105906

  17. Activation of Methanogenesis in Arid Biological Soil Crusts Despite the Presence of Oxygen

    PubMed Central

    Angel, Roey; Matthies, Diethart; Conrad, Ralf

    2011-01-01

    Methanogenesis is traditionally thought to occur only in highly reduced, anoxic environments. Wetland and rice field soils are well known sources for atmospheric methane, while aerated soils are considered sinks. Although methanogens have been detected in low numbers in some aerated, and even in desert soils, it remains unclear whether they are active under natural oxic conditions, such as in biological soil crusts (BSCs) of arid regions. To answer this question we carried out a factorial experiment using microcosms under simulated natural conditions. The BSC on top of an arid soil was incubated under moist conditions in all possible combinations of flooding and drainage, light and dark, air and nitrogen headspace. In the light, oxygen was produced by photosynthesis. Methane production was detected in all microcosms, but rates were much lower when oxygen was present. In addition, the δ13C of the methane differed between the oxic/oxygenic and anoxic microcosms. While under anoxic conditions methane was mainly produced from acetate, it was almost entirely produced from H2/CO2 under oxic/oxygenic conditions. Only two genera of methanogens were identified in the BSC-Methanosarcina and Methanocella; their abundance and activity in transcribing the mcrA gene (coding for methyl-CoM reductase) was higher under anoxic than oxic/oxygenic conditions, respectively. Both methanogens also actively transcribed the oxygen detoxifying gene catalase. Since methanotrophs were not detectable in the BSC, all the methane produced was released into the atmosphere. Our findings point to a formerly unknown participation of desert soils in the global methane cycle. PMID:21655270

  18. Thermodynamic Constraints on Sulfate Reduction and Methanogenesis in a Coalbed Methane Reservoir

    NASA Astrophysics Data System (ADS)

    Kirk, M. F.; Marquart, K. A.; Wilson, B. H.; Flynn, T. M.; Vinson, D. S.

    2014-12-01

    In this study we consider how commercial natural gas production could affect sulfate reduction and methanogenesis in coal-bearing sediments of the Cherokee Basin, Kansas, USA. Controls on the activity of these two groups of microbes are important to understand because their activity and interactions may influence methane formation and retention in unconventional reservoirs. During November 2013, we collected water and gas samples from 16 commercial gas wells for geochemical and microbiological analysis. Results indicate that methane in the coalbeds formed biologically and that both methanogens and sulfate reducers are present. Gas samples consisted almost entirely of methane (C1/(C2+C3) = 2638 on avg.) and the δD and δ13C of methane averaged -222‰ VSMOW and -61‰ VPDB, respectively. Archaeal sequences in our samples were nearly all classified within groups of methanogens (avg. 91%) and cultivable methanogens were present in all water samples. On average, 6% of the bacterial sequences from our samples were classified in groups of sulfate reducers and sulfate available to support their activity ranged up to 110 μM in concentration. Any interaction that occurs between these groups may be influenced by the energetics of their metabolic reactions. Thermodynamic calculations show that methanogens hold an energy advantage over sulfate reducers if dissolved methane concentrations are low. Under current conditions, methanogens see between 12 and 16 kJ mol-1 more usable free energy than sulfate reducers, if we assume a minimal methane concentration (1 μM). However, usable energy for methanogens would equal that available to sulfate reducers at methane concentrations ranging between 144 and 831 μM, well below saturation levels. Production activities that hold methane concentration below these levels, therefore, would help maintain an energy advantage for methanogens. In contrast, if production activities cause sulfate concentrations to increase, sulfate reducers would

  19. Methylthiol:coenzyme M methyltransferase from Methanosarcina barkeri, an enzyme of methanogenesis from dimethylsulfide and methylmercaptopropionate.

    PubMed Central

    Tallant, T C; Krzycki, J A

    1997-01-01

    During growth on acetate, Methanosarcina barkeri expresses catabolic enzymes for other methanogenic substrates such as monomethylamine. The range of substrates used by cells grown on acetate was further explored, and it was found that cells grown on acetate also converted dimethylsulfide (DMS) and methylmercaptopropionate (MMPA) to methane. Cells or extracts of cells grown on trimethylamine or methanol did not utilize either DMS or MMPA. During growth on acetate, cultures demethylated MMPA, producing methane and mercaptopropionate. Extracts of acetate-grown cells possessed DMS- and MMPA-dependent coenzyme M (CoM) methylation activities. The activity peaks of CoM methylation with either DMS or MMPA coeluted upon gel permeation chromatography of extracts of acetate-grown cells consistent with an apparent molecular mass of 470 kDa. A 480-kDa corrinoid protein, previously demonstrated to be a CoM methylase but otherwise of unknown physiological function, was found to methylate CoM with either DMS or MMPA. MMPA was demethylated by the purified 480-kDa CoM methylase, consuming 1 mol of CoM and producing 1 mol of mercaptopropionate. DMS was demethylated by the purified protein, consuming 1 mol of CoM and producing 1 mol of methanethiol. The methylthiol:CoM methyltransferase reaction could be initiated only with the enzyme-bound corrinoid in the methylated state. CoM could demethylate, and DMS and MMPA could remethylate, the corrinoid cofactor. The monomethylamine corrinoid protein and the A isozyme of methylcobamide:CoM methyltransferase (proteins homologous to the two subunits comprising the 480-kDa CoM methylase) did not catalyze CoM methylation with methylated thiols. These results indicate that the 480-kDa corrinoid protein functions as a CoM methylase during methanogenesis from DMS or MMPA. PMID:9371433

  20. Methanogenesis in a Thermophilic (58°C) Anaerobic Digestor: Methanothrix sp. as an Important Aceticlastic Methanogen

    PubMed Central

    Zinder, S. H.; Cardwell, S.C.; Anguish, T.; Lee, M.; Koch, M.

    1984-01-01

    Aceticlastic methanogens and other microbial groups were enumerated in a 58°C laboratory-scale (3 liter) anaerobic digestor which was fed air-classified municipal refuse, a lignocellulosic waste (loading rate = 1.8 to 2.7 g of volatile solids per liter per day; retention time = 10 days). Two weeks after start-up, Methanosarcina sp. was present in high numbers (105 to 106 CFU/ml) and autofluorescent Methanosarcina-like clumps were abundant in sludge examined by using epifluorescence microscopy. After about 4 months of digestor operation, numbers of Methanosarcina sp. dropped 2 to 3 orders of magnitude and large numbers (most probable number = 106 to 107/ml) of a thermophilic aceticlastic methanogen morphologically resembing Methanothrix sp. were found. Methanothrix sp. had apparently displaced Methanosarcina sp. as the dominant aceticlastic methanogen in the digestor. During the period when Methanothrix sp. was apparently dominant, acetate concentrations varied between 0.3 and 1.5 μmol/ml during the daily feeding cycle, and acetate was the precursor of 63 to 66% of the methane produced during peak digestor methanogenesis. The apparent Km value obtained for methanogenesis from acetate, 0.3 μmol/ml, indicated that the aceticlastic methanogens were nearly saturated for substrate during most of the digestor cycle. CO2-reducing methanogens were capable of methanogenesis at rates more than 12 times greater than those usually found in the digestor. Added propionate (4.5 μmol/ml) was metabolized slowly by the digestor populations and slightly inhibited methanogenesis. Added n-butyrate, isobutyrate, or n-valerate (4.5 μmol/ml each) were broken down within 24 h. Isobutyrate was oxidized to acetate, a novel reaction possibly involving isomerization to n-butyrate. The rapid growth rate and versatile metabolism of Methanosarcina sp. make it a likely organism to be involved in start-up, whereas the low Km value of Methanothrix sp. for acetate may cause it to be favored in

  1. [Influence of nitrate on the simultaneous methanogenesis and denitrification reaction of anaerobic biofilm and granular sludge].

    PubMed

    Zhong, Chen-Yu; Ye, Jie-Xu; Li, Ruo-Yu; Chen, Sheng; Sun, De-Zhi

    2012-12-01

    The aims of this study are to further investigate the impact mechanism of nitrate on the simultaneous methanogenesis and denitrification (SMD) process of anaerobic biofilm, and to extend the application of the biofilm process in the treatment of high nitrogen and COD concentration organic wastewater. The SMD reactions were successfully carried out in a hybrid anaerobic biofilm and sludge reactor (HABSR) and an up-flow anaerobic sludge blanket (UASB), and the influence of nitrate on the performance of simultaneous carbon and nitrogen removal in biofilm and granular sludge were investigated using batch tests. The results showed that the nitrate concentration could obviously affect the carbon and nitrogen removal in both biofilm and granular sludge, and the increase of nitrate concentration had more serious impact on the granular sludge, and the biofilm presented higher COD and nitrogen removal efficiency and stronger resistance to toxic materials than the granular sludge. As the nitrate concentration was increased from 75 to 600 mg x L(-1), the COD removal rates were reduced from 273.26 to 0.1 mg x (h x g)(-1) in granular sludge and reduced from 95 to 1.7 mg x (h x g)(-1) in biofilm. At the same time, the denitrification rate of biofilm and granular sludge were increased form 21.43 and 22.31 mg x (h x g)(-1) to 83.72 and 61.06 mg x (h x g)(-1), respectively. The biofilm recovered the COD degradation rate more quickly and easily than the granular sludge, and the maximum COD removal rate reached 712.44 mg x (h x g)(-1). The nitrite accumulation was observed to be the major cause that affected the simultaneous carbon and nitrogen removal of biofilm and granular sludge. It's found that the maximum nitrite accumulation in biofilm was only one tenth of that of the granular sludge at the same nitrate concentration. The HABSR was proved to be an important alternative for SMD reaction employed in the treatment of high nitrogen and COD concentration organic wastewater. PMID

  2. Biogas Upgrading via Hydrogenotrophic Methanogenesis in Two-Stage Continuous Stirred Tank Reactors at Mesophilic and Thermophilic Conditions.

    PubMed

    Bassani, Ilaria; Kougias, Panagiotis G; Treu, Laura; Angelidaki, Irini

    2015-10-20

    This study proposes an innovative setup composed by two stage reactors to achieve biogas upgrading coupling the CO2 in the biogas with external H2 and subsequent conversion into CH4 by hydrogenotrophic methanogenesis. In this configuration, the biogas produced in the first reactor was transferred to the second one, where H2 was injected. This configuration was tested at both mesophilic and thermophilic conditions. After H2 addition, the produced biogas was upgraded to average CH4 content of 89% in the mesophilic reactor and 85% in the thermophilic. At thermophilic conditions, a higher efficiency of CH4 production and CO2 conversion was recorded. The consequent increase of pH did not inhibit the process indicating adaptation of microorganisms to higher pH levels. The effects of H2 on the microbial community were studied using high-throughput Illumina random sequences and full-length 16S rRNA genes extracted from the total sequences. The relative abundance of archaeal community markedly increased upon H2 addition with Methanoculleus as dominant genus. The increase of hydrogenotrophic methanogens and syntrophic Desulfovibrio and the decrease of aceticlastic methanogens indicate a H2-mediated shift toward the hydrogenotrophic pathway enhancing biogas upgrading. Moreover, Thermoanaerobacteraceae were likely involved in syntrophic acetate oxidation with hydrogenotrophic methanogens in absence of aceticlastic methanogenesis. PMID:26390125

  3. Efficacy of different methanolic plant extracts on anti-methanogenesis, rumen fermentation and gas production kinetics in vitro

    PubMed Central

    Sirohi, S.K.; Goel, N.; Pandey, P.

    2012-01-01

    The present study was carried out to evaluate the effect of methanolic extracts of three plants, mehandi (Lawsonia inermis), jaiphal (Myristica fragrans) and green chili (Capsicum annuum) on methanogenesis, rumen fermentation and fermentation kinetic parameters by in vitro gas production techniques. Single dose of each plant extract (1 ml / 30 ml buffered rumen fluid) and two sorghum fodder containing diets (high and low fiber diets) were used for evaluating the effect on methanogenesis and rumen fermentation pattern, while sequential incubations (0, 1, 2, 3, 6 9, 12, 24, 36, 48, 60, 72 and 96 h) were carried out for gas production kinetics. Results showed that methane production was reduced, ammonia nitrogen was increased significantly, while no significant effect was found on pH and protozoal population following addition of different plant extracts in both diets except mehandi. Green chili significantly reduced digestibility of dry matter, total fatty acid and acetate concentration at incubation with sorghum based high and low fiber diets. Among all treatments, green chili increased potential gas production, while jaiphal decreased the gas production rate constant significantly. The present results demonstrate that methanolic extracts of different plants are promising rumen modifying agents. They have the potential to modulate the methane production, potential gas production, gas production rate constant, dry matter digestibility and microbial biomass synthesis. PMID:26623296

  4. Effect of supplementation of rice bran and fumarate alone or in combination on in vitro rumen fermentation, methanogenesis and methanogens.

    PubMed

    Abrar, Arfan; Kondo, Makoto; Kitamura, Tasuku; Ban-Tokuda, Tomomi; Matsui, Hiroki

    2016-03-01

    This study investigated the effect of fumarate (FUM) and rice bran (RB), alone and together, on in vitro rumen fermentation, methanogenesis and methanogens. In vitro incubation was performed with six media that were either unsupplemented (control) or supplemented with 10% RB, 5 mmol/L FUM, 10% RB + 5 mmol/L FUM, 10 mmol/L FUM, or 10% RB + 10 mmol/L FUM. Methane (CH4 ) production, dry matter digestibility, CH4 per digested dry matter, total short-chain fatty acid (SCFA) production, proportion of SCFA, acetate : proprionate ratio, production of NH3 -N, and population density of rumen microbes were determined. Supplementation with 10% RB + 10 mmol/L FUM yielded a 36% decrease in CH4 production compared to the control. Supplementation of FUM, in the presence or absence of RB, provided increases in total SCFA production and propionate proportion up to 61% and 31%, respectively. Total bacteria, methanogens and protozoa populations were significantly (P < 0.05) decreased with the 10% RB + 10 mmol/L FUM supplementation. The effect of anti-methanogenesis of FUM was enhanced by the addition of RB. Notably, the CH4 production attenuation was achieved by 10% RB + 10 mmol/L FUM without reduction of digestibility or of ruminal fermentation. PMID:26388080

  5. Effects of polychlorinated biphenyl congener concentration and sediment supplementation on rates of methanogenesis and 2,3,6-trichlorobiphenyl dechlorination in an anaerobic enrichment

    SciTech Connect

    Boyle, A.W.; May, H.D. ); Blake, C.K. ); Price, W.A. )

    1993-09-01

    The release of polychlorinated biphenyls (PCBs) into the environment has caused public concern. PCBs are know known to be susceptible to biodegradation; PCBs in the Hudson river have been shown to be extensively dechlorinated, but the rate of dechlorination in anaerobic environments have been slow, over months or years. This study tested the effects of PCB concentration and sediment supplementation with 2,3,6-trichlorobiphenol, on the rate of PCB dechlorination and methanogenesis. The rates of meta dechlorination in sediment supplemented cultures were measured in the laboratory, including both the rate per bacterial cell and the rate of methanogenesis when dechlorination increases. 24 refs., 3 figs., 1 tab.

  6. Can variable frequency drives reduce irrigation costs for rice producers?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variable Frequency Drives (VFD's) allow for variable speed operation of electrical motor drive irrigation pumps and are an emerging technology for agricultural irrigation, primarily for pressurized irrigation systems. They are considered an energy savings device, but less is known about their app...

  7. Extended Driving Impairs Nocturnal Driving Performances

    PubMed Central

    Sagaspe, Patricia; Taillard, Jacques; Åkerstedt, Torbjorn; Bayon, Virginie; Espié, Stéphane; Chaumet, Guillaume; Bioulac, Bernard; Philip, Pierre

    2008-01-01

    Though fatigue and sleepiness at the wheel are well-known risk factors for traffic accidents, many drivers combine extended driving and sleep deprivation. Fatigue-related accidents occur mainly at night but there is no experimental data available to determine if the duration of prior driving affects driving performance at night. Participants drove in 3 nocturnal driving sessions (3–5am, 1–5am and 9pm–5am) on open highway. Fourteen young healthy men (mean age [±SD] = 23.4 [±1.7] years) participated Inappropriate line crossings (ILC) in the last hour of driving of each session, sleep variables, self-perceived fatigue and sleepiness were measured. Compared to the short (3–5am) driving session, the incidence rate ratio of inappropriate line crossings increased by 2.6 (95% CI, 1.1 to 6.0; P<.05) for the intermediate (1–5am) driving session and by 4.0 (CI, 1.7 to 9.4; P<.001) for the long (9pm–5am) driving session. Compared to the reference session (9–10pm), the incidence rate ratio of inappropriate line crossings were 6.0 (95% CI, 2.3 to 15.5; P<.001), 15.4 (CI, 4.6 to 51.5; P<.001) and 24.3 (CI, 7.4 to 79.5; P<.001), respectively, for the three different durations of driving. Self-rated fatigue and sleepiness scores were both positively correlated to driving impairment in the intermediate and long duration sessions (P<.05) and increased significantly during the nocturnal driving sessions compared to the reference session (P<.01). At night, extended driving impairs driving performances and therefore should be limited. PMID:18941525

  8. Electrical drive for automobile

    SciTech Connect

    Fobbs, H.

    1980-09-16

    Electrical apparatus for driving an automobile is described that is comprised of a dc motor operationally connected to the rear axle through a drive shaft with the motor energized from storage batteries and recharged from alternators coupled to the drive shaft adjacent a clutch at the rear end of the automobile through an auxiliary drive shaft.

  9. Coaxial Redundant Drives

    NASA Technical Reports Server (NTRS)

    Brissette, R.

    1983-01-01

    Harmonic drives allow redundancy and high out put torque in small package. If main drive fails, standby drive takes over and produces torque along same axis as main drive. Uses include power units in robot for internal pipeline inspection, manipulators in deep submersible probes or other applications in which redundancy protects against costly failures.

  10. Solar array drive system

    NASA Technical Reports Server (NTRS)

    Berkopec, F. D.; Sturman, J. C.; Stanhouse, R. W.

    1976-01-01

    A solar array drive system consisting of a solar array drive mechanism and the corresponding solar array drive electronics is being developed. The principal feature of the solar array drive mechanism is its bidirectional capability which enables its use in mechanical redundancy. The solar array drive system is of a widely applicable design. This configuration will be tested to determine its acceptability for generic mission sets. Foremost of the testing to be performed is the testing for extended duration.

  11. Silicate Weathering and Pervasive Authigenic Carbonate Precipitation Coupled to Methanogenesis in the Krishna-Godavari Basin, Offshore India

    NASA Astrophysics Data System (ADS)

    Solomon, E. A.; Spivack, A. J.; Kastner, M.; Torres, M. E.

    2014-12-01

    The cycling of methane in marine sediments has been actively studied for the past several decades, but less attention has been paid to the cycling of CO2 produced in methanogenic sediments. The National Gas Hydrate Program Expedition 01 cored 10 sites with the Joides Resolution drillship in the Krishna-Godavari basin, located on the southeastern margin of India. A comprehensive suite of pore water solute concentrations and isotope ratios were analyzed to investigate the distribution and concentration of gas hydrate along the margin, in situ diagenetic and metabolic reactions, fluid migration and flow pathways, and fluid and gas sources. This represents one of the most comprehensive pore water geochemical datasets collected at a continental margin to date, and provides the necessary tracers to better understand the processes and sinks controlling CO2 in margin sediments. Our results show that the CO2 produced through net microbial methanogenesis is effectively neutralized through silicate weathering throughout the sediment column drilled at each site (~100-300 m), buffering the pH of the sedimentary pore water and generating excess alkalinity through the same reaction sequence as continental silicate weathering. Most of the excess alkalinity produced through silicate weathering in the Krishna-Godavari basin is sequestered in Ca- and Fe-carbonates as a result of ubiquitous calcium release from weathering detrital silicates and Fe-reduction within the methanogenic sediments. Formation of secondary hydrous silicates (e.g. smectite) related to incongruent primary silicate dissolution acts as a significant sink for pore water Mg, K, Li, Rb, and B. The consumption of methane through anaerobic oxidation of methane, sequestration of methane in gas hydrate, and sequestration of dissolved inorganic carbon in authigenic carbonates keeps methanogenesis as a thermodynamically feasible catabolic pathway. Our results combined with previous indications of silicate weathering in

  12. Identity-Related Influences on the Success of Minority Workers in Primarily Nonminority Organizations.

    ERIC Educational Resources Information Center

    James, Keith; Khoo, Gillian

    1991-01-01

    Reviews literature at the micro- (individual, interpersonal, and small group) and macro- (organizational, societal, and cultural) levels relating to the experiences and outcomes of minorities in work settings populated primarily by members of the majority. Uses Tajfel and Turner's Social Identity Theory as an organizational and integrative…

  13. Autism and Developmental Screening in a Public, Primary Care Setting Primarily Serving Hispanics: Challenges and Results

    ERIC Educational Resources Information Center

    Windham, Gayle C.; Smith, Karen S.; Rosen, Nila; Anderson, Meredith C.; Grether, Judith K.; Coolman, Richard B.; Harris, Stephen

    2014-01-01

    We implemented screening of children 16-30 months of age (n = 1,760) from a typically under-served, primarily Hispanic, population, at routine pediatric appointments using the modified checklist for autism in toddlers (M-CHAT) and Ages and Stages Questionnaire. Screen positive rates of 26 and 39%, respectively, were higher than previous reports.…

  14. 12 CFR 225.127 - Investment in corporations or projects designed primarily to promote community welfare.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Regulation Y (12 CFR 225.25(b)(6)) includes approval to engage, either directly or through a subsidiary, in... Nation's social problems. Although the interpretation primarily focuses on low- and moderate-income... remedying our social ills. Section 225.25(b)(6) is intended to provide an opportunity for them to...

  15. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 3 2011-07-01 2011-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780... AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT Employment in Agriculture and Livestock Auction Operations Under the Section 13(b)(13) Exemption...

  16. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780... AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT Employment in Agriculture and Livestock Auction Operations Under the Section 13(b)(13) Exemption...

  17. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 3 2013-07-01 2013-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780... AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT Employment in Agriculture and Livestock Auction Operations Under the Section 13(b)(13) Exemption...

  18. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 3 2014-07-01 2014-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780... AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT Employment in Agriculture and Livestock Auction Operations Under the Section 13(b)(13) Exemption...

  19. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 3 2012-07-01 2012-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780... AGRICULTURE, PROCESSING OF AGRICULTURAL COMMODITIES, AND RELATED SUBJECTS UNDER THE FAIR LABOR STANDARDS ACT Employment in Agriculture and Livestock Auction Operations Under the Section 13(b)(13) Exemption...

  20. 12 CFR 208.7 - Prohibition against use of interstate branches primarily for deposit production.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 12 Banks and Banking 2 2011-01-01 2011-01-01 false Prohibition against use of interstate branches primarily for deposit production. 208.7 Section 208.7 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM MEMBERSHIP OF STATE BANKING INSTITUTIONS IN THE FEDERAL RESERVE SYSTEM (REGULATION H) General...

  1. 12 CFR 208.7 - Prohibition against use of interstate branches primarily for deposit production.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 12 Banks and Banking 2 2010-01-01 2010-01-01 false Prohibition against use of interstate branches primarily for deposit production. 208.7 Section 208.7 Banks and Banking FEDERAL RESERVE SYSTEM BOARD OF GOVERNORS OF THE FEDERAL RESERVE SYSTEM MEMBERSHIP OF STATE BANKING INSTITUTIONS IN THE FEDERAL RESERVE SYSTEM (REGULATION H) General...

  2. Increased fermentation activity and persistent methanogenesis in a model aquifer system following source removal of an ethanol blend release.

    PubMed

    Ma, Jie; Rixey, William G; Alvarez, Pedro J J

    2015-01-01

    The increased probability of groundwater contamination by ethanol-blended fuel calls for improved understanding of how remediation efforts affect the fate and transport of constituents of concern, including the generation and fate of fermentation byproducts. A pilot-scale (8 m³) model aquifer was used to investigate changes in the concentrations of ethanol and its metabolites (methane and volatile fatty acids) after removal of the contamination source. Following the shut-off of a continuous release of a dissolved ethanol blend (10% v:v ethanol, 50 mg/L benzene, and 50 mg/L toluene), fermentation activity was surprisingly stimulated and the concentrations of ethanol metabolites increased. A microcosm experiment showed that this result was due to a decrease in the dissolved ethanol concentration below its toxicity threshold (∼2000 mg/L for this system). Methane generation (>1.5 mg/L of dissolved methane) persisted for more than 100 days after the disappearance of ethanol, despite clean air-saturated water flowing continuously through the tank at a relative high seepage velocity (0.76 m/day). Quantitative real-time PCR showed that functional genes associated with methane metabolism (mcrA for methanogenesis and pmoA for methanotrophy) also persisted in the aquifer material. Persistent methanogenesis was apparently due to the anaerobic degradation of soil-bound organic carbon (e.g., biomass grown on ethanol and other substrates). Overall, this study reflects the complex plume dynamics following source removal, and suggests that monitoring for increases in the concentration of ethanol metabolites that impact groundwater quality should be considered. PMID:25462754

  3. Changing Feeding Regimes To Demonstrate Flexible Biogas Production: Effects on Process Performance, Microbial Community Structure, and Methanogenesis Pathways

    PubMed Central

    Mulat, Daniel Girma; Jacobi, H. Fabian; Feilberg, Anders; Adamsen, Anders Peter S.; Richnow, Hans-Hermann

    2015-01-01

    Flexible biogas production that adapts biogas output to energy demand can be regulated by changing feeding regimes. In this study, the effect of changes in feeding intervals on process performance, microbial community structure, and the methanogenesis pathway was investigated. Three different feeding regimes (once daily, every second day, and every 2 h) at the same organic loading rate were studied in continuously stirred tank reactors treating distiller's dried grains with solubles. A larger amount of biogas was produced after feeding in the reactors fed less frequently (once per day and every second day), whereas the amount remained constant in the reactor fed more frequently (every 2 h), indicating the suitability of the former for the flexible production of biogas. Compared to the conventional more frequent feeding regimes, a methane yield that was up to 14% higher and an improved stability of the process against organic overloading were achieved by employing less frequent feeding regimes. The community structures of bacteria and methanogenic archaea were monitored by terminal restriction fragment length polymorphism (T-RFLP) analysis of 16S rRNA and mcrA genes, respectively. The results showed that the composition of the bacterial community varied under the different feeding regimes, and the observed T-RFLP patterns were best explained by the differences in the total ammonia nitrogen concentrations, H2 levels, and pH values. However, the methanogenic community remained stable under all feeding regimes, with the dominance of the Methanosarcina genus followed by that of the Methanobacterium genus. Stable isotope analysis showed that the average amount of methane produced during each feeding event by acetoclastic and hydrogenotrophic methanogenesis was not influenced by the three different feeding regimes. PMID:26497462

  4. Methanogens and Methanogenesis in the Rumens and Ceca of Lambs Fed Two Different High-Grain-Content Diets

    PubMed Central

    Morgavi, D. P.; Martin, C.

    2013-01-01

    The amount and nature of dietary starch are known to influence the extent and site of feed digestion in ruminants. However, how starch degradability may affect methanogenesis and methanogens along the ruminant's digestive tract is poorly understood. This study examined the diversity and metabolic activity of methanogens in the rumen and cecum of lambs receiving wheat or corn high-grain-content diets. Methane production in vivo and ex situ was also monitored. In vivo daily methane emissions (CH4 g/day) were 36% (P < 0.05) lower in corn-fed lambs than in wheat-fed lambs. Ex situ methane production (μmol/h) was 4-fold higher for ruminal contents than for cecal contents (P < 0.01), while methanogens were 10-fold higher in the rumen than in the cecum (mcrA copy numbers; P < 0.01). Clone library analysis indicated that Methanobrevibacter was the dominant genus in both sites. Diet induced changes at the species level, as the Methanobrevibacter millerae-M. gottschalkii-M. smithii clade represented 78% of the sequences from the rumen of wheat-fed lambs and just about 52% of the sequences from the rumen of the corn-fed lambs. Diet did not affect mcrA expression in the rumen. In the cecum, however, expression was 4-fold and 2-fold lower than in the rumen for wheat- and corn-fed lambs, respectively. Though we had no direct evidence for compensation of reduced rumen methane production with higher cecum methanogenesis, the ecology of methanogens in the cecum should be better considered. PMID:23241983

  5. Belowground in situ redox dynamics and methanogenesis recovery in a degraded fen during dry-wet cycles and flooding

    NASA Astrophysics Data System (ADS)

    Estop-Aragonés, C.; Knorr, K.-H.; Blodau, C.

    2013-01-01

    Climate change induced drying and flooding may alter the redox conditions of organic matter decomposition in peat soils. The seasonal and intermittent changes in pore water solutes (NO3-, Fe2+, SO42-, H2S, acetate) and dissolved soil gases (CO2, O2, CH4, H2) under natural water table fluctuations were compared to the response under a reinforced drying and flooding in fen peats. Oxygen penetration during dryings led to CO2 and CH4 degassing and to a regeneration of dissolved electron acceptors (NO3-, Fe3+ and SO42-). Drying intensity controlled the extent of the electron acceptor regeneration. Iron was rapidly reduced and sulfate pools ~ 1 mM depleted upon rewetting and CH4 did not substantially accumulate until sulfate levels declined to ~ 100 μmol L-1. The post-rewetting recovery of soil methane concentrations to levels ~ 80 μmol L-1 needed 40-50 days after natural drought. This recovery was prolonged after experimentally reinforced drought. A greater regeneration of electron acceptors during drying was not related to prolonged methanogenesis suppression after rewetting. Peat compaction, solid phase content of reactive iron and total reduced inorganic sulfur and organic matter content controlled oxygen penetration, the regeneration of electron acceptors and the recovery of CH4 production, respectively. Methane production was maintained despite moderate water table decline of 20 cm in denser peats. Flooding led to accumulation of acetate and H2, promoted CH4 production and strengthened the co-occurrence of iron and sulfate reduction and methanogenesis. Mass balances during drying and flooding indicated that an important fraction of the electron flow must have been used for the generation and consumption of electron acceptors in the solid phase or other mechanisms. In contrast to flooding, dry-wet cycles negatively affect methane production on a seasonal scale, but this impact might strongly depend on drying intensity and on the peat matrix, of which structure and

  6. Driving and neurodegenerative diseases.

    PubMed

    Uc, Ergun Y; Rizzo, Matthew

    2008-09-01

    The proportion of elderly people in the general population is rising, resulting in greater numbers of drivers with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. These neurodegenerative disorders impair cognition, visual perception, and motor function, leading to reduced driver fitness and greater crash risk. Yet neither medical diagnosis nor age alone is reliable enough to predict driver safety or crashes or to revoke the driving privileges of these individuals. Driving research utilizes tools such as questionnaires about driving habits and history, driving simulators, standardized road tests utilizing instrumented vehicles, and state driving records. Research challenges include outlining the evolution of driving safety, understanding the mechanisms of driving impairment, and developing a reliable and efficient standardized test battery for prediction of driver safety in neurodegenerative disorders. This information will enable healthcare providers to advise their patients with neurodegenerative disorders with more certainty, affect policy, and help develop rehabilitative measures for driving. PMID:18713573

  7. Gear bearing drive

    NASA Technical Reports Server (NTRS)

    Weinberg, Brian (Inventor); Mavroidis, Constantinos (Inventor); Vranish, John M. (Inventor)

    2011-01-01

    A gear bearing drive provides a compact mechanism that operates as an actuator providing torque and as a joint providing support. The drive includes a gear arrangement integrating an external rotor DC motor within a sun gear. Locking surfaces maintain the components of the drive in alignment and provide support for axial loads and moments. The gear bearing drive has a variety of applications, including as a joint in robotic arms and prosthetic limbs.

  8. Magnetic drive coupling

    NASA Technical Reports Server (NTRS)

    Carter, Edward L. (Inventor)

    1987-01-01

    The driving and driven members of a magnetic drive are separated by en enlarged gap to provide clearance for a conduit or other member. Flux pins in the gap maintain the torque transmitting capability of the drive. The spacing between two of the flux pins is increased to provide space for the conduit.

  9. Magnetic drive coupling

    NASA Technical Reports Server (NTRS)

    Carter, Edward L. (Inventor)

    1989-01-01

    The driving (30) and driven (32) members of a magnetic drive (20) are separated by an enlarged gap (35) to provide clearance for a conduit (23) or other member. Flux pins (40) in the gap (35) maintain the torque transmitting capability of the drive (20). The spacing between two of the flux pins is increased to provide space for the conduit (23).

  10. Sequential Dependencies in Driving

    ERIC Educational Resources Information Center

    Doshi, Anup; Tran, Cuong; Wilder, Matthew H.; Mozer, Michael C.; Trivedi, Mohan M.

    2012-01-01

    The effect of recent experience on current behavior has been studied extensively in simple laboratory tasks. We explore the nature of sequential effects in the more naturalistic setting of automobile driving. Driving is a safety-critical task in which delayed response times may have severe consequences. Using a realistic driving simulator, we find…

  11. Grieving while Driving

    ERIC Educational Resources Information Center

    Rosenblatt, Paul C.

    2004-01-01

    Secondary analysis of data from 84 people in 2 interview studies shows that some bereaved people grieve actively while driving. The grief can be intense, even years after a death. Grief while driving may erupt spontaneously or be set off by a wide range of reminders. Some bereaved people seem to save their grieving for times when they drive,…

  12. Demographic and Practice Characteristics of Psychiatrists who Primarily Treat Patients with Substance Use Disorders

    PubMed Central

    Montoya, Ivan D.; Herbeck, Diane M.; Svikis, Dace S.; Fitek, Diana J.; Marcus, Steven C.; Pincus, Harold A.

    2008-01-01

    This study examined the sociodemographic and practice characteristics of psychiatrists whose caseloads consist primarily of patients with Substance Use Disorders (SUD). A. survey instrument was completed by a random sample of 865 psychiatrists. Study groups were defined as high-SUD providers if psychiatrists reported having 51% or more patients with SUD (n = 92) and non-SUD providers as those who reported not having any patients with SUD (n = 128). High-SUD providers tended to be younger, more likely to graduate from international medical schools, have larger caseloads, work more hours per week, and have a higher proportion of inpatients and publicly funded patients than non-SUD providers. Results suggest that psychiatrists who primarily treat patients with SUD are in their early careers and treat patients with more clinical, psychosocial, and economic disadvantages. The implications of these findings for psychiatry training programs and policy makers will be discussed. PMID:12851014

  13. Pharmacometric Approaches to Personalize Use of Primarily Renally Eliminated Antibiotics in Preterm and Term Neonates.

    PubMed

    Wilbaux, Mélanie; Fuchs, Aline; Samardzic, Janko; Rodieux, Frédérique; Csajka, Chantal; Allegaert, Karel; van den Anker, Johannes N; Pfister, Marc

    2016-08-01

    Sepsis remains a major cause of mortality and morbidity in neonates, and, as a consequence, antibiotics are the most frequently prescribed drugs in this vulnerable patient population. Growth and dynamic maturation processes during the first weeks of life result in large inter- and intrasubject variability in the pharmacokinetics (PK) and pharmacodynamics (PD) of antibiotics. In this review we (1) summarize the available population PK data and models for primarily renally eliminated antibiotics, (2) discuss quantitative approaches to account for effects of growth and maturation processes on drug exposure and response, (3) evaluate current dose recommendations, and (4) identify opportunities to further optimize and personalize dosing strategies of these antibiotics in preterm and term neonates. Although population PK models have been developed for several of these drugs, exposure-response relationships of primarily renally eliminated antibiotics in these fragile infants are not well understood, monitoring strategies remain inconsistent, and consensus on optimal, personalized dosing of these drugs in these patients is absent. Tailored PK/PD studies and models are useful to better understand relationships between drug exposures and microbiological or clinical outcomes. Pharmacometric modeling and simulation approaches facilitate quantitative evaluation and optimization of treatment strategies. National and international collaborations and platforms are essential to standardize and harmonize not only studies and models but also monitoring and dosing strategies. Simple bedside decision tools assist clinical pharmacologists and neonatologists in their efforts to fine-tune and personalize the use of primarily renally eliminated antibiotics in term and preterm neonates. PMID:26766774

  14. Electric versus hydraulic drives

    SciTech Connect

    Not Available

    1983-01-01

    This volume records the proceedings of a conference organised by the Engineering Manufacturing Industries Division of the Institution of Mechanical Engineers. Topics considered include high performance position control - a review of the current state of developments; hydrostatic drives - present and future; electric drives - present and future trends; electrical and hydraulic drives for heavy industrial robots; the development of an electro-mechanical tilt system for the advanced passenger train; industrial hydraulic ring mains - effective or efficient. the comparison of performance of servo feed-drive systems; overhead crane drives; the future of d.c. servodrives; the choice of actuator for military systems; linear electro-hydraulic actuators; and actuation for industrial robots.

  15. Drill drive mechanism

    DOEpatents

    Dressel, Michael O.

    1979-01-01

    A drill drive mechanism is especially adapted to provide both rotational drive and axial feed for a drill of substantial diameter such as may be used for drilling holes for roof bolts in mine shafts. The drill shaft is made with a helical pattern of scroll-like projections on its surface for removal of cuttings. The drill drive mechanism includes a plurality of sprockets carrying two chains of drive links which are arranged to interlock around the drill shaft with each drive link having depressions which mate with the scroll-like projections. As the chain links move upwardly or downwardly the surfaces of the depressions in the links mate with the scroll projections to move the shaft axially. Tangs on the drive links mate with notch surfaces between scroll projections to provide a means for rotating the shaft. Projections on the drive links mate together at the center to hold the drive links tightly around the drill shaft. The entire chain drive mechanism is rotated around the drill shaft axis by means of a hydraulic motor and gear drive to cause rotation of the drill shaft. This gear drive also connects with a differential gearset which is interconnected with a second gear. A second motor is connected to the spider shaft of the differential gearset to produce differential movement (speeds) at the output gears of the differential gearset. This differential in speed is utilized to drive said second gear at a speed different from the speed of said gear drive, this speed differential being utilized to drive said sprockets for axial movement of said drill shaft.

  16. Sleep Patterns of a Primarily Obese Sample of Treatment-Seeking Children

    PubMed Central

    Graef, Danielle M.; Janicke, David M.; McCrae, Christina S.

    2014-01-01

    Study Objectives: To examine the sleep patterns and the role of day of the week and school break in these patterns within a primarily obese sample of children. Methods: Participants included 143 obese children (8-12 years) and their parents initiating treatment in a weight-management study in a community-based setting. Demographics, anthropometrics, and objectively measured sleep (i.e., with use of Sensewear Armbands) were collected prior to treatment. Results: Sleep duration was insufficient in our sample, as approximately 88% obtained less than 8 hours of sleep (mean = 6.92, standard deviation = 0.85). Those with lower total sleep time included older children, those identified as African American (compared to those identified as Caucasian), and those identified as Non-Hispanic (compared to those identified as Hispanic). Children on school break initiated sleep later than those in school the week of measurement. Children woke later on weekends and when on school break. There were no differences in day of the week or school break in predicting child sleep duration and total wake time (p's > 0.05). Conclusions: This study is one of the first to examine sleep patterns within a primarily obese sample of treatment-seeking rural children. There is a need for research to develop a better understanding of how sleep may affect health functioning and weight management, as well as quality of life and psychosocial functioning of children who are overweight or obese. Clinical Trials Information: Title of trial: Extension Family Lifestyle Intervention Project (E-FLIP for Kids). Clinical-Trials.gov identifier: NCT01820338. NIH/NIDDK Grant #: 1R18DK082374-01. Citation: Graef DM, Janicke DM, McCrae CS. Sleep patterns of a primarily obese sample of treatment-seeking children. J Clin Sleep Med 2014;10(10):1111-1117. PMID:25317092

  17. Magnetostrictive roller drive motor

    NASA Astrophysics Data System (ADS)

    Vranish, John M.

    1992-01-01

    A magnetostrictive drive motor is disclosed which has a rotary drive shaft in the form of a drum which is encircled by a plurality of substantially equally spaced roller members in the form of two sets of cones which are in contact with the respective cam surfaces on the inside surface of an outer drive ring. The drive ring is attached to sets of opposing pairs of magnetostrictive rods. Each rod in a pair is mutually positioned end to end within respective energizing coils. When one of the coils in an opposing pair is energized, the energized rod expands while the other rod is caused to contract, causing the drive ring to rock, i.e., rotate slightly in either the clockwise or counterclockwise direction, depending upon which rod in a pair is energized. As the drive ring is activated in repetitive cycles in either direction, one set of drive cones attempts to roll up their respective cam surface but are pinned between the drive shaft drum and the drive ring. As the frictional force preventing sliding builds up, the cones become locked, setting up reaction forces including a tangential component which is imparted to the drive shaft drum to provide a source of motor torque. Simultaneously the other set of cones are disengaged from the drive shaft drum. Upon deactivation of the magnetostrictive rod coils, the force on the drive cones is released, causing the system to return to an initial rest position. By repetitively cycling the energization of the magnetostrictive rods, the drive shaft drum indexes in microradian rotational steps.

  18. A genomic timescale of prokaryote evolution: insights into the origin of methanogenesis, phototrophy, and the colonization of land

    NASA Technical Reports Server (NTRS)

    Battistuzzi, Fabia U.; Feijao, Andreia; Hedges, S. Blair

    2004-01-01

    BACKGROUND: The timescale of prokaryote evolution has been difficult to reconstruct because of a limited fossil record and complexities associated with molecular clocks and deep divergences. However, the relatively large number of genome sequences currently available has provided a better opportunity to control for potential biases such as horizontal gene transfer and rate differences among lineages. We assembled a data set of sequences from 32 proteins (approximately 7600 amino acids) common to 72 species and estimated phylogenetic relationships and divergence times with a local clock method. RESULTS: Our phylogenetic results support most of the currently recognized higher-level groupings of prokaryotes. Of particular interest is a well-supported group of three major lineages of eubacteria (Actinobacteria, Deinococcus, and Cyanobacteria) that we call Terrabacteria and associate with an early colonization of land. Divergence time estimates for the major groups of eubacteria are between 2.5-3.2 billion years ago (Ga) while those for archaebacteria are mostly between 3.1-4.1 Ga. The time estimates suggest a Hadean origin of life (prior to 4.1 Ga), an early origin of methanogenesis (3.8-4.1 Ga), an origin of anaerobic methanotrophy after 3.1 Ga, an origin of phototrophy prior to 3.2 Ga, an early colonization of land 2.8-3.1 Ga, and an origin of aerobic methanotrophy 2.5-2.8 Ga. CONCLUSIONS: Our early time estimates for methanogenesis support the consideration of methane, in addition to carbon dioxide, as a greenhouse gas responsible for the early warming of the Earths' surface. Our divergence times for the origin of anaerobic methanotrophy are compatible with highly depleted carbon isotopic values found in rocks dated 2.8-2.6 Ga. An early origin of phototrophy is consistent with the earliest bacterial mats and structures identified as stromatolites, but a 2.6 Ga origin of cyanobacteria suggests that those Archean structures, if biologically produced, were made by

  19. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... service operated by private entities not primarily engaged in the business of transporting people. 37.171... responsive service operated by private entities not primarily engaged in the business of transporting people. A private entity not primarily engaged in the business of transporting people which operates...

  20. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... service operated by private entities not primarily engaged in the business of transporting people. 37.171... responsive service operated by private entities not primarily engaged in the business of transporting people. A private entity not primarily engaged in the business of transporting people which operates...

  1. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... service operated by private entities not primarily engaged in the business of transporting people. 37.171... responsive service operated by private entities not primarily engaged in the business of transporting people. A private entity not primarily engaged in the business of transporting people which operates...

  2. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... service operated by private entities not primarily engaged in the business of transporting people. 37.171... responsive service operated by private entities not primarily engaged in the business of transporting people. A private entity not primarily engaged in the business of transporting people which operates...

  3. 49 CFR 37.107 - Acquisition of passenger rail cars by private entities primarily engaged in the business of...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... entities primarily engaged in the business of transporting people. 37.107 Section 37.107 Transportation... entities primarily engaged in the business of transporting people. (a) A private entity which is primarily engaged in the business of transporting people and whose operations affect commerce, which makes...

  4. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... service operated by private entities not primarily engaged in the business of transporting people. 37.171... responsive service operated by private entities not primarily engaged in the business of transporting people. A private entity not primarily engaged in the business of transporting people which operates...

  5. Decisive Data Sets in Phylogenomics: Lessons from Studies on the Phylogenetic Relationships of Primarily Wingless Insects

    PubMed Central

    Meusemann, Karen; Meyer, Benjamin; Borner, Janus; Petersen, Malte; Aberer, Andre J.; Stamatakis, Alexandros; Walzl, Manfred G.; Minh, Bui Quang; von Haeseler, Arndt; Ebersberger, Ingo; Pass, Günther; Misof, Bernhard

    2014-01-01

    Phylogenetic relationships of the primarily wingless insects are still considered unresolved. Even the most comprehensive phylogenomic studies that addressed this question did not yield congruent results. To get a grip on these problems, we here analyzed the sources of incongruence in these phylogenomic studies by using an extended transcriptome data set. Our analyses showed that unevenly distributed missing data can be severely misleading by inflating node support despite the absence of phylogenetic signal. In consequence, only decisive data sets should be used which exclusively comprise data blocks containing all taxa whose relationships are addressed. Additionally, we used Four-cluster Likelihood Mapping (FcLM) to measure the degree of congruence among genes of a data set, as a measure of support alternative to bootstrap. FcLM showed incongruent signal among genes, which in our case is correlated neither with functional class assignment of these genes nor with model misspecification due to unpartitioned analyses. The herein analyzed data set is the currently largest data set covering primarily wingless insects, but failed to elucidate their interordinal phylogenetic relationships. Although this is unsatisfying from a phylogenetic perspective, we try to show that the analyses of structure and signal within phylogenomic data can protect us from biased phylogenetic inferences due to analytical artifacts. PMID:24140757

  6. Superluminal warp drive

    NASA Astrophysics Data System (ADS)

    González-Díaz, Pedro F.

    2007-09-01

    In this Letter we consider a warp drive spacetime resulting from that suggested by Alcubierre when the spaceship can only travel faster than light. Restricting to the two dimensions that retains most of the physics, we derive the thermodynamic properties of the warp drive and show that the temperature of the spaceship rises up as its apparent velocity increases. We also find that the warp drive spacetime can be exhibited in a manifestly cosmological form.

  7. Effects and mode of action of chitosan and ivy fruit saponins on the microbiome, fermentation and methanogenesis in the rumen simulation technique.

    PubMed

    Belanche, Alejandro; Pinloche, Eric; Preskett, David; Newbold, C Jamie

    2016-01-01

    This study investigates the effects of supplementing a control diet (CON) with chitosan (CHI) or ivy fruit saponins (IVY) as natural feed additives. Both additives had similar abilities to decrease rumen methanogenesis (-42% and -40%, respectively) using different mechanisms: due to its antimicrobial and nutritional properties CHI promoted a shift in the fermentation pattern towards propionate production which explained about two thirds of the decrease in methanogenesis. This shift was achieved by a simplification of the structure in the bacterial community and a substitution of fibrolytic (Firmicutes and Fibrobacteres) by amylolytic bacteria (Bacteroidetes and Proteobacteria) which led to greater amylase activity, lactate and microbial protein yield with no detrimental effect on feed digestibility. Contrarily, IVY had negligible nutritional properties promoting minor changes in the fermentation pattern and on the bacterial community. Instead, IVY modified the structure of the methanogen community and decreased its diversity. This specific antimicrobial effect of IVY against methanogens was considered its main antimethanogenic mechanism. IVY had however a negative impact on microbial protein synthesis. Therefore, CHI and IVY should be further investigated in vivo to determine the optimum doses which maintain low methanogenesis but prevent negative effects on the rumen fermentation and animal metabolism. PMID:26676056

  8. Diabetes and driving.

    PubMed

    Inkster, B; Frier, B M

    2013-09-01

    The principal safety concern for driving for people treated with insulin or insulin secretagogues is hypoglycaemia, which impairs driving performance. Other complications, such as those causing visual impairment and peripheral neuropathy, are also relevant to medical fitness to drive. Case control studies have suggested that drivers with diabetes pose a modestly increased but acceptable and measurable risk of motor vehicle accidents compared to non-diabetic drivers, but many studies are limited and of poor quality. Factors which have been shown to increase driving risk include previous episodes of severe hypoglycaemia, previous hypoglycaemia while driving, strict glycaemic control (lower HbA1c) and absence of blood glucose monitoring before driving. Impaired awareness of hypoglycaemia may be counteracted by frequent blood glucose testing. The European Union Third directive on driving (2006) has necessitated changes in statutory regulations for driving licences for people with diabetes in all European States, including the UK. Stricter criteria have been introduced for Group 1 vehicle licences while those for Group 2 licences have been relaxed. Insulin-treated drivers can now apply to drive Group 2 vehicles, but in the UK must meet very strict criteria and be assessed by an independent specialist to be issued with a 1-year licence. PMID:23350766

  9. Involvement of the "A" isozyme of methyltransferase II and the 29-kilodalton corrinoid protein in methanogenesis from monomethylamine.

    PubMed Central

    Burke, S A; Krzycki, J A

    1995-01-01

    An assay which allowed detection of proteins involved in the trimethylamine- or monomethylamine (MMA)-dependent methylation of coenzyme M (CoM) was developed. The two activities could be separated by anion-exchange chromatography. The unresolved activity responsible for MMA:CoM methyl transfer eluted from a gel permeation column in the molecular mass range of 32 kDa. The activity was purified to two monomeric proteins of 40 and 29 kDa. The preparation contained protein-bound corrinoid in a mixture of Co(II) and Co(III) states, as well as methyl-B12:CoM methyltransferase (MT2) activity. N-terminal sequence analysis demonstrated that the polypeptides were two previously identified proteins of undefined physiological function. The smaller polypeptide was the monomeric 29-kDa corrinoid protein. The larger polypeptide was the "A" isozyme of MT2. Individually purified preparations of both proteins increased the rate of MMA-dependent CoM methylation by approximately 1.7 mumol/min/mg of purified protein above background activity in the extract of methanol-grown cells. These results indicate that the 29-kDa corrinoid protein and the "A" isozyme of MT2 function in methanogenesis from MMA. A likely mechanism is that the 29-kDa corrinoid is methylated by MMA and the methyl group is then transferred by the "A" isozyme of MT2 to CoM. PMID:7635826

  10. Conversion of Cn-Unsaturated into Cn-2-Saturated LCFA Can Occur Uncoupled from Methanogenesis in Anaerobic Bioreactors.

    PubMed

    Cavaleiro, Ana J; Pereira, Maria Alcina; Guedes, Ana P; Stams, Alfons J M; Alves, M Madalena; Sousa, Diana Z

    2016-03-15

    Fat, oils, and grease present in complex wastewater can be readily converted to methane, but the energy potential of these compounds is not always recyclable, due to incomplete degradation of long chain fatty acids (LCFA) released during lipids hydrolysis. Oleate (C18:1) is generally the dominant LCFA in lipid-containing wastewater, and its conversion in anaerobic bioreactors results in palmitate (C16:0) accumulation. The reason why oleate is continuously converted to palmitate without further degradation via β-oxidation is still unknown. In this work, the influence of methanogenic activity in the initial conversion steps of unsaturated LCFA was studied in 10 bioreactors continuously operated with saturated or unsaturated C16- and C18-LCFA, in the presence or absence of the methanogenic inhibitor bromoethanesulfonate (BrES). Saturated Cn-2-LCFA accumulated both in the presence and absence of BrES during the degradation of unsaturated Cn-LCFA, and represented more than 50% of total LCFA. In the presence of BrES further conversion of saturated intermediates did not proceed, not even when prolonged batch incubation was applied. As the initial steps of unsaturated LCFA degradation proceed uncoupled from methanogenesis, accumulation of saturated LCFA can be expected. Analysis of the active microbial communities suggests a role for facultative anaerobic bacteria in the initial steps of unsaturated LCFA biodegradation. Understanding this role is now imperative to optimize methane production from LCFA. PMID:26810160

  11. Dependence on membrane components of methanogenesis from methyl-CoM with formaldehyde or molecular hydrogen as electron donors.

    PubMed

    Deppenmeier, U; Blaut, M; Gottschalk, G

    1989-12-01

    Methane formation from 2-(methylthio)-ethanesulfonate (methyl-CoM) and H2 by the soluble fraction from the methanogenic bacterium strain Gö1 was stimulated up to tenfold by the addition of the membrane fraction. This stimulation was observed with membranes from various methanogenic species belonging to different phylogenetic families, but not with membranes from Escherichia coli or Acetobacterium woodii. Treatment of the membranes with strong oxidants, i.e. O2 and K3[Fe(CN)6], or with SH reagents, i.e. Ag+, p-chloromercuribenzoate or iodoacetamide, caused an irreversible decrease or loss in stimulatory activity, as did heat treatment at temperatures above 78 degrees C. Methanogenesis from methyl-CoM with formaldehyde instead of H2 as electron donor depended similarly on the membrane fraction. With membranes, 1 mol HCHO was oxidized to 1 mol CO2 and allowed the formation of 2 mol CH4 from 2 mol CH3-CoM. Without membranes, per mol of HCHO oxidized 1 mol H2 was formed and 1 mol CH4 was produced from CH3-CoM; the rate was 10-20% of that in the presence of membranes. When methyl-CoM was replaced by an artificial electron acceptor system consisting of methylviologen and metronidazole, the formaldehyde-oxidizing activity was no longer stimulated by the membrane fraction. These results demonstrate for the first time an essential function of membrane components in methanogenic electron transfer. PMID:2513188

  12. N170 Changes Show Identifiable Chinese Characters Compete Primarily with Faces Rather than Houses

    PubMed Central

    Fan, Cong; He, Weiqi; He, Huamin; Ren, Guofang; Luo, Yuejia; Li, Hong; Luo, Wenbo

    2016-01-01

    Character processing is a crucial cognitive skill that is highly emphasized and industriously cultivated in contemporary society. In the present study, using a competition paradigm, we examined the electrophysiological correlates of different relationships between Chinese characters and faces and between Chinese characters and houses during early visual processing. We observed that identifiable Chinese characters compete primarily with faces rather than houses at an early visual processing stage, with a significantly reduced N170 for faces but not for houses, when they were viewed concurrently with identifiable characters relative to when they were viewed concurrently with unidentifiable characters. Consistent with our previous study, there was a significant increase in N170 after characters have been learned, indicating a modulatory effect of Chinese character identification level on N170 amplitude. Furthermore, we found an enlarged N170 in response to faces compared to houses, indicating that the neural mechanisms for processing faces and houses are different at an early visual processing stage. PMID:26779073

  13. Reading Text While Driving

    PubMed Central

    Horrey, William J.; Hoffman, Joshua D.

    2015-01-01

    Objective In this study, we investigated how drivers adapt secondary-task initiation and time-sharing behavior when faced with fluctuating driving demands. Background Reading text while driving is particularly detrimental; however, in real-world driving, drivers actively decide when to perform the task. Method In a test track experiment, participants were free to decide when to read messages while driving along a straight road consisting of an area with increased driving demands (demand zone) followed by an area with low demands. A message was made available shortly before the vehicle entered the demand zone. We manipulated the type of driving demands (baseline, narrow lane, pace clock, combined), message format (no message, paragraph, parsed), and the distance from the demand zone when the message was available (near, far). Results In all conditions, drivers started reading messages (drivers’ first glance to the display) before entering or before leaving the demand zone but tended to wait longer when faced with increased driving demands. While reading messages, drivers looked more or less off road, depending on types of driving demands. Conclusions For task initiation, drivers avoid transitions from low to high demands; however, they are not discouraged when driving demands are already elevated. Drivers adjust time-sharing behavior according to driving demands while performing secondary tasks. Nonetheless, such adjustment may be less effective when total demands are high. Application This study helps us to understand a driver’s role as an active controller in the context of distracted driving and provides insights for developing distraction interventions. PMID:25850162

  14. The Serotonin Transporter Undergoes Constitutive Internalization and Is Primarily Sorted to Late Endosomes and Lysosomal Degradation*

    PubMed Central

    Rahbek-Clemmensen, Troels; Bay, Tina; Eriksen, Jacob; Gether, Ulrik; Jørgensen, Trine Nygaard

    2014-01-01

    The serotonin transporter (SERT) plays a critical role in regulating serotonin signaling by mediating reuptake of serotonin from the extracellular space. The molecular and cellular mechanisms controlling SERT levels in the membrane remain poorly understood. To study trafficking of the surface resident SERT, two functional epitope-tagged variants were generated. Fusion of a FLAG-tagged one-transmembrane segment protein Tac to the SERT N terminus generated a transporter with an extracellular epitope suited for trafficking studies (TacSERT). Likewise, a construct with an extracellular antibody epitope was generated by introducing an HA (hemagglutinin) tag in the extracellular loop 2 of SERT (HA-SERT). By using TacSERT and HA-SERT in antibody-based internalization assays, we show that SERT undergoes constitutive internalization in a dynamin-dependent manner. Confocal images of constitutively internalized SERT demonstrated that SERT primarily co-localized with the late endosomal/lysosomal marker Rab7, whereas little co-localization was observed with the Rab11, a marker of the “long loop” recycling pathway. This sorting pattern was distinct from that of a prototypical recycling membrane protein, the β2-adrenergic receptor. Furthermore, internalized SERT co-localized with the lysosomal marker LysoTracker and not with transferrin. The sorting pattern was further confirmed by visualizing internalization of SERT using the fluorescent cocaine analog JHC1-64 and by reversible and pulse-chase biotinylation assays showing evidence for lysosomal degradation of the internalized transporter. Finally, we found that SERT internalized in response to stimulation with 12-myristate 13-acetate co-localized primarily with Rab7- and LysoTracker-positive compartments. We conclude that SERT is constitutively internalized and that the internalized transporter is sorted mainly to degradation. PMID:24973209

  15. Is urea formation regulated primarily by acid-base balance in vivo?

    PubMed

    Halperin, M L; Chen, C B; Cheema-Dhadli, S; West, M L; Jungas, R L

    1986-04-01

    Large quantities of ammonium and bicarbonate are produced each day from the metabolism of dietary protein. It has recently been proposed that urea synthesis is regulated by the need to remove this large load of bicarbonate. The purpose of these experiments was to test whether the primary function of ureagenesis in vivo is to remove ammonium or bicarbonate. The first series of rats were given a constant acid load as hydrochloric acid or ammonium chloride; individual rats received a constant nitrogen load at a time when their plasma acid-base status ranged from normal (pH 7.4, 28 mM HCO3) to severe metabolic acidosis (pH 6.9, 6 mM HCO3). Urea plus ammonium excretions and the blood urea, glutamine, and ammonium concentrations were monitored with time. Within the constraints of non-steady-state conditions, the rate of urea synthesis was constant and the plasma glutamine and ammonium concentrations also remained constant; thus it appears that the rate of urea synthesis was not primarily regulated by the acid-base status of the animal in vivo over a wide range of plasma ammonium concentrations. In quantitative terms, the vast bulk of the ammonium load was converted to urea over 80 min; only a small quantity of ammonium appeared as circulating glutamine or urinary ammonium. Urea synthesis was proportional to the nitrogen load. A second series of rats received sodium bicarbonate; urea synthesis was not augmented by a bicarbonate load. We conclude from these studies that the need to dispose of excess bicarbonate does not primarily determine the rate of ureagenesis in vivo. The data support the classical view that ureagenesis is controlled by the quantity of ammonium to be removed. PMID:3083695

  16. Classical Photoreceptors Are Primarily Responsible for the Pupillary Light Reflex in Mouse

    PubMed Central

    Jain, Varsha; Srivastava, Ipsit; Palchaudhuri, Shriya; Goel, Manvi; Sinha-Mahapatra, Sumit K.; Dhingra, Narender K.

    2016-01-01

    Pupillary light reflex (PLR) is an important clinical tool to assess the integrity of visual pathways. The available evidence suggests that melanopsin-expressing retinal ganglion cells (mRGCs) mediate PLR—driven by the classical photoreceptors (rods and cones) at low irradiances and by melanopsin activation at high irradiances. However, genetic or pharmacological elimination of melanopsin does not completely abolish PLR at high irradiances, raising the possibility that classical photoreceptors may have a role even at high irradiances. Using an inducible mouse model of photoreceptor degeneration, we asked whether classical photoreceptors are responsible for PLR at all irradiances, and found that the PLR was severely attenuated at all irradiances. Using multiple approaches, we show that the residual PLR at high irradiances in this mouse was primarily from the remnant rods and cones, with a minor contribution from melanopsin activation. In contrast, in rd1 mouse where classical photoreceptor degeneration occurs during development, the PLR was absent at low irradiances but intact at high irradiances, as reported previously. Since mRGCs receive inputs from classical photoreceptors, we also asked whether developmental loss of classical photoreceptors as in rd1 mouse leads to compensatory takeover of the high-irradiance PLR by mRGCs. Specifically, we looked at a distinct subpopulation of mRGCs that express Brn3b transcription factor, which has been shown to mediate PLR. We found that rd1 mouse had a significantly higher proportion of Brn3b-expressing M1 type of mRGCs than in the inducible model. Interestingly, inducing classical photoreceptor degeneration during development also resulted in a higher proportion of Brn3b-expressing M1 cells and partially rescued PLR at high irradiances. These results suggest that classical photoreceptors are primarily responsible for PLR at all irradiances, while melanopsin activation makes a minor contribution at very high irradiances

  17. Hydrogen and carbon isotope systematics in hydrogenotrophic methanogenesis under H2-limited and H2-enriched conditions: implications for the origin of methane and its isotopic diagnosis

    NASA Astrophysics Data System (ADS)

    Okumura, Tomoyo; Kawagucci, Shinsuke; Saito, Yayoi; Matsui, Yohei; Takai, Ken; Imachi, Hiroyuki

    2016-12-01

    Hydrogen and carbon isotope systematics of H2O-H2-CO2-CH4 in hydrogenotrophic methanogenesis and their relation to H2 availability were investigated. Two H2-syntrophic cocultures of fermentatively hydrogenogenic bacteria and hydrogenotrophic methanogens under conditions of <102 Pa-H2 and two pure cultures of hydrogenotrophic methanogens under conditions of 105 Pa-H2 were tested. Carbon isotope fractionation between CH4 and CO2 during hydrogenotrophic methanogenesis was correlated with pH2, as indicated in previous studies. The hydrogen isotope ratio of CH4 produced during rapid growth of the thermophilic methanogen Methanothermococcus okinawensis under high pH2 conditions ( 105 Pa) was affected by the isotopic composition of H2, as concluded in a previous study of Methanothermobacter thermautotrophicus. This " {δ D}_{{H}_2} effect" is a possible cause of the diversity of previously reported values for hydrogen isotope fractionation between CH4 and H2O examined in H2-enriched culture experiments. Hydrogen isotope fractionation between CH4 and H2O, defined by (1000 + {δ D}_{{CH}_4} )/(1000 + {δ D}_{{H}_2O} ), during hydrogenotrophic methanogenesis of the H2-syntrophic cocultures was in the range 0.67-0.69. The hydrogen isotope fractionation of our H2-syntrophic dataset overlaps with those obtained not only from low- pH2 experiments reported so far but also from natural samples of "young" methane reservoirs (0.66-0.74). Conversely, such hydrogen isotope fractionation is not consistent with that of "aged" methane in geological samples (≥0.79), which has been regarded as methane produced via hydrogenotrophic methanogenesis from the carbon isotope fractionation. As a possible process inducing the inconsistency in hydrogen isotope signatures between experiments and geological samples, we hypothesize that the hydrogen isotope signature of CH4 imprinted at the time of methanogenesis, as in the experiments and natural young methane, may be altered by diagenetic hydrogen

  18. Piezoelectric drive circuit

    DOEpatents

    Treu, C.A. Jr.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes. 7 figs.

  19. Piezoelectric drive circuit

    DOEpatents

    Treu, Jr., Charles A.

    1999-08-31

    A piezoelectric motor drive circuit is provided which utilizes the piezoelectric elements as oscillators and a Meacham half-bridge approach to develop feedback from the motor ground circuit to produce a signal to drive amplifiers to power the motor. The circuit automatically compensates for shifts in harmonic frequency of the piezoelectric elements due to pressure and temperature changes.

  20. Dual drive actuators

    NASA Technical Reports Server (NTRS)

    Packard, D. T.

    1982-01-01

    A new class of electromechanical actuators is described. These dual drive actuators were developed for the NASA-JPL Galileo Spacecraft. The dual drive actuators are fully redundant and therefore have high inherent reliability. They can be used for a variety of tasks, and they can be fabricated quickly and economically.

  1. Design of traction drives

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Zaretsky, E. V.

    1985-01-01

    Traction drives are among the simplest of all speed-changing mechanisms. Because of their simplicity and their ability to smoothly and continuously adjust speed, they are excellent choices for many drive system applications. They have been used in industrial service for more than 100 years. Today's traction drives have power capacities which rival the best gear and belt drives due to modern traction fluids and highly fatigue-resistant bearing steels. This report summarizes methods to analyze and size traction drives. Lubrication principles, contact kinematics, stress, fatigue life, and performance prediction methods are presented. The effects of the lubricant's traction characteristics on life and power loss are discussed. An example problem is given which illustrates the effects of spin on power loss. Loading mechanism design and the design of nonlubricated friction wheels and rings are also treated.

  2. Habitat-specific environmental conditions primarily control the microbiomes of the coral Seriatopora hystrix.

    PubMed

    Pantos, Olga; Bongaerts, Pim; Dennis, Paul G; Tyson, Gene W; Hoegh-Guldberg, Ove

    2015-09-01

    Reef-building corals form complex relationships with a range of microorganisms including bacteria, archaea, fungi and the unicellular microalgae of the genus Symbiodinium, which together form the coral holobiont. These symbionts are known to have both beneficial and deleterious effects on their coral host, but little is known about what the governing factors of these relationships are, or the interactions that exist between the different members of the holobiont and their environment. Here we used 16S ribosomal RNA gene amplicon sequencing to investigate how archaeal and bacterial communities associated with the widespread scleractinian coral Seriatopora hystrix are influenced by extrinsic (reef habitat and geographic location) and intrinsic (host genotype and Symbiodinium subclade) factors. Bacteria dominate the microbiome of S. hystrix, with members of the Alphaproteobacteria, Gammaproteobacteria and Bacteriodetes being the most predominant in all samples. The richness and evenness of these communities varied between reef habitats, but there was no significant difference between distinct coral host lineages or corals hosting distinct Symbiodinium subclades. The coral microbiomes correlated to reef habitat (depth) and geographic location, with a negative correlation between Alpha- and Gammaproteobacteria, driven by the key members of both groups (Rhodobacteraceae and Hahellaceae, respectively), which showed significant differences between location and depth. This study suggests that the control of microbial communities associated with the scleractinian coral S. hystrix is driven primarily by external environmental conditions rather than by those directly associated with the coral holobiont. PMID:25668159

  3. Dehaloperoxidase-Hemoglobin from Amphitrite ornata Is Primarily a Monomer in Solution

    SciTech Connect

    M Thompson; S Franzen; M Davis; R Oliver; j Krueger; J Tredup; C Chang; J Khan; E Baldwin

    2011-12-31

    The crystal structures of the dehaloperoxidase-hemoglobin from A. ornata (DHP A) each report a crystallographic dimer in the unit cell. Yet, the largest dimer interface observed is 450 {angstrom}{sup 2}, an area significantly smaller than the typical value of 1200-2000 {angstrom}{sup 2} and in contrast to the extensive interface region of other known dimeric hemoglobins. To examine the oligomerization state of DHP A in solution, we used gel permeation by fast protein liquid chromatography and small-angle X-ray scattering (SAXS). Gel permeation experiments demonstrate that DHP A elutes as a monomer (15.5 kDa) and can be separated from green fluorescent protein, which has a molar mass of 27 kDa, near the 31 kDa expected for the DHP A dimer. By SAXS, we found that DHP A is primarily monomeric in solution, but with a detectable level of dimer (10%), under all conditions studied up to a protein concentration of 3.0 mM. These concentrations are likely 10-100-fold lower than the K{sub d} for dimer formation. Additionally, there was no significant effect either on the overall conformation of DHP A or its monomer-dimer equilibrium upon addition of the DHP A inhibitor, 4-iodophenol.

  4. Habitat-specific environmental conditions primarily control the microbiomes of the coral Seriatopora hystrix

    PubMed Central

    Pantos, Olga; Bongaerts, Pim; Dennis, Paul G; Tyson, Gene W; Hoegh-Guldberg, Ove

    2015-01-01

    Reef-building corals form complex relationships with a range of microorganisms including bacteria, archaea, fungi and the unicellular microalgae of the genus Symbiodinium, which together form the coral holobiont. These symbionts are known to have both beneficial and deleterious effects on their coral host, but little is known about what the governing factors of these relationships are, or the interactions that exist between the different members of the holobiont and their environment. Here we used 16S ribosomal RNA gene amplicon sequencing to investigate how archaeal and bacterial communities associated with the widespread scleractinian coral Seriatopora hystrix are influenced by extrinsic (reef habitat and geographic location) and intrinsic (host genotype and Symbiodinium subclade) factors. Bacteria dominate the microbiome of S. hystrix, with members of the Alphaproteobacteria, Gammaproteobacteria and Bacteriodetes being the most predominant in all samples. The richness and evenness of these communities varied between reef habitats, but there was no significant difference between distinct coral host lineages or corals hosting distinct Symbiodinium subclades. The coral microbiomes correlated to reef habitat (depth) and geographic location, with a negative correlation between Alpha- and Gammaproteobacteria, driven by the key members of both groups (Rhodobacteraceae and Hahellaceae, respectively), which showed significant differences between location and depth. This study suggests that the control of microbial communities associated with the scleractinian coral S. hystrix is driven primarily by external environmental conditions rather than by those directly associated with the coral holobiont. PMID:25668159

  5. Identification of a novel CoA synthase isoform, which is primarily expressed in Brain

    SciTech Connect

    Nemazanyy, Ivan . E-mail: nemazanyy@imbg.org.ua; Panasyuk, Ganna; Breus, Oksana; Zhyvoloup, Alexander; Filonenko, Valeriy; Gout, Ivan T. . E-mail: i.gout@ucl.ac.uk

    2006-03-24

    CoA and its derivatives Acetyl-CoA and Acyl-CoA are important players in cellular metabolism and signal transduction. CoA synthase is a bifunctional enzyme which mediates the final stages of CoA biosynthesis. In previous studies, we have reported molecular cloning, biochemical characterization, and subcellular localization of CoA synthase (CoASy). Here, we describe the existence of a novel CoA synthase isoform, which is the product of alternative splicing and possesses a 29aa extension at the N-terminus. We termed it CoASy {beta} and originally identified CoA synthase, CoASy {alpha}. The transcript specific for CoASy {beta} was identified by electronic screening and by RT-PCR analysis of various rat tissues. The existence of this novel isoform was further confirmed by immunoblot analysis with antibodies directed to the N-terminal peptide of CoASy {beta}. In contrast to CoASy {alpha}, which shows ubiquitous expression, CoASy {beta} is primarily expressed in Brain. Using confocal microscopy, we demonstrated that both isoforms are localized on mitochondria. The N-terminal extension does not affect the activity of CoA synthase, but possesses a proline-rich sequence which can bring the enzyme into complexes with signalling proteins containing SH3 or WW domains. The role of this novel isoform in CoA biosynthesis, especially in Brain, requires further elucidation.

  6. The integrated dayside merging rate is controlled primarily by the solar wind

    NASA Astrophysics Data System (ADS)

    Lopez, Ramon E.

    2016-05-01

    An argument is presented to support the view that the rate of merging between the geomagnetic field and the interplanetary magnetic field across the dayside magnetosphere is controlled primarily by the solar wind parameters. The controlling parameters are the solar wind electric field in the Earth's frame of reference and the solar wind magnetosonic fast mode Mach number. These factors control to first order the total amount of magnetic flux that is carried by the magnetosheath flow to the dayside merging region. We argue that the global dayside merging rate is governed by the amount of flux that is delivered to the dayside merging line by the magnetosheath flow. The ionospheric conductance also plays an important role by modulating the shape of the magnetospheric obstacle around which the magnetosheath flow is deflected. The local conditions at the magnetopause, especially changes in magnetospheric plasma density will affect the local reconnection rate, but not the global dayside merging rate because to change the global merging rate the entire pattern of magnetosheath flow must be changed. The conceptual model presented here can explain how dayside merging depends on solar wind values, including both linear and nonlinear dependencies, through the application of a single, unifying perspective, without the need for ad hoc mechanisms that limit the dayside merging rate.

  7. Floral biology of two Vanilloideae (Orchidaceae) primarily adapted to pollination by euglossine bees.

    PubMed

    Pansarin, E R; Pansarin, L M

    2014-11-01

    Vanilloideae comprises 15 genera distributed worldwide, among which are Vanilla and Epistephium (tribe Vanilleae). Based on field and laboratory investigations, the pollination biology of V. dubia and E. sclerophyllum was analysed. The former was surveyed in a semi-deciduous mesophytic forest at the biological reserve of Serra do Japi and in a marshy forest at the city of Pradópolis, southeastern Brazil. The latter was examined in rocky outcrop vegetation in the Chapada Diamantina, northeastern Brazil. In the studied populations, the tubular flowers of V. dubia and E. sclerophyllum were pollinated by bees. Pollen was deposited on either their scutellum (V. dubia) or scutum (E. sclerophyllum). The mentum region of V. dubia is dry, whereas that of E. sclerophyllum presents a small quantity of dilute nectar. Flowers of E. sclerophyllum are scentless, while those of V. dubia are odoriferous. Although V. dubia is self-compatible, it needs a pollinator to produce fruit. In contrast, E. sclerophyllum sets fruit through spontaneous self-pollination, but biotic pollination also occurs. Both species are primarily adapted to pollination by euglossine bees. Pollination by Euglossina seems to have occurred at least twice during the evolution of Vanilleae. Furthermore, shifts between rewarding and reward-free flowers and between autogamous and allogamous species have been reported among vanillas. PMID:24739080

  8. Dehaloperoxidase-hemoglobin from Amphitrite ornata is primarily a monomer in solution.

    PubMed

    Thompson, Matthew K; Franzen, Stefan; Davis, Michael F; Oliver, Ryan C; Krueger, Joanna K

    2011-04-14

    The crystal structures of the dehaloperoxidase-hemoglobin from A. ornata (DHP A) each report a crystallographic dimer in the unit cell. Yet, the largest dimer interface observed is 450 Å(2), an area significantly smaller than the typical value of 1200-2000 Å(2) and in contrast to the extensive interface region of other known dimeric hemoglobins. To examine the oligomerization state of DHP A in solution, we used gel permeation by fast protein liquid chromatography and small-angle X-ray scattering (SAXS). Gel permeation experiments demonstrate that DHP A elutes as a monomer (15.5 kDa) and can be separated from green fluorescent protein, which has a molar mass of 27 kDa, near the 31 kDa expected for the DHP A dimer. By SAXS, we found that DHP A is primarily monomeric in solution, but with a detectable level of dimer (~10%), under all conditions studied up to a protein concentration of 3.0 mM. These concentrations are likely 10-100-fold lower than the K(d) for dimer formation. Additionally, there was no significant effect either on the overall conformation of DHP A or its monomer-dimer equilibrium upon addition of the DHP A inhibitor, 4-iodophenol. PMID:21417234

  9. Vision and Driving

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald

    2010-01-01

    Driving is the primary means of personal travel in many countries and is relies heavily on vision for its successful execution. Research over the past few decades has addressed the role of vision in driver safety (motor vehicle collision involvement) and in driver performance (both on-road and using interactive simulators in the laboratory). Here we critically review what is currently known about the role of various aspects of visual function in driving. We also discuss translational research issues on vision screening for licensure and re-licensure and rehabilitation of visually impaired persons who want to drive. PMID:20580907

  10. Redundant motor drive system

    NASA Technical Reports Server (NTRS)

    Calvert, J. A. (Inventor)

    1980-01-01

    A drive system characterized by a base supporting a pair of pillars arranged in spaced parallelism, a shaft extended between and supported by the pillars for rotation about the longitudinal axis thereof, a worm gear affixed to the shaft and supported in coaxial relation therewith is described. A bearing housing of a sleeve like configuration is concentrically related to the shaft and is supported thereby for free rotation. A first and a second quiescent drive train, alternatively activatable, is provided for imparting rotation into said bearing housing. Each of the drive trains is characterized by a selectively energizable motor connected to a spur gear.

  11. The Test Drive

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken at NASA's Jet Propulsion Laboratory shows engineers rehearsing the sol 133 (June 8, 2004) drive into 'Endurance' crater by NASA's Mars Exploration Rover Opportunity. Engineers and scientists have recreated the martian surface and slope the rover will encounter using a combination of bare and thinly sand-coated rocks, simulated martian 'blueberries' and a platform tilted at a 25-degree angle. The results of this test convinced engineers that the rover was capable of driving up and down a straight slope before it attempted the actual drive on Mars.

  12. Visually Impaired Drivers Who Use Bioptic Telescopes: Self-Assessed Driving Skills and Agreement With On-Road Driving Evaluation

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald; Elgin, Jennifer; Wood, Joanne M.

    2014-01-01

    Purpose. To compare self-assessed driving habits and skills of licensed drivers with central visual loss who use bioptic telescopes to those of age-matched normally sighted drivers, and to examine the association between bioptic drivers' impressions of the quality of their driving and ratings by a “backseat” evaluator. Methods. Participants were licensed bioptic drivers (n = 23) and age-matched normally sighted drivers (n = 23). A questionnaire was administered addressing driving difficulty, space, quality, exposure, and, for bioptic drivers, whether the telescope was helpful in on-road situations. Visual acuity and contrast sensitivity were assessed. Information on ocular diagnosis, telescope characteristics, and bioptic driving experience was collected from the medical record or in interview. On-road driving performance in regular traffic conditions was rated independently by two evaluators. Results. Like normally sighted drivers, bioptic drivers reported no or little difficulty in many driving situations (e.g., left turns, rush hour), but reported more difficulty under poor visibility conditions and in unfamiliar areas (P < 0.05). Driving exposure was reduced in bioptic drivers (driving 250 miles per week on average vs. 410 miles per week for normally sighted drivers, P = 0.02), but driving space was similar to that of normally sighted drivers (P = 0.29). All but one bioptic driver used the telescope in at least one driving task, and 56% used the telescope in three or more tasks. Bioptic drivers' judgments about the quality of their driving were very similar to backseat evaluators' ratings. Conclusions. Bioptic drivers show insight into the overall quality of their driving and areas in which they experience driving difficulty. They report using the bioptic telescope while driving, contrary to previous claims that it is primarily used to pass the vision screening test at licensure. PMID:24370830

  13. Effects of Flavonoid-rich Plant Extracts on In vitro Ruminal Methanogenesis, Microbial Populations and Fermentation Characteristics.

    PubMed

    Kim, Eun T; Guan, Le Luo; Lee, Shin J; Lee, Sang M; Lee, Sang S; Lee, Il D; Lee, Su K; Lee, Sung S

    2015-04-01

    The objective of this study was to evaluate the in vitro effects of flavonoid-rich plant extracts (PE) on ruminal fermentation characteristics and methane emission by studying their effectiveness for methanogenesis in the rumen. A fistulated Holstein cow was used as a donor of rumen fluid. The PE (Punica granatum, Betula schmidtii, Ginkgo biloba, Camellia japonica, and Cudrania tricuspidata) known to have high concentrations of flavonoid were added to an in vitro fermentation incubated with rumen fluid. Total gas production and microbial growth with all PE was higher than that of the control at 24 h incubation, while the methane emission was significantly lower (p<0.05) than that of the control. The decrease in methane accumulation relative to the control was 47.6%, 39.6%, 46.7%, 47.9%, and 48.8% for Punica, Betula, Ginkgo, Camellia, and Cudrania treatments, respectively. Ciliate populations were reduced by more than 60% in flavonoid-rich PE treatments. The Fibrobacter succinogenes diversity in all added flavonoid-rich PE was shown to increase, while the Ruminoccocus albus and R. flavefaciens populations in all PE decreased as compared with the control. In particular, the F. succinogenes community with the addition of Birch extract increased to a greater extent than that of others. In conclusion, the results of this study showed that flavonoid-rich PE decreased ruminal methane emission without adversely affecting ruminal fermentation characteristics in vitro in 24 h incubation time, suggesting that the flavonoid-rich PE have potential possibility as bio-active regulator for ruminants. PMID:25656200

  14. Effects of Flavonoid-rich Plant Extracts on In vitro Ruminal Methanogenesis, Microbial Populations and Fermentation Characteristics

    PubMed Central

    Kim, Eun T.; Guan, Le Luo; Lee, Shin J.; Lee, Sang M.; Lee, Sang S.; Lee, Il D.; Lee, Su K.; Lee, Sung S.

    2015-01-01

    The objective of this study was to evaluate the in vitro effects of flavonoid-rich plant extracts (PE) on ruminal fermentation characteristics and methane emission by studying their effectiveness for methanogenesis in the rumen. A fistulated Holstein cow was used as a donor of rumen fluid. The PE (Punica granatum, Betula schmidtii, Ginkgo biloba, Camellia japonica, and Cudrania tricuspidata) known to have high concentrations of flavonoid were added to an in vitro fermentation incubated with rumen fluid. Total gas production and microbial growth with all PE was higher than that of the control at 24 h incubation, while the methane emission was significantly lower (p<0.05) than that of the control. The decrease in methane accumulation relative to the control was 47.6%, 39.6%, 46.7%, 47.9%, and 48.8% for Punica, Betula, Ginkgo, Camellia, and Cudrania treatments, respectively. Ciliate populations were reduced by more than 60% in flavonoid-rich PE treatments. The Fibrobacter succinogenes diversity in all added flavonoid-rich PE was shown to increase, while the Ruminoccocus albus and R. flavefaciens populations in all PE decreased as compared with the control. In particular, the F. succinogenes community with the addition of Birch extract increased to a greater extent than that of others. In conclusion, the results of this study showed that flavonoid-rich PE decreased ruminal methane emission without adversely affecting ruminal fermentation characteristics in vitro in 24 h incubation time, suggesting that the flavonoid-rich PE have potential possibility as bio-active regulator for ruminants. PMID:25656200

  15. Bleomycin, unlike other male-mouse mutagens, is most effective in spermatogonia, inducing primarily deletions.

    PubMed

    Russell, L B; Hunsicker, P R; Kerley, M K; Johnson, D K; Shelby, M D

    2000-08-21

    Dominant-lethal tests [P.D. Sudman, J.C. Rutledge, J.B. Bishop, W.M. Generoso, Bleomycin: female-specific dominant lethal effects in mice, Mutat. Res. 296 (1992) 205-217] had suggested that Bleomycin sulfate (Blenoxane), BLM, might be a female-specific mutagen. While confirming that BLM is indeed a powerful inducer of dominant-lethal mutations in females that fails to induce such mutations in postspermatogonial stages of males, we have shown in a specific-locus test that BLM is, in fact, mutagenic in males. This mutagenicity, however, is restricted to spermatogonia (stem-cell and differentiating stages), for which the specific-locus mutation rate differed significantly (P<0.008) from the historical control rate. In treated groups, dominant mutations, also, originated only in spermatogonia. With regard to mutation frequencies, this germ-cell-stage pattern is different from that for radiation and for any other chemical studied to date, except ethylnitrosourea (ENU). However, the nature of the spermatogonial specific-locus mutations differentiates BLM from ENU as well, because BLM induced primarily (or, perhaps, exclusively) multilocus deletions. Heretofore, no chemical that induced specific-locus mutations in spermatogonia did not also induce specific-locus as well as dominant-lethal mutations in postspermatogonial stages, making the dominant lethal test, up till now, predictive of male mutagenicity in general. The BLM results now demonstrate that there are chemicals that can induce specific-locus mutations in spermatogonia without testing positive in postspermatogonial stages. Thus, BLM, while not female-specific, is unique, (a) in its germ-cell-stage specificity in males, and (b) in inducing a type of mutation (deletions) that is atypical for the responding germ-cell stages (spermatogonia). PMID:10946246

  16. Species sorting and seasonal dynamics primarily shape bacterial communities in the Upper Mississippi River.

    PubMed

    Staley, Christopher; Gould, Trevor J; Wang, Ping; Phillips, Jane; Cotner, James B; Sadowsky, Michael J

    2015-02-01

    Bacterial community structure (BCS) in freshwater ecosystems varies seasonally and due to physicochemical gradients, but metacommunity structure of a major river remains understudied. Here we characterize the BCS along the Mississippi River and contributing rivers in Minnesota over three years using Illumina next-generation sequencing, to determine how changes in environmental conditions as well as inputs from surrounding land and confluences impacted community structure. Contributions of sediment to water microbial diversity were also evaluated. Long-term variation in community membership was observed, and significant shifts in relative abundances of major freshwater taxa, including α-Proteobacteria, Burkholderiales, and Actinomycetales, were observed due to temporal and spatial variations. Environmental parameters (e.g. temperature, rainfall, and nutrient concentrations) primarily contributed to differences in phyla abundances (88% of variance), with minimal influence from spatial distance alone (<1% of variance). Furthermore, an annually-recurrent BCS was observed in late summer, further suggesting that seasonal dynamics strongly influence community composition. Sediment communities differed from those in the water, but contributed up to 50% to community composition in the water column. Among water sampling sites, 34% showed significant variability in BCS of replicate samples indicating variability among riverine communities due to heterogeneity in the water column. Results of this study highlight the need for a better understanding of spatial and temporal variations in riverine bacterial diversity associated with physicochemical gradients and reveal how communities in sediments, and potentially other environmental reservoirs, impact waterborne BCS. Techniques used in this study may prove useful to determine sources of microbes from sediments and soils to waterways, which will facilitate best management practices and total maximum daily load determinations

  17. Brainstem structures are primarily affected in an experimental model of severe scorpion envenomation.

    PubMed

    Guidine, Patrícia Alves Maia; Cash, Diana; Drumond, Luciana Estefani; de Souza E Rezende, Gustavo Henrique; Massensini, André Ricardo; Williams, Steve Charles Rees; Moraes-Santos, Tasso; Moraes, Márcio Flávio Dutra; Mesquita, Michel Bernanos Soares

    2014-01-01

    Severe scorpion envenoming (SSE) is more frequent in children and is characterized by systemic dysfunctions with a mortality rate of up to 9%. Recent evidence shows that the central nervous system (CNS) plays a key role in triggering the cascade of symptoms present in SSE. The age-dependent role of the CNS in SSE lethality may be summarized in 3 hypotheses: (1) the shown increased blood brain barrier permeability of infants to the toxins would especially and primarily compromise neurovegetative control areas, (2) the neurons within these areas have high affinity to the toxins, and (3) the neurovascular interaction is such that SSE metabolically compromises proper function of toxin-targeted areas. A pharmacological magnetic resonance imaging paradigm was used to evaluate localized hemodynamic changes in relative cerebral blood volume (rCBV) for 30 min after the injection of TsTX, the most lethal toxin from the venom of the Tityus serrulatus scorpion. The brainstem showed significant rCBV reduction 1 min after TsTX administration, whereas rostral brain areas had delayed increase in rCBV (confirmed by laser Doppler measurements of cortical cerebral blood flow). Moreover, metabolic activity by 14C-2-deoxyglucose autoradiography showed the highest relative increase at the brainstem. To test whether TsTX has high affinity to brainstem neurons, the lateral ventricle was injected with Alexa Fluor 568 TsTX. Although some neurons showed intense fluorescence, the labeling pattern suggests that specific neurons were targeted. Altogether, these results suggest that brainstem areas involved in neurovegetative control are most likely within the primary structures triggering the cascade of symptoms present in SSE. PMID:24105889

  18. Dementia and driving

    MedlinePlus

    ... getting more dangerous include: Getting lost on familiar roads Reacting more slowly in traffic Driving too slowly ... attention to traffic signs Taking chances on the road Drifting into other lanes Getting more agitated in ...

  19. Control rod drive

    SciTech Connect

    Hawke, Basil C.

    1986-01-01

    A control rod drive uses gravitational forces to insert one or more control rods upwardly into a reactor core from beneath the reactor core under emergency conditions. The preferred control rod drive includes a vertically movable weight and a mechanism operatively associating the weight with the control rod so that downward movement of the weight is translated into upward movement of the control rod. The preferred control rod drive further includes an electric motor for driving the control rods under normal conditions, an electrically actuated clutch which automatically disengages the motor during a power failure and a decelerator for bringing the control rod to a controlled stop when it is inserted under emergency conditions into a reactor core.

  20. Drive program documentation

    NASA Technical Reports Server (NTRS)

    Graham, S.

    1979-01-01

    The program description and user's guide for the Downlist Requirement Integrated Verification and Evaluation (DRIVE) program is provided. The program is used to compare existing telemetry downlist files with updated downlist requirements.

  1. Safe driving for teens

    MedlinePlus

    ... drivers. Do not use cell phones for talking, texting, or email when you are driving. Mobile phones ... pull off of the road before answering or texting. Other tips include: Avoid putting on makeup while ...

  2. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett Lee; Danforth, William; Bevington, Christopher; Stowell, Jesse; Costin, Daniel

    2006-09-19

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  3. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Jesse, Stowell; Costin, Daniel

    2007-02-27

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  4. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Stowell, Jesse; Costin, Daniel

    2006-07-11

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  5. Direct drive wind turbine

    DOEpatents

    Bywaters, Garrett; Danforth, William; Bevington, Christopher; Jesse, Stowell; Costin, Daniel

    2006-10-10

    A wind turbine is provided that minimizes the size of the drive train and nacelle while maintaining the power electronics and transformer at the top of the tower. The turbine includes a direct drive generator having an integrated disk brake positioned radially inside the stator while minimizing the potential for contamination. The turbine further includes a means for mounting a transformer below the nacelle within the tower.

  6. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

    BS>A drive mechanism was invented for the control rod of a nuclear reactor. Power is provided by an electric motor and an outside source of fluid pressure is utilized in conjunction with the fluid pressure within the reactor to balance the loadings on the motor. The force exerted on the drive mechanism in the direction of scramming the rod is derived from the reactor fluid pressure so that failure of the outside pressure source will cause prompt scramming of the rod.

  7. Common drive unit

    NASA Technical Reports Server (NTRS)

    Ellis, R. C.; Fink, R. A.; Moore, E. A.

    1987-01-01

    The Common Drive Unit (CDU) is a high reliability rotary actuator with many versatile applications in mechanism designs. The CDU incorporates a set of redundant motor-brake assemblies driving a single output shaft through differential. Tachometers provide speed information in the AC version. Operation of both motors, as compared to the operation of one motor, will yield the same output torque with twice the output speed.

  8. Self-driving carsickness.

    PubMed

    Diels, Cyriel; Bos, Jelte E

    2016-03-01

    This paper discusses the predicted increase in the occurrence and severity of motion sickness in self-driving cars. Self-driving cars have the potential to lead to significant benefits. From the driver's perspective, the direct benefits of this technology are considered increased comfort and productivity. However, we here show that the envisaged scenarios all lead to an increased risk of motion sickness. As such, the benefits this technology is assumed to bring may not be capitalised on, in particular by those already susceptible to motion sickness. This can negatively affect user acceptance and uptake and, in turn, limit the potential socioeconomic benefits that this emerging technology may provide. Following a discussion on the causes of motion sickness in the context of self-driving cars, we present guidelines to steer the design and development of automated vehicle technologies. The aim is to limit or avoid the impact of motion sickness and ultimately promote the uptake of self-driving cars. Attention is also given to less well known consequences of motion sickness, in particular negative aftereffects such as postural instability, and detrimental effects on task performance and how this may impact the use and design of self-driving cars. We conclude that basic perceptual mechanisms need to be considered in the design process whereby self-driving cars cannot simply be thought of as living rooms, offices, or entertainment venues on wheels. PMID:26446454

  9. Parkinson disease and driving

    PubMed Central

    Classen, Sherrilene; Uc, Ergun Y.

    2012-01-01

    ABSTRACT The growing literature on driving in Parkinson disease (PD) has shown that driving is impaired in PD compared to healthy comparison drivers. PD is a complex neurodegenerative disorder leading to motor, cognitive, and visual impairments, all of which can affect fitness to drive. In this review, we examined studies of driving performance (on-road tests and simulators) in PD for outcome measures and their predictors. We searched through various databases and found 25 (of 99) primary studies, all published in English. Using the American Academy of Neurology criteria, a study class of evidence was assigned (I–IV, I indicating the highest level of evidence) and recommendations were made (Level A: predictive or not; B: probably predictive or not; C: possibly predictive or not; U: no recommendations). From available Class II and III studies, we identified various cognitive, visual, and motor measures that met different levels of evidence (usually Level B or C) with respect to predicting on-road and simulated driving performance. Class I studies reporting Level A recommendations for definitive predictors of driving performance in drivers with PD are needed by policy makers and clinicians to develop evidence-based guidelines. PMID:23150533

  10. A Behavioral Solution to the Drunk Driving Dilemma.

    ERIC Educational Resources Information Center

    Corey, Michael A.

    1988-01-01

    Discusses the problem of drunk driving primarily as a failure in the process of operant conditioning, with the inappropriate behavior of the drunk driver resulting from a profound ignorance of the potentially tragic consequences of his behavior. Concludes most effective way to understand consequences is to witness autopsies of drunk driving…

  11. Hydraulic drive system prevents backlash

    NASA Technical Reports Server (NTRS)

    Acord, J. D.

    1965-01-01

    Hydraulic drive system uses a second drive motor operating at reduced torque. This exerts a relative braking action which eliminates the normal gear train backlash that is intolerable when driving certain heavy loads.

  12. Family Influences and Unconscious Drives.

    ERIC Educational Resources Information Center

    English, Fanita

    2001-01-01

    Drives for survival, expression, and quiescence influence early human development and continue to influence career development throughout life. Turmoil may arise when a drive conflicts with others or is suppressed by other drives. (SK)

  13. 49 CFR 37.101 - Purchase or lease of vehicles by private entities not primarily engaged in the business of...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... not primarily engaged in the business of transporting people. 37.101 Section 37.101 Transportation... entities not primarily engaged in the business of transporting people. (a) Application. This section... business of transporting people, in which a solicitation for the vehicle is made after August 25, 1990....

  14. 49 CFR 37.101 - Purchase or lease of vehicles by private entities not primarily engaged in the business of...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... not primarily engaged in the business of transporting people. 37.101 Section 37.101 Transportation... entities not primarily engaged in the business of transporting people. (a) Application. This section... business of transporting people, in which a solicitation for the vehicle is made after August 25, 1990....

  15. 49 CFR 37.101 - Purchase or lease of vehicles by private entities not primarily engaged in the business of...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... not primarily engaged in the business of transporting people. 37.101 Section 37.101 Transportation... entities not primarily engaged in the business of transporting people. (a) Application. This section... business of transporting people, in which a solicitation for the vehicle is made after August 25, 1990....

  16. 49 CFR 37.101 - Purchase or lease of vehicles by private entities not primarily engaged in the business of...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... not primarily engaged in the business of transporting people. 37.101 Section 37.101 Transportation... entities not primarily engaged in the business of transporting people. (a) Application. This section... business of transporting people, in which a solicitation for the vehicle is made after August 25, 1990....

  17. 49 CFR 37.101 - Purchase or lease of vehicles by private entities not primarily engaged in the business of...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... not primarily engaged in the business of transporting people. 37.101 Section 37.101 Transportation... entities not primarily engaged in the business of transporting people. (a) Application. This section... business of transporting people, in which a solicitation for the vehicle is made after August 25, 1990....

  18. Passerine Exposure to Primarily PCDFs and PCDDs in the River Floodplains Near Midland, Michigan, USA

    PubMed Central

    Zwiernik, Matthew J.; Seston, Rita M.; Coefield, Sarah J.; Plautz, Stephanie C.; Tazelaar, Dustin L.; Shotwell, Melissa S.; Bradley, Patrick W.; Kay, Denise P.; Giesy, John P.

    2009-01-01

    House wren (Troglodytes aedon), tree swallow (Tachycineta bicolor), and eastern bluebird (Sialia sialis) tissues collected in study areas (SAs) downstream of Midland, Michigan (USA) contained concentrations of polychlorinated dibenzofurans (PCDFs) and polychlorinated dibenzo-p-dioxins (PCDDs) greater than in upstream reference areas (RAs) in the region. The sum of concentrations of PCDD/DFs (ΣPCDD/DFs) in eggs of house wrens and eastern bluebirds from SAs were 4- to 22-fold greater compared to those from RAs, whereas concentrations in tree swallow eggs were similar among areas. Mean concentrations of ΣPCDD/DFs and sum 2,3,7,8-tetrachlorodibenzo-p-dioxin equivalents (ΣTEQsWHO-Avian), based on 1998 WHO avian toxic equivalency factors, in house wren and eastern bluebird eggs ranged from 860 (430) to 1500 (910) ng/kg wet weight (ww) and 470 (150) to 1100 (510) ng/kg ww, respectively, at the most contaminated study areas along the Tittabawassee River, whereas mean concentrations in tree swallow eggs ranged from 280 (100) to 760 (280) ng/kg ww among all locations. Concentrations of ΣPCDD/DFs in nestlings of all studied species at SAs were 3- to 50-fold greater compared to RAs. Mean house wren, tree swallow, and eastern bluebird nestling concentrations of ΣPCDD/DFs and ΣTEQsWHO-Avian ranged from 350 (140) to 610 (300) ng/kg ww, 360 (240) to 1100 (860) ng/kg ww, and 330 (100) to 1200 (690) ng/kg ww, respectively, at SAs along the Tittabawassee River. Concentrations of ΣTEQsWHO-Avian were positively correlated with ΣPCDD/DF concentrations in both eggs and nestlings of all species studied. Profiles of relative concentrations of individual congeners were dominated by furan congeners (69–84%), primarily 2,3,7,8-tetrachlorodibenzofuran and 2,3,4,7,8-pentachlorodibenzofuran, for all species at SAs on the Tittabawassee and Saginaw rivers but were dominated by dioxin congeners at upstream RAs. Electronic supplementary material The online version of this article (doi:10

  19. Blast exposure in rats with body shielding is characterized primarily by diffuse axonal injury.

    PubMed

    Garman, Robert H; Jenkins, Larry W; Switzer, Robert C; Bauman, Richard A; Tong, Lawrence C; Swauger, Peter V; Parks, Steven A; Ritzel, David V; Dixon, C Edward; Clark, Robert S B; Bayir, Hülya; Kagan, Valerian; Jackson, Edwin K; Kochanek, Patrick M

    2011-06-01

    Blast-induced traumatic brain injury (TBI) is the signature insult in combat casualty care. Survival with neurological damage from otherwise lethal blast exposures has become possible with body armor use. We characterized the neuropathologic alterations produced by a single blast exposure in rats using a helium-driven shock tube to generate a nominal exposure of 35 pounds per square inch (PSI) (positive phase duration ∼ 4 msec). Using an IACUC-approved protocol, isoflurane-anesthetized rats were placed in a steel wedge (to shield the body) 7 feet inside the end of the tube. The left side faced the blast wave (with head-only exposure); the wedge apex focused a Mach stem onto the rat's head. The insult produced ∼ 25% mortality (due to impact apnea). Surviving and sham rats were perfusion-fixed at 24 h, 72 h, or 2 weeks post-blast. Neuropathologic evaluations were performed utilizing hematoxylin and eosin, amino cupric silver, and a variety of immunohistochemical stains for amyloid precursor protein (APP), glial fibrillary acidic protein (GFAP), ionized calcium-binding adapter molecule 1 (Iba1), ED1, and rat IgG. Multifocal axonal degeneration, as evidenced by staining with amino cupric silver, was present in all blast-exposed rats at all time points. Deep cerebellar and brainstem white matter tracts were most heavily stained with amino cupric silver, with the morphologic staining patterns suggesting a process of diffuse axonal injury. Silver-stained sections revealed mild multifocal neuronal death at 24 h and 72 h. GFAP, ED1, and Iba1 staining were not prominently increased, although small numbers of reactive microglia were seen within areas of neuronal death. Increased blood-brain barrier permeability (as measured by IgG staining) was seen at 24 h and primarily affected the contralateral cortex. Axonal injury was the most prominent feature during the initial 2 weeks following blast exposure, although degeneration of other neuronal processes was also present

  20. Exploring the metabolic potential of microbial communities in ultra-basic, reducing springs at The Cedars, CA, USA: Experimental evidence of microbial methanogenesis and heterotrophic acetogenesis

    NASA Astrophysics Data System (ADS)

    Kohl, Lukas; Cumming, Emily; Cox, Alison; Rietze, Amanda; Morrissey, Liam; Lang, Susan Q.; Richter, Andreas; Suzuki, Shino; Nealson, Kenneth H.; Morrill, Penny L.

    2016-04-01

    Present-day serpentinization generates groundwaters with conditions (pH > 11, Eh < -550 mV) favorable for the microbial and abiotic production of organic compounds from inorganic precursors. Elevated concentrations of methane, C2-C6 alkanes, acetate, and formate have been detected at these sites, but the microbial or abiotic origin of these compounds remains unclear. While geochemical data indicate that methane at most sites of present-day serpentinization is abiogenic, the stable carbon, hydrogen, and clumped isotope data as well as the hydrocarbon gas composition from The Cedars, CA, USA, are consistent with a microbial origin for methane. However, there is no direct evidence of methanogenesis at this site of serpentinization. We report on laboratory experiments in which the microbial communities in fluids and sediments from The Cedars were incubated with 13C labeled substrates. Increasing methane concentrations and the incorporation of 13C into methane in live experiments, but not in killed controls, demonstrated that methanogens converted methanol, formate, acetate (methyl group), and bicarbonate to methane. The apparent fractionation between methane and potential substrates (α13CCH4-CO2(g) = 1.059 to 1.105, α13CCH4-acetate = 1.042 to 1.119) indicated that methanogenesis was dominated by the carbonate reduction pathway. Increasing concentrations of volatile organic acid anions indicated microbial acetogenesis. α13CCO2(g)-acetate values (0.999 to 1.000), however, were inconsistent with autotrophic acetogenesis, thus suggesting that acetate was produced through fermentation. This is the first study to show direct evidence of microbial methanogenesis and acetogenesis by the native microbial community at a site of present-day serpentinization.

  1. Effects of Adaptation of In vitro Rumen Culture to Garlic Oil, Nitrate, and Saponin and Their Combinations on Methanogenesis, Fermentation, and Abundances and Diversity of Microbial Populations

    PubMed Central

    Patra, Amlan K.; Yu, Zhongtang

    2015-01-01

    This study investigated the effects of garlic oil (0.25 g/L), nitrate (5 mM), and quillaja saponin (0.6 g/L), alone and in binary or ternary combinations, on methanogenesis, rumen fermentation, and abundances of select microbial populations using in vitro rumen cultures. Potential adaptation to these compounds was also examined by repeated transfers of the cultures on alternate days until day 18. All treatments except saponin alone significantly decreased methanogenesis. Ternary combinations of garlic oil, nitrate, and saponin additively/synergistically suppressed methane production by 65% at day 2 and by 40% at day 18. Feed digestion was not adversely affected by any of the treatments at day 2, but was decreased by the combinations (binary and ternary) of garlic oil with the other inhibitors at days 10 and 18. Saponin, alone or in combinations, and garlic oil alone lowered ammonia concentration at day 2, while nitrate increased ammonia concentration at days 10 and 18. Total volatile fatty acid concentration was decreased by garlic oil alone or garlic oil-saponin combination. Molar proportions of acetate and propionate were affected to different extents by the different treatments. The abundances of methanogens were similar among treatments at day 2; however, garlic oil and its combination with saponin and/or nitrate at day 10 and all treatments except saponin at day 18 significantly decreased the abundances of methanogens. All the inhibitors, either alone or in combinations, did not adversely affect the abundances of total bacteria or Ruminococcus flavefaciens. However, at day 18 the abundances of Fibrobacter succinogenes and Ruminococcus albus were lowered in the presence of garlic oil and saponin, respectively. The results suggest that garlic oil-nitrate-saponin combination (at the doses used in this study) can effectively decreases methanogenesis in the rumen, but its efficacy may decrease while inhibition to feed digestion can increase over time. PMID:26733975

  2. Children's Theories and the Drive to Explain

    NASA Astrophysics Data System (ADS)

    Schwitzgebel, Eric

    Debate has been growing in developmental psychology over how much the cognitive development of children is like theory change in science. Useful debate on this topic requires a clear understanding of what it would be for a child to have a theory. I argue that existing accounts of theories within philosophy of science and developmental psychology either are less precise than is ideal for the task or cannot capture everyday theorizing of the sort that children, if they theorize, must do. I then propose an account of theories that ties theories and explanation very closely together, treating theories primarily as products of a drive to explain. I clarify some of the positions people have taken regarding the theory theory of development, and I conclude by proposing that psychologists interested in the ''theory theory'' look for patterns of affect and arousal in development that would accompany the existence of a drive to explain.

  3. Mental workload and driving

    PubMed Central

    Paxion, Julie; Galy, Edith; Berthelon, Catherine

    2014-01-01

    The aim of this review is to identify the most representative measures of subjective and objective mental workload in driving, and to understand how the subjective and objective levels of mental workload influence the performance as a function of situation complexity and driving experience, i.e., to verify whether the increase of situation complexity and the lack of experience increase the subjective and physiological levels of mental workload and lead to driving performance impairments. This review will be useful to both researchers designing an experimental study of mental workload and to designers of drivers’ training content. In the first part, we will broach the theoretical approach with two factors of mental workload and performance, i.e., situation complexity and driving experience. Indeed, a low complex situation (e.g., highways), or conversely a high complex situation (e.g., town) can provoke an overload. Additionally, performing the driving tasks implies producing a high effort for novice drivers who have not totally automated the driving activity. In the second part, we will focus on subjective measures of mental workload. A comparison of questionnaires usually used in driving will allow identifying the most appropriate ones as a function of different criteria. Moreover, we will review the empirical studies to verify if the subjective level of mental workload is high in simple and very complex situations, especially for novice drivers compared to the experienced ones. In the third part, we will focus on physiological measures. A comparison of physiological indicators will be realized in order to identify the most correlated to mental workload. An empirical review will also take the effect of situation complexity and experience on these physiological indicators into consideration. Finally, a more nuanced comparison between subjective and physiological measures will be established from the impact on situation complexity and experience. PMID:25520678

  4. Direct Drive for Low Power Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.

    2005-01-01

    Due to recent studies, NASA has initiated the development of a low power Hall thruster for discovery class missions. The potential advantages of a low power Hall thruster is primarily due to its high efficiency operation at low power and its lower complexity compared to ion engines. Direct drive is another method of reducing the complexity of a Hall thruster system while improving its efficiency. The technical challenges associated with this technology are reported. Additionally, the benefits of this technology are discussed based on parametric studies and mission analysis.

  5. Fundamental limitations on 'warp drive' spacetimes

    NASA Astrophysics Data System (ADS)

    Lobo, Francisco S. N.; Visser, Matt

    2004-12-01

    'Warp drive' spacetimes are useful as 'gedanken-experiments' that force us to confront the foundations of general relativity, and among other things, to precisely formulate the notion of 'superluminal' communication. After carefully formulating the Alcubierre and Natário warp drive spacetimes, and verifying their non-perturbative violation of the classical energy conditions, we consider a more modest question and apply linearized gravity to the weak-field warp drive, testing the energy conditions to first and second orders of the warp-bubble velocity, v. Since we take the warp-bubble velocity to be non-relativistic, v Lt c, we are not primarily interested in the 'superluminal' features of the warp drive. Instead we focus on a secondary feature of the warp drive that has not previously been remarked upon—the warp drive (if it could be built) would be an example of a 'reaction-less drive'. For both the Alcubierre and Natário warp drives we find that the occurrence of significant energy condition violations is not just a high-speed effect, but that the violations persist even at arbitrarily low speeds. A particularly interesting feature of this construction is that it is now meaningful to think of placing a finite mass spaceship at the centre of the warp bubble, and then see how the energy in the warp field compares with the mass energy of the spaceship. There is no hope of doing this in Alcubierre's original version of the warp field, since by definition the point at the centre of the warp bubble moves on a geodesic and is 'massless'. That is, in Alcubierre's original formalism and in the Natário formalism the spaceship is always treated as a test particle, while in the linearized theory we can treat the spaceship as a finite mass object. For both the Alcubierre and Natário warp drives we find that even at low speeds the net (negative) energy stored in the warp fields must be a significant fraction of the mass of the spaceship.

  6. Driving Anger and Driving Behavior in Adults with ADHD

    ERIC Educational Resources Information Center

    Richards, Tracy L.; Deffenbacher, Jerry L.; Rosen, Lee A.; Barkley, Russell A.; Rodricks, Trisha

    2006-01-01

    Objective: This study assesses whether anger in the context of driving is associated with the negative driving outcomes experienced by individuals with ADHD. Method: ADHD adults (n = 56) complete measures of driving anger, driving anger expression, angry thoughts behind the wheel, and aggressive, risky, and crash-related behavior. Results are…

  7. Driving anger in Malaysia.

    PubMed

    Sullman, Mark J M; Stephens, Amanda N; Yong, Michelle

    2014-10-01

    The present study examined the types of situations that cause Malaysian drivers to become angry. The 33-item version of the driver anger scale (Deffenbacher et al., 1994) was used to investigate driver anger amongst a sample of 339 drivers. Confirmatory factor analysis showed that the fit of the original six-factor model (discourtesy, traffic obstructions, hostile gestures, slow driving, illegal driving and police presence), after removing one item and allowing three error pairs to covary, was satisfactory. Female drivers reported more anger, than males, caused by traffic obstruction and hostile gestures. Age was also negatively related to five (discourtesy, traffic obstructions, hostile gestures, slow driving and police presence) of the six factors and also to the total DAS score. Furthermore, although they were not directly related to crash involvement, several of the six forms of driving anger were significantly related to the crash-related conditions of: near misses, loss of concentration, having lost control of a vehicle and being ticketed. Overall the pattern of findings made in the present research were broadly similar to those from Western countries, indicating that the DAS is a valid measure of driving anger even among non-European based cultures. PMID:24863369

  8. [Drug use and driving].

    PubMed

    Lemaire-Hurtel, Anne-Sophie; Goullé, Jean-Pierre; Alvarez, Jean-Claude; Mura, Patrick; Verstraete, Alain G

    2015-10-01

    Some drugs are known to impair driving because they can change the vision or hearing, and/or disrupt the intellectual or motor abilities: impaired vigilance, sedation, disinhibition effect, the coordination of movement disorders and the balance. The doctor during prescribing and the pharmacist during deliverance of drug treatment should inform their patients of the potential risks of drugs on driving or operating machinery. The driver has direct responsibility, who hired him and him alone, to follow the medical advice received. The pictograms on the outer packaging of medicinal products intended to classify substances according to their risk driving: The driver can whether to observe simple precautions (level one "be prudent"), or follow the advice of a health professional (level two "be very careful"), or if it is totally not drive (level three "danger caution: do not drive"). This classification only evaluates the intrinsic danger of drugs but not the individual variability. Medicines should be taken into account also the conditions for which the medication is prescribed. It is important to inform the patient on several points. PMID:25956300

  9. Empathic concern drives costly altruism

    PubMed Central

    FeldmanHall, Oriel; Dalgleish, Tim; Evans, Davy; Mobbs, Dean

    2015-01-01

    Why do we self-sacrifice to help others in distress? Two competing theories have emerged, one suggesting that prosocial behavior is primarily motivated by feelings of empathic other-oriented concern, the other that we help mainly because we are egoistically focused on reducing our own discomfort. Here we explore the relationship between costly altruism and these two sub-processes of empathy, specifically drawing on the caregiving model to test the theory that trait empathic concern (e.g. general tendency to have sympathy for another) and trait personal distress (e.g. predisposition to experiencing aversive arousal states) may differentially drive altruistic behavior. We find that trait empathic concern – and not trait personal distress – motivates costly altruism, and this relationship is supported by activity in the ventral tegmental area, caudate and subgenual anterior cingulate, key regions for promoting social attachment and caregiving. Together, this data helps identify the behavioral and neural mechanisms motivating costly altruism, while demonstrating that individual differences in empathic concern-related brain responses can predict real prosocial choice. PMID:25462694

  10. Ceramic vane drive joint

    DOEpatents

    Smale, Charles H.

    1981-01-01

    A variable geometry gas turbine has an array of ceramic composition vanes positioned by an actuating ring coupled through a plurality of circumferentially spaced turbine vane levers to the outer end of a metallic vane drive shaft at each of the ceramic vanes. Each of the ceramic vanes has an end slot of bow tie configuration including flared end segments and a center slot therebetween. Each of the vane drive shafts has a cross head with ends thereof spaced with respect to the sides of the end slot to define clearance for free expansion of the cross head with respect to the vane and the cross head being configured to uniformly distribute drive loads across bearing surfaces of the vane slot.

  11. U.S. DRIVE

    SciTech Connect

    2012-03-16

    U.S. DRIVE, which stands for United States Driving Research and Innovation for Vehicle efficiency and Energy sustainability, is an expanded government-industry partnership among the U.S. Department of Energy; USCAR, representing Chrysler Group LLC, Ford Motor Company and General Motors; Tesla Motors; five energy companies – BP America, Chevron Corporation, ConocoPhillips, ExxonMobil Corporation, and Shell Oil Products US; two utilities – Southern California Edison and Michigan-based DTE Energy; and the Electric Power Research Institute (EPRI). The U.S. DRIVE mission is to accelerate the development of pre-competitive and innovative technologies to enable a full range of affordable and clean advanced light-duty vehicles, as well as related energy infrastructure.

  12. LCLS Injector Drive Laser

    SciTech Connect

    Dowell, D.H.; Castro, J.; Emma, P.; Frisch, J.; Gilevich, A.; Hays, G.; Hering, P.; Limborg-Deprey, C.; Loos, H.; Miahnahri, A.; White, W.; /SLAC

    2007-11-02

    Requirements for the LCLS injector drive laser present significant challenges to the design of the system. While progress has been demonstrated in spatial shape, temporal shape, UV generation and rep-rate, a laser that meets all of the LCLS specifications simultaneously has yet to be demonstrated. These challenges are compounded by the stability and reliability requirements. The drive laser and transport system has been installed and tested. We will report on the current operational state of the laser and plans for future improvements.

  13. Optotech 5984 Drive Overview

    NASA Astrophysics Data System (ADS)

    Lee, Tzuo-Chang; Chen, Di

    1987-01-01

    We present in this paper an overview of Optotech's 5984 Optical Disk Drive. Key features such as the modulation code, the disk format, defect mapping scheme and the optical head and servo subsystem will be singled out for discussion. Description of Optotech's 5984 disk drive The Optotech 5984 optical disk drive is a write-once-read-mostly (WORM) rotating optical memory with 200 Megabyte capacity on each side of the disk. It has a 5 1/4 inch form factor that will fit into any personal computer full-height slot. The drive specification highlights are given in Table 1. A perspective view of the drive mechanical assembly is shown in Figure 1. The spindle that rotates the disk has a runout of less than 10 um. The rotational speed at 1200 revolutions per minute (rpm) is held to an accuracy of 10-3. The total angular tolerance from perfect perpendicular alignment between the rotating disk and the incident optical beam axis is held to less than 17 milliradians. The coarse seek is accomplished through a stepping motor driving the optical head with 1.3 milliseconds per step or 32 tracks per step. The analog channels including read/write, the phase lock loop and the servo loops for focus and track control are contained on one surface mount pc board while the digital circuitry that interfaces with the drive and the controller is on a separate pc board. A microprocessor 8039 is used to control the handshake and the sequence of R/W commands. A separate power board is used to provide power to the spindle and the stepping motors. In the following we will discuss some of the salient features in the drive and leave the details to three accompanying Optotech papers. These salient features are derived from a design that is driven by three major considerations. One is precise control of the one micron diameter laser spot to any desired location on the disk. The second consideration is effective management of media defects. Given the state of the art of the Te-based disk technology with

  14. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

    Accurate and controlled drive for the control rod is from an electric motor. A hydraulic arrangement is provided to balance a piston against which a control rod is urged by the application of fluid pressure. The electric motor drive of the control rod for normal operation is made through the aforementioned piston. In the event scramming is required, the fluid pressure urging the control rod against the piston is relieved and an opposite fluid pressure is applied. The lack of mechanical connection between the electric motor and control rod facilitates the scramming operation.

  15. Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate.

    PubMed

    Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge M; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2016-01-01

    CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in carbon dioxide capture and storage (CDCS) facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form; 0∼90 mM) with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs. PMID:27047478

  16. Formate-Dependent Microbial Conversion of CO2 and the Dominant Pathways of Methanogenesis in Production Water of High-temperature Oil Reservoirs Amended with Bicarbonate

    PubMed Central

    Yang, Guang-Chao; Zhou, Lei; Mbadinga, Serge M.; Liu, Jin-Feng; Yang, Shi-Zhong; Gu, Ji-Dong; Mu, Bo-Zhong

    2016-01-01

    CO2 sequestration in deep-subsurface formations including oil reservoirs is a potential measure to reduce the CO2 concentration in the atmosphere. However, the fate of the CO2 and the ecological influences in carbon dioxide capture and storage (CDCS) facilities is not understood clearly. In the current study, the fate of CO2 (in bicarbonate form; 0∼90 mM) with 10 mM of formate as electron donor and carbon source was investigated with high-temperature production water from oilfield in China. The isotope data showed that bicarbonate could be reduced to methane by methanogens and major pathway of methanogenesis could be syntrophic formate oxidation coupled with CO2 reduction and formate methanogenesis under the anaerobic conditions. The bicarbonate addition induced the shift of microbial community. Addition of bicarbonate and formate was associated with a decrease of Methanosarcinales, but promotion of Methanobacteriales in all treatments. Thermodesulfovibrio was the major group in all the samples and Thermacetogenium dominated in the high bicarbonate treatments. The results indicated that CO2 from CDCS could be transformed to methane and the possibility of microbial CO2 conversion for enhanced microbial energy recovery in oil reservoirs. PMID:27047478

  17. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

    Acting on information from students who reported seeing a classmate looking at inappropriate material on a school computer, school officials used forensics software to plunge the depths of the PC's hard drive, searching for evidence of improper activity. Images were found in a deleted Internet Explorer cache as well as deleted file space.…

  18. DrivePy

    Energy Science and Technology Software Center (ESTSC)

    2014-08-30

    DrivePy is physics-based drivetrain model that sizes drivetrain components based on aerodynamic and operational loads for use in a systems engineering model. It also calculates costs based on empirical data collected by NREL's National Wind Technology Center.

  19. No Pass, No Drive?

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2001-01-01

    Discusses basis for Kentucky appellate court decision that state's no-pass, no-drive statute did not violate due-process and equal-protection clauses of the Kentucky and federal constitutions, but did violate the federal Family Education Rights and Privacy Act, but nevertheless did not invalidate the statute. Explains why the decision is…

  20. Teachers with Drive

    ERIC Educational Resources Information Center

    Coggins, Celine; Diffenbaugh, P. K.

    2013-01-01

    For students in U.S. classrooms today, the odds of being assigned to an inexperienced teacher are higher than they have ever been because so many teachers, some in the top 20 percent of effectiveness are leaving the classroom in their first five years. Coggins and Diffenbaugh turn to Daniel Pink's work on drive to determine how to motivate…

  1. [Epilepsy and driving].

    PubMed

    Adam, Claude

    2015-10-01

    Epilepsy contributes little to road traffic accidents (0.25% of accidents) compared, for instance, to alcohol abuse (at least 30 times higher). Current factors, such as age and sex, or other chronic medical conditions also increase the risk of road traffic accidents but do not carry driving restrictions. So, the European Commission fairly established rules permitting individuals having experienced one or more epileptic seizures to drive if their road accident risk is low. Road accident risk related to epileptic seizures in various clinical situations is evaluated by the driving license commission, mainly with the aid of criteria based on seizure-free periods. A person who has had an epileptic seizure should notify the authorities. He should be advised by treating physician not to drive before. In case of an authorisation, any new relevant event should be notified to the authorities in the course of legal follow-up. Improvements of the current regulations by European data registries are under way. PMID:26482490

  2. COMMENT: No warp drive

    NASA Astrophysics Data System (ADS)

    Coule, D. H.

    1998-08-01

    The warp drive spacetime of Alcubierre is impossible to set up without first being able to distribute matter at tachyonic speed, put roughly, you need one to make one! However, over small distances, where the energy conditions possibly can be violated, one can envision opening the light-cones to increase the apparent speed of light.

  3. Drive-Through Training

    ERIC Educational Resources Information Center

    Carter, Margie

    2010-01-01

    In this article, the author discusses how the early childhood field's approach to staff training reflects the drive-through, fast-food culture. Year after year directors send their teachers to workshops to get some quick refresher techniques. The author suggests that rather than focusing professional development on topics, focus on observing…

  4. Driving skills after whiplash.

    PubMed

    Gimse, R; Bjørgen, I A; Straume, A

    1997-09-01

    Previous studies have shown that some persons with longlasting problems after whiplash have changed eye movements. These changes have been related to disturbance of the posture control system. The question raised in the present study is whether such disturbances can influence daily life functions connected with balance, position and external movements, such as car driving. A group of 23 persons with disturbed eye movements due to whiplash injury, was tested in a driving simulator, together with a closely matched control group. The results revealed significant differences between the two groups with respect to response times to the traffic signs presented, identification of type of sign, as well as steering precision while the subjects' attention was directed to the process of identifying the signs. Alternative explanations such as driving experience, pain, medication or malingering are at least partly controlled for, but cannot completely be ruled out. A distorted posture control system leading to disturbance of eye movements seems to be the most likely primary causative factor, but these disturbances are most certainly complexly determined. Reduced attention capacity is considered to be a mediating secondary factor. Registration of eye movements may be a useful diagnostic tool to evaluate driving skill after whiplash. PMID:9309948

  5. Driving While Intoxicated.

    ERIC Educational Resources Information Center

    Brick, John

    Alcohol intoxication increases the risk of highway accidents, the relative risk of crash probability increasing as a function of blood alcohol content (BAC). Because alcohol use is more prevalent than use of other drugs, more is known about the relationship between alcohol use and driving. Most states presume a BAC of .10% to be evidence of drunk…

  6. Identifying periods of drowsy driving using EEG.

    PubMed

    Brown, Timothy; Johnson, Robin; Milavetz, Gary

    2013-01-01

    Drowsy driving is a significant contributor to death and injury crashes on our nation's highways. Predictive neurophysiologic/physiologic solutions to reduce these incidences have been proposed and developed. EEG based metrics were found to be promising in initial studies, but remain controversial in their efficacy, primarily due to failures to develop replication studies within the simulation settings used for development, and real-world validation. This analysis sought to address these short comings by assessing the utility of the B-Alert algorithms, in a replication study of driving and drowsiness. Data were collected on the National Advanced Driving Simulator from 72 volunteer drivers exposed to three types of roadways at three times of day representing different levels of drowsiness. EEG metrics, collected using the B-Alert X10 Wireless Headset were evaluated to determine their utility in future predictive studies. The replication of the B-Alert algorithms was a secondary focus for this analysis, resulting in highly variable start times within each time of day segment, leading to EEG data being confounded by the diurnal variations that occur in the basal EEG signal. Regardless of this limitation, the analysis revealed promising outcomes. The EEG based algorithms for sleep onset, drowsiness, as well as fatigue related power spectral bandwidths (i.e. lateral central, and parietal alpha) varied with time of day of the drives. Interestingly, EEG metrics of cognitive workload were also sensative to the terrain of the drives. The replicaiton of the B-Alert algorithms were a secondary focuse in the study design, Taken together, these data indicate great potential of carefully designed studies to utilize neurophysiologic metrics to identify time of day and task and road conditions that may be at greatest risk during fatigued/drowsy periods. PMID:24406950

  7. Speed sensorless hybrid vector controlled induction motor drive

    SciTech Connect

    Bose, B.K.; Simoes, M.G.; Crecelius, D.R.; Rajashekara, K.; Martin, R.

    1995-12-31

    The paper describes a speed and flux sensorless vector-controlled induction motor drive primarily aimed for electric vehicle type applications. The stator flux oriented drive starts at zero speed in indirect vector control mode, transitions to direct vector control mode as the speed develops, and then transitions back to indirect vector control at zero speed. The vector control uses stator flux orientation in both indirect and direct vector control modes with the stator resistance variation compensated by measurement of stator temperature. The problem of integration at low stator frequency is solved by cascaded low pass filters with programmable time constants. The control strategy of the four-quadrant drive has been analyzed, validated by simulation study, and finally evaluated by experimental study on a laboratory 5 hp drive system.

  8. Autonomous driving in urban environments: approaches, lessons and challenges.

    PubMed

    Campbell, Mark; Egerstedt, Magnus; How, Jonathan P; Murray, Richard M

    2010-10-13

    The development of autonomous vehicles for urban driving has seen rapid progress in the past 30 years. This paper provides a summary of the current state of the art in autonomous driving in urban environments, based primarily on the experiences of the authors in the 2007 DARPA Urban Challenge (DUC). The paper briefly summarizes the approaches that different teams used in the DUC, with the goal of describing some of the challenges that the teams faced in driving in urban environments. The paper also highlights the long-term research challenges that must be overcome in order to enable autonomous driving and points to opportunities for new technologies to be applied in improving vehicle safety, exploiting intelligent road infrastructure and enabling robotic vehicles operating in human environments. PMID:20819826

  9. [Driving ability with multiple sclerosis].

    PubMed

    Küst, J; Dettmers, C

    2014-07-01

    Driving is an important issue for young patients, especially for those whose walking capacity is impaired. Driving might support the patient's social and vocational participation. The question as to whether a patient with multiple sclerosis (MS) is restricted in the ability to drive a car depends on neurological and neuropsychological deficits, self-awareness, insight into deficits and ability to compensate for loss of function. Because of the enormous variability of symptoms in MS the question is highly individualized. A practical driving test under supervision of a driving instructor (possibly accompanied by a neuropsychologist) might be helpful in providing both patient and relatives adequate feedback on driving abilities. PMID:24906536

  10. Drive-by-Downloads

    SciTech Connect

    Narvaez, Julia; Endicott-Popovsky, Barbara E.; Seifert, Christian; Aval, Chiraag U.; Frincke, Deborah A.

    2010-02-01

    Abstract: Drive-by-downloads are malware that push, and then execute, malicious code on a client system without the user's consent. The purpose of this paper is to introduce a discussion of the usefulness of antivirus software for detecting the installation of such malware, providing groundwork for future studies. Client honeypots collected drive-by malware which was then evaluated using common antivirus products. Initial analysis showed that most of such antivirus products identified less than 70% of these highly polymorphic malware programs. Also, it was observed that the antivirus products tested, even when successfully detecting this malware, often failed to classify it, leading to the conclusion that further work could involve not only developing new behavioral detection technologies, but also empirical studies that improve general understanding of these threats. Toward that end, one example of malicious code was analyzed behaviorally to provide insight into next steps for the future direction of this research.

  11. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1990-01-01

    Developing magnetostrictive direct drive research motors to power robot joints is discussed. These type motors are expected to produce extraordinary torque density, to be able to perform microradian incremental steps and to be self-braking and safe with the power off. Several types of motor designs have been attempted using magnetostrictive materials. One of the candidate approaches (the magnetostrictive roller drive) is described. The method in which the design will function is described as is the reason why this approach is inherently superior to the other approaches. Following this, the design will be modelled and its expected performance predicted. This particular candidate design is currently undergoing detailed engineering with prototype construction and testing scheduled for mid 1991.

  12. Variable speed drive

    NASA Technical Reports Server (NTRS)

    Obler, H. D. (Inventor)

    1983-01-01

    A variable speed drive wherein a first embodiment is comprised of a pivotally mounted prime mover coupled to a rotary fluid output device, such as a fan or pump, through a variable and fixed pulley drive arrangement is described. The pivotal position of the prime mover and accordingly the pitch diameter of variable pulley means is controlled in accordance with fluid motor means coupled to the prime mover. This is actuated in response to a fluid feedback control signal derived from a sensed output of the rotary fluid output device. The pivotal motion of the prime mover imparts an arcuate motion to the variable pulley means which effects a speed variation of the rotary fluid output device in accordance with the variation of the pitch diameter ratio of opposing variable and fixed pulley means.

  13. Sex chromosome drive.

    PubMed

    Helleu, Quentin; Gérard, Pierre R; Montchamp-Moreau, Catherine

    2015-02-01

    Sex chromosome drivers are selfish elements that subvert Mendel's first law of segregation and therefore are overrepresented among the products of meiosis. The sex-biased progeny produced then fuels an extended genetic conflict between the driver and the rest of the genome. Many examples of sex chromosome drive are known, but the occurrence of this phenomenon is probably largely underestimated because of the difficulty to detect it. Remarkably, nearly all sex chromosome drivers are found in two clades, Rodentia and Diptera. Although very little is known about the molecular and cellular mechanisms of drive, epigenetic processes such as chromatin regulation could be involved in many instances. Yet, its evolutionary consequences are far-reaching, from the evolution of mating systems and sex determination to the emergence of new species. PMID:25524548

  14. Forces Driving Chaperone Action.

    PubMed

    Koldewey, Philipp; Stull, Frederick; Horowitz, Scott; Martin, Raoul; Bardwell, James C A

    2016-07-14

    It is still unclear what molecular forces drive chaperone-mediated protein folding. Here, we obtain a detailed mechanistic understanding of the forces that dictate the four key steps of chaperone-client interaction: initial binding, complex stabilization, folding, and release. Contrary to the common belief that chaperones recognize unfolding intermediates by their hydrophobic nature, we discover that the model chaperone Spy uses long-range electrostatic interactions to rapidly bind to its unfolded client protein Im7. Short-range hydrophobic interactions follow, which serve to stabilize the complex. Hydrophobic collapse of the client protein then drives its folding. By burying hydrophobic residues in its core, the client's affinity to Spy decreases, which causes client release. By allowing the client to fold itself, Spy circumvents the need for client-specific folding instructions. This mechanism might help explain how chaperones can facilitate the folding of various unrelated proteins. PMID:27293188

  15. Advanced Motor Drives Studies

    NASA Technical Reports Server (NTRS)

    Ehsani, M.; Tchamdjou, A.

    1997-01-01

    This report presents an evaluation of advanced motor drive systems as a replacement for the hydrazine fueled APU units. The replacement technology must meet several requirements which are particular to the space applications and the Orbiter in general. Some of these requirements are high efficiency, small size, high power density. In the first part of the study several motors are compared, based on their characteristics and in light of the Orbiter requirements. The best candidate, the brushless DC is chosen because of its particularly good performance with regards to efficiency. Several power electronics drive technologies including the conventional three-phase hard switched and several soft-switched inverters are then presented. In the last part of the study, a soft-switched inverter is analyzed and compared to its conventional hard-switched counterpart. Optimal efficiency is a basic requirement for space applications and the soft-switched technology represents an unavoidable trend for the future.

  16. Gear Drive Testing

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Philadelphia Gear Corporation used two COSMIC computer programs; one dealing with shrink fit analysis and the other with rotor dynamics problems in computerized design and test work. The programs were used to verify existing in-house programs to insure design accuracy by checking its company-developed computer methods against procedures developed by other organizations. Its specialty is in custom units for unique applications, such as Coast Guard ice breaking ships, steel mill drives, coal crusher, sewage treatment equipment and electricity.

  17. Driving on the Descartes

    NASA Technical Reports Server (NTRS)

    1972-01-01

    Astronaut John W. Young, Apollo 16 mission commander, drives the 'Rover', Lunar Roving Vehicle (LRV) to its final parking place near the end of the third extravehicular activity (EVA-3) at the Descartes landing site. Astronaut Charles M. Duke Jr., Lunar Module pilot, took this photograph looking southward. The flank of Stone Mountain can be seen on the horizon at left. The shadow of the Lunar Module 'Orion' is visible in the foreground.

  18. Variable reluctance drive system

    SciTech Connect

    Lipo, T.A.; Liang, F.

    1995-10-17

    A variable reluctance drive system including a motor and corresponding converter for improved current commutation is described. The motor incorporates a salient pole rotor and a salient pole stator having one or more full pitch windings which operate by mutual inductance to transfer the current from the active short pitch winding following phase alignment. This increases output torque and/or speed and permits a number of simple and economical converter circuits. 17 figs.

  19. [Automobile driving capacity in dementia].

    PubMed

    Seeger, Rolf

    2015-04-01

    Dementia influences at an early stage the driving aptitude of motor vehicle steering persons. Every year in Switzerland, around 16'000 driving permit holders suffer newly from dementia; therefore the driving aptitude is questioned, especially because of possibly limited executive functions. Individuals with early-stage dementia often may show a dangerous driving stile. However, a mild dementia does not a priori exclude the driving aptitude, and less than half of these drivers can continue driving for another 1 - 3 years. In contrast, there is no further driving aptitude in presence of moderate dementia. In the assessment of driving aptitude, the underlying cause of dementia is always taken into account. Cognitive short tests such as the Mini-Mental Status Exam, Clock Drawing Test and Trail-Making Test are not suitable to make reliable statements about the aptitude to drive, but these tests are very important for the initial diagnosis of dementia in primary care practice and can lead the way for further examination concerning driving aptitude. The legally prescribed regular check-up for motorists aged over 70 years in Switzerland provides an ideal opportunity for early detection of incipient dementia. The practical procedure for the assessment of aptitude to drive in the primary care practice is presented. The physician-guided on-road driving test represents a meaningful, practical and relatively cost-effective tool for the evaluation of driving aptitude in cases of doubt. PMID:25791047

  20. Who's Driving Home?: Assessing Adolescent Drinking and Driving.

    ERIC Educational Resources Information Center

    Swisher, John D.; Bibeau, Daniel

    1987-01-01

    Data from 13,998 students revealed that high percentages of students drank often and that many of these students reported being drunk often. While most students indicated they would prefer not to drive home after drinking, approximately one-third of driving age students indicated they would drive under the influence of alcohol or would ride with…

  1. Methanogenesis produces strong 13C-enrichment in stromatolites of Lagoa Salgada, Brazil: A modern analogue for Palaeo-/Neoproterozoic stromatolites?

    NASA Astrophysics Data System (ADS)

    Meister, Patrick; Birgel, Daniel; Lundberg, Rebecca; Horat, Thomas; Bontognali, Tomaso; Bahniuk Rumbelsperger, Anelize; Rezende, Carlos; Vásconcelos, Crisógono; McKenzie, Judith A.

    2015-04-01

    Holocene stromatolites characterized by unusually positive inorganic carbon isotope values (δ13C up to +16 ‰ relative to the Vienna Peedee Belemnite Standard; VPDB) are present in Lagoa Salgada, a seasonally brackish to hypersaline lagoon near Rio de Janeiro (Brazil). Such positive values cannot be explained by phototrophic fixation of CO2 alone. Instead, strong carbon isotope fractionation is commonly observed during methanogenesis, where isotopically light C is preferentially incorporated into methane and the residual inorganic carbon is 13C-enriched. We suggest that methanogenesis was the dominating process of organic carbon mineralization during the growth of the stromatolites. Indeed, the presence of dissolved methane in porewater (up to 5 mM) and the archaeal membrane lipid archaeol showing relatively high δ13C values (-15 to 0 ‰ VPDB) indicates that methanogenic archaea are present and active in the modern lagoon sediment. Moreover, 13C-depleted hopanoids diplopterol and 3-methylated bishomohopanoic acid (both -40‰ VPDB) are preserved in lagoon sediments and are most likely derived from aerobic methanotrophic bacteria thriving in the methane-enriched water column. Loss of isotopically light methane through the water column to the atmosphere would explain the residual 13C-enriched pool of dissolved inorganic carbon from where the carbonate constituting the stromatolites precipitated. The predominance of methanogenic archaea in the lagoon is most likely a result of sulphate limitation suppressing the activity of sulphate-reducing bacteria under brackish conditions in a seasonally humid tropical and arid environment. Also in the modern sediments, sulphate reduction activity is very low. Under dominating methanogenic conditions and in absence of an efficient carbonate-inducing metabolic process, we propose that stromatolite formation in Lagoa Salgada was abiotically induced while the 13C-enriched organic and inorganic carbon pools are due to

  2. In-office evaluation of medical fitness to drive

    PubMed Central

    Molnar, Frank J.; Byszewski, Anna M.; Marshall, Shawn C.; Man-Son-Hing, Malcolm

    2005-01-01

    OBJECTIVE To provide background for physicians’ in-office assessment of medical fitness to drive, including legal risks and responsibilities. To review opinion-based approaches and current attempts to promote evidence-based strategies for this assessment. QUALITY OF EVIDENCE MEDLINE, EMBASE, CINAHL, PsycINFO, Ageline, and Sociofile were searched from 1966 on for articles on health-related and medical aspects of fitness to drive. More than 1500 papers were reviewed to find practical approaches to, or guidelines for, assessing medical fitness to drive in primary care. Only level III evidence was found. No evidence-based approaches were found. MAIN MESSAGE Three practical methods of assessment are discussed: the American Medical Association guidelines, SAFE DRIVE, and CanDRIVE. CONCLUSION There is no evidence-based information to help physicians make decisions regarding medical fitness to drive. Current approaches are primarily opinion-based and are of unknown predictive value. Research initiatives, such as the CanDRIVE program of the Canadian Institutes of Health Research, can provide empiric data that would allow us to move from opinion to evidence. PMID:15794022

  3. Do we really need to use our smartphones while driving?

    PubMed

    Musicant, Oren; Lotan, Tsippy; Albert, Gila

    2015-12-01

    Smartphone usage while driving, a prominent type of driver distraction, has become a major concern in the area of road safety. Answers to an internet survey by 757 Israeli drivers who own smartphones were analyzed with focus on two main purposes: (1) to gain insights regarding patterns of smartphone usage while driving and its motivation, (2) to probe drivers' views on the perceived risk and the need to use smartphones while driving, as well as their willingness to use blocking apps that limit such usages. Phone calls and texting were found to be the most common usages while driving, hence, both were chosen to be further analyzed. 73% (N=551) of the respondents make phone calls while driving and almost half of them may be considered frequent callers as they admit to do it intensively while driving. As for texting, 35% of the respondents (N=256) text while driving and a quarter of them do so frequently. While phone calls were perceived to compromise safety by 34% of the users, texting was perceived to compromise safety by 84% of the users. However, we found that drivers place limitations on themselves as more than 70% avoid texting when they think they need to devote attention to driving. A logistic regression model indicates that perceived need and perceived safety are significant factors associated with being a frequent smartphone phone calls user, but only perceived need significantly predicts being a frequent texting user. Approximately half of all the respondents are willing to try an app which blocks smartphone usage while driving. The willingness to use such technology was found to be related primarily to perceived need. Less significant factors are work-related usage and perceived safety. Frequency of usage was not found to affect this willingness, indicating that it should not be a factor in designing and implementing interventions to limit smartphone usage while driving. PMID:26364139

  4. 49 CFR 178.337 - Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178.337 Section 178.337 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS...

  5. 49 CFR 178.337 - Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178.337 Section 178.337 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS...

  6. 49 CFR 178.337 - Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178.337 Section 178.337 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS...

  7. 49 CFR 178.337 - Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178.337 Section 178.337 Transportation Other Regulations Relating to Transportation (Continued) PIPELINE AND HAZARDOUS MATERIALS...

  8. 49 CFR 178.337 - Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178.337 Section 178.337 Transportation Other Regulations Relating to Transportation PIPELINE AND HAZARDOUS MATERIALS SAFETY...

  9. The therapeutic efficacy of the oncolytic virus Delta24-RGD in a murine glioma model depends primarily on antitumor immunity

    PubMed Central

    Kleijn, Anne; Kloezeman, Jenneke; Treffers-Westerlaken, Elike; Fulci, Giulia; Leenstra, Sieger; Dirven, Clemens; Debets, Reno; Lamfers, Martine

    2014-01-01

    Oncolytic viruses selectively lyse tumor cells, making these agents a promising treatment modality for glioma. Accumulating data suggest that the immune system plays an important role in the anti-glioma activity of oncolytic viruses. In an immune competent glioma model, the therapeutic effect of the oncolytic adenovirus Delta24-RGD was found to depend primarily on antitumor immune responses. PMID:25941622

  10. Drive alignment pays maintenance dividends

    SciTech Connect

    Fedder, R.

    2008-12-15

    Proper alignment of the motor and gear drive on conveying and processing equipment will result in longer bearing and coupling life, along with lower maintenance costs. Selecting an alignment free drive package instead of a traditional foot mounted drive and motor is a major advancement toward these goals. 4 photos.

  11. Drive Diagnostic Filter Wheel Control

    Energy Science and Technology Software Center (ESTSC)

    2007-07-17

    DrD Filter Wheel Control is National Instrument's Labview software that drives a Drive Diagnostic filter wheel. The software can drive the filter wheel between each end limit, detect the positive and negative limit and each home position and post the stepper motot values to an Excel spreadsheet. The software can also be used to cycle the assembly between the end limits.

  12. Exploring the Metabolic Potential of Microbial Communities in Ultra-basic Reducing Spring at The Cedars, CA: Evidence of Microbial Methanogenesis and Heterotrophic Acetogenesis

    NASA Astrophysics Data System (ADS)

    Kohl, L.; Cummings, E.; Cox, A.; Suzuki, S.; Morrrissey, L.; Lang, S. Q.; Richter, A.; Nealson, K. H.; Morrill, P. L.

    2015-12-01

    The Cedars is a complex of ultra-basic, reducing springs located in the Coastal Range Ophiolite (CA, USA), a site of present day serpentinization. Similar to other serpentinization-associated fluids, the groundwaters discharging at The Cedars contain elevated concentrations of C1-C6 alkanes and volatile organic acids (VOAs) which may originate from abiotic or thermogenic processes but can also be produced, consumed, or transformed by microbial activity. In contrast to other continental sites of serpentinization, geochemical indicators (δ13CCH4, δ2HCH4, CH4/C2-C6 alkanes) are consistent with a partial microbial origin of methane at The Cedars. These indicators, however, can provide only indirect evidence of microbial methanogenesis. To further explore the metabolic potential of the indigenous microbial communities at The Cedars, we conducted a series of microcosm experiments in which fluids and sediments collected at The Cedars were incubated with 13C labeled substrates (formate, acetate, bicarbonate, methanol) under anaerobic conditions. 13C from all amended substrates was incorporated into CH4 demonstrating that these microbial communities can convert both organic and inorganic substrates to CH4. The apparent fractionation of 13C between methane and potential substrates indicated that carbonate reduction was the dominant pathway of methanogenesis, and 16S rDNA based community profiling revealed the presence of an OTU closest related to Methanobacterium sp., an autotrophic (CO2/H2) methanogen. Concentrations of C1-C4 VOAs increased 5-fold over the course of the experiment indicating the microbial production of VOAs. This acetogenesis occurred heterotrophically as autotrophic acetogenesis can be excluded because (a) δ13C values of acetate were similar to those of inorganic carbon (inconsistent with the strong discrimination against 13C observed in autotrophic acetogenesis) and (b) no incorporation of 13C from labeled bicarbonate was into acetate was observed.

  13. Assessment of the aerobic preparation and bottom ash addition as pretreatment steps before landfilling: impact on methanogenesis kinetics and leachate parameters.

    PubMed

    Mansour, Alicia A; Motte, Antoine; Pallier, Virginie; Feuillade-Cathalifaud, Geneviève; Ponthieux, Arnaud

    2012-10-01

    This work focuses on assessing the impact of two types of waste pretreatment: addition of bottom ashes and aerobic pretreatment on both the onset and kinetics of methanogenesis and the evolution of different parameters in the leachate. It also studies the correlation between methane production and the different parameters measured in the leachate produced. A total of six 68-L pilots were thus used with fresh municipal solid waste (MSW) shredded to a 40-mm size. After 14 months of landfilling, the control has produced less than 10 NLkg(-1)DM, which corresponds to around 7% of its biochemical methane potential (BMP). Nevertheless, on one hand for aerobically pretreated waste, the lag phase before the onset of methanogenesis is significantly reduced to 0.9 month compared to more than 1 year for the control. In addition to that, on average 110 NLkg(-1)DM (90% of the BMP) is produced within around 6.5 months. On the other hand, the waste with added bottom ash shows a slight improvement of the lag phase over the control for one of the duplicate: 6.1 months of lag phase. At this stage, on average of 26 NLkg(-1)DM waste are detected (22% of the BMP) no final conclusion concerning the impact of bottom ashes could be made. The data obtained for the leachate parameters agrees with the observations on methane production. Statistical correlation study shows that the two components of the corrected PCA interpret 76% of the variability of the data: SUVA (specific UV absorbance at 254 nm) and HPI(*) (% of hydrophilic compounds) are identified as interesting parameters for following up the biodegradation in landfill conditions. PMID:22640801

  14. In vitro study and comparison of caecal methanogenesis and fermentation pattern in the brown hare (Lepus europaeus) and domestic rabbit (Oryctolagus cuniculus).

    PubMed

    Miśta, Dorota; Króliczewska, Bożena; Marounek, Milan; Pecka, Ewa; Zawadzki, Wojciech; Nicpoń, Józef

    2015-01-01

    The brown hare and the domestic rabbit are mid-sized herbivorous mammals and hindgut fermenters, though their digestive physiologies differ in some traits. The objective of this study was to estimate and compare the caecal microbial activity in hares and rabbits via an analysis of the following end-products of in vitro caecal fermentation: methane, total gas production, short chain fatty acids and ammonia concentration. Hare caecal methanogenesis occurred at a much lower level (0.25 mmol/kg for samples incubated without substrate and 0.22 mmol/kg for samples incubated with substrate) than that of the rabbit (15.49 and 11.73 mmol/kg, respectively) (P<0.001). The impact of the substrate's presence on caecal methanogenesis was not significant, though its presence increased the total gas production during fermentation (P<0.001). Hare caecal microflora produced a lower short chain fatty acids concentration than did rabbit microorganisms (P<0.05). In unincubated hare samples, the short chain fatty acids concentration was 28.4 mmol/kg, whereas in unincubated rabbit samples, the short chain fatty acids concentration was 51.8 mmol/kg. The caecal fermentation pattern of the hare was characterised by higher propionate and isobutyrate molar proportions compared with those observed in rabbit caecum (P<0.01). No significant changes in the ammonia concentration in either rabbit or hare caecum were found. The results obtained indicate some differences in the activity of the microbial populations colonising the hare and rabbit caecum, particularly in regards to methanogenic Archaea. PMID:25629411

  15. In Vitro Study and Comparison of Caecal Methanogenesis and Fermentation Pattern in the Brown Hare (Lepus europaeus) and Domestic Rabbit (Oryctolagus cuniculus)

    PubMed Central

    Miśta, Dorota; Króliczewska, Bożena; Marounek, Milan; Pecka, Ewa; Zawadzki, Wojciech; Nicpoń, Józef

    2015-01-01

    The brown hare and the domestic rabbit are mid-sized herbivorous mammals and hindgut fermenters, though their digestive physiologies differ in some traits. The objective of this study was to estimate and compare the caecal microbial activity in hares and rabbits via an analysis of the following end-products of in vitro caecal fermentation: methane, total gas production, short chain fatty acids and ammonia concentration. Hare caecal methanogenesis occurred at a much lower level (0.25 mmol/kg for samples incubated without substrate and 0.22 mmol/kg for samples incubated with substrate) than that of the rabbit (15.49 and 11.73 mmol/kg, respectively) (P<0.001). The impact of the substrate’s presence on caecal methanogenesis was not significant, though its presence increased the total gas production during fermentation (P<0.001). Hare caecal microflora produced a lower short chain fatty acids concentration than did rabbit microorganisms (P<0.05). In unincubated hare samples, the short chain fatty acids concentration was 28.4 mmol/kg, whereas in unincubated rabbit samples, the short chain fatty acids concentration was 51.8 mmol/kg. The caecal fermentation pattern of the hare was characterised by higher propionate and isobutyrate molar proportions compared with those observed in rabbit caecum (P<0.01). No significant changes in the ammonia concentration in either rabbit or hare caecum were found. The results obtained indicate some differences in the activity of the microbial populations colonising the hare and rabbit caecum, particularly in regards to methanogenic Archaea. PMID:25629411

  16. Offset Compound Gear Drive

    NASA Technical Reports Server (NTRS)

    Stevens, Mark A.; Handschuh, Robert F.; Lewicki, David G.

    2010-01-01

    The Offset Compound Gear Drive is an in-line, discrete, two-speed device utilizing a special offset compound gear that has both an internal tooth configuration on the input end and external tooth configuration on the output end, thus allowing it to mesh in series, simultaneously, with both a smaller external tooth input gear and a larger internal tooth output gear. This unique geometry and offset axis permits the compound gear to mesh with the smaller diameter input gear and the larger diameter output gear, both of which are on the same central, or primary, centerline. This configuration results in a compact in-line reduction gear set consisting of fewer gears and bearings than a conventional planetary gear train. Switching between the two output ratios is accomplished through a main control clutch and sprag. Power flow to the above is transmitted through concentric power paths. Low-speed operation is accomplished in two meshes. For the purpose of illustrating the low-speed output operation, the following example pitch diameters are given. A 5.0 pitch diameter (PD) input gear to 7.50 PD (internal tooth) intermediate gear (0.667 reduction mesh), and a 7.50 PD (external tooth) intermediate gear to a 10.00 PD output gear (0.750 reduction mesh). Note that it is not required that the intermediate gears on the offset axis be of the same diameter. For this example, the resultant low-speed ratio is 2:1 (output speed = 0.500; product of stage one 0.667 reduction and stage two 0.750 stage reduction). The design is not restricted to the example pitch diameters, or output ratio. From the output gear, power is transmitted through a hollow drive shaft, which, in turn, drives a sprag during which time the main clutch is disengaged.

  17. Base drive circuit

    DOEpatents

    Lange, A.C.

    1995-04-04

    An improved base drive circuit having a level shifter for providing bistable input signals to a pair of non-linear delays. The non-linear delays provide gate control to a corresponding pair of field effect transistors through a corresponding pair of buffer components. The non-linear delays provide delayed turn-on for each of the field effect transistors while an associated pair of transistors shunt the non-linear delays during turn-off of the associated field effect transistor. 2 figures.

  18. Modular droplet actuator drive

    NASA Technical Reports Server (NTRS)

    Pollack, Michael G. (Inventor); Paik, Philip (Inventor)

    2011-01-01

    A droplet actuator drive including a detection apparatus for sensing a property of a droplet on a droplet actuator; circuitry for controlling the detection apparatus electronically coupled to the detection apparatus; a droplet actuator cartridge connector arranged so that when a droplet actuator cartridge electronically is coupled thereto: the droplet actuator cartridge is aligned with the detection apparatus; and the detection apparatus can sense the property of the droplet on a droplet actuator; circuitry for controlling a droplet actuator coupled to the droplet actuator connector; and the droplet actuator circuitry may be coupled to a processor.

  19. Base drive circuit

    DOEpatents

    Lange, Arnold C.

    1995-01-01

    An improved base drive circuit (10) having a level shifter (24) for providing bistable input signals to a pair of non-linear delays (30, 32). The non-linear delays (30, 32) provide gate control to a corresponding pair of field effect transistors (100, 106) through a corresponding pair of buffer components (88, 94). The non-linear delays (30, 32) provide delayed turn-on for each of the field effect transistors (100, 106) while an associated pair of transistors (72, 80) shunt the non-linear delays (30, 32) during turn-off of the associated field effect transistor (100, 106).

  20. Advances in traction drive technology

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Anderson, N. E.; Rohn, D. A.

    1983-01-01

    Traction drives are traced from early uses as main transmissions in automobiles at the turn of the century to modern, high-powered traction drives capable of transmitting hundreds of horsepower. Recent advances in technology are described which enable today's traction drive to be a serious candidate for off-highway vehicles and helicopter applications. Improvements in materials, traction fluids, design techniques, power loss and life prediction methods will be highlighted. Performance characteristics of the Nasvytis fixed-ratio drive are given. Promising future drive applications, such as helicopter main transmissions and servo-control positioning mechanisms are also addressed.

  1. Glaucoma and Driving: On-Road Driving Characteristics

    PubMed Central

    Wood, Joanne M.; Black, Alex A.; Mallon, Kerry; Thomas, Ravi; Owsley, Cynthia

    2016-01-01

    Purpose To comprehensively investigate the types of driving errors and locations that are most problematic for older drivers with glaucoma compared to those without glaucoma using a standardized on-road assessment. Methods Participants included 75 drivers with glaucoma (mean = 73.2±6.0 years) with mild to moderate field loss (better-eye MD = -1.21 dB; worse-eye MD = -7.75 dB) and 70 age-matched controls without glaucoma (mean = 72.6 ± 5.0 years). On-road driving performance was assessed in a dual-brake vehicle by an occupational therapist using a standardized scoring system which assessed the types of driving errors and the locations where they were made and the number of critical errors that required an instructor intervention. Driving safety was rated on a 10-point scale. Self-reported driving ability and difficulties were recorded using the Driving Habits Questionnaire. Results Drivers with glaucoma were rated as significantly less safe, made more driving errors, and had almost double the rate of critical errors than those without glaucoma. Driving errors involved lane positioning and planning/approach, and were significantly more likely to occur at traffic lights and yield/give-way intersections. There were few between group differences in self-reported driving ability. Conclusions Older drivers with glaucoma with even mild to moderate field loss exhibit impairments in driving ability, particularly during complex driving situations that involve tactical problems with lane-position, planning ahead and observation. These results, together with the fact that these drivers self-report their driving to be relatively good, reinforce the need for evidence-based on-road assessments for evaluating driving fitness. PMID:27472221

  2. An altered form of pp60/sup c-src/ is expressed primarily in the central nervous system

    SciTech Connect

    Le Beau, J.M.; Wiestler, O.D.; Walter, G.

    1987-11-01

    The expression of two forms of pp60/sup c-scr/, pp60 and pp60/sup +/, was measured in the central nervous system (CNS) and the peripheral nervous system. Both forms were expressed in the CNS, whereas only pp60 was primarily detected in the peripheral nervous system. Our findings suggest that pp60/sup +/ may play a role in events important to the CNS.

  3. Prognostic Cell Biological Markers in Cervical Cancer Patients Primarily Treated With (Chemo)radiation: A Systematic Review

    SciTech Connect

    Noordhuis, Maartje G.; Eijsink, Jasper J.H.; Roossink, Frank; Graeff, Pauline de; Pras, Elisabeth; Schuuring, Ed; Wisman, G. Bea A.; Bock, Geertruida H. de; Zee, Ate G.J. van der

    2011-02-01

    The aim of this study was to systematically review the prognostic and predictive significance of cell biological markers in cervical cancer patients primarily treated with (chemo)radiation. A PubMed, Embase, and Cochrane literature search was performed. Studies describing a relation between a cell biological marker and survival in {>=}50 cervical cancer patients primarily treated with (chemo)radiation were selected. Study quality was assessed, and studies with a quality score of 4 or lower were excluded. Cell biological markers were clustered on biological function, and the prognostic and predictive significance of these markers was described. In total, 42 studies concerning 82 cell biological markers were included in this systematic review. In addition to cyclooxygenase-2 (COX-2) and serum squamous cell carcinoma antigen (SCC-ag) levels, markers associated with poor prognosis were involved in epidermal growth factor receptor (EGFR) signaling (EGFR and C-erbB-2) and in angiogenesis and hypoxia (carbonic anhydrase 9 and hypoxia-inducible factor-1{alpha}). Epidermal growth factor receptor and C-erbB-2 were also associated with poor response to (chemo)radiation. In conclusion, EGFR signaling is associated with poor prognosis and response to therapy in cervical cancer patients primarily treated with (chemo)radiation, whereas markers involved in angiogenesis and hypoxia, COX-2, and serum SCC-ag levels are associated with a poor prognosis. Therefore, targeting these pathways in combination with chemoradiation may improve survival in advanced-stage cervical cancer patients.

  4. Landscape heritage objects' effect on driving: a combined driving simulator and questionnaire study.

    PubMed

    Antonson, Hans; Ahlström, Christer; Mårdh, Selina; Blomqvist, Göran; Wiklund, Mats

    2014-01-01

    According to the literature, landscape (panoramas, heritage objects e.g. landmarks) affects people in various ways. Data are primarily developed by asking people (interviews, photo sessions, focus groups) about their preferences, but to a lesser degree by measuring how the body reacts to such objects. Personal experience while driving a car through a landscape is even more rare. In this paper we study how different types of objects in the landscape affect drivers during their drive. A high-fidelity moving-base driving simulator was used to measure choice of speed and lateral position in combination with stress (heart rate measure) and eye tracking. The data were supplemented with questionnaires. Eighteen test drivers (8 men and 10 women) with a mean age of 37 were recruited. The test drivers were exposed to different new and old types of landscape objects such as 19th century church, wind turbine, 17th century milestone and bus stop, placed at different distances from the road driven. The findings are in some respect contradictory, but it was concluded that that 33% of the test drivers felt stressed during the drive. All test drivers said that they had felt calm at times during the drive but the reason for this was only to a minor degree connected with old and modern objects. The open landscape was experienced as conducive to acceleration. Most objects were, to a small degree, experienced (subjective data) as having a speed-reducing effect, much in line with the simulator data (objective data). Objects close to the road affected the drivers' choice of' lateral position. No significant differences could be observed concerning the test drivers' gaze between old or modern objects, but a significant difference was observed between the test drivers' gaze between road stretches with faraway objects and stretches without objects. No meaningful, significant differences were found for the drivers' stress levels as measured by heart rate. PMID:24172083

  5. Experiment study on friction drive

    NASA Astrophysics Data System (ADS)

    Wang, Guomin; Ma, Lisheng; Yao, Zhengqiu; Li, Guoping

    2004-09-01

    In the past years, friction drive was developed to overcome the inherent deficiencies in both worm drive and gear drive. No periodical error and free of backlash are the main advantages of friction drive. With the trend towards bigger and bigger aperture of the optical telescopes, there are some reports about friction drive employed to drive the telescopes. However friction drive has its own deficiencies, such as slippage and creepage. This report here describes the study on the friction drive finished in an experiment arranged by LAMOST project. It comprises three main parts. First, it introduces the experiment apparatus and proposes a new kind of measurement and adjustment mechanisms. Secondly, the report gives the analysis of friction drive characteristics theoretically, such as slippage, creepage and gives the results of corresponding experiments. The experiment shows that the lowest stable speed reaches 0.05″/s with precision of 0.009″(RMS), the preload has little influence on the drive precision in the case of constant velocity and the variable velocity when the angle acceleration is less than 5″/s2 with close loop control and the creepage velocity of this experiment system is 1.47″/s. Lastly, the analysis in the second section lists some measures to improve the precision and stability further. These measures have been actually conducted in the testing system and proved to be reliable.

  6. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1992-01-01

    A new rare earth alloy, Terfenol-D, combines low frequency operation and extremely high energy density with high magnetostriction. Its material properties make it suitable as a drive element for actuators requiring high output torque. The high strains, the high forces and the high controllability of Terfenol alloys provide a powerful and challenging basis for new ways to generate motion in actuators. Two prototypes of motors using Terfenol-D rods were developed at NASA Goddard. The basic principles of operation are provided of the motor along with other relevant details. A conceptual design of a torque limiting safety clutch/brake under development is illustrated. Also, preliminary design drawings of a linear actuator using Terfenol-D is shown.

  7. Automatism and driving offences.

    PubMed

    Rumbold, John

    2013-10-01

    Automatism is a rarely used defence, but it is particularly used for driving offences because many are strict liability offences. Medical evidence is almost always crucial to argue the defence, and it is important to understand the bars that limit the use of automatism so that the important medical issues can be identified. The issue of prior fault is an important public safeguard to ensure that reasonable precautions are taken to prevent accidents. The total loss of control definition is more problematic, especially with disorders of more gradual onset like hypoglycaemic episodes. In these cases the alternative of 'effective loss of control' would be fairer. This article explores several cases, how the criteria were applied to each, and the types of medical assessment required. PMID:24112330

  8. QUICK RELEASABLE DRIVE

    DOEpatents

    Dickson, J.J.

    1958-07-01

    A quick releasable mechanical drive system suitable for use in a nuclear reactor is described. A small reversible motor positions a control rod by means of a worm and gear speed reducer, a magnetic torque clutch, and a bell crank. As the control rod is raised to the operating position, a heavy coil spring is compressed. In the event of an emergency indicated by either a''scram'' signal or a power failure, the current to the magnetic clutch is cut off, thereby freeing the coil spring and the bell crank positioner from the motor and speed reduction gearing. The coil spring will immediately act upon the bell crank to cause the insertion of the control rod. This arrangement will allow the slow, accurate positioning of the control rod during reactor operation, while providing an independent force to rapidly insert the rod in the event of an emergency.

  9. Head tilt during driving.

    PubMed

    Zikovitz, D C; Harris, L R

    1999-05-01

    In order to distinguish between the use of visual and gravito-inertial force reference frames, the head tilt of drivers and passengers were measured as they went around corners at various speeds. The visual curvature of the corners were thus dissociated from the magnitude of the centripetal forces (0.30-0.77 g). Drivers' head tilts were highly correlated with the visually-available estimate of the curvature of the road (r2=0.86) but not with the centripetal force (r2<0.1). Passengers' head tilts were inversely correlated with the lateral forces (r2=0.3-0.7) and seem to reflect a passive sway. The strong correlation of the tilt of drivers' heads with a visual aspect of the road ahead, supports the use of a predominantly visual reference frame for the driving task. PMID:10722313

  10. All wheel drive vehicle

    SciTech Connect

    Watanabe, M.; Yagasaki, A.; Kawashima, Y.

    1986-07-15

    An all-wheel-drive vehicle is described which consists of: (a) a body; (b) an engine mounted on the body and having an output shaft; (c) front and rear pairs of wheels drivable by power from the engine, the front and rear wheels being vertically movably suspended from the body; (d) axles coupled to the front and rear wheels; (e) first power transmitting means for transmitting power from the output shaft of the engine to one of the axles of the front and rear wheels; (f) a power output unit mounted on the one axle; and (g) second power transmitting means for transmitting power from the power output unit to the other of the axles of the front and rear wheels.

  11. Rotary drive mechanism

    DOEpatents

    Kenderdine, Eugene W.

    1991-01-01

    A rotary drive mechanism includes a rotary solenoid having a stator and multi-poled rotor. A moving member rotates with the rotor and is biased by a biasing device. The biasing device causes a further rotational movement after rotation by the rotary solenoid. Thus, energization of the rotary solenoid moves the member in one direction to one position and biases the biasing device against the member. Subsequently, de-energization of the rotary solenoid causes the biasing device to move the member in the same direction to another position from where the moving member is again movable by energization and de-energization of the rotary solenoid. Preferably, the moving member is a multi-lobed cam having the same number of lobes as the rotor has poles. An anti-overdrive device is also preferably provided for preventing overdrive in the forward direction or a reverse rotation of the moving member and for precisely aligning the moving member.

  12. Hyperactive children as young adults: driving abilities, safe driving behavior, and adverse driving outcomes.

    PubMed

    Fischer, Mariellen; Barkley, Russell A; Smallish, Lori; Fletcher, Kenneth

    2007-01-01

    ADHD has been linked to poorer driving abilities and greater adverse outcomes (crashes, citations) in clinic-referred cases of teens and adults with ADHD. No study, however, has focused systematically on ADHD children followed into adulthood. The present paper does so while measuring driving-related cognitive abilities, driving behavior, and history of adverse driving outcomes. A multi-method, multi-source battery of driving measures was collected at the young adult follow-up on hyperactive (H; N=147; mean age=21.1) and community control children (CC; N=71; mean age=20.5) followed for more than 13 years. More of the H than CC groups had been ticketed for reckless driving, driving without a license, hit-and-run crashes, and had their licenses suspended or revoked. Official driving records found more of the H group having received traffic citations and a greater frequency of license suspensions. The cost of damage in their initial crashes was also significantly greater in the H than CC group. Both self-report and other ratings of actual driving behavior revealed less safe driving practices being used by the H group. Observations by driving instructors during a behind-the-wheel road test indicated significantly more impulsive errors. Performance on a simulator further revealed slower and more variable reaction times, greater errors of impulsiveness (false alarms, poor rule following), more steering variability, and more scrapes and crashes of the simulated vehicle against road boundaries in the H than in the CC group. These findings suggest that children growing up with ADHD may either have fewer driving risks or possibly under-report those risks relative to clinic-referred adults with this disorder. Deficits in simulator performance and safe driving behavior, however, are consistent with clinic-referred adults with ADHD suggesting ongoing risks for such adverse driving outcomes in children growing up with ADHD. PMID:16919226

  13. Dimensions of driving anger and their relationships with aberrant driving.

    PubMed

    Zhang, Tingru; Chan, Alan H S; Zhang, Wei

    2015-08-01

    The purpose of this study was to investigate the relationship between driving anger and aberrant driving behaviours. An internet-based questionnaire survey was administered to a sample of Chinese drivers, with driving anger measured by a 14-item short Driving Anger Scale (DAS) and the aberrant driving behaviours measured by a 23-item Driver Behaviour Questionnaire (DBQ). The results of Confirmatory Factor Analysis demonstrated that the three-factor model (hostile gesture, arrival-blocking and safety-blocking) of the DAS fitted the driving anger data well. The Exploratory Factor Analysis on DBQ data differentiated four types of aberrant driving, viz. emotional violation, error, deliberate violation and maintaining progress violation. For the anger-aberration relation, it was found that only "arrival-blocking" anger was a significant positive predictor for all four types of aberrant driving behaviours. The "safety-blocking" anger revealed a negative impact on deliberate violations, a finding different from previously established positive anger-aberration relation. These results suggest that drivers with different patterns of driving anger would show different behavioural tendencies and as a result intervention strategies may be differentially effective for drivers of different profiles. PMID:25984643

  14. Wall relaxation and the driving forces for cell expansive growth

    NASA Technical Reports Server (NTRS)

    Cosgrove, D. J.

    1987-01-01

    When water uptake by growing cells is prevented, the turgor pressure and the tensile stress in the cell wall are reduced by continued wall loosening. This process, termed in vivo stress relaxation, provides a new way to study the dynamics of wall loosening and to measure the wall yield threshold and the physiological wall extensibility. Stress relaxation experiments indicate that wall stress supplies the mechanical driving force for wall yielding. Cell expansion also requires water absorption. The driving force for water uptake during growth is created by wall relaxation, which lowers the water potential of the expanding cells. New techniques for measuring this driving force show that it is smaller than believed previously; in elongating stems it is only 0.3 to 0.5 bar. This means that the hydraulic resistance of the water transport pathway is small and that rate of cell expansion is controlled primarily by wall loosening and yielding.

  15. Sequenced drive for rotary valves

    DOEpatents

    Mittell, Larry C.

    1981-01-01

    A sequenced drive for rotary valves which provides the benefits of applying rotary and linear motions to the movable sealing element of the valve. The sequenced drive provides a close approximation of linear motion while engaging or disengaging the movable element with the seat minimizing wear and damage due to scrubbing action. The rotary motion of the drive swings the movable element out of the flowpath thus eliminating obstruction to flow through the valve.

  16. Sizing criterial for traction drives

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.; Coy, J. J.

    1983-01-01

    A simplified traction drive fatigue analysis which was derived from the Lundberg-Palmgren theory is measured and the effects of rotational speed, multiplicity of contacts, and variation in the available traction coefficient on traction drive system life, size, and power capacity was investigated. Simplified equations are provided for determining the 90% survival life rating of steel traction drive contacts of arbitrary geometry. References to life modifying factors for material, lubrication, and traction will be made.

  17. The drive-wise project: driving simulator training increases real driving performance in healthy older drivers

    PubMed Central

    Casutt, Gianclaudio; Theill, Nathan; Martin, Mike; Keller, Martin; Jäncke, Lutz

    2014-01-01

    Background: Age-related cognitive decline is often associated with unsafe driving behavior. We hypothesized that 10 active training sessions in a driving simulator increase cognitive and on-road driving performance. In addition, driving simulator training should outperform cognitive training. Methods: Ninety-one healthy active drivers (62–87 years) were randomly assigned to one of three groups: (1) a driving simulator training group, (2) an attention training group (vigilance and selective attention), or (3) a control group. The main outcome variables were on-road driving and cognitive performance. Seventy-seven participants (85%) completed the training and were included in the analyses. Training gains were analyzed using a multiple regression analysis with planned orthogonal comparisons. Results: The driving simulator-training group showed an improvement in on-road driving performance compared to the attention-training group. In addition, both training groups increased cognitive performance compared to the control group. Conclusion: Driving simulator training offers the potential to enhance driving skills in older drivers. Compared to the attention training, the simulator training seems to be a more powerful program for increasing older drivers' safety on the road. PMID:24860497

  18. Driving anger in Ukraine: Appraisals, not trait driving anger, predict anger intensity while driving.

    PubMed

    Stephens, A N; Hill, T; Sullman, M J M

    2016-03-01

    Trait driving anger is often, but not always, found to predict both the intensity of anger while driving and subsequent crash-related behaviours. However, a number of studies have not found support for a direct relationship between one's tendency to become angry and anger reported while driving, suggesting that other factors may mediate this relationship. The present self-report study investigated whether, in anger provoking driving situations, the appraisals made by drivers influence the relationship between trait and state anger. A sample of 339 drivers from Ukraine completed the 33-item version of the Driver Anger Scale (DAS; Deffenbacher et al., 1994) and eight questions about their most recent experience of driving anger. A structural equation model found that the intensity of anger experienced was predicted by the negative evaluations of the situation, which was in turn predicted by trait driving anger. However, trait driving anger itself did not predict anger intensity; supporting the hypothesis that evaluations of the driving situation mediate the relationship between trait and state anger. Further, the unique structure of the DAS required to fit the data from the Ukrainian sample, may indicate that the anger inducing situations in Ukraine are different to those of a more developed country. Future research is needed to investigate driving anger in Ukraine in a broader sample and also to confirm the role of the appraisal process in the development of driving anger in both developed and undeveloped countries. PMID:26710267

  19. 26. CAN CONVEYOR DRIVE MECHANISM Empty can conveyor driving mechanism, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    26. CAN CONVEYOR DRIVE MECHANISM Empty can conveyor driving mechanism, second floor above canning area. The belt has been removed from the conveyor, but sections of can conveyor tracks are visible on the floor. - Hovden Cannery, 886 Cannery Row, Monterey, Monterey County, CA

  20. VIEW OF BEND IN CEDAR DRIVE WITH 603 CEDAR DRIVE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    VIEW OF BEND IN CEDAR DRIVE WITH 603 CEDAR DRIVE ON RIGHT. VIEW FACING NORTHEAST - Camp H.M. Smith and Navy Public Works Center Manana Title VII (Capehart) Housing, Intersection of Acacia Road and Brich Circle, Pearl City, Honolulu County, HI

  1. [Facial pain- a rare cause. Impacted lower third molars causing primarily "unclear" facial pain: a case report].

    PubMed

    Gander, Thomas; Dagassan-Berndt, Dorothea; Mascolo, Luana; Kruse, Astrid L; Grätz, Klaus W; Lübbers, Heinz-Theo

    2013-01-01

    Orofacial pain often causes special difficulties to patients and dentists. Numerous differential diagnoses require the utilization of a coordinated diagnostic concept. Often, multiple causes lead to the need for a complex treatment plan. Impacted third molars are a potential cause of a variety of complications. Caries, pulp necrosis, and periapical infection are some of the infrequent causes of such pain. The presented case shows just such a constellation, resulting in primarily "unclear" orofacial pain. A diagnostic sequence generally leads to the correct diagnosis and thereby allows for fast and effective therapy. This shows how important structured diagnostics are, especially in cases of "unclear" pain. PMID:24114596

  2. Utilization of subsurface microbial electrochemical systems to elucidate the mechanisms of competition between methanogenesis and microbial iron(III)/humic acid reduction in Arctic peat soils

    NASA Astrophysics Data System (ADS)

    Friedman, E. S.; Miller, K.; Lipson, D.; Angenent, L. T.

    2012-12-01

    High-latitude peat soils are a major carbon reservoir, and there is growing concern that previously dormant carbon from this reservoir could be released to the atmosphere as a result of continued climate change. Microbial processes, such as methanogenesis and carbon dioxide production via iron(III) or humic acid reduction, are at the heart of the carbon cycle in Arctic peat soils [1]. A deeper understanding of the factors governing microbial dominance in these soils is crucial for predicting the effects of continued climate change. In previous years, we have demonstrated the viability of a potentiostatically-controlled subsurface microbial electrochemical system-based biosensor that measures microbial respiration via exocellular electron transfer [2]. This system utilizes a graphite working electrode poised at 0.1 V NHE to mimic ferric iron and humic acid compounds. Microbes that would normally utilize these compounds as electron acceptors donate electrons to the electrode instead. The resulting current is a measure of microbial respiration with the electrode and is recorded with respect to time. Here, we examine the mechanistic relationship between methanogenesis and iron(III)- or humic acid-reduction by using these same microbial-three electrode systems to provide an inexhaustible source of alternate electron acceptor to microbes in these soils. Chamber-based carbon dioxide and methane fluxes were measured from soil collars with and without microbial three-electrode systems over a period of four weeks. In addition, in some collars we simulated increased fermentation by applying acetate treatments to understand possible effects of continued climate change on microbial processes in these carbon-rich soils. The results from this work aim to increase our fundamental understanding of competition between electron acceptors, and will provide valuable data for climate modeling scenarios. 1. Lipson, D.A., et al., Reduction of iron (III) and humic substances plays a major

  3. Water deficit in field-grown Gossypium hirsutum primarily limits net photosynthesis by decreasing stomatal conductance, increasing photorespiration, and increasing the ratio of dark respiration to gross photosynthesis.

    PubMed

    Chastain, Daryl R; Snider, John L; Collins, Guy D; Perry, Calvin D; Whitaker, Jared; Byrd, Seth A

    2014-11-01

    Much effort has been expended to improve irrigation efficiency and drought tolerance of agronomic crops; however, a clear understanding of the physiological mechanisms that interact to decrease source strength and drive yield loss has not been attained. To elucidate the underlying mechanisms contributing to inhibition of net carbon assimilation under drought stress, three cultivars of Gossypium hirsutum were grown in the field under contrasting irrigation regimes during the 2012 and 2013 growing season near Camilla, Georgia, USA. Physiological measurements were conducted on three sample dates during each growing season (providing a broad range of plant water status) and included, predawn and midday leaf water potential (ΨPD and ΨMD), gross and net photosynthesis, dark respiration, photorespiration, and chlorophyll a fluorescence. End-of-season lint yield was also determined. ΨPD ranged from -0.31 to -0.95MPa, and ΨMD ranged from -1.02 to -2.67MPa, depending upon irrigation regime and sample date. G. hirsutum responded to water deficit by decreasing stomatal conductance, increasing photorespiration, and increasing the ratio of dark respiration to gross photosynthesis, thereby limiting PN and decreasing lint yield (lint yield declines observed during the 2012 growing season only). Conversely, even extreme water deficit, causing a 54% decline in PN, did not negatively affect actual quantum yield, maximum quantum yield, or photosynthetic electron transport. It is concluded that PN is primarily limited in drought-stressed G. hirsutum by decreased stomatal conductance, along with increases in respiratory and photorespiratory carbon losses, not inhibition or down-regulation of electron transport through photosystem II. It is further concluded that ΨPD is a reliable indicator of drought stress and the need for irrigation in field-grown cotton. PMID:25151126

  4. FADD Expression as a Prognosticator in Early-Stage Glottic Squamous Cell Carcinoma of the Larynx Treated Primarily With Radiotherapy

    SciTech Connect

    Schrijvers, Michiel L.; Pattje, Wouter J.; Slagter-Menkema, Lorian; Mastik, Mirjam F.; Gibcus, Johan H.; Langendijk, Johannes A.; Wal, Jacqueline E. van der; Laan, Bernard F.A.M. vn der

    2012-07-15

    Purpose: We recently reported on the identification of the Fas-associated death domain (FADD) as a possible driver of the chromosome 11q13 amplicon and the association between increased FADD expression and disease-specific survival in advanced-stage laryngeal carcinoma. The aim of this study was to examine whether expression of FADD and its Ser194-phosphorylated isoform (pFADD) predicts local control in patients with early-stage glottic carcinoma primarily treated with radiotherapy only. Methods and Materials: Immunohistochemical staining for FADD and pFADD was performed on pretreatment biopsy specimens of 92 patients with T1-T2 glottic squamous cell carcinoma primarily treated with radiotherapy between 1996 and 2005. Cox regression analysis was used to correlate expression levels with local control. Results: High levels of pFADD were associated with significantly better local control (hazard ratio, 2.40; 95% confidence interval, 1.04-5.55; p = 0.040). FADD overexpression showed a trend toward better local control (hazard ratio, 3.656; 95% confidence interval, 0.853-15.663; p = 0.081). Multivariate Cox regression analysis showed that high pFADD expression was the best predictor of local control after radiotherapy. Conclusions: This study showed that expression of phosphorylated FADD is a new prognostic biomarker for better local control after radiotherapy in patients with early-stage glottic carcinomas.

  5. Borrelia burgdorferi Oxidative Stress Regulator BosR Directly Represses Lipoproteins Primarily Expressed in the Tick during Mammalian Infection

    PubMed Central

    Wang, Peng; Dadhwal, Poonam; Cheng, Zhihui; Zianni, Michael R.; Rikihisa, Yasuko; Liang, Fang Ting; Li, Xin

    2013-01-01

    Summary Differential gene expression is a key strategy adopted by the Lyme disease spirochaete, Borrelia burgdorferi, for adaptation and survival in the mammalian host and the tick vector. Many B. burgdorferi surface lipoproteins fall into two distinct groups according to their expression patterns: one group primarily expressed in the tick and the other group primarily expressed in the mammal. Here, we show that the Fur homologue in this bacterium, also known as Borrelia oxidative stress regulator (BosR), is required for repression of outer surface protein A (OspA) and OspD in the mammal. Furthermore, BosR binds directly to sequences upstream of the ospAB operon and the ospD gene through recognition of palindromic motifs similar to those recognized by other Fur homologues but with a 1-bp variation in the spacer length. Putative BosR-binding sites have been identified upstream of 156 B. burgdorferi genes. Some of these genes share the same expression pattern as ospA and ospD. Most notably, 12 (67%) of the 18 genes previously identified in a genome-wide microarray study to be most significantly repressed in the mammal are among the putative BosR regulon. These data indicate that BosR may directly repress transcription of many genes that are down-regulated in the mammal. PMID:23869590

  6. Methanogenesis from methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in the sediments of a eutrophic lake

    SciTech Connect

    Lovley, D.R.; Klug, M.J.

    1983-04-01

    /sup 14/C-tracer techniques were used to examine the metabolism of methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in sediments from the profundal and littoral zones of eutrophic Wintergreen Lake, Michigan. Methanogens were primarily responsible for the metabolism of methanol, mono-methylammine, and trimethylamine and maintained the pool size of these substrates below 10 ..mu..M in both sediment types. Methanol and methylamines were the precursors for less than 5 and 1%, respectively, of the total methane produced. Methanol and methylamines continued to be metabolized to methane when the sulfate concentration in the sediment was increased to 20 mM. Less than 2% of the total acetate production was derived from carbon dioxide reduction. Hydrogen consumption by hydrogen-oxidizing acetogens was 5% or less of the total hydrogen uptake by acetogens and methanogens. These results, in conjunction with previous studies, emphasize that acetate and hydrogen are the major methane precursors and that methanogens are the predominant hydrogen consumers in the sediments of this eutrophic lake.

  7. Methanogenesis from methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in the sediments of a eutrophic lake.

    PubMed

    Lovley, D R; Klug, M J

    1983-04-01

    C-tracer techniques were used to examine the metabolism of methanol and methylamines and acetogenesis from hydrogen and carbon dioxide in sediments from the profundal and littoral zones of eutrophic Wintergreen Lake, Michigan. Methanogens were primarily responsible for the metabolism of methanol, monomethylamine, and trimethylamine and maintained the pool size of these substrates below 10 muM in both sediment types. Methanol and methylamines were the precursors for less than 5 and 1%, respectively, of the total methane produced. Methanol and methylamines continued to be metabolized to methane when the sulfate concentration in the sediment was increased to 20 mM. Less than 2% of the total acetate production was derived from carbon dioxide reduction. Hydrogen consumption by hydrogen-oxidizing acetogens was 5% or less of the total hydrogen uptake by acetogens and methanogens. These results, in conjunction with previous studies, emphasize that acetate and hydrogen are the major methane precursors and that methanogens are the predominant hydrogen consumers in the sediments of this eutrophic lake. PMID:16346271

  8. Handbook for Driving Knowledge Testing.

    ERIC Educational Resources Information Center

    Pollock, William T.; McDole, Thomas L.

    Materials intended for driving knowledge test development for use by operational licensing and education agencies are presented. A pool of 1,313 multiple choice test items is included, consisting of sets of specially developed and tested items covering principles of safe driving, legal regulations, and traffic control device knowledge pertinent to…

  9. Bidirectional drive and brake mechanism

    NASA Technical Reports Server (NTRS)

    Swan, Scott A. (Inventor)

    1991-01-01

    A space transport vehicle is disclosed as including a body which is arranged to be movably mounted on an elongated guide member disposed in outer space and driven therealong. A drive wheel is mounted on a drive shaft and arranged to be positioned in rolling engagement with the elongated guide carrying the vehicle. A brake member is arranged on the drive shaft for movement into and out of engagement with an adjacent surface of the drive wheel. An actuator is mounted on the body to be manually moved back and forth between spaced positions in an arc of movement. A ratchet-and-pawl mechanism is arranged to operate upon movements of the actuator in one direction between first and second positions for coupling the actuator to the drive wheel to incrementally rotate the wheel in one rotational direction and to operate upon movements of the actuator in the opposite direction for uncoupling the actuator from the wheel. The brake member is threadedly coupled to the drive shaft in order that the brake member will be operated only when the actuator is moved on beyond its first and second positions for shifting the brake member along the drive shaft and into frictional engagement with the adjacent surface on the drive wheel.

  10. Students: You... Alcohol and Driving.

    ERIC Educational Resources Information Center

    Department of Transportation, Washington, DC.

    The purpose of this manual is to provide accurate information about alcohol and about drinking and driving, so that the student may make responsible decisions about both. It covers youth drinking, drinking and driving, and the individual's responsibility to others in drinking situations. The booklet consists of eight readings, as well as…

  11. Driving difficulties in Parkinson's disease

    PubMed Central

    Rizzo, Matthew; Uc, Ergun Y; Dawson, Jeffrey; Anderson, Steven; Rodnitzky, Robert

    2011-01-01

    Safe driving requires the coordination of attention, perception, memory, motor and executive functions (including decision-making) and self-awareness. PD and other disorders may impair these abilities. Because age or medical diagnosis alone is often an unreliable criterion for licensure, decisions on fitness to drive should be based on empirical observations of performance. Linkages between cognitive abilities measured by neuropsychological tasks, and driving behavior assessed using driving simulators, and natural and naturalistic observations in instrumented vehicles, can help standardize the assessment of fitness-to-drive. By understanding the patterns of driver safety errors that cause crashes, it may be possible to design interventions to reduce these errors and injuries and increase mobility. This includes driver performance monitoring devices, collision alerting and warning systems, road design, and graded licensure strategies. PMID:20187237

  12. [Driving and health at work].

    PubMed

    Giorgio, Marie-Thérèse

    2015-09-01

    The role of the occupational physician is to prevent occupational accidents and diseases. Therefore, he is the one to decide if a worker is fit to drive in the context of his professional activity, including in cases where no specific driving license is required (e.g. forklift truck, mobile crane). This decision is an important one, as two thirds of fatal occupational accidents occur on the road. The decision is made on the basis of both a medical examination and the regulation, which indicates all contraindications to driving. The physician's responsibility is involved, as is the employer's, as he must ensure that his employee is fit to drive and possesses a valid driving license at all times. PMID:25960440

  13. Quantum gates by periodic driving

    PubMed Central

    Shi, Z. C.; Wang, W.; Yi, X. X.

    2016-01-01

    Topological quantum computation has been extensively studied in the past decades due to its robustness against decoherence. One way to realize the topological quantum computation is by adiabatic evolutions—it requires relatively long time to complete a gate, so the speed of quantum computation slows down. In this work, we present a method to realize single qubit quantum gates by periodic driving. Compared to adiabatic evolution, the single qubit gates can be realized at a fixed time much shorter than that by adiabatic evolution. The driving fields can be sinusoidal or square-well field. With the sinusoidal driving field, we derive an expression for the total operation time in the high-frequency limit, and an exact analytical expression for the evolution operator without any approximations is given for the square well driving. This study suggests that the period driving could provide us with a new direction in regulations of the operation time in topological quantum computation. PMID:26911900

  14. Driving the Landscape

    NASA Astrophysics Data System (ADS)

    Haff, P. K.

    2012-12-01

    Technological modification of the earth's surface (e.g., agriculture, urbanization) is an old story in human history, but what about the future? The future of landscape in an accelerating technological world, beyond a relatively short time horizon, lies hidden behind an impenetrable veil of complexity. Sufficiently complex dynamics generates not only the trajectory of a variable of interest (e.g., vegetation cover) but also the environment in which that variable evolves (e.g., background climate). There is no way to anticipate what variables will define that environment—the dynamics creates its own variables. We are always open to surprise by a change of conditions we thought or assumed were fixed or by the appearance of new phenomena of whose possible existence we had been unaware or thought unlikely. This is especially true under the influence of technology, where novelty is the rule. Lack of direct long-term predictability of landscape change does not, however, mean we cannot say anything about its future. The presence of persistence (finite time scales) in a system means that prediction by a calibrated numerical model should be good for a limited period of time barring bad luck or faulty implementation. Short-term prediction, despite its limitations, provides an option for dealing with the longer-term future. If a computer-controlled car tries to drive itself from New York to Los Angeles, no conceivable (or possible) stand-alone software can be constructed to predict a priori the space-time trajectory of the vehicle. Yet the drive is normally completed easily by most drivers. The trip is successfully completed because each in a series of very short (linear) steps can be "corrected" on the fly by the driver, who takes her cues from the environment to keep the car on the road and headed toward its destination. This metaphor differs in a fundamental way from the usual notion of predicting geomorphic change, because it involves a goal—to reach a desired

  15. Electric vehicle drive systems

    NASA Astrophysics Data System (ADS)

    Appleyard, M.

    1992-01-01

    New legislation in the State of California requires that 2% of vehicles sold there from 1998 will be 'zero-emitting'. This provides a unique market opportunity for developers of electric vehicles but substantial improvements in the technology are probably required if it is to be successfully exploited. There are around a dozen types of battery that are potentially relevant to road vehicles but, at the present, lead/acid and sodium—sulphur come closest to combining acceptable performance, life and cost. To develop an efficient, lightweight electric motor system requires up-to-date techniques of magnetics design, and the latest power-electronic and microprocessor control methods. Brushless machines, coupled with solid-state inverters, offer the most economical solution for mass production, even though their development costs are higher than for direct-current commutator machines. Fitted to a small car, even the highest energy-density batteries will only provide around 200 km average range before recharging. Therefore, some form of supplementary on-board power generation will probably be needed to secure widespread acceptance by the driving public. Engine-driven generators of quite low power can achieve useful increases in urban range but will fail to qualify as 'zero-emitting'. On the other hand, if the same function could be economically performed by a small fuel-cell using hydrogen derived from a methanol reformer, then most of the flexibility provided by conventional vehicles would be retained. The market prospects for electric cars would then be greatly enhanced and their dependence on very advanced battery technology would be reduced.

  16. SYSTEMATIC ANALYSIS OF REAL-WORLD DRIVING BEHAVIOR FOLLOWING FOCAL BRAIN LESIONS

    PubMed Central

    Thompson, Kelsey; Read, Katherine; Anderson, Steven; Rizzo, Matthew

    2012-01-01

    Summary Many patients with circumscribed brain injuries, such as those caused by stroke or focal trauma, return to driving after a period of acute recovery. These persons often have chronic residual cognitive deficits that may impact on driving safety, but little is known about their driving behavior in the real world. Extant studies tend to rely on driving simulators or controlled on-road drives. These methods of observation are not able to capture the complexities of the typical driving environment, and may not accurately represent a driver’s usual behavior on the road. The current study used a video event-activated data recorder (VEADR) system to observe drivers with focal brain lesions in their normal daily driving environment over a three-month period. In the context of primarily safe driving behavior, we were able to document a number of relatively infrequent and hitherto unobserved high risk behaviors and traffic violations. These findings demonstrate the feasibility and value of sampling real-world driving in neurologic patient populations such as those with focal brain lesions, and highlight the critical importance of evaluating unsafe driving behaviors which may occur with insufficient frequency to be captured by relatively brief simulator or controlled on-road evaluations. PMID:25309966

  17. Linear Back-Drive Differentials

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

    Linear back-drive differentials have been proposed as alternatives to conventional gear differentials for applications in which there is only limited rotational motion (e.g., oscillation). The finite nature of the rotation makes it possible to optimize a linear back-drive differential in ways that would not be possible for gear differentials or other differentials that are required to be capable of unlimited rotation. As a result, relative to gear differentials, linear back-drive differentials could be more compact and less massive, could contain fewer complex parts, and could be less sensitive to variations in the viscosities of lubricants. Linear back-drive differentials would operate according to established principles of power ball screws and linear-motion drives, but would utilize these principles in an innovative way. One major characteristic of such mechanisms that would be exploited in linear back-drive differentials is the possibility of designing them to drive or back-drive with similar efficiency and energy input: in other words, such a mechanism can be designed so that a rotating screw can drive a nut linearly or the linear motion of the nut can cause the screw to rotate. A linear back-drive differential (see figure) would include two collinear shafts connected to two parts that are intended to engage in limited opposing rotations. The linear back-drive differential would also include a nut that would be free to translate along its axis but not to rotate. The inner surface of the nut would be right-hand threaded at one end and left-hand threaded at the opposite end to engage corresponding right- and left-handed threads on the shafts. A rotation and torque introduced into the system via one shaft would drive the nut in linear motion. The nut, in turn, would back-drive the other shaft, creating a reaction torque. Balls would reduce friction, making it possible for the shaft/nut coupling on each side to operate with 90 percent efficiency.

  18. Outbreak of Serogroup C Meningococcal Disease Primarily Affecting Men Who Have Sex with Men - Southern California, 2016.

    PubMed

    Nanduri, Srinivas; Foo, Chelsea; Ngo, Van; Jarashow, Claire; Civen, Rachel; Schwartz, Ben; Holguin, John; Shearer, Eric; Zahn, Matt; Harriman, Kathleen; Winter, Kathleen; Kretz, Cecilia; Chang, How Yi; Meyer, Sarah; MacNeil, Jessica

    2016-01-01

    During March 4-August 11, 2016, 25 outbreak-associated cases of meningococcal disease, including two deaths (8% case-fatality ratio), were reported in Southern California. Twenty-four of the cases were caused by serogroup C Neisseria meningitidis (NmC) and one by N. meningitidis with an undetermined serogroup (Figure). On June 24, 2016, in response to this increase in NmC cases, primarily among men who have sex with men (MSM) in Los Angeles County, the city of Long Beach, and Orange County, the California Department of Public Health (CDPH) issued a press release and health advisory, declaring an outbreak of NmC in Southern California (1). PMID:27606798

  19. Due to intravascular multiple sequential scattering, Diffuse Correlation Spectroscopy of tissue primarily measures relative red blood cell motion within vessels.

    PubMed

    Carp, Stefan A; Roche-Labarbe, Nadàege; Franceschini, Maria-Angela; Srinivasan, Vivek J; Sakadžić, Sava; Boas, David A

    2011-07-01

    We suggest that Diffuse Correlation Spectroscopy (DCS) measurements of tissue blood flow primarily probe relative red blood cell (RBC) motion, due to the occurrence of multiple sequential scattering events within blood vessels. The magnitude of RBC shear-induced diffusion is known to correlate with flow velocity, explaining previous reports of linear scaling of the DCS "blood flow index" with tissue perfusion despite the observed diffusion-like auto-correlation decay. Further, by modeling RBC mean square displacement using a formulation that captures the transition from ballistic to diffusive motion, we improve the fit to experimental data and recover effective diffusion coefficients and velocity de-correlation time scales in the range expected from previous blood rheology studies. PMID:21750779

  20. Methanogenesis from sucrose by defined immobilized consortia. [Escherichia coli; Acetobacterium woodii; Desulfovibrio vulgaris; Methanosarcina barkeri; Methanobacterium formicicum

    SciTech Connect

    Jones, W.J.; Guyot, J.P.; Wolfe, R.S.

    1984-01-01

    A bacterial consortium capable of sucrose degradation primarily to CH/sub 4/ and CO/sub 2/ was constructed, with acetate as the key methanogenic precursor. In addition, the effect of agar immobilization on the activity of the consortium was determined. The primary fermentative organism, Escherichia coli, produced acetate, formate, H/sub 2/, and CO/sub 2/ (known substrates for methanogens), as well as ethanol and lactate, compounds that are not substrates for methanogens. Oxidation of the nonmethanogenic substrates, lactate and ethanol, to acetate was mediated by the addition of Acetobacterium woodii and Desulfovibrio vulgaris. The methanogenic stage was accomplished by the addition of the acetophilic methanogen Methanosarcina barkeri and the hydrogenophilic methanogen Methanobacterium formicicum. Results of studies with low substrate concentrations (0.05 to 0.2% (wt/vol)), a growth-limiting medium, and the five-component consortium indicated efficient conversion (40%) of sucrose carbon to CH/sub 4/. Significant decreases in yields of CH/sub 4/ and rates of CH/sub 4/ production were observed if any component of the consortium was omitted. Approximately 70% of the CH/sub 4/ generated occurred via acetate. Agar-immobilized cells of the consortium exhibited yields of CH/sub 4/ and rates of CH/sub 4/ production from sucrose similar to those of nonimmobilized cells. The rate of CH/sub 4/ production decreased by 25% when cysteine was omitted from reaction conditions and by 40% when the immobilized consortium was stored for 1 week at 4/sup 0/C.

  1. Methanogen Population of an Oil Production Skimmer Pit and the Effects of Environmental Factors and Substrate Availability on Methanogenesis and Corrosion Rates.

    PubMed

    Conlette, Okoro Chuma; Emmanuel, Nwezza Elebe; Chijoke, Okpokwasili Gideon

    2016-07-01

    Assessment of microbial communities from an oil production skimmer pit using 16S rRNA gene sequencing technique revealed massive dominance of methanogenic archaea in both the skimmer pit water and sediment samples. The dominant genera of methanogens involved are mostly the acetotrophic Methanosaeta (36-83 %), and the hydrogenotrophic Methanococcus (49 %) indicating that methanogenesis is the dominant terminal metabolic process in the skimmer pit. Further studies showed that the methanogens had their optimal activity at pH 6-6.5, salinity of 100 mM, and temperature of 35-45 °C. When appropriate substrates are available and utilized by methanogens, methane production correlates with general corrosion rates (r = +0.927; p < 0.01), and under different conditions of pH, salinity and temperature, methane production showed significantly strong positive correlations (r = +0.824, +0.827, and +0.805; p < 0.01, respectively) with general corrosion rates. To the best of our knowledge, this research work was the first to assess microbial community composition of an oil production skimmer pit at Escravos facility in Nigeria. PMID:27075654

  2. Development and Sensitivity Analysis of a Frost Risk model based primarily on freely distributed Earth Observation data

    NASA Astrophysics Data System (ADS)

    Louka, Panagiota; Petropoulos, George; Papanikolaou, Ioannis

    2015-04-01

    The ability to map the spatiotemporal distribution of extreme climatic conditions, such as frost, is a significant tool in successful agricultural management and decision making. Nowadays, with the development of Earth Observation (EO) technology, it is possible to obtain accurately, timely and in a cost-effective way information on the spatiotemporal distribution of frost conditions, particularly over large and otherwise inaccessible areas. The present study aimed at developing and evaluating a frost risk prediction model, exploiting primarily EO data from MODIS and ASTER sensors and ancillary ground observation data. For the evaluation of our model, a region in north-western Greece was selected as test site and a detailed sensitivity analysis was implemented. The agreement between the model predictions and the observed (remotely sensed) frost frequency obtained by MODIS sensor was evaluated thoroughly. Also, detailed comparisons of the model predictions were performed against reference frost ground observations acquired from the Greek Agricultural Insurance Organization (ELGA) over a period of 10-years (2000-2010). Overall, results evidenced the ability of the model to produce reasonably well the frost conditions, following largely explainable patterns in respect to the study site and local weather conditions characteristics. Implementation of our proposed frost risk model is based primarily on satellite imagery analysis provided nowadays globally at no cost. It is also straightforward and computationally inexpensive, requiring much less effort in comparison for example to field surveying. Finally, the method is adjustable to be potentially integrated with other high resolution data available from both commercial and non-commercial vendors. Keywords: Sensitivity analysis, frost risk mapping, GIS, remote sensing, MODIS, Greece

  3. Surgery of highly eloquent gliomas primarily assessed as non-resectable: risks and benefits in a cohort study

    PubMed Central

    2013-01-01

    Background Today, the treatment of choice for high- and low-grade gliomas requires primarily surgical resection to achieve the best survival and quality of life. Nevertheless, many gliomas within highly eloquent cortical regions, e.g., insula, rolandic, and left perisylvian cortex, still do not undergo surgery because of the impending risk of surgery-related deficits at some centers. However, pre and intraoperative brain mapping, intraoperative neuromonitoring (IOM), and awake surgery increase safety, which allows resection of most of these tumors with a considerably low rate of postoperatively new deficits. Methods Between 2006 and 2012, we resected 47 out of 51 supratentorial gliomas (92%), which were primarily evaluated to be non-resectable during previous presentation at another neurosurgical department. Out of these, 25 were glioblastomas WHO grade IV (53%), 14 were anaplastic astrocytomas WHO grade III (30%), 7 were diffuse astrocytomas WHO grade II (15%), and one was a pilocytic astrocytoma WHO grade I (2%). All data, including pre and intraoperative brain mapping and monitoring (IOM) by motor evoked potentials (MEPs) were reviewed and related to the postoperative outcome. Results Awake surgery was performed in 8 cases (17%). IOM was required in 38 cases (81%) and was stable in 18 cases (47%), whereas MEPs changed the surgical strategy in 10 cases (26%). Thereby, gross total resection was achieved in 35 cases (74%). Postoperatively, 17 of 47 patients (36%) had a new motor or language deficit, which remained permanent in 8.5% (4 patients). Progression-free follow-up was 11.3 months (range: 2 weeks – 64.5 months) and median survival was 14.8 months (range: 4 weeks – 20.5 months). Median Karnofsky Performance Scale was 85 before and 80 after surgery). Conclusions In specialized centers, most highly eloquent gliomas are eligible for surgical resection with an acceptable rate of surgery-related deficits; therefore, they should be referred to specialized

  4. Oil well pump driving unit

    SciTech Connect

    Gilbertson, T. A.

    1984-11-06

    An oil well pumping apparatus which includes a submerged reciprocating pump mounted in a tubing arrangement communicating with the wellhead, a sucker rod string extending through the tubing arrangement and connected in driving relation with the pump, and a pumping tee and stuffing box arrangement mounted on the casing of the well at the wellhead and including a sealed drive rod arrangement in the stuffing box connected in driving relation to said sucker rod string, and a pump driving unit. The pump driving unit includes a hydraulic cylinder and support means including a gimbal arrangement for supporting the hydraulic cylinder over the stuffing box with the axis of the cylinder rod aligned with the axis of said stuffing box. A coupling means is provided for coupling the cylinder rod to the sealed drive rod arrangement. A hydraulic drive/control unit is coupled to said in/out fluid line for operating cycle consisting of a hydraulic power upstroke and a gravity power downstroke. An assist cylinder and accumulator combination are provided to counteract part of the weight of the rod string and thus reduce the workload on t

  5. Driving Performance Under Alcohol in Simulated Representative Driving Tasks

    PubMed Central

    Kenntner-Mabiala, Ramona; Kaussner, Yvonne; Jagiellowicz-Kaufmann, Monika; Hoffmann, Sonja; Krüger, Hans-Peter

    2015-01-01

    Abstract Comparing drug-induced driving impairments with the effects of benchmark blood alcohol concentrations (BACs) is an approved approach to determine the clinical relevance of findings for traffic safety. The present study aimed to collect alcohol calibration data to validate findings of clinical trials that were derived from a representative test course in a dynamic driving simulator. The driving performance of 24 healthy volunteers under placebo and with 0.05% and 0.08% BACs was measured in a double-blind, randomized, crossover design. Trained investigators assessed the subjects’ driving performance and registered their driving errors. Various driving parameters that were recorded during the simulation were also analyzed. Generally, the participants performed worse on the test course (P < 0.05 for the investigators’ assessment) under the influence of alcohol. Consistent with the relevant literature, lane-keeping performance parameters were sensitive to the investigated BACs. There were significant differences between the alcohol and placebo conditions in most of the parameters analyzed. However, the total number of errors was the only parameter discriminating significantly between all three BAC conditions. In conclusion, data show that the present experimental setup is suitable for future psychopharmacological research. Thereby, for each drug to be investigated, we recommend to assess a profile of various parameters that address different levels of driving. On the basis of this performance profile, the total number of driving errors is recommended as the primary endpoint. However, this overall endpoint should be completed by a specifically sensitive parameter that is chosen depending on the effect known to be induced by the tested drug. PMID:25689289

  6. Magnetic compression laser driving circuit

    DOEpatents

    Ball, D.G.; Birx, D.; Cook, E.G.

    1993-01-05

    A magnetic compression laser driving circuit is disclosed. The magnetic compression laser driving circuit compresses voltage pulses in the range of 1.5 microseconds at 20 kilovolts of amplitude to pulses in the range of 40 nanoseconds and 60 kilovolts of amplitude. The magnetic compression laser driving circuit includes a multi-stage magnetic switch where the last stage includes a switch having at least two turns which has larger saturated inductance with less core material so that the efficiency of the circuit and hence the laser is increased.

  7. Magnetic compression laser driving circuit

    DOEpatents

    Ball, Don G.; Birx, Dan; Cook, Edward G.

    1993-01-01

    A magnetic compression laser driving circuit is disclosed. The magnetic compression laser driving circuit compresses voltage pulses in the range of 1.5 microseconds at 20 Kilovolts of amplitude to pulses in the range of 40 nanoseconds and 60 Kilovolts of amplitude. The magnetic compression laser driving circuit includes a multi-stage magnetic switch where the last stage includes a switch having at least two turns which has larger saturated inductance with less core material so that the efficiency of the circuit and hence the laser is increased.

  8. Driving Speed vs Fuel Efficiency.

    ERIC Educational Resources Information Center

    Vest, Floyd

    1980-01-01

    A mathematical treatment of the relationship between driving speed and fuel efficiency is presented. The material involves applications of exponentials, logarithms, and elementary calculus, and is intended to be enrichment material for secondary and lower college mathematics classes. (MP)

  9. Apparatus for forming drive belts

    NASA Technical Reports Server (NTRS)

    Topits, A., Jr. (Inventor)

    1974-01-01

    An apparatus for manufacturing belts, such as seamless belts, is provided, the apparatus has relatively movable rollers that are mounted in an oven. A belt blank, for example, of a thin polyester film, is rotated on the rollers as heat is applied. Four rollers, each mounted on a separate roller assembly, are movable along appropriate tracks while a fifth centrally located roller is stationary. A pair of dc motors are operatively connected to a speed reduction gear assembly to provide a pair of rotating drive shafts that extend into the oven. One rotating shaft drives all of the rollers through a rotational gear assembly while the other drive shaft is capable of positioning the movable rollers through respective rotating threaded shafts. Control devices are provided for controlling the motors while measuring devices are operatively connected to the positional drive shaft to indicate the position of the rollers.

  10. Novel driving scheme for FLCD

    NASA Astrophysics Data System (ADS)

    Wu, Jiin-chuan; Wang, Chi-Chang

    1996-03-01

    A frame change data driving scheme (FCDDS) for ferroelectric LCD(FLCD) of matrix- addressing is developed which uses only positive voltages for the row and column waveforms to achieve bipolar driving waveforms on the FLCD pixels. Thus the required supply voltage for the driver chips is half that of the conventional driving scheme. Each scan line is addressed in only twice the switching time (tau) (minimum response time of FLC) so that this scheme is suitable for high duty ratio panels. In order to meet this bistable electro-optic effect of FLCD and zero net dc voltage across each pixel of the liquid crystal, turning on and turning off pixels are done at different time slots and frame slots. This driving scheme can be easily implemented using commercially available STN LCD drivers plus a small external circuit or by making an ASIC which is a slight modification of the STN driver. Both methods are discussed.

  11. Distracted Driving Raises Crash Risk

    MedlinePlus

    ... Raises Crash Risk Video technology and in-vehicle sensors showed that distracted driving, especially among new drivers, ... whenever the cars were moving. A suite of sensors recorded acceleration, sudden braking or swerving, and other ...

  12. Dopaminergic Circuitry Underlying Mating Drive.

    PubMed

    Zhang, Stephen X; Rogulja, Dragana; Crickmore, Michael A

    2016-07-01

    We develop a new system for studying how innate drives are tuned to reflect current physiological needs and capacities, and how they affect sensory-motor processing. We demonstrate the existence of male mating drive in Drosophila, which is transiently and cumulatively reduced as reproductive capacity is depleted by copulations. Dopaminergic activity in the anterior of the superior medial protocerebrum (SMPa) is also transiently and cumulatively reduced in response to matings and serves as a functional neuronal correlate of mating drive. The dopamine signal is transmitted through the D1-like DopR2 receptor to P1 neurons, which also integrate sensory information relevant to the perception of females, and which project to courtship motor centers that initiate and maintain courtship behavior. Mating drive therefore converges with sensory information from the female at the point of transition to motor output, controlling the propensity of a sensory percept to trigger goal-directed behavior. PMID:27292538

  13. [Driving licenses and medical fitness].

    PubMed

    Sénéchal, Antoine; Manaouil, Cécile

    2015-09-01

    The Highway Code requires that any vehicle driver is constantly in a state and in position of performing easily and without delay all the maneuvers required of them. What about a vehicle driver suffering from a medical condition that does not allow it to meet the requirements of the Highway Code? While it may seem obvious that some diseases irrefutably presumed inability to drive, the regulatory authority had to answer a number of questions. What people should be subject to medical control of driving ability? What constitutes control? Who may be responsible for this control? The government, through a decree dated 17 July 2012 relating to medical control of driving ability, came to ask a new legal framework in this area meets all of these issues. In addition, a decree of 31 July 2012 came to specify the implementation rules for monitoring medical fitness to drive. PMID:25900083

  14. Dangers of Texting While Driving

    MedlinePlus

    ... laws Currently there is no national ban on texting or using a wireless phone while driving, but a number of states have passed laws banning texting or wireless phones or requiring hands-free use ...

  15. Direct drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1998-03-10

    A positive-drive field actuator motor is described which includes a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately. 62 figs.

  16. Mechanical drive for blood pump

    DOEpatents

    Bifano, N.J.; Pouchot, W.D.

    1975-07-29

    This patent relates to a highly efficient blood pump to be used as a replacement for a ventricle of the human heart to restore people disabled by heart disease. The mechanical drive of the present invention is designed to operate in conjunction with a thermoelectric converter power source. The mechanical drive system essentially converts the output of a rotary power into pulsatile motion so that the power demand from the thermoelectric converter remains essentially constant while the blood pump output is pulsed. (auth)

  17. Warp drive with zero expansion

    NASA Astrophysics Data System (ADS)

    Natário, José

    2002-03-01

    It is commonly believed that Alcubierre's warp drive works by contracting space in front of the warp bubble and expanding the space behind it. We show that this contraction/expansion is but a marginal consequence of the choice made by Alcubierre and explicitly construct a similar spacetime where no contraction/expansion occurs. Global and optical properties of warp-drive spacetimes are also discussed.

  18. Direct drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1998-01-01

    A positive-drive field actuator motor including a stator carrying at least one field actuator which changes in dimension responsive to application of an energy field, and at least one drive shoe movable by the dimensional changes of the field actuator to contact and move a rotor element with respect to the stator. Various embodiments of the motor are disclosed, and the rotor element may be moved linearly or arcuately.

  19. Low backlash direct drive actuator

    DOEpatents

    Kuklo, T.C.

    1994-10-25

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw. 10 figs.

  20. Low backlash direct drive actuator

    DOEpatents

    Kuklo, Thomas C.

    1994-01-01

    A low backlash direct drive actuator is described which comprises a motor such as a stepper motor having at least 200 steps per revolution; a two part hub assembly comprising a drive hub coaxially attached to the shaft of the motor and having a plurality of drive pins; a driven hub having a plurality of bores in one end thereof in alignment with the drive pins in the drive hub and a threaded shaft coaxially mounted in an opposite end of the driven hub; and a housing having a central bore therein into which are fitted the drive hub and driven hub, the housing having a motor mount on one end thereof to which is mounted the stepper motor, and a closed end portion with a threaded opening therein coaxial with the central bore in the housing and receiving therein the threaded shaft attached to the driven hub. Limit switches mounted to the housing cooperate with an enlarged lip on the driven hub to limit the lateral travel of the driven hub in the housing, which also acts to limit the lateral travel of the threaded shaft which functions as a lead screw.

  1. [Driving license and mellitus diabetes].

    PubMed

    Cimino, Luc; Deneufgermain, Alain; Lalau, Jean-Daniel

    2015-10-01

    For the "light group" as for the "heavy group" driving license cannot be issued or renewed to the applicant or drivers suffering from a condition that may constitute or lead to functional disability jeopardize road safety when driving a motor vehicle. The decision to issue or renew the license by the prefectural authority is taken on the advice of the departmental medical commission or a licensed physician. The decree of August 31, 2010 establishes the list of medical conditions incompatible with obtaining or maintaining the driving license or which may give rise to the issue of driving license limited validity. "Diabetes mellitus treated with medications that can cause hypoglycemia" belongs to this list. If the medical control of driving ability comes at the initiative of the user, the treating physician should firstly ensure the understanding of prescribed treatments that can cause hypoglycaemic episodes and other by informing diabetic person she must pass a medical examination of fitness to drive in a licensed physician. PMID:25956301

  2. Adolescent Pornography Use and Dating Violence among a Sample of Primarily Black and Hispanic, Urban-Residing, Underage Youth

    PubMed Central

    Rothman, Emily F.; Adhia, Avanti

    2015-01-01

    This cross-sectional study was designed to characterize the pornography viewing preferences of a sample of U.S.-based, urban-residing, economically disadvantaged, primarily Black and Hispanic youth (n = 72), and to assess whether pornography use was associated with experiences of adolescent dating abuse (ADA) victimization. The sample was recruited from a large, urban, safety net hospital, and participants were 53% female, 59% Black, 19% Hispanic, 14% Other race, 6% White, and 1% Native American. All were 16–17 years old. More than half (51%) had been asked to watch pornography together by a dating or sexual partner, and 44% had been asked to do something sexual that a partner saw in pornography. Adolescent dating abuse (ADA) victimization was associated with more frequent pornography use, viewing pornography in the company of others, being asked to perform a sexual act that a partner first saw in pornography, and watching pornography during or after marijuana use. Approximately 50% of ADA victims and 32% of non-victims reported that they had been asked to do a sexual act that their partner saw in pornography (p = 0.15), and 58% did not feel happy to have been asked. Results suggest that weekly pornography use among underage, urban-residing youth may be common, and may be associated with ADA victimization. PMID:26703744

  3. Human land uses enhance sediment denitrification and N2O production in Yangtze lakes primarily by influencing lake water quality

    NASA Astrophysics Data System (ADS)

    Liu, W.; Yao, L.; Wang, Z.; Xiong, Z.; Liu, G.

    2015-10-01

    Sediment denitrification in lakes alleviates the effects of eutrophication through the removal of nitrogen to the atmosphere as N2O and N2. However, N2O contributes notably to the greenhouse effect and global warming. Human land uses (e.g. agricultural and urban areas) strongly affect lake water quality and sediment characteristics, which, in turn, may regulate lake sediment denitrification and N2O production. In this study, we investigated sediment denitrification and N2O production and their relationships to within-lake variables and watershed land uses in 20 lakes from the Yangtze River basin in China. The results indicated that both lake water quality and sediment characteristics were significantly influenced by watershed land uses. N2O production rates increased with increasing background denitrification rates. Background denitrification and N2O production rates were positively related to water nitrogen concentrations but were not significantly correlated with sediment characteristics and plant community structure. A significant positive relationship was observed between background denitrification rate and percentage of human-dominated land uses (HDL) in watersheds. Structural equation modelling revealed that the indirect effects of HDL on sediment denitrification and N2O production in Yangtze lakes were mediated primarily through lake water quality. Our findings also suggest that although sediments in Yangtze lakes can remove large quantities of nitrogen through denitrification, they may also be an important source of N2O, especially in lakes with high nitrogen content.

  4. Adolescent Pornography Use and Dating Violence among a Sample of Primarily Black and Hispanic, Urban-Residing, Underage Youth.

    PubMed

    Rothman, Emily F; Adhia, Avanti

    2015-01-01

    This cross-sectional study was designed to characterize the pornography viewing preferences of a sample of U.S.-based, urban-residing, economically disadvantaged, primarily Black and Hispanic youth (n = 72), and to assess whether pornography use was associated with experiences of adolescent dating abuse (ADA) victimization. The sample was recruited from a large, urban, safety net hospital, and participants were 53% female, 59% Black, 19% Hispanic, 14% Other race, 6% White, and 1% Native American. All were 16-17 years old. More than half (51%) had been asked to watch pornography together by a dating or sexual partner, and 44% had been asked to do something sexual that a partner saw in pornography. Adolescent dating abuse (ADA) victimization was associated with more frequent pornography use, viewing pornography in the company of others, being asked to perform a sexual act that a partner first saw in pornography, and watching pornography during or after marijuana use. Approximately 50% of ADA victims and 32% of non-victims reported that they had been asked to do a sexual act that their partner saw in pornography (p = 0.15), and 58% did not feel happy to have been asked. Results suggest that weekly pornography use among underage, urban-residing youth may be common, and may be associated with ADA victimization. PMID:26703744

  5. Bimanual cross-talk during reaching movements is primarily related to response selection, not the specification of motor parameters

    NASA Technical Reports Server (NTRS)

    Hazeltine, Eliot; Diedrichsen, Joern; Kennerley, Steven W.; Ivry, Richard B.

    2003-01-01

    Simultaneous reaching movements made with the two hands can show a considerable increase in reaction time (RT) when they differ in terms of direction or extent, compared to when the movements involve the same direction and extent. This cost has been attributed to cross-talk in the specification of the motor parameters for the two hands. However, a recent study [Diedrichsen, Hazeltine, Kennerley, & Ivry, (2001). Psychological Science, 12, 493-498] indicates that when reaching movements are cued by the onset of the target endpoint, no compatibility effects are observed. To determine why directly cued movements are immune from interference, we varied the stimulus onset asynchrony for the two movements and used different combinations of directly cued and symbolically cued movements. In two experiments, compatibility effects were only observed when both movements were symbolically cued. No difference was found between compatible and incompatible movements when both movements were directly cued or when one was directly cued and the other was symbolically cued. These results indicate that interference is not related to the specification of movement parameters but instead emerges from processes associated with response selection. Moreover, the data suggest that cross-talk, when present, primarily shortens the RT of the second movement on compatible trials rather than lengthening this RT on incompatible trials.

  6. Effect of thyroid peroxidase antibodies on thyroid-stimulating hormone reference limits in a primarily Latina population

    PubMed Central

    Lee, Richard H; Spencer, Carole A; Montoro, Martin N; Aghajanian, Paola; Goodwin, T Murphy; Miller, Erin A; Petrovic, Ivana; Braverman, Lewis E; Mestman, Jorge H

    2009-01-01

    The aim of the paper is to determine the prevalence of thyroid peroxidase antibodies (TPOAb) and assess its effect on the thyroid-stimulating hormone (TSH) reference range during pregnancy in a primarily Latina population. Serum samples were collected from healthy pregnant women and non-pregnant controls. TSH reference ranges were calculated when TPOAb-positive patients were either included or excluded. A total of 134 pregnant women and 107 non-pregnant controls were recruited. Positive TPOAb titres were found in 23 (17.2%) of the 134 pregnant women, and in 14 (13.1%) of the 107 non-pregnant controls. When the TPOAb-positive women were included in the TSH analysis, the upper reference limit using two different methods was consistently higher: 0–2.2 fold in the non-pregnant women, 2.01–2.78 fold in the first trimester, 3.18–4.7 fold in the second and 1.05–1.42 fold in the third. The lower TSH reference limit was not affected by the inclusion of TPOAb-positive subjects. In conclusion, inclusion of TPOAb-positive patients results in higher upper reference limits during pregnancy.

  7. Identification of gunshots to the head by detection of RNA in backspatter primarily expressed in brain tissue.

    PubMed

    Lux, Constantin; Schyma, Christian; Madea, Burkhard; Courts, Cornelius

    2014-04-01

    Traces of backspatter recovered from the inside of the barrel of a gun that was used to deliver suicidal or homicidal contact shots may be a source of valuable forensic evidence and first systematic investigations of the persistence of victim DNA from inside firearms have been presented. The aim of the present study was to include victim RNA in such analyses to determine the origin of tissues in addition and parallel to standard DNA profiling for forensic identification purposes. In a first step, suitable mRNA (C1orf61) and micro-RNAs (miR-124a and miR-124*) that are primarily expressed in brain tissue were selected from potential candidates and confirmed using quantitative PCR (qPCR). Secondly, a co-extraction procedure for RNA and DNA was established and brain differentiability of the selected RNAs was demonstrated via qPCR using samples from experimental shots at ballistic models. In a third step, this procedure was successfully applied to analyse samples from real casework comprising eight cases of suicidal contact shots. In this pilot study, we are first to report the possibility of co-extracting mRNA, miRNA and DNA from ballistic trace samples collected from the inside of firearms and we demonstrate that RNA and DNA based analyses can be performed in parallel to produce informative and highly complementary evidence. PMID:24598119

  8. Predictors of moderated drinking in a primarily alcohol dependent sample of men who have sex with men

    PubMed Central

    Kuerbis, Alexis; Morgenstern, Jon; Hail, Lisa

    2012-01-01

    Understanding for whom moderated drinking is a viable, achievable, and sustainable goal among those with a range of alcohol use disorders (AUD) remains an important public health question. Despite common acceptance as severe risk factors, there is little empirical evidence to conclude whether co-occurring mental health disorders or drug dependence contribute to an individual’s inability to successfully moderate his drinking. Utilizing secondary data analysis, the purpose of this study was to identify predictors of moderation among both treatment seeking and non-treatment seeking, primarily alcohol dependent, problem drinking men who have sex with men (MSM), with an emphasis on the high risk factors psychiatric comorbidity and drug dependence. Problem drinkers (N=187) were assessed, provided feedback about their drinking, given the option to receive brief AUD treatment or change their drinking on their own, and then followed for 15 months. Findings revealed that neither psychiatric comorbidity or drug dependence predicted ability to achieve moderation when controlling for alcohol dependence severity. Those who were younger, more highly educated, and had more mild alcohol dependence were more likely to achieve moderated drinking. Impact of treatment on predictors is explored. Limitations of this study and arenas for future research are discussed. PMID:22201219

  9. Antigen Specificity of γδ T Cells Depends Primarily on the Flanking Sequences of CDR3δ*

    PubMed Central

    Xi, Xueyan; Guo, Yang; Chen, Hui; Xu, Chunping; Zhang, Huiyuan; Hu, Hongbo; Cui, Lianxian; Ba, Denian; He, Wei

    2009-01-01

    The structural basis that determines the specificity of γδ T cell receptor (TCR) recognition remains undefined. Our previous data show that the complementary determining region of human TCRδ (CDR3δ) is critical to ligand binding. Here we used linear and configurational approaches to examine the roles of V, N-D-N, or J regions in CDR3δ-mediated antigen recognition. Surprisingly, we found that the binding activities of CDR3δ from different γδ TCRs to their target tissues and ligands depend on the conserved flanking sequences (V and J) but not as much on the D region of CDR3δ fragment. We further defined the key residues in the V and J regions of CDR3δ fragments, including the cysteine residue in the V fragment and the leucine residue in the J fragment that determine their ligand binding specificity. Our results demonstrate that TCRδ primarily uses conserved flanking regions to bind ligands. This finding may provide an explanation for the limited number of γδ TCR ligands that have as yet been identified. PMID:19666468

  10. Affinity Maturation of a Potent Family of HIV Antibodies Is Primarily Focused on Accommodating or Avoiding Glycans.

    PubMed

    Garces, Fernando; Lee, Jeong Hyun; de Val, Natalia; de la Pena, Alba Torrents; Kong, Leopold; Puchades, Cristina; Hua, Yuanzi; Stanfield, Robyn L; Burton, Dennis R; Moore, John P; Sanders, Rogier W; Ward, Andrew B; Wilson, Ian A

    2015-12-15

    The high-mannose patch on the HIV-1 envelope (Env) glycoprotein is the epicenter for binding of the potent broadly neutralizing PGT121 family of antibodies, but strategies for generating such antibodies by vaccination have not been defined. We generated structures of inferred antibody intermediates by X-ray crystallography and electron microscopy to elucidate the molecular events that occurred during evolution of this family. Binding analyses revealed that affinity maturation was primarily focused on avoiding, accommodating, or binding the N137 glycan. The overall antibody approach angle to Env was defined very early in the maturation process, yet some variation evolved in the PGT121 family branches that led to differences in glycan specificities in their respective epitopes. Furthermore, we determined a crystal structure of the recombinant BG505 SOSIP.664 HIV-1 trimer with a PGT121 family member at 3.0 Å that, in concert with these antibody intermediate structures, provides insights to advance design of HIV vaccine candidates. PMID:26682982

  11. The Reliability and Validity of Drug Users' Self Reports of Amphetamine Use Among Primarily Heroin and Cocaine Users

    PubMed Central

    Napper, Lucy E.; Fisher, Dennis G.; Johnson, Mark E.; Wood, Michele M.

    2009-01-01

    Relatively few studies have addressed the psychometric properties of self-report measures of amphetamine use. This study examines the reliability and validity of the Risk Behavior Assessment's (RBA) lifetime and recent amphetamine-use questions. To evaluate validity, 4027 out-of-treatment primarily cocaine and heroin users provided urine samples that were compared to self-report data; to evaluate reliability, 218 completed the RBA at two time points, 48 hours apart. In the overall sample, self-reports demonstrated moderately high validity, with a 95% accuracy rate (kappa =.54). When analysis was restricted to recent amphetamine users validity was slightly lower (71.5% accuracy; kappa = .41). Test-retest data indicated good reliability for self-reports of ever having used amphetamine (kappa =.79), and amphetamine use in the past 30 days (.75 < r < .91). Out-of-treatment drug users provided accurate self-reports of amphetamine use. Reliable and valid measures are essential for describing and predicting trends in amphetamine use, evaluating the effectiveness of interventions, and developing policies and programs. PMID:20053503

  12. China Continues to Drive Foreign-Student Growth in the United States

    ERIC Educational Resources Information Center

    McMurtrie, Beth

    2012-01-01

    This article discusses the results of the latest "Open Doors" report from the Institute of International Education. The report states that thousands of mainland Chinese students in pursuit of an American education helped drive up international enrollments at colleges across the United States. Double-digit growth from China, primarily at the…

  13. Vascular Endothelial Growth Factor Acts Primarily via Platelet-Derived Growth Factor Receptor α to Promote Proliferative Vitreoretinopathy

    PubMed Central

    Pennock, Steven; Haddock, Luis J.; Mukai, Shizuo; Kazlauskas, Andrius

    2015-01-01

    Proliferative vitreoretinopathy (PVR) is a nonneovascular blinding disease and the leading cause for failure in surgical repair of rhegmatogenous retinal detachments. Once formed, PVR is difficult to treat. Hence, there is an acute interest in developing approaches to prevent PVR. Of the many growth factors and cytokines that accumulate in vitreous as PVR develops, neutralizing vascular endothelial growth factor (VEGF) A has recently been found to prevent PVR in at least one animal model. The goal of this study was to test if Food and Drug Administration–approved agents could protect the eye from PVR in multiple animal models and to further investigate the underlying mechanisms. Neutralizing VEGF with aflibercept (VEGF Trap-Eye) safely and effectively protected rabbits from PVR in multiple models of disease. Furthermore, aflibercept reduced the bioactivity of both experimental and clinical PVR vitreous. Finally, although VEGF could promote some PVR-associated cellular responses via VEGF receptors expressed on the retinal pigment epithelial cells that drive this disease, VEGF's major contribution to vitreal bioactivity occurred via platelet-derived growth factor receptor α. Thus, VEGF promotes PVR by a noncanonical ability to engage platelet-derived growth factor receptor α. These findings indicate that VEGF contributes to nonangiogenic diseases and that anti–VEGF-based therapies may be effective on a wider spectrum of diseases than previously appreciated. PMID:25261788

  14. Half-century evidence from western Canada shows forest dynamics are primarily driven by competition followed by climate

    PubMed Central

    Zhang, Jian; Huang, Shongming; He, Fangliang

    2015-01-01

    Tree mortality, growth, and recruitment are essential components of forest dynamics and resiliency, for which there is great concern as climate change progresses at high latitudes. Tree mortality has been observed to increase over the past decades in many regions, but the causes of this increase are not well understood, and we know even less about long-term changes in growth and recruitment rates. Using a dataset of long-term (1958–2009) observations on 1,680 permanent sample plots from undisturbed natural forests in western Canada, we found that tree demographic rates have changed markedly over the last five decades. We observed a widespread, significant increase in tree mortality, a significant decrease in tree growth, and a similar but weaker trend of decreasing recruitment. However, these changes varied widely across tree size, forest age, ecozones, and species. We found that competition was the primary factor causing the long-term changes in tree mortality, growth, and recruitment. Regional climate had a weaker yet still significant effect on tree mortality, but little effect on tree growth and recruitment. This finding suggests that internal community-level processes—more so than external climatic factors—are driving forest dynamics. PMID:25775576

  15. Half-century evidence from western Canada shows forest dynamics are primarily driven by competition followed by climate.

    PubMed

    Zhang, Jian; Huang, Shongming; He, Fangliang

    2015-03-31

    Tree mortality, growth, and recruitment are essential components of forest dynamics and resiliency, for which there is great concern as climate change progresses at high latitudes. Tree mortality has been observed to increase over the past decades in many regions, but the causes of this increase are not well understood, and we know even less about long-term changes in growth and recruitment rates. Using a dataset of long-term (1958-2009) observations on 1,680 permanent sample plots from undisturbed natural forests in western Canada, we found that tree demographic rates have changed markedly over the last five decades. We observed a widespread, significant increase in tree mortality, a significant decrease in tree growth, and a similar but weaker trend of decreasing recruitment. However, these changes varied widely across tree size, forest age, ecozones, and species. We found that competition was the primary factor causing the long-term changes in tree mortality, growth, and recruitment. Regional climate had a weaker yet still significant effect on tree mortality, but little effect on tree growth and recruitment. This finding suggests that internal community-level processes-more so than external climatic factors-are driving forest dynamics. PMID:25775576

  16. Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique

    PubMed Central

    2015-01-01

    Efficient driving of piezoelectric materials is desirable when operating transducers for biomedical applications such as high intensity focused ultrasound (HIFU) or ultrasound imaging. More efficient operation reduces the electric power required to produce the desired bioeffect or contrast. Our preliminary work [Cole et al. Journal of Physics: Condensed Matter. 2014;26(13):135901.] suggested that driving transducers by applying orthogonal electric fields can significantly reduce the coercivity that opposes ferroelectric switching. We present here the experimental validation of this biaxial driving technique using piezoelectric ceramics typically used in HIFU. A set of narrow-band transducers was fabricated with two sets of electrodes placed in an orthogonal configuration (following the propagation and the lateral mode). The geometry of the ceramic was chosen to have a resonance frequency similar for the propagation and the lateral mode. The average (± s.d.) resonance frequency of the samples was 465.1 (± 1.5) kHz. Experiments were conducted in which each pair of electrodes was driven independently and measurements of effective acoustic power were obtained using the radiation force method. The efficiency (acoustic/electric power) of the biaxial driving method was compared to the results obtained when driving the ceramic using electrodes placed only in the pole direction. Our results indicate that the biaxial method increases efficiency from 50% to 125% relative to the using a single electric field. PMID:26418550

  17. Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique.

    PubMed

    Pichardo, Samuel; Silva, Rafael R C; Rubel, Oleg; Curiel, Laura

    2015-01-01

    Efficient driving of piezoelectric materials is desirable when operating transducers for biomedical applications such as high intensity focused ultrasound (HIFU) or ultrasound imaging. More efficient operation reduces the electric power required to produce the desired bioeffect or contrast. Our preliminary work [Cole et al. Journal of Physics: Condensed Matter. 2014;26(13):135901.] suggested that driving transducers by applying orthogonal electric fields can significantly reduce the coercivity that opposes ferroelectric switching. We present here the experimental validation of this biaxial driving technique using piezoelectric ceramics typically used in HIFU. A set of narrow-band transducers was fabricated with two sets of electrodes placed in an orthogonal configuration (following the propagation and the lateral mode). The geometry of the ceramic was chosen to have a resonance frequency similar for the propagation and the lateral mode. The average (± s.d.) resonance frequency of the samples was 465.1 (± 1.5) kHz. Experiments were conducted in which each pair of electrodes was driven independently and measurements of effective acoustic power were obtained using the radiation force method. The efficiency (acoustic/electric power) of the biaxial driving method was compared to the results obtained when driving the ceramic using electrodes placed only in the pole direction. Our results indicate that the biaxial method increases efficiency from 50% to 125% relative to the using a single electric field. PMID:26418550

  18. Heat Shock Protein 96 is Elevated in Rheumatoid Arthritis and Activates Macrophages primarily via TLR2 Signaling

    PubMed Central

    Huang, Qi-Quan; Sobkoviak, Rudina; Jockheck-Clark, Angela; Shi, Bo; Mandelin, Arthur M.; Tak, Paul Peter; Haines, G Kennith; Nicchitta, Christopher V.; Pope, Richard M.

    2010-01-01

    Macrophages are important mediators of chronic inflammation and are prominent in the synovial lining and sublining of patients with rheumatoid arthritis (RA). Recently, we demonstrated increased toll like receptor (TLR) 2 and 4 expression and increased response to microbial TLR2 and TLR4 ligands in macrophages from the joints of RA. The current study characterized the expression of the 96-kDa heat shock glycoprotein (gp96) in the joints of RA and its role as an endogenous TLR ligand to promote innate immunity in RA. Gp96 was increased in RA compared with osteoarthritis and arthritis-free control synovial tissues. The expression of gp96 strongly correlated with inflammation and synovial lining thickness. Gp96 was increased in synovial fluid from the joints of RA compared with disease controls. Recombinant gp96 was a potent activator of macrophages, and the activation was mediated primarily through TLR2 signaling. The cellular response to gp96 was significantly stronger with RA synovial macrophages compared to peripheral blood monocytes from RA or healthy controls. The transcription of TLR2, TNFα and IL-8, but not TLR4, was significantly induced by gp96, and the induction was significantly greater in purified RA synovial macrophages. The expression of TLR2, but not TLR4, on synovial fluid macrophages strongly correlated with the level of gp96 in the synovial fluid. The present study documents the potential role of gp96 as an endogenous TLR2 ligand in RA and provides insight into the mechanism by which gp96 promotes the chronic inflammation of RA, identifying gp96 as a potential new therapeutic target. PMID:19342676

  19. Both cell substratum regulation and hormonal regulation of milk protein gene expression are exerted primarily at the posttranscriptional level

    SciTech Connect

    Eisenstein, R.S.; Rosen, J.M.

    1988-08-01

    The mechanism by which individual peptide and steroid hormones and cell-substratum interactions regulate milk protein gene expression has been studied in the COMMA-D mammary epithelial cell line. In the presence of insulin, hydrocortisone, and prolactin, growth of COMMA-D cells on floating collagen gels in comparison with that on a plastic substratum resulted in a 2.5- to 3-fold increase in the relative rate of ..beta..-casein gene transcription but a 37-fold increase in ..beta..-casein mRNA accumulation. In contrast, whey acidic protein gene transcription was constitutive in COMMA-D cells grown on either substratum, but its mRNA was unstable and little intact mature mRNA was detected. Culturing COMMA-D cells on collagen also promoted increased expression of other genes expressed in differentiated mammary epithelial cells, including those encoding ..cap alpha..- and ..gamma..-casein, transferrin, malic enzyme, and phosphoenolpyruvate carboxykinase but decreased the expression of actin and histone genes. Using COMMA-D cells, the authors defined further the role of individual hormones in influencing ..beta..-casein gene transcription. With insulin alone, a basal level of ..beta..-casein gene transcription was detected in COMMA-D cells grown on floating collagen gels. Addition of prolactin but not hydrocortisone resulted in a 2.5- to 3.0-fold increase in ..beta..-casein gene transcription, but both hormones were required to elicit the maximal 73-fold induction in mRNA accumulation. The posttranscriptional effect of hormones on casein mRNA accummulation preceded any detectable changes in the relative rate of transcription. Thus, regulation by both hormones and cell substratum of casein gene expression is exerted primarily at the post transcriptional level.

  20. Y-chromosomal diversity in Europe is clinal and influenced primarily by geography, rather than by language.

    PubMed

    Rosser, Z H; Zerjal, T; Hurles, M E; Adojaan, M; Alavantic, D; Amorim, A; Amos, W; Armenteros, M; Arroyo, E; Barbujani, G; Beckman, G; Beckman, L; Bertranpetit, J; Bosch, E; Bradley, D G; Brede, G; Cooper, G; Côrte-Real, H B; de Knijff, P; Decorte, R; Dubrova, Y E; Evgrafov, O; Gilissen, A; Glisic, S; Gölge, M; Hill, E W; Jeziorowska, A; Kalaydjieva, L; Kayser, M; Kivisild, T; Kravchenko, S A; Krumina, A; Kucinskas, V; Lavinha, J; Livshits, L A; Malaspina, P; Maria, S; McElreavey, K; Meitinger, T A; Mikelsaar, A V; Mitchell, R J; Nafa, K; Nicholson, J; Nørby, S; Pandya, A; Parik, J; Patsalis, P C; Pereira, L; Peterlin, B; Pielberg, G; Prata, M J; Previderé, C; Roewer, L; Rootsi, S; Rubinsztein, D C; Saillard, J; Santos, F R; Stefanescu, G; Sykes, B C; Tolun, A; Villems, R; Tyler-Smith, C; Jobling, M A

    2000-12-01

    Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift. PMID:11078479

  1. Initial Molecular-Level Response to Artificial Selection for Increased Aerobic Metabolism Occurs Primarily through Changes in Gene Expression.

    PubMed

    Konczal, Mateusz; Babik, Wiesław; Radwan, Jacek; Sadowska, Edyta T; Koteja, Paweł

    2015-06-01

    Experimental evolution combined with genome or transcriptome resequencing (Evolve and Resequence) represents a promising approach for advancing our understanding of the genetic basis of adaptation. Here, we applied this strategy to investigate the effect of selection on a complex trait in lines derived from a natural population of a small mammal. We analyzed the liver and heart transcriptomes of bank voles (Myodes [=Clethrionomys] glareolus) that had been selected for increased aerobic metabolism. The organs were sampled from 13th generation voles; at that point, the voles from four replicate selected lines had 48% higher maximum rates of oxygen consumption than those from four control lines. At the molecular level, the response to selection was primarily observed in gene expression: Over 300 genes were found to be differentially expressed between the selected and control lines and the transcriptome-wide pattern of expression distinguished selected lines from controls. No evidence for selection-driven changes of allele frequencies at coding sites was found: No single nucleotide polymorphism (SNP) changed frequency more than expected under drift alone and frequency changes aggregated over all SNPs did not separate selected and control lines. Nevertheless, among genes which showed highest differentiation in allele frequencies between selected and control lines we identified, using information about gene functions and the biology of the selected phenotype, plausible targets of selection; these genes, together with those identified in expression analysis, have been prioritized for further studies. Because our selection lines were derived from a natural population, the amount and the spectrum of variation available for selection probably closely approximated that typically found in populations of small mammals. Therefore, our results are relevant to the understanding of the molecular basis of complex adaptations occurring in natural vertebrate populations. PMID:25739734

  2. Organ-Specific Stability of Two Lemna rbcS mRNAs Is Determined Primarily in the Nuclear Compartment.

    PubMed Central

    Peters, J. L.; Silverthorne, J.

    1995-01-01

    It has previously been shown that the organ-specific expression of two members of the ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit (rbcS) gene family is post-transcriptionally regulated in Lemna gibba. While both small subunit genes encoding SSU1 and SSU5B were transcribed at comparable levels in root and frond nuclei, SSU1 mRNA accumulated to high levels in both roots and fronds in contrast to SSU5B mRNA, which was of very low abundance in the roots compared with the fronds. In this study, we have used two approaches to pinpoint the step(s) at which SSU1 and SSU5B mRNAs are differentially accumulated in these organs. In the first approach, total nuclear steady state mRNA was isolated from roots and fronds, and the amount of each transcript was measured by RNase protection assays and compared with the transcription rates in isolated nuclei. In the second approach, cordycepin was used to inhibit mRNA synthesis in Lemna fronds or roots, and the rate of decay of each mRNA was measured by RNA gel blot analysis or RNase protection assays. Our findings indicate that the differential accumulation of SSU1 and SSU5B mRNAs in the fronds versus the roots is determined primarily in the nuclear compartment. In addition, SSU1 was found to have a longer half-life in total steady state mRNA than SSU5B had in both organs. This feature probably accounts for SSU1 being the predominantly expressed family member. PMID:12242353

  3. Forty-four years’ experience (1963–2006) in the management of primarily infected hydatid cyst of the liver

    PubMed Central

    Prousalidis, J.; Anthimidis, G.; Fachantidis, E.; Harlaftis, N.; Aletras, H.

    2008-01-01

    Background and aim. The aim of this study was to report our 44-year experience (1963–2006) in the management of primarily infected hydatid cyst of the liver. This is a retrospective review of demographic data, clinical presentation, diagnostic work-up, surgical management, and long-term outcome of patients treated at our center. Material and methods. There were 77 patients with operated infected liver cysts. In the same period, a total of 460 cases with liver hydatidosis were treated surgically. Of those with suppurated cysts, 27 were men and 50 were women, with a mean age 54.5 years. Results. Clinical manifestations of an abscess were identified in 75% of the patients. In the earlier cases of the study, the diagnosis was made from the clinical picture, laboratory studies, in combination with plain X-ray, hepatic scintigraphy, and in the later cases with US (ultrasonography), CT (computed tomography) or MRI (magnetic resonance imaging), and ERCP (endoscopic cholangiopangreatography). Abdominal and, rarely, thoracic and abdominal or thoracoabdominal incisions were used. Total cystopericystectomy in 8 patients and partial pericystectomy and proper drainage with one or two drainage tubes of the cystic cavity in the other 69 patients were carried out. Hospital stay was between 13 and 146 days with 5 re-operations. Two patients with grossly suppurated cysts and coexistent medical problems died. The disease recurred in five patients. Conclusions. We conclude that, under good perioperative antibiotic and metabolic coverage, the infected hydatid cysts have to be completely evacuated and properly drained. The application of “conservative” surgical procedures should be preferred. Further studies are needed to solve the clinical and therapeutic problems of this serious complication. PMID:18695754

  4. Y-Chromosomal Diversity in Europe Is Clinal and Influenced Primarily by Geography, Rather than by Language

    PubMed Central

    Rosser, Zoë H.; Zerjal, Tatiana; Hurles, Matthew E.; Adojaan, Maarja; Alavantic, Dragan; Amorim, António; Amos, William; Armenteros, Manuel; Arroyo, Eduardo; Barbujani, Guido; Beckman, Gunhild; Beckman, Lars; Bertranpetit, Jaume; Bosch, Elena; Bradley, Daniel G.; Brede, Gaute; Cooper, Gillian; Côrte-Real, Helena B. S. M.; de Knijff, Peter; Decorte, Ronny; Dubrova, Yuri E.; Evgrafov, Oleg; Gilissen, Anja; Glisic, Sanja; Gölge, Mukaddes; Hill, Emmeline W.; Jeziorowska, Anna; Kalaydjieva, Luba; Kayser, Manfred; Kivisild, Toomas; Kravchenko, Sergey A.; Krumina, Astrida; Kučinskas, Vaidutis; Lavinha, João; Livshits, Ludmila A.; Malaspina, Patrizia; Maria, Syrrou; McElreavey, Ken; Meitinger, Thomas A.; Mikelsaar, Aavo-Valdur; Mitchell, R. John; Nafa, Khedoudja; Nicholson, Jayne; Nørby, Søren; Pandya, Arpita; Parik, Jüri; Patsalis, Philippos C.; Pereira, Luísa; Peterlin, Borut; Pielberg, Gerli; Prata, Maria João; Previderé, Carlo; Roewer, Lutz; Rootsi, Siiri; Rubinsztein, D. C.; Saillard, Juliette; Santos, Fabrício R.; Stefanescu, Gheorghe; Sykes, Bryan C.; Tolun, Aslihan; Villems, Richard; Tyler-Smith, Chris; Jobling, Mark A.

    2000-01-01

    Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift. PMID:11078479

  5. Maize Centromere Structure and Evolution: Sequence Analysis of Centromeres 2 and 5 Reveals Dynamic Loci Shaped Primarily by Retrotransposons

    PubMed Central

    Albert, Patrice S.; Koo, Dal-Hoe; Shi, Jinghua; Gao, Zhi; Han, Fangpu; Lee, Hyeran; Xu, Ronghui; Allison, Jamie; Birchler, James A.; Jiang, Jiming; Dawe, R. Kelly; Presting, Gernot G.

    2009-01-01

    We describe a comprehensive and general approach for mapping centromeres and present a detailed characterization of two maize centromeres. Centromeres are difficult to map and analyze because they consist primarily of repetitive DNA sequences, which in maize are the tandem satellite repeat CentC and interspersed centromeric retrotransposons of maize (CRM). Centromeres are defined epigenetically by the centromeric histone H3 variant, CENH3. Using novel markers derived from centromere repeats, we have mapped all ten centromeres onto the physical and genetic maps of maize. We were able to completely traverse centromeres 2 and 5, confirm physical maps by fluorescence in situ hybridization (FISH), and delineate their functional regions by chromatin immunoprecipitation (ChIP) with anti-CENH3 antibody followed by pyrosequencing. These two centromeres differ substantially in size, apparent CENH3 density, and arrangement of centromeric repeats; and they are larger than the rice centromeres characterized to date. Furthermore, centromere 5 consists of two distinct CENH3 domains that are separated by several megabases. Succession of centromere repeat classes is evidenced by the fact that elements belonging to the recently active recombinant subgroups of CRM1 colonize the present day centromeres, while elements of the ancestral subgroups are also found in the flanking regions. Using abundant CRM and non-CRM retrotransposons that inserted in and near these two centromeres to create a historical record of centromere location, we show that maize centromeres are fluid genomic regions whose borders are heavily influenced by the interplay of retrotransposons and epigenetic marks. Furthermore, we propose that CRMs may be involved in removal of centromeric DNA (specifically CentC), invasion of centromeres by non-CRM retrotransposons, and local repositioning of the CENH3. PMID:19956743

  6. Driving performance and driver discomfort in an elevated and standard driving position during a driving simulation.

    PubMed

    Smith, Jordan; Mansfield, Neil; Gyi, Diane; Pagett, Mark; Bateman, Bob

    2015-07-01

    The primary purposes of a vehicle driver's seat, is to allow them to complete the driving task comfortably and safely. Within each class of vehicle (e.g. passenger, commercial, industrial, agricultural), there is an expected driving position to which a vehicle cabin is designed. This paper reports a study that compares two driving positions, in relation to Light Commercial Vehicles (LCVs), in terms of driver performance and driver discomfort. In the 'elevated' driving position, the seat is higher than usually used in road vehicles; this is compared to a standard driving position replicating the layout for a commercially available vehicle. It is shown that for a sample of 12 drivers, the elevated position did not, in general, show more discomfort than the standard position over a 60 min driving simulation, although discomfort increased with duration. There were no adverse effects shown for emergency stop reaction time or for driver headway for the elevated posture compared to the standard posture. The only body part that showed greater discomfort for the elevated posture compared to the standard posture was the right ankle. A second experiment confirmed that for 12 subjects, a higher pedal stiffness eliminated the ankle discomfort problem. PMID:25766419

  7. Effect of Substrate Concentration on Carbon Isotope Fractionation during Acetoclastic Methanogenesis by Methanosarcina barkeri and M. acetivorans and in Rice Field Soil▿

    PubMed Central

    Goevert, Dennis; Conrad, Ralf

    2009-01-01

    Methanosarcina is the only acetate-consuming genus of methanogenic archaea other than Methanosaeta and thus is important in methanogenic environments for the formation of the greenhouse gases methane and carbon dioxide. However, little is known about isotopic discrimination during acetoclastic CH4 production. Therefore, we studied two species of the Methanosarcinaceae family, Methanosarcina barkeri and Methanosarcina acetivorans, and a methanogenic rice field soil amended with acetate. The values of the isotope enrichment factor (ɛ) associated with consumption of total acetate (ɛac), consumption of acetate-methyl (ɛac-methyl) and production of CH4 (ɛCH4) were an ɛac of −30.5‰, an ɛac-methyl of −25.6‰, and an ɛCH4 of −27.4‰ for M. barkeri and an ɛac of −35.3‰, an ɛac-methyl of −24.8‰, and an ɛCH4 of −23.8‰ for M. acetivorans. Terminal restriction fragment length polymorphism of archaeal 16S rRNA genes indicated that acetoclastic methanogenic populations in rice field soil were dominated by Methanosarcina spp. Isotope fractionation determined during acetoclastic methanogenesis in rice field soil resulted in an ɛac of −18.7‰, an ɛac-methyl of −16.9‰, and an ɛCH4 of −20.8‰. However, in rice field soil as well as in the pure cultures, values of ɛac and ɛac-methyl decreased as acetate concentrations decreased, eventually approaching zero. Thus, isotope fractionation of acetate carbon was apparently affected by substrate concentration. The ɛ values determined in pure cultures were consistent with those in rice field soil if the concentration of acetate was taken into account. PMID:19251888

  8. Effect of Sodium Lauryl Sulfate-Fumaric Acid Coupled Addition on the In Vitro Rumen Fermentation with Special Regard to Methanogenesis

    PubMed Central

    Abdl-Rahman, M. A.; Sawiress, F. A. R.; Abd El-Aty, A. M.

    2010-01-01

    The aim of the current study was to evaluate the effect of sodium lauryl sulfate-fumaric acid coupled addition on in vitro methangenesis and rumen fermentation. Evaluation was carried out using in vitro gas production technique. Ruminal contents were collected from five steers immediately after slaughtering and used for preparation of inoculums of mixed rumen microorganisms. Rumen fluid was then mixed with the basal diet of steers and used to generate four treatments, negative control (no additives), sodium lauryl sulfate (SLS) treated, fumaric acid treated, and SLS-fumaric acid coupled addition treated. The results revealed that, relative to control, efficiency in reduction of methanogenesis was as follows: coupled addition > SLS-addition > fumaric acid addition. Both SLS-addition and SLS-fumaric acid coupled addition demonstrated a decremental effect on ammonia nitrogen (NH3–N), total short chain volatile fatty acids (SCVFAs) concentrations and the amount of substrate degraded, and an increment effect on microbial mass and microbial yield (YATP). Nevertheless, fumaric acid did not alter any of the previously mentioned parameters but induced a decremental effect on NH3–N. Furthermore, both fumaric acid and SLS-fumaric acid coupled addition increased propionate at the expense of acetate and butyrate, while, defaunation increased acetate at the expense of propionate and butyrate. The pH value was decreased by all treatments relative to control, while, cellulase activity did not differ by different treatments. The current study can be promising strategies for suppressing ruminal methane emissions and improving ruminants feed efficiency. PMID:20445794

  9. Frontotemporal and dopaminergic control of idea generation and creative drive.

    PubMed

    Flaherty, Alice W

    2005-12-01

    This article presents a three-factor anatomical model of human idea generation and creative drive, focusing on interactions between the temporal lobes, frontal lobes, and limbic system. Evidence is drawn from functional imaging, drug studies, and lesion analysis. Temporal lobe changes, as in hypergraphia, often increase idea generation, sometimes at the expense of quality. Frontal lobe deficits may decrease idea generation, in part because of rigid judgments about an idea's worth. These phenomena are clearest in verbal creativity, and roughly parallel the pressured communication of temporal lobe epilepsy, mania, and Wernicke's aphasia-compared to the sparse speech and cognitive inflexibility of depression, Broca's aphasia, and other frontal lobe lesions. The phenomena also shape non-linguistic creativity, as in that of frontotemporal dementia. The appropriate balance between frontal and temporal activity is mediated by mutually inhibitory corticocortical interactions. Mesolimbic dopamine influences novelty seeking and creative drive. Dopamine agonists and antagonists have opposite effects on goal-directed behavior and hallucinations. Creative drive is not identical to skill-the latter depends more on neocortical association areas. However, drive correlates better with successful creative output than skill does. Traditional neuroscientific models of creativity, such as the left brain - right brain hemispheric model, emphasize skills primarily, and stress art and musical skill at the expense of language and mathematics. The three-factor model proposed here predicts findings in a broad range of normal and pathological states and can be tested in many experimental paradigms. PMID:16254989

  10. FRONTOTEMPORAL AND DOPAMINERGIC CONTROL OF IDEA GENERATION AND CREATIVE DRIVE

    PubMed Central

    Flaherty, Alice W.

    2008-01-01

    This paper presents a three-factor anatomical model of human idea generation and creative drive, focusing on interactions between the temporal lobes, frontal lobes, and limbic system. Evidence is drawn from functional imaging, drug studies, and lesion analysis. Temporal lobe changes, as in hypergraphia, often increase idea generation, sometimes at the expense of quality. Frontal lobe deficits may decrease idea generation, in part because of rigid judgments about an idea's worth. These phenomena are clearest in verbal creativity, and roughly parallel the pressured communication of temporal lobe epilepsy, mania, and Wernicke's aphasia--compared to the sparse speech and cognitive inflexibility of depression, Broca's aphasia, and other frontal lobe lesions. The phenomena also shape non-linguistic creativity, as in that of frontotemporal dementia. The appropriate balance between frontal and temporal activity is mediated by mutually inhibitory corticocortical interactions. Mesolimbic dopamine influences novelty seeking and creative drive. Dopamine agonists and antagonists have opposite effects on goal-directed behavior and hallucinations. Creative drive is not identical to skill—the latter depends more on neocortical association areas. However, drive correlates better with successful creative output than skill does. Traditional neuroscientific models of creativity, such as the left brain – right brain hemispheric model, emphasize skills primarily, and stress art and musical skill at the expense of language and mathematics. The three-factor model proposed here predicts findings in a broad range of normal and pathological states, and can be tested in many experimental paradigms. PMID:16254989

  11. Optimized Direct-Drive Uniformity

    NASA Astrophysics Data System (ADS)

    Marshall, F. J.; McKenty, P. W.; Kessler, T. J.; Forties, R.; Kelly, J. A.; Waxer, L. J.

    2002-11-01

    The means of optimizing direct-drive illumination uniformity in laser fusion implosions will be discussed. To provide the most-uniform drive, the target must be illuminated by smooth single beams, symmetrically placed on target, with the optimum beam shape. On the 60-beam OMEGA laser system these near-optimum, direct-drive illumination conditions have been achieved by smoothing each beam with 1-THz smoothing by spectral dispersion (SSD), which incorporates distributed phase plates (DPP's) and polarization smoothing (PS), and by the modified soccer-ball orientation of the beams. The current beam smoothing provides for unprecedented levels of direct-drive uniformity, approaching σ_rms ˜ 2% up to ℓ = 200 after ˜300 ps. The sensitivity of the illumination to beam shape has been studied, and a new set of DPP's have been designed and are being built to further optimize the uniformity on OMEGA. Also, the sensitivity of the drive to beam balance, beam pointing, and target positioning has been studied both by calculation and by performing target implosions allowing quantitative limits to be placed on all contributors. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC03-92SF19460.

  12. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... primarily in the business of transporting people. 37.195 Section 37.195 Transportation Office of the... transporting people. This section applies to all purchases or leases of new vehicles by private entities which are not primarily engaged in the business of transporting people, with respect to buses delivered...

  13. 49 CFR 37.103 - Purchase or lease of new non-rail vehicles by private entities primarily engaged in the business...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... private entities primarily engaged in the business of transporting people. 37.103 Section 37.103...-rail vehicles by private entities primarily engaged in the business of transporting people. (a... engaged in the business of transporting people and whose operations affect commerce, in which...

  14. 49 CFR 37.103 - Purchase or lease of new non-rail vehicles by private entities primarily engaged in the business...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... private entities primarily engaged in the business of transporting people. 37.103 Section 37.103...-rail vehicles by private entities primarily engaged in the business of transporting people. (a... engaged in the business of transporting people and whose operations affect commerce, in which...

  15. 49 CFR 37.103 - Purchase or lease of new non-rail vehicles by private entities primarily engaged in the business...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... private entities primarily engaged in the business of transporting people. 37.103 Section 37.103...-rail vehicles by private entities primarily engaged in the business of transporting people. (a... engaged in the business of transporting people and whose operations affect commerce, in which...

  16. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... primarily in the business of transporting people. 37.195 Section 37.195 Transportation Office of the... transporting people. This section applies to all purchases or leases of new vehicles by private entities which are not primarily engaged in the business of transporting people, with respect to buses delivered...

  17. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... primarily in the business of transporting people. 37.195 Section 37.195 Transportation Office of the... transporting people. This section applies to all purchases or leases of new vehicles by private entities which are not primarily engaged in the business of transporting people, with respect to buses delivered...

  18. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... primarily in the business of transporting people. 37.195 Section 37.195 Transportation Office of the... transporting people. This section applies to all purchases or leases of new vehicles by private entities which are not primarily engaged in the business of transporting people, with respect to buses delivered...

  19. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... primarily in the business of transporting people. 37.195 Section 37.195 Transportation Office of the... transporting people. This section applies to all purchases or leases of new vehicles by private entities which are not primarily engaged in the business of transporting people, with respect to buses delivered...

  20. 49 CFR 37.103 - Purchase or lease of new non-rail vehicles by private entities primarily engaged in the business...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... private entities primarily engaged in the business of transporting people. 37.103 Section 37.103...-rail vehicles by private entities primarily engaged in the business of transporting people. (a... engaged in the business of transporting people and whose operations affect commerce, in which...

  1. 49 CFR 37.103 - Purchase or lease of new non-rail vehicles by private entities primarily engaged in the business...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... private entities primarily engaged in the business of transporting people. 37.103 Section 37.103...-rail vehicles by private entities primarily engaged in the business of transporting people. Link to an... people and whose operations affect commerce, in which a solicitation for the vehicle is made (except...

  2. TRPA1 Is Functionally Expressed Primarily by IB4-Binding, Non-Peptidergic Mouse and Rat Sensory Neurons

    PubMed Central

    Stucky, Cheryl L.

    2012-01-01

    expressed primarily in the IB4-positive, CGRP-negative subpopulation of small lumbar DRG neurons from rodents. Thus, IB4 binding is a better indicator than neuropeptides for TRPA1 expression. PMID:23133534

  3. TUMOR NECROSIS FACTOR ALPHA DECREASES NOS3 EXPRESSION PRIMARILY VIA RHO/RHO KINASE IN THE THICK ASCENDING LIMB

    PubMed Central

    Ramseyer, Vanesa; Hong, Nancy; Garvin, Jeffrey L.

    2013-01-01

    Inappropriate Na+ reabsorption by thick ascending limbs (THALs) induces hypertension. Nitric oxide (NO) produced by NO synthase type 3 (NOS3 or eNOS) inhibits NaCl reabsorption by THALs. Tumor necrosis factor alpha (TNF-α) decreases NOS3 expression in endothelial cells and contributes to increases in blood pressure. However, the effects of TNF-α on THAL NOS3 and the signaling cascade are unknown. TNF-α activates several signaling pathways including Rho/Rho kinase (ROCK) which is known to reduce NOS3 expression in endothelial cells. Therefore, we hypothesized that TNF-α decreases NOS3 expression via Rho/ROCK in rat THAL primary cultures. THAL cells were incubated with either vehicle or 1 nmol/L TNF-α for 24 hrs and NOS3 expression was measured by Western blot. TNF-α decreased NOS3 expression by 51±6% (p<0.002) and blunted stimulus-induced NO production. A 10-minutes treatment with TNF-α stimulated RhoA activity by 60±23% (p<0.04). Inhibition of Rho GTPase with 0.05 μg/mL C3 exoenzyme blocked TNF-α-induced reductions in NOS3 expression by 30±8% (p<0.02). Inhibition of ROCK with 10 μmol/L H-1152 blocked TNF-α-induced decreases in NOS3 expression by 66±15 % (p<0.001). Simultaneous inhibition of Rho and ROCK had no additive effect. Myosin light chain kinase, NO, protein kinase C, mitogen-activated kinase kinase, c-Jun amino terminal kinases and Rac-1 were also not involved in TNF-α-induced decreases in NOS3 expression. We conclude that TNF-α decreases NOS3 expression primarily via Rho/ROCK in rat THALs. These data suggest that some of the beneficial effects of ROCK inhibitors in hypertension could be due to the mitigation of TNF-α-induced reduction in NOS3 expression. PMID:22566503

  4. Virtual Rover Drives Toward Rock

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image shows a screenshot from the software used by engineers to test and drive the Mars Exploration Rover Spirit. The software simulates the rover's movements across the martian terrain, helping to plot a safe course. Here, engineers simulated Spirit's first post-egress drive on Mars Sunday. The 3-meter (10-foot) drive totaled approximately 30 minutes, including time to stop and take images. The rover drove toward its first rock target, a mountain-shaped rock called Adirondack. The blue line denotes the path of the rover's 'belly button,' as engineers like to call it, as the rover drove toward Adirondack. The virtual 3-D world around the rover was built from images taken by Spirit's stereo navigation cameras. Regions for which the rover has not yet acquired 3-D data are represented in beige.

  5. Drive: Theory and Construct Validation

    PubMed Central

    Petrides, K. V.

    2016-01-01

    This article explicates the theory of drive and describes the development and validation of two measures. A representative set of drive facets was derived from an extensive corpus of human attributes (Study 1). Operationalised using an International Personality Item Pool version (the Drive:IPIP), a three-factor model was extracted from the facets in two samples and confirmed on a third sample (Study 2). The multi-item IPIP measure showed congruence with a short form, based on single-item ratings of the facets, and both demonstrated cross-informant reliability. Evidence also supported the measures’ convergent, discriminant, concurrent, and incremental validity (Study 3). Based on very promising findings, the authors hope to initiate a stream of research in what is argued to be a rather neglected niche of individual differences and non-cognitive assessment. PMID:27409773

  6. Drive: Theory and Construct Validation.

    PubMed

    Siegling, Alex B; Petrides, K V

    2016-01-01

    This article explicates the theory of drive and describes the development and validation of two measures. A representative set of drive facets was derived from an extensive corpus of human attributes (Study 1). Operationalised using an International Personality Item Pool version (the Drive:IPIP), a three-factor model was extracted from the facets in two samples and confirmed on a third sample (Study 2). The multi-item IPIP measure showed congruence with a short form, based on single-item ratings of the facets, and both demonstrated cross-informant reliability. Evidence also supported the measures' convergent, discriminant, concurrent, and incremental validity (Study 3). Based on very promising findings, the authors hope to initiate a stream of research in what is argued to be a rather neglected niche of individual differences and non-cognitive assessment. PMID:27409773

  7. MULTIPLE DIFFERENTIAL ROTARY MECHANICAL DRIVE

    DOEpatents

    Smits, R.G.

    1964-01-28

    This patent relates to a mechanism suitable for such applications as driving two spaced-apart spools which carry a roll film strip under conditions where the film movement must be rapidly started, stopped, and reversed while maintaining a constant tension on the film. The basic drive is provided by a variable speed, reversible rnotor coupled to both spools through a first differential mechanism and driving both spools in the same direction. A second motor, providing a constant torque, is connected to the two spools through a second differential mechanism and is coupled to impart torque to one spool in a first direction anid to the other spool in the reverse direction thus applying a constant tension to the film passing over the two spools irrespective of the speed or direction of rotation thereof. (AEC)

  8. Rover Takes a Sunday Drive

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This animation, made with images from the Mars Exploration Rover Spirit hazard-identification camera, shows the rover's perspective of its first post-egress drive on Mars Sunday. Engineers drove Spirit approximately 3 meters (10 feet) toward its first rock target, a football-sized, mountain-shaped rock called Adirondack. The drive took approximately 30 minutes to complete, including time stopped to take images. Spirit first made a series of arcing turns totaling approximately 1 meter (3 feet). It then turned in place and made a series of short, straightforward movements totaling approximately 2 meters (6.5 feet).

  9. Future hard disk drive systems

    NASA Astrophysics Data System (ADS)

    Wood, Roger

    2009-03-01

    This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

  10. The onset of driving phobias.

    PubMed

    Munjack, D J

    1984-12-01

    Thirty driving phobics who called the Psychiatry Outpatient Phobia Clinic (25 females and five males) were given a 20-min semi-standardized telephone interview during which they were asked about the circumstances of the onset of their driving fears. Twelve (40%) reported that their fears were precipitated by a panic attack on the freeway; six (20%) by a collision; and three (10%) by other frightening experiences in automobiles. Four (13.3%) related the onset to family stress or upheaval. Other modes of onset also occurred. The implications of these findings are discussed in terms of existing theories of fear acquisition and treatment approaches. PMID:6526942

  11. Driving and Age-Related Macular Degeneration

    ERIC Educational Resources Information Center

    Owsley, Cynthia; McGwin, Gerald, Jr.

    2008-01-01

    This article reviews the research literature on driving and age-related macular degeneration, which is motivated by the link between driving and the quality of life of older adults and their increased collision rate. It addresses the risk of crashes, driving performance, driving difficulty, self-regulation, and interventions to enhance, safety,…

  12. Basic principles of variable speed drives

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.

    1973-01-01

    An understanding of the principles which govern variable speed drive operation is discussed for successful drive application. The fundamental factors of torque, speed ratio, and power as they relate to drive selection are discussed. The basic types of variable speed drives, their operating characteristics and their applications are also presented.

  13. Driving and Age-Related Macular Degeneration

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald

    2009-01-01

    This article reviews the research literature on driving and age-related macular degeneration, which is motivated by the link between driving and the quality of life of older adults and their increased collision rate. It addresses the risk of crashes, driving performance, driving difficulty, self-regulation, and interventions to enhance, safety, and considers directions for future research. PMID:20046818

  14. Electronic 4-wheel drive control device

    NASA Technical Reports Server (NTRS)

    Hayato, S.; Takanori, S.; Shigeru, H.; Tatsunori, S.

    1984-01-01

    The internal rotation torque generated during operation of a 4-wheel drive vehicle is reduced using a control device whose clutch is attached to one part of the rear-wheel drive shaft. One torque sensor senses the drive torque associated with the rear wheel drive shaft. A second sensor senses the drive torque associated with the front wheel drive shaft. Revolution count sensors sense the revolutions of each drive shaft. By means of a microcomputer, the engagement of the clutch is changed to insure that the ratio of the torque sensors remains constant.

  15. Drive reconfiguration mechanism for tracked robotic vehicle

    DOEpatents

    Willis, W. David

    2000-01-01

    Drive reconfiguration apparatus for changing the configuration of a drive unit with respect to a vehicle body may comprise a guide system associated with the vehicle body and the drive unit which allows the drive unit to rotate about a center of rotation that is located at about a point where the drive unit contacts the surface being traversed. An actuator mounted to the vehicle body and connected to the drive unit rotates the drive unit about the center of rotation between a first position and a second position.

  16. Promising Electric Aircraft Drive Systems

    NASA Technical Reports Server (NTRS)

    Dudley, Michael R.

    2010-01-01

    An overview of electric aircraft propulsion technology performance thresholds for key power system components is presented. A weight comparison of electric drive systems with equivalent total delivered energy is made to help identify component performance requirements, and promising research and development opportunities.

  17. Virtual Rewards for Driving Green

    ERIC Educational Resources Information Center

    Pritchard, Josh

    2010-01-01

    Carbon dioxide from automobiles is a major contributor to global climate change. In "Virtual Rewards for Driving Green," Josh Pritchard proposes a computer application that will enable fuel-efficient drivers to earn "green" dollars with which to buy digital merchandise on the Web. Can getting items that exist only in cyberspace actually change a…

  18. Anomalous-viscosity current drive

    DOEpatents

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  19. Test-Driving Their Passions

    ERIC Educational Resources Information Center

    Davis, Noah

    2007-01-01

    This article describes how the Watson fellowships give recipients an opportunity to test-drive their passions and see if they could lead to a career path. Over the last 40 years, the Thomas J. Watson Foundation has awarded $29 million in fellowships to seniors graduating from 50 mostly top-tier colleges with fewer than 3,000 students. In 2007, 50…

  20. Driving and working with syncope.

    PubMed

    Barbic, Franca; Casazza, Giovanni; Zamunér, Antonio Roberto; Costantino, Giorgio; Orlandi, Mauro; Dipaola, Franca; Capitanio, Chiara; Achenza, Sara; Sheldon, Robert; Furlan, Raffaello

    2014-09-01

    Syncope is usually addressed in the Emergency Department (ED) by the doctor in charge of the clinical picture, i.e. the patient's risk is stratified, a diagnostic work-up is done and a prognosis is set. Patients are ultimately admitted to hospital or discharged. However, other aspects related to syncope may deeply affect their daily lives. These include how and when to return to work and to driving, the feelings about a recent loss of consciousness, and the potential relapse of syncope. This is particularly significant if the work setting is intrinsically hazardous. These patients need adequate clinical and psychological support. For patients with syncope, two main parameters should be considered regarding returning to work and to driving. The first is to evaluate the risk of syncope recurrence and the second is to consider the expected harm if syncope does indeed occur during these activities. In the present paper we detail the problem of driving (including professional driving) and work after syncope. We propose a new quantitative model that will guide the physician in stratifying the risk for patients who have had a previous syncope event. The new model considers the syncope recurrence risk, the job task duration, and features that facilitate a syncope during work. On the basis of these variables, the global risk index for a worker is calculated. Following appropriate validation, this method might help ED and occupational physicians in their decision-making process with the goal of safely readmitting syncope patients to the workplace. PMID:24881013

  1. Driving Competencies for the Elderly.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Continuing Education Curriculum Development.

    Designed for use by directors of senior citizen groups, continuing education directors, and driver education instructors, this manual suggests a course outline, subject content, and instructional materials for effectively teaching a refresher driving course. The first seven topics represent the basic content and none should be omitted: orientation…

  2. Hydromechanical transmission with hydrodynamic drive

    DOEpatents

    Orshansky, Jr., deceased, Elias; Weseloh, William E.

    1979-01-01

    This transmission has a first planetary gear assembly having first input means connected to an input shaft, first output means, and first reaction means, and a second planetary gear assembly having second input means connected to the first input means, second output means, and second reaction means connected directly to the first reaction means by a reaction shaft. First clutch means, when engaged, connect the first output means to an output shaft in a high driving range. A hydrodynamic drive is used; for example, a torque converter, which may or may not have a stationary case, has a pump connected to the second output means, a stator grounded by an overrunning clutch to the case, and a turbine connected to an output member, and may be used in a starting phase. Alternatively, a fluid coupling or other type of hydrodynamic drive may be used. Second clutch means, when engaged, for connecting the output member to the output shaft in a low driving range. A variable-displacement hydraulic unit is mechanically connected to the input shaft, and a fixed-displacement hydraulic unit is mechanically connected to the reaction shaft. The hydraulic units are hydraulically connected together so that when one operates as a pump the other acts as a motor, and vice versa. Both clutch means are connected to the output shaft through a forward-reverse shift arrangement. It is possible to lock out the torque converter after the starting phase is over.

  3. Cannabis Effects on Driving Skills

    PubMed Central

    Hartman, Rebecca L.; Huestis, Marilyn A.

    2013-01-01

    BACKGROUND Cannabis is the most prevalent illicit drug identified in impaired drivers. The effects of cannabis on driving continue to be debated, making prosecution and legislation difficult. Historically, delays in sample collection, evaluating the inactive Δ9-tetrahydrocannabinol (THC) metabolite 11-nor-9-carboxy-THC, and polydrug use have complicated epidemiologic evaluations of driver impairment after cannabis use. CONTENT We review and evaluate the current literature on cannabis’ effects on driving, highlighting the epidemiologic and experimental data. Epidemiologic data show that the risk of involvement in a motor vehicle accident (MVA) increases approximately 2-fold after cannabis smoking. The adjusted risk of driver culpability also increases substantially, particularly with increased blood THC concentrations. Studies that have used urine as the biological matrix have not shown an association between cannabis and crash risk. Experimental data show that drivers attempt to compensate by driving more slowly after smoking cannabis, but control deteriorates with increasing task complexity. Cannabis smoking increases lane weaving and impaired cognitive function. Critical-tracking tests, reaction times, divided-attention tasks, and lane-position variability all show cannabis-induced impairment. Despite purported tolerance in frequent smokers, complex tasks still show impairment. Combining cannabis with alcohol enhances impairment, especially lane weaving. SUMMARY Differences in study designs frequently account for inconsistencies in results between studies. Participant-selection bias and confounding factors attenuate ostensible cannabis effects, but the association with MVA often retains significance. Evidence suggests recent smoking and/or blood THC concentrations 2–5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Future cannabis-and-driving research should emphasize challenging tasks, such as divided attention

  4. Neural substrates of driving behaviour

    PubMed Central

    Spiers, Hugo J.; Maguire, Eleanor A.

    2007-01-01

    Driving a vehicle is an indispensable daily behaviour for many people, yet we know little about how it is supported by the brain. Given that driving in the real world involves the engagement of many cognitive systems that rapidly change to meet varying environmental demands, identifying its neural basis presents substantial problems. By employing a unique combination of functional magnetic resonance imaging (fMRI), an accurate interactive virtual simulation of a bustling central London (UK) and a retrospective verbal report protocol, we surmounted these difficulties. We identified different events that characterise the driving process on a second by second basis and the brain regions that underlie them. Prepared actions such as starting, turning, reversing and stopping were associated with a common network comprised of premotor, parietal and cerebellar regions. Each prepared action also recruited additional brain areas. We also observed unexpected hazardous events such as swerving and avoiding collisions that were associated with activation of lateral occipital and parietal regions, insula, as well as a more posterior region in the medial premotor cortex than prepared actions. By contrast, planning future actions and monitoring fellow road users were associated with activity in superior parietal, lateral occipital cortices and the cerebellum. The anterior pre-SMA was also recruited during action planning. The right lateral prefrontal cortex was specifically engaged during the processing of road traffic rules. By systematically characterising the brain dynamics underlying naturalistic driving behaviour in a real city, our findings may have implications for how driving competence is considered in the context of neurological damage. PMID:17412611

  5. Configuring the National Ignition Facility for direct-drive experiments

    SciTech Connect

    Eimerl, D.

    1995-07-01

    The National Ignition Facility (NIF) is a project whose primary mission is to provide an above-ground experimental capability for maintaining nuclear competence and weapons effects simulation, and to pursue the achievement of fusion ignition utilizing solid state lasers as the energy driver. In this facility a large number of laser beams are focused onto a small target located at the center of a spherical target chamber. The laser energy is delivered in a few billionths of a second, raising the temperature and density of the nuclear materials in the target to levels where significant thermonuclear energy is released. The thermonuclear reaction proceeds very rapidly, so that the target materials remain confined by their own inertia during the thermonuclear reaction. This type of approach is called inertial confinement fusion (ICF). The proposed project is described in a conceptual design report (CDR) that was released in May 1994. Early in FY95, a collaboration between the University of Rochester and the Lawrence Livermore National Laboratory was established to study reconfiguring the NIF to accommodate direct-drive experiments. The present paper is a report to the scientific community, primarily the scientists and engineers working on the design of the NIF. It represents results from work in progress, specifically work completed by the end of the second quarter FY95. This report has two main sections. The first describes the target requirements on the laser drive, and the second part describes how the NIF laser can be configured to accommodate both indirect and direct drive. The report includes a description of the scientific basis for these conclusions. Though a complete picture does not exist, the present understanding is sufficient to conclude that the primary target requirements and laser functional requirements for indirect and direct drive are quite compatible. It is evidently straightforward to reconfigure the NIF to accommodate direct and indirect drive.

  6. Driving with Hemianopia, I: Detection Performance in a Driving Simulator

    PubMed Central

    Bowers, Alex R.; Mandel, Aaron J.; Goldstein, Robert B.; Peli, Eli

    2009-01-01

    Purpose This study was designed to examine the effect of homonymous hemianopia (HH) on detection of pedestrian figures in multiple realistic and hazardous situations within the controlled environment of a driving simulator. Methods Twelve people with complete HH and without visual neglect or cognitive decline and 12 matched (age, sex, and years of driving experience) normally sighted (NV) drivers participated. They drove predetermined city and rural highway routes (total, 120 minutes) during which pedestrian figures appeared at random intervals along the roadway (R-Peds; n = 144) and at intersections (I-Peds; n = 10). Detection rates and response times were derived from participant horn presses. Results Drivers with HH exhibited significantly (P < 0.001) lower R-Ped detection rates on the blind side than did NV drivers (range, 6%–100%). Detection of I-Peds on the blind side was also poor (8%–55%). Age and blind-side detection rates correlated negatively (Spearman r = −0.71, P = 0.009). Although blind-side response times of drivers with HH were significantly (P < 0.001) longer than those of NV drivers, most were within a commonly used 2.5-second guideline. Conclusions Most participants with HH had blind-side detection rates that seem incompatible with safe driving; however, the relationship of our simulator detection performance measures to on-road performance has yet to be established. In determining fitness to drive for people with HH, the results underscore the importance of individualized assessments including evaluations of blind-side hazard detection. PMID:19608541

  7. The chemical biology of methanogenesis

    NASA Astrophysics Data System (ADS)

    Ferry, James G.

    2010-12-01

    Two distinct pathways account for most of the CH 4 produced in the majority of the diverse and vast anaerobic environments of Earth's biosphere by microbes that are classified in the Archaea domain of life: conversion of the methyl group of acetate to CH 4 in the aceticlastic pathway and reduction of CO 2 with electrons derived from H 2, formate or CO in the CO 2 reduction pathway. Minor, albeit ecologically important, amounts of CH 4 are produced by conversion of methylotrophic substrates methanol, methylamines and methyl sulfides. Although all pathways have terminal steps in common, they deviate in the initial steps leading to CH 4 and mechanisms for synthesizing ATP for growth. Hydrogen gas is the major reductant for CO 2-reducing methanogens in the deep subsurface, although H 2 is also utilized by CO 2-reducing microbes from the Bacteria domain that produce acetate for the aceticlastic methanogens. This review presents fundamentals of the two major CH 4-producing pathways with a focus on understanding the potential for biologically-produced CH 4 on Mars.

  8. [Driving fitness/driving capacity of patients treated with methadone].

    PubMed

    Hauri-Bionda, R; Bär, W; Friedrich-Koch, A

    1998-10-10

    To answer the question whether or not therapeutic methadone doses significantly reduce traffic-related performance of drivers on medically supervised methadone programmes, 34 methadone substitution patients, all of them volunteers, were subjected to a test series: the focus of the study was a psychophysical test battery consisting of 10 individual performance tests to assess essential functions with regard to driving ability, such as concentration, attention, reaction capability, memory, perception and sensorimotor coordination. In evaluating the results of the psychophysical tests, multiple drug use and subjective methadone influence at the time of the examination were taken into consideration but current methadone blood level was neglected. The results were compared to those of a control group. The methadone group (n = 34) consisted of 25 men and 9 women aged between 18 and 38. At the time of the study, the majority of the test persons (29) were on low dosage methadone maintenance (up to 60 mg/day). In the urine samples of approximately 2/3 of the test persons, evidence was found for multiple drug use together with other psychotropic substances, the most frequent (14) being cannabis metabolites. Referring to their driving practices, a mere 4 out of 29 drivers had not committed any driving offences. A comparison of the psychophysical performance of the whole methadone group (n = 34) with a control group demonstrated that the methadone substitution patients achieved rather lower results in almost all variables. These performance deficits were particularly conspicuous in sustained attention, sensorimotor coordination and reaction capability. 12 "methadone only" participants, i.e. methadone probands without any additional consumption of psychotropic substances showed-partly considerably-better performance than the methadone group as a whole and also achieved normal results in relation to the test norm. Nevertheless, once again, results tended to be of lower level in

  9. Magnetically Coupled Adjustable Speed Drive Systems

    SciTech Connect

    Chvala, William D.; Winiarski, David W.

    2002-08-18

    Adjustable speed drive (ASD) technologies have the ability to precisely control motor sytems output and produce a numbr of benefits including energy and demand savings. This report examines the performance and cost effectiveness of a specific class of ASDs called magnetically-coupled adjustable speed drives (MC-ASD) which use the strength of a magnetic field to control the amount of torque transferred between motor and drive shaft. The MagnaDrive Adjustable Speed Coupling System uses fixed rare-earth magnets and varies the distance between rotating plates in the assembly. the PAYBACK Variable Speed Drive uses an electromagnet to control the speed of the drive

  10. Warp Drive - A New Approach

    NASA Astrophysics Data System (ADS)

    Obousy, R. K.; Cleaver, G.

    Certain classes of higher dimensional models suggest that the Casimir Effect is a candidate for the cosmological constant. In this paper we demonstrate that a sufficiently advanced civilization could, in principal, manipulate the radius of the extra dimension to locally adjust the value of the cosmological constant. This adjustment could be tuned to generate an expansion/ contraction of spacetime around a spacecraft creating an exotic form of field-propulsion. Due to the fact that spacetime expansion itself is not restricted by relativity, a faster-than-light `warp drive' could be created. Calculations of the energy requirements of such a drive are performed and an `ultimate' speed limit, based on the Planckian limits on the size of the extra dimensions is found.

  11. Conditional dynamics driving financial markets

    NASA Astrophysics Data System (ADS)

    Boguñá, M.; Masoliver, J.

    2004-08-01

    We revisit the problem of daily correlations in speculative prices and report empirical evidences on the existence of what we term a conditional or dual dynamics driving the evolution of financial assets. This dynamics is detected in several markets around the world and for different historical periods. In particular, we have analyzed the DJIA database from 1900 to 2002 as well as 65 companies trading in the LIFFE market of futures and 12 of the major European and American treasury bonds. In all cases, we find a twofold dynamics driving the financial evolution depending on whether the previous price went up or down. We conjecture that this effect is universal and intrinsic to all markets.

  12. [Daytime sleepiness and driving behaviour].

    PubMed

    Mathis, Johannes; Schreier, David

    2014-11-01

    Daytime sleepiness is reported by 10-15 % within the general population of industrialised countries. According to federal statistics in Switzerland, only ~1.5 % of motor vehicle crashes are caused by excessive daytime sleepiness, which is in sharp contrast to the scientific literature, indicating a figure of 10 to 30 %. This is most likely related to the difficulty to detect the underlying sleepiness by police officers and their low awareness of this cause in case of car accidents. As a consequence of this massively reduced figure, the real problem is underestimated and countermeasures as well as examinations of drivers at fault are inadequately realised in our country. The risk factors for sleepiness induced accidents are young age, male sex, driving at night or long distances and a number of diseases or sedative drugs. The most prevalent cause of sleepiness related accidents is the behaviourally induced sleep insufficiency syndrome or irregular sleep-wake rhythm in otherwise healthy subjects. Disease related sleepiness which may also cause motor vehicle accidents must be managed by physicians. In the diagnostic work-up sedative drugs, medical causes of sleepiness or tiredness as well as primary sleep-wake disorders must be considered. The most important duty of the treating physician, in addition to correct diagnosis and treatment, is to inform the affected patient of his or her responsibility not to drive while sleepy, about the theoretical legal consequences in case of an accident and about efficient countermeasures such as stopping in a rest area, drinking coffee, and taking a nap. For legal reasons, this information must be written in the patient's notes. Professional drivers suffering from sleep apnoea syndrome or other disorders with excessive daytime sleepiness, or private drivers who have already experienced a sleepiness induced accident, should be referred to a sleep-wake-centre for objective assessment of their sleepiness in the maintenance of

  13. Embedded sensor node deployment to monitor telescope drive system components

    NASA Astrophysics Data System (ADS)

    Taylor, Stuart G.; Stull, Christopher J.; Wren, James; Raby, Eric Y.; Farrar, Charles R.

    2012-04-01

    This paper presents the deployment of an embedded active sensing platform for real-time condition monitoring of telescopes in the RAPid Telescopes for Optical Response (RAPTOR) observatory network. The RAPTOR network consists of several ground-based autonomous astronomical observatories primarily designed to search for astrophysical transients such as gamma-ray bursts. In order to capture astrophysical transients of interest, the telescopes must remain in peak operating condition to move swiftly from one potential transient to the next throughout the night. However, certain components of these telescopes have until recently been maintained in an ad hoc manner, often being permitted to run to failure, resulting in the inability to drive the telescope. In a recent study, a damage classifier was developed using the statistical pattern recognition paradigm of structural health monitoring (SHM) to identify the onset of damage in critical telescope drive components. In this work, a prototype embedded active sensing platform is deployed to the telescope structure in order to record data for use in detecting the onset of telescope drive component damage and alert system administrators prior to system failure.

  14. Electric vehicle drive train components

    SciTech Connect

    Silver, F.

    1994-12-31

    Power Control Systems has developed a family of electric vehicle drive systems that range from 65 horsepower through 300 horse power. These propulsion systems support vehicle applications ranging from light cars and pickups to buses and trucks weighing as much as 40,000 lbs (18,400 kg). These robust systems are designed specifically for automotive applications including safety, electromagnetic emissions, and environment ruggedness. Dolphin Drive Systems are very flexible. Their inverter controllers are programmable and can be provided as stand alone components matched to customer specified motors. A selection of pre-calibrated systems including motor and inverter/controller can be provided. Accessory tools are also available for customer self programming. Dolphin Drive Systems provide precision control of AC induction motors providing excellent torque-speed performance usually eliminating the need for multistage transmissions. In addition, they are very efficient over a wide speed/torque range. This provides for excellent power management over a variety of continuous speed and stop and go applications.

  15. Warp drive space-time

    NASA Astrophysics Data System (ADS)

    González-Díaz, Pedro F.

    2000-08-01

    In this paper the problem of the quantum stability of the two-dimensional warp drive spacetime moving with an apparent faster than light velocity is considered. We regard as a maximum extension beyond the event horizon of that spacetime its embedding in a three-dimensional Minkowskian space with the topology of the corresponding Misner space. It is obtained that the interior of the spaceship bubble becomes then a multiply connected nonchronal region with closed spacelike curves and that the most natural vacuum allows quantum fluctuations which do not induce any divergent behavior of the renormalized stress-energy tensor, even on the event (Cauchy) chronology horizon. In such a case, the horizon encloses closed timelike curves only at scales close to the Planck length, so that the warp drive satisfies Ford's negative energy-time inequality. Also found is a connection between the superluminal two-dimensional warp drive space and two-dimensional gravitational kinks. This connection allows us to generalize the considered Alcubierre metric to a standard, nonstatic metric which is only describable on two different coordinate patches.

  16. Effect of cognitive status on self-regulatory driving behavior in older adults: an assessment of naturalistic driving using in-car video recordings.

    PubMed

    Festa, Elena K; Ott, Brian R; Manning, Kevin J; Davis, Jennifer D; Heindel, William C

    2013-03-01

    Previous findings that older drivers engage in strategic self-regulatory behaviors to minimize perceived safety risks are primarily based on survey reports rather than actual behavior. This study analyzed in-car video recording of naturalistic driving of 18 patients with Alzheimer disease (AD) and 20 age-matched controls in order to (1) characterize self-regulatory behaviors engaged by older drivers and (2) assess how behaviors change with cognitive impairment. Only participants who were rated "safe" on a prior standardized road test were selected for this study. Both groups drove primarily in environments that minimized the demands on driving skill and that incurred the least risk for involvement in major crashes. Patients with AD displayed further restrictions of driving behavior beyond those of healthy elderly individuals, suggesting additional regulation on the basis of cognitive status. These data provide critical empirical support for findings from previous survey studies indicating an overall reduction in driving mobility among older drivers with cognitive impairment. PMID:23385363

  17. Development of a driving cycle for intra-city buses in Chennai, India

    NASA Astrophysics Data System (ADS)

    Nesamani, K. S.; Subramanian, K. P.

    2011-10-01

    In India the emissions rate and fuel consumption of intra-city buses are estimated using the European driving cycles, which don't represent Indian driving conditions and in-use operation of vehicles. This leads to underestimation or overestimation of emissions and fuel consumption. In this context, this paper offers some insight into the driving characteristics of intra-city buses using a Global Positioning System. The study has revealed that irrespective of road type and time of travel, a higher percentage of time is spent in idle mode. This is primarily due to alighting and boarding of passengers at regular intervals and fixed delays caused by traffic lights. More than 90 percent of trips have an average speed of less than 30 km h -1. This study has also developed an intra-city bus driving cycle for Chennai and compared it with some well-known international driving cycles. It has revealed that Chennai has unique driving characteristics and, therefore, it may not be appropriate to adopt a driving cycle of another country or city.

  18. Behavioral Impact of Graduated Driver Licensing on Teenage Driving Risk and Exposure1

    PubMed Central

    Karaca-Mandic, Pinar; Ridgeway, Greg

    2009-01-01

    Graduated Driver Licensing (GDL) is a critical policy tool for potentially improving teenage driving while reducing teen accident exposure. While previous studies demonstrated that GDL reduces teenage involvement in fatal crashes, much remains unanswered. We explore the mechanisms through which GDL influences accident rates as well as its long term effectiveness on teen driving. In particular, we investigate; 1) whether GDL policies improve teenage driving behavior, or simply reduce teenage prevalence on the roads; 2) whether GDL exposed teens become better drivers in later years. We employ a unique data source, the State Data System, which contains all police reported accidents (fatal and non-fatal) during 1990–2005 for twelve states. We estimate a structural model that separately identifies GDL s effect on relative teenage prevalence and relative teenage riskiness. Identification of the model is driven by the relative numbers of crashes between two teenagers, two adults, or a teenager and an adult. We find that the GDL policies reduce the number of 15–17 year-old accidents by limiting the amount of teenage driving rather than by improving teenage driving. This prevalence reduction primarily occurs at night and stricter GDL policies, especially those with nighttime driving restrictions, are the most effective. Finally, we find that teen driving quality does not improve ex-post GDL exposure. PMID:19942310

  19. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing...

  20. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing...

  1. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 77.406 Section 77.406 Mineral... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  2. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 77.406 Section 77.406 Mineral... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  3. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 77.406 Section 77.406 Mineral... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  4. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing...

  5. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drive belts. 77.406 Section 77.406 Mineral... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  6. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing...

  7. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral... SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing...

  8. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drive belts. 77.406 Section 77.406 Mineral... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless the machines are provided with mechanical shifters. (b) Belt dressing shall not be applied while belts are...

  9. Evidence for meiotic drive at the myotonic dystrophy locus

    SciTech Connect

    Shaw, A.M.; Barnetson, R.A.; Phillips, M.F.

    1994-09-01

    Myotonic dystrophy (DM), an autosomal dominant disorder, is the most common form of adult muscular dystrophy, affecting at least 1 in 8000 of the population. It is a multisystemic disorder, primarily characterized by myotonia, muscle wasting and cataract. The molecular basis of DM is an expanded CTG repeat located within the 3{prime} untranslated region of a putative serine-threonine protein kinase on chromosome 19q13.3. DM exhibits anticipation, that is, with successive generations there is increasing disease severity and earlier age of onset. This mechanism and the fact that the origin of the disease has been attributed to one or a small number of founder chromosomes suggests that, in time, DM should die out. Meiotic drive has been described as a way in which certain alleles are transmitted to succeeding generations in preference to others: preferential transmission of large CTG alleles may account for their continued existence in the gene pool. There is evidence that a CTG allele with > 19 repeats may gradually increase in repeat number over many generations until it is sufficiently large to give a DM phenotype. We report a study of 495 transmissions from individuals heterozygous for the CTG repeat and with repeat numbers within the normal range (5-30). Alleles were simply classified as large or small relative to the other allele in an individual. Of 242 male meioses, 126 transmissions from parent to child were of the larger allele to their offspring (57.7%, p=0.014). This shows that there is strong evidence for meiotic drive favoring the transmission of the larger DM allele in unaffected individuals. Contrary to a previous report of meiotic drive in the male, we have shown that females preferentially transmit the larger DM allele. Taken together, the data suggest the occurrence of meiotic drive in both males and females in this locus.

  10. Driving trajectories in chaotic scattering.

    PubMed

    Macau, Elbert E N; Caldas, Iberê L

    2002-02-01

    In this work we introduce a general approach for targeting in chaotic scattering that can be used to find a transfer trajectory between any two points located inside the scattering region. We show that this method can be used in association with a control of chaos strategy to drive around and keep a particle inside the scattering region. As an illustration of how powerful this approach is, we use it in a case of practical interest in celestial mechanics in which it is desired to control the evolution of two satellites that evolve around a large central body. PMID:11863640

  11. Computer-Aided Remote Driving

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H.

    1994-01-01

    System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

  12. Fluid cooled vehicle drive module

    DOEpatents

    Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

    2005-11-15

    An electric vehicle drive includes a support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EM/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  13. Efficient alternatives for electric drives

    SciTech Connect

    Comnes, G.A.; Barnes, R.W.

    1987-11-01

    This analysis of industrial electric motors describes the current motor stock, its energy use and operating characteristics, and innovations that could change current use patterns. It provides calculations characterizing the economic attractiveness of several existing and potential options. One attractive option given particular attention is the adjustable-speed drive which can replace throttles or valves for many pumping operations. A major conclusion is that, throughout industry, options that are both energy-saving and economically attractive appear to penetrate markets more slowly than would be socially optimal. The final section examines characteristics of industry that may contribute to slow market penetration. 29 refs., 14 figs., 14 tabs.

  14. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  15. Voight variable speed drive. [for windpowered generator

    NASA Technical Reports Server (NTRS)

    Tompkin, J.

    1973-01-01

    The variable speed drive transmission is mounted within the gondola and connected with the wind turbine blades and the hub. This unit is designed for the production of ac power. The turbine turns by means of the variable speed drive and a set of synchronous three phase generators. This motion is controlled automatically by two wind rosettes in such a way that the wind turbine always opposes the wind direction. The Voight variable speed drive is a mechanical variable positive drive gear transmission. It has an unlimited power and torque transmission, a constant ratio with high degree of accuracy, a speed variation over a wide range, and a nonslip drive.

  16. Perceptual and Cognitive Impairments and Driving

    PubMed Central

    Korner-Bitensky, Nicol; Coopersmith, Henry; Mayo, Nancy; Leblanc, Ginette; Kaizer, Franceen

    1990-01-01

    Perceptual and cognitive disorders that frequently accompany stroke and head injury influence an individual's ability to drive a motor vehicle. Canadian physicians are legally responsible for identifying patients who are potentially unsafe to drive and, if they fail to do so, may be held liable in a civil action suit. The authors review the guidelines for physicians evaluating a patient's fitness to drive after brain injury. They also examine the actions a physician should take when a patient with perceptual and cognitive problems wants to drive. Ultimately, by taking these actions, physicians will help to prevent driving accidents. PMID:21234047

  17. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  18. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  19. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  20. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  1. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  2. Four-wheel drive car

    SciTech Connect

    Ashikawa, N.

    1986-03-25

    A drive train in a four-wheel drive vehicle is described having an engine mounted on one end with a crankshaft oriented transverse to the direction of vehicle travel which consists of: a transmission having an output gear driven by the crankshaft and rotatable around an axis parallel to the axis of the crankshaft; a reduction gear operatively engaged with the output gear; a first differential gear having a gear and being concentrically engaged with the reduction gear to transmit the output of the reduction gear in a divided manner; a second differential gear transmitting power from one output of the differential gear to left and right wheels of the one end of the vehicle; a transmission gear meshing with the gear of the first differential gear for transmitting power from another output of the first differential gear in a direction generally perpendicular to the crankshaft through a propeller shaft to the other end of the vehicle, opposite the one end; a third differential gear receiving power from the propeller shaft for transmitting power to left and right wheels on the other end; and wherein a mesh portion where the transmission gear meshes with the gear of the first differential gear is closer to the crankshaft axis of engine than is the axis of the reduction gear.

  3. Current drive by helicon waves

    SciTech Connect

    Paul, Manash Kumar; Bora, Dhiraj

    2009-01-01

    Helicity in the dynamo field components of helicon wave is examined during the novel study of wave induced helicity current drive. Strong poloidal asymmetry in the wave magnetic field components is observed during helicon discharges formed in a toroidal vacuum chamber of small aspect ratio. High frequency regime is chosen to increase the phase velocity of helicon waves which in turn minimizes the resonant wave-particle interactions and enhances the contribution of the nonresonant current drive mechanisms. Owing to the strong poloidal asymmetry in the wave magnetic field structures, plasma current is driven mostly by the dynamo-electric-field, which arise due to the wave helicity injection by helicon waves. Small, yet finite contribution from the suppressed wave-particle resonance cannot be ruled out in the operational regime examined. A brief discussion on the parametric dependence of plasma current along with numerical estimations of nonresonant components is presented. A close agreement between the numerical estimation and measured plasma current magnitude is obtained during the present investigation.

  4. Driving Extreme Efficiency to Market

    NASA Astrophysics Data System (ADS)

    Garbesi, Karina

    2014-03-01

    The rapid development of extremely energy efficient appliances and equipment is essential to curtail catastrophic climate disruption. This will require the on-going development of products that apply all best-practices and that take advantage of the synergies of hybridization and building integration. Beyond that, it requires the development of new disruptive technologies and concepts. To facilitate these goals, in 2011 the Lawrence Berkeley National Laboratory and the U.S. Department of Energy launched the Max Tech and Beyond Design Competition for Ultra-Low-Energy-Use Appliances and Equipment. Now in its third year, the competition supports faculty-lead student design teams at U.S. universities to develop and test new technology prototypes. This talk describes what the competition and the Max Tech Program are doing to drive such rapid technology progress and to facilitate the entry to the market of successful Max Tech prototypes. The talk also initiates a discussion of physicists' unique role in driving that technology progress faster and farther. Emerging Technologies, Building Technologies Office, U.S. Department of Energy.

  5. Nanoparticles affect PCR primarily via surface interactions with PCR components: using amino-modified silica-coated magnetic nanoparticles as a main model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nanomaterials have been widely reported to affect the polymerase chain reaction (PCR). However, many studies in which these effects were observed were not comprehensive, and many of the proposed mechanisms have been primarily speculative. In this work, we used amino-modified silica-coated magnetic n...

  6. Exposure to Movie Reckless Driving in Early Adolescence Predicts Reckless, but Not Inattentive Driving

    PubMed Central

    Kostermans, Evelien; Stoolmiller, Mike; de Leeuw, Rebecca N. H.; Engels, Rutger C. M. E.; Sargent, James D.

    2014-01-01

    Objective We examine the association between exposure to depictions of reckless driving in movies and unsafe driving, modeling inattentive and reckless driving as separate outcomes. Methods Data were obtained by telephone from 1,630 US adolescents aged 10 to 14 years at baseline who were drivers at a survey 6 years later. Exposure to movie reckless driving was measured based on movies seen from a randomly selected list of 50 movie titles that had been content coded for reckless driving among characters. Associations were tested with inattentive and reckless driving behaviors in the subsequent survey–controlling for baseline age, sex, socioeconomic status, parental education, school performance, extracurricular activities, daily television and video/computer game exposure, number of movies watched per week, self-regulation and sensation seeking. Results Exposure to movie reckless driving was common, with approximately 10% of movie characters having driven recklessly. Confirmatory factor analysis revealed a significant distinction between items tapping reckless and inattentive driving at the 6th wave. Age and exposure to movie reckless driving at baseline were directly associated with wave-6 reckless (but not inattentive) driving. Additionally, growth in sensation seeking mediated a prospective relation between the total number of movies watched per week at baseline and reckless driving, independent of exposure to movie reckless driving. Males and high sensation seekers reported lower seatbelt usage and more reckless driving, whereas lower self-regulation predicted inattentive driving. Discussion In this study, exposure to movie reckless driving during early adolescence predicted adolescents’ reckless driving, suggesting a direct modeling effect. Other aspects of movies were also associated with reckless driving, with that association mediated through growth in sensation seeking. Predictors of reckless driving were different from predictors of inattentive driving

  7. Circuit for Driving Piezoelectric Transducers

    NASA Technical Reports Server (NTRS)

    Randall, David P.; Chapsky, Jacob

    2009-01-01

    The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the

  8. Optimizing digital 8mm drive performance

    NASA Technical Reports Server (NTRS)

    Schadegg, Gerry

    1993-01-01

    The experience of attaching over 350,000 digital 8mm drives to 85-plus system platforms has uncovered many factors which can reduce cartridge capacity or drive throughput, reduce reliability, affect cartridge archivability and actually shorten drive life. Some are unique to an installation. Others result from how the system is set up to talk to the drive. Many stem from how applications use the drive, the work load that's present, the kind of media used and, very important, the kind of cleaning program in place. Digital 8mm drives record data at densities that rival those of disk technology. Even with technology this advanced, they are extremely robust and, given proper usage, care and media, should reward the user with a long productive life. The 8mm drive will give its best performance using high-quality 'data grade' media. Even though it costs more, good 'data grade' media can sustain the reliability and rigorous needs of a data storage environment and, with proper care, give users an archival life of 30 years or more. Various factors, taken individually, may not necessarily produce performance or reliability problems. Taken in combination, their effects can compound, resulting in rapid reductions in a drive's serviceable life, cartridge capacity, or drive performance. The key to managing media is determining the importance one places upon their recorded data and, subsequently, setting media usage guidelines that can deliver data reliability. Various options one can implement to optimize digital 8mm drive performance are explored.

  9. [Useful assessment for identifying unsafe driving].

    PubMed

    Gonthier, Régis; Fabrigoule, Colette; Domont, Alain

    2005-03-01

    Ability to drive safely is the resultant of interactions between the individual (the driver), the vector (the car) and the environment (the state of the road). For some aged drivers, an important decline of visual, musculosquelettic and cognitive performances, may affect the ability to drive and increase the rate of crashes per vehicle-kilometer-driven, and the morbidity and mortality related to crash. Therefore, each holder of a driving licence should be medically suited to control his driving ability. In case of transitory or lasting driving incapacity, drivers must, of their own initiative, stop driving according to the Highway code and the contractual obligations appearing in their vehicle insurance contract. A medical examination for aptitude to driving requires a standardized, reliable, reproducible procedure based on consensual assessment tools to avoid arbitrary decisions for driving cessation. We propose a multidisciplinary approach to detect important decline of visuospatial and motor skills, paroxystic drops of attention and vigilance, and decreased cognitive capacity to anticipate and adapt driving at every moment. This assessment is based on a semi-directed interview and simple diagnostic tests. According to the present French law, only twelve medical conditions or functional deficits are inconsistent with the retain of the driving licence for a light vehicle. PMID:15814324

  10. Driving, brain injury and assistive technology.

    PubMed

    Lane, Amy K; Benoit, Dana

    2011-01-01

    Individuals with brain injury often present with cognitive, physical and emotional impairments which impact their ability to resume independence in activities of daily living. Of those activities, the resumption of driving privileges is cited as one of the greatest concerns by survivors of brain injury. The integration of driving fundamentals within the hierarchical model proposed by Keskinen represents the complexity of skills and behaviors necessary for driving. This paper provides a brief review of specific considerations concerning the driver with TBI and highlights current vehicle technology which has been developed by the automotive industry and by manufacturers of adaptive driving equipment that may facilitate the driving task. Adaptive equipment technology allows for compensation of a variety of operational deficits, whereas technological advances within the automotive industry provide drivers with improved safety and information systems. However, research has not yet supported the use of such intelligent transportation systems or advanced driving systems for drivers with brain injury. Although technologies are intended to improve the safety of drivers within the general population, the potential of negative consequences for drivers with brain injury must be considered. Ultimately, a comprehensive driving evaluation and training by a driving rehabilitation specialist is recommended for individuals with brain injury. An understanding of the potential impact of TBI on driving-related skills and knowledge of current adaptive equipment and technology is imperative to determine whether return-to-driving is a realistic and achievable goal for the individual with TBI. PMID:21558628

  11. Alertness maintaining tasks (AMTs) while driving.

    PubMed

    Oron-Gilad, Tal; Ronen, Adi; Shinar, David

    2008-05-01

    We evaluated the effectiveness of alertness maintaining tasks (AMTs) on driver performance, subjective feelings, and psychophysiological state in monotonous simulated driving in two experiments. In the first experiment, 12 professional truck drivers participated in five sessions of simulated driving: driving only, driving with one of three AMTs (counterbalanced), and driving while listening to music. AMTs were not equally effective in maintaining alertness. The trivia AMT prevented driving performance deterioration, and increased alertness (measured by standardized HRV). The choice reaction time AMT was least demanding but also increased subjective sleepiness and reduced arousal (measured by alpha/beta ratio). The working memory AMT caused a significant decrement in driving speed, increased subjective fatigue, and was regarded by the participants as detrimental to driving. Trivia was preferred by the majority of the drivers over the other two AMTs. Experiment 2 further examined the utility of the trivia AMT. When the drivers engaged in the trivia AMT they maintained better driving performance and perceived the driving duration as shorter than the control condition. The two experiments demonstrated that AMTs can have a positive effect on alertness. The effect is localized in the sense that it does not persist beyond the period of the AMT activation. PMID:18460351

  12. Labs drive the arms race

    SciTech Connect

    DeWitt, H.E.

    1984-11-01

    The conviction of laboratory managers that high technology can provide safety and national security in a dangerous world and that technological solutions are paramount over political solutions has been a major driving force in perpetuating the nuclear arms race. The credo in the laboratories appears to be that there are never enough designs of nuclear weapons for deterrence so that there is always a need to develop such new ideas as the nuclear-pumped X-ray laser as a defense against energy missiles. The author outlines several alternative steps, including the ratification and reaffirmation of arms control treaties, negotiations, and a halt to the Star Wars program. A central point is to stop nuclear weapons testing. 7 references.

  13. Incentives required to drive change.

    PubMed

    Corbett, Stephen

    2012-01-01

    The authors of "Chartbook: Shining a Light on the Quality of Healthcare in Canada," focus on building a Canadian healthcare performance baseline, highlighting opportunities to improve the system and then raising policy questions. This is a thoughtful approach to gaining awareness of the relative performance across the Canadian healthcare system. In essence, it is necessary to first establish a felt need, identify areas to improve and then ensure the system will implement the necessary changes to improve. The authors build a reasonable case for why improvements are necessary, and they identify key barriers that must be removed to actually realize improvements and offer a wide range of policy recommendations. However, not all of these recommendations are focused on the key point of ensuring that there are incentives in place to drive participants to implement changes. PMID:22543330

  14. Current Drive in Recombining Plasma

    SciTech Connect

    P.F. Schmit and N.J. Fisch

    2012-05-15

    The Langevin equations describing the average collisional dynamics of suprathermal particles in nonstationary plasma remarkably admit an exact analytical solution in the case of recombining plasma. The current density produced by arbitrary particle fluxes is derived including the effect of charge recombination. Since recombination has the effect of lowering the charge density of the plasma, thus reducing the charged particle collisional frequencies, the evolution of the current density can be modified substantially compared to plasma with fixed charge density. The current drive efficiency is derived and optimized for discrete and continuous pulses of current, leading to the discovery of a nonzero "residual" current density that persists indefinitely under certain conditions, a feature not present in stationary plasmas.

  15. [Stress of driving: general overview].

    PubMed

    Costa, G

    2012-01-01

    Driving is a stressful task that requires high levels of attention and vigilance to cope properly with job demands, mainly related to working hours and timetables, weather and traffic conditions, passengers and goods safety, responsibility in case of error and/or accident. Scientific literature shows a higher prevalence of cardiovascular, gastrointestinal, neuropsychic and musculoskeletal disorders, and consequent sick leaves, in professional bus/lorry and train drivers. Several studies have emphasized that stress, fatigue and excessive sleepiness give a significant contribution to occupational road and rail accidents. There are noteworthy, interindividual differences concerning alertness/sleepiness and tolerance to fatigue, related to psychophysiological and behavioural characteristics and health status, in particular: age, ability to overcome drowsiness, morningness/eveningness, diet and intake of psychotropic substances (alcohol, drugs, medicaments), primary and secondary sleep disorders (insomnia, ipersomnias, parasomnias). PMID:23213814

  16. Unsafe driving behaviors and hospitalization.

    PubMed

    Van Tuinen, M

    1994-04-01

    The medical costs associated with motor vehicle crashes are difficult to measure. Most attempts have used crash data and cost data that are only indirectly related to each other or have followed patients in a few hospitals or trauma centers. These studies produce localized estimates or rough national estimates of limited use to policy makers. The result has been a dependence on more readily available mortality data, such as the Fatal Accident Reporting System, to guide automotive safety efforts. The limitations of mortality data and the increasing sophistication of medical care data bases have resulted in a strong interest in obtaining crash-linked morbidity data. Hence, in 1993, the National Highway Traffic Safety Administration (NHTSA) awarded the Missouri Department of Health and six other applicants grants to link automotive crash records to statewide ambulance trip, outpatient care, hospitalization and mortality records. By identifying an individual across multiple data sets, states would be able to determine directly the relationship of driver behaviors and crash characteristics to hospitalization rates and other medical outcomes. Examination of hospital pay source information would expose the toll of automotive crashes on public tax dollars. Having recently completed the record linkage phase of this project, Missouri Department of Health staff are beginning to analyze the impact of automotive crashes on health care costs in Missouri. In this report, three unsafe driving behaviors, failure to use a safety device (seatbelts and motorcycle helmets), driving under the influence of alcohol, and speeding, are related to the risk of hospitalization or death, hospital costs, and expected pay source. PMID:8202067

  17. Traction Drives for Zero Stick-Slip Robots, and Reaction Free, Momentum Balanced Systems

    NASA Technical Reports Server (NTRS)

    Anderson, William J.; Shipitalo, William; Newman, Wyatt

    1995-01-01

    Balanced (Grounded Ring) Drive performed as expected kinematically. Reduction r-atios to the two counterrotating outputs (design nominal=24:1) were measured to be 23.98:1 and 24.12:1 at zero load.. At 25ONm (2200 in-lbf) output torque the ratio changed 2% due to roller creep. This drive was the smoothest of all three as determined from linearity and cogging tests, and maximum measured efficiency (ratio of power out to power in) was 95%. The disadvantages of full preloading as comvared to variable preload were apparent in this drive as in the Differential Roller Drive. Efficiencies at part load were low, but improved dramatically with increases in torque. These were consistent with friction measurements which indicated losses primarily from Coulomb friction. The initial preload level setting was low so roller slip was encountered at higher torques during testing.

  18. Error analysis of friction drive elements

    NASA Astrophysics Data System (ADS)

    Wang, Guomin; Yang, Shihai; Wang, Daxing

    2008-07-01

    Friction drive is used in some large astronomical telescopes in recent years. Comparing to the direct drive, friction drive train consists of more buildup parts. Usually, the friction drive train consists of motor-tachometer unit, coupling, reducer, driving roller, big wheel, encoder and encoder coupling. Normally, these buildup parts will introduce somewhat errors to the drive system. Some of them are random error and some of them are systematic error. For the random error, the effective way is to estimate their contributions and try to find proper way to decrease its influence. For the systematic error, the useful way is to analyse and test them quantitively, and then feedback the error to the control system to correct them. The main task of this paper is to analyse these error sources and find out their characteristics, such as random error, systematic error and contributions. The methods or equations used in the analysis will be also presented detail in this paper.

  19. Electric vehicle drive train with contactor protection

    DOEpatents

    Konrad, C.E.; Benson, R.A.

    1994-11-29

    A drive train for an electric vehicle includes a traction battery, a power drive circuit, a main contactor for connecting and disconnecting the traction battery and the power drive circuit, a voltage detector across contacts of the main contactor, and a controller for controlling the main contactor to prevent movement of its contacts to the closed position when the voltage across the contacts exceeds a predetermined threshold, to thereby protect the contacts of the contactor. The power drive circuit includes an electric traction motor and a DC-to-AC inverter with a capacitive input filter. The controller also inhibits the power drive circuit from driving the motor and thereby discharging the input capacitor if the contacts are inadvertently opened during motoring. A precharging contactor is controlled to charge the input filter capacitor prior to closing the main contactor to further protect the contacts of the main contactor. 3 figures.

  20. Electric vehicle drive train with contactor protection

    DOEpatents

    Konrad, Charles E.; Benson, Ralph A.

    1994-01-01

    A drive train for an electric vehicle includes a traction battery, a power drive circuit, a main contactor for connecting and disconnecting the traction battery and the power drive circuit, a voltage detector across contacts of the main contactor, and a controller for controlling the main contactor to prevent movement of its contacts to the closed position when the voltage across the contacts exceeds a predetermined threshold, to thereby protect the contacts of the contactor. The power drive circuit includes an electric traction motor and a DC-to-AC inverter with a capacitive input filter. The controller also inhibits the power drive circuit from driving the motor and thereby discharging the input capacitor if the contacts are inadvertently opened during motoring. A precharging contactor is controlled to charge the input filter capacitor prior to closing the main contactor to further protect the contacts of the main contactor.

  1. Application of traction drives as servo mechanisms

    NASA Technical Reports Server (NTRS)

    Loewenthal, S. H.; Rohn, D. A.; Steinetz, B. M.

    1985-01-01

    The suitability of traction drives for a wide class of aerospace control mechanisms is examined. Potential applications include antenna or solar array drive positioners, robotic joints, control moment gyro (CMG) actuators and propeller pitch change mechanisms. In these and similar applications the zero backlash, high torsional stiffness, low hysteresis and torque ripple characteristics of traction drives are of particular interest, as is the ability to run without liquid lubrication in certain cases. Wear and fatigue considerations for wet and dry operation are examined along with the tribological performance of several promising self lubricating polymers for traction contracts. The speed regulation capabilities of variable ratio traction drives are reviewed. A torsional stiffness analysis described suggests that traction contacts are relatively stiff compared to gears and are significantly stiffer than the other structural elements in the prototype CMG traction drive analyzed. Discussion is also given of an advanced turboprop propeller pitch change mechanism that incorporates a traction drive.

  2. An analysis of traction drive torsional stiffness

    NASA Technical Reports Server (NTRS)

    Rohn, D. A.; Loewenthal, S. H.

    1983-01-01

    The tangential compliance of elastic bodies in concentrated contact applied to traction drive elements to determine their torsional stiffness was analyzed. Static loading and rotating conditions are considered. The effects of several design variables are shown. The theoretical torsional stiffness of a fixed ratio multiroller drive is computed and compared to experimental values. It is shown that the torsional compliance of the traction contacts themselves is a relatively small portion of the overall drive system compliance.

  3. Driving Miss Bradley: performance measurement to support thermal driving

    NASA Astrophysics Data System (ADS)

    Piccione, Dino; Ferrett, Donald A.

    1998-07-01

    The Driver's Vision Enhancer (DVE) program is providing a system to enlarge the driving envelope for the community of military wheeled and tracked vehicles. The DVE, an IR device, provides the driver with images of the forward scene under night and adverse day conditions. During the DVE development program, several questions emerged requiring performance-based data to resolve. A comprehensive program to provide the Project Manager, Night Vision/Reconnaissance, Surveillance and Target Acquisition with driver performance data that will aid in the decision-making process is described in this paper. The program involves several linked efforts including: the relative merits of the DVE and night vision goggles (NVG); drivers' ability to detect the presence of drop-offs when using the DVE and NVG; the effect on performance of various levels of nonuniformity and nonresponsiveness in the display/sensor system; the analysis of drivers' vision using an eye-tracker in a vehicle; and the evaluation of candidate symbology to enhance the DVE's utility in the M2 Bradley. The data collected will aid in making decisions on how to write a system specification to reduce cost without sacrificing driver performance, gain an understanding of how drivers use the DVE in operational settings, and determine where training is needed to enhance safety and reduce risk on the battlefield.

  4. Women drive better if not stereotyped.

    PubMed

    Moè, Angelica; Cadinu, Mara; Maass, Anne

    2015-12-01

    A commonly held stereotype is that women are poor drivers. This stereotype is recognized and endorsed by women and girls very early on, long before taking their driving licence, nevertheless they are less involved in accidents and drive safer and less fast than men. In line with the stereotype threat theory, the present study tests the hypothesis that making the driving stereotype salient will lead women to underperform in a driving simulation task. In Experiment 1women in the stereotype threat condition were told that the aim of the study was to detect gender differences in driving whereas in a control condition no study aim was provided. In Experiment 2, two conditions were compared: stereotype threat (same instructions as in Experiment 1), and stereotype boost (the alleged goal was to compare driving ability of young vs. old people). As predicted, the results of both experiments showed that women under stereotype threat, as compared to either control or stereotype boost participants, doubled the number of mistakes. Nevertheless, they overall expected/self-reported to drive/have driven poorly. Importantly, their level of expectation was a significant predictor of their actual driving performance only in the stereotype threat condition. Implications of these effects of stereotype threat on women's driving performance and self-assessment are discussed. PMID:26457739

  5. Camshaft driving device for internal combustion engine

    SciTech Connect

    Ebesu, H.

    1988-06-14

    A camshaft driving device for use in a double overhead cam type internal combustion engine having a cylinder block, an upper deck formed at an upper portion of the cylinder block, a cylinder head disposed on the cylinder block, a driving shaft rotatably mounted at a lower portion of the cylinder block, and a pair of camshafts rotatably mounted at an upper portion of the cylinder head, is described comprising: driving force transmitting endless chain members engaging in the reduction gear means for transmitting a driving force from the driving shaft to the pair of camshaft through the reduction gear means. The camshaft driving device further including chain tensioners for tightening the chain, a nozzle means for supplying a lubricating oil to the driving force chain members on the side of the drive shaft and an oil guide wall formed immediately above the sprocket of the transmitting portion of the reduction gear means at a lower end portion of the journal boss and lapping thereover both in the radial direction and in the axial direction of the driving shaft. A mounting boss for mounting the reduction gear means thereon is formed on the upper deck of the cylinder block.

  6. Configuring NIF for direct drive experiments

    SciTech Connect

    Eimerl, D.; Rothenberg, J.; Key, M.

    1995-07-11

    The National Ignition Facility (NIF) is a proposed 1.8 MJ laser facility for carrying out experiments in inertial confinement fusion, currently designed for indirect drive experiments. The direct drive approach is being pursued at the 30 kJ Omega facility at the University of Rochester. In this paper we discuss the modifications to the NIF laser that would be required for both indirect and direct drive experiments. A primary concern is the additional cost of adding direct drive capability to the facility.

  7. Metal band drives in spacecraft mechanisms

    NASA Technical Reports Server (NTRS)

    Maus, Daryl

    1993-01-01

    Transmitting and changing the characteristics of force and stroke is a requirement in nearly all mechanisms. Examples include changing linear to rotary motion, providing a 90 deg change in direction, and amplifying stroke or force. Requirements for size, weight, efficiency and reliability create unique problems in spacecraft mechanisms. Flexible metal band and cam drive systems provide powerful solutions to these problems. Band drives, rack and pinion gears, and bell cranks are compared for effectiveness. Band drive issues are discussed including materials, bend radius, fabrication, attachment and reliability. Numerous mechanisms are shown which illustrate practical applications of band drives.

  8. Warp Drive - From Imagination to Reality

    NASA Astrophysics Data System (ADS)

    Gardiner, J.

    The realisation of warp drive is far beyond current science and technology; nevertheless, setting out a timetable for the realisation of warp drive is instructive as this will set expectations for the progress of future research. It is proposed that a time scale for the realisation of warp drive can be estimated by historical analogy with the development of manned space travel to the Moon, using conventional project estimation techniques. A timeline for space travel to the Moon begins with Cyrano de Bergerac's Voyage dans la Lune in 1657 and culminates with the Apollo 11 Moon landing in 1969, a little over 300 years later. A similar timeline for warp drive begins with John W. Campbell's novel Islands of Space in 1930. Fictional conjecture on the warp drive has given way to serious scientific speculation following publication of Alcubierre's seminal warp drive paper in 1994. It is concluded that the realisation of warp drive might be achieved around the year 2180. A projected timetable for the realisation of warp drive through phases of conjecture , speculation , science , technology and application suggests that the warp drive proposal should enter the science phase around the year 2030.

  9. The consequences of drunken driving in South Africa.

    PubMed

    Becker, K

    1994-01-01

    With the increase of alcohol use and abuse in South Africa, there has been an increase in the frequency of drunken driving offences. The community has become increasingly irate at the horrendous damage and loss of life which are occasioned by these offences. The courts have therefore been forced to take not of public opinion, and the penalties have consequently become more stringent and punitive. This article focuses primarily on the recurrent conflict between medical treatment and the imposition of punishment when the court is confronted by a person who has been driving whilst exceeding the legal blood alcohol limit. The courts are faced with having to differentiate between those persons who have an alcohol dependency and those who have merely behaved irresponsibly. What do they do? If the law deals with both cases in the same manner, it would not be achieving anything. The legal system in South Africa needs to differentiate between those persons who have an addiction and subsequently need treatment, and those who need education. The legal system needs, therefore, to make provision for proper independent professional diagnostic assessment. This article suggests alternative options which the courts could adopt in order to deal with these offences in a more flexible and effective manner. PMID:8065239

  10. Analysis of cache for streaming tape drive

    NASA Technical Reports Server (NTRS)

    Chinnaswamy, V.

    1993-01-01

    A tape subsystem consists of a controller and a tape drive. Tapes are used for backup, data interchange, and software distribution. The backup operation is addressed. During a backup operation, data is read from disk, processed in CPU, and then sent to tape. The processing speeds of a disk subsystem, CPU, and a tape subsystem are likely to be different. A powerful CPU can read data from a fast disk, process it, and supply the data to the tape subsystem at a faster rate than the tape subsystem can handle. On the other hand, a slow disk drive and a slow CPU may not be able to supply data fast enough to keep a tape drive busy all the time. The backup process may supply data to tape drive in bursts. Each burst may be followed by an idle period. Depending on the nature of the file distribution in the disk, the input stream to the tape subsystem may vary significantly during backup. To compensate for these differences and optimize the utilization of a tape subsystem, a cache or buffer is introduced in the tape controller. Most of the tape drives today are streaming tape drives. A streaming tape drive goes into reposition when there is no data from the controller. Once the drive goes into reposition, the controller can receive data, but it cannot supply data to the tape drive until the drive completes its reposition. A controller can also receive data from the host and send data to the tape drive at the same time. The relationship of cache size, host transfer rate, drive transfer rate, reposition, and ramp up times for optimal performance of the tape subsystem are investigated. Formulas developed will also show the advantages of cache watermarks to increase the streaming time of the tape drive, maximum loss due to insufficient cache, tradeoffs between cache and reposition times and the effectiveness of cache on a streaming tape drive due to idle times or interruptions due in host transfers. Several mathematical formulas are developed to predict the performance of the tape

  11. Driving DSA into volume manufacturing

    NASA Astrophysics Data System (ADS)

    Somervell, Mark; Yamauchi, Takashi; Okada, Soichiro; Tomita, Tadatoshi; Nishi, Takanori; Kawakami, Shinichiro; Muramatsu, Makoto; Iijima, Etsuo; Rastogi, Vinayak; Nakano, Takeo; Iwao, Fumiko; Nagahara, Seiji; Iwaki, Hiroyuki; Dojun, Makiko; Yatsuda, Koichi; Tobana, Toshikatsu; Romo Negreira, Ainhoa; Parnell, Doni; Rathsack, Benjamen; Nafus, Kathleen; Peyre, Jean-Luc; Kitano, Takahiro

    2015-03-01

    Directed Self-Assembly (DSA) is being extensively evaluated for application in semiconductor process integration.1-7 Since 2011, the number of publications on DSA at SPIE has exploded from roughly 26 to well over 80, indicating the groundswell of interest in the technology. Driving this interest are a number of attractive aspects of DSA including the ability to form both line/space and hole patterns at dimensions below 15 nm, the ability to achieve pitch multiplication to extend optical lithography, and the relatively low cost of the processes when compared with EUV or multiple patterning options. Tokyo Electron Limited has focused its efforts in scaling many laboratory demonstrations to 300 mm wafers. Additionally, we have recognized that the use of DSA requires specific design considerations to create robust layouts. To this end, we have discussed the development of a DSA ecosystem that will make DSA a viable technology for our industry, and we have partnered with numerous companies to aid in the development of the ecosystem. This presentation will focus on our continuing role in developing the equipment required for DSA implementation specifically discussing defectivity reduction on flows for making line-space and hole patterns, etch transfer of DSA patterns into substrates of interest, and integration of DSA processes into larger patterning schemes.

  12. Redundant arrays of IDE drives

    SciTech Connect

    D.A. Sanders et al.

    2002-01-02

    The authors report tests of redundant arrays of IDE disk drives for use in offline high energy physics data analysis. Parts costs of total systems using commodity EIDE disks are now at the $4000 per Terabyte level. Disk storage prices have now decreased to the point where they equal the cost per Terabyte of Storage Technology tape silos. The disks, however, offer far better granularity; even small institutions can afford to deploy systems. The tests include reports on software RAID-5 systems running under Linux 2.4 using Promise Ultra 100{trademark} disk controllers. RAID-5 protects data in case of a single disk failure by providing parity bits. Tape backup is not required. Journaling file systems are used to allow rapid recovery from crashes. The data analysis strategy is to encapsulate data and CPU processing power. Analysis for a particular part of a data set takes place on the PC where the data resides. The network is only used to put results together. They explore three methods of moving data between sites; internet transfers, not pluggable IDE disks in FireWire cases, and DVD-R disks.

  13. The Thermodynamics of Drunk Driving

    NASA Astrophysics Data System (ADS)

    Thompson, Robert Q.

    1997-05-01

    Chemical and instrumental tests for driving under the influence of alcohol (DUI) measure the concentration of ethanol in the breath (BrAC), while state DUI laws are described in terms of blood alcohol concentration (BAC). Consequently, accurate and fair conversion from BrAC to BAC is crucial to the judicial process. Theoretical treatment of the water-air-ethanol equilibrium system and the related blood-breath-ethanol system, based on principles from general chemistry and biology, yields an equation relating the ratio of BAC to BrAC to the absolute temperature of the breath, the fraction of water in the blood, and the enthalpy and entropy of vaporization of ethanol from aqueous solution. The model equation predicts an average value for the ratio of 2350+100, not significantly different from reported experimental values. An exponential temperature dependence is predicted and has been confirmed experimentally as well. Biological, chemical, and instrumental variables are described along with their contributions to the overall uncertainty in the value of BrAC/BAC. While the forensic science community uses, and debates, a fixed ratio of 2100, the theoretical model suggests that a value of 1880 should be used to reduce the fraction of false positives to <1%.

  14. Kinesin 1 Drives Autolysosome Tubulation.

    PubMed

    Du, Wanqing; Su, Qian Peter; Chen, Yang; Zhu, Yueyao; Jiang, Dong; Rong, Yueguang; Zhang, Senyan; Zhang, Yixiao; Ren, He; Zhang, Chuanmao; Wang, Xinquan; Gao, Ning; Wang, Yanfeng; Sun, Lingfei; Sun, Yujie; Yu, Li

    2016-05-23

    Autophagic lysosome reformation (ALR) plays an important role in maintaining lysosome homeostasis. During ALR, lysosomes are reformed by recycling lysosomal components from autolysosomes. The most noticeable step of ALR is autolysosome tubulation, but it is currently unknown how the process is regulated. Here, using an approach combining in vivo studies and in vitro reconstitution, we found that the kinesin motor protein KIF5B is required for autolysosome tubulation and that KIF5B drives autolysosome tubulation by pulling on the autolysosomal membrane. Furthermore, we show that KIF5B directly interacts with PtdIns(4,5)P2. Kinesin motors are recruited and clustered on autolysosomes via interaction with PtdIns(4,5)P2 in a clathrin-dependent manner. Finally, we demonstrate that clathrin promotes formation of PtdIns(4,5)P2-enriched microdomains, which are required for clustering of KIF5B. Our study reveals a mechanism by which autolysosome tubulation was generated. PMID:27219061

  15. What drives polymer glasses ductile?

    NASA Astrophysics Data System (ADS)

    Wang, Shi-Qing; Cheng, Shiwang; Li, Xiaoxiao; Lin, Panpan; Liu, Jianning

    2015-03-01

    The presentation aims to explore an important question in polymer physics: what makes polymer glasses of high molecular weight ductile? Upon deformation, load-bearing strands (LBS) emerge along the direction of the stress. Chain tension builds up in LBS due to the displacement of LBS. Segments that do not belong to LBS sequentially get activated by the LBS in the order of their proximity to LBS. If the chain network breaks down before driving the glass into a state of global plasticity, crazing and brittle fracture takes place instead of yielding and macroscopic plastic deformation. Fast deformation assures that chain pullout does not have time to materialize. Global plasticity also takes time to develop. Thus, the outcome is dictated by which process takes place first. In light of the recently proposed molecular model for yielding and brittle-ductile transition of polymer glasses, we present different examples from experiment to illustrate the importance to understand the interplay between short-ranged intersegmental interactions and long-ranged intrachain networking. NSF-DMR (EAGER- 1444859)

  16. Variable frequency drive applications guide

    SciTech Connect

    Laloudakis, D.J.

    1991-10-01

    Traditionally, fans and pumps have been designed to be capable of handling the maximum demand of the system in which they are installed. However, quite often the actual demand can vary and it can be much lower than the original design capacity. These situations have been corrected in the past through additions of outlet dampers to fans or throttling valves to pumps. While these can be effective and simple controls they severely affect the efficiency of the system. Variable frequency (speed) is the most efficient means of capacity control. The most cost effective method of achieving variable speed capacity control is using AC adjustable frequency drives. AC adjustable frequency controls convert any fixed speed AC motor into an adjustable speed device. Adjusting the speed of a motor, by controlling the frequency of the AC power to that motor, reduces its horsepower requirements. According to pump and fan laws, capacity is proportional to speed while horsepower is proportional to the cube of the speed. Therefore, by reducing the speed of an AC motor by 20 percent the horsepower requirement is reduced by nearly 50 percent. Reduced speed through variable frequency control allows for flexibility of meeting changing weather and comfort requirements without operating costly equipment at full capacity.

  17. Control rod drive hydraulic system

    DOEpatents

    Ose, Richard A.

    1992-01-01

    A hydraulic system for a control rod drive (CRD) includes a variable output-pressure CR pump operable in a charging mode for providing pressurized fluid at a charging pressure, and in a normal mode for providing the pressurized fluid at a purge pressure, less than the charging pressure. Charging and purge lines are disposed in parallel flow between the CRD pump and the CRD. A hydraulic control unit is disposed in flow communication in the charging line and includes a scram accumulator. An isolation valve is provided in the charging line between the CRD pump and the scram accumulator. A controller is operatively connected to the CRD pump and the isolation valve and is effective for opening the isolation valve and operating the CRD pump in a charging mode for charging the scram accumulator, and closing the isolation valve and operating the CRD pump in a normal mode for providing to the CRD through the purge line the pressurized fluid at a purge pressure lower than the charging pressure.

  18. 77 FR 61048 - Distracted Driving Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-05

    ... grant program, 77 FR 51610 (Aug. 24, 2012), which established an application deadline of October 9, 2012... National Highway Traffic Safety Administration Distracted Driving Grant Program AGENCY: National Highway... Transportation (DOT) announced the availability of funding authorized for distracted driving grants on August...

  19. Mechanical vs electric drive: which to choose

    SciTech Connect

    Smiley, C.H.

    1983-03-01

    In the highly competitive 85 to 120 ton haul truck market, mechanical drive units have become increasingly popular because of their lower initial investment costs. But when total ownership costs over the life of the vehicle are considered, electric drive remains highly competitive.

  20. Steady State Tokamak Equilibria without Current Drive

    SciTech Connect

    Shaing, K.C.; Aydemir, A.Y.; Lin-Liu, Y.R.; Miller, R.L.

    1997-11-01

    Steady state tokamak equilibria without current drive are found. This is made possible by including the potato bootstrap current close to the magnetic axis. Tokamaks with this class of equilibria do not need seed current or current drive, and are intrinsically steady state. {copyright} {ital 1997} {ital The American Physical Society}