Modeling bivalve diversification: the effect of interaction on a macroevolutionary system

NASA Technical Reports Server (NTRS)

Miller, A. I.; Sepkoski, J. J. Jr; Sepkoski JJ, J. r. (Principal Investigator)

1988-01-01

The global diversification of the class Bivalvia has historically received two conflicting interpretations. One is that a major upturn in diversification was associated with, and a consequence of, the Lake Permian mass extinction. The other is that mass extinctions have had little influence and that bivalves have experienced slow but nearly steady exponential diversification through most of their history, unaffected by interactions with other clades. We find that the most likely explanation lies between these two interpretations. Through most of the Phanerozoic, the diversity of bivalves did indeed exhibit slow growth, which was not substantially altered by mass extinctions. However, the presence of "hyperexponential bursts" in diversification during the initial Ordovician radiation and following the Late Permian and Late Cretaceous mass extinctions suggests a more complex history in which a higher characteristic diversification rate was dampened through most of the Phanerozoic. The observed pattern can be accounted for with a two-phase coupled (i.e., interactive) logistic model, where one phase is treated as the "bivalves" and the other phase is treated as a hypothetical group of clades with which the "bivalves" might have interacted. Results of this analysis suggest that interactions with other taxa have substantially affected bivalve global diversity through the Phanerozoic.

Adaptation of Mycobacterium smegmatis to Stationary Phase

PubMed Central

Smeulders, Marjan J.; Keer, Jacquie; Speight, Richard A.; Williams, Huw D.

1999-01-01

Mycobacterium tuberculosis can persist for many years within host lung tissue without causing clinical disease. Little is known about the state in which the bacilli survive, although it is frequently referred to as dormancy. Some evidence suggests that cells survive in nutrient-deprived stationary phase. Therefore, we are studying stationary-phase survival of Mycobacterium smegmatis as a model for mycobacterial persistence. M. smegmatis cultures could survive 650 days of either carbon, nitrogen, or phosphorus starvation. In carbon-limited medium, cells entered stationary phase before the carbon source (glycerol) had been completely depleted and glycerol uptake from the medium continued during the early stages of stationary phase. These results suggest that the cells are able to sense when the glycerol is approaching limiting concentrations and initiate a shutdown into stationary phase, which involves the uptake of the remaining glycerol from the medium. During early stationary phase, cells underwent reductive cell division and became more resistant to osmotic and acid stress and pool mRNA stabilized. Stationary-phase cells were also more resistant to oxidative stress, but this resistance was induced during late exponential phase in a cell-density-dependent manner. Upon recovery in fresh medium, stationary-phase cultures showed an immediate increase in protein synthesis irrespective of culture age. Colony morphology variants accumulated in stationary-phase cultures. A flat colony variant was seen in 75% of all long-term-stationary-phase cultures and frequently took over the whole population. Cryo scanning electron microscopy showed that the colony organization was different in flat colony strains, flat colonies appearing less well organized than wild-type colonies. Competition experiments with an exponential-phase-adapted wild-type strain showed that the flat strain had a competitive advantage in stationary phase, as well a providing evidence that growth and cell division occur in stationary-phase cultures of M. smegmatis. These results argue against stationary-phase M. smegmatis cultures entering a quiescent state akin to dormancy but support the idea that they are a dynamic population of cells. PMID:9864340

Theory for Transitions Between Exponential and Stationary Phases: Universal Laws for Lag Time

NASA Astrophysics Data System (ADS)

Himeoka, Yusuke; Kaneko, Kunihiko

2017-04-01

The quantitative characterization of bacterial growth has attracted substantial attention since Monod's pioneering study. Theoretical and experimental works have uncovered several laws for describing the exponential growth phase, in which the number of cells grows exponentially. However, microorganism growth also exhibits lag, stationary, and death phases under starvation conditions, in which cell growth is highly suppressed, for which quantitative laws or theories are markedly underdeveloped. In fact, the models commonly adopted for the exponential phase that consist of autocatalytic chemical components, including ribosomes, can only show exponential growth or decay in a population; thus, phases that halt growth are not realized. Here, we propose a simple, coarse-grained cell model that includes an extra class of macromolecular components in addition to the autocatalytic active components that facilitate cellular growth. These extra components form a complex with the active components to inhibit the catalytic process. Depending on the nutrient condition, the model exhibits typical transitions among the lag, exponential, stationary, and death phases. Furthermore, the lag time needed for growth recovery after starvation follows the square root of the starvation time and is inversely related to the maximal growth rate. This is in agreement with experimental observations, in which the length of time of cell starvation is memorized in the slow accumulation of molecules. Moreover, the lag time distributed among cells is skewed with a long time tail. If the starvation time is longer, an exponential tail appears, which is also consistent with experimental data. Our theory further predicts a strong dependence of lag time on the speed of substrate depletion, which can be tested experimentally. The present model and theoretical analysis provide universal growth laws beyond the exponential phase, offering insight into how cells halt growth without entering the death phase.

Fundamental Flux Equations for Fracture-Matrix Interactions with Linear Diffusion

NASA Astrophysics Data System (ADS)

Oldenburg, C. M.; Zhou, Q.; Rutqvist, J.; Birkholzer, J. T.

2017-12-01

The conventional dual-continuum models are only applicable for late-time behavior of pressure propagation in fractured rock, while discrete-fracture-network models may explicitly deal with matrix blocks at high computational expense. To address these issues, we developed a unified-form diffusive flux equation for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular matrix blocks (squares, cubes, rectangles, and rectangular parallelepipeds) by partitioning the entire dimensionless-time domain (Zhou et al., 2017a, b). For each matrix block, this flux equation consists of the early-time solution up until a switch-over time after which the late-time solution is applied to create continuity from early to late time. The early-time solutions are based on three-term polynomial functions in terms of square root of dimensionless time, with the coefficients dependent on dimensionless area-to-volume ratio and aspect ratios for rectangular blocks. For the late-time solutions, one exponential term is needed for isotropic blocks, while a few additional exponential terms are needed for highly anisotropic blocks. The time-partitioning method was also used for calculating pressure/concentration/temperature distribution within a matrix block. The approximate solution contains an error-function solution for early times and an exponential solution for late times, with relative errors less than 0.003. These solutions form the kernel of multirate and multidimensional hydraulic, solute and thermal diffusion in fractured reservoirs.

MreB-Dependent Inhibition of Cell Elongation during the Escape from Competence in Bacillus subtilis

PubMed Central

Mirouze, Nicolas; Ferret, Cécile; Yao, Zhizhong; Chastanet, Arnaud; Carballido-López, Rut

2015-01-01

During bacterial exponential growth, the morphogenetic actin-like MreB proteins form membrane-associated assemblies that move processively following trajectories perpendicular to the long axis of the cell. Such MreB structures are thought to scaffold and restrict the movement of peptidoglycan synthesizing machineries, thereby coordinating sidewall elongation. In Bacillus subtilis, this function is performed by the redundant action of three MreB isoforms, namely MreB, Mbl and MreBH. mreB and mbl are highly transcribed from vegetative promoters. We have found that their expression is maximal at the end of exponential phase, and rapidly decreases to a low basal level upon entering stationary phase. However, in cells developing genetic competence, a stationary phase physiological adaptation, expression of mreB was specifically reactivated by the central competence regulator ComK. In competent cells, MreB was found in complex with several competence proteins by in vitro pull-down assays. In addition, it co-localized with the polar clusters formed by the late competence peripheral protein ComGA, in a ComGA-dependent manner. ComGA has been shown to be essential for the inhibition of cell elongation characteristic of cells escaping the competence state. We show here that the pathway controlling this elongation inhibition also involves MreB. Our findings suggest that ComGA sequesters MreB to prevent cell elongation and therefore the escape from competence. PMID:26091431

MreB-Dependent Inhibition of Cell Elongation during the Escape from Competence in Bacillus subtilis.

PubMed

Mirouze, Nicolas; Ferret, Cécile; Yao, Zhizhong; Chastanet, Arnaud; Carballido-López, Rut

2015-06-01

During bacterial exponential growth, the morphogenetic actin-like MreB proteins form membrane-associated assemblies that move processively following trajectories perpendicular to the long axis of the cell. Such MreB structures are thought to scaffold and restrict the movement of peptidoglycan synthesizing machineries, thereby coordinating sidewall elongation. In Bacillus subtilis, this function is performed by the redundant action of three MreB isoforms, namely MreB, Mbl and MreBH. mreB and mbl are highly transcribed from vegetative promoters. We have found that their expression is maximal at the end of exponential phase, and rapidly decreases to a low basal level upon entering stationary phase. However, in cells developing genetic competence, a stationary phase physiological adaptation, expression of mreB was specifically reactivated by the central competence regulator ComK. In competent cells, MreB was found in complex with several competence proteins by in vitro pull-down assays. In addition, it co-localized with the polar clusters formed by the late competence peripheral protein ComGA, in a ComGA-dependent manner. ComGA has been shown to be essential for the inhibition of cell elongation characteristic of cells escaping the competence state. We show here that the pathway controlling this elongation inhibition also involves MreB. Our findings suggest that ComGA sequesters MreB to prevent cell elongation and therefore the escape from competence.

Enhanced astaxanthin production from Haematococcus pluvialis using butylated hydroxyanisole.

PubMed

Shang, Minmin; Ding, Wei; Zhao, Yongteng; Xu, Jun-Wei; Zhao, Peng; Li, Tao; Ma, Huixian; Yu, Xuya

2016-10-20

Haematococcus pluvialis is a promising natural source of high-value antioxidant astaxanthin under stress conditions. Biotic or abiotic elicitors are effective strategies for improving astaxanthin production in H. pluvialis. Butylated hydroxyanisole (BHA) was identified as an effective inducer for H. pluvialis LUGU. Under a treatment of 2mgL(-1) BHA (BHA2), astaxanthin content reached a maximum of 29.03mgg(-1) dry weight (DW) (2.03-fold of that in the control) after 12day of the mid-exponential growth phase. Subsequently, H. pluvialis LUGU was subjected to BHA2 at different growth phases because an appropriate time node for adding elicitors is vital for the entire production to succeed. As a result, the highest astaxanthin content (29.3mgg(-1) DW) was obtained in cells on day 14 (BHA2 14) of the late-exponential growth phase. Furthermore, the samples treated with BHA2 14 and the control group were compared in terms of the transcriptional expression of seven carotenogenesis genes, fatty acid composition, and total accumulated astaxanthin. All selected genes exhibited up-regulated expression profiles, with chy, crtO, and bkt exhibiting higher maximum transcriptional levels than the rest. Oleic acid content increased 33.15-fold, with acp, fad, and kas expression being enhanced on the day when astaxanthin was produced rapidly. Copyright © 2016 Elsevier B.V. All rights reserved.

Reduced Heme Levels Underlie the Exponential Growth Defect of the Shewanella oneidensis hfq Mutant

PubMed Central

Mezoian, Taylor; Hunt, Taylor M.; Keane, Meaghan L.; Leonard, Jessica N.; Scola, Shelby E.; Beer, Emma N.; Perdue, Sarah; Pellock, Brett J.

2014-01-01

The RNA chaperone Hfq fulfills important roles in small regulatory RNA (sRNA) function in many bacteria. Loss of Hfq in the dissimilatory metal reducing bacterium Shewanella oneidensis strain MR-1 results in slow exponential phase growth and a reduced terminal cell density at stationary phase. We have found that the exponential phase growth defect of the hfq mutant in LB is the result of reduced heme levels. Both heme levels and exponential phase growth of the hfq mutant can be completely restored by supplementing LB medium with 5-aminolevulinic acid (5-ALA), the first committed intermediate synthesized during heme synthesis. Increasing expression of gtrA, which encodes the enzyme that catalyzes the first step in heme biosynthesis, also restores heme levels and exponential phase growth of the hfq mutant. Taken together, our data indicate that reduced heme levels are responsible for the exponential growth defect of the S. oneidensis hfq mutant in LB medium and suggest that the S. oneidensis hfq mutant is deficient in heme production at the 5-ALA synthesis step. PMID:25356668

Quantitative Interaction Effects of Carbon Dioxide, Sodium Chloride, and Sodium Nitrite on Neurotoxin Gene Expression in Nonproteolytic Clostridium botulinum Type B

PubMed Central

Lövenklev, Maria; Artin, Ingrid; Hagberg, Oskar; Borch, Elisabeth; Holst, Elisabet; Rådström, Peter

2004-01-01

The effects of carbon dioxide, sodium chloride, and sodium nitrite on type B botulinum neurotoxin (BoNT/B) gene (cntB) expression in nonproteolytic Clostridium botulinum were investigated in a tryptone-peptone-yeast extract (TPY) medium. Various concentrations of these selected food preservatives were studied by using a complete factorial design in order to quantitatively study interaction effects, as well as main effects, on the following responses: lag phase duration (LPD), growth rate, relative cntB expression, and extracellular BoNT/B production. Multiple linear regression was used to set up six statistical models to quantify and predict these responses. All combinations of NaCl and NaNO2 in the growth medium resulted in a prolonged lag phase duration and in a reduction in the specific growth rate. In contrast, the relative BoNT/B gene expression was unchanged, as determined by the cntB-specific quantitative reverse transcription-PCR method. This was confirmed when we measured the extracellular BoNT/B concentration by an enzyme-linked immunosorbent assay. CO2 was found to have a major effect on gene expression when the cntB mRNA levels were monitored in the mid-exponential, late exponential, and late stationary growth phases. The expression of cntB relative to the expression of the 16S rRNA gene was stimulated by an elevated CO2 concentration; the cntB mRNA level was fivefold greater in a 70% CO2 atmosphere than in a 10% CO2 atmosphere. These findings were also confirmed when we analyzed the extracellular BoNT/B concentration; we found that the concentrations were 27 ng · ml−1 · unit of optical density−1 in the 10% CO2 atmosphere and 126 ng · ml−1 · unit of optical density−1 in the 70% CO2 atmosphere. PMID:15128553

Kinetics of force recovery following length changes in active skinned single fibres from rabbit psoas muscle

PubMed Central

Burton, Kevin; Simmons, Robert M; Sleep, John; Smith, David A

2006-01-01

Redevelopment of isometric force following shortening of skeletal muscle is thought to result from a redistribution of cross-bridge states. We varied the initial force and cross-bridge distribution by applying various length-change protocols to active skinned single fibres from rabbit psoas muscle, and observed the effect on the slowest phase of recovery (‘late recovery’) that follows transient changes. In response to step releases that reduced force to near zero (∼8 nm (half sarcomere)−1) or prolonged shortening at high velocity, late recovery was well described by two exponentials of approximately equal amplitude and rate constants of ∼2 s−1 and ∼9 s−1 at 5°C. When a large restretch was applied at the end of rapid shortening, recovery was accelerated by (1) the introduction of a slow falling component that truncated the rise in force, and (2) a relative increase in the contribution of the fast exponential component. The rate of the slow fall was similar to that observed after a small isometric step stretch, with a rate of 0.4–0.8 s−1, and its effects could be reversed by reducing force to near zero immediately after the stretch. Force at the start of late recovery was varied in a series of shortening steps or ramps in order to probe the effect of cross-bridge strain on force redevelopment. The rate constants of the two components fell by 40–50% as initial force was raised to 75–80% of steady isometric force. As initial force increased, the relative contribution of the fast component decreased, and this was associated with a length constant of about 2 nm. The results are consistent with a two-state strain-dependent cross-bridge model. In the model there is a continuous distribution of recovery rate constants, but two-exponential fits show that the fast component results from cross-bridges initially at moderate positive strain and the slow component from cross-bridges at high positive strain. PMID:16497718

Holographic insulator/superconductor transition with exponential nonlinear electrodynamics probed by entanglement entropy

NASA Astrophysics Data System (ADS)

Yao, Weiping; Yang, Chaohui; Jing, Jiliang

2018-05-01

From the viewpoint of holography, we study the behaviors of the entanglement entropy in insulator/superconductor transition with exponential nonlinear electrodynamics (ENE). We find that the entanglement entropy is a good probe to the properties of the holographic phase transition. Both in the half space and the belt space, the non-monotonic behavior of the entanglement entropy in superconducting phase versus the chemical potential is general in this model. Furthermore, the behavior of the entanglement entropy for the strip geometry shows that the confinement/deconfinement phase transition appears in both insulator and superconductor phases. And the critical width of the confinement/deconfinement phase transition depends on the chemical potential and the exponential coupling term. More interestingly, the behaviors of the entanglement entropy in their corresponding insulator phases are independent of the exponential coupling factor but depends on the width of the subsystem A.

Strand specific RNA-sequencing and membrane lipid profiling reveals growth phase-dependent cold stress response mechanisms in Listeria monocytogenes

PubMed Central

Hingston, Patricia; Chen, Jessica; Allen, Kevin; Truelstrup Hansen, Lisbeth

2017-01-01

The human pathogen Listeria monocytogenes continues to pose a challenge in the food industry, where it is known to contaminate ready-to-eat foods and grow during refrigerated storage. Increased knowledge of the cold-stress response of this pathogen will enhance the ability to control it in the food-supply-chain. This study utilized strand-specific RNA sequencing and whole cell fatty acid (FA) profiling to characterize the bacterium’s cold stress response. RNA and FAs were extracted from a cold-tolerant strain at five time points between early lag phase and late stationary-phase, both at 4°C and 20°C. Overall, more genes (1.3×) were suppressed than induced at 4°C. Late stationary-phase cells exhibited the greatest number (n = 1,431) and magnitude (>1,000-fold) of differentially expressed genes (>2-fold, p<0.05) in response to cold. A core set of 22 genes was upregulated at all growth phases, including nine genes required for branched-chain fatty acid (BCFA) synthesis, the osmolyte transporter genes opuCBCD, and the internalin A and D genes. Genes suppressed at 4°C were largely associated with cobalamin (B12) biosynthesis or the production/export of cell wall components. Antisense transcription accounted for up to 1.6% of total mapped reads with higher levels (2.5×) observed at 4°C than 20°C. The greatest number of upregulated antisense transcripts at 4°C occurred in early lag phase, however, at both temperatures, antisense expression levels were highest in late stationary-phase cells. Cold-induced FA membrane changes included a 15% increase in the proportion of BCFAs and a 15% transient increase in unsaturated FAs between lag and exponential phase. These increases probably reduced the membrane phase transition temperature until optimal levels of BCFAs could be produced. Collectively, this research provides new information regarding cold-induced membrane composition changes in L. monocytogenes, the growth-phase dependency of its cold-stress regulon, and the active roles of antisense transcripts in regulating its cold stress response. PMID:28662112

Strand specific RNA-sequencing and membrane lipid profiling reveals growth phase-dependent cold stress response mechanisms in Listeria monocytogenes.

PubMed

Hingston, Patricia; Chen, Jessica; Allen, Kevin; Truelstrup Hansen, Lisbeth; Wang, Siyun

2017-01-01

The human pathogen Listeria monocytogenes continues to pose a challenge in the food industry, where it is known to contaminate ready-to-eat foods and grow during refrigerated storage. Increased knowledge of the cold-stress response of this pathogen will enhance the ability to control it in the food-supply-chain. This study utilized strand-specific RNA sequencing and whole cell fatty acid (FA) profiling to characterize the bacterium's cold stress response. RNA and FAs were extracted from a cold-tolerant strain at five time points between early lag phase and late stationary-phase, both at 4°C and 20°C. Overall, more genes (1.3×) were suppressed than induced at 4°C. Late stationary-phase cells exhibited the greatest number (n = 1,431) and magnitude (>1,000-fold) of differentially expressed genes (>2-fold, p<0.05) in response to cold. A core set of 22 genes was upregulated at all growth phases, including nine genes required for branched-chain fatty acid (BCFA) synthesis, the osmolyte transporter genes opuCBCD, and the internalin A and D genes. Genes suppressed at 4°C were largely associated with cobalamin (B12) biosynthesis or the production/export of cell wall components. Antisense transcription accounted for up to 1.6% of total mapped reads with higher levels (2.5×) observed at 4°C than 20°C. The greatest number of upregulated antisense transcripts at 4°C occurred in early lag phase, however, at both temperatures, antisense expression levels were highest in late stationary-phase cells. Cold-induced FA membrane changes included a 15% increase in the proportion of BCFAs and a 15% transient increase in unsaturated FAs between lag and exponential phase. These increases probably reduced the membrane phase transition temperature until optimal levels of BCFAs could be produced. Collectively, this research provides new information regarding cold-induced membrane composition changes in L. monocytogenes, the growth-phase dependency of its cold-stress regulon, and the active roles of antisense transcripts in regulating its cold stress response.

Necroptotic debris including damaged mitochondria elicits sepsis-like syndrome during late-phase tularemia.

PubMed

Singh, Anju; Periasamy, Sivakumar; Malik, Meenakshi; Bakshi, Chandra Shekhar; Stephen, Laurie; Ault, Jeffrey G; Mannella, Carmen A; Sellati, Timothy J

2017-01-01

Infection with Francisella tularensis ssp. tularensis ( Ft ) strain SchuS4 causes an often lethal disease known as tularemia in rodents, non-human primates, and humans. Ft subverts host cell death programs to facilitate their exponential replication within macrophages and other cell types during early respiratory infection (⩽72 h). The mechanism(s) by which cell death is triggered remains incompletely defined, as does the impact of Ft on mitochondria, the host cell's organellar 'canary in a coal mine'. Herein, we reveal that Ft infection of host cells, particularly macrophages and polymorphonuclear leukocytes, drives necroptosis via a receptor-interacting protein kinase 1/3-mediated mechanism. During necroptosis mitochondria and other organelles become damaged. Ft -induced mitochondrial damage is characterized by: (i) a decrease in membrane potential and consequent mitochondrial oncosis or swelling, (ii) increased generation of superoxide radicals, and (iii) release of intact or damaged mitochondria into the lung parenchyma. Host cell recognition of and response to released mitochondria and other damage-associated molecular patterns engenders a sepsis-like syndrome typified by production of TNF, IL-1 β , IL-6, IL-12p70, and IFN- γ during late-phase tularemia (⩾72 h), but are absent early during infection.

Ascending-ramp biphasic waveform has a lower defibrillation threshold and releases less troponin I than a truncated exponential biphasic waveform.

PubMed

Huang, Jian; Walcott, Gregory P; Ruse, Richard B; Bohanan, Scott J; Killingsworth, Cheryl R; Ideker, Raymond E

2012-09-11

We tested the hypothesis that the shape of the shock waveform affects not only the defibrillation threshold but also the amount of cardiac damage. Defibrillation thresholds were determined for 11 waveforms-3 ascending-ramp waveforms, 3 descending-ramp waveforms, 3 rectilinear first-phase biphasic waveforms, a Gurvich waveform, and a truncated exponential biphasic waveform-in 6 pigs with electrodes in the right ventricular apex and superior vena cava. The ascending, descending, and rectilinear waveforms had 4-, 8-, and 16-millisecond first phases and a 3.5-millisecond rectilinear second phase that was half the voltage of the first phase. The exponential biphasic waveform had a 60% first-phase and a 50% second-phase tilt. In a second study, we attempted to defibrillate after 10 seconds of ventricular fibrillation with a single ≈30-J shock (6 pigs successfully defibrillated with 8-millisecond ascending, 8-millisecond rectilinear, and truncated exponential biphasic waveforms). Troponin I blood levels were determined before and 2 to 10 hours after the shock. The lowest-energy defibrillation threshold was for the 8-milliseconds ascending ramp (14.6±7.3 J [mean±SD]), which was significantly less than for the truncated exponential (19.6±6.3 J). Six hours after shock, troponin I was significantly less for the ascending-ramp waveform (0.80±0.54 ng/mL) than for the truncated exponential (1.92±0.47 ng/mL) or the rectilinear waveform (1.17±0.45 ng/mL). The ascending ramp has a significantly lower defibrillation threshold and at ≈30 J causes 58% less troponin I release than the truncated exponential biphasic shock. Therefore, the shock waveform affects both the defibrillation threshold and the amount of cardiac damage.

Effect of benzalkonium chloride on viability and energy metabolism in exponential- and stationary-growth-phase cells of Listeria monocytogenes.

PubMed

Luppens, S B; Abee, T; Oosterom, J

2001-04-01

The difference in killing exponential- and stationary-phase cells of Listeria monocytogenes by benzalkonium chloride (BAC) was investigated by plate counting and linked to relevant bioenergetic parameters. At a low concentration of BAC (8 mg liter(-1)), a similar reduction in viable cell numbers was observed for stationary-phase cells and exponential-phase cells (an approximately 0.22-log unit reduction), although their membrane potential and pH gradient were dissipated. However, at higher concentrations of BAC, exponential-phase cells were more susceptible than stationary-phase cells. At 25 mg liter(-1), the difference in survival on plates was more than 3 log units. For both types of cells, killing, i.e., more than 1-log unit reduction in survival on plates, coincided with complete inhibition of acidification and respiration and total depletion of ATP pools. Killing efficiency was not influenced by the presence of glucose, brain heart infusion medium, or oxygen. Our results suggest that growth phase is one of the major factors that determine the susceptibility of L. monocytogenes to BAC.

Sexual reproduction as a response to H sub 2 O sub 2 damage in Schizosaccharomyces pombe

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

Bernstein, C.; Johns, V.

1989-04-01

Although sexual reproduction is widespread, its adaptive advantage over asexual reproduction is unclear. One major advantage of sex may be its promotion of recombinational repair of DNA damage during meiosis. This idea predicts that treatment of the asexual form of a facultatively sexual-asexual eucaryote with a DNA-damaging agent may cause it to enter the sexual cycle more frequently. Endogenous hydrogen peroxide is a major natural source of DNA damage. Thus, the authors treated vegetative cells of Schizosaccharomyces pombe with hydrogen peroxide to test if sexual reproduction increases. Among untreated stationary-phase S. pombe populations the sexual spores produced by meiosis representedmore » about 1% of the total cells. However, treatment of late-exponential-phase vegetative cells with hydrogen peroxide increased the percentage of meiotic spores in the stationary phase by 4- to 18-fold. Oxidative damage therefore induces sexual reproduction in a facultatively sexual organism, a result expected by the hypothesis that sex promotes DNA repair.« less

Time-course proteomics dataset to monitor protein-bound methionine oxidation in Bacillus cereus ATCC 14579.

PubMed

Madeira, Jean-Paul; Alpha-Bazin, Béatrice; Armengaud, Jean; Duport, Catherine

2018-06-01

Aerobic respiratory growth generates endogenous reactive oxygen species (ROS). ROS oxidize protein-bound methionine residues into methionine sulfoxide. Methionine sulfoxide reductases catalyze the reduction of methionine sulfoxide to methionine in proteins. Here, we use high-throughput nanoLC-MS/MS methodology to establish detailed maps of oxidized proteins from Bacillus cereus ATCC 14579 ΔpBClin15 and its mutant for which the methionine sulfoxide reductase AB gene ( msrAB ) has been inactivated (Madeira et al., 2017) [1]. Lists of oxidized peptides and proteins identified at early exponential, late exponential and stationary growth phases are supplied in this article as data files. Raw data are deposited at the ProteomeXchange Consortium via the PRIDE partner repository with the dataset identifiers, PXD006169 and PDX006205 (http://www.ebi.ac/uk). Given the importance of methionine oxidation in several key cellular processes and its impact in the field of medical and food microbiology, this paper should be useful for further insightful redox studies in B. cereus and its numerous relatives.

Shotgun proteomic monitoring of Clostridium acetobutylicum during stationary phase of butanol fermentation using xylose and comparison with the exponential phase

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

Sivagnanam, Kumaran; Raghavan, Vijaya G. S.; Shah, Manesh B

2012-01-01

Economically viable production of solvents through acetone butanol ethanol (ABE) fermentation requires a detailed understanding of Clostridium acetobutylicum. This study focuses on the proteomic profiling of C. acetobutylicum ATCC 824 from the stationary phase of ABE fermentation using xylose and compares with the exponential growth by shotgun proteomics approach. Comparative proteomic analysis revealed 22.9% of the C. acetobutylicum genome and 18.6% was found to be common in both exponential and stationary phases. The proteomic profile of C. acetobutylicum changed during the ABE fermentation such that 17 proteins were significantly differentially expressed between the two phases. Specifically, the expression of fivemore » proteins namely, CAC2873, CAP0164, CAP0165, CAC3298, and CAC1742 involved in the solvent production pathway were found to be significantly lower in the stationary phase compared to the exponential growth. Similarly, the expression of fucose isomerase (CAC2610), xylulose kinase (CAC2612), and a putative uncharacterized protein (CAC2611) involved in the xylose utilization pathway were also significantly lower in the stationary phase. These findings provide an insight into the metabolic behavior of C. acetobutylicum between different phases of ABE fermentation using xylose.« less

Transcriptome analysis reveals a stress response of Shewanella oneidensis deprived of background levels of ionizing radiation

PubMed Central

Li, Xiaoping; Schilkey, Faye; Smith, Geoffrey B.

2018-01-01

Natural ionizing background radiation has exerted a constant pressure on organisms since the first forms of life appeared on Earth, so that cells have developed molecular mechanisms to avoid or repair damages caused directly by radiation or indirectly by radiation-induced reactive oxygen species (ROS). In the present study, we investigated the transcriptional effect of depriving Shewanella oneidensis cultures of background levels of radiation by growing the cells in a mine 655 m underground, thus reducing the dose rate from 72.1 to 0.9 nGy h-1 from control to treatment, respectively. RNASeq transcriptome analysis showed the differential expression of 4.6 and 7.6% of the S. oneidensis genome during early- and late-exponential phases of growth, respectively. The greatest change observed in the treatment was the downregulation of ribosomal proteins (21% of all annotated ribosomal protein genes during early- and 14% during late-exponential) and tRNA genes (14% of all annotated tRNA genes in early-exponential), indicating a marked decrease in protein translation. Other significant changes were the upregulation of membrane transporters, implying an increase in the traffic of substrates across the cell membrane, as well as the up and downregulation of genes related to respiration, which could be interpreted as a response to insufficient oxidants in the cells. In other reports, there is evidence in multiple species that some ROS not just lead to oxidative stress, but act as signaling molecules to control cellular metabolism at the transcriptional level. Consistent with these reports, several genes involved in the metabolism of carbon and biosynthesis of amino acids were also regulated, lending support to the idea of a wide metabolic response. Our results indicate that S. oneidensis is sensitive to the withdrawal of background levels of ionizing radiation and suggest that a transcriptional response is required to maintain homeostasis and retain normal growth. PMID:29768440

Cosmological solutions and finite time singularities in Finslerian geometry

NASA Astrophysics Data System (ADS)

Paul, Nupur; de, S. S.; Rahaman, Farook

2018-03-01

We consider a very general scenario of our universe where its geometry is characterized by the Finslerian structure on the underlying spacetime manifold, a generalization of the Riemannian geometry. Now considering a general energy-momentum tensor for matter sector, we derive the gravitational field equations in such spacetime. Further, to depict the cosmological dynamics in such spacetime proposing an interesting equation of state identified by a sole parameter γ which for isotropic limit is simply the barotropic equation of state p = (γ ‑ 1)ρ (γ ∈ ℝ being the barotropic index), we solve the background dynamics. The dynamics offers several possibilities depending on this sole parameter as follows: (i) only an exponential expansion, or (ii) a finite time past singularity (big bang) with late accelerating phase, or (iii) a nonsingular universe exhibiting an accelerating scenario at late time which finally predicts a big rip type singularity. We also discuss several energy conditions and the possibility of cosmic bounce. Finally, we establish the first law of thermodynamics in such spacetime.

Ectoine and 5-hydroxyectoine accumulation in the halophile Virgibacillus halodenitrificans PDB-F2 in response to salt stress.

PubMed

Tao, Ping; Li, Hui; Yu, Yunjiang; Gu, Jidong; Liu, Yongdi

2016-08-01

The moderately halophilic bacterium Virgibacillus halodenitrificans PDB-F2 copes with salinity by synthesizing or taking up compatible solutes. The main compatible solutes in this strain were ectoine and hydroxyectoine, as determined by (1)H nuclear magnetic resonance spectroscopy ((1)H-NMR). A high-performance liquid chromatography (HPLC) analysis showed that ectoine was the major solute that was synthesized in response to elevated salinity, while hydroxyectoine was a minor solute. However, the hydroxyectoine/ectoine ratio increased from 0.04 at 3 % NaCl to 0.45 at 15 % NaCl in the late exponential growth phase. A cluster of ectoine biosynthesis genes was identified, including three genes in the order of ectA, ectB, and ectC. The hydroxyectoine biosynthesis gene ectD was not part of the ectABC gene cluster. Reverse transcription-quantitative polymerase chain reactions (RT-qPCR) showed that the expression of the ect genes was salinity dependent. The expression of ectABC reached a maximum at 12 % NaCl, while ectD expression increased up to 15 % NaCl. Ectoine and hydroxyectoine production was growth phase dependent. The hydroxyectoine/ectoine ratio increased from 0.018 in the early exponential phase to 0.11 in the stationary phase at 5 % NaCl. Hydroxyectoine biosynthesis started much later than ectoine biosynthesis after osmotic shock, and the temporal expression of the ect genes differed under these conditions, with the ectABC genes being expressed first, followed by ectD gene. Increased culture salinity triggered ectoine or hydroxyectoine uptake when they were added to the medium. Hydroxyectoine was accumulated preferentially when both ectoine and hydroxyectoine were provided exogenously.

Internal Membrane Control in Azotobacter vinelandii

PubMed Central

Pate, Jack L.; Shah, Vinod K.; Brill, Winston J.

1973-01-01

Azotobacter vinelandii was grown on N2, NH4+, or NO3−, and an internal membrane network was observed by electron microscopy of thin sections of cells. Cells obtained in early exponential growth contained less internal membrane than did cells from cultures in late exponential growth. It seems likely that O2 has a role in regulating the amount of internal membrane structure. Images PMID:4123239

Pressure resistance of cold-shocked Escherichia coli O157:H7 in ground beef, beef gravy and peptone water.

PubMed

Baccus-Taylor, G S H; Falloon, O C; Henry, N

2015-06-01

(i) To study the effects of cold shock on Escherichia coli O157:H7 cells. (ii) To determine if cold-shocked E. coli O157:H7 cells at stationary and exponential phases are more pressure-resistant than their non-cold-shocked counterparts. (iii) To investigate the baro-protective role of growth media (0·1% peptone water, beef gravy and ground beef). Quantitative estimates of lethality and sublethal injury were made using the differential plating method. There were no significant differences (P > 0·05) in the number of cells killed; cold-shocked or non-cold-shocked. Cells grown in ground beef (stationary and exponential phases) experienced lowest death compared with peptone water and beef gravy. Cold-shock treatment increased the sublethal injury to cells cultured in peptone water (stationary and exponential phases) and ground beef (exponential phase), but decreased the sublethal injury to cells in beef gravy (stationary phase). Cold shock did not confer greater resistance to stationary or exponential phase cells pressurized in peptone water, beef gravy or ground beef. Ground beef had the greatest baro-protective effect. Real food systems should be used in establishing food safety parameters for high-pressure treatments; micro-organisms are less resistant in model food systems, the use of which may underestimate the organisms' resistance. © 2015 The Society for Applied Microbiology.

Anti-bacterial effect of essential oil from Xanthium strumarium against shiga toxin-producing Escherichia coli.

PubMed

Sharifi-Rad, J; Soufi, L; Ayatollahi, S A M; Iriti, M; Sharifi-Rad, M; Varoni, E M; Shahri, F; Esposito, S; Kuhestani, K; Sharifi-Rad, M

2016-09-19

Shiga toxin-producing Escherichia coli (STEC) serotype O157:H7 is one of the most important human pathogenic microorganisms, which can cause life-threatening infections. Xanthium strumarium L. is a plant with anti-bacterial activity against gram-negative and gram-positive bacteria. This study aims to demonstrate in vitro efficacy of the essential oil (EO) extracted from Xanthium strumarium L. against E. coli O157:H7. Using the agar test diffusion, the effect of Xanthium strumarium L. EO (5, 10, 15, 30, 60, and 120 mg/mL) was verified at each of the four different growth phases of E. coli O157:H7. Cell counts of viable cells and colony forming unit (CFU) were determined at regular time points using Breed's method and colony counting method, respectively. No viable cell was detectable after the 1 hour-exposure to X. strumarium EO at 30, 60, and 120 mg/mL concentrations. No bacterial colony was formed after 1 h until the end of the incubation period at 24 h. At lower concentrations, the number of bacteria cells decreased and colonies could be observed only after incubation. At the exponential phase, the EO at 15 mg/mL was only bacteriostatic, while from 30 mg/mL started to be bactericidal. X. strumarium EO antibacterial activity against Shiga toxin-producing E. coli O157:H7 is dependent on EO concentration and physiological state of the microorganisms tested. The best inhibitory activity was achieved during the late exponential and the stationary phases.

Correlation between the change in the kinetics of the ribosomal RNA rrnB P2 promoter and the transition from lag to exponential phase with Pseudomonas fluorescens.

PubMed

McKellar, Robin C

2008-01-15

Developing accurate mathematical models to describe the pre-exponential lag phase in food-borne pathogens presents a considerable challenge to food microbiologists. While the growth rate is influenced by current environmental conditions, the lag phase is affected in addition by the history of the inoculum. A deeper understanding of physiological changes taking place during the lag phase would improve accuracy of models, and in earlier studies a strain of Pseudomonas fluorescens containing the Tn7-luxCDABE gene cassette regulated by the rRNA promoter rrnB P2 was used to measure the influence of starvation, growth temperature and sub-lethal heating on promoter expression and subsequent growth. The present study expands the models developed earlier to include a model which describes the change from exponential to linear increase in promoter expression with time when the exponential phase of growth commences. A two-phase linear model with Poisson weighting was used to estimate the lag (LPDLin) and the rate (RLin) for this linear increase in bioluminescence. The Spearman rank correlation coefficient (r=0.830) between the LPDLin and the growth lag phase (LPDOD) was extremely significant (P

Constraining f(T) teleparallel gravity by big bang nucleosynthesis: f(T) cosmology and BBN.

PubMed

Capozziello, S; Lambiase, G; Saridakis, E N

2017-01-01

We use Big Bang Nucleosynthesis (BBN) observational data on the primordial abundance of light elements to constrain f ( T ) gravity. The three most studied viable f ( T ) models, namely the power law, the exponential and the square-root exponential are considered, and the BBN bounds are adopted in order to extract constraints on their free parameters. For the power-law model, we find that the constraints are in agreement with those obtained using late-time cosmological data. For the exponential and the square-root exponential models, we show that for reliable regions of parameters space they always satisfy the BBN bounds. We conclude that viable f ( T ) models can successfully satisfy the BBN constraints.

Halophilic archaea cultivated from surface sterilized middle-late eocene rock salt are polyploid.

PubMed

Jaakkola, Salla T; Zerulla, Karolin; Guo, Qinggong; Liu, Ying; Ma, Hongling; Yang, Chunhe; Bamford, Dennis H; Chen, Xiangdong; Soppa, Jörg; Oksanen, Hanna M

2014-01-01

Live bacteria and archaea have been isolated from several rock salt deposits of up to hundreds of millions of years of age from all around the world. A key factor affecting their longevity is the ability to keep their genomic DNA intact, for which efficient repair mechanisms are needed. Polyploid microbes are known to have an increased resistance towards mutations and DNA damage, and it has been suggested that microbes from deeply buried rock salt would carry several copies of their genomes. Here, cultivable halophilic microbes were isolated from a surface sterilized middle-late Eocene (38-41 million years ago) rock salt sample, drilled from the depth of 800 m at Yunying salt mine, China. Eight unique isolates were obtained, which represented two haloarchaeal genera, Halobacterium and Halolamina. We used real-time PCR to show that our isolates are polyploid, with genome copy numbers of 11-14 genomes per cell in exponential growth phase. The ploidy level was slightly downregulated in stationary growth phase, but the cells still had an average genome copy number of 6-8. The polyploidy of halophilic archaea living in ancient rock salt might be a factor explaining how these organisms are able to overcome the challenge of prolonged survival during their entombment.

Probing Gamma-ray Emission of Geminga and Vela with Non-stationary Models

NASA Astrophysics Data System (ADS)

Chai, Yating; Cheng, Kwong-Sang; Takata, Jumpei

2016-06-01

It is generally believed that the high energy emissions from isolated pulsars are emitted from relativistic electrons/positrons accelerated in outer magnetospheric accelerators (outergaps) via a curvature radiation mechanism, which has a simple exponential cut-off spectrum. However, many gamma-ray pulsars detected by the Fermi LAT (Large Area Telescope) cannot be fitted by simple exponential cut-off spectrum, and instead a sub-exponential is more appropriate. It is proposed that the realistic outergaps are non-stationary, and that the observed spectrum is a superposition of different stationary states that are controlled by the currents injected from the inner and outer boundaries. The Vela and Geminga pulsars have the largest fluxes among all targets observed, which allows us to carry out very detailed phase-resolved spectral analysis. We have divided the Vela and Geminga pulsars into 19 (the off pulse of Vela was not included) and 33 phase bins, respectively. We find that most phase resolved spectra still cannot be fitted by a simple exponential spectrum: in fact, a sub-exponential spectrum is necessary. We conclude that non-stationary states exist even down to the very fine phase bins.

Structure of the nucleoid in cells of Streptococcus faecalis.

PubMed Central

Daneo-Moore, L; Dicker, D; Higgins, M L

1980-01-01

The structure of the nucleoid of Streptococcus faecalis (ATCC 9790) was examined and compared in the unfixed and fixed states by immersive refractometry and electron microscopy. It appears from these studies that the nucleoid structure is much more centralized in unfixed chloramphenicol-treated (stationary-phase) cells than it is in cells in the exponential phase of growth. The more dispersed configuration of the exponential-phase nucleoid could be preserved by fixation in glutaraldehyde, but not in Formalin or in osmium tetroxide. One important factor in explaining these differences in preservation is that glutaraldehyde (but not Formalin or osmium tetroxide) can rapidly cross-link the amino groups of macromolecules in cells. It was also observed that osmium tetroxide resulted in a preferential breakdown of nascent ribonucleic acid. These results are interpreted as indicating that glutaraldehyde is able to stabilize the exponential-phase nucleoid before it assumes the more central appearance seen in osmium tetroxide- and Formalin-fixed cells. These results are discussed in terms of the proposed organization of the exponential-phase nucleoid in unfixed cells. Images PMID:6767695

Enhancement of L-phenylalanine production by engineered Escherichia coli using phased exponential L-tyrosine feeding combined with nitrogen source optimization.

PubMed

Yuan, Peipei; Cao, Weijia; Wang, Zhen; Chen, Kequan; Li, Yan; Ouyang, Pingkai

2015-07-01

Nitrogen source optimization combined with phased exponential L-tyrosine feeding was employed to enhance L-phenylalanine production by a tyrosine-auxotroph strain, Escherichia coli YP1617. The absence of (NH4)2SO4, the use of corn steep powder and yeast extract as composite organic nitrogen source were more suitable for cell growth and L-phenylalanine production. Moreover, the optimal initial L-tyrosine level was 0.3 g L(-1) and exponential L-tyrosine feeding slightly improved L-phenylalanine production. Nerveless, L-phenylalanine production was greatly enhanced by a strategy of phased exponential L-tyrosine feeding, where exponential feeding was started at the set specific growth rate of 0.08, 0.05, and 0.02 h(-1) after 12, 32, and 52 h, respectively. Compared with exponential L-tyrosine feeding at the set specific growth rate of 0.08 h(-1), the developed strategy obtained a 15.33% increase in L-phenylalanine production (L-phenylalanine of 56.20 g L(-1)) and a 45.28% decrease in L-tyrosine supplementation. Copyright © 2014 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Gene expression profiles of Vibrio parahaemolyticus in the early stationary phase.

PubMed

Meng, L; Alter, T; Aho, T; Huehn, S

2015-09-01

Vibrio (V.) parahaemolyticus is an aquatic bacterium capable of causing foodborne gastroenteritis. In the environment or the food chain, V. parahaemolyticus cells are usually forced into the stationary phase, the common phase for bacterial survival in the environment. So far, little is known about whole genomic expression of V. parahaemolyticus in the early stationary phase compared with the exponential growth phase. We performed whole transcriptomic profiling of V. parahaemolyticus cells in both phases (exponential and early stationary phase). Our data showed in total that 172 genes were induced in early stationary phase, while 61 genes were repressed in early stationary phase compared with the exponential phase. Three functional categories showed stable gene expression in the early stationary phase. Eleven functional categories showed that up-regulation of genes was dominant over down-regulation in the early stationary phase. Although genes related to endogenous metabolism were repressed in the early stationary phase, massive regulation of gene expression occurred in the early stationary phase, indicating the expressed gene set of V. parahaemolyticus in the early stationary phase impacts environmental survival. Vibrio (V.) parahaemolyticus is one of the main bacterial causes of foodborne intestinal infections. This bacterium usually is forced into stationary phase in the environment, which includes, e.g. seafood. When bacteria are in stationary phase, physiological changes can lead to a resistance to many stresses, including physical and chemical challenges during food processing. To the best of our knowledge, highlighting the whole genome expression changes in the early stationary phase compared with exponential phase, as well as the investigation of physiological changes of V. parahaemolyticus such as the survival mechanism in the stationary phase has been the very first study in this field. © 2015 The Society for Applied Microbiology.

SlyD-dependent nickel delivery limits maturation of [NiFe]-hydrogenases in late-stationary phase Escherichia coli cells.

PubMed

Pinske, Constanze; Sargent, Frank; Sawers, R Gary

2015-04-01

Fermentatively growing Escherichia coli cells have three active [NiFe]-hydrogenases (Hyd), two of which, Hyd-1 and Hyd-2, contribute to H2 oxidation while Hyd-3 couples formate oxidation to H2 evolution. Biosynthesis of all Hyd involves the insertion of a Fe(CN)2CO group and a subsequent insertion of nickel ions through the HypA/HybF, HypB and SlyD proteins. With high nickel concentrations the presence of none of these proteins is required, but under normal growth conditions and during late stationary growth SlyD is important for hydrogenase activities. The slyD mutation reduced H2 production during exponential phase growth by about 50%. Assaying stationary phase grown cells for the coupling of Hyd activity to the respiratory chain or formate-dependent H2 evolution showed that SlyD is essential for both H2 evolution and H2 oxidation. Although introduction of plasmid-coded slyD resulted in an overall decrease of Hyd-2 polypeptides in slyD and hypA slyD mutants, processing and dye-reducing activity of the Hyd-2 enzyme was nevertheless restored. Similarly, introduction of the slyD plasmid restored only some H2 evolution in the slyD mutant while Hyd-3 polypeptides and dye-reducing activity were fully restored. Taken together, these results indicate an essential role for SlyD in the generation of the fully cofactor-equipped hydrogenase large subunits in the stationary phase where the level of each Hyd enzyme is finely tuned by SlyD for optimal enzyme activity.

Fractional Stability of Trunk Acceleration Dynamics of Daily-Life Walking: Toward a Unified Concept of Gait Stability

PubMed Central

Ihlen, Espen A. F.; van Schooten, Kimberley S.; Bruijn, Sjoerd M.; Pijnappels, Mirjam; van Dieën, Jaap H.

2017-01-01

Over the last decades, various measures have been introduced to assess stability during walking. All of these measures assume that gait stability may be equated with exponential stability, where dynamic stability is quantified by a Floquet multiplier or Lyapunov exponent. These specific constructs of dynamic stability assume that the gait dynamics are time independent and without phase transitions. In this case the temporal change in distance, d(t), between neighboring trajectories in state space is assumed to be an exponential function of time. However, results from walking models and empirical studies show that the assumptions of exponential stability break down in the vicinity of phase transitions that are present in each step cycle. Here we apply a general non-exponential construct of gait stability, called fractional stability, which can define dynamic stability in the presence of phase transitions. Fractional stability employs the fractional indices, α and β, of differential operator which allow modeling of singularities in d(t) that cannot be captured by exponential stability. The fractional stability provided an improved fit of d(t) compared to exponential stability when applied to trunk accelerations during daily-life walking in community-dwelling older adults. Moreover, using multivariate empirical mode decomposition surrogates, we found that the singularities in d(t), which were well modeled by fractional stability, are created by phase-dependent modulation of gait. The new construct of fractional stability may represent a physiologically more valid concept of stability in vicinity of phase transitions and may thus pave the way for a more unified concept of gait stability. PMID:28900400

A new mechanistic growth model for simultaneous determination of lag phase duration and exponential growth rate and a new Belehdradek-type model for evaluating the effect of temperature on growth rate

USDA-ARS?s Scientific Manuscript database

A new mechanistic growth model was developed to describe microbial growth under isothermal conditions. The new mathematical model was derived from the basic observation of bacterial growth that may include lag, exponential, and stationary phases. With this model, the lag phase duration and exponen...

[Is it possible to "cancel" aging process of cell cultures under optimal conditions for cultivation?].

PubMed

Bozhkov, A I; Kovaleva, M K; Menzianova, N G

2011-01-01

The characteristics of the cells epigenotypes Dunaliella viridis Teod. in the process of chronological and replicative aging were investigated. By 40th day of accumulative cultivation (which coincided with the stationary growth phase) DNA content in the cells of Dunaliella viridis increased 2 times, triacylglycerides 3 times, beta-carotene and carbonyl proteins 2 times, RNA content decreased in comparison with cells in exponential growth phase, i. e., the 40th day of growth of culture forms the age-related epigenotype. 4 received subcultures were being transplanted during 2 years in mid-logarithmic growth phase (subculture-10), early stationary phase of growth (subculture-20), in the mid-stationary growth phase (subculture-30), and late stationary growth phase (subculture-40). It is shown that epigenotype of subculture-10 remained unchanged over 2 years of cultivation, i. e., it does not manifest replicative aging. At the same time, the subculture-20, although long enough (at least 40 passages), maintained epigenotype characteristic of young cultures, and showed age-related changes. Pronounced age-dependent changes of epigenotype in the course of cultivation were identified for subculture-30, and subculture-40 was characterized by unstable epigenotype. Thus, cultivation conditions determine the intensity of replicative aging in Dunaliella viridis.

Fatty acid synthesis in Escherichia coli

PubMed Central

Knivett, V. A.; Cullen, Julia

1967-01-01

1. Fatty acid formation by cells of a strain of Escherichia coli has been studied in the exponential, post-exponential and stationary phases of growth. 2. During the exponential phase of growth, the metabolic quotient (mμmoles of fatty acid synthesized/mg. dry wt. of cells/hr.) for each fatty acid in the extractable lipid was constant. 3. The newly synthesized fatty acid mixtures produced during this phase contained hexadecanoic acid (41%), hexadecenoic acid (31%), octadecenoic acid (21%) and the C17-cyclopropane acid, methylenehexadecanoic acid (4%). 4. As the proportion of newly synthesized material increased, changes in the fatty acid composition of the cells during this period were towards this constant composition. 5. Abrupt changes in fatty acid synthesis occurred when exponential growth ceased. 6. In media in which glycerol, or SO42− or Mg2+, was growth-limiting there was a small accumulation of C17-cyclopropane acid in cells growing in the post-exponential phase of growth. 7. Where either NH4+ or PO43− was growth-limiting and there were adequate supplies of glycerol, Mg2+ and SO42−, there was a marked accumulation of C17-cyclopropane acid and C19-cyclopropane acid appeared. 8. Under appropriate conditions the metabolic quotient for C17-cyclopropane acid increased up to sevenfold at the end of exponential growth. Simultaneously the metabolic quotients of the other acids fell. 9. A mixture of glycerol, Mg2+ and SO42− stimulated cyclopropane acid formation in resting cells. PMID:5340364

Recovery of cat retinal ganglion cell sensitivity following pigment bleaching.

PubMed Central

Bonds, A B; Enroth-Cugell, C

1979-01-01

1. The threshold illuminance for small spot stimulation of on-centre cat retinal ganglion cells was plotted vs. time after exposure to adapting light sufficiently strong to bleach significant amounts of rhodopsin. 2. When the entire receptive field of an X- or Y-type ganglion cell is bleached by at most 40%, recovery of the cell's rod-system proceeds in two phases: an early relatively fast one during which the response appears transient, and a late, slower one during which responses become more sustained. Log threshold during the later phase is well fit by an exponential in time (tau = 11.5-38 min). 3. After bleaches of 90% of the underlying pigment, threshold is cone-determined for as long as 40 min. Rod threshold continues to decrease for at least 85 min after the bleach. 4. The rate of recovery is slower after strong than after weak bleaches; 10 and 90% bleaches yield time constants for the later phase of 11.5 and 38 min, respectively. This contrasts with an approximate time constant of 11 min for rhodopsin regeneration following any bleach. 5. The relationship between the initial elevation of log rod threshold extrapolated from the fitted exponential curves and the initial amount of pigment bleached is monotonic, but nonlinear. 6. After a bleaching exposure, the maintained discharge is initially very regular. The firing rate first rises, then falls to the pre-bleach level, with more extended time courses of change in firing rate after stronger exposures. The discharge rate is restored before threshold has recovered fully. 7. The change in the response vs. log stimulus relationship after bleaching is described as a shift of the curve to the right, paired with a decrease in slope of the linear segment of the curve. PMID:521963

Competitive fitness during feast and famine: how SOS DNA polymerases influence physiology and evolution in Escherichia coli.

PubMed

Corzett, Christopher H; Goodman, Myron F; Finkel, Steven E

2013-06-01

Escherichia coli DNA polymerases (Pol) II, IV, and V serve dual roles by facilitating efficient translesion DNA synthesis while simultaneously introducing genetic variation that can promote adaptive evolution. Here we show that these alternative polymerases are induced as cells transition from exponential to long-term stationary-phase growth in the absence of induction of the SOS regulon by external agents that damage DNA. By monitoring the relative fitness of isogenic mutant strains expressing only one alternative polymerase over time, spanning hours to weeks, we establish distinct growth phase-dependent hierarchies of polymerase mutant strain competitiveness. Pol II confers a significant physiological advantage by facilitating efficient replication and creating genetic diversity during periods of rapid growth. Pol IV and Pol V make the largest contributions to evolutionary fitness during long-term stationary phase. Consistent with their roles providing both a physiological and an adaptive advantage during stationary phase, the expression patterns of all three SOS polymerases change during the transition from log phase to long-term stationary phase. Compared to the alternative polymerases, Pol III transcription dominates during mid-exponential phase; however, its abundance decreases to <20% during long-term stationary phase. Pol IV transcription dominates as cells transition out of exponential phase into stationary phase and a burst of Pol V transcription is observed as cells transition from death phase to long-term stationary phase. These changes in alternative DNA polymerase transcription occur in the absence of SOS induction by exogenous agents and indicate that cell populations require appropriate expression of all three alternative DNA polymerases during exponential, stationary, and long-term stationary phases to attain optimal fitness and undergo adaptive evolution.

f(T,T) gravity and cosmology

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

Harko, Tiberiu; Lobo, Francisco S.N.; Otalora, G.

2014-12-01

We present an extension of f(T) gravity, allowing for a general coupling of the torsion scalar T with the trace of the matter energy-momentum tensor T. The resulting f(T,T) theory is a new modified gravity, since it is different from all the existing torsion or curvature based constructions. Applied to a cosmological framework, it leads to interesting phenomenology. In particular, one can obtain a unified description of the initial inflationary phase, the subsequent non-accelerating, matter-dominated expansion, and then the transition to a late-time accelerating phase. Additionally, the effective dark energy sector can be quintessence or phantom-like, or exhibit the phantom-dividemore » crossing during the evolution. Moreover, in the far future the universe results either to a de Sitter exponential expansion, or to eternal power-law accelerated expansions. Finally, a detailed study of the scalar perturbations at the linear level reveals that f(T,T) cosmology can be free of ghosts and instabilities for a wide class of ansatzes and model parameters.« less

Treatment of late time instabilities in finite-difference EMP scattering codes

NASA Astrophysics Data System (ADS)

Simpson, L. T.; Holland, R.; Arman, S.

1982-12-01

Constraints applicable to a finite difference mesh for solution of Maxwell's equations are defined. The equations are applied in the time domain for computing electromagnetic coupling to complex structures, e.g., rectangular, cylindrical, or spherical. In a spatially varying grid, the amplitude growth of high frequency waves becomes exponential through multiple reflections from the outer boundary in cases of late-time solution. The exponential growth of the numerical noise exceeds the value of the real signal. The correction technique employs an absorbing surface and a radiating boundary, along with tailored selection of the grid mesh size. High frequency noise is removed through use of a low-pass digital filter, a linear least squares fit is made to thy low frequency filtered response, and the original, filtered, and fitted data are merged to preserve the high frequency early-time response.

A Nonequilibrium Rate Formula for Collective Motions of Complex Molecular Systems

NASA Astrophysics Data System (ADS)

Yanao, Tomohiro; Koon, Wang Sang; Marsden, Jerrold E.

2010-09-01

We propose a compact reaction rate formula that accounts for a non-equilibrium distribution of residence times of complex molecules, based on a detailed study of the coarse-grained phase space of a reaction coordinate. We take the structural transition dynamics of a six-atom Morse cluster between two isomers as a prototype of multi-dimensional molecular reactions. Residence time distribution of one of the isomers shows an exponential decay, while that of the other isomer deviates largely from the exponential form and has multiple peaks. Our rate formula explains such equilibrium and non-equilibrium distributions of residence times in terms of the rates of diffusions of energy and the phase of the oscillations of the reaction coordinate. Rapid diffusions of energy and the phase generally give rise to the exponential decay of residence time distribution, while slow diffusions give rise to a non-exponential decay with multiple peaks. We finally make a conjecture about a general relationship between the rates of the diffusions and the symmetry of molecular mass distributions.

A mutant (‘lab strain’) of the hyperthermophilic archaeon Pyrococcus furiosus, lacking flagella, has unusual growth physiology

DOE PAGES

Lewis, Derrick L.; Notey, Jaspreet S.; Chandrayan, Sanjeev K.; ...

2014-12-04

In this paper, a mutant (‘lab strain’) of the hyperthermophilic archaeon Pyrococcus furiosus DSM3638 exhibited an extended exponential phase and atypical cell aggregation behavior. Genomic DNA from the mutant culture was sequenced and compared to wild-type (WT) DSM3638, revealing 145 genes with one or more insertions, deletions, or substitutions (12 silent, 33 amino acid substitutions, and 100 frame shifts). Approximately, half of the mutated genes were transposases or hypothetical proteins. The WT transcriptome revealed numerous changes in amino acid and pyrimidine biosynthesis pathways coincidental with growth phase transitions, unlike the mutant whose transcriptome reflected the observed prolonged exponential phase. Targetedmore » gene deletions, based on frame-shifted ORFs in the mutant genome, in a genetically tractable strain of P. furiosus (COM1) could not generate the extended exponential phase behavior observed for the mutant. For example, a putative radical SAM family protein (PF2064) was the most highly up-regulated ORF (>25-fold) in the WT between exponential and stationary phase, although this ORF was unresponsive in the mutant; deletion of this gene in P. furiosus COM1 resulted in no apparent phenotype. On the other hand, frame-shifting mutations in the mutant genome negatively impacted transcription of a flagellar biosynthesis operon (PF0329-PF0338).Consequently, cells in the mutant culture lacked flagella and, unlike the WT, showed minimal evidence of exopolysaccharide-based cell aggregation in post-exponential phase. Finally, electron microscopy of PF0331-PF0337 deletions in P. furiosus COM1 showed that absence of flagella impacted normal cell aggregation behavior and, furthermore, indicated that flagella play a key role, beyond motility, in the growth physiology of P. furiosus.« less

A mutant (‘lab strain’) of the hyperthermophilic archaeon Pyrococcus furiosus, lacking flagella, has unusual growth physiology

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

Lewis, Derrick L.; Notey, Jaspreet S.; Chandrayan, Sanjeev K.

In this paper, a mutant (‘lab strain’) of the hyperthermophilic archaeon Pyrococcus furiosus DSM3638 exhibited an extended exponential phase and atypical cell aggregation behavior. Genomic DNA from the mutant culture was sequenced and compared to wild-type (WT) DSM3638, revealing 145 genes with one or more insertions, deletions, or substitutions (12 silent, 33 amino acid substitutions, and 100 frame shifts). Approximately, half of the mutated genes were transposases or hypothetical proteins. The WT transcriptome revealed numerous changes in amino acid and pyrimidine biosynthesis pathways coincidental with growth phase transitions, unlike the mutant whose transcriptome reflected the observed prolonged exponential phase. Targetedmore » gene deletions, based on frame-shifted ORFs in the mutant genome, in a genetically tractable strain of P. furiosus (COM1) could not generate the extended exponential phase behavior observed for the mutant. For example, a putative radical SAM family protein (PF2064) was the most highly up-regulated ORF (>25-fold) in the WT between exponential and stationary phase, although this ORF was unresponsive in the mutant; deletion of this gene in P. furiosus COM1 resulted in no apparent phenotype. On the other hand, frame-shifting mutations in the mutant genome negatively impacted transcription of a flagellar biosynthesis operon (PF0329-PF0338).Consequently, cells in the mutant culture lacked flagella and, unlike the WT, showed minimal evidence of exopolysaccharide-based cell aggregation in post-exponential phase. Finally, electron microscopy of PF0331-PF0337 deletions in P. furiosus COM1 showed that absence of flagella impacted normal cell aggregation behavior and, furthermore, indicated that flagella play a key role, beyond motility, in the growth physiology of P. furiosus.« less

Use of chemostat cultures mimicking different phases of wine fermentations as a tool for quantitative physiological analysis

PubMed Central

2014-01-01

Background Saccharomyces cerevisiae is the most relevant yeast species conducting the alcoholic fermentation that takes place during winemaking. Although the physiology of this model organism has been extensively studied, systematic quantitative physiology studies of this yeast under winemaking conditions are still scarce, thus limiting the understanding of fermentative metabolism of wine yeast strains and the systematic description, modelling and prediction of fermentation processes. In this study, we implemented and validated the use of chemostat cultures as a tool to simulate different stages of a standard wine fermentation, thereby allowing to implement metabolic flux analyses describing the sequence of metabolic states of S. cerevisae along the wine fermentation. Results Chemostat cultures mimicking the different stages of standard wine fermentations of S. cerevisiae EC1118 were performed using a synthetic must and strict anaerobic conditions. The simulated stages corresponded to the onset of the exponential growth phase, late exponential growth phase and cells just entering stationary phase, at dilution rates of 0.27, 0.04, 0.007 h−1, respectively. Notably, measured substrate uptake and product formation rates at each steady state condition were generally within the range of corresponding conversion rates estimated during the different batch fermentation stages. Moreover, chemostat data were further used for metabolic flux analysis, where biomass composition data for each condition was considered in the stoichiometric model. Metabolic flux distributions were coherent with previous analyses based on batch cultivations data and the pseudo-steady state assumption. Conclusions Steady state conditions obtained in chemostat cultures reflect the environmental conditions and physiological states of S. cerevisiae corresponding to the different growth stages of a typical batch wine fermentation, thereby showing the potential of this experimental approach to systematically study the effect of environmental relevant factors such as temperature, sugar concentration, C/N ratio or (micro) oxygenation on the fermentative metabolism of wine yeast strains. PMID:24928139

Exponential Speedup of Quantum Annealing by Inhomogeneous Driving of the Transverse Field

NASA Astrophysics Data System (ADS)

Susa, Yuki; Yamashiro, Yu; Yamamoto, Masayuki; Nishimori, Hidetoshi

2018-02-01

We show, for quantum annealing, that a certain type of inhomogeneous driving of the transverse field erases first-order quantum phase transitions in the p-body interacting mean-field-type model with and without longitudinal random field. Since a first-order phase transition poses a serious difficulty for quantum annealing (adiabatic quantum computing) due to the exponentially small energy gap, the removal of first-order transitions means an exponential speedup of the annealing process. The present method may serve as a simple protocol for the performance enhancement of quantum annealing, complementary to non-stoquastic Hamiltonians.

2D motility tracking of Pseudomonas putida KT2440 in growth phases using video microscopy

PubMed Central

Davis, Michael L.; Mounteer, Leslie C.; Stevens, Lindsey K.; Miller, Charles D.; Zhou, Anhong

2011-01-01

Pseudomonas putida KT2440 is a gram negative motile soil bacterium important in bioremediation and biotechnology. Thus, it is important to understand its motility characteristics as individuals and in populations. Population characteristics were determined using a modified Gompertz model. Video microscopy and imaging software were utilized to analyze two dimensional (2D) bacteria movement tracks to quantify individual bacteria behavior. It was determined that inoculum density increased the lag time as seeding densities decreased, and that the maximum specific growth rate decreased as seeding densities increased. Average bacterial velocity remained relatively similar throughout exponential growth phase (~20.9 µm/sec), while maximum velocities peak early in exponential growth phase at a velocity of 51.2 µm/sec. Pseudomonas putida KT2440 also favor smaller turn angles indicating they often continue in the same direction after a change in flagella rotation throughout the exponential growth phase. PMID:21334971

Effects of proliferation on the decay of thermotolerance in Chinese hamster cells.

PubMed

Armour, E P; Li, G C; Hahn, G M

1985-09-01

Development and decay of thermotolerance were observed in Chinese hamster HA-1 cells. The thermotolerance kinetics of exponentially growing and fed plateau-phase cells were compared. Following a 10-min heat exposure at 45 degrees C, cells in both growth states had similar rates of development of tolerance to a subsequent 45-min exposure at 45 degrees C. This thermotolerant state started to decay between 12 and 24 hr after the initial heat exposure. The decay appeared to initiate slightly sooner in the exponentially growing cells when compared to the fed plateau-phase cells. During the decay phase, the rate of thermotolerance decay was similar in the two growth conditions. In other experiments, cells were induced to divide at a slower rate by chronic growth (3 months) in a low concentration of fetal calf serum. Under these low serum conditions cells became more sensitive to heat and the rate of decay of thermotolerance remained the same for exponentially growing cells. Plateau-phase cells were also more sensitive, but thermotolerance decayed more rapidly in these cells. Although dramatic cell cycle perturbations were seen in the exponentially growing cells, these changes appeared not to be related to thermotolerance kinetics.

The Mass-dependent Star Formation Histories of Disk Galaxies: Infall Model Versus Observations

NASA Astrophysics Data System (ADS)

Chang, R. X.; Hou, J. L.; Shen, S. Y.; Shu, C. G.

2010-10-01

We introduce a simple model to explore the star formation histories of disk galaxies. We assume that the disk originate and grows by continuous gas infall. The gas infall rate is parameterized by the Gaussian formula with one free parameter: the infall-peak time tp . The Kennicutt star formation law is adopted to describe how much cold gas turns into stars. The gas outflow process is also considered in our model. We find that, at a given galactic stellar mass M *, the model adopting a late infall-peak time tp results in blue colors, low-metallicity, high specific star formation rate (SFR), and high gas fraction, while the gas outflow rate mainly influences the gas-phase metallicity and star formation efficiency mainly influences the gas fraction. Motivated by the local observed scaling relations, we "construct" a mass-dependent model by assuming that the low-mass galaxy has a later infall-peak time tp and a larger gas outflow rate than massive systems. It is shown that this model can be in agreement with not only the local observations, but also with the observed correlations between specific SFR and galactic stellar mass SFR/M * ~ M * at intermediate redshifts z < 1. Comparison between the Gaussian-infall model and the exponential-infall model is also presented. It shows that the exponential-infall model predicts a higher SFR at early stage and a lower SFR later than that of Gaussian infall. Our results suggest that the Gaussian infall rate may be more reasonable in describing the gas cooling process than the exponential infall rate, especially for low-mass systems.

Exponential-fitted methods for integrating stiff systems of ordinary differential equations: Applications to homogeneous gas-phase chemical kinetics

NASA Technical Reports Server (NTRS)

Pratt, D. T.

1984-01-01

Conventional algorithms for the numerical integration of ordinary differential equations (ODEs) are based on the use of polynomial functions as interpolants. However, the exact solutions of stiff ODEs behave like decaying exponential functions, which are poorly approximated by polynomials. An obvious choice of interpolant are the exponential functions themselves, or their low-order diagonal Pade (rational function) approximants. A number of explicit, A-stable, integration algorithms were derived from the use of a three-parameter exponential function as interpolant, and their relationship to low-order, polynomial-based and rational-function-based implicit and explicit methods were shown by examining their low-order diagonal Pade approximants. A robust implicit formula was derived by exponential fitting the trapezoidal rule. Application of these algorithms to integration of the ODEs governing homogenous, gas-phase chemical kinetics was demonstrated in a developmental code CREK1D, which compares favorably with the Gear-Hindmarsh code LSODE in spite of the use of a primitive stepsize control strategy.

Design and optimization of a novel reverse transcription linear-after-the-exponential PCR for the detection of foot-and-mouth disease virus.

PubMed

Pierce, K E; Mistry, R; Reid, S M; Bharya, S; Dukes, J P; Hartshorn, C; King, D P; Wangh, L J

2010-07-01

A novel molecular assay for the detection of foot-and-mouth disease virus (FMDV) was developed using linear-after-the-exponential polymerase chain reaction (LATE-PCR). Pilot experiments using synthetic DNA targets demonstrated the ability of LATE-PCR to quantify initial target concentration through endpoint detection. A two-step protocol involving reverse transcription (RT) followed by LATE-PCR was then used to confirm the ability of the assay to detect FMDV RNA. Finally, RT and LATE-PCR were combined in a one-step duplex assay for co-amplification of an FMDV RNA segment and an internal control comprised of an Armored RNA. In that form, each of the excess primers in the reaction mixture hybridize to their respective RNA targets during a short pre-incubation, then generate cDNA strands during a 3-min RT step at 60°C, and the resulting cDNA is amplified by LATE-PCR without intervening sample processing. The RT-LATE-PCR assay generates fluorescent signals at endpoint that are proportional to the starting number of RNA targets and can detect a range of sequence variants using a single mismatch-tolerant probe. In addition to offering improvements over current laboratory-based molecular diagnostic assays for FMDV, this new assay is compatible with a novel portable ('point-of-care') device, the BioSeeq II, designed for the rapid diagnosis of FMD in the field. © 2009 The Authors. Journal compilation © 2009 The Society for Applied Microbiology.

Experimental tests of truncated diffusion in fault damage zones

NASA Astrophysics Data System (ADS)

Suzuki, Anna; Hashida, Toshiyuki; Li, Kewen; Horne, Roland N.

2016-11-01

Fault zones affect the flow paths of fluids in groundwater aquifers and geological reservoirs. Fault-related fracture damage decreases to background levels with increasing distance from the fault core according to a power law. This study investigated mass transport in such a fault-related structure using nonlocal models. A column flow experiment is conducted to create a permeability distribution that varies with distance from a main conduit. The experimental tracer response curve is preasymptotic and implies subdiffusive transport, which is slower than the normal Fickian diffusion. If the surrounding area is a finite domain, an upper truncated behavior in tracer response (i.e., exponential decline at late times) is observed. The tempered anomalous diffusion (TAD) model captures the transition from subdiffusive to Fickian transport, which is characterized by a smooth transition from power-law to an exponential decline in the late-time breakthrough curves.

Metabolism of ferulic acid during growth of Lactobacillus plantarum and Lactobacillus collinoides.

PubMed

Knockaert, Dries; Raes, Katleen; Wille, Christophe; Struijs, Karin; Van Camp, John

2012-08-30

Food-isolated lactic acid bacteria can transform ferulic acid (FA) into several products. Since quantification of these metabolites during the different bacterial growth phases is lacking, the aim of this study was to identify and quantify conversion products of FA and to follow the kinetics of FA metabolism during growth of Lactobacillus plantarum and Lactobacillus collinoides. Lactobacillus plantarum and Lactobacillus collinoides were incubated in MRS broth, to which different amounts of FA were added (final concentrations of 0, 0.5, 1.5 and 3 mmol L⁻¹), at 30 °C until the late stationary phase. Lactobacillus plantarum metabolised FA into 4-vinylguaiacol (4-VG) and hydroferulic acid (HFA). Conversion to 4-VG started simultaneously with the degradation of FA, while formation of HFA started in the mid-exponential phase. Lactobacillus collinoides only formed 4-VG, mainly in the stationary phase. No significant effect of the different amounts of FA was seen on the growth and fermentation characteristics of both bacteria. The results demonstrate that both bacteria are able to convert FA. However, start of conversion differs between the two strains. The different amounts of FA had no influence on the growth and fermentation characteristics of both bacteria. Copyright © 2012 Society of Chemical Industry.

Role and regulation of sigma S in general resistance conferred by low-shear simulated microgravity in Escherichia coli.

PubMed

Lynch, S V; Brodie, E L; Matin, A

2004-12-01

Life on Earth evolved in the presence of gravity, and thus it is of interest from the perspective of space exploration to determine if diminished gravity affects biological processes. Cultivation of Escherichia coli under low-shear simulated microgravity (SMG) conditions resulted in enhanced stress resistance in both exponential- and stationary-phase cells, making the latter superresistant. Given that microgravity of space and SMG also compromise human immune response, this phenomenon constitutes a potential threat to astronauts. As low-shear environments are encountered by pathogens on Earth as well, SMG-conferred resistance is also relevant to controlling infectious disease on this planet. The SMG effect resembles the general stress response on Earth, which makes bacteria resistant to multiple stresses; this response is sigma s dependent, irrespective of the growth phase. However, SMG-induced increased resistance was dependent on sigma s only in stationary phase, being independent of this sigma factor in exponential phase. sigma s concentration was some 30% lower in exponential-phase SMG cells than in normal gravity cells but was twofold higher in stationary-phase SMG cells. While SMG affected sigma s synthesis at all levels of control, the main reasons for the differential effect of this gravity condition on sigma s levels were that it rendered the sigma protein less stable in exponential phase and increased rpoS mRNA translational efficiency. Since sigma s regulatory processes are influenced by mRNA and protein-folding patterns, the data suggest that SMG may affect these configurations.

Proteomic analysis of growth phase-dependent expression of Legionella pneumophila proteins which involves regulation of bacterial virulence traits.

PubMed

Hayashi, Tsuyoshi; Nakamichi, Masahiro; Naitou, Hirotaka; Ohashi, Norio; Imai, Yasuyuki; Miyake, Masaki

2010-07-22

Legionella pneumophila, which is a causative pathogen of Legionnaires' disease, expresses its virulent traits in response to growth conditions. In particular, it is known to become virulent at a post-exponential phase in vitro culture. In this study, we performed a proteomic analysis of differences in expression between the exponential phase and post-exponential phase to identify candidates associated with L. pneumophila virulence using 2-Dimentional Fluorescence Difference Gel Electrophoresis (2D-DIGE) combined with Matrix-Assisted Laser Desorption/Ionization-Mass Spectrometry (MALDI-TOF-MS). Of 68 identified proteins that significantly differed in expression between the two growth phases, 64 were up-regulated at a post-exponential phase. The up-regulated proteins included enzymes related to glycolysis, ketone body biogenesis and poly-3-hydroxybutyrate (PHB) biogenesis, suggesting that L. pneumophila may utilize sugars and lipids as energy sources, when amino acids become scarce. Proteins related to motility (flagella components and twitching motility-associated proteins) were also up-regulated, predicting that they enhance infectivity of the bacteria in host cells under certain conditions. Furthermore, 9 up-regulated proteins of unknown function were found. Two of them were identified as novel bacterial factors associated with hemolysis of sheep red blood cells (SRBCs). Another 2 were found to be translocated into macrophages via the Icm/Dot type IV secretion apparatus as effector candidates in a reporter assay with Bordetella pertussis adenylate cyclase. The study will be helpful for virulent analysis of L. pneumophila from the viewpoint of physiological or metabolic modulation dependent on growth phase.

2D motility tracking of Pseudomonas putida KT2440 in growth phases using video microscopy.

PubMed

Davis, Michael L; Mounteer, Leslie C; Stevens, Lindsey K; Miller, Charles D; Zhou, Anhong

2011-05-01

Pseudomonas putida KT2440 is a gram negative motile soil bacterium important in bioremediation and biotechnology. Thus, it is important to understand its motility characteristics as individuals and in populations. Population characteristics were determined using a modified Gompertz model. Video microscopy and imaging software were utilized to analyze two dimensional (2D) bacteria movement tracks to quantify individual bacteria behavior. It was determined that inoculum density increased the lag time as seeding densities decreased, and that the maximum specific growth rate decreased as seeding densities increased. Average bacterial velocity remained relatively similar throughout the exponential growth phase (~20.9 μm/s), while maximum velocities peak early in the exponential growth phase at a velocity of 51.2 μm/s. P. putida KT2440 also favors smaller turn angles indicating that they often continue in the same direction after a change in flagella rotation throughout the exponential growth phase. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Scalar-fluid interacting dark energy: Cosmological dynamics beyond the exponential potential

NASA Astrophysics Data System (ADS)

Dutta, Jibitesh; Khyllep, Wompherdeiki; Tamanini, Nicola

2017-01-01

We extend the dynamical systems analysis of scalar-fluid interacting dark energy models performed in C. G. Boehmer et al., Phys. Rev. D 91, 123002 (2015), 10.1103/PhysRevD.91.123002 by considering scalar field potentials beyond the exponential type. The properties and stability of critical points are examined using a combination of linear analysis, computational methods and advanced mathematical techniques, such as center manifold theory. We show that the interesting results obtained with an exponential potential can generally be recovered also for more complicated scalar field potentials. In particular, employing power law and hyperbolic potentials as examples, we find late time accelerated attractors, transitions from dark matter to dark energy domination with specific distinguishing features, and accelerated scaling solutions capable of solving the cosmic coincidence problem.

Single-arm phase II trial design under parametric cure models.

PubMed

Wu, Jianrong

2015-01-01

The current practice of designing single-arm phase II survival trials is limited under the exponential model. Trial design under the exponential model may not be appropriate when a portion of patients are cured. There is no literature available for designing single-arm phase II trials under the parametric cure model. In this paper, a test statistic is proposed, and a sample size formula is derived for designing single-arm phase II trials under a class of parametric cure models. Extensive simulations showed that the proposed test and sample size formula perform very well under different scenarios. Copyright © 2015 John Wiley & Sons, Ltd.

Reciprocal expression of integration host factor and HU in the developmental cycle and infectivity of Legionella pneumophila.

PubMed

Morash, Michael G; Brassinga, Ann Karen C; Warthan, Michelle; Gourabathini, Poornima; Garduño, Rafael A; Goodman, Steven D; Hoffman, Paul S

2009-04-01

Legionella pneumophila is an intracellular parasite of protozoa that differentiates late in infection into metabolically dormant cysts that are highly infectious. Regulation of this process is poorly understood. Here we report that the small DNA binding regulatory proteins integration host factor (IHF) and HU are reciprocally expressed over the developmental cycle, with HU expressed during exponential phase and IHF expressed postexponentially. To assess the role of these regulatory proteins in development, chromosomal deletions were constructed. Single (ihfA or ihfB) and double deletion (Deltaihf) IHF mutants failed to grow in Acanthamoeba castellanii unless complemented in trans when expressed temporally from the ihfA promoter but not under P(tac) (isopropyl-beta-d-thiogalactopyranoside). In contrast, IHF mutants were infectious for HeLa cells, though electron microscopic examination revealed defects in late-stage cyst morphogenesis (thickened cell wall, intracytoplasmic membranes, and inclusions of poly-beta-hydroxybutyrate), and were depressed for the developmental marker MagA. Green fluorescent protein promoter fusion assays indicated that IHF and the stationary-phase sigma factor RpoS were required for full postexponential expression of magA. Finally, defects in cyst morphogenesis noted for Deltaihf mutants in HeLa cells correlated with a loss of both detergent resistance and hyperinfectivity compared with results for wild-type cysts. These studies establish IHF and HU as markers of developmental stages and show that IHF function is required for both differentiation and full virulence of L. pneumophila in natural amoebic hosts.

Global dynamics of the Escherichia coli proteome and phosphoproteome during growth in minimal medium.

PubMed

Soares, Nelson C; Spät, Philipp; Krug, Karsten; Macek, Boris

2013-06-07

Recent phosphoproteomics studies have generated relatively large data sets of bacterial proteins phosphorylated on serine, threonine, and tyrosine, implicating this type of phosphorylation in the regulation of vital processes of a bacterial cell; however, most phosphoproteomics studies in bacteria were so far qualitative. Here we applied stable isotope labeling by amino acids in cell culture (SILAC) to perform a quantitative analysis of proteome and phosphoproteome dynamics of Escherichia coli during five distinct phases of growth in the minimal medium. Combining two triple-SILAC experiments, we detected a total of 2118 proteins and quantified relative dynamics of 1984 proteins in all measured phases of growth, including 570 proteins associated with cell wall and membrane. In the phosphoproteomic experiment, we detected 150 Ser/Thr/Tyr phosphorylation events, of which 108 were localized to a specific amino acid residue and 76 were quantified in all phases of growth. Clustering analysis of SILAC ratios revealed distinct sets of coregulated proteins for each analyzed phase of growth and overrepresentation of membrane proteins in transition between exponential and stationary phases. The proteomics data indicated that proteins related to stress response typically associated with the stationary phase, including RpoS-dependent proteins, had increasing levels already during earlier phases of growth. Application of SILAC enabled us to measure median occupancies of phosphorylation sites, which were generally low (<12%). Interestingly, the phosphoproteome analysis showed a global increase of protein phosphorylation levels in the late stationary phase, pointing to a likely role of this modification in later phases of growth.

Preparation of an exponentially rising optical pulse for efficient excitation of single atoms in free space.

PubMed

Dao, Hoang Lan; Aljunid, Syed Abdullah; Maslennikov, Gleb; Kurtsiefer, Christian

2012-08-01

We report on a simple method to prepare optical pulses with exponentially rising envelope on the time scale of a few ns. The scheme is based on the exponential transfer function of a fast transistor, which generates an exponentially rising envelope that is transferred first on a radio frequency carrier, and then on a coherent cw laser beam with an electro-optical phase modulator. The temporally shaped sideband is then extracted with an optical resonator and can be used to efficiently excite a single (87)Rb atom.

Objective-function hybridization in adjoint seismic tomography

NASA Astrophysics Data System (ADS)

Yuan, Yanhua O.; Bozdaǧ, Ebru; Simons, Frederik J.; Gao, Fuchun

2017-04-01

Seismic tomography is at the threshold of a new era of massive data sets. Improving the resolution and accuracy of the estimated Earth structure by assimilating as much information as possible from every seismogram, remains a challenge. We propose the use of the "exponentiated phase'', a type of measurement that robustly captures the information contained in the variation of phase with time in the seismogram. We explore its performance in both conventional and double-difference (Yuan, Simons & Tromp, Geophys. J. Intern, 2016) adjoint seismic tomography. We introduce a hybrid approach to combine different objective functions, taking advantage of both conventional and our new measurements. We initially focus on phase measurements in global tomography. Cross-correlation measurements are generally tailored by window selection algorithms, such as FLEXWIN, to balance amplitude differences between seismic phases. However, within selection windows, such measurements still favor the larger-amplitude phases. It is also difficult to select all usable portions of the seismogram in an optimal way, such that much information may be lost, particularly the scattered waves. Time-continuous phase measurements, which associate a time shift with each point in time, have the potential to extract information from every wiggle in the seismogram without cutting it into small pieces. One such type of measurement is the instantaneous phase (Bozdaǧ, Trampert & Tromp, Geophys. J. Intern, 2011), which thus far has not been implemented in realistic seismic-tomography experiments, given how difficult the computation of phase can sometimes be. The exponentiated phase, on the other hand, is computed on the basis of the normalized analytic signal, does not need an explicit measure of phase, and is thus much easier to implement, and more practical for real-world applications. Both types of measurements carry comparable structural information when direct measurements of the phase are not wrapped. To deal with cycle skips, we use the exponentiated phase to take into account relatively small-magnitude scattered waves at long periods, while using cross-correlation measurements on windows determined by FLEXWIN to select distinct body-wave arrivals without complicating measurements due to non-linearities at short periods. We present synthetic experiments to show how exponentiated-phase, cross-correlation measurements, and their hybridization affect tomographic results. We demonstrate the use of hybrid measurements on teleseismic seismograms, in which surface waves are prominent, for continental and global seismic imaging. It is clear that the exponentiated-phase measurements behave well and provide a better representation of the smaller phases in the adjoint sources required for the computation of the misfit gradient. The combination of two different types of phase measurements in a hybrid approach moves us towards using all of the available information in a data set, addressing data quality and measurement challenges simultaneously, while negligibly affecting computation time.

Time-domain full waveform inversion using instantaneous phase information with damping

NASA Astrophysics Data System (ADS)

Luo, Jingrui; Wu, Ru-Shan; Gao, Fuchun

2018-06-01

In time domain, the instantaneous phase can be obtained from the complex seismic trace using Hilbert transform. The instantaneous phase information has great potential in overcoming the local minima problem and improving the result of full waveform inversion. However, the phase wrapping problem, which comes from numerical calculation, prevents its application. In order to avoid the phase wrapping problem, we choose to use the exponential phase combined with the damping method, which gives instantaneous phase-based multi-stage inversion. We construct the objective functions based on the exponential instantaneous phase, and also derive the corresponding gradient operators. Conventional full waveform inversion and the instantaneous phase-based inversion are compared with numerical examples, which indicates that in the case without low frequency information in seismic data, our method is an effective and efficient approach for initial model construction for full waveform inversion.

Efficient breaking of water/oil emulsions by a newly isolated de-emulsifying bacterium, Ochrobactrum anthropi strain RIPI5-1.

PubMed

Mohebali, Ghasemali; Kaytash, Ashk; Etemadi, Narges

2012-10-01

Water-oil emulsions occur throughout oil production, transportation, and processing. The breaking of the water/oil emulsion improves oil quality and as a consequence chemically synthesized de-emulsifiers are commonly used in the petroleum industries. Microbial de-emulsifiers represent potential alternatives to the chemicals and may become important products for petroleum industries. The main goal of this work was isolation, identification, and characterization of an efficient de-emulsifying bacterium. Following a multi-step enrichment programme a de-emulsifying bacterium, Ochrobactrum anthropi strain RIPI5-1was isolated from the oil-polluted sandy bank of Siri Island, Iran. The presence of an oil phase in growth medium was found to be unnecessary for production of the de-emulsifier. The de-emulsifying activity of both the whole culture and the cells of this strain was examined using a model multiple water-crude oil (w/o/w) emulsion. This w/o/w emulsion was used for the first time in microbial de-emulsification research. Whole cells of strain RIPI5-1 exhibited high de-emulsifying activity during the late-exponential growth and stationary phases; de-emulsifying activity of the whole culture was highest during the early-exponential growth phase. The time course of de-emulsification by whole culture and whole cells of strain RIPI5-1 was investigated; the initial rate (DeI(1)) of breaking of the multiple water-crude oil emulsion by whole culture and whole cells was calculated as 11% and 54%, respectively. However, overall de-emulsification (DeI(8.5)) for whole culture and whole cells was calculated as 63% and 72%, respectively. A clear correlation was observed between cell surface hydrophobicity and the de-emulsifying activity of whole cells. With the water/kerosene emulsion, emulsion half-life (t(1/2)) was found to be <0.5h. The potential activity of this strain was also explained using a complex oilfield emulsion. Copyright © 2012 Elsevier B.V. All rights reserved.

Proteomics Analysis of Lactobacillus casei Zhang, a New Probiotic Bacterium Isolated from Traditional Home-made Koumiss in Inner Mongolia of China*

PubMed Central

Wu, Rina; Wang, Weiwei; Yu, Dongliang; Zhang, Wenyi; Li, Yan; Sun, Zhihong; Wu, Junrui; Meng, He; Zhang, Heping

2009-01-01

Lactobacillus casei Zhang, isolated from traditional home-made koumiss in Inner Mongolia of China, was considered as a new probiotic bacterium by probiotic selection tests. We carried out a proteomics study to identify and characterize proteins expressed by L. casei Zhang in the exponential phase and stationary phase. Cytosolic proteins of the strain cultivated in de Man, Rogosa, and Sharpe broth were resolved by two-dimensional gel electrophoresis using pH 4–7 linear gradients. The number of protein spots quantified from the gels was 487 ± 21 (exponential phase) and 494 ± 13 (stationary phase) among which a total of 131 spots were identified by MALDI-TOF/MS and/or MALDI-TOF/TOF according to significant growth phase-related differences or high expression intensity proteins. Accompanied by the cluster of orthologous groups (COG), codon adaptation index (CAI), and GRAVY value analysis, the study provided a very first insight into the profile of protein expression as a reference map of L. casei. Forty-seven spots were also found in the study that showed statistically significant differences between exponential phase and stationary phase. Thirty-three of the spots increased at least 2.5-fold in the stationary phase in comparison with the exponential phase, including 19 protein spots (e.g. Hsp20, DnaK, GroEL, LuxS, pyruvate kinase, and GalU) whose intensity up-shifted above 3.0-fold. Transcriptional profiles were conducted to confirm several important differentially expressed proteins by using real time quantitative PCR. The analysis suggests that the differentially expressed proteins were mainly categorized as stress response proteins and key components of central and intermediary metabolism, indicating that these proteins might play a potential important role for the adaptation to the surroundings, especially the accumulation of lactic acid in the course of growth, and the physiological processes in bacteria cell. PMID:19508964

Hypersurface Homogeneous Cosmological Model in Modified Theory of Gravitation

NASA Astrophysics Data System (ADS)

Katore, S. D.; Hatkar, S. P.; Baxi, R. J.

2016-12-01

We study a hypersurface homogeneous space-time in the framework of the f (R, T) theory of gravitation in the presence of a perfect fluid. Exact solutions of field equations are obtained for exponential and power law volumetric expansions. We also solve the field equations by assuming the proportionality relation between the shear scalar (σ ) and the expansion scalar (θ ). It is observed that in the exponential model, the universe approaches isotropy at large time (late universe). The investigated model is notably accelerating and expanding. The physical and geometrical properties of the investigated model are also discussed.

Observational constraints on tachyonic chameleon dark energy model

NASA Astrophysics Data System (ADS)

Banijamali, A.; Bellucci, S.; Fazlpour, B.; Solbi, M.

2018-03-01

It has been recently shown that tachyonic chameleon model of dark energy in which tachyon scalar field non-minimally coupled to the matter admits stable scaling attractor solution that could give rise to the late-time accelerated expansion of the universe and hence alleviate the coincidence problem. In the present work, we use data from Type Ia supernova (SN Ia) and Baryon Acoustic oscillations to place constraints on the model parameters. In our analysis we consider in general exponential and non-exponential forms for the non-minimal coupling function and tachyonic potential and show that the scenario is compatible with observations.

Cosmological models with a hybrid scale factor in an extended gravity theory

NASA Astrophysics Data System (ADS)

Mishra, B.; Tripathy, S. K.; Tarai, Sankarsan

2018-03-01

A general formalism to investigate Bianchi type V Ih universes is developed in an extended theory of gravity. A minimally coupled geometry and matter field is considered with a rescaled function of f(R,T) substituted in place of the Ricci scalar R in the geometrical action. Dynamical aspects of the models are discussed by using a hybrid scale factor (HSF) that behaves as power law in an initial epoch and as an exponential form at late epoch. The power law behavior and the exponential behavior appear as two extreme cases of the present model.

Modeling the lag period and exponential growth of Listeria monocytogenes under conditions of fluctuating temperature and water activity values.

PubMed

Muñoz-Cuevas, Marina; Fernández, Pablo S; George, Susan; Pin, Carmen

2010-05-01

The dynamic model for the growth of a bacterial population described by Baranyi and Roberts (J. Baranyi and T. A. Roberts, Int. J. Food Microbiol. 23:277-294, 1994) was applied to model the lag period and exponential growth of Listeria monocytogenes under conditions of fluctuating temperature and water activity (a(w)) values. To model the duration of the lag phase, the dependence of the parameter h(0), which quantifies the amount of work done during the lag period, on the previous and current environmental conditions was determined experimentally. This parameter depended not only on the magnitude of the change between the previous and current environmental conditions but also on the current growth conditions. In an exponentially growing population, any change in the environment requiring a certain amount of work to adapt to the new conditions initiated a lag period that lasted until that work was finished. Observations for several scenarios in which exponential growth was halted by a sudden change in the temperature and/or a(w) were in good agreement with predictions. When a population already in a lag period was subjected to environmental fluctuations, the system was reset with a new lag phase. The work to be done during the new lag phase was estimated to be the workload due to the environmental change plus the unfinished workload from the uncompleted previous lag phase.

Proposal for a standardised identification of the mono-exponential terminal phase for orally administered drugs.

PubMed

Scheerans, Christian; Derendorf, Hartmut; Kloft, Charlotte

2008-04-01

The area under the plasma concentration-time curve from time zero to infinity (AUC(0-inf)) is generally considered to be the most appropriate measure of total drug exposure for bioavailability/bioequivalence studies of orally administered drugs. However, the lack of a standardised method for identifying the mono-exponential terminal phase of the concentration-time curve causes variability for the estimated AUC(0-inf). The present investigation introduces a simple method, called the two times t(max) method (TTT method) to reliably identify the mono-exponential terminal phase in the case of oral administration. The new method was tested by Monte Carlo simulation in Excel and compared with the adjusted r squared algorithm (ARS algorithm) frequently used in pharmacokinetic software programs. Statistical diagnostics of three different scenarios, each with 10,000 hypothetical patients showed that the new method provided unbiased average AUC(0-inf) estimates for orally administered drugs with a monophasic concentration-time curve post maximum concentration. In addition, the TTT method generally provided more precise estimates for AUC(0-inf) compared with the ARS algorithm. It was concluded that the TTT method is a most reasonable tool to be used as a standardised method in pharmacokinetic analysis especially bioequivalence studies to reliably identify the mono-exponential terminal phase for orally administered drugs showing a monophasic concentration-time profile.

Origin and Population Dynamics of a Novel HIV-1 Subtype G Clade Circulating in Cape Verde and Portugal

PubMed Central

Guimarães, Monick L.; Morgado, Mariza G.; Bello, Gonzalo

2015-01-01

The human immunodeficiency virus type 1 (HIV-1) subtype G is the most prevalent and second most prevalent HIV-1 clade in Cape Verde and Portugal, respectively; but there is no information about the origin and spatiotemporal dispersal pattern of this HIV-1 clade circulating in those countries. To this end, we used Maximum Likelihood and Bayesian coalescent-based methods to analyze a collection of 578 HIV-1 subtype G pol sequences sampled throughout Portugal, Cape Verde and 11 other countries from West and Central Africa over a period of 22 years (1992 to 2013). Our analyses indicate that most subtype G sequences from Cape Verde (80%) and Portugal (95%) branched together in a distinct monophyletic cluster (here called GCV-PT). The GCV-PT clade probably emerged after a single migration of the virus out of Central Africa into Cape Verde between the late 1970s and the middle 1980s, followed by a rapid dissemination to Portugal a couple of years later. Reconstruction of the demographic history of the GCV-PT clade circulating in Cape Verde and Portugal indicates that this viral clade displayed an initial phase of exponential growth during the 1980s and 1990s, followed by a decline in growth rate since the early 2000s. Our data also indicate that during the exponential growth phase the GCV-PT clade recombined with a preexisting subtype B viral strain circulating in Portugal, originating the CRF14_BG clade that was later disseminated to Spain and Cape Verde. Historical and recent human population movements between Angola, Cape Verde and Portugal probably played a key role in the origin and dispersal of the GCV-PT and CRF14_BG clades. PMID:25993094

Origin and Population Dynamics of a Novel HIV-1 Subtype G Clade Circulating in Cape Verde and Portugal.

PubMed

de Pina-Araujo, Isabel Inês M; Delatorre, Edson; Guimarães, Monick L; Morgado, Mariza G; Bello, Gonzalo

2015-01-01

The human immunodeficiency virus type 1 (HIV-1) subtype G is the most prevalent and second most prevalent HIV-1 clade in Cape Verde and Portugal, respectively; but there is no information about the origin and spatiotemporal dispersal pattern of this HIV-1 clade circulating in those countries. To this end, we used Maximum Likelihood and Bayesian coalescent-based methods to analyze a collection of 578 HIV-1 subtype G pol sequences sampled throughout Portugal, Cape Verde and 11 other countries from West and Central Africa over a period of 22 years (1992 to 2013). Our analyses indicate that most subtype G sequences from Cape Verde (80%) and Portugal (95%) branched together in a distinct monophyletic cluster (here called G(CV-PT)). The G(CV-PT) clade probably emerged after a single migration of the virus out of Central Africa into Cape Verde between the late 1970s and the middle 1980s, followed by a rapid dissemination to Portugal a couple of years later. Reconstruction of the demographic history of the G(CV-PT) clade circulating in Cape Verde and Portugal indicates that this viral clade displayed an initial phase of exponential growth during the 1980s and 1990s, followed by a decline in growth rate since the early 2000s. Our data also indicate that during the exponential growth phase the G(CV-PT) clade recombined with a preexisting subtype B viral strain circulating in Portugal, originating the CRF14_BG clade that was later disseminated to Spain and Cape Verde. Historical and recent human population movements between Angola, Cape Verde and Portugal probably played a key role in the origin and dispersal of the G(CV-PT )and CRF14_BG clades.

[Estimation of the time of death based on the measurements of the eye temperature in comparison with other body sites].

PubMed

Kaliszan, Michał; Hauser, Roman

2007-01-01

A systematic two-stage study was conducted in pigs to verify the models of postmortem body temperature decrease currently employed in forensic medicine. During the investigations, temperature recordings were performed in four body sites (eyeballs, orbit soft tissues, muscles and rectums). The results of the study support the possible use of the eyeball and also the orbit soft tissues as temperature measuring sites at the early phase after death; they have narrowed the significance of rectum temperature measurements to the late stage of postmortem body temperature decrease, shown insignificant correlations between the body weight and the temperature decrease rate constant and illustrated the functional increase of the time of death estimation error as the body cools, expressed in the distinct tendency to overestimate the calculated time of death as compared to the actual one. In the second stage of the experiment, a lack of a plateau phase was demonstrated, at least from 30 min post mortem. It was also found that in the very early post mortem period, the kinetics of cooling of all the body sites studied was better described by the two-exponential model than the single exponential one. The study also showed that the weak airflow present in the experimental conditions did not practically affect the course of cooling of the investigated body sites. Eyeball temperature measurements with an infra-red laser thermometer performed during the experiment proved to be of no use for determination of the time of death. The experiments allowed for defining the so far unreported value of physiological temperature of pig eyeball as 38 degrees C.

Fatty acid production in genetically modified cyanobacteria

PubMed Central

Liu, Xinyao; Sheng, Jie; Curtiss III, Roy

2011-01-01

To avoid costly biomass recovery in photosynthetic microbial biofuel production, we genetically modified cyanobacteria to produce and secrete fatty acids. Starting with introducing an acyl–acyl carrier protein thioesterase gene, we made six successive generations of genetic modifications of cyanobacterium Synechocystis sp. PCC6803 wild type (SD100). The fatty acid secretion yield was increased to 197 ± 14 mg/L of culture in one improved strain at a cell density of 1.0 × 109 cells/mL by adding codon-optimized thioesterase genes and weakening polar cell wall layers. Although these strains exhibited damaged cell membranes at low cell densities, they grew more rapidly at high cell densities in late exponential and stationary phase and exhibited less cell damage than cells in wild-type cultures. Our results suggest that fatty acid secreting cyanobacteria are a promising technology for renewable biofuel production. PMID:21482809

Probing the Production of Extreme-ultraviolet Late-phase Solar Flares Using the Model Enthalpy-based Thermal Evolution of Loops

NASA Astrophysics Data System (ADS)

Dai, Yu; Ding, Mingde

2018-04-01

Recent observations in extreme-ultraviolet (EUV) wavelengths reveal an EUV late phase in some solar flares that is characterized by a second peak in warm coronal emissions (∼3 MK) several tens of minutes to a few hours after the soft X-ray (SXR) peak. Using the model enthalpy-based thermal evolution of loops (EBTEL), we numerically probe the production of EUV late-phase solar flares. Starting from two main mechanisms of producing the EUV late phase, i.e., long-lasting cooling and secondary heating, we carry out two groups of numerical experiments to study the effects of these two processes on the emission characteristics in late-phase loops. In either of the two processes an EUV late-phase solar flare that conforms to the observational criteria can be numerically synthesized. However, the underlying hydrodynamic and thermodynamic evolutions in late-phase loops are different between the two synthetic flare cases. The late-phase peak due to a long-lasting cooling process always occurs during the radiative cooling phase, while that powered by a secondary heating is more likely to take place in the conductive cooling phase. We then propose a new method for diagnosing the two mechanisms based on the shape of EUV late-phase light curves. Moreover, from the partition of energy input, we discuss why most solar flares are not EUV late flares. Finally, by addressing some other factors that may potentially affect the loop emissions, we also discuss why the EUV late phase is mainly observed in warm coronal emissions.

Eicosanoids modulate hyperpnea-induced late phase airway obstruction and hyperreactivity in dogs.

PubMed

Davis, Michael S; McCulloch, Sharron; Myers, Teresa; Freed, Arthur N

2002-01-01

A canine model of exercise-induced asthma was used to test the hypothesis that the development of a late phase response to hyperventilation depends on the acute production of pro-inflammatory mediators. Peripheral airway resistance, reactivity to hypocapnia and aerosol histamine, and bronchoalveolar lavage fluid (BALF) cell and eicosanoid content were measured in dogs approximately 5 h after dry air challenge (DAC). DAC resulted in late phase obstruction, hyperreactivity to histamine, and neutrophilic inflammation. Both cyclooxygenase and lipoxygenase inhibitors administered in separate experiments attenuated the late phase airway obstruction and hyperreactivity to histamine. Neither drug affected the late phase inflammation nor the concentrations of eicosanoids in the BALF obtained 5 h after DAC. This study confirms that hyperventilation of peripheral airways with unconditioned air causes late phase neutrophilia, airway obstruction, and hyperreactivity. The late phase changes in airway mechanics are related to the hyperventilation-induced release of both prostaglandins and leukotrienes, and appear to be independent of the late phase infiltration of inflammatory cells.

FOG: Fighting the Achilles' Heel of Gossip Protocols with Fountain Codes

NASA Astrophysics Data System (ADS)

Champel, Mary-Luc; Kermarrec, Anne-Marie; Le Scouarnec, Nicolas

Gossip protocols are well known to provide reliable and robust dissemination protocols in highly dynamic systems. Yet, they suffer from high redundancy in the last phase of the dissemination. In this paper, we combine fountain codes (rateless erasure-correcting codes) together with gossip protocols for a robust and fast content dissemination in large-scale dynamic systems. The use of fountain enables to eliminate the unnecessary redundancy of gossip protocols. We propose the design of FOG, which fully exploits the first exponential growth phase (where the data is disseminated exponentially fast) of gossip protocols while avoiding the need for the shrinking phase by using fountain codes. FOG voluntarily increases the number of disseminations but limits those disseminations to the exponential growth phase. In addition, FOG creates a split-graph overlay that splits the peers between encoders and forwarders. Forwarder peers become encoders as soon as they have received the whole content. In order to benefit even further and quicker from encoders, FOG biases the dissemination towards the most advanced peers to make them complete earlier.

Structure of Bordetella pertussis peptidoglycan

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

Folkening, W.J.; Nogami, W.; Martin, S.A.

1987-09-01

Bordetella pertussis Tohama phases I and III were grown to the late-exponential phase in liquid medium containing (/sup 3/H)diaminopimelic acid and treated by a hot (96/sup 0/C) sodium dodecyl sulfate extraction procedure. Washed sodium dodecyl sulfate-insoluble residue from phases I and III consisted of complexes containing protein (ca. 40%) and peptidoglycan (60/sup 6/). Subsequent treatment with proteinase K yielded purified peptidoglycan which contained N-acetylglucosamine, N-acetylmuramic acid, alanine, glutamic acid, and diaminopimelic acid in molar ratios of 1:1:2:1:1 and <2% protein. Radiochemical analyses indicated that /sup 3/H added in diaminopimelic acid was present in peptidoglycan-protein complexes and purified peptidoglycan as diaminopimelicmore » acid exclusively and that pertussis peptidoglycan was not O acetylated, consistent with it being degraded completely by hen egg white lysozyme. Muramidase-derived disaccharide peptide monomers and peptide-cross-linked dimers and higher oligomers were isolated by molecular-sieve chromatography; from the distribution of these peptidoglycan fragments, the extent of peptide cross-linking of both phase I and III peptidoglycan was calculated to be ca. 48%. Unambiguous determination of the structure of muramidase-derived pepidoglycan fragments by fast atom bombardment-mass spectrometry and tandem mass spectrometry indicated that the pertussis peptidoglycan monomer fraction was surprisingly homogeneous, consisting of >95% N-acetylglucosaminyl-N-acetylmuramyl-alanyl-glutamyl-diaminopimelyl-alanine.« less

Multi-time series RNA-seq analysis of Enterobacter lignolyticus SCF1 during growth in lignin-amended medium

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

Orellana, Roberto; Chaput, Gina; Markillie, Lye Meng

The production of lignocellulosic-derived biofuels is a highly promising source of alternative energy, but it has been constrained by the lack of a microbial platform capable to efficiently degrade this recalcitrant material and cope with by-products that can be toxic to cells. Species that naturally grow in environments where carbon is mainly available as lignin are promising for finding new ways of removing the lignin that protects cellulose for improved conversion of lignin to fuel precursors. Enterobacter lignolyticus SCF1 is a facultative anaerobic Gammaproteobacteria isolated from tropical rain forest soil collected in El Yunque forest, Puerto Rico under anoxic growthmore » conditions with lignin as sole carbon source. Whole transcriptome analysis of SCF1 during E.lignolyticus SCF1 lignin degradation was conducted on cells grown in the presence (0.1%, w/w) and the absence of lignin, where samples were taken at three different times during growth, beginning of exponential phase, mid-exponential phase and beginning of stationary phase. Lignin-amended cultures achieved twice the cell biomass as unamended cultures over three days, and in this time degraded 60% of lignin. Transcripts in early exponential phase reflected this accelerated growth. A complement of laccases, aryl-alcohol dehydrogenases, and peroxidases were most up-regulated in lignin amended conditions in mid-exponential and early stationary phases compared to unamended growth. The association of hydrogen production by way of the formate hydrogenlyase complex with lignin degradation suggests a possible value added to lignin degradation in the future.« less

Multi-time series RNA-seq analysis of Enterobacter lignolyticus SCF1 during growth in lignin-amended medium.

PubMed

Orellana, Roberto; Chaput, Gina; Markillie, Lye Meng; Mitchell, Hugh; Gaffrey, Matt; Orr, Galya; DeAngelis, Kristen M

2017-01-01

The production of lignocellulosic-derived biofuels is a highly promising source of alternative energy, but it has been constrained by the lack of a microbial platform capable to efficiently degrade this recalcitrant material and cope with by-products that can be toxic to cells. Species that naturally grow in environments where carbon is mainly available as lignin are promising for finding new ways of removing the lignin that protects cellulose for improved conversion of lignin to fuel precursors. Enterobacter lignolyticus SCF1 is a facultative anaerobic Gammaproteobacteria isolated from tropical rain forest soil collected in El Yunque forest, Puerto Rico under anoxic growth conditions with lignin as sole carbon source. Whole transcriptome analysis of SCF1 during E.lignolyticus SCF1 lignin degradation was conducted on cells grown in the presence (0.1%, w/w) and the absence of lignin, where samples were taken at three different times during growth, beginning of exponential phase, mid-exponential phase and beginning of stationary phase. Lignin-amended cultures achieved twice the cell biomass as unamended cultures over three days, and in this time degraded 60% of lignin. Transcripts in early exponential phase reflected this accelerated growth. A complement of laccases, aryl-alcohol dehydrogenases, and peroxidases were most up-regulated in lignin amended conditions in mid-exponential and early stationary phases compared to unamended growth. The association of hydrogen production by way of the formate hydrogenlyase complex with lignin degradation suggests a possible value added to lignin degradation in the future.

Multi-time series RNA-seq analysis of Enterobacter lignolyticus SCF1 during growth in lignin-amended medium

PubMed Central

Chaput, Gina; Markillie, Lye Meng; Mitchell, Hugh; Gaffrey, Matt; Orr, Galya; DeAngelis, Kristen M.

2017-01-01

The production of lignocellulosic-derived biofuels is a highly promising source of alternative energy, but it has been constrained by the lack of a microbial platform capable to efficiently degrade this recalcitrant material and cope with by-products that can be toxic to cells. Species that naturally grow in environments where carbon is mainly available as lignin are promising for finding new ways of removing the lignin that protects cellulose for improved conversion of lignin to fuel precursors. Enterobacter lignolyticus SCF1 is a facultative anaerobic Gammaproteobacteria isolated from tropical rain forest soil collected in El Yunque forest, Puerto Rico under anoxic growth conditions with lignin as sole carbon source. Whole transcriptome analysis of SCF1 during E.lignolyticus SCF1 lignin degradation was conducted on cells grown in the presence (0.1%, w/w) and the absence of lignin, where samples were taken at three different times during growth, beginning of exponential phase, mid-exponential phase and beginning of stationary phase. Lignin-amended cultures achieved twice the cell biomass as unamended cultures over three days, and in this time degraded 60% of lignin. Transcripts in early exponential phase reflected this accelerated growth. A complement of laccases, aryl-alcohol dehydrogenases, and peroxidases were most up-regulated in lignin amended conditions in mid-exponential and early stationary phases compared to unamended growth. The association of hydrogen production by way of the formate hydrogenlyase complex with lignin degradation suggests a possible value added to lignin degradation in the future. PMID:29049419

Multi-time series RNA-seq analysis of Enterobacter lignolyticus SCF1 during growth in lignin-amended medium

DOE PAGES

Orellana, Roberto; Chaput, Gina; Markillie, Lye Meng; ...

2017-10-19

The production of lignocellulosic-derived biofuels is a highly promising source of alternative energy, but it has been constrained by the lack of a microbial platform capable to efficiently degrade this recalcitrant material and cope with by-products that can be toxic to cells. Species that naturally grow in environments where carbon is mainly available as lignin are promising for finding new ways of removing the lignin that protects cellulose for improved conversion of lignin to fuel precursors. Enterobacter lignolyticus SCF1 is a facultative anaerobic Gammaproteobacteria isolated from tropical rain forest soil collected in El Yunque forest, Puerto Rico under anoxic growthmore » conditions with lignin as sole carbon source. Whole transcriptome analysis of SCF1 during E.lignolyticus SCF1 lignin degradation was conducted on cells grown in the presence (0.1%, w/w) and the absence of lignin, where samples were taken at three different times during growth, beginning of exponential phase, mid-exponential phase and beginning of stationary phase. Lignin-amended cultures achieved twice the cell biomass as unamended cultures over three days, and in this time degraded 60% of lignin. Transcripts in early exponential phase reflected this accelerated growth. A complement of laccases, aryl-alcohol dehydrogenases, and peroxidases were most up-regulated in lignin amended conditions in mid-exponential and early stationary phases compared to unamended growth. The association of hydrogen production by way of the formate hydrogenlyase complex with lignin degradation suggests a possible value added to lignin degradation in the future.« less

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

Zhou, Quanlin; Oldenburg, Curtis M.; Spangler, Lee H.

Analytical solutions with infinite exponential series are available to calculate the rate of diffusive transfer between low-permeability blocks and high-permeability zones in the subsurface. Truncation of these series is often employed by neglecting the early-time regime. Here in this paper, we present unified-form approximate solutions in which the early-time and the late-time solutions are continuous at a switchover time. The early-time solutions are based on three-term polynomial functions in terms of square root of dimensionless time, with the first coefficient dependent only on the dimensionless area-to-volume ratio. The last two coefficients are either determined analytically for isotropic blocks (e.g., spheresmore » and slabs) or obtained by fitting the exact solutions, and they solely depend on the aspect ratios for rectangular columns and parallelepipeds. For the late-time solutions, only the leading exponential term is needed for isotropic blocks, while a few additional exponential terms are needed for highly anisotropic rectangular blocks. The optimal switchover time is between 0.157 and 0.229, with highest relative approximation error less than 0.2%. The solutions are used to demonstrate the storage of dissolved CO 2 in fractured reservoirs with low-permeability matrix blocks of single and multiple shapes and sizes. These approximate solutions are building blocks for development of analytical and numerical tools for hydraulic, solute, and thermal diffusion processes in low-permeability matrix blocks.« less

Is it growing exponentially fast? -- Impact of assuming exponential growth for characterizing and forecasting epidemics with initial near-exponential growth dynamics.

PubMed

Chowell, Gerardo; Viboud, Cécile

2016-10-01

The increasing use of mathematical models for epidemic forecasting has highlighted the importance of designing models that capture the baseline transmission characteristics in order to generate reliable epidemic forecasts. Improved models for epidemic forecasting could be achieved by identifying signature features of epidemic growth, which could inform the design of models of disease spread and reveal important characteristics of the transmission process. In particular, it is often taken for granted that the early growth phase of different growth processes in nature follow early exponential growth dynamics. In the context of infectious disease spread, this assumption is often convenient to describe a transmission process with mass action kinetics using differential equations and generate analytic expressions and estimates of the reproduction number. In this article, we carry out a simulation study to illustrate the impact of incorrectly assuming an exponential-growth model to characterize the early phase (e.g., 3-5 disease generation intervals) of an infectious disease outbreak that follows near-exponential growth dynamics. Specifically, we assess the impact on: 1) goodness of fit, 2) bias on the growth parameter, and 3) the impact on short-term epidemic forecasts. Designing transmission models and statistical approaches that more flexibly capture the profile of epidemic growth could lead to enhanced model fit, improved estimates of key transmission parameters, and more realistic epidemic forecasts.

Induction of a global stress response during the first step of Escherichia coli plate growth.

PubMed

Cuny, Caroline; Lesbats, Maïalène; Dukan, Sam

2007-02-01

We have investigated the first events that occur when exponentially grown cells are transferred from a liquid medium (Luria-Bertani [LB]) to a solid medium (LB agar [LBA]). We observed an initial lag phase of 180 min for the wild type MG1655 without any apparent growth. This lack of growth was independent of the bacterial physiological state (either the stationary or the exponential phase), the solid medium composition, or the number of cells on the plate, but it was dependent on the bacterial genotype. Using lacZ-reporter fusions and two-dimensional electrophoresis analysis, we observed that when cells from exponential-phase cultures were plated on LBA, several global regulons, like heat shock regulons (RpoH, RpoE, CpxAR) and oxidative-stress regulons (SoxRS, OxyR, Fur), were immediately induced. Our results indicate that in order to grow on plates, bacteria must not only adapt to new conditions but also perceive a real stress.

A high-energy-density, high-Mach number single jet experiment

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

Hansen, J. F.; Dittrich, T. R.; Elliott, J. B.

2011-08-15

A high-energy-density, x-ray-driven, high-Mach number (M{>=} 17) single jet experiment shows constant propagation speeds of the jet and its bowshock into the late time regime. The jet assumes a characteristic mushroom shape with a stalk and a head. The width of the head and the bowshock also grow linearly in time. The width of the stalk decreases exponentially toward an asymptotic value. In late time images, the stalk kinks and develops a filamentary nature, which is similar to experiments with applied magnetic fields. Numerical simulations match the experiment reasonably well, but ''exterior'' details of the laser target must be includedmore » to obtain a match at late times.« less

Quantitation of bacteria through adsorption of intracellular biomolecules on carbon paste and screen-printed carbon electrodes and voltammetry of redox-active probes.

PubMed

Obuchowska, Agnes

2008-03-01

A new electrochemical method for the quantitation of bacteria that is rapid, inexpensive, and amenable to miniaturization is reported. Cyclic voltammetry was used to quantitate M. luteus, C. sporogenes, and E. coli JM105 in exponential and stationary phases, following exposure of screen-printed carbon working electrodes (SPCEs) to lysed culture samples. Ferricyanide was used as a probe. The detection limits (3s) were calculated and the dynamic ranges for E. coli (exponential and stationary phases), M. luteus (exponential and stationary phases), and C. sporogenes (exponential phase) lysed by lysozyme were 3 x 10(4) to 5 x 10(6) colony-forming units (CFU) mL(-1), 5 x 10(6) to 2 x 10(8) CFU mL(-1) and 3 x 10(3) to 3 x 10(5) CFU mL(-1), respectively. Good overlap was obtained between the calibration curves when the electrochemical signal was plotted against the dry bacterial weight, or between the protein concentration in the bacterial lysate. In contrast, unlysed bacteria did not change the electrochemical signal of ferricyanide. The results indicate that the reduction of the electrochemical signal in the presence of the lysate is mainly due to the fouling of the electrode by proteins. Similar results were obtained with carbon-paste electrodes although detection limits were better with SPCEs. The method described herein was applied to quantitation of bacteria in a cooling tower water sample.

Thermodynamics and glassy phase transition of regular black holes

NASA Astrophysics Data System (ADS)

Javed, Wajiha; Yousaf, Z.; Akhtar, Zunaira

2018-05-01

This paper is aimed to study thermodynamical properties of phase transition for regular charged black holes (BHs). In this context, we have considered two different forms of BH metrics supplemented with exponential and logistic distribution functions and investigated the recent expansion of phase transition through grand canonical ensemble. After exploring the corresponding Ehrenfest’s equation, we found the second-order background of phase transition at critical points. In order to check the critical behavior of regular BHs, we have evaluated some corresponding explicit relations for the critical temperature, pressure and volume and draw certain graphs with constant values of Smarr’s mass. We found that for the BH metric with exponential configuration function, the phase transition curves are divergent near the critical points, while glassy phase transition has been observed for the Ayón-Beato-García-Bronnikov (ABGB) BH in n = 5 dimensions.

Paradoxical physiological transitions from aging to late life in Drosophila.

PubMed

Shahrestani, Parvin; Quach, Julie; Mueller, Laurence D; Rose, Michael R

2012-02-01

In a variety of organisms, adulthood is divided into aging and late life, where aging is a period of exponentially increasing mortality rates and late life is a period of roughly plateaued mortality rates. In this study we used ∼57,600 Drosophila melanogaster from six replicate populations to examine the physiological transitions from aging to late life in four functional characters that decline during aging: desiccation resistance, starvation resistance, time spent in motion, and negative geotaxis. Time spent in motion and desiccation resistance declined less quickly in late life compared to their patterns of decline during aging. Negative geotaxis declined at a faster rate in late life compared to its rate of decline during aging. These results yield two key findings: (1) Late-life physiology is distinct from the physiology of aging, in that there is not simply a continuation of the physiological trends which characterize aging; and (2) late life physiology is complex, in that physiological characters vary with respect to their stabilization, deceleration, or acceleration in the transition from aging to late life. These findings imply that a correct understanding of adulthood requires identifying and appropriately characterizing physiology during properly delimited late-life periods as well as aging periods.

Paradoxical Physiological Transitions from Aging to Late Life in Drosophila

PubMed Central

Quach, Julie; Mueller, Laurence D.; Rose, Michael R.

2012-01-01

Abstract In a variety of organisms, adulthood is divided into aging and late life, where aging is a period of exponentially increasing mortality rates and late life is a period of roughly plateaued mortality rates. In this study we used ∼57,600 Drosophila melanogaster from six replicate populations to examine the physiological transitions from aging to late life in four functional characters that decline during aging: desiccation resistance, starvation resistance, time spent in motion, and negative geotaxis. Time spent in motion and desiccation resistance declined less quickly in late life compared to their patterns of decline during aging. Negative geotaxis declined at a faster rate in late life compared to its rate of decline during aging. These results yield two key findings: (1) Late-life physiology is distinct from the physiology of aging, in that there is not simply a continuation of the physiological trends which characterize aging; and (2) late life physiology is complex, in that physiological characters vary with respect to their stabilization, deceleration, or acceleration in the transition from aging to late life. These findings imply that a correct understanding of adulthood requires identifying and appropriately characterizing physiology during properly delimited late-life periods as well as aging periods. PMID:22233126

Genuine cosmic hair

NASA Astrophysics Data System (ADS)

Kastor, David; Ray, Sourya; Traschen, Jennie

2017-02-01

We show that asymptotically future de Sitter (AFdS) spacetimes carry ‘genuine’ cosmic hair; information that is analogous to the mass and angular momentum of asymptotically flat spacetimes and that characterizes how an AFdS spacetime approaches its asymptotic form. We define new ‘cosmological tension’ charges associated with future asymptotic spatial translation symmetries, which are analytic continuations of the ADM mass and tensions of asymptotically planar AdS spacetimes, and which measure the leading anisotropic corrections to the isotropic, exponential de Sitter expansion rate. A cosmological Smarr relation, holding for AFdS spacetimes having exact spatial translation symmetry, is derived. This formula relates cosmological tension, which is evaluated at future infinity, to properties of the cosmology at early times, together with a ‘cosmological volume’ contribution that is analogous to the thermodynamic volume of AdS black holes. Smarr relations for different spatial directions imply that the difference in expansion rates between two directions at late times is related in a simple way to their difference at early times. Hence information about the very early universe can be inferred from cosmic hair, which is potentially observable in a late time de Sitter phase. Cosmological tension charges and related quantities are evaluated for Kasner-de Sitter spacetimes, which serve as our primary examples.

2D CFT partition functions at late times

NASA Astrophysics Data System (ADS)

Dyer, Ethan; Gur-Ari, Guy

2017-08-01

We consider the late time behavior of the analytically continued partition function Z( β + it) Z( β - it) in holographic 2 d CFTs. This is a probe of information loss in such theories and in their holographic duals. We show that each Virasoro character decays in time, and so information is not restored at the level of individual characters. We identify a universal decaying contribution at late times, and conjecture that it describes the behavior of generic chaotic 2 d CFTs out to times that are exponentially large in the central charge. It was recently suggested that at sufficiently late times one expects a crossover to random matrix behavior. We estimate an upper bound on the crossover time, which suggests that the decay is followed by a parametrically long period of late time growth. Finally, we discuss gravitationally-motivated integrable theories and show how information is restored at late times by a series of characters. This hints at a possible bulk mechanism, where information is restored by an infinite sum over non-perturbative saddles.

Simultaneous estimation of multiple phases in digital holographic interferometry using state space analysis

NASA Astrophysics Data System (ADS)

Kulkarni, Rishikesh; Rastogi, Pramod

2018-05-01

A new approach is proposed for the multiple phase estimation from a multicomponent exponential phase signal recorded in multi-beam digital holographic interferometry. It is capable of providing multidimensional measurements in a simultaneous manner from a single recording of the exponential phase signal encoding multiple phases. Each phase within a small window around each pixel is appproximated with a first order polynomial function of spatial coordinates. The problem of accurate estimation of polynomial coefficients, and in turn the unwrapped phases, is formulated as a state space analysis wherein the coefficients and signal amplitudes are set as the elements of a state vector. The state estimation is performed using the extended Kalman filter. An amplitude discrimination criterion is utilized in order to unambiguously estimate the coefficients associated with the individual signal components. The performance of proposed method is stable over a wide range of the ratio of signal amplitudes. The pixelwise phase estimation approach of the proposed method allows it to handle the fringe patterns that may contain invalid regions.

A review on the structural styles of deformation during Late Cretaceous and Paleocene tectonic phases in the southern North Sea area

NASA Astrophysics Data System (ADS)

Deckers, Jef; van der Voet, Eva

2018-04-01

The Mesozoic rifts in the southern North Sea area were affected by Late Cretaceous to Paleocene inversion. Two main inversion phases were traditionally identified in this interval: the Sub-Hercynian and the Laramide phases. The Sub-Hercynian phase started in the early Late Cretaceous, peaked during the Campanian and ended in the late Maastrichtian, while the Laramide phase started in the late Danian and ended in the Thanetian. The Late Cretaceous Sub-Hercynian phase was strong and occurred in several pulses. These pulses led to basin-scale uplift by large reverse movements along basin-bounding faults and resulted in large amounts of erosion (up to 2 km) of Mesozoic and older sediments. The middle Paleocene Laramide phase on the other hand resulted in mild, domal uplift of some Late Cretaceous inverted basins and subsidence (into depocenters) of others. The subsequent Cenozoic inversion phases displayed similar or lower amplitudes and wavelengths of vertical surface movements as the Laramide phase. The transition from the Sub-Hercynian to the Laramide phase in the southern North Sea area therefore coincides with the overall transition from fault-controlled inversion to broad domal vertical surface movements.

A comparison of modelling techniques used to characterise oxygen uptake kinetics during the on-transient of exercise.

PubMed

Bell, C; Paterson, D H; Kowalchuk, J M; Padilla, J; Cunningham, D A

2001-09-01

We compared estimates for the phase 2 time constant (tau) of oxygen uptake (VO2) during moderate- and heavy-intensity exercise, and the slow component of VO2 during heavy-intensity exercise using previously published exponential models. Estimates for tau and the slow component were different (P < 0.05) among models. For moderate-intensity exercise, a two-component exponential model, or a mono-exponential model fitted from 20 s to 3 min were best. For heavy-intensity exercise, a three-component model fitted throughout the entire 6 min bout of exercise, or a two-component model fitted from 20 s were best. When the time delays for the two- and three-component models were equal the best statistical fit was obtained; however, this model produced an inappropriately low DeltaVO2/DeltaWR (WR, work rate) for the projected phase 2 steady state, and the estimate of phase 2 tau was shortened compared with other models. The slow component was quantified as the difference between VO2 at end-exercise (6 min) and at 3 min (DeltaVO2 (6-3 min)); 259 ml x min(-1)), and also using the phase 3 amplitude terms (truncated to end-exercise) from exponential fits (409-833 ml x min(-1)). Onset of the slow component was identified by the phase 3 time delay parameter as being of delayed onset approximately 2 min (vs. arbitrary 3 min). Using this delay DeltaVO2 (6-2 min) was approximately 400 ml x min(-1). Use of valid consistent methods to estimate tau and the slow component in exercise are needed to advance physiological understanding.

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2001-05-15

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Analog detection for cavity lifetime spectroscopy

DOEpatents

Zare, Richard N.; Harb, Charles C.; Paldus, Barbara A.; Spence, Thomas G.

2003-01-01

An analog detection system for determining a ring-down rate or decay rate 1/.tau. of an exponentially decaying ring-down beam issuing from a lifetime or ring-down cavity during a ring-down phase. Alternatively, the analog detection system determines a build-up rate of an exponentially growing beam issuing from the cavity during a ring-up phase. The analog system can be employed in continuous wave cavity ring-down spectroscopy (CW CRDS) and pulsed CRDS (P CRDS) arrangements utilizing any type of ring-down cavity including ring-cavities and linear cavities.

Coaggregation between Rhodococcus and Acinetobacter strains isolated from the food industry.

PubMed

Møretrø, Trond; Sharifzadeh, Shahab; Langsrud, Solveig; Heir, Even; Rickard, Alexander H

2015-07-01

In this study, coaggregation interactions between Rhodococcus and Acinetobacter strains isolated from food-processing surfaces were characterized. Rhodococcus sp. strain MF3727 formed intrageneric coaggregates with Rhodococcus sp. strain MF3803 and intergeneric coaggregates with 2 strains of Acinetobacter calcoaceticus (MF3293, MF3627). Stronger coaggregation between A. calcoaceticus MF3727 and Rhodococcus sp. MF3293 was observed after growth in batch culture at 30 °C than at 20 °C, after growth in tryptic soy broth than in liquid R2A medium, and between cells in exponential and early stationary phases than cells in late stationary phase. The coaggregation ability of Rhodococcus sp. MF3727 was maintained even after heat and Proteinase K treatment, suggesting its ability to coaggregate was protein independent whereas the coaggregation determinants of the other strains involved proteinaceous cell-surface-associated polymers. Coaggregation was stable at pH 5-9. The mechanisms of coaggregation among Acinetobacter and Rhodococcus strains bare similarity to those displayed by coaggregating bacteria of oral and freshwater origin, with respect to binding between proteinaceous and nonproteinaceous determinants and the effect of environmental factors on coaggregation. Coaggregation may contribute to biofilm formation on industrial food surfaces, protecting bacteria against cleaning and disinfection.

Expression of the genes for insecticidal crystal proteins in Bacillus thuringiensis: cryIVA, not cryIVB, is transcribed by RNA polymerase containing sigma H and that containing sigma E.

PubMed

Yoshisue, H; Ihara, K; Nishimoto, T; Sakai, H; Komano, T

1995-03-15

To investigate the mechanism of transcriptional regulation of cryIVA and cryIVB, encoding 130-kDa dipteran-active crystal proteins, in Bacillus thuringiensis subsp. israelensis, we introduced each gene into several sporulation mutants of Bacillus subtilis. A spoIIG mutation, the wild-type gene of which encodes sigma E precursor, completely blocked the cryIVB transcription. In contrast, low but detectable transcription of cryIVA was observed in the spoIIG mutant. In the wild-type B. subtilis, no transcription of cryIVB was detected before T2 (2 h after the onset of stationary phase), while the cryIVA transcription started at the late exponential phase at low levels. Furthermore, in a wild-type strain of B. thuringiensis subsp. israelensis, transcription of cryIVA began earlier than that of genes encoding other crystal components, cryIVB and cytA. A consensus sequence recognized by an RNA polymerase containing sigma H of B. subtilis was found upstream of the transcription start point of cryIVA, which overlapped with that recognized by sigma E.

On information loss in AdS 3/CFT 2

DOE PAGES

Fitzpatrick, A. Liam; Kaplan, Jared; Li, Daliang; ...

2016-05-18

We discuss information loss from black hole physics in AdS 3, focusing on two sharp signatures infecting CFT 2 correlators at large central charge c: ‘forbidden singularities’ arising from Euclidean-time periodicity due to the effective Hawking temperature, and late-time exponential decay in the Lorentzian region. We study an infinite class of examples where forbidden singularities can be resolved by non-perturbative effects at finite c, and we show that the resolution has certain universal features that also apply in the general case. Analytically continuing to the Lorentzian regime, we find that the non-perturbative effects that resolve forbidden singularities qualitatively change themore » behavior of correlators at times t ~S BH, the black hole entropy. This may resolve the exponential decay of correlators at late times in black hole backgrounds. By Borel resumming the 1/c expansion of exact examples, we explicitly identify ‘information-restoring’ effects from heavy states that should correspond to classical solutions in AdS 3. Lastly, our results suggest a line of inquiry towards a more precise formulation of the gravitational path integral in AdS 3.« less

Approximate solutions for diffusive fracture-matrix transfer: Application to storage of dissolved CO 2 in fractured rocks

DOE PAGES

Zhou, Quanlin; Oldenburg, Curtis M.; Spangler, Lee H.; ...

2017-01-05

Analytical solutions with infinite exponential series are available to calculate the rate of diffusive transfer between low-permeability blocks and high-permeability zones in the subsurface. Truncation of these series is often employed by neglecting the early-time regime. Here in this paper, we present unified-form approximate solutions in which the early-time and the late-time solutions are continuous at a switchover time. The early-time solutions are based on three-term polynomial functions in terms of square root of dimensionless time, with the first coefficient dependent only on the dimensionless area-to-volume ratio. The last two coefficients are either determined analytically for isotropic blocks (e.g., spheresmore » and slabs) or obtained by fitting the exact solutions, and they solely depend on the aspect ratios for rectangular columns and parallelepipeds. For the late-time solutions, only the leading exponential term is needed for isotropic blocks, while a few additional exponential terms are needed for highly anisotropic rectangular blocks. The optimal switchover time is between 0.157 and 0.229, with highest relative approximation error less than 0.2%. The solutions are used to demonstrate the storage of dissolved CO 2 in fractured reservoirs with low-permeability matrix blocks of single and multiple shapes and sizes. These approximate solutions are building blocks for development of analytical and numerical tools for hydraulic, solute, and thermal diffusion processes in low-permeability matrix blocks.« less

On the Importance of the Flare's Late Phase for the Solar Extreme Ultraviolet Irradiance

NASA Technical Reports Server (NTRS)

Woods, Thomas N.; Eparvier, Frank; Jones, Andrew R.; Hock, Rachel; Chamberlin, Phillip C.; Klimchuk, James A.; Didkovsky, Leonid; Judge, Darrell; Mariska, John; Bailey, Scott;

Low intensity infrared laser induces filamentation in Escherichia coli cells

NASA Astrophysics Data System (ADS)

Fonseca, A. S.; Presta, G. A.; Geller, M.; Paoli, F.

2011-10-01

Low intensity continuous wave and pulsed emission modes laser is used in treating many diseases and the resulting biostimulative effect on tissues has been described, yet the photobiological basis is not well understood. The aim of this wok was to evaluate, using bacterial filamentation assay, effects of laser on Escherichia coli cultures in exponential and stationary growth phase. E. coli cultures, proficient and deficient on DNA repair, in exponential and stationary growth phase, were exposed to low intensity infrared laser, aliquots were spread onto microscopic slides, stained by Gram method, visualized by optical microscopy, photographed and percentage of bacterial filamentation were determined. Low intensity infrared laser with therapeutic fluencies and different emission modes can induce bacterial filamentation in cultures of E. coli wild type, fpg/ mutM, endonuclease III and exonuclease III mutants in exponential and stationary growth phase. This study showed induction of bacterial, filamentation in E. coli cultures expose to low intensity infrared laser and attention to laser therapy protocols, which should take into account fluencies, wavelengths, tissue conditions, and genetic characteristics of cells before beginning treatment.

Effect of local minima on adiabatic quantum optimization.

PubMed

Amin, M H S

2008-04-04

We present a perturbative method to estimate the spectral gap for adiabatic quantum optimization, based on the structure of the energy levels in the problem Hamiltonian. We show that, for problems that have an exponentially large number of local minima close to the global minimum, the gap becomes exponentially small making the computation time exponentially long. The quantum advantage of adiabatic quantum computation may then be accessed only via the local adiabatic evolution, which requires phase coherence throughout the evolution and knowledge of the spectrum. Such problems, therefore, are not suitable for adiabatic quantum computation.

Bacterial genomes lacking long-range correlations may not be modeled by low-order Markov chains: the role of mixing statistics and frame shift of neighboring genes.

PubMed

Cocho, Germinal; Miramontes, Pedro; Mansilla, Ricardo; Li, Wentian

2014-12-01

We examine the relationship between exponential correlation functions and Markov models in a bacterial genome in detail. Despite the well known fact that Markov models generate sequences with correlation function that decays exponentially, simply constructed Markov models based on nearest-neighbor dimer (first-order), trimer (second-order), up to hexamer (fifth-order), and treating the DNA sequence as being homogeneous all fail to predict the value of exponential decay rate. Even reading-frame-specific Markov models (both first- and fifth-order) could not explain the fact that the exponential decay is very slow. Starting with the in-phase coding-DNA-sequence (CDS), we investigated correlation within a fixed-codon-position subsequence, and in artificially constructed sequences by packing CDSs with out-of-phase spacers, as well as altering CDS length distribution by imposing an upper limit. From these targeted analyses, we conclude that the correlation in the bacterial genomic sequence is mainly due to a mixing of heterogeneous statistics at different codon positions, and the decay of correlation is due to the possible out-of-phase between neighboring CDSs. There are also small contributions to the correlation from bases at the same codon position, as well as by non-coding sequences. These show that the seemingly simple exponential correlation functions in bacterial genome hide a complexity in correlation structure which is not suitable for a modeling by Markov chain in a homogeneous sequence. Other results include: use of the (absolute value) second largest eigenvalue to represent the 16 correlation functions and the prediction of a 10-11 base periodicity from the hexamer frequencies. Copyright © 2014 Elsevier Ltd. All rights reserved.

Pore‐Scale Hydrodynamics in a Progressively Bioclogged Three‐Dimensional Porous Medium: 3‐D Particle Tracking Experiments and Stochastic Transport Modeling

PubMed Central

Carrel, M.; Dentz, M.; Derlon, N.; Morgenroth, E.

2018-01-01

Abstract Biofilms are ubiquitous bacterial communities that grow in various porous media including soils, trickling, and sand filters. In these environments, they play a central role in services ranging from degradation of pollutants to water purification. Biofilms dynamically change the pore structure of the medium through selective clogging of pores, a process known as bioclogging. This affects how solutes are transported and spread through the porous matrix, but the temporal changes to transport behavior during bioclogging are not well understood. To address this uncertainty, we experimentally study the hydrodynamic changes of a transparent 3‐D porous medium as it experiences progressive bioclogging. Statistical analyses of the system's hydrodynamics at four time points of bioclogging (0, 24, 36, and 48 h in the exponential growth phase) reveal exponential increases in both average and variance of the flow velocity, as well as its correlation length. Measurements for spreading, as mean‐squared displacements, are found to be non‐Fickian and more intensely superdiffusive with progressive bioclogging, indicating the formation of preferential flow pathways and stagnation zones. A gamma distribution describes well the Lagrangian velocity distributions and provides parameters that quantify changes to the flow, which evolves from a parallel pore arrangement under unclogged conditions, toward a more serial arrangement with increasing clogging. Exponentially evolving hydrodynamic metrics agree with an exponential bacterial growth phase and are used to parameterize a correlated continuous time random walk model with a stochastic velocity relaxation. The model accurately reproduces transport observations and can be used to resolve transport behavior at intermediate time points within the exponential growth phase considered. PMID:29780184

Pore-Scale Hydrodynamics in a Progressively Bioclogged Three-Dimensional Porous Medium: 3-D Particle Tracking Experiments and Stochastic Transport Modeling

NASA Astrophysics Data System (ADS)

Carrel, M.; Morales, V. L.; Dentz, M.; Derlon, N.; Morgenroth, E.; Holzner, M.

2018-03-01

Biofilms are ubiquitous bacterial communities that grow in various porous media including soils, trickling, and sand filters. In these environments, they play a central role in services ranging from degradation of pollutants to water purification. Biofilms dynamically change the pore structure of the medium through selective clogging of pores, a process known as bioclogging. This affects how solutes are transported and spread through the porous matrix, but the temporal changes to transport behavior during bioclogging are not well understood. To address this uncertainty, we experimentally study the hydrodynamic changes of a transparent 3-D porous medium as it experiences progressive bioclogging. Statistical analyses of the system's hydrodynamics at four time points of bioclogging (0, 24, 36, and 48 h in the exponential growth phase) reveal exponential increases in both average and variance of the flow velocity, as well as its correlation length. Measurements for spreading, as mean-squared displacements, are found to be non-Fickian and more intensely superdiffusive with progressive bioclogging, indicating the formation of preferential flow pathways and stagnation zones. A gamma distribution describes well the Lagrangian velocity distributions and provides parameters that quantify changes to the flow, which evolves from a parallel pore arrangement under unclogged conditions, toward a more serial arrangement with increasing clogging. Exponentially evolving hydrodynamic metrics agree with an exponential bacterial growth phase and are used to parameterize a correlated continuous time random walk model with a stochastic velocity relaxation. The model accurately reproduces transport observations and can be used to resolve transport behavior at intermediate time points within the exponential growth phase considered.

Shift-Invariant Image Reconstruction of Speckle-Degraded Images Using Bispectrum Estimation

DTIC Science & Technology

1990-05-01

process with the requisite negative exponential pelf. I call this model the Negative Exponential Model ( NENI ). The NENI flowchart is seen in Figure 6...Figure ]3d-g. Statistical Histograms and Phase for the RPj NG EXP FDF MULT METHOD FILuteC 14a. Truth Object Speckled Via the NENI HISTOGRAM OF SPECKLE

Application of a Short Intracellular pH Method to Flow Cytometry for Determining Saccharomyces cerevisiae Vitality ▿

PubMed Central

Weigert, Claudia; Steffler, Fabian; Kurz, Tomas; Shellhammer, Thomas H.; Methner, Frank-Jürgen

2009-01-01

The measurement of yeast's intracellular pH (ICP) is a proven method for determining yeast vitality. Vitality describes the condition or health of viable cells as opposed to viability, which defines living versus dead cells. In contrast to fluorescence photometric measurements, which show only average ICP values of a population, flow cytometry allows the presentation of an ICP distribution. By examining six repeated propagations with three separate growth phases (lag, exponential, and stationary), the ICP method previously established for photometry was transferred successfully to flow cytometry by using the pH-dependent fluorescent probe 5,6-carboxyfluorescein. The correlation between the two methods was good (r2 = 0.898, n = 18). With both methods it is possible to track the course of growth phases. Although photometry did not yield significant differences between exponentially and stationary phases (P = 0.433), ICP via flow cytometry did (P = 0.012). Yeast in an exponential phase has a unimodal ICP distribution, reflective of a homogeneous population; however, yeast in a stationary phase displays a broader ICP distribution, and subpopulations could be defined by using the flow cytometry method. In conclusion, flow cytometry yielded specific evidence of the heterogeneity in vitality of a yeast population as measured via ICP. In contrast to photometry, flow cytometry increases information about the yeast population's vitality via a short measurement, which is suitable for routine analysis. PMID:19581482

Stochastic scheduling on a repairable manufacturing system

NASA Astrophysics Data System (ADS)

Li, Wei; Cao, Jinhua

1995-08-01

In this paper, we consider some stochastic scheduling problems with a set of stochastic jobs on a manufacturing system with a single machine that is subject to multiple breakdowns and repairs. When the machine processing a job fails, the job processing must restart some time later when the machine is repaired. For this typical manufacturing system, we find the optimal policies that minimize the following objective functions: (1) the weighed sum of the completion times; (2) the weighed number of late jobs having constant due dates; (3) the weighted number of late jobs having random due dates exponentially distributed, which generalize some previous results.

Inhibition of the sodium-translocating NADH-ubiquinone oxidoreductase [Na+-NQR] decreases cholera toxin production in Vibrio cholerae O1 at the late exponential growth phase

PubMed Central

Minato, Yusuke; Fassio, Sara R.; Reddekopp, Rylan L.; Häse, Claudia C.

2014-01-01

Two virulence factors produced by Vibrio cholerae, cholera toxin (CT) and toxin-corregulated pilus (TCP), are indispensable for cholera infection. ToxT is the central regulatory protein involved in activation of CT and TCP expression. We previously reported that lack of a respiration-linked sodium-translocating NADH–ubiquinone oxidoreductase (Na+-NQR) significantly increases toxT transcription. In this study, we further characterized this link and found that Na+-NQR affects toxT expression only at the early-log growth phase, whereas lack of Na+-NQR decreases CT production after the mid-log growth phase. Such decreased CT production was independent of toxT and ctxB transcription. Supplementing a respiratory substrate, L-lactate, into the growth media restored CT production in the nqrA-F mutant, suggesting that decreased CT production in the Na+-NQR mutant is dependent on electron transport chain (ETC) activity. This notion was supported by the observations that two chemical inhibitors, a Na+-NQR specific inhibitor 2-n-Heptyl-4-hydroxyquinoline N-oxide (HQNO) and a succinate dehydrogenase (SDH) inhibitor, thenoyltrifluoroacetone (TTFA), strongly inhibited CT production in both classical and El Tor biotype strains of V. cholerae. Accordingly, we propose the main respiratory enzyme of V. cholerae, as a potential drug target to treat cholera because human mitochondria do not contain Na+-NQR orthologs. PMID:24361395

Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

USGS Publications Warehouse

Bohu, Tsing; Santelli, Cara M; Akob, Denise M.; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

2015-01-01

Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1.

PubMed

Bohu, Tsing; Santelli, Cara M; Akob, Denise M; Neu, Thomas R; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

2015-01-01

Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling.

Validation of Reference Genes for Real-Time Quantitative PCR (qPCR) Analysis of Avibacterium paragallinarum.

PubMed

Wen, Shuxiang; Chen, Xiaoling; Xu, Fuzhou; Sun, Huiling

2016-01-01

Real-time quantitative reverse transcription PCR (qRT-PCR) offers a robust method for measurement of gene expression levels. Selection of reliable reference gene(s) for gene expression study is conducive to reduce variations derived from different amounts of RNA and cDNA, the efficiency of the reverse transcriptase or polymerase enzymes. Until now reference genes identified for other members of the family Pasteurellaceae have not been validated for Avibacterium paragallinarum. The aim of this study was to validate nine reference genes of serovars A, B, and C strains of A. paragallinarum in different growth phase by qRT-PCR. Three of the most widely used statistical algorithms, geNorm, NormFinder and ΔCT method were used to evaluate the expression stability of reference genes. Data analyzed by overall rankings showed that in exponential and stationary phase of serovar A, the most stable reference genes were gyrA and atpD respectively; in exponential and stationary phase of serovar B, the most stable reference genes were atpD and recN respectively; in exponential and stationary phase of serovar C, the most stable reference genes were rpoB and recN respectively. This study provides recommendations for stable endogenous control genes for use in further studies involving measurement of gene expression levels.

Accounting for inherent variability of growth in microbial risk assessment.

PubMed

Marks, H M; Coleman, M E

2005-04-15

Risk assessments of pathogens need to account for the growth of small number of cells under varying conditions. In order to determine the possible risks that occur when there are small numbers of cells, stochastic models of growth are needed that would capture the distribution of the number of cells over replicate trials of the same scenario or environmental conditions. This paper provides a simple stochastic growth model, accounting only for inherent cell-growth variability, assuming constant growth kinetic parameters, for an initial, small, numbers of cells assumed to be transforming from a stationary to an exponential phase. Two, basic, microbial sets of assumptions are considered: serial, where it is assume that cells transform through a lag phase before entering the exponential phase of growth; and parallel, where it is assumed that lag and exponential phases develop in parallel. The model is based on, first determining the distribution of the time when growth commences, and then modelling the conditional distribution of the number of cells. For the latter distribution, it is found that a Weibull distribution provides a simple approximation to the conditional distribution of the relative growth, so that the model developed in this paper can be easily implemented in risk assessments using commercial software packages.

Autism Research and Services for Young Children: History, Progress and Challenges

ERIC Educational Resources Information Center

Thompson, Travis

2013-01-01

For three decades after Leo Kanner's first clinical description, research progress in understanding and treating autism was minimal but since the late 1960s the growth of autism discoveries has been exponential, with a remarkable number of new findings published over the past two decades, in particular. These advances were made possible first by…

Malolactic bioconversion using a Oenococcus oeni strain for cider production: effect of yeast extract supplementation.

PubMed

Herrero, Mónica; García, Luis A; Díaz, Mario

2003-12-01

Yeast extract addition to reconstituted apple juice had a positive impact on the development of the malolactic starter culture used to ensure malolactic fermentation in cider, using active but non-proliferating cells. In this work, the reuse of fermentation lees from cider is proposed as an alternative to the use of commercial yeast extract products. Malolactic enzymatic assays, both in whole cells and cell-free extracts, were carried out to determine the best time to harvest cells for use as an inoculum in cider. Cells harvested at the late exponential phase, the physiological stage of growth corresponding to the maximum values of specific malolactic activity, achieved a good rate of malic acid degradation in controlled cider fermentation. Under the laboratory conditions used, malic acid degradation rates in the fermentation media turned out to be near 2.0 and 2.5 times lower, compared with the rates obtained in whole-cell enzymatic assays, as useful data applicable to industrial cider production.

Total lipid and fatty acid composition of eight strains of marine diatoms

NASA Astrophysics Data System (ADS)

Liang, Ying; Mai, Kang-Sen; Sun, Shi-Chun

2000-12-01

Fatty acid composition and total lipid content of 8 strains of marine diatoms ( Nitzschia frustrula, Nitzschia closterium, Nitzschia incerta, Navicula pelliculosa, Phaeodactylum tricornutum, Synedra fragilaroides) were examined. The microalgae were grown under defined conditions and harvested at the late exponential phase. The major fatty acids in most strains were 14∶0 (1.0% 6.3%), 16∶0 (13.5 26.4%), 16∶1n-7 (21.1% 46.3%) and 20∶5n-3 (6.5% 19.5%). The polyunsaturated fatty acids 16∶2n-4, 16∶3n-4, 16∶4n-1 and 20∶4n-6 also comprised a significant proportion of the total fatty acids in some strains. The characteristic fatty acid composition of diatoms is readily distinguishable from those of other microalgal groups. Significant concentration of the polyunsaturated fatty acid 20∶5n-3 (eicosapentaenoic acid) was present in each strain, with the highest proportion in B222 (19.5%).

Exponential evolution: implications for intelligent extraterrestrial life.

PubMed

Russell, D A

1983-01-01

Some measures of biologic complexity, including maximal levels of brain development, are exponential functions of time through intervals of 10(6) to 10(9) yrs. Biological interactions apparently stimulate evolution but physical conditions determine the time required to achieve a given level of complexity. Trends in brain evolution suggest that other organisms could attain human levels within approximately 10(7) yrs. The number (N) and longevity (L) terms in appropriate modifications of the Drake Equation, together with trends in the evolution of biological complexity on Earth, could provide rough estimates of the prevalence of life forms at specified levels of complexity within the Galaxy. If life occurs throughout the cosmos, exponential evolutionary processes imply that higher intelligence will soon (10(9) yrs) become more prevalent than it now is. Changes in the physical universe become less rapid as time increases from the Big Bang. Changes in biological complexity may be most rapid at such later times. This lends a unique and symmetrical importance to early and late universal times.

Modeling the Role of Dislocation Substructure During Class M and Exponential Creep. Revised

NASA Technical Reports Server (NTRS)

Raj, S. V.; Iskovitz, Ilana Seiden; Freed, A. D.

1995-01-01

The different substructures that form in the power-law and exponential creep regimes for single phase crystalline materials under various conditions of stress, temperature and strain are reviewed. The microstructure is correlated both qualitatively and quantitatively with power-law and exponential creep as well as with steady state and non-steady state deformation behavior. These observations suggest that creep is influenced by a complex interaction between several elements of the microstructure, such as dislocations, cells and subgrains. The stability of the creep substructure is examined in both of these creep regimes during stress and temperature change experiments. These observations are rationalized on the basis of a phenomenological model, where normal primary creep is interpreted as a series of constant structure exponential creep rate-stress relationships. The implications of this viewpoint on the magnitude of the stress exponent and steady state behavior are discussed. A theory is developed to predict the macroscopic creep behavior of a single phase material using quantitative microstructural data. In this technique the thermally activated deformation mechanisms proposed by dislocation physics are interlinked with a previously developed multiphase, three-dimensional. dislocation substructure creep model. This procedure leads to several coupled differential equations interrelating macroscopic creep plasticity with microstructural evolution.

Analysis and IbM simulation of the stages in bacterial lag phase: basis for an updated definition.

PubMed

Prats, Clara; Giró, Antoni; Ferrer, Jordi; López, Daniel; Vives-Rego, Josep

2008-05-07

The lag phase is the initial phase of a culture that precedes exponential growth and occurs when the conditions of the culture medium differ from the pre-inoculation conditions. It is usually defined by means of cell density because the number of individuals remains approximately constant or slowly increases, and it is quantified with the lag parameter lambda. The lag phase has been studied through mathematical modelling and by means of specific experiments. In recent years, Individual-based Modelling (IbM) has provided helpful insights into lag phase studies. In this paper, the definition of lag phase is thoroughly examined. Evolution of the total biomass and the total number of bacteria during lag phase is tackled separately. The lag phase lasts until the culture reaches a maximum growth rate both in biomass and cell density. Once in the exponential phase, both rates are constant over time and equal to each other. Both evolutions are split into an initial phase and a transition phase, according to their growth rates. A population-level mathematical model is presented to describe the transitional phase in cell density. INDividual DIScrete SIMulation (INDISIM) is used to check the outcomes of this analysis. Simulations allow the separate study of the evolution of cell density and total biomass in a batch culture, they provide a depiction of different observed cases in lag evolution at the individual-cell level, and are used to test the population-level model. The results show that the geometrical lag parameter lambda is not appropriate as a universal definition for the lag phase. Moreover, the lag phase cannot be characterized by a single parameter. For the studied cases, the lag phases of both the total biomass and the population are required to fully characterize the evolution of bacterial cultures. The results presented prove once more that the lag phase is a complex process that requires a more complete definition. This will be possible only after the phenomena governing the population dynamics at an individual level of description, and occurring during the lag and exponential growth phases, are well understood.

Disordered Kitaev chains with long-range pairing.

PubMed

Cai, Xiaoming

2017-03-22

We study the competition of disorder and superconductivity for a generalized Kitaev model in incommensurate potentials. The generalized Kitaev model describes one dimensional spinless fermions with long-range p-wave superconducting pairing, which decays with distance l as a power law  ∼[Formula: see text]. We focus on the transition from the topological superconducting phase to the topologically trivial Anderson localized phase, and effects of the exponent α on this phase transition. In the topological superconducting phase, for a system under open boundary condition the amplitude of zero-mode Majorana fermion has a hybrid exponential-algebraic decay as the distance increases from the edge. In the Anderson localized phase, some single-particle states remain critical for very strong disorders and the number of critical states increases as α decreases. In addition, except for critical disorders, the correlation function always has an exponential decay at the short range and an algebraic decay at the long range. Phase transition points are also numerically determined and the topological phase transition happens earlier at a smaller disorder strength for a system with smaller α.

Assessment of Enterotoxin Production and Cross-Contamination of Staphylococcus aureus between Food Processing Materials and Ready-To-Eat Cooked Fish Paste.

PubMed

Tango, Charles Nkufi; Hong, Sung-Sam; Wang, Jun; Oh, Deog-Hwan

2015-12-01

This study evaluated Staphylococcus aureus growth and subsequent staphylococcal enterotoxin A production in tryptone soy broth and on ready-to-eat cooked fish paste at 12 to 37 °C, as well as cross-contamination between stainless steel, polyethylene, and latex glove at room temperature. A model was developed using Barany and Roberts's growth model, which satisfactorily described the suitable growth of S. aureus with R(2)-adj from 0.94 to 0.99. Except at 12 °C, S. aureus cells in TSB presented a lag time lower (14.64 to 1.65 h), grew faster (0.08 to 0.31 log CFU/h) and produced SEA at lower cell density levels (5.65 to 6.44 log CFU/mL) compare to those inoculated on cooked fish paste with data of 16.920 to 1.985 h, 0.02 to 0.23 log CFU/h, and 6.19 to 7.11 log CFU/g, respectively. Staphylococcal enterotoxin type A (SEA) visual immunoassay test showed that primary SEA detection varied considerably among different storage temperature degrees and media. For example, it occurred only during exponential phase at 30 and 37 °C in TSB, but in cooked fish paste it took place at late exponential phase of S. aureus growth at 20 and 25 °C. The SEA detection test was negative on presence of S. aureus on cooked fish paste stored at 12 and 15 °C, although cell density reached level of 6.12 log CFU/g at 15 °C. Cross-contamination expressed as transfer rate of S. aureus from polyethylene surface to cooked fish paste surface was slower than that observed with steel surface to cooked fish paste under same conditions. These results provide helpful information for controlling S. aureus growth, SEA production and cross-contamination during processing of cooked fish paste. © 2015 Institute of Food Technologists®

Generalized optimal design for two-arm, randomized phase II clinical trials with endpoints from the exponential dispersion family.

PubMed

Jiang, Wei; Mahnken, Jonathan D; He, Jianghua; Mayo, Matthew S

2016-11-01

For two-arm randomized phase II clinical trials, previous literature proposed an optimal design that minimizes the total sample sizes subject to multiple constraints on the standard errors of the estimated event rates and their difference. The original design is limited to trials with dichotomous endpoints. This paper extends the original approach to be applicable to phase II clinical trials with endpoints from the exponential dispersion family distributions. The proposed optimal design minimizes the total sample sizes needed to provide estimates of population means of both arms and their difference with pre-specified precision. Its applications on data from specific distribution families are discussed under multiple design considerations. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

The Quiet Revolution that Transformed Women's Employment, Education, and Family. NBER Working Paper No. 11953

ERIC Educational Resources Information Center

Goldin, Claudia

2006-01-01

The modern economic role of women emerged in four phases. The first three were evolutionary; the last was revolutionary. Phase I occurred from the late nineteenth century to the 1920s; Phase II was from 1930 to 1950; Phase III extended from 1950 to the late 1970s; and Phase IV, the "quiet revolution," began in the late 1970s and is still ongoing.…

[Effect of the development phase and growth rate of a Shigella sonnei population on the reproduction of homologous bacteriophage].

PubMed

Voroshilova, N N; Kazakova, T B

1983-04-01

This study showed that the minimum latent period (20 minutes) of the intracellular multiplication of dysentery bacteriophage S-9 in the population of S. sonnei substrate strain under the conditions of static heterogeneous surface batch cultivation was observed at the end of the lag phase and at the growth acceleration phase, in the first and second thirds of the exponential curve, while the maximum latent period (35-40 minutes) was observed at the stationary phase. The maximum yield of phage S-9 from one infected bacterial cell (628.3 +/- 116.8) was registered during the first third of the phase of the exponential growth of the bacterial population and the minimum yield (18.66 +/- 6.6), at the beginning of the lag phase. The significant direct correlation between the specific growth rate of the bacterial population and the yield of the phage from one infected bacterial cell at the end of the lag phase, at the growth acceleration and deceleration phases, as well as the significant inverse correlation between the yield of the phage and the time of the generation of the bacterial population at the growth acceleration phase were established.

Efficient and stable exponential time differencing Runge-Kutta methods for phase field elastic bending energy models

NASA Astrophysics Data System (ADS)

Wang, Xiaoqiang; Ju, Lili; Du, Qiang

2016-07-01

The Willmore flow formulated by phase field dynamics based on the elastic bending energy model has been widely used to describe the shape transformation of biological lipid vesicles. In this paper, we develop and investigate some efficient and stable numerical methods for simulating the unconstrained phase field Willmore dynamics and the phase field Willmore dynamics with fixed volume and surface area constraints. The proposed methods can be high-order accurate and are completely explicit in nature, by combining exponential time differencing Runge-Kutta approximations for time integration with spectral discretizations for spatial operators on regular meshes. We also incorporate novel linear operator splitting techniques into the numerical schemes to improve the discrete energy stability. In order to avoid extra numerical instability brought by use of large penalty parameters in solving the constrained phase field Willmore dynamics problem, a modified augmented Lagrange multiplier approach is proposed and adopted. Various numerical experiments are performed to demonstrate accuracy and stability of the proposed methods.

How polyamine synthesis inhibitors and cinnamic acid affect tropane alkaloid production.

PubMed

Marconi, Patricia L; Alvarez, María A; Pitta-Alvarez, Sandra I

2007-01-01

Hairy roots of Brugmansia candida produce the tropane alkaloids scopolamine and hyoscyamine. In an attempt to divert the carbon flux from competing pathways and thus enhance productivity, the polyamine biosynthesis inhibitors cyclohexylamine (CHA) and methylglyoxal-bis-guanylhydrazone (MGBG) and the phenylalanine-ammonia-lyase inhibitor cinnamic acid were used. CHA decreased the specific productivity of both alkaloids but increased significantly the release of scopolamine (approx 500%) when it was added in the mid-exponential phase. However, when CHA was added for only 48 h during the exponential phase, the specific productivity of both alkaloids increased (approx 200%), favoring scopolamine. Treatment with MGBG was detrimental to growth but promoted release into the medium of both alkaloids. However, when it was added for 48 h during the exponential phase, MGBG increased the specific productivity (approx 200%) and release (250- 1800%) of both alkaloids. Cinnamic acid alone also favored release but not specific productivity. When a combination of CHA or MGBG with cinnamic acid was used, the results obtained were approximately the same as with each polyamine biosynthesis inhibitor alone, although to a lesser extent. Regarding root morphology, CHA inhibited growth of primary roots and ramification. However, it had a positive effect on elongation of lateral roots.

Stretched-to-compressed-exponential crossover observed in the electrical degradation kinetics of some spinel-metallic screen-printed structures

NASA Astrophysics Data System (ADS)

Balitska, V.; Shpotyuk, O.; Brunner, M.; Hadzaman, I.

2018-02-01

Thermally-induced (170 °C) degradation-relaxation kinetics is examined in screen-printed structures composed of spinel Cu0.1Ni0.1Co1.6Mn1.2O4 ceramics with conductive Ag or Ag-Pd layered electrodes. Structural inhomogeneities due to Ag and Ag-Pd diffusants in spinel phase environment play a decisive role in non-exponential kinetics of negative relative resistance drift. If Ag migration in spinel is inhibited by Pd addition due to Ag-Pd alloy, the kinetics attains stretched exponential behavior with ∼0.58 exponent, typical for one-stage diffusion in structurally-dispersive media. Under deep Ag penetration into spinel ceramics, as for thick films with Ag-layered electrodes, the degradation kinetics drastically changes, attaining features of two-step diffusing process governed by compressed-exponential dependence with power index of ∼1.68. Crossover from stretched- to compressed-exponential kinetics in spinel-metallic structures is mapped on free energy landscape of non-barrier multi-well system under strong perturbation from equilibrium, showing transition with a character downhill scenario resulting in faster than exponential decaying.

Production and Reutilization of Fluorescent Dissolved Organic Matter by a Marine Bacterial Strain, Alteromonas macleodii

PubMed Central

Goto, Shuji; Tada, Yuya; Suzuki, Koji; Yamashita, Youhei

2017-01-01

The recalcitrant fraction of marine dissolved organic matter (DOM) plays an important role in carbon storage on the earth’s surface. Bacterial production of recalcitrant DOM (RDOM) has been proposed as a carbon sequestration process. It is still unclear whether bacterial physiology can affect RDOM production. In this study, we conducted a batch culture using the marine bacterial isolate Alteromonas macleodii, a ubiquitous gammaproteobacterium, to evaluate the linkage between bacterial growth and DOM production. Glucose (1 mmol C L-1) was used as the sole carbon source, and the bacterial number, the DOM concentration in terms of carbon, and the excitation–emission matrices (EEMs) of DOM were monitored during the 168-h incubation. The incubation period was partitioned into the exponential growth (0–24 h) and stationary phases (24–168 h) based on the growth curve. Although the DOM concentration decreased during the exponential growth phase due to glucose consumption, it remained stable during the stationary phase, corresponding to approximately 4% of the initial glucose in terms of carbon. Distinct fluorophores were not evident in the EEMs at the beginning of the incubation, but DOM produced by the strain exhibited five fluorescent peaks during exponential growth. Two fluorescent peaks were similar to protein-like fluorophores, while the others could be categorized as humic-like fluorophores. All fluorophores increased during the exponential growth phase. The tryptophan-like fluorophore decreased during the stationary phase, suggesting that the strain reused the large exopolymer. The tyrosine-like fluorophore seemed to be stable during the stationary phase, implying that the production of tyrosine-containing small peptides through the degradation of exopolymers was correlated with the reutilization of the tyrosine-like fluorophore. Two humic-like fluorophores that showed emission maxima at the longer wavelength (525 nm) increased during the stationary phase, while the other humic-like fluorophore, which had a shorter emission wavelength (400 nm) and was categorized as recalcitrant, was stable. These humic-like fluorophore behaviors during incubation indicated that the composition of bacterial humic-like fluorophores, which were unavailable to the strain, differed between growth phases. Our results suggest that bacterial physiology can affect RDOM production and accumulation in the ocean interior. PMID:28400762

Influence of the Crc regulator on the hierarchical use of carbon sources from a complete medium in Pseudomonas.

PubMed

La Rosa, Ruggero; Behrends, Volker; Williams, Huw D; Bundy, Jacob G; Rojo, Fernando

2016-03-01

The Crc protein, together with the Hfq protein, participates in catabolite repression in pseudomonads, helping to coordinate metabolism. Little is known about how Crc affects the hierarchy of metabolite assimilation from complex mixtures. Using proton Nuclear Magnetic Resonance (NMR) spectroscopy, we carried out comprehensive metabolite profiling of culture supernatants (metabolic footprinting) over the course of growth of both Pseudomonas putida and P. aeruginosa, and compared the wild-type strains with deletion mutants for crc. A complex metabolite consumption hierarchy was observed, which was broadly similar between the two species, although with some important differences, for example in sugar utilization. The order of metabolite utilization changed upon inactivation of the crc gene, but even in the Crc-null strains some compounds were completely consumed before late metabolites were taken up. This suggests the presence of additional regulatory elements that determine the time and order of consumption of compounds. Unexpectedly, the loss of Crc led both species to excrete acetate and pyruvate as a result of unbalanced growth during exponential phase, compounds that were later consumed in stationary phase. This loss of carbon during growth helps to explain the contribution of the Crc/Hfq regulatory system to evolutionary fitness of pseudomonads. © 2015 Society for Applied Microbiology and John Wiley & Sons Ltd.

Incorporation of [14C]shikimate into phenazines and their further metabolism by Pseudomonas phenazinium

PubMed Central

Byng, Graham S.; Turner, John M.

1977-01-01

1. During growth of Pseudomonas phenazinium on l-threonine medium, phenazine pigment formation commenced early and 1,6-dihydroxyphenazine 5,10-dioxide (iodinin) was the major component. Growth on l-[U-14C]threonine showed that when growth was complete about 25% of the label had been incorporated into phenazines and 30% into cell substance. 2. The addition of d-[2,3,4,5(n)-14C]shikimate to cultures at different phases of growth showed that the greatest efficiency of incorporation (about 70%) occurred in the mid- to late-exponential phase. Phenazines accounting for most of the 14C supplied were iodinin and 9-hydroxyphenazine-1-carboxylate plus 2,9-dihydroxyphenazine-1-carboxylate. Radioactivity incorporated into cell substance was about one-third of the amount found in phenazines. 3. Kinetic studies showed that radioactivity from a pulse of [14C]-shikimate was incorporated into phenazines immediately, without a discernible lag, and into all detectable phenazines simultaneously rather than sequentially. 4. Radioactive phenazines isolated from culture media were fed to growing cultures and their metabolism was studied. The results supported a scheme for the biosynthesis of iodinin and 1,8-dihydroxyphenazine 10-monoxide by a branched pathway. 5. It is proposed that phenazine-1,6-dicarboxylate is the common precursor of all naturally occurring phenazines. PMID:880226

Ingestion of Brachionus plicatilis under different microalgae conditions

NASA Astrophysics Data System (ADS)

Zhou, Wenli; Tang, Xuexi; Qiao, Xiuting; Wang, You; Wang, Renjun; Feng, Lei

2009-09-01

The effects of four microalgae, Chlorella vulgaris, Platymonas helgolandicavar, Isochrysis galbana, and Nitzschia closterium on the grazing and filtering rates of the marine rotifer, Brachionus plicatilis, were evaluated under laboratory conditions. The grazing rates in separate cultures of the four microalga were as follows: C. vulgaris > P. helgolandicavar > I. galbana > N. closterium. However, the filtering rates occurred in the following order: P. helgolandicavar > N. closterium > C. vulgaris > I. galbana. A mixed diets experiment revealed that P. helgolandicavar was the preferred diet of B. plicatilis. In addition, the grazing rate of B. plicatilis increased gradually as the density of the microalgae increased, until concentrations of 2.5×106 cells mL-1 for C. vulgaris and 1.5×106 cells mL-1 for I. galbana were obtained. Furthermore, the filtering rate increased slightly when the density of the microalgae was low, after which it declined as the microalgal density increased. The grazing rates of B. plicatilis were as follows during the different growth phases: stationary phase > exponential phase > lag phase > decline phase. Additionally, the filtering rates during the growth phases were: exponential phase > lag phase > stationary phase > decline phase. The results of this study provide foundational information that can be used to explore the optimal culture conditions for rotifers and to promote the development of aquaculture.

Growth phase-dependent induction of stationary-phase promoters of Escherichia coli in different gram-negative bacteria.

PubMed Central

Miksch, G; Dobrowolski, P

1995-01-01

RSF1010-derived plasmids carrying a fusion of a promoterless lacZ gene with the sigma s-dependent growth phase-regulated promoters of Escherichia coli, bolAp1 and fic, were constructed. The plasmids were mobilized into the gram-negative bacterial species Acetobacter methanolicus, Xanthomonas campestris, Pseudomonas putida, and Rhizobium meliloti. The beta-galactosidase activities of bacterial cultures were determined during exponential and stationary growth phases. Transcriptional activation of the fic promoter in the different bacteria was growth phase dependent as in E. coli and was initiated generally during the transition to stationary phase. The induction of the bolA promoter was also growth phase dependent in the bacteria tested. While the expression in E. coli and R. meliloti was initiated during the transition from exponential to stationary phase, the induction in A. methanolicus, P. putida, and X. campestris started some hours after stationary growth phase was reached. In all the species tested, DNA fragments hybridizing with the rpoS gene of E. coli were detected. The results show that in different gram-negative bacteria, stationary-phase-specific sigma factors which are structurally and functionally homologous to sigma s and are able to recognize the promoter sequences of both bolA and fic exist. PMID:7665531

Characterization of pH dependent Mn(II) oxidation strategies and formation of a bixbyite-like phase by Mesorhizobium australicum T-G1

PubMed Central

Bohu, Tsing; Santelli, Cara M.; Akob, Denise M.; Neu, Thomas R.; Ciobota, Valerian; Rösch, Petra; Popp, Jürgen; Nietzsche, Sándor; Küsel, Kirsten

2015-01-01

Despite the ubiquity of Mn oxides in natural environments, there are only a few observations of biological Mn(II) oxidation at pH < 6. The lack of low pH Mn-oxidizing bacteria (MOB) isolates limits our understanding of how pH influences biological Mn(II) oxidation in extreme environments. Here, we report that a novel MOB isolate, Mesorhizobium australicum strain T-G1, isolated from an acidic and metalliferous uranium mining area, can oxidize Mn(II) at both acidic and neutral pH using different enzymatic pathways. X-ray diffraction, Raman spectroscopy, and scanning electron microscopy with energy dispersive X-ray spectroscopy revealed that T-G1 initiated bixbyite-like Mn oxide formation at pH 5.5 which coincided with multi-copper oxidase expression from early exponential phase to late stationary phase. In contrast, reactive oxygen species (ROS), particularly superoxide, appeared to be more important for T-G1 mediated Mn(II) oxidation at neutral pH. ROS was produced in parallel with the occurrence of Mn(II) oxidation at pH 7.2 from early stationary phase. Solid phase Mn oxides did not precipitate, which is consistent with the presence of a high amount of H2O2 and lower activity of catalase in the liquid culture at pH 7.2. Our results show that M. australicum T-G1, an acid tolerant MOB, can initiate Mn(II) oxidation by varying its oxidation mechanisms depending on the pH and may play an important role in low pH manganese biogeochemical cycling. PMID:26236307

Proteome analysis to assess physiological changes in Escherichia coli grown under glucose-limited fed-batch conditions.

PubMed

Raman, Babu; Nandakumar, M P; Muthuvijayan, Vignesh; Marten, Mark R

2005-11-05

Proteome analysis was used to compare global protein expression changes in Escherichia coli fermentation between exponential and glucose-limited fed-batch phase. Two-dimensional gel electrophoresis and MALDI-TOF mass spectrometry were used to separate and identify 49 proteins showing >2-fold difference in expression. Proteins upregulated during exponential phase include ribonucleotide biosynthesis enzymes and ribosomal recycling factor. Proteins upregulated during fed-batch phase include those involved in high-affinity glucose uptake, transport and degradation of alternate carbon sources and TCA cycle, suggesting an enhanced role of the cycle under glucose- and energy-limited conditions. We report the upregulation of several putative proteins (ytfQ, ygiS, ynaF, yggX, yfeX), not identified in any previous study under carbon-limited conditions. Copyright (c) 2005 Wiley Periodicals, Inc.

Supersymmetrical bounding of asymmetric states and quantum phase transitions by anti-crossing of symmetric states

PubMed Central

Afzal, Muhammad Imran; Lee, Yong Tak

2016-01-01

Von Neumann and Wigner theorized the bounding and anti-crossing of eigenstates. Experiments have demonstrated that owing to anti-crossing and similar radiation rates, the graphene-like resonance of inhomogeneously strained photonic eigenstates can generate a pseudomagnetic field, bandgaps and Landau levels, whereas exponential or dissimilar rates induce non-Hermicity. Here, we experimentally demonstrate higher-order supersymmetry and quantum phase transitions by resonance between similar one-dimensional lattices. The lattices consisted of inhomogeneous strain-like phases of triangular solitons. The resonance created two-dimensional, inhomogeneously deformed photonic graphene. All parent eigenstates were annihilated. Eigenstates of mildly strained solitons were annihilated at similar rates through one tail and generated Hermitian bounded eigenstates. The strongly strained solitons with positive phase defects were annihilated at exponential rates through one tail, which bounded eigenstates through non-Hermitianally generated exceptional points. Supersymmetry was evident, with preservation of the shapes and relative phase differences of the parent solitons. Localizations of energies generated from annihilations of mildly and strongly strained soliton eigenstates were responsible for geometrical (Berry) and topological phase transitions, respectively. Both contributed to generating a quantum Zeno phase, whereas only strong twists generated topological (Anderson) localization. Anti-bunching-like condensation was also observed. PMID:27966596

Utilisation of Carbon Sources by Pythium, Phytophthora and Fusarium Species as Determined by Biolog® Microplate Assay

PubMed Central

Khalil, Sammar; Alsanius, Beatrix W

2009-01-01

This study examined the metabolic activity of pure cultures of five root pathogens commonly found in closed hydroponic cultivation systems (Phytophthora cryptogea (PC), Phytophthora capsici (PCP), Pythium aphanidermatum (PA), Fusarium oxysporum f.sp. radicis-lycopersici (FORL) and Fusarium solani (FS)) using sole carbon source utilisation in order to develop effective biocontrol strategies against these pathogens. Aliquots of 150 µL of the mycelial suspension were inoculated in each well of GN2 microtitre plates. On the basis of average well colour development and number of positive wells, the pathogens were divided into two groups, (i) PA and FORL and (ii) PC, PCP and FS. Group (i) was characterised by a short lag-phase, a rapid exponential phase involving almost all carbon sources offered and a long stationary phase, while group (ii) had a more extended lag-phase and a slower utilisation rate of the carbon sources offered. The three isolates in group (ii) differed significantly during their exponential phase. The lowest utilisation rate of carbon sources and number of sources utilised was found for PCP. Of the major group of carbon sources, six carbohydrates, three carboxylic acids and four amino acids were rapidly used by all isolates tested at an early stage. The carbon sources gentibiose, α-D-glucose, maltose, sucrose, D-trehalose, L-aspartic acid, L-glutamic acid, L-proline persisted to the end of the exponential phase.Moreover, similarities between the metabolic profiles of the tested pathogen and the those of the resident microflora could also be found. These findings are of great importance as regards the role of the resident microflora in the biocontrol. PMID:19294012

C-Peptide Decline in Type 1 Diabetes Has Two Phases: An Initial Exponential Fall and a Subsequent Stable Phase.

PubMed

Shields, Beverley M; McDonald, Timothy J; Oram, Richard; Hill, Anita; Hudson, Michelle; Leete, Pia; Pearson, Ewan R; Richardson, Sarah J; Morgan, Noel G; Hattersley, Andrew T

2018-06-07

The decline in C-peptide in the 5 years after diagnosis of type 1 diabetes has been well studied, but little is known about the longer-term trajectory. We aimed to examine the association between log-transformed C-peptide levels and the duration of diabetes up to 40 years after diagnosis. We assessed the pattern of association between urinary C-peptide/creatinine ratio (UCPCR) and duration of diabetes in cross-sectional data from 1,549 individuals with type 1 diabetes using nonlinear regression approaches. Findings were replicated in longitudinal follow-up data for both UCPCR ( n = 161 individuals, 326 observations) and plasma C-peptide ( n = 93 individuals, 473 observations). We identified two clear phases of C-peptide decline: an initial exponential fall over 7 years (47% decrease/year [95% CI -51%, -43%]) followed by a stable period thereafter (+0.07%/year [-1.3, +1.5]). The two phases had similar durations and slopes in patients above and below the median age at diagnosis (10.8 years), although levels were lower in the younger patients irrespective of duration. Patterns were consistent in both longitudinal UCPCR ( n = 162; ≤7 years duration: -48%/year [-55%, -38%]; >7 years duration -0.1% [-4.1%, +3.9%]) and plasma C-peptide ( n = 93; >7 years duration only: -2.6% [-6.7%, +1.5%]). These data support two clear phases of C-peptide decline: an initial exponential fall over a 7-year period, followed by a prolonged stabilization where C-peptide levels no longer decline. Understanding the pathophysiological and immunological differences between these two phases will give crucial insights into understanding β-cell survival. © 2018 by the American Diabetes Association.

Colloquium: Statistical mechanics of money, wealth, and income

NASA Astrophysics Data System (ADS)

Yakovenko, Victor M.; Rosser, J. Barkley, Jr.

2009-10-01

This Colloquium reviews statistical models for money, wealth, and income distributions developed in the econophysics literature since the late 1990s. By analogy with the Boltzmann-Gibbs distribution of energy in physics, it is shown that the probability distribution of money is exponential for certain classes of models with interacting economic agents. Alternative scenarios are also reviewed. Data analysis of the empirical distributions of wealth and income reveals a two-class distribution. The majority of the population belongs to the lower class, characterized by the exponential (“thermal”) distribution, whereas a small fraction of the population in the upper class is characterized by the power-law (“superthermal”) distribution. The lower part is very stable, stationary in time, whereas the upper part is highly dynamical and out of equilibrium.

Multi-time series RNA-seq analysis of Enterobacter lignolyticus SCF1 during growth in lignin-amended medium

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

Orellana, Roberto; Chaput, Gina; Markillie, Lye Meng

The production of lignocellulosic-derived biofuels is a highly promising source of alternative energy, but it has been constrained by the lack of a microbial platform capable to efficiently degrade this recalcitrant material and cope with by-products that can be toxic to cells. Species that naturally grow in environments where carbon is mainly available as lignin are promising for finding new ways of removing the lignin that protects cellulose for improved conversion of lignin to fuel precursors. Enterobacter lignolyticus SCF1 is a facultative anaerobic Gammaproteobacteria isolated from tropical rain forest soil collected in El Yunque forest, Puerto Rico under anoxic growthmore » conditions with lignin as sole carbon source. Whole transcriptome analysis of SCF1 during E.lignolyticus SCF1 lignin degradation was conducted on cells grown in the presence (0.1%, w/w) and the absence of lignin, where samples were taken at three different times during growth, beginning of exponential phase, midexponential phase and beginning of stationary phase. Lignin-amended cultures achieved twice the cell biomass as unamended cultures over three days, and in this time degraded 60% of lignin. Transcripts in early exponential phase reflected this accelerated growth. A complement of laccases, aryl-alcohol dehydrogenases, and peroxidases were most up-regulated in lignin amended conditions in mid-exponential and early stationary phases compared to unamended growth. The association of hydrogen production by way of the formate hydrogenlyase complex with lignin degradation suggests a possible value added to lignin degradation in the future.« less

Metabolism of azo dyes by human skin microbiota

PubMed Central

Stingley, Robin L.; Zou, Wen; Heinze, Thomas M.; Chen, Huizhong; Cerniglia, Carl E.

2018-01-01

Reduction of Methyl Red (MR) and Orange II (Or II) by 26 human skin bacterial species was monitored by a rapid spectrophotometric assay. The analysis indicated that skin bacteria, representing the genera Staphylococcus, Corynebacterium, Micrococcus, Dermacoccus and Kocuria, were able to reduce MR by 74–100 % in 24 h, with only three species unable to reduce completely the dye in that time. Among the species tested, only Corynebacterium xerosis was unable to reduce Or II to any degree by 24 h, and only Staphylococcus delphini, Staphylococcus sciuri subsp. sciuri and Pseudomonas aeruginosa were able to reduce completely this dye within 24 h. MR reduction started with early-exponential growth in Staphylococcus aureus and Staphylococcus epidermidis, and around late-exponential/early-stationary growth in P. aeruginosa. Reduction of Or II, Ponceau S and Ponceau BS started during late-exponential/early-stationary growth for all three species. Using liquid chromatography/electrospray ionization mass spectrometry analyses, MR metabolites produced by Staph. aureus, Staph. epidermidis and P. aeruginosa were identified as N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Searches of available genomic and proteomic data revealed that at least four of the staphylococci in this study, Staphylococcus haemolyticus, Staph. epidermidis, Staphylococcus cohnii and Staphylococcus saprophyticus, have hypothetical genes with 77, 76, 75 and 74 % sequence identity to azo1 encoding an azoreductase from Staph. aureus and hypothetical proteins with 82, 80, 72 and 74 % identity to Azo1, respectively. In addition, Staphylococcus capitis has a protein with 79 % identity to Azo1. Western analysis detected proteins similar to Azo1 in all the staphylococci tested, except Staph. delphini, Staph. sciuri subsp. sciuri and Staphylococcus auricularis. The data presented in this report will be useful in the risk assessment process for evaluation of public exposure to products containing these dyes. PMID:19729456

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

NASA Astrophysics Data System (ADS)

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny; Birkholzer, Jens T.

2017-11-01

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1-D, 2-D, and 3-D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, td. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, td0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the first two terms for high-accuracy approximations (with less than 10-7 relative error) for 1-D isotropic (spheres, cylinders, slabs) and 2-D/3-D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1-D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2-D/3-D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

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

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1D, 2D, and 3D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, t d0. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, t d0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the firstmore » two terms for high-accuracy approximations (with less than 10-7 relative error) for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2D/3D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.« less

Revisiting the Fundamental Analytical Solutions of Heat and Mass Transfer: The Kernel of Multirate and Multidimensional Diffusion

DOE PAGES

Zhou, Quanlin; Oldenburg, Curtis M.; Rutqvist, Jonny; ...

2017-10-24

There are two types of analytical solutions of temperature/concentration in and heat/mass transfer through boundaries of regularly shaped 1D, 2D, and 3D blocks. These infinite-series solutions with either error functions or exponentials exhibit highly irregular but complementary convergence at different dimensionless times, t d0. In this paper, approximate solutions were developed by combining the error-function-series solutions for early times and the exponential-series solutions for late times and by using time partitioning at the switchover time, t d0. The combined solutions contain either the leading term of both series for normal-accuracy approximations (with less than 0.003 relative error) or the firstmore » two terms for high-accuracy approximations (with less than 10-7 relative error) for 1D isotropic (spheres, cylinders, slabs) and 2D/3D rectangular blocks (squares, cubes, rectangles, and rectangular parallelepipeds). This rapid and uniform convergence for rectangular blocks was achieved by employing the same time partitioning with individual dimensionless times for different directions and the product of their combined 1D slab solutions. The switchover dimensionless time was determined to minimize the maximum approximation errors. Furthermore, the analytical solutions of first-order heat/mass flux for 2D/3D rectangular blocks were derived for normal-accuracy approximations. These flux equations contain the early-time solution with a three-term polynomial in √td and the late-time solution with the limited-term exponentials for rectangular blocks. The heat/mass flux equations and the combined temperature/concentration solutions form the ultimate kernel for fast simulations of multirate and multidimensional heat/mass transfer in porous/fractured media with millions of low-permeability blocks of varying shapes and sizes.« less

Metabolism of azo dyes by human skin microbiota.

PubMed

Stingley, Robin L; Zou, Wen; Heinze, Thomas M; Chen, Huizhong; Cerniglia, Carl E

2010-01-01

Reduction of Methyl Red (MR) and Orange II (Or II) by 26 human skin bacterial species was monitored by a rapid spectrophotometric assay. The analysis indicated that skin bacteria, representing the genera Staphylococcus, Corynebacterium, Micrococcus, Dermacoccus and Kocuria, were able to reduce MR by 74-100 % in 24 h, with only three species unable to reduce completely the dye in that time. Among the species tested, only Corynebacterium xerosis was unable to reduce Or II to any degree by 24 h, and only Staphylococcus delphini, Staphylococcus sciuri subsp. sciuri and Pseudomonas aeruginosa were able to reduce completely this dye within 24 h. MR reduction started with early-exponential growth in Staphylococcus aureus and Staphylococcus epidermidis, and around late-exponential/early-stationary growth in P. aeruginosa. Reduction of Or II, Ponceau S and Ponceau BS started during late-exponential/early-stationary growth for all three species. Using liquid chromatography/electrospray ionization mass spectrometry analyses, MR metabolites produced by Staph. aureus, Staph. epidermidis and P. aeruginosa were identified as N,N-dimethyl-p-phenylenediamine and 2-aminobenzoic acid. Searches of available genomic and proteomic data revealed that at least four of the staphylococci in this study, Staphylococcus haemolyticus, Staph. epidermidis, Staphylococcus cohnii and Staphylococcus saprophyticus, have hypothetical genes with 77, 76, 75 and 74 % sequence identity to azo1 encoding an azoreductase from Staph. aureus and hypothetical proteins with 82, 80, 72 and 74 % identity to Azo1, respectively. In addition, Staphylococcus capitis has a protein with 79 % identity to Azo1. Western analysis detected proteins similar to Azo1 in all the staphylococci tested, except Staph. delphini, Staph. sciuri subsp. sciuri and Staphylococcus auricularis. The data presented in this report will be useful in the risk assessment process for evaluation of public exposure to products containing these dyes.

Channel response to sediment release: insights from a paired analysis of dam removal

USGS Publications Warehouse

Collins, Mathias J.; Snyder, Noah P.; Boardman, Graham; Banks, William S.; Andrews, Mary; Baker, Matthew E.; Conlon, Maricate; Gellis, Allen; McClain, Serena; Miller, Andrew; Wilcock, Peter

2017-01-01

Dam removals with unmanaged sediment releases are good opportunities to learn about channel response to abruptly increased bed material supply. Understanding these events is important because they affect aquatic habitats and human uses of floodplains. A longstanding paradigm in geomorphology holds that response rates to landscape disturbance exponentially decay through time. However, a previous study of the Merrimack Village Dam (MVD) removal on the Souhegan River in New Hampshire, USA, showed that an exponential function poorly described the early geomorphic response. Erosion of impounded sediments there was two-phased. We had an opportunity to quantitatively test the two-phase response model proposed for MVD by extending the record there and comparing it with data from the Simkins Dam removal on the Patapsco River in Maryland, USA. The watershed sizes are the same order of magnitude (102 km2), and at both sites low-head dams were removed (~3–4 m) and ~65 000 m3 of sand-sized sediments were discharged to low-gradient reaches. Analyzing four years of repeat morphometry and sediment surveys at the Simkins site, as well as continuous discharge and turbidity data, we observed the two-phase erosion response described for MVD. In the early phase, approximately 50% of the impounded sediment at Simkins was eroded rapidly during modest flows. After incision to base level and widening, a second phase began when further erosion depended on floods large enough to go over bank and access impounded sediments more distant from the newly-formed channel. Fitting functional forms to the data for both sites, we found that two-phase exponential models with changing decay constants fit the erosion data better than single-phase models. Valley width influences the two-phase erosion responses upstream, but downstream responses appear more closely related to local gradient, sediment re-supply from the upstream impoundments, and base flows.

Antisense transcriptional interference mediates condition-specific gene repression in budding yeast.

PubMed

Nevers, Alicia; Doyen, Antonia; Malabat, Christophe; Néron, Bertrand; Kergrohen, Thomas; Jacquier, Alain; Badis, Gwenael

2018-05-18

Pervasive transcription generates many unstable non-coding transcripts in budding yeast. The transcription of such noncoding RNAs, in particular antisense RNAs (asRNAs), has been shown in a few examples to repress the expression of the associated mRNAs. Yet, such mechanism is not known to commonly contribute to the regulation of a given class of genes. Using a mutant context that stabilized pervasive transcripts, we observed that the least expressed mRNAs during the exponential phase were associated with high levels of asRNAs. These asRNAs also overlapped their corresponding gene promoters with a much higher frequency than average. Interrupting antisense transcription of a subset of genes corresponding to quiescence-enriched mRNAs restored their expression. The underlying mechanism acts in cis and involves several chromatin modifiers. Our results convey that transcription interference represses up to 30% of the 590 least expressed genes, which includes 163 genes with quiescence-enriched mRNAs. We also found that pervasive transcripts constitute a higher fraction of the transcriptome in quiescence relative to the exponential phase, consistent with gene expression itself playing an important role to suppress pervasive transcription. Accordingly, the HIS1 asRNA, normally only present in quiescence, is expressed in exponential phase upon HIS1 mRNA transcription interruption.

Survival and growth of Cochlodinium polykrikoides red tide after addition of yellow loess.

PubMed

Lee, Young Sik; Kim, Jung Dong; Lim, Weol Ae; Lee, Sam Geun

2009-11-01

We examined the survival rate of Cochlodinium polykrikoides after yellow loess addition and conducted culture experiments to investigate the possibility that red tides maybe caused by C. polykrikoides individuals that are precipitated when loess is added. At least 15% of the C. polykrikoides cells that precipitated to the bottom layer either by the addition of loess or no addition survived for 1 week at all growth phases, rather than disappearing immediately after precipitating. However no live cells were observed after 20 days, regardless of phase or loess addition. In the exponential phase, the number of C. polykrikoides cells increased to >2886 cells ml(-1) after loess was added. However in the stationary phase, the number of cells did not increase until 18 days. In the exponential phase, those C. polykrikoides that survived precipitation caused by scattering loess on cultures did not appear to have the ability to cause red tides again because of the short red tide periods in the field, long lag time after loess addition, and low survival rate after loess addition.

Early-Phase 11C-PiB PET in Amyloid Angiopathy-Related Symptomatic Cerebral Hemorrhage: Potential Diagnostic Value?

PubMed Central

Aigbirhio, Franklin I.; Fryer, Tim D.; Menon, David K.; Warburton, Elizabeth A.; Baron, Jean-Claude

2015-01-01

Although late-phase (>35min post-administration) 11C-PiB-PET has good sensitivity in cerebral amyloid angiopathy (CAA), its specificity is poor due to frequently high uptake in healthy aged subjects. By detecting perfusion-like abnormalities, early-phase 11C-PiB-PET might add diagnostic value. Early-frame (1–6min) 11C-PiB-PET was obtained in 11 non-demented patients with probable CAA-related symptomatic lobar intracerebral haemorrhage (70±7yrs), 9 age-matched healthy controls (HCs) and 10 HCs <55yrs. There was a significant decrease in early-phase atrophy-corrected whole-cortex SUV relative to cerebellar vermis (SUVR) in the CAA vs age-matched HC group. None of the age-matched controls fell below the lower 95% confidence limit derived from the young HCs, while 6/11 CAA patients did (sensitivity = 55%, specificity = 100%). Combining both early- and late-phase 11C-PiB data did not change the sensitivity and specificity of late-phase PiB, but combined early- and late-phase positivity entails a very high suspicion of underlying Aβ-related clinical disorder, i.e., CAA or Alzheimer disease (AD). In order to clarify this ambiguity, we then show that the occipital/posterior cingulate ratio is markedly lower in CAA than in AD (N = 7). These pilot data suggest that early-phase 11C-PiB-PET may not only add to late-phase PiB-PET with respect to the unclear situation of late-phase positivity, but also help differentiate CAA from AD. PMID:26439113

Exponential Acceleration of VT Seismicity in the Years Prior to Major Eruptions of Basaltic Volcanoes

NASA Astrophysics Data System (ADS)

Lengline, O.; Marsan, D.; Got, J.; Pinel, V.

2007-12-01

The evolution of the seismicity at three basaltic volcanoes (Kilauea, Mauna-Loa and Piton de la Fournaise) is analysed during phases of magma accumulation. We show that the VT seismicity during these time-periods is characterized by an exponential increase at long-time scale (years). Such an exponential acceleration can be explained by a model of seismicity forced by the replenishment of a magmatic reservoir. The increase in stress in the edifice caused by this replenishment is modeled. This stress history leads to a cumulative number of damage, ie VT earthquakes, following the same exponential increase as found for seismicity. A long-term seismicity precursor is thus detected at basaltic volcanoes. Although this precursory signal is not able to predict the onset times of futures eruptions (as no diverging point is present in the model), it may help mitigating volcanic hazards.

Differential utilization and transformation of sulfur allotropes, μ-S and α-S8, by moderate thermoacidophile Sulfobacillus thermosulfidooxidans.

PubMed

Nie, Zhen-yuan; Liu, Hong-chang; Xia, Jin-lan; Zhu, Hong-rui; Ma, Chen-yan; Zheng, Lei; Zhao, Yi-dong; Qiu, Guan-zhou

2014-10-01

The utilization of amorphous μ-S and orthorhombic α-S8 by thermoacidophile Sulfobacillus thermosulfidooxidans was firstly investigated in terms of cell growth and sulfur oxidation behavior. The morphology and surface sulfur speciation transformation were evaluated by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), Raman spectroscopy and sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy. The results showed that the strain grown on μ-S entered slower (about 1 day later) into the exponential phase, while grew faster in exponential phase and attained higher maximal cell density and lower pH than on α-S8. After bio-corrosion, both sulfur samples were evidently eroded, but only μ-S surface presented much porosity, while α-S8 maintained glabrous. μ-S began to be gradually converted into α-S8 from day 2 when the bacterial cells entered the exponential phase, with a final composition of 62.3% μ-S and 37.7% α-S8 on day 4 at the stationary phase. α-S8 was not found to transform into other species in the experiments with or without bacteria. These data indicated S. thermosulfidooxidans oxidized amorphous μ-S faster than orthorhombic α-S8, but the chain-like μ-S was transformed into cyclic α-S8 by S. thermosulfidooxidans. Copyright © 2014 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

Composition and occurrence of lipid droplets in the cyanobacterium Nostoc punctiforme.

PubMed

Peramuna, Anantha; Summers, Michael L

2014-12-01

Inclusions of neutral lipids termed lipid droplets (LDs) located throughout the cell were identified in the cyanobacterium Nostoc punctiforme by staining with lipophylic fluorescent dyes. LDs increased in number upon entry into stationary phase and addition of exogenous fructose indicating a role for carbon storage, whereas high-light stress did not increase LD numbers. LD accumulation increased when nitrate was used as the nitrogen source during exponential growth as compared to added ammonia or nitrogen-fixing conditions. Analysis of isolated LDs revealed enrichment of triacylglycerol (TAG), α-tocopherol, and C17 alkanes. LD TAG from exponential phase growth contained mainly saturated C16 and C18 fatty acids, whereas stationary phase LD TAG had additional unsaturated fatty acids characteristic of whole cells. This is the first characterization of cyanobacterial LD composition and conditions leading to their production. Based upon their abnormally large size and atypical location, these structures represent a novel sub-organelle in cyanobacteria.

Isolation of a variant of Candida albicans.

PubMed Central

Buckley, H R; Price, M R; Daneo-Moore, L

1982-01-01

During the course of Candida albicans antigen production, a variant of this organism was encountered which did not produce hyphae at 37 degrees C. Presented here are some of the characteristics of this variant. It produces hyphae at 25 degrees C on cornmeal agar and synthetic medium plus N-acetylglucosamine and Tween 80. At 37 degrees C, it does not produce hyphae on these media, although C. albicans normally does produce hyphae under these circumstances. In liquid synthetic medium, this variant does not produce hyphae at 37 degrees C. The variant strain was analyzed for DNA, RNA, protein content, and particle size. After 50 to 70 h in balanced exponential-phase growth, particle size distribution was narrow, and there were no differences in the DNA, RNA, or protein content per particle in the two strains. When balanced exponential-phase cultures were brought into stationary phase, both strains contained the same amount of DNA per cell. Images PMID:6752021

Isolation of a variant of Candida albicans.

PubMed

Buckley, H R; Price, M R; Daneo-Moore, L

1982-09-01

During the course of Candida albicans antigen production, a variant of this organism was encountered which did not produce hyphae at 37 degrees C. Presented here are some of the characteristics of this variant. It produces hyphae at 25 degrees C on cornmeal agar and synthetic medium plus N-acetylglucosamine and Tween 80. At 37 degrees C, it does not produce hyphae on these media, although C. albicans normally does produce hyphae under these circumstances. In liquid synthetic medium, this variant does not produce hyphae at 37 degrees C. The variant strain was analyzed for DNA, RNA, protein content, and particle size. After 50 to 70 h in balanced exponential-phase growth, particle size distribution was narrow, and there were no differences in the DNA, RNA, or protein content per particle in the two strains. When balanced exponential-phase cultures were brought into stationary phase, both strains contained the same amount of DNA per cell.

Biphasic and synergistic activation of p44mapk (ERK1) by growth factors: correlation between late phase activation and mitogenicity.

PubMed

Meloche, S; Seuwen, K; Pagès, G; Pouysségur, J

1992-05-01

We have examined the phosphorylation and protein kinase activity of p44 mitogen-activated protein kinase (p44mapk) in growth factor-stimulated hamster fibroblasts using a specific antiserum. The activity of p44mapk was stimulated both by receptor tyrosine kinases and G protein-coupled receptors. Detailed kinetics revealed that alpha-thrombin induces a biphasic activation of p44mapk in CCL39 cells: a rapid phase appearing at 5-10 min was followed by a late and sustained phase still elevated after 4 h. Inactivation of alpha-thrombin with hirudin after 30 sec, which prevented DNA synthesis, did not alter the early p44mapk response but completely abolished the late phase. Pretreatment of the cells with pertussis toxin, which inhibits by more than 95% alpha-thrombin-induced mitogenicity, resulted in the complete loss of late phase activity, while the early peak was partially attenuated. Treatment of CCL39 cells with basic fibroblast growth factor also induced a strong activation of p44mapk. Serotonin, which is not a mitogen by its own, had no effect on late phase p44mapk activity, but synergized with basic fibroblast growth factor to induce late kinase response and DNA synthesis. Both early and late phase activation of p44mapk were accompanied by tyrosine phosphorylation of the enzyme. Together, the results indicate that there is a very close correlation between the ability of a growth factor to induce late and sustained p44mapk activation and its mitogenic potential. Therefore, we propose that sustained p44mapk activation is an obligatory event for growth factor-induced cell cycle progression.

Growth phase-dependent proteomes of the Malaysian isolated Lactococcus lactis dairy strain M4 using label-free qualitative shotgun proteomics analysis.

PubMed

Yap, Theresa Wan Chen; Rabu, Amir; Abu Bakar, Farah Diba; Rahim, Raha Abdul; Mahadi, Nor Muhammad; Illias, Rosli Md; Murad, Abdul Munir Abdul

2014-01-01

Lactococcus lactis is the most studied mesophilic fermentative lactic acid bacterium. It is used extensively in the food industry and plays a pivotal role as a cell factory and also as vaccine delivery platforms. The proteome of the Malaysian isolated L. lactis M4 dairy strain, obtained from the milk of locally bred cows, was studied to elucidate the physiological changes occurring between the growth phases of this bacterium. In this study, ultraperformance liquid chromatography nanoflow electrospray ionization tandem mass spectrometry (UPLC- nano-ESI-MS(E)) approach was used for qualitative proteomic analysis. A total of 100 and 121 proteins were identified from the midexponential and early stationary growth phases, respectively, of the L. lactis strain M4. During the exponential phase, the most important reaction was the generation of sufficient energy, whereas, in the early stationary phase, the metabolic energy pathways decreased and the biosynthesis of proteins became more important. Thus, the metabolism of the cells shifted from energy production in the exponential phase to the synthesis of macromolecules in the stationary phase. The resultant proteomes are essential in providing an improved view of the cellular machinery of L. lactis during the transition of growth phases and hence provide insight into various biotechnological applications.

Cdc7 is required throughout the yeast S phase to activate replication origins.

PubMed

Donaldson, A D; Fangman, W L; Brewer, B J

1998-02-15

The long-standing conclusion that the Cdc7 kinase of Saccharomyces cerevisiae is required only to trigger S phase has been challenged by recent data that suggests it acts directly on individual replication origins. We tested the possibility that early- and late-activated origins have different requirements for Cdc7 activity. Cells carrying a cdc7(ts) allele were first arrested in G1 at the cdc7 block by incubation at 37 degrees C, and then were allowed to enter S phase by brief incubation at 23 degrees C. During the S phase, after return to 37 degrees C, early-firing replication origins were activated, but late origins failed to fire. Similarly, a plasmid with a late-activated origin was defective in replication. As a consequence of the origin activation defect, duplication of chromosomal sequences that are normally replicated from late origins was greatly delayed. Early-replicating regions of the genome duplicated at approximately their normal time. The requirements of early and late origins for Cdc7 appear to be temporally rather than quantitatively different, as reducing overall levels of Cdc7 by growth at semi-permissive temperature reduced activation at early and late origins approximately equally. Our results show that Cdc7 activates early and late origins separately, with late origins requiring the activity later in S phase to permit replication initiation.

CLB5-dependent activation of late replication origins in S. cerevisiae.

PubMed

Donaldson, A D; Raghuraman, M K; Friedman, K L; Cross, F R; Brewer, B J; Fangman, W L

1998-08-01

Replication origins in chromosomes are activated at specific times during the S phase. We show that the B-type cyclins are required for proper execution of this temporal program. clb5 cells activate early origins but not late origins, explaining the previously described long clb5 S phase. Origin firing appears normal in cIb6 mutants. In clb5 clb6 double mutant cells, the late origin firing defect is suppressed, accounting for the normal duration of the phase despite its delayed onset. Therefore, Clb5p promotes the timely activation of early and late origins, but Clb6p can activate only early origins. In clb5 clb6 mutants, the other B-type cyclins (Clb1-4p) promote an S phase during which both early and late replication origins fire.

PPARα autocrine regulation of Ca²⁺-regulated exocytosis in guinea pig antral mucous cells: NO and cGMP accumulation.

PubMed

Tanaka, Saori; Sugiyama, Nanae; Takahashi, Yuko; Mantoku, Daiki; Sawabe, Yukinori; Kuwabara, Hiroko; Nakano, Takashi; Shimamoto, Chikao; Matsumura, Hitoshi; Marunaka, Yoshinori; Nakahari, Takashi

2014-12-15

In antral mucous cells, acetylcholine (ACh, 1 μM) activates Ca(2+)-regulated exocytosis, consisting of a peak in exocytotic events that declines rapidly (initial phase) followed by a second slower decline (late phase) lasting during ACh stimulation. GW7647 [a peroxisome proliferation activation receptor α (PPARα) agonist] enhanced the ACh-stimulated initial phase, and GW6471 (a PPARα antagonist) abolished the GW7647-induced enhancement. However, GW6471 produced the delayed, but transient, increase in the ACh-stimulated late phase, and it also decreased the initial phase and produced the delayed increase in the late phase during stimulation with ACh alone. A similar delayed increase in the ACh-stimulated late phase is induced by an inhibitor of the PKG, Rp8BrPETcGMPS, suggesting that GW6471 inhibits cGMP accumulation. An inhibitor of nitric oxide synthase 1 (NOS1), N(5)-[imino(propylamino)methyl]-L-ornithine hydrochloride (N-PLA), also abolished the GW7647-induced-enhancement of ACh-stimulated initial phase but produced the delayed increase in the late phase. However, in the presence of N-PLA, an NO donor or 8BrcGMP enhanced the ACh-stimulated initial phase and abolished the delayed increase in the late phase. Moreover, GW7647 and ACh stimulated NO production and cGMP accumulation in antral mucosae, which was inhibited by GW6471 or N-PLA. Western blotting and immunohistochemistry revealed that NOS1 and PPARα colocalize in antral mucous cells. In conclusion, during ACh stimulation, a PPARα autocrine mechanism, which accumulates NO via NOS1 leading to cGMP accumulation, modulates the Ca(2+)-regulated exocytosis in antral mucous cells. Copyright © 2014 the American Physiological Society.

Differences in activation properties of the hamstring muscles during overground sprinting.

PubMed

Higashihara, Ayako; Nagano, Yasuharu; Ono, Takashi; Fukubayashi, Toru

2015-09-01

The purpose of this study was to quantify activation of the biceps femoris (BF) and medial hamstring (MH) during overground sprinting. Lower-extremity kinematics and electromyography (EMG) of the BF and MH were recorded in 13 male sprinters performing overground sprinting at maximum effort. Mean EMG activity was calculated in the early stance, late stance, mid-swing, and late-swing phases. Activation of the BF was significantly greater during the early stance phase than the late stance phase (p<0.01). Activation of the BF muscle was significantly lower during the first half of the mid-swing phase than the other phases (p<0.05). The MH had significantly greater EMG activation relative to its recorded maximum values compared to that for the BF during the late stance (p<0.05) and mid-swing (p<0.01) phases. These results indicate that the BF shows high activation before and after foot contact, while the MH shows high activation during the late stance and mid-swing phases. We concluded that the activation properties of the BF and MH muscles differ within the sprinting gait cycle. Copyright © 2015 Elsevier B.V. All rights reserved.

Spatial and temporal trends in brominated flame retardants in seabirds from the Pacific coast of Canada.

PubMed

Miller, Aroha; Elliott, John E; Elliott, Kyle H; Guigueno, Mélanie F; Wilson, Laurie K; Lee, Sandi; Idrissi, Abde

2014-12-01

Polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD) are bioaccumulative flame retardants. PBDEs increased in many ecosystems during the late 20th century, but recently have declined in some environments. To examine trends in the northern Pacific, we analysed PBDEs, HBCDD and carbon and nitrogen stable isotopes (δ13C and δ15N) to account for dietary effects in archived eggs of three seabird species from British Columbia, Canada, 1990-2011 (rhinoceros auklets, Cerorhinca monocerata; Leach's storm-petrels, Oceanodroma leucorhoa; ancient murrelets, Synthliboramphus antiquus, 2009 only). PBDEs increased until approximately 2000 and then decreased, while HBCDD increased exponentially throughout the examined period. No significant changes in dietary tracers were observed. HBCDD and ΣPBDE levels varied among species; ΣPBDE also varied among sites. Temporal changes in contaminant concentrations are unlikely to have been caused by dietary changes, and likely reflect the build-up followed by decreases associated with voluntary phase-outs and regulations implemented in North America to control PBDEs. Crown Copyright © 2014. Published by Elsevier Ltd. All rights reserved.

Novel Antibacterial Activity of Lactococcus Lactis Subspecies Lactis Z11 Isolated from Zabady

PubMed Central

Enan, Gamal; Abdel-Shafi, Seham; Ouda, Sahar; Negm, Sally

2013-01-01

The purpose of this study was to select and characterize a probiotic bacterium with distinctive antimicrobial activities. In this respect, Lactococcus lactis subspecies lactis Z11 (L. lactis Z11) isolated from Zabady (Arabian yoghurt) inhibited other strains of lactic acid bacteria and some food-born pathogens including Listeria monocytogenes, Bacillus cereus and staphylococcus aureus. The inhibitory activity of cell free supernatant (CFS) of L. lactis Z11 isolated from zabady was lost by proteolytic enzymes, heat resistant. Consequently, the active substance(s) of CFS was characterized as a bacteriocin. This bacteriocin has been shown to consist of protein but has no lipidic or glucidic moieties in its active molecule. Its activity was stable in the pH range 2.0 to 7.0 and was not affected by organic solvents. The L. lactis Z11 bacteriocin was produced in CFS throughout the mide to the late exponential phase of growth of the producer organism and maximum bacteriocin production was obtained at initial pH 6.5 at incubation temperature of about 30°C. PMID:24151453

Late time acceleration of the 3-space in a higher dimensional steady state universe in dilaton gravity

NASA Astrophysics Data System (ADS)

Akarsu, Özgür; Dereli, Tekin

2013-02-01

We present cosmological solutions for (1+3+n)-dimensional steady state universe in dilaton gravity with an arbitrary dilaton coupling constant w and exponential dilaton self-interaction potentials in the string frame. We focus particularly on the class in which the 3-space expands with a time varying deceleration parameter. We discuss the number of the internal dimensions and the value of the dilaton coupling constant to determine the cases that are consistent with the observed universe and the primordial nucleosynthesis. The 3-space starts with a decelerated expansion rate and evolves into accelerated expansion phase subject to the values of w and n, but ends with a Big Rip in all cases. We discuss the cosmological evolution in further detail for the cases w = 1 and w = ½ that permit exact solutions. We also comment on how the universe would be conceived by an observer in four dimensions who is unaware of the internal dimensions and thinks that the conventional general relativity is valid at cosmological scales.

Poissonian renormalizations, exponentials, and power laws.

PubMed

Eliazar, Iddo

2013-05-01

This paper presents a comprehensive "renormalization study" of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to "white noise" and to "1/f noise." Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.

Effects of Nickel and Cobalt on Kinetics of Methanol Conversion by Methanogenic Sludge as Assessed by On-Line CH4 Monitoring

PubMed Central

Gonzalez-Gil, Graciela; Kleerebezem, Robbert; Lettinga, Gatze

1999-01-01

When metals were added in a pulse mode to methylotrophic-methanogenic biomass, three methane production rate phases were recognized. Increased concentrations of Ni and Co accelerated the initial exponential and final arithmetic increases in the methane production rate and reduced the temporary decrease in the rate. When Ni and Co were added continuously, the temporary decrease phase was eliminated and the exponential production rate increased. We hypothesize that the temporary decrease in the methane production rate and the final arithmetic increase in the methane production rate were due to micronutrient limitations and that the precipitation-dissolution kinetics of metal sulfides may play a key role in the biovailability of these compounds. PMID:10103284

Effects of nickel and cobalt on kinetics of methanol conversion by methanogenic sludge as assessed by on-line CH4 monitoring.

PubMed

Gonzalez-Gil, G; Kleerebezem, R; Lettinga, G

1999-04-01

When metals were added in a pulse mode to methylotrophic-methanogenic biomass, three methane production rate phases were recognized. Increased concentrations of Ni and Co accelerated the initial exponential and final arithmetic increases in the methane production rate and reduced the temporary decrease in the rate. When Ni and Co were added continuously, the temporary decrease phase was eliminated and the exponential production rate increased. We hypothesize that the temporary decrease in the methane production rate and the final arithmetic increase in the methane production rate were due to micronutrient limitations and that the precipitation-dissolution kinetics of metal sulfides may play a key role in the biovailability of these compounds.

Phase mixing of Alfvén waves in axisymmetric non-reflective magnetic plasma configurations

NASA Astrophysics Data System (ADS)

Petrukhin, N. S.; Ruderman, M. S.; Shurgalina, E. G.

2018-02-01

We study damping of phase-mixed Alfvén waves propagating in non-reflective axisymmetric magnetic plasma configurations. We derive the general equation describing the attenuation of the Alfvén wave amplitude. Then we applied the general theory to a particular case with the exponentially divergent magnetic field lines. The condition that the configuration is non-reflective determines the variation of the plasma density along the magnetic field lines. The density profiles exponentially decreasing with the height are not among non-reflective density profiles. However, we managed to find non-reflective profiles that fairly well approximate exponentially decreasing density. We calculate the variation of the total wave energy flux with the height for various values of shear viscosity. We found that to have a substantial amount of wave energy dissipated at the lower corona, one needs to increase shear viscosity by seven orders of magnitude in comparison with the value given by the classical plasma theory. An important result that we obtained is that the efficiency of the wave damping strongly depends on the density variation with the height. The stronger the density decrease, the weaker the wave damping is. On the basis of this result, we suggested a physical explanation of the phenomenon of the enhanced wave damping in equilibrium configurations with exponentially diverging magnetic field lines.

Design and verification of a highly reliable Linear-After-The-Exponential PCR (LATE-PCR) assay for the detection of African swine fever virus.

PubMed

Ronish, B; Hakhverdyan, M; Ståhl, K; Gallardo, C; Fernandez-Pinero, J; Belák, S; Leblanc, N; Wangh, L

2011-03-01

African swine fever virus (ASFV) is a highly pathogenic DNA virus that is the causative agent of African swine fever (ASF), an infectious disease of domestic and wild pigs of all breeds and ages, causing a range of syndromes. Acute disease is characterized by high fever, haemorrhages in the reticuloendothelial system, and a high mortality rate. A powerful novel diagnostic assay based on the Linear-After-The-Exponential-PCR (LATE-PCR) principle was developed to detect ASFV. LATE-PCR is an advanced form of asymmetric PCR which results in direct amplification of large amount of single-stranded DNA. Fluorescent readings are acquired using endpoint analysis after PCR amplification. Amplification of the correct product is verified by melting curve analysis. The assay was designed to amplify the VP72 gene of ASFV genome. Nineteen ASFV DNA cell culture virus strains and three tissue samples (spleen, tonsil, and liver) from infected experimental pigs were tested. Virus was detected in all of the cell culture and tissue samples. None of five ASFV-related viruses tested produced a positive signal, demonstrating the high specificity of the assay. The sensitivity of the LATE-PCR assay was determined in two separate real-time monoplex reactions using samples of synthetic ASFV and synthetic control-DNA targets that were diluted serially from 10⁹ to 1 initial copies per reaction. The detection limit was 1 and 10 copies/reaction, respectively. The sensitivity of the assay was also tested in a duplex end-point reactions comprised of a constant level of 150 copies of synthetic control-DNA and a clinical sample of spleen tissue diluted serially from 10⁻¹ to 10⁻⁵. The detection limit was 10⁻⁵ dilution which corresponds to approximately 1 copy/reaction. Since the assay is designed to be used in either laboratory settings or in a portable PCR machine (Bio-Seeq Portable Veterinary Diagnostics Laboratory; Smiths Detection, Watford UK), the LATE-PCR provides a robust and novel tool for the diagnosis of ASF both in the laboratory and in the field. Copyright © 2010 Elsevier B.V. All rights reserved.

Phase distribution of spliceosomal introns: implications for intron origin

PubMed Central

Nguyen, Hung D; Yoshihama, Maki; Kenmochi, Naoya

2006-01-01

Background The origin of spliceosomal introns is the central subject of the introns-early versus introns-late debate. The distribution of intron phases is non-uniform, with an excess of phase-0 introns. Introns-early explains this by speculating that a fraction of present-day introns were present between minigenes in the progenote and therefore must lie in phase-0. In contrast, introns-late predicts that the nonuniformity of intron phase distribution reflects the nonrandomness of intron insertions. Results In this paper, we tested the two theories using analyses of intron phase distribution. We inferred the evolution of intron phase distribution from a dataset of 684 gene orthologs from seven eukaryotes using a maximum likelihood method. We also tested whether the observed intron phase distributions from 10 eukaryotes can be explained by intron insertions on a genome-wide scale. In contrast to the prediction of introns-early, the inferred evolution of intron phase distribution showed that the proportion of phase-0 introns increased over evolution. Consistent with introns-late, the observed intron phase distributions matched those predicted by an intron insertion model quite well. Conclusion Our results strongly support the introns-late hypothesis of the origin of spliceosomal introns. PMID:16959043

Determining the Kinetic Parameters Characteristic of Microalgal Growth.

ERIC Educational Resources Information Center

Martinez Sancho, Maria Eugenie; And Others

1991-01-01

An activity in which students obtain a growth curve for algae, identify the exponential and linear growth phases, and calculate the parameters which characterize both phases is described. The procedure, a list of required materials, experimental conditions, analytical technique, and a discussion of the interpretations of individual results are…

Time indices of multiphasic development in genotypes of sweet cherry are similar from dormancy to cessation of pit growth.

PubMed

Gibeaut, David M; Whiting, Matthew D; Einhorn, Todd

2017-02-01

The archetypical double sigmoid-shaped growth curve of the sweet cherry drupe (Prunus avium) does not address critical development from eco-dormancy to anthesis and has not been correlated to reproductive bud development. Accurate representation of the growth and development of post-anthesis ovaries is confounded by anthesis timing, fruiting-density and the presence of unfertilized and defective ovaries whose growth differs from those that persist to maturation. These factors were addressed to assess pre-anthesis and full-season growth and development of three sweet cherry cultivars, 'Chelan', 'Bing' and 'Sweetheart', differing primarily in seasonal duration and fruit size. Volume was calculated from photographic measurements of reproductive buds, ovaries and pits at all phases of development. A population of unfertilized ovaries was produced using bee-exclusion netting to enable a statistical comparison with an open pollinated population to detect differences in size and shape between successful and failing fruit growth. Anthesis timing and fruiting-density were manipulated by floral extinction at the spur and whole-tree scales. Developmental time indices were analysed using polynomial curve fitting of log-transformed data supported by Richards and logistic functions of asymptotic growth of the pit and maturing fruit, respectively. Pre-anthesis growth began at the completion of eco-dormancy. A slight decline in relative growth rate (RGR) was observed during bud scale separation approx. -16 d from anthesis (DFA) before resumption of exponential growth to a maximum about 14 DFA. After anthesis, reduced growth of unfertilized or defective ovaries was partly discriminated from successful fruit at 5 DFA and completely at 25 DFA. Time indices of RGR inflections were similar among cultivars when adjusted for anthesis date alone, until the end of pit growth. Asymptotic growth of the pit underpinned the declining growth rate of fruit at the end of the first exponential growth phase. Duration of the subsequent expansive growth phase accounted for genotypic differences in seasonal duration and final size. Pit size and final fruit size were inversely related to fruiting-density. Developmental differences among early, mid and late maturing cultivars were not detected until the final growth period. © The Author 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Time indices of multiphasic development in genotypes of sweet cherry are similar from dormancy to cessation of pit growth

PubMed Central

Gibeaut, David M.; Whiting, Matthew D.; Einhorn, Todd

2017-01-01

Background and Aims The archetypical double sigmoid-shaped growth curve of the sweet cherry drupe (Prunus avium) does not address critical development from eco-dormancy to anthesis and has not been correlated to reproductive bud development. Accurate representation of the growth and development of post-anthesis ovaries is confounded by anthesis timing, fruiting-density and the presence of unfertilized and defective ovaries whose growth differs from those that persist to maturation. These factors were addressed to assess pre-anthesis and full-season growth and development of three sweet cherry cultivars, ‘Chelan’, ‘Bing’ and ‘Sweetheart’, differing primarily in seasonal duration and fruit size. Methods Volume was calculated from photographic measurements of reproductive buds, ovaries and pits at all phases of development. A population of unfertilized ovaries was produced using bee-exclusion netting to enable a statistical comparison with an open pollinated population to detect differences in size and shape between successful and failing fruit growth. Anthesis timing and fruiting-density were manipulated by floral extinction at the spur and whole-tree scales. Developmental time indices were analysed using polynomial curve fitting of log-transformed data supported by Richards and logistic functions of asymptotic growth of the pit and maturing fruit, respectively. Key Results Pre-anthesis growth began at the completion of eco-dormancy. A slight decline in relative growth rate (RGR) was observed during bud scale separation approx. −16 d from anthesis (DFA) before resumption of exponential growth to a maximum about 14 DFA. After anthesis, reduced growth of unfertilized or defective ovaries was partly discriminated from successful fruit at 5 DFA and completely at 25 DFA. Time indices of RGR inflections were similar among cultivars when adjusted for anthesis date alone, until the end of pit growth. Asymptotic growth of the pit underpinned the declining growth rate of fruit at the end of the first exponential growth phase. Duration of the subsequent expansive growth phase accounted for genotypic differences in seasonal duration and final size. Pit size and final fruit size were inversely related to fruiting-density. Conclusions Developmental differences among early, mid and late maturing cultivars were not detected until the final growth period. PMID:28064193

Investigating gas-phase defect formation in late-stage solidification using a novel phase-field crystal alloy model

NASA Astrophysics Data System (ADS)

Wang, Nan; Smith, Nathan; Provatas, Nikolas

2017-09-01

We study late-stage solidification and the associated formation of defects in alloy materials using a novel model based on the phase-field-crystal technique. It is shown that our model successfully captures several important physical phenomena that occur in the late stages of solidification, including solidification shrinkage, liquid cavitation and microsegregation, all in a single framework. By examining the interplay of solidification shrinkage and solute segregation, this model reveals that the formation of gas pore defects at the late stage of solidification can lead to nucleation of second phase solid particles due to solute enrichment in the eutectic liquid driven by gas-phase nucleation and growth. We also predict a modification of the Gulliver-Scheil equation in the presence of gas pockets in confined liquid pools.

Age-Related Enhancement of a Protein Synthesis-Dependent Late Phase of LTP Induced by Low Frequency Paired-Pulse Stimulation in Hippocampus

ERIC Educational Resources Information Center

Huang, Yan-You; Kandel, Eric R.

2006-01-01

Protein synthesis-dependent late phase of LTP (L-LTP) is typically induced by repeated high-frequency stimulation (HFS). This form of L-LTP is reduced in the aged animal and is positively correlated with age-related memory loss. Here we report a novel form of protein synthesis-dependent late phase of LTP in the CA1 region of hippocampus induced by…

Proteomic Analysis of Stationary Phase in the Marine Bacterium "Candidatus Pelagibacter ubique"

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

Sowell, S. M.; Norbeck, A. D.; Lipton, M. S.

2008-05-09

The α-proteobacterium ‘Candidatus Pelagibacter ubique’ str. HTCC1062, and most other members of the SAR11 clade, lack genes for assimilatory sulfate reduction, making them dependent on organosulfur compounds that occur naturally in seawater. To investigate how these cells adapt to sulfur limitation, batch cultures were grown in defined media containing either limiting or non-limiting amounts of dimethylsulfoniopropionate (DMSP) as the sole sulfur source. Protein and mRNA expression were measured during exponential growth, immediately prior to stationary phase, and in late stationary phase. Two distinct responses were observed: one as DMSP became exhausted, and another as cells acclimated to a sulfur-limited environment.more » The first response was characterized by increased transcription and translation of all Ca. P. ubique genes downstream of previously confirmed S-adenosyl methionine (SAM) riboswitches: bhmT, mmuM, and metY. Proteins encoded by these genes were up to 33 times more abundant as DMSP became limiting. Their predicted function is to shunt all available sulfur to methionine. The secondary response, observed during sulfur-depleted stationary phase, was a 6-10 fold increase in transcription of the heme c shuttle ccmC and two small genes of unknown function (SAR11_1163 and SAR11_1164). This bacterium's strategy for coping with sulfur stress appears to be intracellular redistribution to support methionine biosynthesis, rather than increasing organosulfur import. Many of the genes and SAM riboswitches involved in this response are located in a hypervariable genome region (HVR). One of these HVR genes, ordL, is located downstream of a conserved motif that evidence suggests is a novel riboswitch.« less

Methane exchange at the peatland forest floor - automatic chamber system exposes the dynamics of small fluxes

NASA Astrophysics Data System (ADS)

Korkiakoski, Mika; Tuovinen, Juha-Pekka; Aurela, Mika; Koskinen, Markku; Minkkinen, Kari; Ojanen, Paavo; Penttilä, Timo; Rainne, Juuso; Laurila, Tuomas; Lohila, Annalea

2017-04-01

We measured methane (CH4) exchange rates with automatic chambers at the forest floor of a nutrient-rich drained peatland in 2011-2013. The fen, located in southern Finland, was drained for forestry in 1969 and the tree stand is now a mixture of Scots pine, Norway spruce, and pubescent birch. Our measurement system consisted of six transparent chambers and stainless steel frames, positioned on a number of different field and moss layer compositions. Gas concentrations were measured with an online cavity ring-down spectroscopy gas analyzer. Fluxes were calculated with both linear and exponential regression. The use of linear regression resulted in systematically smaller CH4 fluxes by 10-45 % as compared to exponential regression. However, the use of exponential regression with small fluxes ( < 2.5 µg CH4 m-2 h-1) typically resulted in anomalously large absolute fluxes and high hour-to-hour deviations. Therefore, we recommend that fluxes are initially calculated with linear regression to determine the threshold for low fluxes and that higher fluxes are then recalculated using exponential regression. The exponential flux was clearly affected by the length of the fitting period when this period was < 190 s, but stabilized with longer periods. Thus, we also recommend the use of a fitting period of several minutes to stabilize the results and decrease the flux detection limit. There were clear seasonal dynamics in the CH4 flux: the forest floor acted as a CH4 sink particularly from early summer until the end of the year, while in late winter the flux was very small and fluctuated around zero. However, the magnitude of fluxes was relatively small throughout the year, ranging mainly from -130 to +100 µg CH4 m-2 h-1. CH4 emission peaks were observed occasionally, mostly in summer during heavy rainfall events. Diurnal variation, showing a lower CH4 uptake rate during the daytime, was observed in all of the chambers, mainly in the summer and late spring, particularly in dry conditions. It was attributed more to changes in wind speed than air or soil temperature, which suggest that physical rather than biological phenomena are responsible for the observed variation. The annual net CH4 exchange varied from -104 ± 30 to -505 ± 39 mg CH4 m-2 yr-1 among the six chambers, with an average of -219 mg CH4 m-2 yr-1 over the 2-year measurement period.

Production of volatile organic compounds by cyanobacteria Synechococcus sp.

NASA Astrophysics Data System (ADS)

Hiraiwa, M.; Abe, M.; Hashimoto, S.

2014-12-01

Phytoplankton are known to produce volatile organic compounds (VOCs), which contribute to environmental problems such as global warming and decomposition of stratospheric ozone. For example, picophytoplankton, such as Prochlorococcus and Synechococcus, are distributed in freshwater and oceans worldwide, accounting for a large proportion of biomass and primary production in the open ocean. However, to date, little is known about the production of VOCs by picophytoplankton. In this study, VOCs production by cyanobacteria Synechococcus sp. (NIES-981) was investigated. Synechococcus sp. was obtained from the National Institute for Environmental Studies (NIES), Japan, and cultured at 24°C in autoclaved f/2-Si medium under 54 ± 3 µE m-2 s-1 (1 E = 1 mol of photons) with a 12-h light and 12-h dark cycle. VOCs concentrations were determined using a purge-and-trap gas chromatograph-mass spectrometer (Agilent 5973). The concentrations of chlorophyll a (Chl a) were also determined using a fluorometer (Turner TD-700). Bromomethane (CH3Br) and isoprene were produced by Synechococcus sp. Isoprene production was similar to those of other phytoplankton species reported earlier. Isoprene was produced when Chl a was increasing in the early stage of the incubation period (5-15 days of incubation time, exponential phase), but CH3Br was produced when Chl a was reduced in the late stage of the incubation period (30-40 days of incubation time, death phase).

A Long-Lived Oscillatory Space-Time Correlation Function of Two Dimensional Colloids

NASA Astrophysics Data System (ADS)

Kim, Jeongmin; Sung, Bong June

2014-03-01

Diffusion of a colloid in solution has drawn significant attention for a century. A well-known behavior of the colloid is called Brownian motion : the particle displacement probability distribution (PDPD) is Gaussian and the mean-square displacement (MSD) is linear with time. However, recent simulation and experimental studies revealed the heterogeneous dynamics of colloids near glass transitions or in complex environments such as entangled actin, PDPD exhibited the exponential tail at a large length instead of being Gaussian at all length scales. More interestingly, PDPD is still exponential even when MSD was still linear with time. It requires a refreshing insight on the colloidal diffusion in the complex environments. In this work, we study heterogeneous dynamics of two dimensional (2D) colloids using molecular dynamics simulations. Unlike in three dimensions, 2D solids do not follow the Lindemann melting criterion. The Kosterlitz-Thouless-Halperin-Nelson-Young theory predicts two-step phase transitions with an intermediate phase, the hexatic phase between isotropic liquids and solids. Near solid-hexatic transition, PDPD shows interesting oscillatory behavior between a central Gaussian part and an exponential tail. Until 12 times longer than translational relaxation time, the oscillatory behavior still persists even after entering the Fickian regime. We also show that multi-layered kinetic clusters account for heterogeneous dynamics of 2D colloids with the long-lived anomalous oscillatory PDPD.

Magnetic confinement, Alfven wave reflection, and the origins of X-ray and mass-loss 'dividing lines' for late-type giants and supergiants

NASA Technical Reports Server (NTRS)

Rosner, R.; An, C.-H.; Musielak, Z. E.; Moore, R. L.; Suess, S. T.

1991-01-01

A simple qualitative model for the origin of the coronal and mass-loss dividing lines separating late-type giants and supergiants with and without hot, X-ray-emitting corona, and with and without significant mass loss is discussed. The basic physical effects considered are the necessity of magnetic confinement for hot coronal material on the surface of such stars and the large reflection efficiency for Alfven waves in cool exponential atmospheres. The model assumes that the magnetic field geometry of these stars changes across the observed 'dividing lines' from being mostly closed on the high effective temperature side to being mostly open on the low effective temperature side.

Feasibility of protein turnover studies in prototroph Saccharomyces cerevisiae strains.

PubMed

Martin-Perez, Miguel; Villén, Judit

2015-04-07

Quantitative proteomics studies of yeast that use metabolic labeling with amino acids rely on auxotrophic mutations of one or more genes on the amino acid biosynthesis pathways. These mutations affect yeast metabolism and preclude the study of some biological processes. Overcoming this limitation, it has recently been described that proteins in a yeast prototrophic strain can also be metabolically labeled with heavy amino acids. However, the temporal profiles of label incorporation under the different phases of the prototroph's growth have not been examined. Labeling trajectories are important in the study of protein turnover and dynamics, in which label incorporation into proteins is monitored across many time points. Here we monitored protein labeling trajectories for 48 h after a pulse with heavy lysine in a yeast prototrophic strain and compared them with those of a lysine auxotrophic yeast. Labeling was successful in prototroph yeast during exponential growth phase but not in stationary phase. Furthermore, we were able to determine the half-lives of more than 1700 proteins during exponential phase of growth with high accuracy and reproducibility. We found a median half-life of 2 h in both strains, which corresponds with the cellular doubling time. Nucleolar and ribosomal proteins showed short half-lives, whereas mitochondrial proteins and other energy production enzymes presented longer half-lives. Except for some proteins involved in lysine biosynthesis, we observed a high correlation in protein half-lives between prototroph and auxotroph strains. Overall, our results demonstrate the feasibility of using prototrophs for proteomic turnover studies and provide a reliable data set of protein half-lives in exponentially growing yeast.

Particulate and Dissolved Organic Carbon Production by the Heterotrophic Nanoflagellate Pteridomonas danica Patterson and Fenchel.

PubMed

Pelegrí; Christaki; Dolan; Rassoulzadegan

1999-05-01

> Abstract We established a budget of organic carbon utilization of a starved heterotrophic nanoflagellate, Pteridomonas danica, incubated in batch cultures with Escherichia coli as model prey. The cultures were sampled periodically for biomass determinations and total organic carbon dynamics: total organic carbon, total organic carbon <1 µm, and dissolved organic carbon (DOC, <0.2 µm). During the 22 h incubation period, P. danica underwent biovolume variations of 3.2-fold. Gross growth efficiency was 22% and net growth efficiency 40%. P. danica respired 33% and egested 44% of the ingested E. coli carbon during lag and exponential growth phases. The form of the organic carbon egested varied. Of the total ingested carbon, 9% was egested in the form of DOC and occurred mainly during the exponential growth phase; 35% was egested in the form of particulate organic carbon (POC), ranging in size from 0.2 to 1 µm, and took place during the lag phase. P. danica could have reingested as much of 58% of this previously produced POC during the exponential growth phase as food scarcity increased. We concluded that POC egestion by flagellates could represent a significant source of submicrometric particles and colloidal organic matter. In addition, flagellate reingestion of egested POC could play a nonnegligible role in the microbial food web. Finally, the methodology reported in this study has proved to be a useful tool in the study of carbon metabolism in aquatic microorganisms.http://link.springer-ny.com/link/service/journals/00248/bibs/37n4p276.html

The mediation effect of menstrual phase on negative emotion processing: evidence from N2.

PubMed

Wu, Haiyan; Chen, Chunping; Cheng, Dazhi; Yang, Suyong; Huang, Ruiwang; Cacioppo, Stephanie; Luo, Yue-Jia

2014-01-01

Numerous studies have shown a 'negativity bias' in emotion processing and effect of menstrual phase on emotion processing. Most of these results, however, did not match the arousal of different types of stimuli. The present study examined the time course of negative emotion processing across different menstrual phases (e.g., late luteal/premenstrual phase and follicular phase) when the arousal level of negative and neutral stimuli was equal. Following previous studies, an oddball paradigm was utilized in present study. Participants viewed neutral and negative (highly (HN) and moderately negative (MN)) stimuli with matched arousal and were asked to make deviant vs. standard judgments. The behavioral results showed a higher accuracy for HN stimuli than neutral stimuli, and the other comparisons were not significant. The major event-related potential (ERP) finding was that N2 amplitude was larger for MN than neutral in the late luteal phase, whereas such difference was absent during the follicular phase. Moreover, The N2 for HN stimuli was larger in late luteal phase than in follicular phase. Therefore, female may be with higher sensitivity to MN stimuli during late luteal phase than during follicular phase when the arousal of stimuli was well controlled. These results provide additional insight to premenstrual affective syndrome and affective disorder.

Protein synthesis and the recovery of both survival and cytoplasmic "petite" mutation in ultraviolet-treated yeast cells. II. Mitochondrial protein synthesis.

PubMed

Heude, M; Chanet, R

1975-04-01

The contribution of mitochondrial proteins in the repair of UV-induced lethal and cytoplasmic genetic damages was studied in dark liquid held exponential and stationary phase yeast cells. This was performed by using the specific inhibitors, erythromycin (ER) anc chloramphenicol (CAP). It was shown that mitochondrial proteins are involved in the recovery of stationary phase cells. Mitochondrial proteins are partly implicated in the mechanisms leading to the restoration of the (see article) genotype in UV-irradiated dark liquid held exponential phase cells. Here again, in stationary phase cells, mitochondrial enzymes do not seem to participate in the negative liquid holding (NLH) process for the (see article) induction, as shown by inhibiting mitochondrial protein synthesis or both mitochondrial and nuclear protein synthesis. When cells are grown in glycerol, the response after dark liquid holding of UV-treated cells in the different growth stages are similar to that found for glucose-grown cells. In other words, the fate of cytoplasmic genetic damage, in particular, is not correlated with the repressed or derepressed state of the mitochondria.

Poissonian renormalizations, exponentials, and power laws

NASA Astrophysics Data System (ADS)

Eliazar, Iddo

2013-05-01

This paper presents a comprehensive “renormalization study” of Poisson processes governed by exponential and power-law intensities. These Poisson processes are of fundamental importance, as they constitute the very bedrock of the universal extreme-value laws of Gumbel, Fréchet, and Weibull. Applying the method of Poissonian renormalization we analyze the emergence of these Poisson processes, unveil their intrinsic dynamical structures, determine their domains of attraction, and characterize their structural phase transitions. These structural phase transitions are shown to be governed by uniform and harmonic intensities, to have universal domains of attraction, to uniquely display intrinsic invariance, and to be intimately connected to “white noise” and to “1/f noise.” Thus, we establish a Poissonian explanation to the omnipresence of white and 1/f noises.

Increasing fermentation efficiency at high sugar concentrations by supplementing an additional source of nitrogen during the exponential phase of the tequila fermentation process.

PubMed

Arrizon, Javier; Gschaedler, Anne

2002-11-01

In the tequila industry, fermentation is traditionally achieved at sugar concentrations ranging from 50 to 100 g x L(-1). In this work, the behaviour of the Saccharomyces cerevisiae yeast (isolated from the juices of the Agave tequilana Weber blue variety) during the agave juice fermentation is compared at different sugar concentrations to determine if it is feasible for the industry to run fermentation at higher sugar concentrations. Fermentation efficiency is shown to be higher (above 90%) at a high concentration of initial sugar (170 g x L(-1)) when an additional source of nitrogen (a mixture of amino acids and ammonium sulphate, different than a grape must nitrogen composition) is added during the exponential growth phase.

Analytical Description of Degradation-Relaxation Transformations in Nanoinhomogeneous Spinel Ceramics.

PubMed

Shpotyuk, O; Brunner, M; Hadzaman, I; Balitska, V; Klym, H

2016-12-01

Mathematical models of degradation-relaxation kinetics are considered for jammed thick-film systems composed of screen-printed spinel Cu 0.1 Ni 0.1 Co 1.6 Mn 1.2 O 4 and conductive Ag or Ag-Pd alloys. Structurally intrinsic nanoinhomogeneous ceramics due to Ag and Ag-Pd diffusing agents embedded in a spinel phase environment are shown to define governing kinetics of thermally induced degradation under 170 °C obeying an obvious non-exponential behavior in a negative relative resistance drift. The characteristic stretched-to-compressed exponential crossover is detected for degradation-relaxation kinetics in thick-film systems with conductive contacts made of Ag-Pd and Ag alloys. Under essential migration of a conductive phase, Ag penetrates thick-film spinel ceramics via a considerable two-step diffusing process.

Investigating Marine Dissolved Organic Matter Fluorescence Transformations with Organic Geochemical Proxies in a Growth and Degradation Experiment using Amino Acids, Amino Sugars, and Phenols

NASA Astrophysics Data System (ADS)

Shields, M. R.; Bianchi, T. S.; Osburn, C. L.; Kinsey, J. D.; Ziervogel, K.; Schnetzer, A.

2017-12-01

The origin and mechanisms driving the formation of fluorescent dissolved organic matter (FDOM) in the open ocean remain unclear. Although recent studies have attempted to deconvolve the chemical composition and source of marine FDOM, these studies have been qualitative in nature. Here, we investigate these transformations using a more quantitative biomarker approach in a controlled growth and degradation experiment. In this experiment, a natural assemblage of phytoplankton was collected off the coast of North Carolina and incubated within roller bottles containing 0.2 µm-filtered North Atlantic surface water amended with f/2 nutrients. Samples were collected at the beginning (day 0), during exponential growth (day 13), stationary (day 20), and degradation (day 62) phases of the phytoplankton incubation. Amino acids, amino sugars, and phenolic compounds of the dissolved (DOM) were measured in conjunction with enzyme assays and bacterial counts to track shifts in OM quality as FDOM formed and was then transformed throughout the experiment. The results from the chemical analyses showed that the OM composition changed significantly from the initial and exponential phases to the stationary and degradation phases of the experiment. The percentage of aromatic amino acids to the total amino acid pool increased significantly during the exponential phase of phytoplankton growth, but then decreased significantly during the stationary and degradation phases. This increase was positively correlated to the fractional contribution of the protein-like peak in fluorescence to the total FDOM fluorescence. An increase in the concentration of amino acid degradation products during the stationary and degradation phases suggests that compositional changes in OM were driven by microbial transformation. This was further supported by a concurrent increase in total enzyme activity and increase in "humic-like" components of the FDOM. These findings link the properties and formation of FDOM to the overall quality and diagenetic state of marine OM and to the marine carbon and nitrogen cycles.

Higher-order phase transitions on financial markets

NASA Astrophysics Data System (ADS)

Kasprzak, A.; Kutner, R.; Perelló, J.; Masoliver, J.

2010-08-01

Statistical and thermodynamic properties of the anomalous multifractal structure of random interevent (or intertransaction) times were thoroughly studied by using the extended continuous-time random walk (CTRW) formalism of Montroll, Weiss, Scher, and Lax. Although this formalism is quite general (and can be applied to any interhuman communication with nontrivial priority), we consider it in the context of a financial market where heterogeneous agent activities can occur within a wide spectrum of time scales. As the main general consequence, we found (by additionally using the Saddle-Point Approximation) the scaling or power-dependent form of the partition function, Z(q'). It diverges for any negative scaling powers q' (which justifies the name anomalous) while for positive ones it shows the scaling with the general exponent τ(q'). This exponent is the nonanalytic (singular) or noninteger power of q', which is one of the pilar of higher-order phase transitions. In definition of the partition function we used the pausing-time distribution (PTD) as the central one, which takes the form of convolution (or superstatistics used, e.g. for describing turbulence as well as the financial market). Its integral kernel is given by the stretched exponential distribution (often used in disordered systems). This kernel extends both the exponential distribution assumed in the original version of the CTRW formalism (for description of the transient photocurrent measured in amorphous glassy material) as well as the Gaussian one sometimes used in this context (e.g. for diffusion of hydrogen in amorphous metals or for aging effects in glasses). Our most important finding is the third- and higher-order phase transitions, which can be roughly interpreted as transitions between the phase where high frequency trading is most visible and the phase defined by low frequency trading. The specific order of the phase transition directly depends upon the shape exponent α defining the stretched exponential integral kernel. On this basis a simple practical hint for investors was formulated.

Evidence of the Exponential Decay Emission in the Swift Gamma-ray Bursts

NASA Technical Reports Server (NTRS)

Sakamoto, T.; Sato, G.; Hill, J.E.; Krimm, H.A.; Yamazaki, R.; Takami, K.; Swindell, S.; Osborne, J.P.

2007-01-01

We present a systematic study of the steep decay emission of gamma-ray bursts (GRBs) observed by the Swift X-Ray Telescope (XRT). In contrast to the analysis in recent literature, instead of extrapolating the data of Burst Alert Telescope (BAT) down into the XRT energy range, we extrapolated the XRT data up to the BAT energy range, 15-25 keV, to produce the BAT and XRT composite light curve. Based on our composite light curve fitting, we have confirmed the existence of an exponential decay component which smoothly connects the BAT prompt data to the XRT steep decay for several GRBs. We also find that the XRT steep decay for some of the bursts can be well fitted by a combination of a power-law with an exponential decay model. We discuss that this exponential component may be the emission from an external shock and a sign of the deceleration of the outflow during the prompt phase.

Fast and accurate fitting and filtering of noisy exponentials in Legendre space.

PubMed

Bao, Guobin; Schild, Detlev

2014-01-01

The parameters of experimentally obtained exponentials are usually found by least-squares fitting methods. Essentially, this is done by minimizing the mean squares sum of the differences between the data, most often a function of time, and a parameter-defined model function. Here we delineate a novel method where the noisy data are represented and analyzed in the space of Legendre polynomials. This is advantageous in several respects. First, parameter retrieval in the Legendre domain is typically two orders of magnitude faster than direct fitting in the time domain. Second, data fitting in a low-dimensional Legendre space yields estimates for amplitudes and time constants which are, on the average, more precise compared to least-squares-fitting with equal weights in the time domain. Third, the Legendre analysis of two exponentials gives satisfactory estimates in parameter ranges where least-squares-fitting in the time domain typically fails. Finally, filtering exponentials in the domain of Legendre polynomials leads to marked noise removal without the phase shift characteristic for conventional lowpass filters.

T7 phage factor required for managing RpoS in Escherichia coli.

PubMed

Tabib-Salazar, Aline; Liu, Bing; Barker, Declan; Burchell, Lynn; Qimron, Udi; Matthews, Steve J; Wigneshweraraj, Sivaramesh

2018-06-05

T7 development in Escherichia coli requires the inhibition of the housekeeping form of the bacterial RNA polymerase (RNAP), Eσ 70 , by two T7 proteins: Gp2 and Gp5.7. Although the biological role of Gp2 is well understood, that of Gp5.7 remains to be fully deciphered. Here, we present results from functional and structural analyses to reveal that Gp5.7 primarily serves to inhibit Eσ S , the predominant form of the RNAP in the stationary phase of growth, which accumulates in exponentially growing E. coli as a consequence of the buildup of guanosine pentaphosphate [(p)ppGpp] during T7 development. We further demonstrate a requirement of Gp5.7 for T7 development in E. coli cells in the stationary phase of growth. Our finding represents a paradigm for how some lytic phages have evolved distinct mechanisms to inhibit the bacterial transcription machinery to facilitate phage development in bacteria in the exponential and stationary phases of growth.

Stretched exponential dynamics of coupled logistic maps on a small-world network

NASA Astrophysics Data System (ADS)

Mahajan, Ashwini V.; Gade, Prashant M.

2018-02-01

We investigate the dynamic phase transition from partially or fully arrested state to spatiotemporal chaos in coupled logistic maps on a small-world network. Persistence of local variables in a coarse grained sense acts as an excellent order parameter to study this transition. We investigate the phase diagram by varying coupling strength and small-world rewiring probability p of nonlocal connections. The persistent region is a compact region bounded by two critical lines where band-merging crisis occurs. On one critical line, the persistent sites shows a nonexponential (stretched exponential) decay for all p while for another one, it shows crossover from nonexponential to exponential behavior as p → 1 . With an effectively antiferromagnetic coupling, coupling to two neighbors on either side leads to exchange frustration. Apart from exchange frustration, non-bipartite topology and nonlocal couplings in a small-world network could be a reason for anomalous relaxation. The distribution of trap times in asymptotic regime has a long tail as well. The dependence of temporal evolution of persistence on initial conditions is studied and a scaling form for persistence after waiting time is proposed. We present a simple possible model for this behavior.

Molecular sensing using monolayer floating gate, fully depleted SOI MOSFET acting as an exponential transducer.

PubMed

Takulapalli, Bharath R

2010-02-23

Field-effect transistor-based chemical sensors fall into two broad categories based on the principle of signal transduction-chemiresistor or Schottky-type devices and MOSFET or inversion-type devices. In this paper, we report a new inversion-type device concept-fully depleted exponentially coupled (FDEC) sensor, using molecular monolayer floating gate fully depleted silicon on insulator (SOI) MOSFET. Molecular binding at the chemical-sensitive surface lowers the threshold voltage of the device inversion channel due to a unique capacitive charge-coupling mechanism involving interface defect states, causing an exponential increase in the inversion channel current. This response of the device is in opposite direction when compared to typical MOSFET-type sensors, wherein inversion current decreases in a conventional n-channel sensor device upon addition of negative charge to the chemical-sensitive device surface. The new sensor architecture enables ultrahigh sensitivity along with extraordinary selectivity. We propose the new sensor concept with the aid of analytical equations and present results from our experiments in liquid phase and gas phase to demonstrate the new principle of signal transduction. We present data from numerical simulations to further support our theory.

Saturation capability of short phase modulated pulses facilitates the measurement of longitudinal relaxation times of quadrupolar nuclei.

PubMed

Makrinich, Maria; Gupta, Rupal; Polenova, Tatyana; Goldbourt, Amir

The ability of various pulse types, which are commonly applied for distance measurements, to saturate or invert quadrupolar spin polarization has been compared by observing their effect on magnetization recovery curves under magic-angle spinning. A selective central transition inversion pulse yields a bi-exponential recovery for a diamagnetic sample with a spin-3/2, consistent with the existence of two processes: the fluctuations of the electric field gradients with identical single (W 1 ) and double (W 2 ) quantum quadrupolar-driven relaxation rates, and spin exchange between the central transition of one spin and satellite transitions of a dipolar-coupled similar spin. Using a phase modulated pulse, developed for distance measurements in quadrupolar spins (Nimerovsky et al., JMR 244, 2014, 107-113) and suggested for achieving the complete saturation of all quadrupolar spin energy levels, a mono-exponential relaxation model fits the data, compatible with elimination of the spin exchange processes. Other pulses such as an adiabatic pulse lasting one-third of a rotor period, and a two-rotor-period long continuous-wave pulse, both used for distance measurements under special experimental conditions, yield good fits to bi-exponential functions with varying coefficients and time constants due to variations in initial conditions. Those values are a measure of the extent of saturation obtained from these pulses. An empirical fit of the recovery curves to a stretched exponential function can provide general recovery times. A stretching parameter very close to unity, as obtained for a phase modulated pulse but not for other cases, suggests that in this case recovery times and longitudinal relaxation times are similar. The results are experimentally demonstrated for compounds containing 11 B (spin-3/2) and 51 V (spin-7/2). We propose that accurate spin lattice relaxation rates can be measured by a short phase modulated pulse (<1-2ms), similarly to the "true T 1 " measured by saturation with an asynchronous pulse train (Yesinowski, JMR 252, 2015, 135-144). Copyright © 2017 Elsevier Inc. All rights reserved.

Photoluminescence study of MBE grown InGaN with intentional indium segregation

NASA Astrophysics Data System (ADS)

Cheung, Maurice C.; Namkoong, Gon; Chen, Fei; Furis, Madalina; Pudavar, Haridas E.; Cartwright, Alexander N.; Doolittle, W. Alan

2005-05-01

Proper control of MBE growth conditions has yielded an In0.13Ga0.87N thin film sample with emission consistent with In-segregation. The photoluminescence (PL) from this epilayer showed multiple emission components. Moreover, temperature and power dependent studies of the PL demonstrated that two of the components were excitonic in nature and consistent with indium phase separation. At 15 K, time resolved PL showed a non-exponential PL decay that was well fitted with the stretched exponential solution expected for disordered systems. Consistent with the assumed carrier hopping mechanism of this model, the effective lifetime, , and the stretched exponential parameter, , decrease with increasing emission energy. Finally, room temperature micro-PL using a confocal microscope showed spatial clustering of low energy emission.

Differential Response Pattern of Oropharyngeal Pressure by Bolus and Dry Swallows.

PubMed

Hasegawa, Mana; Kurose, Masayuki; Okamoto, Keiichiro; Yamada, Yoshiaki; Tsujimura, Takanori; Inoue, Makoto; Sato, Taisuke; Narumi, Takatsune; Fujii, Noritaka; Yamamura, Kensuke

2018-02-01

The aim of this study was to determine if bolus and dry swallow showed similar pressure changes in the oropharynx using our newly developed device. A unique character of it includes that baropressure can be measured with the sensor being placed in the balloon and can assess the swallowing mechanics in terms of pressure changes in the oropharynx with less influences of direct contacts of boluses and oropharyngeal structures during swallow indirectly. Fifteen healthy subjects swallowed saliva (dry), 15 ml of water, 45 ml of water, and 15 ml of two different types of food in terms of viscosity (potage soup-type and mayonnaise-type foods). Suprahyoid muscle activity was recorded simultaneously. Three parameters, area under the curve (AUC), peak amplitude, and duration of pressure, were analyzed from each swallow. Almost all of the bolus swallowing events had biphasic baropressure responses consisting of an early phase and late phase (99%), whereas 90% of the saliva swallowing events had a single phase. AUC, peak, and duration displayed greater effects during the late phase than during the early phase. Baropressure of the early phase, but not of the late phase, significantly increased with increasing volume; however, small but significant viscosity effects on pressure were seen during both phases. Peak pressure of the late phase was preceded by maximum muscle activity, whereas that of the early phase was seen when muscle activity displayed a peak response. These findings indicated that our device with the ability to measure baropressure has the potential to provide additional parameter to assess the swallow physiology, and biphasic baropressure responses in the early and late phases could reflect functional aspects of the swallowing reflexes.

LORETA EEG phase reset of the default mode network.

PubMed

Thatcher, Robert W; North, Duane M; Biver, Carl J

2014-01-01

The purpose of this study was to explore phase reset of 3-dimensional current sources in Brodmann areas located in the human default mode network (DMN) using Low Resolution Electromagnetic Tomography (LORETA) of the human electroencephalogram (EEG). The EEG was recorded from 19 scalp locations from 70 healthy normal subjects ranging in age from 13 to 20 years. A time point by time point computation of LORETA current sources were computed for 14 Brodmann areas comprising the DMN in the delta frequency band. The Hilbert transform of the LORETA time series was used to compute the instantaneous phase differences between all pairs of Brodmann areas. Phase shift and lock durations were calculated based on the 1st and 2nd derivatives of the time series of phase differences. Phase shift duration exhibited three discrete modes at approximately: (1) 25 ms, (2) 50 ms, and (3) 65 ms. Phase lock duration present primarily at: (1) 300-350 ms and (2) 350-450 ms. Phase shift and lock durations were inversely related and exhibited an exponential change with distance between Brodmann areas. The results are explained by local neural packing density of network hubs and an exponential decrease in connections with distance from a hub. The results are consistent with a discrete temporal model of brain function where anatomical hubs behave like a "shutter" that opens and closes at specific durations as nodes of a network giving rise to temporarily phase locked clusters of neurons for specific durations.

Induction of L-phenylalanine ammonia-lyase during utilization of phenylalanine as a carbon or nitrogen source in Rhodotorula glutinis

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

Marusich, W.C.; Jensen, R.A.; Zamir, L.O.

Rhodotorula glutinis is a convenient source of L-phenylalanine ammonia-lyase, an enzyme that is useful as a biochemical reagent in the assay of L-phenylalanine. There have been previous descriptions of induced lyase production in complex medium where induction occurs late in exponential growth, suggesting a role in secondary metabolism such as is the case in higher plants. A higher specific activity of L-phenylalanine ammonia-lyase (sixfold higher than in complex medium) can be obtained during midexponential growth in a defined medium containing L-phenylalanine as the sole source of carbon. L-phenylalanine will also induce lyase synthesis during exponential growth in minimal medium inmore » which L-phenylalanine is the sole source of nitrogen. The appearance of lyase in complex medium supplemented with L-phenylalanine is probably triggered fortuitously by exhaustion late in growth of a prime source of nitrogen. In this study, R. glutinis appeared to express a single lyase enzyme, regardless of whether induction was nitrogen signaled or carbon signaled. Thin-layer chromatographic analysis of ether extracts prepared fom cultures induced with doubly labeled (U-/sup 14/C; ring-4-/sup 3/H) L-phenylalanine provided evidence of a catabolic sequence containing cinnamic acid, benzoic acid, and 4-hydroxybenzoic acid as degradative intermediates. 3,4-Dihydroxybenzoic acid was not identified as a catabolic intermediate.« less

Induction of L-phenylalanine ammonia-lyase during utilization of phenylalanine as a carbon or nitrogen source in Rhodotorula glutinis.

PubMed Central

Marusich, W C; Jensen, R A; Zamir, L O

1981-01-01

Rhodotorula glutinis is a convenient source of L-phenylalanine ammonia-lyase, an enzyme that is useful as a biochemical reagent in the assay of L-phenylalanine. There have been previous descriptions of induced lyase production in complex medium where induction occurs late in exponential growth, suggesting a role in secondary metabolism such as is the case in higher plants. A higher specific activity of L-phenylalanine ammonia-lyase (sixfold higher than a complex medium) can be obtained during midexponential growth in a defined medium containing L-phenylalanine as the sole source of carbon. L-Phenylalanine will also induce lyase synthesis during exponential growth in minimal in which L-phenylalanine is the sole source of nitrogen. The appearance of lyase in complex medium supplemented with L-phenylalanine is probably triggered fortuitously by exhaustion late in growth of a prime source of nitrogen. In this study, R. glutinis appeared to express a single lyase enzyme, regardless of whether induction was nitrogen signaled or carbon signaled. Thin-layer chromatographic analysis of ether extracts prepared from cultures induced with doubly labeled (U-14C; ring-4-3H) L-phenylalanine provided evidence of a catabolic sequence containing cinnamic acid, benzoic acid, and 4-hydroxybenzoic acid as degradative intermediates. 3,4-Dihydroxybenzoic acid was not identified as a catabolic intermediate. PMID:7195398

Long-Term Survival Phase Cells of Salmonella Typhimurium ATCC 14028 Have Significantly Greater Resistance to Ultraviolet Radiation in 0.85% Saline and Apple Juice.

PubMed

Wang, Fei; Mendonça, Aubrey; Brehm-Stecher, Byron F; Dickson, James; DiSpirito, Alan; Shaw, Angela; Thomas-Popo, Emalie

2018-05-31

Nonendospore-forming pathogenic bacteria in the long-term survival (LTS) phase can remain viable for months or years and may show reduced susceptibility to various antimicrobial interventions. In the present study, we investigated the response of LTS phase Salmonella enterica serovar Typhimurium (ATCC 14028) to ultraviolet (UV) radiation in 0.85% (w/v) saline and apple juice and the extent of sublethal injury in LTS phase survivors. The LTS-phase Salmonella Typhimurium cells were cultured at 35°C for 14 days in tryptic soy broth with 0.6% (w/v) yeast extract (TSBYE). Exponential- and stationary-phase cells, cultured in TSBYE (35°C) for 2.5 and 18 h, respectively, served as control samples. Cells (10 7 CFU [colony-forming unit]/mL) from each physiological state were exposed to UV light in saline (80 μW/cm 2 ) and apple juice (1500 μW/cm 2 ). The Salmonella Typhimurium survivors were plated for enumeration on either tryptic soy agar with 0.6% yeast extract or xylose-lysine-tergitol 4 (XLT4) agar and colonies counted after incubation (35°C, 24 h). Of all the growth phases tested, LTS phase cells were consistently impacted the least by UV treatment (p < 0.05). In saline, D-values of exponential, stationary, and LTS Salmonella Typhimurium were 0.35, 0.38, and 0.49 min, respectively. D-values in apple juice at pH 3.63 and pH 5.65 were 2.52, 3.19, and 3.57 min and 3.24, 3.50, and 4.18 min, respectively. UV radiation (80 μW/cm 2 ) of Salmonella Typhimurium in saline for 2.5 min reduced the number of exponential- and stationary-phase cells by ∼7.19 and 6.30 log 10 CFU/mL, respectively. In contrast, LTS cells were only reduced by 5.08 log 10 CFU/mL. Among the three physiological states, LTS phase cells had the least sublethal injury in the surviving population (p < 0.05). These results indicate that the LTS state cross-protects Salmonella Typhimurium against UV radiation and should be considered in determination of the UV radiation D-value for this pathogen.

On the late-time behavior of Virasoro blocks and a classification of semiclassical saddles

DOE PAGES

Fitzpatrick, A. Liam; Kaplan, Jared

2017-04-12

Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS 3/CFT 2 can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all ‘saddles’ that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, andmore » at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of a finite number of high-energy states cannot resolve a well-known version of the information loss problem in AdS 3. Furthermore, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.« less

On the late-time behavior of Virasoro blocks and a classification of semiclassical saddles

NASA Astrophysics Data System (ADS)

Fitzpatrick, A. Liam; Kaplan, Jared

2017-04-01

Recent work has demonstrated that black hole thermodynamics and information loss/restoration in AdS3/CFT2 can be derived almost entirely from the behavior of the Virasoro conformal blocks at large central charge, with relatively little dependence on the precise details of the CFT spectrum or OPE coefficients. Here, we elaborate on the non-perturbative behavior of Virasoro blocks by classifying all `saddles' that can contribute for arbitrary values of external and internal operator dimensions in the semiclassical large central charge limit. The leading saddles, which determine the naive semiclassical behavior of the Virasoro blocks, all decay exponentially at late times, and at a rate that is independent of internal operator dimensions. Consequently, the semiclassical contribution of a finite number of high-energy states cannot resolve a well-known version of the information loss problem in AdS3. However, we identify two infinite classes of sub-leading saddles, and one of these classes does not decay at late times.

Precipitation change and its effects on prehistorical human activities in the Gonghe Basin, Northeastern Qinghai-Tibet Plateau during middle and late Holocene

NASA Astrophysics Data System (ADS)

Hou, Xiaoqing; Hou, Guangliang; Wang, Fangfang; Wang, Qingbo

2018-02-01

Northeastern Qinghai-tibet Plateau is considered as the ideal region for study of the climate change during the Holocene. Based on the meteorological data, the surface & fossil pollen data, this paper reconstructed the precipitation series of the region since middle Holocene with the GIS and MAT techniques, and discussed its relationship with prehistorical human activities. The results indicate that there are four major climatic phases: (I) Middle Holocene Humid Phase (6300-5000 aBP), with the primitive millet-farming first imported into the region; (II) Late Middle Holocene Sub-humid Phase (5000-3900 aBP), with the millet-farming spread rapidly within the region; (III) Late Holocene Fluctuation Phase (3900-2900 aBP), with the mean annual precipitation dropped down to lower than 240 mm, and a production mode-shift to a combination of cropping and husbandry; (IV) Late Holocene Stationary Phase (2900-0 aBP), with a precipitation alike the modern time, and a steady farming-pastoral economic pattern.

Long-term mass transfer and mixing-controlled reactions of a DNAPL plume from persistent residuals

NASA Astrophysics Data System (ADS)

Liu, Yuan; Illangasekare, Tissa H.; Kitanidis, Peter K.

2014-02-01

Understanding and being able to predict the long-term behavior of DNAPL (i.e., PCE and TCE) residuals after active remediation has ceased have become increasingly important as attention at many sites turns from aggressive remediation to monitored natural attenuation and long-term stewardship. However, plume behavior due to mass loading and reactions during these later phases is less studied as they involve large spatial and temporal scales. We apply both theoretical analysis and pore-scale simulations to investigate mass transfer from DNAPL residuals and subsequent reactions within the generated plume, and, in particular, to show the differences between early- and late-time behaviors of the plume. In the zone of entry of the DNAPL entrapment zone where the concentration boundary layer in the flowing groundwater has not fully developed, the pore-scale simulations confirm the past findings based on laboratory studies that the mass transfer increases as a power-law function of the Peclét number, and is enhanced due to reactions in the plume. Away from the entry zone and further down gradient, the long-term reactions are limited by the available additive and mixing in the porous medium, thereby behave considerably differently from the entry zone. For the reaction between the contaminant and an additive with intrinsic second-order bimolecular kinetics, the late-time reaction demonstrates a first-order decay macroscopically with respect to the mass of the limiting additive, not with respect to that of the contaminant. The late-time decay rate only depends on the intrinsic reaction rate and the solubility of the entrapped DNAPL. At the intermediate time, the additive decays exponentially with the square of time (t2), instead of time (t). Moreover, the intermediate decay rate also depends on the initial conditions, the spatial distribution of DNAPL residuals, and the effective dispersion coefficient.

The mare reproductive loss syndrome and the eastern tent caterpillar: a toxicokinetic/statistical analysis with clinical, epidemiologic, and mechanistic implications.

PubMed

Sebastian, Manu; Gantz, Marie G; Tobin, Thomas; Harkins, J Daniel; Bosken, Jeffrey M; Hughes, Charlie; Harrison, Lenn R; Bernard, William V; Richter, Dana L; Fitzgerald, Terrence D

2003-01-01

During 2001, central Kentucky experienced acute transient epidemics of early and late fetal losses, pericarditis, and unilateral endophthalmitis, collectively referred to as mare reproductive loss syndrome (MRLS). A toxicokinetic/statistical analysis of experimental and field MRLS data was conducted using accelerated failure time (AFT) analysis of abortions following administration of Eastern tent caterpillars (ETCs; 100 or 50 g/day or 100 g of irradiated caterpillars/day) to late-term pregnant mares. In addition, 2001 late-term fetal loss field data were used in the analysis. Experimental data were fitted by AFT analysis at a high (P <.0001) significance. Times to first abortion ("lag time") and abortion rates were dose dependent. Lag times decreased and abortion rates increased exponentially with dose. Calculated dose x response data curves allow interpretation of abortion data in terms of "intubated ETC equivalents." Analysis suggested that field exposure to ETCs in 2001 in central Kentucky commenced on approximately April 27, was initially equivalent to approximately 5 g of intubated ETCs/day, and increased to approximately 30 g/day at the outbreak peak. This analysis accounts for many aspects of the epidemiology, clinical presentations, and manifestations of MRLS. It allows quantitative interpretation of experimental and field MRLS data and has implications for the basic mechanisms underlying MRLS. The results support suggestions that MRLS is caused by exposure to or ingestion of ETCs. The results also show that high levels of ETC exposure produce intense, focused outbreaks of MRLS, closely linked in time and place to dispersing ETCs, as occurred in central Kentucky in 2001. With less intense exposure, lag time is longer and abortions tend to spread out over time and may occur out of phase with ETC exposure, obscuring both diagnosis of this syndrome and the role of the caterpillars.

Carbon isotopic patterns of amino acids associated with various microbial metabolic pathways and physiological conditions

NASA Astrophysics Data System (ADS)

Wang, P. L.; Hsiao, K. T.; Lin, L. H.

2017-12-01

Amino acids represent one of the most important categories of biomolecule. Their abundance and isotopic patterns have been broadly used to address issues related to biochemical processes and elemental cycling in natural environments. Previous studies have shown that various carbon assimilative pathways of microorganisms (e.g. autotrophy, heterotrophy and acetotrophy) could be distinguished by carbon isotopic patterns of amino acids. However, the taxonomic and catabolic coverage are limited in previous examination. This study aims to uncover the carbon isotopic patterns of amino acids for microorganisms remaining uncharacterized but bearing biogeochemical and ecological significance in anoxic environments. To fulfill the purpose, two anaerobic strains were isolated from riverine wetland and mud volcano in Taiwan. One strain is a sulfate reducing bacterium (related to Desulfovibrio marrakechensis), which is capable of utilizing either H2 or lactate, and the other is a methanogen (related to Methanolobus profundi), which grows solely with methyl-group compounds. Carbon isotope analyses of amino acids were performed on cells grown in exponential and stationary phase. The isotopic patterns were similar for all examined cultures, showing successive 13C depletion along synthetic pathways. No significant difference was observed for the methanogen and lactate-utilizing sulfate reducer harvested in exponential and stationary phases. In contrast, the H2-utilizing sulfate reducer harvested in stationary phase depleted and enriched 13C in aspartic acid and glycine, respectively when compared with that harvested in exponential phase. Such variations might infer the change of carbon flux during synthesis of these two amino acids in the reverse TCA cycle. In addition, the discriminant function analysis for all available data from culture studies further attests the capability of using carbon isotope patterns of amino acids in identifying microbial metabolisms.

Unexpected features of exponentially growing Tobacco Bright Yellow-2 cell suspension culture in relation to excreted extracellular polysaccharides and cell wall composition.

PubMed

Issawi, Mohammad; Muhieddine, Mohammad; Girard, Celine; Sol, Vincent; Riou, Catherine

2017-10-01

This article presents a new insight about TBY-2 cells; from extracellular polysaccharides secretion to cell wall composition during cell suspension culture. In the medium of cells taken 2 days after dilution (end of lag phase), a two unit pH decrease from 5.38 to 3.45 was observed and linked to a high uronic acid (UA) amount secretion (47.8%) while, in 4 and 7 day-old spent media, pH increased and UA amounts decreased 35.6 and 42.3% UA, respectively. To attain deeper knowledge of the putative link between extracellular polysaccharide excretion and cell wall composition, we determined cell wall UA and neutral sugar composition of cells from D2 to D12 cultures. While cell walls from D2 and D3 cells contained a large amount of uronic acid (twice as much as the other analysed cell walls), similar amounts of neutral sugar were detected in cells from lag to end of exponential phase cells suggesting an enriched pectin network in young cultures. Indeed, monosaccharide composition analysis leads to an estimated percentage of pectins of 56% for D3 cell wall against 45% D7 cell walls indicating that the cells at the mid-exponential growth phase re-organized their cell wall linked to a decrease in secreted UA that finally led to a stabilization of the spent medium pH to 5.4. In conclusion, TBY-2 cell suspension from lag to stationary phase showed cell wall remodeling that could be of interest in drug interaction and internalization study.

The Oenococcus oeni clpX Homologue Is a Heat Shock Gene Preferentially Expressed in Exponential Growth Phase

PubMed Central

Jobin, Michel-Philippe; Garmyn, Dominique; Diviès, Charles; Guzzo, Jean

1999-01-01

Using degenerated primers from conserved regions of previously studied clpX gene products, we cloned the clpX gene of the malolactic bacterium Oenococcus oeni. The clpX gene was sequenced, and the deduced protein of 413 amino acids (predicted molecular mass of 45,650 Da) was highly similar to previously analyzed clpX gene products from other organisms. An open reading frame located upstream of the clpX gene was identified as the tig gene by similarity of its predicted product to other bacterial trigger factors. ClpX was purified by using a maltose binding protein fusion system and was shown to possess an ATPase activity. Northern analyses indicated the presence of two independent 1.6-kb monocistronic clpX and tig mRNAs and also showed an increase in clpX mRNA amount after a temperature shift from 30 to 42°C. The clpX transcript is abundant in the early exponential growth phase and progressively declines to undetectable levels in the stationary phase. Thus, unlike hsp18, the gene encoding one of the major small heat shock proteins of Oenococcus oeni, clpX expression is related to the exponential growth phase and requires de novo protein synthesis. Primer extension analysis identified the 5′ end of clpX mRNA which is located 408 nucleotides upstream of a putative AUA start codon. The putative transcription start site allowed identification of a predicted promoter sequence with a high similarity to the consensus sequence found in the housekeeping gene promoter of gram-positive bacteria as well as Escherichia coli. PMID:10542163

Vancomycin modifies the expression of the agr system in multidrug-resistant Staphylococcus aureus clinical isolates

PubMed Central

Cázares-Domínguez, Vicenta; Ochoa, Sara A.; Cruz-Córdova, Ariadnna; Rodea, Gerardo E.; Escalona, Gerardo; Olivares, Alma L.; Olivares-Trejo, José de Jesús; Velázquez-Guadarrama, Norma; Xicohtencatl-Cortes, Juan

2015-01-01

Staphylococcus aureus is an opportunistic pathogen that colonizes human hosts and causes a wide variety of diseases. Two interacting regulatory systems called agr (accessory gene regulator) and sar (staphylococcal accessory regulator) are involved in the regulation of virulence factors. The aim of this study was to evaluate the effect of vancomycin on hld and spa gene expression during the exponential and post-exponential growth phases in multidrug-resistant (MDR) S. aureus. Methods: Antibiotic susceptibility was evaluated by the standard microdilution method. The phylogenetic profile was obtained by pulsed-field gel electrophoresis (PFGE). Polymorphisms of agr and SCCmec (staphylococcal cassette chromosome mec) were analyzed by multiplex polymerase chain reaction (PCR). The expression levels of hld and spa were analyzed by reverse transcription-PCR. An enzyme-linked immunosorbent assay (ELISA) was performed to detect protein A, and biofilm formation was analyzed via crystal violet staining. Results: In total, 60.60% (20/33) of S. aureus clinical isolates were MDR. Half (10/20) of the MDR S. aureus isolates were distributed in subcluster 10, with >90% similarity among them. In the isolates of this subcluster, a high prevalence (100%) for the agrII and the cassette SCCmec II polymorphisms was found. Our data showed significant increases in hld expression during the post-exponential phase in the presence and absence of vancomycin. Significant increases in spa expression, protein A production and biofilm formation were observed during the post-exponential phase when the MDR S. aureus isolates were challenged with vancomycin. Conclusion: The polymorphism agrII, which is associated with nosocomial isolates, was the most prevalent polymorphism in MDR S. aureus. Additionally, under our study conditions, vancomycin modified hld and spa expression in these clinical isolates. Therefore, vancomycin may regulate alternative systems that jointly participate in the regulation of these virulence factors. PMID:25999924

Peptidoglycan Recycling in Gram-Positive Bacteria Is Crucial for Survival in Stationary Phase

PubMed Central

Borisova, Marina; Gaupp, Rosmarie; Duckworth, Amanda; Schneider, Alexander; Dalügge, Désirée; Mühleck, Maraike; Deubel, Denise; Unsleber, Sandra; Yu, Wenqi; Muth, Günther; Bischoff, Markus; Götz, Friedrich

2016-01-01

ABSTRACT Peptidoglycan recycling is a metabolic process by which Gram-negative bacteria reutilize up to half of their cell wall within one generation during vegetative growth. Whether peptidoglycan recycling also occurs in Gram-positive bacteria has so far remained unclear. We show here that three Gram-positive model organisms, Staphylococcus aureus, Bacillus subtilis, and Streptomyces coelicolor, all recycle the sugar N-acetylmuramic acid (MurNAc) of their peptidoglycan during growth in rich medium. They possess MurNAc-6-phosphate (MurNAc-6P) etherase (MurQ in E. coli) enzymes, which are responsible for the intracellular conversion of MurNAc-6P to N-acetylglucosamine-6-phosphate and d-lactate. By applying mass spectrometry, we observed accumulation of MurNAc-6P in MurNAc-6P etherase deletion mutants but not in either the isogenic parental strains or complemented strains, suggesting that MurQ orthologs are required for the recycling of cell wall-derived MurNAc in these bacteria. Quantification of MurNAc-6P in ΔmurQ cells of S. aureus and B. subtilis revealed small amounts during exponential growth phase (0.19 nmol and 0.03 nmol, respectively, per ml of cells at an optical density at 600 nm [OD600] of 1) but large amounts during transition (0.56 nmol and 0.52 nmol) and stationary (0.53 nmol and 1.36 nmol) phases. The addition of MurNAc to ΔmurQ cultures greatly increased the levels of intracellular MurNAc-6P in all growth phases. The ΔmurQ mutants of S. aureus and B. subtilis showed no growth deficiency in rich medium compared to the growth of the respective parental strains, but intriguingly, they had a severe survival disadvantage in late stationary phase. Thus, although peptidoglycan recycling is apparently not essential for the growth of Gram-positive bacteria, it provides a benefit for long-term survival. PMID:27729505

Life Stage-specific Proteomes of Legionella pneumophila Reveal a Highly Differential Abundance of Virulence-associated Dot/Icm effectors*

PubMed Central

Aurass, Philipp; Gerlach, Thomas; Becher, Dörte; Voigt, Birgit; Karste, Susanne; Bernhardt, Jörg; Riedel, Katharina; Hecker, Michael; Flieger, Antje

2016-01-01

Major differences in the transcriptional program underlying the phenotypic switch between exponential and post-exponential growth of Legionella pneumophila were formerly described characterizing important alterations in infection capacity. Additionally, a third state is known where the bacteria transform in a viable but nonculturable state under stress, such as starvation. We here describe phase-related proteomic changes in exponential phase (E), postexponential phase (PE) bacteria, and unculturable microcosms (UNC) containing viable but nonculturable state cells, and identify phase-specific proteins. We present data on different bacterial subproteomes of E and PE, such as soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins. In total, 1368 different proteins were identified, 922 were quantified and 397 showed differential abundance in E/PE. The quantified subproteomes of soluble whole cell proteins, outer membrane-associated proteins, and extracellular proteins; 841, 55, and 77 proteins, respectively, were visualized in Voronoi treemaps. 95 proteins were quantified exclusively in E, such as cell division proteins MreC, FtsN, FtsA, and ZipA; 33 exclusively in PE, such as motility-related proteins of flagellum biogenesis FlgE, FlgK, and FliA; and 9 exclusively in unculturable microcosms soluble whole cell proteins, such as hypothetical, as well as transport/binding-, and metabolism-related proteins. A high frequency of differentially abundant or phase-exclusive proteins was observed among the 91 quantified effectors of the major virulence-associated protein secretion system Dot/Icm (> 60%). 24 were E-exclusive, such as LepA/B, YlfA, MavG, Lpg2271, and 13 were PE-exclusive, such as RalF, VipD, Lem10. The growth phase-related specific abundance of a subset of Dot/Icm virulence effectors was confirmed by means of Western blotting. We therefore conclude that many effectors are predominantly abundant at either E or PE which suggests their phase specific function. The distinct temporal or spatial presence of such proteins might have important implications for functional assignments in the future or for use as life-stage specific markers for pathogen analysis. PMID:26545400

Evaluation of colour temperatures in the cultivation of Dunaliella salina and Nannochloropsis oculata in the production of lipids and carbohydrates.

PubMed

Pavón-Suriano, Salim Gabriel; Ortega-Clemente, Luis Alfredo; Curiel-Ramírez, Sergio; Jiménez-García, María Isabel; Pérez-Legaspi, Ignacio Alejandro; Robledo-Narváez, Paula Natalia

2017-07-25

The production of biofuels from microalgae is a promising and sustainable alternative. Its production is determined by the content of lipids and carbohydrates, which is different for each microalgae species and is affected by environmental factors, being lighting one of the principal determining their biochemical composition. The colour temperature (electromagnetic radiation and light spectrum) is a determining factor for the production of lipids and carbohydrates in microalgae. The aim of this assay was to evaluate the effect of three colour temperatures (6500, 10,000 and 20,000 °K) on the biomass (cel mL -1 ), biomass production and productivity (g L -1 and g L -1  day -1 ), lipid and carbohydrate content (%), lipid and carbohydrate production and productivity (mg L -1 and mg L -1  day -1 ), composition and content of fatty acids (%) in two microalgae species: Dunaliella salina and Nannochloropsis oculata. The highest cell density was observed for N. oculata in stationary phase in the control (83.93 × 106 cel mL -1 ). However, higher lipid content was obtained in D. salina in stationary phase at 10,000 °K (80%), while N. oculata showed 67% at 6500 °K. The highest carbohydrate content was 25% in stationary phase for D. salina at 20,000 °K. Regarding the production of lipids, D. salina reached a maximum of 523 mg L -1 in exponential phase at 6500 and 10,000 °K. The highest carbohydrate production was 38 mg L -1 for D. salina in exponential phase at 20,000 °K. In both microalgae, 15 different fatty acids were identified; the most abundant was palmitic acid with 35.8% for N. oculata in stationary phase at 10,000 °K, while D. salina showed 67% of polyunsaturated fatty acids in exponential phase at 6500 °K. In conclusion, the ideal colour temperature for microalgae culture to obtain biofuels should be based on the biomolecule of interest, being necessary to individually evaluate for each species.

Effect of ZCR-2060, an antiallergic agent, on antigen-induced immediate- and late-phase increases in airway resistance in sensitized guinea pigs.

PubMed

Abe, T; Yoshida, K; Omata, T; Segawa, Y; Matsuda, K; Nagai, H

1995-01-01

The effect of 2-[2-[4-(diphenylmethyl)-1-piperadinyl]ethoxy] benzoic acid maleate (ZCR-2060) on passive systemic anaphylaxis (PSA) and antigen-induced immediate- and late-phase increase in airway resistance (Rrs) in either passively or actively sensitized guinea pigs were investigated. ZCR-2060 inhibited PSA in guinea pigs. ID50 values of ZCR-2060, ketotifen, terfenadine and cetirizine on PSA were 0.03, 0.02, 0.8 and 0.3 mg/kg, respectively, when administered orally 1 h before the antigen challenge. The protective effect of ZCR-2060 was observed until 12 h before the antigen challenge. Aeroantigen-induce immediate increase in Rrs in passively sensitized guinea pigs with and without metyrapone treatment was inhibited by ZCR-2060, ketotifen, terfenadine and cetirizine. In contrast, prednisolone did not affect the aeroantigen-induced immediate increase in Rrs in animals not treated with metyrapone, but significantly inhibited the metyrapone-induced enhanced immediate response. In actively sensitized animals, the immediate- and late-phase increases in Rrs were observed within 30 min and between 3 and 8 h after the aeroantigen challenge. Pretreatment with metyrapone accelerated both antigen-induced responses. ZCR-2060 (1 mg/kg) significantly inhibited both responses. Ketotifen (1 mg/kg), terfenadine (10 mg/kg) and prednisolone (10 mg/kg) significantly the inhibited the late-phase response, but did not affect the immediate-phase response. In contrast, Cetirizine (10 mg/kg) did not affect either response. The effect of ZCR-2060 on late-phase response was stronger than that of ketotifen, terfenadine and cetirizine, and was almost the same as that of prednisolone. These results suggest that ZCR-2060 has a potent protective effect on immediate- and late-phase increases in Rrs.

Very slow growth of Escherichia coli.

PubMed Central

Chesbro, W; Evans, T; Eifert, R

1979-01-01

A recycling fermentor (a chemostat with 100% biomass feedback) was used to study glucose-limited behavior of Escherichia coli B. The expectation from mass transfer analysis that growth would asymptotically approach a limit mass determined by the glucose provision rate (GPR) and the culture's maintenance requirement was not met. Instead, growth proceeded at progressively lower rates through three distinct phases. After the fermentor was seeded, but before glucose became limiting, growth followed the usual, exponential path (phase 1). About 12 h postseeding, residual glucose in the fermentor fell below 1 microgram . ml-1 and the growth rate (dx/dt) became constant and a linear function of GPR (phase 2). The specific growth rate, mu, therefore fell continuously throughout the phase. Biomass yield and glucose assimilation (13%) were near the level for exponential growth, however, and independent of GPR over a broad range. At a critical specific growth rate (0.04 h-1 for this strain), phase 2 ended abruptly and phase 3 commenced. In phase 3, the growth rate was again constant, although lower than in phase 2, so that mu continued to fall, but growth rates and yields were praboloid functions of GPR. They were never zero, however, at any positive value of GPR. By inference, the fraction of metabolic energy used for maintenance functions is constant for a given GPR, although different for phases 2 and 3, and independent of biomass. In both phases 2 and 3, orcinol, diphenylamine, and Lowry reactive materials were secreted at near-constant rates such that over 50% as much biosynthetic mass was secreted as was retained by the cells. Images PMID:378981

Domain wall formation in late-time phase transitions

NASA Technical Reports Server (NTRS)

Kolb, Edward W.; Wang, Yun

1992-01-01

We examine domain wall formulation in late time phase transitions. We find that in the invisible axion domain wall phenomenon, thermal effects alone are insufficient to drive different parts of the disconnected vacuum manifold. This suggests that domain walls do not form unless either there is some supplemental (but perhaps not unreasonable) dynamics to localize the scalar field responsible for the phase transition to the low temperature maximum (to an extraordinary precision) before the onset of the phase transition, or there is some non-thermal mechanism to produce large fluctuations in the scalar field. The fact that domain wall production is not a robust prediction of late time transitions may suggest future directions in model building.

Free drainage of aqueous foams: Container shape effects on capillarity and vertical gradients

NASA Astrophysics Data System (ADS)

Saint-Jalmes, A.; Vera, M. U.; Durian, D. J.

2000-06-01

The standard drainage equation applies only to foam columns of constant cross-sectional area. Here, we generalize to include the effects of arbitrary container shape and develop an exact solution for an exponential, "Eiffel Tower", sample. This geometry largely eliminates vertical wetness gradients, and hence capillary effects, and should permit a clean test of dissipation mechanisms. Agreement with experiment is not achieved at late times, however, highlighting the importance of both boundary conditions and coarsening.

Non-exponential decoherence of radio-frequency resonance rotation of spin in storage rings

NASA Astrophysics Data System (ADS)

Saleev, A.; Nikolaev, N. N.; Rathmann, F.; Hinder, F.; Pretz, J.; Rosenthal, M.

2017-08-01

Precision experiments, such as the search for electric dipole moments of charged particles using radio-frequency spin rotators in storage rings, demand for maintaining the exact spin resonance condition for several thousand seconds. Synchrotron oscillations in the stored beam modulate the spin tune of off-central particles, moving it off the perfect resonance condition set for central particles on the reference orbit. Here, we report an analytic description of how synchrotron oscillations lead to non-exponential decoherence of the radio-frequency resonance driven up-down spin rotations. This non-exponential decoherence is shown to be accompanied by a nontrivial walk of the spin phase. We also comment on sensitivity of the decoherence rate to the harmonics of the radio-frequency spin rotator and a possibility to check predictions of decoherence-free magic energies.

Evaluation of normalization reference genes for RT-qPCR analysis of spo0A and four sporulation sigma factor genes in Clostridium botulinum Group I strain ATCC 3502.

PubMed

Kirk, David G; Palonen, Eveliina; Korkeala, Hannu; Lindström, Miia

2014-04-01

Heat-resistant spores of Clostridium botulinum can withstand the pasteurization processes in modern food processing. This poses a risk to food safety as spores may germinate into botulinum neurotoxin-producing vegetative cells. Sporulation in Bacillus subtilis, the model organism for sporulation, is regulated by the transcription factor Spo0A and four alternative sigma factors, SigF, SigE, SigG, and SigK. While the corresponding regulators are found in available genomes of C. botulinum, little is known about their expression. To accurately measure the expression of these genes using quantitative reverse-transcriptase PCR (RT-qPCR) during the exponential and stationary growth phases, a suitable normalization reference gene is required. 16S rrn, adK, alaS, era, gluD, gyrA, rpoC, and rpsJ were selected as the candidate reference genes. The most stable candidate reference gene was 16S ribosomal RNA gene (rrn), based on its low coefficient of variation (1.81%) measured during the 18-h study time. Using 16S rrn as the normalization reference gene, the relative expression levels of spo0A, sigF, sigE, sigG, and sigK were measured over 18h. The pattern of expression showed spo0A expression during the logarithmic growth phase, followed by a drop in expression upon entry to the stationary phase. Expression levels of sigF, sigE, and sigG peaked simultaneously at the end of the exponential growth phase. Peak expression of sigK occurred at 18h, however low levels of expression were detected during the exponential phase. These findings suggest these sigma factors play a role in C. botulinum sporulation that is similar, but not equal, to their role in the B. subtilis model. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modelling the interactions between Pseudomonas putida and Escherichia coli O157:H7 in fish-burgers: use of the lag-exponential model and of a combined interaction index.

PubMed

Speranza, B; Bevilacqua, A; Mastromatteo, M; Sinigaglia, M; Corbo, M R

2010-08-01

The objective of the current study was to examine the interactions between Pseudomonas putida and Escherichia coli O157:H7 in coculture studies on fish-burgers packed in air and under different modified atmospheres (30 : 40 : 30 O(2) : CO(2) : N(2), 5 : 95 O(2) : CO(2) and 50 : 50 O(2) : CO(2)), throughout the storage at 8 degrees C. The lag-exponential model was applied to describe the microbial growth. To give a quantitative measure of the occurring microbial interactions, two simple parameters were developed: the combined interaction index (CII) and the partial interaction index (PII). Under air, the interaction was significant (P < 0.05) only within the exponential growth phase (CII, 1.72), whereas under the modified atmospheres, the interactions were highly significant (P < 0.001) and occurred both in the exponential and in the stationary phase (CII ranged from 0.33 to 1.18). PII values for E. coli O157:H7 were lower than those calculated for Ps. putida. The interactions occurring into the system affected both E. coli O157:H7 and pseudomonads subpopulations. The packaging atmosphere resulted in a key element. The article provides some useful information on the interactions occurring between E. coli O157:H7 and Ps. putida on fish-burgers. The proposed index describes successfully the competitive growth of both micro-organisms, giving also a quantitative measure of a qualitative phenomenon.

The agr Locus Regulates Virulence and Colonization Genes in Clostridium difficile 027

PubMed Central

Martin, Melissa J.; Clare, Simon; Goulding, David; Faulds-Pain, Alexandra; Barquist, Lars; Browne, Hilary P.; Pettit, Laura; Dougan, Gordon; Lawley, Trevor D.

2013-01-01

The transcriptional regulator AgrA, a member of the LytTR family of proteins, plays a key role in controlling gene expression in some Gram-positive pathogens, including Staphylococcus aureus and Enterococcus faecalis. AgrA is encoded by the agrACDB global regulatory locus, and orthologues are found within the genome of most Clostridium difficile isolates, including the epidemic lineage 027/BI/NAP1. Comparative RNA sequencing of the wild type and otherwise isogenic agrA null mutant derivatives of C. difficile R20291 revealed a network of approximately 75 differentially regulated transcripts at late exponential growth phase, including many genes associated with flagellar assembly and function, such as the major structural subunit, FliC. Other differentially regulated genes include several involved in bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP) synthesis and toxin A expression. C. difficile 027 R20291 agrA mutant derivatives were poorly flagellated and exhibited reduced levels of colonization and relapses in the murine infection model. Thus, the agr locus likely plays a contributory role in the fitness and virulence potential of C. difficile strains in the 027/BI/NAP1 lineage. PMID:23772065

Laser acceleration

NASA Astrophysics Data System (ADS)

Tajima, T.; Nakajima, K.; Mourou, G.

2017-02-01

The fundamental idea of Laser Wakefield Acceleration (LWFA) is reviewed. An ultrafast intense laser pulse drives coherent wakefield with a relativistic amplitude robustly supported by the plasma. While the large amplitude of wakefields involves collective resonant oscillations of the eigenmode of the entire plasma electrons, the wake phase velocity ˜ c and ultrafastness of the laser pulse introduce the wake stability and rigidity. A large number of worldwide experiments show a rapid progress of this concept realization toward both the high-energy accelerator prospect and broad applications. The strong interest in this has been spurring and stimulating novel laser technologies, including the Chirped Pulse Amplification, the Thin Film Compression, the Coherent Amplification Network, and the Relativistic Mirror Compression. These in turn have created a conglomerate of novel science and technology with LWFA to form a new genre of high field science with many parameters of merit in this field increasing exponentially lately. This science has triggered a number of worldwide research centers and initiatives. Associated physics of ion acceleration, X-ray generation, and astrophysical processes of ultrahigh energy cosmic rays are reviewed. Applications such as X-ray free electron laser, cancer therapy, and radioisotope production etc. are considered. A new avenue of LWFA using nanomaterials is also emerging.

Production of acyl-homoserine lactone quorum-sensing signals is widespread in gram-negative Methylobacterium.

PubMed

Poonguzhali, Selvaraj; Madhaiyan, Munusamy; Sa, Tongmin

2007-02-01

Members of Methylobacterium, referred as pink-pigmented facultative methylotrophic bacteria, are frequently associated with terrestrial and aquatic plants, tending to form aggregates on the phyllosphere. We report here that the production of autoinducer molecules involved in the cell-to-cell signaling process, which is known as quorum sensing, is common among Methylobacterium species. Several strains of Methylobacterium were tested for their ability to produce N-acyl-homoserine lactone (AHL) signal molecules using different indicators. Most strains of Methylobacterium tested could elicit a positive response in Agrobacterium tumefaciens harboring lacZ fused to a gene that is regulated by autoinduction. The synthesis of these compounds was cell-density dependent, and the maximal activity was reached during the late exponential to stationary phases. The bacterial extracts were separated by thin-layer chromatography and bioassayed with A. tumefaciens NT1 (traR, tra::lacZ749). They revealed the production of various patterns of the signal molecules, which are strain dependent. At least two signal molecules could be detected in most of the strains tested, and comparison of their relative mobilities suggested that they are homologs of N-octanoyl-DL-homoserine lactone (C8-HSL) and N-decanoyl-DL-homoserine lactone (C10-HSL).

Physical and numerical sources of computational inefficiency in integration of chemical kinetic rate equations: Etiology, treatment and prognosis

NASA Technical Reports Server (NTRS)

Pratt, D. T.; Radhakrishnan, K.

1986-01-01

The design of a very fast, automatic black-box code for homogeneous, gas-phase chemical kinetics problems requires an understanding of the physical and numerical sources of computational inefficiency. Some major sources reviewed in this report are stiffness of the governing ordinary differential equations (ODE's) and its detection, choice of appropriate method (i.e., integration algorithm plus step-size control strategy), nonphysical initial conditions, and too frequent evaluation of thermochemical and kinetic properties. Specific techniques are recommended (and some advised against) for improving or overcoming the identified problem areas. It is argued that, because reactive species increase exponentially with time during induction, and all species exhibit asymptotic, exponential decay with time during equilibration, exponential-fitted integration algorithms are inherently more accurate for kinetics modeling than classical, polynomial-interpolant methods for the same computational work. But current codes using the exponential-fitted method lack the sophisticated stepsize-control logic of existing black-box ODE solver codes, such as EPISODE and LSODE. The ultimate chemical kinetics code does not exist yet, but the general characteristics of such a code are becoming apparent.

Fast and Accurate Fitting and Filtering of Noisy Exponentials in Legendre Space

PubMed Central

Bao, Guobin; Schild, Detlev

2014-01-01

The parameters of experimentally obtained exponentials are usually found by least-squares fitting methods. Essentially, this is done by minimizing the mean squares sum of the differences between the data, most often a function of time, and a parameter-defined model function. Here we delineate a novel method where the noisy data are represented and analyzed in the space of Legendre polynomials. This is advantageous in several respects. First, parameter retrieval in the Legendre domain is typically two orders of magnitude faster than direct fitting in the time domain. Second, data fitting in a low-dimensional Legendre space yields estimates for amplitudes and time constants which are, on the average, more precise compared to least-squares-fitting with equal weights in the time domain. Third, the Legendre analysis of two exponentials gives satisfactory estimates in parameter ranges where least-squares-fitting in the time domain typically fails. Finally, filtering exponentials in the domain of Legendre polynomials leads to marked noise removal without the phase shift characteristic for conventional lowpass filters. PMID:24603904

LORETA EEG phase reset of the default mode network

PubMed Central

Thatcher, Robert W.; North, Duane M.; Biver, Carl J.

2014-01-01

Objectives: The purpose of this study was to explore phase reset of 3-dimensional current sources in Brodmann areas located in the human default mode network (DMN) using Low Resolution Electromagnetic Tomography (LORETA) of the human electroencephalogram (EEG). Methods: The EEG was recorded from 19 scalp locations from 70 healthy normal subjects ranging in age from 13 to 20 years. A time point by time point computation of LORETA current sources were computed for 14 Brodmann areas comprising the DMN in the delta frequency band. The Hilbert transform of the LORETA time series was used to compute the instantaneous phase differences between all pairs of Brodmann areas. Phase shift and lock durations were calculated based on the 1st and 2nd derivatives of the time series of phase differences. Results: Phase shift duration exhibited three discrete modes at approximately: (1) 25 ms, (2) 50 ms, and (3) 65 ms. Phase lock duration present primarily at: (1) 300–350 ms and (2) 350–450 ms. Phase shift and lock durations were inversely related and exhibited an exponential change with distance between Brodmann areas. Conclusions: The results are explained by local neural packing density of network hubs and an exponential decrease in connections with distance from a hub. The results are consistent with a discrete temporal model of brain function where anatomical hubs behave like a “shutter” that opens and closes at specific durations as nodes of a network giving rise to temporarily phase locked clusters of neurons for specific durations. PMID:25100976

Characterization, production, and purification of leucocin H, a two-peptide bacteriocin from Leuconostoc MF215B.

PubMed

Blom, H; Katla, T; Holck, A; Sletten, K; Axelsson, L; Holo, H

1999-07-01

Leuconostoc MF215B was found to produce a two-peptide bacteriocin referred to as leucocin H. The two peptides were termed leucocin Halpha and leucocin Hbeta. When acting together, they inhibit, among others, Listeria monocytogenes, Bacillus cereus, and Clostridium perfringens. Production of leucocin H in growth medium takes place at temperatures down to 6 degrees C and at pH below 7. The highest activity of leucocin H in growth medium was demonstrated in the late exponential growth phase. The bacteriocin was purified by precipitation with ammonium sulfate, ion-exchange (SP Sepharose) and reverse phase chromatography. Upon purification, specific activity increased 10(5)-fold, and the final specific activity was 2 x 10(7) BU/OD280. Amino acid composition analyses of leucocin Halpha and leucocin Hbeta indicated that both peptides consisted of around 40 amino acid residues. Their N-termini were blocked for Edman degradation, and the methionin residues of leucocin Hbeta did not respond to Cyanogen Bromide (CNBr) cleavage. Absorbance at 280 nm indicated the presence of tryptophan residues and tryptophan-fracturing opened for partial sequencing by Edman degradation. From leucocin Halpha, the sequence of 20 amino acids was obtained; from leucocin Hbeta the sequence of 28 amino acid residues was obtained. No sequence homology to other known bacteriocins could be demonstrated. It also appeared that the two peptides themselves shared little or no sequence homology. The presence of soy oil did not affect the activity of leucocin H in agar.

Identification and validation of sRNAs in Edwardsiella tarda S08.

PubMed

Sun, Yuying; Zhang, Jiquan; Qin, Lei; Yan, Cui; Zhang, Xiaojun; Liu, Dandan

2017-01-01

Bacterial small non-coding RNAs (sRNAs) are known as novel regulators involved in virulence, stress responsibility, and so on. Recently, a lot of new researches have highlighted the critical roles of sRNAs in fine-tune gene regulation in both prokaryotes and eukaryotes. Edwardsiella tarda (E. tarda) is a gram-negative, intracellular pathogen that causes edwardsiellosis in fish. Thus far, no sRNA has been reported in E. tarda. The present study represents the first attempt to identify sRNAs in E. tarda S08. Ten sRNAs were validated by RNA sequencing and quantitative PCR (qPCR). ET_sRNA_1 and ET_sRNA_2 were homolous to tmRNA and GcvB, respectively. However, the other candidate sRNAs have not been reported till now. The cellular abundance of 10 validated sRNA was detected by qPCR at different growth phases to monitor their biosynthesis. Nine candidate sRNAs were expressed in the late-stage of exponential growth and stationary stages of growth (36~60 h). And the expression of the nine sRNAs was growth phase-dependent. But ET_sRNA_10 was almost expressed all the time and reached the highest peak at 48 h. Their targets were predicted by TargetRNA2 and each sRNA target contains some genes that directly or indirectly relate to virulence. These results preliminary showed that sRNAs probably play a regulatory role of virulence in E. tarda.

Multiple determinants controlling activation of yeast replication origins late in S phase.

PubMed

Friedman, K L; Diller, J D; Ferguson, B M; Nyland, S V; Brewer, B J; Fangman, W L

1996-07-01

Analysis of a 131-kb segment of the left arm of yeast chromosome XIV beginning 157 kb from the telomere reveals four highly active origins of replication that initiate replication late in S phase. Previous work has shown that telomeres act as determinants for late origin activation. However, at least two of the chromosome XIV origins maintain their late activation time when located on large circular plasmids, indicating that late replication is independent of telomeres. Analysis of the replication time of plasmid derivatives containing varying amounts of chromosome XIV DNA show that a minimum of three chromosomal elements, distinct from each tested origin, contribute to late activation time. These late determinants are functionally equivalent, because duplication of one set of contributing sequences can compensate for the removal of another set. Furthermore, insertion of an origin that is normally early activated into this domain results in a shift to late activation, suggesting that the chromosome XIV origins are not unique in their ability to respond to the late determinants.

Rapid assessment of Oenococcus oeni activity by measuring intracellular pH and membrane potential by flow cytometry, and its application to the more effective control of malolactic fermentation.

PubMed

Bouix, M; Ghorbal, S

2015-01-16

The aim of this study is to highlight the changes in the physiological cellular state of Oenococcus oeni during malolactic fermentation (MLF), and to use its cellular parameters to improve existing knowledge of O. oeni behaviour and to more effectively control the performance of the bacteria during MLF in wine. To do this, measurements of intracellular pH, transmembrane potential and vitality were performed using flow cytometry with different fluorescent probes: CFDA-SE and CDCF, DiBAC and CFDA, respectively. The kinetics of the cellular changes in these parameters were determined during MLF in FT80 synthetic medium and in white wine, as were the kinetics of malic acid consumption. pHin measurement throughout the entire growth shows that the pH was equal to the pH of the culture medium during the early stage, increased to pH6 in the exponential phase, and then decreased to equilibrate with the pH of the medium in the late stationary phase. Membrane potential increased in early MLF and then decreased. The decrease in pHin and membrane potential occurred when all of the malic acid was consumed. Finally, we showed that the higher the ΔpH (pHin-pHex) in O. oeni cells was, the shorter the lag phase of the MLF was. To better manage the initiation of MLF in wines, the physiological state of O. oeni cells must be taken into account. These results allow us to understand the sometimes random initiation of MLF in wines inoculated with O. oeni and to suggest ways to improve this control. Copyright © 2014 Elsevier B.V. All rights reserved.

Gene expression at each stage of the life cycle of spore-forming bacteria: different sensitivity of transcription to antibiotics which act on DNA gyrase.

PubMed

Matsuda, M; Kameyama, T

1985-01-01

Effects of antibiotics acting on DNA gyrase, novobiocin and nalidixic acid on RNA synthesis during germination, vegetative growth and sporulation of Bacillus subtilis were examined. These drugs were relatively ineffective in inhibiting RNA synthesis of phase Gm 1 (5-15 min) during germination but effective in those of Gm 2 (15-40 min) and Gm 3 (40-60 min) during germination (Matsuda and Kameyama 1980). No distinguishable inhibitory effects of RNA synthesis in B. subtilis NOVr1TT mutant could be detected by novobiocin. RNA synthesis of Gm 2 and Gm 3 of this mutant was inhibited by nalidixic acid. When novobiocin was added to exponential vegetative cell or sporulating cell culture at T0 and T1 stage, the rate of RNA synthesis was inhibited by 80% for 5 min following addition of the drug. However, RNA synthesis after T2 of sporulation became resistant toward novobiocin, as was the case at an early stage of germination. RNA profiles from transcripts synthesized on administration of NOV suggested that the suppression of the synthesis of 23S and 16S rRNA is relatively greater than 4 to 5S RNA at the middle stage of germination and at vegetative growth stage in the presence of NOV. Our present data suggest that DNA gyrase is involved in the regulation of gene transcription during middle and late phases of germination, vegetative growth and T0 and T1 of sporulation. The transcription during early phase of germination and sporulation after T2 may proceed independently of this enzyme.

Early Changes in the Ultrastructure of Streptococcus faecalis After Amino Acid Starvation

PubMed Central

Higgins, M. L.; Shockman, G. D.

1970-01-01

Thin sections of Streptococcus faecalis (ATCC 9790) starved of one essential amino acid (threonine or valine) initially show rapid increases in (i) cell wall thickness, (ii) the apparent size of the central nucleoid region, and (iii) mesosomal membranes. The most rapid increases in all three variables occurred during the first 1 to 2 hr of starvation. After this initial period, the rates progressively decreased over the 20-hr observation period. During threonine starvation, the mesosomal membrane that accumulated in the first hour was subsequently degraded and reached a level similar to that found in exponential-phase cells after 20 hr. With valine starvation, mesosomal membrane continued to slowly accumulate over the entire 20-hr observation period. The mesosomes of the starved cells retained the same “stalked-bag” morphology of those in exponential-phase cells. These cytological observations agree with previously published biochemical data on membrane lipid and wall content after starvation. Images PMID:4987306

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2017-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and [Formula: see text] robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

Decentralized Feedback Controllers for Robust Stabilization of Periodic Orbits of Hybrid Systems: Application to Bipedal Walking

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially and robustly stabilize periodic orbits for hybrid dynamical systems against possible uncertainties in discrete-time phases. The algorithm assumes a family of parameterized and decentralized nonlinear controllers to coordinate interconnected hybrid subsystems based on a common phasing variable. The exponential and H2 robust stabilization problems of periodic orbits are translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities. By investigating the properties of the Poincaré map, some sufficient conditions for the convergence of the iterative algorithm are presented. The power of the algorithm is finally demonstrated through designing a set of robust stabilizing local nonlinear controllers for walking of an underactuated 3D autonomous bipedal robot with 9 degrees of freedom, impact model uncertainties, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:28959117

Diffusive processes in a stochastic magnetic field

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

Wang, H.; Vlad, M.; Vanden Eijnden, E.

1995-05-01

The statistical representation of a fluctuating (stochastic) magnetic field configuration is studied in detail. The Eulerian correlation functions of the magnetic field are determined, taking into account all geometrical constraints: these objects form a nondiagonal matrix. The Lagrangian correlations, within the reasonable Corrsin approximation, are reduced to a single scalar function, determined by an integral equation. The mean square perpendicular deviation of a geometrical point moving along a perturbed field line is determined by a nonlinear second-order differential equation. The separation of neighboring field lines in a stochastic magnetic field is studied. We find exponentiation lengths of both signs describing,more » in particular, a decay (on the average) of any initial anisotropy. The vanishing sum of these exponentiation lengths ensures the existence of an invariant which was overlooked in previous works. Next, the separation of a particle`s trajectory from the magnetic field line to which it was initially attached is studied by a similar method. Here too an initial phase of exponential separation appears. Assuming the existence of a final diffusive phase, anomalous diffusion coefficients are found for both weakly and strongly collisional limits. The latter is identical to the well known Rechester-Rosenbluth coefficient, which is obtained here by a more quantitative (though not entirely deductive) treatment than in earlier works.« less

μ SR studies of the extended kagome systems YBaCo4O7+δ (δ = 0 and 0.1)

NASA Astrophysics Data System (ADS)

Lee, Suheon; Lee, Wonjun; Mitchell, John; Choi, Kwang-Yong

We present a μSR study of the extended kagome systems YBaCo4O7+δ (δ = 0 and 0.1), which are made up of an alternating stacking of triangular and kagome layers. The parent material YBaCo4O7.0 undergoes a structural phase transition at 310 K, releasing geometrical frustration and thereby stabilizing an antiferromagnetically ordered state below TN = 106 K. The μSR spectra of YBaCo4O7.0 exhibit the loss of initial asymmetry and the development of a fast relaxation component below TN = 111 K. This indicates that the Co spins in the kagome planes remain in an inhomogeneous and dynamically fluctuating state down to 4 K, while the triangular spins order antiferromagnetically below TN. The nonstoichiometric YBaCo4O7.1 compound with no magnetic ordering exhibits a disparate spin dynamics between the fast cooling (10 K/min) and slow cooling (1 K/min) procedures. While the fast-cooled μSR spectra show a simple exponential decay, the slow-cooled spectra are described with a sum of a simple exponential function and a stretched exponential function. These are in agreements with the occurrence of the phase separation between interstitial oxygen-rich and poor regions in the slow-cooling measurements.

Partitioning of monomethylmercury between freshwater algae and water.

PubMed

Miles, C J; Moye, H A; Phlips, E J; Sargent, B

2001-11-01

Phytoplankton-water monomethylmercury (MeHg) partition constants (KpI) have been determined in the laboratory for two green algae Selenastrum capricornutum and Cosmarium botrytis, the blue-green algae Schizothrix calcicola, and the diatom Thallasiosira spp., algal species that are commonly found in natural surface waters. Two methods were used to determine KpI, the Freundlich isotherm method and the flow-through/dialysis bag method. Both methods yielded KpI values of about 10(6.6) for S. capricornutum and were not significantly different. The KpI for the four algae studied were similar except for Schizothrix, which was significantly lower than S. capricornutum. The KpI for MeHg and S. capricornutum (exponential growth) was not significantly different in systems with predominantly MeHgOH or MeHgCl species. This is consistent with other studies that show metal speciation controls uptake kinetics, but the reactivity with intracellular components controls steady-state concentrations. Partitioning constants determined with exponential and stationary phase S. capricornutum cells at the same conditions were not significantly different, while the partitioning constant for exponential phase, phosphorus-limited cells was significantly lower, suggesting that P-limitation alters the ecophysiology of S. capricornutum sufficiently to impact partitioning, which may then ultimately affect mercury levels in higher trophic species.

Clinical proteomics in kidney disease as an exponential technology: heading towards the disruptive phase.

PubMed

Sanchez-Niño, Maria Dolores; Sanz, Ana B; Ramos, Adrian M; Fernandez-Fernandez, Beatriz; Ortiz, Alberto

2017-04-01

Exponential technologies double in power or processing speed every year, whereas their cost halves. Deception and disruption are two key stages in the development of exponential technologies. Deception occurs when, after initial introduction, technologies are dismissed as irrelevant, while they continue to progress, perhaps not as fast or with so many immediate practical applications as initially thought. Twenty years after the first publications, clinical proteomics is still not available in most hospitals and some clinicians have felt deception at unfulfilled promises. However, there are indications that clinical proteomics may be entering the disruptive phase, where, once refined, technologies disrupt established industries or procedures. In this regard, recent manuscripts in CKJ illustrate how proteomics is entering the clinical realm, with applications ranging from the identification of amyloid proteins in the pathology lab, to a new generation of urinary biomarkers for chronic kidney disease (CKD) assessment and outcome prediction. Indeed, one such panel of urinary peptidomics biomarkers, CKD273, recently received a Food and Drug Administration letter of support, the first ever in the CKD field. In addition, a must-read resource providing information on kidney disease-related proteomics and systems biology databases and how to access and use them in clinical decision-making was also recently published in CKJ .

Identification of Metabolic Pathways Expressed by Pichia anomala Kh6 in the Presence of the Pathogen Botrytis cinerea on Apple: New Possible Targets for Biocontrol Improvement

PubMed Central

Kwasiborski, Anthony; Bajji, Mohammed; Renaut, Jenny; Delaplace, Pierre; Jijakli, M. Haissam

2014-01-01

Yeast Pichia anomala strain Kh6 Kurtzman (Saccharomycetales: Endomycetaceae) exhibits biological control properties that provide an alternative to the chemical fungicides currently used by fruit or vegetable producers against main post-harvest pathogens, such as Botrytis cinerea (Helotiales: Sclerotiniaceae). Using an in situ model that takes into account interactions between organisms and a proteomic approach, we aimed to identify P. anomala metabolic pathways influenced by the presence of B. cinerea. A total of 105 and 60 P. anomala proteins were differentially represented in the exponential and stationary growth phases, respectively. In the exponential phase and in the presence of B. cinerea, the pentose phosphate pathway seems to be enhanced and would provide P. anomala with the needed nucleic acids and energy for the wound colonisation. In the stationary phase, P. anomala would use alcoholic fermentation both in the absence and presence of the pathogen. These results would suggest that the competitive colonisation of apple wounds could be implicated in the mode of action of P. anomala against B. cinerea. PMID:24614090

Transcription closed and open complex dynamics studies reveal balance between genetic determinants and co-factors

NASA Astrophysics Data System (ADS)

Sala, Adrien; Shoaib, Muhammad; Anufrieva, Olga; Mutharasu, Gnanavel; Jahan Hoque, Rawnak; Yli-Harja, Olli; Kandhavelu, Meenakshisundaram

2015-05-01

In E. coli, promoter closed and open complexes are key steps in transcription initiation, where magnesium-dependent RNA polymerase catalyzes RNA synthesis. However, the exact mechanism of initiation remains to be fully elucidated. Here, using single mRNA detection and dual reporter studies, we show that increased intracellular magnesium concentration affects Plac initiation complex formation resulting in a highly dynamic process over the cell growth phases. Mg2+ regulates transcription transition, which modulates bimodality of mRNA distribution in the exponential phase. We reveal that Mg2+ regulates the size and frequency of the mRNA burst by changing the open complex duration. Moreover, increasing magnesium concentration leads to higher intrinsic and extrinsic noise in the exponential phase. RNAP-Mg2+ interaction simulation reveals critical movements creating a shorter contact distance between aspartic acid residues and Nucleotide Triphosphate residues and increasing electrostatic charges in the active site. Our findings provide unique biophysical insights into the balanced mechanism of genetic determinants and magnesium ion in transcription initiation regulation during cell growth.

Late time behaviors of an inhomogeneous rolling tachyon

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

Kwon, O-Kab; Lee, Chong Oh; Basic Science Research Institute, Chonbuk National University, Chonju 561-756

2006-06-15

We study an inhomogeneous decay of an unstable D-brane in the context of Dirac-Born-Infeld (DBI)-type effective action. We consider tachyon and electromagnetic fields with dependence of time and one spatial coordinate, and an exact solution is found under an exponentially decreasing tachyon potential, e{sup -|T|/{radical}}{sup (2)}, which is valid for the description of the late time behavior of an unstable D-brane. Though the obtained solution contains both time and spatial dependence, the corresponding momentum density vanishes over the entire spacetime region. The solution is governed by two parameters. One adjusts the distribution of energy density in the inhomogeneous direction, andmore » the other interpolates between the homogeneous rolling tachyon and static configuration. As time evolves, the energy of the unstable D-brane is converted into the electric flux and tachyon matter.« less

RpoS induces expression of the Vibrio anguillarum quorum-sensing regulator VanT.

PubMed

Weber, Barbara; Croxatto, Antony; Chen, Chang; Milton, Debra L

2008-03-01

In vibrios, regulation of the Vibrio harveyi-like LuxR transcriptional activators occurs post-transcriptionally via small regulatory RNAs (sRNAs) that destabilize the luxR mRNA at a low cell population, eliminating expression of LuxR. Expression of the sRNAs is modulated by the vibrio quorum-sensing phosphorelay systems. However, vanT mRNA, which encodes a LuxR homologue in Vibrio anguillarum, is abundant at low and high cell density, indicating that VanT expression may be regulated via additional mechanisms. In this study, Western analyses showed that VanT was expressed throughout growth with a peak of expression during late exponential growth. VanO induced partial destabilization of vanT mRNA via activation of at least one Qrr sRNA. Interestingly, the sigma factor RpoS significantly stabilized vanT mRNA and induced VanT expression during late exponential growth. This induction was in part due to RpoS repressing expression of Hfq, an RNA chaperone. RpoS is not part of the quorum-sensing regulatory cascade since RpoS did not regulate expression or activity of VanO, and RpoS was not regulated by VanO or VanT. VanT and RpoS were needed for survival following UV irradiation and for pigment and metalloprotease production, suggesting that RpoS works with the quorum-sensing systems to modulate expression of VanT, which regulates survival and stress responses.

Firing patterns in the adaptive exponential integrate-and-fire model.

PubMed

Naud, Richard; Marcille, Nicolas; Clopath, Claudia; Gerstner, Wulfram

2008-11-01

For simulations of large spiking neuron networks, an accurate, simple and versatile single-neuron modeling framework is required. Here we explore the versatility of a simple two-equation model: the adaptive exponential integrate-and-fire neuron. We show that this model generates multiple firing patterns depending on the choice of parameter values, and present a phase diagram describing the transition from one firing type to another. We give an analytical criterion to distinguish between continuous adaption, initial bursting, regular bursting and two types of tonic spiking. Also, we report that the deterministic model is capable of producing irregular spiking when stimulated with constant current, indicating low-dimensional chaos. Lastly, the simple model is fitted to real experiments of cortical neurons under step current stimulation. The results provide support for the suitability of simple models such as the adaptive exponential integrate-and-fire neuron for large network simulations.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking.

PubMed

Hamed, Kaveh Akbari; Gregg, Robert D

2016-07-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg.

An efficient quantum algorithm for spectral estimation

NASA Astrophysics Data System (ADS)

Steffens, Adrian; Rebentrost, Patrick; Marvian, Iman; Eisert, Jens; Lloyd, Seth

2017-03-01

We develop an efficient quantum implementation of an important signal processing algorithm for line spectral estimation: the matrix pencil method, which determines the frequencies and damping factors of signals consisting of finite sums of exponentially damped sinusoids. Our algorithm provides a quantum speedup in a natural regime where the sampling rate is much higher than the number of sinusoid components. Along the way, we develop techniques that are expected to be useful for other quantum algorithms as well—consecutive phase estimations to efficiently make products of asymmetric low rank matrices classically accessible and an alternative method to efficiently exponentiate non-Hermitian matrices. Our algorithm features an efficient quantum-classical division of labor: the time-critical steps are implemented in quantum superposition, while an interjacent step, requiring much fewer parameters, can operate classically. We show that frequencies and damping factors can be obtained in time logarithmic in the number of sampling points, exponentially faster than known classical algorithms.

Decentralized Feedback Controllers for Exponential Stabilization of Hybrid Periodic Orbits: Application to Robotic Walking*

PubMed Central

Hamed, Kaveh Akbari; Gregg, Robert D.

2016-01-01

This paper presents a systematic algorithm to design time-invariant decentralized feedback controllers to exponentially stabilize periodic orbits for a class of hybrid dynamical systems arising from bipedal walking. The algorithm assumes a class of parameterized and nonlinear decentralized feedback controllers which coordinate lower-dimensional hybrid subsystems based on a common phasing variable. The exponential stabilization problem is translated into an iterative sequence of optimization problems involving bilinear and linear matrix inequalities, which can be easily solved with available software packages. A set of sufficient conditions for the convergence of the iterative algorithm to a stabilizing decentralized feedback control solution is presented. The power of the algorithm is demonstrated by designing a set of local nonlinear controllers that cooperatively produce stable walking for a 3D autonomous biped with 9 degrees of freedom, 3 degrees of underactuation, and a decentralization scheme motivated by amputee locomotion with a transpelvic prosthetic leg. PMID:27990059

Adult Age Differences and the Role of Cognitive Resources in Perceptual–Motor Skill Acquisition: Application of a Multilevel Negative Exponential Model

PubMed Central

Kennedy, Kristen M.; Rodrigue, Karen M.; Lindenberger, Ulman; Raz, Naftali

2010-01-01

The effects of advanced age and cognitive resources on the course of skill acquisition are unclear, and discrepancies among studies may reflect limitations of data analytic approaches. We applied a multilevel negative exponential model to skill acquisition data from 80 trials (four 20-trial blocks) of a pursuit rotor task administered to healthy adults (19–80 years old). The analyses conducted at the single-trial level indicated that the negative exponential function described performance well. Learning parameters correlated with measures of task-relevant cognitive resources on all blocks except the last and with age on all blocks after the second. Thus, age differences in motor skill acquisition may evolve in 2 phases: In the first, age differences are collinear with individual differences in task-relevant cognitive resources; in the second, age differences orthogonal to these resources emerge. PMID:20047985

Classical versus quantum dynamical chaos: Sensitivity to external perturbations, stability and reversibility

NASA Astrophysics Data System (ADS)

Sokolov, Valentin V.; Zhirov, Oleg V.; Kharkov, Yaroslav A.

The extraordinary complexity of classical trajectories of typical nonlinear systems that manifest stochastic behavior is intimately connected with exponential sensitivity to small variations of initial conditions and/or weak external perturbations. In rigorous terms, such classical systems are characterized by positive algorithmic complexity described by the Lyapunov exponent or, alternatively, by the Kolmogorov-Sinai entropy. The said implies that, in spite of the fact that, formally, any however complex trajectory of a perfectly isolated (closed) system is unique and differentiable for any certain initial conditions and the motion is perfectly reversible, it is impractical to treat that sort of classical systems as closed ones. Inevitably, arbitrary weak influence of an environment crucially impacts the dynamics. This influence, that can be considered as a noise, rapidly effaces the memory of initial conditions and turns the motion into an irreversible random process. In striking contrast, the quantum mechanics of the classically chaotic systems exhibit much weaker sensitivity and strong memory of the initial state. Qualitatively, this crucial difference could be expected in view of a much simpler structure of quantum states as compared to the extraordinary complexity of random and unpredictable classical trajectories. However the very notion of trajectories is absent in quantum mechanics so that the concept of exponential instability seems to be irrelevant in this case. The problem of a quantitative measure of complexity of a quantum state of motion, that is a very important and nontrivial issue of the theory of quantum dynamical chaos, is the one of our concern. With such a measure in hand, we quantitatively analyze the stability and reversibility of quantum dynamics in the presence of external noise. To solve this problem we point out that individual classical trajectories are of minor interest if the motion is chaotic. Properties of all of them are alike in this case and rather the behavior of their manifolds carries really valuable information. Therefore the phase-space methods and, correspondingly, the Liouville form of the classical mechanics become the most adequate. It is very important that, opposite to the classical trajectories, the classical phase space distribution and the Liouville equation have direct quantum analogs. Hence, the analogy and difference of classical and quantum dynamics can be traced by comparing the classical (W(c)(I,θ;t)) and quantum (Wigner function W(I,θ;t)) phase space distributions both expressed in identical phase-space variables but ruled by different(!) linear equations. The paramount property of the classical dynamical chaos is the exponentially fast structuring of the system's phase space on finer and finer scales. On the contrary, degree of structuring of the corresponding Wigner function is restricted by the quantization of the phase space. This makes Wigner function more coarse and relatively "simple" as compared to its classical counterpart. Fourier analysis affords quite suitable ground for analyzing complexity of a phase space distribution, that is equally valid in classical and quantum cases. We demonstrate that the typical number of Fourier harmonics is indeed a relevant measure of complexity of states of motion in both classical as well as quantum cases. This allowed us to investigate in detail and introduce a quantitative measure of sensitivity to an external noisy environment and formulate the conditions under which the quantum motion remains reversible. It turns out that while the mean number of harmonics of the classical phase-space distribution of a non-integrable system grows with time exponentially during the whole time of the motion, the time of exponential upgrowth of this number in the case of the corresponding quantum Wigner function is restricted only to the Ehrenfest interval 0 < t < tE - just the interval within which the Wigner function still satisfies the classical Liouville equation. We showed that the number of harmonics increases beyond this interval algebraically. This fact gains a crucial importance when the Ehrenfest time is so short that the exponential regime has no time to show up. Under this condition the quantum motion turns out to be quite stable and reversible.

Modification of acute and late-phase allergic responses to ovalbumin with lipopolysaccharide.

PubMed

Tulic, Mark K; Holt, Patrick G; Sly, Peter D

2002-10-01

We have previously shown that lipopolysaccharide (LPS) exposure in sensitised animals 18 h after ovalbumin (OVA) challenge inhibits OVA-induced airway hyper-responsiveness (AHR). In the present study, we investigated the effect of LPS on OVA-induced acute and late-phase allergic responses in sensitised rats when challenged with OVA. Rats were sensitised with OVA and 11 days later challenged with 1% OVA in the presence or absence of LPS (0.5-50 microg/ml) given in the same nebulizer. Acute responses to OVA were measured each minute for 30 min after challenge. In a separate group of animals, late-phase responses to OVA were determined at 24 h. At the end of each study, Evans blue dye was injected and animals sacrificed 30 min later. Bronchoalveolar lavage was obtained to monitor inflammatory cell migration and microvascular leakage. OVA challenge in sensitised animals produced an acute response with changes in lung mechanics peaking 10.0 +/- 0.9 min after OVA and returning to baseline within 30 min. This was followed 24 h later by increased responses to methacholine chloride (MCh), inflammatory cell influx and increased Evans blue leakage into the lungs. Presence of 5 or 50 microg/ml LPS in the nebulizer during OVA challenge altered the kinetics of the acute-phase response, with an immediate decrease in lung function (time to peak decreased from 10.3 +/- 1.2 to 1.8 +/- 0.2 and 2.2 +/- 0.3 min, respectively: p < 0.001, n = 6) and a dose-dependent attenuation of late-phase AHR, cellular influx (n = 5, p < 0.001) and Evans blue leakage (n = 5, p < 0.001) at 24 h. In summary, co-administration of OVA with LPS modifies both the acute and late-phase responses to the allergen, inducing an earlier acute change in lung function and a dose-dependent inhibition of late-phase responses to the allergen. Copyright 2002 S. Karger AG, Basel

Contrasting basin architecture and rifting style of the Vøring Basin, offshore mid-Norway and the Faroe-Shetland Basin, offshore United Kingdom

NASA Astrophysics Data System (ADS)

Schöpfer, Kateřina; Hinsch, Ralph

2017-04-01

The Vøring and the Faroe-Shetland basins are offshore deep sedimentary basins which are situated on the outer continental margin of the northeast Atlantic Ocean. Both basins are underlain by thinned continental crust whose structure is still debated. In particular the nature of the lower continental crust and the origin of high velocity bodies located at the base of the lower crust are a subject of discussion in recent literature. Regional interpretation of 2D and 3D seismic reflection data, combined with well data, suggest that both basins share several common features: (i) Pre-Cretaceous faults that are distributed across the entire basin width. (ii) Geometries of pre-Jurassic strata reflecting at least two extensional phases. (iii) Three common rift phases, Late Jurassic, Campanian-Maastrichtian and Palaeocene. (iv) Large pre-Cretaceous fault blocks that are buried by several kilometres of Cretaceous and Cenozoic strata. (iii). (v) Latest Cretaceous/Palaeocene inversion. (vi) Occurrence of partial mantle serpentinization during Early Cretaceous times, as proposed by other studies, seems improbable. The detailed analysis of the data, however, revealed significant differences between the two basins: (i) The Faroe-Shetland Basin was a fault-controlled basin during the Late Jurassic but also the Late Cretaceous extensional phase. In contrast, the Vøring Basin is dominated by the late Jurassic rifting and subsequent thermal subsidence. It exhibits only minor Late Cretaceous faults that are localised above intra-basinal and marginal highs. In addition, the Cretaceous strata in the Vøring Basin are folded. (ii) In the Vøring Basin, the locus of Late Cretaceous rifting shifted westwards, affecting mainly the western basin margin, whereas in the Faroe-Shetland Basin Late Cretaceous rifting was localised in the same area as the Late Jurassic phase, hence masking the original Jurassic geometries. (iii) Devono-Carboniferous and Aptian/Albian to Cenomanian rift phases are present in the Faroe-Shetland Basin, but are not recognisable in the Vøring Basin. (iv) Based on seismic data only, a Permian/Triassic rift phase can be suggested for the Vøring Basin, but the evidence for an equivalent rift phase in the Faroe-Shetland Basin is inconclusive. The present study demonstrates that basins developing above a complex mosaic of basement terrains accreted during orogenic phases can exhibit significant differences in their architecture. The origin of these differences may be considered to be a result of inherited pre-existing large-scale structures (e.g. pre-existing fault blocks) and/or a non-uniform crustal thickness prior to rifting.

A late wake time phase delays the human dim light melatonin rhythm.

PubMed

Burgess, Helen J; Eastman, Charmane I

2006-03-13

Short sleep/dark durations, due to late bedtimes or early wake times or both, are common in modern society. We have previously shown that a series of days with a late bedtime phase delays the human dim light melatonin rhythm, as compared to a series of days with an early bedtime, despite a fixed wake time. Here we compared the effect of an early versus late wake time with a fixed bedtime on the human dim light melatonin rhythm. Fourteen healthy subjects experienced 2 weeks of short 6h nights with an early wake time fixed at their habitual weekday wake time and 2 weeks of long 9 h nights with a wake time that occurred 3h later than the early wake time, in counterbalanced order. We found that after 2 weeks with the late wake time, the dim light melatonin onset delayed by 2.4 h and the dim light melatonin offset delayed by 2.6 h (both p < 0.001), as compared to after 2 weeks with the early wake time. These results highlight the substantial influence that wake time, likely via the associated morning light exposure, has on the timing of the human circadian clock. Furthermore, the results suggest that when people truncate their sleep by waking early their circadian clocks phase advance and when people wake late their circadian clocks phase delay.

Complex Physiology and Compound Stress Responses during Fermentation of Alkali-Pretreated Corn Stover Hydrolysate by an Escherichia coli Ethanologen

PubMed Central

Schwalbach, Michael S.; Tremaine, Mary; Marner, Wesley D.; Zhang, Yaoping; Bothfeld, William; Higbee, Alan; Grass, Jeffrey A.; Cotten, Cameron; Reed, Jennifer L.; da Costa Sousa, Leonardo; Jin, Mingjie; Balan, Venkatesh; Ellinger, James; Dale, Bruce; Kiley, Patricia J.

2012-01-01

The physiology of ethanologenic Escherichia coli grown anaerobically in alkali-pretreated plant hydrolysates is complex and not well studied. To gain insight into how E. coli responds to such hydrolysates, we studied an E. coli K-12 ethanologen fermenting a hydrolysate prepared from corn stover pretreated by ammonia fiber expansion. Despite the high sugar content (∼6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate, E. coli ceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses during an exponential growth phase, a transition phase, and the glycolytically active stationary phase. During the exponential and transition phases, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate. However, after the majority of amino acids were depleted, the cells entered stationary phase, and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin, and ethanol stress collectively limits growth, sugar utilization rates, and ethanol yields in alkali-pretreated lignocellulosic hydrolysates. PMID:22389370

Quantum algorithm for energy matching in hard optimization problems

NASA Astrophysics Data System (ADS)

Baldwin, C. L.; Laumann, C. R.

2018-06-01

We consider the ability of local quantum dynamics to solve the "energy-matching" problem: given an instance of a classical optimization problem and a low-energy state, find another macroscopically distinct low-energy state. Energy matching is difficult in rugged optimization landscapes, as the given state provides little information about the distant topography. Here, we show that the introduction of quantum dynamics can provide a speedup over classical algorithms in a large class of hard optimization problems. Tunneling allows the system to explore the optimization landscape while approximately conserving the classical energy, even in the presence of large barriers. Specifically, we study energy matching in the random p -spin model of spin-glass theory. Using perturbation theory and exact diagonalization, we show that introducing a transverse field leads to three sharp dynamical phases, only one of which solves the matching problem: (1) a small-field "trapped" phase, in which tunneling is too weak for the system to escape the vicinity of the initial state; (2) a large-field "excited" phase, in which the field excites the system into high-energy states, effectively forgetting the initial energy; and (3) the intermediate "tunneling" phase, in which the system succeeds at energy matching. The rate at which distant states are found in the tunneling phase, although exponentially slow in system size, is exponentially faster than classical search algorithms.

Low mass SN Ia and the late light curve

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

Colgate, S.A.; Fryer, C.L.; Hand, K.P.

1995-12-31

The late bolometric light curves of type Ia supernovae, when measured accurately over several years, show an exponential decay with a 56d half-life over a drop in luminosity of 8 magnitudes (10 half-lives). The late-time light curve is thought to be governed by the decay of Co{sup 56}, whose 77d half-life must then be modified to account for the observed decay time. Two mechanisms, both relying upon the positron fraction of the Co{sup 56} decay, have been proposed to explain this modification. One explanation requires a large amount of emission at infra-red wavelengths where it would not be detected. Themore » other explanation has proposed a progressive transparency or leakage of the high energy positrons (Colgate, Petschek and Kriese, 1980). For the positrons to leak out of the expanding nebula at the required rate necessary to produce the modified 56d exponential, the mass of the ejecta from a one foe (10{sup 51} erg in kinetic energy) explosion must be small, M{sub ejec} = 0.4M{sub {circle_dot}} with M{sub ejec} {proportional_to} KE{sup 0.5}. Thus, in this leakage explanation, any reasonable estimate of the total energy of the explosion requires that the ejected mass be very much less than the Chandrasekhar mass of 1.4M{sub {circle_dot}}. This is very difficult to explain with the ``canonical`` Chandrasekhar-mass thermonuclear explosion that disintegrates the original white dwarf star. This result leads us to pursue alternate mechanisms of type Ia supernovae. These mechanisms include sub-Chandrasekhar thermonuclear explosions and the accretion induced collapse of Chandrasekhar mass white dwarfs. We will summarize the advantages and disadvantages of both mechanisms with considerable detail spent on our new accretion induced collapse simulations. These mechanisms lead to lower Ni{sup 56} production and hence result in type Ia supernovae with luminosities decreased down to {approximately} 50% that predicted by the ``standard`` model.« less

Quantum mechanical generalized phase-shift approach to atom-surface scattering: a Feshbach projection approach to dealing with closed channel effects.

PubMed

Maji, Kaushik; Kouri, Donald J

2011-03-28

We have developed a new method for solving quantum dynamical scattering problems, using the time-independent Schrödinger equation (TISE), based on a novel method to generalize a "one-way" quantum mechanical wave equation, impose correct boundary conditions, and eliminate exponentially growing closed channel solutions. The approach is readily parallelized to achieve approximate N(2) scaling, where N is the number of coupled equations. The full two-way nature of the TISE is included while propagating the wave function in the scattering variable and the full S-matrix is obtained. The new algorithm is based on a "Modified Cayley" operator splitting approach, generalizing earlier work where the method was applied to the time-dependent Schrödinger equation. All scattering variable propagation approaches to solving the TISE involve solving a Helmholtz-type equation, and for more than one degree of freedom, these are notoriously ill-behaved, due to the unavoidable presence of exponentially growing contributions to the numerical solution. Traditionally, the method used to eliminate exponential growth has posed a major obstacle to the full parallelization of such propagation algorithms. We stabilize by using the Feshbach projection operator technique to remove all the nonphysical exponentially growing closed channels, while retaining all of the propagating open channel components, as well as exponentially decaying closed channel components.

Proline 54 trans-cis isomerization is responsible for the kinetic partitioning at the last-step photocycle of photoactive yellow protein

PubMed Central

Lee, Byoung-Chul; Hoff, Wouter D.

2008-01-01

Photoactive yellow protein (PYP), a blue-light photoreceptor for Ectothiorhodospira halophila, has provided a unique system for studying protein folding that is coupled with a photocycle. Upon receptor activation by blue light, PYP proceeds through a photocycle that includes a partially folded signaling state. The last-step photocycle is a thermal recovery reaction from the signaling state to the native state. Bi-exponential kinetics had been observed for the last-step photocycle; however, the slow phase of the bi-exponential kinetics has not been extensively studied. Here we analyzed both fast and slow phases of the last-step photocycle in PYP. From the analysis of the denaturant dependence of the fast and slow phases, we found that the last-step photocycle proceeds through parallel channels of the folding pathway. The burial of the solvent-accessible area was responsible for the transition state of the fast phase, while structural rearrangement from the compact state to the native state was responsible for the transition state of the slow phase. The photocycle of PYP was linked to the thermodynamic cycle that includes both unfolding and refolding of the fast- and slow-phase intermediates. In order to test the hypothesis of proline-limited folding for the slow phase, we constructed two proline mutants: P54A and P68A. We found that only a single phase of the last-step photocycle was observed in P54A. This suggests that there is a low energy barrier between trans to cis conformation in P54 in the light-induced state of PYP, and the resulting cis conformation of P54 generates a slow-phase kinetic trap during the photocycle-coupled folding pathway of PYP. PMID:18794212

A Gaussian measure of quantum phase noise

NASA Technical Reports Server (NTRS)

Schleich, Wolfgang P.; Dowling, Jonathan P.

1992-01-01

We study the width of the semiclassical phase distribution of a quantum state in its dependence on the average number of photons (m) in this state. As a measure of phase noise, we choose the width, delta phi, of the best Gaussian approximation to the dominant peak of this probability curve. For a coherent state, this width decreases with the square root of (m), whereas for a truncated phase state it decreases linearly with increasing (m). For an optimal phase state, delta phi decreases exponentially but so does the area caught underneath the peak: all the probability is stored in the broad wings of the distribution.

Effects of Nitroglycerin on Regional Myocardial Blood Flow in Coronary Artery Disease

PubMed Central

Horwitz, Lawrence D.; Gorlin, Richard; Taylor, Warren J.; Kemp, Harvey G.

1971-01-01

Regional myocardial blood flow before and after sublingual nitroglycerin was measured in 10 patients with coronary artery disease. During thoracotomy, 133Xe was injected directly into the subepicardium in diseased regions of the anterior left ventricular wall, and washout rates were recorded with a scintillation counter. All disappearance curves were closely approximated by two exponential decays analyzed as two parallel flow systems by the compartmental method. The appearance of a double exponential decay pattern in diseased regions suggests that the slow phase was associated with collateral blood flow, although nonhomogeneous myocardium-to-blood partition coefficients for xenon cannot be excluded. Nitroglycerin increased the rapid phase flow in 9 of 10 patients and the slow flow in 7 of 10 patients. Average flow increased in 9 of the 10 patients (P < 0.01). Mean rapid phase flow in the control state was 110 ml/100 g per min and after nitroglycerin increased to 132 ml/100 g per min (P < 0.01); slow phase flow increased from 12 ml/100 g per min to 15 ml/100 g per min (P < 0.05). It is concluded that, under these conditions, nitroglycerin improves perfusion in regions of diseased myocardium in patients with coronary artery disease. PMID:4999635

Antagonistic Potential of Native Trichoderma viride Strain against Potent Tea Fungal Pathogens in North East India.

PubMed

Naglot, A; Goswami, S; Rahman, I; Shrimali, D D; Yadav, Kamlesh K; Gupta, Vikas K; Rabha, Aprana Jyoti; Gogoi, H K; Veer, Vijay

2015-09-01

Indigenous strains of Trichoderma species isolated from rhizosphere soils of Tea gardens of Assam, north eastern state of India were assessed for in vitro antagonism against two important tea fungal pathogens namely Pestalotia theae and Fusarium solani. A potent antagonist against both tea pathogenic fungi, designated as SDRLIN1, was selected and identified as Trichoderma viride. The strain also showed substantial antifungal activity against five standard phytopathogenic fungi. Culture filtrate collected from stationary growth phase of the antagonist demonstrated a significantly higher degree of inhibitory activity against all the test fungi, demonstrating the presence of an optimal blend of extracellular antifungal metabolites. Moreover, quantitative enzyme assay of exponential and stationary culture filtrates revealed that the activity of cellulase, β-1,3-glucanase, pectinase, and amylase was highest in the exponential phase, whereas the activity of proteases and chitinase was noted highest in the stationary phase. Morphological changes such as hyphal swelling and distortion were also observed in the fungal pathogen grown on potato dextrose agar containing stationary phase culture filtrate. Moreover, the antifungal activity of the filtrate was significantly reduced but not entirely after heat or proteinase K treatment, demonstrating substantial role of certain unknown thermostable antifungal compound(s) in the inhibitory activity.

Dynamic light scattering: A fast and reliable method to analyze bacterial growth during the lag phase.

PubMed

Vargas, Susana; Millán-Chiu, Blanca E; Arvizu-Medrano, Sofía M; Loske, Achim M; Rodríguez, Rogelio

2017-06-01

A comparison between plate counting (PC) and dynamic light scattering (DLS) is reported. PC is the standard technique to determine bacterial population as a function of time; however, this method has drawbacks, such as the cumbersome preparation and handling of samples, as well as the long time required to obtain results. Alternative methods based on optical density are faster, but do not distinguish viable from non-viable cells. These inconveniences are overcome by using DLS. Two different bacteria strains were considered: Escherichia coli and Staphylococcus aureus. DLS was performed at two different illuminating conditions: continuous and intermittent. By the increment of particle size as a function of time, it was possible to observe cell division and the formation of aggregates containing very few bacteria. The scattered intensity profiles showed the lag phase and the transition to the exponential phase of growth, providing a quantity proportional to viable bacteria concentration. The results revealed a clear and linear correlation in both lag and exponential phase, between the Log 10 (colony-forming units/mL) from PC and the Log 10 of the scattered intensity I s from DLS. These correlations provide a good support to use DLS as an alternative technique to determine bacterial population. Copyright © 2017 Elsevier B.V. All rights reserved.

Antagonistic Potential of Native Trichoderma viride Strain against Potent Tea Fungal Pathogens in North East India

PubMed Central

Naglot, A.; Goswami, S.; Rahman, I.; Shrimali, D. D.; Yadav, Kamlesh K.; Gupta, Vikas K.; Rabha, Aprana Jyoti; Gogoi, H. K.; Veer, Vijay

2015-01-01

Indigenous strains of Trichoderma species isolated from rhizosphere soils of Tea gardens of Assam, north eastern state of India were assessed for in vitro antagonism against two important tea fungal pathogens namely Pestalotia theae and Fusarium solani. A potent antagonist against both tea pathogenic fungi, designated as SDRLIN1, was selected and identified as Trichoderma viride. The strain also showed substantial antifungal activity against five standard phytopathogenic fungi. Culture filtrate collected from stationary growth phase of the antagonist demonstrated a significantly higher degree of inhibitory activity against all the test fungi, demonstrating the presence of an optimal blend of extracellular antifungal metabolites. Moreover, quantitative enzyme assay of exponential and stationary culture filtrates revealed that the activity of cellulase, β-1,3-glucanase, pectinase, and amylase was highest in the exponential phase, whereas the activity of proteases and chitinase was noted highest in the stationary phase. Morphological changes such as hyphal swelling and distortion were also observed in the fungal pathogen grown on potato dextrose agar containing stationary phase culture filtrate. Moreover, the antifungal activity of the filtrate was significantly reduced but not entirely after heat or proteinase K treatment, demonstrating substantial role of certain unknown thermostable antifungal compound(s) in the inhibitory activity. PMID:26361476

Important role of catalase in the cellular response of the budding yeast Saccharomyces cerevisiae exposed to ionizing radiation.

PubMed

Nishimoto, Takuto; Furuta, Masakazu; Kataoka, Michihiko; Kishida, Masao

2015-03-01

Ionizing radiation indirectly causes oxidative stress in cells via reactive oxygen species (ROS), such as hydroxyl radicals (OH(-)) generated by the radiolysis of water. We investigated how the catalase function was affected by ionizing radiation and analyzed the phenotype of mutants with a disrupted catalase gene in Saccharomyces cerevisiae exposed to radiation. The wild-type yeast strain and isogenic mutants with disrupted catalase genes were exposed to various doses of (60)Co gamma-rays. There was no difference between the wild-type strain and the cta1 disruption mutant following exposure to gamma-ray irradiation. In contrast, there was a significant decrease in the ctt1 disruption mutant, suggesting that this strain exhibited decreased survival on gamma-ray exposure compared with other strains. In all three strains, stationary phase cells were more tolerant to the exposure of gamma-rays than exponential phase cells, whereas the catalase activity in the wild-type strain and cta1 disruption mutant was higher in the stationary phase than in the exponential phase. These data suggest a correlation between catalase activity and survival following gamma-ray exposure. However, this correlation was not clear in the ctt1 disruption mutant, suggesting that other factors are involved in the tolerance to ROS induced by irradiation.

Nonequilibrium Phase Transition in a Periodically Driven XY Spin Chain

NASA Astrophysics Data System (ADS)

Prosen, Tomaž; Ilievski, Enej

2011-08-01

We present a general formulation of Floquet states of periodically time-dependent open Markovian quasifree fermionic many-body systems in terms of a discrete Lyapunov equation. Illustrating the technique, we analyze periodically kicked XY spin-(1)/(2) chain which is coupled to a pair of Lindblad reservoirs at its ends. A complex phase diagram is reported with reentrant phases of long range and exponentially decaying spin-spin correlations as some of the system’s parameters are varied. The structure of phase diagram is reproduced in terms of counting nontrivial stationary points of Floquet quasiparticle dispersion relation.

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

Zhang, Chundong; Zhang, Ying; Li, Yi

Recently, we have demonstrated that proline-rich protein 11 (PRR11) is a novel tumor-related gene product likely implicated in the regulation of cell cycle progression as well as lung cancer development. However, its precise role in cell cycle progression remains unclear. In the present study, we have further investigated the expression pattern and functional implication of PRR11 during cell cycle in detail in human lung carcinoma-derived H1299 cells. According to our immunofluorescence study, PRR11 was expressed largely in cytoplasm, the amount of PRR11 started to increase in the late S phase, and was retained until just before mitotic telophase. Consistent withmore » those observations, siRNA-mediated knockdown of PRR11 caused a significant cell cycle arrest in the late S phase. Intriguingly, the treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. Moreover, knockdown of PRR11 also resulted in a remarkable retardation of G2/M progression, and PRR11-knockdown cells subsequently underwent G2 phase cell cycle arrest accompanied by obvious mitotic defects such as multipolar spindles and multiple nuclei. In addition, forced expression of PRR11 promoted the premature Chromatin condensation (PCC), and then proliferation of PRR11-expressing cells was massively attenuated and induced apoptosis. Taken together, our current observations strongly suggest that PRR11, which is strictly regulated during cell cycle progression, plays a pivotal role in the regulation of accurate cell cycle progression through the late S phase to mitosis. - Highlights: • PRR11 started to increase in the late S phase and was retained until just before mitotic telophase. • PRR11-knockdown caused a significant cell cycle arrest in the late S phase and G2 phase. • The treatment with dNTPs further augmented PRR11 silencing-mediated S phase arrest. • PRR11-knockdown led to multipolar spindles and multiple nuclei. • Forced expression of PRR11 promoted the PCC and inhibited cell proliferation.« less

Dark Matter Coannihilation with a Lighter Species

NASA Astrophysics Data System (ADS)

Berlin, Asher

2017-09-01

We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, MGUT˜1016 GeV .

Dark Matter Coannihilation with a Lighter Species.

PubMed

Berlin, Asher

2017-09-22

We propose a new thermal freeze-out mechanism for ultraheavy dark matter. Dark matter coannihilates with a lighter unstable species that is nearby in mass, leading to an annihilation rate that is exponentially enhanced relative to standard weakly interactive massive particles. This scenario destabilizes any potential dark matter candidate. In order to remain consistent with astrophysical observations, our proposal necessitates very long-lived states, motivating striking phenomenology associated with the late decays of ultraheavy dark matter, potentially as massive as the scale of grand unified theories, M_{GUT}∼10^{16}  GeV.

Freezing of simple systems using density functional theory

NASA Astrophysics Data System (ADS)

de Kuijper, A.; Vos, W. L.; Barrat, J.-L.; Hansen, J.-P.; Schouten, J. A.

1990-10-01

Density functional theory (DFT) has been applied to the study of the fluid-solid transition in systems with realistic potentials (soft cores and attractive forces): the purely repulsive WCA Lennard-Jones reference potential (LJT), the full Lennard-Jones potential (LJ) and the exponential-6 potential appropriate for helium and hydrogen. Three different DFT formalisms were used: the formulation of Haymet and Oxtoby (HO) and the new theories of Denton and Ashcroft (MWDA) and of Baus (MELA). The results for the melting pressure are compared with recent simulation and experimental data. The results of the HO version are always too high, the deviation increasing when going from the repulsive Lennard-Jones to the exponential-6 potential of H2. The MWDA gives too low results for the repulsive Lennard-Jones potential. At low temperatures, it fails for the full LJ potential while at high temperatures it is in good agreement. Including the attraction as a mean-field correction gives good results also for low temperatures. The MWDA results are too high for the exponential-6 potentials. The MELA fails completely for the LJT potential and the hydrogen exponential-6 potential, since it does not give a stable solid phase.

Mechanical energy fluctuations in granular chains: the possibility of rogue fluctuations or waves.

PubMed

Han, Ding; Westley, Matthew; Sen, Surajit

2014-09-01

The existence of rogue or freak waves in the ocean has been known for some time. They have been reported in the context of optical lattices and the financial market. We ask whether such waves are generic to late time behavior in nonlinear systems. In that vein, we examine the dynamics of an alignment of spherical elastic beads held within fixed, rigid walls at zero precompression when they are subjected to sufficiently rich initial conditions. Here we define such waves generically as unusually large energy fluctuations that sustain for short periods of time. Our simulations suggest that such unusually large fluctuations ("hot spots") and occasional series of such fluctuations through space and time ("rogue fluctuations") are likely to exist in the late time dynamics of the granular chain system at zero dissipation. We show that while hot spots are common in late time evolution, rogue fluctuations are seen in purely nonlinear systems (i.e., no precompression) at late enough times. We next show that the number of such fluctuations grows exponentially with increasing nonlinearity whereas rogue fluctuations decrease superexponentially with increasing precompression. Dissipation-free granular alignment systems may be possible to realize as integrated circuits and hence our observations may potentially be testable in the laboratory.

Quantum localization and bound-state formation in Bose-Einstein condensates

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

Franzosi, Roberto; Giampaolo, Salvatore M.; Illuminati, Fabrizio

2010-12-15

We discuss the possibility of exponential quantum localization in systems of ultracold bosonic atoms with repulsive interactions in open optical lattices without disorder. We show that exponential localization occurs in the maximally excited state of the lowest energy band. We establish the conditions under which the presence of the upper energy bands can be neglected, determine the successive stages and the quantum phase boundaries at which localization occurs, and discuss schemes to detect it experimentally by visibility measurements. The discussed mechanism is a particular type of quantum localization that is intuitively understood in terms of the interplay between nonlinearity andmore » a bounded energy spectrum.« less

Quantification and isotopic analysis of intracellular sulfur metabolites in the dissimilatory sulfate reduction pathway

NASA Astrophysics Data System (ADS)

Sim, Min Sub; Paris, Guillaume; Adkins, Jess F.; Orphan, Victoria J.; Sessions, Alex L.

2017-06-01

Microbial sulfate reduction exhibits a normal isotope effect, leaving unreacted sulfate enriched in 34S and producing sulfide that is depleted in 34S. However, the magnitude of sulfur isotope fractionation is quite variable. The resulting changes in sulfur isotope abundance have been used to trace microbial sulfate reduction in modern and ancient ecosystems, but the intracellular mechanism(s) underlying the wide range of fractionations remains unclear. Here we report the concentrations and isotopic ratios of sulfur metabolites in the dissimilatory sulfate reduction pathway of Desulfovibrio alaskensis. Intracellular sulfate and APS levels change depending on the growth phase, peaking at the end of exponential phase, while sulfite accumulates in the cell during stationary phase. During exponential growth, intracellular sulfate and APS are strongly enriched in 34S. The fractionation between internal and external sulfate is up to 49‰, while at the same time that between external sulfate and sulfide is just a few permil. We interpret this pattern to indicate that enzymatic fractionations remain large but the net fractionation between sulfate and sulfide is muted by the closed-system limitation of intracellular sulfate. This 'reservoir effect' diminishes upon cessation of exponential phase growth, allowing the expression of larger net sulfur isotope fractionations. Thus, the relative rates of sulfate exchange across the membrane versus intracellular sulfate reduction should govern the overall (net) fractionation that is expressed. A strong reservoir effect due to vigorous sulfate reduction might be responsible for the well-established inverse correlation between sulfur isotope fractionation and the cell-specific rate of sulfate reduction, while at the same time intraspecies differences in sulfate uptake and/or exchange rates could account for the significant scatter in this relationship. Our approach, together with ongoing investigations of the kinetic isotope fractionation by key enzymes in the sulfate reduction pathway, should provide an empirical basis for a quantitative model relating the magnitude of microbial isotope fractionation to their environmental and physiological controls.

Status Update on the NCRP Scientific Committee SC 5-1 Report: Decision Making for Late-Phase Recovery from Nuclear or Radiological Incidents - 13450

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

Chen, S.Y.

2013-07-01

In August 2008, the U.S. Department of Homeland Security (DHS) issued its final Protective Action Guide (PAG) for radiological dispersal device (RDD) and improvised nuclear device (IND) incidents. This document specifies protective actions for public health during the early and intermediate phases and cleanup guidance for the late phase of RDD or IND incidents, and it discusses approaches to implementing the necessary actions. However, while the PAG provides specific guidance for the early and intermediate phases, it prescribes no equivalent guidance for the late-phase cleanup actions. Instead, the PAG offers a general description of a complex process using a site-specificmore » optimization approach. This approach does not predetermine cleanup levels but approaches the problem from the factors that would bear on the final agreed-on cleanup levels. Based on this approach, the decision-making process involves multifaceted considerations including public health, the environment, and the economy, as well as socio-political factors. In an effort to fully define the process and approach to be used in optimizing late-phase recovery and site restoration following an RDD or IND incident, DHS has tasked the NCRP with preparing a comprehensive report addressing all aspects of the optimization process. Preparation of the NCRP report is a three-year (2010-2013) project assigned to a scientific committee, the Scientific Committee (SC) 5-1; the report was initially titled, Approach to Optimizing Decision Making for Late- Phase Recovery from Nuclear or Radiological Terrorism Incidents. Members of SC 5-1 represent a broad range of expertise, including homeland security, health physics, risk and decision analysis, economics, environmental remediation and radioactive waste management, and communication. In the wake of the Fukushima nuclear accident of 2011, and guided by a recent process led by the White House through a Principal Level Exercise (PLE), the optimization approach has since been expanded to include off-site contamination from major nuclear power plant accidents as well as other nuclear or radiological incidents. The expanded application under the current guidance has thus led to a broadened scope of the report, which is reflected in its new title, Decision Making for Late-Phase Recovery from Nuclear or Radiological Incidents. The NCRP report, which is due for publication in 2013, will substantiate the current DHS guidance by clarifying and elaborating on the processes required for the development and implementation of procedures for optimizing decision making for late-phase recovery, enabling the establishment of cleanup goals on a site-specific basis. The report will contain a series of topics addressing important issues related to the long-term recovery from nuclear or radiological incidents. Special topics relevant to supporting the optimization of the decision-making process will include cost-benefit analysis, radioactive waste management, risk communication, stakeholder interaction, risk assessment, and decontamination approaches and techniques. The committee also evaluated past nuclear and radiological incidents for their relevance to the report, including the emerging issues associated with the Fukushima nuclear accident. Thus, due to the commonality of the late-phase issues (such as the potential widespread contamination following an event), the majority of the information pertaining to the response in the late-phase decision-making period, including site-specific optimization framework and approach, could be used or adapted for use in case of similar situations that are not due to terrorism, such as those that would be caused by major nuclear facility accidents or radiological incidents. To ensure that the report and the NCRP recommendations are current and relevant to the effective implementation of federal guidance, SC 5-1 has actively coordinated with the agencies of interest and other relevant stakeholders throughout the duration of the project. The resulting report will be an important resource to guide those involved in late-phase recovery efforts following a nuclear or radiological incident. (authors)« less

On the hardness of high carbon ferrous martensite

NASA Astrophysics Data System (ADS)

Mola, J.; Ren, M.

2018-06-01

Due to the presence of retained austenite in martensitic steels, especially steels with high carbon concentrations, it is difficult to estimate the hardness of martensite independent of the hardness of the coexisting austenite. In the present work, the hardness of ferrous martensite with carbon concentrations in the range 0.23-1.46 mass-% was estimated by the regression analysis of hardnesses for hardened martensitic-austenitic steels containing various martensite fractions. For a given carbon concentration, the hardness of martensitic-austenitic steels was found to increase exponentially with an increase in the fraction of the martensitic constituent. The hardness of the martensitic constituent was subsequently estimated by the exponential extrapolation of the hardness of phase mixtures to 100 vol.% martensite. For martensite containing 1.46 mass-% carbon, the hardness was estimated to be 1791 HV. This estimate of martensite hardness is significantly higher than the experimental hardness of 822 HV for a phase mixture of 68 vol.% martensite and 32 vol.% austenite. The hardness obtained by exponential extrapolation is also much higher than the hardness of 1104 HV based on the rule of mixtures. The underestimated hardness of high carbon martensite in the presence of austenite is due to the non-linear dependence of hardness on the martensite fraction. The latter is also a common observation in composite materials with a soft matrix and hard reinforcing particles.

Stress within a Restricted Time Window Selectively Affects the Persistence of Long-Term Memory

PubMed Central

Fang, Qin; Chai, Ning; Zhao, Li-Yan; Xue, Yan-Xue; Luo, Yi-Xiao; Jian, Min; Han, Ying; Shi, Hai-Shui; Lu, Lin; Wu, Ping; Wang, Ji-Shi

2013-01-01

The effects of stress on emotional memory are distinct and depend on the stages of memory. Memory undergoes consolidation and reconsolidation after acquisition and retrieval, respectively. Stress facilitates the consolidation but disrupts the reconsolidation of emotional memory. Previous research on the effects of stress on memory have focused on long-term memory (LTM) formation (tested 24 h later), but the effects of stress on the persistence of LTM (tested at least 1 week later) are unclear. Recent findings indicated that the persistence of LTM requires late-phase protein synthesis in the dorsal hippocampus. The present study investigated the effect of stress (i.e., cold water stress) during the late phase after the acquisition and retrieval of contextual fear memory in rats. We found that stress and corticosterone administration during the late phase (12 h) after acquisition, referred to as late consolidation, selectively enhanced the persistence of LTM, whereas stress during the late phase (12 h) after retrieval, referred to as late reconsolidation, selectively disrupted the restabilized persistence of LTM. Moreover, the effects of stress on the persistence of LTM were blocked by the corticosterone synthesis inhibitor metyrapone, which was administered before stress, suggesting that the glucocorticoid system is involved in the effects of stress on the persistence of LTM. We conclude that stress within a restricted time window after acquisition or retrieval selectively affects the persistence of LTM and depends on the glucocorticoid system. PMID:23544051

The Effect of Gabapentin and Ketorolac on Allodynia and Conditioned Place Preference in Antibody-Induced Inflammation

PubMed Central

Park, HJ; Sandor, K; McQueen, J; Woller, SA; Svensson, CI; Corr, MP; Yaksh, TL

2018-01-01

Background Glucose-6-phosphate isomerase and collagen type II antibody induced arthritis models (K/BxN and CAIA, respectively) have an inflammatory and a post-inflammatory phase. Both phases display robust tactile allodynia. In previous work, inflammatory phase allodynia was reversed by gabapentin and ketorolac, whereas in late phase only gabapentin was effective. Here we sought to determine if the effects of these two drugs during the early and late phases of the two arthritis models were observed in the conditioned place preference (CPP) paradigm, indicating a differential drug effect on the aversive state. Methods Male C57BL/6 mice received K/BxN serum intraperitoneally, while male BALB/c mice received collagen type II antibody cocktail intravenously. After onset of inflammation and allodynia, we assessed effects of i.p. gabapentin (100 mg/kg) or ketorolac (15 mg/kg) using a CPP paradigm: 2 days adaptation, 2 days conditioning (vehicle in morning and drug in afternoon), preference testing on day 5. Results Consistent with the effects upon allodynia, both gabapentin and ketorolac produced a preference for the drug-paired compartment in the early phase of the K/BxN model, while gabapentin, but not ketorolac, resulted in a place preference during late phase. In the CAIA model, consistent with differential effects upon allodynia, gabapentin produced a preference in the early phase and a trend in the late phase, whereas ketorolac was ineffective at either time. Conclusions CPP validated the aversive state in the inflammatory and post-inflammatory phases of the K/BxN and CAIA arthritis models and correspondence between the anti-hyperpathic pharmacology as defined by thresholds and CPP. PMID:26517300

The effect of gabapentin and ketorolac on allodynia and conditioned place preference in antibody-induced inflammation.

PubMed

Park, H J; Sandor, K; McQueen, J; Woller, S A; Svensson, C I; Corr, M; Yaksh, T L

2016-07-01

Glucose-6-phosphate isomerase and collagen type II antibody-induced arthritis models (K/BxN and CAIA, respectively) have an inflammatory and a post-inflammatory phase. Both phases display robust tactile allodynia. In previous work, inflammatory phase allodynia was reversed by gabapentin and ketorolac, whereas in late phase only gabapentin was effective. Here, we sought to determine if the effects of these two drugs during the early and late phases of the two arthritis models were observed in the conditioned place preference (CPP) paradigm, indicating a differential drug effect on the aversive state. Male C57BL/6 mice received K/BxN serum intraperitoneally, while male BALB/c mice received collagen type II antibody cocktail intravenously. After onset of inflammation and allodynia, we assessed effects of i.p. gabapentin (100 mg/kg) or ketorolac (15 mg/kg) using a CPP paradigm: 2 days adaptation, 2 days conditioning (vehicle in morning and drug in afternoon), preference testing on day 5. Consistent with the effects upon allodynia, both gabapentin and ketorolac produced a preference for the drug-paired compartment in the early phase of the K/BxN model, while gabapentin, but not ketorolac, resulted in a place preference during late phase. In the CAIA model, consistent with differential effects upon allodynia, gabapentin produced a preference in the early phase and a trend in the late phase, whereas ketorolac was ineffective at either time. CPP validated the aversive state in the inflammatory and post-inflammatory phases of the K/BxN and CAIA arthritis models and correspondence between the anti-hyperpathic pharmacology as defined by thresholds and CPP. © 2015 European Pain Federation - EFIC®

Differences in grip force control between young and late middle-aged adults.

PubMed

Zheng, Lianrong; Li, Kunyang; Wang, Qian; Chen, Wenhui; Song, Rong; Liu, Guanzheng

2017-09-01

Grip force control is a crucial function for human to guarantee the quality of life. To examine the effects of age on grip force control, 10 young adults and 11 late middle-aged adults participated in visually guided tracking tasks using different target force levels (25, 50, and 75% of the subject's maximal grip force). Multiple measures were used to evaluate the tracking performance during force rising phase and force maintenance phase. The measurements include the rise time, fuzzy entropy, mean force percentage, coefficient of variation, and target deviation ratio. The results show that the maximal grip force was significantly lower in the late middle-aged adults than in the young adults. The time of rising phase was systematically longer among late middle-aged adults. The fuzzy entropy is a useful indicator for quantitating the force variability of the grip force signal at higher force levels. These results suggest that the late middle-aged adults applied a compensatory strategy that allow allows for sufficient time to reach the required grip force and reduce the impact of the early and subtle degenerative changes in hand motor function.

Gravimetric method for in vitro calibration of skin hydration measurements.

PubMed

Martinsen, Ørjan G; Grimnes, Sverre; Nilsen, Jon K; Tronstad, Christian; Jang, Wooyoung; Kim, Hongsig; Shin, Kunsoo; Naderi, Majid; Thielmann, Frank

2008-02-01

A novel method for in vitro calibration of skin hydration measurements is presented. The method combines gravimetric and electrical measurements and reveals an exponential dependency of measured electrical susceptance to absolute water content in the epidermal stratum corneum. The results also show that absorption of water into the stratum corneum exhibits three different phases with significant differences in absorption time constant. These phases probably correspond to bound, loosely bound, and bulk water.

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

Vasileiadis, Thomas; Department of Materials Science, University of Patras, GR-26504 Rio-Patras; Yannopoulos, Spyros N., E-mail: sny@iceht.forth.gr

Controlled photo-induced oxidation and amorphization of elemental trigonal tellurium are achieved by laser irradiation at optical wavelengths. These processes are monitored in situ by time-resolved Raman scattering and ex situ by electron microscopies. Ultrathin TeO₂ films form on Te surfaces, as a result of irradiation, with an interface layer of amorphous Te intervening between them. It is shown that irradiation, apart from enabling the controllable transformation of bulk Te to one-dimensional nanostructures, such as Te nanotubes and hybrid core-Te/sheath-TeO₂ nanowires, causes also a series of light-driven (athermal) phase transitions involving the crystallization of the amorphous TeO₂ layers and its transformationmore » to a multiplicity of crystalline phases including the γ-, β-, and α-TeO₂ crystalline phases. The kinetics of the above photo-induced processes is investigated by Raman scattering at various laser fluences revealing exponential and non-exponential kinetics at low and high fluence, respectively. In addition, the formation of ultrathin (less than 10 nm) layers of amorphous TeO₂ offers the possibility to explore structural transitions in 2D glasses by observing changes in the short- and medium-range structural order induced by spatial confinement.« less

Optimal savings and the value of population.

PubMed

Arrow, Kenneth J; Bensoussan, Alain; Feng, Qi; Sethi, Suresh P

2007-11-20

We study a model of economic growth in which an exogenously changing population enters in the objective function under total utilitarianism and into the state dynamics as the labor input to the production function. We consider an arbitrary population growth until it reaches a critical level (resp. saturation level) at which point it starts growing exponentially (resp. it stops growing altogether). This requires population as well as capital as state variables. By letting the population variable serve as the surrogate of time, we are still able to depict the optimal path and its convergence to the long-run equilibrium on a two-dimensional phase diagram. The phase diagram consists of a transient curve that reaches the classical curve associated with a positive exponential growth at the time the population reaches the critical level. In the case of an asymptotic population saturation, we expect the transient curve to approach the equilibrium as the population approaches its saturation level. Finally, we characterize the approaches to the classical curve and to the equilibrium.

Noise facilitation in associative memories of exponential capacity.

PubMed

Karbasi, Amin; Salavati, Amir Hesam; Shokrollahi, Amin; Varshney, Lav R

2014-11-01

Recent advances in associative memory design through structured pattern sets and graph-based inference algorithms have allowed reliable learning and recall of an exponential number of patterns that satisfy certain subspace constraints. Although these designs correct external errors in recall, they assume neurons that compute noiselessly, in contrast to the highly variable neurons in brain regions thought to operate associatively, such as hippocampus and olfactory cortex. Here we consider associative memories with boundedly noisy internal computations and analytically characterize performance. As long as the internal noise level is below a specified threshold, the error probability in the recall phase can be made exceedingly small. More surprising, we show that internal noise improves the performance of the recall phase while the pattern retrieval capacity remains intact: the number of stored patterns does not reduce with noise (up to a threshold). Computational experiments lend additional support to our theoretical analysis. This work suggests a functional benefit to noisy neurons in biological neuronal networks.

Optimal savings and the value of population

PubMed Central

Arrow, Kenneth J.; Bensoussan, Alain; Feng, Qi; Sethi, Suresh P.

2007-01-01

We study a model of economic growth in which an exogenously changing population enters in the objective function under total utilitarianism and into the state dynamics as the labor input to the production function. We consider an arbitrary population growth until it reaches a critical level (resp. saturation level) at which point it starts growing exponentially (resp. it stops growing altogether). This requires population as well as capital as state variables. By letting the population variable serve as the surrogate of time, we are still able to depict the optimal path and its convergence to the long-run equilibrium on a two-dimensional phase diagram. The phase diagram consists of a transient curve that reaches the classical curve associated with a positive exponential growth at the time the population reaches the critical level. In the case of an asymptotic population saturation, we expect the transient curve to approach the equilibrium as the population approaches its saturation level. Finally, we characterize the approaches to the classical curve and to the equilibrium. PMID:17984059

Dynamics of the quantum search and quench-induced first-order phase transitions.

PubMed

Coulamy, Ivan B; Saguia, Andreia; Sarandy, Marcelo S

2017-02-01

We investigate the excitation dynamics at a first-order quantum phase transition (QPT). More specifically, we consider the quench-induced QPT in the quantum search algorithm, which aims at finding out a marked element in an unstructured list. We begin by deriving the exact dynamics of the model, which is shown to obey a Riccati differential equation. Then, we discuss the probabilities of success by adopting either global or local adiabaticity strategies. Moreover, we determine the disturbance of the quantum criticality as a function of the system size. In particular, we show that the critical point exponentially converges to its thermodynamic limit even in a fast evolution regime, which is characterized by both entanglement QPT estimators and the Schmidt gap. The excitation pattern is manifested in terms of quantum domain walls separated by kinks. The kink density is then shown to follow an exponential scaling as a function of the evolution speed, which can be interpreted as a Kibble-Zurek mechanism for first-order QPTs.

Protein synthesis and the recovery of both survival and cytoplasmic "petite" mutation in ultraviolet-treated yeast cells. I. Nuclear-directed protein synthesis.

PubMed

Heude, M; Chanet, R; Moustacchi, E

1975-04-01

The contribution of nuclear-directed protein synthesis in the repair of lethal and mitochondrial genetic damage after UV-irradiation of exponential and stationary phage haploid yeast cells was examined. This was carried out using cycloheximide (CH), a specific inhibitor of nuclear protein synthesis. It appears that nuclear protein synthesis is required for the increase in survival seen after the liquid holding of cells at both stages, as well as for the "petite" recovery seen after the liquid holding of exponential phase cells. The characteristic negative liquid holding effect observed for the UV induction of "petites" in stationary phase cells (increase of the frequency of "petites" during storage) remained following all the treatments which inhibited nuclear protein synthesis. However, the application of photoreactivating light following dark holding with cycloheximide indicates that some steps of the repair of both nuclear and mitochondrial damage are performed in the absence of a synthesis of proteins.

Mycolytic enzymes produced by Streptomyces violaceusniger and their role in antagonism towards wood-rotting fungi.

PubMed

Nagpure, Anand; Choudhary, Bharti; Gupta, Rajinder K

2014-05-01

Extracellular mycolytic enzymes produced under submerged fermentation by the fungal antagonist Streptomyces violaceusniger MTCC 3959 were characterized. This streptomycete produced higher amounts of extracellular chitinase and protease during late exponential phase, whereas β-1,3-glucanase production was at peak in mid-stationary phase. Cell-free culture filtrate (CCF) exhibited a broad range of antifungal activity against both white rot and brown rot fungi. The inhibitory activity was completely lost after treatment with proteinase K and heat, indicating that extracellular antifungal metabolites are heat labile and proteinaceous in nature. Optimum pH and temperature for enzyme activity were: 9.0 and 60 °C for chitinase; 6.0 and 60 °C for β-1,3-glucanase; and 9.0 and 70 °C for protease. Mycolytic enzymes were moderately thermostable, and had a wide pH stability range extending from pH 5.0 to 10.0. The zymogram analysis of CCF revealed five chitinase isoenzymes with an apparent molecular weight of 20.8, 33.3, 45.6, 67.4, and 114.8 kDa, one β-1,3-glucanase appeared as a single band of ∼131.8 kDa and four protease isoenzymes with approximate molecular weights of 22.8, 62.52, 74.64, and 120.5 kDa. S. violaceusniger MTCC 3959 produced mycolytic enzymes that can be effectively used for suppression of phytopathogenic basidiomycetes. It has the potential to be an effective biofungicide. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Single-channel activations and concentration jumps: comparison of recombinant NR1a/NR2A and NR1a/NR2D NMDA receptors

PubMed Central

Wyllie, David J A; Béhé, Philippe; Colquhoun, David

1998-01-01

We have expressed recombinant NR1a/NR2A and NR1a/NR2D N-methyl-D-aspartate (NMDA) receptor channels in Xenopus oocytes and made recordings of single-channel and macroscopic currents in outside-out membrane patches. For each receptor type we measured (a) the individual single-channel activations evoked by low glutamate concentrations in steady-state recordings, and (b) the macroscopic responses elicited by brief concentration jumps with high agonist concentrations, and we explore the relationship between these two sorts of observation. Low concentration (5–100 nM) steady-state recordings of NR1a/NR2A and NR1a/NR2D single-channel activity generated shut-time distributions that were best fitted with a mixture of five and six exponential components, respectively. Individual activations of either receptor type were resolved as bursts of openings, which we refer to as ‘super-clusters’. During a single activation, NR1a/NR2A receptors were open for 36 % of the time, but NR1a/NR2D receptors were open for only 4 % of the time. For both, distributions of super-cluster durations were best fitted with a mixture of six exponential components. Their overall mean durations were 35.8 and 1602 ms, respectively. Steady-state super-clusters were aligned on their first openings and averaged. The average was well fitted by a sum of exponentials with time constants taken from fits to super-cluster length distributions. It is shown that this is what would be expected for a channel that shows simple Markovian behaviour. The current through NR1a/NR2A channels following a concentration jump from zero to 1 mM glutamate for 1 ms was well fitted by three exponential components with time constants of 13 ms (rising phase), 70 ms and 350 ms (decaying phase). Similar concentration jumps on NR1a/NR2D channels were well fitted by two exponentials with means of 45 ms (rising phase) and 4408 ms (decaying phase) components. During prolonged exposure to glutamate, NR1a/NR2A channels desensitized with a time constant of 649 ms, while NR1a/NR2D channels exhibited no apparent desensitization. We show that under certain conditions, the time constants for the macroscopic jump response should be the same as those for the distribution of super-cluster lengths, though the resolution of the latter is so much greater that it cannot be expected that all the components will be resolvable in a macroscopic current. Good agreement was found for jumps on NR1a/NR2D receptors, and for some jump experiments on NR1a/NR2A. However, the latter were rather variable and some were slower than predicted. Slow decays were associated with patches that had large currents. PMID:9625862

Seasonal Influenza Forecasting in Real Time Using the Incidence Decay With Exponential Adjustment Model.

PubMed

Nasserie, Tahmina; Tuite, Ashleigh R; Whitmore, Lindsay; Hatchette, Todd; Drews, Steven J; Peci, Adriana; Kwong, Jeffrey C; Friedman, Dara; Garber, Gary; Gubbay, Jonathan; Fisman, David N

2017-01-01

Seasonal influenza epidemics occur frequently. Rapid characterization of seasonal dynamics and forecasting of epidemic peaks and final sizes could help support real-time decision-making related to vaccination and other control measures. Real-time forecasting remains challenging. We used the previously described "incidence decay with exponential adjustment" (IDEA) model, a 2-parameter phenomenological model, to evaluate the characteristics of the 2015-2016 influenza season in 4 Canadian jurisdictions: the Provinces of Alberta, Nova Scotia and Ontario, and the City of Ottawa. Model fits were updated weekly with receipt of incident virologically confirmed case counts. Best-fit models were used to project seasonal influenza peaks and epidemic final sizes. The 2015-2016 influenza season was mild and late-peaking. Parameter estimates generated through fitting were consistent in the 2 largest jurisdictions (Ontario and Alberta) and with pooled data including Nova Scotia counts (R 0 approximately 1.4 for all fits). Lower R 0 estimates were generated in Nova Scotia and Ottawa. Final size projections that made use of complete time series were accurate to within 6% of true final sizes, but final size was using pre-peak data. Projections of epidemic peaks stabilized before the true epidemic peak, but these were persistently early (~2 weeks) relative to the true peak. A simple, 2-parameter influenza model provided reasonably accurate real-time projections of influenza seasonal dynamics in an atypically late, mild influenza season. Challenges are similar to those seen with more complex forecasting methodologies. Future work includes identification of seasonal characteristics associated with variability in model performance.

Delayed Noradrenergic Activation in the Dorsal Hippocampus Promotes the Long-Term Persistence of Extinguished Fear

PubMed Central

Chai, Ning; Liu, Jian-Feng; Xue, Yan-Xue; Yang, Chang; Yan, Wei; Wang, Hui-Min; Luo, Yi-Xiao; Shi, Hai-Shui; Wang, Ji-Shi; Bao, Yan-Ping; Meng, Shi-Qiu; Ding, Zeng-Bo; Wang, Xue-Yi; Lu, Lin

2014-01-01

Fear extinction has been extensively studied, but little is known about the molecular processes that underlie the persistence of extinction long-term memory (LTM). We found that microinfusion of norepinephrine (NE) into the CA1 area of the dorsal hippocampus during the early phase (0 h) after extinction enhanced extinction LTM at 2 and 14 days after extinction. Intra-CA1 infusion of NE during the late phase (12 h) after extinction selectively promoted extinction LTM at 14 days after extinction that was blocked by the β-receptor antagonist propranolol, protein kinase A (PKA) inhibitor Rp-cAMPS, and protein synthesis inhibitors anisomycin and emetine. The phosphorylation levels of PKA, cyclic adenosine monophosphate response element-binding protein (CREB), GluR1, and the membrane GluR1 level were increased by NE during the late phase after extinction that was also blocked by propranolol and Rp-cAMPS. These results suggest that the enhancement of extinction LTM persistence induced by NE requires the activation of the β-receptor/PKA/CREB signaling pathway and membrane GluR1 trafficking. Moreover, extinction increased the phosphorylation levels of Erk1/2, CREB, and GluR1, and the membrane GluR1 level during the late phase, and anisomycin/emetine alone disrupted the persistence of extinction LTM, indicating that the persistence of extinction LTM requires late-phase protein synthesis in the CA1. Propranolol and Rp-cAMPS did not completely disrupt the persistence of extinction LTM, suggesting that another β-receptor/PKA-independent mechanism underlies the persistence of extinction LTM. Altogether, our results showed that enhancing hippocampal noradrenergic activity during the late phase after extinction selectively promotes the persistence of extinction LTM. PMID:24553734

Late Mesolithic and early Neolithic forest disturbance: a high resolution palaeoecological test of human impact hypotheses

NASA Astrophysics Data System (ADS)

Innes, James B.; Blackford, Jeffrey J.; Rowley-Conwy, Peter A.

2013-10-01

The transition in north-west Europe from the hunter-gatherer societies of the Late Mesolithic to the pioneer farming societies of the early Neolithic is not well understood, either culturally or palaeoecologically. In Britain the final transition was rapid but it is unclear whether novel Neolithic attributes were introduced by immigrants who supplanted the native hunter-gatherers, or whether the latest Mesolithic foragers gradually adopted elements of the Neolithic economic package. In this study, relatively coarse- (10 mm interval) and fine-resolution (2 mm), multi-proxy palaeoecological data including pollen, charcoal and NPPs including fungi, have been used to investigate two phases of vegetation disturbance of (a) distinctly Late Mesolithic and (b) early Neolithic age, at an upland site in northern England in a region with both a Neolithic and a Late Mesolithic archaeological presence. We identify and define the palaeoecological characteristics of these two disturbance phases, about a millennium apart, in order to investigate whether differing land-use techniques can be identified and categorised as of either foraging or early farming cultures. The Late Mesolithic phase is defined by the repetitive application of fire to the woodland to encourage a mosaic of productive vegetation regeneration patches, consistent with the promotion of Corylus and to aid hunting. In this phase, weed species including Plantago lanceolata, Rumex and Chenopodiaceae are frequent, taxa which are normally associated with the first farmers. The early Neolithic phase, including an Ulmus decline, has characteristics consistent with 'forest farming', possibly mainly for domestic livestock, with an inferred succession of tree girdling, fire-prepared cultivation, and coppice-woodland management. Such fine-resolution, potentially diagnostic land-use signatures may in future be used to recognise the cultural complexion of otherwise enigmatic woodland disturbance phases during the centuries of the Mesolithic-Neolithic transition.

A Dual-Stage Two-Phase Model of Selective Attention

ERIC Educational Resources Information Center

Hubner, Ronald; Steinhauser, Marco; Lehle, Carola

2010-01-01

The dual-stage two-phase (DSTP) model is introduced as a formal and general model of selective attention that includes both an early and a late stage of stimulus selection. Whereas at the early stage information is selected by perceptual filters whose selectivity is relatively limited, at the late stage stimuli are selected more efficiently on a…

Proteasome Inhibition Enhances the Induction and Impairs the Maintenance of Late-Phase Long-Term Potentiation

ERIC Educational Resources Information Center

Dong, Chenghai; Upadhya, Sudarshan C.; Ding, Lan; Smith, Thuy K.; Hegde, Ashok N.

2008-01-01

Protein degradation by the ubiquitin-proteasome pathway plays important roles in synaptic plasticity, but the molecular mechanisms by which proteolysis regulates synaptic strength are not well understood. We investigated the role of the proteasome in hippocampal late-phase long-term potentiation (L-LTP), a model for enduring synaptic plasticity.…

Deformation events in the Andean orogenic cycle in the Altiplano and Western Cordillera, southern Peru

NASA Astrophysics Data System (ADS)

Ellison, R. A.; Klinck, B. A.; Hawkins, M. P.

A regional mapping program associated with radiometric age dating has provided evidence of seven deformation pulses in the Andean orogenic cycle in part of southern Peru. These are the Peruvian (Late Cretaceous), Incaic (Eocene), and five Quechua phases defined as D1 to D5. The D1 phase (early Oligocene) folded molasse deposits in the Western Cordillera; the D2 phase (late Oligocene to early Miocene) folded volcanics of the Western Cordillera; the D3 phase (middle Miocene) folded the molasse deposits in the Altiplano; the D4 (late Miocene) folded lacustrine sediments in the central part of the Western Cordillera; and the D5 phase was a major gravity slide in the Altiplano. Several faults and fault zones, known as the Chupa, Calapuja, Lagunillas, and Laraqueri Faults, are identified. They form the boundaries to Paleozoic basement blocks which appear to have acted as buttresses or barriers to the penetration of some deformation events. In the case of the D5 phase, the gravity slide was preceded by uplift and tilting of a Paleozoic block.

Endothelial gaps and adherent leukocytes in allergen-induced early- and late-phase plasma leakage in rat airways.

PubMed Central

Baluk, P.; Bolton, P.; Hirata, A.; Thurston, G.; McDonald, D. M.

1998-01-01

Exposure of sensitized individuals to antigen can induce allergic responses in the respiratory tract, manifested by early and late phases of vasodilatation, plasma leakage, leukocyte influx, and bronchoconstriction. Similar responses can occur in the skin, eye, and gastrointestinal tract. The early-phase response involves mast cell mediators and the late-phase response is leukocyte dependent, but the mechanism of leakage is not understood. We sought to identify the leaky blood vessels, to determine whether these vessels contained endothelial gaps, and to analyze the relationship of the gaps to adherent leukocytes, using biotinylated lectins or silver nitrate to stain the cells in situ and Monastral blue as a tracer to quantify plasma leakage. Most of the leakage occurred in postcapillary venules (< 40-microns diameter), whereas most of the leukocyte migration (predominantly neutrophils) occurred in collecting venules. Capillaries and arterioles did not leak. Endothelial gaps were found in the leaky venules, both by silver nitrate staining and by scanning electron microscopy, and 94% of the gaps were distinct from sites of leukocyte adhesion or migration. We conclude that endothelial gaps contribute to both early and late phases of plasma leakage induced by antigen, but most leakage occurs upstream to sites of leukocyte adhesion. Images Figure 3 Figure 5 Figure 6 Figure 7 PMID:9626051

Simplified formula for mean cycle-slip time of phase-locked loops with steady-state phase error.

NASA Technical Reports Server (NTRS)

Tausworthe, R. C.

1972-01-01

Previous work shows that the mean time from lock to a slipped cycle of a phase-locked loop is given by a certain double integral. Accurate numerical evaluation of this formula for the second-order loop is extremely vexing because the difference between exponentially large quantities is involved. The presented article demonstrates a method in which a much-reduced precision program can be used to obtain the mean first-cycle slip time for a loop of arbitrary degree tracking at a specified SNR and steady-state phase error. It also presents a simple approximate formula that is asymptotically tight at higher loop SNR.

Krogh-cylinder and infinite-domain models for washout of an inert diffusible solute from tissue.

PubMed

Secomb, Timothy W

2015-01-01

Models based on the Krogh-cylinder concept are developed to analyze the washout from tissue by blood flow of an inert diffusible solute that permeates blood vessel walls. During the late phase of washout, the outflowing solute concentration decays exponentially with time. This washout decay rate is predicted for a range of conditions. A single capillary is assumed to lie on the axis of a cylindrical tissue region. In the classic "Krogh-cylinder" approach, a no-flux boundary condition is applied on the outside of the cylinder. An alternative "infinite-domain" approach is proposed that allows for solute exchange across the boundary, but with zero net exchange. Both models are analyzed, using finite-element and analytical methods. The washout decay rate depends on blood flow rate, tissue diffusivity and vessel permeability of solute, and assumed boundary conditions. At low blood flow rates, the washout rate can exceed the value for a single well-mixed compartment. The infinite-domain approach predicts slower washout decay rates than the Krogh-cylinder approach. The infinite-domain approach overcomes a significant limitation of the Krogh-cylinder approach, while retaining its simplicity. It provides a basis for developing methods to deduce transport properties of inert solutes from observations of washout decay rates. © 2014 John Wiley & Sons Ltd.

Screening of Cyanobacteria (Blue-Green algae) from Rice Paddy Soil for Antifungal Activity against Plant Pathogenic Fungi

PubMed Central

2006-01-01

Soil cyanobacteria isolated from the rice paddy fields of 10 different locations across Korea were evaluated by agar plate diffusion test for antifungal activity. Aqueous, petroleum ether, and methanol extracts from one hundred and forty two cyanobacterial strains belonging to the 14 genera were examined for antifungal properties against seven phytopathogenic fungi causing diseases in hot pepper (Capsicum annuum L). Of total cyanobacteria, nine cyanobacteria (6.34%) exhibited antifungal effects. The nine cyanobacteria selected with positive antifungal activities were two species of Oscillatoria, two of Anabaena, three of Nostoc, one of Nodularia, and one of Calothrix. Alternaria alternata and Botrytis cinerea were inhibited by nine and eight species of cyanobacteria, respectively. Rhizopus stolonifer was suppressed by only methanol extract of Nostoc commune FK-103. In particular, Nostoc commune FK-103 and Oscillatoria tenuis FK-109 showed strong antifungal activities against Phytophthora capsici. Their antifungal activity at the late exponential growth phase is related to the growth temperature and not associated with the growth parameters such as cell biomass and chlorophyll-α concentration. The high inhibition levels of antibiotics were 22.5 and 31.8 mm for N. commune FK-103 and O. tenuis FK-109, respectively. The optimal temperature for antibiotic productivity was 35℃. PMID:24039487

Compartment-specific pH monitoring in Bacillus subtilis using fluorescent sensor proteins: a tool to analyze the antibacterial effect of weak organic acids.

PubMed

van Beilen, Johan W A; Brul, Stanley

2013-01-01

The internal pH (pHi) of a living cell is one of its most important physiological parameters. To monitor the pH inside Bacillus subtilis during various stages of its life cycle, we constructed an improved version (IpHluorin) of the ratiometric, pH-sensitive fluorescent protein pHluorin by extending it at the 5' end with the first 24 bp of comGA. The new version, which showed an approximate 40% increase in fluorescence intensity, was expressed from developmental phase-specific, native promoters of B. subtilis that are specifically active during vegetative growth on glucose (PptsG) or during sporulation (PspoIIA, PspoIIID, and PsspE). Our results show strong, compartment-specific expression of IpHluorin that allowed accurate pHi measurements of live cultures during exponential growth, early and late sporulation, spore germination, and during subsequent spore outgrowth. Dormant spores were characterized by an pHi of 6.0 ± 0.3. Upon full germination the pHi rose dependent on the medium to 7.0-7.4. The presence of sorbic acid in the germination medium inhibited a rise in the intracellular pH of germinating spores and inhibited germination. Such effects were absent when acetic was added at identical concentrations.

High Milk-Clotting Activity Expressed by the Newly Isolated Paenibacillus spp. Strain BD3526.

PubMed

Hang, Feng; Liu, Peiyi; Wang, Qinbo; Han, Jin; Wu, Zhengjun; Gao, Caixia; Liu, Zhenmin; Zhang, Hao; Chen, Wei

2016-01-12

Paenibacillus spp. BD3526, a bacterium exhibiting a protein hydrolysis circle surrounded with an obvious precipitation zone on skim milk agar, was isolated from raw yak (Bos grunniens) milk collected in Tibet, China. Phylogenetic analysis based on 16S rRNA and whole genome sequence comparison indicated the isolate belong to the genus Paenibacillus. The strain BD3526 demonstrated strong ability to produce protease with milk clotting activity (MCA) in wheat bran broth. The protease with MCA was predominantly accumulated during the late-exponential phase of growth. The proteolytic activity (PA) of the BD3526 protease was 1.33-fold higher than that of the commercial R. miehei coagulant. A maximum MCA (6470 ± 281 SU mL(-1)) of the strain BD3526 was reached under optimal cultivation conditions. The protease with MCA was precipitated from the cultivated supernatant of wheat bran broth with ammonium sulfate and purified by anion-exchange chromatography. The molecular weight of the protease with MCA was determined as 35 kDa by sodium dodecyl sulfate-polyacrylamide gels electrophoresis (SDS-PAGE) and gelatin zymography. The cleavage site of the BD3526 protease with MCA in κ-casein was located at the Met106-Ala107 bond, as determined by mass spectrometry analysis.

Bacteriophage T4 Infection of Stationary Phase E. coli: Life after Log from a Phage Perspective

PubMed Central

Bryan, Daniel; El-Shibiny, Ayman; Hobbs, Zack; Porter, Jillian; Kutter, Elizabeth M.

2016-01-01

Virtually all studies of phage infections investigate bacteria growing exponentially in rich media. In nature, however, phages largely encounter non-growing cells. Bacteria entering stationary phase often activate well-studied stress defense mechanisms that drastically alter the cell, facilitating its long-term survival. An understanding of phage-host interactions in such conditions is of major importance from both an ecological and therapeutic standpoint. Here, we show that bacteriophage T4 can efficiently bind to, infect and kill E. coli in stationary phase, both in the presence and absence of a functional stationary-phase sigma factor, and explore the response of T4-infected stationary phase cells to the addition of fresh nutrients 5 or 24 h after that infection. An unexpected new mode of response has been identified. “Hibernation” mode is a persistent but reversible dormant state in which the infected cells make at least some phage enzymes, but halt phage development until appropriate nutrients become available before producing phage particles. Our evidence indicates that the block in hibernation mode occurs after the middle-mode stage of phage development; host DNA breakdown and the incorporation of the released nucleotides into phage DNA indicate that the enzymes of the nucleotide synthesizing complex, under middle-mode control, have been made and assembled into a functional state. Once fresh glucose and amino acids become available, the standard lytic infection process rapidly resumes and concentrations of up to 1011 progeny phage (an average of about 40 phage per initially present cell) are produced. All evidence is consistent with the hibernation-mode control point lying between middle mode and late mode T4 gene expression. We have also observed a “scavenger” response, where the infecting phage takes advantage of whatever few nutrients are available to produce small quantities of progeny within 2 to 5 h after infection. The scavenger response seems able to produce no more than an average of one phage per originally available cell, and few if any further progeny are produced by cells in this mode even if fresh nutrients are made available later. PMID:27660625

Analyzing signal attenuation in PFG anomalous diffusion via a non-Gaussian phase distribution approximation approach by fractional derivatives.

PubMed

Lin, Guoxing

2016-11-21

Anomalous diffusion exists widely in polymer and biological systems. Pulsed-field gradient (PFG) techniques have been increasingly used to study anomalous diffusion in nuclear magnetic resonance and magnetic resonance imaging. However, the interpretation of PFG anomalous diffusion is complicated. Moreover, the exact signal attenuation expression including the finite gradient pulse width effect has not been obtained based on fractional derivatives for PFG anomalous diffusion. In this paper, a new method, a Mainardi-Luchko-Pagnini (MLP) phase distribution approximation, is proposed to describe PFG fractional diffusion. MLP phase distribution is a non-Gaussian phase distribution. From the fractional derivative model, both the probability density function (PDF) of a spin in real space and the PDF of the spin's accumulating phase shift in virtual phase space are MLP distributions. The MLP phase distribution leads to a Mittag-Leffler function based PFG signal attenuation, which differs significantly from the exponential attenuation for normal diffusion and from the stretched exponential attenuation for fractional diffusion based on the fractal derivative model. A complete signal attenuation expression E α (-D f b α,β * ) including the finite gradient pulse width effect was obtained and it can handle all three types of PFG fractional diffusions. The result was also extended in a straightforward way to give a signal attenuation expression of fractional diffusion in PFG intramolecular multiple quantum coherence experiments, which has an n β dependence upon the order of coherence which is different from the familiar n 2 dependence in normal diffusion. The results obtained in this study are in agreement with the results from the literature. The results in this paper provide a set of new, convenient approximation formalisms to interpret complex PFG fractional diffusion experiments.

Ralstonia eutropha H16 Flagellation Changes According to Nutrient Supply and State of Poly(3-Hydroxybutyrate) Accumulation▿

PubMed Central

Raberg, Matthias; Reinecke, Frank; Reichelt, Rudolf; Malkus, Ursula; König, Simone; Pötter, Markus; Fricke, Wolfgang Florian; Pohlmann, Anne; Voigt, Birgit; Hecker, Michael; Friedrich, Bärbel; Bowien, Botho; Steinbüchel, Alexander

2008-01-01

Two-dimensional polyacrylamide gel electrophoresis (2D PAGE), in combination with matrix-assisted laser desorption ionization-time of flight analysis, and the recently revealed genome sequence of Ralstonia eutropha H16 were employed to detect and identify proteins that are differentially expressed during different phases of poly(3-hydroxybutyric acid) (PHB) metabolism. For this, a modified protein extraction protocol applicable to PHB-harboring cells was developed to enable 2D PAGE-based proteome analysis of such cells. Subsequently, samples from (i) the exponential growth phase, (ii) the stationary growth phase permissive for PHB biosynthesis, and (iii) a phase permissive for PHB mobilization were analyzed. Among several proteins exhibiting quantitative changes during the time course of a cultivation experiment, flagellin, which is the main protein of bacterial flagella, was identified. Initial investigations that report on changes of flagellation for R. eutropha were done, but 2D PAGE and electron microscopic examinations of cells revealed clear evidence that R. eutropha exhibited further significant changes in flagellation depending on the life cycle, nutritional supply, and, in particular, PHB metabolism. The results of our study suggest that R. eutropha is strongly flagellated in the exponential growth phase and loses a certain number of flagella in transition to the stationary phase. In the stationary phase under conditions permissive for PHB biosynthesis, flagellation of cells admittedly stagnated. However, under conditions permissive for intracellular PHB mobilization after a nitrogen source was added to cells that are carbon deprived but with full PHB accumulation, flagella are lost. This might be due to a degradation of flagella; at least, the cells stopped flagellin synthesis while normal degradation continued. In contrast, under nutrient limitation or the loss of phasins, cells retained their flagella. PMID:18502919

The vela pulsar: results from the first year of FERMI lat observations

DOE PAGES

Abdo, A. A.; Ackermann, M.; Ajello, M.; ...

2010-03-18

Here, we report on analysis of timing and spectroscopy of the Vela pulsar using 11 months of observations with the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope. The intrinsic brightness of Vela at GeV energies combined with the angular resolution and sensitivity of the LAT allows us to make the most detailed study to date of the energy-dependent light curves and phase-resolved spectra, using a LAT-derived timing model. The light curve consists of two peaks (P1 and P2) connected by bridge emission containing a third peak (P3). We have confirmed the strong decrease of the P1/P2 ratiomore » with increasing energy seen with EGRET and previous Fermi LAT data, and observe that P1 disappears above 20 GeV. The increase with energy of the mean phase of the P3 component can be followed with much greater detail, showing that P3 and P2 are present up to the highest energies of pulsation. We find significant pulsed emission at phases outside the main profile, indicating that magnetospheric emission exists over 80% of the pulsar period. With increased high-energy counts the phase-averaged spectrum is seen to depart from a power law with simple exponential cutoff, and is better fit with a more gradual cutoff. The spectra in fixed-count phase bins are well fit with power laws with exponential cutoffs, revealing a strong and complex phase dependence of the cutoff energy, especially in the peaks. Finally, by combining these results with predictions of the outer magnetosphere models that map emission characteristics to phase, it will be possible to probe the particle acceleration and the structure of the pulsar magnetosphere with unprecedented detail.« less

A kinetic study of blinking responses in cats

PubMed Central

Trigo, José Alberto; Roa, Laura; Gruart, Agnès; Delgado-García, José María

2003-01-01

Reflexively evoked and eye-related eyelid responses were recorded using the search coil in a magnetic field technique in alert cats. The downward phase of a blink was a large (up to 21 deg), fast (up to 2000 deg s−1) eyelid displacement in the closing direction, with an almost fixed rise time duration (15-20 ms); its maximum velocity was achieved in ≈10 ms. Upward eyelid motion was separated into two phases. The first phase consisted of a fast eyelid displacement, with a short duration (≈30 ms) and a maximum velocity up to 900 deg s−1. The second phase had an exponential-like form, lasting for 200–400 ms, and a maximum velocity ranging between 30 and 250 deg s−1. Maximum blink velocity in the downward direction was linearly related to maximum velocity of the first upward phase. The first phase in the upward direction was never observed if the eyelid stayed closed for a long period (> 50 ms) or moved slowly in the closing direction before it started to open. In these two cases, the upswing motion of the blink reflex contained only the exponential-like movement characteristic of the second upward phase, and maximum velocity in the downward direction was not related to that of the eyelid upward displacement. Mean duration of eyelid downward saccades was ≈130 ms, and their peak velocities ranged between 50 and 440 ms. A physiological model is presented explaining the active and passive forces involved in both reflex and saccadic eyelid responses. A second-order system seems to be appropriate to describe the postulated biomechanical model. PMID:12665614

Effects of Space Flight, Clinorotation, and Centrifugation on the Growth and Metabolism of Escherichia coli.

DTIC Science & Technology

1999-07-28

lag phase for Proteus vulgaris (Manko et al., 1987), E. coli, and B. subtilis (Kaceua and Todd, 1997) on orbit. However, due to a limited number of... limitations often precluded the collection of multiple bacterial counts at different times during the relatively short exponential growth phase. This...g, respectively. Because the 50 centriiiige held only 6 FPAs, the number of samples for each experiment was limited . To increase the «-value

Tyrosine decarboxylase activity of enterococci grown in media with different nutritional potential: tyramine and 2-phenylethylamine accumulation and tyrDC gene expression.

PubMed

Bargossi, Eleonora; Tabanelli, Giulia; Montanari, Chiara; Lanciotti, Rosalba; Gatto, Veronica; Gardini, Fausto; Torriani, Sandra

2015-01-01

The ability to accumulate tyramine and 2-phenylethylamine by two strains of Enterococcus faecalis and two strains Enterococcus faecium was evaluated in two cultural media added or not with tyrosine. All the enterococcal strains possessed a tyrosine decarboxylase (tyrDC) which determined tyramine accumulation in all the conditions tested, independently on the addition of high concentration of free tyrosine. Enterococci differed in rate and level of biogenic amines accumulation. E. faecalis EF37 and E. faecium FC12 produced tyramine in high amount since the exponential growth phase, while 2-phenylethylamine was accumulated when tyrosine was depleted. E. faecium FC12 and E. faecalis ATCC 29212 showed a slower tyraminogenic activity which took place mainly in the stationary phase up to 72 h of incubation. Moreover, E. faecalis ATCC 29212 produced 2-phenylethylamine only in the media without tyrosine added. In BHI added or not with tyrosine the tyrDC gene expression level differed considerably depending on the strains and the growth phase. In particular, the tyrDC gene expression was high during the exponential phase in rich medium for all the strains and subsequently decreased except for E. faecium FC12. Even if tyrDC presence is common among enterococci, this study underlines the extremely variable decarboxylating potential of strains belonging to the same species, suggesting strain-dependent implications in food safety.

Analysis of compound action potentials elicited with specific current stimulating pulses in an isolated rat sciatic nerve.

PubMed

Žužek, Monika C; Rozman, Janez; Pečlin, Polona; Vrecl, Milka; Frangež, Robert

2017-02-01

The ability to selectively stimulate Aα, Aβ-fibers and Aδ-fibers in an isolated rat sciatic nerve (SNR) was assessed. The stimulus used was a current, biphasic pulse with a quasitrapezoidal cathodic phase and rectangular anodic phase where parameters were systematically varied: intensity of the cathodic phase (ic); width of the cathodic phase (tc); width of the cathodic exponential decay (texp) and time constant of the exponential decay (τexp). A SNR was stimulated using a pair of hook electrodes while conduction velocity (CV) and compound action potentials (CAP) were measured at two sites along the SNR using another two pairs of electrodes. Results showed that the highest CAP1 (8.5-9 mV), shall be expected when parameters of the stimulus were within the following range: ic=3.8-4 mA, tc=350-400 μs and texp=330-440 μs. Results also showed that with ascending tc and texp, CV of the corresponding superficial region of the SNR was reduced in both, conduction velocity of CAP1 and conduction velocity of CAP2. It was concluded that action potentials (APs) were activated in the Aβ-fibers and Aδ-fibers along with a slight AP inhibition in the Aβ-fibers. The obtained results, could serve as a tool for developing multi-electrode systems that potentially enable fiber-type selective stimulation of nerve fibers.

Effect of Medium pH on Rhodosporidium toruloides NCYC 921 Carotenoid and Lipid Production Evaluated by Flow Cytometry.

PubMed

Dias, Carla; Silva, Corália; Freitas, Claudia; Reis, Alberto; da Silva, Teresa Lopes

2016-07-01

The effect of the culture medium pH (3.5-6.0) on the carotenoid and lipid (as fatty acids) production by the yeast Rhodosporidium toruloides NCYC 921 was studied. Flow cytometry was used to evaluate the yeast's physiological response to different culture medium pH values. The yeast biomass concentration and lipid content were maxima at pH 4.0 (5.90 g/L and 21.85 % w/w, respectively), while the maximum carotenoid content (63.37 μg/g) was obtained at pH 5.0. At the exponential phase, the yeast cell size and internal complexity were similar, at different medium pH. At the stationary phase, the yeast cell size and internal complexity decreased as the medium pH increased. At the exponential phase, the proportion of cells with polarized membranes was always high (>80 %) but at the stationary phase, the proportion of yeast cells with depolarized membranes was dominant (>65 %) and increased with the medium pH increase. The results here reported may contribute for yeast bioprocesses optimization. For the first time, multiparameter flow cytometry was used to evaluate the impact of medium pH changes on the yeast cell physiological status, specifically on the yeast membrane potential, membrane integrity, cell size and internal complexity.

Stochastical analysis of surfactant-enhanced remediation of denser-than-water nonaqueous phase liquid (DNAPL)-contaminated soils.

PubMed

Zhang, Renduo; Wood, A Lynn; Enfield, Carl G; Jeong, Seung-Woo

2003-01-01

Stochastical analysis was performed to assess the effect of soil spatial variability and heterogeneity on the recovery of denser-than-water nonaqueous phase liquids (DNAPL) during the process of surfactant-enhanced remediation. UTCHEM, a three-dimensional, multicomponent, multiphase, compositional model, was used to simulate water flow and chemical transport processes in heterogeneous soils. Soil spatial variability and heterogeneity were accounted for by considering the soil permeability as a spatial random variable and a geostatistical method was used to generate random distributions of the permeability. The randomly generated permeability fields were incorporated into UTCHEM to simulate DNAPL transport in heterogeneous media and stochastical analysis was conducted based on the simulated results. From the analysis, an exponential relationship between average DNAPL recovery and soil heterogeneity (defined as the standard deviation of log of permeability) was established with a coefficient of determination (r2) of 0.991, which indicated that DNAPL recovery decreased exponentially with increasing soil heterogeneity. Temporal and spatial distributions of relative saturations in the water phase, DNAPL, and microemulsion in heterogeneous soils were compared with those in homogeneous soils and related to soil heterogeneity. Cleanup time and uncertainty to determine DNAPL distributions in heterogeneous soils were also quantified. The study would provide useful information to design strategies for the characterization and remediation of nonaqueous phase liquid-contaminated soils with spatial variability and heterogeneity.

Mechanisms underlying hemodynamic and neuroendocrine stress reactivity at different phases of the menstrual cycle

PubMed Central

Gordon, Jennifer L.; Girdler, Susan S.

2014-01-01

This study examined the association of menstrual cycle phase with stress reactivity as well as the hormonal and neuroendocrine mechanisms contributing to cycle effects. Fifty-seven women underwent a modified Trier Social Stress Test (TSST) during the early follicular, late follicular and luteal phases of the menstrual cycle. Greater increases in cardiac index (CI) and greater decreases in vascular resistance index (VRI) during speech were observed in the luteal phase relative to other phases, while greater increases in epinephrine (EPI) was observed during the late follicular and luteal phases compared to the early follicular phase. Luteal phase estradiol predicted luteal EPI reactivity but not CI or VRI reactivity while luteal phase EPI reactivity predicted luteal phase CI and VRI reactivity. Thus, cycle-related changes in EPI reactivity may be a stronger determinant of cycle effects on hemodynamic reactivity than sex hormones per se. PMID:24397365

Association of a trait-like bias towards the perception of negative subjective life events with risk of developing premenstrual symptoms.

PubMed

Gonda, Xenia; Fountoulakis, Konstantinos N; Csukly, Gabor; Telek, Tamas; Pap, Dorottya; Rihmer, Zoltan; Bagdy, Gyorgy

2010-04-16

Premenstrual symptoms affect the majority of healthy women. Premenstrual symptomatology has earlier been linked to stress and a state-like alteration in the perception of life events in the late-luteal phase of the menstrual cycle. We hypothesised that there is also a trait-like negative bias in the perception of life events evident throughout the whole cycle which is associated with the likelihood to manifest more marked symptoms in the late-luteal phase of the cycle. 88 healthy women completed the PRISM calendar for three consecutive cycles and the Objective and Subjective Event Checklist during the follicular phase of the first cycle. Association between PRISM score change from the follicular through the late-luteal phase and life event variables was investigated by Generalized Linear Model Analysis (GENMOD). The PRISM score change showed a significant negative association with the ratio of positive subjective life events and a significant positive association with the ratio of negative subjective life events. There were no significant results in case of the objective life events. Our results indicate that women manifesting a more marked increase of symptoms from the late follicular through the late-luteal phase of the menstrual cycle are more likely to notice negative subjective life events and less likely to notice positive subjective life events. This suggest a trait-like negative bias in the perception of life events present throughout the whole reproductive cycle which may play an important role in the emergence of premenstrual symptoms. Copyright 2010 Elsevier Inc. All rights reserved.

Positive force feedback in human walking

PubMed Central

Grey, Michael J; Nielsen, Jens Bo; Mazzaro, Nazarena; Sinkjær, Thomas

2007-01-01

The objective of this study was to determine if load receptors contribute to the afferent-mediated enhancement of ankle extensor muscle activity during the late stance phase of the step cycle. Plantar flexion perturbations were presented in late stance while able-bodied human subjects walked on a treadmill that was declined by 4%, inclined by 4% or held level. The plantar flexion perturbation produced a transient, but marked, presumably spinally mediated decrease in soleus EMG that varied directly with the treadmill inclination. Similarly, the magnitude of the control step soleus EMG and Achilles' tendon force also varied directly with the treadmill inclination. In contrast, the ankle angular displacement and velocity were inversely related to the treadmill inclination. These results suggest that Golgi tendon organ feedback, via the group Ib pathway, is reduced when the muscle–tendon complex is unloaded by a rapid plantar flexion perturbation in late stance phase. The changes in the unload response with treadmill inclination suggest that the late stance phase soleus activity may be enhanced by force feedback. PMID:17331984

Exploiting fast detectors to enter a new dimension in room-temperature crystallography

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

Owen, Robin L., E-mail: robin.owen@diamond.ac.uk; Paterson, Neil; Axford, Danny

2014-05-01

A departure from a linear or an exponential decay in the diffracting power of macromolecular crystals is observed and accounted for through consideration of a multi-state sequential model. A departure from a linear or an exponential intensity decay in the diffracting power of protein crystals as a function of absorbed dose is reported. The observation of a lag phase raises the possibility of collecting significantly more data from crystals held at room temperature before an intolerable intensity decay is reached. A simple model accounting for the form of the intensity decay is reintroduced and is applied for the first timemore » to high frame-rate room-temperature data collection.« less

Brain responses to food images during the early and late follicular phase of the menstrual cycle in healthy young women: relation to fasting and feeding1234

PubMed Central

Ziemke, Florencia; Magkos, Faidon; Barrios, Fernando A; Brinkoetter, Mary; Boyd, Ingrid; Rifkin-Graboi, Anne; Yannakoulia, Mary; Rojas, Rafael; Pascual-Leone, Alvaro; Mantzoros, Christos S

2011-01-01

Background: Food intake fluctuates throughout the menstrual cycle; it is greater during the early follicular and luteal phases than in the late follicular (periovulatory) phase. Ovarian steroids can influence brain areas that process food-related information, but the specific contribution of individual hormones and the importance of the prandial state remain unknown. Objective: The objective was to examine whether brain activation during food visualization is affected by changes in estradiol concentration in the fasted and fed conditions. Design: Nine eumenorrheic, lean young women [mean (±SD) age: 26.2 ± 3.2 y; body mass index (in kg/m2): 22.4 ± 1.2] completed 2 visits, one in the early (low estradiol) and one in the late (high estradiol) follicular phase of their menstrual cycle. At each visit, subjects underwent functional magnetic resonance imaging while they viewed food and nonfood images, before and after a standardized meal. Region-of-interest analysis was used to examine the effect of follicular phase and prandial state on brain activation (food > nonfood contrast) and its association with estradiol concentration. Results: Differences were identified in the inferior frontal and fusiform gyri. In these areas, visualization of food elicited greater activation in the fed state than during fasting but only in the late follicular phase, when estradiol concentration was high. The change in estradiol concentration across the follicular phase (late minus early) was inversely correlated with the change in fusiform gyrus activation in the fasted state but not in the fed state. Conclusion: Our findings suggest that estradiol may reduce food intake by decreasing sensitivity to food cues in the ventral visual pathway under conditions of energy deprivation. This trial was registered at clinicaltrials.gov as NCT00130117. PMID:21593494

HSP70.1 AND -70.3 ARE REQUIRED FOR LATE-PHASE PROTECTION INDUCED BY ISCHEMIC PRECONDITIONING OF MOUSE HEARTS

EPA Science Inventory

Heat-Shock Proteins 70.1 and 70.3 Are Required for Late-phase Protection
Induced by Ischemic Preconditioning of the Mouse Heart
Craig R. Hampton 1 , Akira Shimamoto 1 , Christine L. Rothnie 1 , Jeaneatte Griscavage-Ennis 1 ,
Albert Chong 1 , David J. Dix 2 , Edward D. Ve...

Food cravings and food cue responding across the menstrual cycle in a non-eating disordered sample.

PubMed

McVay, Megan Apperson; Copeland, Amy L; Newman, Hannah S; Geiselman, Paula J

2012-10-01

The study aim was to examine changes in food cue-elicited cravings and the macronutrient content of craved foods across menstrual cycle phases in a non-eating disordered sample. Thirty-five college females attended laboratory sessions in the late follicular and late luteal phases. In each session they completed a measure of state food craving before and after exposure to preferred, high fat/high sugar chocolate candy. Candy consumption following cue exposure was measured during an ad libitum "taste test." Additionally, participants rated their desire to eat foods differing systematically and significantly in macronutrient content. Ovulation was confirmed with luteinizing hormone detection kits. Results show that whereas the food cue increased cravings, this effect did not differ between cycle phases examined. The macronutrient content of foods desired also did not differ significantly between cycle phases, however, a non-significant trend suggested that high fat/high complex carbohydrate and low fat/high protein foods were more strongly desired in the late luteal phase. Amount of chocolate candy eaten did not differ between cycle phases. These results suggest that cravings for high fat/high sugar foods do not differ between menstrual cycle phases examined, whereas cravings for other foods may fluctuate across cycle phases in non-eating disordered women. Copyright © 2012 Elsevier Ltd. All rights reserved.

Context and explicit threat cue modulation of the startle reflex: Preliminary evidence of distinctions between adolescents with principal fear disorders versus distress disorders

PubMed Central

Waters, Allison M.; Nazarian, Maria; Mineka, Susan; Zinbarg, Richard E.; Griffith, James W.; Naliboff, Bruce; Ornitz, Edward M.; Craske, Michelle G.

2014-01-01

Anxiety and depression are prevalent, impairing disorders. High comorbidity has raised questions about how to define and classify them. Structural models emphasise distinctions between “fear” and “distress” disorders while other initiatives propose they be defined by neurobiological indicators that cut across disorders. This study examined startle reflex (SR) modulation in adolescents with principal fear disorders (specific phobia; social phobia) (n = 20), distress disorders (unipolar depressive disorders, dysthymia, generalized anxiety disorder; post-traumatic stress disorder) (n = 9), and controls (n = 29) during (a) baseline conditions, (b) threat context conditions (presence of contraction pads over the biceps muscle), and (c) an explicit threat cue paradigm involving phases that signalled safety from aversive stimuli (early and late stages of safe phases; early stages of danger phases) and phases that signalled immediate danger of an aversive stimulus (late stages of danger phases). Adolescents with principal fear disorders showed larger SRs than other groups throughout safe phases and early stages of danger phases. SRs did not differ between groups during late danger phases. Adolescents with principal distress disorders showed attenuated SRs during baseline and context conditions compared to other groups. Preliminary findings support initiatives to redefine emotional disorders based on neurobiological functioning. PMID:24679992

Simultaneous Gaussian and exponential inversion for improved analysis of shales by NMR relaxometry

USGS Publications Warehouse

Washburn, Kathryn E.; Anderssen, Endre; Vogt, Sarah J.; Seymour, Joseph D.; Birdwell, Justin E.; Kirkland, Catherine M.; Codd, Sarah L.

2014-01-01

Nuclear magnetic resonance (NMR) relaxometry is commonly used to provide lithology-independent porosity and pore-size estimates for petroleum resource evaluation based on fluid-phase signals. However in shales, substantial hydrogen content is associated with solid and fluid signals and both may be detected. Depending on the motional regime, the signal from the solids may be best described using either exponential or Gaussian decay functions. When the inverse Laplace transform, the standard method for analysis of NMR relaxometry results, is applied to data containing Gaussian decays, this can lead to physically unrealistic responses such as signal or porosity overcall and relaxation times that are too short to be determined using the applied instrument settings. We apply a new simultaneous Gaussian-Exponential (SGE) inversion method to simulated data and measured results obtained on a variety of oil shale samples. The SGE inversion produces more physically realistic results than the inverse Laplace transform and displays more consistent relaxation behavior at high magnetic field strengths. Residuals for the SGE inversion are consistently lower than for the inverse Laplace method and signal overcall at short T2 times is mitigated. Beyond geological samples, the method can also be applied in other fields where the sample relaxation consists of both Gaussian and exponential decays, for example in material, medical and food sciences.

Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise.

PubMed

Youngstedt, Shawn D; Kline, Christopher E; Elliott, Jeffrey A; Zielinski, Mark R; Devlin, Tina M; Moore, Teresa A

2016-02-26

Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210-2340 h, (2) treadmill exercise alone from 2210-2340 h, or (3) bright light (2210-2340 h) followed by exercise from 0410-0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect.

The Next Computer Revolution.

ERIC Educational Resources Information Center

Peled, Abraham

1987-01-01

Discusses some of the future trends in the use of the computer in our society, suggesting that computing is now entering a new phase in which it will grow exponentially more powerful, flexible, and sophisticated in the next decade. Describes some of the latest breakthroughs in computer hardware and software technology. (TW)

Therapist adherence is associated with outcome in cognitive-behavioral therapy for bulimia nervosa.

PubMed

Folke, Sofie; Daniel, Sarah I F; Gondan, Matthias; Lunn, Susanne; Tækker, Louise; Poulsen, Stig

2017-06-01

Studies of therapist adherence in relation to treatment outcome have produced mixed results. The aim of the present study was to investigate change in therapist adherence to cognitive-behavioral therapy (CBT) for bulimia nervosa over time, and to investigate the relationship between adherence and client outcome in early, middle, and late phases of treatment. Thirty-six clients received the focused form of "enhanced" CBT (CBT-E) for bulimia nervosa. Trained observers rated audiotapes of 92 full-length therapy sessions from early (Session 3), middle (Session 11), and late phases (Session 20) of treatment using the Cognitive-Behavioral Therapy Treatment Protocol Adherence Scale. Change in adherence across the 3 treatment phases was examined using multilevel analysis. The relationship between early, middle, and late adherence levels and end-of-treatment binging frequency was examined using multilevel Poisson regression analysis. Adherence decreased significantly over the course of treatment. Higher levels of therapist adherence in early and middle phases of treatment were associated with reduced binging frequency, whereas higher levels of adherence measured late in treatment was not. Results indicate that therapists' adherence to the CBT-E treatment protocol decreases over time and that high levels of protocol adherence in early and middle phases of treatment are more important for positive client outcomes than high levels of adherence in the end of treatment. (PsycINFO Database Record (c) 2017 APA, all rights reserved).

Inter-decadal change in potential predictability of the East Asian summer monsoon

NASA Astrophysics Data System (ADS)

Li, Jiao; Ding, Ruiqiang; Wu, Zhiwei; Zhong, Quanjia; Li, Baosheng; Li, Jianping

2018-05-01

The significant inter-decadal change in potential predictability of the East Asian summer monsoon (EASM) has been investigated using the signal-to-noise ratio method. The relatively low potential predictability appears from the early 1950s through the late 1970s and during the early 2000s, whereas the potential predictability is relatively high from the early 1980s through the late 1990s. The inter-decadal change in potential predictability of the EASM can be attributed mainly to variations in the external signal of the EASM. The latter is mostly caused by the El Niño-Southern Oscillation (ENSO) inter-decadal variability. As a major external signal of the EASM, the ENSO inter-decadal variability experiences phase transitions from negative to positive phases in the late 1970s, and to negative phases in the late 1990s. Additionally, ENSO is generally strong (weak) during a positive (negative) phase of the ENSO inter-decadal variability. The strong ENSO is expected to have a greater influence on the EASM, and vice versa. As a result, the potential predictability of the EASM tends to be high (low) during a positive (negative) phase of the ENSO inter-decadal variability. Furthermore, a suite of Pacific Pacemaker experiments suggests that the ENSO inter-decadal variability may be a key pacemaker of the inter-decadal change in potential predictability of the EASM.

MCM-BP regulates unloading of the MCM2–7 helicase in late S phase

PubMed Central

Nishiyama, Atsuya; Frappier, Lori; Méchali, Marcel

2011-01-01

Origins of DNA replication are licensed by recruiting MCM2–7 to assemble the prereplicative complex (pre-RC). How MCM2–7 is inactivated or removed from chromatin at the end of S phase is still unclear. Here, we show that MCM-BP can disassemble the MCM2–7 complex and might function as an unloader of MCM2–7 from chromatin. In Xenopus egg extracts, MCM-BP exists in a stable complex with MCM7, but is not associated with the MCM2–7 hexameric complex. MCM-BP accumulates in nuclei in late S phase, well after the loading of MCM2–7 onto chromatin. MCM-BP immunodepletion in Xenopus egg extracts inhibits replication-dependent MCM dissociation without affecting pre-RC formation and DNA replication. When excess MCM-BP is incubated with Xenopus egg extracts or immunopurified MCM2–7, it binds to MCM proteins and promotes disassembly of the MCM2–7 complex. Recombinant MCM-BP also releases MCM2–7 from isolated late-S-phase chromatin, but this activity is abolished when DNA replication is blocked. MCM-BP silencing in human cells also delays MCM dissociation in late S phase. We propose that MCM-BP plays a key role in the mechanism by which pre-RC is cleared from replicated DNA in vertebrate cells. PMID:21196493

The tectonometamorphic evolution of the Apuseni Mountains (Romania): Geodynamic constraints for the evolution of the Alps-Carpathians-Dinaride system of orogens

NASA Astrophysics Data System (ADS)

Reiser, Martin; Schuster, Ralf; Fügenschuh, Bernhard

2015-04-01

New structural, thermobarometric and geochronological data allow integrating kinematics, timing and intensity of tectonic phases into a geodynamic model of the Apuseni Mountain, which provides new constraints for the evolution of the Alps-Carpathians-Dinaride system of orogens. Strong differences in terms of deformation directions between Early and Late Cretaceous events provide new constraints on the regional geodynamic evolution during the Cretaceous. Geochronological and structural data evidence a Late Jurassic emplacement of the South Apuseni Ophiolites on top of the Biharia Nappe System (Dacia Mega-Unit), situated in an external position at the European margin. Following the emplacement of the ophiolites, three compressive deformation phases affected the Apuseni Mountains during Alpine orogeny: a) NE-directed in-sequence nappe stacking and regional metamorphic overprinting under amphibolite-facies conditions during the Early Cretaceous ("Austrian Phase"), b) NW-directed thrusting and folding, associated with greenschist-facies overprinting, during the early Late Cretaceous ("Turonian Phase") and c) E-W internal folding together with brittle thrusting during the latest Cretaceous ("Laramian Phase"). Major tectonic unroofing and exhumation at the transition from Early to Late Cretaceous times is documented through new Sm-Nd Grt, Ar-Ar Ms and Rb-Sr Bt ages from the study area and resulted in a complex thermal structure with strong lateral and vertical thermal gradients. Nappe stacking and medium-grade metamorphic overprinting during the Early Cretaceous exhibits striking parallels between the evolution of the Tisza-Dacia Mega-Units and the Austroalpine Nappes (ALCAPA Mega-Unit) and evidences a close connection. However, Late Cretaceous tectonic events in the study area exhibit strong similarities with the Dinarides. Thus, the Apuseni Mountains represent the "missing link" between the Early Cretaceous Meliata subduction (associated with obduction of ophiolites) and the Neotethys subduction during Late Cretaceous times.

Impact of adaptation currents on synchronization of coupled exponential integrate-and-fire neurons.

PubMed

Ladenbauer, Josef; Augustin, Moritz; Shiau, LieJune; Obermayer, Klaus

2012-01-01

The ability of spiking neurons to synchronize their activity in a network depends on the response behavior of these neurons as quantified by the phase response curve (PRC) and on coupling properties. The PRC characterizes the effects of transient inputs on spike timing and can be measured experimentally. Here we use the adaptive exponential integrate-and-fire (aEIF) neuron model to determine how subthreshold and spike-triggered slow adaptation currents shape the PRC. Based on that, we predict how synchrony and phase locked states of coupled neurons change in presence of synaptic delays and unequal coupling strengths. We find that increased subthreshold adaptation currents cause a transition of the PRC from only phase advances to phase advances and delays in response to excitatory perturbations. Increased spike-triggered adaptation currents on the other hand predominantly skew the PRC to the right. Both adaptation induced changes of the PRC are modulated by spike frequency, being more prominent at lower frequencies. Applying phase reduction theory, we show that subthreshold adaptation stabilizes synchrony for pairs of coupled excitatory neurons, while spike-triggered adaptation causes locking with a small phase difference, as long as synaptic heterogeneities are negligible. For inhibitory pairs synchrony is stable and robust against conduction delays, and adaptation can mediate bistability of in-phase and anti-phase locking. We further demonstrate that stable synchrony and bistable in/anti-phase locking of pairs carry over to synchronization and clustering of larger networks. The effects of adaptation in aEIF neurons on PRCs and network dynamics qualitatively reflect those of biophysical adaptation currents in detailed Hodgkin-Huxley-based neurons, which underscores the utility of the aEIF model for investigating the dynamical behavior of networks. Our results suggest neuronal spike frequency adaptation as a mechanism synchronizing low frequency oscillations in local excitatory networks, but indicate that inhibition rather than excitation generates coherent rhythms at higher frequencies.

Yeast Pah1p Phosphatidate Phosphatase Is Regulated by Proteasome-mediated Degradation*

PubMed Central

Pascual, Florencia; Hsieh, Lu-Sheng; Soto-Cardalda, Aníbal; Carman, George M.

2014-01-01

Yeast PAH1-encoded phosphatidate phosphatase is the enzyme responsible for the production of the diacylglycerol used for the synthesis of triacylglycerol that accumulates in the stationary phase of growth. Paradoxically, the growth phase-mediated inductions of PAH1 and phosphatidate phosphatase activity do not correlate with the amount of Pah1p; enzyme abundance declined in a growth phase-dependent manner. Pah1p from exponential phase cells was a relatively stable protein, and its abundance was not affected by incubation with an extract from stationary phase cells. Recombinant Pah1p was degraded upon incubation with the 100,000 × g pellet fraction of stationary phase cells, although the enzyme was stable when incubated with the same fraction of exponential phase cells. MG132, an inhibitor of proteasome function, prevented degradation of the recombinant enzyme. Endogenously expressed and plasmid-mediated overexpressed levels of Pah1p were more abundant in the stationary phase of cells treated with MG132. Pah1p was stabilized in mutants with impaired proteasome (rpn4Δ, blm10Δ, ump1Δ, and pre1 pre2) and ubiquitination (hrd1Δ, ubc4Δ, ubc7Δ, ubc8Δ, and doa4Δ) functions. The pre1 pre2 mutations that eliminate nearly all chymotrypsin-like activity of the 20 S proteasome had the greatest stabilizing effect on enzyme levels. Taken together, these results supported the conclusion that Pah1p is subject to proteasome-mediated degradation in the stationary phase. That Pah1p abundance was stabilized in pah1Δ mutant cells expressing catalytically inactive forms of Pah1p and dgk1Δ mutant cells with induced expression of DGK1-encoded diacylglycerol kinase indicated that alteration in phosphatidate and/or diacylglycerol levels might be the signal that triggers Pah1p degradation. PMID:24563465

Impact of Adaptation Currents on Synchronization of Coupled Exponential Integrate-and-Fire Neurons

PubMed Central

Ladenbauer, Josef; Augustin, Moritz; Shiau, LieJune; Obermayer, Klaus

2012-01-01

The ability of spiking neurons to synchronize their activity in a network depends on the response behavior of these neurons as quantified by the phase response curve (PRC) and on coupling properties. The PRC characterizes the effects of transient inputs on spike timing and can be measured experimentally. Here we use the adaptive exponential integrate-and-fire (aEIF) neuron model to determine how subthreshold and spike-triggered slow adaptation currents shape the PRC. Based on that, we predict how synchrony and phase locked states of coupled neurons change in presence of synaptic delays and unequal coupling strengths. We find that increased subthreshold adaptation currents cause a transition of the PRC from only phase advances to phase advances and delays in response to excitatory perturbations. Increased spike-triggered adaptation currents on the other hand predominantly skew the PRC to the right. Both adaptation induced changes of the PRC are modulated by spike frequency, being more prominent at lower frequencies. Applying phase reduction theory, we show that subthreshold adaptation stabilizes synchrony for pairs of coupled excitatory neurons, while spike-triggered adaptation causes locking with a small phase difference, as long as synaptic heterogeneities are negligible. For inhibitory pairs synchrony is stable and robust against conduction delays, and adaptation can mediate bistability of in-phase and anti-phase locking. We further demonstrate that stable synchrony and bistable in/anti-phase locking of pairs carry over to synchronization and clustering of larger networks. The effects of adaptation in aEIF neurons on PRCs and network dynamics qualitatively reflect those of biophysical adaptation currents in detailed Hodgkin-Huxley-based neurons, which underscores the utility of the aEIF model for investigating the dynamical behavior of networks. Our results suggest neuronal spike frequency adaptation as a mechanism synchronizing low frequency oscillations in local excitatory networks, but indicate that inhibition rather than excitation generates coherent rhythms at higher frequencies. PMID:22511861

Charge Exchange Contribution to the Decay of the Ring Current, Measured by Energetic Neutral Atoms (ENAs)

NASA Technical Reports Server (NTRS)

Jorgensen, A. M.; Henderson, M. G.; Roelof, E. C.; Reeves, G. D.; Spence, H. E.

2001-01-01

In this paper we calculate the contribution of charge exchange to the decay of the ring current. Past works have suggested that charge exchange of ring current protons is primarily responsible for the decay of the ring current during the late recovery phase, but there is still much debate about the fast decay of the early recovery phase. We use energetic neutral atom (ENA) measurements from Polar to calculate the total ENA energy escape. To get the total ENA escape we apply a forward modeling technique, and to estimate the total ring current energy escape we use the Dessler-Parker-Sckopke relationship. We find that during the late recovery phase of the March 10, 1998 storm ENAs with energies greater than 17.5 keV can account for 75% of the estimated energy loss from the ring current. During the fast recovery the measured ENAs can only account for a small portion of the total energy loss. We also find that the lifetime of the trapped ions is significantly shorter during the fast recovery phase than during the late recovery phase, suggesting that different processes are operating during the two phases.

On the Existence of Non-Oscillatory Phase Functions for Second Order Ordinary Differential Equations in the High-Frequency Regime

DTIC Science & Technology

2014-08-04

Chebyshev coefficients of both r and q decay exponentially, although those of r decay at a slightly slower rate. 10.2. Evaluation of Legendre polynomials ...In this experiment, we compare the cost of evaluating Legendre polynomials of large order using the standard recurrence relation with the cost of...doing so with a nonoscillatory phase function. For any integer n ě 0, the Legendre polynomial Pnpxq of order n is a solution of the second order

gamma-Glutamyltranspeptidase from Escherichia coli K-12: formation and localization.

PubMed

Suzuki, H; Kumagai, H; Tochikura, T

1986-12-01

Escherichia coli cells showed maximum activity of gamma-glutamyltranspeptidase (EC 2.3.2.2) when they were grown at 20 degrees C, 14% of maximum activity at 37 degrees C, and none at 43 degrees C. The enzyme activity of intact cells grown at 20 degrees C was stably maintained after the temperature was changed to 45 degrees C. The activity increased during the exponential phase, and maximum activity was found at stationary phase. Its intracellular localization in the periplasmic space was confirmed.

The effect of learning on feedback-related potentials in adolescents with dyslexia: an EEG-ERP study.

PubMed

Kraus, Dror; Horowitz-Kraus, Tzipi

2014-01-01

Individuals with dyslexia exhibit associated learning deficits and impaired executive functions. The Wisconsin Card Sorting Test (WCST) is a learning-based task that relies heavily on executive functioning, in particular, attention shift and working memory. Performance during early and late phases of a series within the task represents learning and implementation of a newly learned rule. Here, we aimed to examine two event-related potentials associated with learning, feedback-related negativity (FRN)-P300 complex, in individuals with dyslexia performing the WCST. Adolescents with dyslexia and age-matched typical readers performed the Madrid card sorting test (MCST), a computerized version of the WCST. Task performance, reading measures, and cognitive measures were collected. FRN and the P300 complex were acquired using the event-related potentials methodology and were compared in early vs late errors within a series. While performing the MCST, both groups showed a significant reduction in average reaction times and a trend toward decreased error rates. Typical readers performed consistently better than individuals with dyslexia. FRN amplitudes in early phases were significantly smaller in dyslexic readers, but were essentially equivalent to typical readers in the late phase. P300 amplitudes were initially smaller among readers with dyslexia and tended to decrease further in late phases. Differences in FRN amplitudes for early vs late phases were positively correlated with those of P300 amplitudes in the entire sample. Individuals with dyslexia demonstrate a behavioral and electrophysiological change within single series of the MCST. However, learning patterns seem to differ between individuals with dyslexia and typical readers. We attribute these differences to the lower baseline performance of individuals with dyslexia. We suggest that these changes represent a fast compensatory mechanism, demonstrating the importance of learning strategies on reading among individuals with dyslexia.

Peptidase activity in various species of dairy thermophilic lactobacilli.

PubMed

Gatti, M; Fornasari, M E; Lazzi, C; Mucchetti, G; Neviani, E

2004-01-01

The aim of the present work was to evaluate the enzymatic potential manifested by aminopeptidase activity of different thermophilic Lactobacillus biotypes and to measure the influence of cell growth phase on enzyme expression. The activities were evaluated by the hydrolysis of beta-naphthylamide substrates for both whole and mechanically disrupted cells of L. helveticus, L. delbrueckii subsp. bulgaricus and L. delbrueckii subsp. lactis strains, collected from both the exponential and the stationary growth phase. In general, activities were higher for cells in the exponential rather than in the stationary phase and the disrupted cells showed higher activities than the whole cells. The highest activity expressed by all strains corresponded to X-prolyl-dipeptidyl aminopeptidase while a moderate activity was observed towards Arg-betaNa, Lys-betaNa and Leu-betaNa. The lowest activity was observed for Pro-betaNa. It may be inferred that the cell structure and the cell physiology are crucial to define the level of efficiency of expression for aminopeptidase activity. The two species may be characterized by a different enzymatic system that hydrolyses N-terminal leucine. The differences of peptidase activities in L. helveticus and L. delbrueckii species acquires an importance to comprehend their role in the biochemical events occurring in cheese ripening.

Hard diffraction and deep inelastic scattering

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

Bjorken, J.D.

1994-04-01

Since the advent of hard-collision physics, the study of diffractive processes - shadow physics - has been less prominent than before. However, there is now a renewed interest in the subject, especially in that aspect which synthesizes the short-distance, hard-collision phenomena with the classical physics of large rapidity-gaps. This is especially stimulated by the recent data on deep-inelastic scattering from HERA, as well as the theoretical work which relates to it. The word diffraction is sometimes used by high-energy physicists in a loose way. The author defines this term to mean: A diffractive process occurs if and only if theremore » is a large rapidity gap in the produced-particle phase space which is not exponentially suppressed. Here a rapidity gap means essentially no hadrons produced into the rapidity gap (which operates in the {open_quotes}lego{close_quotes} phase-space of pseudo-rapidity and azimuthal angle). And non-exponential suppression implies that the cross-section for creating a gap with width {Delta}{eta} does not have a power-law decrease with increasing subenergy s=e{sup {Delta}{eta}}, but behaves at most like some power of pseudorapidity {Delta}{eta}{approx}log(s). The term hard diffraction shall simply refer to those diffractive process which have jets in the final-state phase-space.« less

The fate of mitochondrial loci in rho minus mutants induced by ultraviolet irradiation of Saccharomyces cerevisiae: effects of different post-irradiation treatments.

PubMed

Heude, M; Moustacchi, E

1979-09-01

Three main features regarding the loss of mitochondrial genetic markers among rho- mutants induced by ultraviolet irradiation are reported: (a) the frequency of loss of six loci examined increases with UV dose; (b) preferential loss of one region of the mitochondrial genome observed in spontaneous rho- mutants is enhanced by UV; and (c) the loss of each marker results from large deletions. Marker loss in rho- mutants was also investigated under conditions that modulate rho- induction. Liquid holding of irradiated exponential or stationary phase cells, as well as a split-dose regime applied to stationary phase cells, results in rho- mutants in which the loss of markers is correlated with rho- induction: the more sensitive the cells are to rho- induction, the more frequent are the marker losses among rho- clones derived from these cells. This correlation is not found in exponential-phase cells submitted to a split-dose treatment, suggesting that a different mechanism is involved in the latter case. It is known that UV-induced pyrimidine dimers are not excised in a controlled manner in mitochondrial DNA. However, our studies indicate that an accurate repair mechanism (of the recombinational type ?) can lead to the restoration of mitochondrial genetic information in growing cells.

Inhibition of Late and Early Phases of Cancer Metastasis by the NF-κB Inhibitor DHMEQ Derived from Microbial Bioactive Metabolite Epoxyquinomicin: A Review.

PubMed

Lin, Yinzhi; Ukaji, Tamami; Koide, Naoki; Umezawa, Kazuo

2018-03-03

We previously designed and synthesized dehydroxyepoxyquinomicin (DHMEQ) as an inhibitor of NF-κB based on the structure of microbial secondary metabolite epoxyquinomicin C. DHMEQ showed anti-inflammatory and anticancer activity in various in vivo disease models without toxicity. On the other hand, the process of cancer metastasis consists of cell detachment from the primary tumor, invasion, transportation by blood or lymphatic vessels, invasion, attachment, and formation of secondary tumor. Cell detachment from the primary tumor and subsequent invasion are considered to be early phases of metastasis, while tumor cell attachment to the tissue and secondary tumor formation the late phases. The assay system for the latter phase was set up with intra-portal-vein injection of pancreatic cancer cells. Intraperitoneal administration of DHMEQ was found to inhibit liver metastasis possibly by decreasing the expression of MMP-9 and IL-8. Also, when the pancreatic cancer cells treated with DHMEQ were inoculated into the peritoneal cavity of mice, the metastatic foci formation was inhibited. These results indicate that DHMEQ is likely to inhibit the late phase of metastasis. Meanwhile, we have recently employed three-dimensional (3D) culture of breast cancer cells for the model of early phase metastasis, since the 3D invasion just includes cell detachment and invasion into the matrix. DHMEQ inhibited the 3D invasion of breast cancer cells at 3D-nontoxic concentrations. In this way, DHMEQ was shown to inhibit the late and early phases of metastasis. Thus, DHMEQ is likely to be useful for the suppression of cancer metastasis.

PAR-2-mediated control of barrier function and motility differs between early and late phases of postinfectious gut dysfunction in the rat.

PubMed

Fernández-Blanco, Joan Antoni; Fernández-Blanco, Juan A; Hollenberg, Morley D; Martínez, Vicente; Vergara, Patri

2013-02-15

Proteinase-activated receptor-2 (PAR-2) and mast cell (MC) mediators contribute to inflammatory and functional gastrointestinal disorders. We aimed to characterize jejunal PAR-2-mediated responses and the potential MC involvement in the early and late phases of a rat model of postinfectious gut dysfunction. Jejunal tissues of control and Trichinella spiralis-infected (14 and 30 days postinfection) rats, treated or not with the MC stabilizer, ketotifen, were used. Histopathology and immunostaining were used to characterize inflammation, PAR-2 expression, and mucosal and connective tissue MCs. Epithelial barrier function (hydroelectrolytic transport and permeability) and motility were assessed in vitro in basal conditions and after PAR-2 activation. Intestinal inflammation on day 14 postinfection (early phase) was significantly resolved by day 30 (late phase) although MC counts and epithelial permeability remained increased. PAR-2-mediated ion transport (Ussing chambers, in vitro) and epithelial surface PAR-2 expression were reduced in the early phase, with a trend toward normalization during the late phase. In control conditions, PAR-2 activation (organ bath) induced biphasic motor responses (relaxation followed by excitation). At 14 days postinfection, spontaneous contractility and PAR-2-mediated relaxations were enhanced; motor responses were normalized on day 30. Postinfectious changes in PAR-2 functions were not affected by ketotifen treatment. We concluded that, in the rat model of Trichinella spiralis infection, alterations of intestinal PAR-2 function and expression depend on the inflammatory phase considered. A lack of a ketotifen effect suggests no interplay between MCs and PAR-2-mediated motility and ion transport alterations. These observations question the role of MC mediators in PAR-2-modulating postinfectious gut dysfunction.

Hepatic Hemangiomas: Factors Associated with Pseudo Washout Sign on Gd-EOB-DTPA-enhanced MR Imaging.

PubMed

Tateyama, Akihiro; Fukukura, Yoshihiko; Takumi, Koji; Shindo, Toshikazu; Kumagae, Yuichi; Nakamura, Fumihiko

2016-01-01

Our study aim was to clarify the characteristics of hemangiomas with pseudo washout sign (PWS) by comparing their features with those of hemangiomas without PWS on gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) imaging. We evaluated the features of hemangiomas on Gd-EOB-DTPA-enhanced MR imaging of 70 hepatic hemangiomas in 31 patients, investigating the presence of peripheral or central nodular enhancement, diffuse enhancement, and arterioportal shunt during the arterial phase, fill-in enhancement during the portal venous phase, and PWS, which is low signal intensity during the late phase. We visually assessed the intensity of contrast enhancement of the lesion during the arterial, portal venous, late, and hepatobiliary phases using a 4-grade scale and used the Fisher exact and Mann-Whitney U tests to compare hemangiomas with and without PWS. We observed PWS in 33 (47%) of 70 hemangiomas, which were significantly smaller than the hemangiomas without PWS (17.4 mm ± 20.3 versus 30.1 mm ± 28.5; P = 0.005); more frequent diffuse enhancement in hemangiomas with PWS than those without (21.2% versus 2.7%; P = 0.026); and no significant differences in nodular enhancement (P = 0.231), arterioportal shunt (P = 0.403), or fill-in enhancement (P = 0.357) between hemangiomas with and without PWS. Visually determined grades of tumor contrast enhancement were significantly lower in hemangiomas with PWS during the portal venous (P = 0.007) and late (P < 0.001) phases. Small hemangiomas tend to decrease in signal intensity during the portal venous phase and show PWS during the late phase.

Diffusive Imaging of Hydraulically Induced and Natural Fracture Systems

NASA Astrophysics Data System (ADS)

Eftekhari, B.; Marder, M. P.; Patzek, T. W.

2017-12-01

Hydraulic fracturing of tight shales continues to provide the US with a major source of energy. Efficiency of gas recovery in shales depends upon the geometry of the resulting network of fractures, the details of which are not yet fully understood. The present research explores how much of the underlying geometry can be deduced from the time dependence of the flow of gas out of the reservoir. We consider both ideal and real gas. In the case of real gas, we calculate production rate for parallel planar hydrofractures embedded in an infinite reservoir. Transport is governed by a nonlinear diffusion equation, which we solve exactly with a scaling curve. The scaling curve production rate declines initially as 1 over square root time, then as an exponential, and finally as 1 over square root of time again at late time. We show that for a given hydraulically fractured well, the onsets of transition between different decline regimes provides a direct estimate of a characteristic spacing of the underlying fracture network. We show that the scaling solution accurately fits the production history of more than 15,000 wells in the Barnett Shale. Almost all of the wells either have not yet transitioned into the late time decline or have been refractured while in exponential decline. However, there are 36 wells which show the late time transition. These allow us to calculate the characteristic spacing, which turns out to have a mode at about 10 m, a minimum at 1.6 m and a maximum at 13.3 m. We estimate that over 30 years these wells will produce on average about 45% more gas because of diffusion from the infinite external reservoir than they would if this contribution is neglected. Finally, we compute the rate at which ideal gas diffuses within an infinite region of rock into a specific absorbing fractal fracture network, which we model using geological constraints and percolation theory. Our solution employs a Brownian walk and the first passage kinetic Monte Carlo algorithm that is robust and efficient. A striking feature of this solution is the presence of a power law decline.

Seasonal Influenza Forecasting in Real Time Using the Incidence Decay With Exponential Adjustment Model

PubMed Central

Nasserie, Tahmina; Tuite, Ashleigh R; Whitmore, Lindsay; Hatchette, Todd; Drews, Steven J; Peci, Adriana; Kwong, Jeffrey C; Friedman, Dara; Garber, Gary; Gubbay, Jonathan

2017-01-01

Abstract Background Seasonal influenza epidemics occur frequently. Rapid characterization of seasonal dynamics and forecasting of epidemic peaks and final sizes could help support real-time decision-making related to vaccination and other control measures. Real-time forecasting remains challenging. Methods We used the previously described “incidence decay with exponential adjustment” (IDEA) model, a 2-parameter phenomenological model, to evaluate the characteristics of the 2015–2016 influenza season in 4 Canadian jurisdictions: the Provinces of Alberta, Nova Scotia and Ontario, and the City of Ottawa. Model fits were updated weekly with receipt of incident virologically confirmed case counts. Best-fit models were used to project seasonal influenza peaks and epidemic final sizes. Results The 2015–2016 influenza season was mild and late-peaking. Parameter estimates generated through fitting were consistent in the 2 largest jurisdictions (Ontario and Alberta) and with pooled data including Nova Scotia counts (R0 approximately 1.4 for all fits). Lower R0 estimates were generated in Nova Scotia and Ottawa. Final size projections that made use of complete time series were accurate to within 6% of true final sizes, but final size was using pre-peak data. Projections of epidemic peaks stabilized before the true epidemic peak, but these were persistently early (~2 weeks) relative to the true peak. Conclusions A simple, 2-parameter influenza model provided reasonably accurate real-time projections of influenza seasonal dynamics in an atypically late, mild influenza season. Challenges are similar to those seen with more complex forecasting methodologies. Future work includes identification of seasonal characteristics associated with variability in model performance. PMID:29497629

Exogenous carbonaceous matter in ancient martian sediments

NASA Astrophysics Data System (ADS)

Mojzsis, S. J.; Abramov, O.; Kereszturi, A.

2015-12-01

We re-evaluate the early evolution of an organic-matter rich (~10 wt. %) interplanetary dust particle flux to early Mars. Our work builds upon physical models that rely on plausible sources of exogenous debris and their dynamical rates of decay, the martian cratering record, and preservation of Noachian-Hesperian sedimentary units that have the potential to host organics. Post primary-accretionary scenarios that would have delivered abundant exogenous carbon to Mars can be imagined in two ways: a simple exponential decay with an approximately 100 Myr half-life, or as a "Sawtooth" timeline characterized by both faster-than-exponential decay from primary accretion and reduced total delivered mass. Indications are that a late bombardment spike was superposed on an otherwise broadly monotonic decline from primary accretion, of which two types are explored: a classical "Late Heavy Bombardment" (LHB) peak of impactors centered at ca. 3950 Ma and lasting 100 Myr, and a protracted bombardment typified by a sudden increase in impactor flux at ca. 4240-4100 Ma with a correspondingly longer decay time (400 Myr). Numerical models for each of the four bombardment scenarios explored in this work shows that exogenous organic matter could be a significant component of Noachian (ca. 4200-3700 Ma) and pre-Noachian (4500-4200 Ma) sediments. The discovery of organic-matter in martian sediments will be obfuscated by material of extra-areological origin. We predict that an earmark for the origin of this carbon would be correlated siderophile element abundances (e.g. Ni, Cr, and the platinoids). A time-dependent compositional relationship of C:HSEs would allow us to derive a chemochronology for pre-Hesperian (pre-3700 Ma) sedimentary units.

Cytokine expression during early and late phase of acute Puumala hantavirus infection

PubMed Central

2011-01-01

Background Hantaviruses of the family Bunyaviridae are emerging zoonotic pathogens which cause hemorrhagic fever with renal syndrome (HFRS) in the Old World and hantavirus pulmonary syndrome (HPS) in the New World. An immune-mediated pathogenesis is discussed for both syndromes. The aim of our study was to investigate cytokine expression during the course of acute Puumala hantavirus infection. Results We retrospectively studied 64 patients hospitalised with acute Puumala hantavirus infection in 2010 during a hantavirus epidemic in Germany. Hantavirus infection was confirmed by positive anti-hantavirus IgG/IgM. Cytokine expression of IL-2, IL-5, IL-6, IL-8, IL-10, IFN-γ, TNF-α and TGF-β1 was analysed by ELISA during the early and late phase of acute hantavirus infection (average 6 and 12 days after onset of symptoms, respectively). A detailed description of the demographic and clinical presentation of severe hantavirus infection requiring hospitalization during the 2010 hantavirus epidemic in Germany is given. Acute hantavirus infection was characterized by significantly elevated levels of IL-2, IL-6, IL-8, TGF-β1 and TNF-α in both early and late phase compared to healthy controls. From early to late phase of disease, IL-6, IL-10 and TNF-α significantly decreased whereas TGF-β1 levels increased. Disease severity characterized by elevated creatinine and low platelet counts was correlated with high pro-inflammatory IL-6 and TNF-α but low immunosuppressive TGF-β1 levels and vice versa . Conclusion High expression of cytokines activating T-lymphocytes, monocytes and macrophages in the early phase of disease supports the hypothesis of an immune-mediated pathogenesis. In the late phase of disease, immunosuppressive TGF-β1 level increase significantly. We suggest that delayed induction of a protective immune mechanism to downregulate a massive early pro-inflammatory immune response might contribute to the pathologies characteristic of human hantavirus infection. PMID:22085404

Theta Frequency Stimulation Induces a Local Form of Late Phase LTP in the CA1 Region of the Hippocampus

ERIC Educational Resources Information Center

Huang, Yan-You; Kandel, Eric R.

2005-01-01

The late phase of LTP (L-LTP) is typically induced by repeated high-frequency stimulation. This form of LTP requires activation of transcription and translation and results in the cell-wide distribution of gene products that can be captured by other marked synapses. Here we report that theta frequency stimulation (5 Hz, 30 sec) applied to the…

Late-time cosmological phase transitions

NASA Technical Reports Server (NTRS)

Schramm, David N.

1991-01-01

It is shown that the potential galaxy formation and large scale structure problems of objects existing at high redshifts (Z approx. greater than 5), structures existing on scales of 100 M pc as well as velocity flows on such scales, and minimal microwave anisotropies ((Delta)T/T) (approx. less than 10(exp -5)) can be solved if the seeds needed to generate structure form in a vacuum phase transition after decoupling. It is argued that the basic physics of such a phase transition is no more exotic than that utilized in the more traditional GUT scale phase transitions, and that, just as in the GUT case, significant random Gaussian fluctuations and/or topological defects can form. Scale lengths of approx. 100 M pc for large scale structure as well as approx. 1 M pc for galaxy formation occur naturally. Possible support for new physics that might be associated with such a late-time transition comes from the preliminary results of the SAGE solar neutrino experiment, implying neutrino flavor mixing with values similar to those required for a late-time transition. It is also noted that a see-saw model for the neutrino masses might also imply a tau neutrino mass that is an ideal hot dark matter candidate. However, in general either hot or cold dark matter can be consistent with a late-time transition.

Luteal phase clomiphene citrate for ovulation induction in women with polycystic ovary syndrome: a systematic review and meta-analysis.

PubMed

Ding, Nan; Chang, Jianbo; Jian, Qiliang; Liang, Xuefei; Liang, Zhongzhen; Wang, Fang

2016-11-01

To assess the efficacy of late luteal phase clomiphene citrate (CC) administration relative to early follicular phase CC for ovulation induction for polycystic ovary syndrome (PCOS). Review. A complete electronic databases including PubMed, Embase, The Cochrane Library, Web of Science, and CBM were searched for relevant randomized controlled trials (RCTs). The search was not restricted by language and publication time. Two reviewers selected trials and assessed trial quality by the Cochrane Handbook 5.1.0 independently. Four eligible RCT studies involving 708 women (934 cycles) were included. The results of the Meta-analysis: Late luteal phase group was associated with a number of higher total follicles (MD 1.82; 95% CI 0.86-2.78, p < 0.00001) and significant higher endometrial thickness on the day of HCG (MD 0.88; 95% CI 0.78-0.99, p < 0.00001) compared with early follicular group. There were no significant differences in the rate of pregnancy (RR 1.29; 95% CI 0.83-2.01, p = 0.26), ovulation rate (RR 0.99; 95% CI 0.86-1.14, p = 0.87), and abortion rate (RR 1.12; 95% CI 0.38 to 3.29, p = 0.84) between the two groups. It appeared that late luteal phase CC for ovulation induction might be an effective method for ovulation induction in women with PCOS compared to conventional CC administration. Further intensive randomized-controlled studies should be warranted to define the efficacy of CC used in late luteal phase.

Circadian Phase-Shifting Effects of Bright Light, Exercise, and Bright Light + Exercise

PubMed Central

Kline, Christopher E.; Elliott, Jeffrey A.; Zielinski, Mark R.; Devlin, Tina M.; Moore, Teresa A.

2016-01-01

Limited research has compared the circadian phase-shifting effects of bright light and exercise and additive effects of these stimuli. The aim of this study was to compare the phase-delaying effects of late night bright light, late night exercise, and late evening bright light followed by early morning exercise. In a within-subjects, counterbalanced design, 6 young adults completed each of three 2.5-day protocols. Participants followed a 3-h ultra-short sleep-wake cycle, involving wakefulness in dim light for 2h, followed by attempted sleep in darkness for 1 h, repeated throughout each protocol. On night 2 of each protocol, participants received either (1) bright light alone (5,000 lux) from 2210–2340 h, (2) treadmill exercise alone from 2210–2340 h, or (3) bright light (2210–2340 h) followed by exercise from 0410–0540 h. Urine was collected every 90 min. Shifts in the 6-sulphatoxymelatonin (aMT6s) cosine acrophase from baseline to post-treatment were compared between treatments. Analyses revealed a significant additive phase-delaying effect of bright light + exercise (80.8 ± 11.6 [SD] min) compared with exercise alone (47.3 ± 21.6 min), and a similar phase delay following bright light alone (56.6 ± 15.2 min) and exercise alone administered for the same duration and at the same time of night. Thus, the data suggest that late night bright light followed by early morning exercise can have an additive circadian phase-shifting effect. PMID:27103935

Effects of regular away travel on training loads, recovery, and injury rates in professional Australian soccer players.

PubMed

Fowler, Peter; Duffield, Rob; Waterson, Adam; Vaile, Joanna

2015-07-01

The current study examined the acute and longitudinal effects of regular away travel on training load (TL), player wellness, and injury surrounding competitive football (soccer) matches. Eighteen male professional football players, representing a team competing in the highest national competition in Australia, volunteered to participate in the study. Training loads, player wellness and injury incidence, rate, severity, and type, together with the activity at the time of injury, were recorded on the day before, the day of, and for 4 d after each of the 27 matches of the 2012-13 season. This included 14 home and 13 away matches, further subdivided based on the midpoint of the season into early (1-13) and late competition (14-27) phases. While TLs were significantly greater on day 3 at home compared with away during the early competition phase (P=.03), no other significant effects of match location were identified (P>.05). Total TL and mean wellness over the 6 d surrounding matches and TL on day 3 were significantly reduced during the late compared with the early competition phase at home and away (P<.05). Although not significantly (P>.05), training missed due to injury was 60% and 50% greater during the late than during the early competition phase at home and away, respectively. In conclusion, no significant interactions between match location and competition phase were evident during the late competition phase, which suggests that away travel had negligible cumulative effects on the reduction in player wellness in the latter half of the season.

Nonlinear analogue of the May−Wigner instability transition

PubMed Central

Fyodorov, Yan V.; Khoruzhenko, Boris A.

2016-01-01

We study a system of N≫1 degrees of freedom coupled via a smooth homogeneous Gaussian vector field with both gradient and divergence-free components. In the absence of coupling, the system is exponentially relaxing to an equilibrium with rate μ. We show that, while increasing the ratio of the coupling strength to the relaxation rate, the system experiences an abrupt transition from a topologically trivial phase portrait with a single equilibrium into a topologically nontrivial regime characterized by an exponential number of equilibria, the vast majority of which are expected to be unstable. It is suggested that this picture provides a global view on the nature of the May−Wigner instability transition originally discovered by local linear stability analysis. PMID:27274077

Effect of menstrual cycle phase on corticolimbic brain activation by visual food cues.

PubMed

Frank, Tamar C; Kim, Ginah L; Krzemien, Alicja; Van Vugt, Dean A

2010-12-02

Food intake is decreased during the late follicular phase and increased in the luteal phase of the menstrual cycle. While a changing ovarian steroid milieu is believed to be responsible for this behavior, the specific mechanisms involved are poorly understood. Brain activity in response to visual food stimuli was compared during the estrogen dominant peri-ovulatory phase and the progesterone dominant luteal phase of the menstrual cycle. Twelve women underwent functional magnetic resonance imaging during the peri-ovulatory and luteal phases of the menstrual cycle in a counterbalanced fashion. Whole brain T2* images were collected while subjects viewed pictures of high calorie (HC) foods, low calorie (LC) foods, and control (C) pictures presented in a block design. Blood oxygen level dependent (BOLD) signal in the late follicular phase and luteal phase was determined for the contrasts HC-C, LC-C, HC-LC, and LC-HC. Both HC and LC stimuli activated numerous corticolimbic brain regions in the follicular phase, whereas only HC stimuli were effective in the luteal phase. Activation of the nucleus accumbens (NAc), amygdala, and hippocampus in response to the HC-C contrast and the hippocampus in response to the LC-C contrast was significantly increased in the late follicular phase compared to the luteal phase. Activation of the orbitofrontal cortex and mid cingulum in response to the HC-LC contrast was greater during the luteal phase. These results demonstrate for the first time that brain responses to visual food cues are influenced by menstrual cycle phase. We postulate that ovarian steroid modulation of the corticolimbic brain contributes to changes in ingestive behavior during the menstrual cycle. Copyright © 2010 Elsevier B.V. All rights reserved.

Per-capita GDP and nonequilibrium wealth-concentration in a model for trade

NASA Astrophysics Data System (ADS)

Moukarzel, Cristian F.

2013-12-01

Data describing the per-capita Gross Domestic Product of around two hundred countries in years 1960 to 2008 are analyzed and found to decay approximately exponentially with rank. We discuss this experimental fact in the context of a wealth exchange model called Yard-Sale exchange, in which pairs of agents (i.e. nations) 'bet' for a fraction f of the wealth of the poorest of them. If the chances for this poorest agent to win the bet are not large enough, this model presents a 'wealth condensation' phase, in which one lucky agent gets to own the whole wealth in the end. In a recent study of this model [1], it was found that, in the condensed phase, the typical wealth of an agent with rank R decays exponentially with R. By establishing a parallel between wealth of a nation and its per-capita GDP, these observations suggest that international trade rules are such that strong wealth concentration is favored. Possible extensions of this work, that also consider endogenous factors affecting the evolution of GDP, are also discussed.

Dichromatic and monochromatic laser radiation effects on survival and morphology of Pantoea agglomerans

NASA Astrophysics Data System (ADS)

Thomé, A. M. C.; Souza, B. P.; Mendes, J. P. M.; Soares, L. C.; Trajano, E. T. L.; Fonseca, A. S.

2017-05-01

Despite the beneficial effects of low-level lasers on wound healing, their application for treatment of infected injuries is controversial because low-level lasers could stimulate bacterial growth exacerbating the infectious process. Thus, the aim of this work was to evaluate in vitro effects of low-level lasers on survival, morphology and cell aggregation of Pantoea agglomerans. P. agglomerans samples were isolated from human pressure injuries and cultures were exposed to low-level monochromatic and simultaneous dichromatic laser radiation to study the survival, cell aggregation, filamentation and morphology of bacterial cells in exponential and stationary growth phases. Fluence, wavelength and emission mode were those used in therapeutic protocols for wound healing. Data show no changes in morphology and cell aggregation, but dichromatic laser radiation decreased bacterial survival in exponential growth phase and monochromatic red and infrared lasers increased bacterial survival at the same fluence. Simultaneous dichromatic laser radiation induces biological effects that differ from those induced by monochromatic laser radiation and simultaneous dichromatic laser could be the option for treatment of infected pressure injuries by Pantoea agglomerans.

Entanglement entropy of a three-spin-interacting spin chain with a time-reversal-breaking impurity at one boundary.

PubMed

Nag, Tanay; Rajak, Atanu

2018-04-01

We investigate the effect of a time-reversal-breaking impurity term (of strength λ_{d}) on both the equilibrium and nonequilibrium critical properties of entanglement entropy (EE) in a three-spin-interacting transverse Ising model, which can be mapped to a p-wave superconducting chain with next-nearest-neighbor hopping and interaction. Importantly, we find that the logarithmic scaling of the EE with block size remains unaffected by the application of the impurity term, although, the coefficient (i.e., central charge) varies logarithmically with the impurity strength for a lower range of λ_{d} and eventually saturates with an exponential damping factor [∼exp(-λ_{d})] for the phase boundaries shared with the phase containing two Majorana edge modes. On the other hand, it receives a linear correction in term of λ_{d} for an another phase boundary. Finally, we focus to study the effect of the impurity in the time evolution of the EE for the critical quenching case where the impurity term is applied only to the final Hamiltonian. Interestingly, it has been shown that for all the phase boundaries, contrary to the equilibrium case, the saturation value of the EE increases logarithmically with the strength of impurity in a certain regime of λ_{d} and finally, for higher values of λ_{d}, it increases very slowly dictated by an exponential damping factor. The impurity-induced behavior of EE might bear some deep underlying connection to thermalization.

Entanglement entropy of a three-spin-interacting spin chain with a time-reversal-breaking impurity at one boundary

NASA Astrophysics Data System (ADS)

Nag, Tanay; Rajak, Atanu

2018-04-01

We investigate the effect of a time-reversal-breaking impurity term (of strength λd) on both the equilibrium and nonequilibrium critical properties of entanglement entropy (EE) in a three-spin-interacting transverse Ising model, which can be mapped to a p -wave superconducting chain with next-nearest-neighbor hopping and interaction. Importantly, we find that the logarithmic scaling of the EE with block size remains unaffected by the application of the impurity term, although, the coefficient (i.e., central charge) varies logarithmically with the impurity strength for a lower range of λd and eventually saturates with an exponential damping factor [˜exp(-λd) ] for the phase boundaries shared with the phase containing two Majorana edge modes. On the other hand, it receives a linear correction in term of λd for an another phase boundary. Finally, we focus to study the effect of the impurity in the time evolution of the EE for the critical quenching case where the impurity term is applied only to the final Hamiltonian. Interestingly, it has been shown that for all the phase boundaries, contrary to the equilibrium case, the saturation value of the EE increases logarithmically with the strength of impurity in a certain regime of λd and finally, for higher values of λd, it increases very slowly dictated by an exponential damping factor. The impurity-induced behavior of EE might bear some deep underlying connection to thermalization.

δ-exceedance records and random adaptive walks

NASA Astrophysics Data System (ADS)

Park, Su-Chan; Krug, Joachim

2016-08-01

We study a modified record process where the kth record in a series of independent and identically distributed random variables is defined recursively through the condition {Y}k\\gt {Y}k-1-{δ }k-1 with a deterministic sequence {δ }k\\gt 0 called the handicap. For constant {δ }k\\equiv δ and exponentially distributed random variables it has been shown in previous work that the process displays a phase transition as a function of δ between a normal phase where the mean record value increases indefinitely and a stationary phase where the mean record value remains bounded and a finite fraction of all entries are records (Park et al 2015 Phys. Rev. E 91 042707). Here we explore the behavior for general probability distributions and decreasing and increasing sequences {δ }k, focusing in particular on the case when {δ }k matches the typical spacing between subsequent records in the underlying simple record process without handicap. We find that a continuous phase transition occurs only in the exponential case, but a novel kind of first order transition emerges when {δ }k is increasing. The problem is partly motivated by the dynamics of evolutionary adaptation in biological fitness landscapes, where {δ }k corresponds to the change of the deterministic fitness component after k mutational steps. The results for the record process are used to compute the mean number of steps that a population performs in such a landscape before being trapped at a local fitness maximum.

Copper tolerance mediated by polyphosphate degradation and low-affinity inorganic phosphate transport system in Escherichia coli.

PubMed

Grillo-Puertas, Mariana; Schurig-Briccio, Lici Ariane; Rodríguez-Montelongo, Luisa; Rintoul, María Regina; Rapisarda, Viviana Andrea

2014-03-19

Metal tolerance in bacteria has been related to polyP in a model in which heavy metals stimulate the polymer hydrolysis, forming metal-phosphate complexes that are exported. As previously described in our laboratory, Escherichia coli cells grown in media containing a phosphate concentration >37 mM maintained an unusually high polyphosphate (polyP) level in stationary phase. The aim of the present work was to evaluate the influence of polyP levels as the involvement of low-affinity inorganic phosphate transport (Pit) system in E. coli copper tolerance. PolyP levels were modulated by the media phosphate concentration and/or using mutants in polyP metabolism. Stationary phase wild-type cells grown in high phosphate medium were significantly more tolerant to copper than those grown in sufficient phosphate medium. Copper addition to tolerant cells induced polyP degradation by PPX (an exopolyphosphatase), phosphate efflux and membrane polarization. ppk-ppx- (unable to synthesize/degrade polyP), ppx- (unable to degrade polyP) and Pit system mutants were highly sensitive to metal even in high phosphate media. In exponential phase, CopA and polyP-Pit system would act simultaneously to detoxify the metal or one could be sufficient to safeguard the absence of the other. Our results support a mechanism for copper detoxification in exponential and stationary phases of E. coli, involving Pit system and degradation of polyP. Data reflect the importance of the environmental phosphate concentration in the regulation of the microbial physiological state.

Exponential nonlinear electrodynamics and backreaction effects on holographic superconductor in the Lifshitz black hole background

NASA Astrophysics Data System (ADS)

Sherkatghanad, Z.; Mirza, B.; Lalehgani Dezaki, F.

We analytically describe the properties of the s-wave holographic superconductor with the exponential nonlinear electrodynamics in the Lifshitz black hole background in four-dimensions. Employing an assumption the scalar and gauge fields backreact on the background geometry, we calculate the critical temperature as well as the condensation operator. Based on Sturm-Liouville method, we show that the critical temperature decreases with increasing exponential nonlinear electrodynamics and Lifshitz dynamical exponent, z, indicating that condensation becomes difficult. Also we find that the effects of backreaction has a more important role on the critical temperature and condensation operator in small values of Lifshitz dynamical exponent, while z is around one. In addition, the properties of the upper critical magnetic field in Lifshitz black hole background using Sturm-Liouville approach is investigated to describe the phase diagram of the corresponding holographic superconductor in the probe limit. We observe that the critical magnetic field decreases with increasing Lifshitz dynamical exponent, z, and it goes to zero at critical temperature, independent of the Lifshitz dynamical exponent, z.

Timing of the endometrial biopsy may be critical for the accurate diagnosis of luteal phase deficiency.

PubMed

Castelbaum, A J; Wheeler, J; Coutifaris, C B; Mastroianni, L; Lessey, B A

1994-03-01

To determine the optimal time to perform the endometrial biopsy for the detection of "out-of-phase" endometrium. Two endometrial biopsies were performed during a single menstrual cycle in each subject. The patient's chronological day was determined by counting forward from the midcycle LH surge, as assessed by urinary LH detection. The "early" biopsy was done on day LH + 7.4 +/- 0.8, and the "late" biopsy on day LH + 11.6 +/- 0.7. Each biopsy was independently read by two pathologists and was considered out of phase if the histologic date was > or = 3 days delayed compared with the chronological date. Infertility practice of an academic teaching hospital. Thirty-three ovulatory women seeking evaluation for infertility. Number of patients with out-of-phase endometrium detected by the early versus the late biopsy. There was a significantly greater detection rate for out-of-phase endometrium using the early biopsy (12.1% to 18.2% incidence depending on the observer) compared with the later biopsy (6.1% to 9.1% incidence). A majority of the early out-of-phase biopsies corrected by the time of the later biopsy. Our findings indicate that an endometrial biopsy performed in the midluteal phase may detect a greater number of women with delayed endometrial maturation during the temporal window of embryo implantation. The observation that most of the women with out-of-phase midluteal biopsies had normal late luteal endometrium may represent a cryptic form of luteal phase deficiency.

Salivary hormones, IgA, and performance during intense training and tapering in judo athletes.

PubMed

Papacosta, Elena; Gleeson, Michael; Nassis, George P

2013-09-01

The aims of this study were to identify the time course of change of salivary testosterone (sT), cortisol (sC), and IgA (SIgA); mood state; and performance capacity during a 2-week taper in judo athletes and to examine the diurnal variation in these salivary markers. Eleven male judo athletes completed 5 weeks of training: 1 week of normal training (NORM), 2 weeks of intensified training (INT), and 2 weeks of exponential tapering (TAPER). Once per week subjects completed vertical and horizontal countermovement jump tests, a grip strength test, a Special Judo Fitness Test, a multistage aerobic fitness test, a 3 × 300-m run test, and anthropometric measurement. Subjects also completed questionnaires to assess mood state and muscle soreness. Two daily saliva samples (at 0700 and 1900) were collected at the end of each week during NORM and INT and every day during TAPER. Increased morning sT, decreased evening sC, lower muscle soreness, and enhanced mood state (p < 0.05) were evident by the early phases of TAPER. A significant 7.0% improvement in 3 × 300-m performance time, a 6.9% improvement in the vertical jump (p < 0.05), and increased morning and evening SIgA secretion rate (p < 0.01) were observed during the middle-late phases of TAPER. The higher values of salivary variables were observed in the morning. This study indicates that salivary hormones display diurnal variation. Furthermore, changes in hormonal responses, mood state, and muscle soreness precede enhancements in performance and mucosal immunity, suggesting that judo athletes taper for at least a week before competition.

Lactobacillus plantarum 299v surface-bound GAPDH: a new insight into enzyme cell walls location.

PubMed

Saad, N; Urdaci, M; Vignoles, C; Chaignepain, S; Tallon, R; Schmitter, J M; Bressollier, P

2009-12-01

The aim of this study was to provide new insight into the mechanism whereby the housekeeping enzyme glyceraldehyde-3-phosphate dehydrogenase (GAPDH) locates to cell walls of Lactobacillus plantarum 299v. After purification, cytosolic and cell wall GAPDH (cw-GAPDH) forms were characterized and shown to be identical homotetrameric active enzymes. GAPDH concentration on cell walls was growth-time dependent. Free GAPDH was not observed on the culture supernatant at any time during growth, and provoked cell lysis was not concomitant with any reassociation of GAPDH onto the cell surface. Hence, with the possibility of cw-GAPDH resulting from autolysis being unlikely, entrapment of intracellular GAPDH on the cell wall after a passive efflux through altered plasma membrane was investigated. Flow cytometry was used to assess L. plantarum 299v membrane permeabilization after labeling with propidium iodide (PI). By combining PI uptake and cw-GAPDH activity measurements, we demonstrate here that the increase in cw-GAPDH concentration from the early exponential phase to the late stationary phase is closely related to an increase in plasma membrane permeability during growth. Moreover, we observed that increases in both plasma membrane permeability and cw-GAPDH activity were delayed when glucose was added during L. plantarum 299v growth. Using a double labeling of L. plantarum 299v cells with anti-GAPDH antibodies and propidium iodide, we established unambiguously that cells with impaired membrane manifest five times more cw-GAPDH than unaltered cells. Our results show that plasma membrane permeability appears to be closely related to the efflux of GAPDH on the bacterial cell surface, offering new insight into the understanding of the cell wall location of this enzyme.

Effect of iron on accumulation of exotoxin A-specific mRNA in Pseudomonas aeruginosa.

PubMed Central

Lory, S

1986-01-01

A DNA probe from an internal fragment of the exotoxin A structural gene was used to study the effects of selected culture conditions on steady-state levels of exotoxin-specific mRNA in Pseudomonas aeruginosa. Cells grown under conditions of iron deprivation began to synthesize and excrete the exotoxin A polypeptide during the late exponential phase of growth and throughout the stationary phase of growth, concomitant with a sharp increase in exotoxin A mRNA pools in P. aeruginosa cells. The addition of iron to the medium resulted in the failure of these cells to synthesize exotoxin A mRNA, despite significantly enhanced growth. The inhibition of the production of exotoxin A and the accumulation of its mRNA by iron was dose dependent, with a half-maximal inhibitory concentration of FeSO4 of 5 to 10 microM. A blockade of the initiation of transcription by rifampin resulted in the decay of exotoxin A mRNA, with a half-life of approximately 8 to 10 min, depending on the media used for growth. The addition of iron to cells actively engaged in exotoxin A synthesis also resulted in a gradual decrease in the amount of this mRNA in bacteria. However, the rate of decline of mRNA induced by iron was relatively slow (half-life, 90 min), with a considerable lag time between the iron addition and the first detectable effect on mRNA. While iron clearly appears to influence the production of exotoxin A at the transcriptional level, the molecular basis of this effect may involve several interacting factors affecting the initiation of transcription and perhaps mRNA turnover. Images PMID:2430950

Role of UME6 in transcriptional regulation of a DNA repair gene in Saccharomyces cerevisiae.

PubMed

Sweet, D H; Jang, Y K; Sancar, G B

1997-11-01

In Saccharomyces cerevisiae UV radiation and a variety of chemical DNA-damaging agents induce the transcription of specific genes, including several involved in DNA repair. One of the best characterized of these genes is PHR1, which encodes the apoenzyme for DNA photolyase. Basal-level and damage-induced expression of PHR1 require an upstream activation sequence, UAS(PHR1), which has homology with DRC elements found upstream of at least 19 other DNA repair and DNA metabolism genes in yeast. Here we report the identification of the UME6 gene of S. cerevisiae as a regulator of UAS(PHR1) activity. Multiple copies of UME6 stimulate expression from UAS(PHR1) and the intact PHR1 gene. Surprisingly, the effect of deletion of UME6 is growth phase dependent. In wild-type cells PHR1 is induced in late exponential phase, concomitant with the initiation of glycogen accumulation that precedes the diauxic shift. Deletion of UME6 abolishes this induction, decreases the steady-state concentration of photolyase molecules and PHR1 mRNA, and increases the UV sensitivity of a rad2 mutant. Despite the fact that UAS(PHR1) does not contain the URS1 sequence, which has been previously implicated in UME6-mediated transcriptional regulation, we find that Ume6p binds to UAS(PHR1) with an affinity and a specificity similar to those seen for a URS1 site. Similar binding is also seen for DRC elements from RAD2, RAD7, and RAD53, suggesting that UME6 contributes to the regulated expression of a subset of damage-responsive genes in yeast.

Wigner functions for evanescent waves.

PubMed

Petruccelli, Jonathan C; Tian, Lei; Oh, Se Baek; Barbastathis, George

2012-09-01

We propose phase space distributions, based on an extension of the Wigner distribution function, to describe fields of any state of coherence that contain evanescent components emitted into a half-space. The evanescent components of the field are described in an optical phase space of spatial position and complex-valued angle. Behavior of these distributions upon propagation is also considered, where the rapid decay of the evanescent components is associated with the exponential decay of the associated phase space distributions. To demonstrate the structure and behavior of these distributions, we consider the fields generated from total internal reflection of a Gaussian Schell-model beam at a planar interface.

Autolysis of Escherichia coli and Bacillus subtilis cells in low gravity

NASA Technical Reports Server (NTRS)

Kacena, M. A.; Smith, E. E.; Todd, P.

1999-01-01

The role of gravity in the autolysis of Bacillus subtilis and Escherichia coli was studied by growing cells on Earth and in microgravity on Space Station Mir. Autolysis analysis was completed by examining the death phase or exponential decay of cells for approximately 4 months following the stationary phase. Consistent with published findings, the stationary-phase cell population was 170% and 90% higher in flight B. subtilis and E. coli cultures, respectively, than in ground cultures. Although both flight autolysis curves began at higher cell densities than control curves, the rate of autolysis in flight cultures was identical to that of their respective ground control rates.

Earthquake potential in California-Nevada implied by correlation of strain rate and seismicity

USGS Publications Warehouse

Zeng, Yuehua; Petersen, Mark D.; Shen, Zheng-Kang

2018-01-01

Rock mechanics studies and dynamic earthquake simulations show that patterns of seismicity evolve with time through (1) accumulation phase, (2) localization phase, and (3) rupture phase. We observe a similar pattern of changes in seismicity during the past century across California and Nevada. To quantify these changes, we correlate GPS strain rates with seismicity. Earthquakes of M > 6.5 are collocated with regions of highest strain rates. By contrast, smaller magnitude earthquakes of M ≥ 4 show clear spatiotemporal changes. From 1933 to the late 1980s, earthquakes of M ≥ 4 were more diffused and broadly distributed in both high and low strain rate regions (accumulation phase). From the late 1980s to 2016, earthquakes were more concentrated within the high strain rate areas focused on the major fault strands (localization phase). In the same time period, the rate of M > 6.5 events also increased significantly in the high strain rate areas. The strong correlation between current strain rate and the later period of seismicity indicates that seismicity is closely related to the strain rate. The spatial patterns suggest that before the late 1980s, the strain rate field was also broadly distributed because of the stress shadows from previous large earthquakes. As the deformation field evolved out of the shadow in the late 1980s, strain has refocused on the major fault systems and we are entering a period of increased risk for large earthquakes in California.

Local antinociceptive action of fluoxetine in the rat formalin assay: role of l-arginine/nitric oxide/cGMP/KATP channel pathway.

PubMed

Ghorbanzadeh, Behnam; Mansouri, Mohammad Taghi; Naghizadeh, Bahareh; Alboghobeish, Soheila

2018-02-01

The present study was conducted to evaluate the local antinociceptive actions of fluoxetine, a selective serotonin reuptake inhibitor, and the possible involvement of the l-arginine/NO/cGMP/K ATP channel pathway in this effect using the formalin test in rats. To elucidate the underlying mechanisms, animals were pre-treated with l-NAME, aminoguanidine, methylene blue, glibenclamide, l-arginine, sodium nitroprusside, or diazoxide. Local ipsilateral, but not contralateral, administration of fluoxetine (10-300 μg/paw) dose-dependently suppressed flinching number during both early and late phases of the test, and this was comparable with morphine also given peripherally. Pre-treatment with l-NAME, aminoguanidine, methylene blue, or glibenclamide dose-dependently prevented fluoxetine (100 μg/paw)-induced antinociception in the late phase. In contrast, administration of l-arginine, sodium nitroprusside, and diazoxide significantly enhanced the antinociception caused by fluoxetine in the late phase of the test. However, these treatments had no significant effect on the antinociceptive response of fluoxetine in the early phase of the formalin test. Our data demonstrate that local peripheral antinociception of fluoxetine during the late phase of the formalin test could be due to activation of l-arginine/NO/cGMP/K ATP channel pathway. The peripheral action of fluoxetine raises the possibility that topical application of this drug (e.g., as a cream, ointment, or jelly) may be a useful method for relieving the inflammatory pain states.

Earthquake Potential in California-Nevada Implied by Correlation of Strain Rate and Seismicity

NASA Astrophysics Data System (ADS)

Zeng, Yuehua; Petersen, Mark D.; Shen, Zheng-Kang

2018-02-01

Rock mechanics studies and dynamic earthquake simulations show that patterns of seismicity evolve with time through (1) accumulation phase, (2) localization phase, and (3) rupture phase. We observe a similar pattern of changes in seismicity during the past century across California and Nevada. To quantify these changes, we correlate GPS strain rates with seismicity. Earthquakes of M > 6.5 are collocated with regions of highest strain rates. By contrast, smaller magnitude earthquakes of M ≥ 4 show clear spatiotemporal changes. From 1933 to the late 1980s, earthquakes of M ≥ 4 were more diffused and broadly distributed in both high and low strain rate regions (accumulation phase). From the late 1980s to 2016, earthquakes were more concentrated within the high strain rate areas focused on the major fault strands (localization phase). In the same time period, the rate of M > 6.5 events also increased significantly in the high strain rate areas. The strong correlation between current strain rate and the later period of seismicity indicates that seismicity is closely related to the strain rate. The spatial patterns suggest that before the late 1980s, the strain rate field was also broadly distributed because of the stress shadows from previous large earthquakes. As the deformation field evolved out of the shadow in the late 1980s, strain has refocused on the major fault systems and we are entering a period of increased risk for large earthquakes in California.

Post-collisional magmatism in the central East African Orogen: The Maevarano Suite of north Madagascar

NASA Astrophysics Data System (ADS)

Goodenough, K. M.; Thomas, R. J.; De Waele, B.; Key, R. M.; Schofield, D. I.; Bauer, W.; Tucker, R. D.; Rafahatelo, J.-M.; Rabarimanana, M.; Ralison, A. V.; Randriamananjara, T.

2010-04-01

Late tectonic, post-collisional granite suites are a feature of many parts of the Late Neoproterozoic to Cambrian East African Orogen (EAO), where they are generally attributed to late extensional collapse of the orogen, accompanied by high heat flow and asthenospheric uprise. The Maevarano Suite comprises voluminous plutons which were emplaced in some of the tectonostratigraphic terranes of northern Madagascar, in the central part of the EAO, following collision and assembly during a major orogeny at ca. 550 Ma. The suite comprises three main magmatic phases: a minor early phase of foliated gabbros, quartz diorites, and granodiorites; a main phase of large batholiths of porphyritic granitoids and charnockites; and a late phase of small-scale plutons and sheets of monzonite, syenite, leucogranite and microgranite. The main phase intrusions tend to be massive, but with variably foliated margins. New U-Pb SHRIMP zircon data show that the whole suite was emplaced between ca. 537 and 522 Ma. Geochemically, all the rocks of the suite are enriched in the LILE, especially K, and the LREE, but are relatively depleted in Nb, Ta and the HREE. These characteristics are typical of post-collisional granitoids in the EAO and many other orogenic belts. It is proposed that the Maevarano Suite magmas were derived by melting of sub-continental lithospheric mantle that had been enriched in the LILE during earlier subduction events. The melting occurred during lithospheric delamination, which was associated with extensional collapse of the East African Orogen.

Characterizing the reproduction number of epidemics with early subexponential growth dynamics

PubMed Central

Viboud, Cécile; Simonsen, Lone; Moghadas, Seyed M.

2016-01-01

Early estimates of the transmission potential of emerging and re-emerging infections are increasingly used to inform public health authorities on the level of risk posed by outbreaks. Existing methods to estimate the reproduction number generally assume exponential growth in case incidence in the first few disease generations, before susceptible depletion sets in. In reality, outbreaks can display subexponential (i.e. polynomial) growth in the first few disease generations, owing to clustering in contact patterns, spatial effects, inhomogeneous mixing, reactive behaviour changes or other mechanisms. Here, we introduce the generalized growth model to characterize the early growth profile of outbreaks and estimate the effective reproduction number, with no need for explicit assumptions about the shape of epidemic growth. We demonstrate this phenomenological approach using analytical results and simulations from mechanistic models, and provide validation against a range of empirical disease datasets. Our results suggest that subexponential growth in the early phase of an epidemic is the rule rather the exception. Mechanistic simulations show that slight modifications to the classical susceptible–infectious–removed model result in subexponential growth, and in turn a rapid decline in the reproduction number within three to five disease generations. For empirical outbreaks, the generalized-growth model consistently outperforms the exponential model for a variety of directly and indirectly transmitted diseases datasets (pandemic influenza, measles, smallpox, bubonic plague, cholera, foot-and-mouth disease, HIV/AIDS and Ebola) with model estimates supporting subexponential growth dynamics. The rapid decline in effective reproduction number predicted by analytical results and observed in real and synthetic datasets within three to five disease generations contrasts with the expectation of invariant reproduction number in epidemics obeying exponential growth. The generalized-growth concept also provides us a compelling argument for the unexpected extinction of certain emerging disease outbreaks during the early ascending phase. Overall, our approach promotes a more reliable and data-driven characterization of the early epidemic phase, which is important for accurate estimation of the reproduction number and prediction of disease impact. PMID:27707909

Metabolism of nC11 fatty acid fed to Trichoderma koningii and Penicillium janthinellum II: Production of intracellular and extracellular lipids.

PubMed

Monreal, Carlos M; Chahal, Amarpreet; Rowland, Owen; Smith, Myron; Schnitzer, Morris

2014-01-01

Little is known about the fungal metabolism of nC10 and nC11 fatty acids and their conversion into lipids. A mixed batch culture of soil fungi, T. koningii and P. janthinellum, was grown on undecanoic acid (UDA), a mixture of UDA and potato dextrose broth (UDA+PDB), and PDB alone to examine their metabolic conversion during growth. We quantified seven intracellular and extracellular lipid classes using Iatroscan thin-layer chromatography with flame ionization detection (TLC-FID). Gas chromatography with flame ionization detection (GC-FID) was used to quantify 42 individual fatty acids. Per 150 mL culture, the mixed fungal culture grown on UDA+PDB produced the highest amount of intracellular (531 mg) and extracellular (14.7 mg) lipids during the exponential phase. The content of total intracellular lipids represented 25% of the total biomass-carbon, or 10% of the total biomass dry weight produced. Fatty acids made up the largest class of intracellular lipids (457 mg/150 mL culture) and they were synthesized at a rate of 2.4 mg/h during the exponential phase, and decomposed at a rate of 1.8 mg/h during the stationary phase, when UDA+PDB was the carbon source. Palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2) and vaccenic acid (C18:1) accounted for >80% of the total intracellular fatty acids. During exponential growth on UDA+PDB, hydrocarbons were the largest pool of all extracellular lipids (6.5 mg), and intracellularly they were synthesized at a rate of 64 μg/h. The mixed fungal species culture of T. koningii and P. janthinellum produced many lipids for potential use as industrial feedstocks or bioproducts in biorefineries.

Effects of stepwise nitrogen depletion on carotenoid content, fluorescence parameters and the cellular stoichiometry of Chlorella vulgaris

NASA Astrophysics Data System (ADS)

Zhang, Ping; Li, Zhe; Lu, Lunhui; Xiao, Yan; Liu, Jing; Guo, Jinsong; Fang, Fang

2017-06-01

Stressful conditions can stimulate the accumulation of carotenoids in some microalgae. To obtain more knowledge of the stress response, we studied the effects of different N concentrations on unicellular content of carotenoids using Raman spectroscopic technique; cellular stoichiometric changes and the fluorescence parameters of Chlorella vulgaris were concomitantly studied. Initially, we optimized the Raman scattering conditions and demonstrated the feasibility of unicellular carotenoid analysis by Raman spectroscopic technique. The results showed that an integration time of 10 s, laser power at 0.1 mW and an accumulation time of 1 were the optimum conditions, and the peak height at 1523 cm- 1 scaled linearly with the carotenoid content in the range of 0.625-1440 mg/L with a recovery rate of 97% 103%. In the experiment, seven different nitrogen levels ranging from 0 to 2.48 × 105 μg/L were imposed. Samples were taken at the start, exponential phase and end of the experiment. The results showed that nitrogen stress can facilitate the synthesis of carotenoids, while at the same time, excessive nitrogen stress led to lower proliferative and photosynthetic activity. Compared with carotenoids, chlorophylls were more sensitive to nitrogen stress; it declined dramatically as stress processed. There existed no significant differences for Fv/Fm among different nitrogen levels during the exponential phase, while in the end, it declined and a significant difference appeared between cells in 2.48 × 105 μg/L N and other experimental levels. Photosynthetic efficiency, namely the C/N mole ratio in algal cells, didnot significantly change during the exponential phase; however, apparent increases ultimately occurred, except for the stable C/N in BG11 medium. This increase matched well with the carotenoid decline, indicating that an increasing cellular C/N mole ratio can be used as an indicator of excessive stress in carotenoid production. Besides, there also existed an inverse correlation with ETRmax.

Non-minimally coupled condensate cosmologies: a phase space analysis

NASA Astrophysics Data System (ADS)

Carloni, Sante; Vignolo, Stefano; Cianci, Roberto

2014-09-01

We present an analysis of the phase space of cosmological models based on a non-minimal coupling between the geometry and a fermionic condensate. We observe that the strong constraint coming from the Dirac equations allows a detailed design of the cosmology of these models, and at the same time guarantees an evolution towards a state indistinguishable from general relativistic cosmological models. In this light, we show in detail how the use of some specific potentials can naturally reproduce a phase of accelerated expansion. In particular, we find for the first time that an exponential potential is able to induce two de Sitter phases separated by a power law expansion, which could be an interesting model for the unification of an inflationary phase and a dark energy era.

The Origin of the EUV Late Phase: A Case Study of the C8.8 Flare on 2010 May 5

NASA Technical Reports Server (NTRS)

Hock, R. A.; Woods, T. N.; Klimchuk, J. A.; Eparvier, F. G.; Jones, A. R.

2012-01-01

Since the launch of NASA's Solar Dynamics Observatory on 2010 February 11, the Extreme ultraviolet Variability Experiment (EVE) has observed numerous flares. One interesting feature observed by EVE is that a subset of flares exhibit an additional enhancement of the 2-3 million K emission several hours after the flares soft X-ray emission. From the Atmospheric Imaging Assembly (AIA) images, we observe that this secondary emission, dubbed the EUV late phase, occurs in the same active region as the flare but not in the same coronal loops. Here, we examine the C8.8 flare that occurred on 2010 May 5 as a case study of EUV late phase flares. In addition to presenting detailed observations from both AIA and EVE, we develop a physical model of this flare and test it using the Enthalpy Based Thermal Evolution of Loops (EBTEL) model.

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay.

PubMed

Tassino, Bettina; Horta, Stefany; Santana, Noelia; Levandovski, Rosa; Silva, Ana

2016-01-01

In humans, a person's chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals' chronotype, whose values (around 6 a.m.) are the latest ever reported. We found a SJL of around 2 h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light-dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration.

Learning phase transitions by confusion

NASA Astrophysics Data System (ADS)

van Nieuwenburg, Evert P. L.; Liu, Ye-Hua; Huber, Sebastian D.

2017-02-01

Classifying phases of matter is key to our understanding of many problems in physics. For quantum-mechanical systems in particular, the task can be daunting due to the exponentially large Hilbert space. With modern computing power and access to ever-larger data sets, classification problems are now routinely solved using machine-learning techniques. Here, we propose a neural-network approach to finding phase transitions, based on the performance of a neural network after it is trained with data that are deliberately labelled incorrectly. We demonstrate the success of this method on the topological phase transition in the Kitaev chain, the thermal phase transition in the classical Ising model, and the many-body-localization transition in a disordered quantum spin chain. Our method does not depend on order parameters, knowledge of the topological content of the phases, or any other specifics of the transition at hand. It therefore paves the way to the development of a generic tool for identifying unexplored phase transitions.

Photosystem II Component Lifetimes in the Cyanobacterium Synechocystis sp. Strain PCC 6803

PubMed Central

Yao, Danny C. I.; Brune, Daniel C.; Vavilin, Dmitri; Vermaas, Wim F. J.

2012-01-01

To gain insight in the lifetimes of photosystem II (PSII) chlorophyll and proteins, a combined stable isotope labeling (15N)/mass spectrometry method was used to follow both old and new pigments and proteins. Photosystem I-less Synechocystis cells were grown to exponential or post-exponential phase and then diluted in BG-11 medium with [15N]ammonium and [15N]nitrate. PSII was isolated, and the masses of PSII protein fragments and chlorophyll were determined. Lifetimes of PSII components ranged from 1.5 to 40 h, implying that at least some of the proteins and chlorophyll turned over independently from each other. Also, a significant amount of nascent PSII components accumulated in thylakoids when cells were in post-exponential growth phase. In a mutant lacking small Cab-like proteins (SCPs), most PSII protein lifetimes were unaffected, but the lifetime of chlorophyll and the amount of nascent PSII components that accumulated were decreased. In the absence of SCPs, one of the PSII biosynthesis intermediates, the monomeric PSII complex without CP43, was missing. Therefore, SCPs may stabilize nascent PSII protein complexes. Moreover, upon SCP deletion, the rate of chlorophyll synthesis and the accumulation of early tetrapyrrole precursors were drastically reduced. When [14N]aminolevulinic acid (ALA) was supplemented to 15N-BG-11 cultures, the mutant lacking SCPs incorporated much more exogenous ALA into chlorophyll than the control demonstrating that ALA biosynthesis was impaired in the absence of SCPs. This illustrates the major effects that nonstoichiometric PSII components such as SCPs have on intermediates and assembly but not on the lifetime of PSII proteins. PMID:22090028

Synaptic potentials in respiratory neurones during evoked phase switching after NMDA receptor blockade in the cat

PubMed Central

Pierrefiche, O; Haji, A; Foutz, A S; Takeda, R; Champagnat, J; Denavit-Saubié, M

1998-01-01

Blockade of NMDA receptors by dizocilpine impairs the inspiratory off-switch (IOS) of central origin but not the IOS evoked by stimulation of sensory afferents. To investigate whether this difference was due to the effects of different patterns of synaptic interactions on respiratory neurones, we stimulated electrically the superior laryngeal nerve (SLN) or vagus nerve in decerebrate cats before and after i.v. administration of dizocilpine, whilst recording intracellularly. Phrenic nerve responses to ipsilateral SLN or vagal stimulation were: at mid-inspiration, a transient inhibition often followed by a brief burst of activity; at late inspiration, an IOS; and at mid-expiration, a late burst of activity. In all neurones (n = 16), SLN stimulation at mid-inspiration evoked an early EPSP during phase 1 (latency to the arrest of phrenic nerve activity), followed by an IPSP in inspiratory (I) neurones (n = 8) and by a wave of EPSPs in post-inspiratory (PI) neurones (n = 8) during phase 2 (inhibition of phrenic activity). An EPSP in I neurones and an IPSP in PI neurones occurred during phase 3 (brief phrenic burst) following phase 2. Evoked IOS was associated with a fast (phase 1) activation of PI neurones, whereas during spontaneous IOS, a progressive (30-50 ms) depolarization of PI neurones preceded the arrest of phrenic activity. Phase 3 PSPs were similar to those occurring during the burst of activity seen at the start of spontaneous inspiration. Dizocilpine did not suppress the evoked phrenic inhibition and the late burst of activity. The shapes and timing of the evoked PSPs and the changes in membrane potential in I and PI neurones during the phase transition were not altered. We hypothesize that afferent sensory pathways not requiring NMDA receptors (1) terminate inspiration through a premature activation of PI neurones, and (2) evoke a late burst of phrenic activity which might be the first stage of the inspiratory on-switch. PMID:9508816

Exponential asymptotics of homoclinic snaking

NASA Astrophysics Data System (ADS)

Dean, A. D.; Matthews, P. C.; Cox, S. M.; King, J. R.

2011-12-01

We study homoclinic snaking in the cubic-quintic Swift-Hohenberg equation (SHE) close to the onset of a subcritical pattern-forming instability. Application of the usual multiple-scales method produces a leading-order stationary front solution, connecting the trivial solution to the patterned state. A localized pattern may therefore be constructed by matching between two distant fronts placed back-to-back. However, the asymptotic expansion of the front is divergent, and hence should be truncated. By truncating optimally, such that the resultant remainder is exponentially small, an exponentially small parameter range is derived within which stationary fronts exist. This is shown to be a direct result of the 'locking' between the phase of the underlying pattern and its slowly varying envelope. The locking mechanism remains unobservable at any algebraic order, and can only be derived by explicitly considering beyond-all-orders effects in the tail of the asymptotic expansion, following the method of Kozyreff and Chapman as applied to the quadratic-cubic SHE (Chapman and Kozyreff 2009 Physica D 238 319-54, Kozyreff and Chapman 2006 Phys. Rev. Lett. 97 44502). Exponentially small, but exponentially growing, contributions appear in the tail of the expansion, which must be included when constructing localized patterns in order to reproduce the full snaking diagram. Implicit within the bifurcation equations is an analytical formula for the width of the snaking region. Due to the linear nature of the beyond-all-orders calculation, the bifurcation equations contain an analytically indeterminable constant, estimated in the previous work by Chapman and Kozyreff using a best fit approximation. A more accurate estimate of the equivalent constant in the cubic-quintic case is calculated from the iteration of a recurrence relation, and the subsequent analytical bifurcation diagram compared with numerical simulations, with good agreement.

Applications of mutant yeast strains with low glycogen storage capability

NASA Technical Reports Server (NTRS)

Petersen, G. R.; Schubert, W. W.; Stokes, B. O.

1981-01-01

Several strains of Hansenula polymorpha were selected for possible low glycogen storage characteristics based on a selective I2 staining procedure. The levels of storage carbohydrates in the mutant strains were found to be 44-70% of the levels in the parent strain for cultures harvested in stationary phase. Similar differences generally were not found for cells harvested in exponential phase. Yeast strains deficient in glycogen storage capability are valuable in increasing the relative protein value of microbial biomass and also may provide significant cost savings in substrate utilization in fermentative processes.

Luteal phase deficiency: abnormal gonadotropin and progesterone secretion patterns.

PubMed

Soules, M R; Clifton, D K; Cohen, N L; Bremner, W J; Steiner, R A

1989-10-01

Luteal phase deficiency (LPD) is a reproductive disorder associated with infertility and spontaneous abortion. This study was undertaken to determine whether LPD might be related to an abnormal pattern of gonadotropin secretion. We tested this hypothesis by evaluating the pattern of pulsatile LH secretion in both the follicular and luteal phases of the menstrual cycle in normal women (n = 21) and women with LPD (n = 20), which was diagnosed on the basis of two out of phase endometrial biopsies. In addition, we sought to determine whether changes in progesterone (P) pulse patterns could account for the decrease in average serum P levels in women with LPD. To this end, we examined the pulse patterns of P and compared these patterns between normal women and those with LPD. Frequent blood sampling was performed in both groups to determine their respective hormone secretion patterns. In the follicular phase, blood samples were obtained every 10 min for 12 h; in the luteal phase the samples were obtained every 10 min for 12 h; in the luteal LH, FSH, and P were assayed in each sample. Pulse detection was performed by an adaptive threshold method of pulse analysis. The LH pulse frequency was significantly higher in the women with LPD than in the normal women in the early follicular phase [P less than 0.05; LPD, 12.8 +/- 1.4 (+/- SE); normal, 8.2 +/- 0.7 pulses/12 h]. LH pulse frequency was similar in the early and late follicular phases in the women with LPD, whereas it was higher in the late follicular phase in normal women. Mean serum FSH levels were not different between groups in both the early and late follicular phases. In the luteal phase the P pulse amplitude and mean serum P level were significantly lower in the LPD group than in the normal women (P less than 0.01). We conclude that 1) a too rapid LH pulse pattern in the early follicular phase may lead to inadequate LH support of the corpus luteum and become manifest as LPD; 2) the mechanism for inadequate P secretion in LPD is decreased P pulse amplitude; 3) the finding of similar serum FSH levels in the two groups in both the early and late follicular phases did not support compromised folliculogenesis as an etiological factor for LPD.

Thermal Emissions Spanning the Prompt and the Afterglow Phases of the Ultra-long GRB 130925A

NASA Astrophysics Data System (ADS)

Basak, Rupal; Rao, A. R.

2015-07-01

GRB 130925A is an ultra-long gamma-ray burst (GRB), and it shows clear evidence for thermal emission in the soft X-ray data of the Swift/X-ray Telescope (XRT; ∼0.5 keV), lasting until the X-ray afterglow phase. Due to the long duration of the GRB, the burst could be studied in hard X-rays with high-resolution focusing detectors (NuSTAR). The blackbody temperature, as measured by the Swift/XRT, shows a decreasing trend until the late phase (Piro et al.) whereas the high-energy data reveal a significant blackbody component during the late epochs at an order of magnitude higher temperature (∼5 keV) compared to contemporaneous low energy data (Bellm et al.). We resolve this apparent contradiction by demonstrating that a model with two black bodies and a power law (2BBPL) is consistent with the data right from the late prompt emission to the afterglow phase. Both blackbodies show a similar cooling behavior up to late times. We invoke a structured jet, having a fast spine and a slower sheath layer, to identify the location of these blackbodies. Independent of the physical interpretation, we propose that the 2BBPL model is a generic feature of the prompt emission of all long GRBs, and the thermal emission found in the afterglow phase of different GRBs reflects the lingering thermal component of the prompt emission with different timescales. We strengthen this proposal by pointing out a close similarity between the spectral evolutions of this GRB and GRB 090618, a source with significant wide band data during the early afterglow phase.

Biodegradation of Dense Non-Aqueous Phase Liquids (DNAPL) Through Bioaugmentation of Source Areas - Dover National Test Site, Dover, Delaware

DTIC Science & Technology

2008-08-01

the distribution of DNAPL. The OSU research team evaluated the use of radon as a partitioning groundwater tracer. The DNAPL release fulfilled one...close to the source area generated more PCE equivalent mass over time. The exponential decay from the fitted line (predicted PCE, orange line in each

Effect of rapid cooling and acidic pH on cellular homeostasis of Pectinatus frisingensis, a strictly anaerobic beer-spoilage bacterium.

PubMed

Chihib, N E; Tholozan, J L

1999-06-01

Pectinatus frisingensis is a strictly anaerobic mesophilic bacterium involved in bottled beer spoilage. Cellular volume, adenylate energy charge, intracellular pH and intracellular potassium concentration measurements were performed in late exponential-phase cell suspensions placed in different physiological conditions, to evaluate the capability of this bacterium to maintain cellular homeostasis. The intracellular pH was calculated from the intracellular accumulation of a [carboxyl-14C]benzoic acid. Optimum physiological conditions were the presence of a carbon source and pH of 6.2, hostile conditions were a pH 4.5, absence of a carbon source, and rapid cooling treatment. The cell was able to maintain a higher intracellular pH than the external pH under all conditions. Intracellular volume was lower at pH 4.5 than at pH 6.2. A low net potassium efflux rate was routinely measured in starving cells, while glucose addition promoted immediate net potassium uptake from the medium. Cooling treatment resulted in sudden net potassium efflux from the cell, a decrease of the intracellular pH, and low modifications of the adenylate energy charge in metabolizing-glucose cell suspensions. Thus, cold treatment perturbs the P. frisingensis homeostasis but the bacteria were able to restore their homeostasis in the presence of a carbon source, and under warm conditions.

Antioxidants Potential of the Filamentous Fungi (Mucor circinelloides)

PubMed Central

Hussain, Syed Ammar; Yang, Junhuan; Ijaz, Muhammad Umair; Liu, Qing; Song, Yuanda

2017-01-01

Three important strains of Mucor circinelloides grown in complete and minimal media for specified period (72 h, 120 h and 168 h) under submerged fermentation conditions were investigated for their potential antioxidants/secondary metabolite production. All mycelial extracts demonstrated effective antioxidant activities in terms of β-carotene/linoleic acid bleaching, radical scavenging, reduction of metal ions and chelating abilities against ferrous ions. Different extraction methods and solvent systems affected the recovery yield and antioxidant activities of the extracts significantly (p ≤ 0.05). Ethanolic extracts were found to be rich source of antioxidant components and subsequently more effective in antioxidant properties. Fermentation period and media used also significantly affected (p ≤ 0.05) the antioxidant production and the resulting antioxidant properties. The (ethanolic) extracts of all the strains from late exponential growth phase (120 h) showed highest antioxidant production with topmost reducing, chelating and radical scavenging capabilities. Strain MC277.49 was found to be the highest producer of antioxidants followed by MC108.16 and WJ11. Phenolic compounds were detected significantly in higher (p ≤ 0.05) amount succeeded by the condensed tannins and flavonoids. Total phenol content of each extract was attributed to overall antioxidant capacity. Submerged fermentation with nutritional stress conditions were found to be excellent way of producing surplus amount of natural antioxidants/secondary metabolites with their vast potential commercial application in food and pharmaceutical industries. PMID:28991177

Antioxidants Potential of the Filamentous Fungi (Mucor circinelloides).

PubMed

Hameed, Ahsan; Hussain, Syed Ammar; Yang, Junhuan; Ijaz, Muhammad Umair; Liu, Qing; Suleria, Hafiz Ansar Rasul; Song, Yuanda

2017-10-07

Three important strains of Mucor circinelloides grown in complete and minimal media for specified period (72 h, 120 h and 168 h) under submerged fermentation conditions were investigated for their potential antioxidants/secondary metabolite production. All mycelial extracts demonstrated effective antioxidant activities in terms of β-carotene/linoleic acid bleaching, radical scavenging, reduction of metal ions and chelating abilities against ferrous ions. Different extraction methods and solvent systems affected the recovery yield and antioxidant activities of the extracts significantly ( p ≤ 0.05). Ethanolic extracts were found to be rich source of antioxidant components and subsequently more effective in antioxidant properties. Fermentation period and media used also significantly affected ( p ≤ 0.05) the antioxidant production and the resulting antioxidant properties. The (ethanolic) extracts of all the strains from late exponential growth phase (120 h) showed highest antioxidant production with topmost reducing, chelating and radical scavenging capabilities. Strain MC277.49 was found to be the highest producer of antioxidants followed by MC108.16 and WJ11. Phenolic compounds were detected significantly in higher ( p ≤ 0.05) amount succeeded by the condensed tannins and flavonoids. Total phenol content of each extract was attributed to overall antioxidant capacity. Submerged fermentation with nutritional stress conditions were found to be excellent way of producing surplus amount of natural antioxidants/secondary metabolites with their vast potential commercial application in food and pharmaceutical industries.

A broad-spectrum antimicrobial activity of Bacillus subtilis RLID 12.1.

PubMed

Ramachandran, Ramya; Chalasani, Ajay Ghosh; Lal, Ram; Roy, Utpal

2014-01-01

In the present study, an attempt was made to biochemically characterize the antimicrobial substance from the soil isolate designated as RLID 12.1 and explore its potential applications in biocontrol of drug-resistant pathogens. The antimicrobial potential of the wild-type isolate belonging to the genus Bacillus was determined by the cut-well agar assay. The production of antimicrobial compound was recorded maximum at late exponential growth phase. The ultrafiltered concentrate was insensitive to organic solvents, metal salts, surfactants, and proteolytic and nonproteolytic enzymes. The concentrate was highly heat stable and active over a wide range of pH values. Partial purification, zymogram analysis, and TLC were performed to determine the preliminary biochemical nature. The molecular weight of the antimicrobial peptide was determined to be less than 2.5 kDa in 15% SDS-PAGE and in zymogram analysis against Streptococcus pyogenes. The N-terminal amino acid sequence by Edman degradation was partially determined to be T-P-P-Q-S-X-L-X-X-G, which shows very insignificant identity to other antimicrobial peptides from bacteria. The minimum inhibitory concentrations of dialysed and partially purified ion exchange fractions were determined against some selected gram-positive and gram-negative bacteria and some pathogenic yeasts. The presence of three important antimicrobial peptide biosynthesis genes ituc, fend, and bmyb was determined by PCR.

Compartment-specific pH monitoring in Bacillus subtilis using fluorescent sensor proteins: a tool to analyze the antibacterial effect of weak organic acids

PubMed Central

van Beilen, Johan W. A.; Brul, Stanley

2013-01-01

The internal pH (pHi) of a living cell is one of its most important physiological parameters. To monitor the pH inside Bacillus subtilis during various stages of its life cycle, we constructed an improved version (IpHluorin) of the ratiometric, pH-sensitive fluorescent protein pHluorin by extending it at the 5′ end with the first 24 bp of comGA. The new version, which showed an approximate 40% increase in fluorescence intensity, was expressed from developmental phase-specific, native promoters of B. subtilis that are specifically active during vegetative growth on glucose (PptsG) or during sporulation (PspoIIA, PspoIIID, and PsspE). Our results show strong, compartment-specific expression of IpHluorin that allowed accurate pHi measurements of live cultures during exponential growth, early and late sporulation, spore germination, and during subsequent spore outgrowth. Dormant spores were characterized by an pHi of 6.0 ± 0.3. Upon full germination the pHi rose dependent on the medium to 7.0–7.4. The presence of sorbic acid in the germination medium inhibited a rise in the intracellular pH of germinating spores and inhibited germination. Such effects were absent when acetic was added at identical concentrations. PMID:23785365

Physiology regulates the relationship between coccosphere geometry and growth phase in coccolithophores

NASA Astrophysics Data System (ADS)

Sheward, Rosie M.; Poulton, Alex J.; Gibbs, Samantha J.; Daniels, Chris J.; Bown, Paul R.

2017-03-01

Coccolithophores are an abundant phytoplankton group that exhibit remarkable diversity in their biology, ecology and calcitic exoskeletons (coccospheres). Their extensive fossil record is a testament to their important biogeochemical role and is a valuable archive of biotic responses to environmental change stretching back over 200 million years. However, to realise the full potential of this archive for (palaeo-)biology and biogeochemistry requires an understanding of the physiological processes that underpin coccosphere architecture. Using culturing experiments on four modern coccolithophore species (Calcidiscus leptoporus, Calcidiscus quadriperforatus, Helicosphaera carteri and Coccolithus braarudii) from three long-lived families, we investigate how coccosphere architecture responds to shifts from exponential (rapid cell division) to stationary (slowed cell division) growth phases as cell physiology reacts to nutrient depletion. These experiments reveal statistical differences in coccosphere size and the number of coccoliths per cell between these two growth phases, specifically that cells in exponential-phase growth are typically smaller with fewer coccoliths, whereas cells experiencing growth-limiting nutrient depletion have larger coccosphere sizes and greater numbers of coccoliths per cell. Although the exact numbers are species-specific, these growth-phase shifts in coccosphere geometry demonstrate that the core physiological responses of cells to nutrient depletion result in increased coccosphere sizes and coccoliths per cell across four different coccolithophore families (Calcidiscaceae, Coccolithaceae, Isochrysidaceae and Helicosphaeraceae), a representative diversity of this phytoplankton group. Building on this, the direct comparison of coccosphere geometries in modern and fossil coccolithophores enables a proxy for growth phase to be developed that can be used to investigate growth responses to environmental change throughout their long evolutionary history. Our data also show that changes in growth rate and coccoliths per cell associated with growth-phase shifts can substantially alter cellular calcite production. Coccosphere geometry is therefore a valuable tool for accessing growth information in the fossil record, providing unprecedented insights into the response of species to environmental change and the potential biogeochemical consequences.

PAH1-encoded Phosphatidate Phosphatase Plays a Role in the Growth Phase- and Inositol-mediated Regulation of Lipid Synthesis in Saccharomyces cerevisiae*

PubMed Central

Pascual, Florencia; Soto-Cardalda, Aníbal; Carman, George M.

2013-01-01

In the yeast Saccharomyces cerevisiae, the synthesis of phospholipids in the exponential phase of growth occurs at the expense of the storage lipid triacylglycerol. As exponential phase cells progress into the stationary phase, the synthesis of triacylglycerol occurs at the expense of phospholipids. Early work indicates a role of the phosphatidate phosphatase (PAP) in this metabolism; the enzyme produces the diacylglycerol needed for the synthesis of triacylglycerol and simultaneously controls the level of phosphatidate for the synthesis of phospholipids. Four genes (APP1, DPP1, LPP1, and PAH1) encode PAP activity in yeast, and it has been unclear which gene is responsible for the synthesis of triacylglycerol throughout growth. An analysis of lipid synthesis and composition, as well as PAP activity in various PAP mutant strains, showed the essential role of PAH1 in triacylglycerol synthesis throughout growth. Pah1p is a phosphorylated enzyme whose in vivo function is dependent on its dephosphorylation by the Nem1p-Spo7p protein phosphatase complex. nem1Δ mutant cells exhibited defects in triacylglycerol synthesis and lipid metabolism that mirrored those imparted by the pah1Δ mutation, substantiating the importance of Pah1p dephosphorylation throughout growth. An analysis of cells bearing PPAH1-lacZ and PPAH1-DPP1 reporter genes showed that PAH1 expression was induced throughout growth and that the induction in the stationary phase was stimulated by inositol supplementation. A mutant analysis indicated that the Ino2p/Ino4p/Opi1p regulatory circuit and transcription factors Gis1p and Rph1p mediated this regulation. PMID:24196957

Average BER of subcarrier intensity modulated free space optical systems over the exponentiated Weibull fading channels.

PubMed

Wang, Ping; Zhang, Lu; Guo, Lixin; Huang, Feng; Shang, Tao; Wang, Ranran; Yang, Yintang

2014-08-25

The average bit error rate (BER) for binary phase-shift keying (BPSK) modulation in free-space optical (FSO) links over turbulence atmosphere modeled by the exponentiated Weibull (EW) distribution is investigated in detail. The effects of aperture averaging on the average BERs for BPSK modulation under weak-to-strong turbulence conditions are studied. The average BERs of EW distribution are compared with Lognormal (LN) and Gamma-Gamma (GG) distributions in weak and strong turbulence atmosphere, respectively. The outage probability is also obtained for different turbulence strengths and receiver aperture sizes. The analytical results deduced by the generalized Gauss-Laguerre quadrature rule are verified by the Monte Carlo simulation. This work is helpful for the design of receivers for FSO communication systems.

Precipitation phase separation schemes in the Naqu River basin, eastern Tibetan plateau

NASA Astrophysics Data System (ADS)

Liu, Shaohua; Yan, Denghua; Qin, Tianling; Weng, Baisha; Lu, Yajing; Dong, Guoqiang; Gong, Boya

2018-01-01

Precipitation phase has a profound influence on the hydrological processes in the Naqu River basin, eastern Tibetan plateau. However, there are only six meteorological stations with precipitation phase (rainfall/snowfall/sleet) before 1979 within and around the basin. In order to separate snowfall from precipitation, a new separation scheme with S-shaped curve of snowfall proportion as an exponential function of daily mean temperature was developed. The determinations of critical temperatures in the single/two temperature threshold (STT/TTT2) methods were explored accordingly, and the temperature corresponding to the 50 % snowfall proportion (SP50 temperature) is an efficiently critical temperature for the STT, and two critical temperatures in TTT2 can be determined based on the exponential function and SP50 temperature. Then, different separation schemes were evaluated in separating snowfall from precipitation in the Naqu River basin. The results show that the S-shaped curve methods outperform other separation schemes. Although the STT and TTT2 slightly underestimate and overestimate the snowfall when the temperature is higher and colder than SP50 temperature respectively, the monthly and annual separation snowfalls are generally consistent with the observed snowfalls. On the whole, S-shaped curve methods, STT, and TTT2 perform well in separating snowfall from precipitation with the Pearson correlation coefficient of annual separation snowfall above 0.8 and provide possible approaches to separate the snowfall from precipitation for hydrological modelling.

Where Is ELSA? The Early to Late Shift in Aging

PubMed Central

Buchler, Norbou; Dobbins, Ian G.; Cabeza, Roberto

2012-01-01

Studies of cognitive and neural aging have recently provided evidence of a shift from an early- to late-onset cognitive control strategy, linked with temporally extended activity in the prefrontal cortex (PFC). It has been uncertain, however, whether this age-related shift is unique to PFC and executive control tasks or whether the functional location might vary depending on the particular cognitive processes that are altered. The present study tested whether an early-to-late shift in aging (ELSA) might emerge in the medial temporal lobes (MTL) during a protracted context memory task comprising both anticipatory cue (retrieval preparation) and retrieval probe (retrieval completion) phases. First, we found reduced MTL activity in older adults during the early retrieval preparation phase coupled with increased MTL activity during the late retrieval completion phase. Second, we found that functional connectivity between MTL and PFC regions was higher during retrieval preparation in young adults but higher during retrieval completion in older adults, suggesting an important interactive relationship between the ELSA pattern in MTL and PFC. Taken together, these results critically suggest that aging results in temporally lagged activity even in regions not typically associated with cognitive control, such as the MTL. PMID:22114083

Efficient full decay inversion of MRS data with a stretched-exponential approximation of the ? distribution

NASA Astrophysics Data System (ADS)

Behroozmand, Ahmad A.; Auken, Esben; Fiandaca, Gianluca; Christiansen, Anders Vest; Christensen, Niels B.

2012-08-01

We present a new, efficient and accurate forward modelling and inversion scheme for magnetic resonance sounding (MRS) data. MRS, also called surface-nuclear magnetic resonance (surface-NMR), is the only non-invasive geophysical technique that directly detects free water in the subsurface. Based on the physical principle of NMR, protons of the water molecules in the subsurface are excited at a specific frequency, and the superposition of signals from all protons within the excited earth volume is measured to estimate the subsurface water content and other hydrological parameters. In this paper, a new inversion scheme is presented in which the entire data set is used, and multi-exponential behaviour of the NMR signal is approximated by the simple stretched-exponential approach. Compared to the mono-exponential interpretation of the decaying NMR signal, we introduce a single extra parameter, the stretching exponent, which helps describe the porosity in terms of a single relaxation time parameter, and helps to determine correct initial amplitude and relaxation time of the signal. Moreover, compared to a multi-exponential interpretation of the MRS data, the decay behaviour is approximated with considerably fewer parameters. The forward response is calculated in an efficient numerical manner in terms of magnetic field calculation, discretization and integration schemes, which allows fast computation while maintaining accuracy. A piecewise linear transmitter loop is considered for electromagnetic modelling of conductivities in the layered half-space providing electromagnetic modelling of arbitrary loop shapes. The decaying signal is integrated over time windows, called gates, which increases the signal-to-noise ratio, particularly at late times, and the data vector is described with a minimum number of samples, that is, gates. The accuracy of the forward response is investigated by comparing a MRS forward response with responses from three other approaches outlining significant differences between the three approaches. All together, a full MRS forward response is calculated in about 20 s and scales so that on 10 processors the calculation time is reduced to about 3-4 s. The proposed approach is examined through synthetic data and through a field example, which demonstrate the capability of the scheme. The results of the field example agree well the information from an in-site borehole.

Late Protein Synthesis-Dependent Phases in CTA Long-Term Memory: BDNF Requirement

PubMed Central

Martínez-Moreno, Araceli; Rodríguez-Durán, Luis F.; Escobar, Martha L.

2011-01-01

It has been proposed that long-term memory (LTM) persistence requires a late protein synthesis-dependent phase, even many hours after memory acquisition. Brain-derived neurotrophic factor (BDNF) is an essential protein synthesis product that has emerged as one of the most potent molecular mediators for long-term synaptic plasticity. Studies in the rat hippocampus have been shown that BDNF is capable to rescue the late-phase of long-term potentiation as well as the hippocampus-related LTM when protein synthesis was inhibited. Our previous studies on the insular cortex (IC), a region of the temporal cortex implicated in the acquisition and storage of conditioned taste aversion (CTA), have demonstrated that intracortical delivery of BDNF reverses the deficit in CTA memory caused by the inhibition of IC protein synthesis due to anisomycin administration during early acquisition. In this work, we first analyze whether CTA memory storage is protein synthesis-dependent in different time windows. We observed that CTA memory become sensible to protein synthesis inhibition 5 and 7 h after acquisition. Then, we explore the effect of BDNF delivery (2 μg/2 μl per side) in the IC during those late protein synthesis-dependent phases. Our results show that BDNF reverses the CTA memory deficit produced by protein synthesis inhibition in both phases. These findings support the notion that recurrent rounds of consolidation-like events take place in the neocortex for maintenance of CTA memory trace and that BDNF is an essential component of these processes. PMID:21960964

Thick strings, the liquid crystal blue phase, and cosmological large-scale structure

NASA Technical Reports Server (NTRS)

Luo, Xiaochun; Schramm, David N.

1992-01-01

A phenomenological model based on the liquid crystal blue phase is proposed as a model for a late-time cosmological phase transition. Topological defects, in particular thick strings and/or domain walls, are presented as seeds for structure formation. It is shown that the observed large-scale structure, including quasi-periodic wall structure, can be well fitted in the model without violating the microwave background isotropy bound or the limits from induced gravitational waves and the millisecond pulsar timing. Furthermore, such late-time transitions can produce objects such as quasars at high redshifts. The model appears to work with either cold or hot dark matter.

Molar mass fractionation in aqueous two-phase polymer solutions of dextran and poly(ethylene glycol).

PubMed

Zhao, Ziliang; Li, Qi; Ji, Xiangling; Dimova, Rumiana; Lipowsky, Reinhard; Liu, Yonggang

2016-06-24

Dextran and poly(ethylene glycol) (PEG) in phase separated aqueous two-phase systems (ATPSs) of these two polymers, with a broad molar mass distribution for dextran and a narrow molar mass distribution for PEG, were separated and quantified by gel permeation chromatography (GPC). Tie lines constructed by GPC method are in excellent agreement with those established by the previously reported approach based on density measurements of the phases. The fractionation of dextran during phase separation of ATPS leads to the redistribution of dextran of different chain lengths between the two phases. The degree of fractionation for dextran decays exponentially as a function of chain length. The average separation parameters, for both dextran and PEG, show a crossover from mean field behavior to Ising model behavior, as the critical point is approached. Copyright © 2016 Elsevier B.V. All rights reserved.

Involvement of hippocampal cAMP/cAMP-dependent protein kinase signaling pathways in a late memory consolidation phase of aversively motivated learning in rats

PubMed Central

Bernabeu, Ramon; Bevilaqua, Lia; Ardenghi, Patricia; Bromberg, Elke; Schmitz, Paulo; Bianchin, Marino; Izquierdo, Ivan; Medina, Jorge H.

1997-01-01

cAMP/cAMP-dependent protein kinase (PKA) signaling pathway has been recently proposed to participate in both the late phase of long term potentiation in the hippocampus and in the late, protein synthesis-dependent phase of memory formation. Here we report that a late memory consolidation phase of an inhibitory avoidance learning is regulated by an hippocampal cAMP signaling pathway that is activated, at least in part, by D1/D5 receptors. Bilateral infusion of SKF 38393 (7.5 μg/side), a D1/D5 receptor agonist, into the CA1 region of the dorsal hippocampus, enhanced retention of a step-down inhibitory avoidance when given 3 or 6 h, but not immediately (0 h) or 9 h, after training. In contrast, full retrograde amnesia was obtained when SCH 23390 (0.5 μg/side), a D1/D5 receptor antagonist, was infused into the hippocampus 3 or 6 h after training. Intrahippocampal infusion of 8Br-cAMP (1.25 μg/side), or forskolin (0.5 μg/side), an activator of adenylyl cyclase, enhanced memory when given 3 or 6 h after training. KT5720 (0.5 μg/side), a specific inhibitor of PKA, hindered memory consolidation when given immediately or 3 or 6 h posttraining. Rats submitted to the avoidance task showed learning-specific increases in hippocampal 3H-SCH 23390 binding and in the endogenous levels of cAMP 3 and 6 h after training. In addition, PKA activity and P-CREB (phosphorylated form of cAMP responsive element binding protein) immunoreactivity increased in the hippocampus immediately and 3 and 6 h after training. Together, these findings suggest that the late phase of memory consolidation of an inhibitory avoidance is modulated cAMP/PKA signaling pathways in the hippocampus. PMID:9192688

Extreme late chronotypes and social jetlag challenged by Antarctic conditions in a population of university students from Uruguay

PubMed Central

Tassino, Bettina; Horta, Stefany; Santana, Noelia; Levandovski, Rosa; Silva, Ana

2016-01-01

In humans, a person’s chronotype depends on environmental cues and on individual characteristics, with late chronotypes prevailing in youth. Social jetlag (SJL), the misalignment between an individual׳s biological clock and social time, is higher in late chronotypes. Strong SJL is expected in Uruguayan university students with morning class schedules and very late entertainment activities. Sleep disorders have been reported in Antarctic inhabitants, that might be a response to the extreme environment or to the strictness of Antarctic life. We evaluated, for the first time in Uruguay, the chronotypes and SJL of 17 undergraduate students of the First Uruguayan Summer School on Antarctic Research, using Munich Chronotype Questionnaire (MCTQ) and sleep logs (SL) recorded during 3 phases: pre-Antarctic, Antarctic, and post-Antarctic. The midsleep point of free days corrected for sleep debt on work days (MSFsc,) was used as proxy of individuals’ chronotype, whose values (around 6 a.m.) are the latest ever reported. We found a SJL of around 2 h in average, which correlated positively with MSFsc, confirming that late chronotypes generate a higher sleep debt during weekdays. Midsleep point and sleep duration significantly decreased between pre-Antarctic and Antarctic phases, and sleep duration rebounded to significant higher values in the post-Antarctic phase. Waking time, but not sleep onset time, significantly varied among phases. This evidence suggests that sleep schedules more likely depended on the social agenda than on the environmental light–dark shifts. High motivation of students towards Antarctic activities likely induced a subjective perception of welfare non-dependent on sleep duration. PMID:27226819

Free energy and phase transition of the matrix model on a plane wave

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

Hadizadeh, Shirin; Ramadanovic, Bojan; Semenoff, Gordon W.

2005-03-15

It has recently been observed that the weakly coupled plane-wave matrix model has a density of states which grows exponentially at high energy. This implies that the model has a phase transition. The transition appears to be of first order. However, its exact nature is sensitive to interactions. In this paper, we analyze the effect of interactions by computing the relevant parts of the effective potential for the Polyakov loop operator in the finite temperature plane-wave matrix model to three-loop order. We show that the phase transition is indeed of first order. We also compute the correction to the Hagedornmore » temperature to order two loops.« less

Stability and phase transition of skyrmion crystals generated by Dzyaloshinskii-Moriya interaction

NASA Astrophysics Data System (ADS)

El Hog, Sahbi; Bailly-Reyre, Aurélien; Diep, H. T.

2018-06-01

We generate a crystal of skyrmions in two dimensions using a Heisenberg Hamiltonian including the ferromagnetic interaction J, the Dzyaloshinskii-Moriya interaction D, and an applied magnetic field H. The ground state (GS) is determined by minimizing the interaction energy. We show that the GS is a skyrmion crystal in a region of (D, H) . The stability of this skyrmion crystalline phase at finite temperatures is shown by a study of the time-dependence of the order parameter using Monte Carlo simulations. We observe that the relaxation is very slow and follows a stretched exponential law. The skyrmion crystal phase is shown to undergo a transition to the paramagnetic state at a finite temperature.

Quantum phases of disordered three-dimensional Majorana-Weyl fermions

NASA Astrophysics Data System (ADS)

Wilson, Justin H.; Pixley, J. H.; Goswami, Pallab; Das Sarma, S.

2017-04-01

The gapless Bogoliubov-de Gennes (BdG) quasiparticles of a clean three-dimensional spinless px+i py superconductor provide an intriguing example of a thermal Hall semimetal (ThSM) phase of Majorana-Weyl fermions; such a phase can support a large anomalous thermal Hall conductivity and protected surface Majorana-Fermi arcs at zero energy. We study the effects of quenched disorder on such a gapless topological phase by carrying out extensive numerical and analytical calculations on a lattice model for a disordered, spinless px+i py superconductor. Using the kernel polynomial method, we compute both average and typical density of states for the BdG quasiparticles, from which we construct the phase diagram of three-dimensional dirty px+i py superconductors as a function of disorder strength and chemical potential of the underlying normal state. We establish that the power law quasilocalized states induced by rare statistical fluctuations of the disorder potential give rise to an exponentially small density of states at zero energy, and even infinitesimally weak disorder converts the ThSM into a thermal diffusive Hall metal (ThDM). Consequently, the phase diagram of the disordered model only consists of ThDM and thermal insulating phases. We show the existence of two types of thermal insulators: (i) a trivial thermal band insulator (ThBI) [or BEC phase] with a smeared gap that can occur for suitable band parameters and all strengths of disorder, supporting only exponentially localized Lifshitz states (at low energy) and (ii) a thermal Anderson insulator that only exists for large disorder strengths compared to all band parameters. We determine the nature of the two distinct localization-delocalization transitions between these two types of insulators and ThDM. Additionally, we establish the scaling properties of an avoided (or hidden) quantum critical point for moderate disorder strengths, which govern the crossover between ThSM and ThDM phases over a wide range of energy scales. We also discuss the experimental relevance of our findings for three-dimensional, time reversal symmetry breaking, triplet superconducting states.

Anaphase-promoting complex/cyclosome-CDH1-mediated proteolysis of the forkhead box M1 transcription factor is critical for regulated entry into S phase.

PubMed

Park, Hyun Jung; Costa, Robert H; Lau, Lester F; Tyner, Angela L; Raychaudhuri, Pradip

2008-09-01

The forkhead box M1 (FoxM1) transcription factor is overexpressed in many cancers, and in mouse models it is required for tumor progression. FoxM1 activates expression of the cell cycle genes required for both S and M phase progression. Here we demonstrate that FoxM1 is degraded in late mitosis and early G(1) phase by the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase. FoxM1 interacts with the APC/C complex and its adaptor, Cdh1. Expression of Cdh1 stimulated degradation of the FoxM1 protein, and depletion of Cdh1 resulted in stabilization of the FoxM1 protein in late mitosis and in early G(1) phase of the cell cycle. Cdh1 has been implicated in regulating S phase entry. We show that codepletion of FoxM1 inhibits early S phase entry observed in Cdh1-depleted cells. The N-terminal region of FoxM1 contains both destruction box (D box) and KEN box sequences that are required for targeting by Cdh1. Mutation of either the D box sequence or the KEN box sequence stabilized FoxM1 and blocked Cdh1-induced proteolysis. Cells expressing a nondegradable form of FoxM1 entered S phase rapidly following release from M phase arrest. Together, our observations show that FoxM1 is one of the targets of Cdh1 in late M or early G(1) phase and that its proteolysis is important for regulated entry into S phase.

Sirtuin-2 Regulates Sepsis Inflammation in ob/ob Mice

PubMed Central

Wang, Xianfeng; Buechler, Nancy L.; Martin, Ayana; Wells, Jonathan; Yoza, Barbara; McCall, Charles E.; Vachharajani, Vidula

2016-01-01

Objective Obesity increases morbidity and resource utilization in sepsis patients. Sepsis transitions from early/hyper-inflammatory to late/hypo-inflammatory phase. Majority of sepsis-mortality occurs during the late sepsis; no therapies exist to treat late sepsis. In lean mice, we have shown that sirtuins (SIRTs) modulate this transition. Here, we investigated the role of sirtuins, especially the adipose-tissue abundant SIRT-2 on transition from early to late sepsis in obese with sepsis. Methods Sepsis was induced using cecal ligation and puncture (CLP) in ob/ob mice. We measured microvascular inflammation in response to lipopolysaccharide/normal saline re-stimulation as a “second-hit” (marker of immune function) at different time points to track phases of sepsis in ob/ob mice. We determined SIRT-2 expression during different phases of sepsis. We studied the effect of SIRT-2 inhibition during the hypo-inflammatory phase on immune function and 7-day survival. We used a RAW264.7 (RAW) cell model of sepsis for mechanistic studies. We confirmed key findings in diet induced obese (DIO) mice with sepsis. Results We observed that the ob/ob-septic mice showed an enhanced early inflammation and a persistent and prolonged hypo-inflammatory phase when compared to WT mice. Unlike WT mice that showed increased SIRT1 expression, we found that SIRT2 levels were increased in ob/ob mice during hypo-inflammation. SIRT-2 inhibition in ob/ob mice during the hypo-inflammatory phase of sepsis reversed the repressed microvascular inflammation in vivo via activation of endothelial cells and circulating leukocytes and significantly improved survival. We confirmed the key finding of the role of SIRT2 during hypo-inflammatory phase of sepsis in this project in DIO-sepsis mice. Mechanistically, in the sepsis cell model, SIRT-2 expression modulated inflammatory response by deacetylation of NFκBp65. Conclusion SIRT-2 regulates microvascular inflammation in obese mice with sepsis and may provide a novel treatment target for obesity with sepsis. PMID:27500833

Multiorgan failure in the serious trauma patient.

PubMed

Llompart-Pou, J A; Talayero, M; Homar, J; Royo, C

2014-10-01

Multiorgan failure remains one of the leading causes of late morbidity and mortality after severe trauma. In the early phase, it is related with an uncontrolled hyper-inflammation state, whereas in the late phase (>72 h), septic complications play a major role. We review the underlying pathophysiology, the evaluation with different scales and the clinical factors associated with multiorgan failure, as well as potential treatment options. Copyright © 2014 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.

Accurate Modeling of Stability and Control Properties for Fighter Aircraft from CFD

DTIC Science & Technology

2012-03-01

first an aircraft to flight test which is not until late in the design phase where millions if not billions of dollars have already been invested. It...of an aircraft and even late in the design phase there are often large gaps in data due to budget cuts to flight testing and limitations to maneuvers...early in the design cycle has been the source of many costly fixes to fighter aircraft after flight testing begins. Early prediction of these nonlinear

Mesozoic and Cenozoic structural evolution of North Oman: New insights from high-quality 3D seismic from the Lekhwair area

NASA Astrophysics Data System (ADS)

Bazalgette, Loïc; Salem, Hisham

2018-06-01

This paper highlights the role of Triassic-Jurassic extension and late Cretaceous compression in the Mesozoic-Cenozoic (Alpine) structuring of North Oman. The syn/post-Mesozoic regional structural evolution is usually documented as a succession of two stages of deformation. The Alpine 1 phase, late Cretaceous in age, occurred in association with two ophiolite obduction stages (Semail and Masirah ophiolites). It was characterised by strike slip to extensional deformation in the North Oman foreland basin sub-surface. The Alpine 2 phase, Miocene in age, was related to the continental collision responsible for both the Zagros orogen and the uplift of the Oman Mountains. The Alpine 2 deformation was transpressional to compressional. Observation and interpretation of good quality 3D seismic in the Lekhwair High area enabled the distinction of two earlier phases. Early Mesozoic extension occurred concomitantly with the regional Triassic to Jurassic rifting, developing Jurassic-age normal faults. Late Cretaceous compression occurred prior to the main Alpine 1 phase and triggered the inversion of Jurassic-seated normal faults as well as the initiation of compressional folds in the Cretaceous overburden. These early phases have been ignored or overlooked as part of the North Oman history although they are at the origin of structures hosting major local and regional hydrocarbon accumulations.

Changes of buoyant density during the S-phase of the cell cycle. Direct evidence demonstrated in acute myeloid leukemia by flowcytometry.

PubMed

Daenen, S; Huiges, W; Modderman, E; Halie, M R

1993-01-01

Studies with synchronized or exponentially growing bacteria and mammalian cell lines are not able to demonstrate small changes in buoyant density during the cell cycle. Flowcytometric analysis of density separated acute myeloid leukemia cells, a system not dependent on time-related variables, shows that the cellular buoyant density increases slightly with up to 0.008 g/ml during the S-phase, at least in cryo-preserved cells used in this study. This contrasts with the generally accepted belief that S-phase cells have a lower or constant buoyant density. A practical implication is that separation of cell (sub)populations based on differences in buoyant density could be flawed to the extent that these populations contain S-phase cells.

Two Late Pleistocene climate-driven incision/aggradation rhythms in the middle Dnieper River basin, west-central Russian Plain

NASA Astrophysics Data System (ADS)

Panin, Andrei; Adamiec, Grzegorz; Buylaert, Jan-Pieter; Matlakhova, Ekaterina; Moska, Piotr; Novenko, Elena

2017-06-01

In valleys of the River Seim and its tributaries in the middle Dnieper basin (west-central Russian Plain), two low terraces (T1, 10-16 m, and T0, 5-7 m above the river) and a floodplain (2-4 m) with characteristic large and small palaeochannels exist. A range of field and laboratory techniques was applied and ∼30 new numerical ages (OSL and 14C dates) were obtained to establish a chronology of incision and aggradation events that resulted in the current valley morphology. Two full incision/aggradation rhythms and one additional aggradation phase from the previous rhythm were recognized in the Late Pleistocene - Holocene climate cycle. The following events were detected. (1) Late MIS 5 - early MIS 4: aggradation of Terrace T1 following the deep incision at the end of MIS 6. (2) Late MIS 4 (40-30 ka): incision into Terrace T1 below the present-day river, formation of the main scarp in the bottom of the valley between Terrace T1 and Terrace T0/Floodplain levels. (3) MIS 2: aggradation of Terrace T0, lateral migrations of a shallow braided channel located few meters above the present-day river since ∼25 ka through the LGM. (4) 18-13 ka: incision into Terrace T0 below the modern river. Multiple-thread channels concentrated in a single flow that at some places formed large meanders. In the period 15-13 ka, high floods that rose above the present-day floods left large levees and overbank loams on Terrace T0. (5) Younger Dryas - Holocene transition: aggradation up to the modern channel level, transformation of large Late Glacial to small Holocene meanders. The established incision/aggradation rhythms are believed to be manifested over the Central Russian Plain outside the influence of ice sheets in the north and base level changes in the south. The two-phase deepening of the valley occurred in the last quarter of the last glacial epoch but can not be attributed directly to the glacial-interglacial transition. Both the detected incision events correspond to relatively warm climate phases - late MIS 3, post-LGM warming including the Bølling-Allerød interstadial. Anomalously large size of the preserved river palaeochannels prove that the post-LGM incision phase was induced by a climatically forced large increase of water runoff. Considerable increase of water discharges is considered the most probably cause for the late MIS 4 incision phase also. Therefore river incision seems to have been governed rather by changing water runoff that oscillated in phase shift with the thermal regime.

Spectrum analysis of radar life signal in the three kinds of theoretical models

NASA Astrophysics Data System (ADS)

Yang, X. F.; Ma, J. F.; Wang, D.

2017-02-01

In the single frequency continuous wave radar life detection system, based on the Doppler effect, the theory model of radar life signal is expressed by the real function, and there is a phenomenon that can't be confirmed by the experiment. When the phase generated by the distance between the measured object and the radar measuring head is л of integer times, the main frequency spectrum of life signal (respiration and heartbeat) is not existed in radar life signal. If this phase is л/2 of odd times, the main frequency spectrum of breath and heartbeat frequency is the strongest. In this paper, we use the Doppler effect as the basic theory, using three different mathematical expressions——real function, complex exponential function and Bessel's function expansion form. They are used to establish the theoretical model of radar life signal. Simulation analysis revealed that the Bessel expansion form theoretical model solve the problem of real function form. Compared with the theoretical model of the complex exponential function, the derived spectral line is greatly reduced in the theoretical model of Bessel expansion form, which is more consistent with the actual situation.

PBP5, PBP6 and DacD play different roles in intrinsic β-lactam resistance of Escherichia coli.

PubMed

Sarkar, Sujoy Kumar; Dutta, Mouparna; Chowdhury, Chiranjit; Kumar, Akash; Ghosh, Anindya S

2011-09-01

Escherichia coli PBP5, PBP6 and DacD, encoded by dacA, dacC and dacD, respectively, share substantial amino acid identity and together constitute ~50 % of the total penicillin-binding proteins of E. coli. PBP5 helps maintain intrinsic β-lactam resistance within the cell. To test if PBP6 and DacD play simlar roles, we deleted dacC and dacD individually, and dacC in combination with dacA, from E. coli 2443 and compared β-lactam sensitivity of the mutants and the parent strain. β-Lactam resistance was complemented by wild-type, but not dd-carboxypeptidase-deficient PBP5, confirming that enzymic activity of PBP5 is essential for β-lactam resistance. Deletion of dacC and expression of PBP6 during exponential or stationary phase did not alter β-lactam resistance of a dacA mutant. Expression of DacD during mid-exponential phase partially restored β-lactam resistance of the dacA mutant. Therefore, PBP5 dd-carboxypeptidase activity is essential for intrinsic β-lactam resistance of E. coli and DacD can partially compensate for PBP5 in this capacity, whereas PBP6 cannot.

Strain, curvature, and twist measurements in digital holographic interferometry using pseudo-Wigner-Ville distribution based method

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

Rajshekhar, G.; Gorthi, Sai Siva; Rastogi, Pramod

2009-09-15

Measurement of strain, curvature, and twist of a deformed object play an important role in deformation analysis. Strain depends on the first order displacement derivative, whereas curvature and twist are determined by second order displacement derivatives. This paper proposes a pseudo-Wigner-Ville distribution based method for measurement of strain, curvature, and twist in digital holographic interferometry where the object deformation or displacement is encoded as interference phase. In the proposed method, the phase derivative is estimated by peak detection of pseudo-Wigner-Ville distribution evaluated along each row/column of the reconstructed interference field. A complex exponential signal with unit amplitude and the phasemore » derivative estimate as the argument is then generated and the pseudo-Wigner-Ville distribution along each row/column of this signal is evaluated. The curvature is estimated by using peak tracking strategy for the new distribution. For estimation of twist, the pseudo-Wigner-Ville distribution is evaluated along each column/row (i.e., in alternate direction with respect to the previous one) for the generated complex exponential signal and the corresponding peak detection gives the twist estimate.« less

Post-invasion demography of prehistoric humans in South America.

PubMed

Goldberg, Amy; Mychajliw, Alexis M; Hadly, Elizabeth A

2016-04-14

As the last habitable continent colonized by humans, the site of multiple domestication hotspots, and the location of the largest Pleistocene megafaunal extinction, South America is central to human prehistory. Yet remarkably little is known about human population dynamics during colonization, subsequent expansions, and domestication. Here we reconstruct the spatiotemporal patterns of human population growth in South America using a newly aggregated database of 1,147 archaeological sites and 5,464 calibrated radiocarbon dates spanning fourteen thousand to two thousand years ago (ka). We demonstrate that, rather than a steady exponential expansion, the demographic history of South Americans is characterized by two distinct phases. First, humans spread rapidly throughout the continent, but remained at low population sizes for 8,000 years, including a 4,000-year period of 'boom-and-bust' oscillations with no net growth. Supplementation of hunting with domesticated crops and animals had a minimal impact on population carrying capacity. Only with widespread sedentism, beginning ~5 ka, did a second demographic phase begin, with evidence for exponential population growth in cultural hotspots, characteristic of the Neolithic transition worldwide. The unique extent of humanity's ability to modify its environment to markedly increase carrying capacity in South America is therefore an unexpectedly recent phenomenon.

Exponential increase in the on-off ratio of conductance in organic memory devices by controlling the surface morphology of the devices

NASA Astrophysics Data System (ADS)

Vyas, Giriraj; Dagar, Parveen; Sahu, Satyajit

2018-05-01

We have shown an exponential increase in the ratio of conductance in the on and off states of switching devices by controlling the surface morphology of the thin films for the device by depositing at different rotational speeds. The pinholes which are preferred topography on the surface at higher rotational speed give rise to higher on-off ratio of current from the devices fabricated at the speed. The lower rotational speed contributes to higher thickness of the film and hence no switching. For thicker films, the domain is formed due to phase segregation between the two components in the film, which also indicates that the film is far from thermal equilibrium. At higher speed, there is very little scope of segregation when the film is drying up. Hence, there are only few pinholes on the surface of the film which are shallow. So, the filamentary mechanism of switching in memory devices can be firmly established by varying the speed of thin film deposition which leads to phase segregation of the materials. Thus, the formation of filament can be regulated by controlling the thickness and the surface morphology.

Ruthenium trisbipyridine as a candidate for gas-phase spectroscopic studies in a Fourier transform mass spectrometer

DOE PAGES

Scott, Jill R.; Ham, Jason E.; Durham, Bill; ...

2004-01-01

Metal polypyridines are excellent candidates for gas-phase optical experiments where their intrinsic properties can be studied without complications due to the presence of solvent. The fluorescence lifetimes of [Ru(bpy) 3 ] 1+ trapped in an optical detection cell within a Fourier transform mass spectrometer were obtained using matrix-assisted laser desorption/ionization to generate the ions with either 2,5-dihydroxybenzoic acid (DHB) or sinapinic acid (SA) as matrix. All transients acquired, whether using DHB or SA for ion generation, were best described as approximately exponential decays. The rate constant for transients derived using DHB as matrix was 4×10 7 s −1 , whilemore » the rate constant using SA was 1×10 7 s −1 . Some suggestions of multiple exponential decay were evident although limited by the quality of the signals. Photodissociation experiments revealed that [Ru(bpy) 3 ] 1+ generated using DHB can decompose to [Ru(bpy) 2 ] 1+ , whereas ions generated using SA showed no decomposition. Comparison of the mass spectra with the fluorescence lifetimes illustrates the promise of incorporating optical detection with trapped ion mass spectrometry techniques.« less

Current therapy for laser-induced retinal injury: overview of clinical and experimental approaches

NASA Astrophysics Data System (ADS)

Schuschereba, Steven T.; Scales, David K.

1997-05-01

Adequate treatment strategies do not exist for retinal laser injuries. To gain a better understanding of available treatments, data form a variety of human laser accident cases and relevant experimental work was evaluated. Most laser eye injury cases are not attended by an ophthalmologist for several hours to days after injury and most patients are not treated.Of the few cases receiving treatment; only the FDA approved glucocortocoids are available for use. Their use, however, is still controversial. Experimental animal work during the acute phase of injury indicates that productive efforts have targeted neuroprotection, inflammation, ischemia- reperfusion, and lipid peroxidation. Late stage issues for treatment are scarring, retinal hole persistence and expansion, and traction. In summary, treatments for acute and late phase injury are currently inadequate. Preserving existing neural elements should be the top priority in these injuries. We recommend that relevant treatments begin immediately after injury. Other approaches are necessary to target early and late phase secondary damage events that are entrenched.

The Extent to Which Dayside Reconnection Drives Field-Aligned Currents During Substorms

NASA Astrophysics Data System (ADS)

Forsyth, C.; Shortt, M. W.; Coxon, J.; Rae, J.; Freeman, M. P.; Kalmoni, N. M. E.; Jackman, C. M.; Anderson, B. J.

2016-12-01

Field-aligned currents, also known as Birkeland currents, are the agents by which energy and momentum is transferred to the ionosphere from the magnetosphere and solar wind. In order to understand this coupling, it is necessary to analyze the variations in these current systems with respect to the main energy sources of the solar wind and substorms. In this study, we perform a superposed epoch analysis of field-aligned currents determined by the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) project with respect to substorm expansion phase onsets identified using the Substorm Onsets and Phases from Indices of the Electrojet (SOPHIE) technique. We examine the total upward and downward currents separately in the noon, dusk, dawn and midnight sectors. Our results show that the dusk and dawn currents have up to a 66% linear correlated with the dayside reconnection rate estimated from solar wind measurements, whereas the noon and midnight currents are not. The noon currents show little or no variation throughout the substorm cycle. The midnight currents follows the dusk currents up to 20 min before onset, after which the midnight current increases more rapidly and exponentially. At substorm onset, the exponential growth rate increases. While the midnight field-aligned currents grow exponentially after substorm onset, the auroral indices vary with a 1/6th power law. Overall, our results show that the growth and decay rates of the Region 1 and 2 current systems, which are strongest at dawn and dusk, are directly driven by the solar wind, whereas the growth and decay rates of the substorm current system, which are dominant at midnight, act independently of the upstream driver.

On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid ^4{He}

NASA Astrophysics Data System (ADS)

Niemetz, M.; Hänninen, R.; Schoepe, W.

2017-05-01

The flow of superfluid ^4{He} around a translationally oscillating sphere, levitating without mechanical support, can either be laminar or turbulent, depending on the velocity amplitude. Below a critical velocity v_c that scales as ω ^{1/2} and is temperature independent below 1 K, the flow is laminar (potential flow). Below 0.5 K, the linear drag force is caused by ballistic phonon scattering that vanishes as T^4 until background damping, measured in the empty cell, becomes dominant for T < 0.1 K. Increasing the velocity amplitude above v_c leads to a transition from potential flow to turbulence, where the large turbulent drag force varies as (v^2 - v_c^2). In a small velocity interval Δ v {/} v_c ≤ 3% above v_c, the flow is unstable below 0.5 K, switching intermittently between both patterns. From time series recorded at constant temperature and driving force, the lifetimes of both phases are analyzed statistically. We observe metastable states of potential flow which, after a mean lifetime of 25 min, ultimately break down due to vorticity created by natural background radioactivity. The lifetimes of the turbulent phases have an exponential distribution, and the mean increases exponentially with Δ v^2. We investigate the frequency at which the vortex rings are shed from the sphere. Our results are compared with recent data of other authors on vortex shedding by moving a laser beam through a Bose-Einstein condensate. Finally, we show that our observed transition to turbulence belongs to the class of "supertransient chaos" where lifetimes of the turbulent states increase faster than exponentially.

Sleep and Premenstrual Syndrome

PubMed Central

Jehan, Shazia; Auguste, Evan; Hussain, Mahjabeen; Pandi-Perumal, Seithikurippu R.; Brzezinski, Amon; Gupta, Ravi; Attarian, Hrayr; Jean-Louis, Giradin; McFarlane, Samy I.

2016-01-01

The etiology of premenstrual syndrome (PMS) is unknown; it may be due to the normal effect of hormones during the menstrual cycle as it occurs in the late luteal phase of the menstrual cycle.PMS affects women of childbearing age and remits with the onset of menstruation. The menstrual phase is known to influence stage 2 and REM sleep in women, irrespective of premenstrual dysphoric disorder (PMDD). Women with PMDD showed a decreased response to melatonin in their luteal phase as compared to the follicular phase of the menstrual cycle. However, melatonin duration or timing of offset in the morning has not been reported to correlate with the mood. Rather, improvement in mood-related symptoms of PMDD has been found to be influenced by sleep deprivation, be it sleep restrictions in early or late night. Sleep disturbance and decreased melatonin secretions due to hormonal fluctuations during the luteal phase of the menstrual cycle could explain the sleep complaints of PMDD. PMID:28239684

Strategies of Nitrosomonas europaea 19718 to counter low dissolved oxygen and high nitrite concentrations.

PubMed

Yu, Ran; Chandran, Kartik

2010-03-04

Nitrosomonas europaea is a widely studied chemolithoautotrophic ammonia oxidizing bacterium. While significant work exists on the ammonia oxidation pathway of N. europaea, its responses to factors such as dissolved oxygen limitation or sufficiency or exposure to high nitrite concentrations, particularly at the functional gene transcription level are relatively sparse. The principal goal of this study was to investigate responses at the whole-cell activity and gene transcript levels in N. europaea 19718 batch cultures, which were cultivated at different dissolved oxygen and nitrite concentrations. Transcription of genes coding for principal metabolic pathways including ammonia oxidation (amoA), hydroxylamine oxidation (hao), nitrite reduction (nirK) and nitric oxide reduction (norB) were quantitatively measured during batch growth, at a range of DO concentrations (0.5, 1.5 and 3.0 mg O2/L). Measurements were also conducted during growth at 1.5 mg O2/L in the presence of 280 mg-N/L of externally added nitrite. Several wide ranging responses to DO limitation and nitrite toxicity were observed in N. europaea batch cultures. In contrast to our initial hypothesis, exponential phase mRNA concentrations of both amoA and hao increased with decreasing DO concentrations, suggesting a mechanism to metabolize ammonia and hydroxylamine more effectively under DO limitation. Batch growth in the presence of 280 mg nitrite-N/L resulted in elevated exponential phase nirK and norB mRNA concentrations, potentially to promote utilization of nitrite as an electron acceptor and to detoxify nitrite. This response was in keeping with our initial hypothesis and congruent with similar responses in heterotrophic denitrifying bacteria. Stationary phase responses were distinct from exponential phase responses in most cases, suggesting a strong impact of ammonia availability and metabolism on responses to DO limitation and nitrite toxicity. In general, whole-cell responses to DO limitation or nitrite toxicity, such as sOUR or nitrite reduction to nitric oxide (NO) did not parallel the corresponding mRNA (nirK) profiles, suggesting differences between the gene transcription and enzyme translation or activity levels. The results of this study show that N. europaea possesses specific mechanisms to cope with growth under low DO concentrations and high nitrite concentrations. These mechanisms are additionally influenced by the physiological growth state of N. europaea cultures and are possibly geared to enable more efficient substrate utilization or nitrite detoxification.

Extracellular ATP mediates the late phase of neutrophil recruitment to the lung in murine models of acute lung injury.

PubMed

Shah, Dilip; Romero, Freddy; Stafstrom, William; Duong, Michelle; Summer, Ross

2014-01-01

Acute lung injury (ALI) is a severe inflammatory condition whose pathogenesis is irrevocably linked to neutrophil emigration to the lung. Activation and recruitment of neutrophils to the lung is mostly attributable to local production of the chemokines. However, much of our understanding of neutrophil recruitment to the lung is based on studies focusing on early time points after initiation of injury. In this study, we sought to evaluate the extended temporal relationship between neutrophil chemotactic factor expression and influx of neutrophils into the lung after intratracheal administration of either LPS or bleomycin. In both models, results demonstrated two phases of neutrophil chemotactic factor expression; first, an early phase characterized by high levels of CXCL1/keratinocyte-derived chemokine, CXCL2/monocyte-inhibitory protein-2, and CXCL5/LPS-induced chemokine expression, and second, a late phase distinguished by increases in extracellular ATP. Furthermore, we show that strategies aimed at either enhancing ATP catabolism (ip ecto-5'-nucleotidase administration) or inhibiting glycolytic ATP production (ip 2-deoxy-d-glucose treatment) reduce extracellular ATP accumulation, limit vascular leakage, and effectively block the late, but not the early, stages of neutrophil recruitment to the lung after LPS instillation. In conclusion, this study illustrates that neutrophil recruitment to the lung is mediated by the time-dependent expression of chemotactic factors and suggests that novel strategies, which reduce extracellular ATP accumulation, may attenuate late neutrophil recruitment and limit lung injury during ALI.

Extracellular ATP mediates the late phase of neutrophil recruitment to the lung in murine models of acute lung injury

PubMed Central

Shah, Dilip; Romero, Freddy; Stafstrom, William; Duong, Michelle

2013-01-01

Acute lung injury (ALI) is a severe inflammatory condition whose pathogenesis is irrevocably linked to neutrophil emigration to the lung. Activation and recruitment of neutrophils to the lung is mostly attributable to local production of the chemokines. However, much of our understanding of neutrophil recruitment to the lung is based on studies focusing on early time points after initiation of injury. In this study, we sought to evaluate the extended temporal relationship between neutrophil chemotactic factor expression and influx of neutrophils into the lung after intratracheal administration of either LPS or bleomycin. In both models, results demonstrated two phases of neutrophil chemotactic factor expression; first, an early phase characterized by high levels of CXCL1/keratinocyte-derived chemokine, CXCL2/monocyte-inhibitory protein-2, and CXCL5/LPS-induced chemokine expression, and second, a late phase distinguished by increases in extracellular ATP. Furthermore, we show that strategies aimed at either enhancing ATP catabolism (ip ecto-5′-nucleotidase administration) or inhibiting glycolytic ATP production (ip 2-deoxy-d-glucose treatment) reduce extracellular ATP accumulation, limit vascular leakage, and effectively block the late, but not the early, stages of neutrophil recruitment to the lung after LPS instillation. In conclusion, this study illustrates that neutrophil recruitment to the lung is mediated by the time-dependent expression of chemotactic factors and suggests that novel strategies, which reduce extracellular ATP accumulation, may attenuate late neutrophil recruitment and limit lung injury during ALI. PMID:24285266

Anaphase-Promoting Complex/Cyclosome-Cdh1-Mediated Proteolysis of the Forkhead Box M1 Transcription Factor Is Critical for Regulated Entry into S Phase▿

PubMed Central

Park, Hyun Jung; Costa, Robert H.; Lau, Lester F.; Tyner, Angela L.; Raychaudhuri, Pradip

2008-01-01

The forkhead box M1 (FoxM1) transcription factor is overexpressed in many cancers, and in mouse models it is required for tumor progression. FoxM1 activates expression of the cell cycle genes required for both S and M phase progression. Here we demonstrate that FoxM1 is degraded in late mitosis and early G1 phase by the anaphase-promoting complex/cyclosome (APC/C) E3 ubiquitin ligase. FoxM1 interacts with the APC/C complex and its adaptor, Cdh1. Expression of Cdh1 stimulated degradation of the FoxM1 protein, and depletion of Cdh1 resulted in stabilization of the FoxM1 protein in late mitosis and in early G1 phase of the cell cycle. Cdh1 has been implicated in regulating S phase entry. We show that codepletion of FoxM1 inhibits early S phase entry observed in Cdh1-depleted cells. The N-terminal region of FoxM1 contains both destruction box (D box) and KEN box sequences that are required for targeting by Cdh1. Mutation of either the D box sequence or the KEN box sequence stabilized FoxM1 and blocked Cdh1-induced proteolysis. Cells expressing a nondegradable form of FoxM1 entered S phase rapidly following release from M phase arrest. Together, our observations show that FoxM1 is one of the targets of Cdh1 in late M or early G1 phase and that its proteolysis is important for regulated entry into S phase. PMID:18573889

The use of lipids as phase change materials for thermal energy storage

USDA-ARS?s Scientific Manuscript database

Phase change materials (PCMs) are substances capable of absorbing and releasing large 2 amounts of thermal energy (heat or cold) as latent heat over constant temperature as they 3 undergo a change in state of matter (phase transition), commonly, between solid and 4 liquid phases. Since the late 194...

15-digit accuracy calculations of Ambartsumian-Chandrasekhar's H-functions for four-term phase functions with the double-exponential formula

NASA Astrophysics Data System (ADS)

Kawabata, Kiyoshi

2018-01-01

We have established an iterative scheme to calculate with 15-digit accuracy the numerical values of Ambartsumian-Chandrasekhar's H-functions for anisotropic scattering characterized by the four-term phase function: the method incorporates some advantageous features of the iterative procedure of Kawabata (Astrophys. Space Sci. 358:32, 2015) and the double-exponential integration formula (DE-formula) of Takahashi and Mori (Publ. Res. Inst. Math. Sci. Kyoto Univ. 9:721, 1974), which proved highly effective in Kawabata (Astrophys. Space Sci. 361:373, 2016). Actual calculations of the H-functions have been carried out employing 27 selected cases of the phase function, 56 values of the single scattering albedo π0, and 36 values of an angular variable μ(= cosθ), with θ being the zenith angle specifying the direction of incidence and/or emergence of radiation. Partial results obtained for conservative isotropic scattering, Rayleigh scattering, and anisotropic scattering due to a full four-term phase function are presented. They indicate that it is important to simultaneously verify accuracy of the numerical values of the H-functions for μ<0.05, the domain often neglected in tabulation. As a sample application of the isotropic scattering H-function, an attempt is made in Appendix to simulate by iteratively solving the Ambartsumian equation the values of the plane and spherical albedos of a semi-infinite, homogeneous atmosphere calculated by Rogovtsov and Borovik (J. Quant. Spectrosc. Radiat. Transf. 183:128, 2016), who employed their analytical representations for these quantities and the single-term and two-term Henyey-Greenstein phase functions of appreciably high degrees of anisotropy. While our results are in satisfactory agreement with theirs, our procedure is in need of a faster algorithm to routinely deal with problems involving highly anisotropic phase functions giving rise to near-conservative scattering.

Effects of Lactobacillus plantarum Strain OLL2712 Culture Conditions on the Anti-inflammatory Activities for Murine Immune Cells and Obese and Type 2 Diabetic Mice.

PubMed

Toshimitsu, T; Ozaki, S; Mochizuki, J; Furuichi, K; Asami, Y

2017-04-01

Studies on the health-promoting effects of lactic acid bacteria (LAB) are numerous, but few provide examples of the relationship between LAB function and culture conditions. We verified the effect of differences in culture conditions on Lactobacillus plantarum OLL2712 functionality; this strain exhibits anti-inflammatory activity and preventive effects against metabolic disorders. We measured interleukin-10 (IL-10) and IL-12 production in murine immune cells treated with OLL2712 cells prepared under various culture conditions. The results showed that the IL-10-inducing activities of OLL2712 cells on murine immune cells differed dramatically between OLL2712 groups at different culture phases and using different culture medium components, temperatures, and neutralizing pHs. In particular, exponential-phase cells had much more IL-10-inducing activity than stationary-phase cells. We confirmed that the Toll-like receptor 2 (TLR2) stimulation activity of OLL2712 cells depended on culture conditions in conjunction with IL-10-inducing activity. We also demonstrated functional differences by culture phases in vivo ; OLL2712 cells at exponential phase had more anti-inflammatory activity and anti-metabolic-disorder effects on obese and diabetic mice than those by their stationary-phase counterparts. These results suggest that culture conditions affect the functionality of anti-inflammatory LAB. IMPORTANCE While previous studies demonstrated that culture conditions affected the immunomodulatory properties of lactic acid bacteria (LAB), few have comprehensively investigated the relationship between culture conditions and LAB functionality. In this study, we demonstrated several culture conditions of Lactobacillus plantarum OLL2712 for higher anti-inflammatory activity. We also showed that culture conditions concretely influenced the health-promoting functions of OLL2712 in vivo , particularly against metabolic disorders. Further, we characterized a novel mechanism by which changing LAB culture conditions affected immunomodulatory properties. Our results suggest that culture condition optimization is important for the production of LAB with anti-inflammatory activity. Copyright © 2017 American Society for Microbiology.

Evidence for a Dual Antiviral Role of the Major Nuclear Domain 10 Component Sp100 during the Immediate-Early and Late Phases of the Human Cytomegalovirus Replication Cycle ▿

PubMed Central

Tavalai, Nina; Adler, Martina; Scherer, Myriam; Riedl, Yvonne; Stamminger, Thomas

2011-01-01

In recent studies, the nuclear domain 10 (ND10) components PML and hDaxx were identified as cellular restriction factors that inhibit the initiation of human cytomegalovirus (HCMV) replication. The antiviral function of ND10, however, is antagonized by the IE1 protein, which induces ND10 disruption. Here we show that IE1 not only de-SUMOylates PML immediately upon infection but also directly targets Sp100. IE1 expression alone was sufficient to downregulate endogenous Sp100 independently of the presence of PML. Moreover, cotransfection experiments revealed that IE1 negatively interferes with the SUMOylation of all Sp100 isoforms. The modulation of Sp100 at immediate-early (IE) times of infection, indeed, seemed to have an in vivo relevance for HCMV replication, since knockdown of Sp100 resulted in more cells initiating the viral gene expression program. In addition, we observed that Sp100 was degraded in a proteasome-dependent manner at late times postinfection, suggesting that Sp100 may play an additional antiviral role during the late phase. Infection experiments conducted with Sp100 knockdown human foreskin fibroblasts (HFFs) confirmed this hypothesis: depletion of Sp100 resulted in augmented release of progeny virus particles compared to that from control cells. Consistent with this observation, we noted increased amounts of viral late gene products in the absence of Sp100. Importantly, this elevated late gene expression was not dependent on enhanced viral IE gene expression. Taken together, our data provide evidence that Sp100 is the first ND10-related factor identified that not only possesses the potential to restrict the initial stage of infection but also inhibits HCMV replication during the late phase. PMID:21734036

Preexposure to ozone blocks the antigen-induced late asthmatic response of the canine peripheral airways

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

Turner, C.R.; Kleeberger, S.R.; Spannhake, E.W.

1989-01-01

The influence of exposure of the airways to ozone on acute allergic responsiveness has been investigated in several species. Little is known, however, about the effect of this environmental pollutant on the late asthmatic response (LAR) in animals in which it is exhibited. The purpose of this study was to evaluate this effect in the canine peripheral airways and to assess the potential role of mast cells in modulating the effect. A series of experiments on seven mongrel dogs demonstrated that the numbers of mast cells at the base of the epithelial region of small subsegmental airways exposed to 1more » ppm ozone for 5 min were significantly (p less than .01) increased 3 h following exposure compared to air exposed or nonexposed control airways. In a second series of experiments performed on eight additional mongrel dogs with inherent sensitivity to Ascaris suum antigen, antigen aerosol was administered to the sublobar segment 3 h following ozone preexposure when mast cell numbers were presumed to be increased. These experiments were performed to determine whether ozone preexposure could enhance the late-phase response to antigen by virtue of acutely increasing the number of mast cells available to bind the antigen. Four of the eight dogs tested displayed a late-phase response to antigen following air-sham preexposure. In these four dogs, simultaneous ozone preexposure of a contralateral lobe completely blocked the late-phase response to antigen. These results indicate that the consequences of a single exposure to ozone persist beyond its effects on acute antigen-induced bronchoconstriction and extend to the complex processes involved with the late response. This attenuating effect of ozone is seen under conditions where mast-cell numbers in the airways are increased above baseline levels.« less

Dynamical analysis for a scalar-tensor model with kinetic and nonminimal couplings

NASA Astrophysics Data System (ADS)

Granda, L. N.; Jimenez, D. F.

We study the autonomous system for a scalar-tensor model of dark energy with nonminimal coupling to curvature and nonminimal kinetic coupling to the Einstein tensor. The critical points describe important stable asymptotic scenarios including quintessence, phantom and de Sitter attractor solutions. Two functional forms for the coupling functions and the scalar potential were considered: power-law and exponential functions of the scalar field. For power-law couplings, the restrictions on stable quintessence and phantom solutions lead to asymptotic freedom regime for the gravitational interaction. For the exponential functions, the stable quintessence, phantom or de Sitter solutions allow asymptotic behaviors where the effective Newtonian coupling can reach either the asymptotic freedom regime or constant value. The phantom solutions could be realized without appealing to ghost degrees of freedom. Transient inflationary and radiation dominated phases can also be described.

Cosmological models constructed by van der Waals fluid approximation and volumetric expansion

NASA Astrophysics Data System (ADS)

Samanta, G. C.; Myrzakulov, R.

The universe modeled with van der Waals fluid approximation, where the van der Waals fluid equation of state contains a single parameter ωv. Analytical solutions to the Einstein’s field equations are obtained by assuming the mean scale factor of the metric follows volumetric exponential and power-law expansions. The model describes a rapid expansion where the acceleration grows in an exponential way and the van der Waals fluid behaves like an inflation for an initial epoch of the universe. Also, the model describes that when time goes away the acceleration is positive, but it decreases to zero and the van der Waals fluid approximation behaves like a present accelerated phase of the universe. Finally, it is observed that the model contains a type-III future singularity for volumetric power-law expansion.

Lithium diffusion in polyether ether ketone and polyimide stimulated by in situ electron irradiation and studied by the neutron depth profiling method

NASA Astrophysics Data System (ADS)

Vacik, J.; Hnatowicz, V.; Attar, F. M. D.; Mathakari, N. L.; Dahiwale, S. S.; Dhole, S. D.; Bhoraskar, V. N.

2014-10-01

Diffusion of lithium from a LiCl aqueous solution into polyether ether ketone (PEEK) and polyimide (PI) assisted by in situ irradiation with 6.5 MeV electrons was studied by the neutron depth profiling method. The number of the Li atoms was found to be roughly proportional to the diffusion time. Regardless of the diffusion time, the measured depth profiles in PEEK exhibit a nearly exponential form, indicating achievement of a steady-state phase of a diffusion-reaction process specified in the text. The form of the profiles in PI is more complex and it depends strongly on the diffusion time. For the longer diffusion time, the profile consists of near-surface bell-shaped part due to Fickian-like diffusion and deeper exponential part.

Bloch-Nordsieck thermometers: one-loop exponentiation in finite temperature QED

NASA Astrophysics Data System (ADS)

Gupta, Sourendu; Indumathi, D.; Mathews, Prakash; Ravindran, V.

1996-02-01

We study the scattering of hard external particles in a heat bath in a real-time formalism for finite temperature QED. We investigate the distribution of the 4-momentum difference of initial and final hard particles in a fully covariant manner when the scale of the process, Q, is much larger than the temperature, T. Our computations are valid for all T subject to this constraint. We exponentiate the leading infra-red term at one-loop order through a resummation of soft (thermal) photon emissions and absorptions. For T > 0, we find that tensor structures arise which are not present at T = 0. These cant' thermal signatures. As a result, external particles can serve as thermometers introduced into the heat bath. We investigate the phase space origin of log( Q/ m) and log ( Q/ T) teens.

Flow induced crystallisation of penetrable particles

NASA Astrophysics Data System (ADS)

Scacchi, Alberto; Brader, Joseph M.

2018-03-01

For a system of Brownian particles interacting via a soft exponential potential we investigate the interaction between equilibrium crystallisation and spatially varying shear flow. For thermodynamic state points within the liquid part of the phase diagram, but close to the crystallisation phase boundary, we observe that imposing a Poiseuille flow can induce nonequilibrium crystalline ordering in regions of low shear gradient. The physical mechanism responsible for this phenomenon is shear-induced particle migration, which causes particles to drift preferentially towards the center of the flow channel, thus increasing the local density in the channel center. The method employed is classical dynamical density functional theory.

Flow induced crystallisation of penetrable particles.

PubMed

Scacchi, Alberto; Brader, Joseph M

2018-03-07

For a system of Brownian particles interacting via a soft exponential potential we investigate the interaction between equilibrium crystallisation and spatially varying shear flow. For thermodynamic state points within the liquid part of the phase diagram, but close to the crystallisation phase boundary, we observe that imposing a Poiseuille flow can induce nonequilibrium crystalline ordering in regions of low shear gradient. The physical mechanism responsible for this phenomenon is shear-induced particle migration, which causes particles to drift preferentially towards the center of the flow channel, thus increasing the local density in the channel center. The method employed is classical dynamical density functional theory.

Characteristics of time-activity curves obtained from dynamic 11C-methionine PET in common primary brain tumors.

PubMed

Nomura, Yuichi; Asano, Yoshitaka; Shinoda, Jun; Yano, Hirohito; Ikegame, Yuka; Kawasaki, Tomohiro; Nakayama, Noriyuki; Maruyama, Takashi; Muragaki, Yoshihiro; Iwama, Toru

2018-07-01

The aim of this study was to assess whether dynamic PET with 11 C-methionine (MET) (MET-PET) is useful in the diagnosis of brain tumors. One hundred sixty patients with brain tumors (139 gliomas, 9 meningiomas, 4 hemangioblastomas and 8 primary central nervous system lymphomas [PCNSL]) underwent dynamic MET-PET with a 3-dimensional acquisition mode, and the maximum tumor MET-standardized uptake value (MET-SUV) was measured consecutively to construct a time-activity curve (TAC). Furthermore, receiver operating characteristic (ROC) curves were generated from the time-to-peak (TTP) and the slope of the curve in the late phase (SLOPE). The TAC patterns of MET-SUVs (MET-TACs) could be divided into four characteristic types when MET dynamics were analyzed by dividing the MET-TAC into three phases. MET-SUVs were significantly higher in early and late phases in glioblastoma compared to anaplastic astrocytoma, diffuse astrocytoma and the normal frontal cortex (P < 0.05). The SLOPE in the late phase was significantly lower in tumors that included an oligodendroglial component compared to astrocytic tumors (P < 0.001). When we set the cutoff of the SLOPE in the late phase to - 0.04 h -1 for the differentiation of tumors that included an oligodendroglial component from astrocytic tumors, the diagnostic accuracy was 74.2% sensitivity and 64.9% specificity. The area under the ROC curve was 0.731. The results of this study show that quantification of the MET-TAC for each brain tumor identified by a dynamic MET-PET study could be helpful in the non-invasive discrimination of brain tumor subtypes, in particular gliomas.

Nuclear Translocation of MEK1 Triggers a Complex T cell Response through the Co-repressor Silencing Mediator of Retinoid and Thyroid Hormone Receptor (SMRT)

PubMed Central

Guo, Lei; Chen, Chaoyu; Liang, Qiaoling; Karim, Md. Zunayet; Gorska, Magdalena M.; Alam, Rafeul

2012-01-01

MEK1 phosphorylates ERK1/2 and regulates T cell generation, differentiation and function. MEK1 has recently been shown to translocate to the nucleus. Its nuclear function is largely unknown. By studying human CD4 T cells we demonstrate that a low level of MEK1 is present in the nucleus of CD4 T cells under basal conditions. T cell activation further increases the nuclear translocation of MEK1. MEK1 interacts with the nuclear receptor co-repressor SMRT. MEK1 reduces the nuclear level of SMRT in an activation-dependent manner. MEK1 is recruited to the promoter of c-Fos upon TCR stimulation. Conversely, SMRT is bound to the c-Fos promoter under basal conditions and is removed upon TCR stimulation. We examined the role of SMRT in regulation of T cell function. siRNA-mediated knockdown of SMRT results in a biphasic effect on cytokine production. The production of the cytokines—IL2, IL4, IL10 and IFNγ increases in the early phase (8 hr) and then decreases in the late phase (48 hr). The late phase decrease is associated with inhibition of T cell proliferation. The late phase inhibition of T cell activation is, in part, mediated by IL10 that is produced in the early phase, and in part, by β-catenin signaling. Thus, we have identified a novel nuclear function of MEK1. MEK1 triggers a complex pattern of early T cell activation followed by a late inhibition through its interaction with SMRT. This biphasic dual effect likely reflects a homeostatic regulation of T cell function by MEK1. PMID:23225884

Relationship between ADAMTS13 activity, von Willebrand factor antigen levels and platelet function in the early and late phases after TIA or ischaemic stroke.

PubMed

McCabe, Dominick J H; Murphy, Stephen J X; Starke, Richard; Harrison, Paul; Brown, Martin M; Sidhu, Paul S; Mackie, Ian J; Scully, Marie; Machin, Samuel J

2015-01-15

Reduced ADAMTS13 activity is seen in thrombotic thrombocytopenic purpura (TTP), and may lead to accumulation of prothrombotic ultra-large von Willebrand factor (ULVWF) multimers in vivo. ADAMTS13 activity and its relationship with VWF antigen (VWF:Ag) levels and platelet function in 'non-TTP related' TIA or ischaemic stroke has not been comprehensively studied. In this prospective pilot observational analytical case-control study, ADAMTS13 activity and VWF:Ag levels were quantified in platelet poor plasma in 53 patients in the early phase (≤ 4 weeks) and 34 of these patients in the late phase (≥ 3 months) after TIA or ischaemic stroke on aspirin. Data were compared with those from 22 controls not on aspirin. The impact of ADAMTS13 on platelet function in whole blood was quantified by measuring Collagen-ADP (C-ADP) and Collagen-Epinephrine closure times on a platelet function analyser (PFA-100(®)). Median ADAMTS13 activity was significantly reduced in the early phase (71.96% vs. 95.5%, P <0.01) but not in the late phase after TIA or stroke compared with controls (86.3% vs. 95.5%, P=0.19). There was a significant inverse relationship between ADAMTS13 activity and VWF:Ag levels in the early phase (r=-0.31; P=0.024), but not in the late phase after TIA or stroke (P=0.74). There was a positive correlation between ADAMTS13 activity and C-ADP closure times in early phase patients only, likely mediated via VWF:Ag levels. ADAMTS13 activity is reduced and VWF:Ag expression is increased within 4 weeks of TIA or ischaemic stroke onset, and can promote enhanced platelet adhesion and aggregation in response to stimulation with collagen and ADP via VWF-mediated pathways. These data improve our understanding of the dynamic haemostatic and thrombotic profiles of ischaemic cerebrovascular disease (CVD) patients, and are important in view of the potential future role that ADAMTS13 may have to play as an anti-thrombotic agent in CVD. Copyright © 2014 Elsevier B.V. All rights reserved.

Immuno-histochemical localization of LH-RH during different phases of estrus cycle of rat, with reference to the preoptic and arcuate neurons, and the ependymal cells.

PubMed

Naik, D V

1976-10-06

Immunohistochemical localization of luteinizing hormone-releasing hormone (LH-RH), during different phases of the estrus cycle, in the preoptic, suprachiasmatic and arcuate nuclei, and in the OVLT of rats, with special emphasis on the ependymal cells, was studied by light, fluorescent and electron microscopy, by using rabbit anti serum to synthetic LH-RH. The LH-RH neurons in the above mentioned areas, were very active during late diestrus and early proestrus phases. Specialized ependymal cells bordering the 3rd ventricle also showed varied LH-RH positive reaction during different phases of the estrus cycle. Immunofluorescent studies showed cyclic variations in the LH-RH material in the CSF of the preoptic and infundibular recesses, as well as in the 3rd ventricle near OVLT, in that, it was maximum during late diestrus and early proestrus phases. Immediately after this, the LH-RH late proestrus was reached. We have also observed that during the proestrus phase, as the LH-RH material started declining in the CSF, it had started building up in the specialized ependyma. Estrus, metaestrus and early diestrus phases showed very weak immunofluorescent LH-RH material in the lumen of the infundibular recess and in the specialized ependyma. Our immuno-electron microscopic observations showed pleomorphic LH-RH granules in the specialized ependyma during late kiestrus and proestrus phases. All these observations lead us to believe that LH-RH is not synthesized in the ependymal cells,but is phagocytosed from the CSF of the 3rd ventricle by the specialized ependyma, which transports it to the ME portal system. In males, the fluorescent LH-RH material did not show any noticeable changes. With the present and previous work,it is concluded that the neurons in differentnuclei synthesize LH-RH and transport it to the ME portal system,primarily through the nerve fibers and secondarily by the ventricular route. It is also suggested that the ependymal transport of LH-RH to the ME portal system is cyclic and thus controls the gonadotropin secretion.

Taking the brakes off the learning curve.

PubMed

Gheysen, Freja; Lasne, Gabriel; Pélégrini-Issac, Mélanie; Albouy, Genevieve; Meunier, Sabine; Benali, Habib; Doyon, Julien; Popa, Traian

2017-03-01

Motor learning is characterized by patterns of cerebello-striato-cortical activations shifting in time, yet the early dynamic and function of these activations remains unclear. Five groups of subjects underwent either continuous or intermittent theta-burst stimulation of one cerebellar hemisphere, or no stimulation just before learning a new motor sequence during fMRI scanning. We identified three phases during initial learning: one rapid, one slow, and one quasi-asymptotic performance phase. These phases were not changed by left cerebellar stimulation. Right cerebellar inhibition, however, accelerated learning and enhanced brain activation in critical motor learning-related areas during the first phase, continuing with reduced brain activation but high-performance in late phase. Right cerebellar excitation did not affect the early learning process, but slowed learning significantly in late phase, along with increased brain activation. We conclude that the right cerebellum is a key factor coordinating other neuronal loops in the early acquisition of an explicit motor sequential skill. Hum Brain Mapp 38:1676-1691, 2017. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Prethermal Phases of Matter Protected by Time-Translation Symmetry

NASA Astrophysics Data System (ADS)

Else, Dominic V.; Bauer, Bela; Nayak, Chetan

2017-01-01

In a periodically driven (Floquet) system, there is the possibility for new phases of matter, not present in stationary systems, protected by discrete time-translation symmetry. This includes topological phases protected in part by time-translation symmetry, as well as phases distinguished by the spontaneous breaking of this symmetry, dubbed "Floquet time crystals." We show that such phases of matter can exist in the prethermal regime of periodically driven systems, which exists generically for sufficiently large drive frequency, thereby eliminating the need for integrability or strong quenched disorder, which limited previous constructions. We prove a theorem that states that such a prethermal regime persists until times that are nearly exponentially long in the ratio of certain couplings to the drive frequency. By similar techniques, we can also construct stationary systems that spontaneously break continuous time-translation symmetry. Furthermore, we argue that for driven systems coupled to a cold bath, the prethermal regime could potentially persist to infinite time.

Learning phase transitions by confusion

NASA Astrophysics Data System (ADS)

van Nieuwenburg, Evert; Liu, Ye-Hua; Huber, Sebastian

Classifying phases of matter is a central problem in physics. For quantum mechanical systems, this task can be daunting owing to the exponentially large Hilbert space. Thanks to the available computing power and access to ever larger data sets, classification problems are now routinely solved using machine learning techniques. Here, we propose to use a neural network based approach to find transitions depending on the performance of the neural network after training it with deliberately incorrectly labelled data. We demonstrate the success of this method on the topological phase transition in the Kitaev chain, the thermal phase transition in the classical Ising model, and the many-body-localization transition in a disordered quantum spin chain. Our method does not depend on order parameters, knowledge of the topological content of the phases, or any other specifics of the transition at hand. It therefore paves the way to a generic tool to identify unexplored transitions.

The hyper-fluorescent transitional bands in ultra-late phase of indocyanine green angiography in chronic central serous chorioretinopathy.

PubMed

Hua, Rui; Yao, Kai; Xia, Fan; Li, Jun; Guo, Lei; Yang, Guoxing; Tao, Jun

2016-03-01

Chronic central serous chorioretinopathy (CSCR) is regarded as a type of severe diffuse retinal pigment epitheliopathy. There is an atrophic tract at level of retinal pigment epithelium (RPE) due to hyper-permeability of choroidal vessels, along with photoreceptor (PR) atrophy. Indocyanine green angiography (ICGA) is considered a gold standard for diagnosis. The purpose of this work is to investigate the hyper-fluorescent transitional bands (HFTB) between hypo-fluorescent and normal regions of the retina in the ultra-late phase of ICGA in CSCR. 26 chronic CSCR eyes and 12 relative normal eyes received spectral domain optical coherence tomography (SD-OCT), and ICGA at the 24th hour after indocyanine green (ICG) intravenous injection. In the ultra-late phase, images showed homogenous fluorescence in all normal eyes. On the contrary, geographical hypofluorescent lesions with atrophy of RPE was noted in 26 chronic CSCR eyes. Moreover, HFTB with intact RPE and disrupted PR was detected in 20 out of 26 chronic CSCR eyes (76.9%). The HFTB may indicate the early damage in chronic CSCR. Ultra-late ICGA can monitor not only metabolic status by endogenous melanin, but also membrane function in RPE by exogenous ICG molecule. © 2015 Wiley Periodicals, Inc.

Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination

PubMed Central

2013-01-01

Background In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza-like illness (ILI) among the target groups for vaccination in Spain in the 2011–2012 season. We also studied influenza VE in the early (weeks 52/2011-7/2012) and late (weeks 8-14/2012) phases of the epidemic and according to time since vaccination. Methods Medically attended patients with ILI were systematically swabbed to collect information on exposure, laboratory outcome and confounding factors. Patients belonging to target groups for vaccination and who were swabbed <8 days after symptom onset were included. Cases tested positive for influenza and controls tested negative for any influenza virus. To examine the effect of a late season, analyses were performed according to the phase of the season and according to the time between vaccination and symptoms onset. Results The overall adjusted influenza VE against A(H3N2) was 45% (95% CI, 0–69). The estimated influenza VE was 52% (95% CI, -3 to 78), 40% (95% CI, -40 to 74) and 22% (95% CI, -135 to 74) at 3.5 months, 3.5-4 months, and >4 months, respectively, since vaccination. A decrease in VE with time since vaccination was only observed in individuals aged ≥ 65 years. Regarding the phase of the season, decreasing point estimates were only observed in the early phase, whereas very low or null estimates were obtained in the late phase for the shortest time interval. Conclusions The 2011–2012 influenza vaccine showed a low-to-moderate protective effect against medically attended, laboratory-confirmed influenza in the target groups for vaccination, in a late season and with a limited match between the vaccine and circulating strains. The suggested decrease in influenza VE with time since vaccination was mostly observed in the elderly population. The decreasing protective effect of the vaccine in the late part of the season could be related to waning vaccine protection because no viral changes were identified throughout the season. PMID:24053661

Molecular dynamics study of the isotropic-nematic quench.

PubMed

Bradac, Z; Kralj, S; Zumer, S

2002-02-01

Effects of cylindrical and spherical confinement on the kinetics of the isotropic-nematic quench is studied numerically. The nematic liquid crystal structure was modeled by a modified induced-dipole--induced-dipole interaction. Molecules were allowed to wander around points of a hexagonal lattice. Brownian molecular dynamics was used in order to access macroscopic time scales. In the bulk we distinguish between the early, domain, and late stage regime. The early regime is characterized by the exponential growth of the nematic uniaxial order parameter. In the domain regime domains are clearly visible and the average nematic domain size xi(d) obeys the dynamical scaling law xi(d)-t(gamma). The late stage evolution is dominated by dynamics of individual defects. In a confined system the qualitative change of the scaling behavior appears when xi(d) becomes comparable to a typical linear dimension R of the confinement. In the confining regime (xi(d)>or=R) the scaling coefficient gamma depends on the details of the confinement and also the final equilibrium nematic structure. The domain growth is well described with the Kibble-Zurek mechanism.

Neuroimaging Evidence of Cerebellar Involvement in Premenstrual Dysphoric Disorder

PubMed Central

Rapkin, Andrea J.; Berman, Steven M.; Mandelkern, Mark A.; Silverman, Daniel H. S.; Morgan, Melinda; London, Edythe D.

2010-01-01

Background Premenstrual dysphoric disorder (PMDD) is a debilitating cyclic disorder that is characterized by affective symptoms, including irritability, depression, and anxiety which arise in the luteal phase of the menstrual cycle and resolve soon after the onset of menses. Despite a prevalence of up to 8% in women of reproductive age, few studies have investigated the brain mechanisms that underlie this disorder. Methods We used positron emission tomography with [18F] fluorodeoxyglucose and self-report questionnaires to assess cerebral glucose metabolism and mood in 12 women with PMDD and 12 healthy comparison subjects in the follicular and late luteal phases of the menstrual cycle. The primary biological endpoint was incorporated regional cerebral radioactivity (scaled to the global mean) as an index of glucose metabolism. Relationships between regional brain activity and mood ratings were assessed. Blood samples were taken before each session for assay of plasma estradiol and progesterone concentrations. Results There were no group differences in hormone levels in either the follicular or late luteal phase, but the groups differed in the effect of menstrual phase on cerebellar activity. Women with PMDD, but not comparison subjects, showed an increase in cerebellar activity (particularly in the right cerebellar vermis) from the follicular phase to the late luteal phase (p = 0.003). In the PMDD group, this increase in cerebellar activity was correlated with worsening of mood (p = 0.018). Conclusions These findings suggest that the midline cerebellar nuclei, which have been implicated in other mood disorders, also contribute to negative mood in PMDD. PMID:21092938

Presence of novel compound BCR-ABL mutations in late chronic and advanced phase imatinib sensitive CML patients indicates their possible role in CML progression.

PubMed

Akram, Afia Muhammad; Iqbal, Zafar; Akhtar, Tanveer; Khalid, Ahmed Mukhtar; Sabar, Muhammad Farooq; Qazi, Mahmood Hussain; Aziz, Zeba; Sajid, Nadia; Aleem, Aamer; Rasool, Mahmood; Asif, Muhammad; Aloraibi, Saleh; Aljamaan, Khaled; Iqbal, Mudassar

2017-04-03

BCR-ABL kinase domain (K D ) mutations are well known for causing resistance against tyrosine kinase inhibitors (TKIs) and disease progression in chronic myeloid leukemia (CML). In recent years, compound BCR-ABL mutations have emerged as a new threat to CML patients by causing higher degrees of resistance involving multiple TKIs, including ponatinib. However, there are limited reports about association of compound BCR-ABL mutations with disease progression in imatinib (IM) sensitive CML patients. Therefore, we investigated presence of ABL-K D mutations in chronic phase (n = 41), late chronic phase (n = 33) and accelerated phase (n = 16) imatinib responders. Direct sequencing analysis was used for this purpose. Eleven patients (12.22%) in late-CP CML were detected having total 24 types of point mutations, out of which 8 (72.72%) harbored compound mutated sites. SH2 contact site mutations were dominant in our study cohort, with E355G (3.33%) being the most prevalent. Five patients (45%) all having compound mutated sites, progressed to advanced phases of disease during follow up studies. Two novel silent mutations G208G and E292E/E were detected in combination with other mutants, indicating limited tolerance for BCR-ABL1 kinase domain for missense mutations. However, no patient in early CP of disease manifested mutated ABL-K D . Occurrence of mutations was found associated with elevated platelet count (p = 0.037) and patients of male sex (p = 0.049). The median overall survival and event free survival of CML patients (n = 90) was 6.98 and 5.8 y respectively. The compound missense mutations in BCR-ABL kinase domain responsible to elicit disease progression, drug resistance or disease relapse in CML, can be present in yet Imatinib sensitive patients. Disease progression observed here, emphasizes the need of ABL-K D mutation screening in late chronic phase CML patients for improved clinical management of disease.

Modification of 5-methoxy-N,N-dimethyltryptamine-induced hyperactivity by monoamine oxidase A inhibitor harmaline in mice and the underlying serotonergic mechanisms.

PubMed

Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

2016-06-01

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are indolealkylamine (IAA) drugs often abused together. Our recent studies have revealed the significant effects of co-administered harmaline, a monoamine oxidase inhibitor (MAOI), on 5-MeO-DMT pharmacokinetics and thermoregulation. This study was to delineate the impact of harmaline and 5-MeO-DMT on home-cage activity in mouse models, as well as the contribution of serotonin (5-HT) receptors. Home-cage activities of individual animals were monitored automatically in the home cages following implantation of telemetry transmitters and administration of various doses of IAA drugs and 5-HT receptor antagonists. Area under the effect curve (AUEC) of mouse activity values were calculated by trapezoidal rule. High dose of harmaline (15mg/kg, ip) alone caused an early-phase (0-45min) hypoactivity in mice that was fully attenuated by 5-HT1A receptor antagonist WAY-100635, whereas a late-phase (45-180min) hyperactivity that was reduced by 5-HT2A receptor antagonist MDL-100907. 5-MeO-DMT (10 and 20mg/kg, ip) alone induced biphasic effects, an early-phase (0-45min) hypoactivity that was completely attenuated by WAY-100635, and a late-phase (45-180min) hyperactivity that was fully suppressed by MDL-100907. Interestingly, co-administration of MAOI harmaline (2-15mg/kg) with a subthreshold dose of 5-MeO-DMT (2mg/kg) induced excessive hyperactivities at late phase (45-180min) that could be abolished by either WAY-100635 or MDL-100907. Co-administration of MAOI with 5-MeO-DMT provokes excessive late-phase hyperactivity, which involves the activation of both 5-HT1A and 5-HT2A receptors. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Modification of 5-methoxy-N,N-dimethyltryptamine-induced hyperactivity by monoamine oxidase A inhibitor harmaline in mice and the underlying serotonergic mechanisms

PubMed Central

Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

2016-01-01

Background 5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are indolealkylamine (IAA) drugs often abused together. Our recent studies have revealed the significant effects of co-administered harmaline, a monoamine oxidase inhibitor (MAOI), on 5-MeO-DMT pharmacokinetics and thermoregulation. This study was to delineate the impact of harmaline and 5-MeO-DMT on home-cage activity in mouse models, as well as the contribution of serotonin (5-HT) receptors. Methods Home-cage activities of individual animals were monitored automatically in the home cages following implantation of telemetry transmitters and administration of various doses of IAA drugs and 5-HT receptor antagonists. Area under the effect curve (AUEC) of mouse activity values were calculated by trapezoidal rule. Results High dose of harmaline (15 mg/kg, ip) alone caused an early-phase (0–45 min) hypoactivity in mice that was fully attenuated by 5-HT1A receptor antagonist WAY-100635, whereas a late-phase (45–180 min) hyperactivity that was reduced by 5-HT2A receptor antagonist MDL-100907. 5-MeO-DMT (10 and 20 mg/kg, ip) alone induced biphasic effects, an early-phase (0–45 min) hypoactivity that was completely attenuated by WAY-100635, and a late-phase (45–180 min) hyperactivity that was fully suppressed by MDL-100907. Interestingly, co-administration of MAOI harmaline (2–15 mg/kg) with a subthreshold dose of 5-MeO-DMT (2 mg/kg) induced excessive hyperactivities at late phase (45–180 min) that could be abolished by either WAY-100635 or MDL-100907. Conclusions Co-administration of MAOI with 5-MeO-DMT provokes excessive late-phase hyperactivity, which involves the activation of both 5-HT1A and 5-HT2A receptors. PMID:26977821

Parity-Time Symmetry Breaking in Spin Chains.

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

Galda, Alexey; Vinokur, Valerii M.

We investigate nonequilibrium phase transitions in classical Heisenberg spin chains associated with spontaneous breaking of parity-time (PT) symmetry of the system under the action of Slonczewski spin-transfer torque (STT) modeled by an applied imaginary magnetic field. We reveal the STT-driven PT symmetry-breaking phase transition between the regimes of precessional and exponentially damped spin dynamics and show that its several properties can be derived from the distribution of zeros of the system's partition function, the approach first introduced by Yang and Lee for studying equilibrium phase transitions in Ising spin chains. The physical interpretation of imaginary magnetic field as describing themore » action of nonconservative forces opens the possibility of direct observations of Lee-Yang zeros in nonequilibrium physical systems.« less

Parity-time symmetry breaking in spin chains

NASA Astrophysics Data System (ADS)

Galda, Alexey; Vinokur, Valerii M.

2018-05-01

We investigate nonequilibrium phase transitions in classical Heisenberg spin chains associated with spontaneous breaking of parity-time (PT ) symmetry of the system under the action of Slonczewski spin-transfer torque (STT) modeled by an applied imaginary magnetic field. We reveal the STT-driven PT symmetry-breaking phase transition between the regimes of precessional and exponentially damped spin dynamics and show that its several properties can be derived from the distribution of zeros of the system's partition function, the approach first introduced by Yang and Lee for studying equilibrium phase transitions in Ising spin chains. The physical interpretation of imaginary magnetic field as describing the action of nonconservative forces opens the possibility of direct observations of Lee-Yang zeros in nonequilibrium physical systems.

[Peculiarities of growth of the monocellular green algae culture after the influence of electromagnetic field in deuterated water-containing media].

PubMed

Semenov, K T; Aslanian, R R

2013-01-01

Exposing the inoculum of monocellular green algae Dunalialla tertiolecta and Tetraselmis viridis to 50 Hz electromagnetic field for several hours resulted in a reduced growth rate in both cultures. It was ascertained that heavy water inhibited growth of algae Dunaliella tertiolecta. The light water activated growth of the culture in the exponential phase only.

Peroxide resistance in Escherichia coli serotype O157:H7 biofilms is regulated by both RpoS dependent and independent mechanisms

USDA-ARS?s Scientific Manuscript database

In many Escherichia coli serotype O157:H7 strains, defenses against peroxide damage include the peroxiredoxin AhpCF and three catalases: KatG (catalase-peroxidase), KatE (catalase), and the plasmid-encoded KatP (catalase/peroxidase). AhpC, KatG, and KatP are induced by OxyR /s70 in exponential phase...

Production of lactate and acetate by Lactobacillus coryniformis subsp. torquens DSM 20004(T) in comparison with Lactobacillus amylovorus DSM 20531(T).

PubMed

Slavica, Anita; Trontel, Antonija; Jelovac, Nuša; Kosovec, Željka; Šantek, Božidar; Novak, Srđan

2015-05-20

Lactobacillus coryniformis subsp. torquens DSM20004(T) is a d-lactate producer, with a portion of the d-lactate higher than 99.9% of total lactic acid produced. Acetate was identified as the second end-product that appeared at the end of the exponential growth phase in MRS medium when glucose concentration dropped to 38.41mM (6.92g/L). The acetate production was prolonged to the stationary phase, while the concentration of d-lactate remained constant. Other end-products were not identified by HPLC method. The known metabolic pathways of glucose fermentation in lactic acid bacteria do not produce the particular combination of these two end-products, but besides lactate and acetate also formate, ethanol and CO2 are produced. For comparison, the production of lactate and acetate by a d-/l-lactate producer Lactobacillus amylovorus DSM 20531(T) was also investigated. This strain produced equimolar quantities of d- and l-lactate in the MRS medium. Acetate was produced only when initial concentration of glucose was 55.51mM (10g/L) and production started in the exponential phase when concentration of glucose dropped to 35.52mM (6.40g/L). Similar behavior was observed with the initial concentration of maltose of 29.21mM (10g/L). An unstructured mathematical model was established for the bioprocess simulation. Copyright © 2015 Elsevier B.V. All rights reserved.

Numerical solution of non-linear dual-phase-lag bioheat transfer equation within skin tissues.

PubMed

Kumar, Dinesh; Kumar, P; Rai, K N

2017-11-01

This paper deals with numerical modeling and simulation of heat transfer in skin tissues using non-linear dual-phase-lag (DPL) bioheat transfer model under periodic heat flux boundary condition. The blood perfusion is assumed temperature-dependent which results in non-linear DPL bioheat transfer model in order to predict more accurate results. A numerical method of line which is based on finite difference and Runge-Kutta (4,5) schemes, is used to solve the present non-linear problem. Under specific case, the exact solution has been obtained and compared with the present numerical scheme, and we found that those are in good agreement. A comparison based on model selection criterion (AIC) has been made among non-linear DPL models when the variation of blood perfusion rate with temperature is of constant, linear and exponential type with the experimental data and it has been found that non-linear DPL model with exponential variation of blood perfusion rate is closest to the experimental data. In addition, it is found that due to absence of phase-lag phenomena in Pennes bioheat transfer model, it achieves steady state more quickly and always predict higher temperature than thermal and DPL non-linear models. The effect of coefficient of blood perfusion rate, dimensionless heating frequency and Kirchoff number on dimensionless temperature distribution has also been analyzed. The whole analysis is presented in dimensionless form. Copyright © 2017 Elsevier Inc. All rights reserved.

Serum levels of inhibin A and inhibin B in women with normal and abnormal luteal function.

PubMed

Yamoto, M; Imai, M; Otani, H; Nakano, R

1997-05-01

To determine whether serum inhibin A and inhibin B concentrations are lower in patients with luteal dysfunction than in women with normal luteal function. Serum samples were collected from seven healthy women with regular menstrual cycles. Serum samples on days +5 to +9 after the LH surge were collected from patients with luteal dysfunction. The diagnosis of luteal dysfunction was based on a luteal phase duration less than 11 days and a single midluteal progesterone level below 10 ng/mL. Serum levels of inhibin A, inhibin B, progesterone, estradiol (E2), FSH, and LH were measured. The serum inhibin A levels were increased toward the late follicular phase. The levels reached a maximum during the midluteal phase, followed by a fall during the late luteal phase. The serum inhibin B levels were high during the follicular phases and the early luteal phase. The levels decreased during the midluteal and late luteal phases. Serum levels (mean +/- standard error of the mean) of inhibin A in patients with luteal dysfunction were significantly lower than those in women during the midluteal phase (26.2 +/- 2.9 compared to 41.9 +/- 2.8 pg/mL; P < .01) in addition to the expected decrease in serum progesterone levels (6.3 +/- 0.7 compared to 14.7 +/- 1.2 ng/mL; P < .01). Serum inhibin B levels did not differ significantly between normal women and those with luteal dysfunction. There also were no significant differences in the E2, FSH, and LH levels. Levels of inhibin A, but not of inhibin B, may reflect the human luteal function.

Change in Photosystem II Photochemistry During Algal Growth Phases of Chlorella vulgaris and Scenedesmus obliquus.

PubMed

Oukarroum, Abdallah

2016-06-01

Sensitivity of photosynthetic processes towards environmental stress is used as a bioanalytical tool to evaluate the responses of aquatic plants to a changing environment. In this paper, change of biomass density, chlorophyll a fluorescence and photosynthetic parameters during growth phases of two microalgae Chlorella vulgaris and Scenedesmus obliquus were studied. The photosynthetic growth behaviour changed significantly with cell age and algae species. During the exponential phase of growth, the photosynthesis capacity reached its maximum and decreased in ageing algal culture during stationary phase. In conclusion, the chlorophyll a fluorescence OJIP method and the derived fluorescence parameters would be an accurate method for obtaining information on maximum photosynthetic capacities and monitoring algal cell growth. This will contribute to more understanding, for example, of toxic actions of pollutants in microalgae test.

Differential role of afferent and efferent renal nerves in the maintenance of early- and late-phase Dahl S hypertension

PubMed Central

Foss, Jason D.; Fink, Gregory D.

2015-01-01

Clinical data suggest that renal denervation (RDNX) may be an effective treatment for human hypertension; however, it is unclear whether this therapeutic effect is due to ablation of afferent or efferent renal nerves. We have previously shown that RDNX lowers arterial pressure in hypertensive Dahl salt-sensitive (S) rats to a similar degree observed in clinical trials. In addition, we have recently developed a method for selective ablation of afferent renal nerves (renal-CAP). In the present study, we tested the hypothesis that the antihypertensive effect of RDNX in the Dahl S rat is due to ablation of afferent renal nerves by comparing the effect of complete RDNX to renal-CAP during two phases of hypertension in the Dahl S rat. In the early phase, rats underwent treatment after 3 wk of high-NaCl feeding when mean arterial pressure (MAP) was ∼140 mmHg. In the late phase, rats underwent treatment after 9 wk of high NaCl feeding, when MAP was ∼170 mmHg. RDNX reduced MAP ∼10 mmHg compared with sham surgery in both the early and late phase, whereas renal-CAP had no antihypertensive effect. These results suggest that, in the Dahl S rat, the antihypertensive effect of RDNX is not dependent on pretreatment arterial pressure, nor is it due to ablation of afferent renal nerves. PMID:26661098

Analysis of the temporal program of replication initiation in yeast chromosomes.

PubMed

Friedman, K L; Raghuraman, M K; Fangman, W L; Brewer, B J

1995-01-01

The multiple origins of eukaryotic chromosomes vary in the time of their initiation during S phase. In the chromosomes of Saccharomyces cerevisiae the presence of a functional telomere causes nearby origins to delay initiation until the second half of S phase. The key feature of telomeres that causes the replication delay is the telomeric sequence (C(1-3)A/G(1-3)T) itself and not the proximity of the origin to a DNA end. A second group of late replicating origins has been found at an internal position on chromosome XIV. Four origins, spanning approximately 140 kb, initiate replication in the second half of S phase. At least two of these internal origins maintain their late replication time on circular plasmids. Each of these origins can be separated into two functional elements: those sequences that provide origin function and those that impose late activation. Because the assay for determining replication time is costly and laborious, it has not been possible to analyze in detail these 'late' elements. We report here the development of two new assays for determining replication time. The first exploits the expression of the Escherichia coli dam methylase in yeast and the characteristic period of hemimethylation that transiently follows the passage of a replication fork. The second uses quantitative hybridization to detect two-fold differences in the amount of specific restriction fragments as a function of progress through S phase. The novel aspect of this assay is the creation in vivo of a non-replicating DNA sequence by site-specific pop-out recombination. This non-replicating fragment acts as an internal control for copy number within and between samples. Both of these techniques are rapid and much less costly than the more conventional density transfer experiments that require CsCl gradients to detect replicated DNA. With these techniques it should be possible to identify the sequences responsible for late initiation, to search for other late replicating regions in the genome, and to begin to analyze the effect that altering the temporal program has on chromosome function.

Valorization of lubricant-based wastewater for bacterial neutral lipids production: Growth-linked biosynthesis.

PubMed

Da Silva, Pedro D M P; Lima, Filipa; Alves, Maria Madalena; Bijmans, Martijn F M; Pereira, Maria Alcina

2016-09-15

Lipids produced by microorganisms are currently of great interest as raw material for either biofuels or oleochemicals production. Significant biosynthesis of neutral lipids, such as triacylglycerol (TAG) and wax esters (WE) are thought to be limited to a few strains. Hydrocarbonoclastic bacteria (HCB), key players in bioremediation of hydrocarbon contaminated ecosystems, are among this group of strains. Hydrocarbon rich wastewaters have been overlooked concerning their potential as raw material for microbial lipids production. In this study, lubricant-based wastewater was fed, as sole carbon source, to two HCB representative wild strains: Alcanivorax borkumensis SK2, and Rhodococcus opacus PD630. Neutral lipid production was observed with both strains cultivated under uncontrolled conditions of pH and dissolved oxygen. A. borkumensis SK2 was further investigated in a pH- and OD-controlled fermenter. Different phases were assessed separately in terms of lipids production and alkanes removal. The maximum TAG production rate occurred during stationary phase (4 mg-TAG/L h). The maximum production rate of WE-like compounds was 15 mg/L h, and was observed during exponential growth phase. Hydrocarbons removal was 97% of the gas chromatography (GC) resolved straight-chain alkanes. The maximum removal rate was observed during exponential growth phase (6 mg-alkanes/L h). This investigation proposes a novel approach for the management of lubricant waste oil, aiming at its conversion into valuable lipids. The feasibility of the concept is demonstrated under low salt (0.3%) and saline (3.3%) conditions, and presents clues for its technological development, since growth associated oil production opens the possibility for establishing continuous fermentation processes. Copyright © 2016 Elsevier Ltd. All rights reserved.

Characterization of phosphatidic acid phosphatase activity in the oleaginous yeast Yarrowia lipolytica and its role in lipid biosynthesis.

PubMed

Hardman, Derell; McFalls, Daniel; Fakas, Stylianos

2017-02-01

Phosphatidic acid phosphatase (PAP) catalyses the committed step of triacylglycerol (TAG) biosynthesis and thus regulates the amounts of TAG produced by the cell. TAG is the target of biotechnological processes developed for the production of food lipids or biofuels. These processes are using oleaginous microorganisms like the yeast Yarrowia lipolytica as the TAG producers. Thus manipulating key enzymatic activities like PAP in Y. lipolytica could drive lipid biosynthesis towards TAG production and increase TAG yields. In this study, PAP activity in Y. lipolytica was characterized in detail and its role in lipid biosynthesis was addressed. PAP activity increased 2.5-fold with the addition of Mg 2+ (1 mm) in the assay mixture, which means that most of the PAP activity was due to Mg 2+ -dependent PAP enzymes (e.g. Pah1, App1). In contrast, N-ethylmaleimide (NEM) potently inhibited PAP activity, indicating the presence of NEM-sensitive PAP enzymes (e.g. App1, Lpp1). Localization studies revealed that the majority of PAP activity resides in the membrane fraction, while the cytosolic fraction harbours only a small amount of activity. PAP activity was regulated in a growth-dependent manner, being induced at the early exponential phase and declining thereafter. PAP activity did not correlate with TAG synthesis, which increased as cells progressed from the exponential phase to the early stationary phase. In stationary phase, TAG was mobilized with the concomitant synthesis of sterols and sterol esters. These results provide the first insights into the role of PAP in lipid biosynthesis by Y. lipolytica. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Flocculation in ale brewing strains of Saccharomyces cerevisiae: re-evaluation of the role of cell surface charge and hydrophobicity.

PubMed

Holle, Ann Van; Machado, Manuela D; Soares, Eduardo V

2012-02-01

Flocculation is an eco-friendly process of cell separation, which has been traditionally exploited by the brewing industry. Cell surface charge (CSC), cell surface hydrophobicity (CSH) and the presence of active flocculins, during the growth of two (NCYC 1195 and NCYC 1214) ale brewing flocculent strains, belonging to the NewFlo phenotype, were examined. Ale strains, in exponential phase of growth, were not flocculent and did not present active flocculent lectins on the cell surface; in contrast, the same strains, in stationary phase of growth, were highly flocculent (>98%) and presented a hydrophobicity of approximately three to seven times higher than in exponential phase. No relationship between growth phase, flocculation and CSC was observed. For comparative purposes, a constitutively flocculent strain (S646-1B) and its isogenic non-flocculent strain (S646-8D) were also used. The treatment of ale brewing and S646-1B strains with pronase E originated a loss of flocculation and a strong reduction of CSH; S646-1B pronase E-treated cells displayed a similar CSH as the non-treated S646-8D cells. The treatment of the S646-8D strain with protease did not reduce CSH. In conclusion, the increase of CSH observed at the onset of flocculation of ale strains is a consequence of the presence of flocculins on the yeast cell surface and not the cause of yeast flocculation. CSH and CSC play a minor role in the auto-aggregation of the ale strains since the degree of flocculation is defined, primarily, by the presence of active flocculins on the yeast cell wall.

The Decompression Sickness and Venous Gas Emboli Consequences of Air Breaks During 100% Oxygen Prebreathe

NASA Technical Reports Server (NTRS)

Conkin, J.; Gernhardt, M. L.; Powell, M. R.

2004-01-01

Not enough is known about the increased risk of hypobaric decompression sickness (DCS) and production of venous (VGE) and arterial (AGE) gas emboli following an air break in an otherwise normal 100% resting oxygen (O2) prebreathe (PB), and certainly a break in PB when exercise is used to accelerate nitrogen (N2) elimination from the tissues. Current Aeromedical Flight Rules at the Johnson Space Center about additional PB payback times are untested, possibly too conservative, and therefore not optimized for operational use. A 10 min air break at 90 min into a 120 min PB that includes initial dual-cycle ergometry for 10 min will show a measurable increase in the risk of DCS and VGE after ascent to 4.3 psia compared to a 10 min break at 15 min into the PB, or when there is no break in PB. Data collection with humans begins in 2005, but here we first evaluate the hypothesis using three models of tissue N2 kinetics: Model I is a simple single half-time compartment exponential model, Model II is a three compartment half-time exponential model, and Model III is a variable half-time compartment model where the percentage of maximum O2 consumption for the subject during dual-cycle ergometry exercise defines the half-time compartment. Model I with large rate constants to simulate an exercise effect always showed a late break in PB had the greatest consequence. Model II showed an early break had the greatest consequence. Model III showed there was no difference between early or late break in exercise PB. Only one of these outcomes will be observed when humans are tested. Our results will favor one of these models, and so advance our understanding of tissue N2 kinetics, and of altitude DCS after an air break in PB.

The effects of a rhythm and music-based therapy program and therapeutic riding in late recovery phase following stroke: a study protocol for a three-armed randomized controlled trial

PubMed Central

2012-01-01

Background Stroke represents one of the most costly and long-term disabling conditions in adulthood worldwide and there is a need to determine the effectiveness of rehabilitation programs in the late phase after stroke. Limited scientific support exists for training incorporating rhythm and music as well as therapeutic riding and well-designed trials to determine the effectiveness of these treatment modalities are warranted. Methods/Design A single blinded three-armed randomized controlled trial is described with the aim to evaluate whether it is possible to improve the overall health status and functioning of individuals in the late phase of stroke (1-5 years after stroke) through a rhythm and music-based therapy program or therapeutic riding. About 120 individuals will be consecutively and randomly allocated to one of three groups: (T1) rhythm and music-based therapy program; (T2) therapeutic riding; or (T3) control group receiving the T1 training program a year later. Evaluation is conducted prior to and after the 12-week long intervention as well as three and six months later. The evaluation comprises a comprehensive functional and cognitive assessment (both qualitative and quantitative), and questionnaires. Based on the International classification of functioning, disability, and health (ICF), the outcome measures are classified into six comprehensive domains, with participation as the primary outcome measure assessed by the Stroke Impact Scale (SIS, version 2.0.). The secondary outcome measures are grouped within the following domains: body function, activity, environmental factors and personal factors. Life satisfaction and health related quality of life constitute an additional domain. Current status A total of 84 participants were randomised and have completed the intervention. Recruitment proceeds and follow-up is on-going, trial results are expected in early 2014. Discussion This study will ascertain whether any of the two intervention programs can improve overall health status and functioning in the late phase of stroke. A positive outcome would increase the scientific basis for the use of such interventions in the late phase after stroke. Trial registration Clinical Trials.gov Identifier: NCT01372059 PMID:23171380

Inducible nitric oxide synthase during the late phase of sepsis is associated with hypothermia and immune cell migration.

PubMed

Takatani, Yudai; Ono, Kenji; Suzuki, Hiromi; Inaba, Masato; Sawada, Makoto; Matsuda, Naoyuki

2018-02-14

Hypothermia is a significant sign of sepsis, which is associated with poor prognosis, but few mechanisms underlying the regulation of hypothermia are known. Inducible nitric oxide synthase (iNOS) is a key inflammatory mediator of sepsis. However, the therapeutic benefit of iNOS inhibition in sepsis is still controversial, and requires elucidation in an accurate model system. In this study, wild-type (WT) mice showed temperature drops in a biphasic manner at the early and late phase of sepsis, and all mice died within 48 h of sepsis. In contrast, iNOS-knockout (KO) mice never showed the second temperature drop and exhibited improved mortality. Plasma nitric oxide (NO) levels of WT mice increased in the late phase of sepsis and correlated to hypothermia. The results indicate that iNOS-derived NO during the late phase of sepsis caused vasodilation-induced hypothermia and a lethal hypodynamic state. The expression of the iNOS mRNA was high in the lung of WT mice with sepsis, which reflects the pathology of acute respiratory distress syndrome (ARDS). We obtained the results in a modified keyhole-type cecal ligation and puncture model of septic shock induced by minimally invasive surgery. In this accurate and reproducible model system, we transplanted the bone marrow cells of GFP transgenic mice into WT and iNOS-KO mice, and evaluated the role of increased pulmonary iNOS expression in cell migration during the late phase of sepsis. We also investigated the quantity and type of bone marrow-derived cells (BMDCs) in the lung. The number of BMDCs in the lung of iNOS-KO mice was less than that in the lung of WT mice. The major BMDCs populations were CD11b-positive, iNOS-negative cells in WT mice, and Gr-1-positive cells in iNOS-KO mice that expressed iNOS. These results suggest that sustained hypothermia may be a beneficial guide for future iNOS-targeted therapy of sepsis, and that iNOS modulated the migratory efficiency and cell type of BMDCs in septic ARDS.

The effects of a rhythm and music-based therapy program and therapeutic riding in late recovery phase following stroke: a study protocol for a three-armed randomized controlled trial.

PubMed

Bunketorp Käll, Lina; Lundgren-Nilsson, Åsa; Blomstrand, Christian; Pekna, Marcela; Pekny, Milos; Nilsson, Michael

2012-11-21

Stroke represents one of the most costly and long-term disabling conditions in adulthood worldwide and there is a need to determine the effectiveness of rehabilitation programs in the late phase after stroke. Limited scientific support exists for training incorporating rhythm and music as well as therapeutic riding and well-designed trials to determine the effectiveness of these treatment modalities are warranted. A single blinded three-armed randomized controlled trial is described with the aim to evaluate whether it is possible to improve the overall health status and functioning of individuals in the late phase of stroke (1-5 years after stroke) through a rhythm and music-based therapy program or therapeutic riding. About 120 individuals will be consecutively and randomly allocated to one of three groups: (T1) rhythm and music-based therapy program; (T2) therapeutic riding; or (T3) control group receiving the T1 training program a year later. Evaluation is conducted prior to and after the 12-week long intervention as well as three and six months later. The evaluation comprises a comprehensive functional and cognitive assessment (both qualitative and quantitative), and questionnaires. Based on the International classification of functioning, disability, and health (ICF), the outcome measures are classified into six comprehensive domains, with participation as the primary outcome measure assessed by the Stroke Impact Scale (SIS, version 2.0.). The secondary outcome measures are grouped within the following domains: body function, activity, environmental factors and personal factors. Life satisfaction and health related quality of life constitute an additional domain. A total of 84 participants were randomised and have completed the intervention. Recruitment proceeds and follow-up is on-going, trial results are expected in early 2014. This study will ascertain whether any of the two intervention programs can improve overall health status and functioning in the late phase of stroke. A positive outcome would increase the scientific basis for the use of such interventions in the late phase after stroke. Clinical Trials.gov Identifier: NCT01372059.

Photometric normalization of LROC WAC images

NASA Astrophysics Data System (ADS)

Sato, H.; Denevi, B.; Robinson, M. S.; Hapke, B. W.; McEwen, A. S.; LROC Science Team

2010-12-01

The Lunar Reconnaissance Orbiter Camera (LROC) Wide Angle Camera (WAC) acquires near global coverage on a monthly basis. The WAC is a push frame sensor with a 90° field of view (FOV) in BW mode and 60° FOV in 7-color mode (320 nm to 689 nm). WAC images are acquired during each orbit in 10° latitude segments with cross track coverage of ~50 km. Before mosaicking, WAC images are radiometrically calibrated to remove instrumental artifacts and to convert at sensor radiance to I/F. Images are also photometrically normalized to common viewing and illumination angles (30° phase), a challenge due to the wide angle nature of the WAC where large differences in phase angle are observed in a single image line (±30°). During a single month the equatorial incidence angle drifts about 28° and over the course of ~1 year the lighting completes a 360° cycle. The light scattering properties of the lunar surface depend on incidence(i), emission(e), and phase(p) angles as well as soil properties such as single-scattering albedo and roughness that vary with terrain type and state of maturity [1]. We first tested a Lommel-Seeliger Correction (LSC) [cos(i)/(cos(i) + cos(e))] [2] with a phase function defined by an exponential decay plus 4th order polynomial term [3] which did not provide an adequate solution. Next we employed a LSC with an exponential 2nd order decay phase correction that was an improvement, but still exhibited unacceptable frame-to-frame residuals. In both cases we fitted the LSC I/F vs. phase angle to derive the phase corrections. To date, the best results are with a lunar-lambert function [4] with exponential 2nd order decay phase correction (LLEXP2) [(A1exp(B1p)+A2exp(B2p)+A3) * cos(i)/(cos(e) + cos(i)) + B3cos(i)]. We derived the parameters for the LLEXP2 from repeat imaging of a small region and then corrected that region with excellent results. When this correction was applied to the whole Moon the results were less than optimal - no surprise given the variability of the regolith from region to region. As the fitting area increases, the accuracy of curve fitting decreases due to the larger variety of albedo, topography, and composition. Thus we have adopted an albedo-dependent photometric normalization routine. Phase curves are derived for discreet bins of preliminary normalized reflectance calculated from Clementine global mosaic in a fitting area that is composed of predominantly mare in Oceanus Procellarum. The global WAC mosaic was then corrected pixel-by-pixel according to its preliminary reflectance map with satisfactory results. We observed that the phase curves per normalized-reflectance bins become steeper as the reflectance value increases. Further filtering by using FeO, TiO2, or optical maturity [5] for parameter calculations may help elucidate the effects of surface composition and maturity on photometric properties of the surface. [1] Hapke, B.W. (1993) Theory of Reflectance and Emittance Spectroscopy, Cambridge Univ. Press. [2] Schoenberg (1925) Ada. Soc. Febb., vol. 50. [3] Hillier et al. (1999) Icarus 141, 205-225. [4] McEwen (1991) Icarus 92, 298-311. [5] Lucey et al. (2000) JGR, v105, no E8, p20377-20386.

Fast radiative transfer models for retrieval of cloud properties in the back-scattering region: application to DSCOVR-EPIC sensor

NASA Astrophysics Data System (ADS)

Molina Garcia, Victor; Sasi, Sruthy; Efremenko, Dmitry; Doicu, Adrian; Loyola, Diego

2017-04-01

In this work, the requirements for the retrieval of cloud properties in the back-scattering region are described, and their application to the measurements taken by the Earth Polychromatic Imaging Camera (EPIC) on board the Deep Space Climate Observatory (DSCOVR) is shown. Various radiative transfer models and their linearizations are implemented, and their advantages and issues are analyzed. As radiative transfer calculations in the back-scattering region are computationally time-consuming, several acceleration techniques are also studied. The radiative transfer models analyzed include the exact Discrete Ordinate method with Matrix Exponential (DOME), the Matrix Operator method with Matrix Exponential (MOME), and the approximate asymptotic and equivalent Lambertian cloud models. To reduce the computational cost of the line-by-line (LBL) calculations, the k-distribution method, the Principal Component Analysis (PCA) and a combination of the k-distribution method plus PCA are used. The linearized radiative transfer models for retrieval of cloud properties include the Linearized Discrete Ordinate method with Matrix Exponential (LDOME), the Linearized Matrix Operator method with Matrix Exponential (LMOME) and the Forward-Adjoint Discrete Ordinate method with Matrix Exponential (FADOME). These models were applied to the EPIC oxygen-A band absorption channel at 764 nm. It is shown that the approximate asymptotic and equivalent Lambertian cloud models give inaccurate results, so an offline processor for the retrieval of cloud properties in the back-scattering region requires the use of exact models such as DOME and MOME, which behave similarly. The combination of the k-distribution method plus PCA presents similar accuracy to the LBL calculations, but it is up to 360 times faster, and the relative errors for the computed radiances are less than 1.5% compared to the results when the exact phase function is used. Finally, the linearized models studied show similar behavior, with relative errors less than 1% for the radiance derivatives, but FADOME is 2 times faster than LDOME and 2.5 times faster than LMOME.

Synthesis of Pt 3Y and Other Early–Late Intermetallic Nanoparticles by Way of a Molten Reducing Agent

DOE PAGES

Kanady, Jacob S.; Leidinger, Peter; Haas, Andreas; ...

2017-03-29

Early–late intermetallic phases have garnered increased attention recently for their catalytic properties. To achieve the high surface areas needed for industrially relevant applications, these phases must be synthesized as nanoparticles in a scalable fashion. Herein, Pt 3Y—targeted as a prototypical example of an early–late intermetallic—has been synthesized as nanoparticles approximately 5–20 nm in diameter via a solution process and characterized by XRD, TEM, EDS, and XPS. The key development is the use of a molten borohydride (MEt 3BH, M = Na, K) as both the reducing agent and reaction medium. Readily available halide precursors of the two metals are used.more » Accordingly, no organic ligands are necessary, as the resulting halide salt byproduct prevents sintering, which further permits dispersion of the nanoscale intermetallic onto a support. The versatility of this approach was validated by the synthesis of other intermetallic phases such as Pt 3Sc, Pt 3Lu, Pt 2Na, and Au 2Y.« less

Synthesis of Pt 3Y and Other Early–Late Intermetallic Nanoparticles by Way of a Molten Reducing Agent

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

Kanady, Jacob S.; Leidinger, Peter; Haas, Andreas

Early–late intermetallic phases have garnered increased attention recently for their catalytic properties. To achieve the high surface areas needed for industrially relevant applications, these phases must be synthesized as nanoparticles in a scalable fashion. Herein, Pt 3Y—targeted as a prototypical example of an early–late intermetallic—has been synthesized as nanoparticles approximately 5–20 nm in diameter via a solution process and characterized by XRD, TEM, EDS, and XPS. The key development is the use of a molten borohydride (MEt 3BH, M = Na, K) as both the reducing agent and reaction medium. Readily available halide precursors of the two metals are used.more » Accordingly, no organic ligands are necessary, as the resulting halide salt byproduct prevents sintering, which further permits dispersion of the nanoscale intermetallic onto a support. The versatility of this approach was validated by the synthesis of other intermetallic phases such as Pt 3Sc, Pt 3Lu, Pt 2Na, and Au 2Y.« less

Endocrine changes in male stumptailed macaques (Macaca arctoides) as a response to odor stimulation with vaginal secretions.

PubMed

Cerda-Molina, Ana Lilia; Hernández-López, Leonor; Chavira, Roberto; Cárdenas, Mario; Paez-Ponce, Denisse; Cervantes-De la Luz, Harry; Mondragón-Ceballos, Ricardo

2006-01-01

In mammalian species, social chemosignals are important in modulating endocrine reproductive functions. In nonhuman primates, previous studies have described a high frequency of mounting behavior by females in the follicular and periovulatory phases of the menstrual cycle. Stumptailed macaque females do not signal receptivity by means of sexual swellings, as do others macaques, therefore providing a good model in which to study chemical signaling of reproductive status. We exposed anesthetized stumptailed males to vaginal secretions of either late follicular or menses phase or to saline solution to determine the endocrine changes promoting male sexual behavior. In males exposed to follicular secretions, plasma testosterone concentrations were sustained up to 120 min after exposure. Such an effect was not observed in animals exposed to menses or saline odor sources. A luteinizing hormone surge, occurring 30 minutes after exposure to late follicular phase secretion swabs, preceded this sustained testosterone effect. The fact that late follicular scents induce sustained testosterone concentrations provides support to the idea that stumptailed males draw information concerning female reproductive status from the female's vaginal odor.

Relative role of pre-monsoon conditions and intraseasonal oscillations in determining early-vs-late indian monsoon intensity in a GCM

NASA Astrophysics Data System (ADS)

Ghosh, Rohit; Chakraborty, Arindam; Nanjundiah, Ravi S.

2018-01-01

The aim of this paper is to identify relative roles of different land-atmospheric conditions, apart from sea surface temperature (SST), in determining early vs. late summer monsoon intensity over India in a high resolution general circulation model (GCM). We find that in its early phase (June-July; JJ), pre-monsoon land-atmospheric processes play major role to modulate the precipitation over Indian region. These effects of pre-monsoon conditions decrease substantially during its later phase (August-September; AS) for which the interannual variation is mainly governed by the low frequency northward propagating intraseasonal oscillations. This intraseasonal variability which is related to mean vertical wind shear has a significant role during the early phase of monsoon as well. Further, using multiple linear regression, we show that interannual variation of early and late monsoon rainfall over India is best explained when all these land-atmospheric parameters are taken together. Our study delineates the relative role of different processes affecting early versus later summer monsoon rainfall over India that can be used for determining its subseasonal predictability.

Purification and properties of two terminal oxidase complexes of Escherichia coli aerobic respiratory chain.

PubMed

Kita, K; Konishi, K; Anraku, Y

1986-01-01

Two terminal oxidase complexes, cytochrome b-562-o complex and cytochrome b-558-d complex, are isolated in highly purified forms which show ubiquinol oxidase activities. From the result of steady-state kinetics of cytochromes in the membrane and E'm values of purified cytochromes, we propose a branched arrangement of the late exponential phase of aerobic growth, as shown in Fig. 10. Cytochrome b-556 is reduced by several dehydrogenases and the gene for this cytochrome (cybA) is located in the sdh gene cluster. Recently, we found another low-potential b-type cytochrome, cytochrome b-561 (Em' = 20 mV), which is also reduced by dehydrogenases. The position of this new cytochrome in the aerobic respiratory chain is under investigation. Two terminal oxidase complexes branch at the site of ubiquinone-8, and the Km value for oxygen of the purified cytochrome b-558-d complex is about 8-fold lower than that of the purified cytochrome b-562-o complex when ubiquinol-1 is used as substrate. This result is consistent with the idea that the cytochrome b-558-d complex is synthesized as an alternative oxidase for more efficient utilization of oxygen at low oxygen concentration. Thus, E. coli cells can maintain efficient oxidative energy conservation over a wide range of oxygen pressures by simply changing the contents of the two terminal oxidases, each of which functions as a coupling site.

Enhanced eicosapentaenoic acid production by a new deep-sea marine bacterium Shewanella electrodiphila MAR441T.

PubMed

Zhang, Jinwei; Burgess, J Grant

2017-01-01

Omega-3 fatty acids are products of secondary metabolism, essential for growth and important for human health. Although there are numerous reports of bacterial production of omega-3 fatty acids, less information is available on the biotechnological production of these compounds from bacteria. The production of eicosapentaenoic acid (EPA, 20:5ω3) by a new species of marine bacteria Shewanella electrodiphila MAR441T was investigated under different fermentation conditions. This strain produced a high percentage (up to 26%) of total fatty acids and high yields (mg / g of biomass) of EPA at or below the optimal growth temperature. At higher growth temperatures these values decreased greatly. The amount of EPA produced was affected by the carbon source, which also influenced fatty acid composition. This strain required Na+ for growth and EPA synthesis and cells harvested at late exponential or early stationary phase had a higher EPA content. Both the highest amounts (20 mg g-1) and highest percent EPA content (18%) occurred with growth on L-proline and (NH4)2SO4. The addition of cerulenin further enhanced EPA production to 30 mg g-1. Chemical mutagenesis using NTG allowed the isolation of mutants with improved levels of EPA content (from 9.7 to 15.8 mg g-1) when grown at 15°C. Thus, the yields of EPA could be substantially enhanced without the need for recombinant DNA technology, often a commercial requirement for food supplement manufacture.

Disk irradiation and light curves of x ray novae

NASA Technical Reports Server (NTRS)

Kim, S.-W.; Wheeler, J. C.; Mineshige, S.

1994-01-01

We study the disk instability and the effect of irradiation on outbursts in the black hole X-ray nova system. In both the optical and soft X-rays, the light curves of several X-ray novae, A0620-00, GH 2000+25, Nova Muscae 1991 (GS 1124-68), and GRO J0422+32, show a main peak, a phase of exponential decline, a secondary maximum or reflare, and a final bump in the late decay followed by a rapid decline. Basic disk thermal limit cycle instabilities can account for the rapid rise and overall decline, but not the reflare and final bump. The rise time of the reflare, about 10 days, is too short to represent a viscous time, so this event is unlikely to be due to increased mass flow from the companion star. We explore the possibility that irradiation by X-rays produced in the inner disk can produce these secondary effects by enhancing the mass flow rate within the disk. Two plausible mechanisms of irradiation of the disk are considered: direct irradiation from the inner hot disk and reflected radiation from a corona or other structure above the disk. Both of these processes will be time dependent in the context of the disk instability model and result in more complex time-dependent behavior of the disk structure. We test both disk instability and mass transfer burst models for the secondary flares in the presence of irradiation.

Application of environmental tracers to mixing, evolution, and nitrate contamination of ground water in Jeju Island, Korea

USGS Publications Warehouse

Koh, D.-C.; Plummer, Niel; Kip, Solomon D.; Busenberg, E.; Kim, Y.-J.; Chang, H.-W.

2006-01-01

Tritium/helium-3 (3H/3He) and chlorofluorocarbons (CFCs) were investigated as environmental tracers in ground water from Jeju Island (Republic of Korea), a basaltic volcanic island. Ground-water mixing was evaluated by comparing 3H and CFC-12 concentrations with lumped-parameter dispersion models, which distinguished old water recharged before the 1950s with negligible 3H and CFC-12 from younger water. Low 3H levels in a considerable number of samples cannot be explained by the mixing models, and were interpreted as binary mixing of old and younger water; a process also identified in alkalinity and pH of ground water. The ground-water CFC-12 age is much older in water from wells completed in confined zones of the hydro-volcanic Seogwipo Formation in coastal areas than in water from the basaltic aquifer. Major cation concentrations are much higher in young water with high nitrate than those in uncontaminated old water. Chemical evolution of ground water resulting from silicate weathering in basaltic rocks reaches the zeolite-smectite phase boundary. The calcite saturation state of ground water increases with the CFC-12 apparent (piston flow) age. In agricultural areas, the temporal trend of nitrate concentration in ground water is consistent with the known history of chemical fertilizer use on the island, but increase of nitrate concentration in ground water is more abrupt after the late 1970s compared with the exponential growth of nitrogen inputs. ?? 2005 Elsevier B.V. All rights reserved.

Effect of gamma 60Co irradiation on the lipid content and fatty acid composition of Nannochloropsis sp. microalgae

NASA Astrophysics Data System (ADS)

Ermavitalini, Dini; Sari, Ika Puspita; Prasetyo, Endry Nugroho; Abdulgani, Nurlita; Saputro, Triono Bagus

2017-06-01

Nannochloropsissp. has been identified as a promising feed stock for biodiesel production in recent years. Nannochloropsis sp. have high lipid content between 31-68 % of dry biomass weight. Mutagenesis induced by Gamma 60Co irradiation can be utilized to alter Nannochloropsis sp. characteristic to get microalgae mutant strain that can produce a higher lipid content than the wild strain. The aim of this research was to know the effect of gamma 60Co irradiation to the biomass, lipid content and fatty acid compotition of Nannochloropsis sp. microalgae. In this research, irradiation was done in different doses there were 0, 2, 4, 6 and 10 Gray (Gy). Measuring microalgae biomass and lipid content were done in late exponential phase at the end of each treatment. Research design used is random complete with 95 % confident level for quantitative analysis based on biomass and lipid content. Fatty acid compotition was analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that gamma irradiated gave an effect on lipid content and fatty acid profile of Nannochloropsis sp. Tukey test showed total lipid content of control micoalgae (0 Gy) was significat different with 10 Gy irradiated microalgae, but no significant different with 2,4 and 6 Gy irradiated microalgae. The highest lipid content were found in 10 Gy irradiated microalgae equal to 62.65 %. Fatty acid profile of 10 Gy irradiated Nannochloropsis sp. had 9 fatty acids while control Nannochloropsis sp. had 6 fatty acids.

Enhanced eicosapentaenoic acid production by a new deep-sea marine bacterium Shewanella electrodiphila MAR441T

PubMed Central

Burgess, J. Grant

2017-01-01

Omega-3 fatty acids are products of secondary metabolism, essential for growth and important for human health. Although there are numerous reports of bacterial production of omega-3 fatty acids, less information is available on the biotechnological production of these compounds from bacteria. The production of eicosapentaenoic acid (EPA, 20:5ω3) by a new species of marine bacteria Shewanella electrodiphila MAR441T was investigated under different fermentation conditions. This strain produced a high percentage (up to 26%) of total fatty acids and high yields (mg / g of biomass) of EPA at or below the optimal growth temperature. At higher growth temperatures these values decreased greatly. The amount of EPA produced was affected by the carbon source, which also influenced fatty acid composition. This strain required Na+ for growth and EPA synthesis and cells harvested at late exponential or early stationary phase had a higher EPA content. Both the highest amounts (20 mg g-1) and highest percent EPA content (18%) occurred with growth on L-proline and (NH4)2SO4. The addition of cerulenin further enhanced EPA production to 30 mg g-1. Chemical mutagenesis using NTG allowed the isolation of mutants with improved levels of EPA content (from 9.7 to 15.8 mg g-1) when grown at 15°C. Thus, the yields of EPA could be substantially enhanced without the need for recombinant DNA technology, often a commercial requirement for food supplement manufacture. PMID:29176835

A scaling law of radial gas distribution in disk galaxies

NASA Technical Reports Server (NTRS)

Wang, Zhong

1990-01-01

Based on the idea that local conditions within a galactic disk largely determine the region's evolution time scale, researchers built a theoretical model to take into account molecular cloud and star formations in the disk evolution process. Despite some variations that may be caused by spiral arms and central bulge masses, they found that many late-type galaxies show consistency with the model in their radial atomic and molecular gas profiles. In particular, researchers propose that a scaling law be used to generalize the gas distribution characteristics. This scaling law may be useful in helping to understand the observed gas contents in many galaxies. Their model assumes an exponential mass distribution with disk radius. Most of the mass are in atomic gas state at the beginning of the evolution. Molecular clouds form through a modified Schmidt Law which takes into account gravitational instabilities in a possible three-phase structure of diffuse interstellar medium (McKee and Ostriker, 1977; Balbus and Cowie, 1985); whereas star formation proceeds presumably unaffected by the environmental conditions outside of molecular clouds (Young, 1987). In such a model both atomic and molecular gas profiles in a typical galactic disk (as a result of the evolution) can be fitted simultaneously by adjusting the efficiency constants. Galaxies of different sizes and masses, on the other hand, can be compared with the model by simply scaling their characteristic length scales and shifting their radial ranges to match the assumed disk total mass profile sigma tot(r).

Phosphorus-zinc interactive effects on growth by Selenastrum capricornutum (chlorophyta)

USGS Publications Warehouse

Kuwabara, J.S.

1985-01-01

Culturing experiments in chemically defined growth media were conducted to observe possible Zn and P interactions on Selenastrum capricornutum Printz growth indexes. Elevated Zn concentrations (7.5 ?? 10-8 and 1.5 ?? 10-7 M [Zn2+]) were highly detrimental to algal growth, affecting lag, exponential, and stationary growth phases. P behaved as a yield-limiting nutrient with maximum cell densities increasing linearly with total P. This yield limitation was intensified at elevated Zn concentrations. Although calculated cellular phosphorus concentrations increased markedly with Zn ion activity, elevated Zn concentrations had no apparent effect on rates of phosphorus uptake estimated for Selenastrum during exponential growth. Results indicated that P-Zn interactions were significant in describing Selenastrum cell yield results and are consistent with previous Zn studies on chlorophytes. These P-Zn interactions and the observed inhibitory growth effects of submicromolar Zn concentrations suggest that in nature an apparent P yield-limiting condition may result from elevated Zn concentrations.

Effect of the state of internal boundaries on granite fracture nature under quasi-static compression

NASA Astrophysics Data System (ADS)

Damaskinskaya, E. E.; Panteleev, I. A.; Kadomtsev, A. G.; Naimark, O. B.

2017-05-01

Based on an analysis of the spatial distribution of hypocenters of acoustic emission signal sources and an analysis of the energy distributions of acoustic emission signals, the effect of the liquid phase and a weak electric field on the spatiotemporal nature of granite sample fracture is studied. Experiments on uniaxial compression of granite samples of natural moisture showed that the damage accumulation process is twostage: disperse accumulation of damages is followed by localized accumulation of damages in the formed macrofracture nucleus region. In energy distributions of acoustic emission signals, this transition is accompanied by a change in the distribution shape from exponential to power-law. Granite water saturation qualitatively changes the damage accumulation nature: the process is delocalized until macrofracture with the exponential energy distribution of acoustic emission signals. An exposure to a weak electric field results in a selective change in the damage accumulation nature in the sample volume.

Mathematical modeling of ethanol production in solid-state fermentation based on solid medium' dry weight variation.

PubMed

Mazaheri, Davood; Shojaosadati, Seyed Abbas; Zamir, Seyed Morteza; Mousavi, Seyyed Mohammad

2018-04-21

In this work, mathematical modeling of ethanol production in solid-state fermentation (SSF) has been done based on the variation in the dry weight of solid medium. This method was previously used for mathematical modeling of enzyme production; however, the model should be modified to predict the production of a volatile compound like ethanol. The experimental results of bioethanol production from the mixture of carob pods and wheat bran by Zymomonas mobilis in SSF were used for the model validation. Exponential and logistic kinetic models were used for modeling the growth of microorganism. In both cases, the model predictions matched well with the experimental results during the exponential growth phase, indicating the good ability of solid medium weight variation method for modeling a volatile product formation in solid-state fermentation. In addition, using logistic model, better predictions were obtained.

AMPK is activated early in cerebellar granule cells undergoing apoptosis and influences VADC1 phosphorylation status and activity.

PubMed

Bobba, A; Casalino, E; Amadoro, G; Petragallo, V A; Atlante, A

2017-09-01

The neurodegeneration of cerebellar granule cells, after low potassium induced apoptosis, is known to be temporally divided into an early and a late phase. Voltage-dependent anion channel-1 (VDAC1) protein, changing from the closed inactive state to the active open state, is central to the switch between the early and late phase. It is also known that: (i) VDAC1 can undergo phosphorylation events and (ii) AMP-activated protein kinase (AMPK), the sensor of cellular stress, may have a role in neuronal homeostasis. In the view of this, the involvement of AMPK activation and its correlation with VDAC1 status and activity has been investigated in the course of cerebellar granule cells apoptosis. The results reported in this study show that an increased level of the phosphorylated, active, isoform of AMPK occurs in the early phase, peaks at 3 h and guarantees an increase in the phosphorylation status of VDCA1, resulting in a reduced activity of this latter. However this situation is transient in nature, since, in the late phase, AMPK activation decreases as well as the level of phosphorylated VDAC1. In a less phosphorylated status, VDAC1 fully recovers its gating activity and drives cells along the death route.

A colloquium on the influence of versatile class of saturable nonlinear responses in the instability induced supercontinuum generation

NASA Astrophysics Data System (ADS)

Nithyanandan, K.; Vasantha Jayakantha Raja, R.; Porsezian, K.; Uthayakumar, T.

2013-08-01

We investigate the modulational instability induced supercontinuum generation (MI-SCG) under versatile saturable nonlinear (SNL) responses. We identify and discuss the salient features of saturable nonlinear responses of various functional forms such as exponential, conventional and coupled type on modulational instability (MI) and the subsequent supercontinuum (SC) process. Firstly, we analyze the impact of SNL on the MI spectrum and found both analytically and numerically that MI gain and bandwidth is maximum for exponential nonlinearity in comparison to other types of SNL's. We also reported the unique behavior of the SNL system in the MI dynamics. Following the MI analysis, the proceeding section deals with the supercontinuum generation (SCG) process by virtue of MI. We examine exclusively the impact of each form of SNL on the SC spectrum and predicted numerically that exponential case attains the phase matching earlier and thus enable to achieve broad spectrum at a relatively shorter distance of propagation than the other cases of SNL's. Thus a direct evidence of SCG from MI is emphasized and the impact of SNL in MI-SCG is highlighted. To analyze the quality of the output continuum spectrum, we performed the coherence analysis for MI-SCG in the presence of SNL.

From Experiment to Theory: What Can We Learn from Growth Curves?

PubMed

Kareva, Irina; Karev, Georgy

2018-01-01

Finding an appropriate functional form to describe population growth based on key properties of a described system allows making justified predictions about future population development. This information can be of vital importance in all areas of research, ranging from cell growth to global demography. Here, we use this connection between theory and observation to pose the following question: what can we infer about intrinsic properties of a population (i.e., degree of heterogeneity, or dependence on external resources) based on which growth function best fits its growth dynamics? We investigate several nonstandard classes of multi-phase growth curves that capture different stages of population growth; these models include hyperbolic-exponential, exponential-linear, exponential-linear-saturation growth patterns. The constructed models account explicitly for the process of natural selection within inhomogeneous populations. Based on the underlying hypotheses for each of the models, we identify whether the population that it best fits by a particular curve is more likely to be homogeneous or heterogeneous, grow in a density-dependent or frequency-dependent manner, and whether it depends on external resources during any or all stages of its development. We apply these predictions to cancer cell growth and demographic data obtained from the literature. Our theory, if confirmed, can provide an additional biomarker and a predictive tool to complement experimental research.

Two Components of Voltage-Dependent Inactivation in Cav1.2 Channels Revealed by Its Gating Currents

PubMed Central

Ferreira, Gonzalo; Ríos, Eduardo; Reyes, Nicolás

2003-01-01

Voltage-dependent inactivation (VDI) was studied through its effects on the voltage sensor in Cav1.2 channels expressed in tsA 201 cells. Two kinetically distinct phases of VDI in onset and recovery suggest the presence of dual VDI processes. Upon increasing duration of conditioning depolarizations, the half-distribution potential (V1/2) of intramembranous mobile charge was negatively shifted as a sum of two exponential terms, with time constants 0.5 s and 4 s, and relative amplitudes near 50% each. This kinetics behavior was consistent with that of increment of maximal charge related to inactivation (Qn). Recovery from inactivation was also accompanied by a reduction of Qn that varied with recovery time as a sum of two exponentials. The amplitudes of corresponding exponential terms were strongly correlated in onset and recovery, indicating that channels recover rapidly from fast VDI and slowly from slow VDI. Similar to charge “immobilization,” the charge moved in the repolarization (OFF) transient became slower during onset of fast VDI. Slow VDI had, instead, hallmarks of interconversion of charge. Confirming the mechanistic duality, fast VDI virtually disappeared when Li+ carried the current. A nine-state model with parallel fast and slow inactivation pathways from the open state reproduces most of the observations. PMID:12770874