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Sample records for methanogenesis primarily drive

  1. Control of rumen methanogenesis.

    PubMed

    Van Nevel, C J; Demeyer, D I

    1996-09-01

    During the last decades, considerable research on methane production in the rumen and its inhibition has been carried out. Initially, as methane production represents a significant loss of gross energy in the feed (2-15%), the ultimate goal of such intervention in rumen fermentation was an increase in feed efficiency. A second reason favouring research on methane inhibition is its role in the global warming phenomenon and in the destruction of the ozone layer. In this review, the authors describe briefly several interventions for reducing methane emission by ruminants. The objective can be reached by intervention at the dietary level by ration manipulation (composition, feeding level) or by the use of additives or supplements. Examples of additives are polyhalogenated compounds, ionophores and other antibiotics. Supplementation of the ration with lipids also lowered methanogenesis. More biotechnological interventions, e.g., defaunation, probiotics and introduction of reductive acetogenesis in the rumen, are also mentioned. It can be concluded that drastic inhibition of methane production is not unequivocally successful as a result of several factors, such as: instantaneous inhibition often followed by restoration of methanogenesis due to adaptation of the microbes or degradation of the additive, toxicity for the host animal, negative effects on overall digestion and productive performance. Therefore, methanogenesis and its inhibition cannot be considered as a separate part of rumen fermentation and its consequences on the animal should be taken into account.

  2. The unique biochemistry of methanogenesis.

    PubMed

    Deppenmeier, Uwe

    2002-01-01

    Methanogenic archaea have an unusual type of metabolism because they use H2 + CO2, formate, methylated C1 compounds, or acetate as energy and carbon sources for growth. The methanogens produce methane as the major end product of their metabolism in a unique energy-generating process. The organisms received much attention because they catalyze the terminal step in the anaerobic breakdown of organic matter under sulfate-limiting conditions and are essential for both the recycling of carbon compounds and the maintenance of the global carbon flux on Earth. Furthermore, methane is an important greenhouse gas that directly contributes to climate changes and global warming. Hence, the understanding of the biochemical processes leading to methane formation are of major interest. This review focuses on the metabolic pathways of methanogenesis that are rather unique and involve a number of unusual enzymes and coenzymes. It will be shown how the previously mentioned substrates are converted to CH4 via the CO2-reducing, methylotrophic, or aceticlastic pathway. All catabolic processes finally lead to the formation of a mixed disulfide from coenzyme M and coenzyme B that functions as an electron acceptor of certain anaerobic respiratory chains. Molecular hydrogen, reduced coenzyme F420, or reduced ferredoxin are used as electron donors. The redox reactions as catalyzed by the membrane-bound electron transport chains are coupled to proton translocation across the cytoplasmic membrane. The resulting electrochemical proton gradient is the driving force for ATP synthesis as catalyzed by an A1A0-type ATP synthase. Other energy-transducing enzymes involved in methanogenesis are the membrane-integral methyltransferase and the formylmethanofuran dehydrogenase complex. The former enzyme is a unique, reversible sodium ion pump that couples methyl-group transfer with the transport of Na+ across the membrane. The formylmethanofuran dehydrogenase is a reversible ion pump that catalyzes

  3. Does Methanogenesis Require Oxygen?

    NASA Astrophysics Data System (ADS)

    Shoemaker, J. K.; Schrag, D. P.

    2011-12-01

    Despite the importance of methane biogeochemistry to climate studies, a mechanistic understanding of what controls methane production and emissions from natural sources is still lacking. Using an isotope mass balance of the CO2 dissolved in the pore waters at Sallie's Fen, a New Hampshire wetland, we find that the carbon isotopes from the pore waters do not account for the methane emissions observed from this site. In order to try and close the isotope mass balance, we sampled gases from the unsaturated peat at the same location multiple times throughout a summer season. We found a subset of the gas samples to contain high concentrations of CO2 with very enriched carbon isotopic signatures. Such a signal can only be explained by a signficiant contribution of methanogenic CO2 to these samples, which would not occur if this methane was produced deep within the pore waters. The transport of CO2 in wetland pore waters, unlike methane, is dominated by diffusion. For this reason, the CO2 produced as a biproduct of subsurface methanogenesis emerges slowly from the pore waters and the isotopic signal would be masked by respiration, which is the dominant source of CO2 flux. Instead, these samples indicate a potentially large, but unquantified, source of methane from either the surface pore water or the unsaturated peat. Although archael methane producers are obligately anaerobic, they rely on a cascade of both anaerobic and aerobic processes for providing available carbon substrates. We suggest that the primary factor limiting both fermentation and methane production in terrestrial soils is a lack of substrate supply from oxic processes. More specifically, methanogenesis in terrestrial soils may be constrained by the same step that limits bulk organic matter degradation in saturated soils - the activity of oxic exoenzymes that break down complex organic material such that it is available to microbial degraders. This results in the majority of methane production occurring at

  4. Microbial ecosystem and methanogenesis in ruminants.

    PubMed

    Morgavi, D P; Forano, E; Martin, C; Newbold, C J

    2010-07-01

    Ruminant production is under increased public scrutiny in terms of the importance of cattle and other ruminants as major producers of the greenhouse gas methane. Methanogenesis is performed by methanogenic archaea, a specialised group of microbes present in several anaerobic environments including the rumen. In the rumen, methanogens utilise predominantly H2 and CO2 as substrates to produce methane, filling an important functional niche in the ecosystem. However, in addition to methanogens, other microbes also have an influence on methane production either because they are involved in hydrogen (H2) metabolism or because they affect the numbers of methanogens or other members of the microbiota. This study explores the relationship between some of these microbes and methanogenesis and highlights some functional groups that could play a role in decreasing methane emissions. Dihydrogen ('H2' from this point on) is the key element that drives methane production in the rumen. Among H2 producers, protozoa have a prominent position, which is strengthened by their close physical association with methanogens, which favours H2 transfer from one to the other. A strong positive interaction was found between protozoal numbers and methane emissions, and because this group is possibly not essential for rumen function, protozoa might be a target for methane mitigation. An important function that is associated with production of H2 is the degradation of fibrous plant material. However, not all members of the rumen fibrolytic community produce H2. Increasing the proportion of non-H2 producing fibrolytic microorganisms might decrease methane production without affecting forage degradability. Alternative pathways that use electron acceptors other than CO2 to oxidise H2 also exist in the rumen. Bacteria with this type of metabolism normally occupy a distinct ecological niche and are not dominant members of the microbiota; however, their numbers can increase if the right potential

  5. Sulfate reduction and methanogenesis in marine sediments

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  6. Evidence for Methanogenesis in ANME Archaea

    NASA Astrophysics Data System (ADS)

    Lloyd, K. G.; Kevorkian, R.

    2014-12-01

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

  7. Abiogenic methanogenesis in crystalline rocks

    SciTech Connect

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

    1993-12-01

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

  8. Laboratory support for a methanogenesis driven

    NASA Astrophysics Data System (ADS)

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

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

  9. A New Era of Methanogenesis Research.

    PubMed

    Lever, Mark Alexander

    2016-02-01

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

  10. Inhibition of methanogenesis by human bile.

    PubMed Central

    Florin, T H; Woods, H J

    1995-01-01

    The factors that regulate methanogenesis in humans have not been established. The presence of bile acid, which is lost into the colon from the small intestine, may be an important regulatory factor of methanogenesis. To examine this possibility, the effect of human bile on methane production by faecal cultures, and the in vivo effect of biliary diversion on breath methane excretion in a methanogenic choledochostomy patient, were investigated. Faecal suspensions (0.1%) from five methanogenic humans were incubated anaerobically with bile (0.3-30%) from three choledochostomy patients, and headspace methane measured by gas chromatography. All biles inhibited headspace methane. Inhibition of methanogenesis was dose dependent, plateaued at 10-30% bile concentration, and was abolished by 0.6% cholestyramine. The maximum inhibition by bile, median (range), was 38 (0.9-56)% of control methane values. Reversal of the bile fistula in the fourth choledochostomy patient converted that subject from methanogenic to 'non-methanogenic' status, It is concluded that inhibition of methanogens in the caecum by bile acid could significantly reduce the number of methanogens in the colon. This and the effect of transit time could explain much of the known epidemiology of 'non-methanogenesis', which has been related to obesity, (comparatively) fast colonic transit in healthy persons, and to small intestinal Crohn's disease. PMID:7590441

  11. Microbiology of methanogenesis in thermal, volcanic environments.

    PubMed

    Zeikus, J G; Ben-Bassat, A; Hegge, P W

    1980-07-01

    Microbial methanogenesis was examined in thermal waters, muds, and decomposing algal-bacterial mats associated with volcanic activity in Yellowstone National Park. Radioactive tracer studies with [(14)C]glucose, acetate, or carbonate and enrichment culture techniques demonstrated that methanogenesis occurred at temperatures near 70 degrees C but below 80 degrees C and correlated with hydrogen production from either geothermal processes or microbial fermentation. Three Methanobacterium thermoautotrophicum strains (YT1, YTA, and YTC) isolated from diverse volcanic habitats differed from the neotype sewage strain DeltaH in deoxyribonucleic acid guanosine-plus-cytosine content and immunological properties. Microbial methanogenesis was characterized in more detail at a 65 degrees C site in the Octopus Spring algal-bacterial mat ecosystem. Here methanogenesis was active, was associated with anaerobic microbial decomposition of biomass, occurred concomitantly with detectable microbial hydrogen formation, and displayed a temperature activity optimum near 65 degrees C. Enumeration studies estimated more than 10(9) chemoorganotrophic hydrolytic bacteria and 10(6) chemolithotrophic methanogenic bacteria per g (dry weight) of algal-bacterial mat. Enumeration, enrichment, and isolation studies revealed that the microbial population was predominantly rod shaped and asporogenous. A prevalent chemoorganotrophic organism in the mat that was isolated from an end dilution tube was a taxonomically undescribed gram-negative obligate anaerobe (strain HTB2), whereas a prevalent chemolithotrophic methanogen isolated from an end dilution tube was identified as M. thermoautotrophicum (strain YTB). Taxonomically recognizable obligate anaerobes that were isolated from glucose and xylose enrichment cultures included Thermoanaerobium brockii strain HTB and Clostridium thermohydrosulfuricum strain 39E. The nutritional properties, growth temperature optima, growth rates, and fermentation products

  12. Methanogenesis: surprising molecules, microorganisms and ecosystems.

    PubMed

    Vogels, G D; van der Drift, C; Stumm, C K; Keltjens, J T; Zwart, K B

    1984-01-01

    Methanogenesis involves a novel set of coenzymes as one-carbon and electron carriers. Consequently, metabolic processes of methanogens deviate from those present in non-methanogenic bacteria. Methanogenic bacteria can be classified on the basis of substrate utilization. Group I (24 species) grows at the expense of hydrogen plus CO2 and/or formate and group II (7 species) uses methanol and/or acetate. Hydrogen-consuming methanogens are found as epi- or endosymbionts of anaerobic ciliates.

  13. C-isotopic fractionation during methylotrophic methanogenesis

    SciTech Connect

    Summons, R.E.; Nichols, P.D.; Franzmann, P.D.

    1996-12-31

    Methanogenesis from non-competitive substrates such as trimethylamine (TMA) may be quantitatively important in global methane budgets. This is because choline, glycine betaine and related compounds, precursors of TMA, are produced abundantly and ubiquitously by microbes, particularly those from marine and saline lacustrine environments. These substrates may source methane supersaturating oceanic seawater, possibly formed in anaerobic microhabitats (e.g. zooplankton guts and within particulates) and indicated by carbon isotopic analysis of abundant methanogen-derived hydrocarbons (e.g. 2, 6, 10, 15, 19-pentamethyleicosane, PME) found in recent and ancient marine sediments. In order to elaborate on these observations using cultured organisms we measured isotopic fractionation for methane and lipids formed by methanogens using trimethylamine as their carbon source. Methanosarcina barkerii showed fractionation factors ({epsilon}) of 50.2{per_thousand} for conversion of TMA to methane and 20.2{per_thousand} for TMA-biomass. Moreover PME and phytanyl chains of K barkerii ether lipid were depleted by as much as 18{per_thousand} compared to biomass. For the Antarctic methanogen Methanococcoides burtonii we measured even greater e values of 71{per_thousand} (TMA-CH{sub 4}), 49.6{per_thousand} (TMA- biomass) and 79.9{per_thousand} (TMA-phytanyl ether). It should be noted that these E values represent maximum or near maximum values for non-limiting substrate concentrations and are significantly higher than those reported for aceticlastic methanogenesis (approx 21%.) or reduction of carbon dioxide (32 to 46{per_thousand}). Methylotrophic methanogenesis may be the source of extremely {sup 13}C-depleted methane in certain gas accumulations.

  14. C-isotopic fractionation during methylotrophic methanogenesis

    SciTech Connect

    Summons, R.E. ); Nichols, P.D.; Franzmann, P.D. )

    1996-01-01

    Methanogenesis from non-competitive substrates such as trimethylamine (TMA) may be quantitatively important in global methane budgets. This is because choline, glycine betaine and related compounds, precursors of TMA, are produced abundantly and ubiquitously by microbes, particularly those from marine and saline lacustrine environments. These substrates may source methane supersaturating oceanic seawater, possibly formed in anaerobic microhabitats (e.g. zooplankton guts and within particulates) and indicated by carbon isotopic analysis of abundant methanogen-derived hydrocarbons (e.g. 2, 6, 10, 15, 19-pentamethyleicosane, PME) found in recent and ancient marine sediments. In order to elaborate on these observations using cultured organisms we measured isotopic fractionation for methane and lipids formed by methanogens using trimethylamine as their carbon source. Methanosarcina barkerii showed fractionation factors ([epsilon]) of 50.2[per thousand] for conversion of TMA to methane and 20.2[per thousand] for TMA-biomass. Moreover PME and phytanyl chains of K barkerii ether lipid were depleted by as much as 18[per thousand] compared to biomass. For the Antarctic methanogen Methanococcoides burtonii we measured even greater e values of 71[per thousand] (TMA-CH[sub 4]), 49.6[per thousand] (TMA- biomass) and 79.9[per thousand] (TMA-phytanyl ether). It should be noted that these E values represent maximum or near maximum values for non-limiting substrate concentrations and are significantly higher than those reported for aceticlastic methanogenesis (approx 21%.) or reduction of carbon dioxide (32 to 46[per thousand]). Methylotrophic methanogenesis may be the source of extremely [sup 13]C-depleted methane in certain gas accumulations.

  15. Methanogenesis and Methanotrophy in Serpentinizing Systems

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  16. Methanogenesis and methanogenic pathways in a peat from subarctic permafrost.

    PubMed

    Metje, Martina; Frenzel, Peter

    2007-04-01

    Few studies have dealt so far with methanogenic pathways and populations in subarctic and arctic soils. We studied the effects of temperature on rates and pathways of CH4 production and on the relative abundance and structure of the archaeal community in a mildly acidic peat from a permafrost region in Siberia (67 degrees N). We monitored the production of CH4 and CO2 over time and measured the consumption of Fe(II), ethanol and volatile fatty acids. All experiments were performed with and without specific inhibitors [2-bromoethanesulfonate (BES) for methanogenesis and CH3F for acetoclastic methanogenesis]. The optimum temperature for methanogenesis was between 26 degrees C and 28 degrees C [4.3 micromol CH4 (g dry weight)(-1) day(-1)], but the activity was high even at 4 degrees C [0.75 micromol CH4 (g dry weight)(-1) day(-1)], constituting 17% of that at 27 degrees C. The population structure of archaea was studied by terminal restriction fragment length polymorphism analysis and remained constant over a wide temperature range. Acetoclastic methanogenesis accounted for about 70% of the total methanogenesis. Most 16S rRNA gene sequences clustered with Methanosarcinales, correlating with the prevalence of acetoclastic methanogenesis. In addition, sequences clustering with Methanobacteriales were recovered. Fe reduction occurred in parallel to methanogenesis. At lower and higher temperatures Fe reduction was not affected by BES. Because butyrate was consumed during methanogenesis and accumulated when methanogenesis was inhibited (BES and CH3F), it is proposed to serve as methanogenic precursor, providing acetate and H2 by syntrophic oxidation. In addition, ethanol and caproate occurred as intermediates. Because of thermodynamic constraints, homoacetogenesis could not compete with hydrogenotrophic methanogenesis. PMID:17359267

  17. Effect of gramicidin on methanogenesis by various methanogenic bacteria.

    PubMed

    Jarrell, K F; Hamilton, E A

    1985-07-01

    Methanogenesis by Methanobacterium thermoautotrophicum strains was extremely sensitive to gramicidin, total inhibition being observed at 0.2 mug/ml. In contrast, methane synthesis by Methanococcus voltae, Methanogenium marisnigri, Methanosarcina mazei, and Methanospirillum hungatei were resistant to the highest concentrations of gramicidin tested (40 mug/ml), although spheroplasts of Methanospirillum hungatei were extremely sensitive. Other species tested showed intermediate sensitivity to gramicidin, methanogenesis inhibition occurring at 4 to 20 mug/ml.

  18. Effect of Gramicidin on Methanogenesis by Various Methanogenic Bacteria

    PubMed Central

    Jarrell, Ken F.; Hamilton, Elizabeth A.

    1985-01-01

    Methanogenesis by Methanobacterium thermoautotrophicum strains was extremely sensitive to gramicidin, total inhibition being observed at 0.2 μg/ml. In contrast, methane synthesis by Methanococcus voltae, Methanogenium marisnigri, Methanosarcina mazei, and Methanospirillum hungatei were resistant to the highest concentrations of gramicidin tested (40 μg/ml), although spheroplasts of Methanospirillum hungatei were extremely sensitive. Other species tested showed intermediate sensitivity to gramicidin, methanogenesis inhibition occurring at 4 to 20 μg/ml. PMID:16346835

  19. Biogeochemical metabolic modeling of methanogenesis by Methanosarcina barkeri

    NASA Astrophysics Data System (ADS)

    Jensvold, Z. D.; Jin, Q.

    2015-12-01

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

  20. Inhibition of methanogenesis by chlorophenols: a kinetic approach.

    PubMed

    Puyol, D; Sanz, J L; Rodriguez, J J; Mohedano, A F

    2012-11-15

    Chlorophenols exert a crucial effect on the methanogenesis, considerably reducing both maximum methane potential and methanogenic rates. However, there is not enough information about the kinetic mechanism of chlorophenols toxicity on the methanogenesis, which is a key aspect for the control of the anaerobic digesters because of the sensitivity and the potential for energy recovery derived from methane release. The International Water Association-Anaerobic Digestion Model No. 1 (IWA-ADM1) can be adapted to a wide range of situations by updating or changing the equations in the model. The present study proposes a general kinetic model for methanogenesis. This model has been applied to predict the inhibition of methanogenesis by chlorophenols, and it can be used for updating the IWA-ADM1 when treating inhibitory compounds. The model was calibrated and validated using a wide broad of experimental sets of data of methane production by granular sludge in the presence of 2,4-dichlorophenol (24 DCP), 2,4,6-trichlorophenol (246TCP) and pentachlorophenol (PCP) in batch assays. A lag-phase of the effect of chlorophenols on the methanogenesis by non-adapted sludge was detected and modeled by the kinetic model proposed. In addition, the inhibitory effect of PCP was more pronounced on the acetoclastic methanogenesis than on the hydrogenotrophic one. Non-competitive and uncompetitive inhibition types were detected using 24 DCP and 246 TCP, whereas a suicide or irreversible inhibition type was observed in the case of PCP. Values of inhibition constants considerably varied depending on the chlorophenol used, between 45 mg24DCPL(-1), 41-51 mg246TCPL(-1) and 0.9-7.8 mgPCPL(-1). The higher toxicity of PCP is related with its hydrophobicity, which was determined by adsorption tests and using partition coefficients n-octanol/water. Modeling was accompanied by high statistical support in all cases, which confirmed the validation of the model proposed.

  1. Methanogenesis from wastewater stimulated by addition of elemental manganese.

    PubMed

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

    2015-08-05

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

  2. Methanogenesis from wastewater stimulated by addition of elemental manganese

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    1998-12-31

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

  4. Methanogenesis at low temperatures by microflora of tundra wetland soil.

    PubMed

    Kotsyurbenko, O R; Nozhevnikova, A N; Soloviova, T I; Zavarzin, G A

    1996-01-01

    Active methanogenesis from organic matter contained in soil samples from tundra wetland occurred even at 6 degrees C. Methane was the only end product in balanced microbial community with H2/CO2 as a substrate, besides acetate was produced as an intermediate at temperatures below 10 degrees C. The activity of different microbial groups of methanogenic community in the temperature range of 6-28 degrees C was investigated using 5% of tundra soil as inoculum. Anaerobic microflora of tundra wetland fermented different organic compounds with formation of hydrogen, volatile fatty acids (VFA) and alcohols. Methane was produced at the second step. Homoacetogenic and methanogenic bacteria competed for such substrates as hydrogen, formate, carbon monoxide and methanol. Acetogens out competed methanogens in an excess of substrate and low density of microbial population. Kinetic analysis of the results confirmed the prevalence of hydrogen acetogenesis on methanogenesis. Pure culture of acetogenic bacteria was isolated at 6 degrees C. Dilution of tundra soil and supply with the excess of substrate disbalanced the methanoigenic microbial community. It resulted in accumulation of acetate and other VFA. In balanced microbial community obviously autotrophic methanogens keep hydrogen concentration below a threshold for syntrophic degradation of VFA. Accumulation of acetate- and H2/CO2-utilising methanogens should be very important in methanogenic microbial community operating at low temperatures. PMID:8678482

  5. A systems level predictive model for global gene regulation of methanogenesis in a hydrogenotrophic methanogen

    PubMed Central

    Yoon, Sung Ho; Turkarslan, Serdar; Reiss, David J.; Pan, Min; Burn, June A.; Costa, Kyle C.; Lie, Thomas J.; Slagel, Joseph; Moritz, Robert L.; Hackett, Murray; Leigh, John A.; Baliga, Nitin S.

    2013-01-01

    Methanogens catalyze the critical methane-producing step (called methanogenesis) in the anaerobic decomposition of organic matter. Here, we present the first predictive model of global gene regulation of methanogenesis in a hydrogenotrophic methanogen, Methanococcus maripaludis. We generated a comprehensive list of genes (protein-coding and noncoding) for M. maripaludis through integrated analysis of the transcriptome structure and a newly constructed Peptide Atlas. The environment and gene-regulatory influence network (EGRIN) model of the strain was constructed from a compendium of transcriptome data that was collected over 58 different steady-state and time-course experiments that were performed in chemostats or batch cultures under a spectrum of environmental perturbations that modulated methanogenesis. Analyses of the EGRIN model have revealed novel components of methanogenesis that included at least three additional protein-coding genes of previously unknown function as well as one noncoding RNA. We discovered that at least five regulatory mechanisms act in a combinatorial scheme to intercoordinate key steps of methanogenesis with different processes such as motility, ATP biosynthesis, and carbon assimilation. Through a combination of genetic and environmental perturbation experiments we have validated the EGRIN-predicted role of two novel transcription factors in the regulation of phosphate-dependent repression of formate dehydrogenase—a key enzyme in the methanogenesis pathway. The EGRIN model demonstrates regulatory affiliations within methanogenesis as well as between methanogenesis and other cellular functions. PMID:24089473

  6. Kinetic investigation and mathematical modeling of methanogenesis of glucose

    SciTech Connect

    Kalyuzhnyy, S.V.; Sklyar, V.I.; Varfolomeyev, S.D.; Gachok, V.P.

    1991-12-31

    The kinetic regularities of anaerobic conversion of glucose, and intermediates of its decomposition (ethanol, butyrate, and acetate) by a microbial methanogenic association from anaerobic digester were investigated. Kinetic scheme for conversion of glucose is suggested, and the mathematical model based on the scheme is evolved. The model includes growth and metabolism of three kinds of microorganisms-acid producents, and acetate- and hydrogen-utilizing methane producents; of cell lysis with consequent fermentation of {open_quotes}died biomass{close_quotes} to acetate, hydrogen, and carbon dioxide; of induction and repression of the enzyme responsible for decomposition of butyrate, and for a number of regulations depending on the concentrations of intermediates in glucose metabolism. The values of parameters of the model have been calculated, sufficiently describing the experimental regularities. The numerical experiments have enabled us to reveal and describe the principal regulating factors of glucose methanogenesis.

  7. Bacterial methanogenesis in holocene sediments in the Baltic Sea

    SciTech Connect

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

    1981-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2005-01-01

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

  10. Characterization of an archaeal two-component system that regulates methanogenesis in Methanosaeta harundinacea.

    PubMed

    Li, Jie; Zheng, Xin; Guo, Xiaopeng; Qi, Lei; Dong, Xiuzhu

    2014-01-01

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

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

    USGS Publications Warehouse

    Oremland, Ronald S.; Polcin, Sandra

    1982-01-01

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

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

    EPA Science Inventory

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

  13. Alamethicin Suppresses Methanogenesis and Promotes Acetogenesis in Bioelectrochemical Systems

    PubMed Central

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

    2015-01-01

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

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

    USGS Publications Warehouse

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

    2016-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    DOE PAGES

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

    2015-11-18

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

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

    PubMed

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

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

  19. Crude-oil biodegradation via methanogenesis in subsurface petroleum reservoirs.

    PubMed

    Jones, D M; Head, I M; Gray, N D; Adams, J J; Rowan, A K; Aitken, C M; Bennett, B; Huang, H; Brown, A; Bowler, B F J; Oldenburg, T; Erdmann, M; Larter, S R

    2008-01-10

    Biodegradation of crude oil in subsurface petroleum reservoirs has adversely affected the majority of the world's oil, making recovery and refining of that oil more costly. The prevalent occurrence of biodegradation in shallow subsurface petroleum reservoirs has been attributed to aerobic bacterial hydrocarbon degradation stimulated by surface recharge of oxygen-bearing meteoric waters. This hypothesis is empirically supported by the likelihood of encountering biodegraded oils at higher levels of degradation in reservoirs near the surface. More recent findings, however, suggest that anaerobic degradation processes dominate subsurface sedimentary environments, despite slow reaction kinetics and uncertainty as to the actual degradation pathways occurring in oil reservoirs. Here we use laboratory experiments in microcosms monitoring the hydrocarbon composition of degraded oils and generated gases, together with the carbon isotopic compositions of gas and oil samples taken at wellheads and a Rayleigh isotope fractionation box model, to elucidate the probable mechanisms of hydrocarbon degradation in reservoirs. We find that crude-oil hydrocarbon degradation under methanogenic conditions in the laboratory mimics the characteristic sequential removal of compound classes seen in reservoir-degraded petroleum. The initial preferential removal of n-alkanes generates close to stoichiometric amounts of methane, principally by hydrogenotrophic methanogenesis. Our data imply a common methanogenic biodegradation mechanism in subsurface degraded oil reservoirs, resulting in consistent patterns of hydrocarbon alteration, and the common association of dry gas with severely degraded oils observed worldwide. Energy recovery from oilfields in the form of methane, based on accelerating natural methanogenic biodegradation, may offer a route to economic production of difficult-to-recover energy from oilfields.

  20. [Effect of ethanol on sulfate reduction and methanogenesis].

    PubMed

    Wang, Qi; Liu, Bo; Yan, Dong-Dong; Li, Song; Chen, Ze-Zhi

    2009-03-15

    Base on the different niche characteristics of sulfate-reducing bacteria (SRB), acidogenic bacteria (AB) and methane-producing bacteria (MPB), this experiment used two-stage anaerobic treatment and circular gas stripping. Sucrose and ethanol were used as organic substrate (COD = 6 000 mg x L(-1). The effect of ethanol concentration on sulfate reduction, COD removal and methanogenesis, the effect of sulfide stripping and the best recycle ratio were investigated respectively at different COD/SO4(2-) ratios. The results indicate that the addition of ethanol promotes SO4(2-) reduction, reduces inhibition of competition resulted from COD/SO4(2-) decreasing, and makes SRB, AB and MPB in good synergetic metabolism. The efficiency of the system was improved obviously after ethanol/SO4(2-) ratio enhanced from 0 to 2. When the ratios of COD/SO4(2-) were 12, 6 and 4, SO4(2-) reduction efficiencies increased from 7.7%, 8.1%, 14.1% to 84.7%, 87.6%, 82.5%, COD removal efficiencies increased from 83.3%, 76.5%, 69.6% to 92.8%, 93.5%, 89.7%, and CH4/COD increased from 225.7, 204.6, 178.6 mL x g(-1) to 278.5, 253.7, 236.1 mL x g(-1), respectively. Dilution at a recycle ratio of 10 and stripping 30%-55% sulfide controlled sulfide concentrations less than 27.8, 38.4, 52.4 mg x L(-1), which inhibited effectively the toxicity of H2S. But higher recycle ratio (r = 20) made substrate gradient too little and SO4(2-) reduction efficiency reduced, while lower recycle ratio (r = 5) made sludge bed shrunken and COD removal efficiency reduced.

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

    PubMed Central

    Ungerfeld, Emilio M.

    2015-01-01

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

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

    PubMed

    Ungerfeld, Emilio M

    2015-01-01

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

  3. Methanogenesis affected by the co-occurrence of iron(III) oxides and humic substances.

    PubMed

    Zhou, Shungui; Xu, Jielong; Yang, Guiqin; Zhuang, Li

    2014-04-01

    Iron oxides and humic substances (humics) have substantial effects on biochemical processes, such as methanogenesis, due to their redox reactivity and ubiquitous presence. This study aimed to investigate how methanogenesis is affected by the common occurrence of these compounds, which has not been considered to date. The experiment was conducted with anoxic paddy soil microcosms receiving a humics surrogate compound (anthraquinone-2,6-disulfonate, AQDS) and three iron(III) oxides (ferrihydrite, hematite, and magnetite) differing in crystallinity and conductivity. Ferrihydrite suppressed methanogenesis, whereas AQDS, hematite, and magnetite facilitated methanogenesis. CH4 production in co-occurring ferrihydrite + AQDS, hematite + AQDS, and magnetite + AQDS cultures was 4.1, 1.3, and 0.9 times greater than the corresponding cultures without AQDS, respectively. Syntrophic cooperation between Geobacter and Methanosarcina occurred in the methanogenesis-facilitated cultures. Experimental results suggested that the conductive characteristics of iron(III) oxides was an important factor determining the methanogenic response to the co-occurrence of iron(III) oxides and humics in anaerobic paddy soil. This work indicated that the type of iron(III) oxides may significantly affect carbon cycling under anoxic conditions in natural wetlands.

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

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

    PubMed

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

    2015-01-01

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

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

    USGS Publications Warehouse

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

    2004-01-01

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

  9. Effect of tween surfactants on methanogenesis and microbial reductive dechlorination of hexachlorobenzene

    SciTech Connect

    Yeh, D.H.; Pennell, K.D.; Pavlostathis, S.G.

    1999-07-01

    The effect of nine Tween surfactants (polyoxyethylene sorbitan fatty acid esters) on methanogenesis and the microbial reductive dechlorination of hexachlorobenzene (HCB) was examined using three anaerobic, HCB-dechlorinating mixed cultures, one glucose fed and two lactate fed, that were derived from contaminated estuarine sediments. The two lactate-fed cultures differed significantly in their metabolic activity, especially with respect to the rate and extent of HCB reductive dechlorination. The objective of the study was to screen and select biologically compatible surfactants for use in subsequent research on surfactant-enhanced bioavailability of sorbed-phase chlorinated organic contaminants. Addition of the Tween surfactants resulted in lower rates of methanogenesis and HCB dechlorination compared with the control for both the glucose-fed culture and the lactate-fed culture, which exhibited a high metabolic activity. Tween-61 and -65 exhibited the lowest inhibition of HCB dechlorination at initial surfactant concentrations of 200 and 1,000 mg/L. On the other hand, the Tween surfactants, especially Tween-81 and -85, enhanced the rates of both methanogenesis and HCB dechlorination when the low metabolic activity lactate-fed culture was used. The observed rate enhancements may be attributed to bacterial cell membrane modification by the surfactants. Attempts to correlate methanogenesis rates to surfactant properties were not successful. In general, increased surfactant concentrations resulted in lower rate and extent of HCB dechlorination. Although HCB dechlorination was completely inhibited at a surfactant concentration of 1,000 mg/L, the extent of methanogenesis was not affected. Results from this study demonstrate that despite compositional similarities among the Tween surfactants, their effects on biological activities, such as methanogenesis and reductive dechlorination, can differ significantly.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  11. Paleohydrologic controls on methanogenesis in organic-rich saline aquifers

    NASA Astrophysics Data System (ADS)

    McIntosh, J.; Petsch, S.; Schlegel, M.; Osborn, S.

    2007-12-01

    Freshwater recharge into the margins of sedimentary basins, during periods of continental glaciation, stimulated microbial methane generation in organic-rich shales and coal beds, by significantly diluting the ambient formation water salinity. Subglacial recharge may have also transported microorganisms and nutrients into the subsurface environment. Methane is generated by a diverse consortium of both acetoclastic and CO2-reducing methanogenic Archaea, and adsorbed onto the organic matter. These shallow methane accumulations account for ~20% of the total U.S. natural gas production. Anaerobic microbial metabolism of shales and coals is in part controlled by the volume of pore waters and fluid composition, amount of extractable organic matter and intermediary substrates, reservoir temperature, and mass transport processes that provide essential rock-derived nutrients and organic acids. Methanogens are most active in low salinity environments (<2.5 mol/L Cl) with no SO4, and at the interfaces between confining units and adjacent aquifers where diffusion dominates. Microbial degradation of organic matter generates high alkalinity concentrations, which may induce calcite precipitation in shale fractures and coal cleats, which can in turn modify the subsurface hydrology. Microbial methanogenesis also imparts a strong control on the cycling of carbon, H2, and other elements in the subsurface environment. This presentation will focus on the timing of recharge and establishment of microbial communities within the Upper Devonian black shales, Pennsylvanian coal beds, and overlying glacial drift in the Illinois Basin, and the importance of continued groundwater flow on active methane generation and accumulation. There is an approximately 65-70 per mil depletion in 13C of CH4, relative to the precursor CO2 in the Upper Devonian shales, Pennsylvanian coals, and glacial drift. In addition, there is a linear correlation between the dD values of co- produced formation waters and

  12. Control of interspecies electron flow during anaerobic digestion: significance of formate transfer versus hydrogen transfer during syntrophic methanogenesis in flocs. [Methanobacterium formicicum; Desulfovibrio vulgaris

    SciTech Connect

    Thiele, J.H.; Zeikus, J.G.

    1988-01-01

    Microbial formate production and consumption during syntrophic conversion of ethanol or lactate to methane was examined in purified flocs and digestor contents obtained from a whey-processing digestor. Formate production by digestor contents or purified digestor flocs was dependent on CO/sub 2/ and either ethanol or lactate but not H/sub 2/ gas as an electron donor. Floc preparations accumulated fourfold-higher levels of formate (40 ..mu..M) than digestor contents, and the free flora was the primary site for formate cleavage to CO/sub 2/ and H/sub 2/ (90 ..mu..M formate per h). Inhibition of methanogenesis by CHCl/sub 3/ resulted in formate accumulation and suppression of syntrophic ethanol oxidation. H/sub 2/ gas was an insignificant intermediary metabolite of syntrophic ethanol conversion by flocs, and it exogenous addition neither stimulated methanogenes nor inhibited the initial rate of ethanol oxidation. These results demonstrated that >90% of the syntrophic ethanol conversion to methane by mixed cultures containing primarily Desulfovibrio vulgaris and Methanobacterium formicicum was mediated via interspecies formate transfer and the <10% was mediated via interspecies H/sub 2/ transfer. The results are discussed in relation to biochemical thermodynamics. A model is presented which describes the dynamics of a bicarbonate-formate electron shuttle mechanism for control of carbon and electron flow during syntrophic methanogenesis and provides a novel mechanism for energy conservation by syntrophic acetogens.

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

    SciTech Connect

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

    2015-11-18

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

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

    EPA Science Inventory

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

  15. Improved hydrogen production in the microbial electrolysis cell by inhibiting methanogenesis using ultraviolet irradiation.

    PubMed

    Hou, Yanping; Luo, Haiping; Liu, Guangli; Zhang, Renduo; Li, Jiayi; Fu, Shiyu

    2014-09-01

    Methanogenesis inhibition is essential for the improvement of hydrogen (H2) yield and energy recovery in the microbial electrolysis cell (MEC). In this study, ultraviolet (UV) irradiation was proposed as an efficient method for methanogenesis control in a single chamber MEC. With 30 cycles of operation with UV irradiation in the MEC, high H2 concentrations (>91%) were maintained, while without UV irradiation, CH4 concentrations increased significantly and reached up to 94%. In the MEC, H2 yields ranged from 2.87 ± 0.03 to 3.70 ± 0.11 mol H2/mol acetate with UV irradiation and from 3.78 ± 0.12 to 0.03 ± 0.004 mol H2/mol acetate without UV irradiation. Average energy efficiencies from the UV-irradiated MEC were 1.5 times of those without UV irradiation. Energy production from the MEC without UV irradiation was a negative energy yield process because of large amount of CH4 produced over time, which was mainly attributable to cathodic hydrogenotrophic methanogenesis. Our results clearly showed that UV irradiation could effectively inhibit methanogenesis and improve MEC performance to produce H2.

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

    EPA Science Inventory

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-01-01

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

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

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-02-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2015-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2013-09-01

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

  4. Suppression of methanogenesis for hydrogen production in single-chamber microbial electrolysis cells using various antibiotics.

    PubMed

    Catal, Tunc; Lesnik, Keaton Larson; Liu, Hong

    2015-01-01

    Methanogens can utilize the hydrogen produced in microbial electrolysis cells (MECs), thereby decreasing the hydrogen generation efficiency. However, various antibiotics have previously been shown to inhibit methanogenesis. In the present study antibiotics, including neomycin sulfate, 2-bromoethane sulfonate, 2-chloroethane sulfonate, 8-aza-hypoxanthine, were examined to determine if hydrogen production could be improved through inhibition of methanogenesis but not hydrogen production in MECs. 1.1mM neomycin sulfate inhibited both methane and hydrogen production while 2-chloroethane sulfonate (20mM), 2-bromoethane sulfonate (20mM), and 8-aza-hypoxanthine (3.6mM) can inhibited methane generation and with concurrent increases in hydrogen production. Our results indicated that adding select antibiotics to the mixed species community in MECs could be a suitable method to enhance hydrogen production efficiency.

  5. [Sulfate reduction and methanogenesis in the Shira and Shunet meromictic lakes (Khakass Republic, Russia)].

    PubMed

    Kallistova, A Iu; Kevbrina, M V; Pimenov, N V; Rusanov, I I; Rogozin, D Iu; Wehrli, B; Nozhevnikova, A N

    2006-01-01

    The biogeochemical and molecular biological study of the chemocline and sediments of saline meromictic lakes Shira and Shunet (Khakass Republic, Russia) was performed. A marked increase in the rates of sulfate reduction and methanogenesis was revealed at the medium depths of the chemocline. The rates of these processes in the bottom sediments decreased with depth. The numbers of Bacteria, Archaea, and of sulfate-reducing bacteria (SRB) were determined by fluorescence in situ hybridization with rRNA specific oligonucleotide probes labeled with horseradish peroxidase and subsequent tyramide signal amplification. In the chemocline, both the total microbial numbers and those of Bacteria were shown to increase with depth. The archaea and SRB were present in almost equal numbers. In the lake sediments, a drastic decrease in microbial numbers with depth was revealed. SRB were found to prevail in the upper sediment layer and archaea in the lower one. This finding correlates with the measured rates of sulfate reduction and methanogenesis. PMID:17205809

  6. 45 CFR 650.6 - Awards not primarily for research.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

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

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

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

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

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

  9. Making primarily professional terms more comprehensible to the lay audience.

    PubMed

    Goryachev, Sergey; Zeng-Treitler, Qing; Smith, Catherine Arnott; Browne, Allen C; Divita, Guy; Keselman, Alla; Leroy, Gondy; Figueroa, Rosa

    2008-11-06

    Certain texts, such as clinical reports and clinical trial records, are written by professionals for professionals while being increasingly accessed by lay people. To improve the comprehensibility of such documents to the lay audience, we conducted a pilot study to analyze terms used primarily by health professionals, and explore ways to make them more comprehensible to lay people.

  10. Nitrate and nitrite inhibition of methanogenesis during denitrification in granular biofilms and digested domestic sludges.

    PubMed

    Banihani, Qais; Sierra-Alvarez, Reyes; Field, James A

    2009-11-01

    Anaerobic bioreactors that can support simultaneous microbial processes of denitrification and methanogenesis are of interest to nutrient nitrogen removal. However, an important concern is the potential toxicity of nitrate (NO(3) (-)) and nitrite (NO(2) (-)) to methanogenesis. The methanogenic toxicity of the NO (x) (-) compounds to anaerobic granular biofilms and municipal anaerobic digested sludge with two types of substrates, acetate and hydrogen, was studied. The inhibition was the severest when the NO (x) (-) compounds were still present in the media (exposure period). During this period, 95% or greater inhibition of methanogenesis was evident at the lowest concentrations of added NO(2) (-) tested (7.6-10.2 mg NO(2) (-)-N l(-1)) or 8.3-121 mg NO(3) (-)-N l(-1) of added NO(3) (-), depending on substrate and inoculum source. The inhibition imparted by NO(3) (-) was not due directly to NO(3) (-) itself, but instead due to reduced intermediates (e.g., NO(2) (-)) formed during the denitrification process. The toxicity of NO (x) (-) was found to be reversible after the exposure period. The recovery of activity was nearly complete at low added NO (x) (-) concentrations; whereas the recovery was only partial at high added NO (x) (-) concentrations. The recovery is attributed to the metabolism of the NO (x) (-) compounds. The assay substrate had a large impact on the rate of NO(2) (-) metabolism. Hydrogen reduced NO(2) (-) slowly such that NO(2) (-) accumulated more and as a result, the toxicity was greater compared to acetate as a substrate. The final methane yield was inversely proportional to the amount of NO (x) (-) compounds added indicating that they were the preferred electron acceptors compared to methanogenesis.

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

    NASA Astrophysics Data System (ADS)

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

    2010-05-01

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

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

    PubMed

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

    2015-04-01

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

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

    PubMed

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

    2015-04-01

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

  14. Methanogenesis at extremely haloalkaline conditions in the soda lakes of Kulunda Steppe (Altai, Russia).

    PubMed

    Sorokin, Dimitry Y; Abbas, Ben; Geleijnse, Mitchell; Pimenov, Nikolai V; Sukhacheva, Marina V; van Loosdrecht, Mark C M

    2015-04-01

    Microbial methanogenesis at extreme conditions of saline alkaline soda lakes has, so far, been poorly investigated. Despite the obvious domination of sulfidogenesis as the therminal anaerobic process in the hypersaline soda lakes of Kulunda Steppe (Altai, southwestern Siberia), high concentrations of methane were detected in the anaerobic sediments. Potential activity measurements with different substrates gave results significantly deviating from what is commonly found in hypersaline habitats with neutral pH. In particular, not only a non-competitive methylotrophic pathway was active, but also lithotrophic and, in some cases, even acetate-dependent methanogenesis was found to be present in hypersaline soda lake sediments. All three pathways were functioning exclusively within the alkaline pH range between 8 and 10.5, while the salt concentration was the key factor influencing the activity. Methylotrophic and, to a lesser extent, lithotrophic methanogenesis were active up to soda-saturating conditions (4 M total Na(+)). Acetate-dependent methanogenesis was observed at salinities below 3 M total Na(+). Detection of methanogens in sediments using the mcrA gene as a functional marker demonstrated domination of methylotrophic genera Methanolobus and Methanosalsum and lithotrophic Methanocalculus. In a few cases, acetoclastic Methanosaeta was detected, as well as two deep lineage methanogens. Cultivation results corresponded well to the mcrA-based observations. Enrichments for natronophilic methylotrophic methanogens resulted in isolation of Methanolobus strains at moderate salinity, while at salt concentrations above 2 M Na(+) a novel member of the genus Methanosalsum was dominating. Enrichments with H2 or formate invariably resulted in domination of close relatives of Methanocalculus natronophilus. Enrichments with acetate at low salt concentration yielded two acetoclastic alkaliphilic Methanosaeta cultures, while at salinity above 1 M Na(+) syntrophic associations

  15. Methanogenesis at extremely haloalkaline conditions in the soda lakes of Kulunda Steppe (Altai, Russia).

    PubMed

    Sorokin, Dimitry Y; Abbas, Ben; Geleijnse, Mitchell; Pimenov, Nikolai V; Sukhacheva, Marina V; van Loosdrecht, Mark C M

    2015-04-01

    Microbial methanogenesis at extreme conditions of saline alkaline soda lakes has, so far, been poorly investigated. Despite the obvious domination of sulfidogenesis as the therminal anaerobic process in the hypersaline soda lakes of Kulunda Steppe (Altai, southwestern Siberia), high concentrations of methane were detected in the anaerobic sediments. Potential activity measurements with different substrates gave results significantly deviating from what is commonly found in hypersaline habitats with neutral pH. In particular, not only a non-competitive methylotrophic pathway was active, but also lithotrophic and, in some cases, even acetate-dependent methanogenesis was found to be present in hypersaline soda lake sediments. All three pathways were functioning exclusively within the alkaline pH range between 8 and 10.5, while the salt concentration was the key factor influencing the activity. Methylotrophic and, to a lesser extent, lithotrophic methanogenesis were active up to soda-saturating conditions (4 M total Na(+)). Acetate-dependent methanogenesis was observed at salinities below 3 M total Na(+). Detection of methanogens in sediments using the mcrA gene as a functional marker demonstrated domination of methylotrophic genera Methanolobus and Methanosalsum and lithotrophic Methanocalculus. In a few cases, acetoclastic Methanosaeta was detected, as well as two deep lineage methanogens. Cultivation results corresponded well to the mcrA-based observations. Enrichments for natronophilic methylotrophic methanogens resulted in isolation of Methanolobus strains at moderate salinity, while at salt concentrations above 2 M Na(+) a novel member of the genus Methanosalsum was dominating. Enrichments with H2 or formate invariably resulted in domination of close relatives of Methanocalculus natronophilus. Enrichments with acetate at low salt concentration yielded two acetoclastic alkaliphilic Methanosaeta cultures, while at salinity above 1 M Na(+) syntrophic associations

  16. Use of some novel alternative electron sinks to inhibit ruminal methanogenesis.

    PubMed

    Ungerfeld, Emilio M; Rust, Steven R; Burnett, Robert

    2003-01-01

    Several compounds were evaluated in vitro as alternative electron sinks to ruminal methanogenesis. They were incubated with ruminal fluid, buffer mixture, and finely ground alfalfa hay for 24 h, at 0, 6, 12, and 18 mM initial concentrations. The propionate enhancer oxaloacetic acid, the butyrate enhancer beta-hydroxybutyrate, and the butyrate unsaturated analog 3-butenoic acid were ineffective in decreasing methanogenesis. Nevertheless, beta-hydroxybutyrate increased apparent fermentation of the alfalfa hay substrate from 58.0 to 63.4%, and 3-butenoic acid seemed to increase it from 62.0 to 73.7%. Almost all of added oxaloacetic acid disappeared during the incubation, while only between 30.3 and 53.4% of beta-hydroxybutyrate disappeared. The butyrate enhancers acetoacetate and crotonic acid, and the butyrate unsaturated analog 2-butynoic acid, decreased methanogenesis by a maximum of 18,9 and 9%, respectively. Crotonic acid at 18 mM initial concentration seemed to increase the substrate apparent fermentation from 57.0 to 68.2%. Between 78.6 and 100% of acetoacetate disappeared during the incubation. The propionate unsaturated analog propynoic acid, and the unsaturated ester ethyl 2-butynoate, decreased methanogenesis by a maximum of 76 and 79%, respectively. Less than 5% of propynoic acid disappeared. The substrate apparent fermentation was decreased by propynoic acid from 62.0 to 57.4%, and seemed to have been decreased by ethyl 2-butynoate from 62.0 to 29.3%. More accurate measurements of the disappearance of some of the compounds studied are needed to better understand how they are metabolized and how they affect fermentation.

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

    PubMed

    Blodau, Christian; Siems, Melanie; Beer, Julia

    2011-12-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    USGS Publications Warehouse

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

    2003-01-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

  4. Acetoclastic methanogenesis is likely the dominant biochemical pathway of palmitate degradation in the presence of sulfate.

    PubMed

    Lv, Lei; Mbadinga, Serge Maurice; Wang, Li-Ying; Liu, Jin-Feng; Gu, Ji-Dong; Mu, Bo-Zhong; Yang, Shi-Zhong

    2015-09-01

    Long chain fatty acids (LCFAs) are important intermediates in the anaerobic degradation of n-alkanes. In order to find out the biochemical processes involved in the degradation of LCFAs, palmitate (a typical LCFA) was used as a substrate, and low-temperature oilfield production fluids were used as a source of microorganisms to establish two anaerobic systems, one with addition of sulfate as exogenous electron acceptor (SP), another without exogenous electron acceptor (MP) and both incubated at room temperature. After more than 2 years of incubation, about 48 and 57.4% of the palmitate were degraded in samples of MP and SP, respectively. Methane production reached 1408 and 1064 μmol for MP and SP, respectively. Clone libraries of archaeal 16S rRNA genes showed that the predominant archaea in the sulfate-amended cultures (SP) was Methanosaeta whereas Methanocalculus dominated the culture without addition of exogenous sulfate (MP). This observation shows that palmitate could be biodegraded into methane through β-oxidation and acetoclastic methanogenesis in the presence of with or without sulfate. The high occurrence of Methanosaeta in the sulfate-amended system indicates that acetoclastic methanogenesis was not inhibited/little affected by the addition of sulfate. Acetoclastic methanogenesis might be the predominant biochemchimcal pathway of methane generation in enrichment cultures amended with sulfate. These results shed light on alternative methanogenic pathways in the presence of sulfate.

  5. Improving performance of microbial fuel cell while controlling methanogenesis by Chaetoceros pretreatment of anodic inoculum.

    PubMed

    Rajesh, P P; Jadhav, D A; Ghangrekar, M M

    2015-03-01

    Loss of substrate due to methanogenesis reduces Coulombic efficiency (CE) of the microbial fuel cell (MFC) significantly. Hexadecatrienoic acid present in the marine algae Chaetoceros inhibits the growth of methanogenic archaea. Influence of Chaetoceros pre-treated mixed anaerobic sludge on the electrogenic activity of MFC was evaluated. A MFC inoculated with Chaetoceros pre-treated mixed anaerobic sludge demonstrated maximum CE of 45.18%, with volumetric power density of 21.43W/m(3) and current density of 93A/m(3). Cyclic voltammetry indicated higher electron discharge on the anode surface due to suppression of methanogenesis. Tafel analysis also showed a higher exchange current density and a lower Tafel slope and charge transfer resistance, indicating advantage of this pre-treatment method in reducing the cell internal losses. A 60% reduction in specific methanogenic activity was observed in anaerobic sludge pre-treated with Chaetoceros; emphasizing significance of this pretreatment for suppressing methanogenesis and its utility for enhancing electricity generation in MFC.

  6. iDriving (Intelligent Driving)

    2012-09-17

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

  7. Careers in virology: teaching at a primarily undergraduate institution.

    PubMed

    Kushner, David B

    2014-10-01

    A faculty position at a primarily undergraduate institution requires working with undergraduates in both the classroom and the research lab. Graduate students and postdoctoral fellows who are interested in such a career should understand that faculty at these institutions need to teach broadly and devise research questions that can be addressed safely and with limited resources compared to a research I university. Aspects of, and ways to prepare for, this career will be reviewed herein.

  8. Microbial Methanogenesis In Laboratory Incubations Of Coal: Implications For A Sustainable Energy Resource In Subsurface Coalbeds

    NASA Astrophysics Data System (ADS)

    Harris, S. H.; Barker, C. E.; Smith, R. L.

    2005-12-01

    Methane desorbed from subsurface coalseams contributes about 8% of the total natural gas produced in the US. This value is expected to increase over the next several years as a growing proportion of energy demands are supplied from unconventional reservoirs. Isotopic analyses of gas samples from several geographically separate coalbeds indicates a substantial proportion of the sorbed methane is biogenic in origin. Furthermore, previous studies have shown the ability of microbial consortia to degrade coal in aerobic laboratory incubations. These findings suggests the stimulation of microbial methane production in subsurface coals may provide a sustainable source of domestic energy. To address this prospect, we assessed the ability of indigenous microbial populations to produce methane in coal maintained under anaerobic conditions in the laboratory and investigated factors that influenced the rate and extent of the process. Several freshly collected coals of different rank were examined for their ability to support methanogenesis in mineral medium alone or amended with different nutrients such as hydrogen (4 kPa), formate (20 mM), or acetate (25mM). Microbial methane production was distinguished from abiotic desorption by subtracting methane generated in replicate incubations that contained bromoethanesulfonic acid (5 mM), an inhibitor of methanogenesis. The extent and rate of methane production varied among the different coals. A relatively shallow (400 m), immature coal exhibited a rate of 700 nmole CH4*day-1*g coal-1, a value comparable to previous observations of contaminated sediments. Methane production was negligible in a deeper, relatively mature (650 m) coal obtained from the same borehole although the same material exhibited a rate of about 80 nmole CH4*day-1*g coal-1 after a formate amendment. In contrast, hydrogen proved to be ineffective as a methanogenic substrate, although this electron donor was rapidly consumed in coal incubations. A filter

  9. Drugged Driving

    MedlinePlus

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

  10. Impaired Driving

    MedlinePlus

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

  11. Amphotericin primarily kills yeast by simply binding ergosterol

    PubMed Central

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

    2012-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

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

  14. Potential functional gene diversity involved in methanogenesis and methanogenic community structure in Indian buffalo (Bubalus bubalis) rumen.

    PubMed

    Singh, Krishna M; Patel, Amrutlal K; Shah, Ravi K; Reddy, Bhaskar; Joshi, Chaitanya G

    2015-08-01

    Understanding the methanogen community structure and methanogenesis from Bubalus bubalis in India may be beneficial to methane mitigation. Our current understanding of the microbial processes leading to methane production is incomplete, and further advancement in the knowledge of methanogenesis pathways would provide means to manipulate its emission in the future. In the present study, we evaluated the methanogenic community structure in the rumen as well as their potential genes involved in methanogenesis. The taxonomic and metabolic profiles of methanogens were assessed by shotgun sequencing of rumen metagenome by Ion Torrent semiconductor sequencing. The buffalo rumen contained representative genera of all the families of methanogens. Members of Methanobacteriaceae were found to be dominant, followed by Methanosarcinaceae, Methanococcaceae, Methanocorpusculaceae, and Thermococcaceae. A total of 60 methanogenic genera were detected in buffalo rumen. Methanogens related to the genera Methanobrevibacter, Methanosarcina, Methanococcus, Methanocorpusculum, Methanothermobacter, and Methanosphaera were predominant, representing >70 % of total archaeal sequences. The metagenomic dataset indicated the presence of genes involved in the methanogenesis and acetogenesis pathways, and the main functional genes were those of key enzymes in the methanogenesis. Sequences related to CoB--CoM heterodisulfide reductase, methyl coenzyme M reductase, f420-dependent methylenetetrahydromethanopterin reductase, and formylmethanofuran dehydrogenase were predominant in rumen. In addition, methenyltetrahydrofolate cyclohydrolase, methylenetetrahydrofolate dehydrogenase, 5,10-methylenetetrahydrofolate reductase, and acetyl-coenzyme A synthetase were also recovered. PMID:25663664

  15. Pile Driving

    NASA Technical Reports Server (NTRS)

    1987-01-01

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

  16. Polar Direct Drive

    NASA Astrophysics Data System (ADS)

    Skupsky, S.

    2003-10-01

    Direct drive offers the potential of higher target gain on the National Ignition Facility (NIF) than x-ray drive: The initial direct-drive target design had a 1-D gain of 45 and consisted primarily of a pure cryogenic DT shell. Using the expected levels of target and laser nonuniformities for the NIF, two-dimensional (2-D) hydrodynamic simulations predicted target gains around 30.(P.W. McKenty et al.), Phys. Plasmas 8, 2315 (2001). More-recent designs have shown that higher target gains could be obtained by replacing a portion of the DT shell with ``wetted'' CH foam and by using adiabat shaping: (1) Higher-Z material (C) in the foam increases laser absorption by about 40% (from 60% absorption to 85%).(S. Skupsky et al.), in Inertial Fusion Sciences and Applications 2001, edited by K. Tanaka et al. (Elsevier, Paris, 2002), p. 240. (2) Adiabat shaping allows the main portion of the fuel to be placed on a lower adiabat without compromising target stability.(V.N. Goncharov et al.), Phys. Plasmas 10, 1906 (2003). These direct-drive concepts can be tested on the NIF, long before that facility is converted to a direct-drive (spherically symmetric) irradiation configuration. Using the NIF x-ray-drive beam configuration, some of the near-polar beams could be pointed to better illuminate the target's equator. These more-oblique, equatorial beams will have lower absorption and reduced drive efficiency than the polar beams. One strategy to compensate for the difference in polar and equatorial drive is to reduce the irradiation at the poles and employ different pulse shapes to accommodate the time-dependent variations in drive and absorption. This concept of polar direct drive (PDD) has been studied using the 2-D hydrocode DRACO to determine the requirements for achieving ignition and moderate target gain for the NIF. Experiments on the OMEGA laser will examine the effects of oblique irradiation on target drive. Results of simulations for different direct-drive target designs

  17. A new model linking atmospheric methane sources to Pleistocene glaciation via methanogenesis in sedimentary basins

    NASA Astrophysics Data System (ADS)

    Formolo, M. J.; Salacup, J. M.; Petsch, S. T.; Martini, A. M.; Nüsslein, K.

    2008-02-01

    Methane (CH4) is an important greenhouse gas and amplifier ofclimate change. However, the causes of atmospheric CH4 variationsover glacial-interglacial cycles remain unresolved. We proposethat microbial methanogenesis along the shallow margins of sedimentarybasins provides a source of atmospheric CH4 temporally connectedwith both advance and retreat of continental ice sheets. Extensivebiodegradation of hydrocarbons in the Antrim Shale Formation,Michigan, United States, is associated with an active subsurfaceconsortium of fermentative and methanogenic microorganisms.This activity was initially stimulated when saline formationwaters were diluted by meltwater derived from overriding Pleistoceneice sheets. During glaciation, CH4 produced by this communityaccumulated in the shale at a rate of 1 Tg CH4 per 1000 yr asa result of ice coverage and increased hydrostatic pressure.We estimate that at present the Antrim Shale contains only 12%-25%of the cumulative mass of CH4 generated in the shale over thePleistocene, indicating that CH4 that had accumulated duringglaciation was subsequently released following ice-sheet retreat.While release from the Antrim Shale represents only a smallpart of the global CH4 budget, when extended to other glaciatedsedimentary basins, subsurface methanogenesis may generate asubstantial, previously unrecognized source of atmospheric CH4during deglaciation.

  18. Methanogenesis in hypersaline ecosystems, and isolation and characterization of eight halophilic, methanogenic bacteria

    SciTech Connect

    Mathrani, I.M.

    1989-01-01

    The present ecological study of methanogenesis in hypersaline ecosystems focused on anaerobic sediment samples collected from several parts of the world. Inocula from solar salterns and natural hypersaline systems were examined for their ability to use catabolic substrates and for conditions which supported methanogenesis. Eight strictly anaerobic, halophilic, methane-producing Archaeobacteria were isolated from enrichment cultures inoculated with samples from hypersaline systems. The physiological and ecological characteristics of the isolates were examined and their phenotypic relatedness to each other and existing species of halophilic methanogens was discussed. The methanogenic, sulfate-reducing, and cellulolytic, halophilic bacteria from sediments of Lake Retba, Senegal were enumerated in depth profiles of sediment core samples. The catabolic substrates and environmental conditions for best growth of each bacterial group were determined. Trimethylamine, dimethylamine, methylamine, methanol, and sometimes dimethylsulfide were used as substrates for growth of methanogenic enrichment cultures and the eight isolates; hydrogen, acetate, or secondary alcohols did not support growth of methanogens. Hydrogen, formate, and lactate supported the growth of halophilic sulfate-reducing bacteria.

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

    SciTech Connect

    Paterek, J.R.

    1983-01-01

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

  20. Controlling methanogenesis and improving power production of microbial fuel cell by lauric acid dosing.

    PubMed

    Rajesh, P P; Noori, Md T; Ghangrekar, M M

    2014-01-01

    Methanogens compete with anodophiles for substrate and thus reduce the power generation and coulombic efficiency (CE) of the microbial fuel cell (MFC). Performance of a baked clayware membrane MFC inoculated with mixed anaerobic sludge pretreated with lauric acid was investigated in order to enhance power recovery by controlling methanogenesis. In the presence of lauric acid pretreated inoculum, MFC produced maximum volumetric power density of 4.8 W/m(3) and the CE increased from 3.6% (for untreated inoculum) to 11.6%. Cyclic voltammetry (CV) and electro-kinetic evaluation indicated a higher bio-catalytic activity at the anode of the MFC inoculated with lauric acid pretreated sludge. With the lauric acid pretreated inoculum a higher catalytic current of 114 mA, exchange current density of 40.78 mA/m(2) and lower charge transfer resistance of 0.00016 Ωm(2) were observed during oxidation at the anode. Addition of lauric acid significantly achieved suppression of methanogenesis and enhanced the sustainable power generation of MFC by 3.9 times as compared with control MFC inoculated with sludge without any pretreatment. PMID:25353941

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

    PubMed Central

    Ungerfeld, Emilio M.

    2015-01-01

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

  2. Immunization against Rumen Methanogenesis by Vaccination with a New Recombinant Protein.

    PubMed

    Zhang, Litai; Huang, Xiaofeng; Xue, Bai; Peng, Quanhui; Wang, Zhisheng; Yan, Tianhai; Wang, Lizhi

    2015-01-01

    Vaccination through recombinant proteins against rumen methanogenesis provides a mitigation approach to reduce enteric methane (CH4) emissions in ruminants. The objective of present study was to evaluate the in vivo efficacy of a new vaccine candidate protein (EhaF) on methanogenesis and microbial population in the rumen of goats. We amplified the gene mru 1407 encoding protein EhaF using fresh rumen fluid samples of mature goats and successfully expressed recombinant protein (EhaF) in Escherichia coli Rosetta. This product was evaluated using 12 mature goats with half for control and other half injected with 400ug/goat the purified recombinant protein in day 1 and two subsequent booster immunizations in day 35 and 49. All measurements were undertaken from 63 to 68 days after the initial vaccination, with CH4 emissions determined using respiration calorimeter chambers. The results showed that the vaccination caused intensive immune responses in serum and saliva, although it had no significant effect on total enteric CH4 emissions and methanogen population in the rumen, when compared with the control goats. However, the vaccination altered the composition of rumen bacteria, especially the abundance of main phylum Firmicutes and genus Prevotella. The results indicate that protein EhaF might not be an effective vaccine to reduce enteric CH4 emissions but our vaccine have potential to influence the rumen ecosystem of goats. PMID:26445479

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

    PubMed

    Ungerfeld, Emilio M

    2015-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  5. Immunization against Rumen Methanogenesis by Vaccination with a New Recombinant Protein

    PubMed Central

    Zhang, Litai; Huang, Xiaofeng; Xue, Bai; Peng, Quanhui; Wang, Zhisheng; Yan, Tianhai; Wang, Lizhi

    2015-01-01

    Vaccination through recombinant proteins against rumen methanogenesis provides a mitigation approach to reduce enteric methane (CH4) emissions in ruminants. The objective of present study was to evaluate the in vivo efficacy of a new vaccine candidate protein (EhaF) on methanogenesis and microbial population in the rumen of goats. We amplified the gene mru 1407 encoding protein EhaF using fresh rumen fluid samples of mature goats and successfully expressed recombinant protein (EhaF) in Escherichia coli Rosetta. This product was evaluated using 12 mature goats with half for control and other half injected with 400ug/goat the purified recombinant protein in day 1 and two subsequent booster immunizations in day 35 and 49. All measurements were undertaken from 63 to 68 days after the initial vaccination, with CH4 emissions determined using respiration calorimeter chambers. The results showed that the vaccination caused intensive immune responses in serum and saliva, although it had no significant effect on total enteric CH4 emissions and methanogen population in the rumen, when compared with the control goats. However, the vaccination altered the composition of rumen bacteria, especially the abundance of main phylum Firmicutes and genus Prevotella. The results indicate that protein EhaF might not be an effective vaccine to reduce enteric CH4 emissions but our vaccine have potential to influence the rumen ecosystem of goats. PMID:26445479

  6. Immunization against Rumen Methanogenesis by Vaccination with a New Recombinant Protein.

    PubMed

    Zhang, Litai; Huang, Xiaofeng; Xue, Bai; Peng, Quanhui; Wang, Zhisheng; Yan, Tianhai; Wang, Lizhi

    2015-01-01

    Vaccination through recombinant proteins against rumen methanogenesis provides a mitigation approach to reduce enteric methane (CH4) emissions in ruminants. The objective of present study was to evaluate the in vivo efficacy of a new vaccine candidate protein (EhaF) on methanogenesis and microbial population in the rumen of goats. We amplified the gene mru 1407 encoding protein EhaF using fresh rumen fluid samples of mature goats and successfully expressed recombinant protein (EhaF) in Escherichia coli Rosetta. This product was evaluated using 12 mature goats with half for control and other half injected with 400ug/goat the purified recombinant protein in day 1 and two subsequent booster immunizations in day 35 and 49. All measurements were undertaken from 63 to 68 days after the initial vaccination, with CH4 emissions determined using respiration calorimeter chambers. The results showed that the vaccination caused intensive immune responses in serum and saliva, although it had no significant effect on total enteric CH4 emissions and methanogen population in the rumen, when compared with the control goats. However, the vaccination altered the composition of rumen bacteria, especially the abundance of main phylum Firmicutes and genus Prevotella. The results indicate that protein EhaF might not be an effective vaccine to reduce enteric CH4 emissions but our vaccine have potential to influence the rumen ecosystem of goats.

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

    PubMed

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

    2015-08-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Pal, David; Jaffe, Peter

    2015-04-01

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

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

    SciTech Connect

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

    2000-02-05

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

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

    PubMed

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

    2010-11-01

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

  12. Distracted Driving

    MedlinePlus

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

  13. Kinetic model for methanogenesis of acetic acid in a multireactor system

    SciTech Connect

    Bhadra, A.; Mukhopadhyay, S.N.; Ghose, T.K.

    1984-01-01

    Bioconversion of acetic acid to methane by a crude culture of methanogens in a continuous multireactor system was investigateed. Culture of methanogens was drawn from an active cow-dung digester (12 days) and was grown in a semisynthetic medium (pH 6.3, 37/sup 0/C) with acetic acid as the sole carbon source. The solubilities of CO/sub 2/, HCO/sub 3//sup -/ and CO/sub 3//sup 2 -/ increased with the rise in pH and exercised considerable influence on the gas composition. Various mechanisms for methanogenesis of acetic acid based on the available pathways were considered. Experimental data were compared with these mechansims, the best fit was determined, and the corresponding rate expression was identified. This mechanism predicted that, of the total methane produced, 72% comes from acetic acid directly and 28% via the CO/sub 2/ reduction route.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    SciTech Connect

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

    1997-09-01

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

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

    NASA Astrophysics Data System (ADS)

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

    1997-09-01

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

  17. High-rate hydrogenotrophic methanogenesis for biogas upgrading: the role of anaerobic granules.

    PubMed

    Xu, Heng; Gong, Shufen; Sun, Yuanzi; Ma, Hailing; Zheng, Mingyue; Wang, Kaijun

    2015-01-01

    Hydrogenotrophic methanogenesis has been proved to be a feasible biological method for biogas upgrading. To improve its performance, the feasibility of typical anaerobic granules as the inoculum was investigated in both batch and continuous experiments. The results from batch experiments showed that glucose-acclimated granules seemed to perform better than granules acclimated to acidified products (AP, i.e. acetate, propionate and ethanol) in in situ biogas upgrading systems and a slightly higher H2 consumption rate (1.5 mmol H2 g VSS(-1) h(-1)) was obtained for glucose-acclimated granules. For AP-acclimated granules, the inhibition on anaerobic digestion and pH increase (up to 9.55±0.16) took place, and the upgrading performance was adversely affected. In contrast, better performance for AP-acclimated granules was observed in ex situ systems, possibly due to their higher hydrogenotrophic methanogenic activities (HMA). Moreover, when gas-liquid mass transfer limitations were alleviated, the upgrading performance was significantly improved (three-fold) for both glucose-acclimated and AP-acclimated granules. The HMA of anaerobic granules could be further enhanced to improve biogas upgrading performance via continuous cultivation with H2/CO2 as the sole substrate. During the three months' cultivation, secondary granulation and microbial population shift were observed, but anaerobic granules still remained intact and their HMA increased from 0.2 to 0.6 g COD g VSS(-1) d(-1). It indicated that the formation of hydrogenotrophic methanogenic granules, a new type of anaerobic granules specialized for high-rate hydrogenotrophic methanogenesis and biogas upgrading, might be possible. Conclusively, anaerobic granules showed great potential for biogas upgrading.

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

    PubMed

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

    2014-12-01

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

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

    PubMed Central

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

    2014-01-01

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

  20. Metabolic erosion primarily through mutation accumulation, and not tradeoffs, drives limited evolution of substrate specificity in Escherichia coli.

    PubMed

    Leiby, Nicholas; Marx, Christopher J

    2014-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  2. Mechanism for stabilizing mRNAs involved in methanol-dependent methanogenesis of cold-adaptive Methanosarcina mazei zm-15.

    PubMed

    Cao, Yi; Li, Jie; Jiang, Na; Dong, Xiuzhu

    2014-02-01

    Methylotrophic methanogenesis predominates at low temperatures in the cold Zoige wetland in Tibet. To elucidate the basis of cold-adapted methanogenesis in these habitats, Methanosarcina mazei zm-15 was isolated, and the molecular basis of its cold activity was studied. For this strain, aceticlastic methanogenesis was reduced 7.7-fold during growth at 15°C versus 30°C. Methanol-derived methanogenesis decreased only 3-fold under the same conditions, suggesting that it is more cold adaptive. Reverse transcription-quantitative PCR (RT-qPCR) detected <2-fold difference in the transcript abundances of mtaA1, mtaB1, and mtaC1, the methanol methyltransferase (Mta) genes, in 30°C versus 15°C culture, while ackA and pta mRNAs, encoding acetate kinase (Ack) and phosphotransacetylase (Pta) in aceticlastic methanogenesis, were 4.5- and 6.8-fold higher in 30°C culture than in 15°C culture. The in vivo half-lives of mtaA1 and mtaC1B1 mRNAs were similar in 30°C and 15°C cultures. However, the pta-ackA mRNA half-life was significantly reduced in 15°C culture compared to 30°C culture. Using circularized RNA RT-PCR, large 5' untranslated regions (UTRs) (270 nucleotides [nt] and 238 nt) were identified for mtaA1 and mtaC1B1 mRNAs, while only a 27-nt 5' UTR was present in the pta-ackA transcript. Removal of the 5' UTRs significantly reduced the in vitro half-lives of mtaA1 and mtaC1B1 mRNAs. Remarkably, fusion of the mtaA1 or mtaC1B1 5' UTRs to pta-ackA mRNA increased its in vitro half-life at both 30°C and 15°C. These results demonstrate that the large 5' UTRs significantly enhance the stability of the mRNAs involved in methanol-derived methanogenesis in the cold-adaptive M. mazei zm-15.

  3. Primarily Paper.

    ERIC Educational Resources Information Center

    Guhin, Paula

    2002-01-01

    Describes in detail an art assignment influenced by the book, "Collage Techniques: A Guide for Artists and Illustrators" (Gerald Broomer). Explains that students created mini-collages out of various types of paper, but focused on only three colors. (CMK)

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  5. Effect of dietary supplementation with resveratrol on nutrient digestibility, methanogenesis and ruminal microbial flora in sheep.

    PubMed

    Ma, T; Chen, D-D; Tu, Y; Zhang, N-F; Si, B-W; Deng, K-D; Diao, Q-Y

    2015-08-01

    Two experiments were conducted to evaluate the effect of resveratrol on methanogenesis and microbial flora in Dorper × thin-tailed Han cross-bred ewes. In experiment 1, ten ewes (67.2 ± 2.24 kg BW) were assigned to two dietary treatments, a basal diet and a basal diet supplemented with resveratrol (0.25 g/head·day), to investigate the effect of resveratrol on nutrient digestibility and nitrogen balance. In experiment 2, six ewes (64.0 ± 1.85 kg BW) with ruminal cannulae were assigned to the identical dietary treatments used in experiment 1 to investigate supplementary resveratrol on ruminal fermentation and microbial flora using qPCR. The results showed that supplementary resveratrol improved the digestibility of organic matter (OM; p < 0.001), nitrogen (N; p = 0.007), neutral detergent fibre (NDF; p < 0.001) and acid detergent fibre (ADF; p < 0.001). The excretion of faecal N was reduced (p = 0.007), whereas that of urinary N increased (p = 0.002), which led to an unchanged N retention (p = 0.157). Both CO2 and CH4 output scaled to digestible dry matter (DM) intake decreased from 602.5 to 518.7 (p = 0.039) and 68.2 to 56.6 (p < 0.001) respectively. Ruminal pH (p = 0.341), ammonia (p = 0.512) and total volatile fatty acid (VFA) (p = 0.249) were unaffected by resveratrol. The molar proportion of propionate increased from 13.1 to 17.5% (p < 0.001) while that of butyrate decreased from 11.0 to 9.55% (p < 0.001). The ratio of acetate to propionate (A/P) decreased from 5.44 to 3.96 (p < 0.001). Supplementary resveratrol increased ruminal population of Fibrobacter succinogenes, Ruminococcus albus and Butyrivibrio fibrisolvens (p < 0.001) while decreased protozoa and methanogens. In conclusion, dietary resveratrol inhibited methanogenesis without adversely affecting ruminal fermentation.

  6. Holokinetic drive: centromere drive in chromosomes without centromeres.

    PubMed

    Bureš, Petr; Zedek, František

    2014-08-01

    Similar to how the model of centromere drive explains the size and complexity of centromeres in monocentrics (organisms with localized centromeres), our model of holokinetic drive is consistent with the divergent evolution of chromosomal size and number in holocentrics (organisms with nonlocalized centromeres) exhibiting holokinetic meiosis (holokinetics). Holokinetic drive is proposed to facilitate chromosomal fission and/or repetitive DNA removal (or any segmental deletion) when smaller homologous chromosomes are preferentially inherited or chromosomal fusion and/or repetitive DNA proliferation (or any segmental duplication) when larger homologs are preferred. The hypothesis of holokinetic drive is supported primarily by the negative correlation between chromosome number and genome size that is documented in holokinetic lineages. The supporting value of two older cross-experiments on holokinetic structural heterozygotes (the rush Luzula elegans and butterflies of the genus Antheraea) that indicate the presence of size-preferential homolog transmission via female meiosis for holokinetic drive is discussed, along with the further potential consequences of holokinetic drive in comparison with centromere drive.

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

    SciTech Connect

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

    2014-11-26

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

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

    DOE PAGES

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

    2014-11-26

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

  9. Uncoupling of the Pathway of Methanogenesis in Northern Wetlands: Connection to Vegetation, and Implications for Variability and Predictability.

    NASA Astrophysics Data System (ADS)

    Hines, M. E.; Duddleston, K. N.; Chanton, J. P.

    2006-12-01

    Typical methanogenic decomposition pathways include near terminal carbon intermediates that turn over rapidly with small pool sizes. However, incubation and field experiments demonstrated that these organic intermediates accumulate in northern wetlands due to the lack of consumption by methanogenic bacteria. Acetate is the major organic end product of decomposition rather than CH4, and methanogenesis can be insignificant. The ratio of CO2:acetate:CH4 varied with vegetation type, and habitats dominated by non-vascular plants (Sphagnum) produced more acetate-C than CO2 or CH4. This ratio correlated well with stable C isotope alpha values used to delineate the path of CH4 formation. We suggest that methanogenesis in general is inhibited in oligotrophic wetlands, but that the conversion of acetate to CH4 is more sensitive, which increases the importance of the conversion of H2/CO2 to CH4. The relative importance of CH4 as an end product increased greatly in sites containing even small populations of Carex compared to sites inhabited only by Sphagnum, suggesting that subtle vegetation changes expected to occur during warming could lead to changes in the path of methanogenesis, increasing production. In addition, depth profiles revealed an active surficial (0-7 cm) C cycle that is sensitive to hydrology that may also greatly affect variability of CH4 formation. Acetate production represented a terminal process and was a sink for a large portion of metabolized C whose ultimate fate was aerobic oxidation to CO2. C destined for CH4 is thus bypassed to CO2 and does not contribute to atmospheric CH4. However, the connection and sensitivity of the pathway of methanogenesis to even small vegetation changes suggests that pathways can be mapped, they vary greatly over small distances, and they can change drastically with relatively small temperature increases.

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

    PubMed

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

    2015-02-01

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

  11. Bacterial sulfate reduction and methanogenesis in brackish, oligotrophic northern Baltic Sea sediments

    NASA Astrophysics Data System (ADS)

    Brüchert, Volker; Nguyen, Thang M.; Deutschmann, André; Böttcher, Michael E.; Ferdelman, Timothy G.

    2010-05-01

    Recent sediments of the northernmost Baltic Sea form underneath low-phosphate surface waters with year-round low primary production. Terrestrial organic matter from subarctic peatlands and tundra are important sources of organic matter in these sediments. These conditions make the northern Baltic an attractive Baltic analog of the Arctic shelf, because effects of changes in weathering patterns on land due to climate-related changes in temperature and runoff can be more easily studied in these sediments. Due to low production and salinities below 4 permil of northern Baltic Sea seawater, organic matter mineralization in these sediments has traditionally been thought to be dominated by aerobic respiration and suboxic diagenesis via bacterial denitrification, manganese, and iron reduction. Here we show with porewater water analyses of sulfate and methane as well as direct rate measurements of bacterial sulfate reduction and methanogenesis that these processes are more important for organic matter mineralization in these sediments than previously thought. Methane concentrations in porewaters reach saturation only few decimeters below the sediment surface and attest to the steep concentration profiles of sulfate driven by high rates of bacterial sulfate reduction. Anaerobic carbon mineralization and methane formation, and upward transport of methane to the sediment surface and water column are therefore significant components of Northern Baltic Sea sediment biogeochemistry.

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

    PubMed

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

    2013-03-01

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

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-09-01

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

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

    PubMed

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

    2016-09-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  18. Experimental evidence of an acetate transporter protein and characterization of acetate activation in aceticlastic methanogenesis of Methanosarcina mazei.

    PubMed

    Welte, Cornelia; Kröninger, Lena; Deppenmeier, Uwe

    2014-10-01

    Aceticlastic methanogens metabolize acetate to methane and carbon dioxide. The central metabolism and the electron transport chains of these organisms have already been investigated. However, no particular attention has been paid to the mechanism by which acetate enters the archaeal cell. In our study we investigated Methanosarcina mazei acetate kinase (Ack) and the acetate uptake reaction. At a concentration of 2 mM acetate, the Ack activity in cell extract of M. mazei was not limiting for the methane formation rate. Instead, the methanogenesis rate was controlled by the substrate concentration and increased 10-fold at 10 mM acetate. Subsequently, we analyzed the involvement of the putative acetate permease MM_0903 using a corresponding deletion mutant. At 2 mM acetate, only 25% of the wild-type methane formation rate was measured in the mutant. This indicated that the supply of acetate to Ack was limiting the rate of methane formation. Moreover, the mutant revealed an increased acetate kinase activity compared with the wild type. These results show for the first time that an acetate transporter is involved in aceticlastic methanogenesis and may be an important factor in the acetate threshold concentration for methanogenesis of Methanosarcina spp. PMID:25088360

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

    PubMed Central

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

    2016-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf; Klose, Melanie

    2011-03-01

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

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

    NASA Astrophysics Data System (ADS)

    Lazar, C.; Cody, G. D.

    2011-12-01

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

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

    PubMed

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

    2014-01-01

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

  4. Salinity constraints on subsurface archaeal diversity and methanogenesis in sedimentary rock rich in organic matter.

    PubMed

    Waldron, Patricia J; Petsch, Steven T; Martini, Anna M; Nüsslein, Klaus; Nüslein, Klaus

    2007-07-01

    The diversity of microorganisms active within sedimentary rocks provides important controls on the geochemistry of many subsurface environments. In particular, biodegradation of organic matter in sedimentary rocks contributes to the biogeochemical cycling of carbon and other elements and strongly impacts the recovery and quality of fossil fuel resources. In this study, archaeal diversity was investigated along a salinity gradient spanning 8 to 3,490 mM Cl(-) in a subsurface shale rich in CH(4) derived from biodegradation of sedimentary hydrocarbons. Shale pore waters collected from wells in the main CH(4)-producing zone lacked electron acceptors such as O(2), NO(3)(-), Fe(3+), or SO(4)(2-). Acetate was detected only in high-salinity waters, suggesting that acetoclastic methanogenesis is inhibited at Cl(-) concentrations above approximately 1,000 mM. Most-probable-number series revealed differences in methanogen substrate utilization (acetate, trimethylamine, or H(2)/CO(2)) associated with chlorinity. The greatest methane production in enrichment cultures was observed for incubations with salinity at or close to the native pore water salinity of the inoculum. Restriction fragment length polymorphism analyses of archaeal 16S rRNA genes from seven wells indicated that there were links between archaeal communities and pore water salinity. Archaeal clone libraries constructed from sequences from 16S rRNA genes isolated from two wells revealed phylotypes similar to a halophilic methylotrophic Methanohalophilus species and a hydrogenotrophic Methanoplanus species at high salinity and a single phylotype closely related to Methanocorpusculum bavaricum at low salinity. These results show that several distinct communities of methanogens persist in this subsurface, CH(4)-producing environment and that each community is adapted to particular conditions of salinity and preferential substrate use and each community induces distinct geochemical signatures in shale formation waters.

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    PubMed Central

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

    2015-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    PubMed

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

    2014-01-01

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

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

    PubMed Central

    Angel, Roey; Matthies, Diethart; Conrad, Ralf

    2011-01-01

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

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

    PubMed

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

    2015-02-01

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

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

    PubMed

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

    2015-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  13. Effects of coconut and fish oils on ruminal methanogenesis, fermentation, and abundance and diversity of microbial populations in vitro.

    PubMed

    Patra, A K; Yu, Z

    2013-03-01

    Coconut (CO) and fish (FO) oils were previously shown to inhibit rumen methanogenesis and biohydrogenation, which mitigates methane emission and helps improve beneficial fatty acids in meat and milk. This study aimed at investigating the comparative effects of CO and FO on the methanogenesis, fermentation, and microbial abundances and diversity in vitro rumen cultures containing different doses (0, 3.1, and 6.2 mL/L) of each oil and 400mg feed substrate using rumen fluid from lactating dairy cows as inocula. Increasing doses of CO and FO quadratically decreased concentrations of methane, but hydrogen concentrations were only increased quadratically by CO. Both oils linearly decreased dry matter and neutral detergent fiber digestibility of feeds but did not affect the concentration of total volatile fatty acids. However, CO reduced acetate percentage and acetate to propionate ratio and increased the percentages of propionate and butyrate to a greater extent than FO. Ammonia concentration was greater for CO than FO. As determined by quantitative real-time PCR, FO had greater inhibition to methanogens than CO, but the opposite was true for protozoal, Ruminococcus flavefaciens, and Fibrobacter succinogenes. Ruminococcus albus was not affected by either oil. Denaturing gradient gel electrophoresis (DGGE) profiles revealed that bacterial and archaeal community composition were changed differently by oil type. Based on Pareto-Lorenz evenness curve analysis of the DGGE profiles, CO noticeably changed the functional organization of archaea compared with FO. In conclusion, although both CO and FO decreased methane concentrations to a similar extent, the mode of reduction and the effect on abundances and diversity of archaeal and bacterial populations differed between the oils. Thus, the use of combination of CO and FO at a low dose may additively lower methanogenesis in the rumen while having little adverse effect on rumen fermentation. PMID:23332846

  14. Similar evolution in delta 13CH4 and model-predicted relative rate of aceticlastic methanogenesis during mesophilic methanization of municipal solid wastes.

    PubMed

    Vavilin, V A; Qu, X; Qu, X; Mazéas, L; Lemunier, M; Duquennoi, C; Mouchel, J M; He, P; Bouchez, T

    2009-01-01

    Similar evolution was obtained for the stable carbon isotope signatures delta (13)CH(4) and the model-predicted relative rate of aceticlastic methanogenesis during mesophilic methanization of municipal solid wastes. In batch incubations, the importance of aceticlastic and hydrogenotrophic methanogenesis changes in time. Initially, hydrogenotrophic methanogenesis dominated, but increasing population of Methanosarcina sp. enhances aceticlastic methanogenesis. Later, hydrogenotrophic methanogenesis intensified again. A mathematical model was developed to evaluate the relative contribution of hydrogenotrophic and aceticlastic pathways of methane generation during mesophilic batch anaerobic biodegradation of the French and the Chinese Municipal Solid Wastes (FMSW and CMSW). Taking into account molecular biology analysis reported earlier three groups of methanogens including strictly hydrogenotrophic methanogens, strictly aceticlastic methanogens (Methanosaeta sp.) and Methanosarcina sp., consuming both acetate and H(2)/H(2)CO(3) were considered in the model. The total organic and inorganic carbon concentrations, methane production volume, methane and carbon dioxide partial pressures values were used for the model calibration and validation. Methane isotopic composition (delta (13)CH(4)) evolution during the incubations was used to independently validate the model results. The model demonstrated that only the putrescible solid waste was totally converted to methane.

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

    PubMed Central

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

    1984-01-01

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

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

    PubMed

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

    2015-10-20

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

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

    PubMed

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

    2015-10-20

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

  18. Changes in Microbial Diversity, Methanogenesis and Fermentation Characteristics in the Rumen in Response to Medicinal Plant Extracts

    PubMed Central

    Kim, Eun Tae; Moon, Yea Hwang; Min, Kwan-Sik; Kim, Chang-Hyun; Kim, Sam Churl; Ahn, Seung Kyu; Lee, Sung Sill

    2013-01-01

    This study evaluated the in vitro effect of medicinal plant extracts on ruminal methanogenesis, four different groups of methanogens and ruminal fermentation characteristics. A fistulated Holstein cow was used as a donor of rumen fluid. Licorice and mugwort extracts (Glycyrrhiza uralensis and Artemisia capillaris, 0.5% and 1% of total substrate DM, respectively), previously used as folk remedies, were added to an in vitro fermentation incubated with buffered-rumen fluid. Total gas production in Glycyrrhiza uralensis extract treatment was not significantly different between treatments (p<0.05) while total gas production in the Artemisia capillaris extract treatment was lower than that of the control. Artemisia capillaris extract and Glycyrrhiza uralensis extract reduced CH4 emission by 14% (p<0.05) and 8% (p<0.05), respectively. Ciliate-associated methanogens population decreased by 18% in the medicinal plant extracts treatments. Medicinal plant extracts also affected the order Methanobacteriales community. Methanobacteriales diversity decreased by 35% in the Glycyrrhiza uralensis extract treatment and 30% in the Artemisia capillaris extract treatment. The order Methanomicrobiales population decreased by 50% in the 0.5% of Glycyrrhiza uralensis extract treatment. These findings demonstrate that medicinal plant extracts have the potential to inhibit in vitro ruminal methanogenesis. PMID:25049911

  19. Role of calcium oxide in sludge granulation and methanogenesis for the treatment of palm oil mill effluent using UASB reactor.

    PubMed

    Ahmad, Anwar; Ghufran, Rumana; Abd Wahid, Zularisam

    2011-12-30

    The granulation process in palm oil mill effluent using calcium oxide-cement kiln dust (CaO-CKD) provides an attractive and cost effective treatment option. In this study the efficiency of CaO-CKD at doses of 1.5-20 g/l was tested in batch experiments and found that 10 g of CaO/l caused the greatest degradation of VFA, butyrate and acetate. An upflow anaerobic sludge blanket (UASB) reactor was operated continuously at 35°C for 150 days to investigate the effect of CaO-CKD on sludge granulation and methanogenesis during start-up. The treatment of POME emphasized the influence of varying organic loading rates (OLR). Up to 94.9% of COD was removed when the reactor was fed with the 15.5-65.5 g-CODg/l at an OLR of 4.5-12.5 kg-COD/m(3)d, suggesting the feasibility of using CaO in an UASB process to treat POME. The ratio of volatile solids/total solids (VS/TS) and volatile fatty acids in the anaerobic sludge in the UASB reactor decreased significantly after long-term operation due to the precipitation of calcium carbonate in the granules. Granulation and methanogenesis decreased with an increase in the influent CaO-CKD concentration. PMID:22047724

  20. Safe driving for teens

    MedlinePlus

    Driving and teenagers; Teens and safe driving; Automobile safety - teenage drivers ... Make a Commitment to Safety Teens also need to commit to being safe and responsible drivers in order to improve the odds in their favor. Reckless driving ...

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  3. Extended Driving Impairs Nocturnal Driving Performances

    PubMed Central

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

    2008-01-01

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

  4. A possible role for bile acid in the control of methanogenesis and the accumulation of hydrogen gas in the human colon.

    PubMed

    Florin, T H; Jabbar, I A

    1994-01-01

    This study investigated a possible role for primary bile acid in the control of methanogenesis in the human colon. Production of hydrogen and methane was measured in anaerobic faecal cultures derived from faeces of six 'non-methanogenic' and three methanogenic healthy humans. Using a sensitive technique for gas measurement, methane was detected in all faecal cultures, including those from 'non-methanogenic' humans. Bile acid inhibited methanogenesis in a dose-response fashion in the in vitro 'non-methanogenic' and methanogenic faecal cultures. Inhibition was significant at bile acid concentrations > 0.05%. Methanogenesis correlated with methanogen (methanogenic bacteria) numbers. If this inhibition occurs in vivo, then it would explain much of the epidemiology of non-methanogenesis in humans. From an analysis of net hydrogen production by the faecal cultures, it is inferred that bile acid inhibits other hydrogen-consuming bacteria in addition to methanogens. These in vitro data suggest a major role for bile acid in the accumulation of hydrogen gas in the colon. Possible links between bile acid induced accumulation of gas and irritable bowel syndrome are discussed.

  5. Coaxial Redundant Drives

    NASA Technical Reports Server (NTRS)

    Brissette, R.

    1983-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-08-01

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

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

    PubMed

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

    2015-10-23

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

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

    PubMed

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

    2015-01-01

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

  10. Effect of fire residues (ash and char) on microbial activity, respiration and methanogenesis in three subtropical wetland soils

    NASA Astrophysics Data System (ADS)

    Medvedeff, C.; Hogue, B.; Inglett, P.

    2011-12-01

    Prescribed fire is a common restoration and maintenance technique in the southern United States. Prescribed burns coupled with frequent natural fires in South Florida can have devastating effects on ecosystem function. To determine the effect fire residues have on carbon biogeochemical cycling litter material was obtained from two restored and one native marl wetland in Everglades National Park and manipulated in a laboratory setting to produce ash and vegetation derived char. Based on vegetation biomass removal pre and post fire (insitu) appropriate aliquots of each fire residue was added to experimental microcosms as a soil amendment. Soil enzymes (β-glucosidase, cellobiohydrolase, phosphatase, bis-phosphate and leucine amino peptidase), aerobic and anaerobic respiration (CO2) potentials, extractable C and methanogenesis were measured over a 25 day period. Regardless of site C enzymes responded to both amendments within 5 days of addition. Similarly amended soil contained more extractable carbon in the reference and one of the restored sites. In the restored sites ash and char inhibited methanogenesis, had no effect on anaerobic CO2 potentials, but stimulated aerobic respiration after ten days. In contrast, within the first ten days phosphatase enzyme activity was lower in the ash treatment when compared to the control treatment and stimulation of aerobic respiration was observed in both treatment soils. After ten days ash stimulated methanogenic processing while suppressing anaerobic CO2 production suggesting methanogens in this ecosystem may be dependant on usable carbon substrates derived from aerobic microbial processing. This study illustrates the variable response of C parameters to complete and incomplete combusted materials produced from both prescribed and natural fires with particular importance to fire adapted ecosystems.

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

    PubMed

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

    2015-01-01

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

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

    PubMed

    Birgel, D; Meister, P; Lundberg, R; Horath, T D; Bontognali, T R R; Bahniuk, A M; de Rezende, C E; Vasconcelos, C; McKenzie, J A

    2015-05-01

    Holocene stromatolites characterized by unusually positive inorganic δ(13) CPDB values (i.e. up to +16‰) are present in Lagoa Salgada, a seasonally brackish to hypersaline lagoon near Rio de Janeiro (Brazil). Such positive values cannot be explained by phototrophic fixation of CO2 alone, and they suggest that methanogenesis was a dominating process during the growth of the stromatolites. Indeed, up to 5 mm methane was measured in the porewater. The archaeal membrane lipid archaeol showing δ(13) C values between -15 and 0‰ suggests that archaea are present and producing methane in the modern lagoon sediment. Moreover, (13) C-depleted hopanoids diplopterol and 3β-methylated C32 17β(H),21β(H)-hopanoic acid (both -40‰) are preserved in lagoon sediments and are most likely derived from aerobic methanotrophic bacteria thriving in the methane-enriched water column. Loss of isotopically light methane through the water column would explain the residual (13) C-enriched pool of dissolved inorganic carbon from where the carbonate constituting the stromatolites precipitated. The predominance of methanogenic archaea in the lagoon is most likely a result of sulphate limitation, suppressing the activity of sulphate-reducing bacteria under brackish conditions in a seasonally humid tropical environment. Indeed, sulphate-reduction activity is very low in the modern sediments. In absence of an efficient carbonate-inducing metabolic process, we propose that stromatolite formation in Lagoa Salgada was abiotically induced, while the (13) C-enriched organic and inorganic carbon pools are due to methanogenesis. Unusually, (13) C-enriched stromatolitic deposits also appear in the geological record of prolonged periods in the Palaeo- and Neoproterozoic. Lagoa Salgada represents a possible modern analogue to conditions that may have been widespread in the Proterozoic, at times when low sulphate concentrations in sea water allowed methanogens to prevail over sulphate

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

    PubMed Central

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

    2015-01-01

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

  14. Solar array drive system

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  15. 12 CFR 225.127 - Investment in corporations or projects designed primarily to promote community welfare.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Nation's social problems. Although the interpretation primarily focuses on low- and moderate-income... remedying our social ills. Section 225.25(b)(6) is intended to provide an opportunity for them to assume... or medium-sized locally-controlled businesses in low-income urban or other economically...

  16. 12 CFR 225.127 - Investment in corporations or projects designed primarily to promote community welfare.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... social problems. Although the interpretation primarily focuses on low- and moderate-income housing, it is... social ills. Section 225.25(b)(6) is intended to provide an opportunity for them to assume such a role... groups (for example, minority equity investments, on a temporary basis, in small or medium-sized...

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

    Code of Federal Regulations, 2011 CFR

    2011-07-01

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

  18. Enthusiasm Is Not Enough: Beginning Secondary Science Teachers in Primarily Hispanic Settings.

    ERIC Educational Resources Information Center

    Luft, Julie A.; Roehrig, Gillian

    2005-01-01

    This study explores the practices of three beginning secondary science teachers. The teachers were in their first year, worked with primarily Hispanic students in rural and urban schools, held undergraduate degrees in science, participated in postbaccalaureate certification programs of varying lengths, and had different cultural backgrounds from…

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

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 3 2010-07-01 2010-07-01 false âPrimarily employedâ in agriculture. 780.607 Section 780.607 Labor Regulations Relating to Labor (Continued) WAGE AND HOUR DIVISION, DEPARTMENT OF LABOR STATEMENTS OF GENERAL POLICY OR INTERPRETATION NOT DIRECTLY RELATED TO REGULATIONS EXEMPTIONS APPLICABLE TO AGRICULTURE, PROCESSING OF...

  20. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

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

  1. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

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

  2. 29 CFR 780.607 - “Primarily employed” in agriculture.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

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

  3. 12 CFR 225.127 - Investment in corporations or projects designed primarily to promote community welfare.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Nation's social problems. Although the interpretation primarily focuses on low- and moderate-income... remedying our social ills. Section 225.25(b)(6) is intended to provide an opportunity for them to assume... or medium-sized locally-controlled businesses in low-income urban or other economically...

  4. Propulsion and control propellers with thruster nozzles primarily for aircraft applications

    NASA Technical Reports Server (NTRS)

    Pabst, W.

    1986-01-01

    A propulsion and control propeller with thruster nozzles, primarily for aircraft application is described. Adjustability of rotor blades at the hub and pressurized gas expulsion combined with an air propeller increase power. Both characteristics are combined in one simple device, and, furthermore, incorporate overall aircraft control so that mechanisms which govern lateral and horizontal movement become superfluous.

  5. 12 CFR 225.127 - Investment in corporations or projects designed primarily to promote community welfare.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... social problems. Although the interpretation primarily focuses on low- and moderate-income housing, it is... social ills. Section 225.25(b)(6) is intended to provide an opportunity for them to assume such a role... groups (for example, minority equity investments, on a temporary basis, in small or medium-sized...

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

    ERIC Educational Resources Information Center

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

    2014-01-01

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

  7. Examining the Effects of Introducing Online Access to ACS Journals at Primarily Undergraduate Institutions

    ERIC Educational Resources Information Center

    Landolt, R. G.

    2007-01-01

    In collaboration with the Publications Division of the American Chemical Society (ACS), students and faculty at 24 primarily undergraduate institutions were provided online access to ACS primary research journals for a period of 18 months, and a group of eight schools were granted access to use the archives of ACS journals for a year. Resources…

  8. Driving and neurodegenerative diseases.

    PubMed

    Uc, Ergun Y; Rizzo, Matthew

    2008-09-01

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

  9. Dementia and driving

    MedlinePlus

    ... has dementia , deciding when they can no longer drive may be difficult. They may react in different ... that the person may not be able to drive safely, such as: Forgetting recent events Mood swings ...

  10. Gear bearing drive

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  11. Sequential Dependencies in Driving

    ERIC Educational Resources Information Center

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

    2012-01-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  13. Electric versus hydraulic drives

    SciTech Connect

    Not Available

    1983-01-01

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

  14. Potentially Inappropriate Prescribing of Primarily Renally Cleared Medications for Older Veterans Affairs Nursing Home Patients

    PubMed Central

    Hanlon, Joseph T.; Wang, Xiaoqiang; Handler, Steven M.; Weisbord, Steven; Pugh, Mary Jo; Semla, Todd; Stone, Roslyn A.; Aspinall, Sherrie L.

    2010-01-01

    Background Inappropriate prescribing of primarily renally cleared medications in older patients with kidney disease can lead to adverse outcomes. Objectives To estimate the prevalence of potentially inappropriate prescribing of 21 primarily renally cleared medications based on 2 separate estimates of renal function and to identify factors associated with this form of suboptimal prescribing in older VA nursing home (NH) patients. Design Longitudinal study Participants Participants were 1304 patients, aged 65 years or older, admitted between January 1, 2004, and June 30, 2005, for 90 days or more to 1 of 133 VA NHs. Main Measures Potentially inappropriate prescribing of primarily renally cleared medications determined by estimating creatinine clearance using the Cock-croft Gault (CG) and Modification of Diet in Renal Disease (MDRD) equations and applying explicit guidelines for contraindicated medications and dosing. Key Results The median estimated creatinine clearance via CG was 67 mL/min, whereas it was 80 mL/min/1.73m2 with the MDRD. Overall, 11.89% patients via CG and only 5.98% via MDRD had evidence of potentially inappropriate prescribing of at least 1 renally cleared medication. The most commonly involved medications were ranitidine, glyburide, gabapentin, and nitrofurantoin. Factors associated with potentially inappropriate prescribing as per the CG were age older than 85 (adjusted odds ratio [AOR] 4.24, 95% confidence interval [CI] 2.42–7.43), obesity (AOR 0.26, 95% CI 0.14–0.50) and having multiple comorbidities (AOR 1.09 for each unit increase in the Charlson comorbidity index, 95% CI 1.01–1.19). Conclusions Potentially inappropriate prescribing of renally cleared medications is common in older VA NH patients. Intervention studies to improve the prescribing of primarily renally cleared medications in nursing homes are needed. PMID:21450179

  15. Primarily chronic progressive and relapsing/remitting multiple sclerosis: two immunogenetically distinct disease entities.

    PubMed Central

    Olerup, O; Hillert, J; Fredrikson, S; Olsson, T; Kam-Hansen, S; Möller, E; Carlsson, B; Wallin, J

    1989-01-01

    HLA class II gene polymorphism was investigated in 100 patients with clinically definite multiple sclerosis (MS) by restriction fragment length polymorphism analysis of Taq I-digested DNA using DRB, DQA, and DQB cDNA probes. Twenty-six patients had primarily chronic progressive MS and 74 had relapsing/remitting MS. The latter group included patients with a secondary progressive evolution of symptoms. Both clinical forms of MS were found to be associated with the DRw15,DQw6 haplotype. In addition, primarily chronic progressive MS was positively associated with the DQB1 restriction fragment pattern seen in DR4,DQw8, DR7,DQw9, and DRw8, DQw4 haplotypes, as well as negatively associated with the Taq I DQB1 allelic pattern corresponding to the serological specificity DQw7. Relapsing/remitting MS was positively associated with the DQB1 allelic pattern observed in the DRw17,DQw2 haplotype. These three DQB1 alleles are in strong negative linkage disequilibria with DRw15. The two susceptibility markers of each clinical form of MS act additively in determining the genetic susceptibility, as the relative risks for individuals carrying both markers roughly equal the sum of respective risks. Different alleles of the DQB1 locus defined by restriction fragment length polymorphisms contribute to susceptibility and resistance to primarily chronic progressive MS as well as to susceptibility to relapsing/remitting MS. The observed immunogenetic heterogeneity between the different clinical forms of MS favors the hypothesis that primarily chronic progressive MS and relapsing/remitting MS are two distinct disease entities. Images PMID:2571150

  16. Environmental changes affect the assembly of soil bacterial community primarily by mediating stochastic processes.

    PubMed

    Zhang, Ximei; Johnston, Eric R; Liu, Wei; Li, Linghao; Han, Xingguo

    2016-01-01

    Both 'species fitness difference'-based deterministic processes, such as competitive exclusion and environmental filtering, and 'species fitness difference'-independent stochastic processes, such as birth/death and dispersal/colonization, can influence the assembly of soil microbial communities. However, how both types of processes are mediated by anthropogenic environmental changes has rarely been explored. Here we report a novel and general pattern that almost all anthropogenic environmental changes that took place in a grassland ecosystem affected soil bacterial community assembly primarily through promoting or restraining stochastic processes. We performed four experiments mimicking 16 types of environmental changes and separated the compositional variation of soil bacterial communities caused by each environmental change into deterministic and stochastic components, with a recently developed method. Briefly, because the difference between control and treatment communities is primarily caused by deterministic processes, the deterministic change was quantified as (mean compositional variation between treatment and control) - (mean compositional variation within control). The difference among replicate treatment communities is primarily caused by stochastic processes, so the stochastic change was estimated as (mean compositional variation within treatment) - (mean compositional variation within control). The absolute of the stochastic change was greater than that of the deterministic change across almost all environmental changes, which was robust for both taxonomic and functional-based criterion. Although the deterministic change may become more important as environmental changes last longer, our findings showed that changes usually occurred through mediating stochastic processes over 5 years, challenging the traditional determinism-dominated view.

  17. Drill drive mechanism

    DOEpatents

    Dressel, Michael O.

    1979-01-01

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

  18. Hydrolysis, acidification and methanogenesis during low-temperature anaerobic digestion of dilute dairy wastewater in an inverted fluidised bioreactor.

    PubMed

    Bialek, Katarzyna; Cysneiros, Denise; O'Flaherty, Vincent

    2014-10-01

    The application of low-temperature (10 °C) anaerobic digestion (LtAD) for the treatment of complex dairy-based wastewater in an inverted fluidised bed (IFB) reactor was investigated. Inadequate mixing intensity provoked poor hydrolysis of the substrate (mostly protein), which resulted in low chemical oxygen demand (COD) removal efficiency throughout the trial, averaging ~69 % at the best operational period. Overgrowth of the attached biomass to the support particles (Extendospheres) induced bed stratification by provoking agglutination of the particles and supporting their washout by sedimentation, which contributed to unstable bioprocess performance at the organic loading rates (OLRs) between 0.5 and 5 kg COD m(-3) day(-1). An applied OLR above 2 kg COD m(-3) day(-1) additionally promoted acidification and strongly influenced the microbial composition and dynamics. Hydrogenotrophic methanogens appeared to be the mostly affected group by the Extendospheres particle washout as a decrease in their abundance was observed by quantitative PCR analysis towards the end of the trial, although the specific methanogenic activity and maximum substrate utilisation rate on H2/CO2 indicated high metabolic activity and preference towards hydrogenotrophic methanogenesis of the reactor biomass at this stage. The bacterial community in the bioreactor monitored via denaturing gradient gel electrophoresis (DGGE) also suggested an influence of OLR stress on bacterial community structure and population dynamics. The data presented in this work can provide useful information in future optimisation of fluidised reactors intended for digestion of complex industrial wastewaters during LtAD. PMID:24946864

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

    PubMed

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

    2016-03-15

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

  20. Hydrolysis, acidification and methanogenesis during low-temperature anaerobic digestion of dilute dairy wastewater in an inverted fluidised bioreactor.

    PubMed

    Bialek, Katarzyna; Cysneiros, Denise; O'Flaherty, Vincent

    2014-10-01

    The application of low-temperature (10 °C) anaerobic digestion (LtAD) for the treatment of complex dairy-based wastewater in an inverted fluidised bed (IFB) reactor was investigated. Inadequate mixing intensity provoked poor hydrolysis of the substrate (mostly protein), which resulted in low chemical oxygen demand (COD) removal efficiency throughout the trial, averaging ~69 % at the best operational period. Overgrowth of the attached biomass to the support particles (Extendospheres) induced bed stratification by provoking agglutination of the particles and supporting their washout by sedimentation, which contributed to unstable bioprocess performance at the organic loading rates (OLRs) between 0.5 and 5 kg COD m(-3) day(-1). An applied OLR above 2 kg COD m(-3) day(-1) additionally promoted acidification and strongly influenced the microbial composition and dynamics. Hydrogenotrophic methanogens appeared to be the mostly affected group by the Extendospheres particle washout as a decrease in their abundance was observed by quantitative PCR analysis towards the end of the trial, although the specific methanogenic activity and maximum substrate utilisation rate on H2/CO2 indicated high metabolic activity and preference towards hydrogenotrophic methanogenesis of the reactor biomass at this stage. The bacterial community in the bioreactor monitored via denaturing gradient gel electrophoresis (DGGE) also suggested an influence of OLR stress on bacterial community structure and population dynamics. The data presented in this work can provide useful information in future optimisation of fluidised reactors intended for digestion of complex industrial wastewaters during LtAD.

  1. Inhibition of methanogenesis in salt marsh sediments and whole-cell suspensions of methanogenic bacteria by nitrogen oxides.

    PubMed Central

    Balderston, W L; Payne, W J

    1976-01-01

    Hydrogen-dependent evolution of methane from salt marsh sediments and whole-cell suspensions of Methanobacterium thermoautotrophicum and Methanobacterium fornicicum ceased or decreased after the introduction of nitrate, nitrite, nitric oxide, or nitrous oxide. Sulfite had a similar effect on methanogenesis in the whole-cell suspensions. In salt marsh sediments, nitrous oxide was the strongest inhibitor, followed by nitric oxide, nitrite, and nitrate in decreasing order of inhibition. In whole-cell suspensions, nitric oxide was the strongest inhibitor, followed by nitrous oxide, nitrite, and nitrate. Consideration of the results from experiments using an indicator of oxidation potential, along with the reversed order of effectiveness of the nitrogen oxides in relation to their degree of reduction ,suggests that the inhibitory effect observed was not due to a redox change. Evidence is also presented that suggests that the decrease in the rate of methane production in the presence of oxides of nitrogen was not attributable to competition for methane-producing substrates. PMID:970945

  2. Evidence for syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis in the high-temperature petroleum reservoir of Yabase oil field (Japan).

    PubMed

    Mayumi, Daisuke; Mochimaru, Hanako; Yoshioka, Hideyoshi; Sakata, Susumu; Maeda, Haruo; Miyagawa, Yoshihiro; Ikarashi, Masayuki; Takeuchi, Mio; Kamagata, Yoichi

    2011-08-01

    The methanogenic communities and pathways in a high-temperature petroleum reservoir were investigated through incubations of the production water and crude oil, combined with radiotracer experiments and molecular biological analyses. The incubations were conducted without any substrate amendment and under high-temperature and pressurized conditions that mimicked the in situ environment (55°C, 5 MPa). Changes in methane and acetate concentrations during the incubations indicated stoichiometric production of methane from acetate. Rates of hydrogenotrophic methanogenesis measured using [(14)C]-bicarbonate were 42-68 times those of acetoclastic methanogenesis measured using [2-(14) C]-acetate, implying the dominance of methane production by syntrophic acetate oxidation coupled to hydrogenotrophic methanogenesis in the environment. 16S rRNA gene sequence analyses of the incubated production water showed bacterial communities dominated by the genus Thermacetogenium, known as a thermophilic syntrophic acetate-oxidizing bacterium, and archaeal communities dominated by thermophilic hydrogenotrophic methanogens belonging to the genus Methanothermobacter. Furthermore, group-specific real-time PCR assays revealed that 16S rRNA gene copy numbers of the hydrogenotrophic methanogens affiliated with the order Methanobacteriales were almost identical to those of archaeal 16S rRNA genes. This study demonstrates that syntrophic acetate oxidation is the main methanogenic pathway in a high-temperature petroleum reservoir.

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

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

  6. Bilateral Krukenberg Tumours Diagnosed Primarily by Transabdominal Sonography- A Case Report

    PubMed Central

    Padala, Krishna Prasanthi; Mahesh; Gowda, Gautham; Pailoor, Aruna

    2015-01-01

    Krukenberg tumour, also known as carcinoma mucocellulare, is a metastatic adenocarcinoma of ovaries from different primary tumour sites. Gastric carcinoma is most common primary tumour responsible for approximately 50% of Krukenberg tumours. Discrimination between primary ovarian cancer and metastatic tumours in the ovary is important, because their management is different. Here we present a case of female suffering from gastric carcinoma with bilateral Krukenberg tumours, diagnosed primarily by transabdominal sonography. The patient was referred to higher centre for further treatment and followed up. PMID:26816967

  7. Lectures on magnetohydrodynamical drives

    NASA Astrophysics Data System (ADS)

    Loigom, Villem

    The paper deals with nonconventional types of electrical machines and drives - magnetohydrodynamical (MHD) machines and drives. In cardinal it is based on the research conducted with participation of the author in Tallinn Technical University at the Institute of Electrical Drives and Power Electronics, where the use of magnetohydrodynamical motors and drives in the metallurgical and casting industries have been studied for a long time. Major research interests include the qualities and applications of the induction MHD-drives for set in the motion (pumping, turning, dosing, mixing, etc.) non-ferrous molten metals like Al, Mg, Sn, Pb, Na, K, and their alloys. The first part of the paper describes induction MHD motors and their electrohydraulical qualities. In the second part energy conversion problems are described. Also, on the basis of the analogy between electromechanical and electrohydraulical phenomenas, static and dynamic qualities of MHD drives with induction MHD machines are discussed.

  8. Superluminal warp drive

    NASA Astrophysics Data System (ADS)

    González-Díaz, Pedro F.

    2007-09-01

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

  9. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

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

  10. 49 CFR 37.171 - Equivalency requirement for demand responsive service operated by private entities not primarily...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

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

  11. Diabetes and driving.

    PubMed

    Inkster, B; Frier, B M

    2013-09-01

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

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

    PubMed Central

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

    2014-01-01

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

  13. Reading Text While Driving

    PubMed Central

    Horrey, William J.; Hoffman, Joshua D.

    2015-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  15. Ocular disease and driving.

    PubMed

    Wood, Joanne M; Black, Alex A

    2016-09-01

    As the driving population ages, the number of drivers with visual impairment resulting from ocular disease will increase given the age-related prevalence of ocular disease. The increase in visual impairment in the driving population has a number of implications for driving outcomes. This review summarises current research regarding the impact of common ocular diseases on driving ability and safety, with particular focus on cataract, glaucoma, age-related macular degeneration, hemianopia and diabetic retinopathy. The evidence considered includes self-reported driving outcomes, driving performance (on-road and simulator-based) and various motor vehicle crash indices. Collectively, this review demonstrates that driving ability and safety are negatively affected by ocular disease; however, further research is needed in this area. Older drivers with ocular disease need to be aware of the negative consequences of their ocular condition and in the case where treatment options are available, encouraged to seek these earlier for optimum driving safety and quality of life benefits. PMID:27156178

  16. Electric vehicles: Driving range

    NASA Astrophysics Data System (ADS)

    Kempton, Willett

    2016-09-01

    For uptake of electric vehicles to increase, consumers' driving-range needs must be fulfilled. Analysis of the driving patterns of personal vehicles in the US now shows that today's electric vehicles can meet all travel needs on almost 90% of days from a single overnight charge.

  17. Piezoelectric drive circuit

    DOEpatents

    Treu, C.A. Jr.

    1999-08-31

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

  18. Piezoelectric drive circuit

    DOEpatents

    Treu, Jr., Charles A.

    1999-08-31

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

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

    PubMed Central

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

    2016-01-01

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

  20. Indolent non-Hodgkin lymphoma primarily involving the hard palate: outcome following radiotherapy.

    PubMed

    Milgrom, Sarah A; Yahalom, Joachim

    2013-06-01

    The aim of this study was to report the clinical and pathological characteristics, treatment strategies and outcome in patients with indolent non-Hodgkin lymphoma (NHL) primarily involving the hard palate. Nine consecutive patients with indolent NHL of the hard palate were identified. The palate was a site of initial disease for six patients (four stage IAE and two stage IIIAE) and of relapse for three. There were four cases of grade 1-2 follicular lymphoma (FL), two of mantle cell lymphoma (MCL) and three of marginal zone lymphoma (MZL). All nine patients received involved site radiation therapy (RT) alone. There was no grade ≥ 3 toxicity. At a median follow-up of 55 months, 5-year freedom from local progression was 100%, disease-free survival was 38% and overall survival was 80%. In conclusion, involved site RT is well tolerated and provides excellent local control in the management of indolent lymphoma of the hard palate. PMID:23083063

  1. Consensus Guidelines for Oral Dosing of Primarily Renally Cleared Medications in Older Adults

    PubMed Central

    Hanlon, Joseph T.; Aspinall, Sherrie L.; Semla, Todd P.; Weisbord, Steven D.; Fried, Linda F.; Good, C. Bernie; Fine, Michael J.; Stone, Roslyn A.; Pugh, Mary Jo V.; Rossi, Michelle I.; Handler, Steven M.

    2008-01-01

    Objectives To establish consensus oral dosing guidelines for primarily renally cleared medications prescribed for older adults. Design Two-round modified Delphi Survey. Participants Expert panel of 11 geriatric clinical pharmacists. Measurements After a comprehensive literature search and review by the investigative group of 6 physicians (2 from general internal medicine, 2 nephrologists, 2 geriatricians), 45 dosing recommendations for 30 medications at various levels of renal function were created. The expert panel rated their agreement with each of these 45 dosing recommendations using a 5-point Likert scale (1= strongly disagree to 5=strongly agree). Recommendation-specific means and 95% confidence intervals were estimated. Consensus was defined as a lower 95% confidence limit of >4.0 for the recommendation –specific mean score. Results The response rate was 81.8% (9/11) for the first round. All respondents that completed the first round also completed the second round. The expert panel reached consensus on 26 recommendations involving 18 (60%) medications. For 10 medications (chlorpropamide, colchicine, cotrimoxazole, glyburide, meperidine, nitrofurantoin, probenecid, propoxyphene, spironolactone, and triamterene), the consensus recommendation was not to use the medication in older adults below a specified level of renal function (e.g., creatinine clearance < 30 ml/min). For the remaining 8 medications (acyclovir, amantadine, ciprofloxacin, gabapentin, memantine, ranitidine, rimantadine, and valacyclovir), specific recommendations for dose reduction or interval extension were made. Conclusion An expert panel of geriatric clinical pharmacists was able to reach consensus agreement on a number of oral medications that are primarily renally cleared. PMID:19170784

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

    PubMed Central

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

    2016-01-01

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

  3. Design of traction drives

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

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

  4. Efficient transfection of DNA into primarily cultured rat sertoli cells by electroporation.

    PubMed

    Li, Fuping; Yamaguchi, Kohei; Okada, Keisuke; Matsushita, Kei; Enatsu, Noritoshi; Chiba, Koji; Yue, Huanxun; Fujisawa, Masato

    2013-03-01

    The expression of exogenous DNA in Sertoli cells is essential for studying its functional genomics, pathway analysis, and medical applications. Electroporation is a valuable tool for nucleic acid delivery, even in primarily cultured cells, which are considered difficult to transfect. In this study, we developed an optimized protocol for electroporation-based transfection of Sertoli cells and compared its efficiency with conventional lipofection. Sertoli cells were transfected with pCMV-GFP plasmid by square-wave electroporation under different conditions. After transfection of plasmid into Sertoli cells, enhanced green fluorescent protein (EGFP) expression could be easily detected by fluorescent microscopy, and cell survival was evaluated by dye exclusion assay using Trypan blue. In terms of both cell survival and the percentage expressing EGFP, 250 V was determined to produce the greatest number of transiently transfected cells. Keeping the voltage constant (250 V), relatively high cell survival (76.5% ± 3.4%) and transfection efficiency (30.6% ± 5.6%) were observed with a pulse length of 20 μm. The number of pulses significantly affected cell survival and EGFP expression (P < 0.001). Cell survival clearly decreased following one to three pulses, from 83.9% ± 6.1% to 3.2% ± 1.1%, with EGFP expression increasing from 41.8% ± 9.4% to 66.7% ± 5.2%. The yield of positive cells increased with increasing concentration of plasmid DNA (range, 10-50 μg/ml), from 14.0% ± 2.8% to 35.0% ± 6.3%, but cell viability steadily decreased following 20 μg/ml plasmid DNA, from 73.1% ± 4.9% to 57.0% ± 6.6%. Compared with two popular cationic lipid transfection methods, the transfection efficiency of electroporation (21.5% ± 5.7%) was significantly higher than those of Lipofectamine 2000 (2.9% ± 1.0%) and Effectene (1.9% ± 0.8%) in this experiment (P < 0.001). We describe the process of optimizing electroporation conditions, and the successful electroporation of plasmid

  5. The development and characterization of a primarily mineral calcium phosphate - poly(epsilon-caprolactone) biocomposite

    NASA Astrophysics Data System (ADS)

    Dunkley, Ian Robert

    Orthopaedic reconstruction often involves the surgical introduction of structural implants that provide for rigid fixation, skeletal stabilization, and bone integration. The high stresses incurred by these implanted devices have historically limited material choices to metallic and select polymeric formulations. While mechanical requirements are achieved, these non-degradable materials do not participate actively in the remodeling of the skeleton and present the possibility of long-term failure or rejection. This is particularly relevant in cervical fusion, an orthopaedic procedure to treat damaged, degenerative or diseased intervertebral discs. A significant improvement on the available synthetic bone replacement/regeneration options for implants to treat these conditions in the cervical spine may be achieved with the development of primarily mineral biocomposites comprised of a bioactive ceramic matrix reinforced with a biodegradable polymer. Such a biocomposite may be engineered to possess the clinically required mechanical properties of a particular application, while maintaining the ability to be remodeled completely by the body. A biocomposite of Si-doped calcium phosphate (Si-CaP) and poly(epsilon-caprolactone) (PCL) was developed for application as such a synthetic bone material for potential use as a fusion device in the cervical spine. In this thesis, a method by which high mineral content Si-CaP/PCL biocomposites with interpenetrating matrices of mineral and polymer phases may be prepared will be demonstrated, in addition to the effects of the various preparation parameters on the biocomposite density, porosity and mechanical properties. This new technique by which dense, primarily ceramic Si-CaP/PCL biocomposites were prepared, allowed for the incorporation of mineral contents ranging between 45-97vol%. Polymer infiltration, accomplished solely by passive capillary uptake over several days, was found to be capable of fully infiltrating the microporosity

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

    PubMed Central

    Patra, Amlan K.; Yu, Zhongtang

    2015-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  8. The Test Drive

    NASA Technical Reports Server (NTRS)

    2004-01-01

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

  9. Vision and Driving

    PubMed Central

    Owsley, Cynthia; McGwin, Gerald

    2010-01-01

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

  10. Drive System Research

    NASA Technical Reports Server (NTRS)

    Handschuh, Robert F.

    2007-01-01

    An overview of the NASA Glenn Research Center Drive Systems Research will be presented. The primary purpose of this research is to improve performance, reliability, and integrity of aerospace drive systems and space mechanisms. The research is conducted through a combination of in-house, academia, and through contractors. Research is conducted through computer code development and validated through component and system testing. The drive system activity currently has four major thrust areas including: thermal behavior of high speed gearing, health and usage monitoring, advanced components, and space mechanisms.

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

    PubMed Central

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

    2014-01-01

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

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

    SciTech Connect

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

    2006-03-24

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

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

    NASA Astrophysics Data System (ADS)

    Lopez, Ramon E.

    2016-05-01

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

  14. Spontaneous reports of primarily suspected herbal hepatotoxicity by Pelargonium sidoides: was causality adequately ascertained?

    PubMed

    Teschke, Rolf; Frenzel, Christian; Schulze, Johannes; Eickhoff, Axel

    2012-06-01

    Spontaneous reports of primarily assumed hepatotoxicity in connection with the use of Pelargonium sidoides (PS) have been interpreted by the Drug Commission of the German Medical Association (DCGMA) as showing some hepatotoxic potential of PS used to treat common cold and other respiratory tract infections. Causality for PS was assessed using the liver specific, structured, quantitative, and updated scale of the Council for International Organizations of Medical Sciences (CIOMS). In none of the 15 cases was there a highly probable or probable causality for PS. Analysis revealed confounding factors such as numerous final diagnoses unrelated to PS and poor data quality in virtually all cases. In only a minority of the cases were data provided to consider even common other diseases of the liver. For instance, biliary tract imaging data were available in only 3 patients; data to exclude virus infections by hepatitis A-C were provided in 4 cases and by CMV and EBV in 1 case, whereas HSV and VZV virus infections remained unconsidered. Thus, convincing evidence is lacking that PS was a potential hepatotoxin in the analyzed cases.

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

    PubMed

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

    2011-04-14

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

  16. Audiovisual contrast enhancement is articulated primarily via the M-pathway.

    PubMed

    Jaekl, Philip M; Soto-Faraco, Salvador

    2010-12-17

    Although it has been previously reported that audiovisual integration can modulate performance on some visual tasks, multisensory interactions have not been explicitly assessed in the context of different visual processing pathways. In the present study, we test auditory influences on visual processing employing a psychophysical paradigm that reveals distinct spatial contrast signatures of magnocellular and parvocellular visual pathways. We found that contrast thresholds are reduced when noninformative sounds are presented with transient, low-frequency Gabor patch stimuli and thus favor the M-system. In contrast, visual thresholds are unaffected by concurrent sounds when detection is primarily attributed to P-pathway processing. These results demonstrate that the visual detection enhancement resulting from multisensory integration is mainly articulated by the magnocellular system, which is most sensitive at low spatial frequencies. Such enhancement may subserve stimulus-driven processes including the orientation of spatial attention and fast, automatic ocular and motor responses. This dissociation helps explain discrepancies between the results of previous studies investigating visual enhancement by sounds.

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

    PubMed

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

    2015-09-01

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

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

    PubMed

    Pansarin, E R; Pansarin, L M

    2014-11-01

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

  19. Visual processing of informative multipoint correlations arises primarily in V2.

    PubMed

    Yu, Yunguo; Schmid, Anita M; Victor, Jonathan D

    2015-04-27

    Using the visual system as a model, we recently showed that the efficient coding principle accounted for the allocation of computational resources in central sensory processing: when sampling an image is the main limitation, resources are devoted to compute the statistical features that are the most variable, and therefore the most informative (eLife 2014;3:e03722. DOI: 10.7554/eLife.03722 Hermundstad et al., 2014). Building on these results, we use single-unit recordings in the macaque monkey to determine where these computations--sensitivity to specific multipoint correlations--occur. We find that these computations take place in visual area V2, primarily in its supragranular layers. The demonstration that V2 neurons are sensitive to the multipoint correlations that are informative about natural images provides a common computational underpinning for diverse but well-recognized aspects of neural processing in V2, including its sensitivity to corners, junctions, illusory contours, figure/ground, and 'naturalness.'

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

    PubMed Central

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

    2015-01-01

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

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

    SciTech Connect

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

    2011-12-31

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

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

    PubMed

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

    2015-09-01

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

  3. Tribolium castaneum defensins are primarily active against Gram-positive bacteria.

    PubMed

    Tonk, Miray; Knorr, Eileen; Cabezas-Cruz, Alejandro; Valdés, James J; Kollewe, Christian; Vilcinskas, Andreas

    2015-11-01

    The red flour beetle Tribolium castaneum is a destructive insect pest of stored food and feed products, and a model organism for development, evolutionary biology and immunity. The insect innate immune system includes antimicrobial peptides (AMPs) with a wide spectrum of targets including viruses, bacteria, fungi and parasites. Defensins are an evolutionarily-conserved class of AMPs and a potential new source of antimicrobial agents. In this context, we report the antimicrobial activity, phylogenetic and structural properties of three T. castaneum defensins (Def1, Def2 and Def3) and their relevance in the immunity of T. castaneum against bacterial pathogens. All three recombinant defensins showed bactericidal activity against Micrococcus luteus and Bacillus thuringiensis serovar tolworthi, but only Def1 and Def2 showed a bacteriostatic effect against Staphylococcus epidermidis. None of the defensins showed activity against the Gram-negative bacteria Escherichia coli and Pseudomonas entomophila or against the yeast Saccharomyces cerevisiae. All three defensins were transcriptionally upregulated following a bacterial challenge, suggesting a key role in the immunity of T. castaneum against bacterial pathogens. Phylogenetic analysis showed that defensins from T. castaneum, mealworms, Udo longhorn beetle and houseflies cluster within a well-defined clade of insect defensins. We conclude that T. castaneum defensins are primarily active against Gram-positive bacteria and that other AMPs may play a more prominent role against Gram-negative species. PMID:26522790

  4. Recent Northern Hemisphere tropical expansion primarily driven by black carbon and tropospheric ozone.

    PubMed

    Allen, Robert J; Sherwood, Steven C; Norris, Joel R; Zender, Charles S

    2012-05-16

    Observational analyses have shown the width of the tropical belt increasing in recent decades as the world has warmed. This expansion is important because it is associated with shifts in large-scale atmospheric circulation and major climate zones. Although recent studies have attributed tropical expansion in the Southern Hemisphere to ozone depletion, the drivers of Northern Hemisphere expansion are not well known and the expansion has not so far been reproduced by climate models. Here we use a climate model with detailed aerosol physics to show that increases in heterogeneous warming agents--including black carbon aerosols and tropospheric ozone--are noticeably better than greenhouse gases at driving expansion, and can account for the observed summertime maximum in tropical expansion. Mechanistically, atmospheric heating from black carbon and tropospheric ozone has occurred at the mid-latitudes, generating a poleward shift of the tropospheric jet, thereby relocating the main division between tropical and temperate air masses. Although we still underestimate tropical expansion, the true aerosol forcing is poorly known and could also be underestimated. Thus, although the insensitivity of models needs further investigation, black carbon and tropospheric ozone, both of which are strongly influenced by human activities, are the most likely causes of observed Northern Hemisphere tropical expansion.

  5. Drive program documentation

    NASA Technical Reports Server (NTRS)

    Graham, S.

    1979-01-01

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

  6. Control rod drive

    DOEpatents

    Hawke, Basil C.

    1986-01-01

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

  7. Direct drive wind turbine

    DOEpatents

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

    2007-02-27

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

  8. Direct drive wind turbine

    DOEpatents

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

    2006-07-11

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

  9. Direct drive wind turbine

    DOEpatents

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

    2006-10-10

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

  10. Direct drive wind turbine

    DOEpatents

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

    2006-09-19

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

  11. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.

    1960-05-24

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

  12. Self-driving carsickness.

    PubMed

    Diels, Cyriel; Bos, Jelte E

    2016-03-01

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

  13. Dementia and driving.

    PubMed

    O'Neill, D; Neubauer, K; Boyle, M; Gerrard, J; Surmon, D; Wilcock, G K

    1992-04-01

    Many European countries test cars, but not their drivers, as they age. There is evidence to suggest that human factors are more important than vehicular factors as causes of motor crashes. The elderly also are involved in more accidents per distance travelled than middle-aged drivers. As the UK relies on self-certification of health by drivers over the age of 70 years, we examined the driving practices of patients with dementia attending a Memory Clinic. Nearly one-fifth of 329 patients with documented dementia continued to drive after the onset of dementia, and impaired driving ability was noted in two-thirds of these. Their families experienced great difficulty in persuading patients to stop driving, and had to invoke outside help in many cases. Neuropsychological tests did not help to identify those who drove badly while activity of daily living scores were related to driving ability. These findings suggest that many patients with dementia drive in an unsafe fashion after the onset of the illness. The present system of self-certification of health by the elderly for driver-licensing purposes needs to be reassessed.

  14. Self-driving carsickness.

    PubMed

    Diels, Cyriel; Bos, Jelte E

    2016-03-01

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

  15. Hydraulic drive system prevents backlash

    NASA Technical Reports Server (NTRS)

    Acord, J. D.

    1965-01-01

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

  16. The effects of altitude training are mediated primarily by acclimatization, rather than by hypoxic exercise.

    PubMed

    Levine, B D; Stray-Gundersen, J

    2001-01-01

    For training at altitude to be effective, it must provide some advantage above and beyond similar training at sea level. This advantage could be provided by: 1) acclimatization to altitude which improves oxygen transport and/or utilization; 2) hypoxic exercise which "intensifies" the training stimulus; or 3) some combination of both. Controlled studies of "typical" altitude training, involving both altitude acclimatization and hypoxic exercise have never been shown to improve sea level performance. This failure has been attributed to reduced training loads at altitude. One approach developed by Levine and Stray-Gundersen, called "living high-training low" has been shown to improve sea level performance over events lasting 8-20 minutes. This strategy combines altitude acclimatization (2,500 m) with low altitude training to get the optimal effect. The opposite strategy, "living low-training high" is proposed by Dr. Hoppeler in this debate. In defense of the primacy of the altitude acclimatization effect, data will be presented to support the following: 1). Living high-training low clearly improves performance in athletes of all abilities; 2). The mechanism of this improvement is primarily an increase in erythropoietin leading to increased red cell mass, VO2max, and running performance; 3). Rather than intensifying the training stimulus, training at altitude leads to the opposite effect--reduced speeds, reduced power output, reduced oxygen flux--and, following the principal of symmorphosis, is not likely to provide any advantage for a well trained athlete; 4). At the moderate altitudes used by most athletes, resting oxygen delivery to skeletal muscle is well preserved, arguing against any detrimental effect on "protein synthesis"; 5). It is possible however, that at significantly higher altitudes, acclimatization leads to appetite suppression, inhibition of protein synthesis, muscle wasting, excessive ventilatory work, and metabolic compensation that is NOT

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2015-02-01

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

  19. Pituitary tumor disappearance in a patient with newly diagnosed acromegaly primarily treated with octreotide LAR.

    PubMed

    Resmini, E; Murialdo, G; Giusti, M; Boschetti, M; Minuto, F; Ferone, D

    2005-02-01

    We describe the case of an acromegalic patient primarily treated with octreotide LAR in whom the pituitary tumor disappeared after 18 months of treatment. A 68-yr-old woman, with clinical suspicion of acromegaly, was admitted to our Unit with the ultrasonographical evidence of cardiac hypertrophy, arrhythmias, right branch block and interatrial septum aneurism. She referred hands and feet enlargement since the age of 30 and facial disfigurements since the age of 50. At the age of 45 she underwent surgery for carpal tunnel syndrome and at the age of 61 an euthyroid nodular goiter was diagnosed. Hormonal evaluation showed elevated circulating GH levels (25+/-3.2 ng/ml), not suppressible after oral glucose load, and elevated IGF-I levels (646 ng/ml), whereas the remaining pituitary function was normal. Visual perimetry was normal, whereas magnetic resonance imaging (MRI) showed an intrasellar pituitary adenoma with maximal diameter of 9 mm. In order to improve cardiovascular function before surgery, the patient started octreotide LAR 20 mg every 4 weeks for 3 months. Then based on IGF-I values, the dose was adjusted to 30 mg. After 6 months a second MRI showed significant tumor reduction (>50% of baseline maximal diameter), GH and IGF-I were within the normal range and the patient continued the treatment. After one-year therapy, an improvement of cardiac alterations was recorded and the patient was referred to the neurosurgeon. However, she refused the operation. At 18-month follow-up, MRI showed the complete disappearance of direct and indirect signs of pituitary adenoma. To our knowledge, this is the first case of complete radiological remission of pituitary tumor during octreotide LAR treatment in acromegaly.

  20. In vitro metabolism of piperaquine is primarily mediated by CYP3A4

    PubMed Central

    Lee, Tina Ming-Na; Huang, Liusheng; Johnson, Marla K.; Lizak, Patricia; Kroetz, Deanna; Aweeka, Francesca; Parikh, Sunil

    2016-01-01

    Piperaquine (PQ) is part of a first-line treatment regimen for Plasmodium falciparum malaria recommended by the World Health Organization (WHO). We aimed to determine the major metabolic pathway(s) of PQ in vitro. A reliable, validated tandem mass spectrometry method was developed. Concentrations of PQ were measured after incubation with both human liver microsomes (HLMs) and expressed cytochrome P450 enzymes (P450s). In pooled HLMs, incubations with an initial PQ concentration of 0.3 µM resulted in a 34.8 ± 4.9% loss of substrate over 60 min, corresponding to a turnover rate of 0.009 min−1 (r2 = 0.9223). Miconazole, at nonspecific P450 inhibitory concentrations, resulted in almost complete inhibition of PQ metabolism. The greatest inhibition was demonstrated with selective CYP3A4 (100%) and CYP2C8 (66%) inhibitors. Using a mixture of recombinant P450 enzymes, turnover for PQ metabolism was estimated as 0.0099 min−1; recombinant CYP3A4 had a higher metabolic rate (0.017 min−1) than recombinant CYP2C8 (p < .0001). Inhibition of CYP3A4-mediated PQ loss was greatest using the selective inhibitor ketoconazole (9.1 ± 3.5% loss with ketoconazole vs 60.7 ± 5.9% with no inhibitor, p < .0001). In summary, the extent of inhibition of in vitro metabolism with ketoconazole (83%) denotes that PQ appears to be primarily catalyzed by CYP3A4. Further studies to support these findings through the identification and characterization of PQ metabolites are planned. PMID:22671777

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

    PubMed

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

    2014-01-01

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

  2. Glutamate Synaptic Inputs to Ventral Tegmental Area Neurons in the Rat Derive Primarily from Subcortical Sources

    PubMed Central

    Omelchenko, Natalia; Sesack, Susan R.

    2007-01-01

    cortical sources of excitation expressing VGlut1 and are more likely to drive the behaviorally-linked bursts in dopamine cells that signal future expectancy or attentional shifting. PMID:17391856

  3. Driving with diabetes: precaution, not prohibition, is the proper approach.

    PubMed

    Kohrman, Daniel B

    2013-03-01

    Safety issues posed by driving with diabetes are primarily related to severe hypoglycemia, yet some public authorities rely on categorical restrictions on drivers with diabetes. This approach is misguided. Regulation of all drivers with diabetes, or all drivers using insulin, ignores the diversity of people with diabetes and fails to focus on the subpopulation posing the greatest risk. Advances in diabetes care technology and understanding of safety consequences of diabetes have expanded techniques available to limit risks of driving with diabetes. New means of insulin administration and blood glucose monitoring offer greater ease of anticipating and preventing hypoglycemia, and thus, limit driving risk for persons with diabetes. So too do less sophisticated steps taken by people with diabetes and the health care professionals they consult. These include adoption and endorsement of safety-sensitive behaviors, such as testing before a drive and periodic testing on longer trips. Overall, and in most individual cases, driving risks for persons with diabetes are less than those routinely tolerated by our society. Examples include freedom to drive in dangerous conditions and lax regulation of drivers in age and medical cohorts with elevated overall rates of driving mishaps. Data linking specific diabetes symptoms or features with driving risk are quite uncertain. Hence, there is much to recommend: a focus on technological advances, human precautions, and identifying individuals with diabetes with a specific history of driving difficulty. By contrast, available evidence does not support unfocused regulation of all or most drivers with diabetes.

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

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178... MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined...

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

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 3 2014-10-01 2014-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178... MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined...

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

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 3 2012-10-01 2012-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178... MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined...

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

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 3 2013-10-01 2013-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178... MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined...

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

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 3 2011-10-01 2011-10-01 false Specification MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined in subpart G of part 173 of this subchapter. 178... MC 331; cargo tank motor vehicle primarily for transportation of compressed gases as defined...

  9. 49 CFR 37.107 - Acquisition of passenger rail cars by private entities primarily engaged in the business of...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... in providing specified public transportation to extend its useful life for ten years or more, or... entities primarily engaged in the business of transporting people. 37.107 Section 37.107 Transportation... entities primarily engaged in the business of transporting people. (a) A private entity which is...

  10. 49 CFR 37.107 - Acquisition of passenger rail cars by private entities primarily engaged in the business of...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... in providing specified public transportation to extend its useful life for ten years or more, or... entities primarily engaged in the business of transporting people. 37.107 Section 37.107 Transportation... entities primarily engaged in the business of transporting people. (a) A private entity which is...

  11. Children's Theories and the Drive to Explain

    NASA Astrophysics Data System (ADS)

    Schwitzgebel, Eric

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

  12. Passerine exposure to primarily PCDFs and PCDDs in the river floodplains near Midland, Michigan, USA.

    PubMed

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

    2010-05-01

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

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

    PubMed Central

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

    2009-01-01

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

  14. Young children's hand contact activities: an observational study via videotaping in primarily outdoor residential settings.

    PubMed

    Auyeung, Willa; Canales, Robert A; Beamer, Paloma; Ferguson, Alesia C; Leckie, James O

    2006-09-01

    Microlevel activity time series (MLATS) data were gathered on hand contact activities of 38 children (1-6 years old) by videotaping in primarily outdoor residential environments. The videotape recordings were then translated into text files using a specialized software called VirtualTimingDevicetrade mark. Contact frequency (contacts/h), duration per contact (s/contact), and hourly contact duration (min/h) were summarized for outdoor hand contacts with 15 distinct object/surface categories ("Animal", "Body", "Clothes/Towels", "Fabric", "Floor", "Food", "Footwear", "Metal", "Non-dietary Water", "Paper/Wrapper", "Plastic", "Rock/Brick", "Toys", "Vegetation/Grass", and "Wood") and two aggregate object/surface categories ("Non-dietary objects/surfaces" and "Total objects/surfaces"). For outdoor both hand contacts with "Total objects/surfaces", contact frequencies ranged from 229.9 to 1517.7 contacts/h, median durations/contact ranged from < 1 to 5 s, and hourly contact durations ranged from 42.6 to 102.2 m/h. The data were analyzed for significant differences in hand contact activities as a function of (1) age, (2) location, (3) gender, and (4) hand. Significant differences (P < or = 0.05) were found for all four factors analyzed. Hourly contact durations with "Non-dietary objects/surfaces" and "Total objects/surfaces" increased with age (P = 0.01, rs = 0.42 and P = 0.005, rs = 0.46, respectively), while contact frequencies and hourly contact durations with "Wood" decreased with age (P = 0.02, rs = -0.38 and P = 0.05, rs = -0.32, respectively). Location was found to affect contact frequencies and hourly contact durations with certain objects/surfaces. For example, contact frequencies and hourly contact durations with "Fabric" were higher indoors (P = 0.02 for both), while contact frequencies and hourly contact durations with "Vegetation/Grass" were higher outdoors (P = 0.02 and P = 0.04, respectively). Girls had longer hourly contact durations with "Footwear" (P = 0

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

    PubMed

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

    2011-06-01

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

  16. Mental workload and driving

    PubMed Central

    Paxion, Julie; Galy, Edith; Berthelon, Catherine

    2014-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  18. Improvement of the energy conversion efficiency of Chlorella pyrenoidosa biomass by a three-stage process comprising dark fermentation, photofermentation, and methanogenesis.

    PubMed

    Xia, Ao; Cheng, Jun; Ding, Lingkan; Lin, Richen; Huang, Rui; Zhou, Junhu; Cen, Kefa

    2013-10-01

    The effects of pre-treatment methods on saccharification and hydrogen fermentation of Chlorella pyrenoidosa biomass were investigated. When raw biomass and biomass pre-treated by steam heating, by microwave heating, and by ultrasonication were used as feedstock, the hydrogen yields were only 8.8-12.7 ml/g total volatile solids (TVS) during dark fermentation. When biomass was pre-treated by steam heating with diluted acid and by microwave heating with diluted acid, the dark hydrogen yields significantly increased to 75.6 ml/g TVS and 83.3 ml/g TVS, respectively. Steam heating with diluted acid is the preferred pre-treatment method of C. pyrenoidosa biomass to improve hydrogen yield during dark fermentation and photofermentation, which is followed by methanogenesis to increase energy conversion efficiency (ECE). A total hydrogen yield of 198.3 ml/g TVS and a methane yield of 186.2 ml/g TVS corresponding to an overall ECE of 34.0% were obtained through the three-stage process (dark fermentation, photofermentation, and methanogenesis).

  19. Effect of carbon source and COD/NO₃⁻-N ratio on anaerobic simultaneous denitrification and methanogenesis for high-strength wastewater treatment.

    PubMed

    Xie, Li; Chen, Jinrong; Wang, Rui; Zhou, Qi

    2012-06-01

    The effect of carbon source and COD/NO(3)(-)-N ratio on denitrification and methanogenesis in mixed methanogenic matrix was investigated in this study. Industrial wastewater, anaerobic treated cassava stillage (CS) and glucose synthetic wastewater were used as carbon sources respectively for comparison. Experimental results showed that denitrification was the main nitrate reduction pathway for all COD/NO(3)(-)-N ratios tested in two substrates. Simultaneous denitrification and methanogenesis occurred at COD/NO(3)(-)-N higher than 7 regardless of carbon sources. Incomplete denitrification was observed at COD/NO(3)(-)-N ratio below 7 in both the anaerobic effluent of CS and glucose-fed cultures due to the insufficient available organic carbon. The nature of carbon sources was observed to play a key role in the nitrate and organic carbon utilization rates. COD/NO(3)(-)-N ratio had a strong effect on the organic matter utilization pathways. Methanization consumed more organic matter than denitrification with further increase of COD/NO(3)(-)-N ratio above 7 in two substrates. Results of VFA variation suggested that propionate and butyrate were preferably utilized by the denitrifiers than acetate.

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

    PubMed

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

    2016-01-01

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

  1. Direct Drive for Low Power Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.

    2005-01-01

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

  2. Predicting underage drinking and driving behaviors.

    PubMed

    Grube, J W; Voas, R B

    1996-12-01

    A social-psychological model of underage drinking and driving (DUI) and riding with drinking drivers (RWDD) was tested with data from a random digit dial telephone survey of 706 16-20-year-old drivers from seven western states in the United States. Consistent with the model, a structural equations analysis indicated that DUI and RWDD were primarily predicted by (a) expectancies regarding the physical risks of DUI, (b) normative beliefs about the extent to which friends would disapprove of DUI, (c) control beliefs about the ease or difficulty of avoiding DUI and RWDD and (d) drinking. Expectancies concerning enforcement had a significant effect on RWDD, but not on DUI. Among the background and environmental variables included in the analysis, only night-time driving and age had significant direct effects on DUI and RWDD. Drinking and involvement in risky driving had indirect effects on DUI and RWDD that were mediated through expectancies and normative beliefs. Males, European Americans, Latinos, respondents who drove more frequently and respondents who were less educated held beliefs that were more favorable toward DUI and RWDD, drank more and engaged more frequently in risky driving. As a result, such individuals may be at greater risk for DUI and RWDD. PMID:8997765

  3. Fundamental limitations on 'warp drive' spacetimes

    NASA Astrophysics Data System (ADS)

    Lobo, Francisco S. N.; Visser, Matt

    2004-12-01

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

  4. Driving Anger and Driving Behavior in Adults with ADHD

    ERIC Educational Resources Information Center

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

    2006-01-01

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

  5. DEDRICK DRIVE, LOOKING NORTH FROM SOUTH END OF DEDRICK DRIVE ...

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

    DEDRICK DRIVE, LOOKING NORTH FROM SOUTH END OF DEDRICK DRIVE NEAR BUILDING 80 - Pacific Coast Torpedo Station, Keyport Industrial District, Both sides of Second Street, between Dedrick Drive and Liberty Bay and one building west of Dedrick Drive and south of Second Street, Keyport, Kitsap County, WA

  6. Driving anger in Malaysia.

    PubMed

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

    2014-10-01

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

  7. U.S. DRIVE

    SciTech Connect

    2012-03-16

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

  8. Ceramic vane drive joint

    DOEpatents

    Smale, Charles H.

    1981-01-01

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

  9. Current drive, anticurrent drive, and balanced injection

    SciTech Connect

    von Goeler, S.; Stevens, J.; Beiersdorfer, P.; Bell, R.; Bernabei, S.; Bitter, M.; Cavallo, A.; Chu, T.K.; Fishman, H.; Hill, K.

    1987-08-01

    In lower hybrid (LH) discharges, the number of suprathermal electrons is limited by the upper bound on the current density from the q = 1 condition, which is caused by the onset of the m = 1 MHD instability. The stored energy of suprathermal electrons, measured in terms of a poloidal beta, scales with plasma current as I/sub p//sup -1/. Potentially, these bounds represent very restrictive conditions for heating in larger machines. Consequently, it seems necessary to perform experiments where the electrons are driven in both directions, parallel and antiparallel to the magnetic field, i.e., bidirectional scenarios like anticurrent drive or balanced injection. Data from PLT relevant to these ideas are discussed. 6 refs., 4 figs.

  10. LCLS Injector Drive Laser

    SciTech Connect

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

    2007-11-02

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

  11. Pulsation driving and convection

    NASA Astrophysics Data System (ADS)

    Antoci, Victoria

    2015-08-01

    Convection in stellar envelopes affects not only the stellar structure, but has a strong impact on different astrophysical processes, such as dynamo-generated magnetic fields, stellar activity and transport of angular momentum. Solar and stellar observations from ground and space have shown that the turbulent convective motion can also drive global oscillations in many type of stars, allowing to study stellar interiors at different evolutionary stages. In this talk I will concentrate on the influence of convection on the driving of stochastic and coherent pulsations across the Hertzsprung-Russell diagram and give an overview of recent studies.

  12. CONTROL ROD DRIVE

    DOEpatents

    Chapellier, R.A.; Rogers, I.

    1961-06-27

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

  13. No Pass, No Drive?

    ERIC Educational Resources Information Center

    Zirkel, Perry A.

    2001-01-01

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

  14. Drive-Through Training

    ERIC Educational Resources Information Center

    Carter, Margie

    2010-01-01

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

  15. COMMENT: No warp drive

    NASA Astrophysics Data System (ADS)

    Coule, D. H.

    1998-08-01

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

  16. Magnetized drive fluids

    SciTech Connect

    Rosensweig, R.E.; Zahn, M.

    1986-04-01

    A process is described for recovering a first fluid from a porous subterranean formation which comprises injecting a displacement fluid in an effective amount to displace the first fluid, injecting a ferrofluid, applying a magnetic field containing a gradient of field intensity within the formation, driving the displacement fluid through the formation with the ferrofluid and recovering first fluid.

  17. DrivePy

    SciTech Connect

    King, Ryan; Guo, Yi

    2014-08-30

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

  18. CSI: Hard Drive

    ERIC Educational Resources Information Center

    Sturgeon, Julie

    2008-01-01

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

  19. Teachers with Drive

    ERIC Educational Resources Information Center

    Coggins, Celine; Diffenbaugh, P. K.

    2013-01-01

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

  20. Driving While Intoxicated.

    ERIC Educational Resources Information Center

    Brick, John

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  2. Identifying Periods of Drowsy Driving Using EEG

    PubMed Central

    Brown, Timothy; Johnson, Robin; Milavetz, Gary

    2013-01-01

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

  3. Identifying periods of drowsy driving using EEG.

    PubMed

    Brown, Timothy; Johnson, Robin; Milavetz, Gary

    2013-01-01

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

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

    PubMed

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

    2010-10-13

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

  5. [Driving ability with multiple sclerosis].

    PubMed

    Küst, J; Dettmers, C

    2014-07-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

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

    PubMed Central

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

    2015-01-01

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

  8. Advanced Motor Drives Studies

    NASA Technical Reports Server (NTRS)

    Ehsani, M.; Tchamdjou, A.

    1997-01-01

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

  9. Forces Driving Chaperone Action.

    PubMed

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

    2016-07-14

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

  10. Drive-by-Downloads

    SciTech Connect

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

    2010-02-01

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

  11. Gear Drive Testing

    NASA Technical Reports Server (NTRS)

    1982-01-01

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

  12. Environmental Crack Driving Force

    NASA Astrophysics Data System (ADS)

    Hall, M. M.

    2013-03-01

    The effect of environment on the crack driving force is considered, first by assuming quasistatic extension of a stationary crack and second, by use of stress corrosion cracking (SCC) crack growth rate models developed previously by this author and developed further here. A quasistatic thermodynamic energy balance approach, of the Griffith-Irwin type, is used to develop stationary crack threshold expressions, tilde{J}_c , which represent the conjoint mechanical and electrochemical conditions, below which stationary cracks are stable. Expressions for the electrochemical crack driving force (CDF) were derived using an analysis that is analogous to that used by Irwin to derive his "strain energy release rate," G, which Rice showed as being equivalent to his mechanical CDF, J. The derivations show that electrochemical CDFs both for active path dissolution (APD) and hydrogen embrittlement (HE) mechanisms of SCC are simply proportional to Tafel's electrochemical anodic and cathodic overpotentials, η a and η c, respectively. Phenomenological SCC models based on the kinetics of APD and HE crack growth are used to derive expressions for the kinetic threshold, J scc, below which crack growth cannot be sustained. These models show how independent mechanical and environmental CDFs may act together to drive SCC crack advance. Development of a user-friendly computational tool for calculating Tafel's overpotentials is advocated.

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

    ERIC Educational Resources Information Center

    Swisher, John D.; Bibeau, Daniel

    1987-01-01

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

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

    PubMed

    Musicant, Oren; Lotan, Tsippy; Albert, Gila

    2015-12-01

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

  15. Drive alignment pays maintenance dividends

    SciTech Connect

    Fedder, R.

    2008-12-15

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

  16. Drive Diagnostic Filter Wheel Control

    SciTech Connect

    Uhlich, D.

    2007-07-17

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

  17. 50 CFR 23.62 - What factors are considered in making a finding of not for primarily commercial purposes?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION... INTERNATIONAL TRADE IN ENDANGERED SPECIES OF WILD FAUNA AND FLORA (CITES) Factors Considered in Making Certain... satisfied that the specimen is not to be used for primarily commercial purposes. Trade in Appendix-I...

  18. 50 CFR 23.62 - What factors are considered in making a finding of not for primarily commercial purposes?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION... INTERNATIONAL TRADE IN ENDANGERED SPECIES OF WILD FAUNA AND FLORA (CITES) Factors Considered in Making Certain... satisfied that the specimen is not to be used for primarily commercial purposes. Trade in Appendix-I...

  19. 50 CFR 23.62 - What factors are considered in making a finding of not for primarily commercial purposes?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION... INTERNATIONAL TRADE IN ENDANGERED SPECIES OF WILD FAUNA AND FLORA (CITES) Factors Considered in Making Certain... satisfied that the specimen is not to be used for primarily commercial purposes. Trade in Appendix-I...

  20. 50 CFR 23.62 - What factors are considered in making a finding of not for primarily commercial purposes?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... FISH AND WILDLIFE SERVICE, DEPARTMENT OF THE INTERIOR (CONTINUED) TAKING, POSSESSION, TRANSPORTATION... INTERNATIONAL TRADE IN ENDANGERED SPECIES OF WILD FAUNA AND FLORA (CITES) Factors Considered in Making Certain... satisfied that the specimen is not to be used for primarily commercial purposes. Trade in Appendix-I...

  1. Offset Compound Gear Drive

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  2. Base drive circuit

    DOEpatents

    Lange, Arnold C.

    1995-01-01

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

  3. Base drive circuit

    DOEpatents

    Lange, A.C.

    1995-04-04

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

  4. Modular droplet actuator drive

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  5. Oil well pump driving unit

    SciTech Connect

    Gilbertson, T.A.

    1984-02-21

    An oil well pump driving unit with a horizontally disposed hydraulic cylinder having a cylinder rod coupled to a drive rope extending into a pumping tee-stuffing box arrangement for driving the sucker rod string leading to a conventional oil well reciprocating pump. The drive rope extends over a first rotating sheave mounted near the wellhead and passes over a second rotating sheave mounted on a carriage which traverses a carriage channel in a draw works on which the hydraulic cylinder is mounted. A hydraulic drive/control system utilizing limit switches on the draw works provides control over the stroke position, the stroke length, and the stroke rate.

  6. Advances in traction drive technology

    NASA Technical Reports Server (NTRS)

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

    1983-01-01

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

  7. Turbulent current drive

    NASA Astrophysics Data System (ADS)

    Garbet, X.; Esteve, D.; Sarazin, Y.; Dif-Pradalier, G.; Ghendrih, P.; Grandgirard, V.; Latu, G.; Smolyakov, A.

    2014-11-01

    The Ohm's law is modified when turbulent processes are accounted for. Besides an hyper-resistivity, already well known, pinch terms appear in the electron momentum flux. Moreover it appears that turbulence is responsible for a source term in the Ohm's law, called here turbulent current drive. Two terms contribute to this source. The first term is a residual stress in the momentum flux, while the second contribution is an electro-motive force. A non zero average parallel wave number is needed to get a finite source term. Hence a symmetry breaking mechanism must be invoked, as for ion momentum transport. E × B shear flows and turbulence intensity gradients are shown to provide similar contributions. Moreover this source term has to compete with the collision friction term (resistivity). The effect is found to be significant for a large scale turbulence in spite of an unfavorable scaling with the ratio of the electron to ion mass. Turbulent current drive appears to be a weak effect in the plasma core, but could be substantial in the plasma edge where it may produce up to 10 % of the local current density.

  8. Polar drive on OMEGA

    NASA Astrophysics Data System (ADS)

    Radha, P. B.; Marshall, F. J.; Boehly, T. R.; Collins, T. J. B.; Craxton, R. S.; Edgell, D.; Epstein, R.; Frenje, J.; Goncharov, V. N.; Marozas, J. A.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Petrasso, R. D.; Sangster, T. C.; Shvydky, A.; Skupsky, S.

    2013-11-01

    High-convergence polar-drive experiments are being conducted on OMEGA [T. R. Boehly et al., Opt. Commum. 133, 495 (1997)] using triple-picket laser pulses. The goal of OMEGA experiments is to validate modeling of oblique laser deposition, heat conduction in the presence of nonradial thermal gradients in the corona, and implosion energetics in the presence of laser-plasma interactions such as crossed-beam energy transfer. Simulated shock velocities near the equator, where the beams are obliquely incident, are within 5% of experimentally inferred values in warm plastic shells, well within the required accuracy for ignition. High, near-one-dimensional areal density is obtained in warm-plastic-shell implosions. Simulated backlit images of the compressing core are in good agreement with measured images. Outstanding questions that will be addressed in the future relate to the role of cross-beam transfer in polar drive irradiation and increasing the energy coupled into the target by decreasing beam obliquity.

  9. Glaucoma and Driving: On-Road Driving Characteristics

    PubMed Central

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

    2016-01-01

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

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

    SciTech Connect

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

    1983-04-01

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

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

    PubMed

    Lovley, D R; Klug, M J

    1983-04-01

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

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

    PubMed

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

    2014-01-01

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

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

    SciTech Connect

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

    1987-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    PubMed

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

    2015-08-01

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

  16. Automatism and driving offences.

    PubMed

    Rumbold, John

    2013-10-01

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

  17. Magnetostrictive direct drive motors

    NASA Technical Reports Server (NTRS)

    Naik, Dipak; Dehoff, P. H.

    1992-01-01

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

  18. Automatism and driving offences.

    PubMed

    Rumbold, John

    2013-10-01

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

  19. Head tilt during driving.

    PubMed

    Zikovitz, D C; Harris, L R

    1999-05-01

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

  20. [Epilepsy and driving].

    PubMed

    Matsuura, Masato

    2014-05-01

    In Japan, the Road Traffic Act was amended in June 2013, including new penalty to false statement in a disease condition declaration form, and new voluntary notification system for a doctor who is aware that a person is at high risk for traffic accident and in possession of a driver license. Moreover, New Criminal Law Act was established in November 2013, including a prison sentence of up to 15 years for persons, who under the influence of specific drugs or diseases, causing death or injury to other persons by driving a motor vehicle. Both laws are supposed to be enforced during 2014, after additional resolutions including the review of the laws after five years, considerations so as not to create discrimination due to diseases, etc are examined.

  1. [Epilepsy and driving].

    PubMed

    Matsuura, Masato

    2014-05-01

    In Japan, the Road Traffic Act was amended in June 2013, including new penalty to false statement in a disease condition declaration form, and new voluntary notification system for a doctor who is aware that a person is at high risk for traffic accident and in possession of a driver license. Moreover, New Criminal Law Act was established in November 2013, including a prison sentence of up to 15 years for persons, who under the influence of specific drugs or diseases, causing death or injury to other persons by driving a motor vehicle. Both laws are supposed to be enforced during 2014, after additional resolutions including the review of the laws after five years, considerations so as not to create discrimination due to diseases, etc are examined. PMID:24912298

  2. QUICK RELEASABLE DRIVE

    DOEpatents

    Dickson, J.J.

    1958-07-01

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

  3. Rotary drive mechanism

    DOEpatents

    Kenderdine, Eugene W.

    1991-01-01

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

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

    SciTech Connect

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

    2011-02-01

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

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

    NASA Technical Reports Server (NTRS)

    Cosgrove, D. J.

    1987-01-01

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

  6. [Driving license and mellitus diabetes].

    PubMed

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

    2015-10-01

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

  7. Sequenced drive for rotary valves

    DOEpatents

    Mittell, Larry C.

    1981-01-01

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

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

    PubMed

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

    2016-03-01

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

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

    PubMed

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

    2016-03-01

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

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

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

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

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

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

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

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

    PubMed

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

    2016-07-01

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

  13. Effects of Polychlorinated Biphenyl Congener Concentration and Sediment Supplementation on Rates of Methanogenesis and 2,3,6-Trichlorobiphenyl Dechlorination in an Anaerobic Enrichment

    PubMed Central

    Boyle, Alfred W.; Blake, Cheryl K.; Price, W. Allen; May, Harold D.

    1993-01-01

    We have employed a method of enrichment that allows us to significantly increase the rate of reductive polychlorinated biphenyl (PCB) dechlorination. This method shortens the time required to investigate the effects that culture conditions have on dechlorination and provides an estimate of the potential activity of the PCB-dechlorinating anaerobes. The periodic supplementation of sterile sediment and PCB produced an enhanced, measurable, and sustained rate of dechlorination. We observed volumetric rates of the dechlorination of 2,3,6-trichlorobiphenyl (2,3,6-CB) to 2,6-dichlorobiphenyl (2,6-CB) of more than 300 μmol liter-1 day-1 when the cultures were supplemented daily. A calculation of this activity that is based on an estimate of the number of dechlorinating anaerobes present indicates that 1.13 pmol of 2,3,6-CB was dechlorinated to 2,6-CB day-1 bacterial cell-1. This rate is similar to that of the reductive dechlorination of 3-chlorobenzoate by Desulfomonile tiedjei. Methanogenesis declined from 585.3 to 125.9 μmol of CH4 liter-1 day-1, while dechlorination increased from 8.2 to 346.0 μmol of 2,3,6-CB dechlorinated to 2,6-CB liter-1 day-1. PMID:16349045

  14. Small-cell carcinoma of the lung: patterns of treatment failure in patients treated primarily by chemotherapy

    SciTech Connect

    Ali, M.M.; Hazra, T.A.

    1984-08-01

    Treatment failure patterns in 75 patients with small-cell carcinoma of the lung who were treated primarily by chemotherapy were reviewed. Of 32 patients with disease considered to be localized but who did not undergo complete staging work-ups, 23 had metastasis to the chest, 11 to the central nervous system, four to bone, and two to the lymph nodes. Of 33 patients with documented distant metastasis, 23 had metastasis to the chest, 14 to the central nervous system, 15 to bone, and six to the lymph nodes. Median survival times of patients showing complete response to treatment was 17 months; for those showing partial response it was 7 months.

  15. Natural death while driving.

    PubMed

    Oström, M; Eriksson, A

    1987-07-01

    Of sudden natural deaths while driving, 126 occurred during 1980 through 1985 in the northern half of Sweden. The mean age of the 69 car driver victims was 59 years, considerably higher than that of traumatic car deaths, and all but 2 were males. The mean age of 57 operators of other vehicles was 66 years, and of these, 6 were women. Seven car drivers were stricken during commercial employment. Most accidents occurred during daytime and the distribution of the weekdays was fairly even. Ischemic heart disease accounted for 112 deaths, and other cardiovascular diseases for an additional 9 deaths. Only 1/5 of the victims experienced previous symptoms of disease. Out of at least 31 other persons at risk in the car deaths, only 2 passengers suffered minor injuries. The trauma in the deceased was in most cases minor in both car and other vehicle deaths. Property damage was also minimal. At least 1/3 of the drivers were able to stop the car before becoming unconscious. In none of the car cases was alcohol detected in the blood, while alcohol was identified in at least 2 of the other vehicle victims. The findings here agree with previous studies that natural deaths at the wheel are fairly uncommon, and that the risk for other persons is not significant. The value of adequate postmortem examinations of drivers dying in traffic is stressed--natural deaths can otherwise be overlooked. PMID:3612079

  16. Drive-By Pharming

    NASA Astrophysics Data System (ADS)

    Stamm, Sid; Ramzan, Zulfikar; Jakobsson, Markus

    This paper describes an attack concept termed Drive-by Pharming where an attacker sets up a web page that, when simply viewed by the victim (on a JavaScript-enabled browser), attempts to change the DNS server settings on the victim's home broadband router. As a result, future DNS queries are resolved by a DNS server of the attacker's choice. The attacker can direct the victim's Internet traffic and point the victim to the attacker's own web sites regardless of what domain the victim thinks he is actually going to, potentially leading to the compromise of the victim's credentials. The same attack methodology can be used to make other changes to the router, like replacing its firmware. Routers could then host malicious web pages or engage in click fraud. Since the attack is mounted through viewing a web page, it does not require the attacker to have any physical proximity to the victim nor does it require the explicit download of traditional malicious software. The attack works under the reasonable assumption that the victim has not changed the default management password on their broadband router.

  17. Little-known truths, quirky anecdotes, seething scandals, and even some science in the history of (primarily achievement) motivation.

    PubMed

    Weiner, Bernard

    2013-08-01

    This article presents a history of the study of motivation from approximately 1900-1975, focusing on achievement strivings and containing little-known and often surprising facts about the main contributors to this field. Four theorists are highlighted: David McClelland, Kurt Lewin, John Atkinson, and Fritz Heider, each associated with a different theoretical approach (respectively and in order of historical emergence: trait, Gestalt, expectancy/value, and attribution theory). A fifth conception, drive theory, is also represented. In addition, a number of individuals who influenced these theorists and others who followed them are discussed. The article emphasizes the interrelations between the theorists and the interaction between personal and scientific life.

  18. Handbook for Driving Knowledge Testing.

    ERIC Educational Resources Information Center

    Pollock, William T.; McDole, Thomas L.

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

  19. Bidirectional drive and brake mechanism

    NASA Technical Reports Server (NTRS)

    Swan, Scott A. (Inventor)

    1991-01-01

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

  20. Students: You... Alcohol and Driving.

    ERIC Educational Resources Information Center

    Department of Transportation, Washington, DC.

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

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

    PubMed

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

    2014-11-01

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

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

    PubMed

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

    2014-11-01

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

  3. Mating-type orthologous genes in the primarily homothallic Moniliophthora perniciosa, the causal agent of Witches' Broom Disease in cacao.

    PubMed

    Kües, Ursula; Navarro-González, Mónica

    2010-10-01

    The cacao-pathogenic Moniliophthora perniciosa C-biotype is a primarily homothallic Agaricomycete of which the genome has recently become available. Searching of the genome sequence with mating type proteins from other basidiomycetes detected one or possibly two potential genes for HD1 homeodomain transcription factors, 7 or possibly 8 genes for potential pheromone receptors and five genes for putative pheromone precursors. Apparently, the fungus possesses gene functions encoded in the tetrapolar basidiomycetes in the A and B mating loci, respectively. In the tetrapolar species, the A and B mating type genes govern formation of clamp cells at hyphal septa of the dikaryon and their fusion with sub-apical cells as well as mushroom production. The C-biotype forms fused clamp cells and also basidiocarps on mycelia germinated from basidiospores and their development might be controlled by the detected genes. It represents the first example of a primarily homothallic basidiomycete where A - and B -mating-type-like genes were found. Various strategies are discussed as how self-compatibility in presence of such genes can evolve. An A -mating-type like gene for an HD2 homeodomain transcription factor is, however, not included in the available sequence representing estimated 69% coverage of the haploid genome but there are non-mating genes for other homeodomain transcription factors of currently unknown function that are conserved in basidiomycetes and also various ascomycetes.

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

    SciTech Connect

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

    2012-07-15

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

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

    PubMed Central

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

    2013-01-01

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

  6. Driving difficulties in Parkinson's disease

    PubMed Central

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

    2011-01-01

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

  7. Quantum gates by periodic driving

    PubMed Central

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

    2016-01-01

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

  8. [Driving and health at work].

    PubMed

    Giorgio, Marie-Thérèse

    2015-09-01

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

  9. Electric vehicle drive systems

    NASA Astrophysics Data System (ADS)

    Appleyard, M.

    1992-01-01

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

  10. Linear Back-Drive Differentials

    NASA Technical Reports Server (NTRS)

    Waydo, Peter

    2003-01-01

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

  11. Oil well pump driving unit

    SciTech Connect

    Gilbertson, T. A.

    1984-11-06

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

  12. Oil well pump driving unit

    SciTech Connect

    Gilbertson, T.A.

    1982-03-23

    An oil well pumping apparatus which includes a submerged reciprocating pump mounted in a tubing arrangement communicating with the well head, a sucker rod string extending through the tubing arrangement and connected in driving relation with the pump, and a pumping tee and stuffing box arrangement mounted on the casing of the well at the well head and including a sealed drive rod arrangement in the stuffing box connected in driving relation to said sucker rod string, and a pump driving unit. The pump driving unit includes a hydraulic cylinder and support means for supporting the hydraulic cylinder over the stuffing box with the axis of the cylinder rod aligned with the axis of said stuffing box. A coupling means is provided for coupling the cylinder rod to the seal drive rod arrangement. A hydraulic drive -control unit is coupled to said in-out fluid line for operating the hydraulic cylinder to produce an operating cycle consisting of a hydraulic power upstroke and a gravity power downstroke.

  13. Electron Locking in Current Drive

    NASA Astrophysics Data System (ADS)

    McCollam, K. J.; Jarboe, T. R.; Nelson, B. A.; Orvis, D. J.; Raman, R.; Redd, A. J.; Smith, R. J.; Nagata, M.; Uyama, T.

    2000-10-01

    The traveling n=1, m~= q_edge magnetic distortion observed in the Helicity Injected Torus (HIT-II) during coaxial helicity injection (CHI) is responsible for some current profile relaxation. A model for electromotive current drive, called the electron locking model, can account for the results of current drive experiments in both the HIT-II and the original HIT devices. The most relevant of these results involve the the frequencies and directions of the mode itself, the E× B drift, and the electric current drift. In spherical tokamaks with CHI, electrode and coil polarities can be changed to control the relative directions of these drifts. Results from HIT-II experiments with different polarities are shown. These point out the character n=1, m~= q_edge mode, and suggest its role in CHI current drive. The electron locking model is presented, and is also discussed in the context of mean field electrodynamics. This model might also be applied to other types of current drive, such as rotating magnetic field (RMF) current drive, oscillating field current drive (OFCD), steady inductive helicity injection (SIHI), or Ohmic current drive in a reversed field pinch (RFP). These examples are discussed.

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Louka, Panagiota; Petropoulos, George; Papanikolaou, Ioannis

    2015-04-01

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

  16. Driving Performance Under Alcohol in Simulated Representative Driving Tasks

    PubMed Central

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

    2015-01-01

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

  17. Magnetic compression laser driving circuit

    DOEpatents

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

    1993-01-01

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

  18. Magnetic compression laser driving circuit

    DOEpatents

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

    1993-01-05

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

  19. Effect of Substrate Concentration on Carbon Isotope Fractionation during Acetoclastic Methanogenesis by Methanosarcina barkeri and M. acetivorans and in Rice Field Soil▿

    PubMed Central

    Goevert, Dennis; Conrad, Ralf

    2009-01-01

    Methanosarcina is the only acetate-consuming genus of methanogenic archaea other than Methanosaeta and thus is important in methanogenic environments for the formation of the greenhouse gases methane and carbon dioxide. However, little is known about isotopic discrimination during acetoclastic CH4 production. Therefore, we studied two species of the Methanosarcinaceae family, Methanosarcina barkeri and Methanosarcina acetivorans, and a methanogenic rice field soil amended with acetate. The values of the isotope enrichment factor (ɛ) associated with consumption of total acetate (ɛac), consumption of acetate-methyl (ɛac-methyl) and production of CH4 (ɛCH4) were an ɛac of −30.5‰, an ɛac-methyl of −25.6‰, and an ɛCH4 of −27.4‰ for M. barkeri and an ɛac of −35.3‰, an ɛac-methyl of −24.8‰, and an ɛCH4 of −23.8‰ for M. acetivorans. Terminal restriction fragment length polymorphism of archaeal 16S rRNA genes indicated that acetoclastic methanogenic populations in rice field soil were dominated by Methanosarcina spp. Isotope fractionation determined during acetoclastic methanogenesis in rice field soil resulted in an ɛac of −18.7‰, an ɛac-methyl of −16.9‰, and an ɛCH4 of −20.8‰. However, in rice field soil as well as in the pure cultures, values of ɛac and ɛac-methyl decreased as acetate concentrations decreased, eventually approaching zero. Thus, isotope fractionation of acetate carbon was apparently affected by substrate concentration. The ɛ values determined in pure cultures were consistent with those in rice field soil if the concentration of acetate was taken into account. PMID:19251888

  20. Stable isotope probing of acetate fed anaerobic batch incubations shows a partial resistance of acetoclastic methanogenesis catalyzed by Methanosarcina to sudden increase of ammonia level.

    PubMed

    Hao, Liping; Lü, Fan; Mazéas, Laurent; Desmond-Le Quéméner, Elie; Madigou, Céline; Guenne, Angéline; Shao, Liming; Bouchez, Théodore; He, Pinjing

    2015-02-01

    Ammonia inhibition represents a major operational issue for anaerobic digestion. In order to refine our understanding of the terminal catabolic steps in thermophilic anaerobic digestion under ammonia stress, we studied batch thermophilic acetate fed experiments at low (0.26 g L(-1)) and high (7.00 g L(-1)) Total Ammonia Nitrogen concentrations (TAN). Although methane production started immediately for all incubations and resulted in methane yields close to stoichiometric expectations, a 62-72% decrease of methanogenic rate was observed throughout the incubation at 7.00 g L(-1) of TAN compared to 0.26 g L(-1). Stable Isotope Probing analysis of active microbial communities in (13)C-acetate fed experiments coupled to automated ribosomal intergenic spacer analysis and 16S rDNA pyrotag sequencing confirmed that microbial communities were similar for both TAN conditions. At both TAN levels, the (13)C-labeled bacterial community was mainly affiliated to Clostridia-relatives, with OPB54 bacteria being the most abundant sequence in the heavy DNA 16S rDNA pyrotag library. Sequences closely related to Methanosarcina thermophila were also abundantly retrieved in the heavy DNA fractions, showing that this methanogen was still actively assimilating labeled carbon from acetate at free ammonia nitrogen concentrations up to 916 mg L(-1). Stable isotopic signature analysis of biogas, measured in unlabeled acetate fed experiments that were conducted in parallel, confirmed that acetoclastic methanogenic pathway was dominant at both ammonia concentrations. Our work demonstrates that, besides the syntrophic acetate oxidation pathway, acetoclastic methanogenesis catalyzed by Methanosarcina can also play a major role in methane production at high ammonia levels.

  1. Dopaminergic Circuitry Underlying Mating Drive.

    PubMed

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

    2016-07-01

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

  2. Distracted Driving Raises Crash Risk

    MedlinePlus

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

  3. Driving Speed vs Fuel Efficiency.

    ERIC Educational Resources Information Center

    Vest, Floyd

    1980-01-01

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

  4. Dangers of Texting While Driving

    MedlinePlus

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

  5. Warp drive with zero expansion

    NASA Astrophysics Data System (ADS)

    Natário, José

    2002-03-01

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

  6. Mechanical drive for blood pump

    DOEpatents

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

    1975-07-29

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

  7. Distracted driving: a neglected epidemic.

    PubMed

    Dildy, Dale W

    2012-10-01

    In 2009, the National Highway Traffic Safety Administration (NHTSA) estimated nearly 6,000 distracted driver fatalities and 515,000 injuries in the United States alone. Distracted driving is a worldwide problem that needs to be addressed. Software is available to disable cell phone usage while driving, but using the advanced technology may require legislation along with a renewed sense of driver responsibility. PMID:23061239

  8. Direct drive field actuator motors

    DOEpatents

    Grahn, A.R.

    1998-03-10

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

  9. Direct drive field actuator motors

    DOEpatents

    Grahn, Allen R.

    1998-01-01

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

  10. A drive for all users

    SciTech Connect

    Drury, W.; Satya, T.

    1995-12-31

    The forces of industrial automation and efficiency, both in terms of process capability and energy, continue to fuel the rapid growth in the market for electrical variable speed drives. This demand coupled with the need for improved performance and the inevitable consequence of growth, results in a fiercely competitive market place. Within such an environment the claim of ``A drive for all users`` is not new, and those with some knowledge of the drives industry will consider any such claim with great skepticism. The literature on drives is littered with industrialists, and more than a few academics, claiming to have the ultimate drive, the optimum for each and every application. This situation is particularly true in the case of AC drive technology. The documented battles between proponents of current source verses PWM voltage source, not to mention the quest for the ultimate PWM strategy, have resulted in substantial deforestation of the planet. This paper makes no such unqualified claim rather it describes a very substantial and significant step towards such a eutopia.

  11. Low backlash direct drive actuator

    DOEpatents

    Kuklo, T.C.

    1994-10-25

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

  12. Low backlash direct drive actuator

    DOEpatents

    Kuklo, Thomas C.

    1994-01-01

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

  13. China Continues to Drive Foreign-Student Growth in the United States

    ERIC Educational Resources Information Center

    McMurtrie, Beth

    2012-01-01

    This article discusses the results of the latest "Open Doors" report from the Institute of International Education. The report states that thousands of mainland Chinese students in pursuit of an American education helped drive up international enrollments at colleges across the United States. Double-digit growth from China, primarily at the…

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

    PubMed Central

    Rothman, Emily F.; Adhia, Avanti

    2015-01-01

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

  15. Decreased miR-195 Expression Protects Rats from Spinal Cord Injury Primarily by Targeting HIF-1α.

    PubMed

    Tao, Bo; Shi, Keqin

    2016-01-01

    Hypoxia-inducible factor 1-alpha (HIF-1α) protects hypoxic cells from apoptosis and necrosis under ischemic and anoxic conditions. miRNAs are important regulators in the genome. This study aims to explore whether miR-195 is involved in spinal cord injury through HIF-1α. A total of 40 male Sprague-Dawley (SD) rats were separated into four groups: Sham, Control, Ad-con, and Ad-miR-195. The behavior recovery was explored using the Basso, Beattie and Bresnahan (BBB) scoring system. Then, the rats were sacrificed, and the spinal cords were collected. The levels of the HIF-1α, Bcl-2, Bax and VEGF proteins were explored using western blotting. H&E and immunohistochemistry were applied to study the morphological changes. qPCR analysis revealed that miR-195 was significantly decreased after spinal cord injury (SCI). Meanwhile, the expression of Bcl-2, VEGF and HIF-1α was increased in animals after SCI. More importantly, administration with Ad-miR-195 significantly decreased the HIF-1α protein level, thereby reducing Bcl-2 and VEGF expression. In addition, Ad-miR-195 also obviously increased the number of apoptotic cells and decreased the neurological recovery in the animals injected with Ad-miR-195. In conclusion, reduced miR-195 expression partially protects rats from spinal cord injury, primarily by targeting HIF-1α. PMID:26927342

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

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

    PubMed

    Rothman, Emily F; Adhia, Avanti

    2015-01-01

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

  18. The period of the circadian oscillator is primarily determined by the balance between casein kinase 1 and protein phosphatase 1.

    PubMed

    Lee, Hyeong-min; Chen, Rongmin; Kim, Hyukmin; Etchegaray, Jean-Pierre; Weaver, David R; Lee, Choogon

    2011-09-27

    Mounting evidence suggests that PERIOD (PER) proteins play a central role in setting the speed (period) and phase of the circadian clock. Pharmacological and genetic studies have shown that changes in PER phosphorylation kinetics are associated with changes in circadian rhythm period and phase, which can lead to sleep disorders such as Familial Advanced Sleep Phase Syndrome in humans. We and others have shown that casein kinase 1δ and ε (CK1δ/ε) are essential PER kinases, but it is clear that additional, unknown mechanisms are also crucial for regulating the kinetics of PER phosphorylation. Here we report that circadian periodicity is determined primarily through PER phosphorylation kinetics set by the balance between CK1δ/ε and protein phosphatase 1 (PP1). In CK1δ/ε-deficient cells, PER phosphorylation is severely compromised and nonrhythmic, and the PER proteins are constitutively cytoplasmic. However, when PP1 is disrupted, PER phosphorylation is dramatically accelerated; the same effect is not seen when PP2A is disrupted. Our work demonstrates that the speed and rhythmicity of PER phosphorylation are controlled by the balance between CK1δ/ε and PP1, which in turn determines the period of the circadian oscillator. Thus, our findings provide clear insights into the molecular basis of how the period and phase of our daily rhythms are determined. PMID:21930935

  19. Dietary omega-3 fatty acids modulate the eicosanoid profile in man primarily via the CYP-epoxygenase pathway[S

    PubMed Central

    Fischer, Robert; Konkel, Anne; Mehling, Heidrun; Blossey, Katrin; Gapelyuk, Andrej; Wessel, Niels; von Schacky, Clemens; Dechend, Ralf; Muller, Dominik N.; Rothe, Michael; Luft, Friedrich C.; Weylandt, Karsten; Schunck, Wolf-Hagen

    2014-01-01

    Cytochrome P450 (CYP)-dependent metabolites of arachidonic acid (AA) contribute to the regulation of cardiovascular function. CYP enzymes also accept EPA and DHA to yield more potent vasodilatory and potentially anti-arrhythmic metabolites, suggesting that the endogenous CYP-eicosanoid profile can be favorably shifted by dietary omega-3 fatty acids. To test this hypothesis, 20 healthy volunteers were treated with an EPA/DHA supplement and analyzed for concomitant changes in the circulatory and urinary levels of AA-, EPA-, and DHA-derived metabolites produced by the cyclooxygenase-, lipoxygenase (LOX)-, and CYP-dependent pathways. Raising the Omega-3 Index from about four to eight primarily resulted in a large increase of EPA-derived CYP-dependent epoxy-metabolites followed by increases of EPA- and DHA-derived LOX-dependent monohydroxy-metabolites including the precursors of the resolvin E and D families; resolvins themselves were not detected. The metabolite/precursor fatty acid ratios indicated that CYP epoxygenases metabolized EPA with an 8.6-fold higher efficiency and DHA with a 2.2-fold higher efficiency than AA. Effects on leukotriene, prostaglandin E, prostacyclin, and thromboxane formation remained rather weak. We propose that CYP-dependent epoxy-metabolites of EPA and DHA may function as mediators of the vasodilatory and cardioprotective effects of omega-3 fatty acids and could serve as biomarkers in clinical studies investigating the cardiovascular effects of EPA/DHA supplementation. PMID:24634501

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

    PubMed

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

    2014-04-01

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

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

    PubMed

    Rothman, Emily F; Adhia, Avanti

    2015-12-23

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

  2. Affinity Maturation of a Potent Family of HIV Antibodies Is Primarily Focused on Accommodating or Avoiding Glycans.

    PubMed

    Garces, Fernando; Lee, Jeong Hyun; de Val, Natalia; de la Pena, Alba Torrents; Kong, Leopold; Puchades, Cristina; Hua, Yuanzi; Stanfield, Robyn L; Burton, Dennis R; Moore, John P; Sanders, Rogier W; Ward, Andrew B; Wilson, Ian A

    2015-12-15

    The high-mannose patch on the HIV-1 envelope (Env) glycoprotein is the epicenter for binding of the potent broadly neutralizing PGT121 family of antibodies, but strategies for generating such antibodies by vaccination have not been defined. We generated structures of inferred antibody intermediates by X-ray crystallography and electron microscopy to elucidate the molecular events that occurred during evolution of this family. Binding analyses revealed that affinity maturation was primarily focused on avoiding, accommodating, or binding the N137 glycan. The overall antibody approach angle to Env was defined very early in the maturation process, yet some variation evolved in the PGT121 family branches that led to differences in glycan specificities in their respective epitopes. Furthermore, we determined a crystal structure of the recombinant BG505 SOSIP.664 HIV-1 trimer with a PGT121 family member at 3.0 Å that, in concert with these antibody intermediate structures, provides insights to advance design of HIV vaccine candidates. PMID:26682982

  3. Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke.

    PubMed

    Borgerding, M F; Bodnar, J A; Chung, H L; Mangan, P P; Morrison, C C; Risner, C H; Rogers, J C; Simmons, D F; Uhrig, M S; Wendelboe, F N; Wingate, D E; Winkler, L S

    1998-07-01

    A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active.

  4. Chemical and biological studies of a new cigarette that primarily heats tobacco. Part 1. Chemical composition of mainstream smoke.

    PubMed

    Borgerding, M F; Bodnar, J A; Chung, H L; Mangan, P P; Morrison, C C; Risner, C H; Rogers, J C; Simmons, D F; Uhrig, M S; Wendelboe, F N; Wingate, D E; Winkler, L S

    1998-03-01

    A new-technology cigarette has been developed. While the new cigarette burns some tobacco, it does not use tobacco as the fuel to sustain combustion and provide heat to the cigarette. Rather, the new cigarette primarily heats tobacco thereby reducing products of smoke formation mechanisms such as tobacco combustion, tobacco pyrolysis and pyrosynthesis. The mainstream smoke composition from a cigarette based on the new design (TOB-HT) has been characterized in comparative chemical testing with two reference cigarettes using the FTC puffing regimen. Thermal properties, UV absorption characteristics, elemental composition and materials balance studies all suggest a simplified smoke aerosol. Twenty-five smoke constituents ("target compounds") identified by the scientific community as compounds that may contribute to the diseases statistically associated with smoking have also been measured. Mainstream smoke concentrations of most target compounds are significantly lower with the TOB-HT cigarette when compared with reference cigarettes in the ultra-light "tar" and light "tar" categories. Taken together, chemical analysis results suggest simplified TOB-HT smoke chemistry with marked reductions in specific chemicals reported to be biologically active.

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

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  6. The Reliability and Validity of Drug Users' Self Reports of Amphetamine Use Among Primarily Heroin and Cocaine Users

    PubMed Central

    Napper, Lucy E.; Fisher, Dennis G.; Johnson, Mark E.; Wood, Michele M.

    2009-01-01

    Relatively few studies have addressed the psychometric properties of self-report measures of amphetamine use. This study examines the reliability and validity of the Risk Behavior Assessment's (RBA) lifetime and recent amphetamine-use questions. To evaluate validity, 4027 out-of-treatment primarily cocaine and heroin users provided urine samples that were compared to self-report data; to evaluate reliability, 218 completed the RBA at two time points, 48 hours apart. In the overall sample, self-reports demonstrated moderately high validity, with a 95% accuracy rate (kappa =.54). When analysis was restricted to recent amphetamine users validity was slightly lower (71.5% accuracy; kappa = .41). Test-retest data indicated good reliability for self-reports of ever having used amphetamine (kappa =.79), and amphetamine use in the past 30 days (.75 < r < .91). Out-of-treatment drug users provided accurate self-reports of amphetamine use. Reliable and valid measures are essential for describing and predicting trends in amphetamine use, evaluating the effectiveness of interventions, and developing policies and programs. PMID:20053503

  7. Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique

    PubMed Central

    2015-01-01

    Efficient driving of piezoelectric materials is desirable when operating transducers for biomedical applications such as high intensity focused ultrasound (HIFU) or ultrasound imaging. More efficient operation reduces the electric power required to produce the desired bioeffect or contrast. Our preliminary work [Cole et al. Journal of Physics: Condensed Matter. 2014;26(13):135901.] suggested that driving transducers by applying orthogonal electric fields can significantly reduce the coercivity that opposes ferroelectric switching. We present here the experimental validation of this biaxial driving technique using piezoelectric ceramics typically used in HIFU. A set of narrow-band transducers was fabricated with two sets of electrodes placed in an orthogonal configuration (following the propagation and the lateral mode). The geometry of the ceramic was chosen to have a resonance frequency similar for the propagation and the lateral mode. The average (± s.d.) resonance frequency of the samples was 465.1 (± 1.5) kHz. Experiments were conducted in which each pair of electrodes was driven independently and measurements of effective acoustic power were obtained using the radiation force method. The efficiency (acoustic/electric power) of the biaxial driving method was compared to the results obtained when driving the ceramic using electrodes placed only in the pole direction. Our results indicate that the biaxial method increases efficiency from 50% to 125% relative to the using a single electric field. PMID:26418550

  8. Efficient Driving of Piezoelectric Transducers Using a Biaxial Driving Technique.

    PubMed

    Pichardo, Samuel; Silva, Rafael R C; Rubel, Oleg; Curiel, Laura

    2015-01-01

    Efficient driving of piezoelectric materials is desirable when operating transducers for biomedical applications such as high intensity focused ultrasound (HIFU) or ultrasound imaging. More efficient operation reduces the electric power required to produce the desired bioeffect or contrast. Our preliminary work [Cole et al. Journal of Physics: Condensed Matter. 2014;26(13):135901.] suggested that driving transducers by applying orthogonal electric fields can significantly reduce the coercivity that opposes ferroelectric switching. We present here the experimental validation of this biaxial driving technique using piezoelectric ceramics typically used in HIFU. A set of narrow-band transducers was fabricated with two sets of electrodes placed in an orthogonal configuration (following the propagation and the lateral mode). The geometry of the ceramic was chosen to have a resonance frequency similar for the propagation and the lateral mode. The average (± s.d.) resonance frequency of the samples was 465.1 (± 1.5) kHz. Experiments were conducted in which each pair of electrodes was driven independently and measurements of effective acoustic power were obtained using the radiation force method. The efficiency (acoustic/electric power) of the biaxial driving method was compared to the results obtained when driving the ceramic using electrodes placed only in the pole direction. Our results indicate that the biaxial method increases efficiency from 50% to 125% relative to the using a single electric field.

  9. Vascular Endothelial Growth Factor Acts Primarily via Platelet-Derived Growth Factor Receptor α to Promote Proliferative Vitreoretinopathy

    PubMed Central

    Pennock, Steven; Haddock, Luis J.; Mukai, Shizuo; Kazlauskas, Andrius

    2015-01-01

    Proliferative vitreoretinopathy (PVR) is a nonneovascular blinding disease and the leading cause for failure in surgical repair of rhegmatogenous retinal detachments. Once formed, PVR is difficult to treat. Hence, there is an acute interest in developing approaches to prevent PVR. Of the many growth factors and cytokines that accumulate in vitreous as PVR develops, neutralizing vascular endothelial growth factor (VEGF) A has recently been found to prevent PVR in at least one animal model. The goal of this study was to test if Food and Drug Administration–approved agents could protect the eye from PVR in multiple animal models and to further investigate the underlying mechanisms. Neutralizing VEGF with aflibercept (VEGF Trap-Eye) safely and effectively protected rabbits from PVR in multiple models of disease. Furthermore, aflibercept reduced the bioactivity of both experimental and clinical PVR vitreous. Finally, although VEGF could promote some PVR-associated cellular responses via VEGF receptors expressed on the retinal pigment epithelial cells that drive this disease, VEGF's major contribution to vitreal bioactivity occurred via platelet-derived growth factor receptor α. Thus, VEGF promotes PVR by a noncanonical ability to engage platelet-derived growth factor receptor α. These findings indicate that VEGF contributes to nonangiogenic diseases and that anti–VEGF-based therapies may be effective on a wider spectrum of diseases than previously appreciated. PMID:25261788

  10. Half-century evidence from western Canada shows forest dynamics are primarily driven by competition followed by climate

    PubMed Central

    Zhang, Jian; Huang, Shongming; He, Fangliang

    2015-01-01

    Tree mortality, growth, and recruitment are essential components of forest dynamics and resiliency, for which there is great concern as climate change progresses at high latitudes. Tree mortality has been observed to increase over the past decades in many regions, but the causes of this increase are not well understood, and we know even less about long-term changes in growth and recruitment rates. Using a dataset of long-term (1958–2009) observations on 1,680 permanent sample plots from undisturbed natural forests in western Canada, we found that tree demographic rates have changed markedly over the last five decades. We observed a widespread, significant increase in tree mortality, a significant decrease in tree growth, and a similar but weaker trend of decreasing recruitment. However, these changes varied widely across tree size, forest age, ecozones, and species. We found that competition was the primary factor causing the long-term changes in tree mortality, growth, and recruitment. Regional climate had a weaker yet still significant effect on tree mortality, but little effect on tree growth and recruitment. This finding suggests that internal community-level processes—more so than external climatic factors—are driving forest dynamics. PMID:25775576

  11. Half-century evidence from western Canada shows forest dynamics are primarily driven by competition followed by climate.

    PubMed

    Zhang, Jian; Huang, Shongming; He, Fangliang

    2015-03-31

    Tree mortality, growth, and recruitment are essential components of forest dynamics and resiliency, for which there is great concern as climate change progresses at high latitudes. Tree mortality has been observed to increase over the past decades in many regions, but the causes of this increase are not well understood, and we know even less about long-term changes in growth and recruitment rates. Using a dataset of long-term (1958-2009) observations on 1,680 permanent sample plots from undisturbed natural forests in western Canada, we found that tree demographic rates have changed markedly over the last five decades. We observed a widespread, significant increase in tree mortality, a significant decrease in tree growth, and a similar but weaker trend of decreasing recruitment. However, these changes varied widely across tree size, forest age, ecozones, and species. We found that competition was the primary factor causing the long-term changes in tree mortality, growth, and recruitment. Regional climate had a weaker yet still significant effect on tree mortality, but little effect on tree growth and recruitment. This finding suggests that internal community-level processes-more so than external climatic factors-are driving forest dynamics.

  12. Dynamically correlated mutations drive human Influenza A evolution.

    PubMed

    Tria, F; Pompei, S; Loreto, V

    2013-01-01

    Human Influenza A virus undergoes recurrent changes in the hemagglutinin (HA) surface protein, primarily involved in the human antibody recognition. Relevant antigenic changes, enabling the virus to evade host immune response, have been recognized to occur in parallel to multiple mutations at antigenic sites in HA. Yet, the role of correlated mutations (epistasis) in driving the molecular evolution of the virus still represents a challenging puzzle. Further, though circulation at a global geographic level is key for the survival of Influenza A, its role in shaping the viral phylodynamics remains largely unexplored. Here we show, through a sequence based epidemiological model, that epistatic effects between amino acids substitutions, coupled with a reservoir that mimics worldwide circulating viruses, are key determinants that drive human Influenza A evolution. Our approach explains all the up-to-date observations characterizing the evolution of H3N2 subtype, including phylogenetic properties, nucleotide fixation patterns, and composition of antigenic clusters.

  13. i3Drive, a 3D interactive driving simulator.

    PubMed

    Ambroz, Miha; Prebil, Ivan

    2010-01-01

    i3Drive, a wheeled-vehicle simulator, can accurately simulate vehicles of various configurations with up to eight wheels in real time on a desktop PC. It presents the vehicle dynamics as an interactive animation in a virtual 3D environment. The application is fully GUI-controlled, giving users an easy overview of the simulation parameters and letting them adjust those parameters interactively. It models all relevant vehicle systems, including the mechanical models of the suspension, power train, and braking and steering systems. The simulation results generally correspond well with actual measurements, making the system useful for studying vehicle performance in various driving scenarios. i3Drive is thus a worthy complement to other, more complex tools for vehicle-dynamics simulation and analysis.

  14. FRONTOTEMPORAL AND DOPAMINERGIC CONTROL OF IDEA GENERATION AND CREATIVE DRIVE

    PubMed Central

    Flaherty, Alice W.

    2008-01-01

    This paper presents a three-factor anatomical model of human idea generation and creative drive, focusing on interactions between the temporal lobes, frontal lobes, and limbic system. Evidence is drawn from functional imaging, drug studies, and lesion analysis. Temporal lobe changes, as in hypergraphia, often increase idea generation, sometimes at the expense of quality. Frontal lobe deficits may decrease idea generation, in part because of rigid judgments about an idea's worth. These phenomena are clearest in verbal creativity, and roughly parallel the pressured communication of temporal lobe epilepsy, mania, and Wernicke's aphasia--compared to the sparse speech and cognitive inflexibility of depression, Broca's aphasia, and other frontal lobe lesions. The phenomena also shape non-linguistic creativity, as in that of frontotemporal dementia. The appropriate balance between frontal and temporal activity is mediated by mutually inhibitory corticocortical interactions. Mesolimbic dopamine influences novelty seeking and creative drive. Dopamine agonists and antagonists have opposite effects on goal-directed behavior and hallucinations. Creative drive is not identical to skill—the latter depends more on neocortical association areas. However, drive correlates better with successful creative output than skill does. Traditional neuroscientific models of creativity, such as the left brain – right brain hemispheric model, emphasize skills primarily, and stress art and musical skill at the expense of language and mathematics. The three-factor model proposed here predicts findings in a broad range of normal and pathological states, and can be tested in many experimental paradigms. PMID:16254989

  15. Y-Chromosomal Diversity in Europe Is Clinal and Influenced Primarily by Geography, Rather than by Language

    PubMed Central

    Rosser, Zoë H.; Zerjal, Tatiana; Hurles, Matthew E.; Adojaan, Maarja; Alavantic, Dragan; Amorim, António; Amos, William; Armenteros, Manuel; Arroyo, Eduardo; Barbujani, Guido; Beckman, Gunhild; Beckman, Lars; Bertranpetit, Jaume; Bosch, Elena; Bradley, Daniel G.; Brede, Gaute; Cooper, Gillian; Côrte-Real, Helena B. S. M.; de Knijff, Peter; Decorte, Ronny; Dubrova, Yuri E.; Evgrafov, Oleg; Gilissen, Anja; Glisic, Sanja; Gölge, Mukaddes; Hill, Emmeline W.; Jeziorowska, Anna; Kalaydjieva, Luba; Kayser, Manfred; Kivisild, Toomas; Kravchenko, Sergey A.; Krumina, Astrida; Kučinskas, Vaidutis; Lavinha, João; Livshits, Ludmila A.; Malaspina, Patrizia; Maria, Syrrou; McElreavey, Ken; Meitinger, Thomas A.; Mikelsaar, Aavo-Valdur; Mitchell, R. John; Nafa, Khedoudja; Nicholson, Jayne; Nørby, Søren; Pandya, Arpita; Parik, Jüri; Patsalis, Philippos C.; Pereira, Luísa; Peterlin, Borut; Pielberg, Gerli; Prata, Maria João; Previderé, Carlo; Roewer, Lutz; Rootsi, Siiri; Rubinsztein, D. C.; Saillard, Juliette; Santos, Fabrício R.; Stefanescu, Gheorghe; Sykes, Bryan C.; Tolun, Aslihan; Villems, Richard; Tyler-Smith, Chris; Jobling, Mark A.

    2000-01-01

    Clinal patterns of autosomal genetic diversity within Europe have been interpreted in previous studies in terms of a Neolithic demic diffusion model for the spread of agriculture; in contrast, studies using mtDNA have traced many founding lineages to the Paleolithic and have not shown strongly clinal variation. We have used 11 human Y-chromosomal biallelic polymorphisms, defining 10 haplogroups, to analyze a sample of 3,616 Y chromosomes belonging to 47 European and circum-European populations. Patterns of geographic differentiation are highly nonrandom, and, when they are assessed using spatial autocorrelation analysis, they show significant clines for five of six haplogroups analyzed. Clines for two haplogroups, representing 45% of the chromosomes, are continentwide and consistent with the demic diffusion hypothesis. Clines for three other haplogroups each have different foci and are more regionally restricted and are likely to reflect distinct population movements, including one from north of the Black Sea. Principal-components analysis suggests that populations are related primarily on the basis of geography, rather than on the basis of linguistic affinity. This is confirmed in Mantel tests, which show a strong and highly significant partial correlation between genetics and geography but a low, nonsignificant partial correlation between genetics and language. Genetic-barrier analysis also indicates the primacy of geography in the shaping of patterns of variation. These patterns retain a strong signal of expansion from the Near East but also suggest that the demographic history of Europe has been complex and influenced by other major population movements, as well as by linguistic and geographic heterogeneities and the effects of drift. PMID:11078479

  16. Ah receptor mediated suppression of the antibody response in mice is primarily dependent on the Ah phenotype of lymphoid tissue.

    PubMed

    Silkworth, J B; Antrim, L A; Sack, G

    1986-12-01

    Halogenated aromatic hydrocarbons act through the aromatic hydrocarbon (Ah) receptor in mice to produce a series of toxic effects of the immune system. The receptor protein is a product of the Ah gene locus. Ah responsive (Ahb/Ahb) mice express a high affinity receptor in both lymphoid and nonlymphoid tissues whereas nonresponsive Ahd/Ahd mice express a poor affinity receptor. To determine the role of the Ah receptor of lymphoid tissue relative to that of nonlymphoid tissue in the induction of immune impairment, bone marrow was used to reconstitute lethally irradiated mice of the same or opposite Ah phenotype. All mice were given 3,3',4,4'-tetrachlorobiphenyl (35 and 350 mumol/kg) ip 2 days before immunization with sheep erythrocytes (SRBC). The immune response to this T dependent antigen and organ weights were determined 5 or 7 days later in normal or chimeric mice, respectively. Monoclonal Lyt 1.1 and Lyt 1.2 antibodies were used to establish the origin of the cells which repopulated the chimeric thymuses. The immune responses of both BALB/cBy (Ahb/Ahb) and the BALB/cBy X DBA/2 hybrid, CByD2F1 (Ahb/Ahd), were significantly suppressed but DBA/2 mice were unaffected. The immune responses of chimeric BALB/cBy----BALB/cBy and BALB/cBy----DBA/2 (donor----recipient) mice were also significantly suppressed and thymic atrophy was observed in both cases. The serum anti-SRBC antibody titers of DBA/2----BALB/cBy chimeras were also significantly decreased although not to the same extent as in BALB/cBy----DBA/2 mice. Chimeric DBA/2----DBA/2 mice were not affected. These results indicate that the sensitivity to Ah receptor mediated suppression of the antibody response is primarily determined by the Ah phenotype of the lymphoid tissue.

  17. Both cell substratum regulation and hormonal regulation of milk protein gene expression are exerted primarily at the posttranscriptional level

    SciTech Connect

    Eisenstein, R.S.; Rosen, J.M.

    1988-08-01

    The mechanism by which individual peptide and steroid hormones and cell-substratum interactions regulate milk protein gene expression has been studied in the COMMA-D mammary epithelial cell line. In the presence of insulin, hydrocortisone, and prolactin, growth of COMMA-D cells on floating collagen gels in comparison with that on a plastic substratum resulted in a 2.5- to 3-fold increase in the relative rate of ..beta..-casein gene transcription but a 37-fold increase in ..beta..-casein mRNA accumulation. In contrast, whey acidic protein gene transcription was constitutive in COMMA-D cells grown on either substratum, but its mRNA was unstable and little intact mature mRNA was detected. Culturing COMMA-D cells on collagen also promoted increased expression of other genes expressed in differentiated mammary epithelial cells, including those encoding ..cap alpha..- and ..gamma..-casein, transferrin, malic enzyme, and phosphoenolpyruvate carboxykinase but decreased the expression of actin and histone genes. Using COMMA-D cells, the authors defined further the role of individual hormones in influencing ..beta..-casein gene transcription. With insulin alone, a basal level of ..beta..-casein gene transcription was detected in COMMA-D cells grown on floating collagen gels. Addition of prolactin but not hydrocortisone resulted in a 2.5- to 3.0-fold increase in ..beta..-casein gene transcription, but both hormones were required to elicit the maximal 73-fold induction in mRNA accumulation. The posttranscriptional effect of hormones on casein mRNA accummulation preceded any detectable changes in the relative rate of transcription. Thus, regulation by both hormones and cell substratum of casein gene expression is exerted primarily at the post transcriptional level.

  18. Alpha power and coherence primarily reflect neural activity related to stages of motor response during a continuous monitoring task.

    PubMed

    Moore, Roger A; Gale, Anthony; Morris, Paul H; Forrester, Dave

    2008-08-01

    Previously, EEG theta (4-6 Hz) was related to goal conflict resolution [Moore, R.A., Gale, A., Morris, P.H., Forrester, D., 2006. Theta phase locking across the neocortex reflects cortico-hippocampal recursive communication during goal conflict resolution. Int. J. Psychophysiol. 60, 260-273] in the context of theory linked with animal hippocampal theta [Gray, J.A., McNaughton, N., 2000. The Neuropsychology of Anxiety: An Enquiry into the Functions of the Septo-Hippocampal system, 2nd ed, Oxford University Press, Oxford]. Here, the hypothesis that human EEG alpha (8-12 Hz) may also be a natural analogue to animal hippocampal theta is tested. Participants engaged in a monitoring task where the object was to press a response key immediately after presentation of 4 individual, non-repeating, single integer odd digits. These were presented amongst a continuous stream of single integer digits and Xs. EEG recorded in the earlier study were reanalysed; this time extracting alpha power and coherence from the same 34 participants. Alpha had a different profile to theta and was not primarily related to goal conflict. Low alpha (8-10 Hz) coherence consistently increased at electrodes close to primary sensorimotor cortex; particularly during response execution and response inhibition. The coherence analysis revealed that high alpha (10-12 Hz) related to response execution. Supplementary analyses demonstrated widespread high alpha coherence increase during response execution, inhibition and preparation. These data were discussed within the context of motor driven 'classic alpha' and Rolandic mu. A coherence profile which differentiated response execution and response inhibition was proposed to reflect a working memory network which was activated during response execution. Also, alpha power (8-12 Hz) reduced at several central electrodes during response execution. This reflected classic Rolandic mu response. Participants displaying a predicted low alpha power trend had the

  19. Predator effects on a detritus-based food web are primarily mediated by non-trophic interactions.

    PubMed

    Majdi, Nabil; Boiché, Anatole; Traunspurger, Walter; Lecerf, Antoine

    2014-07-01

    Predator effects on ecosystems can extend far beyond their prey and are often not solely lethally transmitted. Change in prey traits in response to predation risk can have important repercussions on community assembly and key ecosystem processes (i.e. trait-mediated indirect effects). In addition, some predators themselves alter habitat structure or nutrient cycling through ecological engineering effects. Tracking these non-trophic pathways is thus an important, yet challenging task to gain a better grasp of the functional role of predators. Multiple lines of evidence suggest that, in detritus-based food webs, non-trophic interactions may prevail over purely trophic interactions in determining predator effects on plant litter decomposition. This hypothesis was tested in a headwater stream by modulating the density of a flatworm predator (Polycelis felina) in enclosures containing oak (Quercus robur) leaf litter exposed to natural colonization by small invertebrates and microbial decomposers. Causal path modelling was used to infer how predator effects propagated through the food web. Flatworms accelerated litter decomposition through positive effects on microbial decomposers. The biomass of prey and non-prey invertebrates was not negatively affected by flatworms, suggesting that net predator effect on litter decomposition was primarily determined by non-trophic interactions. Flatworms enhanced the deposition and retention of fine sediments on leaf surface, thereby improving leaf colonization by invertebrates - most of which having strong affinities with interstitial habitats. This predator-induced improvement of habitat availability was attributed to the sticky nature of the mucus that flatworms secrete in copious amount while foraging. Results of path analyses further indicated that this bottom-up ecological engineering effect was as powerful as the top-down effect on invertebrate prey. Our findings suggest that predators have the potential to affect substantially

  20. A Genome-Wide Survey of Imprinted Genes in Rice Seeds Reveals Imprinting Primarily Occurs in the Endosperm

    PubMed Central

    Luo, Ming; Taylor, Jennifer M.; Spriggs, Andrew; Zhang, Hongyu; Wu, Xianjun; Russell, Scott; Singh, Mohan; Koltunow, Anna

    2011-01-01

    Genomic imprinting causes the expression of an allele depending on its parental origin. In plants, most imprinted genes have been identified in Arabidopsis endosperm, a transient structure consumed by the embryo during seed formation. We identified imprinted genes in rice seed where both the endosperm and embryo are present at seed maturity. RNA was extracted from embryos and endosperm of seeds obtained from reciprocal crosses between two subspecies Nipponbare (Japonica rice) and 93-11 (Indica rice). Sequenced reads from cDNA libraries were aligned to their respective parental genomes using single-nucleotide polymorphisms (SNPs). Reads across SNPs enabled derivation of parental expression bias ratios. A continuum of parental expression bias states was observed. Statistical analyses indicated 262 candidate imprinted loci in the endosperm and three in the embryo (168 genic and 97 non-genic). Fifty-six of the 67 loci investigated were confirmed to be imprinted in the seed. Imprinted loci are not clustered in the rice genome as found in mammals. All of these imprinted loci were expressed in the endosperm, and one of these was also imprinted in the embryo, confirming that in both rice and Arabidopsis imprinted expression is primarily confined to the endosperm. Some rice imprinted genes were also expressed in vegetative tissues, indicating that they have additional roles in plant growth. Comparison of candidate imprinted genes found in rice with imprinted candidate loci obtained from genome-wide surveys of imprinted genes in Arabidopsis to date shows a low degree of conservation, suggesting that imprinting has evolved independently in eudicots and monocots. PMID:21731498

  1. Maize Centromere Structure and Evolution: Sequence Analysis of Centromeres 2 and 5 Reveals Dynamic Loci Shaped Primarily by Retrotransposons

    PubMed Central

    Albert, Patrice S.; Koo, Dal-Hoe; Shi, Jinghua; Gao, Zhi; Han, Fangpu; Lee, Hyeran; Xu, Ronghui; Allison, Jamie; Birchler, James A.; Jiang, Jiming; Dawe, R. Kelly; Presting, Gernot G.

    2009-01-01

    We describe a comprehensive and general approach for mapping centromeres and present a detailed characterization of two maize centromeres. Centromeres are difficult to map and analyze because they consist primarily of repetitive DNA sequences, which in maize are the tandem satellite repeat CentC and interspersed centromeric retrotransposons of maize (CRM). Centromeres are defined epigenetically by the centromeric histone H3 variant, CENH3. Using novel markers derived from centromere repeats, we have mapped all ten centromeres onto the physical and genetic maps of maize. We were able to completely traverse centromeres 2 and 5, confirm physical maps by fluorescence in situ hybridization (FISH), and delineate their functional regions by chromatin immunoprecipitation (ChIP) with anti-CENH3 antibody followed by pyrosequencing. These two centromeres differ substantially in size, apparent CENH3 density, and arrangement of centromeric repeats; and they are larger than the rice centromeres characterized to date. Furthermore, centromere 5 consists of two distinct CENH3 domains that are separated by several megabases. Succession of centromere repeat classes is evidenced by the fact that elements belonging to the recently active recombinant subgroups of CRM1 colonize the present day centromeres, while elements of the ancestral subgroups are also found in the flanking regions. Using abundant CRM and non-CRM retrotransposons that inserted in and near these two centromeres to create a historical record of centromere location, we show that maize centromeres are fluid genomic regions whose borders are heavily influenced by the interplay of retrotransposons and epigenetic marks. Furthermore, we propose that CRMs may be involved in removal of centromeric DNA (specifically CentC), invasion of centromeres by non-CRM retrotransposons, and local repositioning of the CENH3. PMID:19956743

  2. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Buses (OTRBs) § 37.195 Purchase or lease of OTRBs by private entities not primarily in the business of... are not primarily engaged in the business of transporting people, with respect to buses delivered to them on or after the date on which this subpart begins to apply to them. (a) Fixed-route systems....

  3. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Buses (OTRBs) § 37.195 Purchase or lease of OTRBs by private entities not primarily in the business of... are not primarily engaged in the business of transporting people, with respect to buses delivered to... required to purchase or lease an accessible bus except as needed to meet the requirements of § 37.189....

  4. 49 CFR 37.195 - Purchase or lease of OTRBs by private entities not primarily in the business of transporting people.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Buses (OTRBs) § 37.195 Purchase or lease of OTRBs by private entities not primarily in the business of... are not primarily engaged in the business of transporting people, with respect to buses delivered to... required to purchase or lease an accessible bus except as needed to meet the requirements of § 37.189....

  5. The chemical biology of methanogenesis

    NASA Astrophysics Data System (ADS)

    Ferry, James G.

    2010-12-01

    Two distinct pathways account for most of the CH 4 produced in the majority of the diverse and vast anaerobic environments of Earth's biosphere by microbes that are classified in the Archaea domain of life: conversion of the methyl group of acetate to CH 4 in the aceticlastic pathway and reduction of CO 2 with electrons derived from H 2, formate or CO in the CO 2 reduction pathway. Minor, albeit ecologically important, amounts of CH 4 are produced by conversion of methylotrophic substrates methanol, methylamines and methyl sulfides. Although all pathways have terminal steps in common, they deviate in the initial steps leading to CH 4 and mechanisms for synthesizing ATP for growth. Hydrogen gas is the major reductant for CO 2-reducing methanogens in the deep subsurface, although H 2 is also utilized by CO 2-reducing microbes from the Bacteria domain that produce acetate for the aceticlastic methanogens. This review presents fundamentals of the two major CH 4-producing pathways with a focus on understanding the potential for biologically-produced CH 4 on Mars.

  6. Drive: Theory and Construct Validation.

    PubMed

    Siegling, Alex B; Petrides, K V

    2016-01-01

    This article explicates the theory of drive and describes the development and validation of two measures. A representative set of drive facets was derived from an extensive corpus of human attributes (Study 1). Operationalised using an International Personality Item Pool version (the Drive:IPIP), a three-factor model was extracted from the facets in two samples and confirmed on a third sample (Study 2). The multi-item IPIP measure showed congruence with a short form, based on single-item ratings of the facets, and both demonstrated cross-informant reliability. Evidence also supported the measures' convergent, discriminant, concurrent, and incremental validity (Study 3). Based on very promising findings, the authors hope to initiate a stream of research in what is argued to be a rather neglected niche of individual differences and non-cognitive assessment. PMID:27409773

  7. Drive: Theory and Construct Validation

    PubMed Central

    Petrides, K. V.

    2016-01-01

    This article explicates the theory of drive and describes the development and validation of two measures. A representative set of drive facets was derived from an extensive corpus of human attributes (Study 1). Operationalised using an International Personality Item Pool version (the Drive:IPIP), a three-factor model was extracted from the facets in two samples and confirmed on a third sample (Study 2). The multi-item IPIP measure showed congruence with a short form, based on single-item ratings of the facets, and both demonstrated cross-informant reliability. Evidence also supported the measures’ convergent, discriminant, concurrent, and incremental validity (Study 3). Based on very promising findings, the authors hope to initiate a stream of research in what is argued to be a rather neglected niche of individual differences and non-cognitive assessment. PMID:27409773

  8. Drive: Theory and Construct Validation.

    PubMed

    Siegling, Alex B; Petrides, K V

    2016-01-01

    This article explicates the theory of drive and describes the development and validation of two measures. A representative set of drive facets was derived from an extensive corpus of human attributes (Study 1). Operationalised using an International Personality Item Pool version (the Drive:IPIP), a three-factor model was extracted from the facets in two samples and confirmed on a third sample (Study 2). The multi-item IPIP measure showed congruence with a short form, based on single-item ratings of the facets, and both demonstrated cross-informant reliability. Evidence also supported the measures' convergent, discriminant, concurrent, and incremental validity (Study 3). Based on very promising findings, the authors hope to initiate a stream of research in what is argued to be a rather neglected niche of individual differences and non-cognitive assessment.

  9. MULTIPLE DIFFERENTIAL ROTARY MECHANICAL DRIVE

    DOEpatents

    Smits, R.G.

    1964-01-28

    This patent relates to a mechanism suitable for such applications as driving two spaced-apart spools which carry a roll film strip under conditions where the film movement must be rapidly started, stopped, and reversed while maintaining a constant tension on the film. The basic drive is provided by a variable speed, reversible rnotor coupled to both spools through a first differential mechanism and driving both spools in the same direction. A second motor, providing a constant torque, is connected to the two spools through a second differential mechanism and is coupled to impart torque to one spool in a first direction anid to the other spool in the reverse direction thus applying a constant tension to the film passing over the two spools irrespective of the speed or direction of rotation thereof. (AEC)

  10. Rover Takes a Sunday Drive

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This animation, made with images from the Mars Exploration Rover Spirit hazard-identification camera, shows the rover's perspective of its first post-egress drive on Mars Sunday. Engineers drove Spirit approximately 3 meters (10 feet) toward its first rock target, a football-sized, mountain-shaped rock called Adirondack. The drive took approximately 30 minutes to complete, including time stopped to take images. Spirit first made a series of arcing turns totaling approximately 1 meter (3 feet). It then turned in place and made a series of short, straightforward movements totaling approximately 2 meters (6.5 feet).

  11. Driving and Age-Related Macular Degeneration

    ERIC Educational Resources Information Center

    Owsley, Cynthia; McGwin, Gerald, Jr.

    2008-01-01

    This article reviews the research literature on driving and age-related macular degeneration, which is motivated by the link between driving and the quality of life of older adults and their increased collision rate. It addresses the risk of crashes, driving performance, driving difficulty, self-regulation, and interventions to enhance, safety,…

  12. 32 CFR 634.43 - Driving records.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Driving records. 634.43 Section 634.43 National... INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Records and the Traffic Point System § 634.43 Driving... suspension or revocation actions. Table 5-1 of Part 634 Suspension/Revocation of Driving Privileges...

  13. 32 CFR 634.43 - Driving records.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Driving records. 634.43 Section 634.43 National... INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Records and the Traffic Point System § 634.43 Driving... suspension or revocation actions. Table 5-1 of Part 634 Suspension/Revocation of Driving Privileges...

  14. 32 CFR 634.43 - Driving records.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Driving records. 634.43 Section 634.43 National... INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Records and the Traffic Point System § 634.43 Driving... suspension or revocation actions. Table 5-1 of Part 634 Suspension/Revocation of Driving Privileges...

  15. 32 CFR 634.43 - Driving records.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Driving records. 634.43 Section 634.43 National... INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Records and the Traffic Point System § 634.43 Driving... suspension or revocation actions. Table 5-1 of Part 634 Suspension/Revocation of Driving Privileges...

  16. 32 CFR 634.43 - Driving records.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Driving records. 634.43 Section 634.43 National... INVESTIGATIONS MOTOR VEHICLE TRAFFIC SUPERVISION Driving Records and the Traffic Point System § 634.43 Driving... suspension or revocation actions. Table 5-1 of Part 634 Suspension/Revocation of Driving Privileges...

  17. Unsafe driving behaviour and four wheel drive vehicles: observational study

    PubMed Central

    Walker, Lesley; Williams, Jonathan; Jamrozik, Konrad

    2006-01-01

    Objective To assess the level of compliance with the new law in the United Kingdom mandating penalties for using a hand held mobile phone while driving, to compare compliance with this law with the one on the use of seat belts, and to compare compliance with these laws between drivers of four wheel drive vehicles and drivers of normal cars. Design Observational study with two phases—one within the “grace” period, the other starting one week after penalties were imposed on drivers using such telephones. Setting Three busy sites in London. Participants Drivers of 38 182 normal cars and 2944 four wheel drive vehicles. Main outcome measures Proportions of drivers seen to be using hand held mobile phones and not using seat belts. Results Drivers of four wheel drive vehicles were more likely than drivers of other cars to be seen using hand held mobile phones (8.2% v 2.0%) and not complying with the law on seat belts (19.5% v 15.0%). Levels of non-compliance with both laws were slightly higher in the penalty phase of observation, and breaking one law was associated with increased likelihood of breaking the other. Conclusions The level of non-compliance with the law on the use of hand held mobile phones by drivers in London is high, as is non-compliance with the law on seat belts. Drivers of four wheel drive vehicles were four times more likely than drivers of other cars to be seen using hand held mobile phones and slightly more likely not to comply with the law on seat belts. PMID:16798755

  18. Electronic 4-wheel drive control device

    NASA Technical Reports Server (NTRS)

    Hayato, S.; Takanori, S.; Shigeru, H.; Tatsunori, S.

    1984-01-01

    The internal rotation torque generated during operation of a 4-wheel drive vehicle is reduced using a control device whose clutch is attached to one part of the rear-wheel drive shaft. One torque sensor senses the drive torque associated with the rear wheel drive shaft. A second sensor senses the drive torque associated with the front wheel drive shaft. Revolution count sensors sense the revolutions of each drive shaft. By means of a microcomputer, the engagement of the clutch is changed to insure that the ratio of the torque sensors remains constant.

  19. Drive reconfiguration mechanism for tracked robotic vehicle

    DOEpatents

    Willis, W. David

    2000-01-01

    Drive reconfiguration apparatus for changing the configuration of a drive unit with respect to a vehicle body may comprise a guide system associated with the vehicle body and the drive unit which allows the drive unit to rotate about a center of rotation that is located at about a point where the drive unit contacts the surface being traversed. An actuator mounted to the vehicle body and connected to the drive unit rotates the drive unit about the center of rotation between a first position and a second position.

  20. Torque-Splitting Gear Drive

    NASA Technical Reports Server (NTRS)

    Kish, J.

    1991-01-01

    Geared drive train transmits torque from input shaft in equal parts along two paths in parallel, then combines torques in single output shaft. Scheme reduces load on teeth of meshing gears while furnishing redundancy to protect against failures. Such splitting and recombination of torques common in design of turbine engines.

  1. Hydromechanical transmission with hydrodynamic drive

    DOEpatents

    Orshansky, Jr., deceased, Elias; Weseloh, William E.

    1979-01-01

    This transmission has a first planetary gear assembly having first input means connected to an input shaft, first output means, and first reaction means, and a second planetary gear assembly having second input means connected to the first input means, second output means, and second reaction means connected directly to the first reaction means by a reaction shaft. First clutch means, when engaged, connect the first output means to an output shaft in a high driving range. A hydrodynamic drive is used; for example, a torque converter, which may or may not have a stationary case, has a pump connected to the second output means, a stator grounded by an overrunning clutch to the case, and a turbine connected to an output member, and may be used in a starting phase. Alternatively, a fluid coupling or other type of hydrodynamic drive may be used. Second clutch means, when engaged, for connecting the output member to the output shaft in a low driving range. A variable-displacement hydraulic unit is mechanically connected to the input shaft, and a fixed-displacement hydraulic unit is mechanically connected to the reaction shaft. The hydraulic units are hydraulically connected together so that when one operates as a pump the other acts as a motor, and vice versa. Both clutch means are connected to the output shaft through a forward-reverse shift arrangement. It is possible to lock out the torque converter after the starting phase is over.

  2. Promising Electric Aircraft Drive Systems

    NASA Technical Reports Server (NTRS)

    Dudley, Michael R.

    2010-01-01

    An overview of electric aircraft propulsion technology performance thresholds for key power system components is presented. A weight comparison of electric drive systems with equivalent total delivered energy is made to help identify component performance requirements, and promising research and development opportunities.

  3. Driving Competencies for the Elderly.

    ERIC Educational Resources Information Center

    New York State Education Dept., Albany. Bureau of Continuing Education Curriculum Development.

    Designed for use by directors of senior citizen groups, continuing education directors, and driver education instructors, this manual suggests a course outline, subject content, and instructional materials for effectively teaching a refresher driving course. The first seven topics represent the basic content and none should be omitted: orientation…

  4. Virtual Rewards for Driving Green

    ERIC Educational Resources Information Center

    Pritchard, Josh

    2010-01-01

    Carbon dioxide from automobiles is a major contributor to global climate change. In "Virtual Rewards for Driving Green," Josh Pritchard proposes a computer application that will enable fuel-efficient drivers to earn "green" dollars with which to buy digital merchandise on the Web. Can getting items that exist only in cyberspace actually change a…

  5. Older people drive political agenda.

    PubMed

    2001-07-01

    So, as the Labour party storms home on the back of another massive majority, hold on to your seats for more thrills, spills and radical reforms as the government gets on with the business of building an inclusive society, eradicating poverty and driving on the revolution to the beat of the private sector drum. PMID:27321254

  6. Test-Driving Their Passions

    ERIC Educational Resources Information Center

    Davis, Noah

    2007-01-01

    This article describes how the Watson fellowships give recipients an opportunity to test-drive their passions and see if they could lead to a career path. Over the last 40 years, the Thomas J. Watson Foundation has awarded $29 million in fellowships to seniors graduating from 50 mostly top-tier colleges with fewer than 3,000 students. In 2007, 50…

  7. Anomalous-viscosity current drive

    DOEpatents

    Stix, T.H.; Ono, M.

    1986-04-25

    The present invention relates to a method and apparatus for maintaining a steady-state current for magnetically confining the plasma in a toroidal magnetic confinement device using anomalous viscosity current drive. A second aspect of this invention relates to an apparatus and method for the start-up of a magnetically confined toroidal plasma.

  8. Drive axle for electric vehicle

    SciTech Connect

    Travis, J.M.

    1981-06-02

    An electric powered vehicle drive axle is disclosed. The axle of the present invention comprises a ring gear; a first pinion gear for rotating the ring gear; a differential carried by the ring gear; a pair of axle shafts driven by the differential for rotatably driving a pair of drive wheels; the device supported and enclosed by a housing. A second pinion gear is employed which rotatably engages the ring gear. A first electric motor rotatably connected to the first pinion gear is connected to a power source for rotatably driving the vehicle. A second electric motor/generator is connected to the second pinion gear and electrically connected to the power source. The second electric motor/generator selectively powers the differential or derives power from the differential to recharge the power source as dictated by the power needs of the electric vehicle. A plurality of bevel gears are deployed along the length of the axles. Each bevel gear is rotatably connected to a pair of opposed bevel gears, each opposed bevel gear is rotatably connected to an electric motor/generator. By selectively and electrically causing the plurality of motors/generators to either power the axle or be powered by the axle optimum efficiency and recharging of the battery over a range of vehicle operating conditions is obtained.

  9. Cannabis Effects on Driving Skills

    PubMed Central

    Hartman, Rebecca L.; Huestis, Marilyn A.

    2013-01-01

    BACKGROUND Cannabis is the most prevalent illicit drug identified in impaired drivers. The effects of cannabis on driving continue to be debated, making prosecution and legislation difficult. Historically, delays in sample collection, evaluating the inactive Δ9-tetrahydrocannabinol (THC) metabolite 11-nor-9-carboxy-THC, and polydrug use have complicated epidemiologic evaluations of driver impairment after cannabis use. CONTENT We review and evaluate the current literature on cannabis’ effects on driving, highlighting the epidemiologic and experimental data. Epidemiologic data show that the risk of involvement in a motor vehicle accident (MVA) increases approximately 2-fold after cannabis smoking. The adjusted risk of driver culpability also increases substantially, particularly with increased blood THC concentrations. Studies that have used urine as the biological matrix have not shown an association between cannabis and crash risk. Experimental data show that drivers attempt to compensate by driving more slowly after smoking cannabis, but control deteriorates with increasing task complexity. Cannabis smoking increases lane weaving and impaired cognitive function. Critical-tracking tests, reaction times, divided-attention tasks, and lane-position variability all show cannabis-induced impairment. Despite purported tolerance in frequent smokers, complex tasks still show impairment. Combining cannabis with alcohol enhances impairment, especially lane weaving. SUMMARY Differences in study designs frequently account for inconsistencies in results between studies. Participant-selection bias and confounding factors attenuate ostensible cannabis effects, but the association with MVA often retains significance. Evidence suggests recent smoking and/or blood THC concentrations 2–5 ng/mL are associated with substantial driving impairment, particularly in occasional smokers. Future cannabis-and-driving research should emphasize challenging tasks, such as divided attention

  10. Neural substrates of driving behaviour

    PubMed Central

    Spiers, Hugo J.; Maguire, Eleanor A.

    2007-01-01

    Driving a vehicle is an indispensable daily behaviour for many people, yet we know little about how it is supported by the brain. Given that driving in the real world involves the engagement of many cognitive systems that rapidly change to meet varying environmental demands, identifying its neural basis presents substantial problems. By employing a unique combination of functional magnetic resonance imaging (fMRI), an accurate interactive virtual simulation of a bustling central London (UK) and a retrospective verbal report protocol, we surmounted these difficulties. We identified different events that characterise the driving process on a second by second basis and the brain regions that underlie them. Prepared actions such as starting, turning, reversing and stopping were associated with a common network comprised of premotor, parietal and cerebellar regions. Each prepared action also recruited additional brain areas. We also observed unexpected hazardous events such as swerving and avoiding collisions that were associated with activation of lateral occipital and parietal regions, insula, as well as a more posterior region in the medial premotor cortex than prepared actions. By contrast, planning future actions and monitoring fellow road users were associated with activity in superior parietal, lateral occipital cortices and the cerebellum. The anterior pre-SMA was also recruited during action planning. The right lateral prefrontal cortex was specifically engaged during the processing of road traffic rules. By systematically characterising the brain dynamics underlying naturalistic driving behaviour in a real city, our findings may have implications for how driving competence is considered in the context of neurological damage. PMID:17412611

  11. Configuring the National Ignition Facility for direct-drive experiments

    SciTech Connect

    Eimerl, D.

    1995-07-01

    The National Ignition Facility (NIF) is a project whose primary mission is to provide an above-ground experimental capability for maintaining nuclear competence and weapons effects simulation, and to pursue the achievement of fusion ignition utilizing solid state lasers as the energy driver. In this facility a large number of laser beams are focused onto a small target located at the center of a spherical target chamber. The laser energy is delivered in a few billionths of a second, raising the temperature and density of the nuclear materials in the target to levels where significant thermonuclear energy is released. The thermonuclear reaction proceeds very rapidly, so that the target materials remain confined by their own inertia during the thermonuclear reaction. This type of approach is called inertial confinement fusion (ICF). The proposed project is described in a conceptual design report (CDR) that was released in May 1994. Early in FY95, a collaboration between the University of Rochester and the Lawrence Livermore National Laboratory was established to study reconfiguring the NIF to accommodate direct-drive experiments. The present paper is a report to the scientific community, primarily the scientists and engineers working on the design of the NIF. It represents results from work in progress, specifically work completed by the end of the second quarter FY95. This report has two main sections. The first describes the target requirements on the laser drive, and the second part describes how the NIF laser can be configured to accommodate both indirect and direct drive. The report includes a description of the scientific basis for these conclusions. Though a complete picture does not exist, the present understanding is sufficient to conclude that the primary target requirements and laser functional requirements for indirect and direct drive are quite compatible. It is evidently straightforward to reconfigure the NIF to accommodate direct and indirect drive.

  12. Meiotic drive and evolution of female choice.

    PubMed

    Reinhold, K; Engqvist, L; Misof, B; Kurtz, J

    1999-07-01

    As a special version of the good-genes hypothesis, it was recently proposed that females could benefit from choosing drive-resistant males in a meiotic drive system. Here, we examine with a three-locus, six-allele population genetic model whether female choice for drive resistance can evolve. An allele leading to female preference for drive-resistant males was introduced at low frequency into a population polymorphic for meiotic drive and drive resistance. Our simulations show that female choice of drive-resistant males is disadvantageous when resistance is Y-linked. This disadvantage occurs because, at equilibrium, drive-resistant males have lower reproductive success than drive-susceptible males. Thus, female choice of drive-susceptible males can evolve when resistance is Y-linked. When resistance is autosomal, selection on female choice for drive resistance is less strong and depends on the frequency of choice: female preference of resistant males is favoured when choice is rare and disadvantageous when choice is frequent, leading to a stable equilibrium at a low frequency of the choice allele. Independent of the location of drive resistance alleles, males with the non-driving allele always have above average reproductive success. Female choice is therefore beneficial when choosy females prefer males with the non-driving allele.

  13. Meiotic drive and evolution of female choice.

    PubMed Central

    Reinhold, K; Engqvist, L; Misof, B; Kurtz, J

    1999-01-01

    As a special version of the good-genes hypothesis, it was recently proposed that females could benefit from choosing drive-resistant males in a meiotic drive system. Here, we examine with a three-locus, six-allele population genetic model whether female choice for drive resistance can evolve. An allele leading to female preference for drive-resistant males was introduced at low frequency into a population polymorphic for meiotic drive and drive resistance. Our simulations show that female choice of drive-resistant males is disadvantageous when resistance is Y-linked. This disadvantage occurs because, at equilibrium, drive-resistant males have lower reproductive success than drive-susceptible males. Thus, female choice of drive-susceptible males can evolve when resistance is Y-linked. When resistance is autosomal, selection on female choice for drive resistance is less strong and depends on the frequency of choice: female preference of resistant males is favoured when choice is rare and disadvantageous when choice is frequent, leading to a stable equilibrium at a low frequency of the choice allele. Independent of the location of drive resistance alleles, males with the non-driving allele always have above average reproductive success. Female choice is therefore beneficial when choosy females prefer males with the non-driving allele. PMID:10445289

  14. Stability and skill in driving.

    PubMed

    Treffner, Paul; Barrett, Rod; Petersen, Andrew

    2002-12-01

    Two experiments addressed the relation between postural stability, perceptual sensitivity, and stability of driving performance. A vehicle was fitted with differential GPS for measuring position and speed, position sensors for measuring brake and accelerator depression, force transducers for measuring door, console and footrest bracing forces, and an accelerometer for measuring the 3D accelerations of the vehicle. In Experiment 1, we investigated whether the initiation of deceleration and the control of braking might be due to sensitivity to the perceptual variable tau, which specifies time-to-contact (TTC), and in particular, whether its first derivative, tau-dot, is used to maintain a constant deceleration profile. Using both untrained experienced drivers (EDs) and trained driving instructors from the Holden Performance Driving Centre (HPDC), results confirmed that, regardless of skill level, tau-dot was maintained at a value close to 0.5 and, as predicted by Lee [Perception 5 (1976) 437], braking was initiated when TTC approximately 5 s. In Experiment 2, we wished to quantify the purported differences in driving behaviour between EDs and HPDC instructors during a variety of everyday manoeuvres. Results indicated that instructors utilised a different cornering trajectory, a different emergency braking strategy, and were able to perform a high-speed swerve and recovery task more effectively than the EDs. In general, the instructors applied greater bracing forces using the door and console compared with EDs. The instructors also applied greater footrest forces during emergency braking than did the EDs. The greater use of bracing by instructor drivers to resist g-forces represents a strategy of active stabilisation that enhances both postural stability, as well as overall stability and consistency of driving performance. Results are discussed with regard to the dynamics of perceptual-motor coordination, and how increased stability might improve sensitivity to

  15. Magnetically Coupled Adjustable Speed Drive Systems

    SciTech Connect

    Chvala, William D.; Winiarski, David W.

    2002-08-18

    Adjustable speed drive (ASD) technologies have the ability to precisely control motor sytems output and produce a numbr of benefits including energy and demand savings. This report examines the performance and cost effectiveness of a specific class of ASDs called magnetically-coupled adjustable speed drives (MC-ASD) which use the strength of a magnetic field to control the amount of torque transferred between motor and drive shaft. The MagnaDrive Adjustable Speed Coupling System uses fixed rare-earth magnets and varies the distance between rotating plates in the assembly. the PAYBACK Variable Speed Drive uses an electromagnet to control the speed of the drive

  16. Warp Drive - A New Approach

    NASA Astrophysics Data System (ADS)

    Obousy, R. K.; Cleaver, G.

    Certain classes of higher dimensional models suggest that the Casimir Effect is a candidate for the cosmological constant. In this paper we demonstrate that a sufficiently advanced civilization could, in principal, manipulate the radius of the extra dimension to locally adjust the value of the cosmological constant. This adjustment could be tuned to generate an expansion/ contraction of spacetime around a spacecraft creating an exotic form of field-propulsion. Due to the fact that spacetime expansion itself is not restricted by relativity, a faster-than-light `warp drive' could be created. Calculations of the energy requirements of such a drive are performed and an `ultimate' speed limit, based on the Planckian limits on the size of the extra dimensions is found.

  17. Microsaccades generated during car driving.

    PubMed

    Miki, Shuntaro; Hirata, Yutaka

    2013-01-01

    Microsaccades together with drift and tremor are fixational eye movements that are generated when we try to fixate our gaze on a visual target. Besides their function in vision to prevent neural adaptation to unchanging retinal image, microsaccades have been studied in neuroscience as an indicator of attentional states for the last decade. Most of microsaccade researches have been conducted in unnatural laboratory environments, using controlled artificial visual stimuli. Thus, little is known about the characteristics of microsaccades in natural viewing conditions. Here we attempted to evaluate microsaccades during car driving condition in the aim of estimating driver's spatial attention. We demonstrate that microsaccades are generated during car driving, and the rate of microsaccade generation is modulated by road conditions such as appearance of pedestrians or/and other cars.

  18. Relationship Between Obesity and Driving.

    PubMed

    Kay, Gary G; McLaughlin, David

    2014-09-01

    Obesity, which has become epidemic throughout many parts of the world, is known to be a risk factor for a range of diseases including hypertension, diabetes, and vascular disease. Based on this review, it also appears that obesity is associated with increased crash risk and increased risk of serious or fatal injury in a crash. The problem is particularly an issue for commercial truck drivers. Data are presented showing the high prevalence of obesity in truck drivers. Inadequate sleep, poor nutrition, lack of exercise, and the sedentary nature of driving all contribute to the risk of obesity. The obesity related condition of obstructive sleep apnea (OSA) is known to increase crash risk. Treatment of this condition has been demonstrated to improve driving performance and to reduce crash risk. Screening truck drivers for obesity related health conditions, such as OSA, would be expected to result in public safety benefits. PMID:26626764

  19. Granular gases under extreme driving

    NASA Astrophysics Data System (ADS)

    Kang, W.; Machta, J.; Ben-Naim, E.

    2010-08-01

    We study inelastic gases in two dimensions using event-driven molecular-dynamics simulations. Our focus is the nature of the stationary state attained by rare injection of large amounts of energy to balance the dissipation due to collisions. We find that under such extreme driving, with the injection rate much smaller than the collision rate, the velocity distribution has a power-law high-energy tail. The numerically measured exponent characterizing this tail is in excellent agreement with predictions of kinetic theory over a wide range of system parameters. We conclude that driving by rare but powerful energy injection leads to a well-mixed gas and constitutes an alternative mechanism for agitating granular matter. In this distinct nonequilibrium steady state, energy cascades from large to small scales. Our simulations also show that when the injection rate is comparable with the collision rate, the velocity distribution has a stretched exponential tail.

  20. Electric vehicle drive train components

    SciTech Connect

    Silver, F.

    1994-12-31

    Power Control Systems has developed a family of electric vehicle drive systems that range from 65 horsepower through 300 horse power. These propulsion systems support vehicle applications ranging from light cars and pickups to buses and trucks weighing as much as 40,000 lbs (18,400 kg). These robust systems are designed specifically for automotive applications including safety, electromagnetic emissions, and environment ruggedness. Dolphin Drive Systems are very flexible. Their inverter controllers are programmable and can be provided as stand alone components matched to customer specified motors. A selection of pre-calibrated systems including motor and inverter/controller can be provided. Accessory tools are also available for customer self programming. Dolphin Drive Systems provide precision control of AC induction motors providing excellent torque-speed performance usually eliminating the need for multistage transmissions. In addition, they are very efficient over a wide speed/torque range. This provides for excellent power management over a variety of continuous speed and stop and go applications.

  1. Warp drive space-time

    NASA Astrophysics Data System (ADS)

    González-Díaz, Pedro F.

    2000-08-01

    In this paper the problem of the quantum stability of the two-dimensional warp drive spacetime moving with an apparent faster than light velocity is considered. We regard as a maximum extension beyond the event horizon of that spacetime its embedding in a three-dimensional Minkowskian space with the topology of the corresponding Misner space. It is obtained that the interior of the spaceship bubble becomes then a multiply connected nonchronal region with closed spacelike curves and that the most natural vacuum allows quantum fluctuations which do not induce any divergent behavior of the renormalized stress-energy tensor, even on the event (Cauchy) chronology horizon. In such a case, the horizon encloses closed timelike curves only at scales close to the Planck length, so that the warp drive satisfies Ford's negative energy-time inequality. Also found is a connection between the superluminal two-dimensional warp drive space and two-dimensional gravitational kinks. This connection allows us to generalize the considered Alcubierre metric to a standard, nonstatic metric which is only describable on two different coordinate patches.

  2. Effect of cognitive status on self-regulatory driving behavior in older adults: an assessment of naturalistic driving using in-car video recordings.

    PubMed

    Festa, Elena K; Ott, Brian R; Manning, Kevin J; Davis, Jennifer D; Heindel, William C

    2013-03-01

    Previous findings that older drivers engage in strategic self-regulatory behaviors to minimize perceived safety risks are primarily based on survey reports rather than actual behavior. This study analyzed in-car video recording of naturalistic driving of 18 patients with Alzheimer disease (AD) and 20 age-matched controls in order to (1) characterize self-regulatory behaviors engaged by older drivers and (2) assess how behaviors change with cognitive impairment. Only participants who were rated "safe" on a prior standardized road test were selected for this study. Both groups drove primarily in environments that minimized the demands on driving skill and that incurred the least risk for involvement in major crashes. Patients with AD displayed further restrictions of driving behavior beyond those of healthy elderly individuals, suggesting additional regulation on the basis of cognitive status. These data provide critical empirical support for findings from previous survey studies indicating an overall reduction in driving mobility among older drivers with cognitive impairment. PMID:23385363

  3. Behavioral Impact of Graduated Driver Licensing on Teenage Driving Risk and Exposure1

    PubMed Central

    Karaca-Mandic, Pinar; Ridgeway, Greg

    2009-01-01

    Graduated Driver Licensing (GDL) is a critical policy tool for potentially improving teenage driving while reducing teen accident exposure. While previous studies demonstrated that GDL reduces teenage involvement in fatal crashes, much remains unanswered. We explore the mechanisms through which GDL influences accident rates as well as its long term effectiveness on teen driving. In particular, we investigate; 1) whether GDL policies improve teenage driving behavior, or simply reduce teenage prevalence on the roads; 2) whether GDL exposed teens become better drivers in later years. We employ a unique data source, the State Data System, which contains all police reported accidents (fatal and non-fatal) during 1990–2005 for twelve states. We estimate a structural model that separately identifies GDL s effect on relative teenage prevalence and relative teenage riskiness. Identification of the model is driven by the relative numbers of crashes between two teenagers, two adults, or a teenager and an adult. We find that the GDL policies reduce the number of 15–17 year-old accidents by limiting the amount of teenage driving rather than by improving teenage driving. This prevalence reduction primarily occurs at night and stricter GDL policies, especially those with nighttime driving restrictions, are the most effective. Finally, we find that teen driving quality does not improve ex-post GDL exposure. PMID:19942310

  4. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  5. 77 FR 51610 - Distracted Driving Grant Program

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-24

    ... National Highway Traffic Safety Administration Distracted Driving Grant Program AGENCY: Department of... and enforcing distracted driving laws. The FY 2013 funds are subject to an annual obligation... FY 2013 may be less than the amount identified above. A State's distracted driving law must...

  6. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  7. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  8. 25 CFR 11.445 - Driving violations.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 25 Indians 1 2013-04-01 2013-04-01 false Driving violations. 11.445 Section 11.445 Indians BUREAU... ORDER CODE Criminal Offenses § 11.445 Driving violations. (a) A person who shall operate any vehicle in a manner dangerous to the public safety is guilty of reckless driving, a petty misdemeanor,...

  9. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  10. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  11. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  12. 25 CFR 11.445 - Driving violations.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 25 Indians 1 2014-04-01 2014-04-01 false Driving violations. 11.445 Section 11.445 Indians BUREAU... ORDER CODE Criminal Offenses § 11.445 Driving violations. (a) A person who shall operate any vehicle in a manner dangerous to the public safety is guilty of reckless driving, a petty misdemeanor,...

  13. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  14. 25 CFR 11.445 - Driving violations.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 25 Indians 1 2012-04-01 2011-04-01 true Driving violations. 11.445 Section 11.445 Indians BUREAU... ORDER CODE Criminal Offenses § 11.445 Driving violations. (a) A person who shall operate any vehicle in a manner dangerous to the public safety is guilty of reckless driving, a petty misdemeanor,...

  15. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  16. 30 CFR 75.1727 - Drive belts.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Drive belts. 75.1727 Section 75.1727 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Miscellaneous § 75.1727 Drive belts. (a) Drive belts shall not...

  17. 25 CFR 11.445 - Driving violations.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 25 Indians 1 2010-04-01 2010-04-01 false Driving violations. 11.445 Section 11.445 Indians BUREAU... ORDER CODE Criminal Offenses § 11.445 Driving violations. (a) A person who shall operate any vehicle in a manner dangerous to the public safety is guilty of reckless driving, a petty misdemeanor,...

  18. 30 CFR 77.406 - Drive belts.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Drive belts. 77.406 Section 77.406 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR COAL MINE SAFETY AND HEALTH MANDATORY... Mechanical Equipment § 77.406 Drive belts. (a) Drive belts shall not be shifted while in motion unless...

  19. 25 CFR 11.445 - Driving violations.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 25 Indians 1 2011-04-01 2011-04-01 false Driving violations. 11.445 Section 11.445 Indians BUREAU... ORDER CODE Criminal Offenses § 11.445 Driving violations. (a) A person who shall operate any vehicle in a manner dangerous to the public safety is guilty of reckless driving, a petty misdemeanor,...

  20. Mindfulness predicts less texting while driving among young adults: Examining attention- and emotion-regulation motives as potential mediators

    PubMed Central

    Feldman, Greg; Greeson, Jeff; Renna, Megan; Robbins-Monteith, Kendra

    2011-01-01

    Many young adult drivers read and send text messages while driving despite clear safety risks. Understanding predictors of texting-while-driving may help to indentify relevant targets for interventions to reduce this dangerous behavior. The present study examined whether individual differences in mindfulness is associated with texting-while-driving in a sample of young-adult drivers. Using path analysis, we tested whether this relationship would be mediated by the degree to which individuals use text-messaging as a means of reducing unpleasant emotions (emotion-regulation motives) and the degree to which individuals limit texting in order to focus on present-moment experiences (attention-regulation motives). Individuals lower in mindfulness reported more frequent texting-while-driving and this relationship appeared to be mediated primarily by emotion-regulation motives. Results may help inform the development of mindfulness-based interventions to prevent texting-while-driving. PMID:22031789

  1. Evidence for meiotic drive at the myotonic dystrophy locus

    SciTech Connect

    Shaw, A.M.; Barnetson, R.A.; Phillips, M.F.

    1994-09-01

    Myotonic dystrophy (DM), an autosomal dominant disorder, is the most common form of adult muscular dystrophy, affecting at least 1 in 8000 of the population. It is a multisystemic disorder, primarily characterized by myotonia, muscle wasting and cataract. The molecular basis of DM is an expanded CTG repeat located within the 3{prime} untranslated region of a putative serine-threonine protein kinase on chromosome 19q13.3. DM exhibits anticipation, that is, with successive generations there is increasing disease severity and earlier age of onset. This mechanism and the fact that the origin of the disease has been attributed to one or a small number of founder chromosomes suggests that, in time, DM should die out. Meiotic drive has been described as a way in which certain alleles are transmitted to succeeding generations in preference to others: preferential transmission of large CTG alleles may account for their continued existence in the gene pool. There is evidence that a CTG allele with > 19 repeats may gradually increase in repeat number over many generations until it is sufficiently large to give a DM phenotype. We report a study of 495 transmissions from individuals heterozygous for the CTG repeat and with repeat numbers within the normal range (5-30). Alleles were simply classified as large or small relative to the other allele in an individual. Of 242 male meioses, 126 transmissions from parent to child were of the larger allele to their offspring (57.7%, p=0.014). This shows that there is strong evidence for meiotic drive favoring the transmission of the larger DM allele in unaffected individuals. Contrary to a previous report of meiotic drive in the male, we have shown that females preferentially transmit the larger DM allele. Taken together, the data suggest the occurrence of meiotic drive in both males and females in this locus.

  2. Can Active Navigation Be as Good as Driving? A Comparison of Spatial Memory in Drivers and Backseat Drivers

    ERIC Educational Resources Information Center

    von Stulpnagel, Rul; Steffens, Melanie C.

    2012-01-01

    When driving a vehicle, either the driver or a passenger (henceforth: backseat driver) may be responsible for navigation. Research on active navigation, primarily addressed in virtual environments, suggests that controlling navigation is more central for spatial learning than controlling movement. To test this assumption in a real-world scenario,…

  3. Fluid cooled vehicle drive module

    DOEpatents

    Beihoff, Bruce C.; Radosevich, Lawrence D.; Meyer, Andreas A.; Gollhardt, Neil; Kannenberg, Daniel G.

    2005-11-15

    An electric vehicle drive includes a support may receive one or more power electronic circuits. The support may aid in removing heat from the circuits through fluid circulating through the support. The support, in conjunction with other packaging features may form a shield from both external EM/RFI and from interference generated by operation of the power electronic circuits. Features may be provided to permit and enhance connection of the circuitry to external circuitry, such as improved terminal configurations. Modular units may be assembled that may be coupled to electronic circuitry via plug-in arrangements or through interface with a backplane or similar mounting and interconnecting structures.

  4. Driving trajectories in chaotic scattering.

    PubMed

    Macau, Elbert E N; Caldas, Iberê L

    2002-02-01

    In this work we introduce a general approach for targeting in chaotic scattering that can be used to find a transfer trajectory between any two points located inside the scattering region. We show that this method can be used in association with a control of chaos strategy to drive around and keep a particle inside the scattering region. As an illustration of how powerful this approach is, we use it in a case of practical interest in celestial mechanics in which it is desired to control the evolution of two satellites that evolve around a large central body. PMID:11863640

  5. Driving trajectories in chaotic scattering.

    PubMed

    Macau, Elbert E N; Caldas, Iberê L

    2002-02-01

    In this work we introduce a general approach for targeting in chaotic scattering that can be used to find a transfer trajectory between any two points located inside the scattering region. We show that this method can be used in association with a control of chaos strategy to drive around and keep a particle inside the scattering region. As an illustration of how powerful this approach is, we use it in a case of practical interest in celestial mechanics in which it is desired to control the evolution of two satellites that evolve around a large central body.

  6. Efficient alternatives for electric drives

    SciTech Connect

    Comnes, G.A.; Barnes, R.W.

    1987-11-01

    This analysis of industrial electric motors describes the current motor stock, its energy use and operating characteristics, and innovations that could change current use patterns. It provides calculations characterizing the economic attractiveness of several existing and potential options. One attractive option given particular attention is the adjustable-speed drive which can replace throttles or valves for many pumping operations. A major conclusion is that, throughout industry, options that are both energy-saving and economically attractive appear to penetrate markets more slowly than would be socially optimal. The final section examines characteristics of industry that may contribute to slow market penetration. 29 refs., 14 figs., 14 tabs.

  7. Computer-Aided Remote Driving

    NASA Technical Reports Server (NTRS)

    Wilcox, Brian H.

    1994-01-01

    System for remote control of robotic land vehicle requires only small radio-communication bandwidth. Twin video cameras on vehicle create stereoscopic images. Operator views cross-polarized images on two cathode-ray tubes through correspondingly polarized spectacles. By use of cursor on frozen image, remote operator designates path. Vehicle proceeds to follow path, by use of limited degree of autonomous control to cope with unexpected conditions. System concept, called "computer-aided remote driving" (CARD), potentially useful in exploration of other planets, military surveillance, firefighting, and clean-up of hazardous materials.

  8. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  9. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 4 2011-07-01 2011-07-01 false Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  10. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 4 2012-07-01 2011-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  11. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 4 2013-07-01 2013-07-01 false Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  12. 32 CFR 634.14 - Restoration of driving privileges upon acquittal of intoxicated driving.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Restoration of driving privileges upon acquittal of intoxicated driving. 634.14 Section 634.14 National Defense Department of Defense (Continued... SUPERVISION Driving Privileges § 634.14 Restoration of driving privileges upon acquittal of...

  13. Dual excitation multiphase electrostatic drive

    SciTech Connect

    Niino, Toshiki; Higuchi, Toshiro |; Egawa, Saku

    1995-12-31

    A novel electrostatic drive technology named Dual Excitation Multiphase Electrostatic Drive (DEMED) was presented. A basic DEMED consisted of two plastic films in which 3-phase parallel electrodes were embedded and was driven by a 3-phase ac excitation to the electrodes. Static characteristics of DEMED were calculated and tested and the results agreed very well. Three prototype motors of DEMED were fabricated using commercially available technique. The first prototype consisted of a single slider and stator and generated a linear motion with a slider`s motion range of about 5mm. It weighed 7g and generated a power of 1.6W and a thrust force of 4.4N. The second prototype consisted of 50 layer stack of linear motors, summing their outputs. It weighed 3.6kg and generated a propulsive force of 310N being powered with boosted commercial 3-phase electricity. The third prototype consisted of a rotor and a stator in which electrodes were arranged radially and generated rotational motion. The maximum power of 36mW was generated by the prototype weighing only 260mg for its rotor and stator. From the results of the numerical calculation, a practical design methodology for the motor was determined. An optimal design for a motor employing currently available material and fabrication techniques is provided as an example. Analyses predict that force generation over the interfacial area between the slider and stator of this motor would be 3,900N/m{sup 2}.

  14. Four-wheel drive car

    SciTech Connect

    Ashikawa, N.

    1986-03-25

    A drive train in a four-wheel drive vehicle is described having an engine mounted on one end with a crankshaft oriented transverse to the direction of vehicle travel which consists of: a transmission having an output gear driven by the crankshaft and rotatable around an axis parallel to the axis of the crankshaft; a reduction gear operatively engaged with the output gear; a first differential gear having a gear and being concentrically engaged with the reduction gear to transmit the output of the reduction gear in a divided manner; a second differential gear transmitting power from one output of the differential gear to left and right wheels of the one end of the vehicle; a transmission gear meshing with the gear of the first differential gear for transmitting power from another output of the first differential gear in a direction generally perpendicular to the crankshaft through a propeller shaft to the other end of the vehicle, opposite the one end; a third differential gear receiving power from the propeller shaft for transmitting power to left and right wheels on the other end; and wherein a mesh portion where the transmission gear meshes with the gear of the first differential gear is closer to the crankshaft axis of engine than is the axis of the reduction gear.

  15. Driving Extreme Efficiency to Market

    NASA Astrophysics Data System (ADS)

    Garbesi, Karina

    2014-03-01

    The rapid development of extremely energy efficient appliances and equipment is essential to curtail catastrophic climate disruption. This will require the on-going development of products that apply all best-practices and that take advantage of the synergies of hybridization and building integration. Beyond that, it requires the development of new disruptive technologies and concepts. To facilitate these goals, in 2011 the Lawrence Berkeley National Laboratory and the U.S. Department of Energy launched the Max Tech and Beyond Design Competition for Ultra-Low-Energy-Use Appliances and Equipment. Now in its third year, the competition supports faculty-lead student design teams at U.S. universities to develop and test new technology prototypes. This talk describes what the competition and the Max Tech Program are doing to drive such rapid technology progress and to facilitate the entry to the market of successful Max Tech prototypes. The talk also initiates a discussion of physicists' unique role in driving that technology progress faster and farther. Emerging Technologies, Building Technologies Office, U.S. Department of Energy.

  16. Exposure to Movie Reckless Driving in Early Adolescence Predicts Reckless, but Not Inattentive Driving

    PubMed Central

    Kostermans, Evelien; Stoolmiller, Mike; de Leeuw, Rebecca N. H.; Engels, Rutger C. M. E.; Sargent, James D.

    2014-01-01

    Objective We examine the association between exposure to depictions of reckless driving in movies and unsafe driving, modeling inattentive and reckless driving as separate outcomes. Methods Data were obtained by telephone from 1,630 US adolescents aged 10 to 14 years at baseline who were drivers at a survey 6 years later. Exposure to movie reckless driving was measured based on movies seen from a randomly selected list of 50 movie titles that had been content coded for reckless driving among characters. Associations were tested with inattentive and reckless driving behaviors in the subsequent survey–controlling for baseline age, sex, socioeconomic status, parental education, school performance, extracurricular activities, daily television and video/computer game exposure, number of movies watched per week, self-regulation and sensation seeking. Results Exposure to movie reckless driving was common, with approximately 10% of movie characters having driven recklessly. Confirmatory factor analysis revealed a significant distinction between items tapping reckless and inattentive driving at the 6th wave. Age and exposure to movie reckless driving at baseline were directly associated with wave-6 reckless (but not inattentive) driving. Additionally, growth in sensation seeking mediated a prospective relation between the total number of movies watched per week at baseline and reckless driving, independent of exposure to movie reckless driving. Males and high sensation seekers reported lower seatbelt usage and more reckless driving, whereas lower self-regulation predicted inattentive driving. Discussion In this study, exposure to movie reckless driving during early adolescence predicted adolescents’ reckless driving, suggesting a direct modeling effect. Other aspects of movies were also associated with reckless driving, with that association mediated through growth in sensation seeking. Predictors of reckless driving were different from predictors of inattentive driving

  17. Nanoparticles affect PCR primarily via surface interactions with PCR components: using amino-modified silica-coated magnetic nanoparticles as a main model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Nanomaterials have been widely reported to affect the polymerase chain reaction (PCR). However, many studies in which these effects were observed were not comprehensive, and many of the proposed mechanisms have been primarily speculative. In this work, we used amino-modified silica-coated magnetic n...

  18. Circuit for Driving Piezoelectric Transducers

    NASA Technical Reports Server (NTRS)

    Randall, David P.; Chapsky, Jacob

    2009-01-01

    The figure schematically depicts an oscillator circuit for driving a piezoelectric transducer to excite vibrations in a mechanical structure. The circuit was designed and built to satisfy application-specific requirements to drive a selected one of 16 such transducers at a regulated amplitude and frequency chosen to optimize the amount of work performed by the transducer and to compensate for both (1) temporal variations of the resonance frequency and damping time of each transducer and (2) initially unknown differences among the resonance frequencies and damping times of different transducers. In other words, the circuit is designed to adjust itself to optimize the performance of whichever transducer is selected at any given time. The basic design concept may be adaptable to other applications that involve the use of piezoelectric transducers in ultrasonic cleaners and other apparatuses in which high-frequency mechanical drives are utilized. This circuit includes three resistor-capacitor networks that, together with the selected piezoelectric transducer, constitute a band-pass filter having a peak response at a frequency of about 2 kHz, which is approximately the resonance frequency of the piezoelectric transducers. Gain for generating oscillations is provided by a power hybrid operational amplifier (U1). A junction field-effect transistor (Q1) in combination with a resistor (R4) is used as a voltage-variable resistor to control the magnitude of the oscillation. The voltage-variable resistor is part of a feedback control loop: Part of the output of the oscillator is rectified and filtered for use as a slow negative feedback to the gate of Q1 to keep the output amplitude constant. The response of this control loop is much slower than 2 kHz and, therefore, does not introduce significant distortion of the oscillator output, which is a fairly clean sine wave. The positive AC feedback needed to sustain oscillations is derived from sampling the current through the

  19. Alertness maintaining tasks (AMTs) while driving.

    PubMed

    Oron-Gilad, Tal; Ronen, Adi; Shinar, David

    2008-05-01

    We evaluated the effectiveness of alertness maintaining tasks (AMTs) on driver performance, subjective feelings, and psychophysiological state in monotonous simulated driving in two experiments. In the first experiment, 12 professional truck drivers participated in five sessions of simulated driving: driving only, driving with one of three AMTs (counterbalanced), and driving while listening to music. AMTs were not equally effective in maintaining alertness. The trivia AMT prevented driving performance deterioration, and increased alertness (measured by standardized HRV). The choice reaction time AMT was least demanding but also increased subjective sleepiness and reduced arousal (measured by alpha/beta ratio). The working memory AMT caused a significant decrement in driving speed, increased subjective fatigue, and was regarded by the participants as detrimental to driving. Trivia was preferred by the majority of the drivers over the other two AMTs. Experiment 2 further examined the utility of the trivia AMT. When the drivers engaged in the trivia AMT they maintained better driving performance and perceived the driving duration as shorter than the control condition. The two experiments demonstrated that AMTs can have a positive effect on alertness. The effect is localized in the sense that it does not persist beyond the period of the AMT activation.

  20. Drug addiction as drive satisfaction ("antidrive") dysfunction.

    PubMed

    Kostowski, Wojciech

    2002-01-01

    Drug addiction is a complex brain disorder, characterized by the loss of control over drug seeking and drug taking behavior, and by the risk of relapse, even after a prolonged period of abstinence. This disorder may have its source in a disturbed balance of drive-related behaviors, which control appetitive reactions aimed at seeking contact with an addictive substance. The act of consumption becomes more and more attractive, and the behavior takes on compulsive character. We suppose that drug addiction may involve a change in the mechanism of satisfaction of drives and states of satiation as well. To understand how the motivational processes are changed with the development of dependence, one must consider the mechanism of drive satisfaction and satiation states that occur in relation to the consumatory reflex. When a given drive is satisfied a state of fulfillment occurs. This state may be a result of a so-called "antidrive" mechanism (Konorski 1967). While a drive activity is characterized by general activation and tension, the drive satisfaction state ("antidrive") is characterized by relaxation and relief. When a particular drive is satisfied, the operation of other drives become possible. Therefore, we postulate that dysfunction of drive satisfaction leads to the sustained activation related to the current drug-related drive, which blocks the operation of other drives. In effect, uncontrolled compulsive appetitive behavior is released, and the operation of other drives is restrained, thus forcing the organism to focus on drug-related drive. The reason for an "antidrive" dysfunction may be related to adaptive changes which develop during a contact with an addictive substance.