SYNCHROTRON RADIATION, FREE ELECTRON LASER, APPLICATION OF NUCLEAR TECHNOLOGY, ETC.: A new cell for X-ray absorption spectroscopy study under high pressure

NASA Astrophysics Data System (ADS)

Zheng, Li-Rong; Che, Rong-Zheng; Liu, Jing; Du, Yong-Hua; Zhou, Ying-Li; Hu, Tian-Dou

2009-08-01

X-ray absorption fine structure (XAFS) spectroscopy is a powerful technique for the investigation of the local environment around selected atoms in condensed matter. XAFS under pressure is an important method for the synchrotron source. We design a cell for a high pressure XAFS experiment. Sintered boron carbide is used as the anvils of this high pressure cell in order to obtain a full XAFS spectrum free from diffraction peaks. In addition, a hydraulic pump was adopted to make in-suit pressure modulation. High quality XAFS spectra of ZrH2 under high pressure (up to 13 GPa) were obtained by this cell.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species.

PubMed

Dreher, Corinna E; Cummings, Molly E; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological factors.

An Analysis of Predator Selection to Affect Aposematic Coloration in a Poison Frog Species

PubMed Central

Dreher, Corinna E.; Cummings, Molly E.; Pröhl, Heike

2015-01-01

Natural selection is widely noted to drive divergence of phenotypic traits. Predation pressure can facilitate morphological divergence, for example the evolution of both cryptic and conspicuous coloration in animals. In this context Dendrobatid frogs have been used to study evolutionary forces inducing diversity in protective coloration. The polytypic strawberry poison frog (Oophaga pumilio) shows strong divergence in aposematic coloration among populations. To investigate whether predation pressure is important for color divergence among populations of O. pumilio we selected four mainland populations and two island populations from Costa Rica and Panama. Spectrometric measurements of body coloration were used to calculate color and brightness contrasts of frogs as an indicator of conspicuousness for the visual systems of several potential predators (avian, crab and snake) and a conspecific observer. Additionally, we conducted experiments using clay model frogs of different coloration to investigate whether the local coloration of frogs is better protected than non-local color morphs, and if predator communities vary among populations. Overall predation risk differed strongly among populations and interestingly was higher on the two island populations. Imprints on clay models indicated that birds are the main predators while attacks of other predators were rare. Furthermore, clay models of local coloration were equally likely to be attacked as those of non-local coloration. Overall conspicuousness (and brightness contrast) of local frogs was positively correlated with attack rates by birds across populations. Together with results from earlier studies we conclude that conspicuousness honestly indicates toxicity to avian predators. The different coloration patterns among populations of strawberry poison frogs in combination with behavior and toxicity might integrate into equally efficient anti-predator strategies depending on local predation and other ecological factors. PMID:26110826

Spatial Selection and Local Adaptation Jointly Shape Life-History Evolution during Range Expansion.

PubMed

Van Petegem, Katrien H P; Boeye, Jeroen; Stoks, Robby; Bonte, Dries

2016-11-01

In the context of climate change and species invasions, range shifts increasingly gain attention because the rates at which they occur in the Anthropocene induce rapid changes in biological assemblages. During range shifts, species experience multiple selection pressures. For poleward expansions in particular, it is difficult to interpret observed evolutionary dynamics because of the joint action of evolutionary processes related to spatial selection and to adaptation toward local climatic conditions. To disentangle the effects of these two processes, we integrated stochastic modeling and data from a common garden experiment, using the spider mite Tetranychus urticae as a model species. By linking the empirical data with those derived form a highly parameterized individual-based model, we infer that both spatial selection and local adaptation contributed to the observed latitudinal life-history divergence. Spatial selection best described variation in dispersal behavior, while variation in development was best explained by adaptation to the local climate. Divergence in life-history traits in species shifting poleward could consequently be jointly determined by contemporary evolutionary dynamics resulting from adaptation to the environmental gradient and from spatial selection. The integration of modeling with common garden experiments provides a powerful tool to study the contribution of these evolutionary processes on life-history evolution during range expansion.

Membrane permeable local anesthetics modulate NaV1.5 mechanosensitivity

PubMed Central

Beyder, Arthur; Strege, Peter R.; Bernard, Cheryl; Farrugia, Gianrico

2012-01-01

Voltage-gated sodium selective ion channel NaV1.5 is expressed in the heart and the gastrointestinal tract, which are mechanically active organs. NaV1.5 is mechanosensitive at stimuli that gate other mechanosensitive ion channels. Local anesthetic and antiarrhythmic drugs act upon NaV1.5 to modulate activity by multiple mechanisms. This study examined whether NaV1.5 mechanosensitivity is modulated by local anesthetics. NaV1.5 channels wereexpressed in HEK-293 cells, and mechanosensitivity was tested in cell-attached and excised inside-out configurations. Using a novel protocol with paired voltage ladders and short pressure pulses, negative patch pressure (-30 mmHg) in both configurations produced a hyperpolarizing shift in the half-point of the voltage-dependence of activation (V1/2a) and inactivation (V1/2i) by about -10 mV. Lidocaine (50 µM) inhibited the pressure-induced shift of V1/2a but not V1/2i. Lidocaine inhibited the tonic increase in pressure-induced peak current in a use-dependence protocol, but it did not otherwise affect use-dependent block. The local anesthetic benzocaine, which does not show use-dependent block, also effectively blocked a pressure-induced shift in V1/2a. Lidocaine inhibited mechanosensitivity in NaV1.5 at the local anesthetic binding site mutated (F1760A). However, a membrane impermeable lidocaine analog QX-314 did not affect mechanosensitivity of F1760A NaV1.5 when applied from either side of the membrane. These data suggest that the mechanism of lidocaine inhibition of the pressure-induced shift in the half-point of voltage-dependence of activation is separate from the mechanisms of use-dependent block. Modulation of NaV1.5 mechanosensitivity by the membrane permeable local anesthetics may require hydrophobic access and may involve membrane-protein interactions. PMID:22874086

Alternating evolutionary pressure in a genetic algorithm facilitates protein model selection

PubMed Central

Offman, Marc N; Tournier, Alexander L; Bates, Paul A

2008-01-01

Background Automatic protein modelling pipelines are becoming ever more accurate; this has come hand in hand with an increasingly complicated interplay between all components involved. Nevertheless, there are still potential improvements to be made in template selection, refinement and protein model selection. Results In the context of an automatic modelling pipeline, we analysed each step separately, revealing several non-intuitive trends and explored a new strategy for protein conformation sampling using Genetic Algorithms (GA). We apply the concept of alternating evolutionary pressure (AEP), i.e. intermediate rounds within the GA runs where unrestrained, linear growth of the model populations is allowed. Conclusion This approach improves the overall performance of the GA by allowing models to overcome local energy barriers. AEP enabled the selection of the best models in 40% of all targets; compared to 25% for a normal GA. PMID:18673557

Instrumentation for Examining Microbial Response to Changes In Environmental Pressures

NASA Technical Reports Server (NTRS)

Blaich, Justin; Storrs, Aaron; Wang, Jonathan; Ouandji, Cynthia; Arismendi, Dillon; Hernandez, Juliana; Sardesh, Nina; Ibanez, Cory; Owyang, Stephanie; Gentry, Diana

2016-01-01

The Automated Adaptive Directed Evolution Chamber (AADEC) is a device that allows operators to generate a micro-scale analog of real world systems that can be used to model the local-scale effects of climate change on microbial ecosystems. The AADEC uses an artificial environment to expose cultures of micro-organisms to environmental pressures, such as UV-C radiation, chemical toxins, and temperature. The AADEC autonomously exposes micro-organisms to selection pressures. This improves upon standard manual laboratory techniques: the process can take place over a longer period of time, involve more stressors, implement real-time adjustments based on the state of the population, and minimize the risk of contamination. We currently use UV-C radiation as the main selection pressure, UV-C is well studied both for its cell and DNA damaging effects as a type of selection pressure and for its related effectiveness as a mutagen; having these functions united makes it a good choice for a proof of concept. The AADEC roadmap includes expansion to different selection pressures, including heavy metal toxicity, temperature, and other forms of radiation.The AADEC uses closed-loop control to feedback the current state of the culture to the AADEC controller that modifies selection pressure intensity during experimentation, in this case culture density and growth rate. Culture density and growth rate are determined by measuring the optical density of the culture using 600 nm light. An array of 600 nm LEDs illuminate the culture and photodiodes are used to measure the shadow on the opposite side of the chamber.Previous experiments showed that we can produce a million fold increase to UV-C radiation over seven iterations. The most recent implements a microfluidic system that can expose cultures to multiple different selection pressures, perform non-survival based selection, and autonomously perform hundreds of exposure cycles. A scalable pump system gives the ability to pump in various different growth media to individual cultures and introduce chemical toxins during experimentation; AADEC can perform freeze and thaw cycles. We improved our baseline characterization by building a custom UV-C exposure hood, a shutter operates on a preset timer allowing the user to set exposure intensity consistently for multiple iterations.

Genome-wide evidence for divergent selection between populations of a major agricultural pathogen.

PubMed

Hartmann, Fanny E; McDonald, Bruce A; Croll, Daniel

2018-06-01

The genetic and environmental homogeneity in agricultural ecosystems is thought to impose strong and uniform selection pressures. However, the impact of this selection on plant pathogen genomes remains largely unknown. We aimed to identify the proportion of the genome and the specific gene functions under positive selection in populations of the fungal wheat pathogen Zymoseptoria tritici. First, we performed genome scans in four field populations that were sampled from different continents and on distinct wheat cultivars to test which genomic regions are under recent selection. Based on extended haplotype homozygosity and composite likelihood ratio tests, we identified 384 and 81 selective sweeps affecting 4% and 0.5% of the 35 Mb core genome, respectively. We found differences both in the number and the position of selective sweeps across the genome between populations. Using a XtX-based outlier detection approach, we identified 51 extremely divergent genomic regions between the allopatric populations, suggesting that divergent selection led to locally adapted pathogen populations. We performed an outlier detection analysis between two sympatric populations infecting two different wheat cultivars to identify evidence for host-driven selection. Selective sweep regions harboured genes that are likely to play a role in successfully establishing host infections. We also identified secondary metabolite gene clusters and an enrichment in genes encoding transporter and protein localization functions. The latter gene functions mediate responses to environmental stress, including interactions with the host. The distinct gene functions under selection indicate that both local host genotypes and abiotic factors contributed to local adaptation. © 2018 The Authors. Molecular Ecology Published by John Wiley & Sons Ltd.

The evolution of sexual size dimorphism in the house finch. II. Population divergence in relation to local selection.

PubMed

Badyaev, A V; Hill, G E; Stoehr, A M; Nolan, P M; McGraw, K J

2000-12-01

Recent colonization of ecologically distinct areas in North America by the house finch (Carpodacus mexicanus) was accompanied by strong population divergence in sexual size dimorphism. Here we examined whether this divergence was produced by population differences in local selection pressures acting on each sex. In a long-term study of recently established populations in Alabama, Michigan, and Montana, we examined three selection episodes for each sex: selection for pairing success, overwinter survival, and within-season fecundity. Populations varied in intensity of these selection episodes, the contribution of each episode to the net selection, and in the targets of selection. Direction and intensity of selection strongly differed between sexes, and different selection episodes often favored opposite changes in morphological traits. In each population, current net selection for sexual dimorphism was highly concordant with observed sexual dimorphism--in each population, selection for dimorphism was the strongest on the most dimorphic traits. Strong directional selection on sexually dimorphic traits, and similar intensities of selection in both sexes, suggest that in each of the recently established populations, both males and females are far from their local fitness optimum, and that sexual dimorphism has arisen from adaptive responses in both sexes. Population differences in patterns of selection on dimorphism, combined with both low levels of ontogenetic integration in heritable sexually dimorphic traits and sexual dimorphism in growth patterns, may account for the close correspondence between dimorphism in selection and observed dimorphism in morphology across house finch populations.

Amphibian Bioacoustics

NASA Astrophysics Data System (ADS)

Christensen-Dalsgaard, Jakob

Anuran amphibians (frogs and toads) of most of the 3,500 species that exist today are highly vocal animals. In most frogs, males will spend considerable energy on calling and incur sizeable predation risks and the females’ detection and localization of the calls of conspecific males is often a prerequisite for successful mating. Therefore, acoustic communication is evidently evolutionarily important in the anurans, and their auditory system is probably shaped by the selective pressures associated with production, detection and localization of the communication calls.

Supersonic turbulent boundary layers with periodic mechanical non-equilibrium

NASA Astrophysics Data System (ADS)

Ekoto, Isaac Wesley

Previous studies have shown that favorable pressure gradients reduce the turbulence levels and length scales in supersonic flow. Wall roughness has been shown to reduce the large-scales in wall bounded flow. Based on these previous observations new questions have been raised. The fundamental questions this dissertation addressed are: (1) What are the effects of wall topology with sharp versus blunt leading edges? and (2) Is it possible that a further reduction of turbulent scales can occur if surface roughness and favorable pressure gradients are combined? To answer these questions and to enhance the current experimental database, an experimental analysis was performed to provide high fidelity documentation of the mean and turbulent flow properties along with surface and flow visualizations of a high-speed (M = 2.86), high Reynolds number (Retheta ≈ 60,000) supersonic turbulent boundary layer distorted by curvature-induced favorable pressure gradients and large-scale ( k+s ≈ 300) uniform surface roughness. Nine models were tested at three separate locations. Three pressure gradient models strengths (a nominally zero, a weak, and a strong favorable pressure gradient) and three roughness topologies (aerodynamically smooth, square, and diamond shaped roughness elements) were used. Highly resolved planar measurements of mean and fluctuating velocity components were accomplished using particle image velocimetry. Stagnation pressure profiles were acquired with a traversing Pitot probe. Surface pressure distributions were characterized using pressure sensitive paint. Finally flow visualization was accomplished using schlieren photographs. Roughness topology had a significant effect on the boundary layer mean and turbulent properties due to shock boundary layer interactions. Favorable pressure gradients had the expected stabilizing effect on turbulent properties, but the improvements were less significant for models with surface roughness near the wall due to increased tendency towards flow separation. It was documented that proper roughness selection coupled with a sufficiently strong favorable pressure gradient produced regions of "negative" production in the transport of turbulent stress. This led to localized areas of significant turbulence stress reduction. With proper roughness selection and sufficient favorable pressure gradient strength, it is believed that localized relaminarization of the boundary layer is possible.

Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures.

PubMed

Chouteau, Mathieu; Llaurens, Violaine; Piron-Prunier, Florence; Joron, Mathieu

2017-08-01

Explaining the maintenance of adaptive diversity within populations is a long-standing goal in evolutionary biology, with important implications for conservation, medicine, and agriculture. Adaptation often leads to the fixation of beneficial alleles, and therefore it erodes local diversity so that understanding the coexistence of multiple adaptive phenotypes requires deciphering the ecological mechanisms that determine their respective benefits. Here, we show how antagonistic frequency-dependent selection (FDS), generated by natural and sexual selection acting on the same trait, maintains mimicry polymorphism in the toxic butterfly Heliconius numata Positive FDS imposed by predators on mimetic signals favors the fixation of the most abundant and best-protected wing-pattern morph, thereby limiting polymorphism. However, by using mate-choice experiments, we reveal disassortative mate preferences of the different wing-pattern morphs. The resulting negative FDS on wing-pattern alleles is consistent with the excess of heterozygote genotypes at the supergene locus controlling wing-pattern variation in natural populations of H. numata The combined effect of positive and negative FDS on visual signals is sufficient to maintain a diversity of morphs displaying accurate mimicry with other local prey, although some of the forms only provide moderate protection against predators. Our findings help understand how alternative adaptive phenotypes can be maintained within populations and emphasize the need to investigate interactions between selective pressures in other cases of puzzling adaptive polymorphism.

Polymorphism at a mimicry supergene maintained by opposing frequency-dependent selection pressures

PubMed Central

Chouteau, Mathieu; Llaurens, Violaine; Piron-Prunier, Florence; Joron, Mathieu

2017-01-01

Explaining the maintenance of adaptive diversity within populations is a long-standing goal in evolutionary biology, with important implications for conservation, medicine, and agriculture. Adaptation often leads to the fixation of beneficial alleles, and therefore it erodes local diversity so that understanding the coexistence of multiple adaptive phenotypes requires deciphering the ecological mechanisms that determine their respective benefits. Here, we show how antagonistic frequency-dependent selection (FDS), generated by natural and sexual selection acting on the same trait, maintains mimicry polymorphism in the toxic butterfly Heliconius numata. Positive FDS imposed by predators on mimetic signals favors the fixation of the most abundant and best-protected wing-pattern morph, thereby limiting polymorphism. However, by using mate-choice experiments, we reveal disassortative mate preferences of the different wing-pattern morphs. The resulting negative FDS on wing-pattern alleles is consistent with the excess of heterozygote genotypes at the supergene locus controlling wing-pattern variation in natural populations of H. numata. The combined effect of positive and negative FDS on visual signals is sufficient to maintain a diversity of morphs displaying accurate mimicry with other local prey, although some of the forms only provide moderate protection against predators. Our findings help understand how alternative adaptive phenotypes can be maintained within populations and emphasize the need to investigate interactions between selective pressures in other cases of puzzling adaptive polymorphism. PMID:28673971

Investigation of the reaction of liquid hydrogen with liquid air in a pressure tube

NASA Technical Reports Server (NTRS)

Karb, Erich H.

1987-01-01

A pressure tube should protect the FR-2 reactor from the consequences of a hydrogen-air reaction, which is conceivable in the breakdown of several safety devices of the planned cold neutron source Project FR-2/16. The magnitudes and time pattern of the pressures to be expected were investigated. In the geometry used and the ignition mechanism selected, which is comparable to the strongest ignition process conceivable in the reactor, the reaction proceeds with greater probability than combustion. The combustion is possibly smaller if local limited partial detonations are superimposed. The magnitude of the pressure was determined by the masses of the reaction partners, liquid H2 and liquid air, and determines their ratio to each other.

Blood pressure control with selective vagal nerve stimulation and minimal side effects

NASA Astrophysics Data System (ADS)

Plachta, Dennis T. T.; Gierthmuehlen, Mortimer; Cota, Oscar; Espinosa, Nayeli; Boeser, Fabian; Herrera, Taliana C.; Stieglitz, Thomas; Zentner, Joseph

2014-06-01

Objective. Hypertension is the largest threat to patient health and a burden to health care systems. Despite various options, 30% of patients do not respond sufficiently to medical treatment. Mechanoreceptors in the aortic arch relay blood pressure (BP) levels through vagal nerve (VN) fibers to the brainstem and trigger the baroreflex, lowering the BP. Selective electrical stimulation of these nerve fibers reduced BP in rats. However, there is no technique described to localize and stimulate these fibers inside the VN without inadvertent stimulation of non-baroreceptive fibers causing side effects like bradycardia and bradypnea. Approach. We present a novel method for selective VN stimulation to reduce BP without the aforementioned side effects. Baroreceptor compound activity of rat VN (n = 5) was localized using a multichannel cuff electrode, true tripolar recording and a coherent averaging algorithm triggered by BP or electrocardiogram. Main results. Tripolar stimulation over electrodes near the barofibers reduced the BP without triggering significant bradycardia and bradypnea. The BP drop was adjusted to 60% of the initial value by varying the stimulation pulse width and duration, and lasted up to five times longer than the stimulation. Significance. The presented method is robust to impedance changes, independent of the electrode's relative position, does not compromise the nerve and can run on implantable, ultra-low power signal processors.

Comparative Assessment of the Effects of Three Local Anesthetics: Lidocaine, Prilocaine, and Mepivacaine on Blood Pressure Changes in Patients with Controlled Hypertension.

PubMed

Hashemi, Seyyed Hamed Jalalian; Ladez, Shamsodin Rigi; Moghadam, Somaye Ansari

2016-10-01

Given large number of patients with hypertension attending dental clinics and the profound effects of local anesthetics containing vasoconstrictors, this study aimed to compare the effects of lidocaine 2% + epinephrine, prilocaine 3% + felypressin0.03, and mepivacaine 3% on blood pressure changes. The current study was carried out from May 2014 to February 2015.Patients with controlled hypertension (systolic blood pressure<159.94 mmHg before the injection) who attended Zahedan dental school (Zahedan , Iran) for the extraction of a mandibular tooth were selected and randomly allocated to three groups of 20. Groups 1-3 received lidocaine 2% + epinephrine, prilocaine 3% + felypressin 0.03 units, and mepivacaine3%, respectively. Patients were only included if they were injected with a maximum of two 1.8 ml cartridges (3.6 ml) for tooth extraction (maximum epinephrine dose of 0.04 mg was maintained in systemic patients).The collected data were analyzed using the analysis of variance (ANOVA) in SPSS 19.0. (SPSS Inc., Chicago, IL, USA)RESULTS: No significant differences were observed between the systolic and diastolic blood pressure of the three groups. The three evaluated local anesthetic solutions had similar effects in patients with controlled hypertension. While no significant changes in blood pressure were observed in three groups, all dental procedures on the mentioned group of patients have to be performed under careful monitoring and aspiration. Moreover, the maximum epinephrine dose (0.04mg) should never be exceeded in these patients.

Adaptive molecular evolution of the two-pore channel 1 gene TPC1 in the karst-adapted genus Primulina (Gesneriaceae)

PubMed Central

Tao, Junjie; Feng, Chao; Ai, Bin; Kang, Ming

2016-01-01

Background and Aims Limestone karst areas possess high floral diversity and endemism. The genus Primulina, which contributes to the unique calcicole flora, has high species richness and exhibit specific soil-based habitat associations that are mainly distributed on calcareous karst soils. The adaptive molecular evolutionary mechanism of the genus to karst calcium-rich environments is still not well understood. The Ca2+-permeable channel TPC1 was used in this study to test whether its gene is involved in the local adaptation of Primulina to karst high-calcium soil environments. Methods Specific amplification and sequencing primers were designed and used to amplify the full-length coding sequences of TPC1 from cDNA of 76 Primulina species. The sequence alignment without recombination and the corresponding reconstructed phylogeny tree were used in molecular evolutionary analyses at the nucleic acid level and amino acid level, respectively. Finally, the identified sites under positive selection were labelled on the predicted secondary structure of TPC1. Key Results Seventy-six full-length coding sequences of Primulina TPC1 were obtained. The length of the sequences varied between 2220 and 2286 bp and the insertion/deletion was located at the 5′ end of the sequences. No signal of substitution saturation was detected in the sequences, while significant recombination breakpoints were detected. The molecular evolutionary analyses showed that TPC1 was dominated by purifying selection and the selective pressures were not significantly different among species lineages. However, significant signals of positive selection were detected at both TPC1 codon level and amino acid level, and five sites under positive selective pressure were identified by at least three different methods. Conclusions The Ca2+-permeable channel TPC1 may be involved in the local adaptation of Primulina to karst Ca2+-rich environments. Different species lineages suffered similar selective pressure associated with calcium in karst environments, and episodic diversifying selection at a few sites may play a major role in the molecular evolution of Primulina TPC1. PMID:27582362

An investigation to determine the static pressure distribution of the 0.00548 scale shuttle solid rocket booster (MSFC model number 468) during reentry in the NASA/MSFC 14 inch trisonic wind tunnel (SA28F)

NASA Technical Reports Server (NTRS)

Braddock, W. F.; Streby, G. D.

1977-01-01

The results of a pressure test of a .00548 scale 146 inch Space Shuttle Solid Rocket Booster (SRB) with and without protuberances, conducted in a 14 x 14 inch trisonic wind tunnel are presented. Static pressure distributions for the SRB at reentry attitudes and flight conditions were obtained. Local longitudinal and ring pressure distributions are presented in tabulated form. Integration of the pressure data was performed. The test was conducted at Mach numbers of 0.40 to 4.45 over an angle of attack range from 60 to 185 degrees. Roll angles of 0, 45, 90 and 315 degrees were investigated. Reynolds numbers per foot varied for selected Mach numbers.

Study and design of cryogenic propellant acquisition systems. Volume 1: Design studies

NASA Technical Reports Server (NTRS)

Burge, G. W.; Blackmon, J. B.

1973-01-01

An in-depth study and selection of practical propellant surface tension acquisition system designs for two specific future cryogenic space vehicles, an advanced cryogenic space shuttle auxiliary propulsion system and an advanced space propulsion module is reported. A supporting laboratory scale experimental program was also conducted to provide design information critical to concept finalization and selection. Designs using localized pressure isolated surface tension screen devices were selected for each application and preliminary designs were generated. Based on these designs, large scale acquisition prototype hardware was designed and fabricated to be compatible with available NASA-MSFC feed system hardware.

An experimental study of the effects of bodyside compression on forward swept sidewall compression inlets ingesting a turbulent boundary layer

NASA Technical Reports Server (NTRS)

Rodi, Patrick E.

1993-01-01

Forward swept sidewall compression inlets have been tested in the Mach 4 Blowdown Facility at the NASA Langley Research Center to study the effects of bodyside compression surfaces on inlet performance in the presence of an incoming turbulent boundary layer. The measurements include mass flow capture and mean surface pressure distributions obtained during simulated combustion pressure increases downstream of the inlet. The kerosene-lampblack surface tracer technique has been used to obtain patterns of the local wall shear stress direction. Inlet performance is evaluated using starting and unstarting characteristics, mass capture, mean surface pressure distributions and permissible back pressure limits. The results indicate that inlet performance can be improved with selected bodyside compression surfaces placed between the inlet sidewalls.

Instrumentation

for Examining

Microbial Response

to Changes In Environmental Pressures

NASA Astrophysics Data System (ADS)

Blaich, J.; Storrs, A.; Wang, J.; Ouandji, C.; Arismendi, D.; Hernandez, J.; Sardesh, N.; Ibanez, C. R.; Owyang, S.; Gentry, D.

2016-12-01

The Automated Adaptive Directed Evolution Chamber (AADEC) is a device that allows operators to generate a micro-scale analog of real world systems that can be used to model the local-scale effects of climate change on microbial ecosystems. The AADEC uses an artificial environment to expose cultures of micro-organisms to environmental pressures, such as UV-C radiation, chemical toxins, and temperature. The AADEC autonomously exposes micro-organisms to slection pressures. This improves upon standard manual laboratory techniques: the process can take place over a longer period of time, involve more stressors, implement real-time adjustments based on the state of the population, and minimize the risk of contamination. We currently use UV-C radiation as the main selection pressure, UV-C is well studied both for its cell and DNA damaging effects as a type of selection pressure and for its related effectiveness as a mutagen; having these functions united makes it a good choice for a proof of concept. The AADEC roadmap includes expansion to different selection pressures, including heavy metal toxicity, temperature, and other forms of radiation. The AADEC uses closed-loop control to feedback the current state of the culture to the AADEC controller that modifies selection pressure intensity during experimentation, in this case culture density and growth rate. Culture density and growth rate are determined by measuring the optical density of the culture using 600 nm light. An array of 600 nm LEDs illuminate the culture and photodiodes are used to measure the shadow on the opposite side of the chamber. Previous experiments showed that we can produce a million fold increase to UV-C radiation over seven iterations. The most recent implements a microfluidic system that can expose cultures to multiple different selection pressures, perform non-survival based selection, and autonomously perform hundreds of exposure cycles. A scalable pump system gives the ability to pump in various different growth media to individual cultures and introduce chemical toxins during experimentation; AADEC can perform freeze and thaw cycles. We improved our baseline characterization by building a custom UV-C exposure hood, a shutter operates on a preset timer allowing the user to set exposure intensity consistently for multiple iterations.

Isolating causal pathways between flow and fish in the regulated river hierarchy

Treesearch

Ryan McManamay; Donald J. Orth; Charles A. Dolloff; David C. Mathews

2015-01-01

Unregulated river systems are organized in a hierarchy in which large scale factors (i.e. landscape and segment scales) influence local habitats (i.e. reach, meso- and microhabitat scales), and both differentially exert selective pressures on biota. Dams, however, create discontinua in these processes and change the hierarchical structure. We examined the relative...

Complex Patterns of Local Adaptation in Teosinte

PubMed Central

Pyhäjärvi, Tanja; Hufford, Matthew B.; Mezmouk, Sofiane; Ross-Ibarra, Jeffrey

2013-01-01

Populations of widely distributed species encounter and must adapt to local environmental conditions. However, comprehensive characterization of the genetic basis of adaptation is demanding, requiring genome-wide genotype data, multiple sampled populations, and an understanding of population structure and potential selection pressures. Here, we used single-nucleotide polymorphism genotyping and data on numerous environmental variables to describe the genetic basis of local adaptation in 21 populations of teosinte, the wild ancestor of maize. We found complex hierarchical genetic structure created by altitude, dispersal events, and admixture among subspecies, which complicated identification of locally beneficial alleles. Patterns of linkage disequilibrium revealed four large putative inversion polymorphisms showing clinal patterns of frequency. Population differentiation and environmental correlations suggest that both inversions and intergenic polymorphisms are involved in local adaptation. PMID:23902747

Composite selection signals can localize the trait specific genomic regions in multi-breed populations of cattle and sheep

PubMed Central

2014-01-01

Background Discerning the traits evolving under neutral conditions from those traits evolving rapidly because of various selection pressures is a great challenge. We propose a new method, composite selection signals (CSS), which unifies the multiple pieces of selection evidence from the rank distribution of its diverse constituent tests. The extreme CSS scores capture highly differentiated loci and underlying common variants hauling excess haplotype homozygosity in the samples of a target population. Results The data on high-density genotypes were analyzed for evidence of an association with either polledness or double muscling in various cohorts of cattle and sheep. In cattle, extreme CSS scores were found in the candidate regions on autosome BTA-1 and BTA-2, flanking the POLL locus and MSTN gene, for polledness and double muscling, respectively. In sheep, the regions with extreme scores were localized on autosome OAR-2 harbouring the MSTN gene for double muscling and on OAR-10 harbouring the RXFP2 gene for polledness. In comparison to the constituent tests, there was a partial agreement between the signals at the four candidate loci; however, they consistently identified additional genomic regions harbouring no known genes. Persuasively, our list of all the additional significant CSS regions contains genes that have been successfully implicated to secondary phenotypic diversity among several subpopulations in our data. For example, the method identified a strong selection signature for stature in cattle capturing selective sweeps harbouring UQCC-GDF5 and PLAG1-CHCHD7 gene regions on BTA-13 and BTA-14, respectively. Both gene pairs have been previously associated with height in humans, while PLAG1-CHCHD7 has also been reported for stature in cattle. In the additional analysis, CSS identified significant regions harbouring multiple genes for various traits under selection in European cattle including polledness, adaptation, metabolism, growth rate, stature, immunity, reproduction traits and some other candidate genes for dairy and beef production. Conclusions CSS successfully localized the candidate regions in validation datasets as well as identified previously known and novel regions for various traits experiencing selection pressure. Together, the results demonstrate the utility of CSS by its improved power, reduced false positives and high-resolution of selection signals as compared to individual constituent tests. PMID:24636660

TMEM16A Channels Contribute to the Myogenic Response in Cerebral Arteries

PubMed Central

Bulley, Simon; Neeb, Zachary P.; Burris, Sarah K.; Bannister, John P.; Thomas-Gatewood, Candice M.; Jangsangthong, Wanchana; Jaggar, Jonathan H.

2013-01-01

Rationale Pressure-induced arterial depolarization and constriction (the myogenic response), is a smooth muscle cell (myocyte)-specific mechanism that controls regional organ blood flow and systemic blood pressure. Several different non-selective cation channels contribute to pressure-induced depolarization, but signaling mechanisms involved are unclear. Similarly uncertain is the contribution of anion channels to the myogenic response and physiological functions and mechanisms of regulation of recently discovered transmembrane 16A (TMEM16A) chloride (Cl−) channels in arterial myocytes. Objective Investigate the hypothesis that myocyte TMEM16A channels control membrane potential and contractility and contribute to the myogenic response in cerebral arteries. Methods and Results Cell swelling induced by hyposmotic bath solution stimulated Cl− currents in arterial myocytes that were blocked by TMEM16A channel inhibitory antibodies, RNAi-mediated selective TMEM16A channel knockdown, removal of extracellular calcium (Ca2+), replacement of intracellular EGTA with BAPTA, a fast Ca2+ chelator, and Gd3+ and SKF-96365, non-selective cation channel blockers. In contrast, nimodipine, a voltage-dependent Ca2+ channel inhibitor, or thapsigargin, which depletes intracellular Ca2+ stores, did not alter swelling-activated TMEM16A currents. Pressure (−40 mmHg)-induced membrane stretch activated ion channels in arterial myocyte cell-attached patches that were inhibited by TMEM16A antibodies and were of similar amplitude to recombinant TMEM16A channels. TMEM16A knockdown reduced intravascular pressure-induced depolarization and vasoconstriction, but did not alter depolarization (60 mmol/L K+)-induced vasoconstriction. Conclusions Membrane stretch activates arterial myocyte TMEM16A channels, leading to membrane depolarization and vasoconstriction. Data also provide a mechanism by which a local Ca2+ signal generated by non-selective cation channels stimulates TMEM16A channels to induce myogenic constriction. PMID:22872152

Motion-based signaling in sympatric species of Australian agamid lizards.

PubMed

Ramos, Jose A; Peters, Richard A

2017-08-01

Signaling species occurring in sympatry are often exposed to similar environmental constraints, so similar adaptations to enhance signal efficacy are expected. However, potentially opposing selective pressures might be present to ensure species recognition. Here, we analyzed the movement-based signals of two pairs of sympatric lizard species to consider how reliable communication is maintained while avoiding misidentification. Our novel approach allows us to quantify signal contrast with plant motion noise at any site we measure, including those utilized by other species. Ctenophorus caudicinctus and Gowidon longirostris differed in display complexity and motor pattern use. They also differed in overall morphology, but their signal contrast scores are strikingly similar. These results demonstrate similar adaptations to their shared environment while maintaining species recognition cues. In contrast, Ctenophorus fordi and Ctenophorus pictus are much closer in appearance, but C. pictus produces considerably higher signal contrast scores, which we suggest is attributable to the absence of territoriality in C. fordi. Taken together, our data provide evidence for adaptation to the local environment in movement-based signals, while also meeting species recognition requirements, but the selective pressure to deal with local conditions is mediated by signal function.

Advancing a smart air cushion system for preventing pressure ulcers using projection Moiré for large deformation measurements

NASA Astrophysics Data System (ADS)

Cheng, Sheng-Lin; Tsai, Tsung-Heng; Lee, Carina Jean-Tien; Hsu, Yu-Hsiang; Lee, Chih-Kung

2016-03-01

A pressure ulcer is one of the most important concerns for wheelchair bound patients with spinal cord injuries. A pressure ulcer is a localized injury near the buttocks that bear ischial tuberosity oppression over a long period of time. Due to elevated compression to blood vessels, the surrounding tissues suffer from a lack of oxygen and nutrition. The ulcers eventually lead to skin damage followed by tissue necrosis. The current medical strategy is to minimize the occurrence of pressure ulcers by regularly helping patients change their posture. However, these methods do not always work effectively or well. As a solution to fundamentally prevent pressure ulcers, a smart air cushion system was developed to detect and control pressure actively. The air cushion works by automatically adjusting a patient's sitting posture to effectively relieve the buttock pressure. To analyze the correlation between the dynamic pressure profiles of an air cell with a patient's weight, a projection Moiré system was adopted to measure the deformation of an air cell and its associated stress distribution. Combining a full-field deformation imaging with air pressure measured within an air cell, the patient's weight and the stress distribution can be simultaneously obtained. By integrating a full-field optical metrology with a time varying pressure sensor output coupled with different active air control algorithms for various designs, we can tailor the ratio of the air cells. Our preliminary data suggests that this newly developed smart air cushion has the potential to selectively reduce localized compression on the tissues at the buttocks. Furthermore, it can take a patient's weight which is an additional benefit so that medical personnel can reference it to prescribe the correct drug dosages.

Evolutionary dynamics of the leaf phenological cycle in an oak metapopulation along an elevation gradient.

PubMed

Firmat, C; Delzon, S; Louvet, J-M; Parmentier, J; Kremer, A

2017-12-01

It has been predicted that environmental changes will radically alter the selective pressures on phenological traits. Long-lived species, such as trees, will be particularly affected, as they may need to undergo major adaptive change over only one or a few generations. The traits describing the annual life cycle of trees are generally highly evolvable, but nothing is known about the strength of their genetic correlations. Tight correlations can impose strong evolutionary constraints, potentially hampering the adaptation of multivariate phenological phenotypes. In this study, we investigated the evolutionary, genetic and environmental components of the timing of leaf unfolding and senescence within an oak metapopulation along an elevation gradient. Population divergence, estimated from in situ and common-garden data, was compared to expectations under neutral evolution, based on microsatellite markers. This approach made it possible (1) to evaluate the influence of genetic correlation on multivariate local adaptation to elevation and (2) to identify traits probably exposed to past selective pressures due to the colder climate at high elevation. The genetic correlation was positive but very weak, indicating that genetic constraints did not shape the local adaptation pattern for leaf phenology. Both spring and fall (leaf unfolding and senescence, respectively) phenology timings were involved in local adaptation, but leaf unfolding was probably the trait most exposed to climate change-induced selection. Our data indicated that genetic variation makes a much smaller contribution to adaptation than the considerable plastic variation displayed by a tree during its lifetime. The evolutionary potential of leaf phenology is, therefore, probably not the most critical aspect for short-term population survival in a changing climate. © 2017 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2017 European Society For Evolutionary Biology.

Excavating and loading equipment for peat mining

NASA Astrophysics Data System (ADS)

Mikhailov, A. V.; Zhigulskaya, A. I.; Yakonovskaya, T. B.

2017-10-01

Recently, the issues of sustainable development of Russian regions, related to ensuring energy security, are more urgent than ever. To achieve sustainable development, an integrated approach to the use of local natural resources is needed. Practically in all north regions of the Russian Federation, peat as a local natural resource is widespread, which has a practical application in the area of housing services. The paper presents the evaluation of technologies for open-pit peat mining, as well as analysis of technological equipment for peat production. Special attention is paid to a question of peat materials excavating and loading. The problem of equipment selection in a peat surface mine is complex. Many features, restrictions and criteria need to be considered. Use of low and ultra-low ground pressure excavators and low ground pressure front-end loaders with full-range tires to provide the necessary floatation in the peat bog environment is offered.

Health plan competition in local markets.

PubMed

Grossman, J M

2000-04-01

To examine the structure of local health insurance markets and the strategies health plans were using to respond to competitive pressures in local markets in 1996/1997. Community Tracking Study site visits conducted between May 1996 and April 1997 in 12 U.S. markets selected to be nationally representative. In each site, 36 to 60 interviews on local health system change were conducted with healthcare industry informants representing health plans, providers, and purchasers. Relevant data for this article were abstracted from standardized protocols administered to multiple respondents in each site. Although the competitive threat from national plans was pervasive, local plans in most sites continued to retain strong, often dominant, positions in historically concentrated markets. In all sites, in response to purchaser pressures for stable premiums and provider choice, and the threat of entry and to plans were using three strategies to increase market share and market power: (1) consolidation/geographic expansion, (2) price competition, and (3) product line/segment diversification that focused on broad networks and open-access products. In most markets, in response to the demand for provider choice, the trend was away from ownership and exclusive arrangements with providers. Although local plans were moving to become full-service regional players, there was uncertainty about the abilities of all plans to sustain growth strategies at the expense of margins and organizational stability, and to effectively manage care with broad networks.

Tracking sensitive source areas of different weather pollution types using GRAPES-CUACE adjoint model

NASA Astrophysics Data System (ADS)

Wang, Chao; An, Xingqin; Zhai, Shixian; Hou, Qing; Sun, Zhaobin

2018-02-01

In this study, the sustained pollution processes were selected during which daily PM2.5 concentration exceeded 75 μg/m3 for three days continuously based on the hourly data of Beijing observation sites from July 2012 to December 2015. Using the China Meteorological Administration (CMA) MICAPS meteorological processing system, synoptic situation during PM2.5 pollution processes was classified into five weather types: low pressure and weak high pressure alternating control, weak high pressure, low pressure control, high rear, and uniform pressure field. Then, we chose the representative pollution cases corresponding to each type, adopted the GRAPES-CUACE adjoint model tracking the sensitive source areas of the five types, and analyzed the critical discharge periods of Beijing and neighboring provinces as well as their contribution to the PM2.5 peak concentration in Beijing. The results showed that the local source plays the main theme in the 30 h before the objective time, and prior to 72 h before the objective time contribution of local sources for the five pollution types are 37.5%, 25.0%, 39.4%, 31.2%, and 42.4%, respectively; the Hebei source contributes constantly in the 57 h ahead of the objective time with the contribution proportion ranging from 37% to 64%; the contribution period and rate of Tianjin and Shanxi sources are shorter and smaller. Based on the adjoint sensitivity analysis, we further discussed the effect of emission reduction control measures in different types, finding that the effect of local source reduction in the first 20 h of the objective time is better, and if the local source is reduced 50% within 72 h before the objective time, the decline rates of PM2.5 in the five types are 11.6%, 9.4%, 13.8%, 9.9% and 15.2% respectively. And the reduction effect of the neighboring sources is better within the 3-57 h before the objective time.

Pathways to exotic metastable silicon allotropes

DOE PAGES

Haberl, Bianca; Strobel, Timothy A.; Bradby, Jodie E.

2016-09-27

The Group 14 element silicon possesses a complex free-energy landscape with many (local) minima, allowing for the formation of a variety of unusual structures, some of which may be stabilized at ambient conditions. Such exotic silicon allotropes represent a significant opportunity to address the ever-increasing demand for novel materials with tailored functionality since these exotic forms are expected to exhibit superlative properties including optimized band gaps for solar power conversion. The application of pressure is a well-recognized and uniquely powerful method to access exotic states of silicon since it promotes large changes to atomic bonding. Conventional high-pressure syntheses, however, lackmore » the capability to access many of these local minima and only four forms of exotic silicon allotropes have been recovered over the last 50 years. However, more recently, signifi- cant advances in high pressure methodologies and the use of novel precursor materials have yielded at least three more recoverable exotic Si structures. This review aims to give an overview of these innovative methods of high-pressure application and precursor selection and the recent discoveries of new Si allotropes. The background context of the conventional pressure methods and multitude of predicted new phases are also provided. Furthermore, this review also offers a perspective for possible access to many further exotic functional allotropes not only of silicon but also of other materials, in a technologically feasible manner« less

Treatment of anismus in intractable constipation with botulinum A toxin.

PubMed

Hallan, R I; Williams, N S; Melling, J; Waldron, D J; Womack, N R; Morrison, J F

1988-09-24

In seven patients with anismus the striated sphincter muscle complex was selectively weakened by local injection of Clostridium botulinum type A toxin. Symptom scores improved significantly and correlated with a significant reduction in the maximum voluntary and canal squeeze pressure and a significant increase in the anorectal angle on straining. Botulinum A toxin seems to be promising treatment for some patients with anismus.

Genome-wide scans for loci under selection in humans

PubMed Central

2005-01-01

Natural selection, which can be defined as the differential contribution of genetic variants to future generations, is the driving force of Darwinian evolution. Identifying regions of the human genome that have been targets of natural selection is an important step in clarifying human evolutionary history and understanding how genetic variation results in phenotypic diversity, it may also facilitate the search for complex disease genes. Technological advances in high-throughput DNA sequencing and single nucleotide polymorphism genotyping have enabled several genome-wide scans of natural selection to be undertaken. Here, some of the observations that are beginning to emerge from these studies will be reviewed, including evidence for geographically restricted selective pressures (ie local adaptation) and a relationship between genes subject to natural selection and human disease. In addition, the paper will highlight several important problems that need to be addressed in future genome-wide studies of natural selection. PMID:16004726

[Appropriate dust control measures for jade carving operations].

PubMed

Liu, Jiang; Wang, Qiushui; Liu, Guangquan

2002-12-01

To provide the appropriate dust control measures for jade carving operations. Dust concentrations in the workplace were measured according to GB/T 5748-85. Ventilation system of dust control were measured according to GB/T 16157-1996. Dust particle size distributions for different sources and particle size fraction collecting efficiencies of the dust collectors were measured with WY-1 in-stack 7 stage cascade impactors. On the basis of adopting wet process in the carving operations, local exhaust ventilation system for dust control was installed, which included: the special designed slot exhaust hoods with hood face velocity of 2.5 m/s and exhaust volume of 600 m3/h. The pipe sizes were determined according to the air volume passing through the pipe and the reasonable air velocities. Impinging scrubber or bag filter dust collector were selected to treat the dust laden air from the local exhaust ventilation system, which gave a total collecting efficiency of 97% for impinging scrubber and 98% for bag filter; The type of fan and its size were selected according to the total air volume of the ventilation system and maximum total pressure needed for the longest pipe line plus the pressure drop of the dust collector. Practical application showed that, after installation and use of the appropriate dust control measures, the dust concentrations in the workplaces could meet or nearly meet the national hygienic standard and the dust laden air at the local exhaust ventilation system could meet the national emission standard.

The role of standing variation in geographic convergent adaptation

PubMed Central

Ralph, Peter L.; Coop, Graham

2016-01-01

The extent to which populations experiencing shared selective pressures adapt through a shared genetic response is relevant to many questions in evolutionary biology. In a number of well studied traits and species, it appears that convergent evolution within species is common. In this paper, we explore how standing, genetic variation contributes to convergent genetic responses in a geographically spread population, extending our previous work on the topic. Geographically limited dispersal slows the spread of each selected allele, hence allowing other alleles – newly arisen mutants or present as standing variation – to spread before any one comes to dominate the population. When such alleles meet, their progress is substantially slowed – if the alleles are selectively equivalent, they mix slowly, dividing the species range into a random tessellation, which can be well understood by analogy to a Poisson process model of crystallization. In this framework, we derive the geographic scale over which a typical allele is expected to dominate, the time it takes the species to adapt as a whole, and the proportion of adaptive alleles that arise from standing variation. Finally, we explore how negative pleiotropic effects of alleles before an environment change can bias the subset of alleles that contribute to the species’ adaptive response. We apply the results to the many geographically localized G6PD deficiency alleles thought to confer resistance to malaria, where the large mutational target size makes it a likely candidate for adaptation from standing variation, despite the selective cost of G6PD deficiency alleles in the absence of malaria. We find the numbers and geographic spread of these alleles matches our predictions reasonably well, consistent with the view that they arose from a combination of standing variation and new mutations since the advent of malaria. Our results suggest that much of adaptation may be geographically local even when selection pressures are homogeneous. Therefore, we argue that caution must be exercised when arguing that strongly geographically restricted alleles are necessarily the outcome of local adaptation. We close by discussing the implications of these results for ideas of species coherence and the nature of divergence between species. PMID:26656217

Local cerebral hypothermia induced by selective infusion of cold lactated ringer's: a feasibility study in rhesus monkeys.

PubMed

Wang, Bincheng; Wu, Di; Dornbos Iii, David; Shi, Jingfei; Ma, Yanhui; Zhang, Mo; Liu, Yumei; Chen, Jian; Ding, Yuchuan; Luo, Yinghao; Ji, Xunming

2016-06-01

Hypothermia has shown promise as a neuroprotective strategy for stroke. The use of whole body hypothermia has limited clinical utility due to many severe side effects. Selective brain cooling, or local brain hypothermia, has been previously proposed as an alternative treatment strategy. This study investigated the safety, feasibility, and efficacy of selective brain hypothermia induced by local infusion of ice-cold lactated Ringer's solution in rhesus monkeys. Eight male rhesus monkeys were used in this study. Brain temperature in the territory supplied by middle cerebral artery (MCA) was reduced by infusing 100 mL of ice-cold (0 °C) lactated Ringer's solution over 20 min via a micro-catheter placed in the proximal MCA (n = 4). Vital signs and the temperature of the brain and rectum were monitored before and after infusion. Transcranial Doppler, Magnetic resonance imaging (MRI), and digital subtraction angiography (DSA) were used to evaluate cerebral blood flow, cerebrovascular reactivity (CVR), cerebral edema, and vasospasm. Another cohort of rhesus monkeys (n = 4) were used as systemic cooling controls. Oxygen saturation, blood pressure, heart rate, and hematologic analysis of the two groups remained within the normal range after infusion. Mild cerebral hypothermia (<35 °C) was achieved in 10 min (0.3 °C/min) and was maintained for 20 min in local cortex and striatum following local infusion. The average lowest cerebral temperature in the locally cooled animals was 33.9 ± 0.3 °C in the striatum following 20-min infusion. This was not observed in animals cooled by systemic infusion. The decreases in the rectal temperature for local and systemic infusion were 0.5 ± 0.2 °C and 0.5 ± 0.3 °C, respectively. Selective brain cooling did not cause any cerebral edema as determined by MRI or vasospasm in the perfused vessel based on DSA. Selective cerebral hypothermia did not significantly alter CVR. Local infusion of ice-cold lactated Ringer's solution via micro-catheter is a safe and effective method for selective cerebral hypothermia. This cooling method could potentially be developed as a new treatment in acute ischemic stroke.

Evaluation of coated columbium alloy heat shields for space shuttle thermal protection system application. Volume 2, phase 2: Subsize heat shield and small size TPS evaluation

NASA Technical Reports Server (NTRS)

Black, W. E.

1973-01-01

Initially a trade study was conducted of seven heat shield configurations. These were evaluated for structural reliability, fabricability, weight, inspectability, and refurbishability. Two concepts, a tee-stiffened and an open corrugation, were selected as offering the most potential for system success. Fourteen subsize heat shields of a full scale section were fabricated from C-129Y and Cb-752 and silicide coated with R-512E. These subsize panels were subjected to a simulated flight profile representing temperature, local surface pressures, and applied pressure differential loads. All corrugated panels of both alloys sustained 100 cycles without structural or coating failure. All Cb-752/R-512E panels performed well with one panel being successfully repaired after 66 cycles and completing 100 cycles. As a result of this evaluating the Cb-752/R-512E system was selected for hardware application during the subsequent phases. In addition, the tee-stiffened configuration was selected for further development and application in Phase III. This selection was based on an overall assessment of relative weight, cost, and structural performance of the tee-stiffened and open corrugation TPS.

Effect of local cooling on pro-inflammatory cytokines and blood flow of the skin under surface pressure in rats: feasibility study.

PubMed

Lee, Bernard; Benyajati, Siribhinya; Woods, Jeffrey A; Jan, Yih-Kuen

2014-05-01

The primary purpose of this feasibility study was to establish a correlation between pro-inflammatory cytokine accumulation and severity of tissue damage during local pressure with various temperatures. The secondary purpose was to compare skin blood flow patterns for assessing the efficacy of local cooling on reducing skin ischemia under surface pressure. Eight Sprague-Dawley rats were assigned to two protocols, including pressure with local cooling (Δt = -10 °C) and pressure with local heating (Δt = 10 °C). Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin perfusion quantified by laser Doppler flowmetry and TNF-∗ and IL-1β levels were measured. Our results showed that TNF-α concentrations were increased more significantly with local heating than with local cooling under pressure whereas IL-1β did not change. Our results support the notion that weight bearing soft tissue damage may be reduced through temperature modulation and that non-invasive perfusion measurements using laser Doppler flowmetry may be capable of assessing viability. Furthermore, these results show that perfusion response to loading pressure may be correlated with changes in local pro-inflammatory cytokines. These relationships may be relevant for the development of cooling technologies for reducing risk of pressure ulcers. Copyright © 2014 Tissue Viability Society. Published by Elsevier Ltd. All rights reserved.

Earliest effects of sudden occlusions on pressure profiles in selected locations of the human systemic arterial system

NASA Astrophysics Data System (ADS)

Majka, Marcin; Gadda, Giacomo; Taibi, Angelo; Gałązka, Mirosław; Zieliński, Piotr

2017-03-01

We have developed a numerical simulation method for predicting the time dependence (wave form) of pressure at any location in the systemic arterial system in humans. The method uses the matlab-Simulink environment. The input data include explicitly the geometry of the arterial tree, treated up to an arbitrary bifurcation level, and the elastic properties of arteries as well as rheological parameters of blood. Thus, the impact of anatomic details of an individual subject can be studied. The method is applied here to reveal the earliest stages of mechanical reaction of the pressure profiles to sudden local blockages (thromboses or embolisms) of selected arteries. The results obtained with a purely passive model provide reference data indispensable for studies of longer-term effects due to neural and humoral mechanisms. The reliability of the results has been checked by comparison of two available sets of anatomic, elastic, and rheological data involving (i) 55 and (ii) 138 arterial segments. The remaining arteries have been replaced with the appropriate resistive elements. Both models are efficient in predicting an overall shift of pressure, whereas the accuracy of the 55-segment model in reproducing the detailed wave forms and stabilization times turns out dependent on the location of the blockage and the observation point.

Adaptations to local environments in modern human populations.

PubMed

Jeong, Choongwon; Di Rienzo, Anna

2014-12-01

After leaving sub-Saharan Africa around 50000-100000 years ago, anatomically modern humans have quickly occupied extremely diverse environments. Human populations were exposed to further environmental changes resulting from cultural innovations, such as the spread of farming, which gave rise to new selective pressures related to pathogen exposures and dietary shifts. In addition to changing the frequency of individual adaptive alleles, natural selection may also shape the overall genetic architecture of adaptive traits. Here, we review recent advances in understanding the genetic architecture of adaptive human phenotypes based on insights from the studies of lactase persistence, skin pigmentation and high-altitude adaptation. These adaptations evolved in parallel in multiple human populations, providing a chance to investigate independent realizations of the evolutionary process. We suggest that the outcome of adaptive evolution is often highly variable even under similar selective pressures. Finally, we highlight a growing need for detecting adaptations that did not follow the classical sweep model and for incorporating new sources of genetic evidence such as information from ancient DNA. Copyright © 2014 Elsevier Ltd. All rights reserved.

Materials for a Stirling engine heater head

NASA Technical Reports Server (NTRS)

Noble, J. E.; Lehmann, G. A.; Emigh, S. G.

1990-01-01

Work done on the 25-kW advanced Stirling conversion system (ASCS) terrestrial solar program in establishing criteria and selecting materials for the engine heater head and heater tubes is described. Various mechanisms contributing to incompatibility between materials are identified and discussed. Large thermal gradients, coupled with requirements for long life (60,000 h at temperature) and a large number of heatup and cooldown cycles (20,000) drive the design from a structural standpoint. The pressurized cylinder is checked for creep rupture, localized yielding, reverse plasticity, creep and fatigue damage, and creep ratcheting, in addition to the basic requirements for bust and proof pressure. In general, creep rupture and creep and fatigue interaction are the dominant factors in the design. A wide range of materials for the heater head and tubes was evaluated. Factors involved in the assessment were strength and effect on engine efficiency, reliability, and cost. A preliminary selection of Inconel 713LC for the heater head is based on acceptable structural properties but driven mainly by low cost. The criteria for failure, the structural analysis, and the material characteristics with basis for selection are discussed.

A Proposed Dynamic Pressure and Temperature Primary Standard

PubMed Central

Rosasco, Gregory J.; Bean, Vern E.; Hurst, Wilbur S.

1990-01-01

Diatomic gas molecules have a fundamental vibrational motion whose frequency is affected by pressure in a simple way. In addition, these molecules have well defined rotational energy levels whose populations provide a reliable measure of the thermodynamic temperature. Since information concerning the frequency of vibration and the relative populations can be determined by laser spectroscopy, the gas molecules themselves can serve as sensors of pressure and temperature. Through measurements under static conditions, the pressure and temperature dependence of the spectra of selected molecules is now understood. As the time required for the spectroscopic measurement can be reduced to nanoseconds, the diatomic gas molecule is an excellent candidate for a dynamic pressure/temperature primary standard. The temporal response in this case will be limited by the equilibration time for the molecules to respond to changes in local thermodynamic variables. Preliminary feasibility studies suggest that by using coherent anti-Stokes Raman spectroscopy we will be able to measure dynamic pressure up to 108 Pa and dynamic temperature up to 1500 K with an uncertainty of 5%. PMID:28179756

Myocardial pressure overload induces systemic inflammation through endothelial cell IL-33

PubMed Central

Chen, Wei-Yu; Hong, Jaewoo; Gannon, Joseph; Kakkar, Rahul; Lee, Richard T.

2015-01-01

Hypertension increases the pressure load on the heart and is associated with a poorly understood chronic systemic inflammatory state. Interleukin 33 (IL-33) binds to membrane-bound ST2 (ST2L) and has antihypertrophic and antifibrotic effects in the myocardium. In contrast, soluble ST2 appears to act as a decoy receptor for IL-33, blocking myocardial and vascular benefits, and is a prognostic biomarker in patients with cardiovascular diseases. Here we report that a highly local intramyocardial IL-33/ST2 conversation regulates the heart’s response to pressure overload. Either endothelial-specific deletion of IL33 or cardiomyocyte-specific deletion of ST2 exacerbated cardiac hypertrophy with pressure overload. Furthermore, pressure overload induced systemic circulating IL-33 as well as systemic circulating IL-13 and TGF-beta1; this was abolished by endothelial-specific deletion of IL33 but not by cardiomyocyte-specific deletion of IL33. Our study reveals that endothelial cell secretion of IL-33 is crucial for translating myocardial pressure overload into a selective systemic inflammatory response. PMID:25941360

Microgeographic patterns of genetic divergence and adaptation across environmental gradients in Boechera stricta (Brassicaceae)

PubMed Central

Anderson, Jill T.; Perera, Nadeesha; Chowdhury, Bashira; Mitchell-Olds, Thomas

2015-01-01

Abiotic and biotic conditions often vary continuously across the landscape, imposing divergent selection on local populations. We used a provenance trial approach to examine microgeographic variation in local adaptation in Boechera stricta (Brassicaceae), a perennial forb native to the Rocky Mountains. In montane ecosystems, environmental conditions change considerably over short spatial scales, such that neighboring populations can be subject to different selective pressures. Using accessions from southern (Colorado) and northern (Idaho) populations, we characterized spatial variation in genetic similarity via microsatellite markers. We then transplanted genotypes from multiple local populations into common gardens in both regions. Continuous variation in local adaptation emerged for several components of fitness. In Idaho, genotypes from warmer environments (low elevation or south facing sites) were poorly adapted to the north-facing garden. In high and low elevation Colorado gardens, susceptibility to insect herbivory increased with source elevation. In the high elevation Colorado garden, germination success peaked for genotypes that evolved at similar elevations as the garden, and declined for genotypes from higher and lower elevations. We also found evidence for local maladaptation in survival and fecundity components of fitness in the low elevation Colorado garden. This approach is a necessary first step in predicting how global change could affect evolutionary dynamics. PMID:26656218

Patterning of alloy precipitation through external pressure

NASA Astrophysics Data System (ADS)

Franklin, Jack A.

Due to the nature of their microstructure, alloyed components have the benefit of meeting specific design goals across a wide range of electrical, thermal, and mechanical properties. In general by selecting the correct alloy system and applying a proper heat treatment it is possible to create a metallic sample whose properties achieve a unique set of design requirements. This dissertation presents an innovative processing technique intended to control both the location of formation and the growth rates of precipitates within metallic alloys in order to create multiple patterned areas of unique microstructure within a single sample. Specific experimental results for the Al-Cu alloy system will be shown. The control over precipitation is achieved by altering the conventional heat treatment process with an external surface load applied to selected locations during the quench and anneal. It is shown that the applied pressures affect both the rate and directionality of the atomic diffusion in regions close to the loaded surfaces. The control over growth rates is achieved by altering the enthalpic energy required for successful diffusion between lattice sites. Changes in the local chemical free energy required to direct the diffusion of atoms are established by introducing a non-uniform elastic strain energy field within the samples created by the patterned surface pressures. Either diffusion rates or atomic mobility can be selected as the dominating control process by varying the quench rate; with slower quenches having greater control over the mobility of the alloying elements. Results have shown control of Al2Cu precipitation over 100 microns on mechanically polished surfaces. Further experimental considerations presented will address consistency across sample ensembles. This includes repeatable pressure loading conditions and the chemical interaction between any furnace environments and both the alloy sample and metallic pressure loading devices.

Health plan competition in local markets.

PubMed Central

Grossman, J M

2000-01-01

OBJECTIVE: To examine the structure of local health insurance markets and the strategies health plans were using to respond to competitive pressures in local markets in 1996/1997. DATA SOURCES/STUDY SETTING: Community Tracking Study site visits conducted between May 1996 and April 1997 in 12 U.S. markets selected to be nationally representative. STUDY DESIGN: In each site, 36 to 60 interviews on local health system change were conducted with healthcare industry informants representing health plans, providers, and purchasers. DATA COLLECTION/EXTRACTION METHOD: Relevant data for this article were abstracted from standardized protocols administered to multiple respondents in each site. PRINCIPAL FINDINGS: Although the competitive threat from national plans was pervasive, local plans in most sites continued to retain strong, often dominant, positions in historically concentrated markets. In all sites, in response to purchaser pressures for stable premiums and provider choice, and the threat of entry and to plans were using three strategies to increase market share and market power: (1) consolidation/geographic expansion, (2) price competition, and (3) product line/segment diversification that focused on broad networks and open-access products. In most markets, in response to the demand for provider choice, the trend was away from ownership and exclusive arrangements with providers. CONCLUSIONS: Although local plans were moving to become full-service regional players, there was uncertainty about the abilities of all plans to sustain growth strategies at the expense of margins and organizational stability, and to effectively manage care with broad networks. PMID:10778822

Genome-wide analysis of selection on the malaria parasite Plasmodium falciparum in West African populations of differing infection endemicity.

PubMed

Mobegi, Victor A; Duffy, Craig W; Amambua-Ngwa, Alfred; Loua, Kovana M; Laman, Eugene; Nwakanma, Davis C; MacInnis, Bronwyn; Aspeling-Jones, Harvey; Murray, Lee; Clark, Taane G; Kwiatkowski, Dominic P; Conway, David J

2014-06-01

Locally varying selection on pathogens may be due to differences in drug pressure, host immunity, transmission opportunities between hosts, or the intensity of between-genotype competition within hosts. Highly recombining populations of the human malaria parasite Plasmodium falciparum throughout West Africa are closely related, as gene flow is relatively unrestricted in this endemic region, but markedly varying ecology and transmission intensity should cause distinct local selective pressures. Genome-wide analysis of sequence variation was undertaken on a sample of 100 P. falciparum clinical isolates from a highly endemic region of the Republic of Guinea where transmission occurs for most of each year and compared with data from 52 clinical isolates from a previously sampled population from The Gambia, where there is relatively limited seasonal malaria transmission. Paired-end short-read sequences were mapped against the 3D7 P. falciparum reference genome sequence, and data on 136,144 single nucleotide polymorphisms (SNPs) were obtained. Within-population analyses identifying loci showing evidence of recent positive directional selection and balancing selection confirm that antimalarial drugs and host immunity have been major selective agents. Many of the signatures of recent directional selection reflected by standardized integrated haplotype scores were population specific, including differences at drug resistance loci due to historically different antimalarial use between the countries. In contrast, both populations showed a similar set of loci likely to be under balancing selection as indicated by very high Tajima's D values, including a significant overrepresentation of genes expressed at the merozoite stage that invades erythrocytes and several previously validated targets of acquired immunity. Between-population FST analysis identified exceptional differentiation of allele frequencies at a small number of loci, most markedly for five SNPs covering a 15-kb region within and flanking the gdv1 gene that regulates the early stages of gametocyte development, which is likely related to the extreme differences in mosquito vector abundance and seasonality that determine the transmission opportunities for the sexual stage of the parasite. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

NASA Astrophysics Data System (ADS)

Rajabifar, Bahram; Kim, Sanha; Slinker, Keith; Ehlert, Gregory J.; Hart, A. John; Maschmann, Matthew R.

2015-10-01

We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, and CNT orientation. Milled cuts with depths between 0-100 microns are generated, corresponding to a material removal rate of up to 20.1 μm3/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.

Three-dimensional machining of carbon nanotube forests using water-assisted scanning electron microscope processing

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

Rajabifar, Bahram; Maschmann, Matthew R., E-mail: MaschmannM@missouri.edu; Kim, Sanha

2015-10-05

We demonstrate that vertically aligned carbon nanotubes (CNTs) can be precisely machined in a low pressure water vapor ambient using the electron beam of an environmental scanning electron microscope. The electron beam locally damages the irradiated regions of the CNT forest and also dissociates the water vapor molecules into reactive species including hydroxyl radicals. These species then locally oxidize the damaged region of the CNTs. The technique offers material removal capabilities ranging from selected CNTs to hundreds of cubic microns. We study how the material removal rate is influenced by the acceleration voltage, beam current, dwell time, operating pressure, andmore » CNT orientation. Milled cuts with depths between 0–100 microns are generated, corresponding to a material removal rate of up to 20.1 μm{sup 3}/min. The technique produces little carbon residue and does not disturb the native morphology of the CNT network. Finally, we demonstrate direct machining of pyramidal surfaces and re-entrant cuts to create freestanding geometries.« less

Adaptive Role of Inversion Polymorphism of Drosophila subobscura in Lead Stressed Environment

PubMed Central

Kenig, Bojan; Kurbalija Novičić, Zorana; Patenković, Aleksandra; Stamenković-Radak, Marina; Anđelković, Marko

2015-01-01

Local adaptation to environmental stress at different levels of genetic polymorphism in various plants and animals has been documented through evolution of heavy metal tolerance. We used samples of Drosophila subobscura populations from two differently polluted environments to analyze the change of chromosomal inversion polymorphism as genetic marker during laboratory exposure to lead. Exposure to environmental contamination can affect the genetic content within a particular inversion and produce targets for selection in populations from different environments. The aims were to discover whether the inversion polymorphism is shaped by the local natural environments, and if lead as a selection pressure would cause adaptive divergence of two populations during the multigenerational laboratory experiment. The results showed that populations retain signatures from past contamination events, and that heavy metal pollution can cause adaptive changes in population. Differences in inversion polymorphism between the two populations increased over generations under lead contamination in the laboratory. The inversion polymorphism of population originating from the more polluted natural environment was more stable during the experiment, both under conditions with and without lead. Therefore, results showed that inversion polymorphism as a genetic marker reflects a strong signature of adaptation to the local environment, and that historical demographic events and selection are important for both prediction of evolutionary potential and long-term viability of natural populations. PMID:26102201

Adaptive Role of Inversion Polymorphism of Drosophila subobscura in Lead Stressed Environment.

PubMed

Kenig, Bojan; Kurbalija Novičić, Zorana; Patenković, Aleksandra; Stamenković-Radak, Marina; Anđelković, Marko

2015-01-01

Local adaptation to environmental stress at different levels of genetic polymorphism in various plants and animals has been documented through evolution of heavy metal tolerance. We used samples of Drosophila subobscura populations from two differently polluted environments to analyze the change of chromosomal inversion polymorphism as genetic marker during laboratory exposure to lead. Exposure to environmental contamination can affect the genetic content within a particular inversion and produce targets for selection in populations from different environments. The aims were to discover whether the inversion polymorphism is shaped by the local natural environments, and if lead as a selection pressure would cause adaptive divergence of two populations during the multigenerational laboratory experiment. The results showed that populations retain signatures from past contamination events, and that heavy metal pollution can cause adaptive changes in population. Differences in inversion polymorphism between the two populations increased over generations under lead contamination in the laboratory. The inversion polymorphism of population originating from the more polluted natural environment was more stable during the experiment, both under conditions with and without lead. Therefore, results showed that inversion polymorphism as a genetic marker reflects a strong signature of adaptation to the local environment, and that historical demographic events and selection are important for both prediction of evolutionary potential and long-term viability of natural populations.

Regulation of coronary blood flow

PubMed Central

Gorlin, Richard

1971-01-01

Coronary blood flow is dependent upon arterial pressure, diastolic time, and small vessel resistance. The system is regulated to achieve a low flow high oxygen extraction and low myocardial Po2. This setting is sensitive to change in oxygen needs. Regulation of blood flow occurs primarily through local intrinsic regulation, most likely through production of vasodilating metabolites in response to minimal degrees of ischaemia. Local regulation appears to dominate over remote regulation in most circumstances. Blood flow distribution to the myocardium is depth dependent as well as regional in variation. Both types of distribution of blood flow are profoundly disturbed in the presence of obstructive coronary atherosclerosis. This results in either concentric myocardial shells or patchy transmural zones of selective ischaemia with clear-cut but local abnormalities in metabolism and performance. Images PMID:4929442

Tailoring force sensitivity and selectivity by microstructure engineering of multidirectional electronic skins

NASA Astrophysics Data System (ADS)

Park, Jonghwa; Kim, Jinyoung; Hong, Jaehyung; Lee, Hochan; Lee, Youngoh; Cho, Seungse; Kim, Sung-Woo; Kim, Jae Joon; Kim, Sung Youb; Ko, Hyunhyub

2018-04-01

Electronic skins (e-skins) with high sensitivity to multidirectional mechanical stimuli are crucial for healthcare monitoring devices, robotics, and wearable sensors. In this study, we present piezoresistive e-skins with tunable force sensitivity and selectivity to multidirectional forces through the engineered microstructure geometries (i.e., dome, pyramid, and pillar). Depending on the microstructure geometry, distinct variations in contact area and localized stress distribution are observed under different mechanical forces (i.e., normal, shear, stretching, and bending), which critically affect the force sensitivity, selectivity, response/relaxation time, and mechanical stability of e-skins. Microdome structures present the best force sensitivities for normal, tensile, and bending stresses. In particular, microdome structures exhibit extremely high pressure sensitivities over broad pressure ranges (47,062 kPa-1 in the range of <1 kPa, 90,657 kPa-1 in the range of 1-10 kPa, and 30,214 kPa-1 in the range of 10-26 kPa). On the other hand, for shear stress, micropillar structures exhibit the highest sensitivity. As proof-of-concept applications in healthcare monitoring devices, we show that our e-skins can precisely monitor acoustic waves, breathing, and human artery/carotid pulse pressures. Unveiling the relationship between the microstructure geometry of e-skins and their sensing capability would provide a platform for future development of high-performance microstructured e-skins.

Sound localization in the alligator.

PubMed

Bierman, Hilary S; Carr, Catherine E

2015-11-01

In early tetrapods, it is assumed that the tympana were acoustically coupled through the pharynx and therefore inherently directional, acting as pressure difference receivers. The later closure of the middle ear cavity in turtles, archosaurs, and mammals is a derived condition, and would have changed the ear by decoupling the tympana. Isolation of the middle ears would then have led to selection for structural and neural strategies to compute sound source localization in both archosaurs and mammalian ancestors. In the archosaurs (birds and crocodilians) the presence of air spaces in the skull provided connections between the ears that have been exploited to improve directional hearing, while neural circuits mediating sound localization are well developed. In this review, we will focus primarily on directional hearing in crocodilians, where vocalization and sound localization are thought to be ecologically important, and indicate important issues still awaiting resolution. Copyright © 2015 Elsevier B.V. All rights reserved.

Evidence that the human cutaneous venoarteriolar response is not mediated by adrenergic mechanisms

NASA Technical Reports Server (NTRS)

Crandall, C. G.; Shibasaki, M.; Yen, T. C.

2002-01-01

The venoarteriolar response causes vasoconstriction to skin and muscle via local mechanisms secondary to venous congestion. The purpose of this project was to investigate whether this response occurs through alpha-adrenergic mechanisms. In supine individuals, forearm skin blood flow was monitored via laser-Doppler flowmetry over sites following local administration of terazosin (alpha(1)-antagonist), yohimbine (alpha(2)-antagonist), phentolamine (non-selective alpha-antagonist) and bretylium tosylate (inhibits neurotransmission of adrenergic nerves) via intradermal microdialysis or intradermal injection. In addition, skin blood flow was monitored over an area of forearm skin that was locally anaesthetized via application of EMLA (2.5 % lidocaine (lignocaine) and 2.5 % prilocaine) cream. Skin blood flow was also monitored over adjacent sites that received the vehicle for the specified drug. Each trial was performed on a minimum of seven subjects and on separate days. The venoarteriolar response was engaged by lowering the subject's arm from heart level such that the sites of skin blood flow measurement were 34 +/- 1 cm below the heart. The arm remained in this position for 2 min. Selective and non-selective alpha-adrenoceptor antagonism and presynaptic inhibition of adrenergic neurotransmission did not abolish the venoarteriolar response. However, local anaesthesia blocked the venoarteriolar response without altering alpha-adrenergic mediated vasoconstriction. These data suggest that the venoarteriolar response does not occur through adrenergic mechanisms as previously reported. Rather, the venoarteriolar response may due to myogenic mechanisms associated with changes in vascular pressure or is mediated by a non-adrenergic, but neurally mediated, local mechanism.

Demographic History, Population Structure, and Local Adaptation in Alpine Populations of Cardamine impatiens and Cardamine resedifolia

PubMed Central

Ometto, Lino; Li, Mingai; Bresadola, Luisa; Barbaro, Enrico; Neteler, Markus; Varotto, Claudio

2015-01-01

Species evolution depends on numerous and distinct forces, including demography and natural selection. For example, local adaptation and population structure affect the evolutionary history of species living along environmental clines. This is particularly relevant in plants, which are often characterized by limited dispersal ability and the need to respond to abiotic and biotic stress factors specific to the local environment. Here we study the demographic history and the possible existence of local adaptation in two related species of Brassicaceae, Cardamine impatiens and Cardamine resedifolia, which occupy separate habitats along the elevation gradient. Previous genome-wide analyses revealed the occurrence of distinct selective pressures in the two species, with genes involved in cold response evolving particularly fast in C. resedifolia. In this study we surveyed patterns of molecular evolution and genetic variability in a set of 19 genes, including neutral and candidate genes involved in cold response, across 10 populations each of C. resedifolia and C. impatiens from the Italian Alps (Trentino). We inferred the population structure and demographic history of the two species, and tested the occurrence of signatures of local adaptation in these genes. The results indicate that, despite a slightly higher population differentiation in C. resedifolia than in C. impatiens, both species are only weakly structured and that populations sampled at high altitude experience less gene flow than low-altitude ones. None of the genes showed signatures of positive selection, suggesting that they do not seem to play relevant roles in the current evolutionary processes of adaptation to alpine environments of these species. PMID:25933225

Short review of high-pressure crystal growth and magnetic and electrical properties of solid-state osmium oxides

NASA Astrophysics Data System (ADS)

Yamaura, Kazunari

2016-04-01

High-pressure crystal growth and synthesis of selected solid-state osmium oxides, many of which are perovskite-related types, are briefly reviewed, and their magnetic and electrical properties are introduced. Crystals of the osmium oxides, including NaOsO3, LiOsO3, and Na2OsO4, were successfully grown under high-pressure and high-temperature conditions at 6 GPa in the presence of an appropriate amount of flux in a belt-type apparatus. The unexpected discovery of a magnetic metal-insulator transition in NaOsO3, a ferroelectric-like transition in LiOsO3, and high-temperature ferrimagnetism driven by a local structural distortion in Ca2FeOsO6 may represent unique features of the osmium oxides. The high-pressure and high-temperature synthesis and crystal growth has played a central role in the development of solid-state osmium oxides and the elucidation of their magnetic and electronic properties toward possible use in multifunctional devices.

Prediction of Burst Pressure in Multistage Tube Hydroforming of Aerospace Alloys.

PubMed

Saboori, M; Gholipour, J; Champliaud, H; Wanjara, P; Gakwaya, A; Savoie, J

2016-08-01

Bursting, an irreversible failure in tube hydroforming (THF), results mainly from the local plastic instabilities that occur when the biaxial stresses imparted during the process exceed the forming limit strains of the material. To predict the burst pressure, Oyan's and Brozzo's decoupled ductile fracture criteria (DFC) were implemented as user material models in a dynamic nonlinear commercial 3D finite-element (FE) software, ls-dyna. THF of a round to V-shape was selected as a generic representative of an aerospace component for the FE simulations and experimental trials. To validate the simulation results, THF experiments up to bursting were carried out using Inconel 718 (IN 718) tubes with a thickness of 0.9 mm to measure the internal pressures during the process. When comparing the experimental and simulation results, the burst pressure predicated based on Oyane's decoupled damage criterion was found to agree better with the measured data for IN 718 than Brozzo's fracture criterion.

Local probing of ferroelectric and ferroelastic switching through stress-mediated piezoelectric spectroscopy

DOE PAGES

Edwards, David; Bastani, Yaser; Cao, Ye; ...

2016-01-19

The role of local strains is fundamental to the large effective piezoelectric and ferroelectric response of thin films. Therefore a method to investigate local strain-induced phenomena is imperative. Here, pressure induced domain reorganization is reported in lead zirconate titanate films with composition near the morphotropic phase boundary. An approach is thus demonstrated to simultaneously study the role of applied mechanical pressure on multiple local properties of the film. In particular, the modification of hysteresis loops collected at different tip pressures is consistent with first mostly ferroelastic and then ferroelectric dominated reorientation of domains under increasing applied pressure. The pressure inducedmore » domain writing is also investigated through phase field simulations where the applied pressure is generally found to increase the in-plane polarization of the domains with respect to the out-of-plane component, corroborating the experimental observations. The approach developed here has the potential to explore other hysteretic phenomena and phase transitions in a spatially resolved manner with varying local pressure.« less

Genetic heterogeneity underlying variation in a locally adaptive clinal trait in Pinus sylvestris revealed by a Bayesian multipopulation analysis.

PubMed

Kujala, S T; Knürr, T; Kärkkäinen, K; Neale, D B; Sillanpää, M J; Savolainen, O

2017-05-01

Local adaptation is a common feature of plant and animal populations. Adaptive phenotypic traits are genetically differentiated along environmental gradients, but the genetic basis of such adaptation is still poorly known. Genetic association studies of local adaptation combine data over populations. Correcting for population structure in these studies can be problematic since both selection and neutral demographic events can create similar allele frequency differences between populations. Correcting for demography with traditional methods may lead to eliminating some true associations. We developed a new Bayesian approach for identifying the loci underlying an adaptive trait in a multipopulation situation in the presence of possible double confounding due to population stratification and adaptation. With this method we studied the genetic basis of timing of bud set, a surrogate trait for timing of yearly growth cessation that confers local adaptation to the populations of Scots pine (Pinus sylvestris). Population means of timing of bud set were highly correlated with latitude. Most effects at individual loci were small. Interestingly, we found genetic heterogeneity (that is, different sets of loci associated with the trait) between the northern and central European parts of the cline. We also found indications of stronger stabilizing selection toward the northern part of the range. The harsh northern conditions may impose greater selective pressure on timing of growth cessation, and the relative importance of different environmental cues used for tracking the seasons might differ depending on latitude of origin.

Ammonia Synthesis at Low Pressure.

PubMed

Cussler, Edward; McCormick, Alon; Reese, Michael; Malmali, Mahdi

2017-08-23

Ammonia can be synthesized at low pressure by the use of an ammonia selective absorbent. The process can be driven with wind energy, available locally in areas requiring ammonia for synthetic fertilizer. Such wind energy is often called "stranded," because it is only available far from population centers where it can be directly used. In the proposed low pressure process, nitrogen is made from air using pressure swing absorption, and hydrogen is produced by electrolysis of water. While these gases can react at approximately 400 °C in the presence of a promoted conventional catalyst, the conversion is often limited by the reverse reaction, which makes this reaction only feasible at high pressures. This limitation can be removed by absorption on an ammine-like calcium or magnesium chloride. Such alkaline metal halides can effectively remove ammonia, thus suppressing the equilibrium constraints of the reaction. In the proposed absorption-enhanced ammonia synthesis process, the rate of reaction may then be controlled not by the chemical kinetics nor the absorption rates, but by the rate of the recycle of unreacted gases. The results compare favorably with ammonia made from a conventional small scale Haber-Bosch process.

Sensitivity, stability, and precision of quantitative Ns-LIBS-based fuel-air-ratio measurements for methane-air flames at 1-11 bar.

PubMed

Hsu, Paul S; Gragston, Mark; Wu, Yue; Zhang, Zhili; Patnaik, Anil K; Kiefer, Johannes; Roy, Sukesh; Gord, James R

2016-10-01

Nanosecond laser-induced breakdown spectroscopy (ns-LIBS) is employed for quantitative local fuel-air (F/A) ratio (i.e., ratio of actual fuel-to-oxidizer mass over ratio of fuel-to-oxidizer mass at stoichiometry, measurements in well-characterized methane-air flames at pressures of 1-11 bar). We selected nitrogen and hydrogen atomic-emission lines at 568 nm and 656 nm, respectively, to establish a correlation between the line intensities and the F/A ratio. We have investigated the effects of laser-pulse energy, camera gate delay, and pressure on the sensitivity, stability, and precision of the quantitative ns-LIBS F/A ratio measurements. We determined the optimal laser energy and camera gate delay for each pressure condition and found that measurement stability and precision are degraded with an increase in pressure. We have identified primary limitations of the F/A ratio measurement employing ns-LIBS at elevated pressures as instabilities caused by the higher density laser-induced plasma and the presence of the higher level of soot. Potential improvements are suggested.

Genetic structure and signatures of selection in grey reef sharks (Carcharhinus amblyrhynchos).

PubMed

Momigliano, P; Harcourt, R; Robbins, W D; Jaiteh, V; Mahardika, G N; Sembiring, A; Stow, A

2017-09-01

With overfishing reducing the abundance of marine predators in multiple marine ecosystems, knowledge of genetic structure and local adaptation may provide valuable information to assist sustainable management. Despite recent technological advances, most studies on sharks have used small sets of neutral markers to describe their genetic structure. We used 5517 nuclear single-nucleotide polymorphisms (SNPs) and a mitochondrial DNA (mtDNA) gene to characterize patterns of genetic structure and detect signatures of selection in grey reef sharks (Carcharhinus amblyrhynchos). Using samples from Australia, Indonesia and oceanic reefs in the Indian Ocean, we established that large oceanic distances represent barriers to gene flow, whereas genetic differentiation on continental shelves follows an isolation by distance model. In Australia and Indonesia differentiation at nuclear SNPs was weak, with coral reefs acting as stepping stones maintaining connectivity across large distances. Differentiation of mtDNA was stronger, and more pronounced in females, suggesting sex-biased dispersal. Four independent tests identified a set of loci putatively under selection, indicating that grey reef sharks in eastern Australia are likely under different selective pressures to those in western Australia and Indonesia. Genetic distances averaged across all loci were uncorrelated with genetic distances calculated from outlier loci, supporting the conclusion that different processes underpin genetic divergence in these two data sets. This pattern of heterogeneous genomic differentiation, suggestive of local adaptation, has implications for the conservation of grey reef sharks; furthermore, it highlights that marine species showing little genetic differentiation at neutral loci may exhibit patterns of cryptic genetic structure driven by local selection.

Low pressure CO₂ hydrogenation to methanol over gold nanoparticles activated on a CeO x/TiO₂ interface

DOE PAGES

Yang, Xiaofang; Boscoboinik, J. Anibal; Kattel, Shyam; ...

2015-07-28

Capture and recycling of CO 2 into valuable chemicals such as alcohols could help mitigate its emissions into the atmosphere. Due to its inert nature, the activation of CO 2 is a critical step in improving the overall reaction kinetics during its chemical conversion. Although pure gold is an inert noble metal and cannot catalyze hydrogenation reactions, it can be activated when deposited as nanoparticles on the appropriate oxide support. In this combined experimental and theoretical study, it is shown that an electronic polarization at the metal-oxide interface of Au nanoparticles anchored and stabilized on a CeO x/TiO 2 substratemore » generates active centers for CO 2 adsorption and its low pressure hydrogenation, leading to a higher selectivity towards methanol. As a result, this study illustrates the importance of localized electronic properties and structure in catalysis for achieving higher alcohol selectivity from CO 2 hydrogenation.« less

Non-Random Inversion Landscapes in Prokaryotic Genomes Are Shaped by Heterogeneous Selection Pressures

PubMed Central

Repar, Jelena; Warnecke, Tobias

2017-01-01

Abstract Inversions are a major contributor to structural genome evolution in prokaryotes. Here, using a novel alignment-based method, we systematically compare 1,651 bacterial and 98 archaeal genomes to show that inversion landscapes are frequently biased toward (symmetric) inversions around the origin–terminus axis. However, symmetric inversion bias is not a universal feature of prokaryotic genome evolution but varies considerably across clades. At the extremes, inversion landscapes in Bacillus–Clostridium and Actinobacteria are dominated by symmetric inversions, while there is little or no systematic bias favoring symmetric rearrangements in archaea with a single origin of replication. Within clades, we find strong but clade-specific relationships between symmetric inversion bias and different features of adaptive genome architecture, including the distance of essential genes to the origin of replication and the preferential localization of genes on the leading strand. We suggest that heterogeneous selection pressures have converged to produce similar patterns of structural genome evolution across prokaryotes. PMID:28407093

Adaptations to Climate-Mediated Selective Pressures in Sheep

PubMed Central

Lv, Feng-Hua; Agha, Saif; Kantanen, Juha; Colli, Licia; Stucki, Sylvie; Kijas, James W.; Joost, Stéphane; Li, Meng-Hua; Ajmone Marsan, Paolo

2014-01-01

Following domestication, sheep (Ovis aries) have become essential farmed animals across the world through adaptation to a diverse range of environments and varied production systems. Climate-mediated selective pressure has shaped phenotypic variation and has left genetic “footprints” in the genome of breeds raised in different agroecological zones. Unlike numerous studies that have searched for evidence of selection using only population genetics data, here, we conducted an integrated coanalysis of environmental data with single nucleotide polymorphism (SNP) variation. By examining 49,034 SNPs from 32 old, autochthonous sheep breeds that are adapted to a spectrum of different regional climates, we identified 230 SNPs with evidence for selection that is likely due to climate-mediated pressure. Among them, 189 (82%) showed significant correlation (P ≤ 0.05) between allele frequency and climatic variables in a larger set of native populations from a worldwide range of geographic areas and climates. Gene ontology analysis of genes colocated with significant SNPs identified 17 candidates related to GTPase regulator and peptide receptor activities in the biological processes of energy metabolism and endocrine and autoimmune regulation. We also observed high linkage disequilibrium and significant extended haplotype homozygosity for the core haplotype TBC1D12-CH1 of TBC1D12. The global frequency distribution of the core haplotype and allele OAR22_18929579-A showed an apparent geographic pattern and significant (P ≤ 0.05) correlations with climatic variation. Our results imply that adaptations to local climates have shaped the spatial distribution of some variants that are candidates to underpin adaptive variation in sheep. PMID:25249477

Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landraces and cultivars.

PubMed

Cavanagh, Colin R; Chao, Shiaoman; Wang, Shichen; Huang, Bevan Emma; Stephen, Stuart; Kiani, Seifollah; Forrest, Kerrie; Saintenac, Cyrille; Brown-Guedira, Gina L; Akhunova, Alina; See, Deven; Bai, Guihua; Pumphrey, Michael; Tomar, Luxmi; Wong, Debbie; Kong, Stephan; Reynolds, Matthew; da Silva, Marta Lopez; Bockelman, Harold; Talbert, Luther; Anderson, James A; Dreisigacker, Susanne; Baenziger, Stephen; Carter, Arron; Korzun, Viktor; Morrell, Peter Laurent; Dubcovsky, Jorge; Morell, Matthew K; Sorrells, Mark E; Hayden, Matthew J; Akhunov, Eduard

2013-05-14

Domesticated crops experience strong human-mediated selection aimed at developing high-yielding varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated single-nucleotide polymorphisms (SNP) in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. Using a SNP-based diversity map we characterized the impact of crop improvement on genomic and geographic patterns of genetic diversity. We found evidence of a small population bottleneck and extensive use of ancestral variation often traceable to founders of cultivars from diverse geographic regions. Analyzing genetic differentiation among populations and the extent of haplotype sharing, we identified allelic variants subjected to selection during improvement. Selective sweeps were found around genes involved in the regulation of flowering time and phenology. An introgression of a wild relative-derived gene conferring resistance to a fungal pathogen was detected by haplotype-based analysis. Comparing selective sweeps identified in different populations, we show that selection likely acts on distinct targets or multiple functionally equivalent alleles in different portions of the geographic range of wheat. The majority of the selected alleles were present at low frequency in local populations, suggesting either weak selection pressure or temporal variation in the targets of directional selection during breeding probably associated with changing agricultural practices or environmental conditions. The developed SNP chip and map of genetic variation provide a resource for advancing wheat breeding and supporting future population genomic and genome-wide association studies in wheat.

Genome-wide comparative diversity uncovers multiple targets of selection for improvement in hexaploid wheat landraces and cultivars

PubMed Central

Cavanagh, Colin R.; Chao, Shiaoman; Wang, Shichen; Huang, Bevan Emma; Stephen, Stuart; Kiani, Seifollah; Forrest, Kerrie; Saintenac, Cyrille; Brown-Guedira, Gina L.; Akhunova, Alina; See, Deven; Bai, Guihua; Pumphrey, Michael; Tomar, Luxmi; Wong, Debbie; Kong, Stephan; Reynolds, Matthew; da Silva, Marta Lopez; Bockelman, Harold; Talbert, Luther; Anderson, James A.; Dreisigacker, Susanne; Baenziger, Stephen; Carter, Arron; Korzun, Viktor; Morrell, Peter Laurent; Dubcovsky, Jorge; Morell, Matthew K.; Sorrells, Mark E.; Hayden, Matthew J.; Akhunov, Eduard

2013-01-01

Domesticated crops experience strong human-mediated selection aimed at developing high-yielding varieties adapted to local conditions. To detect regions of the wheat genome subject to selection during improvement, we developed a high-throughput array to interrogate 9,000 gene-associated single-nucleotide polymorphisms (SNP) in a worldwide sample of 2,994 accessions of hexaploid wheat including landraces and modern cultivars. Using a SNP-based diversity map we characterized the impact of crop improvement on genomic and geographic patterns of genetic diversity. We found evidence of a small population bottleneck and extensive use of ancestral variation often traceable to founders of cultivars from diverse geographic regions. Analyzing genetic differentiation among populations and the extent of haplotype sharing, we identified allelic variants subjected to selection during improvement. Selective sweeps were found around genes involved in the regulation of flowering time and phenology. An introgression of a wild relative-derived gene conferring resistance to a fungal pathogen was detected by haplotype-based analysis. Comparing selective sweeps identified in different populations, we show that selection likely acts on distinct targets or multiple functionally equivalent alleles in different portions of the geographic range of wheat. The majority of the selected alleles were present at low frequency in local populations, suggesting either weak selection pressure or temporal variation in the targets of directional selection during breeding probably associated with changing agricultural practices or environmental conditions. The developed SNP chip and map of genetic variation provide a resource for advancing wheat breeding and supporting future population genomic and genome-wide association studies in wheat. PMID:23630259

Selective sweeps in the homoploid hybrid species Helianthus deserticola: evolution in concert across populations and across origins

PubMed Central

GROSS, BRIANA L.; TURNER, KATHRYN G.; RIESEBERG, LOREN H.

2008-01-01

The evolution of different populations within a species in response to selective pressures can potentially happen in three different ways. It can occur in parallel, where similar changes occur independently in each population in response to selection; in concert, where the spread of an adaptive mutation across a species’ range results in a single allele fixing in each population; or populations can diverge in response to local selective pressures. We explored these possibilities in populations of the homoploid hybrid species Helianthus deserticola relative to its parental species Helianthus annuus and Helianthus petiolaris using an analysis of variation in 96 expressed sequence tag-based microsatellites. A total of nine loci showed evidence consistent with recent selection at either the species or population level, although two of these genes were discarded because the apparent sweep did not occur relative to the parent from which the locus was derived. Between one and five loci showed a putative sweep across the entire species range with the same microsatellite allele fixed in each population. This pattern is consistent with evolution in concert despite geographical isolation and potential independent origins of the populations. Only one population of H. deserticola showed candidate sweeps that were unique compared to the rest of the species, and this population has also potentially experienced recent admixture with the parental species. PMID:18092993

Predation drives interpopulation differences in parental care expression.

PubMed

Huang, Wen-San; Lin, Si-Min; Dubey, Sylvain; Pike, David A

2013-03-01

Expressing parental care after oviposition or parturition is usually an obligate (evolved) trait within a species, despite evolutionary theory predicting that widespread species should vary in whether or not they express parental care according to local selection pressures. The lizard Eutropis longicaudata expresses maternal care only in a single population throughout its large geographical range, but why this pattern occurs is unknown. We used reciprocal translocation and predator exclusion experiments to test whether this intraspecific variation is a fixed trait within populations and whether predator abundance explains this perplexing pattern. Wild-caught female lizards that were reciprocally translocated consistently guarded or abandoned eggs in line with their population of origin. By contrast, most lizards raised in a common garden environment and subsequently released as adults adopted the maternal care strategy of the recipient population, even when the parents originated from a population lacking maternal care. Egg predation represents a significant fitness cost in the populations where females display egg-guarding behaviour, but guarding eggs outweighs this potential cost by increasing hatching success. These results imply that predators can be a driving force in the expression of parental care in instances where it is normally absent and that local selection pressure is sufficient to cause behavioural divergence in whether or not parental care is expressed. © 2012 The Authors. Journal of Animal Ecology © 2012 British Ecological Society.

Analytical solution for shear bands in cold-rolled 1018 steel

NASA Astrophysics Data System (ADS)

Voyiadjis, George Z.; Almasri, Amin H.; Faghihi, Danial; Palazotto, Anthony N.

2012-06-01

Cold-rolled 1018 (CR-1018) carbon steel has been well known for its susceptibility to adiabatic shear banding under dynamic loadings. Analysis of these localizations highly depends on the selection of the constitutive model. To deal with this issue, a constitutive model that takes temperature and strain rate effect into account is proposed. The model is motivated by two physical-based models: the Zerilli and Armstrong and the Voyiadjis and Abed models. This material model, however, incorporates a simple softening term that is capable of simulating the softening behavior of CR-1018 steel. Instability, localization, and evolution of adiabatic shear bands are discussed and presented graphically. In addition, the effect of hydrostatic pressure is illustrated.

Adverse Outcomes after Major Surgery in Patients with Pressure Ulcer: A Nationwide Population-Based Retrospective Cohort Study

PubMed Central

Chou, Chia-Lun; Lee, Woan-Ruoh; Yeh, Chun-Chieh; Shih, Chun-Chuan

2015-01-01

Background Postoperative adverse outcomes in patients with pressure ulcer are not completely understood. This study evaluated the association between preoperative pressure ulcer and adverse events after major surgeries. Methods Using reimbursement claims from Taiwan’s National Health Insurance Research Database, we conducted a nationwide retrospective cohort study of 17391 patients with preoperative pressure ulcer receiving major surgery in 2008-2010. With a propensity score matching procedure, 17391 surgical patients without pressure ulcer were selected for comparison. Eight major surgical postoperative complications and 30-day postoperative mortality were evaluated among patients with pressure ulcer of varying severity. Results Patients with preoperative pressure ulcer had significantly higher risk than controls for postoperative adverse outcomes, including septicemia, pneumonia, stroke, urinary tract infection, and acute renal failure. Surgical patients with pressure ulcer had approximately 1.83-fold risk (95% confidence interval 1.54-2.18) of 30-day postoperative mortality compared with control group. The most significant postoperative mortality was found in those with serious pressure ulcer, such as pressure ulcer with local infection, cellulitis, wound or treatment by change dressing, hospitalized care, debridement or antibiotics. Prolonged hospital or intensive care unit stay and increased medical expenditures were also associated with preoperative pressure ulcer. Conclusion This nationwide propensity score-matched retrospective cohort study showed increased postoperative complications and mortality in patients with preoperative pressure ulcer. Our findings suggest the urgency of preventing and managing preoperative pressure ulcer by a multidisciplinary medical team for this specific population. PMID:26000606

Prediction of pharmacologically induced baroreflex sensitivity from local time and frequency domain indices of R-R interval and systolic blood pressure signals obtained during deep breathing.

PubMed

Arica, Sami; Firat Ince, N; Bozkurt, Abdi; Tewfik, Ahmed H; Birand, Ahmet

2011-07-01

Pharmacological measurement of baroreflex sensitivity (BRS) is widely accepted and used in clinical practice. Following the introduction of pharmacologically induced BRS (p-BRS), alternative assessment methods eliminating the use of drugs were in the center of interest of the cardiovascular research community. In this study we investigated whether p-BRS using phenylephrine injection can be predicted from non-pharmacological time and frequency domain indices computed from electrocardiogram (ECG) and blood pressure (BP) data acquired during deep breathing. In this scheme, ECG and BP data were recorded from 16 subjects in a two-phase experiment. In the first phase the subjects performed irregular deep breaths and in the second phase the subjects received phenylephrine injection. From the first phase of the experiment, a large pool of predictors describing the local characteristic of beat-to-beat interval tachogram (RR) and systolic blood pressure (SBP) were extracted in time and frequency domains. A subset of these indices was selected using twelve subjects with an exhaustive search fused with a leave one subject out cross validation procedure. The selected indices were used to predict the p-BRS on the remaining four test subjects. A multivariate regression was used in all prediction steps. The algorithm achieved best prediction accuracy with only two features extracted from the deep breathing data, one from the frequency and the other from the time domain. The normalized L2-norm error was computed as 22.9% and the correlation coefficient was 0.97 (p=0.03). These results suggest that the p-BRS can be estimated from non-pharmacological indices computed from ECG and invasive BP data related to deep breathing. Copyright © 2011 Elsevier Ltd. All rights reserved.

Radiative interactions in molecular gases under local and nonlocal thermodynamic equilibrium conditions

NASA Technical Reports Server (NTRS)

Tiwari, S. N.; Jha, M. K.

1993-01-01

Basic formulations, analyses, and numerical procedures are presented to investigate radiative heat interactions in diatomic and polyatomic gases under local and nonlocal thermodynamic equilibrium conditions. Essential governing equations are presented for both gray and nongray gases. Information is provided on absorption models, relaxation times, and transfer equations. Radiative flux equations are developed which are applicable under local and nonlocal thermodynamic equilibrium conditions. The problem is solved for fully developed laminar incompressible flows between two parallel plates under the boundary condition of a uniform surface heat flux. For specific applications, three diatomic and three polyatomic gases are considered. The results are obtained numerically by employing the method of variation of parameters. The results are compared under local and nonlocal thermodynamic equilibrium conditions at different temperature and pressure conditions. Both gray and nongray studies are conducted extensively for all molecular gases considered. The particular gases selected for this investigation are CO, NO, OH, CO2, H2O, and CH4. The temperature and pressure range considered are 300-2000 K and 0.1-10 atmosphere, respectively. In general, results demonstrate that the gray gas approximation overestimates the effect of radiative interaction for all conditions. The conditions of NLTE, however, result in underestimation of radiative interactions. The method developed for this study can be extended to solve complex problems of radiative heat transfer involving nonequilibrium phenomena.

Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains’ precipitation gradient: implications for grassland restoration with climate change

PubMed Central

Johnson, Loretta C; Olsen, Jacob T; Tetreault, Hannah; DeLaCruz, Angel; Bryant, Johnny; Morgan, Theodore J; Knapp, Mary; Bello, Nora M; Baer, Sara G; Maricle, Brian R

2015-01-01

Identifying suitable genetic stock for restoration often employs a ‘best guess’ approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations. PMID:26240607

Intraspecific variation of a dominant grass and local adaptation in reciprocal garden communities along a US Great Plains' precipitation gradient: implications for grassland restoration with climate change.

PubMed

Johnson, Loretta C; Olsen, Jacob T; Tetreault, Hannah; DeLaCruz, Angel; Bryant, Johnny; Morgan, Theodore J; Knapp, Mary; Bello, Nora M; Baer, Sara G; Maricle, Brian R

2015-08-01

Identifying suitable genetic stock for restoration often employs a 'best guess' approach. Without adaptive variation studies, restoration may be misguided. We test the extent to which climate in central US grasslands exerts selection pressure on a foundation grass big bluestem (Andropogon gerardii), widely used in restorations, and resulting in local adaptation. We seeded three regional ecotypes of A. gerardii in reciprocal transplant garden communities across 1150 km precipitation gradient. We measured ecological responses over several timescales (instantaneous gas exchange, medium-term chlorophyll absorbance, and long-term responses of establishment and cover) in response to climate and biotic factors and tested if ecotypes could expand range. The ecotype from the driest region exhibited greatest cover under low rainfall, suggesting local adaptation under abiotic stress. Unexpectedly, no evidence for cover differences between ecotypes exists at mesic sites where establishment and cover of all ecotypes were low, perhaps due to strong biotic pressures. Expression of adaptive differences is strongly environment specific. Given observed adaptive variation, the most conservative restoration strategy would be to plant the local ecotype, especially in drier locations. With superior performance of the most xeric ecotype under dry conditions and predicted drought, this ecotype may migrate eastward, naturally or with assistance in restorations.

Direct Laser Writing of Porous-Carbon/Silver Nanocomposite for Flexible Electronics.

PubMed

Rahimi, Rahim; Ochoa, Manuel; Ziaie, Babak

2016-07-06

In this Research Article, we demonstrate a facile method for the fabrication of porous-carbon/silver nanocomposites using direct laser writing on polymeric substrates. Our technique uses a combination of CO2 laser-induced carbonization and selective silver deposition on a polyimide sheet to create flexible highly conductive traces. The localized laser irradiation selectively converts the polyimide to a highly porous and conductive carbonized film with superhydrophilic wettability. The resulting pattern allows for selective trapping of aqueous silver ionic ink solutions into the carbonized regions, which are converted to silver nanoparticle fillers upon an annealing step. Elemental and surface morphology analysis via XRD and SEM reveals a uniform coating of Ag nanoparticles on the porous carbon. The Ag/C composite lowers the sheet resistance of the original laser carbonized polyimide from 50 to 0.02 Ω/□. The resulting patterns are flexible and electromechanically robust with less than 0.6 Ω variation in resistance after >15000 bending flexion cycles at a radius of curvature of 5 mm. Furthermore, using this technique, we demonstrate the fabrication of a wireless resonant pressure sensor capable of detecting pressures ranging from 0 to 97 kPa with an average sensitivity of -26 kHz/kPa.

Blood pressure regulation V: in vivo mechanical properties of precapillary vessels as affected by long-term pressure loading and unloading.

PubMed

Eiken, Ola; Mekjavic, Igor B; Kölegård, Roger

2014-03-01

Recent studies are reviewed, concerning the in vivo wall stiffness of arteries and arterioles in healthy humans, and how these properties adapt to iterative increments or sustained reductions in local intravascular pressure. A novel technique was used, by which arterial and arteriolar stiffness was determined as changes in arterial diameter and flow, respectively, during graded increments in distending pressure in the blood vessels of an arm or a leg. Pressure-induced increases in diameter and flow were smaller in the lower leg than in the arm, indicating greater stiffness in the arteries/arterioles of the leg. A 5-week period of intermittent intravascular pressure elevations in one arm reduced pressure distension and pressure-induced flow in the brachial artery by about 50%. Conversely, prolonged reduction of arterial/arteriolar pressure in the lower body by 5 weeks of sustained horizontal bedrest, induced threefold increases of the pressure-distension and pressure-flow responses in a tibial artery. Thus, the wall stiffness of arteries and arterioles are plastic properties that readily adapt to changes in the prevailing local intravascular pressure. The discussion concerns mechanisms underlying changes in local arterial/arteriolar stiffness as well as whether stiffness is altered by changes in myogenic tone and/or wall structure. As regards implications, regulation of local arterial/arteriolar stiffness may facilitate control of arterial pressure in erect posture and conditions of exaggerated intravascular pressure gradients. That increased intravascular pressure leads to increased arteriolar wall stiffness also supports the notion that local pressure loading may constitute a prime mover in the development of vascular changes in hypertension.

Selective deletion of Connexin 40 in renin-producing cells impairs renal baroreceptor function and is associated with arterial hypertension

PubMed Central

Wagner, Charlotte; Jobs, Alexander; Schweda, Frank; Kurtz, Lisa; Kurt, Birguel; Sequeira Lopez, Maria L.; Gomez, R. Ariel; van Veen, Toon A.B.; de Wit, Cor; Kurtz, Armin

2011-01-01

Renin-producing juxtaglomerular cells are connected to each other and to endothelial cells of afferent arterioles by gap junctions containing Connexin 40 (Cx40), abundantly expressed by these two cell types. Here, we generated mice with cell-specific deletion of Cx40 in endothelial and in renin-producing cells, as its global deletion caused local dissociation of renin-producing cells from endothelial cells, renin hypersecretion, and hypertension. In mice lacking endothelial Cx40, the blood pressure, renin-producing cell distribution, and the control of renin secretion were similar to wild-type mice. In contrast, mice deficient for Cx40 in renin-producing cells were hypertensive and these cells were ectopically localized. Although plasma renin activity and kidney renin mRNA levels of these mice were not different from controls, the negative regulation of renin secretion by pressure was inverted to a positive feedback in kidneys lacking Cx40 in renin-producing cells. Thus, our findings show that endothelial Cx40 is not essential for the control of renin expression and/or release. Cx40 in renin-producing cells is required for their correct positioning in the juxtaglomerular area and the control of renin secretion by pressure. PMID:20686449

Chemical and physical insight on the local properties of the phosphides XSiP2 (X = Be, Mg, Cd, Zn and Hg) under pressure: from first principles calculations

NASA Astrophysics Data System (ADS)

Ouahrani, Tarik

2013-09-01

Local properties of the XSiP2 (X = Be, Mg, Cd, Zn and Hg) compounds are revisited through the partition of static thermodynamic properties under pressure. We pay attention to the metallization that occurs when the investigated compounds undergo a phase transition from chalcopyrite to the NaCl structure. Electron localization function analysis shows that the local valence basin attractors values decrease as a function of pressure. As the pressure increases, the tetragonal distortion ( c/ a) diminishes while the degree of ionicity enhances. In addition, by means of atom in molecule approach, atomic-like local compressibility and pressures are analyzed. We found that the basins volumes of the investigated compounds in the NaCl phase have lower compressibilities than those in the chalcopyrite phase. According to the predicted core-valence basins, the phosphorus cation is found to be the more affected by the hydrostatic pressure.

Response of local vascular volumes to lower body negative pressure stress

NASA Technical Reports Server (NTRS)

Wolthuis, R. A.; Leblanc, A.; Carpentier, W. A.; Bergman, S. A., Jr.

1975-01-01

The present study involved an intravenous injection of radioactive iodinated serum albumin, equilibration of this isotope within the vascular space, and the continuous measurement of isotope activity over selected anatomical areas before, during and following multiple human LBNP tests. Both rate and magnitude of vascular pooling were distinctly different within each of five selected lower body anatomical areas. In the upper body, all areas except the abdomen showed depletions from their resting vascular volumes during LBNP. The presence of uniquely different pooling patterns in the lower body, the apparent stability of abdominal vascular volumes, and a possible decrease in cerebral blood volume during LBNP represent the major findings of this study.

Wavelet filter analysis of local atmospheric pressure effects in the long-period tidal bands

NASA Astrophysics Data System (ADS)

Hu, X.-G.; Liu, L. T.; Ducarme, B.; Hsu, H. T.; Sun, H.-P.

2006-11-01

It is well known that local atmospheric pressure variations obviously affect the observation of short-period Earth tides, such as diurnal tides, semi-diurnal tides and ter-diurnal tides, but local atmospheric pressure effects on the long-period Earth tides have not been studied in detail. This is because the local atmospheric pressure is believed not to be sufficient for an effective pressure correction in long-period tidal bands, and there are no efficient methods to investigate local atmospheric effects in these bands. The usual tidal analysis software package, such as ETERNA, Baytap-G and VAV, cannot provide detailed pressure admittances for long-period tidal bands. We propose a wavelet method to investigate local atmospheric effects on gravity variations in long-period tidal bands. This method constructs efficient orthogonal filter bank with Daubechies wavelets of high vanishing moments. The main advantage of the wavelet filter bank is that it has excellent low frequency response and efficiently suppresses instrumental drift of superconducting gravimeters (SGs) without using any mathematical model. Applying the wavelet method to the 13-year continuous gravity observations from SG T003 in Brussels, Belgium, we filtered 12 long-period tidal groups into eight narrow frequency bands. Wavelet method demonstrates that local atmospheric pressure fluctuations are highly correlated with the noise of SG measurements in the period band 4-40 days with correlation coefficients higher than 0.95 and local atmospheric pressure variations are the main error source for the determination of the tidal parameters in these bands. We show the significant improvement of long-period tidal parameters provided by wavelet method in term of precision.

Local cooling reduces skin ischemia under surface pressure in rats: an assessment by wavelet analysis of laser Doppler blood flow oscillations.

PubMed

Jan, Yih-Kuen; Lee, Bernard; Liao, Fuyuan; Foreman, Robert D

2012-10-01

The objectives of this study were to investigate the effects of local cooling on skin blood flow response to prolonged surface pressure and to identify associated physiological controls mediating these responses using the wavelet analysis of blood flow oscillations in rats. Twelve Sprague-Dawley rats were randomly assigned to three protocols, including pressure with local cooling (Δt = -10 °C), pressure with local heating (Δt = 10 °C) and pressure without temperature changes. Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The 3 h loading period was divided into non-overlapping 30 min epochs for the analysis of the changes of skin blood flow oscillations using wavelet spectral analysis. The wavelet amplitudes and powers of three frequencies (metabolic, neurogenic and myogenic) of skin blood flow oscillations were calculated. The results showed that after an initial loading period of 30 min, skin blood flow continually decreased under the conditions of pressure with heating and of pressure without temperature changes, but maintained stable under the condition of pressure with cooling. Wavelet analysis revealed that stable skin blood flow under pressure with cooling was attributed to changes in the metabolic and myogenic frequencies. This study demonstrates that local cooling may be useful for reducing ischemia of weight-bearing soft tissues that prevents pressure ulcers.

Local cooling reduces skin ischemia under surface pressure in rats: an assessment by wavelet analysis of laser Doppler blood flow oscillations

PubMed Central

Jan, Yih-Kuen; Lee, Bernard; Liao, Fuyuan; Foreman, Robert D.

2012-01-01

The objectives of this study were to investigate the effects of local cooling on skin blood flow response to prolonged surface pressure and to identify associated physiological controls mediating these responses using wavelet analysis of blood flow oscillations in rats. Twelve Sprague Dawley rats were randomly assigned into three protocols, including pressure with local cooling (Δt= −10°C), pressure with local heating (Δt= 10°C), and pressure without temperature changes. Pressure of 700 mmHg was applied to the right trochanter area of rats for 3 hours. Skin blood flow was measured using laser Doppler flowmetry. The 3-hour loading period was divided into non-overlapping 30 min epochs for analysis of the changes of skin blood flow oscillations using wavelet spectral analysis. The wavelet amplitudes and powers of three frequencies (metabolic, neurogenic and myogenic) of skin blood flow oscillations were calculated. The results showed that after an initial loading period of 30 min, skin blood flow continually decreased in the conditions of pressure with heating and of pressure without temperature changes, but maintained stable in the condition of pressure with cooling. Wavelet analysis revealed that stable skin blood flow under pressure with cooling was attributed to changes in the metabolic and myogenic frequencies. This study demonstrates that local cooling may be useful for reducing ischemia of weight-bearing soft tissues that prevents pressure ulcers. PMID:23010955

Impact Cratering Calculations

NASA Technical Reports Server (NTRS)

Ahrens, Thomas J.

2001-01-01

This research is computational /theoretical and complements the Caltech experimental program. We have developed an understanding of the basic physical processes and produced computational models and implemented these into Eulerian and Lagrangian finite element codes. The key issues we have addressed include the conditions required for: faulting (strain localization), elastic moduli weakening, dynamic weakening (layering elastic instabilities and fluidization), bulking (creation of porosity at zero pressure) and compaction of pores, frictional melting (creation of pseudotachylytes), partial and selective devolatilization of materials (e.g. CaCO3, water/ice mixtures), and debris flows.

Feasibility of Locating Leakages in Sewage Pressure Pipes Using the Distributed Temperature Sensing Technology.

PubMed

Apperl, Benjamin; Pressl, Alexander; Schulz, Karsten

2017-01-01

The cost effective maintenance of underwater pressure pipes for sewage disposal in Austria requires the detection and localization of leakages. Extrusion of wastewater in lakes can heavily influence the water and bathing quality of surrounding waters. The Distributed Temperature Sensing (DTS) technology is a widely used technique for oil and gas pipeline leakage detection. While in pipeline leakage detection, fiber optic cables are installed permanently at the outside or within the protective sheathing of the pipe; this paper aims at testing the feasibility of detecting leakages with temporary introduced fiber optic cable inside the pipe. The detection and localization were tested in a laboratory experiment. The intrusion of water from leakages into the pipe, producing a local temperature drop, served as indicator for leakages. Measurements were taken under varying measurement conditions, including the number of leakages as well as the positioning of the fiber optic cable. Experiments showed that leakages could be detected accurately with the proposed methodology, when measuring resolution, temperature gradient and measurement time were properly selected. Despite the successful application of DTS for leakage detection in this lab environment, challenges in real system applications may arise from temperature gradients within the pipe system over longer distances and the placement of the cable into the real pipe system.

Patterns of population differentiation and natural selection on the celiac disease background risk network.

PubMed

Sams, Aaron; Hawks, John

2013-01-01

Celiac disease is a common small intestinal inflammatory condition induced by wheat gluten and related proteins from rye and barley. Left untreated, the clinical presentation of CD can include failure to thrive, malnutrition, and distension in juveniles. The disease can additionally lead to vitamin deficiencies, anemia, and osteoporosis. Therefore, CD potentially negatively affected fitness in past populations utilizing wheat, barley, and rye. Previous analyses of CD risk variants have uncovered evidence for positive selection on some of these loci. These studies also suggest the possibility that risk for common autoimmune conditions such as CD may be the result of positive selection on immune related loci in the genome to fight infection. Under this evolutionary scenario, disease phenotypes may be a trade-off from positive selection on immunity. If this hypothesis is generally true, we can expect to find a signal of natural selection when we survey across the network of loci known to influence CD risk. This study examines the non-HLA autosomal network of gene loci associated with CD risk in Europe. We reject the null hypothesis of neutrality on this network of CD risk loci. Additionally, we can localize evidence of selection in time and space by adding information from the genome of the Tyrolean Iceman. While we can show significant differentiation between continental regions across the CD network, the pattern of evidence is not consistent with primarily recent (Holocene) selection across this network in Europe. Further localization of ancient selection on this network may illuminate the ecological pressures acting on the immune system during this critically interesting phase of our evolution.

In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor

PubMed Central

Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

2016-01-01

In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery. PMID:27763559

In-Situ Measurement of High-Temperature Proton Exchange Membrane Fuel Cell Stack Using Flexible Five-in-One Micro-Sensor.

PubMed

Lee, Chi-Yuan; Weng, Fang-Bor; Kuo, Yzu-Wei; Tsai, Chao-Hsuan; Cheng, Yen-Ting; Cheng, Chih-Kai; Lin, Jyun-Ting

2016-10-18

In the chemical reaction that proceeds in a high-temperature proton exchange membrane fuel cell stack (HT-PEMFC stack), the internal local temperature, voltage, pressure, flow and current nonuniformity may cause poor membrane material durability and nonuniform fuel distribution, thus influencing the performance and lifetime of the fuel cell stack. In this paper micro-electro-mechanical systems (MEMS) are utilized to develop a high-temperature electrochemical environment-resistant five-in-one micro-sensor embedded in the cathode channel plate of an HT-PEMFC stack, and materials and process parameters are appropriately selected to protect the micro-sensor against failure or destruction during long-term operation. In-situ measurement of the local temperature, voltage, pressure, flow and current distributions in the HT-PEMFC stack is carried out. This integrated micro-sensor has five functions, and is favorably characterized by small size, good acid resistance and temperature resistance, quick response, real-time measurement, and the goal is being able to be put in any place for measurement without affecting the performance of the battery.

Ultra-Sensitive Magnetoresistive Displacement Sensing Device

NASA Technical Reports Server (NTRS)

Olivas, John D. (Inventor); Lairson, Bruce M. (Inventor); Ramesham, Rajeshuni (Inventor)

2003-01-01

An ultrasensitive displacement sensing device for use in accelerometers, pressure gauges, temperature transducers, and the like, comprises a sputter deposited, multilayer, magnetoresistive field sensor with a variable electrical resistance based on an imposed magnetic field. The device detects displacement by sensing changes in the local magnetic field about the magnetoresistive field sensor caused by the displacement of a hard magnetic film on a movable microstructure. The microstructure, which may be a cantilever, membrane, bridge, or other microelement, moves under the influence of an acceleration a known displacement predicted by the configuration and materials selected, and the resulting change in the electrical resistance of the MR sensor can be used to calculate the displacement. Using a micromachining approach, very thin silicon and silicon nitride membranes are fabricated in one preferred embodiment by means of anisotropic etching of silicon wafers. Other approaches include reactive ion etching of silicon on insulator (SOI), or Low Pressure Chemical Vapor Deposition of silicon nitride films over silicon substrates. The device is found to be improved with the use of giant magnetoresistive elements to detect changes in the local magnetic field.

The accuracy of the compressible Reynolds equation for predicting the local pressure in gas-lubricated textured parallel slider bearings

PubMed Central

Qiu, Mingfeng; Bailey, Brian N.; Stoll, Rob

2014-01-01

The validity of the compressible Reynolds equation to predict the local pressure in a gas-lubricated, textured parallel slider bearing is investigated. The local bearing pressure is numerically simulated using the Reynolds equation and the Navier-Stokes equations for different texture geometries and operating conditions. The respective results are compared and the simplifying assumptions inherent in the application of the Reynolds equation are quantitatively evaluated. The deviation between the local bearing pressure obtained with the Reynolds equation and the Navier-Stokes equations increases with increasing texture aspect ratio, because a significant cross-film pressure gradient and a large velocity gradient in the sliding direction develop in the lubricant film. Inertia is found to be negligible throughout this study. PMID:25049440

Microplasma Induced Cell Morphological Changes and Apoptosis of Ex Vivo Cultured Human Anterior Lens Epithelial Cells – Relevance to Capsular Opacification

PubMed Central

Hojnik, Nataša; Filipič, Gregor; Lazović, Saša; Vesel, Alenka; Primc, Gregor; Mozetič, Miran; Hawlina, Marko; Petrovski, Goran; Cvelbar, Uroš

2016-01-01

Inducing selective or targeted cell apoptosis without affecting large number of neighbouring cells remains a challenge. A plausible method for treatment of posterior capsular opacification (PCO) due to remaining lens epithelial cells (LECs) by reactive chemistry induced by localized single electrode microplasma discharge at top of a needle-like glass electrode with spot size ~3 μm is hereby presented. The focused and highly-localized atmospheric pressure microplasma jet with electrode discharge could induce a dose-dependent apoptosis in selected and targeted individual LECs, which could be confirmed by real-time monitoring of the morphological and structural changes at cellular level. Direct cell treatment with microplasma inside the medium appeared more effective in inducing apoptosis (caspase 8 positivity and DNA fragmentation) at a highly targeted cell level compared to treatment on top of the medium (indirect treatment). Our results show that single cell specific micropipette plasma can be used to selectively induce demise in LECs which remain in the capsular bag after cataract surgery and thus prevent their migration (CXCR4 positivity) to the posterior lens capsule and PCO formation. PMID:27832099

Selective pressure against horizontally acquired prokaryotic genes as a driving force of plastid evolution.

PubMed

Llorente, Briardo; de Souza, Flavio S J; Soto, Gabriela; Meyer, Cristian; Alonso, Guillermo D; Flawiá, Mirtha M; Bravo-Almonacid, Fernando; Ayub, Nicolás D; Rodríguez-Concepción, Manuel

2016-01-11

The plastid organelle comprises a high proportion of nucleus-encoded proteins that were acquired from different prokaryotic donors via independent horizontal gene transfers following its primary endosymbiotic origin. What forces drove the targeting of these alien proteins to the plastid remains an unresolved evolutionary question. To better understand this process we screened for suitable candidate proteins to recapitulate their prokaryote-to-eukaryote transition. Here we identify the ancient horizontal transfer of a bacterial polyphenol oxidase (PPO) gene to the nuclear genome of an early land plant ancestor and infer the possible mechanism behind the plastidial localization of the encoded enzyme. Arabidopsis plants expressing PPO versions either lacking or harbouring a plastid-targeting signal allowed examining fitness consequences associated with its subcellular localization. Markedly, a deleterious effect on plant growth was highly correlated with PPO activity only when producing the non-targeted enzyme, suggesting that selection favoured the fixation of plastid-targeted protein versions. Our results reveal a possible evolutionary mechanism of how selection against heterologous genes encoding cytosolic proteins contributed in incrementing plastid proteome complexity from non-endosymbiotic gene sources, a process that may also impact mitochondrial evolution.

Adaptations to climate-mediated selective pressures in sheep.

PubMed

Lv, Feng-Hua; Agha, Saif; Kantanen, Juha; Colli, Licia; Stucki, Sylvie; Kijas, James W; Joost, Stéphane; Li, Meng-Hua; Ajmone Marsan, Paolo

2014-12-01

Following domestication, sheep (Ovis aries) have become essential farmed animals across the world through adaptation to a diverse range of environments and varied production systems. Climate-mediated selective pressure has shaped phenotypic variation and has left genetic "footprints" in the genome of breeds raised in different agroecological zones. Unlike numerous studies that have searched for evidence of selection using only population genetics data, here, we conducted an integrated coanalysis of environmental data with single nucleotide polymorphism (SNP) variation. By examining 49,034 SNPs from 32 old, autochthonous sheep breeds that are adapted to a spectrum of different regional climates, we identified 230 SNPs with evidence for selection that is likely due to climate-mediated pressure. Among them, 189 (82%) showed significant correlation (P ≤ 0.05) between allele frequency and climatic variables in a larger set of native populations from a worldwide range of geographic areas and climates. Gene ontology analysis of genes colocated with significant SNPs identified 17 candidates related to GTPase regulator and peptide receptor activities in the biological processes of energy metabolism and endocrine and autoimmune regulation. We also observed high linkage disequilibrium and significant extended haplotype homozygosity for the core haplotype TBC1D12-CH1 of TBC1D12. The global frequency distribution of the core haplotype and allele OAR22_18929579-A showed an apparent geographic pattern and significant (P ≤ 0.05) correlations with climatic variation. Our results imply that adaptations to local climates have shaped the spatial distribution of some variants that are candidates to underpin adaptive variation in sheep. © The Author 2014. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Identification of a Novel Lysosomal Trafficking Peptide using Phage Display Biopanning Coupled with Endocytic Selection Pressure

PubMed Central

2015-01-01

Methods to select ligands that accumulate specifically in cancer cells and traffic through a defined endocytic pathway may facilitate rapid pairing of ligands with linkers suitable for drug conjugate therapies. We performed phage display biopanning on cancer cells that are treated with selective inhibitors of a given mechanism of endocytosis. Using chlorpromazine to inhibit clathrin-mediated endocytosis in H1299 nonsmall cell lung cancer cells, we identified two clones, ATEPRKQYATPRVFWTDAPG (15.1) and a novel peptide LQWRRDDNVHNFGVWARYRL (H1299.3). The peptides segregate by mechanism of endocytosis and subsequent location of subcellular accumulation. The H1299.3 peptide primarily utilizes clathrin-mediated endocytosis and colocalizes with Lamp1, a lysosomal marker. Conversely, the 15.1 peptide is clathrin-independent and localizes to a perinuclear region. Thus, this novel phage display scheme allows for selection of peptides that selectively internalize into cells via a known mechanism of endocytosis. These types of selections may allow for better matching of linker with targeting ligand by selecting ligands that internalize and traffic to known subcellular locations. PMID:25188559

Flight testing of a luminescent surface pressure sensor

NASA Technical Reports Server (NTRS)

Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

1992-01-01

NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

Snake Envenomation Causing Distant Tracheal Myonecrosis

PubMed Central

Khimani, Amina; Mcnierney, Afton; Surani, Sara; Surani, Salim

2013-01-01

Snakebites are often believed to be poisonous. However, this is not always the case. In fact, each bite differs from snake to snake, depending on if the snake is poisonous and if there is envenomation. Venom in pit viper snakebites is often associated with local necrosis. The abundant literature selections and research articles justify local myonecrosis due to envenomation, but there is not much in the literature regarding myonecrosis at a site distant from the snakebite. We hereby present a case of a 42-year-old man who was transferred to our emergency department after a rattlesnake bit him twice. The patient, besides developing local myonecrosis at the site of the snakebite, developed necrosis of the scrotum as well as tracheal pressure myonecrosis at the site of the endotracheal tube balloon. In this review, we will attempt to discuss the myonecrosis pathophysiology and management related to the rattle snakebite. PMID:24083047

Effect of atmospheric-pressure plasma treatment on the adhesion properties of a thin adhesive layer in a selective transfer process

NASA Astrophysics Data System (ADS)

Yoon, Min-Ah; Kim, Chan; Hur, Min; Kang, Woo Seok; Kim, Jaegu; Kim, Jae-Hyun; Lee, Hak-Joo; Kim, Kwang-Seop

2018-01-01

The adhesion between a stamp and thin film devices is crucial for their transfer on a flexible substrate. In this paper, a thin adhesive silicone layer on the stamp was treated by atmospheric pressure plasma to locally control the adhesion strength for the selective transfer. The adhesion strength of the silicone layer was significantly reduced after the plasma treatment, while its surface energy was increased. To understand the inconsistency between the adhesion strength and surface energy changes, the surface properties of the silicone layer were characterized using nanoindentation and X-ray photoelectron spectroscopy. These techniques revealed that a thin, hard, silica-like layer had formed on the surface from plasma-enhanced oxidation. This layer played an important role in decreasing the contact area and increasing the interfacial slippage, resulting in decreased adhesion. As a practical application, the transfer process was demonstrated on GaN LEDs that had been previously delaminated by a laser lift-off (LLO) process. Although the LEDs were not transferred onto the treated adhesive layer due to the reduced adhesion, the untreated adhesive layer could readily pick up the LEDs. It is expected that this simple method of controlling the adhesion of a stamp with a thin adhesive layer would enable a continuous, selective and large-scale roll-to-roll selective transfer process and thereby advance the development of flexible, stretchable and wearable electronics.

Signatures of selection in the Iberian honey bee (Apis mellifera iberiensis) revealed by a genome scan analysis of single nucleotide polymorphisms.

PubMed

Chávez-Galarza, Julio; Henriques, Dora; Johnston, J Spencer; Azevedo, João C; Patton, John C; Muñoz, Irene; De la Rúa, Pilar; Pinto, M Alice

2013-12-01

Understanding the genetic mechanisms of adaptive population divergence is one of the most fundamental endeavours in evolutionary biology and is becoming increasingly important as it will allow predictions about how organisms will respond to global environmental crisis. This is particularly important for the honey bee, a species of unquestionable ecological and economical importance that has been exposed to increasing human-mediated selection pressures. Here, we conducted a single nucleotide polymorphism (SNP)-based genome scan in honey bees collected across an environmental gradient in Iberia and used four FST -based outlier tests to identify genomic regions exhibiting signatures of selection. Additionally, we analysed associations between genetic and environmental data for the identification of factors that might be correlated or act as selective pressures. With these approaches, 4.4% (17 of 383) of outlier loci were cross-validated by four FST -based methods, and 8.9% (34 of 383) were cross-validated by at least three methods. Of the 34 outliers, 15 were found to be strongly associated with one or more environmental variables. Further support for selection, provided by functional genomic information, was particularly compelling for SNP outliers mapped to different genes putatively involved in the same function such as vision, xenobiotic detoxification and innate immune response. This study enabled a more rigorous consideration of selection as the underlying cause of diversity patterns in Iberian honey bees, representing an important first step towards the identification of polymorphisms implicated in local adaptation and possibly in response to recent human-mediated environmental changes. © 2013 John Wiley & Sons Ltd.

Comparison of the effect of two damper sizes on the performance of a low-solidity axial-flow transonic compressor rotor

NASA Technical Reports Server (NTRS)

Lewis, G. W., Jr.; Urasek, D. C.

1972-01-01

The experimental performance of a 20-inch-diameter axial-flow transonic compressor rotor with small dampers is presented. The compressor rotor was tested earlier with large dampers which were twice in size, and comparisons of overall performance and radial distributions of selected flow and performance parameters are made. The rotor with small dampers experienced lower losses in the damper region which resulted in locally higher values of temperature rise efficiency and total pressure ratio. However, there was no appreciable effect on overall efficiency and pressure ratio. A greater stall margin was measured for the rotor with small dampers at design speed, but at 70 and 90 percent of design speed the rotor with large dampers had somewhat greater flow range.

Are There Differences in Antibiotic Use Between the Recent-Immigrants from Mainland China and the Local-Born in Hong Kong?

PubMed

Wun, Yuk Tsan; Lam, Tai Pong; Lam, Kwok Fai; Ho, Pak Leung; Yung, Wai Hung Raymond

2015-08-01

Immigrants, especially the first-generation, were thought to have different knowledge, attitudes and practice (KAP) with antibiotics. Doctors often perceived extra pressure from them to prescribe antibiotics. To test these perceptions, we studied the difference in KAP with antibiotics between the recent-immigrants from mainland China and the local-born of Hong Kong-places with significantly different healthcare and socio-economic systems. Focus groups (including one specific group of recent-immigrants) with 56 participants and territory-wide telephone questionnaire survey with 2,471 randomly selected respondents. Recent-immigrants shared similar KAP with the local-born. After adjustment for age, sex and education, the main significant difference was the new-immigrants' behaviour of acquiring antibiotics without prescription and keeping the leftover. They, like the local-born, preferred doctors who prescribed antibiotics cautiously. Immigration status could be the surrogate for age, sex and education in the KAP with antibiotics. For antibiotic use, health education and patient care could be similar between the recent-immigrants and the local-born.

Investigation of local evaporation flux and vapor-phase pressure at an evaporative droplet interface.

PubMed

Duan, Fei; Ward, C A

2009-07-07

In the steady-state experiments of water droplet evaporation, when the throat was heating at a stainless steel conical funnel, the interfacial liquid temperature was found to increase parabolically from the center line to the rim of the funnel with the global vapor-phase pressure at around 600 Pa. The energy conservation analysis at the interface indicates that the energy required for evaporation is maintained by thermal conduction to the interface from the liquid and vapor phases, thermocapillary convection at interface, and the viscous dissipation globally and locally. The local evaporation flux increases from the center line to the periphery as a result of multiple effects of energy transport at the interface. The local vapor-phase pressure predicted from statistical rate theory (SRT) is also found to increase monotonically toward the interface edge from the center line. However, the average value of the local vapor-phase pressures is in agreement with the measured global vapor-phase pressure within the measured error bar.

Overpressure and hydrocarbon accumulations in Tertiary strata, Gulf Coast of Louisiana

USGS Publications Warehouse

Nelson, Philip H.

2012-01-01

Many oil and gas reservoirs in Tertiary strata of southern Louisiana are located close to the interface between a sand-rich, normally pressured sequence and an underlying sand-poor, overpressured sequence. This association, recognized for many years by Gulf Coast explorationists, is revisited here because of its relevance to an assessment of undiscovered oil and gas potential in the Gulf Coast of Louisiana. The transition from normally pressured to highly overpressured sediments is documented by converting mud weights to pressure, plotting all pressure data from an individual field as a function of depth, and selecting a top and base of the pressure transition zone. Vertical extents of pressure transition zones in 34 fields across southern onshore Louisiana range from 300 to 9000 ft and are greatest in younger strata and in the larger fields. Display of pressure transition zones on geologic cross sections illustrates the relative independence of the depth of the pressure transition zone and geologic age. Comparison of the depth distribution of pressure transition zones with production intervals confirms previous findings that production intervals generally overlap the pressure transition zone in depth and that the median production depth lies above the base of the pressure transition zone in most fields. However, in 11 of 55 fields with deep drilling, substantial amounts of oil and gas have been produced from depths deeper than 2000 ft below the base of the pressure transition zone. Mud-weight data in 7 fields show that "local" pressure gradients range from 0.91 to 1.26 psi/ft below the base of the pressure transition zone. Pressure gradients are higher and computed effective stress gradients are negative in younger strata in coastal areas, indicating that a greater potential for fluid and sediment movement exists there than in older Tertiary strata.

Technology selection for MSW treatment in Altiplano areas using FMDM.

PubMed

Jiang, Jianguo; Lou, Zhiying; Hg, Siio; Duo, Ji; Li, Zhong

2009-10-01

There are special requirements for municipal solid waste (MSW) treatment caused by lower oxygen content and atmospheric pressure on the Altiplano. The intention of this paper was to analyse the applicability of various technologies to MSW treatment in the Altiplano and select the best one based on the current MSW collection modes and technical levels, using the Fuzzy Mathematical Decision Method (FMDM). Technologies including landfill, incineration, composting, and anaerobic digestion (AD) were compared. The results of the studies showed that AD technology is a new technology which is attractive in economic terms and helpful for environmental harmony. AD can solve the difficulties caused by a high content of organic matter in the MSW, lower atmospheric pressure and oxygen content on the Altiplano. Moreover, it can achieve reduction and recycling of the waste, thereby saving space for treatment and disposal. Using this technology, renewable energy can be recovered to save conventional fuel consumption and the emission of greenhouse gases can be reduced to improve the conservation of the local ecosystem. Putting AD into practice in the Altiplano may be the preferred method of MSW treatment.

Non-Random Inversion Landscapes in Prokaryotic Genomes Are Shaped by Heterogeneous Selection Pressures.

PubMed

Repar, Jelena; Warnecke, Tobias

2017-08-01

Inversions are a major contributor to structural genome evolution in prokaryotes. Here, using a novel alignment-based method, we systematically compare 1,651 bacterial and 98 archaeal genomes to show that inversion landscapes are frequently biased toward (symmetric) inversions around the origin-terminus axis. However, symmetric inversion bias is not a universal feature of prokaryotic genome evolution but varies considerably across clades. At the extremes, inversion landscapes in Bacillus-Clostridium and Actinobacteria are dominated by symmetric inversions, while there is little or no systematic bias favoring symmetric rearrangements in archaea with a single origin of replication. Within clades, we find strong but clade-specific relationships between symmetric inversion bias and different features of adaptive genome architecture, including the distance of essential genes to the origin of replication and the preferential localization of genes on the leading strand. We suggest that heterogeneous selection pressures have converged to produce similar patterns of structural genome evolution across prokaryotes. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Optimization of stable quadruped locomotion using mutual information

NASA Astrophysics Data System (ADS)

Silva, Pedro; Santos, Cristina P.; Polani, Daniel

2013-10-01

Central Pattern Generators (CPG)s have been widely used in the field of robotics to address the task of legged locomotion generation. The adequate configuration of these structures for a given platform can be accessed through evolutionary strategies, according to task dependent selection pressures. Information driven evolution, accounts for information theoretical measures as selection pressures, as an alternative to a fully task dependent selection pressure. In this work we exploit this concept and evaluate the use of mean Mutual Information, as a selection pressure towards a CPG configuration capable of faster, yet more coordinated and stabler locomotion than when only a task dependent selection pressure is used.

The role of protozoa-driven selection in shaping human genetic variability.

PubMed

Pozzoli, Uberto; Fumagalli, Matteo; Cagliani, Rachele; Comi, Giacomo P; Bresolin, Nereo; Clerici, Mario; Sironi, Manuela

2010-03-01

Protozoa exert a strong selective pressure in humans. The selection signatures left by these pathogens can be exploited to identify genetic modulators of infection susceptibility. We show that protozoa diversity in different geographic locations is a good measure of protozoa-driven selective pressure; protozoa diversity captured selection signatures at known malaria resistance loci and identified several selected single nucleotide polymorphisms in immune and hemolytic anemia genes. A genome-wide search enabled us to identify 5180 variants mapping to 1145 genes that are subjected to protozoa-driven selective pressure. We provide a genome-wide estimate of protozoa-driven selective pressure and identify candidate susceptibility genes for protozoa-borne diseases. Copyright 2010 Elsevier Ltd. All rights reserved.

Force reduction induced by unidirectional transversal muscle loading is independent of local pressure.

PubMed

Siebert, Tobias; Rode, Christian; Till, Olaf; Stutzig, Norman; Blickhan, Reinhard

2016-05-03

Transversal unidirectional compression applied to muscles via external loading affects muscle contraction dynamics in the longitudinal direction. A recent study reported decreasing longitudinal muscle forces with increasing transversal load applied with a constant contact area (i.e., leading to a simultaneous increase in local pressure). To shed light on these results, we examine whether the decrease in longitudinal force depends on the load, the local pressure, or both. To this end, we perform isometric experiments on rat M. gastrocnemius medialis without and with transversal loading (i) changing the local pressure from 1.1-3.2Ncm(-2) (n=9) at a constant transversal load (1.62N) and (ii) increasing the transversal load (1.15-3.45N) at a constant local pressure of 2.3Ncm(-2) (n=7). While we did not note changes in the decrease in longitudinal muscle force in the first experiment, the second experiment resulted in an almost-linear reduction of longitudinal force between 7.5±0.6% and 14.1±1.7%. We conclude that the observed longitudinal force reduction is not induced by local effects such as malfunction of single muscle compartments, but that similar internal stress conditions and myofilament configurations occur when the local pressure changes given a constant load. The decreased longitudinal force may be explained by increased internal pressure and a deformed myofilament lattice that is likely associated with the decomposition of cross-bridge forces on the one hand and the inhibition of cross-bridges on the other hand. Copyright © 2016 Elsevier Ltd. All rights reserved.

BreathSens: A Continuous On-Bed Respiratory Monitoring System With Torso Localization Using an Unobtrusive Pressure Sensing Array.

PubMed

Liu, Jason J; Huang, Ming-Chun; Xu, Wenyao; Zhang, Xiaoyi; Stevens, Luke; Alshurafa, Nabil; Sarrafzadeh, Majid

2015-09-01

The ability to continuously monitor respiration rates of patients in homecare or in clinics is an important goal. Past research showed that monitoring patient breathing can lower the associated mortality rates for long-term bedridden patients. Nowadays, in-bed sensors consisting of pressure sensitive arrays are unobtrusive and are suitable for deployment in a wide range of settings. Such systems aim to extract respiratory signals from time-series pressure sequences. However, variance of movements, such as unpredictable extremities activities, affect the quality of the extracted respiratory signals. BreathSens, a high-density pressure sensing system made of e-Textile, profiles the underbody pressure distribution and localizes torso area based on the high-resolution pressure images. With a robust bodyparts localization algorithm, respiratory signals extracted from the localized torso area are insensitive to arbitrary extremities movements. In a study of 12 subjects, BreathSens demonstrated its respiratory monitoring capability with variations of sleep postures, locations, and commonly tilted clinical bed conditions.

Near 7-day response of ocean bottom pressure to atmospheric surface pressure and winds in the northern South China Sea

NASA Astrophysics Data System (ADS)

Zhang, Kun; Zhu, Xiao-Hua; Zhao, Ruixiang

2018-02-01

Ocean bottom pressures, observed by five pressure-recording inverted echo sounders (PIESs) from October 2012 to July 2014, exhibit strong near 7-day variability in the northern South China Sea (SCS) where long-term in situ bottom pressure observations are quite sparse. This variability was strongest in October 2013 during the near two years observation period. By joint analysis with European Center for Medium-Range Weather Forecasts (ECMWF) data, it is shown that the near 7-day ocean bottom pressure variability is closely related to the local atmospheric surface pressure and winds. Within a period band near 7 days, there are high coherences, exceeding 95% significance level, of observed ocean bottom pressure with local atmospheric surface pressure and with both zonal and meridional components of the wind. Ekman pumping/suction caused by the meridional component of the wind in particular, is suggested as one driving mechanism. A Kelvin wave response to the near 7-day oscillation would propagate down along the continental slope, observed at the Qui Nhon in the Vietnam. By multiple and partial coherence analyses, we find that local atmospheric surface pressure and Ekman pumping/suction show nearly equal influence on ocean bottom pressure variability at near 7-day periods. A schematic diagram representing an idealized model gives us a possible mechanism to explain the relationship between ocean bottom pressure and local atmospheric forcing at near 7-day periods in the northern SCS.

Rural Schoolteachers and the Pressures of Community Life: Local and Cosmopolitan Coping Strategies in Mid-Twentieth-Century Finland

ERIC Educational Resources Information Center

Anttila, Erkko; Vaananen, Ari

2013-01-01

This article discusses rural schoolteachers' relationships with local village communities in mid-twentieth-century Finland. At the time, Finnish rural teachers were typically very public figures in their local community. To deal with the pressures of their position, teachers resorted to coping strategies which the authors name "local"…

Evolution of complex density-dependent dispersal strategies.

PubMed

Parvinen, Kalle; Seppänen, Anne; Nagy, John D

2012-11-01

The question of how dispersal behavior is adaptive and how it responds to changes in selection pressure is more relevant than ever, as anthropogenic habitat alteration and climate change accelerate around the world. In metapopulation models where local populations are large, and thus local population size is measured in densities, density-dependent dispersal is expected to evolve to a single-threshold strategy, in which individuals stay in patches with local population density smaller than a threshold value and move immediately away from patches with local population density larger than the threshold. Fragmentation tends to convert continuous populations into metapopulations and also to decrease local population sizes. Therefore we analyze a metapopulation model, where each patch can support only a relatively small local population and thus experience demographic stochasticity. We investigated the evolution of density-dependent dispersal, emigration and immigration, in two scenarios: adult and natal dispersal. We show that density-dependent emigration can also evolve to a nonmonotone, "triple-threshold" strategy. This interesting phenomenon results from an interplay between the direct and indirect benefits of dispersal and the costs of dispersal. We also found that, compared to juveniles, dispersing adults may benefit more from density-dependent vs. density-independent dispersal strategies.

Local structural distortion and electrical transport properties of Bi(Ni 1/2Ti 1/2)O 3 perovskite under high pressure

DOE PAGES

Zhu, Jinlong; Yang, Liuxiang; Wang, Hsiu -Wen; ...

2015-12-16

Perovskite-structure materials generally exhibit local structural distortions that are distinct from long-range, average crystal structure. The characterization of such distortion is critical to understanding the structural and physical properties of materials. In this work, we combined Pair Distribution Function (PDF) technique with Raman spectroscopy and electrical resistivity measurement to study Bi(Ni 1/2Ti 1/2)O 3 perovskite under high pressure. PDF analysis reveals strong local structural distortion at ambient conditions. As pressure increases, the local structure distortions are substantially suppressed and eventually vanish around 4 GPa, leading to concurrent changes in the electronic band structure and anomalies in the electrical resistivity. Wemore » find, consistent with PDF analysis, Raman spectroscopy data suggest that the local structure changes to a higher ordered state at pressures above 4 GPa.« less

Local structural distortion and electrical transport properties of Bi(Ni1/2Ti1/2)O3 perovskite under high pressure.

PubMed

Zhu, Jinlong; Yang, Liuxiang; Wang, Hsiu-Wen; Zhang, Jianzhong; Yang, Wenge; Hong, Xinguo; Jin, Changqing; Zhao, Yusheng

2015-12-16

Perovskite-structure materials generally exhibit local structural distortions that are distinct from long-range, average crystal structure. The characterization of such distortion is critical to understanding the structural and physical properties of materials. In this work, we combined Pair Distribution Function (PDF) technique with Raman spectroscopy and electrical resistivity measurement to study Bi(Ni1/2Ti1/2)O3 perovskite under high pressure. PDF analysis reveals strong local structural distortion at ambient conditions. As pressure increases, the local structure distortions are substantially suppressed and eventually vanish around 4 GPa, leading to concurrent changes in the electronic band structure and anomalies in the electrical resistivity. Consistent with PDF analysis, Raman spectroscopy data suggest that the local structure changes to a higher ordered state at pressures above 4 GPa.

Tumor evolution in space: the effects of competition colonization tradeoffs on tumor invasion dynamics.

PubMed

Orlando, Paul A; Gatenby, Robert A; Brown, Joel S

2013-01-01

We apply competition colonization tradeoff models to tumor growth and invasion dynamics to explore the hypothesis that varying selection forces will result in predictable phenotypic differences in cells at the tumor invasive front compared to those in the core. Spatially, ecologically, and evolutionarily explicit partial differential equation models of tumor growth confirm that spatial invasion produces selection pressure for motile phenotypes. The effects of the invasive phenotype on normal adjacent tissue determine the patterns of growth and phenotype distribution. If tumor cells do not destroy their environment, colonizer and competitive phenotypes coexist with the former localized at the invasion front and the latter, to the tumor interior. If tumors cells do destroy their environment, then cell motility is strongly selected resulting in accelerated invasion speed with time. Our results suggest that the widely observed genetic heterogeneity within cancers may not be the stochastic effect of random mutations. Rather, it may be the consequence of predictable variations in environmental selection forces and corresponding phenotypic adaptations.

Tumor Evolution in Space: The Effects of Competition Colonization Tradeoffs on Tumor Invasion Dynamics

PubMed Central

Orlando, Paul A.; Gatenby, Robert A.; Brown, Joel S.

2013-01-01

We apply competition colonization tradeoff models to tumor growth and invasion dynamics to explore the hypothesis that varying selection forces will result in predictable phenotypic differences in cells at the tumor invasive front compared to those in the core. Spatially, ecologically, and evolutionarily explicit partial differential equation models of tumor growth confirm that spatial invasion produces selection pressure for motile phenotypes. The effects of the invasive phenotype on normal adjacent tissue determine the patterns of growth and phenotype distribution. If tumor cells do not destroy their environment, colonizer and competitive phenotypes coexist with the former localized at the invasion front and the latter, to the tumor interior. If tumors cells do destroy their environment, then cell motility is strongly selected resulting in accelerated invasion speed with time. Our results suggest that the widely observed genetic heterogeneity within cancers may not be the stochastic effect of random mutations. Rather, it may be the consequence of predictable variations in environmental selection forces and corresponding phenotypic adaptations. PMID:23508890

Multiscale landscape genomic models to detect signatures of selection in the alpine plant Biscutella laevigata.

PubMed

Leempoel, Kevin; Parisod, Christian; Geiser, Céline; Joost, Stéphane

2018-02-01

Plant species are known to adapt locally to their environment, particularly in mountainous areas where conditions can vary drastically over short distances. The climate of such landscapes being largely influenced by topography, using fine-scale models to evaluate environmental heterogeneity may help detecting adaptation to micro-habitats. Here, we applied a multiscale landscape genomic approach to detect evidence of local adaptation in the alpine plant Biscutella laevigata . The two gene pools identified, experiencing limited gene flow along a 1-km ridge, were different in regard to several habitat features derived from a very high resolution (VHR) digital elevation model (DEM). A correlative approach detected signatures of selection along environmental gradients such as altitude, wind exposure, and solar radiation, indicating adaptive pressures likely driven by fine-scale topography. Using a large panel of DEM-derived variables as ecologically relevant proxies, our results highlighted the critical role of spatial resolution. These high-resolution multiscale variables indeed indicate that the robustness of associations between genetic loci and environmental features depends on spatial parameters that are poorly documented. We argue that the scale issue is critical in landscape genomics and that multiscale ecological variables are key to improve our understanding of local adaptation in highly heterogeneous landscapes.

Local time asymmetries and toroidal field line resonances: Global magnetospheric modeling in SWMF

NASA Astrophysics Data System (ADS)

Ellington, S. M.; Moldwin, M. B.; Liemohn, M. W.

2016-03-01

We present evidence of resonant wave-wave coupling via toroidal field line resonance (FLR) signatures in the Space Weather Modeling Framework's (SWMF) global, terrestrial magnetospheric model in one simulation driven by a synthetic upstream solar wind with embedded broadband dynamic pressure fluctuations. Using in situ, stationary point measurements of the radial electric field along the 1500 LT meridian, we show that SWMF reproduces a multiharmonic, continuous distribution of FLRs exemplified by 180° phase reversals and amplitude peaks across the resonant L shells. By linearly increasing the amplitude of the dynamic pressure fluctuations in time, we observe a commensurate increase in the amplitude of the radial electric and azimuthal magnetic field fluctuations, which is consistent with the solar wind driver being the dominant source of the fast mode energy. While we find no discernible local time changes in the FLR frequencies despite large-scale, monotonic variations in the dayside equatorial mass density, in selectively sampling resonant points and examining spectral resonance widths, we observe significant radial, harmonic, and time-dependent local time asymmetries in the radial electric field amplitudes. A weak but persistent local time asymmetry exists in measures of the estimated coupling efficiency between the fast mode and toroidal wave fields, which exhibits a radial dependence consistent with the coupling strength examined by Mann et al. (1999) and Zhu and Kivelson (1988). We discuss internal structural mechanisms and additional external energy sources that may account for these asymmetries as we find that local time variations in the strength of the compressional driver are not the predominant source of the FLR amplitude asymmetries. These include resonant mode coupling of observed Kelvin-Helmholtz surface wave generated Pc5 band ultralow frequency pulsations, local time differences in local ionospheric dampening rates, and variations in azimuthal mode number, which may impact the partitioning of spectral energy between the toroidal and poloidal wave modes.

Effect of dexmedetomidine injected into the oral mucosa in combination with lidocaine on local anesthetic potency in humans: a crossover double-blind study.

PubMed

Yamane, Ayaka; Higuchi, Hitoshi; Tomoyasu, Yumiko; Ishii-Maruhama, Minako; Maeda, Shigeru; Miyawaki, Takuya

2015-04-01

Recently, attention has been paid to dexmedetomidine, a selective α-2 adrenoceptor agonist, as a possible additive for local anesthesia. However, the effect of locally injected dexmedetomidine on the anesthetic action in humans has not fully been clarified. Thus, the purpose of the present study was to evaluate the effect of dexmedetomidine injected into the oral mucosa in combination with lidocaine on local anesthetic potency in humans. Twenty healthy volunteers were included in the present crossover double-blinded study. Lidocaine solution or lidocaine plus dexmedetomidine solution was submucosally injected into the alveolar mucosa in a crossover and double-blinded manner. The local anesthetic effect of the solutions was evaluated by measuring the current perception threshold (CPT) in the oral mucosa for 120 minutes after injection. Furthermore, the sedation level, blood pressure, and heart rate of the volunteers were evaluated. For statistical analysis, the Wilcoxon signed rank test and 2-way repeated measures analysis of variation were used. The CPT was increased with the 2 solutions and peaked 10 minutes after injection. CPT values 10 and 20 minutes after injection of lidocaine plus dexmedetomidine solution were considerably higher than those with lidocaine solution. The duration of an important increase in the CPT after injection with lidocaine plus dexmedetomidine solution was longer than that with lidocaine. Furthermore, the area under the time curve of CPT was considerably higher with lidocaine plus dexmedetomidine solution than with lidocaine solution. No volunteer showed a change in sedation level, blood pressure, or heart rate after injection with either test solution throughout the experiment. The present study showed that a combination of dexmedetomidine plus lidocaine considerably enhances the local anesthetic potency of lidocaine without any major influences on the cardiovascular system when locally injected into the oral mucosa. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.

Tracking a Solar Wind Dynamic Pressure Pulses' Impact Through the Magnetosphere Using the Heliophysics System Observatory

NASA Astrophysics Data System (ADS)

Vidal-Luengo, S.; Moldwin, M.

2017-12-01

During northward Interplanetary Magnetic Field (IMF) Bz conditions, the magnetosphere acts as a closed "cavity" and reacts to solar wind dynamic pressure pulses more simply than during southward IMF conditions. Effects of solar wind dynamic pressure have been observed as geomagnetic lobe compressions depending on the characteristics of the pressure pulse and the spacecraft location. One of the most important aspects of this study is the incorporation of simultaneous observations by different missions, such as WIND, CLUSTER, THEMIS, MMS, Van Allen Probes and GOES as well as magnetometer ground stations that allow us to map the magnetosphere response at different locations during the propagation of a pressure pulse. In this study we used the SYM-H as an indicator of dynamic pressure pulses occurrence from 2007 to 2016. The selection criteria for events are: (1) the increase in the index must be bigger than 10 [nT] and (2) the rise time must be in less than 5 minutes. Additionally, the events must occur under northward IMF and at the same time at least one spacecraft has to be located in the magnetosphere nightside. Using this methodology we found 66 pressure pulse events for analysis. Most of them can be classified as step function pressure pulses or as sudden impulses (increase followed immediately by a decrease of the dynamic pressure). Under these two categories the results show some systematic signatures depending of the location of the spacecraft. For both kind of pressure pulse signatures, compressions are observed on the dayside. However, on the nightside compressions and/or South-then-North magnetic signatures can be observed for step function like pressure pulses, meanwhile for the sudden impulse kind of pressure pulses the magnetospheric response seems to be less global and more dependent on the local conditions.

Non-local rheology for dense granular flows in avalanches

NASA Astrophysics Data System (ADS)

Izzet, Adrien; Clement, Eric; Andreotti, Bruno

A local constitutive relation was proposed to describe dense granular flows (GDR MiDi, EPJE 2004). It provides a rather good prediction of the flowing regime but does not foresee the existence of a ``creep regime'' as observed by Komatsu et al. (PRL 2001). In the context of a 2D shear cell, a relaxation length for the velocity profile was measured (Bouzid et al., PRL 2013) which confirmed the existence of a flow below the standard Coulomb yield threshold. A correction for the local rheology was proposed. To test further this non-local constitutive relation, we built an inclined narrow channel within which we monitor the flow from the side. We managed to observe the ``creep regime'' over five orders of magnitude in velocity and fit the velocity profiles in the depth with an asymptotic solution of the non-local equation. However, the boundary condition at the free surface needs to be selected in order to calibrate the non-local rheology over the whole range of stresses in the system. In this perspective, we complement the experimental results with 2D simulations of hard and frictional discs on an inclined plane in which we introduce a surface friction force proportional to the effective pressure in the granular. We analyze these results in the light of the non-local rheology.

Genomic Signatures of Selective Pressures and Introgression from Archaic Hominins at Human Innate Immunity Genes

PubMed Central

Deschamps, Matthieu; Laval, Guillaume; Fagny, Maud; Itan, Yuval; Abel, Laurent; Casanova, Jean-Laurent; Patin, Etienne; Quintana-Murci, Lluis

2016-01-01

Human genes governing innate immunity provide a valuable tool for the study of the selective pressure imposed by microorganisms on host genomes. A comprehensive, genome-wide study of how selective constraints and adaptations have driven the evolution of innate immunity genes is missing. Using full-genome sequence variation from the 1000 Genomes Project, we first show that innate immunity genes have globally evolved under stronger purifying selection than the remainder of protein-coding genes. We identify a gene set under the strongest selective constraints, mutations in which are likely to predispose individuals to life-threatening disease, as illustrated by STAT1 and TRAF3. We then evaluate the occurrence of local adaptation and detect 57 high-scoring signals of positive selection at innate immunity genes, variation in which has been associated with susceptibility to common infectious or autoimmune diseases. Furthermore, we show that most adaptations targeting coding variation have occurred in the last 6,000–13,000 years, the period at which populations shifted from hunting and gathering to farming. Finally, we show that innate immunity genes present higher Neandertal introgression than the remainder of the coding genome. Notably, among the genes presenting the highest Neandertal ancestry, we find the TLR6-TLR1-TLR10 cluster, which also contains functional adaptive variation in Europeans. This study identifies highly constrained genes that fulfill essential, non-redundant functions in host survival and reveals others that are more permissive to change—containing variation acquired from archaic hominins or adaptive variants in specific populations—improving our understanding of the relative biological importance of innate immunity pathways in natural conditions. PMID:26748513

Associations between dopamine D4 receptor gene variation with both infidelity and sexual promiscuity.

PubMed

Garcia, Justin R; MacKillop, James; Aller, Edward L; Merriwether, Ann M; Wilson, David Sloan; Lum, J Koji

2010-11-30

Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a "one-night stand") and report a more than 50% increase in instances of sexual infidelity. DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism.

Associations between Dopamine D4 Receptor Gene Variation with Both Infidelity and Sexual Promiscuity

PubMed Central

Garcia, Justin R.; MacKillop, James; Aller, Edward L.; Merriwether, Ann M.; Wilson, David Sloan; Lum, J. Koji

2010-01-01

Background Human sexual behavior is highly variable both within and between populations. While sex-related characteristics and sexual behavior are central to evolutionary theory (sexual selection), little is known about the genetic bases of individual variation in sexual behavior. The variable number tandem repeats (VNTR) polymorphism in exon III of the human dopamine D4 receptor gene (DRD4) has been correlated with an array of behavioral phenotypes and may be predicatively responsible for variation in motivating some sexual behaviors, particularly promiscuity and infidelity. Methodology/Principal Findings We administered an anonymous survey on personal history of sexual behavior and intimate relationships to 181 young adults. We also collected buccal wash samples and genotyped the DRD4 VNTR. Here we show that individuals with at least one 7-repeat allele (7R+) report a greater categorical rate of promiscuous sexual behavior (i.e., having ever had a “one-night stand”) and report a more than 50% increase in instances of sexual infidelity. Conclusions/Significance DRD4 VNTR genotype varies considerably within and among populations and has been subject to relatively recent, local selective pressures. Individual differences in sexual behavior are likely partially mediated by individual genetic variation in genes coding for motivation and reward in the brain. Conceptualizing these findings in terms of r/K selection theory suggests a mechanism for selective pressure for and against the 7R+ genotype that may explain the considerable global allelic variation for this polymorphism. PMID:21152404

The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations

PubMed Central

Scheikl, Daniela; Tellier, Aurélien

2017-01-01

Wild tomatoes are a valuable source of disease resistance germplasm for tomato (Solanum lycopersicum) breeders. Many species are known to possess a certain degree of resistance against certain pathogens; however, evolution of resistance traits is yet poorly understood. For some species, like Solanum chilense, both differences in habitat and within species genetic diversity are very large. Here we aim to investigate the occurrence of spatially heterogeneous coevolutionary pressures between populations of S. chilense. We investigate the phenotypic differences in disease resistance within S. chilense against three common tomato pathogens (Alternaria solani, Phytophthora infestans and a Fusarium sp.) and confirm high degrees of variability in resistance properties between selected populations. Using generalised linear mixed models, we show that disease resistance does not follow the known demographic patterns of the species. Models with up to five available climatic and geographic variables are required to best describe resistance differences, confirming the complexity of factors involved in local resistance variation. We confirm that within S. chilense, resistance properties against various pathogens show a mosaic pattern and do not follow environmental patterns, indicating the strength of local pathogen pressures. Our study can form the basis for further investigations of the genetic traits involved. PMID:28133579

The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations.

PubMed

Stam, Remco; Scheikl, Daniela; Tellier, Aurélien

2017-01-01

Wild tomatoes are a valuable source of disease resistance germplasm for tomato ( Solanum lycopersicum ) breeders. Many species are known to possess a certain degree of resistance against certain pathogens; however, evolution of resistance traits is yet poorly understood. For some species, like Solanum chilense , both differences in habitat and within species genetic diversity are very large. Here we aim to investigate the occurrence of spatially heterogeneous coevolutionary pressures between populations of S. chilense . We investigate the phenotypic differences in disease resistance within S. chilense against three common tomato pathogens ( Alternaria solani , Phytophthora infestans and a Fusarium sp .) and confirm high degrees of variability in resistance properties between selected populations. Using generalised linear mixed models, we show that disease resistance does not follow the known demographic patterns of the species. Models with up to five available climatic and geographic variables are required to best describe resistance differences, confirming the complexity of factors involved in local resistance variation. We confirm that within S. chilense , resistance properties against various pathogens show a mosaic pattern and do not follow environmental patterns, indicating the strength of local pathogen pressures. Our study can form the basis for further investigations of the genetic traits involved.

Assessment of the pseudo-tracking approach for the calculation of material acceleration and pressure fields from time-resolved PIV: part II. Spatio-temporal filtering

NASA Astrophysics Data System (ADS)

van Gent, P. L.; Schrijer, F. F. J.; van Oudheusden, B. W.

2018-04-01

The present study characterises the spatio-temporal filtering associated with pseudo-tracking. A combined theoretical and numerical assessment is performed that uses the relatively simple flow case of a two-dimensional Taylor vortex as analytical test case. An additional experimental assessment considers the more complex flow of a low-speed axisymmetric base flow, for which time-resolved tomographic PIV measurements and microphone measurements were obtained. The results of these assessments show how filtering along Lagrangian tracks leads to amplitude modulation of flow structures. A cut-off track length and spatial resolution are specified to support future applications of the pseudo-tracking approach. The experimental results show a fair agreement between PIV and microphone pressure data in terms of fluctuation levels and pressure frequency spectra. The coherence and correlation between microphone and PIV pressure measurements were found to be substantial and almost independent of the track length, indicating that the low-frequency behaviour of the flow could be reproduced regardless of the track length. It is suggested that a spectral analysis can be used inform the selection of a suitable track length and to estimate the local error margin of reconstructed pressure values.

Local Pressure Application Effects on Discomfort, Temperature, and Limb Oxygenation.

PubMed

Games, Kenneth E; Lakin, Joni M; Quindry, John C; Weimar, Wendi H; Sefton, JoEllen M

2016-08-01

Despite significant investment into the development and improvement of military helicopter seat systems, military aviators continue to report seat system related pain and discomfort during prolonged missions. Using a factorial repeated measures design, 15 healthy subjects completed the study, in which focal pressure was applied to two locations on the sitting surfaces of the body (ischial tuberosity and middle of the posterior thigh). Pressure was applied using a purpose-built pressure application system allowing subjects to sit in a position mimicking the sitting position in the UH-60 Black Hawk helicopter. The researchers measured pain using the Category Partitioning Scale and McGill Pain Questionnaire and vascular function using dynamic infrared thermography in the lower leg and pulse oximetry at the great toe. Data were collected before and during a 10-min application of focal pressure applied to either the ischial tuberosity or middle of the posterior thigh and at two different pressure magnitudes (36 or 44 kPa). We found that during a 10-min pressure application, superficial skin temperature increased by 0.61°C, suggesting a decreased venous return during pressure application. We found that lower extremity blood oxygenation remained unchanged during pressure application. Subjects' reported pain increased during pressure application and was greater with 44 kPa of application compared to 36 kPa. These results support the hypothesis that locally high pressure creates symptoms of discomfort and paresthesia. Research examining the effects of local pressure application on physiological and neurological function is needed. Games KE, Lakin JM, Quindry JC, Weimar WH, Sefton JM. Local pressure application effects on discomfort, temperature, and limb oxygenation. Aerosp Med Hum Perform. 2016; 87(8):697-703.

Pop tests of storable biopropellant liquid apogee engine

NASA Astrophysics Data System (ADS)

Kuroda, Yukio; Tadano, Makoto; Sato, Masahiro; Kusaka, Kazuo; Kobayashi, Hideyuki; Iihara, Sigeyasu; Ban, Hiroyuki

1994-10-01

A pressure-fed, blowdown, hydrazine/NTO apogee propulsion system had been selected for the ETS-6. One of the problems encountered during the development of the engine was the occurrence of pops (popping) at the higher operating chamber pressures. Pops are irregular high amplitude pressure pulses. It is generally agreed that pops is a liquid spray/gas two-phase explosion triggered by a local explosion near the jet impingement region. The effects of operating parameters on pops observed in the development tests of the apogee engine for the ETS-6 were inconsistent with those reported earlier for single impingement injectors; pops with the apogee engine injectors was more likely to occur at higher chamber pressures, higher injection velocities, and higher propellant temperatures. Pops data were correlated fairly well in chamber pressures (bar-P(sub c)) vs. fuel Reynolds number (R(sub ef)) plane. However, the range of operating parameters for the above correlation were very narrow since they were obtained during injector screening tests for a particular application to the apogee engine. It was also felt that the above correlation was too simplistic to capture any effect of design parameters of multi-element injectors. In the present study, the demarcation between pops and the pops-free region was determined in broader operating ranges and design parameters. The range of bar-P(sub c) and R(sub ef) was extended by exchanging graphite nozzle throat inserts with different throat diameters. The injectors were carefully selected to obtain effects, if any, of (1) film cooling fraction, (2) secondary mixing, and (3) number of elements and/or fuel orifice diameters. It was found that there was a threshold fuel Reynolds number below which no pops were observed at any chamber pressures and that the pops region curve in the bar-P(sub c)-R(sub ef) plane had two branches: upper branches and lower branches.

Essential oil yield and composition reflect browsing damage of junipers.

PubMed

Markó, Gábor; Gyuricza, Veronika; Bernáth, Jeno; Altbacker, Vilmos

2008-12-01

The impact of browsing on vegetation depends on the relative density and species composition of browsers. Herbivore density and plant damage can be either site-specific or change seasonally and spatially. For juniper (Juniperus communis) forests of a sand dune region in Hungary, it has been assumed that plant damage investigated at different temporal and spatial scales would reflect selective herbivory. The level of juniper damage was tested for a possible correlation with the concentration of plant secondary metabolites (PSMs) in plants and seasonal changes in browsing pressure. Heavily browsed and nonbrowsed junipers were also assumed to differ in their chemical composition, and the spatial distribution of browsing damage within each forest was analyzed to reveal the main browser. Long-term differences in local browsing pressure were also expected and would be reflected in site-specific age distributions of distant juniper populations. The concentrations of PSMs (essential oils) varied significantly among junipers and seasons. Heavily browsed shrubs contained the lowest oil yield; essential oils were highest in shrubs bearing no damage, indicating that PSMs might contribute to reduce browsing in undamaged shrubs. There was a seasonal fluctuation in the yield of essential oil that was lower in the summer period than in other seasons. Gas chromatography (GC) revealed differences in some essential oil components, suggesting that certain chemicals could have contributed to reduced consumption. The consequential long-term changes were reflected in differences in age distribution between distant juniper forests. These results confirm that both the concentration of PSMs and specific compounds of the essential oil may play a role in selective browsing damage by local herbivores.

Corti's organ physiology-based cochlear model: a microelectronic prosthetic implant

NASA Astrophysics Data System (ADS)

Rios, Francisco; Fernandez-Ramos, Raquel; Romero-Sanchez, Jorge; Martin, Jose Francisco

2003-04-01

Corti"s Organ is an Electro-Mechanical transducer that allows the energy coupling between acoustical stimuli and auditory nerve. Although the structure and funtionality of this organ are complex, state of the art models have been currently developed and tested. Cochlea model presented in this paper is based on the theories of Bekesy and others and concerns on the behaviour of auditory system on frequency-place domain and mechanisms of lateral inhibition. At the same time, present state of technology will permit us developing a microsystem that reproduce this phenomena applied to hearing aid prosthesis. Corti"s Organ is composed of more than 20.000 cilia excited by mean of travelling waves. These waves produce relative pressures distributed along the cochlea, exciting an specific number of cilia in a local way. Nonlinear mechanisms of local adaptation to the intensity (external cilia cells) and lateral inhibition (internal cilia cells) allow the selection of very few elements excited. These transmit a very precise intensity and frequency information. These signals are the only ones coupled to the auditory nerve. Distribution of pressure waves matches a quasilogaritmic law due to Cochlea morphology. Microsystem presented in this paper takes Bark"s law as an approximation to this behaviour consisting on grouped arbitrary elements composed of a set of selective coupled exciters (bank of filters according to Patterson"s model).These sets apply the intensity adaptation principles and lateral inhibition. Elements excited during the process generate a bioelectric signal in the same way than cilia cell. A microelectronic solution is presented for the development of an implantable prosthesis device.

Monitoring atmospheric pollutants with a heterodyne radiometer transmitter-receiver

NASA Technical Reports Server (NTRS)

Menzies, R. T. (Inventor)

1973-01-01

The presence of selected atmospheric pollutants can be determined by transmitting an infrared beam of proper wavelength through the atmosphere, and detecting the reflections of the transmitted beam with a heterodyne radiometer transmitter-receiver using part of the laser beam as a local oscillator. The particular pollutant and its absorption line strength to be measured are selected by the laser beam wave length. When the round-trip path for the light is known or measured, concentration can be determined. Since pressure (altitude) will affect the shape of the molecular absorption line of a pollutant, tuning the laser through a range of frequencies, which includes a part of the absorption line of the pollutant of interest, yields pollutant altitude data from which the altitude and altitude profile is determined.

Evaluation of cooling performance of impinging jet array over various dimpled surfaces

NASA Astrophysics Data System (ADS)

Kim, Sun-Min; Kim, Kwang-Yong

2016-04-01

Various configurations of an impinging jet-dimple array cooling system were evaluated in terms of their heat transfer and pressure drop performances. The steady incompressible laminar flow and heat transfer in the cooling system were analyzed using three-dimensional Navier-Stokes equations. The obtained numerical results were validated by a comparison with experimental data for the local Nusselt number distribution. The area-averaged Nusselt number on the projected area and the pressure drop through the system were selected as the performance parameters. Among the four tested configurations—inline concave, staggered concave, inline convex, and staggered convex—the staggered convex impinging jet-dimple array showed the best heat transfer performance whereas the staggered-concave configuration showed the lowest pressure drop. A parametric study with two geometric variables, i.e., the height of dimple and the diameter of dimple, was also conducted for the staggered-convex impinging jet-dimple array. As a result, the best heat transfer and pressure drop performances were achieved when the ratio of the height of dimple to the diameter of jet was 0.8. And, the increase in the ratio of the diameter of dimple to the diameter of jet yielded monotonous increase in the heat transfer performance.

Effect of marihuana on intraocular and blood pressure in glaucoma.

PubMed

Merritt, J C; Crawford, W J; Alexander, P C; Anduze, A L; Gelbart, S S

1980-03-01

Marihuana inhalation was accompanied by increased heart rate and decreased intraocular and blood pressure in 18 subjects with heterogenous glaucomas. The hypotensive effects appeared in 60 to 90 minutes as the decrease in intraocular pressure (IOP) appeared to follow the decrease in blood pressure. In addition to any local effect, the mechanism of lowered to any local effect, the mechanism of lowered IOP may also involve the decreased pressure perfusing the ciliary body vasculature as a result of the peripheral vasodilatory properties of marihuana. Postural hypotension, tachycardia, palpitations, and alterations in mental status occurred with such frequency as to mitigate against the routine used in the general glaucoma population. Our data indicate that further research should be directed to local means of delivering the ocular hypotensive cannabinoid to the glaucomatous eye.

Assessing complexity of skin blood flow oscillations in response to locally applied heating and pressure in rats: Implications for pressure ulcer risk

NASA Astrophysics Data System (ADS)

Liao, Fuyuan; O'Brien, William D.; Jan, Yih-Kuen

2013-10-01

The objective of this study was to investigate the effects of local heating on the complexity of skin blood flow oscillations (BFO) under prolonged surface pressure in rats. Eleven Sprague-Dawley rats were studied: 7 rats underwent surface pressure with local heating (△t=10 °C) and 4 rats underwent pressure without heating. A pressure of 700 mmHg was applied to the right trochanter area of rats for 3 h. Skin blood flow was measured using laser Doppler flowmetry. The loading period was divided into nonoverlapping 30 min epochs. For each epoch, multifractal detrended fluctuation analysis (MDFA) was utilized to compute DFA coefficients and complexity of endothelial related metabolic, neurogenic, and myogenic frequencies of BFO. The results showed that under surface pressure, local heating led to a significant decrease in DFA coefficients of myogenic frequency during the initial epoch of loading period, a sustained decrease in complexity of myogenic frequency, and a significantly higher degree of complexity of metabolic frequency during the later phase of loading period. Surrogate tests showed that the reduction in complexity of myogenic frequency was associated with a loss of nonlinearity whereas increased complexity of metabolic frequency was associated with enhanced nonlinearity. Our results indicate that increased metabolic activity and decreased myogenic response due to local heating manifest themselves not only in magnitudes of metabolic and myogenic frequencies but also in their structural complexity. This study demonstrates the feasibility of using complexity analysis of BFO to monitor the ischemic status of weight-bearing skin and risk of pressure ulcers.

Simulating Air-Entrapment in Low Permeability Mudrocks using a Macroscopic Invasion Percolation Model

NASA Astrophysics Data System (ADS)

Singh, A.; Holt, R. M.; Ramarao, B.; Clemo, T.

2011-12-01

Three radioactive waste disposal landfills at the Waste Control Specialists (WCS) facility in Andrews County, Texas are constructed below grade, within the low-permeability Dockum Group mudrocks (Cooper Canyon Formation) of Triassic age. Recent site investigations at the WCS disposal facilities indicate the presence of a trapped and compressed gas phase in the mudrocks. The Dockum is a low-permeability medium with vertical and horizontal effective hydraulic conductivities of 1.2E-9 cm/s and 2.9E-7 cm/s. The upper 300+ feet of the Dockum is in the unsaturated zone, with an average saturation of 0.87 and average capillary pressure of 2.8 MPa determined from core samples. Air entry pressures on core samples range from from 0.016 to 9.8 MPa, with a mean of 1.0 MPa. Heat dissipation sensors, thermocouple psychrometers, and advanced tensiometers installed in Dockum borehole arrays generally show capillary pressures one order of magnitude less than those measured on core samples. These differences with core data are attributed to the presence of a trapped and compressed gas phase within Dockum materials. In the vicinity of an instrumented borehole, the gas phase pressure equilibrates with atmospheric pressure, lowering the capillary pressure. We have developed a new macroscopic invasion percolation (MIP) model to illustrate the origin of the trapped gas phase in the Dockum rocks. An MIP model differs from invasion percolation (IP) through the definition of macro-scale capillarity. Individual pore throats and necks are not considered. Instead, a near pore-scale block is defined and characterized by a local threshold spanning pressure (a local block-scale breakthrough pressure) that represents the behavior of the subscale network. The model domain is discretized into an array of grid blocks with assigned spanning pressures. An invasion pressure for each block is then determined by the sum of spanning pressure, buoyance forces, and viscous forces. An IP algorithm sorts the invadable blocks, selects the block connected to the growing cluster with the lowest invasion pressure, and invades it. Our new MIP model incorporates several new features, including an efficient three-dimensional clustering algorithm; simultaneous invasion/reinvasion of water and air phases; hysteresis in water and air drainage curves; capability for distributed porosities and drainage parameters; and gas-phase compression and trapping. We apply this model in simulations representing the WCS site and illustrate the origin of the trapped and compressed gas phase in Dockum mudrocks.

Association between general and abdominal obesity with high blood pressure: difference between genders.

PubMed

Silva, Alison O; Silva, Micaelly V; Pereira, Lisley K N; Feitosa, Wallacy M N; Ritti-Dias, Raphael M; Diniz, Paula R B; Oliveira, Luciano M F T

2016-01-01

To assess the association between general and abdominal obesity with high blood pressure in adolescents of both genders from the public school system. This was an epidemiological, descriptive, exploratory study, with a quantitative approach and local scope whose sample consisted of 481 high school students (aged 14-19), selected by using a random cluster sampling strategy. Blood pressure was measured through the use of automated monitor and was considered high when the pressure values were at or above the 95th percentile. The analyses were performed using the chi-squared test and binary logistic regression. The prevalence of high blood pressure was 6.4%, and it was higher among boys (9.0% vs. 4.7%, p<0.05). There was no significant difference between general (p=0.903) and abdominal obesity (p=0.157) when genders were compared. After adjusting for age, high blood pressure was associated with general (OR=6.4; p<0.001) and abdominal obesity (OR=7.0; p<0.001) only among boys, when comparing the fourth quartile with the first quartile of body mass index (≤ 18.6 kg/m(2)vs. ≥ 23.5 kg/m(2)) and waist circumference (≤ 69 cm vs. ≥ 80.1cm). It was observed that general and abdominal obesity are associated with high blood pressure only in boys, regardless of age. Copyright © 2015 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

Impacts of coronary artery eccentricity on macro-recirculation and pressure drops using computational fluid dynamics

NASA Astrophysics Data System (ADS)

Poon, Eric; Thondapu, Vikas; Barlis, Peter; Ooi, Andrew

2017-11-01

Coronary artery disease remains a major cause of mortality in developed countries, and is most often due to a localized flow-limiting stenosis, or narrowing, of coronary arteries. Patients often undergo invasive procedures such as X-ray angiography and fractional flow reserve to diagnose flow-limiting lesions. Even though such diagnostic techniques are well-developed, the effects of diseased coronary segments on local flow are still poorly understood. Therefore, this study investigated the effect of irregular geometries of diseased coronary segments on the macro-recirculation and local pressure minimum regions. We employed an idealized coronary artery model with a diameter of stenosis of 75%. By systematically adjusting the eccentricity and the asymmetry of the coronary stenosis, we uncovered an increase in macro-recirculation size. Most importantly, the presence of this macro-recirculation signifies a local pressure minimum (identified by λ2 vortex identification method). This local pressure minimum has a profound effect on the pressure drops in both longitudinal and planar directions, which has implications for diagnosis and treatment of coronary artery disease. Supported by Australian Research Council LP150100233 and National Computational Infrastructure m45.

Selective pressures in the human bony pelvis: Decoupling sexual dimorphism in the anterior and posterior spaces.

PubMed

Brown, Kirsten M

2015-07-01

Sexual dimorphism in the human bony pelvis is commonly assumed to be related to the intensity of obstetrical selective pressures. With intense obstetrical selective pressures, there should be greater shape dimorphism; with minimal obstetrical selective pressures, there should be reduced shape dimorphism. This pattern is seen in the nondimorphic anterior spaces and highly dimorphic posterior spaces. Decoupling sexual dimorphism in these spaces may in turn be related to the differential influence of other selective pressures, such as biomechanical ones. The relationship between sexual dimorphism and selective pressures in the human pelvis was examined using five skeletal samples (total female n = 101; male n = 103). Pelvic shape was quantified by collecting landmark coordinate data on articulated pelves. Euclidean distance matrix analysis was used to extract the distances that defined the anterior and posterior pelvic spaces. Sex and body mass were used as proxies for obstetrical and biomechanical selective pressures, respectively. MANCOVA analyses demonstrate significant effects of sex and body mass on distances in both the anterior and the posterior spaces. A comparison of the relative contribution of shape variance attributed to each of these factors suggests that the posterior space is more influenced by sex, and obstetrics by proxy, whereas the anterior space is more influenced by body mass, and biomechanics by proxy. Although the overall shape of the pelvis has been influenced by obstetrical and biomechanical selective pressures, there is a differential response within the pelvis to these factors. These results provide new insight into the ongoing debate on the obstetrical dilemma hypothesis. © 2015 Wiley Periodicals, Inc.

Radial and local time structure of the Saturnian ring current, revealed by Cassini

NASA Astrophysics Data System (ADS)

Sergis, N.; Jackman, C. M.; Thomsen, M. F.; Krimigis, S. M.; Mitchell, D. G.; Hamilton, D. C.; Dougherty, M. K.; Krupp, N.; Wilson, R. J.

2017-02-01

We analyze particle and magnetic field data obtained between July 2004 and December 2013 in the equatorial magnetosphere of Saturn, by the Cassini spacecraft. The radial and local time distribution of the total (thermal and suprathermal) particle pressure and total plasma beta (ratio of particle to magnetic pressure) over radial distances from 5 to 16 Saturn radii (RS = 60,258 km) is presented. The average azimuthal current density Jϕ and its separate components (inertial, pressure gradient, and anisotropy) are computed as a function of radial distance and local time and presented as equatorial maps. We explore the relative contribution of different physical mechanisms that drive the ring current at Saturn. Results show that (a) the particle pressure is controlled by thermal plasma inside of 8 RS and by the hot ions beyond 12 RS, exhibiting strong local time asymmetry with higher pressures measured at the dusk and night sectors; (b) the plasma beta increases with radial distance and remains >1 beyond 8-10 RS for all local times; (c) the ring current is asymmetric in local time and forms a maximum region between 7 and 13 RS, with values up to 100-115 pA/m2; and (d) the ring current is inertial everywhere inside of 7 RS, exhibits a mixed nature between 7 and 11 RS and is pressure gradient driven beyond 11 RS, with the exception of the noon sector where the mixed nature persists. In the dawn sector, it appears strongly pressure gradient driven for a wider range of radial distance, consistent with fast return flow of hot, tenuous magnetospheric plasma following tail reconnection.

Barriers to management of cardiovascular risk in a low-resource setting using hypertension as an entry point.

PubMed

Mendis, Shanthi; Abegunde, Dele; Oladapo, Olulola; Celletti, Francesca; Nordet, Porfirio

2004-01-01

Assess capacity of health-care facilities in a low-resource setting to implement the absolute risk approach for assessment of cardiovascular risk in hypertensive patients and effective management of hypertension. A descriptive cross-sectional study in Egbeda and Oluyole local government areas of Oyo State in Nigeria in 56 randomly selected primary- (n = 42) and secondary-level (n = 2) health-care and private health-care (n = 12) facilities. One thousand consecutive, known hypertensives attending the selected facilities for follow-up, and health-care providers working in the above randomly selected facilities, were interviewed. About two-thirds of hypertensives utilized primary-care centers both for diagnosis and for follow-up. Laboratory and other investigations to exclude secondary hypertension or to assess target organ damage were not available in the majority of facilities, particularly in primary care. A considerable knowledge and awareness gap related to hypertension and its complications was found, both among patients and health-care providers. Blood pressure control rates were poor (28% with systolic blood pressure (SBP) < 140 mmHg and diastolic blood pressure (DBP) < 90 mmHg] and drug prescription patterns were not evidence based and cost effective. The majority of patients (73%) in this low socio-economic group (mean monthly income 73 US dollars) had to pay fully, out of their own pocket, for consultations and medications. If the absolute risk approach for assessment of risk and effective management of hypertension is to be implemented in low-resource settings, appropriate policy measures need to be taken to improve the competency of health-care providers, to provide basic laboratory facilities and to develop affordable financing mechanisms.

A pilot study evaluating protein abundance in pressure ulcer fluid from people with and without spinal cord injury

PubMed Central

Edsberg, Laura E.; Wyffels, Jennifer T.; Ogrin, Rajna; Craven, B. Catharine; Houghton, Pamela

2015-01-01

Objective To determine whether the biochemistry of chronic pressure ulcers differs between patients with and without chronic spinal cord injury (SCI) through measurement and comparison of the concentration of wound fluid inflammatory mediators, growth factors, cytokines, acute phase proteins, and proteases. Design Survey. Setting Tertiary spinal cord rehabilitation center and skilled nursing facilities. Participants Twenty-nine subjects with SCI and nine subjects without SCI (>18 years) with at least one chronic pressure ulcer Stage II, III, or IV were enrolled. Outcome measures Total protein and 22 target analyte concentrations including inflammatory mediators, growth factors, cytokines, acute phase proteins, and proteases were quantified in the wound fluid and blood serum samples. Blood samples were tested for complete blood count, albumin, hemoglobin A1c, total iron binding capacity, iron, percent (%) saturation, C-reactive protein, and erythrocyte sedimentation rate. Results Wound fluid concentrations were significantly different between subjects with SCI and subjects without SCI for total protein concentration and nine analytes, MMP-9, S100A12, S100A8, S100A9, FGF2, IL-1b, TIMP-1, TIMP-2, and TGF-b1. Subjects without SCI had higher values for all significantly different analytes measured in wound fluid except FGF2, TGF-b1, and wound fluid total protein. Subject-matched circulating levels of analytes and the standardized local concentration of the same proteins in the wound fluid were weakly or not correlated. Conclusions The biochemical profile of chronic pressure ulcers is different between SCI and non-SCI populations. These differences should be considered when selecting treatment options. Systemic blood serum properties may not represent the local wound environment. PMID:24968005

Low-dose chronic lead exposure increases systolic arterial pressure and vascular reactivity of rat aortas.

PubMed

Silveira, Edna Aparecida; Siman, Fabiana Dayse Magalhães; de Oliveira Faria, Thaís; Vescovi, Marcos Vinícius Altoé; Furieri, Lorena Barros; Lizardo, Juliana Hott Fúcio; Stefanon, Ivanita; Padilha, Alessandra Simão; Vassallo, Dalton Valentim

2014-02-01

Chronic lead exposure induces hypertension affecting endothelial function. We investigated whether low-concentration lead exposure alters blood pressure and vascular reactivity, focusing on the roles of NO, oxidative stress, cyclooxygenase-derived vasoconstrictor prostanoids, and the local angiotensin-renin system. Aortic rings from 3-month-old Wistar rats were treated daily with lead acetate (first dose 4mg/100g, subsequent doses 0.05mg/100g, im) or vehicle for 30 days. Treatment increased lead blood levels (12μg/dl), blood pressure, and aortic ring contractile response to phenylephrine (1nM-100mM). Contractile response after L-NAME administration increased in both groups but was higher after lead treatment. Lead effects on Rmax decreased more after apocynin and superoxide dismutase administration compared to control. Indomethacin reduced phenylephrine response more after lead treatment than in controls. The selective COX-2 inhibitor NS398, thromboxane A2/prostaglandin H2 receptor antagonist SQ 29,548, TXA2 synthase inhibitor furegrelate, EP1 receptor antagonist SC 19220, and ACE inhibitor and AT1 receptor antagonist losartan reduced phenylephrine responses only in vessels from lead-treated rats. Basal and stimulated NO release was reduced and local O2(-) liberation increased in the lead-treated group compared to controls. eNOS, iNOS, and AT1 receptor protein expression increased with lead exposure, but COX-2 protein expression decreased. This is the first demonstration that blood Pb(2+) (12µg/dl) concentrations below the WHO-established values increased systolic blood pressure and vascular phenylephrine reactivity. This effect was associated with reduced NO bioavailability, increased reactive oxygen species production, increased participation of COX-derived contractile prostanoids, and increased renin-angiotensin system activity. © 2013 The Authors. Published by Elsevier Inc. All rights reserved.

Relation of Total and Cardiovascular Death Rates to Climate System, Temperature, Barometric Pressure, and Respiratory Infection.

PubMed

Schwartz, Bryan G; Qualls, Clifford; Kloner, Robert A; Laskey, Warren K

2015-10-15

A distinct seasonal pattern in total and cardiovascular death rates has been reported. The factors contributing to this pattern have not been fully explored. Seven locations (average total population 71,354,000) were selected where data were available including relatively warm, cold, and moderate temperatures. Over the period 2004 to 2009, there were 2,526,123 all-cause deaths, 838,264 circulatory deaths, 255,273 coronary heart disease deaths, and 135,801 ST-elevation myocardial infarction (STEMI) deaths. We used time series and multivariate regression modeling to explore the association between death rates and climatic factors (temperature, dew point, precipitation, barometric pressure), influenza levels, air pollution levels, hours of daylight, and day of week. Average seasonal patterns for all-cause and cardiovascular deaths were very similar across the 7 locations despite differences in climate. After adjusting for multiple covariates and potential confounders, there was a 0.49% increase in all-cause death rate for every 1°C decrease. In general, all-cause, circulatory, coronary heart disease and STEMI death rates increased linearly with decreasing temperatures. The temperature effect varied by location, including temperature's linear slope, cubic fit, positional shift on the temperature axis, and the presence of circulatory death increases in locally hot temperatures. The variable effect of temperature by location suggests that people acclimatize to local temperature cycles. All-cause and circulatory death rates also demonstrated sizable associations with influenza levels, dew point temperature, and barometric pressure. A greater understanding of how climate, temperature, and barometric pressure influence cardiovascular responses would enhance our understanding of circulatory and STEMI deaths. Copyright © 2015 Elsevier Inc. All rights reserved.

Convergent Evolution Associated with Habitat Decouples Phenotype from Phylogeny in a Clade of Lizards

PubMed Central

Edwards, Shelley; Vanhooydonck, Bieke; Herrel, Anthony; Measey, G. John; Tolley, Krystal A.

2012-01-01

Convergent evolution can explain similarity in morphology between species, due to selection on a fitness-enhancing phenotype in response to local environmental conditions. As selective pressures on body morphology may be strong, these have confounded our understanding of the evolutionary relationships between species. Within the speciose African radiation of lacertid lizards (Eremiadini), some species occupy a narrow habitat range (e.g. open habitat, cluttered habitat, strictly rupicolous, or strictly psammophilic), which may exert strong selective pressures on lizard body morphology. Here we show that the overall body plan is unrelated to shared ancestry in the African radiation of Eremiadini, but is instead coupled to habitat use. Comprehensive Bayesian and likelihood phylogenies using multiple representatives from all genera (2 nuclear, 2 mitochondrial markers) show that morphologically convergent species thought to represent sister taxa within the same genus are distantly related evolutionary lineages (Ichnotropis squamulosa and Ichnotropis spp.; Australolacerta rupicola and A. australis). Hierarchical clustering and multivariate analysis of morphological characters suggest that body, and head, width and height (stockiness), all of which are ecologically relevant with respect to movement through habitat, are similar between the genetically distant species. Our data show that convergence in morphology, due to adaptation to similar environments, has confounded the assignment of species leading to misidentification of the taxonomic position of I. squamulosa and the Australolacerta species. PMID:23251601

Changes in bacterial community after application of three different herbicides.

PubMed

Moretto, Jéssica Aparecida Silva; Altarugio, Lucas Miguel; Andrade, Pedro Avelino; Fachin, Ana Lúcia; Andreote, Fernando Dini; Stehling, Eliana Guedes

2017-07-06

The native soil microbiota is very important to maintain the quality of that environment, but with the intensive use of agrochemicals, changes in microbial biomass and formation of large quantities of toxic waste were observed in soil, groundwater and surface water. Thereby, the goal of this study was to evaluate if the selective pressure exerted by the presence of the herbicides atrazine, diuron and 2,4-D changes the bacterial community structure of an agricultural soil, using denaturing gradient gel electrophoresis technique. According to PERMANOVA analysis, a greater effect of the herbicide persistence time in the soil, the effect of the herbicide class and the effect of interaction between these two factors (persistence time and herbicide class) were observed. In conclusion, the results showed that the selective pressure exerted by the presence of these herbicides altered the composition of the local microbiota, being atrazine and diuron that most significantly affected the bacterial community in soil, and the herbicide 2,4-D was the one that less altered the microbial community and that bacterial community was reestablished first. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Impact of selected parameters on the development of boiling and flow resistance in the minichannel

NASA Astrophysics Data System (ADS)

Piasecka, Magdalena; Ziętala, Kinga

2015-05-01

The paper presents results of flow boiling in a rectangular minichannel 1 mm deep, 40 mm wide and 360 mm long. The heating element for FC-72 flowing in the minichannel was the thin alloy foil designated as Haynes-230. There was a microstructure on the side of the foil which comes into contact with fluid in the channel. Two types of microstructured heating surfaces: one with micro-recesses distributed evenly and another with mini-recesses distributed unevenly were used. The paper compares the impact of the microstructured heating surface and minichannel positions on the development of boiling and two phase flow pressure drop. The local heat transfer coefficients and flow resistance obtained in experiment using three positions of the minichannel, e.g.: 0°, 90° and 180° were analyzed. The study of the selected thermal and flow parameters (mass flux density and inlet pressure), geometric parameters and type of cooling liquid on the boiling heat transfer was also conducted. The most important factor turned out to be channel orientation. Application of the enhanced heating surface caused the increase of the heat transfer coefficient from several to several tens per cent, in relation to the plain surface.

Implications of Operational Pressure on CSSE PGS Design

NASA Technical Reports Server (NTRS)

Lee, Ryan

2008-01-01

The Constellation Spacesuit Element (CSSE) was required to support crew survival (CS); launch, entry, and abort (LEA) scenarios; zero gravity (0-g) extravehicular activity (EVA) (both unscheduled and contingency); and planetary EVA. Operation of the CSSE in all of these capacities required a pressure garment subsystem (PGS) that would operate efficiently through various pressure profiles. The PGS team initiated a study to determine the appropriate operational pressure profile of the CSSE and how this selection would affect the design of the CSSE PGS. This study included an extensive review of historical PGS operational pressure selection and the operational effects of those pressures, the presentation of four possible pressure paradigm options for use by the CSSE, the risks and design impacts of these options, and the down-selected pressure option.

Primordial Evolution in the Finitary Process Soup

NASA Astrophysics Data System (ADS)

Görnerup, Olof; Crutchfield, James P.

A general and basic model of primordial evolution—a soup of reacting finitary and discrete processes—is employed to identify and analyze fundamental mechanisms that generate and maintain complex structures in prebiotic systems. The processes—ɛ-machines as defined in computational mechanics—and their interaction networks both provide well defined notions of structure. This enables us to quantitatively demonstrate hierarchical self-organization in the soup in terms of complexity. We found that replicating processes evolve the strategy of successively building higher levels of organization by autocatalysis. Moreover, this is facilitated by local components that have low structural complexity, but high generality. In effect, the finitary process soup spontaneously evolves a selection pressure that favors such components. In light of the finitary process soup's generality, these results suggest a fundamental law of hierarchical systems: global complexity requires local simplicity.

Remotely actuated localized pressure and heat apparatus and method of use

NASA Technical Reports Server (NTRS)

Merret, John B. (Inventor); Taylor, DeVor R. (Inventor); Wheeler, Mark M. (Inventor); Gale, Dan R. (Inventor)

2004-01-01

Apparatus and method for the use of a remotely actuated localized pressure and heat apparatus for the consolidation and curing of fiber elements in, structures. The apparatus includes members for clamping the desired portion of the fiber elements to be joined, pressure members and/or heat members. The method is directed to the application and use of the apparatus.

Cardiovascular adaptation to spaceflight

NASA Technical Reports Server (NTRS)

Hargens, A. R.; Watenpaugh, D. E.

1996-01-01

This article reviews recent flight and ground-based studies of cardiovascular adaptation to spaceflight. Prominent features of microgravity exposure include loss of gravitational pressures, relatively low venous pressures, headward fluid shifts, plasma volume loss, and postflight orthostatic intolerance and reduced exercise capacity. Many of these short-term responses to microgravity extend themselves during long-duration microgravity exposure and may be explained by altered pressures (blood and tissue) and fluid balance in local tissues nourished by the cardiovascular system. In this regard, it is particularly noteworthy that tissues of the lower body (e.g., foot) are well adapted to local hypertension on Earth, whereas tissues of the upper body (e.g., head) are not as well adapted to increase in local blood pressure. For these and other reasons, countermeasures for long-duration flight should include reestablishment of higher, Earth-like blood pressures in the lower body.

NMR evidence for static local nematicity and its cooperative interplay with low-energy magnetic fluctuations in FeSe under pressure

DOE PAGES

Wiecki, P.; Nandi, M.; Bohmer, Anna; ...

2017-11-13

Here, we present 77Se -NMR measurements on single-crystalline FeSe under pressures up to 2 GPa. Based on the observation of the splitting and broadening of the NMR spectrum due to structural twin domains, we discovered that static, local nematic ordering exists well above the bulk nematic ordering temperature, T s. The static, local nematic order and the low-energy stripe-type antiferromagnetic spin fluctuations, as revealed by NMR spin-lattice relaxation rate measurements, are both insensitive to pressure application. Our NMR results provide clear evidence for the microscopic cooperation between magnetism and local nematicity in FeSe.

NMR evidence for static local nematicity and its cooperative interplay with low-energy magnetic fluctuations in FeSe under pressure

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

Wiecki, P.; Nandi, M.; Bohmer, Anna

Here, we present 77Se -NMR measurements on single-crystalline FeSe under pressures up to 2 GPa. Based on the observation of the splitting and broadening of the NMR spectrum due to structural twin domains, we discovered that static, local nematic ordering exists well above the bulk nematic ordering temperature, T s. The static, local nematic order and the low-energy stripe-type antiferromagnetic spin fluctuations, as revealed by NMR spin-lattice relaxation rate measurements, are both insensitive to pressure application. Our NMR results provide clear evidence for the microscopic cooperation between magnetism and local nematicity in FeSe.

Accounting for local adaptation in ectomycorrhizas: a call to track geographical origin of plants, fungi, and soils in experiments.

PubMed

Rúa, Megan A; Lamit, Louis J; Gehring, Catherine; Antunes, Pedro M; Hoeksema, Jason D; Zabinski, Cathy; Karst, Justine; Burns, Cole; Woods, Michaela J

2018-02-01

Local adaptation, the differential success of genotypes in their native versus foreign environments, can influence ecological and evolutionary processes, yet its importance is difficult to estimate because it has not been widely studied, particularly in the context of interspecific interactions. Interactions between ectomycorrhizal (EM) fungi and their host plants could serve as model system for investigations of local adaptation because they are widespread and affect plant responses to both biotic and abiotic selection pressures. Furthermore, because EM fungi cycle nutrients and mediate energy flow into food webs, their local adaptation may be critical in sustaining ecological function. Despite their ecological importance and an extensive literature on their relationships with plants, the vast majority of experiments on EM symbioses fail to report critical information needed to assess local adaptation: the geographic origin of the plant, fungal inocula, and soil substrate used in the experiment. These omissions limit the utility of such studies and restrict our understanding of EM ecology and evolution. Here, we illustrate the potential importance of local adaptation in EM relationships and call for consistent reporting of the geographic origin of plant, soil, and fungi as an important step towards a better understanding of the ecology and evolution of EM symbioses.

Spatial Variation of Pressure in the Lyophilization Product Chamber Part 2: Experimental Measurements and Implications for Scale-up and Batch Uniformity.

PubMed

Sane, Pooja; Varma, Nikhil; Ganguly, Arnab; Pikal, Michael; Alexeenko, Alina; Bogner, Robin H

2017-02-01

Product temperature during the primary drying step of freeze-drying is controlled by a set point chamber pressure and shelf temperature. However, recent computational modeling suggests a possible variation in local chamber pressure. The current work presents an experimental verification of the local chamber pressure gradients in a lab-scale freeze-dryer. Pressure differences between the center and the edges of a lab-scale freeze-dryer shelf were measured as a function of sublimation flux and clearance between the sublimation front and the shelf above. A modest 3-mTorr difference in pressure was observed as the sublimation flux was doubled from 0.5 to 1.0 kg·h -1 ·m -2 at a clearance of 2.6 cm. Further, at a constant sublimation flux of 1.0 kg·h -1 ·m -2 , an 8-fold increase in the pressure drop was observed across the shelf as the clearance was decreased from 4 to 1.6 cm. Scale-up of the pressure variation from lab- to a manufacturing-scale freeze-dryer predicted an increased uniformity in drying rates across the batch for two frequently used pharmaceutical excipients (mannitol and sucrose at 5% w/w). However, at an atypical condition of shelf temperature of +10°C and chamber pressure of 50 mTorr, the product temperature in the center vials was calculated to be a degree higher than the edge vial for a low resistance product, thus reversing the typical edge and center vial behavior. Thus, the effect of local pressure variation is more significant at the manufacturing-scale than at a lab-scale and accounting for the contribution of variations in the local chamber pressures can improve success in scale-up.

Grafting with Cryopreserved Amniotic Membrane versus Conservative Wound Care in Treatment of Pressure Ulcers: A Randomized Clinical Trial

PubMed Central

Dehghani, Mehdi; Azarpira, Negar; Mohammad Karimi, Vahid; Mossayebi, Hamid; Esfandiari, Elaheh

2017-01-01

Objective: To compare the healing process of pressure ulcers treated with cryopreserved human amniotic membrane allograft and routine pressure ulcer care in our hospital. Methods: From January 2012 to December 2013, in a prospective randomized clinical trial (IRCT201612041335N2), 24 patients with second and third stage of pressure ulcers were enrolled in this study. All patients needed split-thickness skin grafts for pressure ulcer-wound coverage. Selected patients had symmetric ulcers on both upper and lower extremities. The patients were randomly divided into two groups: amnion and control. In the amnion group, the ulcer was covered with cryopreserved amniotic membrane and in the control group it was treated with local Dilantin powder application. The duration and success rate of complete healing was compared between the two groups. Results: The study group was composed of 24 pressure ulcers in 24 patients (19 males and 5 females) with a mean age of 44±12.70 years. The demographic characteristics, ulcer area, and underlying diseases were similar in both groups. The early sign of response, such as decrease in wound discharge, was detected 12-14 days after biological dressing. Complete pressure ulcer healing occurred only in the amnion group (p< 0.001). Partial healing was significantly higher in the amnion group (p< 0.03). Healing time in this group was faster than that the control group (20 days versus 54 days). No major complication was recorded with amniotic membrane dressing Conclusion: Cryopreserved amniotic membrane is an effective biologic dressing that promotes re-epithelialization in pressure ulcers PMID:29177171

The National Expert Standard Pressure Ulcer Prevention in Nursing and pressure ulcer prevalence in German health care facilities: a multilevel analysis.

PubMed

Wilborn, Doris; Grittner, Ulrike; Dassen, Theo; Kottner, Jan

2010-12-01

The objective of this study was to describe the relationship between the German National Expert Standard Pressure Ulcer Prevention and the pressure ulcer prevalence in German nursing homes and hospitals. The patient outcome pressure ulcer does not only depend on individual characteristics of patients, but also on institutional factors. In Germany, National Expert Standards are evidence-based instruments that build the basis of continuing improvement in health care quality. It is expected that after having implemented the National Expert Standard Pressure Ulcer Prevention, the number of pressure ulcers should decrease in health care institutions. The analysed data were obtained from two cross-sectional studies from 2004-2005. A multilevel analysis was performed to show the impact of the National Expert Standard Pressure Ulcer Prevention on pressure ulcer prevalence. A total of 41.5% of hospitals and 38.8% of the nursing homes claimed to use the National Expert Standard in the process of developing their local protocols. The overall pressure ulcer prevalence grade 2-4 was 4.7%. Adjusted for hospital departments, survey year and individual characteristics, there was no significant difference in the prevalence of pressure ulcers between institutions that refer to the National Expert Standard or those referring to other sources in developing their local protocols (OR=1.14, 95% CI=0.90-1.44). There was no empirical evidence demonstrating that local protocols of pressure ulcer prevention based on the National Expert Standard were superior to local protocols which refer other sources of knowledge with regard to the pressure ulcer prevalence. The use of the National Expert Standard Pressure Ulcer Prevention can neither be recommended nor be refused. The recent definition of implementation of Expert Standards should be mandatory for all health care institutions which introduce Expert Standards. © 2010 Blackwell Publishing Ltd.

Signatures of positive selection in African Butana and Kenana dairy zebu cattle.

PubMed

Bahbahani, Hussain; Salim, Bashir; Almathen, Faisal; Al Enezi, Fahad; Mwacharo, Joram M; Hanotte, Olivier

2018-01-01

Butana and Kenana are two types of zebu cattle found in Sudan. They are unique amongst African indigenous zebu cattle because of their high milk production. Aiming to understand their genome structure, we genotyped 25 individuals from each breed using the Illumina BovineHD Genotyping BeadChip. Genetic structure analysis shows that both breeds have an admixed genome composed of an even proportion of indicine (0.75 ± 0.03 in Butana, 0.76 ± 0.006 in Kenana) and taurine (0.23 ± 0.009 in Butana, 0.24 ± 0.006 in Kenana) ancestries. We also observe a proportion of 0.02 to 0.12 of European taurine ancestry in ten individuals of Butana that were sampled from cattle herds in Tamboul area suggesting local crossbreeding with exotic breeds. Signatures of selection analyses (iHS and Rsb) reveal 87 and 61 candidate positive selection regions in Butana and Kenana, respectively. These regions span genes and quantitative trait loci (QTL) associated with biological pathways that are important for adaptation to marginal environments (e.g., immunity, reproduction and heat tolerance). Trypanotolerance QTL are intersecting candidate regions in Kenana cattle indicating selection pressure acting on them, which might be associated with an unexplored level of trypanotolerance in this cattle breed. Several dairy traits QTL are overlapping the identified candidate regions in these two zebu cattle breeds. Our findings underline the potential to improve dairy production in the semi-arid pastoral areas of Africa through breeding improvement strategy of indigenous local breeds.

Cancer Liquid Biopsy: Is It Ready for Clinic?

PubMed

Pan, Ying; Ji, John S; Jin, Jason Gang; Kuo, Winston Patrick; Kang, Hongjun

2017-01-01

The management of cancer relies on a combination of imaging and tissue biopsy for diagnosis, monitoring, and molecular classification-based patient stratification to ensure appropriate treatment. Conventional tissue biopsy harvests tumor samples with invasive procedures, which are often difficult for patients with advanced disease. Given the well-recognized intratumor genetic heterogeneity [1], the biopsy of small tumor fragments does not necessarily represent all the genetic aberrations in the tumor, but sampling the entire tumor in each patient is not realistic. Moreover, tumors evolve all the time from local to advanced disease and by adapting to selective pressure from treatment.

Highly birefringent suspended-core photonic microcells for refractive-index sensing

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

Wang, Chao; The Hong Kong Polytechnic University Shenzhen Research Institute, Shenzhen 518057; Jin, Wa

2014-08-11

An in-line photonic microcell with a highly birefringent suspended microfiber core is fabricated by locally heating and pressurizing selected air-holes of an endless single mode photonic crystal fiber. The microfiber core has rhombus-like cross-sectional geometry and could achieve a high birefringence of up to 10{sup −2}. The microfiber core is fixed at the center of the microcell by thin struts attached to an outer jacket tube, which protects and isolates the microfiber from environmental contaminations. Highly sensitive and robust refractive index sensors based on such microcells are experimentally demonstrated.

Acoustic Response of Microbubbles Derived from Phase-Change Nanodroplet

NASA Astrophysics Data System (ADS)

Kawabata, Ken-ichi; Asami, Rei; Azuma, Takashi; Umemura, Shin-ichiro

2010-07-01

An in vitro feasibility test for a novel ultrasound therapy using a type of superheated perfluorocarbon droplet, phase-change nanodroplet (PCND), was performed in gel phantoms with the goal of high selectivity and low invasiveness. Measurements of broadband signal emission revealed that a triggering ultrasound pulse (peak negative pressure of 2.4 MPa) reduces the pressure threshold for cavitation induced by a subsequent ultrasound exposure at an order of magnitude from 2.4 to 0.2 MPa. The maximum allowed interval between the two ultrasound exposures for inducing cavitation with 100- and 1,000-cycle triggering ultrasound was about 100 and 500 ms, respectively. The echo signal increases induced by the triggering ultrasound with 100- and 1000-cycles were enhanced and suppressed by the subsequent ultrasound exposure, respectively. This different behavior seemed to be due to the presence of enlarged free bubbles, which should be avoided for the localization of therapeutic effects.

Modes of elastic plates and shells in water driven by modulated radiation pressure of focused ultrasound

NASA Astrophysics Data System (ADS)

Marston, Philip L.; Daniel, Timothy D.; Abawi, Ahmad T.; Kirsteins, Ivars

2015-11-01

The modulated radiation pressure (MRP) of ultrasound has been used for decades to selectively excite low frequency modes associated with surface tension of fluid objects in water. Much less is known about the excitation of low frequency modes of less compliant metallic objects. Here we use MRP of focused ultrasound to excite resonant flexural vibrations of a circular metal plate in water. The source transducer was driven with a double-sideband suppressed carrier voltage as in. The response of the target (detected with a hydrophone) was at twice the modulation frequency and proportional to the square of the drive voltage. Since the radiation pressure of focused beams is spatially localized, mode shapes could be identified by scanning the source along the target while measuring the target's response. Additional measurements were done with an open-ended water-filled copper circular cylindrical shell in which resonant frequencies and mode shapes were also identified. These experiments show how focused ultrasound can be used to identify low-frequency modes of elastic objects without direct contact. Supported by ONR.

Short- and long-term consequences of early developmental conditions: a case study on wild and domesticated zebra finches.

PubMed

Tschirren, B; Rutstein, A N; Postma, E; Mariette, M; Griffith, S C

2009-02-01

Divergent selection pressures among populations can result not only in significant differentiation in morphology, physiology and behaviour, but also in how these traits are related to each other, thereby driving the processes of local adaptation and speciation. In the Australian zebra finch, we investigated whether domesticated stock, bred in captivity over tens of generations, differ in their response to a life-history manipulation, compared to birds taken directly from the wild. In a 'common aviary' experiment, we thereto experimentally manipulated the environmental conditions experienced by nestlings early in life by means of a brood size manipulation, and subsequently assessed its short- and long-term consequences on growth, ornamentation, immune function and reproduction. As expected, we found that early environmental conditions had a marked effect on both short- and long-term morphological and life-history traits in all birds. However, although there were pronounced differences between wild and domesticated birds with respect to the absolute expression of many of these traits, which are indicative of the different selection pressures wild and domesticated birds were exposed to in the recent past, manipulated rearing conditions affected morphology and ornamentation of wild and domesticated finches in a very similar way. This suggests that despite significant differentiation between wild and domesticated birds, selection has not altered the relationships among traits. Thus, life-history strategies and investment trade-offs may be relatively stable and not easily altered by selection. This is a reassuring finding in the light of the widespread use of domesticated birds in studies of life-history evolution and sexual selection, and suggests that adaptive explanations may be legitimate when referring to captive bird studies.

Identification and validation of single nucleotide polymorphisms in growth- and maturation-related candidate genes in sole (Solea solea L.).

PubMed

Diopere, Eveline; Hellemans, Bart; Volckaert, Filip A M; Maes, Gregory E

2013-03-01

Genomic methodologies applied in evolutionary and fisheries research have been of great benefit to understand the marine ecosystem and the management of natural resources. Although single nucleotide polymorphisms (SNPs) are attractive for the study of local adaptation, spatial stock management and traceability, and investigating the effects of fisheries-induced selection, they have rarely been exploited in non-model organisms. This is partly due to difficulties in finding and validating SNPs in species with limited or no genomic resources. Complementary to random genome-scan approaches, a targeted candidate gene approach has the potential to unveil pre-selected functional diversity and provides more in depth information on the action of selection at specific genes. For example genes can be under selective pressure due to climate change and sustained periods of heavy fishing pressure. In this study, we applied a candidate gene approach in sole (Solea solea L.), an important member of the demersal ecosystem. As consumption flatfish it is heavy exploited and has experienced associated life-history changes over the last 60years. To discover novel genetic polymorphisms in or around genes linked to important life history traits in sole, we screened a total of 76 candidate genes related to growth and maturation using a targeted resequencing approach. We identified in total 86 putative SNPs in 22 genes and validated 29 SNPs using a multiplex single-base extension genotyping assay. We found 22 informative SNPs, of which two represent non-synonymous mutations, potentially of functional relevance. These novel markers should be rapidly and broadly applicable in analyses of natural sole populations, as a measure of the evolutionary signature of overfishing and for initiatives on marker assisted selection. Copyright © 2012 Elsevier B.V. All rights reserved.

Development of Dynamic Flow Field Pressure Probes Suitable for Use in Large Scale Supersonic Wind Tunnels

NASA Technical Reports Server (NTRS)

Porro, A. Robert

2000-01-01

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10-by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor staff and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Pressure Probe Designs for Dynamic Pressure Measurements in a Supersonic Flow Field. [conducted in the Glenn Supersonic Wind Tunnel (SWT)

NASA Technical Reports Server (NTRS)

Porro, A. Robert

2001-01-01

A series of dynamic flow field pressure probes were developed for use in large-scale supersonic wind tunnels at NASA Glenn Research Center. These flow field probes include pitot, static, and five-hole conical pressure probes that are capable of capturing fast acting flow field pressure transients that occur on a millisecond time scale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The five-hole conical pressure probes are used primarily to determine local flow angularity, but can also determine local Mach number. These probes were designed, developed, and tested at the NASA Glenn Research Center. They were also used in a NASA Glenn 10- by 10-Foot Supersonic Wind Tunnel (SWT) test program where they successfully acquired flow field pressure data in the vicinity of a propulsion system during an engine compressor stall and inlet unstart transient event. Details of the design, development, and subsequent use of these probes are discussed in this report.

Local plantar pressure relief in therapeutic footwear: design guidelines from finite element models.

PubMed

Erdemir, Ahmet; Saucerman, Jeffrey J; Lemmon, David; Loppnow, Bryan; Turso, Brie; Ulbrecht, Jan S; Cavanagh, Peter Re

2005-09-01

A major goal of therapeutic footwear in patients with pain or those at risk for skin injury is to relieve focal loading under prominent metatarsal heads. One frequent approach is to place plugs of compliant material into the midsole of the shoe. This study investigated 36 plug designs, a combination of three materials, six geometries, and two placements using a two-dimensional (2D) finite element model. Realistic loading conditions were obtained from plantar pressures (PP) recorded during walking in five subjects who wore control midsoles manufactured using Microcell Puff. Measured peak pressures underneath the second metatarsal head were similar to the results of the control model. PP obtained from simulations with the plugs built into a firm midsole were compared to the simulation results of the control midsole. Large plugs (e.g. 40 mm width), made out of Microcell Puff Lite or Plastazote Medium, placed at peak pressure sites, resulted in highest reductions in peak pressures (18-28%). Smaller plugs benefited from tapering when placed at high pressure areas. Case studies were completed on a healthy male subject and a diabetic female patient to address the efficacy of a plug design favored by our simulations (pressure based placement, 40 x 20 mm, Plastazote Medium). Successful reductions of second metatarsal head pressures were observed with a mediolateral load redistribution that was not represented by our model. 2D computer simulations allowed systematic investigation of plug properties without the need for high volume experimentation on human subjects and established basic guidelines for plug selection. In particular, plugs that are placed based on plantar pressure measurements were proven to be more effective when compared to those positioned according to the projection of the bony landmark on the foot-shoe plantar contact area.

Vertical distribution of ozone and the variation of tropopause heights based on ozonesonde and satellite observations. [Contract title: Internal Wave Motion

NASA Technical Reports Server (NTRS)

Hung, R. J.; Liu, J. M.

1986-01-01

The distribution of atmospheric ozone is nonuniform both in space and time. Local ozone concentration vary with altitude, latitude, longitude, and season. Two year ozonesonde data, January 1981 to December 1982, observed at four Canadian stations and 2.5 year backscattered ultraviolet experiment data on the Nimbus-4 satellite, April 1970 to August 1972, observed over five American stations were used to study the relationship between the total ozone, vertical height distribution of the ozone mixing ratio, vertical height distribution of half total ozone, and the local tropopause height. The results show that there is a postive correlation between total ozone in Dobson Units and the tropopause height in terms of atmospheric pressure. This result suggests that local intrusion of the statosphere into the troposphere, or the local decreasing of tropopause height could occur if there is a local increasing of total ozone. A comparison of the vertical height distribution of the ozone mixing ratio, the modified pressure height of half total ozone and the tropopause height shows that the pressure height of an ozone mixing ratio of 0.3 micrograms/g, and the modified pressure height of half total ozone are very well correlated with the tropopause pressure height.

Direct measurements of local bed shear stress in the presence of pressure gradients

NASA Astrophysics Data System (ADS)

Pujara, Nimish; Liu, Philip L.-F.

2014-07-01

This paper describes the development of a shear plate sensor capable of directly measuring the local mean bed shear stress in small-scale and large-scale laboratory flumes. The sensor is capable of measuring bed shear stress in the range 200 Pa with an accuracy up to 1 %. Its size, 43 mm in the flow direction, is designed to be small enough to give spatially local measurements, and its bandwidth, 75 Hz, is high enough to resolve time-varying forcing. Typically, shear plate sensors are restricted to use in zero pressure gradient flows because secondary forces on the edge of the shear plate caused by pressure gradients can introduce large errors. However, by analysis of the pressure distribution at the edges of the shear plate in mild pressure gradients, we introduce a new methodology for correcting for the pressure gradient force. The developed sensor includes pressure tappings to measure the pressure gradient in the flow, and the methodology for correction is applied to obtain accurate measurements of bed shear stress under solitary waves in a small-scale wave flume. The sensor is also validated by measurements in a turbulent flat plate boundary layer in open channel flow.

Local blockage of EMMPRIN impedes pressure ulcers healing in a rat model.

PubMed

Zhao, Xi-Lan; Luo, Xiao; Wang, Ze-Xin; Yang, Guo-Li; Liu, Ji-Zhong; Liu, Ya-Qiong; Li, Ming; Chen, Min; Xia, Yong-Mei; Liu, Jun-Jie; Qiu, Shu-Ping; Gong, Xiao-Qing

2015-01-01

Excessive extracellular matrix degradation caused by the hyperfunction of matrix metalloproteinases (MMPs) has been implicated in the failure of pressure ulcers healing. EMMPRIN, as a widely expressed protein, has emerged as an important regulator of MMP activity. We hypothesize that EMMPRIN affects the process of pressure ulcer healing by modulating MMP activity. In the rat pressure ulcer model, the expression of EMMPRIN in ulcers detected by Western blot was elevated compared with that observed in normal tissue. To investigate the role of EMMPRIN in regulating ulcer healing, specific antibodies against EMMPRIN were used via direct administration on the pressure ulcer. Local blockage of EMMPRIN resulted in a poor ulcer healing process compared with control ulcers, which was the opposite of our expectation. Furthermore, inhibiting EMMPRIN minimally impacted MMP activity. However, the collagen content in the pressure ulcer was reduced in the EMMPRIN treated group. Angiogenesis and the expression of angiogenic factors in pressure ulcers were also reduced by EMMPRIN local blockage. The results in the present study indicate a novel effect of EMMPRIN in the regulation of pressure ulcer healing by controlling the collagen contents and angiogenesis rather than MMPs activity.

Bond-selective imaging of deep tissue through the optical window between 1600 and 1850 nm.

PubMed

Wang, Pu; Wang, Han-Wei; Sturek, Michael; Cheng, Ji-Xin

2012-01-01

We report the employment of an optical window between 1600 nm and 1850 nm for bond-selective deep tissue imaging through harmonic vibrational excitation and acoustic detection of resultant pressure waves. In this window where a local minimum of water absorption resides, we found a 5 times enhancement of photoacoustic signal by first overtone excitation of the methylene group CH(2) at 1730 nm, compared to the second overtone excitation at 1210 nm. The enhancement allows 3D mapping of intramuscular fat with improved contrast and of lipid deposition inside an atherosclerotic artery wall in the presence of blood. Moreover, lipid and protein are differentiated based on the first overtone absorption profiles of CH(2) and methyl group CH(3) in this window. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Abdominal intra-compartment syndrome - a non-hydraulic model of abdominal compartment syndrome due to post-hepatectomy hemorrhage in a man with a localized frozen abdomen due to extensive adhesions: a case report.

PubMed

Bressan, Alexsander K; Kirkpatrick, Andrew W; Ball, Chad G

2016-09-15

Postoperative hemorrhage is a significant cause of morbidity and mortality following liver resection. It typically presents early within the postoperative period, and conservative management is possible in the majority of cases. We present a case of late post-hepatectomy hemorrhage associated with overt abdominal compartment syndrome resulting from a localized functional compartment within the abdomen. A 68-year-old white man was readmitted with sudden onset of upper abdominal pain, vomiting, and hemodynamic instability 8 days after an uneventful hepatic resection for metachronous colon cancer metastasis. A frozen abdomen with adhesions due to complicated previous abdominal surgeries was encountered at the first intervention, but the surgery itself and initial recovery were otherwise unremarkable. Prompt response to fluid resuscitation at admission was followed by a computed tomography of his abdomen that revealed active arterial hemorrhage in the liver resection site and hemoperitoneum (estimated volume <2 L). Selective arteriography successfully identified and embolized a small bleeding branch of his right hepatic artery. He remained hemodynamically stable, but eventually developed overt abdominal compartment syndrome. Surgical exploration confirmed a small volume of ascites and blood clots (1.2 L) under significant pressure in his supramesocolic region, restricted by his frozen lower abdomen, which we evacuated. Dramatic improvement in his ventilatory pressure was immediate. His abdomen was left open and a negative pressure device was placed for temporary abdominal closure. The fascia was formally closed after 48 hours. He was discharged home at postoperative day 6. Intra-abdominal pressure and radiologic findings of intra-abdominal hemorrhage should be carefully interpreted in patients with extensive intra-abdominal adhesions. A high index of suspicion and detailed understanding of abdominal compartment mechanics are paramount for the timely diagnosis of abdominal compartment syndrome in these patients. Clinicians should be aware that abnormal anatomy (such as adhesions) coupled with localized pathophysiology (such as hemorrhage) can create a so-named abdominal intra-compartment syndrome requiring extra vigilance to diagnose.

GWA Mapping of Anthocyanin Accumulation Reveals Balancing Selection of MYB90 in Arabidopsis thaliana

PubMed Central

Bac-Molenaar, Johanna A.; Fradin, Emilie F.; Rienstra, Juriaan A.; Vreugdenhil, Dick; Keurentjes, Joost J. B.

2015-01-01

Induction of anthocyanin accumulation by osmotic stress was assessed in 360 accessions of Arabidopsis thaliana. A wide range of natural variation, with phenotypes ranging from green to completely red/purple rosettes, was observed. A genome wide association (GWA) mapping approach revealed that sequence diversity in a small 15 kb region on chromosome 1 explained 40% of the variation observed. Sequence and expression analyses of alleles of the candidate gene MYB90 identified a causal polymorphism at amino acid (AA) position 210 of this transcription factor of the anthocyanin biosynthesis pathway. This amino acid discriminates the two most frequent alleles of MYB90. Both alleles are present in a substantial part of the population, suggesting balancing selection between these two alleles. Analysis of the geographical origin of the studied accessions suggests that the macro climate is not the driving force behind positive or negative selection for anthocyanin accumulation. An important role for local climatic conditions is, therefore, suggested. This study emphasizes that GWA mapping is a powerful approach to identify alleles that are under balancing selection pressure in nature. PMID:26588092

7 CFR 246.5 - Selection of local agencies.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 7 Agriculture 4 2011-01-01 2011-01-01 false Selection of local agencies. 246.5 Section 246.5... State and Local Agency Eligibility § 246.5 Selection of local agencies. (a) General. This section sets forth the procedures the State agency shall perform in the selection of local agencies and the expansion...

Source-receptor relationships for PM2.5 during typical pollution episodes in the Pearl River Delta city cluster, China

NASA Astrophysics Data System (ADS)

Fan, Q.; Liu, Y.; Hong, Y.; Wang, X.; Chan, P.; Chen, X.; Lai, A.; Wang, M.; Chen, X.

2017-12-01

Located in the Southern China monsoon region, pollution days in Pearl River Delta (PRD) were classified into "Western type", "Central type" or "Eastern type", with a relative percentage of 67%, 24% and 9%, respectively. Using this classification system, three typical pollution events were selected for numerical simulations using the WRF-Chem model. The source sensitivity method for anthropogenic emissions of PM2.5 and its precursors was applied to identify the source-receptor relationships for PM2.5 among 9 cities in PRD. For "Western type" case, the PRD region was under control of a high-pressure system with easterly prevailing winds. The PM2.5 concentrations in the western PRD region were higher than those in the eastern region, with emissions from cities in the eastern PRD region having higher contributions. Within the PRD's urban cluster, PM2.5 in Huizhou, Dongguan and Shenzhen was mainly derived from local emissions, whereas the PM2.5 in the other cities was primarily derived from external transport. For "Eastern type" case, the PRD was influenced by Typhoon Soulik with westerly prevailing winds. Emissions from cities in the western PRD region had the highest impacts on the overall PM2.5 concentration. PM2.5 in Jiangmen and Foshan was primarily derived from local emissions. Regarding "Central type" case, the PRD region was under control of a uniform pressure field with low wind speed. PM2.5 concentrations of each city were primarily caused by local emissions. Overall, wind flows played a significant role in the transport and spatial distribution of PM2.5 across the PRD region. Ideally, local governments would be wise to establish joint prevention and control measures to reduce regional atmospheric pollution, especially for "Western type" pollution.

Intelligent telemetric stent for wireless monitoring of intravascular pressure and its in vivo testing.

PubMed

Chen, Xing; Brox, Daniel; Assadsangabi, Babak; Hsiang, York; Takahata, Kenichi

2014-10-01

This paper reports a sensor-integrated telemetric stent targeted at wireless detection and monitoring of restenosis, a common vascular complication induced by stent implantation. The developed "smart" stent incorporates the design and fabrication approaches that raise the practicality of the device, being tested in an in vivo study that validates its operating principle. The stent is produced to have a gold-coated helical-like structure that serves as a high-performance inductor/antenna and integrated with a novel capacitive pressure sensor chip, all based on medical-grade stainless steel. The stent device forms an inductor-capacitor resonant tank that enables radio-frequency (RF) wireless pressure sensing in an operating frequency range of 30-80 MHz. With an overall length of 20 mm, the device is designed to be compatible with standard balloon catheters and necessary crimping process. The balloon-expanded devices are characterized in saline and blood to determine selective coating of passivation layer, Parylene C, with tailored thicknesses in order to maximize both RF and sensing abilities. In vitro testing of the devices reveals a frequency sensitivity up to 146 ppm/mmHg over a pressure range of 250 mmHg. Tests in pig models show wireless detection of device's resonance and frequency response to variations in local blood pressure, the targeted function of the device.

Deterministic estimate of hypocentral pore fluid pressure of the M5.8 Pawnee, Oklahoma earthquake: Lower pre-injection pressure requires lower resultant pressure for slip

NASA Astrophysics Data System (ADS)

Levandowski, W. B.; Walsh, F. R. R.; Yeck, W.

2016-12-01

Quantifying the increase in pore-fluid pressure necessary to cause slip on specific fault planes can provide actionable information for stakeholders to potentially mitigate hazard. Although the M5.8 Pawnee earthquake occurred on a previously unmapped fault, we can retrospectively estimate the pore-pressure perturbation responsible for this event. We first estimate the normalized local stress tensor by inverting focal mechanisms surrounding the Pawnee Fault. Faults are generally well oriented for slip, with instabilities averaging 96% of maximum. Next, with an estimate of the weight of local overburden we solve for the pore pressure needed at the hypocenters. Specific to the Pawnee fault, we find that hypocentral pressure 43-104% of hydrostatic (accounting for uncertainties in all relevant parameters) would have been sufficient to cause slip. The dominant source of uncertainty is the pressure on the fault prior to fluid injection. Importantly, we find that lower pre-injection pressure requires lower resultant pressure to cause slip, decreasing from a regional average of 30% above hydrostatic pressure if the hypocenters begin at hydrostatic pressure to 6% above hydrostatic pressure with no pre-injection fluid. This finding suggests that underpressured regions such as northern Oklahoma are predisposed to injection-induced earthquakes. Although retrospective and forensic, similar analyses of other potentially induced events and comparisons to natural earthquakes will provide insight into the relative importance of fault orientation, the magnitude of the local stress field, and fluid-pressure migration in intraplate seismicity.

Effect of Injection Pressure of Infiltration Anesthesia to the Jawbone.

PubMed

Yoshida, Kenji; Tanaka, Eri; Kawaai, Hiroyoshi; Yamazaki, Shinya

To obtain effective infiltration anesthesia in the jawbone, high concentrations of local anesthetic are needed. However, to reduce pain experienced by patients during local anesthetic administration, low-pressure injection is recommended for subperiosteal infiltration anesthesia. Currently, there are no studies regarding the effect of injection pressure on infiltration anesthesia, and a standard injection pressure has not been clearly determined. Hence, the effect of injection pressure of subperiosteal infiltration anesthesia on local anesthetic infiltration to the jawbone was considered by directly measuring lidocaine concentration in the jawbone. Japanese white male rabbits were used as test animals. After inducing general anesthesia with oxygen and sevoflurane, cannulation to the femoral artery was performed and arterial pressure was continuously recorded. Subperiosteal infiltration anesthesia was performed by injecting 0.5 mL of 2% lidocaine containing 1/80,000 adrenaline, and injection pressure was monitored by a pressure transducer for 40 seconds. After specified time intervals (10, 20, 30, 40, 50, and 60 minutes), jawbone and blood samples were collected, and the concentration of lidocaine at each time interval was measured. The mean injection pressure was divided into 4 groups (100 ± 50 mm Hg, 200 ± 50 mm Hg, 300 ± 50 mm Hg, and 400 ± 50 mm Hg), and comparison statistical analysis between these 4 groups was performed. No significant change in blood pressure during infiltration anesthesia was observed in any of the 4 groups. Lidocaine concentration in the blood and jawbone were highest 10 minutes after the infiltration anesthesia in all 4 groups and decreased thereafter. Lidocaine concentration in the jawbone increased as injection pressure increased, while serum lidocaine concentration was significantly lower. This suggests that when injection pressure of subperiosteal infiltration anesthesia is low, infiltration of local anesthetic to the jawbone may be reduced, while transfer to oral mucosa and blood may be increased.

Effect of Injection Pressure of Infiltration Anesthesia to the Jawbone

PubMed Central

Yoshida, Kenji; Tanaka, Eri; Kawaai, Hiroyoshi; Yamazaki, Shinya

2016-01-01

To obtain effective infiltration anesthesia in the jawbone, high concentrations of local anesthetic are needed. However, to reduce pain experienced by patients during local anesthetic administration, low-pressure injection is recommended for subperiosteal infiltration anesthesia. Currently, there are no studies regarding the effect of injection pressure on infiltration anesthesia, and a standard injection pressure has not been clearly determined. Hence, the effect of injection pressure of subperiosteal infiltration anesthesia on local anesthetic infiltration to the jawbone was considered by directly measuring lidocaine concentration in the jawbone. Japanese white male rabbits were used as test animals. After inducing general anesthesia with oxygen and sevoflurane, cannulation to the femoral artery was performed and arterial pressure was continuously recorded. Subperiosteal infiltration anesthesia was performed by injecting 0.5 mL of 2% lidocaine containing 1/80,000 adrenaline, and injection pressure was monitored by a pressure transducer for 40 seconds. After specified time intervals (10, 20, 30, 40, 50, and 60 minutes), jawbone and blood samples were collected, and the concentration of lidocaine at each time interval was measured. The mean injection pressure was divided into 4 groups (100 ± 50 mm Hg, 200 ± 50 mm Hg, 300 ± 50 mm Hg, and 400 ± 50 mm Hg), and comparison statistical analysis between these 4 groups was performed. No significant change in blood pressure during infiltration anesthesia was observed in any of the 4 groups. Lidocaine concentration in the blood and jawbone were highest 10 minutes after the infiltration anesthesia in all 4 groups and decreased thereafter. Lidocaine concentration in the jawbone increased as injection pressure increased, while serum lidocaine concentration was significantly lower. This suggests that when injection pressure of subperiosteal infiltration anesthesia is low, infiltration of local anesthetic to the jawbone may be reduced, while transfer to oral mucosa and blood may be increased. PMID:27585416

Influence of the Bermuda High on interannual variability of summertime ozone in the Houston-Galveston-Brazoria region

NASA Astrophysics Data System (ADS)

Wang, Yuxuan; Jia, Beixi; Wang, Sing-Chun; Estes, Mark; Shen, Lu; Xie, Yuanyu

2016-12-01

The Bermuda High (BH) quasi-permanent pressure system is the key large-scale circulation pattern influencing summertime weather over the eastern and southern US. Here we developed a multiple linear regression (MLR) model to characterize the effect of the BH on year-to-year changes in monthly-mean maximum daily 8 h average (MDA8) ozone in the Houston-Galveston-Brazoria (HGB) metropolitan region during June, July, and August (JJA). The BH indicators include the longitude of the BH western edge (BH-Lon) and the BH intensity index (BHI) defined as the pressure gradient along its western edge. Both BH-Lon and BHI are selected by MLR as significant predictors (p < 0.05) of the interannual (1990-2015) variability of the HGB-mean ozone throughout JJA, while local-scale meridional wind speed is selected as an additional predictor for August only. Local-scale temperature and zonal wind speed are not identified as important factors for any summer month. The best-fit MLR model can explain 61-72 % of the interannual variability of the HGB-mean summertime ozone over 1990-2015 and shows good performance in cross-validation (R2 higher than 0.48). The BH-Lon is the most important factor, which alone explains 38-48 % of such variability. The location and strength of the Bermuda High appears to control whether or not low-ozone maritime air from the Gulf of Mexico can enter southeastern Texas and affect air quality. This mechanism also applies to other coastal urban regions along the Gulf Coast (e.g., New Orleans, LA, Mobile, AL, and Pensacola, FL), suggesting that the BH circulation pattern can affect surface ozone variability through a large portion of the Gulf Coast.

Localized bulging in an inflated cylindrical tube of arbitrary thickness - the effect of bending stiffness

NASA Astrophysics Data System (ADS)

Fu, Y. B.; Liu, J. L.; Francisco, G. S.

2016-05-01

We study localized bulging of a cylindrical hyperelastic tube of arbitrary thickness when it is subjected to the combined action of inflation and axial extension. It is shown that with the internal pressure P and resultant axial force F viewed as functions of the azimuthal stretch on the inner surface and the axial stretch, the bifurcation condition for the initiation of a localized bulge is that the Jacobian of the vector function (P , F) should vanish. This is established using the dynamical systems theory by first computing the eigenvalues of a certain eigenvalue problem governing incremental deformations, and then deriving the bifurcation condition explicitly. The bifurcation condition is valid for all loading conditions, and in the special case of fixed resultant axial force it gives the expected result that the initiation pressure for localized bulging is precisely the maximum pressure in uniform inflation. It is shown that even if localized bulging cannot take place when the axial force is fixed, it is still possible if the axial stretch is fixed instead. The explicit bifurcation condition also provides a means to quantify precisely the effect of bending stiffness on the initiation pressure. It is shown that the (approximate) membrane theory gives good predictions for the initiation pressure, with a relative error less than 5%, for thickness/radius ratios up to 0.67. A two-term asymptotic bifurcation condition for localized bulging that incorporates the effect of bending stiffness is proposed, and is shown to be capable of giving extremely accurate predictions for the initiation pressure for thickness/radius ratios up to as large as 1.2.

Blood pressure associated with sleep-disordered breathing in a population sample of children.

PubMed

Bixler, Edward O; Vgontzas, Alexandros N; Lin, Hung-Mo; Liao, Duanping; Calhoun, Susan; Fedok, Fred; Vlasic, Vukmir; Graff, Gavin

2008-11-01

The current criteria for sleep-disordered breathing (SDB) in children are not based on a clinically relevant outcome. The purpose of this study was to assess the association of blood pressure with SDB in a random sample of the local elementary school children (kindergarten through grade 5) using a 2-phased strategy. During phase 1, a brief questionnaire was completed for all of the children (N=5740) with a response rate of 78.5%. During phase 2, 700 randomly selected children from phase 1 with a response rate of 70.0% were assessed with a full polysomnograph and a history/physical, including an ECG; ear, nose, and throat; and pulmonary evaluation. We observed a significantly elevated systolic blood pressure associated with the apnea hypopnea index (AHI): AHI >or=1 (2.9 mm Hg); AHI >or=3 (7.1 mm Hg); and AHI >or=5 (12.9 mm Hg). The SDB and blood pressure association remained significant after adjusting for age, sex, race, body mass index percentile or waist circumference, sleep efficiency, percentage of rapid eye movement sleep, and snoring. In addition, older age, body mass index percentile, waist circumference, and snoring were significantly associated with blood pressure, independent of SDB. Based on these findings, our study suggests that SDB is significantly associated with higher levels of systolic blood pressure in children aged 5 to 12 years even after adjusting for the various confounding factors. Clinically, the data support the threshold of AHI >or=5 for the initiation of treatment for SDB. Additional research is indicated to assess the efficacy of SDB treatment on reducing blood pressure.

Localized etching of an insulator film coated on a copper wire using an atmospheric-pressure microplasma jet.

PubMed

Yoshiki, Hiroyuki

2007-04-01

Atmospheric-pressure microplasma jets (APmicroPJs) of Ar and ArO(2) gases were generated from the tip of a stainless steel surgical needle having outer and inner diameters of 0.4 and 0.2 mm, respectively, with a rf excitation of 13.56 MHz. The steel needle functions both as a powered electrode and a gas nozzle. The operating power is 1.2-6 W and the corresponding peak-to-peak voltage Vp.p. is about 1.5 kV. The APmicroPJ was applied to the localized etching of a polyamide-imide insulator film (thickness of 10 microm) of a copper winding wire of 90 microm diameter. The insulator film around the copper wire was completely removed by the irradiated plasma from a certain direction without fusing the wire. The removal time under the Ar APmicroPJ irradiation was only 3 s at a rf power of 4 W. Fluorescence microscopy and scanning electron microscope images reveal that good selectivity of the insulator film to the copper wire was achieved. In the case of ArO(2) APmicroPJ irradiation with an O(2) concentration of 10% or more, the removed copper surface was converted to copper monoxide CuO.

Localized etching of polymer films using an atmospheric pressure air microplasma jet

NASA Astrophysics Data System (ADS)

Guo, Honglei; Liu, Jingquan; Yang, Bin; Chen, Xiang; Yang, Chunsheng

2015-01-01

A direct-write process device based on the atmospheric pressure air microplasma jet (AμPJ) has been developed for the localized etching of polymer films. The plasma was generated by the air discharge ejected out through a tip-nozzle (inner diameter of 100 μm), forming the microplasma jet. The AμPJ was capable of reacting with the polymer surface since it contains a high concentration of oxygen reactive species and thus resulted in the selective removal of polymer films. The experimental results demonstrated that the AμPJ could fabricate different microstructures on a parylene-C film without using any masks or causing any heat damage. The etch rate of parylene-C reached 5.1 μm min-1 and microstructures of different depth and width could also be realized by controlling two process parameters, namely, the etching time and the distance between the nozzle and the substrate. In addition, combining XPS analysis and oxygen-induced chemical etching principles, the potential etching mechanism of parylene-C by the AμPJ was investigated. Aside from the etching of parylene-C, micro-holes on the photoresist and polyimide film were successfully created by the AμPJ. In summary, maskless pattern etching of polymer films could be achieved using this AμPJ.

Continuous and discontinuous phase transitions in the evolution of a polygenic trait under stabilizing selective pressure

NASA Astrophysics Data System (ADS)

Fierro, Annalisa; Cocozza, Sergio; Monticelli, Antonella; Scala, Giovanni; Miele, Gennaro

2017-06-01

The presence of phenomena analogous to phase transition in Statistical Mechanics has been suggested in the evolution of a polygenic trait under stabilizing selection, mutation and genetic drift. By using numerical simulations of a model system, we analyze the evolution of a population of N diploid hermaphrodites in random mating regime. The population evolves under the effect of drift, selective pressure in form of viability on an additive polygenic trait, and mutation. The analysis allows to determine a phase diagram in the plane of mutation rate and strength of selection. The involved pattern of phase transitions is characterized by a line of critical points for weak selective pressure (smaller than a threshold), whereas discontinuous phase transitions, characterized by metastable hysteresis, are observed for strong selective pressure. A finite-size scaling analysis suggests the analogy between our system and the mean-field Ising model for selective pressure approaching the threshold from weaker values. In this framework, the mutation rate, which allows the system to explore the accessible microscopic states, is the parameter controlling the transition from large heterozygosity ( disordered phase) to small heterozygosity ( ordered one).

Combination of a total free forearm flap and a sensate local flap for preservation of the shoulder girdle in massive, nonreplantable upper extremity injuries.

PubMed

Jakubietz, Rafael G; Jakubietz, Michael G; Kloss, Danni F; Gruenert, Joerg G

2009-02-01

After massive upper extremity injuries, prosthetic use might be complicated by the formation of pressure ulcerations. Especially the coverage with insensate free flaps may predispose the patient for developing chronic ulcerations when using an upper extremity prosthesis. This complication may be reduced when sensate local flaps are used to cover bony prominences. A new operative technique is described. Immediate sensate soft tissue coverage improves prosthetic fitting. Successful manipulation of the prosthesis can be quickly achieved with a decreased risk for pressure ulceration. This challenging procedure helps to achieve durable and sensate coverage of bony prominences. The use of local sensate tissue to cover bony prominences reduces the risk for pressure ulceration when wearing a prosthesis. Areas where prosthetic use causes only low pressure and shearing forces are adequately covered with free flaps. Immediate sensibility of local flaps allows prosthetic fitting and use as soon as wound healing has occurred. Return to work is thus expedited.

Knee Cartilage Thickness, T1ρ and T2 Relaxation Time Are Related to Articular Cartilage Loading in Healthy Adults

PubMed Central

Van Rossom, Sam; Smith, Colin Robert; Zevenbergen, Lianne; Thelen, Darryl Gerard; Vanwanseele, Benedicte; Van Assche, Dieter; Jonkers, Ilse

2017-01-01

Cartilage is responsive to the loading imposed during cyclic routine activities. However, the local relation between cartilage in terms of thickness distribution and biochemical composition and the local contact pressure during walking has not been established. The objective of this study was to evaluate the relation between cartilage thickness, proteoglycan and collagen concentration in the knee joint and knee loading in terms of contact forces and pressure during walking. 3D gait analysis and MRI (3D-FSE, T1ρ relaxation time and T2 relaxation time sequence) of fifteen healthy subjects were acquired. Experimental gait data was processed using musculoskeletal modeling to calculate the contact forces, impulses and pressure distribution in the tibiofemoral joint. Correlates to local cartilage thickness and mean T1ρ and T2 relaxation times of the weight-bearing area of the femoral condyles were examined. Local thickness was significantly correlated with local pressure: medial thickness was correlated with medial condyle contact pressure and contact force, and lateral condyle thickness was correlated with lateral condyle contact pressure and contact force during stance. Furthermore, average T1ρ and T2 relaxation time correlated significantly with the peak contact forces and impulses. Increased T1ρ relaxation time correlated with increased shear loading, decreased T1ρ and T2 relaxation time correlated with increased compressive forces and pressures. Thicker cartilage was correlated with higher condylar loading during walking, suggesting that cartilage thickness is increased in those areas experiencing higher loading during a cyclic activity such as gait. Furthermore, the proteoglycan and collagen concentration and orientation derived from T1ρ and T2 relaxation measures were related to loading. PMID:28076431

An Application of the Methodology for Assessment of the Sustainability of Air Transport System

NASA Technical Reports Server (NTRS)

Janic, Milan

2003-01-01

An assessment and operationalization of the concept of sustainable air transport system is recognized as an important but complex research, operational and policy task. In the scope of the academic efforts to properly address the problem, this paper aims to assess the sustainability of air transport system. It particular, the paper describes the methodology for assessment of sustainability and its potential application. The methodology consists of the indicator systems, which relate to the air transport system operational, economic, social and environmental dimension of performance. The particular indicator systems are relevant for the particular actors such users (air travellers), air transport operators, aerospace manufacturers, local communities, governmental authorities at different levels (local, national, international), international air transport associations, pressure groups and public. In the scope of application of the methodology, the specific cases are selected to estimate the particular indicators, and thus to assess the system sustainability under given conditions.

Genome scanning for detecting adaptive genes along environmental gradients in the Japanese conifer, Cryptomeria japonica.

PubMed

Tsumura, Y; Uchiyama, K; Moriguchi, Y; Ueno, S; Ihara-Ujino, T

2012-12-01

Local adaptation is important in evolutionary processes and speciation. We used multiple tests to identify several candidate genes that may be involved in local adaptation from 1026 loci in 14 natural populations of Cryptomeria japonica, the most economically important forestry tree in Japan. We also studied the relationships between genotypes and environmental variables to obtain information on the selective pressures acting on individual populations. Outlier loci were mapped onto a linkage map, and the positions of loci associated with specific environmental variables are considered. The outlier loci were not randomly distributed on the linkage map; linkage group 11 was identified as a genomic island of divergence. Three loci in this region were also associated with environmental variables such as mean annual temperature, daily maximum temperature, maximum snow depth, and so on. Outlier loci identified with high significance levels will be essential for conservation purposes and for future work on molecular breeding.

The localized effect of the Bi level on the valence band in the dilute bismuth GaBixAs1-x alloy

NASA Astrophysics Data System (ADS)

Zhao, Chuan-Zhen; Zhu, Min-Min; Wang, Jun; Wang, Sha-Sha; Lu, Ke-Qing

2018-05-01

The research on the temperature dependence of the band gap energy of the dilute bismuth GaBixAs1-x alloy has been done. It is found that its temperature insensitiveness is due to the enhanced localized character of the valence band state and the small decrease of the temperature coefficient for the conduction band minimum (CBM). The enhanced localized character of the valence band state is the main factor. In order to describe the localized effect of the Bi levels on the valence band, the localized energy is introduced into the Varshni's equation. It is found that the effect of the localized Bi level on the valence band becomes strong with increasing Bi content. In addition, it is found that the pressure dependence of the band gap energy of GaBixAs1-x does not seem to be influenced by the localized Bi levels. It is due to two factors. One is that the pressure dependence of the band gap energy is mainly determined by the D CBM of GaBixAs1-x. The D CBM of GaBixAs1-x is not influenced by the localized Bi levels. The other is that the small variation of the pressure coefficient for the D valence band maximum (VBM) state of GaBixAs1-x can be cancelled by the variation of the pressure coefficient for the D CBM state of GaBixAs1-x.

Compressed storage of arterial pressure waveforms by selection of significant points.

PubMed

de Graaf, P M; van Goudoever, J; Wesseling, K H

1997-09-01

Continuous records of arterial blood pressure can be obtained non-invasively with Finapres, even for periods of 24 hours. Increasingly, storage of such records is done digitally, requiring large disc capacities. It is therefore necessary to find methods to store blood pressure waveforms in compressed form. The method of selection of significant points known from ECG data compression is adapted. Points are selected as significant wherever the first derivative of the pressure wave changes sign. As a second stage recursive partitioning is used to select additional points such that the difference between the selected points, linearly interpolated, and the original curve remains below a maximum. This method is tested on finger arterial pressure waveform epochs of 60 s duration taken from 32 patients with a wide range of blood pressures and heart rates. An average compression factor of 4.6 (SD 1.0) is obtained when accepting a maximum difference of 3 mmHg. The root mean squared error is 1 mmHg averaged over the group of patient waveforms. Clinically relevant parameters such as systolic, diastolic and mean pressure are reproduced with an offset error of less than 0.5 (0.3) mmHg and scatter less than 0.6 (0.1) mmHg. It is concluded that a substantial compression factor can be achieved with a simple and computationally fast algorithm and little deterioration in waveform quality and pressure level accuracy.

Behavioural correlates of urbanisation in the Cape ground squirrel Xerus inauris

NASA Astrophysics Data System (ADS)

Chapman, Tarryn; Rymer, Tasmin; Pillay, Neville

2012-11-01

Urbanisation critically threatens biodiversity because of habitat destruction and novel selection pressures. Some animals can respond to these challenges by modifying their behaviour, particularly anti-predator behaviour, allowing them to persist in heavily transformed urban areas. We investigated whether the anti-predator behaviour of the Cape ground squirrel Xerus inauris differed in three localities that differed in their level of urbanisation. According to the habituation hypothesis, we predicted that ground squirrels in urban areas would: (a) be less vigilant and forage more; (b) trade-off flight/vigilance in favour of foraging; and (c) have shorter flight initiation distances (FID) when approached by a human observer. Observations were made in winter and summer at each locality. As expected, ground squirrels in urbanised areas were less vigilant and had shorter FIDs but did not trade-off between foraging and vigilance. In contrast, a population in a non-urbanised locality showed greater levels of vigilance, FID and traded-off vigilance and foraging. A population in a peri-urban locality showed mixed responses. Our results indicate that Cape ground squirrels reduce their anti-predator behaviour in urban areas and demonstrate a flexible behavioural response to urbanisation.

Oximetry: a new non-invasive method to detect metabolic effects induced by a local application of mechanical vibration

NASA Astrophysics Data System (ADS)

Felici, A.; Trombetta, C.; Abundo, P.; Foti, C.; Rosato, N.

2012-10-01

Mechanical vibrations application is increasingly common in clinical practice due to the effectiveness induced by these stimuli on the human body. Local vibration (LV) application allows to apply and act only where needed, focusing the treatment on the selected body segment. An experimental device for LV application was used to generate the vibrations. The aim of this study was to detect and analyze the metabolic effects induced by LV on the brachial bicep muscle by means of an oximeter. This device monitors tissue and muscle oxygenation using NIRS (Near Infrared Spectroscopy) and is able to determine the concentration of haemoglobin and oxygen saturation in the tissue. In a preliminary stage we also investigated the effects induced by LV application, by measuring blood pressure, heart rate, oxygen saturation and temperature. These data confirmed that the effects induced by LV application are actually localized. The results of the measurements obtained using the oximeter during the vibration application, have shown a variation of the concentrations. In particular an increase of oxygenate haemoglobin was shown, probably caused by an increased muscle activity and/or a rise in local temperature detected during the application.

Behavioural correlates of urbanisation in the Cape ground squirrel Xerus inauris.

PubMed

Chapman, Tarryn; Rymer, Tasmin; Pillay, Neville

2012-11-01

Urbanisation critically threatens biodiversity because of habitat destruction and novel selection pressures. Some animals can respond to these challenges by modifying their behaviour, particularly anti-predator behaviour, allowing them to persist in heavily transformed urban areas. We investigated whether the anti-predator behaviour of the Cape ground squirrel Xerus inauris differed in three localities that differed in their level of urbanisation. According to the habituation hypothesis, we predicted that ground squirrels in urban areas would: (a) be less vigilant and forage more; (b) trade-off flight/vigilance in favour of foraging; and (c) have shorter flight initiation distances (FID) when approached by a human observer. Observations were made in winter and summer at each locality. As expected, ground squirrels in urbanised areas were less vigilant and had shorter FIDs but did not trade-off between foraging and vigilance. In contrast, a population in a non-urbanised locality showed greater levels of vigilance, FID and traded-off vigilance and foraging. A population in a peri-urban locality showed mixed responses. Our results indicate that Cape ground squirrels reduce their anti-predator behaviour in urban areas and demonstrate a flexible behavioural response to urbanisation.

The importance of Thermo-Hydro-Mechanical couplings and microstructure to strain localization in 3D continua with application to seismic faults. Part I: Theory and linear stability analysis

NASA Astrophysics Data System (ADS)

Rattez, Hadrien; Stefanou, Ioannis; Sulem, Jean

2018-06-01

A Thermo-Hydro-Mechanical (THM) model for Cosserat continua is developed to explore the influence of frictional heating and thermal pore fluid pressurization on the strain localization phenomenon. A general framework is presented to conduct a bifurcation analysis for elasto-plastic Cosserat continua with THM couplings and predict the onset of instability. The presence of internal lengths in Cosserat continua enables to estimate the thickness of the localization zone. This is done by performing a linear stability analysis of the system and looking for the selected wavelength corresponding to the instability mode with fastest finite growth coefficient. These concepts are applied to the study of fault zones under fast shearing. For doing so, we consider a model of a sheared saturated infinite granular layer. The influence of THM couplings on the bifurcation state and the shear band width is investigated. Taking representative parameters for a centroidal fault gouge, the evolution of the thickness of the localized zone under continuous shear is studied. Furthermore, the effect of grain crushing inside the shear band is explored by varying the internal length of the constitutive law.

Diamagnetic susceptibility: An indicator of pressure induced donor localization in a double quantum well

NASA Astrophysics Data System (ADS)

Vignesh, G.; Nithiananthi, P.

2016-04-01

The influence of pressure along the growth axis on carrier localization in GaAs/Al0.3Ga0.7As Double Quantum Well (DQW) is studied under strongly coupled regime and isolated regimes of the well. The effective mass approximation combined with variation technique is adopted with the inclusion of mismatches in effective mass and dielectric constants of the well and barrier material. Effect of the barrier and well on carrier localization is investigated by observing the diamagnetic susceptibility (χdia) for various impurity locations (zi) and the critical limit of the barrier (Lb ≈ 50 Å) for tunneling has also been estimated. The effect of Γ-Χ crossover due to the application of pressure on the donor localization is picturized through diamagnetic susceptibility.

Enhanced densification under shock compression in porous silicon

NASA Astrophysics Data System (ADS)

Lane, J. Matthew D.; Thompson, Aidan P.; Vogler, Tracy J.

2014-10-01

Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. We demonstrate a molecular mechanism that drives this behavior. We also present evidence from atomistic simulation that silicon belongs to this anomalous class of materials. Atomistic simulations indicate that local shear strain in the neighborhood of collapsing pores nucleates a local solid-solid phase transformation even when bulk pressures are below the thermodynamic phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.

Volume-controlled Ventilation Does Not Prevent Injurious Inflation during Spontaneous Effort.

PubMed

Yoshida, Takeshi; Nakahashi, Susumu; Nakamura, Maria Aparecida Miyuki; Koyama, Yukiko; Roldan, Rollin; Torsani, Vinicius; De Santis, Roberta R; Gomes, Susimeire; Uchiyama, Akinori; Amato, Marcelo B P; Kavanagh, Brian P; Fujino, Yuji

2017-09-01

Spontaneous breathing during mechanical ventilation increases transpulmonary pressure and Vt, and worsens lung injury. Intuitively, controlling Vt and transpulmonary pressure might limit injury caused by added spontaneous effort. To test the hypothesis that, during spontaneous effort in injured lungs, limitation of Vt and transpulmonary pressure by volume-controlled ventilation results in less injurious patterns of inflation. Dynamic computed tomography was used to determine patterns of regional inflation in rabbits with injured lungs during volume-controlled or pressure-controlled ventilation. Transpulmonary pressure was estimated by using esophageal balloon manometry [Pl(es)] with and without spontaneous effort. Local dependent lung stress was estimated as the swing (inspiratory change) in transpulmonary pressure measured by intrapleural manometry in dependent lung and was compared with the swing in Pl(es). Electrical impedance tomography was performed to evaluate the inflation pattern in a larger animal (pig) and in a patient with acute respiratory distress syndrome. Spontaneous breathing in injured lungs increased Pl(es) during pressure-controlled (but not volume-controlled) ventilation, but the pattern of dependent lung inflation was the same in both modes. In volume-controlled ventilation, spontaneous effort caused greater inflation and tidal recruitment of dorsal regions (greater than twofold) compared with during muscle paralysis, despite the same Vt and Pl(es). This was caused by higher local dependent lung stress (measured by intrapleural manometry). In injured lungs, esophageal manometry underestimated local dependent pleural pressure changes during spontaneous effort. Limitation of Vt and Pl(es) by volume-controlled ventilation could not eliminate harm caused by spontaneous breathing unless the level of spontaneous effort was lowered and local dependent lung stress was reduced.

Cryo-Compression System in a 3000 Ton Multi-Anvil Press

NASA Astrophysics Data System (ADS)

Secco, R. A.; Yong, W.

2016-12-01

Most large volume high pressure devices are capable of high temperature experiments that are typically achieved by using localized resistive heating of a metal foil, graphite or ceramic sleeve inside a thermally insulated sample volume in a high pressure cell. Low temperatures at high pressures are needed for physical property studies of materials that comprise planetary bodies in the outer solar system. However, low temperatures are more difficult to achieve mainly because the massive steel components of the press, which are in good thermal contact with each other under high load, act as large heat reservoirs and pathways that encumber the removal of heat from the pressure cell. We describe a new custom-designed system under development for a 3000 ton multi-anvil press to reach temperatures below 295K at high pressures. The system was designed to remove heat selectively and conductively from the sample volume through six of the eight WC cubes in direct contact with the octahedral pressure cell. Cooling fins made of Cu are sandwiched between, and in thermal contact with, neighboring anvil faces and are each connected to a dedicated Cu heat exchanger chamber through which liquid nitrogen flows. The chamber internal geometry consists of either square pillars that double the internal surface area of the rectangular parallelepiped enclosed volume or continuous walls separated by valleys. Gas from each chamber is vented to the lab through an exhaust pipe. High pressure results will be presented of several temperature monitoring points in the center of the pressure cell and on the surfaces of the WC cubes and steel wedges which recorded the time-dependent cooling progress. Temperature stability tests will also be presented.

Competition and Curriculum Diversity in Local Schooling Markets: Theory and Evidence.

ERIC Educational Resources Information Center

Adnett, Nick; Davies, Peter

2000-01-01

Based on conventional economic analysis, increasing competitive pressures on schools should promote greater curricular innovation and diversity. The United Kingdom's experience suggests that market-based reforms can initially create pressures to increase curriculum conformity in local schooling markets. Innovation incentives are greatest for…

Chirp- and random-based coded ultrasonic excitation for localized blood-brain barrier opening

PubMed Central

Kamimura, HAS; Wang, S; Wu, S-Y; Karakatsani, ME; Acosta, C; Carneiro, AAO; Konofagou, EE

2015-01-01

Chirp- and random-based coded excitation methods have been proposed to reduce standing wave formation and improve focusing of transcranial ultrasound. However, no clear evidence has been shown to support the benefits of these ultrasonic excitation sequences in vivo. This study evaluates the chirp and periodic selection of random frequency (PSRF) coded-excitation methods for opening the blood-brain barrier (BBB) in mice. Three groups of mice (n=15) were injected with polydisperse microbubbles and sonicated in the caudate putamen using the chirp/PSRF coded (bandwidth: 1.5-1.9 MHz, peak negative pressure: 0.52 MPa, duration: 30 s) or standard ultrasound (frequency: 1.5 MHz, pressure: 0.52 MPa, burst duration: 20 ms, duration: 5 min) sequences. T1-weighted contrast-enhanced MRI scans were performed to quantitatively analyze focused ultrasound induced BBB opening. The mean opening volumes evaluated from the MRI were 9.38±5.71 mm3, 8.91±3.91 mm3 and 35.47 ± 5.10 mm3 for the chirp, random and regular sonications, respectively. The mean cavitation levels were 55.40±28.43 V.s, 63.87±29.97 V.s and 356.52±257.15 V.s for the chirp, random and regular sonications, respectively. The chirp and PSRF coded pulsing sequences improved the BBB opening localization by inducing lower cavitation levels and smaller opening volumes compared to results of the regular sonication technique. Larger bandwidths were associated with more focused targeting but were limited by the frequency response of the transducer, the skull attenuation and the microbubbles optimal frequency range. The coded methods could therefore facilitate highly localized drug delivery as well as benefit other transcranial ultrasound techniques that use higher pressure levels and higher precision to induce the necessary bioeffects in a brain region while avoiding damage to the surrounding healthy tissue. PMID:26394091

Emergent high-spin state above 7 GPa in superconducting FeSe

NASA Astrophysics Data System (ADS)

Lebert, B. W.; Balédent, V.; Toulemonde, P.; Ablett, J. M.; Rueff, J.-P.

2018-05-01

The local electronic and magnetic properties of superconducting FeSe have been investigated by K β x-ray emission and simultaneous x-ray absorption spectroscopy (XAS) at the Fe K edge at high pressure and low temperature. Our results indicate a sluggish decrease of the local Fe spin moment under pressure up to 7 GPa, in line with previous reports, followed by a sudden increase at higher pressure. The magnetic surge is preceded by an abrupt change of the Fe local structure as observed by the decrease of the XAS preedge region intensity and corroborated by ab initio simulations. This pressure corresponds to a structural transition from the C m m a form to the denser P b n m form with octahedral coordination of iron. Finally, the near-edge region of the XAS spectra shows a change before this transition at 5 GPa, corresponding well with the onset pressure of the sudden enhancement of Tc. Our results emphasize the delicate interplay between structural, magnetic, and superconducting properties in FeSe under pressure.

Controlling and assessing pressure conditions during treatment of tar sands formations

DOEpatents

Zhang, Etuan; Beer, Gary Lee

2015-11-10

A method for treating a tar sands formation includes providing heat to at least part of a hydrocarbon layer in the tar sands formation from a plurality of heaters located in the formation. Heat is allowed to transfer from the heaters to at least a portion of the formation. A pressure in the portion of the formation is controlled such that the pressure remains below a fracture pressure of the formation overburden while allowing the portion of the formation to heat to a selected average temperature of at least about 280.degree. C. and at most about 300.degree. C. The pressure in the portion of the formation is reduced to a selected pressure after the portion of the formation reaches the selected average temperature.

Dome of magnetic order inside the nematic phase of sulfur-substituted FeSe under pressure

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

Xiang, Li; Kaluarachchi, Udhara; Bohmer, Anna

2017-07-18

The pressure dependence of the structural, magnetic, and superconducting transitions and of the superconducting upper critical field were studied in sulfur-substituted Fe ( Se 1 - x S x ) . We performed resistance measurements on single crystals with three substitution levels ( x = 0.043 , 0.096, 0.12) under hydrostatic pressures up to 1.8 GPa and in magnetic fields up to 9 T and were compared to data on pure FeSe. Our results illustrate the effects of chemical and physical pressure on Fe ( Se 1 - x S x ). Furthermore, on increasing sulfur content, magnetic order inmore » the low-pressure range is strongly suppressed to a small domelike region in the phase diagrams. But, T s is much less suppressed by sulfur substitution, and T c of Fe ( Se 1 - x S x ) exhibits similar nonmonotonic pressure dependence with a local maximum and a local minimum present in the low-pressure range for all x . The local maximum in T c coincides with the emergence of the magnetic order above T c . At this pressure the slope of the upper critical field decreases abruptly, which may indicate a Fermi-surface reconstruction. The minimum of T c correlates with a broad maximum of the upper critical field slope normalized by T c .« less

Analysis of morphological variability and heritability in the head of the Argentine Black and White Tegu (Salvator merianae): undisturbed vs. disturbed environments.

PubMed

Imhoff, Carolina; Giri, Federico; Siroski, Pablo; Amavet, Patricia

2018-04-01

The heterogeneity of biotic and abiotic factors influencing fitness produce selective pressures that promote local adaptation and divergence among different populations of the same species. In order for adaptations to be maintained through evolutionary time, heritable genetic variation controlling the expression of the morphological features under selection is necessary. Here we compare morphological shape variability and size of the cephalic region of Salvator merianae specimens from undisturbed environments to those of individuals from disturbed environments, and estimated heritability for shape and size using geometric morphometric and quantitative genetics tools. The results of these analyzes indicated that there are statistically significant differences in shape and size between populations from the two environments. Possibly, one of the main determinants of cephalic shape and size is adaptation to the characteristics of the environment and to the trophic niche. Individuals from disturbed environments have a cephalic region with less shape variation and also have a larger centroid size when compared to individuals from undisturbed environments. The high heritability values obtained for shape and size in dorsal view and right side view indicate that these phenotypic characters have a great capacity to respond to the selection pressures to which they are subjected. Data obtained here could be used as an important tool when establishing guidelines for plans for the sustainable use and conservation of S. merianae and other species living in disturbed areas. Copyright © 2018 Elsevier GmbH. All rights reserved.

Calculation of Local Stress and Fatigue Resistance due to Thermal Stratification on Pressurized Surge Line Pipe

NASA Astrophysics Data System (ADS)

Bandriyana, B.; Utaja

2010-06-01

Thermal stratification introduces thermal shock effect which results in local stress and fatique problems that must be considered in the design of nuclear power plant components. Local stress and fatique calculation were performed on the Pressurize Surge Line piping system of the Pressurize Water Reactor of the Nuclear Power Plant. Analysis was done on the operating temperature between 177 to 343° C and the operating pressure of 16 MPa (160 Bar). The stagnant and transient condition with two kinds of stratification model has been evaluated by the two dimensional finite elements method using the ANSYS program. Evaluation of fatigue resistance is developed based on the maximum local stress using the ASME standard Code formula. Maximum stress of 427 MPa occurred at the upper side of the top half of hot fluid pipe stratification model in the transient case condition. The evaluation of the fatigue resistance is performed on 500 operating cycles in the life time of 40 years and giving the usage value of 0,64 which met to the design requirement for class 1 of nuclear component. The out surge transient were the most significant case in the localized effects due to thermal stratification.

Strongly localized donor level in oxygen doped gallium nitride

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

Wetzel, C.; Suski, T.; Ager, J.W. III

1996-08-01

A classification in terms of localization of donor defects in GaN is performed by Raman spectroscopy under large hydrostatic pressure. We observe a significant decrease of free carrier concentration in highly O doped GaN epitaxial films at 22 GPa, indicating the presence of a strongly localized donor defect at large pressure. Monitoring the phonon plasmon coupled mode, we find similarities with results on highly n-type bulk crystals. We refine the model of localized defects in GaN and transfer it to the AlGaN system.

Signatures of positive selection in African Butana and Kenana dairy zebu cattle

PubMed Central

Salim, Bashir; Almathen, Faisal; Al Enezi, Fahad; Mwacharo, Joram M.; Hanotte, Olivier

2018-01-01

Butana and Kenana are two types of zebu cattle found in Sudan. They are unique amongst African indigenous zebu cattle because of their high milk production. Aiming to understand their genome structure, we genotyped 25 individuals from each breed using the Illumina BovineHD Genotyping BeadChip. Genetic structure analysis shows that both breeds have an admixed genome composed of an even proportion of indicine (0.75 ± 0.03 in Butana, 0.76 ± 0.006 in Kenana) and taurine (0.23 ± 0.009 in Butana, 0.24 ± 0.006 in Kenana) ancestries. We also observe a proportion of 0.02 to 0.12 of European taurine ancestry in ten individuals of Butana that were sampled from cattle herds in Tamboul area suggesting local crossbreeding with exotic breeds. Signatures of selection analyses (iHS and Rsb) reveal 87 and 61 candidate positive selection regions in Butana and Kenana, respectively. These regions span genes and quantitative trait loci (QTL) associated with biological pathways that are important for adaptation to marginal environments (e.g., immunity, reproduction and heat tolerance). Trypanotolerance QTL are intersecting candidate regions in Kenana cattle indicating selection pressure acting on them, which might be associated with an unexplored level of trypanotolerance in this cattle breed. Several dairy traits QTL are overlapping the identified candidate regions in these two zebu cattle breeds. Our findings underline the potential to improve dairy production in the semi-arid pastoral areas of Africa through breeding improvement strategy of indigenous local breeds. PMID:29300786

Genomic analysis of Ugandan and Rwandan chicken ecotypes using a 600 k genotyping array.

PubMed

Fleming, D S; Koltes, J E; Markey, A D; Schmidt, C J; Ashwell, C M; Rothschild, M F; Persia, M E; Reecy, J M; Lamont, S J

2016-05-26

Indigenous populations of animals have developed unique adaptations to their local environments, which may include factors such as response to thermal stress, drought, pathogens and suboptimal nutrition. The survival and subsequent evolution within these local environments can be the result of both natural and artificial selection driving the acquisition of favorable traits, which over time leave genomic signatures in a population. This study's goals are to characterize genomic diversity and identify selection signatures in chickens from equatorial Africa to identify genomic regions that may confer adaptive advantages of these ecotypes to their environments. Indigenous chickens from Uganda (n = 72) and Rwanda (n = 100), plus Kuroilers (n = 24, an Indian breed imported to Africa), were genotyped using the Axiom® 600 k Chicken Genotyping Array. Indigenous ecotypes were defined based upon location of sampling within Africa. The results revealed the presence of admixture among the Ugandan, Rwandan, and Kuroiler populations. Genes within runs of homozygosity consensus regions are linked to gene ontology (GO) terms related to lipid metabolism, immune functions and stress-mediated responses (FDR < 0.15). The genes within regions of signatures of selection are enriched for GO terms related to health and oxidative stress processes. Key genes in these regions had anti-oxidant, apoptosis, and inflammation functions. The study suggests that these populations have alleles under selective pressure from their environment, which may aid in adaptation to harsh environments. The correspondence in gene ontology terms connected to stress-mediated processes across the populations could be related to the similarity of environments or an artifact of the detected admixture.

Distribution of perfusion.

PubMed

Glenny, Robb; Robertson, H Thomas

2011-01-01

Local driving pressures and resistances within the pulmonary vascular tree determine the distribution of perfusion in the lung. Unlike other organs, these local determinants are significantly influenced by regional hydrostatic and alveolar pressures. Those effects on blood flow distribution are further magnified by the large vertical height of the human lung and the relatively low intravascular pressures in the pulmonary circulation. While the distribution of perfusion is largely due to passive determinants such as vascular geometry and hydrostatic pressures, active mechanisms such as vasoconstriction induced by local hypoxia can also redistribute blood flow. This chapter reviews the determinants of regional lung perfusion with a focus on vascular tree geometry, vertical gradients induced by gravity, the interactions between vascular and surrounding alveolar pressures, and hypoxic pulmonary vasoconstriction. While each of these determinants of perfusion distribution can be examined in isolation, the distribution of blood flow is dynamically determined and each component interacts with the others so that a change in one region of the lung influences the distribution of blood flow in other lung regions. © 2011 American Physiological Society.

Twenty-five thousand years of fluctuating selection on leopard complex spotting and congenital night blindness in horses

PubMed Central

Ludwig, Arne; Reissmann, Monika; Benecke, Norbert; Bellone, Rebecca; Sandoval-Castellanos, Edson; Cieslak, Michael; Fortes, Gloria G.; Morales-Muñiz, Arturo; Hofreiter, Michael; Pruvost, Melanie

2015-01-01

Leopard complex spotting is inherited by the incompletely dominant locus, LP, which also causes congenital stationary night blindness in homozygous horses. We investigated an associated single nucleotide polymorphism in the TRPM1 gene in 96 archaeological bones from 31 localities from Late Pleistocene (approx. 17 000 YBP) to medieval times. The first genetic evidence of LP spotting in Europe dates back to the Pleistocene. We tested for temporal changes in the LP associated allele frequency and estimated coefficients of selection by means of approximate Bayesian computation analyses. Our results show that at least some of the observed frequency changes are congruent with shifts in artificial selection pressure for the leopard complex spotting phenotype. In early domestic horses from Kirklareli–Kanligecit (Turkey) dating to 2700–2200 BC, a remarkably high number of leopard spotted horses (six of 10 individuals) was detected including one adult homozygote. However, LP seems to have largely disappeared during the late Bronze Age, suggesting selection against this phenotype in early domestic horses. During the Iron Age, LP reappeared, probably by reintroduction into the domestic gene pool from wild animals. This picture of alternating selective regimes might explain how genetic diversity was maintained in domestic animals despite selection for specific traits at different times. PMID:25487337

Io meteorology - How atmospheric pressure is controlled locally by volcanos and surface frosts

NASA Technical Reports Server (NTRS)

Ingersoll, Andrew P.

1989-01-01

The present modification of the Ingersoll et al. (1985) hydrodynamic model of the SO2 gas sublimation-driven flow from the day to the night side of Io includes the effects of nonuniform surface properties noted in observational studies. Calculations are conducted for atmospheric pressures, horizontal winds, sublimation rates, and condensation rates for such surface conditions as patchy and continuous frost cover, volcanic venting, surface temperature discontinuities, subsurface cold trapping, and the propagation of insolation into the frost. While pressure is found to follow local vapor pressure away from the plumes, it becomes higher inside them.

New numerical solutions of three-dimensional compressible hydrodynamic convection. [in stars

NASA Technical Reports Server (NTRS)

Hossain, Murshed; Mullan, D. J.

1990-01-01

Numerical solutions of three-dimensional compressible hydrodynamics (including sound waves) in a stratified medium with open boundaries are presented. Convergent/divergent points play a controlling role in the flows, which are dominated by a single frequency related to the mean sound crossing time. Superposed on these rapid compressive flows, slower eddy-like flows eventually create convective transport. The solutions contain small structures stacked on top of larger ones, with vertical scales equal to the local pressure scale heights, H sub p. Although convective transport starts later in the evolution, vertical scales of H sub p are apparently selected at much earlier times by nonlinear compressive effects.

State and Local Governments: Fiscal Pressures Could Have Implications for Future Delivery of Intergovernmental Programs. Report to the Ranking Member, Committee on the Budget, House of Representatives. GAO-10-899

ERIC Educational Resources Information Center

Czerwinski, Stanley J.

2010-01-01

State and local governments work in partnership with the federal government to implement numerous intergovernmental programs. Fiscal pressures for state and local governments may exist when spending is expected to outpace revenues for the long term. GAO (Government Accountability Office) was asked to examine (1) the long-term fiscal pressures…

Level set method with automatic selective local statistics for brain tumor segmentation in MR images.

PubMed

Thapaliya, Kiran; Pyun, Jae-Young; Park, Chun-Su; Kwon, Goo-Rak

2013-01-01

The level set approach is a powerful tool for segmenting images. This paper proposes a method for segmenting brain tumor images from MR images. A new signed pressure function (SPF) that can efficiently stop the contours at weak or blurred edges is introduced. The local statistics of the different objects present in the MR images were calculated. Using local statistics, the tumor objects were identified among different objects. In this level set method, the calculation of the parameters is a challenging task. The calculations of different parameters for different types of images were automatic. The basic thresholding value was updated and adjusted automatically for different MR images. This thresholding value was used to calculate the different parameters in the proposed algorithm. The proposed algorithm was tested on the magnetic resonance images of the brain for tumor segmentation and its performance was evaluated visually and quantitatively. Numerical experiments on some brain tumor images highlighted the efficiency and robustness of this method. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

Micro glow plasma for localized nanostructural modification of carbon nanotube forest

NASA Astrophysics Data System (ADS)

Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer; Nojeh, Alireza; Takahata, Kenichi

2016-08-01

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ˜30% and ˜300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.

Micro glow plasma for localized nanostructural modification of carbon nanotube forest

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

Sarwar, Mirza Saquib us; Xiao, Zhiming; Saleh, Tanveer

2016-08-22

This paper reports the localized selective treatment of vertically aligned carbon nanotubes, or CNT forests, for radial size modification of the nanotubes through a micro-scale glow plasma established on the material. An atmospheric-pressure DC glow plasma is shown to be stably sustained on the surface of the CNT forest in argon using micromachined tungsten electrodes with diameters down to 100 μm. Experiments reveal thinning or thickening of the nanotubes under the micro glow depending on the process conditions including discharge current and process time. These thinning and thickening effects in the treated nanotubes are measured to be up to ∼30% andmore » ∼300% in their diameter, respectively, under the tested conditions. The elemental and Raman analyses suggest that the treated region of the CNT forest is pure carbon and maintains a degree of crystallinity. The local plasma treatment process investigated may allow modification of material characteristics in different domains for targeted regions or patterns, potentially aiding custom design of micro-electro-mechanical systems and other emerging devices enabled by the CNT forest.« less

Relationship between Air Pollution and Weather Conditions under Complicated Geographical conditions

NASA Astrophysics Data System (ADS)

Cheng, Q.; Jiang, P.; Li, M.

2017-12-01

Air pollution is one of the most serious issues all over the world, especially in megacities with constrained geographical conditions for air pollution diffusion. However, the dynamic mechanism of air pollution diffusion under complicated geographical conditions is still be confused. Researches to explore relationship between air pollution and weather conditions from the perspective of local atmospheric circulations can contribute more to solve such problem. We selected three megacities (Beijing, Shanghai and Guangzhou) under different geographical condition (mountain-plain transition region, coastal alluvial plain and coastal hilly terrain) to explore the relationship between air pollution and weather conditions. RDA (Redundancy analysis) model was used to analyze how the local atmospheric circulation acts on the air pollutant diffusion. The results show that there was a positive correlation between the concentration of air pollutants and air pressure, while temperature, precipitation and wind speed have negative correlations with the concentration of air pollutants. Furthermore, geographical conditions, such as topographic relief, have significant effects on the direction, path and intensity of local atmospheric circulation. As a consequence, air pollutants diffusion modes in different cities under various geographical conditions are diverse from each other.

Geographic Variation in Camouflage Specialization by a Decorator Crab.

PubMed

Stachowicz, John J; Hay, Mark E

2000-07-01

In North Carolina, the decorator crab Libinia dubia camouflages almost exclusively with the chemically noxious alga Dictyota menstrualis. By placing this alga on its carapace, the crab behaviorally sequesters the defensive chemicals of the plant and gains protection from omnivorous consumers. However, Dictyota is absent north of North Carolina, whereas Libinia occurs as far north as New England. Crabs from three northern locations where Dictyota is absent (Rhode Island, Connecticut, and New Jersey) camouflaged to match their environment, rather than selectively accumulating any one species. When D. menstrualis was offered to crabs from northern sites, they did not distinguish between it and other seaweeds for camouflage, whereas crabs from Alabama and two locations in North Carolina used D. menstrualis almost exclusively. In addition, in winter and spring, when Dictyota was seasonally absent in North Carolina, Libinia selectively camouflaged with the sun sponge Hymeniacidon heliophila, which was chemically unpalatable to local fishes. Thus, southern crabs were consistent specialists on chemically defended species for camouflage, while northern crabs were more generalized. The geographic shift in crab behavior away from specialization coincides with a reported decrease in both total predation pressure and the frequency of omnivorous consumers. These shifts in the nature and intensity of predation pressure may favor different camouflage strategies (generalist vs. specialist), contributing to the observed geographic differences in camouflage behavior.

Prediction model for peninsular Indian summer monsoon rainfall using data mining and statistical approaches

NASA Astrophysics Data System (ADS)

Vathsala, H.; Koolagudi, Shashidhar G.

2017-01-01

In this paper we discuss a data mining application for predicting peninsular Indian summer monsoon rainfall, and propose an algorithm that combine data mining and statistical techniques. We select likely predictors based on association rules that have the highest confidence levels. We then cluster the selected predictors to reduce their dimensions and use cluster membership values for classification. We derive the predictors from local conditions in southern India, including mean sea level pressure, wind speed, and maximum and minimum temperatures. The global condition variables include southern oscillation and Indian Ocean dipole conditions. The algorithm predicts rainfall in five categories: Flood, Excess, Normal, Deficit and Drought. We use closed itemset mining, cluster membership calculations and a multilayer perceptron function in the algorithm to predict monsoon rainfall in peninsular India. Using Indian Institute of Tropical Meteorology data, we found the prediction accuracy of our proposed approach to be exceptionally good.

A critical care network pressure ulcer prevention quality improvement project.

PubMed

McBride, Joanna; Richardson, Annette

2015-03-30

Pressure ulcer prevention is an important safety issue, often underrated and an extremely painful event harming patients. Critically ill patients are one of the highest risk groups in hospital. The impact of pressure ulcers are wide ranging, and they can result in increased critical care and the hospital length of stay, significant interference with functional recovery and rehabilitation and increase cost. This quality improvement project had four aims: (1) to establish a critical care network pressure ulcer prevention group; (2) to establish baseline pressure ulcer prevention practices; (3) to measure, compare and monitor pressure ulcers prevalence; (4) to develop network pressure ulcer prevention standards. The approach used to improve quality included strong critical care nursing leadership to develop a cross-organisational pressure ulcer prevention group and a benchmarking exercise of current practices across a well-established critical care Network in the North of England. The National Safety Thermometer tool was used to measure pressure ulcer prevalence in 23 critical care units, and best available evidence, local consensus and another Critical Care Networks' bundle of interventions were used to develop a local pressure ulcer prevention standards document. The aims of the quality improvement project were achieved. This project was driven by successful leadership and had an agreed common goal. The National Safety Thermometer tool was an innovative approach to measure and compare pressure ulcer prevalence rates at a regional level. A limitation was the exclusion of moisture lesions. The project showed excellent engagement and collaborate working in the quest to prevent pressure ulcers from many critical care nurses with the North of England Critical Care Network. A concise set of Network standards was developed for use in conjunction with local guidelines to enhance pressure ulcer prevention. © 2015 British Association of Critical Care Nurses.

High hunting pressure selects for earlier birth date: Wild boar as a case study

USGS Publications Warehouse

Gamelon, M.; Besnard, A.; Gaillard, J.-M.; Servanty, S.; Baubet, E.; Brandt, S.; Gimenez, O.

2011-01-01

Exploitation by humans affects the size and structure of populations. This has evolutionary and demographic consequences that have typically being studied independent of one another. We here applied a framework recently developed applying quantitative tools from population ecology and selection gradient analysis to quantify the selection on a quantitative trait-birth date-through its association with multiple fitness components. From the long-term monitoring (22 years) of a wild boar (Sus scrofa scrofa) population subject to markedly increasing hunting pressure, we found that birth dates have advanced by up to 12 days throughout the study period. During the period of low hunting pressure, there was no detectable selection. However, during the period of high hunting pressure, the selection gradient linking breeding probability in the first year of life to birth date was negative, supporting current life-history theory predicting selection for early births to reproduce within the first year of life with increasing adult mortality. ?? 2011 The Author(s). Evolution?? 2011 The Society for the Study of Evolution..

Environmental quality alters female costs and benefits of evolving under enforced monogamy.

PubMed

Grazer, Vera M; Demont, Marco; Michalczyk, Łukasz; Gage, Matthew J G; Martin, Oliver Y

2014-02-05

Currently many habitats suffer from quality loss due to environmental change. As a consequence, evolutionary trajectories might shift due to environmental effects and potentially increase extinction risk of resident populations. Nevertheless, environmental variation has rarely been incorporated in studies of sexual selection and sexual conflict, although local environments and individuals' condition undoubtedly influence costs and benefits. Here, we utilise polyandrous and monogamous selection lines of flour beetles, which evolved in presence or absence of sexual selection for 39 generations. We specifically investigated effects of low vs. standard food quality (i.e. stressful vs. benign environments) on reproductive success of cross pairs between beetles from the contrasting female and male selection histories to assess gender effects driving fitness. We found a clear interaction of food quality, male selection history and female selection history. Monogamous females generally performed more poorly than polyandrous counterparts, but reproductive success was shaped by selection history of their mates and environmental quality. When monogamous females were paired with polyandrous males in the standard benign environment, females seemed to incur costs, possibly due to sexual conflict. In contrast, in the novel stressful environment, monogamous females profited from mating with polyandrous males, indicating benefits of sexual selection outweigh costs. Our findings suggest that costs and benefits of sexually selected adaptations in both sexes can be profoundly altered by environmental quality. With regard to understanding possible impacts of environmental change, our results further show that the ecology of mating systems and associated selection pressures should be considered in greater detail.

An Evidence-Based Cue-Selection Guide and Logic Model to Improve Pressure Ulcer Prevention in Long-term Care.

PubMed

Yap, Tracey L; Kennerly, Susan M; Bergstrom, Nancy; Hudak, Sandra L; Horn, Susan D

2016-01-01

Pressure ulcers have consistently resisted prevention efforts in long-term care facilities nationwide. Recent research has described cueing innovations that-when selected according to the assumptions and resources of particular facilities-support best practices of pressure ulcer prevention. This article synthesizes that research into a unified, dynamic logic model to facilitate effective staff implementation of a pressure ulcer prevention program.

Promoting Ethylene Selectivity from CO2 Electroreduction on CuO Supported onto CO2 Capture Materials.

PubMed

Yang, Hui-Juan; Yang, Hong; Hong, Yu-Hao; Zhang, Peng-Yang; Wang, Tao; Chen, Li-Na; Zhang, Feng-Yang; Wu, Qi-Hui; Tian, Na; Zhou, Zhi-You; Sun, Shi-Gang

2018-03-09

Cu is a unique catalyst for CO 2 electroreduction, since it can catalyze CO 2 reduction to a series of hydrocarbons, alcohols, and carboxylic acids. Nevertheless, such Cu catalysts suffer from poor selectivity. High pressure of CO 2 is considered to facilitate the activity and selectivity of CO 2 reduction. Herein, a new strategy is presented for CO 2 reduction with improved C 2 H 4 selectivity on a Cu catalyst by using CO 2 capture materials as the support at ambient pressure. N-doped carbon (N x C) was synthesized through high-temperature carbonization of melamine and l-lysine. We observed that the CO 2 uptake capacity of N x C depends on both the microporous area and the content of pyridinic N species, which can be controlled by the carbonization temperature (600-800 °C). The as-prepared CuO/N x C catalysts exhibit a considerably higher C 2 H 4 faradaic efficiency (36 %) than CuO supported on XC-72 carbon black (19 %), or unsupported CuO (20 %). Moreover, there is a good linear relationship between the C 2 H 4 faradaic efficiency and CO 2 uptake capacity of the supports for CuO. The local high CO 2 concentration near Cu catalysts, created by CO 2 capture materials, was proposed to increase the coverage of CO intermediate, which is favorable for the coupling of two CO units in the formation of C 2 H 4 . This study demonstrates that pairing Cu catalysts with CO 2 capture supports is a promising approach for designing highly effective CO 2 reduction electrocatalysts. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Selective neuronal lapses precede human cognitive lapses following sleep deprivation.

PubMed

Nir, Yuval; Andrillon, Thomas; Marmelshtein, Amit; Suthana, Nanthia; Cirelli, Chiara; Tononi, Giulio; Fried, Itzhak

2017-12-01

Sleep deprivation is a major source of morbidity with widespread health effects, including increased risk of hypertension, diabetes, obesity, heart attack, and stroke. Moreover, sleep deprivation brings about vehicle accidents and medical errors and is therefore an urgent topic of investigation. During sleep deprivation, homeostatic and circadian processes interact to build up sleep pressure, which results in slow behavioral performance (cognitive lapses) typically attributed to attentional thalamic and frontoparietal circuits, but the underlying mechanisms remain unclear. Recently, through study of electroencephalograms (EEGs) in humans and local field potentials (LFPs) in nonhuman primates and rodents it was found that, during sleep deprivation, regional 'sleep-like' slow and theta (slow/theta) waves co-occur with impaired behavioral performance during wakefulness. Here we used intracranial electrodes to record single-neuron activities and LFPs in human neurosurgical patients performing a face/nonface categorization psychomotor vigilance task (PVT) over multiple experimental sessions, including a session after full-night sleep deprivation. We find that, just before cognitive lapses, the selective spiking responses of individual neurons in the medial temporal lobe (MTL) are attenuated, delayed, and lengthened. These 'neuronal lapses' are evident on a trial-by-trial basis when comparing the slowest behavioral PVT reaction times to the fastest. Furthermore, during cognitive lapses, LFPs exhibit a relative local increase in slow/theta activity that is correlated with degraded single-neuron responses and with baseline theta activity. Our results show that cognitive lapses involve local state-dependent changes in neuronal activity already present in the MTL.

Selective epitaxial growth of Ge1-xSnx on Si by using metal-organic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Washizu, Tomoya; Ike, Shinichi; Inuzuka, Yuki; Takeuchi, Wakana; Nakatsuka, Osamu; Zaima, Shigeaki

2017-06-01

Selective epitaxial growth of Ge and Ge1-xSnx layers on Si substrates was performed by using metal-organic chemical vapor deposition (MOCVD) with precursors of tertiary-butyl-germane (t-BGe) and tri-butyl-vinyl-tin (TBVSn). We investigated the effects of growth temperature and total pressure during growth on the selectivity and the crystallinity of the Ge and Ge1-xSnx epitaxial layers. Under low total pressure growth conditions, the dominant mechanism of the selective growth of Ge epitaxial layers is the desorption of the Ge precursors. At a high total pressure case, it is needed to control the surface migration of precursors to realize the selectivity because the desorption of Ge precursors was suppressed. The selectivity of Ge growth was improved by diffusion of the Ge precursors on the SiO2 surfaces when patterned substrates were used at a high total pressure. The selective epitaxial growth of Ge1-xSnx layer was also realized using MOCVD. We found that the Sn precursors less likely to desorb from the SiO2 surfaces than the Ge precursors.

Data services providing by the Ukrainian NODC (MHI NASU)

NASA Astrophysics Data System (ADS)

Eremeev, V.; Godin, E.; Khaliulin, A.; Ingerov, A.; Zhuk, E.

2009-04-01

At modern stage of the World Ocean study information support of investigation based on ad-vanced computer technologies becomes of particular importance. These abstracts are devoted to presentation of several data services developed in the Ukrainian NODC on the base of the Ma-rine Environmental and Information Technologies Department of MHI NASU. The Data Quality Control Service Using experience of international collaboration in the field of data collection and quality check we have developed the quality control (QC) software providing both preliminary(automatic) and expert(manual) data quality check procedures. The current version of the QC software works for the Mediterranean and Black seas and includes the climatic arrays for hydrological and few hydrochemical parameters based on such products as MEDAR/MEDATLAS II, Physical Oceanography of the Black Sea and Climatic Atlas of Oxygen and Hydrogen Sulfide in the Black sea. The data quality check procedure includes metadata control and hydrological and hydrochemical data control. Metadata control provides checking of duplicate cruises and pro-files, date and chronology, ship velocity, station location, sea depth and observation depth. Data QC procedure includes climatic (or range for parameters with small number of observations) data QC, density inversion check for hydrological data and searching for spikes. Using of cli-matic fields and profiles prepared by regional oceanography experts leads to more reliable results of data quality check procedure. The Data Access Services The Ukrainian NODC provides two products for data access - on-line software and data access module for the MHI NASU local net. This software allows select-ing data on rectangle area, on date, on months, on cruises. The result of query is metadata which are presented in the table and the visual presentation of stations on the map. It is possible to see both metadata and data. For this purpose it is necessary to select station in the table of metadata or on the map. There is also an opportunity to export data in ODV format. The product is avail-able on http://www.ocean.nodc.org.ua/DataAccess.php The local net version provides access to the oceanological database of the MHI NASU. The cur-rent version allows selecting data by spatial and temporal limits, depth, values of parameters, quality flags and works for the Mediterranean and Black seas. It provides visualization of meta-data and data, statistics of data selection, data export into several data formats. The Operational Data Management Services The collaborators of the MHI Experimental Branch developed a system of obtaining information on water pressure and temperature, as well as on atmospheric pressure. Sea level observations are also conducted. The obtained data are transferred online. The interface for operation data access was developed. It allows to select parameters (sea level, water temperature, atmospheric pressure, wind and wa-ter pressure) and time interval to see parameter graphics. The product is available on http://www.ocean.nodc.org.ua/Katsively.php . The Climatic products The current version of the Climatic Atlas includes maps on such pa-rameters as temperature, salinity, density, heat storage, dynamic heights, upper boundary of hy-drogen sulfide and lower boundary of oxygen for the Black sea basin. Maps for temperature, sa-linity, density were calculated on 19 standard depths and averaged monthly for depths 0 - 300 m and annually for lower depth values. The climatic maps of upper boundary of hydrogen sulfide and lower boundary of oxygen were averaged by decades from 20 till 90 of the XX century and by seasons. Two versions of climatic atlas viewer - on-line and desktop for presentation of the climatic maps were developed. They provide similar functions of selection and viewing maps by parameter, month and depth and saving maps in various formats. On-line version of atlas is available on http://www.ocean.nodc.org.ua/Main_Atlas.php .

High Selection Pressure Promotes Increase in Cumulative Adaptive Culture

PubMed Central

Vegvari, Carolin; Foley, Robert A.

2014-01-01

The evolution of cumulative adaptive culture has received widespread interest in recent years, especially the factors promoting its occurrence. Current evolutionary models suggest that an increase in population size may lead to an increase in cultural complexity via a higher rate of cultural transmission and innovation. However, relatively little attention has been paid to the role of natural selection in the evolution of cultural complexity. Here we use an agent-based simulation model to demonstrate that high selection pressure in the form of resource pressure promotes the accumulation of adaptive culture in spite of small population sizes and high innovation costs. We argue that the interaction of demography and selection is important, and that neither can be considered in isolation. We predict that an increase in cultural complexity is most likely to occur under conditions of population pressure relative to resource availability. Our model may help to explain why culture change can occur without major environmental change. We suggest that understanding the interaction between shifting selective pressures and demography is essential for explaining the evolution of cultural complexity. PMID:24489724

Focal macromolecule delivery in neuronal tissue using simultaneous pressure ejection and local electroporation

PubMed Central

Barker, Matthew; Billups, Brian; Hamann, Martine

2009-01-01

Electroporation creates transient pores in the plasma membrane to introduce macromolecules within a cell or cell population. Generally, electrical pulses are delivered between two electrodes separated from each other, making electroporation less likely to be localised. We have developed a new device combining local pressure ejection with local electroporation through a double-barrelled glass micropipette to transfer impermeable macromolecules in brain slices or in cultured HEK293 cells. The design achieves better targeting of the site of pressure ejection with that of electroporation. With this technique, we have been able to limit the delivery of propidium iodide or dextran amine within areas of 100–200 μm diameter. We confirm that local electroporation is transient and show that when combined with pressure ejection, it allows local transfection of EGFP plasmids within HEK293 cells or within cerebellar and hippocampal slice cultures. We further show that local electroporation is less damaging when compared to global electroporation using two separate electrodes. Focal delivery of dextran amine dyes within trapezoid body fibres allowed tracing axonal tracts within brainstem slices, enabling the study of identified calyx of Held presynaptic terminals in living brain tissue. This labelling method can be used to target small nuclei in neuronal tissue and is generally applicable to the study of functional synaptic connectivity, or live axonal tracing in a variety of brain areas. PMID:19014970

Why small and medium chemical companies continue to pose severe environmental risks in rural China.

PubMed

He, Guizhen; Zhang, Lei; Mol, Arthur P J; Wang, Tieyu; Lu, Yonglong

2014-02-01

In China, rural chemical SMEs are often believed to still largely operate below the sustainability radar. This paper investigates to what extent and how chemical SMEs are already experiencing pressure to improve their environmental performance, using an in-depth case study in Jasmine County, Hebei province. The results show that local residents had rather low trust in the environmental improvement promises made by the enterprises and the local government, and disagreed with the proposed improvement plans. Although the power of local residents to influence decision making remained limited, the chemical SMEs started to feel increasing pressures to clean up their business, from governments, local communities and civil society, and international value chain stakeholders. Notwithstanding these mounting pressures chemical SME's environmental behavior and performance has not changed radically for the better. The strong economic ties between local county governments and chemical SMEs continue to be a major barrier for stringent environmental regulation. Copyright © 2013 Elsevier Ltd. All rights reserved.

A critical evaluation of crustal dehydration as the cause of an overpressured and weak San Andreas Fault

USGS Publications Warehouse

Fulton, P.M.; Saffer, D.M.; Bekins, B.A.

2009-01-01

Many plate boundary faults, including the San Andreas Fault, appear to slip at unexpectedly low shear stress. One long-standing explanation for a "weak" San Andreas Fault is that fluid release by dehydration reactions during regional metamorphism generates elevated fluid pressures that are localized within the fault, reducing the effective normal stress. We evaluate this hypothesis by calculating realistic fluid production rates for the San Andreas Fault system, and incorporating them into 2-D fluid flow models. Our results show that for a wide range of permeability distributions, fluid sources from crustal dehydration are too small and short-lived to generate, sustain, or localize fluid pressures in the fault sufficient to explain its apparent mechanical weakness. This suggests that alternative mechanisms, possibly acting locally within the fault zone, such as shear compaction or thermal pressurization, may be necessary to explain a weak San Andreas Fault. More generally, our results demonstrate the difficulty of localizing large fluid pressures generated by regional processes within near-vertical fault zones. ?? 2009 Elsevier B.V.

Measurement of pressure-displacement kinetics of hemoglobin in normal breast tissue with near-infrared spectral imaging.

PubMed

Jiang, Shudong; Pogue, Brian W; Laughney, Ashley M; Kogel, Christine A; Paulsen, Keith D

2009-04-01

Applying localized external displacement to the breast surface can change the interstitial fluid pressure such that regional transient microvascular changes occur in oxygenation and vascular volume. Imaging these dynamic responses over time, while different pressures are applied, could provide selective temporal contrast for cancer relative to the surrounding normal breast. In order to investigate this possibility in normal breast tissue, a near-infrared spectral tomography system was developed that can simultaneously acquire data at three wavelengths with a 15 s time resolution per scan. The system was tested first with heterogeneous blood phantoms. Changes in regional blood concentrations were found to be linearly related to recovered mean hemoglobin concentration (Hb(T)) values (R(2)=0.9). In a series of volunteer breast imaging exams, data from 17 asymptomatic subjects were acquired under increasing and decreasing breast compression. Calculations show that a 10 mm displacement applied to the breast results in surface pressures in the range of 0-55 kPa depending on breast density. The recovered human data indicate that Hb(T) was reduced under compression and the normalized change was significantly correlated to the applied pressure with a p value of 0.005. The maximum Hb(T) decreases in breast tissue were associated with body mass index (BMI), which is a surrogate indicator of breast density. No statistically valid correlations were found between the applied pressure and the changes in tissue oxygen saturation (S(t)O(2)) or water percentage (H(2)O) across the range of BMI values studied.

Measurement of pressure-displacement kinetics of hemoglobin in normal breast tissue with near-infrared spectral imaging

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

Jiang, Shudong; Pogue, Brian W.; Laughney, Ashley M.

2009-04-01

Applying localized external displacement to the breast surface can change the interstitial fluid pressure such that regional transient microvascular changes occur in oxygenation and vascular volume. Imaging these dynamic responses over time, while different pressures are applied, could provide selective temporal contrast for cancer relative to the surrounding normal breast. In order to investigate this possibility in normal breast tissue, a near-infrared spectral tomography system was developed that can simultaneously acquire data at three wavelengths with a 15 s time resolution per scan. The system was tested first with heterogeneous blood phantoms. Changes in regional blood concentrations were found tomore » be linearly related to recovered mean hemoglobin concentration (HbT) values (R{sup 2}=0.9). In a series of volunteer breast imaging exams, data from 17 asymptomatic subjects were acquired under increasing and decreasing breast compression. Calculations show that a 10 mm displacement applied to the breast results in surface pressures in the range of 0-55 kPa depending on breast density. The recovered human data indicate that HbT was reduced under compression and the normalized change was significantly correlated to the applied pressure with a p value of 0.005. The maximum HbT decreases in breast tissue were associated with body mass index (BMI), which is a surrogate indicator of breast density. No statistically valid correlations were found between the applied pressure and the changes in tissue oxygen saturation (StO2) or water percentage (H2O) across the range of BMI values studied.« less

Arterial Pressure Gradients during Upright Posture and 30 deg Head Down Tilt

NASA Technical Reports Server (NTRS)

Sanchez, E. R; William, J. M.; Ueno, T.; Ballard, R. E.; Hargens, A. R.; Holton, Emily M. (Technical Monitor)

1997-01-01

Gravity alters local blood pressure within the body so that arterial pressures in the head and foot are lower and higher, respectively, than that at heart level. Furthermore, vascular responses to local alterations of arterial pressure are probably important to maintain orthostatic tolerance upon return to the Earth after space flight. However, it has been difficult to evaluate the body's arterial pressure gradient due to the lack of noninvasive technology. This study was therefore designed to investigate whether finger arterial pressure (FAP), measured noninvasively, follows a normal hydrostatic pressure gradient above and below heart level during upright posture and 30 deg head down tilt (HDT). Seven healthy subjects gave informed consent and were 19 to 52 years old with a height range of 158 to 181 cm. A Finapres device measured arterial pressure at different levels of the body by moving the hand from 36 cm below heart level (BH) to 72 cm above heart level (AH) in upright posture and from 36 cm BH to 48 cm AH during HDT in increments of 12 cm. Mean FAP creased by 85 mmHg transitioning from BH to AH in upright posture, and the pressure gradient calculated from hydrostatic pressure difference (rho(gh)) was 84 mmHg. In HDT, mean FAP decreased by 65 mmHg from BH to AH, and the calculated pressure gradient was also 65 mmHg. There was no significant difference between the measured FAP gradient and the calculated pressure gradient, although a significant (p = 0.023) offset was seen for absolute arterial pressure in upright posture. These results indicate that arterial pressure at various levels can be obtained from the blood pressure at heart level by calculating rho(gh) + an offset. The offset equals the difference between heart level and the site of measurement. In summary, we conclude that local blood pressure gradients can be measured by noninvasive studies of FAP.

Aging-associated sensory neuropathy alters pressure-induced vasodilation in humans.

PubMed

Fromy, Bérengère; Sigaudo-Roussel, Dominique; Gaubert-Dahan, Marie-Line; Rousseau, Pascal; Abraham, Pierre; Benzoni, Daniel; Berrut, Gilles; Saumet, Jean Louis

2010-03-01

Healthy skin is protected from pressure-induced ischemic damage because of the presence of pressure-induced vasodilation (PIV). PIV relies on small sensory nerve fibers and endothelial function. Since aging alters both nervous and vascular functions, we hypothesized that PIV is altered with aging. We compared PIV in non-neuropathic and neuropathic older subjects (60-75 years) with that of young subjects (20-35 years). Laser Doppler flowmetry was used to evaluate the cutaneous responses to local pressure application, acetylcholine, and local heating. Quantitative sensory tests were used to evaluate sensory-nerve-fiber function. The non-neuropathic older subjects had an impaired PIV (12+/-7% increase in blood flow with pressure) compared with young subjects (62+/-4%, P<0.001). In the presence of peripheral neuropathy, the older subjects were totally deprived of PIV, leading to early pressure-induced cutaneous ischemia (-31+/-10%, P<0.001). This inability of the skin to adapt to localized pressure in older subjects is related to the severity of the sensory-fiber dysfunction rather than to endothelial dysfunction, which was comparable between the non-neuropathic (141+/-19% increased blood flow with acetylcholine, P<0.05) and neuropathic older subjects (145+/-28% increase, P<0.05) compared with young subjects (234+/-25% increase).

Predicting Local Dengue Transmission in Guangzhou, China, through the Influence of Imported Cases, Mosquito Density and Climate Variability

PubMed Central

Sang, Shaowei; Yin, Wenwu; Bi, Peng; Zhang, Honglong; Wang, Chenggang; Liu, Xiaobo; Chen, Bin; Yang, Weizhong; Liu, Qiyong

2014-01-01

Introduction Each year there are approximately 390 million dengue infections worldwide. Weather variables have a significant impact on the transmission of Dengue Fever (DF), a mosquito borne viral disease. DF in mainland China is characterized as an imported disease. Hence it is necessary to explore the roles of imported cases, mosquito density and climate variability in dengue transmission in China. The study was to identify the relationship between dengue occurrence and possible risk factors and to develop a predicting model for dengue’s control and prevention purpose. Methodology and Principal Findings Three traditional suburbs and one district with an international airport in Guangzhou city were selected as the study areas. Autocorrelation and cross-correlation analysis were used to perform univariate analysis to identify possible risk factors, with relevant lagged effects, associated with local dengue cases. Principal component analysis (PCA) was applied to extract principal components and PCA score was used to represent the original variables to reduce multi-collinearity. Combining the univariate analysis and prior knowledge, time-series Poisson regression analysis was conducted to quantify the relationship between weather variables, Breteau Index, imported DF cases and the local dengue transmission in Guangzhou, China. The goodness-of-fit of the constructed model was determined by pseudo-R2, Akaike information criterion (AIC) and residual test. There were a total of 707 notified local DF cases from March 2006 to December 2012, with a seasonal distribution from August to November. There were a total of 65 notified imported DF cases from 20 countries, with forty-six cases (70.8%) imported from Southeast Asia. The model showed that local DF cases were positively associated with mosquito density, imported cases, temperature, precipitation, vapour pressure and minimum relative humidity, whilst being negatively associated with air pressure, with different time lags. Conclusions Imported DF cases and mosquito density play a critical role in local DF transmission, together with weather variables. The establishment of an early warning system, using existing surveillance datasets will help to control and prevent dengue in Guangzhou, China. PMID:25019967

Predicting local dengue transmission in Guangzhou, China, through the influence of imported cases, mosquito density and climate variability.

PubMed

Sang, Shaowei; Yin, Wenwu; Bi, Peng; Zhang, Honglong; Wang, Chenggang; Liu, Xiaobo; Chen, Bin; Yang, Weizhong; Liu, Qiyong

2014-01-01

Each year there are approximately 390 million dengue infections worldwide. Weather variables have a significant impact on the transmission of Dengue Fever (DF), a mosquito borne viral disease. DF in mainland China is characterized as an imported disease. Hence it is necessary to explore the roles of imported cases, mosquito density and climate variability in dengue transmission in China. The study was to identify the relationship between dengue occurrence and possible risk factors and to develop a predicting model for dengue's control and prevention purpose. Three traditional suburbs and one district with an international airport in Guangzhou city were selected as the study areas. Autocorrelation and cross-correlation analysis were used to perform univariate analysis to identify possible risk factors, with relevant lagged effects, associated with local dengue cases. Principal component analysis (PCA) was applied to extract principal components and PCA score was used to represent the original variables to reduce multi-collinearity. Combining the univariate analysis and prior knowledge, time-series Poisson regression analysis was conducted to quantify the relationship between weather variables, Breteau Index, imported DF cases and the local dengue transmission in Guangzhou, China. The goodness-of-fit of the constructed model was determined by pseudo-R2, Akaike information criterion (AIC) and residual test. There were a total of 707 notified local DF cases from March 2006 to December 2012, with a seasonal distribution from August to November. There were a total of 65 notified imported DF cases from 20 countries, with forty-six cases (70.8%) imported from Southeast Asia. The model showed that local DF cases were positively associated with mosquito density, imported cases, temperature, precipitation, vapour pressure and minimum relative humidity, whilst being negatively associated with air pressure, with different time lags. Imported DF cases and mosquito density play a critical role in local DF transmission, together with weather variables. The establishment of an early warning system, using existing surveillance datasets will help to control and prevent dengue in Guangzhou, China.

Identification and analysis of evolutionary selection pressures acting at the molecular level in five forkhead subfamilies.

PubMed

Fetterman, Christina D; Rannala, Bruce; Walter, Michael A

2008-09-24

Members of the forkhead gene family act as transcription regulators in biological processes including development and metabolism. The evolution of forkhead genes has not been widely examined and selection pressures at the molecular level influencing subfamily evolution and differentiation have not been explored. Here, in silico methods were used to examine selection pressures acting on the coding sequence of five multi-species FOX protein subfamily clusters; FoxA, FoxD, FoxI, FoxO and FoxP. Application of site models, which estimate overall selection pressures on individual codons throughout the phylogeny, showed that the amino acid changes observed were either neutral or under negative selection. Branch-site models, which allow estimated selection pressures along specified lineages to vary as compared to the remaining phylogeny, identified positive selection along branches leading to the FoxA3 and Protostomia clades in the FoxA cluster and the branch leading to the FoxO3 clade in the FoxO cluster. Residues that may differentiate paralogs were identified in the FoxA and FoxO clusters and residues that differentiate orthologs were identified in the FoxA cluster. Neutral amino acid changes were identified in the forkhead domain of the FoxA, FoxD and FoxP clusters while positive selection was identified in the forkhead domain of the Protostomia lineage of the FoxA cluster. A series of residues under strong negative selection adjacent to the N- and C-termini of the forkhead domain were identified in all clusters analyzed suggesting a new method for refinement of domain boundaries. Extrapolation of domains among cluster members in conjunction with selection pressure information allowed prediction of residue function in the FoxA, FoxO and FoxP clusters and exclusion of known domain function in residues of the FoxA and FoxI clusters. Consideration of selection pressures observed in conjunction with known functional information allowed prediction of residue function and refinement of domain boundaries. Identification of residues that differentiate orthologs and paralogs provided insight into the development and functional consequences of paralogs and forkhead subfamily composition differences among species. Overall we found that after gene duplication of forkhead family members, rapid differentiation and subsequent fixation of amino acid changes through negative selection has occurred.

Probing the electronic and local structural changes across the pressure-induced insulator-to-metal transition in VO2

NASA Astrophysics Data System (ADS)

Marini, C.; Bendele, M.; Joseph, B.; Kantor, I.; Mitrano, M.; Mathon, O.; Baldini, M.; Malavasi, L.; Pascarelli, S.; Postorino, P.

2014-11-01

Local and electronic structures of vanadium in \\text{VO}2 are studied across the high-pressure insulator-to-metal (IMT) transition using V K-edge x-ray absorption spectroscopy. Unlike the temperature-induced IMT, pressure-induced metallization leads to only subtle changes in the V K-edge prepeak structure, indicating a different mechanism involving smaller electronic spectral weight transfer close to the chemical potential. Intriguingly, upon application of the hydrostatic pressure, the electronic structure begins to show substantial changes well before the occurrence of the IMT and the associated structural transition to an anisotropic compression of the monoclinic metallic phase.

Threshold pressure for mechanoluminescence of macrocrystals, microcrystals and nanocrystals of doped zinc sulphide

NASA Astrophysics Data System (ADS)

Chandra, B. P.; Chandra, V. K.; Jha, Piyush; Sonwane, V. D.

2016-06-01

The threshold pressure for elastico-mechanoluminescence (EML) of ZnS:Mn macrocrystals is 20 MPa, and ZnS:Cu,Al macrocrystals do not show ML during elastic deformation. However, the threshold pressure for EML of ZnS:Mn and ZnS:Cu,Cl microcrystals and nanocrystals is nearly 1 MPa. Thus, it seems that high concentration of defects in microcrystalline and nanocrystalline ZnS:Mn and ZnS:Cu,Cl produces disorder and distortion in lattice and changes the local crystal-structure near impurities, and consequently, the enhanced piezoelectric constant of local region produces EML for low value of applied pressure. The threshold pressure for the ML of ZnS:Mn and ZnS:Cu,Al single macrocrystals is higher because such crystals possess comparatively less number of defects near the impurities where the phase-transition is not possible and their ML is caused for high value of stress because the bulk piezoelectric constant is less. Thus, size-dependent threshold pressure for ML supports the origin of EML from piezoelectricity in local region of the crystals. The finding of present investigation may be useful in tailoring phosphors emitting intense EML of different colours.

Plasticity and stress tolerance override local adaptation in the responses of Mediterranean holm oak seedlings to drought and cold.

PubMed

Gimeno, Teresa E; Pías, Beatriz; Lemos-Filho, José P; Valladares, Fernando

2009-01-01

Plant populations of widely distributed species experience a broad range of environmental conditions that can be faced by phenotypic plasticity or ecotypic differentiation and local adaptation. The strategy chosen will determine a population's ability to respond to climate change. To explore this, we grew Quercus ilex (L.) seedlings from acorns collected at six selected populations from climatically contrasting localities and evaluated their response to drought and late season cold events. Maximum photosynthetic rate (A(max)), instantaneous water use efficiency (iWUE), and thermal tolerance to freeze and heat (estimated from chlorophyll fluorescence versus temperature curves) were measured in 5-month-old seedlings in control (no stress), drought (water-stressed), and cold (low suboptimal temperature) conditions. The observed responses were similar for the six populations: drought decreased A(max) and increased iWUE, and cold reduced A(max) and iWUE. All the seedlings maintained photosynthetic activity under adverse conditions (drought and cold), and rapidly increased their iWUE by closing stomata when exposed to drought. Heat and freeze tolerances were similarly high for seedlings from all the populations, and they were significantly increased by drought and cold, respectively; and were positively related to each other. Differences in seedling performance across populations were primarily induced by maternal effects mediated by seed size and to a lesser extent by idiosyncratic physiologic responses to drought and low temperatures. Tolerance to multiple stresses together with the capacity to physiologically acclimate to heat waves and cold snaps may allow Q. ilex to cope with the increasingly stressful conditions imposed by climate change. Lack of evidence of physiologic seedling adaptation to local climate may reflect opposing selection pressures to complex, multidimensional environmental conditions operating within the distribution range of this species.

Multigrid calculation of internal flows in complex geometries

NASA Technical Reports Server (NTRS)

Smith, K. M.; Vanka, S. P.

1992-01-01

The development, validation, and application of a general purpose multigrid solution algorithm and computer program for the computation of elliptic flows in complex geometries is presented. This computer program combines several desirable features including a curvilinear coordinate system, collocated arrangement of the variables, and Full Multi-Grid/Full Approximation Scheme (FMG/FAS). Provisions are made for the inclusion of embedded obstacles and baffles inside the flow domain. The momentum and continuity equations are solved in a decoupled manner and a pressure corrective equation is used to update the pressures such that the fluxes at the cell faces satisfy local mass continuity. Despite the computational overhead required in the restriction and prolongation phases of the multigrid cycling, the superior convergence results in reduced overall CPU time. The numerical scheme and selected results of several validation flows are presented. Finally, the procedure is applied to study the flowfield in a side-inlet dump combustor and twin jet impingement from a simulated aircraft fuselage.

Electronic-structure calculations of praseodymium metal by means of modified density-functional theory

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

Svane, A.; Trygg, J.; Johansson, B.

1997-09-01

Electronic-structure calculations of elemental praseodymium are presented. Several approximations are used to describe the Pr f electrons. It is found that the low-pressure, trivalent phase is well described using either the self-interaction corrected (SIC) local-spin-density (LSD) approximation or the generalized-gradient approximation (GGA) with spin and orbital polarization (OP). In the SIC-LSD approach the Pr f electrons are treated explicitly as localized with a localization energy given by the self-interaction of the f orbital. In the GGA+OP scheme the f-electron localization is described by the onset of spin and orbital polarization, the energetics of which is described by spin-moment formation energymore » and a term proportional to the total orbital moment, L{sub z}{sup 2}. The high-pressure phase is well described with the f electrons treated as band electrons, in either the LSD or the GGA approximations, of which the latter describes more accurately the experimental equation of state. The calculated pressure of the transition from localized to delocalized behavior is 280 kbar in the SIC-LSD approximation and 156 kbar in the GGA+OP approach, both comparing favorably with the experimentally observed transition pressure of 210 kbar. {copyright} {ital 1997} {ital The American Physical Society}« less

Enhanced densification under shock compression in porous silicon

DOE PAGES

Lane, J. Matthew; Thompson, Aidan Patrick; Vogler, Tracy

2014-10-27

Under shock compression, most porous materials exhibit lower densities for a given pressure than that of a full-dense sample of the same material. However, some porous materials exhibit an anomalous, or enhanced, densification under shock compression. The mechanism driving this behavior was not completely determined. We present evidence from atomistic simulation that pure silicon belongs to this anomalous class of materials and demonstrate the associated mechanisms responsible for the effect in porous silicon. Atomistic response indicates that local shear strain in the neighborhood of collapsing pores catalyzes a local solid-solid phase transformation even when bulk pressures are below the thermodynamicmore » phase transformation pressure. This metastable, local, and partial, solid-solid phase transformation, which accounts for the enhanced densification in silicon, is driven by the local stress state near the void, not equilibrium thermodynamics. This mechanism may also explain the phenomenon in other covalently bonded materials.« less

The effect of kerosene injection on ignition probability of local ignition in a scramjet combustor

NASA Astrophysics Data System (ADS)

Bao, Heng; Zhou, Jin; Pan, Yu

2017-03-01

The spark ignition of kerosene is investigated in a scramjet combustor with a flight condition of Ma 4, 17 km. Based plentiful of experimental data, the ignition probabilities of the local ignition have been acquired for different injection setups. The ignition probability distributions show that the injection pressure and injection location have a distinct effect on spark ignition. The injection pressure has both upper and lower limit for local ignition. Generally, the larger mass flow rate will reduce the ignition probability. The ignition position also affects the ignition near the lower pressure limit. The reason is supposed to be the cavity swallow effect on upstream jet spray near the leading edge, which will make the cavity fuel rich. The corner recirculation zone near the front wall of the cavity plays a significant role in the stabilization of local flame.

Alongshore Momentum Balance Over Shoreface-Connected Ridges, Fire Island, NY

NASA Astrophysics Data System (ADS)

Ofsthun, C.; Wu, X.; Voulgaris, G.; Warner, J. C.

2016-12-01

he momentum balance of alongshore flows over straight, uniform shelfs has been analyzed extensively over the last few decades. More recently, the effect of coastline curvature and how this might alter the relative significance of the momentum terms has received additional attention. In this contribution, the alongshore momentum over shelves with straight coastline, but non-uniform bathymetry is examined. Hydrodynamic and hydrographic data collected by the US Geological Survey (Fire Island Coastal Change project) on the inner shelf of Fire Island, NY over a region of shore-face connected ridges (SFCRs) are used to describe wind-induced circulation and the terms of the alongshore momentum balance equation. Analysis of the data revealed a predominantly alongshore circulation, under westward wind forcing, with localized offshore (onshore) current veering over the ridge crests (troughs). Momentum balance analysis hinted that local acceleration, advective acceleration, and bottom stress are balanced by wind stress and regional (>100 km) pressure gradient force. In addition, a numerical model using an idealized SFCR bathymetry, forced by our observed winds, was employed to compare the momentum balance relationships identified by the data and those under steady-state conditions published earlier (Warner et al., 2014). A synthesis of the numerical and experimental data revealed that the true pressure gradient force results from the sum of local pressure gradient force, which maintains a Bernoulli-like relationship with alongshore advective acceleration, and regional pressure gradient force, which maintains a strong, negative relationship with wind stress. The differences between steady-state and realistic conditions is mainly on the contributions of regional scale pressure gradients that develop under realistic conditions, and the reduced contribution of local scale pressure gradients which develop best under steady-state conditions. Our analysis indicates that current veering over ridge crests, a consistent occurrence, is a combination of a cross-shore gradient in the inconsistent relationship between local advective acceleration and pressure gradient and frictional-torque with the latter being the dominant mechanism under realistic forcing.

Chemical recovery process using break up steam control to prevent smelt explosions

DOEpatents

Kohl, Arthur L.; Stewart, Albert E.

1988-08-02

An improvement in a chemical recovery process in which a hot liquid smelt is introduced into a dissolving tank containing a pool of green liquor. The improvement comprises preventing smelt explosions in the dissolving tank by maintaining a first selected superatmospheric pressure in the tank during normal operation of the furnace; sensing the pressure in the tank; and further impinging a high velocity stream of steam upon the stream of smelt whenever the pressure in the tank decreases below a second selected superatmospheric pressure which is lower than said first pressure.

SISGR - Hydrogen Caged in Carbon-Exploration of Novel Carbon-Hydrogen Interactions

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

Lueking, Angela; Badding, John; Crespi, Vinent

Hydrogen trapped in a carbon cage, captured through repulsive interactions, is a novel concept in hydrogen storage. Trapping hydrogen via repulsive interactions borrows an idea from macroscale hydrogen storage (i.e. compressed gas storage tanks) and reapplies these concepts on the nanoscale in specially designed molecular containers. Under extreme conditions of pressure, hydrogen solubility in carbon materials is expected to increase and carbon is expected to restructure to minimize volume via a mixed sp2/sp3 hydrogenated state. Thermodynamics dictate that pre-formed C-H structures will rearrange with increased pressure, yet the final carbon-hydrogen interactions may be dependent upon the mechanism by which hydrogenmore » is introduced. Gas “trapping” is meant to denote gas present in a solid in a high density, adsorbed-like state, when the external pressure is much less than that necessary to provide a comparable fluid density. Trapping thus denotes a kinetically metastable state rather than thermodynamic equilibrium. This project probed mechanochemical means to polymerize select hydrocarbons in the presence of gases, in an attempt to form localized carbon cages that trap gases via repulsive interactions. Aromatic, polyaromatic, and hydroaromatic molecules expected to undergo cyclo-addition reactions were polymerized at high (~GPa) pressures to form extended hydrogenated amorphous carbon networks. Notably, aromatics with a pre-existing internal free volume (such as Triptycene) appeared to retain an internal porosity upon application of pressure. However, a high photoluminescence background after polymerization precluded in situ identification of trapped gases. No spectroscopic evidence was found after depressurization that would be indicative of pockets of trapped gases in a localized high-pressure environment. Control studies suggested this measurement may be insensitive to gases at low pressure. Similarly, no spectral fingerprint was found for gas-imbued spherical carbon nanoshells, even after chemical “capping” of the gas-imbued nanoshells to limit gas diffusivity. Subsequently, spectral probes of gas vibrational modes adsorbed in various carbon nanostructures (including activated carbons, single-wall carbon nanotubes, polymers of intrinsic microporosity (PIMs), and UV-irradiated PIMs with decreased pore size) were found only at high pressure. The vibrational mode of the adsorbed film became perturbed in high density films, and the perturbation was sensitive to surface functional groups, pore size, and pore dimension. Experimental results were corroborated with first-principle modeling using density functional theory. Development of semi-empirical correlations that relate the spectral features to pore dimension, geometry, and chemical potential of the adsorbed film are on-going.« less

Electronic scanning pressure measuring system and transducer package

NASA Technical Reports Server (NTRS)

Coe, C. F. (Inventor); Parra, G. T.

1984-01-01

An electronic scanning pressure system that includes a plurality of pressure transducers is examined. A means obtains an electrical signal indicative of a pressure measurement from each of the plurality of pressure transducers. A multiplexing means is connected for selectivity supplying inputs from the plurality of pressure transducers to the signal obtaining means. A data bus connects the plurality of pressure transducers to the multiplexing means. A latch circuit is connected to supply control inputs to the multiplexing means. An address bus is connected to supply an address signal of a selected one of the plurality of pressure transducers to the latch circuit. In operation, each of the pressure transducers is successively scanned by the multiplexing means in response to address signals supplied on the address bus to the latch circuit.

Adaptive evolution in locomotor performance: How selective pressures and functional relationships produce diversity.

PubMed

Scales, Jeffrey A; Butler, Marguerite A

2016-01-01

Despite the complexity of nature, most comparative studies of phenotypic evolution consider selective pressures in isolation. When competing pressures operate on the same system, it is commonly expected that trade-offs will occur that will limit the evolution of phenotypic diversity, however, it is possible that interactions among selective pressures may promote diversity instead. We explored the evolution of locomotor performance in lizards in relation to possible selective pressures using the Ornstein-Uhlenbeck process. Here, we show that a combination of selection based on foraging mode and predator escape is required to explain variation in performance phenotypes. Surprisingly, habitat use contributed little explanatory power. We find that it is possible to evolve very different abilities in performance which were previously thought to be tightly correlated, supporting a growing literature that explores the many-to-one mapping of morphological design. Although we generally find the expected trade-off between maximal exertion and speed, this relationship surprisingly disappears when species experience selection for both performance types. We conclude that functional integration need not limit adaptive potential, and that an integrative approach considering multiple major influences on a phenotype allows a more complete understanding of adaptation and the evolution of diversity. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Interplay of magnetism and superconductivity in the compressed Fe-ladder compound BaFe 2 Se 3

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

Ying, Jianjun; Lei, Hechang; Petrovic, Cedomir

High pressure resistance, susceptibility, and Fe K β x-ray emission spectroscopy measurements were performed on Fe-ladder compound BaFe 2 Se 3 . Pressure-induced superconductivity was observed which is similar to the previously reported superconductivity in the BaFe 2 S 3 samples. The slope of local magnetic moment versus pressure shows an anomaly across the insulator-metal transition pressure in the BaFe 2 Se 3 samples. The local magnetic moment is continuously decreasing with increasing pressure, and the superconductivity appears only when the local magnetic moment value is comparable to the one in the iron-pnictide superconductors. Our results indicate that the compressedmore » BaFe 2 C h 3 ( C h = S , Se) is a new family of iron-based superconductors. Despite the crystal structures completely different from the known iron-based superconducting materials, the magnetism in this Fe-ladder material plays a critical role in superconductivity. This behavior is similar to the other members of iron-based superconducting materials.« less

Effect of simulated hyperemia on the flow field in a mildly atherosclerotic coronary artery casting of man

NASA Technical Reports Server (NTRS)

Cho, Y. I.; Back, L. H.; Crawford, D. W.

1985-01-01

Changes in an arterial flow field due to mild atherosclerosis were determined using a main coronary artery casting with a maximum obstruction of about 50 percent by area. Local pressure changes were measured using six pressure tap holes along the wall of the casting. The test-fluid was a 33 percent sugar-water solution of approximately the same viscosity as human blood. Flow visualization results were obtained by injecting blue-dye through the pressure tap holes. Measurement of local pressure demonstrated a significant Reynolds number effect. At Reynolds numbers of 80-710, a local pressure rise was observed downstream of the mild atherosclerotic constriction due to momentum changes. The Reynolds number necessary for flow separation in the divergent region of the coronary casting was about 330. The experimental results can be used to obtain a quantitative relation between coronary morphology and the fluid dynamic consequences of mild diffuse disease under conditions of maximum cardiac demand i.e., higher coronary flow rates and Reynolds numbers associated with space and atmospheric flight.

Postural vascular response in human skin: passive and active reactions to alteration of transmural pressure.

PubMed

Jepsen, H; Gaehtgens, P

1993-09-01

Laser-Doppler (LD) fluxmetry was performed in the palmar finger skin of healthy subjects to study the mechanisms contributing to the postural vascular response. Local transmural pressure in the skin blood vessels of the region studied was altered for 1 min in two experimental series either by passive movement of the arm to different vertical hand positions relative to heart level or by application of external pressure (-120-180 mmHg) to the finger. Heart and respiratory rate, arterial blood pressure, and LD flux in the contralateral finger (kept at heart level) were measured. The measurements suggest a compound reaction of local (myogenic) and systemic (neurogenic) mechanisms: the local regulatory component appears as a graded active vascular response elicited by passive vessel distension or compression. A systemic component, associated with a single deep inspiration, is frequently observed during the actual movement of the arm. In addition, prolonged holding of the test hand in a given vertical position also elicits a delayed vascular response in the control hand at heart level, which may be generated by volume receptors in the intrathoracic low-pressure system.

Microstructure Evolution and Selective Corrosion Resistance in Underwater Multi-pass 2101 Duplex Stainless Steel Welding Joints

NASA Astrophysics Data System (ADS)

Hu, Yu; Shi, Yonghua; Shen, Xiaoqin; Wang, Zhongmin

2018-05-01

A recently developed promising material, 2101 lean duplex stainless steel, represents an alternative to 304 austenite stainless steel. In this work, multi-pass 2101 weld joints were fabricated using the flux-cored arc welding method in a hyperbaric chamber. The pressure varied from 0 to 0.75 MPa. The evolution of the welding process and microstructure was investigated. γ 2 formation in the reheated zones of the WM and HAZ was not uniform. The closer the reheated zone is to the subsequent heat source, the greater the γ 2 formation in the reheated zone. Sufficient primary austenite transformation inhibited Cr2N precipitation and the subsequent intragranular γ 2 formation in the reheated weld passes of the 0.45 MPa weld metal. The localized corrosion resistance of each zone of the 0.45 MPa DSS joint was measured using non-destructive double-loop electrochemical potentiokinetic reactivation tests. The localized corrosion was induced by γ 2 and Cr2N. The root region of the 0.45 MPa weld metal underwent two subsequent welding thermal cycles, which induced increased γ 2 formation and lower resistance to corrosion because of the decreased pitting resistance value of γ 2. The correlation between microstructure evolution and the distribution of selective corrosion was determined.

Evidence of maternal effects on temperature preference in side-blotched lizards: implications for evolutionary response to climate change

PubMed Central

Paranjpe, Dhanashree A; Bastiaans, Elizabeth; Patten, Amy; Cooper, Robert D; Sinervo, Barry

2013-01-01

Natural populations respond to selection pressures like increasing local temperatures in many ways, including plasticity and adaptation. To predict the response of ectotherms like lizards to local temperature increase, it is essential to estimate phenotypic variation in and determine the heritability of temperature-related traits like average field body temperature (Tb) and preferred temperature (Tp). We measured Tp of Uta stansburiana in a laboratory thermal gradient and assessed the contribution of sex, reproductive status and throat color genotype to phenotypic variation in Tb of adult lizards. Females had higher Tp than males. However, they temporarily preferred lower temperature when gravid than when nongravid. Using a nested half-sib design for genetic crosses in the laboratory, we estimated relative contributions of additive genetic variation and maternal effects to Tp of hatchlings. Our results show that maternal effects, but not additive genetic variation, influence Tp of hatchlings in U. stansburiana. Maternal Tp and the presence or absence of blue throat color alleles significantly influenced Tp of hatchlings. We discuss ecological and evolutionary consequences of these maternal effects in the context of rapid climate change and natural selection that we measure on progeny survival to maturity as a function of maternal Tp. PMID:23919144

Admixture Analysis of Spontaneous Hepatitis C Virus Clearance in Individuals of African-Descent

PubMed Central

Wojcik, Genevieve L.; Thio, Chloe L.; Kao, WH Linda; Latanich, Rachel; Goedert, James J.; Mehta, Shruti H.; Kirk, Gregory D.; Peters, Marion G.; Cox, Andrea L.; Kim, Arthur Y.; Chung, Raymond T.; Thomas, David L.; Duggal, Priya

2015-01-01

Hepatitis C virus (HCV) infects an estimated 3% of the global population with the majority of individuals (75–85%) failing to clear the virus without treatment, leading to chronic liver disease. Individuals of African-descent have lower rates of clearance compared to individuals of European-descent and this is not fully explained by social and environmental factors. This suggests that differences in genetic background may contribute to this difference in clinical outcome following HCV infection. Using 473 individuals and 792,721 SNPs from a genome-wide association study (GWAS), we estimated local African ancestry across the genome. Using admixture mapping and logistic regression we identified two regions of interest associated with spontaneous clearance of HCV (15q24, 20p12). A genome-wide significant variant was identified on chromosome 15 at the imputed SNP, rs55817928 (P=6.18×10−8) between the genes SCAPER and RCN. Each additional copy of the African ancestral C allele is associated with 2.4 times the odds of spontaneous clearance. Conditional analysis using this SNP in the logistic regression model explained one-third of the local ancestry association. Additionally, signals of selection in this area suggest positive selection due to some ancestral pathogen or environmental pressure in African, but not in European populations. PMID:24622687

Evidence of maternal effects on temperature preference in side-blotched lizards: implications for evolutionary response to climate change.

PubMed

Paranjpe, Dhanashree A; Bastiaans, Elizabeth; Patten, Amy; Cooper, Robert D; Sinervo, Barry

2013-07-01

Natural populations respond to selection pressures like increasing local temperatures in many ways, including plasticity and adaptation. To predict the response of ectotherms like lizards to local temperature increase, it is essential to estimate phenotypic variation in and determine the heritability of temperature-related traits like average field body temperature (T b) and preferred temperature (T p). We measured T p of Uta stansburiana in a laboratory thermal gradient and assessed the contribution of sex, reproductive status and throat color genotype to phenotypic variation in T b of adult lizards. Females had higher T p than males. However, they temporarily preferred lower temperature when gravid than when nongravid. Using a nested half-sib design for genetic crosses in the laboratory, we estimated relative contributions of additive genetic variation and maternal effects to T p of hatchlings. Our results show that maternal effects, but not additive genetic variation, influence T p of hatchlings in U. stansburiana. Maternal T p and the presence or absence of blue throat color alleles significantly influenced T p of hatchlings. We discuss ecological and evolutionary consequences of these maternal effects in the context of rapid climate change and natural selection that we measure on progeny survival to maturity as a function of maternal T p.

Hampering Effect of Cholesterol on the Permeation of Reactive Oxygen Species through Phospholipids Bilayer: Possible Explanation for Plasma Cancer Selectivity

NASA Astrophysics Data System (ADS)

van der Paal, Jonas; Verheyen, Claudia; Neyts, Erik C.; Bogaerts, Annemie

2017-01-01

In recent years, the ability of cold atmospheric pressure plasmas (CAPS) to selectively induce cell death in cancer cells has been widely established. This selectivity has been assigned to the reactive oxygen and nitrogen species (RONS) created in CAPs. To provide new insights in the search for an explanation for the observed selectivity, we calculate the transfer free energy of multiple ROS across membranes containing a varying amount of cholesterol. The cholesterol fraction is investigated as a selectivity parameter because membranes of cancer cells are known to contain lower fractions of cholesterol compared to healthy cells. We find that cholesterol has a significant effect on the permeation of reactive species across a membrane. Indeed, depending on the specific reactive species, an increasing cholesterol fraction can lead to (i) an increase of the transfer free energy barrier height and width, (ii) the formation of a local free energy minimum in the center of the membrane and (iii) the creation of extra free energy barriers due to the bulky sterol rings. In the context of plasma oncology, these observations suggest that the increased ingress of RONS in cancer cells can be explained by the decreased cholesterol fraction of their cell membrane.

CO2 hydrogenation to methanol on supported Au catalysts under moderate reaction conditions: support and particle size effects.

PubMed

Hartadi, Yeusy; Widmann, Daniel; Behm, R Jürgen

2015-02-01

The potential of metal oxide supported Au catalysts for the formation of methanol from CO2 and H2 under conditions favorable for decentralized and local conversion, which could be concepts for chemical energy storage, was investigated. Significant differences in the catalytic activity and selectivity of Au/Al2 O3 , Au/TiO2 , AuZnO, and Au/ZrO2 catalysts for methanol formation under moderate reaction conditions at a pressure of 5 bar and temperatures between 220 and 240 °C demonstrate pronounced support effects. A high selectivity (>50 %) for methanol formation was obtained only for Au/ZnO. Furthermore, measurements on Au/ZnO samples with different Au particle sizes reveal distinct Au particle size effects: although the activity increases strongly with the decreasing particle size, the selectivity decreases. The consequences of these findings for the reaction mechanism and for the potential of Au/ZnO catalysts for chemical energy storage and a "green" methanol technology are discussed. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Conformational Fluctuations in G-Protein-Coupled Receptors

NASA Astrophysics Data System (ADS)

Brown, Michael F.

2014-03-01

G-protein-coupled receptors (GPCRs) comprise almost 50% of pharmaceutical drug targets, where rhodopsin is an important prototype and occurs naturally in a lipid membrane. Rhodopsin photoactivation entails 11-cis to all-trans isomerization of the retinal cofactor, yielding an equilibrium between inactive Meta-I and active Meta-II states. Two important questions are: (1) Is rhodopsin is a simple two-state switch? Or (2) does isomerization of retinal unlock an activated conformational ensemble? For an ensemble-based activation mechanism (EAM) a role for conformational fluctuations is clearly indicated. Solid-state NMR data together with theoretical molecular dynamics (MD) simulations detect increased local mobility of retinal after light activation. Resultant changes in local dynamics of the cofactor initiate large-scale fluctuations of transmembrane helices that expose recognition sites for the signal-transducing G-protein. Time-resolved FTIR studies and electronic spectroscopy further show the conformational ensemble is strongly biased by the membrane lipid composition, as well as pH and osmotic pressure. A new flexible surface model (FSM) describes how the curvature stress field of the membrane governs the energetics of active rhodopsin, due to the spontaneous monolayer curvature of the lipids. Furthermore, influences of osmotic pressure dictate that a large number of bulk water molecules are implicated in rhodopsin activation. Around 60 bulk water molecules activate rhodopsin, which is much larger than the number of structural waters seen in X-ray crystallography, or inferred from studies of bulk hydrostatic pressure. Conformational selection and promoting vibrational motions of rhodopsin lead to activation of the G-protein (transducin). Our biophysical data give a paradigm shift in understanding GPCR activation. The new view is: dynamics and conformational fluctuations involve an ensemble of substates that activate the cognate G-protein in the amplified visual response.

Localized Flow of Frictional Or Creeping Materials In A Lower Flat Thrust To Ramp Transition

NASA Astrophysics Data System (ADS)

Maillot, B.; Leroy, Y.

The passage of rock through zones of localized shear deformation in the form of back- thrusts or kink planes is common in fold and thrust belts. The stationary flow through these two types of hinges is examined for the particular case of a lower flat to ramp transition of a fault-bend fold. The simple shear transformation resulting in strain lo- calization is studied both analytically and numerically. The overall equilibrium of the hanging wall, accounting for friction over the ramp, constrains the shear and normal forces acting on the hinge boundaries. For frictional materials, the localization oc- curs in the form of a velocity discontinuity, defining the backthrust, with a dip which is shown not to bissect ramp angle nor to conserve the thrust nappe thickness, if a criteria based on a minimization of the total dissipation is considered. For creeping materials, the strain localization as a kink plane is shown to require a destabilizing deformation mechanism, selected here to be flexural slip. The rotation of the stress tensor due to the gradient in pressure, the thicknening and thinning of the creeping material, the rate and amount of flexural slip through the hinge are analyzed to define potential tectonic markers.

Local weather is associated with rates of online searches for musculoskeletal pain symptoms.

PubMed

Telfer, Scott; Obradovich, Nick

2017-01-01

Weather conditions are commonly believed to influence musculoskeletal pain, however the evidence for this is mixed. This study aimed to examine the relationship between local meteorological conditions and online search trends for terms related to knee pain, hip pain, and arthritis. Five years of relative online search volumes for these terms were obtained for the 50 most populous cities in the contiguous United States, along with corresponding local weather data for temperature, relative humidity, barometric pressure, and precipitation. Methods from the climate econometrics literature were used to assess the casual impact of these meteorological variables on the relative volumes of searches for pain. For temperatures between -5°C and 30°C, search volumes for hip pain increased by 12 index points, and knee pain increased by 18 index points. Precipitation had a negative effect on search volumes for these terms. At temperatures >30°C, search volumes for arthritis related pain decreased by 7 index points. These patterns were not seen for pain searches unrelated to the musculoskeletal system. In summary, selected local weather conditions are significantly associated with online search volumes for specific musculoskeletal pain symptoms. We believe the predominate driver for this to be the relative changes in physical activity levels associated with meteorological conditions.

An approach to constrained aerodynamic design with application to airfoils

NASA Technical Reports Server (NTRS)

Campbell, Richard L.

1992-01-01

An approach was developed for incorporating flow and geometric constraints into the Direct Iterative Surface Curvature (DISC) design method. In this approach, an initial target pressure distribution is developed using a set of control points. The chordwise locations and pressure levels of these points are initially estimated either from empirical relationships and observed characteristics of pressure distributions for a given class of airfoils or by fitting the points to an existing pressure distribution. These values are then automatically adjusted during the design process to satisfy the flow and geometric constraints. The flow constraints currently available are lift, wave drag, pitching moment, pressure gradient, and local pressure levels. The geometric constraint options include maximum thickness, local thickness, leading-edge radius, and a 'glove' constraint involving inner and outer bounding surfaces. This design method was also extended to include the successive constraint release (SCR) approach to constrained minimization.

Processes underpinning development and maintenance of diversity in rice in West Africa: evidence from combining morphological and molecular markers.

PubMed

Mokuwa, Alfred; Nuijten, Edwin; Okry, Florent; Teeken, Béla; Maat, Harro; Richards, Paul; Struik, Paul C

2014-01-01

We assessed the interplay of artificial and natural selection in rice adaptation in low-input farming systems in West Africa. Using 20 morphological traits and 176 molecular markers, 182 farmer varieties of rice (Oryza spp.) from 6 West African countries were characterized. Principal component analysis showed that the four botanical groups (Oryza sativa ssp. indica, O. sativa ssp. japonica, O. glaberrima, and interspecific farmer hybrids) exhibited different patterns of morphological diversity. Regarding O. glaberrima, morphological and molecular data were in greater conformity than for the other botanical groups. A clear difference in morphological features was observed between O. glaberrima rices from the Togo hills and those from the Upper Guinea Coast, and among O. glaberrima rices from the Upper Guinea Coast. For the other three groups such clear patterns were not observed. We argue that this is because genetic diversity is shaped by different environmental and socio-cultural selection pressures. For O. glaberrima, recent socio-cultural selection pressures seemed to restrict genetic diversity while this was not observed for the other botanical groups. We also show that O. glaberrima still plays an important role in the selection practices of farmers and resulting variety development pathways. This is particularly apparent in the case of interspecific farmer hybrids where a relationship was found between pericarp colour, panicle attitude and genetic diversity. Farmer varieties are the product of long and complex trajectories of selection governed by local human agency. In effect, rice varieties have emerged that are adapted to West African farming conditions through genotype × environment × society interactions. The diversity farmers maintain in their rice varieties is understood to be part of a risk-spreading strategy that also facilitates successful and often serendipitous variety innovations. We advocate, therefore, that farmers and farmer varieties should be more effectively involved in crop development.

Processes Underpinning Development and Maintenance of Diversity in Rice in West Africa: Evidence from Combining Morphological and Molecular Markers

PubMed Central

Maat, Harro; Richards, Paul; Struik, Paul C.

2014-01-01

We assessed the interplay of artificial and natural selection in rice adaptation in low-input farming systems in West Africa. Using 20 morphological traits and 176 molecular markers, 182 farmer varieties of rice (Oryza spp.) from 6 West African countries were characterized. Principal component analysis showed that the four botanical groups (Oryza sativa ssp. indica, O. sativa ssp. japonica, O. glaberrima, and interspecific farmer hybrids) exhibited different patterns of morphological diversity. Regarding O. glaberrima, morphological and molecular data were in greater conformity than for the other botanical groups. A clear difference in morphological features was observed between O. glaberrima rices from the Togo hills and those from the Upper Guinea Coast, and among O. glaberrima rices from the Upper Guinea Coast. For the other three groups such clear patterns were not observed. We argue that this is because genetic diversity is shaped by different environmental and socio-cultural selection pressures. For O. glaberrima, recent socio-cultural selection pressures seemed to restrict genetic diversity while this was not observed for the other botanical groups. We also show that O. glaberrima still plays an important role in the selection practices of farmers and resulting variety development pathways. This is particularly apparent in the case of interspecific farmer hybrids where a relationship was found between pericarp colour, panicle attitude and genetic diversity. Farmer varieties are the product of long and complex trajectories of selection governed by local human agency. In effect, rice varieties have emerged that are adapted to West African farming conditions through genotype × environment × society interactions. The diversity farmers maintain in their rice varieties is understood to be part of a risk-spreading strategy that also facilitates successful and often serendipitous variety innovations. We advocate, therefore, that farmers and farmer varieties should be more effectively involved in crop development. PMID:24465809

Evolutionary divergence in sexual signals: Insights from within and among barn swallow populations

NASA Astrophysics Data System (ADS)

Wilkins, Matthew Reed

A wealth of studies across diverse animal groups indicate the importance of sexual selection in shaping phenotypes within and across breeding populations. In recent decades, much research has focused on how divergent sexual selection pressures among populations may lead to speciation. For my first dissertation chapter, I performed a literature review on the causes and consequences of evolutionary divergence in acoustic signals and developed the acoustic window conceptual framework for understanding the contributions of selection, genetic drift, and evolutionary constraint to signal divergence. Further, I found that sexual selection explains acoustic differences between recently diverged populations of the best-studied taxa. However, the relative contributions of ecological selection, sexual selection, and drift to acoustic divergence have not typically been considered within the same study systems. The remainder of my dissertation used the Northern Hemisphere-distributed barn swallow ( Hirundo rustica) species complex as a model system to study sender-receiver dynamics, intra- and intersexual selection pressures, and visual and acoustic signal interactions at the local scale, and signal divergence across populations at the global scale. From song recordings taken across 19 sampling sites, spanning five of six described subspecies, I demonstrated considerable conservation in song structure. However, temporal traits were highly divergent across subspecies, and in particular, the speed of the terminal trill of songs. In a detailed study of the multimodal communication system of the barn swallow (including visual and acoustic traits), I demonstrated that males and females use different types of signals to mediate competition and mate choice. One of the only exceptions to this rule was trill rate, which was also implicated in song divergence across populations. In order to test the function of trill rate in communication, I performed a two-year playback study within the North American subspecies, H. r. erythrogaster. Contrary to expectations, males did not have stronger responses to faster trilling (high performance) simulated intruders. Instead, resident males had stronger responses to the high performance stimulus only when the intruder was also darker than the resident. Collectively, my dissertation offers novel insight into the evolutionary dynamics of complex sexual signaling at multiple spatial scales.

Temperature gradient affects differentiation of gene expression and SNP allele frequencies in the dominant Lake Baikal zooplankton species.

PubMed

Bowman, Larry L; Kondrateva, Elizaveta S; Timofeyev, Maxim A; Yampolsky, Lev Y

2018-06-01

Local adaptation and phenotypic plasticity are main mechanisms of organisms' resilience in changing environments. Both are affected by gene flow and are expected to be weak in zooplankton populations inhabiting large continuous water bodies and strongly affected by currents. Lake Baikal, the deepest and one of the coldest lakes on Earth, experienced epilimnion temperature increase during the last 100 years, exposing Baikal's zooplankton to novel selective pressures. We obtained a partial transcriptome of Epischura baikalensis (Copepoda: Calanoida), the dominant component of Baikal's zooplankton, and estimated SNP allele frequencies and transcript abundances in samples from regions of Baikal that differ in multiyear average surface temperatures. The strongest signal in both SNP and transcript abundance differentiation is the SW-NE gradient along the 600+ km long axis of the lake, suggesting isolation by distance. SNP differentiation is stronger for nonsynonymous than synonymous SNPs and is paralleled by differential survival during a laboratory exposure to increased temperature, indicating directional selection operating on the temperature gradient. Transcript abundance, generally collinear with the SNP differentiation, shows samples from the warmest, less deep location clustering together with the southernmost samples. Differential expression is more frequent among transcripts orthologous to candidate thermal response genes previously identified in model arthropods, including genes encoding cytoskeleton proteins, heat-shock proteins, proteases, enzymes of central energy metabolism, lipid and antioxidant pathways. We conclude that the pivotal endemic zooplankton species in Lake Baikal exists under temperature-mediated selection and possesses both genetic variation and plasticity to respond to novel temperature-related environmental pressures. © 2018 John Wiley & Sons Ltd.

Local support against gravity in magnetoturbulent fluids

NASA Astrophysics Data System (ADS)

Schmidt, W.; Collins, D. C.; Kritsuk, A. G.

2013-06-01

Comparisons of the integrated thermal pressure support of gas against its gravitational potential energy lead to critical mass scales for gravitational instability such as the Jeans and the Bonnor-Ebert masses, which play an important role in the analysis of many physical systems, including the heuristics of numerical simulations. In a strict theoretical sense, however, neither the Jeans nor the Bonnor-Ebert mass is meaningful when applied locally to substructure in a self-gravitating turbulent medium. For this reason, we investigate the local support by thermal pressure, turbulence and magnetic fields against gravitational compression through an approach that is independent of these concepts. At the centre of our approach is the dynamical equation for the divergence of the velocity field. We carry out a statistical analysis of the source terms of the local compression rate (the negative time derivative of the divergence) for simulations of forced self-gravitating turbulence in periodic boxes with zero, weak and moderately strong mean magnetic fields (measured by the averages of the magnetic and thermal pressures). We also consider the amplification of the magnetic field energy by shear and by compression. Thereby, we are able to demonstrate that the support against gravity is dominated by thermal pressure fluctuations, although magnetic pressure also yields a significant contribution. The net effect of turbulence in the highly supersonic regime, however, is to enhance compression rather than supporting overdense gas even if the vorticity is very high. This is incommensurate with the support of the highly dynamical substructures in magnetoturbulent fluids being determined by local virial equilibria of volume energies without surface stresses.

Measurement of carotid blood pressure and local pulse wave velocity changes during cuff induced hyperemia.

PubMed

Nabeel, P M; Karthik, Srinivasa; Joseph, Jayaraj; Sivaprakasam, Mohanasankar

2017-07-01

We present a prototype design of dual element photoplethysmograph (PPG) probe along with associated measurement system for carotid local pulse wave velocity (PWV) evaluation in a non-invasive and continuous manner. The PPG probe consists of two identical sensing modules placed 23 mm apart. Simultaneously measured blood pulse waveforms from these arterial sites were processed and the pulse transit time delay was resolved using the developed application-specific software. The ability of developed PPG probe and associated measurement system to detect acute changes in carotid local PWV due to blood pressure (BP) variations was experimentally validated by an in-vivo study. Intra-subject carotid BP elevation was achieved by an upper arm cuff based occlusion, which offered a controlled way of local PWV escalation. The elevated carotid BP values were also recorded by a calibrated pressure tonometer prior to the study, and was used as a reference. A significant increment (1.0 - 2.6 m/s) in local PWV was observed and was proportional to the BP increment induced by the occlusive reactive hyperemia. Study results demonstrated the feasibility of real-time signal acquisition and reliable local PWV evaluation under normal and elevated BP conditions using the developed measurement system.

Effective dialogue: enhanced public engagement as a legitimising tool for municipal waste management decision-making.

PubMed

Garnett, Kenisha; Cooper, Tim

2014-12-01

The complexity of municipal waste management decision-making has increased in recent years, accompanied by growing scrutiny from stakeholders, including local communities. This complexity reflects a socio-technical framing of the risks and social impacts associated with selecting technologies and sites for waste treatment and disposal facilities. Consequently there is growing pressure on local authorities for stakeholders (including communities) to be given an early opportunity to shape local waste policy in order to encourage swift planning, development and acceptance of the technologies needed to meet statutory targets to divert waste from landfill. This paper presents findings from a research project that explored the use of analytical-deliberative processes as a legitimising tool for waste management decision-making. Adopting a mixed methods approach, the study revealed that communicating the practical benefits of more inclusive forms of engagement is proving difficult even though planning and policy delays are hindering development and implementation of waste management infrastructure. Adopting analytical-deliberative processes at a more strategic level will require local authorities and practitioners to demonstrate how expert-citizen deliberations may foster progress in resolving controversial issues, through change in individuals, communities and institutions. The findings suggest that a significant shift in culture will be necessary for local authorities to realise the potential of more inclusive decision processes. This calls for political actors and civic society to collaborate in institutionalising public involvement in both strategic and local planning structures. Copyright © 2014 Elsevier Ltd. All rights reserved.

Model atmospheres for cool stars. [varying chemical composition

NASA Technical Reports Server (NTRS)

Johnson, H. R.

1974-01-01

This report contains an extensive series of model atmospheres for cool stars having a wide range in chemical composition. Model atmospheres (temperature, pressure, density, etc.) are tabulated, along with emergent energy flux distributions, limb darkening, and information on convection for selected models. The models are calculated under the usual assumptions of hydrostatic equilibrium, constancy of total energy flux (including transport both by radiation and convection) and local thermodynamic equilibrium. Some molecular and atomic line opacity is accounted for as a straight mean. While cool star atmospheres are regimes of complicated physical conditions, and these atmospheres are necessarily approximate, they should be useful for a number of kinds of spectral and atmospheric analysis.

Thermodynamic Properties of Low-Density {}^{132}Xe Gas in the Temperature Range 165-275 K

NASA Astrophysics Data System (ADS)

Akour, Abdulrahman

2018-01-01

The method of static fluctuation approximation was used to calculate selected thermodynamic properties (internal energy, entropy, energy capacity, and pressure) for xenon in a particularly low-temperature range (165-270 K) under different conditions. This integrated microscopic study started from an initial basic assumption as the main input. The basic assumption in this method was to replace the local field operator with its mean value, then numerically solve a closed set of nonlinear equations using an iterative method, considering the Hartree-Fock B2-type dispersion potential as the most appropriate potential for xenon. The results are in very good agreement with those of an ideal gas.

Clinical Issues-November 2017.

PubMed

Johnstone, Esther M

2017-11-01

Heating, ventilation, and air-conditioning (HVAC) systems in the OR Key words: airborne contaminants, HVAC system, air pressure, air quality, temperature and humidity. Air changes and positive pressure Key words: air changes, positive pressure airflow, unidirectional airflow, outdoor air, recirculated air. Product selection Key word: product evaluation, product selection, selection committee. Entry into practice Key words: associate degree in nursing, bachelor of science in nursing, entry-level position, advanced education, BSN-prepared RNs. Mentoring in perioperative nursing Key words: mentor, novice, practice improvement, nursing workforce. Copyright © 2017 AORN, Inc. Published by Elsevier Inc. All rights reserved.

Use of hydrostatic pressure for modulation of protein chemical modification and enzymatic selectivity.

PubMed

Makarov, Alexey A; Helmy, Roy; Joyce, Leo; Reibarkh, Mikhail; Maust, Mathew; Ren, Sumei; Mergelsberg, Ingrid; Welch, Christopher J

2016-05-11

Using hydrostatic pressure to induce protein conformational changes can be a powerful tool for altering the availability of protein reactive sites and for changing the selectivity of enzymatic reactions. Using a pressure apparatus, it has been demonstrated that hydrostatic pressure can be used to modulate the reactivity of lysine residues of the protein ubiquitin with a water-soluble amine-specific homobifunctional coupling agent. Fewer reactive lysine residues were observed when the reaction was carried out under elevated pressure of 3 kbar, consistent with a pressure-induced conformational change of ubiquitin that results in fewer exposed lysine residues. Additionally, modulation of the stereoselectivity of an enzymatic transamination reaction was observed at elevated hydrostatic pressure. In one case, the minor diasteromeric product formed at atmospheric pressure became the major product at elevated pressure. Such pressure-induced alterations of protein reactivity may provide an important new tool for enzymatic reactions and the chemical modification of proteins.

Methods and Systems for Configuring Sensor Acquisition Based on Pressure Steps

NASA Technical Reports Server (NTRS)

DeDonato, Mathew (Inventor)

2015-01-01

Technologies are provided for underwater measurements. A system includes an underwater vessels including: a plurality of sensors disposed thereon for measuring underwater properties; and a programmable controller configured to selectively activate the plurality of sensors based at least in part on underwater pressure. A user may program at what pressure ranges certain sensors are activated to measure selected properties, and may also program the ascent/descent rate of the underwater vessel, which is correlated with the underwater pressure.

Electron band structure of the high pressure cubic phase of AlH3

NASA Astrophysics Data System (ADS)

Shi, Hongliang; Zarifi, Niliffar; Yim, Wai-Leung; Tse, J. S.

2012-07-01

The electronic band structure of the cubic Pm3n phase of AlH3 stable above 100 GPa is examined with semi-local, Tran-Blaha modified Becke-Johnson local density approximation (TB-mBJLDA), screened hybrid density functionals and GW methods. The shift of the conduction band to higher energy with increasing pressure is predicted by all methods. However, there are significant differences in detail band structure. In the pressure range from 90 to160 GPa, semi-local, hybrid functional and TB-mBJLDA calculations predicted that AlH3 is a poor metal. In comparison, GW calculations show a gap opening at 160 GPa and AlH3 becomes a small gap semi-conductor. From the trends of the calculated band shifts, it can be concluded that the favourable conditions leading to the nesting of Fermi surfaces predicted by semi-local calculation have disappeared if the exchange term is included. The results highlight the importance of the correction to the exchange energy on the band structure of hydrogen dominant dense metal hydrides at high pressure hydrides and may help to rationalize the absence of superconductivity in AlH3 from experimental measurements.

Twenty-five thousand years of fluctuating selection on leopard complex spotting and congenital night blindness in horses.

PubMed

Ludwig, Arne; Reissmann, Monika; Benecke, Norbert; Bellone, Rebecca; Sandoval-Castellanos, Edson; Cieslak, Michael; Fortes, Gloria G; Morales-Muñiz, Arturo; Hofreiter, Michael; Pruvost, Melanie

2015-01-19

Leopard complex spotting is inherited by the incompletely dominant locus, LP, which also causes congenital stationary night blindness in homozygous horses. We investigated an associated single nucleotide polymorphism in the TRPM1 gene in 96 archaeological bones from 31 localities from Late Pleistocene (approx. 17 000 YBP) to medieval times. The first genetic evidence of LP spotting in Europe dates back to the Pleistocene. We tested for temporal changes in the LP associated allele frequency and estimated coefficients of selection by means of approximate Bayesian computation analyses. Our results show that at least some of the observed frequency changes are congruent with shifts in artificial selection pressure for the leopard complex spotting phenotype. In early domestic horses from Kirklareli-Kanligecit (Turkey) dating to 2700-2200 BC, a remarkably high number of leopard spotted horses (six of 10 individuals) was detected including one adult homozygote. However, LP seems to have largely disappeared during the late Bronze Age, suggesting selection against this phenotype in early domestic horses. During the Iron Age, LP reappeared, probably by reintroduction into the domestic gene pool from wild animals. This picture of alternating selective regimes might explain how genetic diversity was maintained in domestic animals despite selection for specific traits at different times. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

Evolution of two-dimensional plasma parameters in the plane of the wafer during the E- to H- and H- to E-mode transition in an inductively coupled plasma

NASA Astrophysics Data System (ADS)

Park, Il-Seo; Kim, Kyung-Hyun; Kim, Tae-Woo; Kim, Kwan-Youg; Moon, Ho-Jun; Chung, Chin-Wook

2018-05-01

The evolution of plasma parameters during the transition from E- to H- and from H- to E-mode is measured at the wafer level two-dimensionally at low and high pressures. The plasma parameters, such as electron density and electron temperature, are obtained through a floating harmonic sideband method. During the E- to H-mode transition, while the electron kinetics remains in the non-local regime at low pressure, the electron kinetics is changed from the non-local to the local regime at high pressure. The two-dimensional profiles of the electron density at two different pressures have similar convex shape despite different electron kinetics. However, in the case of the electron temperature, at high pressure, the profiles of the electron temperature are changed from flat to convex shape. These results can be understood by the diffusion of the plasma to the wafer-level probe. Moreover, between the transition of E to H and reverse H to E, hysteresis is observed even at the wafer level. The hysteresis is clearly shown at high pressure compared to low pressure. This can be explained by a variation of collisional energy loss including effects of electron energy distribution function (bi-Maxwellian, Maxwellian, Druyvesteyn distribution) on the rate constant and multistep ionization of excited state atoms. During the E- to H-mode transition, Maxwellization is caused by increased electron‑electron collisions, which reduces the collisional energy loss at high pressure (Druyvesteyn distribution) and increases it at low pressure (bi-Maxwellian distribution). Thus, the hysteresis is intensified at high pressure because the reduced collisional energy loss leads to higher ionization efficiency.

Quantifying Selective Pressures Driving Bacterial Evolution Using Lineage Analysis

NASA Astrophysics Data System (ADS)

Lambert, Guillaume; Kussell, Edo

2015-01-01

Organisms use a variety of strategies to adapt to their environments and maximize long-term growth potential, but quantitative characterization of the benefits conferred by the use of such strategies, as well as their impact on the whole population's rate of growth, remains challenging. Here, we use a path-integral framework that describes how selection acts on lineages—i.e., the life histories of individuals and their ancestors—to demonstrate that lineage-based measurements can be used to quantify the selective pressures acting on a population. We apply this analysis to Escherichia coli bacteria exposed to cyclical treatments of carbenicillin, an antibiotic that interferes with cell-wall synthesis and affects cells in an age-dependent manner. While the extensive characterization of the life history of thousands of cells is necessary to accurately extract the age-dependent selective pressures caused by carbenicillin, the same measurement can be recapitulated using lineage-based statistics of a single surviving cell. Population-wide evolutionary pressures can be extracted from the properties of the surviving lineages within a population, providing an alternative and efficient procedure to quantify the evolutionary forces acting on a population. Importantly, this approach is not limited to age-dependent selection, and the framework can be generalized to detect signatures of other trait-specific selection using lineage-based measurements. Our results establish a powerful way to study the evolutionary dynamics of life under selection and may be broadly useful in elucidating selective pressures driving the emergence of antibiotic resistance and the evolution of survival strategies in biological systems.

Quantifying selective pressures driving bacterial evolution using lineage analysis

PubMed Central

Lambert, Guillaume; Kussell, Edo

2015-01-01

Organisms use a variety of strategies to adapt to their environments and maximize long-term growth potential, but quantitative characterization of the benefits conferred by the use of such strategies, as well as their impact on the whole population’s rate of growth, remains challenging. Here, we use a path-integral framework that describes how selection acts on lineages –i.e. the life-histories of individuals and their ancestors– to demonstrate that lineage-based measurements can be used to quantify the selective pressures acting on a population. We apply this analysis to E. coli bacteria exposed to cyclical treatments of carbenicillin, an antibiotic that interferes with cell-wall synthesis and affects cells in an age-dependent manner. While the extensive characterization of the life-history of thousands of cells is necessary to accurately extract the age-dependent selective pressures caused by carbenicillin, the same measurement can be recapitulated using lineage-based statistics of a single surviving cell. Population-wide evolutionary pressures can be extracted from the properties of the surviving lineages within a population, providing an alternative and efficient procedure to quantify the evolutionary forces acting on a population. Importantly, this approach is not limited to age-dependent selection, and the framework can be generalized to detect signatures of other trait-specific selection using lineage-based measurements. Our results establish a powerful way to study the evolutionary dynamics of life under selection, and may be broadly useful in elucidating selective pressures driving the emergence of antibiotic resistance and the evolution of survival strategies in biological systems. PMID:26213639

Molecular evolution of the enzymes involved in the sphingolipid metabolism of Leishmania: selection pressure in relation to functional divergence and conservation.

PubMed

Mandlik, Vineetha; Shinde, Sonali; Singh, Shailza

2014-06-21

Selection pressure governs the relative mutability and the conservedness of a protein across the protein family. Biomolecules (DNA, RNA and proteins) continuously evolve under the effect of evolutionary pressure that arises as a consequence of the host parasite interaction. IPCS (Inositol phosphorylceramide synthase), SPL (Sphingosine-1-P lyase) and SPT (Serine palmitoyl transferase) represent three important enzymes involved in the sphingolipid metabolism of Leishmania. These enzymes are responsible for maintaining the viability and infectivity of the parasite and have been classified as druggable targets in the parasite metabolome. The present work relates to the role of selection pressure deciding functional conservedness and divergence of the drug targets. IPCS and SPL protein families appear to diverge from the SPT family. The three protein families were largely under the influence of purifying selection and were moderately conserved baring two residues in the IPCS protein which were under the influence of positive selection. To further explore the selection pressure at the codon level, codon usage bias indices were calculated to analyze genes for their synonymous codon usage pattern. IPCS gene exhibited slightly lower codon bias as compared to SPL and SPT protein families. Evolutionary tracing of the proposed drug targets has been done with a viewpoint that the amino-acids lining the drug binding pocket should have a lower evolvability. Sites under positive selection (HIS20 and CYS30 of IPCS) should be avoided during devising strategies for inhibitor design.

Decoding intravesical pressure from local field potentials in rat lumbosacral spinal cord

NASA Astrophysics Data System (ADS)

Im, Changkyun; Park, Hae Yong; Koh, Chin Su; Ryu, Sang Baek; Seo, In Seok; Kim, Yong Jung; Kim, Kyung Hwan; Shin, Hyung-Cheul

2016-10-01

Chronic monitoring of intravesical pressure is required to detect the onset of intravesical hypertension and the progression of a more severe condition. Recent reports demonstrate the bladder state can be monitored from the spiking activity of the dorsal root ganglia or lumbosacral spinal cord. However, one of the most serious challenges for these methods is the difficulty of sustained spike signal acquisition due to the high-electrode-location-sensitivity of spikes or neuro-degeneration. Alternatively, it has been demonstrated that local field potential recordings are less affected by encapsulation reactions or electrode location changes. Here, we hypothesized that local field potential (LFP) from the lumbosacral dorsal horn may provide information concerning the intravesical pressure. LFP and spike activities were simultaneously recorded from the lumbosacral spinal cord of anesthetized rats during bladder filling. The results show that the LFP activities carry significant information about intravesical pressure along with spiking activities. Importantly, the intravesical pressure is decoded from the power in high-frequency bands (83.9-256 Hz) with a substantial performance similar to that of the spike train decoding. These findings demonstrate that high-frequency LFP activity can be an alternative intravesical pressure monitoring signal, which could lead to a proper closed loop system for urinary control.

Nb K-edge x-ray absorption investigation of the pressure induced amorphization in A-site deficient double perovskite La1/3NbO3.

PubMed

Marini, C; Noked, O; Kantor, I; Joseph, B; Mathon, O; Shuker, R; Kennedy, B J; Pascarelli, S; Sterer, E

2016-02-03

Nb K-edge x-ray absorption spectroscopy is utilized to investigate the changes in the local structure of the A-site deficient double perovskite La1/3NbO3 which undergoes a pressure induced irreversible amorphization. EXAFS results show that with increasing pressure up to 7.5 GPa, the average Nb-O bond distance decreases in agreement with the expected compression and tilting of the NbO6 octahedra. On the contrary, above 7.5 GPa, the average Nb-O bond distance show a tendency to increase. Significant changes in the Nb K-edge XANES spectrum with evident low energy shift of the pre-peak and the absorption edge is found to happen in La1/3NbO3 above 6.3 GPa. These changes evidence a gradual reduction of the Nb cations from Nb(5+) towards Nb(4+) above 6.3 GPa. Such a valence change accompanied by the elongation of the average Nb-O bond distances in the octahedra, introduces repulsion forces between non-bonding adjacent oxygen anions in the unoccupied A-sites. Above a critical pressure, the Nb reduction mechanism can no longer be sustained by the changing local structure and amorphization occurs, apparently due to the build-up of local strain. EXAFS and XANES results indicate two distinct pressure regimes having different local and electronic response in the La1/3NbO3 system before the occurence of the pressure induced amorphization at  ∼14.5 GPa.

Global versus local mechanisms of temperature sensing in ion channels.

PubMed

Arrigoni, Cristina; Minor, Daniel L

2018-05-01

Ion channels turn diverse types of inputs, ranging from neurotransmitters to physical forces, into electrical signals. Channel responses to ligands generally rely on binding to discrete sensor domains that are coupled to the portion of the channel responsible for ion permeation. By contrast, sensing physical cues such as voltage, pressure, and temperature arises from more varied mechanisms. Voltage is commonly sensed by a local, domain-based strategy, whereas the predominant paradigm for pressure sensing employs a global response in channel structure to membrane tension changes. Temperature sensing has been the most challenging response to understand and whether discrete sensor domains exist for pressure and temperature has been the subject of much investigation and debate. Recent exciting advances have uncovered discrete sensor modules for pressure and temperature in force-sensitive and thermal-sensitive ion channels, respectively. In particular, characterization of bacterial voltage-gated sodium channel (BacNa V ) thermal responses has identified a coiled-coil thermosensor that controls channel function through a temperature-dependent unfolding event. This coiled-coil thermosensor blueprint recurs in other temperature sensitive ion channels and thermosensitive proteins. Together with the identification of ion channel pressure sensing domains, these examples demonstrate that "local" domain-based solutions for sensing force and temperature exist and highlight the diversity of both global and local strategies that channels use to sense physical inputs. The modular nature of these newly discovered physical signal sensors provides opportunities to engineer novel pressure-sensitive and thermosensitive proteins and raises new questions about how such modular sensors may have evolved and empowered ion channel pores with new sensibilities.

Method and apparatus for the selective separation of gaseous coal gasification products by pressure swing adsorption

DOEpatents

Ghate, Madhav R.; Yang, Ralph T.

1987-01-01

Bulk separation of the gaseous components of multi-component gases provided by the gasification of coal including hydrogen, carbon monoxide, methane, and acid gases (carbon dioxide plus hydrogen sulfide) are selectively adsorbed by a pressure swing adsorption technique using activated carbon, zeolite or a combination thereof as the adsorbent. By charging a column containing the adsorbent with a gas mixture and pressurizing the column to a pressure sufficient to cause the adsorption of the gases and then reducing the partial pressure of the contents of the column, the gases are selectively and sequentially desorbed. Hydrogen, the least absorbable gas of the gaseous mixture, is the first gas to be desorbed and is removed from the column in a co-current direction followed by the carbon monoxide, hydrogen and methane. With the pressure in the column reduced to about atmospheric pressure the column is evacuated in a countercurrent direction to remove the acid gases from the column. The present invention is particularly advantageous as a producer of high parity hydrogen from gaseous products of coal gasification and as an acid gas scrubber.

Population dynamics of Aedes aegypti from a dengue hyperendemic urban setting in Colombia.

PubMed

Ocampo, Clara B; Wesson, Dawn M

2004-10-01

This study evaluated if the Aedes aegypti population in the city of Cali, Colombia was composed of genetically distinct local populations with different levels of insecticide resistance and dengue vector competence. Insecticide resistance was assayed biochemically and was associated with varying levels of mixed-function oxidases and non-specific esterases. The genes encoding those enzymes were under selective pressure from insecticides used to suppress Ae. aegypti populations. Vector competence showed heterogeneity among the vector populations ranging from 19% to 60%. Population genetic analysis of random amplified polymorphic DNA-polymerase chain reaction products, expressed as genetic distance, Wright's F(st), and migration rate (Nm), demonstrated moderate genetic differentiation among Ae. aegypti from four sites (F(st) = 0.085). The results from all characteristics evaluated in the study demonstrated spatial and temporal variation between Ae. aegypti populations. At any specific time, the local populations of Ae. aegypti were genetically differentiated and unique with respect to insecticide resistance and vector competence. Both characteristics changed independently.

Anatomy and Pathophysiology of Spinal Cord Injury Associated With Regional Anesthesia and Pain Medicine: 2015 Update.

PubMed

Neal, Joseph M; Kopp, Sandra L; Pasternak, Jeffrey J; Lanier, William L; Rathmell, James P

2015-01-01

In March 2012, the American Society of Regional Anesthesia and Pain Medicine convened its second Practice Advisory on Neurological Complications in Regional Anesthesia and Pain Medicine. This update is based on the proceedings of that conference and relevant information published since its conclusion. This article updates previously described information on the pathophysiology of spinal cord injury and adds new material on spinal stenosis, blood pressure control during neuraxial blockade, neuraxial injury subsequent to transforaminal procedures, cauda equina syndrome/local anesthetic neurotoxicity/arachnoiditis, and performing regional anesthetic or pain medicine procedures in patients concomitantly receiving general anesthesia or deep sedation. Recommendations are based on extensive review of research on humans or employing animal models, case reports, pathophysiology research, and expert opinion. The pathophysiology of spinal cord injury associated with regional anesthetic techniques is reviewed in depth, including that related to mechanical trauma from direct needle/catheter injury or mass lesions, spinal cord ischemia or vascular injury from direct needle/catheter trauma, and neurotoxicity from local anesthetics, adjuvants, or antiseptics. Specific recommendations are offered that may reduce the likelihood of spinal cord injury associated with regional anesthetic or interventional pain medicine techniques. The practice advisory's recommendations may, in select cases, reduce the likelihood of injury. However, many of the described injuries are neither predictable nor preventable based on our current state of knowledge. Since publication of initial recommendations in 2008, new information has enhanced our understanding of 5 specific entities: spinal stenosis, blood pressure control during neuraxial anesthesia, neuraxial injury subsequent to transforaminal techniques, cauda equina syndrome/local anesthetic neurotoxicity/arachnoiditis, and performing regional anesthetic or pain procedures in patients concomitantly receiving general anesthesia or deep sedation.

Source-receptor relationships for PM2.5 during typical pollution episodes in the Pearl River Delta city cluster, China.

PubMed

Liu, Yiming; Hong, Yingying; Fan, Qi; Wang, Xuemei; Chan, Pakwai; Chen, Xiaoyang; Lai, Anqi; Wang, Mingjie; Chen, Xunlai

2017-10-15

Located in the Southern China monsoon region, pollution days in Pearl River Delta (PRD) were classified into "Western type", "Central type" or "Eastern type", with a relative percentage of 67%, 24% and 9%, respectively. Using this classification system, three typical pollution events were selected for numerical simulations using the WRF-Chem model. The source sensitivity method for anthropogenic emissions of PM 2.5 and its precursors was applied to identify the source-receptor relationships for PM 2.5 among 9 cities in PRD. For "Western type" case, the PRD region was under control of a high-pressure system with easterly prevailing winds. The PM 2.5 concentrations in the western PRD region were higher than those in the eastern region, with emissions from cities in the eastern PRD region having higher contributions. Within the PRD's urban cluster, PM 2.5 in Huizhou, Dongguan and Shenzhen was mainly derived from local emissions, whereas the PM 2.5 in the other cities was primarily derived from external transport. For "Eastern type" case, the PRD was influenced by Typhoon Soulik with westerly prevailing winds. Emissions from cities in the western PRD region had the highest impacts on the overall PM 2.5 concentration. PM 2.5 in Jiangmen and Foshan was primarily derived from local emissions. Regarding "Central type" case, the PRD region was under control of a uniform pressure field with low wind speed. PM 2.5 concentrations of each city were primarily caused by local emissions. Overall, wind flows played a significant role in the transport and spatial distribution of PM 2.5 across the PRD region. Ideally, local governments would be wise to establish joint prevention and control measures to reduce regional atmospheric pollution, especially for "Western type" pollution. Copyright © 2017 Elsevier B.V. All rights reserved.

Changes in the Plasticity of HIV-1 Nef RNA during the Evolution of the North American Epidemic

PubMed Central

Manzourolajdad, Amirhossein; Gonzalez, Mileidy; Spouge, John L.

2016-01-01

Because of a high mutation rate, HIV exists as a viral swarm of many sequence variants evolving under various selective pressures from the human immune system. Although the Nef gene codes for the most immunogenic of HIV accessory proteins, which alone makes it of great interest to HIV research, it also encodes an RNA structure, whose contribution to HIV virulence has been largely unexplored. Nef RNA helps HIV escape RNA interference (RNAi) through nucleotide changes and alternative folding. This study examines Historic and Modern Datasets of patient HIV-1 Nef sequences during the evolution of the North American epidemic for local changes in RNA plasticity. By definition, RNA plasticity refers to an RNA molecule’s ability to take alternative folds (i.e., alternative conformations). Our most important finding is that an evolutionarily conserved region of the HIV-1 Nef gene, which we denote by R2, recently underwent a statistically significant increase in its RNA plasticity. Thus, our results indicate that Modern Nef R2 typically accommodates an alternative fold more readily than Historic Nef R2. Moreover, the increase in RNA plasticity resides mostly in synonymous nucleotide changes, which cannot be a response to selective pressures on the Nef protein. R2 may therefore be of interest in the development of antiviral RNAi therapies. PMID:27685447

Structure reactivity relationships during N2O hydrogenation over Au-Ag alloys: A study by field emission techniques

NASA Astrophysics Data System (ADS)

Jacobs, Luc; Barroo, Cédric; Gilis, Natalia; Lambeets, Sten V.; Genty, Eric; Visart de Bocarmé, Thierry

2018-03-01

To make available atomic oxygen at the surface of a catalyst is the key step for oxidation reactions on Au-based catalysts. In this context, Au-Ag alloys catalysts exhibit promising properties for selective oxidation reactions of alcohols: low temperature activity and high selectivity. The presence of O(ads) and its effects on the catalytic reactivity is studied via the N2O dissociative adsorption and subsequent hydrogenation. Field emission techniques are particularly suited to study this reaction: Field Ion Microscopy (FIM) and Field Emission Microscopy (FEM) enable to image the extremity of sharp metallic tips, the size and morphology of which are close to those of one single catalytic particle. The reaction dynamics is studied in the 300-320 K temperature range and at a pressure of 3.5 × 10-3 Pa. The main results are a strong structure/reactivity relationship during N2O + H2 reaction over Au-8.8 at.%Ag model catalysts. Comparison of high-resolution FIM images of the clean sample and FEM images during reaction shows a sensitivity of the reaction to the local structure of the facets, independently of the used partial pressures of both N2O and H2. This suggests a localised dissociative adsorption step for N2O and H2 with the formation of a reactive interface around the {210} facets.

Characterization of peripheral and central sensitization after dorsal root ganglion intervention in patients with unilateral lumbosacral radicular pain: a prospective pilot study.

PubMed

Mehta, V; Snidvongs, S; Ghai, B; Langford, R; Wodehouse, T

2017-06-01

Quantitative sensory testing (QST) has been used to predict the outcome of epidural steroid injections in lumbosacral radicular pain and has the potential to be an important tool in the selection of appropriate treatment (such as epidural steroid injections vs surgery) for patients with chronic radicular pain. In addition, QST assists in identification of the pain pathways of peripheral and central sensitization in selected groups of patients. Twenty-three patients were given dorsal root ganglion (DRG) infiltration with local anaesthesia and steroid ('DRG block'), and those who demonstrated at least 50% pain relief were offered pulsed radiofrequency (PRF) to the DRG. Questionnaires and QST scores were measured before the DRG blocks and at 1 week and 3 months after their procedure. Those who received PRF also answered questionnaires and underwent QST measurements at 1 week and 3 months after their procedure. There was a significant increase in pressure pain threshold scores after DRG blocks. A reduced conditioned pain modulation response was seen before DRG, which increased after the procedure. Ten out of 23 patients underwent PRF to the DRG, and an increase in pressure pain threshold scores after PRF was observed. The conditioned pain modulation response was maintained in this group and increased after PRF. The study demonstrates that patients with unilateral radicular low back pain who receive dorsal root ganglion interventions show changes in pressure pain thresholds and conditioned pain modulation that are consistent with a 'normalization' of peripheral and central sensitization. © The Author 2017. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com

Attentional selection of relative SF mediates global versus local processing: evidence from EEG.

PubMed

Flevaris, Anastasia V; Bentin, Shlomo; Robertson, Lynn C

2011-06-13

Previous research on functional hemispheric differences in visual processing has associated global perception with low spatial frequency (LSF) processing biases of the right hemisphere (RH) and local perception with high spatial frequency (HSF) processing biases of the left hemisphere (LH). The Double Filtering by Frequency (DFF) theory expanded this hypothesis by proposing that visual attention selects and is directed to relatively LSFs by the RH and relatively HSFs by the LH, suggesting a direct causal relationship between SF selection and global versus local perception. We tested this idea in the current experiment by comparing activity in the EEG recorded at posterior right and posterior left hemisphere sites while participants' attention was directed to global or local levels of processing after selection of relatively LSFs versus HSFs in a previous stimulus. Hemispheric asymmetry in the alpha band (8-12 Hz) during preparation for global versus local processing was modulated by the selected SF. In contrast, preparatory activity associated with selection of SF was not modulated by the previously attended level (global/local). These results support the DFF theory that top-down attentional selection of SF mediates global and local processing.

Mortality and recurrence rate after pressure ulcer operation for elderly long-term bedridden patients.

PubMed

Kuwahara, Masamitsu; Tada, Hideyuki; Mashiba, Kumi; Yurugi, Satoshi; Iioka, Hiroshi; Niitsuma, Katsunori; Yasuda, Yukiko

2005-06-01

We operated on 16 sacral pressure ulcers in elderly and long-term residential patients who were immobile as a result of cerebral vascular disease. The mean age of patients was 76 years. Eight ulcers were treated with local fascial flaps and 8 by simple closure. The follow-up period was from 1 to 4 years. Recurrence and mortality rates were examined retrospectively. In the 16 patients, recurrence occurred in 37.5%, and 43.8% died without recurrence. The recurrence rate was 37.5% for local fascial flaps and 37.5% for simple closure. Overall mortality was 68.8% in the follow-up period. Because postoperative death was common, we should not only focus on reducing local pressure but also pay attention to any underlying disease. Because of this high mortality rate, the least invasive procedure possible should be used. Because the recurrence rate of simple closure was the same as for local fascial flaps, simple closure should be considered as a reconstructive method.

Along fault friction and fluid pressure effects on the spatial distribution of fault-related fractures

NASA Astrophysics Data System (ADS)

Maerten, Laurent; Maerten, Frantz; Lejri, Mostfa

2018-03-01

Whatever the processes involved in the natural fracture development in the subsurface, fracture patterns are often affected by the local stress field during propagation. This homogeneous or heterogeneous local stress field can be of mechanical and/or tectonic origin. In this contribution, we focus on the fracture-pattern development where active faults perturb the stress field, and are affected by fluid pressure and sliding friction along the faults. We analyse and geomechanically model two fractured outcrops in UK (Nash Point) and in France (Les Matelles). We demonstrate that the observed local radial joint pattern is best explained by local fluid pressure along the faults and that observed fracture pattern can only be reproduced when fault friction is very low (μ < 0.2). Additionally, in the case of sub-vertical faults, we emphasize that the far field horizontal stress ratio does not affect stress trajectories, or fracture patterns, unless fault normal displacement (dilation or contraction) is relatively large.

Effects of perilymphatic pressure, sodium nitroprusside, and bupivacaine on cochlear fluid pH of guinea pigs.

PubMed

Suzuki, Masaaki; Kotani, Ryosuke

2015-01-01

Hydrostatic positive pressure and vasoconstrictor acidified the cochlear fluids, whereas the vasodilator made the fluids alkaline. CBF might play a role in regulating cochlea fluid pH. Cochlea fluid pH is highly dependent on the HCO3(-)/CO2 buffer system. Cochlear blood flow (CBF) supplies O2 and removes CO2. It is speculated that cochlear blood flow changes might affect the balance of the HCO3(-)/CO2 buffer system in the cochlea. It is known that the elevation of inner ear pressure decreases the CBF, and local application of vasodilating or vasoconstricting agents directly to the cochlea changes the CBF. The purpose of this study was to elucidate the effect of positive hydrostatic inner ear pressure and application of a vasodilator and vasoconstrictor of cochlear vessels on the pH of the endolymph and perilymph. The authors performed animal physiological experiments on 30 guinea pigs. Hydrostatic positive pressure was infused through a glass capillary tube inserted into the scala tympani of the basal turn. The vasodilator, nitric oxide donor (sodium nitroprusside; SNP), and the vasoconstrictor, bupivacaine, were placed topically onto the round window of the guinea pig cochlea. Endolymph pH (pHe) and endocochlear potential (EP) were monitored by double-barreled ion-selective microelectrodes in the second turn of the guinea pig cochlea. During the topical application study, scala vestibuli perilymph pH (pHv) was also measured simultaneously in the second turn. The application of hydrostatic positive pressure caused a decrease in pHe and EP. Positive perilymphatic pressure caused the endolymph to become acidic pressure-dependently. Application of 3.0% SNP evoked an increase in both the pHe and pHv, following by a gradual recovery to baseline levels. On the other hand, 0.5% bupivacaine caused a decrease in both the pHe and pHv. The EP during topical application showed slight, non-significant changes.

Extreme pressure differences at 0900 NZST and winds across New Zealand

NASA Astrophysics Data System (ADS)

Salinger, M. James; Griffiths, Georgina M.; Gosai, Ashmita

2005-07-01

Trends in extremes in station daily sea-level pressure differences at 0900 NZST are examined, and extreme daily wind gusts, across New Zealand, since the 1960s. Annual time series were examined (with indices of magnitude and frequency over threshold percentiles) from the daily indices selected. These follow from earlier indices of normalized monthly mean sea-level pressure differences between station pairs, except the daily indices are not normalized. The frequency statistics quantify the number of extreme zonal (westerly and easterly), or extreme meridional (southerly or northerly), pressure gradient events. The frequency and magnitude of extreme westerly episodes has increased slightly over New Zealand, with a significant increase in the westerly extremes to the south of New Zealand. In contrast, the magnitude and frequency of easterly extremes has decreased over New Zealand, but increased to the south, with some trends weakly significant. The frequency and magnitude of daily southerly extremes has decreased significantly in the region.Extreme daily wind gust events at key climate stations in New Zealand and at Hobart, Australia, are highly likely to be associated with an extreme daily pressure difference. The converse was less likely to hold: extreme wind gusts were not always observed on days with extreme daily pressure difference, probably due to the strong influence that topography has on localized station winds. Significant correlations exist between the frequency indices and both annual-average mean sea-level pressures around the Australasian region and annual-average sea surface temperature (SST) anomalies in the Southern Hemisphere. These correlations are generally stronger for indices of extreme westerly or extreme southerly airflows. Annual-average pressures in the Tasman Sea or Southern Ocean are highly correlated to zonal indices (frequency of extreme westerlies). SST anomalies in the NINO3 region or on either side of the South Island are significantly correlated with the frequency of extreme westerly airflows.

Pore pressure migration during hydraulic stimulation due to permeability enhancement by low-pressure subcritical fracture slip

NASA Astrophysics Data System (ADS)

Mukuhira, Yusuke; Moriya, Hirokazu; Ito, Takatoshi; Asanuma, Hiroshi; Häring, Markus

2017-04-01

Understanding the details of pressure migration during hydraulic stimulation is important for the design of an energy extraction system and reservoir management, as well as for the mitigation of hazardous-induced seismicity. Based on microseismic and regional stress information, we estimated the pore pressure increase required to generate shear slip on an existing fracture during stimulation. Spatiotemporal analysis of pore pressure migration revealed that lower pore pressure migrates farther and faster and that higher pore pressure migrates more slowly. These phenomena can be explained by the relationship between fracture permeability and stress state criticality. Subcritical fractures experience shear slip following smaller increases of pore pressure and promote migration of pore pressure because of their enhanced permeability. The difference in migration rates between lower and higher pore pressures suggests that the optimum wellhead pressure is the one that can stimulate relatively permeable fractures, selectively. Its selection optimizes economic benefits and minimizes seismic risk.

Evaluation of a locally homogeneous flow model of spray combustion

NASA Technical Reports Server (NTRS)

Mao, C. P.; Szekely, G. A., Jr.; Faeth, G. M.

1980-01-01

A model of spray combustion which employs a second-order turbulence model was developed. The assumption of locally homogeneous flow is made, implying infinitely fast transport rates between the phase. Measurements to test the model were completed for a gaseous n-propane flame and an air atomized n-pentane spray flame, burning in stagnant air at atmospheric pressure. Profiles of mean velocity and temperature, as well as velocity fluctuations and Reynolds stress, were measured in the flames. The predictions for the gas flame were in excellent agreement with the measurements. The predictions for the spray were qualitatively correct, but effects of finite rate interphase transport were evident, resulting in a overstimation of the rate development of the flow. Predictions of spray penetration length at high pressures, including supercritical combustion conditions, were also completed for comparison with earlier measurements. Test conditions involved a pressure atomized n-pentane spray, burning in stagnant air at pressures of 3, 5, and 9 MPa. The comparison between predictions and measurements was fair. This is not a very sensitive test of the model, however, and further high pressure experimental and theoretical results are needed before a satisfactory assessment of the locally homogeneous flow approximation can be made.

The influence of local pressure on evaluation parameters of skin blood perfusion and fluorescence

NASA Astrophysics Data System (ADS)

Zherebtsov, E. A.; Kandurova, K. Y.; Seryogina, E. S.; Kozlov, I. O.; Dremin, V. V.; Zherebtsova, A. I.; Dunaev, A. V.; Meglinski, I.

2017-03-01

This article presents the results of the study of the pressure applied on optical diagnostic probes as a significant factor affecting the results of measurements. During stepwise increasing and decreasing of local pressure on skin we conducted measurements using the methods of laser Doppler flowmetry and fluorescence spectroscopy. It was found out that pressure on optical probe has sufficient impact on skin microcirculation to affect registered fluorescence intensity. Data obtained in this study are of interest for design and development of diagnostic technologies for wearable devices. This data will also inform further investigation into issues of compensation of blood absorption influence on fluorescence spectrum, allowing increased accuracy and reproducibility of measurements by fluorescence spectroscopy methods in optical diagnosis.

Resistant Traits in Digital Organisms Do Not Revert Preselection Status despite Extended Deselection: Implications to Microbial Antibiotics Resistance

PubMed Central

Castillo, Clarence F. G.; Ling, Maurice H. T.

2014-01-01

Antibiotics resistance is a serious biomedical issue as formally susceptible organisms gain resistance under its selective pressure. There have been contradictory results regarding the prevalence of resistance following withdrawal and disuse of the specific antibiotics. Here, we use experimental evolution in “digital organisms” to examine the rate of gain and loss of resistance under the assumption that there is no fitness cost for maintaining resistance. Our results show that selective pressure is likely to result in maximum resistance with respect to the selective pressure. During deselection as a result of disuse of the specific antibiotics, a large initial loss and prolonged stabilization of resistance are observed, but resistance is not lost to the stage of preselection. This suggests that a pool of partial persists organisms persist long after withdrawal of selective pressure at a relatively constant proportion. Hence, contradictory results regarding the prevalence of resistance following withdrawal and disuse of the specific antibiotics may be a statistical variation about constant proportion. Our results also show that subsequent reintroduction of the same selective pressure results in rapid regain of maximal resistance. Thus, our simulation results suggest that complete elimination of specific antibiotics resistance is unlikely after the disuse of antibiotics once a resistant pool of microorganisms has been established. PMID:24977157

Capturing Pressure Oscillations in Numerical Simulations of Internal Combustion Engines

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

Gubba, Sreenivasa Rao; Jupudi, Ravichandra S.; Pasunurthi, Shyam Sundar

In an earlier publication, the authors compared numerical predictions of the mean cylinder pressure of diesel and dual-fuel combustion, to that of measured pressure data from a medium-speed, large-bore engine. In these earlier comparisons, measured data from a flush-mounted in-cylinder pressure transducer showed notable and repeatable pressure oscillations which were not evident in the mean cylinder pressure predictions from computational fluid dynamics (CFD). In this paper, the authors present a methodology for predicting and reporting the local cylinder pressure consistent with that of a measurement location. Such predictions for large-bore, medium-speed engine operation demonstrate pressure oscillations in accordance with thosemore » measured. The temporal occurrences of notable pressure oscillations were during the start of combustion and around the time of maximum cylinder pressure. With appropriate resolutions in time steps and mesh sizes, the local cell static pressure predicted for the transducer location showed oscillations in both diesel and dual-fuel combustion modes which agreed with those observed in the experimental data. Fast Fourier transform (FFT) analysis on both experimental and calculated pressure traces revealed that the CFD predictions successfully captured both the amplitude and frequency range of the oscillations. Furthermore, resolving propagating pressure waves with the smaller time steps and grid sizes necessary to achieve these results required a significant increase in computer resources.« less

Capturing Pressure Oscillations in Numerical Simulations of Internal Combustion Engines

DOE PAGES

Gubba, Sreenivasa Rao; Jupudi, Ravichandra S.; Pasunurthi, Shyam Sundar; ...

2018-04-09

In an earlier publication, the authors compared numerical predictions of the mean cylinder pressure of diesel and dual-fuel combustion, to that of measured pressure data from a medium-speed, large-bore engine. In these earlier comparisons, measured data from a flush-mounted in-cylinder pressure transducer showed notable and repeatable pressure oscillations which were not evident in the mean cylinder pressure predictions from computational fluid dynamics (CFD). In this paper, the authors present a methodology for predicting and reporting the local cylinder pressure consistent with that of a measurement location. Such predictions for large-bore, medium-speed engine operation demonstrate pressure oscillations in accordance with thosemore » measured. The temporal occurrences of notable pressure oscillations were during the start of combustion and around the time of maximum cylinder pressure. With appropriate resolutions in time steps and mesh sizes, the local cell static pressure predicted for the transducer location showed oscillations in both diesel and dual-fuel combustion modes which agreed with those observed in the experimental data. Fast Fourier transform (FFT) analysis on both experimental and calculated pressure traces revealed that the CFD predictions successfully captured both the amplitude and frequency range of the oscillations. Furthermore, resolving propagating pressure waves with the smaller time steps and grid sizes necessary to achieve these results required a significant increase in computer resources.« less

Ischaemic stroke management at Al-Shifa Hospital in the Gaza Strip: a clinical audit.

PubMed

Abukaresh, Amir; Al-Abadlah, Rami; Böttcher, Bettina; El-Essi, Khamis

2018-02-21

In the 2014 Palestinian annual health report, cerebrovascular accident was ranked as the third leading cause of death in the occupied Palestinian territory. Cerebrovascular accident is also one the most common causes of disability worldwide. Good management decreases mortality and morbidity. The aim of this study was to assess the current management of patients with ischaemic stroke at the Al-Shifa Hospital and to compare this with international guidelines. For this clinical audit, we used simple random sampling to select files of patients admitted with the diagnosis of ischaemic stroke to the Al-Shifa Hospital. Data collection sheets were completed, and clinical practice was compared with the 2013 American Stroke Association guidelines. Between January and June, 2016, 254 patients were admitted with ischaemic stroke, haemorrhagic stroke, or transient ischaemic attack. We selected 55 patient files. The International Classification of Diseases coding for cerebral infarction in patient files was relatively good, with 92% of files correctly coded. However, we found a substantial weakness in the documentation of duration, progression of symptoms (documented in 20% of files only), and physiotherapy assessment. Most essential acute investigations were done on time (for all [100%] patients needing blood count, renal function tests, and CT scan and for 42 [76%] patients needing ECG). However, thrombolytic drugs were not used because they were not available. Long-term antiplatelet therapy was provided properly to 51 (92%) patients discharged from hospital. However, the initial doses of antiplatelet therapy were generally lower than the international recommendations. Findings also showed a marked inconformity of blood pressure management, especially with respect to the treatment decision and the choice of antihypertensive drug. No local guidelines exist. Furthermore, the lack of availability of thrombolysis medication and the poor deviation in blood pressure management show a lack of evidence-based practice. These findings point to the urgent need for the development of local, evidence-based guidelines. None. Copyright © 2018 Elsevier Ltd. All rights reserved.

32 CFR 1605.52 - Composition of local boards.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Composition of local boards. 1605.52 Section... SELECTIVE SERVICE SYSTEM ORGANIZATION Local Boards § 1605.52 Composition of local boards. The Director of Selective Service shall prescribe the number of members of local boards. ...

32 CFR 1605.52 - Composition of local boards.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Composition of local boards. 1605.52 Section... SELECTIVE SERVICE SYSTEM ORGANIZATION Local Boards § 1605.52 Composition of local boards. The Director of Selective Service shall prescribe the number of members of local boards. ...

The basic science and mathematics of random mutation and natural selection.

PubMed

Kleinman, Alan

2014-12-20

The mutation and natural selection phenomenon can and often does cause the failure of antimicrobial, herbicidal, pesticide and cancer treatments selection pressures. This phenomenon operates in a mathematically predictable behavior, which when understood leads to approaches to reduce and prevent the failure of the use of these selection pressures. The mathematical behavior of mutation and selection is derived using the principles given by probability theory. The derivation of the equations describing the mutation and selection phenomenon is carried out in the context of an empirical example. Copyright © 2014 John Wiley & Sons, Ltd.

Coupling Spatiotemporal Community Assembly Processes to Changes in Microbial Metabolism.

PubMed

Graham, Emily B; Crump, Alex R; Resch, Charles T; Fansler, Sarah; Arntzen, Evan; Kennedy, David W; Fredrickson, Jim K; Stegen, James C

2016-01-01

Community assembly processes generate shifts in species abundances that influence ecosystem cycling of carbon and nutrients, yet our understanding of assembly remains largely separate from ecosystem-level functioning. Here, we investigate relationships between assembly and changes in microbial metabolism across space and time in hyporheic microbial communities. We pair sampling of two habitat types (i.e., attached and planktonic) through seasonal and sub-hourly hydrologic fluctuation with null modeling and temporally explicit multivariate statistics. We demonstrate that multiple selective pressures-imposed by sediment and porewater physicochemistry-integrate to generate changes in microbial community composition at distinct timescales among habitat types. These changes in composition are reflective of contrasting associations of Betaproteobacteria and Thaumarchaeota with ecological selection and with seasonal changes in microbial metabolism. We present a conceptual model based on our results in which metabolism increases when oscillating selective pressures oppose temporally stable selective pressures. Our conceptual model is pertinent to both macrobial and microbial systems experiencing multiple selective pressures and presents an avenue for assimilating community assembly processes into predictions of ecosystem-level functioning.

Neuronal nitric oxide synthase control mechanisms in the cutaneous vasculature of humans in vivo

PubMed Central

Kellogg, Dean L; Zhao, Joan L; Wu, Yubo

2008-01-01

The physiological roles of constituitively expressed nitric oxide synthase (NOS) isoforms in humans, in vivo, are unknown. Cutaneous vasodilatation during both central nervous system-mediated, thermoregulatory reflex responses to whole-body heat stress and during peripheral axon reflex-mediated, local responses to skin warming in humans depend on nitric oxide (NO) generation by constituitively expressed NOS of uncertain isoform. We hypothesized that neuronal NOS (nNOS, NOS I) effects cutaneous vasodilatation during whole-body heat stress, but not during local skin warming. We examined the effects of the nNOS inhibitor 7-nitroindazole (7-NI) administered by intradermal microdialysis on vasodilatation induced by whole-body heat stress or local skin warming. Skin blood flow (SkBF) was monitored by laser–Doppler flowmetry (LDF). Blood pressure (MAP) was monitored and cutaneous vascular conductance calculated (CVC = LDF/MAP). In protocol 1, whole-body heat stress was induced with water-perfused suits. In protocol 2, local skin warming was induced through local warming units at LDF sites. At the end of each protocol, 56 mm sodium nitroprusside was perfused at microdialysis sites to raise SkBF to maximal levels for data normalization. 7-NI significantly attenuated CVC increases during whole-body heat stress (P < 0.05), but had no effect on CVC increases induced by local skin warming (P > 0.05). These diametrically opposite effects of 7-NI on two NO-dependent processes verify selective nNOS antagonism, thus proving that the nNOS isoform affects NO increases and hence vasodilatation during centrally mediated, reflex responses to whole-body heat stress, but not during locally mediated, axon reflex responses to local skin warming. We conclude that the constituitively expressed nNOS isoform has distinct physiological roles in cardiovascular control mechanisms in humans, in vivo. PMID:18048451

LOCAL TADPOLE GALAXIES

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

Elmegreen, Debra Meloy; Putko, Joseph; Dewberry, Janosz

2012-05-10

Tadpole galaxies have a giant star-forming region at the end of an elongated intensity distribution. Here we use Sloan Digital Sky Survey data to determine the ages, masses, and surface densities of the heads and tails in 14 local tadpoles selected from the Kiso and Michigan surveys of UV-bright galaxies, and we compare them to tadpoles previously studied in the Hubble Ultra Deep Field. The young stellar mass in the head scales linearly with rest-frame galaxy luminosity, ranging from {approx}10{sup 5} M{sub Sun} at galaxy absolute magnitude U = -13 mag to 10{sup 9} M{sub Sun} at U = -20more » mag. The corresponding head surface density increases from several M {sub Sun} pc{sup -2} locally to 10-100 M{sub Sun} pc{sup -2} at high redshift, and the star formation rate (SFR) per unit area in the head increases from {approx}0.01 M{sub Sun} yr{sup -1} kpc{sup -2} locally to {approx}1 M{sub Sun} yr{sup -1} kpc{sup -2} at high z. These local values are normal for star-forming regions, and the increases with redshift are consistent with other cosmological SFRs, most likely reflecting an increase in gas abundance. The tails in the local sample look like bulge-free galaxy disks. Their photometric ages decrease from several Gyr to several hundred Myr with increasing z, and their surface densities are more constant than the surface densities of the heads. The far-outer intensity profiles in the local sample are symmetric and exponential. We suggest that most local tadpoles are bulge-free galaxy disks with lopsided star formation, perhaps from environmental effects such as ram pressure or disk impacts, or from a Jeans length comparable to half the disk size.« less

Selective Oxidation and Reactive Wetting during Galvanizing of a CMnAl TRIP-Assisted Steel

NASA Astrophysics Data System (ADS)

Bellhouse, E. M.; McDermid, J. R.

2011-09-01

A transformation induced plasticity (TRIP)-assisted steel with 0.2 pct C, 1.5 pct Mn, and 1.5 pct Al was successfully galvanized using a thermal cycle previously shown to produce an excellent combination of strength and ductility. The steel surface chemistry and oxide morphology were determined as a function of process atmosphere oxygen partial pressure. For the 220 K (-53 °C) dew point (dp) + 20 pct H2 atmosphere, the oxide morphology was a mixture of films and nodules. For the 243 K (-30 °C) dp + 5 pct H2 atmosphere, nodules of MnO were found primarily at grain boundaries. For the 278 K (+5 °C) dp + 5 pct H2 atmosphere, nodules of metallic Fe were found on the surface as a result of alloy element internal oxidation. The steel surface chemistry and oxide morphology were then related to the reactive wetting behavior during continuous hot dip galvanizing. Good wetting was obtained using the two lower oxygen partial pressure process atmospheres [220 K dp and 243 K dp (-53 °C dp and -30 °C dp)]. An increase in the number of bare spots was observed when using the higher oxygen partial pressure process atmosphere (+5 °C dp) due to the increased thickness of localized oxide films.

Dynamic relationship between ocean bottom pressure and bathymetry around northern part of Hikurangi

NASA Astrophysics Data System (ADS)

Muramoto, T.; Inazu, D.; Ito, Y.; Hino, R.; Suzuki, S.

2017-12-01

In recent years, observation using ocean bottom pressure recorders for the purpose of the evaluation of sea floor crustal deformation is in great vogue. The observation network set up for the observation of sea floor is densely spaced compared with the instrument network for the observation of ocean. Therefore, it has the characteristic that it can observe phenomena on a local scale. In this study, by using these in situ data, we discuss ocean phenomena on a local scale. In this study, we use a high-resolution ocean model (Inazu Ocean Model) driven by surface air pressure and surface wind vector published by the Japan Meteorological Agency. We perform a hindcast experiment for ocean bottom pressure anomaly from April 2013 to June 2017. Then, we compare these results with in situ data. In this study, we use observed pressure records which were recorded by autonomous type instrument spanning a period from April 2013 to June 2017 off the coast of North Island in New Zealand. Consequently, we found this model can simulate not only the amplitude but also phase of non-tidal oceanic variation of East Cape Current (ECC) off the coast of North Island of New Zealand. Then, we calculate cross-correlation coefficient between the data at the OBP sites. We revealed that the ocean bottom pressure shows different behavior on the west side from the east side of edge of the continental shelf. This result implies that the submarine slope induces a dynamic effect and contributes to the seasonal variation of ocean bottom pressure. In addition, we calculate the velocity of the surface current in this area using our model, and consider the relationship between it and ocean bottom pressure variation. Taken together, we can say that the barotropic flow in the direction of south-west extends to the bottom of the sea in this area. Therefore, the existence of local cross-isobath currents is suggested. Our result indicates bathymetry has dynamic effect to ocean circulation on local scale and at the same time the surface ocean circulation contributes to ocean bottom pressure considerably.

Design of a mercury Propellant Storage and Distribution assembly

NASA Technical Reports Server (NTRS)

Holcomb, L. B.; Womack, J. R.

1973-01-01

A study has been conducted of a Propellant Storage and Distribution (PSD) assembly for a solar electric propulsion (SEP) thrust subsystem. As a result of the trade-off study an elastomeric diaphragm propellant tank with nitrogen blowdown pressurization was the method selected for propellant expulsion. This study included the following propellant management devices: surface tension, metallic bellows, and metallic and elastomeric diaphragms. Pressurant supply concepts investigated were blowdown, externally pressure regulated, vaporizing Freon 113, and heated CO2/Zeolite. The configuration selected consists of a single propellant tank, a single main propellant latching-solenoid valve, and individual thruster latching-solenoid valves. Stainless steel was the selected tankage material and AF-E-332 was the selected diaphragm material. The PSD design characteristics and interfaces are summarized.

Patterns of Endemism and Habitat Selection in Coalbed Microbial Communities

PubMed Central

Lawson, Christopher E.; Strachan, Cameron R.; Williams, Dominique D.; Koziel, Susan; Hallam, Steven J.

2015-01-01

Microbially produced methane, a versatile, cleaner-burning alternative energy resource to fossil fuels, is sourced from a variety of natural and engineered ecosystems, including marine sediments, anaerobic digesters, shales, and coalbeds. There is a prevailing interest in developing environmental biotechnologies to enhance methane production. Here, we use small-subunit rRNA gene sequencing and metagenomics to better describe the interplay between coalbed methane (CBM) well conditions and microbial communities in the Alberta Basin. Our results show that CBM microbial community structures display patterns of endemism and habitat selection across the Alberta Basin, consistent with observations from other geographical locations. While some phylum-level taxonomic patterns were observed, relative abundances of specific taxonomic groups were localized to discrete wells, likely shaped by local environmental conditions, such as coal rank and depth-dependent physicochemical conditions. To better resolve functional potential within the CBM milieu, a metagenome from a deep volatile-bituminous coal sample was generated. This sample was dominated by Rhodobacteraceae genotypes, resolving a near-complete population genome bin related to Celeribacter sp. that encoded metabolic pathways for the degradation of a wide range of aromatic compounds and the production of methanogenic substrates via acidogenic fermentation. Genomic comparisons between the Celeribacter sp. population genome and related organisms isolated from different environments reflected habitat-specific selection pressures that included nitrogen availability and the ability to utilize diverse carbon substrates. Taken together, our observations reveal that both endemism and metabolic specialization should be considered in the development of biostimulation strategies for nonproductive wells or for those with declining productivity. PMID:26341214

Mechanical behavior and localized failure modes in a porous basalt from the Azores

NASA Astrophysics Data System (ADS)

Loaiza, S.; Fortin, J.; Schubnel, A.; Gueguen, Y.; Vinciguerra, S.; Moreira, M.

2012-10-01

Basaltic rocks are the main component of the oceanic upper crust, thus of potential interest for water and geothermal resources, storage of CO2 and volcanic edifice stability. In this work, we investigated experimentally the mechanical behavior and the failure modes of a porous basalt, with an initial connected porosity of 18%. Results were acquired under triaxial compression experiments at confining pressure in the range of 25-200 MPa on water saturated samples. In addition, a purely hydrostatic test was also performed to reach the pore collapse critical pressure P*. During hydrostatic loading, our results show that the permeability is highly pressure dependent, which suggests that the permeability is mainly controlled by pre-existing cracks. When the sample is deformed at pressure higher than the pore collapse pressure P*, some very small dilatancy develops due to microcracking, and an increase in permeability is observed. Under triaxial loading, two modes of deformation can be highlighted. At low confining pressure (Pc < 50 MPa), the samples are brittle and shear localization occurs. For confining pressure > 50 MPa, the stress-strain curves are characterized by strain hardening and volumetric compaction. Stress drops are also observed, suggesting that compaction may be localized. The presence of compaction bands is confirmed by our microstructure analysis. In addition, the mechanical data allows us to plot the full yield surface for this porous basalt, which follows an elliptic cap as previously observed in high porosity sandstones and limestones.

Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a slot air jet

NASA Astrophysics Data System (ADS)

M, Adimurthy; Katti, Vadiraj V.

2017-02-01

Local distribution of wall static pressure and heat transfer on a smooth flat plate impinged by a normal slot air jet is experimental investigated. Present study focuses on the influence of jet-to-plate spacing ( Z/D h ) (0.5-10) and Reynolds number (2500-20,000) on the fluid flow and heat transfer distribution. A single slot jet with an aspect ratio ( l/b) of about 22 is chosen for the current study. Infrared Thermal Imaging technique is used to capture the temperature data on the target surface. Local heat transfer coefficients are estimated from the thermal images using `SMART VIEW' software. Wall static pressure measurement is carried out for the specified range of Re and Z/D h . Wall static pressure coefficients are seen to be independent of Re in the range between 5000 and 15,000 for a given Z/D h . Nu values are higher at the stagnation point for all Z/D h and Re investigated. For lower Z/D h and higher Re, secondary peaks are observed in the heat transfer distributions. This may be attributed to fluid translating from laminar to turbulent flow on the target plate. Heat transfer characteristics are explained based on the simplified flow assumptions and the pressure data obtained using Differential pressure transducer and static pressure probe. Semi-empirical correlation for the Nusselt number in the stagnation region is proposed.

Capillary pressure spectrometry: Toward a new method for the measurement of the fractional wettability of porous media

NASA Astrophysics Data System (ADS)

Sygouni, Varvara; Tsakiroglou, Christos D.; Payatakes, Alkiviades C.

2006-05-01

A transparent porous medium of controlled fractional wettability is fabricated by mixing intermediate-wet glass microspheres with strongly oil-wet polytetrafluouroethylene microspheres, and packing them between two transparent glass plates. Silicon oil is displaced by water, the growth pattern is video-recorded, and the transient response of the pressure drop across the pore network is measured for various fractions of oil-wet particles. The measured global capillary pressure fluctuates as the result of the variation of the equilibrium curvature of menisci between local maxima and local minima. With the aid of wavelets, the transient response of the capillary pressure is transformed to a capillary pressure spectrum (CPS). The peaks of the CPS are used to identify the most significant flow events and correlate their amplitude with the spatial distribution of fractional wettability. The flow events are closely related with the fluctuations of the capillary pressure and are classified into three main categories: motion in pore clusters, generation/expansion of capillary fingers, coalescence of interfaces. The amplitude of the peaks of CPS is related quasilinearly with a local coefficient of fractional wettability presuming that the same class of flow events is concerned. Approximate calculations of the maximum meniscus curvature in pores of converging-diverging geometry and uniform wettability in combination with simple mixing laws predict satisfactorily the experimentally measured average prebreakthrough capillary pressure as a function of the fraction of the oil-wet particles.

Phenotypic Divergence among West European Populations of Reed Bunting Emberiza schoeniclus: The Effects of Migratory and Foraging Behaviours

PubMed Central

Neto, Júlio M.; Gordinho, Luís; Belda, Eduardo J.; Marín, Marcial; Monrós, Juan S.; Fearon, Peter; Crates, Ross

2013-01-01

Divergent selection and local adaptation are responsible for many phenotypic differences between populations, potentially leading to speciation through the evolution of reproductive barriers. Here we evaluated the morphometric divergence among west European populations of Reed Bunting in order to determine the extent of local adaptation relative to two important selection pressures often associated with speciation in birds: migration and diet. We show that, as expected by theory, migratory E. s. schoeniclus had longer and more pointed wings and a slightly smaller body mass than the resident subspecies, with the exception of E. s. lusitanica, which despite having rounder wings was the smallest of all subspecies. Tail length, however, did not vary according to the expectation (shorter tails in migrants) probably because it is strongly correlated with wing length and might take longer to evolve. E. s. witherbyi, which feed on insects hiding inside reed stems during the winter, had a very thick, stubby bill. In contrast, northern populations, which feed on seeds, had thinner bills. Despite being much smaller, the southern E. s. lusitanica had a significantly thicker, longer bill than migratory E. s. schoeniclus, whereas birds from the UK population had significantly shorter, thinner bills. Geometric morphometric analyses revealed that the southern subspecies have a more convex culmen than E. s. schoeniclus, and E. s. lusitanica differs from the nominate subspecies in bill shape to a greater extent than in linear bill measurements, especially in males. Birds with a more convex culmen are thought to exert a greater strength at the bill tip, which is in agreement with their feeding technique. Overall, the three subspecies occurring in Western Europe differ in a variety of traits following the patterns predicted from their migratory and foraging behaviours, strongly suggesting that these birds have became locally adapted through natural selection. PMID:23667594

Social influence on selection behaviour: Distinguishing local- and global-driven preferential attachment

PubMed Central

Pan, Xue; Liu, Kecheng

2017-01-01

Social influence drives human selection behaviours when numerous objects competing for limited attentions, which leads to the ‘rich get richer’ dynamics where popular objects tend to get more attentions. However, evidences have been found that, both the global information of the whole system and the local information among one’s friends have significant influence over the one’s selection. Consequently, a key question raises that, it is the local information or the global information more determinative for one’s selection? Here we compare the local-based influence and global-based influence. We show that, the selection behaviour is mainly driven by the local popularity of the objects while the global popularity plays a supplementary role driving the behaviour only when there is little local information for the user to refer to. Thereby, we propose a network model to describe the mechanism of user-object interaction evolution with social influence, where the users perform either local-driven or global-driven preferential attachments to the objects, i.e., the probability of an objects to be selected by a target user is proportional to either its local popularity or global popularity. The simulation suggests that, about 75% of the attachments should be driven by the local popularity to reproduce the empirical observations. It means that, at least in the studied context where users chose businesses on Yelp, there is a probability of 75% for a user to make a selection according to the local popularity. The proposed model and the numerical findings may shed some light on the study of social influence and evolving social systems. PMID:28406984

Social influence on selection behaviour: Distinguishing local- and global-driven preferential attachment.

PubMed

Pan, Xue; Hou, Lei; Liu, Kecheng

2017-01-01

Social influence drives human selection behaviours when numerous objects competing for limited attentions, which leads to the 'rich get richer' dynamics where popular objects tend to get more attentions. However, evidences have been found that, both the global information of the whole system and the local information among one's friends have significant influence over the one's selection. Consequently, a key question raises that, it is the local information or the global information more determinative for one's selection? Here we compare the local-based influence and global-based influence. We show that, the selection behaviour is mainly driven by the local popularity of the objects while the global popularity plays a supplementary role driving the behaviour only when there is little local information for the user to refer to. Thereby, we propose a network model to describe the mechanism of user-object interaction evolution with social influence, where the users perform either local-driven or global-driven preferential attachments to the objects, i.e., the probability of an objects to be selected by a target user is proportional to either its local popularity or global popularity. The simulation suggests that, about 75% of the attachments should be driven by the local popularity to reproduce the empirical observations. It means that, at least in the studied context where users chose businesses on Yelp, there is a probability of 75% for a user to make a selection according to the local popularity. The proposed model and the numerical findings may shed some light on the study of social influence and evolving social systems.

Absence of positive selection on CenH3 in Luzula suggests that holokinetic chromosomes may suppress centromere drive.

PubMed

Zedek, František; Bureš, Petr

2016-12-01

The centromere drive theory explains diversity of eukaryotic centromeres as a consequence of the recurrent conflict between centromeric repeats and centromeric histone H3 (CenH3), in which selfish centromeres exploit meiotic asymmetry and CenH3 evolves adaptively to counterbalance deleterious consequences of driving centromeres. Accordingly, adaptively evolving CenH3 has so far been observed only in eukaryotes with asymmetric meiosis. However, if such evolution is a consequence of centromere drive, it should depend not only on meiotic asymmetry but also on monocentric or holokinetic chromosomal structure. Selective pressures acting on CenH3 have never been investigated in organisms with holokinetic meiosis despite the fact that holokinetic chromosomes have been hypothesized to suppress centromere drive. Therefore, the present study evaluates selective pressures acting on the CenH3 gene in holokinetic organisms for the first time, specifically in the representatives of the plant genus Luzula (Juncaceae), in which the kinetochore formation is not co-localized with any type of centromeric repeat. PCR, cloning and sequencing, and database searches were used to obtain coding CenH3 sequences from Luzula species. Codon substitution models were employed to infer selective regimes acting on CenH3 in Luzula KEY RESULTS: In addition to the two previously published CenH3 sequences from L. nivea, 16 new CenH3 sequences have been isolated from 12 Luzula species. Two CenH3 isoforms in Luzula that originated by a duplication event prior to the divergence of analysed species were found. No signs of positive selection acting on CenH3 in Luzula were detected. Instead, evidence was found that selection on CenH3 of Luzula might have been relaxed. The results indicate that holokinetism itself may suppress centromere drive and, therefore, holokinetic chromosomes might have evolved as a defence against centromere drive. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Wet atmospheric generation apparatus

NASA Technical Reports Server (NTRS)

Hamner, Richard M. (Inventor); Allen, Janice K. (Inventor)

1990-01-01

The invention described relates to an apparatus for providing a selectively humidified gas to a camera canister containing cameras and film used in space. A source of pressurized gas (leak test gas or motive gas) is selected by a valve, regulated to a desired pressure by a regulator, and routed through an ejector (venturi device). A regulated source of water vapor in the form of steam from a heated reservoir is coupled to a low pressure region of the ejector which mixes with high velocity gas flow through the ejector. This mixture is sampled by a dew point sensor to obtain dew point thereof (ratio of water vapor to gas) and the apparatus adjusted by varying gas pressure or water vapor to provide a mixture at a connector having selected humidity content.

Urban noise and the cultural evolution of bird songs.

PubMed

Luther, David; Baptista, Luis

2010-02-07

In urban environments, anthropogenic noise can interfere with animal communication. Here we study the influence of urban noise on the cultural evolution of bird songs. We studied three adjacent dialects of white-crowned sparrow songs over a 30-year time span. Urban noise, which is louder at low frequencies, increased during our study period and therefore should have created a selection pressure for songs with higher frequencies. We found that the minimum frequency of songs increased both within and between dialects during the 30-year time span. For example, the dialect with the highest minimum frequency is in the process of replacing another dialect that has lower frequency songs. Songs with the highest minimum frequency were favoured in this environment and should have the most effective transmission properties. We suggest that one mechanism that influences how dialects, and cultural traits in general, are selected and transmitted from one generation to the next is the dialect's ability to be effectively communicated in the local environment.

Experimental Insights into Ground-State Selection of Quantum XY Pyrochlores

NASA Astrophysics Data System (ADS)

Hallas, Alannah M.; Gaudet, Jonathan; Gaulin, Bruce D.

2018-03-01

Extensive experimental investigations of the magnetic structures and excitations in the XY pyrochlores have been carried out over the past decade. Three families of XY pyrochlores have emerged: Yb2B2O7, Er2B2O7, and, most recently, [Formula: see text]Co2F7. In each case, the magnetic cation (either Yb, Er, or Co) exhibits XY anisotropy within the local pyrochlore coordinates, a consequence of crystal field effects. Materials in these families display rich phase behavior and are candidates for exotic ground states, such as quantum spin ice, and exotic ground-state selection via order-by-disorder mechanisms. In this review, we present an experimental summary of the ground-state properties of the XY pyrochlores, including evidence that they are strongly influenced by phase competition. We empirically demonstrate the signatures for phase competition in a frustrated magnet: multiple heat capacity anomalies, suppressed TN or TC, sample- and pressure-dependent ground states, and unconventional spin dynamics.

Differential positive selection of malaria resistance genes in three indigenous populations of Peninsular Malaysia.

PubMed

Liu, Xuanyao; Yunus, Yushimah; Lu, Dongsheng; Aghakhanian, Farhang; Saw, Woei-Yuh; Deng, Lian; Ali, Mohammad; Wang, Xu; Nor, Fadzilah Mohd; Ghazali, Fadzilah; Rahman, Thuhairah Abdul; Shaari, Shahrul Azlin; Salleh, Mohd Zaki; Phipps, Maude E; Ong, Rick Twee-Hee; Xu, Shuhua; Teo, Yik-Ying; Hoh, Boon-Peng

2015-04-01

The indigenous populations from Peninsular Malaysia, locally known as Orang Asli, continue to adopt an agro-subsistence nomadic lifestyle, residing primarily within natural jungle habitats. Leading a hunter-gatherer lifestyle in a tropical jungle environment, the Orang Asli are routinely exposed to malaria. Here we surveyed the genetic architecture of individuals from four Orang Asli tribes with high-density genotyping across more than 2.5 million polymorphisms. These tribes reside in different geographical locations in Peninsular Malaysia and belong to three main ethno-linguistic groups, where there is minimal interaction between the tribes. We first dissect the genetic diversity and admixture between the tribes and with neighboring urban populations. Later, by implementing five metrics, we investigated the genome-wide signatures for positive natural selection of these Orang Asli, respectively. Finally, we searched for evidence of genomic adaptation to the pressure of malaria infection. We observed that different evolutionary responses might have emerged in the different Orang Asli communities to mitigate malaria infection.

Microbial pattern of pressure ulcer in pediatric patients

NASA Astrophysics Data System (ADS)

Paramita, D. A.; Khairina; Lubis, N. Z.

2018-03-01

Pressure ulcer (PU) is a localized trauma to the skin and or tissue beneath which lies in bony prominence due to pressure or pressure that combines with a sharp surface. Several studies have found that PU is a common problem in pediatrics population. Infection at the site of a PU is the most common complication in which the PU may host a resistant microorganism and may turn into a local infection that will be the source of bacteremia in hospitalized patients. To reveal which is the most common microbial species that underlie in pressure ulcer of pediatrics patients.A cross-sectional study was conducted in July-September 2017, involving 18 PU pediatric patients in Haji Adam Malik Hospital. To each subject, swab culture from the ulcer was madein microbial laboratory in Haji Adam Malik Hospital to determine the microbial pattern. This study found that the most common microbial pattern in pressure ulcers of pediatrics patient in Haji Adam Malik Hospital is Acinetobacter baumannii (22.2%).

Electronic and structural ground state of heavy alkali metals at high pressure

DOE PAGES

Fabbris, G.; Lim, J.; Veiga, L. S. I.; ...

2015-02-17

Here, alkali metals display unexpected properties at high pressure, including emergence of low symmetry crystal structures, that appear to occur due to enhanced electronic correlations among the otherwise nearly-free conduction electrons. We investigate the high pressure electronic and structural ground state of K, Rb, and Cs using x-ray absorption spectroscopy and x-ray diffraction measurements together with ab initio theoretical calculations. The sequence of phase transitions under pressure observed at low temperature is similar in all three heavy alkalis except for the absence of the oC84 phase in Cs. Both the experimental and theoretical results point to pressure-enhanced localization of themore » valence electrons characterized by pseudo-gap formation near the Fermi level and strong spd hybridization. Although the crystal structures predicted to host magnetic order in K are not observed, the localization process appears to drive these alkalis closer to a strongly correlated electron state.« less

Comparative evaluation of endodontic pressure syringe, insulin syringe, jiffy tube, and local anesthetic syringe in obturation of primary teeth: An in vitro study.

PubMed

Hiremath, Mallayya C; Srivastava, Pooja

2016-01-01

The purpose of this in vitro study was to compare four methods of root canal obturation in primary teeth using conventional radiography. A total of 96 root canals of primary molars were prepared and obturated with zinc oxide eugenol. Obturation methods compared were endodontic pressure syringe, insulin syringe, jiffy tube, and local anesthetic syringe. The root canal obturations were evaluated by conventional radiography for the length of obturation and presence of voids. The obtained data were analyzed using Chi-square test. The results showed significant differences between the four groups for the length of obturation (P < 0.05). The endodontic pressure syringe showed the best results (98.5% optimal fillings) and jiffy tube showed the poor results (37.5% optimal fillings) for the length of obturation. The insulin syringe (79.2% optimal fillings) and local anesthetic syringe (66.7% optimal fillings) showed acceptable results for the length of root canal obturation. However, minor voids were present in all the four techniques used. Endodontic pressure syringe produced the best results in terms of length of obturation and controlling paste extrusion from the apical foramen. However, insulin syringe and local anesthetic syringe can be used as effective alternative methods.

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

Fujiwara, K., E-mail: ku.fujiwara@screen.co.jp; Department of Mechanical Engineering, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871; Shibahara, M., E-mail: siba@mech.eng.osaka-u.ac.jp

A classical molecular dynamics simulation was conducted for a system composed of fluid molecules between two planar solid surfaces, and whose interactions are described by the 12-6 Lennard-Jones form. This paper presents a general description of the pressure components and interfacial tension at a fluid-solid interface obtained by the perturbative method on the basis of statistical thermodynamics, proposes a method to consider the pressure components tangential to an interface which are affected by interactions with solid atoms, and applies this method to the calculation system. The description of the perturbative method is extended to subsystems, and the local pressure componentsmore » and interfacial tension at a liquid-solid interface are obtained and examined in one- and two-dimensions. The results are compared with those obtained by two alternative methods: (a) an evaluation of the intermolecular force acting on a plane, and (b) the conventional method based on the virial expression. The accuracy of the numerical results is examined through the comparison of the results obtained by each method. The calculated local pressure components and interfacial tension of the fluid at a liquid-solid interface agreed well with the results of the two alternative methods at each local position in one dimension. In two dimensions, the results showed a characteristic profile of the tangential pressure component which depended on the direction tangential to the liquid-solid interface, which agreed with that obtained by the evaluation of the intermolecular force acting on a plane in the present study. Such good agreement suggests that the perturbative method on the basis of statistical thermodynamics used in this study is valid to obtain the local pressure components and interfacial tension at a liquid-solid interface.« less

7 CFR 247.7 - Selection of local agencies.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 7 Agriculture 4 2010-01-01 2010-01-01 false Selection of local agencies. 247.7 Section 247.7 Agriculture Regulations of the Department of Agriculture (Continued) FOOD AND NUTRITION SERVICE, DEPARTMENT OF AGRICULTURE CHILD NUTRITION PROGRAMS COMMODITY SUPPLEMENTAL FOOD PROGRAM § 247.7 Selection of local agencies...

Enhanced H-mode pedestals with lithium injection in DIII-D

DOE PAGES

Osborne, Thomas H.; Jackson, Gary L.; Yan, Zheng; ...

2015-05-08

Periods of edge localized mode (ELM)-free H-mode with increased pedestal pressure and width were observed in the DIII-D tokamak when density fluctuations localized to the region near the separatrix were present. Injection of a powder of 45 μm diameter lithium particles increased the duration of the enhanced pedestal phases to up to 350 ms, and also increased the likelihood of a transition to the enhanced phase. Lithium injection at a level sufficient for triggering the extended enhanced phases resulted in significant lithium in the plasma core, but carbon and other higher Z impurities as well as radiated power levels weremore » reduced. Recycling of the working deuterium gas appeared unaffected by this level of lithium injection. The ion scale, k θ ρ s ~ 0.1–0.2, density fluctuations propagated in the electron drift direction with f ~ 80 kHz and occurred in bursts every ~1 ms. The fluctuation bursts correlated with plasma loss resulting in a flattening of the pressure profile in a region near the separatrix. This localized flattening 2 allowed higher overall pedestal pressure at the peeling-ballooning stability limit and higher pressure than expected under the EPED model due to reduction of the pressure gradient below the “ballooning critical profile”. Furthermore, reduction of the ion pressure by lithium dilution may contribute to the long ELM-free periods.« less

Competition and coexistence of polar and non-polar states in Sr1-x Ca x TiO3: an investigation using pressure dependent Raman spectroscopy

NASA Astrophysics Data System (ADS)

Tyagi, Shekhar; Sharma, Gaurav; Sathe, Vasant G.

2018-03-01

The competition and cooperation between ferroelectric and anti-ferro-distortion (AFD) instabilities are studied using pressure dependent Raman spectroscopy on polycrystalline powder samples of Sr1-x Ca x TiO3(x  =  0.0, 0.06, 0.25, 0.35). For x  =  0.0 composition, a broad polar mode is detected in the Raman spectra above 6 GPa, while for x  =  0.06 composition, the polar modes appear well above 9 GPa where the AFD modes showed strong suppression. In x  =  0.25 and 0.35 composition, the application of small pressure resulted in the appearance of strong AFD modes suppressing the polar modes. At elevated pressures, re-entrant polar modes are observed along with the broad AFD modes and some new peaks are also observed, signifying the lowering of local symmetry. The reappearance of polar modes is found to be related to pressure induced symmetry disorder at local level, suggesting its electronic origin. The re-entrant polar modes observed at higher pressure values are found to be significantly broad and asymmetric in nature, signifying the development of ferroelectric micro regions/nano domains coexisting with AFD. The lower symmetry at local length scale provides a conducive atmosphere for coexisting AFD and FE instabilities.

Probing microscopic material properties inside simulated membranes through spatially resolved three-dimensional local pressure fields and surface tensions

PubMed Central

Kasson, Peter M.; Hess, Berk; Lindahl, Erik

2013-01-01

Cellular lipid membranes are spatially inhomogeneous soft materials. Materials properties such as pressure and surface tension thus show important microscopic-scale variation that is critical to many biological functions. We present a means to calculate pressure and surface tension in a 3D-resolved manner within molecular-dynamics simulations and show how such measurements can yield important insight. We also present the first corrections to local virial and pressure fields to account for the constraints typically used in lipid simulations that otherwise cause problems in highly oriented systems such as bilayers. Based on simulations of an asymmetric bacterial ion channel in a POPC bilayer, we demonstrate how 3D-resolved pressure can probe for both short-range and long-range effects from the protein on the membrane environment. We also show how surface tension is a sensitive metric for inter-leaflet equilibrium and can be used to detect even subtle imbalances between bilayer leaflets in a membrane-protein simulation. Since surface tension is known to modulate the function of many proteins, this effect is an important consideration for predictions of ion channel function. We outline a strategy by which our local pressure measurements, which we make available within a version of the GROMACS simulation package, may be used to design optimally equilibrated membrane-protein simulations. PMID:23318532

Pressure-induced emission band separation of the hybridized local and charge transfer excited state in a TPE-based crystal.

PubMed

Liu, Xuedan; Li, Aisen; Xu, Weiqing; Ma, Zhiyong; Jia, Xinru

2018-05-08

We herein report a newly synthesized simple molecule, named TPE[double bond, length as m-dash]C4, with twisted D-A structure. TPE[double bond, length as m-dash]C4 showed two intrinsic emission bands ascribed to the locally excited (LE) state and the intramolecular charge transfer (ICT) state, respectively. In the crystal state, the LE emission band is usually observed. However, by applying hydrostatic pressure to the powder sample and the single crystal sample of TPE[double bond, length as m-dash]C4, dual-fluorescence (445 nm and 532 nm) was emerged under high pressure, owing to the pressure-induced emission band separation of the hybridized local and charge transfer excited state (HLCT). It is found that the emission of TPE[double bond, length as m-dash]C4 is generally determined by the ratio of the LE state to the ICT state. The ICT emission band is much more sensitive to the external pressure than the LE emission band. The HLCT state leads to a sample with different responsiveness to grinding and hydrostatic pressure. This study is of significance in the molecular design of such D-A type molecules and in the control of photoluminescence features by molecular structure. Such results are expected to pave a new way to further understand the relationship between the D-A molecular structure and stimuli-responsive properties.

Method and apparatus for the selective separation of gaseous coal gasification products by pressure swing adsorption

DOEpatents

Ghate, M.R.; Yang, R.T.

1985-10-03

Bulk separation of the gaseous components of multi-component gases provided by the gasification of coal including hydrogen, carbon monoxide, methane, and acid gases (carbon dioxide plus hydrogen sulfide) are selectively adsorbed by a pressure swing adsorption technique using activated carbon zeolite or a combination thereof as the adsorbent. By charging a column containing the adsorbent with a gas mixture and pressurizing the column to a pressure sufficient to cause the adsorption of the gases and then reducing the partial pressure of the contents of the column, the gases are selectively and sequentially desorbed. Hydrogen, the least absorbable gas of the gaseous mixture, is the first gas to be desorbed and is removed from the column in a co-current direction followed by the carbon monoxide, hydrogen and methane. With the pressure in the column reduced to about atmospheric pressure the column is evacuated in a countercurrent direction to remove the acid gases from the column. The present invention is particularly advantageous as a producer of high purity hydrogen from gaseous products of coal gasification and as an acid gas scrubber. 2 figs., 2 tabs.

Promotion of cooperation in evolutionary game dynamics with local information.

PubMed

Liu, Xuesong; Pan, Qiuhui; He, Mingfeng

2018-01-21

In this paper, we propose a strategy-updating rule driven by local information, which is called Local process. Unlike the standard Moran process, the Local process does not require global information about the strategic environment. By analyzing the dynamical behavior of the system, we explore how the local information influences the fixation of cooperation in two-player evolutionary games. Under weak selection, the decreasing local information leads to an increase of the fixation probability when natural selection does not favor cooperation replacing defection. In the limit of sufficiently large selection, the analytical results indicate that the fixation probability increases with the decrease of the local information, irrespective of the evolutionary games. Furthermore, for the dominance of defection games under weak selection and for coexistence games, the decreasing of local information will lead to a speedup of a single cooperator taking over the population. Overall, to some extent, the local information is conducive to promoting the cooperation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Local CO2-induced swelling of shales

NASA Astrophysics Data System (ADS)

Pluymakers, Anne; Dysthe, Dag Kristian

2017-04-01

In heterogeneous shale rocks, CO2 adsorbs more strongly to organic matter than to the other components. CO2-induced swelling of organic matter has been shown in coal, which is pure carbon. The heterogeneity of the shale matrix makes an interesting case study. Can local swelling through adsorption of CO2 to organic matter induce strain in the surrounding shale matrix? Can fractures close due to CO2-induced swelling of clays and organic matter? We have developed a new generation of microfluidic high pressure cells (up to 100 bar), which can be used to study flow and adsorption phenomena at the microscale in natural geo-materials. The devices contain one transparent side and a shale sample on the other side. The shale used is the Pomeranian shale, extracted from 4 km depth in Poland. This formation is a potential target of a combined CO2-storage and gas extraction project. To answer the first question, we place the pressure cell under a Veeco NT1100 Interferometer, operated in Vertical Scanning Interferometry mode and equipped with a Through Transmissive Media objective. This allows for observation of local swelling or organic matter with nanometer vertical resolution and micrometer lateral resolution. We expose the sample to CO2 atmospheres at different pressures. Comparison of the interferometry data and using SEM-EDS maps plus optical microscopy delivers local swelling maps where we can distinguish swelling of different mineralogies. Preliminary results indicate minor local swelling of organic matter, where the total amount is both time- and pressure-dependent.

Artificial selection on introduced Asian haplotypes shaped the genetic architecture in European commercial pigs.

PubMed

Bosse, Mirte; Lopes, Marcos S; Madsen, Ole; Megens, Hendrik-Jan; Crooijmans, Richard P M A; Frantz, Laurent A F; Harlizius, Barbara; Bastiaansen, John W M; Groenen, Martien A M

2015-12-22

Early pig farmers in Europe imported Asian pigs to cross with their local breeds in order to improve traits of commercial interest. Current genomics techniques enabled genome-wide identification of these Asian introgressed haplotypes in modern European pig breeds. We propose that the Asian variants are still present because they affect phenotypes that were important for ancient traditional, as well as recent, commercial pig breeding. Genome-wide introgression levels were only weakly correlated with gene content and recombination frequency. However, regions with an excess or absence of Asian haplotypes (AS) contained genes that were previously identified as phenotypically important such as FASN, ME1, and KIT. Therefore, the Asian alleles are thought to have an effect on phenotypes that were historically under selection. We aimed to estimate the effect of AS in introgressed regions in Large White pigs on the traits of backfat (BF) and litter size. The majority of regions we tested that retained Asian deoxyribonucleic acid (DNA) showed significantly increased BF from the Asian alleles. Our results suggest that the introgression in Large White pigs has been strongly determined by the selective pressure acting upon the introgressed AS. We therefore conclude that human-driven hybridization and selection contributed to the genomic architecture of these commercial pigs. © 2015 The Author(s).

Analysis of scale effect in compressive ice failure and implications for design

NASA Astrophysics Data System (ADS)

Taylor, Rocky Scott

The main focus of the study was the analysis of scale effect in local ice pressure resulting from probabilistic (spalling) fracture and the relationship between local and global loads due to the averaging of pressures across the width of a structure. A review of fundamental theory, relevant ice mechanics and a critical analysis of data and theory related to the scale dependent pressure behavior of ice were completed. To study high pressure zones (hpzs), data from small-scale indentation tests carried out at the NRC-IOT were analyzed, including small-scale ice block and ice sheet tests. Finite element analysis was used to model a sample ice block indentation event using a damaging, viscoelastic material model and element removal techniques (for spalling). Medium scale tactile sensor data from the Japan Ocean Industries Association (JOIA) program were analyzed to study details of hpz behavior. The averaging of non-simultaneous hpz loads during an ice-structure interaction was examined using local panel pressure data. Probabilistic averaging methodology for extrapolating full-scale pressures from local panel pressures was studied and an improved correlation model was formulated. Panel correlations for high speed events were observed to be lower than panel correlations for low speed events. Global pressure estimates based on probabilistic averaging were found to give substantially lower average errors in estimation of load compared with methods based on linear extrapolation (no averaging). Panel correlations were analyzed for Molikpaq and compared with JOIA results. From this analysis, it was shown that averaging does result in decreasing pressure for increasing structure width. The relationship between local pressure and ice thickness for a panel of unit width was studied in detail using full-scale data from the STRICE, Molikpaq, Cook Inlet and Japan Ocean Industries Association (JOIA) data sets. A distinct trend of decreasing pressure with increasing ice thickness was observed. The pressure-thickness behavior was found to be well modeled by the power law relationships Pavg = 0.278 h-0.408 MPa and Pstd = 0.172h-0.273 MPa for the mean and standard deviation of pressure, respectively. To study theoretical aspects of spalling fracture and the pressure-thickness scale effect, probabilistic failure models have been developed. A probabilistic model based on Weibull theory (tensile stresses only) was first developed. Estimates of failure pressure obtained with this model were orders of magnitude higher than the pressures observed from benchmark data due to the assumption of only tensile failure. A probabilistic fracture mechanics (PFM) model including both tensile and compressive (shear) cracks was developed. Criteria for unstable fracture in tensile and compressive (shear) zones were given. From these results a clear theoretical scale effect in peak (spalling) pressure was observed. This scale effect followed the relationship Pp,th = 0.15h-0.50 MPa which agreed well with the benchmark data. The PFM model was applied to study the effect of ice edge shape (taper angle) and hpz eccentricity. Results indicated that specimens with flat edges spall at lower pressures while those with more tapered edges spall less readily. The mean peak (failure) pressure was also observed to decrease with increased eccentricity. It was concluded that hpzs centered about the middle of the ice thickness are the zones most likely to create the peak pressures that are of interest in design. Promising results were obtained using the PFM model, which provides strong support for continued research in the development and application of probabilistic fracture mechanics to the study of scale effects in compressive ice failure and to guide the development of methods for the estimation of design ice pressures.

Plating Repair Of Nickel-Alloy Pressure Vessels

NASA Technical Reports Server (NTRS)

Ricklefs, Steve K.; Chagnon, Kevin M.

1989-01-01

Procedure for localized electrodeposition of nickel enables repair of small damaged nickel-based pressure vessels. Electrodeposition restores weakened areas of vessel wall to at least their former strength.

Pressure variations in the Monte Rosa nappe, Western Alps

NASA Astrophysics Data System (ADS)

Luisier, Cindy; Vaughan-Hammon, Joshua; Baumgartner, Lukas; Schmalholz, Stefan

2017-04-01

The Monte Rosa nappe is part of the Penninic nappe stack of the Western Alps. It represents the southern-most European continental basement involved in the alpine orogeny. It consists of a pre-Variscan basement complex, made of mostly metapelites and paragneisses, which were intruded by a Permian-age granitic body (Pawlig, 2001). The nappe is heterogeneously deformed, with localized high strain domains separating low strain domains. The metamorphic record is tightly linked to deformation. Different thermodynamic data bases and approaches were used in the past to estimate the peak alpine metamorphic conditions. They range from 1.2 to 2.7 GPa and 490 to 650˚C, based on metagranite, metapelite, metamafic and whiteschist assemblages. The peak alpine metamorphic assemblage of zoisite, phengite and albite symplectites pseudomorphing magmatic plagioclase is preserved only in the less deformed portions of the nappe. Phengite, garnet and titanite coronas surrounding biotite, quartz and igneous K-feldspar make up the rest of the rock. The metagranite locally grades into 10 to 50 meters whiteschist bodies, consisting of talc-chloritoid-kyanite-phengite-quartz, which can contain carbonate and garnet. Their chemistry is interpreted as a metasomatic product of the late magmatic hydrothermal alteration of the granite, whereas their mineralogy results from the alpine high pressure metamorphism (Pawlig and Baumgartner, 2001; Luisier et al., 2015). We performed a phase petrology and textural study to consistently estimate peak alpine metamorphic conditions in the granite and the related whiteschists. Textural observations were used to select the best-preserved high-pressure metagranite samples. Inherited magmatic feldspar textures indicate that jadeite was never formed in these granites, confirmed independently by Si in phengite barometer (1.2 to 1.5 GPa). Note that the granite contains the phengite buffer assemblage of Massonne and Schreyer (1987). Thermodynamic calculations using internally consistent thermodynamic database on whiteschists result in a minimum P of 2.2 GPa at T of 550 to 570˚C and a water activity close to 1, unlike previous water activities proposed (Le Bayon et al., 2006). Peak alpine pressures and temperatures calculated for the metagranite and associated whiteschists hence result in significant different pressure estimates, corroborating previous results from the literature. The possible explanations for such pressure variations are i) slight underestimation of the metagranite peak pressure, due to water-undersaturation conditions, however a pressure as high as 2 GPa is unlikely, or ii) heterogeneous stress conditions, due to rheologically contrasting lithologies, consisting of weak whiteschist inclusions within strong, undeformed metagranites. References Le Bayon et al., 2006: Contrib. Mineral. Petrol. 151, 395-412 Luisier et al., 2015: GSA conference abstract Massonne and Schreyer, 1987: Contrib. Mineral. Petrol. 96, 212-224 Pawlig, S. 2001: PhD thesis, University of Mainz (Germany) Pawlig and Baumgartner, 2001: SMPM 81,329-346

Genetic signature of natural selection in first Americans

PubMed Central

G. Amorim, Carlos Eduardo; Nunes, Kelly; Meyer, Diogo; Comas, David; Bortolini, Maria Cátira; Salzano, Francisco Mauro; Hünemeier, Tábita

2017-01-01

When humans moved from Asia toward the Americas over 18,000 y ago and eventually peopled the New World they encountered a new environment with extreme climate conditions and distinct dietary resources. These environmental and dietary pressures may have led to instances of genetic adaptation with the potential to influence the phenotypic variation in extant Native American populations. An example of such an event is the evolution of the fatty acid desaturases (FADS) genes, which have been claimed to harbor signals of positive selection in Inuit populations due to adaptation to the cold Greenland Arctic climate and to a protein-rich diet. Because there was evidence of intercontinental variation in this genetic region, with indications of positive selection for its variants, we decided to compare the Inuit findings with other Native American data. Here, we use several lines of evidence to show that the signal of FADS-positive selection is not restricted to the Arctic but instead is broadly observed throughout the Americas. The shared signature of selection among populations living in such a diverse range of environments is likely due to a single and strong instance of local adaptation that took place in the common ancestral population before their entrance into the New World. These first Americans peopled the whole continent and spread this adaptive variant across a diverse set of environments. PMID:28193867

Compression selective solid-state chemistry

NASA Astrophysics Data System (ADS)

Hu, Anguang

Compression selective solid-state chemistry refers to mechanically induced selective reactions of solids under thermomechanical extreme conditions. Advanced quantum solid-state chemistry simulations, based on density functional theory with localized basis functions, were performed to provide a remarkable insight into bonding pathways of high-pressure chemical reactions in all agreement with experiments. These pathways clearly demonstrate reaction mechanisms in unprecedented structural details, showing not only the chemical identity of reactive intermediates but also how atoms move along the reaction coordinate associated with a specific vibrational mode, directed by induced chemical stress occurred during bond breaking and forming. It indicates that chemical bonds in solids can break and form precisely under compression as we wish. This can be realized through strongly coupling of mechanical work to an initiation vibrational mode when all other modes can be suppressed under compression, resulting in ultrafast reactions to take place isothermally in a few femtoseconds. Thermodynamically, such reactions correspond to an entropy minimum process on an isotherm where the compression can force thermal expansion coefficient equal to zero. Combining a significantly brief reaction process with specific mode selectivity, both statistical laws and quantum uncertainty principle can be bypassed to precisely break chemical bonds, establishing fundamental principles of compression selective solid-state chemistry. Naturally this leads to understand the ''alchemy'' to purify, grow, and perfect certain materials such as emerging novel disruptive energetics.

Blue Laser Light Increases Perfusion of a Skin Flap Via Release of Nitric Oxide from Hemoglobin

PubMed Central

Mittermayr, Rainer; Osipov, Anatoly; Piskernik, Christina; Haindl, Susanne; Dungel, Peter; Weber, Carina; Vladimirov, Yuri A; Redl, Heinz; Kozlov, Andrey V

2007-01-01

It has recently been shown that nitrosyl complexes of hemoglobin (NO-Hb) are sensitive to low-level blue laser irradiation, suggesting that laser irradiation can facilitate the release of biologically active nitric oxide (NO), which can affect tissue perfusion. The aim of this study was to evaluate the therapeutic value of blue laser irradiation for local tissue perfusion after surgical intervention. Blood was withdrawn from a rat, exposed to NO and infused back to the same rat or used for in vitro experiments. In vitro, an increase of NO-Hb levels (electron paramagnetic resonance spectroscopy) up to 15 μM in rat blood did not result in the release of detectable amounts of NO (NO selective electrode). Blue laser irradiation of NO-Hb in blood caused decomposition of NO-Hb complexes and release of free NO. Systemic infusion of NO-Hb in rats affected neither systemic circulation (mean arterial pressure) nor local tissue perfusion (Doppler blood flow imaging system). In contrast, a clear enhancement of local tissue perfusion was observed in epigastric flap when elevated NO-Hb levels in blood were combined with local He-Cd laser irradiation focused on the left epigastric artery. The enhancement of regional tissue perfusion was not accompanied by any detectable changes in systemic circulation. This study demonstrates that blue laser irradiation improves local tissue perfusion in a controlled manner stimulating NO release from NO-Hb complexes. PMID:17515954

A comparison of mandibular denture base deformation with different impression techniques for implant overdentures.

PubMed

Elsyad, Moustafa Abdou; El-Waseef, Fatma Ahmad; Al-Mahdy, Yasmeen Fathy; Fouad, Mohammed Mohammed

2013-08-01

This study aimed to evaluate mandibular denture base deformation along with three impression techniques used for implant-retained overdenture. Ten edentulous patients (five men and five women) received two implants in the canine region of the mandible and three duplicate mandibular overdentures which were constructed with mucostatic, selective pressure, and definitive pressure impression techniques. Ball abutments and respective gold matrices were used to connect the overdentures to the implants. Six linear strain gauges were bonded to the lingual polished surface of each duplicate overdenture at midline and implant areas to measure strain during maximal clenching and gum chewing. The strains recorded at midline were compressive while strains at implant areas were tensile. Clenching recorded significant higher strain when compared with gum chewing for all techniques. The mucostatic technique recorded the highest strain and the definite pressure technique recorded the lowest. There was no significant difference between the strain recorded with mucostatic technique and that registered with selective pressure technique. The highest strain was recorded at the level of ball abutment's top with the mucostatic technique during clenching. Definite pressure impression technique for implant-retained mandibular overdenture is associated with minimal denture deformation during function when compared with mucostatic and selective pressure techniques. Reinforcement of the denture base over the implants may be recommended to increase resistance of fracture when mucostatic or selective pressure impression technique is used. © 2012 John Wiley & Sons A/S.

Generating a Simulated Fluid Flow Over an Aircraft Surface Using Anisotropic Diffusion

NASA Technical Reports Server (NTRS)

Rodriguez, David L. (Inventor); Sturdza, Peter (Inventor)

2013-01-01

A fluid-flow simulation over a computer-generated aircraft surface is generated using a diffusion technique. The surface is comprised of a surface mesh of polygons. A boundary-layer fluid property is obtained for a subset of the polygons of the surface mesh. A pressure-gradient vector is determined for a selected polygon, the selected polygon belonging to the surface mesh but not one of the subset of polygons. A maximum and minimum diffusion rate is determined along directions determined using a pressure gradient vector corresponding to the selected polygon. A diffusion-path vector is defined between a point in the selected polygon and a neighboring point in a neighboring polygon. An updated fluid property is determined for the selected polygon using a variable diffusion rate, the variable diffusion rate based on the minimum diffusion rate, maximum diffusion rate, and angular difference between the diffusion-path vector and the pressure-gradient vector.

There is room for selection in a small local pig breed when using optimum contribution selection: a simulation study.

PubMed

Gourdine, J L; Sørensen, A C; Rydhmer, L

2012-01-01

Selection progress must be carefully balanced against the conservation of genetic variation in small populations of local breeds. Well-defined breeding programs with specified selection traits are rare in local pig breeds. Given the small population size, the focus is often on the management of genetic diversity. However, in local breeds, optimum contribution selection can be applied to control the rate of inbreeding and to avoid reduced performance in traits with high market value. The aim of this study was to assess the extent to which a breeding program aiming for improved product quality in a small local breed would be feasible. We used stochastic simulations to compare 25 scenarios. The scenarios differed in size of population, selection intensity of boars, type of selection (random selection, truncation selection based on BLUP breeding values, or optimum contribution selection based on BLUP breeding values), and heritability of the selection trait. It was assumed that the local breed is used in an extensive system for a high-meat-quality market. The simulations showed that in the smallest population (300 female reproducers), inbreeding increased by 0.8% when selection was performed at random. With optimum contribution selection, genetic progress can be achieved that is almost as great as that with truncation selection based on BLUP breeding values (0.2 to 0.5 vs. 0.3 to 0.5 genetic SD, P < 0.05), but at a considerably decreased rate of inbreeding (0.7 to 1.2 vs. 2.3 to 5.7%, P < 0.01). This confirmation of the potential utilization of OCS even in small populations is important in the context of sustainable management and the use of animal genetic resources.

Pressure-Induced Charge-Order Melting and Reentrant Charge Carrier Localization in the Mixed-Valent Pb 3Rh 7O 15

DOE PAGES

Li, Yan; Sun, Zhao; Cai, Jia -Wei; ...

2017-07-01

Here, the mixed-valent Pbmore » $${}_{3}$$Rh $${}_{7}$$O$${}_{15}$$ undergoes a Verwey-type transition at $${T}_{{\\rm{v}}}\\approx 180$$ K, below which the development of Rh$${}^{3+}$$ /Rh$${}^{4+}$$ charge order induces an abrupt conductor-to-insulator transition in resistivity. Here we investigate the effect of pressure on the Verwey-type transition of Pb$${}_{3}$$Rh$${}_{7}$$O$${}_{15}$$ by measuring its electrical resistivity under hydrostatic pressures up to 8 GPa with a cubic anvil cell apparatus. We find that the application of high pressure can suppress the Verwey-type transition around 3 GPa, above which a metallic state is realized at temperatures below ~70 K, suggesting the melting of charge order by pressure. Interestingly, the low-temperature metallic region shrinks gradually upon further increasing pressure and disappears completely at P > 7 GPa, which indicates that the charge carriers in Pb$${}_{3}$$Rh$${}_{7}$$O$${}_{15}$$ undergo a reentrant localization under higher pressures. We have constructed a temperature-pressure phase diagram for Pb$${}_{3}$$Rh$${}_{7}$$O$${}_{15}$$ and compared to that of Fe$${}_{3}$$O$${}_{4}$$, showing an archetype Verwey transition.« less

Dynamic Dilational Strengthening During Earthquakes in Saturated Gouge-Filled Fault Zones

NASA Astrophysics Data System (ADS)

Sparks, D. W.; Higby, K.

2016-12-01

The effect of fluid pressure in saturated fault zones has been cited as an important factor in the strength and slip-stability of faults. Fluid pressure controls the effective normal stress across the fault and therefore controls the faults strength. In a fault core consisting of granular fault gouge, local transient dilations and compactions occur during slip that dynamically change the fluid pressure. We use a grain-scale numerical model to investigate the effect of these fluid effects in fault gouge during an earthquake. We use a coupled finite difference-discrete element model (Goren et al, 2011), in which the pore space is filled with a fluid. Local changes in grain packing generate local deviations in fluid pressure, which can be relieved by fluid flow through the permeable gouge. Fluid pressure gradients exert drag forces on the grains that couple the grain motion and fluid flow. We simulated 39 granular gouge zones that were slowly loaded in shear stress to near the failure point, and then conducted two different simulations starting from each grain packing: one with a high enough mean permeability (> 10-11 m2) that pressure remains everywhere equilibrated ("fully drained"), and one with a lower permeability ( 10-14 m2) in which flow is not fast enough to prevent significant pressure variations from developing ("undrained"). The static strength of the fault, the size of the event and the evolution of slip velocity are not imposed, but arise naturally from the granular packing. In our particular granular model, all fully drained slip events are well-modeled by a rapid drop in the frictional resistance of the granular packing from a static value to a dynamic value that remains roughly constant during slip. Undrained events show more complex behavior. In some cases, slip occurs via a slow creep with resistance near the static value. When rapid slip events do occur, the dynamic resistance is typically larger than in drained events, and highly variable. Frictional resistance is not correlated with the mean fluid pressure in the layer, but is instead controlled by local regions undergoing dilational strengthening. We find that (in the absence of pressure-generating effects like thermal pressurization or fluid-releasing reactions), the overall effect of fluid is to strengthen the fault.

Comparative evaluation of stress levels before, during, and after periodontal surgical procedures with and without nitrous oxide-oxygen inhalation sedation.

PubMed

Sandhu, Gurkirat; Khinda, Paramjit Kaur; Gill, Amarjit Singh; Singh Khinda, Vineet Inder; Baghi, Kamal; Chahal, Gurparkash Singh

2017-01-01

Periodontal surgical procedures produce varying degree of stress in all patients. Nitrous oxide-oxygen inhalation sedation is very effective for adult patients with mild-to-moderate anxiety due to dental procedures and needle phobia. The present study was designed to perform periodontal surgical procedures under nitrous oxide-oxygen inhalation sedation and assess whether this technique actually reduces stress physiologically, in comparison to local anesthesia alone (LA) during lengthy periodontal surgical procedures. This was a randomized, split-mouth, cross-over study. A total of 16 patients were selected for this randomized, split-mouth, cross-over study. One surgical session (SS) was performed under local anesthesia aided by nitrous oxide-oxygen inhalation sedation, and the other SS was performed on the contralateral quadrant under LA. For each session, blood samples to measure and evaluate serum cortisol levels were obtained, and vital parameters including blood pressure, heart rate, respiratory rate, and arterial blood oxygen saturation were monitored before, during, and after periodontal surgical procedures. Paired t -test and repeated measure ANOVA. The findings of the present study revealed a statistically significant decrease in serum cortisol levels, blood pressure and pulse rate and a statistically significant increase in respiratory rate and arterial blood oxygen saturation during periodontal surgical procedures under nitrous oxide inhalation sedation. Nitrous oxide-oxygen inhalation sedation for periodontal surgical procedures is capable of reducing stress physiologically, in comparison to LA during lengthy periodontal surgical procedures.

The Ring Current Response to Solar and Interplanetary Storm Drivers

NASA Astrophysics Data System (ADS)

Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

2014-12-01

The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

High-pressure studies on Ba-doped cobalt perovskites by neutron diffraction

NASA Astrophysics Data System (ADS)

Cao, Huibo; Garlea, Vasile; Wang, Fangwei; Dos Santos, Antonio; Cheng, Zhaohua

2012-02-01

Cobalt perovskite possess rich structural, magnetic and electrical properties depending on the subtle balance of the interactions among the spin, charge, and orbital degrees of freedom. Divalent hole-doped cobalt perovskites LaA^2+CoO3 exhibit structural phase transitions, metal-insulator transitions, and multi-magnetic phase transitions. High-pressure measurement is believed to mimic the size effects of the doped ions. We performed neutron diffraction experiments on selected Ba-doped LaCoO3 under pressures up to 6.3 GPa at SNAP at Spallation Neutron Source of ORNL. This work focuses on the high-pressure effects of the selected Ba-doped samples and the change of the phase diagram with pressure.

Regional cutaneous microvascular flow responses during gravitational and LBNP stresses

NASA Technical Reports Server (NTRS)

Breit, Gregory A.; Watenpaugh, Donald E.; Ballard, Richard E.; Murthy, Gita; Hargens, Alan R.

1993-01-01

Due to the regional variability of local hydrostatic pressures, microvascular flow responses to gravitational stress probably vary along the length of the body. Although these differences in local autoregulation have been observed previously during whole-body tilting, they have not been investigated during application of artificial gravitational stresses, such as lower body negative pressure or high gravity centrifugation. Although these stresses can create equivalent G-levels at the feet, they result in distinct distributions of vascular transmural pressure along the length of the body, and should consequently elicit different magnitudes and distributions of microvascular response. In the present study, the effects of whole-body tilting and lower body negative pressure on the level and distribution of microvascular flows within skin along the length of the body were compared.

Correlated topographic and structural modification on Si surface during multi-shot femtosecond laser exposures: Si nanopolymorphs as potential local structural nanomarkers

NASA Astrophysics Data System (ADS)

Ionin, A. A.; Kudryashov, S. I.; Levchenko, A. O.; Nguyen, L. V.; Saraeva, I. N.; Rudenko, A. A.; Ageev, E. I.; Potorochin, D. V.; Veiko, V. P.; Borisov, E. V.; Pankin, D. V.; Kirilenko, D. A.; Brunkov, P. N.

2017-09-01

High-pressure Si-XII and Si-III nanocrystalline polymorphs, as well as amorphous Si phase, appear consequently during multi-shot femtosecond-laser exposure of crystalline Si wafer surface above its spallation threshold along with permanently developing quasi-regular surface texture (ripples, microcones), residual hydrostatic stresses and subsurface damage, which are characterized by scanning and transmission electron microscopy, as well as by Raman micro-spectroscopy. The consequent yields of these structural Si phases indicate not only their spatially different appearance, but also potentially enable to track nanoscale, transient laser-induced high-pressure, high-temperature physical processes - local variation of ablation mechanism and rate, pressurization/pressure release, melting/resolidification, amorphization, annealing - versus cumulative laser exposure and the related development of the surface topography.

Virtual water trade patterns in relation to environmental and socioeconomic factors: A case study for Tunisia.

PubMed

Chouchane, Hatem; Krol, Maarten S; Hoekstra, Arjen Y

2018-02-01

Growing water demands put increasing pressure on local water resources, especially in water-short countries. Virtual water trade can play a key role in filling the gap between local demand and supply of water-intensive commodities. This study aims to analyse the dynamics in virtual water trade of Tunisia in relation to environmental and socio-economic factors such as GDP, irrigated land, precipitation, population and water scarcity. The water footprint of crop production is estimated using AquaCrop for six crops over the period 1981-2010. Net virtual water import (NVWI) is quantified at yearly basis. Regression models are used to investigate dynamics in NVWI in relation to the selected factors. The results show that NVWI during the study period for the selected crops is not influenced by blue water scarcity. NVWI correlates in two alternative models to either population and precipitation (model I) or to GDP and irrigated area (model II). The models are better in explaining NVWI of staple crops (wheat, barley, potatoes) than NVWI of cash crops (dates, olives, tomatoes). Using model I, we are able to explain both trends and inter-annual variability for rain-fed crops. Model II performs better for irrigated crops and is able to explain trends significantly; no significant relation is found, however, with variables hypothesized to represent inter-annual variability. Copyright © 2017 Elsevier B.V. All rights reserved.

Noncontact Measurement of the Local Mechanical Properties of Living Cells Using Pressure Applied via a Pipette

PubMed Central

Sánchez, Daniel; Johnson, Nick; Li, Chao; Novak, Pavel; Rheinlaender, Johannes; Zhang, Yanjun; Anand, Uma; Anand, Praveen; Gorelik, Julia; Frolenkov, Gregory I.; Benham, Christopher; Lab, Max; Ostanin, Victor P.; Schäffer, Tilman E.; Klenerman, David; Korchev, Yuri E.

2008-01-01

Mechanosensitivity in living biological tissue is a study area of increasing importance, but investigative tools are often inadequate. We have developed a noncontact nanoscale method to apply quantified positive and negative force at defined positions to the soft responsive surface of living cells. The method uses applied hydrostatic pressure (0.1–150 kPa) through a pipette, while the pipette-sample separation is kept constant above the cell surface using ion conductance based distance feedback. This prevents any surface contact, or contamination of the pipette, allowing repeated measurements. We show that we can probe the local mechanical properties of living cells using increasing pressure, and hence measure the nanomechanical properties of the cell membrane and the underlying cytoskeleton in a variety of cells (erythrocytes, epithelium, cardiomyocytes and neurons). Because the cell surface can first be imaged without pressure, it is possible to relate the mechanical properties to the local cell topography. This method is well suited to probe the nanomechanical properties and mechanosensitivity of living cells. PMID:18515369

Electronic and local atomistic structure of MgSiO3 glass under pressure: a study of X-ray Raman scattering at the silicon and magnesium L-edges

NASA Astrophysics Data System (ADS)

Fukui, Hiroshi; Hiraoka, Nozomu

2018-02-01

We applied X-ray Raman scattering technique to MgSiO3 glass, a precursor to magnesium silicate melts, with respect to magnesium and silicon under high-pressure conditions as well as some polycrystalline phases of MgSiO3 at ambient conditions. We also performed ab initio calculations to interpret the X-ray Raman spectra. Experimentally obtained silicon L-edge spectra indicate that the local environment around silicon started changing at pressure above 10 GPa, where the electronic structure of oxygen is known to change. In contrast, the shape of the magnesium L-edge spectrum changed below 10 GPa. This indicates that the magnesium sites in MgSiO3 glass first distort and that the local structure around magnesium shows a wide variation under pressure. The framework structure consisting of silicon and oxygen changed above 10 GPa, where the coordination number of silicon was more than four. Our results imply that 6-oxygen-coordinated silicon was formed above 20 GPa.

Room-temperature ionic liquids: slow dynamics, viscosity, and the red edge effect.

PubMed

Hu, Zhonghan; Margulis, Claudio J

2007-11-01

Ionic liquids (ILs) have recently attracted significant attention from academic and industrial sources. This is because, while their vapor pressures are negligible, many of them are liquids at room temperature and can dissolve a wide range of polar and nonpolar organic and inorganic molecules. In this Account, we discuss the progress of our laboratory in understanding the dynamics, spectroscopy, and fluid dynamics of selected imidazolium-based ILs using computational and analytical tools that we have recently developed. Our results indicate that the red edge effect, the non-Newtonian behavior, and the existence of locally heterogeneous environments on a time scale relevant to chemical and photochemical reactivity are closely linked to the viscosity and highly structured character of these liquids.

Condensation Front Migration in a Protoplanetary Nebula

NASA Technical Reports Server (NTRS)

Davis, Sanford S.

2004-01-01

Condensation front dynamics are investigated in the mid-solar nebula region. A quasi-steady model of the evolving nebula is combined with equilibrium vapor pressure curves to determine evolutionary condensation fronts for selected species. These fronts are found to migrate inwards from the far-nebula to final positions during a period of 10(exp 7) years. The physical process governing this movement is a combination of local viscous heating and luminescent heating from the central star. Two luminescent heating models are used and their effects on the ultimate radial position of the condensation front are discussed. At first the fronts move much faster than the nebular accretion velocity, but after a time the accreting gas and dust overtakes the slowing condensation front.

Nebulized antibiotics. An adequate option for treating ventilator-associated respiratory infection?

PubMed

Rodríguez, A; Barcenilla, F

2015-03-01

Ventilator-associated tracheobronchitis (VAT) is a frequent complication in critical patients. The 90% of those who develop it receive broad-spectrum antibiotic (ATB) treatment, without any strong evidence of its favorable impact. The use of nebulized ATB could be a valid treatment option, to reduce the use of systemic ATB and the pressure of selection on the local flora. Several studies suggest that an adequate nebulization technique can ensure high levels of ATB even in areas of lung consolidation, and to obtain clinical and microbiological cure. New studies are needed to properly assess the impact of treatment with nebulized ATB on the emergence of resistance. Copyright © 2014 Elsevier España, S.L.U. y SEMICYUC. All rights reserved.

Appalachian spring: variations on ancient gastro-entero-pancreatic themes in New World mammals.

PubMed

Seino, S; Blackstone, C D; Chan, S J; Whittaker, J; Bell, G I; Steiner, D F

1988-07-01

Studies of guinea pig genomic and/or cDNA clones encoding the gastro-entero-pancreatic (GEP) hormones--insulin, glucagon and pancreatic polypeptide--as well as portions of the insulin receptor, are described. Multiple clustered substitutions (localized rapid mutation acceptance) altering the biological properties of both insulin and glucagon have been revealed, but this does not appear to be the case with either pancreatic polypeptide or those regions of guinea pig insulin receptor cDNAs that have been examined thus far. These findings suggest that novel selective pressures operative in the New World environment, in which these animals evolved in isolation from Old World mammalian species, have led to altered solutions to problems related to the regulation of growth and carbohydrate metabolism.

Properties of the tick-borne encephalitis virus population during persistent infection of ixodid ticks and tick cell lines.

PubMed

Belova, Oxana A; Litov, Alexander G; Kholodilov, Ivan S; Kozlovskaya, Liubov I; Bell-Sakyi, Lesley; Romanova, Lidiya Iu; Karganova, Galina G

2017-10-01

Tick-borne encephalitis virus (TBEV) is the causative agent of tick-borne encephalitis (TBE), a vector-borne zoonotic neuroinfection. For successful circulation in natural foci the virus has to survive in the vector for a long period of time. Information about the effect of long-term infection of ticks on properties of the viral population is of great importance. In recent years, changes in the eco-epidemiology of TBEV due to changes in distribution of ixodid ticks have been observed. These changes in TBEV-endemic areas could result in a shift of the main tick vector species, which in turn may lead to changes in properties of the virus. In the present study we evaluated the selective pressure on the TBEV population during persistent infection of various species of ticks and tick cell lines. TBEV effectively replicated and formed persistent infection in ticks and tick cell lines of the vector species (Ixodes spp.), potential vectors (Dermacentor spp.) and non-vector ticks (Hyalomma spp.). During TBEV persistence in Ixodes and Dermacentor ticks, properties of the viral population remained virtually unchanged. In contrast, persistent TBEV infection of tick cell lines from both vector and non-vector ticks favoured selection of viral variants with low neuroinvasiveness for laboratory mice and substitutions in the E protein that increased local positive charge of the virion. Thus, selective pressure on viral population may differ in ticks and tick cell lines during persistent infection. Nevertheless, virus variants with properties of the original strain adapted to mouse CNS were not eliminated from the viral population during long-term persistence of TBEV in ticks and tick cell lines. Copyright © 2017 Elsevier GmbH. All rights reserved.

Fission yeast Ags1 confers the essential septum strength needed for safe gradual cell abscission

PubMed Central

Sato, Mamiko; Muñoz, Javier; Moreno, M. Belén; Clemente-Ramos, Jose Angel; Ramos, Mariona; Okada, Hitoshi; Osumi, Masako; Durán, Angel; Ribas, Juan Carlos

2012-01-01

Fungal cytokinesis requires the assembly of a dividing septum wall. In yeast, the septum has to be selectively digested during the critical cell separation process. Fission yeast cell wall α(1-3)glucan is essential, but nothing is known about its localization and function in the cell wall or about cooperation between the α- and β(1-3)glucan synthases Ags1 and Bgs for cell wall and septum assembly. Here, we generate a physiological Ags1-GFP variant and demonstrate a tight colocalization with Bgs1, suggesting a cooperation in the important early steps of septum construction. Moreover, we define the essential functions of α(1-3)glucan in septation and cell separation. We show that α(1-3)glucan is essential for both secondary septum formation and the primary septum structural strength needed to support the physical forces of the cell turgor pressure during cell separation. Consequently, the absence of Ags1 and therefore α(1-3)glucan generates a special and unique side-explosive cell separation due to an instantaneous primary septum tearing caused by the turgor pressure. PMID:22891259

Corticotropin-releasing factor stimulates colonic motility via muscarinic receptors in the rat

PubMed Central

Kim, Kyung-Jo; Kim, Ki Bae; Yoon, Soon Man; Han, Joung-Ho; Chae, Hee Bok; Park, Seon Mee; Youn, Sei Jin

2017-01-01

AIM To measure exogenous corticotropin-releasing factor (CRF)-induced motility of the isolated rat colon and to demonstrate the effect of pharmacologic inhibition on CRF-induced motility. METHODS The isolated vascularly-perfused rat colon was used. Luminal pressure was monitored via microtip catheter pressure transducers in the proximal and distal colon. At first, exogenous CRF was administered in a stepwise manner and the concentration of CRF yielding maximal colonic motility was selected. After recording basal colonic motility, hexamethonium, phentolamine, propranolol, atropine and tetrodotoxin were infused into the isolated colon. Initially, only the test drug was infused; then, CRF was added. The motility index was expressed as percentage change over basal level. RESULTS Administration of 1.4, 14.4, 144 and 288 pmol/L CRF progressively increased colonic motility in the proximal and distal colon. Infusion of atropine or tetrodotoxin reduced CRF-induced motility of both the proximal and distal colon, whereas hexamethonium, phentolamine and propranolol had no effect. CONCLUSION CRF-induced colonic motility appears to be mediated by local cholinergic signaling via muscarinic receptors. Muscarinic receptors are potential targets for counteracting CRF-induced colonic hypermotility. PMID:28638222

Self-actuated shutdown system for a commercial size LMFBR. Final report

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

Dupen, C.F.G.

1978-08-01

A Self-Actuated Shutdown System (SASS) is defined as a reactor shutdown system in which sensors, release mechanisms and neutron absorbers are contained entirely within the reactor core structure, where they respond inherently to abnormal local process conditions, by shutting down the reactor, independently of the plant protection system (PPS). It is argued that a SASS, having a response time similar to that of the PPS, would so reduce the already very low probability of a failure-to-scram event that costly design features, derived from core disruptive accident analysis, could be eliminated. However, the thrust of the report is the feasibility andmore » reliability of the in-core SASS hardware to achieve sufficiently rapid shutdown. A number of transient overpower and transient undercooling-responsive systems were investigated leading to the selection of a primary candidate and a backup concept. During a transient undercooling event, the recommended device is triggered by the associated rate of change of pressure, whereas the alternate concept responds to the reduction in core pressure drop and requires calibration and adjustment by the operators to accommodate changes in reactor power.« less

Material characterization of a novel new armour steel

NASA Astrophysics Data System (ADS)

Bester, J. N.; Stumpf, W. E.

2012-08-01

The material characterization of a novel new armour steel with comparison to a leading commercial benchmark alloy is presented. Direct ballistic and experimental comparison is drawn. The 5.56 × 45 mm [M193] and 7.62 × 51 mm [NATO Ball] projectiles were used in a cartridge type high pressure barrel configuration to evaluate the superior plugging resistance of the new steel over a range of plate thicknesses. To characterize the dynamic plasticity of the materials, quasi-static, notched and high temperature tensile tests as well as Split Hopkinson Pressure Bar tests in tension and compression were performed. The open source explicit solver, IMPACT (sourceforge.net) is used in an ongoing numerical and sensitivity analysis of ballistic impact. A simultaneous multi variable fitting algorithm is planned to evaluate several selected numerical material models and show their relative correlation to experimental data. This study as well as micro-metallurgical investigation of adiabatic shear bands and localized deformation zones should result in new insights in to the underlying metallurgical and physical behavior of armour plate steels during ballistic perforation.

ANALYSIS OF SELECTED PYRETHROID PESTICIDES USING REVERSE PHASE HIGH PRESSURE LIQUID CHROMATOGRAPHY/UV

EPA Science Inventory

This research was conducted in cooperation with EPA Region 4 in Athens, GA to develop a method to analyze selected pyrethroid pesticides using Reverse Phase-High Pressure Liquid Chromatography (HPLC). This HPLC method will aid researchers in separating and identifying these py...

Determination of Polychlorinated Biphenyls in Soil and Sediment by Selective Pressurized Liquid Extraction with Immunochemical Detection

EPA Science Inventory

A selective liquid pressurized extraction (SPLE) method was developed as a streamlined sample preparation/cleanup procedure for determining Aroclors and coplanar polychlorinated biphenyls (PCBs) in soil and sediment matrices. The SPLE method was coupled with an enzyme-linked imm...

Measurements of surface-pressure fluctuations on the XB-70 airplane at local Mach numbers up to 2.45

NASA Technical Reports Server (NTRS)

Lewis, T. L.; Dods, J. B., Jr.; Hanly, R. D.

1973-01-01

Measurements of surface-pressure fluctuations were made at two locations on the XB-70 airplane for nine flight-test conditions encompassing a local Mach number range from 0.35 to 2.45. These measurements are presented in the form of estimated power spectral densities, coherence functions, and narrow-band-convection velocities. The estimated power spectral densities compared favorably with wind-tunnel data obtained by other experimenters. The coherence function and convection velocity data supported conclusions by other experimenters that low-frequency surface-pressure fluctuations consist of small-scale turbulence components with low convection velocity.

On-line calibration of high-response pressure transducers during jet-engine testing

NASA Technical Reports Server (NTRS)

Armentrout, E. C.

1974-01-01

Jet engine testing is reported concerned with the effect of inlet pressure and temperature distortions on engine performance and involves the use of numerous miniature pressure transducers. Despite recent improvements in the manufacture of miniature pressure transducers, they still exhibit sensitivity change and zero-shift with temperature and time. To obtain meaningful data, a calibration system is needed to determine these changes. A system has been developed which provides for computer selection of appropriate reference pressures selected from nine different sources to provide a two- or three-point calibration. Calibrations are made on command, before and sometimes after each data point. A unique no leak matrix valve design is used in the reference pressure system. Zero-shift corrections are measured and the values are automatically inserted into the data reduction program.

Evolutionary stasis in Euphorbiaceae pollen: selection and constraints.

PubMed

Matamoro-Vidal, A; Furness, C A; Gouyon, P-H; Wurdack, K J; Albert, B

2012-06-01

Although much attention has been paid to the role of stabilizing selection, empirical analyses testing the role of developmental constraints in evolutionary stasis remain rare, particularly for plants. This topic is studied here with a focus on the evolution of a pollen ontogenetic feature, the last points of callose deposition (LPCD) pattern, involved in the determination of an adaptive morphological pollen character (aperture pattern). The LPCD pattern exhibits a low level of evolution in eudicots, as compared to the evolution observed in monocots. Stasis in this pattern might be explained by developmental constraints expressed during male meiosis (microsporogenesis) or by selective pressures expressed through the adaptive role of the aperture pattern. Here, we demonstrate that the LPCD pattern is conserved in Euphorbiaceae s.s. and that this conservatism is primarily due to selective pressures. A phylogenetic association was found between the putative removal of selective pressures on pollen morphology after the origin of inaperturate pollen, and the appearance of variation in microsporogenesis and in the resulting LPCD pattern, suggesting that stasis was due to these selective pressures. However, even in a neutral context, variation in microsporogenesis was biased. This should therefore favour the appearance of some developmental and morphological phenotypes rather than others. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

Network rigidity and properties of SiO2 and GeO2 glasses under pressure.

PubMed

Trachenko, Kostya; Dove, Martin T; Brazhkin, Vadim; El'kin, F S

2004-09-24

We report in situ studies of SiO2 glass under pressure and find that temperature-induced densification takes place in a pressure window. To explain this effect, we study how rigidity of glasses changes under pressure, with rigidity percolation affecting the dynamics of local relaxation events. We link rigidity percolation in glasses to other effects, including a large increase of crystallization temperature and logarithmic relaxation under pressure.

Automatic transducer switching provides accurate wide range measurement of pressure differential

NASA Technical Reports Server (NTRS)

Yoder, S. K.

1967-01-01

Automatic pressure transducer switching network sequentially selects any one of a number of limited-range transducers as gas pressure rises or falls, extending the range of measurement and lessening the chances of damage due to high pressure.

Reduced Lung Cancer Mortality With Lower Atmospheric Pressure.

PubMed

Merrill, Ray M; Frutos, Aaron

2018-01-01

Research has shown that higher altitude is associated with lower risk of lung cancer and improved survival among patients. The current study assessed the influence of county-level atmospheric pressure (a measure reflecting both altitude and temperature) on age-adjusted lung cancer mortality rates in the contiguous United States, with 2 forms of spatial regression. Ordinary least squares regression and geographically weighted regression models were used to evaluate the impact of climate and other selected variables on lung cancer mortality, based on 2974 counties. Atmospheric pressure was significantly positively associated with lung cancer mortality, after controlling for sunlight, precipitation, PM2.5 (µg/m 3 ), current smoker, and other selected variables. Positive county-level β coefficient estimates ( P < .05) for atmospheric pressure were observed throughout the United States, higher in the eastern half of the country. The spatial regression models showed that atmospheric pressure is positively associated with age-adjusted lung cancer mortality rates, after controlling for other selected variables.

Investigation of jet exhaust and local Mach number effects on the Solid Rocket Booster (SRB) base pressures (fa19)

NASA Technical Reports Server (NTRS)

Love, D. A.

1978-01-01

Two single nozzles with flare angles of 10 and 20 degrees were tested at Mach numbers of 0.5, 0.9, 1.2, 1.46, 1.96 and 3.48 in the presence of gaseous plumes. An attempt was made to determine the local Mach number above the flare by utilizing a pitot probe. This objective was only partially satisfied because the 20 degree flare separated the flow ahead of the flare for Mach numbers of 0.5 to 1.96. An accurate local Mach number could not be determined because of the separated flow. To meet the objective of a data base as a function of freestream Mach number, model surface and base pressures were obtained in the presence of gaseous plumes for a matrix of chamber pressures and temperatures at Mach numbers of 0.5, 0.9, 1.2, 1.46, 1.96 and 3.48.

Subtle differences in selective pressures applied on the envelope gene of HIV-1 in pregnant versus non-pregnant women.

PubMed

Ransy, Doris G; Lord, Etienne; Caty, Martine; Lapointe, Normand; Boucher, Marc; Diallo, Abdoulaye Baniré; Soudeyns, Hugo

2018-04-17

Pregnancy is associated with modulations of maternal immunity that contribute to foeto-maternal tolerance. To understand whether and how these alterations impact antiviral immunity, a detailed cross-sectional analysis of selective pressures exerted on HIV-1 envelope amino-acid sequences was performed in a group of pregnant (n = 32) and non-pregnant (n = 44) HIV-infected women in absence of treatment with antiretroviral therapy (ART). Independent of HIV-1 subtype, p-distance, dN and dS were all strongly correlated with one another but were not significantly different in pregnant as compared to non-pregnant patients. Differential levels of selective pressure applied on different Env subdomains displayed similar yet non-identical patterns between the two groups, with pressure applied on C1 being significantly lower in constant regions C1 and C2 than in V1, V2, V3 and C3. To draw a general picture of the selection applied on the envelope and compensate for inter-individual variations, we performed a binomial test on selection frequency data pooled from pregnant and non-pregnant women. This analysis uncovered 42 positions, present in both groups, exhibiting statistically-significant frequency of selection that invariably mapped to the surface of the Env protein, with the great majority located within epitopes recognized by Env-specific antibodies or sites associated with the development of cross-reactive neutralizing activity. The median frequency of occurrence of positive selection per site was significantly lower in pregnant versus non-pregnant women. Furthermore, examination of the distribution of positively selected sites using a hypergeometric test revealed that only 2 positions (D137 and S142) significantly differed between the 2 groups. Taken together, these result indicate that pregnancy is associated with subtle yet distinctive changes in selective pressures exerted on the HIV-1 Env protein that are compatible with transient modulations of maternal immunity. Copyright © 2018 Elsevier B.V. All rights reserved.

49 CFR 192.181 - Distribution line valves.

Code of Federal Regulations, 2010 CFR

2010-10-01

... line valves. (a) Each high-pressure distribution system must have valves spaced so as to reduce the... pressure, the size of the mains, and the local physical conditions. (b) Each regulator station controlling the flow or pressure of gas in a distribution system must have a valve installed on the inlet piping...

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate.

PubMed

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-06-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal.

Impacts of invasive fish removal through angling on population characteristics and juvenile growth rate

PubMed Central

Evangelista, Charlotte; Britton, Robert J; Cucherousset, Julien

2015-01-01

Exploitation can modify the characteristics of fish populations through the selective harvesting of individuals, with this potentially leading to rapid ecological and evolutionary changes. Despite the well-known effects of invasive fishes on aquatic ecosystems generally, the potential effects of their selective removal through angling, a strategy commonly used to manage invasive fish, are poorly understood. The aim of this field-based study was to use the North American pumpkinseed Lepomis gibbosus as the model species to investigate the consequences of selective removal on their population characteristics and juvenile growth rates across 10 populations in artificial lakes in southern France. We found that the maximal individual mass in populations decreased as removal pressure through angling increased, whereas we did not observed any changes in the maximal individual length in populations as removal pressure increased. Total population abundance did not decrease as removal pressure increased; instead, here was a U-shaped relationship between removal pressure and the abundance of medium-bodied individuals. In addition, population biomass had a U-shaped curve response to removal pressure, implying that invasive fish populations can modulate their characteristics to compensate for the negative effects of selective removals. In addition, individual lengths at age 2 and juvenile growth rates decreased as removal pressure through angling increased, suggesting a shift toward an earlier size at maturity and an overall slower growing phenotype. Therefore, these outputs challenge the efficiency of selective management methods, suggesting the use of more proactive strategies to control invasive populations, and the need to investigate the potential ecological and evolutionary repercussions of nonrandom removal. PMID:26078856

Fast and behavior-selective exploitation of a marine fish targeted by anglers

PubMed Central

Alós, Josep; Palmer, Miquel; Rosselló, Rosario; Arlinghaus, Robert

2016-01-01

Harvesting of wild-living animals is often intensive and may selectively target heritable behavioral traits. We studied the exploitation dynamics and the vulnerability consequences of individual heterogeneity in movement-related behaviors in free-ranging pearly razorfish (Xyrichthys novacula). Using underwater-video recording, we firstly document a fast and high exploitation rate of about 60% of the adult population removed in just few days after the opening of the season. Subsequently, we tagged a sample of individuals with acoustic transmitters and studied whether behavioral traits were significant predictors of the vulnerability to angling. Tagged individuals revealed repeatable behaviors in several home range-related traits, suggesting the presence of spatial behavioral types. The individuals surviving the experimental fishery showed only localized and low-intensity movement patterns. Our study provides new insights for understanding the harvesting pressures and selective properties acting on behavioral traits of recreational fishing. Many fish stocks around the globe are today predominantly exploited by recreational fisheries. The fisheries-induced change in fish behavior described here may be therefore widespread, and has the potential to alter food-webs, profitability of the fisheries and to affect stock assessment by eroding catchability in the long-term. PMID:27922022

Chemical and morphological characteristics of new clones and commercial varieties of globe artichoke (Cynara cardunculus var. scolymus).

PubMed

Pandino, Gaetano; Lombardo, Sara; Mauromicale, Giovanni

2011-09-01

The globe artichoke is a widely consumed vegetable in the Mediterranean Basin, with Italy being the leading producer. In southern Italy, its cultivation contributes to local economic stability and social development. The producers are increasingly choosing to replace autochthonous varieties, such as 'Violetto di Sicilia', with cultivars bred or selected outside of the region, putting pressure on the maintenance of traditional varieties. Here, we have undertaken a detailed morphological and chemical analysis of a group of clones selected from a population of 'Violetto di Sicilia'. All the traits measured displayed genetic variation, particularly the total content of phenolics and minerals. The capitula of the 'Violetto di Sicilia' clones contained, on average, 6.3 g kg(-1) of fresh weight total phenolics, compared with 4.5 g kg(-1) in the two commercial varieties. The clones also had more inulin than commercial varieties (254 vs. 225 g kg(-1) of dry matter), as well as a good mineral content. The set of clones is of interest in the context of the proposed improvement of the crop through breeding and selection of genotypes with high nutritional quality and a specific end-use (industrial processing or fresh consumption).

Frequency-dependent selection can lead to evolution of high mutation rates.

PubMed

Rosenbloom, Daniel I S; Allen, Benjamin

2014-05-01

Theoretical and experimental studies have shown that high mutation rates can be advantageous, especially in novel or fluctuating environments. Here we examine how frequency-dependent competition may lead to fluctuations in trait frequencies that exert upward selective pressure on mutation rates. We use a mathematical model to show that cyclical trait dynamics generated by "rock-paper-scissors" competition can cause the mutation rate in a population to converge to a high evolutionarily stable mutation rate, reflecting a trade-off between generating novelty and reproducing past success. Introducing recombination lowers the evolutionarily stable mutation rate but allows stable coexistence between mutation rates above and below the evolutionarily stable rate. Even considering strong mutational load and ignoring the costs of faithful replication, evolution favors positive mutation rates if the selective advantage of prevailing in competition exceeds the ratio of recombining to nonrecombining offspring. We discuss a number of genomic mechanisms that may meet our theoretical requirements for the adaptive evolution of mutation. Overall, our results suggest that local mutation rates may be higher on genes influencing cyclical competition and that global mutation rates in asexual species may be higher in populations subject to strong cyclical competition.

Fast and behavior-selective exploitation of a marine fish targeted by anglers

NASA Astrophysics Data System (ADS)

Alós, Josep; Palmer, Miquel; Rosselló, Rosario; Arlinghaus, Robert

2016-12-01

Harvesting of wild-living animals is often intensive and may selectively target heritable behavioral traits. We studied the exploitation dynamics and the vulnerability consequences of individual heterogeneity in movement-related behaviors in free-ranging pearly razorfish (Xyrichthys novacula). Using underwater-video recording, we firstly document a fast and high exploitation rate of about 60% of the adult population removed in just few days after the opening of the season. Subsequently, we tagged a sample of individuals with acoustic transmitters and studied whether behavioral traits were significant predictors of the vulnerability to angling. Tagged individuals revealed repeatable behaviors in several home range-related traits, suggesting the presence of spatial behavioral types. The individuals surviving the experimental fishery showed only localized and low-intensity movement patterns. Our study provides new insights for understanding the harvesting pressures and selective properties acting on behavioral traits of recreational fishing. Many fish stocks around the globe are today predominantly exploited by recreational fisheries. The fisheries-induced change in fish behavior described here may be therefore widespread, and has the potential to alter food-webs, profitability of the fisheries and to affect stock assessment by eroding catchability in the long-term.

Sensitivity Analysis of the Static Aeroelastic Response of a Wing

NASA Technical Reports Server (NTRS)

Eldred, Lloyd B.

1993-01-01

A technique to obtain the sensitivity of the static aeroelastic response of a three dimensional wing model is designed and implemented. The formulation is quite general and accepts any aerodynamic and structural analysis capability. A program to combine the discipline level, or local, sensitivities into global sensitivity derivatives is developed. A variety of representations of the wing pressure field are developed and tested to determine the most accurate and efficient scheme for representing the field outside of the aerodynamic code. Chebyshev polynomials are used to globally fit the pressure field. This approach had some difficulties in representing local variations in the field, so a variety of local interpolation polynomial pressure representations are also implemented. These panel based representations use a constant pressure value, a bilinearly interpolated value. or a biquadraticallv interpolated value. The interpolation polynomial approaches do an excellent job of reducing the numerical problems of the global approach for comparable computational effort. Regardless of the pressure representation used. sensitivity and response results with excellent accuracy have been produced for large integrated quantities such as wing tip deflection and trim angle of attack. The sensitivities of such things as individual generalized displacements have been found with fair accuracy. In general, accuracy is found to be proportional to the relative size of the derivatives to the quantity itself.

A Two-Step Method to Select Major Surge-Producing Extratropical Cyclones from a 10,000-Year Stochastic Catalog

NASA Astrophysics Data System (ADS)

Keshtpoor, M.; Carnacina, I.; Yablonsky, R. M.

2016-12-01

Extratropical cyclones (ETCs) are the primary driver of storm surge events along the UK and northwest mainland Europe coastlines. In an effort to evaluate the storm surge risk in coastal communities in this region, a stochastic catalog is developed by perturbing the historical storm seeds of European ETCs to account for 10,000 years of possible ETCs. Numerical simulation of the storm surge generated by the full 10,000-year stochastic catalog, however, is computationally expensive and may take several months to complete with available computational resources. A new statistical regression model is developed to select the major surge-generating events from the stochastic ETC catalog. This regression model is based on the maximum storm surge, obtained via numerical simulations using a calibrated version of the Delft3D-FM hydrodynamic model with a relatively coarse mesh, of 1750 historical ETC events that occurred over the past 38 years in Europe. These numerically-simulated surge values were regressed to the local sea level pressure and the U and V components of the wind field at the location of 196 tide gauge stations near the UK and northwest mainland Europe coastal areas. The regression model suggests that storm surge values in the area of interest are highly correlated to the U- and V-component of wind speed, as well as the sea level pressure. Based on these correlations, the regression model was then used to select surge-generating storms from the 10,000-year stochastic catalog. Results suggest that roughly 105,000 events out of 480,000 stochastic storms are surge-generating events and need to be considered for numerical simulation using a hydrodynamic model. The selected stochastic storms were then simulated in Delft3D-FM, and the final refinement of the storm population was performed based on return period analysis of the 1750 historical event simulations at each of the 196 tide gauges in preparation for Delft3D-FM fine mesh simulations.

Evaluation of surgical procedure selection based on intraoperative free portal pressure measurement in patients with portal hypertension.

PubMed

Sun, Yong-Wei; Chen, Wei; Luo, Meng; Hua, Rong; Liu, Wei; Huo, Yan-Miao; Wu, Zhi-Yong; Cao, Hui

2010-06-01

Various surgical procedures can be used to treat liver cirrhosis and portal hypertension. How to select the most appropriate procedure for patients with portal hypertension has become a difficult problem. This study aimed to analyze the relationship between the value of intraoperative free portal pressure (FPP) and postoperative complications, and to explore the significance of intraoperative FPP measurement with respect to surgical procedure selection. The clinical data of 187 patients with portal hypertension who received pericardial devascularization and proximal splenorenal shunt combined with devascularization (combined operation) at the Department of General Surgery in our hospital from January 2001 to September 2008 were retrospectively analyzed. Among the patients who received pericardial devascularization, those with a postoperative FPP >or=22 mmHg were included in a high-pressure group (n=68), and those with FPP <22 mmHg were in a low-pressure group (n=49). Seventy patients who received the combined operation comprised a combined group. The intraoperative FPP measurement changes at different times, and the incidence of postoperative complications in the three groups of patients were compared. The postoperative FPP value in the high-pressure group was 27.5+/-2.3 mmHg, which was significantly higher than that of the low-pressure (20.9+/-1.8 mmHg) or combined groups (21.7+/-2.5 mmHg). The rebleeding rate in the high-pressure group was significantly higher than that in the low-pressure and combined groups. The incidence rates of postoperative hepatic encephalopathy and liver failure were not statistically different among the three groups. The mortality due to rebleeding in the low-pressure and combined groups (0.84%) was significantly lower than that of the high-pressure group. The study demonstrates that FPP is a critical measurement for surgical procedure selection in patients with portal hypertension. A FPP value >or=22 mmHg after splenectomy and devascularization alone is an important indicator that an additional proximal splenorenal shunt needs to be performed.

Genomic Comparison of Indigenous African and Northern European Chickens Reveals Putative Mechanisms of Stress Tolerance Related to Environmental Selection Pressure

PubMed Central

Fleming, Damarius S.; Weigend, Steffen; Simianer, Henner; Weigend, Annett; Rothschild, Max; Schmidt, Carl; Ashwell, Chris; Persia, Mike; Reecy, James; Lamont, Susan J.

2017-01-01

Global climate change is increasing the magnitude of environmental stressors, such as temperature, pathogens, and drought, that limit the survivability and sustainability of livestock production. Poultry production and its expansion is dependent upon robust animals that are able to cope with stressors in multiple environments. Understanding the genetic strategies that indigenous, noncommercial breeds have evolved to survive in their environment could help to elucidate molecular mechanisms underlying biological traits of environmental adaptation. We examined poultry from diverse breeds and climates of Africa and Northern Europe for selection signatures that have allowed them to adapt to their indigenous environments. Selection signatures were studied using a combination of population genomic methods that employed FST, integrated haplotype score (iHS), and runs of homozygosity (ROH) procedures. All the analyses indicated differences in environment as a driver of selective pressure in both groups of populations. The analyses revealed unique differences in the genomic regions under selection pressure from the environment for each population. The African chickens showed stronger selection toward stress signaling and angiogenesis, while the Northern European chickens showed more selection pressure toward processes related to energy homeostasis. The results suggest that chromosomes 2 and 27 are the most diverged between populations and the most selected upon within the African (chromosome 27) and Northern European (chromosome 2) birds. Examination of the divergent populations has provided new insight into genes under possible selection related to tolerance of a population’s indigenous environment that may be baselines for examining the genomic contribution to tolerance adaptions. PMID:28341699

Genomic Comparison of Indigenous African and Northern European Chickens Reveals Putative Mechanisms of Stress Tolerance Related to Environmental Selection Pressure.

PubMed

Fleming, Damarius S; Weigend, Steffen; Simianer, Henner; Weigend, Annett; Rothschild, Max; Schmidt, Carl; Ashwell, Chris; Persia, Mike; Reecy, James; Lamont, Susan J

2017-05-05

Global climate change is increasing the magnitude of environmental stressors, such as temperature, pathogens, and drought, that limit the survivability and sustainability of livestock production. Poultry production and its expansion is dependent upon robust animals that are able to cope with stressors in multiple environments. Understanding the genetic strategies that indigenous, noncommercial breeds have evolved to survive in their environment could help to elucidate molecular mechanisms underlying biological traits of environmental adaptation. We examined poultry from diverse breeds and climates of Africa and Northern Europe for selection signatures that have allowed them to adapt to their indigenous environments. Selection signatures were studied using a combination of population genomic methods that employed F ST , integrated haplotype score (iHS), and runs of homozygosity (ROH) procedures. All the analyses indicated differences in environment as a driver of selective pressure in both groups of populations. The analyses revealed unique differences in the genomic regions under selection pressure from the environment for each population. The African chickens showed stronger selection toward stress signaling and angiogenesis, while the Northern European chickens showed more selection pressure toward processes related to energy homeostasis. The results suggest that chromosomes 2 and 27 are the most diverged between populations and the most selected upon within the African (chromosome 27) and Northern European (chromosome 2) birds. Examination of the divergent populations has provided new insight into genes under possible selection related to tolerance of a population's indigenous environment that may be baselines for examining the genomic contribution to tolerance adaptions. Copyright © 2017 Fleming et al.

Censorship in Schools: The Impact of Conservative Christian Pressure Groups.

ERIC Educational Resources Information Center

Dorrell, Larry D.; Busch, Anne

2000-01-01

Presents an historical overview of the rise of conservative pressure groups after 1980 and their association with an increase in censorship activities in schools. Discusses the influence of the Reagan administration; library materials selection; textbook selection; secular humanism; and trying to affect the curriculum rather than targeting…

The Rapid Formation of Localized Compaction Bands Under Hydrostatic Load Leading to Pore-pressure Transients in Compacting Rocks

NASA Astrophysics Data System (ADS)

Faulkner, D.; Leclere, H.; Bedford, J. D.; Behnsen, J.; Wheeler, J.

2017-12-01

Compaction of porous rocks can occur uniformly or within localized deformation bands. The formation of compaction bands and their effects on deformation behaviour are poorly understood. Porosity may be primary and compaction can occur with burial, or it can be produced by metamorphic reactions with a solid volume reduction, that can then undergo collapse. We report results from hydrostatic compaction experiments on porous bassanite (CaSO4.0.5H2O) aggregates. Gypsum (CaSO4.2H2O) is first dehydrated under low effective pressure, 4 MPa, to produce a bassanite aggregate with a porosity of 27%. Compaction is induced by increasing confining pressure at rates from 0.001 MPa/s to 0.02 MPa/s while the sample is maintained at a temperature of 115°C. At slow compaction rates, porosity collapse proceeds smoothly. At higher compaction rates, sudden increases in the pore-fluid pressure occur with a magnitude of 5 MPa. Microstructural investigations using X-ray microtomography and SEM observations show that randomly oriented localized compaction features occur in all samples, where the bulk porosity of 18% outside the band is reduced to 5% inside the band. Previous work on deformation bands has suggested that localized compactive features only form under an elevated differential stress and not under a hydrostatic stress state. The magnitude of the pore-pressure pulses can be explained by the formation of compaction bands. The results indicate that the compaction bands can form by rapid (unstable) propagation across the sample above a critical strain rate, or quasi-statically at low compaction rates without pore-fluid pressure bursts. The absence of pore-fluid pressure bursts at slow compaction rates can be explained by viscous deformation of the bassanite aggregate around the tip of a propagating compaction band, relaxing stress, and promoting stable propagation. Conversely, at higher compaction rates, viscous deformation cannot relax the stress sufficiently and unstable, brittle propagation occurs. In nature, this type of compaction behaviour might result in a mechanism to produce pulses of pore pressure within porous rocks which might have a significant effect on the deformation behaviour at depth.

Local pH domains regulate NHE3-mediated Na+ reabsorption in the renal proximal tubule

PubMed Central

Burford, James L.; McDonough, Alicia A.; Holstein-Rathlou, Niels-Henrik; Peti-Peterdi, Janos

2014-01-01

The proximal tubule Na+/H+ exchanger 3 (NHE3), located in the apical dense microvilli (brush border), plays a major role in the reabsorption of NaCl and water in the renal proximal tubule. In response to a rise in blood pressure NHE3 redistributes in the plane of the plasma membrane to the base of the brush border, where NHE3 activity is reduced. This NHE3 redistribution is assumed to provoke pressure natriuresis; however, it is unclear how NHE3 redistribution per se reduces NHE3 activity. To investigate if the distribution of NHE3 in the brush border can change the reabsorption rate, we constructed a spatiotemporal mathematical model of NHE3-mediated Na+ reabsorption across a proximal tubule cell and compared the model results with in vivo experiments in rats. The model predicts that when NHE3 is localized exclusively at the base of the brush border, it creates local pH microdomains that reduce NHE3 activity by >30%. We tested the model's prediction experimentally: the rat kidney cortex was loaded with the pH-sensitive fluorescent dye BCECF, and cells of the proximal tubule were imaged in vivo using confocal fluorescence microscopy before and after an increase of blood pressure by ∼50 mmHg. The experimental results supported the model by demonstrating that a rise of blood pressure induces the development of pH microdomains near the bottom of the brush border. These local changes in pH reduce NHE3 activity, which may explain the pressure natriuresis response to NHE3 redistribution. PMID:25298526

Pressure dependence of coherence-incoherence crossover behavior in KFe2As2 observed by resistivity and 75As-NMR/NQR

NASA Astrophysics Data System (ADS)

Wiecki, P.; Taufour, V.; Chung, D. Y.; Kanatzidis, M. G.; Bud'ko, S. L.; Canfield, P. C.; Furukawa, Y.

2018-02-01

We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KFe2As2 under pressure (p ). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T*). T* is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3 d orbital-derived bands with the itinerant electron bands. No anomaly in T* is seen at the critical pressure pc=1.8 GPa where a change of slope of the superconducting (SC) transition temperature Tc(p ) has been observed. In contrast, Tc(p ) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1 /T1 data, although such a correlation cannot be seen in the replacement effects of A in the A Fe2As2 (A =K , Rb, Cs) family. In the superconducting state, two T1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T1 s indicates a nearly gapless state below Tc. On the other hand, the temperature dependence of the long component 1 /T1 L implies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe2As2 under pressure.

Postural changes may influence popliteal atherosclerosis by modifying local circumferential wall tension.

PubMed

Gemignani, Tiago; Matos-Souza, José R; Coelho, Otávio R; Franchini, Kleber G; Nadruz, Wilson

2008-11-01

Atherosclerosis of peripheral arteries typically affects vessels of the lower limbs, suggesting that local hemodynamic stimuli play a role in this process. Our study evaluated the effects of body postural changes on carotid and popliteal blood pressure, circumferential wall tension (CWT) and arterial strain, and investigated the relationship between such hemodynamic parameters and intima-media thickness (IMT) of these arteries. One hundred seventeen nondiabetic, nonhypertensive, nonsmoker subjects (48 men and 69 women) were enrolled and had their blood pressure measured in the arm and calf in supine and orthostatic positions. Echo-doppler analysis evaluated the common carotid and popliteal arteries after blood pressure measurements, while CWT was calculated according to Laplace's law. The results showed that changing from supine to orthostatic posture increased blood pressure and CWT in popliteal but not in carotid arteries. Partial correlation analysis adjusted for age and body mass index revealed no major relationship between IMT of the studied vessels and local blood pressure or arterial strain. Conversely, supine and orthostatic CWT exhibited comparable correlation coefficients with carotid IMT, while orthostatic CWT displayed a stronger relationship with popliteal IMT than with supine CWT. These results were confirmed by multiple linear regression analysis that included age, sex, body mass index, lipid fractions and glucose as independent variables. Overall, our results indicate that orthostatic CWT is a stronger hemodynamic predictor of popliteal IMT than supine CWT, suggesting that erectile posture may be a potential risk factor for popliteal atherosclerosis because it increases the local hemodynamic burden. (Hypertens Res 2008; 31: 2059-2064).

The effective forces transmitted by high-speed, low-amplitude thoracic manipulation.

PubMed

Herzog, W; Kats, M; Symons, B

2001-10-01

Twenty asymptomatic volunteers each received three spinal manipulative treatments to the thoracic spine. The treatments consisted of a straight posterior-to-anterior high-speed, low-amplitude thrust to the transverse process of T3-T10 using a reinforced hypothenar contact. All treatments were given by a full-time practicing clinician with 3 years of experience. The primary objective of this study was to quantify local measures of loading applied by the clinician on the volunteers during spinal manipulative treatments and to compare these local measures of loading with previously described global measures. The sparse information on the mechanics of spinal manipulative treatments deals exclusively with global force or pressure measurements. On the basis of these global data, incorrect conclusions may be drawn about the beneficial effects of spinal manipulative therapy, the loading of internal structures, and the risks associated with these treatments. Twenty asymptomatic subjects each received three posterior-to-anterior, high-speed, low-amplitude spinal manipulative treatments to the transverse process of the thoracic spine. Total force, local force, contact area, peak pressure, and average pressure at the contact interface between clinician and subject were measured continuously by use of a thin, flexible pressure pad. Local and global measures of loading were compared and analyzed by use of nonparametric statistics (alpha = 0.01). The average peak total force was 238.2 N. The average peak local force over a target area of 25 mm2 was 5 N, indicating that global measures of loading vastly overestimate the local effective forces at the target site. The peak pressure point moved, on average, 9.8 mm during the course of the manipulation. To the authors' best knowledge, this is the first study to quantify local, effective measures of loading and compare them with the global measures typically used. The conclusions are limited because the study used a single clinician. The effective loading of specific target sites is much smaller than the global measures might suggest. This result occurs because as the forces during spinal manipulative treatment increase, so does the contact area; therefore, much of the total treatment force is taken up by non-target-specific tissues. Because of the vast discrepancy between the global and local measures of loading, it is suggested that risk-benefit assessments of high-speed, low-amplitude spinal manipulative treatments should be made, including local measures of loading. Finally, because theoretical approaches and the inverse dynamics approach can provide only global measures of loading, the results of such studies should be interpreted with caution.

Uniting sex and eukaryote origins in an emerging oxygenic world.

PubMed

Gross, Jeferson; Bhattacharya, Debashish

2010-08-23

Theories about eukaryote origins (eukaryogenesis) need to provide unified explanations for the emergence of diverse complex features that define this lineage. Models that propose a prokaryote-to-eukaryote transition are gridlocked between the opposing "phagocytosis first" and "mitochondria as seed" paradigms, neither of which fully explain the origins of eukaryote cell complexity. Sex (outcrossing with meiosis) is an example of an elaborate trait not yet satisfactorily addressed in theories about eukaryogenesis. The ancestral nature of meiosis and its dependence on eukaryote cell biology suggest that the emergence of sex and eukaryogenesis were simultaneous and synergic and may be explained by a common selective pressure. We propose that a local rise in oxygen levels, due to cyanobacterial photosynthesis in ancient Archean microenvironments, was highly toxic to the surrounding biota. This selective pressure drove the transformation of an archaeal (archaebacterial) lineage into the first eukaryotes. Key is that oxygen might have acted in synergy with environmental stresses such as ultraviolet (UV) radiation and/or desiccation that resulted in the accumulation of reactive oxygen species (ROS). The emergence of eukaryote features such as the endomembrane system and acquisition of the mitochondrion are posited as strategies to cope with a metabolic crisis in the cell plasma membrane and the accumulation of ROS, respectively. Selective pressure for efficient repair of ROS/UV-damaged DNA drove the evolution of sex, which required cell-cell fusions, cytoskeleton-mediated chromosome movement, and emergence of the nuclear envelope. Our model implies that evolution of sex and eukaryogenesis were inseparable processes. Several types of data can be used to test our hypothesis. These include paleontological predictions, simulation of ancient oxygenic microenvironments, and cell biological experiments with Archaea exposed to ROS and UV stresses. Studies of archaeal conjugation, prokaryotic DNA recombination, and the universality of nuclear-mediated meiotic activities might corroborate the hypothesis that sex and the nucleus evolved to support DNA repair. Oxygen tolerance emerges as an important principle to investigate eukaryogenesis. The evolution of eukaryotic complexity might be best understood as a synergic process between key evolutionary innovations, of which meiosis (sex) played a central role. This manuscript was reviewed by Eugene V. Koonin, Anthony M. Poole, and Gáspár Jékely.

Global versus local linear beat-to-beat analysis of the relationship between arterial pressure and pulse transit time during dynamic exercise.

PubMed

Porta, A; Gasperi, C; Nollo, G; Lucini, D; Pizzinelli, P; Antolini, R; Pagani, M

2006-04-01

Global linear analysis has been traditionally performed to verify the relationship between pulse transit time (PTT) and systolic arterial pressure (SAP) at the level of their spontaneous beat-to-beat variabilities: PTT and SAP have been plotted in the plane (PTT,SAP) and a significant linear correlation has been found. However, this relationship is weak and in specific individuals cannot be found. This result prevents the utilization of the SAP-PTT relationship to derive arterial pressure changes from PTT measures on an individual basis. We propose a local linear approach to study the SAP-PTT relationship. This approach is based on the definition of short SAP-PTT sequences characterized by SAP increase (decrease) and PTT decrease (increase) and on their search in the SAP and PTT beat-to-beat series. This local approach was applied to PTT and SAP series derived from 13 healthy humans during incremental supine dynamic exercise (at 10, 20 and 30% of the nominal individual maximum effort) and compared to the global approach. While global approach failed in some subjects, local analysis allowed the extraction of the gain of the SAP-PTT relationship in all subjects both at rest and during exercise. When both local and global analyses were successful, the local SAP-PTT gain is more negative than the global one as a likely result of noise reduction.

Resistance properties of coal-water slurry flowing through local piping fittings

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

Liu, Meng; Duan, Yu Feng

2009-07-15

Local resistance characteristics of coal-water slurry (CWS) flowing through three types of piping components, namely gradual contractions, sudden contractions and 90 horizontal bends, were investigated at a transportation test facility. The results show that CWS exhibits different rheological behaviors, i.e., the shear-thinning, Newtonian, and shear-thicken, at different shear rates. When CWS flows through the gradual contractions, the local pressure loss firstly decreases to a minimum, and then increases as the gradual contraction angle ({theta}) increases. When the CWS flow through the sudden contractions, with the increase of pipe diameter ratio ({beta}), the local pressure loss increases for the two kindsmore » of CWS, SHEN-HUA (S-H) CWS and YAN-ZHOU (Y-Z) CWS whose mass concentration range from 57% to 59% and 59% to 62%, respectively. For 90 horizontal bends, there is an optimal value of the bend diameter ratio (Rc/D) at which the local pressure loss is the least. Furthermore, the local resistance coefficient (K) in the empirical correlations is determined from the experimental data. The correlations show that as Re increases, K of the three fittings declines quickly at first. However, with further increase in Re, K shows different behaviors for the three fittings due to the special rheological property of CWS at higher shear rates. The factors of {theta}, {beta} and Rc/D have minor effects on K. (author)« less

Resistance properties of coal-water slurry flowing through local piping fittings

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

Meng, L.; Duan, Y.F.

2009-07-15

Local resistance characteristics of coal-water slurry (CWS) flowing through three types of piping components, namely gradual contractions, sudden contractions and 90 horizontal bends, were investigated at a transportation test facility. The results show that CWS exhibits different rheological behaviors, i.e., the shear-thinning, Newtonian, and shear-thicken, at different shear rates. When CWS flows through the gradual contractions, the local pressure loss firstly decreases to a minimum, and then increases as the gradual contraction angle {theta} increases. When the CWS flow through the sudden contractions, with the increase of pipe diameter ratio {beta}, the local pressure loss increases for the two kindsmore » of CWS, SHEN-HUA (S-H) CWS and YAN-ZHOU (Y-Z) CWS whose mass concentration range from 57% to 59% and 59% to 62%, respectively. For 90 horizontal bends, there is an optimal value of the bend diameter ratio (Rc/D) at which the local pressure loss is the least. Furthermore, the local resistance coefficient (K) in the empirical correlations is determined from the experimental data. The correlations show that as Re increases, K of the three fittings declines quickly at first. However, with further increase in Re, K shows different behaviors for the three fittings due to the special rheological property of CWS at higher shear rates. The factors of theta, beta and Rc/D have minor effects on K.« less

Determination and Use of the Local Recovery Factor for Calculating the Effectiveness Gas Temperature for Turbine Blades / Jack B. Esgar and Alfred L. Lea

NASA Technical Reports Server (NTRS)

Esgar, Jack B; Lea, Alfred L

1951-01-01

In an in experimental investigation of local recovery factors for a blade having a pressure distribution similar to that of a typical reaction-type turbine blade, it a was found that the recovery factors were essentially independent of Mach number, Reynolds number, pressure gradient, and position on the blade surface except for regions where the boundary layer was probably in the transition range from laminar to turbulent. The recommended value of local subsonic recovery factor for use in calculating the effective gas temperature for gas turbine blades was 0.89.

The incidence of pressure ulcer in patients on mechanical ventilation andeffects of selected risk factors on pressure ulcer development.

PubMed

Karayurt, Özgül; Akyol, Özay; Kılıçaslan, Necmiye; Akgün, Nuray; Sargın, Ümran; Kondakçı, Melike; Ekinci, Hanım; Sarı, Neslihan

2016-11-17

This study aimed to determine the incidence of pressure ulcers in patients on mechanical ventilation and selected risk factors likely to play a role in pressure ulcer development. The study included 110 patients recruited from an anesthesia critical care unit of a university hospital. Data were collected with a demographic and clinical characteristics form. The form was composed of questions about demographic characteristics and clinical features including diagnosis, duration of mechanical ventilation, general well-being, oxygenation, perfusion, and skin condition. The incidence of pressure ulcer was 15.5%. Duration of mechanical ventilation was longer and the body mass index was higher in patients developing pressure ulcers than in those without pressure ulcers. Additionally, 90.11% of patients with pressure ulcers had edema and 82.35% of patients with pressure ulcers received vasopressin. The patients with pressure ulcers had higher PH levels, lower PaO2 levels, higher PCO2 levels, lower SaO2 levels, and higher urine output. It can be recommended that nurses and other health professionals should be aware of factors playing a role in pressure ulcer development and should be able to conduct appropriate interventions to prevent pressure ulcers.

On the maintenance of genetic variation and adaptation to environmental change: considerations from population genomics in fishes.

PubMed

Bernatchez, L

2016-12-01

The first goal of this paper was to overview modern approaches to local adaptation, with a focus on the use of population genomics data to detect signals of natural selection in fishes. Several mechanisms are discussed that may enhance the maintenance of genetic variation and evolutionary potential, which have been overlooked and should be considered in future theoretical development and predictive models: the prevalence of soft sweeps, polygenic basis of adaptation, balancing selection and transient polymorphisms, parallel evolution, as well as epigenetic variation. Research on fish population genomics has provided ample evidence for local adaptation at the genome level. Pervasive adaptive evolution, however, seems to almost never involve the fixation of beneficial alleles. Instead, adaptation apparently proceeds most commonly by soft sweeps entailing shifts in frequencies of alleles being shared between differentially adapted populations. One obvious factor contributing to the maintenance of standing genetic variation in the face of selective pressures is that adaptive phenotypic traits are most often highly polygenic, and consequently the response to selection should derive mostly from allelic co-variances among causative loci rather than pronounced allele frequency changes. Balancing selection in its various forms may also play an important role in maintaining adaptive genetic variation and the evolutionary potential of species to cope with environmental change. A large body of literature on fishes also shows that repeated evolution of adaptive phenotypes is a ubiquitous evolutionary phenomenon that seems to occur most often via different genetic solutions, further adding to the potential options of species to cope with a changing environment. Moreover, a paradox is emerging from recent fish studies whereby populations of highly reduced effective population sizes and impoverished genetic diversity can apparently retain their adaptive potential in some circumstances. Although more empirical support is needed, several recent studies suggest that epigenetic variation could account for this apparent paradox. Therefore, epigenetic variation should be fully integrated with considerations pertaining to role of soft sweeps, polygenic and balancing selection, as well as repeated adaptation involving different genetic basis towards improving models predicting the evolutionary potential of species to cope with a changing world. © 2016 The Fisheries Society of the British Isles.

Localization and superconductivity in (BEDT-TIF) 2Cu[N(CN) 2]Cl: Pressure effect

NASA Astrophysics Data System (ADS)

Sushko, Yu. V.; Bondarenko, V. A.; Petrosov, R. A.; Kushch, N. D.; Yagubskii, E. B.

1991-12-01

At ambient pressure titled salt exhibits the insulating ground state. Superconductivity with T c near 12 K appears at the pressure of 95 bar and under the moderate pressures coexists with the high-temperature semiconducting regime. At 340 bar the metallic behavior of resistance is stabilized in whole temperature range and T c reaches the maximum value (midpoint 12.8 K, onset 13.8 K). Further pressure increasing causes rapid T c decreasing.

An automated pressure data acquisition system for evaluation of pressure sensitive paint chemistries

NASA Technical Reports Server (NTRS)

Sealey, Bradley S.; Mitchell, Michael; Burkett, Cecil G.; Oglesby, Donald M.

1993-01-01

An automated pressure data acquisition system for testing of pressure sensitive phosphorescent paints was designed, assembled, and tested. The purpose of the calibration system is the evaluation and selection of pressure sensitive paint chemistries that could be used to obtain global aerodynamic pressure distribution measurements. The test apparatus and setup used for pressure sensitive paint characterizations is described. The pressure calibrations, thermal sensitivity effects, and photodegradation properties are discussed.

Investigation of the Loads on a Conventional Front and Rear Sliding Canopy

NASA Technical Reports Server (NTRS)

Dexter, Howard E.; Rickey, Edward A.

1947-01-01

As one phase of a comprehensive canopy load investigation, conventional front and rear sliding canopies which are typified by installation on the SB2C-4E airplane, were tested in the Langley full-scale tunnel to determine the pressure distributions and the aerodynamic loads on the canopies. A preliminary analysis of the results of these tests is presented in this report. Plots are presented that show the distribution of pressure at four longitudinal stations through each canopy for a range of conditions selected to determine the effects of varying canopy position, yaw, lift coefficient, and power. The results indicate that the maximum loads, based on the external-internal pressure differential, for the front and rear canopies were obtained with the airplane simulating the high speed flight condition. The highest loading on the front canopy was in the exploding direction for the configuration with the front and rear canopies closed. The highest loads on the rear canopy were in the crushing direction with the front canopy open and the rear canopy closed. For most of the simulated flight conditions, the highest loads on the front canopy, per unit area, were over twice as great as the highest loads on the rear canopy when the comparison was made for the most critical canopy configuration in each case. The external pressure distribution over the front and rear canopies, which were fairly symmetrical to 0 degree angle of yaw, were greatly distorted at other yaw attitudes, particularly for the propeller operating conditions. These distorted pressure distributions resulted in local exploding and crushing loads on both canopies which were often considerably higher than the average canopy loads.

Volatile Emissions from Compressed Tissue

PubMed Central

Dini, Francesca; Capuano, Rosamaria; Strand, Tillan; Ek, Anna-Christina; Lindgren, Margareta; Paolesse, Roberto; Di Natale, Corrado; Lundström, Ingemar

2013-01-01

Since almost every fifth patient treated in hospital care develops pressure ulcers, early identification of risk is important. A non-invasive method for the elucidation of endogenous biomarkers related to pressure ulcers could be an excellent tool for this purpose. We therefore found it of interest to determine if there is a difference in the emissions of volatiles from compressed and uncompressed tissue. The ultimate goal is to find a non-invasive method to obtain an early warning for the risk of developing pressure ulcers for bed-ridden persons. Chemical analysis of the emissions, collected in compresses, was made with gas-chromatography – mass spectrometry and with a chemical sensor array, the so called electronic nose. It was found that the emissions from healthy and hospitalized persons differed significantly irrespective of the site. Within each group there was a clear difference between the compressed and uncompressed site. Peaks that could be certainly deemed as markers of the compression were, however, not identified. Nonetheless, different compounds connected to the application of local mechanical pressure were found. The results obtained with GC-MS reveal the complexity of VOC composition, thus an array of non-selective chemical sensors seems to be a suitable choice for the analysis of skin emission from compressed tissues; it may represent a practical instrument for bed side diagnostics. Results show that the adopted electronic noses are likely sensitive to the total amount of the emission rather than to its composition. The development of a gas sensor-based device requires then the design of sensor receptors adequate to detect the VOCs bouquet typical of pressure. This preliminary experiment evidences the necessity of studies where each given person is followed for a long time in a ward in order to detect the insurgence of specific VOCs pattern changes signalling the occurrence of ulcers. PMID:23874929

Blood Pressure Control in Aging Predicts Cerebral Atrophy Related to Small-Vessel White Matter Lesions.

PubMed

Kern, Kyle C; Wright, Clinton B; Bergfield, Kaitlin L; Fitzhugh, Megan C; Chen, Kewei; Moeller, James R; Nabizadeh, Nooshin; Elkind, Mitchell S V; Sacco, Ralph L; Stern, Yaakov; DeCarli, Charles S; Alexander, Gene E

2017-01-01

Cerebral small-vessel damage manifests as white matter hyperintensities and cerebral atrophy on brain MRI and is associated with aging, cognitive decline and dementia. We sought to examine the interrelationship of these imaging biomarkers and the influence of hypertension in older individuals. We used a multivariate spatial covariance neuroimaging technique to localize the effects of white matter lesion load on regional gray matter volume and assessed the role of blood pressure control, age and education on this relationship. Using a case-control design matching for age, gender, and educational attainment we selected 64 participants with normal blood pressure, controlled hypertension or uncontrolled hypertension from the Northern Manhattan Study cohort. We applied gray matter voxel-based morphometry with the scaled subprofile model to (1) identify regional covariance patterns of gray matter volume differences associated with white matter lesion load, (2) compare this relationship across blood pressure groups, and (3) relate it to cognitive performance. In this group of participants aged 60-86 years, we identified a pattern of reduced gray matter volume associated with white matter lesion load in bilateral temporal-parietal regions with relative preservation of volume in the basal forebrain, thalami and cingulate cortex. This pattern was expressed most in the uncontrolled hypertension group and least in the normotensives, but was also more evident in older and more educated individuals. Expression of this pattern was associated with worse performance in executive function and memory. In summary, white matter lesions from small-vessel disease are associated with a regional pattern of gray matter atrophy that is mitigated by blood pressure control, exacerbated by aging, and associated with cognitive performance.

Flight Test Results from the Rake Airflow Gage Experiment on the F-15B

NASA Technical Reports Server (NTRS)

Frederick, Michael; Ratnayake, Nalin

2011-01-01

The results are described of the Rake Airflow Gage Experiment (RAGE), which was designed and fabricated to support the flight test of a new supersonic inlet design using Dryden's Propulsion Flight Test Fixture (PFTF) and F-15B testbed airplane (see figure). The PFTF is a unique pylon that was developed for flight-testing propulsion-related experiments such as inlets, nozzles, and combustors over a range of subsonic and supersonic flight conditions. The objective of the RAGE program was to quantify the local flowfield at the aerodynamic interface plane of the Channeled Centerbody Inlet Experiment (CCIE). The CCIE is a fixed representation of a conceptual mixed-compression supersonic inlet with a translating biconic centerbody. The primary goal of RAGE was to identify the relationship between free-stream and local Mach number in the low supersonic regime, with emphasis on the identification of the particular free-stream Mach number that produced a local Mach number of 1.5. Measurements of the local flow angularity, total pressure distortion, and dynamic pressure over the interface plane were also desired. The experimental data for the RAGE program were obtained during two separate research flights. During both flights, local flowfield data were obtained during straight and level acceleration segments out to steady-state test points. The data obtained from the two flights showed small variations in Mach number, flow angularity, and dynamic pressure across the interface plane at all flight conditions. The data show that a free-stream Mach number of 1.65 will produce the desired local Mach number of 1.5 for CCIE. The local total pressure distortion over the interface plane at this condition was approximately 1.5%. At this condition, there was an average of nearly 2 of downwash over the interface plane. This small amount of downwash is not expected to adversely affect the performance of the CCIE inlet.

Noradrenaline activates the NO/cGMP/ATP-sensitive K(+) channels pathway to induce peripheral antinociception in rats.

PubMed

Romero, Thiago R L; Guzzo, Luciana S; Perez, Andrea C; Klein, André; Duarte, Igor D G

2012-03-31

Despite the classical peripheral pronociceptive effect of noradrenaline (NA), recently studies showed the involvement of NA in antinociceptive effect under immune system interaction. In addition, the participation of the NO/cGMP/KATP pathway in the peripheral antinociception has been established by our group as the molecular mechanism of another adrenoceptor agonist xylazine. Thus the aim of this study was to obtain pharmacological evidences for the involvement of the NO/cGMP/KATP pathway in the peripheral antinociceptive effect induced by exogenous noradrenaline. The rat paw pressure test was used, with hyperalgesia induced by intraplantar injection of prostaglandin E(2) (2μg/paw). All drugs were locally administered into the right hind paw of male Wistar rats. NA (5, 20 and 80ng/paw) elicited a local inhibition of hyperalgesia. The non-selective NO synthase inhibitor l-NOarg (12, 18 and 24μg/paw) antagonized the antinociception effect induced by the highest dose of NA. The soluble guanylyl cyclase inhibitor ODQ (25, 50 and 100μg/paw) antagonized the NA-induced effect; and cGMP-phosphodiesterase inhibitor zaprinast (50μg/paw) potentiated the antinociceptive effect of NA low dose (5ng/paw). In addition, the local effect of NA was antagonized by a selective blocker of an ATP-sensitive K(+) channel, glibenclamide (20, 40 and 80μg/paw). On the other hand, the specifically voltage-dependent K(+) channel blocker, tetraethylammonium (30μg/paw), Ca(2+)-activated K(+) channel blockers of small and large conductance types dequalinium (50μg/paw) and paxilline (20μg/paw), respectively, were not able to block local antinociceptive effect of NA. The results provide evidences that NA probably induces peripheral antinociceptive effects by activation of the NO/cGMP/KATP pathway. Copyright © 2012 Elsevier Inc. All rights reserved.

What Physical Fitness Component Is Most Closely Associated With Adolescents' Blood Pressure?

PubMed

Nunes, Heloyse E G; Alves, Carlos A S; Gonçalves, Eliane C A; Silva, Diego A S

2017-12-01

This study aimed to determine which of four selected physical fitness variables, would be most associated with blood pressure changes (systolic and diastolic) in a large sample of adolescents. This was a descriptive and cross-sectional, epidemiological study of 1,117 adolescents aged 14-19 years from southern Brazil. Systolic and diastolic blood pressure were measured by a digital pressure device, and the selected physical fitness variables were body composition (body mass index), flexibility (sit-and-reach test), muscle strength/resistance (manual dynamometer), and aerobic fitness (Modified Canadian Aerobic Fitness Test). Simple and multiple linear regression analyses revealed that aerobic fitness and muscle strength/resistance best explained variations in systolic blood pressure for boys (17.3% and 7.4% of variance) and girls (7.4% of variance). Aerobic fitness, body composition, and muscle strength/resistance are all important indicators of blood pressure control, but aerobic fitness was a stronger predictor of systolic blood pressure in boys and of diastolic blood pressure in both sexes.

Negative Pressure Wound Therapy Reduces the Effectiveness of Traditional Local Antibiotic Depot in a Large Complex Musculoskeletal Wound Animal Model

DTIC Science & Technology

2012-09-01

in particular, local antibiotic delivery via polymethylmethacrylate (PMMA) bone cement and negative pressure wound therapy (NPWT). In cases with gross...release of gentamicin from polymethylmethacrylate beads. An experimental and pharmacoki- netic study. J Bone Joint Surg Br. 1978;60-B:270 275. 7...diffusion from antibiotic-impregnated polymethylmethacrylate beads. Clin Orthop Relat Res. 1992;278:244 252. Stinner et al J Orthop Trauma Volume

A randomized controlled clinical trial to evaluate blood pressure changes in patients undergoing extraction under local anesthesia with vasopressor use.

PubMed

Uzeda, Marcelo José; Moura, Brenda; Louro, Rafael Seabra; da Silva, Licínio Esmeraldo; Calasans-Maia, Mônica Diuana

2014-05-01

The control of hypertensive patients' blood pressure and heart rate using vasoconstrictors during surgical procedures under anesthesia is still a major concern in everyday surgical practice. This clinical trial aimed to evaluate the variation of blood pressure and heart rate in nonhypertensive and controlled hypertensive voluntary subjects undergoing oral surgery under local anesthesia with lidocaine hydrochloride and epinephrine at 1:100,000 (Alphacaine; DFL, Brazil), performed in the Oral Surgery Department, Dentistry School, Fluminense Federal University. In total, 25 voluntary subjects were divided into 2 groups: nonhypertensive (n = 15) and controlled hypertensives (n = 10). Blood pressure and heart rate were measured at 4 different times: T0, in the waiting room; T1, after placement of the surgical drapes; T2, 10 minutes after anesthesia injection; and T3, at the end of the surgical procedure. A statistically significant difference (P < 0.05) between the groups was found at times T0 and T2 for the systolic pressure but only at time T0 for the diastolic pressure. The assessment of the heart rate of both groups showed a statistically significant difference (P < 0.05) at time T1. An analysis of the employed anesthetic volume indicated no statistically significant difference (P > 0.05) between the amount administered to nonhypertensive and hypertensive subjects. It was concluded that the local anesthetics studied could safely be used in controlled hypertensive and nonhypertensive patients in compliance with the maximum recommended doses.

Influence of condensation on heat flux and pressure measurements in a detonation-based short-duration facility

NASA Astrophysics Data System (ADS)

Haase, S.; Olivier, H.

2017-10-01

Detonation-based short-duration facilities provide hot gas with very high stagnation pressures and temperatures. Due to the short testing time, complex and expensive cooling techniques of the facility walls are not needed. Therefore, they are attractive for economical experimental investigations of high-enthalpy flows such as the flow in a rocket engine. However, cold walls can provoke condensation of the hot combustion gas at the walls. This has already been observed in detonation tubes close behind the detonation wave, resulting in a loss of tube performance. A potential influence of condensation at the wall on the experimental results, like wall heat fluxes and static pressures, has not been considered so far. Therefore, in this study the occurrence of condensation and its influence on local heat flux and pressure measurements has been investigated in the nozzle test section of a short-duration rocket-engine simulation facility. This facility provides hot water vapor with stagnation pressures up to 150 bar and stagnation temperatures up to 3800 K. A simple method has been developed to detect liquid water at the wall without direct optical access to the flow. It is shown experimentally and theoretically that condensation has a remarkable influence on local measurement values. The experimental results indicate that for the elimination of these influences the nozzle wall has to be heated to a certain temperature level, which exclusively depends on the local static pressure.

Elevated compartment pressures from copperhead envenomation successfully treated with antivenin.

PubMed

Mazer-Amirshahi, Maryann; Boutsikaris, Amy; Clancy, Cathleen

2014-01-01

Copperhead envenomation causes local soft tissue effects; however, associated compartment syndrome is rare. We report a case of a 17-month-old with significantly elevated compartment pressures successfully treated with antivenin and supportive care. A 17-month-old girl sustained a copperhead bite to the foot and presented with circumferential edema, erythema, and ecchymosis of the foot and distal ankle. The patient had palpable pulses and was neurologically intact. Four vials of Crotalidae polyvalent immune Fab was initiated and additional doses were administered in an attempt to achieve local control. Within 10 h of presentation, the patient's edema extended to the groin, although sensation was maintained and pulses were documented by Doppler. Lower-extremity compartment pressures were measured and were most notable for an anterior pressure of 85 mm Hg, despite having received 12 vials of antivenin. Fasciotomy was deferred and the patient received two additional six-vial doses of antivenin to achieve local control. Compartment pressures improved with a 2.2-cm mean decrease in limb diameter within 48 h. Maintenance dosing was initiated and the patient ultimately received a total of 26 vials of antivenin. The patient did not develop significant coagulopathy or thrombocytopenia. Swelling continued to improve with return of limb function. In this case, early and aggressive treatment with antivenin may have avoided invasive fasciotomy, and its use should be considered in patients with copperhead envenomation and significantly elevated compartment pressures. Copyright © 2014 Elsevier Inc. All rights reserved.

Nondestructive equipment study

NASA Technical Reports Server (NTRS)

1985-01-01

Identification of existing nondestructive Evaluation (NDE) methods that could be used in a low Earth orbit environment; evaluation of each method with respect to the set of criteria called out in the statement of work; selection of the most promising NDE methods for further evaluation; use of selected NDE methods to test samples of pressure vessel materials in a vacuum; pressure testing of a complex monolythic pressure vessel with known flaws using acoustic emissions in a vacuum; and recommendations for further studies based on analysis and testing are covered.

32 CFR 1602.14 - Local board.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 32 National Defense 6 2011-07-01 2011-07-01 false Local board. 1602.14 Section 1602.14 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.14 Local board. A local board or a panel thereof of the Selective Service System is a group of not less...

32 CFR 1602.14 - Local board.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 32 National Defense 6 2010-07-01 2010-07-01 false Local board. 1602.14 Section 1602.14 National Defense Other Regulations Relating to National Defense SELECTIVE SERVICE SYSTEM DEFINITIONS § 1602.14 Local board. A local board or a panel thereof of the Selective Service System is a group of not less...

Rhinoceros beetles suffer male-biased predation by mammalian and avian predators.

PubMed

Kojima, Wataru; Sugiura, Shinji; Makihara, Hiroshi; Ishikawa, Yukio; Takanashi, Takuma

2014-03-01

Male sexually-selected traits often impose an increased risk of predation on their bearers, causing male-biased predation. We investigated whether males of the sap-feeding Japanese rhinoceros beetle Trypoxylus dichotomus were more susceptible to predation than females by comparing the morphology of beetles caught in bait traps with the remains of beetles found on the ground. The males of this species are larger than the females and have a horn on the head. We found that predation pressure was greater for males than for females, and that larger individuals of both sexes were more vulnerable to predation. We identified two predators, the raccoon dog Nyctereutes procyonoides and jungle crow Corvus macrorhynchos, by monitoring sap-site trees with infrared video cameras. Raccoon dogs visited sap-site trees at night, while crows came after daybreak. The highest frequency of visits by both predators was observed in the first half of August, which matches the peak season of T. dichotomus. Raccoon dogs often left bite marks on the remains of prey, whereas crows did not. Bite marks were found on most of the remains collected at two distant localities, which suggested that predation by raccoon dogs is common. Size- and sex-dependent differences in the conspicuousness and active period of T. dichotomus probably explain these biased predation patterns. Our results suggest that having a large horn/body is costly in terms of the increased risk of predation. Predation cost may act as a stabilizing selection pressure against the further exaggeration of male sexual traits.

Similar Pressures, Different Contexts: Public Attitudes toward Government Intervention for Health Care in 21 Nations

ERIC Educational Resources Information Center

Kikuzawa, Saeko; Olafsdottir, Sigrun; Pescosolido, Bernice A.

2008-01-01

Health care systems worldwide are experiencing similar pressures such as rising cost, aging populations, and increased burden of disease. While policy makers in all countries face these challenges, their responses must consider local pressures, particularly the implicit social contract between the state, medicine, and insurers. We argue that…

Induced charge electroosmosis micropumps using arrays of Janus micropillars.

PubMed

Paustian, Joel S; Pascall, Andrew J; Wilson, Neil M; Squires, Todd M

2014-09-07

We report on a microfluidic AC-driven electrokinetic pump that uses Induced Charge Electro-Osmosis (ICEO) to generate on-chip pressures. ICEO flows occur when a bulk electric field polarizes a metal object to induce double layer formation, then drives electroosmotic flow. A microfabricated array of metal-dielectric Janus micropillars breaks the symmetry of ICEO flow, so that an AC electric field applied across the array drives ICEO flow along the length of the pump. When pumping against an external load, a pressure gradient forms along the pump length. The design was analyzed theoretically with the reciprocal theorem. The analysis reveals a maximum pressure and flow rate that depend on the ICEO slip velocity and micropillar geometry. We then fabricate and test the pump, validating our design concept by demonstrating non-local pressure driven flow using local ICEO slip flows. We varied the voltage, frequency, and electrolyte composition, measuring pump pressures of 15-150 Pa. We use the pump to drive flows through a high-resistance microfluidic channel. We conclude by discussing optimization routes suggested by our theoretical analysis to enhance the pump pressure.

Activation of transient receptor potential vanilloid-1 (TRPV1) influences how retinal ganglion cell neurons respond to pressure-related stress

PubMed Central

Sappington, Rebecca M; Sidorova, Tatiana; Ward, Nicholas J; Chakravarthy, Rohini; Ho, Karen W; Calkins, David J

2015-01-01

Our recent studies implicate the transient receptor potential vanilloid-1 (TRPV1) channel as a mediator of retinal ganglion cell (RGC) function and survival. With elevated pressure in the eye, TRPV1 increases in RGCs, supporting enhanced excitability, while Trpv1 -/- accelerates RGC degeneration in mice. Here we find TRPV1 localized in monkey and human RGCs, similar to rodents. Expression increases in RGCs exposed to acute changes in pressure. In retinal explants, contrary to our animal studies, both Trpv1 -/- and pharmacological antagonism of the channel prevented pressure-induced RGC apoptosis, as did chelation of extracellular Ca2+. Finally, while TRPV1 and TRPV4 co-localize in some RGC bodies and form a protein complex in the retina, expression of their mRNA is inversely related with increasing ocular pressure. We propose that TRPV1 activation by pressure-related insult in the eye initiates changes in expression that contribute to a Ca2+-dependent adaptive response to maintain excitatory signaling in RGCs. PMID:25713995

Phase diagram of pressure-induced superconductor β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) with localized magnetic moments

NASA Astrophysics Data System (ADS)

Choi, E. S.; Graf, D.; Tokumoto, T.; Brooks, J. S.; Yamada, Jun-Ichi

2007-03-01

We have investigated transport and magnetization properties of β-(BDA-TTP)2MX4 (M=Fe, Ga and X=Cl, Br) as a function of pressure, temperature and magnetic field. The title material undergoes metal-insulator transitions above 100 K at ambient pressure. The insulating phase is suppressed with pressure and superconductivity eventually appears above Pc= 4.5 kbar (X=Cl) and 13 kbar (X=Br). The general temperature-pressure (TP) phase diagram is similar each other, while higher pressure is required for X=Br compounds to suppress the insulating state and induce the superconductivity. Pressure dependent DC magnetization studies on β-(BDA-TTP)2FeCl4 compound revealed that the AFM ordering persist well above Pc. In spite of similarity of phase diagram between M=Fe and M=Ga compounds, magnetoresistance results show distinct behaviors, which indicates the magnetic interaction with the conduction electrons are still effective. The comparison between X=Cl and X=Br compounds suggests the anion-size effect rather than the existence of localized magnetic moments plays more important role in determining the ground state.

Development of a super-pressure balloon with a diamond-shaped net

NASA Astrophysics Data System (ADS)

Saito, Y.; Iijima, I.; Matsuzaka, Y.; Matsushima, K.; Tanaka, S.; Kajiwara, K.; Shimadu, S.

2014-10-01

The essential reason of the lobed-pumpkin shaped super-pressure balloon to withstand against the high pressure is that the local curvature of the balloon film is kept small. Recently, it has been found that the small local curvature can also be obtained if the balloon is covered by a diamond-shaped net with a vertically elongated shape. The development of the super-pressure balloon using this method was started from a 3-m balloon with a polyethylene film covered by a net using Kevlar ropes. The ground inflation test showed the expected high burst pressure. Then, a 6-m and a 12-m balloon using a polyethylene film and a net using the Vectran were developed and stable deployment was checked through the ground inflation tests. The flight test of a 3000 m3 balloon was performed in 2013 and shown to resist a pressure of at least 400 Pa. In the future, after testing a new design to relax a possible stress concentration around the polar area, test flights of scaled balloons will be performed gradually enlarging their size. The goal is to launch a 300,000 m3 super-pressure balloon.

Localization of incipient tip vortex cavitation using ray based matched field inversion method

NASA Astrophysics Data System (ADS)

Kim, Dongho; Seong, Woojae; Choo, Youngmin; Lee, Jeunghoon

2015-10-01

Cavitation of marine propeller is one of the main contributing factors of broadband radiated ship noise. In this research, an algorithm for the source localization of incipient vortex cavitation is suggested. Incipient cavitation is modeled as monopole type source and matched-field inversion method is applied to find the source position by comparing the spatial correlation between measured and replicated pressure fields at the receiver array. The accuracy of source localization is improved by broadband matched-field inversion technique that enhances correlation by incoherently averaging correlations of individual frequencies. Suggested localization algorithm is verified through known virtual source and model test conducted in Samsung ship model basin cavitation tunnel. It is found that suggested localization algorithm enables efficient localization of incipient tip vortex cavitation using a few pressure data measured on the outer hull above the propeller and practically applicable to the typically performed model scale experiment in a cavitation tunnel at the early design stage.

Breakdown of Amontons' Law of Friction in Sheared-Elastomer with Local Amontons' Friction

NASA Astrophysics Data System (ADS)

Matsukawa, Hiroshi; Otsuki, Michio

2012-02-01

It is well known that Amontons' law of friction i.e. the frictional force against the sliding motion of solid object is proportional to the loading force and not dependent on the contact area, holds well for various systems. Here we show, however, the breakdown of the Amontons' law for the elastic object which have local friction obeying Amontons' law and is under uniform pressure by FEM calculation The external shearing force applied to the trailing edge of the sample induces local slip. The range of the slip increases with the increasing external force adiabatically at first. When the range reaches the critical magnitude, the slips moves rapidly and reaches the leading edge of the sample then the whole system slides. These behaviors are consistent with the experiment by Rubinstein et.al. (Phys. Rev. Lett. 98, 226103). The static frictional coefficient, the ratio between the static frictional force for the whole system and the loading force, decreases with the increasing pressure. This means the breakdown of Amontons' law. The pressure dependence of the frictional coefficient is caused by the change of the critical length of the local slip. The behaviors of the local slip and the frictional coefficient are well explained by the 1 dimensional model analytically.

Transducer selection and application in magnetoacoustic tomography with magnetic induction

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

Zhou, Yuqi; Wang, Jiawei; Ma, Qingyu, E-mail: maqingyu@njnu.edu.cn

2016-03-07

As an acoustic receiver, transducer plays a vital role in signal acquisition and image reconstruction for magnetoacoustic tomography with magnetic induction (MAT-MI). In order to optimize signal acquisition, the expressions of acoustic pressure detection and waveform collection are theoretically studied based on the radiation theory of acoustic dipole and the reception pattern of transducer. Pressure distributions are simulated for a cylindrical phantom model using a planar piston transducer with different radii and bandwidths. The proposed theory is also verified by the experimental measurements of acoustic waveform detection for an aluminum foil cylinder. It is proved that acoustic pressure with sharpmore » and clear boundary peaks can be detected by the large-radius transducer with wide bandwidth, reflecting the differential of the induced Lorentz force accurately, which is helpful for precise conductivity reconstruction. To detect acoustic pressure with acceptable pressure amplitude, peak pressure ratio, amplitude ratio, and improved signal to noise ratio, the scanning radius of 5–10 times the radius of the object should be selected to improve the accuracy of image reconstruction. This study provides a theoretical and experimental basis for transducer selection and application in MAT-MI to obtain reconstructed images with improved resolution and definition.« less

Selection dynamic of Escherichia coli host in M13 combinatorial peptide phage display libraries.

PubMed

Zanconato, Stefano; Minervini, Giovanni; Poli, Irene; De Lucrezia, Davide

2011-01-01

Phage display relies on an iterative cycle of selection and amplification of random combinatorial libraries to enrich the initial population of those peptides that satisfy a priori chosen criteria. The effectiveness of any phage display protocol depends directly on library amino acid sequence diversity and the strength of the selection procedure. In this study we monitored the dynamics of the selective pressure exerted by the host organism on a random peptide library in the absence of any additional selection pressure. The results indicate that sequence censorship exerted by Escherichia coli dramatically reduces library diversity and can significantly impair phage display effectiveness.

Magnetic properties of Gd intermetallics

DOE PAGES

Petit, Leon; Szotek, Zdzislawa; Jackson, Jerome; ...

2017-04-06

Here, using first-principles calculations, based on disordered local moment theory, combined with the self-interaction corrected local spin density approximation, we study magnetic interactions in GdX intermetallics for X = Cu, Zn, Ga, Cd, and Mg. Our predicted magnetic orders and ordering temperatures both at zero and other pressures agree well with experiments including the large increase in the Curie temperature of GdCd under pressure that is shown by our own experimental measurements. From our results it emerges that the Ruderman-Kittel-Kasuya-Yosida interaction on its own can not explain the observed behaviour under pressure, and that the magnetic ordering mechanism is stronglymore » influenced by the occupations of both Gd and anion d-bands.« less

[The numerical simulation of the internal flow field inside the pressure generator of a continuous positive airway pressure ventilator].

PubMed

Cheng, Yunzhang; Zhu, Lihua; Zhang, Weiguo; Wu, Wenquan

2011-12-01

The problem of noise in ventilator has always been an important topic to study in the development of the ventilator. A great number of data are showing that there are still large gaps of research and application levels in noise control of the ventilator between China and some more advanced foreign countries. In this study, with cooperation of the Shanghai Medical Equipment Limited Liability Company, we used the computational fluid dynamics (CFD), software FLUENT, adopted the standard k-epsilon turbulence model and the SIMPLE algorithm to simulate the inner flow field of the continuous positive airway pressure (CPAP) ventilator's pressure generator. After a detailed analysis, we figured out that there are several deficiencies in this ventilator, like local reflow in volute, uneven velocity distribution and local negative pressure in inlet of the impeller, which easily lead to noise and affect the ventilator's performances. So, it needs to be improved to a certain extent.

Electronic and structural ground state of heavy alkali metals at high pressure

NASA Astrophysics Data System (ADS)

Fabbris, G.; Lim, J.; Veiga, L. S. I.; Haskel, D.; Schilling, J. S.

2015-02-01

Alkali metals display unexpected properties at high pressure, including emergence of low-symmetry crystal structures, which appear to occur due to enhanced electronic correlations among the otherwise nearly free conduction electrons. We investigate the high-pressure electronic and structural ground state of K, Rb, and Cs using x-ray absorption spectroscopy and x-ray diffraction measurements together with a b i n i t i o theoretical calculations. The sequence of phase transitions under pressure observed at low temperature is similar in all three heavy alkalis except for the absence of the o C 84 phase in Cs. Both the experimental and theoretical results point to pressure-enhanced localization of the valence electrons characterized by pseudogap formation near the Fermi level and strong s p d hybridization. Although the crystal structures predicted to host magnetic order in K are not observed, the localization process appears to drive these alkalis closer to a strongly correlated electron state.

Pressure-induced amorphization of YVO₄:Eu³⁺ nanoboxes.

PubMed

Ruiz-Fuertes, J; Gomis, O; León-Luis, S F; Schrodt, N; Manjón, F J; Ray, S; Santamaría-Pérez, D; Sans, J A; Ortiz, H M; Errandonea, D; Ferrer-Roca, C; Segura, A; Martínez-García, D; Lavín, V; Rodríguez-Mendoza, U R; Muñoz, A

2016-01-15

A structural transformation from the zircon-type structure to an amorphous phase has been found in YVO4:Eu(3+) nanoboxes at high pressures above 12.7 GPa by means of x-ray diffraction measurements. However, the pair distribution function of the high-pressure phase shows that the local structure of the amorphous phase is similar to the scheelite-type YVO4. These results are confirmed both by Raman spectroscopy and Eu(3+) photoluminescence which detect the phase transition to a scheelite-type structure at 10.1 and 9.1 GPa, respectively. The irreversibility of the phase transition is observed with the three techniques after a maximum pressure in the upstroke of around 20 GPa. The existence of two (5)D0-->(7)F0 photoluminescence peaks confirms the existence of two local environments for Eu(3+), at least for the low-pressure phase. One environment is the expected for substituting Y(3+) and the other is likely a disordered environment possibly found at the surface of the nanoboxes.

Flight-measured pressure characteristics of aft-facing steps in high Reynolds number flow at Mach numbers of 2.20, 2.50, and 2.80 and comparison with other data

NASA Technical Reports Server (NTRS)

Powers, S. G.

1978-01-01

The YF-12 airplane was studied to determine the pressure characteristics associated with an aft-facing step in high Reynolds number flow for nominal Mach numbers of 2.20, 2.50, and 2.80. Base pressure coefficients were obtained for three step heights. The surface static pressures ahead of and behind the step were measured for the no-step condition and for each of the step heights. A boundary layer rake was used to determine the local boundary layer conditions. The Reynolds number based on the length of flow ahead of the step was approximately 10 to the 8th power and the ratios of momentum thickness to step height ranged from 0.2 to 1.0. Base pressure coefficients were compared with other available data at similar Mach numbers and at ratios of momentum thickness to step height near 1.0. In addition, the data were compared with base pressure coefficients calculated by a semiempirical prediction method. The base pressure ratios are shown to be a function of Reynolds number based on momentum thickness. Profiles of the surface pressures ahead of and behind the step and the local boundary layer conditions are also presented.

Comparison of localized retinal nerve fiber layer defects between a low-teen intraocular pressure group and a high-teen intraocular pressure group in normal-tension glaucoma patients.

PubMed

Kim, Dong Myung; Seo, Je Hyun; Kim, Seok Hwan; Hwang, Seung-Sik

2007-05-01

To compare the features of localized retinal nerve fiber layer (RNFL) defects between a low-teen intraocular pressure (IOP) group and a high-teen IOP group in normal-tension glaucoma (NTG) patients. Seventy-seven eyes of 77 NTG patients showing localized RNFL defects on RNFL photographs and corresponding visual filed defects at the initial visit to a glaucoma specialist were selected for this study. Patients with range of diurnal IOP within low-teen or high-teen in both eyes were included. All participants completed refraction, diurnal IOP measurement, central corneal thickness (CCT) measurement, stereoscopic disc photography, RNFL photography, and automated perimetry. On RNFL photograph, approximation of the defect to the macula (angle alpha) and width of the defects (angle beta) were measured to represent RNFL defects. The patients were divided into 2 groups according to the level of IOP. A low-teen group had highest IOP of 15 mm Hg (group B). Age at diagnosis, percentage of male patients, systemic disease, refraction, CCT, highest IOP, angle alpha, angle beta, and mean deviation and pattern standard deviation of visual field were compared between the 2 groups. Age at diagnosis of NTG, age distribution, percentage of male patients, systemic disease, spherical equivalent of refraction, CCT, mean deviation, and pattern standard deviation were not different between the 2 groups. Highest IOP was 13.8+/-1.2 mm Hg in group A and 19.2+/-1.4 mm Hg in group B (P<0.001). Angle alpha was significantly smaller in group A than in group B (37.0+/-14.0 vs. 56.5+/-21.2 degrees, P<0.001), whereas angle beta was not different between the 2 groups (39.9+/-17.9 vs. 37.5+/-15.9 degrees, P=0.54). There were no significant correlations between spherical equivalent and angle alpha (r=-0.03, P=0.82), between spherical equivalent and angle beta (r=-0.04, P=0.74), and between angle alpha and angle beta (r=-0.21, P=0.07). Localized RNFL defect was closer to the center of the macula in group A than in group B, whereas width of defects was not different between the 2 groups. These findings provide indirect evidence to suggest that more than one pathogenic mechanism may exist in the development of RNFL defects in NTG.

Recombination of mitochondrial DNA without selection pressure among compatible strains of the Aspergillus niger species aggregate.

PubMed

Tóth, B; Hamari, Z; Ferenczy, L; Varga, J; Kevei, F

1998-03-01

Previous mitochondrial transmission experiments between oligomycin-resistant and oligomycin-sensitive incompatible strains of the A. niger aggregate bearing various mtDNA RFLP profiles resulted in a great variety of mitochondrial recombinants under selection pressure. Apart from the recombinant mtDNAs, resistant clones harbouring unchanged RFLP profiles of resistant donor mtDNAs with the recipient nuclear backgrounds were rarely isolated. These strains were anastomosed with nuclearly isogenic oligomycin-sensitive recipient partners and the mitochondria of the resulting progeny were examined under non-selective conditions. These experiments provide insights into events which are possibly similar to those occurring in nature. The heterokaryons obtained formed both oligomycin-resistant and -sensitive sectors, most of which were found to be homoplasmons. Progenies harbouring oligomycin-resistant and -sensitive mtDNAs may originate either from individual recombination events or be due to parental segregation. MtDNA recombination might take place in the heterokaryons without selection by oligomycin. The most frequent recombinant types of mtDNA RFLP profiles were indistinguishable from those recombinant mtDNAs which were frequently obtained under selection pressure from directed transfer experiments between incompatible strains. We present evidence that mixed mitochondrial populations may influence the compatibility reactions in the presence of an isogenic nuclear background, that recombination may take place without selection pressure, and that the process does not require specific nuclear sequences of both parental strains.

The Genetic Basis of Upland/Lowland Ecotype Divergence in Switchgrass (Panicum virgatum)

PubMed Central

Milano, Elizabeth R.; Lowry, David B.; Juenger, Thomas E.

2016-01-01

The evolution of locally adapted ecotypes is a common phenomenon that generates diversity within plant species. However, we know surprisingly little about the genetic mechanisms underlying the locally adapted traits involved in ecotype formation. The genetic architecture underlying locally adapted traits dictates how an organism will respond to environmental selection pressures, and has major implications for evolutionary ecology, conservation, and crop breeding. To understand the genetic architecture underlying the divergence of switchgrass (Panicum virgatum) ecotypes, we constructed a genetic mapping population through a four-way outbred cross between two northern upland and two southern lowland accessions. Trait segregation in this mapping population was largely consistent with multiple independent loci controlling the suite of traits that characterizes ecotype divergence. We assembled a joint linkage map using ddRADseq, and mapped quantitative trait loci (QTL) for traits that are divergent between ecotypes, including flowering time, plant size, physiological processes, and disease resistance. Overall, we found that most QTL had small to intermediate effects. While we identified colocalizing QTL for multiple traits, we did not find any large-effect QTL that clearly controlled multiple traits through pleiotropy or tight physical linkage. These results indicate that ecologically important traits in switchgrass have a complex genetic basis, and that similar loci may underlie divergence across the geographic range of the ecotypes. PMID:27613751

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

Barada, K., E-mail: kshitish@ucla.edu; Rhodes, T. L.; Crocker, N. A.

We present new measurements of internal magnetic fluctuations obtained with a novel eight channel cross polarization scattering (CPS) system installed on the DIII-D tokamak. Measurements of internal, localized magnetic fluctuations provide a window on an important physics quantity that we heretofore have had little information on. Importantly, these measurements provide a new ability to challenge and test linear and nonlinear simulations and basic theory. The CPS method, based upon the scattering of an incident microwave beam into the opposite polarization by magnetic fluctuations, has been significantly extended and improved over the method as originally developed on the Tore Supra tokamak.more » A new scattering geometry, provided by a unique probe beam, is utilized to improve the spatial localization and wavenumber range. Remotely controllable polarizer and mirror angles allow polarization matching and wavenumber selection for a range of plasma conditions. The quasi-optical system design, its advantages and challenges, as well as important physics validation tests are presented and discussed. Effect of plasma beta (ratio of kinetic to magnetic pressure) on both density and magnetic fluctuations is studied and it is observed that internal magnetic fluctuations increase with beta. During certain quiescent high confinement operational regimes, coherent low frequency modes not detected by magnetic probes are detected locally by CPS diagnostics.« less

Improving cancer treatment with cyclotron produced radionuclides. Progress report

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

Larson, S.M.; Finn, R.D.

1992-08-04

Our goal is to improve the scientific basis for tumor diagnosis, treatment and treatment follow-up based on the use of cyclotron produced radiotracers in oncology. The grant includes 3 interactive components: Radiochemistry/Cyclotron; Pharmacology; and Immunology. The radiochemistry group seeks to develop innovative cyclotron targetry, radiopharmaceuticals, and radiolabeled antibodies, which are then used to assess important unanswered questions in tumor pharmacology and immunology. Examples include selected positron emitting radionuclides, such as Iodine-124, and Ga-66; I-124, I-123, I-131 labeled iododeoxyuridine, C-11 colchicine, and antimetabolites, like C-11 methotrexate; and radiolabeled antibodies, 3F8, M195, A33, and MRK16 for application in the pharmacology and immunologymore » projects. The pharmacology program studies tumor resistance to chemotherapy, particularly the phenomenon of multidrug resistance and the relationship between tumor uptake and retention and the tumor response for anti-metabolite drugs. The immunology program studies the physiology of antibody localization at the tissue level as the basis for novel approaches to improving tumor localization such as through the use of an artificial lymphatic system which mechanically reduces intratumoral pressures in tumors in vivo. Quantitative imaging approaches based on PET and SPECT in radioimmunotherapy are studied to give greater insight into the physiology of tumor localization and dosimetry.« less

Improving cancer treatment with cyclotron produced radionuclides

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

Larson, S.M.; Finn, R.D.

1992-08-04

Our goal is to improve the scientific basis for tumor diagnosis, treatment and treatment follow-up based on the use of cyclotron produced radiotracers in oncology. The grant includes 3 interactive components: Radiochemistry/Cyclotron; Pharmacology; and Immunology. The radiochemistry group seeks to develop innovative cyclotron targetry, radiopharmaceuticals, and radiolabeled antibodies, which are then used to assess important unanswered questions in tumor pharmacology and immunology. Examples include selected positron emitting radionuclides, such as Iodine-124, and Ga-66; I-124, I-123, I-131 labeled iododeoxyuridine, C-11 colchicine, and antimetabolites, like C-11 methotrexate; and radiolabeled antibodies, 3F8, M195, A33, and MRK16 for application in the pharmacology and immunologymore » projects. The pharmacology program studies tumor resistance to chemotherapy, particularly the phenomenon of multidrug resistance and the relationship between tumor uptake and retention and the tumor response for anti-metabolite drugs. The immunology program studies the physiology of antibody localization at the tissue level as the basis for novel approaches to improving tumor localization such as through the use of an artificial lymphatic system which mechanically reduces intratumoral pressures in tumors in vivo. Quantitative imaging approaches based on PET and SPECT in radioimmunotherapy are studied to give greater insight into the physiology of tumor localization and dosimetry.« less

Restricted gene flow and fine-scale population structuring in tool using New Caledonian crows

NASA Astrophysics Data System (ADS)

Rutz, C.; Ryder, T. B.; Fleischer, R. C.

2012-04-01

New Caledonian crows Corvus moneduloides are the most prolific avian tool users. It has been suggested that some aspects of their complex tool use behaviour are under the influence of cultural processes, involving the social transmission—and perhaps even progressive refinement—of tool designs. Using microsatellite and mt-haplotype profiling of crows from three distinct habitats (dry forest, farmland and beachside habitat), we show that New Caledonian crow populations can exhibit significant fine-scale genetic structuring. Our finding that some sites of <10 km apart were highly differentiated demonstrates considerable potential for genetic and/or cultural isolation of crow groups. Restricted movement of birds between local populations at such small spatial scales, especially across habitat boundaries, illustrates how specific tool designs could be preserved over time, and how tool technologies of different crow groups could diverge due to drift and local selection pressures. Young New Caledonian crows have an unusually long juvenile dependency period, during which they acquire complex tool-related foraging skills. We suggest that the resulting delayed natal dispersal drives population-divergence patterns in this species. Our work provides essential context for future studies that examine the genetic makeup of crow populations across larger geographic areas, including localities with suspected cultural differences in crow tool technologies.

Selective pressure of antibiotic pollution on bacteria of importance to public health.

PubMed

Tello, Alfredo; Austin, Brian; Telfer, Trevor C

2012-08-01

Many bacteria of clinical importance survive and may grow in different environments. Antibiotic pollution may exert on them a selective pressure leading to an increase in the prevalence of resistance. In this study we sought to determine whether environmental concentrations of antibiotics and concentrations representing action limits used in environmental risk assessment may exert a selective pressure on clinically relevant bacteria in the environment. We used bacterial inhibition as an assessment end point to link antibiotic selective pressures to the prevalence of resistance in bacterial populations. Species sensitivity distributions were derived for three antibiotics by fitting log-logistic models to end points calculated from minimum inhibitory concentration (MIC) distributions based on worldwide data collated by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). To place bacteria represented in these distributions in a broader context, we performed a brief phylogenetic analysis. The potentially affected fraction of bacterial genera at measured environmental concentrations of antibiotics and environmental risk assessment action limits was used as a proxy for antibiotic selective pressure. Measured environmental concentrations and environmental risk assessment action limits were also directly compared to wild-type cut-off values. The potentially affected fraction of bacterial genera estimated based on antibiotic concentrations measured in water environments is ≤ 7%. We estimated that measured environmental concentrations in river sediments, swine feces lagoons, liquid manure, and farmed soil inhibit wild-type populations in up to 60%, 92%, 100%, and 30% of bacterial genera, respectively. At concentrations used as action limits in environmental risk assessment, erythromycin and ciprofloxacin were estimated to inhibit wild-type populations in up to 25% and 76% of bacterial genera. Measured environmental concentrations of antibiotics, as well as concentrations representing environmental risk assessment action limits, are high enough to exert a selective pressure on clinically relevant bacteria that may lead to an increase in the prevalence of resistance.

Skin blood flow with elastic compressive extravehicular activity space suit.

PubMed

Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R

2003-10-01

During extravehicular activity (EVA), current space suits are pressurized with 100% oxygen at approximately 222 mmHg. A tight elastic garment, or mechanical counter pressure (MCP) suit that generates pressure by compression, may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with negative ambient pressure with an MCP sleeve. The MCP glove and sleeve generated pressures similar to the current space suit. MCP remained constant during negative pressure due to unchanged elasticity of the material. Decreased skin capillary blood flow and temperature during MCP compression was counteracted by greater negative pressure or a smaller pressure differential.

Virtual water trade patterns in relation to environmental and socioeconomic factors: a case study for Tunisia

NASA Astrophysics Data System (ADS)

Chouchane, Hatem; Krol, Maarten; Hoekstra, Arjen

2016-04-01

Water scarcity is among the main problems faced by many societies. Growing water demands put increasing pressure on local water resources, especially in water-short countries. Virtual water trade can play a key role in filling the gap between local demands and supply. This study aims to analyze the changes in virtual water trade of Tunisia in relation to environmental and socio-economic factors such as GDP, irrigated land, precipitation, population and water scarcity. The water footprint is estimated using Aquacrop for six crops over the period 1981-2010 at daily basis and a spatial resolution of 5 by 5 arc minutes. Virtual water trade is quantified at yearly basis. Regression models are used to investigate changes in virtual water trade in relation to various environmental and socio-economic factors. The explaining variables are selected in order to help understanding the trend and the inter-annual variability of the net virtual water import; GDP, population and irrigated land are hypothesized to explain the trend, and precipitation and water scarcity to explain variability. The selected crops are divided into three baskets. The first basket includes the two most imported crops, which are mainly rain-fed (wheat and barley). The second basket contains the two most exported crops, which are both irrigated and rain-fed (olives and dates). In the last basket we find the two highest economic blue water productive crops, which are mainly irrigated (tomatoes and potatoes). The results show the impact of each factor on net virtual water import of the selected crops during the period 1981-2010. Keywords: Virtual water, trade patterns, Aquacrop, Tunisia, water scarcity, water footprint.

Can local adaptation research in plants inform selection of native plant materials? An analysis of experimental methodologies

USDA-ARS?s Scientific Manuscript database

Local adaptation research in plants: limitations to synthetic understanding Local adaptation is used as a criterion to select plant materials that will display high fitness in new environments. A large body of research has explored local adaptation in plants, however, to what extent findings can inf...

Drivers, dynamics, and control of emerging vector-borne zoonotic diseases

PubMed Central

Kilpatrick, A. Marm; Randolph, Sarah E.

2013-01-01

Emerging vector-borne diseases represent an important issue for global health. Many vector-borne pathogens have appeared in new regions in the past two decades, and many endemic diseases have increased in incidence. Although introductions and local emergence are frequently considered distinct processes, many emerging endemic pathogens are in fact invading at a local scale coincident with habitat change. We highlight key differences in the dynamics and disease burden that result from increased pathogen transmission following habitat change compared with the introduction of pathogens to new regions. Truly in situ emergence is commonly driven by changes in human factors as much as by enhanced enzootic cycles whereas pathogen invasion results from anthropogenic trade and travel and suitable conditions for a pathogen, including hosts, vectors, and climate. Once established, ecological factors related to vector characteristics shape the evolutionary selective pressure on pathogens that may result in increased use of humans as transmission hosts. We describe challenges inherent in the control of vector-borne zoonotic diseases and some emerging non-traditional strategies that may be more effective in the long term. PMID:23200503

Attitudes of local communities towards conservation of mangrove forests: A case study from the east coast of India

NASA Astrophysics Data System (ADS)

Badola, Ruchi; Barthwal, Shivani; Hussain, Syed Ainul

2012-01-01

The ecological and economic importance of mangrove ecosystems is well established and highlighted by studies establishing a correlation between the protective function of mangroves and the loss of lives and property caused by coastal hazards. Nevertheless, degradation of this ecosystem remains a matter of concern, emphasizing the fact that effective conservation of natural resources is possible only with an understanding of the attitudes and perceptions of local communities. In the present study, we examined the attitudes and perceptions of local communities towards mangrove forests through questionnaire surveys in 36 villages in the Bhitarkanika Conservation Area, India. The sample villages were selected from 336 villages using hierarchical cluster analysis. The study revealed that local communities in the area had positive attitudes towards conservation and that their demographic and socio-economic conditions influenced people's attitudes. Local communities valued those functions of mangrove forests that were directly linked to their wellbeing. Despite human-wildlife conflict, the attitudes of the local communities were not altogether negative, and they were willing to participate in mangrove restoration. People agreed to adopt alternative resources if access to forest resources were curtailed. Respondents living near the forests, who could not afford alternatives, admitted that they would resort to pilfering. Hence, increasing their livelihood options may reduce the pressure on mangrove forests. In contrast with other ecosystems, the linkages of mangrove ecosystem services with local livelihoods and security are direct and tangible. It is therefore possible to develop strong local support for sustainable management of mangrove forests in areas where a positive attitude towards mangrove conservation prevails. The current debates on Reducing Emissions from Deforestation and Forest Degradation (REDD) and payment for ecosystem services provide ample scope for development of sustainable livelihood options for local communities from the conservation of critical ecosystems such as mangroves.

Nonmonotonic pressure evolution of the upper critical field in superconducting FeSe

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

Kaluarachchi, Udhara S.; Taufour, Valentin; Böhmer, Anna E.

2016-02-01

The pressure dependence of the upper critical field, H c2,c, of single crystalline FeSe was studied using measurements of the interplane resistivity, ρ c, in magnetic fields parallel to tetragonal c axis. H c2,c(T) curves obtained under hydrostatic pressures up to 1.56 GPa, the range over which the superconducting transition temperature, T c, of FeSe exhibits a nonmonotonic dependence with local maximum at p 1 ≈ 0.8 GPa and local minimum at p 2 ≈ 1.2 GPa. The slope of the upper critical field at T c,(dH c2,c/dT)T c, also exhibits a nonmonotonic pressure dependence with distinct changes at pmore » 1 and p 2. For p < p 1 the slope can be described within a multiband orbital model. For both p 1 < p < p 2 and p > p 2 the slope is in good semiquantitative agreement with a single band, orbital Helfand-Werthamer theory with Fermi velocities determined from Shubnikov–de Haas measurements. Lastly, this finding indicates that Fermi surface changes are responsible for the local minimum of T c(p) at p 2 ≈ 1.2 GPa.« less

Which medical device and/or which local treatment for prevention in patients with risk factors for pressure sores in 2012? Developing French guidelines for clinical practice.

PubMed

Nicolas, B; Moiziard, A S; Barrois, B; Colin, D; Michel, J M; Passadori, Y; Ribinik, P

2012-10-01

Implementation of a prevention strategy after the identification of risk factors is essential at the entrance in a care unit or in a medical-social unit. Determine which medical devices and which treatments may be used in order to prevent pressure sore in 2012. Systematic review of the literature using databases: Pascal, Biomed, PubMed, and Cochrane library between 2000 and 2010. Nursing care including use of soft product, non-irritating for the cleaning, hydration of the skin with emollients, protection of fragile skin in case of incontinence by applying a skin protector and application of dressings in front of bony prominences to reduce shear forces, remain valid (level C). Nursing cares and use of dressing in patients with high risks of pressure sores are the responsibility of the nurses. The engagement of health care teams involves screening of risk factors and the knowledge of treatments and local devices. Local preventive treatment in a patient with risk factors of pressure sore is of great interest at entrance in a care unit or in a medical-social unit. Copyright © 2012. Published by Elsevier Masson SAS.

Introducing the Pressure-Sensing Palatograph--The Next Frontier in Electropalatography

ERIC Educational Resources Information Center

Murdoch, Bruce; Goozee, Justine; Veidt, Martin; Scott, Dion; Meyers, Ian

2004-01-01

Primary Objective. To extend the capabilities of current electropalatography (EPG) systems by developing a pressure-sensing EPG system. An initial trial of a prototype pressure-sensing palate will be presented. Research Design. The processes involved in designing the pressure sensors are outlined, with Hall effect transistors being selected. These…

Development of a system to measure local measurement conditions around textile electrodes.

PubMed

Kim, Saim; Oliveira, Joana; Roethlingshoefer, Lisa; Leonhard, Steffen

2010-01-01

The three main influence factors on the interface between textile electrode an skin are: temperature, contact pressure and relative humidity. This paper presents first results of a prototype, which measures these local measurement conditions around textile electrodes. The wearable prototype is a data acquisition system based on a microcontroller with a flexible sensor sleeve. Validation measurements included variation of ambient temperature, contact pressures and sleeve material. Results show a good correlation with data found in literature.

Summary of experimental heat-transfer results from the turbine hot section facility

NASA Technical Reports Server (NTRS)

Gladden, Herbert J.; Yeh, Fredrick C.

1993-01-01

Experimental data from the turbine Hot Section Facility are presented and discussed. These data include full-coverage film-cooled airfoil results as well as special instrumentation results obtained at simulated real engine conditions. Local measurements of airfoil wall temperature, airfoil gas-path static-pressure distribution, and local heat-transfer coefficient distributions are presented and discussed. In addition, measured gas and coolant temperatures and pressures are presented. These data are also compared with analyses from Euler and boundary-layer codes.

On modeling pressure diffusion in non-homogeneous shear flows

NASA Technical Reports Server (NTRS)

Demuren, A. O.; Rogers, M. M.; Durbin, P.; Lele, S. K.

1996-01-01

New models are proposed for the 'slow and 'rapid' parts of the pressure diffusive transport based on the examination of DNS databases for plane mixing layers and wakes. The model for the 'slow' part is non-local, but requires the distribution of the triple-velocity correlation as a local source. The latter can be computed accurately for the normal component from standard gradient diffusion models, but such models are inadequate for the cross component. More work is required to remedy this situation.

Determination of local values of gas and liquid mass flux in highly loaded two-phase flow

NASA Technical Reports Server (NTRS)

Burick, R. J.; Scheuerman, C. H.; Falk, A. Y.

1974-01-01

A measurement system using a deceleration probe was designed for determining the local values of gas and liquid mass flux in various gas/liquid droplet sprayfields. The system was used to characterize two-phase flowfields generated by gas/liquid rocket-motor injectors. Measurements were made at static pressures up to 500 psia and injected mass flow ratios up to 20. The measurement system can also be used at higher pressures and in gas/solid flowfields.

Local projection stabilization for linearized Brinkman-Forchheimer-Darcy equation

NASA Astrophysics Data System (ADS)

Skrzypacz, Piotr

2017-09-01

The Local Projection Stabilization (LPS) is presented for the linearized Brinkman-Forchheimer-Darcy equation with high Reynolds numbers. The considered equation can be used to model porous medium flows in chemical reactors of packed bed type. The detailed finite element analysis is presented for the case of nonconstant porosity. The enriched variant of LPS is based on the equal order interpolation for the velocity and pressure. The optimal error bounds for the velocity and pressure errors are justified numerically.

Timing of favorable conditions, competition and fertility interact to govern recruitment of invasive Chinese tallow tree in stressful environments.

PubMed

Gabler, Christopher A; Siemann, Evan

2013-01-01

The rate of new exotic recruitment following removal of adult invaders (reinvasion pressure) influences restoration outcomes and costs but is highly variable and poorly understood. We hypothesize that broad variation in average reinvasion pressure of Triadica sebifera (Chinese tallow tree, a major invader) arises from differences among habitats in spatiotemporal availability of realized recruitment windows. These windows are periods of variable duration long enough to permit establishment given local environmental conditions. We tested this hypothesis via a greenhouse mesocosm experiment that quantified how the duration of favorable moisture conditions prior to flood or drought stress (window duration), competition and nutrient availability influenced Triadica success in high stress environments. Window duration influenced pre-stress seedling abundance and size, growth during stress and final abundance; it interacted with other factors to affect final biomass and germination during stress. Stress type and competition impacted final size and biomass, plus germination, mortality and changes in size during stress. Final abundance also depended on competition and the interaction of window duration, stress type and competition. Fertilization interacted with competition and stress to influence biomass and changes in height, respectively, but did not affect Triadica abundance. Overall, longer window durations promoted Triadica establishment, competition and drought (relative to flood) suppressed establishment, and fertilization had weak effects. Interactions among factors frequently produced different effects in specific contexts. Results support our 'outgrow the stress' hypothesis and show that temporal availability of abiotic windows and factors that influence growth rates govern Triadica recruitment in stressful environments. These findings suggest that native seed addition can effectively suppress superior competitors in stressful environments. We also describe environmental scenarios where specific management methods may be more or less effective. Our results enable better niche-based estimates of local reinvasion pressure, which can improve restoration efficacy and efficiency by informing site selection and optimal management.

Timing of Favorable Conditions, Competition and Fertility Interact to Govern Recruitment of Invasive Chinese Tallow Tree in Stressful Environments

PubMed Central

Gabler, Christopher A.; Siemann, Evan

2013-01-01

The rate of new exotic recruitment following removal of adult invaders (reinvasion pressure) influences restoration outcomes and costs but is highly variable and poorly understood. We hypothesize that broad variation in average reinvasion pressure of Triadica sebifera (Chinese tallow tree, a major invader) arises from differences among habitats in spatiotemporal availability of realized recruitment windows. These windows are periods of variable duration long enough to permit establishment given local environmental conditions. We tested this hypothesis via a greenhouse mesocosm experiment that quantified how the duration of favorable moisture conditions prior to flood or drought stress (window duration), competition and nutrient availability influenced Triadica success in high stress environments. Window duration influenced pre-stress seedling abundance and size, growth during stress and final abundance; it interacted with other factors to affect final biomass and germination during stress. Stress type and competition impacted final size and biomass, plus germination, mortality and changes in size during stress. Final abundance also depended on competition and the interaction of window duration, stress type and competition. Fertilization interacted with competition and stress to influence biomass and changes in height, respectively, but did not affect Triadica abundance. Overall, longer window durations promoted Triadica establishment, competition and drought (relative to flood) suppressed establishment, and fertilization had weak effects. Interactions among factors frequently produced different effects in specific contexts. Results support our ‘outgrow the stress’ hypothesis and show that temporal availability of abiotic windows and factors that influence growth rates govern Triadica recruitment in stressful environments. These findings suggest that native seed addition can effectively suppress superior competitors in stressful environments. We also describe environmental scenarios where specific management methods may be more or less effective. Our results enable better niche-based estimates of local reinvasion pressure, which can improve restoration efficacy and efficiency by informing site selection and optimal management. PMID:23967212

Surface Damage and Treatment by Impact of a Low Temperature Nitrogen Jet

NASA Astrophysics Data System (ADS)

Laribou, Hicham; Fressengeas, Claude; Entemeyer, Denis; Jeanclaude, Véronique; Tazibt, Abdel

2011-01-01

Nitrogen jets under high pressure and low temperature have been introduced recently. The process consists in projecting onto a surface a low temperature jet obtained from releasing the liquid nitrogen stored in a high pressure tank (e.g. 3000 bars) through a nozzle. It can be used in a range of industrial applications, including surface treatment or material removal through cutting, drilling, striping and cleaning. The process does not generate waste other than the removed matter, and it only releases neutral gas into the atmosphere. This work is aimed at understanding the mechanisms of the interaction between the jet and the material surface. Depending on the impacted material, the thermo-mechanical shock and blast effect induced by the jet can activate a wide range of damage mechanisms, including cleavage, crack nucleation and spalling, as well as void expansion and localized ductile failure. The test parameters (standoff distance, dwell time, operating pressure) play a role in selecting the dominant damage mechanism, but combinations of these various modes are usually present. Surface treatment through phase transformation or grain fragmentation in a layer below the surface can also be obtained by adequate tuning of the process parameters. In the current study, work is undertaken to map the damage mechanisms in metallic materials as well as the influence of the test parameters on damage, along with measurements of the thermo-mechanical conditions (impact force, temperature) in the impacted area.

Selection and static calibration of the Marsh J1678 pressure gauge

NASA Technical Reports Server (NTRS)

Oxendine, Charles R.; Smith, Howard W.

1993-01-01

During the experimental testing of the ultralight, it was determined that a pressure gauge would be required to monitor the simulated flight loads. After analyzing several factors, which are indicated in the discussion section of this report, the Marsh J1678 pressure gauge appeared to be the prominent candidate for the task. However, prior to the final selection, the Marsh pressure gauge was calibrated twice by two different techniques. As a result of the calibration, the Marsh gauge was selected as the appropriate measuring device during the structural testing of the ultralight. Although, there are commerical pressure gauges available on the market that would have proven to be more efficient and accurate. However, in order to obtain these characteristics in a gauge, one has to pay the price on the price tag, and this value is an exponential function of the degree of accuracy efficiency, precision, and many other features that may be designed into the gauge. After analyzing the extent of precision and accuracy that would be required, a more expensive gauge wouldn't have proven to be a financial benefit towards the outcome of the experiment.

Geographical variation in parasitism shapes larval immune function in a phytophagous insect

NASA Astrophysics Data System (ADS)

Vogelweith, Fanny; Dourneau, Morgane; Thiéry, Denis; Moret, Yannick; Moreau, Jérôme

2013-12-01

Two of the central goals of immunoecology are to understand natural variation in the immune system among populations and to identify those selection pressures that shape immune traits. Maintenance of the immune system can be costly, and both food quality and parasitism selection pressure are factors potentially driving immunocompetence. In tritrophic interactions involving phytophagous insects, host plants, and natural enemies, the immunocompetence of phytophagous insects is constrained by selective forces from both the host plants and the natural enemies. Here, we assessed the roles of host plants and natural enemies as selective pressures on immune variation among natural populations of Lobesia botrana. Our results showed marked geographical variation in immune defenses and parasitism among different natural populations. Larval immune functions were dependent of the host plant quality and were positively correlated to parasitism, suggesting that parasitoids select for greater investment into immunity in moth. Furthermore, investment in immune defense was negatively correlated with body size, suggesting that it is metabolically expensive. The findings emphasize the roles of host plants and parasitoids as selective forces shaping host immune functions in natural conditions. We argue that kinds of study are central to understanding natural variations in immune functions, and the selective forces beyond.

Mutation-profile-based methods for understanding selection forces in cancer somatic mutations: a comparative analysis.

PubMed

Zhou, Zhan; Zou, Yangyun; Liu, Gangbiao; Zhou, Jingqi; Wu, Jingcheng; Zhao, Shimin; Su, Zhixi; Gu, Xun

2017-08-29

Human genes exhibit different effects on fitness in cancer and normal cells. Here, we present an evolutionary approach to measure the selection pressure on human genes, using the well-known ratio of the nonsynonymous to synonymous substitution rate in both cancer genomes ( C N / C S ) and normal populations ( p N / p S ). A new mutation-profile-based method that adopts sample-specific mutation rate profiles instead of conventional substitution models was developed. We found that cancer-specific selection pressure is quite different from the selection pressure at the species and population levels. Both the relaxation of purifying selection on passenger mutations and the positive selection of driver mutations may contribute to the increased C N / C S values of human genes in cancer genomes compared with the p N / p S values in human populations. The C N / C S values also contribute to the improved classification of cancer genes and a better understanding of the onco-functionalization of cancer genes during oncogenesis. The use of our computational pipeline to identify cancer-specific positively and negatively selected genes may provide useful information for understanding the evolution of cancers and identifying possible targets for therapeutic intervention.

Ultrafast eclogite formation via melting-induced overpressure

NASA Astrophysics Data System (ADS)

Chu, Xu; Ague, Jay J.; Podladchikov, Yury Y.; Tian, Meng

2017-12-01

The conventional wisdom holds that metamorphic reactions take place at pressures near-lithostatic so that the thermodynamic pressure, reflected by the mineral assemblage, is directly correlated with depth. On the other hand, recent field-based observations and geodynamic simulations suggest that heterogeneous stress and significant pressure deviations above lithostatic (overpressure) can occur in Earth's crust. Here we show that eclogite, normally interpreted to form at great depths in subduction zones and Earth's mantle, may form at much shallower depths via local overpressure generated in crustal shear zones. The eclogites studied crop out as lenses hosted by felsic paragneiss in a sheared thrust slice and represent a local pressure and temperature anomaly in the Taconic orogenic belt, southern New England. Sharply-defined chemical zones in garnet, which record ∼5 kbar pressure rise and fall accompanied by a temperature increase of 150-200 °C, demonstrate extremely short timescales of diffusion. This requires anomalously fast compression (∼500 yrs) and decompression. We use coupled phase equilibria and garnet diffusion forward modeling to fit the observed garnet profiles and test the likely P- T- t paths using a Monte Carlo-type approach, accounting for off-center sectioning of garnet. The simulation shows that a ∼5 kbar pressure increase after the temperature peak is necessary to reproduce the garnet zoning. Remarkably, this post-peak-T compression (from 9 kbar to 14 kbar) lasted only ∼500 yrs. If the compression was due to burial along a lithostatic pressure gradient, the descent speed would exceed 30 m yr-1, defying any observed or modeled subduction rates. Local overpressure in response to partial melting in a confined volume (Vrijmoed et al., 2009) caused by transient shear heating can explain the ultra-fast compression without necessitating burial to great depth.

Two-order-parameter description of liquid Al under five different pressures

NASA Astrophysics Data System (ADS)

Li, Y. D.; Hao, Qing-Hai; Cao, Qi-Long; Liu, C. S.

2008-11-01

In the present work, using the glue potential, the constant pressure molecular-dynamics simulations of liquid Al under five various pressures and a systematic analysis of the local atomic structures have been performed in order to test the two-order-parameter model proposed by Tanaka [Phys. Rev. Lett. 80, 5750 (1998)] originally for explaining the unusual behaviors of liquid water. The temperature dependence of the bond order parameter Q6 in liquid Al under five different pressures can be well fitted by the functional expression (Q6)/(1-Q6)=Q60exp((ΔE-PΔV)/(kBT)) which produces the energy gain ΔE and the volume change upon the formation of a locally favored structure: ΔE=0.025eV and ΔV=-0.27(Å)3 . ΔE is nearly equal to the difference between the average bond energy of the other type I bonds and the average bond energy of 1551 bonds (characterizing the icosahedronlike local structure); ΔV could be explained as the average volume occupied by one atom in icosahedra minus that occupied by one atom in other structures. With the obtained ΔE and ΔV , it is satisfactorily explained that the density of liquid Al displays a much weaker nonlinear dependence on temperature under lower pressures. So it is demonstrated that the behavior of liquid Al can be well described by the two-order-parameter model.

Pressure distribution for the wing of the YAV-8B airplane; with and without pylons

NASA Technical Reports Server (NTRS)

Saltzman, Edwin J.; Delfrate, John H.; Sabsay, Catherine M.; Yarger, Jill M.

1992-01-01

Pressure distribution data have been obtained in flight at four span stations on the wing panel of the YAV-8B airplane. Data obtained for the supercritical profiled wing, with and without pylons installed, ranged from Mach 0.46 to 0.88. The altitude ranged from approximately 20,000 to 40,000 ft and the resultant Reynolds numbers varied from approximately 7.2 million to 28.7 million based on the mean aerodynamic chord. Pressure distribution data and flow visualization results show that the full-scale flight wing performance is compromised because the lower surface cusp region experiences flow separation for some important transonic flight conditions. This condition is aggravated when local shocks occur on the lower surface of the wing (mostly between 20 and 35 percent chord) when the pylons are installed for Mach 0.8 and above. There is evidence that convex fairings, which cover the pylon attachment flanges, cause these local shocks. Pressure coefficients significantly more negative than those for sonic flow also occur farther aft on the lower surface (near 60 percent chord) whether or not the pylons are installed for Mach numbers greater than or equal to 0.8. These negative pressure coefficient peaks and associated local shocks would be expected to cause increasing wave and separation drag at transonic Mach number increases.

Liquid Propulsion: Propellant Feed System Design. Chapter 2.3.11

NASA Technical Reports Server (NTRS)

Cannon, James L.

2010-01-01

The propellant feed system of a liquid rocket engine determines how the propellants are delivered from the tanks to the thrust chamber. They are generally classified as either pressure fed or pump fed. The pressure-fed system is simple and relies on tank pressures to feed the propellants into the thrust chamber. This type of system is typically used for space propulsion applications and auxiliary propulsion applications requiring low system pressures and small quantities of propellants. In contrast, the pump-fed system is used for high pressure, high performance applications. The selection of one propellant feed system over another is determined based on design trade studies at both the engine and vehicle levels. This chapter first provides a brief overview of the basic configurations of pressure-fed systems. Pump-fed systems are then discussed with greater detail given to the turbomachinery design. Selected design requirements and configurations are provided.

Special report: Occlusive cuff controller

NASA Technical Reports Server (NTRS)

Baker, J. T.

1975-01-01

A mechanical occlusive cuff controller suitable for blood flow experiments in space shuttle flights is described. The device requires 115 volt ac power and a pressurized gas source. Two occluding cuff pressures (30 and 50 mmHg) are selectable by a switch on the front panel. A screw driver adjustment allows accurate cuff pressurization levels for under or oversized limbs. Two pressurization cycles (20 second and 2 minutes) can be selected by a front panel switch. Adjustment of the timing cycles is also available through the front panel. A pushbutton hand switch allows remote start of the cuff inflation cycle. A stop/reset switch permits early termination of the cycle and disabling of the controller to prevent inadvertent reactivation. Pressure in the cuff is monitored by a differential aneroid barometer. In addition, an electrocardiogram trigger circuit permits the initiation of the pressurization cycle by an externally supplied ECG cycle.

Pressures generated in vitro during Stabident intraosseous injections.

PubMed

Whitworth, J M; Ramlee, R A M; Meechan, J G

2005-05-01

To test the hypothesis that the Stabident intraosseous injection is a potentially high-pressure technique, which carries serious risks of anaesthetic cartridge failure. A standard Astra dental syringe was modified to measure the internal pressure of local anaesthetic cartridges during injection. Intra-cartridge pressures were measured at 1 s intervals during slow (approximately 15 s) and rapid (<10 s) injections of 2% Xylocaine with 1:80,000 adrenaline (0.25 cartridge volumes) into air (no tissue resistance), or into freshly prepared Stabident perforation sites in the anterior mandible of freshly culled young and old sheep (against tissue resistance). Each injection was repeated 10 times over 3 days. Absolute maximum pressures generated by each category of injection, mean pressures at 1 s intervals in each series of injections, and standard deviations were calculated. Curves of mean maximum intra-cartridge pressure development with time were plotted for slow and rapid injections, and one-way anova (P<0.05) conducted to determine significant differences between categories of injection. Pressures created when injecting into air were less than those needed to inject into tissue (P<0.001). Fast injection produced greater intra-cartridge pressures than slow delivery (P<0.05). Injection pressures rose more quickly and to higher levels in small, young sheep mandibles than in larger, old sheep mandibles. The absolute maximum intra-cartridge pressure developed during the study was 3.31 MPa which is less than that needed to fracture glass cartridges. Stabident intraosseous injection conducted in accordance with the manufacturer's instructions does not present a serious risk of dangerous pressure build-up in local anaesthetic cartridges.

Phylogenetic divergence of cell biological features

PubMed Central

2018-01-01

Most cellular features have a range of states, but understanding the mechanisms responsible for interspecific divergence is a challenge for evolutionary cell biology. Models are developed for the distribution of mean phenotypes likely to evolve under the joint forces of mutation and genetic drift in the face of constant selection pressures. Mean phenotypes will deviate from optimal states to a degree depending on the effective population size, potentially leading to substantial divergence in the absence of diversifying selection. The steady-state distribution for the mean can even be bimodal, with one domain being largely driven by selection and the other by mutation pressure, leading to the illusion of phenotypic shifts being induced by movement among alternative adaptive domains. These results raise questions as to whether lineage-specific selective pressures are necessary to account for interspecific divergence, providing a possible platform for the establishment of null models for the evolution of cell-biological traits. PMID:29927740

Continuous-Reading Cryogen Level Sensor

NASA Technical Reports Server (NTRS)

Barone, F. E.; Fox, E.; Macumber, S.

1984-01-01

Two pressure transducers used in system for measuring amount of cryogenic liquid in tank. System provides continuous measurements accurate within 0.03 percent. Sensors determine pressure in liquid and vapor in tank. Microprocessor uses pressure difference to compute mass of cryogenic liquid in tank. New system allows continuous sensing; unaffected by localized variations in composition and density as are capacitance-sensing schemes.

Pressure Dependence of Coherence-Incoherence Crossover Behavior in KFe 2As 2 Observed by Resistivity and 75As-NMR/NQR.

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

Wiecki, P.; Taufour, V.; Chung, D. Y.

We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KFe 2As 2 under pressure (p). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T *). T * is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3d orbitalderived bands with the itinerant electron bands. No anomaly in T * is seen at the critical pressure pc = 1.8 GPa where a change ofmore » slope of the superconducting (SC) transition temperature Tc(p) has been observed. In contrast, Tc(p) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1/T1 data, although such a correlation cannot be seen in the replacement effects of A in the KFe 2As 2 (A = K, Rb, Cs) family. In the superconducting state, two T1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T1s indicates a nearly gapless state below Tc. On the other hand, the temperature dependence of the long component 1/T1L implies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe 2As 2 under pressure.« less

Pressure dependence of coherence-incoherence crossover behavior in KFe 2 As 2 observed by resistivity and As 75 -NMR/NQR

DOE PAGES

Wiecki, P.; Taufour, V.; Chung, D. Y.; ...

2018-02-13

We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KF e2 As 2 under pressure (p). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T 1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T*). T* is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3d orbital-derived bands with the itinerant electron bands. No anomaly in T* is seen at the critical pressure p c= 1.8 GPa where a change of slopemore » of the superconducting (SC) transition temperature T c( p ) has been observed. In contrast, T c( p ) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1/T 1 data, although such a correlation cannot be seen in the replacement effects of A in the AFe 2As 2 (A=K,Rb,Cs) family. In the superconducting state, two T 1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T 1s indicates a nearly gapless state below T c. On the other hand, the temperature dependence of the long component 1/T 1Limplies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe 2As 2 under pressure.« less

Pressure dependence of coherence-incoherence crossover behavior in KFe 2 As 2 observed by resistivity and As 75 -NMR/NQR

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

Wiecki, P.; Taufour, V.; Chung, D. Y.

We present the results of 75As nuclear magnetic resonance (NMR), nuclear quadrupole resonance (NQR), and resistivity measurements in KF e2 As 2 under pressure (p). The temperature dependence of the NMR shift, nuclear spin-lattice relaxation time (T 1), and resistivity show a crossover between a high-temperature incoherent, local-moment behavior and a low-temperature coherent behavior at a crossover temperature (T*). T* is found to increase monotonically with pressure, consistent with increasing hybridization between localized 3d orbital-derived bands with the itinerant electron bands. No anomaly in T* is seen at the critical pressure p c= 1.8 GPa where a change of slopemore » of the superconducting (SC) transition temperature T c( p ) has been observed. In contrast, T c( p ) seems to correlate with antiferromagnetic spin fluctuations in the normal state as measured by the NQR 1/T 1 data, although such a correlation cannot be seen in the replacement effects of A in the AFe 2As 2 (A=K,Rb,Cs) family. In the superconducting state, two T 1 components are observed at low temperatures, suggesting the existence of two distinct local electronic environments. The temperature dependence of the short T 1s indicates a nearly gapless state below T c. On the other hand, the temperature dependence of the long component 1/T 1Limplies a large reduction in the density of states at the Fermi level due to the SC gap formation. These results suggest a real-space modulation of the local SC gap structure in KFe 2As 2 under pressure.« less

Sexual networks: measuring sexual selection in structured, polyandrous populations.

PubMed

McDonald, Grant C; James, Richard; Krause, Jens; Pizzari, Tommaso

2013-03-05

Sexual selection is traditionally measured at the population level, assuming that populations lack structure. However, increasing evidence undermines this approach, indicating that intrasexual competition in natural populations often displays complex patterns of spatial and temporal structure. This complexity is due in part to the degree and mechanisms of polyandry within a population, which can influence the intensity and scale of both pre- and post-copulatory sexual competition. Attempts to measure selection at the local and global scale have been made through multi-level selection approaches. However, definitions of local scale are often based on physical proximity, providing a rather coarse measure of local competition, particularly in polyandrous populations where the local scale of pre- and post-copulatory competition may differ drastically from each other. These limitations can be solved by social network analysis, which allows us to define a unique sexual environment for each member of a population: 'local scale' competition, therefore, becomes an emergent property of a sexual network. Here, we first propose a novel quantitative approach to measure pre- and post-copulatory sexual selection, which integrates multi-level selection with information on local scale competition derived as an emergent property of networks of sexual interactions. We then use simple simulations to illustrate the ways in which polyandry can impact estimates of sexual selection. We show that for intermediate levels of polyandry, the proposed network-based approach provides substantially more accurate measures of sexual selection than the more traditional population-level approach. We argue that the increasing availability of fine-grained behavioural datasets provides exciting new opportunities to develop network approaches to study sexual selection in complex societies.

Numerical Simulation of Non-Thermal Food Preservation

NASA Astrophysics Data System (ADS)

Rauh, C.; Krauss, J.; Ertunc, Ö.; Delgado, a.

2010-09-01

Food preservation is an important process step in food technology regarding product safety and product quality. Novel preservation techniques are currently developed, that aim at improved sensory and nutritional value but comparable safety than in conventional thermal preservation techniques. These novel non-thermal food preservation techniques are based for example on high pressures up to one GPa or pulsed electric fields. in literature studies the high potential of high pressures (HP) and of pulsed electric fields (PEF) is shown due to their high retention of valuable food components as vitamins and flavour and selective inactivation of spoiling enzymes and microorganisms. for the design of preservation processes based on the non-thermal techniques it is crucial to predict the effect of high pressure and pulsed electric fields on the food components and on the spoiling enzymes and microorganisms locally and time-dependent in the treated product. Homogenous process conditions (especially of temperature fields in HP and PEF processing and of electric fields in PEF) are aimed at to avoid the need of over-processing and the connected quality loss and to minimize safety risks due to under-processing. the present contribution presents numerical simulations of thermofluiddynamical phenomena inside of high pressure autoclaves and pulsed electric field treatment chambers. in PEF processing additionally the electric fields are considered. Implementing kinetics of occurring (bio-) chemical reactions in the numerical simulations of the temperature, flow and electric fields enables the evaluation of the process homogeneity and efficiency connected to different process parameters of the preservation techniques. Suggestions to achieve safe and high quality products are concluded out of the numerical results.

Vapor-dominated zones within hydrothermal systems: evolution and natural state

USGS Publications Warehouse

Ingebritsen, S.E.; Sorey, M.L.

1988-01-01

Three conceptual models illustrate the range of hydrothermal systems in which vapor-dominated conditions are found. The first model (model I) represents a system with an extensive near-vaporstatic vapor-dominated zone and limited liquid throughflow and is analogous to systems such as The Geysers, California. Models II and III represent systems with significant liquid throughflow and include steam-heated discharge features at higher elevations and high-chloride springs at lower elevations connected to and fed by a single circulation system at depth. In model II, as in model I, the vapor-dominated zone has a near-vaporstatic vertical pressure gradient and is generally underpressured with respect to local hydrostatic pressure. The vapor-dominated zone in model III is quite different, in that phase separation takes place at pressures close to local hydrostatic and the overall pressure gradient is near hydrostatic. -from Authors

A stable compound of helium and sodium at high pressure

DOE PAGES

Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.; ...

2017-02-06

Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na 2He, which has a fluorite-type structure and is stable at pressures >113 GPa. We show that the presence of He atoms causes strong electron localization and makes thismore » material insulating. This phase is an electride, with electron pairs localized in interstices, forming eight-centre two-electron bonds within empty Na 8 cubes. As a result, we also predict the existence of Na 2HeO with a similar structure at pressures above 15 GPa.« less

A stable compound of helium and sodium at high pressure

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

Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.

Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na 2He, which has a fluorite-type structure and is stable at pressures >113 GPa. We show that the presence of He atoms causes strong electron localization and makes thismore » material insulating. This phase is an electride, with electron pairs localized in interstices, forming eight-centre two-electron bonds within empty Na 8 cubes. We also predict the existence of Na 2HeO with a similar structure at pressures above 15 GPa.« less

A stable compound of helium and sodium at high pressure

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

Dong, Xiao; Oganov, Artem R.; Goncharov, Alexander F.

Helium is generally understood to be chemically inert and this is due to its extremely stable closed-shell electronic configuration, zero electron affinity and an unsurpassed ionization potential. It is not known to form thermodynamically stable compounds, except a few inclusion compounds. Here, using the ab initio evolutionary algorithm USPEX and subsequent high-pressure synthesis in a diamond anvil cell, we report the discovery of a thermodynamically stable compound of helium and sodium, Na 2He, which has a fluorite-type structure and is stable at pressures >113 GPa. We show that the presence of He atoms causes strong electron localization and makes thismore » material insulating. This phase is an electride, with electron pairs localized in interstices, forming eight-centre two-electron bonds within empty Na 8 cubes. As a result, we also predict the existence of Na 2HeO with a similar structure at pressures above 15 GPa.« less

Feasibility study of a pressure-fed engine for a water recoverable space shuttle booster. Volume 1: Executive summary

NASA Technical Reports Server (NTRS)

1972-01-01

An overview is presented of the results of the analyses conducted in support of the selected engine system for the pressure-fed booster stage. During initial phases of the project, a gimbaled, regeneratively cooled, fixed thrust engine having a coaxial pintle injector was selected as optimum for this configuration.

Nonextensivity in a Dark Maximum Entropy Landscape

NASA Astrophysics Data System (ADS)

Leubner, M. P.

2011-03-01

Nonextensive statistics along with network science, an emerging branch of graph theory, are increasingly recognized as potential interdisciplinary frameworks whenever systems are subject to long-range interactions and memory. Such settings are characterized by non-local interactions evolving in a non-Euclidean fractal/multi-fractal space-time making their behavior nonextensive. After summarizing the theoretical foundations from first principles, along with a discussion of entropy bifurcation and duality in nonextensive systems, we focus on selected significant astrophysical consequences. Those include the gravitational equilibria of dark matter (DM) and hot gas in clustered structures, the dark energy(DE) negative pressure landscape governed by the highest degree of mutual correlations and the hierarchy of discrete cosmic structure scales, available upon extremizing the generalized nonextensive link entropy in a homogeneous growing network.

A sensitivity model for energy consumption in buildings. Part 1: Effect of exterior environment

NASA Technical Reports Server (NTRS)

Lansing, F. L.

1981-01-01

A simple analytical model is developed for the simulation of seasonal heating and cooling loads of any class of buildings to complement available computerized techniques which make hourly, daily, and monthly calculations. An expression for the annual energy utilization index, which is a common measure of rating buildings having the same functional utilization, is derived to include about 30 parameters for both building interior and exterior environments. The sensitivity of a general class building to either controlled or uncontrolled weather parameters is examined. A hypothetical office type building, located at the Goldstone Space Communication Complex, Goldstone, California, is selected as an example for the numerical sensitivity evaluations. Several expressions of variations in local outside air temperature, pressure, solar radiation, and wind velocity are presented.

Gold nanoparticle plasmonics enhanced ultrafast laser-induced optoporation and stimulation of targeted cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Meunier, Michel; Bergeron, Éric; Lavoie-Cardinal, Flavie; Boutopoulos, Christos; Salesse, Charleen; Winnik, Françoise M.; De Koninck, Paul

2016-03-01

Gold nanoparticles (AuNPs) have found numerous applications in nanomedicine in view of their robustness, ease of functionalization and low toxicity. Upon irradiation of AuNPs by a pulsed ultrafast laser, various highly localized phenomena can be obtained including a temperature rise, pressure wave, charge injection and production of nanobubbles close to the cellular membrane [1]. These phenomena can be used to manipulate, optoperforate, transfect and stimulate targeted cells [2-5]. Irradiating at 800 nm in the optically biological transparent window, we demonstrated local optoporation and transfection of cells as well as local stimulation of neurons. Two recent examples will be given: (i) Laser-induced selective optoporation of cells: The technique can be used on various types of cells and a proof of principle will be given on human cancer cells in a co-culture using functionalized AuNPs [6]. (ii) Laser-induced stimulation of neurons and monitoring of the localized Ca2+ signaling: This all optical method uses a standard confocal microscope to trigger a transient increase in free Ca2+ in neurons covered by functionalized AuNPs as well as to measure these local variations optically with the Ca2+ sensor GCaMP6s [7]. The proposed techniques provide a new complement to light-dependent methods in neuroscience. REFERENCES (by our group): (1) Boulais, J. Photochem. Photobiol. C Photochem. Rev. 17, 26 (2013); (2) Baumgart, Biomaterials 33, 2345 (2012); (3) Boulais, NanoLett. 12, 4763 (2012); (4) Boutopoulos, J. Biophotonics (2015); (5) Boutopoulos, Nanoscale 7, 11758 (2015); (6) Bergeron, Biomaterials, submitted (2015); (7) Lavoie-Cardinal, Nature Commun. submitted (2015).