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

The role of non-thermal atmospheric pressure biocompatible plasma in the differentiation of osteoblastic precursor cells, MC3T3-E1.

PubMed

Han, Ihn; Choi, Eun Ha

2017-05-30

Non-thermal atmospheric pressure plasma is ionized matter, composed of highly reactive species that include positive ions, negative ions, free radicals, neutral atoms, and molecules. Recent reports have suggested that non-thermal biocompatible plasma (NBP) can selectively kill a variety of cancer cells, and promote stem cell differentiation. However as of yet, the regulation of proliferation and differentiation potential of NBP has been poorly understood.Here, we investigated the effects of NBP on the osteogenic differentiation of precursor cell lines of osteoblasts, MC3T3 E1 and SaOS-2. For in vitro osteogenic differentiation, precursor cell lines were treated with NBP, and cultured with osteogenic induction medium. After 10 days of treatment, the NBP was shown to be effective in osteogenic differentiation in MC3T3 E1 cells by von Kossa and Alizarin Red S staining assay. Real-time PCR was then performed to investigate the expression of osteogenic specific genes, Runx2, OCN, COL1, ALP and osterix in MC3T3 E1 cells after treatment with NBP for 4 days. Furthermore, analysis of the protein expression showed that NBP treatment significantly reduced PI3K/AKT signaling and MAPK family signaling. However, p38 controlled phosphorylation of transcription factor forkhead box O1 (FoxO1) that related to cell differentiation with increased phosphorylated p38. These results suggest that non-thermal atmospheric pressure plasma can induce osteogenic differentiation, and enhance bone formation.

Evaluation of Plastic Media Blasting Equipment

DTIC Science & Technology

1987-04-01

the differential pressure across the filter element or by a timer with a differential pressure switch override. The timer and the differential pressure ...automatic. The mechanism should be activated by the differential pressure across the filter element or by a timer with a differential pressure switch override...The timer and the differential pressure switch settings should be adjustable. The dust then falls to the bottom of the baghouse for

Evolution and ecology meet molecular genetics: adaptive phenotypic plasticity in two isolated Negev desert populations of Acacia raddiana at either end of a rainfall gradient

PubMed Central

Ward, David; Shrestha, Madan K.; Golan-Goldhirsh, Avi

2012-01-01

Background and Aims The ecological, evolutionary and genetic bases of population differentiation in a variable environment are often related to the selection pressures that plants experience. We compared differences in several growth- and defence-related traits in two isolated populations of Acacia raddiana trees from sites at either end of an extreme environmental gradient in the Negev desert. Methods We used random amplified polymorphic DNA (RAPD) to determine the molecular differences between populations. We grew plants under two levels of water, three levels of nutrients and three levels of herbivory to test for phenotypic plasticity and adaptive phenotypic plasticity. Key Results The RAPD analyses showed that these populations are highly genetically differentiated. Phenotypic plasticity in various morphological traits in A. raddiana was related to patterns of population genetic differentiation between the two study sites. Although we did not test for maternal effects in these long-lived trees, significant genotype × environment (G × E) interactions in some of these traits indicated that such plasticity may be adaptive. Conclusions The main selection pressure in this desert environment, perhaps unsurprisingly, is water. Increased water availability resulted in greater growth in the southern population, which normally receives far less rain than the northern population. Even under the conditions that we defined as low water and/or nutrients, the performance of the seedlings from the southern population was significantly better, perhaps reflecting selection for these traits. Consistent with previous studies of this genus, there was no evidence of trade-offs between physical and chemical defences and plant growth parameters in this study. Rather, there appeared to be positive correlations between plant size and defence parameters. The great variation in several traits in both populations may result in a diverse potential for responding to selection pressures in different environments. PMID:22039007

High-Fidelity Thermal Radiation Models and Measurements for High-Pressure Reacting Laminar and Turbulent Flows

DTIC Science & Technology

2013-06-26

flow code used ( OpenFOAM ) to include differential diffusion and cell-based stochastic RTE solvers. The models were validated by simulation of laminar...wavenumber selection is improved about by a factor of 10. (5) OpenFOAM Improvements for Laminar Flames A laminar-diffusion combustion solver, taking into...account the effects of differential diffusion, was developed within the open source CFD package OpenFOAM [18]. In addition, OpenFOAM was augmented to take

Fast-acting valve actuator

DOEpatents

Cho, Nakwon

1980-01-01

A fast-acting valve actuator utilizes a spring driven pneumatically loaded piston to drive a valve gate. Rapid exhaust of pressurized gas from the pneumatically loaded side of the piston facilitates an extremely rapid piston stroke. A flexible selector diaphragm opens and closes an exhaust port in response to pressure differentials created by energizing and de-energizing a solenoid which controls the pneumatic input to the actuator as well as selectively providing a venting action to one side of the selector diaphragm.

Spin-on bottom antireflective coating defect reduction by proper filter selection and process optimization

NASA Astrophysics Data System (ADS)

Brakensiek, Nickolas L.; Kidd, Brian; Mesawich, Michael; Stevens, Don, Jr.; Gotlinsky, Barry

2003-06-01

A design of experiment (DOE) was implemented to show the effects of various point of use filters on the coat process. The DOE takes into account the filter media, pore size, and pumping means, such as dispense pressure, time, and spin speed. The coating was executed on a TEL Mark 8 coat track, with an IDI M450 pump, and PALL 16 stack Falcon filters. A KLA 2112 set at 0.69 μm pixel size was used to scan the wafers to detect and identify the defects. The process found for DUV42P to maintain a low defect coating irrespective of the filter or pore size is a high start pressure, low end pressure, low dispense time, and high dispense speed. The IDI M450 pump has the capability to compensate for bubble type defects by venting the defects out of the filter before the defects are in the dispense line and the variable dispense rate allows the material in the dispense line to slow down at the end of dispense and not create microbubbles in the dispense line or tip. Also the differential pressure sensor will alarm if the pressure differential across the filter increases over a user-determined setpoint. The pleat design allows more surface area in the same footprint to reduce the differential pressure across the filter and transport defects to the vent tube. The correct low defect coating process will maximize the advantage of reducing filter pore size or changing the filter media.

Density-Independent Mortality and Increasing Plant Diversity Are Associated with Differentiation of Taraxacum officinale into r- and K-Strategists

PubMed Central

Lipowsky, Annett; Roscher, Christiane; Schumacher, Jens; Schmid, Bernhard

2012-01-01

Background Differential selection between clones of apomictic species may result in ecological differentiation without mutation and recombination, thus offering a simple system to study adaptation and life-history evolution in plants. Methodology/Principal Findings We caused density-independent mortality by weeding to colonizer populations of the largely apomictic Taraxacum officinale (Asteraceae) over a 5-year period in a grassland biodiversity experiment (Jena Experiment). We compared the offspring of colonizer populations with resident populations deliberately sown into similar communities. Plants raised from cuttings and seeds of colonizer and resident populations were grown under uniform conditions. Offspring from colonizer populations had higher reproductive output, which was in general agreement with predictions of r-selection theory. Offspring from resident populations had higher root and leaf biomass, fewer flower heads and higher individual seed mass as predicted under K-selection. Plants grown from cuttings and seeds differed to some degree in the strength, but not in the direction, of their response to the r- vs. K-selection regime. More diverse communities appeared to exert stronger K-selection on resident populations in plants grown from cuttings, while we did not find significant effects of increasing species richness on plants grown from seeds. Conclusions/Significance Differentiation into r- and K-strategists suggests that clones with characteristics of r-strategists were selected in regularly weeded plots through rapid colonization, while increasing plant diversity favoured the selection of clones with characteristics of K-strategists in resident populations. Our results show that different selection pressures may result in a rapid genetic differentiation within a largely apomictic species. Even under the assumption that colonizer and resident populations, respectively, happened to be r- vs. K-selected already at the start of the experiment, our results still indicate that the association of these strategies with the corresponding selection regimes was maintained during the 5-year experimental period. PMID:22253688

Density-independent mortality and increasing plant diversity are associated with differentiation of Taraxacum officinale into r- and K-strategists.

PubMed

Lipowsky, Annett; Roscher, Christiane; Schumacher, Jens; Schmid, Bernhard

2012-01-01

Differential selection between clones of apomictic species may result in ecological differentiation without mutation and recombination, thus offering a simple system to study adaptation and life-history evolution in plants. We caused density-independent mortality by weeding to colonizer populations of the largely apomictic Taraxacum officinale (Asteraceae) over a 5-year period in a grassland biodiversity experiment (Jena Experiment). We compared the offspring of colonizer populations with resident populations deliberately sown into similar communities. Plants raised from cuttings and seeds of colonizer and resident populations were grown under uniform conditions. Offspring from colonizer populations had higher reproductive output, which was in general agreement with predictions of r-selection theory. Offspring from resident populations had higher root and leaf biomass, fewer flower heads and higher individual seed mass as predicted under K-selection. Plants grown from cuttings and seeds differed to some degree in the strength, but not in the direction, of their response to the r- vs. K-selection regime. More diverse communities appeared to exert stronger K-selection on resident populations in plants grown from cuttings, while we did not find significant effects of increasing species richness on plants grown from seeds. Differentiation into r- and K-strategists suggests that clones with characteristics of r-strategists were selected in regularly weeded plots through rapid colonization, while increasing plant diversity favoured the selection of clones with characteristics of K-strategists in resident populations. Our results show that different selection pressures may result in a rapid genetic differentiation within a largely apomictic species. Even under the assumption that colonizer and resident populations, respectively, happened to be r- vs. K-selected already at the start of the experiment, our results still indicate that the association of these strategies with the corresponding selection regimes was maintained during the 5-year experimental period.

PRESSURE SENSING DEVICE

DOEpatents

Pope, K.E.

1959-12-15

This device is primarily useful as a switch which is selectively operable to actuate in response to either absolute or differential predetermined pressures. The device generally comprises a pressure-tight housing divided by a movable impermeable diaphragm into two chambers, a reference pressure chamber and a bulb chamber containing the switching means and otherwise filled with an incompressible non-conducting fluid. The switch means comprises a normally collapsed bulb having an electrically conductive outer surface and a vent tube leading to the housing exterior. The normally collapsed bulb is disposed such that upon its inflation, respensive to air inflow from the vent, two contacts fixed within the bulb chamber are adapted to be electrically shorted by the conducting outer surface of the bulb.

Apparatus and method for polymer synthesis using arrays

DOEpatents

Brennan, Thomas M.

1995-01-01

A polymer synthesis apparatus (20) for building a polymer chain including a head assembly (21) having an array of nozzles (22) with each nozzle coupled to a reservoir (23) of liquid reagent (24) , and a base assembly (25) having an array of reaction wells (26). A transport mechanism (27) aligns the reaction wells (26) and selected nozzles (22) for deposition of the liquid reagent (24) into selected reaction wells (26). A sliding seal (30) is positioned between the head assembly (21) and the base assembly (25) to form a common chamber (31) enclosing both the reaction well (26) and the nozzles (22) therein. A gas inlet (70) into the common chamber (31), upstream from the nozzles (22), and a gas outlet (71) out of the common chamber (31) , downstream from the nozzles (22) , sweeps the common chamber ( 31 ) of toxic fumes emitted by the reagents. Each reaction well (26) includes an orifice (74) extending into the well (26) which is of a size and dimension to form a capillary liquid seal to retain the reagent solution (76) in the well (26) for polymer chain growth therein. A pressure regulating device (82) is provided for controlling a pressure differential, between a first gas pressure exerted on the reaction well (26) and a second gas pressure exerted on an exit (80) of the orifice, such that upon the pressure differential exceeding a predetermined amount, the reagent solution (76) is expelled from the well (26) through the orifice (74). A method of synthesis of a polymer chain in a synthesis apparatus (20) is also included.

Apparatus and method for polymer synthesis using arrays

DOEpatents

Brennan, Thomas M.

1996-01-01

A polymer synthesis apparatus (20) for building a polymer chain including a head assembly (21) having an array of nozzles (22) with each nozzle coupled to a reservoir (23) of liquid reagent (24), and a base assembly (25) having an array of reaction wells (26). A transport mechanism (27) aligns the reaction wells (26) and selected nozzles (22) for deposition of the liquid reagent (24) into selected reaction wells (26). A sliding seal (30) is positioned between the head assembly (21) and the base assembly (25) to form a common chamber (31) enclosing both the reaction well (26) and the nozzles (22) therein. A gas inlet (70) into the common chamber (31), upstream from the nozzles (22), and a gas outlet (71) out of the common chamber (31), downstream from the nozzles (22), sweeps the common chamber (31) of toxic fumes emitted by the reagents. Each reaction well ( 26) includes an orifice (74) extending into the well (26) which is of a size and dimension to form a capillary liquid seal to retain the reagent solution (76) in the well (26) for polymer chain growth therein. A pressure regulating device (82 ) is provided for controlling a pressure differential, between a first gas pressure exerted on the reaction well (26) and a second gas pressure exerted on an exit (80) of the orifice, such that upon the pressure differential exceeding a predetermined amount, the reagent solution (76) is expelled from the well (26) through the orifice (74). A method of synthesis of a polymer chain in a synthesis apparatus (20) is also included.

Genomics of Parallel Ecological Speciation in Lake Victoria Cichlids.

PubMed

Meier, Joana Isabel; Marques, David Alexander; Wagner, Catherine Elise; Excoffier, Laurent; Seehausen, Ole

2018-06-01

The genetic basis of parallel evolution of similar species is of great interest in evolutionary biology. In the adaptive radiation of Lake Victoria cichlid fishes, sister species with either blue or red-back male nuptial coloration have evolved repeatedly, often associated with shallower and deeper water, respectively. One such case is blue and red-backed Pundamilia species, for which we recently showed that a young species pair may have evolved through "hybrid parallel speciation". Coalescent simulations suggested that the older species P. pundamilia (blue) and P. nyererei (red-back) admixed in the Mwanza Gulf and that new "nyererei-like" and "pundamilia-like" species evolved from the admixed population. Here, we use genome scans to study the genomic architecture of differentiation, and assess the influence of hybridization on the evolution of the younger species pair. For each of the two species pairs, we find over 300 genomic regions, widespread across the genome, which are highly differentiated. A subset of the most strongly differentiated regions of the older pair are also differentiated in the younger pair. These shared differentiated regions often show parallel allele frequency differences, consistent with the hypothesis that admixture-derived alleles were targeted by divergent selection in the hybrid population. However, two-thirds of the genomic regions that are highly differentiated between the younger species are not highly differentiated between the older species, suggesting independent evolutionary responses to selection pressures. Our analyses reveal how divergent selection on admixture-derived genetic variation can facilitate new speciation events.

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.

Generational distribution of a Candida glabrata population: Resilient old cells prevail, while younger cells dominate in the vulnerable host.

PubMed

Bouklas, Tejas; Alonso-Crisóstomo, Luz; Székely, Tamás; Diago-Navarro, Elizabeth; Orner, Erika P; Smith, Kalie; Munshi, Mansa A; Del Poeta, Maurizio; Balázsi, Gábor; Fries, Bettina C

2017-05-01

Similar to other yeasts, the human pathogen Candida glabrata ages when it undergoes asymmetric, finite cell divisions, which determines its replicative lifespan. We sought to investigate if and how aging changes resilience of C. glabrata populations in the host environment. Our data demonstrate that old C. glabrata are more resistant to hydrogen peroxide and neutrophil killing, whereas young cells adhere better to epithelial cell layers. Consequently, virulence of old compared to younger C. glabrata cells is enhanced in the Galleria mellonella infection model. Electron microscopy images of old C. glabrata cells indicate a marked increase in cell wall thickness. Comparison of transcriptomes of old and young C. glabrata cells reveals differential regulation of ergosterol and Hog pathway associated genes as well as adhesion proteins, and suggests that aging is accompanied by remodeling of the fungal cell wall. Biochemical analysis supports this conclusion as older cells exhibit a qualitatively different lipid composition, leading to the observed increased emergence of fluconazole resistance when grown in the presence of fluconazole selection pressure. Older C. glabrata cells accumulate during murine and human infection, which is statistically unlikely without very strong selection. Therefore, we tested the hypothesis that neutrophils constitute the predominant selection pressure in vivo. When we altered experimentally the selection pressure by antibody-mediated removal of neutrophils, we observed a significantly younger pathogen population in mice. Mathematical modeling confirmed that differential selection of older cells is sufficient to cause the observed demographic shift in the fungal population. Hence our data support the concept that pathogenesis is affected by the generational age distribution of the infecting C. glabrata population in a host. We conclude that replicative aging constitutes an emerging trait, which is selected by the host and may even play an unanticipated role in the transition from a commensal to a pathogen state.

Transcriptome sequencing of Eucalyptus camaldulensis seedlings subjected to water stress reveals functional single nucleotide polymorphisms and genes under selection

PubMed Central

2012-01-01

Background Water stress limits plant survival and production in many parts of the world. Identification of genes and alleles responding to water stress conditions is important in breeding plants better adapted to drought. Currently there are no studies examining the transcriptome wide gene and allelic expression patterns under water stress conditions. We used RNA sequencing (RNA-seq) to identify the candidate genes and alleles and to explore the evolutionary signatures of selection. Results We studied the effect of water stress on gene expression in Eucalyptus camaldulensis seedlings derived from three natural populations. We used reference-guided transcriptome mapping to study gene expression. Several genes showed differential expression between control and stress conditions. Gene ontology (GO) enrichment tests revealed up-regulation of 140 stress-related gene categories and down-regulation of 35 metabolic and cell wall organisation gene categories. More than 190,000 single nucleotide polymorphisms (SNPs) were detected and 2737 of these showed differential allelic expression. Allelic expression of 52% of these variants was correlated with differential gene expression. Signatures of selection patterns were studied by estimating the proportion of nonsynonymous to synonymous substitution rates (Ka/Ks). The average Ka/Ks ratio among the 13,719 genes was 0.39 indicating that most of the genes are under purifying selection. Among the positively selected genes (Ka/Ks > 1.5) apoptosis and cell death categories were enriched. Of the 287 positively selected genes, ninety genes showed differential expression and 27 SNPs from 17 positively selected genes showed differential allelic expression between treatments. Conclusions Correlation of allelic expression of several SNPs with total gene expression indicates that these variants may be the cis-acting variants or in linkage disequilibrium with such variants. Enrichment of apoptosis and cell death gene categories among the positively selected genes reveals the past selection pressures experienced by the populations used in this study. PMID:22853646

Re-electrospraying splash-landed proteins and nanoparticles.

PubMed

Benner, W Henry; Lewis, Gregory S; Hering, Susanne V; Selgelke, Brent; Corzett, Michelle; Evans, James E; Lightstone, Felice C

2012-03-06

FITC-albumin, Lsr-F, or fluorescent polystyrene latex particles were electrosprayed from aqueous buffer and subjected to dispersion by differential electrical mobility at atmospheric pressure. A resulting narrow size cut of singly charged molecular ions or particles was passed through a condensation growth tube collector to create a flow stream of small water droplets, each carrying a single ion or particle. The droplets were splash landed (impacted) onto a solid or liquid temperature controlled surface. Small pools of droplets containing size-selected particles, FITC-albumin, or Lsr-F were recovered, re-electrosprayed, and, when analyzed a second time by differential electrical mobility, showed increased homogeneity. Transmission electron microscopy (TEM) analysis of the size-selected Lsr-F sample corroborated the mobility observation.

VACUUM SEALING MEANS FOR LOW VACUUM PRESSURES

DOEpatents

Milleron, N.

1962-06-12

S>A vacuum seal is designed in which the surface tension of a thin layer of liquid metal of low vapor pressure cooperates with adjacent surfaces to preclude passages of gases across pressure differentials as low as 10/sup -8/ mm Hg. Mating contiguous surfaces composed of copper, brass, stainless steel, nickel, molybdenum, tungsten, tantalum, glass, quartz, and/or synthetic mica are disposed to provide a maximum tolerance, D, expressed by 2 gamma /P/sub 1/, where gamma is the coefflcient of the surface tension of the metal sealant selected in dynes/cm/sub 2/. Means for heating the surfaces remotely is provided where temperatures drop below about 250 deg C. A sealant consisting of an alloy of gallium, indium, and tin, among other combinations tabulated, is disposed therebetween after treating the surfaces to improve wettability, as by ultrasonic vibrations, the surfaces and sealants being selected according to the anticipated experimental conditions of use. (AEC)

Changes in sparkling wine aroma during the second fermentation under CO2 pressure in sealed bottle.

PubMed

Martínez-García, Rafael; García-Martínez, Teresa; Puig-Pujol, Anna; Mauricio, Juan Carlos; Moreno, Juan

2017-12-15

High quality sparkling wine made by the traditional method requires a second alcoholic fermentation of a base wine in sealed bottles, followed by an aging time in contact with yeast lees. The CO 2 overpressure released during this second fermentation has an important effect on the yeast metabolism and therefore on the wine aroma composition. This study focuses on the changes in chemical composition and 43 aroma compounds released by yeast during this fermentation carried out under two pressure conditions. The data were subjected to statistical analysis allowing differentiating between the base wine and the wine samples taken in the middle and at the end of fermentation. The differentiation among wines obtained to the end of fermentation with or without CO 2 pressure is only achieved by a principal component analysis of 15 selected minor compounds (mainly ethyl dodecanoate, ethyl tetradecanoate, hexyl acetate, ethyl butanoate and ethyl isobutanoate). Copyright © 2017 Elsevier Ltd. All rights reserved.

Analysis of differential selective forces acting on the coat protein (P3) of the plant virus family Luteoviridae.

PubMed

Torres, Marina W; Corrêa, Régis L; Schrago, Carlos G

2005-12-30

The coat protein (CP) of the family Luteoviridae is directly associated with the success of infection. It participates in various steps of the virus life cycle, such as virion assembly, stability, systemic infection, and transmission. Despite its importance, extensive studies on the molecular evolution of this protein are lacking. In the present study, we investigate the action of differential selective forces on the CP coding region using maximum likelihood methods. We found that the protein is subjected to heterogeneous selective pressures and some sites may be evolving near neutrality. Based on the proposed 3-D model of the CP S-domain, we showed that nearly neutral sites are predominantly located in the region of the protein that faces the interior of the capsid, in close contact with the viral RNA, while highly conserved sites are mainly part of beta-strands, in the protein's major framework.

Differential pressure sensing system for airfoils usable in turbine engines

DOEpatents

Yang, Wen-Ching; Stampahar, Maria E.

2005-09-13

A detection system for identifying airfoils having a cooling systems with orifices that are plugged with contaminants or with showerheads having a portion burned off. The detection system measures pressures at different locations and calculates or measures a differential pressure. The differential pressure may be compared with a known benchmark value to determine whether the differential pressure has changed. Changes in the differential pressure may indicate that one or more of the orifices in a cooling system of an airfoil are plugged or that portions of, or all of, a showerhead has burned off.

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.

Nonneutral GC3 and retroelement codon mimicry in Phytophthora.

PubMed

Jiang, Rays H Y; Govers, Francine

2006-10-01

Phytophthora is a genus entirely comprised of destructive plant pathogens. It belongs to the Stramenopila, a unique branch of eukaryotes, phylogenetically distinct from plants, animals, or fungi. Phytophthora genes show a strong preference for usage of codons ending with G or C (high GC3). The presence of high GC3 in genes can be utilized to differentiate coding regions from noncoding regions in the genome. We found that both selective pressure and mutation bias drive codon bias in Phytophthora. Indicative for selection pressure is the higher GC3 value of highly expressed genes in different Phytophthora species. Lineage specific GC increase of noncoding regions is reminiscent of whole-genome mutation bias, whereas the elevated Phytophthora GC3 is primarily a result of translation efficiency-driven selection. Heterogeneous retrotransposons exist in Phytophthora genomes and many of them vary in their GC content. Interestingly, the most widespread groups of retroelements in Phytophthora show high GC3 and a codon bias that is similar to host genes. Apparently, selection pressure has been exerted on the retroelement's codon usage, and such mimicry of host codon bias might be beneficial for the propagation of retrotransposons.

Catch a tiger snake by its tail: Differential toxicity, co-factor dependence and antivenom efficacy in a procoagulant clade of Australian venomous snakes.

PubMed

Lister, Callum; Arbuckle, Kevin; Jackson, Timothy N W; Debono, Jordan; Zdenek, Christina N; Dashevsky, Daniel; Dunstan, Nathan; Allen, Luke; Hay, Chris; Bush, Brian; Gillett, Amber; Fry, Bryan G

2017-11-01

A paradigm of venom research is adaptive evolution of toxins as part of a predator-prey chemical arms race. This study examined differential co-factor dependence, variations relative to dietary preference, and the impact upon relative neutralisation by antivenom of the procoagulant toxins in the venoms of a clade of Australian snakes. All genera were characterised by venoms rich in factor Xa which act upon endogenous prothrombin. Examination of toxin sequences revealed an extraordinary level of conservation, which indicates that adaptive evolution is not a feature of this toxin type. Consistent with this, the venoms did not display differences on the plasma of different taxa. Examination of the prothrombin target revealed endogenous blood proteins are under extreme negative selection pressure for diversification, this in turn puts a strong negative selection pressure upon the toxins as sequence diversification could result in a drift away from the target. Thus this study reveals that adaptive evolution is not a consistent feature in toxin evolution in cases where the target is under negative selection pressure for diversification. Consistent with this high level of toxin conservation, the antivenom showed extremely high-levels of cross-reactivity. There was however a strong statistical correlation between relative degree of phospholipid-dependence and clotting time, with the least dependent venoms producing faster clotting times than the other venoms even in the presence of phospholipid. The results of this study are not only of interest to evolutionary and ecological disciplines, but also have implications for clinical toxinology. Copyright © 2017 Elsevier Inc. All rights reserved.

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...

Hydraulic High Pressure Valve Controller Using the In-Situ Pressure Difference

NASA Technical Reports Server (NTRS)

Badescu, Mircea (Inventor); Bar-Cohen, Yoseph (Inventor); Hall, Jeffery L. (Inventor); Sherrit, Stewart (Inventor); Bao, Xiaoqi (Inventor)

2016-01-01

A hydraulic valve controller that uses an existing pressure differential as some or all of the power source for valve operation. In a high pressure environment, such as downhole in an oil or gas well, the pressure differential between the inside of a pipe and the outside of the pipe may be adequately large to drive a linear slide valve. The valve is operated hydraulically by a piston in a bore. When a higher pressure is applied to one end of the bore and a lower pressure to the other end, the piston moves in response to the pressure differential and drives a valve attached to it. If the pressure differential is too small to drive the piston at a sufficiently high speed, a pump is provided to generate a larger pressure differential to be applied. The apparatus is conveniently constructed using multiport valves, which can be rotary valves.

Differential mobility spectroscopy for chemical agent detection

NASA Astrophysics Data System (ADS)

Griffin, M. Todd

2006-05-01

General Dynamics ATP (GDATP) and Sionex Corporation (Sionex) are carrying out a cooperative development for a handheld chemical agent detector, being called JUNO TM, which will have lower false positives, higher sensitivity, and improved interference rejection compared with presently available detectors. This enhanced performance is made possible by the use of a new principle of ion separation called Differential Mobility Spectrometry (DMS). The enhanced selectivity is provided by the field tunable nature of the Sionex differential mobility technology (microDMxTM) which forms the analytical heart of the JUNO system and enables fingerprinting of molecules by characterization of the ionized molecular behavior under multiple electric field conditions. This enhanced selectivity is valuable in addressing not only the traditional list of chemical warfare agents (CWA) but also the substantial list of Toxic Industrial Compounds (TICs) and Toxic Industrial Materials (TIMs) which may be released in warfare or terrorist situations. Experimental results showing the ability of the microDMx to reject interferences, detect and resolve live agents are presented. An additional breakthrough in the technology was realized by operating the device at a reduced pressure of around 0.5 atmospheres. This reduced pressure operation resulted in roughly doubling the spectrometers resolution over what has previously been reported [1]. Advances have also been made in power consumption and packaging leading to a device suitable for portable, handheld, applications. Experimental results illustrating the performance of the microDMx technology employed in JUNO are highlighted.

[Characteristics of auto-CPAP devices during the simulation of sleep-related breathing flow patterns].

PubMed

Rühle, K H; Karweina, D; Domanski, U; Nilius, G

2009-07-01

The function of automatic CPAP devices is difficult to investigate using clinical examinations due to the high variability of breathing disorders. With a flow generator, however, identical breathing patterns can be reproduced so that comparative studies on the behaviour of pressure of APAP devices are possible. Because the algorithms of APAP devices based on the experience of users can be modified without much effort, also previously investigated devices should regularly be reviewed with regard to programme changes. Had changes occurred in the algorithms of 3 selected devices--compared to the previously published benchmark studies? Do the current versions of these investigated devices differentiate between open and closed apnoeas? With a self-developed respiratory pump, sleep-related breathing patterns and, with the help of a computerised valve, resistances of the upper respiratory tract were simulated. Three different auto-CPAP devices were subjected to a bench test with and without feedback (open/closed loop). Open loop: the 3 devices showed marked differences in the rate of pressure rise but did not differ from the earlier published results. From an initial pressure of 4 mbar the pressure increased to 10 mbar after a different number of apnoeas (1-6 repetitive apnoeas). Only one device differentiated between closed and open apnoeas. Closed loop: due to the pressure increase, the flow generator simulated reduced obstruction of the upper airways (apnoeas changed to hypopnoeas, hypopnoeas changed to flattening) but different patterns of pressure regulation could still be observed. By applying bench-testing, the algorithms of auto-CPAP devices can regularly be reviewed to detect changes in the software. The differentiation between open and closed apnoeas should be improved in several APAP devices.

Opportunity for natural selection among five population groups of Manipur, North East India.

PubMed

Asghar, M; Meitei, S Y; Luxmi, Y; Achoubi, N; Meitei, K S; Murry, B; Sachdeva, M P; Saraswathy, K N

2014-01-01

Opportunity for natural selection among five population groups of Manipur in comparison with other North East Indian population has been studied. Crow's index as well as Johnston and Kensinger's index for natural selection were calculated based on differential fertility and mortality. The mortality component was found to be lower compared to fertility component in all the populations which may attribute to comparatively improved and easily accessible health care facilities. However, different selection pressures, artificial and natural, seem to be influencing the selection intensity through induced abortion and spontaneous abortion among the two non-tribal migrant groups: Bamon and Muslims, respectively. This study highlights the probable interaction of artificial and natural selection in determining the evolutionary fate of any population group.

High accuracy differential pressure measurements using fluid-filled catheters - A feasibility study in compliant tubes.

PubMed

Rotman, Oren Moshe; Weiss, Dar; Zaretsky, Uri; Shitzer, Avraham; Einav, Shmuel

2015-09-18

High accuracy differential pressure measurements are required in various biomedical and medical applications, such as in fluid-dynamic test systems, or in the cath-lab. Differential pressure measurements using fluid-filled catheters are relatively inexpensive, yet may be subjected to common mode pressure errors (CMP), which can significantly reduce the measurement accuracy. Recently, a novel correction method for high accuracy differential pressure measurements was presented, and was shown to effectively remove CMP distortions from measurements acquired in rigid tubes. The purpose of the present study was to test the feasibility of this correction method inside compliant tubes, which effectively simulate arteries. Two tubes with varying compliance were tested under dynamic flow and pressure conditions to cover the physiological range of radial distensibility in coronary arteries. A third, compliant model, with a 70% stenosis severity was additionally tested. Differential pressure measurements were acquired over a 3 cm tube length using a fluid-filled double-lumen catheter, and were corrected using the proposed CMP correction method. Validation of the corrected differential pressure signals was performed by comparison to differential pressure recordings taken via a direct connection to the compliant tubes, and by comparison to predicted differential pressure readings of matching fluid-structure interaction (FSI) computational simulations. The results show excellent agreement between the experimentally acquired and computationally determined differential pressure signals. This validates the application of the CMP correction method in compliant tubes of the physiological range for up to intermediate size stenosis severity of 70%. Copyright © 2015 Elsevier Ltd. All rights reserved.

STE/ICE (Simplified Test Equipment/Internal Combustion Engines) Design Guide for Vehicle Diagnostic Connector Assemblies

DTIC Science & Technology

1982-08-01

19 3.2 Diesel Engine Speed Transducer 20 3.3 Pressure Transducer 20 3.4 Temperature Transducer 22 3.5 Differential Pressure Switch 22 3.6 Differential... Pressure Switch , Multi-Point 22 3.7 Current Measurement Transducer 23 - 3.8 Electrolyte Level Probes 23 3.9 Diagnostic Connector 24 3.10 Harness...12258933 Differential Pressure Switch - Multi-point 12258934 K -. Differential Pressure Switch 12258938 Electrolyte Level Sensor 12258935 Shunt 1000

Effect of pressure on the selectivity of polymeric C18 and C30 stationary phases in reversed-phase liquid chromatography. Increased separation of isomeric fatty acid methyl esters, triacylglycerols, and tocopherols at high pressure.

PubMed

Okusa, Kensuke; Iwasaki, Yuki; Kuroda, Ikuma; Miwa, Shohei; Ohira, Masayoshi; Nagai, Toshiharu; Mizobe, Hoyo; Gotoh, Naohiro; Ikegami, Tohru; McCalley, David V; Tanaka, Nobuo

2014-04-25

A high-density, polymeric C18 stationary phase (Inertsil ODS-P) or a polymeric C30 phase (Inertsil C30) provided improved resolution of the isomeric fatty acids (FAs), FA methyl esters (FAMEs), triacylglycerols (TAGs), and tocopherols with an increase in pressure of 20-70MPa in reversed-phase HPLC. With respect to isomeric C18 FAMEs with one cis-double bond, ODS-P phase was effective for recognizing the position of a double bond among petroselinic (methyl 6Z-octadecenoate), oleic (methyl 9Z-octadecenoate), and cis-vaccenic (methyl 11Z-octadecenoate), especially at high pressure, but the differentiation between oleic and cis-vaccenic was not achieved by C30 phase regardless of the pressure. A monomeric C18 phase (InertSustain C18) was not effective for recognizing the position of the double bond in monounsaturated FAME, while the separation of cis- and trans-isomers was achieved by any of the stationary phases. The ODS-P and C30 phases provided increased separation for TAGs and β- and γ-tocopherols at high pressure. The transfer of FA, FAME, or TAG molecules from the mobile phase to the ODS-P stationary phase was accompanied by large volume reduction (-30∼-90mL/mol) resulting in a large increase in retention (up to 100% for an increase of 50MPa) and improved isomer separation at high pressure. For some isomer pairs, the ODS-P and C30 provided the opposite elution order, and in each case higher pressure improved the separation. The two stationary phases showed selectivity for the isomers having rigid structures, but only the ODS-P was effective for differentiating the position of a double bond in monounsaturated FAMEs. The results indicate that the improved isomer separation was provided by the increased dispersion interactions between the solute and the binding site of the stationary phase at high pressure. Copyright © 2014 Elsevier B.V. All rights reserved.

Geometric morphometrics reveals sex-differential shape allometry in a spider.

PubMed

Fernández-Montraveta, Carmen; Marugán-Lobón, Jesús

2017-01-01

Common scientific wisdom assumes that spider sexual dimorphism (SD) mostly results from sexual selection operating on males. However, testing predictions from this hypothesis, particularly male size hyperallometry, has been restricted by methodological constraints. Here, using geometric morphometrics (GMM) we studied for the first time sex-differential shape allometry in a spider ( Donacosa merlini , Araneae: Lycosidae) known to exhibit the reverse pattern (i.e., male-biased) of spider sexual size dimorphism. GMM reveals previously undetected sex-differential shape allometry and sex-related shape differences that are size independent (i.e., associated to the y-intercept, and not to size scaling). Sexual shape dimorphism affects both the relative carapace-to-opisthosoma size and the carapace geometry, arguably resulting from sex differences in both reproductive roles (female egg load and male competition) and life styles (wandering males and burrowing females). Our results demonstrate that body portions may vary modularly in response to different selection pressures, giving rise to sex differences in shape, which reconciles previously considered mutually exclusive interpretations about the origins of spider SD.

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species.

PubMed

Zhong, Zhenhui; Norvienyeku, Justice; Chen, Meilian; Bao, Jiandong; Lin, Lianyu; Chen, Liqiong; Lin, Yahong; Wu, Xiaoxian; Cai, Zena; Zhang, Qi; Lin, Xiaoye; Hong, Yonghe; Huang, Jun; Xu, Linghong; Zhang, Honghong; Chen, Long; Tang, Wei; Zheng, Huakun; Chen, Xiaofeng; Wang, Yanli; Lian, Bi; Zhang, Liangsheng; Tang, Haibao; Lu, Guodong; Ebbole, Daniel J; Wang, Baohua; Wang, Zonghua

2016-05-06

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants.

Directional Selection from Host Plants Is a Major Force Driving Host Specificity in Magnaporthe Species

PubMed Central

Zhong, Zhenhui; Norvienyeku, Justice; Chen, Meilian; Bao, Jiandong; Lin, Lianyu; Chen, Liqiong; Lin, Yahong; Wu, Xiaoxian; Cai, Zena; Zhang, Qi; Lin, Xiaoye; Hong, Yonghe; Huang, Jun; Xu, Linghong; Zhang, Honghong; Chen, Long; Tang, Wei; Zheng, Huakun; Chen, Xiaofeng; Wang, Yanli; Lian, Bi; Zhang, Liangsheng; Tang, Haibao; Lu, Guodong; Ebbole, Daniel J.; Wang, Baohua; Wang, Zonghua

2016-01-01

One major threat to global food security that requires immediate attention, is the increasing incidence of host shift and host expansion in growing number of pathogenic fungi and emergence of new pathogens. The threat is more alarming because, yield quality and quantity improvement efforts are encouraging the cultivation of uniform plants with low genetic diversity that are increasingly susceptible to emerging pathogens. However, the influence of host genome differentiation on pathogen genome differentiation and its contribution to emergence and adaptability is still obscure. Here, we compared genome sequence of 6 isolates of Magnaporthe species obtained from three different host plants. We demonstrated the evolutionary relationship between Magnaporthe species and the influence of host differentiation on pathogens. Phylogenetic analysis showed that evolution of pathogen directly corresponds with host divergence, suggesting that host-pathogen interaction has led to co-evolution. Furthermore, we identified an asymmetric selection pressure on Magnaporthe species. Oryza sativa-infecting isolates showed higher directional selection from host and subsequently tends to lower the genetic diversity in its genome. We concluded that, frequent gene loss or gain, new transposon acquisition and sequence divergence are host adaptability mechanisms for Magnaporthe species, and this coevolution processes is greatly driven by directional selection from host plants. PMID:27151494

Quantitative and qualitative shifts in defensive metabolites define chemical defense investment during leaf development in Inga, a genus of tropical trees.

PubMed

Wiggins, Natasha L; Forrister, Dale L; Endara, María-José; Coley, Phyllis D; Kursar, Thomas A

2016-01-01

Selective pressures imposed by herbivores are often positively correlated with investments that plants make in defense. Research based on the framework of an evolutionary arms race has improved our understanding of why the amount and types of defenses differ between plant species. However, plant species are exposed to different selective pressures during the life of a leaf, such that expanding leaves suffer more damage from herbivores and pathogens than mature leaves. We hypothesize that this differential selective pressure may result in contrasting quantitative and qualitative defense investment in plants exposed to natural selective pressures in the field. To characterize shifts in chemical defenses, we chose six species of Inga, a speciose Neotropical tree genus. Focal species represent diverse chemical, morphological, and developmental defense traits and were collected from a single site in the Amazonian rainforest. Chemical defenses were measured gravimetrically and by characterizing the metabolome of expanding and mature leaves. Quantitative investment in phenolics plus saponins, the major classes of chemical defenses identified in Inga, was greater for expanding than mature leaves (46% and 24% of dry weight, respectively). This supports the theory that, because expanding leaves are under greater selective pressure from herbivores, they rely more upon chemical defense as an antiherbivore strategy than do mature leaves. Qualitatively, mature and expanding leaves were distinct and mature leaves contained more total and unique metabolites. Intraspecific variation was greater for mature leaves than expanding leaves, suggesting that leaf development is canalized. This study provides a snapshot of chemical defense investment in a speciose genus of tropical trees during the short, few-week period of leaf development. Exploring the metabolome through quantitative and qualitative profiling enables a more comprehensive examination of foliar chemical defense investment.

Differential Intracochlear Sound Pressure Measurements in Normal Human Temporal Bones

NASA Astrophysics Data System (ADS)

Nakajima, Hideko Heidi; Dong, Wei; Olson, Elizabeth S.; Merchant, Saumil N.; Ravicz, Michael E.; Rosowski, John J.

2009-02-01

We present the first simultaneous sound pressure measurements in scala vestibuli and scala tympani of the cochlea in human cadaveric temporal bones. Micro-scale fiberoptic pressure sensors enabled the study of differential sound pressure at the cochlear base. This differential pressure is the input to the cochlear partition, driving cochlear waves and auditory transduction. Results showed that: pressure of scala vestibuli was much greater than scala tympani except at low and high frequencies where scala tympani pressure affects the input to the cochlea; the differential pressure proved to be an excellent measure of normal ossicular transduction of sound (shown to decrease 30-50 dB with ossicular disarticulation, whereas the individual scala pressures were significantly affected by non-ossicular conduction of sound at high frequencies); the middle-ear gain and differential pressure were generally bandpass in frequency dependence; and the middle-ear delay in the human was over twice that of the gerbil. Concurrent stapes velocity measurements allowed determination of the differential impedance across the partition and round-window impedance. The differential impedance was generally resistive, while the round-window impedance was consistent with a compliance in conjunction with distributed inertia and damping. Our techniques can be used to study inner-ear conductive pathologies (e.g., semicircular dehiscence), as well as non-ossicular cochlear stimulation (e.g., round-window stimulation) - situations that cannot be completely quantified by measurements of stapes velocity or scala-vestibuli pressure by themselves.

Implanted Blood-Pressure-Measuring Device

NASA Technical Reports Server (NTRS)

Fischell, Robert E.

1988-01-01

Arterial pressure compared with ambient bodily-fluid pressure. Implanted apparatus, capable of measuring blood pressure of patient, includes differential-pressure transducer connected to pressure sensor positioned in major artery. Electrical signal is function of differential pressure between blood-pressure sensor and reference-pressure sensor transmitted through skin of patient to recorder or indicator.

Vapor Pressure Data and Analysis for Selected Organophosphorus Compounds: DIBMP, DCMP, IMMP, IMPA, EMPA, and MPFA

DTIC Science & Technology

2017-04-01

Methodology, Statistics, and Applications; CRDEC-TR-386; U.S. Army Chemical Research, Development and Engineering Center: Aberdeen Proving Ground...Approved for public release; distribution unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT: Recent work from our laboratory has focused on chemical ...vaporization Volatility Differential scanning calorimetry (DSC) Vapor saturation Boiling point Diisobutyl methylphosphonate (DIBMP), Chemical Abstracts

Phenotypic selection to increase floral scent emission, but not flower size or colour in bee-pollinated Penstemon digitalis.

PubMed

Parachnowitsch, Amy L; Raguso, Robert A; Kessler, André

2012-08-01

Fragrance is a putatively important character in the evolution of flowering plants, but natural selection on scent is rarely studied and thus poorly understood. We characterized floral scent composition and emission in a common garden of Penstemon digitalis from three nearby source populations. We measured phenotypic selection on scent as well as floral traits more frequently examined, such as floral phenology, display size, corolla pigment, and inflorescence height. Scent differed among populations in a common garden, underscoring the potential for scent to be shaped by differential selection pressures. Phenotypic selection on flower number and display size was strong. However, selection favoured scent rather than flower size or colour, suggesting that smelling stronger benefits reproductive success in P. digitalis. Linalool was a direct target of selection and its high frequency in floral-scent bouquets suggests that further studies of both pollinator- and antagonist-mediated selection on this compound would further our understanding of scent evolution. Our results indicate that chemical dimensions of floral display are just as likely as other components to experience selective pressure in a nonspecialized flowering herb. Therefore, studies that integrate visual and chemical floral traits should better reflect the true nature of floral evolutionary ecology. © 2012 The Authors. New Phytologist © 2012 New Phytologist Trust.

A program to evaluate a control system based on feedback of aerodynamic pressure differentials

NASA Technical Reports Server (NTRS)

Levy, D. W.; Finn, P.; Roskam, J.

1981-01-01

The use of aerodynamic pressure differentials to position a control surface is evaluated. The system is a differential pressure command loop, analogous to a position command loop, where the surface is commanded to move until a desired differential pressure across the surface is achieved. This type of control is more direct and accurate because it is the differential pressure which causes the control forces and moments. A frequency response test was performed in a low speed wind tunnel to measure the performance of the system. Both pressure and position feedback were tested. The pressure feedback performed as well as position feedback implying that the actuator, with a break frequency on the order of 10 Rad/sec, was the limiting component. Theoretical considerations indicate that aerodynamic lags will not appear below frequencies of 50 Rad/sec, or higher.

Application of differential similarity to finding nondimensional groups important in tests of cooled engine components

NASA Technical Reports Server (NTRS)

Sucec, J.

1977-01-01

The method of differential similarity is applied to the partial differential equations and boundary conditions which govern the temperature, velocity, and pressure fields in the flowing gases and the solid stationary components in air-cooled engines. This procedure yields the nondimensional groups which must have the same value in both the test rig and the engine to produce similarity between the test results and the engine performance. These results guide the experimentalist in the design and selection of test equipment that properly scales quantities to actual engine conditions. They also provide a firm fundamental foundation for substantiation of previous similarity analyses which employed heuristic, physical reasoning arguments to arrive at the nondimensional groups.

Why climate change will invariably alter selection pressures on phenology.

PubMed

Gienapp, Phillip; Reed, Thomas E; Visser, Marcel E

2014-10-22

The seasonal timing of lifecycle events is closely linked to individual fitness and hence, maladaptation in phenological traits may impact population dynamics. However, few studies have analysed whether and why climate change will alter selection pressures and hence possibly induce maladaptation in phenology. To fill this gap, we here use a theoretical modelling approach. In our models, the phenologies of consumer and resource are (potentially) environmentally sensitive and depend on two different but correlated environmental variables. Fitness of the consumer depends on the phenological match with the resource. Because we explicitly model the dependence of the phenologies on environmental variables, we can test how differential (heterogeneous) versus equal (homogeneous) rates of change in the environmental variables affect selection on consumer phenology. As expected, under heterogeneous change, phenotypic plasticity is insufficient and thus selection on consumer phenology arises. However, even homogeneous change leads to directional selection on consumer phenology. This is because the consumer reaction norm has historically evolved to be flatter than the resource reaction norm, owing to time lags and imperfect cue reliability. Climate change will therefore lead to increased selection on consumer phenology across a broad range of situations. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

The application of alkaline lysis and pressure cycling technology in the differential extraction of DNA from sperm and epithelial cells recovered from cotton swabs.

PubMed

Nori, Deepthi V; McCord, Bruce R

2015-09-01

This study reports the development of a two-step protocol using pressure cycling technology (PCT) and alkaline lysis for differential extraction of DNA from mixtures of sperm and vaginal epithelial cells recovered from cotton swabs. In controlled experiments, in which equal quantities of sperm and female epithelial cells were added to cotton swabs, 5 min of pressure pulsing in the presence of 0.4 M NaOH resulted in 104 ± 6% recovery of female epithelial DNA present on the swab. Following the pressure treatment, exposing the swabs to a second 5-min alkaline treatment at 95 °C without pressure resulted in the selective recovery of 69 ± 6% of the sperm DNA. The recovery of the vaginal epithelia and sperm DNA was optimized by examining the effect of sodium hydroxide concentration, incubation temperature, and time. Following the alkaline lysis steps, the samples were neutralized with 2 M Tris (pH 7.5) and purified with phenol-chloroform-isoamyl alcohol to permit downstream analysis. The total processing time to remove both fractions from the swab was less than 20 min. Short tandem repeat (STR) analysis of these fractions obtained from PCT treatment and alkaline lysis generated clean profiles of female epithelial DNA and male sperm DNA for 1:1 mixtures of female and male cells and predominant male profiles for mixtures up to 5:1 female to male cells. By reducing the time and increasing the recovery of DNA from cotton swabs, this new method presents a novel and potentially useful procedure for forensic differential extractions.

Inferring differential evolutionary processes of plant persistence traits in Northern Hemisphere Mediterranean fire-prone ecosystems

USGS Publications Warehouse

Pausas, J.G.; Keeley, J.E.; Verdu, M.

2006-01-01

1 Resprouting capacity (R) and propagule-persistence (P) are traits that are often considered to have evolved where there are predictable crown fires. Because several indicators suggest a stronger selective pressure for such traits in California than in the Mediterranean Basin, we hypothesize that plant species should have evolved to become R+ and P+ more frequently in California than in the Mediterranean Basin. 2 To test this hypothesis we studied the phylogenetic association between R and P states in both California and the Mediterranean Basin using published molecular phylogenies. 3 The results suggest that R and P evolved differently in the two regions. The occurrence of the states differs significantly between regions for trait P, but not for trait R. The different patterns (towards R+ and P+ in California and towards R+ and P- in the Mediterranean Basin) are reflected in the higher abundance and the wider taxonomic distribution of species with both persistence traits (R+P+ species) in California. 4 The differential acquisition of fire persistence mechanisms at the propagule level (P+) supports the idea that fire selective pressures has been higher in California than in the Mediterranean Basin. 5 Our comparative phylogenetic-informed analysis contributes to an understanding of the differential role of the Quaternary climate in determining fire persistence traits in different Mediterranean-type ecosystems and, thus, to the debate on the evolutionary convergence of traits. ?? 2006 British Ecological Society.

Evaluation of MIL-L-23699 Lubricant Performance in the TF41-A-2 Engine

DTIC Science & Technology

1975-05-01

provides the necessary signals to the cockpit indicator for the indication of engine oil pressure. The differential pressure switch controls a cockpit...light. If the light is on, it indicates that the differential oil pressure is low. The setting ot the differential pressure switch is 11 t 1 psi. The

Deformation and stress response of composite laminated shells under internal pressure

NASA Technical Reports Server (NTRS)

Yuan, F. G.

1991-01-01

This paper presents a theoretical study of the response of filament wound composite shells under internal pressure. Each layer of the material is generally cylindrically anisotropic. By using cylindrically anisotropic elasticity field equations and Lekhnitskii's stress functions, a system of sixth-order ordinary differential equations is obtained. The general expressions for the stresses and displacements in the laminated composite shells under internal pressure are discussed. Two composite systems, graphite/epoxy and glass/epoxy, are selected to demonstrate the influence of degree of material anisotropy and fiber orientations on the axial and induced twisting deformation. Stress distributions of (45/-45)s symmetric angle-ply fiber-reinforced laminated shells are shown to illustrate the effect of radius-to-thickness ratio.

High-resolution manometry combined with impedance measurements discriminates the cause of dysphagia in children.

PubMed

Rommel, Nathalie; Omari, Taher I; Selleslagh, Margot; Kritas, Stamatiki; Cock, Charles; Rosan, Rachel; Rodriguez, Leonel; Nurko, Samuel

2015-12-01

Pressure-flow analysis allows assessing esophageal bolus transport in relation to esophageal pressures. This study aimed to characterize pressure-flow metrics in relation to dysphagia in paediatric patients. We analysed esophageal pressure-impedance recordings of 5 ml liquid and viscous swallows from 35 children (17 M, mean 10.5 ± 0.8 years). Primary indication for referral was gastroesophageal reflux disease (GERD) (9), post-fundoplication dysphagia (5), idiopathic dysphagia (16), trachea-esophageal fistula (2) and other (3). Peristaltic function was assessed using the 20 mmHg iso-contour defect and the timing between bolus pressure and flow was assessed using the Pressure Flow Index, a metric elevated in relation to dysphagia. Patients were stratified in relation to dysphagia and to peristaltic defect size. Dysphagia was characterized by a weaker peristalsis for liquids and higher Pressure Flow Index for viscous. When patients were stratified based on weak or normal peristalsis, dysphagia with weak peristalsis related to a larger iso-contour defect size and dysphagia with normal peristalsis related to higher Pressure Flow Index. Pressure-flow analysis enables differentiation of patients with dysphagia due to weak peristalsis (poor bolus clearance) from abnormal bolus flow resistance (esophageal outflow obstruction). This new dichotomous categorization of esophageal function may help guide the selection of optimal treatment such as pharmacological or endoscopic therapy. • Pressure-flow analysis (PFA) can detect abnormalities in esophageal motility using integrated analysis of bolus propulsion and bolus flow during swallowing. • AIM analysis has recently been reported to be useful in identifying subtle pre-operative esophageal dysfunction in adult patients who developed post-fundoplication dysphagia as well as in patients with non-obstructive dysphagia. • Pressure-flow parameters can distinguish the cause of dysphagia in paediatric patients. • Combined high-resolution manometry and impedance measurements with pressure-flow analysis can differentiate paediatric patients with dysphagia symptoms in relation to either weak peristalsis (poor bolus clearance) or over-pressurization (abnormal bolus flow resistance). HOW MIGHT IT IMPACT ON CLINICAL PRACTICE IN THE FUTURE? • This study supports the use of a novel objective analysis method on recordings that are readily used in paediatric clinical practice. • The pressure-flow approach allows discriminating esophageal dysfunction in relation to dysphagia symptoms in children. This has not been achieved in children with current analysis methods. • The new findings of this study allow a dichotomous categorization of esophageal function, which may help to guide the selection of the most optimal treatment such as pharmacological or endoscopic therapy.

Immunogenetic Variation and Differential Pathogen Exposure in Free-Ranging Cheetahs across Namibian Farmlands

PubMed Central

Castro-Prieto, Aines; Wachter, Bettina; Melzheimer, Joerg; Thalwitzer, Susanne; Hofer, Heribert; Sommer, Simone

2012-01-01

Background Genes under selection provide ecologically important information useful for conservation issues. Major histocompatibility complex (MHC) class I and II genes are essential for the immune defence against pathogens from intracellular (e.g. viruses) and extracellular (e.g. helminths) origins, respectively. Serosurvey studies in Namibian cheetahs (Acinonyx juabuts) revealed higher exposure to viral pathogens in individuals from north-central than east-central regions. Here we examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs. Methodology/Principal Findings Genetic variation at MHC I and II loci was assessed through single-stranded conformation polymorphism (SSCP) analysis and sequencing. While the overall allelic diversity did not differ, we observed a high genetic differentiation at MHC class I loci between cheetahs from north-central and east-central Namibia. No such differentiation in MHC class II and neutral markers were found. Conclusions/Significance Our results suggest that MHC class I variation mirrors the variation in selection pressure imposed by viruses in free-ranging cheetahs across Namibian farmland. This is of high significance for future management and conservation programs of this species. PMID:23145096

Immunogenetic variation and differential pathogen exposure in free-ranging cheetahs across Namibian farmlands.

PubMed

Castro-Prieto, Aines; Wachter, Bettina; Melzheimer, Joerg; Thalwitzer, Susanne; Hofer, Heribert; Sommer, Simone

2012-01-01

Genes under selection provide ecologically important information useful for conservation issues. Major histocompatibility complex (MHC) class I and II genes are essential for the immune defence against pathogens from intracellular (e.g. viruses) and extracellular (e.g. helminths) origins, respectively. Serosurvey studies in Namibian cheetahs (Acinonyx juabuts) revealed higher exposure to viral pathogens in individuals from north-central than east-central regions. Here we examined whether the observed differences in exposure to viruses influence the patterns of genetic variation and differentiation at MHC loci in 88 free-ranging Namibian cheetahs. Genetic variation at MHC I and II loci was assessed through single-stranded conformation polymorphism (SSCP) analysis and sequencing. While the overall allelic diversity did not differ, we observed a high genetic differentiation at MHC class I loci between cheetahs from north-central and east-central Namibia. No such differentiation in MHC class II and neutral markers were found. Our results suggest that MHC class I variation mirrors the variation in selection pressure imposed by viruses in free-ranging cheetahs across Namibian farmland. This is of high significance for future management and conservation programs of this species.

Patterns of Positive Selection of the Myogenic Regulatory Factor Gene Family in Vertebrates

PubMed Central

Zhao, Xiao; Yu, Qi; Huang, Ling; Liu, Qing-Xin

2014-01-01

The functional divergence of transcriptional factors is critical in the evolution of transcriptional regulation. However, the mechanism of functional divergence among these factors remains unclear. Here, we performed an evolutionary analysis for positive selection in members of the myogenic regulatory factor (MRF) gene family of vertebrates. We selected 153 complete vertebrate MRF nucleotide sequences from our analyses, which revealed substantial evidence of positive selection. Here, we show that sites under positive selection were more frequently detected and identified from the genes encoding the myogenic differentiation factors (MyoG and Myf6) than the genes encoding myogenic determination factors (Myf5 and MyoD). Additionally, the functional divergence within the myogenic determination factors or differentiation factors was also under positive selection pressure. The positive selection sites were more frequently detected from MyoG and MyoD than Myf6 and Myf5, respectively. Amino acid residues under positive selection were identified mainly in their transcription activation domains and on the surface of protein three-dimensional structures. These data suggest that the functional gain and divergence of myogenic regulatory factors were driven by distinct positive selection of their transcription activation domains, whereas the function of the DNA binding domains was conserved in evolution. Our study evaluated the mechanism of functional divergence of the transcriptional regulation factors within a family, whereby the functions of their transcription activation domains diverged under positive selection during evolution. PMID:24651579

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.

Hydrostatic pressure-dependent changes in cyclic AMP signaling in optic nerve head astrocytes from Caucasian and African American donors

PubMed Central

Chen, Lin; Hernandez, M. Rosario

2009-01-01

Purpose Investigate the effect of hydrostatic pressure (HP) on 3′, 5′-cyclic adenosine monophosphate (cAMP) levels and downstream signaling in cultures of normal optic nerve head (ONH) astrocytes from Caucasian American (CA) and African American (AA) donors. Methods Intracellular cAMP levels were assayed after exposing ONH astrocytes to HP for varying times. Quantitative RT–PCR was used to determine the expression levels of selected cAMP pathway genes in human ONH astrocytes after HP treatment. Western blots were used to measure changes in the phosphorylation state of cAMP response element binding protein (CREB) in astrocytes subjected to HP, ATP, and phosphodiesterase or kinase inhibitors. Results The basal intracellular cAMP level is similar among AA and CA astrocytes. After exposure to HP for 15 min and 30 min in the presence of a phosphodiesterase inhibitor a further increase of intracellular cAMP was observed in AA astrocytes, but not in CA astrocytes. Consistent with activation of the cAMP-dependent protein kinase pathway, CREB phosphorylation (Ser-133) was increased to a greater extent in AA than in CA astrocytes after 3 h of HP. Exposure to elevated HP for 3–6 h differentially altered the expression levels of selected cAMP pathway genes (ADCY3, ADCY9, PTHLH, PDE7B) in AA compared to CA astrocytes. Treatment with ATP increased more CREB phosphorylation in CA than in AA astrocytes, suggesting differential Ca2+ signaling in these populations. Conclusions Activation of the cAMP-dependent signaling pathway by pressure may be an important contributor to increased susceptibility to elevated intraocular pressure and glaucoma in AA, a population at higher risk for the disease. PMID:19710943

Fracture Sustainability Pressure, Temperature, Differential Pressure, and Aperture Closure Data

DOE Data Explorer

Tim Kneafsey

2016-09-30

In these data sets, the experiment time, actual date and time, room temperature, sample temperature, upstream and downstream pressures (measured independently), corrected differential pressure (measured independently and corrected for offset and room temperature) indication of aperture closure by linear variable differential transformer are presented. An indication of the sample is in the file name and in the first line of data.

Differential pressure distribution measurement for the development of insect-sized wings

NASA Astrophysics Data System (ADS)

Takahashi, Hidetoshi; Matsumoto, Kiyoshi; Shimoyama, Isao

2013-05-01

This paper reports on the measurement of the differential pressure distribution over a flat, thin wing using a micro-electro-mechanical systems sensor. Sensors featuring a piezoresistive cantilever were attached to a polyimide/Cu wing. Because the weight of the cantilever element was less than 10 ng, the sensor can measure the differential pressure without interference from inertial forces, such as wing flapping motions. The dimensions of the sensor chips and the wing were 1.0 mm × 1.0 mm × 0.3 mm and 100 mm × 30 mm × 1 mm, respectively. The differential pressure distribution along the wing's chord direction was measured in a wind tunnel at an air velocity of 4.0 m s­-1 by changing the angle of attack. It was confirmed that the pressure coefficient calculated by the measured differential pressure distribution was similar to the value measured by a load cell.

Selective neuronal differentiation of neural stem cells induced by nanosecond microplasma agitation.

PubMed

Xiong, Z; Zhao, S; Mao, X; Lu, X; He, G; Yang, G; Chen, M; Ishaq, M; Ostrikov, K

2014-03-01

An essential step for therapeutic and research applications of stem cells is their ability to differentiate into specific cell types. Neuronal cells are of great interest for medical treatment of neurodegenerative diseases and traumatic injuries of central nervous system (CNS), but efforts to produce these cells have been met with only modest success. In an attempt of finding new approaches, atmospheric-pressure room-temperature microplasma jets (MPJs) are shown to effectively direct in vitro differentiation of neural stem cells (NSCs) predominantly into neuronal lineage. Murine neural stem cells (C17.2-NSCs) treated with MPJs exhibit rapid proliferation and differentiation with longer neurites and cell bodies eventually forming neuronal networks. MPJs regulate ~75% of NSCs to differentiate into neurons, which is a higher efficiency compared to common protein- and growth factors-based differentiation. NSCs exposure to quantized and transient (~150 ns) micro-plasma bullets up-regulates expression of different cell lineage markers as β-Tubulin III (for neurons) and O4 (for oligodendrocytes), while the expression of GFAP (for astrocytes) remains unchanged, as evidenced by quantitative PCR, immunofluorescence microscopy and Western Blot assay. It is shown that the plasma-increased nitric oxide (NO) production is a factor in the fate choice and differentiation of NSCs followed by axonal growth. The differentiated NSC cells matured and produced mostly cholinergic and motor neuronal progeny. It is also demonstrated that exposure of primary rat NSCs to the microplasma leads to quite similar differentiation effects. This suggests that the observed effect may potentially be generic and applicable to other types of neural progenitor cells. The application of this new in vitro strategy to selectively differentiate NSCs into neurons represents a step towards reproducible and efficient production of the desired NSC derivatives. Published by Elsevier B.V.

The investigation of parachute fabric permeability under an unsteady pressure differential

NASA Astrophysics Data System (ADS)

Rondeau, Nichole C.

An apparatus for assessing permeability of textiles subjected to time-varying pressure differentials is presented. A Computer Numerically Controlled Piston Permeability Apparatus (CNC-PPA) that can control the volume flow rate through a fabric has been designed and built. This test device has been developed in an effort to improve the understanding and design choices for aerodynamic decelerators. Preliminary results for a low permeability fabric (PIA-C-44378, Type IV) under both steady and unsteady loads are presented. The results from this investigation do indicate a small effect of unsteady pressure differential on the fabric permeability. The fabric permeability is slightly higher than the static permeability when the pressure differential is increasing with respect to time and the opposite is true when the pressure differential is decreasing. This change in permeability is more pronounced as the pressure is higher and the pressure changes more rapidly with respect to time, suggesting dynamic permeability likely affects highly unsteady phenomena such as parachute opening.

Relative contributions of neutral and non-neutral processes to clinal variation in calyx lobe length in the series Sakawanum (Asarum: Aristolochiaceae).

PubMed

Takahashi, Daiki; Teramine, Tsutomu; Sakaguchi, Shota; Setoguchi, Hiroaki

2018-01-25

Clines, the gradual variation in measurable traits along a geographical axis, play a major role in evolution and can contribute to our understanding of the relative roles of selective and neutral process in trait variation. Using genetic and morphological analyses, the relative contributions of neutral and non-neutral processes were explored to infer the evolutionary history of species of the series Sakawanum (genus Asarum), which shows significant clinal variation in calyx lobe length. A total of 27 populations covering the natural geographical distribution of the series Sakawanum were sampled. Six nuclear microsatellite markers were used to investigate genetic structure and genetic diversity. The lengths of calyx lobes of multiple populations were measured to quantify their geographical and taxonomic differentiation. To detect the potential impact of selective pressure, morphological differentiation was compared with genetic differentiation (QCT-FST comparison). Average calyx lobe length of A. minamitanianum was 124.11 mm, while that of A. costatum was 13.80 mm. Though gradually changing along the geographical axis within series, calyx lobe lengths were significantly differentiated among the taxa. Genetic differentiation between taxa was low (FST = 0.099), but a significant geographical structure along the morphological cline was detected. Except for one taxon pair, pairwise QCT values were significantly higher than the neutral genetic measures of FST and G'ST. Divergent selection may have driven the calyx lobe length variation in series Sakawanum taxa, although the underlying mechanism is still not clear. The low genetic differentiation indicates recent divergence and/or gene flows between geographically close taxa. These neutral processes would also affect the clinal variation in calyx lobe lengths. Overall, this study implies the roles of population history and divergent selection in shaping the current cline of a flower trait in the series Sakawanum. © The Author(s) 2017. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Differential evolution enhanced with multiobjective sorting-based mutation operators.

PubMed

Wang, Jiahai; Liao, Jianjun; Zhou, Ying; Cai, Yiqiao

2014-12-01

Differential evolution (DE) is a simple and powerful population-based evolutionary algorithm. The salient feature of DE lies in its mutation mechanism. Generally, the parents in the mutation operator of DE are randomly selected from the population. Hence, all vectors are equally likely to be selected as parents without selective pressure at all. Additionally, the diversity information is always ignored. In order to fully exploit the fitness and diversity information of the population, this paper presents a DE framework with multiobjective sorting-based mutation operator. In the proposed mutation operator, individuals in the current population are firstly sorted according to their fitness and diversity contribution by nondominated sorting. Then parents in the mutation operators are proportionally selected according to their rankings based on fitness and diversity, thus, the promising individuals with better fitness and diversity have more opportunity to be selected as parents. Since fitness and diversity information is simultaneously considered for parent selection, a good balance between exploration and exploitation can be achieved. The proposed operator is applied to original DE algorithms, as well as several advanced DE variants. Experimental results on 48 benchmark functions and 12 real-world application problems show that the proposed operator is an effective approach to enhance the performance of most DE algorithms studied.

Signatures of Diversifying Selection in European Pig Breeds

PubMed Central

Wilkinson, Samantha; Lu, Zen H.; Megens, Hendrik-Jan; Archibald, Alan L.; Haley, Chris; Jackson, Ian J.; Groenen, Martien A. M.; Crooijmans, Richard P. M. A.; Ogden, Rob; Wiener, Pamela

2013-01-01

Following domestication, livestock breeds have experienced intense selection pressures for the development of desirable traits. This has resulted in a large diversity of breeds that display variation in many phenotypic traits, such as coat colour, muscle composition, early maturity, growth rate, body size, reproduction, and behaviour. To better understand the relationship between genomic composition and phenotypic diversity arising from breed development, the genomes of 13 traditional and commercial European pig breeds were scanned for signatures of diversifying selection using the Porcine60K SNP chip, applying a between-population (differentiation) approach. Signatures of diversifying selection between breeds were found in genomic regions associated with traits related to breed standard criteria, such as coat colour and ear morphology. Amino acid differences in the EDNRB gene appear to be associated with one of these signatures, and variation in the KITLG gene may be associated with another. Other selection signals were found in genomic regions including QTLs and genes associated with production traits such as reproduction, growth, and fat deposition. Some selection signatures were associated with regions showing evidence of introgression from Asian breeds. When the European breeds were compared with wild boar, genomic regions with high levels of differentiation harboured genes related to bone formation, growth, and fat deposition. PMID:23637623

Reliability of Pressure Ulcer Rates: How Precisely Can We Differentiate Among Hospital Units, and Does the Standard Signal‐Noise Reliability Measure Reflect This Precision?

PubMed Central

Cramer, Emily

2016-01-01

Abstract Hospital performance reports often include rankings of unit pressure ulcer rates. Differentiating among units on the basis of quality requires reliable measurement. Our objectives were to describe and apply methods for assessing reliability of hospital‐acquired pressure ulcer rates and evaluate a standard signal‐noise reliability measure as an indicator of precision of differentiation among units. Quarterly pressure ulcer data from 8,199 critical care, step‐down, medical, surgical, and medical‐surgical nursing units from 1,299 US hospitals were analyzed. Using beta‐binomial models, we estimated between‐unit variability (signal) and within‐unit variability (noise) in annual unit pressure ulcer rates. Signal‐noise reliability was computed as the ratio of between‐unit variability to the total of between‐ and within‐unit variability. To assess precision of differentiation among units based on ranked pressure ulcer rates, we simulated data to estimate the probabilities of a unit's observed pressure ulcer rate rank in a given sample falling within five and ten percentiles of its true rank, and the probabilities of units with ulcer rates in the highest quartile and highest decile being identified as such. We assessed the signal‐noise measure as an indicator of differentiation precision by computing its correlations with these probabilities. Pressure ulcer rates based on a single year of quarterly or weekly prevalence surveys were too susceptible to noise to allow for precise differentiation among units, and signal‐noise reliability was a poor indicator of precision of differentiation. To ensure precise differentiation on the basis of true differences, alternative methods of assessing reliability should be applied to measures purported to differentiate among providers or units based on quality. © 2016 The Authors. Research in Nursing & Health published by Wiley Periodicals, Inc. PMID:27223598

Measurement of the differential pressure of liquid metals

DOEpatents

Metz, H.J.

1975-09-01

This patent relates to an improved means for measuring the differential pressure between any two points in a process liquid metal coolant loop, wherein the flow of liquid metal in a pipe is opposed by a permanent magnet liquid metal pump until there is almost zero flow shown by a magnetic type flowmeter. The pressure producing the liquid metal flow is inferred from the rate of rotation of the permanent magnet pump. In an alternate embodiment, a differential pressure transducer is coupled to a process pipeline by means of high-temperature bellows or diaphragm seals, and a permanent magnet liquid metal pump in the high-pressure transmission line to the pressure transducer can be utilized either for calibration of the transducer or for determining the process differential pressure as a function of the magnet pump speed. (auth)

Vapor Pressure Data and Analysis for Selected HD Decomposition Products: 1,4-Thioxane, Divinyl Sulfoxide, Chloroethyl Acetylsulfide, and 1,4-Dithiane

DTIC Science & Technology

2018-06-01

decomposition products from bis-(2-chloroethyl) sulfide (HD). These data were measured using an ASTM International method that is based on differential...2.1 Materials and Method ........................................................................................2 2.2 Data Analysis...and Method The source and purity of the materials studied are listed in Table 1. Table 1. Sample Information for Title Compounds Compound

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

Spatial Characteristics of the Unsteady Differential Pressures on 16 percent F/A-18 Vertical Tails

NASA Technical Reports Server (NTRS)

Moses, Robert W.; Ashley, Holt

1998-01-01

Buffeting is an aeroelastic phenomenon which plagues high performance aircraft at high angles of attack. For the F/A-18 at high angles of attack, vortices emanating from wing/fuselage leading edge extensions burst, immersing the vertical tails in their turbulent wake. The resulting buffeting of the vertical tails is a concern from fatigue and inspection points of view. Previous flight and wind-tunnel investigations to determine the buffet loads on the tail did not provide a complete description of the spatial characteristics of the unsteady differential pressures. Consequently, the unsteady differential pressures were considered to be fully correlated in the analyses of buffet and buffeting. The use of fully correlated pressures in estimating the generalized aerodynamic forces for the analysis of buffeting yielded responses that exceeded those measured in flight and in the wind tunnel. To learn more about the spatial characteristics of the unsteady differential pressures, an available 16%, sting-mounted, F-18 wind-tunnel model was modified and tested in the Transonic Dynamics Tunnel (TDT) at the NASA Langley Research Center as part of the ACROBAT (Actively Controlled Response Of Buffet-Affected Tails) program. Surface pressures were measured at high angles of attack on flexible and rigid tails. Cross-correlation and cross-spectral analyses of the pressure time histories indicate that the unsteady differential pressures are not fully correlated. In fact, the unsteady differential pressure resemble a wave that travels along the tail. At constant angle of attack, the pressure correlation varies with flight speed.

The effect of hydrostatic pressure on staurosporine-induced neural differentiation in mouse bone marrow‑derived mesenchymal stem cells.

PubMed

Javanmard, F; Azadbakht, M; Pourmoradi, M

2016-01-01

In this study, the role of hydrostatic pressure on staurosporine-induced neural differentiation in mouse bone marrow mesenchymal stem cells were investigated. The cells were cultured in treatment medium containing 100 nM of staurosporine for 4 hours; then the cells were affected by hydrostatic pressure (0, 25,50, 100 mmHg). The percentage of cell viability by trypan blue staining and the percentage of cell death by Hoechst/PI differential staining were assessed. We obtained the total neurite length. Expression of β-tubulin III and GFAP (Glial fibrillary acidic protein) proteins were also analyzed by immunocytochemistry. The percentage of cell viability in treatments decreased relative to the increase in hydrostatic pressure and time (p Keywords: bone marrow mesenchymal stem cell, hydrostatic pressure, immunocytochemistry, neural differentiation, neurite length, cell differentiation.

Allele frequencies of variants in ultra conserved elements identify selective pressure on transcription factor binding.

PubMed

Silla, Toomas; Kepp, Katrin; Tai, E Shyong; Goh, Liang; Davila, Sonia; Catela Ivkovic, Tina; Calin, George A; Voorhoeve, P Mathijs

2014-01-01

Ultra-conserved genes or elements (UCGs/UCEs) in the human genome are extreme examples of conservation. We characterized natural variations in 2884 UCEs and UCGs in two distinct populations; Singaporean Chinese (n = 280) and Italian (n = 501) by using a pooled sample, targeted capture, sequencing approach. We identify, with high confidence, in these regions the abundance of rare SNVs (MAF<0.5%) of which 75% is not present in dbSNP137. UCEs association studies for complex human traits can use this information to model expected background variation and thus necessary power for association studies. By combining our data with 1000 Genome Project data, we show in three independent datasets that prevalent UCE variants (MAF>5%) are more often found in relatively less-conserved nucleotides within UCEs, compared to rare variants. Moreover, prevalent variants are less likely to overlap transcription factor binding site. Using SNPfold we found no significant influence of RNA secondary structure on UCE conservation. All together, these results suggest UCEs are not under selective pressure as a stretch of DNA but are under differential evolutionary pressure on the single nucleotide level.

Balloon-Supported Loran Antenna, New Hardware for Tethered Balloons, and Payloads Used in BAMM Flights.

DTIC Science & Technology

1980-02-28

containing a command receiver, batteries, and a differential- pressure switch , all located immediately below the confluence point, with long leads and a...should break free, or during normal deflation at take- down. Purpose of the differential- pressure switch was to momentarily open the valves if the...otherwise was completely different. A differential- pressure switch of the type formerly used in the command package, but without the long pressure

Evidence of Adaptive Evolution and Relaxed Constraints in Sex-Biased Genes of South American and West Indies Fruit Flies (Diptera: Tephritidae)

PubMed Central

Campanini, Emeline B; Torres, Felipe R; Rezende, Víctor B; Nakamura, Aline M; de Oliveira, Janaína L; Lima, André L A; Chahad-Ehlers, Samira; Sobrinho, Iderval S; de Brito, Reinaldo A

2018-01-01

Abstract Several studies have demonstrated that genes differentially expressed between sexes (sex-biased genes) tend to evolve faster than unbiased genes, particularly in males. The reason for this accelerated evolution is not clear, but several explanations have involved adaptive and nonadaptive mechanisms. Furthermore, the differences of sex-biased expression patterns of closely related species are also little explored out of Drosophila. To address the evolutionary processes involved with sex-biased expression in species with incipient differentiation, we analyzed male and female transcriptomes of Anastrepha fraterculus and Anastrepha obliqua, a pair of species that have diverged recently, likely in the presence of gene flow. Using these data, we inferred differentiation indexes and evolutionary rates and tested for signals of selection in thousands of genes expressed in head and reproductive transcriptomes from both species. Our results indicate that sex-biased and reproductive-biased genes evolve faster than unbiased genes in both species, which is due to both adaptive pressure and relaxed constraints. Furthermore, among male-biased genes evolving under positive selection, we identified some related to sexual functions such as courtship behavior and fertility. These findings suggest that sex-biased genes may have played important roles in the establishment of reproductive isolation between these species, due to a combination of selection and drift, and unveil a plethora of genetic markers useful for more studies in these species and their differentiation. PMID:29346618

Genetic diversity of the NE Atlantic sea urchin Strongylocentrotus droebachiensis unveils chaotic genetic patchiness possibly linked to local selective pressure.

PubMed

Norderhaug, K M; Anglès d'Auriac, M B; Fagerli, C W; Gundersen, H; Christie, H; Dahl, K; Hobæk, A

We compared the genetic differentiation in the green sea urchin Strongylocentrotus droebachiensis from discrete populations on the NE Atlantic coast. By using eight recently developed microsatellite markers, genetic structure was compared between populations from the Danish Strait in the south to the Barents Sea in the north (56-79°N). Urchins are spread by pelagic larvae and may be transported long distances by northwards-going ocean currents. Two main superimposed patterns were identified. The first showed a subtle but significant genetic differentiation from the southernmost to the northernmost of the studied populations and could be explained by an isolation by distance model. The second pattern included two coastal populations in mid-Norway (65°N), NH and NS, as well as the northernmost population of continental Norway (71°N) FV. They showed a high degree of differentiation from all other populations. The explanation to the second pattern is most likely chaotic genetic patchiness caused by introgression from another species, S. pallidus, into S. droebachiensis resulting from selective pressure. Ongoing sea urchin collapse and kelp forests recovery are observed in the area of NH, NS and FV populations. High gene flow between populations spanning more than 22° in latitude suggests a high risk of new grazing events to occur rapidly in the future if conditions for sea urchins are favourable. On the other hand, the possibility of hybridization in association with collapsing populations may be used as an early warning indicator for monitoring purposes.

Preliminary Engineering Design Package for the Basin A Neck Groundwater Intercept and Treatment System Interim Response Action

DTIC Science & Technology

1989-02-01

INDICATOR pPOST-FILTERED VITER RPUESIC POST-FILTRATION POLYMER SOLUTION MCUUM BREAKER FILTRATION POLYMER D*+RENTALkL PRESSURE SWITCH FEED PUMPS POLYMER...differential pressure switch signals the need for backwash of the operating filter. At this time, flow is S automatically switched to the standby filter...filter is undergoing backwash or on standby. High differential pressure across the filter bed, as sensed by a differential pressure switch , signals

Elastic properties of overpressured and unconsolidated sediments

USGS Publications Warehouse

Lee, Myung W.

2003-01-01

Differential pressure affects elastic velocities and Poisson?s ratio of sediments in such a way that velocities increase as differential pressure increases. Overpressured zones in sediments can be detected by observing an increase in Poisson?s ratio with a corresponding drop in elastic velocities. In highly overpressured sands, such as shallow water flow sands, the P-to S-wave velocity ratio (Vp/Vs) is very high, on the order of 10 or higher, due to the unconsolidated and uncemented nature of sediments. In order to predict elastic characteristics of highly overpressured sands, Biot-Gassmann theory by Lee (BGTL) is used with a variable exponent n that depends on differential pressure and the degree of consolidation/compaction. The exponent n decreases as differential pressure and the degree of consolidation increases, and, as n decreases, velocity increases and Vp/Vs decreases. The predicted velocity ratio by BGTL agrees well with the measured velocity ratio at low differential pressure for unconsolidated sediments.

Simulation analysis and experimental verification of spiral-tube-type valveless piezoelectric pump with gyroscopic effect

NASA Astrophysics Data System (ADS)

Leng, Xuefei; Zhang, Jianhui; Jiang, Yan; Wang, Shouyin; Zhao, Chunsheng

2014-07-01

The current research of the valveless piezoelectric pump focuses on increasing the flow rate and pressure differential. Compared with the valve piezoelectric pump, the valveless one has excellent performances in simple structure, low cost, and easy miniaturization. So, their important development trend is the mitigation of their weakness, and the multi-function integration. The flow in a spiral tube element is sensitive to the element attitude caused by the Coriolis force, and that a valveless piezoelectric pump is designed by applying this phenomenon. The pump has gyroscopic effect, and has both the actuator function of fluid transfer and the sensor function, which can obtain the angular velocity when its attitude changes. First, the present paper analyzes the flow characteristics in the tube, obtains the calculation formula for the pump flow, and identifies the relationship between pump attitude and flow, which clarifies the impact of flow and driving voltage, frequency, spiral line type and element attitude, and verifies the gyroscopic effect of the pump. Then, the finite element simulation is used to verify the theory. Finally, a pump is fabricated for experimental testing of the relationship between pump attitude and pressure differential. Experimental results show that when Archimedes spiral θ=4π is selected for the tube design, and the rotation speed of the plate is 70 r/min, the pressure differential is 88.2 Pa, which is 1.5 times that of 0 r/min rotation speed. The spiral-tube-type valveless piezoelectric pump proposed can turn the element attitude into a form of pressure output, which is important for the multi-function integration of the valveless piezoelectric pump and for the development of civil gyroscope in the future.

Selected Physical Properties of 2-Chloroethyl-3-Chloropropyl Sulfide (CECPRS)

DTIC Science & Technology

2010-10-01

Analysis * For this work, a TA Instruments 910 Differential Scanning Calorimeter and 2200 Controller were used. Prior to sample measurements, the DSC...controlled mass flow rate over a known time, concentrated, and the mass quantified by GC-FID analysis . This step enables vapor pressure measurements for low...Bellefonte, PA), with a 1.0 (im RTx-1 ( polydimethylsiloxane ) stationary phase, was maintained at 40 °C for 2 min following sample introduction, then heated

Operation of mixed conducting metal oxide membrane systems under transient conditions

DOEpatents

Carolan, Michael Francis [Allentown, PA

2008-12-23

Method of operating an oxygen-permeable mixed conducting membrane having an oxidant feed side, an oxidant feed surface, a permeate side, and a permeate surface, which method comprises controlling the differential strain between the permeate surface and the oxidant feed surface at a value below a selected maximum value by varying the oxygen partial pressure on either or both of the oxidant feed side and the permeate side of the membrane.

Compartment syndrome and shin splints of the lower leg.

PubMed

Gerow, G; Matthews, B; Jahn, W; Gerow, R

1993-05-01

The objective of this article is to review and categorize the current knowledge on compartment syndromes (CS) and shin splints (SS), with specific importance relegated to the diagnosis, differential diagnosis and management of these conditions. The bibliographic data sources reviewed are limited to the English language and human content and are from medical and scientific journals, as well as chiropractic and medical texts. A mini-Medline version of Index Medicus was utilized. Terms for indexing included compartment syndromes, shin splints and stress fractures. The bibliographies of the journals selected were then evaluated and, where appropriate, the specific journal or text references regarding diagnosis and management were then reviewed. This information was then included in this article, where useful, to further clarify or reference statements made. Differential diagnosis of the acute CS from chronic CS and SS requires clinical methods and imaging procedures. The pathogenesis of the acute CS of the lower leg is associated with external pressure or internal hemorrhage. If the tissue pressure were to rise above 30-40 mm Hg for 4-12 h, irreversible muscular damage would result. Emergency surgical intervention is the only appropriate form of treatment in acute CS. In chronic CS, where elevated pressures exist on a transient basis, influenced by activity, conservative management procedures are felt to be effective. However, if these methods are not helpful, surgical intervention may be necessary. The etiology of pain associated with SS is not associated with compartmental pressure elevations, but rather, results from periostitis occurring along the tibia caused by muscular and tendinous strain associated with inflammation. Conservative management is most appropriate for this disorder, with surgical intervention being an uncommon treatment approach. Although clinical findings are useful in the diagnosis of these disorders, fluid pressure findings may be necessary to fully differentiate acute CS from other disorders. Up until recently, common methods of obtaining pressure measurements of compartments included the use of a needle manometer. More recently, however, a hand-held miniature fluid pressure monitor has been developed that produces reproducible measurements of interstitial fluid, making testing potentially practical for the clinician.

Detection of Radiation-Exposure Biomarkers by Differential Mobility Prefiltered Mass Spectrometry (DMS-MS)

PubMed Central

Coy, Stephen L.; Krylov, Evgeny V.; Schneider, Bradley B.; Covey, Thomas R.; Brenner, David J.; Tyburski, John B.; Patterson, Andrew D.; Krausz, Kris W.; Fornace, Albert J.; Nazarov, Erkinjon G.

2010-01-01

Technology to enable rapid screening for radiation exposure has been identified as an important need, and, as a part of a NIH / NIAD effort in this direction, metabolomic biomarkers for radiation exposure have been identified in a recent series of papers. To reduce the time necessary to detect and measure these biomarkers, differential mobility spectrometry – mass spectrometry (DMS-MS) systems have been developed and tested. Differential mobility ion filters preselect specific ions and also suppress chemical noise created in typical atmospheric-pressure ionization sources (ESI, MALDI, and others). Differential-mobility-based ion selection is based on the field dependence of ion mobility, which, in turn, depends on ion characteristics that include conformation, charge distribution, molecular polarizability, and other properties, and on the transport gas composition which can be modified to enhance resolution. DMS-MS is able to resolve small-molecule biomarkers from nearly-isobaric interferences, and suppresses chemical noise generated in the ion source and in the mass spectrometer, improving selectivity and quantitative accuracy. Our planar DMS design is rapid, operating in a few milliseconds, and analyzes ions before fragmentation. Depending on MS inlet conditions, DMS-selected ions can be dissociated in the MS inlet expansion, before mass analysis, providing a capability similar to MS/MS with simpler instrumentation. This report presents selected DMS-MS experimental results, including resolution of complex test mixtures of isobaric compounds, separation of charge states, separation of isobaric biomarkers (citrate and isocitrate), and separation of nearly-isobaric biomarker anions in direct analysis of a bio-fluid sample from the radiation-treated group of a mouse-model study. These uses of DMS combined with moderate resolution MS instrumentation indicate the feasibility of field-deployable instrumentation for biomarker evaluation. PMID:20305793

[Single-nucleotide polymorphism in populations of sockeye salmon Oncorhynchus nerka from Kamchatka Peninsula].

PubMed

Khrustaleva, A M; Gritsenko, O F; Klovach, N V

2013-11-01

The genetic polymorphism of 45 single-nucleotide polymorphism loci was examined in the four largest wild populations of sockeye salmon Oncorhynchusnerka from drainages of the Asian coast of the Pacific Ocean (Eastern and Western Kamchatka). It was demonstrated that sockeye salmon from the Palana River were considerably different from all other populations examined. The most probable explanation of the observed differences is the suggestion on possible demographic events in the history of this population associated with the decrease in its effective number. To study the origin, colonization patterns, and evolution of Asian sockeye salmon, as well as to resolve some of the applied tasks, like population assignment and genetic identification, a differentiation approach to SNP-marker selection was suggested. Adaptively important loci that evolve under the pressure of balancing (stabilizing) selection were identified, thanks to which the number of loci that provide the baseline classification error rates in the population assignment tests was reduced to 30. It was demonstrated that SNPs located in the MHC2 and GPH genes were affected by diversifying selection. Procedures for selecting single-nucleotide polymorphisms for phylogenetic studies of Asian sockeye salmon were suggested. Using principal-component analysis, 17 loci that adequately reproduce genetic differentiation within arid among the regions of the origin of Kamchatka sockeye salmon, were selected.

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.

Genomic signature of natural and anthropogenic stress in wild populations of the waterflea Daphnia magna: validation in space, time and experimental evolution.

PubMed

Orsini, Luisa; Spanier, Katina I; DE Meester, Luc

2012-05-01

Natural populations are confronted with multiple selection pressures resulting in a mosaic of environmental stressors at the landscape level. Identifying the genetic underpinning of adaptation to these complex selection environments and assigning causes of natural selection within multidimensional selection regimes in the wild is challenging. The water flea Daphnia is a renowned ecological model system with its well-documented ecology, the possibility to analyse subfossil dormant egg banks and the short generation time allowing an experimental evolution approach. Capitalizing on the strengths of this model system, we here link candidate genome regions to three selection pressures, known to induce micro-evolutionary responses in Daphnia magna: fish predation, parasitism and land use. Using a genome scan approach in space, time and experimental evolution trials, we provide solid evidence of selection at the genome level under well-characterized environmental gradients in the wild and identify candidate genes linked to the three environmental stressors. Our study reveals differential selection at the genome level in Daphnia populations and provides evidence for repeatable patterns of local adaptation in a geographic mosaic of environmental stressors fuelled by standing genetic variation. Our results imply high evolutionary potential of local populations, which is relevant to understand the dynamics of trait changes in natural populations and their impact on community and ecosystem responses through eco-evolutionary feedbacks. © 2012 Blackwell Publishing Ltd.

Reliability of Pressure Ulcer Rates: How Precisely Can We Differentiate Among Hospital Units, and Does the Standard Signal-Noise Reliability Measure Reflect This Precision?

PubMed

Staggs, Vincent S; Cramer, Emily

2016-08-01

Hospital performance reports often include rankings of unit pressure ulcer rates. Differentiating among units on the basis of quality requires reliable measurement. Our objectives were to describe and apply methods for assessing reliability of hospital-acquired pressure ulcer rates and evaluate a standard signal-noise reliability measure as an indicator of precision of differentiation among units. Quarterly pressure ulcer data from 8,199 critical care, step-down, medical, surgical, and medical-surgical nursing units from 1,299 US hospitals were analyzed. Using beta-binomial models, we estimated between-unit variability (signal) and within-unit variability (noise) in annual unit pressure ulcer rates. Signal-noise reliability was computed as the ratio of between-unit variability to the total of between- and within-unit variability. To assess precision of differentiation among units based on ranked pressure ulcer rates, we simulated data to estimate the probabilities of a unit's observed pressure ulcer rate rank in a given sample falling within five and ten percentiles of its true rank, and the probabilities of units with ulcer rates in the highest quartile and highest decile being identified as such. We assessed the signal-noise measure as an indicator of differentiation precision by computing its correlations with these probabilities. Pressure ulcer rates based on a single year of quarterly or weekly prevalence surveys were too susceptible to noise to allow for precise differentiation among units, and signal-noise reliability was a poor indicator of precision of differentiation. To ensure precise differentiation on the basis of true differences, alternative methods of assessing reliability should be applied to measures purported to differentiate among providers or units based on quality. © 2016 The Authors. Research in Nursing & Health published by Wiley Periodicals, Inc. © 2016 The Authors. Research in Nursing & Health published by Wiley Periodicals, Inc.

Differential lung ventilation via tracheostomy using two endotracheal tubes in an infant: a case report.

PubMed

Demirkol, Demet; Ataman, Yasemin; Gündoğdu, Gökhan

2017-09-08

This case report presents differential lung ventilation in an infant. The aim is to define an alternative technique for performing differential lung ventilation in children. To the best of our knowledge, this is the first report of this kind. A 4.2-kg, 2.5-month-old Asian boy was referred to our facility with refractory hypoxemia and hypercarbia due to asymmetric lung disease with atelectasis of the left lung and hyperinflation of the right lung. He was unresponsive to conventional ventilator strategies; different ventilator settings were required. To perform differential lung ventilation, two separate single-lumen endotracheal tubes were inserted into the main bronchus of each lung by tracheotomy; the tracheal tubes were attached to discrete ventilators. The left lung was ventilated with a lung salvage strategy using high-frequency oscillatory ventilation, and the right lung was ventilated with a lung-protective strategy using pressure-regulated volume control mode. Differential lung ventilation was performed successfully with this technique without complications. Differential lung ventilation may be a lifesaving procedure in select patients who have asymmetric lung disease. Inserting two single-lumen endotracheal tubes via tracheotomy for differential lung ventilation can be an effective and safe alternative method.

Rotating pressure measurement system using an on board calibration standard

NASA Technical Reports Server (NTRS)

Senyitko, Richard G.; Blumenthal, Philip Z.; Freedman, Robert J.

1991-01-01

A computer-controlled multichannel pressure measurement system was developed to acquire detailed flow field measurements on board the Large Low Speed Centrifugal Compressor Research Facility at the NASA Lewis Research Center. A pneumatic slip ring seal assembly is used to transfer calibration pressures to a reference standard transducer on board the compressor rotor in order to measure very low differential pressures with the high accuracy required. A unique data acquisition system was designed and built to convert the analog signal from the reference transducer to the variable frequency required by the multichannel pressure measurement system and also to provide an output for temperature control of the reference transducer. The system also monitors changes in test cell barometric pressure and rotating seal leakage and provides an on screen warning to the operator if limits are exceeded. The methods used for the selection and testing of the the reference transducer are discussed, and the data acquisition system hardware and software design are described. The calculated and experimental data for the system measurement accuracy are also presented.

Fuel cell system shutdown with anode pressure control

DOEpatents

Clingerman, Bruce J.; Doan, Tien M.; Keskula, Donald H.

2002-01-01

A venting methodology and pressure sensing and vent valving arrangement for monitoring anode bypass valve operating during the normal shutdown of a fuel cell apparatus of the type used in vehicle propulsion systems. During a normal shutdown routine, the pressure differential between the anode inlet and anode outlet is monitored in real time in a period corresponding to the normal closing speed of the anode bypass valve and the pressure differential at the end of the closing cycle of the anode bypass valve is compared to the pressure differential at the beginning of the closing cycle. If the difference in pressure differential at the beginning and end of the anode bypass closing cycle indicates that the anode bypass valve has not properly closed, a system controller switches from a normal shutdown mode to a rapid shutdown mode in which the anode inlet is instantaneously vented by rapid vents.

Real Time Ferrograph Development.

DTIC Science & Technology

1979-11-01

differential temperature of 65 0 C. Since opteo- electronic devices (photodiodes, photoresistors, etc.) have a maximum operating temperature around 85 0 C, it is...flow during the precipitation cycle. This regulator must keep the flow rate constant at any given temperature regardless of the differential pressure...across the sensing head. The pressure regulator achieved this by using the differential pressure across a fixed re;7trictor to move a bellows diaphragm

System for measuring multiphase flow using multiple pressure differentials

DOEpatents

Fincke, James R.

2003-01-01

An improved method and system for measuring a multi-phase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multi-phase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The system for determining the mass flow of the high void fraction fluid flow and the gas flow includes taking into account a pressure drop experienced by the gas phase due to work performed by the gas phase in accelerating the liquid phase.

Validation of Test Methods for Air Leak Rate Verification of Spaceflight Hardware

NASA Technical Reports Server (NTRS)

Oravec, Heather Ann; Daniels, Christopher C.; Mather, Janice L.

2017-01-01

As deep space exploration continues to be the goal of NASAs human spaceflight program, verification of the performance of spaceflight hardware becomes increasingly critical. Suitable test methods for verifying the leak rate of sealing systems are identified in program qualification testing requirements. One acceptable method for verifying the air leak rate of gas pressure seals is the tracer gas leak detector method. In this method, a tracer gas (commonly helium) leaks past the test seal and is transported to the leak detector where the leak rate is quantified. To predict the air leak rate, a conversion factor of helium-to-air is applied depending on the magnitude of the helium flow rate. The conversion factor is based on either the molecular mass ratio or the ratio of the dynamic viscosities. The current work was aimed at validating this approach for permeation-level leak rates using a series of tests with a silicone elastomer O-ring. An established pressure decay method with constant differential pressure was used to evaluate both the air and helium leak rates of the O-ring under similar temperature and pressure conditions. The results from the pressure decay tests showed, for the elastomer O-ring, that neither the molecular flow nor the viscous flow helium-to-air conversion factors were applicable. Leak rate tests were also performed using nitrogen and argon as the test gas. Molecular mass and viscosity based helium-to-test gas conversion factors were applied, but did not correctly predict the measured leak rates of either gas. To further this study, the effect of pressure boundary conditions was investigated. Often, pressure decay leak rate tests are performed at a differential pressure of 101.3 kPa with atmospheric pressure on the downstream side of the test seal. In space applications, the differential pressure is similar, but with vacuum as the downstream pressure. The same O-ring was tested at four unique differential pressures ranging from 34.5 to 137.9 kPa. Up to six combinations of upstream and downstream pressures for each differential pressure were compared. For a given differential pressure, the various combinations of upstream and downstream dry air pressures did not significantly affect the leak rate. As expected, the leak rate of the O-ring increased with increasing differential pressure. The results suggested that the current leak test pressure conditions, used to verify spacecraft sealing systems with elastomer seals, produce accurate values even though the boundary conditions do not model the space application.

Life-history traits and energetic status in relation to vulnerability to angling in an experimentally selected teleost fish.

PubMed

Redpath, Tara D; Cooke, Steven J; Arlinghaus, Robert; Wahl, David H; Philipp, David P

2009-08-01

In recreational fisheries, a correlation has been established between fishing-induced selection pressures and the metabolic traits of individual fish. This study used a population of largemouth bass (Micropterus salmoides) with lines of low vulnerability fish (LVF) and high vulnerability fish (HVF) that were previously established through artificial truncation selection experiments. The main objective was to evaluate if differential vulnerability to angling was correlated with growth, energetics and nutritional condition during the sub-adult stage. Absolute growth rate was found to be between 9% and 17% higher for LVF compared with HVF over a 6-month period in three experimental ponds. The gonadosomatic index in females was lower for LVF compared with HVF in one experimental pond. No significant differences in energy stores (measured using body constituent analysis) were observed between LVF and HVF. In addition, both groups were consuming the same prey items as evidenced by stomach content analysis. The inherent reasons behind differential vulnerability to angling are complex, and selection for these opposing phenotypes appears to select for differing growth rates, although the driving factors remain unclear. These traits are important from a life-history perspective, and alterations to their frequency as a result of fishing-induced selection could alter fish population structure. These findings further emphasize the need to incorporate evolutionary principles into fisheries management activities.

Life-history traits and energetic status in relation to vulnerability to angling in an experimentally selected teleost fish

PubMed Central

Redpath, Tara D; Cooke, Steven J; Arlinghaus, Robert; Wahl, David H; Philipp, David P

2009-01-01

In recreational fisheries, a correlation has been established between fishing-induced selection pressures and the metabolic traits of individual fish. This study used a population of largemouth bass (Micropterus salmoides) with lines of low vulnerability fish (LVF) and high vulnerability fish (HVF) that were previously established through artificial truncation selection experiments. The main objective was to evaluate if differential vulnerability to angling was correlated with growth, energetics and nutritional condition during the sub-adult stage. Absolute growth rate was found to be between 9% and 17% higher for LVF compared with HVF over a 6-month period in three experimental ponds. The gonadosomatic index in females was lower for LVF compared with HVF in one experimental pond. No significant differences in energy stores (measured using body constituent analysis) were observed between LVF and HVF. In addition, both groups were consuming the same prey items as evidenced by stomach content analysis. The inherent reasons behind differential vulnerability to angling are complex, and selection for these opposing phenotypes appears to select for differing growth rates, although the driving factors remain unclear. These traits are important from a life-history perspective, and alterations to their frequency as a result of fishing-induced selection could alter fish population structure. These findings further emphasize the need to incorporate evolutionary principles into fisheries management activities. PMID:25567883

Optimized surgical treatment for normal pressure hydrocephalus: comparison between gravitational and differential pressure valves.

PubMed

Suchorska, B; Kunz, M; Schniepp, R; Jahn, K; Goetz, C; Tonn, J C; Peraud, A

2015-04-01

In idiopathic normal pressure hydrocephalus (NPH) ventriculoperitoneal (VP) shunt insertion is the method of choice to improve cardinal symptoms such as gait disturbance, urge incontinence and/or dementia. With reduced compliance, the brain of the elderly is prone for overdrainage complications. This was especially true with the use of differential pressure valve implantation. The present study compares clinical outcome and complication rates after VP shunt insertion with differential pressure valves in the early years and gravitational valves since 2005. The authors reviewed patients treated at our institution for NPH since 1995. Differential pressure valves were solely used in the initial years, while the treatment regimen changed to gravitational valves in 2005. Clinical improvement/surgical success rates as well as complications were compared between the two groups. Eighty-nine patients were enrolled for the present study. Mean age at the time of surgery was 73.5 ± 6.3 years. Male patients predominated with 73, compared with 16 female patients. Median follow-up time was 28 ± 26 months. Date of last follow-up was 1st October 2013. Forty-nine patients received a gravitational valve, while 40 were treated with differential pressure valves. In the gravitational group a significant improvement was observed after shunt insertion for gait disorder, cognitive impairment and urge incontinence (p < 0.0001, resp. p = 0.004), while a significant change in the differential pressure group was only seen for gait disorder (p = 0.03) but not for cognition or urinary incontinency (p > 0.05). The risk of hygroma as a sign of shunt overdrainage requiring surgical intervention was significantly higher in the differential pressure group (5 versus 0 in the gravitational group). Patients with NPH treated with gravitational valves in the present cohort showed a more profound improvement in their initial symptoms, including gait disorder, cognitive impairment and urinary incontinency without the risk of overdrainage complications requiring surgical intervention when compared with patients who received differential pressure valves in previous years.

Rates of evolution in stress-related genes are associated with habitat preference in two Cardamine lineages

PubMed Central

2012-01-01

Background Elucidating the selective and neutral forces underlying molecular evolution is fundamental to understanding the genetic basis of adaptation. Plants have evolved a suite of adaptive responses to cope with variable environmental conditions, but relatively little is known about which genes are involved in such responses. Here we studied molecular evolution on a genome-wide scale in two species of Cardamine with distinct habitat preferences: C. resedifolia, found at high altitudes, and C. impatiens, found at low altitudes. Our analyses focussed on genes that are involved in stress responses to two factors that differentiate the high- and low-altitude habitats, namely temperature and irradiation. Results High-throughput sequencing was used to obtain gene sequences from C. resedifolia and C. impatiens. Using the available A. thaliana gene sequences and annotation, we identified nearly 3,000 triplets of putative orthologues, including genes involved in cold response, photosynthesis or in general stress responses. By comparing estimated rates of molecular substitution, codon usage, and gene expression in these species with those of Arabidopsis, we were able to evaluate the role of positive and relaxed selection in driving the evolution of Cardamine genes. Our analyses revealed a statistically significant higher rate of molecular substitution in C. resedifolia than in C. impatiens, compatible with more efficient positive selection in the former. Conversely, the genome-wide level of selective pressure is compatible with more relaxed selection in C. impatiens. Moreover, levels of selective pressure were heterogeneous between functional classes and between species, with cold responsive genes evolving particularly fast in C. resedifolia, but not in C. impatiens. Conclusions Overall, our comparative genomic analyses revealed that differences in effective population size might contribute to the differences in the rate of protein evolution and in the levels of selective pressure between the C. impatiens and C. resedifolia lineages. The within-species analyses also revealed evolutionary patterns associated with habitat preference of two Cardamine species. We conclude that the selective pressures associated with the habitats typical of C. resedifolia may have caused the rapid evolution of genes involved in cold response. PMID:22257588

L02 RELIEF AND SHUTOFF VALVE, PRESSURE SENSITIVE CONTROLLER, AND DIFFERENTIAL PRESSURE SWITCH CHECKOUT AND ’END TO END’ CALIBRATION OF THE LOP MISSILE FUEL AND L02 PRESSURE METERS, COMPLEX 576-A,

DTIC Science & Technology

Differential Pressure Switch after the Missile is erected in the tower and connected to Launch Control Circuitry. In addition, a procedure for the ’end to end’ of the L02 and Fuel Tank Pressure Meters is provided. (Author)

Mechanical stimuli differentially control stem cell behavior: morphology, proliferation, and differentiation

PubMed Central

Maul, Timothy M.; Chew, Douglas W.; Nieponice, Alejandro

2011-01-01

Mesenchymal stem cell (MSC) therapy has demonstrated applications in vascular regenerative medicine. Although blood vessels exist in a mechanically dynamic environment, there has been no rigorous, systematic analysis of mechanical stimulation on stem cell differentiation. We hypothesize that mechanical stimuli, relevant to the vasculature, can differentiate MSCs toward smooth muscle (SMCs) and endothelial cells (ECs). This was tested using a unique experimental platform to differentially apply various mechanical stimuli in parallel. Three forces, cyclic stretch, cyclic pressure, and laminar shear stress, were applied independently to mimic several vascular physiologic conditions. Experiments were conducted using subconfluent MSCs for 5 days and demonstrated significant effects on morphology and proliferation depending upon the type, magnitude, frequency, and duration of applied stimulation. We have defined thresholds of cyclic stretch that potentiate SMC protein expression, but did not find EC protein expression under any condition tested. However, a second set of experiments performed at confluence and aimed to elicit the temporal gene expression response of a select magnitude of each stimulus revealed that EC gene expression can be increased with cyclic pressure and shear stress in a cell-contact-dependent manner. Further, these MSCs also appear to express genes from multiple lineages simultaneously which may warrant further investigation into post-transcriptional mechanisms for controlling protein expression. To our knowledge, this is the first systematic examination of the effects of mechanical stimulation on MSCs and has implications for the understanding of stem cell biology, as well as potential bioreactor designs for tissue engineering and cell therapy applications. PMID:21253809

Implementation of a new technology for point detection

NASA Astrophysics Data System (ADS)

Petinarides, John; Griffin, M. Todd; Miller, Ranaan A.; Nazarov, Erkinjon G.; Bashall, Anthony D.

2005-05-01

General Dynamics ATP (GDATP) and Sionex Corporation (Sionex) are carrying out a cooperative development for a handheld chemical agent detector, being called JUNO, which will have lower false positives, higher sensitivity, and improved interference rejection compared with presently available detectors. This enhanced performance is made possible by the use of a new principle of ion separation called Differential Mobility Spectrometry (DMS). The enhanced selectivity is provided by the field tunable nature of the Sionex differential mobility technology (microDMxTM) which forms the analytical heart of the JUNO system and enables fingerprinting of molecules by characterization of the ionized molecular behavior under multiple electric field conditions. This enhanced selectivity is valuable in addressing not only the traditional list of chemical warfare agents (CWA) but also the substantial list of Toxic Industrial Compounds (TICs) and Toxic Industrial Materials (TIMs) which may be released in warfare or terrorist situations. Experimental results showing the ability of the microDMx to reject interferences, detect and resolve live agents are presented. An additional breakthrough in the technology was realized by operating the device at a reduced pressure of around 0.5 atmospheres. This reduced pressure operation resulted in roughly doubling the spectrometers resolution over what has previously been reported [1]. Advances have also been made in power consumption and packaging leading to a device suitable for portable, handheld, applications. Experimental results illustrating the performance of the microDMx technology employed in JUNO are highlighted.

New Hardware for Tethered Balloons,

DTIC Science & Technology

1980-01-01

package contained a differential- pressure switch , and a command receiver. Long wires extended up to the gas valves to actuate them, and a long tube was...similar in appear- ance to the former valve, but does contain batteries, an aneroid- operated switch, and a differential- pressure switch . Design is such...that either the aneroid-operated switch or the differential- pressure switch can be easily removed for checking Or setting in the laboratory. Likewise the

Genetic Variation in the Acorn Barnacle from Allozymes to Population Genomics

PubMed Central

Flight, Patrick A.; Rand, David M.

2012-01-01

Understanding the patterns of genetic variation within and among populations is a central problem in population and evolutionary genetics. We examine this question in the acorn barnacle, Semibalanus balanoides, in which the allozyme loci Mpi and Gpi have been implicated in balancing selection due to varying selective pressures at different spatial scales. We review the patterns of genetic variation at the Mpi locus, compare this to levels of population differentiation at mtDNA and microsatellites, and place these data in the context of genome-wide variation from high-throughput sequencing of population samples spanning the North Atlantic. Despite considerable geographic variation in the patterns of selection at the Mpi allozyme, this locus shows rather low levels of population differentiation at ecological and trans-oceanic scales (FST ∼ 5%). Pooled population sequencing was performed on samples from Rhode Island (RI), Maine (ME), and Southwold, England (UK). Analysis of more than 650 million reads identified approximately 335,000 high-quality SNPs in 19 million base pairs of the S. balanoides genome. Much variation is shared across the Atlantic, but there are significant examples of strong population differentiation among samples from RI, ME, and UK. An FST outlier screen of more than 22,000 contigs provided a genome-wide context for interpretation of earlier studies on allozymes, mtDNA, and microsatellites. FST values for allozymes, mtDNA and microsatellites are close to the genome-wide average for random SNPs, with the exception of the trans-Atlantic FST for mtDNA. The majority of FST outliers were unique between individual pairs of populations, but some genes show shared patterns of excess differentiation. These data indicate that gene flow is high, that selection is strong on a subset of genes, and that a variety of genes are experiencing diversifying selection at large spatial scales. This survey of polymorphism in S. balanoides provides a number of genomic tools that promise to make this a powerful model for ecological genomics of the rocky intertidal. PMID:22767487

Prey from the eyes of predators: Color discriminability of aposematic and mimetic butterflies from an avian visual perspective.

PubMed

Su, Shiyu; Lim, Matthew; Kunte, Krushnamegh

2015-11-01

Predation exerts strong selection on mimetic butterfly wing color patterns, which also serve other functions such as sexual selection. Therefore, specific selection pressures may affect the sexes and signal components differentially. We tested three predictions about the evolution of mimetic resemblance by comparing wing coloration of aposematic butterflies and their Batesian mimics: (a) females gain greater mimetic advantage than males and therefore are better mimics, (b) due to intersexual genetic correlations, sexually monomorphic mimics are better mimics than female-limited mimics, and (c) mimetic resemblance is better on the dorsal wing surface that is visible to predators in flight. Using a physiological model of avian color vision, we quantified mimetic resemblance from predators' perspective, which showed that female butterflies were better mimics than males. Mimetic resemblance in female-limited mimics was comparable to that in sexually monomorphic mimics, suggesting that intersexual genetic correlations did not constrain adaptive response to selection for female-limited mimicry. Mimetic resemblance on the ventral wing surface was better than that on the dorsal wing surface, implying stronger natural and sexual selection on ventral and dorsal surfaces, respectively. These results suggest that mimetic resemblance in butterfly mimicry rings has evolved under various selective pressures acting in a sex- and wing surface-specific manner. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

Evidence of Adaptive Evolution and Relaxed Constraints in Sex-Biased Genes of South American and West Indies Fruit Flies (Diptera: Tephritidae).

PubMed

Congrains, Carlos; Campanini, Emeline B; Torres, Felipe R; Rezende, Víctor B; Nakamura, Aline M; de Oliveira, Janaína L; Lima, André L A; Chahad-Ehlers, Samira; Sobrinho, Iderval S; de Brito, Reinaldo A

2018-01-01

Several studies have demonstrated that genes differentially expressed between sexes (sex-biased genes) tend to evolve faster than unbiased genes, particularly in males. The reason for this accelerated evolution is not clear, but several explanations have involved adaptive and nonadaptive mechanisms. Furthermore, the differences of sex-biased expression patterns of closely related species are also little explored out of Drosophila. To address the evolutionary processes involved with sex-biased expression in species with incipient differentiation, we analyzed male and female transcriptomes of Anastrepha fraterculus and Anastrepha obliqua, a pair of species that have diverged recently, likely in the presence of gene flow. Using these data, we inferred differentiation indexes and evolutionary rates and tested for signals of selection in thousands of genes expressed in head and reproductive transcriptomes from both species. Our results indicate that sex-biased and reproductive-biased genes evolve faster than unbiased genes in both species, which is due to both adaptive pressure and relaxed constraints. Furthermore, among male-biased genes evolving under positive selection, we identified some related to sexual functions such as courtship behavior and fertility. These findings suggest that sex-biased genes may have played important roles in the establishment of reproductive isolation between these species, due to a combination of selection and drift, and unveil a plethora of genetic markers useful for more studies in these species and their differentiation. © The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

Transcriptome analysis of post-hatch breast muscle in legacy and modern broiler chickens reveals enrichment of several regulators of myogenic growth.

PubMed

Davis, Richard V N; Lamont, Susan J; Rothschild, Max F; Persia, Michael E; Ashwell, Chris M; Schmidt, Carl J

2015-01-01

Agriculture provides excellent model systems for understanding how selective pressure, as applied by humans, can affect the genomes of plants and animals. One such system is modern poultry breeding in which intensive genetic selection has been applied for meat production in the domesticated chicken. As a result, modern meat-type chickens (broilers) exhibit enhanced growth, especially of the skeletal muscle, relative to their legacy counterparts. Comparative studies of modern and legacy broiler chickens provide an opportunity to identify genes and pathways affected by this human-directed evolution. This study used RNA-seq to compare the transcriptomes of a modern and a legacy broiler line to identify differentially enriched genes in the breast muscle at days 6 and 21 post-hatch. Among the 15,945 genes analyzed, 10,841 were expressed at greater than 0.1 RPKM. At day 6 post-hatch 189 genes, including several regulators of myogenic growth and development, were differentially enriched between the two lines. The transcriptional profiles between lines at day 21 post-hatch identify 193 genes differentially enriched and still include genes associated with myogenic growth. This study identified differentially enriched genes that regulate myogenic growth and differentiation between the modern and legacy broiler lines. Specifically, differences in the ratios of several positive (IGF1, IGF1R, WFIKKN2) and negative (MSTN, ACE) myogenic growth regulators may help explain the differences underlying the enhanced growth characteristics of the modern broilers.

Differentiation and specialization in the California hospital industry 1983 to 1988.

PubMed

Zwanziger, J; Melnick, G A; Simonson, L

1996-04-01

This article examines changes in the service mix of California hospitals as part of their response to shifts in the system of reimbursement between 1983 and 1988. The Hospital Discharge Data Set and the Annual Hospital Disclosure Report produced by California Office of Statewide Health Planning and Development were used in this study. Characteristics of inpatient hospital services in California before and after the introduction of new reimbursement mechanisms (including the Medicare Prospective Payment System [PPS] and the growth of selective contracting plans) were compared. The factors that influence two measures of hospital service mix, one focusing on specialization and the other on differentiation, were studied. The factors included hospital characteristics and changes in hospital reimbursement. Variables describing a hospital's service mix and the level in its market were constructed from data in the annual discharge abstracts. Data pertaining to average hospital costs and reimbursements under the Medicare PPS were drawn from a file containing a 20% sample of hospital stay records for the year of PPS. Other hospital data, such as ownership and bed size, were taken from the California Annual Disclosure Report data set. The results indicate that completion among hospitals tended to increase differentiation whereas higher financial PPS pressure is associated with increased specialization. Hospitals tend to adopt some high visibility services offered by their competitors while filling market niches selectively overall. It also appears that the cost savings expected for specialization may prevail only for narrowly defined services. Study of subsequent data sets should show whether the cost containment strategies used by the hospitals to achieve these results have been maintained over a period of sustained financial pressure.

Seafloor Pressure Array Studies at Ultra-Low Frequencies

DTIC Science & Technology

1991-01-01

broadband instrument design and deployment. In order to measure broadband noise routinely, a low frequency pressure gauge designed for deep ocean...below the microseism band (Moore et al, 1981). A differential pressure gauge , developed for low frequency recordings by Cox et al (1984) and sensitive to...design differential pressure gauge (Cox et al, 1984) with a sensitivity -3- ULF Seafloor Pressure Array Studies range of 0.01-5 Hz. The high

Correlates of Protective Cellular Immunity Revealed by Analysis of Population-Level Immune Escape Pathways in HIV-1

PubMed Central

Brumme, Chanson J.; Martin, Eric; Listgarten, Jennifer; Brockman, Mark A.; Le, Anh Q.; Chui, Celia K. S.; Cotton, Laura A.; Knapp, David J. H. F.; Riddler, Sharon A.; Haubrich, Richard; Nelson, George; Pfeifer, Nico; DeZiel, Charles E.; Heckerman, David; Apps, Richard; Carrington, Mary; Mallal, Simon; Harrigan, P. Richard; John, Mina

2012-01-01

HLA class I-associated polymorphisms identified at the population level mark viral sites under immune pressure by individual HLA alleles. As such, analysis of their distribution, frequency, location, statistical strength, sequence conservation, and other properties offers a unique perspective from which to identify correlates of protective cellular immunity. We analyzed HLA-associated HIV-1 subtype B polymorphisms in 1,888 treatment-naïve, chronically infected individuals using phylogenetically informed methods and identified characteristics of HLA-associated immune pressures that differentiate protective and nonprotective alleles. Over 2,100 HLA-associated HIV-1 polymorphisms were identified, approximately one-third of which occurred inside or within 3 residues of an optimally defined cytotoxic T-lymphocyte (CTL) epitope. Differential CTL escape patterns between closely related HLA alleles were common and increased with greater evolutionary distance between allele group members. Among 9-mer epitopes, mutations at HLA-specific anchor residues represented the most frequently detected escape type: these occurred nearly 2-fold more frequently than expected by chance and were computationally predicted to reduce peptide-HLA binding nearly 10-fold on average. Characteristics associated with protective HLA alleles (defined using hazard ratios for progression to AIDS from natural history cohorts) included the potential to mount broad immune selection pressures across all HIV-1 proteins except Nef, the tendency to drive multisite and/or anchor residue escape mutations within known CTL epitopes, and the ability to strongly select mutations in conserved regions within HIV's structural and functional proteins. Thus, the factors defining protective cellular immune responses may be more complex than simply targeting conserved viral regions. The results provide new information to guide vaccine design and immunogenicity studies. PMID:23055555

Method for solvent extraction with near-equal density solutions

DOEpatents

Birdwell, Joseph F.; Randolph, John D.; Singh, S. Paul

2001-01-01

Disclosed is a modified centrifugal contactor for separating solutions of near equal density. The modified contactor has a pressure differential establishing means that allows the application of a pressure differential across fluid in the rotor of the contactor. The pressure differential is such that it causes the boundary between solutions of near-equal density to shift, thereby facilitating separation of the phases. Also disclosed is a method of separating solutions of near-equal density.

14 CFR 23.365 - Pressurized cabin loads.

Code of Federal Regulations, 2011 CFR

2011-01-01

... landing. (d) The airplane structure must be strong enough to withstand the pressure differential loads... AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND COMMUTER CATEGORY AIRPLANES Structure Flight Loads § 23... structure must be strong enough to withstand the flight loads combined with pressure differential loads from...

Reduction of the pectoral spine and girdle in domesticated Channel catfish is likely caused by changes in selection pressure.

PubMed

Fine, Michael L; Lahiri, Shweta; Sullivan, Amanda D H; Mayo, Mark; Newton, Scott H; Sismour, Edward N

2014-07-01

Locked pectoral spines of the Channel Catfish Ictalurus punctatus more than double the fish's width and complicate ingestion by gape-limited predators. The spine mates with the pectoral girdle, a robust structure that anchors the spine. This study demonstrates that both spine and girdle exhibit negative allometric growth and that pectoral spines and girdles are lighter in domesticated than in wild Channel Catfish. This finding could be explained by changes in selection pressure for spine growth during domestication or by an epigenetic effect in which exposure to predators in wild fish stimulates pectoral growth. We tested the epigenetic hypothesis by exposing domesticated Channel Catfish fingerlings to Largemouth Bass Micropterus salmoides predators for 13 weeks. Spines and girdles grow isometrically in the fingerlings, and regression analysis indicates no difference in proportional pectoral growth between control and predator-exposed fish. Therefore a change in selection pressure likely accounts for smaller pectoral growth in domesticated Channel Catfish. Decreasing spine growth in older fish suggests anti-predator functions are most important in smaller fish. Additionally, growth of the appendicular and axial skeleton is controlled differentially, and mechanical properties of the spine and not just its length are an important component of this defensive adaptation. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

Stress remagnetization in pyrrhotite-calcite synthetic aggregates

NASA Astrophysics Data System (ADS)

Robion, Philippe; Borradaile, Graham J.

2001-01-01

Stress-induced remagnetization has been applied to multidomain pyrrhotite-calcite synthetic aggregates in a triaxial rig. Experimental deformation used 150MPa confining pressure, a constant strain rate of 10-5 s-1 and applied differential stresses of up to 70MPa. New components of magnetization, parallel to the direction of the pressure vessel field, were added to the pre-deformational magnetization. The intensity of remagnetization (M'-M0) increases with the intensity of the applied differential stress and affects the coercivity fraction below 15mT. Bulk shortening is less than 8 per cent, thus grain rotation cannot explain selective remagnetization of the low-coercivity fraction. Remagnetization is thus attributed to deformational viscous remanent magnetization (DVRM). It is observed that high-coercivity (>15mT) grains do not remagnetize. There is, however, slight progressive rotation of pre-deformational magnetization with increasing strain up to 8 per cent of bulk shortening. The lack of piezoremanent magnetization in the high-coercivity range may be due to defects introduced in pyrrhotite during sample preparation. Experiments using synthetic pyrrhotite, expected to show low dislocation densities, would be necessary to test this effect.

Application of a methodology for categorizing and differentiating urban soundscapes using acoustical descriptors and semantic-differential attributes.

PubMed

Torija, Antonio J; Ruiz, Diego P; Ramos-Ridao, A F

2013-07-01

A subjective and physical categorization of an ambient sound is the first step to evaluate the soundscape and provides a basis for designing or adapting this ambient sound to match people's expectations. For this reason, the main goal of this work is to develop a categorization and differentiation analysis of soundscapes on the basis of acoustical and perceptual variables. A hierarchical cluster analysis, using 15 semantic-differential attributes and acoustical descriptors to include an equivalent sound-pressure level, maximum-minimum sound-pressure level, impulsiveness of the sound-pressure level, sound-pressure level time course, and spectral composition, was conducted to classify soundscapes into different typologies. This analysis identified 15 different soundscape typologies. Furthermore, based on a discriminant analysis the acoustical descriptors, the crest factor (impulsiveness of the sound-pressure level), and the sound level at 125 Hz were found to be the acoustical variables with the highest impact in the differentiation of the recognized types of soundscapes. Finally, to determine how the different soundscape typologies differed from each other, both subjectively and acoustically, a study was performed.

RNA-Seq transcriptome analysis of Amaranthus palmeri with differential tolerance to glufosinate herbicide

PubMed Central

Salas-Perez, Reiofeli A.; Saski, Christopher A.; Noorai, Rooksana E.; Srivastava, Subodh K.; Lawton-Rauh, Amy L.; Nichols, Robert L.

2018-01-01

Amaranthus palmeri (Amaranthaceae) is a noxious weed in several agroecosystems and in some cases seriously threatens the sustainability of crop production in North America. Glyphosate-resistant Amaranthus species are widespread, prompting the use of alternatives to glyphosate such as glufosinate, in conjunction with glufosinate-resistant crop cultivars, to help control glyphosate-resistant weeds. An experiment was conducted to analyze the transcriptome of A. palmeri plants that survived exposure to 0.55 kg ha-1 glufosinate. Since there was no record of glufosinate use at the collection site, survival of plants within the population are likely due to genetic expression that pre-dates selection; in the formal parlance of weed science this is described as natural tolerance. Leaf tissues from glufosinate-treated and non-treated seedlings were harvested 24 h after treatment (HAT) for RNA-Seq analysis. Global gene expression was measured using Illumina DNA sequence reads from non-treated and treated surviving (presumably tolerant, T) and susceptible (S) plants. The same plants were used to determine the mechanisms conferring differential tolerance to glufosinate. The S plants accumulated twice as much ammonia as did the T plants, 24 HAT. The relative copy number of the glufosinate target gene GS2 did not differ between T and S plants, with 1 to 3 GS2 copies in both biotypes. A reference cDNA transcriptome consisting of 72,780 contigs was assembled, with 65,282 sequences putatively annotated. Sequences of GS2 from the transcriptome assembly did not have polymorphisms unique to the tolerant plants. Five hundred sixty-seven genes were differentially expressed between treated T and S plants. Of the upregulated genes in treated T plants, 210 were more highly induced than were the upregulated genes in the treated S plants. Glufosinate-tolerant plants had greater induction of ABC transporter, glutathione S-transferase (GST), NAC transcription factor, nitronate monooxygenase (NMO), chitin elicitor receptor kinase (CERK1), heat shock protein 83, ethylene transcription factor, heat stress transcription factor, NADH-ubiquinone oxidoreductase, ABA 8’-hydroxylase, and cytochrome P450 genes (CYP72A, CYP94A1). Seven candidate genes were selected for validation using quantitative real time-PCR. While GST was upregulated in treated tolerant plants in at least one population, CYP72A219 was consistently highly expressed in all treated tolerant biotypes. These genes are candidates for contributing tolerance to glufosinate. Taken together, these results show that differential induction of stress-protection genes in a population can enable some individuals to survive herbicide application. Elevated expression of detoxification-related genes can get fixed in a population with sustained selection pressure, leading to evolution of resistance. Alternatively, sustained selection pressure could select for mutation(s) in the GS2 gene with the same consequence. PMID:29672568

Electron beam enhanced surface modification for making highly resolved structures

DOEpatents

Pitts, John R.

1986-01-01

A method for forming high resolution submicron structures on a substrate is provided by direct writing with a submicron electron beam in a partial pressure of a selected gas phase characterized by the ability to dissociate under the beam into a stable gaseous leaving group and a reactant fragment that combines with the substrate material under beam energy to form at least a surface compound. Variations of the method provide semiconductor device regions on doped silicon substrates, interconnect lines between active sites, three dimensional electronic chip structures, electron beam and optical read mass storage devices that may include color differentiated data areas, and resist areas for use with selective etching techniques.

Electron beam enhanced surface modification for making highly resolved structures

DOEpatents

Pitts, J.R.

1984-10-10

A method for forming high resolution submicron structures on a substrate is provided by direct writing with a submicron electron beam in a partial pressure of a selected gas phase characterized by the ability to dissociate under the beam into a stable gaseous leaving group and a reactant fragment that combines with the substrate material under beam energy to form at least a surface compound. Variations of the method provide semiconductor device regions on doped silicon substrates, interconnect lines between active sites, three dimensional electronic chip structures, electron beam and optical read mass storage devices that may include color differentiated data areas, and resist areas for use with selective etching techniques.

Flowmeter evaluation for on-orbit operations

NASA Technical Reports Server (NTRS)

Baird, R. S.

1988-01-01

Various flowmetering concepts were flow tested to characterize the relative capabilities and limitations for on-orbit fluid-transfer operations. Performance results and basic operating principles of each flowmetering concept tested are summarized, and basic considerations required to select the best flowmeter(s) for fluid system application are discussed. Concepts tested were clamp-on ultrasonic, area averaging ultrasonic, offset ultrasonic, coriolis mass, vortex shedding, universal venturi tube, turbine, bearingless turbine, turbine/turbine differential-pressure hybrid, dragbody, and dragbody/turbine hybrid flowmeters. Fluid system flowmeter selection considerations discussed are flowmeter performance, fluid operating conditions, systems operating environments, flowmeter packaging, flowmeter maintenance, and flowmeter technology. No one flowmetering concept tested was shown to be best for all on-orbit fluid systems.

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.

- and Frequency-Domain Signatures of Velocity Changing Collisions in Sub-Doppler Saturation Spectra and Pressure Broadening

NASA Astrophysics Data System (ADS)

Hall, Gregory; Xu, Hong; Forthomme, Damien; Dagdigian, Paul; Sears, Trevor

2017-06-01

We have combined experimental and theoretical approaches to the competition between elastic and inelastic collisions of CN radicals with Ar, and how this competition influences time-resolved saturation spectra. Experimentally, we have measured transient, two-color sub-Doppler saturation spectra of CN radicals with an amplitude chopped saturation laser tuned to selected Doppler offsets within rotational lines of the A-X (2-0) band, while scanning a frequency modulated probe laser across the hyperfine-resolved saturation features of corresponding rotational lines of the A-X (1-0) band. A steady-state depletion spectrum includes off-resonant contributions ascribed to velocity diffusion, and the saturation recovery rates depend on the sub-Doppler detuning. The experimental results are compared with Monte Carlo solutions to the Boltzmann equation for the collisional evolution of the velocity distributions of CN radicals, combined with a pressure-dependent and speed-dependent lifetime broadening. Velocity changing collisions are included by appropriately sampling the energy resolved differential cross sections for elastic scattering of selected rotational states of CN (X). The velocity space diffusion of Doppler tagged molecules proceeds through a series of small-angle scattering events, eventually terminating in an inelastic collision that removes the molecule from the coherently driven ensemble of interest. Collision energy-dependent total cross sections and differential cross sections for elastic scattering of selected CN rotational states with Ar were computed with Hibridon quantum scattering calculations, and used for sampling in the Monte Carlo modeling. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences and Biosciences within the Office of Basic Energy Sciences.

Optical zero-differential pressure switch and its evaluation in a multiple pressure measuring system

NASA Technical Reports Server (NTRS)

Powell, J. A.

1977-01-01

The design of a clamped-diaphragm pressure switch is described in which diaphragm motion is detected by a simple fiber-optic displacement sensor. The switch was evaluated in a pressure measurement system where it detected the zero crossing of the differential pressure between a static test pressure and a tank pressure that was periodically ramped from near zero to fullscale gage pressure. With a ramping frequency of 1 hertz and a full-scale tank pressure of 69 N/sq cm gage (100 psig), the switch delay was as long as 2 milliseconds. Pressure measurement accuracies were 0.25 to 0.75 percent of full scale. Factors affecting switch performance are also discussed.

Differential retention of metabolic genes following whole-genome duplication.

PubMed

Gout, Jean-François; Duret, Laurent; Kahn, Daniel

2009-05-01

Classical studies in Metabolic Control Theory have shown that metabolic fluxes usually exhibit little sensitivity to changes in individual enzyme activity, yet remain sensitive to global changes of all enzymes in a pathway. Therefore, little selective pressure is expected on the dosage or expression of individual metabolic genes, yet entire pathways should still be constrained. However, a direct estimate of this selective pressure had not been evaluated. Whole-genome duplications (WGDs) offer a good opportunity to address this question by analyzing the fates of metabolic genes during the massive gene losses that follow. Here, we take advantage of the successive rounds of WGD that occurred in the Paramecium lineage. We show that metabolic genes exhibit different gene retention patterns than nonmetabolic genes. Contrary to what was expected for individual genes, metabolic genes appeared more retained than other genes after the recent WGD, which was best explained by selection for gene expression operating on entire pathways. Metabolic genes also tend to be less retained when present at high copy number before WGD, contrary to other genes that show a positive correlation between gene retention and preduplication copy number. This is rationalized on the basis of the classical concave relationship relating metabolic fluxes with enzyme expression.

BMD Loci Contribute to Ethnic and Developmental Differences in Skeletal Fragility across Populations: Assessment of Evolutionary Selection Pressures

PubMed Central

Medina-Gómez, Carolina; Chesi, Alessandra; Heppe, Denise H.M.; Zemel, Babette S.; Yin, Jia-Lian; Kalkwarf, Heidi J.; Hofman, Albert; Lappe, Joan M.; Kelly, Andrea; Kayser, Manfred; Oberfield, Sharon E.; Gilsanz, Vicente; Uitterlinden, André G.; Shepherd, John A.; Jaddoe, Vincent W.V.; Grant, Struan F.A.; Lao, Oscar; Rivadeneira, Fernando

2015-01-01

Bone mineral density (BMD) is a highly heritable trait used both for the diagnosis of osteoporosis in adults and to assess bone health in children. Ethnic differences in BMD have been documented, with markedly higher levels in individuals of African descent, which partially explain disparity in osteoporosis risk across populations. To date, 63 independent genetic variants have been associated with BMD in adults of Northern-European ancestry. Here, we demonstrate that at least 61 of these variants are predictive of BMD early in life by studying their compound effect within two multiethnic pediatric cohorts. Furthermore, we show that within these cohorts and across populations worldwide the frequency of those alleles associated with increased BMD is systematically elevated in individuals of Sub-Saharan African ancestry. The amount of differentiation in the BMD genetic scores among Sub-Saharan and non-Sub-Saharan populations together with neutrality tests, suggest that these allelic differences are compatible with the hypothesis of selective pressures acting on the genetic determinants of BMD. These findings constitute an explorative contribution to the role of selection on ethnic BMD differences and likely a new example of polygenic adaptation acting on a human trait. PMID:26226985

On Small Disturbance Ascent Vent Behavior

NASA Technical Reports Server (NTRS)

Woronowicz, Michael

2015-01-01

As a spacecraft undergoes ascent in a launch vehicle, its ambient pressure environment transitions from one atmosphere to high vacuum in a matter of a few minutes. Venting of internal cavities is necessary to prevent the buildup of pressure differentials across cavity walls. These pressure differentials are often restricted to low levels to prevent violation of container integrity. Such vents usually consist of fixed orifices, ducts, or combinations of both. Duct conductance behavior is fundamentally different from that for orifices in pressure driven flows governing the launch vehicle ascent depressurization environment. Duct conductance is governed by the average pressure across its length, while orifice conductance is dictated by a pressure ratio. Hence, one cannot define a valid equivalent orifice for a given duct across a range of pressure levels. This presentation discusses development of expressions for these two types of vent elements in the limit of small pressure differentials, explores conditions for their validity, and compares their features regarding ascent depressurization performance.

Heritability and quantitative genetic divergence of serotiny, a fire-persistence plant trait

PubMed Central

Hernández-Serrano, Ana; Verdú, Miguel; Santos-del-Blanco, Luís; Climent, José; González-Martínez, Santiago C.; Pausas, Juli G.

2014-01-01

Background and Aims Although it is well known that fire acts as a selective pressure shaping plant phenotypes, there are no quantitative estimates of the heritability of any trait related to plant persistence under recurrent fires, such as serotiny. In this study, the heritability of serotiny in Pinus halepensis is calculated, and an evaluation is made as to whether fire has left a selection signature on the level of serotiny among populations by comparing the genetic divergence of serotiny with the expected divergence of neutral molecular markers (QST–FST comparison). Methods A common garden of P. halepensis was used, located in inland Spain and composed of 145 open-pollinated families from 29 provenances covering the entire natural range of P. halepensis in the Iberian Peninsula and Balearic Islands. Narrow-sense heritability (h2) and quantitative genetic differentiation among populations for serotiny (QST) were estimated by means of an ‘animal model’ fitted by Bayesian inference. In order to determine whether genetic differentiation for serotiny is the result of differential natural selection, QST estimates for serotiny were compared with FST estimates obtained from allozyme data. Finally, a test was made of whether levels of serotiny in the different provenances were related to different fire regimes, using summer rainfall as a proxy for fire regime in each provenance. Key Results Serotiny showed a significant narrow-sense heritability (h2) of 0·20 (credible interval 0·09–0·40). Quantitative genetic differentiation among provenances for serotiny (QST = 0·44) was significantly higher than expected under a neutral process (FST = 0·12), suggesting adaptive differentiation. A significant negative relationship was found between the serotiny level of trees in the common garden and summer rainfall of their provenance sites. Conclusions Serotiny is a heritable trait in P. halepensis, and selection acts on it, giving rise to contrasting serotiny levels among populations depending on the fire regime, and supporting the role of fire in generating genetic divergence for adaptive traits. PMID:25008363

Spacecraft compartment venting

NASA Astrophysics Data System (ADS)

Scialdone, John J.

1998-10-01

At various times, concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

Spacecraft Compartment Venting

NASA Technical Reports Server (NTRS)

Scialdone, John J.

1998-01-01

At various time concerns have been expressed that rapid decompressions of compartments of gas pockets and thermal blankets during spacecraft launches may have caused pressure differentials across their walls sufficient to cause minor structural failures, separations of adhesively-joined parts, ballooning, and flapping of blankets. This paper presents a close form equation expressing the expected pressure differentials across the walls of a compartment as a function of the external to the volume pressure drops, the pressure at which the rates occur and the vent capability of the compartment. The pressure profiles measured inside the shrouds of several spacecraft propelled by several vehicles and some profiles obtained from ground vacuum systems have been included. The equation can be used to design the appropriate vent, which will preclude excessive pressure differentials. Precautions and needed approaches for the evaluations of the expected pressures have been indicated. Methods to make a rapid assessment of the response of the compartment to rapid external pressure drops have been discussed. These are based on the evaluation of the compartment vent flow conductance, the volume and the length of time during which the rapid pressure drop occurs.

The Effect of Superior Semicircular Canal Dehiscence on Intracochlear Sound Pressures

NASA Astrophysics Data System (ADS)

Nakajima, Hideko Heidi; Pisano, Dominic V.; Merchant, Saumil N.; Rosowski, John J.

2011-11-01

Semicircular canal dehiscence (SCD) is a pathological opening in the bony wall of the inner ear that can result in conductive hearing loss. The hearing loss is variable across patients, and the precise mechanism and source of variability is not fully understood. We use intracochlear sound pressure measurements in cadaveric preparations to study the effects of SCD size. Simultaneous measurement of basal intracochlear sound pressures in scala vestibuli (SV) and scala tympani (ST) quantifies the complex differential pressure across the cochlear partition, the stimulus that excites the partition. Sound-induced pressures in SV and ST, as well as stapes velocity and ear-canal pressure are measured simultaneously for various sizes of SCD followed by SCD patching. At low frequencies (<600 Hz) our results show that SCD decreases the pressure in both SV and ST, as well as differential pressure, and these effects become more pronounced as dehiscence size is increased. For frequencies above 1 kHz, the smallest pinpoint dehiscence can have the larger effect on the differential pressure in some ears. These effects due to SCD are reversible by patching the dehiscence.

Pressure compensated flow control valve

DOEpatents

Minteer, Daniel J.

1999-01-01

The invention is an air flow control valve which is capable of maintaining a constant flow at the outlet despite changes in the inlet or outlet pressure. The device consists of a shell assembly with an inlet chamber and outlet chamber separated by a separation plate. The chambers are connected by an orifice. Also located within the inlet chamber is a port controller assembly. The port controller assembly consists of a differential pressure plate and port cap affixed thereon. The cap is able to slide in and out of the orifice separating the inlet and outlet chambers. When the pressure differential is sufficient, the differential pressure plate rises or falls to maintain a constant air flow. Movement of the port controller assembly does not require the use of seals, diaphragms, tight tolerances, bushings, bearings, hinges, guides, or lubricants.

Controlled differential pressure system for an enhanced fluid blending apparatus

DOEpatents

Hallman, Jr., Russell Louis

2009-02-24

A system and method for producing a controlled blend of two or more fluids. Thermally-induced permeation through a permeable tube is used to mix a first fluid from outside the tube with a second fluid flowing through the tube. Mixture ratios may be controlled by adjusting the temperature of the first fluid or by adjusting the pressure drop through the permeable tube. The combination of a back pressure control valve and a differential regulator is used to control the output pressure of the blended fluid. The combination of the back pressure control valve and differential regulator provides superior flow control of the second dry gas. A valve manifold system may be used to mix multiple fluids, and to adjust the volume of blended fluid produced, and to further modify the mixture ratio.

Hydrostatic pressure promotes the proliferation and osteogenic/chondrogenic differentiation of mesenchymal stem cells: The roles of RhoA and Rac1.

PubMed

Zhao, Yin-Hua; Lv, Xin; Liu, Yan-Li; Zhao, Ying; Li, Qiang; Chen, Yong-Jin; Zhang, Min

2015-05-01

Our previous studies have shown that hydrostatic pressure can serve as an active regulator for bone marrow mesenchymal stem cells (BMSCs). The current work further investigates the roles of cytoskeletal regulatory proteins Ras homolog gene family member A (RhoA) and Ras-related C3 botulinum toxin substrate 1 (Rac1) in hydrostatic pressure-related effects on BMSCs. Flow cytometry assays showed that the hydrostatic pressure promoted cell cycle initiation in a RhoA- and Rac1-dependent manner. Furthermore, fluorescence assays confirmed that RhoA played a positive and Rac1 displayed a negative role in the hydrostatic pressure-induced F-actin stress fiber assembly. Western blots suggested that RhoA and Rac1 play central roles in the pressure-inhibited ERK phosphorylation, and Rac1 but not RhoA was involved in the pressure-promoted JNK phosphorylation. Finally, real-time polymerase chain reaction (PCR) experiments showed that pressure promoted the expression of osteogenic marker genes in BMSCs at an early stage of osteogenic differentiation through the up-regulation of RhoA activity. Additionally, the PCR results showed that pressure enhanced the expression of chondrogenic marker genes in BMSCs during chondrogenic differentiation via the up-regulation of Rac1 activity. Collectively, our results suggested that RhoA and Rac1 are critical to the pressure-induced proliferation and differentiation, the stress fiber assembly, and MAPK activation in BMSCs. Copyright © 2015. Published by Elsevier B.V.

Design of Novel FBG-Based Sensor of Differential Pressure with Magnetic Transfer.

PubMed

Lyu, Guohui; Che, Guohang; Li, Junqing; Jiang, Xu; Wang, Keda; Han, Yueqiang; Gao, Laixu

2017-02-15

In this paper, a differential pressure sensor with magnetic transfer is proposed, in which the non-electric measurement based on the fiber Bragg grating (FBG) with the position limiting mechanism is implemented without the direct contact of the sensing unit with the measuring fluid. The test shows that the designed sensor is effective for measuring differential pressure in the range of 0~10 kPa with a sensitivity of 0.0112 nm/kPa, which can be used in environments with high temperature, strong corrosion and high overload measurements.

A flowing atmospheric pressure afterglow as an ion source coupled to a differential mobility analyzer for volatile organic compound detection.

PubMed

Bouza, Marcos; Orejas, Jaime; López-Vidal, Silvia; Pisonero, Jorge; Bordel, Nerea; Pereiro, Rosario; Sanz-Medel, Alfredo

2016-05-23

Atmospheric pressure glow discharges have been widely used in the last decade as ion sources in ambient mass spectrometry analyses. Here, an in-house flowing atmospheric pressure afterglow (FAPA) has been developed as an alternative ion source for differential mobility analysis (DMA). The discharge source parameters (inter-electrode distance, current and helium flow rate) determining the atmospheric plasma characteristics have been optimized in terms of DMA spectral simplicity with the highest achievable sensitivity while keeping an adequate plasma stability and so the FAPA working conditions finally selected were: 35 mA, 1 L min(-1) of He and an inter-electrode distance of 8 mm. Room temperature in the DMA proved to be adequate for the coupling and chemical analysis with the FAPA source. Positive and negative ions for different volatile organic compounds were tested and analysed by FAPA-DMA using a Faraday cup as a detector and proper operation in both modes was possible (without changes in FAPA operational parameters). The FAPA ionization source showed simpler ion mobility spectra with narrower peaks and a better, or similar, sensitivity than conventional UV-photoionization for DMA analysis in positive mode. Particularly, the negative mode proved to be a promising field of further research for the FAPA ion source coupled to ion mobility, clearly competitive with other more conventional plasmas such as corona discharge.

The Effect of Superior Semicircular Canal Dehiscence on Intracochlear Sound Pressures

PubMed Central

Pisano, Dominic V.; Niesten, Marlien E.F.; Merchant, Saumil N.; Nakajima, Hideko Heidi

2013-01-01

Semicircular canal dehiscence (SCD) is a pathological opening in the bony wall of the inner ear that can result in conductive hearing loss. The hearing loss is variable across patients, and the precise mechanism and source of variability are not fully understood. Simultaneous measurements of basal intracochlear sound pressures in scala vestibuli (SV) and scala tympani (ST) enable quantification of the differential pressure across the cochlear partition, the stimulus that excites the cochlear partition. We used intracochlear sound pressure measurements in cadaveric preparations to study the effects of SCD size. Sound-induced pressures in SV and ST, as well as stapes velocity and ear-canal pressure were measured simultaneously for various sizes of SCD followed by SCD patching. Our results showed that at low frequencies (<600 Hz), SCD decreased the pressure in both SV and ST, as well as differential pressure, and these effects became more pronounced as dehiscence size was increased. Near 100 Hz, SV decreased about 10 dB for a 0.5 mm dehiscence and 20 dB for a 2 mm dehiscence, while ST decreased about 8 dB for a 0.5 mm dehiscence and 18 dB for a 2mm dehiscence. Differential pressure decreased about 10 dB for a 0.5 mm dehiscence and about 20 dB for a 2 mm dehiscense at 100 Hz. In some ears, for frequencies above 1 kHz, the smallest pinpoint dehiscence had bigger effects on the differential pressure (10 dB decrease) than larger dehiscenses (less than 10 dB decrease), suggesting larger hearing losses in this frequency range. These effects due to SCD were reversible by patching the dehiscence. We also showed that under certain circumstances such as SCD, stapes velocity is not related to how the ear can transduce sound across the cochlear partition because it is not directly related to the differential pressure, emphasizing that certain pathologies cannot be fully assessed by measurements such as stapes velocity. PMID:22814034

A program to evaluate a control system based on feedback of aerodynamic pressure differentials, part 1

NASA Technical Reports Server (NTRS)

Hrabak, R. R.; Levy, D. W.; Finn, P.; Roskam, J.

1981-01-01

The use of pressure differentials in a flight control system was evaluated. The pressure profile around the test surface was determined using two techniques: (1) windtunnel data (actual); and (2) NASA/Langley Single Element Airfoil Computer Program (theoretical). The system designed to evaluate the concept of using pressure differentials is composed of a sensor drive and power amplifiers, actuator, position potentiometer, and a control surface. The characteristics (both desired and actual) of the system and each individual component were analyzed. The desired characteristics of the system as a whole are given. The flight control system developed, the testing procedures and data reduction methods used, and theoretical frequency response analysis are described.

Development of a high temperature capacitive pressure transducer

NASA Technical Reports Server (NTRS)

Egger, R. L.

1977-01-01

High temperature pressure transducers capable of continuous operation while exposed to 650 C were developed and evaluated over a full-scale differential pressure range of + or - 69 kPa. The design of the pressure transducers was based on the use of a diaphragm to respond to pressure, variable capacitive elements arranged to operate as a differential capacitor to measure diaphragm response and on the use of fused silica for the diaphragm and its supporting assembly. The uncertainty associated with measuring + or - 69 kPa pressures between 20C and 650C was less than + or - 6%.

Mice from lines selectively bred for high voluntary wheel running exhibit lower blood pressure during withdrawal from wheel access.

PubMed

Kolb, Erik M; Kelly, Scott A; Garland, Theodore

2013-03-15

Exercise is known to be rewarding and have positive effects on mental and physical health. Excessive exercise, however, can be the result of an underlying behavioral/physiological addiction. Both humans who exercise regularly and rodent models of exercise addiction sometimes display behavioral withdrawal symptoms, including depression and anxiety, when exercise is denied. However, few studies have examined the physiological state that occurs during this withdrawal period. Alterations in blood pressure (BP) are common physiological indicators of withdrawal in a variety of addictions. In this study, we examined exercise withdrawal in four replicate lines of mice selectively bred for high voluntary wheel running (HR lines). Mice from the HR lines run almost 3-fold greater distances on wheels than those from non-selected control lines, and have altered brain activity as well as increased behavioral despair when wheel access is removed. We tested the hypothesis that male HR mice have an altered cardiovascular response (heart rate, systolic, diastolic, and mean arterial pressure [MAP]) during exercise withdrawal. Measurements using an occlusion tail-cuff system were taken during 8 days of baseline, 6 days of wheel access, and 2 days of withdrawal (wheel access blocked). During withdrawal, HR mice had significantly lower systolic BP, diastolic BP, and MAP than controls, potentially indicating a differential dependence on voluntary wheel running in HR mice. This is the first characterization of a cardiovascular withdrawal response in an animal model of high voluntary exercise. Copyright © 2013. Published by Elsevier Inc.

0.Measurements of H216O Linestrengths and Air-Induced Broadenings and Shifts in the 815-nm Spectral Region

NASA Technical Reports Server (NTRS)

Ponsardin, Patrick L.; Browell, Edward V.

1997-01-01

The linestrengths for 40 absorption lines of H2 16-O water vapor that were located between 813 and 820 nm were measured; most of these lines were selected for their potential usefulness in laser remote measurements of atmospheric humidity using the differential absorption lidar technique. The air-induced pressure-broadening coefficients were also measured for 32 of these lines and the air-induced pressure shift coefficients were measured for 29 lines. These spectroscopic parameters were derived from spectra obtained with an AlGaAs diode laser and two long-path absorption cells. Collisional narrowing effects were observed and were accurately described by a Galatry profile. Comparisons were made with previous experimental work or theoretical calculations as available.

[Conservative therapy of cartilage defects of the upper ankle joint].

PubMed

Smolenski, U C; Best, N; Bocker, B

2008-03-01

Cartilage defects of the upper ankle joint reflect the problem that great force is transmitted and balanced out over a relatively small surface area. As a pathophysiological factor, cartilage-bone contusions play a significant role in the development of cartilage defects of the upper ankle joint. Physiotherapeutic procedures belong to the standard procedures of conservative therapy. The use and selection of the type of therapy is based on empirical considerations and experience and investigations on effectiveness of particular therapies are relatively rare. At present a symptom-oriented therapy of cartilage defects of the upper ankle joint seems to be the most sensible approach. It can be assumed that it makes sense that the symptomatic treatment of cartilage defects or initial stages of arthritis also includes the subsequent symptoms of pain, irritated condition and limited function. This leads to starting points for physiotherapy with respect to pain therapy, optimisation of pressure relationships, avoidance of pressure points, improvement of diffusion and pressure release. In addition to the differential physiotherapeutic findings, the determination of a curative, preventive or rehabilitative procedure is especially important. In physical therapy special importance is placed on a scheduled serial application corresponding to the findings, employing the necessary methods, such as physiotherapy, sport therapy, medical mechanics, manual therapy, massage, electrotherapy and warmth therapy. From this the findings-related therapy is proposed as a practical therapy concept: locomotive apparatus pain therapy, optimisation of pressure relationships, improvement of diffusion and decongestion therapy. Therapy options have been selected base on the current literature and are summarised in tabular form. The art of symptomatic therapy of cartilage defects of the upper ankle joint does not lie in the multitude of sometimes speculative procedures, but in the targeted selection of a therapy regime based on the therapeutic goal, a corresponding application dose and serial design.

Sequence Diversity of Pan troglodytes Subspecies and the Impact of WFDC6 Selective Constraints in Reproductive Immunity

PubMed Central

Ferreira, Zélia; Hurle, Belen; Andrés, Aida M.; Kretzschmar, Warren W.; Mullikin, James C.; Cherukuri, Praveen F.; Cruz, Pedro; Gonder, Mary Katherine; Stone, Anne C.; Tishkoff, Sarah; Swanson, Willie J.; Green, Eric D.; Clark, Andrew G.; Seixas, Susana

2013-01-01

Recent efforts have attempted to describe the population structure of common chimpanzee, focusing on four subspecies: Pan troglodytes verus, P. t. ellioti, P. t. troglodytes, and P. t. schweinfurthii. However, few studies have pursued the effects of natural selection in shaping their response to pathogens and reproduction. Whey acidic protein (WAP) four-disulfide core domain (WFDC) genes and neighboring semenogelin (SEMG) genes encode proteins with combined roles in immunity and fertility. They display a strikingly high rate of amino acid replacement (dN/dS), indicative of adaptive pressures during primate evolution. In human populations, three signals of selection at the WFDC locus were described, possibly influencing the proteolytic profile and antimicrobial activities of the male reproductive tract. To evaluate the patterns of genomic variation and selection at the WFDC locus in chimpanzees, we sequenced 17 WFDC genes and 47 autosomal pseudogenes in 68 chimpanzees (15 P. t. troglodytes, 22 P. t. verus, and 31 P. t. ellioti). We found a clear differentiation of P. t. verus and estimated the divergence of P. t. troglodytes and P. t. ellioti subspecies in 0.173 Myr; further, at the WFDC locus we identified a signature of strong selective constraints common to the three subspecies in WFDC6—a recent paralog of the epididymal protease inhibitor EPPIN. Overall, chimpanzees and humans do not display similar footprints of selection across the WFDC locus, possibly due to different selective pressures between the two species related to immune response and reproductive biology. PMID:24356879

Evolution of the core and pan-genome of Streptococcus: positive selection, recombination, and genome composition

PubMed Central

Lefébure, Tristan; Stanhope, Michael J

2007-01-01

Background The genus Streptococcus is one of the most diverse and important human and agricultural pathogens. This study employs comparative evolutionary analyses of 26 Streptococcus genomes to yield an improved understanding of the relative roles of recombination and positive selection in pathogen adaptation to their hosts. Results Streptococcus genomes exhibit extreme levels of evolutionary plasticity, with high levels of gene gain and loss during species and strain evolution. S. agalactiae has a large pan-genome, with little recombination in its core-genome, while S. pyogenes has a smaller pan-genome and much more recombination of its core-genome, perhaps reflecting the greater habitat, and gene pool, diversity for S. agalactiae compared to S. pyogenes. Core-genome recombination was evident in all lineages (18% to 37% of the core-genome judged to be recombinant), while positive selection was mainly observed during species differentiation (from 11% to 34% of the core-genome). Positive selection pressure was unevenly distributed across lineages and biochemical main role categories. S. suis was the lineage with the greatest level of positive selection pressure, the largest number of unique loci selected, and the largest amount of gene gain and loss. Conclusion Recombination is an important evolutionary force in shaping Streptococcus genomes, not only in the acquisition of significant portions of the genome as lineage specific loci, but also in facilitating rapid evolution of the core-genome. Positive selection, although undoubtedly a slower process, has nonetheless played an important role in adaptation of the core-genome of different Streptococcus species to different hosts. PMID:17475002

Differential paralog divergence modulates genome evolution across yeast species

PubMed Central

Lynch, Bryony; Huang, Mei; Alcantara, Erica; DeSevo, Christopher G.; Pai, Dave A.; Hoang, Margaret L.

2017-01-01

Evolutionary outcomes depend not only on the selective forces acting upon a species, but also on the genetic background. However, large timescales and uncertain historical selection pressures can make it difficult to discern such important background differences between species. Experimental evolution is one tool to compare evolutionary potential of known genotypes in a controlled environment. Here we utilized a highly reproducible evolutionary adaptation in Saccharomyces cerevisiae to investigate whether experimental evolution of other yeast species would select for similar adaptive mutations. We evolved populations of S. cerevisiae, S. paradoxus, S. mikatae, S. uvarum, and interspecific hybrids between S. uvarum and S. cerevisiae for ~200–500 generations in sulfate-limited continuous culture. Wild-type S. cerevisiae cultures invariably amplify the high affinity sulfate transporter gene, SUL1. However, while amplification of the SUL1 locus was detected in S. paradoxus and S. mikatae populations, S. uvarum cultures instead selected for amplification of the paralog, SUL2. We measured the relative fitness of strains bearing deletions and amplifications of both SUL genes from different species, confirming that, converse to S. cerevisiae, S. uvarum SUL2 contributes more to fitness in sulfate limitation than S. uvarum SUL1. By measuring the fitness and gene expression of chimeric promoter-ORF constructs, we were able to delineate the cause of this differential fitness effect primarily to the promoter of S. uvarum SUL1. Our data show evidence of differential sub-functionalization among the sulfate transporters across Saccharomyces species through recent changes in noncoding sequence. Furthermore, these results show a clear example of how such background differences due to paralog divergence can drive changes in genome evolution. PMID:28196070

Population-genetic models of sex-limited genomic imprinting.

PubMed

Kelly, S Thomas; Spencer, Hamish G

2017-06-01

Genomic imprinting is a form of epigenetic modification involving parent-of-origin-dependent gene expression, usually the inactivation of one gene copy in some tissues, at least, for some part of the diploid life cycle. Occurring at a number of loci in mammals and flowering plants, this mode of non-Mendelian expression can be viewed more generally as parentally-specific differential gene expression. The effects of natural selection on genetic variation at imprinted loci have previously been examined in a several population-genetic models. Here we expand the existing one-locus, two-allele population-genetic models of viability selection with genomic imprinting to include sex-limited imprinting, i.e., imprinted expression occurring only in one sex, and differential viability between the sexes. We first consider models of complete inactivation of either parental allele and these models are subsequently generalized to incorporate differential expression. Stable polymorphic equilibrium was possible without heterozygote advantage as observed in some prior models of imprinting in both sexes. In contrast to these latter models, in the sex-limited case it was critical whether the paternally inherited or maternally inherited allele was inactivated. The parental origin of inactivated alleles had a different impact on how the population responded to the different selection pressures between the sexes. Under the same fitness parameters, imprinting in the other sex altered the number of possible equilibrium states and their stability. When the parental origin of imprinted alleles and the sex in which they are inactive differ, an allele cannot be inactivated in consecutive generations. The system dynamics became more complex with more equilibrium points emerging. Our results show that selection can interact with epigenetic factors to maintain genetic variation in previously unanticipated ways. Copyright © 2017 Elsevier Inc. All rights reserved.

System Would Regulate Low Gas Pressure

NASA Technical Reports Server (NTRS)

Frazer, Robert E.

1994-01-01

System intended to maintain gases in containers at pressures near atmospheric. Includes ballast volume in form of underinflated balloon that communicates with working volume. Balloon housed in rigid chamber not subjected to extremes of temperature of working volume. Pressure in chamber surrounding balloon regulated at ambient atmospheric pressure or at constant small differential pressure above or below ambient. Expansion and contraction of balloon accommodates expansion or contraction of gas during operational heating or cooling in working volume, maintaining pressure in working volume at ambient or constant differential above or below ambient. Gas lost from system due to leakage or diffusion, low-pressure sensor responds, signaling valve actuators to supply more gas to working volume. If pressure rises too high, overpressure relief valve opens before excessive pressure damages system.

A transmission-line model of back-cavity dynamics for in-plane pressure-differential microphones.

PubMed

Kim, Donghwan; Kuntzman, Michael L; Hall, Neal A

2014-11-01

Pressure-differential microphones inspired by the hearing mechanism of a special parasitoid fly have been described previously. The designs employ a beam structure that rotates about two pivots over an enclosed back volume. The back volume is only partially enclosed due to open slits around the perimeter of the beam. The open slits enable incoming sound waves to affect the pressure profile in the microphone's back volume. The goal of this work is to study the net moment applied to pressure-differential microphones by an incoming sound wave, which in-turn requires modeling the acoustic pressure distribution within the back volume. A lumped-element distributed transmission-line model of the back volume is introduced for this purpose. It is discovered that the net applied moment follows a low-pass filter behavior such that, at frequencies below a corner frequency depending on geometrical parameters of the design, the applied moment is unaffected by the open slits. This is in contrast to the high-pass filter behavior introduced by barometric pressure vents in conventional omnidirectional microphones. The model accurately predicts observed curvature in the frequency response of a prototype pressure-differential microphone 2 mm × 1 mm × 0.5 mm in size and employing piezoelectric readout.

Selective microenvironmental effects play a role in shaping genetic diversity and structure in a Phaseolus vulgaris L. landrace: implications for on-farm conservation.

PubMed

Tiranti, B; Negri, V

2007-12-01

Little is known about the organization of landrace diversity and about the forces that shape and maintain within- and among-landrace population diversity. However, this knowledge is essential for conservation and breeding activities. The first aim of this study was to obtain some insight into how variation has been sculptured within a cultivated environment and to identify the loci that potentially underlie selective effects by using a Phaseolus vulgaris L. landrace case study whose natural and human environment and morpho-physiological traits are known in detail. The second aim of this study was to define an appropriate on-farm conservation strategy which can serve as a model for other populations. The farmers' populations of this threatened landrace were examined with 28 single sequence repeat molecular markers. The landrace appears to be a genetically structured population in which substantial diversity is maintained at the subpopulation level (62% of the total variance). Evidence of locus-specific selective effects was obtained for five of the 13 loci-differentiating subpopulations. Their role is discussed. Our data suggest that a complex interaction of factors (differential microenvironmental selection pressures by farmers and by biotic and abiotic conditions, migration rate and drift) explains the observed pattern of diversity. Appropriate on-farm conservation of a structured landrace requires the maintenance of the entire population.

Emerging prion disease drives host selection in a wildlife population

USGS Publications Warehouse

Robinson, Stacie J.; Samuel, Michael D.; Johnson, Chad J.; Adams, Marie; McKenzie, Debbie I.

2012-01-01

Infectious diseases are increasingly recognized as an important force driving population dynamics, conservation biology, and natural selection in wildlife populations. Infectious agents have been implicated in the decline of small or endangered populations and may act to constrain population size, distribution, growth rates, or migration patterns. Further, diseases may provide selective pressures that shape the genetic diversity of populations or species. Thus, understanding disease dynamics and selective pressures from pathogens is crucial to understanding population processes, managing wildlife diseases, and conserving biological diversity. There is ample evidence that variation in the prion protein gene (PRNP) impacts host susceptibility to prion diseases. Still, little is known about how genetic differences might influence natural selection within wildlife populations. Here we link genetic variation with differential susceptibility of white-tailed deer to chronic wasting disease (CWD), with implications for fitness and disease-driven genetic selection. We developed a single nucleotide polymorphism (SNP) assay to efficiently genotype deer at the locus of interest (in the 96th codon of the PRNP gene). Then, using a Bayesian modeling approach, we found that the more susceptible genotype had over four times greater risk of CWD infection; and, once infected, deer with the resistant genotype survived 49% longer (8.25 more months). We used these epidemiological parameters in a multi-stage population matrix model to evaluate relative fitness based on genotype-specific population growth rates. The differences in disease infection and mortality rates allowed genetically resistant deer to achieve higher population growth and obtain a long-term fitness advantage, which translated into a selection coefficient of over 1% favoring the CWD-resistant genotype. This selective pressure suggests that the resistant allele could become dominant in the population within an evolutionarily short time frame. Our work provides a rare example of a quantifiable disease-driven selection process in a wildlife population, demonstrating the potential for infectious diseases to alter host populations. This will have direct bearing on the epidemiology, dynamics, and future trends in CWD transmission and spread. Understanding genotype-specific epidemiology will improve predictive models and inform management strategies for CWD-affected cervid populations.

Chemical pump study for Pioneer Venus program

NASA Technical Reports Server (NTRS)

Rotheram, M.

1973-01-01

Two chemical pumps were designed for the Pioneer Venus large probe mass spectrometer. Factors involved in the design selection are reviewed. One pump is designed to process a sample of the Venus atmosphere to remove the major component, carbon dioxide, so that the minor, inert components may be measured with greater sensitivity. The other pump is designed to promote flow of atmospheric gas through a pressure reduction inlet system. This pump, located downstream from the mass spectrometer sampling point, provides the pressure differential required for flow through the inlet system. Both pumps utilize the reaction of carbon dioxide with lithium hydroxide. The available data for this reaction was reviewed with respect to the proposed applications, and certain deficiencies in reaction rate data at higher carbon dioxide pressures noted. The chemical pump designed for the inert gas experiment has an estimated volume of 30 cu cm and weight of 80 grams, exclusive of the four valves required for the operation. The chemical pump for the pressure reduction inlet system is designed for a total sample of 0.3 bar liter during the Venus descent.

Early differentiation of the Moon: Experimental and modeling studies

NASA Technical Reports Server (NTRS)

Longhi, J.

1986-01-01

Major accomplishments include the mapping out of liquidus boundaries of lunar and meteoritic basalts at low pressure; the refinement of computer models that simulate low pressure fractional crystallization; the development of a computer model to calculate high pressure partial melting of the lunar and Martian interiors; and the proposal of a hypothesis of early lunar differentiation based upon terrestrial analogs.

One-stage free-vortex aerodynamic window with pressure ratio 100 and atmospheric exhaust

NASA Astrophysics Data System (ADS)

Malkov, Victor M.; Trilis, A. V.; Savin, Andrew V.; Druzhinin, S. L.

2005-03-01

The aerodynamic windows (AW) are intended for a high power extraction from the gas laser optical cavity, where the pressure is much lower than environment pressure. The main requirements for the aerodynamic windows are to satisfy a low level of optical disturbances in a laser beam extraction channel and an air leakage absence into the optical cavity. Free vortex AW are most economic from a point of working gas consumption and the greatest pressure differential is realized on them at an exhaust to atmosphere. For ideal gas it is possible to receive as much as large pressure differential, however for real gas a pressure differential more than P>=50 is difficult to achieve. To achieve the pressure ratio 100 in free vortex single-stage AW the method of stabilizing of boundary layer was used. The gas of curtain was decelerated in the diffuser and was exhausted into the atmosphere straightly. The pressure recovery improvement was achieved by using the boundary layer blowing inside the diffuser. Only 10% of total mass flow was used for boundary layer blowing.

High polymorphism in MHC-DRB genes in golden snub-nosed monkeys reveals balancing selection in small, isolated populations.

PubMed

Zhang, Pei; Huang, Kang; Zhang, Bingyi; Dunn, Derek W; Chen, Dan; Li, Fan; Qi, Xiaoguang; Guo, Songtao; Li, Baoguo

2018-03-13

Maintaining variation in immune genes, such as those of the major histocompatibility complex (MHC), is important for individuals in small, isolated populations to resist pathogens and parasites. The golden snub-nosed monkey (Rhinopithecus roxellana), an endangered primate endemic to China, has experienced a rapid reduction in numbers and severe population fragmentation over recent years. For this study, we measured the DRB diversity among 122 monkeys from three populations in the Qinling Mountains, and estimated the relative importance of different agents of selection in maintaining variation of DRB genes. We identified a total of 19 DRB sequences, in which five alleles were novel. We found high DRB variation in R. roxellana and three branches of evidence suggesting that balancing selection has contributed to maintaining MHC polymorphism over the long term in this species: i) different patterns of both genetic diversity and population differentiation were detected at MHC and neutral markers; ii) an excess of non-synonymous substitutions compared to synonymous substitutions at antigen binding sites, and maximum-likelihood-based random-site models, showed significant positive selection; and iii) phylogenetic analyses revealed a pattern of trans-species evolution for DRB genes. High levels of DRB diversity in these R. roxellana populations may reflect strong selection pressure in this species. Patterns of genetic diversity and population differentiation, positive selection, as well as trans-species evolution, suggest that pathogen-mediated balancing selection has contributed to maintaining MHC polymorphism in R. roxellana over the long term. This study furthers our understanding of the role pathogen-mediated balancing selection has in maintaining variation in MHC genes in small and fragmented populations of free-ranging vertebrates.

Calibration-free sensor for pressure and H2O concentration in headspace of sterile vial using tunable diode laser absorption spectroscopy.

PubMed

Cai, Tingdong; Gao, Guangzhen; Liu, Ying

2013-11-10

Tunable diode laser absorption measurements of pressure and H2O concentration in the headspace of vials using a distributed-feedback (DFB) diode laser near 1.4 μm are reported. A H2O line located near 7161.41 cm(-1) is selected based on its strong absorption strength and isolation from interference of neighboring transitions. Direct absorption spectra of H2O are obtained for the measurement path as well as the reference path by scanning the laser wavelength. The pressure and H2O vapor concentration in the headspace of a vial are inferred from a differential absorption signal, which is the difference between the measured and the referenced absorbance spectra. This sensor is calibration-free and no purge gas is needed. The demonstrated capability would enable measurements of pressure and H2O concentration in the headspace of vials within 2.21% and 2.86%, respectively. A precision of 1.02 Torr and 390 ppm is found for the pressure and H2O concentration, respectively. A set of measurements for commercial freeze-dried products are also performed to illustrate the usefulness of this sensor.

Rates of morphological evolution, asymmetry and morphological integration of shell shape in scallops.

PubMed

Sherratt, Emma; Serb, Jeanne M; Adams, Dean C

2017-12-08

Rates of morphological evolution vary across different taxonomic groups, and this has been proposed as one of the main drivers for the great diversity of organisms on Earth. Of the extrinsic factors pertaining to this variation, ecological hypotheses feature prominently in observed differences in phenotypic evolutionary rates across lineages. But complex organisms are inherently modular, comprising distinct body parts that can be differentially affected by external selective pressures. Thus, the evolution of trait covariation and integration in modular systems may also play a prominent role in shaping patterns of phenotypic diversity. Here we investigate the role ecological diversity plays in morphological integration, and the tempo of shell shape evolution and of directional asymmetry in bivalved scallops. Overall, the shape of both valves and the magnitude of asymmetry of the whole shell (difference in shape between valves) are traits that are evolving fast in ecomorphs under strong selective pressures (gliders, recessers and nestling), compared to low rates observed in other ecomorphs (byssal-attaching, free-living and cementing). Given that different parts of an organism can be under different selective pressures from the environment, we also examined the degree of evolutionary integration between the valves as it relates to ecological shifts. We find that evolutionary morphological integration is consistent and surprisingly high across species, indicating that while the left and right valves of a scallop shell are diversifying in accordance with ecomorphology, they are doing so in a concerted fashion. Our study on scallops adds another strong piece of evidence that ecological shifts play an important role in the tempo and mode of morphological evolution. Strong selective pressures from the environment, inferred from the repeated evolution of distinct ecomorphs, have influenced the rate of morphological evolution in valve shape and the magnitude of asymmetry between valves. Our observation that morphological integration of the valves making up the shell is consistently strong suggests tight developmental pathways are responsible for the concerted evolution of these structures while environmental pressures are driving whole shell shape. Finally, our study shows that directional asymmetry in shell shape among species is an important aspect of scallop macroevolution.

The importance of valve alignment in determining the pressure/flow characteristics of differential pressure shunt valves with anti-gravity devices.

PubMed

Francel, P C; Stevens, F A; Tompkins, P; Pollay, M

2001-02-01

The proper functioning of shunt valves in vivo is dependent on many factors, including the valve itself, the anti-siphon device or ASD (if included), patency of inlet and outlet tubing, and location of the valve. One important, but sometimes overlooked, consideration in valve function is the valve location relative to the tip of the ventricular inlet catheter. As with any pressure measurement, the zero or reference position is an important concept. In the case of shunt valves, the position of the proximal inlet catheter tip is fixed and therefore serves as the reference point for all pressure measurements. This study was conducted to document the importance of this relationship for the pressure/flow characteristics of the shunt valve. We bench-tested differential pressure valves (with integral anti-gravity devices; AGDs) from three manufacturers. Valves were connected to an "infinite" reservoir, and the starting head pressure for each was determined from product inserts. The inlet catheter tip was fixed at this position, and the valve body was moved in relation to the inlet catheter tip. Outflow rates were determined gravimetrically for positions varying between 4 cm above and 8 cm below the inlet catheter tip. All differential pressure valves utilized in this study that contained AGDs showed significant increases in outflow rate as the valve body was moved incrementally below the level of the inlet catheter tip. To allow functioning as a zero-hydrostatic pressure differential pressure valve, the AGD and the inlet catheter tip should be aligned at the same horizontal level.

Selective Inhibition of the Oxidation of Ferrous Iron or Sulfur in Thiobacillus ferrooxidans

PubMed Central

Harahuc, Lesia; Lizama, Hector M.; Suzuki, Isamu

2000-01-01

The oxidation of either ferrous iron or sulfur by Thiobacillus ferrooxidans was selectively inhibited or controlled by various anions, inhibitors, and osmotic pressure. Iron oxidation was more sensitive than sulfur oxidation to inhibition by chloride, phosphate, and nitrate at low concentrations (below 0.1 M) and also to inhibition by azide and cyanide. Sulfur oxidation was more sensitive than iron oxidation to the inhibitory effect of high osmotic pressure. These differences were evident not only between iron oxidation by iron-grown cells and sulfur oxidation by sulfur-grown cells but also between the iron and sulfur oxidation activities of the same iron-grown cells. Growth experiments with ferrous iron or sulfur as an oxidizable substrate confirmed the higher sensitivity of iron oxidation to inhibition by phosphate, chloride, azide, and cyanide. Sulfur oxidation was actually stimulated by 50 mM phosphate or chloride. Leaching of Fe and Zn from pyrite (FeS2) and sphalerite (ZnS) by T. ferrooxidans was differentially affected by phosphate and chloride, which inhibited the solubilization of Fe without significantly affecting the solubilization of Zn. PMID:10698768

Indications for endoscopic third ventriculostomy in normal pressure hydrocephalus.

PubMed

Paidakakos, Nikolaos; Borgarello, S; Naddeo, M

2012-01-01

Controversies remain regarding the proper diagnostic studies and prediction of outcome in patients with normal pressure hydrocephalus (NPH), and their management remains controversial. We propose a preoperative assessment routine the aim of which is to correctly select NPH patients, and to differentiate between them in terms of surgical treatment, identifying probable endoscopic third ventriculostomy (ETV) responders. We prospectively considered a group of 44 patients with suspected NPH on the basis of clinical symptoms and neuroradiological evidence, who have undergone supplemental diagnostic testing (tap test, external lumbar drainage, cerebrospinal fluid outflow resistance [Rout] determination through lumbar and ventricular infusion test). All 44 of these patients were treated with either shunt procedures or ETV. To choose the kind of treatment (shunt or ETV), we evaluated the individual response during infusion tests. The efficacy of both surgical techniques was approximately 70%, with a significantly lower complication rate for ETV. We evaluated the correlation between the various tests and the postoperative outcomes both for shunting and for ETV. Rout proved useful for preoperative assessment and choice of treatment. In carefully selected patients, ETV had qualitative results similar to shunting, presenting significantly fewer complications.

Miniaturized pressurization system

DOEpatents

Whitehead, John C.; Swink, Don G.

1991-01-01

The invention uses a fluid stored at a low pressure and provides the fluid at a high pressure. The invention allows the low pressure fluid to flow to a fluid bore of a differential pump and from the pump to a fluid pressure regulator. After flowing through the regulator the fluid is converted to a gas which is directed to a gas bore of the differential pump. By controlling the flow of gas entering and being exhausted from the gas bore, the invention provides pressure to the fluid. By setting the regulator, the high pressure fluid can be set at predetermined values. Because the invention only needs a low pressure fluid, the inventive apparatus has a low mass, and therefore would be useful in rocket propulsion systems.

On dangerous ground: the evolution of body armour in cordyline lizards.

PubMed

Broeckhoven, Chris; El Adak, Yousri; Hui, Cang; Van Damme, Raoul; Stankowich, Theodore

2018-06-13

Animal body armour is often considered an adaptation that protects prey against predatory attacks, yet comparative studies that link the diversification of these allegedly protective coverings to differential predation risk or pressure are scarce. Here, we examine the evolution of body armour, including spines and osteoderms, in Cordylinae, a radiation of southern African lizards. Using phylogenetic comparative methods, we attempt to identify the ecological and environmental correlates of body armour that may hint at the selective pressures responsible for defensive trait diversification. Our results show that species inhabiting arid environments are more likely to possess elaborated body armour, specifically osteoderms. We did not find any effect of estimated predation pressure or risk on the degree of body armour. These findings suggest that body armour might not necessarily evolve in response to direct interactions with predators, but rather as a result of increased habitat-mediated predation risk. Furthermore, we discuss the possibility that osteoderms might have been shaped by factors unrelated to predation. © 2018 The Author(s).

Seed predators exert selection on the subindividual variation of seed size.

PubMed

Sobral, M; Guitián, J; Guitián, P; Larrinaga, A R

2014-07-01

Subindividual variation among repeated organs in plants constitutes an overlooked level of variation in phenotypic selection studies, despite being a major component of phenotypic variation. Animals that interact with plants could be selective agents on subindividual variation. This study examines selective pressures exerted during post-dispersal seed predation and germination on the subindividual variation of seed size in hawthorn (Crataegus monogyna). With a seed offering experiment and a germination test, we estimated phenotypic selection differentials for average and subindividual variation of seed size due to seed predation and germination. Seed size affects germination, growth rate and the probability of an individual seed of escaping predation. Longer seeds showed higher germination rates, but this did not result in significant selection on phenotypes of the maternal trees. On the other hand, seed predators avoided wider seeds, and by doing so exerted phenotypic selection on adult average and subindividual variation of seed size. The detected selection on subindividual variation suggests that the levels of phenotypic variation within individual plants may be, at least partly, the adaptive consequence of animal-mediated selection. © 2013 German Botanical Society and The Royal Botanical Society of the Netherlands.

Piston rod seal for a Stirling engine

DOEpatents

Shapiro, Wilbur

1984-01-01

In a piston rod seal for a Stirling engine, a hydrostatic bearing and differential pressure regulating valve are utilized to provide for a low pressure differential across a rubbing seal between the hydrogen and oil so as to reduce wear on the seal.

Low Differential Pressure Generator

NASA Technical Reports Server (NTRS)

Stout, Stephen J. (Inventor); Deyoe, Richard T. (Inventor)

1997-01-01

A method and apparatus for evaluating low differential pressure transducers includes a pressure generator in the form of a piston-cylinder assembly having a piston that may be manually positioned precisely within the cylinder to change the volume and thus the pressure at respective sides of the piston. At one side of the piston the cylinder communicates with a first chamber and at the other side of the piston the cylinder communicates with a second chamber, the first and second chambers being formed within a common tank by a partition wall. The chambers each communicate with the transducer to be evaluated and a standard pre-calibrated transducer the transducers being connected fluidly in parallel so that a pressure differential between air in the two chambers resulting from movement of the piston within the cylinder is communicated to both the transducer to be evaluated and the standard transducer, and the outputs of the transducers is observed and recorded.

AFLP genome scan in the black rat (Rattus rattus) from Madagascar: detecting genetic markers undergoing plague-mediated selection.

PubMed

Tollenaere, C; Duplantier, J-M; Rahalison, L; Ranjalahy, M; Brouat, C

2011-03-01

The black rat (Rattus rattus) is the main reservoir of plague (Yersinia pestis infection) in Madagascar's rural zones. Black rats are highly resistant to plague within the plague focus (central highland), whereas they are susceptible where the disease is absent (low altitude zone). To better understand plague wildlife circulation and host evolution in response to a highly virulent pathogen, we attempted to determine genetic markers associated with plague resistance in this species. To this purpose, we combined a population genomics approach and an association study, both performed on 249 AFLP markers, in Malagasy R. rattus. Simulated distributions of genetic differentiation were compared to observed data in four independent pairs, each consisting of one population from the plague focus and one from the plague-free zone. We found 22 loci (9% of 249) with higher differentiation in at least two independent population pairs or with combining P-values over the four pairs significant. Among the 22 outlier loci, 16 presented significant association with plague zone (plague focus vs. plague-free zone). Population genetic structure inferred from outlier loci was structured by plague zone, whereas the neutral loci dataset revealed structure by geography (eastern vs. western populations). A phenotype association study revealed that two of the 22 loci were significantly associated with differentiation between dying and surviving rats following experimental plague challenge. The 22 outlier loci identified in this study may undergo plague selective pressure either directly or more probably indirectly due to hitchhiking with selected loci. © 2010 Blackwell Publishing Ltd.

The Distinct Effects of Estrogen and Hydrostatic Pressure on Mesenchymal Stem Cells Differentiation: Involvement of Estrogen Receptor Signaling.

PubMed

Zhao, Ying; Yi, Fei-Zhou; Zhao, Yin-Hua; Chen, Yong-Jin; Ma, Heng; Zhang, Min

2016-10-01

This study aimed to investigate the differential and synergistic effects of mechanical stimulation and estrogen on the proliferation and osteogenic or chondrogenic differentiation potential of bone marrow mesenchymal stem cells (BMSCs) and the roles of estrogen receptor (ER) in them. BMSCs were isolated and cultured using the whole bone marrow adherence method, and flow cytometry was used to identify the surface marker molecules of BMSCs. Cells were pre-treated with 1 nM 17β-estradiol or 1 nM of the estrogen receptor antagonist tamoxifen. Then, the cells were stimulated with hydrostatic pressure. Assessment included flow cytometry analysis of the cell cycle; immunofluorescent staining for F-actin; protein quantification for MAPK protein; and mRNA analysis for Col I, OCN, OPN and BSP after osteogenic induction and Sox-9, Aggrecan and Col-II after chondrogenic induction. Hydrostatic pressure (90 kPa/1 h) and 1 nM 17β-estradiol enhanced the cellular proliferation ability and the cytoskeleton activity but without synergistic biological effects. Estrogen activated ERKs and JNKs simultaneously and promoted the osteogenic differentiation, whereas the pressure just caused JNK-1/2 activation and promoted the chondrogenic differentiation of BMSCs. Estrogen had antagonism effect on chondrogenic promotion of hydrostatic pressure. Mechanobiological effects of hydrostatic pressure are closely associated with ERα activity. MAPK molecules and F-actin were likely to be important mediator molecules in the ER-mediated mechanotransduction of BMSCs.

Reversible effects of oxygen partial pressure on genes associated with placental angiogenesis and differentiation in primary-term cytotrophoblast cell culture.

PubMed

Debiève, F; Depoix, C; Gruson, D; Hubinont, C

2013-09-01

Timely regulated changes in oxygen partial pressure are important for placental formation. Disturbances could be responsible for pregnancy-related diseases like preeclampsia and intrauterine growth restriction. We aimed to (i) determine the effect of oxygen partial pressure on cytotrophoblast differentiation; (ii) measure mRNA expression and protein secretion from genes associated with placental angiogenesis; and (iii) determine the reversibility of these effects at different oxygen partial pressures. Term cytotrophoblasts were incubated at 21% and 2.5% O2 for 96 hr, or were switched between the two oxygen concentrations after 48 hr. Real-time PCR and enzyme-linked immunosorbent assays (ELISAs) were used to evaluate cell fusion and differentiation, measuring transcript levels for those genes involved in cell fusion and placental angiogenesis, including VEGF, PlGF, VEGFR1, sVEGFR1, sENG, INHA, and GCM1. Cytotrophoblasts underwent fusion and differentiation in 2.5% O2 . PlGF expression was inhibited while sVEGFR1 expression increased. VEGF and sENG mRNA expressions increased in 2.5% compared to 21% O2 , but no protein was detected in the cell supernatants. Finally, GCM1 mRNA expression increased during trophoblast differentiation at 21% O2 , but was inhibited at 2.5% O2 . These mRNA expression effects were reversed by returning the cells to 21% O2 . Thus, low-oxygen partial pressure does not inhibit term-cytotrophoblast cell fusion and differentiation in vitro. Lowering the oxygen partial pressure from 21% to 2.5% caused normal-term trophoblasts to reversibly modify their expression of genes associated with placental angiogenesis. This suggests that modifications observed in pregnancy diseases such as preeclampsia or growth retardation are probably due to an extrinsic effect on trophoblasts. Copyright © 2013 Wiley Periodicals, Inc.

Fundamental differences in diversity and genomic population structure between Atlantic and Pacific Prochlorococcus.

PubMed

Kashtan, Nadav; Roggensack, Sara E; Berta-Thompson, Jessie W; Grinberg, Maor; Stepanauskas, Ramunas; Chisholm, Sallie W

2017-09-01

The Atlantic and Pacific Oceans represent different biogeochemical regimes in which the abundant marine cyanobacterium Prochlorococcus thrives. We have shown that Prochlorococcus populations in the Atlantic are composed of hundreds of genomically, and likely ecologically, distinct coexisting subpopulations with distinct genomic backbones. Here we ask if differences in the ecology and selection pressures between the Atlantic and Pacific are reflected in the diversity and genomic composition of their indigenous Prochlorococcus populations. We applied large-scale single-cell genomics and compared the cell-by-cell genomic composition of wild populations of co-occurring cells from samples from Station ALOHA off Hawaii, and from Bermuda Atlantic Time Series Station off Bermuda. We reveal fundamental differences in diversity and genomic structure of populations between the sites. The Pacific populations are more diverse than those in the Atlantic, composed of significantly more coexisting subpopulations and lacking dominant subpopulations. Prochlorococcus from the two sites seem to be composed of mostly non-overlapping distinct sets of subpopulations with different genomic backbones-likely reflecting different sets of ocean-specific micro-niches. Furthermore, phylogenetically closely related strains carry ocean-associated nutrient acquisition genes likely reflecting differences in major selection pressures between the oceans. This differential selection, along with geographic separation, clearly has a significant role in shaping these populations.

RADON PRESSURE DIFFERENTIAL PROJECT - PHASE I - FLORIDA RESEARCH PROGRAM

EPA Science Inventory

The report gives results of tests on 70 central Florida houses to assess and characterize pressure differentials in new (age 5 years or less) Florida houses. Blower door tests determined house airtightness and air distribution system leakage. The 70 houses had an average airtight...

Oxidation Behavior of Carbon Fiber-Reinforced Composites

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2008-01-01

OXIMAP is a numerical (FEA-based) solution tool capable of calculating the carbon fiber and fiber coating oxidation patterns within any arbitrarily shaped carbon silicon carbide composite structure as a function of time, temperature, and the environmental oxygen partial pressure. The mathematical formulation is derived from the mechanics of the flow of ideal gases through a chemically reacting, porous solid. The result of the formulation is a set of two coupled, non-linear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined at each time step using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The non-linear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual finite element method, allowing for the solution of the differential equations numerically.

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

Stenosis differentially affects subendocardial and subepicardial arterioles in vivo.

PubMed

Merkus, D; Vergroesen, I; Hiramatsu, O; Tachibana, H; Nakamoto, H; Toyota, E; Goto, M; Ogasawara, Y; Spaan, J A; Kajiya, F

2001-04-01

The presence of a coronary stenosis results primarily in subendocardial ischemia. Apart from the decrease in coronary perfusion pressure, a stenosis also decreases coronary flow pulsations. Applying a coronary perfusion system, we compared the autoregulatory response of subendocardial (n = 10) and subepicardial (n = 12) arterioles (<120 microm) after stepwise decreases in coronary arterial pressure from 100 to 70, 50, and 30 mmHg in vivo in dogs (n = 9). Pressure steps were performed with and without stenosis on the perfusion line. Maximal arteriolar diameter during the cardiac cycle was determined and normalized to its value at 100 mmHg. The initial decrease in diameter during reductions in pressure was significantly larger at the subendocardium. Diameters of subendocardial and subepicardial arterioles were similar 10--15 s after the decrease in pressure without stenosis. However, stenosis decreased the dilatory response of the subendocardial arterioles significantly. This decreased dilatory response was also evidenced by a lower coronary inflow at similar average pressure in the presence of a stenosis. Inhibition of nitric oxide production with N(G)-monomethyl-L-arginine abrogated the effect of the stenosis on flow. We conclude that the decrease in pressure caused by a stenosis in vivo results in a larger decrease in diameter of the subendocardial arterioles than in the subepicardial arterioles, and furthermore stenosis selectively decreases the dilatory response of subendocardial arterioles. These two findings expand our understanding of subendocardial vulnerability to ischemia.

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

NASA Astrophysics Data System (ADS)

Rodi, A. R.; Leon, D. C.

2012-05-01

Geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system on the University of Wyoming King Air research aircraft are used to estimate acceleration effects on static pressure measurement. Using data collected during periods of accelerated flight, comparison of measured pressure with that derived from GNSS/IMU geometric altitude show that errors exceeding 150 Pa can occur which is significant in airspeed and atmospheric air motion determination. A method is developed to predict static pressure errors from analysis of differential pressure measurements from a Rosemount model 858 differential pressure air velocity probe. The method was evaluated with a carefully designed probe towed on connecting tubing behind the aircraft - a "trailing cone" - in steady flight, and shown to have a precision of about ±10 Pa over a wide range of conditions including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, compared to the GNSS/IMU data, this algorithm predicts corrections to a precision of better than ±20 Pa. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are examined.

Variation in functional responses to water stress and differentiation between natural allopolyploid populations in the Brachypodium distachyon species complex.

PubMed

Martínez, Luisa M; Fernández-Ocaña, Ana; Rey, Pedro J; Salido, Teresa; Amil-Ruiz, Francisco; Manzaneda, Antonio J

2018-06-08

Some polyploid species show enhanced physiological tolerance to drought compared with their progenitors. However, very few studies have examined the consistency of physiological drought response between genetically differentiated natural polyploid populations, which is key to evaluation of the importance of adaptive evolution after polyploidization in those systems where drought exerts a selective pressure. A comparative functional approach was used to investigate differentiation of drought-tolerance-related traits in the Brachypodium species complex, a model system for grass polyploid adaptive speciation and functional genomics that comprises three closely related annual species: the two diploid parents, B. distachyon and B. stacei, and the allotetraploid derived from them, B. hybridum. Differentiation of drought-tolerance-related traits between ten genetically distinct B. hybridum populations and its ecological correlates was further analysed. The functional drought response is overall well differentiated between Brachypodium species. Brachypodium hybridum allotetraploids showed a transgressive expression pattern in leaf phytohormone content in response to drought. In contrast, other B. hybridum physiological traits correlated to B. stacei ones. Particularly, proline and water content were the traits that best discriminated these species from B. distachyon under drought. After polyploid formation and/or colonization, B. hybridum populations have adaptively diverged physiologically and genetically in response to variations in aridity.

Influence of Partial O₂ Pressure on the Adhesion, Proliferation, and Osteogenic Differentiation of Human Dental Pulp Stem Cells on β-Tricalcium Phosphate Scaffold.

PubMed

Viña-Almunia, Jose; Mas-Bargues, Cristina; Borras, Consuelo; Gambini, Juan; El Alami, Marya; Sanz-Ros, Jorge; Peñarrocha, Miguel; Vina, Jose

To analyze, in vitro, the influence of O₂ pressure on the adhesion, proliferation, and osteogenic differentiation of human dental pulp stem cells (DPSC) on β-tricalcium phosphate (β-TCP) scaffold. DPSC, positive for the molecular markers CD133, Oct4, Nestin, Stro-1, and CD34, and negative for CD45, were isolated from extracted third molars. Experiments were started by seeding 200,000 cells on β-TCP cultured under 3% or 21% O₂ pressure. No osteogenic medium was used. Eight different cultures were performed at each time point under each O₂ pressure condition. Cell adhesion, proliferation, and differentiation over the biomaterial were evaluated at 7, 13, 18, and 23 days of culture. Cell adhesion was determined by light microscopy, proliferation by DNA quantification, and osteogenic differentiation by alkaline phosphatase (ALP) activity analysis. DPSC adhered to β-TCP with both O₂ conditions. Cell proliferation was found from day 7 of culture. Higher values were recorded at 3% O₂ in each time point. Statistically significant differences were recorded at 23 days of culture (P = .033). ALP activity was not detectable at 7 days. There was, however, an increase in ALP activity over time in both groups. At 13, 18, and 23 days of culture, higher ALP activity was recorded under 3% O₂ pressure. Statistical differences were found at day 23 (P = .014). DPSC display capacity of adhering to β-TCP under 3% or 21% O₂ pressure conditions. Cell proliferation on β-TCP phosphate is significantly higher at 3% than at 21% O₂ pressure, the most frequently used O₂ tension. β-TCP can itself promote osteogenic differentiation of DPSC and is enhanced under 3% O₂ compared with 21%.

Genome-wide detection of natural selection in African Americans pre- and post-admixture

PubMed Central

Jin, Wenfei; Xu, Shuhua; Wang, Haifeng; Yu, Yongguo; Shen, Yiping; Wu, Bailin; Jin, Li

2012-01-01

It is particularly meaningful to investigate natural selection in African Americans (AfA) due to the high mortality their African ancestry has experienced in history. In this study, we examined 491,526 autosomal single nucleotide polymorphisms (SNPs) genotyped in 5210 individuals and conducted a genome-wide search for selection signals in 1890 AfA. Several genomic regions showing an excess of African or European ancestry, which were considered the footprints of selection since population admixture, were detected based on a commonly used approach. However, we also developed a new strategy to detect natural selection both pre- and post-admixture by reconstructing an ancestral African population (AAF) from inferred African components of ancestry in AfA and comparing it with indigenous African populations (IAF). Interestingly, many selection-candidate genes identified by the new approach were associated with AfA-specific high-risk diseases such as prostate cancer and hypertension, suggesting an important role these disease-related genes might have played in adapting to a new environment. CD36 and HBB, whose mutations confer a degree of protection against malaria, were also located in the highly differentiated regions between AAF and IAF. Further analysis showed that the frequencies of alleles protecting against malaria in AAF were lower than those in IAF, which is consistent with the relaxed selection pressure of malaria in the New World. There is no overlap between the top candidate genes detected by the two approaches, indicating the different environmental pressures AfA experienced pre- and post-population admixture. We suggest that the new approach is reasonably powerful and can also be applied to other admixed populations such as Latinos and Uyghurs. PMID:22128132

Cyclooxygenases 1 and 2 Differentially Regulate Blood Pressure and Cerebrovascular Responses to Acute and Chronic Intermittent Hypoxia: Implications for Sleep Apnea

PubMed Central

Beaudin, Andrew E.; Pun, Matiram; Yang, Christina; Nicholl, David D. M.; Steinback, Craig D.; Slater, Donna M.; Wynne‐Edwards, Katherine E.; Hanly, Patrick J.; Ahmed, Sofia B.; Poulin, Marc J.

2014-01-01

Background Obstructive sleep apnea (OSA) is associated with increased risk of cardiovascular and cerebrovascular disease resulting from intermittent hypoxia (IH)‐induced inflammation. Cyclooxygenase (COX)‐formed prostanoids mediate the inflammatory response, and regulate blood pressure and cerebral blood flow (CBF), but their role in blood pressure and CBF responses to IH is unknown. Therefore, this study's objective was to determine the role of prostanoids in cardiovascular and cerebrovascular responses to IH. Methods and Results Twelve healthy, male participants underwent three, 6‐hour IH exposures. For 4 days before each IH exposure, participants ingested a placebo, indomethacin (nonselective COX inhibitor), or Celebrex® (selective COX‐2 inhibitor) in a double‐blind, randomized, crossover study design. Pre‐ and post‐IH blood pressure, CBF, and urinary prostanoids were assessed. Additionally, blood pressure and urinary prostanoids were assessed in newly diagnosed, untreated OSA patients (n=33). Nonselective COX inhibition increased pre‐IH blood pressure (P≤0.04) and decreased pre‐IH CBF (P=0.04) while neither physiological variable was affected by COX‐2 inhibition (P≥0.90). Post‐IH, MAP was elevated (P≤0.05) and CBF was unchanged with placebo and nonselective COX inhibition. Selective COX‐2 inhibition abrogated the IH‐induced MAP increase (P=0.19), but resulted in lower post‐IH CBF (P=0.01). Prostanoids were unaffected by IH, except prostaglandin E2 was elevated with the placebo (P=0.02). Finally, OSA patients had elevated blood pressure (P≤0.4) and COX‐1 formed thromboxane A2 concentrations (P=0.02). Conclusions COX‐2 and COX‐1 have divergent roles in modulating vascular responses to acute and chronic IH. Moreover, COX‐1 inhibition may mitigate cardiovascular and cerebrovascular morbidity in OSA. Clinical Trial Registration URL: www.clinicaltrials.gov. Unique identifier: NCT01280006 PMID:24815497

Modified Biot-Gassmann theory for calculating elastic velocities for unconsolidated and consolidated sediments

USGS Publications Warehouse

Lee, M.W.

2002-01-01

The classical Biot-Gassmann theory (BGT) generally overestimates shear-wave velocities of water-saturated sediments. To overcome this problem, a new theory is developed based on BGT and on the velocity ratio as a function of G(1 - ??)n, where ?? is porosity and n and G are constants. Based on laboratory data measured at ultrasonic frequencies, parameters for the new formulation are derived. This new theory is extended to include the effect of differential pressure and consolidation on the velocity ratio by making n a function of differential pressure and the rate of porosity reduction with respect to differential pressure. A scale G is introduced to compensate for discrepancies between measured and predicted velocities, mainly caused by the presence of clay in the matrix. As differential pressure increases and the rate of porosity reduction with respect to differential pressure decreases, the exponent n decreases and elastic velocities increase. Because velocity dispersion is not considered, this new formula is optimum for analyzing velocities measured at ultrasonic frequencies or for sediments having low dispersion characteristics such as clean sandstone with high permeability and lack of grain-scale local flow. The new formula is applied to predict velocities from porosity or from porosity and P-wave velocity and is in good agreement with laboratory and well log data. ?? 2004 Kluwer Academic Publishers. Printed in the Netherlands.

System and method for bidirectional flow and controlling fluid flow in a conduit

DOEpatents

Ortiz, Marcos German

1999-01-01

A system for measuring bidirectional flow, including backflow, of fluid in a conduit. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit.

Consistent Selection towards Low Activity Phenotypes When Catchability Depends on Encounters among Human Predators and Fish

PubMed Central

Alós, Josep; Palmer, Miquel; Arlinghaus, Robert

2012-01-01

Together with life-history and underlying physiology, the behavioural variability among fish is one of the three main trait axes that determines the vulnerability to fishing. However, there are only a few studies that have systematically investigated the strength and direction of selection acting on behavioural traits. Using in situ fish behaviour revealed by telemetry techniques as input, we developed an individual-based model (IBM) that simulated the Lagrangian trajectory of prey (fish) moving within a confined home range (HR). Fishers exhibiting various prototypical fishing styles targeted these fish in the model. We initially hypothesised that more active and more explorative individuals would be systematically removed under all fished conditions, in turn creating negative selection differentials on low activity phenotypes and maybe on small HR. Our results partly supported these general predictions. Standardised selection differentials were, on average, more negative on HR than on activity. However, in many simulation runs, positive selection pressures on HR were also identified, which resulted from the stochastic properties of the fishes’ movement and its interaction with the human predator. In contrast, there was a consistent negative selection on activity under all types of fishing styles. Therefore, in situations where catchability depends on spatial encounters between human predators and fish, we would predict a consistent selection towards low activity phenotypes and have less faith in the direction of the selection on HR size. Our study is the first theoretical investigation on the direction of fishery-induced selection of behaviour using passive fishing gears. The few empirical studies where catchability of fish was measured in relation to passive fishing techniques, such as gill-nets, traps or recreational fishing, support our predictions that fish in highly exploited situations are, on average, characterised by low swimming activity, stemming, in part, from negative selection on swimming activity. PMID:23110164

49 CFR 173.167 - Consumer commodities.

Code of Federal Regulations, 2014 CFR

2014-10-01

...-toxic aerosols only), Class 3 (Packing Group II and III only), Division 6.1 (Packing Group III only.... Additionally, except for the pressure differential requirements in § 173.27(c), the requirements of § 173.27 do... appropriate, in accordance with subpart E of part 172 of this subchapter; and (2) Pressure differential...

Evaluation of AHRQ's on-time pressure ulcer prevention program: a facilitator-assisted clinical decision support intervention for nursing homes.

PubMed

Olsho, Lauren E W; Spector, William D; Williams, Christianna S; Rhodes, William; Fink, Rebecca V; Limcangco, Rhona; Hurd, Donna

2014-03-01

Pressure ulcers present serious health and economic consequences for nursing home residents. The Agency for Healthcare Research & Quality, in partnership with the New York State Department of Health, implemented the pressure ulcer module of On-Time Quality Improvement for Long Term Care (On-Time), a clinical decision support intervention to reduce pressure ulcer incidence rates. To evaluate the effectiveness of the On-Time program in reducing the rate of in-house-acquired pressure ulcers among nursing home residents. We employed an interrupted time-series design to identify impacts of 4 core On-Time program components on resident pressure ulcer incidence in 12 New York State nursing homes implementing the intervention (n=3463 residents). The sample was purposively selected to include nursing homes with high baseline prevalence and incidence of pressure ulcers and high motivation to reduce pressure ulcers. Differential timing and sequencing of 4 core On-Time components across intervention nursing homes and units enabled estimation of separate impacts for each component. Inclusion of a nonequivalent comparison group of 13 nursing homes not implementing On-Time (n=2698 residents) accounts for potential mean-reversion bias. Impacts were estimated via a random-effects Poisson model including resident-level and facility-level covariates. We find a large and statistically significant reduction in pressure ulcer incidence associated with the joint implementation of 4 core On-Time components (incidence rate ratio=0.409; P=0.035). Impacts vary with implementation of specific component combinations. On-Time implementation is associated with sizable reductions in pressure ulcer incidence.

Low-Pressure Generator Makes Cleanrooms Cleaner

NASA Technical Reports Server (NTRS)

2005-01-01

Scientists at NASA's Kennedy Space Center work in cleanrooms: laboratories with high degrees of cleanliness provided by strict control of particles such as dust, lint, or human skin. They are contaminant-free facilities, where the air is repeatedly filtered, and surfaces are smooth to prevent particles from getting lodged. Technicians working in these environments wear specially designed cleanroom "bunny suits" and booties over their street clothes, as well as gloves and face masks to avoid any contamination that may be imparted from the outside world. Even normal paper is not allowed in cleanrooms, only cleanroom low-particulate paper. These are sensitive environments where precision work, like the production of silicon chips or hard disk drives, is performed. Often in cleanrooms, positive air pressure is used to force particles outside of the isolated area. The air pressure in the Kennedy cleanrooms is monitored using high-accuracy, low-differential pressure transducers that require periodic calibration. Calibration of the transducers is a tricky business. In prior years, the analysis was performed by sending the transducers to the Kennedy Standards Laboratory, where a very expensive cross-floated, labor- intensive, dead-weight test was conducted. In the early 1990s, scientists at Kennedy determined to develop a technique and find equipment to perform qualification testing on new low-differential pressure transducers in an accurate, cost-effective manner onsite, without requiring an environmentally controlled room. They decided to use the highly accurate, cost-effective Setra Model C264 as the test transducer. For qualification testing of the Setra, though, a portable, lower-cost calibrator was needed that could control the differential pressure to a high degree of resolution and transfer the accuracy of the Standards Laboratory testing to the qualification testing. The researchers decided that, to generate the low-differential pressure setpoints needed for qualification testing, very small gas volume changes could be made against the test article, and a corresponding pressure change would be detected by a pressure standard. This allowed the researchers to recreate cleanroom air pressure settings without the use of a cleanroom. Thus was born the low-differential pressure generator. In 1993, a prototype was developed using a pair of PVC tanks, a volume controller, and a 1-pound-per-square-inch pressure standard. By 1995, the prototype was perfected into the unit that is still used today.

Continuous hydrostatic pressure induces differentiation phenomena in chondrocytes mediated by changes in polycystins, SOX9, and RUNX2.

PubMed

Karamesinis, Konstantinos; Spyropoulou, Anastasia; Dalagiorgou, Georgia; Katsianou, Maria A; Nokhbehsaim, Marjan; Memmert, Svenja; Deschner, James; Vastardis, Heleni; Piperi, Christina

2017-01-01

The present study aimed to investigate the long-term effects of hydrostatic pressure on chondrocyte differentiation, as indicated by protein levels of transcription factors SOX9 and RUNX2, on transcriptional activity of SOX9, as determined by pSOX9 levels, and on the expression of polycystin-encoding genes Pkd1 and Pkd2. ATDC5 cells were cultured in insulin-supplemented differentiation medium (ITS) and/or exposed to 14.7 kPa of hydrostatic pressure for 12, 24, 48, and 96 h. Cell extracts were assessed for SOX9, pSOX9, and RUNX2 using western immunoblotting. The Pkd1 and Pkd2 mRNA levels were detected by real-time PCR. Hydrostatic pressure resulted in an early drop in SOX9 and pSOX9 protein levels at 12 h followed by an increase from 24 h onwards. A reverse pattern was followed by RUNX2, which reached peak levels at 24 h of hydrostatic pressure-treated chondrocytes in ITS culture. Pkd1 and Pkd2 mRNA levels increased at 24 h of combined hydrostatic pressure and ITS treatment, with the latter remaining elevated up to 96 h. Our data indicate that long periods of continuous hydrostatic pressure stimulate chondrocyte differentiation through a series of molecular events involving SOX9, RUNX2, and polycystins-1, 2, providing a theoretical background for functional orthopedic mechanotherapies.

Effects of pressure ulcer classification system education programme on knowledge and visual differential diagnostic ability of pressure ulcer classification and incontinence-associated dermatitis for clinical nurses in Korea.

PubMed

Lee, Yun Jin; Kim, Jung Yoon

2016-03-01

The objective of this study was to evaluate the effect of pressure ulcer classification system education on clinical nurses' knowledge and visual differential diagnostic ability of pressure ulcer (PU) classification and incontinence-associated dermatitis (IAD). One group pre and post-test was used. A convenience sample of 407 nurses, participating in PU classification education programme of continuing education, were enrolled. The education programme was composed of a 50-minute lecture on PU classification and case-studies. The PU Classification system and IAD knowledge test (PUCS-KT) and visual differential diagnostic ability tool (VDDAT), consisting of 21 photographs including clinical information were used. Paired t-test was performed using SPSS/WIN 20.0. The overall mean difference of PUCS-KT (t = -11·437, P<0·001) and VDDAT (t = -21·113, P<0·001) was significantly increased after PU classification education. Overall understanding of six PU classification and IAD after education programme was increased, but lacked visual differential diagnostic ability regarding Stage III PU, suspected deep tissue injury (SDTI), and Unstageable. Continuous differentiated education based on clinical practice is needed to improve knowledge and visual differential diagnostic ability for PU classification, and comparison experiment study is required to examine effects of education programmes. © 2016 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor.

PubMed

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-07-22

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations.

Passive Resistor Temperature Compensation for a High-Temperature Piezoresistive Pressure Sensor

PubMed Central

Yao, Zong; Liang, Ting; Jia, Pinggang; Hong, Yingping; Qi, Lei; Lei, Cheng; Zhang, Bin; Li, Wangwang; Zhang, Diya; Xiong, Jijun

2016-01-01

The main limitation of high-temperature piezoresistive pressure sensors is the variation of output voltage with operating temperature, which seriously reduces their measurement accuracy. This paper presents a passive resistor temperature compensation technique whose parameters are calculated using differential equations. Unlike traditional experiential arithmetic, the differential equations are independent of the parameter deviation among the piezoresistors of the microelectromechanical pressure sensor and the residual stress caused by the fabrication process or a mismatch in the thermal expansion coefficients. The differential equations are solved using calibration data from uncompensated high-temperature piezoresistive pressure sensors. Tests conducted on the calibrated equipment at various temperatures and pressures show that the passive resistor temperature compensation produces a remarkable effect. Additionally, a high-temperature signal-conditioning circuit is used to improve the output sensitivity of the sensor, which can be reduced by the temperature compensation. Compared to traditional experiential arithmetic, the proposed passive resistor temperature compensation technique exhibits less temperature drift and is expected to be highly applicable for pressure measurements in harsh environments with large temperature variations. PMID:27455271

Extreme reversed sexual dichromatism in a bird without sex role reversal.

PubMed

Heinsohn, Robert; Legge, Sarah; Endler, John A

2005-07-22

Brilliant plumage is typical of male birds, reflecting differential enhancement of male traits when females are the limiting sex. Brighter females are thought to evolve exclusively in response to sex role reversal. The striking reversed plumage dichromatism of Eclectus roratus parrots does not fit this pattern. We quantify plumage color in this species and show that very different selection pressures are acting on males and females. Male plumage reflects a compromise between the conflicting requirements for camouflage from predators while foraging and conspicuousness during display. Females are liberated from the need for camouflage but compete for rare nest hollows.

ROLE OF PRESSURE IN SMECTITE DEHYDRATION - EFFECTS ON GEOPRESSURE AND SMECTITE-TO-ILLITE TRANSFORMATION.

USGS Publications Warehouse

Colten-Bradley, Virginia

1987-01-01

Evaluation of the effects of pressure on the temperature of interlayer water loss (dehydration) by smectites under diagenetic conditions indicates that smectites are stable as hydrated phases in the deep subsurface. Hydraulic and differential pressure conditions affect dehydration differently. The temperature of dehydration increase with pore fluid pressure and interlayer water density. The temperatures of dehydration increase with pore fluid pressure and interlayer water density. The temperatures of dehydration under differential-presssure conditions are inversely related to pressure and interlayer water density. The model presented assumes the effects of pore fluid composition and 2:1 layer reactivity to be negligible. Agreement between theoretical and experimental results validate this assumption. Additional aspects of the subject are discussed.

Variable pressure ionization detector for gas chromatography

DOEpatents

Buchanan, Michelle V.; Wise, Marcus B.

1988-01-01

Method and apparatus for differentiating organic compounds based on their electron affinity. An electron capture detector cell (ECD) is operated at pressures ranging from atmospheric to less than 1 torr. Through variation of the pressure within the ECD cell, the organic compounds are induced to either capture or emit electrons. Differentiation of isomeric compounds can be obtianed when, at a given pressure, one isomer is in the emission mode and the other is in the capture mode. Output of the ECD is recorded by chromatogram. The invention also includes a method for obtaining the zero-crossing pressure of a compound, defined as the pressure at which the competing emission and capture reactions are balanced and which may be correlated to the electron affinity of a compound.

Spatial Niche Segregation of Sympatric Stone Marten and Pine Marten--Avoidance of Competition or Selection of Optimal Habitat?

PubMed

Wereszczuk, Anna; Zalewski, Andrzej

2015-01-01

Coexistence of ecologically similar species relies on differences in one or more dimensions of their ecological niches, such as space, time and resources in diel and/or seasonal scales. However, niche differentiation may result from other mechanisms such as avoidance of high predation pressure, different adaptations or requirements of ecologically similar species. Stone marten (Martes foina) and pine marten (Martes martes) occur sympatrically over a large area in Central Europe and utilize similar habitats and food, therefore it is expected that their coexistence requires differentiation in at least one of their niche dimensions or the mechanisms through which these dimensions are used. To test this hypothesis, we used differences in the species activity patterns and habitat selection, estimated with a resource selection function (RSF), to predict the relative probability of occurrence of the two species within a large forest complex in the northern geographic range of the stone marten. Stone martens were significantly heavier, have a longer body and a better body condition than pine martens. We found weak evidence for temporal niche segregation between the species. Stone and pine martens were both primarily nocturnal, but pine martens were active more frequently during the day and significantly reduced the duration of activity during autumn-winter. Stone and pine martens utilized different habitats and almost completely separated their habitat niches. Stone marten strongly preferred developed areas and avoided meadows and coniferous or deciduous forests. Pine marten preferred deciduous forest and small patches covered by trees, and avoided developed areas and meadows. We conclude that complete habitat segregation of the two marten species facilitates sympatric coexistence in this area. However, spatial niche segregation between these species was more likely due to differences in adaptation to cold climate, avoidance of high predator pressure and/or food preferences by both species than competitive interaction between them.

Pressure-accelerated azide-alkyne cycloaddition: micro capillary versus autoclave reactor performance.

PubMed

Borukhova, Svetlana; Seeger, Andreas D; Noël, Timothy; Wang, Qi; Busch, Markus; Hessel, Volker

2015-02-01

Pressure effects on regioselectivity and yield of cycloaddition reactions have been shown to exist. Nevertheless, high pressure synthetic applications with subsequent benefits in the production of natural products are limited by the general availability of the equipment. In addition, the virtues and limitations of microflow equipment under standard conditions are well established. Herein, we apply novel-process-window (NPWs) principles, such as intensification of intrinsic kinetics of a reaction using high temperature, pressure, and concentration, on azide-alkyne cycloaddition towards synthesis of Rufinamide precursor. We applied three main activation methods (i.e., uncatalyzed batch, uncatalyzed flow, and catalyzed flow) on uncatalyzed and catalyzed azide-alkyne cycloaddition. We compare the performance of two reactors, a specialized autoclave batch reactor for high-pressure operation up to 1800 bar and a capillary flow reactor (up to 400 bar). A differentiated and comprehensive picture is given for the two reactors and the three methods of activation. Reaction speedup and consequent increases in space-time yields is achieved, while the process window for favorable operation to selectively produce Rufinamide precursor in good yields is widened. The best conditions thus determined are applied to several azide-alkyne cycloadditions to widen the scope of the presented methodology. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Amino Acids That Centrally Influence Blood Pressure and Regional Blood Flow in Conscious Rats

PubMed Central

Takemoto, Yumi

2012-01-01

Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken. PMID:22690328

Rowan Gorilla I rigged up, heads for eastern Canada

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

Not Available

1984-03-01

Designed to operate in very hostile offshore environments, the first of the Rowan Gorilla class of self-elevating drilling rigs has been towed to its drilling assignment offshore Nova Scotia. About 40% larger than other jackups, these rigs can operate in 300 ft of water, drilling holes as deep as 30,000 ft. They also feature unique high-pressure and solids control systems that are expected to improve drilling procedures and efficiencies. A quantitative formation pressure evaluation program for the Hewlett-Packard HP-41 handheld calculator computes formation pressures by three independent methods - the corrected d exponent, Bourgoyne and Young, and normalized penetration ratemore » techniques for abnormal pressure detection and computation. Based on empirically derived drilling rate equations, each of the methods can be calculated separately, without being dependent on or influenced by the results or stored data from the other two subprograms. The quantitative interpretation procedure involves establishing a normal drilling rate trend and calculating the pore pressure from the magnitude of the drilling rate trend or plotting parameter increases above the trend line. Mobil's quick, accurate program could aid drilling operators in selecting the casing point, minimizing differential sticking, maintaining the proper mud weights to avoid kicks and lost circulation, and maximizing penetration rates.« less

Stretchable energy-harvesting tactile electronic skin capable of differentiating multiple mechanical stimuli modes.

PubMed

Park, Steve; Kim, Hyunjin; Vosgueritchian, Michael; Cheon, Sangmo; Kim, Hyeok; Koo, Ja Hoon; Kim, Taeho Roy; Lee, Sanghyo; Schwartz, Gregory; Chang, Hyuk; Bao, Zhenan

2014-11-19

The first stretchable energy-harvesting electronic-skin device capable of differentiating and generating energy from various mechanical stimuli, such as normal pressure, lateral strain, bending, and vibration, is presented. A pressure sensitivity of 0.7 kPa(-1) is achieved in the pressure region <1 kPa with power generation of tens of μW cm(-2) from a gentle finger touch. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Study on Temperature and Synthetic Compensation of Piezo-Resistive Differential Pressure Sensors by Coupled Simulated Annealing and Simplex Optimized Kernel Extreme Learning Machine

PubMed Central

Li, Ji; Hu, Guoqing; Zhou, Yonghong; Zou, Chong; Peng, Wei; Alam SM, Jahangir

2017-01-01

As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear measuring characteristics of the piezo-resistive differential pressure sensor, compensation actions should synthetically consider these two aspects. Advantages such as nonlinear approximation capability, highly desirable generalization ability and computational efficiency make the kernel extreme learning machine (KELM) a practical approach for this critical task. Since the KELM model is intrinsically sensitive to the regularization parameter and the kernel parameter, a searching scheme combining the coupled simulated annealing (CSA) algorithm and the Nelder-Mead simplex algorithm is adopted to find an optimal KLEM parameter set. A calibration experiment at different working pressure levels was conducted within the temperature range to assess the proposed method. In comparison with other compensation models such as the back-propagation neural network (BP), radius basis neural network (RBF), particle swarm optimization optimized support vector machine (PSO-SVM), particle swarm optimization optimized least squares support vector machine (PSO-LSSVM) and extreme learning machine (ELM), the compensation results show that the presented compensation algorithm exhibits a more satisfactory performance with respect to temperature compensation and synthetic compensation problems. PMID:28422080

Study on Temperature and Synthetic Compensation of Piezo-Resistive Differential Pressure Sensors by Coupled Simulated Annealing and Simplex Optimized Kernel Extreme Learning Machine.

PubMed

Li, Ji; Hu, Guoqing; Zhou, Yonghong; Zou, Chong; Peng, Wei; Alam Sm, Jahangir

2017-04-19

As a high performance-cost ratio solution for differential pressure measurement, piezo-resistive differential pressure sensors are widely used in engineering processes. However, their performance is severely affected by the environmental temperature and the static pressure applied to them. In order to modify the non-linear measuring characteristics of the piezo-resistive differential pressure sensor, compensation actions should synthetically consider these two aspects. Advantages such as nonlinear approximation capability, highly desirable generalization ability and computational efficiency make the kernel extreme learning machine (KELM) a practical approach for this critical task. Since the KELM model is intrinsically sensitive to the regularization parameter and the kernel parameter, a searching scheme combining the coupled simulated annealing (CSA) algorithm and the Nelder-Mead simplex algorithm is adopted to find an optimal KLEM parameter set. A calibration experiment at different working pressure levels was conducted within the temperature range to assess the proposed method. In comparison with other compensation models such as the back-propagation neural network (BP), radius basis neural network (RBF), particle swarm optimization optimized support vector machine (PSO-SVM), particle swarm optimization optimized least squares support vector machine (PSO-LSSVM) and extreme learning machine (ELM), the compensation results show that the presented compensation algorithm exhibits a more satisfactory performance with respect to temperature compensation and synthetic compensation problems.

Multiple mating and its relationship to alternative modes of gestation in male-pregnant versus female-pregnant fish species

PubMed Central

Avise, John C.; Liu, Jin-Xian

2010-01-01

We construct a verbal and graphical theory (the “fecundity-limitation hypothesis”) about how constraints on the brooding space for embryos probably truncate individual fecundity in male-pregnant and female-pregnant species in ways that should differentially influence selection pressures for multiple mating by males or by females. We then review the empirical literature on genetically deduced rates of multiple mating by the embryo-brooding parent in various fish species with three alternative categories of pregnancy: internal gestation by males, internal gestation by females, and external gestation (in nests) by males. Multiple mating by the brooding gender was common in all three forms of pregnancy. However, rates of multiple mating as well as mate numbers for the pregnant parent averaged higher in species with external as compared with internal male pregnancy, and also for dams in female-pregnant species versus sires in male-pregnant species. These outcomes are all consistent with the theory that different types of pregnancy have predictable consequences for a parent's brood space, its effective fecundity, its opportunities and rewards for producing half-sib clutches, and thereby its exposure to selection pressures for seeking multiple mates. Overall, we try to fit these fecundity-limitation phenomena into a broader conceptual framework for mating-system evolution that also includes anisogamy, sexual-selection gradients, parental investment, and other selective factors that can influence the relative proclivities of males versus females to seek multiple sexual partners. PMID:20956296

Pressure deformation of tires using differential stiffness for triangular solid-of-revolution elements

NASA Technical Reports Server (NTRS)

Chen, C. H. S.

1975-01-01

The derivation is presented of the differential stiffness for triangular solid of revolution elements. The derivation takes into account the element rigid body rotation only, the rotation being about the circumferential axis. Internal pressurization of a pneumatic tire is used to illustrate the application of this feature.

Attached biofilms and suspended aggregates are distinct microbial lifestyles emanating from differing hydraulics.

PubMed

Niederdorfer, Robert; Peter, Hannes; Battin, Tom J

2016-10-03

Small-scale hydraulics affects microbial behaviour at the cell level 1 , trophic interactions in marine aggregates 2 and the physical structure and function of stream biofilms 3,4 . However, it remains unclear how hydraulics, predictably changing from small streams to large rivers, impacts the structure and biodiversity of complex microbial communities in these ecosystems. Here, we present experimental evidence unveiling hydraulics as a hitherto poorly recognized control of microbial lifestyle differentiation in fluvial ecosystems. Exposing planktonic source communities from stream and floodplain ecosystems to different hydraulic environments revealed strong selective hydraulic pressures but only minor founder effects on the differentiation of attached biofilms and suspended aggregates and their biodiversity dynamics. Key taxa with a coherent phylogenetic underpinning drove this differentiation. Only a few resident and phylogenetically related taxa formed the backbone of biofilm communities, whereas numerous resident taxa characterized aggregate communities. Our findings unveil fundamental differences between biofilms and aggregates and build the basis for a mechanistic understanding of how hydraulics drives the distribution of microbial diversity along the fluvial continuum 5-7 .

Reconstituting the Evolutionary History of Cronobacter Driven by Differentiated CRISPR Activity.

PubMed

Zeng, Haiyan; Zhang, Jumei; Wu, Qingping; He, Wenjing; Wu, Haoming; Ye, Yingwang; Li, Chengsi; Ling, Na; Chen, Moutong; Wang, Juan; Cai, Shuzhen; Lei, Tao; Ding, Yu; Xue, Liang

2018-03-09

Cronobacter strains harboring the CRISPR-Cas system are important foodborne pathogens causing serious neonatal infections. However, the specific role of the CRISPR-Cas system in bacterial evolution remains relatively unexplored. In this study, we investigated the impact of CRISPR-Cas in Cronobacter evolution and obtained 137 new whole-genome sequences of Cronobacter by next-generation sequencing technology. Among the strains examined (n=240), 90.6% (193/213) of prevalent species Cronobacter sakazakii , Cronobacter malonaticus , and Cronobacter dublinensis strains had intact CRISPR-Cas systems. Two rare species, Cronobacter condimenti (n=2) and Cronobacter universalis (n=6), lacked and preserved the CRISPR-Cas system at a low frequency (1/6), respectively. These results suggest that the presence of one CRISPR-Cas system in Cronobacter is important for the species to maintain genome homeostasis for survival. The Cronobacter ancestral strain was likely to harbored both subtype I-E and I-F CRISPR-Cas systems, during the long evolutionary process, subtype I-E was retained, while subtype I-F selectively degenerated in Cronobacter species and was even lost in the major Cronobacter pathovars. Moreover, significantly higher CRISPR activity was observed in plant-associated species C. dublinensis than in the virulence-related species C. sakazakii and C. malonaticus Similar spacers of CRISPR arrays were rarely found among species, suggesting intensive change through adaptive acquisition and loss. Differentiated CRISPR activity appears to be the product of environmental selective pressure and might contribute to the bidirectional divergence and speciation of Cronobacter IMPORTANCE This study reports the evolutionary history of Cronobacter under the selective pressure of the CRISPR-Cas system. One CRISPR-Cas system in Cronobacter is important for maintaining genome homeostasis, whereas two types of systems may be redundant and not conducive for acquiring beneficial DNA for environmental adaption and pathogenicity. Differentiated CRISPR activity has contributed to the bidirectional divergence and genetic diversity of Cronobacter This perspective makes a significant contribution to the literature by providing new insights into CRISPR-Cas systems in general, while further expanding the roles of CRISPR beyond conferring adaptive immunity and demonstrating a link to adaptation and species divergence in a genus. Moreover, our study provides new insights into the balance between genome homeostasis and the uptake of beneficial DNA related to CRISPR-based activity in the evolution of Cronobacter . Copyright © 2018 American Society for Microbiology.

System and method for bidirectional flow and controlling fluid flow in a conduit

DOEpatents

Ortiz, M.G.

1999-03-23

A system for measuring bidirectional flow, including backflow, of fluid in a conduit is disclosed. The system utilizes a structural mechanism to create a pressure differential in the conduit. Pressure sensors are positioned upstream from the mechanism, at the mechanism, and downstream from the mechanism. Data from the pressure sensors are transmitted to a microprocessor or computer, and pressure differential detected between the pressure sensors is then used to calculate the backflow. Control signals may then be generated by the microprocessor or computer to shut off valves located in the conduit, upon the occurrence of backflow, or to control flow, total material dispersed, etc. in the conduit. 3 figs.

Migration rates and formation injectivity to determine containment time scales of sequestered carbon dioxide

USGS Publications Warehouse

Burke, Lauri

2012-01-01

Additionally, this research establishes a methodology to calculate the injectivity of a target formation. Because injectivity describes the pressure increase due to the introduction of fluids into a formation, the relevant application of injectivity is to determine the pressure increase, due to an injection volume and flow rate, that will induce fractures in the reservoir rocks. This quantity is defined mathematically as the maximum pressure differential between the hydrostatic gradient and the fracture gradient of the target formation. Injectivity is mathematically related to the maximum pressure differential of the formation, and can be used to determine the upper limit for the pressure increase that an injection target can withstand before fracturing.

The close relationship between estimated divergent selection and observed differentiation supports the selective origin of a marine snail hybrid zone.

PubMed

Cruz, R; Vilas, C; Mosquera, J; García, C

2004-11-01

To study the role of divergent selection in the differentiation of the two morphs in a hybrid zone of the intertidal snail Littorina saxatilis, we compared the strength of the divergent selection acting on a series of shell characters (as estimated by the viability of snails in a reciprocal transplant experiment) with the contribution of these characters to the phenotypic differences between the morphs. We found a close correlation between selection and differentiation, which suggests a cause-effect relationship, i.e. that all present differentiation is the result of past divergent selection. In addition, divergent selection was a very important component of the total natural selection acting on shell measures. These novel results support previous evidence, based on allozyme analysis, of a parapatric origin for this hybrid zone. We discuss possible limitations of this interpretation and the circumstances under which allopatric differentiation would produce the same results. Phenotypic analysis of divergent selection may be a useful method of investigating the evolutionary mechanisms involved in differentiation processes.

Intraspecific variation in a generalist herbivore accounts for differential induction and impact of host plant defences

PubMed Central

Kant, Merijn R; Sabelis, Maurice W; Haring, Michel A; Schuurink, Robert C

2007-01-01

Plants and herbivores are thought to be engaged in a coevolutionary arms race: rising frequencies of plants with anti-herbivore defences exert pressure on herbivores to resist or circumvent these defences and vice versa. Owing to its frequency-dependent character, the arms race hypothesis predicts that herbivores exhibit genetic variation for traits that determine how they deal with the defences of a given host plant phenotype. Here, we show the existence of distinct variation within a single herbivore species, the spider mite Tetranychus urticae, in traits that lead to resistance or susceptibility to jasmonate (JA)-dependent defences of a host plant but also in traits responsible for induction or repression of JA defences. We characterized three distinct lines of T. urticae that differentially induced JA-related defence genes and metabolites while feeding on tomato plants (Solanum lycopersicum). These lines were also differently affected by induced JA defences. The first line, which induced JA-dependent tomato defences, was susceptible to those defences; the second line also induced JA defences but was resistant to them; and the third, although susceptible to JA defences, repressed induction. We hypothesize that such intraspecific variation is common among herbivores living in environments with a diversity of plants that impose diverse selection pressure. PMID:18055390

Investigation of the effects of extravehicular activity (EVA) gloves on performance

NASA Technical Reports Server (NTRS)

Bishu, Ram R.; Klute, Glenn

1993-01-01

The objective was to assess the effects of extravehicular activity (EVA) gloves at different pressures on human hand capabilities. A factorial experiment was performed in which three types of EVA gloves were tested at five pressure differentials. The independent variables tested in this experiment were gender, glove type, pressure differential, and glove make. Six subjects participated in an experiment where a number of dexterity measures, namely time to tie a rope, and the time to assemble a nut and bolt were recorded. Tactility was measured through a two point discrimination test. The results indicate that with EVA gloves strength is reduced by nearly 50 percent, there is a considerable reduction in dexterity, performance decrements increase with increasing pressure differential, and some interesting gender glove interactions were observed, some of which may have been due to the extent (or lack of) fit of the glove to the hand. The implications for the designer are discussed.

Hydrologic regimes as potential drivers of morphologic divergence in fish

USGS Publications Warehouse

Bruckerhoff, Lindsey; Magoulick, Daniel D.

2017-01-01

Fishes often exhibit phenotypic divergence across gradients of abiotic and biotic selective pressures. In streams, many of the known selective pressures driving phenotypic differentiation are largely influenced by hydrologic regimes. Because flow regimes drive so many attributes of lotic systems, we hypothesized fish exhibit phenotypic divergence among streams with different flow regimes. We used a comparative field study to investigate the morphological divergence of Campostoma anomalom (central stonerollers) among streams characterized by highly variable, intermittent flow regimes and streams characterized by relatively stable, groundwater flow regimes. We also conducted a mesocosm experiment to compare the plastic effects of one component of flow regimes, water velocity, on morphology of fish from different flow regimes. We observed differences in shape between flow regimes likely driven by differences in allometric growth patterns. Although we observed differences in morphology across flow regimes in the field, C. anomalum did not exhibit morphologic plasticity in response to water velocity alone. This study contributes to the understanding of how complex environmental factors drive phenotypic divergence and may provide insight into the evolutionary consequences of disrupting natural hydrologic patterns, which are increasingly threatened by climate change and anthropogenic alterations.

Modulation of B16-BL6 murine melanoma metastatic phenotype by tyrosine and phenylalanine restriction in the absence of host selection pressures.

PubMed

Elstad, C A; Meadows, G G

1993-01-01

We previously showed that restriction of tyrosine (Tyr) and phenylalanine (Phe) in vivo dramatically suppresses the metastatic phenotype of B16-BL6 (BL6) murine melanoma. Present results indicate a direct effect of Tyr and Phe restriction on the tumor in the absence of host selection pressures. Lung colonizing ability of BL6 is dramatically suppressed after one passage in vitro in media containing low levels of Tyr and Phe. This antimetastatic effect is immediate, stable for at least 5 in vitro passages in Tyr and Phe restricted media, and evident event after levels of Tyr and Phe are restored to normal. Heterogeneity for lung colonizing ability is suppressed, as evidence by fewer tumor colonies formed by clones following i.v. inoculation into mice fed normal diet. This suppression of BL6 metastatic phenotype is not due to differential clearance and retention in the lung or to decreased growth, but is specific for these two amino acids. As the mechanism(s) for the antitumor effects of Tyr and Phe restriction are detailed, the relevance of Tyr and Phe restriction as an early adjuvant to effective cancer treatment can be explored.

Modeling population dynamics of mitochondria in mammalian cells

NASA Astrophysics Data System (ADS)

Kornick, Kellianne; Das, Moumita

Mitochondria are organelles located inside eukaryotic cells and are essential for several key cellular processes such as energy (ATP) production, cell signaling, differentiation, and apoptosis. All organisms are believed to have low levels of variation in mitochondrial DNA (mtDNA), and alterations in mtDNA are connected to a range of human health conditions, including epilepsy, heart failure, Parkinsons disease, diabetes, and multiple sclerosis. Therefore, understanding how changes in mtDNA accumulate over time and are correlated to changes in mitochondrial function and cell properties can have a profound impact on our understanding of cell physiology and the origins of some diseases. Motivated by this, we develop and study a mathematical model to determine which cellular parameters have the largest impact on mtDNA population dynamics. The model consists of coupled ODEs to describe subpopulations of healthy and dysfunctional mitochondria subject to mitochondrial fission, fusion, autophagy, and mutation. We study the time evolution and stability of each sub-population under specific selection biases and pressures by tuning specific terms in our model. Our results may provide insights into how sub-populations of mitochondria survive and evolve under different selection pressures. This work was supported by a Grant from the Moore Foundation.

Genomic variation in Plasmodium vivax malaria reveals regions under selective pressure

PubMed Central

Diez Benavente, Ernest; Ward, Zoe; Chan, Wilson; Mohareb, Fady R.; Sutherland, Colin J.; Roper, Cally; Campino, Susana

2017-01-01

Background Although Plasmodium vivax contributes to almost half of all malaria cases outside Africa, it has been relatively neglected compared to the more deadly P. falciparum. It is known that P. vivax populations possess high genetic diversity, differing geographically potentially due to different vector species, host genetics and environmental factors. Results We analysed the high-quality genomic data for 46 P. vivax isolates spanning 10 countries across 4 continents. Using population genetic methods we identified hotspots of selection pressure, including the previously reported MRP1 and DHPS genes, both putative drug resistance loci. Extra copies and deletions in the promoter region of another drug resistance candidate, MDR1 gene, and duplications in the Duffy binding protein gene (PvDBP) potentially involved in erythrocyte invasion, were also identified. For surveillance applications, continental-informative markers were found in putative drug resistance loci, and we show that organellar polymorphisms could classify P. vivax populations across continents and differentiate between Plasmodia spp. Conclusions This study has shown that genomic diversity that lies within and between P. vivax populations can be used to elucidate potential drug resistance and invasion mechanisms, as well as facilitate the molecular barcoding of the parasite for surveillance applications. PMID:28493919

Genomic variation in Plasmodium vivax malaria reveals regions under selective pressure.

PubMed

Diez Benavente, Ernest; Ward, Zoe; Chan, Wilson; Mohareb, Fady R; Sutherland, Colin J; Roper, Cally; Campino, Susana; Clark, Taane G

2017-01-01

Although Plasmodium vivax contributes to almost half of all malaria cases outside Africa, it has been relatively neglected compared to the more deadly P. falciparum. It is known that P. vivax populations possess high genetic diversity, differing geographically potentially due to different vector species, host genetics and environmental factors. We analysed the high-quality genomic data for 46 P. vivax isolates spanning 10 countries across 4 continents. Using population genetic methods we identified hotspots of selection pressure, including the previously reported MRP1 and DHPS genes, both putative drug resistance loci. Extra copies and deletions in the promoter region of another drug resistance candidate, MDR1 gene, and duplications in the Duffy binding protein gene (PvDBP) potentially involved in erythrocyte invasion, were also identified. For surveillance applications, continental-informative markers were found in putative drug resistance loci, and we show that organellar polymorphisms could classify P. vivax populations across continents and differentiate between Plasmodia spp. This study has shown that genomic diversity that lies within and between P. vivax populations can be used to elucidate potential drug resistance and invasion mechanisms, as well as facilitate the molecular barcoding of the parasite for surveillance applications.

The distribution of runs of homozygosity and selection signatures in six commercial meat sheep breeds

PubMed Central

Purfield, Deirdre C.; McParland, Sinead; Wall, Eamon; Berry, Donagh P.

2017-01-01

Domestication and the subsequent selection of animals for either economic or morphological features can leave a variety of imprints on the genome of a population. Genomic regions subjected to high selective pressures often show reduced genetic diversity and frequent runs of homozygosity (ROH). Therefore, the objective of the present study was to use 42,182 autosomal SNPs to identify genomic regions in 3,191 sheep from six commercial breeds subjected to selection pressure and to quantify the genetic diversity within each breed using ROH. In addition, the historical effective population size of each breed was also estimated and, in conjunction with ROH, was used to elucidate the demographic history of the six breeds. ROH were common in the autosomes of animals in the present study, but the observed breed differences in patterns of ROH length and burden suggested differences in breed effective population size and recent management. ROH provided a sufficient predictor of the pedigree inbreeding coefficient, with an estimated correlation between both measures of 0.62. Genomic regions under putative selection were identified using two complementary algorithms; the fixation index and hapFLK. The identified regions under putative selection included candidate genes associated with skin pigmentation, body size and muscle formation; such characteristics are often sought after in modern-day breeding programs. These regions of selection frequently overlapped with high ROH regions both within and across breeds. Multiple yet uncharacterised genes also resided within putative regions of selection. This further substantiates the need for a more comprehensive annotation of the sheep genome as these uncharacterised genes may contribute to traits of interest in the animal sciences. Despite this, the regions identified as under putative selection in the current study provide an insight into the mechanisms leading to breed differentiation and genetic variation in meat production. PMID:28463982

Detecting selection signatures between Duroc and Duroc synthetic pig populations using high-density SNP chip.

PubMed

Edea, Z; Hong, J-K; Jung, J-H; Kim, D-W; Kim, Y-M; Kim, E-S; Shin, S S; Jung, Y C; Kim, K-S

2017-08-01

The development of high throughput genotyping techniques has facilitated the identification of selection signatures of pigs. The detection of genomic selection signals in a population subjected to differential selection pressures may provide insights into the genes associated with economically and biologically important traits. To identify genomic regions under selection, we genotyped 488 Duroc (D) pigs and 155 D × Korean native pigs (DKNPs) using the Porcine SNP70K BeadChip. By applying the F ST and extended haplotype homozygosity (EHH-Rsb) methods, we detected genes under directional selection associated with growth/stature (DOCK7, PLCB4, HS2ST1, FBP2 and TG), carcass and meat quality (TG, COL14A1, FBXO5, NR3C1, SNX7, ARHGAP26 and DPYD), number of teats (LOC100153159 and LRRC1), pigmentation (MME) and ear morphology (SOX5), which are all mostly near or at fixation. These results could be a basis for investigating the underlying mutations associated with observed phenotypic variation. Validation using genome-wide association analysis would also facilitate the inclusion of some of these markers in genetic evaluation programs. © 2017 Stichting International Foundation for Animal Genetics.

Genome-wide analysis of WRKY gene family in Cucumis sativus

PubMed Central

2011-01-01

Background WRKY proteins are a large family of transcriptional regulators in higher plant. They are involved in many biological processes, such as plant development, metabolism, and responses to biotic and abiotic stresses. Prior to the present study, only one full-length cucumber WRKY protein had been reported. The recent publication of the draft genome sequence of cucumber allowed us to conduct a genome-wide search for cucumber WRKY proteins, and to compare these positively identified proteins with their homologs in model plants, such as Arabidopsis. Results We identified a total of 55 WRKY genes in the cucumber genome. According to structural features of their encoded proteins, the cucumber WRKY (CsWRKY) genes were classified into three groups (group 1-3). Analysis of expression profiles of CsWRKY genes indicated that 48 WRKY genes display differential expression either in their transcript abundance or in their expression patterns under normal growth conditions, and 23 WRKY genes were differentially expressed in response to at least one abiotic stresses (cold, drought or salinity). The expression profile of stress-inducible CsWRKY genes were correlated with those of their putative Arabidopsis WRKY (AtWRKY) orthologs, except for the group 3 WRKY genes. Interestingly, duplicated group 3 AtWRKY genes appear to have been under positive selection pressure during evolution. In contrast, there was no evidence of recent gene duplication or positive selection pressure among CsWRKY group 3 genes, which may have led to the expressional divergence of group 3 orthologs. Conclusions Fifty-five WRKY genes were identified in cucumber and the structure of their encoded proteins, their expression, and their evolution were examined. Considering that there has been extensive expansion of group 3 WRKY genes in angiosperms, the occurrence of different evolutionary events could explain the functional divergence of these genes. PMID:21955985

Genome-wide analysis of WRKY gene family in Cucumis sativus.

PubMed

Ling, Jian; Jiang, Weijie; Zhang, Ying; Yu, Hongjun; Mao, Zhenchuan; Gu, Xingfang; Huang, Sanwen; Xie, Bingyan

2011-09-28

WRKY proteins are a large family of transcriptional regulators in higher plant. They are involved in many biological processes, such as plant development, metabolism, and responses to biotic and abiotic stresses. Prior to the present study, only one full-length cucumber WRKY protein had been reported. The recent publication of the draft genome sequence of cucumber allowed us to conduct a genome-wide search for cucumber WRKY proteins, and to compare these positively identified proteins with their homologs in model plants, such as Arabidopsis. We identified a total of 55 WRKY genes in the cucumber genome. According to structural features of their encoded proteins, the cucumber WRKY (CsWRKY) genes were classified into three groups (group 1-3). Analysis of expression profiles of CsWRKY genes indicated that 48 WRKY genes display differential expression either in their transcript abundance or in their expression patterns under normal growth conditions, and 23 WRKY genes were differentially expressed in response to at least one abiotic stresses (cold, drought or salinity). The expression profile of stress-inducible CsWRKY genes were correlated with those of their putative Arabidopsis WRKY (AtWRKY) orthologs, except for the group 3 WRKY genes. Interestingly, duplicated group 3 AtWRKY genes appear to have been under positive selection pressure during evolution. In contrast, there was no evidence of recent gene duplication or positive selection pressure among CsWRKY group 3 genes, which may have led to the expressional divergence of group 3 orthologs. Fifty-five WRKY genes were identified in cucumber and the structure of their encoded proteins, their expression, and their evolution were examined. Considering that there has been extensive expansion of group 3 WRKY genes in angiosperms, the occurrence of different evolutionary events could explain the functional divergence of these genes.

High temperature pressurized high frequency testing rig and test method

DOEpatents

De La Cruz, Jose; Lacey, Paul

2003-04-15

An apparatus is described which permits the lubricity of fuel compositions at or near temperatures and pressures experienced by compression ignition fuel injector components during operation in a running engine. The apparatus consists of means to apply a measured force between two surfaces and oscillate them at high frequency while wetted with a sample of the fuel composition heated to an operator selected temperature. Provision is made to permit operation at or near the flash point of the fuel compositions. Additionally a method of using the subject apparatus to simulate ASTM Testing Method D6079 is disclosed, said method involving using the disclosed apparatus to contact the faces of prepared workpieces under a measured load, sealing the workface contact point into the disclosed apparatus while immersing said contact point between said workfaces in a lubricating media to be tested, pressurizing and heating the chamber and thereby the fluid and workfaces therewithin, using the disclosed apparatus to impart a differential linear motion between the workpieces at their contact point until a measurable scar is imparted to at least one workpiece workface, and then evaluating the workface scar.

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.

MAINTENANCE OF ECOLOGICALLY SIGNIFICANT GENETIC VARIATION IN THE TIGER SWALLOWTAIL BUTTERFLY THROUGH DIFFERENTIAL SELECTION AND GENE FLOW.

PubMed

Bossart, J L; Scriber, J M

1995-12-01

Differential selection in a heterogeneous environment is thought to promote the maintenance of ecologically significant genetic variation. Variation is maintained when selection is counterbalanced by the homogenizing effects of gene flow and random mating. In this study, we examine the relative importance of differential selection and gene flow in maintaining genetic variation in Papilio glaucus. Differential selection on traits contributing to successful use of host plants (oviposition preference and larval performance) was assessed by comparing the responses of southern Ohio, north central Georgia, and southern Florida populations of P. glaucus to three hosts: Liriodendron tulipifera, Magnolia virginiana, and Prunus serotina. Gene flow among populations was estimated using allozyme frequencies from nine polymorphic loci. Significant genetic differentiation was observed among populations for both oviposition preference and larval performance. This differentiation was interpreted to be the result of selection acting on Florida P. glaucus for enhanced use of Magnolia, the prevalent host in Florida. In contrast, no evidence of population differentiation was revealed by allozyme frequencies. F ST -values were very small and Nm, an estimate of the relative strengths of gene flow and genetic drift, was large, indicating that genetic exchange among P. glaucus populations is relatively unrestricted. The contrasting patterns of spatial differentiation for host-use traits and lack of differentiation for electrophoretically detectable variation implies that differential selection among populations will be counterbalanced by gene flow, thereby maintaining genetic variation for host-use traits. © 1995 The Society for the Study of Evolution.

Development of a Nutritional Delivery System to Feed Crew in a Pressurized Suit

NASA Technical Reports Server (NTRS)

Glass, J. W.; Leonig, M. L.; Douglas, G. L.

2014-01-01

The contingency scenario for an emergency cabin depressurization event may require crewmembers to subsist in a pressurized suit for up to 144 hours. This scenario requires the capability for safe nutrition delivery through a helmet feed port against a 4 psi pressure differential to enable crewmembers to maintain strength and cognition to perform critical tasks. Two nutritional delivery prototypes were developed and analyzed for compatibility with the helmet feed port interface and for operational effectiveness against the pressure differential. The bag-in-bag (BiB) prototype, designed to equalize the suit pressure with the beverage pouch and enable a crewmember to drink normally, delivered water successfully to three different subjects in suits pressurized to 4 psi. The Boa restrainer pouch, designed to provide mechanical leverage to overcome the pressure differential, did not operate sufficiently. Guidelines were developed and compiled for contingency beverages that provide macro-nutritional requirements, a minimum one-year shelf life, and compatibility with the delivery hardware. Evaluation results and food product parameters have the potential to be used to improve future prototype designs and develop complete nutritional beverages for contingency events. These feeding capabilities would have additional use on extended surface mission EVAs, where the current in-suit drinking device may be insufficient.

Tank depletion flow controller

DOEpatents

Georgeson, Melvin A.

1976-10-26

A flow control system includes two bubbler tubes installed at different levels within a tank containing such as radioactive liquid. As the tank is depleted, a differential pressure transmitter monitors pressure differences imparted by the two bubbler tubes at a remote, shielded location during uniform time intervals. At the end of each uniform interval, balance pots containing a dense liquid are valved together to equalize the pressures. The resulting sawtooth-shaped signal generated by the differential pressure transmitter is compared with a second sawtooth signal representing the desired flow rate during each time interval. Variations in the two signals are employed by a control instrument to regulate flow rate.

Suited Contingency Ops Food - 2

NASA Technical Reports Server (NTRS)

Glass, J. W.; Leong, M. L.; Douglas, G. L.

2014-01-01

The contingency scenario for an emergency cabin depressurization event may require crewmembers to subsist in a pressurized suit for up to 144 hours. This scenario requires the capability for safe nutrition delivery through a helmet feed port against a 4 psi pressure differential to enable crewmembers to maintain strength and cognition to perform critical tasks. Two nutritional delivery prototypes were developed and analyzed for compatibility with the helmet feed port interface and for operational effectiveness against the pressure differential. The bag-in-bag (BiB) prototype, designed to equalize the suit pressure with the beverage pouch and enable a crewmember to drink normally, delivered water successfully to three different subjects in suits pressurized to 4 psi. The Boa restrainer pouch, designed to provide mechanical leverage to overcome the pressure differential, did not operate sufficiently. Guidelines were developed and compiled for contingency beverages that provide macro-nutritional requirements, a minimum one-year shelf life, and compatibility with the delivery hardware. Evaluation results and food product parameters have the potential to be used to improve future prototype designs and develop complete nutritional beverages for contingency events. These feeding capabilities would have additional use on extended surface mission EVAs, where the current in-suit drinking device may be insufficient.

Obesity, free testosterone, and cardiovascular risk factors in adolescents with polycystic ovary syndrome and regularly cycling adolescents.

PubMed

Glueck, Charles J; Morrison, John A; Friedman, Lisa Aronson; Goldenberg, Naila; Stroop, Davis M; Wang, Ping

2006-04-01

Adolescent girls with polycystic ovary syndrome (PCOS) have increased levels of factors constituting the metabolic syndrome: centripetal obesity, hypertension, hypertriglyceridemia, low high-density lipoprotein cholesterol (HDL-C), and hyperinsulinemia. Given the strong association reported between early, persistent obesity and development of metabolic syndrome 10 years later in girls, we speculated that if adolescent girls without PCOS had obesity measures similar to girls with PCOS, they would exhibit similar metabolic syndrome-cardiovascular disease risk factors. Within this context, we compared 37 adolescent girls with PCOS and 2 samples of normal, regularly cycling adolescent girls (controls) of similar ages, selected from the Cincinnati Clinic of the National Heart, Lung, and Blood Institute Growth and Health Study. The first sample included 157 controls selected using a stratified random sample based on age. As expected, girls with PCOS had higher body mass index (BMI), waist circumference, insulin, systolic blood pressure (SBP) and diastolic blood pressure, triglycerides (TGs), lower HDL-C, and higher low-density lipoprotein cholesterol (LDL-C) and free testosterone (FT) than controls. A second sample consisted of girls matched one to one with girls with PCOS for BMI and age. Comparisons of group differences were not significant for insulin, lipids, or blood pressure; girls with PCOS had a trend toward higher values for waist circumference (median, 92.7 vs 87.5 cm; P = .07) and much higher median FT (4.25 vs 1.42 ng/mL, P = .0001). After matching for BMI and age, by conditional regression analysis, we showed that the groups were not differentiated (P > .15) by insulin, HDL-C, LDL-C, TG, SBP, or diastolic blood pressure, but were differentiated by higher FT (P = .0024) and waist circumference (P = .0024) in PCOS than in controls. Prospective longitudinal analyses of NHGS controls showed that changes in BMI from ages 9 to 10 years to ages 15 to 16 years were positively associated with changes in waist circumference (P < .0001), LDL-C (P = .01), TG (P = .008), and SBP (P = .002). These findings suggest that if adolescent girls achieve adiposity equal to girls with PCOS, they then acquire major components of the metabolic syndrome, and excluding high FT and waist circumference, comparable increased cardiovascular disease risk.

Interaction of central venous pressure, intramuscular pressure, and carotid baroreflex function

NASA Technical Reports Server (NTRS)

Shi, X.; Foresman, B. H.; Raven, P. B.; Blomqvist, C. G. (Principal Investigator)

1997-01-01

Seven healthy volunteer men participated in an experiment involving lower body positive pressure (LBPP) of 30 Torr and acute volume expansions of 5-6% (VE-I) and 9-10% (VE-II) of their total blood volume (TBV) to differentiate the effect of increased intramuscular pressure and central venous pressure (CVP) on the maximal gain (Gmax) of the carotid baroreflex. During each experimental condition, the heart rate (HR), mean arterial pressure (MAP; intraradial artery or Finapres), and CVP (at the 3rd-4th intercostal space) were monitored continuously. Gmax was derived from the logistic modeling of the HR and MAP responses to ramped changes in carotid sinus transmural pressure using a protocol of pulsatile changes in neck chamber pressure from +40 to -65 Torr. The increase in CVP during +30-Torr LBPP was 1.5 mmHg (P < 0.05) and was similar to that observed during VE-I (1.7 mmHg, P > 0.05). The Gmax of the carotid baroreflex of HR and MAP was significantly decreased during LBPP by -0.145 +/- 0.039 beats x min(-1) x mmHg(-1) (38%) and -0.071 +/- 0.013 mmHg/mmHg (25%), respectively; however, VE-I did not affect Gmax. During VE-II, CVP was significantly greater than that elicited by LBPP, and the Gmax of the carotid baroreflex of the HR and MAP responses was significantly reduced. We conclude that carotid baroreflex responsiveness was selectively inhibited by increasing intramuscular pressure, possibly resulting in an activation of the intramuscular mechanoreceptors during LBPP. Furthermore, it would appear that the inhibition of the carotid baroreflex, via cardiopulmonary baroreceptor loading (increased CVP), occurred when a threshold pressure (CVP) was achieved.

Human genomic regions with exceptionally high levels of population differentiation identified from 911 whole-genome sequences.

PubMed

Colonna, Vincenza; Ayub, Qasim; Chen, Yuan; Pagani, Luca; Luisi, Pierre; Pybus, Marc; Garrison, Erik; Xue, Yali; Tyler-Smith, Chris; Abecasis, Goncalo R; Auton, Adam; Brooks, Lisa D; DePristo, Mark A; Durbin, Richard M; Handsaker, Robert E; Kang, Hyun Min; Marth, Gabor T; McVean, Gil A

2014-06-30

Population differentiation has proved to be effective for identifying loci under geographically localized positive selection, and has the potential to identify loci subject to balancing selection. We have previously investigated the pattern of genetic differentiation among human populations at 36.8 million genomic variants to identify sites in the genome showing high frequency differences. Here, we extend this dataset to include additional variants, survey sites with low levels of differentiation, and evaluate the extent to which highly differentiated sites are likely to result from selective or other processes. We demonstrate that while sites with low differentiation represent sampling effects rather than balancing selection, sites showing extremely high population differentiation are enriched for positive selection events and that one half may be the result of classic selective sweeps. Among these, we rediscover known examples, where we actually identify the established functional SNP, and discover novel examples including the genes ABCA12, CALD1 and ZNF804, which we speculate may be linked to adaptations in skin, calcium metabolism and defense, respectively. We identify known and many novel candidate regions for geographically restricted positive selection, and suggest several directions for further research.

Insecticide-driven patterns of genetic variation in the dengue vector Aedes aegypti in Martinique Island.

PubMed

Marcombe, Sébastien; Paris, Margot; Paupy, Christophe; Bringuier, Charline; Yebakima, André; Chandre, Fabrice; David, Jean-Philippe; Corbel, Vincent; Despres, Laurence

2013-01-01

Effective vector control is currently challenged worldwide by the evolution of resistance to all classes of chemical insecticides in mosquitoes. In Martinique, populations of the dengue vector Aedes aegypti have been intensively treated with temephos and deltamethrin insecticides over the last fifty years, resulting in heterogeneous levels of resistance across the island. Resistance spreading depends on standing genetic variation, selection intensity and gene flow among populations. To determine gene flow intensity, we first investigated neutral patterns of genetic variability in sixteen populations representative of the many environments found in Martinique and experiencing various levels of insecticide pressure, using 6 microsatellites. Allelic richness was lower in populations resistant to deltamethrin, and consanguinity was higher in populations resistant to temephos, consistent with a negative effect of insecticide pressure on neutral genetic diversity. The global genetic differentiation was low, suggesting high gene flow among populations, but significant structure was found, with a pattern of isolation-by-distance at the global scale. Then, we investigated adaptive patterns of divergence in six out of the 16 populations using 319 single nucleotide polymorphisms (SNPs). Five SNP outliers displaying levels of genetic differentiation out of neutral expectations were detected, including the kdr-V1016I mutation in the voltage-gated sodium channel gene. Association tests revealed a total of seven SNPs associated with deltamethrin resistance. Six other SNPs were associated with temephos resistance, including two non-synonymous substitutions in an alkaline phosphatase and in a sulfotransferase respectively. Altogether, both neutral and adaptive patterns of genetic variation in mosquito populations appear to be largely driven by insecticide pressure in Martinique.

Atlantic salmon populations reveal adaptive divergence of immune related genes - a duplicated genome under selection.

PubMed

Kjærner-Semb, Erik; Ayllon, Fernando; Furmanek, Tomasz; Wennevik, Vidar; Dahle, Geir; Niemelä, Eero; Ozerov, Mikhail; Vähä, Juha-Pekka; Glover, Kevin A; Rubin, Carl J; Wargelius, Anna; Edvardsen, Rolf B

2016-08-11

Populations of Atlantic salmon display highly significant genetic differences with unresolved molecular basis. These differences may result from separate postglacial colonization patterns, diversifying natural selection and adaptation, or a combination. Adaptation could be influenced or even facilitated by the recent whole genome duplication in the salmonid lineage which resulted in a partly tetraploid species with duplicated genes and regions. In order to elucidate the genes and genomic regions underlying the genetic differences, we conducted a genome wide association study using whole genome resequencing data from eight populations from Northern and Southern Norway. From a total of ~4.5 million sequencing-derived SNPs, more than 10 % showed significant differentiation between populations from these two regions and ten selective sweeps on chromosomes 5, 10, 11, 13-15, 21, 24 and 25 were identified. These comprised 59 genes, of which 15 had one or more differentiated missense mutation. Our analysis showed that most sweeps have paralogous regions in the partially tetraploid genome, each lacking the high number of significant SNPs found in the sweeps. The most significant sweep was found on Chr 25 and carried several missense mutations in the antiviral mx genes, suggesting that these populations have experienced differing viral pressures. Interestingly the second most significant sweep, found on Chr 5, contains two genes involved in the NF-KB pathway (nkap and nkrf), which is also a known pathogen target that controls a large number of processes in animals. Our results show that natural selection acting on immune related genes has contributed to genetic divergence between salmon populations in Norway. The differences between populations may have been facilitated by the plasticity of the salmon genome. The observed signatures of selection in duplicated genomic regions suggest that the recently duplicated genome has provided raw material for evolutionary adaptation.

Genetic and phenotypic differentiation of an Andean intermediate altitude population

PubMed Central

Eichstaedt, Christina A; Antão, Tiago; Cardona, Alexia; Pagani, Luca; Kivisild, Toomas; Mormina, Maru

2015-01-01

Highland populations living permanently under hypobaric hypoxia have been subject of extensive research because of the relevance of their physiological adaptations for the understanding of human health and disease. In this context, what is considered high altitude is a matter of interpretation and while the adaptive processes at high altitude (above 3000 m) are well documented, the effects of moderate altitude (below 3000 m) on the phenotype are less well established. In this study, we compare physiological and anthropometric characteristics as well as genetic variations in two Andean populations: the Calchaquíes (2300 m) and neighboring Collas (3500 m). We compare their phenotype and genotype to the sea-level Wichí population. We measured physiological (heart rate, oxygen saturation, respiration rate, and lung function) as well as anthropometric traits (height, sitting height, weight, forearm, and tibia length). We conducted genome-wide genotyping on a subset of the sample (n = 74) and performed various scans for positive selection. At the phenotypic level (n = 179), increased lung capacity stood out in both Andean groups, whereas a growth reduction in distal limbs was only observed at high altitude. At the genome level, Calchaquíes revealed strong signals around PRKG1, suggesting that the nitric oxide pathway may be a target of selection. PRKG1 was highlighted by one of four selection tests among the top five genes using the population branch statistic. Selection tests results of Collas were reported previously. Overall, our study shows that some phenotypic and genetic differentiation occurs at intermediate altitude in response to moderate lifelong selection pressures. PMID:25948820

A wet/wet differential pressure sensor for measuring vertical hydraulic gradient.

PubMed

Fritz, Brad G; Mackley, Rob D

2010-01-01

Vertical hydraulic gradient is commonly measured in rivers, lakes, and streams for studies of groundwater-surface water interaction. While a number of methods with subtle differences have been applied, these methods can generally be separated into two categories; measuring surface water elevation and pressure in the subsurface separately or making direct measurements of the head difference with a manometer. Making separate head measurements allows for the use of electronic pressure sensors, providing large datasets that are particularly useful when the vertical hydraulic gradient fluctuates over time. On the other hand, using a manometer-based method provides an easier and more rapid measurement with a simpler computation to calculate the vertical hydraulic gradient. In this study, we evaluated a wet/wet differential pressure sensor for use in measuring vertical hydraulic gradient. This approach combines the advantage of high-temporal frequency measurements obtained with instrumented piezometers with the simplicity and reduced potential for human-induced error obtained with a manometer board method. Our results showed that the wet/wet differential pressure sensor provided results comparable to more traditional methods, making it an acceptable method for future use.

Caste load and the evolution of reproductive skew.

PubMed

Holman, Luke

2014-01-01

Reproductive skew theory seeks to explain how reproduction is divided among group members in animal societies. Existing theory is framed almost entirely in terms of selection, though nonadaptive processes must also play some role in the evolution of reproductive skew. Here I propose that a genetic correlation between helper fecundity and breeder fecundity may frequently constrain the evolution of reproductive skew. This constraint is part of a wider phenomenon that I term "caste load," which is defined as the decline in mean fitness caused by caste-specific selection pressures, that is, differential selection on breeding and nonbreeding individuals. I elaborate the caste load hypothesis using quantitative and population genetic arguments and individual-based simulations. Although selection can sometimes erode genetic correlations and resolve caste load, this may be constrained when mutations have similar pleiotropic effects on breeder and helper traits. I document evidence for caste load, identify putative genomic adaptations to it, and suggest future research directions. The models highlight the value of considering adaptation within the boundaries imposed by genetic architecture and incidentally reaffirm that monogamy promotes the evolutionary transition to eusociality.

Complexity in models of cultural niche construction with selection and homophily.

PubMed

Creanza, Nicole; Feldman, Marcus W

2014-07-22

Niche construction is the process by which organisms can alter the ecological environment for themselves, their descendants, and other species. As a result of niche construction, differences in selection pressures may be inherited across generations. Homophily, the tendency of like phenotypes to mate or preferentially associate, influences the evolutionary dynamics of these systems. Here we develop a model that includes selection and homophily as independent culturally transmitted traits that influence the fitness and mate choice determined by another focal cultural trait. We study the joint dynamics of a focal set of beliefs, a behavior that can differentially influence the fitness of those with certain beliefs, and a preference for partnering based on similar beliefs. Cultural transmission, selection, and homophily interact to produce complex evolutionary dynamics, including oscillations, stable polymorphisms of all cultural phenotypes, and simultaneous stability of oscillation and fixation, which have not previously been observed in models of cultural evolution or gene-culture interactions. We discuss applications of this model to the interaction of beliefs and behaviors regarding education, contraception, and animal domestication.

Ecotypic differentiation and phenotypic plasticity combine to enhance the invasiveness of the most widespread daisy in Chile, Leontodon saxatilis.

PubMed

Martín-Forés, Irene; Avilés, Marta; Acosta-Gallo, Belén; Breed, Martin F; Del Pozo, Alejandro; de Miguel, José M; Sánchez-Jardón, Laura; Castro, Isabel; Ovalle, Carlos; Casado, Miguel A

2017-05-08

Dispersal and reproductive traits of successful plant invaders are expected to undergo strong selection during biological invasions. Numerous Asteraceae are invasive and display dimorphic fruits within a single flower head, resulting in differential dispersal pathways - wind-dispersed fruits vs. non-dispersing fruits. We explored ecotypic differentiation and phenotypic plasticity of seed output and fruit dimorphisms in exotic Chilean and native Spanish populations of Leontodon saxatilis subsp. rothii. We collected flower heads from populations in Spain and Chile along a rainfall gradient. Seeds from all populations were planted in reciprocal transplant trials in Spain and Chile to explore their performance in the native and invasive range. We scored plant biomass, reproductive investment and fruit dimorphism. We observed strong plasticity, where plants grown in the invasive range had much greater biomass, flower head size and seed output, with a higher proportion of wind-dispersed fruits, than those grown in the native range. We also observed a significant ecotype effect, where the exotic populations displayed higher proportions of wind-dispersed fruits than native populations. Together, these patterns reflect a combination of phenotypic plasticity and ecotypic differentiation, indicating that Leontodon saxatilis has probably increased propagule pressure and dispersal distances in its invasive range to enhance its invasiveness.

Viscosity-adjusted estimation of pressure head and pump flow with quasi-pulsatile modulation of rotary blood pump for a total artificial heart.

PubMed

Yurimoto, Terumi; Hara, Shintaro; Isoyama, Takashi; Saito, Itsuro; Ono, Toshiya; Abe, Yusuke

2016-09-01

Estimation of pressure and flow has been an important subject for developing implantable artificial hearts. To realize real-time viscosity-adjusted estimation of pressure head and pump flow for a total artificial heart, we propose the table estimation method with quasi-pulsatile modulation of rotary blood pump in which systolic high flow and diastolic low flow phased are generated. The table estimation method utilizes three kinds of tables: viscosity, pressure and flow tables. Viscosity is estimated from the characteristic that differential value in motor speed between systolic and diastolic phases varies depending on viscosity. Potential of this estimation method was investigated using mock circulation system. Glycerin solution diluted with salty water was used to adjust viscosity of fluid. In verification of this method using continuous flow data, fairly good estimation could be possible when differential pulse width modulation (PWM) value of the motor between systolic and diastolic phases was high. In estimation under quasi-pulsatile condition, inertia correction was provided and fairly good estimation was possible when the differential PWM value was high, which was not different from the verification results using continuous flow data. In the experiment of real-time estimation applying moving average method to the estimated viscosity, fair estimation could be possible when the differential PWM value was high, showing that real-time viscosity-adjusted estimation of pressure head and pump flow would be possible with this novel estimation method when the differential PWM value would be set high.

Mechanical characterization and durability of sintered porous transport layers for polymer electrolyte membrane electrolysis

NASA Astrophysics Data System (ADS)

Borgardt, Elena; Panchenko, Olha; Hackemüller, Franz Josef; Giffin, Jürgen; Bram, Martin; Müller, Martin; Lehnert, Werner; Stolten, Detlef

2018-01-01

Differential pressure electrolysis offers the potential for more efficient hydrogen compression. Due to the differential pressures acting within the electrolytic cell, the porous transport layer (PTL) is subjected to high stress. For safety reasons, the PTL's mechanical stability must be ensured. However, the requirements for high porosity and low thickness stand in contrast to that for mechanical stability. Porous transport layers for polymer electrolyte membrane (PEM) electrolysis are typically prepared by means of the thermal sintering of titanium powder. Thus far, the factors that influence the mechanical strength of the sintered bodies and how all requirements can be simultaneously fulfilled have not been investigated. Here, the static and dynamic mechanical properties of thin sintered titanium sheets are investigated ex-situ via tensile tests and periodic loading in a test cell, respectively. In order for a sintered PTL with a thickness of 500 μm and porosities above 25% to be able to withstand 50 bar differential pressure in the cell, the maximum flow field width should be limited to 3 mm. Thus, a method was developed to test the suitability of PTL materials for use in electrolysis for various differential pressures and flow field widths.

Development of a 5,000 m(3) super-pressure balloon with a diamond-shaped net

NASA Astrophysics Data System (ADS)

Saito, Yoshitaka; Tanaka, Shigeki; Nakashino, Kyoichi; Matsushima, Kiyoho; Goto, Ken; Furuta, Ryosuke; Domoto, Kodai; Akita, Daisuke; Hashimoto, Hiroyuki

A light super-pressure balloon of which weight will be comparable to the weight of the zero-pressure balloon has been developed using a method to cover a balloon with a diamond-shaped net of high-tensile fibers. The goal is to fly a payload of 900 kg to the altitude of 37 km with a 300,000 m(3) balloon. A flight test of a 3,000 m(3) balloon in the tandem balloon configuration with a 15,000 m(3) zero-pressure balloon was performed in 2012. Although a small gas leak occurred in the super-pressure balloon at the differential pressure of 400 to 500 Pa, the differential pressure reached the highest value of 814 Pa and kept positive through the level flight lasting for 25 minutes due to its slow leakage. To avoid a possible stress concentration to films at the polar area, a new design setting the meridian length of the balloon gore film equal to the length of the net was adopted. A 3-m balloon with the design was developed and its capacity to resist pressure at room temperature and at -30 (°) C was checked through the ground inflation tests. In 2013, a balloon of the same model was launched in the tandem balloon configuration with 2 kg rubber balloons. It was confirmed that the balloon could withstand the maximum differential pressure of 6,280 Pa, could withstand the differential pressure of 5,600 Pa for 2 hours, and there was a small gas leak through a hole with an area of 0.4 mm(2) which was also found in the ground leakage test. These results indicated that the improvement was adequate and there was no problem for the super-pressure balloon to fly in the environment of the stratosphere except for the problem of the small gas leak. In 2014, a flight test of a 5,000 m(3) balloon will be performed. In this paper, after reviewing the method to cover a balloon with a diamond-shaped net, the current status of the development will be reported.

Diffusion Dynamics and Creative Destruction in a Simple Classical Model

PubMed Central

2015-01-01

ABSTRACT The article explores the impact of the diffusion of new methods of production on output and employment growth and income distribution within a Classical one‐sector framework. Disequilibrium paths are studied analytically and in terms of simulations. Diffusion by differential growth affects aggregate dynamics through several channels. The analysis reveals the non‐steady nature of economic change and shows that the adaptation pattern depends both on the innovation's factor‐saving bias and on the extent of the bias, which determines the strength of the selection pressure on non‐innovators. The typology of different cases developed shows various aspects of Schumpeter's concept of creative destruction. PMID:27642192

Method and system for measuring multiphase flow using multiple pressure differentials

DOEpatents

Fincke, James R.

2001-01-01

An improved method and system for measuring a multiphase flow in a pressure flow meter. An extended throat venturi is used and pressure of the multiphase flow is measured at three or more positions in the venturi, which define two or more pressure differentials in the flow conduit. The differential pressures are then used to calculate the mass flow of the gas phase, the total mass flow, and the liquid phase. The method for determining the mass flow of the high void fraction fluid flow and the gas flow includes certain steps. The first step is calculating a gas density for the gas flow. The next two steps are finding a normalized gas mass flow rate through the venturi and computing a gas mass flow rate. The following step is estimating the gas velocity in the venturi tube throat. The next step is calculating the pressure drop experienced by the gas-phase due to work performed by the gas phase in accelerating the liquid phase between the upstream pressure measuring point and the pressure measuring point in the venturi throat. Another step is estimating the liquid velocity in the venturi throat using the calculated pressure drop experienced by the gas-phase due to work performed by the gas phase. Then the friction is computed between the liquid phase and a wall in the venturi tube. Finally, the total mass flow rate based on measured pressure in the venturi throat is calculated, and the mass flow rate of the liquid phase is calculated from the difference of the total mass flow rate and the gas mass flow rate.

[Differentiation between moisture lesions and pressure ulcers using photographs in a critical area].

PubMed

Valls-Matarín, Josefa; Del Cotillo-Fuente, Mercedes; Pujol-Vila, María; Ribal-Prior, Rosa; Sandalinas-Mulero, Inmaculada

2016-01-01

To identify difficulties for nurses in differentiating between moisture lesions and pressure ulcers, proper classification of pressure ulcers to assess the adequate classification of the Grupo Nacional para el Estudio y Asesoramiento de Úlceras por Presión y Heridas Crónicas (GNEAUPP) and the degree of agreement in the correct assessment by type and category of injury. Cross-sectional study in a critical area during 2014. All nurses who agreed to participate were included. They performed a questionnaire with 14 photographs validated by experts of moisture lesions or pressure ulcers in the sacral area and buttocks, with 6 possible answers: Pressure ulcer category I, II, III, IV, moisture lesions and unknown. Demographics and knowledge of the classification system of the pressure ulcers were collected according to GNEAUPP. It involved 98% of the population (n=56); 98.2% knew the classification system of the GNEAUPP; 35.2% of moisture lesions were considered as pressure ulcers, most of them as a category II (18.9%). The 14.8% of the pressure ulcers photographs were identified as moisture lesions and 16.1% were classified in another category. The agreement between nurses earned a global Kappa index of .38 (95% CI: .29-.57). There are difficulties differentiating between pressure ulcers and moisture lesions, especially within initial categories. Nurses have the perception they know the pressure ulcers classification, but they do not classify them correctly. The degree of concordance in the diagnosis of skin lesions was low. Copyright © 2016 Elsevier España, S.L.U. All rights reserved.

Check valve installation in pilot operated relief valve prevents reverse pressurization

NASA Technical Reports Server (NTRS)

Oswalt, L.

1966-01-01

Two check valves prevent reverse flow through pilot-operated relief valves of differential area piston design. Title valves control pressure flow to ensure that the piston dome pressure is always at least as great as the main relief valve discharge pressure.

Evoked Pressure Pain Sensitivity Is Associated with Differential Analgesic Response to Verum and Sham Acupuncture in Fibromyalgia.

PubMed

Zucker, Noah A; Tsodikov, Alex; Mist, Scott D; Cina, Stephen; Napadow, Vitaly; Harris, Richard E

2017-08-01

Fibromyalgia is a chronic pain condition with few effective treatments. Many fibromyalgia patients seek acupuncture for analgesia; however, its efficacy is limited and not fully understood. This may be due to heterogeneous pathologies among participants in acupuncture clinical trials. We hypothesized that pressure pain tenderness would differentially classify treatment response to verum and sham acupuncture in fibromyalgia patients. Baseline pressure pain sensitivity at the thumbnail at baseline was used in linear mixed models as a modifier of differential treatment response to sham versus verum acupuncture. Similarly, needle-induced sensation was also analyzed to determine its differential effect of treatment on clinical pain. A cohort of 114 fibromyalgia patients received baseline pressure pain testing and were randomized to either verum (N = 59) or sham (N = 55) acupuncture. Participants received treatments from once a week to three times a week, increasing in three-week blocks for a total of 18 treatments. Clinical pain was measured on a 101-point visual analog scale, and needle sensation was measured by questionnaire throughout the trial. Participants who had higher pain pressure thresholds had greater reduction in clinical pain following verum acupuncture while participants who had lower pain pressure thresholds showed better analgesic response to sham acupuncture. Moreover, patients with lower pressure pain thresholds had exacerbated clinical pain following verum acupuncture. Similar relationships were observed for sensitivity to acupuncture needling. These findings suggest that acupuncture efficacy in fibromyalgia may be underestimated and a more personalized treatment for fibromyalgia may also be possible. © 2017 American Academy of Pain Medicine. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com

High-pressure differential thermal analysis/dilatometric apparatus based on an Instron capillary rheometer

NASA Astrophysics Data System (ADS)

Hsiao, B. S.; Shaw, M. T.; Samulski, E. T.

1987-06-01

A high-pressure apparatus in the form of a modified Instron capillary rheometer capable of measuring differential thermal analysis (DTA) data and pressure-volume-temperature (P-V-T) relations was constructed in our laboratory. Temperatures from 20 to 370 °C and pressures from 1 to 6000 bar are achievable with a data-acquisition and control system based on an APPLE II+ microcomputer. Measurements of pressure to an accuracy of 1%, temperature of 0.5%, and volume change of 0.1% have been obtained. Software was developed to operate the experiments at fixed heating or cooling rates as well as at a constant pressure or with isothermal pressure sweeps. Polymer samples were compressed into rods preceding the experiment by a vacuum molder to eliminate voids. Low-density polyethylene (LDPE) was run as an example to demonstrate the performance of this pressure apparatus. The results revealed an excellent match between our experimental data and the published data.

Method of fabricating an article with cavities. [with thin bottom walls

NASA Technical Reports Server (NTRS)

Dale, W. J.; Jurscaga, G. M. (Inventor)

1974-01-01

An article having a cavity with a thin bottom wall is provided by assembling a thin sheet, for example, a metal sheet, adjacent to the surface of a member having one or more apertures. A bonding adhesive is interposed between the thin sheet and the subadjacent member, and the thin sheet is subjected to a high fluid pressure. In order to prevent the differential pressure from being exerted against the thin sheet, the aperture is filled with a plug of solid material having a linear coefficient of thermal expansion higher than that of the member. When the assembly is subjected to pressure, the material is heated to a temperature such that its expansion exerts a pressure against the thin sheet thus reducing the differential pressure.

Mitochondrial complex I and NAD(P)H oxidase are major sources of exacerbated oxidative stress in pressure-overloaded ischemic-reperfused hearts.

PubMed

Mozaffari, Mahmood S; Baban, Babak; Liu, Jun Yao; Abebe, Worku; Sullivan, Jennifer C; El-Marakby, Ahmed

2011-03-01

We tested the hypothesis that pressure overload exacerbates oxidative stress associated with augmented mitochondrial permeability transition (MPT) pore opening and cell death in ischemic-reperfused hearts. Pressure overload decreased the level of reduced glutathione but increased nitrotyrosine and 8-hydroxydeoxyguanosine levels in ischemic-reperfused hearts. The activity of catalase, but not superoxide dismutase (SOD), was lower in ischemic-reperfused hearts perfused at higher pressure. Mitochondria from ischemic-reperfused hearts subjected to higher perfusion pressure displayed significantly greater [³H]-2-deoxyglucose-6-P entrapment suggestive of greater MPT pore opening and consistent with greater necrosis and apoptosis. Tempol (SOD mimetic) reduced infarct size in both groups but it remained greater in the higher pressure group. By contrast, uric acid (peroxynitrite scavenger) markedly reduced infarct size at higher pressure, effectively eliminating the differential between the two groups. Inhibition of xanthine oxidase, with allopurinol, reduced infarct size but did not eliminate the differential between the two groups. However, amobarbital (inhibitor of mitochondrial complex I) or apocynin [inhibitor of NAD(P)H oxidase] reduced infarct size at both pressures and also abrogated the differential between the two groups. Consistent with the effect of apocynin, pressure-overloaded hearts displayed significantly higher NAD(P)H oxidase activity. Furthermore, pressure-overloaded hearts displayed increased nitric oxide synthase activity which, along with increased propensity to superoxide generation, may underlie uric acid-induced cardioprotection. In conclusion, increased oxidative and nitrosative stress, coupled with lack of augmented SOD and catalase activities, contributes importantly to the exacerbating impact of pressure overload on MPT pore opening and cell death in ischemic-reperfused hearts.

Making Large Composite Vessels Without Autoclaves

NASA Technical Reports Server (NTRS)

Sigur, W. A.

1989-01-01

Method for making fiber-reinforced composite structure relies on heating and differential thermal expansion to provide temperature and pressure necessary to develop full strength, without having to place structure in large, expensive autoclave. Layers of differentially expanding material squeeze fiber-reinforce composite between them when heated. Method suitable for such cylindrical structures as pressure vessels and tanks. Used for both resin-matrix and metal-matrix composites.

Stability analysis of coupled torsional vibration and pressure in oilwell drillstring system

NASA Astrophysics Data System (ADS)

Toumi, S.; Beji, L.; Mlayeh, R.; Abichou, A.

2018-01-01

To address security issues in oilwell drillstring system, the drilling operation handling which is in generally not autonomous but ensured by an operator may be drill bit destructive or fatal for the machine. To control of stick-slip phenomenon, the drillstring control at the right speed taking only the drillstring vibration is not sufficient as the mud dynamics and the pressure change around the drill pipes cannot be neglected. A coupled torsional vibration and pressure model is presented, and the well-posedness problem is addressed. As a Partial Differential Equation-Ordinary Differential Equation (PDE-ODE) coupled system, and in order to maintain a non destructive downhole pressure, we investigate the control stability with and without the damping term in the wave PDE. In terms of, the torsional variable, the downhole pressure, and the annulus pressure, the coupled system equilibrium is shown to be exponentially stable.

Selection by pollinators on floral traits in generalized Trollius ranunculoides (Ranunculaceae) along altitudinal gradients.

PubMed

Zhao, Zhi-Gang; Wang, Yi-Ke

2015-01-01

Abundance and visitation of pollinator assemblages tend to decrease with altitude, leading to an increase in pollen limitation. Thus increased competition for pollinators may generate stronger selection on attractive traits of flowers at high elevations and cause floral adaptive evolution. Few studies have related geographically variable selection from pollinators and intraspecific floral differentiation. We investigated the variation of Trollius ranunculoides flowers and its pollinators along an altitudinal gradient on the eastern Qinghai-Tibet Plateau, and measured phenotypic selection by pollinators on floral traits across populations. The results showed significant decline of visitation rate of bees along altitudinal gradients, while flies was unchanged. When fitness is estimated by the visitation rate rather than the seed number per plant, phenotypic selection on the sepal length and width shows a significant correlation between the selection strength and the altitude, with stronger selection at higher altitudes. However, significant decreases in the sepal length and width of T. ranunculoides along the altitudinal gradient did not correspond to stronger selection of pollinators. In contrast to the pollinator visitation, mean annual precipitation negatively affected the sepal length and width, and contributed more to geographical variation in measured floral traits than the visitation rate of pollinators. Therefore, the sepal size may have been influenced by conflicting selection pressures from biotic and abiotic selective agents. This study supports the hypothesis that lower pollinator availability at high altitude can intensify selection on flower attractive traits, but abiotic selection is preventing a response to selection from pollinators.

Selection by Pollinators on Floral Traits in Generalized Trollius ranunculoides (Ranunculaceae) along Altitudinal Gradients

PubMed Central

Zhao, Zhi-Gang; Wang, Yi-Ke

2015-01-01

Abundance and visitation of pollinator assemblages tend to decrease with altitude, leading to an increase in pollen limitation. Thus increased competition for pollinators may generate stronger selection on attractive traits of flowers at high elevations and cause floral adaptive evolution. Few studies have related geographically variable selection from pollinators and intraspecific floral differentiation. We investigated the variation of Trollius ranunculoides flowers and its pollinators along an altitudinal gradient on the eastern Qinghai-Tibet Plateau, and measured phenotypic selection by pollinators on floral traits across populations. The results showed significant decline of visitation rate of bees along altitudinal gradients, while flies was unchanged. When fitness is estimated by the visitation rate rather than the seed number per plant, phenotypic selection on the sepal length and width shows a significant correlation between the selection strength and the altitude, with stronger selection at higher altitudes. However, significant decreases in the sepal length and width of T. ranunculoides along the altitudinal gradient did not correspond to stronger selection of pollinators. In contrast to the pollinator visitation, mean annual precipitation negatively affected the sepal length and width, and contributed more to geographical variation in measured floral traits than the visitation rate of pollinators. Therefore, the sepal size may have been influenced by conflicting selection pressures from biotic and abiotic selective agents. This study supports the hypothesis that lower pollinator availability at high altitude can intensify selection on flower attractive traits, but abiotic selection is preventing a response to selection from pollinators. PMID:25692295

Focus control system for stretched-membrane mirror module

DOEpatents

Butler, B.L.; Beninga, K.J.

1991-05-21

A focus control system dynamically sets and controls the focal length of a reflective membrane supported between a perimeter frame. A rear membrane is also supported between the perimeter frame rearward and spaced apart from a back side of the reflective membrane. The space between the membranes defines a plenum space into which a mass of gas at a first pressure is inserted. The pressure differential between the first pressure and an external pressure, such as the atmospheric pressure, causes the reflective membrane to assume a first curvature relative to a reference plane associated with the perimeter frame. This curvature defines the focal length of the reflective membrane. The focal length is dynamically controlled by changing the volume of the plenum space, thereby changing the first pressure. The system can be used to change or maintain the pressure differential and hence the front membrane curvature. The plenum volume is changed by pushing or pulling on a central section of the rear membrane using a suitable actuator. Sensing means continuously sense the location of the reflective membrane relative to the reference plane. This sensed position is compared to a reference position, and a resulting error signal, comprising the difference between the sensed position and reference position, drives the actuator in a direction to minimize the difference. A vent value compensates for temperature changes or leaks in the closed volume by allowing the pressure differential to be adjusted as required to center the working range of the actuator about the desired focal length. 13 figures.

Focus control system for stretched-membrane mirror module

DOEpatents

Butler, Barry L.; Beninga, Kelly J.

1991-01-01

A focus control system dynamically sets and controls the focal length of a reflective membrane supported between a perimeter frame. A rear membrane is also supported between the perimeter frame rearward and spaced apart from a back side of the reflective membrane. The space between the membranes defines a plenum space into which a mass of gas at a first pressure is inserted. The pressure differential between the first pressure and an external pressure, such as the atmospheric pressure, causes the reflective membrane to assume a first curvature relative to a reference plane associated with the perimeter frame. This curvature defines the focal length of the reflective membrane. The focal length is dynamically controlled by changing the volume of the plenum space, thereby changing the first pressure. The system can be used to change or maintain the pressure differential and hence the front membrane curvature. The plenum volume is changed by pushing or pulling on a central section of the rear membrane using a suitable actuator. Sensing means continuously sense the location of the reflective membrane relative to the reference plane. This sensed position is compared to a reference position, and a resulting error signal, comprising the difference between the sensed position and reference position, drives the actuator in a direction to minimize the difference. A vent value compensates for temperature changes or leaks in the closed volume by allowing the pressure differential to be adjusted as required to center the working range of the actuator about the desired focal length.

14 CFR 25.365 - Pressurized compartment loads.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Pressurized compartment loads. For airplanes with one or more pressurized compartments the following apply: (a... differential loads from zero up to the maximum relief valve setting. (b) The external pressure distribution in... zero up to the maximum allowed during landing. (d) The airplane structure must be designed to be able...

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.

A Commentary on "Differentiating Low Performance of the Gifted Learner: Achieving, Underachieving, and Selective Consuming Students"

ERIC Educational Resources Information Center

Flint, Lori J.; Ritchotte, Jennifer A.

2012-01-01

This article presents the authors' critique on "Differentiating Low Performance of the Gifted Learner: Achieving, Underachieving, and Selective Consuming Students" (Figg, Low, McCormick, & Rogers 2012). The authors of "Differentiating Low Performance of the Gifted Learner: Achieving, Underachieving, and Selective Consuming Students" endeavored to…

Leak Rate Quantification Method for Gas Pressure Seals with Controlled Pressure Differential

NASA Technical Reports Server (NTRS)

Daniels, Christopher C.; Braun, Minel J.; Oravec, Heather A.; Mather, Janice L.; Taylor, Shawn C.

2015-01-01

An enhancement to the pressure decay leak rate method with mass point analysis solved deficiencies in the standard method. By adding a control system, a constant gas pressure differential across the test article was maintained. As a result, the desired pressure condition was met at the onset of the test, and the mass leak rate and measurement uncertainty were computed in real-time. The data acquisition and control system were programmed to automatically stop when specified criteria were met. Typically, the test was stopped when a specified level of measurement uncertainty was attained. Using silicone O-ring test articles, the new method was compared with the standard method that permitted the downstream pressure to be non-constant atmospheric pressure. The two methods recorded comparable leak rates, but the new method recorded leak rates with significantly lower measurement uncertainty, statistical variance, and test duration. Utilizing this new method in leak rate quantification, projects will reduce cost and schedule, improve test results, and ease interpretation between data sets.

Pressure measurement in supersonic air flow by differential absorptive laser-induced thermal acoustics.

PubMed

Hart, Roger C; Herring, G C; Balla, R Jeffrey

2007-06-15

Nonintrusive, off-body flow barometry in Mach 2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, the streamwise velocity and static gas temperature of the same spatially resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature, and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Pressure Measurement in Supersonic Air Flow by Differential Absorptive Laser-Induced Thermal Acoustics

NASA Technical Reports Server (NTRS)

Hart, Roger C.; Herring, Gregory C.; Balla, Robert J.

2007-01-01

Nonintrusive, off-body flow barometry in Mach-2 airflow has been demonstrated in a large-scale supersonic wind tunnel using seedless laser-induced thermal acoustics (LITA). The static pressure of the gas flow is determined with a novel differential absorption measurement of the ultrasonic sound produced by the LITA pump process. Simultaneously, stream-wise velocity and static gas temperature of the same spatially-resolved sample volume were measured with this nonresonant time-averaged LITA technique. Mach number, temperature and pressure have 0.2%, 0.4%, and 4% rms agreement, respectively, in comparison with known free-stream conditions.

Controlled Tests of Eductors and Submersible Pumps

DTIC Science & Technology

1994-09-01

5 1. " 20 25 3 0 510 15 20 25 30 Time (min) Plate B63 Slurry Specific Gravity H & H Submersible Pump Clean Sand Test 1 2 I S-SG Densit MeterI SG...22 Using Differential Pressure to Measure Specific Gravity ...... .32 4-Conclusions and Recommendations ..................... 34 References...33 Figure 21. Comparison of specific gravity of the slurry as measured by the nuclear density meter and differential pressure

Balancing selection and recombination as evolutionary forces caused population genetic variations in golden pheasant MHC class I genes.

PubMed

Zeng, Qian-Qian; He, Ke; Sun, Dan-Dan; Ma, Mei-Ying; Ge, Yun-Fa; Fang, Sheng-Guo; Wan, Qiu-Hong

2016-02-18

The major histocompatibility complex (MHC) genes are vital partners in the acquired immune processes of vertebrates. MHC diversity may be directly associated with population resistance to infectious pathogens. Here, we screened for polymorphisms in exons 2 and 3 of the IA1 and IA2 genes in 12 golden pheasant populations across the Chinese mainland to characterize their genetic variation levels, to understand the effects of historical positive selection and recombination in shaping class I diversity, and to investigate the genetic structure of wild golden pheasant populations. Among 339 individual pheasants, we identified 14 IA1 alleles in exon 2 (IA1-E2), 11 IA1-E3 alleles, 27 IA2-E2 alleles, and 28 IA2-E3 alleles. The non-synonymous substitution rate was significantly greater than the synonymous substitution rate at sequences in the IA2 gene encoding putative peptide-binding sites but not in the IA1 gene; we also found more positively selected sites in IA2 than in IA1. Frequent recombination events resulted in at least 9 recombinant IA2 alleles, in accordance with the intermingling pattern of the phylogenetic tree. Although some IA alleles are widely shared among studied populations, large variation occurs in the number of IA alleles across these populations. Allele frequency analysis across 2 IA loci showed low levels of genetic differentiation among populations on small geographic scales; however, significant genetic differentiation was observed between pheasants from the northern and southern regions of the Yangtze River. Both STRUCTURE analysis and F-statistic (F ST ) value comparison classified those populations into 2 major groups: the northern region of the Yangtze River (NYR) and the southern region of the Yangtze River (SYR). More extensive polymorphisms in IA2 than IA1 indicate that IA2 has undergone much stronger positive-selection pressure during evolution. Moreover, the recombination events detected between the genes and the intermingled phylogenetic pattern indicate that interlocus recombination accounts for much of the allelic variation in IA2. Analysis of the population differentiation implied that homogenous balancing selection plays an important part in maintaining an even distribution of MHC variations. The natural barrier of the Yangtze River and heterogeneous balancing selection might help shape the NYR-SYR genetic structure in golden pheasants.

Hydrogen bonding Part 53. Correlation of differential scanning calorimetric data with IR and dissociation vapor pressure studies of transitions of hexamethonium chloride and bromide dihydrates and hexamethonium bromide monohydrate

NASA Astrophysics Data System (ADS)

Snider, Barbara L.; Harmon, Kenneth M.

1994-03-01

Differential scanning calorimetry of hexamethonium chloride dihydrate shows an endothermic transition of 2.70 kcal mol -1 at 36.81°C. This correlates well with the temperatures observed by IR spectra (36°C) and equilibrium dissociation vapor pressure studies (37°C) for the transition between Type I planar cluster and Type II extended linear HOH⋯Cl - hydrogen bonding, and with the value of 2.77 kcal mol -1 for this transition derived by Hess' law treatment of dissociation vapor pressure data. Differential scanning calorimetry of hexamethonium bromide shows a rapid endothermic transition of 2.38 kcal mol -1 at 35.15°C and a very slow endothermic transition of about 12-13 kcal mol -1 centered near 50°C. This latter endotherm corresponds to the transition between Type I and Type II HOH⋯Br - hydrogen bonding observed by IR and vapor pressure studies at 49°C. The nature of the 35.15°C endotherm is not known. Hexamethonium bromide also shows a third endotherm at 142.91°C, which presumably results from melting of hydrate in the sealed DSC cell. Combined analysis of differential scanning calorimetry and dissociation vapor pressure data predicts a value of about -13 kcal mol -1 for an exothermic disproportionation at 52°C of two hexamethonium bromide monohydrate to Type II dihydrate and anhydrous bromide.

Reactions to Media Violence: It’s in the Brain of the Beholder

PubMed Central

Alia-Klein, Nelly; Wang, Gene-Jack; Preston-Campbell, Rebecca N.; Moeller, Scott J.; Parvaz, Muhammad A.; Zhu, Wei; Jayne, Millard C.; Wong, Chris; Tomasi, Dardo; Goldstein, Rita Z.; Fowler, Joanna S.; Volkow, Nora D.

2014-01-01

Media portraying violence is part of daily exposures. The extent to which violent media exposure impacts brain and behavior has been debated. Yet there is not enough experimental data to inform this debate. We hypothesize that reaction to violent media is critically dependent on personality/trait differences between viewers, where those with the propensity for physical assault will respond to the media differently than controls. The source of the variability, we further hypothesize, is reflected in autonomic response and brain functioning that differentiate those with aggression tendencies from others. To test this hypothesis we pre-selected a group of aggressive individuals and non-aggressive controls from the normal healthy population; we documented brain, blood-pressure, and behavioral responses during resting baseline and while the groups were watching media violence and emotional media that did not portray violence. Positron Emission Tomography was used with [18F]fluoro-deoxyglucose (FDG) to image brain metabolic activity, a marker of brain function, during rest and during film viewing while blood-pressure and mood ratings were intermittently collected. Results pointed to robust resting baseline differences between groups. Aggressive individuals had lower relative glucose metabolism in the medial orbitofrontal cortex correlating with poor self-control and greater glucose metabolism in other regions of the default-mode network (DMN) where precuneus correlated with negative emotionality. These brain results were similar while watching the violent media, during which aggressive viewers reported being more Inspired and Determined and less Upset and Nervous, and also showed a progressive decline in systolic blood-pressure compared to controls. Furthermore, the blood-pressure and brain activation in orbitofrontal cortex and precuneus were differentially coupled between the groups. These results demonstrate that individual differences in trait aggression strongly couple with brain, behavioral, and autonomic reactivity to media violence which should factor into debates about the impact of media violence on the public. PMID:25208327

Reactions to media violence: it's in the brain of the beholder.

PubMed

Alia-Klein, Nelly; Wang, Gene-Jack; Preston-Campbell, Rebecca N; Moeller, Scott J; Parvaz, Muhammad A; Zhu, Wei; Jayne, Millard C; Wong, Chris; Tomasi, Dardo; Goldstein, Rita Z; Fowler, Joanna S; Volkow, Nora D

2014-01-01

Media portraying violence is part of daily exposures. The extent to which violent media exposure impacts brain and behavior has been debated. Yet there is not enough experimental data to inform this debate. We hypothesize that reaction to violent media is critically dependent on personality/trait differences between viewers, where those with the propensity for physical assault will respond to the media differently than controls. The source of the variability, we further hypothesize, is reflected in autonomic response and brain functioning that differentiate those with aggression tendencies from others. To test this hypothesis we pre-selected a group of aggressive individuals and non-aggressive controls from the normal healthy population; we documented brain, blood-pressure, and behavioral responses during resting baseline and while the groups were watching media violence and emotional media that did not portray violence. Positron Emission Tomography was used with [18F]fluoro-deoxyglucose (FDG) to image brain metabolic activity, a marker of brain function, during rest and during film viewing while blood-pressure and mood ratings were intermittently collected. Results pointed to robust resting baseline differences between groups. Aggressive individuals had lower relative glucose metabolism in the medial orbitofrontal cortex correlating with poor self-control and greater glucose metabolism in other regions of the default-mode network (DMN) where precuneus correlated with negative emotionality. These brain results were similar while watching the violent media, during which aggressive viewers reported being more Inspired and Determined and less Upset and Nervous, and also showed a progressive decline in systolic blood-pressure compared to controls. Furthermore, the blood-pressure and brain activation in orbitofrontal cortex and precuneus were differentially coupled between the groups. These results demonstrate that individual differences in trait aggression strongly couple with brain, behavioral, and autonomic reactivity to media violence which should factor into debates about the impact of media violence on the public.

Myeloma Cell Dynamics in Response to Treatment Supports a Model of Hierarchical Differentiation and Clonal Evolution.

PubMed

Tang, Min; Zhao, Rui; van de Velde, Helgi; Tross, Jennifer G; Mitsiades, Constantine; Viselli, Suzanne; Neuwirth, Rachel; Esseltine, Dixie-Lee; Anderson, Kenneth; Ghobrial, Irene M; San Miguel, Jesús F; Richardson, Paul G; Tomasson, Michael H; Michor, Franziska

2016-08-15

Since the pioneering work of Salmon and Durie, quantitative measures of tumor burden in multiple myeloma have been used to make clinical predictions and model tumor growth. However, such quantitative analyses have not yet been performed on large datasets from trials using modern chemotherapy regimens. We analyzed a large set of tumor response data from three randomized controlled trials of bortezomib-based chemotherapy regimens (total sample size n = 1,469 patients) to establish and validate a novel mathematical model of multiple myeloma cell dynamics. Treatment dynamics in newly diagnosed patients were most consistent with a model postulating two tumor cell subpopulations, "progenitor cells" and "differentiated cells." Differential treatment responses were observed with significant tumoricidal effects on differentiated cells and less clear effects on progenitor cells. We validated this model using a second trial of newly diagnosed patients and a third trial of refractory patients. When applying our model to data of relapsed patients, we found that a hybrid model incorporating both a differentiation hierarchy and clonal evolution best explains the response patterns. The clinical data, together with mathematical modeling, suggest that bortezomib-based therapy exerts a selection pressure on myeloma cells that can shape the disease phenotype, thereby generating further inter-patient variability. This model may be a useful tool for improving our understanding of disease biology and the response to chemotherapy regimens. Clin Cancer Res; 22(16); 4206-14. ©2016 AACR. ©2016 American Association for Cancer Research.

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.

Associations between MHC genes and Puumala virus infection in Myodes glareolus are detected in wild populations, but not from experimental infection data.

PubMed

Guivier, Emmanuel; Galan, Maxime; Malé, Pierre-Jean G; Kallio, Eva R; Voutilainen, Liina; Henttonen, Heikki; Olsson, Gert E; Lundkvist, Ake; Tersago, Katrien; Augot, Denis; Cosson, Jean-François; Charbonnel, Nathalie

2010-10-01

We analysed the influence of MHC class II Dqa and Drb genes on Puumala virus (PUUV) infection in bank voles (Myodes glareolus). We considered voles sampled in five European localities or derived from a previous experiment that showed variable infection success of PUUV. The genetic variation observed in the Dqa and Drb genes was assessed by using single-strand conformation polymorphism and pyrosequencing methods, respectively. Patterns were compared with those obtained from 13 microsatellites. We revealed significant genetic differentiation between PUUV-seronegative and -seropositive bank voles sampled in wild populations, at the Drb gene only. The absence of genetic differentiation observed at neutral microsatellites confirmed the important role of selective pressures in shaping these Drb patterns. Also, we found no significant associations between infection success and MHC alleles among laboratory-colonized bank voles, which is explained by a loss of genetic variability that occurred during the captivity of these voles.

Demographic drivers of age-dependent sexual selection.

PubMed

Martin, A M; Festa-Bianchet, M; Coltman, D W; Pelletier, F

2016-07-01

Sexual selection has a critical role in evolution, and it is fundamental to identify what ecological factors drive its variation. Disentangling the ecological correlates of sexual selection over the long term, however, is challenging and has rarely been done in nature. We sought to assess how demographic changes influenced the intensity, direction and form of sexual selection and whether selective pressures varied with age. We tested whether breeder sex ratio, number of competitors and age structure influenced selection differentials on horn length of wild bighorn rams (Ovis canadensis) of different age classes on Ram Mountain, Alberta. We used 21 years of data including a detailed pedigree, demographic parameters and repeated morphological measurements. Sexual selection on horn length of males of all ages was directional and positive. Selection intensity increased with the number of competitors, reflecting male-male encounter rate during the rut, but was independent of breeder sex ratio or age structure. This result can also be linked to changes in population size because the number of competitors was highly correlated to total number of sheep. This demographic effect likely arises from age-dependent mating tactics. Males aged 2-4 years are weakly competitive and experienced stronger sexual selection as they accounted for a greater proportion of all males. Selection experienced by mature males appeared independent of demography. Our study provides a rare description of the demographic determinants of sexual selection in nature. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Differentiated adaptive evolution, episodic relaxation of selective constraints, and pseudogenization of umami and sweet taste genes TAS1Rs in catarrhine primates.

PubMed

Liu, Guangjian; Walter, Lutz; Tang, Suni; Tan, Xinxin; Shi, Fanglei; Pan, Huijuan; Roos, Christian; Liu, Zhijin; Li, Ming

2014-01-01

Umami and sweet tastes are two important basic taste perceptions that allow animals to recognize diets with nutritious carbohydrates and proteins, respectively. Until recently, analyses of umami and sweet taste were performed on various domestic and wild animals. While most of these studies focused on the pseudogenization of taste genes, which occur mostly in carnivores and species with absolute feeding specialization, omnivores and herbivores were more or less neglected. Catarrhine primates are a group of herbivorous animals (feeding mostly on plants) with significant divergence in dietary preference, especially the specialized folivorous Colobinae. Here, we conducted the most comprehensive investigation to date of selection pressure on sweet and umami taste genes (TAS1Rs) in catarrhine primates to test whether specific adaptive evolution occurred during their diversification, in association with particular plant diets. We documented significant relaxation of selective constraints on sweet taste gene TAS1R2 in the ancestral branch of Colobinae, which might correlate with their unique ingestion and digestion of leaves. Additionally, we identified positive selection acting on Cercopithecidae lineages for the umami taste gene TAS1R1, on the Cercopithecinae and extant Colobinae and Hylobatidae lineages for TAS1R2, and on Macaca lineages for TAS1R3. Our research further identified several site mutations in Cercopithecidae, Colobinae and Pygathrix, which were detected by previous studies altering the sensitivity of receptors. The positively selected sites were located mostly on the extra-cellular region of TAS1Rs. Among these positively selected sites, two vital sites for TAS1R1 and four vital sites for TAS1R2 in extra-cellular region were identified as being responsible for the binding of certain sweet and umami taste molecules through molecular modelling and docking. Our results suggest that episodic and differentiated adaptive evolution of TAS1Rs pervasively occurred in catarrhine primates, most concentrated upon the extra-cellular region of TAS1Rs.

High Precision Pressure Measurement with a Funnel

ERIC Educational Resources Information Center

Lopez-Arias, T.; Gratton, L. M.; Oss, S.

2008-01-01

A simple experimental device for high precision differential pressure measurements is presented. Its working mechanism recalls that of a hydraulic press, where pressure is supplied by insufflating air under a funnel. As an application, we measure air pressure inside a soap bubble. The soap bubble is inflated and connected to a funnel which is…

Dynamic Hydrostatic Pressure Promotes Differentiation of Human Dental Pulp Stem Cells

PubMed Central

Yu, V; Damek-Poprawa, M.; Nicoll, S. B.; Akintoye, S.O.

2009-01-01

The masticatory apparatus absorbs high occlusal forces, but uncontrolled parafunctional or orthodontic forces damage periodontal ligament (PDL), cause pulpal calcification, pulp necrosis and tooth loss. Morphology and functional differentiation of connective tissue cells can be controlled by mechanical stimuli but effects of uncontrolled forces on intra-pulpal homeostasis and ability of dental pulp stem cells (DPSCs) to withstand direct external forces are unclear. Using dynamic hydrostatic pressure (HSP), we tested the hypothesis that direct HSP disrupts DPSC survival and odontogenic differentiation. DPSCs from four teenage patients were subjected to HSP followed by assessment of cell adhesion, survival and recovery capacity based on odontogenic differentiation, mineralization and responsiveness to bone morphogenetic protein-2 (BMP-2). HSP down-regulated DPSC adhesion and survival but promoted differentiation by increasing mineralization, in vivo hard tissue regeneration and BMP-2 responsiveness despite reduced cell numbers. HSP-treated DPSCs displayed enhanced odontogenic differentiation, an indication of favorable recovery from HSP-induced cellular stress. PMID:19555657

Disturbance torque rejection properties of the NASA/JPL 70-meter antenna axis servos

NASA Technical Reports Server (NTRS)

Hill, R. E.

1989-01-01

Analytic methods for evaluating pointing errors caused by external disturbance torques are developed and applied to determine the effects of representative values of wind and friction torque. The expressions relating pointing errors to disturbance torques are shown to be strongly dependent upon the state estimator parameters, as well as upon the state feedback gain and the flow versus pressure characteristics of the hydraulic system. Under certain conditions, when control is derived from an uncorrected estimate of integral position error, the desired type 2 servo properties are not realized and finite steady-state position errors result. Methods for reducing these errors to negligible proportions through the proper selection of control gain and estimator correction parameters are demonstrated. The steady-state error produced by a disturbance torque is found to be directly proportional to the hydraulic internal leakage. This property can be exploited to provide a convenient method of determining system leakage from field measurements of estimator error, axis rate, and hydraulic differential pressure.

A Model for the Oxidation of Carbon Silicon Carbide Composite Structures

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2004-01-01

A mathematical theory and an accompanying numerical scheme have been developed for predicting the oxidation behavior of carbon silicon carbide (C/SiC) composite structures. The theory is derived from the mechanics of the flow of ideal gases through a porous solid. The result of the theoretical formulation is a set of two coupled nonlinear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations are solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of the spatial location and time. The local rate of carbon oxidation is determined using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The nonlinear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual method, allowing for the solution of the differential equations numerically. The numerical method is demonstrated by utilizing the method to model the carbon oxidation and weight loss behavior of C/SiC specimens during thermogravimetric experiments. The numerical method is used to study the physics of carbon oxidation in carbon silicon carbide composites.

Adaptive divergence in a scleractinian coral: physiological adaptation of Seriatopora hystrix to shallow and deep reef habitats

PubMed Central

2011-01-01

Background Divergent natural selection across environmental gradients has been acknowledged as a major driver of population and species divergence, however its role in the diversification of scleractinian corals remains poorly understood. Recently, it was demonstrated that the brooding coral Seriatopora hystrix and its algal endosymbionts (Symbiodinium) are genetically partitioned across reef environments (0-30 m) on the far northern Great Barrier Reef. Here, we explore the potential mechanisms underlying this differentiation and assess the stability of host-symbiont associations through a reciprocal transplantation experiment across habitats ('Back Reef', 'Upper Slope' and 'Deep Slope'), in combination with molecular (mtDNA and ITS2-DGGE) and photo-physiological analyses (respirometry and HPLC). Results The highest survival rates were observed for native transplants (measured 14 months after transplantation), indicating differential selective pressures between habitats. Host-symbiont assemblages remained stable during the experimental duration, demonstrating that the ability to "shuffle" or "switch" symbionts is restricted in S. hystrix. Photo-physiological differences were observed between transplants originating from the shallow and deep habitats, with indirect evidence of an increased heterotrophic capacity in native deep-water transplants (from the 'Deep Slope' habitat). Similar photo-acclimatisation potential was observed between transplants originating from the two shallow habitats ('Back Reef' and 'Upper Slope'), highlighting that their genetic segregation over depth may be due to other, non-photo-physiological traits under selection. Conclusions This study confirms that the observed habitat partitioning of S. hystrix (and associated Symbiodinium) is reflective of adaptive divergence along a depth gradient. Gene flow appears to be reduced due to divergent selection, highlighting the potential role of ecological mechanisms, in addition to physical dispersal barriers, in the diversification of scleractinian corals and their associated Symbiodinium. PMID:22004364

Water temperature, not fish morph, determines parasite infections of sympatric Icelandic threespine sticklebacks (Gasterosteus aculeatus).

PubMed

Karvonen, Anssi; Kristjánsson, Bjarni K; Skúlason, Skúli; Lanki, Maiju; Rellstab, Christian; Jokela, Jukka

2013-06-01

Parasite communities of fishes are known to respond directly to the abiotic environment of the host, for example, to water quality and water temperature. Biotic factors are also important as they affect the exposure profile through heterogeneities in parasite distribution in the environment. Parasites in a particular environment may pose a strong selection on fish. For example, ecological differences in selection by parasites have been hypothesized to facilitate evolutionary differentiation of freshwater fish morphs specializing on different food types. However, as parasites may also respond directly to abiotic environment the parasite risk does not depend only on biotic features of the host environment. It is possible that different morphs experience specific selection gradients by parasites but it is not clear how consistent the selection is when abiotic factors change. We examined parasite pressure in sympatric morphs of threespine stickleback (Gasterosteus aculeatus) across a temperature gradient in two large Icelandic lakes, Myvatn and Thingvallavatn. Habitat-specific temperature gradients in these lakes are opposite. Myvatn lava rock morph lives in a warm environment, while the mud morph lives in the cold. In Thingvallavatn, the lava rock morph lives in a cold environment and the mud morph in a warm habitat. We found more parasites in fish living in higher temperature in both lakes, independent of the fish morph, and this pattern was similar for the two dominating parasite taxa, trematodes and cestodes. However, at the same time, we also found higher parasite abundance in a third morph living in deep cold-water habitat in Thingvallavatn compared to the cold-water lava morph, indicating strong effect of habitat-specific biotic factors. Our results suggest complex interactions between water temperature and biotic factors in determining the parasite community structure, a pattern that may have implications for differentiation of stickleback morphs.

The differential path phase comparison method for determining pressure derivatives of elastic constants of solids

NASA Astrophysics Data System (ADS)

Peselnick, L.

1982-08-01

An ultrasonic method is presented which combines features of the differential path and the phase comparison methods. The proposed differential path phase comparison method, referred to as the `hybrid' method for brevity, eliminates errors resulting from phase changes in the bond between the sample and buffer rod. Define r(P) [and R(P)] as the square of the normalized frequency for cancellation of sample waves for shear [and for compressional] waves. Define N as the number of wavelengths in twice the sample length. The pressure derivatives r'(P) and R' (P) for samples of Alcoa 2024-T4 aluminum were obtained by using the phase comparison and the hybrid methods. The values of the pressure derivatives obtained by using the phase comparison method show variations by as much as 40% for small values of N (N < 50). The pressure derivatives as determined from the hybrid method are reproducible to within ±2% independent of N. The values of the pressure derivatives determined by the phase comparison method for large N are the same as those determined by the hybrid method. Advantages of the hybrid method are (1) no pressure dependent phase shift at the buffer-sample interface, (2) elimination of deviatoric stress in the sample portion of the sample assembly with application of hydrostatic pressure, and (3) operation at lower ultrasonic frequencies (for comparable sample lengths), which eliminates detrimental high frequency ultrasonic problems. A reduction of the uncertainties of the pressure derivatives of single crystals and of low porosity polycrystals permits extrapolation of such experimental data to deeper mantle depths.

Fluidic angular velocity sensor

NASA Technical Reports Server (NTRS)

Berdahl, C. M. (Inventor)

1986-01-01

A fluidic sensor providing a differential pressure signal proportional to the angular velocity of a rotary input is described. In one embodiment the sensor includes a fluid pump having an impeller coupled to a rotary input. A housing forming a constricting fluid flow chamber is connected to the fluid input of the pump. The housing is provided with a fluid flow restrictive input to the flow chamber and a port communicating with the interior of the flow chamber. The differential pressure signal measured across the flow restrictive input is relatively noise free and proportional to the square of the angular velocity of the impeller. In an alternative embodiment, the flow chamber has a generally cylindrical configuration and plates having flow restrictive apertures are disposed within the chamber downstream from the housing port. In this embodiment, the differential pressure signal is found to be approximately linear with the angular velocity of the impeller.

Method for automatically scramming a nuclear reactor

DOEpatents

Ougouag, Abderrafi M.; Schultz, Richard R.; Terry, William K.

2005-12-27

An automatically scramming nuclear reactor system. One embodiment comprises a core having a coolant inlet end and a coolant outlet end. A cooling system operatively associated with the core provides coolant to the coolant inlet end and removes heated coolant from the coolant outlet end, thus maintaining a pressure differential therebetween during a normal operating condition of the nuclear reactor system. A guide tube is positioned within the core with a first end of the guide tube in fluid communication with the coolant inlet end of the core, and a second end of the guide tube in fluid communication with the coolant outlet end of the core. A control element is positioned within the guide tube and is movable therein between upper and lower positions, and automatically falls under the action of gravity to the lower position when the pressure differential drops below a safe pressure differential.

Bax deficiency prolongs cerebellar neurogenesis, accelerates medulloblastoma formation and paradoxically increases both malignancy and differentiation.

PubMed

Garcia, I; Crowther, A J; Gama, V; Miller, C R; Miller, C Ryan; Deshmukh, M; Gershon, T R

2013-05-02

Neurogenesis requires negative regulation through differentiation of progenitors or their programmed cell death (PCD). Growth regulation is particularly important in the postnatal cerebellum, where excessive progenitor proliferation promotes medulloblastoma, the most common malignant brain tumor in children. We present evidence that PCD operates alongside differentiation to regulate cerebellar granule neuron progenitors (CGNPs) and to prevent medulloblastoma. Here, we show that genetic deletion of pro-apoptotic Bax disrupts regulation of cerebellar neurogenesis and promotes medulloblastoma formation. In Bax(-/-) mice, the period of neurogenesis was extended into the third week of postnatal life, and ectopic neurons and progenitors collected in the molecular layer of the cerebellum and adjacent tectum. Importantly, genetic deletion of Bax in medulloblastoma-prone ND2:SmoA1 transgenic mice greatly accelerated tumorigenesis. Bax-deficient medulloblastomas exhibited strikingly distinct pathology, with reduced apoptosis, increased neural differentiation and tectal migration. Comparing Bax(+/+) and Bax(-/-) medulloblastomas, we were able to identify upregulation of Bcl-2 and nuclear exclusion of p27 as tumorigenic changes that are required to mitigate the tumor suppressive effect of Bax. Studies on human tumors confirmed the importance of modulating Bax in medulloblastoma pathogenesis. Our results demonstrate that Bax-dependent apoptosis regulates postnatal cerebellar neurogenesis, suppresses medulloblastoma formation and imposes selective pressure on tumors that form. Functional resistance to Bax-mediated apoptosis, required for medulloblastoma tumorigenesis, may be a tumor-specific vulnerability to be exploited for therapeutic benefit.

Adaptive genomic divergence under high gene flow between freshwater and brackish-water ecotypes of prickly sculpin (Cottus asper) revealed by Pool-Seq.

PubMed

Dennenmoser, Stefan; Vamosi, Steven M; Nolte, Arne W; Rogers, Sean M

2017-01-01

Understanding the genomic basis of adaptive divergence in the presence of gene flow remains a major challenge in evolutionary biology. In prickly sculpin (Cottus asper), an abundant euryhaline fish in northwestern North America, high genetic connectivity among brackish-water (estuarine) and freshwater (tributary) habitats of coastal rivers does not preclude the build-up of neutral genetic differentiation and emergence of different life history strategies. Because these two habitats present different osmotic niches, we predicted high genetic differentiation at known teleost candidate genes underlying salinity tolerance and osmoregulation. We applied whole-genome sequencing of pooled DNA samples (Pool-Seq) to explore adaptive divergence between two estuarine and two tributary habitats. Paired-end sequence reads were mapped against genomic contigs of European Cottus, and the gene content of candidate regions was explored based on comparisons with the threespine stickleback genome. Genes showing signals of repeated differentiation among brackish-water and freshwater habitats included functions such as ion transport and structural permeability in freshwater gills, which suggests that local adaptation to different osmotic niches might contribute to genomic divergence among habitats. Overall, the presence of both repeated and unique signatures of differentiation across many loci scattered throughout the genome is consistent with polygenic adaptation from standing genetic variation and locally variable selection pressures in the early stages of life history divergence. © 2016 John Wiley & Sons Ltd.

Analytic Formulation and Numerical Implementation of an Acoustic Pressure Gradient Prediction

NASA Technical Reports Server (NTRS)

Lee, Seongkyu; Brentner, Kenneth S.; Farassat, F.; Morris, Philip J.

2008-01-01

Two new analytical formulations of the acoustic pressure gradient have been developed and implemented in the PSU-WOPWOP rotor noise prediction code. The pressure gradient can be used to solve the boundary condition for scattering problems and it is a key aspect to solve acoustic scattering problems. The first formulation is derived from the gradient of the Ffowcs Williams-Hawkings (FW-H) equation. This formulation has a form involving the observer time differentiation outside the integrals. In the second formulation, the time differentiation is taken inside the integrals analytically. This formulation avoids the numerical time differentiation with respect to the observer time, which is computationally more efficient. The acoustic pressure gradient predicted by these new formulations is validated through comparison with available exact solutions for a stationary and moving monopole sources. The agreement between the predictions and exact solutions is excellent. The formulations are applied to the rotor noise problems for two model rotors. A purely numerical approach is compared with the analytical formulations. The agreement between the analytical formulations and the numerical method is excellent for both stationary and moving observer cases.

Pressure overload differentially affects respiratory capacity in interfibrillar and subsarcolemmal mitochondria.

PubMed

Schwarzer, Michael; Schrepper, Andrea; Amorim, Paulo A; Osterholt, Moritz; Doenst, Torsten

2013-02-15

Years ago a debate arose as to whether two functionally different mitochondrial subpopulations, subsarcolemmal mitochondria (SSM) and interfibrillar mitochondria (IFM), exist in heart muscle. Nowadays potential differences are often ignored. Presumably, SSM are providing ATP for basic cell function, whereas IFM provide energy for the contractile apparatus. We speculated that two distinguishable subpopulations exist that are differentially affected by pressure overload. Male Sprague-Dawley rats were subjected to transverse aortic constriction for 20 wk or sham operation. Contractile function was assessed by echocardiography. Heart tissue was analyzed by electron microscopy. Mitochondria were isolated by differential centrifugation, and respiratory capacity was analyzed using a Clark electrode. Pressure overload induced left ventricular hypertrophy with increased posterior wall diameter and impaired contractile function. Mitochondrial state 3 respiration in control was 50% higher in IFM than in SSM. Pressure overload significantly impaired respiratory rates in both IFM and SSM, but in SSM to a lower extent. As a result, there were no differences between SSM and IFM after 20 wk of pressure overload. Pressure overload reduced total citrate synthase activity, suggesting reduced total mitochondrial content. Electron microscopy revealed normal morphology of mitochondria but reduced total mitochondrial volume density. In conclusion, IFM show greater respiratory capacity in the healthy rat heart and a greater depression of respiratory capacity by pressure overload than SSM. The differences in respiratory capacity of cardiac IFM and SSM in healthy hearts are eliminated with pressure overload-induced heart failure. The strong effect of pressure overload on IFM together with the simultaneous appearance of mitochondrial and contractile dysfunction may support the notion of IFM primarily producing ATP for contractile function.

Role of Re-entry Tears on the Dynamics of Type B Dissection Flap.

PubMed

Canchi, Saranya; Guo, Xiaomei; Phillips, Matt; Berwick, Zachary; Kratzberg, Jarin; Krieger, Joshua; Roeder, Blayne; Haulon, Stephan; Chambers, Sean; Kassab, Ghassan S

2018-01-01

Mortality during follow-up after acute Type B aortic dissection is substantial with aortic expansion observed in over 59% of the patients. Lumen pressure differential is considered a prime contributing factor for aortic dilation after propagation. The objective of the study was to evaluate the relationship between changes in vessel geometry with and without lumen pressure differential post propagation in an ex vivo porcine model with comparison with patient clinical data. A pulse duplicator system was utilized to propagate the dissection within descending thoracic porcine aortic vessels for set proximal (%circumference of the entry tear: 40%, axial length: 2 cm) and re-entry (50% of distal vessel circumference) tear geometry. Measurements of lumen pressure differential were made along with quantification of vessel geometry (n = 16). The magnitude of mean lumen pressure difference measured after propagation was low (~ 5 mmHg) with higher pressures measured in false lumen and as anticipated the pressure difference approached zero after the creation of distal re-entry tear. False lumen Dissection Ratio (FDR) defined as arc length of dissected wall divided by arc length of dissection flap, had mean value of 1.59 ± 0.01 at pressure of 120/80 mmHg post propagation with increasing values with increase in pulse pressure that was not rescued with the creation of distal re-entry tear (p < 0.01). An average FDR of 1.87 ± 0.27 was measured in patients with acute Type B dissection. Higher FDR value (FDR = 1 implies zero dissection) in the presence of distal re-entry tear demonstrates an acute change in vessel morphology in response to the dissection independent of local pressure changes challenges the re-apposition of the aortic wall.

Sex Differences: A Resultant of an Evolutionary Pressure?

PubMed

Della Torre, Sara; Maggi, Adriana

2017-03-07

Spurred by current research policy, we are witnessing a significant growth in the number of studies that observe and describe sexual diversities in human physiology and sex prevalence in a large number of pathologies. Yet we are far from the comprehension of the mechanisms underpinning these differences, which are the result of a long evolutionary history. This Essay is meant to underline female reproductive function as a driver for the positive selection of the specific physiological features that explain male and female differential susceptibility to diseases and metabolic disturbances, in particular. A clear understanding of the causes underlying sexual dimorphisms in the physio-pathology is crucial for precision medicine. Copyright © 2017 Elsevier Inc. All rights reserved.

Pressure suppression containment system for boiling water reactor

DOEpatents

Gluntz, Douglas M.; Nesbitt, Loyd B.

1997-01-01

A system for suppressing the pressure inside the containment of a BWR following a postulated accident. A piping subsystem is provided which features a main process pipe that communicates the wetwell airspace to a connection point downstream of the guard charcoal bed in an offgas system and upstream of the main bank of delay charcoal beds which give extensive holdup to offgases. The main process pipe is fitted with both inboard and outboard containment isolation valves. Also incorporated in the main process pipe is a low-differential-pressure rupture disk which prevents any gas outflow in this piping whatsoever until or unless rupture occurs by virtue of pressure inside this main process pipe on the wetwell airspace side of the disk exceeding the design opening (rupture) pressure differential. The charcoal holds up the radioactive species in the noncondensable gas from the wetwell plenum by adsorption, allowing time for radioactive decay before the gas is vented to the environs.

Thermal and structural alternations in CuAlMnNi shape memory alloy by the effect of different pressure applications

NASA Astrophysics Data System (ADS)

Canbay, Canan Aksu; Polat, Tercan

2017-09-01

In this work the effects of the applied pressure on the characteristic transformation temperatures, the high temperature order-disorder phase transitions, the variation in diffraction peaks and the surface morphology of the CuAlMnNi shape memory alloy was investigated. The evolution of the transformation temperatures was studied by differential scanning calorimetry (DSC) with different heating and cooling rates. The differential thermal analysis measurements were performed to obtain the ordered-disordered phase transformations from room temperature to 900 °C. The characteristic transformation temperatures and the thermodynamic parameters were highly sensitive to variations in the applied pressure and also the applied pressure affected the thermodynamic parameters. The activation energy of the sample according to applied pressure values calculated by Kissinger method. The structural changes of the samples were studied by X-ray diffraction (XRD) measurements and by optical microscope observations at room temperature.

Apparatus and process to eliminate diffusional limitations in a membrane biological reactor by pressure cycling

DOEpatents

Efthymiou, George S.; Shuler, Michael L.

1989-08-29

An improved multilayer continuous biological membrane reactor and a process to eliminate diffusional limitations in membrane reactors in achieved by causing a convective flux of nutrient to move into and out of an immobilized biocatalyst cell layer. In a pressure cycled mode, by increasing and decreasing the pressure in the respective layers, the differential pressure between the gaseous layer and the nutrient layer is alternately changed from positive to negative. The intermittent change in pressure differential accelerates the transfer of nutrient from the nutrient layers to the biocatalyst cell layer, the transfer of product from the cell layer to the nutrient layer and the transfer of byproduct gas from the cell layer to the gaseous layer. Such intermittent cycling substantially eliminates mass transfer gradients in diffusion inhibited systems and greatly increases product yield and throughput in both inhibited and noninhibited systems.

Differential absorption lidar measurements of atmospheric temperature and pressure profiles

NASA Technical Reports Server (NTRS)

Korb, C. L.

1981-01-01

The theory and methodology of using differential absorption lidar techniques for the remote measurement of atmospheric pressure profiles, surface pressure, and temperature profiles from ground, air, and space-based platforms are presented. Pressure measurements are effected by means of high resolution measurement of absorption at the edges of the oxygen A band lines where absorption is pressure dependent due to collisional line broadening. Temperature is assessed using measurements of the absorption at the center of the oxygen A band line originating from a quantum state with high ground state energy. The population of the state is temperature dependent, allowing determination of the temperature through the Boltzmann term. The results of simulations of the techniques using Voigt profile and variational analysis are reported for ground-based, airborne, and Shuttle-based systems. Accuracies in the 0.5-1.0 K and 0.1-0.3% range are projected.

Safety Analysis LOX-30 Liquid Oxygen Generator.

DTIC Science & Technology

1978-05-22

Valve. Protects the LOX—30 plant against over—pressurization. Valve opens at approximately 100 psig. (3) Oil Pressure Switch . Protects compressor...29 psig. d. Cryogenerator. •0 (1) 011 Pressure Switch . Prevents cryogenerator damage due to inadequate lubrication. The switch initiates system shut...when helium pressure is less than 200 psig, will result in compressor shut—down within ten seconds. (2) Differential Pressure Switch (2 each). These

Duplex sampling apparatus and method

DOEpatents

Brown, Paul E.; Lloyd, Robert

1992-01-01

An improved apparatus is provided for sampling a gaseous mixture and for measuring mixture components. The apparatus includes two sampling containers connected in series serving as a duplex sampling apparatus. The apparatus is adapted to independently determine the amounts of condensable and noncondensable gases in admixture from a single sample. More specifically, a first container includes a first port capable of selectively connecting to and disconnecting from a sample source and a second port capable of selectively connecting to and disconnecting from a second container. A second container also includes a first port capable of selectively connecting to and disconnecting from the second port of the first container and a second port capable of either selectively connecting to and disconnecting from a differential pressure source. By cooling a mixture sample in the first container, the condensable vapors form a liquid, leaving noncondensable gases either as free gases or dissolved in the liquid. The condensed liquid is heated to drive out dissolved noncondensable gases, and all the noncondensable gases are transferred to the second container. Then the first and second containers are separated from one another in order to separately determine the amount of noncondensable gases and the amount of condensable gases in the sample.

Process for the production of liquid hydrocarbons

DOEpatents

Bhatt, Bharat Lajjaram; Engel, Dirk Coenraad; Heydorn, Edward Clyde; Senden, Matthijis Maria Gerardus

2006-06-27

The present invention concerns a process for the preparation of liquid hydrocarbons which process comprises contacting synthesis gas with a slurry of solid catalyst particles and a liquid in a reactor vessel by introducing the synthesis gas at a low level into the slurry at conditions suitable for conversion of the synthesis gas into liquid hydrocarbons, the solid catalyst particles comprising a catalytic active metal selected from cobalt or iron on a porous refractory oxide carrier, preferably selected from silica, alumina, titania, zirconia or mixtures thereof, the catalyst being present in an amount between 10 and 40 vol. percent based on total slurry volume liquids and solids, and separating liquid material from the solid catalyst particles by using a filtration system comprising an asymmetric filtration medium (the selective side at the slurry side), in which filtration system the average pressure differential over the filtration medium is at least 0.1 bar, in which process the particle size distribution is such that at least a certain amount of the catalyst particles is smaller than the average pore size of the selective layer of the filtration medium. The invention also comprises an apparatus to carry out the process described above.

Determination of the heat of hydride formation/decomposition by high-pressure differential scanning calorimetry (HP-DSC).

PubMed

Rongeat, Carine; Llamas-Jansa, Isabel; Doppiu, Stefania; Deledda, Stefano; Borgschulte, Andreas; Schultz, Ludwig; Gutfleisch, Oliver

2007-11-22

Among the thermodynamic properties of novel materials for solid-state hydrogen storage, the heat of formation/decomposition of hydrides is the most important parameter to evaluate the stability of the compound and its temperature and pressure of operation. In this work, the desorption and absorption behaviors of three different classes of hydrides are investigated under different hydrogen pressures using high-pressure differential scanning calorimetry (HP-DSC). The HP-DSC technique is used to estimate the equilibrium pressures as a function of temperature, from which the heat of formation is derived. The relevance of this procedure is demonstrated for (i) magnesium-based compounds (Ni-doped MgH2), (ii) Mg-Co-based ternary hydrides (Mg-CoHx) and (iii) Alanate complex hydrides (Ti-doped NaAlH4). From these results, it can be concluded that HP-DSC is a powerful tool to obtain a good approximation of the thermodynamic properties of hydride compounds by a simple and fast study of desorption and absorption properties under different pressures.

Genome-wide analysis of ivermectin response by Onchocerca volvulus reveals that genetic drift and soft selective sweeps contribute to loss of drug sensitivity

PubMed Central

Nana-Djeunga, Hugues C.; Kengne-Ouafo, Jonas A.; Pion, Sébastien D. S.; Bopda, Jean; Kamgno, Joseph; Wanji, Samuel; Che, Hua; Kuesel, Annette C.; Walker, Martin; Basáñez, Maria-Gloria; Boakye, Daniel A.; Osei-Atweneboana, Mike Y.; Boussinesq, Michel; Prichard, Roger K.; Grant, Warwick N.

2017-01-01

Background Treatment of onchocerciasis using mass ivermectin administration has reduced morbidity and transmission throughout Africa and Central/South America. Mass drug administration is likely to exert selection pressure on parasites, and phenotypic and genetic changes in several Onchocerca volvulus populations from Cameroon and Ghana—exposed to more than a decade of regular ivermectin treatment—have raised concern that sub-optimal responses to ivermectin's anti-fecundity effect are becoming more frequent and may spread. Methodology/Principal findings Pooled next generation sequencing (Pool-seq) was used to characterise genetic diversity within and between 108 adult female worms differing in ivermectin treatment history and response. Genome-wide analyses revealed genetic variation that significantly differentiated good responder (GR) and sub-optimal responder (SOR) parasites. These variants were not randomly distributed but clustered in ~31 quantitative trait loci (QTLs), with little overlap in putative QTL position and gene content between the two countries. Published candidate ivermectin SOR genes were largely absent in these regions; QTLs differentiating GR and SOR worms were enriched for genes in molecular pathways associated with neurotransmission, development, and stress responses. Finally, single worm genotyping demonstrated that geographic isolation and genetic change over time (in the presence of drug exposure) had a significantly greater role in shaping genetic diversity than the evolution of SOR. Conclusions/Significance This study is one of the first genome-wide association analyses in a parasitic nematode, and provides insight into the genomics of ivermectin response and population structure of O. volvulus. We argue that ivermectin response is a polygenically-determined quantitative trait (QT) whereby identical or related molecular pathways but not necessarily individual genes are likely to determine the extent of ivermectin response in different parasite populations. Furthermore, we propose that genetic drift rather than genetic selection of SOR is the underlying driver of population differentiation, which has significant implications for the emergence and potential spread of SOR within and between these parasite populations. PMID:28746337

HSP90 Inhibition and Cellular Stress Elicits Phenotypic Plasticity in Hematopoietic Differentiation

PubMed Central

Lawag, Abdalla A.; Napper, Jennifer M.; Hunter, Caroline A.; Bacon, Nickolas A.; Deskins, Seth; El-hamdani, Manaf; Govender, Sarah-Leigh; Koc, Emine C.

2017-01-01

Abstract Cancer cells exist in a state of Darwinian selection using mechanisms that produce changes in gene expression through genetic and epigenetic alteration to facilitate their survival. Cellular plasticity, or the ability to alter cellular phenotype, can assist in survival of premalignant cells as they progress to full malignancy by providing another mechanism of adaptation. The connection between cellular stress and the progression of cancer has been established, although the details of the mechanisms have yet to be fully elucidated. The molecular chaperone HSP90 is often upregulated in cancers as they progress, presumably to allow cancer cells to deal with misfolded proteins and cellular stress associated with transformation. The objective of this work is to test the hypothesis that inhibition of HSP90 results in increased cell plasticity in mammalian systems that can confer a greater adaptability to selective pressures. The approach used is a murine in vitro model system of hematopoietic differentiation that utilizes a murine hematopoietic stem cell line, erythroid myeloid lymphoid (EML) clone 1, during their maturation from stem cells to granulocytic progenitors. During the differentiation protocol, 80%–90% of the cells die when placed in medium where the major growth factor is granulocyte–macrophage-colony stimulating factor. Using this selection point model, EML cells exhibit increases in cellular plasticity when they are better able to adapt to this medium and survive. Increases in cellular plasticity were found to occur upon exposure to geldanamycin to inhibit HSP90, when subjected to various forms of cellular stress, or inhibition of histone acetylation. Furthermore, we provide evidence that the cellular plasticity associated with inhibition of HSP90 in this model involves epigenetic mechanisms and is dependent upon high levels of stem cell factor signaling. This work provides evidence for a role of HSP90 and cellular stress in inducing phenotypic plasticity in mammalian systems that has new implications for cellular stress in progression and evolution of cancer. PMID:28910138

HSP90 Inhibition and Cellular Stress Elicits Phenotypic Plasticity in Hematopoietic Differentiation.

PubMed

Lawag, Abdalla A; Napper, Jennifer M; Hunter, Caroline A; Bacon, Nickolas A; Deskins, Seth; El-Hamdani, Manaf; Govender, Sarah-Leigh; Koc, Emine C; Sollars, Vincent E

2017-10-01

Cancer cells exist in a state of Darwinian selection using mechanisms that produce changes in gene expression through genetic and epigenetic alteration to facilitate their survival. Cellular plasticity, or the ability to alter cellular phenotype, can assist in survival of premalignant cells as they progress to full malignancy by providing another mechanism of adaptation. The connection between cellular stress and the progression of cancer has been established, although the details of the mechanisms have yet to be fully elucidated. The molecular chaperone HSP90 is often upregulated in cancers as they progress, presumably to allow cancer cells to deal with misfolded proteins and cellular stress associated with transformation. The objective of this work is to test the hypothesis that inhibition of HSP90 results in increased cell plasticity in mammalian systems that can confer a greater adaptability to selective pressures. The approach used is a murine in vitro model system of hematopoietic differentiation that utilizes a murine hematopoietic stem cell line, erythroid myeloid lymphoid (EML) clone 1, during their maturation from stem cells to granulocytic progenitors. During the differentiation protocol, 80%-90% of the cells die when placed in medium where the major growth factor is granulocyte-macrophage-colony stimulating factor. Using this selection point model, EML cells exhibit increases in cellular plasticity when they are better able to adapt to this medium and survive. Increases in cellular plasticity were found to occur upon exposure to geldanamycin to inhibit HSP90, when subjected to various forms of cellular stress, or inhibition of histone acetylation. Furthermore, we provide evidence that the cellular plasticity associated with inhibition of HSP90 in this model involves epigenetic mechanisms and is dependent upon high levels of stem cell factor signaling. This work provides evidence for a role of HSP90 and cellular stress in inducing phenotypic plasticity in mammalian systems that has new implications for cellular stress in progression and evolution of cancer.

EurEAs_Gplex--A new SNaPshot assay for continental population discrimination and gender identification.

PubMed

Daca-Roszak, P; Pfeifer, A; Żebracka-Gala, J; Jarząb, B; Witt, M; Ziętkiewicz, E

2016-01-01

Assays that allow analysis of the biogeographic origin of biological samples in a standard forensic laboratory have to target a small number of highly differentiating markers. Such markers should be easy to multiplex and the assay must perform well in the degraded and scarce biological material. SNPs localized in the genome regions, which in the past were subjected to differential selective pressure in various populations, are the most widely used markers in the studies of biogeographic affiliation. SNPs reflecting biogeographic differences not related to any phenotypic traits are not sufficiently explored. The goal of our study was to identify a small set of SNPs not related to any known pigmentation/phenotype-specific genes, which would allow efficient discrimination between populations of Europe and East Asia. The selection of SNPs was based on the comparative analysis of representative European and Chinese/Japanese samples (B-lymphocyte cell lines), genotyped using the Infinium HumanOmniExpressExome microarray (Illumina). The classifier, consisting of 24 unlinked SNPs (24-SNP classifier), was selected. The performance of a 14-SNP subset of this classifier (14-SNP subclassifier) was tested using genotype data from several populations. The 14-SNP subclassifier differentiated East Asians, Europeans and Africans with ∼100% accuracy; Palestinians, representative of the Middle East, clustered with Europeans, while Amerindians and Pakistani were placed between East Asian and European populations. Based on these results, we have developed a SNaPshot assay (EurEAs_Gplex) for genotyping SNPs from the 14-SNP subclassifier, combined with an additional marker for gender identification. Forensic utility of the EurEAs_Gplex was verified using degraded and low quantity DNA samples. The performance of the EurEAs_Gplex was satisfactory when using degraded DNA; tests using low quantity DNA samples revealed a previously not described source of genotyping errors, potentially important for any SNaPshot-based assays. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Summary of results of frictional sliding studies, at confining pressures up to 6.98 kb, in selected rock materials

USGS Publications Warehouse

Summers, R.; Byerlee, J.

1977-01-01

This report is a collection of stress-strain charts which were produced by deforming selected simuiated fault gouge materials. Several sets of samples consisted of intact cylinders, 1.000 inch in diameter and 2.500 inches long. The majority of the samples consisted of thin layers of the selected sample material, inserted within a diagonal sawcut in a 1.000-inch by 2.500-inch Westerly Granite cylinder. Two sorts of inserts were used. The first consisted of thin wafers cut from 1.000-inch-diameter cores of the rock being tested. The other consisted of thin layers of crushed material packed onto the sawcut surface. In several groups of tests using various thicknesses (0.010 inch to 0.160 inch) of a given type material there were variations in the stress level and/or stability of sliding as a function of the fault zone width. Because of this we elected to use a standard 0.025-inch width fault zone to compare the frictional properties of many of the different types of rock materials. This 0.025-inch thickness was chosen partially because this thickness of crushed granite behaves approximately the same as a fractured sample of initially intact granite, and also because this is near the lower limit at which we could cut intact wafers for those samples that were prepared from thin slices of rock. One series of tests was done with saw cut granite cylinders without fault gouge inserts. All of these tests were done in a hydraulically operated triaxial testing machine. The confining pressure (δ1, least principal stress) was applied by pumping petroleum ether into a pressure vessel. The differential stress (δ3-δ1) was applied by a hydraulically operated ram that could be advanced into the pressure vessel at any of several strain rates (10-4sec-1, 10-5sec-1, 10-6sec-1, 10-7sec-1, or 10-8sec-1). All samples were jacketed in polyurethane tubing to exclude the confining pressure medium from the samples. The majority of the samples, with the exception of some of the initially intact rocks, also had thin copper jackets. These served to hold the saw cut parts of the granite sample holders in alignment while the samples were handled and pushed into the polyurethane jackets.

Differential effects of sulindac and indomethacin on blood pressure in treated essential hypertensive subjects.

PubMed

Puddey, I B; Beilin, L J; Vandongen, R; Banks, R; Rouse, I

1985-09-01

Attenuation of the effectiveness of antihypertensive therapy by non-steroidal anti-inflammatory (NSAI) drugs has been attributed to inhibition of systemic or renal vasodilator prostaglandin synthesis, or a combination of both. Indomethacin is a NSAI drug with both renal and extrarenal cyclo-oxygenase inhibition properties. Sulindac is a relatively selective cyclo-oxygenase inhibitor said not to affect urinary prostaglandin excretion. This study examines the relative effect on blood pressure of 4 weeks' treatment, with indomethacin 25 mg three times daily and sulindac 200 mg twice daily, in a randomized placebo controlled trial in 26 hypertensive subjects. In nine patients treated with indomethacin, supine blood pressure rose 11 mmHg systolic and 4 mmHg diastolic by the end of the first week, whereas nine subjects treated with sulindac showed a fall in blood pressure similar to the trend seen in placebo-treated subjects. Indomethacin treatment inhibited renal cyclo-oxygenase with a 78% reduction in urinary prostaglandin E2 excretion and 89% suppression of plasma renin activity. Neither measurement was affected by sulindac. Extrarenal cyclo-oxygenase activity was inhibited by both indomethacin and sulindac with serum thromboxane B2 decreasing by 96% and 69% respectively. The results suggest that the pressor effect of NSAI drugs is predominantly related to renal cyclo-oxygenase inhibition. the lack of effect of sulindac on blood pressure may make it a safer therapeutic option if NSAI drug therapy is necessary in the hypertensive patient.

Oil field management system

DOEpatents

Fincke, James R.

2003-09-23

Oil field management systems and methods for managing operation of one or more wells producing a high void fraction multiphase flow. The system includes a differential pressure flow meter which samples pressure readings at various points of interest throughout the system and uses pressure differentials derived from the pressure readings to determine gas and liquid phase mass flow rates of the high void fraction multiphase flow. One or both of the gas and liquid phase mass flow rates are then compared with predetermined criteria. In the event such mass flow rates satisfy the predetermined criteria, a well control system implements a correlating adjustment action respecting the multiphase flow. In this way, various parameters regarding the high void fraction multiphase flow are used as control inputs to the well control system and thus facilitate management of well operations.

Selective AR Modulators that Distinguish Proliferative from Differentiative Gene Promoters

DTIC Science & Technology

2016-08-01

AWARD NUMBER: W81XWH-14-1-0292 TITLE: Selective AR Modulators that Distinguish Proliferative from Differentiative Gene Promoters PRINCIPAL...Approved for Public Release; Distribution Unlimited The views, opinions and/or findings contained in this report are those of the author(s) and...29 Jul 2016 4. TITLE AND SUBTITLE Selective AR Modulators that Distinguish Proliferative from Differentiative Gene Promoters 5a. CONTRACT NUMBER

An Exploratory Analysis of Differential Program Costs of Selected Occupational Curricula in Selected Illinois Junior Colleges. Final Report.

ERIC Educational Resources Information Center

Tomlinson, Robert M.; Rzonca, Chester S.

This cost differential study was designed to use data collected by the Division of Vocational and Technical Education and the Illinois Junior College Board in an effort to analyze differential program costs of selected occupational curricula in six sample community colleges incurred in the fiscal year 1968-69. To be effective, a cost accounting…

Compensated vibrating optical fiber pressure measuring device

DOEpatents

Fasching, George E.; Goff, David R.

1987-01-01

A microbending optical fiber is attached under tension to a diaphragm to se a differential pressure applied across the diaphragm which it causes it to deflect. The fiber is attached to the diaphragm so that one portion of the fiber, attached to a central portion of the diaphragm, undergoes a change in tension; proportional to the differential pressure applied to the diaphragm while a second portion attached at the periphery of the diaphragm remains at a reference tension. Both portions of the fiber are caused to vibrate at their natural frequencies. Light transmitted through the fiber is attenuated by both portions of the tensioned sections of the fiber by an amount which increases with the curvature of fiber bending so that the light signal is modulated by both portions of the fiber at separate frequencies. The modulated light signal is transduced into a electrical signal. The separate modulation signals are detected to generate separate signals having frequencies corresponding to the reference and measuring vibrating sections of the continuous fiber, respectively. A signal proportional to the difference between these signals is generated which is indicative of the measured pressure differential across the diaphragm. The reference portion of the fiber is used to compensate the pressure signal for zero and span changes resulting from ambient temperature and humidity effects upon the fiber and the transducer fixture.

Comparing effects of perfusion and hydrostatic pressure on gene profiles of human chondrocyte.

PubMed

Zhu, Ge; Mayer-Wagner, Susanne; Schröder, Christian; Woiczinski, Matthias; Blum, Helmut; Lavagi, Ilaria; Krebs, Stefan; Redeker, Julia I; Hölzer, Andreas; Jansson, Volkmar; Betz, Oliver; Müller, Peter E

2015-09-20

Hydrostatic pressure and perfusion have been shown to regulate the chondrogenic potential of articular chondrocytes. In order to compare the effects of hydrostatic pressure plus perfusion (HPP) and perfusion (P) we investigated the complete gene expression profiles of human chondrocytes under HPP and P. A simplified bioreactor was constructed to apply loading (0.1 MPa for 2 h) and perfusion (2 ml) through the same piping by pressurizing the medium directly. High-density monolayer cultures of human chondrocytes were exposed to HPP or P for 4 days. Controls (C) were maintained in static cultures. Gene expression was evaluated by sequencing (RNAseq) and quantitative real-time PCR analysis. Both treatments changed gene expression levels of human chondrocytes significantly. Specifically, HPP and P increased COL2A1 expression and decreased COL1A1 and MMP-13 expression. Despite of these similarities, RNAseq revealed a list of cartilage genes including ACAN, ITGA10 and TNC, which were differentially expressed by HPP and P. Of these candidates, adhesion related molecules were found to be upregulated in HPP. Both HPP and P treatment had beneficial effects on chondrocyte differentiation and decreased catabolic enzyme expression. The study provides new insight into how hydrostatic pressure and perfusion enhance cartilage differentiation and inhibit catabolic effects. Copyright © 2015 Elsevier B.V. All rights reserved.

Elevated hydrostatic pressure triggers release of OPA1 and cytochrome C, and induces apoptotic cell death in differentiated RGC-5 cells

PubMed Central

Kim, Keun-Young; Lindsey, James D.; Angert, Mila; Patel, Ankur; Scott, Ray T.; Liu, Quan; Crowston, Jonathan G.; Ellisman, Mark H.; Perkins, Guy A.; Weinreb, Robert N.

2009-01-01

Purpose This study was conducted to determine whether elevated hydrostatic pressure alters mitochondrial structure, triggers release of the dynamin-related guanosine triphosphatase (GTPase) optic atrophy type 1 (OPA1) or cytochrome C from mitochondria, alters OPA1 gene expression, and can directly induce apoptotic cell death in cultured retinal ganglion cell (RGC)-5 cells. Methods Differentiated RGC-5 cells were exposed to 30 mmHg for three days in a pressurized incubator. As a control, differentiated RGC-5 cell cultures were incubated simultaneously in a conventional incubator. Live RGC-5 cells were then labeled with MitoTracker Red and mitochondrial morphology was assessed by fluorescence microscopy. Mitochondrial structural changes were also assessed by electron microscopy and three-dimenstional (3D) electron microscope tomography. OPA1 mRNA was measured by Taqman quantitative PCR. The cellular distribution of OPA1 protein and cytochrome C was assessed by immunocytochemistry and western blot. Caspase-3 activation was examined by western blot. Apoptotic cell death was evaluated by the terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) method. Results Mitochondrial fission, characterized by the conversion of tubular fused mitochondria into isolated small organelles, was triggered after three days exposure to elevated hydrostatic pressure. Electron microscopy confirmed the fission and noted no changes to mitochondrial architecture, nor outer membrane rupture. Electron microscope tomography showed that elevated pressure depleted mitochondrial cristae content by fourfold. Elevated hydrostatic pressure increased OPA1 gene expression by 35±14% on day 2, but reduced expression by 36±4% on day 3. Total OPA1 protein content was not changed on day 2 or 3. However, pressure treatment induced release of OPA1 and cytochrome C from mitochondria to the cytoplasm. Elevated pressure also activated caspase-3 and induced apoptotic cell death. Conclusions Elevated hydrostatic pressure triggered mitochondrial changes including mitochondrial fission and abnormal cristae depletion, alteration of OPA1 gene expression, and release of OPA1 and cytochrome C into the cytoplasm before the onset of apoptotic cell death in differentiated RGC-5 cells. These results suggest that sustained moderate pressure elevation may directly damage RGC integrity by injuring mitochondria. PMID:19169378

Control of bed height in a fluidized bed gasification system

DOEpatents

Mehta, Gautam I.; Rogers, Lynn M.

1983-12-20

In a fluidized bed apparatus a method for controlling the height of the fdized bed, taking into account variations in the density of the bed. The method comprises taking simultaneous differential pressure measurements at different vertical elevations within the vessel, averaging the differential pressures, determining an average fluidized bed density, then periodically calculating a weighting factor. The weighting factor is used in the determination of the actual bed height which is used in controlling the fluidizing means.

Differential absorption lidars for remote sensing of atmospheric pressure and temperature profiles

NASA Technical Reports Server (NTRS)

Korb, C. Laurence; Schwemmer, Geary K.; Famiglietti, Joseph; Walden, Harvey; Prasad, Coorg

1995-01-01

A near infrared differential absorption lidar technique is developed using atmospheric oxygen as a tracer for high resolution vertical profiles of pressure and temperature with high accuracy. Solid-state tunable lasers and high-resolution spectrum analyzers are developed to carry out ground-based and airborne measurement demonstrations and results of the measurements presented. Numerical error analysis of high-altitude airborne and spaceborne experiments is carried out, and system concepts developed for their implementation.

Differential high pressure survival in stationary-phase Escherichia coli MG1655

NASA Astrophysics Data System (ADS)

Griffin, Patrick L.; Kish, Adrienne; Steele, Andrew; Hemley, Russell J.

2011-06-01

Hydrostatic pressure exerts a profound influence on nearly all facets of cellular structure and function with exposures to sufficiently high pressure leading to microbial inactivation. We report the first observation of a persistent, pressure-resistant subpopulation within stationary-phase samples of Escherichia coli MG1655, a mesophilic bacterium adapted to surface pressure. This high pressure-resistant subpopulation exhibits pressure survival ranging from 0.6 to 2.0 orders of magnitude greater survival than high pressure treatments at pressures of 225-400 MPa. We also examine some aspects of pressure treatment protocol that may influence the measurements of high pressure survival.

A Model for the Oxidation of C/SiC Composite Structures

NASA Technical Reports Server (NTRS)

Sullivan, Roy M.

2003-01-01

A mathematical theory and an accompanying numerical scheme have been developed for predicting the oxidation behavior of C/SiC composite structures. The theory is derived from the mechanics of the flow of ideal gases through a porous solid. Within the mathematical formulation, two diffusion mechanisms are possible: (1) the relative diffusion of one species with respect to the mixture, which is concentration gradient driven and (2) the diffusion associated with the average velocity of the gas mixture, which is total gas pressure gradient driven. The result of the theoretical formulation is a set of two coupled nonlinear differential equations written in terms of the oxidant and oxide partial pressures. The differential equations must be solved simultaneously to obtain the partial vapor pressures of the oxidant and oxides as a function of space and time. The local rate of carbon oxidation is determined as a function of space and time using the map of the local oxidant partial vapor pressure along with the Arrhenius rate equation. The nonlinear differential equations are cast into matrix equations by applying the Bubnov-Galerkin weighted residual method, allowing for the solution of the differential equations numerically. The end result is a numerical scheme capable of determining the variation of the local carbon oxidation rates as a function of space and time for any arbitrary C/SiC composite structures.

Genome-Wide Variation Patterns Uncover the Origin and Selection in Cultivated Ginseng (Panax ginseng Meyer)

PubMed Central

Li, Ming-Rui; Shi, Feng-Xue; Li, Ya-Ling; Jiang, Peng; Jiao, Lili

2017-01-01

Abstract Chinese ginseng (Panax ginseng Meyer) is a medicinally important herb and plays crucial roles in traditional Chinese medicine. Pharmacological analyses identified diverse bioactive components from Chinese ginseng. However, basic biological attributes including domestication and selection of the ginseng plant remain under-investigated. Here, we presented a genome-wide view of the domestication and selection of cultivated ginseng based on the whole genome data. A total of 8,660 protein-coding genes were selected for genome-wide scanning of the 30 wild and cultivated ginseng accessions. In complement, the 45s rDNA, chloroplast and mitochondrial genomes were included to perform phylogenetic and population genetic analyses. The observed spatial genetic structure between northern cultivated ginseng (NCG) and southern cultivated ginseng (SCG) accessions suggested multiple independent origins of cultivated ginseng. Genome-wide scanning further demonstrated that NCG and SCG have undergone distinct selection pressures during the domestication process, with more genes identified in the NCG (97 genes) than in the SCG group (5 genes). Functional analyses revealed that these genes are involved in diverse pathways, including DNA methylation, lignin biosynthesis, and cell differentiation. These findings suggested that the SCG and NCG groups have distinct demographic histories. Candidate genes identified are useful for future molecular breeding of cultivated ginseng. PMID:28922794

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.

Lifetime competing risks between coronary heart disease mortality and other causes of death during 50years of follow-up.

PubMed

Puddu, Paolo Emilio; Piras, Paolo; Menotti, Alessandro

2017-02-01

To study coronary heart disease (CHD) death versus 11 other causes of death using the cumulative incidence function (CIF) and the competing risks procedures to disentangle the differential role of risk factors for different end-points. Standard Cox and Fine-Gray models among 1712 middle-aged men were compared during 50years of follow-up. CHD death was the primary event, while deaths from 11 selected causes, mutually exclusive from the primary end-point, were considered as secondary events. Reverse solutions were also performed. We considered 10 selected risk factors. CHD death risk was the second highest among 12 mostly specific causes of death. Some risk factors were specific: serum cholesterol for CHD death whereas, systolic blood pressure, cigarette smoking and age may have a differential role in other causes of death. Application of the Fine-Gray model based on CIF enabled to dissect, at least in part, the respective role that baseline covariates may have to segregate the probabilities of two types of death in contrast from each other. They also point to the absence of contributing significance for some of the selected risk factors and this calls for a parsimonious approach in predictions. The relative rarity of competing risk challenges when defining the risk factors role at long-term needs now be corrected since we have clearly shown, with Fine-Gray model, at direct or reverse use, that comparing different end-points heavily influences the risk factor predictive capacity. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

The Effects of Core Composition on Iron Isotope Fractionation During Planetary Differentiation

NASA Astrophysics Data System (ADS)

Elardo, S. M.; Shahar, A.; Caracas, R.; Mock, T. D.; Sio, C. K. I.

2018-05-01

High pressure and temperature isotope exchange experiments and density functional theory calculations show how the composition of planetary cores affects the fractionation of iron isotopes during planetary differentiation.

Pulse thermal energy transport/storage system

DOEpatents

Weislogel, Mark M.

1992-07-07

A pulse-thermal pump having a novel fluid flow wherein heat admitted to a closed system raises the pressure in a closed evaporator chamber while another interconnected evaporator chamber remains open. This creates a large pressure differential, and at a predetermined pressure the closed evaporator is opened and the opened evaporator is closed. This difference in pressure initiates fluid flow in the system.

Multiplexing Transducers Based on Tunnel-Diode Oscillators

NASA Technical Reports Server (NTRS)

Chui, Talso; Penanen, Konstantin; Young, Joseph

2006-01-01

Multiplexing and differential transducers based on tunnel-diode oscillators (TDOs) would be developed, according to a proposal, for operation at very low and/or widely varying temperatures in applications that involve requirements to minimize the power and mass of transducer electronic circuitry. It has been known since 1975 that TDOs are useful for making high-resolution (of the order of 10(exp -9)) measurements at low temperatures. Since that time, TDO transducers have been found to offer the following additional advantages, which the present proposal is intended to exploit: TDO transducers can operate at temperatures ranging from 1 K to about 400 K. Most electronic components other than tunnel diodes do not operate over such a wide temperature range. TDO transducers can be made to operate at very low power - typically, <1 mW. Inasmuch as the response of a TDO transducer is a small change in an arbitrarily set oscillation frequency, the outputs of many TDOs operating at sufficiently different set frequencies can be multiplexed through a single wire. Inasmuch as frequencies can be easily subtracted by means of mixing circuitry, one can easily use two TDOs to make differential measurements. Differential measurements are generally more precise and less susceptible to environmental variations than are absolute measurements. TDO transducers are tolerant to ionizing radiation. Ultimately, the response of a TDO transducer is measured by use of a frequency counter. Because frequency counting can be easily implemented by use of clock signals available from most microprocessors, it is not necessary to incorporate additional readout circuitry that would, if included, add to the mass and power consumption of the transducer circuitry. In one example of many potential variations on the basic theme of the proposal, the figure schematically depicts a conceptual differential-pressure transducer containing a symmetrical pair of TDOs. The differential pressure would be exerted on an electrically conductive and grounded diaphragm, which, at zero differential pressure, would nominally be sprung to a middle position between two capacitor plates that would be parts of the two TDOs. The frequencies of the two TDOs would vary in opposite directions as variations in differential pressure bent the diaphragm away from one capacitor plate and toward the other. The outputs of the TDOs would be mixed and lowpass filtered to obtain a signal at the difference between the frequencies of the two TDOs. The difference frequency would be measured by a frequency counter and converted to differential pressure by a computer.

14 CFR 25.841 - Pressurized cabins.

Code of Federal Regulations, 2013 CFR

2013-01-01

... differentials up to the maximum relief valve setting in combination with landing loads. (8) The pressure sensors... located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger... increase the hazards resulting from decompression. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended...

14 CFR 25.841 - Pressurized cabins.

Code of Federal Regulations, 2010 CFR

2010-01-01

... differentials up to the maximum relief valve setting in combination with landing loads. (8) The pressure sensors... located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger... increase the hazards resulting from decompression. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended...

14 CFR 25.841 - Pressurized cabins.

Code of Federal Regulations, 2014 CFR

2014-01-01

... differentials up to the maximum relief valve setting in combination with landing loads. (8) The pressure sensors... located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger... increase the hazards resulting from decompression. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended...

14 CFR 25.841 - Pressurized cabins.

Code of Federal Regulations, 2011 CFR

2011-01-01

... differentials up to the maximum relief valve setting in combination with landing loads. (8) The pressure sensors... located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger... increase the hazards resulting from decompression. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended...

14 CFR 25.841 - Pressurized cabins.

Code of Federal Regulations, 2012 CFR

2012-01-01

... differentials up to the maximum relief valve setting in combination with landing loads. (8) The pressure sensors... located and the sensing system designed so that, in the event of loss of cabin pressure in any passenger... increase the hazards resulting from decompression. [Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended...

49 CFR 178.338-14 - Gauging devices.

Code of Federal Regulations, 2011 CFR

2011-10-01

... gauging devices, which accurately indicate the maximum permitted liquid level at the loading pressure, in... trycock line, or a differential pressure liquid level gauge must be used as the primary control for... filling. (2) The design pressure of each liquid level gauging device must be at least that of the tank. (3...

49 CFR 178.338-14 - Gauging devices.

Code of Federal Regulations, 2014 CFR

2014-10-01

... gauging devices, which accurately indicate the maximum permitted liquid level at the loading pressure, in... trycock line, or a differential pressure liquid level gauge must be used as the primary control for... filling. (2) The design pressure of each liquid level gauging device must be at least that of the tank. (3...

49 CFR 178.338-14 - Gauging devices.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., a fixed trycock line, or a differential pressure liquid level gauge must be used as the primary... control for filling. (2) The design pressure of each liquid level gauging device must be at least that of... openings for dip tube gauging devices and pressure gauges in flammable cryogenic liquid service must be...

49 CFR 178.338-14 - Gauging devices.

Code of Federal Regulations, 2012 CFR

2012-10-01

... gauging devices, which accurately indicate the maximum permitted liquid level at the loading pressure, in... trycock line, or a differential pressure liquid level gauge must be used as the primary control for... filling. (2) The design pressure of each liquid level gauging device must be at least that of the tank. (3...

49 CFR 178.338-14 - Gauging devices.

Code of Federal Regulations, 2013 CFR

2013-10-01

... gauging devices, which accurately indicate the maximum permitted liquid level at the loading pressure, in... trycock line, or a differential pressure liquid level gauge must be used as the primary control for... filling. (2) The design pressure of each liquid level gauging device must be at least that of the tank. (3...

Saturation meter

DOEpatents

Gregurech, S.

1984-08-01

A saturation meter for use in a pressurized water reactor plant comprising a differential pressure transducer having a first and second pressure sensing means and an alarm. The alarm is connected to the transducer and is preset to activate at a level of saturation prior to the formation of a steam void in the reactor vessel.

49 CFR 232.103 - General requirements for all train brake systems.

Code of Federal Regulations, 2013 CFR

2013-10-01

... the air compressor governor starting or loading pressure. (l) Except as otherwise provided in this... brake pipe air pressure: Road Service 90 Switch Service 60 (2) Minimum differential between brake pipe and main reservoir air pressures, with brake valve in running position 15 (3) Safety valve for...

49 CFR 232.103 - General requirements for all train brake systems.

Code of Federal Regulations, 2012 CFR

2012-10-01

... the air compressor governor starting or loading pressure. (l) Except as otherwise provided in this... brake pipe air pressure: Road Service 90 Switch Service 60 (2) Minimum differential between brake pipe and main reservoir air pressures, with brake valve in running position 15 (3) Safety valve for...

Chondrocyte response to cyclic hydrostatic pressure in alginate versus pellet culture.

PubMed

Elder, Steven H; Sanders, Shawn W; McCulley, William R; Marr, Misti L; Shim, Joon W; Hasty, Karen A

2006-04-01

Cells are often cultured at high density (e.g., confluent monolayer and as pellets) to promote chondrogenic differentiation and to maintain the chondrocyte phenotype. They are also frequently suspended in hydrogels such as agarose or alginate for the same purposes. These culture techniques differ markedly with respect to frequency of direct contact between cells and overall intercellular spacing. Because these factors may significantly affect mechanotransduction, the purpose of this study was to determine if the response of articular chondrocytes to cyclic hydrostatic pressure would depend on the culture condition. Primary articular chondrocytes from young and mature pigs were cultured either as pellets or suspended in alginate beads. Both groups were exposed to dynamic hydrostatic pressure (4 MPa, 1 Hz, 5400 cycles per day) for 7 days. Cell proliferation was unaffected by pressure, but pressurized chondrocytes in pellet culture had significantly greater sGAG content and incorporated [3H]proline at a higher rate than nonpressurized controls. Electron microscopy revealed a fibrous extracellular matrix (ECM) surrounding pellets, but not cells in alginate. In addition, expression of Connexin 43 (Cx43) mRNA was slightly lower in alginate than in pellet cultures and was not significantly altered by loading. Thus, metabolic response of chondrocytes to dynamic hydrostatic pressure was affected by culture technique; chondrocytes cultured as pellets exhibited the classical anabolic response to dynamic hydrostatic pressure, but those in alginate did not. Although cell-ECM interaction could be important, the differential response is not likely attributable to differential expression of Cx43 mRNA. Copyright 2006 Orthopaedic Research Society

Recovering Aerodynamic Side Loads on Rocket Nozzles using Quasi-Static Strain-Gage Measurements

NASA Technical Reports Server (NTRS)

Brown, Andrew; Ruf, Joseph H.; McDaniels, David M.

2009-01-01

During over-expanded operation of rocket nozzles, which is defined to be when the exit pressure is greater than internal pressure over some part of the nozzle, the nozzle will experience a transverse forcing function due to the pressure differential across the nozzle wall. Over-expansion occurs during the nozzle start-up and shutdown transient, even in high-altitude engines, because most test facilities cannot completely reproduce the near-vacuum pressures at those altitudes. During this transient, the pressure differential moves axially down the nozzle as it becomes pressurized, but this differential is never perfectly symmetric circumferentially. The character of the forcing function is highly complex and defined by a series of restricted and free shock separations. The subject of this paper is the determination of the magnitude of this loading during sub-scale testing via measurement of the structural dynamic response of the nozzle and its support structure. An initial attempt at back-calculating this load using the inverse of the transfer function was performed, but this attempt was shown to be highly susceptible to numerical error. The final method chosen was to use statically calibrated strain data and to filter out the system fundamental frequency such that the measured response yields close to the correct dynamic loading function. This method was shown to capture 93% of the pressure spectral energy using controlled load shaker testing. This method is one of the only practical ways for the inverse determination of the forcing function for non-stationary excitations, and, to the authors' knowledge, has not been described in the literature to date.

Mobility of an elastic glove for extravehicular activity without prebreathing.

PubMed

Tanaka, Kunihiko; Ikeda, Mizuki; Mochizuki, Yosuke; Katafuchi, Tetsuro

2011-09-01

The current U.S. extravehicular activity (EVA) suit is pressurized at 0.29 atm, which is much lower than the pressures of sea level and inside a space station. Higher pressure can reduce the risk of decompression sickness (DCS), but mobility would be sacrificed. We have demonstrated that a glove and sleeve made of elastic material increased mobility when compared with those made of nonelastic material, such as that found in the current suit. We hypothesized that an elastic glove of 0.65 atm that has no risk of DCS also has greater mobility compared with a non-elastic glove of 0.29 atm. The right hands of 10 healthy volunteers were studied in a chamber with their bare hands at normal ambient pressure, after donning a non-elastic glove with a pressure differential of 0.29 atm, and after donning an elastic glove with a pressure differential of 0.29 and 0.65 atm. Range of motion (ROM) of the index finger and surface electromyography (EMG) amplitudes during finger flexion were measured. ROM with gloves was significantly smaller than that of bare hands, but was similar between conditions of gloves regardless of elasticity and pressure differentials. However, EMG amplitudes with the elastic glove of 0.29 and 0.65 atm were significantly smaller than those with the non-elastic glove of 0.29 atm. The results suggest that mobility of the elastic glove of 0.65 atm may be better than that of the non-elastic glove of 0.29 atm, similar to that used in the current EVA suit.

Effect of ambient pressure variation on closed loop gas system for India based Neutrino Observatory (INO)

NASA Astrophysics Data System (ADS)

Satyanarayana, B.; Majumder, G.; Mondal, N. K.; Kalmani, S. D.; Shinde, R. R.; Joshi, A.

2014-10-01

Pilot unit of a closed loop gas mixing and distribution system for the INO project was designed and is being operated with 1.8meters × 1.9meters RPCs for about two years. A number of studies on controlling the flow and optimisation of the gas mixture through the RPC stack were carried out during this period. The gas system essentially measures and attempts to maintain absolute pressure inside the RPC gas volume. During typical Mumbai monsoon seasons, the barometric pressure changes rather rapidly, due to which the gas system fails to maintain the set differential pressure between the ambience and the RPC gas volume. As the safety bubblers on the RPC gas input lines are set to work on fixed pressure differentials, the ambient pressure changes lead to either venting out and thus wasting gas through safety bubblers or over pressuring the RPCs gas volume and thus degrading its performance. The above problem also leads to gas mixture contamination through minute leaks in gas gap. The problem stated above was solved by including the ambient barometric pressure as an input parameter in the closed loop. Using this, it is now possible to maintain any set differential pressure between the ambience and RPC gas volumes between 0 to 20mm of water column, thus always ensuring a positive pressure inside the RPC gas volume with respect to the ambience. This has resulted in improved performance of the gas system by maintaining the constant gas flow and reducing the gas toping up frequency. In this paper, we will highlight the design features and improvements of the closed loop gas system. We will present some of the performance studies and considerations for scaling up the system to be used with the engineering module and then followed by Iron Calorimeter detector (ICAL), which is designed to deploy about 30,000 RPCs of 1.8meters × 1.9 meters in area.

ULF/VLF (0.001 to 50 Hz) Seismo-Acoustic Noise in the Ocean. Proceedings of a Workshop Held at Austin, Texas on November 29-December 1, 1988

DTIC Science & Technology

1989-08-03

holes drilled in the seafloor from the D/V JOIDES Resolution through petrological , geochemical and paleomagnetic studies of the samples and logging...seismome- ters and/or hydrophones (or differential pressure gauges , DPG). Testing of the new instruments at very early stages is important to ensure...resolved using ocean bottom seismometers, suspended hydrophones and differential pressure gauges assisted by an orbiting radar altimeter (GEOSAT

Restrike Particle Beam Experiments on a Dense Plasma Focus.

DTIC Science & Technology

1980-11-30

differentially pumped drift tube as shown in Figure 1. However, even the lOI of gas pressure in the drift space is sufficient to establish an equilibrium...pumped drift tube concept are five-fold: 1) Lower energy attenuation of the beam by neutral gas 2) Lower lateral spread of the beam caused by multiple...relatively low gas pressure through the use of a differentially pumped drift tube . The path makes it possible to observe ion energies to considerably lower

Control of differential strain during heating and cooling of mixed conducting metal oxide membranes

DOEpatents

Carolan, Michael Francis

2007-12-25

Method of operating an oxygen-permeable mixed conducting membrane having an oxidant feed side and a permeate side, which method comprises controlling the differential strain between the oxidant feed side and the permeate side by varying either or both of the oxygen partial pressure and the total gas pressure on either or both of the oxidant feed side and the permeate side of the membrane while changing the temperature of the membrane from a first temperature to a second temperature.

Colonisation and Diversification of the Zenaida Dove (Zenaida aurita) in the Antilles: Phylogeography, Contemporary Gene Flow and Morphological Divergence

PubMed Central

Monceau, Karine; Cézilly, Frank; Moreau, Jérôme; Motreuil, Sébastien; Wattier, Rémi

2013-01-01

Caribbean avifaunal biogeography has been mainly studied based on mitochondrial DNA. Here, we investigated both past and recent island differentiation and micro-evolutionary changes in the Zenaida Dove (Zenaida aurita) based on combined information from one mitochondrial (Cytochrome c Oxydase subunit I, COI) and 13 microsatellite markers and four morphological characters. This Caribbean endemic and abundant species has a large distribution, and two subspecies are supposed to occur: Z. a. zenaida in the Greater Antilles (GA) and Z. a. aurita in the Lesser Antilles (LA). Doves were sampled on two GA islands (Puerto Rico and the British Virgin Islands) and six LA islands (Saint Barthélemy, Guadeloupe, Les Saintes, Martinique, Saint Lucia and Barbados). Eleven COI haplotypes were observed that could be assembled in two distinct lineages, with six specific to GA, four to LA, the remaining one occurring in all islands. However, the level of divergence between those two lineages was too moderate to fully corroborate the existence of two subspecies. Colonisation of the studied islands appeared to be a recent process. However, both phenotypic and microsatellite data suggest that differentiation is already under way between all of them, partly associated with the existence of limited gene flow. No isolation by distance was observed. Differentiation for morphological traits was more pronounced than for neutral markers. These results suggest that despite recent colonisation, genetic drift and/or restricted gene flow are promoting differentiation for neutral markers. Variation in selective pressures between islands may explain the observed phenotypic differentiation. PMID:24349217

The Streaming Potential Generated by Flow of Wet Steam in Capillary Tubes

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

Marsden, S.S. Jr.; Tyran, Craig K.

1986-01-21

For a constant pressure differential, the flow of wet steam generated electric potentials which increased with time and did not reach equilibrium values. These potentials were found to increase to values greater than 100 volts. The reason for this kind of potential build-up behavior was the presence of tiny flowing water slugs which were interspersed with electrically nonconductive steam vapor slugs. The measured electric potential for wet steam increased with pressure differential, but the relationship was not linear. The increase in potential with pressure drop was attributed both to an increase in fluid flow rate and changes in the wetmore » steam quality.« less

Flowrate testing of the bag filter LANCS-BOP 6CPVC-1.5-2SPVC (LANCS Industries) at 1 psig

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

Moore, Murray E.; Currie, Karissa Lyn; Berg, Charlotte Katherine

2016-09-13

The air flowrate through a flexible HEPA grade filter (Part LANCS-BOP 6CPVC-1.5-2SPVC www.lancsindustries.com) was measured at 48 ALPM for a differential pressure drop of 1.0 psig (28 inWC, 7.0 kPa). These filters are rated by the manufacturer to have a flowrate of 3 ALPM at a differential pressure drop of 1 inWC (0.25 kPa). The Los Alamos National Laboratory Aerosol Engineering Facility used one of their test rigs (originally developed to measure the pressure drop in capsule HEPA filters) to measure the airflow through the LANCS bag filter.

Rugged switch responds to minute pressure differentials

NASA Technical Reports Server (NTRS)

Friend, L. C.; Shaub, K. D.

1967-01-01

Pressure responsive switching device exhibits high sensitivity but is extremely rugged and resistant to large amplitude shock and velocity loading. This snap-action, single pole-double throw switch operates over a wide temperature range.

Common pressure vessel battery performance

NASA Technical Reports Server (NTRS)

Otzinger, B.

1978-01-01

Performance tests run on two common pressure vessel type nickel hydrogen batteries are described and the results presented. The study included: (1) charge retention tests, (2) synchronous eclipse season cycling tests, and (3) temperature differential tests.

Limited Evidence for Classic Selective Sweeps in African Populations

PubMed Central

Granka, Julie M.; Henn, Brenna M.; Gignoux, Christopher R.; Kidd, Jeffrey M.; Bustamante, Carlos D.; Feldman, Marcus W.

2012-01-01

While hundreds of loci have been identified as reflecting strong-positive selection in human populations, connections between candidate loci and specific selective pressures often remain obscure. This study investigates broader patterns of selection in African populations, which are underrepresented despite their potential to offer key insights into human adaptation. We scan for hard selective sweeps using several haplotype and allele-frequency statistics with a data set of nearly 500,000 genome-wide single-nucleotide polymorphisms in 12 highly diverged African populations that span a range of environments and subsistence strategies. We find that positive selection does not appear to be a strong determinant of allele-frequency differentiation among these African populations. Haplotype statistics do identify putatively selected regions that are shared across African populations. However, as assessed by extensive simulations, patterns of haplotype sharing between African populations follow neutral expectations and suggest that tails of the empirical distributions contain false-positive signals. After highlighting several genomic regions where positive selection can be inferred with higher confidence, we use a novel method to identify biological functions enriched among populations’ empirical tail genomic windows, such as immune response in agricultural groups. In general, however, it seems that current methods for selection scans are poorly suited to populations that, like the African populations in this study, are affected by ascertainment bias and have low levels of linkage disequilibrium, possibly old selective sweeps, and potentially reduced phasing accuracy. Additionally, population history can confound the interpretation of selection statistics, suggesting that greater care is needed in attributing broad genetic patterns to human adaptation. PMID:22960214

Ultra-thin nanocrystalline diamond membranes as pressure sensors for harsh environments

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

Janssens, S. D., E-mail: stoffel.d.janssens@gmail.com; Haenen, K., E-mail: ken.haenen@uhasselt.be; IMOMEC, IMEC vzw, Wetenschapspark 1, B-3590 Diepenbeek

2014-02-17

Glass and diamond are suitable materials for harsh environments. Here, a procedure for fabricating ultra-thin nanocrystalline diamond membranes on glass, acting as an electrically insulating substrate, is presented. In order to investigate the pressure sensing properties of such membranes, a circular, highly conductive boron-doped nanocrystalline diamond membrane with a resistivity of 38 mΩ cm, a thickness of 150 nm, and a diameter of 555 μm is fabricated in the middle of a Hall bar structure. During the application of a positive differential pressure under the membrane (0–0.7 bar), four point piezoresistive effect measurements are performed. From these measurements, it can be concluded that the resistancemore » response of the membrane, as a function of differential pressure, is highly linear and sensitive.« less

Enhancing cuttings removal with gas blasts while drilling on Mars

NASA Astrophysics Data System (ADS)

Zacny, K. A.; Quayle, M. C.; Cooper, G. A.

2005-04-01

Future missions to Mars envision use of drills for subsurface exploration. Since the Martian atmosphere precludes the use of liquids for cuttings removal, proposed drilling machines utilize mechanical cuttings removal systems such as augers. However, an auger can substantially contribute to the total power requirements, and in the worst scenario it can choke. A number of experiments conducted under Martian pressures showed that intermittent blasts of gas at low differential pressures can effectively lift the cuttings out of the hole. A gas flushing system could be incorporated into the drill assembly for assistance in clearing the holes of rock cuttings or for redundancy in case of auger jamming. A number of variables such as the particle size distribution of the rock powder, the type of gas used, the bit and auger side clearances, the initial mass of cuttings, and the ambient pressure were investigated and found to affect the efficiency. In all tests the initial volume of gas was close to 1 L and the differential pressure was varied to achieve desired clearing efficiencies. Particles were being lifted out of the hole at a maximum speed of 6 m/s at a differential pressure of 25 torr and ambient pressure of 5 torr. Flushing tests lasted on average for 2 s. The power required to compress the thin Martian atmosphere to achieve a sufficient gas blast every minute or so at 10% efficiency was calculated to be of the order of a few watts.

Genes under weaker stabilizing selection increase network evolvability and rapid regulatory adaptation to an environmental shift.

PubMed

Laarits, T; Bordalo, P; Lemos, B

2016-08-01

Regulatory networks play a central role in the modulation of gene expression, the control of cellular differentiation, and the emergence of complex phenotypes. Regulatory networks could constrain or facilitate evolutionary adaptation in gene expression levels. Here, we model the adaptation of regulatory networks and gene expression levels to a shift in the environment that alters the optimal expression level of a single gene. Our analyses show signatures of natural selection on regulatory networks that both constrain and facilitate rapid evolution of gene expression level towards new optima. The analyses are interpreted from the standpoint of neutral expectations and illustrate the challenge to making inferences about network adaptation. Furthermore, we examine the consequence of variable stabilizing selection across genes on the strength and direction of interactions in regulatory networks and in their subsequent adaptation. We observe that directional selection on a highly constrained gene previously under strong stabilizing selection was more efficient when the gene was embedded within a network of partners under relaxed stabilizing selection pressure. The observation leads to the expectation that evolutionarily resilient regulatory networks will contain optimal ratios of genes whose expression is under weak and strong stabilizing selection. Altogether, our results suggest that the variable strengths of stabilizing selection across genes within regulatory networks might itself contribute to the long-term adaptation of complex phenotypes. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

Development of an electrospray-(63)Ni-differential ion mobility spectrometer for the analysis of aqueous samples.

PubMed

Kuklya, Andriy; Uteschil, Florian; Kerpen, Klaus; Marks, Robert; Telgheder, Ursula

2014-03-01

The feasibility of an electrospray coupled with a (63)Ni-differential ion mobility spectrometer (DMS) for the analysis of water samples was proven on examples of 2-hexanone, fluoroacetamide, l-nicotine and 1-phenyl-2-thiourea water solutions. The model substances were selected in order to cover the vapor pressure range of 0.3-1467 Pa. To reduce the inline humidity, which demonstrates a strong influence on the analyte compensation voltage, two units with a desolvation region lengths of 15.5 and 7 mm were examined. The counter gas (heated to 100 °C nitrogen) with flow rates of 100 mL min(-1) and 30 mL min(-1) for short and long desolvation units, respectively, was essential for the efficient reduction of humidity. The reduction of water content in the carrier gas to 2.2-2.4 g m(-3) and to 1.8-2.0 g m(-3) for the short and long desolvation unit, respectively, was achieved at an electrospray flow rate of 1000 nL min(-1). With this adjusted experimental setup, the detection of model substances in the water solutions, in the range of 0.1-50 mg L(-1), was performed. No correlation between the vapor pressure and signal area was observed. The high stability of the inline humidity, and the correspondingly stable carrier gas flow rate, were found to be essential for an acceptable reproducibility. © 2013 Elsevier B.V. All rights reserved.

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.

An Investigation Into Low Fuel Pressure Warnings on a Macchi-Viper Aircraft

DTIC Science & Technology

1988-05-01

was sufficient To activate the low pressure warning light. The pressure switch is normally set to a differential of between 2.5 - 3 psi. Partial...only a 2.1 psig margin for light illumination, if the pressure switch is set at 3 psig, and gives little scope for extra pipe or filter losses when... pressure switch is set between 2.5 - 3 psig. Any untoward pressure resistance in the fuel delivery line and filtering system would soon erode this

Relevance of the Sea Sand Disruption Method (SSDM) for the biometrical differentiation of the essential-oil composition from conifers.

PubMed

Dawidowicz, Andrzej L; Czapczyńska, Natalia B; Wianowska, Dorota

2013-02-01

Sea Sand Disruption Method (SSDM) is a simple and cheap sample-preparation procedure allowing the reduction of organic solvent consumption, exclusion of sample component degradation, improvement of extraction efficiency and selectivity, and elimination of additional sample clean-up and pre-concentration step before chromatographic analysis. This article deals with the possibility of SSDM application for the differentiation of essential-oils components occurring in the Scots pine (Pinus sylvestris L.) and cypress (Cupressus sempervirens L.) needles from Madrid (Spain), Laganas (Zakhyntos, Greece), Cala Morell (Menorca, Spain), Lublin (Poland), Helsinki (Finland), and Oradea (Romania). The SSDM results are related to the analogous - obtained applying two other sample preparation methods - steam distillation and Pressurized Liquid Extraction (PLE). The results presented established that the total amount and the composition of essential-oil components revealed by SSDM are equivalent or higher than those obtained by one of the most effective extraction technique, PLE. Moreover, SSDM seems to provide the most representative profile of all essential-oil components as no heat is applied. Thus, this environmentally friendly method is suggested to be used as the main extraction procedure for the differentiation of essential-oil components in conifers for scientific and industrial purposes. Copyright © 2013 Verlag Helvetica Chimica Acta AG, Zürich.

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra)

PubMed Central

Velo-Antón, G; Zamudio, K R; Cordero-Rivera, A

2012-01-01

Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (FST range: 0.06–0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts. PMID:22086081

Genetic drift and rapid evolution of viviparity in insular fire salamanders (Salamandra salamandra).

PubMed

Velo-Antón, G; Zamudio, K R; Cordero-Rivera, A

2012-04-01

Continental islands offer an excellent opportunity to investigate adaptive processes and to time microevolutionary changes that precede macroevolutionary events. We performed a population genetic study of the fire salamander (Salamandra salamandra), a species that displays unique intraspecific diversity of reproductive strategies, to address the microevolutionary processes leading to phenotypic and genetic differentiation of island, coastal and interior populations. We used eight microsatellite markers to estimate genetic diversity, population structure and demographic parameters in viviparous insular populations and ovoviviparous coastal and interior populations. Our results show considerable genetic differentiation (F(ST) range: 0.06-0.27), and no clear signs of gene flow among populations, except between the large and admixed interior populations. We find no support for island colonization by rafting or intentional/accidental anthropogenic introductions, indicating that rising sea levels were responsible for isolation of the island populations approximately 9000 years ago. Our study provides evidence of rapid genetic differentiation between island and coastal populations, and rapid evolution of viviparity driven by climatic selective pressures on island populations, geographic isolation with genetic drift, or a combination of these factors. Studies of these viviparous island populations in early stages of divergence help us better understand the microevolutionary processes involved in rapid phenotypic shifts.

Cancer Modeling: From Optimal Cell Renewal to Immunotherapy

NASA Astrophysics Data System (ADS)

Alvarado Alvarado, Cesar Leonardo

Cancer is a disease caused by mutations in normal cells. According to the National Cancer Institute, in 2016, an estimated 1.6 million people were diagnosed and approximately 0.5 million people died from the disease in the United States. There are many factors that shape cancer at the cellular and organismal level, including genetic, immunological, and environmental components. In this thesis, we show how mathematical modeling can be used to provide insight into some of the key mechanisms underlying cancer dynamics. First, we use mathematical modeling to investigate optimal homeostatic cell renewal in tissues such as the small intestine with an emphasis on division patterns and tissue architecture. We find that the division patterns that delay the accumulation of mutations are strictly associated with the population sizes of the tissue. In particular, patterns with long chains of differentiation delay the time to observe a second-hit mutant, which is important given that for many cancers two mutations are enough to initiate a tumor. We also investigated homeostatic cell renewal under a selective pressure and find that hierarchically organized tissues act as suppressors of selection; we find that an architecture with a small number of stem cells and larger pools of transit amplifying cells and mature differentiated cells, together with long chains of differentiation, form a robust evolutionary strategy to delay the time to observe a second-hit mutant when mutations acquire a fitness advantage or disadvantage. We also formulate a model of the immune response to cancer in the presence of costimulatory and inhibitory signals. We demonstrate that the coordination of such signals is crucial to initiate an effective immune response, and while immunotherapy has become a promising cancer treatment over the past decade, these results offer some explanations for why it can fail.

Ex-situ gas diffusion layer intrusion effect determination of polymer electrolyte membrane fuel cell flow fields

NASA Astrophysics Data System (ADS)

Haase, S.; Rauber, M.

2015-09-01

In automotive PEM fuel cell systems, one of the most important targets is to reduce the parasitic power of balance of plant components, e.g. the air supply. This can be achieved for example by decreasing air stoichiometry. However, this could lead to bad flow sharing in the fuel cell stack. Therefore the fluid distribution in the flow field has to be evaluated, understood and optimized. This work evaluates the effect of GDL intrusion on the pressure drop via ex-situ determination of GDL intrusion using CFD simulation. The intruded GDL geometries, evaluated by an optical microscope with 200 times enlargement, are transferred to pressure drop behaviors by a numerical CFD model. These results are compared to the results of the differential pressure method of mapping the pressure distribution, described in [43]. The intrusion of the GDL leads to homogeneous flow distribution up to clamping pressures of 2.5 MPa. The inhomogeneous intrusion, induced by cracked fibers that extend into the channel, dominates the flow at higher clamping pressures and leads to the exponential increase in pressure drop in the differential pressure method. For clamping pressures used in typical fuel cell applications, the results of both methods show homogeneous flow through the channels.

Lattice strain of osmium diboride under high pressure and nonhydrostatic stress

NASA Astrophysics Data System (ADS)

Kavner, Abby; Weinberger, Michelle B.; Shahar, Anat; Cumberland, Robert W.; Levine, Jonathan B.; Kaner, Richard B.; Tolbert, Sarah H.

2012-07-01

The lattice strain behavior of osmium diboride—a member of a group of third-row transition metal borides associated with hard/superhard behavior—has been studied using radial diffraction in a diamond anvil cell under high pressure and non-hydrostatic stress. We interpret the average values of the measured lattice strains as a lower-bound to the lattice-plane dependent yield strengths using existing estimates for the elastic constants of OsB2, with a yield strength of 11 GPa at 27.5 GPa of hydrostatic pressure. The measured differential lattice strains show significant plane-dependent anisotropy, with the (101) lattice plane showing the largest differential strain and the (001) lattice plane showing the least strain. At the highest pressure, the a-axis develops a larger compressive strain and supports a larger differential strain than either the b or c axes. This causes an increase in the c/a ratio and a decrease in the a/b ratio especially in the maximum stress direction. The large strength anisotropy of this material points to possible ways to modulate directional mechanical properties by taking advantage of the interplay between aggregate polycrystalline texture with directional mechanical properties.

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

Liu, Xiaobing; Zheng, O'Neill; Niu, Fuxin

Most commercial ground source heat pump systems (GSHP) in the United States are in a distributed configuration. These systems circulate water or an anti-freeze solution through multiple heat pump units via a central pumping system, which usually uses variable speed pump(s). Variable speed pumps have potential to significantly reduce pumping energy use; however, the energy savings in reality could be far away from its potential due to improper pumping system design and controls. In this paper, a simplified hydronic pumping system was simulated with the dynamic Modelica models to evaluate three different pumping control strategies. This includes two conventional controlmore » strategies, which are to maintain a constant differential pressure across either the supply and return mains, or at the most hydraulically remote heat pump; and an innovative control strategy, which adjusts system flow rate based on the demand of each heat pump. The simulation results indicate that a significant overflow occurs at part load conditions when the variable speed pump is controlled to main a constant differential pressure across the supply and return mains of the piping system. On the other hand, an underflow occurs at part load conditions when the variable speed pump is controlled to maintain a constant differential pressure across the furthest heat pump. The flow-demand-based control can provide needed flow rate to each heat pump at any given time, and with less pumping energy use than the two conventional controls. Finally, a typical distributed GSHP system was studied to evaluate the energy saving potential of applying the flow-demand-based pumping control strategy. This case study shows that the annual pumping energy consumption can be reduced by 62% using the flow-demand-based control compared with that using the conventional pressure-based control to maintain a constant differential pressure a cross the supply and return mains.« less

Prevalence of disruptive selection predicts extent of species differentiation in Lake Victoria cichlids.

PubMed

van Rijssel, Jacco C; Moser, Florian N; Frei, David; Seehausen, Ole

2018-01-31

Theory suggests that speciation with gene flow is most likely when both sexual and ecological selection are divergent or disruptive. Divergent sexual and natural selection on the visual system have been demonstrated before in sympatric, morphologically similar sister species of Lake Victoria cichlids, but this does not explain the subtle morphological differences between them. To investigate the significance of natural selection on morphology during speciation, we here ask whether the prevalence of disruptive ecological selection differs between sympatric sister species that are at different stages of speciation. Some of our species pairs do ( Pundamilia ) and others do not ( Neochromis ) differ distinctively in sexually selected male nuptial coloration. We find that (i) evidence for disruptive selection, and for evolutionary response to it, is prevalent in traits that are differentiated between sister species; (ii) prevalence of both predicts the extent of genetic differentiation; and (iii) genetic differentiation is weaker in species pairs with conserved male nuptial coloration. Our results speak to the existence of two different mechanisms of speciation with gene flow: speciation mainly by sexual selection tightly followed by ecological character displacement in some cases and speciation mainly by divergent ecological selection in others. © 2018 The Author(s).

Direct Structural Identification of Gas Induced Gate-Opening Coupled with Commensurate Adsorption in a Microporous Metal-Organic Framework.

PubMed

Banerjee, Debasis; Wang, Hao; Plonka, Anna M; Emge, Thomas J; Parise, John B; Li, Jing

2016-08-08

Gate-opening is a unique and interesting phenomenon commonly observed in flexible porous frameworks, where the pore characteristics and/or crystal structures change in response to external stimuli such as adding or removing guest molecules. For gate-opening that is induced by gas adsorption, the pore-opening pressure often varies for different adsorbate molecules and, thus, can be applied to selectively separate a gas mixture. The detailed understanding of this phenomenon is of fundamental importance to the design of industrially applicable gas-selective sorbents, which remains under investigated due to the lack of direct structural evidence for such systems. We report a mechanistic study of gas-induced gate-opening process of a microporous metal-organic framework, [Mn(ina)2 ] (ina=isonicotinate) associated with commensurate adsorption, by a combination of several analytical techniques including single crystal X-ray diffraction, in situ powder X-ray diffraction coupled with differential scanning calorimetry (XRD-DSC), and gas adsorption-desorption methods. Our study reveals that the pronounced and reversible gate opening/closing phenomena observed in [Mn(ina)2 ] are coupled with a structural transition that involves rotation of the organic linker molecules as a result of interaction of the framework with adsorbed gas molecules including carbon dioxide and propane. The onset pressure to open the gate correlates with the extent of such interaction. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Is isolation by adaptation driving genetic divergence among proximate Dolly Varden char populations?

PubMed Central

Bond, Morgan H; Crane, Penelope A; Larson, Wesley A; Quinn, Tom P

2014-01-01

Numerous studies of population genetics in salmonids and other anadromous fishes have revealed that population structure is generally organized into geographic hierarchies (isolation by distance), but significant structure can exist in proximate populations due to varying selective pressures (isolation by adaptation). In Chignik Lakes, Alaska, anadromous Dolly Varden char (Salvelinus malma) spawn in nearly all accessible streams throughout the watershed, including those draining directly to an estuary, Chignik Lagoon, into larger rivers, and into lakes. Collections of Dolly Varden fry from 13 streams throughout the system revealed low levels of population structure among streams emptying into freshwater. However, much stronger genetic differentiation was detected between streams emptying into freshwater and streams flowing directly into estuarine environments. This fine-scale reproductive isolation without any physical barriers to migration is likely driven by differences in selection pressures across freshwater and estuarine environments. Estuary tributaries had fewer larger, older juveniles, suggesting an alternative life history of smolting and migration to the marine environment at a much smaller size than occurs in the other populations. Therefore, genetic data were consistent with a scenario where isolation by adaptation occurs between populations of Dolly Varden in the study system, and ecological data suggest that this isolation may partially be a result of a novel Dolly Varden life history of seawater tolerance at a smaller size than previously recognized. PMID:25360283

Differences in Blood Pressure and Vascular Responses Associated with Ambient Fine Particulate Matter Exposures Measured at the Personal Versus Community Level

EPA Science Inventory

Background Higher ambient fine particulate matter (PM_2.5) levels can be associated with increased blood pressure and vascular dysfunction. Objectives To determine the differential effects on blood pressure and vascular function of daily changes in community ambient-...

Deciphering the adaptation strategies of Desulfovibrio piezophilus to hydrostatic pressure through metabolic and transcriptional analyses.

PubMed

Amrani, Amira; van Helden, Jacques; Bergon, Aurélie; Aouane, Aicha; Ben Hania, Wajdi; Tamburini, Christian; Loriod, Béatrice; Imbert, Jean; Ollivier, Bernard; Pradel, Nathalie; Dolla, Alain

2016-08-01

Desulfovibrio piezophilus strain C1TLV30(T) is a mesophilic piezophilic sulfate-reducer isolated from Wood Falls at 1700 m depth in the Mediterranean Sea. In this study, we analysed the effect of the hydrostatic pressure on this deep-sea living bacterium at the physiologic and transcriptomic levels. Our results showed that lactate oxidation and energy metabolism were affected by the hydrostatic pressure. Especially, acetyl-CoA oxidation pathway and energy conservation through hydrogen and formate recycling would be more important when the hydrostatic pressure is above (26 MPa) than below (0.1 MPa) the optimal one (10 MPa). This work underlines also the role of the amino acid glutamate as a piezolyte for the Desulfovibrio genus. The transcriptomic analysis revealed 146 differentially expressed genes emphasizing energy production and conversion, amino acid transport and metabolism and cell motility and signal transduction mechanisms as hydrostatic pressure responding processes. This dataset allowed us to identify a sequence motif upstream of a subset of differentially expressed genes as putative pressure-dependent regulatory element. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Betterment, undermining, support and distortion: A heuristic model for the analysis of pressure on evaluators.

PubMed

Pleger, Lyn; Sager, Fritz

2016-09-18

Evaluations can only serve as a neutral evidence base for policy decision-making as long as they have not been altered along non-scientific criteria. Studies show that evaluators are repeatedly put under pressure to deliver results in line with given expectations. The study of pressure and influence to misrepresent findings is hence an important research strand for the development of evaluation praxis. A conceptual challenge in the area of evaluation ethics research is the fact that pressure can be not only negative, but also positive. We develop a heuristic model of influence on evaluations that does justice to this ambivalence of influence: the BUSD-model (betterment, undermining, support, distortion). The model is based on the distinction of two dimensions, namely 'explicitness of pressure' and 'direction of influence'. We demonstrate how the model can be applied to understand pressure and offer a practical tool to distinguish positive from negative influence in the form of three so-called differentiators (awareness, accordance, intention). The differentiators comprise a practical component by assisting evaluators who are confronted with influence. Copyright © 2016 Elsevier Ltd. All rights reserved.

Pulse transit time differential measurement by fiber Bragg grating pulse recorder.

PubMed

Umesh, Sharath; Padma, Srivani; Ambastha, Shikha; Kalegowda, Anand; Asokan, Sundarrajan

2015-05-01

The present study reports a noninvasive technique for the measurement of the pulse transit time differential (PTTD) from the pulse pressure waveforms obtained at the carotid artery and radial artery using fiber Bragg grating pulse recorders (FBGPR). PTTD is defined as the time difference between the arrivals of a pulse pressure waveform at the carotid and radial arterial sites. The PTTD is investigated as an indicator of variation in the systolic blood pressure. The results are validated against blood pressure variation obtained from a Mindray Patient Monitor. Furthermore, the pulse wave velocity computed from the obtained PTTD is compared with the pulse wave velocity obtained from the color Doppler ultrasound system and is found to be in good agreement. The major advantage of the PTTD measurement via FBGPRs is that the data acquisition system employed can simultaneously acquire pulse pressure waveforms from both FBGPRs placed at carotid and radial arterial sites with a single time scale, which eliminates time synchronization complexity.

Pressure suppression containment system for boiling water reactor

DOEpatents

Gluntz, D.M.; Nesbitt, L.B.

1997-01-21

A system is disclosed for suppressing the pressure inside the containment of a BWR following a postulated accident. A piping subsystem is provided which features a main process pipe that communicates the wetwell airspace to a connection point downstream of the guard charcoal bed in an offgas system and upstream of the main bank of delay charcoal beds which give extensive holdup to offgases. The main process pipe is fitted with both inboard and outboard containment isolation valves. Also incorporated in the main process pipe is a low-differential-pressure rupture disk which prevents any gas outflow in this piping whatsoever until or unless rupture occurs by virtue of pressure inside this main process pipe on the wetwell airspace side of the disk exceeding the design opening (rupture) pressure differential. The charcoal holds up the radioactive species in the noncondensable gas from the wetwell plenum by adsorption, allowing time for radioactive decay before the gas is vented to the environs. 3 figs.

Multisensor System for Isotemporal Measurements to Assess Indoor Climatic Conditions in Poultry Farms

PubMed Central

Bustamante, Eliseo; Guijarro, Enrique; García-Diego, Fernando-Juan; Balasch, Sebastián; Hospitaler, Antonio; Torres, Antonio G.

2012-01-01

The rearing of poultry for meat production (broilers) is an agricultural food industry with high relevance to the economy and development of some countries. Periodic episodes of extreme climatic conditions during the summer season can cause high mortality among birds, resulting in economic losses. In this context, ventilation systems within poultry houses play a critical role to ensure appropriate indoor climatic conditions. The objective of this study was to develop a multisensor system to evaluate the design of the ventilation system in broiler houses. A measurement system equipped with three types of sensors: air velocity, temperature and differential pressure was designed and built. The system consisted in a laptop, a data acquisition card, a multiplexor module and a set of 24 air temperature, 24 air velocity and two differential pressure sensors. The system was able to acquire up to a maximum of 128 signals simultaneously at 5 second intervals. The multisensor system was calibrated under laboratory conditions and it was then tested in field tests. Field tests were conducted in a commercial broiler farm under four different pressure and ventilation scenarios in two sections within the building. The calibration curves obtained under laboratory conditions showed similar regression coefficients among temperature, air velocity and pressure sensors and a high goodness fit (R2 = 0.99) with the reference. Under field test conditions, the multisensor system showed a high number of input signals from different locations with minimum internal delay in acquiring signals. The variation among air velocity sensors was not significant. The developed multisensor system was able to integrate calibrated sensors of temperature, air velocity and differential pressure and operated succesfully under different conditions in a mechanically-ventilated broiler farm. This system can be used to obtain quasi-instantaneous fields of the air velocity and temperature, as well as differential pressure maps to assess the design and functioning of ventilation system and as a verification and validation (V&V) system of Computational Fluid Dynamics (CFD) simulations in poultry farms. PMID:22778611

Positive selection of digestive Cys proteases in herbivorous Coleoptera.

PubMed

Vorster, Juan; Rasoolizadeh, Asieh; Goulet, Marie-Claire; Cloutier, Conrad; Sainsbury, Frank; Michaud, Dominique

2015-10-01

Positive selection is thought to contribute to the functional diversification of insect-inducible protease inhibitors in plants in response to selective pressures exerted by the digestive proteases of their herbivorous enemies. Here we assessed whether a reciprocal evolutionary process takes place on the insect side, and whether ingestion of a positively selected plant inhibitor may translate into a measurable rebalancing of midgut proteases in vivo. Midgut Cys proteases of herbivorous Coleoptera, including the major pest Colorado potato beetle (Leptinotarsa decemlineata), were first compared using a codon-based evolutionary model to look for the occurrence of hypervariable, positively selected amino acid sites among the tested sequences. Hypervariable sites were found, distributed within -or close to- amino acid regions interacting with Cys-type inhibitors of the plant cystatin protein family. A close examination of L. decemlineata sequences indicated a link between their assignment to protease functional families and amino acid identity at positively selected sites. A function-diversifying role for positive selection was further suggested empirically by in vitro protease assays and a shotgun proteomic analysis of L. decemlineata Cys proteases showing a differential rebalancing of protease functional family complements in larvae fed single variants of a model cystatin mutated at positively selected amino acid sites. These data confirm overall the occurrence of hypervariable, positively selected amino acid sites in herbivorous Coleoptera digestive Cys proteases. They also support the idea of an adaptive role for positive selection, useful to generate functionally diverse proteases in insect herbivores ingesting functionally diverse, rapidly evolving dietary cystatins. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

Relative Position of the Third Characteristic Peak of the Intracranial Pressure Pulse Waveform Morphology Differentiates Normal-Pressure Hydrocephalus Shunt Responders and Nonresponders.

PubMed

Hamilton, Robert; Fuller, Jennifer; Baldwin, Kevin; Vespa, Paul; Hu, Xiao; Bergsneider, Marvin

2016-01-01

The diversion of cerebrospinal fluid (CSF) remains the principal treatment option for patients with normal-pressure hydrocephalus (NPH). External lumbar drain (ELD) and overnight intracranial pressure (ICP) monitoring are popular prognostic tests for differentiating which patients will benefit from shunting. Using the morphological clustering and analysis of continuous intracranial pulse (MOCAIP) algorithm to extract morphological metrics from the overnight ICP signal, we hypothesize that changes in the third peak of the ICP pulse pressure waveform can be used to differentiate ELD responders and nonresponders. Our study involved 66 patients (72.2 ± 9.8 years) undergoing evaluation for possible NPH, which included overnight ICP monitoring and ELD. ELD outcome was based on clinical notes and divided into nonresponders and responders. MOCAIP was used to extract mean ICP, ICP wave amplitude (waveAmp), and a metric derived to study P3 elevation (P3ratio). Of the 66 patients, 7 were classified as nonresponders and 25 as significant responders. The mean ICP and waveAmp did not vary significantly (p = 0.19 and p = 0.41) between the outcome groups; however, the P3ratio did show a significant difference (p = 0.04). Initial results suggest that the P3ratio might be used as a prognostic indicator for ELD outcome.

Genome Wide Adaptations of Plasmodium falciparum in Response to Lumefantrine Selective Drug Pressure

PubMed Central

Mwai, Leah; Diriye, Abdi; Masseno, Victor; Muriithi, Steven; Feltwell, Theresa; Musyoki, Jennifer; Lemieux, Jacob; Feller, Avi; Mair, Gunnar R.; Marsh, Kevin; Newbold, Chris; Nzila, Alexis; Carret, Céline K.

2012-01-01

The combination therapy of the Artemisinin-derivative Artemether (ART) with Lumefantrine (LM) (Coartem®) is an important malaria treatment regimen in many endemic countries. Resistance to Artemisinin has already been reported, and it is feared that LM resistance (LMR) could also evolve quickly. Therefore molecular markers which can be used to track Coartem® efficacy are urgently needed. Often, stable resistance arises from initial, unstable phenotypes that can be identified in vitro. Here we have used the Plasmodium falciparum multidrug resistant reference strain V1S to induce LMR in vitro by culturing the parasite under continuous drug pressure for 16 months. The initial IC50 (inhibitory concentration that kills 50% of the parasite population) was 24 nM. The resulting resistant strain V1SLM, obtained after culture for an estimated 166 cycles under LM pressure, grew steadily in 378 nM of LM, corresponding to 15 times the IC50 of the parental strain. However, after two weeks of culturing V1SLM in drug-free medium, the IC50 returned to that of the initial, parental strain V1S. This transient drug tolerance was associated with major changes in gene expression profiles: using the PFSANGER Affymetrix custom array, we identified 184 differentially expressed genes in V1SLM. Among those are 18 known and putative transporters including the multidrug resistance gene 1 (pfmdr1), the multidrug resistance associated protein and the V-type H+ pumping pyrophosphatase 2 (pfvp2) as well as genes associated with fatty acid metabolism. In addition we detected a clear selective advantage provided by two genomic loci in parasites grown under LM drug pressure, suggesting that all, or some of those genes contribute to development of LM tolerance – they may prove useful as molecular markers to monitor P. falciparum LM susceptibility. PMID:22384044

Ecological release and venom evolution of a predatory marine snail at Easter Island.

PubMed

Duda, Thomas F; Lee, Taehwan

2009-05-20

Ecological release is coupled with adaptive radiation and ecological diversification yet little is known about the molecular basis of phenotypic changes associated with this phenomenon. The venomous, predatory marine gastropod Conus miliaris has undergone ecological release and exhibits increased dietary breadth at Easter Island. We examined the extent of genetic differentiation of two genes expressed in the venom of C. miliaris among samples from Easter Island, American Samoa and Guam. The population from Easter Island exhibits unique frequencies of alleles that encode distinct peptides at both loci. Levels of divergence at these loci exceed observed levels of divergence observed at a mitochondrial gene region at Easter Island. Patterns of genetic variation at two genes expressed in the venom of this C. miliaris suggest that selection has operated at these genes and contributed to the divergence of venom composition at Easter Island. These results show that ecological release is associated with strong selection pressures that promote the evolution of new phenotypes.

Expert systems for fault diagnosis in nuclear reactor control

NASA Astrophysics Data System (ADS)

Jalel, N. A.; Nicholson, H.

1990-11-01

An expert system for accident analysis and fault diagnosis for the Loss Of Fluid Test (LOFT) reactor, a small scale pressurized water reactor, was developed for a personal computer. The knowledge of the system is presented using a production rule approach with a backward chaining inference engine. The data base of the system includes simulated dependent state variables of the LOFT reactor model. Another system is designed to assist the operator in choosing the appropriate cooling mode and to diagnose the fault in the selected cooling system. The response tree, which is used to provide the link between a list of very specific accident sequences and a set of generic emergency procedures which help the operator in monitoring system status, and to differentiate between different accident sequences and select the correct procedures, is used to build the system knowledge base. Both systems are written in TURBO PROLOG language and can be run on an IBM PC compatible with 640k RAM, 40 Mbyte hard disk and color graphics.

Mechanical Design and Testing of an Instrumented Rocker-Bogie Mobility System for the Kapvik Micro-Rover

NASA Astrophysics Data System (ADS)

Setterfield, T.

The rocker-bogie mobility system is a six-wheeled mobility system with the ability to equilibrate ground pressure amongst its wheels and traverse obstacles up to one wheel diameter in height; it has been used previously on NASA's Sojourner, Spirit, Opportunity and Curiosity rovers. This paper presents the mechanical design of an instrumented rocker-bogie mobility system for Kapvik, a 30 kg planetary micro-rover prototype developed for the Canadian Space Agency. The design of the wheel drive system is presented, including: motor selection, gear train selection, and performance limits. The design of a differential mechanism, which minimizes the pitch angle of the rover body, is provided. Design considerations for the integration of single-axis force sensors above the wheel hubs are presented. Structural analysis of the rocker and bogie links is outlined. The cross-hill and uphill-downhill static stability of Kapvik is investigated. Load cell and joint position data from testing during obstacle negotiation and uphill operation are presented.

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.

Wet powder seal for gas containment

DOEpatents

Stang, Louis G.

1982-01-01

A gas seal is formed by a compact layer of an insoluble powder and liquid filling the fine interstices of that layer. The smaller the particle size of the selected powder, such as sand or talc, the finer will be the interstices or capillary spaces in the layer and the greater will be the resulting sealing capacity, i.e., the gas pressure differential which the wet powder layer can withstand. Such wet powder seal is useful in constructing underground gas reservoirs or storage cavities for nuclear wastes as well as stopping leaks in gas mains buried under ground or situated under water. The sealing capacity of the wet powder seal can be augmented by the hydrostatic head of a liquid body established over the seal.

Wet powder seal for gas containment

DOEpatents

Stang, L.G.

1979-08-29

A gas seal is formed by a compact layer of an insoluble powder and liquid filling the fine interstices of that layer. The smaller the particle size of the selected powder, such as sand or talc, the finer will be the interstices or capillary spaces in the layer and the greater will be the resulting sealing capacity, i.e., the gas pressure differential which the wet powder layer can withstand. Such wet powder seal is useful in constructing underground gas reservoirs or storage cavities for nuclear wastes as well as stopping leaks in gas mains buried under ground or situated under water. The sealing capacity of the wet powder seal can be augmented by the hydrostatic head of a liquid body established over the seal.

Hybrid Equation/Agent-Based Model of Ischemia-Induced Hyperemia and Pressure Ulcer Formation Predicts Greater Propensity to Ulcerate in Subjects with Spinal Cord Injury

PubMed Central

Solovyev, Alexey; Mi, Qi; Tzen, Yi-Ting; Brienza, David; Vodovotz, Yoram

2013-01-01

Pressure ulcers are costly and life-threatening complications for people with spinal cord injury (SCI). People with SCI also exhibit differential blood flow properties in non-ulcerated skin. We hypothesized that a computer simulation of the pressure ulcer formation process, informed by data regarding skin blood flow and reactive hyperemia in response to pressure, could provide insights into the pathogenesis and effective treatment of post-SCI pressure ulcers. Agent-Based Models (ABM) are useful in settings such as pressure ulcers, in which spatial realism is important. Ordinary Differential Equation-based (ODE) models are useful when modeling physiological phenomena such as reactive hyperemia. Accordingly, we constructed a hybrid model that combines ODEs related to blood flow along with an ABM of skin injury, inflammation, and ulcer formation. The relationship between pressure and the course of ulcer formation, as well as several other important characteristic patterns of pressure ulcer formation, was demonstrated in this model. The ODE portion of this model was calibrated to data related to blood flow following experimental pressure responses in non-injured human subjects or to data from people with SCI. This model predicted a higher propensity to form ulcers in response to pressure in people with SCI vs. non-injured control subjects, and thus may serve as novel diagnostic platform for post-SCI ulcer formation. PMID:23696726

Compartment Venting Analyses of Ares I First Stage Systems Tunnel

NASA Technical Reports Server (NTRS)

Wang, Qunzhen; Arner, Stephen

2009-01-01

Compartment venting analyses have been performed for the Ares I first stage systems tunnel using both the lumped parameter method and the three-dimensional (31)) transient computational fluid dynamics (CFD) approach. The main objective of venting analyses is to predict the magnitudes of differential pressures across the skin so the integrity of solid walls can be evaluated and properly designed. The lumped parameter method assumes the gas pressure and temperature inside the systems tunnel are spatially uniform, which is questionable since the tunnel is about 1,700 in. long and 4 in. wide. Therefore, 31) transient CFD simulations using the commercial CFD code FLUENT are performed in order to examine the gas pressure and temperature variations inside the tunnel. It was found that the uniform pressure and temperature assumptions inside the systems tunnel are valid during ascent. During reentry, the uniform pressure assumption is also reasonable but the uniform temperature assumption is not valid. Predicted pressure and temperature inside the systems tunnel using CFD are also compared with those from the lumped parameter method using the NASA code CHCHVENT. In general, the average pressure and temperature inside the systems tunnel from CFD are between the burst and crush results from CHCHVENT during both ascent and reentry. The skin differential pressure and pressure inside the systems tunnel relative to freestream pressure from CHCHVENT as well as velocity vectors and streamlines are also discussed in detail.

Spatial and ecological population genetic structures within two island-endemic Aeonium species of different niche width.

PubMed

Harter, David E V; Thiv, Mike; Weig, Alfons; Jentsch, Anke; Beierkuhnlein, Carl

2015-10-01

The Crassulacean genus Aeonium is a well-known example for plant species radiation on oceanic archipelagos. However, while allopatric speciation among islands is documented for this genus, the role of intra-island speciation due to population divergence by topographical isolation or ecological heterogeneity has not yet been addressed. The aim of this study was to investigate intraspecific genetic structures and to identify spatial and ecological drivers of genetic population differentiation on the island scale. We analyzed inter simple sequence repeat variation within two island-endemic Aeonium species of La Palma: one widespread generalist that covers a large variety of different habitat types (Ae. davidbramwellii) and one narrow ecological specialist (Ae. nobile), in order to assess evolutionary potentials on this island. Gene pool differentiation and genetic diversity patterns were associated with major landscape structures in both species, with phylogeographic implications. However, overall levels of genetic differentiation were low. For the generalist species, outlier loci detection and loci-environment correlation approaches indicated moderate signatures of divergent selection pressures linked to temperature and precipitation variables, while the specialist species missed such patterns. Our data point to incipient differentiation among populations, emphasizing that ecological heterogeneity and topographical structuring within the small scales of an island can foster evolutionary processes. Very likely, such processes have contributed to the radiation of Aeonium on the Canary Islands. There is also support for different evolutionary mechanisms between generalist and specialist species.

Differential proteomics reveals novel insights into Nosema-honey bee interactions.

PubMed

Kurze, Christoph; Dosselli, Ryan; Grassl, Julia; Le Conte, Yves; Kryger, Per; Baer, Boris; Moritz, Robin F A

2016-12-01

Host manipulation is a common strategy by parasites to reduce host defense responses, enhance development, host exploitation, reproduction and, ultimately, transmission success. As these parasitic modifications can reduce host fitness, increased selection pressure may result in reciprocal adaptations of the host. Whereas the majority of studies on host manipulation have explored resistance against parasites (i.e. ability to prevent or limit an infection), data describing tolerance mechanisms (i.e. ability to limit harm of an infection) are scarce. By comparing differential protein abundance, we provide evidence of host-parasite interactions in the midgut proteomes of N. ceranae-infected and uninfected honey bees from both Nosema-tolerant and Nosema-sensitive lineages. We identified 16 proteins out of 661 protein spots that were differentially abundant between experimental groups. In general, infections of Nosema resulted in an up-regulation of the bee's energy metabolism. Additionally, we identified 8 proteins that were differentially abundant between tolerant and sensitive honey bees regardless of the Nosema infection. Those proteins were linked to metabolism, response to oxidative stress and apoptosis. In addition to bee proteins, we also identified 3 Nosema ceranae proteins. Interestingly, abundance of two of these Nosema proteins were significantly higher in infected Nosema-sensitive honeybees relative to the infected Nosema-tolerant lineage. This may provide a novel candidate for studying the molecular interplay between N. ceranae and its honey bee host in more detail. Copyright © 2016 Elsevier Ltd. All rights reserved.

Development, validity and reliability of a new pressure air biofeedback device (PAB) for measuring isometric extension strength of the lumbar spine.

PubMed

Pienaar, Andries W; Barnard, Justhinus G

2017-04-01

This study describes the development of a new portable muscle testing device, using air pressure as a biofeedback and strength testing tool. For this purpose, a pressure air biofeedback device (PAB ® ) was developed to measure and record the isometric extension strength of the lumbar multifidus muscle in asymptomatic and low back pain (LBP) persons. A total of 42 subjects (age 47.58 years, ±18.58) participated in this study. The validity of PAB ® was assessed by comparing a selected measure, air pressure force in millibar (mb), to a standard criterion; calibrated weights in kilograms (kg) during day-to-day tests. Furthermore, clinical trial-to-trial and day-to-day tests of maximum voluntary isometric contraction (MVIC) of L5 lumbar multifidus were done to compare air pressure force (mb) to electromyography (EMG) in microvolt (μV) and to measure the reliability of PAB ® . A highly significant relationship were found between air pressure output (mb) and calibrated weights (kg). In addition, Pearson correlation calculations showed a significant relationship between PAB ® force (mb) and EMG activity (μV) for all subjects (n = 42) examined, as well as for the asymptomatic group (n = 24). No relationship was detected for the LBP group (n = 18). In terms of lumbar extension strength, we found that asymptomatic subjects were significantly stronger than LBP subjects. The results of the PAB ® test differentiated between LBP and asymptomatic subject's lumbar isometric extension strength without any risk to the subjects and also indicate that the lumbar isometric extension test with the new PAB ® device is reliable and valid.

Biocultural research in global mental health: mapping idioms of distress onto blood pressure in a population survey.

PubMed

Sancilio, Amelia; Eggerman, Mark; Panter-Brick, Catherine

2017-01-01

Biocultural research remains a challenge in the field of global mental health. We sought to test associations between blood pressure and idioms of distress in a population survey. We drew on a randomly selected sample of 991 adults (498 men, 493 women) in Afghanistan, for whom physiological and psychosocial data were systematically collected. Assessment of mental health (Self-Reported Questionnaire, Afghan Symptom Checklist) included conceptualizations of distress related to pressure (fishar), anxiety, and dysphoria, as well as dimensions of negative affect and aggression. We used principal component analysis to map survey responses to fishar, and multiple regressions to examine associations with systolic/diastolic blood pressure, controlling for age, body mass index, and wealth, and differentiating by gender, mental health, and medication. The Afghan sample averaged 129/80 mmHg, with 27.14% of hypertensive individuals. SBP showed inverse associations with reports of low fishar (β = -4.58, P < .001) and high fishar (β = 6.90, P < .001), as did DPB with low fishar (β = -1.55, P < .001) and high fishar (β = 3.77, P < .001). Low and high fishar responses accounted for substantial proportions of SBP data variation (R 2  = 20% and R 2  = 24%), especially in adults on blood pressure medication (R 2  = 58% and R 2  = 49%). Subjective reports of fishar map onto physiological blood pressure more robustly than other conceptualizations of mental distress related to anxiety, dysphoria, negative affect, or aggression. Our results point to the utility of mapping biological and cultural measures of stress and distress, advancing biopsychosocial understandings of wellbeing in global mental health surveys. © 2016 Wiley Periodicals, Inc.

DRIFTSEL: an R package for detecting signals of natural selection in quantitative traits.

PubMed

Karhunen, M; Merilä, J; Leinonen, T; Cano, J M; Ovaskainen, O

2013-07-01

Approaches and tools to differentiate between natural selection and genetic drift as causes of population differentiation are of frequent demand in evolutionary biology. Based on the approach of Ovaskainen et al. (2011), we have developed an R package (DRIFTSEL) that can be used to differentiate between stabilizing selection, diversifying selection and random genetic drift as causes of population differentiation in quantitative traits when neutral marker and quantitative genetic data are available. Apart from illustrating the use of this method and the interpretation of results using simulated data, we apply the package on data from three-spined sticklebacks (Gasterosteus aculeatus) to highlight its virtues. DRIFTSEL can also be used to perform usual quantitative genetic analyses in common-garden study designs. © 2013 John Wiley & Sons Ltd.

Application of Zen sitting principles to microscopic surgery seating.

PubMed

Noro, Kageyu; Naruse, Tetsuya; Lueder, Rani; Nao-I, Nobuhisa; Kozawa, Maki

2012-03-01

This paper describes the application of an alternative seating concept for surgeons that reflects the research of Zen sitting postures, which require Zazen meditators to maintain fixed postures for long durations. The aim of this alternative approach is to provide sitters with a seat pan with sacral support(1) that provides a more even distribution of seat pressures, induces forward pelvic rotation and improves lumbar, buttock and thigh support. This approach was applied to the development of a chair for microscopic surgery. The experimental chair is a seat pan that closely matches the three-dimensional contours of the user's buttocks. Seat comfort was evaluated by comparing both changes in pelvic tilt and seat pressure distributions using Regionally-Differentiated Pressure Maps (RDPM) with subjective ratings of surgeons while operating in prototype and conventional chairs. Findings include that the sacral support of the prototype chair prevents backward pelvic rotation, as seen in zazen (Zen sitting postures). Preliminary data suggests that the prototype provided greater sitting comfort and support for constrained operating postures than did the conventional chair. These findings support the selective application of concave-shaped seat pans that conform to users' buttocks and reflect Zen sitting principles. Copyright © 2011 Elsevier Ltd and The Ergonomics Society. All rights reserved.

Overweight female rats selectively breed for low aerobic capacity exhibit increased myocardial fibrosis and diastolic dysfunction

PubMed Central

Johnson, Megan S.; Ma, Lixin; Pulakat, Lakshmi; Mugerfeld, Irina; Hayden, Melvin R.; Garro, Mona; Knight, William; Britton, Steven L.; Koch, Lauren G.; Sowers, James R.

2012-01-01

The statistical association between endurance exercise capacity and cardiovascular disease suggests that impaired aerobic metabolism underlies the cardiovascular disease risk in men and women. To explore this connection, we applied divergent artificial selection in rats to develop low-capacity runner (LCR) and high-capacity runner (HCR) rats and found that disease risks segregated strongly with low running capacity. Here, we tested if inborn low aerobic capacity promotes differential sex-related cardiovascular effects. Compared with HCR males (HCR-M), LCR males (LCR-M) were overweight by 34% and had heavier retroperitoneal, epididymal, and omental fat pads; LCR females (LCR-F) were 20% heavier than HCR females (HCR-F), and their retroperitoneal, but not perireproductive or omental, fat pads were heavier as well. Unlike HCR-M, blood pressure was elevated in LCR-M, and this was accompanied by left ventricular (LV) hypertrophy. Like HCR-F, LCR-F exhibited normal blood pressure and LV weight as well as increased spontaneous cage activity compared with males. Despite normal blood pressures, LCR-F exhibited increased myocardial interstitial fibrosis and diastolic dysfunction, as indicated by increased LV stiffness, a decrease in the initial filling rate, and an increase in diastolic relaxation time. Although females exhibited increased arterial stiffness, ejection fraction was normal. Increased interstitial fibrosis and diastolic dysfunction in LCR-F was accompanied by the lowest protein levels of phosphorylated AMP-actived protein kinase [phospho-AMPK (Thr172)] and silent information regulator 1. Thus, the combination of risk factors, including female sex, intrinsic low aerobic capacity, and overweightness, promote myocardial stiffness/fibrosis sufficient to induce diastolic dysfunction in the absence of hypertension and LV hypertrophy. PMID:22345570

Evolution of complete proteomes: guanine-cytosine pressure, phylogeny and environmental influences blend the proteomic architecture

PubMed Central

2013-01-01

Background Guanine-cytosine (GC) composition is an important feature of genomes. Likewise, amino acid composition is a distinct, but less valued, feature of proteomes. A major concern is that it is not clear what valuable information can be acquired from amino acid composition data. To address this concern, in-depth analyses of the amino acid composition of the complete proteomes from 63 archaea, 270 bacteria, and 128 eukaryotes were performed. Results Principal component analysis of the amino acid matrices showed that the main contributors to proteomic architecture were genomic GC variation, phylogeny, and environmental influences. GC pressure drove positive selection on Ala, Arg, Gly, Pro, Trp, and Val, and adverse selection on Asn, Lys, Ile, Phe, and Tyr. The physico-chemical framework of the complete proteomes withstood GC pressure by frequency complementation of GC-dependent amino acid pairs with similar physico-chemical properties. Gln, His, Ser, and Val were responsible for phylogeny and their constituted components could differentiate archaea, bacteria, and eukaryotes. Environmental niche was also a significant factor in determining proteomic architecture, especially for archaea for which the main amino acids were Cys, Leu, and Thr. In archaea, hyperthermophiles, acidophiles, mesophiles, psychrophiles, and halophiles gathered successively along the environment-based principal component. Concordance between proteomic architecture and the genetic code was also related closely to genomic GC content, phylogeny, and lifestyles. Conclusions Large-scale analyses of the complete proteomes of a wide range of organisms suggested that amino acid composition retained the trace of GC variation, phylogeny, and environmental influences during evolution. The findings from this study will help in the development of a global understanding of proteome evolution, and even biological evolution. PMID:24088322

Nerve Growth Factor: Early Studies And Recent Clinical Trials.

PubMed

Rocco, Maria Luisa; Soligo, Marzia; Manni, Luigi; Aloe, Luigi

2018-04-11

Since its discovery, nerve growth factor (NGF) has long occupied a critical role in developmental and adult neurobiology for its many important regulatory functions on the survival, growth and differentiation of nerve cells in the peripheral and central nervous system. NGF is the first discovered member of a family of neurotrophic factors, collectively indicated as neurotrophins, (which include brain-derived neurotrophic factor, neurotrophin-3 and neurotrophin 4/5). NGF was discovered for its action on the survival and differentiation of selected populations of peripheral neurons. Since then, an enormous number of basic and human studies were undertaken to explore the role of purified NGF to prevent the death of NGF-receptive cells. These studies revealed that NGF possesses important therapeutic properties, after topical administration, on human cutaneous pressure ulcer, corneal ulcers, glaucoma, retinal maculopathy, Retinitis Pigmentosa and in pediatric optic gliomas and brain traumas. The aim of this review is to present our previous, recent and ongoing clinical studies on the therapeutic properties of NGF. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A differential optical absorption spectroscopy method for retrieval from ground-based Fourier transform spectrometers measurements of the direct solar beam

NASA Astrophysics Data System (ADS)

Huo, Yanfeng; Duan, Minzheng; Tian, Wenshou; Min, Qilong

2015-08-01

A differential optical absorption spectroscopy (DOAS)-like algorithm is developed to retrieve the column-averaged dryair mole fraction of carbon dioxide from ground-based hyper-spectral measurements of the direct solar beam. Different to the spectral fitting method, which minimizes the difference between the observed and simulated spectra, the ratios of multiple channel-pairs—one weak and one strong absorption channel—are used to retrieve from measurements of the shortwave infrared (SWIR) band. Based on sensitivity tests, a super channel-pair is carefully selected to reduce the effects of solar lines, water vapor, air temperature, pressure, instrument noise, and frequency shift on retrieval errors. The new algorithm reduces computational cost and the retrievals are less sensitive to temperature and H2O uncertainty than the spectral fitting method. Multi-day Total Carbon Column Observing Network (TCCON) measurements under clear-sky conditions at two sites (Tsukuba and Bremen) are used to derive xxxx for the algorithm evaluation and validation. The DOAS-like results agree very well with those of the TCCON algorithm after correction of an airmass-dependent bias.

[Effects of long time different negative pressures on osteogenic differentiation of rabbit bone mesenchymal stem cells].

PubMed

Zhao, Bowen; Zhang, Hongwei; Xu, Qiang; Ge, Quanhu; Li, Bolong; Peng, Xinyu; Wu, Xiangwei

2017-05-01

To investigate the effects of long time different negative pressures on osteogenic diffe-rentiation of rabbit bone mesenchymal stem cells (BMSCs). The rabbit BMSCs were isolated and cultured by density gradient centrifugation. Flow cytometry was used to analyze expression of surface markers. The third passage cells cultured under condition of osteogenic induction and under different negative pressure of 0 mm Hg (control group), 75 mm Hg (low negative pressure group), and 150 mm Hg (high negative pressure group) (1 mm Hg=0.133 kPa), and the negative pressure time was 30 min/h. Cell growth was observed under phase contrast microscopy, and the growth curve was drawn; alkaline phosphatase (ALP) activity was detected by ELISA after induced for 3, 7, and 14 days. The mRNA and protein expressions of collagen type I (COL-I) and osteocalcin (OC) in BMSCs were analyzed by real-time fluorescence quantitative PCR and Western blot. The cultured cells were identified as BMSCs by flow cytometry. The third passage BMSCs exhibited typical long shuttle and irregular shape. Cell proliferation was inhibited with the increase of negative pressure. After induced for 4 days, the cell number of high negative pressure group was significantly less than that in control group and low negative pressure group ( P <0.05), but there was no significant difference between the low negative pressure group and the control group ( P >0.05); at 5-7 days, the cell number showed significant difference between 3 groups ( P <0.05). The greater the negative pressure was, the greater the inhibition of cell proliferation was. There was no significant difference in ALP activity between groups at 3 days after induction ( P >0.05); the ALP activity showed significant difference ( P <0.05) between the high negative pressure group and the control group at 7 days after induction; and significant difference was found in the ALP activity between 3 groups at 14 days after induction ( P <0.05). The greater the negative pressure was, the higher the ALP activity was. Real-time fluorescence quantitative PCR and Western blot detection showed that the mRNA and protein expressions of COL-I and OC protein were significantly higher in low negative pressure group and high negative pressure group than control group ( P <0.05), and in the high negative pressure group than the low negative pressure group ( P <0.05). With the increase of the negative pressure, the osteogenic differentiation ability of BMSCs increases gradually, but the cell proliferation is inhibited.

Simplified combustion noise theory yielding a prediction of fluctuating pressure level

NASA Technical Reports Server (NTRS)

Huff, R. G.

1984-01-01

The first order equations for the conservation of mass and momentum in differential form are combined for an ideal gas to yield a single second order partial differential equation in one dimension and time. Small perturbation analysis is applied. A Fourier transformation is performed that results in a second order, constant coefficient, nonhomogeneous equation. The driving function is taken to be the source of combustion noise. A simplified model describing the energy addition via the combustion process gives the required source information for substitution in the driving function. This enables the particular integral solution of the nonhomogeneous equation to be found. This solution multiplied by the acoustic pressure efficiency predicts the acoustic pressure spectrum measured in turbine engine combustors. The prediction was compared with the overall sound pressure levels measured in a CF6-50 turbofan engine combustor and found to be in excellent agreement.

Hydraulic transients in the long diversion-type hydropower station with a complex differential surge tank.

PubMed

Yu, Xiaodong; Zhang, Jian; Zhou, Ling

2014-01-01

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference.

Hydraulic Transients in the Long Diversion-Type Hydropower Station with a Complex Differential Surge Tank

PubMed Central

Yu, Xiaodong; Zhang, Jian

2014-01-01

Based on the theory of hydraulic transients and the method of characteristics (MOC), a mathematic model of the differential surge tank with pressure-reduction orifices (PROs) and overflow weirs for transient calculation is proposed. The numerical model of hydraulic transients is established using the data of a practical hydropower station; and the probable transients are simulated. The results show that successive load rejection is critical for calculating the maximum pressure in spiral case and the maximum rotating speed of runner when the bifurcated pipe is converging under the surge tank in a diversion-type hydropower station; the pressure difference between two sides of breast wall is large during transient conditions, and it would be more serious when simultaneous load rejections happen after load acceptance; the reasonable arrangement of PROs on breast wall can effectively decrease the pressure difference. PMID:25133213

A preliminary study for identification of candidate AFLP markers under artificial selection for shell color in pearl oyster Pinctada fucata.

PubMed

Zou, Keshu; Zhang, Dianchang; Guo, Huayang; Zhu, Caiyan; Li, Min; Jiang, Shigui

2014-05-25

Pearl oyster Pinctada fucata is widely cultured to produce seawater pearl in South China, and the quality of pearl is significantly affected by its shell color. Thus the Pearl Oyster Selective Breeding Program (POSBP) was carried out for the shell color and growth traits. The black (B), gold (G), red (R) and white (W) shell strains with fast growth trait were achieved after five successive generation selection. In this study, AFLP technique was used to scan genome of four strains with different shell colors to identify the candidate markers under artificial selection. Eight AFLP primer combinations were screened and yielded 688 loci, 676 (98.26%) of which were polymorphic. In black, gold, red and white strains, the percentage of polymorphic loci was 90.41%, 87.79%, 93.60% and 93.31%, respectively, Nei's gene diversity was 0.3225, 0.2829, 0.3221 and 0.3292, Shannon's information index was 0.4801, 0.4271, 0.4825 and 0.4923, and the value of FST was 0.1805. These results suggested that the four different shell color strains had high genetic diversity and great genetic differentiation among strains, which had been subjected to the continuous selective pressures during the artificial selective breeding. Furthermore, six outlier loci were considered as the candidate markers under artificial selection for shell color. This study provides a molecular evidence for the inheritance of shell color of P. fucata. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterizing Structural and Stratigraphic Heterogeneities in a Faulted Aquifer Using Pump Tests with an Array of Westbay Multilevel Monitoring Wells

NASA Astrophysics Data System (ADS)

Johnson, B.; Zhurina, E. N.

2001-12-01

We are developing and assessing field testing and analysis methodologies for quantitative characterization of aquifer heterogenities using data measured in an array of multilevel monitoring wells (MLW) during pumping and recovery well tests. We have developed a unique field laboratory to determine the permeability field in a 20m by 40m by 70m volume in the fault partitioned, siliciclastic Hickory aquifer system in central Texas. The site incorporates both stratigraphic variations and a normal fault system that partially offsets the aquifer and impedes cross-fault flow. We constructed a high-resolution geologic model of the site based upon 1050 m of core and a suite of geophysical logs from eleven, closely spaced (3-10m), continuously cored boreholes to depths of 125 m. Westbay multilevel monitoring systems installed in eight holes provide 94 hydraulically isolated measurement zones and 25 injection zones. A good geologic model is critical to proper installation of the MLW. Packers are positioned at all significant fault piercements and selected, laterally extensive, clay-rich strata. Packers in adjacent MLW bracket selected hydrostratigraphic intervals. Pump tests utilized two, uncased, fully penetrating irrigation wells that straddle the fault system and are in close proximity (7 to 65 m) to the MLW. Pumping and recovery transient pressure histories were measured in 85 zones using pressure transducers with a resolution of 55 Pa (0.008 psi). The hydraulic response is that of an anisotropic, unconfined aquifer. The transient pressure histories vary significantly from zone to zone in a single MLW as well as between adjacent MLW. Derivative plots are especially useful for differentiating details of pressure histories. Based on the geologic model, the derivative curve of a zone reflects its absolute vertical position, vertical stratigraphic position, and proximity to either a fault or significant stratigraphic heterogeneity. Additional forward modeling is needed to assist qualitative interpretation of response curves. Prior geologic knowledge appears critical. Quantitative interpretation of the transient pressure histories requires utilizing a numerical aquifer response model coupled with a geophysical inversion algorithm.

Glacial history affected phenotypic differentiation in the alpine plant, Campanula thyrsoides.

PubMed

Scheepens, J F; Frei, Eva S; Stöcklin, Jürg

2013-01-01

Numerous widespread Alpine plant species show molecular differentiation among populations from distinct regions. This has been explained as the result of genetic drift during glacial survival in isolated refugia along the border of the European Alps. Since genetic drift may affect molecular markers and phenotypic traits alike, we asked whether phenotypic differentiation mirrors molecular patterns among Alpine plant populations from different regions. Phenotypic traits can be under selection, so we additionally investigated whether part of the phenotypic differentiation can be explained by past selection and/or current adaptation. Using the monocarpic Campanula thyrsoides as our study species, a common garden experiment with plants from 21 populations from four phylogeographic groups located in regions across the Alps and the Jura Mountains was performed to test for differentiation in morphological and phenological traits. Past selection was investigated by comparing phenotypic differentiation among and within regions with molecular differentiation among and within regions. The common garden results indicated regional differentiation among populations for all investigated phenotypic traits, particularly in phenology. Delayed flowering in plants from the South-eastern Alps suggested adaptation to long sub-mediterranean summers and contrasted with earlier flowering of plants experiencing shorter growing seasons in regions with higher elevation to the West. Comparisons between molecular and phenotypic differentiation revealed diversifying selection among regions in height and biomass, which is consistent with adaptation to environmental conditions in glacial refugia. Within regions, past selection acted against strong diversification for most phenotypic traits, causing restricted postglacial adaptation. Evidence consistent with post-glacial adaptation was also given by negative correlation coefficients between several phenotypic traits and elevation of the population's origin. In conclusion, our study suggests that, irrespective of adaptation of plants to their current environment, glacial history can have a strong and long-lasting influence on the phenotypic evolution of Alpine plants.

Comparison of three models to estimate breeding values for percentage of loin intramuscular fat in Duroc swine.

PubMed

Newcom, D W; Baas, T J; Stalder, K J; Schwab, C R

2005-04-01

Three selection models were evaluated to compare selection candidate rankings based on EBV and to evaluate subsequent effects of model-derived EBV on the selection differential and expected genetic response in the population. Data were collected from carcass- and ultrasound-derived estimates of loin i.m. fat percent (IMF) in a population of Duroc swine under selection to increase IMF. The models compared were Model 1, a two-trait animal model used in the selection experiment that included ultrasound IMF from all pigs scanned and carcass IMF from pigs slaughtered to estimate breeding values for both carcass (C1) and ultrasound IMF (U1); Model 2, a single-trait animal model that included ultrasound IMF values on all pigs scanned to estimate breeding values for ultrasound IMF (U2); and Model 3, a multiple-trait animal model including carcass IMF from slaughtered pigs and the first three principal components from a total of 10 image parameters averaged across four longitudinal ultrasound images to estimate breeding values for carcass IMF (C3). Rank correlations between breeding value estimates for U1 and C1, U1 and U2, and C1 and C3 were 0.95, 0.97, and 0.92, respectively. Other rank correlations were 0.86 or less. In the selection experiment, approximately the top 10% of boars and 50% of gilts were selected. Selection differentials for pigs in Generation 3 were greatest when ranking pigs based on C1, followed by U1, U2, and C3. In addition, selection differential and estimated response were evaluated when simulating selection of the top 1, 5, and 10% of sires and 50% of dams. Results of this analysis indicated the greatest selection differential was for selection based on C1. The greatest loss in selection differential was found for selection based on C3 when selecting the top 10 and 1% of boars and 50% of gilts. The loss in estimated response when selecting varying percentages of boars and the top 50% of gilts was greatest when selection was based on C3 (16.0 to 25.8%) and least for selection based on U1 (1.3 to 10.9%). Estimated genetic change from selection based on carcass IMF was greater than selection based on ultrasound IMF. Results show that selection based on a combination of ultrasonically predicted IMF and sib carcass IMF produced the greatest selection differentials and should lead to the greatest genetic change.

Modular fuel-cell stack assembly

DOEpatents

Patel, Pinakin [Danbury, CT; Urko, Willam [West Granby, CT

2008-01-29

A modular multi-stack fuel-cell assembly in which the fuel-cell stacks are situated within a containment structure and in which a gas distributor is provided in the structure and distributes received fuel and oxidant gases to the stacks and receives exhausted fuel and oxidant gas from the stacks so as to realize a desired gas flow distribution and gas pressure differential through the stacks. The gas distributor is centrally and symmetrically arranged relative to the stacks so that it itself promotes realization of the desired gas flow distribution and pressure differential.

Upper esophageal sphincter (UES) metrics on high-resolution manometry (HRM) differentiate achalasia subtypes.

PubMed

Blais, P; Patel, A; Sayuk, G S; Gyawali, C P

2017-12-01

The upper esophageal sphincter (UES) reflexively responds to bolus presence within the esophageal lumen, therefore UES metrics can vary in achalasia. Within consecutive patients undergoing esophageal high-resolution manometry (HRM), 302 patients (58.2±1.0 year, 57% F) with esophageal outflow obstruction were identified, and compared to 16 asymptomatic controls (27.7±0.7 year, 56% F). Esophageal outflow obstruction was segregated into achalasia subtypes 1, 2, and 3, and esophagogastric junction outflow obstruction (EGJOO with intact peristalsis) using Chicago Classification v3.0. UES and lower esophageal sphincter (LES) metrics were compared between esophageal outflow obstruction and normal controls using univariate and multivariate analysis. Linear regression excluded multicollinearity of pressure metrics that demonstrated significant differences across individual subtype comparisons. LES integrated relaxation pressure (IRP) had utility in differentiating achalasia from controls (P<.0001), but no utility in segregating between subtypes (P=.27). In comparison to controls, patients collectively demonstrated univariate differences in UES mean basal pressure, relaxation time to nadir, recovery time, and residual pressure (UES-RP) (P≤.049). UES-RP was highest in type 2 achalasia (P<.0001 compared to other subtypes and controls). In multivariate analysis, only UES-RP retained significance in comparison between each of the subgroups (P≤.02 for each comparison). Intrabolus pressure was highest in type 3 achalasia; this demonstrated significant differences across some but not all subtype comparisons. Nadir UES-RP can differentiate achalasia subtypes within the esophageal outflow obstruction spectrum, with highest values in type 2 achalasia. This metric likely represents a surrogate marker for esophageal pressurization. © 2017 John Wiley & Sons Ltd.

Global genetic differentiation of complex traits shaped by natural selection in humans.

PubMed

Guo, Jing; Wu, Yang; Zhu, Zhihong; Zheng, Zhili; Trzaskowski, Maciej; Zeng, Jian; Robinson, Matthew R; Visscher, Peter M; Yang, Jian

2018-05-14

There are mean differences in complex traits among global human populations. We hypothesize that part of the phenotypic differentiation is due to natural selection. To address this hypothesis, we assess the differentiation in allele frequencies of trait-associated SNPs among African, Eastern Asian, and European populations for ten complex traits using data of large sample size (up to ~405,000). We show that SNPs associated with height ([Formula: see text]), waist-to-hip ratio ([Formula: see text]), and schizophrenia ([Formula: see text]) are significantly more differentiated among populations than matched "control" SNPs, suggesting that these trait-associated SNPs have undergone natural selection. We further find that SNPs associated with height ([Formula: see text]) and schizophrenia ([Formula: see text]) show significantly higher variance in linkage disequilibrium (LD) scores across populations than control SNPs. Our results support the hypothesis that natural selection has shaped the genetic differentiation of complex traits, such as height and schizophrenia, among worldwide populations.

Effects of a history of differential reinforcement on preference for choice.

PubMed

Karsina, Allen; Thompson, Rachel H; Rodriguez, Nicole M

2011-03-01

The effects of a history of differential reinforcement for selecting a free-choice versus a restricted-choice stimulus arrangement on the subsequent responding of 7 undergraduates in a computer-based game of chance were examined using a concurrent-chains arrangement and a multiple-baseline-across-participants design. In the free-choice arrangement, participants selected three numbers, in any order, from an array of eight numbers presented on the computer screen. In the restricted-choice arrangement, participants selected the order of three numbers preselected from the array of eight by a computer program. In initial sessions, all participants demonstrated no consistent preference or preference for restricted choice. Differential reinforcement of free-choice selections resulted in increased preference for free choice immediately and in subsequent sessions in the absence of programmed differential outcomes. For 5 participants, changes in preference for choice were both robust and lasting, suggesting that a history of differential reinforcement for choice may affect preference for choice.

Effects of a History of Differential Reinforcement on Preference for Choice

PubMed Central

Karsina, Allen; Thompson, Rachel H; Rodriguez, Nicole M

2011-01-01

The effects of a history of differential reinforcement for selecting a free-choice versus a restricted-choice stimulus arrangement on the subsequent responding of 7 undergraduates in a computer-based game of chance were examined using a concurrent-chains arrangement and a multiple-baseline-across-participants design. In the free-choice arrangement, participants selected three numbers, in any order, from an array of eight numbers presented on the computer screen. In the restricted-choice arrangement, participants selected the order of three numbers preselected from the array of eight by a computer program. In initial sessions, all participants demonstrated no consistent preference or preference for restricted choice. Differential reinforcement of free-choice selections resulted in increased preference for free choice immediately and in subsequent sessions in the absence of programmed differential outcomes. For 5 participants, changes in preference for choice were both robust and lasting, suggesting that a history of differential reinforcement for choice may affect preference for choice. PMID:21541125

Development of a Self-Powered Food Sanitation Center

DTIC Science & Technology

2002-11-01

This pump is capable of priming itself, up to 7 feet of water, and can operate dry without damage. The pump is actuated by a pressure - switch sensing...the pressure of the accumulator. The pressure - switch is set to 45 psi and has a 5 psi differential. 3.8 Mixing Valve The mixing valve...pressure of about 0.8 psi. When the boiler reaches about 0.7 psi, a pressure - switch deactivates the high-fire fuel-control solenoid, bypassing the

HLA Class I Depleted hESC as a Source of Hypoimmunogenic Cells for Tissue Engineering Applications.

PubMed

Karabekian, Zaruhi; Ding, Hao; Stybayeva, Gulnaz; Ivanova, Irina; Muselimyan, Narine; Haque, Amranul; Toma, Ian; Posnack, Nikki G; Revzin, Alexander; Leitenberg, David; Laflamme, Michael A; Sarvazyan, Narine

2015-10-01

Rapidly improving protocols for the derivation of autologous cells from stem cell sources is a welcome development. However, there are many circumstances when off-the-shelf universally immunocompatible cells may be needed. Embryonic stem cells (ESCs) provide a unique opportunity to modify the original source of differentiated cells to minimize their rejection by nonautologous hosts. Immune rejection of nonautologous human embryonic stem cell (hESC) derivatives can be reduced by downregulating human leukocyte antigen (HLA) class I molecules, without affecting the ability of these cells to differentiate into specific lineages. Beta-2-microglobulin (B2M) expression was decreased by lentiviral transduction using human anti-HLA class I light-chain B2M short hairpin RNA. mRNA levels of B2M were decreased by 90% in a RUES2-modified hESC line, as determined by quantitative real time-polymerase chain reaction analysis. The transduced cells were selected under puromycin pressure and maintained in an undifferentiated state. The latter was confirmed by Oct4 and Nanog expression, and by the formation of characteristic round-shaped colonies. B2M downregulation led to diminished HLA-I expression on the cell surface, as determined by flow cytometry. When used as target cells in a mixed lymphocyte reaction assay, transduced hESCs and their differentiated derivatives did not stimulate allogeneic T-cell proliferation. Using a cardiac differentiation protocol, transduced hESCs formed a confluent layer of cardiac myocytes and maintained a low level of B2M expression. Transduced hESCs were also successfully differentiated into a hepatic lineage, validating their capacity to differentiate into multiple lineages. HLA-I depletion does not preclude hESC differentiation into cardiac or hepatic lineages. This methodology can be used to engineer tissue from nonautologous hESC sources with improved immunocompatibility.

HLA Class I Depleted hESC as a Source of Hypoimmunogenic Cells for Tissue Engineering Applications

PubMed Central

Karabekian, Zaruhi; Ding, Hao; Stybayeva, Gulnaz; Ivanova, Irina; Muselimyan, Narine; Haque, Amranul; Toma, Ian; Posnack, Nikki G.; Revzin, Alexander; Leitenberg, David; Laflamme, Michael A.

2015-01-01

Background: Rapidly improving protocols for the derivation of autologous cells from stem cell sources is a welcome development. However, there are many circumstances when off-the-shelf universally immunocompatible cells may be needed. Embryonic stem cells (ESCs) provide a unique opportunity to modify the original source of differentiated cells to minimize their rejection by nonautologous hosts. Hypothesis: Immune rejection of nonautologous human embryonic stem cell (hESC) derivatives can be reduced by downregulating human leukocyte antigen (HLA) class I molecules, without affecting the ability of these cells to differentiate into specific lineages. Methods and Results: Beta-2-microglobulin (B2M) expression was decreased by lentiviral transduction using human anti-HLA class I light-chain B2M short hairpin RNA. mRNA levels of B2M were decreased by 90% in a RUES2-modified hESC line, as determined by quantitative real time-polymerase chain reaction analysis. The transduced cells were selected under puromycin pressure and maintained in an undifferentiated state. The latter was confirmed by Oct4 and Nanog expression, and by the formation of characteristic round-shaped colonies. B2M downregulation led to diminished HLA-I expression on the cell surface, as determined by flow cytometry. When used as target cells in a mixed lymphocyte reaction assay, transduced hESCs and their differentiated derivatives did not stimulate allogeneic T-cell proliferation. Using a cardiac differentiation protocol, transduced hESCs formed a confluent layer of cardiac myocytes and maintained a low level of B2M expression. Transduced hESCs were also successfully differentiated into a hepatic lineage, validating their capacity to differentiate into multiple lineages. Conclusions: HLA-I depletion does not preclude hESC differentiation into cardiac or hepatic lineages. This methodology can be used to engineer tissue from nonautologous hESC sources with improved immunocompatibility. PMID:26218149

Shock Reactivity of Non-Porous Mixtures of Manganese and Sulfur

NASA Astrophysics Data System (ADS)

Jette, Francois-Xavier; Goroshin, Samuel; Higgins, Andrew

2007-06-01

Stoichiometric mixtures of manganese powder and sulfur were melt-cast into solid pellets in order to study the mechanism of shock-enhanced reactivity in non-porous heterogeneous mixtures. This mixture was selected due to the large exothermic heat release of the manganese-sulfur reaction (214 kJ/mol), which causes the reaction to be self-sustaining once initiated. The test samples were placed in planar recovery ampoules and a strong shock was delivered via the detonation of a charge of amine-sensitized nitromethane. Various shock strengths were achieved by placing different thicknesses of PMMA attenuator between the explosive charge and the ampoule. The results confirmed that shock-induced reactions can be produced in the absence of porosity. Indeed, the critical shock pressure that caused ignition of the mixture in the ampoule was found to be in the range 2.2 - 3.8 GPa (pressures were estimated using LS-DYNA simulations). In the cases where the shock was too weak to cause ignition in the ampoule, the sample was extracted and its ignition temperature was determined using a differential thermal analyzer.

TRPV4 channels: physiological and pathological role in cardiovascular system.

PubMed

Randhawa, Puneet Kaur; Jaggi, Amteshwar Singh

2015-11-01

TRPV4 channels are non-selective cation channels permeable to Ca(2+), Na(+), and Mg(2+) ions. Recently, TRPV4 channels have received considerable attention as these channels are widely expressed in the cardiovascular system including endothelial cells, cardiac fibroblasts, vascular smooth muscles, and peri-vascular nerves. Therefore, these channels possibly play a pivotal role in the maintenance of cardiovascular homeostasis. TRPV4 channels critically regulate flow-induced arteriogenesis, TGF-β1-induced differentiation of cardiac fibroblasts into myofibroblasts, and heart failure-induced pulmonary edema. These channels also mediate hypoxia-induced increase in proliferation and migration of pulmonary artery smooth muscle cells and progression of pulmonary hypertension. These channels also maintain flow-induced vasodilation and preserve vascular function by directly activating Ca(2+)-dependent KCa channels. Furthermore, these may also induce vasodilation and maintain blood pressure indirectly by evoking the release of NO, CGRP, and substance P. The present review discusses the evidences and the potential mechanisms implicated in diverse responses including arteriogenesis, cardiac remodeling, congestive heart failure-induced pulmonary edema, pulmonary hypertension, flow-induced dilation, regulation of blood pressure, and hypoxic preconditioning.

Flight calibration tests of a nose-boom-mounted fixed hemispherical flow-direction sensor

NASA Technical Reports Server (NTRS)

Armistead, K. H.; Webb, L. D.

1973-01-01

Flight calibrations of a fixed hemispherical flow angle-of-attack and angle-of-sideslip sensor were made from Mach numbers of 0.5 to 1.8. Maneuvers were performed by an F-104 airplane at selected altitudes to compare the measurement of flow angle of attack from the fixed hemispherical sensor with that from a standard angle-of-attack vane. The hemispherical flow-direction sensor measured differential pressure at two angle-of-attack ports and two angle-of-sideslip ports in diametrically opposed positions. Stagnation pressure was measured at a center port. The results of these tests showed that the calibration curves for the hemispherical flow-direction sensor were linear for angles of attack up to 13 deg. The overall uncertainty in determining angle of attack from these curves was plus or minus 0.35 deg or less. A Mach number position error calibration curve was also obtained for the hemispherical flow-direction sensor. The hemispherical flow-direction sensor exhibited a much larger position error than a standard uncompensated pitot-static probe.

Propellant-Flow-Actuated Rocket Engine Igniter

NASA Technical Reports Server (NTRS)

Wollen, Mark

2013-01-01

A rocket engine igniter has been created that uses a pneumatically driven hammer that, by specialized geometry, is induced into an oscillatory state that can be used to either repeatedly impact a piezoelectric crystal with sufficient force to generate a spark capable of initiating combustion, or can be used with any other system capable of generating a spark from direct oscillatory motion. This innovation uses the energy of flowing gaseous propellant, which by means of pressure differentials and kinetic motion, causes a hammer object to oscillate. The concept works by mass flows being induced through orifices on both sides of a cylindrical tube with one or more vent paths. As the mass flow enters the chamber, the pressure differential is caused because the hammer object is supplied with flow on one side and the other side is opened with access to the vent path. The object then crosses the vent opening and begins to slow because the pressure differential across the ball reverses due to the geometry in the tube. Eventually, the object stops because of the increasing pressure differential on the object until all of the kinetic energy has been transferred to the gas via compression. This is the point where the object reverses direction because of the pressure differential. This behavior excites a piezoelectric crystal via direct impact from the hammer object. The hammer strikes a piezoelectric crystal, then reverses direction, and the resultant high voltage created from the crystal is transferred via an electrode to a spark gap in the ignition zone, thereby providing a spark to ignite the engine. Magnets, or other retention methods, might be employed to favorably position the hammer object prior to start, but are not necessary to maintain the oscillatory behavior. Various manifestations of the igniter have been developed and tested to improve device efficiency, and some improved designs are capable of operation at gas flow rates of a fraction of a gram per second (0.001 lb/s) and pressure drops on the order of 30 to 50 kilopascal (a few psi). An analytical model has been created and tested in conjunction with a precisely calibrated reference model. The analytical model accurately captures the overall behavior of this innovation. The model is a simple "volume-orifice" concept, with each chamber considered a single temperature and pressure "node" connected to adjacent nodes, or to vent paths through flow control orifices. Mass and energy balances are applied to each node, with gas flow predicted using simple compressible flow equations.

A temperature and pressure controlled calibration system for pressure sensors

NASA Technical Reports Server (NTRS)

Chapman, John J.; Kahng, Seun K.

1989-01-01

A data acquisition and experiment control system capable of simulating temperatures from -184 to +220 C and pressures either absolute or differential from 0 to 344.74 kPa is developed to characterize silicon pressure sensor response to temperature and pressure. System software is described that includes sensor data acquisition, algorithms for numerically derived thermal offset and sensitivity correction, and operation of the environmental chamber and pressure standard. This system is shown to be capable of computer interfaced cryogenic testing to within 1 C and 34.47 Pa of single channel or multiplexed arrays of silicon pressure sensors.

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

Advanced Poincaré plot analysis differentiates between hypertensive pregnancy disorders.

PubMed

Seeck, A; Baumert, M; Fischer, C; Khandoker, A; Faber, R; Voss, A

2011-10-01

Hypertensive pregnancy disorders affect 6% to 8% of all pregnancies and can result in severe complications for the mother and the foetus of which pre-eclampsia (PE) has the worst perinatal outcome. Several studies suggested that the autonomic nervous system plays an important role in the process of developing hypertensive pregnancy disorders, especially PE. The aim of this retrospective study was to investigate whether women with PE could be differentiated from women with various other hypertensive pregnancy disorders, by employing an enhanced Poincaré plot analysis (PPA), the segmented Poincaré plot analysis (SPPA), to their beat-to-beat interval and blood pressure signals. Sixty-nine pregnant women with hypertensive disorders (29 PE, 40 with chronic or gestational hypertension) were included. The SPPA as well as the traditional PPA found significant differences between PE and other hypertensive disorders of diastolic blood pressure (p < 0.001 versus p < 0.001) but only the SPPA method revealed significant differences (p < 0.001) also of the systolic blood pressure. Further on, linear discrimination analysis demonstrated that indices derived from SPPA are more suitable for differentiation between chronic and gestational hypertension and PE than those from traditional PPA (area under the ROC curve 0.85 versus 0.69). Therefore this procedure could contribute to the differential diagnosis of hypertensive pregnancy disorders.

The landscape of sex-differential transcriptome and its consequent selection in human adults.

PubMed

Gershoni, Moran; Pietrokovski, Shmuel

2017-02-07

The prevalence of several human morbid phenotypes is sometimes much higher than intuitively expected. This can directly arise from the presence of two sexes, male and female, in one species. Men and women have almost identical genomes but are distinctly dimorphic, with dissimilar disease susceptibilities. Sexually dimorphic traits mainly result from differential expression of genes present in both sexes. Such genes can be subject to different, and even opposing, selection constraints in the two sexes. This can impact human evolution by differential selection on mutations with dissimilar effects on the two sexes. We comprehensively mapped human sex-differential genetic architecture across 53 tissues. Analyzing available RNA-sequencing data from 544 adults revealed thousands of genes differentially expressed in the reproductive tracts and tissues common to both sexes. Sex-differential genes are related to various biological systems, and suggest new insights into the pathophysiology of diverse human diseases. We also identified a significant association between sex-specific gene transcription and reduced selection efficiency and accumulation of deleterious mutations, which might affect the prevalence of different traits and diseases. Interestingly, many of the sex-specific genes that also undergo reduced selection efficiency are essential for successful reproduction in men or women. This seeming paradox might partially explain the high incidence of human infertility. This work provides a comprehensive overview of the sex-differential transcriptome and its importance to human evolution and human physiology in health and in disease.

Genome-Wide Variation Patterns Uncover the Origin and Selection in Cultivated Ginseng (Panax ginseng Meyer).

PubMed

Li, Ming-Rui; Shi, Feng-Xue; Li, Ya-Ling; Jiang, Peng; Jiao, Lili; Liu, Bao; Li, Lin-Feng

2017-09-01

Chinese ginseng (Panax ginseng Meyer) is a medicinally important herb and plays crucial roles in traditional Chinese medicine. Pharmacological analyses identified diverse bioactive components from Chinese ginseng. However, basic biological attributes including domestication and selection of the ginseng plant remain under-investigated. Here, we presented a genome-wide view of the domestication and selection of cultivated ginseng based on the whole genome data. A total of 8,660 protein-coding genes were selected for genome-wide scanning of the 30 wild and cultivated ginseng accessions. In complement, the 45s rDNA, chloroplast and mitochondrial genomes were included to perform phylogenetic and population genetic analyses. The observed spatial genetic structure between northern cultivated ginseng (NCG) and southern cultivated ginseng (SCG) accessions suggested multiple independent origins of cultivated ginseng. Genome-wide scanning further demonstrated that NCG and SCG have undergone distinct selection pressures during the domestication process, with more genes identified in the NCG (97 genes) than in the SCG group (5 genes). Functional analyses revealed that these genes are involved in diverse pathways, including DNA methylation, lignin biosynthesis, and cell differentiation. These findings suggested that the SCG and NCG groups have distinct demographic histories. Candidate genes identified are useful for future molecular breeding of cultivated ginseng. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

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).

Normal pressure hydrocephalus: Diagnostic and predictive evaluationon

PubMed Central

Damasceno, Benito Pereira

2009-01-01

In typical cases, normal pressure hydrocephalus (NPH) manifests itself with the triad of gait disturbance, which begins first, followed by mental deterioration and urinary incontinence associated with ventriculomegaly (on CT or MRI) and normal cerebrospinal fluid (CSF) pressure. These cases present minor diagnostic difficulties and are the most likely to improve after shunting. Problems arise when NPH shows atypical or incomplete clinical manifestations (25–50% of cases) or is mimicked by other diseases. In this scenario, other complementary tests have to be used, preferentially those that can best predict surgical outcome. Radionuclide cisternography, intracranial pressure monitoring (ICP) and lumbar infusion tests can show CSF dynamics malfunction, but none are able to confirm whether the patient will benefit from surgery. The CSF tap test (CSF-TT) is the only procedure that can temporarily simulate the effect of definitive shunt. Since the one tap CSF-TT has low sensitivity, it cannot be used to exclude patients from surgery. In such cases, we have to resort to a repeated CSF-TT (RTT) or continuous lumbar external drainage (LED). The most reliable prediction would be achieved if RTT or LED proved positive, in addition to the occurrence of B-waves during more than 50% of ICP recording time. This review was based on a PubMed literature search from 1966 to date. It focuses on clinical presentation, neuroimaging, complementary prognostic tests, and differential diagnosis of NPH, particularly on the problem of selecting appropriate candidates for shunt. PMID:29213603

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.

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.

Extreme mechanical properties of materials under extreme pressure and temperature conditions (Invited)

NASA Astrophysics Data System (ADS)

Kavner, A.; Armentrout, M. M.; Xie, M.; Weinberger, M.; Kaner, R. B.; Tolbert, S. H.

2010-12-01

A strong synergy ties together the high-pressure subfields of mineral physics, solid-state physics, and materials engineering. The catalog of studies measuring the mechanical properties of materials subjected to large differential stresses in the diamond anvil cell demonstrates a significant pressure-enhancement of strength across many classes of materials, including elemental solids, salts, oxides, silicates, and borides and nitrides. High pressure techniques—both radial diffraction and laser heating in the diamond anvil cell—can be used to characterize the behavior of ultrahard materials under extreme conditions, and help test hypotheses about how composition, structure, and bonding work together to govern the mechanical properties of materials. The principles that are elucidated by these studies can then be used to help design engineering materials to encourage desired properties. Understanding Earth and planetary interiors requires measuring equations of state of relevant materials, including oxides, silicates, and metals under extreme conditions. If these minerals in the diamond anvil cell have any ability to support a differential stress, the assumption of quasi-hydrostaticity no longer applies, with a resulting non-salubrious effect on attempts to measure equation of state. We illustrate these applications with the results of variety of studies from our laboratory and others’ that have used high-pressure radial diffraction techniques and also laser heating in the diamond anvil cell to characterize the mechanical properties of a variety of ultrahard materials, especially osmium metal, osmium diboride, rhenium diboride, and tungsten tetraboride. We compare ambient condition strength studies such as hardness testing with high-pressure studies, especially radial diffraction under differential stress. In addition, we outline criteria for evaluating mechanical properties of materials at combination high pressures and temperatures. Finally, we synthesize our understanding of mechanical properties and composite behavior to suggest new approaches to designing high-pressure experiments to target specific measurements of a wide variety of mechanical properties.

Right ventricular speckle tracking assessment for differentiation of pressure- versus volume-overloaded right ventricle.

PubMed

Werther Evaldsson, Anna; Ingvarsson, Annika; Waktare, Johan; Smith, Gustav J; Thilén, Ulf; Stagmo, Martin; Roijer, Anders; Rådegran, Goran; Meurling, Carl

2017-10-26

Right ventricular (RV) dysfunction may be caused by either pressure or volume overload. RV function is conventionally assessed with echocardiography using tricuspid annular plane systolic excursion (TAPSE), RV fractional area change (RVFAC), tricuspid lateral annular systolic velocity (S') and RV index of myocardial performance (RIMP). The purpose of this study was to evaluate whether RV global longitudinal strain (RVGLS) and RV-free wall strain (RV-free) could add additional information to differentiate these two causes of RV overload. The study enrolled 89 patients with an echocardiographic trans-tricuspid gradient >30 mmHg. Forty-five patients with pulmonary arterial hypertension or chronic thromboembolic pulmonary hypertension (pressure overload) were compared with 44 patients with an atrial septum defect (volume overload). RV size was larger in the volume group (P<0·05). TAPSE and S' were lower in the pressure group (P<0·05, P<0·01). RVFAC was lower in the pressure group (P<0·001) as well as RVGLS (-12·1 ± 3·3% versus -20·2 ± 3·4%, P<0·001) and RV-free (-12·9 ± 3·3% versus -19·4 ± 3·4%, P<0·001). In this study, RVGLS and RV-free could more accurately discriminate RV pressure from volume overload than conventional measures. The reason could be that TAPSE and S' are unable to differentiate active deformation from passive entrainment caused by the left ventricle. The pressure group had evidence of marked RV hypertrophy despite standard functional parameters (TAPSE and S) within normal range. This would enhance the value of strain to more sensitively detect abnormal function. A cut-off value of below -16% for RVGLS and RV-free predicts RV pressure overload with high accuracy. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Proposed moduli of dry rock and their application to predicting elastic velocities of sandstones

USGS Publications Warehouse

Lee, Myung W.

2005-01-01

Velocities of water-saturated isotropic sandstones under low frequency can be modeled using the Biot-Gassmann theory if the moduli of dry rocks are known. On the basis of effective medium theory by Kuster and Toksoz, bulk and shear moduli of dry sandstone are proposed. These moduli are related to each other through a consolidation parameter and provide a new way to calculate elastic velocities. Because this parameter depends on differential pressure and the degree of consolidation, the proposed moduli can be used to calculate elastic velocities of sedimentary rocks under different in-place conditions by varying the consolidation parameter. This theory predicts that the ratio of P-wave to S-wave velocity (Vp/Vs) of a dry rock decreases as differential pressure increases and porosity decreases. This pattern of behavior is similar to that of water-saturated sedimentary rocks. If microcracks are present in sandstones, the velocity ratio usually increases as differential pressure increases. This implies that this theory is optimal for sandstones having intergranular porosities. Even though the accurate behavior of the consolidation parameter with respect to differential pressure or the degree of consolidation is not known, this theory presents a new way to predict S-wave velocity from P-wave velocity and porosity and to calculate elastic velocities of gas-hydrate-bearing sediments. For given properties of sandstones such as bulk and shear moduli of matrix, only the consolidation parameter affects velocities, and this parameter can be estimated directly from the measurements; thus, the prediction of S-wave velocity is accurate, reflecting in-place conditions.

Differential-optoacoustic absorption detector

NASA Technical Reports Server (NTRS)

Shumate, M. S.

1977-01-01

Two-cell spectrophone detects trace amounts of atmospheric pollutants by measuring absorption coefficients of gases with various laser sources. Device measures pressure difference between two tapered cells with differential manometer. Background signal is reduced by balanced window heating and balanced carrier gas absorption in two cells.

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.

Intermittent midline suprasternal neck mass caused by superior herniation of the thymus.

PubMed

Su, Siew Choo; Hess, Thomas; Whybourne, Annie; Chang, Anne B

2015-03-01

Neck masses in infants and children have a wide differential diagnosis. However, neck masses apparent only during raised intrathoracic pressure are rare with a limited number of causes, including superior herniation of the normal thymus, apical lung herniation, jugular phlebectasia and laryngocoele. These conditions can easily be differentiated from one another by imaging. We present an infant with intermittent suprasternal neck mass visible only during increased intrathoracic pressure, produced either by crying or straining. Diagnosis of superior herniation of the thymus into the neck was confirmed by ultrasonography with the characteristic sonographic appearances of the normal thymus as well as its shape, size and location. Ultrasonography should be the first imaging modality of choice. Management of superior herniation of the thymus into the neck should be conservative as the thymus naturally involutes with increasing age. Awareness of the differential diagnosis of neck swelling present only on Vasalva manoeuvre or increased intrathoracic pressure is important to prevent unnecessary tests, avoid radiation, biopsy and surgery. © 2014 The Authors. Journal of Paediatrics and Child Health © 2014 Paediatrics and Child Health Division (Royal Australasian College of Physicians).

Optimization of differentiation time of mesenchymal-stem-cell to tenocyte under a cyclic stretching with a microgrooved culture membrane and selected measurement cells.

PubMed

Morita, Yasuyuki; Yamashita, Takahiro; Toku, Toku; Ju, Yang

2018-01-01

There is a need for efficient stem cell-to-tenocyte differentiation techniques for tendon tissue engineering. More than 1 week is required for tenogenic differentiation with chemical stimuli, including co-culturing. Research has begun to examine the utility of mechanical stimuli, which reduces the differentiation time to several days. However, the precise length of time required to differentiate human bone marrow-derived mesenchymal stem cells (hBMSCs) into tenocytes has not been clarified. Understanding the precise time required is important for future tissue engineering projects. Therefore, in this study, a method was developed to more precisely determine the length of time required to differentiate hBMSCs into tenocytes with cyclic stretching stimulus. First, it had to be determined how stretching stimulation affected the cells. Microgrooved culture membranes were used to suppress cell orientation behavior. Then, only cells oriented parallel to the microgrooves were selected and evaluated for protein synthesis levels for differentiation. The results revealed that growing cells on the microgrooved membrane and selecting optimally-oriented cells for measurement improved the accuracy of the differentiation evaluation, and that hBMSCs differentiated into tenocytes in approximately 10 h. The differentiation time corresponded to the time required for cellular cytoskeleton reorganization and cellular morphology alterations. This suggests that cells, when subjected to mechanical stimulus, secrete mRNAs and proteins for both cytoskeleton reorganization and differentiation.

Static strength of molybdenum to 92 GPa under radial X-ray diffraction

NASA Astrophysics Data System (ADS)

Xiong, L.; Tu, P.; Li, B.; Wu, S. Y.; Hao, J. B.; Bai, L. G.; Li, X. D.; Liu, J.

2018-06-01

The high-pressure strength of molybdenum (Mo) to 92 GPa has been studied by radial X-ray diffraction (RXRD) technique. The ratio of t/G is found to decrease above ˜24 GPa, showing the yield of Mo which is caused by plastic deformation at this pressure. Combined with high-pressure shear modulus, it was found that the differential stress corresponding to the yield of Mo at 24 GPa due to plastic deformation is 1.73 GPa. The second increase of t values occurs after ˜66 GPa, suggesting the strength of Mo with a differential stress of ˜1.93 GPa. In addition, the maximum difference stress of molybdenum at 87 GPa is 3.01 GPa.

A method for measuring the local gas pressure within a gas-flow stage in situ in the transmission electron microscope

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

Colby, Robert J.; Alsem, Daan H.; Liyu, Andrey V.

2015-06-01

The development of environmental transmission electron microscopy (TEM) has enabled in situ experiments in a gaseous environment with high resolution imaging and spectroscopy. Addressing scientific challenges in areas such as catalysis, corrosion, and geochemistry can require pressures much higher than the ~20 mbar achievable with a differentially pumped, dedicated environmental TEM. Gas flow stages, in which the environment is contained between two semi-transparent thin membrane windows, have been demonstrated at pressures of several atmospheres. While this constitutes significant progress towards operando measurements, the design of many current gas flow stages is such that the pressure at the sample cannot necessarilymore » be directly inferred from the pressure differential across the system. Small differences in the setup and design of the gas flow stage can lead to very different sample pressures. We demonstrate a method for measuring the gas pressure directly, using a combination of electron energy loss spectroscopy and TEM imaging. This method requires only two energy filtered TEM images, limiting the measurement time to a few seconds and can be performed during an ongoing experiment at the region of interest. This approach provides a means to ensure reproducibility between different experiments, and even between very differently designed gas flow stages.« less

Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

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

Hou, X; Hu, YH; Grinthal, A

Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems(1-10). But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries(6,11-17), a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling ismore » nearly inevitable(11,12). Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold-the pressure needed to open the pores-can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas-liquid sorting in a microfluidic flow and to separate a three-phase air-water-oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.« less

Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

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

Hou, Xu; Hu, Yuhang; Grinthal, Alison

Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. In addition, the ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems 1-10.But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries 6,11–17, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect,more » and fouling is nearly inevitable.Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state.Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold—the pressure needed to open the pores—can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping.These capabilities allow us to dynamically modulate gas–liquid sorting in a microfluidic flow and to separate a three-phase air water–oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.« less

Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

NASA Astrophysics Data System (ADS)

Hou, Xu; Hu, Yuhang; Grinthal, Alison; Khan, Mughees; Aizenberg, Joanna

2015-03-01

Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems. But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling is nearly inevitable. Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold--the pressure needed to open the pores--can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas-liquid sorting in a microfluidic flow and to separate a three-phase air-water-oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.

Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour

DOE PAGES

Hou, Xu; Hu, Yuhang; Grinthal, Alison; ...

2015-03-04

Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. In addition, the ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems 1-10.But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries 6,11–17, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect,more » and fouling is nearly inevitable.Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state.Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold—the pressure needed to open the pores—can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping.These capabilities allow us to dynamically modulate gas–liquid sorting in a microfluidic flow and to separate a three-phase air water–oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.« less

Liquid-based gating mechanism with tunable multiphase selectivity and antifouling behaviour.

PubMed

Hou, Xu; Hu, Yuhang; Grinthal, Alison; Khan, Mughees; Aizenberg, Joanna

2015-03-05

Living organisms make extensive use of micro- and nanometre-sized pores as gatekeepers for controlling the movement of fluids, vapours and solids between complex environments. The ability of such pores to coordinate multiphase transport, in a highly selective and subtly triggered fashion and without clogging, has inspired interest in synthetic gated pores for applications ranging from fluid processing to 3D printing and lab-on-chip systems. But although specific gating and transport behaviours have been realized by precisely tailoring pore surface chemistries and pore geometries, a single system capable of controlling complex, selective multiphase transport has remained a distant prospect, and fouling is nearly inevitable. Here we introduce a gating mechanism that uses a capillary-stabilized liquid as a reversible, reconfigurable gate that fills and seals pores in the closed state, and creates a non-fouling, liquid-lined pore in the open state. Theoretical modelling and experiments demonstrate that for each transport substance, the gating threshold-the pressure needed to open the pores-can be rationally tuned over a wide pressure range. This enables us to realize in one system differential response profiles for a variety of liquids and gases, even letting liquids flow through the pore while preventing gas from escaping. These capabilities allow us to dynamically modulate gas-liquid sorting in a microfluidic flow and to separate a three-phase air-water-oil mixture, with the liquid lining ensuring sustained antifouling behaviour. Because the liquid gating strategy enables efficient long-term operation and can be applied to a variety of pore structures and membrane materials, and to micro- as well as macroscale fluid systems, we expect it to prove useful in a wide range of applications.

A Darwinian approach to the origin of life cycles with group properties.

PubMed

Rashidi, Armin; Shelton, Deborah E; Michod, Richard E

2015-06-01

A selective explanation for the evolution of multicellular organisms from unicellular ones requires knowledge of both selective pressures and factors affecting the response to selection. Understanding the response to selection is particularly challenging in the case of evolutionary transitions in individuality, because these transitions involve a shift in the very units of selection. We develop a conceptual framework in which three fundamental processes (growth, division, and splitting) are the scaffold for unicellular and multicellular life cycles alike. We (i) enumerate the possible ways in which these processes can be linked to create more complex life cycles, (ii) introduce three genes based on growth, division and splitting that, acting in concert, determine the architecture of the life cycles, and finally, (iii) study the evolution of the simplest five life cycles using a heuristic model of coupled ordinary differential equations in which mutations are allowed in the three genes. We demonstrate how changes in the regulation of three fundamental aspects of colonial form (cell size, colony size, and colony cell number) could lead unicellular life cycles to evolve into primitive multicellular life cycles with group properties. One interesting prediction of the model is that selection generally favors cycles with group level properties when intermediate body size is associated with lowest mortality. That is, a universal requirement for the evolution of group cycles in the model is that the size-mortality curve be U-shaped. Furthermore, growth must decelerate with size. Copyright © 2015 Elsevier Inc. All rights reserved.

Static Feed Water Electrolysis Subsystem Testing and Component Development

NASA Technical Reports Server (NTRS)

Koszenski, E. P.; Schubert, F. H.; Burke, K. A.

1983-01-01

A program was carried out to develop and test advanced electrochemical cells/modules and critical electromechanical components for a static feed (alkaline electrolyte) water electrolysis oxygen generation subsystem. The accomplishments were refurbishment of a previously developed subsystem and successful demonstration for a total of 2980 hours of normal operation; achievement of sustained one-person level oxygen generation performance with state-of-the-art cell voltages averaging 1.61 V at 191 ASF for an operating temperature of 128F (equivalent to 1.51V when normalized to 180F); endurance testing and demonstration of reliable performance of the three-fluid pressure controller for 8650 hours; design and development of a fluid control assembly for this subsystem and demonstration of its performance; development and demonstration at the single cell and module levels of a unitized core composite cell that provides expanded differential pressure tolerance capability; fabrication and evaluation of a feed water electrolyte elimination five-cell module; and successful demonstration of an electrolysis module pressurization technique that can be used in place of nitrogen gas during the standby mode of operation to maintain system pressure and differential pressures.

Leak test fixture and method for using same

DOEpatents

Hawk, Lawrence S.

1976-01-01

A method and apparatus are provided which are especially useful for leak testing seams such as an end closure or joint in an article. The test does not require an enclosed pressurized volume within the article or joint section to be leak checked. A flexible impervious membrane is disposed over an area of the seamed surfaces to be leak checked and sealed around the outer edges. A preselected vacuum is applied through an opening in the membrane to evacuate the area between the membrane and the surface being leak checked to essentially collapse the membrane to conform to the article surface or joined adjacent surfaces. A pressure differential is concentrated at the seam bounded by the membrane and only the seam experiences a pressure differential as air or helium molecules are drawn into the vacuum system through a leak in the seam. A helium detector may be placed in a vacuum exhaust line from the membrane to detect the helium. Alternatively, the vacuum system may be isolated at a preselected pressure and leaks may be detected by a subsequent pressure increase in the vacuum system.

Analytic Formulation and Numerical Implementation of an Acoustic Pressure Gradient Prediction

NASA Technical Reports Server (NTRS)

Lee, Seongkyu; Brentner, Kenneth S.; Farassat, Fereidoun

2007-01-01

The scattering of rotor noise is an area that has received little attention over the years, yet the limited work that has been done has shown that both the directivity and intensity of the acoustic field may be significantly modified by the presence of scattering bodies. One of the inputs needed to compute the scattered acoustic field is the acoustic pressure gradient on a scattering surface. Two new analytical formulations of the acoustic pressure gradient have been developed and implemented in the PSU-WOPWOP rotor noise prediction code. These formulations are presented in this paper. The first formulation is derived by taking the gradient of Farassat's retarded-time Formulation 1A. Although this formulation is relatively simple, it requires numerical time differentiation of the acoustic integrals. In the second formulation, the time differentiation is taken inside the integrals analytically. The acoustic pressure gradient predicted by these new formulations is validated through comparison with the acoustic pressure gradient determined by a purely numerical approach for two model rotors. The agreement between analytic formulations and numerical method is excellent for both stationary and moving observers case.

Control device for prosthetic urinary sphincter cuff

NASA Technical Reports Server (NTRS)

Reinicke, Robert H. (Inventor)

1983-01-01

A device for controlling flow of fluid to and from a resilient inflatable cuff implanted about the urethra to control flow of urine therethrough. The device comprises a flexible bulb reservoir and a control unit that includes a manually operated valve that opens automatically when the bulb is squeezed to force fluid into the cuff for closing the urethra. The control unit also includes a movable valve seat member having a relatively large area exposed to pressure of fluid in a chamber that is connected to the cuff and which moves to a position in which the valve member is unseated by an abutment when fluid pressure in the chamber exceeds a predetermined value to thereby relieve excess fluid pressure in the cuff. The arrangement is such that the valve element is held closed against the seat member by the full differential in fluid pressures acting on both sides of the valve element until the seat member is moved away from the valve element to thus insure positive closing of the valve element until the seat member is moved out of engagement with the valve element by excess pressure differential.

Water temperature, not fish morph, determines parasite infections of sympatric Icelandic threespine sticklebacks (Gasterosteus aculeatus)

PubMed Central

Karvonen, Anssi; Kristjánsson, Bjarni K; Skúlason, Skúli; Lanki, Maiju; Rellstab, Christian; Jokela, Jukka

2013-01-01

Parasite communities of fishes are known to respond directly to the abiotic environment of the host, for example, to water quality and water temperature. Biotic factors are also important as they affect the exposure profile through heterogeneities in parasite distribution in the environment. Parasites in a particular environment may pose a strong selection on fish. For example, ecological differences in selection by parasites have been hypothesized to facilitate evolutionary differentiation of freshwater fish morphs specializing on different food types. However, as parasites may also respond directly to abiotic environment the parasite risk does not depend only on biotic features of the host environment. It is possible that different morphs experience specific selection gradients by parasites but it is not clear how consistent the selection is when abiotic factors change. We examined parasite pressure in sympatric morphs of threespine stickleback (Gasterosteus aculeatus) across a temperature gradient in two large Icelandic lakes, Myvatn and Thingvallavatn. Habitat-specific temperature gradients in these lakes are opposite. Myvatn lava rock morph lives in a warm environment, while the mud morph lives in the cold. In Thingvallavatn, the lava rock morph lives in a cold environment and the mud morph in a warm habitat. We found more parasites in fish living in higher temperature in both lakes, independent of the fish morph, and this pattern was similar for the two dominating parasite taxa, trematodes and cestodes. However, at the same time, we also found higher parasite abundance in a third morph living in deep cold–water habitat in Thingvallavatn compared to the cold-water lava morph, indicating strong effect of habitat-specific biotic factors. Our results suggest complex interactions between water temperature and biotic factors in determining the parasite community structure, a pattern that may have implications for differentiation of stickleback morphs. PMID:23789063

Early Planetary Differentiation: Comparative Planetology

NASA Technical Reports Server (NTRS)

Jones, John H.

2006-01-01

We currently have extensive data for four different terrestrial bodies of the inner solar system: Earth, the Moon, Mars, and the Eucrite Parent Body [EPB]. All formed early cores; but all(?) have mantles with elevated concentrations of highly sidero-phile elements, suggestive of the addition of a late "veneer". Two appear to have undergone extensive differentiation consistent with a global magma ocean. One appears to be inconsistent with a simple model of "low-pressure" chondritic differentiation. Thus, there seems to be no single, simple paradigm for understand-ing early differentiation.

Correction of static pressure on a research aircraft in accelerated flight using differential pressure measurements

NASA Astrophysics Data System (ADS)

Rodi, A. R.; Leon, D. C.

2012-11-01

A method is described that estimates the error in the static pressure measurement on an aircraft from differential pressure measurements on the hemispherical surface of a Rosemount model 858AJ air velocity probe mounted on a boom ahead of the aircraft. The theoretical predictions for how the pressure should vary over the surface of the hemisphere, involving an unknown sensitivity parameter, leads to a set of equations that can be solved for the unknowns - angle of attack, angle of sideslip, dynamic pressure and the error in static pressure - if the sensitivity factor can be determined. The sensitivity factor was determined on the University of Wyoming King Air research aircraft by comparisons with the error measured with a carefully designed sonde towed on connecting tubing behind the aircraft - a trailing cone - and the result was shown to have a precision of about ±10 Pa over a wide range of conditions, including various altitudes, power settings, and gear and flap extensions. Under accelerated flight conditions, geometric altitude data from a combined Global Navigation Satellite System (GNSS) and inertial measurement unit (IMU) system are used to estimate acceleration effects on the error, and the algorithm is shown to predict corrections to a precision of better than ±20 Pa under those conditions. Some limiting factors affecting the precision of static pressure measurement on a research aircraft are discussed.

Microenvironment is involved in cellular response to hydrostatic pressures during chondrogenesis of mesenchymal stem cells.

PubMed

Ye, Rui; Hao, Jin; Song, Jinlin; Zhao, Zhihe; Fang, Shanbao; Wang, Yating; Li, Juan

2014-06-01

Chondrocytes integrate numerous microenvironmental cues to mount physiologically relevant differentiation responses, and the regulation of mechanical signaling in chondrogenic differentiation is now coming into intensive focus. To facilitate tissue-engineered chondrogenesis by mechanical strategy, a thorough understanding about the interactional roles of chemical factors under mechanical stimuli in regulating chondrogenesis is in great need. Therefore, this study attempts to investigate the interaction of rat MSCs with their microenvironment by imposing dynamic and static hydrostatic pressure through modulating gaseous tension above the culture medium. Under dynamic pressure, chemical parameters (pH, pO2, and pCO2) were kept in homeostasis. In contrast, pH was remarkably reduced due to increased pCO2 under static pressure. MSCs under the dynamically pressured microenvironment exhibited a strong accumulation of GAG within and outside the alginate beads, while cells under the statically pressured environment lost newly synthesized GAG into the medium with a speed higher than its production. In addition, the synergic influence on expression of chondrogenic genes was more persistent under dynamic pressure than that under static pressure. This temporal contrast was similar to that of activation of endogenous TGF-β1. Taken altogether, it indicates that a loading strategy which can keep a homeostatic chemical microenvironment is preferred, since it might sustain the stimulatory effects of mechanical stimuli on chondrogenesis via activation of endogenous TGF-β1. © 2013 Wiley Periodicals, Inc.

Operationalizing the Rubric: The Effect of Benchmark Selection on the Assessed Quality of Writing.

ERIC Educational Resources Information Center

Popp, Sharon E. Osborn; Ryan, Joseph M.; Thompson, Marilyn S.; Behrens, John T.

The purposes of this study were to investigate the role of benchmark writing samples in direct assessment of writing and to examine the consequences of differential benchmark selection with a common writing rubric. The influences of discourse and grade level were also examined within the context of differential benchmark selection. Raters scored…

On the anomaly of velocity-pressure decoupling in collocated mesh solutions

NASA Technical Reports Server (NTRS)

Kim, Sang-Wook; Vanoverbeke, Thomas

1991-01-01

The use of various pressure correction algorithms originally developed for fully staggered meshes can yield a velocity-pressure decoupled solution for collocated meshes. The mechanism that causes velocity-pressure decoupling is identified. It is shown that the use of a partial differential equation for the incremental pressure eliminates such a mechanism and yields a velocity-pressure coupled solution. Example flows considered are a three dimensional lid-driven cavity flow and a laminar flow through a 90 deg bend square duct. Numerical results obtained using the collocated mesh are in good agreement with the measured data and other numerical results.

Transcriptional profiling identifies differentially expressed genes in developing turkey skeletal muscle

PubMed Central

2011-01-01

Background Skeletal muscle growth and development from embryo to adult consists of a series of carefully regulated changes in gene expression. Understanding these developmental changes in agriculturally important species is essential to the production of high quality meat products. For example, consumer demand for lean, inexpensive meat products has driven the turkey industry to unprecedented production through intensive genetic selection. However, achievements of increased body weight and muscle mass have been countered by an increased incidence of myopathies and meat quality defects. In a previous study, we developed and validated a turkey skeletal muscle-specific microarray as a tool for functional genomics studies. The goals of the current study were to utilize this microarray to elucidate functional pathways of genes responsible for key events in turkey skeletal muscle development and to compare differences in gene expression between two genetic lines of turkeys. To achieve these goals, skeletal muscle samples were collected at three critical stages in muscle development: 18d embryo (hyperplasia), 1d post-hatch (shift from myoblast-mediated growth to satellite cell-modulated growth by hypertrophy), and 16wk (market age) from two genetic lines: a randombred control line (RBC2) maintained without selection pressure, and a line (F) selected from the RBC2 line for increased 16wk body weight. Array hybridizations were performed in two experiments: Experiment 1 directly compared the developmental stages within genetic line, while Experiment 2 directly compared the two lines within each developmental stage. Results A total of 3474 genes were differentially expressed (false discovery rate; FDR < 0.001) by overall effect of development, while 16 genes were differentially expressed (FDR < 0.10) by overall effect of genetic line. Ingenuity Pathways Analysis was used to group annotated genes into networks, functions, and canonical pathways. The expression of 28 genes involved in extracellular matrix regulation, cell death/apoptosis, and calcium signaling/muscle function, as well as genes with miscellaneous function was confirmed by qPCR. Conclusions The current study identified gene pathways and uncovered novel genes important in turkey muscle growth and development. Future experiments will focus further on several of these candidate genes and the expression and mechanism of action of their protein products. PMID:21385442

Numerical and experimental simulation of the mechanical behavior of super-pressure balloon subsystems

NASA Astrophysics Data System (ADS)

Siguier, J.; Guigue, P.; Karama, M.; Mistou, S.; Dalverny, O.; Granier, S.

Long duration super-pressure balloons are a great challenge in scientific ballooning. Whatever the balloon type considered (spherical, pumpkin,...), it is necessary to have good knowledge of the mechanical behavior of the envelope regarding the flight level and the life-span of the balloon. For this reason CNES, ONERA and ENIT are carrying out a research program of modelization and experimentation in order to predict the envelope shape of a balloon in different conditions of temperature and differential pressure. On the one hand, we define the mechanical laws of envelope materials, that is the elasticity, plasticity and viscosity properties of polymers, and find the parameters of the law with unidirectional tests. These laws are introduced in a finite element code which predict the stress and strain state of a complex envelope structure. On the other hand, we are developing an experimental set-up to measure the 3D strain of a balloon sub-system, that is including the envelope, assemblies and apex parts, with realistic flight conditions. This facility, called NIRVANA, is a 1m3 vacuum chamber with cooled screens equipped with a stereoscopic CCD measurement system. We can submit a 1,5m diameter sample to differential pressure, regulate the temperature from +20°C to -120°C and apply a load to tendons of up to 6 tons if required. This paper presents the first results of the modelizations and m asurements of ane envelope sample submitted to axisymetrical stress due to the differential pressure. This sample consists of a 50μm multi-layer polymer film with an assembly, used in 10m diameter STRATEOLE super-pressure balloons. The modelization gives results which largely agree with the experiment and enable us to continue with cold conditions and more complex structures.

Numerical and experimental simulation of the mechanical behavior of super-pressure balloon subsystems

NASA Astrophysics Data System (ADS)

Siguier, J.-M.; Guigue, P.; Karama, M.; Mistou, S.; Dalverny, O.; Granier, S.

2004-01-01

Long duration super-pressure balloons constitute a great challenge in scientific ballooning. For any type of balloons (spherical, pumpkin, …), it is necessary to have a good knowledge of the mechanical behavior of envelopes regarding the level and the lifetime of the flight. For this reason CNES, ONERA and ENIT are carrying out a research program of modelization and experimentation in order to predict the envelope shape of a balloon in different conditions of temperature and differential pressure. This study was conducted in two parts. During the first one, we defined, with parameters obtained from unidirectional tests, the mechanical laws (elasticity, plasticity and viscosity properties of polymers) of materials involved in the envelope. These laws are introduced in a finite element code, which predicts the stress and strain status of a complex envelope structure. During the second one, we developed an experimental set-up to measure the 3D strain on a balloon subsystem, which includes envelope, assemblies and apex parts, in real flight conditions. This facility, called NIRVANA, is a 1 m 3 vacuum chamber with cooled screens equipped with a stereoscopic CCD measurement system. A 1.5 m diameter sample can be tested under differential pressure, regulated temperature (from +20 to -120 °C) and a load (up to 6 tonnes) applied on tendons. This paper presents the first results obtained from the modelizations and measurements done on an envelope sample submitted to axisymmetrical stress due to the differential pressure. This sample consists of a 50 μm multilayer polymer film with an assembly, used in 10 m diameter STRATEOLE super-pressure balloons. The modelization gives results in good accordance with the experiments and will enable us to follow this work with cold conditions, time dependence (creeping) and more complex structures.

Differential Systolic and Diastolic Regulation of the Cerebral Pressure-Flow Relationship During Squat-Stand Manoeuvres.

PubMed

Smirl, Jonathan D; Wright, Alexander D; Ainslie, Philip N; Tzeng, Yu-Chieh; van Donkelaar, Paul

2018-01-01

Cerebral pressure-flow dynamics are typically reported between mean arterial pressure and mean cerebral blood velocity. However, by reporting only mean responses, potential differential regulatory properties associated with systole and diastole may have been overlooked. Twenty young adults (16 male, age: 26.7 ± 6.6 years, BMI: 24.9 ± 3.0 kg/m 2 ) were recruited for this study. Middle cerebral artery velocity was indexed via transcranial Doppler. Cerebral pressure-flow dynamics were assessed using transfer function analysis at both 0.05 and 0.10 Hz using squat-stand manoeuvres. This method provides robust and reliable measures for coherence (correlation index), phase (timing buffer) and gain (amplitude buffer) metrics. There were main effects for both cardiac cycle and frequency for phase and gain metrics (p < 0.001). The systolic phase (mean ± SD) was elevated at 0.05 (1.07 ± 0.51 radians) and 0.10 Hz (0.70 ± 0.46 radians) compared to the diastolic phase (0.05 Hz: 0.59 ± 0.14 radians; 0.10 Hz: 0.33 ± 0.11 radians). Conversely, the systolic normalized gain was reduced (0.05 Hz: 0.49 ± 0.12%/%; 0.10 Hz: 0.66 ± 0.20%/%) compared to the diastolic normalized gain (0.05 Hz: 1.46 ± 0.43%/%; 0.10 Hz: 1.97 ± 0.48%/%). These findings indicate there are differential systolic and diastolic aspects of the cerebral pressure-flow relationship. The oscillations associated with systole are extensively buffered within the cerebrovasculature, whereas diastolic oscillations are relatively unaltered. This indicates that the brain is adapted to protect itself against large increases in systolic blood pressure, likely as a mechanism to prevent cerebral haemorrhages.

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

Genetic diversity and structure of the threatened species Sinopodophyllum hexandrum (Royle) Ying.

PubMed

Liu, W; Wang, J; Yin, D X; Yang, M; Wang, P; Han, Q S; Ma, Q Q; Liu, J J; Wang, J X

2016-06-10

Sinopodophyllum hexandrum is an important medicinal plant that has been listed as an endangered species, making the conservation of its genetic diversity a priority. Therefore, the genetic diversity and population structure of S. hexandrum was investigated through inter-simple sequence repeat analysis of eight natural populations. Eleven selected primers generated 141 discernible fragments. The percentage of polymorphic bands was 37.59% at the species level, and 7.66-24.32% at the population level. Genetic diversity of S. hexandrum was low within populations (average HE = 0.0366), but higher at the species level (HE = 0.0963). Clear structure and high genetic differentiation were detected between populations using unweighted pair groups mean arithmetic and principle coordinate analysis. Clustering approaches clustered the eight sampled populations into three major groups, and AMOVA confirmed there to be significant variation between populations (63.27%). Genetic differentiation may have arisen through limited gene flow (Nm = 0.3317) in this species. Isolation by distance among populations was determined by comparing genetic distance versus geographical distance using the Mantel test. The results revealed no correlation between spatial pattern and geographic location. Given the low within-population genetic diversity, high differentiation among populations, and the increasing anthropogenic pressure on this species, in situ conservation measures, in addition to sampling and ex situ preservation, are recommended to preserve S. hexandrum populations and to retain their genetic diversity.

Differential foraging preferences on seed size by rodents result in higher dispersal success of medium-sized seeds.

PubMed

Cao, Lin; Wang, Zhenyu; Yan, Chuan; Chen, Jin; Guo, Cong; Zhang, Zhibin

2016-11-01

Rodent preference for scatter-hoarding large seeds has been widely considered to favor the evolution of large seeds. Previous studies supporting this conclusion were primarily based on observations at earlier stages of seed dispersal, or on a limited sample of successfully established seedlings. Because seed dispersal comprises multiple dispersal stages, we hypothesized that differential foraging preference on seed size by animal dispersers at different dispersal stages would ultimately result in medium-sized seeds having the highest dispersal success rates. In this study, by tracking a large number of seeds for 5 yr, we investigated the effects of seed size on seed fates from seed removal to seedling establishment of a dominant plant Pittosporopsis kerrii (Icacinaceae) dispersed by scatter-hoarding rodents in tropical forest in southwest China. We found that small seeds had a lower survival rate at the early dispersal stage where more small seeds were predated at seed stations and after removal; large seeds had a lower survival rate at the late dispersal stage, more large seeds were recovered, predated after being cached, or larder-hoarded. Medium-sized seeds experienced the highest dispersal success. Our study suggests that differential foraging preferences by scatter-hoarding rodents at different stages of seed dispersal could result in conflicting selective pressures on seed size and higher dispersal success of medium-sized seeds. © 2016 by the Ecological Society of America.

Multiphase flow calculation software

DOEpatents

Fincke, James R.

2003-04-15

Multiphase flow calculation software and computer-readable media carrying computer executable instructions for calculating liquid and gas phase mass flow rates of high void fraction multiphase flows. The multiphase flow calculation software employs various given, or experimentally determined, parameters in conjunction with a plurality of pressure differentials of a multiphase flow, preferably supplied by a differential pressure flowmeter or the like, to determine liquid and gas phase mass flow rates of the high void fraction multiphase flows. Embodiments of the multiphase flow calculation software are suitable for use in a variety of applications, including real-time management and control of an object system.

Pressure Measurements Using an Airborne Differential Absorption Lidar. Part 1; Analysis of the Systematic Error Sources

NASA Technical Reports Server (NTRS)

Flamant, Cyrille N.; Schwemmer, Geary K.; Korb, C. Laurence; Evans, Keith D.; Palm, Stephen P.

1999-01-01

Remote airborne measurements of the vertical and horizontal structure of the atmospheric pressure field in the lower troposphere are made with an oxygen differential absorption lidar (DIAL). A detailed analysis of this measurement technique is provided which includes corrections for imprecise knowledge of the detector background level, the oxygen absorption fine parameters, and variations in the laser output energy. In addition, we analyze other possible sources of systematic errors including spectral effects related to aerosol and molecular scattering interference by rotational Raman scattering and interference by isotopic oxygen fines.

Activation of TRPV2 negatively regulates the differentiation of mouse brown adipocytes.

PubMed

Sun, Wuping; Uchida, Kunitoshi; Takahashi, Nobuyuki; Iwata, Yuko; Wakabayashi, Shigeo; Goto, Tsuyoshi; Kawada, Teruo; Tominaga, Makoto

2016-09-01

Transient receptor potential vanilloid 2 (TRPV2) acts as a Ca(2+)-permeable non-selective cation channel that has been reported to be sensitive to temperature, mechanical force, and some chemicals. We recently showed that TRPV2 is critical for maintenance of the thermogenic function of brown adipose tissue in mice. However, the involvement of TRPV2 in the differentiation of brown adipocytes remains unexplored. We found that the expression of TRPV2 was dramatically increased during the differentiation of brown adipocytes. Non-selective TRPV2 agonists (2-aminoethoxydiphenyl borate and lysophosphatidylcholine) inhibited the differentiation of brown adipocytes in a dose-dependent manner during the early stage of differentiation of brown adipocytes. The inhibition was rescued by a TRPV2-selective antagonist, SKF96365 (SKF). Mechanical force, which activates TRPV2, also inhibited the differentiation of brown adipocytes in a strength-dependent manner, and the effect was reversed by SKF. In addition, the inhibition of adipocyte differentiation by either TRPV2 ligand or mechanical stimulation was significantly smaller in the cells from TRPV2KO mice. Moreover, calcineurin inhibitors, cyclosporine A and FK506, partially reversed TRPV2 activation-induced inhibition of brown adipocyte differentiation. Thus, we conclude that TRPV2 might be involved in the modulation of brown adipocyte differentiation partially via a calcineurin pathway.

Properties of meso-Erythritol; phase state, accommodation coefficient and saturation vapour pressure

NASA Astrophysics Data System (ADS)

Emanuelsson, Eva; Tschiskale, Morten; Bilde, Merete

2016-04-01

Introduction Saturation vapour pressure and the associated temperature dependence (enthalpy ΔH), are key parameters for improving predictive atmospheric models. Generally, the atmospheric aerosol community lack experimentally determined values of these properties for relevant organic aerosol compounds (Bilde et al., 2015). In this work we have studied the organic aerosol component meso-Erythritol. Methods Sub-micron airborne particles of meso-Erythritol were generated by nebulization from aqueous solution, dried, and a mono disperse fraction of the aerosol was selected using a differential mobility analyser. The particles were then allowed to evaporate in the ARAGORN (AaRhus Atmospheric Gas phase OR Nano particle) flow tube. It is a temperature controlled 3.5 m long stainless steel tube with an internal diameter of 0.026 m (Bilde et al., 2003, Zardini et al., 2010). Changes in particle size as function of evaporation time were determined using a scanning mobility particle sizer system. Physical properties like air flow, temperature, humidity and pressure were controlled and monitored on several places in the setup. The saturation vapour pressures were then inferred from the experimental results in the MATLAB® program AU_VaPCaP (Aarhus University_Vapour Pressure Calculation Program). Results Following evaporation, meso-Erythriol under some conditions showed a bimodal particle size distribution indicating the formation of particles of two different phase states. The issue of physical phase state, along with critical assumptions e.g. the accommodation coefficient in the calculations of saturation vapour pressures of atmospheric relevant compounds, will be discussed. Saturation vapour pressures from the organic compound meso-Erythritol will be presented at temperatures between 278 and 308 K, and results will be discussed in the context of atmospheric chemistry. References Bilde, M. et al., (2015), Chemical Reviews, 115 (10), 4115-4156. Bilde, M. et. al., (2003), Environmental Science and Technology 37(7), 1371-1378. Zardini, A. A. et al., (2010), Journal of Aerosol Science, 41, 760-770.

A simulation-based study on different control strategies for variable speed pump in distributed ground source heat pump systems

DOE PAGES

Liu, Xiaobing; Zheng, O'Neill; Niu, Fuxin

2016-01-01

Most commercial ground source heat pump systems (GSHP) in the United States are in a distributed configuration. These systems circulate water or an anti-freeze solution through multiple heat pump units via a central pumping system, which usually uses variable speed pump(s). Variable speed pumps have potential to significantly reduce pumping energy use; however, the energy savings in reality could be far away from its potential due to improper pumping system design and controls. In this paper, a simplified hydronic pumping system was simulated with the dynamic Modelica models to evaluate three different pumping control strategies. This includes two conventional controlmore » strategies, which are to maintain a constant differential pressure across either the supply and return mains, or at the most hydraulically remote heat pump; and an innovative control strategy, which adjusts system flow rate based on the demand of each heat pump. The simulation results indicate that a significant overflow occurs at part load conditions when the variable speed pump is controlled to main a constant differential pressure across the supply and return mains of the piping system. On the other hand, an underflow occurs at part load conditions when the variable speed pump is controlled to maintain a constant differential pressure across the furthest heat pump. The flow-demand-based control can provide needed flow rate to each heat pump at any given time, and with less pumping energy use than the two conventional controls. Finally, a typical distributed GSHP system was studied to evaluate the energy saving potential of applying the flow-demand-based pumping control strategy. This case study shows that the annual pumping energy consumption can be reduced by 62% using the flow-demand-based control compared with that using the conventional pressure-based control to maintain a constant differential pressure a cross the supply and return mains.« less

Selection of Soybean Pods by the Stink Bugs, Nezara viridula and Piezodorus guildinii

PubMed Central

Molina, Gonzalo A. R.; Trumper, Eduardo V.

2012-01-01

Different biological parameters of the stink bugs, Nezara viridula L. and Piezodorus guildinii Westwood (Hemiptera: Pentatomidae), are affected by the developmental stage of the soybean (Glycine max Merrill) pods they feed on. These effects of the soybean on the stink bugs could represent a selection pressure leading to the ability of these species to discriminate the phenological stage of soybean pods, and, therefore, to exhibit feeding preferences. We designed three studies: (1) Distant detection of soybean pods through an olfactometer; (2) Free choice tests to evaluate preferences for soybean pods of different developmental stages; (3) No choice tests to study effects of soybean pod development on feeding time and number of probes. Stink bugs showed no differential response to olfactometer arms with or without soybean pods, suggesting an inability to detect soybean volatiles. Free choice tests showed no species effects on pods selection, but significant differences among fifth instar nymphs, adult male, and adult females. Fifth instar nymphs fed more frequently on soybean pods of advanced development stages compared to female adults, despite previous evidence showing poor development of stink bugs fed pods of the same stage. No choice tests showed significant effects of stink bug species, stink bug stage and sex, and soybean pod phenology. N. viridula expressed shorter feeding times and higher numbers of probes than P. guildinii. The highest numbers of probes of both species were observed when they were fed soybean pods in early phenological stages. When placed in direct contact with food, fifth instar nymphs prefered to feed on more developed pods, despite these pods being suboptimal food items. These results suggest that for the ecological time framework of soybean-stink bugs coexistence, around thirty-five years in Argentina, the selection pressure was not enough for stink bugs to evolve food preferences that match their performance on soybean pods of different development stages. PMID:23437991

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..

Allergenic properties and differential response of walnut subjected to processing treatments

USDA-ARS?s Scientific Manuscript database

Walnut is one of the most frequently involved foods in anaphylactic reactions. We investigated changes in walnut allergenicity after physical treatments by in vitro techniques and physiologically relevant assays. Changes in the allergenicity of walnut subjected to high pressure and thermal/pressur...

Formation of porous HPCL/LPCL/HA scaffolds with supercritical CO2 gas foaming method.

PubMed

Moghadam, M Zahedi; Hassanajili, Sh; Esmaeilzadeh, F; Ayatollahi, M; Ahmadi, M

2017-05-01

Scaffold is a 3D porous structure that is made of different materials, such as synthetic and natural polymers. It plays the role of a synthetic extracellular matrix and permits adhesion, proliferation and differentiation of the cells. Porosity and pore size are the important factors for any 3D scaffold used in bone tissue engineering. In this study, porous scaffolds were prepared by adding hydroxyapatite (HA) nanoparticles as filler to the polymeric matrix of polycaprolactone (PCL) blends with two different molecular weight by using supercritical CO 2 (ScCO 2 ) foaming method. The effect of different parameters such as CO 2 pressure, ratios of the polymers and amount of the filler on the scaffold properties was investigated. The results showed that porosity increased with increment of pressure and decreased with increasing the ratio of the high molecular weight PCL to the low molecular weight PCL in the scaffolds and also HA content. Optimum condition for obtaining adequate porous scaffold of HPCL/LPCL/HA occurred at 140bar and 45°C. The physical and mechanical properties of the prepared scaffolds were characterized using DSC, XRD, FTIR, SEM, contact angle and compression test. By analyzing the results of these tests, optimum sample for cell culture was selected. The biocompatibility of the selected HPCL/LPCL/HA scaffold (HPCL/LPCL 60/40 containing 2.5% HA) was assessed in vitro by using human mesenchymal stem cells (hMSCs). Copyright © 2016 Elsevier Ltd. All rights reserved.

Suitability of polymer materials for production of pulmonary microparticles using a PGSS supercritical fluid technique: thermodynamic behaviour of fatty acids, PEGs and PEG-fatty acids.

PubMed

Vijayaraghavan, Meera; Stolnik, Snjezana; Howdle, Steven M; Illum, Lisbeth

2012-11-15

The thermodynamic behaviour of selected polymeric components for preparation of controlled release microparticles using supercritical carbon dioxide (scCO(2)) processing was investigated. The polymeric materials selected were egg lecithin (a model for the lung surfactant phospholipid), poly(ethyleneglycol) (PEG) of different molecular weights, fatty acids (C18, C16, and C14), and physical blends of PEGs and fatty acids. In addition a range of PEG-stearates was also assessed. Analysis of thermodynamic behaviour was performed by differential scanning calorimetry (DSC) and by assessment of their interaction with scCO(2) in a high-pressure variable volume view cell. The key criterion was to demonstrate a strong interaction with scCO(2) and to show liquefaction of the polymeric material at acceptable processing temperatures and pressures. Positive results should then indicate the suitability of these materials for processing by the Particle from Gas Saturated Solutions (PGSS) technique using scCO(2) to create microparticles for pulmonary administration. It was found that the materials tested interacted with scCO(2) and showed a sufficient lowering of their melting temperature (T(m)) to make them suitable for use in the PGSS microparticle production rig. Fatty acids of low T(m) were shown to act as a plasticising agent and to lower the T(m) of PEG further during interaction with scCO(2). Copyright © 2012 Elsevier B.V. All rights reserved.

Flow Field Measurements Using Hotwire Anemometry.

DTIC Science & Technology

1987-09-01

is connected to the differential pressure transducer, the other is connected to an absolute pressure transducer. Static pressure from the absolute ...and intercept data. The seventh variable contains the calibration tunnel temperature in degrees Farenheit . This is0* . used for hotwire compensation...output is then directed to channel five of the Relay Multiplexer. Voltage output from the signal amplifier is zeroed at 0 degrees AOA and is positive for

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.

Hurricane Rita surge data, southwestern Louisiana and southeastern Texas, September to November 2005

USGS Publications Warehouse

McGee, Benton D.; Goree, Burl B.; Tollett, Roland W.; Woodward, Brenda K.; Kress, Wade H.

2006-01-01

Pressure transducers and high-water marks were used to document the inland water levels related to storm surge generated by Hurricane Rita in southwestern Louisiana and southeastern Texas. On September 22-23, 2005, an experimental monitoring network consisting of 47 pressure transducers (sensors) was deployed at 33 sites over an area of about 4,000 square miles to record the timing, extent, and magnitude of inland hurricane storm surge and coastal flooding. Sensors were programmed to record date and time, temperature, and barometric or water pressure. Water pressure was corrected for changes in barometric pressure and salinity. Elevation surveys using global-positioning systems and differential levels were used to relate all storm-surge water-level data, reference marks, benchmarks, sensor measuring points, and high-water marks to the North American Vertical Datum of 1988 (NAVD 88). The resulting data indicated that storm-surge water levels over 14 feet above NAVD 88 occurred at three locations and rates of water-level rise greater than 5 feet per hour occurred at three locations near the Louisiana coast. Quality-assurance measures were used to assess the variability and accuracy of the water-level data recorded by the sensors. Water-level data from sensors were similar to data from co-located sensors, permanent U.S. Geological Survey streamgages, and water-surface elevations performed by field staff. Water-level data from sensors at selected locations were compared to corresponding high-water mark elevations. In general, the water-level data from sensors were similar to elevations of high quality high-water marks, while reporting consistently higher than elevations of lesser quality high-water marks.

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.

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.

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

Self pressuring HTP feed systems

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

Whitehead, J.

1999-10-14

Hydrogen peroxide tanks can be pressurized with decomposed HTP (high test hydrogen peroxide) originating in the tank itself. In rocketry, this offers the advantage of eliminating bulky and heavy inert gas storage. Several prototype self-pressurizing HTP systems have recently been designed and tested. Both a differential piston tank and a small gas-driven pump have been tried to obtain the pressure boost needed for flow through a gas generator and back to the tank. Results include terrestrial maneuvering tests of a prototype microsatellite, including warm gas attitude control jets.

Measuring Viscosities of Gases at Atmospheric Pressure

NASA Technical Reports Server (NTRS)

Singh, Jag J.; Mall, Gerald H.; Hoshang, Chegini

1987-01-01

Variant of general capillary method for measuring viscosities of unknown gases based on use of thermal mass-flowmeter section for direct measurement of pressure drops. In technique, flowmeter serves dual role, providing data for determining volume flow rates and serving as well-characterized capillary-tube section for measurement of differential pressures across it. New method simple, sensitive, and adaptable for absolute or relative viscosity measurements of low-pressure gases. Suited for very complex hydrocarbon mixtures where limitations of classical theory and compositional errors make theoretical calculations less reliable.

Musculoskeletal determinants of pelvic sucker function in Hawaiian stream gobiid fishes: interspecific comparisons and allometric scaling.

PubMed

Maie, Takashi; Schoenfuss, Heiko L; Blob, Richard W

2013-07-01

Gobiid fishes possess a distinctive ventral sucker, formed from fusion of the pelvic fins. This sucker is used to adhere to a wide range of substrates including, in some species, the vertical cliffs of waterfalls that are climbed during upstream migrations. Previous studies of waterfall-climbing goby species have found that pressure differentials and adhesive forces generated by the sucker increase with positive allometry as fish grow in size, despite isometry or negative allometry of sucker area. To produce such scaling patterns for pressure differential and adhesive force, waterfall-climbing gobies might exhibit allometry for other muscular or skeletal components of the pelvic sucker that contribute to its adhesive function. In this study, we used anatomical dissections and modeling to evaluate the potential for allometric growth in the cross-sectional area, effective mechanical advantage (EMA), and force generating capacity of major protractor and retractor muscles of the pelvic sucker (m. protractor ischii and m. retractor ischii) that help to expand the sealed volume of the sucker to produce pressure differentials and adhesive force. We compared patterns for three Hawaiian gobiid species: a nonclimber (Stenogobius hawaiiensis), an ontogenetically limited climber (Awaous guamensis), and a proficient climber (Sicyopterus stimpsoni). Scaling patterns were relatively similar for all three species, typically exhibiting isometric or negatively allometric scaling for the muscles and lever systems examined. Although these scaling patterns do not help to explain the positive allometry of pressure differentials and adhesive force as climbing gobies grow, the best climber among the species we compared, S. stimpsoni, does exhibit the highest calculated estimates of EMA, muscular input force, and output force for pelvic sucker retraction at any body size, potentially facilitating its adhesive ability. Copyright © 2013 Wiley Periodicals, Inc.

Evaluation of a combination of sodium hypochlorite and polyhexamethylene biguanide as an egg wash for red-eared slider turtles (Trachemys scripta elegans) to suppress or eliminate Salmonella organisms on egg surfaces and in hatchlings.

PubMed

Mitchell, Mark A; Adamson, Trinka W; Singleton, Charles B; Roundtree, Marlana K; Bauer, Rudy W; Acierno, Mark J

2007-02-01

To evaluate a combination of 2 nonantibiotic microbicide compounds, sodium hypochlorite (NaOCl) and polyhexamethylene biguanide (PHMB), as a treatment to suppress or eliminate Salmonella spp from red-eared slider (RES) turtle (Trachemys scripta elegans) eggs and hatchlings. 2,738 eggs from 8 turtle farms in Louisiana. Eggs were randomly sorted into 3 or, when sufficient eggs were available, 4 treatment groups as follows: control, pressure-differential egg treatment with NaOCl and gentamicin, NaOCl and PHMB bath treatment, and pressure-differential egg treatment with NaOCl and PHMB. Bacterial cultures were performed from specimens of eggs and hatchlings and evaluated for Salmonella spp. RES turtle eggs treated with NaOCl and PHMB as a bath (odds ratio [OR], 0.2 [95% confidence interval (CI), 0.1 to 0.3]) or as a pressure-differential dip (OR, 0.01 [95% CI, 0.001 to 0.07]) or with gentamicin as a pressure-differential dip (OR, 0.1 [95% CI, 0.06 to 0.2]) were significantly less likely to have Salmonella-positive culture results than control-group eggs. Concern over reptile-associated salmonellosis in children in the United States is so great that federal regulations prohibit the sale of turtles that are < 10.2 cm in length. Currently, turtle farms treat eggs with gentamicin solution. Although this has reduced Salmonella shedding, it has also resulted in antimicrobial resistance. Results of our study indicate that a combination of NaOCl and PHMB may be used to suppress or eliminate Salmonella spp on RES turtle eggs and in hatchlings.

Applications of high pressure differential scanning calorimetry to aviation fuel thermal stability research

NASA Technical Reports Server (NTRS)

Neveu, M. C.; Stocker, D. P.

1985-01-01

High pressure differential scanning calorimetry (DSC) was studied as an alternate method for performing high temperature fuel thermal stability research. The DSC was used to measure the heat of reaction versus temperature of a fuel sample heated at a programmed rate in an oxygen pressurized cell. Pure hydrocarbons and model fuels were studied using typical DSC operating conditions of 600 psig of oxygen and a temperature range from ambient to 500 C. The DSC oxidation onset temperature was determined and was used to rate the fuels on thermal stability. Kinetic rate constants were determined for the global initial oxidation reaction. Fuel deposit formation is measured, and the high temperature volatility of some tetralin deposits is studied by thermogravimetric analysis. Gas chromatography and mass spectrometry are used to study the chemical composition of some DSC stressed fuels.

DSS 13 antenna monitor system. [Deep Space Network

NASA Technical Reports Server (NTRS)

Siev, B.; Bayergo, D.

1979-01-01

The development of a monitor system for the DSS 13 antenna is presented. The system checks for accumulator pressures, differential pressures, wind velocity, power supplies, fluid temperatures, and fluid levels. It was concluded that the system performed properly in high winds and correctly reported all malfunctions.

Differential role of afferent and efferent renal nerves in the maintenance of early- and late-phase Dahl S hypertension

PubMed Central

Foss, Jason D.; Fink, Gregory D.

2015-01-01

Clinical data suggest that renal denervation (RDNX) may be an effective treatment for human hypertension; however, it is unclear whether this therapeutic effect is due to ablation of afferent or efferent renal nerves. We have previously shown that RDNX lowers arterial pressure in hypertensive Dahl salt-sensitive (S) rats to a similar degree observed in clinical trials. In addition, we have recently developed a method for selective ablation of afferent renal nerves (renal-CAP). In the present study, we tested the hypothesis that the antihypertensive effect of RDNX in the Dahl S rat is due to ablation of afferent renal nerves by comparing the effect of complete RDNX to renal-CAP during two phases of hypertension in the Dahl S rat. In the early phase, rats underwent treatment after 3 wk of high-NaCl feeding when mean arterial pressure (MAP) was ∼140 mmHg. In the late phase, rats underwent treatment after 9 wk of high NaCl feeding, when MAP was ∼170 mmHg. RDNX reduced MAP ∼10 mmHg compared with sham surgery in both the early and late phase, whereas renal-CAP had no antihypertensive effect. These results suggest that, in the Dahl S rat, the antihypertensive effect of RDNX is not dependent on pretreatment arterial pressure, nor is it due to ablation of afferent renal nerves. PMID:26661098

Differential equations governing slip-induced pore-pressure fluctuations in a water-saturated granular medium

USGS Publications Warehouse

Iverson, R.M.

1993-01-01

Macroscopic frictional slip in water-saturated granular media occurs commonly during landsliding, surface faulting, and intense bedload transport. A mathematical model of dynamic pore-pressure fluctuations that accompany and influence such sliding is derived here by both inductive and deductive methods. The inductive derivation shows how the governing differential equations represent the physics of the steadily sliding array of cylindrical fiberglass rods investigated experimentally by Iverson and LaHusen (1989). The deductive derivation shows how the same equations result from a novel application of Biot's (1956) dynamic mixture theory to macroscopic deformation. The model consists of two linear differential equations and five initial and boundary conditions that govern solid displacements and pore-water pressures. Solid displacements and water pressures are strongly coupled, in part through a boundary condition that ensures mass conservation during irreversible pore deformation that occurs along the bumpy slip surface. Feedback between this deformation and the pore-pressure field may yield complex system responses. The dual derivations of the model help explicate key assumptions. For example, the model requires that the dimensionless parameter B, defined here through normalization of Biot's equations, is much larger than one. This indicates that solid-fluid coupling forces are dominated by viscous rather than inertial effects. A tabulation of physical and kinematic variables for the rod-array experiments of Iverson and LaHusen and for various geologic phenomena shows that the model assumptions commonly are satisfied. A subsequent paper will describe model tests against experimental data. ?? 1993 International Association for Mathematical Geology.

Gender Gap Linked to Differential Socialization for High-Achieving Senior Mathematics Students.

ERIC Educational Resources Information Center

Campbell, James R.; Beaudry, Jeffrey S.

1998-01-01

Examined whether 11th-grade girls and boys enrolled in advanced mathematics courses nationwide were socialized in similar ways, using Campbell's differential socialization paradigm. Results uncovered a gender gap favoring boys. Self-imposed pressure and persistence had important direct effects on achievement. Self-concept had important direct…

The deprivation syndrome is the driving force of phylogeny, ontogeny and oncogeny.

PubMed

Heininger, K

2001-01-01

Energy is the motor of life. Energy ensures the organism's survival and competitive advantage for reproductive success. For almost 3 billion years, unicellular organisms were the only life form on earth. Competition for limited energy resources and raw materials exerted an incessant selective pressure on organisms. In the adverse environment and due to their 'feast and famine' life style, hardiness to a variety of stressors, particularly to nutrient deprivation, was the selection principle. Both resistance and mutagenic adaptation to stressors were established as survival strategies by means of context-specific processes creating stability or variability of DNA sequence. The conservation of transduction pathways and functional homology of effector molecules clearly bear witness that the principles of life established during prokaryotic and eukaryotic unicellular evolution, although later diversified, have been unshakably cast to persist during metazoan phylogenesis. A wealth of evidence suggests that unicellular organisms evolved the phenomena of differentiation and apoptosis, sexual reproduction, and even aging, as responses to environmental challenges. These evolutionary accomplishments were elaborated from the dichotomous resistance/mutagenesis response and sophisticated the capacity of cells to tune their genetic information to changing environmental conditions. Notably, the social deprivation responses, differentiation and apoptosis, evolved as intercellularly coordinated events: a multitude of differentiation processes were elaborated from sporulation, the prototypic stress resistance response, while apoptosis, contrary to current concepts, is no altruistic cell suicide but was programmed as a mutagenic survival response; this response, however, is socially thwarted leading into mutagenic error catastrophe. In the hybrid differentiation-apoptosis process, cytocide and cannibalism of apoptotic cells thus serve the purpose of fueling the survival of the selfish genes in the differentiating cells. However, successful mutagenesis, although repressed, persisted in the asocial stress response of carcinogenesis as a regression to primitive unicellular behavior following failure of intercellular communication. While somatic mutagenesis was largely prevented, Metazoa elaborated germ cell mutagenesis as an evolutionary vehicle. Genetic competence, a primitive, stress-induced mating behavior, evolved into sexual reproduction which harnessed mutagenesis by subjecting highly mutable germ cells to a rigid viability selection. These processes were programmatically fixed as life- and cell-cycle events but retained their deprivation response phenotypes. Thus, the differentiation-apoptosis tandem evolved as the 'clay' to mold the specialized structures and functions of a multicellular organism while sexual reproduction elaborated the principle of quality-checked mutagenesis to create the immense diversity of Metazoa following the Cambrian explosion. Throughout these events, reactive oxygen and nitrogen species, which are regulated by energy homeostasis, shape the genetic information in a regulated but random, uncoded process providing the fitness-related feedback of phenotype to genotype. The interplay of genes and environment establishes a dynamic stimulus-response feedback cycle which, in animate nature, may be the organizing principle to contrive the reciprocal duality of energy and matter.

Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation.

PubMed

Colautti, Robert I; Lau, Jennifer A

2015-05-01

Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. © 2015 John Wiley & Sons Ltd.

Patterns of insecticide resistance and knock down resistance (kdr) in malaria vectors An. arabiensis, An. coluzzii and An. gambiae from sympatric areas in Senegal.

PubMed

Niang, El Hadji Amadou; Konaté, Lassana; Diallo, Mawlouth; Faye, Ousmane; Dia, Ibrahima

2016-02-05

Malaria vector control in Africa relies on insecticides targeting adult mosquito vectors via insecticide treated nets or indoor residual spraying. Despite the proven efficacy of these strategies, the emergence and rapid rise in insecticide resistance in malaria vectors raises many concerns about their sustainability. Therefore, the monitoring of insecticide resistance is essential for resistance management strategies implementation. We investigated the kdr mutation frequencies in 20 sympatric sites of An. arabiensis Patton, An. coluzzii Coetzee & Wilkerson and An. gambiae Giles and its importance in malaria vector control by evaluating the susceptibility to insecticides in four representative sites in Senegal. Sibling species identification and kdr mutation detection were determined using polymerase chain reaction on mosquitoes collected using pyrethrum sprays collection in 20 sites belonging to two transects with differential insecticide selection pressure. The World Health Organization (WHO) tube test was used to determine phenotypic resistance of An. gambiae s.l. to DDT, deltamethrin, lambdacyholothrin, permethrin, bendiocarb and malathion in four representative sites. The L1014F kdr mutation was widely distributed and was predominant in An. gambiae in comparison to An. arabiensis and An. coluzzii. The bioassay tests showed a general trend with a resistance to DDT and pyrethroids and a susceptibility to organophosphate and carbamate according to WHO thresholds. For deltamethrin and permethrin, the two most used insecticides, no significant difference were observed either between the two transects or between mortality rates suggesting no differential selection pressures on malaria vectors. The study of the KD times showed similar trends as comparable levels of resistance were observed, the effect being more pronounced for permethrin. Our study showed a widespread resistance of malaria vectors to DDT and pyrethroids and a widespread distribution of the 1014F kdr allele. These combined observations could suggest the involvement of the kdr mutation. The existence of other resistance mechanisms could not be ruled out as a proportion of mosquitoes did not harbour the kdr allele whereas the populations were fully resistant. The susceptibility to carbamate and organophosphate could be exploited as alternative for insecticide resistance management.

Differentiating Science Instruction: Secondary science teachers' practices

NASA Astrophysics Data System (ADS)

Maeng, Jennifer L.; Bell, Randy L.

2015-09-01

This descriptive study investigated the implementation practices of secondary science teachers who differentiate instruction. Participants included seven high school science teachers purposefully selected from four different schools located in a mid-Atlantic state. Purposeful selection ensured participants included differentiated instruction (DI) in their lesson implementation. Data included semi-structured interviews and field notes from a minimum of four classroom observations, selected to capture the variety of differentiation strategies employed. These data were analyzed using a constant-comparative approach. Each classroom observation was scored using the validated Differentiated Instruction Implementation Matrix-Modified, which captured both the extent to which critical indicators of DI were present in teachers' instruction and the performance levels at which they engaged in these components of DI. Results indicated participants implemented a variety of differentiation strategies in their classrooms with varying proficiency. Evidence suggested all participants used instructional modifications that required little advance preparation to accommodate differences in students' interests and learning profile. Four of the seven participants implemented more complex instructional strategies that required substantial advance preparation by the teacher. Most significantly, this study provides practical strategies for in-service science teachers beginning to differentiate instruction and recommendations for professional development and preservice science teacher education.

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.

Pressure Seal For Frequently Opened Hatch

NASA Technical Reports Server (NTRS)

Kennedy, Steven E.; Kramer, Joel M.

1994-01-01

Pressure-assisted seal for frequently opened hatch includes two sealing rings retained positively so not pulled out during opening. Seal makes contact with hatch well before hatch starts to squeeze rings extending distance over which seal becomes engaged. Improvements include more-secure mounting, redundancy, and better initial sealing action. Also minimizes loss of gas during closure by deflecting inward and closing gap. This action helps differential pressure to force hatch closed.

Evaluation of handwriting kinematics and pressure for differential diagnosis of Parkinson's disease.

PubMed

Drotár, Peter; Mekyska, Jiří; Rektorová, Irena; Masarová, Lucia; Smékal, Zdeněk; Faundez-Zanuy, Marcos

2016-02-01

We present the PaHaW Parkinson's disease handwriting database, consisting of handwriting samples from Parkinson's disease (PD) patients and healthy controls. Our goal is to show that kinematic features and pressure features in handwriting can be used for the differential diagnosis of PD. The database contains records from 37 PD patients and 38 healthy controls performing eight different handwriting tasks. The tasks include drawing an Archimedean spiral, repetitively writing orthographically simple syllables and words, and writing of a sentence. In addition to the conventional kinematic features related to the dynamics of handwriting, we investigated new pressure features based on the pressure exerted on the writing surface. To discriminate between PD patients and healthy subjects, three different classifiers were compared: K-nearest neighbors (K-NN), ensemble AdaBoost classifier, and support vector machines (SVM). For predicting PD based on kinematic and pressure features of handwriting, the best performing model was SVM with classification accuracy of Pacc=81.3% (sensitivity Psen=87.4% and specificity of Pspe=80.9%). When evaluated separately, pressure features proved to be relevant for PD diagnosis, yielding Pacc=82.5% compared to Pacc=75.4% using kinematic features. Experimental results showed that an analysis of kinematic and pressure features during handwriting can help assess subtle characteristics of handwriting and discriminate between PD patients and healthy controls. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of forward (ear-canal) and reverse (round-window) sound stimulation of the cochlea.

PubMed

Stieger, Christof; Rosowski, John J; Nakajima, Hideko Heidi

2013-07-01

The cochlea is normally driven with "forward" stimulation, in which sound is introduced to the ear canal. Alternatively, the cochlea can be stimulated at the round window (RW) using an actuator. During RW "reverse" stimulation, the acoustic flow starting at the RW does not necessarily take the same path as during forward stimulation. To understand the differences between forward and reverse stimulation, we measured ear-canal pressure, stapes velocity, RW velocity, and intracochlear pressures in scala vestibuli (SV) and scala tympani (ST) of fresh human temporal bones. During forward stimulation, the cochlear drive (differential pressure across the partition) results from the large difference in magnitude between the pressures of SV and ST, which occurs due to the high compliance of the RW. During reverse stimulation, the relatively high impedance of the middle ear causes the pressures of SV and ST to have similar magnitudes, and the differential pressure results primarily from the difference in phase of the pressures. Furthermore, the sound path differs between forward and reverse stimulation, such that motion through a third window is more significant during reverse stimulation. Additionally, we determined that although stapes velocity is a good estimate of cochlear drive during forward stimulation, it is not a good measure during reverse stimulation. This article is part of a special issue entitled "MEMRO 2012". Copyright © 2012 Elsevier B.V. All rights reserved.

Differential contributions of theobromine and caffeine on mood, psychomotor performance and blood pressure.

PubMed

Mitchell, E S; Slettenaar, M; vd Meer, N; Transler, C; Jans, L; Quadt, F; Berry, M

2011-10-24

The combination of theobromine and caffeine, methylxanthines found in chocolate, has previously been shown to improve mood and cognition. However, it is unknown whether these molecules act synergistically. This study tested the hypothesis that a combination of caffeine and theobromine has synergistic effects on cognition, mood and blood pressure in 24 healthy female subjects. The effects of theobromine (700 mg), caffeine (120 mg) or the combination of both, or placebo were tested on mood (the Bond-Lader visual analog scale), psychomotor performance (the Digit Symbol Substitution Test (DSST)) and blood pressure before and at 1, 2 and 3 h after administration. Theobromine alone decreased self-reported calmness 3h after ingestion and lowered blood pressure relative to placebo 1 h after ingestion. Caffeine increased self-reported alertness 1, 2 and 3h after ingestion and contentedness 1 and 2 h after ingestion, and increased blood pressure relative to placebo (at 1 h). The combination of caffeine+theobromine had similar effects as caffeine alone on mood, but with no effect on blood pressure. There was no treatment effect on DSST performance. Together these results suggest that theobromine and caffeine could have differential effects on mood and blood pressure. It was tentatively concluded that caffeine may have more CNS-mediated effects on alertness, while theobromine may be acting primarily via peripheral physiological changes. Copyright © 2011 Elsevier Inc. All rights reserved.

Gene selection with multiple ordering criteria.

PubMed

Chen, James J; Tsai, Chen-An; Tzeng, Shengli; Chen, Chun-Houh

2007-03-05

A microarray study may select different differentially expressed gene sets because of different selection criteria. For example, the fold-change and p-value are two commonly known criteria to select differentially expressed genes under two experimental conditions. These two selection criteria often result in incompatible selected gene sets. Also, in a two-factor, say, treatment by time experiment, the investigator may be interested in one gene list that responds to both treatment and time effects. We propose three layer ranking algorithms, point-admissible, line-admissible (convex), and Pareto, to provide a preference gene list from multiple gene lists generated by different ranking criteria. Using the public colon data as an example, the layer ranking algorithms are applied to the three univariate ranking criteria, fold-change, p-value, and frequency of selections by the SVM-RFE classifier. A simulation experiment shows that for experiments with small or moderate sample sizes (less than 20 per group) and detecting a 4-fold change or less, the two-dimensional (p-value and fold-change) convex layer ranking selects differentially expressed genes with generally lower FDR and higher power than the standard p-value ranking. Three applications are presented. The first application illustrates a use of the layer rankings to potentially improve predictive accuracy. The second application illustrates an application to a two-factor experiment involving two dose levels and two time points. The layer rankings are applied to selecting differentially expressed genes relating to the dose and time effects. In the third application, the layer rankings are applied to a benchmark data set consisting of three dilution concentrations to provide a ranking system from a long list of differentially expressed genes generated from the three dilution concentrations. The layer ranking algorithms are useful to help investigators in selecting the most promising genes from multiple gene lists generated by different filter, normalization, or analysis methods for various objectives.

High Pressure Strength Study on NaCl

NASA Astrophysics Data System (ADS)

Mi, Z.; Shieh, S. R.; High Pressure Mineral Physics Group

2010-12-01

Yield strength is regarded as one important property related to rheological characteristics of minerals in the Earth’s interior. The strength study of NaCl, a popular pressure medium in static high pressure experiments, has been carried out under non-hydrostatic conditions in a diamond anvil cell up to 43 GPa at room temperature using radial energy dispersive X-ray diffraction technique. Phase transformation from B1 (rock salt structure) to B2 (CsCl structure) starts at 29.4 GPa, and is complete at 32.1 GPa. Bulk modulus obtained by third order Birch-Manurgham equation of state is 25.5 GPa with pressure derivative 4.6 for B1 phase, and 30.78 GPa with pressure derivative 4.32 GPa for B2 phase, which are in a good agreement with previous studies. The differential stress of NaCl B1 phase shows very gentle increase with pressure, which indicates that NaCl is a very good pressure-transmitting medium at pressure below 30 GPa. However, the differential stress increases more abruptly for B2 phase and this may imply that NaCl can no longer be regarded as a “soft” pressure medium at very high pressures. For B1 phase, (111) is the strongest plane and (200) is the weakest plane, while (200) becomes the strongest plane in B2 phase. Pure NaCl is weaker than mixture MgO and NaCl, which indicates that soft material become stronger when mixed with hard material. The yield strength of B2 obtained through energy dispersive X-ray diffraction technique increase linearly, while the value derived by pressure gradient method shows jagged trend.

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.

The association of feeding behaviour with the resistance and tolerance to parasites in recently diverged sticklebacks.

PubMed

Anaya-Rojas, Jaime M; Brunner, Franziska S; Sommer, Nina; Seehausen, Ole; Eizaguirre, Christophe; Matthews, Blake

2016-11-01

Divergent natural selection regimes can contribute to adaptive population divergence, but can be sensitive to human-mediated environmental change. Nutrient loading of aquatic ecosystems, for example, might modify selection pressures by altering the abundance and distribution of resources and the prevalence and infectivity of parasites. Here, we used a mesocosm experiment to test for interactive effects of nutrient loading and parasitism on host condition and feeding ecology. Specifically, we investigated whether the common fish parasite Gyrodactylus sp. differentially affected recently diverged lake and stream ecotypes of three-spined stickleback (Gasterosteus aculeatus). We found that the stream ecotype had a higher resistance to Gyrodactylus sp. infections than the lake ecotype, and that both ecotypes experienced a cost of parasitism, indicated by negative relationships between parasite load and both stomach fullness and body condition. Overall, our results suggest that in the early stages of adaptive population divergence of hosts, parasites can affect host resistance, body condition and diet. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

High-temperature measurements of methane and acetylene using quantum cascade laser absorption near 8 μm

NASA Astrophysics Data System (ADS)

Sajid, M. B.; Javed, T.; Farooq, A.

2015-04-01

The mid-infrared wavelength region near 8 μm contains absorption bands of several molecules such as water vapor, hydrogen peroxide, nitrous oxide, methane and acetylene. A new laser absorption sensor based on the ν4 band of methane and the ν4+ν5 band of acetylene is reported for interference-free, time-resolved measurements under combustion-relevant conditions. A detailed line-selection procedure was used to identify optimum transitions. Methane and acetylene were measured at the line centers of Q12 (1303.5 cm-1) and P23 (1275.5 cm-1) transitions, respectively. High-temperature absorption cross sections of methane and acetylene were measured at peaks (on-line) and valleys (off-line) of the selected absorption transitions. The differential absorption strategy was employed to eliminate interference absorption from large hydrocarbons. Experiments were performed behind reflected shock waves over a temperature range of 1200-2200 K, between pressures of 1-4 atm. The diagnostics were then applied to measure the respective species time-history profiles during the shock-heated pyrolysis of n-pentane.

Molecular evolution of pentatricopeptide repeat genes reveals truncation in species lacking an editing target and structural domains under distinct selective pressures.

PubMed

Hayes, Michael L; Giang, Karolyn; Mulligan, R Michael

2012-05-14

Pentatricopeptide repeat (PPR) proteins are required for numerous RNA processing events in plant organelles including C-to-U editing, splicing, stabilization, and cleavage. Fifteen PPR proteins are known to be required for RNA editing at 21 sites in Arabidopsis chloroplasts, and belong to the PLS class of PPR proteins. In this study, we investigate the co-evolution of four PPR genes (CRR4, CRR21, CLB19, and OTP82) and their six editing targets in Brassicaceae species. PPR genes are composed of approximately 10 to 20 tandem repeats and each repeat has two α-helical regions, helix A and helix B, that are separated by short coil regions. Each repeat and structural feature was examined to determine the selective pressures on these regions. All of the PPR genes examined are under strong negative selection. Multiple independent losses of editing site targets are observed for both CRR21 and OTP82. In several species lacking the known editing target for CRR21, PPR genes are truncated near the 17th PPR repeat. The coding sequences of the truncated CRR21 genes are maintained under strong negative selection; however, the 3' UTR sequences beyond the truncation site have substantially diverged. Phylogenetic analyses of four PPR genes show that sequences corresponding to helix A are high compared to helix B sequences. Differential evolutionary selection of helix A versus helix B is observed in both plant and mammalian PPR genes. PPR genes and their cognate editing sites are mutually constrained in evolution. Editing sites are frequently lost by replacement of an edited C with a genomic T. After the loss of an editing site, the PPR genes are observed with three outcomes: first, few changes are detected in some cases; second, the PPR gene is present as a pseudogene; and third, the PPR gene is present but truncated in the C-terminal region. The retention of truncated forms of CRR21 that are maintained under strong negative selection even in the absence of an editing site target suggests that unrecognized function(s) might exist for this PPR protein. PPR gene sequences that encode helix A are under strong selection, and could be involved in RNA substrate recognition.

Solar Radiation-Associated Adaptive SNP Genetic Differentiation in Wild Emmer Wheat, Triticum dicoccoides.

PubMed

Ren, Jing; Chen, Liang; Jin, Xiaoli; Zhang, Miaomiao; You, Frank M; Wang, Jirui; Frenkel, Vladimir; Yin, Xuegui; Nevo, Eviatar; Sun, Dongfa; Luo, Ming-Cheng; Peng, Junhua

2017-01-01

Whole-genome scans with large number of genetic markers provide the opportunity to investigate local adaptation in natural populations and identify candidate genes under positive selection. In the present study, adaptation genetic differentiation associated with solar radiation was investigated using 695 polymorphic SNP markers in wild emmer wheat originated in a micro-site at Yehudiyya, Israel. The test involved two solar radiation niches: (1) sun, in-between trees; and (2) shade, under tree canopy, separated apart by a distance of 2-4 m. Analysis of molecular variance showed a small (0.53%) but significant portion of overall variation between the sun and shade micro-niches, indicating a non-ignorable genetic differentiation between sun and shade habitats. Fifty SNP markers showed a medium (0.05 ≤ F ST ≤ 0.15) or high genetic differentiation ( F ST > 0.15). A total of 21 outlier loci under positive selection were identified by using four different F ST -outlier testing algorithms. The markers and genome locations under positive selection are consistent with the known patterns of selection. These results suggested that genetic differentiation between sun and shade habitats is substantial, radiation-associated, and therefore ecologically determined. Hence, the results of this study reflected effects of natural selection through solar radiation on EST-related SNP genetic diversity, resulting presumably in different adaptive complexes at a micro-scale divergence. The present work highlights the evolutionary theory and application significance of solar radiation-driven natural selection in wheat improvement.

Economic method for measuring ultra-low flow rates of fluids

NASA Technical Reports Server (NTRS)

Bogdanovic, J. A.; Keller, W. F.

1970-01-01

Capillary tube flowmeter measures ultra-low flows of very corrosive fluids /such as chlorine trifluoride and liquid fluorine/ and other liquids with reasonable accuracy. Flowmeter utilizes differential pressure transducer and operates on the principle that for laminar flow in the tube, pressure drop is proportional to flow rate.

The role of sexual and natural selection in shaping patterns of sexual dichromatism in the largest family of songbirds (Aves: Thraupidae).

PubMed

Shultz, Allison J; Burns, Kevin J

2017-04-01

Males and females can be under different evolutionary pressures if sexual and natural selection is differentially operating in each sex. As a result, many species have evolved sexual dichromatism, or differences in coloration between sexes. Although sexual dichromatism is often used as an index of the magnitude of sexual selection, sexual dichromatism is a composite trait. Here, we examine the evolution of sexual dichromatism in one of the largest and most ecologically diverse families of birds, the tanagers, using the avian visual perspective and a species-level phylogeny. Our results demonstrate that the evolutionary decreases of sexual dichromatism are more often associated with larger and more frequent changes in male plumage coloration, and evolutionary increases are not more often associated with larger changes in either sex. Furthermore, we show that the crown and ventral plumage regions are correlated with sexual dichromatism in males, and that only male plumage complexity is positively correlated with sexual dichromatism. Finally, we demonstrate that light environment is important in shaping both plumage brilliance and complexity. By conducting a multilevel analysis of plumage evolution in males and females, we show that sexual dichromatism evolves via a mosaic of sexual and natural selection in both sexes. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Genetic diversity of rice tungro spherical virus in tungro-endemic provinces of the Philippines and Indonesia.

PubMed

Azzam, O; Yambao, M L; Muhsin, M; McNally, K L; Umadhay, K M

2000-01-01

The two adjacent genes of coat protein 1 and 2 of rice tungro spherical virus (RTSV) were amplified from total RNA extracts of serologically indistinguishable field isolates from the Philippines and Indonesia, using reverse transcriptase polymerase chain reaction (RT-PCR). Digestion with HindIII and BstYI restriction endonucleases differentiated the amplified DNA products into eight distinct coat protein genotypes. These genotypes were then used as indicators of virus diversity in the field. Inter- and intra-site diversities were determined over three cropping seasons. At each of the sites surveyed, one or two main genotypes prevailed together with other related minor or mixed genotypes that did not replace the main genotype over the sampling time. The cluster of genotypes found at the Philippines sites was significantly different from the one at the Indonesia sites, suggesting geographic isolation for virus populations. Phylogenetic studies based on the nucleotide sequences of 38 selected isolates confirm the spatial distribution of RTSV virus populations but show that gene flow may occur between populations. Under the present conditions, rice varieties do not seem to exert selective pressure on the virus populations. Based on the selective constraints in the coat protein amino acid sequences and the virus genetic composition per site, a negative selection model followed by random-sampling events due to vector transmissions is proposed to explain the inter-site diversity observed.

Variable oxygen/nitrogen enriched intake air system for internal combustion engine applications

DOEpatents

Poola, Ramesh B.; Sekar, Ramanujam R.; Cole, Roger L.

1997-01-01

An air supply control system for selectively supplying ambient air, oxygen enriched air and nitrogen enriched air to an intake of an internal combustion engine includes an air mixing chamber that is in fluid communication with the air intake. At least a portion of the ambient air flowing to the mixing chamber is selectively diverted through a secondary path that includes a selectively permeable air separating membrane device due a differential pressure established across the air separating membrane. The permeable membrane device separates a portion of the nitrogen in the ambient air so that oxygen enriched air (permeate) and nitrogen enriched air (retentate) are produced. The oxygen enriched air and the nitrogen enriched air can be selectively supplied to the mixing chamber or expelled to atmosphere. Alternatively, a portion of the nitrogen enriched air can be supplied through another control valve to a monatomic-nitrogen plasma generator device so that atomic nitrogen produced from the nitrogen enriched air can be then injected into the exhaust of the engine. The oxygen enriched air or the nitrogen enriched air becomes mixed with the ambient air in the mixing chamber and then the mixed air is supplied to the intake of the engine. As a result, the air being supplied to the intake of the engine can be regulated with respect to the concentration of oxygen and/or nitrogen.

Elastin Is Differentially Regulated by Pressure Therapy in a Porcine Model of Hypertrophic Scar.

PubMed

Carney, Bonnie C; Liu, Zekun; Alkhalil, Abdulnaser; Travis, Taryn E; Ramella-Roman, Jessica; Moffatt, Lauren T; Shupp, Jeffrey W

Beneficial effects of pressure therapy for hypertrophic scars have been reported, but the mechanisms of action are not fully understood. This study evaluated elastin and its contribution to scar pliability. The relationship between changes in Vancouver Scar Scale (VSS) scores of pressure-treated scars and differential regulation of elastin was assessed. Hypertrophic scars were created and assessed weekly using VSS and biopsy procurement. Pressure treatment began on day 70 postinjury. Treated scars were compared with untreated shams. Treatment lasted 2 weeks, through day 84, and scars were assessed weekly through day 126. Transcript and protein levels of elastin were quantified. Pressure treatment resulted in lower VSS scores compared with sham-treated scars. Pliability (VSSP) was a key contributor to this difference. At day 70 pretreatment, VSSP = 2. Without treatment, sham-treated scars became less pliable, while pressure-treated scars became more pliable. The percentage of elastin in scars at day 70 was higher than in uninjured skin. Following treatment, the percentage of elastin increased and continued to increase through day 126. Untreated sham scars did not show a similar increase. Quantification of Verhoeff-Van Gieson staining corroborated the findings and immunofluorescence revealed the alignment of elastin fibers. Pressure treatment results in increased protein level expression of elastin compared with sham-untreated scars. These findings further characterize the extracellular matrix's response to the application of pressure as a scar treatment, which will contribute to the refinement of rehabilitation practices and ultimately improvements in functional and psychosocial outcomes for patients.

Evolutionary ecology of resprouting and seeding in fire-prone ecosystems

USGS Publications Warehouse

Pausas, Juli G.; Keeley, Jon E.

2014-01-01

There are two broad mechanisms by which plant populations persist under recurrent disturbances: resprouting from surviving tissues, and seedling recruitment. Species can have one of these mechanisms or both. However, a coherent framework explaining the differential evolutionary pressures driving these regeneration mechanisms is lacking. We propose a bottom-up approach in addressing this question that considers the relative survivorship of adults and juveniles in an evolutionary context, based on two assumptions. First, resprouting and seeding can be interpreted by analogy with annual versus perennial life histories; that is, if we consider disturbance cycles to be analogous to annual cycles, then resprouting species are analogous to the perennial life history with iteroparous reproduction, and obligate seeding species that survive disturbances solely through seed banks are analogous to the annual life history with semelparous reproduction. Secondly, changes in the selective regimes differentially modify the survival rates of adults and juveniles and thus the relative costs and benefits of resprouting versus seeding. Our approach provides a framework for understanding temporal and spatial variation in resprouting and seeding under crown-fire regimes. It accounts for patterns of coexistence and environmental changes that contribute to the evolution of seeding from resprouting ancestors.