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Sample records for high reproductive rates

  1. Decreased reproductive rates in sheep fed a high selenium diet

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High Se-containing forages grow on seleniferous soils in many parts of the United States and throughout the world. Selenium is an essential trace element that is required for many physiological processes but can also be either acutely or chronically toxic to livestock. Anecdotal reports of decrease...

  2. High rates of pregnancy loss by subordinates leads to high reproductive skew in wild golden lion tamarins (Leontopithecus rosalia)

    PubMed Central

    Henry, MaLinda D.; Hankerson, Sarah J.; Siani, Jennifer M.; French, Jeffrey A.; Dietz, James M.

    2013-01-01

    Across taxa, cooperative breeding has been associated with high reproductive skew. Cooperatively breeding golden lion tamarins (Leontopithecus rosalia) were long thought to have a monogynous mating system in which reproduction was limited to a single dominant female. Subordinates with few reproductive opportunities delayed dispersal and remained in the natal group to provide alloparental care to siblings, thus allowing dominant reproductive females to meet the energetic needs associated with high rates of reproduction and successful infant rearing. The goal of this study was to re-assess monogyny in wild golden lion tamarin groups based upon pregnancy diagnoses that used non-invasive enzyme immunoassay for progesterone and cortisol, combined with weekly data on individual weight gain, bi-annual physical examinations noting pregnancy and lactation status and daily behavioral observations. We established quantitative and qualitative criteria to detect and determine the timing of pregnancies that did not result in the birth of infants. Pregnancy polygyny occurred in 83% of golden lion tamarin groups studied. The loss of 64% of subordinate pregnancies compared to only 15% by dominant females limited reproductive success mainly to dominant females, thus maintaining high reproductive skew in female golden lion tamarins. Pregnancy loss by subordinate adults did not appear to result from dominant interference in subordinate hormonal mechanisms, but more likely resulted from subordinate abandonment of newborn infants to mitigate dominant aggression. PMID:23454002

  3. A highly infective plant-associated bacterium influences reproductive rates in pea aphids

    PubMed Central

    Hendry, Tory A.; Clark, Kelley J.; Baltrus, David A.

    2016-01-01

    Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction. PMID:26998321

  4. A highly infective plant-associated bacterium influences reproductive rates in pea aphids.

    PubMed

    Hendry, Tory A; Clark, Kelley J; Baltrus, David A

    2016-02-01

    Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction. PMID:26998321

  5. Reproductive performance of high growth rate gilts inseminated at an early age.

    PubMed

    Kummer, Rafael; Bernardi, Mari Lourdes; Wentz, Ivo; Bortolozzo, Fernando Pandolfo

    2006-11-01

    The aim of this work was to determine if gilts, which have a high growth rate (GR) could be mated earlier without reducing the reproductive performance or increasing the culling rate up to the third parity. Gilts of Camborough 22 (C22, n=568) breeding were mated and allocated into three groups according to weight and age on the insemination day. G1 (n=164)-gilts with a GR>or=700 g/d and inseminated at <210 d. G2 (n=165)-gilts with a GR>or=700 g/d and inseminated at >or=210 d. G3 (n=239)-gilts with a GR<700 g/d and inseminated at >or=210 d. All females were fed ad libitum from 150 d on and were inseminated at their second estrus or later. The minimum weight at mating was 127 kg. Three parities were studied, with farrowing rate, litter size and culling rate being compared. At the first parity, G2 gilts produced, on average, one more piglet than the other groups (P<0.05). However, when analyzing three parities, there were no differences in total born (11.6 x 12.3 x 11.7), farrowing rate (87.1% x 88.7% x 89.8%) and culling rate (30.2% x 25.3% x 28.2%) among G1-G3 groups, respectively (P>0.05). In conclusion, gilts, which had a minimum weight of 127 kg can be inseminated at their second or greater estrus, between 185 and <210 d of age, without impairing their productive performance over three parities. PMID:16431043

  6. Effects of high selenium forages on reproduction in sheep

    Technology Transfer Automated Retrieval System (TEKTRAN)

    High Se-containing forages grow on seleniferous soils in many parts of world and can cause acute or chronic selenosis in livestock. Anecdotal reports of decreased reproductive rates in livestock grazing seleniferous forages have been reported and it has been speculated that reproductive failure is o...

  7. Transmission rate and reproductive number of the H5N1 highly pathogenic avian influenza virus during the December 2005-July 2008 epidemic in Nigeria.

    PubMed

    Bett, B; Henning, J; Abdu, P; Okike, I; Poole, J; Young, J; Randolph, T F; Perry, B D

    2014-02-01

    We quantified the between-village transmission rate, β (the rate of transmission of H5N1 HPAI virus per effective contact), and the reproductive number, Re (the average number of outbreaks caused by one infectious village during its entire infectious period), of H5N1 highly pathogenic avian influenza (HPAI) virus in Nigeria using outbreak data collected between December 2005 and July 2008. We classified the outbreaks into two phases to assess the effectiveness of the control measures implemented. Phase 1 (December 2005-October 2006) represents the period when the Federal Government of Nigeria managed the HPAI surveillance and response measures, while Phase 2 (November 2006-July 2008) represents the time during which the Nigeria Avian Influenza Control and Human Pandemic Preparedness project (NAICP), funded by a World Bank credit of US$ 50 million, had taken over the management of most of the interventions. We used a total of 204 outbreaks from 176 villages that occurred in 78 local government areas of 25 states. The compartmental susceptible-infectious model was used as the analytical tool. Means and 95% percentile confidence intervals were obtained using bootstrapping techniques. The overall mean β (assuming a duration of infectiousness, T, of 12 days) was 0.07/day (95% percentile confidence interval: 0.06-0.09). The first and second phases of the epidemic had comparable β estimates of 0.06/day (0.04-0.09) and 0.08/day (0.06-0.10), respectively. The Re of the virus associated with these β and T estimates was 0.9 (0.7-1.1); the first and second phases of the epidemic had Re of 0.84 (0.5-1.2) and 0.9 (0.6-1.2), respectively. We conclude that the intervention measures implemented in the second phase of the epidemic had comparable effects to those implemented during the first phase and that the Re of the epidemic was low, indicating that the Nigeria H5N1 HPAI epidemic was unstable. PMID:22925404

  8. Reproductive Rates in Australian Rodents Are Related to Phylogeny

    PubMed Central

    Geffen, Eli; Rowe, Kevin C.; Yom-Tov, Yoram

    2011-01-01

    Background The native rodents of Australia are commonly divided into two groups based on the time of their colonization of the Sahulian continent, which encompasses Australia, New Guinea, and the adjacent islands. The first group, the “old endemics,” is a diverse assemblage of 34 genera that are descended from a single colonization of the continent during the Pliocene. A second group, the “new endemics,” is composed of several native Rattus species that are descended from a single colonization during the Pleistocene. Finally, a third group is composed of three non-native species of Rattus and Mus introduced into Australia by humans over the last 200 years. Previous studies have claimed that the three groups differ in their reproductive rates and that this variation in rates is associated with the unique environmental conditions across Australia. We examined these hypotheses using phylogenetically controlled methods. Methodology and Results We examined the relationship between the reproductive rates of the Australian rodents and the environmental variations across the continent, as well as the epoch of their colonization of the continent. Our results revealed no significant correlation with environmental variables but a significant association between colonization age and all the reproductive parameters examined. Discussion Based on a larger phylogeny of the subfamily Murinae, we showed that significant differences in reproductive rates among colonization groups are shared with their closest relatives outside Sahul. Therefore, the lower reproductive rates in the old endemics are more likely to be the result of phylogenetic history and conservation of traits than an adaptation to the Australian environment. In the new endemics, we found a trend of increasing reproductive rates with diversification. We suggest that the differences in reproductive rates of the old endemic rodents and the native Rattus represent alternative adaptive strategies that have allowed

  9. Reproductive rate, not dominance status, affects fecal glucocorticoid levels in breeding female meerkats.

    PubMed

    Barrette, Marie-France; Monfort, Steven L; Festa-Bianchet, Marco; Clutton-Brock, Tim H; Russell, Andrew F

    2012-04-01

    Glucocorticoid hormones (GCs) have been studied intensively to understand the associations between physiological stress and reproductive skew in animal societies. However, we have little appreciation of the range of either natural levels within and among individuals, or the associations among dominance status, reproductive rate and GCs levels during breeding. To address these shortcomings, we examined variation in fecal glucocorticoid metabolites (fGC) during breeding periods in free-ranging female meerkats (Suricata suricatta) over 11 years. The vast majority of variation in fGC levels was found within breeding events by the same female (~87%), with the remaining variation arising among breeding events and among females. Concentrations of fGC generally tripled as pregnancy progressed. However, females with a high reproductive rate, defined as those conceiving within a month following parturition (mean = 9 days postpartum), showed significant reductions in fGC in the final 2 weeks before parturition. Despite these reductions, females with a high reproductive rate had higher fGC levels at conception of the following litter than those breeding at a low rate. After controlling for the higher reproductive rate of dominants, we found no association between levels of fGC and either age or dominance status. Our results suggest that one should be cautious about interpreting associations between dominance status, reproductive skew and GCs levels, without knowledge of the natural variation in GCs levels within and among females. PMID:22210199

  10. High-resolution color photographic reproductions

    NASA Astrophysics Data System (ADS)

    McCann, John J.

    1997-04-01

    This paper will describe a fine-art reproduction process that: captures painting information with high-resolution color photographs; scans the information into a 300 megabyte digital file; performs a 3D color calibration in a dedicated hardware color-transform circuit; makes a master positive color transparency and makes a reproduction on polaroid color print film. The master transparency can be used to expose a large number of images. This combines the efficiency of instant photography with the color fidelity of digital color transforms.

  11. High Rate Digital Demodulator ASIC

    NASA Technical Reports Server (NTRS)

    Ghuman, Parminder; Sheikh, Salman; Koubek, Steve; Hoy, Scott; Gray, Andrew

    1998-01-01

    The architecture of High Rate (600 Mega-bits per second) Digital Demodulator (HRDD) ASIC capable of demodulating BPSK and QPSK modulated data is presented in this paper. The advantages of all-digital processing include increased flexibility and reliability with reduced reproduction costs. Conventional serial digital processing would require high processing rates necessitating a hardware implementation in other than CMOS technology such as Gallium Arsenide (GaAs) which has high cost and power requirements. It is more desirable to use CMOS technology with its lower power requirements and higher gate density. However, digital demodulation of high data rates in CMOS requires parallel algorithms to process the sampled data at a rate lower than the data rate. The parallel processing algorithms described here were developed jointly by NASA's Goddard Space Flight Center (GSFC) and the Jet Propulsion Laboratory (JPL). The resulting all-digital receiver has the capability to demodulate BPSK, QPSK, OQPSK, and DQPSK at data rates in excess of 300 Mega-bits per second (Mbps) per channel. This paper will provide an overview of the parallel architecture and features of the HRDR ASIC. In addition, this paper will provide an over-view of the implementation of the hardware architectures used to create flexibility over conventional high rate analog or hybrid receivers. This flexibility includes a wide range of data rates, modulation schemes, and operating environments. In conclusion it will be shown how this high rate digital demodulator can be used with an off-the-shelf A/D and a flexible analog front end, both of which are numerically computer controlled, to produce a very flexible, low cost high rate digital receiver.

  12. Exploring individual quality: Basal metabolic rate and reproductive performance in storm-petrels

    USGS Publications Warehouse

    Blackmer, A.L.; Mauck, R.A.; Ackerman, J.T.; Huntington, C.E.; Nevitt, G.A.; Williams, J.B.

    2005-01-01

    Despite evidence that some individuals achieve both superior reproductive performance and high survivorship, the factors underlying variation in individual quality are not well understood. The compensation and increased-intake hypotheses predict that basal metabolic rate (BMR) influences reproductive performance; if so, variation in BMR may be related to differences in individual quality. We evaluated whether BMR measured during the incubation period provides a proximate explanation for variation in individual quality by measuring the BMRs and reproductive performance of Leach's storm-petrels (Oceanodroma leucorhoa) breeding on Kent Island, New Brunswick, Canada, during 2000 and 2001. We statistically controlled for internal (body mass, breeding age, sex) and external (year, date, time of day) effects on BMR. We found that males with relatively low BMRs hatched their eggs earlier in the season and that their chicks' wing growth rates were faster compared to males with relatively high BMRs. Conversely, BMR was not related to egg volume, hatching date, or chick growth rate for females or to lifetime (???23 years) hatching success for either sex. Thus, for males but not for females, our results support the compensation hypothesis. This hypothesis predicts that animals with low BMRs will achieve better reproductive performance than animals with high BMRs because they have lower self-maintenance costs and therefore can apportion more energy to reproduction. These results provide evidence that intraspecific variation in reproductive performance is related to BMR and suggest that BMR may influence individual quality in males. ?? The Author 2005. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved.

  13. Variability in temporary emigration rates of individually marked female Weddell seals prior to first reproduction.

    PubMed

    Stauffer, Glenn E; Rotella, Jay J; Garrott, Robert A

    2013-05-01

    In many species, temporary emigration (TE) is a phenomenon, often indicative of life-history characteristics such as dormancy, skipped reproduction, or partial migration, whereby certain individuals in a population are temporarily unobservable at a particular site. TE may be a flexible condition-dependent strategy that allows individuals to mitigate effects of adverse conditions. Consequently, TE rates ought to be highly variable, but sources of variations are poorly understood for most species. We used data from known-aged female Weddell seals (Leptonychotes weddellii) tagged in Erebus Bay, Antarctica, to investigate sources of variation in TE rates prior to reproduction and to evaluate possible implications for age-specific probability of first reproduction. TE rates were near 1 the year after birth, decreased to an average of 0.15 (SE = 0.01) by age 8, and were similar thereafter. TE rates varied substantially from year-to-year and were lower for seals that attended reproductive colonies the previous year than for seals that did not attend (e.g., ψ(i,age 8)(UU) - ψ(i, age 8)(PU) = 0.22). Recruitment rates were marginally greater for seals that did attend than for seals that did not attend colonies the previous year. For Weddell seals specifically, our results suggest that (1) motivation to attend colonies varied temporally, (2) as seals grew older they had increased motivation to attend even before reproductive maturity, and (3) seals appear to follow various attendance strategies. More broadly, our results support the idea of TE as a variable, condition-dependent strategy, and highlight the utility of TE models for providing population and life-history insights for diverse taxa. PMID:23053233

  14. Individual variation in reproductive costs of reproduction: high-quality females always do better.

    PubMed

    Hamel, Sandra; Côté, Steeve D; Gaillard, Jean-Michel; Festa-Bianchet, Marco

    2009-01-01

    1. Although life-history theory predicts substantial costs of reproduction, individuals often show positive correlations among life-history traits, rather than trade-offs. The apparent absence of reproductive costs may result from heterogeneity in individual quality. 2. Using detailed longitudinal data from three contrasted ungulate populations (mountain goats, Oreamnos americanus; bighorn sheep, Ovis canadensis; and roe deer, Capreolus capreolus), we assessed how individual quality affects the probability of detecting a cost of current reproduction on future reproduction for females. We used a composite measure of individual quality based on variations in longevity (all species), success in the last breeding opportunity before death (goats and sheep), adult mass (all species), and social rank (goats only). 3. In all species, high-quality females consistently had a higher probability of reproduction, irrespective of previous reproductive status. In mountain goats, we detected a cost of reproduction only after accounting for differences in individual quality. Only low-quality female goats were less likely to reproduce following years of breeding than of nonbreeding. Offspring survival was lower in bighorn ewes following years of successful breeding than after years when no lamb was produced, but only for low-quality females, suggesting that a cost of reproduction only occurred for low-quality females. 4. Because costs of reproduction differ among females, studies of life-history evolution must account for heterogeneity in individual quality. PMID:18700872

  15. Genotypic variation in host response to infection affects parasite reproductive rate.

    PubMed

    Tavalire, Hannah F; Blouin, Michael S; Steinauer, Michelle L

    2016-02-01

    Parasite fitness is largely influenced by a variation in host response due to the host's genetic background. Here we investigated the impact of host genotype on pathogen success in the snail vector of its castrating parasite, Schistosoma mansoni. We infected five inbred lines of Biomphalaria glabrata with two infection doses and followed their growth, reproductive output and parasite production throughout the course of infection. There was no difference in resistance to infection among inbred lines, but lines varied in their responses to infection and the numbers of parasites produced. Snails did not compensate for castration by increasing their fecundity during the early phase of infection (fecundity compensation). However, some lines were able to delay parasite shedding for up to 30 weeks, thus prolonging reproduction before the onset of castration. Here we propose this strategy as a novel defense against castrating pathogens in snails. Gigantism, a predicted outcome of castration due to energy reallocation, occurred early in infection (<15 weeks) and was not universal among the snail lines. Lines that did not show gigantism were also characterised by a high parasite production rate and low survivorship, perhaps indicating energy reallocation into parasite production and costly immune defense. We observed no differences in total parasite production among lines throughout the entire course of infection, although lines differed in their parasite reproductive rate. The average rate of parasite production varied among lines from 1300 to 2450 cercariae within a single 2h shedding period, resulting in a total production of 6981-29,509 cercariae over the lifetime of a single snail. Regardless of genetic background, snail size was a strong predictor of parasite reproduction: each millimetre increase in snail size at the time of the first shed resulted in up to 3500 more cercariae over the lifetime of the snail. The results of this study provide a detailed picture of

  16. The high cost of reproduction in sea otters necessitates unique physiological adaptations.

    PubMed

    Thometz, Nicole M; Kendall, Traci L; Richter, Beau P; Williams, Terrie M

    2016-08-01

    Superimposed on inherently high basal metabolic demands, the additional energetic requirements of reproduction can push female sea otters beyond physiological limits. Indeed, the resulting energy imbalance contributes to disproportionately high rates of mortality at the end of lactation in this species. To examine and quantify metabolic changes associated with reproduction, we measured the resting metabolic rate (RMR) of a female sea otter across gestation, lactation and non-reproductive periods. Concurrently, measurements were made on a non-breeding control female. Our results suggest that RMR declines during gestation. Conversely, RMR increases during lactation, reaches a peak at 3-4 months postpartum, and remains elevated until weaning. Combining these direct measurements with published data, we found the cost of pup rearing to be significantly higher than previously estimated. High baseline energy demands and limited energy reserves, combined with significant lactation and pup rearing costs, appear to necessitate metabolic and thermal lability during key reproductive stages. PMID:27489214

  17. Macroevolutionary speciation rates are decoupled from the evolution of intrinsic reproductive isolation in Drosophila and birds.

    PubMed

    Rabosky, Daniel L; Matute, Daniel R

    2013-09-17

    The rate at which speciation occurs varies greatly among different kinds of organisms and is frequently assumed to result from species- or clade-specific factors that influence the rate at which populations acquire reproductive isolation. This premise leads to a fundamental prediction that has never been tested: Organisms that quickly evolve prezygotic or postzygotic reproductive isolation should have faster rates of speciation than organisms that slowly acquire reproductive isolation. We combined phylogenetic estimates of speciation rates from Drosophila and birds with a method for analyzing interspecific hybridization data to test whether the rate at which individual lineages evolve reproductive isolation predicts their macroevolutionary rate of species formation. We find that some lineages evolve reproductive isolation much more quickly than others, but this variation is decoupled from rates of speciation as measured on phylogenetic trees. For the clades examined here, reproductive isolation--especially intrinsic, postzygotic isolation--does not seem to be the rate-limiting control on macroevolutionary diversification dynamics. These results suggest that factors associated with intrinsic reproductive isolation may have less to do with the tremendous variation in species diversity across the evolutionary tree of life than is generally assumed. PMID:24003144

  18. Macroevolutionary speciation rates are decoupled from the evolution of intrinsic reproductive isolation in Drosophila and birds

    PubMed Central

    Rabosky, Daniel L.; Matute, Daniel R.

    2013-01-01

    The rate at which speciation occurs varies greatly among different kinds of organisms and is frequently assumed to result from species- or clade-specific factors that influence the rate at which populations acquire reproductive isolation. This premise leads to a fundamental prediction that has never been tested: Organisms that quickly evolve prezygotic or postzygotic reproductive isolation should have faster rates of speciation than organisms that slowly acquire reproductive isolation. We combined phylogenetic estimates of speciation rates from Drosophila and birds with a method for analyzing interspecific hybridization data to test whether the rate at which individual lineages evolve reproductive isolation predicts their macroevolutionary rate of species formation. We find that some lineages evolve reproductive isolation much more quickly than others, but this variation is decoupled from rates of speciation as measured on phylogenetic trees. For the clades examined here, reproductive isolation—especially intrinsic, postzygotic isolation—does not seem to be the rate-limiting control on macroevolutionary diversification dynamics. These results suggest that factors associated with intrinsic reproductive isolation may have less to do with the tremendous variation in species diversity across the evolutionary tree of life than is generally assumed. PMID:24003144

  19. Individual heterogeneity in reproductive rates and cost of reproduction in a long-lived vertebrate

    PubMed Central

    Chambert, Thierry; Rotella, Jay J; Higgs, Megan D; Garrott, Robert A

    2013-01-01

    Individual variation in reproductive success is a key feature of evolution, but also has important implications for predicting population responses to variable environments. Although such individual variation in reproductive outcomes has been reported in numerous studies, most analyses to date have not considered whether these realized differences were due to latent individual heterogeneity in reproduction or merely random chance causing different outcomes among like individuals. Furthermore, latent heterogeneity in fitness components might be expressed differently in contrasted environmental conditions, an issue that has only rarely been investigated. Here, we assessed (i) the potential existence of latent individual heterogeneity and (ii) the nature of its expression (fixed vs. variable) in a population of female Weddell seals (Leptonychotes weddellii), using a hierarchical modeling approach on a 30-year mark–recapture data set consisting of 954 individual encounter histories. We found strong support for the existence of latent individual heterogeneity in the population, with “robust” individuals expected to produce twice as many pups as “frail” individuals. Moreover, the expression of individual heterogeneity appeared consistent, with only mild evidence that it might be amplified when environmental conditions are severe. Finally, the explicit modeling of individual heterogeneity allowed us to detect a substantial cost of reproduction that was not evidenced when the heterogeneity was ignored. PMID:23919151

  20. Estimating Pesticide Effects on Fecundity Rates of Wild Birds Using Current Laboratory Reproduction Tests

    EPA Science Inventory

    The manuscript reviews the issues concerning the use of results on pesticide effects from laboratory avian reproduction tests for estimating potential impacts of pesticides on fecundity rates in avian population models.

  1. Low Reproductive Rate Predicts Species Sensitivity to Habitat Loss: A Meta-Analysis of Wetland Vertebrates

    PubMed Central

    Quesnelle, Pauline E.; Lindsay, Kathryn E.; Fahrig, Lenore

    2014-01-01

    We tested the hypotheses that species with greater mobility and/or higher reproductive rates are less sensitive to habitat loss than species with lower mobility and/or reproductive rates by conducting a meta-analysis of wetland vertebrate responses to wetland habitat loss. We combined data from 90 studies conducted worldwide that quantified the relationship between wetland amount in a landscape and population abundance of at least one wetland species to determine if mobility (indexed as home range size and body length) and annual reproductive rate influence species responses to wetland loss. When analyzed across all taxa, animals with higher reproductive rates were less sensitive to wetland loss. Surprisingly, we did not find an effect of mobility on response to wetland loss. Overall, wetland mammals and birds were more sensitive to wetland loss than were reptiles and amphibians. Our results suggest that dispersal between habitat patches is less important than species’ reproductive rates for population persistence in fragmented landscapes. This implies that immigration and colonization rate is most strongly related to reproduction, which determines the total number of potential colonists. PMID:24651675

  2. Growth rates, reproductive phenology, and pollination ecology of Espeletia grandiflora (Asteraceae), a giant Andean caulescent rosette.

    PubMed

    Fagua, J C; Gonzalez, V H

    2007-01-01

    From March 2001 to December 2002, we studied the reproductive phenology, pollination ecology, and growth rates of Espeletia grandiflora Humb. and Bonpl. (Asteraceae), a giant caulescent rosette from the Páramos of the Eastern Andes of Colombia. Espeletia grandiflora was found to be predominantly allogamous and strongly self-incompatible. Bumblebees (Bombus rubicundus and B. funebris) were the major pollinators of E. grandiflora, although moths, hummingbirds, flies, and beetles also visited flowers. Inflorescence development began in March and continued through August to September. Plants flowered for 30 - 96 days with a peak from the beginning of October through November. The percentage of flowering plants strongly differed among size classes and between both years. Seed dispersal occurred as early as September through May of the following year. The average absolute growth rate for juveniles and adults rate was 7.6 cm/year. Given the scarcity of floral visitors at high altitudes due to climatic conditions, we suggest that even small contributions from a wide range of pollinators might be advantageous for pollination of E. grandiflora. Long-term studies on different populations of E. grandiflora are required to determine if the high growth rates are representative, to quantify the variation in the flowering behavior within and among populations, and to establish if nocturnal pollination is a trait that is exclusive to our population of E. grandiflora. PMID:17066366

  3. Senescence rates and late adulthood reproductive success are strongly influenced by personality in a long-lived seabird

    PubMed Central

    Patrick, Samantha C.; Weimerskirch, Henri

    2015-01-01

    Studies are increasingly demonstrating that individuals differ in their rate of ageing, and this is postulated to emerge from a trade-off between current and future reproduction. Recent theory predicts a correlation between individual personality and life-history strategy, and from this comes the prediction that personality may predict the intensity of senescence. Here we show that boldness correlates with reproductive success and foraging behaviour in wandering albatrosses, with strong sex-specific differences. Shy males show a strong decline in reproductive performance with age, and bold females have lower reproductive success in later adulthood. In both sexes, bolder birds have longer foraging trips and gain more mass per trip as they get older. However, the benefit of this behaviour appears to differ between the sexes, such that it is only matched by high reproductive success in males. Together our results suggest that personality linked foraging adaptations with age are strongly sex-specific in their fitness benefits and that the impact of boldness on senescence is linked to ecological parameters. PMID:25473008

  4. Senescence rates and late adulthood reproductive success are strongly influenced by personality in a long-lived seabird.

    PubMed

    Patrick, Samantha C; Weimerskirch, Henri

    2015-01-22

    Studies are increasingly demonstrating that individuals differ in their rate of ageing, and this is postulated to emerge from a trade-off between current and future reproduction. Recent theory predicts a correlation between individual personality and life-history strategy, and from this comes the prediction that personality may predict the intensity of senescence. Here we show that boldness correlates with reproductive success and foraging behaviour in wandering albatrosses, with strong sex-specific differences. Shy males show a strong decline in reproductive performance with age, and bold females have lower reproductive success in later adulthood. In both sexes, bolder birds have longer foraging trips and gain more mass per trip as they get older. However, the benefit of this behaviour appears to differ between the sexes, such that it is only matched by high reproductive success in males. Together our results suggest that personality linked foraging adaptations with age are strongly sex-specific in their fitness benefits and that the impact of boldness on senescence is linked to ecological parameters. PMID:25473008

  5. Age at first reproduction explains rate variation in the strepsirrhine molecular clock

    PubMed Central

    Tsantes, C.; Steiper, M. E.

    2009-01-01

    Although the molecular clock hypothesis posits that the rate of molecular change is constant over time, there is evidence that rates vary among lineages. Some of the strongest evidence for variable molecular rates comes from the primates; e.g., the “hominoid slowdown.” These rate differences are hypothesized to correlate with certain species attributes, such as generation time and body size. Here, we examine rates of molecular change in the strepsirrhine suborder of primates and test whether body size or age at first reproduction (a proxy for generation time) explains patterns of rate variation better than a null model where the molecular clock is independent of these factors. To examine these models, we analyzed DNA sequences from four pairs of recently diverged strepsirrhine sister taxa to estimate molecular rates by using sign tests, likelihood ratio tests, and regression analyses. Our analysis does not support a model where body weight or age at first reproduction strongly influences rates of molecular evolution across mitochondrial and nuclear sites. Instead, our analysis supports a model where age at first reproduction influences neutral evolution in the nuclear genome. This study supports the generation time hypothesis for rate variation in the nuclear molecular clock. Molecular clock variation due to generation time may help to resolve the discordance between molecular and paleontological estimates for divergence date estimates in primate evolution. PMID:19841267

  6. Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species.

    PubMed

    Foote, Andrew D

    2008-04-23

    The strength of selection to increase the span of a life stage is dependent upon individuals at that stage being able to contribute towards individual fitness and the probability of their surviving to that stage. Complete reproductive cessation and a long post-reproductive female lifespan as found in humans are also found in killer whale (Orcinus orca) and short-finned pilot whale (Globicephala macrorhynchus), but not in the long-finned pilot whale (Globicephala melaena). Each species forms kin-based, stable matrilineal groups and exhibits kin-directed behaviours that could increase inclusive fitness. Here, the initial mortality rate and mortality rate-doubling time of females of these three closely related whale species are compared. The initial mortality rate shows little variation among pilot whale species; however mortality rate accelerates almost twice as fast in the long-finned pilot whale as it does in killer whale and short-finned pilot whale. Selection for a long post-reproductive female lifespan in matrilineal whales may therefore be determined by the proportion of females surviving past the point of reproductive cessation. PMID:18252662

  7. TROPHIC STRUCTURE, REPRODUCTIVE SUCCESS, AND GROWTH RATE OF FISHES IN A NATURAL AND MODIFIED HEADWATER STREAM

    EPA Science Inventory

    The impact of removing riparian vegetation, channel straightening, and fluctuations in flow regime on trophic structure, reproductive success, and growth rate of fishes was assessed in a natural (Jordan Creek(JC)) and modified (Big Ditch(BD)) headwater stream in eastcentral Illin...

  8. Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus).

    PubMed

    French, Susannah S; González-Suárez, Manuela; Young, Julie K; Durham, Susan; Gerber, Leah R

    2011-01-01

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. PMID:21436887

  9. Human Disturbance Influences Reproductive Success and Growth Rate in California Sea Lions (Zalophus californianus)

    PubMed Central

    French, Susannah S.; González-Suárez, Manuela; Young, Julie K.; Durham, Susan; Gerber, Leah R.

    2011-01-01

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. PMID:21436887

  10. Pollen flow and effects of population structure on selfing rates and female and male reproductive success in fragmented Magnolia stellata populations

    PubMed Central

    2013-01-01

    Background Fragmentation of plant populations may affect mating patterns and female and male reproductive success. To improve understanding of fragmentation effects on plant reproduction, we investigated the pollen flow patterns in six adjacent local populations of Magnolia stellata, an insect-pollinated, threatened tree species in Japan, and assessed effects of maternal plant (genet) size, local genet density, population size and neighboring population size on female reproductive success (seed production rates), and effects of mating distance, paternal genet size, population size and separation of populations on male reproductive success. Results The seed production rate, i.e. the proportion of ovules that successfully turned into seeds, varied between 1.0 and 6.5%, and increased with increasing population size and neighboring population size, and with decreasing maternal genet size and local genet density. The selfing rate varied between 3.6 and 28.9%, and increased with increasing maternal genet size and with declining local genet density. Male reproductive success increased with increasing paternal genet size, and decreased with increasing mating distance and separation of population. Pollen flow between the populations was low (6.1%) and highly leptocurtic. Conclusions Our results indicate that habitat fragmentation, separation and reduced size of populations, affected mating patterns and reproductive success of M. stellata. Local competition for pollinators and plant display size were likely to alter the reproductive success. PMID:23517612

  11. Evidence for ASD recurrence rates and reproductive stoppage from large UK ASD research family databases.

    PubMed

    Wood, Claire L; Warnell, Frances; Johnson, Mary; Hames, Annette; Pearce, Mark S; McConachie, Helen; Parr, Jeremy R

    2015-02-01

    Following a diagnosis of a developmental disorder such as autism spectrum disorder (ASD) in early childhood, parents may decide to have fewer children than previously planned. The tendency for families to halt reproduction after receiving a diagnosis for one child is known as reproductive stoppage. Stoppage may lead to an underestimate of recurrence risk estimates of parents having more than one child with ASD. Using two large UK ASD family databases, we investigated recurrence rates for ASD and evidence for reproductive stoppage for both ASD and undiagnosed ASD/broader autism phenotype in a subgroup of families. Reproductive stoppage was tested for using the Mann-Whitney U-test to disprove the null hypothesis that affected and nonaffected children were distributed randomly by birth order. Dahlberg's later-sib method was used to estimate recurrence risk and take stoppage into account. Data were available from 299 families (660 children) including 327 with ASD. Ten percent of the complete families had more than one child with an ASD. Using Dahlberg's later-sib method, the recurrence risk for ASD was 24.7% overall and 50.0% in families with two or more older siblings with ASD. Children with ASD were born significantly later in families than those without ASD in all sibship combinations. This study shows strong evidence that ASD is associated with reproductive stoppage. These data have important implications for family planning and genetic counseling. PMID:25273900

  12. Cyclic variations in nitrogen uptake rate in soybean plants: uptake during reproductive growth

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Raper, C. D. Jr; Henry, L. T.; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Net uptake of NO3- by non-nodulated soybean plants [Glycine max (L.) Merr. cv. Ransom] growing in flowing hydroponic culture was measured daily during a 63 d period of reproductive development between the first florally inductive photoperiod and [unknown word] seed growth. Removal of NO3- from a replenished solution containing 1.0 mol m-3 NO3- was determined by ion chromatography. Uptake of NO3- continued throughout reproductive development. The net uptake rate of NO3- cycled between maxima and minima with a periodicity of oscillation of 3 to 7 d during the floral stage and about 6 d during the fruiting stage. Coupled with increasing concentrations of carbon and C : N ratios in tissues, the oscillations in net uptake rates of NO3- are evidence that the demand for carbohydrate by reproductive organs is contingent on the availability of nitrogen in the shoot pool rather than that the demand for nitrogen follows the flux of carbohydrate into reproductive tissues.

  13. Reproductive aging in captive and wild common chimpanzees: factors influencing the rate of follicular depletion.

    PubMed

    Atsalis, Sylvia; Videan, Elaine

    2009-04-01

    We examine and discuss evidence of contrasting differences in fertility patterns between captive and wild female chimpanzees, Pan troglodytes, as they age; in the wild females reproduce in their 40s, but captive studies suggest that menopause occurs around that time. Thus, despite the increased longevity generally observed in captive populations reproductive life span is shortened. We outline a hypothesis to explain the apparent differential pace of reproductive decline observed between wild and captive populations. The breeding schedules of captive primates may contribute to accelerated reproductive senescence because continuous cycling in captive animals results in early depletion of the ovarian stock and premature senescence. Available evidence supports the hypothesis that women with patterns of high oocyte loss experience earlier menopause. Chimpanzees in captivity live longer, and thus, similar to humans, they may experience follicular depletion that precedes death by many years. In captivity, chimpanzees typically have an early age at menarche and first birth, shorter interbirth intervals associated with short lactational periods as young mature faster, and nursery rearing, which allows mothers to begin cycling earlier. Variables typical of wild chimpanzee populations, including late age at menarche and first birth, long interbirth intervals associated with prolonged lactational periods, and a long period of female infertility after immigration, spare ovulations and may be responsible for the later age at reproductive termination. Finally, we describe and discuss the timing of specific reproductive landmarks that occur as female chimpanzees age, distinguishing between functional menopause (age at last birth) and operational menopause (end of cycling). PMID:19067363

  14. Population trend of the Yellowstone grizzly bear as estimated from reproductive and survival rates

    USGS Publications Warehouse

    Eberhardt, L. L.; Blanchard, B. M.; Knight, R. R.

    1993-01-01

    The trend of the Yellowstone grizzly bear (Ursus arctos horribilis) population was estimated using reproductive rates calculated from 22 individual females and survival rates from 400 female bear-years. The point estimate of the rate of increase was 4.6%, with 95% confidence limits of 0 and 9%. Caution in interpreting this result is advised because of possible biases in the population parameter estimates. The main prospects for improving present knowledge of the population trend appear to be further study of possible biases in the parameter estimates, and the continued use of radiotelemetry to increase the number of samples on which the estimates are based.

  15. Reproductive hazards among workers at high voltage substations

    SciTech Connect

    Nordstroem, S.; Birke, E.; Gustavsson, L.

    1983-01-01

    A retrospective study on reproductive hazards was performed among 542 employees at Swedish power plants. Questionnaires were answered by 89% of the employees. Data on pregnancies were checked by studying hospital case records. There was a statistically significant, decreased frequency of ''normal'' pregnancy outcome, almost exclusively due to an increased frequency of congenital malformations, when the father was a high-voltage switchyard worker. The differences in pregnancy outcome could not be explained by any of the confounding factors analyzed. The total number of children with malformations (26) and the total number of pregnancies in this study, however, were very small.

  16. High Data Rate Instrument Study

    NASA Technical Reports Server (NTRS)

    Schober, Wayne; Lansing, Faiza; Wilson, Keith; Webb, Evan

    1999-01-01

    The High Data Rate Instrument Study was a joint effort between the Jet Propulsion Laboratory (JPL) and the Goddard Space Flight Center (GSFC). The objectives were to assess the characteristics of future high data rate Earth observing science instruments and then to assess the feasibility of developing data processing systems and communications systems required to meet those data rates. Instruments and technology were assessed for technology readiness dates of 2000, 2003, and 2006. The highest data rate instruments are hyperspectral and synthetic aperture radar instruments which are capable of generating 3.2 Gigabits per second (Gbps) and 1.3 Gbps, respectively, with a technology readiness date of 2003. These instruments would require storage of 16.2 Terebits (Tb) of information (RF communications case of two orbits of data) or 40.5 Tb of information (optical communications case of five orbits of data) with a technology readiness date of 2003. Onboard storage capability in 2003 is estimated at 4 Tb; therefore, all the data created cannot be stored without processing or compression. Of the 4 Tb of stored data, RF communications can only send about one third of the data to the ground, while optical communications is estimated at 6.4 Tb across all three technology readiness dates of 2000, 2003, and 2006 which were used in the study. The study includes analysis of the onboard processing and communications technologies at these three dates and potential systems to meet the high data rate requirements. In the 2003 case, 7.8% of the data can be stored and downlinked by RF communications while 10% of the data can be stored and downlinked with optical communications. The study conclusion is that only 1 to 10% of the data generated by high data rate instruments will be sent to the ground from now through 2006 unless revolutionary changes in spacecraft design and operations such as intelligent data extraction are developed.

  17. Divergent selection on, but no genetic conflict over, female and male timing and rate of reproduction in a human population

    PubMed Central

    Bolund, Elisabeth; Bouwhuis, Sandra; Pettay, Jenni E.; Lummaa, Virpi

    2013-01-01

    The sexes often have different phenotypic optima for important life-history traits, and because of a largely shared genome this can lead to a conflict over trait expression. In mammals, the obligate costs of reproduction are higher for females, making reproductive timing and rate especially liable to conflict between the sexes. While studies from wild vertebrates support such sexual conflict, it remains unexplored in humans. We used a pedigreed human population from preindustrial Finland to estimate sexual conflict over age at first and last reproduction, reproductive lifespan and reproductive rate. We found that the phenotypic selection gradients differed between the sexes. We next established significant heritabilities in both sexes for all traits. All traits, except reproductive rate, showed strongly positive intersexual genetic correlations and were strongly genetically correlated with fitness in both sexes. Moreover, the genetic correlations with fitness were almost identical in men and women. For reproductive rate, the intersexual correlation and the correlation with fitness were weaker but again similar between the sexes. Thus, in this population, an apparent sexual conflict at the phenotypic level did not reflect an underlying genetic conflict over the studied reproductive traits. These findings emphasize the need for incorporating genetic perspectives into studies of human life-history evolution. PMID:24107531

  18. Influence of early pregnancy on reproductive rate in lines of mice selected for litter size.

    PubMed

    Eisen, E J

    1980-09-01

    The influence of male-induced early puberty on female reproductive rate was determined in three lines of mice differing in litter size and body weight. The lines originated from a single base population and had undergone 20 generations of selection for the following criteria: large litter size at birth (L(+)), large litter size and small 6-week body weight (L(+)W(-)), or small litter size and large 6-week body weight (L(-)W(+)). Females were paired with a mature intact male of the same line at 3, 5 or 7 weeks of age. Mean mating age, averaged over lines, was 26.5 ± .3, 38.3 ± .3 and 52.7 ± .3 days. Exposure to a mature male accelerated female sexual maturation in each line. When contrasted with their sibs mated at a later age, early-pregnant females from each line exhibited a decline in one or more component of reproductive performance, suggesting that the physiological state of the very young female was not optimum for normal pregnancy. In comparisons of early and later mating ages, all three lines showed a decreased littering rate at first mating, number born alive, and individual birth weight of progeny adjusted for litter size; L(+) and L(+)W(-) mice showed an increased perinatal mortality rate; L(+) and L(-)W(+) had a reduction in litter size at birth. When the L(+), L(+)W(-) and L(-)W(+) lines were compared with an unselected strain and a line selected for high postweaning gain in similar experiments, a genotype by environment interaction was apparent since all lines did not respond in a similar manner to early mating. The line ranking for litter size at birth for each age at male-exposure was L(+)>L(+)W(-)>L(-)W(+), despite the significant line by age interaction. When litter size was adjusted by covariance for body weight at mating, the significant effects of age at male-exposure and line by age interaction were eliminated. All fertile females were remated after they had weaned their first litter to obtain information on litter size in parity two. Line

  19. Reproductive ecology of tree swallows (Tachycineta bicolor) with high levels of polychlorinated biphenyl contamination

    SciTech Connect

    McCarty, J.P.; Secord, A.L.

    1999-07-01

    Tree swallows(Tachycineta bicolor) breeding along the Hudson River forage extensively on PCB-contaminated insects that emerge from the river. The authors studied the reproductive ecology and behavior of tree swallows breeding at several sites along the Hudson River. Related work has shown that PCB levels in both eggs and chicks were among the highest ever reported in this species, with concentrations comparable to those found in aquatic organisms in the Hudson River. In 1994, reproductive success at PCB-contaminated sites was significantly impaired relative to other sites in New York. Reduced reproductive success was largely due to high levels of nest abandonment during incubation and reduced hatchability of eggs. In 1995, reproductive output was normal, but higher than expected rates of abandonment and supernormal clutches persisted. Growth and development of nestlings was not significantly impaired. Given the levels of contamination in this population, the success of most Hudson River tree swallows reinforces the importance of understanding interspecific differences in the effects of contaminants.

  20. Highly variable reproductive isolation among pairs of Catostomus species.

    PubMed

    Mandeville, Elizabeth G; Parchman, Thomas L; McDonald, David B; Buerkle, C Alex

    2015-04-01

    Hybridization between diverged taxa tests the strength of reproductive isolation and can therefore reveal mechanisms of reproductive isolation. However, it remains unclear how consistent reproductive isolation is across species' ranges and to what extent reproductive isolation might remain polymorphic as species diverge. To address these questions, we compared outcomes of hybridization across species pairs of Catostomus fishes in three rivers in the Upper Colorado River basin, where an introduced species, C. commersoni, hybridizes with at least two native species, C. discobolus and C. latipinnis. We observed substantial heterogeneity in outcomes of hybridization, both between species pairs and across geographically separate rivers within each species pair. We also observed hybridization of additional related species with our focal species, suggesting that reproductive isolation in this group involves interactions of multiple evolutionary and ecological factors. These findings suggest that a better understanding of the determinants of variation in reproductive isolation is needed and that studies of reproductive isolation in hybrids should consider how the dynamics and mechanisms of reproductive isolation vary over ecological space and over evolutionary time. Our results also have implications for the conservation and management of native catostomids in the Colorado River basin. Heterogeneity in outcomes of hybridization suggests that the threat posed by hybridization and genetic introgression to the persistence of native species probably varies with extent of reproductive isolation, both across rivers and across species pairs. PMID:25703195

  1. Highly variable reproductive isolation among pairs of Catostomus species

    PubMed Central

    Mandeville, Elizabeth G.; Parchman, Thomas L.; McDonald, David B.; Buerkle, C. Alex

    2015-01-01

    Hybridization between diverged taxa tests the strength of reproductive isolation, and can therefore reveal mechanisms of reproductive isolation. However, it remains unclear how consistent reproductive isolation is across species’ ranges, and to what extent reproductive isolation might remain polymorphic as species diverge. To address these questions, we compared outcomes of hybridization across species pairs of Catostomus fishes in three rivers in the Upper Colorado River basin, where an introduced species, C. commersoni, hybridizes with at least two native species, C. discobolus and C. lattipinis. We observed substantial heterogeneity in outcomes of hybridization, both between species pairs and across geographically separate rivers within each species pair. We also observed hybridization of additional related species with our focal species, suggesting that reproductive isolation in this group involves interactions of multiple evolutionary and ecological factors. These findings suggest that a better understanding of the determinants of variation in reproductive isolation is needed, and that studies of reproductive isolation in hybrids should consider how the dynamics and mechanisms of reproductive isolation vary over ecological space and over evolutionary time. Our results also have implications for the conservation and management of native catostomids in the Colorado River basin. Heterogeneity in outcomes of hybridization suggests that the threat posed by hybridization and genetic introgression to the persistence of native species likely varies with extent of reproductive isolation, both across rivers and across species pairs. PMID:25703195

  2. Effect of Embryo Banking on U.S. National Assisted Reproductive Technology Live Birth Rates

    PubMed Central

    Kushnir, Vitaly A.; Barad, David H.; Albertini, David F.; Darmon, Sarah K.; Gleicher, Norbert

    2016-01-01

    Background Assisted Reproductive Technology (ART) reports generated by the Centers for Disease Control and Prevention (CDC) exclude embryo banking cycles from outcome calculations. Methods We examined data reported to the CDC in 2013 for the impact of embryo banking exclusion on national ART outcomes by recalculating autologous oocyte ART live birth rates. Inflation of reported fresh ART cycle live birth rates was assessed for all age groups of infertile women as the difference between fresh cycle live births with reference to number of initiated fresh cycles (excluding embryo banking cycles), as typically reported by the CDC, and fresh cycle live births with reference to total initiated fresh ART cycles (including embryo banking cycles). Results During 2013, out of 121,351 fresh non-donor ART cycles 27,564 (22.7%) involved embryo banking. The proportion of banking cycles increased with female age from 15.5% in women <35 years to 56.5% in women >44 years. Concomitantly, the proportion of thawed cycles decreased with advancing female age (P <0.0001). Exclusion of embryo banking cycles led to inflation of live birth rates in fresh ART cycles, increasing in size in parallel to advancing female age and utilization of embryo banking, reaching 56.3% in women age >44. The inflation of live birth rates in thawed cycles could not be calculated from the publically available CDC data but appears to be even greater. Conclusions Utilization of embryo banking increased during 2013 with advancing female age, suggesting a potential age selection bias. Exclusion of embryo banking cycles from national ART outcome reports significantly inflated national ART success rates, especially among older women. Précis Exclusion of embryo banking cycles from US National Assisted Reproductive Technology outcome reports significantly inflates reported success rates especially in older women. PMID:27159215

  3. High rate manure supernatant digestion.

    PubMed

    Bergland, Wenche Hennie; Dinamarca, Carlos; Toradzadegan, Mehrdad; Nordgård, Anna Synnøve Røstad; Bakke, Ingrid; Bakke, Rune

    2015-06-01

    The study shows that high rate anaerobic digestion may be an efficient way to obtain sustainable energy recovery from slurries such as pig manure. High process capacity and robustness to 5% daily load increases are observed in the 370 mL sludge bed AD reactors investigated. The supernatant from partly settled, stored pig manure was fed at rates giving hydraulic retention times, HRT, gradually decreased from 42 to 1.7 h imposing a maximum organic load of 400 g COD L(-1) reactor d(-1). The reactors reached a biogas production rate of 97 g COD L(-1) reactor d(-1) at the highest load at which process stress signs were apparent. The yield was ∼0.47 g COD methane g(-1) CODT feed at HRT above 17 h, gradually decreasing to 0.24 at the lowest HRT (0.166 NL CH4 g(-1) CODT feed decreasing to 0.086). Reactor pH was innately stable at 8.0 ± 0.1 at all HRTs with alkalinity between 9 and 11 g L(-1). The first stress symptom occurred as reduced methane yield when HRT dropped below 17 h. When HRT dropped below 4 h the propionate removal stopped. The yield from acetate removal was constant at 0.17 g COD acetate removed per g CODT substrate. This robust methanogenesis implies that pig manure supernatant, and probably other similar slurries, can be digested for methane production in compact and effective sludge bed reactors. Denaturing gradient gel electrophoresis (DGGE) analysis indicated a relatively fast adaptation of the microbial communities to manure and implies that non-adapted granular sludge can be used to start such sludge bed bioreactors. PMID:25776915

  4. Individualised controlled ovarian stimulation (iCOS): maximising success rates for assisted reproductive technology patients

    PubMed Central

    2011-01-01

    Background In the last two decades, pregnancy rates for patients undergoing in-vitro fertilisation (IVF) have significantly increased. Some of the major advances responsible for this improvement were the introduction of controlled ovarian stimulation (COS) for the induction of multiple follicle development, and the utilisation of mid-luteal gonadotropin-releasing hormone agonists to achieve pituitary down-regulation and full control of the cycle. As a result, a combination of a gonadotropin-releasing hormone agonist with high doses (150-450 IU/day) of recombinant follicle-stimulating hormone has become the current standard approach for ovarian stimulation. However, given the heterogeneity of patients embarking on IVF, and the fact that many different drugs can be used alone or in different combinations (generating multiple potential protocols of controlled ovarian stimulation), we consider the need to identify special populations of patients and adapt treatment protocols accordingly, and to implement a more individualised approach to COS. Discussion Studies on mild, minimal and natural IVF cycles have yielded promising results, but have focused on fresh embryo transfers and included relatively young patient populations who generally have the potential for more favourable outcomes. The efficacy of these protocols in patients with a poorer prognosis remains to be tested. When comparing protocols for COS, it is important to think beyond current primary endpoints, and to consider the ideal quality and quantity of oocytes and embryos being produced per stimulated patient, in order to achieve a pregnancy. We should also focus on the cumulative pregnancy rate, which is based on outcomes from fresh and frozen embryos from the same cycle of stimulation. Individualised COS (iCOS) determined by the use of biomarkers to test ovarian reserve has the potential to optimise outcomes and reduce safety issues by adapting treatment protocols according to each patient's specific

  5. Semen cryopreservation and usage rate for assisted reproductive technology in 898 men with cancer.

    PubMed

    Muller, Iris; Oude Ophuis, Ralph J A; Broekmans, Frank J M; Lock, Tycho M T W

    2016-02-01

    An undesired side effect of cancer treatment is potential subfertility or infertility. Timely cryopreservation of semen is the best modality to ensure fertility. This retrospective data analysis established the usage rate of cryopreserved semen from cancer patients. Pubertal and post-pubertal patients who could become infertile as a result of cancer (treatment) were offered the option to cryopreserve semen prior to treatment. Of the 898 patients who cryopreserved their semen in our hospital, 96 (10.7%) used this for assisted reproductive technology. The live birth rates for intrauterine insemination, in-vitro fertilization, intracytoplasmic sperm injection and cryopreserved embryo transfer were 13%, 29%, 32% and 17%, respectively. Of all couples involved, 77% achieved parenthood, i.e. 60 of the 78 patients (with complete follow-up) fathered at least one child. PMID:26687904

  6. High Resolution, High Frame Rate Video Technology

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Papers and working group summaries presented at the High Resolution, High Frame Rate Video (HHV) Workshop are compiled. HHV system is intended for future use on the Space Shuttle and Space Station Freedom. The Workshop was held for the dual purpose of: (1) allowing potential scientific users to assess the utility of the proposed system for monitoring microgravity science experiments; and (2) letting technical experts from industry recommend improvements to the proposed near-term HHV system. The following topics are covered: (1) State of the art in the video system performance; (2) Development plan for the HHV system; (3) Advanced technology for image gathering, coding, and processing; (4) Data compression applied to HHV; (5) Data transmission networks; and (6) Results of the users' requirements survey conducted by NASA.

  7. High accuracy optical rate sensor

    NASA Technical Reports Server (NTRS)

    Uhde-Lacovara, J.

    1990-01-01

    Optical rate sensors, in particular CCD arrays, will be used on Space Station Freedom to track stars in order to provide inertial attitude reference. An algorithm to provide attitude rate information by directly manipulating the sensor pixel intensity output is presented. The star image produced by a sensor in the laboratory is modeled. Simulated, moving star images are generated, and the algorithm is applied to this data for a star moving at a constant rate. The algorithm produces accurate derived rate of the above data. A step rate change requires two frames for the output of the algorithm to accurately reflect the new rate. When zero mean Gaussian noise with a standard deviation of 5 is added to the simulated data of a star image moving at a constant rate, the algorithm derives the rate with an error of 1.9 percent at a rate of 1.28 pixels per frame.

  8. Reproductive toxicity in male mice after exposure to high molybdenum and low copper concentrations.

    PubMed

    Wang, Hong-Wei; Zhou, Bian-Hua; Zhang, Sen; Guo, Hong-Wei; Zhang, Ji-Liang; Zhao, Jing; Tian, Er-Jie

    2016-09-01

    To evaluate the effects of dietary high molybdenum (HMo) and low copper (LCu) concentrations on reproductive toxicity of male mice, 80 mice were divided into 4 groups of 20. These groups were fed with the following: (1) normal control (NC) diet (NC group); (2) NC and HMo diets (HMo group); (3) LCu diet (LCu group); and (4) HMo and LCu diets (HMoLCu group). On the 50th and 100th day, superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) were analyzed to determine oxidative stress states. Morphological changes in testicular tissue were evaluated with hematoxylin and eosin staining and ultrastructural changes were monitored by transmission electron microscopy. The results showed that administration of HMo, LCu, and HMoLCu not only decreased sperm density and motility but also increased the rate of teratosperm occurrence. A significant increase in MDA content and a decrease in SOD, GSH-Px, and T-AOC contents were observed in LCu, HMo, and HMoLCu groups. Testicular tissues and cells of mice were damaged by HMo and the damages were more serious in the case of Cu deficiency. Exposure to HMo adversely affected the reproductive system of male mice, and dietary LCu plays key roles in HMo-induced reproductive toxicity. PMID:25691499

  9. Faster reproductive rates trade off against offspring growth in wild chimpanzees.

    PubMed

    Emery Thompson, Melissa; Muller, Martin N; Sabbi, Kris; Machanda, Zarin P; Otali, Emily; Wrangham, Richard W

    2016-07-12

    Life history theory predicts a trade-off between offspring quality and quantity. Among large-bodied mammals, prolonged lactation and infant dependence suggest particularly strong potential for a quality-quantity trade-off to exist. Humans are one of the only such species to have been examined, providing mixed evidence under a peculiar set of circumstances, including extensive nutritional provisioning by nonmothers and extrasomatic wealth transmission. Here, we examine trade-offs between reproductive rate and one aspect of offspring quality (body size) in wild chimpanzees (Pan troglodytes schweinfurthii), a species with long periods of infant dependence and little direct provisioning. Juvenile lean body mass, estimated using urinary creatinine excretion, was positively associated with the interval to the next sibling's birth. These effects persisted into adolescence and were not moderated by maternal identity. Maternal depletion could not explain poor offspring growth, as older mothers had larger offspring, and low maternal energy balance during lactation predicted larger, not smaller, juvenile size. Instead, our data suggest that offspring growth suffers when mothers wean early to invest in new reproductive efforts. These findings indicate that chimpanzee mothers with the resources to do so prioritize production of new offspring over prolonged investment in current offspring. PMID:27354523

  10. Highly pathogenic porcine reproductive and respiratory syndrome virus JXwn06 causes high mortality in vivo

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006, a large-scale outbreak of highly pathogenic atypical porcine reproductive and respiratory syndrome virus (PRRSV) spread throughout the swine population in China. Causative PRRSV isolates were characterized genetically by a unique 30aa deletion in PRRSV nonstructural protein 2 and clinically...

  11. An Alternative Model of the Reproductive Rate of HIV Infection: Formulation, Evaluation, and Implications for Risk Reduction Interventions.

    ERIC Educational Resources Information Center

    Pinkerton, Steven D.; Abramson, Paul R.

    1994-01-01

    Estimates of the reproductive rate of infection with the human immunodeficiency virus (HIV), obtained through a Bernoulli process model, indicate that decreasing the infectivity of the virus, through the use of condoms, for example, is more effective at reducing the infection rate than is limiting the number of sexual partners. (SLD)

  12. Effects of intraspecific variation in reproductive traits, pectoral fin use and burst swimming on metabolic rates and swimming performance in the Trinidadian guppy (Poecilia reticulata).

    PubMed

    Svendsen, Jon C; Banet, Amanda I; Christensen, Rune H B; Steffensen, John F; Aarestrup, Kim

    2013-09-15

    There is considerable intraspecific variation in metabolic rates and locomotor performance in aquatic ectothermic vertebrates; however, the mechanistic basis remains poorly understood. Using pregnant Trinidadian guppies (Poecilia reticulata), a live-bearing teleost, we examined the effects of reproductive traits, pectoral fin use and burst-assisted swimming on swimming metabolic rate, standard metabolic rate (O2std) and prolonged swimming performance (Ucrit). Reproductive traits included reproductive allocation and pregnancy stage, the former defined as the mass of the reproductive tissues divided by the total body mass. Results showed that the metabolic rate increased curvilinearly with swimming speed. The slope of the relationship was used as an index of swimming cost. There was no evidence that reproductive traits correlated with swimming cost, O2std or Ucrit. In contrast, data revealed strong effects of pectoral fin use on swimming cost and Ucrit. Poecilia reticulata employed body-caudal fin (BCF) swimming at all tested swimming speeds; however, fish with a high simultaneous use of the pectoral fins exhibited increased swimming cost and decreased Ucrit. These data indicated that combining BCF swimming and pectoral fin movement over a wide speed range, presumably to support swimming stability and control, is an inefficient swimming behaviour. Finally, transition to burst-assisted swimming was associated with an increase in aerobic metabolic rate. Our study highlights factors other than swimming speed that affect swimming cost and suggests that intraspecific diversity in biomechanical performance, such as pectoral fin use, is an important source of variation in both locomotor cost and maximal performance. PMID:23737561

  13. Low reproductive performance and high sow mortality in a pig breeding herd: a case study.

    PubMed

    Rueda López, Ma

    2008-01-01

    Sow performance is a key component of the productivity of commercial pig farms. Reproductive failure in the sow is common in pig production. For every 100 sows served, 89 should farrow. In absence of specific diseases such as porcine parvovirus, pseudo-rabies, swine fever, leptospirosis and brucellosis, management failures are the most important causes of loss. A syndrome associated with reproductive inefficiency, and post-service vaginal discharge and high sow mortality in a commercial pig farm is described. Pregnancy failures exceeded 20% and sow mortality exceeded 12% for two consecutive years. The abnormal post-service vaginal discharge rate was 1.7% during the period of investigation.An investigation involving an analysis of farm records, a review of breeding management practices, clinical examinations, laboratory analysis and examination of urogenital organs was conducted.The main contributing factors found were a sub-optimal gilt breeding management, an inadequate culling policy in combination with a sub-optimal culling rate and the presence of cystitis in more than 1% of the urogenital organs examined. The high sow mortality rate was related to an aged breeding herd.A control programme was recommended based on management changes involving oestrus detection, movement of gilts post-service, hygiene in the service area, boar exposure post-service and urinary acidification. This programme failed to increase the farrowing rate due to incomplete implementation of the recommendations made. The farrowing rate increased to 86.5% subsequent to a farm manager change in January 2005, which resulted in complete implementation of the control programme. PMID:21851706

  14. Low reproductive performance and high sow mortality in a pig breeding herd: a case study

    PubMed Central

    2008-01-01

    Sow performance is a key component of the productivity of commercial pig farms. Reproductive failure in the sow is common in pig production. For every 100 sows served, 89 should farrow. In absence of specific diseases such as porcine parvovirus, pseudo-rabies, swine fever, leptospirosis and brucellosis, management failures are the most important causes of loss. A syndrome associated with reproductive inefficiency, and post-service vaginal discharge and high sow mortality in a commercial pig farm is described. Pregnancy failures exceeded 20% and sow mortality exceeded 12% for two consecutive years. The abnormal post-service vaginal discharge rate was 1.7% during the period of investigation. An investigation involving an analysis of farm records, a review of breeding management practices, clinical examinations, laboratory analysis and examination of urogenital organs was conducted. The main contributing factors found were a sub-optimal gilt breeding management, an inadequate culling policy in combination with a sub-optimal culling rate and the presence of cystitis in more than 1% of the urogenital organs examined. The high sow mortality rate was related to an aged breeding herd. A control programme was recommended based on management changes involving oestrus detection, movement of gilts post-service, hygiene in the service area, boar exposure post-service and urinary acidification. This programme failed to increase the farrowing rate due to incomplete implementation of the recommendations made. The farrowing rate increased to 86.5% subsequent to a farm manager change in January 2005, which resulted in complete implementation of the control programme. PMID:21851706

  15. Elephants born in the high stress season have faster reproductive ageing

    PubMed Central

    Mumby, Hannah S.; Mar, Khyne U.; Hayward, Adam D.; Htut, Win; Htut-Aung, Ye; Lummaa, Virpi

    2015-01-01

    Senescent declines in reproduction and survival are found across the tree of life, but little is known of the factors causing individual variation in reproductive ageing rates. One contributor may be variation in early developmental conditions, but only a few studies quantify the effects of early environment on reproductive ageing and none concern comparably long-lived species to humans. We determine the effects of ‘stressful’ birth conditions on lifetime reproduction in a large semi-captive population of Asian elephants (Elephas maximus). We categorise birth month into stressful vs. not-stressful periods based on longitudinal measures of glucocorticoid metabolites in reproductive-aged females, which peak during heavy workload and the start of the monsoon in June-August. Females born in these months exhibit faster reproductive senescence in adulthood and have significantly reduced lifetime reproductive success than their counterparts born at other times of year. Improving developmental conditions could therefore delay reproductive ageing in species as long-lived as humans. PMID:26365592

  16. Effects of subcutaneous transmitters on reproduction, incubation behavior, and annual return rates of female wood ducks

    USGS Publications Warehouse

    Hepp, G.R.; Folk, T.H.; Hartke, K.M.

    2002-01-01

    Radiotransmitters attached externally to breeding waterfowl can have a variety of negative effects. Implanted transmitters can reduce potential deleterious effects; abdominal implants are used most commonly in waterfowl. Methods also have been developed to implant transmitters subcutaneously, but effects of subcutaneous implants on adult ducks have not been evaluated. In this study, we subcutaneously implanted radiotransmitters in pre-laying female wood ducks (Aix sponsa, n = 62) and compared nest initiation date, incubation behavior, body mass, and annual return rates of radiomarked females to a group of females that were not radiomarked. Ninety-six percent (50 of 52) of radiomarked females that were monitored for the entire breeding season initiated nests. Nesting date of radiomarked adult females did not differ from that of adult females without radios, but radiomarked yearling females nested earlier than yearlings not receiving transmitters. We found no differences in early- and late-incubation body mass, incubation constancy, recess frequency, and incubation period between radiomarked females and those without radios. Annual return rates of females that initiated nests did not differ between radiomarked females and those not receiving radios. Data suggest that implanting radiotransmitters subcutaneously in pre-laying female wood ducks did not negatively impact subsequent reproduction, incubation behavior, and survival.

  17. High juvenile hormone titre and abdominal activation of JH signalling may induce reproduction of termite neotenics.

    PubMed

    Saiki, R; Gotoh, H; Toga, K; Miura, T; Maekawa, K

    2015-08-01

    Termite castes are a key example of polyphenism, in which reproductive division of labour is clearly seen in colonies. The reproductive castes in termites include primary and neotenic reproductives; primary reproductives found a new colony whereas neotenics succeed them in the reproductive role when the primary reproductives die or become senescent. Neotenics usually differentiate from nymphs or workers by developing functional gonads while retaining juvenile characteristics; however, the developmental mechanism during neotenic differentiation remains poorly understood. Juvenile hormone (JH) mediates a number of aspects of developmental regulation in caste differentiation in termites. In the present study we quantified JH titres in neotenic reproductives of Reticulitermes speratus, and compared these with other developmental stages. In addition, expression changes in JH signalling gene homologues (Methoprene-tolerant [Met], Krüppel-homolog1, Broad-Complex) in the head, thorax and abdomen were investigated during neotenic differentiation. Finally, we examined the function of Met in reproduction of neotenics by RNA interference (RNAi). Our results showed that the JH titres of neotenics were significantly higher than those of nymphs and workers. JH signalling genes were highly expressed in neotenic abdomens, compared with those in workers and nymphs. Met RNAi resulted in the inhibition of vitellogenin gene expression in newly moulted neotenics. These results suggest that the fertility of neotenics might be controlled by a large increase of JH titres and body-part-specific activation of JH signalling pathways. PMID:25847681

  18. Survival rates and lifetime reproduction of breeding male Cooper’s Hawks in Wisconsin, 1980-2005

    USGS Publications Warehouse

    Rosenfield, Robert N.; Bielefeldt, John; Rosenfield, Laura J.; Booms, Travis L.; Bozek, Michael A.

    2009-01-01

    There are few published data on annual survival and no reports of lifetime reproduction for breeding Cooper's Hawks (Accipiter cooperii). Breeding males (n  =  105) in central and southeastern Wisconsin had an annual mortality rate of 19%, or a survival rate of 81% for birds ≤10 years of age. We did not detect significant differences in mortality rates between urban and rural habitats, nor between the earlier 13 years and later 13 years of this study. Male Cooper's Hawks produced from zero to 32 nestlings during their lifetimes. Body mass or size appeared unrelated to annual survivorship and lifetime reproduction, although lifetime reproduction was correlated strongly with longevity of breeding males. Fifteen of 66 males (23%) produced most (53%) of the nestlings. Our studies occurred in an area where breeding populations may be increasing with some of the highest reported productivity indices and nesting densities for this species. Habitat used for nesting on our Wisconsin study areas may be less important for survivorship and lifetime reproduction than acquisition of a nesting area in which a male will breed throughout his life.

  19. Effects of high density on spacing behaviour and reproduction in Akodon azarae: A fencing experiment

    NASA Astrophysics Data System (ADS)

    Ávila, Belén; Bonatto, Florencia; Priotto, José; Steinmann, Andrea R.

    2016-01-01

    We studied the short term spacing behavioural responses of Pampean grassland mouse (Akodon azarae) with regard to population density in four 0.25 ha enclosures (two control and two experimental) in the 2011 breeding season. Based on the hypothesis that A. azarae breeding females exhibit spacing behaviour, and breeding males show a fusion spatial response, we tested the following predictions: (1) home range size and intrasexual overlap degree of females are independent of population density values; (2) at high population density, home range size of males decreases and the intrasexual home range overlap degree increases. To determine if female reproductive success decreases at high population density, we analyzed pregnancy rate, size and weight of litters, and period until fecundation in both low and high enclosure population density. We found that both males and females varied their home range size in relation to population density. Although male home ranges were always bigger than those of females in populations with high density, home range sizes of both sexes decreased. Females kept exclusive home ranges independent of density values meanwhile males decreased home range overlap in high breeding density populations. Although females produced litters of similar size in both treatments, weight of litter, pregnant rate and period until fecundation varied in relation to population density. Our results did not support the hypothesis that at high density females of A. azarae exhibit spacing behaviour neither that males exhibit a fusion spatial response.

  20. Cumulative live birth rate and assisted reproduction: impact of female age and transfer day

    PubMed Central

    Abuzeid, M.I.; Bolonduro, O.; La Chance, J.; Abozaid, T.; Urich, M.; Ullah, K.; Ali, T.; Ashraf, M.; Khan, I.

    2014-01-01

    Background: Many studies on assisted reproductive technology examine live birth rate per cycle. However, after a cycle fails, couples often want to know what their chances are of having a live birth if they continue treatment. From a patients’ perspective, the cumulative probability of live birth is more informative. Materials and Methods: This study includes patients who underwent fresh, frozen and non-donor ICSI cycles at our IVF unit between 2006-2012. Patients were divided into two groups; Group 1 represented those who underwent only Day 5 transfers, Group 2 represented only Day 3 transfers. Patients who underwent both were excluded. ­Cycles were analyzed until the first live birth or the end of the 3rd cycle. Using Kaplan-Meier analysis, we estimated the cumulative live birth rates for each group and according to female age. Results: The mean age for Group 1 was significantly lower than for Group 2. After 3 cycles, Group 1’s CLBR was 79% versus 66% in Group 2. When analyzing the live births by age and group, there was a significant difference in the CLBR after 3 cycles with the women less than 35 years having the highest CLBR and the women 40 years or older having the lowest CLBR. Conclusion: In women less than 35 years, excellent CLBR can be achieved irrespective of the transfer day. For women 40 years and above, better results of CLBR are observed with Day 5 transfers. Our findings may impact the counseling of couples considering IVF treatment. PMID:25374657

  1. High variation in clonal vs. sexual reproduction in populations of the wild strawberry, Fragaria virginiana (Rosaceae)

    PubMed Central

    Wilk, John A.; Kramer, Andrea T.; Ashley, Mary V.

    2009-01-01

    Background and Aims Many plants reproduce both clonally and sexually, and the balance between the two modes of reproduction will vary among populations. Clonal reproduction was characterized in three populations of the wild strawberry, Fragaria virginiana, to determine the extent that reproductive mode varied locally between sites. The study sites were fragmented woodlands in Cook County, Illinois, USA. Methods A total of 95 strawberry ramets were sampled from the three sites via transects. Ramets were mapped and genotyped at five variable microsatellite loci. The variability at these five loci was sufficient to assign plants to clones with high confidence, and the spatial pattern of genets was mapped at each site. Key Results A total of 27 distinct multilocus genotypes were identified. Of these, 18 genotypes were detected only once, with the remaining nine detected in multiple ramets. The largest clone was identified in 16 ramets. No genets were shared between sites, and each site exhibited markedly different clonal and sexual recruitment patterns, ranging from two non-overlapping and widespread genets to 19 distinct genets. Only one flowering genet was female; the remainder were hermaphrodites. Conclusions Local population history or fine-scale ecological differences can result in dramatically different reproductive patterns at small spatial scales. This finding may be fairly widespread among clonal plant species, and studies that aim to characterize reproductive modes in species capable of asexual reproduction need to evaluate reproductive modes in multiple populations and sites. PMID:19797422

  2. Effect of dsRNA on growth rate and reproductive potential of Monosporascus cannonballus.

    PubMed

    Armengol, Josep; Alaniz, Sandra; Vicent, Antonio; Beltrán, Roberto; Abad-Campos, Paloma; Pérez-Sierra, Ana; García-Jiménez, José; Ben Salem, Ibtissem; Souli, Mounira; Boughalleb, Naima

    2011-03-01

    The effect of double stranded RNA (dsRNA) infection on growth rate and the reproductive potential of Monosporascus cannonballus was studied in 21 isolates collected in cucurbit growing areas of Spain and Tunisia. The isolates were incubated on potato dextrose agar (PDA) under different conditions of temperature, pH, and water potential (Ψ(s)). They showed optimal growth temperatures over the range of 27-34°C and perithecia formation was obtained mainly at 25 and 30°C, although some isolates were able to produce perithecia at 35°C. All isolates were able to produce perithecia in a broad range of pHs (4-8). Regarding the effect of Ψ(s,) the isolates were more tolerant to grow on KCl than on NaCl. For each solute, radial growth decreased progressively as Ψ(s) decreased and was severely limited at -5.0 to -6.0MPa. Perithecia formation was highest at -0.5MPa, decreased at -1.0MPa and occurred just in some isolates at -2.0MPa. Nine of the M. cannonballus isolates harboured dsRNA with 2-6 bands each and a size range of 1.9-18.0Kb. Phenotypical data were subjected to multivariate factorial analysis. Most of the isolates clustered in two groups corresponding with the presence/absence of dsRNA elements. Isolates without detectable dsRNA produced more perithecia. However, isolates with dsRNA produced lower number of perithecia depending on the pH, Ψ(s,) or solute used. These results improve our understanding of the behaviour and growth of this pathogen in soil, and can be useful to implement effective disease control. PMID:21354530

  3. The dynamics of reproductive rate, offspring survivorship and growth in the lined seahorse, Hippocampus erectus Perry, 1810

    PubMed Central

    Lin, Qiang; Li, Gang; Qin, Geng; Lin, Junda; Huang, Liangmin; Sun, Hushan; Feng, Peiyong

    2012-01-01

    Summary Seahorses are the vertebrate group with the embryonic development occurring within a special pouch in males. To understand the reproductive efficiency of the lined seahorse, Hippocampus erectus Perry, 1810 under controlled breeding experiments, we investigated the dynamics of reproductive rate, offspring survivorship and growth over births by the same male seahorses. The mean brood size of the 1-year old pairs in the 1st birth was 85.4±56.9 per brood, which was significantly smaller than that in the 6th birth (465.9±136.4 per brood) (P<0.001). The offspring survivorship and growth rate increased with the births. The fecundity was positively correlated with the length of brood pouches of males and trunk of females. The fecundity of 1-year old male and 2-year old female pairs was significantly higher than that from 1-year old couples (P<0.001). The brood size (552.7±150.4) of the males who mated with females that were isolated for the gamete-preparation, was larger than those (467.8±141.2) from the long-term pairs (P<0.05). Moreover, the offspring from the isolated females had higher survival and growth rates. Our results showed that the potential reproductive rate of seahorses H. erectus increased with the brood pouch development. PMID:23213429

  4. Extensive Pollen Flow but Few Pollen Donors and High Reproductive Variance in an Extremely Fragmented Landscape

    PubMed Central

    González-Martínez, Santiago C.; Aparicio, Abelardo

    2012-01-01

    Analysing pollen movement is a key to understanding the reproductive system of plant species and how it is influenced by the spatial distribution of potential mating partners in fragmented populations. Here we infer parameters related to levels of pollen movement and diversity of the effective pollen cloud for the wind-pollinated shrub Pistacia lentiscus across a highly disturbed landscape using microsatellite loci. Paternity analysis and the indirect KinDist and Mixed Effect Mating models were used to assess mating patterns, the pollen dispersal kernel, the effective number of males (Nep) and their relative individual fertility, as well as the existence of fine-scale spatial genetic structure in adult plants. All methods showed extensive pollen movement, with high rates of pollen flow from outside the study site (up to 73–93%), fat-tailed dispersal kernels and large average pollination distances (δ = 229–412 m). However, they also agreed in detecting very few pollen donors (Nep = 4.3–10.2) and a large variance in their reproductive success: 70% of males did not sire any offspring among the studied female plants and 5.5% of males were responsible for 50% of pollinations. Although we did not find reduced levels of genetic diversity, the adult population showed high levels of biparental inbreeding (14%) and strong spatial genetic structure (Sp = 0.012), probably due to restricted seed dispersal and scarce safe sites for recruitment. Overall, limited seed dispersal and the scarcity of successful pollen donors can be contributing to generate local pedigrees and to increase inbreeding, the prelude of genetic impoverishment. PMID:23152842

  5. Diversity of reproduction rate supports cooperation in the prisoner's dilemma game on complex networks

    NASA Astrophysics Data System (ADS)

    Szolnoki, A.; Perc, M.; Szabó, G.

    2008-02-01

    In human societies the probability of strategy adoption from a given person may be affected by the personal features. Now we investigate how an artificially imposed restricted ability to reproduce, overruling ones fitness, affects an evolutionary process. For this purpose we employ the evolutionary prisoner's dilemma game on different complex graphs. Reproduction restrictions can have a facilitative effect on the evolution of cooperation that sets in irrespective of particularities of the interaction network. Indeed, an appropriate fraction of less fertile individuals may lead to full supremacy of cooperators where otherwise defection would be widespread. By studying cooperation levels within the group of individuals having full reproduction capabilities, we reveal that the recent mechanism for the promotion of cooperation is conceptually similar to the one reported previously for scale-free networks. Our results suggest that the diversity in the reproduction capability, related to inherently different attitudes of individuals, can enforce the emergence of cooperative behavior among selfish competitors.

  6. Population dynamics of Salpa thompsoni near the Antarctic Peninsula: Growth rates and interannual variations in reproductive activity (1993-2009)

    NASA Astrophysics Data System (ADS)

    Loeb, V. J.; Santora, J. A.

    2012-04-01

    The salp Salpa thompsoni has exhibited increased abundance in high latitude portions of the Southern Ocean in recent decades and is now frequently the numerically dominant zooplankton taxon in the Antarctic Peninsula region. The abundance increase of this species in high latitude waters is believed related to ocean warming. Due to its continuous filter feeding and production of dense rapidly sinking fecal pellets S. thompsoni is considered to be an important link in the export of particulate carbon from the surface waters. Hence basic information on the life history of this component of the Antarctic marine ecosystem is essential for assessing its impact given continued climate warming. Here we cover various aspects of the life history of S. thompsoni collected in the north Antarctic Peninsula during annual austral summer surveys of the US Antarctic Marine Living Resources (AMLR) Program between 1993 and 2009. We focus on seasonal and interannual variations in the size composition and abundance of the aggregate (sexual) and solitary (asexual) stages. This information is valuable for refining components of Southern Ocean food web models that explicitly deal with size-structured and life history information on zooplankton. Intraseasonal changes in length-frequency distribution of both stages are used to estimate their growth rates. These average 0.40 mm day-1 for aggregates and 0.23 mm day-1 for solitaries; together these represent ∼7 week and ∼7.5 month generation times, respectively, and a 9 month life cycle (i.e., onset of aggregate production year 1 to aggregate production year 2). Based on the maximum lengths typically found during January-March, the life spans of the aggregate and solitary stages can reach at least ∼5 and ∼15 months, respectively. Length-frequency distributions each year reflect interannual differences in timing of the initiation and peak reproductive output. Interannual differences in the abundance of total salps and proportions of the

  7. Development, consumption rates and reproductive biology of Orius albidipennis reared on various prey

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The reproductive biology and feeding consumption of Orius albidipennis fed on eggs of Anagasta (Ephestia) kuehniella, Tetranychus urticae, and Trialeurodes vaporariorum, and larvae of Gynaikothrips ficorum were investigated under 26±1°C, 60±10 % RH and 16:8 L/D photoperiod in laboratory. Results ind...

  8. THE INFLUENCE OF MODEL TIME STEP ON THE RELATIVE SENSITIVIY OF POPULATION GROWTH RATE TO REPRODUCTION

    EPA Science Inventory

    In recent years there has been an increasing interest in using population models in environmental assessments. Matrix population models represent a valuable tool for extrapolating from life stage-specific stressor effects on survival and reproduction to effects on finite populati...

  9. Reproductive health risk behavior survey of Colombian high school students.

    PubMed

    Becher, J C; Garcia, J G; Kaplan, D W; Gil, A R; Li, J; Main, D; Herrera, J A; Arias, L; Bromet, A

    1999-03-01

    A survey on the reproductive health risk behaviors of adolescent students in Colombia was conducted. 230 9th and 11th graders participated in a survey using the Centers for Disease Control and Prevention's self-administered Youth Risk Behavior Survey. The sample was composed of 62% females and 38% males, aged 13-18 years. It was found that 29% had engaged in sexual intercourse; among these, 13% were 9th graders and 43% were 11th graders. Increasing age and male gender were significantly correlated with past sexual activity. Older males have more prevalent sexual activity than older females, while younger adolescents showed no gender differences. Male gender was significantly associated with early age of initiation of intercourse. Furthermore, 48% reported using contraception during their last sexual encounter, of which 63% used an effective method (condom, oral contraception, withdrawal) and 37% used a method of low or unknown efficacy. Use of alcohol prior to the last sexual intercourse accounted for 14%. The majority of the participants had discussed or received information on HIV infection at school (92%) or from family (77%). Results showed unmet health needs of the adolescent groups and lower frequency of contraceptive use. PMID:10195806

  10. High burn rate solid composite propellants

    NASA Astrophysics Data System (ADS)

    Manship, Timothy D.

    High burn rate propellants help maintain high levels of thrust without requiring complex, high surface area grain geometries. Utilizing high burn rate propellants allows for simplified grain geometries that not only make production of the grains easier, but the simplified grains tend to have better mechanical strength, which is important in missiles undergoing high-g accelerations. Additionally, high burn rate propellants allow for a higher volumetric loading which reduces the overall missile's size and weight. The purpose of this study is to present methods of achieving a high burn rate propellant and to develop a composite propellant formulation that burns at 1.5 inches per second at 1000 psia. In this study, several means of achieving a high burn rate propellant were presented. In addition, several candidate approaches were evaluated using the Kepner-Tregoe method with hydroxyl terminated polybutadiene (HTPB)-based propellants using burn rate modifiers and dicyclopentadiene (DCPD)-based propellants being selected for further evaluation. Propellants with varying levels of nano-aluminum, nano-iron oxide, FeBTA, and overall solids loading were produced using the HTPB binder and evaluated in order to determine the effect the various ingredients have on the burn rate and to find a formulation that provides the burn rate desired. Experiments were conducted to compare the burn rates of propellants using the binders HTPB and DCPD. The DCPD formulation matched that of the baseline HTPB mix. Finally, GAP-plasticized DCPD gumstock dogbones were attempted to be made for mechanical evaluation. Results from the study show that nano-additives have a substantial effect on propellant burn rate with nano-iron oxide having the largest influence. Of the formulations tested, the highest burn rate was a 84% solids loading mix using nano-aluminum nano-iron oxide, and ammonium perchlorate in a 3:1(20 micron: 200 micron) ratio which achieved a burn rate of 1.2 inches per second at 1000

  11. Multichannel analyzers at high rates of input

    NASA Technical Reports Server (NTRS)

    Rudnick, S. J.; Strauss, M. G.

    1969-01-01

    Multichannel analyzer, used with a gating system incorporating pole-zero compensation, pile-up rejection, and baseline-restoration, achieves good resolution at high rates of input. It improves resolution, reduces tailing and rate-contributed continuum, and eliminates spectral shift.

  12. High-rate lithium thionyl chloride cells

    NASA Technical Reports Server (NTRS)

    Goebel, F.

    1982-01-01

    A high-rate C cell with disc electrodes was developed to demonstrate current rates which are comparable to other primary systems. The tests performed established the limits of abuse beyond which the cell becomes hazardous. Tests include: impact, shock, and vibration tests; temperature cycling; and salt water immersion of fresh cells.

  13. ISS Update: High Rate Communications System

    NASA Video Gallery

    ISS Update Commentator Pat Ryan interviews Diego Serna, Communications and Tracking Officer, about the High Rate Communications System. Questions? Ask us on Twitter @NASA_Johnson and include the ha...

  14. Tracking in high-frame-rate imaging.

    PubMed

    Wu, Shih-Ying; Wang, Shun-Li; Li, Pai-Chi

    2010-01-01

    Speckle tracking has been used for motion estimation in ultrasound imaging. Unlike conventional Doppler techniques, which are angle-dependent, speckle tracking can be utilized to estimate velocity vectors. However, the accuracy of speckle-tracking methods is limited by speckle decorrelation, which is related to the displacement between two consecutive images, and, hence, combining high-frame-rate imaging and speckle tracking could potentially increase the accuracy of motion estimation. However, the lack of transmit focusing may also affect the tracking results and the high computational requirement may be problematic. This study therefore assessed the performance of high-frame-rate speckle tracking and compared it with conventional focusing. The effects of the signal-to-noise ratio (SNR), bulk motion, and velocity gradients were investigated in both experiments and simulations. The results show that high-frame-rate speckle tracking can achieve high accuracy if the SNR is sufficiently high. In addition, its computational complexity is acceptable because smaller search windows can be used due to the displacements between frames generally being smaller during high-frame-rate imaging. Speckle decor-relation resulting from velocity gradients within a sample volume is also not as significant during high-frame-rate imaging. PMID:20690428

  15. Selective advantage for sexual reproduction

    NASA Astrophysics Data System (ADS)

    Tannenbaum, Emmanuel

    2006-06-01

    This paper develops a simplified model for sexual reproduction within the quasispecies formalism. The model assumes a diploid genome consisting of two chromosomes, where the fitness is determined by the number of chromosomes that are identical to a given master sequence. We also assume that there is a cost to sexual reproduction, given by a characteristic time τseek during which haploid cells seek out a mate with which to recombine. If the mating strategy is such that only viable haploids can mate, then when τseek=0 , it is possible to show that sexual reproduction will always out compete asexual reproduction. However, as τseek increases, sexual reproduction only becomes advantageous at progressively higher mutation rates. Once the time cost for sex reaches a critical threshold, the selective advantage for sexual reproduction disappears entirely. The results of this paper suggest that sexual reproduction is not advantageous in small populations per se, but rather in populations with low replication rates. In this regime, the cost for sex is sufficiently low that the selective advantage obtained through recombination leads to the dominance of the strategy. In fact, at a given replication rate and for a fixed environment volume, sexual reproduction is selected for in high populations because of the reduced time spent finding a reproductive partner.

  16. Stress and success: individual differences in the glucocorticoid stress response predict behavior and reproductive success under high predation risk.

    PubMed

    Vitousek, Maren N; Jenkins, Brittany R; Safran, Rebecca J

    2014-11-01

    A fundamental element of how vertebrates respond to stressors is by rapidly elevating circulating glucocorticoid hormones. Individual variation in the magnitude of the glucocorticoid stress response has been linked with reproductive success and survival. But while the adaptive value of this response is believed to stem in part from changes in the expression of hormone-mediated behaviors, it is not clear how the behavior of stronger and weaker glucocorticoid responders differs during reproduction, or during exposure to ecologically relevant stressors. Here we report that in a population of barn swallows (Hirundo rustica erythrogaster) experiencing high rates of nest predation, circulating levels of corticosterone (the primary avian glucocorticoid) during exposure to a standardized stressor predict aspects of subsequent behavior and fitness. Individuals that mounted a stronger corticosterone stress response during the early reproductive period did not differ in clutch size, but fledged fewer offspring. Parents with higher stress-induced corticosterone during the early reproductive period later provisioned their nestlings at lower rates. Additionally, in the presence of a model predator stress-induced corticosterone was positively associated with the latency to return to the nest, but only among birds that were observed to return. Model comparisons revealed that stress-induced hormones were better predictors of the behavioral and fitness effects of exposure to transient, ecologically relevant stressors than baseline corticosterone. These findings are consistent with functional links between individual variation in the hormonal and behavioral response to stressors. If such links occur, then selection on the heritable components of the corticosterone stress response could promote adaptation to novel environments or predation regimes. PMID:25461975

  17. Ensuring Reproduction at High Temperatures: The Heat Stress Response during Anther and Pollen Development

    PubMed Central

    Giorno, Filomena; Wolters-Arts, Mieke; Mariani, Celestina; Rieu, Ivo

    2013-01-01

    Sexual reproduction in flowering plants is very sensitive to environmental stresses, particularly to thermal insults which frequently occur when plants grow in field conditions in the warm season. Although abnormalities in both male and female reproductive organs due to high temperatures have been described in several crops, the failure to set fruits has mainly been attributed to the high sensitivity of developing anthers and pollen grains, particularly at certain developmental stages. A global view of the molecular mechanisms involved in the response to high temperatures in the male reproductive organs will be presented in this review. In addition, transcriptome and proteomic data, currently available, will be discussed in the light of physiological and metabolic changes occurring during anther and pollen development. A deep understanding of the molecular mechanisms involved in the stress response to high temperatures in flowers and, particularly, in the male reproductive organs will be a major step towards development of effective breeding strategies for high and stable production in crop plants. PMID:27137389

  18. Hard times in the city – attractive nest sites but insufficient food supply lead to low reproduction rates in a bird of prey

    PubMed Central

    2014-01-01

    Introduction Urbanization is a global phenomenon that is encroaching on natural habitats and decreasing biodiversity, although it is creating new habitats for some species. The Eurasian kestrel (Falco tinnunculus) is frequently associated with urbanized landscapes but it is unclear what lies behind the high densities of kestrels in the urban environment. Results Occupied nest sites in the city of Vienna, Austria were investigated along a gradient of urbanization (percentage of land covered by buildings or used by traffic). Field surveys determined the abundance of potential prey (birds and rodents) and the results were compared to the birds’ diets. A number of breeding parameters were recorded over the course of three years. The majority of kestrels breed in semi-natural cavities in historic buildings. Nearest neighbour distances (NND) were smallest and reproductive success lowest in the city centre. Abundance of potential prey was not found to relate to the degree of urbanization but there was a significant shift in the birds’ diets from a heavy reliance on rodents in the outskirts of the city to feeding more on small birds in the centre. The use of urban habitats was associated with higher nest failure, partly associated with predation and nest desertion, and with significantly lower hatching rates and smaller fledged broods. Conclusions High breeding densities in urban habitats do not necessarily correlate with high habitat quality. The high density of kestrel nests in the city centre is probably due to the ready availability of breeding cavities. Highly urbanized areas in Vienna are associated with unexpected costs for the city dwelling-raptor, in terms both of prey availability and of reproductive success. The kestrel appears to be exploiting the urban environment but given the poor reproductive performance of urban kestrels it is likely that the species is falling into an ecological trap. PMID:24872836

  19. High Strain Rate Rheology of Polymer Melts

    NASA Astrophysics Data System (ADS)

    Kelly, Adrian; Gough, Tim; Whiteside, Ben; Coates, Phil D.

    2009-07-01

    A modified servo electric injection moulding machine has been used in air-shot mode with capillary dies fitted at the nozzle to examine the rheology of a number of commercial polymers at wall shear strain rates of up to 107 s-1. Shear and extensional flow properties were obtained through the use of long and orifice (close to zero land length) dies of the same diameter. A range of polyethylene, polypropylene and polystyrene melts have been characterized; good agreement was found between the three techniques used in the ranges where strain rates overlapped. Shear viscosity of the polymers studied was found to exhibit a plateau above approximately 1×106 s-1. A relationship between the measured high strain rate rheological behaviour and molecular structure was noted, with polymers containing larger side groups reaching the rate independent plateau at lower strain rates than those with simpler structures.

  20. MITIGATION OF AVIAN REPRODUCTIVE TRACT FUNCTION BY SALMONELLA ENTERITIDIS PRODUCING HIGH-MILECULAR-MASS LIPOPPOLYSACCHARIDE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hens were infected with a wild-type Salmonella enteritidis and its wzz mutant, which lacked the ability to make high-molecular-mass lipopolysaccharide, in six experiments paired by dosage and by route of exposure. Hens underwent involution of the reproductive tract when injected subcutaneously with ...

  1. Effects of feeding high-linoleate safflower seeds on postpartum reproduction in beef cows

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Two experiments were conducted to evaluate reproductive responses to supplemental high-linoleate safflower seeds in postpartum beef cows. In Exp. 1, 18 primiparous, crossbred beef cows (BW 411 ± 24.3 kg) were fed Foxtail millet hay at 1.68% of BW (DM basis) and either a low-fat control (Control: 63...

  2. High pathogenicity avian influenza virus in the reproductive tract of chickens

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Infection with high pathogenicity avian influenza virus (HPAIV) has been associated with a wide range of clinical manifestations in poultry including severe depression in egg production and isolation of HPAIV from eggs laid by infected hens. To evaluate the pathobiology in the reproductive tract of...

  3. Highly pathogenic Chinese porcine reproductive and respiratory syndrome virus strain JXwn06 in US swine

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In 2006, a large-scale outbreak of highly pathogenic atypical porcine reproductive and respiratory syndrome virus (PRRSV) spread throughout the swine population in China. Causative PRRSV isolates were characterized genetically by a unique 30aa deletion in PRRSV nonstructural protein 2 and clinically...

  4. High doses of dietary zinc induce cytokines, chemokines, and apoptosis in reproductive tissues during regression.

    PubMed

    Sundaresan, N R; Anish, D; Sastry, K V H; Saxena, V K; Nagarajan, K; Subramani, J; Leo, M D M; Shit, N; Mohan, J; Saxena, M; Ahmed, K A

    2008-06-01

    In chickens, high levels of dietary zinc cause molting, and the reproductive system undergoes complete remodeling concomitant to feather replacement. In the present study, the expression profiles of cytokines and chemokines were investigated in the ovary and oviduct of control hens and of hens induced to molt by zinc feeding. The zinc-induced feed-intake suppression, the changes in corticosterone levels, the immune cell populations in the reproductive tract, and the apoptosis of reproductive tissues were analyzed. The expression of mRNAs for interleukin-6 (IL-6), interferon-gamma (IFN-gamma), the avian ortholog of mammalian IL-8 (chCXCLi2), and a chicken MIP-1beta-like chemokine (chCCLi2) in the ovary and of mRNAs for IL-1beta, IL-6, IFN-gamma, transforming growth factor-beta2, chCXCLi2, and chCCLi2 in the oviduct were upregulated significantly during zinc-induced molting. A simultaneous feed-intake reduction was observed with higher expression of cytokines and chemokines. The results of the present investigation also suggested that the upregulation of corticosterone was closely associated with the increased expression of cytokines and chemokines. An increase in apoptosis within reproductive tissue during tissue regression was also noted. We had previously observed the upregulation of these cytokines expression in an earlier study (molting by feed withdrawal). However, the pattern and the level of expression were different among these two methods. These findings indicate that cytokines might be a common mediator of tissue regression during molting induced by diverse methods, although the pattern of induction is different. Thus, a high dose of dietary zinc seems to induce reproductive regression via the upregulation of cytokines and chemokines, the suppression of feed intake, and the increase in serum corticosterone, resulting finally in the apoptosis of reproductive tissues. PMID:18351392

  5. Predictive model of rat reproductive toxicity from ToxCast high throughput screening.

    PubMed

    Martin, Matthew T; Knudsen, Thomas B; Reif, David M; Houck, Keith A; Judson, Richard S; Kavlock, Robert J; Dix, David J

    2011-08-01

    The U.S. Environmental Protection Agency's ToxCast research program uses high throughput screening (HTS) for profiling bioactivity and predicting the toxicity of large numbers of chemicals. ToxCast Phase I tested 309 well-characterized chemicals in more than 500 assays for a wide range of molecular targets and cellular responses. Of the 309 environmental chemicals in Phase I, 256 were linked to high-quality rat multigeneration reproductive toxicity studies in the relational Toxicity Reference Database. Reproductive toxicants were defined here as having achieved a reproductive lowest-observed-adverse-effect level of less than 500 mg kg(-1) day(-1). Eight-six chemicals were identified as reproductive toxicants in the rat, and 68 of those had sufficient in vitro bioactivity to model. Each assay was assessed for univariate association with the identified reproductive toxicants. Significantly associated assays were linked to gene sets and used for the subsequent predictive modeling. Using linear discriminant analysis and fivefold cross-validation, a robust and stable predictive model was produced capable of identifying rodent reproductive toxicants with 77% ± 2% and 74% ± 5% (mean ± SEM) training and test cross-validation balanced accuracies, respectively. With a 21-chemical external validation set, the model was 76% accurate, further indicating the model's potential for prioritizing the many thousands of environmental chemicals with little to no hazard information. The biological features of the model include steroidal and nonsteroidal nuclear receptors, cytochrome P450 enzyme inhibition, G protein-coupled receptors, and cell signaling pathway readouts-mechanistic information suggesting additional targeted, integrated testing strategies and potential applications of in vitro HTS to risk assessment. PMID:21565999

  6. A high-strain-rate superplastic ceramic.

    PubMed

    Kim, B N; Hiraga, K; Morita, K; Sakka, Y

    2001-09-20

    High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great technological interest for the shape-forming of engineering materials. High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates of the order of 10-5 to 10-4 s-1 for most oxides and nitrides with the presence of intergranular cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminate spinel and alpha-alumina phases exhibits superplasticity at strain rates up to 1 s-1. The composite also exhibits a large tensile elongation, exceeding 1,050 per cent for a strain rate of 0.4 s-1. The tensile flow behaviour and deformed microstructure of the material indicate that superplasticity is due to a combination of limited grain growth in the constitutive phases and the intervention of dislocation-induced plasticity in the zirconium oxide phase. We suggest that the present results hold promise for the application of shape-forming technologies to ceramic materials. PMID:11565026

  7. High Bit Rate Experiments Over ACTS

    NASA Technical Reports Server (NTRS)

    Bergman, Larry A.; Gary, J. Patrick; Edelsen, Burt; Helm, Neil; Cohen, Judith; Shopbell, Patrick; Mechoso, C. Roberto; Chung-Chun; Farrara, M.; Spahr, Joseph

    1996-01-01

    This paper describes two high data rate experiments chat are being developed for the gigabit NASA Advanced Communications Technology Satellite (ACTS). The first is a telescience experiment that remotely acquires image data at the Keck telescope from the Caltech campus. The second is a distributed global climate application that is run between two supercomputer centers interconnected by ACTS. The implementation approach for each is described along with the expected results. Also. the ACTS high data rate (HDR) ground station is also described in detail.

  8. Late snowmelt delays plant development and results in lower reproductive success in the High Arctic.

    PubMed

    Cooper, Elisabeth J; Dullinger, Stefan; Semenchuk, Philipp

    2011-01-01

    In tundra areas where the growing season is short, any delay in the start of summer may have a considerable effect on plant development, growth and reproductive success. Climate models suggest long-term changes in winter precipitation in the Arctic, which may lead to deeper snow cover and a resultant delay in date of snow melt. In this paper, we investigated the role of snow depth and melt out date on the phenological development and reproductive success of vascular plants in Adventdalen, Svalbard (78° 10'N, 16° 06'E). Effects of natural variations in snow accumulation were demonstrated using two vegetation types (snow depth: meadow 21 cm, heath 32 cm), and fences were used to experimentally increase snow depth by over 1m. Phenological delay was greatest directly after snowmelt in the earlier phenological phases, and had the largest effect on the early development of those species which normally green-up early (i.e. Dryas, Papaver, Salix, Saxifraga). Compressed growing seasons and length of the reproductive period led to a reduced reproductive success in some of the study species. There were fewer flowers, fewer plots with dispersing seeds, and lower germination rates. This can have consequences for plant establishment and community composition in the long-term. PMID:21421357

  9. The high producing dairy cow and its reproductive performance

    PubMed Central

    Dobson, H; Smith, RF; Royal, MD; Knight, CH; Sheldon, IM

    2009-01-01

    Contents: Intensive genetic selection has resulted in modern dairy cow with very high milk yields but reduced fertility, due mainly to an increase in postpartum clinical problems, poor expression of oestrus, defective oocytes/embryos and uterine infections. It is a challenge to get enough food into these cows to meet the high demands of peak milk yields in early lactation and the animals require considerable veterinary attention in the early period after calving. Both genetic and management changes to increase the persistency of lactations would reduce the number and intensity of clinical risk periods throughout a cow's life without compromising milk output. PMID:17688598

  10. High Rate for Type IC Supernovae

    SciTech Connect

    Muller, R.A.; Marvin-Newberg, H.J.; Pennypacker, Carl R.; Perlmutter, S.; Sasseen, T.P.; Smith, C.K.

    1991-09-01

    Using an automated telescope we have detected 20 supernovae in carefully documented observations of nearby galaxies. The supernova rates for late spiral (Sbc, Sc, Scd, and Sd) galaxies, normalized to a blue luminosity of 10{sup 10} L{sub Bsun}, are 0.4 h{sup 2}, 1.6 h{sup 2}, and 1.1 h{sup 2} per 100 years for SNe type la, Ic, and II. The rate for type Ic supernovae is significantly higher than found in previous surveys. The rates are not corrected for detection inefficiencies, and do not take into account the indications that the Ic supernovae are fainter on the average than the previous estimates; therefore the true rates are probably higher. The rates are not strongly dependent on the galaxy inclination, in contradiction to previous compilations. If the Milky Way is a late spiral, then the rate of Galactic supernovae is greater than 1 per 30 {+-} 7 years, assuming h = 0.75. This high rate has encouraging consequences for future neutrino and gravitational wave observatories.

  11. Baltimore District Tackles High Suspension Rates

    ERIC Educational Resources Information Center

    Maxwell, Lesli A.

    2007-01-01

    This article reports on how the Baltimore District tackles its high suspension rates. Driven by an increasing belief that zero-tolerance disciplinary policies are ineffective, more educators are embracing strategies that do not exclude misbehaving students from school for offenses such as insubordination, disrespect, cutting class, tardiness, and…

  12. Understanding High School Graduation Rates in Illinois

    ERIC Educational Resources Information Center

    Alliance for Excellent Education, 2009

    2009-01-01

    Graduation rates are a fundamental indicator of whether or not the nation's public school system is doing what it is intended to do: enroll, engage, and educate youth to be productive members of society. Since almost 90 percent of the fastest-growing and highest-paying jobs require some postsecondary education, having a high school diploma and the…

  13. Understanding High School Graduation Rates in Delaware

    ERIC Educational Resources Information Center

    Alliance for Excellent Education, 2009

    2009-01-01

    Graduation rates are a fundamental indicator of whether or not the nation's public school system is doing what it is intended to do: enroll, engage, and educate youth to be productive members of society. Since almost 90 percent of the fastest-growing and highest-paying jobs require some postsecondary education, having a high school diploma and the…

  14. A HIGH-THROUGHPUT METHOD FOR ASSESSING CHEMICAL TOXICITY USING A CAENORHABDITIS ELEGANS REPRODUCTION ASSAY

    PubMed Central

    Boyd, Windy A.; McBride, Sandra J.; Rice, Julie R.; Snyder, Daniel W.; Freedman, Jonathan H.

    2010-01-01

    The National Research Council has outlined the need for non-mammalian toxicological models to test the potential health effects of a large number of chemicals while also reducing the use of traditional animal models. The nematode Caenorhabditis elegans is an attractive alternative model because of its well-characterized and evolutionarily-conserved biology, low cost, and ability to be used in high-throughput screening. A high-throughput method is described for quantifying the reproductive capacity of C. elegans exposed to chemicals for 48 h from the last larval stage (L4) to adulthood using a COPAS Biosort. Initially, the effects of exposure conditions that could influence reproduction were defined. Concentrations of DMSO vehicle ≤ 1% did not affect reproduction. Previous studies indicated that C. elegans may be influenced by exposure to low pH conditions. At pHs greater than 4.5, C. elegans reproduction was not affected, however below this pH there was a significant decrease in the number of offspring. Cadmium chloride was chosen as a model toxicant to verify that automated measurements were comparable to those of traditional observational studies. EC50 values for cadmium for automated measurements (176-192 μM) were comparable to those previously reported for a 72-h exposure using manual counting (151 μM). The toxicity of seven test toxicants on C. elegans reproduction was highly correlative with rodent lethality suggesting that this assay may be useful in predicting the potential toxicity of chemicals in other organisms. PMID:20206647

  15. A high-throughput method for assessing chemical toxicity using a Caenorhabditis elegans reproduction assay

    SciTech Connect

    Boyd, Windy A.; McBride, Sandra J.; Rice, Julie R.; Snyder, Daniel W.; Freedman, Jonathan H.

    2010-06-01

    The National Research Council has outlined the need for non-mammalian toxicological models to test the potential health effects of a large number of chemicals while also reducing the use of traditional animal models. The nematode Caenorhabditis elegans is an attractive alternative model because of its well-characterized and evolutionarily conserved biology, low cost, and ability to be used in high-throughput screening. A high-throughput method is described for quantifying the reproductive capacity of C. elegans exposed to chemicals for 48 h from the last larval stage (L4) to adulthood using a COPAS Biosort. Initially, the effects of exposure conditions that could influence reproduction were defined. Concentrations of DMSO vehicle {<=} 1% did not affect reproduction. Previous studies indicated that C. elegans may be influenced by exposure to low pH conditions. At pHs greater than 4.5, C. elegans reproduction was not affected; however below this pH there was a significant decrease in the number of offspring. Cadmium chloride was chosen as a model toxicant to verify that automated measurements were comparable to those of traditional observational studies. EC{sub 50} values for cadmium for automated measurements (176-192 {mu}M) were comparable to those previously reported for a 72-h exposure using manual counting (151 {mu}M). The toxicity of seven test toxicants on C. elegans reproduction was highly correlative with rodent lethality suggesting that this assay may be useful in predicting the potential toxicity of chemicals in other organisms.

  16. Does the silver moss Bryum argenteum exhibit sex-specific patterns in vegetative growth rate, asexual fitness or prezygotic reproductive investment?

    PubMed Central

    Horsley, Kimberly; Stark, Lloyd R.; McLetchie, D. Nicholas

    2011-01-01

    Background and Aims Expected life history trade-offs associated with sex differences in reproductive investment are often undetected in seed plants, with the difficulty arising from logistical issues of conducting controlled experiments. By controlling genotype, age and resource status of individuals, a bryophyte was assessed for sex-specific and location-specific patterns of vegetative, asexual and sexual growth/reproduction across a regional scale. Methods Twelve genotypes (six male, six female) of the dioecious bryophyte Bryum argenteum were subcultured to remove environmental effects, regenerated asexually to replicate each genotype 16 times, and grown over a period of 92 d. Plants were assessed for growth rates, asexual and sexual reproductive traits, and allocation to above- and below-ground regenerative biomass. Key Results The degree of sexual versus asexual reproductive investment appears to be under genetic control, with three distinct ecotypes found in this study. Protonemal growth rate was positively correlated with asexual reproduction and sexual reproduction, whereas asexual reproduction was negatively correlated (appeared to trade-off) with vegetative growth (shoot production). No sex-specific trade-offs were detected. Female sex-expressing shoots were longer than males, but the sexes did not differ in growth traits, asexual traits, sexual induction times, or above- and below-ground biomass. Males, however, had much higher rates of inflorescence production than females, which translated into a significantly higher (24x) prezygotic investment for males relative to females. Conclusions Evidence for three distinct ecotypes is presented for a bryophyte based on regeneration traits. Prior to zygote production, the sexes of this bryophyte did not differ in vegetative growth traits but significantly differed in reproductive investment, with the latter differences potentially implicated in the strongly biased female sex ratio. The disparity between males and

  17. The effect of intrauterine infusion of dextrose on clinical endometritis cure rate and reproductive performance of dairy cows.

    PubMed

    Machado, V S; Oikonomou, G; Ganda, E K; Stephens, L; Milhomem, M; Freitas, G L; Zinicola, M; Pearson, J; Wieland, M; Guard, C; Gilbert, R O; Bicalho, R C

    2015-06-01

    The main objective of this study was to evaluate the intrauterine administration use of 200 mL of 50% dextrose solution as a treatment against clinical endometritis (CE); CE cure rate and reproductive performance were evaluated. Additionally, the association of several relevant risk factors, such as retained placenta (RP), metritis, CE, anovulation, hyperketonemia, and body condition score with reproductive performance, early embryonic mortality, and CE were evaluated. A total of 1,313 Holstein cows housed on 4 commercial dairy farms were enrolled in the study. At 7±3 DIM cows were examined for metritis and had blood collected to determine serum β-hydroxybutyrate concentration. To determine if cows had ovulated at least once before 44±3 DIM, the presence of a corpus luteum was evaluated by ovarian ultrasonography at 30±3 DIM and at 44±3 DIM. At 30±3 DIM, CE was diagnosed using the Metricheck device (SimcroTech, Hamilton, New Zealand); cows with purulent or mucopurulent vaginal discharge were diagnosed as having CE. Cows diagnosed with CE (n=175) were randomly allocated into 2 treatment groups: treatment (intrauterine infusion of 200 mL of 50% dextrose) or control (no infusion). Clinical endometritis cows were re-evaluated as described above at 44±3 DIM, and cows that were free of purulent or mucopurulent vaginal discharge were considered cured. Intrauterine infusion of dextrose tended to have a detrimental effect on CE cure rate, and treatment did not have an effect on first-service conception rate and early embryonic mortality. A multivariable Cox's proportional hazard model was performed to evaluate the effect of several variables on reproductive performance; the variables RP, CE, parity, anovulation, and the interaction term between parity and anovulation were associated with hazard of pregnancy. Cows that did not have RP or CE were more likely to conceive than cows that were diagnosed with RP or CE. Cows that had RP were at 3.36 times higher odds of

  18. High rate vacuum deposited silicon layers

    NASA Astrophysics Data System (ADS)

    Kipperman, A. H. M.; van Zolingen, R. J. C.

    1982-08-01

    Silicon layers were deposited in vacuum at high rates (up to 50 microns/min) on aluminum-, silicon oxide-, and silicon nitride-coated stainless steel, pyrex, and silicon substrates. The morphological, crystallographic, and electrical properties of the layers were studied in as-grown and annealed conditions. Layers as-grown on aluminum-coated substrates had unsatisfactory electrical properties and too high an aluminum concentration to be acceptable for solar cells. Thermal annealing of layers on SiO2- and on Si3N4-coated substrates markedly improved their crystallographic and electrical properties. In all cases, silicon layers deposited at about 550 C showed a columnar structure which, after prolonged etching, was found to be composed of fibrils of about 0.3 microns in diameter extending over the entire thickness of the layer. It is suggested that further tests should be carried out at a substrate temperature of about 800 C maintaining the high deposition rates.

  19. High strain rate behaviour of polypropylene microfoams

    NASA Astrophysics Data System (ADS)

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  20. Reproductive and behavioral abnormalities in tree swallows with high levels of PCB contamination

    SciTech Connect

    McCarty, J.; Secord, A.; Tillitt, D.

    1995-12-31

    Tree Swallows (Tachycineta bicolor) breeding along the Hudson River forage extensively on PCB contaminated insects that emerge from the river. The authors studied the reproductive ecology and behavior of tree swallows breeding at several sites along the Hudson River. These sites vary in the severity of PCB contamination. PCB levels in both eggs and chicks were found to be among the highest ever reported in this species, with concentrations comparable to those found in aquatic organisms in the Hudson River. In 1994 reproductive success at PCB contaminated sites was significantly impaired, relative to other sites in New York. Reduced reproductive success was largely attributed to high levels of nest abandonment during incubation and reduced hatchability of eggs. Growth and development of nestlings was not significantly impaired. Abnormal nest building behavior was also noted in 1994, and this was studied in detail in 1995. Nests from contaminated areas are significantly smaller than those at a nearby reference site and at other sites in New York. The authors suggest that the reduced reproductive outputs at these sites are, in large part, a result of effects on the behavior of incubating females. The population-level implications of these patterns are unknown.

  1. Reproductive Science for High School Students: A Shared Curriculum Model to Enhance Student Success.

    PubMed

    Castle, Megan; Cleveland, Charlotte; Gordon, Diana; Jones, Lynda; Zelinski, Mary; Winter, Patricia; Chang, Jeffrey; Senegar-Mitchell, Ericka; Coutifaris, Christos; Shuda, Jamie; Mainigi, Monica; Bartolomei, Marisa; Woodruff, Teresa K

    2016-07-01

    The lack of a national reproductive biology curriculum leads to critical knowledge gaps in today's high school students' comprehensive understanding of human biology. The Oncofertility Consortium developed curricula that address the basic and clinical aspects of reproductive biology. Launching this academy and creating easy-to-disseminate learning modules allowed other universities to implement similar programs across the country. The expansion of this informal, extracurricular academy on reproductive health from Northwestern University to the University of California, San Diego, Oregon Health & Science University, and the University of Pennsylvania magnifies the scope of scientific learning to students who might not otherwise be exposed to this important information. To assess the experience gained from this curriculum, we polled alumni from the four centers. Data were collected anonymously from de-identified users who elected to self-report on their experiences in their respective reproductive science academy. The alumni survey asked participants to report on their current academic standing, past experiences in the academy, and future academic and career goals. The results of this national survey suggest the national oncofertility academies had a lasting impact on participants and may have contributed to student persistence in scientific learning. PMID:27335072

  2. Highly stable high-rate discriminator for nuclear counting

    NASA Technical Reports Server (NTRS)

    English, J. J.; Howard, R. H.; Rudnick, S. J.

    1969-01-01

    Pulse amplitude discriminator is specially designed for nuclear counting applications. At very high rates, the threshold is stable. The output-pulse width and the dead time change negligibly. The unit incorporates a provision for automatic dead-time correction.

  3. High temperature electrochemical corrosion rate probes

    SciTech Connect

    Bullard, Sophie J.; Covino, Bernard S., Jr.; Holcomb, Gordon R.; Ziomek-Moroz, M.

    2005-09-01

    Corrosion occurs in the high temperature sections of energy production plants due to a number of factors: ash deposition, coal composition, thermal gradients, and low NOx conditions, among others. Electrochemical corrosion rate (ECR) probes have been shown to operate in high temperature gaseous environments that are similar to those found in fossil fuel combustors. ECR probes are rarely used in energy production plants at the present time, but if they were more fully understood, corrosion could become a process variable at the control of plant operators. Research is being conducted to understand the nature of these probes. Factors being considered are values selected for the Stern-Geary constant, the effect of internal corrosion, and the presence of conductive corrosion scales and ash deposits. The nature of ECR probes will be explored in a number of different atmospheres and with different electrolytes (ash and corrosion product). Corrosion rates measured using an electrochemical multi-technique capabilities instrument will be compared to those measured using the linear polarization resistance (LPR) technique. In future experiments, electrochemical corrosion rates will be compared to penetration corrosion rates determined using optical profilometry measurements.

  4. High strain rate damage of Carrara marble

    NASA Astrophysics Data System (ADS)

    Doan, Mai-Linh; Billi, Andrea

    2011-10-01

    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  5. High Rate Data Delivery Thrust Area

    NASA Technical Reports Server (NTRS)

    Bhasin, Kul

    2000-01-01

    In this paper, a brief description of the high rate data delivery (HRDD) thrust area, its focus and current technical activities being carried out by NASA centers including JPL, academia and industry under this program is provided. The processes and methods being used to achieve active participation in this program are presented. The developments in space communication technologies, which will shape NASA enterprise missions in the 21 st. century, are highlighted.

  6. HIGH ENERGY RATE EXTRUSION OF URANIUM

    DOEpatents

    Lewis, L.

    1963-07-23

    A method of extruding uranium at a high energy rate is described. Conditions during the extrusion are such that the temperature of the metal during extrusion reaches a point above the normal alpha to beta transition, but the metal nevertheless remains in the alpha phase in accordance with the Clausius- Clapeyron equation. Upon exiting from the die, the metal automatically enters the beta phase, after which the metal is permitted to cool. (AEC)

  7. Reproduction, aging and mortality rate in social subterranean mole voles (Ellobius talpinus Pall.).

    PubMed

    Novikov, E; Kondratyuk, E; Petrovski, D; Titova, T; Zadubrovskaya, I; Zadubrovskiy, P; Moshkin, M

    2015-12-01

    Eusocial subterranean rodents of the Bathyergidae family have enormous longevity. The long lifespan of these species is associated with negligible senescence, that is, an absence of the signs of age-related deterioration in physical condition. The question arises as to whether these features are unique to eusocial Bathyergids or typical of other social subterranean rodents as well. In the present study, we analysed data from observations of a social subterranean Microtinae rodent, the northern mole vole (Ellobius talpinus Pall.), which, like mole-rats, has reproductive skew. Among the individuals captured in the wild and maintained in captivity, females that reproduced lived significantly longer than non-breeding females. We did not find any changes in muscle strength with age in any of the demographic groups studied. Faecal glucocorticoid concentrations before death were significantly higher in non-breeding females than in breeding females and males. Increased adrenocortical activity may be one mechanism responsible for the decreased lifespan of non-reproducing individuals of social subterranean rodents. We conclude that the patterns of aging, although different in some respects, are generally common for social subterranean rodents of different taxonomic groups. PMID:26208910

  8. Reserve, flowing electrolyte, high rate lithium battery

    NASA Astrophysics Data System (ADS)

    Puskar, M.; Harris, P.

    Flowing electrolyte Li/SOCl2 tests in single cell and multicell bipolar fixtures have been conducted, and measurements are presented for electrolyte flow rates, inlet and outlet temperatures, fixture temperatures at several points, and the pressure drop across the fixture. Reserve lithium batteries with flowing thionyl-chloride electrolytes are found to be capable of very high energy densities with usable voltages and capacities at current densities as high as 500 mA/sq cm. At this current density, a battery stack 10 inches in diameter is shown to produce over 60 kW of power while maintaining a safe operating temperature.

  9. The adverse effects of high fat induced obesity on female reproductive cycle and hormones

    NASA Astrophysics Data System (ADS)

    Donthireddy, Laxminarasimha Reddy

    The prevalence of obesity, an established risk and progression factor for abnormal reproductive cycle and tissue damage in female mice. It leads to earlier puberty, menarche in young females and infertility. There are extensive range of consequences of obesity which includes type-2 diabetes, cardiovascular disease and insulin resistance. Obesity is the interaction between dietary intake, genes, life style and environment. The interplay of hormones estrogen, insulin, and leptin is well known on energy homeostasis and reproduction. The aim of this study is to determine the effect of high fat induced obesity on reproductive cycles and its hormonal abnormalities on mice model. Two week, 3 month and 8 month long normal (WT) and very high fat diet (VHFD) diet course is followed. When mice are fed with very high fat diet, there is a drastic increase in weight within the first week later. There was a significant (p<0.001) increase in leptin levels in 6 month VHFD treated animals. 2 week, 3 month and 6 month time interval pap smear test results showed number of cells, length of estrous cycle and phases of the estrous cycle changes with VHFD mice(n=30) compared to normal diet mice(n=10). These results also indicate that the changes in the reproductive cycles in VHFD treated female mice could be due to the changes in hormones. Histo-pathological analyses of kidney, ovary, liver, pancreas, heart and lungs showed remarkable changes in some tissue on exposure to very high fat. Highly deposited fat packets observed surrounding the hepatocytes and nerve cells.

  10. Optimization of coplanar high rate supercapacitors

    NASA Astrophysics Data System (ADS)

    Sun, Leimeng; Wang, Xinghui; Liu, Wenwen; Zhang, Kang; Zou, Jianping; Zhang, Qing

    2016-05-01

    In this work, we describe two efficient methods to enhance the electrochemical performance of high-rate coplanar micro-supercapacitors (MSCs). Through introducing MnO2 nanosheets on vertical-aligned carbon nanotube (VACNT) array, the areal capacitance and volumetric energy density exhibit tremendous improvements which have been increased from 0.011 mF cm-2 to 0.017 mWh cm-3 to 0.479 mF cm-2 and 0.426 mWh cm-3 respectively at an ultrahigh scan rate of 50000 mV s-1. Subsequently, by fabricating an asymmetric MSC, the energy density could be increased to 0.167 mWh cm-3 as well. Moreover, as a result of applying MnO2/VACNT as the positive electrode and VACNT as the negative electrode, the cell operating voltage in aqueous electrolyte could be increased to as high as 2.0 V. Our advanced planar MSCs could operate well at different high scan rates and offer a promising integration potential with other in-plane devices on the same substrate.

  11. Optimization of coplanar high rate supercapacitors

    NASA Astrophysics Data System (ADS)

    Sun, Leimeng; Wang, Xinghui; Liu, Wenwen; Zhang, Kang; Zou, Jianping; Zhang, Qing

    2016-05-01

    In this work, we describe two efficient methods to enhance the electrochemical performance of high-rate coplanar micro-supercapacitors (MSCs). Through introducing MnO2 nanosheets on vertical-aligned carbon nanotube (VACNT) array, the areal capacitance and volumetric energy density exhibit tremendous improvements which have been increased from 0.011 mF cm-2 to 0.017 mWh cm-3 to 0.479 mF cm-2 and 0.426 mWh cm-3 respectively at an ultrahigh scan rate of 50000 mV s-1. Subsequently, by fabricating an asymmetric MSC, the energy density could be increased to 0.167 mWh cm-3 as well. Moreover, as a result of applying MnO2/VACNT as the positive electrode and VACNT as the negative electrode, the cell operating voltage in aqueous electrolyte could be increased to as high as 2.0 V. Our advanced planar MSCs could operate well at different high scan rates and offer a promising integration potential with other in-plane devices on the same substrate.

  12. Civilian residential fire fatality rates: Six high-rate states versus six low-rate states

    NASA Astrophysics Data System (ADS)

    Hall, J. R., Jr.; Helzer, S. G.

    1983-08-01

    Results of an analysis of 1,600 fire fatalities occurring in six states with high fire-death rates and six states with low fire-death rates are presented. Reasons for the differences in rates are explored, with special attention to victim age, sex, race, and condition at time of ignition. Fire cause patterns are touched on only lightly but are addressed more extensively in the companion piece to this report, "Rural and Non-Rural Civilian Residential Fire Fatalities in Twelve States', NBSIR 82-2519.

  13. High reproductive synchrony of Acropora (Anthozoa: Scleractinia) in the Gulf of Aqaba, Red Sea

    PubMed Central

    Bouwmeester, Jessica; Berumen, Michael L.

    2015-01-01

    Coral spawning in the northern Gulf of Aqaba has been reported to be asynchronous, making it almost unique when compared to other regions in the world. Here, we document the reproductive condition of Acropora corals in early June 2014 in Dahab, in the Gulf of Aqaba, 125 km south of previous studies conducted in Eilat, Israel. Seventy-eight percent of Acropora colonies from 14 species had mature eggs, indicating that most colonies will spawn on or around the June full moon, with a very high probability of multi-species synchronous spawning. Given the proximity to Eilat, we predict that a comparable sampling protocol would detect similar levels of reproductive synchrony throughout the Gulf of Aqaba consistent with the hypothesis that high levels of spawning synchrony are a feature of all speciose coral assemblages. PMID:25653848

  14. A visibility matching tone reproduction operator for high dynamic range scenes

    SciTech Connect

    Larson, G.W.; Rushmeier, H.; Piatko, C.

    1997-01-15

    The authors present a tone reproduction operator that preserves visibility in high dynamic range scenes. The method introduces a new histogram adjustment technique, based on the population of local adaptation luminances in a scene. To match subjective viewing experience, the method incorporates models for human contrast sensitivity, glare, spatial acuity and color sensitivity. They compare the results to previous work and present examples the techniques applied to lighting simulation and electronic photography.

  15. High rate pulse processing algorithms for microcalorimeters

    SciTech Connect

    Rabin, Michael; Hoover, Andrew S; Bacrania, Mnesh K; Tan, Hui; Breus, Dimitry; Henning, Wolfgang; Sabourov, Konstantin; Collins, Jeff; Warburton, William K; Dorise, Bertrand; Ullom, Joel N

    2009-01-01

    It has been demonstrated that microcalorimeter spectrometers based on superconducting transition-edge-sensor can readily achieve sub-100 eV energy resolution near 100 keV. However, the active volume of a single microcalorimeter has to be small to maintain good energy resolution, and pulse decay times are normally in the order of milliseconds due to slow thermal relaxation. Consequently, spectrometers are typically built with an array of microcalorimeters to increase detection efficiency and count rate. Large arrays, however, require as much pulse processing as possible to be performed at the front end of the readout electronics to avoid transferring large amounts of waveform data to a host computer for processing. In this paper, they present digital filtering algorithms for processing microcalorimeter pulses in real time at high count rates. The goal for these algorithms, which are being implemented in the readout electronics that they are also currently developing, is to achieve sufficiently good energy resolution for most applications while being (a) simple enough to be implemented in the readout electronics and (b) capable of processing overlapping pulses and thus achieving much higher output count rates than the rates that existing algorithms are currently achieving. Details of these algorithms are presented, and their performance was compared to that of the 'optimal filter' that is the dominant pulse processing algorithm in the cryogenic-detector community.

  16. High Strain Rate Behavior of Polyurea Compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant; Milby, Christopher

    2011-06-01

    Polyurea has been gaining importance in recent years due to its impact resistance properties. The actual compositions of this viscoelastic material must be tailored for specific use. It is therefore imperative to study the effect of variations in composition on the properties of the material. High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with titanium bars. The polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. The materials have been tested up to strain rates of 6000/s. Results from these tests have shown interesting trends on the high rate behavior. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Refinement in experimental methods and comparison of results using aluminum Split Hopkinson Bar is presented.

  17. High strain rate behavior of polyurea compositions

    NASA Astrophysics Data System (ADS)

    Joshi, Vasant S.; Milby, Christopher

    2012-03-01

    High-strain-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to strain rates of over 6000/s. High strain rate results from these tests have shown varying trends as a function of increasing strain. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower strain. On the other hand, the blend of 250/1000 show higher load bearing capability but lower strain hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of strain hardening characteristics as the material is compressed to 50% strain, compared to 1000 molecular weight amine based material.

  18. High strain-rate magnetoelasticity in Galfenol

    NASA Astrophysics Data System (ADS)

    Domann, J. P.; Loeffler, C. M.; Martin, B. E.; Carman, G. P.

    2015-09-01

    This paper presents the experimental measurements of a highly magnetoelastic material (Galfenol) under impact loading. A Split-Hopkinson Pressure Bar was used to generate compressive stress up to 275 MPa at strain rates of either 20/s or 33/s while measuring the stress-strain response and change in magnetic flux density due to magnetoelastic coupling. The average Young's modulus (44.85 GPa) was invariant to strain rate, with instantaneous stiffness ranging from 25 to 55 GPa. A lumped parameters model simulated the measured pickup coil voltages in response to an applied stress pulse. Fitting the model to the experimental data provided the average piezomagnetic coefficient and relative permeability as functions of field strength. The model suggests magnetoelastic coupling is primarily insensitive to strain rates as high as 33/s. Additionally, the lumped parameters model was used to investigate magnetoelastic transducers as potential pulsed power sources. Results show that Galfenol can generate large quantities of instantaneous power (80 MW/m3 ), comparable to explosively driven ferromagnetic pulse generators (500 MW/m3 ). However, this process is much more efficient and can be cyclically carried out in the linear elastic range of the material, in stark contrast with explosively driven pulsed power generators.

  19. High strain rate deformation of layered nanocomposites.

    PubMed

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A; Thomas, Edwin L

    2012-01-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers. PMID:23132014

  20. High strain rate deformation of layered nanocomposites

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  1. High frame-rate digital radiographic videography

    SciTech Connect

    King, N.S.P.; Cverna, F.H.; Albright, K.L.; Jaramillo, S.A.; Yates, G.J.; McDonald, T.E.; Flynn, M.J.; Tashman, S.

    1994-09-01

    High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100-microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

  2. High-frame-rate digital radiographic videography

    NASA Astrophysics Data System (ADS)

    King, Nicholas S. P.; Cverna, Frank H.; Albright, Kevin L.; Jaramillo, Steven A.; Yates, George J.; McDonald, Thomas E.; Flynn, Michael J.; Tashman, Scott

    1994-10-01

    High speed x-ray imaging can be an important tool for observing internal processes in a wide range of applications. In this paper we describe preliminary implementation of a system having the eventual goal of observing the internal dynamics of bone and joint reactions during loading. Two Los Alamos National Laboratory (LANL) gated and image intensified camera systems were used to record images from an x-ray image convertor tube to demonstrate the potential of high frame-rate digital radiographic videography in the analysis of bone and joint dynamics of the human body. Preliminary experiments were done at LANL to test the systems. Initial high frame-rate imaging (from 500 to 1000 frames/s) of a swinging pendulum mounted to the face of an X-ray image convertor tube demonstrated high contrast response and baseline sensitivity. The systems were then evaluated at the Motion Analysis Laboratory of Henry Ford Health Systems Bone and Joint Center. Imaging of a 9 inch acrylic disk with embedded lead markers rotating at approximately 1000 RPM, demonstrated the system response to a high velocity/high contrast target. By gating the P-20 phosphor image from the X-ray image convertor with a second image intensifier (II) and using a 100 microsecond wide optical gate through the second II, enough prompt light decay from the x-ray image convertor phosphor had taken place to achieve reduction of most of the motion blurring. Measurement of the marker velocity was made by using video frames acquired at 500 frames/s. The data obtained from both experiments successfully demonstrated the feasibility of the technique. Several key areas for improvement are discussed along with salient test results and experiment details.

  3. Fuel droplet burning rates at high pressures.

    NASA Technical Reports Server (NTRS)

    Canada, G. S.; Faeth, G. M.

    1973-01-01

    Combustion of methanol, ethanol, propanol-1, n-pentane, n-heptane, and n-decane was observed in air under natural convection conditions, at pressures up to 100 atm. The droplets were simulated by porous spheres, with diameters in the range from 0.63 to 1.90 cm. The pressure levels of the tests were high enough so that near-critical combustion was observed for methanol and ethanol. Due to the high pressures, the phase-equilibrium models of the analysis included both the conventional low-pressure approach as well as high-pressure versions, allowing for real gas effects and the solubility of combustion-product gases in the liquid phase. The burning-rate predictions of the various theories were similar, and in fair agreement with the data. The high-pressure theory gave the best prediction for the liquid-surface temperatures of ethanol and propanol-1 at high pressure. The experiments indicated the approach of critical burning conditions for methanol and ethanol at pressures on the order of 80 to 100 atm, which was in good agreement with the predictions of both the low- and high-pressure analysis.

  4. Microalgal separation from high-rate ponds

    SciTech Connect

    Nurdogan, Y.

    1988-01-01

    High rate ponding (HRP) processes are playing an increasing role in the treatment of organic wastewaters in sunbelt communities. Photosynthetic oxygenation by algae has proved to cost only one-seventh as much as mechanical aeration for activated sludge systems. During this study, an advanced HRP, which produces an effluent equivalent to tertiary treatment has been studied. It emphasizes not only waste oxidation but also algal separation and nutrient removal. This new system is herein called advanced tertiary high rate ponding (ATHRP). Phosphorus removal in HRP systems is normally low because algal uptake of phosphorus is about one percent of their 200-300 mg/L dry weights. Precipitation of calcium phosphates by autofluocculation also occurs in HRP at high pH levels, but it is generally not complete due to insufficient calcium concentration in the pond. In the case of Richmond where the studies were conducted, the sewage is very low in calcium. Therefore, enhancement of natural autoflocculation was studied by adding small amounts of lime to the pond. Through this simple procedure phosphorus and nitrogen removals were virtually complete justifying the terminology ATHRP.

  5. The average culling rate of Dutch dairy herds over the years 2007 to 2010 and its association with herd reproduction, performance and health.

    PubMed

    Nor, Norhariani Mohd; Steeneveld, Wilma; Hogeveen, Henk

    2014-02-01

    Optimising the number of replacement heifers needed will have positive economic and environmental consequences on herds that rear their own young stock. The number of heifers needed to be kept is closely related with the number of culled dairy cows in the herd. This study therefore looked at the variation that exists in culling rate and herd level factors associated with it. A dataset from 1903 dairy herds available included information at animal level (dates of culling, slaughter/death) and herd level (characteristics of reproduction, performance, health) over the years 2007 to 2010. The average culling rate for slaughter/death was used and was defined for each year as percentage of the herd size that died within 30 d after they were culled. The analysis of the association between average culling rate for slaughter/death and the characteristics of the herd was performed using a mixed model. The results showed that the average culling rate for slaughter/death was 25·4% and varied between 23% (2007) and 28% (2010). More than 70% of the herds have an average culling rate for slaughter/death of less than 30%, showing that there is room for lowering the average culling rate for slaughter/death. A higher average culling rate for slaughter/death is associated with a longer average calving interval, a higher average 305-d protein production, a higher average somatic cell count (SCC), a higher percentage of new high SCC, a more than 5% decrease in herd size, and herds that bought more than 1% of animals per year. A lower average culling rate for slaughter/death is associated with a longer average age, herds that bought less than 1% of animals per year and a more than 5% increase in herd size. In conclusion, the average culling rate for slaughter/death is associated with fertility, udder health and openness of the herd. PMID:24107585

  6. High Rate Pulse Processing Algorithms for Microcalorimeters

    NASA Astrophysics Data System (ADS)

    Tan, Hui; Breus, Dimitry; Hennig, Wolfgang; Sabourov, Konstantin; Collins, Jeffrey W.; Warburton, William K.; Bertrand Doriese, W.; Ullom, Joel N.; Bacrania, Minesh K.; Hoover, Andrew S.; Rabin, Michael W.

    2009-12-01

    It has been demonstrated that microcalorimeter spectrometers based on superconducting transition-edge-sensors can readily achieve sub-100 eV energy resolution near 100 keV. However, the active volume of a single microcalorimeter has to be small in order to maintain good energy resolution, and pulse decay times are normally on the order of milliseconds due to slow thermal relaxation. Therefore, spectrometers are typically built with an array of microcalorimeters to increase detection efficiency and count rate. For large arrays, however, as much pulse processing as possible must be performed at the front end of readout electronics to avoid transferring large amounts of waveform data to a host computer for post-processing. In this paper, we present digital filtering algorithms for processing microcalorimeter pulses in real time at high count rates. The goal for these algorithms, which are being implemented in readout electronics that we are also currently developing, is to achieve sufficiently good energy resolution for most applications while being: a) simple enough to be implemented in the readout electronics; and, b) capable of processing overlapping pulses, and thus achieving much higher output count rates than those achieved by existing algorithms. Details of our algorithms are presented, and their performance is compared to that of the "optimal filter" that is currently the predominantly used pulse processing algorithm in the cryogenic-detector community.

  7. High-Rate Digital Receiver Board

    NASA Technical Reports Server (NTRS)

    Ghuman, Parminder; Bialas, Thomas; Brambora, Clifford; Fisher, David

    2004-01-01

    A high-rate digital receiver (HRDR) implemented as a peripheral component interface (PCI) board has been developed as a prototype of compact, general-purpose, inexpensive, potentially mass-producible data-acquisition interfaces between telemetry systems and personal computers. The installation of this board in a personal computer together with an analog preprocessor enables the computer to function as a versatile, highrate telemetry-data-acquisition and demodulator system. The prototype HRDR PCI board can handle data at rates as high as 600 megabits per second, in a variety of telemetry formats, transmitted by diverse phase-modulation schemes that include binary phase-shift keying and various forms of quadrature phaseshift keying. Costing less than $25,000 (as of year 2003), the prototype HRDR PCI board supplants multiple racks of older equipment that, when new, cost over $500,000. Just as the development of standard network-interface chips has contributed to the proliferation of networked computers, it is anticipated that the development of standard chips based on the HRDR could contribute to reductions in size and cost and increases in performance of telemetry systems.

  8. Differential reproductive success favours strong host preference in a highly specialized brood parasite

    PubMed Central

    De Mársico, María C; Reboreda, Juan C

    2008-01-01

    Obligate avian brood parasites show dramatic variation in the degree to which they are host specialists or host generalists. The screaming cowbird Molothrus rufoaxillaris is one of the most specialized brood parasites, using a single host, the bay-winged cowbird (Agelaioides badius) over most of its range. Coevolutionary theory predicts increasing host specificity the longer the parasite interacts with a particular avian community, as hosts evolve defences that the parasite cannot counteract. According to this view, host specificity can be maintained if screaming cowbirds avoid parasitizing potentially suitable hosts that have developed effective defences against parasitic females or eggs. Specialization may also be favoured, even in the absence of host defences, if the parasite's reproductive success in alternative hosts is lower than that in the main host. We experimentally tested these hypotheses using as alternative hosts two suitable but unparasitized species: house wrens (Troglodytes aedon) and chalk-browed mockingbirds (Mimus saturninus). We assessed host defences against parasitic females and eggs, and reproductive success of the parasite in current and alternative hosts. Alternative hosts did not discriminate against screaming cowbird females or eggs. Egg survival and hatching success were similarly high in current and alternative hosts, but the survival of parasitic chicks was significantly lower in alternative hosts. Our results indicate that screaming cowbirds have the potential to colonize novel hosts, but higher reproductive success in the current host may favour host fidelity. PMID:18647716

  9. Study on high rate MRPC for high luminosity experiments

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Huang, X.; Lv, P.; Zhu, W.; Shi, L.; Xie, B.; Cheng, J.; Li, Y.

    2014-08-01

    Multi-gap Resistive Plate Chambers (MRPC) has been used to construct time-of-flight system in the field of nuclear and particle physics, due to their high-precision timing properties, high efficiency, reliability and coverage of large area. With the increase of accelerator luminosity, MRPCs have to withstand particle fluxes up to several tens of kHz/cm2 in view of the next generation physics experiments, such as the SIS-100/300 at FAIR-CBM, SoLID at JLab and NICA at JINR. But the MRPC assembled with float glass has very low rate capability not exceeding some hundreds of Hz/cm2. Two possible solutions for increasing rate capability, one is to reduce the bulk resistivity of glass and the other is to reduce the electrode thickness. Tsinghua University has done R&D on high rate MRPC for many years. A special low resistive glass with bulk resistivity around 1010Ω.cm was developed. We also studied the rate capability changes with glass thickness. In this paper we describe the performance of low resistive glass and two kinds of high rate MRPC (Pad readout and Strip readout) tested by deuterium beams. The results show that the tolerable particle flux can reach 70 kHz/cm2. In the mean time, MRPCs assembled with three thickness (0.7 mm, 0.5 mm and 0.35 mm) of float glass were also tested with deuteron beams, the results show that the three detectors can afford particle rate up to 500 Hz/cm2, 0.75 kHz/cm2 and 3 kHz/cm2, respectively.

  10. Application of high-rate cutting tools

    NASA Astrophysics Data System (ADS)

    Moriarty, John L., Jr.

    1989-03-01

    Widespread application of the newest high-rate cutting tools to the most appropriate jobs is slowed by the sheer magnitude of developments in tool types, materials, workpiece applications, and by the rapid pace of change. Therefore, a study of finishing and roughing sizes of coated carbide inserts having a variety of geometries for single point turning was completed. The cutting tools were tested for tool life, chip quality, and workpiece surface finish at various cutting conditions with medium alloy steel. An empirical wear-life data base was established, and a computer program was developed to facilitate technology transfer, assist selection of carbide insert grades, and provide machine operating parameters. A follow-on test program was implemented suitable for next generation coated carbides, rotary cutting tools, cutting fluids, and ceramic tool materials.

  11. A high data rate recorder for astronomy

    NASA Technical Reports Server (NTRS)

    Hinteregger, H. F.; Rogers, A. E. E.; Cappallo, R. J.; Webber, J. C.; Petrachenko, W. T.

    1991-01-01

    A magnetic tape recorder developed for the special requirements of radio astronomy and geodesy is described. These requirements include a high bit packing density and long record times. The current version of this longitudinal recorder used by the Very Long Baseline Array (VLBA) records 5.5 Terabits on a 14-in diameter reel of inch-wide tape. A maximum record rate of 256 Mb/s is achieved in the VLBA configuration with one recorder operating at 4 ms and utilizing 32 of the heads in a single stack. The VLBA recorders have been tested using a longitudinal density of 2.25 fr/micron; 448 data + 56 system tracks are recorded in 14 passes, each lasting 50 min, for a total record time (at 128 Mb/s) of 12 h on 14-in diameter reel of inch-wide 13-microns-thick D1-equivalent tape.

  12. Consideration of wear rates at high velocity

    NASA Astrophysics Data System (ADS)

    Hale, Chad S.

    The development of the research presented here is one in which high velocity relative sliding motion between two bodies in contact has been considered. Overall, the wear environment is truly three-dimensional. The attempt to characterize three-dimensional wear was not economically feasible because it must be analyzed at the micro-mechanical level to get results. Thus, an engineering approximation was carried out. This approximation was based on a metallographic study identifying the need to include viscoplasticity constitutive material models, coefficient of friction, relationships between the normal load and velocity, and the need to understand wave propagation. A sled test run at the Holloman High Speed Test Track (HHSTT) was considered for the determination of high velocity wear rates. In order to adequately characterize high velocity wear, it was necessary to formulate a numerical model that contained all of the physical events present. The experimental results of a VascoMax 300 maraging steel slipper sliding on an AISI 1080 steel rail during a January 2008 sled test mission were analyzed. During this rocket sled test, the slipper traveled 5,816 meters in 8.14 seconds and reached a maximum velocity of 1,530 m/s. This type of environment was never considered previously in terms of wear evaluation. Each of the features of the metallography were obtained through micro-mechanical experimental techniques. The byproduct of this analysis is that it is now possible to formulate a model that contains viscoplasticity, asperity collisions, temperature and frictional features. Based on the observations of the metallographic analysis, these necessary features have been included in the numerical model, which makes use of a time-dynamic program which follows the movement of a slipper during its experimental test run. The resulting velocity and pressure functions of time have been implemented in the explicit finite element code, ABAQUS. Two-dimensional, plane strain models

  13. Talc lubrication at high strain rate

    NASA Astrophysics Data System (ADS)

    Doan, M.; Hirose, T.; Andreani, M.; Boullier, A.; Calugaru, D.; Boutareaud, S.

    2012-12-01

    Talc is a very soft material that has been found in small quantities in active fault zones. Its presence, even in small amount, has been demonstrated in numerous weak faults where microseismicity activity may also occur. Although talc properties have been investigated at low slip rate, its effects at coseismic rate have not been investigated. Here we show that a few weight percents of talc are enough to significantly alter the frictional behavior of natural serpentinite gouge at seismic slip rate. We performed high velocity friction experiments on wet powders mixing talc and serpentinite in varying proportions. At 1.3 m/s, pure natural serpentinite starts sliding with a high friction peak of 0.5 that falls exponentially to a steady-state value of ~0.2 over slip greater than 5 m. By introducing only 5%wt of talc, the initial peak in friction of serpentinite is cut-off: friction levels to 0.35 below 2 m of displacement before merging the exponential decay curve observed for pure serpentinite. For a larger amount of talc, friction curve becomes closer to the talc behavior, which exhibits a friction of 0.2, regardless of displacement. Increasing the amount of talc not only alters the mechanical properties of the mixture, it also changes deformation mechanism and the resulting microstructure. Below 5%wt of talc, deformation is accommodated by cataclastic comminution of serpentine grains, without any thermal decomposition. When talc is present in larger proportion, it accommodates slip with intense delamination. Principal slip zone is composed of serpentine grains smaller than 0.5 μm, 40 times smaller than the size of the initials serpentine grains. Talc grains inserted within the mixture shows extensive delamination after only 3 m of displacement. Talc lamellae are observed along the microscopic shear planes that pervade the principal slip zone and the remaining gouge. We infer that easy delamination of talc multiplies the number of talc grains and increases its

  14. Linking Reproduction and Survival Can Improve Model Estimates of Vital Rates Derived from Limited Time-Series Counts of Pinnipeds and Other Species

    PubMed Central

    Battaile, Brian C.; Trites, Andrew W.

    2013-01-01

    We propose a method to model the physiological link between somatic survival and reproductive output that reduces the number of parameters that need to be estimated by models designed to determine combinations of birth and death rates that produce historic counts of animal populations. We applied our Reproduction and Somatic Survival Linked (RSSL) method to the population counts of three species of North Pacific pinnipeds (harbor seals, Phoca vitulina richardii (Gray, 1864); northern fur seals, Callorhinus ursinus (L., 1758); and Steller sea lions, Eumetopias jubatus (Schreber, 1776))—and found our model outperformed traditional models when fitting vital rates to common types of limited datasets, such as those from counts of pups and adults. However, our model did not perform as well when these basic counts of animals were augmented with additional observations of ratios of juveniles to total non-pups. In this case, the failure of the ratios to improve model performance may indicate that the relationship between survival and reproduction is redefined or disassociated as populations change over time or that the ratio of juveniles to total non-pups is not a meaningful index of vital rates. Overall, our RSSL models show advantages to linking survival and reproduction within models to estimate the vital rates of pinnipeds and other species that have limited time-series of counts. PMID:24324541

  15. The association of culling and death rate within 30 days after calving with productivity or reproductive performance in dairy herds in Fukuoka, Southern Japan.

    PubMed

    Goto, Akira; Nakada, Ken; Katamoto, Hiromu

    2016-05-01

    The incidence of peripartum disorders in dairy herds negatively influences productivity and reproductive performance. Concrete data from local areas are helpful for explaining the importance of peripartum management to dairy farmers. This study was conducted to clarify the association of culling and death rate within 30 days after calving with productivity or reproductive performance in 179 dairy herds in Fukuoka, Southern Japan. A database was compiled from the records of the Livestock Improvement Association of Japan, the Dairy Cooperative Association and the Federation of Agricultural Mutual Relief Association. In this study, we created a comprehensive database of dairy farm production data for epidemiological analysis and used a general linear mixed model to analyze the association of culling and death rate within 30 days after calving with milk production or reproductive performance. The database can be used to describe, analyze and predict the risk of production. A cross-sectional analysis with contrasts was applied to investigate the association of cows served by AI/all cows, pregnant cows/cows served by AI, days open, milk yield and somatic cell counts with culling and death rate within 30 days after calving. The days open value significantly increased with increasing rate of culling and death within 30 days after calving (P for trend <0.001). No significant differences were found for the other comparisons. Our data suggest that proper feeding and management in the dry period may lead to improved postpartum reproductive performance in this dairy cow cohort. PMID:26666177

  16. The association of culling and death rate within 30 days after calving with productivity or reproductive performance in dairy herds in Fukuoka, Southern Japan

    PubMed Central

    GOTO, Akira; NAKADA, Ken; KATAMOTO, Hiromu

    2015-01-01

    The incidence of peripartum disorders in dairy herds negatively influences productivity and reproductive performance. Concrete data from local areas are helpful for explaining the importance of peripartum management to dairy farmers. This study was conducted to clarify the association of culling and death rate within 30 days after calving with productivity or reproductive performance in 179 dairy herds in Fukuoka, Southern Japan. A database was compiled from the records of the Livestock Improvement Association of Japan, the Dairy Cooperative Association and the Federation of Agricultural Mutual Relief Association. In this study, we created a comprehensive database of dairy farm production data for epidemiological analysis and used a general linear mixed model to analyze the association of culling and death rate within 30 days after calving with milk production or reproductive performance. The database can be used to describe, analyze and predict the risk of production. A cross-sectional analysis with contrasts was applied to investigate the association of cows served by AI/all cows, pregnant cows/cows served by AI, days open, milk yield and somatic cell counts with culling and death rate within 30 days after calving. The days open value significantly increased with increasing rate of culling and death within 30 days after calving (P for trend <0.001). No significant differences were found for the other comparisons. Our data suggest that proper feeding and management in the dry period may lead to improved postpartum reproductive performance in this dairy cow cohort. PMID:26666177

  17. Rectal temperatures, respiratory rates, production, and reproduction performances of crossbred Girolando cows under heat stress in northeastern Brazil

    NASA Astrophysics Data System (ADS)

    da Costa, Antônio Nélson Lima; Feitosa, José Valmir; Montezuma, Péricles Afonso; de Souza, Priscila Teixeira; de Araújo, Airton Alencar

    2015-11-01

    This study compared the two breed groups of Girolando (½ Holstein ½ Gyr vs. ¾ Holstein ¼ Gyr) through analysis of the percentages (stressed or non-stressed cows) of rectal temperature (RT), respiratory rate (RR) and pregnancy rate (PR), and means of production and reproduction parameters to determine the group best suited to rearing in semiarid tropical climate. The experiment was conducted at the farm, in the municipality of Umirim, State of Ceará, Brazil. Two hundred and forty cows were used in a 2 × 2 factorial study; 120 of each group were kept under an intensive system during wet and dry seasons. The environmental parameters obtained were relative humidity (RH), air temperature (AT), and the temperature and humidity index (THI). Pregnancy diagnosis (PD) was determined by ultrasonography 30 days after artificial insemination (AI). The milk production of each cow was recorded with automated milkings in the farm. The variables were expressed as mean and standard error, evaluated by ANOVA at 5 % probability using the GLM procedure of SAS. Chi-square test at 5 % probability was applied to data of RT, RR, pregnancy rate (PR), and the number of AIs to obtain pregnancy. The majority of ½ Holstein cows showed mean values of RT and RR within the normal range in both periods and shifts. Most animals of the ¾ Holstein group exhibited the RR means above normal during the afternoon in the rainy and dry periods and RT means above normal during the afternoon in the dry period. After analyses, ½ Holstein crossbred cows are more capable of thermoregulating than ¾ Holstein cows under conditions of thermal stress, and the dry period was more impacting for bovine physiology with significant changes in physiological parameters, even for the first breed group. Knowledge of breed groups adapted to climatic conditions of northeastern Brazil can directly assist cattle farmers in selecting animals best adapted for forming herds.

  18. Rectal temperatures, respiratory rates, production, and reproduction performances of crossbred Girolando cows under heat stress in northeastern Brazil.

    PubMed

    da Costa, Antônio Nélson Lima; Feitosa, José Valmir; Montezuma, Péricles Afonso; de Souza, Priscila Teixeira; de Araújo, Airton Alencar

    2015-11-01

    This study compared the two breed groups of Girolando (½ Holstein ½ Gyr vs. ¾ Holstein ¼ Gyr) through analysis of the percentages (stressed or non-stressed cows) of rectal temperature (RT), respiratory rate (RR) and pregnancy rate (PR), and means of production and reproduction parameters to determine the group best suited to rearing in semiarid tropical climate. The experiment was conducted at the farm, in the municipality of Umirim, State of Ceará, Brazil. Two hundred and forty cows were used in a 2 × 2 factorial study; 120 of each group were kept under an intensive system during wet and dry seasons. The environmental parameters obtained were relative humidity (RH), air temperature (AT), and the temperature and humidity index (THI). Pregnancy diagnosis (PD) was determined by ultrasonography 30 days after artificial insemination (AI). The milk production of each cow was recorded with automated milkings in the farm. The variables were expressed as mean and standard error, evaluated by ANOVA at 5% probability using the GLM procedure of SAS. Chi-square test at 5% probability was applied to data of RT, RR, pregnancy rate (PR), and the number of AIs to obtain pregnancy. The majority of ½ Holstein cows showed mean values of RT and RR within the normal range in both periods and shifts. Most animals of the ¾ Holstein group exhibited the RR means above normal during the afternoon in the rainy and dry periods and RT means above normal during the afternoon in the dry period. After analyses, ½ Holstein crossbred cows are more capable of thermoregulating than ¾ Holstein cows under conditions of thermal stress, and the dry period was more impacting for bovine physiology with significant changes in physiological parameters, even for the first breed group. Knowledge of breed groups adapted to climatic conditions of northeastern Brazil can directly assist cattle farmers in selecting animals best adapted for forming herds. PMID:25702060

  19. High rate PLD of diamond-like-carbon utilizing high repetition rate visible lasers

    SciTech Connect

    McLean, W. II; Fehring, E.J.; Dragon, E.P.; Warner, B.E.

    1994-09-15

    Pulsed Laser Deposition (PLD) has been shown to be an effective method for producing a wide variety of thin films of high-value-added materials. The high average powers and high pulse repetition frequencies of lasers under development at LLNL make it possible to scale-up PLD processes that have been demonstrated in small systems in a number of university, government, and private laboratories to industrially meaningful, economically feasible technologies. A copper vapor laser system at LLNL has been utilized to demonstrate high rate PLD of high quality diamond-like-carbon (DLC) from graphite targets. The deposition rates for PLD obtained with a 100 W laser were {approx} 2000 {mu}m{center_dot}cm{sup 2}/h, or roughly 100 times larger than those reported by chemical vapor deposition (CVD) or physical vapor deposition (PVD) methods. Good adhesion of thin (up to 2 pm) films has been achieved on a small number of substrates that include SiO{sub 2} and single crystal Si. Present results indicate that the best quality DLC films can be produced at optimum rates at power levels and wavelengths compatible with fiber optic delivery systems. If this is also true of other desirable coating systems, this PLD technology could become an extremely attractive industrial tool for high value added coatings.

  20. Nesting ecology and reproductive rate of the red-winged blackbird in tidal marshes of the upper Chesapeake Bay region

    USGS Publications Warehouse

    Meanley, B.; Webb, J.S.

    1963-01-01

    The nesting ecology and reproductive rate of the polygynous red-winged blackbird, Agelaius phoeniceus, were studied in the tidal marshes of Maryland during the period of 1958 through 1961. Sixteen nesting colonies were located in six major marsh communities of the Eastern Shore and were visited approximately twice a week from late April to mid-August. The average clutch size for 537 clutches was 3.3 eggs, with a range of 2 to 5 eggs. The ratio of territorial males to nesting females was 1:1.9. There was direct evidence of double broods by four females. The average number of young produced was 4.2 per breeding female or 8.1 per breeding male. Nesting success for the total of 675 active nests was 57%, with a range from 38% to 69% in the colonies. Robust plants that held constant form throughout the nesting season supported 95% of the nests, and the success of these nests was 58%; in contrast, non-robust plants supported only 5% of the nests, and success of this group of nests was only 26%. Nesting success varied with height from ground: 45% for nests less than 2 feet from the ground, 55% for those 2 to 4 feet, and 62% for those more than 4 feet. Histories of 749 nests were summarized by stages: 749 newly built, 675 with eggs, 424 with nestlings, and 388 with fledging young.

  1. High variance in reproductive success generates a false signature of a genetic bottleneck in populations of constant size: a simulation study

    PubMed Central

    2013-01-01

    Background Demographic bottlenecks can severely reduce the genetic variation of a population or a species. Establishing whether low genetic variation is caused by a bottleneck or a constantly low effective number of individuals is important to understand a species’ ecology and evolution, and it has implications for conservation management. Recent studies have evaluated the power of several statistical methods developed to identify bottlenecks. However, the false positive rate, i.e. the rate with which a bottleneck signal is misidentified in demographically stable populations, has received little attention. We analyse this type of error (type I) in forward computer simulations of stable populations having greater than Poisson variance in reproductive success (i.e., variance in family sizes). The assumption of Poisson variance underlies bottleneck tests, yet it is commonly violated in species with high fecundity. Results With large variance in reproductive success (Vk ≥ 40, corresponding to a ratio between effective and census size smaller than 0.1), tests based on allele frequencies, allelic sizes, and DNA sequence polymorphisms (heterozygosity excess, M-ratio, and Tajima’s D test) tend to show erroneous signals of a bottleneck. Similarly, strong evidence of population decline is erroneously detected when ancestral and current population sizes are estimated with the model based method MSVAR. Conclusions Our results suggest caution when interpreting the results of bottleneck tests in species showing high variance in reproductive success. Particularly in species with high fecundity, computer simulations are recommended to confirm the occurrence of a population bottleneck. PMID:24131797

  2. A three generation reproduction study with Sprague-Dawley rats consuming high-amylose transgenic rice.

    PubMed

    Zhou, Xing Hua; Dong, Ying; Zhao, Yan Sheng; Xiao, Xiang; Wang, Yun; He, Yuan Qing; Liu, Qiao Quan

    2014-12-01

    The transgenic rice line (TRS) enriched with amylose and resistant starch (RS) was developed by antisense RNA inhibition of starch-branching enzymes. Cereal starch with high amylose has a great benefit on human health through its resistant starch. In order to evaluate the effect of transgenic rice on rats, the rats were fed diets containing 70% TRS rice flour, its near-isogenic rice flour or the standard diet as the control through three generations. In the present study, clinical performance, reproductive capacity and pathological responses including body weight, food consumption, reproductive data, hematological parameters, serum chemistry components, organ relative weights and histopathology were examined. Some statistically significant differences were observed in rats consuming the high amylose rice diet when compared to rats fed the near-isogenic control rice diet or the conventional (non-rice) standard diet. These differences were generally of small magnitude, appeared to be random in nature, and were within normal limits for the strain of rat used, and were therefore not considered to be biologically meaningful or treatment related. PMID:25194626

  3. Cryptic diversity, high host specificity and reproductive synchronization in army ant-associated Vatesus beetles.

    PubMed

    von Beeren, Christoph; Maruyama, Munetoshi; Kronauer, Daniel J C

    2016-02-01

    Army ants and their arthropod symbionts represent one of the most species-rich animal associations on Earth, and constitute a fascinating example of diverse host-symbiont interaction networks. However, despite decades of research, our knowledge of army ant symbionts remains fragmentary due to taxonomic ambiguity and the inability to study army ants in the laboratory. Here, we present an integrative approach that allows us to reliably determine species boundaries, assess biodiversity, match different developmental stages and sexes, and to study the life cycles of army ant symbionts. This approach is based on a combination of community sampling, DNA barcoding, morphology and physiology. As a test case, we applied this approach to the staphylinid beetle genus Vatesus and its different Eciton army ant host species at La Selva Biological Station, Costa Rica. DNA barcoding led to the discovery of cryptic biodiversity and, in combination with extensive community sampling, revealed strict host partitioning with no overlap in host range. Using DNA barcoding, we were also able to match the larval stages of all focal Vatesus species. In combination with studies of female reproductive physiology, this allowed us to reconstruct almost the complete life cycles of the different beetle species. We show that Vatesus beetles are highly adapted to the symbiosis with army ants, in that their reproduction and larval development are synchronized with the stereotypical reproductive and behavioural cycles of their host colonies. Our approach can now be used to study army ant-symbiont communities more broadly, and to obtain novel insights into co-evolutionary and ecological dynamics in species-rich host-symbiont systems. PMID:26618779

  4. Early and delayed reproductive death in human cells exposed to high energy iron-ion beams

    NASA Astrophysics Data System (ADS)

    Bettega, D.; Calzolari, P.; Doneda, L.; Durante, M.; Tallone, L.

    For radiation protection of the astronauts it is important to know both the acute and the late effects of charged particles. Iron is the most abundant high charge and energy (HZE) specie in galactic cosmic radiation. (HZE) ions are considered to be the major contributors to equivalent dose in space, but the Relative Biological Effectiveness of HZE particles has large uncertainties, expecially for late effects. We have determined early and delayed reproductive death in human fibroblast cells (AG1522) exposed to iron ion beams of energies between 0.2 and 1 GeV/n. The cells were irradiated at the HIMAC accelerator in Chiba (0.2 and 0.5 GeV/n) and at the AGS accelerator at the NASA Space Radiation Laboratory in Brookhaven (1 GeV/n). For each beam the dose--effect curves were measured at least twice in the dose range between 0.5 and 2 Gy. 60 Co gamma rays were used as reference radiation. The following results were obtained: 1) the 1 GeV/n beam effectiveness for inactivation of the AG1522 cells is higher than that of any other beam. 2) the progeny of the irradiated cells show the presence of delayed damage in the form of reproductive death for all the beams with the 1 GeV/n being the most effective. 3) the relative biological effectiveness of the iron beams is higher for delayed compared to early reproductive death. A comparison with preliminary results obtained with 970 MeV/n Ti and 490 MeV/n Si ions will be also reported .

  5. High-pressure, High-strain-rate Materials Effects

    SciTech Connect

    Kalantar, D; Belak, J; Bringa, E; Budil, K; Colvin, J; Kumar, M; Meyers, M; Rosolankova, K; Rudd, R; Schneider, M; Stolken, J; Wark, J

    2004-03-04

    A 3-year LDRD-ER project to study the response of shocked materials at high pressure and high strain rate has concluded. This project involved a coordinated effort to study single crystal samples that were shock loaded by direct laser irradiation, in-situ and post-recovery measurements, and molecular dynamics and continuum modeling. Laser-based shock experiments have been conducted to study the dynamic response of materials under shock loading materials at a high strain-rate. Experiments were conducted at pressures above the published Hugoniot Elastic Limit (HEL). The residual deformation present in recovered samples was characterized by transmission electron microscopy, and the response of the shocked lattice during shock loading was measured by in-situ x-ray diffraction. Static film and x-ray streak cameras recorded x-rays diffracted from lattice planes of Cu and Si both parallel and perpendicular to the shock direction. Experiments were also conducted using a wide-angle detector to record x-rays diffracted from multiple lattice planes simultaneously. This data showed uniaxial compression of Si (100) along the shock direction and 3-dimensional compression of Cu (100). In the case of the Si diffraction, there was a multiple wave structure observed. We present results of shocked Si and Cu obtained with a new large angle diffraction diagnostic, and discuss the results in the context of detailed molecular dynamics simulations and post-processing.

  6. High voltage high repetition rate pulse using Marx topology

    NASA Astrophysics Data System (ADS)

    Hakki, A.; Kashapov, N.

    2015-06-01

    The paper describes Marx topology using MOSFET transistors. Marx circuit with 10 stages has been done, to obtain pulses about 5.5KV amplitude, and the width of the pulses was about 30μsec with a high repetition rate (PPS > 100), Vdc = 535VDC is the input voltage for supplying the Marx circuit. Two Ferrite ring core transformers were used to control the MOSFET transistors of the Marx circuit (the first transformer to control the charging MOSFET transistors, the second transformer to control the discharging MOSFET transistors).

  7. Dislocation Mechanics of High-Rate Deformations

    NASA Astrophysics Data System (ADS)

    Armstrong, Ronald W.; Li, Qizhen

    2015-10-01

    Four topics associated with constitutive equation descriptions of rate-dependent metal plastic deformation behavior are reviewed in honor of previous research accomplished on the same issues by Professor Marc Meyers along with colleagues and students, as follow: (1) increasing strength levels attributed to thermally activated dislocation migration at higher loading rates; (2) inhomogeneous adiabatic shear banding; (3) controlling mechanisms of deformation in shock as compared with shock-less isentropic compression experiments and (4) Hall-Petch-based grain size-dependent strain rate sensitivities exhibited by nanopolycrystalline materials. Experimental results are reviewed on the topics for a wide range of metals.

  8. Effects of folic acid and vitamin B12 supplementation on culling rate, diseases, and reproduction in commercial dairy herds.

    PubMed

    Duplessis, M; Girard, C L; Santschi, D E; Laforest, J-P; Durocher, J; Pellerin, D

    2014-01-01

    This study was undertaken to determine the effect of a combined folic acid and vitamin B12 supplement given in early lactation on culling rate, metabolic disorders and other diseases, and reproduction in commercial dairy herds. A total of 805 cows (271 primiparous and 534 multiparous cows) in 15 commercial dairy herds were involved. Every 2mo from February to December 2010 and within each herd, cows were assigned according to parity, previous 305-d milk production, and calving interval to 5mL of either (1) saline 0.9% NaCl (control group) or (2) 320mg of folic acid + 10mg of vitamin B12 (vitamin group). Treatments were administered weekly by intramuscular injections starting 3wk before the expected calving date until 8wk after parturition. A total of 221 cows were culled before the next dry period. Culling rate was not affected by treatment and was 27.5%; culling rate was greater for multiparous (32.2%) than for primiparous cows (18.8%). Within the first 60d in milk (DIM), 47 cows were culled, representing 21.3% of total culling, and no treatment effect was noted. Ketosis incidence based on a threshold ≥100µmol/L of β-hydroxybutyrate in milk was 38.3±2.9% for the vitamin group and 41.8±3.0% for the control group and was not affected by treatment. The combined supplement of folic acid and vitamin B12 did not decrease incidence of retained placenta, displaced abomasum, milk fever, metritis, or mastitis. However, the incidence of dystocia decreased by 50% in multiparous cows receiving the vitamin supplement, although no effect was observed in primiparous cows. The first breeding postpartum for multiparous cows occurred 3.8d earlier with the vitamin supplement compared with controls, whereas no treatment effect was seen for primiparous cows. Days open, first- and second-breeding conception rates, number of breedings per conception, and percentage of cows pregnant at 150 DIM were not affected by treatment. The reduced percentage of dystocia combined with the

  9. HIgh Rate X-ray Fluorescence Detector

    SciTech Connect

    Grudberg, Peter Matthew

    2013-04-30

    The purpose of this project was to develop a compact, modular multi-channel x-ray detector with integrated electronics. This detector, based upon emerging silicon drift detector (SDD) technology, will be capable of high data rate operation superior to the current state of the art offered by high purity germanium (HPGe) detectors, without the need for liquid nitrogen. In addition, by integrating the processing electronics inside the detector housing, the detector performance will be much less affected by the typically noisy electrical environment of a synchrotron hutch, and will also be much more compact than current systems, which can include a detector involving a large LN2 dewar and multiple racks of electronics. The combined detector/processor system is designed to match or exceed the performance and features of currently available detector systems, at a lower cost and with more ease of use due to the small size of the detector. In addition, the detector system is designed to be modular, so a small system might just have one detector module, while a larger system can have many you can start with one detector module, and add more as needs grow and budget allows. The modular nature also serves to simplify repair. In large part, we were successful in achieving our goals. We did develop a very high performance, large area multi-channel SDD detector, packaged with all associated electronics, which is easy to use and requires minimal external support (a simple power supply module and a closed-loop water cooling system). However, we did fall short of some of our stated goals. We had intended to base the detector on modular, large-area detectors from Ketek GmbH in Munich, Germany; however, these were not available in a suitable time frame for this project, so we worked instead with pnDetector GmbH (also located in Munich). They were able to provide a front-end detector module with six 100 m^2 SDD detectors (two monolithic arrays of three elements each) along with

  10. Bipolar high-repetition-rate high-voltage nanosecond pulser

    SciTech Connect

    Tian Fuqiang; Wang Yi; Shi Hongsheng; Lei Qingquan

    2008-06-15

    The pulser designed is mainly used for producing corona plasma in waste water treatment system. Also its application in study of dielectric electrical properties will be discussed. The pulser consists of a variable dc power source for high-voltage supply, two graded capacitors for energy storage, and the rotating spark gap switch. The key part is the multielectrode rotating spark gap switch (MER-SGS), which can ensure wider range modulation of pulse repetition rate, longer pulse width, shorter pulse rise time, remarkable electrical field distortion, and greatly favors recovery of the gap insulation strength, insulation design, the life of the switch, etc. The voltage of the output pulses switched by the MER-SGS is in the order of 3-50 kV with pulse rise time of less than 10 ns and pulse repetition rate of 1-3 kHz. An energy of 1.25-125 J per pulse and an average power of up to 10-50 kW are attainable. The highest pulse repetition rate is determined by the driver motor revolution and the electrode number of MER-SGS. Even higher voltage and energy can be switched by adjusting the gas pressure or employing N{sub 2} as the insulation gas or enlarging the size of MER-SGS to guarantee enough insulation level.

  11. High data rate systems for the future

    NASA Technical Reports Server (NTRS)

    Chitwood, John

    1991-01-01

    Information systems in the next century will transfer data at rates that are much greater than those in use today. Satellite based communication systems will play an important role in networking users. Typical data rates; use of microwave, millimeter wave, or optical systems; millimeter wave communication technology; modulators/exciters; solid state power amplifiers; beam waveguide transmission systems; low noise receiver technology; optical communication technology; and the potential commercial applications of these technologies are discussed.

  12. High rates of molecular evolution in hantaviruses.

    PubMed

    Ramsden, Cadhla; Melo, Fernando L; Figueiredo, Luiz M; Holmes, Edward C; Zanotto, Paolo M A

    2008-07-01

    Hantaviruses are rodent-borne Bunyaviruses that infect the Arvicolinae, Murinae, and Sigmodontinae subfamilies of Muridae. The rate of molecular evolution in the hantaviruses has been previously estimated at approximately 10(-7) nucleotide substitutions per site, per year (substitutions/site/year), based on the assumption of codivergence and hence shared divergence times with their rodent hosts. If substantiated, this would make the hantaviruses among the slowest evolving of all RNA viruses. However, as hantaviruses replicate with an RNA-dependent RNA polymerase, with error rates in the region of one mutation per genome replication, this low rate of nucleotide substitution is anomalous. Here, we use a Bayesian coalescent approach to estimate the rate of nucleotide substitution from serially sampled gene sequence data for hantaviruses known to infect each of the 3 rodent subfamilies: Araraquara virus (Sigmodontinae), Dobrava virus (Murinae), Puumala virus (Arvicolinae), and Tula virus (Arvicolinae). Our results reveal that hantaviruses exhibit short-term substitution rates of 10(-2) to 10(-4) substitutions/site/year and so are within the range exhibited by other RNA viruses. The disparity between this substitution rate and that estimated assuming rodent-hantavirus codivergence suggests that the codivergence hypothesis may need to be reevaluated. PMID:18417484

  13. Cheetah: A high frame rate, high resolution SWIR image camera

    NASA Astrophysics Data System (ADS)

    Neys, Joel; Bentell, Jonas; O'Grady, Matt; Vermeiren, Jan; Colin, Thierry; Hooylaerts, Peter; Grietens, Bob

    2008-10-01

    A high resolution, high frame rate InGaAs based image sensor and associated camera has been developed. The sensor and the camera are capable of recording and delivering more than 1700 full 640x512pixel frames per second. The FPA utilizes a low lag CTIA current integrator in each pixel, enabling integration times shorter than one microsecond. On-chip logics allows for four different sub windows to be read out simultaneously at even higher rates. The spectral sensitivity of the FPA is situated in the SWIR range [0.9-1.7 μm] and can be further extended into the Visible and NIR range. The Cheetah camera has max 16 GB of on-board memory to store the acquired images and transfer the data over a Gigabit Ethernet connection to the PC. The camera is also equipped with a full CameralinkTM interface to directly stream the data to a frame grabber or dedicated image processing unit. The Cheetah camera is completely under software control.

  14. Reproductive hacking

    PubMed Central

    Dustin Rubinstein, C; Wolfner, Mariana F

    2014-01-01

    Seminal proteins are critical for reproductive success in all animals that have been studied. Although seminal proteins have been identified in many taxa, and female reproductive responses to receipt of these proteins have been documented in several, little is understood about the mechanisms by which seminal proteins affect female reproductive physiology. To explore this topic, we investigated how a Drosophila seminal protein, ovulin, increases ovulation rate in mated females. Ovulation is a relatively simple physiological process, with known female regulators: previous studies have shown that ovulation rate is promoted by the neuromodulator octopamine (OA) in D. melanogaster and other insects. We found that ovulin stimulates ovulation by increasing OA signaling in the female. This finding supports a model in which a male seminal protein acts through “hacking” a well-conserved, regulatory system females use to adjust reproductive output, rather than acting downstream of female mechanisms of control or in parallel pathways altogether. We also discuss similarities between 2 forms of intersexual control of behavior through chemical communication: seminal proteins and pheromones. PMID:25483253

  15. Factors Associated with the Reproductive Health Risk Behavior of High School Students in the Republic of the Marshall Islands

    ERIC Educational Resources Information Center

    Suzuki, Keiko; Motohashi, Yutaka; Kaneko, Yoshihiro

    2006-01-01

    This study revealed factors associated with reproductive health risk behavior among high school students in the Republic of the Marshall Islands. The survey was conducted among high school students from grades 9 through 12 at 2 schools in Majuro, the capital of the Marshall Islands. The questions asked inquired about knowledge, attitude, and…

  16. Smoking Rates Still High in Some Racial Groups, CDC Reports

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_160256.html Smoking Rates Still High in Some Racial Groups, CDC ... lot of progress in getting Americans to stop smoking, some groups still have high smoking rates, a ...

  17. Development of an image capturing system for the reproduction of high-fidelity color

    NASA Astrophysics Data System (ADS)

    Ejaz, Tahseen; Shoichi, Yokoi; Horiuchi, Tomohiro; Yokota, Tetsuya; Takaya, Masanori; Ohashi, Gosuke; Shimodaira, Yoshifumi

    2005-01-01

    An image capturing system for the reproduction of high-fidelity color color was developed and a set of three optical filters were designed for this purpose. Simulation was performed on the SOCS database containing the spectral reflectance data of various objects in the range of wavelength of 400nm ~ 700nm in order to calculate the CIELAB color difference ΔEab. The average color difference was found to be 1.049. The camera was mounted with the filters and color photographs of all the 24 color patches of the Macbeth chart were taken. The measured tristimulus values of the patches were compared with those of the digital images captured by the camera. The average ΔEab was found to be 5.916.

  18. Development of an image capturing system for the reproduction of high-fidelity color

    NASA Astrophysics Data System (ADS)

    Ejaz, Tahseen; Shoichi, Yokoi; Horiuchi, Tomohiro; Yokota, Tetsuya; Takaya, Masanori; Ohashi, Gosuke; Shimodaira, Yoshifumi

    2004-12-01

    An image capturing system for the reproduction of high-fidelity color color was developed and a set of three optical filters were designed for this purpose. Simulation was performed on the SOCS database containing the spectral reflectance data of various objects in the range of wavelength of 400nm ~ 700nm in order to calculate the CIELAB color difference ΔEab. The average color difference was found to be 1.049. The camera was mounted with the filters and color photographs of all the 24 color patches of the Macbeth chart were taken. The measured tristimulus values of the patches were compared with those of the digital images captured by the camera. The average ΔEab was found to be 5.916.

  19. Reproductive parameters and oxidative stress status of male rats fed with low and high salt diet

    PubMed Central

    Iranloye, Bolanle O.; Oludare, Gabriel O.; Morakinyo, Ayodele O.; Esume, Naomi A.; Ekeh, Lucy C.

    2013-01-01

    BACKGROUND: Deficiency of minerals and micronutrients has been reported to impair the process of spermatogenesis. Historically, salt has been used by women on their husbands to increase their libido, however, the role of salt diet on sperm parameters are yet to be ascertained. AIM: The present study was designed to determine the effect of low and high salt diet on sperm parameters, oxidative status and reproductive hormone levels of male rats. MATERIALS AND METHODS: A total of 18 rats were divided into three groups: Group I: (control) received 0.3% salt diet, Group II: low salt (received 0.14% salt diet) and Group III: high salt (received 8% salt diet). All animals were treated for 6 weeks; after which epididymal sperm parameters; oxidative stress markers (malondialdehyde, glutathione, catalase and superoxide dismutase) in the testes and epididymal tissues, as well as follicle stimulating hormone (FSH), luteinizing hormone (LH) and testosterone levels were determined. RESULTS: The results showed decreased sperm count in the low salt diet rats while increased sperm count was observed in the high salt diet treated rats. Both low salt and high salt diet fed rats exhibited increased abnormal sperm cells and increased epididymal oxidative stress when compared with their respective control. FSH and testosterone levels were increased in the high salt fed rats while LH level was decreased when compared with the control values. CONCLUSION: This study suggests that both low and high salt diet play a negative role in the fertility of male rats. PMID:24672168

  20. High frame rate fluorescence lifetime imaging

    NASA Astrophysics Data System (ADS)

    Agronskaia, A. V.; Tertoolen, L.; Gerritsen, H. C.

    2003-07-01

    A fast time-domain based fluorescence lifetime imaging (FLIM) microscope is presented that can operate at frame rates of hundreds of frames per second. A beam splitter in the detection path of a wide-field fluorescence microscope divides the fluorescence in two parts. One part is optically delayed with respect to the other. Both parts are viewed with a single time-gated intensified CCD camera with a gate width of 5 ns. The fluorescence lifetime image is obtained from the ratio of these two images. The fluorescence lifetime resolution of the FLIM microscope is verified both with dye solutions and fluorescent latex beads. The fluorescence lifetimes obtained from the reference specimens are in good agreement with values obtained from time correlated single photon counting measurements on the same specimens. The acquisition speed of the FLIM system is evaluated with a measurement of the calcium fluxes in neonatal rat myocytes stained with the calcium probe Oregon Green 488-Bapta. Fluorescence lifetime images of the calcium fluxes related to the beating of the myocytes are acquired with frame rates of up to 100 Hz.

  1. High Count Rate Electron Probe Microanalysis

    PubMed Central

    Geller, Joseph D.; Herrington, Charles

    2002-01-01

    Reducing the measurement uncertainty of quantitative analyses made using electron probe microanalyzers (EPMA) requires a careful study of the individual uncertainties from each definable step of the measurement. Those steps include measuring the incident electron beam current and voltage, knowing the angle between the electron beam and the sample (takeoff angle), collecting the emitted x rays from the sample, comparing the emitted x-ray flux to known standards (to determine the k-ratio) and transformation of the k-ratio to concentration using algorithms which includes, as a minimum, the atomic number, absorption, and fluorescence corrections. This paper discusses the collection and counting of the emitted x rays, which are diffracted into the gas flow or sealed proportional x-ray detectors. The representation of the uncertainty in the number of collected x rays collected reduces as the number of counts increase. The uncertainty of the collected signal is fully described by Poisson statistics. Increasing the number of x rays collected involves either counting longer or at a higher counting rate. Counting longer means the analysis time increases and may become excessive to get to the desired uncertainty. Instrument drift also becomes an issue. Counting at higher rates has its limitations, which are a function of the detector physics and the detecting electronics. Since the beginning of EPMA analysis, analog electronics have been used to amplify and discriminate the x-ray induced ionizations within the proportional counter. This paper will discuss the use of digital electronics for this purpose. These electronics are similar to that used for energy dispersive analysis of x rays with either Si(Li) or Ge(Li) detectors except that the shaping time constants are much smaller. PMID:27446749

  2. Infant mortality rates declining, but still high.

    PubMed

    Hoffman, M

    1992-10-01

    Family planning can improve infant survival. Specifically, use of family planning methods can minimize family size, increase birth spacing, and reduce the likelihood of pregnancy for teenagers and women aged 40 or older. Immunizations and oral rehydration are responsible for the falling infant mortality rats since 1977 in developing countries, especially among 1-12 month old infants. Yet, neonatal mortality in developing countries had not changed. WHO intends to step up efforts to improve newborn survival. Accurate data are needed, however. Even in developed countries which keep good statistics, infant mortality bias exists. For example, in Japan, some infant deaths are called fetal deaths. In developing countries, much of the data come from hospitals, yet most birth do not occur in hospitals. Even in surveys, bias exists, such as problems with recall. Many researchers use traditional birth attendants (TBAs) to follow up on all births in an area which may eliminate some biases. Such a prospective and longitudinal study in Trairi county in northeastern Brazil shows the infant mortality rate to be less than half of the official rate (65 vs. 142). The major causes of infant death in developed countries, which tends to occur in the neonatal period, are low birth weight, prematurity, birth complications, and congenital defects; developing countries; they are vaccine preventable infectious diseases, diarrhea and dehydration, and respiratory illnesses, all complicated by malnutrition. To make further strides in reducing infant mortality, public health workers must concentrate on the neonatal period. Training TBAs in sterile techniques, appropriate technology, resuscitation of infants, and identification of potential problems is a positive step. Yet, unpredictable conditions (e.g., AIDS) exist and/or will arise which erode improvements. For example, in Nicaragua, within 1 year after the new government introduced health budget cuts which resulted in the poor paying for

  3. HIGH-THROUGHPUT CELLULAR ASSAYS FOR MODELING TOXICITY IN THE FISH REPRODUCTIVE SYSTEM

    EPA Science Inventory

    The most important benefit of this project is the experimental evaluation of all essential steps in the development and testing of adverse outcome pathways (AOP) for a diverse set of reproductive and non-reproductive toxicants. In contrast to human testing and the toxicity pat...

  4. Research on characteristic spectrum extracting and matching for high-fidelity reproduction.

    PubMed

    Yang, Sheng-wei; Liu, Zhen; Wu, Ming-guang; Zhang, Zhen-jie

    2014-06-01

    Reconstructing the spectrum rapidly and accurately is the key to the research on high-fidelity reproduction. A characteristic spectrum extracting and matching method for high-fidelity printing is proposed aiming at the problem of complex conversion between spectrum and ink combination caused by multi-color. The method filters and extracts feature bands of primary ink through derivative spectrum, and a characteristic spectrum multi-threshold coding method is proposed. Considering the problem of subarea judgment in hi-fi printing, an average derivative spectrum is taken as characteristic spectrum of each subarea and a spectrum matching method between target spectrum and average derivative spectrum of sub-spaces is proposed. The results show that the feature bands extracted can represent spectral characteristic of primary color significantly and the precision of color conversion model based on feature bands is higher than the model based on full bands. The spectrum matching method can achieve a high accuracy in sub-space judgments and greatly improve the efficiency of color convention. The spectrum extracting and matching method has the high practicability. PMID:25358178

  5. High-rate counting efficiency of VLPC

    SciTech Connect

    Hogue, H.H.

    1998-11-01

    A simple model is applied to describe dependencies of Visible Light Photon Counter (VLPC) characteristics on temperature and operating voltage. Observed counting efficiency losses at high illumination, improved by operating at higher temperature, are seen to be a consequence of de-biasing within the VLPC structure. A design improvement to minimize internal de-biasing for future VLPC generations is considered. {copyright} {ital 1998 American Institute of Physics.}

  6. High performance interconnection between high data rate networks

    NASA Technical Reports Server (NTRS)

    Foudriat, E. C.; Maly, K.; Overstreet, C. M.; Zhang, L.; Sun, W.

    1992-01-01

    The bridge/gateway system needed to interconnect a wide range of computer networks to support a wide range of user quality-of-service requirements is discussed. The bridge/gateway must handle a wide range of message types including synchronous and asynchronous traffic, large, bursty messages, short, self-contained messages, time critical messages, etc. It is shown that messages can be classified into three basic classes, synchronous and large and small asynchronous messages. The first two require call setup so that packet identification, buffer handling, etc. can be supported in the bridge/gateway. Identification enables resequences in packet size. The third class is for messages which do not require call setup. Resequencing hardware based to handle two types of resequencing problems is presented. The first is for a virtual parallel circuit which can scramble channel bytes. The second system is effective in handling both synchronous and asynchronous traffic between networks with highly differing packet sizes and data rates. The two other major needs for the bridge/gateway are congestion and error control. A dynamic, lossless congestion control scheme which can easily support effective error correction is presented. Results indicate that the congestion control scheme provides close to optimal capacity under congested conditions. Under conditions where error may develop due to intervening networks which are not lossless, intermediate error recovery and correction takes 1/3 less time than equivalent end-to-end error correction under similar conditions.

  7. High-deposition-rate ceramics synthesis

    SciTech Connect

    Allendorf, M.D.; Osterheld, T.H.; Outka, D.A.

    1995-05-01

    Parallel experimental and computational investigations are conducted in this project to develop validated numerical models of ceramic synthesis processes. Experiments are conducted in the High-Temperature Materials Synthesis Laboratory in Sandia`s Combustion Research Facility. A high-temperature flow reactor that can accommodate small preforms (1-3 cm diameter) generates conditions under which deposition can be observed, with flexibility to vary both deposition temperature (up to 1500 K) and pressure (as low as 10 torr). Both mass spectrometric and laser diagnostic probes are available to provide measurements of gas-phase compositions. Experiments using surface analytical techniques are also applied to characterize important processes occuring on the deposit surface. Computational tools developed through extensive research in the combustion field are employed to simulate the chemically reacting flows present in typical industrial reactors. These include the CHEMKIN and Surface-CHEMKIN suites of codes, which permit facile development of complex reaction mechanisms and vastly simplify the implementation of multi-component transport and thermodynamics. Quantum chemistry codes are also used to estimate thermodynamic and kinetic data for species and reactions for which this information is unavailable.

  8. Infection of United States swine with a Chinese highly pathogenic strain of porcine reproductive and respiratory syndrome virus

    Technology Transfer Automated Retrieval System (TEKTRAN)

    To assess the pathogenic effects of Type 2 highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) on healthy 10-week old commercial swine in the United States, viral kinetics and resultant disease caused by intranasal inoculation of such virus rescued from an infectious clo...

  9. The vOTU domain of highly-pathogenic porcine reproductive and respiratory syndrome virus displays a differential substrate preference

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Arterivirus genus member Porcine reproductive and respiratory syndrome virus (PRRSV) causes an economically devastating disease that presents global concerns to the pork industry, which have been exacerbated by the emergence of a highly pathogenic PRRSV strain (HP-PRRSV) in China and Southeast Asia....

  10. High rates of nonbreeding adult bald eagles in southeastern Alaska

    SciTech Connect

    Hansen, A.J.; Hodges, J.I. Jr.

    1985-01-01

    Present knowledge of bald eagle (Haliaeetus leucocephalus) demography is derived primarily from populations in environments that have been drastically altered by man. Most reproductive studies were done in the 1960's and 1970's when chemical toxins were inhibiting bald eagle productivity. Earlier, the removal of old-growth forests and decimation of anadromous fish runs by Euro-Americans may have greatly reduced bald eagle abundance from presettlement levels. Historical trends in this species are of interest because fundamental differences may exist between populations in pristine and man-altered environments. One difference may be breeding rate. Surpluses of nonbreeding adult bald eagles during the nesting season are rarely mentioned in the literature. Most surveys of reproductive success focus exclusively on eagles at nest sites, which assumes nearly all adults attempt to breed each year. The authors report that a majority of adults in the relatively pristine habitats of southeastern Alaska do not breed annually. This finding is important because if surpluses of non-breeding adults are a natural feature of the population, then hypotheses on density dependent population regulation and the evolution of delayed maturation are suggested. If, on the other hand, the abundance of nonbreeders is an artifact of recent environmental perturbations, serious population declines may occur in southeastern Alaska.

  11. The Effect of Minimum Wage Rates on High School Completion

    ERIC Educational Resources Information Center

    Warren, John Robert; Hamrock, Caitlin

    2010-01-01

    Does increasing the minimum wage reduce the high school completion rate? Previous research has suffered from (1. narrow time horizons, (2. potentially inadequate measures of states' high school completion rates, and (3. potentially inadequate measures of minimum wage rates. Overcoming each of these limitations, we analyze the impact of changes in…

  12. High rate fabrication of compression molded components

    DOEpatents

    Matsen, Marc R.; Negley, Mark A.; Dykstra, William C.; Smith, Glen L.; Miller, Robert J.

    2016-04-19

    A method for fabricating a thermoplastic composite component comprises inductively heating a thermoplastic pre-form with a first induction coil by inducing current to flow in susceptor wires disposed throughout the pre-form, inductively heating smart susceptors in a molding tool to a leveling temperature with a second induction coil by applying a high-strength magnetic field having a magnetic flux that passes through surfaces of the smart susceptors, shaping the magnetic flux that passes through surfaces of the smart susceptors to flow substantially parallel to a molding surface of the smart susceptors, placing the heated pre-form between the heated smart susceptors; and applying molding pressure to the pre-form to form the composite component.

  13. Dose rate in brachytherapy using after-loading machine: pulsed or high-dose rate?

    PubMed

    Hannoun-Lévi, J-M; Peiffert, D

    2014-10-01

    Since February 2014, it is no longer possible to use low-dose rate 192 iridium wires due to the end of industrial production of IRF1 and IRF2 sources. The Brachytherapy Group of the French society of radiation oncology (GC-SFRO) has recommended switching from iridium wires to after-loading machines. Two types of after-loading machines are currently available, based on the dose rate used: pulsed-dose rate or high-dose rate. In this article, we propose a comparative analysis between pulsed-dose rate and high-dose rate brachytherapy, based on biological, technological, organizational and financial considerations. PMID:25195117

  14. Health costs of reproduction are minimal despite high fertility, mortality and subsistence lifestyle

    PubMed Central

    Gurven, Michael; Costa, Megan; Ben Trumble; Stieglitz, Jonathan; Beheim, Bret; Eid Rodriguez, Daniel; Hooper, Paul L.; Kaplan, Hillard

    2016-01-01

    Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n =  592 aged 15–44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 years. Higher parity and faster reproductive pace are associated with lower nutritional status (indicated by weight, body mass index, body fat) in a cross-section, but longitudinal analyses show improvements in women’s nutritional status with age. Biomarkers of immune function and anemia vary little with parity or pace of reproduction. Our findings demonstrate that even under energy-limited and infectious conditions, women are buffered from the potential depleting effects of rapid reproduction and compound offspring dependency characteristic of human life histories. PMID:27436412

  15. Health costs of reproduction are minimal despite high fertility, mortality and subsistence lifestyle.

    PubMed

    Gurven, Michael; Costa, Megan; Ben Trumble; Stieglitz, Jonathan; Beheim, Bret; Eid Rodriguez, Daniel; Hooper, Paul L; Kaplan, Hillard

    2016-01-01

    Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n =  592 aged 15-44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 years. Higher parity and faster reproductive pace are associated with lower nutritional status (indicated by weight, body mass index, body fat) in a cross-section, but longitudinal analyses show improvements in women's nutritional status with age. Biomarkers of immune function and anemia vary little with parity or pace of reproduction. Our findings demonstrate that even under energy-limited and infectious conditions, women are buffered from the potential depleting effects of rapid reproduction and compound offspring dependency characteristic of human life histories. PMID:27436412

  16. High data rate optical transceiver terminal

    NASA Technical Reports Server (NTRS)

    Clarke, E. S.

    1973-01-01

    The objectives of this study were: (1) to design a 400 Mbps optical transceiver terminal to operate from a high-altitude balloon-borne platform in order to permit the quantitative evaluation of a space-qualifiable optical communications system design, (2) to design an atmospheric propagation experiment to operate in conjunction with the terminal to measure the degrading effects of the atmosphere on the links, and (3) to design typical optical communications experiments for space-borne laboratories in the 1980-1990 time frame. As a result of the study, a transceiver package has been configured for demonstration flights during late 1974. The transceiver contains a 400 Mbps transmitter, a 400 Mbps receiver, and acquisition and tracking receivers. The transmitter is a Nd:YAG, 200 Mhz, mode-locked, CW, diode-pumped laser operating at 1.06 um requiring 50 mW for 6 db margin. It will be designed to implement Pulse Quaternary Modulation (PQM). The 400 Mbps receiver utilizes a Dynamic Crossed-Field Photomultiplier (DCFP) detector. The acquisition receiver is a Quadrant Photomultiplier Tube (QPMT) and receives a 400 Mbps signal chopped at 0.1 Mhz.

  17. High HIV Rates for Gay Men in Some Southern Cities

    MedlinePlus

    ... news/fullstory_158914.html High HIV Rates for Gay Men in Some Southern Cities In Jackson, Miss., ... 2016 (HealthDay News) -- Rates of HIV infection among gay and bisexual men are approaching 30 percent to ...

  18. Evolution of male age-specific reproduction under differential risks and causes of death: males pay the cost of high female fitness.

    PubMed

    Chen, H-Y; Spagopoulou, F; Maklakov, A A

    2016-04-01

    Classic theories of ageing evolution predict that increased extrinsic mortality due to an environmental hazard selects for increased early reproduction, rapid ageing and short intrinsic lifespan. Conversely, emerging theory maintains that when ageing increases susceptibility to an environmental hazard, increased mortality due to this hazard can select against ageing in physiological condition and prolong intrinsic lifespan. However, evolution of slow ageing under high-condition-dependent mortality is expected to result from reallocation of resources to different traits and such reallocation may be hampered by sex-specific trade-offs. Because same life-history trait values often have different fitness consequences in males and females, sexually antagonistic selection can preserve genetic variance for lifespan and ageing. We previously showed that increased condition-dependent mortality caused by heat shock leads to evolution of long-life, decelerated late-life mortality in both sexes and increased female fecundity in the nematode, Caenorhabditis remanei. Here, we used these cryopreserved lines to show that males evolving under heat shock suffered from reduced early-life and net reproduction, while mortality rate had no effect. Our results suggest that heat-shock resistance and associated long-life trade-off with male, but not female, reproduction and therefore sexually antagonistic selection contributes to maintenance of genetic variation for lifespan and fitness in this population. PMID:26801472

  19. Reproductive toxicity in rats with crystal nephropathy following high doses of oral melamine or cyanuric acid.

    PubMed

    Stine, Cynthia B; Reimschuessel, Renate; Keltner, Zachary; Nochetto, Cristina B; Black, Thomas; Olejnik, Nicholas; Scott, Michael; Bandele, Omari; Nemser, Sarah M; Tkachenko, Andriy; Evans, Eric R; Crosby, Tina C; Ceric, Olgica; Ferguson, Martine; Yakes, Betsy J; Sprando, Robert

    2014-06-01

    The industrial chemical melamine was used in 2007 and 2008 to raise the apparent protein content in pet feed and watered down milk, respectively. Because humans may be exposed to melamine via several different routes into the human diet as well as deliberate contamination, this study was designed to characterize the effect of high dose melamine or cyanuric acid oral exposure on the pregnant animal and developing fetus, including placental transfer. Clear rectangular crystals formed following a single triazine exposure which is a different morphology from the golden spherulites caused by combined exposure or the calculi formed when melamine combines with endogenous uric acid. Crystal nephropathy, regardless of cause, induces renal failure which in turn has reproductive sequelae. Specifically, melamine alone-treated dams had increased numbers of early and late fetal deaths compared to controls or cyanuric acid-treated dams. As melamine was found in the amniotic fluid, this study confirms transfer of melamine from mammalian mother to fetus and our study provides evidence that cyanuric acid also appears in the amniotic fluid if mothers are exposed to high doses. PMID:24582682

  20. Pathogenicity comparison between highly pathogenic and NADC30-like porcine reproductive and respiratory syndrome virus.

    PubMed

    Sun, Zhe; Wang, Juan; Bai, Xiaofei; Ji, Guobiao; Yan, He; Li, Yingying; Wang, Yuzhou; Tan, Feifei; Xiao, Yan; Li, Xiangdong; Tian, Kegong

    2016-08-01

    The pathogenicity of HNjz15, an NADC30-like strain of porcine reproductive and respiratory syndrome virus (PRRSV), was investigated and compared to that of a highly pathogenic PRRSV JAX1 strain. Six-week-old pigs infected with each virus showed typical clinical symptoms, including high fever and respiratory disorders. Pigs infected with JXA1 had more-severe clinical manifestations than pigs infected with HNjz15. HNjz15 replicated in vivo with kinetics similar to those of JXA1 but induced a lower level of PRRSV-specific antibody at the beginning of virus infection. Histopathologically, JXA1 infection led to more-severe lung lesions and broader organ tropism than HNjz15 did. Different from what was observed with the previously reported NADC30-like PRRSV JL580 strain, all HNjz15-infected pigs survived until the end of the study. All of these results indicated that NADC30-like PRRSV HNjz15 is virulent to pigs but is less pathogenic than the JXA1 and JL580 PRRSV strains. PMID:27151278

  1. Exposure to Hypoxia at High Altitude (5380 m) for 1 Year Induces Reversible Effects on Semen Quality and Serum Reproductive Hormone Levels in Young Male Adults.

    PubMed

    He, Jiang; Cui, Jianhua; Wang, Rui; Gao, Liang; Gao, Xiaokang; Yang, Liu; Zhang, Qiong; Cao, Jinjun; Yu, Wuzhong

    2015-09-01

    This study investigated the effect of hypoxia at high altitude on the semen quality and the serum reproductive hormone levels in male adults. A total of 52 male soldiers were enrolled in this cohort study. They were exposed to hypoxia at high altitude (5380 m) for 12 months when undergoing a service. After exposure, they were followed up for 6 months. The samples of semen and peripheral blood were collected at 1 month before exposure (M0), 6 months of exposure (M6), 12 months of exposure (M12), and 6 months after exposure (M18). The semen quality was assessed with computer-assisted analysis system, and the serum levels of reproductive hormones, including prolactin (PRL), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and testosterone were analyzed by ELISA. Compared with those at M0, total sperm count, sperm density, motility, survival rate, and serum levels of LH, PRL and testosterone were significantly decreased, whereas the liquefaction time was significantly prolonged and serum FSH level was significantly increased at M6 (p<0.05). At M12, total sperm count and sperm density increased, whereas sperm motility, survival rate, and the liquefaction time further decreased. Sperm velocities, progression ratios, and lateral head displacements were also decreased. Serum FSH level decreased while serum LH, PRL, and testosterone levels increased. Compared with those at M6, the changes in these detected parameters of semen and hormone at M12 were significant (p<0.05). At M18, all these detected parameters except testosterone level returned to levels comparable to those before exposure. In conclusion, hypoxia at high altitude causes adverse effects on semen quality and reproductive hormones, and these effects are reversible. PMID:26288097

  2. High-Rate Strong-Signal Quantum Cryptography

    NASA Technical Reports Server (NTRS)

    Yuen, Horace P.

    1996-01-01

    Several quantum cryptosystems utilizing different kinds of nonclassical lights, which can accommodate high intensity fields and high data rate, are described. However, they are all sensitive to loss and both the high rate and the strong-signal character rapidly disappear. A squeezed light homodyne detection scheme is proposed which, with present-day technology, leads to more than two orders of magnitude data rate improvement over other current experimental systems for moderate loss.

  3. HIV prevalence among high school learners - opportunities for schools-based HIV testing programmes and sexual reproductive health services

    PubMed Central

    2012-01-01

    Background Young girls in sub Saharan Africa are reported to have higher rates of human immunodeficiency virus (HIV) infection compared to boys in the same age group. Knowledge of HIV status amongst high schools learners provides an important gateway to prevention and treatment services. This study aimed at determining the HIV prevalence and explored the feasibility of HIV testing among high school learners. Methods Between September 2010 and February 2011, a linked, anonymous cross-sectional survey was conducted in two public sector high schools in the rural KwaZulu-Natal midlands. Following written informed consent, dried blood spot samples (DBS) were collected and tested for HIV. The overall and age-specific HIV prevalence were compared with select demographic variables. Results The HIV prevalence in learners aged 12 to 25 in school A was 4.7% (95% CI 2.8-6.5) compared to 2.5% (95% CI 1.6-3.5) in school B, (p = 0.04). Whilst the HIV prevalence was similar for boys at 1.3% (95% CI 0-2.8) in school A and 1.7% (95% CI 0.5-2.8) in school B, the prevalence in girls was consistently higher and was 7.7% (95% CI 4.5-10.9) in school A and 3.2% (95% CI 1.8-4.6) in school B. The age-specific HIV prevalence in girls increased 1.5 to 2 fold for each two year age category, while for boys the prevalence was stable across all age groups. Conclusions The high HIV prevalence in female learners underscores the importance of sexual reproductive health and schools-based HIV testing programs as an important gateway to prevention and treatment services. PMID:22439635

  4. Temperature-driven flower longevity in a high-alpine species of Oxalis influences reproductive assurance.

    PubMed

    Arroyo, Mary T K; Dudley, Leah S; Jespersen, Gus; Pacheco, Diego A; Cavieres, Lohengrin A

    2013-12-01

    How high-alpine plants confront stochastic conditions for animal pollination is a critical question. We investigated the effect of temperature on potential flower longevity (FL) measured in pollinator-excluded flowers and actual FL measured in pollinated flowers in self-incompatible Oxalis compacta and evaluated if plastically prolonged potential FL can ameliorate slow pollination under cool conditions. Pollinator-excluded and hand-pollinated flowers were experimentally warmed with open-top chambers (OTCs) on a site at 3470 m above sea level (asl). Flower-specific temperatures, and pollinator-excluded and open-pollination flower life-spans were measured at six alpine sites between 3100 and 3470 m asl. Fruit set was analyzed in relation to inferred pollination time. Warming reduced potential FL. Variable thermal conditions across the alpine landscape predicted potential and actual FL; flower senescence was pollination-regulated. Actual FL and potential FL were coupled. Prolonged potential FL generally increased fruit set under cooler conditions. Plastic responses permit virgin flowers of O. compacta to remain open longer under cooler temperatures, thereby ameliorating slow pollination, and to close earlier when pollination tends to be faster under warmer conditions. Plastic potential FL provides adaptive advantages in the cold, thermally variable alpine habitat, and has important implications for reproductive success in alpine plants in a warming world. PMID:23952472

  5. Immune responses in piglets infected with highly pathogenic porcine reproductive and respiratory syndrome virus.

    PubMed

    Wang, Gang; Song, Tengfei; Yu, Ying; Liu, Yonggang; Shi, Wenda; Wang, Shujie; Rong, Fulong; Dong, Jianguo; Liu, He; Cai, Xuehui; Zhou, En-Min

    2011-08-15

    Porcine reproductive and respiratory syndrome virus (PRRSV) infection compromises the host's innate and adaptive immunity. The aim of this study was to investigate the immune responses of piglets infected with highly pathogenic (HP) PRRSV (HuN4 strain) with or without the immunization with CH-1R attenuated PRRSV vaccine. The response was evaluated for the clinical signs, pathological changes and virus load in immune organs, antibody responses and levels of serum IFN-γ, IL-4 and IL-10. The result showed that in comparison with the piglets received the immunization, the piglets infected with HP-PRRSV alone had the thymus atrophy, decreased serum levels of IL-4 and increased serum levels of IL-10 and INF-γ. These results suggest that elevated IL-10 levels at the early stage of the infection may enhance virus survival and delay the induction of protective immunity, while increased levels of IL-4 induce the effective immune responses and increase the animals' health status. PMID:21612828

  6. Toward the definition of a carbon budget model: seasonal variation and temperature effect on respiration rate of vegetative and reproductive organs of pistachio trees (Pistacia vera).

    PubMed

    Marra, Francesco P; Barone, Ettore; La Mantia, Michele; Caruso, Tiziano

    2009-09-01

    This study, as a preliminary step toward the definition of a carbon budget model for pistachio trees (Pistacia vera L.), aimed at estimating and evaluating the dynamics of respiration of vegetative and reproductive organs of pistachio tree. Trials were performed in 2005 in a commercial orchard located in Sicily (370 m a.s.l.) on five bearing 20-year-old pistachio trees of cv. Bianca grafted onto Pistachio terebinthus L. Growth analyses and respiration measurements were done on vegetative (leaf) and reproductive (infructescence) organs during the entire growing season (April-September) at biweekly intervals. Results suggested that the respiration rates of pistachio reproductive and vegetative organs were related to their developmental stage. Both for leaf and for infructescence, the highest values were observed during the earlier stages of growth corresponding to the phases of most intense organ growth. The sensitivity of respiration activity to temperature changes, measured by Q(10), showed an increase throughout the transition from immature to mature leaves, as well as during fruit development. The data collected were also used to estimate the seasonal carbon loss by respiration activity for a single leaf and a single infructescence. The amount of carbon lost by respiration was affected by short-term temperature patterns, organ developmental stage and tissue function. PMID:19661135

  7. High-resolution laser radar for 3D imaging in artwork cataloging, reproduction, and restoration

    NASA Astrophysics Data System (ADS)

    Ricci, Roberto; Fantoni, Roberta; Ferri de Collibus, Mario; Fornetti, Giorgio G.; Guarneri, Massimiliano; Poggi, Claudio

    2003-10-01

    A high resolution Amplitude Modulated Laser Radar (AM-LR) sensor has recently been developed, aimed at accurately reconstructing 3D digital models of real targets, either single objects or complex scenes. The sensor sounding beam can be swept linearly across the object or circularly around it, by placing the object on a controlled rotating platform, enabling to obtain respectively linear and cylindrical range maps. Both amplitude and phase shift of the modulating wave of back-scattered light are collected and processed, providing respectively a shade-free, high resolution, photographic-like picture and accurate range data in the form of a range image. The resolution of range measurements depends mainly on the laser modulation frequency, provided that the power of the backscattered light reaching the detector is at least a few nW (current best performances are ~100 μm). The complete object surface can be reconstructed from the sampled points by using specifically developed software tools. The system has been successfully applied to scan different types of real surfaces (stone, wood, alloys, bones), with relevant applications in different fields, ranging from industrial machining to medical diagnostics, to vision in hostile environments. Examples of artwork reconstructed models (pottery, marble statues) are presented and the relevance of this technology for reverse engineering applied to cultural heritage conservation and restoration are discussed. Final 3D models can be passed to numeric control machines for rapid-prototyping, exported in standard formats for CAD/CAM purposes and made available on the Internet by adopting a virtual museum paradigm, thus possibly enabling specialists to perform remote inspections on high resolution digital reproductions of hardly accessible masterpieces.

  8. Biodistribution, with high uptake by the reproductive tract, of an intraperitoneally infused radiohalogenated steroidal estrogen-receptor ligand.

    PubMed

    Holt, J A; Artwohl, J E; Mercer, L J; Pryde, P G

    1991-03-01

    We infused [123I]16 alpha-(123I)-iodo-estradiol ([123I]E2) intraperitoneally (i.p.) into swine to study its biodistribution and to explore the i.p. use of radiohalogenated steroid estrogen-receptor (ER) ligands as a potential option for diagnosing and treating intra-abdominal, retroperitoneal, and distant sites of advanced ER-rich malignancies. Fifty to 80% of the radiolabel was absorbed from the peritoneal cavity within 30 minutes, and 30 to 50% of the infused radiolabel was excreted in the urine within 2 hr. The rate of biliary clearance was maximal within 25 minutes. At 3 hr, the ER-rich reproductive tract had greater than 63 times the concentration of radiolabel in blood; the former was blocked by non-labeled competitors for ER. Uptake by non-ER-rich tissues, compared to blood, ranged from 0.7:1 (heart and lungs) to 16:1 (spleen); the omentum, however, exhibited a concentration as high as 64:1, which was not blocked by non-labeled ER ligands. Uptake by ER-rich target tissue remained high when charcoal was used to prevent reabsorption of radiolabel from the digestive tract after its biliary excretion, and when the products of biliary excretion were removed by catheterization of the common bile duct. Neither charcoal nor exteriorization of bile appeared to affect urinary clearance of the radiolabel over the time course of the experiments. Taken together with the recent development of syntheses that yield radiohalogenated sex steroid receptor ligands of high specific activity, our findings are encouraging for the potential application of radiolabeled ligands as i.p. administered pharmaceuticals. The advantage of the i.p. route is that it provides direct uptake of the pharmaceutical by free-floating clusters and individual cancer cells in ascitic fluid, as well as delivery via the circulation to vascularized intra- and/or extraperitoneal metastases. PMID:1995542

  9. Direct costs and benefits of multiple mating: Are high female mating rates due to ejaculate replenishment?

    PubMed

    Worthington, Amy M; Kelly, Clint D

    2016-03-01

    Females often mate more than is necessary to ensure reproductive success even when they incur significant costs from doing so. Direct benefits are hypothesized to be the driving force of high female mating rates, yet species in which females only receive an ejaculate from their mate still realize increased fitness from multiple mating. Using the Texas field cricket, Gryllus texensis, we experimentally test the hypothesis that multiple mating via monandry or polyandry increases female fitness by replenishing ejaculates, thereby allowing females to produce more offspring for a longer period of time. We found that higher rates of female mating significantly increased lifetime fecundity and oviposition independent of whether females mated with one or two males. Further, although interactions with males significantly increased rates of injury or death, females that replenished ejaculates experienced an increased rate and duration of oviposition, demonstrating that the immediate benefits of multiple mating may greatly outweigh the long-term costs that mating poses to female condition and survival. We suggest that ejaculate replenishment is a driving factor of high mating rates in females that do not receive external direct benefits from mating and that a comparative study across taxa will provide additional insight into the role that ejaculate size plays in the evolution of female mating rates. PMID:26772782

  10. East Los High: Transmedia Edutainment to Promote the Sexual and Reproductive Health of Young Latina/o Americans

    PubMed Central

    Singhal, Arvind

    2016-01-01

    Latina/o Americans are at high risk for sexually transmitted infections and adolescent pregnancies. Needed urgently are innovative health promotion approaches that are engaging and culturally sensitive. East Los High is a transmedia edutainment program aimed at young Latina/o Americans. It embeds educational messages in entertainment narratives across digital platforms to promote sexual and reproductive health. We employed online analytics tracking (2013–2014), an online viewer survey (2013), and a laboratory experiment (El Paso, TX, 2014) for season 1 program evaluation. We found that East Los High had a wide audience reach, strong viewer engagement, and a positive cognitive, emotional, and social impact on sexual and reproductive health communication and education. Culturally sensitive transmedia edutainment programs are a promising health promotion strategy for minority populations and warrant further investigation. PMID:27077336

  11. East Los High: Transmedia Edutainment to Promote the Sexual and Reproductive Health of Young Latina/o Americans.

    PubMed

    Wang, Hua; Singhal, Arvind

    2016-06-01

    Latina/o Americans are at high risk for sexually transmitted infections and adolescent pregnancies. Needed urgently are innovative health promotion approaches that are engaging and culturally sensitive. East Los High is a transmedia edutainment program aimed at young Latina/o Americans. It embeds educational messages in entertainment narratives across digital platforms to promote sexual and reproductive health. We employed online analytics tracking (2013-2014), an online viewer survey (2013), and a laboratory experiment (El Paso, TX, 2014) for season 1 program evaluation. We found that East Los High had a wide audience reach, strong viewer engagement, and a positive cognitive, emotional, and social impact on sexual and reproductive health communication and education. Culturally sensitive transmedia edutainment programs are a promising health promotion strategy for minority populations and warrant further investigation. PMID:27077336

  12. Patterns of male reproductive success in a highly promiscuous whale species: the endangered North Atlantic right whale.

    PubMed

    Frasier, T R; Hamilton, P K; Brown, M W; Conger, L A; Knowlton, A R; Marx, M K; Slay, C K; Kraus, S D; White, B N

    2007-12-01

    Parentage analyses of baleen whales are rare, and although mating systems have been hypothesized for some species, little data on realized male reproductive success are available and the patterns of male reproductive success have remained elusive for most species. Here we combine over 20 years of photo-identification data with high-resolution genetic data for the majority of individual North Atlantic right whales to assess paternity in this endangered species. There was significant skew in male reproductive success compared to what would be expected if mating was random (P < 0.001). The difference was due to an excess of males assigned zero paternities, a deficiency of males assigned one paternity, and an excess of males assigned as fathers for multiple calves. The variance in male reproductive success was high relative to other aquatically mating marine mammals, but was low relative to mammals where the mating system is based on resource- and/or mate-defence polygyny. These results are consistent with previous data suggesting that the right whale mating system represents one of the most intense examples of sperm competition in mammals, but that sperm competition on its own does not allow for the same degree of polygyny as systems where males can control access to resources and/or mates. The age distribution of assigned fathers was significantly biased towards older males (P < 0.05), with males not obtaining their first paternity until approximately 15 years of age, which is almost twice the average age of first fertilization in females (8 years), suggesting that mate competition is preventing younger males from reproducing. The uneven distribution of paternities results in a lower effective population size in this species that already has one of the lowest reported levels of genetic diversity, which may further inhibit reproductive success through mate incompatibility of genetically similar individuals. PMID:17971086

  13. Metridia pacifica in Dabob Bay, Washington: The diatom effect and the discrepancy between high abundance and low egg production rates

    NASA Astrophysics Data System (ADS)

    Halsband-Lenk, Claudia

    2005-11-01

    Information on life cycle strategies and reproductive parameters of Metridia pacifica is scarce, despite its importance in the zooplankton of the subarctic Pacific. In many regions it occurs in high abundance, but reproductive rates, when reported, are usually low. This discrepancy was studied in Dabob Bay, Washington, USA, in the context of an investigation of the effect of diatom blooms on the reproductive success of copepod grazers. In situ egg production rates of M. pacifica were measured in spring and mid-summer with standard methods (multi-wells) and a new incubation chamber (spawning towers) that separates the spawning female from its eggs and allows the eggs to develop undisturbed. Many females did not produce eggs, possibly due to a high fraction of immature individuals. Egg production rates were variable, but clutch sizes were higher in spawning towers, and estimates of female egg cannibalism revealed that females consume many eggs shortly after their release. Thus, a separation of females and eggs is mandatory for accurate measurements of M. pacifica egg production rates. The maximum clutch sizes recorded in our study were comparable to measurements for other calanoids. However, unviable eggs were a large fraction of those spawned, independent of incubation method, especially in late winter and early spring. In order to assess whether the diatom effect may be responsible for low viability of embryos and nauplii, we also measured in situ grazing. Adult females were omnivorous, but they ingested some diatoms that rank among the strongest anti-mitotic toxin producers known so far. Although M. pacifica’s vertical migration behavior suggests opportunistic feeding on abundant food during their short stay in the phytoplankton-rich surface, they often ignored the food items that contributed most to microplankton carbon concentrations. Thus, their feeding strategy remains ambiguous. Due to severe reproductive failure early in the season, recruitment was

  14. High-shear-rate capillary viscometer for inkjet inks

    NASA Astrophysics Data System (ADS)

    Wang, Xi; Carr, Wallace W.; Bucknall, David G.; Morris, Jeffrey F.

    2010-06-01

    A capillary viscometer developed to measure the apparent shear viscosity of inkjet inks at high apparent shear rates encountered during inkjet printing is described. By using the Weissenberg-Rabinowitsch equation, true shear viscosity versus true shear rate is obtained. The device is comprised of a constant-flow generator, a static pressure monitoring device, a high precision submillimeter capillary die, and a high stiffness flow path. The system, which is calibrated using standard Newtonian low-viscosity silicone oil, can be easily operated and maintained. Results for measurement of the shear-rate-dependent viscosity of carbon-black pigmented water-based inkjet inks at shear rates up to 2×105 s-1 are discussed. The Cross model was found to closely fit the experimental data. Inkjet ink samples with similar low-shear-rate viscosities exhibited significantly different shear viscosities at high shear rates depending on particle loading.

  15. High-shear-rate capillary viscometer for inkjet inks

    SciTech Connect

    Wang Xi; Carr, Wallace W.; Bucknall, David G.; Morris, Jeffrey F.

    2010-06-15

    A capillary viscometer developed to measure the apparent shear viscosity of inkjet inks at high apparent shear rates encountered during inkjet printing is described. By using the Weissenberg-Rabinowitsch equation, true shear viscosity versus true shear rate is obtained. The device is comprised of a constant-flow generator, a static pressure monitoring device, a high precision submillimeter capillary die, and a high stiffness flow path. The system, which is calibrated using standard Newtonian low-viscosity silicone oil, can be easily operated and maintained. Results for measurement of the shear-rate-dependent viscosity of carbon-black pigmented water-based inkjet inks at shear rates up to 2x10{sup 5} s{sup -1} are discussed. The Cross model was found to closely fit the experimental data. Inkjet ink samples with similar low-shear-rate viscosities exhibited significantly different shear viscosities at high shear rates depending on particle loading.

  16. High Graduate Unemployment Rate and Taiwanese Undergraduate Education

    ERIC Educational Resources Information Center

    Wu, Chih-Chun

    2011-01-01

    An expansion in higher education in combination with the recent global economic recession has resulted in a high college graduate unemployment rate in Taiwan. This study investigates how the high unemployment rate and financial constraints caused by economic cutbacks have shaped undergraduates' class choices, job needs, and future income…

  17. High School Graduation Rates: Alternative Methods and Implications

    ERIC Educational Resources Information Center

    Miao, Jing; Haney, Walt

    2004-01-01

    The No Child Left Behind Act has brought great attention to the high school graduation rate as one of the mandatory accountability measures for public school systems. However, there is no consensus on how to calculate the high school graduation rate given the lack of longitudinal databases that track individual students. This study reviews…

  18. HIGH-RATE DISINFECTION TECHNIQUES FOR COMBIND SEWER OVERFLOW

    EPA Science Inventory

    This paper presents high-rate disinfection technologies for combined sewer overflow (CSO). The high-rate disinfection technologies of interest are: chlorination/dechlorination, ultraviolet light irradiation (UV), chlorine dioxide (ClO2 ), ozone (O3), peracetic acid (CH3COOOH )...

  19. Continuous operation of high bit rate quantum key distribution

    NASA Astrophysics Data System (ADS)

    Dixon, A. R.; Yuan, Z. L.; Dynes, J. F.; Sharpe, A. W.; Shields, A. J.

    2010-04-01

    We demonstrate a quantum key distribution with a secure bit rate exceeding 1 Mbit/s over 50 km fiber averaged over a continuous 36 h period. Continuous operation of high bit rates is achieved using feedback systems to control path length difference and polarization in the interferometer and the timing of the detection windows. High bit rates and continuous operation allows finite key size effects to be strongly reduced, achieving a key extraction efficiency of 96% compared to keys of infinite lengths.

  20. CONTROL OF REPRODUCTION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Control of reproduction is important for seed stock production, selective breeding, growth rate, feed efficiency, meat quality, and biosecurity. These needs to control reproduction differ among cultivars and even segments of the same industry. No matter the impetus for aquaculturists to want to alte...

  1. Authoritative school climate and high school dropout rates.

    PubMed

    Jia, Yuane; Konold, Timothy R; Cornell, Dewey

    2016-06-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high school dropout rates. Analyses controlled for school demographics of school enrollment size, percentage of low-income students, percentage of minority students, and urbanicity. Consistent with authoritative school climate theory, moderation analyses found that when students perceive their teachers as supportive, high academic expectations are associated with lower dropout rates. (PsycINFO Database Record PMID:26641957

  2. HIGH-RATE FORMABILITY OF HIGH-STRENGTH ALUMINUM ALLOYS: A STUDY ON OBJECTIVITY OF MEASURED STRAIN AND STRAIN RATE

    SciTech Connect

    Upadhyay, Piyush; Rohatgi, Aashish; Stephens, Elizabeth V.; Davies, Richard W.; Catalini, David

    2015-02-18

    Al alloy AA7075 sheets were deformed at room temperature at strain-rates exceeding 1000 /s using the electrohydraulic forming (EHF) technique. A method that combines high speed imaging and digital image correlation technique, developed at Pacific Northwest National Laboratory, is used to investigate high strain rate deformation behavior of AA7075. For strain-rate sensitive materials, the ability to accurately model their high-rate deformation behavior is dependent upon the ability to accurately quantify the strain-rate that the material is subjected to. This work investigates the objectivity of software-calculated strain and strain rate by varying different parameters within commonly used commercially available digital image correlation software. Except for very close to the time of crack opening the calculated strain and strain rates are very consistent and independent of the adjustable parameters of the software.

  3. High Prevalence of Vitamin D Deficiency in Infertile Women Referring for Assisted Reproduction.

    PubMed

    Pagliardini, Luca; Vigano', Paola; Molgora, Michela; Persico, Paola; Salonia, Andrea; Vailati, Simona Helda; Paffoni, Alessio; Somigliana, Edgardo; Papaleo, Enrico; Candiani, Massimo

    2015-12-01

    A comprehensive analysis of the vitamin D status of infertile women is the first step in understanding hypovitaminosis impact on reproductive potential. We sought to determine vitamin D profiles of women attending an infertility center and to investigate non-dietary determinants of vitamin D status in this population. In this cross-sectional analysis, a cohort of 1072 women (mean age ± standard deviation 36.3 ± 4.4 years) attending an academic infertility center was used to examine serum 25-hydroxy-vitamin D (25(OH)D) levels in relation to demographic characteristics, seasons and general health risk factors. Both unadjusted and adjusted levels of serum 25(OH)D were examined. Median 25(OH)D concentration was below 30 ng/mL for 89% of the entire year. Over the whole year, 6.5% of patients had 25(OH)D levels ≤10 ng/mL, 40.1% ≤20 ng/mL, and 77.4% ≤30 ng/mL. Global solar radiation was weakly correlated with 25(OH)D levels. At multivariable analysis, 25(OH)D levels were inversely associated with BMI; conversely, 25(OH)D levels were positively associated with height and endometriosis history. Serum 25(OH)D levels are highly deficient in women seeking medical help for couple's infertility. Levels are significantly associated with body composition, seasonal modifications and causes of infertility. Importantly, this deficiency status may last during pregnancy with more severe consequences. PMID:26633484

  4. Climate Warming May Threaten Reproductive Diapause of a Highly Eusocial Bee.

    PubMed

    Dos Santos, Charles Fernando; Acosta, André Luis; Nunes-Silva, Patrícia; Saraiva, Antonio Mauro; Blochtein, Betina

    2015-08-01

    Climate changes are predicted to affect the diapause of many insect species around the world adversely. In this context, bees are of interest due to their pollination services. In southern Brazil, the highly eusocial bee species Plebeia droryana (Friese) (Hymenoptera: Apidae: Meliponini) exhibits reproductive diapause in response to the region's rigorous winters. That diapause is characterized by a temporary interruption in brood cell construction by nurse bees and egg-laying by the queen, regardless of other internal tasks underway in the nests. In this study, we evaluated whether P. droryana enter diapause under experimental conditions. P. droryana colonies were kept in a germination chamber, and the temperature was progressively reduced from 20°C over a period of a few weeks until diapause was detected. Additionally, we also estimated the environmental conditions in the actual geographic range occupied by P. droryana and modeled it for predicted changes in climate up to the year 2080. Our findings indicate that P. droryana enter diapause between 10 and 8°C. We also found that the current minimum winter temperature (10.1°C, median) in the distributional range of P. droryana will probably rise (13.4°C, median). Thus, if our experimental data are somewhat accurate, ∼36% of the southern Brazilian P. droryana population may be active during the expected milder winter months in 2080. In this scenario, there may be a larger demand for pollen and nectar for that bee species. Greater conservation efforts will be required to preserve P. droryana populations and keep them viable in the coming decades. PMID:26314063

  5. High Prevalence of Vitamin D Deficiency in Infertile Women Referring for Assisted Reproduction

    PubMed Central

    Pagliardini, Luca; Vigano’, Paola; Molgora, Michela; Persico, Paola; Salonia, Andrea; Vailati, Simona Helda; Paffoni, Alessio; Somigliana, Edgardo; Papaleo, Enrico; Candiani, Massimo

    2015-01-01

    A comprehensive analysis of the vitamin D status of infertile women is the first step in understanding hypovitaminosis impact on reproductive potential. We sought to determine vitamin D profiles of women attending an infertility center and to investigate non-dietary determinants of vitamin D status in this population. In this cross-sectional analysis, a cohort of 1072 women (mean age ± standard deviation 36.3 ± 4.4 years) attending an academic infertility center was used to examine serum 25-hydroxy-vitamin D (25(OH)D) levels in relation to demographic characteristics, seasons and general health risk factors. Both unadjusted and adjusted levels of serum 25(OH)D were examined. Median 25(OH)D concentration was below 30 ng/mL for 89% of the entire year. Over the whole year, 6.5% of patients had 25(OH)D levels ≤10 ng/mL, 40.1% ≤20 ng/mL, and 77.4% ≤30 ng/mL. Global solar radiation was weakly correlated with 25(OH)D levels. At multivariable analysis, 25(OH)D levels were inversely associated with BMI; conversely, 25(OH)D levels were positively associated with height and endometriosis history. Serum 25(OH)D levels are highly deficient in women seeking medical help for couple’s infertility. Levels are significantly associated with body composition, seasonal modifications and causes of infertility. Importantly, this deficiency status may last during pregnancy with more severe consequences. PMID:26633484

  6. Miniature high stability high temperature space rated blackbody radiance source

    NASA Technical Reports Server (NTRS)

    Jones, J. A.; Beswick, A. G.

    1987-01-01

    This paper presents the design and test performance of a conical cavity type blackbody radiance source that will meet the requirements of the Halogen Occultation Experiment on the NASA Upper Atmospheric Research Satellite program. The thrust of this design effort was to minimize the heat losses, in order to keep the power usage under 7.5 watts, and to minimize the amount of silica in the materials. Silica in the presence of the platinum heater winding used in this design would cause the platinum to erode, changing the operating temperature set-point. The design required the development of fabrication techniques which would provide very small, close tolerance parts from extremely difficult-to-machine materials. Also, a space rated ceramic core and unique, low thermal conductance, ceramic-to-metal joint was developed, tested and incorporated in this design. The completed flight qualification hardware has undergone performance, environmental and life testing. The design configuration and test results are discussed in detail.

  7. Plants and Photosynthesis: Level III, Unit 3, Lesson 1; The Human Digestive System: Lesson 2; Functions of the Blood: Lesson 3; Human Circulation and Respiration: Lesson 4; Reproduction of a Single Cell: Lesson 5; Reproduction by Male and Female Cells: Lesson 6; The Human Reproductive System: Lesson 7; Genetics and Heredity: Lesson 8; The Nervous System: Lesson 9; The Glandular System: Lesson 10. Advanced General Education Program. A High School Self-Study Program.

    ERIC Educational Resources Information Center

    Manpower Administration (DOL), Washington, DC. Job Corps.

    This self-study program for the high-school level contains lessons in the following subjects: Plants and Photosynthesis; The Human Digestive System; Functions of the Blood; Human Circulation and Respiration; Reproduction of a Single Cell; Reproduction by Male and Female Cells; The Human Reproductive System; Genetics and Heredity; The Nervous…

  8. High data-rate atom interferometer for measuring acceleration

    SciTech Connect

    McGuinness, Hayden J.; Rakholia, Akash V.; Biedermann, Grant W.

    2012-01-02

    We demonstrate a high data-rate light-pulse atom interferometer for measuring acceleration. The device is optimized to operate at rates between 50 Hz to 330 Hz with sensitivities of 0.57{mu}g/{radical}(Hz) to 36.7{mu}g/{radical}(Hz), respectively. Our method offers a dramatic increase in data rate and demonstrates a path to applications in highly dynamic environments. The performance of the device can largely be attributed to the high recapture efficiency of atoms from one interferometer measurement cycle to another.

  9. Quantum data locking for high-rate private communication

    NASA Astrophysics Data System (ADS)

    Lupo, Cosmo; Lloyd, Seth

    2015-03-01

    We show that, if the accessible information is used as a security quantifier, quantum channels with a certain symmetry can convey private messages at a tremendously high rate, as high as less than one bit below the rate of non-private classical communication. This result is obtained by exploiting the quantum data locking effect. The price to pay to achieve such a high private communication rate is that accessible information security is in general not composable. However, composable security holds against an eavesdropper who is forced to measure her share of the quantum system within a finite time after she gets it.

  10. Global crop exposure to critical high temperatures in the reproductive period: historical trends and future projections

    NASA Astrophysics Data System (ADS)

    Gourdji, Sharon M.; Sibley, Adam M.; Lobell, David B.

    2013-06-01

    Long-term warming trends across the globe have shifted the distribution of temperature variability, such that what was once classified as extreme heat relative to local mean conditions has become more common. This is also true for agricultural regions, where exposure to extreme heat, particularly during key growth phases such as the reproductive period, can severely damage crop production in ways that are not captured by most crop models. Here, we analyze exposure of crops to physiologically critical temperatures in the reproductive stage (Tcrit), across the global harvested areas of maize, rice, soybean and wheat. Trends for the 1980-2011 period show a relatively weak correspondence (r = 0.19) between mean growing season temperature and Tcrit exposure trends, emphasizing the importance of separate analyses for Tcrit. Increasing Tcrit exposure in the past few decades is apparent for wheat in Central and South Asia and South America, and for maize in many diverse locations across the globe. Maize had the highest percentage (15%) of global harvested area exposed to at least five reproductive days over Tcrit in the 2000s, although this value is somewhat sensitive to the exact temperature used for the threshold. While there was relatively little sustained exposure to reproductive days over Tcrit for the other crops in the past few decades, all show increases with future warming. Using projections from climate models we estimate that by the 2030s, 31, 16, and 11% respectively of maize, rice, and wheat global harvested area will be exposed to at least five reproductive days over Tcrit in a typical year, with soybean much less affected. Both maize and rice exhibit non-linear increases with time, with total area exposed for rice projected to grow from 8% in the 2000s to 27% by the 2050s, and maize from 15 to 44% over the same period. While faster development should lead to earlier flowering, which would reduce reproductive extreme heat exposure for wheat on a global basis

  11. Uncovering high-strain rate protection mechanism in nacre

    NASA Astrophysics Data System (ADS)

    Huang, Zaiwang; Li, Haoze; Pan, Zhiliang; Wei, Qiuming; Chao, Yuh J.; Li, Xiaodong

    2011-11-01

    Under high-strain-rate compression (strain rate ~103 s-1), nacre (mother-of-pearl) exhibits surprisingly high fracture strength vis-à-vis under quasi-static loading (strain rate 10-3 s-1). Nevertheless, the underlying mechanism responsible for such sharply different behaviors in these two loading modes remains completely unknown. Here we report a new deformation mechanism, adopted by nacre, the best-ever natural armor material, to protect itself against predatory penetrating impacts. It involves the emission of partial dislocations and the onset of deformation twinning that operate in a well-concerted manner to contribute to the increased high-strain-rate fracture strength of nacre. Our findings unveil that Mother Nature delicately uses an ingenious strain-rate-dependent stiffening mechanism with a purpose to fight against foreign attacks. These findings should serve as critical design guidelines for developing engineered body armor materials.

  12. Uncovering high-strain rate protection mechanism in nacre.

    PubMed

    Huang, Zaiwang; Li, Haoze; Pan, Zhiliang; Wei, Qiuming; Chao, Yuh J; Li, Xiaodong

    2011-01-01

    Under high-strain-rate compression (strain rate approximately 10(3) s(-1)), nacre (mother-of-pearl) exhibits surprisingly high fracture strength vis-à-vis under quasi-static loading (strain rate 10(-3) s(-1)). Nevertheless, the underlying mechanism responsible for such sharply different behaviors in these two loading modes remains completely unknown. Here we report a new deformation mechanism, adopted by nacre, the best-ever natural armor material, to protect itself against predatory penetrating impacts. It involves the emission of partial dislocations and the onset of deformation twinning that operate in a well-concerted manner to contribute to the increased high-strain-rate fracture strength of nacre. Our findings unveil that Mother Nature delicately uses an ingenious strain-rate-dependent stiffening mechanism with a purpose to fight against foreign attacks. These findings should serve as critical design guidelines for developing engineered body armor materials. PMID:22355664

  13. Uncovering high-strain rate protection mechanism in nacre

    PubMed Central

    Huang, Zaiwang; Li, Haoze; Pan, Zhiliang; Wei, Qiuming; Chao, Yuh J.; Li, Xiaodong

    2011-01-01

    Under high-strain-rate compression (strain rate ∼103 s−1), nacre (mother-of-pearl) exhibits surprisingly high fracture strength vis-à-vis under quasi-static loading (strain rate 10−3 s−1). Nevertheless, the underlying mechanism responsible for such sharply different behaviors in these two loading modes remains completely unknown. Here we report a new deformation mechanism, adopted by nacre, the best-ever natural armor material, to protect itself against predatory penetrating impacts. It involves the emission of partial dislocations and the onset of deformation twinning that operate in a well-concerted manner to contribute to the increased high-strain-rate fracture strength of nacre. Our findings unveil that Mother Nature delicately uses an ingenious strain-rate-dependent stiffening mechanism with a purpose to fight against foreign attacks. These findings should serve as critical design guidelines for developing engineered body armor materials. PMID:22355664

  14. FAST TRACK COMMUNICATION High rate straining of tantalum and copper

    NASA Astrophysics Data System (ADS)

    Armstrong, R. W.; Zerilli, F. J.

    2010-12-01

    High strain rate measurements reported recently for several tantalum and copper crystal/polycrystal materials are shown to follow dislocation mechanics-based constitutive relations, first at lower strain rates, for dislocation velocity control of the imposed plastic deformations and, then at higher rates, transitioning to nano-scale dislocation generation control by twinning or slip. For copper, there is the possibility of added-on slip dislocation displacements to be accounted for from the newly generated dislocations.

  15. The Ewe’s Reproductive Performance, Growth Rate and Carcass Quality of Lambs Kept in a Barn vs Those Kept under an Overhead Shelter

    PubMed Central

    Kuźnicka, Ewa; Rant, Witold

    2013-01-01

    A herd of polish lowland local sheep was divided into two equal groups: the first group was kept under an overhead shelter, and the second group was kept in a warm barn. The effect of maintenance on ewe’s reproductive performance, survival as well as the growth rate of lambs, and their carcasses quality was investigated. The lack of differences in fertility and prolificacy of ewes as well as in the survival and growth rate between the groups confirmed a good adaptation of Żelaźnieńska sheep to low temperature. Harsh environmental conditions did not cause a significant decrease of the body weight growth; however, they brought in an (insignificant) reduction of subcutaneous fat thickness and meatiness of the loin part of a lamb’s body. The fat content of carcasses obtained from lambs reared under the overhead shelter was significantly lower, with no differences of meat and bones contribution between the groups. PMID:25049778

  16. Putative extremely high rate of proteome innovation in lancelets might be explained by high rate of gene prediction errors

    PubMed Central

    Bányai, László; Patthy, László

    2016-01-01

    A recent analysis of the genomes of Chinese and Florida lancelets has concluded that the rate of creation of novel protein domain combinations is orders of magnitude greater in lancelets than in other metazoa and it was suggested that continuous activity of transposable elements in lancelets is responsible for this increased rate of protein innovation. Since morphologically Chinese and Florida lancelets are highly conserved, this finding would contradict the observation that high rates of protein innovation are usually associated with major evolutionary innovations. Here we show that the conclusion that the rate of proteome innovation is exceptionally high in lancelets may be unjustified: the differences observed in domain architectures of orthologous proteins of different amphioxus species probably reflect high rates of gene prediction errors rather than true innovation. PMID:27476717

  17. Reproductive biology of Syzygiella rubricaulis (Nees) Steph. (Adelanthaceae, Marchantiophyta), a liverwort disjunctly distributed in high-altitude Neotropical mountains.

    PubMed

    Maciel-Silva, A S; Gaspar, E P; da Conceição, F P; Dias Dos Santos, N; Pinheiro da Costa, D

    2016-07-01

    Syzygiella rubricaulis is a dioecious leafy liverwort disjunctly distributed and restricted to high-altitude mountains in the Neotropics and the Azores. This study is part of a larger project examining the phylogeography of S. rubricaulis in the Neotropics, and our main goals were to understand its reproductive biology, where sex expression occurs, if vegetative propagules are frequently found, how the sexes are distributed in populations, how frequently sporophytes are formed and what environmental conditions influence sexual expression. S. rubricaulis patches are mostly female, but all patches also contain non sex-expressing shoots. Out of 42 patches examined, 29 (69%) were sex-expressing: 25 were unisexual (21 female and four male) and four of mixed sex (two male-biased and two unbiased). At shoot level, out of 4200 shoots 18% were female and 7% male; among sex-expressing shoots, 73% were female, representing a sex ratio of 0.8 (female-biased). We encountered a total of 33 sporophytes in six patches (in Brazil, Venezuela and Ecuador). Leaf regenerants were found in one patch in Mexico. Low rates of sporophytes were likely related to low frequencies of male shoots and large distances between the sexes. As 25% of S. rubricaulis shoots expressed sex (occasionally producing sporophytes), we suggest that short-distance (and rarely long-distance) spore dispersal events occur in mountainous areas on a short-term basis. On a long-term basis, however, these events likely contribute to dynamic exchanges among populations in the Neotropics. PMID:26929143

  18. Rural and Urban High School Dropout Rates: Are They Different?

    ERIC Educational Resources Information Center

    Jordan, Jeffrey L.; Kostandini, Genti; Mykerezi, Elton

    2012-01-01

    This study estimates the high school dropout rate in rural and urban areas, the determinants of dropping out, and whether the differences in graduation rates have changed over time. We use geocoded data from two nationally representative panel household surveys (NLSY 97 and NLSY 79) and a novel methodology that corrects for biases in graduation…

  19. Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei)

    PubMed Central

    Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

    2016-01-01

    Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction. PMID:26808475

  20. Asexual Reproduction Does Not Apparently Increase the Rate of Chromosomal Evolution: Karyotype Stability in Diploid and Triploid Clonal Hybrid Fish (Cobitis, Cypriniformes, Teleostei).

    PubMed

    Majtánová, Zuzana; Choleva, Lukáš; Symonová, Radka; Ráb, Petr; Kotusz, Jan; Pekárik, Ladislav; Janko, Karel

    2016-01-01

    Interspecific hybridization, polyploidization and transitions from sexuality to asexuality considerably affect organismal genomes. Especially the last mentioned process has been assumed to play a significant role in the initiation of chromosomal rearrangements, causing increased rates of karyotype evolution. We used cytogenetic analysis and molecular dating of cladogenetic events to compare the rate of changes of chromosome morphology and karyotype in asexually and sexually reproducing counterparts in European spined loach fish (Cobitis). We studied metaphases of three sexually reproducing species and their diploid and polyploid hybrid clones of different age of origin. The material includes artificial F1 hybrid strains, representatives of lineage originated in Holocene epoch, and also individuals of an oldest known age to date (roughly 0.37 MYA). Thereafter we applied GISH technique as a marker to differentiate parental chromosomal sets in hybrids. Although the sexual species accumulated remarkable chromosomal rearrangements after their speciation, we observed no differences in chromosome numbers and/or morphology among karyotypes of asexual hybrids. These hybrids possess chromosome sets originating from respective parental species with no cytogenetically detectable recombinations, suggesting their integrity even in a long term. The switch to asexual reproduction thus did not provoke any significant acceleration of the rate of chromosomal evolution in Cobitis. Asexual animals described in other case studies reproduce ameiotically, while Cobitis hybrids described here produce eggs likely through modified meiosis. Therefore, our findings indicate that the effect of asexuality on the rate of chromosomal change may be context-dependent rather than universal and related to particular type of asexual reproduction. PMID:26808475

  1. Aminopeptidase activity in seminal plasma and effect of dilution rate on rabbit reproductive performance after insemination with an extender supplemented with buserelin acetate.

    PubMed

    Viudes-de-Castro, M P; Mocé, E; Lavara, R; Marco-Jiménez, F; Vicente, J S

    2014-06-01

    Ovulation induction in artificially inseminated rabbits by adding GnRH synthetic analogues in the seminal doses is a welfare-orientated method to induce ovulation in rabbits and could have some advantages in field practice. This study was conducted to determine the effect of male genotype on the aminopeptidase activity in rabbit seminal plasma and the effects of dilution rate of semen on availability and reproductive performance when buserelin acetate is added to the seminal dose. To study the aminopeptidase activity, 12 mature bucks belonging to a paternal line and 12 from a maternal line were used. The bucks from the paternal line were used to study the effect of dilution rate on the availability of buserelin acetate after 2 hours of dilution and on the reproductive performance of the doses after artificial insemination of 389 commercial crossbreed does. Aminopeptidase activity in seminal plasma is dependent on the male genotype. The paternal line resulted 27% more aminopeptidase activity than the maternal line (P < 0.05). On the other hand, semen diluted 1:20 exhibited a marked increase in the availability of buserelin acetate and the fertility in this group was significantly higher than females from dilution rate 1:5 group, which showed similar results to that of the negative control group (does inseminated with semen diluted 1:20 in non-GnRH-supplemented extender). We conclude that the bioavailability of buserelin acetate when added to the seminal dose appears to be determined by the activity of the existing aminopeptidases and is consequently affected by the dilution rate used to prepare the artificial insemination doses. PMID:24629591

  2. Teaching Plant Reproduction.

    ERIC Educational Resources Information Center

    Tolman, Marvin N., Ed.; Hardy, Garry R., Ed.

    2000-01-01

    Recommends using Amaryllis hippeastrum to teach young children about plant reproduction. Provides tips for growing these plants, discusses the fast growing rate of the plant, and explains the anatomy. (YDS)

  3. Effects of reproductive status and high ambient temperatures on the body temperature of a free-ranging basoendotherm.

    PubMed

    Levesque, Danielle L; Lobban, Kerileigh D; Lovegrove, Barry G

    2014-12-01

    Tenrecs (Order Afrosoricida) exhibit some of the lowest body temperatures (T b) of any eutherian mammal. They also have a high level of variability in both active and resting T bs and, at least in cool temperatures in captivity, frequently employ both short- and long-term torpor. The use of heterothermy by captive animals is, however, generally reduced during gestation and lactation. We present data long-term T b recordings collected from free-ranging S. setosus over the course of two reproductive seasons. In general, reproductive females had slightly higher (~32 °C) and less variable T b, whereas non-reproductive females and males showed both a higher propensity for torpor as well as lower (~30.5 °C) and more variable rest-phase T bs. Torpor expression defined using traditional means (using a threshold or cut-off T b) was much lower than predicted based on the high degree of heterothermy in captive tenrecs. However, torpor defined in this manner is likely to be underestimated in habitats where ambient temperature is close to T b. Our results caution against inferring metabolic states from T b alone and lend support to the recent call to define torpor in free-ranging animals based on mechanistic and not descriptive variables. In addition, lower variability in T b observed during gestation and lactation confirms that homeothermy is essential for reproduction in this species and probably for basoendothermic mammals in general. The relatively low costs of maintaining homeothermy in a sub-tropical environment might help shed light on how homeothermy could have evolved incrementally from an ancestral heterothermic condition. PMID:25155185

  4. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    PubMed Central

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  5. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli.

    PubMed

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S; Iguaz, Asunción; Periago, Paula M; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  6. High strain rate loading of polymeric foams and solid plastics

    NASA Astrophysics Data System (ADS)

    Dick, Richard D.; Chang, Peter C.; Fourney, William L.

    2000-04-01

    The split-Hopkinson pressure bar (SHPB) provided a technique to determine the high strain rate response for low density foams and solid ABS and polypropylene plastics. These materials are used in the interior safety panels of automobiles and crash test dummies. Because the foams have a very low impedance, polycarbonate bars were used to acquire the strain rate data in the 100 to 1600 l/s range. An aluminum SPHB setup was used to obtain the solid plastics data which covered strain rates of 1000 to 4000 l/s. The curves for peak strain rate versus peak stress for the foams over the test range studied indicates only a slight strain rate dependence. Peak strain rate versus peak stress curves for polypropylene shows a strain rate dependence up to about 1500 l/s. At that rate the solid poly propylene indicates no strain rate dependence. The ABS plastics are strain rate dependent up to 3500 l/s and then are independent at larger strain rates.

  7. Performance of High Flow Rate Samplers for Respirable Particle Collection

    PubMed Central

    Lee, Taekhee; Kim, Seung Won; Chisholm, William P.; Slaven, James; Harper, Martin

    2010-01-01

    The American Conference of Governmental Industrial hygienists (ACGIH) lowered the threshold limit value (TLV) for respirable crystalline silica (RCS) exposure from 0.05 to 0.025 mg m−3 in 2006. For a working environment with an airborne dust concentration near this lowered TLV, the sample collected with current standard respirable aerosol samplers might not provide enough RCS for quantitative analysis. Adopting high flow rate sampling devices for respirable dust containing silica may provide a sufficient amount of RCS to be above the limit of quantification even for samples collected for less than full shift. The performances of three high flow rate respirable samplers (CIP10-R, GK2.69, and FSP10) have been evaluated in this study. Eleven different sizes of monodisperse aerosols of ammonium fluorescein were generated with a vibrating orifice aerosol generator in a calm air chamber in order to determine the sampling efficiency of each sampler. Aluminum oxide particles generated by a fluidized bed aerosol generator were used to test (i) the uniformity of a modified calm air chamber, (ii) the effect of loading on the sampling efficiency, and (iii) the performance of dust collection compared to lower flow rate cyclones in common use in the USA (10-mm nylon and Higgins–Dewell cyclones). The coefficient of variation for eight simultaneous samples in the modified calm air chamber ranged from 1.9 to 6.1% for triplicate measures of three different aerosols. The 50% cutoff size (50dae) of the high flow rate samplers operated at the flow rates recommended by manufacturers were determined as 4.7, 4.1, and 4.8 μm for CIP10-R, GK2.69, and FSP10, respectively. The mass concentration ratio of the high flow rate samplers to the low flow rate cyclones decreased with decreasing mass median aerodynamic diameter (MMAD) and high flow rate samplers collected more dust than low flow rate samplers by a range of 2–11 times based on gravimetric analysis. Dust loading inside the high

  8. Performance of high flow rate samplers for respirable particle collection.

    PubMed

    Lee, Taekhee; Kim, Seung Won; Chisholm, William P; Slaven, James; Harper, Martin

    2010-08-01

    The American Conference of Governmental Industrial hygienists (ACGIH) lowered the threshold limit value (TLV) for respirable crystalline silica (RCS) exposure from 0.05 to 0.025 mg m(-3) in 2006. For a working environment with an airborne dust concentration near this lowered TLV, the sample collected with current standard respirable aerosol samplers might not provide enough RCS for quantitative analysis. Adopting high flow rate sampling devices for respirable dust containing silica may provide a sufficient amount of RCS to be above the limit of quantification even for samples collected for less than full shift. The performances of three high flow rate respirable samplers (CIP10-R, GK2.69, and FSP10) have been evaluated in this study. Eleven different sizes of monodisperse aerosols of ammonium fluorescein were generated with a vibrating orifice aerosol generator in a calm air chamber in order to determine the sampling efficiency of each sampler. Aluminum oxide particles generated by a fluidized bed aerosol generator were used to test (i) the uniformity of a modified calm air chamber, (ii) the effect of loading on the sampling efficiency, and (iii) the performance of dust collection compared to lower flow rate cyclones in common use in the USA (10-mm nylon and Higgins-Dewell cyclones). The coefficient of variation for eight simultaneous samples in the modified calm air chamber ranged from 1.9 to 6.1% for triplicate measures of three different aerosols. The 50% cutoff size ((50)d(ae)) of the high flow rate samplers operated at the flow rates recommended by manufacturers were determined as 4.7, 4.1, and 4.8 microm for CIP10-R, GK2.69, and FSP10, respectively. The mass concentration ratio of the high flow rate samplers to the low flow rate cyclones decreased with decreasing mass median aerodynamic diameter (MMAD) and high flow rate samplers collected more dust than low flow rate samplers by a range of 2-11 times based on gravimetric analysis. Dust loading inside the

  9. Slow rate of molecular evolution in high-elevation hummingbirds.

    PubMed

    Bleiweiss, R

    1998-01-20

    Estimates of relative rates of molecular evolution from a DNA-hybridization phylogeny for 26 hummingbird species provide evidence for a negative association between elevation and rate of single-copy genome evolution. This effect of elevation on rate remains significant even after taking into account a significant negative association between body mass and molecular rate. Population-level processes do not appear to account for these patterns because (i) all hummingbirds breed within their first year and (ii) the more extensive subdivision and speciation of bird populations living at high elevations predicts a positive association between elevation and rate. The negative association between body mass and molecular rate in other organisms has been attributed to higher mutation rates in forms with higher oxidative metabolism. As ambient oxygen tensions and temperature decrease with elevation, the slow rate of molecular evolution in high-elevation hummingbirds also may have a metabolic basis. A slower rate of single-copy DNA change at higher elevations suggests that the dynamics of molecular evolution cannot be separated from the environmental context. PMID:9435240

  10. Reproductive Hazards

    MedlinePlus

    ... such as lead and mercury Chemicals such as pesticides Cigarettes Some viruses Alcohol For men, a reproductive hazard can affect the sperm. For a woman, a reproductive hazard can cause different effects during pregnancy, depending on when she is exposed. ...

  11. Reproductive Hazards

    MedlinePlus

    ... and female reproductive systems play a role in pregnancy. Problems with these systems can affect fertility and ... a reproductive hazard can cause different effects during pregnancy, depending on when she is exposed. During the ...

  12. Solidification at the High and Low Rate Extreme

    SciTech Connect

    Halim Meco

    2004-12-19

    The microstructures formed upon solidification are strongly influenced by the imposed growth rates on an alloy system. Depending on the characteristics of the solidification process, a wide range of growth rates is accessible. The prevailing solidification mechanisms, and thus the final microstructure of the alloy, are governed by these imposed growth rates. At the high rate extreme, for instance, one can have access to novel microstructures that are unattainable at low growth rates. While the low growth rates can be utilized for the study of the intrinsic growth behavior of a certain phase growing from the melt. Although the length scales associated with certain processes, such as capillarity, and the diffusion of heat and solute, are different at low and high rate extremes, the phenomena that govern the selection of a certain microstructural length scale or a growth mode are the same. Consequently, one can analyze the solidification phenomena at both high and low rates by using the same governing principles. In this study, we examined the microstructural control at both low and high extremes. For the high rate extreme, the formation of crystalline products and factors that control the microstructure during rapid solidification by free-jet melt spinning are examined in Fe-Si-B system. Particular attention was given to the behavior of the melt pool at different quench-wheel speeds. Since the solidification process takes place within the melt-pool that forms on the rotating quench-wheel, we examined the influence of melt-pool dynamics on nucleation and growth of crystalline solidification products and glass formation. High-speed imaging of the melt-pool, analysis of ribbon microstructure, and measurement of ribbon geometry and surface character all indicate upper and lower limits for melt-spinning rates for which nucleation can be avoided, and fully amorphous ribbons can be achieved. Comparison of the relevant time scales reveals that surface-controlled melt

  13. Importation and Recombination Are Responsible for the Latest Emergence of Highly Pathogenic Porcine Reproductive and Respiratory Syndrome Virus in China

    PubMed Central

    Zhao, Kuan; Ye, Chao; Chang, Xiao-Bo; Jiang, Cheng-Gang; Wang, Shu-Jie; Cai, Xue-Hui; Tong, Guang-Zhi; Tian, Zhi-Jun

    2015-01-01

    In China, a majority of the highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRSV) strains were seeded by the 2006 outbreak. However, the most recently emerged (2013-2014) HP-PRRSV strain has a very different genetic background. It is a NADC30-like PRRSV strain recently introduced from North America that has undergone genetic exchange with the classic HP-PRRSV strains in China. Subsequent isolation and characterization of this variant suggest high pathogenicity, so it merits special attention in control and vaccine strategies. PMID:26246582

  14. Time reproduction performance is associated with age and working memory in high-functioning youth with autism spectrum disorder.

    PubMed

    Brenner, Laurie A; Shih, Vivian H; Colich, Natalie L; Sugar, Catherine A; Bearden, Carrie E; Dapretto, Mirella

    2015-02-01

    Impaired temporal processing has historically been viewed as a hallmark feature of attention deficit hyperactivity disorder. Recent evidence suggests temporal processing deficits may also be characteristic of autism spectrum disorder (ASD). However, little is known about the factors that impact temporal processing in children with ASD. The purpose of this study was to assess the effects of co-morbid attention problems, working memory (WM), age, and their interactions, on time reproduction in youth with and without ASD. Twenty-seven high-functioning individuals with ASD and 25 demographically comparable typically developing individuals (ages 9-17; 85% male) were assessed on measures of time reproduction, auditory WM, and inattention/hyperactivity. The time reproduction task required depression of a computer key to mimic interval durations of 4, 8, 12, 16, or 20 sec. Mixed effects regression analyses were used to model accuracy and variability of time reproduction as functions of diagnostic group, interval duration, age, WM, and inattention/hyperactivity. A significant group by age interaction was detected for accuracy, with the deficit in the ASD group being greater in younger children. There was a significant group by WM interaction for consistency, with the effects of poor WM on performance consistency being more pronounced in youth with ASD. All participants tended to underestimate longer interval durations and to be less consistent for shorter interval durations; these effects appeared more pronounced in those who were younger or who had poorer WM performance. Inattention/hyperactivity symptoms in the ASD group were not related to either accuracy or consistency. This study highlights the potential value of temporal processing as an intermediate trait of relevance to multiple neurodevelopmental disorders. PMID:25078724

  15. Authoritative School Climate and High School Dropout Rates

    ERIC Educational Resources Information Center

    Jia, Yuane; Konold, Timothy R.; Cornell, Dewey

    2016-01-01

    This study tested the association between school-wide measures of an authoritative school climate and high school dropout rates in a statewide sample of 315 high schools. Regression models at the school level of analysis used teacher and student measures of disciplinary structure, student support, and academic expectations to predict overall high…

  16. High strain-rate plastic flow in Fe and Al

    NASA Astrophysics Data System (ADS)

    Smith, Raymond; Eggert, Jon; Rudd, Robert; Bolme, Cynthia; Collins, Gilbert

    2011-06-01

    Understanding the nature and time-dependence of material deformation at high strain rates is an important goal in condensed matter physics. Under dynamic loading, the rate of plastic strain is determined by the flow of dislocations through the crystal lattice and is a complex function of time, distance, sample purity, temperature, internal stresses, microstructure and strain rate. Under shock compression time-dependent plasticity is typically inferred by fitting elastic precursor stresses as a function of propagation distance with a phenomenologically based dislocation kinetics model. We employ a laser-driven ramp wave loading technique to compress 6-70 micron thick samples of bcc-Fe and fcc-Al over a strain rate range of 1e6-1e8 1/s. Our data show that for fixed sample thickness, stresses associated the onset of plasticity are highly dependent on the strain rate of compression and do not readily fit into the elastic stress - distance evolution descriptive of instantaneous shock loading. We find that the elastic stress at the onset of plasticity is well correlated with the strain rate at the onset of plastic flow for both shock- and ramp-wave experiments. Our data, combined with data from other dynamic compression platforms, reveal a sharp increase in the peak elastic stress at high strain rates, consistent with a transition in dislocation flow dominated by phonon drag. smith248@llnl.gov

  17. High-repetition-rate short-pulse gas discharge.

    PubMed

    Tulip, J; Seguin, H; Mace, P N

    1979-09-01

    A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW. PMID:18699678

  18. Blast furnace coal injection system design for high rates

    SciTech Connect

    Snowden, B.

    1994-12-31

    Coal injection into blast furnaces is now well established as a basic technology. However, high rates of coal injection between 300 and 500 lb/thm (160 to 250 kg/thm) are a rarity. Special consideration must be given to the overall concept regarding strategic coal storage, expected equipment reliability, and back-up available to prevent furnace problems, should any of the coal feeding systems fail. British Steel and Simon Macawber now have considerable operational experience at high rates for sustained periods. The paper will discuss the points to be considered and describe the ATSI-Simon Macawber approach to providing a high level of confidence in the coal injection system.

  19. Evolution of High Tooth Replacement Rates in Sauropod Dinosaurs

    PubMed Central

    Smith, Kathlyn M.; Fisher, Daniel C.; Wilson, Jeffrey A.

    2013-01-01

    Background Tooth replacement rate can be calculated in extinct animals by counting incremental lines of deposition in tooth dentin. Calculating this rate in several taxa allows for the study of the evolution of tooth replacement rate. Sauropod dinosaurs, the largest terrestrial animals that ever evolved, exhibited a diversity of tooth sizes and shapes, but little is known about their tooth replacement rates. Methodology/Principal Findings We present tooth replacement rate, formation time, crown volume, total dentition volume, and enamel thickness for two coexisting but distantly related and morphologically disparate sauropod dinosaurs Camarasaurus and Diplodocus. Individual tooth formation time was determined by counting daily incremental lines in dentin. Tooth replacement rate is calculated as the difference between the number of days recorded in successive replacement teeth. Each tooth family in Camarasaurus has a maximum of three replacement teeth, whereas each Diplodocus tooth family has up to five. Tooth formation times are about 1.7 times longer in Camarasaurus than in Diplodocus (315 vs. 185 days). Average tooth replacement rate in Camarasaurus is about one tooth every 62 days versus about one tooth every 35 days in Diplodocus. Despite slower tooth replacement rates in Camarasaurus, the volumetric rate of Camarasaurus tooth replacement is 10 times faster than in Diplodocus because of its substantially greater tooth volumes. A novel method to estimate replacement rate was developed and applied to several other sauropodomorphs that we were not able to thin section. Conclusions/Significance Differences in tooth replacement rate among sauropodomorphs likely reflect disparate feeding strategies and/or food choices, which would have facilitated the coexistence of these gigantic herbivores in one ecosystem. Early neosauropods are characterized by high tooth replacement rates (despite their large tooth size), and derived titanosaurs and diplodocoids independently

  20. High lifetime and reproductive performance of sows on southern European Union commercial farms can be predicted by high numbers of pigs born alive in parity one.

    PubMed

    Iida, R; Piñeiro, C; Koketsu, Y

    2015-05-01

    Our objectives were 1) to compare reproductive performance across parity and lifetime performance in sow groups categorized by the number of pigs born alive (PBA) in parity 1 and 2) to examine the factors associated with more PBA in parity 1. We analyzed 476,816 parity records and 109,373 lifetime records of sows entered into 125 herds from 2008 to 2010. Sows were categorized into 4 groups based on the 10th, 50th, and 90th percentiles of PBA in parity 1 as follows: 7 pigs or fewer, 8 to 11 pigs, 12 to 14 pigs, and 15 pigs or more. Generalized linear models were applied to the data. For reproductive performance across parity, sows that had 15 or more PBA in parity 1 had 0.5 to 1.8 more PBA in any subsequent parity than the other 3 PBA groups ( P< 0.05). In addition, they had 2.8 to 5.4% higher farrowing rates in parities 1 through 3 than sows that had 7 or fewer PBA (P < 0.05). However, there were no differences between the sow PBA groups for weaning-to-first-mating interval in any parity (P ≥ 0.37). For lifetime performance, sows that had 15 or more PBA in parity 1 had 4.4 to 26.1 more lifetime PBA than sows that had 14 or fewer PBA (P < 0.05). Also, for sows that had 14 or fewer PBA in parity 1, those that were first mated at 229 d old (25th percentile) or earlier had 2.9 to 3.3 more lifetime PBA than those first mated at 278 d old (75th percentile) or later (P < 0.05). Factors associated with fewer PBA in parity 1 were summer mating and lower age of gilts at first mating (AFM; P < 0.05) but not reservice occurrences (P = 0.34). Additionally, there was a 2-way interaction between mated month groups and AFM for PBA in parity 1 (P < 0.05); PBA in parity 1 sows mated from July to December increased nonlinearly by 0.3 to 0.4 pigs when AFM increased from 200 to 310 d old (P < 0.05). However, the same rise in AFM had no significant effect on the PBA of sows mated between January and June (P ≥ 0.17). In conclusion, high PBA in parity 1 can be used to predict that a

  1. Social Reproduction and the Student Decision to Follow the Louisiana Career/Basic Core Diploma Path at a Large, Affluent High School in Northeastern Louisiana

    ERIC Educational Resources Information Center

    Whittock, Tammy

    2013-01-01

    Through this mixed-method study, the researcher investigated social reproduction in a student's decision to follow the Louisiana Career/Basic Core Diploma Path. In 2008-2009, Louisiana's cohort graduation rate was 67.3%, which was well below the national average of 75.5%, ranking Louisiana forty-sixth in the country. This rate led to the…

  2. High rate and stable cycling of lithium metal anode

    SciTech Connect

    Qian, Jiangfeng; Henderson, Wesley A.; Xu, Wu; Bhattacharya, Priyanka; Engelhard, Mark H.; Borodin, Oleg; Zhang, Jiguang

    2015-02-20

    Lithium (Li) metal is an ideal anode material for rechargeable batteries. However, dendritic Li growth and limited Coulombic efficiency (CE) during repeated Li deposition/stripping processes have prevented the application of this anode in rechargeable Li metal batteries, especially for use at high current densities. Here, we report that the use of highly concentrated electrolytes composed of ether solvents and the lithium bis(fluorosulfonyl)imide (LiFSI) salt enables the high rate cycling of a Li metal anode at high CE (up to 99.1 %) without dendrite growth. With 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte, a Li|Li cell can be cycled at high rates (10 mA cm-2) for more than 6000 cycles with no increase in the cell impedance, and a Cu|Li cell can be cycled at 4 mA cm-2 for more than 1000 cycles with an average CE of 98.4%. These excellent high rate performances can be attributed to the increased solvent coordination and increased availability of Li+ concentration in the electrolyte. Lastly, further development of this electrolyte may lead to practical applications for Li metal anode in rechargeable batteries. The fundamental mechanisms behind the high rate ion exchange and stability of the electrolytes also shine light on the stability of other electrochemical systems.

  3. High Rate and Stable Cycling of Lithium Metal Anode

    SciTech Connect

    Qian, Jiangfeng; Henderson, Wesley A.; Xu, Wu; Bhattacharya, Priyanka; Engelhard, Mark H.; Borodin, Oleg; Zhang, Jiguang

    2015-02-20

    Lithium (Li) metal is an ideal anode material for rechargeable batteries. However, dendritic Li growth and limited Coulombic efficiency (CE) during repeated Li deposition/stripping processes have prevented the application of this anode in rechargeable Li metal batteries, especially for use at high current densities. Herein, we report that the use of highly concentrated electrolytes composed of ether solvents and the lithium bis(fluorosulfonyl)imide (LiFSI) salt enables the high rate cycling of a Li metal anode at high CE (up to 99.1 %) without dendrite growth. With 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte, a Li|Li cell can be cycled at high rates (10 mA cm-2) for more than 6000 cycles with no increase in the cell impedance, and a Cu|Li cell can be cycled at 4 mA cm-2 for more than 1000 cycles with an average CE of 98.4%. These excellent high rate performances can be attributed to the increased solvent coordination and increased availability of Li+ concentration in the electrolyte. Further development of this electrolyte may lead to practical applications for Li metal anode in rechargeable batteries. The fundamental mechanisms behind the high rate ion exchange and stability of the electrolytes also shine light on the stability of other electrochemical systems.

  4. High rate and stable cycling of lithium metal anode

    DOE PAGESBeta

    Qian, Jiangfeng; Henderson, Wesley A.; Xu, Wu; Bhattacharya, Priyanka; Engelhard, Mark H.; Borodin, Oleg; Zhang, Jiguang

    2015-02-20

    Lithium (Li) metal is an ideal anode material for rechargeable batteries. However, dendritic Li growth and limited Coulombic efficiency (CE) during repeated Li deposition/stripping processes have prevented the application of this anode in rechargeable Li metal batteries, especially for use at high current densities. Here, we report that the use of highly concentrated electrolytes composed of ether solvents and the lithium bis(fluorosulfonyl)imide (LiFSI) salt enables the high rate cycling of a Li metal anode at high CE (up to 99.1 %) without dendrite growth. With 4 M LiFSI in 1,2-dimethoxyethane (DME) as the electrolyte, a Li|Li cell can be cycledmore » at high rates (10 mA cm-2) for more than 6000 cycles with no increase in the cell impedance, and a Cu|Li cell can be cycled at 4 mA cm-2 for more than 1000 cycles with an average CE of 98.4%. These excellent high rate performances can be attributed to the increased solvent coordination and increased availability of Li+ concentration in the electrolyte. Lastly, further development of this electrolyte may lead to practical applications for Li metal anode in rechargeable batteries. The fundamental mechanisms behind the high rate ion exchange and stability of the electrolytes also shine light on the stability of other electrochemical systems.« less

  5. High Strain Rate Behavior of Polymer Matrix Composites Analyzed

    NASA Technical Reports Server (NTRS)

    Goldberg, Robert K.; Roberts, Gary D.

    2001-01-01

    Procedures for modeling the high-speed impact of composite materials are needed for designing reliable composite engine cases that are lighter than the metal cases in current use. The types of polymer matrix composites that are likely to be used in such an application have a deformation response that is nonlinear and that varies with strain rate. To characterize and validate material models that could be used in the design of impactresistant engine cases, researchers must obtain material data over a wide variety of strain rates. An experimental program has been carried out through a university grant with the Ohio State University to obtain deformation data for a representative polymer matrix composite for strain rates ranging from quasi-static to high rates of several hundred per second. This information has been used to characterize and validate a constitutive model that was developed at the NASA Glenn Research Center.

  6. Study of High Strain Rate Response of Composites

    NASA Technical Reports Server (NTRS)

    Gilat, Amos

    2003-01-01

    The objective of the research was to continue the experimental study of the effect of strain rate on mechanical response (deformation and failure) of epoxy resins and carbon fibers/epoxy matrix composites, and to initiate a study of the effects of temperature by developing an elevated temperature test. The experimental data provide the information needed for NASA scientists for the development of a nonlinear, rate dependent deformation and strength models for composites that can subsequently be used in design. This year effort was directed into testing the epoxy resin. Three types of epoxy resins were tested in tension and shear at various strain rates that ranges from 5 x 10(exp -5), to 1000 per second. Pilot shear experiments were done at high strain rate and an elevated temperature of 80 C. The results show that all, the strain rate, the mode of loading, and temperature significantly affect the response of epoxy.

  7. THE AMERICAN HIGH SCHOOL GRADUATION RATE: TRENDS AND LEVELS*

    PubMed Central

    Heckman, James J.; LaFontaine, Paul A.

    2009-01-01

    This paper applies a unified methodology to multiple data sets to estimate both the levels and trends in U.S. high school graduation rates. We establish that (a) the true rate is substantially lower than widely used measures; (b) it peaked in the early 1970s; (c) majority/minority differentials are substantial and have not converged for 35 years; (d) lower post-1970 rates are not solely due to increasing immigrant and minority populations; (e) our findings explain part of the slowdown in college attendance and rising college wage premiums; and (f) widening graduation differentials by gender help explain increasing male-female college attendance gaps. PMID:20625528

  8. High-Strain-Rate Compression Testing of Ice

    NASA Technical Reports Server (NTRS)

    Shazly, Mostafa; Prakash, Vikas; Lerch, Bradley A.

    2006-01-01

    In the present study a modified split Hopkinson pressure bar (SHPB) was employed to study the effect of strain rate on the dynamic material response of ice. Disk-shaped ice specimens with flat, parallel end faces were either provided by Dartmouth College (Hanover, NH) or grown at Case Western Reserve University (Cleveland, OH). The SHPB was adapted to perform tests at high strain rates in the range 60 to 1400/s at test temperatures of -10 and -30 C. Experimental results showed that the strength of ice increases with increasing strain rates and this occurs over a change in strain rate of five orders of magnitude. Under these strain rate conditions the ice microstructure has a slight influence on the strength, but it is much less than the influence it has under quasi-static loading conditions. End constraint and frictional effects do not influence the compression tests like they do at slower strain rates, and therefore the diameter/thickness ratio of the samples is not as critical. The strength of ice at high strain rates was found to increase with decreasing test temperatures. Ice has been identified as a potential source of debris to impact the shuttle; data presented in this report can be used to validate and/or develop material models for ice impact analyses for shuttle Return to Flight efforts.

  9. Effect of fixed-time embryo transfer on reproductive efficiency in high-producing repeat-breeder Holstein cows.

    PubMed

    Rodrigues, C A; Teixeira, A A; Ferreira, R M; Ayres, H; Mancilha, R F; Souza, A H; Baruselli, P S

    2010-04-01

    pregnancy loss [PGF-Estrus=11.9% (5/42), FTET-CL=9.0% (6/67); P=0.62] and circulating progesterone concentration at embryo transfer [PGF-Estrus=4.02+/-0.52 ng/mL (n=25), FTET-CL=3.33+/-0.32 ng/mL (n=27); P=0.25] among these treatments. The presence of CL at the beginning of FTET protocol resulted greater transferred-to-treated rate [FTET-CL=75.0% (156/208) vs. FTET-NoCL=61.2% (131/214); P=0.003], but showed no effect on pregnancy rate at 60 days [FTET-CL=29.3% (61/208) vs. FTET-NoCL=22.9% (49/214); P=0.13], pregnancy loss [FTET-CL=9.0% (6/67) vs. FTET-NoCL=2.0% (1/50); P=0.15] and circulating progesterone concentration at ET [FTET-CL=3.33+/-0.32 ng/mL (n=27) compared to FTET-NoCL=3.44+/-0.40 ng/mL (n=2 9); P=0.82]. In conclusion, the protocol for synchronization of time of ovulation using norgestomet ear implant, EB and eCG increased recipients transferred-to-treated and pregnancy rates in high-producing repeat-breeder Holstein cows. Also, recipients without CL at the beginning of the time of ovulation synchronization treatment resulted in similar pregnancy rate as recipients with CL submitted to FTET protocol. Thus, the suggested protocol allowed the performance of FTET, without the need for detection of estrus, simplifying the reproductive management and increasing the reproductive efficiency in repeat-breeder Holstein recipients. PMID:19640661

  10. Semi-solid electrodes having high rate capability

    DOEpatents

    Chiang, Yet-Ming; Duduta, Mihai; Holman, Richard; Limthongkul, Pimpa; Tan, Taison

    2016-07-05

    Embodiments described herein relate generally to electrochemical cells having high rate capability, and more particularly to devices, systems and methods of producing high capacity and high rate capability batteries having relatively thick semi-solid electrodes. In some embodiments, an electrochemical cell includes an anode, a semi-solid cathode that includes a suspension of an active material and a conductive material in a liquid electrolyte, and an ion permeable membrane disposed between the anode and the cathode. The semi-solid cathode has a thickness in the range of about 250 .mu.m-2,500 .mu.m, and the electrochemical cell has an area specific capacity of at least 5 mAh/cm.sup.2 at a C-rate of C/2.