1,692 research outputs found

    SMMR simulator radiative transfer calibration model. 1: Derivation

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    There are no author-identified significant results in this report

    The evolution of extraordinary self-sacrifice

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    From a theoretical perspective, individuals are expected to sacrifice their welfare only when the benefits outweigh the costs. In nature, however, the costs of altruism and spite can be extreme, as in cases of irreversible sterility and self-destructive weaponry. Here we show that “extraordinary” self-sacrifice—in which actors pay costs that exceed the benefits they give or the costs they impose on recipients—can evolve in structured populations, where social actions bring secondary benefits to neighboring kin. When given information about dispersal, sedentary actors evolve extraordinary altruism towards dispersing kin. Likewise, when given information about dispersal and kinship, sedentary actors evolve extraordinary spite towards sedentary nonkin. Our results can thus be summed up by a simple rule: extraordinary self-sacrifice evolves when the actor’s neighbors are close kin and the recipient’s neighbors are not

    A guidance and control assessment of three vertical landing options for RLV

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    The National Aeronautics and Space Administration is considering a vertical lander as a candidate concept for a single-stage-to-orbit reusable launch vehicle (RLV). Three strategies for guiding and controlling the inversion of a reentering RLV from a nose-first attitude to a vertical landing attitude are suggested. Each option is simulated from a common reentry state to touchdown, using a common guidance algorithm and different controllers. Results demonstrate the characteristics that typify and distinguish each concept and help to identify peculiar problems, level of guidance and control sophistication required, feasibility concerns, and areas in which stringent subsystem requirements will be imposed by guidance and control

    The Influence of Specimen Thickness on the High Temperature Corrosion Behavior of CMSX-4 during Thermal-Cycling Exposure

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    CMSX-4 is a single-crystalline Ni-base superalloy designed to be used at very high temperatures and high mechanical loadings. Its excellent corrosion resistance is due to external alumina-scale formation, which however can become less protective under thermal-cycling conditions. The metallic substrate in combination with its superficial oxide scale has to be considered as a composite suffering high stresses. Factors like different coefficients of thermal expansion between oxide and substrate during temperature changes or growing stresses affect the integrity of the oxide scale. This must also be strongly influenced by the thickness of the oxide scale and the substrate as well as the ability to relief such stresses, e.g., by creep deformation. In order to quantify these effects, thin-walled specimens of different thickness (t = 100500 lm) were prepared. Discontinuous measurements of their mass changes were carried out under thermal-cycling conditions at a hot dwell temperature of 1100 C up to 300 thermal cycles. Thin-walled specimens revealed a much lower oxide-spallation rate compared to thick-walled specimens, while thinwalled specimens might show a premature depletion of scale-forming elements. In order to determine which of these competetive factor is more detrimental in terms of a component’s lifetime, the degradation by internal precipitation was studied using scanning electron microscopy (SEM) in combination with energy-dispersive X-ray spectroscopy (EDS). Additionally, a recently developed statistical spallation model was applied to experimental data [D. Poquillon and D. Monceau, Oxidation of Metals, 59, 409–431 (2003)]. The model describes the overall mass change by oxide scale spallation during thermal cycling exposure and is a useful simulation tool for oxide scale spallation processes accounting for variations in the specimen geometry. The evolution of the net-mass change vs. the number of thermal cycles seems to be strongly dependent on the sample thickness

    Magnetospheric considerations for solar system ice state

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    The current lattice configuration of the water ice on the surfaces of the inner satellites of Jupiter and Saturn is likely shaped by many factors. But laboratory experiments have found that energetic proton irradiation can cause a transition in the structure of pure water ice from crystalline to amorphous. It is not known to what extent this process is competitive with other processes in solar system contexts. For example, surface regions that are rich in water ice may be too warm for this effect to be important, even if the energetic proton bombardment rate is very high. In this paper, we make predictions, based on particle flux levels and other considerations, about where in the magnetospheres of Jupiter and Saturn the ∌MeV proton irradiation mechanism should be most relevant. Our results support the conclusions of Hansen and McCord (2004), who related relative level of radiation on the three outer Galilean satellites to the amorphous ice content within the top 1 mm of surface. We argue here that if magnetospheric effects are considered more carefully, the correlation is even more compelling. Crystalline ice is by far the dominant ice state detected on the inner Saturnian satellites and, as we show here, the flux of bombarding energetic protons onto these bodies is much smaller than at the inner Jovian satellites. Therefore, the ice on the Saturnian satellites also corroborates the correlation

    Prevalence and Correlates of Primary Infertility in Mysore, India

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    Background & objectives: There are sparse data on the prevalence of primary infertility in India and almost none from Southern India. This study describes the correlates and prevalence of primary infertility among young women in Mysore, India. Methods: The baseline data were collected between November 2005 through March 2006, among 897 sexually active women, aged 15-30 yr, for a study investigating the relationship of bacterial vaginosis and acquisition of herpes simplex virus type-2 (HSV-2) infection. A secondary data analysis of the baseline data was undertaken. Primary infertility was defined as having been married for longer than two years, not using contraception and without a child. Logistic regression was used to examine factors associated with primary infertility. Results: The mean age of the women was 25.9 yr (range: 16-30 yr) and the prevalence of primary infertility was 12.6 per cent [95% Confidence Interval (CI): 10.5-15.0%]. The main factor associated with primary infertility was HSV-2 seropositivity (adjusted odds ratio: 3.41; CI: 1.86, 6.26). Interpretation & conclusions: The estimated prevalence of primary infertility among women in the study was within the range reported by the WHO and similar to other estimates from India. Further research is needed to examine the role of HSV-2 in primary infertility

    The Epidemiology of Herpes Simplex Virus Type-2 Infection among Pregnant Women in Rural Mysore Taluk, India

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    To assess the prevalence and determinants of herpes simplex virus type 2 (HSV-2) infections among pregnant women attending mobile antenatal health clinic in rural villages in Mysore Taluk, India. Methods. Between January and September 2009, 487 women from 52 villages participated in this study. Each participant consented to provide a blood sample for HSV-2 and HIV testing and underwent an interviewer-administered questionnaire. Results. HSV-2 prevalence was 6.7% (95% confidence interval (CI) 4.4–9.0), and one woman tested positive for HIV.The median age of women was 20 years and 99% of women reported having a single lifetime sex partner.Women whose sex partner traveled away from home had 2.68 (CI: 1.13–6.34) times the odds of being HSV-2 seropositive compared to women whose sex partner did not travel. Having experienced genital lesions was also associated with HSV-2 infection ( value = 0.08). Conclusion.The 6.7% HSV-2 prevalence was similar to results obtained in studies among pregnant women in other parts of India. It appeared that most women in this study contracted HSV-2 from their spouses and few regularly used condoms. This finding highlights the need for public health policies to increase awareness and education about prevention methods among women and men living in rural India

    Performance of BVBlue Rapid Test in Detecting Bacterial Vaginosis among Women in Mysore, India

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    Bacterial vaginosis (BV) is the most common cause of abnormal vaginal discharge in reproductive age women. It is associated with increased susceptibility to HIV/STI and adverse birth outcomes. Diagnosis of BV in resource-poor settings like India is challenging. With little laboratory infrastructure there is a need for objective point-of-care diagnostic tests. Vaginal swabs were collected from women 18 years and older, with a vaginal pH \u3e 4.5 attending a reproductive health clinic. BV was diagnosed with Amsel’s criteria, Nugent scores, and the OSOM BVBlue test. Study personnel were blinded to test results. There were 347 participants enrolled between August 2009 and January 2010. BV prevalence was 45.1% (95% confidence interval (CI): 41.5%–52.8%) according to Nugent score. When compared with Nugent score, the sensitivity, specificity, positive predictive value, negative predictive value for Amsel’s criteria and BVBlue were 61.9%, 88.3%, 81.5%, 73.7% and 38.1%, 92.7%, 82.1%, 63.9%, respectively. Combined with a “whiff” test, the performance of BVBlue increased sensitivity to 64.4% and negative predictive value to 73.8%. Despite the good specificity, poor sensitivity limits the usefulness of the BVBlue as a screening test in this population. There is a need to examine the usefulness of this test in other Indian populations

    STRING: known and predicted protein–protein associations, integrated and transferred across organisms

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    A full description of a protein's function requires knowledge of all partner proteins with which it specifically associates. From a functional perspective, ‘association’ can mean direct physical binding, but can also mean indirect interaction such as participation in the same metabolic pathway or cellular process. Currently, information about protein association is scattered over a wide variety of resources and model organisms. STRING aims to simplify access to this information by providing a comprehensive, yet quality-controlled collection of protein–protein associations for a large number of organisms. The associations are derived from high-throughput experimental data, from the mining of databases and literature, and from predictions based on genomic context analysis. STRING integrates and ranks these associations by benchmarking them against a common reference set, and presents evidence in a consistent and intuitive web interface. Importantly, the associations are extended beyond the organism in which they were originally described, by automatic transfer to orthologous protein pairs in other organisms, where applicable. STRING currently holds 730 000 proteins in 180 fully sequenced organisms, and is available at http://string.embl.de/
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