1,374 research outputs found

    High-pressure calorimeter chamber tests for liquid oxygen/kerosene (LOX/RP-1) rocket combustion

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    An experimental program was conducted to investigate the rocket combustion and heat transfer characteristics of liquid oxygen/kerosene (LOX/RP-1) mixtures at high chamber pressures. Two water-cooled calorimeter chambers of different combustion lengths were tested using 37- and 61-element oxidizer-fuel-oxidizer triplet injectors. The tests were conducted at nominal chamber pressures of 4.1, 8.3, and 13.8 MPa abs (600, 1200, and 2000 psia). Heat flux Q/A data were obtained for the entire calorimeter length for oxygen/fuel mixture ratios of 1.8 to 3.3. Test data at 4.1 MPa abs compared favorably with previous test data from another source. Using an injector with a fuel-rich outer zone reduced the throat heat flux by 47 percent with only a 4.5 percent reduction in the characteristic exhaust velocity efficiency C* sub eff. The throat heat transfer coefficient was reduced approximately 40 percent because of carbon deposits on the chamber wall

    Unexplained Aspects of Anemia of Inflammation

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    Anemia of inflammation (AI), also known as anemia of chronic inflammation or anemia of chronic disease was described over 50 years ago as anemia in association with clinically overt inflammatory disease, and the findings of low plasma iron, decreased bone marrow sideroblasts and increased reticuloendothelial iron. Pathogenic features underlying AI include a mild shortening of red cell survival, impaired erythropoietin production, blunted responsiveness of the marrow to erythropoietin, and impaired iron metabolism mediated by inflammatory cytokines and the iron regulatory peptide, hepcidin. Despite marked recent advances in understanding AI, gaps remain, including understanding of the pathogenesis of AI associated with “noninflammatory” or mildly inflammatory diseases, the challenge of excluding iron deficiency anemia in the context of concomitant inflammation, and understanding more precisely the contributory role of hepcidin in the development of AI in human inflammatory diseases

    Varieties of the Highly Dispersible and Hypervariable Tree, Metrosideros Polymorpha, Differ in Response to Mechanical Stress and Light Across a Sharp Ecotone

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    Premise: The drivers of isolation between sympatric populations of long‐lived and highly dispersible conspecific plants are not well understood. In the Hawaiian Islands, the landscape‐dominant tree, Metrosideros polymorpha, displays extraordinary phenotypic differences among sympatric varieties despite high dispersibility of its pollen and seeds, thereby presenting a unique opportunity to investigate how disruptive selection alone can maintain incipient forms. Stenophyllous M. polymorpha var. newellii is a recently evolved tree endemic to the waterways of eastern Hawai\u27i Island that shows striking neutral genetic differentiation from its ancestor, wet‐forest M. polymorpha var. glaberrima, despite sympatry of these forms. We looked for evidence for, and drivers of, differential local adaptation of these varieties across the range of M. polymorpha var. newellii. Methods: For paired populations of these varieties, we compared seedling performance under contrasting light conditions and a strong water current characteristic of the riparian zone. We also conducted a reciprocal transplant experiment and contrasted adult leaf anatomy. Results: Results suggest that the riparian zone is harsh and that selection involving the mechanical stress of rushing water, and secondarily, light, led to significant reciprocal immigrant inviability in adjacent forest and riparian environments. The strongest adaptive divergence between varieties was seen in leaves and seedlings from the site with the sharpest ecotone, coincident with the strongest genetic isolation of M. polymorpha var. newellii observed previously. Conclusions: These findings suggest that disruptive selection across a sharp ecotone contributes to the maintenance of an incipient riparian ecotype from within a continuous population of a long‐lived and highly dispersible tree species

    You Are Welcome Here: The Genesis and Evaluation of a New Employee Orientation Program within the Library

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    Your library may hire new employees throughout the year, but do you prepare them to succeed in your environment? Learn how James Madison University Libraries developed a new employee orientation program designed to meet the needs of new employees, their supervisors, and the entire organization

    A Tentative Detection of a Starspot During Consecutive Transits of an Extrasolar Planet from the Ground: No Evidence of a Double Transiting Planet System Around TrES-1

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    There have been numerous reports of anomalies during transits of the planet TrES-1b. Recently, Rabus and coworkers' analysis of HST observations lead them to claim brightening anomalies during transit might be caused by either a second transiting planet or a cool starspot. Observations of two consecutive transits are presented here from the University of Arizona's 61-inch Kuiper Telescope on May 12 and May 15, 2008 UT. A 5.4 +/- 1.7 mmag (0.54 +/- 0.17%) brightening anomaly was detected during the first half of the transit on May 12 and again in the second half of the transit on May 15th. We conclude that this is a tentative detection of a r greater than or equal to 6 earth radii starspot rotating on the surface of the star. We suggest that all evidence to date suggest TrES-1 has a spotty surface and there is no need to introduce a second transiting planet in this system to explain these anomalies. We are only able to constrain the rotational period of the star to 40.2 +22.9 -14.6 days, due to previous errors in measuring the alignment of the stellar spin axis with the planetary orbital axis. This is consistent with the previously observed P_obs = 33.2 +22.3 -14.3 day period. We note that this technique could be applied to other transiting systems for which starspots exist on the star in the transit path of the planet in order to constrain the rotation rate of the star. (abridged)Comment: 21 pages, 3 tables, 6 figures, Accepted to Ap

    Chimpanzees demonstrate individual differences in social information use

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    Studies of transmission biases in social learning have greatly informed our understanding of how behaviour patterns may diffuse through animal populations, yet within-species inter-individual variation in social information use has received little attention and remains poorly understood. We have addressed this question by examining individual performances across multiple experiments with the same population of primates. We compiled a dataset spanning 16 social learning studies (26 experimental conditions) carried out at the same study site over a 12-year period, incorporating a total of 167 chimpanzees. We applied a binary scoring system to code each participant’s performance in each study according to whether they demonstrated evidence of using social information from conspecifics to solve the experimental task or not (Social Information Score—‘SIS’). Bayesian binomial mixed effects models were then used to estimate the extent to which individual differences influenced SIS, together with any effects of sex, rearing history, age, prior involvement in research and task type on SIS. An estimate of repeatability found that approximately half of the variance in SIS was accounted for by individual identity, indicating that individual differences play a critical role in the social learning behaviour of chimpanzees. According to the model that best fit the data, females were, depending on their rearing history, 15–24% more likely to use social information to solve experimental tasks than males. However, there was no strong evidence of an effect of age or research experience, and pedigree records indicated that SIS was not a strongly heritable trait. Our study offers a novel, transferable method for the study of individual differences in social learning

    Planting Prosperity and Harvesting Health: Trade-offs and Sustainability in the Oregon-Washington Regional Food System

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    This assessment reveals food system sustainability trends in Oregon and Washington, focusing specifically on the producers in both states and the consumers in the Portland- Vancouver region. We began the assessment by asking a group of food system stakeholders from Oregon and Washington to define broadly supported goals for a sustainable food system. They also helped us identify the data necessary to understand trends in the food system. This information can be used in the future to establish benchmarks and to assess future progress toward food system sustainability goals. Framed by stakeholder concerns, this report will assist program and policy decision makers in prioritizing efforts to shape and strengthen the regional food system. This information is also a foundation for building new and unique partnerships among organizations in food system planning

    Prilog poznavanju zdravstvene sluĆŸbe u Novoj Rači i okolici krajem 18. i početkom 19. stoljeća

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    AW and LW were supported by grant ID 40128 from the John Templeton Foundation during the writing of this review.Comparative and evolutionary developmental analyses seek to discover the similarities and differences between humans and non-human species that might illuminate both the evolutionary foundations of our nature that we share with other animals, and the distinctive characteristics that make human development unique. As our closest animal relatives, with whom we last shared common ancestry, non-human primates have been particularly important in this endeavour. Such studies have focused on social learning, traditions, and culture, and have discovered much about the ‘how’ of social learning, concerned with key underlying processes such as imitation and emulation. One of the core discoveries is that the adaptive adjustment of social learning options to different contexts is not unique to human, therefore multiple new strands of research have begun to focus on more subtle questions about when, from whom, and why such learning occurs. Here we review illustrative studies on both human infants and young children and on non-human primates to identify the similarities shared more broadly across the primate order, and the apparent specialisms that distinguish human development. Adaptive biases in social learning discussed include those modulated by task comprehension, experience, conformity to majorities, and the age, skill, proficiency and familiarity of potential alternative cultural models.PostprintPeer reviewe
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