559 research outputs found

    Orbital transfer vehicle oxygen turbopump technology. Volume 1: Design, fabrication, and hydrostatic bearing testing

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    The design, fabrication, and initial testing of a rocket engine turbopump (TPA) for the delivery of high pressure liquid oxygen using hot oxygen for the turbine drive fluid are described. This TPA is basic to the dual expander engine which uses both oxygen and hydrogen as working fluids. Separate tasks addressed the key issue of materials for this TPA. All materials selections emphasized compatibility with hot oxygen. The OX TPA design uses a two-stage centrifugal pump driven by a single-stage axial turbine on a common shaft. The design includes ports for three shaft displacement/speed sensors, various temperature measurements, and accelerometers

    Biomechanics of predator–prey arms race in lion, zebra, cheetah and impala

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    The fastest and most manoeuvrable terrestrial animals are found in savannah habitats, where predators chase and capture running prey. Hunt outcome and success rate are critical to survival, so both predator and prey should evolve to be faster and/or more manoeuvrable. Here we compare locomotor characteristics in two pursuit predator–prey pairs, lion–zebra and cheetah–impala, in their natural savannah habitat in Botswana. We show that although cheetahs and impalas were universally more athletic than lions and zebras in terms of speed, acceleration and turning, within each predator–prey pair, the predators had 20% higher muscle fibre power than prey, 37% greater acceleration and 72% greater deceleration capacity than their prey. We simulated hunt dynamics with these data and showed that hunts at lower speeds enable prey to use their maximum manoeuvring capacity and favour prey survival, and that the predator needs to be more athletic than its prey to sustain a viable success rate

    A non-linear optimal estimation inverse method for radio occultation measurements of temperature, humidity and surface pressure

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    An optimal estimation inverse method is presented which can be used to retrieve simultaneously vertical profiles of temperature and specific humidity, in addition to surface pressure, from satellite-to-satellite radio occultation observations of the Earth's atmosphere. The method is a non-linear, maximum {\it a posteriori} technique which can accommodate most aspects of the real radio occultation problem and is found to be stable and to converge rapidly in most cases. The optimal estimation inverse method has two distinct advantages over the analytic inverse method in that it accounts for some of the effects of horizontal gradients and is able to retrieve optimally temperature and humidity simultaneously from the observations. It is also able to account for observation noise and other sources of error. Combined, these advantages ensure a realistic retrieval of atmospheric quantities. A complete error analysis emerges naturally from the optimal estimation theory, allowing a full characterisation of the solution. Using this analysis a quality control scheme is implemented which allows anomalous retrieval conditions to be recognised and removed, thus preventing gross retrieval errors. The inverse method presented in this paper has been implemented for bending angle measurements derived from GPS/MET radio occultation observations of the Earth. Preliminary results from simulated data suggest that these observations have the potential to improve NWP model analyses significantly throughout their vertical range.Comment: 18 (jgr journal) pages, 7 figure

    Considering methodological options for reviews of theory: illustrated by a review of theories linking income and health

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    Background: Review of theory is an area of growing methodological advancement. Theoretical reviews are particularly useful where the literature is complex, multi-discipline, or contested. It has been suggested that adopting methods from systematic reviews may help address these challenges. However, the methodological approaches to reviews of theory, including the degree to which systematic review methods can be incorporated, have received little discussion in the literature. We recently employed systematic review methods in a review of theories about the causal relationship between income and health. Methods: This article discusses some of the methodological issues we considered in developing the review and offers lessons learnt from our experiences. It examines the stages of a systematic review in relation to how they could be adapted for a review of theory. The issues arising and the approaches taken in the review of theories in income and health are considered, drawing on the approaches of other reviews of theory. Results: Different approaches to searching were required, including electronic and manual searches, and electronic citation tracking to follow the development of theories. Determining inclusion criteria was an iterative process to ensure that inclusion criteria were specific enough to make the review practical and focused, but not so narrow that key literature was excluded. Involving subject specialists was valuable in the literature searches to ensure principal papers were identified and during the inductive approaches used in synthesis of theories to provide detailed understanding of how theories related to another. Reviews of theory are likely to involve iterations and inductive processes throughout, and some of the concepts and techniques that have been developed for qualitative evidence synthesis can be usefully translated to theoretical reviews of this kind. Conclusions: It may be useful at the outset of a review of theory to consider whether the key aim of the review is to scope out theories relating to a particular issue; to conduct in-depth analysis of key theoretical works with the aim of developing new, overarching theories and interpretations; or to combine both these processes in the review. This can help decide the most appropriate methodological approach to take at particular stages of the review

    Ground states of a one-dimensional lattice-gas model with an infinite range nonconvex interaction. A numerical study

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    We consider a lattice-gas model with an infinite range pairwise noncovex interaction. It might be relevant, for example, for adsorption of alkaline elements on W(112) and Mo(112). We study a competition between the effective dipole-dipole and indirect interactions. The resulting ground state phase diagrams are analysed (numerically) in detail. We have found that for some model parameters the phase diagrams contain a region dominated by several phases only with periods up to nine lattice constants. The remaining phase diagrams reveal a complex structure of usually long periodic phases. We also discuss a possible role of surace states in phase transitions.Comment: 16 pages, 5 Postscript figures; Physical Review B15 (15 August 1996), in pres

    Resonant Structure of τ3ππ0ντ\tau\to 3\pi\pi^{0}\nu_{\tau} and τωπντ\tau\to \omega\pi\nu_{\tau} Decays

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    The resonant structure of the four pion final state in the decay τ3ππ0ντ\tau \to 3\pi\pi^0\nu_\tau is analyzed using 4.27 million τ+τ\tau^+\tau^- pairs collected by the CLEO II experiment. We search for second class currents in the decay τωπντ\tau \to \omega\pi\nu_\tau using spin-parity analysis and establish an upper limit on the non-vector current contribution. The mass and width of the ρ\rho' resonance are extracted from a fit to the τωπντ\tau \to \omega\pi\nu_\tau spectral function. A partial wave analysis of the resonant structure of the τ3ππ0ντ\tau \to 3\pi\pi^0\nu_\tau decay is performed; the spectral decomposition of the four pion system is dominated by the ωπ\omega\pi and a1πa_1 \pi final states.Comment: 34 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Socioeconomic differentials in the immediate mortality effects of the national Irish smoking ban

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    This article has been made available through the Brunel Open Access Publishing Fund.Background: Consistent evidence has demonstrated that smoking ban policies save lives, but impacts on health inequalities are uncertain as few studies have assessed post-ban effects by socioeconomic status (SES) and findings have been inconsistent. The aim of this study was to assess the effects of the national Irish smoking ban on ischemic heart disease (IHD), stroke, and chronic obstructive pulmonary disease (COPD) mortality by discrete and composite SES indicators to determine impacts on inequalities. Methods: Census data were used to assign frequencies of structural and material SES indicators to 34 local authorities across Ireland with a 2000–2010 study period. Discrete indicators were jointly analysed through principal component analysis to generate a composite index, with sensitivity analyses conducted by varying the included indicators. Poisson regression with interrupted time-series analysis was conducted to examine monthly age and gender-standardised mortality rates in the Irish population, ages ≥35 years, stratified by tertiles of SES indicators. All models were adjusted for time trend, season, influenza, and smoking prevalence. Results: Post-ban mortality reductions by structural SES indicators were concentrated in the most deprived tertile for all causes of death, while reductions by material SES indicators were more equitable across SES tertiles. The composite indices mirrored the results of the discrete indicators, demonstrating that post-ban mortality decreases were either greater or similar in the most deprived when compared to the least deprived for all causes of death. Conclusions: Overall findings indicated that the national Irish smoking ban reduced inequalities in smoking-related mortality. Due to the higher rates of smoking-related mortality in the most deprived group, even equitable reductions across SES tertiles resulted in decreases in inequalities. The choice of SES indicator was influential in the measurement of effects, underscoring that a differentiated analytical approach aided in understanding the complexities in which structural and material factors influence mortality

    Hadronic Structure in the Decay τππ0ντ\tau^{-}\to \pi^{-}\pi^{0}\nu_{\tau}

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    We report on a study of the invariant mass spectrum of the hadronic system in the decay tau- -> pi- pi0 nu_tau. This study was performed with data obtained with the CLEO II detector operating at the CESR e+ e- collider. We present fits to phenomenological models in which resonance parameters associated with the rho(770) and rho(1450) mesons are determined. The pi- pi0 spectral function inferred from the invariant mass spectrum is compared with data on e+ e- -> pi+ pi- as a test of the Conserved Vector Current theorem. We also discuss the implications of our data with regard to estimates of the hadronic contribution to the muon anomalous magnetic moment.Comment: 39 pages postscript, also available through http://w4.lns.cornell.edu/public/CLN

    Uncovered diversity of a predominantly andean butterfly clade in the brazilian atlantic forest : a revision of the genus praepedaliodes forster (Lepidoptera: Nymphalidae, Satyrinae, Satyrini)

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    The genus Praepedaliodes Forster, 1964, the only representative of the mega-diverse mostly Andean Pedaliodes complex lineage in the Brazilian Atlantic Forest, is revised. Prior to this study, four species were known, P. phanias (Hewitson, 1862), P. granulata (Butler, 1868), P. amussis (Thieme, 1905) and P. exul (Thieme, 1905). Here, a further six are described, all from SE Brazil, expanding to 10 the number of species in this genus. Lectotypes are designated for P. phanias, P. granulata and P. amussis. The genus is most diverse in the Serra da Mantiqueira (São Paulo, Rio de Janeiro, Minas Gerais) and in the Serra Geral (Paraná, Santa Catarina) with seven species occurring in both ranges. Praepedaliodes phanias is the most widespread species and the only one found in the western part of the Atlantic Forest; only this species and P. duartei Dias, Dolibaina & Pyrcz n. sp. occurring to near sea level. Other species, P. zaccae Dolibaina, Dias & Pyrcz n. sp., P. francinii Freitas & Pyrcz n. sp., P. sequeirae Pyrcz, Dias & Dolbaina n. sp., P. landryi Pyrcz & Freitas n. sp. and P. pawlaki Pyrcz & Boyer n. sp. are strictly montane and the highest species richness is reached at 1400–1800 m. One species, P. sequeirae n. sp., is a narrow endemic found only at timberline in the Agulhas Negras massif above 2300 m. Immature stages are described for two species, P. phanias and P. landryi n. sp. Molecular data (barcode region of cytochrome oxidase, subunit I) and adult morphology, including male and female genitalia, support the genus as monophyletic, belonging to a predominantly Andean clade of the Pedaliodes Butler, 1867 complex. Morphological evidences, in particular female genitalia comparative analysis, indicate the genera Physcopedaliodes Forster, 1964 and Panyapedaliodes Forster, 1964 as possibly the closest relatives to Praepedaliodes. Molecular data are inconclusive in this respect472211255CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP302585/2011-7, 303834/2015-3; 563332/2010-7; 41143/2009-6; 150542/2013-5; 308247/2013-2; 304639/2014-1Não tem2016/15873-8; 2011/50225-3; 2013/50297-0We would like to express our gratitude the following persons who contributed at different stages in the elaboration of this paper: Alfred Moser (Porto Alegre), Ronaldo Francini (UNISANTOS) and André Tacioli, Junia Y. O. Carreira, Jessie P. Santos and Ana K. Silva (Unicamp) for logistical help in the field, comparison material and hosting Tamara M. C. Aguiar spread most of the adult DNA vouchers and the old material collected by K. S. Brown Jr. The following people helped by sending material and information: Roberto R. Greve (Foz do Iguaçu), Richard Raby (Serra da Bocaina), Augusto H. B. Rosa (Mantiqueira region), Geanne C. N. Pereira (Serra do Cipó) and Keith S. Brown Jr. (several places in SE Brazil). The authors also thank the ICMBio for the permits (#10438-1, #26712-4 and #10802-9), the CNPq by aproving our Scientific Expedition (portaria N° 240, de 11 de março de 2014) and all managers of the Conservation Unities visited during the development of the present study, in special Waldomiro P. Lopes (Parque Nacional do Caparaó), Léo Nascimento (Parque Nacional do Itatiaia), Mara P. Pais (Parque Nacional da Serra da Bocaina), Ingo Grantsau (Paranapiacaba) and Cecilia Cronemberger (Parque Nacional da Serra dos Órgãos). EPB thanks Fundação de Amparo à Pesquisa no Estado de São Paulo (FAPESP) for a Post-doc fellowship (2016/15873-8). AVLF thanks the CNPq (fellowships 302585/2011-7, 303834/2015-3 and SISBIOTABrasil/CNPq - 563332/2010-7), the National Science Foundation (DEB-1256742), the “Rede Nacional de Identificação Molecular da Biodiversidade - BR-BoL” (MCT/CNPq/FNDCT 50/2010) and the BIOTA-FAPESP Program (2011/50225-3 and 2013/50297-0). Kim Garwood kindly provided the photographs of two species of Praepedaliodes in their natural habitat. Keith Willmott read the manuscript and added several valuable suggestions. Carlos Prieto provided the photograph of the syntype of Praepedaliodes amussis. TWP field work in SE Brazil was supported by MZ/IZ/UJ internal grants. FMSD, DRD, OHHM and MMC thank Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES, Edital 15/2014 CAPES/EMBRAPA) and Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq, 141143/2009-6, 150542/2013-5, 308247/2013-2, 304639/2014-1), for the fellowships granted to the author
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