4,629 research outputs found

    Performance evaluation of a kinesthetic-tactual display

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    Simulator studies demonstrated the feasibility of using kinesthetic-tactual (KT) displays for providing collective and cyclic command information, and suggested that KT displays may increase pilot workload capability. A dual-axis laboratory tracking task suggested that beyond reduction in visual scanning, there may be additional sensory or cognitive benefits to the use of multiple sensory modalities. Single-axis laboratory tracking tasks revealed performance with a quickened KT display to be equivalent to performance with a quickened visual display for a low frequency sum-of-sinewaves input. In contrast, an unquickened KT display was inferior to an unquickened visual display. Full scale simulator studies and/or inflight testing are recommended to determine the generality of these results

    Does Venture Capital Require an Active Stock Market?

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    The United States has both an active venture capital industry and well-developed stock markets. Japan and Germany have neither. We argue here that this is no accident – that venture capital can flourish especially – and perhaps only – if the venture capitalist can exit from a successful portfolio company through an initial public offering (IPO), which requires an active stock market. Understanding the link between the stock market and the venture capital market requires understanding the contractual arrangements between entrepreneurs and venture capital providers especially the importance of exit by venture capitalists and the opportunity, present only if IPO exit is possible, for the venture capitalist and the entrepreneur to enter into an implicit contract over control, in which a successful entrepreneur can reacquire control from the venture capitalist by using an IPO as the means of exit

    Building the field of health policy and systems research: framing the questions.

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    In the first of a series of articles addressing the current challenges and opportunities for the development of Health Policy & Systems Research (HPSR), Kabir Sheikh and colleagues lay out the main questions vexing the field

    Quark mass density- and temperature- dependent model for strange quark matter

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    It is found that the radius of a stable strangelet decreases as the temperature increases in a quark mass density-dependent model. To overcome this difficulty, we extend this model to a quark mass density- and temperature- dependent model in which the vacuum energy density at zero baryon density limit B depends on temperature. An ansatz is introduced and the regions for the best choice of the parameters are studied.Comment: 5 pages, 4 figure

    Biologia reprodutiva da surucucu Lachesis muta (Serpentes: Viperidae) da Floresta Atlântica brasileira

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    The Neotropical genus Lachesis Daudin, 1803 includes snakes restricted to the humid forests of Central and South America. The species L. muta is the most widely dispersed, occurring throughout the Amazon rainforest, and with an isolated population in the Atlantic Forest, from the north of the state of Ceará to the south of the state of Rio de Janeiro, Brazil. We present information about the reproductive biology of L. muta from a large series of samples gathered in southern Bahia. Mature males L. muta are larger than females. Degree of sexual size dimorphism (SSD) is 0.16. Vitellogenic follicles and eggs are not distributed equally throughout the year. Clutch size was 3–14 oviductal eggs and was positively correlated with female SVL. Testes volume and ductus deferens diameter in mature individuals did not vary significantly throughout the year. The reproductive pattern of L. muta differs from that of the phylogenetically related genera because L. muta is oviparous, and has a discontinuous cycle and reproductive synchrony between the sexes.O gênero Neotropical Lachesis Daudin, 1803 inclui serpentes restritas às florestas úmidas da América do Sul e Central. A espécie Lachesis muta é mais amplamente distribuída, ocorrendo em toda a Floresta Amazônica e com uma população isolada na Mata Atlântica, desde o norte do estado do Ceará, ao sul do estado do Rio de Janeiro, Brasil. Apresentamos informações sobre a biologia reprodutiva de L. muta a partir da análise de uma grande série de amostras recolhidas no sul da Bahia. Os machos maduros de L. muta foram maiores que as fêmeas. O grau de dimorfismo sexual (SSD) foi 0,16. Folículos vitelogênicos e ovos não foram distribuídos homogeneamente ao longo do ano. O tamanho da ninhada foi 3–14 ovos e positivamente correlacionado com o CRC das fêmeas. O volume testicular e o diâmetro dos ductos deferentes nos indivíduos maduros não apresentaram variação significativa ao longo do ano. O padrão reprodutivo de L. muta difere daquele de gêneros filogeneticamente relacionados, pois essa espécie é ovípara, tem ciclo descontínuo e sincronia reprodutiva entre os sexos

    Very Small Strangelets

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    We study the stability of small strangelets by employing a simple model of strange matter as a gas of non-interacting fermions confined in a bag. We solve the Dirac equation and populate the energy levels of the bag one quark at a time. Our results show that for system parameters such that strange matter is unbound in bulk, there may still exist strangelets with A<100A<100 that are stable and/or metastable. The lifetime of these strangelets may be too small to detect in current accelerator experiments, however.Comment: 13 pages, MIT CTP#217

    The menopause transition in women living with HIV: current evidence and future avenues of research

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    As the life expectancy of people living with HIV improves as a result of antiretroviral therapy, increasing numbers of women living with HIV (WLHIV) are now reaching menopausal age. The menopause transition in WLHIV remains a relatively overlooked area in clinical HIV research. Whilst there is some evidence to suggest that WLHIV experience menopause at an earlier age and that they have more menopausal symptoms, there is no clear consensus in the literature around an impact of HIV infection on either timing or symptomatology of the menopause. Data are also conflicting on whether HIV-related factors such as HIV viral load and CD4 cell count have an impact on the menopause. Furthermore, menopausal symptoms in WLHIV are known to go under-recognised by both healthcare providers and women themselves. There is likely to be a burden of unmet health needs among WLHIV transitioning through the menopause, with significant gaps in the evidence base for their care. With this in mind, we have developed the PRIME study (Positive Transitions Through the Menopause). This mixed-methods observational study will explore, for the first time in the UK, the impact of the menopause on the health and wellbeing of 1500 ethnically diverse WLHIV. In establishing a cohort of women in their midlife and following them up longitudinally, we hope to develop a nuanced understanding of the gendered aspects of ageing and HIV, informing the provision of appropriate services for WLHIV to ensure that they are supported in maintaining optimal health and wellbeing as they get older

    Shorewards Upslope of the Layer of Minimum Oxygen Off Bombay: Its Influence on Marine Biology, Especially Fisheries

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    Shorewards Upslope of the Layer of Minimum Oxygen Off Bombay: Its Influence on Marine Biology, Especially Fisherie

    The EU and Asia within an evolving global order: what is Europe? Where is Asia?

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    The papers in this special edition are a very small selection from those presented at the EU-NESCA (Network of European Studies Centres in Asia) conference on "the EU and East Asia within an Evolving Global Order: Ideas, Actors and Processes" in November 2008 in Brussels. The conference was the culmination of three years of research activity involving workshops and conferences bringing together scholars from both regions primarily to discuss relations between Europe and Asia, perceptions of Europe in Asia, and the relationship between the European regional project and emerging regional forms in Asia. But although this was the last of the three major conferences organised by the consortium, it in many ways represented a starting point rather than the end; an opportunity to reflect on the conclusions of the first phase of collaboration and point towards new and continuing research agendas for the future
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