5,008 research outputs found

    The James Webb Space Telescope: Mission Overview and Status

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    The James Webb Space Telescope (JWST) is the scientific successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 m2 aperture (6 m class) telescope that will achieve diffraction limited angular resolution at a wavelength of 2 um. The science instrument payload includes four passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronography, as well as multi-object and integral-field spectroscopy over the 0.6 < < 5.0 m spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronography, and integral-field spectroscopy over the 5.0 < < 29 m spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete. Construction, integration and verification testing is underway in all areas of the program. The JWST is on schedule for launch during 2021

    The (32)S/(33)S abundance as a function of galactocentric radius in the Milky Way

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    Astration of heavy elements by the stars of the Milky Way forms a fossil record which may preserve spacial distribution of the mass function for the stars in the galaxy. Sulfur is among the last common element for which the relative abundance of its various isotopes have yet to be completely measured within our galaxy. Explosive oxygen burning in massive stars is thought to be the process which dominates sulfur production within stars. There models predict that the various isotopes (S-32, S-33, S-34) are formed in relative abundance which depend strongly upon the mass of the parent star. This relative abundance is thought to be unaffected by subsequent stellar procesing since all important sinks of sulfur destroy it without regard for isotopic form. Hence the spacial variation of the mass function (MF) can be studied by measuring the abundance variation of sulfur isotopes in the galaxy provided that the product yields for these isotopes are known accurately as a function of stellar mass

    The James Webb Space Telescope: Mission Overview and Status

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    The James Webb Space Telescope (JWST) is the infrared successor to the Hubble Space Telescope. It is a cryogenic infrared space observatory with a 25 sq. m aperture (6 m telescope yielding diffraction limited angular resolution at a wavelength of 2 micron. The science instrument payload includes three passively cooled near-infrared instruments providing broad- and narrow-band imagery, coronagraphy, as well as multi object and integral-field spectroscopy over the 0.6 < 0 < 5.0 micron spectrum. An actively cooled mid-infrared instrument provides broad-band imagery, coronagraphy, and integral-field spectroscopy over the 5.0 < 0 < 29 micron spectrum. The JWST is being developed by NASA, in partnership with the European and Canadian Space Agencies, as a general user facility with science observations to be proposed by the international astronomical community in a manner similar to the Hubble Space Telescope. Technology development and mission design are complete, and construction is underway in all areas of the program. The JWST is on schedule to reach launch readiness during 2014

    Cualidades corporativas en el derecho y la sociedad: un caso de los Estados Unidos

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    Neoliberalism compresses state and non-state powers together in ways that pose fresh interpretive challenges for anthropologists and sociolegal scholars interested in the social and cultural significance of law. In this article, I develop a “case study” around a recent opinion of the United States Supreme Court in which these are among the issues. I examine Federal Elections Commission versus Citizens United —a case that involved the rights of corporations to spend money on federal electoral campaigns. The outcome was highly controversial in the United States, since it removed longstanding restrictions on corporate spending in the political sphere. From an ethnographic standpoint, though, the significance of the case may be less in what it allows corporations to say and do in the electoral context, than in the ways particular qualities of sociality claimed (by the Court) to be inherent in corporations are valorized and prioritized. I suggest that the protean nature of corporate qualities as defined by the Court points to a potential significance of the case to everyday life that extends to the meaning of the very distinction between law and society.La sociedad neoliberal engloba tanto poderes estatales como no estatales, de modo tal que plantea nuevos retos interpretativos a los antropólogos y sociólogos del derecho interesados en la significación social y cultural del derecho. Desarrollo aquí un “estudio de caso” en torno a un dictamen reciente del Tribunal Supremo de los Estados Unidos en el cual esos aspectos figuran entre los temas que contempla. Examino el asunto Comisión de Elecciones Federales contra Ciudadanos Unidos [Citizens United] —un caso que implicaba el derecho de las empresas a invertir dinero en campañas electorales federales. El resultado fue altamente polémico en Estados Unidos, ya que eliminaba antiguas restricciones relativas a la inversión empresarial en la esfera política. Desde un punto de vista etnográfico, sin embargo, la relevancia del dictamen puede estar menos en lo que permite a las corporaciones decir y hacer en el contexto electoral que en el modo en que cualidades peculiares de carácter social, pretendidamente (por el Tribunal) inherentes a las empresas, son valoradas y priorizadas. Sugiero que la multiforme naturaleza de las cualidades de las empresas, tal como las define el Tribunal, apunta al significado potencial del caso para la vida cotidiana que alcanza al sentido de la propia diferenciación entre derecho y sociedad

    Drug resistance mediating Plasmodium falciparum polymorphisms and clinical presentations of parasitaemic children in Uganda.

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    BackgroundPlasmodium falciparum genetic polymorphisms that mediate altered drug sensitivity may impact upon virulence. In a cross-sectional study, Ugandan children with infections mutant at pfcrt K76T, pfmdr1 N86Y, or pfmdr1 D1246Y had about one-fourth the odds of symptomatic malaria compared to those with infections with wild type (WT) sequences. However, results may have been confounded by greater likelihood in those with symptomatic disease of higher density mixed infections and/or recent prior treatment that selected for WT alleles.MethodsPolymorphisms in samples from paired episodes of asymptomatic and symptomatic parasitaemia in 114 subjects aged 4-11 years were followed longitudinally in Tororo District, Uganda. Paired episodes occurred within 3-12 months of each other and had no treatment for malaria in the prior 60 days. The prevalence of WT, mixed, and mutant alleles was determined using multiplex ligase detection reaction-fluorescent microsphere assays.ResultsConsidering paired episodes in the same subject, the odds of symptomatic malaria were lower for infections with mutant compared to WT or mixed sequence at N86Y (OR 0.26, 95% CI 0.09-0.79, p = 0.018), but not K76T or D1246Y. However, symptomatic episodes (which had higher densities) were more likely than asymptomatic to be mixed (for N86Y OR 2.0, 95% CI 1.04-4.0, p = 0.036). Excluding mixed infections, the odds of symptomatic malaria were lower for infections with mutant compared to WT sequence at N86Y (OR 0.33, 95% CI 0.11-0.98, p = 0.046), but not the other alleles. However, if mixed genotypes were grouped with mutants in this analysis or assuming that mixed infections consisted of 50% WT and 50% mutant genotypes, the odds of symptomatic infection did not differ between infections that were mutant or WT at the studied alleles.ConclusionsAlthough infections with only the mutant pfmdr1 86Y genotype were associated with symptomatic infection, this association could primarily be explained by greater parasite densities and therefore greater prevalence of mixed infections in symptomatic children. These results indicate limited association between the tested polymorphisms and risk of symptomatic disease and highlight the value of longitudinal studies for assessing associations between parasite factors and clinical outcomes

    Carbon dioxide emissions from diesel and compressed natural gas buses during acceleration

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    Motor vehicle emission factors are generally derived from driving tests mimicking steady state conditions or transient drive cycles. However, neither of these test conditions completely represents real world driving conditions. In particular, they fail to determine emissions generated during the accelerating phase – a condition in which urban buses spend much of their time. In this study we analyse and compare the results of time-dependant emission measurements conducted on diesel and compressed natural gas (CNG) buses during an urban driving cycle on a chassis dynamometer and we derive power-law expressions relating carbon dioxide (CO2) emission factors to the instantaneous speed while accelerating from rest. Emissions during acceleration are compared with that during steady speed operation. These results have important implications for emission modelling particularly under congested traffic conditions
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