704 research outputs found
RC rate generator for slow speed measurement Patent
Device utilizing RC rate generators for continuous slow speed measuremen
Passive, Low Cost Neutron Detectors for Neutron Diagnostics at the National Ignition Facility
Experimental validation of neutron fluence models of fusion events at the National Ignition Facility is necessary to predict radiation damage to measurement electronics. Due to programmatic and facility limitations, traditional neutron measurement techniques are not well suited for this application. Notably, a low cost and passive measurement technique that provides a permanent record is preferred. A detector was designed using gadolinium oxide contained within an aluminum reservoir. The reservoir is secured by a thin layer of Mylar and x-ray film, and vacuum sealed in a light tight package. In the presence of a thermal neutron flux, the gadolinium atoms absorb incident neutrons and partially de-excite by conversion electron emission. The conversion electrons exit the gadolinium oxide layer, penetrate the Mylar, and expose the x-ray film. After developing the film, the film exposure is quantified and directly related to the neutron fluence. The configuration was sensitive to thermal neutron fluences between 1.43 x 107 and 1.43 x 109 n/cm2, and could distinguish between fluences differing by more than a tenth of a decade
ECONOMIC SURPLUS AND THE DISTRIBUTIONAL CONSEQUENCES OF DEREGULATING TOBACCO PRODUCTION
Reservations on technical and theoretical grounds in the use of the consumer surplus approach to measure benefits of government programs have often appeared in the literature. Therefore, this paper uses an alternative approach in a case study to estimate the annual economic surplus created in South Carolina from deregulating tobacco production. Impacts of deregulation on cropping patterns and income on representative tobacco farms, and distribution of benefits in the economy are examined. Results of this study indicate that deregulation stimulates the economy and would increase the net value added by $5.8 million in the long run.Agricultural and Food Policy,
HAZMAT VI: The Evolution of Extreme Ultraviolet Radiation Emitted from Early M Star
Quantifying the evolution of stellar extreme ultraviolet (EUV, 100 -- 1000
) emission is critical for assessing the evolution of
planetary atmospheres and the habitability of M dwarf systems. Previous studies
from the HAbitable Zones and M dwarf Activity across Time (HAZMAT) program
showed the far- and near-UV (FUV, NUV) emission from M stars at various stages
of a stellar lifetime through photometric measurements from the Galaxy
Evolution Explorer (GALEX). The results revealed increased levels of
short-wavelength emission that remain elevated for hundreds of millions of
years. The trend for EUV flux as a function of age could not be determined
empirically because absorption by the interstellar medium prevents access to
the EUV wavelengths for the vast majority of stars. In this paper, we model the
evolution of EUV flux from early M stars to address this observational gap. We
present synthetic spectra spanning EUV to infrared wavelengths of 0.4
0.05 M stars at five distinct ages between 10 and 5000 Myr, computed
with the PHOENIX atmosphere code and guided by the GALEX photometry. We model a
range of EUV fluxes spanning two orders of magnitude, consistent with the
observed spread in X-ray, FUV, and NUV flux at each epoch. Our results show
that the stellar EUV emission from young M stars is 100 times stronger than
field age M stars, and decreases as t after remaining constant for a few
hundred million years. This decline stems from changes in the chromospheric
temperature structure, which steadily shifts outward with time. Our models
reconstruct the full spectrally and temporally resolved history of an M star's
UV radiation, including the unobservable EUV radiation, which drives planetary
atmospheric escape, directly impacting a planet's potential for habitability.Comment: 23 pages, 15 figures, accepted to Ap
Clinical and molecular genetic features of pulmonary hypertension in patients with hereditary hemorrhagic telangiectasia
BACKGROUND: Most patients with familial primary pulmonary hypertension have defects in the gene for bone morphogenetic protein receptor II (BMPR2), a member of the transforming growth factor beta (TGF-beta) superfamily of receptors. Because patients with hereditary hemorrhagic telangiectasia may have lung disease that is indistinguishable from primary pulmonary hypertension, we investigated the genetic basis of lung disease in these patients.
METHODS: We evaluated members of five kindreds plus one individual patient with hereditary hemorrhagic telangiectasia and identified 10 cases of pulmonary hypertension. In the two largest families, we used microsatellite markers to test for linkage to genes encoding TGF-beta-receptor proteins, including endoglin and activin-receptor-like kinase 1 (ALK1), and BMPR2. In subjects with hereditary hemorrhagic telangiectasia and pulmonary hypertension, we also scanned ALK1 and BMPR2 for mutations.
RESULTS: We identified suggestive linkage of pulmonary hypertension with hereditary hemorrhagic telangiectasia on chromosome 12q13, a region that includes ALK1. We identified amino acid changes in activin-receptor-like kinase 1 that were inherited in subjects who had a disorder with clinical and histologic features indistinguishable from those of primary pulmonary hypertension. Immunohistochemical analysis in four subjects and one control showed pulmonary vascular endothelial expression of activin-receptor-like kinase 1 in normal and diseased pulmonary arteries.
CONCLUSIONS: Pulmonary hypertension in association with hereditary hemorrhagic telangiectasia can involve mutations in ALK1. These mutations are associated with diverse effects, including the vascular dilatation characteristic of hereditary hemorrhagic telangiectasia and the occlusion of small pulmonary arteries that is typical of primary pulmonary hypertension
This New Ocean: A History of Project Mercury
When Congress created the National Aeronautics and Space Administration (NASA) in 1958, it charged NASA with the responsibility "to contribute materially to . . . the expansion of human knowledge of phenomena in the atmosphere and space" and "provide for the widest practicable and appropriate dissemination of information concerning its activities and the results thereof." NASA wisely interpreted this mandate to include responsibility for documenting the epochal progress of which it is the focus. The result has been the development of a historical program by NASA as unprecedented as the task of extending man's mobility beyond his planet. This volume is not only NASA's accounting of its obligation to disseminate information to our current generation of Americans. It also fulfills, as do all of NASA's future-oriented scientific-technological activities, the further obligation to document the present as the heritage of the future. The wide-ranging NASA history program includes chronicles of day-to-day space activities; specialized studies of particular fields within space science and technology; accounts of NASA's efforts in organization and management, where its innovations, while less known to the public than its more spectacular space shots, have also been of great significance; narratives of the growth and expansion of the space centers throughout the country, which represent in microcosm many aspects of NASA's total effort; program histories, tracing the successes- and failures- of the various projects that mark man's progress into the Space Age; and a history of NASA itself, incorporating in general terms the major problems and challenges, and the responses thereto, of our entire civilian space effort. The volume presented here is a program history, the first in a series telling of NASA's pioneering steps into the Space Age. It deals with the first American manned-spaceflight program: Project Mercury. Although some academicians might protest that this is "official" history, it is official only in the fact that it has been prepared and published with the support and cooperation of NASA. It is not "official" history in the sense of presenting a point of view supposedly that of NASA officialdom-if anyone could determine what the "point of view" of such a complex organism might be. Certainly, the authors were allowed to pursue their task with the fullest freedom and in accordance with the highest scholarly standards of the history profession
Forestry Bulletin No. 18: Geography of the Southern Forest Region
The Southern Forest Region, as here discussed, comprises the area east of the Texas and Oklahoma prairies and south of the Missouri, Ohio, and Potomac rivers, plus an extension along the Atlantic coast to central New Jersey.https://scholarworks.sfasu.edu/forestrybulletins/1014/thumbnail.jp
Comparing the Performance of a 2009 IECC Code-Compliant House Using Code-Compliant Residential Simulation Programs
The Residential Energy Services Network (RESNET) is an independent, non-profit organization that helps homeowners reduce energy costs by providing energy efficiency strategies. RESNET performs certification of code-compliance software using a test suite (RESNET 2007). Acceptance variations in the RESNET tests include a provision of minimum and maximum limits of variation on a case-by-case basis or a sensitivity basis. Results are provided for either heating or cooling loads or heating and cooling energy consumption (RESNET 2007). However, significant differences exist in the results obtained from these software programs on performing compliance with the performance path specified in the International Energy Conservation Code (IECC).
This paper is a continuation of an earlier attempt to explore these differences and find out the cause of such discrepancies (Liu et al., 2010). This paper also determines a bandwidth within which variation in results from the different software programs that can be deemed to be acceptable. The paper provides a comparison of four code-compliant software, three of which are RESNET certified. The comparison is performed for three climate zones in Texas. For most cases of the comparison, the results from the three RESNET certified software are within 5% of each other. However, variation in results from the three RESNET certified software programs exceeds 5% in certain cases of ceiling R-values in all climate zones and in certain cases of window-to-wall area ratios in Climate Zone-4
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