2,051 research outputs found
Obstruction theory on 8-manifolds
This note gives a uniform, self-contained, and fairly direct approach to a
variety of obstruction-theoretic problems on 8-manifolds. We give necessary and
sufficient cohomological critera for the existence of almost complex and almost
quaternionic structures on the tangent bundle and for the reduction of the
structure group to U(3) by the homomorphism U(3) --> O(8) given by the Lie
algebra representation of PU(3).Comment: 19 page
Synergism of He-3 acquisition with lunar base evolution
Researchers have discovered that the lunar surface contains a valuable fusion fuel element that is relatively scarce on Earth. This element, He-3, originates from the solar wind that has bombarded the surface of the Moon over geologic time. Mining operations to recover this resource would allow the by-product acquisition of hydrogen, water, carbon dioxide, carbon monoxide, methane, and nitrogen from the lunar surface with relatively minimal additional resource investment when compared to the costs to supply these resources from Earth. Two configurations for the He-3 mining system are discussed, and the impacts of these mining operations on a projected lunar base scenario are assessed. We conclude that the acquisition of He-3 is feasible with minimal advances in current state-of-the-art technologies and could support a terrestrial nuclear fusion power economy with the lowest hazard risk of any nuclear reaction known. Also, the availability of the by-products of He-3 acquisition from the Moon could significantly reduce the operational requirements of a lunar base and increase the commercialization potential of the base through consumable resupply of the lunar base itself, other components of the space infrastructure, and other space missions
Synergism of He-3 acquisition with lunar base evolution
It is shown how acquisition of He-3 affects Lunar Base development and operation. A four phase evolutionary Lunar Base scenario is summarized with initial equipment mass and resupply requirements. Requirements for various He-3 mining operations are shown and available by-products are identified. Impacts of mining He-3 on Lunar Base development include increases in equipment masses to be delivered to the lunar surface and a reduction of Lunar Base resupply based on availability of He-3 acquisition by-products. It is concluded that the acquisition of this valuable fusion fuel element greatly enhances the commercial potential of a Lunar Base
Effect of closing facilities on electroconvulsive therapy use in Glasgow
<p>Objectives: To assess the effect of closure of electroconvulsive therapy (ECT) centers on ECT use. Electroconvulsive therapy remains a recommended and effective treatment for mental disorders. Declining rates
of ECT use in the United Kingdom have been observed over the last 20 years with anecdotal observations that use has declined as the result of centralization of provision. In Glasgow, there have been site closures in the north with no such rationing taking place in the south.</p>
<p>Methods: A naturalistic retrospective survey of the number of ECT
courses commenced each year in Glasgow, with a comparison made between the north and the south of the city. Data were available from 1996 to 2008.</p>
<p>Results: Our analysis showed no change in the mean number of ECT courses commenced in southern AQ2 Glasgow (period 1, 42.25; period 2, 41.83; period 3, 31; F = 1.369; P = 0.298). There was a significant reduction in the mean number of ECT treatments commenced in northern Glasgow (period 1, 91.25; period 2, 51; period 3, 33.33; F = 10.06; P = 0.04).</p>
<p>Conclusions: In northern Glasgow, where there have been 2 site closures since 1996, ECT use has declined. This trend was not replicated in the south of the city. This would suggest that the closure of ECT centers does reduce the use of ECT. However, there may be a number of confounding variables that could not be factored into the analysis because of lack of available data.</p>
Alien Registration- Crabb, Harry M. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/24173/thumbnail.jp
Alien Registration- Crabb, Harry M. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/24173/thumbnail.jp
Alien Registration- Crabb, Harry M. (Portland, Cumberland County)
https://digitalmaine.com/alien_docs/24173/thumbnail.jp
1992 NASA Life Support Systems Analysis workshop
The 1992 Life Support Systems Analysis Workshop was sponsored by NASA's Office of Aeronautics and Space Technology (OAST) to integrate the inputs from, disseminate information to, and foster communication among NASA, industry, and academic specialists. The workshop continued discussion and definition of key issues identified in the 1991 workshop, including: (1) modeling and experimental validation; (2) definition of systems analysis evaluation criteria; (3) integration of modeling at multiple levels; and (4) assessment of process control modeling approaches. Through both the 1991 and 1992 workshops, NASA has continued to seek input from industry and university chemical process modeling and analysis experts, and to introduce and apply new systems analysis approaches to life support systems. The workshop included technical presentations, discussions, and interactive planning, with sufficient time allocated for discussion of both technology status and technology development recommendations. Key personnel currently involved with life support technology developments from NASA, industry, and academia provided input to the status and priorities of current and future systems analysis methods and requirements
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Improving Visual Field Examination of the Macula Using Structural Information
Purpose: To investigate a novel approach for structure-function modeling in glaucoma to improve visual field testing in the macula.
Methods: We acquired data from the macular region in 20 healthy eyes and 31 with central glaucomatous damage. Optical coherence tomography (OCT) scans were used to estimate the local macular ganglion cell density. Perimetry was performed with a fundus-tracking device using a 10-2 grid. OCT scans were matched to the retinal image from the fundus perimeter to accurately map the tested locations onto the structural damage. Binary responses from the subjects to all presented stimuli were used to calculate the structure-function model used to generate prior distributions for a ZEST (Zippy Estimation by Sequential Testing) Bayesian strategy. We used simulations based on structural and functional data acquired from an independent dataset of 20 glaucoma patients to compare the performance of this new strategy, structural macular ZEST (MacS-ZEST), with a standard ZEST.
Results: Compared to the standard ZEST, MacS-ZEST reduced the number of presentations by 13% in reliable simulated subjects and 14% with higher rates (≥20%) of false positive or false negative errors. Reduction in mean absolute error was not present for reliable subjects but was gradually more important with unreliable responses (≥10% at 30% error rate).
Conclusions: Binary responses can be modeled to incorporate detailed structural information from macular OCT into visual field testing, improving overall speed and accuracy in poor responders.
Translational Relevance: Structural information can improve speed and reliability for macular testing in glaucoma practice
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