5,290 research outputs found
Analysis and Experimental Tests of a High-Performance Evacuated Tubular Collector
A high-performance collector based on the use of all-glass, evacuated tubular collector elements is described and analyzed, and supporting experimental data presented. The collector operated with excellent efficiency at temperatures high enough to drive existing air conditioning units, and showed good performance under diffuse light and low insolation conditions. Collector efficiency was insensitive to operating temperature, ambient temperature, and wind speed. In addition, air, as well as liquid, can be used as the heat transfer fluid, with no significant performance penalty. While the equations governing the useful energy produced can be cast in a form similar to that for flat plate collectors, several important parameters were unique in a number of respects. The loss coefficient was unusually low, while the flow factor and effective insolation were unusually high
Lyophilisation of lentiviral pseudotypes for the development and distribution of virus neutralisation assay kits for rabies, Marburg and influenza viruses
Purpose: Some conventional serological assays can accurately quantify neutralising antibody responses raised against epitopes on virus glycoproteins, enabling mass vaccine evaluation and serosurveillance studies to take place. However, these assays often necessitate the handling of wild-type virus in expensive high biosafety laboratories, which restricts the scope of their application, particularly in resource-deprived areas. A solution to this issue is the use of lentiviral pseudotype viruses (PVs)—chimeric, replication-deficient virions that imitate the binding and entry mechanisms of their wild-type equivalents. Pseudotype virus neutralisation assays (PVNAs) bypass high biosafety requirements and yield comparable results to established assays. This study explores the potential for using lyophilisation of pseudotypes as a cost-effective, alternative means for production, distribution and storage of a PVNAbased diagnostic kit. Methods & Materials: Rabies, Marburg and H5 subtype Influenza virus pseudotypes were each suspended in cryoprotectant solutions of various molarities and subjected to freeze-drying before incubation at a variety of temperatures, humidities and time periods. Samples were then employed in antibody neutralisation assays using specific sera. Results: High levels of PV titre were retained post-lyophilisation, with acceptable levels of virus activity maintained even after medium-term storage in tropical conditions. Also, the performance of PVs in neutralisation assays was not affected by the lyophilisation process. Conclusion: These results confirm the viability of a freeze-dried PVNA-based diagnostic kit, which could considerably facilitate in-field serology for a number of clinically important viruses
Science-fiction et cognition
Cet article tente de faire le point sur les contributions scientifiques de la psychologie cognitive à la théorie du genre, et celle du cinéma de science-fiction en particulier. Le répertoire thématique de la science-fiction est mis à profit pour illustrer la typologie des schémas cognitifs proposée par David Bordwell. La théorie des émotions de Torben Grodal est aussi évaluée en fonction de sa capacité à expliquer une dimension affective de la science-fiction : le sentiment de l'éloignement.This article seeks to evaluate the scientific contributions of cognitive psychology to genre theory and science-fiction film theory in particular. The science-fiction genre's thematic lexicon is called upon to illustrate the concept of cognitive schemata, as put forth by David Bordwell. Torben Grodal's cognitive theory of emotions is also examined for its potential explanatory value in regards to the science-fiction genre's emotional parameter, estrangement
Thermal detectors as X-ray spectrometers
Sensitive thermal detectors should be useful for measuring very small energy pulses, such as those produced by the absorption of X-ray photons. The measurement uncertainty can be very small, making the technique promising for high resolution nondispersive X-ray spectroscopy. The limits to the energy resolution of such thermal detectors are derived and used to find the resolution to be expected for a detector suitable for X-ray spectroscopy in the 100 eV to 10,000 eV range. If there is no noise in the thermalization of the X-ray, resolution better than 1 eV full width at half maximum is possible for detectors operating at 0.1 K. Energy loss in the conversion of the photon energy to heat is a potential problem. The loss mechanisms may include emission of photons or electrons, or the trapping of energy in long lived metastable states. Fluctuations in the phonon spectrum could also limit the resolution if phonon relaxation times are very long. Conceptual solutions are given for each of these possible problems
Wintering strategies of an Arctic-nesting goose: costs of migration and over-wintering for Pacific black brant
Thesis (M.S.) University of Alaska Fairbanks, 2005Birds wintering in different climates may have different strategies for storing and using energy. We documented changes in body morphology and composition of Pacific Black Brant (Branta bernicla nigricans) wintering in Alaska and Baja California and modeled the energetic costs of wintering at each location. We compared costs associated with two different wintering strategies: 1) to remain in an unstable and harsh environment but close to breeding grounds, or 2) to migrate long distances to a mild environment, but distant from breeding grounds. Despite dramatic differences in the timing and magnitude of energetic costs between sites, Brant stored similar amounts of lipid and maintained similar body mass throughout winter. Brant operate under similar physiological bounds but changes in organ mass and nutrient storage took place within these bounds. This flexibility allowed Brant to employ two contrasting winter strategies. We suggest that there may be reproductive and energetic advantages associated with shortening migration distance and remaining in Alaska over winter. The number of Brant wintering in Alaska should continue to increase if constraints on food intake do not impede energy storage and survival is similar between sites
Locally continuously perfect groups of homeomorphisms
The notion of a locally continuously perfect group is introduced and studied.
This notion generalizes locally smoothly perfect groups introduced by Haller
and Teichmann. Next, we prove that the path connected identity component of the
group of all homeomorphisms of a manifold is locally continuously perfect. The
case of equivariant homeomorphism group and other examples are also considered.Comment: 14 page
Modal analysis computer program package
Modal analysis computer program package for finding frequencies and mode shapes of any linear discrete system governed by generalized eigenvalue equatio
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