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51.
A distinction is made between atheromatous plaque formation and arteriosclerosis, only this second process is strictly age-dependent. Interactions between lipids and constituents of the vascular wall are however involved in both processes, although by different mechanisms. The progressive increase with age of elastase activity is a second important factor in the age-dependent progression of arteriosclerosis. The fragmentation of elastic fibers produces elastin peptides, present in the circulating blood in microgram/ml conc-s, increasing in several arteriopathies. The constant presence of elastin peptides in the circulation maintains activated the elastin receptor (16) on endothelial cells producing NO* with vasorelaxing activity (18). The simultaneous production of superoxyde leads to the formation of peroxynitrate, neutralized by reduced glutathion. This process, maintained over decades may well impair the antiradical defense mechanisms of the cells and deprive the endothelium from the vasorelaxing activity of NO*. We propose therefore that the maintained activation of the elastin receptor with free radical and lytic enzyme production might well represent the initiating process underlying atherogenesis.  相似文献   
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Robert D. Cook 《Thin》1985,3(4):365-372
A cylindrical tank is mounted with its axis horizontal. Supports on either side run lengthwise. If the tank wall is thin, deformations significantly affect the stresses, so that standard stress formulae (which ignore deformations) may over-estimate stresses by a factor of ten or more. In this paper, deformations are accounted for by a nonlinear analysis. Stresses and deformed shapes are reported for various positions of the supports, radius to thickness ratios, and depths of fill.  相似文献   
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Nicht-funktionale Anforderungen an ein Softwaresystem beschreiben Aspekte, die nicht direkt die Funktionalit?t, wie sie der Benutzer sieht, betreffen.  相似文献   
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Assuming significant technical success in the ITER project by the year 2015, it is likely that governments will want to develop a more comprehensive plan for DT tokamak fusion power commercialization. To provide a glimpse into many of the related issues, we construct conversations between the director of the U.S. fusion program and three specialists key to commercial fusion success: an environment and safety regulator, an environmentalist, and an electric generation investor. The insights from these imagined conversations will hopefully be of value as tokamak fusion power proponents plan beyond ITER.  相似文献   
57.
When liquid water contacts a zirconium-barium-lanthanum fluoride glass, at least three different processes occur. Barium and zirconium fluoride dissolve into the water, water penetrates into the glass, and zirconium fluoride crystals grow on the glass surface, in static solution. The rate of dissolution, as measured by solution analysis, is possibly controlled by diffusion in the solid surface; surface blockage and surface reactions are other possible kinetic steps involved. Diffusion in solution is not the controlling mechanism. Hydrogen profiles in the glass surface suggest that the penetration rate of water into the glass is controlled by diffusion and a surface reaction.  相似文献   
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Common pigweed,Amaranthus hybridus L., is a favorite host of the beet army worm (BAW),Spodoptera exigua L. Chemicals extracted from homogenized pigweed with distilled water, ethanol, or dichloromethane and sprayed back on pigweed deterred oviposition by the BAW. Similarly, water extracts of frass from conspecific larvae or southern armyworm (SAW) larvae,S. eridania (Cramer), fed pigweed leaves and sprayed back on pigweed plants also deterred BAW oviposition, thus confirming that deterrence was due to plant allelochemics rather than specific compounds associated with the metabolic or excretory products of the larvae. Confirmation of the presence of oviposition-deterring chemicals in pigweed was used to explain a previously observed seasonal displacement of BAW by SAW on pigweed in the field.Mention of a commercial or proprietary product does not constitute an endorsement by the USDA.  相似文献   
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The generation effect occurs if people remember items they complete from fragments better than complete items they read. Four experiments investigate two questions. When does the effect occur, and why does it do so? Targets generated in related contexts are recognized better than read targets, and they are recalled better with the contexts as cues; the contexts are recognized equally well, and the relation between the context and target is not enhanced by generation. Furthermore, generated items exceed items read in pure lists even when read ones from the mixed list are no worse than the controls. The generation effect is real; it is not an artifact. However, there is nothing special about generation. Generating is a type of encoding, and like any other type of encoding, its effects are maximal on tests that require subjects to do again whatever they did at study. Generating makes targets distinctive by contrasting them with other relatives of the context, and, as a result, the targets enjoy benefits in later discriminations within their family. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
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