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91.
Teat and gland cistern of the mammary glands of five dairy cows, five goats and five sheep were scanned in a water bath during alpha- and beta-adrenergic agonist and oxytocin administration. A 5 MHz linear array scanner was used to create vertical cut pictures with the scan plane longitudinally through the teat channel. The i.v. injection of the alpha-adrenergic agonist phenylephrine (30 micrograms/kg) induced diminution of the section area through teat and gland cistern by 38 +/- 17% on average within 1 min in all three species. In contrast, the i.v. injection of the beta-adrenergic agonist isoproterenol (1 microgram/kg) did not change the cisternal areas. The i.v. injection of oxytocin (2.0 x 10(-3) i.u./kg) elicited an enlargement of teat and gland cistern area by 48 +/- 12% on average. Ultrasonography proved to be a valuable system for visualizing changes of the cisternal volume. Smooth muscle contractions in response to phenylephrine administration are thought to cause area reduction, whereas an expected smooth muscle relaxation after injection of isoproterenol could not be observed by ultrasonography. Milk ejection as induced by oxytocin administration caused dramatic enlargement of the cistern area in all three species. 相似文献
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The delay-limited throughput of an ad hoc wireless network confined to a finite region is investigated. An approximate expression for the achievable throughput as a function of the maximum allowable delay is obtained. It is found that: 1) for moderate values of the delay d, the throughput that can be achieved by taking advantage of the motion increases as d/sup 2/3/ and 2) for a fixed value of d, the dependence of the achievable throughput on the number of nodes n is n/sup -1/3/. A transmission and relaying strategy ensuring continuous information flow is constructed. It is shown that there exists a critical value of the delay such that: 1) for values of the delay d below the critical delay, the throughput does not benefit appreciably from the motion and 2) the dependence of the critical delay on the number of nodes is a very slowly increasing function (n/sup 1/14/). Finally, asymptotic optimality of the proposed strategy in a certain class is shown. 相似文献
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Substitution of SiO2 with CeO2 in the ternary sodium borosilicate system was found to produce phase-separable glasses. Heat treatment of these glasses resulted in separation into two different phases. The one phase enriched in sodium borate was then leached out leaving a CeO2-rich framework. The structure of the leached material was crystalline (Pt/Rh crucible melt) which changed to a rather net-like appearance if Al2O3 resulting from erosion of alumina crucibles was added. B2O3 remained partially in the insoluble CeO2-skeleton. X-ray diffraction analysis of leached material proved the presence of crystalline cubic CeO2 and cerium borate (metaborate of the aragonite type) in Pt/Rh crucible melts, whereas cubic CeO2, 2Al2O3 · B2O3 and traces of sodium borate were detected in Al2O3 containing melts. The specific surface areas of the leached materials ranged between 25 and 120m2g–1 while the main radii of interconnected pores were calculated to be between 0.5 and 17nm. A sintering temperature of about 1500° C was estimated from void volume and bulk density measurements. 相似文献
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Research suggests that the poor performance of depressed patients on memory tests reflects cautious response criteria rather than reduced accessibility of memories. Studies of recognition memory enable this issue to be addressed. The present experiment provides the first clear demonstration of a deficit in recognition memory in depression that is not explicable in terms of response bias. A subsidiary concern was to examine the effect of requiring subjects to vocalize words on presentation. This had no significant effects on "hits," but it interacted with depression on "false alarms," suggesting that discrepant claims in the literature regarding the effects of depression on false alarms may be attributable to procedural variations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Content-based classification, search, and retrieval of audio 总被引:5,自引:0,他引:5
Many audio and multimedia applications would benefit from the ability to classify and search for audio based on its characteristics. The audio analysis, search, and classification engine described here reduces sounds to perceptual and acoustical features. This lets users search or retrieve sounds by any one feature or a combination of them, by specifying previously learned classes based on these features, or by selecting or entering reference sounds and asking the engine to retrieve similar or dissimilar sounds 相似文献
100.