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951.
Conduction velocities of compound action potentials of sensory axons of alteral superficial radial (LSR) and dorsal ulnar nerves (DUN) of the dog were determined by averaging potentials evoked and recorded through subcutaneous needle electrodes. Suitable locations for electrodes were identified and specificities of sites for LSR and DUN were verified by recording before and after cutting the nerves. Stimulus rates of 4/second to 20/second did not markedly affect conduction velocities. Increasing stimulus intensity in steps from threshold to 8 X threshold recruited more axons into the compound action potentials but resulted in interference from movement and muscle potentials at 4 X or 8 X threshold. Mean conduction velocities at 2 X threshold were: LSR = 61.7 +/- 0.76 SEM; DUN = 68.1 +/- 2.71 SEM. 相似文献
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Cadmium, nickel, lead, and zinc in earthworms from roadside soil 总被引:1,自引:0,他引:1
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Joensen KD Voutov P Szentgyorgyi A Roll J Gorenstein P Høghøj P Christensen FE 《Applied optics》1995,34(34):7935-7944
Extremely broadband grazing-incidence multilayers for hard-x-ray reflection can be obtained by a gradual change of the layer thicknesses down through the structure. Existing approaches for designing similar neutron optics, called supermirrors, are shown to provide respectable performance when applied to x-ray multilayers. However, none of these approaches consider the effects of imperfect layer interfaces and absorption in the overlying layers. Adaptations of neutron designs that take these effects into account are presented, and a thorough analysis of two specific applications (a single hard-x-ray reflector and a hard-x-ray telescope) shows that an improved performance can be obtained. A multilayer whose bilayer thicknesses are given by a power law expression is found to provide the best solution; however, it is only slightly better than some of the adapted neutron designs. 相似文献
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T Bryndorf B Christensen M Vad J Parner MP Carelli BE Ward KW Klinger J Bang J Philip 《Canadian Metallurgical Quarterly》1996,59(4):918-926
We developed a 1-d FISH assay for detection of numerical chromosome abnormalities in uncultured chorionic villus samples (CVS). Probes specific for chromosomes 13, 18, 21, X, and Y were used to determine ploidy by analysis of signal number in hybridized nuclei. Aneuploidy detection using this assay was directly compared with the results obtained by conventional cytogenetic analysis in a consecutive, clinical study of 2,709 CVS and placental samples. The FISH assay yielded discrete differences in the signal profiles between cytogenetically normal and abnormal samples. On the basis of these results, we generated FISH-assay cutoff values that discriminated between karyotypically normal and aneuploid samples. Samples with mosaicism and a single sample with possible heritable small chromosome X probe target were exceptions and showed poor agreement between FISH results and conventional cytogenetics. We conclude that the FISH assay may act as a more accurate and less labor-demanding alternative to "direct" CVS analysis. 相似文献
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Rehan O’Grady Roderich Groß Anders Lyhne Christensen Marco Dorigo 《Autonomous Robots》2010,28(4):439-455
Robots are said to be capable of self-assembly when they can autonomously form physical connections with each other. By examining
different ways in which a system can use self-assembly (i.e., different strategies), we demonstrate and quantify the performance costs and benefits of (i) acting as a physically larger self-assembled entity,
(ii) letting the system choose when and if to self-assemble, (iii) coordinating the sensing and actuation of the connected
robots so that they respond to the environment as a single collective entity. Our analysis is primarily based on real world
experiments in a hill crossing task. The configuration of the hill is not known by the robots in advance—the hill can be present
or absent, and can vary in steepness and orientation. In some configurations, the robots can overcome the hill more quickly
by navigating individually, while other configurations require the robots to self-assemble to overcome the hill. We demonstrate
the applicability of our self-assembly strategies to two other tasks—hole crossing and robot rescue—for which we present further
proof-of-concept experiments with real robots. 相似文献