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281.
Merritt Dustin; MacLean Evan L.; Jaffe Sarah; Brannon Elizabeth M. 《Canadian Metallurgical Quarterly》2007,121(4):363
Research over the last 25 years has demonstrated that animals are able to organize sequences in memory and retrieve ordered sequences without language. Qualitative differences have been found between the serial organization of behavior in pigeons and monkeys. Here the authors test serial ordering abilities in ring-tailed lemurs, a strepsirrhine primate whose ancestral lineage diverged from that of monkeys, apes, and humans approximately 63 million years ago. Lemurs' accuracy and response times were similar to monkeys, thus suggesting that they may share mechanisms for serial organization that dates to a common primate ancestor. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
282.
J.E. Jaffe 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2007,580(3):1378-1382
The causes of energy nonlinearity (nonproportionality) in gamma-ray spectroscopy of scintillators have not been fully explained quantitatively, but are believed to involve the spatial density of thermalized electrons and holes, their transport and interactions, and competition between radiative and nonradiative recombination. Here, we relate electron–hole density to the initial ray's energy through expressions for the stopping power and distance, and then attempt to fit some “plateau-type” (e.g. BaF2, Lu2SiO5, etc.) light curves via competing radiative and nonradiative processes obeying different energy power laws. We find that reasonable power laws and the assumption of a uniform energy density in the excited region lead to a fairly good agreement with many experimental curves. We then show that a simple approximation for averaging over regions of different excitation density leads to improved agreement with experiment, at the expense of making it more difficult to uncover the underlying kinetics from the experimental data. These considerations should carry over to more sophisticated models or simulations of scintillation processes. 相似文献
283.
SH2 domain-mediated activation of an SRC family kinase is not required to initiate Ca2+ release at fertilization in mouse eggs 总被引:1,自引:0,他引:1
SRC family kinases (SFKs) function in initiating Ca2+ release at fertilization in several species in the vertebrate evolutionary line, but whether they play a similar role in mammalian fertilization has been uncertain. We investigated this question by first determining which SFK proteins are expressed in mouse eggs, and then measuring Ca2+ release at fertilization in the presence of dominant negative inhibitors. FYN and YES proteins were found in mouse eggs, but other SFKs were not detected; based on this, we injected mouse eggs with a mixture of FYN and YES Src homology 2 (SH2) domains. These SH2 domains were effective inhibitors of Ca2+ release at fertilization in starfish eggs, but did not inhibit Ca2+ release at fertilization in mouse eggs. Thus the mechanism by which sperm initiate Ca2+ release in mouse eggs does not depend on SH2 domain-mediated activation of an SFK. We also tested the small molecule SFK inhibitor SU6656, and found that it became compartmentalized in the egg cytoplasm, thus suggesting caution in the use of this inhibitor. Our findings indicate that although the initiation of Ca2+ release at fertilization of mammalian eggs occurs by a pathway that has many similarities to that in evolutionarily earlier animal groups, the requirement for SH2 domain-mediated activation of an SFK is not conserved. 相似文献