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151.
152.
Yi -Cheng Zhang Maurizio Serva Mikhail Polikarpov 《Journal of statistical physics》1990,58(5-6):849-861
Interesting physics emerges from studying a population of reproducing individuals. Each can be regarded as a random walker, but it can either duplicate or die. Novel features of the collective behavior are quite surprising: if individuals reproduce or die freely, the life expectation is proportional to the size of the population, and if it is kept constant, the center of mass moves in space as if it were a single walker (i.e., the diffusion constant is independent of population's size). Biology-inspired interactions are also considered. 相似文献
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154.
For a linear anisotropic hyperelastic body subjected to a state of pure strain it is shown that there are at least three directions such that the stress and strain tensors are coaxial. 相似文献
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157.
We study the dynamics of a noisy network of spiking neurons with spike-frequency adaptation (SFA), using a mean-field approach, in terms of a two-dimensional Fokker-Planck equation for the membrane potential of the neurons and the calcium concentration gating SFA. The long time scales of SFA allow us to use an adiabatic approximation and to describe the network as an effective nonlinear two-dimensional system. The phase diagram is computed for varying levels of SFA and synaptic coupling. Two different population-bursting regimes emerge, depending on the level of SFA in networks with noisy emission rate, due to the finite number of neurons. 相似文献
158.
The complete list of constraint manifolds having the group structure is given. 相似文献
159.
OBJECTIVES: To inform on Teratology Information Services (TIS) in Europe, their history, function and activity in preventing congenital malformations. CONCLUSIONS: Clinical teratology tries to identify human teratogens. TIS play an important role in public health by providing counsel on known reproductive risks and conducting specific research. This has led to a reduction in unnecessary fears of pregnant women and pregnancy terminations, as well as to better, more appropriate drug selection to treat acute or chronic disease. In addition, TIS units also conduct prospective studies and inform the public and physicians of the possible effects of environmental agents on the developing embryo and fetus. 相似文献
160.
Maurizio Pandolfi 《Meccanica》1973,8(4):236-242
Summary A numerical technique used in gasdynamics is here applied to the solution of one-dimensional unsteady flows in channels in
the spirit of the shallow water theory. Its most important feature is the explicit treatment of imbedded bores generated in
the flow by coalescence of characteristics. Four numerical examples are presented to show possible applications of the method.
Sommario Si mostra qui l'applicazione al calcolo di correnti non stazionarie in canali, secondo la formulazione della “shallow water theory”, di metodologie numeriche già usate in gasdinamica. Il trattamento esplicito di risalti, formati per coalescenza di caratteristiche, costituisce il punto particolare del lavoro. Vengono quindi presentati quattro esempi di applicazione della metodologia numerica.相似文献