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301.
利用参数模型提取诱发脑电(EP)及其在40Hz EEG和EP间关联研究中的应用 总被引:1,自引:0,他引:1
提出一种基于参数模型的信息处理方法,用于诱发脑电的提取,这种方法可以得到单次EP波形的无偏,最小方差估计,用刺激强度实验验证了该方法在实际情况下的有效,进一步将其应用于刺激前EEG与EP的关联研究,得到了刺激前40Hz的EEG成分与晚潜伏期听觉诱发脑电幅度有极显著负相关的结果,表明刺激前及状态确定对EP有影响。 相似文献
302.
F. A. Popp W. Nagl K. H. Li W. Scholz O. Weingärtner R. Wolf 《Cell biochemistry and biophysics》1984,6(1):33-52
The phenomenon of ultraweak photon emission from living systems was further investigated in order to elucidate the physical
properties of this radiation and its possible source. We obtained evidence that the light has a high degree of coherence because
of (1) its photon count statistics, (2) its spectral distribution, (3) its decay behavior after exposure to light illumination,
and (4) its transparency through optically thick materials. Moroever, DNA is apparently at least an important source, since
conformational changes induced with ethidium bromide in vivo are clearly reflected by changes of the photon emission of cells.
The physical properties of the radiation are described, taking DNA as an exciplex laser system, where a stable state can be
reached far from thermal equilibrium at threshold. 相似文献
303.
The dielectric dispersion of isolated intact mitochondria in suspension has been measured between 10 kHz and 500 MHz. In isotonic KCI media at 4°C, the mitochondria maintained their characteristic ‘double membrane’ structure as examined by electron microscopy, and the observed dispersion curves were successfully simulated in terms of a superposition of two sub-dispersions having different characteristic frequencies and different permittivity magnitudes. Taking these observations into account we analyzed the dispersion data on the basis of a ‘double-shell’ model in which two concentric shells are meant to represent the mitochondrial outer and inner membranes. The analyses by a computerized curve-fitting method revealed that: (i) electric capacities for the outer and the inner membrane are 1.7 and 0.5 μF/cm2, respectively, (ii) relative permittivity for the inner compartment (or the equivalent homogeneous matrical space) = 50–60, (iii) outer compartment-to-external conductivity ratio = 0.4–0.6, and (iv) inner compartment-to-external conductivity ratio = 0.14. The implications of these parameter values are discussed with due attention paid to the limitations inherent in our ‘double-shell’ model approach. 相似文献
304.
Short-term variations in the relative catch in each of two or three interacting pheromone traps for the pea moth,Cydia nigricana (F.), were investigated for traps aligned along the wind. The proportional catch in each trap varied widely, although the mean values accorded with previous estimates. Over consecutive short intervals during a single trapping period the proportion caught in the centre trap of a three-trap line was constant. The proportion caught in the upwind trap of two-and three-trap lines showed trends in time. These trends differed between trapping periods, but two lines of traps operated simultaneously gave similar results to each other. It is suggested that these results, which are predicted by a model based on various components of moth orientation behaviour, are caused by changes in systematic behavioural processes, not random effects. Possible mechanisms are discussed.
Variations à court terme des captures deCydia nigricana dans des pièges à phéromones en interaction
Résumé Des données antérieures concernant les interactions entre des pièges à phéromone alignés le long du vent ont été utilisées pour déduire les caractéristiques du comportement d'orientation deC. nigricana. Ces données ont été introduites dans un modèle de simulation quantitative qui prédisait que quand les captures totales sur une ligne ont été regroupées sur une période globale de piégage, la proportion capturée dans chaque piège devrait aussi avoir des valeurs moyennes semblables, mais varie plus largement que précédemment indiqué. Les simulations concernant des intervalles consécutifs beaucoup plus courts pendant la même période de piégage ont suggéré une forme spécifique de cette variation.Cette note signale des variations à court terme dans la proportion capturée au piège qui confirment ces prédictions. Nous montrons que sur des intervalles consécutifs brefs pendant une simple période de piégage, la proportion capturée dans le piège central d'une ligne de 3 pièges est contstante, bien que sa valeur change suivant les périodes de piégage. La proportion capturée dans le piège face au vent de 2 ou 3 lignes de pièges suit cette tendance dans le temps, ce qui est généralement bien représenté avec des courbes simples. Ces tendances changent suivant les périodes de piégage, mais des lignes de pièges fonctionnant simultanément fournissaient des résultats similaires. On suggère que ces résultats sont dus à des changements dans des processus comportementaux systématiques et non à des effects aléatoires. Les mécanismes possibles sont discutés.相似文献
305.
In this paper, we examine allometric and sexual-selection explanations for interspecific differences in the amount of sexual
dimorphism among 60 primate species. Based on evidence provided by statistical analyses, we reject Leutenegger and Cheverud’s
[(1982). Int. J. Primatol.3:387-402] claim that body size alone is the major factor in the evolution of sexual dimorphism. The alternative proposed
here is that sexual selection due to differences in the reproductive potential of males and females is the primary cause of
sexual dimorphism. In addition, we propose that the overall size of a species determines whether the dimorphism will be expressed
as size dimorphism,rather than in some other form. 相似文献
306.
R. C. Griffiths 《Journal of mathematical biology》1984,21(1):67-75
Asymptotic distributions are derived for the number of non-mutant ancestors, at time t in the past, of a sample of n from a neutral infinite alleles model. Either the number of non-mutant ancestors L
n
(t) has a normal distribution or n-Ln(t) has a Poisson distribution as n , t 0. 相似文献
307.
In this paper we study a method for the identification of the unknown parameter of the periodic function and also the first component of the state vector, in a mathematical model which describes the evolution of some diseases with an oro-fecal transmission.To solve the identification problem we use a numerical method to integrate the differential equations system, which reproduces the stability properties of the above mentioned continuous system.The numerical methods which we propose can be applied also to a spatial semi discretization of the reaction-diffusion model which is a diffusive generalization of the system that we consider in this paper.Finally, through an analysis on both the continuous and the discrete system we also obtain a necessary condition on the experimental data in order that a periodic trajectory of the system exists.Work supported by: Progetto Finalizzato Controllo Malattie da Infezione-CNR and by Ministero Pubblica Istruzione 相似文献
308.
309.
Some optimal designs for sampling in two dimensions 总被引:1,自引:0,他引:1
310.