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61.
Piotr Politański Elźbieta Rajkowska Marcin Brodecki Andrzej Bednarek Marek Zmyślony 《Bioelectromagnetics》2013,34(4):333-336
The aim of this study was to investigate the effect of static magnetic fields (SMF) on reactive oxygen species induced by X‐ray radiation. The experiments were performed on lymphocytes from male albino Wistar rats. After exposure to 3 Gy X‐ray radiation (with a dose rate of 560 mGy/min) the measurement of intracellular reactive oxygen species in lymphocytes, using a fluorescent probe, was done before exposure to the SMF, and after 15 min, 1 and 2 h of exposure to the SMF or a corresponding incubation time. For SMF exposure, 0 mT (50 µT magnetic field induction opposite to the geomagnetic field) and 5 mT fields were chosen. The trend of SMF effects for 0 mT was always opposite that of 5 mT. The first one decreased the rate of fluorescence change, while the latter one increased it. Bioelectromagnetics 34:333–336, 2013. © 2012 Wiley Periodicals, Inc. 相似文献
62.
63.
64.
A. Der Van Linde 《Biometrical journal. Biometrische Zeitschrift》1989,31(3):371-378
Papadakis' method is shown to be an example of an estimation procedure for a heterogeneity function localized in a reproducing kernel Hilbert space. Within this framework some current models for the evaluation of field trials are discussed. 相似文献
65.
In the laboratory, the vertical migration of Aphelenchoides besseyi was favored by rough surfaces and an inverse water gradient. In relation th gravity, the nematode migrated down or up equally, a circumstance suggesting that a geotaxis was not involved. Stems of rice seedlings were effective surfaces for vertical migration of nematodes only when the stems were continuously supplied with moisture. 相似文献
66.
Release of N, retention in soil, availability to a subsequent crop and total recovery of N derived from different15N-labelled plant materials decomposing in soil was investigated in two field experiments. In the first experiment five different
plant species (white clover, red clover, subterranean clover, field bean and timothy) and in the second subterranean clover
of different maturity (2,3 and 4 months old) were buried in mesh bags in the soil and allowed to decompose for 10 and 4 months,
respectively.
Most of the N released from the decaying plant materials was retained in the soil (27–46% of input). The subsequent crop (barley)
took up 6–25% of input. The uptake correlated with the amount of N released from the decomposing material (r=0.936*, I experiment). Similar amounts of subterranean clover N were taken up by barley regardless to whether the material was buried
in soil in the previous autumn or just before sowing of the crop. At the end of the experiments, the total recovery of the
introduced plant-derived N varied between 89 and 102%. The results present evidence that the ability of the soil to retain
plant-derived N is strong in comparison with the ability of the subsequent crop and different loss mechanisms to remove it. 相似文献
67.
Yoshinari Tanaka 《Evolution; international journal of organic evolution》1996,50(2):512-523
Social selection is presented here as a parallel theory to sexual selection and is defined as a selective force that occurs when individuals change their own social behaviors, responding to signals sent by conspecifics in a way to influence the other individuals' fitness. I analyze the joint evolution of a social signal and behavioral responsiveness to the signal by a quantitative-genetic model. The equilibria of average phenotypes maintained by a balance of social selection and natural selection and their stability are examined for two alternative assumptions on behavioral responsiveness, neutral and adaptive. When behavioral responsiveness is neutral on fitness, a rapid evolution by runaway selection occurs only with enough genetic covariance between the signal and responsiveness. The condition for rapid evolution also depends on natural selection and the number of interacting individuals. When signals convey some information on signalers (e.g., fighting ability), behavioral responsiveness is adaptive such that a receiver's fitness is also influenced by the signal. Here there is a single point of equilibrium. The equilibrium point and its stability do not depend on the genetic correlation. The condition needed for evolution is that the signal is beneficial for receivers, which results from reliability of the signal. Frequency-dependent selection on responsiveness has almost no influence on the equilibrium and the rate of evolution. 相似文献
68.
Differential Effects of Tachykinins Injected Intranigrally on Striatal Dopamine Metabolism 总被引:2,自引:1,他引:1
The effects of intranigral injection of kassinin, eledoisin, and substance P on striatal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) contents as well as circling behavior were studied in rats. Kassinin and eledoisin produced a marked dose-dependent increase of DOPAC concentrations in the ipsilateral striatum, as well as in the number of contralateral circlings. Substance P produced a similar but weaker effect. At the larger dose (5 nmol), the three tachykinins also induced an increase of DA concentrations in the ipsilateral striatum. The rank order of activity was kassinin greater than eledoisin greater than substance P. These results suggest that tachykinins stimulated the nigro-striatal dopaminergic system by accelerating the dopamine metabolism in striatum. 相似文献
69.
I. Tattersall 《Human Evolution》1989,4(2-3):117-124
Closely related living mammal species present numerous difficulties of recognition and delineation, not least because populations as well as individual organisms fulfill both genetic and economic functions. However, since species are often distributed geographically across multiple ecosystems or environments, it is evident that species as wholes, except where coterminous with the local populations of which they are composed, cannot be said to play unitary ecological roles. Aspects of the economic activity of organisms thus may not be admitted as elements in species recognition. Those who study the behavior of mammals in their natural habitats must therefore focus upon behaviors which preserve the genetic integrity of species if they wish to contribute to the systematic question of species identification. «Isolation» concepts of species are not served by data of this kind, since they emphasize interspecies discontinuities; the «recognition» concept of species, however, specifically focuses upon behaviors of this kind as they contribute to the «Specific-Mate Recognition System». Among primates such behaviors are likely to involve signalling of various kinds; where this is visual it is reasonable to expect to find morphological or chromatic correlates; where such cues are auditory or, to a lesser extent, olfactory, it is less probable that such correlates will be found to exist. 相似文献
70.
Richard O. Prum 《Evolution; international journal of organic evolution》1994,48(5):1657-1675
Phylogenetic analyses of lekking, lek spatial organization, and cooperative and coordinated lek display in the manakins (Aves: Pipridae) demonstrate that variation in social behavior in the group has a strong, phylogenetic component. Two of the three classes of social behavior examined also show significant phylogenetic constraints. Current adaptive plasticity models are insufficient to explain the phylogenetic variation in these behaviors in the manakins. These findings support the conclusion that vertebrate reproductive social behavior has an evolutionary history, and that it is not determined solely by adaptive individual plasticity to current conditions. The evolution of social behavior, particularly through sexual selection, can have historical consequences that can limit subsequent behavioral adaptation. 相似文献