5,508 research outputs found

    Evolution of adaptation mechanisms: adaptation energy, stress, and oscillating death

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    In 1938, H. Selye proposed the notion of adaptation energy and published "Experimental evidence supporting the conception of adaptation energy". Adaptation of an animal to different factors appears as the spending of one resource. Adaptation energy is a hypothetical extensive quantity spent for adaptation. This term causes much debate when one takes it literally, as a physical quantity, i.e. a sort of energy. The controversial points of view impede the systematic use of the notion of adaptation energy despite experimental evidence. Nevertheless, the response to many harmful factors often has general non-specific form and we suggest that the mechanisms of physiological adaptation admit a very general and nonspecific description. We aim to demonstrate that Selye's adaptation energy is the cornerstone of the top-down approach to modelling of non-specific adaptation processes. We analyse Selye's axioms of adaptation energy together with Goldstone's modifications and propose a series of models for interpretation of these axioms. {\em Adaptation energy is considered as an internal coordinate on the `dominant path' in the model of adaptation}. The phenomena of `oscillating death' and `oscillating remission' are predicted on the base of the dynamical models of adaptation. Natural selection plays a key role in the evolution of mechanisms of physiological adaptation. We use the fitness optimization approach to study of the distribution of resources for neutralization of harmful factors, during adaptation to a multifactor environment, and analyse the optimal strategies for different systems of factors

    The effect of the relative nuclear size on the nucleus-nucleus interactions

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    The experimental data on the interactions of light nuclei (d, He(4), C(12)) at the momentum 4.2 GeV/cA with the carbon nuclei were taken in the 2-m propane bubble chamber. The distributions in the number of interacting nucleons, the spectra of protons, the mean energies of secondary pions and protons, the mean fractions of energy transferred to the pion and nucleon components are presented. The results of the investigation of the mechanism of nucleus-nucleus interactions can be used to calculate the nuclear cascades in the atmosphere

    On the T-Odd Quark Fragmentation Function and on Transversal Handedness

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    The first probe of the correlation of the T-odd one-particle fragmentation function responsible for the left--right asymmetry of fragmentation of a transversely polarized quark is done by using the 1991-95 DELPHI data for Z2Z\to 2-jet decay. Integrated over the fraction of longitudinal and transversal momenta, this correlation is of 1.5% order, which means order of 13% for the analyzing power. A rather large (10\approx 10%) handedness transversal to the production plane was observed in the diffractive production of (ππ+π\pi^-\pi^+\pi^-) triples from nuclei by the 40GeV/cπ40 GeV/c \pi^---beam. It was shown that the phenomenon has a clear dynamic origin and resembles the single spin asymmetry behavior. All this makes us hope to use this effects in polarized DIS experiments for transversity measurement.Comment: 10 pp, 5 epsfig, Latex 2e, szjp.cls, epsfig.sty, wrapfig.sty included. Talk in "Spin and Symmetry - Praha98". To be published in Czechoslovak Journal of Physics, Supp

    Evaluation of Carbon Assimilation by Regenerating Soils of the Central Black Earth Region of Russia

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    The study presents the options for the estimation of soil assimilation rates with carbon regenerating after an anthropogenic influence in the Central Black Earth region of Russia. The evaluation methodology is based on the use of mathematical models of the trend component processes for the humus horizon and humus accumulation development in Forest-Steppe Black Earth area

    A Frequency-Domain Criterion for Global Stability of Systems with Angular Coordinates

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