Continuous-discrete model of population dynamics with time lag in a reaction of intra-population self-regulative mechanisms

Continuous-discrete model of population dynamics is considered in current publication. It is assumed that death process of individuals has a continuous nature, and appearences of individuals of new generations are observed at fixed time moments. It is also assumed that population has non-overlapping generations, and for every generation self-regulative mechanisms have distributed time lag in reaction on population size changing. For particular case when death rate of individuals between fixed time moments corresponds to Verhulsts law, it was obtained that various cyclic regimes can be observed in phase space. For various values of model parameters the structure of domain in space of parameters, where chaotic dynamic regimes can be realized, is described

Three different ways for estimating Green Oak Leaf Roller dynamics type: OLS, MEP, and Almost-Bayesian approaches

The generalized discrete logistic model (GDLM) of population dynamics was used for fitting of the known empirical time series on the green oak leaf roller (Tortrix viridana L.) fluctuations in European part of Russian Federation (Korzukhin and Semevsky, 1992). The model was assumed to demonstrate satisfactory data approximation if and only if the set of deviations of the model and empirical data satisfied several statistical criterions (for fixed significance levels). Distributions of deviations between theoretical (model) trajectories and empirical datasets were tested for symmetry (with respect to the ordinate line by Kolmogorov-Smirnov, Mann - Whitney U-test, Lehmann - Rosenblatt, and Wald - Wolfowitz tests) and the presence or absence of serial correlation (the Swed-Eisenhart and ‘‘jumps up-jumps down’’ tests). Stochastic search in a space of model parameters show that the feasible set (set of points where all used tests demonstrate correct/required results) is not empty and, consequently, the model is suitable for fitting of empirical data. It is also allowed concluding that observed regime of population dynamics isn’t cyclic (if length of cycle is less than 1500 years) and can be characterized by the fast decreasing autocorrelation function (with further small fluctuations near zero level). Feasible set allows constructing almost-Bayesian estimations of GDLM parameters. For the situation when model parameters are stochastic variables algorithm of calculation of model trajectories is presented

About a dynamic model of interaction of insect population with food plant

In present paper there is the consideration of mathematical model of food plant (resource) - consumer (insect population) - pathogen system dynamics which is constructed as a system of ordinary differential equations. The dynamic regimes of model are analyzed and, in particular, with the help of numerical methods it is shown that trigger regimes (regimes with two stable attractors) can be realized in model under very simple assumptions about ecological and intra-population processes functioning. Within the framework of model it was assumed that the rate of food flow into the system is constant and functioning of intra-population selfregulative mechanisms can be described by Verhulst model. As it was found, trigger regimes are different with respect to their properties: in particular, in model the trigger regimes with one of stable stationary points on the coordinate plane can be realized (it corresponds to the situation when sick individuals in population are absent and their appearance in small volume leads to their asymptotic elimination); also the regimes with several nonzero stationary states and stable periodic fluctuations were found

Size quantization in metal films

Quantum size effect, predicted by I.M. Lifshits and A.M. Kosevich [Izv. Akad. Nauk SSSR, seriya fiz. 19, 395 (1955)], was investigates in a many works. In the basis of analysis of quantum size oscillations of thermodynamics and kinetic characteristics of metal films lies the quasiclassical quantization of component of momentum for isotropy model and quantization [S.S. Nedorezov, Zh. Eksp. Teor. Fiz. 51, 868 (1966) [Sov. Phys.-JETF 24, 578 (1967)]] of chord of constant-energy surface in the case of anisotropy energetic spectrum. In the given work the research of quantum size levels of energy of electrons in metal films is carried out by the method of J.M. Luttinger–W.Kohn. The exact conditions of size quantization are got

Effect of strain on stripe phases in the Quantum Hall regime

Spontaneous breaking of rotational symmetry and preferential orientation of stripe phases in the quantum Hall regime has attracted considerable experimental and theoretical effort over the last decade. We demonstrate experimentally and theoretically that the direction of high and low resistance of the two-dimensional (2D) hole gas in the quantum Hall regime can be controlled by an external strain. Depending on the sign of the in-plane shear strain, the Hartree-Fock energy of holes or electrons is minimized when the charge density wave (CDW) is oriented along [110] or [1-10] directions. We suggest that shear strains due to internal electric fields in the growth direction are responsible for the observed orientation of CDW in pristine electron and hole samples.Comment: 10 pages, 3 figure

A simple mathematical model of mosquito’s dynamics at stationary environmental conditions

Mathematical model of population dynamics with two types of individuals (mosquitoes which are malaria transmission vectors, and mosquitoes which are not transmission vectors) is under consideration. Some of basic properties of model were determined. Numerical analysis allowed obtaining typical dynamic regime

Transhumanism and posthumanism: dehumanization plans

The article analyzes the ideas of transhumanism and posthumanism, which appeal to new discoveries in the field of biomedical, information, cognitive and nanotechnology (NBIC-convergent technologies) in order to declare the possibility of their application in the issue of human «improvement». The relevance of the study lies in the fact that human transgression is carried out in line with the analyzed lines of thought, which indicates their anti-humanistic nature. This requires study, reasoned criticism and an appeal to positive humanistic concepts as a counterweight to anti-humanism. In the mainstream of transhumanism, a person is understood not as a concept, but as a construct, as a certain set of properties and components with varying degrees of reliability and value. The human mind is considered the most valuable, while the biological organization of a person is defined as flawed, and therefore requires intervention and correction, and in the future, a person should generally give way to a posthuman. The article provides a reasoned criticism of these ideas. The purpose of the article is to identify both the positive and negative sides of transhumanism and posthumanism, as well as to criticize the methodological foundations of these areas of thought – technicism and reductionism. Posthumanism does not require setting the limits of the existence of human civilization, like transhumanism, but here a person is viewed from an anti-anthropocentric point of view, that is, as a being without value, and no different from everything that exists in the world. The article shows that such ideas contradict both ideas about the evolution of nature and ideas about society and the system of human values. It is unacceptable to dissolve a person in the world of things, plants and animals. This contradicts both the history of nature and the history of mankind. In this study, such research methods as the method of historical and philosophical analysis and the method of comparison are used. The novelty of the research consists in comparing the positions and basic ideas of transhumanism and posthumanism, which makes it possible to identify their continuity in the development of anti-humanistic attitudes and to give a reasoned criticism of these directions

Orbital Magnetism in the Ballistic Regime: Geometrical Effects

We present a general semiclassical theory of the orbital magnetic response of noninteracting electrons confined in two-dimensional potentials. We calculate the magnetic susceptibility of singly-connected and the persistent currents of multiply-connected geometries. We concentrate on the geometric effects by studying confinement by perfect (disorder free) potentials stressing the importance of the underlying classical dynamics. We demonstrate that in a constrained geometry the standard Landau diamagnetic response is always present, but is dominated by finite-size corrections of a quasi-random sign which may be orders of magnitude larger. These corrections are very sensitive to the nature of the classical dynamics. Systems which are integrable at zero magnetic field exhibit larger magnetic response than those which are chaotic. This difference arises from the large oscillations of the density of states in integrable systems due to the existence of families of periodic orbits. The connection between quantum and classical behavior naturally arises from the use of semiclassical expansions. This key tool becomes particularly simple and insightful at finite temperature, where only short classical trajectories need to be kept in the expansion. In addition to the general theory for integrable systems, we analyze in detail a few typical examples of experimental relevance: circles, rings and square billiards. In the latter, extensive numerical calculations are used as a check for the success of the semiclassical analysis. We study the weak-field regime where classical trajectories remain essentially unaffected, the intermediate field regime where we identify new oscillations characteristic for ballistic mesoscopic structures, and the high-field regime where the typical de Haas-van Alphen oscillations exhibit finite-size corrections. We address the comparison with experimental data obtained in high-mobility semiconductor microstructures discussing the differences between individual and ensemble measurements, and the applicability of the present model.Comment: 88 pages, 15 Postscript figures, 3 further figures upon request, to appear in Physics Reports 199

Eta photoproduction on the neutron at GRAAL: Measurement of the differential cross section

In this contribution, we will present our first preliminary measurement of the differential cross section for the reaction gamma+n->eta+n. Comparison of the reactions gamma+p->eta+p for free and bound proton (D2 target) will also be discussed.Comment: 6 pages, 4 figures, Proceedings of the 10th International Symposium on Meson-Nucleon Physics and the Structure of the Nucleon, August 29-September 4 2004, Beijing, Chin