1,269 research outputs found

    Регулирование информационного взаимодействия государственных органов с гражданами и организациями Украины

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    The system of a uniform information support of authorities and local management units is the integral part of information society and "E-government" of Ukraine. Its main objective is to provide efficiency for collection of information, creation of information resources, access to the information of authorities and the citizens, rise of efficiency of accepted solutions, support of information interactions of authorities; rendering real services from the state authorities to its citizens. Creation of such a system calls for enforcement issues inside the state bodies of the defined functions, development projects to define the rules in using interaction with citizens, implementations of the methods of process concepts and analysis of economic and social information

    Parameterization invariance and shape equations of elastic axisymmetric vesicles

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    The issue of different parameterizations of the axisymmetric vesicle shape addressed by Hu Jian-Guo and Ou-Yang Zhong-Can [ Phys.Rev. E {\bf 47} (1993) 461 ] is reassesed, especially as it transpires through the corresponding Euler - Lagrange equations of the associated elastic energy functional. It is argued that for regular, smooth contours of vesicles with spherical topology, different parameterizations of the surface are equivalent and that the corresponding Euler - Lagrange equations are in essence the same. If, however, one allows for discontinuous (higher) derivatives of the contour line at the pole, the differently parameterized Euler - Lagrange equations cease to be equivalent and describe different physical problems. It nevertheless appears to be true that the elastic energy corresponding to smooth contours remains a global minimum.Comment: 10 pages, latex, one figure include

    Short-time dynamics and magnetic critical behavior of two-dimensional random-bond Potts model

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    The critical behavior in the short-time dynamics for the random-bond Potts ferromagnet in two-dimensions is investigated by short-time dynamic Monte Carlo simulations. The numerical calculations show that this dynamic approach can be applied efficiently to study the scaling characteristic, which is used to estimate the critical exponents theta, beta/nu and z for the quenched disorered systems from the power-law behavior of the kth moments of magnetizations.Comment: 10 pages, 4 figures Soft Condensed Matte

    Approximate Particle Number Projection for Rotating Nuclei

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    Pairing correlations in rotating nuclei are discussed within the Lipkin-Nogami method. The accuracy of the method is tested for the Krumlinde-Szyma\'nski R(5) model. The results of calculations are compared with those obtained from the standard mean field theory and particle-number projection method, and with exact solutions.Comment: 15 pages, 6 figures available on request, REVTEX3.

    A modeling approach shows the effects of different light-dark schemes on the entrainment ability of the suprachiasmatic nucleus

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    In mammals, an endogenous clock located in the suprachiasmatic nucleus (SCN), synchronizes physiological and biological rhythms to the environmental light–dark cycle. In experiments, most researchers applied rectangular scheme as the external light–dark scheme received by the SCN neuronal oscillators. However, the external light intensity changes gradually throughout the day. Therefore, trapezoidal schemes (twilight) or sinusoidal schemes were also applied. Thus far, the effects of different light–dark schemes on the oscillators of the SCN did not get fully explored. In the present study, we theoretically analyzed how the five common light–dark schemes affect the entrainment ability of the SCN, based on a Poincaré model. We numerically found that when the maximum light intensity, the minimum light intensity, and the total amount of light exposure per cycle were the same, the largest entrainment range was obtained in the oscillators receiving more light in the daytime. However if, under the condition of 12:12-h illumination, the total amount of light exposure per cycle was the same, the maximum light intensity during the day leaded to an increased range of entrainment. Moreover, the entrainment range was reduced when the photoperiod was extended. Note that, increasing the maximum light intensity increased the entrainment ability of all light–dark schemes. Our results exposes the important role of light–dark schemes in the entrainment ability of the SCN network, and provides a potential explanation for the diversity of the entrainment range between diurnal and nocturnal animals. Circadian clocks in health and diseas

    Approximate particle number projection for finite range density dependent forces

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    The Lipkin-Nogami method is generalized to deal with finite range density dependent forces. New expressions are derived and realistic calculations with the Gogny force are performed for the nuclei 164^{164}Er and 168^{168}Er. The sharp phase transition predicted by the mean field approximation is washed out by the Lipkin-Nogami approach; a much better agreement with the experimental data is reached with the new approach than with the Hartree-Fock_Bogoliubov one, specially at high spins.Comment: 5 pages, RevTeX 3.0, 3 postscript figures included using uufiles. Submitted to Phys. Rev. Let

    Molecular Dynamics Simulation of Semiflexible Polyampholyte Brushes - The Effect of Charged Monomers Sequence

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    Planar brushes formed by end-grafted semiflexible polyampholyte chains, each chain containing equal number of positively and negatively charged monomers is studied using molecular dynamics simulations. Keeping the length of the chains fixed, dependence of the average brush thickness and equilibrium statistics of the brush conformations on the grafting density and the salt concentration are obtained with various sequences of charged monomers. When similarly charged monomers of the chains are arranged in longer blocks, the average brush thickness is smaller and dependence of brush properties on the grafting density and the salt concentration is stronger. With such long blocks of similarly charged monomers, the anchored chains bond to each other in the vicinity of the grafting surface at low grafting densities and buckle toward the grafting surface at high grafting densities.Comment: 8 pages,7 figure

    New quantum phase transitions in the two-dimensional J1-J2 model

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    We analyze the phase diagram of the frustrated Heisenberg antiferromagnet, the J1-J2 model, in two dimensions. Two quantum phase transitions in the model are already known: the second order transition from the Neel state to the spin liquid state at (J_2/J_1)_{c2}=0.38, and the first order transition from the spin liquid state to the collinear state at (J_2/J_1)_{c4}=0.60. We have found evidence for two new second order phase transitions: the transition from the spin columnar dimerized state to the state with plaquette type modulation at (J_2/J_1)_{c3}=0.50(2), and the transition from the simple Neel state to the Neel state with spin columnar dimerization at (J_2/J_1)_{c1}=0.34(4). We also present an independent calculation of (J_2/J_1)_{c2}=0.38 using a new approach.Comment: 3 pages, 5 figures; added referenc

    A frustrated quantum spin-{\boldmath s} model on the Union Jack lattice with spins {\boldmath s>1/2}

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    The zero-temperature phase diagrams of a two-dimensional frustrated quantum antiferromagnetic system, namely the Union Jack model, are studied using the coupled cluster method (CCM) for the two cases when the lattice spins have spin quantum number s=1s=1 and s=3/2s=3/2. The system is defined on a square lattice and the spins interact via isotropic Heisenberg interactions such that all nearest-neighbour (NN) exchange bonds are present with identical strength J1>0J_{1}>0, and only half of the next-nearest-neighbour (NNN) exchange bonds are present with identical strength J2κJ1>0J_{2} \equiv \kappa J_{1} > 0. The bonds are arranged such that on the 2×22 \times 2 unit cell they form the pattern of the Union Jack flag. Clearly, the NN bonds by themselves (viz., with J2=0J_{2}=0) produce an antiferromagnetic N\'{e}el-ordered phase, but as the relative strength κ\kappa of the frustrating NNN bonds is increased a phase transition occurs in the classical case (ss \rightarrow \infty) at κccl=0.5\kappa^{\rm cl}_{c}=0.5 to a canted ferrimagnetic phase. In the quantum cases considered here we also find strong evidence for a corresponding phase transition between a N\'{e}el-ordered phase and a quantum canted ferrimagnetic phase at a critical coupling κc1=0.580±0.015\kappa_{c_{1}}=0.580 \pm 0.015 for s=1s=1 and κc1=0.545±0.015\kappa_{c_{1}}=0.545 \pm 0.015 for s=3/2s=3/2. In both cases the ground-state energy EE and its first derivative dE/dκdE/d\kappa seem continuous, thus providing a typical scenario of a second-order phase transition at κ=κc1\kappa=\kappa_{c_{1}}, although the order parameter for the transition (viz., the average ground-state on-site magnetization) does not go to zero there on either side of the transition.Comment: 1
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