579 research outputs found

    Организация и ведение поисково и аварийно-спасательных работ на водоемах

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    Проведение поисковых и аварийно-спасательных работ на воде с применением спасательных судов при возникновении чрезвычайных ситуаций является одной из основных задач Единой государственной системы предупреждения и ликвидации чрезвычайных ситуаций (РСЧС), позволяющих уменьшить жертвы и сохранить здоровье людей. Спасение терпящих бедствие на воде должно быть организовано своевременно, оперативно и комплексно, то есть в полном объеме по всём необходимым в конкретной обстановке видам работ по спасению пострадавших.Conducting search and rescue operations on the water with the use of rescue vessels in the event of emergencies is one of the main tasks of the Unified State System for the Prevention and Elimination of Emergencies (RSES), which makes it possible to reduce casualties and preserve people's health. Salvation of those in distress on the water must be organized in a timely manner, promptly and in a comprehensive manner, that is, in full volume for all kinds of rescue work for the victims

    Chlorin Index: A new parameter for organic matter freshness in sediments

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    Total chlorins, comprising degradation products of chlorophyll, have been used recently to reconstruct paleoproductivity from marine sediment cores. Here, we report on a new index, the Chlorin Index (CI), that proves to be a helpful tool for rapidly estimating organic matter freshness in marine sediments. The CI is a ratio between the fluorescence intensity of a sediment extracted with acetone and treated with hydrochloric acid and the original sediment extract. It represents the ratio of chlorophyll and its degradation products deposited in the sediments that could still be chemically transformed and those that are inert to chemical attack. The ratio is lower in sediments that include freshly deposited phytoplankton material and higher in older, more degraded sediments. We measured this new parameter on surface sediments, and sediments from several short and a long sediment core from different oceanic settings. CI values range from 0.2 for chlorophyll a to 0.36–0.56 for fresh material deposited on the shelf off Namibia to values around 0.67 in sediments off Chile and Peru to values up to 0.97 for sediments in a deep core from the northeastern slope of the Arabian Sea. We have compared the CI to rates of bacterial sulfate reduction, as a direct measure of organic matter reactivity and to other degradation indices based on amino acid composition. We conclude that the CI is a reliable and simple tool for the characterization of organic material freshness in sediments in respect to its degradation state

    Stripe Ansatzs from Exactly Solved Models

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    Using the Boltzmann weights of classical Statistical Mechanics vertex models we define a new class of Tensor Product Ansatzs for 2D quantum lattice systems, characterized by a strong anisotropy, which gives rise to stripe like structures. In the case of the six vertex model we compute exactly, in the thermodynamic limit, the norm of the ansatz and other observables. Employing this ansatz we study the phase diagram of a Hamiltonian given by the sum of XXZ Hamiltonians along the legs coupled by an Ising term. Finally, we suggest a connection between the six and eight-vertex Anisotropic Tensor Product Ansatzs, and their associated Hamiltonians, with the smectic stripe phases recently discussed in the literature.Comment: REVTEX4.b4 file, 10 pages, 2 ps Figures. Revised version to appear in PR

    A new family of matrix product states with Dzyaloshinski-Moriya interactions

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    We define a new family of matrix product states which are exact ground states of spin 1/2 Hamiltonians on one dimensional lattices. This class of Hamiltonians contain both Heisenberg and Dzyaloshinskii-Moriya interactions but at specified and not arbitrary couplings. We also compute in closed forms the one and two-point functions and the explicit form of the ground state. The degeneracy structure of the ground state is also discussed.Comment: 15 pages, 1 figur

    Matrix Product Ground States for Asymmetric Exclusion Processes with Parallel Dynamics

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    We show in the example of a one-dimensional asymmetric exclusion process that stationary states of models with parallel dynamics may be written in a matrix product form. The corresponding algebra is quadratic and involves three different matrices. Using this formalism we prove previous conjectures for the equal-time correlation functions of the model.Comment: LaTeX, 8 pages, one postscript figur

    Stochastic Models on a Ring and Quadratic Algebras. The Three Species Diffusion Problem

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    The stationary state of a stochastic process on a ring can be expressed using traces of monomials of an associative algebra defined by quadratic relations. If one considers only exclusion processes one can restrict the type of algebras and obtain recurrence relations for the traces. This is possible only if the rates satisfy certain compatibility conditions. These conditions are derived and the recurrence relations solved giving representations of the algebras.Comment: 12 pages, LaTeX, Sec. 3 extended, submitted to J.Phys.

    Mixed-spin systems: coexistence of Haldane gap and antiferromagnetic long range order

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    Recent experiments on the quasi-1D antiferromagnets R2BaNiO5R_{2}BaNiO_{5} (R = rare earth) have shown the existence of purely 1D Haldane gap excitations propagating on the Ni chains. Below an ordering temperature, the gap excitations survive and coexist with the conventional spin waves in the ordered phase. We construct a model mixed-spin system in 2D for which the ground state can be exactly specified. Using the Matrix Product Method, we show the existence of Haldane gap excitations in the ordered phase. We consider different cases of ordering to study the effect of ordering on the degeneracy of the Haldane gap excitations.Comment: 13 pages, LaTeX, 2 Postscript figures, communicated to Phys. Rev.

    A Density Matrix Algorithm for 3D Classical Models

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    We generalize the corner transfer matrix renormalization group, which consists of White's density matrix algorithm and Baxter's method of the corner transfer matrix, to three dimensional (3D) classical models. The renormalization group transformation is obtained through the diagonalization of density matrices for a cubic cluster. A trial application for 3D Ising model with m=2 is shown as the simplest case.Comment: 15 pages, Latex(JPSJ style files are included), 8 ps figures, submitted to J. Phys. Soc. Jpn., some references are correcte

    Alternating-Spin Ladders

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    We investigate a two-leg spin ladder system composed of alternating-spin chains with two-different kind of spins. The fixed point properties are discussed by using spin-wave analysis and non-linear sigma model techniques. The model contains various massive phases, reflecting the interplay between the bond-alternation and the spin-alternation.Comment: 6 pages, revtex, to appear in PR

    Multi-plateau magnetization curves of one-dimensional Heisenberg ferrimagnets

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    Ground-state magnetization curves of ferrimagnetic Heisenberg chains of alternating spins SS and ss are numerically investigated. Calculating several cases of (S,s)(S,s), we conclude that the spin-(S,s)(S,s) chain generally exhibits 2s2s magnetization plateaux even at the most symmetric point. In the double- or more-plateau structure, the initial plateau is generated on a classical basis, whereas the higher ones are based on a quantum mechanism.Comment: 6 pages, 6 figures embedded, to appear in Phys. Rev. B 01 August 200
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