Ro-vibrational Quenching of CO (\u3cem\u3ev\u3c/em\u3e = 1) by He Impact in a Broad Range of Temperatures: A Benchmark Study Using Mixed Quantum/Classical Inelastic Scattering Theory

The mixed quantum/classical approach is applied to the problem of ro-vibrational energy transfer in the inelastic collisions of CO(v = 1) with He atom, in order to predict the quenching rate coefficient in a broad range of temperatures 5 \u3c T \u3c 2500 K. Scattering calculations are done in two different ways: direct calculations of quenching cross sections and, alternatively, calculations of the excitation cross sections plus microscopic reversibility. In addition, a symmetrized average-velocity method of Billing is tried. Combination of these methods allows reproducing experiment in a broad range of temperatures. Excellent agreement with experiment is obtained at 400 \u3c T \u3c 2500 K (within 10%), good agreement in the range 100 \u3c T \u3c 400 K (within 25%), and semi-quantitative agreement at 40 \u3c T \u3c 100 K(within a factor of 2). This study provides a stringent test of the mixed quantum/classical theory, because the vibrational quantum in CO molecule is rather large and the quencher is very light (He atom). For heavier quenchers and closer to dissociation limit of the molecule, the mixed quantum/classical theory is expected to work even better

Channeling of electrons and positrons in straight and periodically bent diamond(110) crystals

In this paper we present the results of a systematic numerical analysis of the channeling properties of electrons and positrons in oriented straight and periodically bent diamond(110) crystals. We analyse dependence of the intensity of the radiation emitted on the projectile energy as well as on the bending amplitude. The analysis presented is based on the grounds of accurate numerical simulations of the channeling process. The simulation parameters, such as the crystal orientation, thickness and bending parameters of the crystals as well as the energy of the projectiles, were chosen to match those used in past and ongoing experiments. The peculiarities which appear in the radiation spectra are attributed to the interplay of various radiation mechanisms. The analysis performed can be used to predict and explain future experimental results.Comment: 14 pages, 8 figures, 1 tabl

Counting free fermions on a line: a Fisher-Hartwig asymptotic expansion for the Toeplitz determinant in the double-scaling limit

We derive an asymptotic expansion for a Wiener-Hopf determinant arising in the problem of counting one-dimensional free fermions on a line segment at zero temperature. This expansion is an extension of the result in the theory of Toeplitz and Wiener-Hopf determinants known as the generalized Fisher-Hartwig conjecture. The coefficients of this expansion are conjectured to obey certain periodicity relations, which renders the expansion explicitly periodic in the "counting parameter". We present two methods to calculate these coefficients and verify the periodicity relations order by order: the matrix Riemann-Hilbert problem and the Painleve V equation. We show that the expansion coefficients are polynomials in the counting parameter and list explicitly first several coefficients.Comment: 11 pages, minor corrections, published versio

Characterizing correlations with full counting statistics: classical Ising and quantum XY spin chains

We propose to describe correlations in classical and quantum systems in terms of full counting statistics of a suitably chosen discrete observable. The method is illustrated with two exactly solvable examples: the classical one-dimensional Ising model and the quantum spin-1/2 XY chain. For the one-dimensional Ising model, our method results in a phase diagram with two phases distinguishable by the long-distance behavior of the Jordan-Wigner strings. For the quantum XY chain, the method reproduces the previously known phase diagram.Comment: 6 pages, section on Lee-Yang zeros added, published versio

Urgent Computing for Operational Storm Surge Forecasting in Saint-Petersburg

AbstractThe accurate forecasting of storm surges and decision support for gates maneuvering is an important issue in Saint-Petersburg. The evolution of the numerical hydrodynamic models, hardware performance and computer technologies allow to make Flood Warning System (FWS) in Saint-Petersburg more reliable and appropriate to the real needs. This article describes the key solutions of the development and the present operational set-up of FWS with emphasis on computational issues and decision support on the basis of urgent computing paradigm. It includes a brief description data-assimilation techniques, such as Kalman filtering, the probabilistic real-data forecasting model, forecast quality control, distributed computing of different scenarios and decision support for gates maneuvering

Workflow-based Collaborative Decision Support for Flood Management Systems

AbstractSimulation-based decision making is the one of prospective applications of computational sciences which is central to advances in many scientific fields. The complexity and interdisciplinarity of scientific problems lead to the new technologies of simulation software implementation based on cloud computing, workflow tools and close interaction between experts and decision-makers. The important challenge in this field is to combine simulation scenarios, expert decisions and distributed environment to solve the complex interdisciplinary problems. In this paper, we describe a way to organize the collaborative decision support on the basis of e-Science platform CLAVIRE with the emphasis on urgency. A case study on decision making is the gates maneuvering for the flood prevention in Saint-Petersburg as a part of flood management system

Oxidative stress in infection and consequent disease

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