8,251 research outputs found
Ultracold collisions between two light indistinguishable diatomic molecules: elastic and rotational energy transfer in HD+HD
A close coupling quantum-mechanical calculation is performed for rotational
energy transfer in a HD+HD collision at very low energy, down to the ultracold
temperatures: K. A global six-dimensional H-H
potential energy surface is adopted from a previous work [Boothroyd {\it et
al.}, J. Chem. Phys., {\bf 116}, 666 (2002).] State-resolved integral cross
sections of different
quantum-mechanical rotational transitions in the HD
molecules and corresponding state-resolved thermal rate coefficients
have been computed. Additionally, for comparison,
H+H calculations for a few selected rotational transitions have also
been performed. The hydrogen and deuterated hydrogen molecules are treated as
rigid rotors in this work. A pronounced isotope effect is identified in the
cross sections of these collisions at low and ultracold temperatures.Comment: 9 pages, 9 figures. Accepted for publication in Physical Review
Low-energy three-body charge transfer reactions with Coulomb interaction in the final state
Three-body charge transfer reactions with Coulomb interaction in the final
state are considered in the framework of coordinate-space integro-differential
Faddeev-Hahn-type equations within two- and six-state close coupling
approximations. The method is employed to study direct muon transfer in
low-energy collisions of the muonic hydrogen H by helium (He) and
lithium (Li) nuclei. The experimentally observed isotopic dependence is
reproduced.Comment: 14 pages REVTeX, accepted for publication in Journal of Physics
Low-energy direct muon transfer from H to Ne, S and Ar using two-state close-coupling approximation to Faddeev-Hahn-type equation
We perform three-body calculation of direct muon-transfer rates from thermalized muonic hydrogen isotopes to bare nuclei Ne, S, and Ar employing integro-differential Faddeev-Hahn-type equations in configuration space with two-state close-coupling approximation scheme. All Coulomb potentials including the strong final-state Coulomb repulsion are treated exactly. A long-range polarization potential is included in the elastic channel to take into account the high polarizability of the muonic hydrogen. The transfer rates so calculated are in good agreement with recent experiments. We find that the muon is captured predominantly in the , 9, and 10 states of muonic Ne, S, and Ar, respectively
Dynamical calculation of direct muon-transfer rates from thermalized muonic hydrogen to C^{6+} and O^{8+}
We perform dynamical calculations of direct muon-transfer rates from thermalized muonic hydrogen isotopes to bare nuclei C and O. For these three-body charge-transfer reactions with Coulomb interaction in the final state we use two-component integro-differential Faddeev-Hahn-type equations in configuration space using close-coupling approximation. To take into account the high polarizability of the muonic hydrogen due to the large charge of the incident nuclei, a polarization potential is included in the elastic channel. The large final-state Coulomb interaction is explicitly included in the transfer channel. The transfer rates so calculated are in good agreement with recent experiments
Memory efficient algorithm for solving the inverse gravimetry problem of finding several boundary surfaces in multilayered medium
For solving the inverse gravimetry problem of finding several boundary surfaces in a multilayered medium, the parallel algorithm was constructed and implemented for multicore CPU using OpenMP technology. The algorithm is based on the modified nonlinear conjugate gradient method with weighting factors previously proposed by authors. To reduce the memory requirements and computation time, the modification was constructed on the basis of utilizing the Toeplitz-block-Toeplitz structure of the Jacobian matrix of the integral operator. The model problem of reconstructing three surfaces using the quasi-real gravitational data was solved on a large grid. It was shown that the proposed implementation reduces the computation time by 80% in comparison with the earlier algorithm based on calculating the entire matrix. The parallel algorithm shows good scaling of 94% on 8-core processor. © 2019 Author(s).Ministry of Education and Science of the Republic of Kazakhstan: AP 05133873This work was financially supported by the Ministry of Education and Science of the Republic of Kazakhstan (project AP 05133873)
Separation of reservoir layers based on neuro-fuzzy systems
In the article, the application algorithms of neural network methods for determining the lithological composition of a well bore according to logging data are studied by training based on the analysis of the correspondence of logs to the available expert opinion. Specialized algorithms for processing the results of network operation have been developed to increase the information content of a signal produced by a neural network and to increase the reliability of recognition
The chemistry of vibrationally excited H2 in the interstellar medium
The internal energy available in vibrationally excited H2 molecules can be
used to overcome or diminish the activation barrier of various chemical
reactions of interest for molecular astrophysics. In this article we
investigate in detail the impact on the chemical composition of interstellar
clouds of the reactions of vibrationally excited H2 with C+, He+, O, OH, and
CN, based on the available chemical kinetics data. It is found that the
reaction of H2 (v>0) and C+ has a profound impact on the abundances of some
molecules, especially CH+, which is a direct product and is readily formed in
astronomical regions with fractional abundances of vibrationally excited H2,
relative to ground state H2, in excess of 10^(-6), independently of whether the
gas is hot or not. The effects of these reactions on the chemical composition
of the diffuse clouds zeta Oph and HD 34078, the dense PDR Orion Bar, the
planetary nebula NGC 7027, and the circumstellar disk around the B9 star HD
176386 are investigated through PDR models. We find that formation of CH+ is
especially favored in dense and highly FUV illuminated regions such as the
Orion Bar and the planetary nebula NGC 7027, where column densities in excess
of 10^(13) cm^(-2) are predicted. In diffuse clouds, however, this mechanism is
found to be not efficient enough to form CH+ with a column density close to the
values derived from astronomical observations.Comment: accepted for publication in the Astrophysical Journal; 9 pages, 7
figure
Predicting the solvation of organic compounds in aqueous environments: from alkanes and alcohols to pharmaceuticals
The development of accurate models to predict the solvation, solubility, and partitioning of nonpolar and amphiphilic compounds in aqueous environments remains an important challenge. We develop state-of-the-art group-interaction models that deliver an accurate description of the thermodynamic properties of alkanes and alcohols in aqueous solution. The group-contribution formulation of the statistical associating fluid theory based on potentials with a variable Mie form (SAFT-γ Mie) is shown to provide accurate predictions of the phase equilibria, including liquid–liquid equilibria, solubility, free energies of solvation, and other infinite-dilution properties. The transferability of the model is further exemplified with predictions of octanol–water partitioning and solubility for a range of organic and pharmaceutically relevant compounds. Our SAFT-γ Mie platform is reliable for the prediction of challenging properties such as mutual solubilities of water and organic compounds which can span over 10 orders of magnitude, while remaining generic in its applicability to a wide range of compounds and thermodynamic conditions. Our work sheds light on contradictory findings related to alkane–water solubility data and the suitability of models that do not account explicitly for polarity
Economic and health burden of brucellosis in Kazakhstan
Brucellosis is a widespread zoonotic disease considered as an emerging and re-emerging disease with a resulting threat of public health and animal health. Official reports document an animal incidence in Kazakhstan of about 0.6% per year, and the country still registers high number of human cases annually . The main objective of this paper was to evaluate the distribution and economic impact of brucellosis in Kazakhstan. We analysed human disease incidence data obtained from the Government Sanitary & Epidemiological Service with the aim to estimate the burden of disease in terms of disability-adjusted life years (DALYs). We also estimated the economic impact in terms of monetary losses. Additionally, we mapped the geographical distribution of the disease throughout Kazakhstan. In total, 1,334 human cases of brucellosis were registered in 2015 in Kazakhstan that resulted in 713 DALYs. Around US Dollar 21 million was spent on compensation for animals that had to be slaughtered due to brucellosis, and an additional US Dollar 24 million was spent on testing animals. Animal brucellosis and human brucellosis occur throughout the whole country, some trends of which are reviewed in this paper. We estimated the burden of the disease and explored possible explanation for high human incidence rates. This paper is the first to estimate the human burden of disease and the economic costs in Kazakhstan. Both of these are substantial
- …