Rate coefficients for rovibrational transitions in H_2 due to collisions with He

We present quantum mechanical and quasiclassical trajectory calculations of cross sections for rovibrational transitions in ortho- and para-H_2 induced by collisions with He atoms. Cross sections were obtained for kinetic energies between 10^-4 and 3 eV, and the corresponding rate coefficients were calculated for the temperature range 100<T<4000 K. Comparisons are made with previous calculations.Comment: 21 pages, 2 figures, AAS, eps

Precedence-type Test based on Progressively Censored Samples

In this paper, we introduce precedence-type tests for testing the hypothesis that two distribution functions are equal, which is an extension of the precedence life-test rst proposed by Nelson (1963), when the two samples are progressively Type-II censored. The null distributions of the test statistics are derived. Critical values for some combination of sample sizes and censoring schemes for the proposed tests are presented. Then, we present the exact power functions under the Lehmann alternative, and compare the exact power as well as simulated power (under location-shift) of the proposed precedence test based on nonparametric estimates of CDF with other precedence-type tests. We then examine the power properties of the proposed test procedures through Monte Carlo simulations. Two examples are presented to illustrate all the test procedures discussed here. Finally, we make some concluding remarks.Precedence test; Product-limit estimator; Type-II progressive censoring; Life-testing; level of significance; power; Lehmann alternative; Monte Carlo simulations

Studies on nucleotidases in plants: isolation and properties of the monomeric form of the crystalline and homogeneous mung bean nucleotide pyrophosphatase

Mung bean nucleotide pyrophosphatase isolated in a crystalline and homogeneous form as a dimer with a molecular weight of 65000 was converted by AMP into a tetramer. The tetramer was enzymatically active with altered kinetic properties. This conversion of the dimeric form by AMP to a tetrameric one was prevented by treating the dimer with p-hydroxymercuribenzoate. The molecular weight of the p-hydroxymercuribenzoate-treated enzyme was determined to be 32700 by a combination of Stokes' radius (2.4 nm) and sedimentation velocity (S20,w = 1.9 S), by thin-layer gel chromatography on superfine Sephadex G-200 and by sodium dodecylsulfate/polyacrylamide gel electrophoresis. The monomer obtained by treatment of the native enzyme with p-hydroxymercuribenzoate was isolated by passage of the dissociated enzyme through a column of Biogel P-200. The monomer was optimally active at 37&#176;C, whereas the dimer and tetramer were active at 49&#176;C. All the three enzyme forms were maximally active at pH 9.4. The Km and V (measured as rate of FAD hydrolysis per mg protein) for FAD of the three enzyme forms were for the monomer, 0.5mM and 7.0 &#956;molmin-1, for the dimer, 0.25mM and 3.3 &#956;molmin-1 and for the tetramer, 0.58mM and 2.5 &#956;molmin-1, respectively. The time course of the reaction of the monomer was linear and comparable to the initial fast rate of the dimer. The monomer was not converted to a tetramer or a dimer on the addition of AMP; and it was irreversibly inhibited by urea and EDTA. ATP and ADP were noncompetitive inhibitors of the monomer

Experimental Implementation of Adaptive-Critic Based Infinite Time Optimal Neurocontrol for a Heat Diffusion System

Recently the synthesis methodology for the infinite time optimal neuro-controllers for PDE systems in the framework of adaptive-critic design has been developed. In this paper, first we model an experimental setup representing one dimensional heat diffusion problems. Then we synthesize and implement an adaptive-critic based neuro-controller for online temperature profile control of the experimental setup

State-to-state rotational transitions in H2_2+H2_2 collisions at low temperatures

We present quantum mechanical close-coupling calculations of collisions between two hydrogen molecules over a wide range of energies, extending from the ultracold limit to the super-thermal region. The two most recently published potential energy surfaces for the H$_2$-H$_2$ complex, the so-called DJ (Diep and Johnson, 2000) and BMKP (Boothroyd et al., 2002) surfaces, are quantitatively evaluated and compared through the investigation of rotational transitions in H$_2$+H$_2$ collisions within rigid rotor approximation. The BMKP surface is expected to be an improvement, approaching chemical accuracy, over all conformations of the potential energy surface compared to previous calculations of H$_2$-H$_2$ interaction. We found significant differences in rotational excitation/de-excitation cross sections computed on the two surfaces in collisions between two para-H$_2$ molecules. The discrepancy persists over a large range of energies from the ultracold regime to thermal energies and occurs for several low-lying initial rotational levels. Good agreement is found with experiment (Mat\'e et al., 2005) for the lowest rotational excitation process, but only with the use of the DJ potential. Rate coefficients computed with the BMKP potential are an order of magnitude smaller.Comment: Accepted by J. Chem. Phy

Quantum Calculation of Inelastic CO Collisions with H. II. Pure Rotational Quenching of High Rotational Levels

Carbon monoxide is a simple molecule present in many astrophysical environments, and collisional excitation rate coefficients due to the dominant collision partners are necessary to accurately predict spectral line intensities and extract astrophysical parameters. We report new quantum scattering calculations for rotational deexcitation transitions of CO induced by H using the three-dimensional potential energy surface~(PES) of Song et al. (2015). State-to-state cross sections for collision energies from 10$^{-5}$ to 15,000~cm$^{-1}$ and rate coefficients for temperatures ranging from 1 to 3000~K are obtained for CO($v=0$, $j$) deexcitation from $j=1-45$ to all lower $j'$ levels, where $j$ is the rotational quantum number. Close-coupling and coupled-states calculations were performed in full-dimension for $j$=1-5, 10, 15, 20, 25, 30, 35, 40, and 45 while scaling approaches were used to estimate rate coefficients for all other intermediate rotational states. The current rate coefficients are compared with previous scattering results using earlier PESs. Astrophysical applications of the current results are briefly discussed.Comment: 8 figures, 1 tabl