Fast algorithm for calculating two-photon absorption spectra

We report a numerical calculation of the two-photon absorption coefficient of electrons in a binding potential using the real-time real-space higher-order difference method. By introducing random vector averaging for the intermediate state, the task of evaluating the two-dimensional time integral is reduced to calculating two one-dimensional integrals. This allows the reduction of the computation load down to the same order as that for the linear response function. The relative advantage of the method compared to the straightforward multi-dimensional time integration is greater for the calculation of non-linear response functions of higher order at higher energy resolution.Comment: 4 pages, 2 figures. It will be published in Phys. Rev. E on 1, March, 199

Collagen adhesion gene is associated with blood stream infections caused by methicillin-resistant Staphylococcus aureus

Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) causes hospital- and community-acquired infections. It is not clear whether genetic characteristics of the bacteria contribute to disease pathogenesis in MRSA infection. We hypothesized that whole genome analysis of MRSA strains could reveal the key gene loci and/or the gene mutations that affect clinical manifestations of MRSA infection. Methods: Whole genome sequences (WGS) of MRSA of 154 strains were analyzed with respect to clinical manifestations and data. Further, we evaluated the association between clinical manifestations in MRSA infection and genomic information. Results: WGS revealed gene mutations that correlated with clinical manifestations of MRSA infection. Moreover, 12 mutations were selected as important mutations by Random Forest analysis. Cluster analysis revealed strains associated with a high frequency of bloodstream infection (BSI). Twenty seven out of 34 strains in this cluster caused BSI. These strains were all positive for collagen adhesion gene (cna) and have mutations in the locus, those were selected by Random Forest analysis. Univariate and multivariate analysis revealed that these gene mutations were the predictor for the incidence of BSI. Interestingly, mutant CNA protein showed lower attachment ability to collagen, suggesting that the mutant protein might contribute to the dissemination of bacteria. Conclusions: These findings suggest that the bacterial genotype affects the clinical characteristics of MRSA infection. (c) 2019 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases

3. Magnetoresistance in Anderson Localized Regime(Theories,I. Three Dimensional Systems)

この論文は国立情報学研究所の電子図書館事業により電子化されました。Magnetoresistance in the Anderson-localized regime is calculated by the percolation method, with a particular purpose of investigating the effects of electron-electron interaction on it. It is predicted that the interplay of the intrastate interaction and the energy dependence of localization lengths gives rise to the competition of positive and negative contributions in the field dependence of the magnetoresistance. Further, combined with the interstate interactions, the temperature change in the magnetoresistance of 1T-TaS_2 and its alloy systems is explained satisfactorily. Finally the correlation of the interaction effects on the variable range hopping in the absence and presence of a magnetic field is clarified

Transient Behaviour Simulation of Excitons Created by a Train of Two Ultrashort Laser Pulses II

We continue the study of transient behavior of Excitons. This presentation follows the previous one at PCW'95-Japan[1][2]. Carriers undergo various thermal relaxation processes after they are excited in a semiconductor by femtosecond laser pulses. Since Coulomb interaction is most eective immediately after excitation, we treat it to high orders within the framework of RPA (Random Phase Approximation). We use Non-equilibrium Green's function method as before, and solve Dyson's equation numerically on a pararell computer(AP1000). 1 Introduction Recent development of laser technique has enabled us to generate ultrashort laser pulses, and thus examine non-equilibrium phenomena of carriers in semiconductors at ultra-short time range. In such applications as designing ultrahigh speed switching devices, it is important to investigate the transient behavior of carriers. At present, however, theoretical study of this problem hasn't caught up with experiments[3]. We are investigating transient..