Floquet-Liouville supermatrix approach: Time development of density-matrix operator and multiphoton resonance fluorescence spectra in intense laser fields

This is the publisher's version, also available electronically from http://journals.aps.org/pra/abstract/10.1103/PhysRevA.33.1798.A Floquet-Liouville supermatrix (FLSM) approach is presented for nonperturbative treatment of the time development of the density-matrix operator of atoms and molecules exposed to intense polychromatic fields. By extending the many-mode Floquet theory (MMFT) recently developed, the time-dependent Liouville equation for the density matrix of quantum systems undergoing relaxations (due to radiative decays and collisional dampings, etc.) can be transformed into an equivalent time-independent non-Hermitian FLSM eigenvalue problem. This yields a numerically stable and computationally efficient approach for the unified treatment of nonresonant and resonant, one- and multiple-photon, steady-state and transient phenomena in nonlinear optical processes, much beyond the conventional rotating-wave-approximation (RWA) method. Connections of the FLSM approach to the MMFT in the limit of zero relaxations are also made, providing the understanding of the physical significance of FLSM supereigenvalues and eigenvectors. In addition to the exact FLSM formalism, we have also presented higher-order perturbative results, based on the extension of the generalized Van Vleck (GVV) nearly degenerate perturbation theory, appropriate for somewhat weaker fields and near-resonant processes, but beyond the RWA limit. The implementation of the GVV method in the time-independent Floquet-Liouvillian allows the reduction of the infinite-dimensional FLSM into a finite-dimensional GVV-Liouville matrix, from which essential analytical results are readily obtained. As an illustration of the usefulness of the new formalism, we extend both the FLSM and the GVV methods to a formal study of the multiphoton-induced resonance fluorescence spectra of two-level systems subject to purely radiation relaxations. Both the time-averaged power spectrum and the time-dependent physical spectrum are exploited in details, and novel new features in intense fields are pointed out

A STUDY OF THE INFLUENCES OF KNOWLEDGE BOUNDARY SPANNING ON PROJECT PERFORMANCE IN INFORMATION SYSTEM DEVELOPMENT PROJECTS

Information system development (ISD) is a knowledge intensive process, and a socialize cross-disciplines collaboration that brings up innovations and creates a competitive advantage for the organization. However, different layers of knowledge boundaries (syntactic, semantic, pragmatic) arise with the knowledge diversity of the ISD project and further lowers the project performance and product quality. To solve the problems, we will follow a construct development methodology to empirically identify the critical knowledge boundary spanning (KBS) processes, roles and objects for different layers of knowledge boundary, examine their influences to the effectiveness of corresponding KBS, and further assess the direct and moderating relationships from KBS effectiveness to project performance and product quality through a questionnaire survey. For academic applications, we not only split up the layers of KBS effectiveness and examine their direct and moderating effects to ISD performance but also offer categorized KBS activities under a formal construct development methodology for future studies. For practical implications, we offer a model for ISD team members to refer to for solving their knowledge boundary issues and increase their project performance and product quality

Intensification of Premonsoon Tropical Cyclones in the Bay of Bengal and Its Impacts on Myanmar

We analyze multiple global reanalysis and precipitation datasets in order to explain the dynamic mechanisms that lead to an observed intensification of the monsoon trough and associated tropical cyclone (TC) activity over the Bay of Bengal (BOB) during the premonsoon month of May. We find that post-1979 increases in both premonsoon precipitation and TC intensity are a result of enhanced large-scale monsoon circulation, characterized by lower-level cyclonic and upper-level anticyclonic anomalies. Such circulation anomalies are manifest of the tropospheric expansion that is caused by regional warming. The deepened monsoon trough in the BOB not only affects TC frequency and timing, but also acts to direct more cyclones towards Myanmar. We propose that increasing sea surface temperature in the BOB has contributed to an increase in cyclone intensity. Our analyses of the Community Earth System Model single-forcing experiments suggest that tropospheric warming and a deepening of the monsoon trough can be explained by two discreet anthropogenic causes--an increase in absorption due to aerosol loading and an increase in the land-ocean thermal contrast that results from increased greenhouse gases. The ensuing circulation changes provide favorable conditions for TCs to grow and to track eastward towards Myanmar

Homogeneous point mutation detection by quantum dot-mediated two-color fluorescence coincidence analysis

This report describes a new genotyping method capable of detecting low-abundant point mutations in a homogeneous, separation-free format. The method is based on integration of oligonucleotide ligation with a semiconductor quantum dot (QD)-mediated two-color fluorescence coincidence detection scheme. Surface-functionalized QDs are used to capture fluorophore-labeled ligation products, forming QD-oligonucleotide nanoassemblies. The presence of such nanoassemblies and thereby the genotype of the sample is determined by detecting the simultaneous emissions of QDs and fluorophores that occurs whenever a single nanoassembly flows through the femtoliter measurement volume of a confocal fluorescence detection system. The ability of this method to detect single events enables analysis of target signals with a multiple-parameter (intensities and count rates of the digitized target signals) approach to enhance assay sensitivity and specificity. We demonstrate that this new method is capable of detecting zeptomoles of targets and achieve an allele discrimination selectivity factor >10(5)

An Extension of the Direct Method for Verifying Programs

A direct method based on a finite set of path formulas which describe the input-output relations of a given program can be used to verify programs containing no overlapping loops. One major difficulty in verifying programs with overlapping loops using the above method is that too many path formulas (possibly infinite) needed to be considered. In this paper, we circumvent the above difficulty by applying the concept of modularity. The idea is to divide a program with overlapping loops into several small modules so that each module contains no overlapping loop. This can always be achieved if the program is in structured form. Then the path formulas will be derived for each module. By combining the path formulas for the modules, one can further obtain the path formulas for the given program and then use them to verify the program