Electronic and Structural Properties of C36_{36} Molecule

The extended SSH model and Bogoliubov-de Gennes(BdeG) formalism are applied to investigate the electronic properties and stable lattice configurations of C$_{36}$. We focus the problem on the molecule's unusual $D_{6h}$ symmetry. The electronic part of the Hamiltonian without Coulomb interaction is solved analytically. We find that the gap between HOMO and LUMO is small due to the long distance hopping between the 2nd and 5th layers. The charge densities of HOMO and LUMO are mainly distributed in the two layers, that causes a large splitting between the spin triplet and singlet excitons. The differences of bond lengths, angles and charge densities among the molecule and polarons are discussed.Comment: 15 pages, 4 figures, 4 Table

High-Order Object Model Based Software Analysis

The integration of object oriented modeling and structured analysis (SA) for developing a well structured object oriented software system is a challenge for requirements analysts and software designers. Some of the existing object oriented modeling techniques adopt approaches that are very different from SA, and others have clumsily stayed with SA after a few modifications. Our High Order Object Modeling Technique (HOOMT) however, attempts to strike a mean between both extremes while at the same time provides an effective modeling method. HOOMT consists of two models, the High Order Object Model and the Object Information Flow Model. By using the familiar divide and conquer concept and functional decomposition, our approach also ensures a less stressful migration of SA analysts to object oriented platforms. The paper introduces HOOMT, its concepts, and notations

Improving Simulation Efficiency of MCMC for Inverse Modeling of Hydrologic Systems with a Kalman-Inspired Proposal Distribution

Bayesian analysis is widely used in science and engineering for real-time forecasting, decision making, and to help unravel the processes that explain the observed data. These data are some deterministic and/or stochastic transformations of the underlying parameters. A key task is then to summarize the posterior distribution of these parameters. When models become too difficult to analyze analytically, Monte Carlo methods can be used to approximate the target distribution. Of these, Markov chain Monte Carlo (MCMC) methods are particularly powerful. Such methods generate a random walk through the parameter space and, under strict conditions of reversibility and ergodicity, will successively visit solutions with frequency proportional to the underlying target density. This requires a proposal distribution that generates candidate solutions starting from an arbitrary initial state. The speed of the sampled chains converging to the target distribution deteriorates rapidly, however, with increasing parameter dimensionality. In this paper, we introduce a new proposal distribution that enhances significantly the efficiency of MCMC simulation for highly parameterized models. This proposal distribution exploits the cross-covariance of model parameters, measurements and model outputs, and generates candidate states much alike the analysis step in the Kalman filter. We embed the Kalman-inspired proposal distribution in the DREAM algorithm during burn-in, and present several numerical experiments with complex, high-dimensional or multi-modal target distributions. Results demonstrate that this new proposal distribution can greatly improve simulation efficiency of MCMC. Specifically, we observe a speed-up on the order of 10-30 times for groundwater models with more than one-hundred parameters

Isolation and Characterization of Newly Emerging Coronaviruses in Acute Respiratory Tract Diseases of Cattle.

A total of 411 G clone cell-dependent virus strains recently were isolated from nasal, trachea and lung samples in etiological investigations of acute respiratory tract diseases of vaccinated cattle, including shipping fever pneumonia. The virus infectivity titers reached up to 1.2 x 10 7 plaque forming units per gram of lung tissues of fatal cases. These viral agents were isolated in the 1st G clone cell passage without trypsin enhancement, and induced cell fusion. They have a restricted hemagglutination pattern, agglutinating only rat and mouse erythrocytes. Majority of them has receptor-destroying enzyme activities. They are round and enveloped with a diameter of 80 nm. Based on these features and the site of infections, these virus isolates were identified as respiratory bovine coronaviruses (RBCV). The RBCV were previously not recognized to be associated with acute respiratory tract diseases of cattle. Tests on serum samples from RBCV-positive cattle during a shipping fever epizootic revealed characteristic primary immune responses with specific antibodies to hemagglutinin-esterase and spike. The RBCV-positive cattle that died had only IgM responses to RBCV infections. High level of opsonic and virus-neutralizing IgG2 apparently protected cattle from RBCV infections and respiratory tract disease. These cattle entered this experiment with high antibodies against hemagglutinin-esterase and spike. The G clone cells had maximal susceptibility to RBCV infections from apical domains. Asymmetric release of RBCV occurred through the apical surfaces of the cells. The RBCV-induced polykaryons had intact plasma membranes and degenerated nuclei and resulted from expression of spike on cytoplasmic membrane and RBCV replication, indicating fusion from within. The purified RBCV particles showed higher acetylesterase activity at 37°C than at 39°C, while the purified enteropathogenic BCV (EBCV) particles retained full acetylesterase activity at both 37°C and 39°C. Transiently expressed hemagglutinin-esterase of RBCV exhibited a drastic reduction in acetylesterase activity after 40 min at 37°C while the acetylesterase activity of the transiently expressed hemagglutinin-esterase of EBCV remained stable beyond the 40 min threshold. The deduced amino acid sequences of hemagglutinin-esterase specified by RBCV strains contained specific amino acid changes in comparison to the wild-type EBCV strain, which may be responsible for the observed enzymatic differences