716 research outputs found

    Intersecting D-brane states derived from the KP theory

    Full text link
    A general scheme to find tachyon boundary states is developed within the framework of the theory of KP hierarchy. The method is applied to calculate correlation function of intersecting D-branes and rederived the results of our previous works as special examples. A matrix generalization of this scheme provides a method to study dynamics of coincident multi D-branes.Comment: 10 page

    Physicochemical inactivation of zoonotic Viruses: Hemorrhagic fever with renal syndrome and lymphocytic choriomeningitis Viruses

    Get PDF
    To seek the most effective and practical methods of disinfecting and for inactivating two zoonotic viruses, hemorrhagic fever with renal syndrome virus (HFRSV) and lymphocytic choriomeningitis virus (LCMV), we analysed inactivation of the viruses by 8 commonly-used chemical disinfectants and physical treatments. The results demonstrated that alcohols (70% ethanol, 50% isopropanol), formaldehyde (2% formalin), quaternary ammonium chloride (0.05% benzalkonium chloride) and 1% saponated cresol were virucidal on more than 99.9% of the infectious virus particles. HFRSV was more resistant than LCMV on several treatments. No significant difference was observed in strains of HFRSV. Quaternary ammonium chloride and saponated cresol diluted with hot water (>60°C), are considered to be the reagents of choice for disinfecting the two zoonotic viruses because of their long-term effectiveness and mild corrosive action to metals. Spraying of alcohols has proven to be a suitable means for decontaminating instruments, and experiments tools in limited areas of animal laboratorie

    Post-event Processing Predicts Cortisol Recovery

    Get PDF
    There is growing evidence that individuals with social anxiety show impaired cortisol recovery after experiencing social evaluative stressors. Yet, little is known regarding the cognitive processes underlying such impaired cortisol recovery. The present study examined the effect of post-event processing (PEP), referred to as repetitive thinking about social situations, on cortisol recovery following a social stressor. Forty-two non-clinical university students (23 women, 19 men, mean age = 22.0 ± 2.0 years) completed the Trier Social Stress Test (TSST), followed by a thought sampling procedure which assessed the frequency of PEP reflecting the TSST. A growth curve model showed PEP and social anxiety interactively predicted cortisol recovery. In particular, PEP predicted impaired cortisol recovery in those with low levels of social anxiety but not in those with high levels of social anxiety, which contradicted the initial hypothesis. These findings suggest that PEP is differentially associated with cortisol recovery depending on levels of social anxiety. The possible mechanisms underlying these findings were discussed in terms of protective inhibition framework

    Allosteric Regulation of HIV-1 Reverse Transcriptase by ATP for Nucleotide Selection

    Get PDF
    Background: Human immunodeficiency virus type 1 reverse transcriptase (HIV-1 RT) is a DNA polymerase that converts viral RNA genomes into proviral DNAs. How HIV-1 RT regulates nucleotide selectivity is a central issue for genetics and the nucleoside analog RT inhibitor (NRTI) resistance of HIV-1. Methodology/Principal Findings: Here we show that an ATP molecule at physiological concentrations acts as an allosteric regulator of HIV-1 RT to decrease the Km value of the substrate, decrease the kcat value, and increase the Ki value of NRTIs for RT. Computer-assisted structural analyses and mutagenesis studies suggested the positions of the ATP molecule and NRTIresistance mutations during a catalytic reaction, which immediately predict possible influences on nucleotide insertion into the catalytic site, the DNA polymerization, and the excision reaction. Conclusions/Significance: These data imply that the ATP molecule and NRTI mutations can modulate nucleotide selectivity by altering the fidelity of the geometric selection of nucleotides and the probability of an excision reaction

    Urban Goods Transport of Medan: Basic Survey and Scenario Analysis

    Get PDF
    Abstract. This paper intends to propose a simple and effective methodology to collect urban goods transport data in developing cities and to analyze the urban policies based on the freight traffic flow model. As a case study, we surveyed the goods transport in Medan, Indonesia. We interviewed the related people, counted the traffic flows at major road accessing the CBD, and interviewed enterprises to collect the goods transport data. We estimated the freight traffic flow simulation model by synthesizing the collected data. Then, two land-use scenarios of the area where the airport is now located are discussed under the condition that the airport will be relocated. By applying the model, we found that the traffic volume and air pollution will increase when no countermeasure is taken in the commercial development scenario

    Identifying Characteristics of the Agile Development Process That Impact User Satisfaction

    Full text link
    The purpose of this study is to identify the characteristics of Agile development processes that impact user satisfaction. We used user reviews of OSS smartphone apps and various data from version control systems to examine the relationships, especially time-series correlations, between user satisfaction and development metrics that are expected to be related to user satisfaction. Although no metrics conclusively indicate an improved user satisfaction, motivation of the development team, the ability to set appropriate work units, the appropriateness of work rules, and the improvement of code maintainability should be considered as they are correlated with improved user satisfaction. In contrast, changes in the release frequency and workload are not correlated

    SL1 revisited: functional analysis of the structure and conformation of HIV-1 genome RNA

    Get PDF
    Additional file 1: Figure S1. Native northern blots of HIV-1 genome RNA in virion. Figure S2. The schema of the system for estimating HIV-1 recombination efficiency

    Structural Modeling of HIV-1 Env-gp120

    Get PDF
    Variable V1/V2 and V3 loops on human immunodeficiency virus type 1 (HIV-1) envelope-gp120 core play key roles in modulating viral competence to recognize two infection receptors, CD4 and chemokine-receptors. However, molecular bases for the modulation largely remain unclear. To address these issues, we constructed structural models for a full-length gp120 in CD4-free and -bound states. The models showed topologies of gp120 surface loop that agree with those in reported structural data. Molecular dynamics simulation showed that in the unliganded state, V1/V2 loop settled into a thermodynamically stable arrangement near V3 loop for conformational masking of V3 tip, a potent neutralization epitope. In the CD4-bound state, however, V1/V2 loop was rearranged near the bound CD4 to support CD4 binding. In parallel, cell-based adaptation in the absence of anti-viral antibody pressures led to the identification of amino acid substitutions that individually enhance viral entry and growth efficiencies in association with reduced sensitivity to CCR5 antagonist TAK-779. Notably, all these substitutions were positioned on the receptors binding surfaces in V1/V2 or V3 loop. In silico structural studies predicted some physical changes of gp120 by substitutions with alterations in viral replication phenotypes. These data suggest that V1/V2 loop is critical for creating a gp120 structure that masks co-receptor binding site compatible with maintenance of viral infectivity, and for tuning a functional balance of gp120 between immune escape ability and infectivity to optimize HIV-1 replication fitness
    corecore