7,020 research outputs found

    Mechanism for the Increased Permeability in Endothelial Monolayers Induced by Elastase

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    The aim of this study was to investigate the mechanism for the increase in endothelial permeability induced by human neutrophil elastase (HNE). Pretreatment of bovine pulmonary artery endothelial cells (BPAEC) with HNE(0-30 Όg/ml) for 1 h produced a concentration dependent increase in 125I-albumin clearance. The effect was reversible and was not due to cytolysis. Pretreatment of BPAEC with sodium tungstate, which depletes xanthine oxidase, or with oxypurinol, did not prevent HNE induced increased permeability. Heparin, which neutralizes the cationic charge of HNE, also had no protective effect. Pretreatment with heat inactivated HNE, which still had positive charge sites, did not result in increased endothelial permeability. Also, ONO-5046, a novel specific inhibitor of HNE, did prevent increased permeability. These results suggest that elastase increases endothelial permeability mainly through its proteolytic effects

    Ion-induced nucleation in polar one-component fluids

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    We present a Ginzburg-Landau theory of ion-induced nucleation in a gas phase of polar one-component fluids, where a liquid droplet grows with an ion at its center. By calculating the density profile around an ion, we show that the solvation free energy is larger in gas than in liquid at the same temperature on the coexistence curve. This difference much reduces the nucleation barrier in a metastable gas.Comment: 9 pagers, 9 figures, to be published in J. Chem. Phy

    Integrated Land Use-Transport Model System with Dynamic Time-Dependent Activity-Travel Microsimulation

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    The development of integrated land use-transport model systems has long been of interest because of the complex interrelationships between land use, transport demand, and network supply. This paper describes the design and prototype implementation of an integrated model system that involves the microsimulation of location choices in the land use domain, activity-travel choices in the travel demand domain, and individual vehicles on networks in the network supply modeling domain. Although many previous applications of integrated transport demand-supply models have relied on a sequential coupling of the models, the system presented in this paper involves a dynamic integration of the activity-travel demand model and the dynamic traffic assignment and simulation model with appropriate feedback to the land use model system. The system has been fully implemented, and initial results of model system runs in a case study test application suggest that the proposed model design provides a robust behavioral framework for simulation of human activity-travel behavior in space, time, and networks. The paper provides a detailed description of the design, together with results from initial test runs

    Numerical Study on Split Coil-shaped HTS Bulks to Improve the Field Homogeneity for Compact NMR Relaxometry Magnets

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    AbstractWe have been developing a new compact NMR magnet using stacked HTS bulks. In this pa er, in order to improve the trapped magnetic field homogeneity and to obtain the enlarged sample space of HTS bulk magnet for compact NMR relaxometry, the HTS bulk magnet with 10mm gap length in the center region of HTS bulk magnet (we call it “split coil-shaped THS bulks”) were proposed and studied as the functions of size and shape of HTS bulk using 3D FEM based electromagnetic analysis. The improved field homogeneity was obtained using notch coil shaped HTS bulk configuration and the field compensation by attached the coil instated of the bulks

    Understanding factors contributing to outbreaks of diphtheria and implications for vaccination policy in Vietnam

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    Background: Diphtheria is a severe, acute infectious disease caused by toxin-producing Corynebacterium species, mainly C. diphtheriae. The diphtheria toxoid vaccine successfully reduced global diphtheria incidence. However, diphtheria remains endemic in many countries. Currently, the World Health Organization recommends three primary doses during infancy and three booster doses until the adolescent period; however, many low- and middle-income countries have not introduced all booster doses. Vietnam experienced several outbreaks of diphtheria in the last decade. This thesis aims to elucidate the mechanism of diphtheria outbreaks and appropriate vaccination strategies in Vietnam. Methods: This thesis consists of five components: first, the diphtheria outbreak in Vietnam is described with the available data (Chapter 3); second, a systematic review was conducted with age-specific seroprevalence data from 15 countries to estimate the optimal booster dose interval (Chapter 4); third, a cross-sectional and cohort study was conducted in a well-vaccinated community in Vietnam with no reported cases to assess population immunity and the waning of vaccine-derived immunity (Chapter 5); fourth, another cross-sectional carriage prevalence and seroprevalence survey was conducted in an epidemic-prone area (Chapter 6); and finally, a validation study for enzyme-linked immunosorbent assay (ELISA) was conducted via parallel comparison of ELISA and neutralising test measurements (Chapter 7). Results: In Chapter 3, we found that 73% of diphtheria cases reported in Central Vietnam between 2015 and 2018 were in school-age children. While this finding indicated that there is an immunity gap in school aged children, Chapter 5 confirmed the low seroprevalence in the age group of 6-15 years (7%). In Chapter 3, we identified two fatal cases (7 and 13 years old) who had received three or more doses of the diphtheria-tetanus-pertussis (DTP) vaccine, indicating that vaccine-derived immunity waned or vaccine was not effective. The findings in Chapter 5 suggested that the duration of protection of vaccine-derived immunity was 4.3 years after four doses of DTP, which was much shorter than the commonly perceive 10 years. In contrast, the systematic review in Chapter 4 suggested that the interval between the fourth and fifth doses could be up to 10.3 years. In Chapter 3, strains of the same genetic type were shared by all epidemiologically linked cases; however, it was often impossible to track the transmission chains. The findings indicated that local transmission of C. diphtheriae was attributed to multiple strains with asymptomatic carriers. In Chapter 6, we identified that 1.4% of the population were asymptomatic carriers; the highest carriage prevalence was observed in individuals aged 1–5 years (4.5%), which was much higher than the recently reported carriage prevalence in Europe. Furthermore, 67% of carriers harboured a non-toxigenic strain. Seroprevalence identified in epidemic and non-epidemic settings varied. Seroprevalence among 1–5-year-old in the epidemic-prone area was low due to the limited vaccination history and low seroconversion rate, probably derived from the children’s poor nutrition status. These children (asymptomatic carriers) might maintain transmission of C. diphtheriae in their communities. When the bacteria reaches susceptible hosts, likely school-age children, they are detected as symptomatic cases. This is likely the mechanism of the current diphtheria outbreak in Vietnam. Chapter 7 confirmed that the ELISA method used for the study showed appropriate protection levels in the population when a cut-off value of 0.1 IU/ml was used. Conclusions: The most susceptible age group in Vietnam was school-age children due to the waning of vaccine-derived immunity. In addition, the recent diphtheria epidemic in Vietnam might be attributed to the low vaccine coverage due to limited healthcare access and the low seroconversion rate due to child malnutrition. Based on these findings, it was concluded that improved DTP3 coverage and a school-entry booster dose are essential to control the transmission of C. diphtheriae in Vietnam. In the long term, multiple booster doses will be required to reduce the susceptible population

    Hexaazide octahedral molybdenum cluster complexes: synthesis, properties and the evidence of hydrolysis

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    This article reports the synthesis, crystal structure of new molybdenum hexaazide cluster complex (ⁿBu₄N)₂[{Mo₆I₈}(N₃)₆] (3) and comparison of its photophysical and electrochemical properties to those of earlier reported analogues (ⁿBu₄N)₂[{M₆X₈}(N₃)₆] (X = Cl, Br). Additionally, the dimerisation of 3 as a result of hydrolysis was revealed by mass spectrometry and single crystal X-Ray diffraction. Indeed, the structurally characterised compound (ⁿBu₄N)₄[{Mo₆I₈}(N₃)₅)₂O] represents the first example of oxo-bridged dimer of octahedral molybdenum clusters complexes

    Constraints on the disk geometry of the T Tauri star AA Tau from linear polarimetry

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    We have simultaneously monitored the photometric and polarimetric variations of the Classical T Tauri star AA Tau during the fall of 2002. We combine these data with previously published polarimetric data covering two earlier epochs. The phase coverage is complete, although not contiguous. AA Tau clearly shows cyclic variations coupled with the rotation of the system. The star-disk system produces a repeatable polarisation curve where the polarisation increases with decreasing brightness. The data fit well with the model put forward by Bouvier et al. (1999) where AA Tau is viewed almost edge-on and its disk is actively dumping material onto the central star via magnetospheric accretion. The inner edge of the disk is deformed by its interaction with the tilted magnetosphere, producing eclipses as it rotates and occults the photosphere periodically. From the shape of the polarisation curve in the QU-Plane we confirm that the accretion disk is seen at a large inclination, almost edge-on, and predict that its position angle is PA~90 deg., i.e., that the disk's major axis is oriented in the East-West direction.Comment: Astron. Astrophys., in pres

    Random walks on finite lattice tubes

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    Exact results are obtained for random walks on finite lattice tubes with a single source and absorbing lattice sites at the ends. Explicit formulae are derived for the absorption probabilities at the ends and for the expectations that a random walk will visit a particular lattice site before being absorbed. Results are obtained for lattice tubes of arbitrary size and each of the regular lattice types; square, triangular and honeycomb. The results include an adjustable parameter to model the effects of strain, such as surface curvature, on the surface diffusion. Results for the triangular lattice tubes and the honeycomb lattice tubes model diffusion of adatoms on single walled zig-zag carbon nano-tubes with open ends.Comment: 22 pages, 4 figure

    Mixing among light scalar mesons and L=1 q\bar{q} scalar mesons

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    Following the re-establishment of the \sigma(600) and the \kappa(900), the light scalar mesons a_0(980) and f_0(980) together with the \sigma(600) and the \kappa(900) are considered as the chiral scalar partner of pseudoscalar nonet in SU(3) chiral symmetry, and the high mass scalar mesons a_0(1450), K^*_0(1430), f_0(1370) and f_0(1710) turned out to be considered as the L=1 q\bar{q} scalar mesons. We assume that the high mass of the L=1 q\bar{q} scalar mesons is caused by the mixing with the light scalar mesons. For the structure of the light scalar mesons, we adopted the qq\bar{q}\bar{q} model in order to explain the "scalar meson puzzle". The inter-mixing between the light scalar nonet and the high mass L=1 q\bar{q} nonet and the intra-mixing among each nonet are analyzed by including the glueball into the high mass scalar nonet.Comment: 16 pages, 5 figure

    AKARI Far-Infrared All Sky Survey

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    We demonstrate the capability of AKARI for mapping diffuse far-infrared emission and achieved reliability of all-sky diffuse map. We have conducted an all-sky survey for more than 94 % of the whole sky during cold phase of AKARI observation in 2006 Feb. -- 2007 Aug. The survey in far-infrared waveband covers 50 um -- 180 um with four bands centered at 65 um, 90 um, 140 um, and 160 um and spatial resolution of 3000 -- 4000 (FWHM).This survey has allowed us to make a revolutionary improvement compared to the IRAS survey that was conducted in 1983 in both spatial resolution and sensitivity after more than a quarter of a century. Additionally, it will provide us the first all-sky survey data with high-spatial resolution beyond 100 um. Considering its extreme importance of the AKARI far-infrared diffuse emission map, we are now investigating carefully the quality of the data for possible release of the archival data. Critical subjects in making image of diffuse emission from detected signal are the transient response and long-term stability of the far-infrared detectors. Quantitative evaluation of these characteristics is the key to achieve sensitivity comparable to or better than that for point sources (< 20 -- 95 [MJy/sr]). We describe current activities and progress that are focused on making high quality all-sky survey images of the diffuse far-infrared emission.Comment: To appear in Proc. Workshop "The Space Infrared Telescope for Cosmology & Astrophysics: Revealing the Origins of Planets and Galaxies". Eds. A.M. Heras, B. Swinyard, K. Isaak, and J.R. Goicoeche
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