913 research outputs found

    Radiative Leptonic Decays of BcB_c Meson

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    To the leading order, the radiative leptonic decays Bc→γℓνˉB_c \to \gamma \ell \bar \nu (ℓ=e,μ \ell=e, \mu) are studied carefully. In the study, a non-relativistic constituent quark model and the effective Lagrangian for the heavy flavour decays are used. As a result, the branching ratios turn out to be of the orders of 10−510^{-5} for Bc→γμνˉB_c \to \gamma \mu \bar \nu or for Bc→γeνˉB_c \to \gamma e \bar \nu . Based on this study, we point out the decays being accessible experimentally at the future LHC, and the possibility to determine the decay constant fBcf_{B_c} through the radiative decays.Comment: 9 pages Latex, including 2 figure

    Lymphocyte Adhesion to Psoriatic Dermal Endothelium: Mechanism and Modulation

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    Psoriasis is characterized by the hyperproliferation of keratinocytes in the epidermis and the accumulation of activated CD4+ T lymphocytes in the upper dermis. We have recently rested the hypothesis that the abnormal endothelial proliferation in the dermal papillae of psoriaric lesions may be mechanistically linked to the expression of endothelial ligands capable of promoting lymphocytes binding and extravasation. The results indicated that specialized endothelial cells lining the post-capillary venules of psoriatic lesions are capable of promoting the selective adherence of human CD4+ T cells and its memory subset. In contrast, B cells, CD8+ T cells, and CD45RA+ T cells are deficient in their capacities to bind. The adhesion process is energy and calcium dependent and involves tissue-specific lymphocyte receptors, with LFA-1 molecules playing an accessory role. We concluded that transformation of the dermal endothelium into a lymphocyte-receptive phenotype by defined growth factors or cytokines may represent a positive feedback mechanism promoting lymphocyte migration into the diseased sites

    Data Processing Pipeline for Pointing Observations of Lunar-based Ultraviolet Telescope

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    We describe the data processing pipeline developed to reduce the pointing observation data of Lunar-based Ultraviolet Telescope (LUT), which belongs to the Chang'e-3 mission of the Chinese Lunar Exploration Program. The pointing observation program of LUT is dedicated to monitor variable objects in a near-ultraviolet (245-345 nm) band. LUT works in lunar daytime for sufficient power supply, so some special data processing strategies have been developed for the pipeline. The procedures of the pipeline include stray light removing, astrometry, flat fielding employing superflat technique, source extraction and cosmic rays rejection, aperture and PSF photometry, aperture correction, and catalogues archiving, etc. It has been intensively tested and works smoothly with observation data. The photometric accuracy is typically ~0.02 mag for LUT 10 mag stars (30 s exposure), with errors come from background noises, residuals of stray light removing, and flat fielding related errors. The accuracy degrades to be ~0.2 mag for stars of 13.5 mag which is the 5{\sigma} detection limit of LUT.Comment: 10 pages, 7 figures, 4 tables. Minor changes and some expounding words added. Version accepted for publication in Astrophysics and Space Science (Ap&SS

    Metformin improves the angiogenic functions of endothelial progenitor cells via activating AMPK/eNOS pathway in diabetic mice

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    Additional file 3: Figure S3. BM-EPC functions under the osmotic pressure equal to that of high glucose (HG). Compared with the normal glucose (NG), BM-EPCs treated by mannitol to make equal osmotic pressure with HG showed no significant changes in tube formation and migration.**P < 0.01, vs NG; # P < 0.05 vs HG. Values are mean ± SEM (n = 5 per group)

    Expression of telomerase inhibits hydroxyl radical-induced apoptosis in normal telomerase negative human lung fibroblasts

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    AbstractIn tumor cells telomerase activity is associated with resistance to apoptosis and the introduction of the human telomerase reverse transcriptase (hTERT) subunit into normal human cells is associated with life span extension of the cells. To determine the role of telomerase in regulating apoptosis, telomerase negative human embryo lung fibroblasts were transfected with the hTERT gene. Unlike the control fibroblasts, the telomerase-expressing cells had elongated telomeres and were resistant to apoptosis induced by hydroxyl radicals. The results indicate that expression of telomerase and, thus, the maintenance of telomere length in normal human somatic cells caused resistance to not only cellular senescence but also apoptosis. Moreover, we found that hydroxyl radical-induced apoptosis in telomerase-expressing and control fibroblasts was caspase-3 independent. These findings have revealed a new type of interrelation between telomerase and caspase-3, which may indicate that in this case the expressed telomerase may inhibit apoptosis at a site not related to the caspase-3 cascade

    Numerical Study on the Dynamic Process of Single Plume Flow in Thermal Convection with Polymers

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    A direct numerical simulation of single plume flow in thermal convection with polymers was carried out in a domain with 1:3 as the width to height ratio. The heat transport ability is weakened by adding polymers within the here-investigated governing parameter range. However, it is promoted when the maximum polymer extension L is increased. The distribution of vertical velocity and temperature indicates that the plume in the polymer solution case is speeded up and widens bigger as compared to that in the Newtonian fluid case. Inside the plume, polymer chains tend to release energy at the position where the velocity is decelerated. The ratio of Nusselt numbers (Nu/NuNew) shows the power-law scaling relation with the governing parameter L2/Wi in polymer solution cases, which is only applicable for moderate Wi and small L. The present study can give direct insight into the observation about plumes in turbulent thermal convection experiments. It is therefore useful for the analysis of heat transport in thermal convection with polymers

    The prevalence of autism spectrum disorders in China: A comprehensive meta-analysis

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    There are conflicting prevalence estimates of autism spectrum disorders (ASDs) in mainland China (China thereafter). This study is a comprehensive meta-analysis of the pooled prevalence of ASDs in the general population in China. Study investigators independently conducted a systematic literature search of the following databases: PubMed, EMBASE, PsycINFO, China National Knowledge Infrastructure, Chinese biomedical literature service system, and Wan Fang. Studies reporting prevalence of ASDs and autism in Chinese population were identified and analysed using the Comprehensive Meta-Analysis program with the random effects model. Forty-four studies were included in the meta-analysis comprising 2,337,321 subjects of whom 46.66 % were females. The mean age of subjects ranged from 1.6 to 8 years. Based on diagnostic criteria the pooled prevalence of ASDs was 39.23 per 10,000 (95% CI: 28.44-50.03 per 10,000, I2=89.2%); specifically, the prevalence of autism was 10.18 per 10,000 (95% CI: 8.46-11.89 per 10,000, I2=92.5%). Subgroup analyses revealed significant difference in the prevalence of ASDs between genders (72.77 per 10,000 in males vs. 16.45 per 10,000 in females). In conclusion, the prevalence of ASDs and autism in China was found generally lower than those reported in other countries. Further studies are needed to clarify the variation in prevalence
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