1,992 research outputs found

    Investigating the topological structure of quenched lattice QCD with overlap fermions by using multi-probing approximation

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    The topological charge density and topological susceptibility are determined by multi-probing approximation using overlap fermions in quenched SU(3) gauge theory. Then we investigate the topological structure of the quenched QCD vacuum, and compare it with results from the all-scale topological density, the results are consistent. Random permuted topological charge density is used to check whether these structures represent underlying ordered properties. Pseudoscalar glueball mass is extracted from the two-point correlation function of the topological charge density. We study 33 ensembles of different lattice spacing aa with the same lattice volume 163×3216^{3}\times32, the results are compatible with the results of all-scale topological charge density, and the topological structures revealed by multi-probing are much closer to all-scale topological charge density than that by eigenmode expansion.Comment: 12 pages,34 figure

    Time and spatial distribution of multidrug-resistant tuberculosis among Chinese people, 1981–2006: a systematic review

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    SummaryObjectivesWe aimed to investigate trends in the prevalence of multidrug-resistant tuberculosis (MDR-TB) among Chinese people from first report to 2006, and to detect the high prevalence regions in order to guide control efforts.Materials and methodsThe CBM, VIP, CNKI, and MEDLINE databases were searched through both keywords and subject headings. The literature was screened, and two investigators assessed the quality and extracted the data. Trends in MDR-TB prevalence in three groups – primary, acquired, and combined MDR-TB – were examined separately, using the Cochran–Armitage trend test. Differences were tested with the Kruskal–Wallis test. High prevalence provinces were explored through comparison of the 95% confidence interval (95% CI) with the national average level.ResultsOverall 169 studies were included, with 165 in Chinese and four in English. One hundred and sixteen studies concerned primary MDR-TB, 103 acquired MDR-TB, and 130 combined MDR-TB, with total positive Mycobacterium tuberculosis (MTB) isolates of 110 076, 25 187, and 150 233, respectively. The prevalences of MDR-TB in the three groups in 2005 were 2.64-, 6.20-, and 3.84-times that of 1985, respectively, all showing an upward trend (p<0.05). The prevalences among the three groups were significantly different (p<0.05), with acquired drug resistance (27.5%, 95% CI 26.9–28.1%) much higher than primary drug resistance (4.3%, 95% CI 4.2–4.4%), and combined resistance (9.9%, 95% CI 9.8–10.1%) in between. The top three prevalence regions for primary, acquired, and combined MDR-TB were distributed in the zone from the northeast to the southwest of China, with Hebei, Tibet, and Shanxi having an extremely high prevalence.ConclusionsThe prevalence of MDR-TB among the Chinese people has shown an upward trend since 1985. It is necessary to continue to monitor this trend in China. Special attention should be paid to provinces distributed in the zone from the northeast to the southwest of China for MDR-TB surveillance, research, and control

    Numerical and Experimental Research on Cold Compression Deformation Method for Reducing Quenching Residual Stress of 7A85 Aluminum Alloy Thick Block Forging

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    In aeronautical machining industry, the most difficult problem to deal with is the distortion of aviation integral component, one main cause of which is the existence of quenching residual stress of forgings, especially for large-sized ones. Therefore, it is important to study the methods that can reduce the quenching residual stress. In this work, the distribution of quenching residual stress of 7A85 aluminum alloy thick block forging, as well as the effect of cold compression deformation method on reducing quenching residual stress, has been investigated by simulation. The results show that, in length direction of 7A85 aluminum alloy thick block with a large size of 260 (H) × 1150 (W) × 5300 (L) mm, quenching residual stress can be significantly reduced by about 2.5% cold compression deformation along the direction of highness, with residual stress in length direction ranging from −65 MPa to 60 MPa, compared with its counterpart after quenching from −170 MPa to 140 MPa. Then a cold compression experiment was carried out, in which the forging residual stress on the surface was measured by X-ray diffraction device. The experimental results indicate that the optimal compression deformation value is 1%-2%, reducing 70% residual stress for 7A85 aluminum alloy specimens in size of 100 (L) × 60 (W) × 40 (H) mm

    NADPH Oxidase 1 and Its Derived Reactive Oxygen Species Mediated Tissue Injury and Repair

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    Reactive oxygen species are mostly viewed to cause oxidative damage to various cells and induce organ dysfunction after ischemia-reperfusion injury. However, they are also considered as crucial molecules for cellular signal transduction in biology. NADPH oxidase, whose only function is reactive oxygen species production, has been extensively investigated in many cell types especially phagocytes. The deficiency of NADPH oxidase extends the process of inflammation and delays tissue repair, which causes chronic granulomatous disease in patients. NADPH oxidase 1, one member of the NADPH oxidase family, is not only constitutively expressed in a variety of tissues, but also induced to increase expression in both mRNA and protein levels under many circumstances. NADPH oxidase 1 and its derived reactive oxygen species are suggested to be able to regulate inflammation reaction, cell proliferation and migration, and extracellular matrix synthesis, which contribute to the processes of tissue injury and repair

    Effects of matrine on collagen proliferation and TNF-α, TGF-β1 and CTGF in atrial tissues of dogs with persistent atrial fibrillation

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    目的 探讨苦参碱对犬心房颤动(房颤)心房肌组织中胶原合成以及肿瘤坏死因子(tumor necrosis factor alpha,TNF-α)、转化生长因子(transforming growth factor-β1,TGF-β1)和结缔组织生长因子(connective Tissue Growth Factor,CTGF)表达变化的影响。方法 健康比格犬10只采用快速右心室起搏造房颤模型,随机分成房颤组和房颤+苦参碱组各5只。采用天狼星红染色,计算胶原容积分数(collagen volume fraction,CVF)以测定纤维化程度;采用免疫组织化学法检测右心房TNF-α、TGF-β1和CTGF的蛋白表达情况;用逆转录-聚合酶链反应(RT-PCR)技术检测TNF-α、TGF-β1和CTGF的mRNA水平表达情况。结果 与房颤组相比,房颤+苦参碱组纤维化程度降低,CVF明显下降(P<0.05),TNF-α、TGF-β1和CTGF蛋白表达水平下降,且TNF-α和TGF-β1的mRNA表达水平显著下降(P<0.05,P<0.01)。结论 苦参碱可能通过抑制TNF-α、TGF-β1和CTGF的表达,抑制房颤心房肌胶原合成,改善心房组织纤维化程度。Objective:To study the effects of matrine (mat) on collagen synthesis and expression of tumor necrosis factoralpha (TNF-α), and transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) in atrial tissues of dogs with persistent atrial fibrillation (AF). Methods : Ten healthy beagle dogs were randomly divided into two groups: AF group (n=5) and AF/Mat group (n=5), using right ventricular pacing to establish AF model. The collagen volume fraction (CVF) in atrial tissue were detected by sirius red staining to determine the level of fabrication. The level of TNF-α, TGF-β1 and CTGF were detected by immunohisto-chemistry. The mRNA expression level of TNF-α, TGF-β1 and CTGF were detected by reverse transcription-polymerase chain reaction (RT-PCR). Results:  Compared with the AF group, the fabriation level of AF/Mat was decreased obviously (P&lt;0.05), the expression levels of TNF-α, TGF-β1 and CTGF were decreased, and the mRNA expression level were decreased significantly in atrial tissues (P&lt;0.05 and P&lt;0.01). Conclusion: Matrine may inhibits fabrosis in atrial tissues through inhibition collagen proliferation and expression of TNF-α, TGF-β1 and CTGF

    Prognostic Implications of Epidermal Growth Factor Receptor and KRAS Gene Mutations and Epidermal Growth Factor Receptor Gene Copy Numbers in Patients with Surgically Resectable Non-small Cell Lung Cancer in Taiwan

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    IntroductionThe prognostic role of epidermal growth factor receptor (EGFR) mutations in patients with surgically resectable non-small cell lung cancer (NSCLC) without EGFR tyrosine kinase inhibitor treatment has not been well established, because the reports are still few.Materials and MethodsWe analyzed the survival data of 164 patients with surgically resectable (stages I to IIIA) NSCLC of two year groups (1996–1998 and 2002–2004), and compared with EGFR mutations, KRAS mutations, and EGFR gene copy numbers.ResultsComparing the survival of wild-type patients and patients having L858R mutations or exon 19 deletion, the median survival was much longer for patient with EGFR mutations (54.7 months) than wild type (34.9 months). The difference was not statistically significant by univariate analysis (p = 0.1981) but had borderline significance by multivariate analyses (p = 0.0506). In addition, the 3-year survival rates of patients with EGFR mutations were also significantly higher than wild type (p = 0.0232). After exclusion of 18 patients treated by EGFR-tyrosine kinase inhibitor for tumor recurrence, the trends were still the same. Patients with KRAS mutations had shorter median survival (21 months) than wild type (44.4 months). Patients with EGFR polysomy (≧copies) also had longer median survival (56.2 months) than wild type (53.4 months). But the survival differences of these two genetic markers were all not significant statistically.ConclusionIt is intriguing that patients with NSCLC with EGFR mutations had better survival than wild type. Such a tumor biology may confound the survival data in a study without the stratification by EGFR mutation

    Quantitative pinch stimulator for exploring evoked nociceptive responses: A pilot study

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    <p>Abstract</p> <p>Background</p> <p>A mechanical noxious stimulator is useful for studies of pain, both for clinic and basic research. We propose to use a pinch stimulator that can not only generate a quantitative, reproducible noxious pinch but also simultaneously provide a synchronous external trigger signal, which is essential for acquisition of evoked potentials.</p> <p>Methods</p> <p>For ethical considerations, audible and visual aids were incorporated so that pinch force could be regulated within a predetermined level. Reproducibility of the nociceptive responses evoked by this device was validated. The device was constructed with a simple circuit, and the element build-in was delicately selected for the minimum required to produce evoked potentials.</p> <p>Results</p> <p>The magnitude of the force output is linearly proportional to the volts produced by the device (i.e., during the pinch). Increases in force correspond to increases in the number of action potentials induced.</p> <p>Conclusions</p> <p>This device may be useful for studying the mechanisms of nociceptive signal processing in the brain through application of reproducible, noxious pinch stimuli.</p
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