74 research outputs found

    Exact convergence rates in central limit theorems for a branching random walk with a random environment in time

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    Chen [Ann. Appl. Probab. {\bf 11} (2001), 1242--1262] derived exact convergence rates in a central limit theorem and a local limit theorem for a supercritical branching Wiener process.We extend Chen's results to a branching random walk under weaker moment conditions. For the branching Wiener process, our results sharpen Chen's by relaxing the second moment condition used by Chen to a moment condition of the form \E X (\ln^+X )^{1+\lambda}< \infty. In the rate functions that we find for a branching random walk, we figure out some new terms which didn't appear in Chen's work.The results are established in the more general framework, i.e. for a branching random walk with a random environment in time.The lack of the second moment condition for the offspring distribution and the fact that the exponential moment does not exist necessarily for the displacements make the proof delicate; the difficulty is overcome by a careful analysis of martingale convergence using a truncating argument. The analysis is significantly more awkward due to the appearance of the random environment.Comment: Corrected version of https://hal.archives-ouvertes.fr/hal-01095105. arXiv admin note: text overlap with arXiv:1504.01181 by other author

    Second and third orders asymptotic expansions for the distribution of particles in a branching random walk with a random environment in time

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    Consider a branching random walk in which the offspring distribution and the moving law both depend on an independent and identically distributed random environment indexed by the time.For the normalised counting measure of the number of particles of generation nn in a given region, we give the second and third orders asymptotic expansions of the central limit theorem under rather weak assumptions on the moments of the underlying branching and moving laws. The obtained results and the developed approaches shed light on higher order expansions. In the proofs, the Edgeworth expansion of central limit theorems for sums of independent random variables, truncating arguments and martingale approximation play key roles. In particular, we introduce a new martingale, show its rate of convergence, as well as the rates of convergence of some known martingales, which are of independent interest.Comment: Accepted by Bernoull

    FIELD TEST ON THE COOPERATION OF NSM STRENGTHENING AND EXTERNAL TENDON RETROFITTING TECHNIQUE

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    In this paper, post-tension and steel plate near-surface mounted (NSM) strengthening systems are proposed to strengthen deteriorated and cracked large box girder rigid frame bridge without altering appearance and dimension of the bridge. The reinforcement method mainly improves the bearing capacity through external prestressed tendons, and bonding steel plate can enhance the shear resistance of the bridge. The main purpose is to study the structural mechanical properties before and after the reinforcement of rigid frame bridges. Take a 540m rigid frame box girder bridge as an example. The static load test of the bridge before and after reinforcement is carried out. The deflection and strain of the middle cross section of the span are measured in the static test. A finite element analysis model was also developed and verified static loading test data. The results show that structural bearing capacity and performance of the bridge were enhanced with the post-tension and NSM strengthening systems cooperatively

    PO-078 Effects of aerobic and resistance training on cardiac diastolic dysfunction in type 2 diabetic rats

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    Objective To compare the effects of two types of physical training on cardiac diastolic dysfunction in type 2 diabetes mellitus and investigate the role of passive tension regulators—titin and collagen. Methods Sprague-Dawley (SD) male rats were divided into two groups: control and diabetes. Each group was subdivided into three subgroups: sedentary rats, rats submitted to aerobic trained and rats submitted to resistance training. Diabetic rats were induced by high-fat diet combined with low-dose injections of streptozocin (STZ). Aerobic trained rats ran on a treadmill at 21m/min for 60 min per day, while resistance trained rats climbed a ladder with incremental loads. The train period lasted for 8 weeks. Results All diabetic rats had increased fasting blood glucose (FBG) and left ventricular end diastolic pressure (LVEDP), a lower down stroke of the pressure curve (dp/dt min), longer exponential time constants of relaxation (Tau) in relation to control rats, while the protein expression of titin was decreased significantly, and the expression of collagen I, TGFβ1 were increased slightly, the ratio of type I and III collagen was raised in diabetic rats. Both types of training promoted a decrease in FBG and HOMA-IR in diabetic rats. Aerobic exercise trained diabetic rats had significant higher –dp/dtmin, and shorter Tau, but -dp/dtmin and Tau in resistance exercise trained diabetic rats had no significant been improved, even more aggravation. Moreover, aerobic training increased the protein expression of titin and HSP27, and the amount of co-localization of titin and HSP27 elevated, the protein expression of collagen I, TGFβ1 were decreased, and the ratio of type I and type III got close to normal. Resistance training further decreased the expression of titin, collagen I, and TGFβ1, collagen volume fraction (CVF) was increased significantly, and the ratio of type I and III collagen was disturbed, but the co-localization of titin and HSP27 elevated slightly. Conclusions Aerobic training ameliorates cardiac diastolic dysfunction in diabetes and this improvement may be related to increase titin repaired by HSP27, while resistance training aggravates the cardiac diastolic dysfunction in early diabetes mellitus and it could be caused by worsening myocardial interstitial fibrosis

    TOC interpretation of lithofacies-based categorical regression model: A case study of the Yanchang formation shale in the Ordos basin, NW China

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    In this paper, taking the shale of Chang 7-Chang 9 oil formation in Yanchang Formation in the southeastern Ordos Basin as an example, through the study of shale heterogeneity characteristics, starting from the preprocessing of supervision data set, a logging interpretation method of total organic carbon content (TOC) on the lithofacies-based Categorical regression model (LBCRM) is proposed. It is show that: 1) Based on core observation, and Differences of sedimentation and structure, five lithofacies developed in the Yanchang Formation: shale shale facies, siltstone/ultrafine sandstone facies, tuff facies, argillaceous shale facies with silty lamina and argillaceous shale facies with tuff lamina. 2) The strong heterogeneity of shale makes it difficult to accurately explain the TOC distribution of shale intervals in the application of model-based interpretation methods. The LBCRM interpretation method based on the understanding of shale heterogeneity can effectively reduce the influence of formation factors other than TOC on the prediction accuracy by studying the characteristics of shale heterogeneity and constructing a TOC interpretation model for each lithofacies category. At the same time, the degree of unbalanced distribution of data is reduced, so that the data mining algorithm achieves better prediction effect. 3) The interpretability of lithofacies logging ensures the wellsite application based on the classification and regression model of lithofacies. Compared with the traditional homogeneous regression model, the prediction performance has been greatly improved, TOC segment prediction is more accurate. 4) The LBCRM method based on shale heterogeneity can better understand the reasons for the deviation of the traditional model-based interpretation method. After being combined with the latter, it can make logging data provide more useful information

    Genetic Heterogeneity of Oesophageal Cancer in High-Incidence Areas of Southern and Northern China

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    BACKGROUND AND OBJECTIVE: Oesophageal cancer is one of the most common and deadliest cancers worldwide. Our previous population-based study reported a high prevalence of oesophageal cancer in Chaoshan, Guangdong Province, China. Ancestors of the Chaoshan population migrated from the Taihang Mountain region of north-central China, which is another high-incidence area for oesophageal cancer. The purpose of the present study was to obtain evidence of inherited susceptibility to oesophageal cancer in the Chaoshan population, with reference to the Taihang Mountain population, with the eventual goal of molecular identification of the disease genes. METHODS: We conducted familial correlation, commingling, and complex segregation analyses of 224 families from the Chaoshan population and 403 families from the Taihang population using the FPMM program of S.A.G.E. version 5.3.0. A second analysis focused on specific families having large numbers of affected individuals or early onset of the disease. RESULTS: For the general population, moderate sib-sib correlation was noticed for esophageal cancer. Additionally, brother-brother correlation was even higher. Commingling analyses indicated that a three-component distribution model best accounts for the variation in age of onset of oesophageal cancer, and that a multifactorial model provides the best fit to the general population data. An autosomal dominant mode and a dominant or recessive major gene with polygenic inheritance were found to be the best models of inherited susceptibility to oesophageal cancer in some large families. CONCLUSIONS: The current results provide evidence for inherited susceptibility to oesophageal cancer in certain high-risk groups in China, and support efforts to identify the susceptibility genes

    Identification of Piwil2-Like (PL2L) Proteins that Promote Tumorigenesis

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    PIWIL2, a member of PIWI/AGO gene family, is expressed in the germline stem cells (GSCs) of testis for gametogenesis but not in adult somatic and stem cells. It has been implicated to play an important role in tumor development. We have previously reported that precancerous stem cells (pCSCs) constitutively express Piwil2 transcripts to promote their proliferation. Here we show that these transcripts de facto represent Piwil2-like (PL2L) proteins. We have identified several PL2L proteins including PL2L80, PL2L60, PL2L50 and PL2L40, using combined methods of Gene-Exon-Mapping Reverse Transcription Polymerase Chain Reaction (GEM RT-PCR), bioinformatics and a group of novel monoclonal antibodies. Among them, PL2L60 rather than Piwil2 and other PL2L proteins is predominantly expressed in various types of human and mouse tumor cells. It promotes tumor cell survival and proliferation in vitro through up-regulation of Stat3 and Bcl2 gene expressions, the cell cycle entry from G0/1 into S-phase, and the nuclear expression of NF-ÎşB, which contribute to the tumorigenicity of tumor cells in vivo. Consistently, PL2L proteins rather than Piwil2 are predominantly expressed in the cytoplasm or cytoplasm and nucleus of euchromatin-enriched tumor cells in human primary and metastatic cancers, such as breast and cervical cancers. Moreover, nuclear PL2L proteins are always co-expressed with nuclear NF-ÎşB. These results reveal that PL2L60 can coordinate with NF-ÎşB to promote tumorigenesis and might mediate a common pathway for tumor development without tissue restriction. The identification of PL2L proteins provides a novel insight into the mechanisms of cancer development as well as a novel bridge linking cancer diagnostics and anticancer drug development

    Lowe Syndrome Protein OCRL1 Supports Maturation of Polarized Epithelial Cells

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    Mutations in the inositol polyphosphate 5-phosphatase OCRL1 cause Lowe Syndrome, leading to cataracts, mental retardation and renal failure. We noted that cell types affected in Lowe Syndrome are highly polarized, and therefore we studied OCRL1 in epithelial cells as they mature from isolated individual cells into polarized sheets and cysts with extensive communication between neighbouring cells. We show that a proportion of OCRL1 targets intercellular junctions at the early stages of their formation, co-localizing both with adherens junctional components and with tight junctional components. Correlating with this distribution, OCRL1 forms complexes with junctional components α-catenin and zonula occludens (ZO)-1/2/3. Depletion of OCRL1 in epithelial cells growing as a sheet inhibits maturation; cells remain flat, fail to polarize apical markers and also show reduced proliferation. The effect on shape is reverted by re-expressed OCRL1 and requires the 5′-phosphatase domain, indicating that down-regulation of 5-phosphorylated inositides is necessary for epithelial development. The effect of OCRL1 in epithelial maturation is seen more strongly in 3-dimensional cultures, where epithelial cells lacking OCRL1 not only fail to form a central lumen, but also do not have the correct intracellular distribution of ZO-1, suggesting that OCRL1 functions early in the maturation of intercellular junctions when cells grow as cysts. A role of OCRL1 in junctions of polarized cells may explain the pattern of organs affected in Lowe Syndrome

    First and second order expansions in the central limit theorem for a branching random walk

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    International audienceWe give the first-and second-order asymptotic expansions for the central limit theorem about the distribution of particles in a branching random walk on the real line. In particular, our first-order expansion reveals the exact convergence rate in the central limit theorem; it extends and improves a known result for the branching Wiener process
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