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Search Results: 1 - 10 of 60220 matches for " Wei Xi "
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BSMAP: whole genome bisulfite sequence MAPping program
Yuanxin Xi, Wei Li
BMC Bioinformatics , 2009, DOI: 10.1186/1471-2105-10-232
Abstract: We developed an efficient bisulfite reads mapping algorithm BSMAP to address the above issues. BSMAP combines genome hashing and bitwise masking to achieve fast and accurate bisulfite mapping. Compared with existing bisulfite mapping approaches, BSMAP is faster, more sensitive and more flexible.BSMAP is the first general-purpose bisulfite mapping software. It is able to map high-throughput bisulfite reads at whole genome level with feasible memory and CPU usage. It is freely available under GPL v3 license at http://code.google.com/p/bsmap/ webcite.Cytosine (C) DNA methylation plays a crucial role in various biological processes such as gene expression, chromatin accessibility, and imprinting, as well as in many diseases including cancer. Over the decades, bisulfite sequencing [1] has remained the gold standard for DNA methylation analysis. Bisulfite treatment of DNA followed by PCR amplification leads to a chemical conversion of unmethylated Cs to Ts without affecting As, Gs, Ts or methylated Cs. This C to T conversion results in non-complementarity in the two strands of DNA (Figure 1). Following strand-specific and locus-specific PCR amplification, direct- or pyro-sequencing is used to determine the methylation ratio of any given C locus as the proportion of remaining Cs in all the sequencing reads. This PCR-based procedure is very labor intensive and time-consuming, and therefore inappropriate for high throughput studies.Tremendous progress has been achieved in the past two years in the development of massively parallel sequencing such as Illumina/Solexa and Applied Biosystems/SOLiD. Tens of millions of short tags (36–75 bases) can now be simultaneously sequenced at less than 1% of the cost of traditional Sanger methods. Without the locus-specific PCR step, bisulfite treatment coupled with next-generation shotgun sequencing (BS-seq) [2-4] has become a powerful technique with the potential to quantitatively detect the methylation pattern of every C in the genome. N
Derived equivalences for $Φ$-Auslander-Yoneda algebras
Wei Hu,Changchang Xi
Mathematics , 2009,
Abstract: In this paper, we introduce $\Phi$-Auslander-Yoneda algebras in a triangulated category with $\Phi$ a parameter set in $\mathbb N$, and provide a method to construct new derived equivalences between these $\Phi$-Auslander-Yoneda algebras (not necessarily Artin algebras), or their quotient algebras, from a given almost $\nu$-stable derived equivalence. As consequences of our method, we have: (1) Suppose that $A$ and $B$ are representation-finite, self-injective Artin algebras with $_AX$ and $_BY$ additive generators for $A$ and $B$, respectively. If $A$ and $B$ are derived-equivalent, then the $\Phi$-Auslander-Yoneda algebras of $X$ and $Y$ are derived-equivalent for every admissible set $\Phi$. In particular, the Auslander algebras of $A$ and $B$ are both derived-equivalent and stably equivalent. (2) For a self-injective Artin algeba $A$ and an $A$-module $X$, the $\Phi$-Auslander-Yoneda algebras of $A\oplus X$ and $A\oplus \Omega_A(X)$ are derived-equivalent for every admissible set $\Phi$, where $\Omega$ is the Heller loop operator. Motivated by these derived equivalences between $\Phi$-Auslander-Yoneda algebras, we consider constructions of derived equivalences for quotient algebras, and show, among others, that a derived equivalence between two basic self-injective algebras may transfer to a derived equivalence between their quotient algebras obtained by factorizing out socles.
Compactness Criteria for the Resolvent of Fokker-Planck operator
Wei-Xi Li
Mathematics , 2015,
Abstract: In this paper we study the spectral property of a Fokker-Planck operator with potential. By virtue of a multiplier method inspired by Nicolas Lerner, we obtain new compactness criteria for its resolvent, involving the control of the positive eigenvalues of the Hessian matrix of the potential.
Derived equivalences and stable equivalences of Morita type, I
Wei Hu,Changchang Xi
Mathematics , 2008,
Abstract: For self-injective algebras, Rickard proved that each derived equivalence induces a stable equivalence of Morita type. For general algebras, it is unknown when a derived equivalence implies a stable equivalence of Morita type. In this paper, we first show that each derived equivalence $F$ between the derived categories of Artin algebras $A$ and $B$ arises naturally a functor $\bar{F}$ between their stable module categories, which can be used to compare certain homological dimensions of $A$ with that of $B$; and then we give a sufficient condition for the functor $\bar{F}$ to be an equivalence. Moreover, if we work with finite-dimensional algebras over a field, then the sufficient condition guarantees the existence of a stable equivalence of Morita type. In this way, we extend the classic result of Rickard. Furthermore, we provide several inductive methods for constructing those derived equivalences that induce stable equivalences of Morita type. It turns out that we may produce a lot of (usually not self-injective) finite-dimensional algebras which are both derived-equivalent and stably equivalent of Morita type, thus they share many common invariants.
Almost $\cal D$-split sequences and derived equivalences
Wei Hu,Changchang Xi
Mathematics , 2008,
Abstract: In this paper, we introduce almost $\cal D$-split sequences and establish an elementary but somewhat surprising connection between derived equivalences and Auslander-Reiten sequences via BB-tilting modules. In particular, we obtain derived equivalences from Auslander-Reiten sequences (or $n$-almost split sequences), and Auslander-Reiten triangles.
Global Hypoellipticity and Compactness of Resolvent for Fokker-Planck Operator
Wei-Xi Li
Mathematics , 2009,
Abstract: In this paper we study the Fokker-Planck operator with potential V(x), and analyze some kind of conditions imposed on the potential to ensure the validity of global hypoelliptic estimates. As a consequence, we obtain the compactness of resolvent of the Fokker-Planck operator if either the Witten Laplacian on 0-forms has a compact resolvent or some additional assumption on the behavior of the potential at infinity is fulfilled. This work improves the previous results of H\'erau-Nier and Helffer-Nier, by obtaining a better global hypoelliptic estimate under weaker assumptions on the potential.
Global hypoelliptic estimates for a linear model of non-cutoff Boltzmann equation
Wei-Xi Li
Mathematics , 2011,
Abstract: In this paper we study a linear model of spatially inhomogeneous Boltzmann equation without angular cutoff. Using the multiplier method introduced by F. H\'{e}rau and K. Pravda-Starov (2011), we establish the optimal global hypoelliptic estimate with weights for the linear model operator
Derived equivalences and stable equivalences of Morita type, II
Wei Hu,Changchang Xi
Mathematics , 2014,
Abstract: Motivated by understanding the Brou\'e's abelian defect group conjecture from algebraic point of view, we consider the question of how to lift a stable equivalence of Morita type between arbitrary finite dimensional algebras to a derived equivalence. In this paper, we present a machinery to solve this question for a class of stable equivalences of Morita type. In particular, we show that every stable equivalence of Morita type between Frobenius-finite algebras over an algebraically closed field can be lifted to a derived equivalence. %Thus Frobenius-finite algebras share many common %invariants of both derived equivalences and stable equivalences. Especially, Auslander-Reiten conjecrure is true for stable equivalences of Morita type between Frobenius-finite algebras without semisimple direct summands. Examples of such a class of algebras are abundant, including Auslander algebras, cluster-tilted algebras and certain Frobenius extensions. As a byproduct of our methods, we further show that, for a Nakayama-stable idempotent element $e$ in an algebra $A$ over an arbitrary field, each tilting complex over $eAe$ can be extended to a tilting complex over $A$ that induces an almost $\nu$-stable derived equivalence studied in the first paper of this series. Moreover, we demonstrate that our techniques are applicable to verify the Brou\'{e}'s abelian defect group conjecture for several cases mentioned by Okuyama.
Down Regulation of Survivin Gene and Up Regulation of p53 Gene expression by siRNA Induces Apoptosis in human Hepatocellular Carcinoma cell Line HepG2  [PDF]
Yun-Hua Lu, Cong Tang, Wei Wang, Tao Xi
Journal of Biomedical Science and Engineering (JBiSE) , 2009, DOI: 10.4236/jbise.2009.21010
Abstract: Survivin gene may be a good target for cancer gene therapy because it is over expressed in a variety of human tumors including human hepatocellular carcinoma but not in differen- tiated adult tissues. To explore the effects of the siRNA of survivin gene inducing apoptosis in human hepatocellular cancer cells, three siRNAs cpusiRNA1, cpusiRNA2 and cpusiRNA3 were designed and transferred into human hepatocellular carcinoma cell line HepG2 (HepG2) by lipofection. MTT test showed that the growth of HepG2 decreased when it was transfected with 25nM, 50nM, 100nM, 150nM, 200nM, 400nM siRNA respectively after 48 hours. And the change of mRNA and protein of survivin gene and p53 gene had been detected by RT-PCR and Western blot. Cells presented an increase in apoptosis index was assayed by flow cytometry. Small interfering RNA can exert a knockdown of survivin gene expression and up regulation of p53 gene to induce apoptosis and to inhibit the growth of HepG2.
Design and Key Technology of Gardening Information Management System Based on Data Center  [PDF]
Xi-Guang Wang, Wei-Hua Lin, Wen Zeng
Journal of Geographic Information System (JGIS) , 2010, DOI: 10.4236/jgis.2010.22015
Abstract: To provide scientific management basis for the garden planning, project construction, maintenance, social service, this paper prompted that the urban gardening administration sectors need to construct gardening information management system. On the basis of fully requirements analysis of gardening sectors, this paper discussed the key technology for system construction. It also proposed to flexibly and smartly build up the system by using the secondary development design environment and running environment based on data center integration development platform. This system greatly helps the daily management and plays very important role in improving urban ecological environment and investment environment.
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