941 research outputs found

    Stochastic Block Mirror Descent Methods for Nonsmooth and Stochastic Optimization

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    In this paper, we present a new stochastic algorithm, namely the stochastic block mirror descent (SBMD) method for solving large-scale nonsmooth and stochastic optimization problems. The basic idea of this algorithm is to incorporate the block-coordinate decomposition and an incremental block averaging scheme into the classic (stochastic) mirror-descent method, in order to significantly reduce the cost per iteration of the latter algorithm. We establish the rate of convergence of the SBMD method along with its associated large-deviation results for solving general nonsmooth and stochastic optimization problems. We also introduce different variants of this method and establish their rate of convergence for solving strongly convex, smooth, and composite optimization problems, as well as certain nonconvex optimization problems. To the best of our knowledge, all these developments related to the SBMD methods are new in the stochastic optimization literature. Moreover, some of our results also seem to be new for block coordinate descent methods for deterministic optimization

    Linearly Convergent First-Order Algorithms for Semi-definite Programming

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    In this paper, we consider two formulations for Linear Matrix Inequalities (LMIs) under Slater type constraint qualification assumption, namely, SDP smooth and non-smooth formulations. We also propose two first-order linearly convergent algorithms for solving these formulations. Moreover, we introduce a bundle-level method which converges linearly uniformly for both smooth and non-smooth problems and does not require any smoothness information. The convergence properties of these algorithms are also discussed. Finally, we consider a special case of LMIs, linear system of inequalities, and show that a linearly convergent algorithm can be obtained under a weaker assumption

    Photofragmentation of carbonyl sulfide (Ocs) following core-shell photoexcitation and photoionization

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    Mass spectroscopy is used to study the formation of cations and anions after photoexcitation and photoionization of OCS in the vicinity of the S 2p, C 1s and O 1s thresholds. Singly charged cations are produced predominantly at the pi* and Rydberg resonances while dications are major products of dissociative channels above the thresholds. At the S 2p threshold, broad Franck-Condon regions observed for Rydberg excited states manifests an apparent change in molecular bond lengths upon the excitation of S 2p electrons to Rydberg orbitals. Neutral dissociation of the pi*3/2, pi*1/2 and 4S 3/2 excited states is found to compete efficiently with electronic relaxation via Auger processes. The observation of SO+ ions at the pi* resonance indicates a strong Renner-Teller vibronic coupling of bending vibrations in the 4pi* excited states with a bent equilibrium geometry. The anions (S-, C- and O-) are observed both below and above the thresholds. The fact that the anion production is suppressed at shape resonances allows the anions to serve as a suggestive and complementary tool for identifying above-threshold structures in the OCS photoabsorption spectra. Post-collision-interaction effects in OCS and locality of the lowest unoccupied molecular orbital 4pi* at the sulfur atom are also evidenced in the anion spectra

    Mrub_1283, Mrub_1284 and Mrub_1285 encode for a glycine/betaine ABC transporter and are orthologs of \u3cem\u3eE. coli\u3c/em\u3e proV, proW and proX

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    ABC transporters are essential for cellular transport; contribute to maintain the homeostasis of the cells. Generally, ABC transporters are multi-subunit; contain essential cytoplasmic factors which are critical to ATP hydrolysis activity. In this paper, we would like to take a closer look to Mrub_1283, Mrub_1284 and Mrub_1285, three consecutive genes in Meiothermus ruber genome. We hypothesize that these genes are in the same operon and encode for ABC glycine/ betaine transporters. To confirm our hypothesis, we utilizes several bioinformatics tools to predict the potential function of Mrub_1283, Mrub_1284 and Mrub_1285 and to search for their orthologs in Escherichia coli genome. From the data of different bioinformatics tools, Mrub_1283, Mrub_1284 and Mrub_1285 are showed to be orthologous to proV, proW and proX genes in E.coli genomes. As a result, Mrub_1283, Mrub_1284 and Mrub_1285 have the same function with proV, proW and proX therefore encode for ABC glycine/ betaine transporters in Meiothermus ruber

    FGF dependent regulation of Zfhx1b gene expression promotes the formation of definitive neural stem cells in the mouse anterior neurectoderm

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    <p>Abstract</p> <p>Background</p> <p>Mouse definitive neural stem cells (NSCs) are derived from a population of LIF-responsive primitive neural stem cells (pNSCs) within the neurectoderm, yet details on the early signaling and transcriptional mechanisms that control this lineage transition are lacking. Here we tested whether FGF and Wnt signaling pathways can regulate <it>Zfhx1b </it>expression to control early neural stem cell development.</p> <p>Results</p> <p>By microinjecting FGF8b into the pro-amniotic cavity <it>ex vivo </it>at 7.0 days post-coitum (dpc) and culturing whole embryos, we demonstrate that neurectoderm-specific gene expression (for example, <it>Sox2</it>, <it>Nestin</it>, <it>Zfhx1b</it>) is increased, whereas Wnt3a represses neurectoderm gene expression. To determine whether FGF signaling also mediates the lineage transition from a pNSC to a NSC, 7.0-dpc embryos were microinjected with either FGF8b or inhibitors of the FGF receptor-MAP kinase signaling pathway <it>ex vivo</it>, cultured as whole embryos to approximately 8.5 dpc and assayed for clonal NSC colony formation. We show that pre-activation of FGF signaling in the anterior neurectoderm causes an increase in the number of colony forming NSCs derived later from the anterior neural plate, whereas inhibition of FGF signaling significantly reduces the number of NSC colonies. Interestingly, inhibition of FGF signaling causes the persistence of LIF-responsive pNSCs within the anterior neural plate and over-expression of <it>Zfhx1b </it>in these cells is sufficient to rescue the transition from a LIF-responsive pNSC to an FGF-responsive NSC.</p> <p>Conclusion</p> <p>Our data suggest that definitive NSC fate specification in the mouse neurectoderm is facilitated by FGF activation of <it>Zfhx1b</it>.</p

    INNOVATIONS OF VIETNAMESE PROCESSING AND MANUFACTURING ENTERPRISES IN THE CURRENT CONTEXT

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    New technologies create new ways of sourcing to meet the needs of previously traditional markets. The new demands for production and consumption and changing consumer expectations require businesses to change their production, business, design, marketing, and product distribution methods. With globalization taking place more and more strongly and the emergence of the 4.0 industrial revolution, innovation creates a competitive advantage for the country and businesses. In Vietnam, the processing and manufacturing industry has played an essential role in the economy's driving force. This article aims to assess the role and status of innovation for the survival and development of processing enterprises in the Covid–19 epidemic Keywords: Innovation, Technology, Competition, Processing, Manufacturing Enterprises

    From Laborer to Learner: The Experiences of Former Factory Workers in a Developmental Education Program

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    This study reports on a qualitative, case study of a learning community approach to developmental education for dislocated workers. The findings suggest that participants rework a sense of themselves as learners, mediated by their experience of liminality and the emergence of communitas within the group
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