627 research outputs found

    The Carboaryloxy Radical in the Migration of Acyl from Nitrogen to Oxygen in Ortho Aminophenol Derivatives

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    It has been shown, in general, that only one acetyl-benzoyl derivative of ortho aminophenols can be prepared, regardless of the order in which the acyl groups are introduced, and that in this product the benzoyl radical is always found attached to nitrogen. In the recent study of mixed diocyl derivatives of ortho aminophenols in which one of the radicals was the carboaryloxy group, attempts to determine the structure by means of hydrolysis with alkali caused the formation of a carbonylaminophenol

    Theoretical investigation of finite size effects at DNA melting

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    We investigated how the finiteness of the length of the sequence affects the phase transition that takes place at DNA melting temperature. For this purpose, we modified the Transfer Integral method to adapt it to the calculation of both extensive (partition function, entropy, specific heat, etc) and non-extensive (order parameter and correlation length) thermodynamic quantities of finite sequences with open boundary conditions, and applied the modified procedure to two different dynamical models. We showed that rounding of the transition clearly takes place when the length of the sequence is decreased. We also performed a finite-size scaling analysis of the two models and showed that the singular part of the free energy can indeed be expressed in terms of an homogeneous function. However, both the correlation length and the average separation between paired bases diverge at the melting transition, so that it is no longer clear to which of these two quantities the length of the system should be compared. Moreover, Josephson's identity is satisfied for none of the investigated models, so that the derivation of the characteristic exponents which appear, for example, in the expression of the specific heat, requires some care

    Nurturing lifelong learning in communities through the National University of Lesotho: prospects and challenges

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    This paper analyses one aspect of a pan-African action research project called ITMUA (Implementing the Third Mission of Universities in Africa). This particular paper draws on the data from that project to explore the National University of Lesotho’s contribution to lifelong learning in its communities. It provides background information on the ITMUA initiative and analyses interview and focus group responses to two case studies in terms of their contribution to lifelong learning. It uses, as its analytical framework, a modified version of Mbigi’s African perspective on the four De Lors’ ‘pillars’, by adding a fifth pillar, courtesy of Torres. The paper argues that community engagement is a two-way process between universities and their wider constituencies with opportunities for mutual lifelong learning. But there are also challenges of understanding and process which must be addressed if the full range of these lifelong learning pillars is to be accommodated within African contexts. The paper provides an introduction to the history of community engagement in Africa as a university mission, followed by a brief discussion of lifelong learning within African perspectives. After describing the particular context of Lesotho, the concept of community service and community engagement in contemporary African contexts introduces the action research project and the case studies. The final part of the paper presents and discusses the research findings

    Instances and connectors : issues for a second generation process language

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    This work is supported by UK EPSRC grants GR/L34433 and GR/L32699Over the past decade a variety of process languages have been defined, used and evaluated. It is now possible to consider second generation languages based on this experience. Rather than develop a second generation wish list this position paper explores two issues: instances and connectors. Instances relate to the relationship between a process model as a description and the, possibly multiple, enacting instances which are created from it. Connectors refers to the issue of concurrency control and achieving a higher level of abstraction in how parts of a model interact. We believe that these issues are key to developing systems which can effectively support business processes, and that they have not received sufficient attention within the process modelling community. Through exploring these issues we also illustrate our approach to designing a second generation process language.Postprin

    The Victorian Newsletter (Spring 1975)

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    The Victorian Newsletter is sponsored for the English X Group of the Modern Language Association by New York University and Queens College, City University of New York.The Forms of Victorian Fiction / James R. Kincaid -- Method and Moral in George Eliot's Narrative / Elizabeth Ermarth -- Vision and Form: The English Novel and the Emergence of the Short Story / Wendell V. Harris -- Progressive Dubiety: The Discontinuity of Disraeli's Political Trilogy / Daniel R. Schwarz -- Pater's Conception of the Renaissance: From Sources to Personal Ideal / Billie Andrew Inman -- Critical Forum / G. B. Tennyson, Robert O. Preyer, James G. Nelson, and Phyllis Grosskurth -- Recent Publications: A Selected List / Arthur F. Minerof -- English X New

    Physics of Neutron Star Crusts

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    The physics of neutron star crusts is vast, involving many different research fields, from nuclear and condensed matter physics to general relativity. This review summarizes the progress, which has been achieved over the last few years, in modeling neutron star crusts, both at the microscopic and macroscopic levels. The confrontation of these theoretical models with observations is also briefly discussed.Comment: 182 pages, published version available at <http://www.livingreviews.org/lrr-2008-10

    NOX4-dependent ROS production by stromal mammary cells modulates epithelial MCF-7 cell migration

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    BACKGROUND: The influence of the stromal microenvironment on the progression of epithelial cancers has been demonstrated. Unravelling the mechanisms by which stromal cells affect epithelial behaviour will contribute in understanding cellular malignancy. It has been proposed that redox environment has a role in the acquisition of malignancy. In this work, we studied the influence of epithelial cells on the stromal redox status and the consequence of this phenomenon on MCF-7 cell motility. METHODS: We analysed in a co-culture system, the effect of RMF-EG mammary stromal cells on the migratory capacity of MCF-7 cell line. To test whether the NOX-dependent stromal redox environment influences the epithelial migratory behaviour, we knocked down the expression of NOX4 using siRNA strategy. The effect of TGF-b1 on NOX4 expression and activity was analysed by qPCR, and intracellular ROS production was measured by a fluorescent method. RESULTS: Migration of MCF-7 breast epithelial cells was stimulated when co-cultured with RMF-EG cells. This effect depends on stromal NOX4 expression that, in turn, is enhanced by epithelial soluble factors. Pre-treatment of stromal cells with TGF-b1 enhanced this migratory stimulus by elevating NOX4 expression and intracellular ROS production. TGF-b1 seems to be a major component of the epithelial soluble factors that stimulate NOX4 expression. CONCLUSIONS: Our results have identified that an increased stromal oxidative status, mainly provided by an elevated NOX4 expression, is a permissive element in the acquisition of epithelial migratory properties. The capacity of stromal cells to modify their intracellular ROS production, and accordingly, to increase epithelial motility, seems to depend on epithelial soluble factors among which TGF-b1 have a decisive role.This work was supported by the grant (1080196 to JM) from the Fondo Nacional de Ciencia y Tecnologı´a (FONDECYT) of Chile

    Challenges in Using Cultured Primary Rodent Hepatocytes or Cell Lines to Study Hepatic HDL Receptor SR-BI Regulation by Its Cytoplasmic Adaptor PDZK1

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    Background: PDZK1 is a four PDZ-domain containing cytoplasmic protein that binds to a variety of membrane proteins via their C-termini and can influence the abundance, localization and/or function of its target proteins. One of these targets in hepatocytes in vivo is the HDL receptor SR-BI. Normal hepatic expression of SR-BI protein requires PDZK1 - <5% of normal hepatic SR-BI is seen in the livers of PDZK1 knockout mice. Progress has been made in identifying features of PDZK1 required to control hepatic SR-BI in vivo using hepatic expression of wild-type and mutant forms of PDZK1 in wild-type and PDZK1 KO transgenic mice. Such in vivo studies are time consuming and expensive, and cannot readily be used to explore many features of the underlying molecular and cellular mechanisms. Methodology/Principal Findings: Here we have explored the potential to use either primary rodent hepatocytes in culture using 2D collagen gels with newly developed optimized conditions or PDZK1/SR-BI co-transfected cultured cell lines (COS, HEK293) for such studies. SR-BI and PDZK1 protein and mRNA expression levels fell rapidly in primary hepatocyte cultures, indicating this system does not adequately mimic hepatocytes in vivo for analysis of the PDZK1 dependence of SR-BI. Although PDZK1 did alter SR-BI protein expression in the cell lines, its influence was independent of SR-BI’s C-terminus, and thus is not likely to occur via the same mechanism as that which occurs in hepatocytes in vivo. Conclusions/Significance: Caution must be exercised in using primary hepatocytes or cultured cell lines when studying the mechanism underlying the regulation of hepatic SR-BI by PDZK1. It may be possible to use SR-BI and PDZK1 expression as sensitive markers for the in vivo-like state of hepatocytes to further improve primary hepatocyte cell culture conditions.National Institutes of Health (U.S.) (Grant HL052212)National Institutes of Health (U.S.) (Grant HL066105)National Institutes of Health (U.S.) (Grant ES015241)National Institutes of Health (U.S.) (Grant GM068762
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