72 research outputs found
Statistical Mechanics of Glass Formation in Molecular Liquids with OTP as an Example
We extend our statistical mechanical theory of the glass transition from
examples consisting of point particles to molecular liquids with internal
degrees of freedom. As before, the fundamental assertion is that super-cooled
liquids are ergodic, although becoming very viscous at lower temperatures, and
are therefore describable in principle by statistical mechanics. The theory is
based on analyzing the local neighborhoods of each molecule, and a statistical
mechanical weight is assigned to every possible local organization. This
results in an approximate theory that is in very good agreement with
simulations regarding both thermodynamical and dynamical properties
Corresponding States of Structural Glass Formers
The variation with respect to temperature T of transport properties of 58
fragile structural glass forming liquids (68 data sets in total) are analyzed
and shown to exhibit a remarkable degree of universality. In particular,
super-Arrhenius behaviors of all super-cooled liquids appear to collapse to one
parabola for which there is no singular behavior at any finite temperature.
This behavior is bounded by an onset temperature To above which liquid
transport has a much weaker temperature dependence. A similar collapse is also
demonstrated, over the smaller available range, for existing numerical
simulation data.Comment: 6 pages, 2 figures. Updated References, Table Values, Submitted for
Publicatio
Impaired Spleen Formation Perturbs Morphogenesis of the Gastric Lobe of the Pancreas
Despite the extensive use of the mouse as a model for studies of pancreas development and disease, the development of the gastric pancreatic lobe has been largely overlooked. In this study we use optical projection tomography to provide a detailed three-dimensional and quantitative description of pancreatic growth dynamics in the mouse. Hereby, we describe the epithelial and mesenchymal events leading to the formation of the gastric lobe of the pancreas. We show that this structure forms by perpendicular growth from the dorsal pancreatic epithelium into a distinct lateral domain of the dorsal pancreatic mesenchyme. Our data support a role for spleen organogenesis in the establishment of this mesenchymal domain and in mice displaying perturbed spleen development, including Dh +/â, Bapx1â/â and Sox11â/â, gastric lobe development is disturbed. We further show that the expression profile of markers for multipotent progenitors is delayed in the gastric lobe as compared to the splenic and duodenal pancreatic lobes. Altogether, this study provides new information regarding the developmental dynamics underlying the formation of the gastric lobe of the pancreas and recognizes lobular heterogeneities regarding the time course of pancreatic cellular differentiation. Collectively, these data are likely to constitute important elements in future interpretations of the developing and/or diseased pancreas
Globalization, multinationals and institutional diversity
This article aims to explore the impact of globalization and in particular multinationals on diversity within national varieties of capitalism. Do the actions of multinationals create more diversity within national systems, do they reduce diversity or do they have relatively little impact on diversity within national systems? The article argues that there are distinctive structures of institutional diversity across different national systems. Therefore, the question is not how do MNCs impact on institutional diversity per se but how do they impact on these different structures of diversity? In order to develop this argument, the paper also differentiates types of multinational. The article uses distinction between market-seeking, resource-seeking, efficiency-seeking and strategic asset-seeking in order to identify a range of different MNC activity across manufacturing, professional and financial sectors. These different sorts of MNC activity vary across time and contexts in terms of their significance. The article looks in detail at four different models of capitalism and examines how the entry of different sorts of multinationals with distinctive objectives impacts on the relationships between key social actors which underpin and reinforce these models. In this way, it suggests how institutional diversity within different types of capitalism may evolve under the impact of MNCs and globalization
Psip1/p52 regulates posterior Hoxa genes through activation of lncRNA Hottip
Long noncoding RNAs (lncRNAs) have been implicated in various biological functions including the regulation of gene expression, however, the functionality of lncRNAs is not clearly understood and conflicting conclusions have often been reached when comparing different methods to investigate them. Moreover, little is known about the upstream regulation of lncRNAs. Here we show that the short isoform (p52) of a transcriptional co-activatorâPC4 and SF2 interacting protein (Psip1), which is known to be involved in linking transcription to RNA processing, specifically regulates the expression of the lncRNA Hottipâlocated at the 5â end of the Hoxa locus. Using both knockdown and knockout approaches we show that Hottip expression is required for activation of the 5â Hoxa genes (Hoxa13 and Hoxa10/11) and for retaining Mll1 at the 5â end of Hoxa. Moreover, we demonstrate that artificially inducing Hottip expression is sufficient to activate the 5â Hoxa genes and that Hottip RNA binds to the 5â end of Hoxa. By engineering premature transcription termination, we show that it is the Hottip lncRNA molecule itself, not just Hottip transcription that is required to maintains active expression of posterior Hox genes. Our data show a direct role for a lncRNA molecule in regulating the expression of developmentally-regulated mRNA genes in cis
The dynamics of spleen morphogenesis
AbstractThe mammalian spleen has important functions in immunity and haematopoiesis but little is known about the events that occur during its early embryonic development. Here we analyse the origin of the cells that gives rise to the splenic mesenchyme and the process by which the precursors assume their position along the left lateral side of the stomach. We report a highly conserved regulatory element that regulates the Nkx2-5 gene throughout early spleen development. A transgenic mouse line carrying this element driving a reporter gene was used to show that morphogenesis of the spleen initiates bilaterally and posterior to the stomach, before the splenic precursors grow preferentially leftward. In addition the transgenic line was used in an organ culture system to track spleen precursor cells during development. Spleen cells were shown to move from the posterior mesenchyme and track along the left side of the stomach. Removal of tissue from the anterior stomach resulted in splenic cells randomly scattering suggesting a guidance role for the anterior stomach. Using a mouse line carrying a conditional Cre recombinase to mark early precursor cell populations, the spleen was found to derive from posterior mesenchyme distinct from the closely adjacent stomach mesenchyme
The Role of Spatially Controlled Cell Proliferation in Limb Bud Morphogenesis
Oriented cell behaviors likely have a more important role in limb bud elongation during development than previously suggested by the âgrowth-based morphogenesisâ hypothesis
Gendering the careers of young professionals: some early findings from a longitudinal study. in Organizing/theorizing: developments in organization theory and practice
Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce â not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales
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