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Particular Regions (particular + regions)
Selected AbstractsAnalysis of epitaxial laterally overgrown silicon structures by high resolution x-ray rocking curve imagingCRYSTAL RESEARCH AND TECHNOLOGY, Issue 5 2009B. Heimbrodt Abstract Spatially resolved rocking curve imaging has been used to analyze laterally overgrown silicon layers grown by liquid phase epitaxy. We were able to study both the overgrown layer as well as the strain fluctuations of the Si substrate underneath by means of a tabletop x-ray topographic setup. The strain-field analysis reveals relative changes of the lattice parameter up to 3.5×10 -6 in the silicon substrate underneath the overgrown layer in particular regions and a down bending of both wings of the epitaxial overgrown layers. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Differential levels of tissue hypoxia in the developing chicken heartDEVELOPMENTAL DYNAMICS, Issue 1 2006Jamie Wikenheiser Abstract Tissue hypoxia plays a critical role in normal development, including cardiogenesis. Previously, we showed that oxygen concentration, as assessed by the hypoxia indicator EF5, is lowest in the outflow tract (OFT) myocardium of the developing chicken heart and may be regulating events in OFT morphogenesis. In this study, we identified additional areas of the embryonic chicken heart that were intensely positive for EF5 within the myocardium in discrete regions of the atrial wall and the interventricular septum (IVS). The region of the IVS that is EF5-positive includes a portion of the developing central conduction system identified by HNK-1 co-immunostaining. The EF5 positive tissues were also specifically positive for nuclear-localized hypoxia inducible factor 1, (HIF-1,), the oxygen-sensitive component of the hypoxia inducible factor 1 (HIF-1) heterodimer. The pattern of the most intensely EF5-stained myocardial regions of the atria and IVS resemble the pattern of the major coronary vessels that form in later stages within or immediately adjacent to these particular regions. These vessels include the sinoatrial nodal artery that is a branch of the right coronary artery within the atrial wall and the anterior/posterior interventricular vessels of the IVS. These findings indicate that a portion of the developing central conduction system and the patterning of coronary vessels may be subject to a level of regulation that is dependent on differential oxygen concentration within cardiac tissues and subsequent HIF-1 regulation of gene expression. Developmental Dynamics 235:115,123, 2006. © 2005 Wiley-Liss, Inc. [source] Knowledge Networks in an Uncompetitive Region: SME Innovation and GrowthGROWTH AND CHANGE, Issue 2 2009ROBERT HUGGINS ABSTRACT Knowledge networks are now recognised as a crucial element underlying the economic success and competitiveness of geographic locations, in particular regions. The aim of this paper is to assess the types of knowledge networks utilised and formed by knowledge-based small- and medium-sized enterprises (SMEs) in the relatively uncompetitive regional setting of Yorkshire and Humberside in the UK. It explores the relationship between knowledge networking activity and the levels of innovation and growth achieved by these SMEs. It is found that SMEs tend to utilise and value more knowledge networks with actors outside the region. However, more innovative SMEs possess a balance of inside and outside the region knowledge networks. Knowledge networking activity is sometimes negatively associated with growth, suggesting that networks with certain actors, such as public sector support agencies, may be formed by SMEs when they are facing competitive pressures. In terms of policy implications, the paper recommends a shift from the cluster policies implemented by many regional authorities to a regional innovation systems approach, focusing equally on the regional and more global dimensions of knowledge networks. It is concluded that regional public policy makers need to renew their efforts to support SMEs in creating and sustaining their knowledge networks. [source] Cadherin-8 and N-cadherin differentially regulate pre- and postsynaptic development of the hippocampal mossy fiber pathwayHIPPOCAMPUS, Issue 4 2008Iddil H. Bekirov Abstract Cells sort into regions and groups in part by their selective surface expression of particular classic cadherins during development. In the nervous system, cadherin-based sorting can define axon tracts, restrict axonal and dendritic arbors to particular regions or layers, and may encode certain aspects of synapse specificity. The underlying model has been that afferents and their targets hold in common the expression of a particular cadherin, thereby providing a recognition code of homophilic cadherin binding. However, most neurons express multiple cadherins, and it is not clear whether multiple cadherins all act similarly in shaping neural circuitry. Here we asked how two such cadherins, cadherin-8 and N-cadherin, influence the guidance and differentiation of hippocampal mossy fibers. Using organotypic hippocampal cultures, we find that cadherin-8 regulates mossy fiber fasciculation and targeting, but has little effect on CA3 dendrites. In contrast, N-cadherin regulates mossy fiber fasciculation, but has little impact on axonal growth and targeting. However, N-cadherin is essential for CA3 dendrite arborization. Both cadherins are required for formation of proper numbers of presynaptic terminals. Mechanistically, such differential actions of these two cadherins could, in theory, reflect coupling to distinct intracellular binding partners. However, we find that both cadherins bind ,-catenin in dentate gyrus (DG). This suggests that cadherins may engage different intracellular signaling cascades downstream of ,-catenin, coopt different extracellular binding partners, or target distinct subcellular domains. Together our findings demonstrate that cadherin-8 and N-cadherin are critical for generating the mossy fiber pathway, but that each contributes differentially to afferent and target differentiation, thereby complementing one another in the assembly of a synaptic circuit. © 2007 Wiley-Liss, Inc. [source] Multiple cleavage sites for polymeric immunoglobulin receptorIMMUNOLOGY, Issue 4 2004Masatake Asano Summary Human polymeric immunoglobulin receptor (pIgR) was expressed in baby hamster kidney (BHK) cells using a recombinant vaccinia virus transfection system. Cleavage of pIgR on the cell surface was partially inhibited by the proteinase inhibitor, leupeptin. We addressed the question whether some particular regions of pIgR could affect the efficient cleavage of this molecule, with the following results: (1) a mutant lacking the entire cytoplasmic region resulted in release of secretory component (SC) into the culture supernatant much faster than wild-type; (2) a pIgR mutant lacking the entire extracellular domain 6, the region containing the susceptible cleavage sites, could be cleaved and released as a mutant SC. The transport kinetics of this mutant between endoplasmic reticulum (ER) and Golgi or Golgi and the cell surface was equivalent to wild-type pIgR. Our results indicate that although the main cleavage site is in domain 6, at least one other cleavage site may exist. [source] National growth versus spatial equality?REGIONAL SCIENCE POLICY AND PRACTICE, Issue 1 2008A cautionary note on the new, trade-off' thinking in regional policy discourse national efficiency; regional equity; trade-offs; regional policy Abstract Recently, there has been increasing interest in whether and to what extent the spatial agglomeration or concentration of economic activity and employment in particular regions may actually benefit national growth. The implication is that policies that seek to reduce regional economic inequality may in fact be nationally inefficient: in other words, that a policy ,trade-off' may exist between the pursuit of national growth and the reduction of regional economic disparities. This view has been particularly associated with the so-called ,new economic geography' models, and seems to be circulating in official policy circles. This paper suggests that neither the theoretical argument nor the empirical evidence for a national efficiency-regional equity trade-off are yet convincing, and that until much more research has been undertaken on both fronts policy-makers should exercise caution in appealing to this supposed trade-off notion to justify particular policy choices. [source] The knowledge,space dynamic in the UK bioeconomyAREA, Issue 3 2009Kean Birch The loss of manufacturing employment to lower cost economies has meant that countries like the UK have sought to promote innovation in areas such as biotechnology. The emergence of the ,bioeconomy', however, has been highly uneven, with concentrations of activity in certain countries and particular regions in those countries. In the UK, for example, there are four major concentrations of the bioeconomy. Each of these concentrations exhibit distinct patterns of knowledge and spatial inputs into the innovation process, meaning that it is important to consider the knowledge,space dynamic in and of each region. [source] Rapid changes in clonal lines: the death of a ,sacred cow'BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2003HUGH D. LOXDALE It is well established that asexually reproducing viruses and prokaryotes mutate rapidly. In contrast, the eukaryotic clone is often still treated as if it is genetically homogeneous within and between populations, i.e. that it is assumed to show genetic fidelity. However, such fidelity has rarely been tested empirically using the range of high-resolution molecular markers now available, culminating with direct sequencing of the DNA. If such a biological entity as a ,clone' really did exist, it would be a fantastic entity, differing from everything else known in biology, i.e. it would possess a population mean but no variance for any particular trait. It would not be amenable to selection and adaptive variation and would thus be unchanging in time and space. In this paper, we argue that the general acceptance of clonal fidelity is a scientific convenience, since the rate of asexual reproduction of eukaryotes is not as fast as that of bacteria and hence it is easier to accept fidelity as a ,fact' rather than test for it. We propose that part of the acceptance of fidelity may have a cultural basis and thereby is a kind of ,pre-Darwinian relic'. Instead, a clonal genotype is perhaps largely a function of marker resolution, i.e. dependent on the number and type of markers employed. If this is so and were enough of the genome explored, perhaps each individual within a clone would be found to differ genetically at particular regions of the chromosomes. The question of what constitutes a clone is not just a semantic one and impacts directly on recent attempts to understand and produce ,artificial' clones, especially of mammals. New research is already confirming that mutations and epigenetic influences play a crucial role in the success of cloning attempts. © 2003 The Linnean Society of London. Biological Journal of the Linnean Society, 2003, 79, 3,16. [source] | |||||||||||||