35 resultados para Galois extensions of local commutative rings
em Aston University Research Archive
Resumo:
This paper reports on a recent pilot project by the English government aimed at introducing 'single pot' funding for local voluntary and community groups. It finds that implementation difficulties undermined the success of the scheme. Moreover, whilst local voluntary and community groups were initially enthusiastic about the scheme, this was eroded both by the shortfall in funding for the initiative and by conflicting priorities for it from its national and regional flinders and from local groups.
Resumo:
Previous research suggests that changing consumer and producer knowledge structures play a role in market evolution and that the sociocognitive processes of product markets are revealed in the sensemaking stories of market actors that are rebroadcasted in commercial publications. In this article, the authors lend further support to the story-based nature of market sensemaking and the use of the sociocognitive approach in explaining the evolution of high-technology markets. They examine the content (i.e., subject matter or topic) and volume (i.e., the number) of market stories and the extent to which content and volume of market stories evolve as a technology emerges. Data were obtained from a content analysis of 10,412 article abstracts, published in key trade journals, pertaining to Local Area Network (LAN) technologies and spanning the period 1981 to 2000. Hypotheses concerning the evolving nature (content and volume) of market stories in technology evolution are tested. The analysis identified four categories of market stories - technical, product availability, product adoption, and product discontinuation. The findings show that the emerging technology passes initially through a 'technical-intensive' phase whereby technology related stories dominate, through a 'supply-push' phase, in which stories presenting products embracing the technology tend to exceed technical stories while there is a rise in the number of product adoption reference stories, to a 'product-focus' phase, with stories predominantly focusing on product availability. Overall story volume declines when a technology matures as the need for sensemaking reduces. When stories about product discontinuation surface, these signal the decline of current technology. New technologies that fail to maintain the 'product-focus' stage also reflect limited market acceptance. The article also discusses the theoretical and managerial implications of the study's findings. © 2002 Elsevier Science Inc. All rights reserved.
Resumo:
Luminance changes within a scene are ambiguous; they can indicate reflectance changes, shadows, or shading due to surface undulations. How does vision distinguish between these possibilities? When a surface painted with an albedo texture is shaded, the change in local mean luminance (LM) is accompanied by a similar modulation of the local luminance amplitude (AM) of the texture. This relationship does not necessarily hold for reflectance changes or for shading of a relief texture. Here we concentrate on the role of AM in shape-from-shading. Observers were presented with a noise texture onto which sinusoidal LM and AM signals were superimposed, and were asked to indicate which of two marked locations was closer to them. Shape-from-shading was enhanced when LM and AM co-varied (in-phase), and was disrupted when they were out-of-phase. The perceptual differences between cue types (in-phase vs out-of-phase) were enhanced when the two cues were present at different orientations within a single image. Similar results were found with a haptic matching task. We conclude that vision can use AM to disambiguate luminance changes. LM and AM have a positive relationship for rendered, undulating, albedo textures, and we assess the degree to which this relationship holds in natural images. [Supported by EPSRC grants to AJS and MAG].
Resumo:
Measurements were carried out to determine local coefficients of heat transfer in short lengths of horizontal pipe, and in the region of an discontinuity in pipe diameter. Laminar, transitional and turbulent flow regimes were investigated, and mixtures of propylene glycol and water were used in the experiments to give a range of viscous fluids. Theoretical and empirical analyses were implemented to find how the fundamental mechanism of forced convection was modified by the secondary effects of free convection, temperature dependent viscosity, and viscous dissipation. From experiments with the short tube it was possible to determine simple empirical relationships describing the axial distribution of the local 1usselt number and its dependence on the Reynolds and Prandtl numbers. Small corrections were made to account for the secondary effects mentioned above. Two different entrance configurations were investigated to demonstrate how conditions upstream could influence the heat transfer coefficients measured downstream In experiments with a sudden contraction in pipe diameter the distribution of local 1u3se1t number depended on the Prandtl number of the fluid in a complicated way. Graphical data is presented describing this dependence for a range of fluids indicating how the local Nusselt number varied with the diameter-ratio. Ratios up to 3.34:1 were considered. With a sudden divergence in pipe diameter, it was possible to derive the axial distribution of the local Nusse1t number for a range of Reynolds and Prandtl numbers in a similar way to the convergence experiments. Difficulty was encountered in explaining some of the measurements obtained at low Reynolds numbers, and flow visualization techniques wore used to determine the complex flow patterns which could lead to the anomalous results mentioned. Tests were carried out with divergences up to 1:3.34 to find the way in which the local Nusselt number varied with the diameter ratio, and a few experiments were carried out with very large ratios up .to 14.4. A limited amount of theoretical analysis of the 'divergence' system was carried out to substantiate certain explanations of the heat transfer mechanisms postulated.
Resumo:
Certain species of crustose lichens have concentrically zoned margins which probably represent yearly growth rings. These marginal growth rings offer an alternative method of studying annual growth fluctuations, establishing growth rate-size curves, and determining the age of thalli for certain crustose species. Hence, marginal growth rings represent a potentially valuable, unexploited, tool in lichenometry. In a preliminary study, we measured the widths of the successive marginal rings in 25 thalli of Ochrolechia parella (L.) Massal., growing at a maritime site in north Wales. Mean ring widths of all thalli varied from a minimum of 1.02 mm (the outermost ring) to a maximum of 2.06 mm (the third ring from the margin). There is some suggestion that marginal ring width and thallus size are positively correlated; and hence that growth rates increase in larger thalli in this small population. In a further study on recently exposed bedrock adjacent to Breidalon, SE Iceland, we examined the potential for using marginal growth rings to estimate thallus age of a lichen tentatively identified as a Rhizocarpon (possibly R. concentricum (Davies) Beltram.) and thus confirm the timing of surface exposure (c. 50 years). Collectively, these results suggest: 1) the measurement of marginal rings is a possible alternative method of studying the growth of crustose lichens; 2) O. parella may grow differently to other crustose species, exhibiting a rapidly increasing radial growth rate in thalli >40 mm; 3) where lichens with marginal rings grow on recently exposed surfaces (<60 yrs), minimum age estimates can be made using growth rings as an in situ indication of lichen growth rate; 4) it is suggested that this phenomenon could provide a valuable, previously unexploited, in situ lichenometric-dating tool in areas lacking calibration control.
Resumo:
The first part of the thesis compares Roth's method with other methods, in particular the method of separation of variables and the finite cosine transform method, for solving certain elliptic partial differential equations arising in practice. In particular we consider the solution of steady state problems associated with insulated conductors in rectangular slots. Roth's method has two main disadvantages namely the slow rate of convergence of the double Fourier series and the restrictive form of the allowable boundary conditions. A combined Roth-separation of variables method is derived to remove the restrictions on the form of the boundary conditions and various Chebyshev approximations are used to try to improve the rate of convergence of the series. All the techniques are then applied to the Neumann problem arising from balanced rectangular windings in a transformer window. Roth's method is then extended to deal with problems other than those resulting from static fields. First we consider a rectangular insulated conductor in a rectangular slot when the current is varying sinusoidally with time. An approximate method is also developed and compared with the exact method.The approximation is then used to consider the problem of an insulated conductor in a slot facing an air gap. We also consider the exact method applied to the determination of the eddy-current loss produced in an isolated rectangular conductor by a transverse magnetic field varying sinusoidally with time. The results obtained using Roth's method are critically compared with those obtained by other authors using different methods. The final part of the thesis investigates further the application of Chebyshdev methods to the solution of elliptic partial differential equations; an area where Chebyshev approximations have rarely been used. A poisson equation with a polynomial term is treated first followed by a slot problem in cylindrical geometry.
Resumo:
This research focuses on two groups of local companies; namely, high-growth local companies and other local companies, to examine and compare the influence of utilising governmental initiatives, servicing foreign MNCs and internationalisation on their strategic planning process. The theme of this thesis argues that the approach of an organisation towards strategic planning is not only determined by the internal influences; namely, its firm size and the planning behaviour and attitude of an entrepreneur, as revealed in the literature, but it can also be affected by external influences. The theoretical contribution of this research determines this unique situation in Singapore, and tests the robustness of the conventional models of planning in smaller companies. As a result of the external influences, this study reveals that local companies are more likely to undertake a much more formal strategic planning than the conventional Western literature and models would indicate. High-growth local companies, in comparison, however, had undertaken a more formal and rigorous strategic planning process than other local companies.
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This research studies two cases of implementation of alternative strategies for municipal government reform in Brazil, decentralisation and People's Councils. The aim is to answer the following general question: `Can decentralisation and People's Councils be a means for democratization of municipal government in Brazil?'. The hypothesis is that initiatives to reform Brazilian municipal governments face problems that are characteristic of the Brazilian political and administrative reality. These problems are considered obstacles for the development of those initiatives and accordingly, for democratization of municipal government in Brazil. After an introduction and outline in Chapter One, Chapter Two discusses four main theories concerning local government. Chapter Three discusses decentralisation and People's Councils are discussed in Chapter Four. Chapter Five presents a historical, political and economic overview of Brazil. Chapter Six deals with Brazilian Federalism and Municipal Government. The main aspects of the Municipal Government are presented as well as the development of municipal autonomy through the various Federal Constitutions and cases of People's Councils and decentralisation in municipalities in Brazil. Chapter Seven presents the political parties responsible for the initiatives, the PSDB (Brazilian Social Democratic Party) in the case of decentralisation, and the PT (Workers' Party) in the case of People's Councils. In Chapter Eight the research strategy and the data collection techniques are described. Chapters Nine and Ten present decentralisation implemented by the PSDB in Belo Horizonte, the Minas Gerais state capital and People's Councils introduced by the PT in the town of Ipatinga in the same state. Conclusions are presented in Chapter Eleven and include a comparison and discussion of the two cases. The thesis shows that these experiments with alternative strategies of local government face problems that are generally current in Brazilian political and administrative reality. Those problems are concerned with unwillingness to decentralise power, clientelism, low levels of participation of civil society and the `political' use of the structures implemented.
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This study concerns the production and action of the local mediators nitric oxide (NO) and prostaglandin E2 (PGE2) in the rat gastric mucosa. The major objectives were: (i) to determine which mucosal cell type(s) contained NO synthase activity, (ii) to establish the functional role(s) of NO in the gastric mucosa and (iii) to investigate regulation of gastric PGE2 production. Gastric mucosal cells were isolated by pronase digestion coupled with intermittent calcium chelation and were separated by either density-gradient centrifugation or by counterflow elutriation. The distribution of Ca2+ -dependent NO synthase activity, measured via the conversion of [14C]-L-arginine to [14C]-L- citrulline, paralleled the distribution of mucous cells in elutriated fractions. Pre-treatment of rats with lipopolysaccharide caused the induction of Ca2+ -independent NO synthase in the elutriator fractions enriched with mucous cells. Incubation of isolated cells with the NO donor isosorbide dinitrate (ISDN) produced a concentration-dependent increase in the guanosine 3',-5'-cyclic monophosphate (cGMP) content which was accompanied by a concentration-dependent increase in release of immunoreactive mucin. Intragastric administration of ISDN of dibutyryl cGMP in vivo increased the thickness of the mucus layer overlying the gastric mucosa. The NO donor S-nitroso-N-acetylpenicillamine (SNAP) produced a concentration-dependent inhibition (IC50 247 μM) of histamine-stimulated aminopyrine accumulation, a measure of secretory activity, in cell suspensions containing > 80% parietal cells. SNAP increased the cGMP content of the suspension but did not decrease cellular viability, glucose oxidation or adenosine 3',5'-cyclic monophosphate content. The inhibitory effect of SNAP was observed in permeabilised cells stimulated with ATP and was stereospecifically blocked by preincubation with Rp-8-bromoguanosine 3'-5'-monophosphorothioate, which inhibits activation of cGMP-dependent protein kinase. Stimulation of PGE2 release by bradykinin in a low density cell fraction, enriched with parietal cells and devoid of vascular endothelial cells and macrophages, involved a bradykinin B1 receptor. In summary, NO synthase activity is probably present in gastric mucous epithelial cells. NO may promote mucus secretion by elevation of cGMP. NO donors inhibit acid secretion at a specific site and their action may involve cGMP. The bradykinin B1 receptor is involved with PGE2 production in the gastric mucosa.
Resumo:
We show that, with suitable optics in the arm of a Michelson interferometer, orthogonal galvo-scanning mirrors build a sampling function in the form of Newton rings when the two interferometer arms are matched. Using a low-coherence source, one can obtain transversal depth-resolved images. A fast display procedure using a storage oscilloscope was devised based on this method.
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We introduce a continuum model describing data losses in a single node of a packet-switched network (like the Internet) which preserves the discrete nature of the data loss process. By construction, the model has critical behavior with a sharp transition from exponentially small to finite losses with increasing data arrival rate. We show that such a model exhibits strong fluctuations in the loss rate at the critical point and non-Markovian power-law correlations in time, in spite of the Markovian character of the data arrival process. The continuum model allows for rather general incoming data packet distributions and can be naturally generalized to consider the buffer server idleness statistics.
Resumo:
The modernization of local government is central to the government’s plans to revitalize the UK’s constitutional arrangements. Implicitly managerialist, the modernizing local government project also contains centralist and localist themes. Translated into policy, these themes are articulated as leadership, community, democracy and regulation. However, these elements are potentially contradictory and may produce tensions in the project that may be difficult to resolve. By reviewing the government’s aims to promote leadership, community and democracy in local government, it is also argued that the planned modernization of local government will extend further and into new areas the regulation of local authorities.