859 resultados para Social and spatial dynamics


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This is an empirical study with theoretical interpretation and elaboration simultaneously on the migration process and the related spatial development in contemporary China. In so doing, there is always a combination of series of studies of the modernization of the migrants themselves with accumulation of forms of capital and changes of lebenswelt (life world) as well as the regions of their origins by the effective use of the gained resources from outgoing migration and remigration. With great efforts made to put the issues together for analysis, the author has taken three approaches to the study based on the political and economic institutional arrangements, the field work data and the elaboration of respective findings. First, as the analytical parts of the institutional changes, which have gone through the whole research, many of the policies from state level to townships involved in the migration, remigration and spatial development have been interpreted with Chinese political and cultural insight. The making of these, as the means of understanding the contexts of macro level and micro level cases is served as key linkages between scholarly imagination and social reality. Indeed most of the discussions made to explain the phenomena such as the sudden upsurge of migration flows, the emergence of three generations, the strong and weak trends of remigration as well as the related spatial development planning, etc are mainly due to the domination, at least the impact of governments decision-making in spite of growing market functioning in often operative manners. Secondly, case studies of the effects of migration and remigration are carried out between the years of 1995 and 2005 in the costal urban regions as designations and the interior rural regions as origins. Conducted mainly by the author, the cases drawn in the research focus on the process of migration with an accumulation of forms of capital away from home and the effective use of the resources flowing back to home areas. As a result, ways of accumulation and utilization of the economic, social and cultural capital are described and interpreted in terms of the development and modernization of both the migrants themselves and the regions where they come out from or move to in the future. Thirdly, in accordance with the findings generated from the cases, the author proposes in the final chapter an important argumentation as conclusion that the duel social-economic structure will inevitably be broken up and reformulated with flows of migrants and forms of capital they possess as types of future spatial development that will be put into practice. With scenarios and all the other conclusions worked out in the end, the research concludes that the pluralistic spatial development in the condition of constant space flows between regions can be a decisive line of thinking in the process of urbanization, industrialization and modernization in the long run in the future. Since this is an exploratory study of the past and present, the author has left some space open for academic debates and put forward suggestions on the inclusion of future research before implementing policies necessary for migration associated spatial practice and development.

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Purpose The article examines principles of Fair Trade in public procurement in Europe, focusing on legal dimensions related to the European Public Procurement Directives. Design/methodology/approach The article situates public procurement of Fair Trade products in relation to the rise of non-state regulatory initiatives, highlighting how they have entered into new governance dynamics in the public sector and play a part in changing practices in sustainable procurement. A review of legal position on Fair Trade in procurement law is informed by academic research and campaigning experience from the Fair Trade Advocacy Office. Findings Key findings are that the introduction of Fair Trade products into European public procurement has been marked by legal ambiguity, having developed outside comprehensive policy or legal guidelines. Following a 2012 ruling by the Court of Justice of the European Union, it is suggested that the legal position for Fair Trade in procurement has become clearer, and that forthcoming change to the Public Procurement Directives may facilitate the uptake of fair trade products by public authorities. However potential for future expansion of the public sector ‘market’ for Fair Trade is approached with caution: purchasing Fair Trade products as a marker of sustainability, which started to be embedded within procurement practice in the 2000s, is challenged by current European public austerity measures. Research limitations/implications Suggestions for future research include the need for systematic cross-institutional and multi-country comparison of the legal and governance dimensions of procurement practice with regard to Fair Trade. Practical implications A clarification of current state-of-play with regard to legal aspects of fair trade in public procurement of utility for policy and advocacy discussion. Originality/value The article provides needed elaboration on an under researched topic area of value to academia and policy makers.

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Purpose – The purpose of the research was to discover the process of social and environmental report assurance (SERA) and thereby evaluate the benefits, extent of stakeholder inclusivity and/or managerial capture of SERA processes and the dynamics of SERA as it matures. Design/methodology/approach – This paper used semi-structured interviews with 20 accountant and consultant assurors to derive data, which were then coded and analysed, resulting in the identification of four themes. Findings – This paper provides interview evidence on the process of SERA, suggesting that, although there is still managerial capture of SERA, stakeholders are being increasingly included in the process as it matures. SERA is beginning to provide dual-pronged benefits, adding value to management and stakeholders simultaneously. Through the lens of Freirian dialogic theory, it is found that SERA is starting to display some characteristics of a dialogical process, being stakeholder inclusive, demythologising and transformative, with assurors perceiving themselves as a “voice” for stakeholders. Consequently, SERA is becoming an important mechanism for driving forward more stakeholder-inclusive SER, with the SERA process beginning to transform attitudes of management towards their stakeholders through more stakeholder-led SER. However, there remain significant obstacles to dialogic SERA. The paper suggests these could be removed through educative and transformative processes driven by assurors. Originality/value – Previous work on SERA has involved predominantly content-based analysis on assurance statements. However, this paper investigates the details of the SERA process, for the first time using qualitative interview data.

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This study investigates the logics or values that shape the social and environmental reporting (SER) and SER assurance (SERA) process. The influence of logics is observed through a study of the conceptualisation and operationalisation of the materiality concept by accounting and non-accounting assurors and their assurance statements. We gathered qualitative data from interviews with both accounting and non-accounting assurors. We analysed the interplay between old and new logics that are shaping materiality as a reporting concept in SER. SER is a rich field in which to study the dynamics of change because it is a voluntary, unregulated, qualitative reporting arena. It has a broad, stakeholder audience, where accounting and non-accounting organisations are in competition. There are three key findings. First, the introduction of a new, stakeholder logic has significantly changed the meaning and role of materiality. Second, a more versatile, performative, social understanding of materiality was portrayed by assurors, with a forward-looking rather than a historic focus. Third, competing logics have encouraged different beliefs about materiality, and practices, to develop. This influenced the way assurors theorised the concept and interpreted outcomes. A patchwork of localised understandings of materiality is developing. Policy implications both in SERA and also in financial audit are explored.

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The transition to turbulence (spatio-temporal chaos) in a wide class of spatially extended dynamical system is due to the loss of transversal stability of a chaotic attractor lying on a homogeneous manifold (in the Fourier phase space of the system) causing spatial mode excitation Since the latter manifests as intermittent spikes this has been called a bubbling transition We present numerical evidences that this transition occurs due to the so called blowout bifurcation whereby the attractor as a whole loses transversal stability and becomes a chaotic saddle We used a nonlinear three-wave interacting model with spatial diffusion as an example of this transition (C) 2010 Elsevier B V All rights reserved

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The bubble crab Dotilla fenestrata forms very dense populations on the sand flats of the eastern coast of Inhaca Island, Mozambique, making it an interesting biological model to examine spatial distribution patterns and test the relative efficiency of common sampling methods. Due to its apparent ecological importance within the sandy intertidal community, understanding the factors ruling the dynamics of Dotilla populations is also a key issue. In this study, different techniques of estimating crab density are described, and the trends of spatial distribution of the different population categories are shown. The studied populations are arranged in discrete patches located at the well-drained crests of nearly parallel mega sand ripples. For a given sample size, there was an obvious gain in precision by using a stratified random sampling technique, considering discrete patches as strata, compared to the simple random design. Density average and variance differed considerably among patches since juveniles and ovigerous females were found clumped, with higher densities at the lower and upper shore levels, respectively. Burrow counting was found to be an adequate method for large-scale sampling, although consistently underestimating actual crab density by nearly half. Regression analyses suggested that crabs smaller than 2.9 mm carapace width tend to be undetected in visual burrow counts. A visual survey of sampling plots over several patches of a large Dotilla population showed that crab density varied in an interesting oscillating pattern, apparently following the topography of the sand flat. Patches extending to the lower shore contained higher densities than those mostly covering the higher shore. Within-patch density variability also pointed to the same trend, but the density increment towards the lowest shore level varied greatly among the patches compared.

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Topography has been reported to be the major factor ruling the spatial distribution of Acrisols, Plinthosols and Gleysols on the seasonally flooded, low elevation plateaux of the upper Amazon basin occupied by Tertiary (Ica & Solimoes) sediments. In this study, detailed morphological and mineralogical investigations conducted in a representative 25-ha site were combined with hydro-geochemical data to relate the vertical and lateral soil differentiations observed to the hydro-geological history of that part of the basin. As a result of the uplift of the Andes, several cuts in the extensive Tertiary marshlands have formed, at first, slightly incised plateaux of low elevation. There, weathering under hot and humid climates would have generated a reddish, freely drained and bioturbated topsoil layer and the vertical differentiation in subsoil sediments of a plinthite over an iron-depleted mottled clay. The second episode of soil differentiation is linked to the replacement of the forest by a savannah under the drier climates of the late Pleistocene, which favours surface runoff and the infill of the incisions by fine particles. This infill, combined with the return to the present humid climate, has then enabled the local groundwater to rise on the plateaux and to generate episaturation at the topsoil/subsoil transition close to the depressions. Nowadays, ferrous iron is released from the partly iron-depleted topsoil weathering front at high water levels during the rainy seasons. It moves from footslope to low-lying positions and from top to bottom in the soil profile according to the groundwater dynamics. The present general trend is thus to the lateral export of iron at high water levels due to subsurface and overland flows, its vertical transfer during the recession of the groundwater and accumulation in a nodular plinthite. In the latter, ferrous iron is adsorbed onto its softest iron masses where it feeds the neoformation of ferrihydrite that rapidly dehydrates into haematite.

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How individual-level movement decisions in response to habitat edges influence population-level patterns of persistence and spread of a species is a major challenge in spatial ecology and conservation biology. Here, we integrate novel insights into edge behavior, based on habitat preference and movement rates, into spatially explicit growth-dispersal models. We demonstrate how crucial ecological quantities (e.g., minimal patch size, spread rate) depend critically on these individual-level decisions. In particular, we find that including edge behavior properly in these models gives qualitatively different and intuitively more reasonable results than those of some previous studies that did not consider this level of detail. Our results highlight the importance of new empirical work on individual movement response to habitat edges. © 2013 by The University of Chicago.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The wetlands of south-central Nebraska’s Rainwater Basin region are considered of international importance as a habitat for millions of migratory birds, but are being endangered by agricultural practices. The Rainwater Basin extends across 17 counties and covers 4,000 square miles. The purpose of this study was to assemble baseline chemical data for several representative wetlands across the Rainwater Basin region, and determine the use of these chemical data for investigating groundwater recharge. Eight representative wetlands were chosen across the Rainwater Basin to monitor surface and groundwater chemistry. At each site, a shallow well and deep well were installed and sampled once in the summer of 2009 and again in the spring of 2010. Wetland surface water was sampled monthly from April, 2009 to May, 2010. Waters were analyzed for major ions, nutrients, pesticides and oxygen-18 and deuterium isotopes at the University of Nebraska Water Sciences Laboratory. Geochemical analysis of surface waters presents a range of temporal and spatial variations. Wetlands had variable water volumes, isotopic compositions, ion chemistries and agricultural contaminant levels throughout the year and, except for a few trends, theses variations cannot be predicted with certainty year-to-year or wetland-to-wetland. Isotopic compositions showed evaporation was a contributor to water loss, and thus, did impact water chemistry. Surface water nitrate concentrations ranged from <0.10 to 4.04 mg/L. The nitrate levels are much higher in the groundwater, ranging from <0.10 to 18.4 mg/L, and are of concern because they are found above the maximum contaminant level (MCL) of 10 mg/L. Atrazine concentrations in surface waters ranged from <0.05 to 10.3 ppb. Groundwater atrazine concentrations ranged from <0.05 to 0.28 ppb. The high atrazine concentrations in surface waters are of concern as they are above the MCL of 3 ppb, and the highest levels occur during the spring bird migration. Most sampled groundwaters had detectable tritium indicating a mix of modern (<5 to 10 years old) and submodern (older than 1950s) recharge. The groundwater also had differences in chemical and isotope composition, and in some cases, increased nitrate concentrations, between the two sampling periods. Modern groundwater tritium ages and changes in groundwater chemical and isotopic compositions may indicate connections with surface waters in the Rainwater Basin.

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The transient and equilibrium properties of dynamics unfolding in complex systems can depend critically on specific topological features of the underlying interconnections. In this work, we investigate such a relationship with respect to the integrate-and-fire dynamics emanating from a source node and an extended network model that allows control of the small-world feature as well as the length of the long-range connections. A systematic approach to investigate the local and global correlations between structural and dynamical features of the networks was adopted that involved extensive simulations (one and a half million cases) so as to obtain two-dimensional correlation maps. Smooth, but diverse surfaces of correlation values were obtained in all cases. Regarding the global cases, it has been verified that the onset avalanche time (but not its intensity) can be accurately predicted from the structural features within specific regions of the map (i.e. networks with specific structural properties). The analysis at local level revealed that the dynamical features before the avalanches can also be accurately predicted from structural features. This is not possible for the dynamical features after the avalanches take place. This is so because the overall topology of the network predominates over the local topology around the source at the stationary state.