917 resultados para Change processes
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The authors examine partnerships as a policy strategy for climate change governance in cities in the Global South. Partnerships offer the opportunity to link the actions of diverse actors operating at different scales and, thus, they may be flexible enough to deal with uncertain futures and changing development demands. However, simultaneously, partnerships may lack effectiveness in delivering action at the local level, and may constitute a strategy for some actors to legitimate their objectives in spite of the interests of other partners. Engaging with the specific example of urban governance in Maputo, Mozambique, the authors present an analysis of potential partnerships in this context, in relation to the actors that are willing and able to intervene to deliver climate change action. What, they ask, are the challenges to achieving common objectives in partnerships from the perspective of local residents in informal settlements? The analysis describes a changing context of climate change governance in the city, in which the prospects of access to international finance for climate change adaptation are moving institutional actors towards engaging with participatory processes at the local level. However, the analysis suggests a question about the extent to which local communities are actually perceived as actors with legitimate interests who can intervene in partnerships, and whether their interests are recognised.
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This study investigated the physical processes involved in the development of thunderstorms over southwestern Amazon by hypothesizing causalities for the observed cloud-to-ground lightning variability and the local environmental characteristics. Southwestern Amazon experiences every year a large variety of environmental factors, such as the gradual increase in atmospheric moisture, extremely high pollution due to biomass burning, and intense deforestation, which directly affects cloud development by differential surface energy partition. In the end of the dry period it was observed higher percentages of positive cloud-to-ground (+CG) lightning due to a relative increase in +CG dominated thunderstorms (positive thunderstorms). Positive (negative) thunderstorms initiated preferentially over deforested (forest) areas with higher (lower) cloud base heights, shallower (deeper) warm cloud depths, and higher (lower) convective potential available energy. These features characterized the positive (negative) thunderstorms as deeper (relatively shallower) clouds, stronger (relatively weaker) updrafts with enhanced (decreased) mixed and cold vertically integrated liquid. No significant difference between thunderstorms (negative and positive) and nonthunderstorms were observed in terms of atmospheric pollution, once the atmosphere was overwhelmed by pollution leading to an updraft-limited regime. However, in the wet season both negative and positive thunderstorms occurred during periods of relatively higher aerosol concentration and differentiated size distributions, suggesting an aerosol-limited regime where cloud electrification could be dependent on the aerosol concentration to suppress the warm and enhance the ice phase. The suggested causalities are consistent with the invoked hypotheses, but they are not observed facts; they are just hypotheses based on plausible physical mechanisms.
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We introduce jump processes in R(k), called density-profile processes, to model biological signaling networks. Our modeling setup describes the macroscopic evolution of a finite-size spin-flip model with k types of spins with arbitrary number of internal states interacting through a non-reversible stochastic dynamics. We are mostly interested on the multi-dimensional empirical-magnetization vector in the thermodynamic limit, and prove that, within arbitrary finite time-intervals, its path converges almost surely to a deterministic trajectory determined by a first-order (non-linear) differential equation with explicit bounds on the distance between the stochastic and deterministic trajectories. As parameters of the spin-flip dynamics change, the associated dynamical system may go through bifurcations, associated to phase transitions in the statistical mechanical setting. We present a simple example of spin-flip stochastic model, associated to a synthetic biology model known as repressilator, which leads to a dynamical system with Hopf and pitchfork bifurcations. Depending on the parameter values, the magnetization random path can either converge to a unique stable fixed point, converge to one of a pair of stable fixed points, or asymptotically evolve close to a deterministic orbit in Rk. We also discuss a simple signaling pathway related to cancer research, called p53 module.
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This study covers a period when society changed from a pre-industrial agricultural society to a post-industrial service-producing society. Parallel with this social transformation, major population changes took place. In this study, we analyse how local population changes are affected by neighbouring populations. To do so we use the last 200 years of local population change that redistributed population in Sweden. We use literature to identify several different processes and spatial dependencies in the redistribution between a parish and its surrounding parishes. The analysis is based on a unique unchanged historical parish division, and we use an index of local spatial correlation to describe different kinds of spatial dependencies that have influenced the redistribution of the population. To control inherent time dependencies, we introduce a non-separable spatial temporal correlation model into the analysis of population redistribution. Hereby, several different spatial dependencies can be observed simultaneously over time. The main conclusions are that while local population changes have been highly dependent on the neighbouring populations in the 19th century, this spatial dependence have become insignificant already when two parishes is separated by 5 kilometres in the late 20th century. Another conclusion is that the time dependency in the population change is higher when the population redistribution is weak, as it currently is and as it was during the 19th century until the start of industrial revolution.
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This article examines processes of doing gender during the initiation of students into engineering programs at university level in Sweden. The article draws on interviews with students, focusing on their understandings of gender. The aim is to explore difficulties with and challenges to traditional gender roles in an academic male dominated arena, by using theories of doing and undoing gender. The empirical material reveals the initiation period or ‘reception’ as a phenomenon both reinforcing and challenging traditional orders. The attempts to challenge norms meet resistance, revealing two paradoxes and one dilemma. In the first paradox the formal purpose of the reception (inclusion) is partly at odds with its informal consequence (exclusion of deviations). The second paradox concerns the contradictory effects of the reception. Even though the reception ensures participation of women, it reinforces existing hierarchies including gender inequality. This results in a dilemma, since in order to protect individual safety, there is a taboo on harassing women which then reproduces stable gender stereotypes. So while harassment taints the respect senior students must earn during the reception, the fact that female students exist in the engineering field challenges the established order and opens the way for change.
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This review essay is devoted to a discussion of some central aspects of the Schumpeterian and neo-Schumpeterian approaches to the dynamic processes of development, technological change and innovation. This essay is organised in two parts. In the first, Schumpeter's insightful distinction between circular flow and development is discussed. In the second, some central elements of the neo-Schumpeterian interpretation and extension of Schumpeter's views are critically outlined, special emphasis being placed on some recent attempts to formalize several of his insights on the cyclical dynamics of the processes of technological change and innovation. I should stress that due to space constraints I will focus primarily upon macrotheoretic issues, thus paying only secondary attention to the neo-Schumpeterian literature on the microeconomics of technological change and to the burgeoning empirical developments along those lines.
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In a reccnt paper. Bai and Perron (1998) considcrccl theoretical issues relatec\ lo lhe limiting distriblltion of estimators and test. statist.ics in the linear model \\'ith multiplc struct ural changes. \Ve assess. via simulations, the adequacy of the \'arious I1Iethods suggested. These CO\'er the size and power of tests for structural changes. the cO\'erage rates of the confidence Íntervals for the break dates and the relat.Í\'e merits of methods to select the I1umber of breaks. The \'arious data generating processes considered alIo,,' for general conditions OIl the data and the errors including differellces across segmcll(s. Yarious practical recommendations are made.
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In this paper we study the pricing problem of derivatives written in terms of a two dimensional time{changed L¶evy processes. Then, we examine an existing relation between prices of put and call options, of both the European and the American type. This relation is called put{call duality. It includes as a particular case, the relation known as put{call symmetry. Necessary and su±cient conditions for put{call symmetry to hold are shown, in terms of the triplet of local charac- teristic of the Time{changed L¶evy process. In this way we extend the results obtained in Fajardo and Mordecki (2004) to the case of time{changed Lévy processes.
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This article presents a cooling system for cutting tool in turning based in a toolholder with cooling fluid flowing inside its body being that this fluid must necessarily be able to phase change due to heat generated from machining processes. In this way, the fluid evaporates just under the cutting tool allowing a heat transfer more efficient than if were used a fluid without phase change once the latent heat of evaporation is beneficial for removal heat. Following, the cooling fluid evaporated passes through a condenser located out of the toolholder where it is condensated and returns to the toolholder again and a new cycle is started. In this study, the R-123, a hydrochlorofluorocarbon (HCFC) fluid, was selected for the turning of a Cr-Ni-Nb-Mn-N austenitic steel of hard machinability. The machining tests were carried out under three different machining conditions: dry machining, external cutting fluid (conventional method), and with the toolholder proposed. As result, the developed system allows a surface roughness up to 10% better than dry machining and a tool life close to the conventional method, but 32% superior to dry machining; moreover, there are environmental and economics advantages once the cooling fluid is maintained in a loop circuit.
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Aim To evaluate whether observed geographical shifts in the distribution of the blue-winged macaw (Primolius maracana) are related to ongoing processes of global climate change. This species is vulnerable to extinction and has shown striking range retractions in recent decades, withdrawing broadly from southern portions of its historical distribution. Its range reduction has generally been attributed to the effects of habitat loss; however, as this species has also disappeared from large forested areas, consideration of other factors that may act in concert is merited.Location Historical distribution of the blue-winged macaw in Brazil, eastern Paraguay and northern Argentina.Methods We used a correlative approach to test a hypothesis of causation of observed shifts by reduction of habitable areas mediated by climate change. We developed models of the ecological niche requirements of the blue-winged macaw, based on point-occurrence data and climate scenarios for pre-1950 and post-1950 periods, and tested model predictivity for anticipating geographical distributions within time periods. Then we projected each model to the other time period and compared distributions predicted under both climate scenarios to assess shifts of habitable areas across decades and to evaluate an explanation for observed range retractions.Results Differences between predicted distributions of the blue-winged macaw over the twentieth century were, in general, minor and no change in suitability of landscapes was predicted across large areas of the species' original range in different time periods. No tendency towards range retraction in the south was predicted, rather conditions in the southern part of the species' range tended to show improvement for the species.Main conclusions Our test permitted elimination of climate change as a likely explanation for the observed shifts in the distribution of the blue-winged macaw, and points rather to other causal explanations (e.g. changing regional land use, emerging diseases).
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The deconvolution of the voltammograms of polypyrrole electrochemistry has proved to be possible through the electrochemical quartz crystal microbalance data using the F(dm/dQ) function. This deconvolution allows the evolution of the thickness of the polypyrrole films during their redox processes to be estimated and therefore, the mechanical contraction/decontraction of this polymer as a function of the ionic exchange processes can be evaluated. (c) 2005 Elsevier B.V. All rights reserved.
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Includes bibliography
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Includes bibliography
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Includes bibliography.
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The Caribbean region remains highly vulnerable to the impacts of climate change. In order to assess the social and economic consequences of climate change for the region, the Economic Commission for Latin America and the Caribbean( ECLAC) has developed a model for this purpose. The model is referred to as the Climate Impact Assessment Model (ECLAC-CIAM) and is a tool that can simultaneously assess multiple sectoral climate impacts specific to the Caribbean as a whole and for individual countries. To achieve this goal, an Integrated Assessment Model (IAM) with a Computable General Equilibrium Core was developed comprising of three modules to be executed sequentially. The first of these modules defines the type and magnitude of economic shocks on the basis of a climate change scenario, the second module is a global Computable General Equilibrium model with a special regional and industrial classification and the third module processes the output of the CGE model to get more disaggregated results. The model has the potential to produce several economic estimates but the current default results include percentage change in real national income for individual Caribbean states which provides a simple measure of welfare impacts. With some modifications, the model can also be used to consider the effects of single sectoral shocks such as (Land, Labour, Capital and Tourism) on the percentage change in real national income. Ultimately, the model is envisioned as an evolving tool for assessing the impact of climate change in the Caribbean and as a guide to policy responses with respect to adaptation strategies.