921 resultados para Bottom-up processes


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Recent empirical studies about the neurological executive nature of reading in bilinguals differ in their evaluations of the degree of selective manifestation in lexical access as implicated by data from early and late reading measures in the eye-tracking paradigm. Currently two scenarios are plausible: (1) Lexical access in reading is fundamentally language non-selective and top-down effects from semantic context can influence the degree of selectivity in lexical access; (2) Cross-lingual lexical activation is actuated via bottom-up processes without being affected by top-down effects from sentence context. In an attempt to test these hypotheses empirically, this study analyzed reader-text events arising when cognate facilitation and semantic constraint interact in a 22 factorially designed experiment tracking the eye movements of 26 Swedish-English bilinguals reading in their L2. Stimulus conditions consisted of high- and low-constraint sentences embedded with either a cognate or a non-cognate control word. The results showed clear signs of cognate facilitation in both early and late reading measures and in either sentence conditions. This evidence in favour of the non-selective hypothesis indicates that the manifestation of non-selective lexical access in reading is not constrained by top-down effects from semantic context.

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Benthic marine invertebrates may form metapopulations connected via propagule dispersal. Conservation efforts often target potential source coastlines to indirectly benefit areas depending on allochthonous offspring production. Besides population density, adult size structure, sex ratio, brooding frequency and the proportion of breeding individuals may significantly influence the reproductive output of benthic populations, but these effects have seldom been tested. We used rocky shore crabs to assess the spatial variability of such parameters at relevant scales for conservation purposes and to test their consistency over 2 consecutive years; we then used the data to address whether bottom-up processes or biological interactions might explain the patterns observed. We decomposed egg production rates into their components for the 2 most abundant brachyuran species inhabiting the intertidal rocky habitat. Adult density and brooding frequency varied consistently among shores for both species and largely explained the overall spatial trends of egg production. Temporally consistent patterns also included among-shore differences in the size of ovigerous females of the grapsid Pachygrapsus transversus and between-bay differences in the fecundity of the spider crab Epialtus brasiliensis. Sex ratio was remarkably constant in both. We found no positive or negative correlations between adult density and brooding frequency to support either the existence of a component Allee effect (lack of mate encounters) or an effect of intra-specific competition. Likewise, shore-specific potential growth in P. transversus does not negatively correlate with frequency of ovigerous individuals, as would be expected under a critical balance between these 2 processes. The patterns observed suggest that bottom-up drivers may best explain spatial trends in the reproductive output of these species.

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Sedentary consumers play an important role on populations of prey and, hence, their patterns of abundance, distribution and coexistence on shores are important to evaluate their potential influence on ecosystem dynamics. Here, we aimed to describe their spatio-temporal distribution and abundance in relation to wave exposure in the intertidal rocky shores of the south-west Atlantic to provide a basis for further understanding of ecological processes in this system. The abundance and composition of the functional groups of sessile organisms and sedentary consumers were taken by sampling the intertidal of sheltered and moderately exposed shores during a period of one year. The sublittoral fringe of sheltered areas was dominated by macroalgae, while the low midlittoral was dominated by bare rock and barnacles. In contrast, filter-feeding animals prevailed at exposed shores, probably explaining the higher abundance of the predator Stramonita haemastoma at these locations. Limpets were more abundant at the midlittoral zone of all shores while sea urchins were exclusively found at the sublittoral fringe of moderately exposed shores, therefore, adding grazing pressure on these areas. The results showed patterns of coexistence, distribution and abundance of those organisms in this subtropical area, presumably as a result of wave action, competition and prey availability. It also brought insights on the influence of top-down and bottom-up processes in this area.

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This is a draft for a chapter of the book version of my Ph.D thesis. The chapter addresses the following question: Are the creative processes of musical composers and academic economists essentially the same, or are there significant differences? The paper finds that there are deep similarities between the creative processes of theoretical economists and the creative processes of artists. The chapter builds a process oriented lifecycle account of creative activity, drawing on testimonial material from the arts and the sciences, and relates the model to the creative work of economists developing economic theory.

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When speech is degraded, word report is higher for semantically coherent sentences (e.g., her new skirt was made of denim) than for anomalous sentences (e.g., her good slope was done in carrot). Such increased intelligibility is often described as resulting from "top-down" processes, reflecting an assumption that higher-level (semantic) neural processes support lower-level (perceptual) mechanisms. We used time-resolved sparse fMRI to test for top-down neural mechanisms, measuring activity while participants heard coherent and anomalous sentences presented in speech envelope/spectrum noise at varying signal-to-noise ratios (SNR). The timing of BOLD responses to more intelligible speech provides evidence of hierarchical organization, with earlier responses in peri-auditory regions of the posterior superior temporal gyrus than in more distant temporal and frontal regions. Despite Sentence content × SNR interactions in the superior temporal gyrus, prefrontal regions respond after auditory/perceptual regions. Although we cannot rule out top-down effects, this pattern is more compatible with a purely feedforward or bottom-up account, in which the results of lower-level perceptual processing are passed to inferior frontal regions. Behavioral and neural evidence that sentence content influences perception of degraded speech does not necessarily imply "top-down" neural processes.

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The developmental processes and functions of an organism are controlled by the genes and the proteins that are derived from these genes. The identification of key genes and the reconstruction of gene networks can provide a model to help us understand the regulatory mechanisms for the initiation and progression of biological processes or functional abnormalities (e.g. diseases) in living organisms. In this dissertation, I have developed statistical methods to identify the genes and transcription factors (TFs) involved in biological processes, constructed their regulatory networks, and also evaluated some existing association methods to find robust methods for coexpression analyses. Two kinds of data sets were used for this work: genotype data and gene expression microarray data. On the basis of these data sets, this dissertation has two major parts, together forming six chapters. The first part deals with developing association methods for rare variants using genotype data (chapter 4 and 5). The second part deals with developing and/or evaluating statistical methods to identify genes and TFs involved in biological processes, and construction of their regulatory networks using gene expression data (chapter 2, 3, and 6). For the first part, I have developed two methods to find the groupwise association of rare variants with given diseases or traits. The first method is based on kernel machine learning and can be applied to both quantitative as well as qualitative traits. Simulation results showed that the proposed method has improved power over the existing weighted sum method (WS) in most settings. The second method uses multiple phenotypes to select a few top significant genes. It then finds the association of each gene with each phenotype while controlling the population stratification by adjusting the data for ancestry using principal components. This method was applied to GAW 17 data and was able to find several disease risk genes. For the second part, I have worked on three problems. First problem involved evaluation of eight gene association methods. A very comprehensive comparison of these methods with further analysis clearly demonstrates the distinct and common performance of these eight gene association methods. For the second problem, an algorithm named the bottom-up graphical Gaussian model was developed to identify the TFs that regulate pathway genes and reconstruct their hierarchical regulatory networks. This algorithm has produced very significant results and it is the first report to produce such hierarchical networks for these pathways. The third problem dealt with developing another algorithm called the top-down graphical Gaussian model that identifies the network governed by a specific TF. The network produced by the algorithm is proven to be of very high accuracy.

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Effective strategies for recruiting volunteers who are prepared to make a long-term commitment to formal positions are essential for the survival of voluntary sport clubs. This article examines the decision-making processes in relation to these efforts. Under the assumption of bounded rationality, the garbage can model is used to grasp these decision-making processes theoretically and access them empirically. Based on case study framework an in-depth analysis of recruitment practices was conducted in nine selected sport clubs. Results showed that the decision-making processes are generally characterized by a reactive approach in which dominant actors try to handle personnel problems of recruitment in the administration and sport domains through routine formal committee work and informal networks. In addition, it proved possible to develop a typology that deliver an overview of different decision-making practices in terms of the specific interplay of the relevant components of process control (top-down vs. bottom-up) and problem processing (situational vs. systematic).

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This article presents constitutionality as a new approach for analyzing bottom-up institution-building processes emphasizing local perceptions and local agency in common pool resource management. Using four case studies—fisheries in Zambia; pasture and forestry in Mali; fisheries in Indonesia; forestry in Bolivia—this approach analyzes examples of local institution building differing from top-down imposed participation. Our analysis highlights six components of constitutionality: emic perceptions of the need for new institutions, participatory processes of negotiation, preexisting institutions as a basis for institution building, outside catalyzing agents, recognition of local knowledge, and higher level acknowledgment of the new institutions.

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This chapter aims to overcome the gap existing between case study research, which typically provides qualitative and process-based insights, and national or global inventories that typically offer spatially explicit and quantitative analysis of broader patterns, and thus to present adequate evidence for policymaking regarding large-scale land acquisitions. Therefore, the chapter links spatial patterns of land acquisitions to underlying implementation processes of land allocation. Methodologically linking the described patterns and processes proved difficult, but we have identified indicators that could be added to inventories and monitoring systems to make linkage possible. Combining complementary approaches in this way may help to determine where policy space exists for more sustainable governance of land acquisitions, both geographically and with regard to processes of agrarian transitions. Our spatial analysis revealed two general patterns: (i) relatively large forestry-related acquisitions that target forested landscapes and often interfere with semi-subsistence farming systems; and (ii) smaller agriculture-related acquisitions that often target existing cropland and also interfere with semi-subsistence systems. Furthermore, our meta-analysis of land acquisition implementation processes shows that authoritarian, top-down processes dominate. Initially, the demands of powerful regional and domestic investors tend to override socio-ecological variables, local actors’ interests, and land governance mechanisms. As available land grows scarce, however, and local actors gain experience dealing with land acquisitions, it appears that land investments begin to fail or give way to more inclusive, bottom-up investment models.

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En las últimas tres décadas, las dinámicas de restructuración económica a nivel global han redefinido radicalmente el papel de las ciudades. La transición del keynesianismo al neoliberalismo ha provocado un cambio en las políticas urbanas de los gobiernos municipales, que han abandonado progresivamente las tareas de regulación y redistribución para centrarse en la promoción del crecimiento económico y la competitividad. En este contexto, muchas voces críticas han señalado que la regeneración urbana se ha convertido en un vehículo de extracción de valor de la ciudad y está provocando la expulsión de los ciudadanos más vulnerables. Sin embargo, la regeneración de áreas consolidadas supone también una oportunidad de mejora de las condiciones de vida de la población residente, y es una política necesaria para controlar la expansión de la ciudad y reducir las necesidades de desplazamiento, promoviendo así ciudades más sostenibles. Partiendo de la hipótesis de que la gobernanza de los procesos de regeneración urbana es clave en el resultado final de las operaciones y determina el modelo de ciudad resultante, el objetivo de esta investigación es verificar si la regeneración urbana es necesariamente un mecanismo de extracción de valor o si puede mejorar la calidad de vida en las ciudades a través de la participación de los ciudadanos. Para ello, propone un marco de análisis del proceso de toma de decisiones en los planes de regeneración urbana y su impacto en los resultados de los planes, tomando como caso de estudio la ciudad de Boston, que desde los años 1990 trata de convertirse en una “ciudad de los barrios”, fomentando la participación ciudadana al tiempo que se posiciona en la escena económica global. El análisis se centra en dos operaciones de regeneración iniciadas a finales de los años 1990. Por un lado, el caso de Jackson Square nos permite comprender el papel de la sociedad civil y el tercer sector en la regeneración de los barrios más desfavorecidos, en un claro ejemplo de urbanismo “desde abajo” (bottom-up planning). Por otro, la reconversión del frente marítimo de South Boston para la construcción del Distrito de Innovación nos acerca a las grandes operaciones de regeneración urbana con fines de estímulo económico, tradicionalmente vinculadas a los centros financieros (downtown) y dirigidas por las élites gubernamentales y económicas (la growth machine) a través de procesos más tecnocráticos (top-down planning). La metodología utilizada consiste en el análisis cualitativo de los procesos de toma de decisiones y la relación entre los agentes implicados, así como de la evaluación de la implementación de dichas decisiones y su influencia en el modelo urbano resultante. El análisis de los casos permite afirmar que la gobernanza de los procesos de regeneración urbana influye decisivamente en el resultado final de las intervenciones; sin embargo, la participación de la comunidad local en la toma de decisiones no es suficiente para que el resultado de la regeneración urbana contrarreste los efectos de la neoliberalización, especialmente si se limita a la fase de planeamiento y no se extiende a la fase de ejecución, y si no está apoyada por una movilización política de mayor alcance que asegure una acción pública redistributiva. Asimismo, puede afirmarse que los procesos de regeneración urbana suponen una redefinición del modelo de ciudad, dado que la elección de los espacios de intervención tiene consecuencias sobre el equilibrio territorial de la ciudad. Los resultados de esta investigación tienen implicaciones para la disciplina del planeamiento urbano. Por una parte, se confirma la vigencia del paradigma del “urbanismo negociado”, si bien bajo discursos de liderazgo público y sin apelación al protagonismo del sector privado. Por otra parte, la planificación colaborativa en un contexto de “responsabilización” de las organizaciones comunitarias puede desactivar la potencia política de la participación ciudadana y servir como “amortiguador” hacia el gobierno local. Asimismo, la sustitución del planeamiento general como instrumento de definición de la ciudad futura por una planificación oportunista basada en la actuación en áreas estratégicas que tiren del resto de la ciudad, no permite definir un modelo coherente y consensuado de la ciudad que se desea colectivamente, ni permite utilizar el planeamiento como mecanismo de redistribución. ABSTRACT In the past three decades, the dynamics of global economic restructuring have radically redefined the role of cities. The transition from keynesianism to neoliberalism has caused a shift in local governments’ urban policies, which have progressively abandoned the tasks of regulation and redistribution to focus on promoting economic growth and competitiveness. In this context, many critics have pointed out that urban regeneration has become a vehicle for extracting value from the city and is causing the expulsion of the most vulnerable citizens. However, regeneration of consolidated areas is also an opportunity to improve the living conditions of the resident population, and is a necessary policy to control the expansion of the city and reduce the need for transportation, thus promoting more sustainable cities. Assuming that the governance of urban regeneration processes is key to the final outcome of the plans and determines the resulting city model, the goal of this research is to verify whether urban regeneration is necessarily a value extraction mechanism or if it can improve the quality of life in cities through citizens’ participation. It proposes a framework for analysis of decision-making in urban regeneration processes and their impact on the results of the plans, taking as a case study the city of Boston, which since the 1990s is trying to become a "city of neighborhoods", encouraging citizen participation, while seeking to position itself in the global economic scene. The analysis focuses on two redevelopment plans initiated in the late 1990s. The Jackson Square case allows us to understand the role of civil society and the third sector in the regeneration of disadvantaged neighborhoods, in a clear example of bottom-up planning. On the contrary, the conversion of the South Boston waterfront to build the Innovation District takes us to the big redevelopment efforts with economic stimulus’ goals, traditionally linked to downtowns and led by government and economic elites (the local “growth machine”) through more technocratic processes (top-down planning). The research is based on a qualitative analysis of the processes of decision making and the relationship between those involved, as well as the evaluation of the implementation of those decisions and their influence on the resulting urban model. The analysis suggests that the governance of urban regeneration processes decisively influences the outcome of interventions; however, community engagement in the decision-making process is not enough for the result of the urban regeneration to counteract the effects of neoliberalization, especially if it is limited to the planning phase and does not extend to the implementation of the projects, and if it is not supported by a broader political mobilization to ensure a redistributive public action. Moreover, urban regeneration processes redefine the urban model, since the choice of intervention areas has important consequences for the territorial balance of the city. The results of this study have implications for the discipline of urban planning. On the one hand, it confirms the validity of the "negotiated planning" paradigm, albeit under public leadership discourse and without a direct appeal to the leadership role of the private sector. On the other hand, collaborative planning in a context of "responsibilization" of community based organizations can deactivate the political power of citizen participation and serve as a "buffer" towards the local government. Furthermore, the replacement of comprehensive planning, as a tool for defining the city's future, by an opportunistic planning based on intervention in strategic areas that are supposed to induce change in the rest of the city, does not allow a coherent and consensual urban model that is collectively desired, nor it allows to use planning as a redistribution mechanism.

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2000 Mathematics Subject Classification: 60K15, 60K20, 60G20,60J75, 60J80, 60J85, 60-08, 90B15.

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Dissertação apresentada para obtenção do Grau de Doutor em Engenharia do Ambiente pela Universidade Nova de Lisboa,Faculdade de Ciências e Tecnologia

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Tese de Doutoramento em Ciências da Educação (Área de Conhecimento: Educação ambiental e para a Sustentabilidade)

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Normal visual perception requires differentiating foreground from background objects. Differences in physical attributes sometimes determine this relationship. Often such differences must instead be inferred, as when two objects or their parts have the same luminance. Modal completion refers to such perceptual "filling-in" of object borders that are accompanied by concurrent brightness enhancement, in turn termed illusory contours (ICs). Amodal completion is filling-in without concurrent brightness enhancement. Presently there are controversies regarding whether both completion processes use a common neural mechanism and whether perceptual filling-in is a bottom-up, feedforward process initiating at the lowest levels of the cortical visual pathway or commences at higher-tier regions. We previously examined modal completion (Murray et al., 2002) and provided evidence that the earliest modal IC sensitivity occurs within higher-tier object recognition areas of the lateral occipital complex (LOC). We further proposed that previous observations of IC sensitivity in lower-tier regions likely reflect feedback modulation from the LOC. The present study tested these proposals, examining the commonality between modal and amodal completion mechanisms with high-density electrical mapping, spatiotemporal topographic analyses, and the local autoregressive average distributed linear inverse source estimation. A common initial mechanism for both types of completion processes (140 msec) that manifested as a modulation in response strength within higher-tier visual areas, including the LOC and parietal structures, is demonstrated, whereas differential mechanisms were evident only at a subsequent time period (240 msec), with amodal completion relying on continued strong responses in these structures.