813 resultados para Travel behavior, Time use, Activity modeling, Land use, Urban form, Simultaneous Tobit


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Transport planning necessarily takes into account more than just the immediate time-frame. In the case of urban transport, planning needs to come up with solutions in regard to infrastructure which is expensive and may have a useful life extending over several decades. Therefore, planning must take note of economic, technological, social and demographic changes that influence trips undertaken.The purpose of this article is to explore some of the trends that may well be observed in upcoming decades. The article arrives at the conclusion that, in a period of considerable change and uncertainty, failure to take heed of recent trends may result in the construction of infrastructure that is not always the most appropriate and, what is more, that urban development militates against the efficient operation of public transport and, as a result, is likely to jeopardize the sustainability of cities in the long term.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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The occurrence of a weak auditory warning stimulus increases the speed of the response to a subsequent visual target stimulus that must be identified. This facilitatory effect has been attributed to the temporal expectancy automatically induced by the warning stimulus. It has not been determined whether this results from a modulation of the stimulus identification process, the response selection process or both. The present study examined these possibilities. A group of 12 young adults performed a reaction time location identification task and another group of 12 young adults performed a reaction time shape identification task. A visual target stimulus was presented 1850 to 2350 ms plus a fixed interval (50, 100, 200, 400, 800, or 1600 ms, depending on the block) after the appearance of a fixation point, on its left or right side, above or below a virtual horizontal line passing through it. In half of the trials, a weak auditory warning stimulus (S1) appeared 50, 100, 200, 400, 800, or 1600 ms (according to the block) before the target stimulus (S2). Twelve trials were run for each condition. The S1 produced a facilitatory effect for the 200, 400, 800, and 1600 ms stimulus onset asynchronies (SOA) in the case of the side stimulus-response (S-R) corresponding condition, and for the 100 and 400 ms SOA in the case of the side S-R non-corresponding condition. Since these two conditions differ mainly by their response selection requirements, it is reasonable to conclude that automatic temporal expectancy influences the response selection process.

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Ordinary yet unique, water is the substance on which life is based. Water seems, at first sight, to be a very simple molecule, consisting of two hydrogen atoms attached to one oxygen. Its small size belies the complexity of its action and its numerous anomalies, central to a broad class of important phenomena, ranging from global current circulation, terrestrial water and CO2 cycles to corrosion and wetting. The explanation of this complex behavior comes from water's unique ability to form extensive three-dimensional networks of hydrogen-bonds, whose nature and structures, in spite of a great deal of efforts involving a plethora of experimental and theoretical techniques, still lacks a complete scientific understanding. This thesis is devoted to the study of the local structure of hydrogen-bonded liquids, with a particular emphasis on water, taking advantage of a combination of core-level spectroscopies and density functional theory spectra calculations. X-ray absorption, in particular, is found to be sensitive to the local hydrogen-bond environment, thus offering a very promising tool for spectroscopic identification of specific structural configurations in water, alcohols and aqueous solutions. More specifically, the characteristic spectroscopic signature of the broken hydrogen-bond at the hydrogen side is used to analyze the structure of bulk water, leading to the finding that most molecules are arranged in two hydrogen-bond configurations, in contrast to the picture provided by molecular dynamics simulations. At the liquid-vapor interface, an interplay of surface sensitive measurements and theoretical calculations enables us to distinguish a new interfacial species in equilibrium with the gas. In a similar approach the cluster form of the excess proton in highly concentrated acid solutions and the different coordination of methanol at the vacuum interface and in the bulk can also be clearly identified. Finally the ability of core-level spectroscopies, aided by sophisticated density functional theory calculations, to directly probe the valence electronic structure of a system is used to observe the nature of the interaction between water molecules and solvated ions in solution. Water around transition metal ions is found to interact with the solute via orbital mixing with the metal d-orbitals. The hydrogen-bond between water molecules is explained in terms of electrostatic interactions enhanced by charge rehybridization in which charge transfer between connecting molecules is shown to be fundamental.

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agriculture périurbaine, droit foncier, conflits fonciers, developpement urbain

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Cor-Ten is a particular kind of steel, belonging to low-alloyed steel; thanks to his aesthetic features and resistance to atmospheric corrosion, this material is largely used in architectural, artistic and infrastructural applications. After environmental exposure, Cor-Ten steel exhibits the characteristic ability to self-protect from corrosion, by the development of a stable and adherent protective layer. However, some environmental factors can influence the formation and stability of the patina. In particular, exposure of Cor-Ten to polluted atmosphere (NOx, SOx, O3) or coastal areas (marine spray) may cause problems to the protective layer and, as a consequence, a release of alloying metals, which can accumulate near the structures. Some of these metals, such as Cr and Ni, could be very dangerous for soils and water because of their large toxicity. The aim of this work was to study the corrosion behavior of Cor-Ten exposed to an urban-coastal site (Rimini, Italy). Three different kinds of commercial surface finish (bare and pre-patinated, with or without a beeswax covering) were examined, both in sheltered and unsheltered exposure conditions. Wet deposition brushing the specimens surface (leaching solutions) are monthly collected and analyzed to evaluate the extent of metal release and the form in which they leave the surface, for example, as water-soluble compounds or non-adherent corrosion products. Five alloying metals (Fe, Cu, Cr, Mn and Ni) and nine ions (Cl-, NO3-, NO2-, SO42-, Na+, Ca2+, K+, Mg2+, NH4+) are determined through Atomic Absorption Spectroscopy and Ion Chromatography, respectively. Furthermore, the evolution and the behaviour of the patina are periodically followed by surface investigations (SEM-EDS and Raman Spectroscopy). After two years of exposure, the results show that Bare Cor-Ten, cheaper than the other analyzed specimens, even though undergoes the greater mass variation, his metal release is comparable to the release of the pre-patinated samples. The behavior of pre-patinated steel, with or without beeswax covering, do not show particular difference. This exposure environment doesn’t allow a completely stabilization of the patina; nevertheless an estimate of metal release after 10 years of exposure points out that the environmental impact of Cor-Ten is very low: for example, the release of chromium in the soluble fraction is less than 10 mg if we consider an exposed wall of 10 m2.

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Residential wood combustion has only recently been recognized as a major contributor to air pollution in Switzerland and in other European countries. A source apportionment method using the aethalometer light absorption parameters was applied to five winter campaigns at three sites in Switzerland: a village with high wood combustion activity in winter, an urban background site and a highway site. The particulate mass from traffic (PMtraffic) and wood burning (PMwb) emissions obtained with this model compared fairly well with results from the 14C source apportionment method. PMwb from the model was also compared to well known wood smoke markers such as anhydrosugars (levoglucosan and mannosan) and fine mode potassium, as well as to a marker recently suggested from the Aerodyne aerosol mass spectrometer (mass fragment m/z 60). Additionally the anhydrosugars were compared to the 14C results and were shown to be comparable to literature values from wood burning emission studies using different types of wood (hardwood, softwood). The levoglucosan to PMwb ratios varied much more strongly between the different campaigns (4–13%) compared to mannosan to PMwb with a range of 1–1.5%. Possible uncertainty aspects for the various methods and markers are discussed.

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Phosphatidylinositol 3-kinase (PI3K) generates membrane phospholipids that serve as second messengers to recruit signaling proteins to plasma membrane consequently regulating cell growth and survival. PI3K is a heterodimer consisting of a catalytic p110 subunit and a regulatory p85 subunit. Association of the p85 with other signal proteins is critical for induced PI3K activation. Activated PI3K, in turn, leads to signal flows through a variety of PI3K effectors including PDK1, AKT, GSK3, BAD, p70 S6K and NFκB. The PI3K pathway is under regulation by multiple signal proteins representing cross-talk between different signaling cascades. In this study, we have evaluated the role of protein kinase C family kinases on signaling through PI3K at multiple levels. Firstly, we observed that the action of PKC specific inhibitors like Ro-31-8220 and GF109203X was associated with an increased AKT phosphorylation and activity, suggesting that PKC kinases might play a negative role in the regulation of PI3K pathway. Then, we demonstrated the stimulation of AKT by PKC inhibition was dependent on functional PI3K enzyme and able to be transmitted to the AKT effector p70 S6K. Furthermore, we showed an inducible physical association between the PKCζ isotype and AKT, which was accompanied by an attenuated AKT activity. However, a kinase-dead form of PKC failed to affect AKT. In the second part of our research we revealed the ability of a different PKC family member, PKCδ to bind to the p85 subunit of PI3K in response to oxidative stress, a process requiring the activity of src tyrosine kinases. The interaction was demonstrated to be a direct and specific contact between the carboxyl terminal SH2 domain of p85 and tyrosine phosphorylated PKCδ. Several different types of agonists were capable to induce this association including tyrosine kinases and phorbol esters with PKCδ tyrosine phosphorylation being integral components. Finally, the PKCδ-PI3K complex was related to a reduction in the AKT phosphorylation induced by src. A kinase-deficient mutant of PKCδ was equally able to inhibit AKT signal as the wild type, indicative of a process independent of PKCδ catalytic activity. Altogether, our data illustrate different PKC isoforms regulating PI3K pathway at multiple levels, suggesting a mechanism to control signal flows through PI3K for normal cell activities. Although further investigation is required for full understanding of the regulatory mechanism, we propose that complex formation of signal proteins in PI3K pathway and specific PKC isoforms plays important role in their functional linkage. ^

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It is shown that in 2002-2005 mass development of coccolithofore Emiliania huxleyi on the Gelendzhik shelf (northeast Black Sea) occurred annually and in May-June its abundance reached 1500000 cells/l. In 2004-2005 bloom of E. huxleyi was accompanied by mass development of diatom alga Chaetoceros subtilis var. abnormis f. simplex (600000-900000 cells/l). For the first time it was registered as a dominating form of Black Sea phytoplankton. Small flagellates and picoplankton algae played a noticeable role in phytoplankton throughout the entire period of the studies. Meanwhile in the early summer period the bulk of biomass consisted of coccolithophores (50-60%), while in the late summer period diatomaceous algae dominated (50-70%). Among ecological factors that favor coccolithophore development one may note microstratification of the upper mixed layer at a high illumination level and high temperature in surface waters (18-21°C). Terrigenous runoff during the rainy period had a negative effect on E. huxleyi development, while storms dispersed the population over the upper mixed layer. A wind-induced near-shore upwelling stimulated development of diatoms.

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El propósito principal de éste trabajo tiene que ver con los procesos de modelado del espacio social, utilizando como campo de estudio los efectos sobre la morfología urbana generados por la implantación del sistema de transporte Masivo Transbarca en la ciudad venezolana de Barquisimeto. La investigación se apoya en buena medida en las teorías de la morfología social elaboradas por el sociólogo E. Durkheim y desarrolladas sobre todo en el campo del urbanismo por M. Halbwachs. En ellas se vincula la morfología social con su sustrato material, la forma urbana, desde una perspectiva sociológica. De igual manera se consideran categorías conceptuales como fragmentación y segregación, según otros enfoques (M. Castells y Reales). El trabajo se desarrolla según una metodología empírica, realizando análisis cuantitativos de los fenómenos que se consideran indicativos (el mercado de vivienda, por ejemplo) y comprobando su relación con la cualificación del espacio urbano donde destacan los procesos de remodelación de la centralidad que resultan de la implantación del Transporte Masivo. Desde esta perspectiva, la solución al transporte colectivo adquiere una dimensión que trasciende su papel como pieza fundamental para el buen funcionamiento de la ciudad moderna en crecimiento, con independencia de que sea capaz de ofrecer una solución a ese desafío, para convertirse en un instrumento de ordenación de la ciudad que afecta a la morfología social y urbana, que supone profundas alteraciones del centro urbano propiamente dicho, que implica una redistribución de los grupos sociales en el espacio reformado de la ciudad: un proceso de remodelación y transformación del espacio funcional y social, presentado como una solución a los problemas de movilidad. También en Venezuela, como en otras partes, la evolución de la morfología social está relacionada con profundos cambios ocurridos en los sustratos físico-estructurales de las ciudades, que a su vez se vinculan con la dinámica de los procesos de globalización que nutren la dinámica interna de construcción y reconstrucción de esos espacios. SUMMARY The main purpose of this work deals with modeling processes of social space, using as a field of study the effects on urban morphology generated by the implementation of the transport system Transbarca Mass in the Venezuelan city of Barquisimeto. The research was based largely on theories of social morphology developed by sociologist E. Durkheim and developed primarily in the field of urban M. Halbwachs. They linked the social morphology with its substrate material, urban form, from a sociological perspective. Similarly conceptual categories are considered as fragmentation and segregation, as other approaches (M. Castells and Royals). The work is developed as an empirical methodology, performing quantitative analysis of the phenomena that are considered indicative (the housing market, for example) and checking its relation to the qualification of urban space which include remodeling processes resulting from the centrality the implementation of mass transportation. From this perspective, collective transport solution acquires a dimension that transcends its role as a cornerstone for the functioning of the modern city growing, regardless of who is able to offer a solution to this challenge, to become an instrument of City management affecting the social and urban morphology, reflecting profound alterations in the city center itself, which implies a redistribution of social groups in the city renovated space: a process of renovation and transformation of social and functional space presented as a solution to mobility problems. Also in Venezuela, as elsewhere, the development of social morphology is associated with profound changes in the physical and structural substrates of cities, which in turn are linked to the dynamics of globalization processes that nourish the internal dynamics construction and reconstruction of these areas.

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Understanding the location patterns of firms within a region has proved to be an important factor to study the development of urban form. Moreover, the study of firms location patterns allows the implementation of the adequate policy strategies to increase firms location rate in certain areas, for example when practitioners are dealing with deprived zones. The aim of this paper is to map firmographic data as a function of its location over a certain period of time, and its employment weight in order to discuss which factors have a direct impact on the results and to highlight which specific areas need the adequate measures to promote employment and public transportation. As a case study, it is proposed to analyze the southwest region of Madrid. Spatial statistic methods were used for this study, which were found to be very efficient in order to evaluate which areas need special attention.

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La tesis doctoral titulada “El Poblado Dirigido de Caño Roto. Dialéctica entre morfología urbana y tipología edificatoria” analiza el poblado de Caño Roto, un vecindario de vivienda social construido en Madrid entre 1957 y 1963, a partir de la relación entre la edificación y la forma urbana resultante. También, la investigación desarrolla un análisis historiográfico de la obra así como de las condiciones políticas, sociales, económicas y normativas existentes en el momento de su realización, para concluir con un estudio comparativo entre éste y otros proyectos análogos al poblado en aspectos como el marco temporal y geopolítico, los planteamientos urbanísticos y algunas soluciones tipológicas y constructivas. El trabajo pretende, por un lado, profundizar en el conocimiento que se tiene actualmente de esta obra, considerada por muchos como una de las más relevantes de la arquitectura española contemporánea, y, por otro, extraer a partir de su estudio, pautas, criterios y estrategias de diseño urbano que puedan ser extrapolables al proyecto contemporáneo; a fin de superar los actuales, pero obsoletos, modelos de desarrollo. No obstante, sabemos que cualquier respuesta que plantee una vuelta al pasado está condenada al fracaso. Las circunstancias cambian y, en consecuencia, las soluciones no pueden ser las mismas. Pero si las respuestas ya no nos sirven, las preguntas siguen siendo válidas. Quién es el protagonista del diseño urbano en Caño Roto. Cómo conviven el tráfico peatonal y el rodado. Cuál es la densidad del barrio. Cómo se articulan los usos residencial, comercial y dotacional. De qué manera se organiza el tejido urbano. Qué relación existe entre los tipos edificatorios y la morfología urbana resultante; y entre los espacios de uso privado o restringido y los de uso público. Partimos de la hipótesis de que los análisis, reflexiones y resultados derivados de interrogar al poblado de Caño Roto acerca de estas, y otras muchas, cuestiones nos permitirán alcanzar un entendimiento global de la complejidad urbana y nos revelarán, además, propuestas y soluciones que contribuyan a mejorar la calidad de nuestras ciudades; ahora y en adelante. ABSTRACT The thesis entitled “El Poblado Dirigido de Caño Roto. Dialéctica entre morfología urbana y tipología edificatoria” [Poblado Dirigido of Caño Roto. Dialectic between urban morphology and typology] analyzes Caño Roto, a social housing neighborhood built in Madrid between 1957 and 1963, from the relationship between buildings and the resulting urban form. Also, this research develops a historiographical analysis of this project as well as the social, political, financial and legislative conditions present at time of its construction. This thesis concludes with a comparative study with other similar projects in temporal and geopolitical framework, urban approaches and some typological and constructive solutions. The research aims, on the one hand, to expand the current knowledge about Caño Roto, considered by many as one of the most important project at Spanish contemporary architecture; and, on the other hand, deducing from the study guidelines, criteria and strategies of urban design which can be extrapolated to contemporary architecture and urbanism. This way, we will be able to overcome current, but obsolete development models. However, we know that any response that suggests coming back to the past is destined to failure. Circumstances change and, consequently, solutions cannot be the same. But if the answers do not serve, questions are still right. Who is the protagonist of Caño Roto urban design? How do pedestrian and road traffic coexist together? What is the neighborhood’s density? How are residential, commercial and endowment uses articulated? How is urban fabric organized? What is the relationship between building types and the resulting urban morphology; and between private and public spaces? We start from the hypothesis that analysis, reflections and results arising from questioning Caño Roto about these, and many others, issues will enable us to have a comprehensive understanding of urban complexity, and they will also reveal proposals and solutions which help us to improve the quality of our cities; from now on.

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The brain can hold the eyes still because it stores a memory of eye position. The brain’s memory of horizontal eye position appears to be represented by persistent neural activity in a network known as the neural integrator, which is localized in the brainstem and cerebellum. Existing experimental data are reinterpreted as evidence for an “attractor hypothesis” that the persistent patterns of activity observed in this network form an attractive line of fixed points in its state space. Line attractor dynamics can be produced in linear or nonlinear neural networks by learning mechanisms that precisely tune positive feedback.