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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
131

Écologie fonctionnelle dans les nappes phréatiques : liens entre flux de matière organique, activité et diversité biologiques / Functional ecology in groundwater : linking organic matter flux and biological activity and diversity

Foulquier, Arnaud 22 September 2009 (has links)
Les réseaux trophiques jouent un rôle primordial dans la régulation des flux de matière et d’énergie au sein des écosystèmes. Dans le cadre des pratiques de recharge artificielle des aquifères, les biocénoses souterraines sont pleinement sollicitées et leur capacité à dégrader les flux de matière organique de surface conditionne le maintien de la qualité des eaux souterraines. L’objectif de ce travail est de déterminer l’influence d’une augmentation des flux de carbone organique dissous sur l’intensité des interactions trophiques entre les communautés microbiennes et les assemblages d’invertébrés au toit des nappes phréatiques rechargées artificiellement avec des eaux de ruissellement pluvial. A travers une approche expérimentale de terrain et de laboratoire, ce travail permet d’évaluer l’intensité des relations existant entre les flux de carbone organique dissous, les conditions environnementales, l’activité et la diversité de communautés microbiennes et l’abondance des communautés d’invertébrés. / Food webs play a crucial role in regulating the fluxes of matter and energy within ecosystems. Artificial recharge of aquifers relies heavily on the ability of groundwater biocenoses to degrade organic matter fluxes that is a condition to maintain the quality of groundwater. The objective of this work is to determine the impact of increased dissolved organic carbon supply on the trophic interactions between the microbial communities and invertebrate assemblages at the upper layers of groundwater artificially recharged with stormwater. Through a combined field and laboratory experimental approach, this work allows ranking the strength of relationship between dissolved organic carbon fluxes, environmental conditions, activity and diversity of microbial communities and abundance of invertebrate assemblages
132

Consumo energético nos setores industriais brasileiros: uma avaliação de desempenho e estratégias para a redução da emissão de CO2 / Energy consumption in the industrial sectors in Brazil: an evaluation of performance and strategies to reduce CO2 emissions

Camioto, Flávia de Castro 04 October 2013 (has links)
Em um período de mudanças climáticas e restrições a emissões cada vez maiores, é importante focar o desenvolvimento das nações na direção de uma economia de baixo carbono. O elevado consumo de combustíveis fósseis gera danos que atingem escalas globais, regionais e locais e põem em risco o suprimento de longo prazo no planeta. O presente trabalho tem como objetivo analisar o desempenho dos principais setores industriais brasileiros considerando seus respectivos consumos energéticos e contribuições para aspectos sociais e econômicos do país. Além disso, busca-se mensurar os benefícios ambientais, no que diz respeito à emissão de CO2, resultante da alteração de energéticos nos setores industriais de menor desempenho e discutir políticas públicas que visam estimular a utilização de fontes de energia mais limpas. Para atingir o objetivo proposto, foi realizada a análise e quantificação da potencial contribuição ambiental que a alteração da matriz energética dos setores com menor desempenho em relação à sua contribuição para o desenvolvimento sustentável, pode fornecer. Para determinar o desempenho dos setores foi utilizada a Análise Envoltória de Dados (DEA). Os resultados deste estudo indicaram que o setor metalúrgico e o setor de não metálicos são os que possuem o menor desempenho, considerando as variáveis selecionadas. Já para medir as emissões de CO2 dos principais combustíveis utilizados nos setores de menor desempenho foi utilizado o método Top-Down proposto pelo IPCC. A análise indicou que, apesar do carvão vegetal ser o segundo emissor de CO2, ele pode contribuir para a redução do aquecimento global, desde que seja proveniente de mata de reflorestamento destinada para a atividade industrial. Por fim, foi realizada uma breve discussão sobre as políticas públicas voltadas a este energético. / In a period of climate change and of an increasingly restriction of emissions, it is pivotal to focus on a development by countries towards an economy revolved on low carbon dioxide levels. The high consumption of fossil fuels results in damages on a global, regional and local level threatening long-term supply in our planet. This work has as its objective to analyze the performance of the main Brazilian industrial sectors considering their energy consumption and contributions to social and economic aspects of the country. In addition, will be measure the environmental benefits, in terms of CO2 emissions, resulting from fuel substitution in the industrial sectors of lower performance and discuss public policies aimed at stimulating the use of cleaner energy sources. So as to achieve this objective, an analysis and measurement assertion of the potential environmental contribution that a change of the energy matrix, of the sectors with lower performance as regards to its contribution to sustainable development of the country, may provide was performed. Data Envelopment Analysis (DEA) was used to determine the efficiency of the sectors. The results of this study indicated that the metallurgical and nonmetallic sectors are the ones that have the lowest performance industrial in terms of sustainable. For the measurement of CO2 emissions for each major fuel used in the sectors with lower performance, the Top-Down method proposed by the IPCC was used. This analysis indicated that, although charcoal is the second fuel in sectors that emit more CO2, it can contribute to the reduction of global warming since it comes from forest reforestation destined for the activity industrial. Finally, a brief discussion about public policies on this fuel was held.
133

Top-down Verarbeitung und neuronale Synchronisation

Siegel, Markus 24 March 2005 (has links)
Wahrnehmung ist kein vollständig durch sensorische Reize determinierter bottom-up Prozeß, sondern wird stark beeinflußt durch von diesen Reizen unabhängige top-down Prozesse wie etwa Aufmerksamkeit oder Erwartungen. Welche neuronalen Mechanismen liegen der Integration von bottom-up und top-down gerichteter Verarbeitung sensorischer Information zu Grunde? Im ersten Teil dieser Arbeit wurde diese Frage an Hand von Simulationen eines neuronales Netzwerks zweier vereinfachter kortikaler Areale untersucht. Dieses Netzwerk berücksichtigt hierbei jüngste zellphysiologische Befunde über die stark asymmetrischen funktionellen Eigenschaften kortikaler Neurone. Das simulierte Netzwerk repliziert zentrale neurophysiologische Befunde: 1) Top-down Signale erhöhen die Feuerraten der Neurone sowohl in einem hierarchisch hohen als auch tiefen kortikalen Areal. 2) Durch selektive top-down Signale wird die Verarbeitung simultaner Reize zu Gunsten eines faszilitierten Reizes moduliert. 3) Durch die reziproke Netzwerkarchitektur kommt es zu einem bidirektionalen Informationsfluß zwischen Arealen. Diese kooperative Verarbeitung bedingt gemeinsam mit einer nichtlinearen somato-dendritischen Interaktion neuronale Salvenentladungen, die ein hohes Signal-Rausch-Verhältnis aufweisen. Das simulierte Netzwerk demonstriert, welche zentrale Rolle die komplexen nichtlinearen Eigenschaften kortikaler Neurone bei der Integration bottom-up und top-down gerichteter Verarbeitung sensorischer Information spielen. Im Mittelpunkt der im zweiten Abschnitt vorgestellten experimentellen Studie steht die hochfrequente Synchronisation neuronaler Aktivität. Das große neurowissenschaftliche Interesse an der zeitlichen Struktur neuronaler Aktivität liegt insbesondere in der kontrovers diskutierten Hypothese eines „Synchronisationscodes“ begründet, gemäß welcher Information nicht nur durch die Feuerraten kortikaler Neurone, sondern auch durch die Synchronisation der Aktionspotentiale einer Neuronenpopulation codiert wird. Finden sich solche Synchronisationsphänomene in wachen, sich unter möglichst natürlichen Bedingungen verhaltenden Tieren wieder? Sind diese Synchronisationen selektiv für Eigenschaften des Reizes? Gelingt es, an Hand eines objektiven Kriteriums ein funktionelles Frequenzband neuronaler Synchronisation zu definieren? Diese Fragestellungen wurden mittels chronischer extrazellulärer Ableitungen im primären visuellen Kortex wacher, sich verhaltender Katzen untersucht: 1) Visuelle Stimulation induziert einen breitbandigen hochfrequenten Anstieg neuronaler Synchronisation. 2) Diese Synchronisation ist selektiv für die Orientierung visueller Reize. 3) Durch Analyse dieser Stimulusselektivität kann ein funktionelles Band neuronaler Synchronisation von etwa 45 Hz bis 120 Hz definiert werden. Diese Untersuchungen an wachen, sich unter vergleichsweise natürlichen Bedingungen verhaltenden Tieren demonstrieren eine überraschend breite Frequenzverteilung neuronaler Synchronisation, die im hochfrequenten Bereich weit über die üblicherweise untersuchten Frequenzbänder hinausreicht. Diese Befunde sprechen gegen die Hypothese hochfrequenter kortikaler Synchronisation als einem schmalbandigen statischen Phänomen. / Sensory perception is not purely a bottom-up process determined only by sensory stimuli, but is strongly dependent on top-down factors such as attention or expectations.Which neuronal mechanisms underlie the integration of bottom-up and top-down directed processing of sensory information? In the first part of this study this question was addressed by numerical simulations of a neural network model of two simplified cortical areas. The simulated network takes into account recent findings concerning the pronounced functional asymmetry of cortical neurons.The network replicates several important neurophysiological findings: 1) Top-down signals enhance firing rates in hierarchically high and low cortical areas. 2) The processing of two competing stimuli is biased towards one stimulus by selective top-down signals. 3) The reciprocal network architecture results in a bidirectional flow of information. Together with the implemented non-linear somato-dendritic interaction this leads to neuronal bursting behaviour with a high signal to noise ratio. The simulated network demonstrates the critical role of the complex non-linear properties of cortical neurons for the integration of bottom-up and top-down directed sensory processing. The central question of the second part of this study is the functional role of high-frequency synchronization of neuronal activity. The strong interest in the temporal dynamics of neuronal activity is particularly due to the hypothesis of a “synchronization-code” according to which information is not solely encoded by firing rates but also by the synchronization of neuronal ensembles. Is such synchronization observed in awake animals behaving under natural conditions? Are these synchronizations stimulus selective? Is it possible to define a functional frequency band of synchronization based on an objective criterion? These questions were addressed by chronic extracellular recordings of neuronal activity in primary visual cortex of awake behaving cats: 1) Visual stimulation induces neuronal synchronization in a broad and high frequency range. 2) This synchronization is selective for the orientation of a visual stimulus. 3) By analyzing the stimulus selectivity of synchronization a functional band of neuronal synchronization can be defined from about 45 to 120 Hz. These results from animals behaving under natural conditions show a surprisingly broad spectral distribution of synchronization that extends well beyond typically investigated frequency ranges. These results cast doubt on the hypothesis of cortical high-frequency synchronizations as a spectrally sharp and static phenomenon.
134

Le conservatisme américain en mouvement : enquête sur le Tea Party en Pennsylvanie / American conservatism on the move(ment) : a study of the Tea Party in Pennsylvania

Douzou, Marion 05 December 2017 (has links)
La Pennsylvanie est un État complexe dans sa géographie économique, urbaine et raciale et, partant, dans les comportements électoraux de ses citoyens. Cette thèse examine la manière dont le Tea Party s’y est organisé et les modes de mobilisation qu’il a adoptés. Fort d’une tradition conservatrice souvent sous-estimée, l'État de William Penn constitue un bon observatoire pour étudier l'évolution et les mutations du mouvement conservateur et de son bras armé électoral, le Parti républicain. L’observation de terrain démontre que le Tea Party ne peut pas être appréhendé indépendamment d’une large galaxie de groupes nationaux et locaux, de think tanks, de médias avec lesquels il entretient des relations souvent conflictuelles.La thèse met en lumière la mutation d’un mouvement social médiatisé en une mobilisation politique dont les efforts se concentrent à l’échelle fédérée et locale. Rétifs à toute institutionnalisation, les groupes locaux voudraient restituer aux citoyens des processus de décision que l’appareil républicain aurait confisqués à son profit. Stratégie d’entrisme, pressions sur les élus, travail idéologique d’organisations de terrain, action concertée au Congrès ont fait glisser le centre de gravité du GOP vers un conservatisme pour lequel la capacité à nouer des compromis pour gouverner est disqualifiée. En dépit d’une force militante en recul, la nébuleuse Tea Party soumet idéologiquement le mouvement conservateur et le Parti républicain à de fortes pressions qui ne sont pas étrangères à la confusion qui caractérise la situation politique actuelle du pays. / Pennsylvania is a complex state in its economic, urban, and racial geographies, accordingly complex is the electoral behavior of its citizens. This thesis examines the ways in which Tea Party groups in Pennsylvania mobilized and organized. The often overlooked conservative tradition of William Penn’s state makes it an excellent case study to examine the evolution and mutations of the conservative movement and of its electoral arm, the Republican party. The fieldwork conducted in this thesis shows that the Tea Party cannot be understood without taking into account a great number of national and local groups, think tanks, and media personalities with whom it often has chaotic relationships.This work focuses on the evolution of a visible social movement into a political mobilization that targets the state and local levels. Local Tea Party groups, who are opposed to any form of institutionalization, fight to snatch power from the hands of the GOP establishment to give it back to the voters. Gradual infiltration of the Republican party, constant pressure on elected officials, ideological work conducted by advocacy organizations, and concerted action in Congress have driven the GOP towards a brand of conservatism that rejects any idea of compromise in governing. Despite a drop in the number of activists, the Tea Party movement has subjected the conservative movement and the Republican party to heavy ideological pressure, which partly explains the current confusion in the country’s political landscape.
135

Bottom-up and top-down processes in reading : influences of frequency and predictability on event-related potentials and eye movements

Dambacher, Michael January 2010 (has links)
In reading, word frequency is commonly regarded as the major bottom-up determinant for the speed of lexical access. Moreover, language processing depends on top-down information, such as the predictability of a word from a previous context. Yet, however, the exact role of top-down predictions in visual word recognition is poorly understood: They may rapidly affect lexical processes, or alternatively, influence only late post-lexical stages. To add evidence about the nature of top-down processes and their relation to bottom-up information in the timeline of word recognition, we examined influences of frequency and predictability on event-related potentials (ERPs) in several sentence reading studies. The results were related to eye movements from natural reading as well as to models of word recognition. As a first and major finding, interactions of frequency and predictability on ERP amplitudes consistently revealed top-down influences on lexical levels of word processing (Chapters 2 and 4). Second, frequency and predictability mediated relations between N400 amplitudes and fixation durations, pointing to their sensitivity to a common stage of word recognition; further, larger N400 amplitudes entailed longer fixation durations on the next word, a result providing evidence for ongoing processing beyond a fixation (Chapter 3). Third, influences of presentation rate on ERP frequency and predictability effects demonstrated that the time available for word processing critically co-determines the course of bottom-up and top-down influences (Chapter 4). Fourth, at a near-normal reading speed, an early predictability effect suggested the rapid comparison of top-down hypotheses with the actual visual input (Chapter 5). The present results are compatible with interactive models of word recognition assuming that early lexical processes depend on the concerted impact of bottom-up and top-down information. We offered a framework that reconciles the findings on a timeline of word recognition taking into account influences of frequency, predictability, and presentation rate (Chapter 4). / Wortfrequenz wird in der Leseforschung als wesentliche Bottom-up Determinante für die Geschwindigkeit des lexikalischen Zugriffs betrachtet. Darüber hinaus spielen Top-down Informationen, wie die kontextbasierte Wortvorhersagbarkeit, in der Sprachverarbeitung eine wichtige Rolle. Bislang ist die exakte Bedeutung von Top-down Vorhersagen in der visuellen Worterkennung jedoch unzureichend verstanden: Es herrscht Uneinigkeit darüber, ob ausschließlich späte post-lexikalische, oder auch frühe lexikalische Verarbeitungsstufen durch Vorhersagbarkeit beeinflusst werden. Um ein besseres Verständnis von Top-down Prozessen und deren Zusammenhänge mit Bottom-up Informationen in der Worterkennung zu gewährleisten, wurden in der vorliegenden Arbeit Einflüsse von Frequenz und Vorhersagbarkeit auf ereigniskorrelierte Potentiale (EKPs) untersucht. Die Ergebnisse aus mehreren Satzlesestudien wurden mit Blickbewegungen beim natürlichen Lesen sowie mit Modellen der Worterkennung in Beziehung gesetzt. Als primärer Befund zeigten sich in EKP Amplituden konsistent Interaktionen zwischen Frequenz und Vorhersagbarkeit. Die Ergebnisse deuten auf Top-down Einflüsse während lexikalischer Wortverarbeitungsstufen hin (Kapitel 2 und 4). Zweitens mediierten Frequenz und Vorhersagbarkeit Zusammenhänge zwischen N400 Amplituden und Fixationsdauern; die Modulation beider abhängigen Maße lässt auf eine gemeinsame Wortverarbeitungsstufe schließen. Desweiteren signalisierten längere Fixationsdauern nach erhöhten N400 Amplituden das Andauern der Wortverarbeitung über die Dauer einer Fixation hinaus (Kapitel 3). Drittens zeigten sich Einflüsse der Präsentationsrate auf Frequenz- und Vorhersagbarkeitseffekte in EKPs. Der Verlauf von Bottom-up und Top-down Prozessen wird demnach entscheidend durch die zur Wortverarbeitung verfügbaren Zeit mitbestimmt (Kapitel 4). Viertens deutete ein früher Vorhersagbarkeitseffekt bei einer leseähnlichen Präsentationsgeschwindigkeit auf den schnellen Abgleich von Top-down Vorhersagen mit dem tatsächlichen visuellen Input hin (Kapitel 5). Die Ergebnisse sind mit interaktiven Modellen der Worterkennung vereinbar, nach welchen Bottom-up und Top-down Informationen gemeinsam frühe lexikalische Verarbeitungsstufen beeinflussen. Unter Berücksichtigung der Effekte von Frequenz, Vorhersagbarkeit und Präsentationsgeschwindigkeit wird ein Modell vorgeschlagen, das die vorliegenden Befunde zusammenführt (Kapitel 4).
136

Nahrungsnetzbewirtschaftung in Mittelgebirgstalsperren

Scharf, Wilfried 14 November 2004 (has links) (PDF)
"Biomanipulation" was carried out in order to try and improve the water quality of six deep reservoirs situated in the catchment area of the River Wupper. All the reservoirs are deep, dimictic soft-water lake types, covering a range from oligo-/mesotrophic to eutrophic. Although changing the fishery management only by repeated fish stocking, in combination with implementating size and bag limits for recreational fisheries, is thought to have only limited success, we decided to put this type of "Biomanipulation" into practice. This whole-lake biomanipulation experiment, covering a time scale of more than ten years, aimed to address the following questions: 1. Is such a fishery-management strategy a useful water quality management tool in deep reservoirs, not only in maintaining but also in sustaining the best water quality conditions in relation to the given nutrient concentrations? 2. What are the underlying mechanisms? With the exception of the oligotrophic Große Dhünn Reservoir, "Biomanipulation" resulted in a shift of zooplankton body-size structure to larger daphnids in all the reservoirs. The underlying switch in the size shift from Daphnia cucullata to Daphnia galeata (Bever-Reservoir, Wupper-R, Lingese-R), or only in increasing individual body sizes of the Daphnia galeata population (Vorsperre Große Dhünn), occurred suddenly but only some years after the changes in fishery management were implemented. Our records of the fish stock suggest that indirect effects, presumably resulting from predator avoidance, must be a driving force. An increase of zooplankton body-size structure always resulted in an improvement in secchi-disk depth, often accompanied by a vertical restructuring of the water column favouring the development of metalimnetic algal populations. A decrease in summer chlorophyll concentrations in the trophogenic zone was only achieved in the slightly eutrophic reservoirs. This decrease in chlorophyll concentration was always accompanied by a decrease in the total phosphorus concentration in summer, while the total phosphorus concentration in spring remained unchanged. Thus, reduced P-availability, due to an increased vertical phosphorus flux, caused algal biomass to decline.These results support predictions from the size-efficiency hypothesis (Brooks & Dodson, 1965) but not those from the trophic cascade hypothesis (Carpenter et al., 1985). Undoubtedly the results underline the importance of indirect effects with respect to a successful "Biomanipulation" as predicted from the hypothesis of Biomanipulation Efficiency Threshold of P-loading (Benndorf, 1987). In summary, implementation of a correct fishery management strategy was shown to be a useful water quality management tool, not only in maintaining but also in sustaining the best water quality conditions, in relation to the given nutrient concentrations in these deep reservoirs. / In sechs Mittelgebirgstalsperren im Einzugsgebiet der Wupper erfolgte eine Umstellung der fischereilichen Bewirtschaftung mit dem Ziel, die Gewässergüte dieser Talsperren durch Absenkung der Zooplanktivorie zu verbessern und auf einem hohen Niveau zu stabilisieren. Vom Gewässercharakter her handelt es sich bei den Talsperren um klare tiefe Weichwasserseen, welche den oligo-/mesotrophen bis eutrophen Bereich abdecken. Die hier genutzte Methode einer ordnungsgemäßen fischereilichen Bewirtschaftung (Nahrungsnetzbewirtschaftung), welche sich zum Auf- und Umbau der Fischbestände auf Besatz- und Hegemaßnahmen stützt und dabei bewusst auf massive Eingriffe verzichtet, gelangte bisher nur in wenigen Fällen zur ausschließlichen Anwendung und wird allgemein als wenig erfolgversprechend eingestuft. Ziel dieser mehrjährigen Ökosystemuntersuchungen mit anwendungsorientiertem Ansatz ist eine Antwort auf die Frage nach der Praxistauglichkeit und den Grenzen des Instruments der Nahrungsnetzbewirtschaftung in Mittelgebirgstalsperren. Die Analyse der Ergebnisse versucht die zugrundeliegenden Mechanismen und Randbedingungen herauszuarbeiten, welche für die Wirkungsentfaltung der den Erfolg einer Nahrungsnetzbewirtschaftung tragenden Kräfte auf ökosystemarer Ebene verantwortlich sind. Mit Ausnahme der oligotrophen Großen Dhünn-Talsperre konnte in allen Gewässern eine adäquate Reaktion des Zooplanktons durch Umstellung der fischereilichen Bewirtschaftung erzielt werden. Im Einklang mit der Hypothese einer kritischen Schwelle der Planktivorie erfolgten die Reaktionen sprunghaft, aber erst nach mehreren Jahren und manifestieren sich durch einen "switch" von Daphnia cucullata zum größeren Daphnia galeata-Komplex (Bever-Talsperre, Wupper-T, Lingese-T), teils durch Körpergrößenzunahme des Daphnia galeata-Komplexes (Vorsperre Große Dhünn). Wie die Fischbestandsdaten nahe legen, kommt den indirekten, vermutlich aus einer Räuber-Vermeidungsreaktion resultierenden Effekten, hierbei eine Schlüsselposition zu. Parallel mit der Veränderung des Zooplankton-Größenspektrums kommt es stets zu einer Erhöhung der sommerlichen Sichttiefen, welche vielfach von einer vertikalen Neustrukturierung der Algenentwicklung im Wasserkörper begleitet ist. Eine Absenkung der sommerlichen Chlorophyll-Konzentrationen in der trophogenen konnte hingegen nur in den schwach eutrophen Talsperren beobachtet werden und war stets von einer erhöhten Absenkung der sommerlichen gegenüber den frühjährlichen Gesamtphosphor-Konzentrationen begleitet. Entsprechend muss die Absenkung der sommerlichen Chlorophyll-Konzentrationen auf eine erhöhte Phosphor-Sedimentation zurückgeführt werden.Die Ergebnisse der fischereilichen Bewirtschaftungsmaßnahmen stehen im Einklang mit den Vorhersagen der size-efficiency Hypothese (Brooks & Dodson, 1965), stützen aber nicht die Vorhersagen der trophic cascade Hypothese (Carpenter et al., 1985). Demgegenüber unterstreichen sie die Bedeutung indirekter Effekte, wie sie durch die These einer "Biomanipulationseffektivitätsschwelle der Phosphor-Belastung" (Benndorf, 1987) formuliert werden. Insgesamt erweist sich das Instrument der Nahrungsnetzbewirtschaftung als zwingender Baustein einer integrierten Wasserwirtschaft zur Sicherung der Gewässergüte in Mittelgebirgstalsperren, dessen soziökonomische Aspekte in der Arbeit angesprochen werden.
137

Top-down and bottom-up excursions beyond the standard model : the example of left-right symmetries in supersymmetry / Excursions « top-down » et « bottom-up » au-delà du modèle standard : l'exemple des symétries gauches-droites en supersymétrie

Alloul, Adam 20 September 2013 (has links)
Une très grande effervescence secoue le monde de la physique des particules depuis le lancement du grand collisionneur de hadrons (LHC) au CERN. Cette énorme machine capable de faire se collisionner des protons à des énergies égales à 14 TeV promet de lever le voile sur la physique régissant les interactions à ces échelles d’énergies. Ces résultats sont d’autant plus attendus que l’on a acquis la certitude que le Modèle Standard de la physique des particules est incomplet et devrait, en fait, être interprété comme la théorie effective d’une théorie plus fondamentale. Toutefois, depuis le lancement des expériences au LHC avec des énergies de 7 puis de 8 TeV aucun signe de nouvelle physique n’a été découvert. Par contre, un énorme bond en avant a été franchi avec la découverte d’une particule scalaire de masse égale à 125 GeV et dont les propriétés sont relativement proches de celles du boson de Higgs telles que prédites par le Modèle Standard. C’est dans ce contexte de forte émulation internationale que mon travail de thèse s’est inscrit. Dans un premier temps, nous avons voulu explorer la phénoménologie associée au secteur des neutralinos et charginos du modèle supersymétrique symétrique gauche-droit. Cette étude peut être motivée par plusieurs raisons notamment le fait que leur caractère supersymétrique apporte une solution au problème dit de la hiérarchie mais implique aussi l’unification des constantes de jauge ainsi que l’explication de la matière noire. L’introduction de la symétrie entre les fermions gauchers et les fermions droitiers permet, quant à elle, d’expliquer naturellement, via le mécanisme dit de la balançoire, la petitesse de la masse des neutrinos mais aussi de répondre à plusieurs autres questions non solubles dans le cadre du Modèle Standard. Nous concentrant uniquement sur le secteur des charginos et neutralinos les plus légers, nous avons montré que ces modèles peuvent être facilement mis en évidence dans les évènements multi-leptoniques en ce sens que les signatures qu’ils induisent sont tr`es différentes comparées à celles du Modèle Standard et de sa version supersymétrique.[...] / The field of high-energy physics has been living a very exciting period of its history with the Large Hadron Collider (LHC) at CERN collecting data. Indeed, this enormous machine able to collide protons at a center of mass energy of 14 TeV promises to unveil the mystery around the physics at such energy scales. From the physicists side, the expectations are very strong as it isnowadays a certitude that the Standard Model of particle physics is incomplete and should, in fact, be interpreted as the effective theory of a more fundamental one. Unfortunately, the 7 and 8 TeV runs of the LHC did not provide any sign of new physics yet but there has been at least one major discovery in 2010, namely the discovery of a scalar particle with a mass of 125 GeV and whichproperties are very close to those of the Standard Model Higgs boson. Since then, many questions have come up as we now want to understand if it really is the Standard Model Higgs boson or if it exhibits any deviations. It is in this peculiar context that my research work was carried. In a first project, we, my supervisors, our collaborator and I, have wanted to explore thephenomenology associated with the neutralinos and charginos sector of the left-right symmetric supersymmetric model. Such an analysis can be motivated by several reasons such as the fact that the supersymmetric nature of these models provides a natural explanation for the infamous hierarchy problem, implies the unification of the gauge coupling constants at very high energy and provides a natural candidate for dark matter. In addition to these nice features, the left-right symmetry introduces a natural framework for explaining the smallness of neutrino masses but also helps in addressing several other unresolved issues in the Standard Model framework. Only focusing on the lightest charginos and neutralinos decaying into one or more light leptons, we have shown in our study that these models can be easily discovered in multi-leptonic final states as theylead to signatures very different from those induced by the Standard Model or its supersymmetric version.[...]
138

Consumo energético nos setores industriais brasileiros: uma avaliação de desempenho e estratégias para a redução da emissão de CO2 / Energy consumption in the industrial sectors in Brazil: an evaluation of performance and strategies to reduce CO2 emissions

Flávia de Castro Camioto 04 October 2013 (has links)
Em um período de mudanças climáticas e restrições a emissões cada vez maiores, é importante focar o desenvolvimento das nações na direção de uma economia de baixo carbono. O elevado consumo de combustíveis fósseis gera danos que atingem escalas globais, regionais e locais e põem em risco o suprimento de longo prazo no planeta. O presente trabalho tem como objetivo analisar o desempenho dos principais setores industriais brasileiros considerando seus respectivos consumos energéticos e contribuições para aspectos sociais e econômicos do país. Além disso, busca-se mensurar os benefícios ambientais, no que diz respeito à emissão de CO2, resultante da alteração de energéticos nos setores industriais de menor desempenho e discutir políticas públicas que visam estimular a utilização de fontes de energia mais limpas. Para atingir o objetivo proposto, foi realizada a análise e quantificação da potencial contribuição ambiental que a alteração da matriz energética dos setores com menor desempenho em relação à sua contribuição para o desenvolvimento sustentável, pode fornecer. Para determinar o desempenho dos setores foi utilizada a Análise Envoltória de Dados (DEA). Os resultados deste estudo indicaram que o setor metalúrgico e o setor de não metálicos são os que possuem o menor desempenho, considerando as variáveis selecionadas. Já para medir as emissões de CO2 dos principais combustíveis utilizados nos setores de menor desempenho foi utilizado o método Top-Down proposto pelo IPCC. A análise indicou que, apesar do carvão vegetal ser o segundo emissor de CO2, ele pode contribuir para a redução do aquecimento global, desde que seja proveniente de mata de reflorestamento destinada para a atividade industrial. Por fim, foi realizada uma breve discussão sobre as políticas públicas voltadas a este energético. / In a period of climate change and of an increasingly restriction of emissions, it is pivotal to focus on a development by countries towards an economy revolved on low carbon dioxide levels. The high consumption of fossil fuels results in damages on a global, regional and local level threatening long-term supply in our planet. This work has as its objective to analyze the performance of the main Brazilian industrial sectors considering their energy consumption and contributions to social and economic aspects of the country. In addition, will be measure the environmental benefits, in terms of CO2 emissions, resulting from fuel substitution in the industrial sectors of lower performance and discuss public policies aimed at stimulating the use of cleaner energy sources. So as to achieve this objective, an analysis and measurement assertion of the potential environmental contribution that a change of the energy matrix, of the sectors with lower performance as regards to its contribution to sustainable development of the country, may provide was performed. Data Envelopment Analysis (DEA) was used to determine the efficiency of the sectors. The results of this study indicated that the metallurgical and nonmetallic sectors are the ones that have the lowest performance industrial in terms of sustainable. For the measurement of CO2 emissions for each major fuel used in the sectors with lower performance, the Top-Down method proposed by the IPCC was used. This analysis indicated that, although charcoal is the second fuel in sectors that emit more CO2, it can contribute to the reduction of global warming since it comes from forest reforestation destined for the activity industrial. Finally, a brief discussion about public policies on this fuel was held.
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Em busca da reinvenção do ensino médio: o caso de duas escolas da Superintendência Regional de Ensino de Caratinga

Calegar, Margarette Alves Rodrigues 13 August 2014 (has links)
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No. of bitstreams: 1 margarettealvesrodriguescalegar.pdf: 1127133 bytes, checksum: 95ef15e7cba1fc847acecf08f8857a89 (MD5) Previous issue date: 2014-08-13 / Esta dissertação, desenvolvida no âmbito do Mestrado Profissional em Gestão e Avaliação da Escola Pública, tem como objeto de estudo o Projeto Reinventando o Ensino Médio, elaborado pela Secretaria de Estado de Educação de Minas Gerais, implementado progressivamente por meio de um projeto piloto a partir de 2012, como currículo oficial nas escolas estaduais mineiras. Este estudo contemplaria a extensão do projeto, em 2013, em duas escolas da jurisdição da Superintendência Regional de Ensino, da cidade de Caratinga, que aqui serão identificadas, com nomes fictícios por questões éticas para com os sujeitos envolvidos, como Escola Renascer e Escola Construindo. O Reinventando o Ensino médio é uma proposta da Secretaria de Estado de Educação que se destina a dar um novo significado ao ensino médio. São objetivos específicos deste trabalho: identificar o contexto histórico da construção do projeto, para melhor compreensão do mesmo por parte da comunidade escolar; avaliar o processo de expansão do projeto em 2013, com foco nas duas escolas citadas; identificar as dificuldades encontradas por essas escolas; comparar o processo de implementação entre as duas escolas; identificar o papel da equipe gestora na condução da implementação do projeto. Diversos estudos indicam a necessidade de reformulação do ensino médio, que no decorrer da história da Educação Brasileira oscilou entre a formação geral do jovem como preparação para o curso superior e a formação para o trabalho. Nesse cenário, o Projeto Reinventando o Ensino Médio vem ao encontro da ressignificação desse nível de ensino e, considerando minha atuação na Superintendência Regional de Ensino de Caratinga como Analista Educacional, justifico a escolha do tema por fazer parte do meu trajeto profissional e pela necessidade de verificar se o processo de implementação do mesmo está ocorrendo de forma a atender a ressignificação do ensino médio para uma melhor formação dos jovens. A metodologia utilizada contempla a análise de documentos oficiais, observação não participante nas escolas pesquisadas e pesquisa de campo por meio de entrevistas e questionários com os atores educacionais envolvidos na implementação do mesmo nas duas escolas e na Superintendência. A partir daí, percebe-se que o modelo de política utilizada na implementação do Reinventando o Ensino Médio é de caráter top/down e, como consequência, há certa limitação na realização da prática pedagógica exigida pelo projeto, fundamentada na interdisciplinaridade. A análise aqui estabelecida tem como referencial teórico autores que apresentam uma contextualização do ensino médio, Moehlecke (2012), Bello (2001), Bueno (2000), Peregrino (2010), Lima (2011), e os autores Jefferson Mainardes (2006) e Eduardo Conde (2012), que esclarecem questões sobre o Ciclo de Políticas. Esta dissertação analisa um caso de gestão, para o qual foi elaborado um Plano de Ação Educacional propondo ações que otimizem a implementação do projeto nas escolas pesquisadas e a participação dos gestores de tais escolas na extensão do projeto às demais escolas de ensino médio da Superintendência Regional de Ensino de Caratinga. As ações propostas para a otimização do projeto são a avaliação institucional, as assembléias REM, a reorganização da prática pedagógica e um sistema de monitoria. Como proposta de participação efetiva dos gestores, apresentamos a intervenção em âmbito regional. / This dissertation is a Professional Master in Management and Evaluation of Public School whose object of study is the project Reinventing High School, prepared by the State Department of Education of Minas Gerais , progressively implemented through a pilot project from 2012 as the official curriculum in the state schools of the state of Minas Gerais . This study will include the extension of the project in 2013 , two schools in the jurisdiction of the Regional Superintendent of Education , the city of Caratinga , which here will be identified as Reborn School (Escola Renascer) and School Building (Escola Construindo). The Reinventing High School is a proposal by the State Department of Education which is intended to give a new meaning to high school. The specific objectives of the study are : to identify the historical context of project construction for better understanding of it by the school community ; evaluate the process of expansion of the project in 2013 , focusing on the two aforementioned schools; identify the difficulties encountered by these schools ; compare the implementation process between the two schools ; identify the role of the management team in driving the implementation of the project . Several studies indicate the need to redesign the high school , which throughout history of Brazilian Education fluctuated between general education of the young in preparation for higher studies and training for work, Reinventing High School Project meets reconsidering this level of education and considering my performance in the Regional Superintendent of Education of Caratinga as Analyst educational , I justify the choice of topic for being part of my professional career and the need to verify if the process of implementing the project is occurring in order to meet reframing of high school to better training of our youth . The methodology includes the analysis of documents , observation without interference in the schools surveyed and field research through interviews and questionnaires with educational stakeholders in the implementation of the same in the two schools and the Superintendent . And it is perceived by it that the policy model used in the implementation of Reinventing High School is the character top / down , and as a consequence there is some limitation in achieving pedagogical practice required by the project , based on interdisciplinarity . The analysis established here as theoretical reference authors present a contextualization of high school , Moehlecke (2012) , Bello (2001) , Bueno (2000) , Pilgrim (2010) , Lima (2011) , and the authors Mainardes Jefferson (2006) and Eduardo Conde (2011) , who clarify questions about the Policy Cycle . This dissertation examines a case management and it was prepared for Educational Action Plan which proposes actions that optimize the project implementation in the surveyed schools and participation of managers of these schools in the extension of the project to other high schools in the Regional Superintendent of Education Caratinga . The actions proposed for project optimization are the institutional assessment, REM (Reinventing High School Project) assemblies, the reorganization of the pedagogical practice and a monitoring system. And to proposed effective participation of managers present intervention in the regional level.
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Institutions and Development : Analysis of the Effects of Institutional Environment on Agricultural Performance in Cambodia / Institutions et développement : analyse des effets de l’environnement institutionnel sur la performance agricole au Cambodge

Vin, Pheakdey 02 April 2012 (has links)
L’objectif de cette thèse est de découvrir si l’environnement institutionnel affecte la performance agricole dans le cas du Cambodge et comment le premier influe sur la dernière. Pour répondre à cet objectif, trois hypothèses sont formulées : (1) l’environnement institutionnel joue un rôle important dans la protection des droits de propriété foncière ; (2) les droits de propriété foncière sécurisés augmentent la productivité agricole par la stimulation des incitations d’investissement des agriculteurs ; (3) les droits de propriété foncière sécurisés accroissent la productivité agricole par la facilitation de l’accès au crédit formel. Méthodologiquement, la recherche est basée sur les différentes théories de la Nouvelle Economie Institutionnelle, qui expliquent que les institutions déterminent la structure des incitations des acteurs économiques dans une société. Spécifiquement, les institutions politiques déterminent les institutions économiques, c’est-à-dire les droits de propriété, qui à leur tour affectent la performance économique en général et la performance agricole en particulier. La recherche est également basée sur les données venant de diverses sources, telles que des agences gouvernementales, des instituts de recherche locaux, des organisations non-gouvernementales et des organisations internationales, qui sont susceptibles de servir de base pour des analyses empiriques. En outre, le cas de l’Afrique subsaharienne est également étudié à titre de comparaison. Le résultat de la thèse confirme fortement les deux premières hypothèses, mais peu la dernière. Le résultat indique que l’impact de l’environnement institutionnel sur la productivité agricole via la protection des droits de propriété foncière est lié au contexte particulier parce qu’il devrait être complété par un environnement économique favorable, tel que l’infrastructure physique et la technologie agricole améliorées et les institutions du marché développées. De plus, on apprend que les résultats désirés ne sont pas obtenus si les institutions formelles (c’est-à-dire, l’enregistrement formel des terres) sont imposées via l’approche top-down dans les régions où les institutions informelles existantes sont fortement encastrées. / The purpose of this dissertation is to find out if the institutional environment affects agricultural performance in the case of Cambodia and how the former exerts an influence on the latter. To respond to this purpose, three hypotheses are formulated: (1) the institutional environment plays an important role in protecting property rights in land; (2) secure property rights in land increase agricultural productivity through the stimulation of farmers’ investment incentives; (3) secure property rights in land raise agricultural productivity through the facilitation of access to formal credit. Methodologically, the research is based on different theories of New Institutional Economics, which explain that institutions determine the incentive structure of economic actors in society. Specifically, political institutions shape economic institutions, i.e. property rights, which in turn affect economic performance in general and agricultural performance in particular. The research is also based on the data from various sources, such as government agencies, local research institutes, non-governmental organizations, and international organizations, which can serve as a basis for empirical analyses. In addition, the case of Sub-Saharan Africa is also studied for comparison. The result of the dissertation confirms strongly the first two hypotheses but slightly the last one. The result indicates that the impact of institutional environment on agricultural productivity through the protection of property rights in land is context-specific because it should be complemented by a favorable economic environment, such as improved physical infrastructure and agricultural technology and developed market institutions. Furthermore, it is learned that, in developing countries, the desired outcomes will not be obtained if formal institutions (i.e., formal land registration) are imposed through a top-down approach in areas where the existing informal institutions are strongly embedded.

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