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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.
181

LO STAGE SPERIMENTALE NELLA SOCIAL WORK EDUCATION. UNA RICERCA ESPLORATIVA SUL MODELLO DELL'UNIVERSITA' CATTOLICA DEL SACRO CUORE

SALA, MARTINA 24 March 2017 (has links)
Questo lavoro di ricerca si colloca nell’ambito della Social Work Education e indaga gli Stage sperimentali in Servizio sociale, una nuova forma di tirocinio proposta al terzo anno del corso di laurea in Scienze del Servizio Sociale dell’Università Cattolica del Sacro Cuore di Milano e Brescia. La tesi osserva l’evoluzione della professione di assistente sociale e della sua formazione, dedica attenzione alla Social Work Education di stampo relazionale ed in particolare a delle esperienze di campo innovative a livello internazionale. La parte empirica si concentra sugli Stage sperimentali: attraverso uno strumento originale sono stati raccolti 315 questionari on-line da laureati tra l’anno accademico 2008-2009 e 2014-2015 che hanno sostenuto questa attività. L’indagine ha osservato le caratteristiche fondamentali dei progetti realizzati sul campo e ha riscontrato continuità con il modello teorico degli Stage basato sull’approccio relazionale; si è infatti rilevata la presenza negli Stage sperimentali di: costruzione partecipata delle progettualità, ingaggio di collaboratori riflessivi non necessariamente professionali, innovazione relativa rispetto al contesto. Si è anche rilevato il proseguire di un numero rilevante progetti al termine degli Stage curricolari grazie al contributo dei partner coinvolti e lo scaturire dalle esperienze di Stage di nuove occasioni di lavoro per i neo assistenti sociali. / This study takes palce in the field of Social Work Education and investigates the Social Work Unconventional Placements, a new frame of placement proposed at the third year of Catholic University Social Work degree (Milan-Brescia). The thesis argues the evolution of Social Work profession and its education, giving attention to the Relational-way of Social Work Education and to international innovative practice learning experiences. The research project focused on Unconventional Placement inspired by Relational Social Work method. To collect data and opinions of UC Social Work bachelors an original survey was created. The on-line survey was administered to 315 former-social work students that practiced this activity in 2008-2015. The research explored the main characteristics of the Unconventional Placements realized by the students during their Social work education path. Findings from the study confirmed the presence of distinctive traits related to the theoretic model of Unconventional Placement developed in Relational SWE framework: participatory approach to projects, reflexive involvement of professional/non-professional partners, innovation in the specific context. The survey observes the carry on of a considerable number of projects after the end of curricular placements, through the community project partners activation; from Unconventional Placements emerge new job opportunities for new social workers involved.
182

GéoMicrobiologie de la méthanogenèse dans les schistes immatures du bassin de Paris / GeoMicrobiology of methanogenesis in immature organic-rich shales of the Paris Basin

Meslé, Margaux 29 January 2013 (has links)
L’exploitation des ressources naturelles non conventionnelles en substitution du pétrole est un des défis du 21e siècle. La transformation microbiologique in situ de ces ressources en méthane est une des voies les plus prometteuses développées aujourd’hui mais son application reste à démontrer. Mes objectifs ont été de démontrer l'existence d'une conversion microbiologique en méthane de la matière organique (MO) de schistes immatures et de la quantifier pour extrapoler la production potentielle de méthane à l’échelle d’un bassin sédimentaire. Une méthode de détection et de suivi des consortia méthanogènes des schistes cartons en microcosmes, par une combinaison de PCR quantitative, GC-FID et pyrolyse Rock-Eval, a été mise au point et validée. Elle a été appliquée à l’étude de la distribution spatiale des méthanogènes dans les schistes cartons du bassin de Paris et à la démonstration de la méthanisation de la MO de ces roches. Les résultats montrent comme attendu la conversion des fractions solubles de la MO (bitume) par un consortium méthanogène isolé des schistes, mais également la transformation d’une fraction plus complexe (kérogène). L’absence de corrélation stricte entre la lithologie et la présence de méthanogènes actifs rend l’extrapolation au niveau du bassin plus difficile, mais la localisation des méthanogènes à la fois dans et hors les zones riches en MO constitue un avantage certain dans l'optique d'une exploitation économique de ces ressources. Ces travaux démontrent un potentiel élevé de production microbiologique de méthane dans le bassin de Paris et ouvrent la voie vers des études de faisabilité et rentabilité économique à l’échelle d’un site de production. / The exploitation of natural unconventional resources in substitution for petroleum is one of the challenges of the 21st century. In situ microbial transformation of these resources in methane is one of the most promising pathway currently developed, although its application needs to be demonstrated. My objectives were to demonstrate the existence of a microbial conversion into methane of the organic matter (OM) of immature shales, and to quantify it in order to extrapolate the potential for methane production of the rocks at the sedimentary basin scale. A method of detection and monitoring of methanogenic consortia from paper shales in microcosms, combining quantitative PCR, GC-FID and Rock-Eval pyrolysis, was developed and validated. It was used to study the spatial distribution of methanogens in paper shales of the Paris Basin and to demonstrate the methanization of the OM of these rocks. The results show the conversion of the soluble fractions of the OM (bitumen) by methanogenic consortia isolated from shales, but also the transformation of a more complex fraction (kerogen). No strict correlation was established between lithology and presence of active methanogens, which makes the extrapolation of methane production to the basin scale more difficult. However, the localization of methanogens in both OM-rich and OM-poor zones constitute an advantage in the perspective of an economic exploitation of these resources. This work demonstrates a great potential for microbial methane production in the Paris Basin and paves the way to studies of economic feasibility and profitability on the scale of a production site.
183

Účinnost nekonvenční měnové politiky na nulové spodní hranici úrokových sazeb: využití DSGE přístupu / The Effectiveness of Unconventional Monetary Policy Tools at the Zero Lower Bound: A DSGE Approach

Malovaná, Simona January 2014 (has links)
The central bank is not able to further ease monetary conditions once it ex- hausts the space for managing short-term policy rate. Then it has to turn its attention to unconventional measures. The thesis provides a discussion about the suitability of different unconventional policy tools in the Czech situation while the foreign exchange (FX) interventions have proven to be the most appropriate choice. A New Keynesian small open economy DSGE model estimated for the Czech Republic is enhanced to model the FX interventions and to compare dif- ferent monetary policy rules at the zero lower bound (ZLB). The thesis provides three main findings. First, the volatility of the real and nominal macroeconomic variables is magnified in the response to the domestic demand shock, the for- eign financial shock and the foreign inflation shock. Second, the volatility of prices decreases significantly if the central bank adopts price-level or exchange rate targeting rule. Third, intervening to fix the nominal exchange rate on some particular target or to correct a misalignment of the real exchange rate from its fundamentals serves as a good stabilizer of prices while intervening to smooth the nominal exchange rate movements increases the overall macroeconomic volatility at the ZLB. 1
184

Structural and dynamic characterization of the Golgi Reassembly and Stacking Protein (GRASP) in solution / Caracterização estrutural e dinâmica da proteína de estruturação e compactação do complexo de Golgi (GRASP) em solução

Mendes, Luis Felipe Santos 07 February 2018 (has links)
The Golgi complex is an organelle responsible for receiving synthesized cargo from the endoplasmic reticulum for subsequent post-translations modifications, sorting and secretion. A family of proteins named Golgi Reassembly and Stacking Proteins (GRASP) is essential for the correct assembly and laterally tethering of the Golgi cisternae, a necessary structuration to keep this organelle working correctly. The GRASP structure is mainly composed of two regions: an N-terminal formed by two PDZ domains connected by a short loop (GRASP domain) and a non-conserved C-terminal region, rich in serine and proline residues. Although there are now a few crystal structures solved for the N-terminal domain, it is surprising to notice that no information is currently available regarding a full-length protein or even about dynamic and structural differences between the two PDZs in solution, which is the main functional region of this protein. Using a full-length GRASP model, we were capable of detecting the coexistence of regular secondary structures and large amounts of disordered regions. The overall structure is less compact than a regular globular protein and the high structural flexibility makes its hydrophobic core more accessible to solvent. GRASP coexist in a dynamic conformational ensemble of a µs-ms timescale. Our results indicate an unusual behavior of GRASP in solution, closely resembling a class of collapsed intrinsically disordered proteins called molten globule. We report here also the disorder-to-order transition propensities for a native molten globule-like protein in the presence of different mimetics of cell conditions. Changes in the dielectric constant (such as those experienced close to the membrane surface) seem to be the major factor capable of inducing several disorder-to-order transitions in GRASP, which seems to show very distinct behavior when in conditions that mimic the vicinity of the membrane surface as compared to those found when free in solution. Other folding factors such as molecular crowding, counter ions, pH and phosphorylation exhibit lower or no effect on GRASP secondary structure and/or stability. This is the first study focusing on understanding the disorder-to-order transitions of a molten globule structure without the need for any mild denaturing condition. Regarding the PDZs that form the GRASP domain, we observed that GRASPs are formed by a more unstable and flexible PDZ1 and much more stable and structurally well-behaved PDZ2. More than that, many of the unstable regions found in PDZ1 are in the predicted binding pocket, suggesting a structural promiscuity inside this domain that correlates with the functional promiscuity of interacting with multiple protein partners. This thesis presents the first structural characterization of a full-length GRASP, the first model of how GRASPs (or any molten globule-like protein) can be modulated by the cell during different cell functionalities and the first work in the community proving that the established idea that both PDZs are structurally equivalent is not completely right / O complexo de Golgi é um organela responsável pela recepção de carga sintetizada no retículo endoplasmático e por subsequente modificações pós-traducionais, classificação e secreção. Uma família de proteínas chamada Golgi Reassembly and Stacking Proteins (GRASP) é essencial para o correto empilhamento das cisternas e conexões laterais das pilhas do complexo de Golgi, uma estruturação necessária para manter essa organela funcionando corretamente. A estrutura das GRASPs é composta de duas regiões principais: uma extensão N-terminal formado por dois domínios PDZ conectados por um loop (domínio GRASP) e uma região C-terminal não conservada, rica em resíduos de serina e prolina. Embora existam algumas estruturas cristalográficas resolvidas para o domínio N-terminal, é surpreendente notar que não havia nenhuma informação na literatura sobre a construção inteira de um GRASP, ou mesmo um estudo detalhado sobre os PDZs no N-terminal em solução, que é a principal região funcional dessa proteína. Usando um modelo de GRASP em sua construção completa, fomos capazes de detectar a coexistência de estruturas secundárias regulares e grandes quantidades de regiões desordenadas. A estrutura é menos compacta do que uma proteína globular e a alta flexibilidade estrutural torna o seu núcleo hidrofóbico mais acessível ao solvente. GRASPs coexistem em um conjunto conformacional dinâmico numa escala de tempo característico de s-ms. Nossos resultados indicam um comportamento incomum da GRASP em solução, similar à de uma classe de proteínas intrinsicamente desordenadas colapsadas conhecidas como glóbulos fundidos. Nós relatamos também as propensões de transição estrutural do tipo desordem-ordem para uma proteína glóbulo fundido nativa, induzidas pela presença de diferentes miméticos de condições celulares especificas. A mudança na constante dielétrica do meio (como as experimentadas próximas à superfície da membrana biológica) é o principal modulador estrutural, capaz de induzir múltiplas transições desordem-ordem na GRASP, sugerindo um comportamento muito distinto quando em condições que imitam a vizinhança da superfície da membrana em comparação com os encontrados quando livre em solução. Outros fatores de enovelamento, tais como o molecular crowding, contra-ions, pH e a fosforilação exibem efeitos menores (ou nenhum) na estrutura secundária e/ou estabilidade da GRASP. Este é o primeiro estudo focado na compreensão das transições desordem-ordem em uma estrutura do tipo glóbulo fundido sem que houvesse a necessidade de qualquer condição desnaturante. Em relação aos PDZs que formam o domínio GRASP, observamos que as GRASPs são formadas por um PDZ1 mais instável e flexível e um PDZ2 muito mais estável e estruturalmente bem comportado. Mais do que isso, muitas das regiões instáveis encontradas no PDZ1 estão no predito bolsão de ligação, sugerindo uma promiscuidade estrutural dentro desse domínio que se correlaciona com a promiscuidade funcional de interação com múltiplos parceiros proteicos. É apresentado nesta tese a primeira caracterização estrutural de uma GRASP em sua forma completa, o primeiro modelo de como as GRASPs (ou qualquer proteína em forma de glóbulo fundido) pode ser modulada estruturalmente pela célula durante diferentes funcionalidades e o primeiro trabalho na comunidade provando que a estabelecido ideia de que ambos os PDZs são estruturalmente equivalentes não é completamente correta
185

”Advertising Nouveau” : en studie om okonventionell marknadsföring. / “Advertising Nouveau” : a study of unconventional marketing

Gustafsson, Maria, Grönvall, Johanna January 2014 (has links)
Företag inom modebranschen står i dag inför en ökande konkurrenssituation. På grund av globaliseringen och interaktionen mellan kunder över internet, är konsumenterna idag mer medvetna än tidigare. Den största faktorn bakom den nya medvetenheten är den generation av unga människor som växt upp i en digitaliserad värld, benämnd som Generation Y. Företag får kämpa för att få konsumenternas uppmärksamhet och situationen beskrivs som ett marknadsföringskrig. Många marknadsförare misslyckas med att nå fram till konsumenterna med traditionella marknadsföringsverktyg som; reklam, PR, direktmarknadsföring och personlig försäljning. För att få uppmärksamhet av kunderna, undkomma det pågående mediebruset och differentiera sig på marknaden, tvingas företag att bli mer kreativa och aggressiva i sin marknadsföring. Vissa av de här kreativa aktiviteterna är kända som okonventionell marknadsföring. Ämnet är brett, men några av de viktigaste aspekterna är gerilla, viral och stealth marknadsföring. Gerilla marknadsföring är allmänt känt som okonventionella sätt att få företagens ord ut på gatorna. I gerilla marknadsföring ses allt som en reklambakgrund. Viral marknadsföring är känt som onlineversionen av word-of-mouth marknadsföring. Sociala medier som Facebook och bloggar, gör att informationsutbytet mellan användare går snabbt. Stealth marknadsföring är ett sätt att marknadsföra där avsändaren är okänd för kunderna. Vi ställer oss frågande till om det verkligen är så enkelt för ett företag att, med hjälp av okonventionell marknadsföring, skapa uppmärksamhet hos konsumenter. Det har lett oss in på vår frågeställning, som är att undersöka vad okonventionell marknadsföring har för påverkan, samt vilka attityder och beteenden metoden kan generera hos Generation Y. Vi har även valt att studera hur svenska moderelaterade företag på bästa vis kan använda sig av okonventionella marknadsföringsmetoder. Vi kom fram till följande resultat: Konsumenter uppfattar den här typen av marknadsföring som mer påtaglig och interagerande, jämförelsevis med traditionella medier. Faktorer som påverkar effekten av metoderna är konsumentens tidigare upplevelser och referenser. Då konsumenten från början hade en positiv eller en negativ attityd gentemot företaget, förstärktes attityden efter en okonventionell kampanj. Det var särskilt tydligt när det handlade om stealth marknadsföring. Viral marknadsföring kan vara mer lämplig för Generation Y, jämförelsevis med andra generationer, eftersom de generellt sett har mer internetvana. Okonventionell marknadsföring skapar starkare attityder och ger upphov till mer word-of-mouth, jämfört med traditionell marknadsföring. Det finns dock en risk att okonventionell marknadsföring inte leder till ett positivt köpbeteende hos konsumenten. Därför bör okonventionella kampanjer kompletteras med en mer säljdriven marknadskanal. Det innefattar dock inte modebloggar, eftersom att den kanalen räknas som mer säljfokuserad. Undersökningen visar att modereklamen ofta betraktas som traditionell och ointressant. Företagen kan då använda de här typerna av marknadsföringsmetoder för att differentiera sig från sina konkurrenter. Två faktorer är av stor betydelse i genomförandet av dessa strategier; kunskap om sin målgrupp och att ha en samstämmande image och kommunikation. Då ett företags kommunikation inte överensstämmer med hur konsumenten förväntar sig, kan det skada företaget. Vi kom även till slutsatsen att just gerilla är särskilt lämpligt för att sprida kunskap om nya eller små företag. Det är även lättare för små och trendiga företag att implementera de här metoderna, då det ofta förväntas av deras målgrupp att deras marknadskommunikation skall vara innovativ.
186

Unconventional oil and natural gas supplies and the mitigation of climate change / Pétrole et gaz naturel non conventionnels et l'atténuation du changement climatique

Pougy, Roberto 30 June 2017 (has links)
Cette thèse en économie de l'énergie et de l'environnement étend le modèle de Hotelling du type exploration-extraction avec contraintes géologiques d’Okullo, Reynes et Hofkes (2015), afin de prendre en compte des trajectoires en forme de cloche pour l’ajout de réserves empiriquement observées par Laherrère (2003). Le modèle LOGIMA proposé (Images à Long terme sur le Pétrole et le Gaz) explique qu’elles sont la conséquence de « sweet spots » géologiques : des zones privilégiées où la concentration d’hydrocarbures est la plus élevée. Le modèle LOGIMA a été calibré sur une base de données issues couvrant les sept principaux bassins de pétrole et de gaz non-conventionnels du pays. Les résultats indiquent que la nécessité d’apprentissage par la pratique pour découvrir l’emplacement des sweet spots conduit à une mise en œuvre d’un effort d’exploration également en forme de cloche, ce qui permet de réduire le risque des activités d’exploration. Par conséquent, la réponse en termes des volumes offerts par les producteurs à des chocs sur les prix dévient fonction de l’ensemble des ressources mondiales antérieurement découvertes. Ensuite, nous appliquons le modèle LOGIMA pour étudier l’impact causé par l’offre de pétrole et de gaz naturel « non-conventionnels » aux États-Unis, sur les efforts mondiaux d’atténuation du changement climatique. Nous y parvenons en associant les scénarios à long-terme générés par LOGIMA avec le modèle d’évaluation intégrée, IMACLIM-R. Cette étude analyse comment des différentes cibles de prix de pétrole affecteraient son offre aux États-Unis. Nous estimons cette interaction au moyen de trois cadres de politiques en matière de climat : le cadre « business as usual » (BAU), les contributions décidées à l’échelle nationale (NDC) et les scénarios de 2°C (2DS). Les résultats de l’exercice indiquent que les approvisionnements non-conventionnels sont fortement susceptibles d’affecter les marchés énergétiques mondiaux, mais leur impact sur les émissions mondiales de gaz à effet de serre serait limité, car les différents effets déclenchés dans des différents secteurs viendraient les équilibrer approximativement. / This thesis in energy and environmental economics extends the geological Hotelling-type extraction-exploration model from Okullo, Reynes and Hofkes (2015) in order to account for the bell-shaped reserve additions that were empirically observed by Laherrère (2003). The proposed model explains them as the result of geological “sweet spots”: premium areas within geological formations where the concentration of hydrocarbons is highest. The proposed theoretical formulation was programmed into the mathematical model LOGIMA – “Long-term Oil and Gas Images” – and calibrated on data covering the seven main unconventional oil and gas plays in the United States. Results indicate the need to learn the location of sweet spots through trial and error drillings leads to schedules of exploratory effort that allow the optimal “de-risking” of exploratory activities. As a result, the optimal response of producers to price shocks becomes contingent on the prevailing level of cumulative discoveries.We apply LOGIMA to investigate the impact, caused by the recent advent of large-scale supplies of unconventional oil and gas, in the United States, on the ongoing efforts to mitigate climate change. We do so by soft coupling long-term scenarios from LOGIMA with the integrated assessment model, IMACLIM-R, a recursive, computable general equilibrium model of integrated global energy, economy and environment systems. We analyze how different price targets, potentially pursued by the Organization of Petroleum Exporting Countries (OPEC), would affect supplies of unconventional oil and gas from the United States. We control this interplay under three climate policy frameworks: business as usual (BAU), nationally determined contributions (NDCs) and 2°C scenario (2DS). The results of the exercise show that, despite having a significant potential to affect global energy markets, unconventional oil and gas supplies would have a limited potential to affect global cumulative greenhouse gas emissions to 2040, as the different effects triggered in different sectors approximately balanced each other out.
187

Modèle géométrique de calcul : fractales et barrières de complexité / Geometrical model of computation : fractals and complexity gaps

Senot, Maxime 27 June 2013 (has links)
Les modèles géométriques de calcul permettent d’effectuer des calculs à l’aide de primitives géométriques. Parmi eux, le modèle des machines à signaux se distingue par sa simplicité, ainsi que par sa puissance à réaliser efficacement de nombreux calculs. Nous nous proposons ici d’illustrer et de démontrer cette aptitude, en particulier dans le cas de processus massivement parallèles. Nous montrons d’abord à travers l’étude de fractales que les machines à signaux sont capables d’une utilisation massive et parallèle de l’espace. Une méthode de programmation géométrique modulaire est ensuite proposée pour construire des machines à partir de composants géométriques de base les modules munis de certaines fonctionnalités. Cette méthode est particulièrement adaptée pour la conception de calculs géométriques parallèles. Enfin, l’application de cette méthode et l’utilisation de certaines des structures fractales résultent en une résolution géométrique de problèmes difficiles comme les problèmes de satisfaisabilité booléenne SAT et Q-SAT. Ceux-ci, ainsi que plusieurs de leurs variantes, sont résolus par machines à signaux avec une complexité en temps intrinsèque au modèle, appelée profondeur de collisions, qui est polynomiale, illustrant ainsi l’efficacité et le pouvoir de calcul parallèle des machines a signaux. / Geometrical models of computation allow to compute by using geometrical elementary operations. Among them, the signal machines model distinguishes itself by its simplicity, along with its power to realize efficiently various computations. We propose here an illustration and a study of this ability, especially in the case of massively parallel processes. We show first, through a study of fractals, that signal machines are able to make a massive and parallel use of space. Then, a framework of geometrical modular programmation is proposed for designing machines from basic geometrical components —called modules— supplied with given functionnalities. This method fits particulary with the conception of geometrical parallel computations. Finally, the joint use of this method and of fractal structures provides a geometrical resolution of difficult problems such as the boolean satisfiability problems SAT and Q-SAT. These ones, as well as several variants, are solved by signal machines with a model-specific time complexity, called collisions depth, which is polynomial, illustrating thus the efficiency and the parallel computational abilities of signal machines.
188

[en] HOME BIAS IN A MONETARY UNION: HOW FINANCIAL FRICTIONS AFFECT OUTPUT AND MONETARY POLICY DECISIONS / [pt] HOME BIAS EM UMA UNIÃO MONETÁRIA: FRICÇÕES FINANCEIRAS E SEUS EFEITOS NO PRODUTO E NAS DECISÕES DE POLÍTICA MONETÁRIA

DIOGO LUIZ DUARTE 12 February 2019 (has links)
[pt] Este estudo define um modelo de dois países que seguem a estrutura exposta em Gertler-Karadi (2011) e formam uma união monetária. Estudamos o impacto de fricções financeiras e os efeitos de políticas monetárias não convencionais implementadas com escopo individual e geral nos países membros desta união. Mostramos que, se os parâmetros usados para limitar o balanço das instituições financeiras forem calibrados para permitir uma alavancagem mais alta, o maior acesso a capital leva a um produto que é, ao mesmo tempo, mais alto no steady state e mais frágil a choques de qualidade de capital. Também mostramos que níveis elevados de Home Bias levam a menos compartilhamento de riscos e a uma disseminação menor de choques idiosincráticos. Por fim, esse estudo também mostra que políticas monetárias não convencionais com escopo individual podem aumentar o bem-estar consideravelmente quando o Home Bias no sistema financeiro é elevado. / [en] This study lays-out a model with two countries that follow the DSGE framework with financial intermediaries set by Gertler-Karadi (2011) and form a monetary union. We study the impact of financial frictions and the effects of union-wide and country-specific unconventional monetary policies in the union s member countries. We show that, if the parameters used to limit balance sheet size are calibrated in a way to allow for higher leverage in the banking system, the easier access to capital leads to an Output level that is, at the same time, higher in the Steady State and more fragile to Capital Quality Shocks. It s also shown that high levels of home-bias lead to lower risk-sharing and lower dissemination of idiosyncratic shocks, which helps explaining why idiosyncratic shocks may cause highly persistent effects in the member countries. Finally, this study also shows that country-specific unconventional monetary policies can be considerably welfare increasing when home-bias in the financial system is high.
189

Study of magnetic fluctuations and ordering in uranium compounds by heat capacity and neutron scattering measurements

Entwisle, Oliver John January 2018 (has links)
URhGe is the first ferromagnet discovered that shows superconductivity at ambient pressure. It shows a rich temperature-magnetic field phase diagram with a re-emergence of superconductivity at high magnetic field where the moments rotate. This suggests that the quantum fluctuations associated with the moment rotation may provide the pairing interaction for superconductivity. The objective of this thesis was to study these critical fluctuations with inelastic neutron scattering and heat capacity measurements, using the latter to test the bulk nature of the superconductivity and determine the types of gap nodes to help test this hypothesis. To perform the heat capacity measurements, it was necessary to develop an apparatus that measures milligram samples in the temperature range 50-1000 mK, and magnetic field range 0-12 T. The field exerts a mechanical force upon the sample, which causes it to rotate, perturbing the system destructively. The apparatus developed in this thesis overcomes this diffculty by holding the sample with tensioned kevlar wires. Testing was done by making measurements on UPt3, a well characterised superconductor. It was then used to measure URhGe in zero magnetic field. The extension to measurements in high magnetic field were not performed however, due to the structural integrity of the apparatus being weak - this was in an attempt to reduce the thermodynamic signature of the background. After many iterations of apparatus design and build, the device was proved not appropriate for high fields. A discussion of the zero-field data, as well as the design and build process, is given. The Curie temperature of URhGe is suppressed with magnetic field (applied along the b-axis), reaching zero temperature at the moment rotation transition referred to above. Small angle neutron scattering (SANS) was measured at both zero and finite fields to detect the evolution and relaxation of the critical fluctuations. The scattering is inelastic and the SANS measurement integrates over energy. Nevertheless it was possible to compare models with different dynamical dependences for the magnetic relaxation. In field, however, the magnitude of the fluctuations was strongly reduced, falling below the detection limit at half the critical field. Comparing Landau damping to various forms of non-Landau damping, a result was found that agrees with that for the ferromagnetic superconductors UGe2 and UCoGe, but the lack of critical scattering at field is found to be in contradiction with NMR measurements, which is discussed. UAu2 is a new material on the heavy fermion landscape. The crystal structure found suggests some frustrated magnetism, culminating in a Neél temperature of 43 K and a further transition at 400 mK; this suggests some new quantum criticality not seen before, and so heat capacity measurements were performed with the already-tested apparatus to see if, as the resistivity measurements suggest, a Fermi-liquid state is found. Results revealed differences between annealed and non-annealed samples in their thermodynamic signature, and the behaviour expected for antiferromagnetic spin-fluctuations is found to continue to temperatures below 150 mK, suggesting the existence of a quantum critical point. The validity of these results along with implications are discussed.
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Estudo geológico do potencial de exploração e produção de gás natural não convencional na bacia do Paraná: avaliação da viabilidade no abastecimento da usina termoelétrica de Uruguaiana (RS) / A geological study of the potential for exploration and production of shale gas in Paraná sedimentary basin, Brazil: viability evaluation to supply thermoelectricity generation in Uruguaiana power plant.

Rocha, Haline de Vasconcellos 19 February 2016 (has links)
A presente dissertação de mestrado consiste na realização de um estudo geológico acerca do potencial para exploração e produção de gás natural não convencional na Bacia do Paraná, regiões sul e sudeste do Brasil e norte do Uruguai. Com essa finalidade, foram analisadas as formações geológicas Irati e Ponta Grossa, situadas na porção sul da bacia e caracterizadas por seu potencial gerador de hidrocarbonetos. O estudo também inclui a avaliação da viabilidade do abastecimento da usina termoelétrica de Uruguaiana a partir desse recurso, considerando os aspectos geológicos, socioeconômicos e ambientais associados. O projeto visa incentivar o estudo à temática de recursos energéticos não convencionais, com destaque para o shale gas, principal fonte de gás natural não convencional explorada no mundo, além de ressaltar os benefícios na crescente implantação do gás natural na matriz energética brasileira, tanto em aspectos estratégicos quanto econômicos. O projeto propõe a elaboração de um modelo descritivo-comparativo baseado nos aspectos geológicos dos principais campos produtores de shale gas nos Estados Unidos, principal produtor mundial, por meio do qual é avaliado o potencial para ocorrência desse recurso nos folhelhos negros correspondentes às Formações Irati e Ponta Grossa, segundo parâmetros geoquímicos, petrofísicos e geológicos presentes em formações comprovadamente produtoras nos EUA: Marcellus, Barnett e Eagle Ford. O modelo descritivo tem finalidade de avaliar o potencial para exploração, produção e distribuição de gás natural não convencional nas regiões sul e sudeste do Brasil, as quais representam o maior mercado consumidor e demanda por energia no país. Com base na análise comparativa realizada, atribui-se às formações brasileiras potencial moderado a elevado para a geração de shale gas. Entretanto, a viabilidade no abastecimento da usina termoelétrica de Uruguaiana depende, além da geologia local, de fatores político-regulatórios ainda pouco consolidados no país para a incentivar a produção de recursos energéticos não convencionais. / The presented Masters Thesis consists on a geological study of the potential for exploration and production of unconventional natural gas in the Paraná Sedimentary Basin, southern and southeastern Brazil, and northern Uruguay. Therefore, the geological formations Irati and Ponta Grossa, located in the southern portion of the basin, were analyzed in terms of its hydrocarbon generating potential. The study also includes the viability evaluation of this occurrence as a supply for a thermal power plant in Uruguaiana, considering the geological socio-economic and environmental associated aspects. The project aims to promote studies on the topic of unconventional energy resources, especially shale gas, the main unconventional source of natural gas exploited in the world; in addition to emphasizing the advantages in increasing the implement of natural gas into the Brazilian energy matrix, both in strategic and economic aspects. The project proposes the development of a descriptive and comparative model based on geological aspects of the major shale gas producing fields in the United States, the world\'s leading producer; by which we are able to evaluate the potential for occurrence of this resource in the corresponding black shale formations Irati and Ponta Grossa according to geochemical, petrophysical and geological parameters present in these proven producing formations: Marcellus, Barnett and Eagle Ford. The descriptive model was elaborated in order to evaluate the potential for exploration, production and distribution of unconventional natural gas in the southern and southeastern regions of Brazil, which correspond to the largest consumer market and energy demand in the country. Based on a comparative analysis, the Brazilian geological formations are quantified with a moderate to high potential for generating shale gas. However, the viability of using this resource as supply for thermal electricity generation in Uruguaiana depends, in addition to the local geology, to political and regulatory aspects, which are still poorly consolidated among the country, in order to encourage the production of unconventional energy resources.

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