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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.
121

Argumentace v přesvědčeních a praktikách učitelů matematiky v kontextu České republiky / Argumentation in mathematics teachers' beliefs and practices in the context of the Czech Republic

Žalská, Jana January 2018 (has links)
I aim to describe how teachers' beliefs and practices influence the way mathematical argumentation is conducted in lower secondary mathematics classroom within the Czech curricular context. I present results of two studies: the first one characterises the Czech curricular context, namely, the national curricular document and aspects of justification of mathematical statements in selected series of mathematics textbooks. The second study reports on characteristics of teachers' beliefs and practices as related to argumentation on an example of six purposefully selected teachers, via interviews and observations of their lessons. Finally, I select three teachers with differing approaches to teaching and describe specific observed instances in their practices in relation to classroom norms regarding argumentation, justification of general mathematical truths, and aspects of arguments. I show how teachers' beliefs, a textbook and pupils may influence the observed arguments. The studies show that a teachers' emphasis on efficiency (fulfilling school curriculum demands) on one hand and on sense-making on the other lead to distinct implemented curricula. The curricular context and teachers' practice analysis suggest that justification of general truths is generally seen as important but without clear cognitive aims...
122

Idé och verklighet : En komparativ studie av det ontologiskagudsbeviset hos S:t Anselm av Canterbury ochRené Descartes / Idea and Reality : A Comparative Study of the OntologicalArgument of St. Anselm of Canterbury andRené Descartes

Forss, Elin January 2022 (has links)
This essay consists of a comparative study of the ontological argument for the existence of God asformulated by St. Anselm of Canterbury and René Descartes. The comparative analysis itselfconsists of two parts. Firstly, a comparative study of the argument itself, and an examination of theunderlying metaontological commitments that form the basis of the respective arguments, whichare then likewise contrasted. The stated purpose is to examine whether two versions of theontological argument that appear to be similar may have an underlying framework that makes themfundamentally fundamentally distinct in a way that is not immediately apparent. The analysis foundthat this was the case, and that there are significant differences in how the argument is formulated.This is of interest especially as these two thinkers wrote in and were influenced by widely differingcultural, intellectual and academic contexts, which may be reflected in their work. Ontologicalarguments for the existence of God as a phenomenon is a metaphysical argument that seeks toprove that God exists without relying on empirical and observational evidence. Rather, one seeksthrough these ontological arguments to show that the existence of God is self-evident.With Anselm and Descartes this happens in a seemingly very similar yet fundamentally differentway. The results of this study demonstrate differences that appear primarily in the starting point forthe respective discourses, as well as in the methodology that is applied. Anselm bases his discourseon a distinctly neoplatonic foundation regarding the highest good, which he later extrapolates to amore comprehensive reasoning regarding the distinction between different natures according togreatness, of which goodness is one such greatness. Descartes, on the other hand, anchors hisdiscourse in scholastic philosophy and especially the idea of the causal principle of transference,especially in relation to human consciousness and the idea or the concept of God which manifeststherein. These results have been achieved primarily by examining Anselm's arguments based onsecondary sources that relate both directly and indirectly to his ontological argument, which in itssimplicity otherwise consists almost in its entirely of a self-evident descriptive definition of whatGod is. However, the differences that emerge are not of such a degree that a division of these twoargument into different categories can be made with a high degree of confidence. On the otherhand, it is of interest to analyze these underlying frameworks for ontological arguments in order toalso be able to analyze the potential influence or impact of various contextual aspects such as place,time and prevailing academic culture as this essay attempts to do.
123

Havsbaserad vindkraft i svensk media : En kvalitativ studie om konflikter och argument (för och emot) gällande havsbaserad vindkraft i Sverige

Bäcklund, William January 2023 (has links)
The aim with this study is to analyze and try to understand the arguments and conflicts associated with the planning and development of offshore wind power in Sweden, and to study various media articles and their significance for offshore wind power in Sweden. A qualitative method has been applied in the form of a media analysis. The material for the study is based on diverse types of articles from the media in the form of news articles, commentaries, and debate articles. The articles I have chosen to analyze come mostly from the most popular news editors in Sweden; "Aftonbladet", "Dagens Nyheter" and "Svenska Dagbladet". There are also news articles from local newspapers so that even smaller local events can be captured and studied. Further in this study, media such as Swedish Radio and SVT Nyheter have been applied where shorter news items can be examined. This result shows how the opposition and arguments for and against offshore wind power are played out in the media and that the media can function as an information provider for offshore wind power linked to the planning and expansion of offshore wind power in Sweden. Many opinions want to highlight the negative consequences of offshore wind power, mainly from a local point of view. In some cases, opposition is also about preserving nature's values and not making interventions in nature that affect biodiversity, but this is something that "NIMBY" may have led to. That media coverage of the topic is largely based on informing people about ongoing projects and preparing press releases with important information about the projects, as well as acting as an information channel.
124

Filosofiska frågor i det naturvetenskapliga klassrummet : Verktyg för tänkande / Philosophical questions in the science classroom : A tool for thinking

Svensson, Robert January 2022 (has links)
Syftet med denna kvalitativa studie har varit att utveckla kunskaper om hur filosofiska frågor i det naturvetenskapliga klassrummet påverkar elevers kommunikativa förmåga att argumentera och ta ställning. Frågeställningarna som använts för att möjliggöra studien är: På vilka sätt argumenterar elever i mötet med filosofiska frågor av naturvetenskaplig karaktär? Hur kan filosofiska frågor användas som resurs i det naturvetenskapliga klassrummet för att gynna elevers kommunikativa förmåga att argumentera och ta ställning inom naturvetenskap? Studien genomfördes vid en skola i norra Sverige och bestod av 13 deltagare från årskurserna 3-6 som deltog vid fyra undervisningstillfällen. Undervisningstillfällena bestod av utredning av filosofiska frågor med naturvetenskaplig karaktär i samtalsgrupper där en filosofisk samtalsstruktur följdes. Tillfällena observerades och data samlades in med hjälp av video– och ljudinspelning samt loggboksanteckningar. Resultatet visade att eleverna argumenterade utifrån följande kategorier i mötet med lektionsinnehållet: Nyttoargument, etiska argument, estetiska argument, hållbarhetsargument och relevansargument. Vidare visade studiens resultat att faktorer som struktur, lärarstöd, elevstöd och metaforer var viktiga för eleverna i mötet med filosofiska frågor av naturvetenskaplig karaktär. Sammanfattningsvis visade denna studie att elevernas argumentationer och ställningstagande kan påverkas i positiv bemärkelse vid arbete med filosofiska frågor av naturvetenskaplig karaktär. / The purpose of this qualitative study was to develop knowledge about how philosophical questions in the science classroom affects students' communicative ability to argue and to take positioning in a dilemma. The issues this study used to enable the study was: In what ways do students argue in the encounter with philosophical questions of a scientific nature? How can philosophical questions be used as a resource in the science classroom to benefit students' communicative ability to argue and take positioning in science? The study was implemented at a school in northern Sweden and consisted of 13 participants from the grades 3-6 who participated in four teaching opportunities. The teaching opportunities consisted of a philosophical inquiry of science questions in conversation groups where a philosophical conversation structure was followed. The teaching opportunities were observed and data was collected with the aid of video– and sound recording and logbook notes. Results show that students argued from the following categories: Utility argument, ethical arguments, aesthetic arguments, sustain arguments and relevance arguments. The result further showed that factors like: structure, teacher support, student support and metaphors were of importance to the students in their meeting with philosophical questions of a scientific nature. In summary, this study showed that students' arguments and positioning can be affected in positive meaning by using philosophical questions with scientific nature.
125

Fokus på hållbarhet? : En analys av kulturmiljövårdens miljömässiga hållbarhetsarbete analyserat enligt Kulturvård 3.0 / Focus on sustainability? : The environmental dimension of cultural heritage management analysed through Kulturvård 3.0

Hallstensson, Andréa January 2022 (has links)
Uppsatsen har två tydliga utgångspunkter. Den ena lyfter fram Agenda 2030 som en gemensam målbild för det hållbarhetsarbete som behöver ske för att uppnå ett socialt, ekonomiskt och miljömässigt hållbart samhälle inom överskådlig framtid. Den andra är det självklara i att: när kulturmiljövårdssektorn argumenterar för att det byggda kulturarvet bör bevaras så innebär det även, per definition, en möjlighet till resurshushållning av ändliga materiella resurser. Uppsatsen belyser frågor kring hur konsulter inom den svenska kulturmiljövården ställer sig till att använda miljömässiga hållbarhetsargument i relation till uppdragsgivare och myndigheter. Frågan ställs huruvida det ingår i kulturmiljövårdens roll att argumentera för hushållandet av ändliga materiella resurser jämte bevarandet av kulturvärden? Intervjuer har genomförts med 18 representanter från kulturmiljövården, dess uppdragsgivare och beställare samt Stockholms Statsbyggnadskontor. Sammanfattningsvis visar undersökningen att respondenterna anser att kulturmiljövårdssektorn idag inte använder sig av miljömässiga argument för att lyfta fram hushållandet av ändliga materiella resurser. En majoritet av respondenterna ställer sig positiva till att sektorn skulle kunna göra det i framtiden. Attityder kring livscykelanalyser baserade på generisk data har undersökts som ett möjligt verktyg för att synliggöra och kvantifiera eventuella miljömässiga vinster i samband med bevarande av det byggda kulturarvet. Detta som ett exempel på ett konkret miljömässigt argument. 17 av 18 respondenter i undersökningen anser att det vore användbart, dock utifrån olika perspektiv. Vidare pekar intervjusvaren på att det råder delade meningar kring vilken roll kulturmiljövården ska ha inom hållbar samhällsbyggnad, och om miljömässiga argument bör innefattas i den rollen. Intervjusvaren sätts in i en bredare kontext via analysen som tar avstamp i tankemodellen Kulturvård 3.0. Här definieras tre faser inom vilka kulturmiljövården verkar. Dessa kan sammanfattas som: fas 1.0 där fokus ligger på att bevara och skydda byggnader, 2.0 där fokus ligger på att vårda och restaurera byggnader, 3.0 där fokus ligger på att använda byggnader på ett sätt som kan bidra till hållbar utveckling. Enligt analysen ligger uppsatsens frågeställningar fortfarande inom pågående förhandling kring vad som bör ingå i kulturmiljövårdens framtida roll. Förhandlingen kan i sin tur ses som en del av fas 3 i tankemodellen, där teman som hållbar utvekling, anpassad återanvändning, kulturmiljövården som resurs samt samarbete över sektorsgränser, står som riktmärken.
126

Motivation Matters: A Critical Analysis and Refutation of Evolutionary Arguments for Psychological Altruism

Curry, Fred Foster 27 March 2007 (has links)
No description available.
127

O Fórum Gaúcho de Saúde Mental e os argumentos sobre a reforma psiquiátrica no Rio Grande do Sul : relações sociais e princípios de justificação

Russczyk, Jaqueline January 2008 (has links)
Ce mémoire est a comme sujet les arguments produits dans les litiges qui impliquent les conceptions sur la santé mentale, présente dans les justifications et les actions des acteurs sociaux impliqués dans les discussions relatives à la maladie mentale au Rio Grande de Sul, dans un contexte de Contre-Réforme Psychiatrique. Cette étude vise à déterminer si c'est à partir de certaines relations sociales parmi les acteurs sociaux que les justifications et les actions sont produites. L'objet de cette étude est composé par les relations sociales et les arguments produits par les membres du Forum Gaucho de Santé Mentale à Porto Alegre. On utilise l’analyse relationnelle ainsi que la référence théorique de Michel Foucault et la sociologie pragmatique de Luc Boltanski. Il a été constaté qu’à partir d’une mise en cause sur la manière dont la configuration du Forum Gaucho de la Santé Mentale se concentre sur les principes de la justification employée par les acteurs sociaux appartenant au groupe, qu'il y a des idées différentes sur la santé mentale au sein du Forum et qu’il existe une prévalence de certains principes de la justification dans le discours une fois qu’il y a une prévalence de certains acteurs sociaux qui dépeint le discours. Pour bien mener cette investigation, dix représentants du Forum Gaucho de la santé mentale à Porto Alegre ont été interviewés et on a utilisé comme procédure méthodologique l'observation, ainsi que l'interview avec l'utilisation d'un script écrit. Après l'achèvement des entretiens, on a fait l'analyse de contenu. / Esta dissertação tem como tema os argumentos produzidos nas disputas envolvendo as concepções sobre saúde mental, presentes nas justificações e ações dos atores sociais envolvidos nas discussões referentes à Reforma Psiquiátrica, no Rio Grande de Sul, em um contexto de Contra-Reforma Psiquiátrica. O presente estudo tem como finalidade verificar se é a partir de determinadas relações sociais entre os atores sociais que as justificações e as ações são produzidas. O objeto deste estudo são as relações sociais e os argumentos produzidos pelos integrantes do Fórum Gaúcho de Saúde Mental de Porto Alegre. Utiliza-se a análise relacional, bem como o referencial teórico de Michel Foucault e a sociologia pragmática de Luc Boltanski. Foi verificado, a partir do questionamento de como a configuração do Fórum Gaúcho de Saúde Mental incide sobre os princípios de justificação mobilizados pelos atores sociais pertencentes ao grupo, que há concepções diferenciadas sobre saúde mental dentro do Fórum e há a prevalência de determinados princípios de justificação no discurso porque há uma prevalência de determinados atores sociais que veiculam este discurso. Para a realização desta pesquisa, foram entrevistados dez representantes do Fórum Gaúcho de Saúde Mental de Porto Alegre e utilizou-se como procedimento metodológico a observação, bem como a entrevista com o uso de um roteiro escrito. Após a realização das entrevistas, efetuou-se a análise de conteúdo. / The subject of this thesis is composed by the arguments produced in disputes involving conceptions about mental health present in the justifications and actions of social actors involved in discussions relating to Psychiatry Reformation in Rio Grande de Sul, in a context of Psychiatry Counter-Reformation. This study aims to check whether it is from certain social relations among the social actors that justifications and actions are produced. The object of this study is composed by the social relations and the arguments produced by members of the Forum Gaucho of Mental Health in Porto Alegre. It is used the relational analysis as weel as the theoretical reference to Michel Foucault and to the Luc Boltanski’s pragmatic sociology. It was found from the question of how the configuration of the Forum Gaucho of Mental Health focuses on the principles of justification employed by social actors belonging to the group, that there are different ideas about mental health within the Forum and there is the prevalence of certain principles of justification in the speech because there is a prevalence of certain social actors who portrayed the speech. To carry out this survey, ten representatives of the Forum Gaucho of Mental Health in Porto Alegre were interviewed and it was used as a methodological procedure the observation, as well as the interview using a script writing. After the nterview completion, it was the analysis of content.
128

O Fórum Gaúcho de Saúde Mental e os argumentos sobre a reforma psiquiátrica no Rio Grande do Sul : relações sociais e princípios de justificação

Russczyk, Jaqueline January 2008 (has links)
Ce mémoire est a comme sujet les arguments produits dans les litiges qui impliquent les conceptions sur la santé mentale, présente dans les justifications et les actions des acteurs sociaux impliqués dans les discussions relatives à la maladie mentale au Rio Grande de Sul, dans un contexte de Contre-Réforme Psychiatrique. Cette étude vise à déterminer si c'est à partir de certaines relations sociales parmi les acteurs sociaux que les justifications et les actions sont produites. L'objet de cette étude est composé par les relations sociales et les arguments produits par les membres du Forum Gaucho de Santé Mentale à Porto Alegre. On utilise l’analyse relationnelle ainsi que la référence théorique de Michel Foucault et la sociologie pragmatique de Luc Boltanski. Il a été constaté qu’à partir d’une mise en cause sur la manière dont la configuration du Forum Gaucho de la Santé Mentale se concentre sur les principes de la justification employée par les acteurs sociaux appartenant au groupe, qu'il y a des idées différentes sur la santé mentale au sein du Forum et qu’il existe une prévalence de certains principes de la justification dans le discours une fois qu’il y a une prévalence de certains acteurs sociaux qui dépeint le discours. Pour bien mener cette investigation, dix représentants du Forum Gaucho de la santé mentale à Porto Alegre ont été interviewés et on a utilisé comme procédure méthodologique l'observation, ainsi que l'interview avec l'utilisation d'un script écrit. Après l'achèvement des entretiens, on a fait l'analyse de contenu. / Esta dissertação tem como tema os argumentos produzidos nas disputas envolvendo as concepções sobre saúde mental, presentes nas justificações e ações dos atores sociais envolvidos nas discussões referentes à Reforma Psiquiátrica, no Rio Grande de Sul, em um contexto de Contra-Reforma Psiquiátrica. O presente estudo tem como finalidade verificar se é a partir de determinadas relações sociais entre os atores sociais que as justificações e as ações são produzidas. O objeto deste estudo são as relações sociais e os argumentos produzidos pelos integrantes do Fórum Gaúcho de Saúde Mental de Porto Alegre. Utiliza-se a análise relacional, bem como o referencial teórico de Michel Foucault e a sociologia pragmática de Luc Boltanski. Foi verificado, a partir do questionamento de como a configuração do Fórum Gaúcho de Saúde Mental incide sobre os princípios de justificação mobilizados pelos atores sociais pertencentes ao grupo, que há concepções diferenciadas sobre saúde mental dentro do Fórum e há a prevalência de determinados princípios de justificação no discurso porque há uma prevalência de determinados atores sociais que veiculam este discurso. Para a realização desta pesquisa, foram entrevistados dez representantes do Fórum Gaúcho de Saúde Mental de Porto Alegre e utilizou-se como procedimento metodológico a observação, bem como a entrevista com o uso de um roteiro escrito. Após a realização das entrevistas, efetuou-se a análise de conteúdo. / The subject of this thesis is composed by the arguments produced in disputes involving conceptions about mental health present in the justifications and actions of social actors involved in discussions relating to Psychiatry Reformation in Rio Grande de Sul, in a context of Psychiatry Counter-Reformation. This study aims to check whether it is from certain social relations among the social actors that justifications and actions are produced. The object of this study is composed by the social relations and the arguments produced by members of the Forum Gaucho of Mental Health in Porto Alegre. It is used the relational analysis as weel as the theoretical reference to Michel Foucault and to the Luc Boltanski’s pragmatic sociology. It was found from the question of how the configuration of the Forum Gaucho of Mental Health focuses on the principles of justification employed by social actors belonging to the group, that there are different ideas about mental health within the Forum and there is the prevalence of certain principles of justification in the speech because there is a prevalence of certain social actors who portrayed the speech. To carry out this survey, ten representatives of the Forum Gaucho of Mental Health in Porto Alegre were interviewed and it was used as a methodological procedure the observation, as well as the interview using a script writing. After the nterview completion, it was the analysis of content.
129

O Fórum Gaúcho de Saúde Mental e os argumentos sobre a reforma psiquiátrica no Rio Grande do Sul : relações sociais e princípios de justificação

Russczyk, Jaqueline January 2008 (has links)
Ce mémoire est a comme sujet les arguments produits dans les litiges qui impliquent les conceptions sur la santé mentale, présente dans les justifications et les actions des acteurs sociaux impliqués dans les discussions relatives à la maladie mentale au Rio Grande de Sul, dans un contexte de Contre-Réforme Psychiatrique. Cette étude vise à déterminer si c'est à partir de certaines relations sociales parmi les acteurs sociaux que les justifications et les actions sont produites. L'objet de cette étude est composé par les relations sociales et les arguments produits par les membres du Forum Gaucho de Santé Mentale à Porto Alegre. On utilise l’analyse relationnelle ainsi que la référence théorique de Michel Foucault et la sociologie pragmatique de Luc Boltanski. Il a été constaté qu’à partir d’une mise en cause sur la manière dont la configuration du Forum Gaucho de la Santé Mentale se concentre sur les principes de la justification employée par les acteurs sociaux appartenant au groupe, qu'il y a des idées différentes sur la santé mentale au sein du Forum et qu’il existe une prévalence de certains principes de la justification dans le discours une fois qu’il y a une prévalence de certains acteurs sociaux qui dépeint le discours. Pour bien mener cette investigation, dix représentants du Forum Gaucho de la santé mentale à Porto Alegre ont été interviewés et on a utilisé comme procédure méthodologique l'observation, ainsi que l'interview avec l'utilisation d'un script écrit. Après l'achèvement des entretiens, on a fait l'analyse de contenu. / Esta dissertação tem como tema os argumentos produzidos nas disputas envolvendo as concepções sobre saúde mental, presentes nas justificações e ações dos atores sociais envolvidos nas discussões referentes à Reforma Psiquiátrica, no Rio Grande de Sul, em um contexto de Contra-Reforma Psiquiátrica. O presente estudo tem como finalidade verificar se é a partir de determinadas relações sociais entre os atores sociais que as justificações e as ações são produzidas. O objeto deste estudo são as relações sociais e os argumentos produzidos pelos integrantes do Fórum Gaúcho de Saúde Mental de Porto Alegre. Utiliza-se a análise relacional, bem como o referencial teórico de Michel Foucault e a sociologia pragmática de Luc Boltanski. Foi verificado, a partir do questionamento de como a configuração do Fórum Gaúcho de Saúde Mental incide sobre os princípios de justificação mobilizados pelos atores sociais pertencentes ao grupo, que há concepções diferenciadas sobre saúde mental dentro do Fórum e há a prevalência de determinados princípios de justificação no discurso porque há uma prevalência de determinados atores sociais que veiculam este discurso. Para a realização desta pesquisa, foram entrevistados dez representantes do Fórum Gaúcho de Saúde Mental de Porto Alegre e utilizou-se como procedimento metodológico a observação, bem como a entrevista com o uso de um roteiro escrito. Após a realização das entrevistas, efetuou-se a análise de conteúdo. / The subject of this thesis is composed by the arguments produced in disputes involving conceptions about mental health present in the justifications and actions of social actors involved in discussions relating to Psychiatry Reformation in Rio Grande de Sul, in a context of Psychiatry Counter-Reformation. This study aims to check whether it is from certain social relations among the social actors that justifications and actions are produced. The object of this study is composed by the social relations and the arguments produced by members of the Forum Gaucho of Mental Health in Porto Alegre. It is used the relational analysis as weel as the theoretical reference to Michel Foucault and to the Luc Boltanski’s pragmatic sociology. It was found from the question of how the configuration of the Forum Gaucho of Mental Health focuses on the principles of justification employed by social actors belonging to the group, that there are different ideas about mental health within the Forum and there is the prevalence of certain principles of justification in the speech because there is a prevalence of certain social actors who portrayed the speech. To carry out this survey, ten representatives of the Forum Gaucho of Mental Health in Porto Alegre were interviewed and it was used as a methodological procedure the observation, as well as the interview using a script writing. After the nterview completion, it was the analysis of content.
130

Existence non existence et multiplicité d'ondes stationnaires normalisées pour quelques équations non linéaires elliptiques / Existence, non existence et multiplicité d'ondes stationnaires normalisées pour quelques équations non linéaires elliptiquesExistence, non-existence and multiplicity of normalized standing waves for some nonlinear elliptic equations

Luo, Tingjian 18 December 2013 (has links)
Dans cette thèse, nous étudions l’existence, non existence et multiplicité des ondes stationnairesavec les normes prescrites pour deux types d’équations aux dérivées partiellesnon linéaires elliptiques découlant de différents modèles physiques. La stabilité orbitale desondes stationnaires est également étudiée dans certains cas. Les principales méthodes denos preuves sont des arguments variationnels. Les solutions sont obtenues comme pointscritiques de fonctionnelle associée sur une contrainte.La thèse se compose de sept chapitres. Le Chapitre 1 est l’introduction de la thèse. Dansles Chapitres 2 à 4, nous étudions une classe d’équations de Schrödinger-Poisson-Slaternon linéaires. Nous établissons dans le Chapitre 2 des résultats optimaux non existencede solutions d’énergie minimale ayant une norme L2 prescrite. Dans le Chapitre 3, nousmontrons un résultat d’existence de solutions L2 normalisées, dans une cas où la fonctionnelleassociée n’est pas bornée inférieurement sur la contrainte. Nos solutions sonttrouvées comme des points de selle de la fonctionnelle, mais ils correspondent à des solutionsd’énergée minimale. Nous montrons également que les ondes stationnaires associéessont orbitalement instables. Ici, puisque nos points critiques présumés ne sont pas desminimiseurs globaux, il n’est pas possible d’utiliser de façon systématique les méthodesde compacité par concentration développées par P. L. Lions. Ensuite, dans le Chapitre4, nous montrons que sous les hypothèses du Chapitre 3, il existe une infinité de solutionsayant une norme L2 prescrite. Dans les deux chapitres suivants, nous étudions uneclasse d’équations de Schrödinger quasi-linéaires. Des résultats optimaux non existence desolutions d’énergie minimale sont donnés dans le Chapitre 5. Dans le Chapitre 6, nousprouvons l’existence de deux solutions positives ayant une norme donnée. L’une d’elles,relativement à la contrainte L2, est de type point selle. L’autre est un minimum, soit localou global. Le fait que la fonctionnelle naturelle associée à cette équation n’est pas biendéfinie nécessite l’utilisation d’une méthode de perturbation pour obtenir ces deux pointscritiques. Enfin, au Chapitre 7, nous mentionnons quelques questions que cette thèse asoulevées. / In this thesis, we study the existence, non-existence and multiplicity of standing waves withprescribed norms for two types of nonlinear elliptic partial differential equations arisingfrom various physical models. The orbital stability of the standing waves is also discussedin some cases. The main ingredients of our proofs are variational arguments. The solutionsare found as critical points of an associated functional on a constraint.The thesis consists of seven chapters. Chapter 1 is the Introduction of the thesis.In Chapters 2 to 4, we study a class of nonlinear Schrödinger-Poisson-Slater equations.We establish in Chapter 2 sharp non-existence results of least energy solutions having aprescribed L2-norm. In Chapter 3 we prove an existence result for L2-normalized solutions,in a situation where the associated functional is unbounded from below on the constraint.Our solutions are found as saddle points of the functional but they correspond to leastenergy solutions. We also prove that the associated standing waves are orbitally unstable.Here a key feature is that, since our suspected critical points are not global minimizers, itis not possible to use in a standard way the machinery of compactness by concentrationdeveloped by P. L. Lions. Then, in Chapter 4, we prove that under the assumptions ofChapter 3, there do exist infinitely many solutions having a prescribed L2-norm. In thefollowing two chapters, we investigate a class of quasi-linear Schrödinger equations. Sharpnon-existence results of least energy solutions are given in Chapter 5. In Chapter 6 weprove the existence of two positive solutions having a given norm. One of them, is relativeto the L2-norm constraint, of saddle point type. The other one is a minimum, either localor global. The fact that the natural functional associated with this equation is not welldefined requires the use of a perturbation approach to obtain these two critical points.Finally, in Chapter 7 we mention some questions that this thesis has raised.

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