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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.
1

A Mutual Construction of the International System and the Nation States within a Model of Level-of-Analysis¡ÐA Case Study of the September 11 and the War on Terrorism

Wu, Tien-lun 13 December 2004 (has links)
Since the mode of level-of-analysis has to be treated as an empirical tool for IR theories to make a claim to become a social science in its own right, this study attempts to explore the political process of a mutual construction of the international system and the nation states within the model in three parts. Firstly, this study examines how the international system and the national states be settled upon as pregiven scientific entities on the basis of objective spatiality of territory and borders. Secondly, this study shows that in order to merge all states¡¦ diversities and differences into the sameness and likeness, the mutual construction is linked to the plausible assumptions about the structural world of universal rationality among all states, and the unfolding history of linear and progressive evolution. Finally, this study takes the September 11 and the war on terrorism as an example to illustrate the mutual construction and its consequences.
2

Geodesic deviation equation in locally de Sitter spacetimes / Desvio geodésico em espaços localmente de de Sitter

Salazar Malpartida, Johan Renzo 01 August 2018 (has links)
Submitted by Johan Renzo Salazar Malpartida (johanrenzosm@gmail.com) on 2018-09-24T18:20:35Z No. of bitstreams: 1 0-Thesis.pdf: 349725 bytes, checksum: a61b999c76db9b574769428cae02bc08 (MD5) / Rejected by Hellen Sayuri Sato null (hellen@ift.unesp.br), reason: Solicitamos que realize correções na submissão seguindo as orientações abaixo: - Passar na biblioteca para elaborar a ficha catalográfica que deverá ser inserida na dissertação antes de inserir no repositório. A ficha deve consta no PDF - Corrigir o título, pois no pdf o título está em inglês. Portanto, o campo título deve ser preenchido em inglês e o campo titulo alternativo em português - entrada do seu nome deve ser pelo sobrenome do seu pai. - Se o sobrenome do seu pai for Malpartida --> deve ser preenchido Malpartida, Johan Renzo Salazar - Se o sobrenome do seu pai for Salazar --> deve ser preenchido Salazar Malpartida, Johan Renzo - Faltou inserir o abstract - Faltou preencher o campo área de concentração - Faltou preencher o campo Linha de pesquisa on 2018-09-25T17:29:41Z (GMT) / Submitted by Johan Renzo Salazar Malpartida (johanrenzosm@gmail.com) on 2018-09-26T13:20:52Z No. of bitstreams: 2 ficha catalográfica -Johan Renzo Salazar malpartida (1).pdf: 84996 bytes, checksum: 67952920d1945336e50e78b9a7752d7d (MD5) 0-Thesis.pdf: 440560 bytes, checksum: b830fa43b5d20651d6f0b7a1cd7998c9 (MD5) / Rejected by Hellen Sayuri Sato null (hellen@ift.unesp.br), reason: Johan, Conforme orientação que foi dada ontem, a ficha catalográfica precisa ser inserida no pdf da dissertação, logo após a folha de rosto, onde consta o titulo, seu nome, orientador... on 2018-09-26T14:44:32Z (GMT) / Submitted by Johan Renzo Salazar Malpartida (johanrenzosm@gmail.com) on 2018-09-26T15:50:22Z No. of bitstreams: 3 ficha catalográfica -Johan Renzo Salazar malpartida (1).pdf: 84996 bytes, checksum: 67952920d1945336e50e78b9a7752d7d (MD5) 0-Thesis.pdf: 440560 bytes, checksum: b830fa43b5d20651d6f0b7a1cd7998c9 (MD5) 0-Thesis.pdf: 471654 bytes, checksum: 992ba3db7e6190e79618954b961abc5e (MD5) / Rejected by Hellen Sayuri Sato null (hellen@ift.unesp.br), reason: Johan, Por favor, a ficha precisa ser anexada do jeito que foi enviada. A mesma ficou desconfigurada no pdf. Ela tem que ficar centralizada na parte inferior da página, do jeito que foi enviada Favor deletar os arquivos antigo e manter um único arquivo on 2018-09-26T18:16:10Z (GMT) / Submitted by Johan Renzo Salazar Malpartida (johanrenzosm@gmail.com) on 2018-09-26T18:37:13Z No. of bitstreams: 1 0-Thesis-merged.pdf: 573271 bytes, checksum: 37b052e0c5e3b1c119f1f920c0d3eaaa (MD5) / Approved for entry into archive by Hellen Sayuri Sato null (hellen@ift.unesp.br) on 2018-09-27T17:57:19Z (GMT) No. of bitstreams: 1 salazarmalpartida_jr_me_ift.pdf: 573271 bytes, checksum: 37b052e0c5e3b1c119f1f920c0d3eaaa (MD5) / Made available in DSpace on 2018-09-27T17:57:19Z (GMT). No. of bitstreams: 1 salazarmalpartida_jr_me_ift.pdf: 573271 bytes, checksum: 37b052e0c5e3b1c119f1f920c0d3eaaa (MD5) Previous issue date: 2018-08-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Como é bem conhecido, a relatividade especial de Einstein, cuja cinemática é governada pelo grupo de Poincaré, deixa de valer na escala de Planck devido à existência de uma escala de comprimento invariante, dada pelo comprimento de Planck. Por essa razão, ela é incapaz de descrever a cinemática naquela escala. Uma solução possível para esse problema, a qual preserva a simetria de Lorentz — e consequentemente a causalidade — é substituir a relatividade especial de Einstein por uma relatividade especial na qual a cinemática é governada pelo grupo de de Sitter. Claro que uma mudança na relatividade especial irá pruduzir mudanças concomitantes na relatividade geral, a qual se torna o que chamamos de relatividade geral modificada por de Sitter. Trabalhando no contexto dessa teoria, o objetivo desse trabalho é deduzir a fórmula geral da aceleração relativa entre duas geodésicas próximas, a qual leva à equação do desvio geodésico modificada por de Sitter. Uma análise simples dos efeitos adicionais induzidos pela cinemática local de de Sitter é apresentada. / As is well-known, the Poincaré invariant Einstein special relativity breaks down at the Planck scale due to the presence of an invariant length, given by the Planck length. For this reason, it is unable to describe the spacetime kinematics at that scale. A possible solution to this problem that preserves Lorentz symmetry — and consequently causality — is arguably to replace the Poincaré invariant Einstein special relativity by a de Sitter invariant special relativity. Of course, a change in special relativity produces concomitant changes in general relativity, which becomes what we have called de Sitter modified general relativity. By working in the context of this theory, the purpose of this work is to deduce the general relative acceleration between nearby geodesics, which leads to the de Sitter modified geodesic deviation equation. A simple analysis of the additional effects induced by the local de Sitter kinematics is presented. / 33015015001P7
3

Récurrence sur les espaces homogènes / Recurrence on homogeneous spaces

Bruère, Caroline 19 May 2017 (has links)
On choisit un groupe algébrique G, un sous-groupe algébrique H de G ; on choisit une mesure de probabilité borélienne μ sur G. On considère alors la chaîne de Markov sur l’espace homogène X = G/H de probabilité de transition Px = μ * δx pour x ε X. Dans cette thèse, on étudie les propriétés de récurrence de ces marches aléatoires.On s’intéresse à deux types de récurrence : la récurrence presque-sûre (toute trajectoire revient presque-sûrement infiniment souvent dans un compact) et la récurrence en loi (il existe une mesure de probabilité μ stationnaire sur X .On s’intéresse également aux éventuelles propriétés de transience presque-sûre (toute trajectoire quitte presque-sûrement définitivement tout compact).On construira d’abord un exemple où on n’a ni récurrence presque-sûre en tout point, ni transience presque-sûre en tout point. On montrera ensuite un critère de récurrence presque-sûre dans le cas où G est un groupe de Lie semi-simple ; on a en fait dans ce cas une dichotomie : soit tous les points sont récurrents,soit tous les points sont transients.Dans le cas où G est le groupe affine GL(d,ℝ) α ℝd,on donnera un critère de récurrence en loi sur les Grassmanniennes affines, et, dans un dernier chapitre, on donnera quelques résultats partiels d'un projet en cours,permettant de donner des résultats pour le groupe SO(p, p+1) α ℝ2p+1. / Choose an algebraic group G, and an algebraic subgroup H. Choose a Borel probability measure μ on G. Consider the Markov chain on the G-space X = G/H with transition probability Px = μ * δx for x ε X.The point of this dissertation is the study of the recurrence properties of such a random walk.We consider two types of recurrence : almost-certain recurrence (i.e. almost-every trajectory enters some compact set infinitely often) and the associated almost-certain transience (where almost-every trajectory eventually leaves every compact set) and recurrence in law (i.e. there exists a μ stationary probability measure on X).First, we show that, in general, there is no dichotomy between almost-certain recurrence and transience by constructing an example with both almost-certainly recurrent and almost-certainly transient points.We then prove a criterion for almost-certain recurrence when G is a semi-simple Lie group and X is a G-space. In fact, in this case, we have a dichotomy where either every point of X is almost-certainly recurrent, or every point of X is almost certainly transient.When G is the affine group GL(d,ℝ) α ℝd, we give a criterion for recurrence in law on the affine Grassmannians.In the final chapter, we give some partial results from an ongoing project,which give a criterion for recurrence in law the group SO(p,p+1)α ℝ2p+1.
4

Secant varieties of Spinor varieties and of other generalized Grassmannians

Galgano, Vincenzo 18 December 2023 (has links)
Secant varieties are among the main protagonists in tensor decomposition, whose study involves both pure and applied mathematic areas. Despite they have been studied for decades, several aspects of their geometry are still mysterious, among which identifiability and singularity of their points. In this thesis we study the secant varieties of lines of Grassmannians and of Spinor varieties. As first result, we completely determine their posets of orbits under the action of the groups SL and Spin, respectively. Then we solve the problems of identifiability and tangential-identifiability of points in the secant varieties of lines: as a consequence, we also determine the second Terracini locus to a Grassmannian and to a Spinor variety. Our main result concerns the singular locus of the secant variety of lines: we completely determine it for Grassmannians, and we give lower and upper bounds for Spinor varieties. Finally, we partially describe the poset of orbits in the secant variety of lines of any cominuscule variety.
5

Transformações Geométricas no Plano e no Espaço

Silva, Rênad Ferreira da 14 August 2013 (has links)
Submitted by Viviane Lima da Cunha (viviane@biblioteca.ufpb.br) on 2015-05-19T14:20:06Z No. of bitstreams: 2 arquivototal.pdf: 9893623 bytes, checksum: 211bb6b2f2a20721abf5b2948352c518 (MD5) license_rdf: 22190 bytes, checksum: 19e8a2b57ef43c09f4d7071d2153c97d (MD5) / Approved for entry into archive by Maria Suzana Diniz (msuzanad@hotmail.com) on 2015-05-19T14:27:36Z (GMT) No. of bitstreams: 2 arquivototal.pdf: 9893623 bytes, checksum: 211bb6b2f2a20721abf5b2948352c518 (MD5) license_rdf: 22190 bytes, checksum: 19e8a2b57ef43c09f4d7071d2153c97d (MD5) / Made available in DSpace on 2015-05-19T14:27:36Z (GMT). No. of bitstreams: 2 arquivototal.pdf: 9893623 bytes, checksum: 211bb6b2f2a20721abf5b2948352c518 (MD5) license_rdf: 22190 bytes, checksum: 19e8a2b57ef43c09f4d7071d2153c97d (MD5) Previous issue date: 2013-08-14 / Abstract: In this work we study some geometric transformations in the plane and the space. Initially, we present some special types of transformations in the plane and find the matrix of each of these transformations. In the second part we discourse the transformations in the space, emphasizing the rotations. We will use the angles of Euler to determine a rotation in the space around the Cartesian axes and define an equation which allows to rotate a vector around any axis. We also discuss the homogeneous spaces aiming the matrix representation of transformations of translation. Finally, we use the structure of the quaternions group to present a second form to rotation vectors and composition of rotations in the space. We emphasize that this study is essential to describe the motion of objects in the plane and in the space. / Neste trabalho estudamos algumas das transformações geométricas no Plano e no Espaço. Inicialmente, apresentamos alguns tipos de transformações especiais no Plano e encontramos a matriz de cada uma destas transformações. Na segunda parte abordamos as transformações no Espaço, dando ênfase as rotações. Utilizamos os ângulos de Euler para determinar uma rotação no espaço em torno dos eixos cartesianos e definimos uma equação que permite rotacionar um vetores em torno de um eixo qualquer. Também abordamos os espaços homogêneos objetivando a representa ção matricial da transformação de translação. Por último, usamos a estrutura do grupo dos Quatérnios para apresentar uma segunda forma de fazer rotações de vetores e composição de rotações no espaço. Ressaltamos que este estudo é fundamental para descrever o movimento de objetos no plano e no espaço.
6

Déformation et construction de surfaces minimales / Deformation and construction of minimal surfaces

Coutant, Antoine 05 December 2012 (has links)
L'objet de cette thèse consiste en la construction de nouveaux exemples de surfaces (ou hypersurfaces) minimales dans les espaces euclidiens R^3, R^n x R avec n>2 ou dans l'espace homogène S^2 x R. Nous prouvons l'existence de surfaces minimales dans R^3 arbitrairement proches d'un polygone convexe. Nous prouvons également l'existence d'hypersurfaces minimales de type Riemann dans R^n x R, n>2. Celles-ci peuvent être interprétées comme étant une famille d'hyperplans horizontaux (des bouts) reliés les uns aux autres par des morceaux de caténoïdes déformés (des cous). Nous donnons un résultat général pour ce type d'objet quand il est périodique ou bien quand il a un nombre fini de bouts horizontaux. Cela se fait sous certaines hypothèses de contraintes sur les forces intervenant dans la construction. Nous finissons en donnant plusieurs exemples, notamment l'existence d'une hypersurface de type Wei verticale qui n'existe pas en dimension 3. Nous donnons aussi la preuve de l'existence d'une surface minimale de type Riemann dans S^2 x R telle que deux bouts sphériques sont reliés entre eux alternativement par 1 cou et 2 cous. Là aussi, nous mettons en évidence le rôle joué par les forces lors de la construction. De même que dans le chapitre précédent, la méthode repose sur un processus de recollement. Nous donnons une description très précise de la caténoïde et la surface de Riemann dans S^2 x R. Enfin, nous établissons l'existence dans R^n x R d'hypersurfaces de type Scherk lorsque n>2 / This thesis is devoted to the construction of numerous examples of minimal surfaces (or hypersurfaces) in the $3$-Euclidean space, R^n x R with n>2 or in the homogeneous space S^2 x R . We prove the existence of minimal surfaces in R^3 as close as we want of a convex polygon. We prove the existence of minimal hypersurfaces in R^n x R, n>2, whose have Riemann's type. These ones could be considered as a family of horizontal hyperplanes (the ends) which are linked to each other by pieces of deformed catenoids (the necks). We provide a general result in the case simply-periodic together with the case of a finite number of hyperplanar ends. Our construction lies on some conditions associates with the forces that characterize the different configurations. We end with giving some examples ; in particular, we exhibit the existence of vertical Wei example that does not exists in the 3-dimensional case. We also prove the existence of the analogous of the Wei example in S^2 x R. The surface is such that two spherical ends are linked by 1 neck and 2 necks alternatively. Here again, we highlight the role that the forces play in the construction. Moreover, like in the previous chapter, the method lies on a gluing process. We give an accurate description of the catenoid and the Riemann's minimal example in S^2 x R. Finally, we demonstrate the existence of Scherk type hypersurfaces in R^n x R when n>2
7

Uniformisation des variétés pseudo-riemanniennes localement homogènes / Uniformization of pseudo-riemannian locally homogeneous manifolds

Tholozan, Nicolas 04 November 2014 (has links)
Ce travail étudie les variétés pseudo-riemanniennes compactes localement homogènes à travers le prisme des (G,X)-structures, introduites par Thurston dans son programme de géométrisation. Nous commençons par présenter la problématique générale et discutons notamment du rapport entre la complétude géodésique de ces variétés et une autre notion de complétude propre aux (G,X)-structures. Nous donnons également dans le chapitre 1 une nouvelle preuve d’un théorème de Bromberg et Medina qui classifie les métriques lorentziennes invariantes à gauche sur SL(2,R) dont le flot géodésique est complet. Conjecturalement, toute (G,X)-structure pseudo-riemannienne sur une variété compacte est complète. Nous prouvons ici que cela est vrai pour certaines géométries, sous l’hypothèse que la (G,X)-structure est a priori kleinienne. On en déduit que, pour ces géométries, la complétude est une condition fermée. Lorsque X est un groupe de Lie de rang 1 muni de sa métrique de Killing, ce résultat complète un théorème de Guéritaud–Guichard–Kassel–Wienhard selon lequel la complétude est une condition ouverte. Nous nous tournons ensuite vers l’étude des représentations d’un groupe de surface à valeurs dans les isométries d’une variété riemannienne M complète simplement connexe de courbure sectionnelle inférieure à -1. Étant donnée une telle représentation ρ, nous montrons que l’ensemble des représentations fuchsiennes j telles qu’il existe une application (j,ρ)-équivariante et contractante de H2 dans M est un ouvert non vide et contractile de l’espace de Teichmüller (sauf lorsque ρ est elle-même fuchsienne). Ce résultat nous permet de décrire l’espace des métriques lorentziennes de courbure constante -1 sur un fibré en cercle au-dessus d’une surface compacte. Nous montrons que cet espace possède un nombre fini de composantes connexes classifiées par un invariant que nous appelons longueur de la fibre. Nous prouvons également que le volume total de ces métriques ne dépend que de la topologie du fibré et de la longueur de la fibre. / In this work, we study closed locally homogeneous pseudo-Riemannian manifolds through the notion of (G,X)-structure, introduced by Thurston in his geometrization program. We start by presenting the general problem. In particular, we discuss the link between geodesical completeness of those manifolds and another notion of completeness specific to (G,X)-structures. In chapter 1, we also give a new proof of a theorem by Bromberg and Medina which classifies left invariant Lorentz metrics on SL(2,R) that are geodesically complete. Conjecturally, every pseudo-riemannian (G,X)-structure on a closed manifold is complete. Here we prove that it holds for certain geometries, provided that the (G,X )-structure is a priori Kleinian . This implies that, for such geometries, completeness is a closed condition. When X is a Lie group of rank 1 handled with its Killing metric, this result complements a theorem of Guéritaud–Guichard–Kassel–Wienhard, acording to which completeness is an open condition. We then turn to the study of representations of surface groups into the isometry group of a complete simply connected Riemannian manifold M of curvature less than or equal to -1. Given such a representation ρ, we prove that the set of Fuchsian representations j for which there exists a (j,ρ)-equivariant contracting map from H2 to M is a non-empty open contractible subset of the Teichmüller space (unless ρ itself is Fuchsian). This result allows us to describe the space of Lorentz metrics of constant curvature -1 on a circle bundle over a closed surface. We show that this space has finitely many connected components, classified by an invariant that we call the length of the fiber. We also prove that the total volume of those metrics only depends on the topology of the bundle and on the length of the fiber.
8

Principe local-global pour les zéro-cycles / Local-global principle for zero-cycles

Liang, Yongqi 04 October 2011 (has links)
Dans cette thèse, nous nous intéressons à l’étude de l’arithmétique (le principe de Hasse, l’approximation faible, et l’obstruction de Brauer-Manin) des zéro-cycles sur les variétés algébriques définies sur des corps de nombres. Nous introduisons la notion de sous-ensemble hilbertien généralisé. En utilisant la méthode de fibration, nous démontrons que l’obstruction de Brauer-Manin est la seule au principe de Hasse et à l’approximation faible pour les zéro-cycles de degré 1; et établissons l’exactitude d’une suite de type global-local concernant les groupes de Chow des zéro-cycles, pour certaines variétés qui admettent une structure de fibration au-dessus d’une courbe lisse ou au-dessus de l’espace projectif, où les hypothèses arithmétiques sont posées seulement sur les fibres au-dessus d’un sous-ensemble hilbertien généralisé.De plus, nous relions l’arithmétique des points rationnels et l’arithmétique des zérocycles de degré 1 sur les variétés géométriquement rationnellement connexes. Comme application, nous trouvons que l’obstruction de Brauer-Manin est la seule au principe de Hasse et à l’approximation faible pour les zéro-cycles de degré 1 sur- les espaces homogènes d’un groupe algébrique linéaire à stabilisateur connexe,- certains fibrés en surfaces de Châtelet au-dessus d’une courbe lisse ou au-dessus de l’espace projectif (en particulier, les solides de Poonen). / This Ph. D. thesis studies the arithmetic properties (the Hasse principle, the weak approximation, and the Brauer-Manin obstruction) for zero-cycles on algebraic varieties defined over number fields. We introduce the notion of generalized Hilbertian subset. By using the fibration method, we prove that the Brauer-Manin obstruction is the only obstruction tothe Hasse principle and to the weak approximation for zero-cycles of degree 1; and establish the exactness of a sequence of global-local type concerning Chow groups of zero-cycles, for certain varieties which admit a fibration structure overa smooth curve or over the projective space, where the arithmetic hypotheses are only posed on the fibers over a generalized Hilbertian subset. Moreover, we relate the arithmetic of rational points and that of zero-cycles of degree 1 on geometrically rationally connected varieties. As an application, we find that the Brauer-Manin obstruction is the only obstruction to the Hasse principle and to the weak approximation for zero-cycles of degree 1 on- homogeneous spaces of a linear algebraic group with connected stabilizer,- certain varieties fibered into Chatelet surfaces over a smooth curve or over the projective space (in particular, Poonen's threefolds).

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