GERALDO, A. Propriedades de Jordan em anéis de grupo. 2019. Dissertação (Mestrado) - Insti- tuto de Matemática e Estatística, Universidade de São Paulo, São Paulo, 2019. Neste trabalho estudamos alguns resultados a respeito do conjunto dos elementos que são simétricos sobre uma involução, orientada ou não, de um anel de grupo. Dado um anel de grupo RG, onde R é comutativo e com elemento identidade 1, e uma involução orientada # ; apre- sentamos as condições necessárias e suficientes sobre R e G para que o subconjunto (RG) + = { RG # = } seja anticomutativo, ou equivalentemente, o produto de Jordan seja trivial em (RG) + . Além disso, estudamos um caso de nilpotência de Jordan no anel de grupo RG e no seu subconjunto (RG) + , para o caso onde a involução não possui orientação. / In this work we study some results regarding the set of elements that are symmetrical about an involution, oriented or not, in a group ring. Given a group ring RG, where R is commutative and with identity element 1, and an oriented involution # we present the necessary and sufficient conditions on R and G so that the set (RG) + = { RG # = } is anticomutative, or equivalently, the Jordan product is trivial in (RG) + . In addition we study a case of Jordans nilpotency in the group RG and its subset (RG) + , for the case where involution has no orientation.

Countries in southern Africa have been implementing economic liberalisation policies for over two decades, with the aim of reversing years of economic decline. This process of economic liberalisation has been largely been influenced by the International Monetary Fund (IMF) and the World Bank policy prescription. While the developed world has been piling pressure on countries in the Sub-Saharan region to integrate their national economies into the global economic, different countries have responded differently in opening up their economies. For some, the new economic policy regime has entailed a shift from a state-run economy and focusing more on a free market economy. While some countries have taken a cautious approaching to economic liberalisation, Zambia went for rapid liberalisation, which has led to negative social consequences on employment and the livelihoods of the working class. Through the adoption and implementation of labour market flexibility policies, Zambia and other countries in the region have seen an upswing in new forms of employment such as casual labour, subcontracting and temporary employment, which have no protection and have exposed workers to exploitation. Employment levels have also dropped as the capitalist investors shed off massive numbers of workers in order to reduce labour costs. Local manufacturing industries, in most cases, have been forced to close down and lay-off workers due to unfair competition with cheap imported goods. Liberalisation in developing countries in general and southern Africa in particular, has entailed weakening the role of the state in national economic management. Governments are increasingly succumbing to the dictates of multinationals and are failing to enforce regulatory measures needed to protect the welfare of workers and their working conditions.

Na maior parte deste trabalho, estudamos a existência de involuções livres sobre algumas 4-variedades fechadas, com o mesmo tipo de homotopia do espaço total de algum fibrado de superfície sobre superfície, bem como uma generalização do teorema de Borsuk-Ulam para tais 4-variedades. Também estudamos a relação do teorema de Borsuk-Ulam, para aplicações da n-esfera em variedades, com a teoria de conível. / In the most part of this work, we study the existence of free involutions over some closed 4-manifolds with the same homotopy type of the total space of some surface bundle over surface, as well as a generalization of the Borsuk-Ulam theorem for such 4-manifolds. Also we study the relation of the Borsuk-Ulam theorem, for maps from the n-sphere into manifolds, with the colevel theory.

Gastrulation is a highly complex series of cellular rearrangements that leads to the internalization of the mesoderm and endoderm. The cellular behaviors that underlie morphogenesis are dependent upon changes in cell motility and polarity. Eph receptors belong to a family of receptor tyrosine kinases that are involved in a variety of developmental processes. This study is the first to examine the role EphA4 during Xenopus gastrulation. Morpholino oligonucleotide (MO) mediated knockdown of EphA4 resulted in attenuated mesoderm involution and reduced the expression of the posterior mesoderm marker brachyury (Xbra). Expression of EphA4 in the blastocoel roof was sufficient to promote ectopic Xbra expression. I show that EphA4 can regulate Xbra expression and involution movements by signaling through PAK1. Temporal regulation of Xbra was sufficent to rescue EphA4 induced gastrulation defects. This study has uncovered a novel EphA4/PAK1 pathway which is required for mesoderm involution and Xbra expression during Xenopus gastrulation.

Gastrulation is a highly complex series of cellular rearrangements that leads to the internalization of the mesoderm and endoderm. The cellular behaviors that underlie morphogenesis are dependent upon changes in cell motility and polarity. Eph receptors belong to a family of receptor tyrosine kinases that are involved in a variety of developmental processes. This study is the first to examine the role EphA4 during Xenopus gastrulation. Morpholino oligonucleotide (MO) mediated knockdown of EphA4 resulted in attenuated mesoderm involution and reduced the expression of the posterior mesoderm marker brachyury (Xbra). Expression of EphA4 in the blastocoel roof was sufficient to promote ectopic Xbra expression. I show that EphA4 can regulate Xbra expression and involution movements by signaling through PAK1. Temporal regulation of Xbra was sufficent to rescue EphA4 induced gastrulation defects. This study has uncovered a novel EphA4/PAK1 pathway which is required for mesoderm involution and Xbra expression during Xenopus gastrulation.

abstract INERT SUBGROUPS AND CENTRALIZERS OF INVOLUTIONS IN LOCALLY FINITE SIMPLE GROUPS &uml / Ozyurt, Erdal Ph. D., Department of Mathematics Supervisor: Prof. Dr. Mahmut Kuzucuo&amp / #728 / glu September 2003, 68 pages A subgroup H of a group G is called inert if [H : H Hg] is finite for all g 2 G. A group is called totally inert if every subgroup is inert. Among the basic properties of inert subgroups, we prove the following. Let M be a maximal subgroup of a locally finite group G. If M is inert and abelian, then G is soluble with derived length at most 3. In particular, the given properties impose a strong restriction on the derived length of G. We also prove that, if the centralizer of every involution is inert in an infinite locally finite simple group G, then every finite set of elements of G can not be contained in a finite simple group. In a special case, this generalizes a Theorem of Belyaev&amp / #8211 / Kuzucuo&amp / #728 / glu&amp / #8211 / Se&cedil / ckin, which proves that there exists no infinite locally finite totally inert simple group.

Central to the age-associated decrease in immune system function, characterised by the increase in the frequency and severity of infections and autoimmune diseases, is the decrease in production of naïve T cells by the thymus. This results from the targeted degeneration or involution of the thymus with age. One of the principal causes of involution is the loss of organisation and functionality of the thymic epithelium, which confers the primary function of the organ via interactive regulation of T cell development. Although the mechanisms that govern the deterioration of the thymic epithelium are poorly understood, a number of recent reports indicate that the transcription factor, Foxn1, is required to maintain this compartment in the postnatal thymus. Thus, the first aim of this study was to precisely profile Foxn1 expression levels in aging postnatal thymic epithelial cells. The second aim was to investigate the effects of upregulating Foxn1 in the aging thymus, which was achieved using a novel, regulatable Foxn1 mouse model generated during this study. In this study I show that Foxn1 is expressed at different levels in different postnatal thymic epithelial cell (TEC) sub-populations suggesting a dosage-dependent mode of action for Foxn1. Additionally, using two experimental approaches, I show that Foxn1 expression decreases with age in TECs, supporting the current data that implicate the loss of Foxn1 as a potential cause of thymus involution. Next, I generated a tissue-specific, regulatable Foxn1 mouse model that allowed me to modulate Foxn1 expression in the postnatal thymus. Firstly, using this model, I show that thymus involution can be prevented by the up-regulation and maintenance of Foxn1 expression from the onset of involution. Thymi that up-regulated Foxn1 were overtly larger and exhibited greater cellularity in both the thymocyte and epithelial compartments compared to age matched controls. Additionally, the larger TEC compartment contained a higher proportion of functional and proliferating TECs that upregulated a panel of genes involved in TEC development and function. Next, I show that Foxn1 up-regulation in aged, involuted thymi is sufficient to partially reverse involution, as shown by an increase in TEC organisation and intrathymic T cell numbers. While other strategies that promote thymic rebound or reversal have been reported, including cytokine treatment or sex steroid ablation, these approaches are complicated by side effects and toxicity. Hence, I propose a novel model for immune reconstitution through the regulation of Foxn1 expression in the postnatal thymus.

Freiburg i. Br., Univ., Diss., 2006.

Made available in DSpace on 2014-06-11T19:24:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2003Bitstream added on 2014-06-13T19:10:31Z : No. of bitstreams: 1 furini_la_me_prud.pdf: 1854498 bytes, checksum: bc75b7263deb271e75f40099f8267f28 (MD5) / Acada instante são reproduzidos, no mundo, processos sociais excludentes, os quais conferem padrões de inserção precária a diversos segmentos da população mundial. No Brasil estes processos são acirrados devido a grande concentração de riquezas nas mãos de poucos, pautados em ideologias que buscam justificar tal concentração, permitindo a convocação de pessoas para o sacrifício coletivo em nome da pátria e o afastamento das mesmas para que não partilhem de seus benefícios. A incorporação ou não destas ideologias decorre da formação das representações sociais pelos grupos atingidos, desse modo, a teoria das representações sociais norteou o desenvolvimento dessa pesquisa. Em meio a este contexto, a vulnerabilidade sócioespacial é agravada e consequentemente surgem casos extremos como o da população de rua - pessoas que usam a rua como local de moradia. Nesta pesquisa, analisamos especificamente o caso da população de rua de Presidente Prudente (SP). A despeito das adversidades e das políticas geridas por grupos de interesse, ocorre certo enfrentamento dessa vulnerabilidade no caso brasileiro. Este enfrentamento dilui-se nas limitações políticas ou na própria lógica da ação assistencial, que, em geral, limita-se a remediar ao invés de elaborar caminhos condizentes com uma resposta adequada ao caso. Inserido precariamente na sociedade, aquele que se encontra como morador de rua cria diversas estratégias de sobrevivência, o que confere uma particularidade ao lugar que ocupa socialmente. Considerando as escalas, o redimencionamento que estas implicam ao meio geográfico e aos fluxos que perpassam esse meio, analisamos o lugar e o vivido da população de rua como polo contrário do desenvolvimento tecnológico, da concentração das riquezas e das revoluções logísticas... . En dépit des adversités et des politiques gérées pour des groupes d'intérêts, se déroule certain confrontation de cette vulnérabilité dans le cas brésilien. Cette confrontation s'est diluée aux limites politiques ou à la propre logique de l'action assistencial, que en général, se limite à remedier au lieu d'élaborer segments assortis avec une réponse adéquate au cas. Incluse précairement dans la societé, celui que se rencontre comme frange-des gens, forme divers stratégies de survivance, ce que confère une privée au lieu que s'occupe socialement. En considérant les échelles, l'améliorement que les mêmes impliquent au milieu géographiques et aux flux que passent dans ce milieu, nous analysons le lieu et la vie de la frange-des gens comme pôle contraire...

Na maior parte deste trabalho, estudamos a existência de involuções livres sobre algumas 4-variedades fechadas, com o mesmo tipo de homotopia do espaço total de algum fibrado de superfície sobre superfície, bem como uma generalização do teorema de Borsuk-Ulam para tais 4-variedades. Também estudamos a relação do teorema de Borsuk-Ulam, para aplicações da n-esfera em variedades, com a teoria de conível. / In the most part of this work, we study the existence of free involutions over some closed 4-manifolds with the same homotopy type of the total space of some surface bundle over surface, as well as a generalization of the Borsuk-Ulam theorem for such 4-manifolds. Also we study the relation of the Borsuk-Ulam theorem, for maps from the n-sphere into manifolds, with the colevel theory.