No description available.

Les trihalométhanes (THM) et les acides haloacétiques (AHA) constituent les seules familles réglementées de sous-produits de la désinfection (SPD). Les SPD sont des composés issus de la réaction de la matière organique naturelle présente dans l’eau et du désinfectant lors du traitement de l’eau potable. La plupart de ces composés ne sont pas réglementés, même si plusieurs études ont montré que certains SPD peuvent présenter un risque toxicologique plus important que les THM et les AHA. De nos jours, très peu d’informations sont disponibles sur l’occurrence des SPD non-réglementés dans l’eau potable, en particulier dans les petits réseaux municipaux. Paradoxalement, les petits réseaux approvisionnés en eau de surface ont souvent des difficultés à mettre en place des traitements adéquats pour enlever les précurseurs de SPD dans l’eau soumise à la désinfection. L’eau potable des petits réseaux est ainsi plus vulnérable aux SPD et leur suivi y est d’autant plus important. Cette thèse s’est donc consacrée à améliorer les connaissances sur l’occurrence des SPD (et en particulier, les SPD non-réglementés) dans les petits réseaux de distribution d’eau potable, en étudiant notamment leur évolution spatiale et temporelle. Pour ce faire, deux campagnes d’échantillonnage ont été réalisées sur deux ans (entre 2010 et 2012) dans 25 petits réseaux du Québec et de Terre-Neuve-et-Labrador. Les THM, les AHA et trois autres familles de SPD non-réglementés, à savoir les haloacétonitriles, les halonitrométhanes et les haloacétones, ont été étudiés. Les résultats obtenus ont permis de mieux comprendre leur patron de variabilité spatio-temporelle, de modéliser leur présence et de développer un outil d’aide à la décision pour la mise en place d’une stratégie de suivi des SPD réglementés et non-réglementés. / Trihalomethanes (THMs) and haloacetic acids (HAAs) constitute the only regulated disinfection by-products (DBPs) in various countries. DBPs are compounds formed during drinking water treatment, from the reaction between natural organic matter and the disinfectant. Most DBPs are not regulated, even if they may have more pronounced toxicological effects than regulated ones. There is currently very little information about the occurrence of non-regulated DBPs, particularly in small water systems (SWS). Paradoxically, in many cases, SWS supplied by surface waters lack adequate treatment processes to remove DBP precursors in water subjected to the disinfection process. Their tap water may be more vulnerable to the presence of DBPs. This thesis is dedicated to improving the knowledge of the occurrence of DBPs (especially non-regulated DBPs) in SWS by studying their spatial and temporal variability. To do that, two sampling programs were carried out in 25 SWS during two years (between 2010 and 2012) in Canada. Small systems in the provinces of Newfoundland & Labrador and Quebec were considered. The following DBPs were measured during the study: THMs, HAAs, haloacetonitriles, haloketones and halonitromethanes. The obtained results contribute to a better understanding of the DBP spatio-temporal variation patterns, to establishing models to evaluate their levels and to developing decision-making schemes for simultaneously monitoring various families of DBPs, including non-regulated DBPs.

Following the end of the colonial period, Latin America became a thriving market for goods from the industrializing world, particularly the United States, Great Britain, and France. This thesis explores the sociocultural implications of importation into Mexico City and Caracas, Venezuela, situating the flow of commodities within cultural processes. It analyzes how ordinary people in the two cities interacted with goods from abroad. While most studies of this phenomenon focus on elites, this research suggests that they did not comprise the only group to desire, acquire, and display imported commodities. In Mexico City, non-elites could achieve upward mobility by displaying European items. In Caracas, powerful external commercial ties allowed city residents of most classes to obtain foreign commodities and construct their identity by way of them. Thus, people throughout the social strata associated with imported goods, leading to internal and external effects on cultural identity. / Tinker Foundation / University of North Carolina at Chapel Hill

En Amérique du Nord, les populations de roseau commun (Phragmites australis) ont connu une grande expansion depuis une centaine d'années, à la suite de l'introduction d'un génotype eurasiatique très compétitif. Cette invasion biologique constitue un problème environnemental important, car les marais envahis par le roseau deviennent peu propices à la survie d'une flore et d'une faune diversifiées. Malgré le fait que le roseau ait été beaucoup étudié en Amérique du Nord, on ne sait pas vraiment de quelle manière cette plante envahissante se propage sur de vastes territoires. L'objectif principal de cette thèse est donc de mieux comprendre les processus d'envahissement à différentes échelles de cette espèce à fort pouvoir de dissémination. On émet notamment l'hypothèse que le développement d'un réseau routier engendre tout un lot de ressources favorables à l'implantation et la propagation du roseau. Dans un premier temps, une analyse génétique historique a montré que le génotype eurasiatique de roseau est présent au Québec depuis au moins 1916, mais qu'il était rare avant les années 1970. C'est le développement du réseau autoroutier au cours des années 1960 et 1970 qui a probablement contribué à l'expansion du génotype dans le paysage québécois. Dans un deuxième temps, l'analyse statistique de données de terrain régionales assistée par un système d'information géographique a permis de montrer que l'importance d'une route (largeur, trouée lumineuse, entretien, trafic routier) est associée de manière positive à la probabilité d'y trouver du roseau sur ses berges ou dans ses fossés de drainage, surtout si la route repose sur des dépôts de surface mal drainés. Dans un troisième temps, un système d'information géographique et des ensembles de photographies aériennes historiques ont permis de cartographier les populations de roseau présentes dans des marais adjacents au réseau autoroutier du Québec. Malgré le fait que le processus d'invasion du roseau débute, dans tous les cas analysés, après la construction de l'autoroute, on a pu constater que la plante ne se propage pas toujours des fossés de drainage de l'autoroute vers le marais adjacent. Parfois, c'est le phénomène inverse qui se produit. En somme, cette thèse présente un portrait spatio-temporel de la situation du roseau eurasiatique au Québec. Elle a permis, par une approche multi-échelle, d'établir une relation entre la dissémination d'une plante envahissante et l'expansion du réseau routier. Elle a aussi permis de proposer certaines recommandations au niveau de l'aménagement du territoire afin de prévenir l'envahissement ou de contrôler la propagation de la plante.

Enjeu majeur de la planification métropolitaine, la gestion de l’étalement urbain soulève le défi de saisir un phénomène complexe dans son ensemble. Cette complexité renvoie à la difficulté de proposer une représentation d’un problème toujours spécifique à un territoire, et perçu différemment par un ensemble varié d’acteurs. Les approches méthodologiques d’aide au diagnostic comme la méthode de cartographie cognitive de groupe semble adéquate pour faire émerger une représentation partagée des mécanismes explicatifs d’un phénomène, mais son utilisation invite à s’interroger sur la crédibilité scientifique des résultats obtenus. Une expérience de cartographie de groupe a d’abord été testée in situ puis évaluée de façon réflexive entre 2006 et 2007. Les recommandations proposées pour manipuler la complexité territoriale et accompagner le débat ont joué un rôle décisif sur un processus de concertation des acteurs de l’étalement urbain dans la région de Québec. Celui-ci a débuté par une analyse de la presse écrite publiée entre 2006 et 2009 afin d’explorer les représentations des acteurs ainsi que leur interaction potentielle. Un forum de discussion a ensuite été organisé sur une journée en 2009. Une trentaine d’acteurs ont ainsi négocié une représentation partagée des enjeux de l’étalement, de ses principaux mécanismes et des interventions qui devraient être priorisées. Les résultats de ce forum, soit un ensemble de cartes cognitives et leur négociation, sont enfin analysés en appliquant notamment la théorie des graphes. On observe ainsi que l’étalement urbain émerge de mécanismes territoriaux complexes et tortueux. Les représentations produites révèlent des contradictions entre les effets recherchés et subis de l’étalement, mais aussi les enjeux individuels et collectifs difficiles à concilier. Toutefois, les acteurs de Québec ont des représentations plus complémentaires que contradictoires et un modèle consensuel est mis en évidence. Ce modèle, rigoureusement comparé à la littérature scientifique récente et la plus citée sur l’étalement urbain en Amérique du nord, renforce à la fois sa crédibilité et sa spécificité. L’importance d’évaluer les représentations partagées construites lors de processus de concertation est ainsi démontrée, ce qui conduit finalement à proposer une approche générale pour manipuler la complexité territoriale, utile aux outils d’aide au diagnostic. / Managing urban sprawl at a metropolitan scale challenges planners to comprehend a complex phenomenon holistically. The complexity comes from the difficulty of building a shared understanding of a problem that is always specific to a particular territory, but which is subject to a range of perceptions among a varied set of stakeholders. Current decision-support tools such as group cognitive mapping are increasingly used to diagnose complex and fuzzy problems, and promise to help develop a shared appreciation of concepts and explanatory mechanisms. However the results obtained often remain questionable in terms of scientific credibility. A preliminary trial of group cognitive mapping was implemented in situ and assessed reflexively between 2006 and 2007. Recommendations for improving the handling of territorial complexity, and for supporting the debate among stakeholders, led to further investigation into how best to consult those with an interest in urban sprawl. An analysis of written press coverage, published between 2006 and 2009, was used to explore stakeholders’ representations, and the potential for networking and interaction between stakeholders. Then, a one-day forum, held in 2009, was organized around twelve discussion groups. This allowed about thirty stakeholders with very diverse roles in the Quebec City metropolitan area to negotiate a shared understanding of sprawl, including the main issues, the explanatory mechanisms, and the priority interventions that should be considered. The result of the forum, expressed as a series of group cognitive maps, and summaries of the negotiation processes that led to them, was then analysed using methods based to a large extent on graph theory. From this we can observe that urban sprawl seems to emerge from complex and tortuous mechanisms, underlying contradictions between desired effects and their counterparts, as well as between individual and collective interests that are hard to reconcile. However, once surfaced, the stakeholders’ representations were more complementary than contradictory, and as a result it was possible to reach a consensus on a shared conceptual model. In the final stage of this research, the group model was rigorously compared to recent and most-cited scientific literature in North America, confirming both its scientific credibility and its applicability. The results thus reveal the relevance of assessing group models built interactively during the consultation process, and this leads to a proposed general approach for handling territorial complexity as a cornerstone of decision-support tools for the diagnosis of urban problems.

Tableau d'honneur de la Faculté des études supérieures et postdoctorales, 2017-2018 / Cette thèse s’intéresse au développement d’un système intelligent d’aide à la décision (SIAD) destiné à la conception, à la gestion et à l’optimisation des programmes de suivi de la qualité de l’eau (PSQE). Toute son originalité repose sur le fait qu’elle aborde la question dans une perspective holistique qui se traduit par le développement d’une approche participative dans le but de déterminer les besoins en connaissances sur la qualité et la quantité de l’eau sur lesquels se base le SIAD pour assister les gestionnaires de PSQE à toutes les étapes de la planification, de la gestion et de l’optimisation d’un PSQE. ... / This thesis focuses on the development of an intelligent decision-support system (IDSS) to plan, manage and optimize water quality monitoring programs (WQMPs). The main originality of this thesis is to have approached thequestion of planning, managing and optimizing WQMPs in a holistic manner. The holistic approach transcends into the developing of a participative approach to identify knowledge needs on water quality and quantity to feed an IDSS which assists WQMP managers in every aspect of planning, managing and optimizing WQMPs. ...

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-06-01T12:09:03Z No. of bitstreams: 1 ingridestevampereira.pdf: 2004254 bytes, checksum: 326e3188dc98d9fc4ddc417af89ebc1e (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-06-02T15:12:44Z (GMT) No. of bitstreams: 1 ingridestevampereira.pdf: 2004254 bytes, checksum: 326e3188dc98d9fc4ddc417af89ebc1e (MD5) / Made available in DSpace on 2017-06-02T15:12:44Z (GMT). No. of bitstreams: 1 ingridestevampereira.pdf: 2004254 bytes, checksum: 326e3188dc98d9fc4ddc417af89ebc1e (MD5) Previous issue date: 2017-02-22 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / CNPq - Conselho Nacional de Desenvolvimento Científico e Tecnológico / A talidomida é uma potente droga anti-inflamatória empregada no tratamento de diversas patologias, incluindo Eritema Nodoso Leproso (ENL), câncer, doença de Crohn e outras desordens inflamatórias e vasculares. Entretanto, seus efeitos tóxicos e teratogênicos tornam sua utilização limitada e motivam pesquisas para a síntese de análogos que apresentem eficácia semelhante na imunomodulação, sem efeitos tóxicos. Diversos análogos da talidomida vêm sendo desenvolvidos no laboratório de química da UFJF. Em estudos anteriores, mostramos que a introdução de dois anidridos ftálicos na composição aumenta significativamente a atividade biológica e solubilidade em água do composto, sem aumento da toxicidade em modelos experimentais in vitro e in vivo. O presente trabalho visa a síntese de dois novos compostos análogos da talidomida, CAT-15 e CAT-16, formados por apenas um derivado anidrido ftálico aberto, mantendo um grupo amino livre, e a avaliação da sua atividade anti-inflamatória utilizando linhagem de célula HT-29 e células mononucleares de sangue periférico humano (PBMC) estimuladas com LPS. A citotoxicidade dos compostos foi avaliada pelo ensaio do MTT, com tratamento por 18 horas para células HT-29 e por 24 e 48 horas para PBMC, usando concentrações crescentes de talidomida, CAT-15, CAT-16. A dexametasona foi utilizada como controle positivo. A produção de TNF-α, CXCL-10, IL-6, IL-8 e IL-10 foi avaliada pelo método de ELISA. Os novos compostos não foram tóxicos para as células HT-29 e PBMC em nenhuma das concentrações testadas, com exceção de CAT-16 a 1600µM. Células HT-29 produziram grande quantidade de CXCL-10 em resposta ao LPS e os resultados deste trabalho mostram que a talidomida e os análogos CAT-16 e CAT-15 apresentam atividade inibitória sobre a produção desta quimiocina. O composto CAT-16 modulou a produção de CXCL-10 em concentrações menores que a talidomida em ambos os modelos de tratamento (simultâneo e prétratamento). Em contrapartida, a modulação por CAT-15 foi observada apenas no modelo de pré-tratamento. Com relação a IL-8, a talidomida e o CAT-16 inibiram a produção desta citocina por células HT-29 apenas na concentração de 100µM. Ao contrário das células HT-29, o PBMC produziu TNF-α em resposta ao LPS, tendo a talidomida e o análogo CAT-16 apresentado capacidade de inibição da produção do TNF-α em ambos os tempos de tratamento. O análogo CAT-15 não influenciou a produção de TNF-α por PBMC em nenhuma das concentrações e tempos de tratamento. Este estudo também mostra a atividade da talidomida e dos nos análogos sobre a produção de IL-6 e IL-10 por PBMC, havendo significativa inibição da produção de IL-6 por todos os compostos e tempos de tratamento e sobre IL-10 pelo composto CAT-15 após 48 horas de incubação. Nossos resultados sugerem a aplicabilidade dos novos compostos, CAT-15 e CAT-16, no controle de respostas inflamatórias uma vez que inibiram a produção de moléculas chave como TNF-α, IL6, IL-10, IL-8 e CXCL-10. Ainda, esses compostos possuem estruturas simplificadas, têm baixo custo de produção, são hidrossolúveis e não possuem centro quiral. Esses resultados podem contribuir no desenvolvimento de novas estratégias de tratamento para certas condições inflamatórias. / Thalidomide is a potent anti-inflammatory drug used in the treatment of various pathologies including Erythema Nodosum Leprosum (ENL), cancer, Crohn's disease and other inflammatory and vascular disorders. However, its toxic and teratogenic effects make its use limited and motivate research groups to synthesize analogues presenting similar immunomodulation efficacy, without toxic effects. Several analogs of thalidomide have been developed in the laboratory of chemistry of the UFJF. Previously, we have shown that introduction of two phthalic anhydrides into the composition significantly enhances biological activity and water solubility, without enhanced toxicity. The present work aims at the synthesis of two new analogues of thalidomide, CAT-15 and CAT-16, formed by only one open phthalic anhydride derivative, maintaining a free amino group, and the evaluation of its anti-inflammatory activity using HT- 29 and human peripheral blood mononuclear cells (PBMCs) stimulated with LPS. The cytotoxicity of the compounds was evaluated by the MTT assay, with 18 hours treatment for HT-29 cells and for 24 and 48 hours for PBMC, using increasing concentrations of thalidomide, CAT-15, CAT-16. Dexamethasone was used as a positive control. Production of TNF-α, CXCL-10, IL-6, IL-8 and IL-10 was evaluated by the ELISA method. The novel compounds were not toxic to HT-29 and PBMC cells at any of the concentrations tested, with the exception of CAT-16 at 1600μM. HT-29 cells produced large amounts of CXCL-10 in response to LPS and the results of this work show that thalidomide and the CAT-15 and CAT-16 analogs exhibit inhibitory activity on the production of this chemokine. CAT-16 compound modulated the production of CXCL-10 at lower concentrations than thalidomide in both treatment models (simultaneous and pretreatment). In contrast, CAT-15 modulation was observed only in the pre-treatment model. Regarding IL-8, thalidomide and CAT-16 inhibited their production by HT-29 cells only at the concentration of 100 μM. Unlike HT-29 cells, PBMC produced TNF-α in response to LPS, with thalidomide and CAT-16 analog being able to inhibit TNF- production at both treatment times. The CAT-15 analogue did not influence the production of TNF-α by PBMC at any of the concentrations and treatment times. This study also shows the activity of thalidomide and the analogs on IL-6 and IL-10 production by PBMC, with significant inhibition of IL-6 production by all compounds and treatment times and on IL-10 by compound CAT-15 after 48 hours of incubation. Our results suggest the applicability of the new compounds, CAT-15 and CAT-16, in the control of inflammatory responses since they inhibited the production of key molecules such as TNF-α, IL-6, IL-10, IL-8 and CXCL-10. Furthermore, these compounds have simplified structures, and low cost of production, are water soluble and have no chiral center. These results may contribute to the development of novel treatment strategies for certain inflammatory conditions.

Prenatal stress may increase the risk for depression in offspring and it has been suggested that this could be linked to alterations in tryptophan metabolism, leading to serotonergic changes. Dietary patterns based on the Mediterranean (Med) diet, which includes foods rich in nutrients involved in the tryptophan-serotonin pathway, have been linked to depressive symptom improvements when used as an intervention. This thesis examined, in a mouse model, whether a Med-based diet normalized depressive-like behaviour and changes in the serotonin system in the colon and hippocampus resulting from a repeated physical restraint stressor administered during the second trimester in adult C57BL/6N female and male offspring. The Med-based diet modulated behaviour and hippocampal serotonin receptors primarily in females and changed the enzyme involved in the colonic serotonergic pathway in males. These results suggest that a Med-based diet may help improve behavioural disturbances stemming from prenatal stress in a sex-specific way, perhaps through its actions on the gut-brain serotonin system.

Le film hydrolipidique est « l’ultime frontière entre l’organisme et l’environnement ». Ainsi, il offre à la peau une bonne protection et contribue largement à ses propriétés. Cependant, il peut être impliqué dans plusieurs perturbations cutanées. Le but de ce travail était d’obtenir un profil global de l’ensemble des lipides cutanés de surface, riche en informations structurales et capable de décrire l’organisation de ces molécules, permettant de suivre l’évolution physiologique du film hydrolipidique au niveau moléculaire. Plusieurs approches analytiques ont été développées et des outils statistiques et chimiométriques ont été utilisés pour exploiter les résultats.La caractérisation des lipides cutanés de surface (LCS) a été réalisée en chromatographie en phase gazeuse à haute température couplée à la spectrométrie de masse (HT-GC/MS). Le protocole analytique a été développé en conservant les structures lipidiques dans leur état intact. Plus de 200 composés ont été identifiés et répartis en 5 classes : acides gras libres, hydrocarbures, cires, stérols et glycérides. L’acide palmitique (C16:0) et l’acide sapiénique (C16:16) sont prépondérants et entrent dans la structure de très nombreux composés. Plusieurs approches quantitatives ont été mises en place : calcul des descripteurs chromatographiques, normalisation interne pour l’analyse par classe et exploitation chimiométrique des composés considérés individuellement.Trois problématiques ont été explorées par ces techniques et ont conduit aux résultats suivants :La répartition des LCS sur différentes zones corporelles se traduit par un ratio squalène/cholestérol plus élevé dans les zones riches en glandes sébacées que dans les zones pauvres. Ce descripteur est ainsi un bon critère d’évaluation de la balance sécrétion sébacée/desquamation. L’évolution des LCS en fonction de la localisation géographique et/ou la couleur de la peau a été étudiée en cherchant les variations de la composition par HT-GC/MS et de l’organisation par spectroscopie Raman. Une différence de composition a été mise en évidence entre les volontaires en fonction de la localisation géographique : le composé le plus impliqué est l’acide sapiénique (C16:1Δ6). Une différence de conformation (trans/gauche) au niveau des chaînes alkyles a été détectée.Enfin, l’adaptation de la barrière cutanée après la naissance a été déjà signalée mais sa traduction au plan moléculaire a pu être étudiée par le protocole analytique développé, chez les nourrissons dès les premiers jours après la naissance jusqu’à l’âge de 6 mois. Une diminution de la quantité globale de sécrétion sébacée a été observée, avec en parallèle, une augmentation sélective du cholestérol estérifié par des acides gras d’origine épidermique. Ceci indique un accroissement de la participation relative des lipides épidermiques dans le film hydrolipidique comme résultat d’une diminution de la sécrétion sébacée.Les approches analytiques développées dans ce travail de thèse permettent une caractérisation moléculaire fine des LCS en vue d’étudier l’évolution physiologique du film hydrolipidique. Les outils statistiques et chimiométriques ont permis une exploitation plus poussée des résultats pour extraire des informations inaccessibles par les approches classiques. Ce travail d’investigation offre de nombreuses perspectives, très prometteuses dans le domaine médical et dans le domaine cosmétique. / Skin hydrolipidic film is "the final frontier between the organism and the environment." Thus, it provides skin protection and contributes to its properties. However, it may be involved in several skin disturbances. The aim of this study was to obtain an overall profile of skin surface lipids (SSLs), rich in structural information and able to describe the organization of these molecules. This information allows monitoring the physiological evolution of hydrolipidic film at the molecular level. Several analytical approaches have been developed and chemometric and statistical tools were used to improve the interpretation of the results.SSL characterization was performed using high-temperature gas chromatography coupled with mass spectrometry (HT-GC/MS). The analytical protocol has been developed keeping the lipids in their intact structures. Over than 200 compounds were identified in the same run. These compounds have been classified in five lipid classes: free fatty acids, hydrocarbons, waxes, sterols and glycerides. The palmitic acid (C16:0) and sapienic acid (C16:16) are predominant and participate in the structure of many compounds. Several quantitative approaches have been implemented: calculation of chromatographic descriptors, normalization of the peak area for analysis by class and chemometric exploitation of individual compounds data.Three issues were explored by these techniques and lead to have the following results:The SSL distribution on different areas of the body, expressed as a squalene / cholesterol ratio, is higher in body areas rich in sebaceous glands than in poor areas. This descriptor is thus a good criterion for sebum secretion / desquamation balance measurement.The SSL evolution based on the geographical location and / or color of skin has been investigated by studying the variations in the composition and organization using HT-GC/MS and Raman spectroscopy. A difference in composition has been demonstrated between the volunteers according to geographical location: the most involved compound is the sapienic acid (C16: 1Δ6). A difference in conformation (trans / gauche) of at the alkyl chains was detected. Skin barrier adaptation after birth has already been reported. In this study, its evolution at the molecular level has been studied in infants from the first days after birth until the age of 6 months. A decrease in the total amount of sebaceous secretion was observed with, in parallel, an increase of cholesterol esterified with fatty acids of epidermal origin. This indicates an increase in the relative participation of epidermal lipids in the hydrolipidic film as the result of a decrease in sebaceous secretion. The analytical approaches developed in this thesis provide a detailed molecular characterization of SSLs in order to study the physiological evolution of the skin hydrolipidic film. Statistical and chemometric tools have allowed further exploitation of the results to extract information not accessible by conventional approaches. This investigative work offers many opportunities, promising in medicine and in cosmetics.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2014-08-06T11:17:00Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Volumes_e_curvaturas_medias_na_geometria_de_finsler.pdf: 818570 bytes, checksum: fce77ff7f92ae9cc2bf9af2aa0318c4c (MD5) / Made available in DSpace on 2014-08-06T11:17:00Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Volumes_e_curvaturas_medias_na_geometria_de_finsler.pdf: 818570 bytes, checksum: fce77ff7f92ae9cc2bf9af2aa0318c4c (MD5) Previous issue date: 2012-04-16 / In Finsler geometry, we have several volume forms, hence various of mean curvature forms. The two best known volumes forms are the Busemann-Hausdorff and Holmes- Thompson volume form. The minimal surface with respect to these volume forms are called BH-minimal and HT-minimal surface, respectively. Let (R3; eFb) be a Minkowski space of Randers type with eFb = ea+eb; where ea is the Euclidean metric and eb = bdx3; 0 < b < 1: If a connected surface M in (R3; eFb) is minimal with respect to both volume forms Busemann-Hausdorff and Holmes-Thompson, then up to a parallel translation of R3; M is either a piece of plane or a piece of helicoid which is generated by lines screwing along the x3-axis. Furthermore it gives an explicit rotation hypersurfaces BH-minimal and HT-minimal generated by a plane curve around the axis in the direction of eb] in Minkowski (a;b)-space (Vn+1; eFb); where Vn+1 is an (n+1)-dimensional real vector space, eFb = eaf eb ea ; ea is the Euclidean metric, eb is a one form of constant length b = kebkea; eb] is the dual vector of eb with respect to ea: As an application, it give us an explicit expression of surface of rotation “ forward” BH-minimal generated by the rotation around the axis in the direction of eb] in Minkowski space of Randers type (V3; ea+eb): / Na Geometria de Finsler, temos várias formas volume, consequentemente várias formas curvaturas médias. As duas mais conhecidas são as formas de volumes Busemann- Hausdorff e Holmes-Thompson. As superfícies mínimas com respeito a estes são chamados superfícies BH-mínimas e HT-mínimas, respectivamente. Seja (R3; eFb) um espaço de Minkowski do tipo Randers com eFb = ea+eb; onde ea é a métrica Euclidiana e eb = bdx3;0 < b < 1: Uma superfície em (R3; eFb) conexa M é mínima com respeito a ambas formas volumes Busemann-Hausdorff e Holmes-Thompson, então a menos de uma translação paralela de R3; M é parte de um plano ou parte de um helicóide, a qual é gerada pela rotação de uma reta (perpendicular ao eixo x3) ao longo do eixo x3: Ademais podemos obter explicitamente hipersuperfícies de rotação BH-mínima e HT-mínima geradas por uma curva plana em torno do eixo na direção de eb] num espaço (a; b) de Minkowski (Vn+1; eFb); onde Vn+1 é um espaço vetorial de dimensão (n+1); eFb = eaf eb ea ; ea é a métrica Euclidiana, eb é uma 1-forma constante com norma b := kebkea; eb] é o vetor dual de eb com respeito a a: Como aplicação, se dá uma expressão explícita de superfície de rotação completa “forward” BH-mínima gerada pela rotação em torno do eixo na direção de eb] num espaço de Minkowski do tipo Randers (V3; ea+eb):