Identification of Material Parameters from Temperature Measurements in Radio Frequency Ablation

The mathematical simulation of the method of radio frequency ablation (RFA) offers an opportunity to improve the success of the RFA. The results of the RFA depend highly on the experience of the radiologist. A simulation will offer a prediction of the results which can be used to adapt the setting and enable a complete destruction of the tumor, e.g. by adapting the probe's position. A good simulation needs as much information of the reality as possible. Especially the material properties pose a challenge since they vary from patient to patient, they can not be measured in vivo and they additionally change during the ablation. The aim of this thesis is to develop a mathematical model for the identification of the material parameters from temperature measurements and apply it to appropriate data sets. At first a minimization problem is formulated, where the difference between the measured temperature and the calculated temperature is minimized with respect to the material parameters. The temperature distribution is calculated with a coupled system of partial differential equations. Different approaches are considered which depend on the diverse modeling of the material parameters. The parameters are modeled as constant values as well as temperature dependent, tissue dependent and also spatially distributed. The advantages and disadvantages of the diverse models are illustrated by the numerical results for the identification with artificial temperature distributions as well as real temperature measurements

Identification of Material Parameters from Temperature Measurements in Radio Frequency Ablation

The mathematical simulation of the method of radio frequency ablation (RFA) offers an opportunity to improve the success of the RFA. The results of the RFA depend highly on the experience of the radiologist. A simulation will offer a prediction of the results which can be used to adapt the setting and enable a complete destruction of the tumor, e.g. by adapting the probe's position. A good simulation needs as much information of the reality as possible. Especially the material properties pose a challenge since they vary from patient to patient, they can not be measured in vivo and they additionally change during the ablation. The aim of this thesis is to develop a mathematical model for the identification of the material parameters from temperature measurements and apply it to appropriate data sets. At first a minimization problem is formulated, where the difference between the measured temperature and the calculated temperature is minimized with respect to the material parameters. The temperature distribution is calculated with a coupled system of partial differential equations. Different approaches are considered which depend on the diverse modeling of the material parameters. The parameters are modeled as constant values as well as temperature dependent, tissue dependent and also spatially distributed. The advantages and disadvantages of the diverse models are illustrated by the numerical results for the identification with artificial temperature distributions as well as real temperature measurements

Islam in Portuguese-Speaking Areas

Muslims are citizens and active members of society in nearly all lusophone areas. Among the Portuguese-speaking African countries, Guinea Bissau and Mozambique have long-standing Muslim populations, while, Angola, for example, received immigrants from Islamic majority countries only recently. The Islamic presence in Portugal goes back to Gharb al-Andalus, but the contemporary Muslim communities must be understood as a postcolonial phenomenon. Brazil, East Timor and Macao, also have particular historical experiences and differing present day Muslim populations.All cases differ significantly, but Muslims in lusophone spaces do share some similar socio-cultural point of comparison. In each case, Muslims are treated as representatives of a religious minority (except Guinea-Bissau); and in many cases Muslims represent ethnic backgrounds that differ from the dominant society. Furthermore, international migration reconfigures several lusophone fields, often leading to the increasing diversification. New transnational links have emerged among Muslims, often based on shared experiences in current national or local socio-historical contexts, on ethnicity or common language – which in many cases, is Portuguese.Les Musulmans sont des citoyens et des membres actifs de la société dans presque tous les espaces lusophones. Parmi les pays africains de langue portugaise, la Guinée-Bissau et le Mozambique ont des populations musulmanes établies de longue date, alors que l’Angola, par exemple, n’a accueilli que récemment des immigrés de pays à majorité islamique. La présence islamique au Portugal remonte à Gharb al-Andalus, mais les communautés musulmanes contemporaines doivent être comprises comme un phénomène post-colonial. À l’heure actuelle, le Brésil, Timor oriental et Macao, possèdent également des expériences historiques particulières et des populations musulmanes différentes.Tous les cas diffèrent sensiblement mais les Musulmans présents dans les espaces lusophones sont comparables à bien des égards sur le plan socioculturel. Toujours, sauf en Guinée-Bissau, les Musulmans sont perçus comme les représentants d’une minorité religieuse, et très souvent, ils ont des origines ethniques qui diffèrent de celles de la société dominante. De plus, les migrations internationales qui reconfigurent certains domaines lusophones, conduisent souvent à une augmentation de la diversité. De nouveaux liens transnationaux ont émergé parmi les Musulmans, dans les contextes nationaux et socio-historiques actuels, fondés sur l’ethnie ou la langue commune – laquelle, dans bien des cas, est le Portugais.Os muçulmanos são cidadãos e membros activos da sociedade em quase todas as áreas lusófonas. Entre os PALOPs, Guiné-Bissau e Moçambique têm populações muçulmanas de longa data, enquanto Angola, por exemplo, recebe só recentemente imigrantes de países maioritariamente islâmicos. A presença islâmica em Portugal remonta a Gharb al-Ândalus, no entanto as comunidades muçulmanas contemporâneas devem ser compreendidas como um fenómeno pós-colonial. Brasil, Timor-Leste e Macau também têm experiências históricas particulares e contam com uma comunidade muçulmana cujas características diferem significativamente.Todos os casos diferem, mas os muçulmanos nos espaços lusófonos compartilham algumas similaridades na comparação de pontos sócio-culturais. Em cada caso, os muçulmanos são vistos como representantes de uma minoria religiosa (excepto Guiné-Bissau); e em muitos casos os muçulmanos representam origens étnicas que diferem da sociedade dominante. Ademais, a migração internacional que reconfigura diversos campos lusófonos, conduz frequentemente à crescente diversificação. Novas ligações transnacionais emergiram entre muçulmanos, na base de experiências comuns em actuais contextos sócio-historicos nacionais ou locais, da etnicidade ou no idioma dominante – que maioritariamente, é o português

Diasbola: futebol e emigração portuguesa

O artigo serve de introdução ao dossiê “Futebol e emigração portuguesa”, proporcionando uma visão comparativa das conclusões do projeto de investigação internacional Diasbola, dedicado ao papel do futebol entre emigrantes portugueses e luso-descendentes de oito contextos diaspóricos. O objetivo foi caracterizar o futebol em comparação com outros elementos culturais utilizados pelos migrantes como meios de ligação ao seu país de origem, em processos de construção de comunidade e performance de “portugalidade”. Partimos da hipótese de que o futebol, que constitui um importante fenómeno sociocultural na sociedade portuguesa, representa um elemento particularmente poderoso na vida cultural quotidiana dos emigrantes, bem como um ponto de referência crucial na ligação destes ao seu local de origem. Sustentados por material etnográfico, os resultados da investigação confirmam claramente esta hipótese, mas contradizem a sua conotação algo restrita ou unilateral: embora a formação social e as diversas funções do futebol sejam moldadas por cada contexto diaspórico particular, este fenómeno proporciona também uma dinâmica que dá forma a tais contextos e condições

Stochastic collocation for optimal control problems with stochastic pde constraints

pre-printWe discuss the use of stochastic collocation for the solution of optimal control problems which are constrained by stochastic partial differential equations (SPDE). Thereby the constraining SPDE depends on data which is not deterministic but random. Assuming a deterministic control, randomness within the states of the input data will propagate to the states of the system. For the solution of SPDEs there has recently been an increasing effort in the development of efficient numerical schemes based upon the mathematical concept of generalized polynomial chaos. Modal-based stochastic Galerkin and nodal-based stochastic collocation versions of this methodology exist, both of which rely on a certain level of smoothness of the solution in the random space to yield accelerated convergence rates. In this paper we apply the stochastic collocation method to develop a gradient descent as well as a sequential quadratic program (SQP) for the minimization of objective functions constrained by an SPDE. The stochastic function involves several higher-order moments of the random states of the system as well as classical regularization of the control. In particular we discuss several objective functions of tracking type. Numerical examples are presented to demonstrate the performance of our new stochastic collocation minimization approach

Representing Islam and Lisbon Youth

While recent immigration from Muslim countries contributes to the diversification of Muslim life in Portugal, postcolonial people of Indian-Mozambican background continue playing a key role Islamic associational work. One example is the Youth Association of the Islamic Community (CilJovem) in Lisbon. Since September 11, its members are frequently asked to speak about Islam-related issues in the Portuguese media. Islam and Muslim-ness are important to them and they have become more engaged in Muslim activities at the international level. A study which compares cultural attitudes of these young Portuguese Sunni Muslims with those of non-Muslim peers reveals little difference: they are deeply attached to their city and home country and must also be seen as typical representatives of the middle class Lisbon youth.Alors que l’immigration récente en provenance des pays musulmans contribue à la diversification de la vie musulmane au Portugal, la communauté post-coloniale issue de l’émigration indo-mozambicaine joue un rôle essentiel dans le travail associatif. L'Association des Jeunes de la Communauté Islamique de Lisbonne (CilJovem) en est un exemple. Depuis le 11 septembre, ses membres sont souvent sollicités par les médias portugais pour parler des sujets relatifs à l’islam. Pour eux, l’islam et la musulmanité sont importants et ils s’engagent de plus en plus dans des activités musulmanes à un niveau international. Une étude comparative des attitudes culturelles de ces jeunes mulsumans sunnites portugais et des non-musulmans révèle peu de différences : ils sont profondément attachés à leur ville et à leur pays et doivent également être vus comme représentatifs de la jeunesse de la classe moyenne de Lisbonne.Apesar da imigração recente oriunda de países muçulmanos contribuir para a diversificação da vida muçulmana em Portugal, a população pós-colonial de origem indo-moçambicana continua a desempenhar um papel pivotal no trabalho associativo islâmico. Um dos exemplos é a Commissão de Jovens da Comunidade Islâmica (CilJovem) em Lisboa. Desde o Setembro 11 que os seus membros são frequentemente abordados para falar de assuntos relacionados com o Islão para os media portugueses. O Islão e o ser muçulmano são importantes para eles e tornaram-se mais envolvidos em actividades muçulmanas a nível internacional. Um estudo comparativo das atitudes culturais destes jovens portugueses sunitas com aqueles dos seus pares não-muçulmanos revela poucas diferenças : eles sentem-se profundamente ligados à sua cidade e país de origem, e devem ser também encarados como representantes típicos da juventude da classe média lisboeta

Main trends and patterns in Women’s Football Migration

Paper presented at the International conference “Globalization, Migration and Development: The role of Football from a transnational perspective,” at Maastricht University, co-organized by Sport Science Institute of the University of Lausanne, 23 June 201

Grundlegende Untersuchungen zum Fließpressen metallischer Kleinstteile

Diese Arbeit befasst sich mit dem Fließpressen metallischer Kleinstteile, wobei insbesondere auf die bei der Miniaturisierung auftretenden Größeneffekte eingegangen wird. Einen wesentlichen Schwerpunkt bilden grundlegende Untersuchungen zu Miniaturisierungseffekten bei der Reibung und deren Auswirkungen auf die erforderlichen Prozesskräfte und die Formausbildung. Des weiteren wird der Einfluss der Mikrostruktur auf den Prozess untersucht.This work deals with the extrusion of small metallic parts, whereby the size effects that occur during miniaturization are discussed in particular. An essential focus are fundamental studies on miniaturization effects in friction and their effects on the required process forces and the shape formation. The influence of the microstructure on the process is also examined

Mapping the Return Migration Research Field

This working paper presents an overview of recent literature on the theme of return migration, with particularly emphasis on works of relevance to our understanding of this topic in a contemporary Portuguese migration context. The discussion integrates insights and perspectives from empirically-informed studies with more long-standing theoretical ideas relating to return migration utilizing the idea of ‘generation’. Added to this is emphasis upon the role of social ties in understanding return migration, in particular family relationships, as well as an appreciation of the mythological dimension of the drivers behind return population flows. Also highlighted is a lack of consideration of structural factors in studies, most prominently socio-economic change, a factor which has special significance for present day return migrants in the Portuguese context