On the Optimal Control of a Class of Non-Newtonian Fluids

We consider optimal control problems of systems governed by stationary, incompressible generalized Navier-Stokes equations with shear dependent viscosity in a two-dimensional or three-dimensional domain. We study a general class of viscosity functions including shear-thinning and shear-thickening behavior. We prove an existence result for such class of optimal control problems

Existence of optimal boundary control for the Navier-Stokes equations with mixed boundary conditions

Variational approaches have been used successfully as a strategy to take advantage from real data measurements. In several applications, this approach gives a means to increase the accuracy of numerical simulations. In the particular case of fluid dynamics, it leads to optimal control problems with non standard cost functionals which, when constraint to the Navier-Stokes equations, require a non-standard theoretical frame to ensure the existence of solution. In this work, we prove the existence of solution for a class of such type of optimal control problems. Before doing that, we ensure the existence and uniqueness of solution for the 3D stationary Navier-Stokes equations, with mixed-boundary conditions, a particular type of boundary conditions very common in applications to biomedical problems

Improving Blood Flow Simulations Using Known Data

preprintNumerical simulations applied to blood flow together with the imaging processing advances are a powerful tool in the prevention and treatment of some diseases. The inclusion of real data in the numerical blood flow simulations allowsthe achievementofmore realistic and accurate results. In the literature, these techniques areknown asData Assimilation (DA)techniques.In this work we solve a variational DA problem to numerically reconstruct the blood flow circulation inside a real artery,deformed by a saccular aneurysm obtained from medical images and then importedto COMSOL Multiphysics®.We propose a weighted cost function that accurately recovers both the velocity and the wall shear stress profiles. The robustness of such cost function is tested with respect to different velocity inlet profilesinfo:eu-repo/semantics/submittedVersio

Aplicação de problemas de controlo a uma estenose idealizada

preprintNeste trabalho apresentamos, de forma sucinta, simulações numé-ricas de fluidos, de problemas do tipo Assimilação de Dados numa aborda-gem variacional. Apresentamos resultados aplicados à Hemodinâmica consi-derando uma geometria tridimensional na forma de uma estenose idealizadae recuperamos o perfil da velocidade do sangue nesta geometria.In this work, numerical simulations of fluids of Data Assimilationproblems in a variational approach are briefly presented. We obtain someresults applied to Hemodynamics in a 3D idealized stenosis and we recoverthe blood velocity profile in this geometry.info:eu-repo/semantics/submittedVersio

Optimal Control in Blood Flow Simulations

preprintBlood flow simulations can be improved by integrating known data into thenumerical simulations. Data assimilation techniques based on a variationalapproach play an important role in this issue. We propose a nonlinear optimalcontrol problem to reconstruct the blood flow profile from partial observationsof known data in idealized 2D stenosed vessels. The wall shear stress isincluded in the cost function, which is considered as an important indicatorfor medical purposes. To simplify we assume blood flow as an homogeneousfluid with non-Newtonian behavior. Using a Discretize then Optimize (DO)approach, we solve the nonlinear optimal control problem and we proposea weighted cost function that accurately recovers both the velocity and thewall shear stress profiles. The robustness of such cost function is tested withrespect to different velocity profiles and degrees of stenosis. The filteringeffect of the method is also confirmed. We conclude that this approach canbe successfully used in the 2D caseinfo:eu-repo/semantics/submittedVersio

A velocity tracking approach for the Data Assimilation problem in blood flow simulations

preprintSeveral advances have been made in Data Assimilation techniques applied to blood flow modeling. Typically,idealized boundary conditions, only verified in straight parts of the vessel, are assumed. We present ageneral approach, based on a Dirichlet boundary control problem, that may potentially be used in differentparts of the arterial system. The relevance of this method appears when computational reconstructions ofthe 3D domains, prone to be considered sufficiently extended, are either not possible, or desirable, due tocomputational costs. Based on taking a fully unknown velocity profile as the control, the approach uses adiscretize then optimize methodology to solve the control problem numerically. The methodology is appliedto a realistic 3D geometry representing a brain aneurysm. The results show that this DA approach may bepreferable to a pressure control strategy, and that it can significantly improve the accuracy associated totypical solutions obtained using idealized velocity profilesinfo:eu-repo/semantics/submittedVersio

Controle óptimo de fluidos não newtonianos

Dissertação para obtenção do Grau de Doutor em MatemáticaO estudo de problemas de controlo óptimo tem conhecido um crescente impulso na últimas décadas, motivado principalmente pelas aplicações que surgiram nas mais diversas áreas da engenharia. A necessidade de controlar sistemas dinâmicos e de obter objectivos pré-determinados usando controlos, foi o principal motor desta evolução. Em particular, a aplicação da teoria do controlo aos fluidos, tem sido alvo de grande interesse por parte dos investigadores na área. Este trabalho baseia-se no estudo de problemas de controlo óptimo de uma classe de fluidos não-Newtonianos, cuja viscosidade varia com a taxa de cisalhamento. Em primeiro lugar apresenta-se um conjunto de resultados teóricos relacionados com o estudo das equações de estado, do tipo sistemas de Navier-Stokes generalizados, no caso estacionário, e com a existência de solução para o problema de controlo para um fluido não-Newtoniano, incompressível regido por essas equações, assim como a dedução das condições de optimalidade de 1a ordem. Em segundo lugar, apresentam-se simulações numéricas de problemas de controlo do tipo "Assimilação de Dados" aplicados à Hemodinâmica, assunto de grande interesse em Biomedicina. Consideram-se geometrias bidimensionais e tridimensionais com interesse fisiológico, nomeadamente artérias com estenoses idealizadas, assim como uma artéria cerebral real em que se desenvolveu um aneurisma sacular. Através da resolução de problemas do tipo "Assimilação de Dados" na forma de problemas de controlo, o objectivo é obter soluções numéricas para os problemas propostos que coincidam, a menos de um determinado erro, com dados medidos em algumas partes do domínio, impondo um controlo do tipo Dirichlet na fronteira de entrada do fluido. Usando a abordagem "discretizar e em seguida optimizar" resolveu-se o problema de controlo óptimo cujo funcional de custo proposto é uma ponderação que consegue recuperar com precisão os perfis da velocidade e da tensão tangencial na parede da geometria.Fundação para a Ciência e Tecnologia - SFRH/BD/38326/2007 ; Projecto Optimization Methods in Continuum Mechanics, CMA/FCT.UNL PTDC/MAT/109973/200

Entrevistando professoras: o que elas falam sobre o ensino da argumentação?

Based on a socio-interacionistic approach of language teaching, we have focused in this article on how argumentative skills have been taught in Year 5 classrooms. Initially, 15 lessons from each teacher were observed in order to identify if any argumentative work took place in classroom activities. In this instance, a low investment in the development of argumentative skills was found. We have then interviewed those teachers in order to understand the conceptions which have guided their practices. Data indicated that teachers had diffi ulties to: identify text genders which were more suitable to improve argumentative skills; recognize specifi c argumentative skills which could be developed by students and plan diversifi ed lessons towards this topic. Despite this result, they recognized that argumentation teaching is important and clearly understood that students would be capable of developing argumentative skills if more favorable teaching conditions were applied.Key words: argumentation, teaching, text production, reading, orality.Com base na abordagem sociointeracionista de ensino de Língua, este artigo enfoca o trabalho didático com textos da ordem do argumentar em turmas do 5º ano do Ensino Fundamental. Foram realizadas inicialmente 15 observações de aula de cada docente,para verifi car se a argumentação era contemplada nas atividades realizadas em sala de aula. Observou-se que havia pouco trabalho didático voltado para o desenvolvimento de habilidades argumentativas. Foram, então, realizadas entrevistas para entender quais concepções sobre ensino da argumentação guiavam as práticas das docentes. A análise dos dados apontou que as professoras tinham difi culdades para: identifi car que gêneros textuais seriam indicados para o desenvolvimento de habilidades argumentativas; reconhecer que habilidades argumentativas poderiam ser desenvolvidas no trabalho pedagógico; e planejar aulas diversifi cadas com esse foco. Apesar disso, reconheciam a importância do ensino da argumentação e tinham clareza de que os estudantes seriam capazes de desenvolver tais habilidades, se as condições  didáticas fossem mais favoráveis.Palavras-chave: argumentação, ensino, produção de texto, leitura, oralidade

UTAustin | Portugal Workshop on Modeling and Simulations of Cardiovascular Diseases and Cancer

According to the most recent statistics, cardiovascular diseases and cancer are the major causes of death in developed countries, with a significant impact in the cost and overall status of healthcare. Understanding the fundamental mechanisms of the patho-physiology and treatment of these diseases are matters of the greatest importance around the world. This gives a key impulse to the progress in mathematical and numerical modeling of the associated complex phenomena governed by multiscale heterogeneous physical laws, integrating the knowledge of all their complex environmental, life style, ageing and genetic components into robust and fully reliable computer models and in silico settings. To face this challenge, the emerging integrative multidisciplinary research approach that involves interactions between different disciplines such as computational sciences, mathematics, biology and medicine is therefore of major significance. The final goal is to setup patient-specific models and simulations incorporating data and measurements taken from each single patient, that will be able to predict results of medical diagnosis and therapeutic planning with reasonable accuracy and using non-invasive means. This is a CoLab Workshop organized as an initiative of the UT Austin | Portugal Program that follows a series of events to reinforce the Portuguese competences in Computational Medicine and Biomathematics. The Workshop provides a place to exchange recent developments, discoveries and progresses in this challenging research field. The main goal is to bring together doctoral candidates, postdoctoral scientists and graduates interested in the field, giving them the opportunity to make scientific interactions and new connections with established experts in the interdisciplinary topics covered by the event, including medical researchers. Another important goal of the Workshop is to promote collaboration between members of the different areas of the UT Austin | Portugal community

Análise comparativa entre osteossarcoma e sarcoma de Ewing: avaliação do intervalo de tempo entre o início dos sinais e sintomas e o diagnóstico

OBJECTIVE: The purposes of this study were to describe the early signs and symptoms of osteosarcoma and Ewing's sarcoma, identify symptoms that could be used to help differentiate the two types of tumors, and determine the time elapsed between the onset of signs and symptoms and the definitive diagnosis in our service, providing information and imputus for earlier diagnosis of these tumors. METHODS: A retrospective analysis of the medical dossiers of 365 patients under 30 years of age diagnosed with osteosarcoma or Ewing's sarcoma was performed, and the aspects of the clinical diagnosis were statistically analyzed and compared. RESULTS: The time between the onset of signs and the symptoms was 5.25 months for osteosarcoma and 8.1 months for Ewing's sarcoma, and the most frequent (89.5%) early symptom of osteosarcoma and Ewing's sarcoma was local pain. Symptoms that might aid diagnosis included early local volume increase and the presence of fever. CONCLUSION: The time until diagnosis of both neoplasias was higher than that reported for North America and Europe. Education of the lay public and medical professionals regarding suspicious early signs and symptoms might shorten the delay of diagnosis.FINALIDADE: Eeste estudo propõ-se a esclarecer as características do osteossarcoma e do sarcoma de Ewing, bem como definir o intervalo de tempo decorrido, no Brasil, entre o início dos sinais e dos sintomas e o diagnóstico definitivo, fornecendo subsídios para um diagnóstico precoce desses tumores. MÉTODO: Alguns aspectos dos diagnósticos clínicos do prontuário de 365 pacientes com menos de 30 anos de idade, portadores de osteossarcoma ou sarcoma de Ewing foram analisados de forma retrospectiva e comparativa, seguindo-se uma análise estatística. RESULTADOS: O tempo entre o início de sinais e sintomas e o diagnóstico foi de 5,25 meses no osteossarcoma e 8,1 meses no sarcoma de Ewing; o sintoma mais freqüente (89,5) nas duas neoplasias foi a dor localizada. CONCLUSÃO: O tempo para o diagnóstico de ambas as neoplasias é maior do que o observado em estatísticas norte-americanas e européias