Strategies for processing images with 4D-Var data assimilation methods

Data Assimilation is a well-known mathematical technic used, in environmental sciences, to improve, thanks to observation data, the forecasts obtained by meteorological, oceanographic or air quality simulation models. It aims to solve the evolution equations, describing the dynamics of the state variables, and an observation equation, linking at each space-time location the state vector and the observations. Data Assimilation allows to get a better knowledge of the actual system's state, named the reference. In this article, we first describe various strategies that can be applied in the framework of variational data assimilation to study various image processing issues. Second, we detail the mathematical setting and the analysis of pros and cons of each strategy for the issue of motion estimation. Last, results are provided on synthetic images and satellite acquisitions.L'assimilation de données est un outil largement utilisé dans les sciences de l'environnement pour améliorer, au moyen de données d'observation, les prédictions obtenues par les modèles de simulation. Elle s'applique en météorologie, en océanographie et en qualité de l'air, par exemple. L'assimilation de données permet de résoudre les équations d'évolution, décrivant la dynamique des variables d'état du modèle, et les équations d'observation, qui lient le vecteur d'état et les observations. Dans cet article, nous décrivons plusieurs stratégies d'assimilation d'images, dans le contexte de la formulation faible de l'assimilation variationnelle. Nous détaillons ensuite les équations mathématiques de ces stratégies et nous analysons leurs avantages et défauts respectifs pour une application à l'estimation du mouvement. Des résultats sont fournis sur des données synthétiques et des images satellite

Virtue in client centred care : a philosophical investigation of virtue and nursing in Canadian healthcare

Part of the mandate of the Canadian Nursing Association is to develop and maintain a 'code of ethics'. Provincial professional nursing associations have largely based their own ethical frameworks on this code. However, as Mitchell and Benner have argued, ethical codes fail to capture some essential elements of the ethical life of nurses. This signals a need for a more accurate and experience based ethical framework for nurses. One such attempt is a document published by the Registered Nurses Association of Ontario entitled 'Client Centred Care' that presents an ethical framework that relies on a nurses' practical wisdom and that emphasizes individual experiences of ethical situations based on close relationships with patients. Some traditional ethical frameworks in the philosophical field have come under attack by Neo-Aristotelian Virtue Ethicists for the same reasons. These philosophers, including Wiggins, Maclntyre, Hursthouse, Zagzebski, and MacDowell, have supplemented unsatisfactory, traditional ethical frameworks with one that emphasizes perception of salience, practical wisdom, and practice. Because they are similar in their approaches to ethical life, and in their criticisms of traditional ethical frameworks, 'Client Centred Care' lends itself well to the vocabulary and conceptual structure of Virtue Ethics. However, for all its merits, 'Client Centred Care' does not provide us with the rigor of a serious ethical text, leaving terms inadequately defined and many questions unanswered. This work is an effort to clarify the ethical claims of this text through the lens of Virtue Ethics. In doing so, I will expose some of the deficiencies of this ethical framework for nurses and propose a curative solution by examining the work of Narrative Ethicists such as Martha Nussbaum

Les stratégies d'adaptation des filles victimes d'agression sexuelle : influences parentales et familiales

Les taux de prévalence et d'incidence des agressions sexuelles ainsi que leurs multiples conséquences justifient les nombreuses études portant sur cette problématique. Ainsi, plusieurs s'intéressent aux variables qui favorisent le meilleur ajustement possible des victimes. Parmi ces variables, les stratégies d'adaptation ressortent comme ayant un impact significatif. Le présent mémoire s ‘insère dans ce courant de recherche afin de mettre en lumière les mécanismes qui favorisent l'émergence de stratégies d'adaptation efficaces. Les variables liées au contexte familial et aux stratégies utilisées par les parents sont rapportées comme pouvant influencer les stratégies adoptées par les jeunes. Les stratégies d'adaptation de 90 victimes d'agression sexuelle, celles de leur parent ainsi que Sa qualité de l'environnement familial ont été analysées afin de déterminer dans quelle mesure les stratégies d'adaptation des filles victimes d'agression sexuelle sont en lien avec les stratégies d'adaptation de leurs parents. Les résultats indiquent que les stratégies utilisées par le parent ainsi que la qualité de l'environnement familial sont liées à l'utilisation de certaines stratégies dont la recherche de soutien social, la cote globale des stratégies d'approche, l'externalisation et l'évitement

Total laparoscopic abdominal aortic aneurysm repair with reimplantation of the inferior mesenteric artery

AbstractWe performed a total laparoscopic reimplantation of the inferior mesenteric artery (IMA) during laparoscopic infrarenal aortic aneurysm repair. The postoperative course was uneventful, and angiograms showed a patent IMA after reimplantation. To our knowledge, total laparoscopic reimplantation of the IMA in human beings has not previously been described

Association between disruption of CD4 receptor dimerization and increased human immunodeficiency virus type 1 entry

BACKGROUND: Human immunodeficiency virus (HIV) enters target cells by a membrane fusion process that involves a series of sequential interactions between its envelope glycoproteins, the CD4 receptor and CXCR4/CCR5 coreceptors. CD4 molecules are expressed at the cell surface of lymphocytes and monocytes mainly as monomers, but basal levels of CD4 dimers are also present at the cell surface of these cells. Previous evidence indicates that the membrane distal and proximal extracellular domains of CD4, respectively D1 and D4, are involved in receptor dimerization. RESULTS: Here, we have used A201 cell lines expressing two CD4 mutants, CD4-E91K, E92K (D1 mutant) and CD4-Q344E (D4 mutant), harboring dimerization defects to analyze the role of CD4 dimerization in HIV-1 entry. Using entry assays based on β-lactamase-Vpr or luciferase reporter activities, as well as virus encoding envelope glycoproteins derived from primary or laboratory-adapted strains, we obtained evidence suggesting an association between disruption of CD4 dimerization and increased viral entry efficiency. CONCLUSION: Taken together, our results suggest that monomeric forms of CD4 are preferentially used by HIV-1 to gain entry into target cells, thus implying that the dimer/monomer ratio at the cell surface of HIV-1 target cells may modulate the efficiency of HIV-1 entry

White matter multi-resolution segmentation using fuzzy set theory

International audienceThe neural architecture of the white matter of the brain, obtained using tractography algorithms, can be divided into different tracts. Their function is, in many cases, still an object of study and might be affected in some syndromes or conditions. Obtaining a reproducible and correct segmentation is therefore crucial both in clinics and in research. However, it is difficult to obtain due to the huge number of fibers and high inter-subject variability. In this paper, we propose to segment and recognize tracts by directly modeling their anatomical definitions, which are usually based on relationships between structures. Since these definitions are mainly qualitative, we propose to model their intrinsic vagueness using fuzzy spatial relations and combine them into a single quantitative score mapped to each fiber. To cope with the high redundancy of tractograms and ease interpretation , we also take advantage of a simplification scheme based on a multi-resolution representation. This allows for an interactive and real-time navigation through different levels of detail. We illustrate our method using the Human Connectome Project dataset and compare it to other well-known white matter segmentation techniques