Johannes Kepler University of Linz

About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Computer science & Thin film. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

An adaptive multilevel approach to the minimal compliance problem in topology optimization

Abstract: This paper presents a new solution strategy for the minimal compliance problem in topology optimization. This problem contains the system of linear elasticity partial differential equations (PDEs) as a constraint resulting in a large scaled optimization problem after the finite element discretization. Due to the repeated solution of the direct field problem given by the PDE constraints, efficient solution techniques are required. In this paper we present a new solution method involving adaptive multilevel techniques combined with a multigrid approach for the direct problem. Topology optimization problems are ill-posed, so regularization is needed. In our algorithm we combine two regularization techniques, in fact filter methods, such that their disadvantages are eliminated and only their positive properties remain. Numerical experiments are performed with several benchmark problems, where our multilevel approach turns out to be quite efficient. For solving the optimization problems arising in each iteration step, the method of moving asymptotes is used. Copyright © 2005 John Wiley & Sons, Ltd.

Prekopa-Leindler type inequalities on Riemannian manifolds, Jacobi fields, and optimal transport

Abstract: We investigate Prekopa-Leindler type inequalities on a Riemannian manifold M equipped with a measure with density e V where the potential V and the Ricci curvature satisfy Hessx V + Ricx I for all x 2 M, with some 2 R. As in our earlier work (14), the argument uses optimal mass transport on M, but here, with a special emphasis on its connection with Jacobi fields. A key role will be played by the dierential equation satisfied by the determinant of a matrix of Jacobi fields. We also present applications of the method to logarithmic Sobolev inequalities (the Bakry-Emery criterion will be recovered) and to transport inequalities. A study of the displacement convexity of the entropy functional completes the exposition. Resume Nousl'extension d'inegalites de type Prekopa-Leindler au cas d'une variete riemannienne Mee d'une mesure ayant une densite e V ou le potentiel V et la courbure de Ricci verifient Hessx V + Ricx I (8x 2 M), pour un certain 2 R. Nous ferons appel, comme dans notre travail precedent (14), au transport optimal de mesure. Mais nous exploiterons plus encore son lien avec les champs de Jacobi, ce qui permettra de ramener la discussionl'´etude du determinant d'une matrice de champs de Jacobi. Nous presentonsd'autres applications de la methode, en particulier aux inegalites de Sobolev logarithmiques (critere de Bakry-

Post-mortem viral dynamics and tropism in COVID-19 patients in correlation with organ damage.

Abstract: The persistence of SARS-CoV-2 after death of infected individuals is unclear. The aim of this study was to investigate the presence of SARS-CoV-2 RNA in different organs in correlation with tissue damage and post-mortem viral dynamics in COVID-19 deceased. Twenty-eight patients (17 males, 11 females; age 66–96 years; mean 82.9, median 82.5 years) diagnosed with COVID-19 were studied. Swabs were taken post-mortem during autopsy (N = 19) from the throat, both lungs, intestine, gallbladder, and brain or without autopsy (N = 9) only from the throat. Selective amplification of target nucleic acid from the samples was achieved by using primers for ORF1a/b non-structural region and the structural protein envelope E-gene of the virus. The results of 125 post-mortem and 47 ante-mortem swabs were presented as cycle threshold (Ct) values and categorized as strong, moderate, and weak. Viral RNA was detected more frequently in the lungs and throat than in the intestine. Blood, bile, and the brain were negative. Consecutive throat swabs were positive up to 128 h after death without significant increase of Ct values. All lungs showed diffuse alveolar damage, thrombosis, and infarction and less frequently bronchopneumonia irrespective of Ct values. In 30% the intestine revealed focal ischemic changes. Nucleocapsid protein of SARS-CoV-2 was detected by immunohistochemistry in bronchial and intestinal epithelium, bronchial glands, and pneumocytes. In conclusion, viral RNA is still present several days after death, most frequently in the respiratory tract and associated with severe and fatal organ damage. Potential infectivity cannot be ruled out post-mortem.

Queries about social representation and construction

Abstract: L'A. porte son attention sur l'analyse des representations sociales. Ce type de perspective permet d'etudier aussi bien la connaissance scientifique que les conceptions communes. Il se demande en quoi une telle approche des representations sociales peut affecter la construction sociale de ces memes phenomenes. Il montre que le langage scientifique peut s'averer trompeur en ce domaine. Il s'efforce de savoir si les representations sociales constituent un objet veritable, si elle peuvent etre vraies ou fausses, si elles servent a la construction sociale de l'action