Normally and abnormally functioning left-sided porcine bioprosthetic valves after long-term implantation in patients: Distinct spectra of histologic and histochemical changes

This morphologic study (X-ray examination of gross specimens, histologic study and histochemical staining) compares two groups of explanted left-sided biopros-thetic valves: group 1,6 valves with normal cusp function and group II, 10 valves with significant dysfunction. Implantation periods ranged from 26 to 79 months. A computerized descriptive statistical method (principal component analysis) is used to analyze the qualitative results. Although qualitatively identical alterations are observed in both groups, the findings in the deep layers of the cusps of severe collagen breakdown, intensive fibrin penetration and various degrees of calcification are restricted to group II. Other findings of interest in both groups include amyloid deposits (four cases) and layering of fusiform host cells on the cusp surface (three cases).The computerized study shows that individuals of one clinical group are morphologically different from those of the other. Mechanical stress may contribute to surface alterations early after implantation, while further collagen breakdown and macrophagic activity result in deep penetration of plasma components and fibrin. Subsequent calcification is likely to be dystrophic rather than metabolic. Colonization of the cuspal surface by endothelial cells after long-term implantation of bioprosthetic valves expresses a new type of relation between host and bioprosthesis

Le partenariat au service de l’évaluation des projets d’éducation relative à l’environnement

Évaluer des projets d’éducation relative à l’environnement (ErE) avec tous les acteurs concernés et impliqués dans le projet, est-ce seulement une utopie de chercheurs ? À travers l’analyse de deux expériences, cet article cherche à démontrer la cohérence d’un partenariat dans l’évaluation de projets avec les objectifs poursuivis par l’ErE. Il précise le terme « partenariat », analyse les avantages vécus et précise les problèmes rencontrés lors d’évaluations menées à plusieurs selon les types de projets d’ErE et selon les moments de l’action. Un ensemble de questions est proposé, questions que tout praticien pourra se poser avant de se lancer dans une telle démarche aussi riche que complexe.Is it a researchers’ utopia to evaluate environmental education (EE) projects with all concerned and involved actors ? This paper, through the analysis of two experiences, aims to demonstrate the coherence of partnership in the evaluation of projects, with the pursuit of EE objectives. This paper also defines the term “partnership”, analyses the advantages experienced and details the problems encountered in evaluations conducted in a collaborative process, according to the types of EE projects and the moments of action. A series of questions is proposed which questions all practitioners may ask themselves before getting involved in such a rich and complex process

17 High-risk metastatic post-molar neoplasia complicating twin pregnancy with complete mole and coexisting fetus. Case report and review of the literature.

peer reviewe

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Shallow, Deep and Very Deep Cuts in the Analytic Center Cutting Plane Method

The analytic center cutting plane (ACCPM) methods aims to solve nondifferentiable convex problems. The technique consists of building an increasingly refined polyhedral approximation of the solution set. The linear inequalities that define the approximation are generated by an oracle as hyperplanes separating a query point from the solution set. In ACCPM, the query point is the analytic center, or an approximation of it, for the current polyhedral relaxation. A primal projective algorithm is used to recover feasibility and then centrality. In this paper we show that the cut does not need to go through the query point: it can be deep or shallow. The primal framework leads to a simple analysis of the potential variation, which shows that the inequality needed for convergence of the algorithm is in fact attained at the first iterate of the feasibility step. Keywords Projective algorithm, Analytic center, cutting plane method. This work has been completed with the support from the Fonds N..

Multiple Cuts in the Analytic Center Cutting Plane Method

We analyze the multiple cut generation scheme in the analytic center cutting plane method. We propose an optimal primal and dual updating direction when the cuts are central. The direction is optimal in the sense that it maximizes the product of the new dual slacks and of the new primal variables within the trust regions defined by Dikin&apos;s primal and dual ellipsoids. The new primal and dual directions use the variance--covariance matrix of the normals to the new cuts in the metric given by Dikin&apos;s ellipsoid. We prove that the recovery of a new analytic center from the optimal restoration direction can be done in O(p log(p + 1)) damped Newton steps, where p is the number of new cuts added by the oracle. The results and the proofs are independent of the specific scaling matrix ---primal, dual or primal-dual--- that is used in the computations. The computation of the optimal direction uses Newton&apos;s method applied to a self-concordant function of p variables. The convergence result of [20]..

Interior Points Methods for Nondifferentiable Optimization

We describe the analytice center cutting plane method and its relationship to classical methods of nondifferentiable optimization and column generations. Implementations issues are also discussed, and current applications liste

A Two-Cut Approach in the Analytic Center Cutting Plane Method

We analyze the two cut generation scheme in the analytic center cutting plane method. We propose an optimal updating direction when the two cuts are central. The direction is optimal in the sense that it maximizes the product of the new slacks within the trust region defined by Dikin&apos;s ellipsoid. We prove convergence in O ( n 2 &quot; 2 ) calls to the oracle and that the recovery of a new analytic center can be done in O(1) primal damped Newton steps. Keywords Primal Newton algorithm, Analytic center, Cutting Plane Method, Two cuts. This work has been completed with the support from the Fonds National Suisse de la Recherche Scientifique, grant 12-42503.94, from the Natural Sciences and Engineering Research Council of Canada, grant number OPG0004152 and from the FCAR of Quebec. GERAD/Faculty of Management, McGill University, 1001, Sherbrooke West, Montreal, Que., H3A 1G5, Canada. E-mail: [email protected]. LOGILAB/Management Studies, University of Geneva, 102, Bd Carl-Vogt,..

Multiple Cuts in the Analytic Center Cutting Plane Method

We analyze the multiple cut generation scheme in the analytic center cutting plane method. We propose an optimal primal and dual updating direction when the cuts are central. The direction is optimal in the sense that it maximizes the product of the new dual slacks and of the new primal variables within the trust regions defined by Dikin&apos;s primal and dual ellipsoids. The new primal and dual directions use the variance--covariance matrix of the normals to the new cuts in the metric given by Dikin&apos;s ellipsoid. We prove that the recovery of a new analytic center from the optimal restoration direction can be done in O(p log(p + 1)) damped Newton steps, where p is the number of new cuts added by the oracle, which may vary with the iteration. The results and the proofs are independent of the specific scaling matrix ---primal, dual or primal-dual--- that is used in the computations. The computation of the optimal direction uses Newton&apos;s method applied to a self-concordant function of p variab..