École normale supérieure de Cachan

About: École normale supérieure de Cachan is a education organization based out in Cachan, Île-de-France, France. It is known for research contribution in the topics: Decidability & Finite element method. The organization has 2717 authors who have published 5585 publications receiving 175925 citations.

Enumeration of first-order queries on classes of structures with bounded expansion

Abstract: We consider the evaluation of first-order queries over classes of databases with bounded expansion The notion of bounded expansion is fairly broad and generalizes bounded degree, bounded treewidth and exclusion of at least one minor It was known that over a class of databases with bounded expansion, first-order sentences could be evaluated in time linear in the size of the database We first give a different proof of this result Moreover, we show that answers to first-order queries can be enumerated with constant delay after a linear time preprocessing We also show that counting the number of answers to a query can be done in time linear in the size of the database

Elliptic general analytic solutions

Abstract: In order to flnd analytically the travelling waves of partially integrable au- tonomous nonlinear partial difierential equations, many methods have been pro- posed over the ages: \projective Riccati method", \tanh-method", \exponential method", \Jacobi expansion method", ew ...", etc. The common default to all these \truncation methods" is to only provide some solutions, not all of them. By implementing three classical results of Briot, Bouquet and Poincare, we present an algorithm able to provide in closed form all those travelling waves which are elliptic or degenerate elliptic, i.e. rational in one exponential or rational. Our examples here include the Kuramoto-Sivashinsky equation and the cubic and quintic complex Ginzburg-Landau equations.

++Spicy: an open-source tool for second-generation schema mapping and data exchange

Abstract: Recent results in schema-mapping and data-exchange research may be considered the starting point for a new generation of systems, capable of dealing with a significantly larger class of applications. In this paper we demonstrate the first of these second-generation systems, called ++Spicy. We introduce a number of scenarios from a variety of data management tasks, such as data fusion, data cleaning, and ETL, and show how, based on the system, schema mappings and data exchange techniques can be very effectively applied to these contexts. We compare ++Spicy to the previous generations of tools, to show that this is much-needed advancement in the field.

Upon Intranasal Vesicular Stomatitis Virus Infection, Astrocytes in the Olfactory Bulb Are Important Interferon Beta Producers That Protect from Lethal Encephalitis

Abstract: Previously we found that following intranasal (i.n.) infection with neurotropic vesicular stomatitis virus (VSV) type I interferon receptor (IFNAR) triggering of neuroectodermal cells was critically required to constrain intracerebral virus spread. To address whether locally active IFN-β was induced proximally, we studied spatiotemporal conditions of VSV-mediated IFN-β induction. To this end, we performed infection studies with IFN-β reporter mice. One day after intravenous (i.v.) VSV infection, luciferase induction was detected in lymph nodes. Upon i.n. infection, luciferase induction was discovered at similar sites with delayed kinetics, whereas on days 3 and 4 postinfection enhanced luciferase expression additionally was detected in the foreheads of reporter mice. A detailed analysis of cell type-specific IFN-β reporter mice revealed that within the olfactory bulb IFN-β was expressed by neuroectodermal cells, primarily by astrocytes and to a lesser extent by neurons. Importantly, locally induced type I IFN triggered distal parts of the brain as indicated by the analysis of ISRE-eGFP mice which after i.n. VSV infection showed enhanced green fluorescent protein (eGFP) expression throughout the brain. Compared to wild-type mice, IFN-β−/− mice showed increased mortality to i.n. VSV infection, whereas upon i.v. infection no such differences were detected highlighting the biological significance of intracerebrally expressed IFN-β. In conclusion, upon i.n. VSV instillation, IFN-β responses mounted by astrocytes within the olfactory bulb critically contribute to the antiviral defense by stimulating distal IFN-β-negative brain areas and thus arresting virus spread. IMPORTANCE The central nervous system has long been considered an immune privileged site. More recently, it became evident that specialized immune mechanisms are active within the brain to control pathogens. Previously, we showed that virus, which entered the brain via the olfactory route, was arrested within the olfactory bulb by a type I IFN-dependent mechanism. Since peripheral type I IFN would not readily cross the blood-brain barrier and within the brain thus far no abundant type I IFN responses have been detected, here we addressed from where locally active IFN originated from. We found that upon intranasal VSV instillation, primarily astrocytes, and to a lesser extent neurons, were stimulated within the olfactory bulb to mount IFN-β responses that also activated and protected distal brain areas. Our results are surprising because in other infection models astrocytes have not yet been identified as major type I IFN producers.

A performance evaluation of Azure and Nimbus clouds for scientific applications

Abstract: The emergence of cloud computing brought the opportunity to use large-scale computational infrastructures for a broad spectrum of scientific applications. As more and more cloud providers and technologies appear, scientists are faced with an increasingly difficult problem of evaluating various offerings, like public and private clouds, and deciding which model to use for their applications' needs. In this paper, we make a performance evaluation of two public and private cloud platforms for scientific computing workloads. We compare the Azure and Nimbus clouds, considering all the primary needs of scientific applications (computation power, storage, data transfers and costs). The evaluation is done using both synthetic benchmarks and a real-life application. Our results show that Nimbus incurs less varaibility and has increased support for data intensive applications, while Azure deploys faster and has a lower cost.