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Transit time ultrasound perivascular flow probe technology is superior to MR imaging on hepatic blood flow measurement in a porcine model

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Hepatobiliary & Pancreatic Diseases International 2018年第6期17卷 538-545页

作者： Mohamed Bekheit Chloe Audebert Petru Bucur Hans Adriaensen Emilie Bled Mylène Wartenberg Irene Vignon-Clementel Eric Vibert Inserm Unité 1193 112 Boulevard Paul Valliant CuturierVillejuifFrance Institute of medical sciences University of AberdeenAberdeenUK centre de recherche inria de paris ParisFrance Sorbonne Universités UPMC University of Paris 6Laboratoire Jacques-LouisLionsParisFrance CHRU hopitaux de ToursChirurgie Héato-biliaire et pancréatiqueTransplantation HéatiqueToursFrance Plateforme Chirurgie et Imagerie pour le recherche et l’Enseignement(CIRE) ImagerieUMR-PRC37380 NouzillyCentre INRA Val de LoireFrance AP-HP Hoital Paul BrousseCentre Héato-BiliaireVillejuifFrance

Background: The hepatic hemodynamics is an essential parameter in surgical planning as well as in various disease processes. The transit time ultrasound(TTUS) perivascular flow probe technology is widely used in clinical practice to evaluate the hepatic inflow, yet invasive. The phase-contrast-MRI(PC-MRI) is not invasive and potentially applicable in assessing the hepatic blood flow. In the present study, we compared the hepatic inflow rates using the PC-MRI and the TTUS probe, and evaluated their predictive value of post-hepatectomy adverse events. Methods: Eighteen large white pigs were anaesthetized for PC-MRI and approximately 75% hepatic resection was performed under a unified protocol. The blood flow was measured in the hepatic artery(Qha), the portal vein(Qpv), and the aorta above the celiac trunk(Qca) using PC-MRI, and was compared to the TTUS probe. The Bland-Altman method was conducted and a partial least squares regression(PLS) model was implemented. Results: The mean Qpv measured in PC-MRI was 0.55 ± 0.12 L/min, and in the TTUS probe was 0.74 ± 0.17 L/min. Qca was 1.40 ± 0.47 L/min in the PC-MRI and 2.00 ± 0.60 L/min in the TTUS probe. Qha was 0.17 ± 0.10 L/min in the PC-MRI, and 0.13 ± 0.06 L/min in the TTUS probe. The Bland-Altman method revealed that the estimated bias of Qca in the PC-MRI was 32%(95% CI:-49% to 15%); Qha 17%(95% CI:-15% to 51%); and Qpv 40%(95% CI:-62% to 18%). The TTUS probe had a higher weight in predicting adverse outcomes after 75% resection compared to the PC-MRI( β= 0.35 and 0.43 vs β = 0.22 and 0.07, for tissue changes and premature death, respectively). Conclusions: There is a tendency of the PC-MRI to underestimate the flow measured by the TTUS probes. The TTUS probe measures are more predictive of relevant post-hepatectomy outcomes.

关键词： Hepatic blood flow Phase contrast MRI Transit time ultrasound probe Porcine model Liver surgery

WTR:A Reputation Metric for Distributed Hash Tables Based on a Risk and Credibility Factor

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Journal of Computer Science & Technology 2009年第5期24卷 844-854页

作者： Xavier Bonnaire Erika Rosas departamento de Informatica Universidad Tecnica Federico Santa MariaValparaisoChile Laboratoire d'Informatique de paris 6 Universite Pierre et Marie CurieCNRS UMR 7606 INRIA REGALParisFrance

The growing number of popular peer to peer applications during the last five years has implied for researchers to focus on how to build trust in such very large scale distributed systems. Reputation systems have shown to be a very good solution to build trust in presence of malicious nodes. We propose in this paper a new metric for reputation systems on top of a Distributed Hash Table that uses a notion of risk to make the applications aware of certain behaviours of malicious nodes. We show that our metric is able to significantly reduce the number of malicious transactions, and that it also provides very strong resistance to several traditional attacks of reputations systems. We also show that our solution can easily scale, and can be adapted to various Distributed Hash Tables.

关键词： peer to peer reputation system risk evaluation

Transversal Instability for the Thermodiffusive Reaction-Diffusion System

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Chinese Annals of Mathematics,Series B 2015年第5期36卷 871-882页

作者： Michal KOWALCZYK Benoit PERTHAME Nicolas VAUCHELET departamento de Ingenieria Matematica and Centro de Modelamiento Matem'atico(UMI CNRS 2807) Universidad de Chile Sorbonne Universités UPMC Univ Paris 06UMR 7598Laboratoire Jacques-Louis LionsF-75005ParisFrance CNRS UMR 7598Laboratoire Jacques-Louis LionsF-75005ParisFrance inria-paris-Rocquencourt EPC MAMBADomaine de VoluceauBP10578153 Le Chesnay CedexFrance

The propagation of unstable interfaces is at the origin of remarkable patterns that are observed in various areas of science as chemical reactions, phase transitions, and growth of bacterial colonies. Since a scalar equation generates usually stable waves, the simplest mathematical description relies on two-by-two reaction-diffusion systems. The authors' interest is the extension of the Fisher/KPP equation to a two-species reaction which represents reactant concentration and temperature when used for flame propagation,and bacterial population and nutrient concentration when used in *** authors study circumstances in which instabilities can occur and in particular the effect of dimension. It is observed numerically that spherical waves can be unstable depending on the coefficients. A simpler mathematical framework is to study transversal instability, which means a one-dimensional wave propagating in two space ***, explicit analytical formulas give explicitely the range of paramaters for instability.

关键词： Traveling waves Stability analysis Reaction-diffusion equation Thermodiffusive system

A Review of Residual Distribution Schemes for Hyperbolic and Parabolic Problems:The July 2010 State of the Art

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Communications in Computational Physics 2012年第4期11卷 1043-1080页

作者： Remi Abgrall Team Bacchus Institut de Mathematiques de BordeauxINRIA and University of Bordeaux33405 Talence cedexFrance

We describe and review non oscillatory residual distribution schemes that are rather natural extension of high order finite volume schemes when a special emphasis is put on the structure of the computational *** provide their connections with standard stabilized finite element and discontinuous Galerkin schemes,show that their are really non *** also discuss the extension to these methods to parabolic *** also draw some research perspectives.

关键词： Hyperbolic problems Navier Stokes equations unstructuredmeshes residual distribution methods

Restricted Boltzmann machine: Recent advances and mean-field theory

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Chinese Physics B 2021年第4期30卷 1-24页

作者： Aurélien decelle Cyril Furtlehner departamento de Fìsica Téorica I Universidad Complutense28040 MadridSpain TAU team inria Saclay&LISN Universitéparis Saclay Orsay 91405France

This review deals with restricted Boltzmann machine(RBM) under the light of statistical *** RBM is a classical family of machine learning(ML) models which played a central role in the development of deep *** it as a spin glass model and exhibiting various links with other models of statistical physics,we gather recent results dealing with mean-field theory in this *** the functioning of the RBM can be analyzed via the phase diagrams obtained for various statistical ensembles of RBM,leading in particular to identify a compositional phase where a small number of features or modes are combined to form complex *** we discuss recent works either able to devise mean-field based learning algorithms;either able to reproduce generic aspects of the learning process from some ensemble dynamics equations or/and from linear stability arguments.

关键词： restricted Boltzmann machine(RBM) machine learning statistical physics

Numerical Analysis for an Energy-stable Total Discretization of a Poromechanics Model with Inf-sup Stability

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Acta Mathematicae Applicatae Sinica 2019年第1期35卷 28-53页

作者： B.BURTSCHELL P.MOIREAU D.CHAPELLE inria Université Paris-Saclay LMS Ecole PolytechniqueCNRS

We consider a previously proposed general nonlinear poromechanical formulation, and we derive a linearized version of this model. For this linearized model, we obtain an existence result and we propose a complete discretization strategy – in time and space – with a special concern for issues associated with incompressible or nearly-incompressible behavior. We provide a detailed mathematical analysis of this strategy,the main result being an error estimate uniform with respect to the compressibility parameter. We then illustrate our approach with detailed simulation results and we numerically investigate the importance of the assumptions made in the analysis, including the fulfillment of specific inf-sup conditions.

关键词： poromechanics incompressibility total discretization inf-sup energy estimates

Exploring system architectures in AADL via Polychrony and Syndex

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Frontiers of Computer Science 2013年第5期7卷 627-649页

作者： Huafeng YU Yue MA Thierry GAUTIER Loc BESNARD Jean-Pierre TALPIN Paul Le GUERNIC Yves SOREL inria Rennes-Bretagne Atlantique 263 av. du Général LeclercRennes 35042 France IRISA/CNRS 263 av. du Général LeclercRennes 35042 France inria paris-Rocquencourt Domaine de VoluceauBP 105Le Chesnay Cedex 78153 France

Architecture analysis&design language(AADL)has been increasingly adopted in the design of embedded systems,and corresponding scheduling and formal verification have been well ***,little work takes code distribution and architecture exploration into account,particularly considering clock constraints,for distributed multi-processor *** this paper,we present an overview of our approach to handle these concerns,together with the associated toolchain,***,in order to avoid semantic ambiguities of AADL,the polychronous/multiclock semantics of AADL,based on a polychronous model of computation,is *** synthesis is then carried out in Polychrony,which bridges the gap between the polychronous semantics and the synchronous semantics of *** same timing semantics is always preserved in order to ensure the correctness of the transformations between diferent *** distribution and corresponding scheduling is carried out on the obtained Syndex model in the last step,which enables the exploration of architectures originally specified in *** contribution provides a fast yet efcient architecture exploration approach for the design of distributed real-time and embedded *** avionic case study is used here to illustrate our approach.

关键词： Polychrony Signal AADL Syndex architecture exploration modeling timing analysis scheduling distribution

CONVERGENCE OF NUMERICAL SCHEMES FOR A CONSERVATION EQUATION WITH CONVECTION AND deGENERATE DIFFUSION

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Journal of Computational Mathematics 2021年第3期39卷 428-452页

作者： R.Eymard C.Guichard Xavier Lhebrard Universite Gustave Eiffel Laboratoire d'nalyse et de Mathematiques Appliquees(UMR 8050)UGEUPECCNRSF-77454Mame-la-ValleeFrance Sorbonne Universite Universite Paris-Diderot SPCCNRSInriaLaboratoire Jacques-Louis Lionsequipe ANGEF-75005 Paris Ecole Normale Superieure de Rennes France

The approximation of problems with linear convection and degenerate nonlinear difFusion,which arise in the framework of the transport of energy in porous media with thermodynamic transitions,is done usingθ-scheme based on the centred gradient discretisation *** convergence of the numerical scheme is proved,although the test functions which can be chosen are restricted by the weak regularity hypotheses on the convection field,owing to the application of a discrete Gronwall lemma and a general result for the time translate in the gradient discretisation *** numerical examples,using both the Control Volume Finite Element method and the Vertex Approximate Gradient scheme,show the role ofθfor stabilising the scheme.

关键词： Linear convection degenerate diffusion Gradient discretisation method θ-scheme

THE RANDOM BATCH METHOD FOR N-BODY QUANTUM DYNAMICS

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Journal of Computational Mathematics 2021年第6期39卷 897-922页

作者： Francois Golse Shi Jin Thierry Paul Ecole polytechnique CMLS91128 Palaiseau CedexFrance School of Mathematical Sciences Institute of Natural SciencesMOE-LSCShanghai Jiao Tong UniversityShanghai 200240China Sorbonne Universite CNRSUniversite de ParisINRIALaboratoire Jacques-Louis Lions75005 ParisFrance

This paper discusses a numerical method for computing the evolution of large interacting system of quantum *** idea of the random batch method is to replace the total interaction of each particle with the N−1 other particles by the interaction with p≪N particles chosen at random at each time step,multiplied by(N−1)/*** reduces the computational cost of computing the interaction potential per time step from O(N^(2))to O(N).For simplicity,we consider only in this work the case p=1—in other words,we assume that N is even,and that at each time step,the N particles are organized in N/2 pairs,with a random reshuffling of the pairs at the beginning of each time *** obtain a convergence estimate for the Wigner transform of the single-particle reduced density matrix of the particle system at time t that is both uniform in N>1 and independent of the Planck constant h̵.The key idea is to use a new type of distance on the set of quantum states that is reminiscent of the Wasserstein distance of exponent 1(or Monge-Kantorovich-Rubinstein distance)on the set of Borel probability measures on Rd used in the context of optimal transport.

关键词： Time-dependent Schrodinger equations Random batch method Mean-field limit Wasserstein distance