Experimenting with Gnutella Communities

Computer networks and distributed systems in general may be regarded as communities where the individual components, be they entire systems, application software or users, interact in a shared environment. Such communities dynamically evolve with components or nodes joning and leaving the system. Their own individual activities affect the community's behaviour and vice-versa. This paper discusses various experiments undertaken to investigate the behaviour of a real system, the Gnutella network, which represents such a community. Gnutella is a distributed Peer-to-Peer data-sharing system without any central control. It turns out that most interactions between nodes do not last long and much of their activity is devoted to finding appropriate partners in the network. Good connections lasting longer appear only as rare events. For example, out of 42,000 connections only 57 hosts were found to available on a regular basis. This means that, in contrast to the common belief that this kind of peer-to-peer networks or sub-communities are always large, they are actually quite small. However, those sub-communities examplify very dynamic behaviour because their actual composition can change very quickly. The experimental results presented have been obtained from a Java implementation of Gnutella running in the open Internet environment, and thus in unknown and quickly changing network structures heavily dependent on chance. Les réseaux informatique ainsi que les systèmes distribués peuvent être considérés comme des communautés où les composantes - que ce soit des systèmes complets, des programmes ou des usagers - interagissent dans un environnement partagé. Ces communautés sont dynamiques car des éléments peuvent s'y joindre ou quitter en tout temps. L'article présente les résultats d'une suite d'expériences et de mesures faites sur Gnutella, un système peer-to-peer à grande échelle qui opère sans aucun contrôle centralisé. Nous avons remarqué qu'une grande partie des messages échangés sont erronés ou redondants et que les interactions entre n?uds ne durent pas très longtemps. En particulier, des connexions durant plus d'une minute sont des phénomènes rares. Les n?uds passent donc la majorité de leur temps à remplacer les partenaires perdus et, contrairement à l'idée répandue que les réseaux peer-to-peer sont immenses, nous avons noté que les communautés effectives étaient assez limitées. Gnutella est un environnement très dynamique avec peu de stabilité. Par exemple, de 42,000 sites avec lesquels nous avons établi une connexion, il a seulement été possible de re-communiquer de façon régulière avec 57. Dans un tel environnement, la chance joue un rôle important dans la performance observée; mais nous avons élaboré un protocole expérimental permettant de comparer diverses options.Gnutella, peer-to-peer networks, Internet communities, distributed systems, protocols, Gnutella, réseaux peer-to-peer, communautés virtuelles, internet, systèmes distribués, protocoles de télécommunication

3D advanced integration technology for heterogeneous systems

International audience3D integration technology is nowadays mature enough, offering today further system integration using heterogeneous technologies, with already many different industrial successes (Imagers, 2.5D Interposers, 3D Memory Cube, etc.). CEA-LETI has been developing for a decade 3D integration, and have pursued research in both directions: developing advanced 3D technology bricks (TSVs, µ-bumps, Hybrid Bonding, etc), and designing advanced 3D circuits as pioneer prototypes. In this paper, a short overview of some recent advanced 3D technology results is presented, including some latest 3D circuit's description

RODIN project, Topology Optimization 2.0?

RODIN project is an attempt to propose a new kind of topology optimization tools. It has been motivated by the combination of two events: (1) the industrials demands for getting past serious limits identified in the available tools, (2) the advent of a new mathematical approach in the mid 2000's presenting very interesting properties. This project has been launched in July 2012 and is supported by French public funding. It is a collaborative project that gathers ten partners (ranging from academics to software editors and industrials end-users) and firmly aims at overcoming technical and scientific locks in the area of topology optimization. RODIN is therefore an ambitious and risky project that will possibly mark the birth of a new numerical tool

GWAS in the SIGNAL/PHARE clinical cohort restricts the association between the FGFR2 locus and estrogen receptor status to HER2-negative breast cancer patients

International audienceGenetic polymorphisms are associated with breast cancer risk. Clinical and epidemiological observations suggest that clinical characteristics of breast cancer, such as estrogen receptor or HER2 status, are also influenced by hereditary factors. To identify genetic variants associated with pathological characteristics of breast cancer patients, a Genome Wide Association Study was performed in a cohort of 9365 women from the French nationwide SIGNAL/PHARE studies (NCT00381901/RECF1098). Strong association between the FGFR2 locus and ER status of breast cancer patients was observed (ER-positive n=6211, ER-negative n=2516; rs3135718 OR=1.34 p=5.46x10-12). This association was limited to patients with HER2-negative tumors (ER-positive n=4267, ER-negative n=1185; rs3135724 OR=1.85 p=1.16x10-11). The FGFR2 locus is known to be associated with breast cancer risk. This study provides sound evidence for an association between variants in the FGFR2 locus and ER status among breast cancer patients, particularly among patients with HER2-negative disease. This refinement of the association between FGFR2 variants and ER-status to HER2-negative disease provides novel insight to potential biological and clinical influence of genetic polymorphisms on breast tumors

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Experimenting with Gnutella Communities

Computer networks or distributed systems in general may be regarded as communities where the individual components, be they entire systems, application software or users, interact in a shared environment. Such communities dynamically evolve with components or nodes joining and leaving the system

Eryloside W, a triterpenoid saponin from the sponge Dictyonella marsilii

International audienceA new saponin derivative named eryloside W was isolated from the marine sponge Dictyonella marsilii (Demospongiae, Halichondrida, Dictyonellidae). The structure of the compound was elucidated through extensive use of 1D and 2D nuclear magnetic resonance and mass spectrometry. Determination of the absolute configuration was performed using electronic circular dichroism (ECD) by comparison of experimental and time dependent density functional theory (TDDFT) calculated spectra. This is the first occurrence of a saponin derivative produced by a marine sponge present in the Mediterranean. (C) 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing

HARMONI at ELT: Full scale prototype of the laser guide star wavefront sensor

International audienceHARMONI is the first light visible and near-IR integral field spectrograph for the ELT. It covers a large spectral range from 450 nm to 2450 nm with resolving powers from 3500 to 18000 and spatial sampling from 60 mas to 4 mas. It can operate in two Adaptive Optics modes-SCAO (including a High Contrast capability) and LTAO-or with no AO mode. To prepare the final design reviews, we have built an optical bench to emulate and characterize the performance of the laser guide star (LGS) wavefront sensor (WFS) to be used in HARMONI. The WFS is a classic Shack-Hartmann, nonetheless pushed to the extreme due to the size of the primary mirror of the ELT (39 m). The WFS is composed of a 80 × 80 double side microlens array (MLA), an optical relay made of 6 lenses in order to re-image the light coming from the MLA on the detector, and a CMOS camera using a Sony detector with 1608 × 1104 pixels, RON< 3e, and a frame rate of 500Hz. The sensor has a large number of pixels to provide a field-of-view wider than 15 arcsec per subaperture over the full pupil, which is required to image the elongated LGS spots. An innovative feature of our bench is the use of a spatial light modulator (SLM) which allows us to emulate the M4 deformable mirror (DM) and the real position of its actuators, together with the projected spiders in the pupil plane. We report on the design and performance of our bench, including the first interaction matrices using the ELT-M4 influence functions and a non-elongated source. We expect to implement a system to emulate an elongated source in order to grasp a better understanding of its effects on wavefront sensing