Condensation of helium in aerogels and athermal dynamics of the Random Field Ising Model

High resolution measurements reveal that condensation isotherms of $^4$He in a silica aerogel become discontinuous below a critical temperature. We show that this behaviour does not correspond to an equilibrium phase transition modified by the disorder induced by the aerogel structure, but to the disorder-driven critical point predicted for the athermal out-of-equilibrium dynamics of the Random Field Ising Model. Our results evidence the key role of non-equilibrium effects in the phase transitions of disordered systems.Comment: 5 p + suppl. materia

Critical behavior of the liquid gas transition of 4 He confined in a silica aerogel

6 pagesInternational audienceWe have studied 4 He confined in a 95% porosity silica aerogel in the vicinity of the bulk liquid gas critical point. Both thermodynamic measurements and light scattering experiments were performed to probe the effect of a quenched disorder on the liquid gas transition, in relation with the Random Field Ising Model (RFIM). We find that the hysteresis between condensation and evaporation present at lower temperatures disappears at a temperature T ch between 25 and 30 mK below the critical point. Slow relaxations are observed for temperatures slightly below T ch , indicating that some energy barriers, but not all, can be overcome. Above T ch , no density step is observed along the (reversible) isotherms, showing that the critical behavior of the equilibrium phase transition in presence of disorder, if it exists, is shifted to smaller temperatures, where it cannot be observed due to the impossibility to reach equilibrium. Above T ch , light scattering exhibits a weak maximum close to the pressure where the isotherm slope is maximal. This behavior can be accounted for by a simple model incorporating the compression of 4 He close to the silica strands

Rapid prototyping of complete systems, the case study of a smart parking

International audienceThis paper details how LINC a coordination middle-ware, can fasten the development of prototypes that integrate several equipment. A case study of rapid prototyping is presented. It illustrates how a smart parking prototype has been built from several independent and autonomous equipment, coming from different vendors. This has been achieved by parallel development thanks to the resource based approach offered by LINC. This paper also describes how LINC helps building rich user interfaces quickly and easily. I. INTRODUCTION Embedded systems have been part of our daily life for decades. Most of the industrial or consumer products embed multiple processors, sensors and actuators. The next step is the opportunity to build new products, systems, and usages, combining together several of these products. In such innovative and quickly evolving context it is necessary to build prototypes to test, validate, and challenge new products usages or solutions. This paper considers prototypes including several equipment, possibly from different vendors. Such prototypes can be used to exhibit demonstrations in a trade fair, to convince investors of the viability of an idea or to verify the adequacy of the solutions for early adopters. To succeed in today's highly competitive market, a prototype should be more than a few items wired together with a command line interface. Targeted prototypes are real-life demonstrations of new products or technologies with a high end-user experience. Moreover, a prototype should be included in its targeted environment (e.g. a house, a building or a parking). The development of prototypes is vital during the validation stage of new products as they may help to

Towards Large-Mode-Area fibers fabricated by the full vapor-phase SPCVD process

International audienceLarge-Mode-Area (LMA) fibers are key elements in modern high power fiber lasers operating at 1 µm. LMA fibers are highly ytterbium-doped and require a fine control of the core refractive index (RI) close to the silica level. These low RI have been achieved with multi-component materials elaborated using a full-vapor phase Surface Plasma Chemical Vapor Deposition (SPCVD) process, enabling the fabrication of large core diameter preforms (up to 4 millimeters). Following the technology demonstration, presented in Photonics West 2017, with results on 10/130 (core-to-clad diameters (in µm) ratio) fibers, this paper aims to present updated results obtained for double-clad 11/130, 20/130 and 20/400 LMA fibers, with numerical apertures at, respectively, 0.08 and 0.065. The study is based on aluminosilicate core material co-doped either with fluorine or phosphorus to achieve optimal radial RI tailoring. The fiber produced exhibit low background losses (<20dB/km at 1100nm) and high power conversion efficiencies, up to 74% for output powers of 100W limited by our test setup. The Gaussian beam quality has been evaluated using the M² measurement. Photodarkening behavior will be discussed for both fluorine and phosphorus-doped aluminosilicate materials and particularly the use of cerium as co-dopant. The SPCVD technology can indeed be used for the production of Yb-doped LMA fibers. Current development is now focused on other rare-earth doped fibers

A statistically inferred microRNA network identifies breast cancer target miR-940 as an actin cytoskeleton regulator

International audienceMiRNAs are key regulators of gene expression. By binding to many genes, they create a complex network of gene co-regulation. Here, using a network-based approach, we identified miRNA hub groups by their close connections and common targets. In one cluster containing three miRNAs, miR-612, miR-661 and miR-940, the annotated functions of the co-regulated genes suggested a role in small GTPase signalling. Although the three members of this cluster targeted the same subset of predicted genes, we showed that their overexpression impacted cell fates differently. miR-661 demonstrated enhanced phosphorylation of myosin II and an increase in cell invasion, indicating a possible oncogenic miRNA. On the contrary, miR-612 and miR-940 inhibit phosphorylation of myosin II and cell invasion. Finally, expression profiling in human breast tissues showed that miR-940 was consistently downregulated in breast cancer tissues M icroRNAs are a class of endogenous, small (19–25 nucleotides), single-stranded non-coding RNAs that regulate gene expression in all eukaryotic organisms. In metazoans, microRNAs most commonly bind to the 39 untranslated region (39UTR) of their mRNA target transcript and cause translational repression and/or mRNA degradation. Every microRNA is predicted to regulate from a dozen to thousands of genes, including transcription factors. This fine-tuning of protein expression is known to be involved in many physiological processes, such as development, apoptosis, signal transduction and even cancer progression 1,2. More than 2,000 mature human microRNAs are listed in the 20 th release of miRBase: http://www.mirbase.org (2014) (Date of access:19/08/2013), and some authors hypothesise that the majority of human genes are regulated by microRNAs 3. Since their discovery in 1993 4 , a fair understanding of their role in animal development and in the onset and progression of diseases 2 , as well as of their potential use in therapies 5 , has been gathered. However, the cooperative behaviour of microRNAs is still under investigation. A growing body of experimental evidence suggests that microRNAs can regulate genes through complementarity, meaning that microRNAs can act together to regulate individual genes or groups of genes involved in similar processes 6. For example, Hu and co-workers demonstrated that transducing a cocktail of precursor microRNAs (miR-21, miR-24 and miR-221) can result in more effective engraftment of transplanted cardiac progenitor cells 7. Consistent with these discoveries, Zhu et al. demonstrated that miR-21 and miR-221 coregulate 56 gene ontology (GO) processes 8. In the same study, the authors also showed that cotransfection of miR-1 and miR-21 increases H 2 O 2-induced myocardial apoptosis and oxidative stress. These recent findings support the idea of microRNA-mediated cooperative regulation but also argue for the use of systemic approaches, notably based on graph theory, to decipher individual and complementary roles of microRNAs. Some work has been conducted to use recent high-throughput experiment-derived data sets to infer microRNA synergistic relationships 9–12. Herein, we present a microRNA network based on target similarities among microRNAs to infer clusters of microRNAs. Clusters are defined as groups of microRNAs sharing a set of common targets, predicted by either DIANA-microT v3 13 or TargetScan v6.2 14. Some authors have used GO enrichment analysis as a confirmatory tool for their clustering approach 11. In our case, GO enrichment is not used to infer networks but as a way to estimate the probable metabolic pathway(s) a cluster of microRNAs could co-regulate. Moreover, the novelty of our approach is to consider not only clusters of microRNAs but also OPE

Review of small-angle coronagraphic techniques in the wake of ground-based second-generation adaptive optics systems

Small-angle coronagraphy is technically and scientifically appealing because it enables the use of smaller telescopes, allows covering wider wavelength ranges, and potentially increases the yield and completeness of circumstellar environment - exoplanets and disks - detection and characterization campaigns. However, opening up this new parameter space is challenging. Here we will review the four posts of high contrast imaging and their intricate interactions at very small angles (within the first 4 resolution elements from the star). The four posts are: choice of coronagraph, optimized wavefront control, observing strategy, and post-processing methods. After detailing each of the four foundations, we will present the lessons learned from the 10+ years of operations of zeroth and first-generation adaptive optics systems. We will then tentatively show how informative the current integration of second-generation adaptive optics system is, and which lessons can already be drawn from this fresh experience. Then, we will review the current state of the art, by presenting world record contrasts obtained in the framework of technological demonstrations for space-based exoplanet imaging and characterization mission concepts. Finally, we will conclude by emphasizing the importance of the cross-breeding between techniques developed for both ground-based and space-based projects, which is relevant for future high contrast imaging instruments and facilities in space or on the ground.Comment: 21 pages, 7 figure

A survey of IoT protocols and their security issues through the lens of a generic IoT stack

International audienceThe Internet of things (IoT) is rapidly growing, and many security issues relate to its wireless technology. These security issues are challenging because IoT protocols are heterogeneous, suit different needs, and are used in different application domains. From this assessment, we identify the need to provide a homogeneous formalism applying to every IoT protocols. In this survey, we describe a generic approach with twofold challenges. The first challenge we tackle is the identification of common principles to define a generic approach to compare IoT protocol stack. We base the comparison on five different criteria: the range, the openness of the protocol, the interoperability, the topology and the security practices of these IoT protocols. The second challenge we consider is to find a generic way to describe fundamental IoT attacks regardless of the protocol used. This approach exposes similar attacks amongst different IoT protocols and is divided into three parts: attacks focusing on packets (passive and active cryptographic attacks), attacks focusing on the protocol (MITM, Flooding, Sybil, Spoofing, Wormhole attacks) and attacks focusing on the whole system (Sinkhole, Selective forwarding attacks). It also highlights which mechanisms are different between two protocols to make both of them vulnerable to an attack. Finally, we draw some lessons and perspectives from this transversal study

Audit d'un système IoT par test d'intrusion

National audienceL'explosion du secteur de l'Internet des Objets, reposant majoritairement sur des technologies de communication sans fil, soulève de nombreuses problématiques de sécurité. Ceci est notamment dû à leur caractère hétérogène, à leurs réseaux peu cloisonnés et une mise sur le marché hâtive. Nous proposons dans le cadre de cette thèse une méthode permettant d'évaluer la sécurité d'un système d'objets connectés utilisant des modes de communication sans fil, ceci afin de renforcer la sécurité du système d'information dans son ensemble. Notre méthodologie se base sur une approche éprouvée dans l'IT classique : le test d'intrusion

IoTMap: A protocol-agnostic multi-layer system to detect application patterns in IoT networks

International audienceThe growth of the Internet of Things (IoT) results in a proliferation of different protocols (ZigBee, Bluetooth, 6LowPAN, Z-Wave, Wi-Fi, etc.). Organizations tend to quickly deploy several IoT applications over time and thus face heterogeneous IoT systems, combining different IoT protocols in different places of the overall system. This heterogeneity of protocols makes these networks hard to monitor or control, and some misconfigurations or unexpected device behaviours may even expose users to security issues. In this work, we propose the IoTMap system. IoTMap models interconnected and heterogeneous IoT networks, combining different protocols, by providing a generic stack and a unified packet format. IoTMap builds an iterative graph model where high-level semantics can progressively be deduced, ranging from packet transmission to application-type analysis. As such, IoTMap detects application behaviours amongst devices implementing different protocols, interconnected through a multi-protocol hub. In its current implementation (available at https://github.com/AlgoSecure/iotmap), IoTMap can inspect Zig- Bee, BLE and 6LowPAN networks