Multi-layer model for the web graph

This paper studies stochastic graph models of the WebGraph. We present a new model that describes the WebGraph as an ensemble of different regions generated by independent stochastic processes (in the spirit of a recent paper by Dill et al. [VLDB 2001]). Models such as the Copying Model [17] and Evolving Networks Model [3] are simulated and compared on several relevant measures such as degree and clique distribution

Extremal polynomials in stratified groups

We introduce a family of extremal polynomials associated with the prolongation of a stratified nilpotent Lie algebra. These polynomials tre related to a new algebraic characterization of abnormal sub-Riemannian extremals in stratified nilpotent Lie groups. They satisfy a set of remarkable structure relations that are used to integrate the adjoint equations, in both normal and abnormal case

A cooperative Top-Down/Bottom-Up Technique for Motion Field Segmentation

The segmentation of video sequences into regions underlying a coherent motion is one of the most useful processing for video analysis and coding. In this paper, we propose an algorithm that exploits the advantages of both top-down and bottom-up techniques for motion eld segmentation. To remove camera motion, a global motion estimation and compensation is rst performed. Local motion estimation is then carried out relying on a traslational motion model. Starting from this motion eld, a two-stage analysis based on ane models takes place. In the rst stage, using a top-down segmentation technique, macro-regions with coherent ane motion are extracted. In the second stage, the segmentation of each macro-region is rened using a bottom-up approach based on a motion vector clustering. In order to further improve the accuracy of the spatio-temporal segmentation, a Markov Random Field (MRF)-inspired motion-and-intensity based renement step is performed to adjust objects boundaries

Budget Feasible Mechanisms on Matroids

Motivated by many practical applications, in this paper we study budget feasible mechanisms with the goal of procuring an independent set of a matroid. More specifically, we are given a matroid M= (E, I). Each element of the ground set E is controlled by a selfish agent and the cost of the element is private information of the agent itself. A budget limited buyer has additive valuations over the elements of E. The goal is to design an incentive compatible budget feasible mechanism which procures an independent set of the matroid of largest possible value. We also consider the more general case of the pair M= (E, I) satisfying only the hereditary property. This includes matroids as well as matroid intersection. We show that, given a polynomial time deterministic algorithm that returns an α-approximation to the problem of finding a maximum-value independent set in M, there exists an individually rational, truthful and budget feasible mechanism which is (3 α+ 1) -approximated and runs in polynomial time, thus yielding also a 4-approximation for the special case of matroids

Ultrathin silicon nanowires for optical and electrical nitrogen dioxide detection

The ever-stronger attention paid to enhancing safety in the workplace has led to novel sensor development and improvement. Despite the technological progress, nanostructured sensors are not being commercially transferred due to expensive and non-microelectronic compatible materials and processing approaches. In this paper, the realization of a cost-effective sensor based on ultrathin silicon nanowires (Si NWs) for the detection of nitrogen dioxide (NO2 ) is reported. A modification of the metal-assisted chemical etching method allows light-emitting silicon nanowires to be obtained through a fast, low-cost, and industrially compatible approach. NO2 is a well-known dangerous gas that, even with a small concentration of 3 ppm, represents a serious hazard for human health. We exploit the particular optical and electrical properties of these Si NWs to reveal low NO2 concentrations through their photoluminescence (PL) and resistance variations reaching 2 ppm of NO2 . Indeed, these Si NWs offer a fast response and reversibility with both electrical and optical transductions. Despite the macro contacts affecting the electrical transduction, the sensing performances are of high interest for further developments. These promising performances coupled with the scalable Si NW synthesis could unfold opportunities for smaller sized and better performing sensors reaching the market for environmental monitoring

Advanced content-based semantic scene analysis and information retrieval: the SCHEMA project

The aim of the SCHEMA Network of Excellence is to bring together a critical mass of universities, research centers, industrial partners and end users, in order to design a reference system for content-based semantic scene analysis, interpretation and understanding. Relevant research areas include: content-based multimedia analysis and automatic annotation of semantic multimedia content, combined textual and multimedia information retrieval, semantic -web, MPEG-7 and MPEG-21 standards, user interfaces and human factors. In this paper, recent advances in content-based analysis, indexing and retrieval of digital media within the SCHEMA Network are presented. These advances will be integrated in the SCHEMA module-based, expandable reference system

The challenge of perioperative pain management in opioid-tolerant patients

The increasing number of opioid users among chronic pain patients, and opioid abusers among the general population, makes perioperative pain management challenging for health care professionals. Anesthesiologists, surgeons, and nurses should be familiar with some pharmacological phenomena which are typical of opioid users and abusers, such as tolerance, physical dependence, hyperalgesia, and addiction. Inadequate pain management is very common in these patients, due to common prejudices and fears. The target of preoperative evaluation is to identify comorbidities and risk factors and recognize signs and symptoms of opioid abuse and opioid withdrawal. Clinicians are encouraged to plan perioperative pain medications and to refer these patients to psychiatrists and addiction specialists for their evaluation. The aim of this review was to give practical suggestions for perioperative management of surgical opioid-tolerant patients, together with schemes of opioid conversion for chronic pain patients assuming oral or transdermal opioids, and patients under maintenance programs with methadone, buprenorphine, or naltrexone

Nouvelle découverte d'empreintes laissées par des dinosaures dans la formation des couches rouges (bassin de Cuzco-Sicuani, Sud du Pérou) : conséquences stratigraphiques et tectoniques

La découverte d'empreintes laissées par le dinosaures vers le sommet de la formation des Couches Rouges permet de préciser la stratigraphie du Sud du Pérou. La durée de la sédimentation continentale du bassin de Cuzco-Sicuani n'excéderait pas 20 Ma (santonien - paléocène) et non plus 45 Ma, comme cela était jusqu'à présent admis. Le bassin d'avant-pays de Cuzco-Sicuani est caractérisé par une déformation synsédimentaire essentiellement compressive pendant toute la durée de la sédimentation des "Couches Rouges". En conséquence, une durée équivalente à celle de cette sédimentation peut être retenue pour ces événements tectoniques qui marquent ici le début de la surrection de la chaîne andine. La phase péruvienne, traditionnellement placée vers 85 Ma, représenterait ainsi le début de ces événements tectoniques. (Résumé d'auteur

SPATION: Services Platforms and Applications for Transparent Information management in an in-hOme Network

The characteristics of PCs, huge storage capacity, tremendous processing power, and high flexibility are becoming available for consumer devices like set-top boxes, TVs, and VCRs. Interconnection of these devices and wireless communication with various portable devices will create a complex home system with the capacity to store many types of data and offer new ways of interacting with it. To offer the user high flexibility and ease of use, new solutions are required. Advanced retrieval methods are needed to support accessing data stored anywhere in the home system from any device. Meta-data obtained through analysis, services, and logging user behaviour is needed to support these functions. Transfer of data must be easy, and transfer and adaptation of accompanying meta-data must be transparent to the user. The combination of broadcast, storage, and internet will open the way to new types of applications and interactions with the home system. A large distributed storage space will be available in future home networks consisting of CE equipment, PCs and handheld devices. The objective of the project is to find innovative solutions for the movement, organization and retrieval of information in such a heterogeneous home system. Three major technical issues are under consideration: 1) New Meta-data computing methods are needed to support advanced retrieval methods. This means ways to solve how to generate meta-data by analysing the content, howto combine meta-data from various sources and how to transform meta-data for use by different devices; 2) New services providing meta-data, applications and UIs to make retrieval of information easier for non-IT-expert users; 3) Standards for inter-storage communication need to be extended in the area of handheld devices, meta-data storage and services

Performance of the PADME calorimeter prototype at the DAΦ\PhiNE BTF

The PADME experiment at the DA$\Phi$NE Beam-Test Facility (BTF) aims at searching for invisible decays of the dark photon by measuring the final state missing mass in the process $e^+e^- \to \gamma+ A'$, with $A'$ undetected. The measurement requires the determination of the 4-momentum of the recoil photon, performed using a homogeneous, highly segmented BGO crystals calorimeter. We report the results of the test of a 5$\times$5 crystals prototype performed with an electron beam at the BTF in July 2016