New insights into second and fourth-order direction finding for NonCircular sources

International audienceThese last three decades, many second order (SO) and higher order (HO) high resolution (HR) direction finding (DF) methods, such as 2q-MUSIC (q ≥ 1), exploiting the information contained in the SO or HO circular (C) cumulants of the data, have been developed. However, for 2qth-order non-circular (NC) sources such as M-PSK sources with M ≤ 2q, strong gains in performance may be obtained by taking into account the information contained in both 2qth-order C and NC cumulants of the data, giving rise to NC 2qth-order DF methods. Numerous NC DF methods have been developed these last fifteen years but mainly at the SO and under restrictive assumptions on the sources. The purpose of this paper is to give new insights into NC 2q-MUSIC methods for 1 ≤ q ≤ 2 and for arbitrary NC sources

La post-évaluation des investissements, un dispositif d'apprentissage et de gouvernance.

apprentissage; gouvernance; post-évaluation; investissement;

ICAR, a tool for Blind Source Separation using Fourth Order Statistics only

International audienceThe problem of blind separation of overdetermined mixtures of sources, that is, with fewer sources than (or as many sources as) sensors, is addressed in this paper. A new method, named ICAR (Independent Component Analysis using Redundancies in the quadricovariance), is proposed in order to process complex data. This method, without any whitening operation, only exploits some redundancies of a particular quadricovariance matrix of the data. Computer simulations demonstrate that ICAR offers in general good results and even outperforms classical methods in several situations: ICAR ~(i) succeeds in separating sources with low signal to noise ratios, ~(ii) does not require sources with different SO or/and FO spectral densities, ~(iii) is asymptotically not affected by the presence of a Gaussian noise with unknown spatial correlation, (iv) is not sensitive to an over estimation of the number of sources

Analyse du processus interactionnel entre les soignants et les personnes souffrant de démence qui présentent des comportements verbalement agressifs lors des soins d'hygiène du matin

La présente étude examine l’interaction entre les soignants et les personnes souffrant de démence qui résident en CHSLD au moment des soins du matin. L’objectif consiste à vérifier si certains comportements physiques et verbaux des soignants provoquent l’émission de CVA par le bénéficiaire. Neuf participants et leurs soignant sont été observés pendant les soins d’hygiène du matin. Les analyses séquentielles montrent que les énoncés négatifs, les consignes, les touchers liés au soin et les comportements physiques non liés au soin sont plus susceptibles de provoquer les CVA, comparativement aux énoncés positifs et aux comportements verbaux non liés au soin. Les soignants répondent aux CVA par des énoncés négatifs. Ces résultats permettront de contribuer à l’élaboration de méthodes d’intervention efficaces dans le traitement des CVA

Limites des estimateurs classiques de cumulants d'ordre quatre pour la separation aveugle de sources cyclostationnaires

La plupart des méthodes de séparation aveugle de sources aux ordres supérieurs apparues ces dix dernières années ont été développées dans le but de permettre la séparation aveugle de sources statistiquement indépendantes, supposées stationnaires et ergodiques. Toutefois, dans de nombreuses situations d'intérêt pratique (radiocommunications numériques) les sources traitées ne sont pas stationnaires mais (quasi)-cyclostationnaires et l'on peut dès lors se demander si les performances des séparateurs aveugles précédents se trouvent affectées par la non stationnarité potentielle des sources. L'objet de ce papier est d'apporter un certain nombre de réponses à cette question à travers l'analyse du comportement des estimateurs classiques de cumulant d'ordre 4 en présence de sources (quasi) -cyclostationnaires

Introduction

Ce numéro de Géographie et cultures se propose d’explorer les dimensions spatiales des mémoires, envisagées à la fois comme un ensemble de modalités et un agence­ment de convocations du passé dans le présent. Ces trente dernières années ont été riches en recherches sur la question des mémoires (Klein, 2000 ; Radstone, 2000 ; Zelizer, 1995 ; Nicolas, 2014), de leurs usages et mésusages (Lavabre, 2000), en histoire bien évidemment (Nora, 1984-1992 ; Assmann, 1995 ; Offenstadt, 1999), mais aussi..

Serological evidence for Japanese encephalitis and West Nile virus infections in domestic birds in Cambodia

Mosquito-borne flaviviruses with an enzootic transmission cycle like Japanese encephalitis virus (JEV) and West Nile virus (WNV) are a major public health concern. The circulation of JEV in Southeast Asia is well-documented, and the important role of pigs as amplification hosts for the virus is long known. The influence of other domestic animals especially poultry that lives in high abundance and close proximity to humans is not intensively analyzed. Another understudied field in Asia is the presence of the closely related WNV. Such analyses are difficult to perform due to the intense antigenic cross-reactivity between these viruses and the lack of suitable standardized serological assays. The main objective of this study was to assess the prevalence of JEV and WNV flaviviruses in domestic birds, detailed in chickens and ducks, in three different Cambodian provinces. We determined the flavivirus seroprevalence using an hemagglutination inhibition assay (HIA). Additionally, we investigated in positive samples the presence of JEV and WNV neutralizing antibodies (nAb) using foci reduction neutralization test (FRNT). We found 29% (180/620) of the investigated birds positive for flavivirus antibodies with an age-depended increase of the seroprevalence (OR = 1.04) and a higher prevalence in ducks compared to chicken (OR = 3.01). Within the flavivirus-positive birds, we found 43% (28/65) with nAb against JEV. We also observed the expected cross-reactivity between JEV and WNV, by identifying 18.5% double-positive birds that had higher titers of nAb than single-positive birds. Additionally, seven domestic birds (10.7%) showed only nAb against WNV and no nAb against JEV. Our study provides evidence for an intense JEV circulation in domestic birds in Cambodia, and the first serological evidence for WNV presence in Southeast Asia since decades. These findings mark the need for a re-definition of areas at risk for JEV and WNV transmission, and the need for further and intensified surveillance of mosquito-transmitted diseases in domestic animals

Asymmetrical stripline based method for retrieving the electromagnetic properties of metamaterials

International audienceAn experimental characterization technique for determining the electromagnetic properties of metamaterials in the microwave frequency band is presented. The method consists in measuring the S-parameters of an asymmetrical stripline partially filled with the sample to be characterized. For retrieving the characteristic parameters, two different approaches based on quasi-static approximations are compared. This measurement cell allows an "in situ" characterization because it reproduces the electromagnetic environment frequently found in planar technologies for microwave applications of metamaterials. The whole sample is uniformly excited in magnitude and direction by the interacting electromagnetic field which guarantees representativeness of extracted permittivity and permeability and avoids possible inconsistencies due to anisotropy and heterogeneity of metamaterials