A New Type of Compton Polarimeter for Jefferson Lab Hall A

In this paper, we present the principle and the studies for a new type of Compton polarimeter based on the use of power buildup Fabry-Perot cavity to get a 3% measurement of the Jefferson Lab electron polarization within minutes

Intrinsic General Relativity and Clifford algebra

International audienceThis paper proposes to go beyond the Einstein General Rel-ativity theory. The intrinsic writing of the General Relativity theory in a suitable framework allows us to naturally introduce Clifford algebra in a generalization that would enable a unification with the Dirac's theory. This is done starting by considering a submodule V of functions from an abelian group G to itself. In a second time, the group G is replaced by a unitary ring that permits to add new properties as the Leibniz rule for derivations. At last, in the particular case when V is a free G-submodule, it becomes possible to write everything with coordinates and the well-known writing of the classical General Relativity and the Dirac equation can appear

First record of Ptychoglossus brevifrontalis Boulenger, 1912 (Squamata, Alopoglossidae) in French Guiana

One specimen of Ptychoglossus brevifrontalis Boulenger, 1912 was found during a field survey in the core area of the Amazonian National Park of French Guiana in the southern part of the country. Despite intensive herpetological surveys in French Guiana during the last three decades, this is the first record of the species for this country. This new locality extends the distribution of the species and draws attention to the need for more study of litter-dwelling lizards in French Guiana

First record of Ptychoglossus brevifrontalis Boulenger, 1912 (Squamata, Alopoglossidae) in French Guiana

One specimen of Ptychoglossus brevifrontalis Boulenger, 1912 was found during a field survey in the core area of the Amazonian National Park of French Guiana in the southern part of the country. Despite intensive herpetological surveys in French Guiana during the last three decades, this is the first record of the species for this country. This new locality extends the distribution of the species and draws attention to the need for more study of litter-dwelling lizards in French Guiana

Ensemble Forecasting at RSMC La Réunion

International audienceCommunication about Ensemble Forecasting at RSMC La Réunio

Extraction de données et apprentissage automatique pour les sites web adaptatifs

Les travaux pr esent es se situent dans le cadre d extraction de connaissance a partir de donn ees. Un contexte d etude int eressant et d actualit e a et e choisi : les sites web adaptatifs. Pour mettre en oeuvre, de maniere la plus automatique possible, de tels sites adapt es aux utilisateurs, nous d ecidons d apprendre des modeles d utilisateurs ou, plus pr ecis ement, de leurs types de navigations sur un site web donn e. Ces modeles sont appris par inf erence grammaticale. Les donn ees disponibles li ees au contexte du Web sont particulierement difficiles a r ecup erer proprement. Nous choisissons de nous focaliser sur les fichiers de logs serveur en supprimant le bruit inh erent a ces derniers. L inf erence grammaticale peut g en eraliser ses donn ees d entr ee pour obtenir de bons modeles de langages. Nous travaillons sur les mesures de similarit e entre langages pour l evaluation de la qualit e des modeles appris. L introduction d une mesure euclidienne entre modeles de langages repr esent es sous forme d automates permet de pallier les problemes des m etriques existantes. Des r esultats th eoriques montrent que cette mesure a les propri et es d une vraie distance. Enfin, nous pr esentons divers r esultats d exp erimentation sur des donn ees du web que nous pr e-traitons avant d apprendre gr ace a elles des modeles utilisateurs issus de l inf erence grammaticale stochastique. Les r esultats obtenus sont sensiblement meilleurs que ceux pr esents dans l etat de l art, notamment sur les t aches de pr ediction de nouvelle page dans une navigation utilisateur.Our work is about Knowledge Discovery and Data Mining. We focus on web data including server log files. In order to know automatically how to adapt a web site, we decide to learn grammatical models about users behaviors. We show in this work how the web data are difficult to acquire in order to use them in a grammatical inference process. We try to eliminate the almost totality of the noise which is present in these data. We also show how grammatical inference can learn good models by generalizing enough its input data. We explain how difficult the evaluation of the quality of learned models is, and we introduce an euclidean measure between languages models represented by automata. We prove that this measure is a true distance in a mathematical sense. Finally, we propose our experimentation results: we show that our method (from the prepossessing of the data to the evaluation of learned models) gives better success rates for the new page prediction task which is very common in web usage mining.ST ETIENNE-ENS des Mines (422182304) / SudocSudocFranceF

First record of Ptychoglossus brevifrontalis Boulenger, 1912 (Squamata, Alopoglossidae) in French Guiana

One specimen of Ptychoglossus brevifrontalis Boulenger, 1912 was found during a field survey in the core area of the Amazonian National Park of French Guiana in the southern part of the country. Despite intensive herpetological surveys in French Guiana during the last three decades, this is the first record of the species for this country. This new locality extends the distribution of the species and draws attention to the need for more study of litter-dwelling lizards in French Guiana

Compact Isoflux X-band Payload Telemetry Antenna with Simultaneous Dual Circular Polarization for LEO Satellite Applications

International audienceThis paper describes a compact isoflux X-band payload telemetry and data handling antenna with simultaneous dual circular polarization for Low Earth Orbits (LEO) satellite applications. The main objective of this antenna is to use polarization diversity to improve the efficiency of the payload telemetry link. Some solutions have already been proposed to that end, but the studied antenna combines both good electromagnetic performances and compactness. This high power capability waveguide antenna presents an axial ratio (AR) lower than 2.5 dB over the 8.025-8.4 GHz frequency band at the limit of coverage, i.e. 65°, for any azimuth angle (φ). It has been designed, realized and successfully measured