Faint dwarf galaxies in the Next Generation Virgo cluster Survey

The Next Generation Virgo Cluster Survey (NGVS) is a CFHT Large Program that is using the wide field of view capabilities of the MegaCam camera to map the entire Virgo Cluster from its core to virial radius. The observing strategy has been optimized to detect very low surface brightness structures in the cluster, including intracluster stellar streams and faint dwarf spheroidal galaxies. We present here the current status of this ongoing survey, with an emphasis on the detection and analysis of the very low-mass galaxies in the cluster that have been revealed by the NGVS.Comment: 6 pages, 2 figures, Conference Proceedings: "A Universe of Dwarf Galaxies", 14-18 June 2010, Lyon, Franc

Spectral analysis of surface waves for the characterization of the EDZ in circular galleries

Lors du creusement de galeries profondes ou de tunnels, les propriétés hydromécaniques de la roche encaissante autour de l'ouvrage sont altérées sur une certaine distance qui dépend de la nature de la roche et du type d'excavation. Une telle zone est appelée Excavation Damaged Zone (EDZ). Cette altération de l'encaissant se caractérise par une densification de la fracturation intrinsèque de la roche. La connaissance des caractéristiques mécaniques de l'EDZ ainsi que son extension est actuellement un axe majeur de recherche notamment pour la conception de centres de stockage souterrains des déchets nucléaires. En effet, l'EDZ, par son réseau de fractures, est considéré comme un chemin potentiel pour les radionucléides et donc comme un facteur de possible contamination du milieu. Les méthodes géophysiques initialement utilisées à des échelles kilométriques pour analyser les événements géologiques, sont dorénavant transposées à des échelles métriques voire centimétriques et appliquées en génie civil ou dans tout autre domaine de l'ingénierie. L'intérêt de telles méthodes est leur caractère non destructif qui les rend faciles d'utilisation et généralement moins coûteuses que d'autres méthodes destructives. Elles permettent aussi un suivi dans le temps de l'évolution des propriétés des matériaux auscultés. La MASW (Multiple Acquisition of Surface Wave) est une méthode géophysique utilisant le principe de dispersion des ondes de surface (Park et al, 1999). Cette méthode a été transposée dans ce contexte afin d'obtenir un profil 1D des vitesses des ondes de cisaillement (S) autour d'un ouvrage souterrain et ainsi de déterminer l'extension et les caractéristiques en terme de vitesse des ondes S de l'EDZ. L'intérêt de cette méthode est sa facilité de mise en oeuvre et la possibilité de l'utiliser sans restriction majeure

Determination of the standard deviation for proficiency assessment from past participant’s performances

The “uncertainty function” introduced by Thompson et al. estimates the reproducibility standard deviation (SR) as a function of concentration. This model was successfully applied to a data set derived from three proficiency testing schemes aiming at the quantification of three toxic elements (cadmium, lead and mercury) in blood and urine. A threshold concentration was determined for each element. Below this concentration SR is found to be constant, while above it the reproducibility relative standard deviation is constant. This model allows the a priori estimation of standard deviation for performance assessment for proficiency testing rounds.JRC.D.5-Standards for Food Bioscienc

The Next Generation Virgo Cluster Survey. IX. Estimating the Efficiency of Galaxy Formation on the Lowest-Mass Scales

The Next Generation Virgo Cluster Survey has recently determined the luminosity function of galaxies in the core of the Virgo cluster down to unprecedented magnitude and surface brightness limits. Comparing simulations of cluster formation to the derived central stellar mass function, we attempt to estimate the stellar-to-halo-mass ratio (SHMR) for dwarf galaxies, as it would have been before they fell into the cluster. This approach ignores several details and complications, e.g., the contribution of ongoing star formation to the present-day stellar mass of cluster members, and the effects of adiabatic contraction and/or violent feedback on the subhalo and cluster potentials. The final results are startlingly simple, however; we find that the trends in the SHMR determined previously for bright galaxies appear to extend down in a scale-invariant way to the faintest objects detected in the survey. These results extend measurements of the formation efficiency of field galaxies by two decades in halo mass, or five decades in stellar mass, down to some of the least massive dwarf galaxies known, with stellar masses of $\sim 10^5 M_\odot$.Comment: 18 pages, 12 figures; published in ApJ July 1st 201

Determination of the standard deviation for proficiency assessment from past participant's performances

The "uncertainty function" introduced by Thompson et al. estimates the reproducibility standard deviation as a function of concentration or mass fraction. This model was successfully applied to data derived from three proficiency testing schemes aiming at the quantification of cadmium, lead and mercury in blood and urine. This model allows the estimation of standard deviation for the performance assessment for proficiency testing rounds

Can Functional Capacity Tests Predict Future Work Capacity in Patients With Whiplash-Associated Disorders?

AbstractObjectiveTo determine whether functional capacity evaluation (FCE) tests predict future work capacity (WC) of patients with whiplash-associated disorders (WADs) grades I and II who did not regain full WC 6 to 12 weeks after injury.DesignProspective cohort study.SettingRehabilitation center.ParticipantsWorkers (N=267) listed on workers' compensation with grade I or II WADs 6 to 12 weeks after injury.InterventionsPatients performed 8 work-related FCE tests.Main Outcome MeasuresWC (0–100%) measured at baseline and 1, 3, 6, and 12 months after testing. Correlation coefficients between FCE tests and WC were calculated. A linear mixed-model analysis was used to assess the association between FCE and future WC.ResultsMean ± SD WC increased over time from 20.8%±27.6% at baseline to 32.3%±38.4%, 51.3%±42.8%, 65.6%±42.2%, and 83.2%±35.0% at the 1-, 3-, 6-, and 12-month follow-ups, respectively. Correlation coefficients between FCE tests and WC ranged from r=.06 (lifting low at 12-mo follow-up) to r=.39 (walking speed at 3mo). Strength of the correlations decreased over time. FCE tests did not predict WC at follow-up. The predictors of WC were ln (time) (β=23.74), mother language (β=5.49), WC at baseline (β=1.01), and self-reported disability (β=−.20). Two interaction terms, ln (time) × WC (β=−.19) and ln (time) × self-reported disability (β=−.21), were significant predictors of WC.ConclusionsFCE tests performed within 6 to 12 weeks after WADs injury grades I and II are associated with WC at baseline but do not predict future WC, whereas time course, mother language, WC at baseline, and self-reported disability do predict future WC. Additionally, the interaction between time course WC at baseline and self-reported disability predicted future WC

Sequence and structure of the mouse gene coding for the largest neurofilament subunit.

We have determined the complete nucleotide sequence of the mouse gene encoding the neurofilament NF-H protein. The C-terminal domain of NF-H is very rich in charged amino acids (aa) and contains a 3-aa sequence, Lys-Ser-Pro, that is repeated 51 times within a stretch of 368 aa. The location of this serine-rich repeat in the phosphorylated domain of NF-H indicates that it represents the major protein kinase recognition site. The nfh gene shares two common intron positions with the nfl and nfm genes, but has an additional intron that occurs at a location equivalent to one of the introns in non-neuronal intermediate filament-coding genes. This additional nfh intron may have been acquired via duplication of a primordial intermediate filament gene