Photometric redshifts: estimating their contamination and distribution using clustering information

We present a new technique to estimate the level of contamination between photometric redshift bins. If the true angular cross-correlation between redshift bins can be safely assumed to be zero, any measured cross-correlation is a result of contamination between the bins. We present the theory for an arbitrary number of redshift bins, and discuss in detail the case of two and three bins which can be easily solved analytically. We use mock catalogues constructed from the Millennium Simulation to test the method, showing that artificial contamination can be successfully recovered with our method. We find that degeneracies in the parameter space prohibit us from determining a unique solution for the contamination, though constraints are made which can be improved with larger data sets. We then apply the method to an observational galaxy survey: the deep component of the Canada-France-Hawaii Telescope Legacy Survey. We estimate the level of contamination between photometric redshift bins and demonstrate our ability to reconstruct both the true redshift distribution and the true average redshift of galaxies in each photometric bin.Comment: 14 pages, 12 figures, accepted for publication in MNRAS V2: Section 4.4 added. Significant additions to analysis in section 5.

Cosmological Weak Lensing

We present the current status of cosmic shear studies and their implications on cosmological models. Theoretical expectations and observational results are discussed in the framework of standard cosmology and CDM scenarios. The potentials of the next generation cosmic shear surveys are discussed.Comment: Latex, 10 pages. To appear in ``Astronomy, Cosmology and Fundamental Physics'', ESO-CERN-ESA Symposium. P. A. Shaver, L. Di Lella, and A. Gimenez Ed

[A little less respite for hepatocellular carcinoma?]

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Pontin and reptin, two related ATPases with multiple roles in cancer.: Pontin and Reptin in cancer

International audienceStudies in model organisms or cultured human cells suggest potential implications in carcinogenesis for the AAA+ ATPases Pontin and Reptin. Both proteins are associated with several chromatin-remodeling complexes and have many functions including transcriptional regulation, DNA damage repair, and telomerase activity. They also interact with major oncogenic actors such as beta-catenin and c-myc and regulate their oncogenic function. We only now begin to get insight into the role of Pontin and Reptin in human cancers. [Cancer Res 2008;68(17):6873-6]

Analyse biomécanique du complexe lombo-pelvi-fémoral complex during the one-sided tilt test ::a pilot study in triathletes

Introduction: The evaluation of the risk of low back pain remains complex as it lacks evidence-based recommendations and a reliable functional test. The one-sided tilt test can provide additional information on the dynamics of the lumbo- pelvic complex. However, little is known about the expected movement. This study aims to identify different patterns of movement during the test in a healthy population of triathletes and provide preliminary normative values. Method: Twenty-tvvo asymptomatic triathletes were instructed to perform the right and left one-sided tilt test. Three-dimensional kinematics were obtained from a 24-camera motion analysis system. This made it possible to mode! the range of motions of the torso, the pelvis, the hips and the kneesusing OpenSim. Latent class analysis was then used to identify different classes of movement combination. Results: Four classes of possible movement combinations w ere identified. Knee flexion was most limited with reduced range of pelvis tilt motion, then rotation, and fina lly list. These patterns were different between the left and right side in 31.8% of the studied population. Discussion: This approach enabled the ident ification of athletes with limited range of motion on the lumbar-pelvic-femoral complex. Conclusions : Polyarticular functional movement could help understand different strategies and kinematic adaptations linked to over- or under- mechanical load of specific joints.Introduction: L’évaluation du risque de lombalgie demeure complexe, car elle manque de recommandations fondées sur des données probantes et de tests fonctionnels fiables. Le test d’inclinaison unilatérale du bassin propose une analyse dynamique du complexe lombo-pelvi-fémoral. Il n’existe cependant pas de description quantitative du mouvement attendu chez une population asymptomatique de triathlètes. Cette étude vise à identifier et à différencier des schémas de mouvement du complexe lombo-pelvi-fémoral lors du test et d’en fournir des premières valeurs normatives. Méthode: Vingt-deux triathlètes asymptomatiques ont reçu l’instruction d’effectuer le test d’inclinaison latérale du bassin de manière bilatérale. La cinématique 3D a été obtenue à partir d’un système d’analyse de mouvement à 24 caméras. Ceci a permis de modéliser via OpenSim l’amplitude articulaire du mouvement effectué par le tronc, le bassin, les hanches et les genoux. Une analyse de classe par latence a permis d’identifier les «classes» de mouvements possibles. Résultats : Quatre classes de mouvements possibles ont été identifiées. La mobilisation du genou était limitée au maximum en présence d’une limitation de l’inclinaison du bassin, puis de la rotation du bassin, et finalement de l’antéversion du bassin. Ces schémas étaient présents de manière différenciée entre le côté gauche et le côté droit chez 31.8% des participants. Discussion: Cette approche permet d’identifier des athlètes ayant des limitations de mobilité du complexe lombo-pelvifémoral. Conclusion: L’interprétation du mouvement fonctionnel polyarticulaire pourrait aider à identifier et comprendre différentes stratégies ou adaptations cinématiques expliquant la sur ou sous sollicitation de certaines articulations

Complex Conductivity of Graphitic Schists and Sandstones

International audienceSpectral induced polarization spectra were carried out on three graphitic schists and two graphitic sandstones. The microstructural arrangement of graphite of two graphitic schists was studied with thin sections using transmitted and reflected light optical and electron microscopic methods. Chemical maps of selected areas confirm the presence of carbon. The complex conductivity spectra were measured in the frequency range 10 mHz to 45 kHz and in the temperature range +20°C down to −15°C. The measured spectra are fitted with a double Cole-Cole complex conductivity model with one component associated with the polarization of graphite and the second component associated with the Maxwell-Wagner polarization. The Cole-Cole exponent and the chargeability are observed to be almost independent of temperature including in freezing conditions. The conductivity and relaxation time are dependent on the temperature in a predictable way. As long as the temperature decreases, the electrical conductivity decreases and the relaxation time increases. A finite element model is able to reproduce the observed results. In this model, we consider an intragrain polarization mechanism for the graphite and a change of the conductivity of the background material modeled with an exponential freezing curve. One of the core sample (a black schist), very rich in graphite, appears to be characterized by a very high conductivity (approximately 30 S/m). Two induced polarization profiles are discussed in the area of Thorens. The model is applied to the chargeability data to map the volumetric content of graphite

In vivo silencing of Reptin blocks the progression of human hepatocellular carcinoma in xenografts and is associated with replicative senescence.: Reptin silencing blocks liver cancer progression

International audienceBACKGROUND & AIMS: We previously showed that Reptin is overexpressed in hepatocellular carcinoma (HCC), and that in vitro depletion of Reptin with siRNAs led to HCC cell growth arrest and apoptosis. Here, we asked whether in vivo targeting of Reptin in established tumours had a therapeutic effect. METHODS: We used lentiviral vectors to construct HuH7 and Hep3B cell lines with doxycycline (Dox)-dependent expression of Reptin (R2) or control shRNA (GL2). Cells were injected subcutaneously into immunodeficient mice, and Dox was given when tumours reached a volume of 250 mm(3). RESULTS: In vitro, the growth of GL2-Dox, GL2+Dox, and R2-Dox cells was undistinguishable whereas that of R2+Dox cells stopped 4 days after Dox treatment. The growth decrease was associated with increased apoptosis, and evidence of replicative senescence, as shown by staining for acid beta-galactosidase and the presence of senescence-associated heterochromatin foci. In xenografted mice, R2+Dox tumour growth stagnated or even regressed with prolonged treatment in contrast with the GL2-Dox, GL2+Dox, and R2-Dox tumours that progressed steadily. The blockage of tumour progression was associated with the induction of senescence and reduced cell proliferation. CONCLUSIONS: In vivo Reptin depletion leads to tumour growth arrest. Reptin may prove a valuable target in HCC