Time filter

Source Type

Châtenay-Malabry, France

Roche D.B.,Institute Of Genomique | Roche D.B.,French National Center for Scientific Research | Roche D.B.,University of Evry Val dEssonne | Roche D.B.,UniverSud Paris | And 3 more authors.
Protein Science | Year: 2015

As the largest fraction of any proteome does not carry out enzymatic functions, and in order to leverage 3D structural data for the annotation of increasingly higher volumes of sequence data, we wanted to assess the strength of the link between coarse grained structural data (i.e., homologous superfamily level) and the enzymatic versus non-enzymatic nature of protein sequences. To probe this relationship, we took advantage of 41 phylogenetically diverse (encompassing 11 distinct phyla) genomes recently sequenced within the GEBA initiative, for which we integrated structural information, as defined by CATH, with enzyme level information, as defined by Enzyme Commission (EC) numbers. This analysis revealed that only a very small fraction (about 1%) of domain sequences occurring in the analyzed genomes was found to be associated with homologous superfamilies strongly indicative of enzymatic function. Resorting to less stringent criteria to define enzyme versus non-enzyme biased structural classes or excluding highly prevalent folds from the analysis had only modest effect on this proportion. Thus, the low genomic coverage by structurally anchored protein domains strongly associated to catalytic activities indicates that, on its own, the power of coarse grained structural information to infer the general property of being an enzyme is rather limited. © 2015 The Protein Society. Source

Busic A.,French Institute for Research in Computer Science and Automation | Fourneau J.M.,UniverSud Paris
Proceedings - 7th International Conference on the Quantitative Evaluation of Systems, QEST 2010 | Year: 2010

We present new algorithms we have recently introduced and which provide iterative component-wise bounds of the steady-state distribution of Markov chains. At each iteration we improve the quality of the bounds and these bounds are tight as the limit is the exact solution. As the algorithms are based on the product matrix-vector and properties of (max,+) sequences, they can easily be included into numerical packages. We present some examples and how we have implemented these algorithms in the Xborne tool. © 2010 IEEE. Source

Adelaide L.,University Paris Est Creteil | Richard B.,University Paris Est Creteil | Richard B.,UniverSud Paris | Ragueneau F.,UniverSud Paris | Cremona C.,Direction de la Recherche et de lInnovation
European Journal of Environmental and Civil Engineering | Year: 2012

One of major causes responsible for the performance loss of reinforced concrete structures is the corrosion phenomenon. Thereby, taking into account the local effects of the steel/concrete interface is of primary importance to predict properly the response of corroded reinforced concrete structures. A multifiber-based model including the steel/concrete interface is proposed. This interface model allows taking into consideration the bond strength variation due to corrosion. Such an approach leads to reasonable computational costs which a powerful feature of the model. A numerical study of beams already studied in the French project « benchmark des poutres de la Rance» is proposed in order to show the efficiency and reliability of the proposed model. © 2012 Taylor & Francis. Source

Dionisi D.,UniverSud Paris | Dionisi D.,CNR Institute of atmospheric Sciences and Climate | Keckhut P.,UniverSud Paris | Liberti G.L.,CNR Institute of atmospheric Sciences and Climate | And 2 more authors.
Atmospheric Chemistry and Physics | Year: 2013

A methodology to identify and characterize cirrus clouds has been developed and applied to the multichannel-multiwavelength Rayleigh-Mie-Raman (RMR) lidar in Rome Tor Vergata (RTV). A set of 167 cirrus cases, defined on the basis of quasi-stationary temporal period conditions, has been selected in a data set consisting of about 500 h of nighttime lidar sessions acquired between February 2007 and April 2010. The derived lidar parameters (effective height, geometrical and optical thickness and mean back-scattering ratio) and the cirrus mid-height temperature (estimated from the radiosonde data of Pratica di Mare, WMO, World Meteorological Organization, site no. 16245) of this sample have been analyzed by the means of a clustering multivariate analysis. This approach identified four cirrus classes above the RTV site: two thin cirrus clusters in mid- and upper troposphere and two thick cirrus clusters in mid-upper troposphere. These results, which are very similar to those derived through the same approach at the lidar site of the Observatoire de Haute-Provence (OHP), allows characterization of cirrus clouds over the RTV site and attests to the robustness of such classification.

To acquire some indications about the cirrus generation methods for the different classes, analyses of the extinction-to-backscatter ratio (lidar ratio, LReff, in terms of frequency distribution functions and dependencies on the mid-height cirrus temperature, have been performed. A preliminary study relating some meteorological parameters (e.g., relative humidity, wind components) to cirrus clusters has also been conducted.

The RTV cirrus results, recomputed through the cirrus classification by Sassen and Cho (1992), show good agreement with other midlatitude lidar cirrus observations for the relative occurrence of subvisible (SVC), thin and opaque cirrus classes (10%, 49% and 41%, respectively). The overall mean value of cirrus optical depth is 0.37 ± 0.18, while most retrieved LReff values range between 10-60 sr, and the estimated mean value is 31 ± 15 sr, similar to LR values of lower latitude cirrus measurements.

The obtained results are consistent with previous studies conducted with different systems and confirm that cirrus classification based on a statistical approach seems to be a good tool both to validate the height-resolved cirrus fields calculated by models and to investigate the key processes governing cirrus formation and evolution. However, the lidar ratio and optical depth analyses are affected by some uncertainties (e.g., lidar error noise, multiple scattering effects, supercooled water clouds) that reduce the confidence of the results. Future studies are needed to improve the characterization of the cirrus optical properties and, thus, the determination of their radiative impact. © 2013 Author(s).f 0. Source

Peralta C.,Institute dInvestigacions Biomediques August Pi i Sunyer | Peralta C.,Research Center Biomedica En Red Of Enfermedades Hepaticas gestivas | Brenner C.,University Paris - Sud | Brenner C.,UniverSud Paris
Current Medicinal Chemistry | Year: 2011

In many physiopathological conditions, the cell controls its proper dysfunction via activation of the unfolded protein response to restore efficient protein synthesis and folding in the endoplasmic reticulum. However, whether the aim of unfolded protein response is to promote the cell survival, it can also lead to induction of cell death and then affect the cell fate. Recently, endoplasmic reticulum stress appeared to be critical for acute as well as chronic diseases including neurodegeneration, cardiac disease, cancer, obesity, type 2 diabetes, and ischemia/reperfusion injury. Therefore, inhibition of the endoplasmic reticulum stress could constitute a promising therapeutic strategy to limit cellular damage in pathologies such as hepatic ischemia/reperfusion. © 2011 Bentham Science Publishers Ltd. Source

Discover hidden collaborations