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Search Results: 1 - 10 of 201068 matches for " P. Perrin "
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Characteristics of Prostate Cancers Missed by Biopsies: Evaluation of Cumulative Tumor Volume Missed According to Cancer True Prevalence  [PDF]
Nicolas B. Delongchamps, Gustavo de la Roza, Paul Perrin, Micha?l Peyromaure, Gabriel P. Haas
Open Journal of Urology (OJU) , 2013, DOI: 10.4236/oju.2013.35039
Abstract:

Purpose: To characterize missed prostate tumors and their cumulative volume with various biopsy regimens to determine optimal biopsy schemes. Methods: We performed 6, 12 and 18-core needle biopsies on 165 and 36-core biopsies on 47 autopsy prostates, respectively. The 6-core biopsy included 6 cores from the mid peripheral zone (MPZ), the 12-core biopsy included 6 cores from the MPZ and lateral PZ (LPZ), and the 18-core biopsies included 6 cores from the MPZ, LPZ and central zone (CZ). The 36-core biopsies included 12 cores in each of these 3 areas. We analyzed the sensitivity of biopsies at each site and evaluated the cumulative volume of cancers and tumor foci missed. Results: Whole-mount analysis identified 59 cancers, 110 tumor foci, and a total cumulative tumor volume of 43 cm3. The percentage of tumor foci and corresponding cumulative volume missed with 6, 12, 18 and 36-core biopsies were of 79% and 58%, 64% and 48%, 57% and 26%, and 42% and 17%, respectively (p < 0.05). 12-core biopsies from the MPZ and LPZ performed best for clinically significant cancers detection. However, increasing the number of cores over the 6-core biopsy cutoff increased solely the detection of tumor foci < 0.5 cm3. Conclusion:

Functional Methods and Effective Potentials for Nonlinear Composites
Y. -P. Pellegrini,M. Barthelemy,G. Perrin
Physics , 1999, DOI: 10.1016/S0022-5096(99)00040-X
Abstract: A formulation of variational principles in terms of functional integrals is proposed for any type of local plastic potentials. The minimization problem is reduced to the computation of a path integral. This integral can be used as a starting point for different approximations. As a first application, it is shown how to compute to second-order the weak-disorder perturbative expansion of the effective potentials in random composite. The three-dimensional results of Suquet and Ponte-Casta\~neda (1993) for the plastic dissipation potential with uniform applied tractions are retrieved and extended to any space dimension, taking correlations into account. In addition, the viscoplastic potential is also computed for uniform strain rates.
Synthetic review on the different anthropological aspects of hemoglobinopathies in Tunisia
AH Khelil, P Perrin, G Lefranc, JB Chibani
International Journal of Modern Anthropology , 2012,
Abstract: Hemoglobinopathies are a group of hereditary hemolytic anemia characterized by qualitative (sickle cell disease) or quantitative (thalassemia) defects in the alpha or beta-globin chain synthesis. Homozygotes or compound heterozygotes for the mutated alpha or beta-globin genes can cause severe anemia at an early age. These pathologies are common in some areas (Mediterranean, Africa, India, and Southeast Asia). Tunisia, by its geographical location, its history and its socio-economic system, is particularly concerned by these pathologies. The frequency and severity of the beta-thalassemia syndrome justify the establishment of prevention programs including screening and genetic counseling especially in regions with relatively high degree of consanguinity. Molecular investigations are conducted to identify the molecular defects involved in β-thalassemia. Determination of the spectrum and distribution of beta globin gene mutations and haplotypes associated gave us the opportunity to develop and improve diagnostic tests and eventually to offer ante-natal diagnosis. In addition, molecular analyses gave us important anthropological information about the origins and the spread of Hemoglobinopathies mutations. Investigations have been conducted to propose the origin and the migration schemes of the most frequent β-thalassemia mutations in Tunisia (codon 39 and IVSI 110): a west-Mediterranean and ancient origin for codon 39 and an east-Mediterranean origin (Anatolia) for IVSI 110 during the Neolithic period. Concerning the βS mutation of the sickle cell anemia, the β-globin cluster restriction enzyme haplotypes and the sequence polymorphism analyses show a multicentric origin for this mutation. Arose about 3,000 years ago, this mutation was very likely introduced in North Africa from sub-Saharan Africa.
How crucial is it to account for the antecedent moisture conditions in flood forecasting? Comparison of event-based and continuous approaches on 178 catchments
L. Berthet, V. Andréassian, C. Perrin,P. Javelle
Hydrology and Earth System Sciences (HESS) & Discussions (HESSD) , 2009,
Abstract: This paper compares event-based and continuous hydrological modelling approaches for real-time forecasting of river flows. Both approaches are compared using a lumped hydrologic model (whose structure includes a soil moisture accounting (SMA) store and a routing store) on a data set of 178 French catchments. The main focus of this study was to investigate the actual impact of soil moisture initial conditions on the performance of flood forecasting models and the possible compensations with updating techniques. The rainfall-runoff model assimilation technique we used does not impact the SMA component of the model but only its routing part. Tests were made by running the SMA store continuously or on event basis, everything else being equal. The results show that the continuous approach remains the reference to ensure good forecasting performances. We show, however, that the possibility to assimilate the last observed flow considerably reduces the differences in performance. Last, we present a robust alternative to initialize the SMA store where continuous approaches are impossible because of data availability problems.
How crucial is it to account for the Antecedent Moisture Conditions in flood forecasting? Comparison of event-based and continuous approaches on 178 catchments
L. Berthet,V. Andréassian,C. Perrin,P. Javelle
Hydrology and Earth System Sciences Discussions , 2009,
Abstract: This paper compares event-based and continuous hydrological modelling approaches for real-time forecasting of river flows. Both approaches are compared using a lumped hydrologic model (whose structure includes a soil moisture accounting (SMA) store and a routing store) on a data set of 178 French catchments. The main focus of this study was to investigate the actual impact of soil moisture initial conditions on the performance of flood forecasting models and the possible compensations with updating techniques. The rainfall runoff model assimilation technique we used does not impact the SMA component of the model but only its routing part. Tests were made by running the SMA store continuously or on event basis, everything else being equal. The results show that the continuous approach remains the reference to ensure good forecasting performances. We show, however, that the possibility to assimilate the last observed flow considerably reduces the differences in performance. Last, we present a robust alternative to initialize the SMA store where continuous approaches are impossible because of data availability problems.
A test of five mechanisms of species coexistence between rodents in a southern African savanna
M.R. Perrin,B.P. Kotler
African Zoology , 2011,
Abstract: The operation of five different mechanisms of species coexistence in a community of rodents was examined in a semi-arid Kalahari savanna in southern Africa. The two most common species were Tatera leucogaster (bushveld gerbil) and Rhabdomys pumilio (striped mouse). The mechanisms examined were habitat selection in a mosaic, microhabitat selection, spatial variation in resource abundance, temporal variation in resource abundance, and diet partitioning. The rodents were censused using mark–recapture live trapping, activity measured using sand-tracking, and foraging efficiency measured using giving-up densities (GUDs; the amount of food remaining following patch exploitation) in experimental food patches. There was no support for any of the five mechanisms: T. leucogaster tended to be a more efficient and mobile forager than R. pumilio. It is suggested that coexistence maybe based on a sixth mechanism, seasonal variation in resource abundance and a tradeoff of maintenance efficiency versus foraging efficiency. Further, it appears that R. pumilio is more efficient at maintaining harvest potential, not by maintaining high consumer biomass, but rather by having a high int
Observation of Extended Red Emission (ERE) in the halo of M82
J. -M. Perrin,S. Darbon,J. -P. Sivan
Physics , 1995,
Abstract: Low-dispersion spectra have been obtained from 4000 to 9600 \AA~along the axis and across the dusty halo of the galaxy M82. The spectra of the halo are explained in terms of scattering of the galactic light by dust grains: when divided by the spectrum of the galaxy, they reveal a broad emission band, similar to, although wider than the bump of Extended Red Emission (ERE) commonly observed in galactic reflection nebulae. The feature is particularly well marked in the filamentary parts of the halo. This is the first detection of ERE outside of our Galaxy.
Pupil remapping for high contrast astronomy: results from an optical testbed
T. Kotani,S. Lacour,G. Perrin,G. Robertson,P. Tuthill
Physics , 2009, DOI: 10.1364/OE.17.001925
Abstract: The direct imaging and characterization of Earth-like planets is among the most sought-after prizes in contemporary astrophysics, however current optical instrumentation delivers insufficient dynamic range to overcome the vast contrast differential between the planet and its host star. New opportunities are offered by coherent single mode fibers, whose technological development has been motivated by the needs of the telecom industry in the near infrared. This paper presents a new vision for an instrument using coherent waveguides to remap the pupil geometry of the telescope. It would (i) inject the full pupil of the telescope into an array of single mode fibers, (ii) rearrange the pupil so fringes can be accurately measured, and (iii) permit image reconstruction so that atmospheric blurring can be totally removed. Here we present a laboratory experiment whose goal was to validate the theoretical concepts underpinning our proposed method. We successfully confirmed that we can retrieve the image of a simulated astrophysical object (in this case a binary star) though a pupil remapping instrument using single mode fibers.
Wall effects on granular heap stability
S. Courrech du Pont,P. Gondret,B. Perrin,M. Rabaud
Physics , 2002, DOI: 10.1209/epl/i2003-00156-5
Abstract: We investigate the effects of lateral walls on the angle of movement and on the angle of repose of a granular pile. Our experimental results for beads immersed in water are similar to previous results obtained in air and to recent numerical simulations. All of these results, showing an increase of pile angles with a decreasing gap width, are explained by a model based on the redirection of stresses through the granular media. Two regimes are observed depending on the bead diameter. For large beads, the range of wall effects corresponds to a constant number of beads whereas it corresponds to a constant characteristic length for small beads as they aggregate via van der Waals forces.
Granular Avalanches in Fluids
S. Courrech du Pont,P. Gondret,B. Perrin,M. Rabaud
Physics , 2002, DOI: 10.1103/PhysRevLett.90.044301
Abstract: Three regimes of granular avalanches in fluids are put in light depending on the Stokes number St which prescribes the relative importance of grain inertia and fluid viscous effects, and on the grain/fluid density ratio r. In gas (r >> 1 and St > 1, e.g., the dry case), the amplitude and time duration of avalanches do not depend on any fluid effect. In liquids (r ~ 1), for decreasing St, the amplitude decreases and the time duration increases, exploring an inertial regime and a viscous regime. These regimes are described by the analysis of the elementary motion of one grain.
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