761 research outputs found

    Repeated games for eikonal equations, integral curvature flows and non-linear parabolic integro-differential equations

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    The main purpose of this paper is to approximate several non-local evolution equations by zero-sum repeated games in the spirit of the previous works of Kohn and the second author (2006 and 2009): general fully non-linear parabolic integro-differential equations on the one hand, and the integral curvature flow of an interface (Imbert, 2008) on the other hand. In order to do so, we start by constructing such a game for eikonal equations whose speed has a non-constant sign. This provides a (discrete) deterministic control interpretation of these evolution equations. In all our games, two players choose positions successively, and their final payoff is determined by their positions and additional parameters of choice. Because of the non-locality of the problems approximated, by contrast with local problems, their choices have to "collect" information far from their current position. For integral curvature flows, players choose hypersurfaces in the whole space and positions on these hypersurfaces. For parabolic integro-differential equations, players choose smooth functions on the whole space

    Are dentists enough aware of infectious risk associated with dental unit waterlines?

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    Environmental conditions in DU encourage biofilm development. This biofilm may represent a risk for patients and dental staff exposed to water and aerosols generated during dental cares, particularly for immunocompromised persons. A survey was conducted on the 175 dental surgeons of the department of Vienne (France) to investigate the motivations of dental practitioners to renew their DU, their awareness levels with respect to infectious risks related to water circulating within DU, and methods used for the maintenance of DU waterlines. These dentists were only partially aware of the need for maintaining DU waterlines. For this maintaining, chemical treatments and purges of pipes were carried out by 88% and 91.5% of dentists respectively ; chemical treatments were usually on a continous mode and dentists seemed to have complete confidence in their DU supplier regarding the choice and the use of chemical treatments. Flushes were performed only once per day in most cases (63%). This survey also highlighted that dentists were not enough aware of water related infectous risk, even though 68% estimated that the development of a biofilm within DU waterlines was an actual risk. Finally, very positively, dentists strongly indicated their wish to be more informed regarding all these risks. Although these results are based on a relatively small sample, corresponding to dentists of a French department, they clearly suggest that awareness of dental surgeons is still insufficient and must be performed to permit an effective prevention of infectious risk related to DU waterlines

    Geometric approach to nonvariational singular elliptic equations

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    In this work we develop a systematic geometric approach to study fully nonlinear elliptic equations with singular absorption terms as well as their related free boundary problems. The magnitude of the singularity is measured by a negative parameter (γ1)(\gamma -1), for 0<γ<10 < \gamma < 1, which reflects on lack of smoothness for an existing solution along the singular interface between its positive and zero phases. We establish existence as well sharp regularity properties of solutions. We further prove that minimal solutions are non-degenerate and obtain fine geometric-measure properties of the free boundary F={u>0}\mathfrak{F} = \partial \{u > 0 \}. In particular we show sharp Hausdorff estimates which imply local finiteness of the perimeter of the region {u>0}\{u > 0 \} and Hn1\mathcal{H}^{n-1} a.e. weak differentiability property of F\mathfrak{F}.Comment: Paper from D. Araujo's Ph.D. thesis, distinguished at the 2013 Carlos Gutierrez prize for best thesis, Archive for Rational Mechanics and Analysis 201

    The OSACA Database and a Kinematic Analysis of Stars in the Solar Neighborhood

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    We transformed radial velocities compiled from more than 1400 published sources, including the Geneva--Copenhagen survey of the solar neighborhood (CORAVEL-CfA), into a uniform system based on the radial velocities of 854 standard stars in our list. This enabled us to calculate the average weighted radial velocities for more than 25~000 HIPPARCOS stars located in the local Galactic spiral arm (Orion arm) with a median error of +-1 km/s. We use these radial velocities together with the stars' coordinates, parallaxes, and proper motions to determine their Galactic coordinates and space velocities. These quantities, along with other parameters of the stars, are available from the continuously updated Orion Spiral Arm CAtalogue (OSACA) and the associated database. We perform a kinematic analysis of the stars by applying an Ogorodnikov-Milne model to the OSACA data. The kinematics of the nearest single and multiple main-sequence stars differ substantially. We used distant (r\approx 0.2 kpc) stars of mixed spectral composition to estimate the angular velocity of the Galactic rotation -25.7+-1.2 km/s/kpc, and the vertex deviation,l=13+-2 degrees, and detect a negative K effect. This negative K effect is most conspicuous in the motion of A0-A5 giants, and is equal to K=-13.1+-2.0 km/s/kpc.Comment: 16 pages, 8 figure

    Improvement of the CORS method for Cepheids radii determination based on Stromgren photometry

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    In this paper we present a modified version of the CORS method based on a new calibration of the Surface Brightness function in the Stromgren photometric system. The method has been tested by means of synthetic light and radial velocity curves derived from nonlinear pulsation models. Detailed simulations have been performed to take into account the quality of real observed curves as well as possible shifts between photometric and radial velocity data. The method has been then applied to a sample of Galactic Cepheids with Stromgren photometry and radial velocity data to derive the radii and a new PR relation. As a result we find log R = (1.19 +- 0.09) + (0.74 +- 0.11) log P (r.m.s=0.07). The comparison between our result and previous estimates in the literature is satisfactory. Better results are expected from the adoption of improved model atmosphere grids.Comment: 13 pages including 12 postscript figures and 3 jpeg figures; accepted for publication on A&

    Applicability and precautions of use of liver injury biomarker FibroTest. A reappraisal at 7 years of age

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    <p>Abstract</p> <p>Background</p> <p>FibroTest (FT) is a validated biomarker of fibrosis. To assess the applicability rate and to reduce the risk of false positives/negatives (RFPN), security algorithms were developed. The aims were to estimate the prevalence of RFPN and of proven failures, and to identify factors associated with their occurrences.</p> <p>Methods</p> <p>Four populations were studied: 954 blood donors (P1), 7,494 healthy volunteers (P2), 345,695 consecutive worldwide sera (P3), including 24,872 sera analyzed in a tertiary care centre (GHPS) (P4). Analytical procedures of laboratories with RFPN > 5% and charts of P4 patients in with RFPN were reviewed.</p> <p>Results</p> <p>The prevalence of RFPN was 0.52% (5/954; 95%CI 0.17-1.22) in P1, 0.51% (38/7494; 0.36-0.70) in P2, and 0.97% (3349/345695; 0.94-1.00) in P3. Three a priori high-risk populations were confirmed: 1.97% in P4, 1.77% in HIV centre and 2.61% in Sub-Saharan origin subjects. RFPN was mostly associated with low haptoglobin (0.46%), and high apolipoproteinA1 (0.21%). A traceability study of a P3 laboratory with RFPFN > 5% permitted to correct analytical procedures.</p> <p>Conclusion</p> <p>The mean applicability rate of Fibrotest was 99.03%. Independent factors associated with the high risk of false positives/negatives were HIV center, subSaharan origin, and a tertiary care reference centre, although the applicability rate remained above 97%.</p

    Technical design and performance of the NEMO3 detector

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    The development of the NEMO3 detector, which is now running in the Frejus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more than ten years ago. The NEMO3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.Comment: Preprint submitted to Nucl. Instrum. Methods A Corresponding author: Corinne Augier ([email protected]

    Goos-H\"{a}nchen and Imbert-Fedorov shifts of polarized vortex beams

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    We study, analytically and numerically, reflection and transmission of an arbitrarily polarized vortex beam on an interface separating two dielectric media and derive general expressions for linear and angular Goos-Hanchen and Imbert-Fedorov shifts. We predict a novel vortex-induced Goos-Hanchen shift, and also reveal direct connection between the spin-induced angular shifts and the vortex-induced linear shifts.Comment: 4 pages, 2 figures, to appear in Optics Letter

    THU0275 SEVERE PREECLAMPSIA RELATED TO ANTIPHOSPHOLIPID SYNDROME: AN EUROPEAN STUDY OF 40 WOMEN

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    Background:One of the 3 features of obstetrical antiphospholipid syndrome (APS) is severe preeclampsia (PE). Its time of occurrence, the associated risk of thromboses and systemic lupus erythematosus (SLE) have not been reported yet.Objectives:We analyzed severe PE in a series of women with APS.Methods:We retrospectively collected data of female patients from 5 French internal medicine and 1 Italian rheumatology units. Inclusion criteria were: a severe PE/eclampsia(1), that occurred before 34 weeks of gestation (WG) in patients who met the APS classification criteria(2).Results:40 patients were enrolled (Table 1). Because of known APS/positive aPL/previous obstetrical complications, 23(57.5%) patients were treated during the index PE: 4 with low dose aspirin (LDA), 4 with low molecular weight heparin (LMWH), and 15 with a combination of both. 7 patients were also treated with hydroxychloroquine, 8 with corticosteroids and 3 with immunosuppressants. 17(42.5%) patients received no treatment. 24(60%) live births were observed. During a follow-up period of 3 years, 26(65%) patients had at least 1 new pregnancy, with a total of 38 pregnancies which resulted in 33(86.8%) live births. 57.5% pregnancies who resulted in live births occurred without any maternal or fetal complications. All 26 patients who had at least 1 pregnancy after index PE were treated with LDA; LMWH was given at prophylactic and therapeutic dosage in 13(50%) patients, respectively. No patient experienced 3 consecutive miscarriages.Table 1.40 APS patients with severe PEOverall features (n, %)Patients40 (100)Age at PE, (median, IQR)30.5 (27-33)PE term, WG (median, IQR)25.5 (23-29) Live births24 (60) Birth term, WG (median, IQR)25.5 (23.7-30.3) Associated SLE12 (30)Maternal complications (n, %)25 (62.5) HELLP18 (45) E6 (15) CAPS3 (7.5) Placental abruptions3 (7.5)Fetal complications (n, %)31 (77.5) IUGR18 (45) IUFD11 (2.5) Preterm delivery22 (55)Obstetrical history (n, %) Primiparous21 (52.5) Index PE before APS12 (30)Thrombosis (n, %) Thrombosis before PE index14 (35.0) Thrombosis after PE index2 (5.0)Abs at APS diagnosis (n, %) aPL triple positivity21 (52.5) IgG/IgM anti-cardiolipin34 (85.0) IgG/IgM anti-β2GPI25 (62.5) LAC33 (82.5)Legend to Table 1:PE: preeclampsia; APS: antiphospholipid syndrome; IQR: interquartile range; WG: weeks of gestation; SLE: systemic lupus erythematosus; HELLP: Hemolysis, elevated liver enzymes, low platelet; E: eclampsia; CAPS: catastrophic APS; IUGR: intrauterine growth restriction; IUFD: intrauterine fetal death; CHB: congenital atrioventricular block; aPL: antiphospholipid antibodies; LAC: lupus anticoagulant.Conclusion:Among the APS criteria, "3 consecutive miscarriages criterion" was not found. The majority of patients also experienced thrombosis and SLE before the index PE.References:[1]Diagnosis and Management of preeclampsia and eclampsia. International Journal of Gynecology &Obestetrics 2002;77:67-75.[2]Miyakis S, et al. International consensus statement on an update of the classification criteria for definite antiphospholipid syndrome (APS). J Thromb Haemost 2006;4:295e 306.Disclosure of Interests:Maddalena Larosa: None declared, Nathalie Morel: None declared, Meriem BELHOCINE: None declared, Amelia Ruffatti: None declared, Nicolas Martin Silva: None declared, Romain Paul: None declared, Luc Mouthon: None declared, Michel DREYFUS: None declared, Jean-Charles PIETTE: None declared, Odile Souchaud-Debouverie: None declared, Catherine Deneux-Tharaux: None declared, Vassilis Tsatsaris: None declared, Emmanuelle Pannier: None declared, Gaêlle Guettrot Imbert: None declared, Véronique LE GUERN Grant/research support from: UCB for GR2 study (to our institution), Andrea Doria Consultant of: GSK, Pfizer, Abbvie, Novartis, Ely Lilly, Speakers bureau: UCB pharma, GSK, Pfizer, Janssen, Abbvie, Novartis, Ely Lilly, BMS, Nathalie Costedoat-Chalumeau Grant/research support from: UCB to my institutio

    Structure and Evolution of Nearby Stars with Planets. I. Short-Period Systems

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    Using the Yale stellar evolution code, we have calculated theoretical models for nearby stars with planetary-mass companions in short-period nearly circular orbits: 51 Pegasi, Tau Bootis, Upsilon Andromedae, Rho Cancri, and Rho Coronae Borealis. We present tables listing key stellar parameters such as mass, radius, age, and size of the convective envelope as a function of the observable parameters (luminosity, effective temperature, and metallicity), as well as the unknown helium fraction. For each star we construct best models based on recently published spectroscopic data and the present understanding of galactic chemical evolution. We discuss our results in the context of planet formation theory, and, in particular, tidal dissipation effects and stellar metallicity enhancements.Comment: 48 pages including 13 tables and 5 figures, to appear in Ap
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