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Search Results: 1 - 10 of 475 matches for " Josiane Warszawski "
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Boundary behavior of the Kobayashi distance in pseudoconvex Reinhardt domains
Tomasz Warszawski
Mathematics , 2011, DOI: 10.1307/mmj/1347040260
Abstract: We prove that the Kobayashi distance near boundary of a pseudoconvex Reinhardt domain $D$ increases asymptotically at most like $-\log d_D+C$. Moreover, for boundary points from $\text{int}\bar{D}$ the growth does not exceed $1/2\log(-\log d_D)+C$. The lower estimate by $-1/2\log d_D+C$ is obtained under additional assumptions of $\mathcal C^1$-smoothness of a domain and a non-tangential convergence.
Extension of holomorphic functions onto a special domain
Tomasz Warszawski
Mathematics , 2012,
Abstract: We present a modified version of the Arakelyan's result: a relationship between holomorphic extension of a holomorphic function on the unit disc onto the domain $\mathbb C\setminus[1,\infty)$ and its Taylor coefficients' interpolation.
(Weak) $m$-extremals and $m$-geodesics
Tomasz Warszawski
Mathematics , 2014, DOI: 10.1080/17476933.2014.998659
Abstract: We present a collection of results on (weak) $m$-extremals and $m$-geodesics, concerning general properties, the planar case, quasi-balanced pseudoconvex domains, complex ellipsoids, the Euclidean ball and boundary properties. We prove $3$-geodesity of $3$-extremals in the Euclidean ball. Equivalence of weak $m$-extremality and $m$-extremality in some class of convex complex ellipsoids, containing symmetric ones and $\mathcal C^2$-smooth ones is showed. Moreover, first examples of $3$-extremals being not $3$-geodesics in convex domains are given.
Feasibility of Early Infant Diagnosis of HIV in Resource-Limited Settings: The ANRS 12140-PEDIACAM Study in Cameroon
Mathurin C. Tejiokem, Albert Faye, Ida C. Penda, Georgette Guemkam, Francis Ateba Ndongo, Gisèle Chewa, Claire Rekacewicz, Dominique Rousset, Anfumbom Kfutwah, Pascal Boisier, Josiane Warszawski, the ARNS 12140-PEDIACAM study group
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0021840
Abstract: Background Early infant diagnosis (EID) of HIV is a key-point for the implementation of early HAART, associated with lower mortality in HIV-infected infants. We evaluated the EID process of HIV according to national recommendations, in urban areas of Cameroon. Methods/Findings The ANRS12140-Pediacam study is a multisite cohort in which infants born to HIV-infected mothers were included before the 8th day of life and followed. Collection of samples for HIV DNA/RNA-PCR was planned at 6 weeks together with routine vaccination. The HIV test result was expected to be available at 10 weeks. A positive or indeterminate test result was confirmed by a second test on a different sample. Systematic HAART was offered to HIV-infected infants identified. The EID process was considered complete if infants were tested and HIV results provided to mothers/family before 7 months of age. During 2007–2009, 1587 mother-infant pairs were included in three referral hospitals; most infants (n = 1423, 89.7%) were tested for HIV, at a median age of 1.5 months (IQR, 1.4–1.6). Among them, 51 (3.6%) were HIV-infected. Overall, 1331 (83.9%) completed the process by returning for the result before 7 months (median age: 2.5 months (IQR, 2.4–3.0)). Incomplete process, that is test not performed, or result of test not provided or provided late to the family, was independently associated with late HIV diagnosis during pregnancy (adjusted odds ratio (aOR) = 1.8, 95%CI: 1.1 to 2.9, p = 0.01), absence of PMTCT prophylaxis (aOR = 2.4, 95%CI: 1.4 to 4.3, p = 0.002), and emergency caesarean section (aOR = 2.5, 95%CI: 1.5 to 4.3, p = 0.001). Conclusions In urban areas of Cameroon, HIV-infected women diagnosed sufficiently early during pregnancy opt to benefit from EID whatever their socio-economic, marital or disclosure status. Reduction of non optimal diagnosis process should focus on women with late HIV diagnosis during pregnancy especially if they did not receive any PMTCT, or if complications occurred at delivery.
Perinatal acquisition of drug-resistant HIV-1 infection: mechanisms and long-term outcome
Constance Delaugerre, Marie-Laure Chaix, Stephane Blanche, Josiane Warszawski, Dorine Cornet, Catherine Dollfus, Veronique Schneider, Marianne Burgard, Albert Faye, Laurent Mandelbrot, Roland Tubiana, Christine Rouzioux, the ANRS French Perinatal Cohort
Retrovirology , 2009, DOI: 10.1186/1742-4690-6-85
Abstract: We studied HIV-1-infected infants born between 01 January 1997 and 31 December 2004 and enrolled in the ANRS-EPF cohort. HIV-1-RNA and HIV-1-DNA samples obtained perinatally from the newborn and mother were subjected to population-based and clonal analyses of drug resistance. If positive, serial samples were obtained from the child for resistance testing.Ninety-two HIV-1-infected infants were born during the study period. Samples were obtained from 32 mother-child pairs and from another 28 newborns. Drug resistance was detected in 12 newborns (20%): drug resistance to nucleoside reverse transcriptase inhibitors was seen in 10 cases, non-nucleoside reverse transcriptase inhibitors in two cases, and protease inhibitors in one case. For 9 children, the detection of the same resistance mutations in mothers' samples (6 among 10 available) and in newborn lymphocytes (6/8) suggests that the newborn was initially infected by a drug-resistant strain. Resistance variants were either transmitted from mother-to-child or selected during subsequent temporal exposure under suboptimal perinatal prophylaxis. Follow-up studies of the infants showed that the resistance pattern remained stable over time, regardless of antiretroviral therapy, suggesting the early cellular archiving of resistant viruses. The absence of resistance in the mother of the other three children (3/10) and neonatal lymphocytes (2/8) suggests that the newborns were infected by a wild-type strain without long-term persistence of resistance when suboptimal prophylaxis was stopped.This study confirms the importance of early resistance genotyping of HIV-1-infected newborns. In most cases (75%), drug resistance was archived in the cellular reservoir and persisted during infancy, with or without antiretroviral treatment. This finding stresses the need for effective antiretroviral treatment of pregnant women.Mother-to-child transmission (MTCT) of HIV-1 mainly occurs during the third trimester of pregnancy or at delivery
Association between Prenatal Exposure to Antiretroviral Therapy and Birth Defects: An Analysis of the French Perinatal Cohort Study (ANRS CO1/CO11)
Jeanne Sibiude ,Laurent Mandelbrot,Stéphane Blanche,Jér?me Le Chenadec,Naima Boullag-Bonnet,Albert Faye,Catherine Dollfus,Roland Tubiana,Damien Bonnet,Nathalie Lelong,Babak Khoshnood,Josiane Warszawski
PLOS Medicine , 2014, DOI: 10.1371/journal.pmed.1001635
Abstract: Background Antiretroviral therapy (ART) has major benefits during pregnancy, both for maternal health and to prevent mother-to-child transmission of HIV. Safety issues, including teratogenic risk, need to be evaluated. We estimated the prevalence of birth defects in children born to HIV-infected women receiving ART during pregnancy, and assessed the independent association of birth defects with each antiretroviral (ARV) drug used. Methods and Findings The French Perinatal Cohort prospectively enrolls HIV-infected women delivering in 90 centers throughout France. Children are followed by pediatricians until 2 y of age according to national guidelines. We included 13,124 live births between 1994 and 2010, among which, 42% (n = 5,388) were exposed to ART in the first trimester of pregnancy. Birth defects were studied using both European Surveillance of Congenital Anomalies (EUROCAT) and Metropolitan Atlanta Congenital Defects Program (MACDP) classifications; associations with ART were evaluated using univariate and multivariate logistic regressions. Correction for multiple comparisons was not performed because the analyses were based on hypotheses emanating from previous findings in the literature and the robustness of the findings of the current study. The prevalence of birth defects was 4.4% (95% CI 4.0%–4.7%), according to the EUROCAT classification. In multivariate analysis adjusting for other ARV drugs, maternal age, geographical origin, intravenous drug use, and type of maternity center, a significant association was found between exposure to zidovudine in the first trimester and congenital heart defects: 2.3% (74/3,267), adjusted odds ratio (AOR) = 2.2 (95% CI 1.3–3.7), p = 0.003, absolute risk difference attributed to zidovudine +1.2% (95% CI +0.5; +1.9%). Didanosine and indinavir were associated with head and neck defects, respectively: 0.5%, AOR = 3.4 (95% CI 1.1–10.4), p = 0.04; 0.9%, AOR = 3.8 (95% CI 1.1–13.8), p = 0.04. We found a significant association between efavirenz and neurological defects (n = 4) using the MACDP classification: AOR = 3.0 (95% CI 1.1–8.5), p = 0.04, absolute risk +0.7% (95% CI +0.07%; +1.3%). But the association was not significant using the less inclusive EUROCAT classification: AOR = 2.1 (95% CI 0.7–5.9), p = 0.16. No association was found between birth defects and lopinavir or ritonavir with a power >85% for an odds ratio of 1.5, nor for nevirapine, tenofovir, stavudine, or abacavir with a power >70%. Limitations of the present study were the absence of data on termination of pregnancy, stillbirths, tobacco and
Low Birth Weight in Perinatally HIV-Exposed Uninfected Infants: Observations in Urban Settings in Cameroon
Casimir Ledoux Sofeu, Josiane Warszawski, Francis Ateba Ndongo, Ida Calixte Penda, Suzie Tetang Ndiang, Georgette Guemkam, Nicaise Makwet, Félicité Owona, Anfumbom Kfutwah, Patrice Tchendjou, Ga?tan Texier, Maurice Tchuente, Albert Faye, Mathurin Cyrille Tejiokem, The ANRS-PEDIACAM study group
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0093554
Abstract: Background The consequences of maternal HIV infection for fetal growth are controversial. Here, we estimated the frequency of small for gestational age and gender (SGAG) among neonates born to HIV-infected or uninfected mothers and assessed the contribution, if any, of maternal HIV to the risk of SGAG. Methods The data used were obtained from the ANRS-Pediacam cohort in Cameroon. Pairs of newborns, one to a HIV-infected mother and the other to an uninfected mother, were identified during the first week of life, and matched on gender and recruitment site from 2007–2010. SGAG was defined in line with international recommendations as a birth weight Z-score adjusted for gestational age at delivery and gender more than two standard deviations below the mean (?2SD). Considering the matched design, logistic regression modeling was adjusted on site and gender to explore the effect of perinatal HIV exposure on SGAG. Results Among the 4104 mother-infant pairs originally enrolled, no data on birth weight and/or gestational age were available for 108; also, 259 were twins and were excluded. Of the remaining 3737 mother-infant pairs, the frequency of SGAG was 5.3% (95%CI: 4.6–6.0), and was significantly higher among HIV-infected infants (22.4% vs. 6.3%; p<.001) and lower among HIV-unexposed uninfected infants (3.5% vs. 6.3%; p<.001) than among HIV-exposed uninfected infants. Similarly, SGAG was significantly more frequent among HIV-infected infants (aOR: 4.1; 2.0–8.1) and less frequent among HIV-unexposed uninfected infants (aOR: 0.5; 0.4–0.8) than among HIV-exposed uninfected infants. Primiparity (aOR: 1.9; 1.3–2.7) and the presence of any disease during pregnancy (aOR: 1.4; 1.0–2.0) were identified as other contributors to SGAG. Conclusion Maternal HIV infection was independently associated with SGAG for HIV-exposed uninfected infants. This provides further evidence of the need for adapted monitoring of pregnancy in HIV-infected women, especially if they are symptomatic, to minimize additional risk factors for SGAG.
Superfluid vortex unpinning as a coherent noise process, and the scale invariance of pulsar glitches
Andrew Melatos,Lila Warszawski
Physics , 2009, DOI: 10.1088/0004-637X/700/2/1524
Abstract: The scale-invariant glitch statistics observed in individual pulsars (exponential waiting-time and power-law size distributions) are consistent with a critical self-organization process, wherein superfluid vortices pin metastably in macroscopic domains and unpin collectively via nearest-neighbor avalanches. Macroscopic inhomogeneity emerges naturally if pinning occurs at crustal faults. If, instead, pinning occurs at lattice sites and defects, which are macroscopically homogeneous, we show that an alternative, noncritical self-organization process operates, termed coherent noise, wherein the global Magnus force acts uniformly on vortices trapped in a range of pinning potentials and undergoing thermal creep. It is found that vortices again unpin collectively, but not via nearest-neighbor avalanches, and that, counterintuitively, the resulting glitch sizes are scale invariant, in accord with observational data. A mean-field analytic theory of the coherent noise process, supported by Monte-Carlo simulations, yields a power-law size distribution, between the smallest and largest glitch, with exponent $a$ in the range $-2\leq a \leq 0$. When the theory is fitted to data from the nine most active pulsars, including the two quasiperiodic glitchers PSR J0537$-$6910 and PSR J0835$-$4510, it directly constrains the distribution of pinning potentials in the star, leading to two conclusions: (i) the potentials are broadly distributed, with the mean comparable to the standard deviation; and (ii) the mean potential decreases with characteristic age. An observational test is proposed to discriminate between nearest-neighbor avalanches and coherent noise.
A Cellular Automaton Model of Pulsar Glitches
L. Warszawski,A. Melatos
Physics , 2008, DOI: 10.1111/j.1365-2966.2008.13662.x
Abstract: A cellular automaton model of pulsar glitches is described, based on the superfluid vortex unpinning paradigm. Recent analyses of pulsar glitch data suggest that glitches result from scale-invariant avalanches \citep{Melatos07a}, which are consistent with a self-organized critical system (SOCS). A cellular automaton provides a computationally efficient means of modelling the collective behaviour of up to $10^{16}$ vortices in the pulsar interior, whilst ensuring that the dominant aspects of the microphysics are not lost. The automaton generates avalanche distributions that are qualitatively consistent with a SOCS and with glitch data. The probability density functions of glitch sizes and durations are power laws, and the probability density function of waiting times between successive glitches is Poissonian, consistent with statistically independent events. The output of the model depends on the physical and computational paramters used. The fitted power law exponents for the glitch sizes ($a$) and durations ($b$) decreases as the strength of the vortex pinning increases. Similarly the exponents increase as the fraction of vortices that are pinned decreases. For the physical and computational parameters considered, one finds $-4.3\leq a \leq -2.0$ and $-5.5\leq b\leq -2.2$, and mean glitching rates in the range $0.0023\leq\lambda\leq0.13\$ in units of inverse time.
Gravitational-wave bursts and stochastic background from superfluid vortex avalanches during pulsar glitches
L. Warszawski,A. Melatos
Physics , 2012, DOI: 10.1111/j.1365-2966.2012.20977.x
Abstract: The current-quadrupole gravitational-wave signal emitted during the spin-up phase of a pulsar glitch is calculated from first principles by modeling the vortex dynamics observed in recent Gross-Pitaevskii simulations of pinned, decelerating quantum condensates. Homogeneous and inhomogeneous unpinning geometries, representing creep- and avalanche-like glitches, provide lower and upper bounds on the gravitational wave signal strength respectively. The signal arising from homogeneous glitches is found to scale with the square root of glitch size, whereas the signal from inhomogeneous glitches scales proportional to glitch size. The signal is also computed as a function of vortex travel distance and stellar angular velocity. Convenient amplitude scalings are derived as functions of these parameters. For the typical astrophysical situation, where the glitch duration (in units of the spin period) is large compared to the vortex travel distance (in units of the stellar radius), an individual glitch from an object $1\,\rm{kpc}$ from Earth generates a wave strain of $10^{-24} [(\Delta\omega/\omega) / 10^{-7}] (\omega/10^2 \rm{rad s}^{-1})^3 (\Delta r / 10^{-2} \rm{m})^{-1}$, where $\Delta r$ is the average distance travelled by a vortex during a glitch, $\Delta\omega/\omega$ is the fractional glitch size, and $\omega$ is the pulsar angular velocity. The non-detection of a signal from the 2006 Vela glitch in data from the fifth science run conducted by the Laser Interferometer Gravitational-Wave Observatory implies that the glitch duration exceeds $\sim 10^{-4}\,\rm{ms}$. This represents the first observational lower bound on glitch duration to be obtained.
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