Duality between Topologically Massive and Self-Dual models

We show that, with the help of a general BRST symmetry, different theories in 3 dimensions can be connected through a fundamental topological field theory related to the classical limit of the Chern-Simons model.Comment: 13 pages, LaTe

Stability of 3D Cubic Fixed Point in Two-Coupling-Constant \phi^4-Theory

For an anisotropic euclidean $\phi^4$-theory with two interactions [u (\sum_{i=1^M {\phi}_i^2)^2+v \sum_{i=1}^M \phi_i^4] the $\beta$-functions are calculated from five-loop perturbation expansions in $d=4-\varepsilon$ dimensions, using the knowledge of the large-order behavior and Borel transformations. For $\varepsilon=1$, an infrared stable cubic fixed point for $M \geq 3$ is found, implying that the critical exponents in the magnetic phase transition of real crystals are of the cubic universality class. There were previous indications of the stability based either on lower-loop expansions or on less reliable Pad\'{e approximations, but only the evidence presented in this work seems to be sufficently convincing to draw this conclusion.Comment: Author Information under http://www.physik.fu-berlin.de/~kleinert/institution.html . Paper also at http://www.physik.fu-berlin.de/~kleinert/kleiner_re250/preprint.htm

Magnetocaloric effect and improved relative cooling power in (La0.7Sr0.3MnO3/SrRuO3) superlattices

Magnetic properties of a series of (La0.7Sr0.3MnO3/SrRuO3) superlattices, where the SrRuO3 layer thickness is varying, are examined. A room-temperature magnetocaloric effect is obtained owing to the finite size effect which reduces the TC of La0.7Sr0.3MnO3 layers. While the working temperature ranges are enlarged,, -DeltaSmax values remains similar to the values in polycrystalline La0.7Sr0.3MnO3. Consequently, the relative cooling powers are significantly improved, the microscopic mechanism of which is related to the effect of the interfaces at La0.7Sr0.3MnO3/SrRuO3 and higher nanostructural disorder. This study indicates that artificial oxide superlattices/multilayers might provide an alternative pathway in searching for efficient room-temperature magnetic refrigerators for (nano)microscale systems.Comment: 14^pages, 3 figures, Submitted to J. Phys. Cond. Ma

Actualités sur les co-infections VIH–VHC

Objectives To evaluate the incidence of HIV–HCV co-infections and analyse the outcome in co-infected patients. Epidemiology. Effects of antivirals The prevalence of the co-infection by the HCV thus varies from 10 to 14% on subjects who have sexual behaviors at risk at 80 or 90% on users of drug IV. Numerous studies showed that the infection by the HIV made worse the natural history of the infection by the HCV [J Acquir Immune Defic Syndr 6 1993 602–610; J Hepatol 28 1998 945–950]. On the other hand, the studies which endeavoured to appreciate the effect of the antiretroviral therapeutics on the natural history of the chronic hepatitis C, on the co-infected patients, are more discussed. In cohorts of big size, it was demonstrated that the hepatic mortality increased with the exposure to antiretrovirals. However, the duration of the antiretroviral treatment also reports the more important survival of the patients, which distorts credibly the figures. The effect of the infection by the HCV on the progress of the disease with HIV is more discussed. The patients infected by the HIV, in any case, have to benefit from the research for a co-infection by the viruses of hepatitis B and C (HBV and HCV). This screening must be renewed every year, in particular on the drug addicts patients or presenting behaviors at risk. Viral replication The research of a viral replication, must be implemented for any confirmed positive HCV serology. The research of the HCV RNA needs ultrasensitive techniques of molecular biology which allow a qualitative detection andor a quantification of the viral genome (viral load). The techniques of last generation of real-time PCR combine both approaches (detection and quantification). The viral load HCV is not correlated to the degree of hepatic disease and does not predict the severity of the hepatic disease, contrary to the correlation demonstrated in the infection by the HIV. On the other hand, it can be a predictive factor in the response to the treatment. The pretherapeutic check-up also includes a determination of the viral genotype because a strong involvement in the response to the treatment was clearly demonstrated. Hepatic fibrosis The hepatic fibrosis must be estimated on patients having a chronic hepatitis because it conditions the prognosis and the treatment of the hepatitis. The anatomopathological study after hepatic biopsy (DHB) remains the reference method. Recently, the development of non invasive methods of measure of the hepatic fibrosis improved the care of hepatitis C, notably the blood tests (fibrotest BioPredictive Paris, fibrometer BLS Angers) and physical measures as the impulsional elastometry (Fibroscan® Echosens) which substitutes more and more in practice to the draining hepatic biopsy. Treatment Numerous studies now validated the treatment associating interferon pegilated and ribavirine as the reference treatment on the co-infected patients HIV/HCV. This treatment involves a high virological response going from 14 to 36% in the patients infected by a genotype 1 and 2 and from 43 to 73% in the patients infected by a genotype 2 or 3. The duration of the treatment is 48 weeks. As well as usual virological factors on the mono-infected patients (genotype, viral load), the rate of CD4 is one of the best predictive factors with a good response. Many hopes go towards the new molecules in development (inhibitors of protease), inhibitors of polymerase), with promising results on the mono-infected patients. However, the toxicity of these molecules is not very well known at the moment in the co-infected patients. It is thus necessary to perform trials in this group of patient, by watching very carefully the toxicity of the therapeutic associations