Influence of nanosecond repetitively pulsed discharges on the stability of a swirled propane/air burner representative of an aeronautical combustor.

This paper reports on an experimental study of the influence of a nanosecond repetitively pulsed spark discharge on the stability domain of a propane/air flame. This flame is produced in a lean premixed swirled combustor representative of an aeronautical combustion chamber. The lean extinction limits of the flame produced without and with plasma are determined and compared. It appears that only a low mean discharge power is necessary to increase the flame stability domain. Lastly, the effects of several parameters (pulse repetition frequency, global flowrate, electrode location) are studied.

Isometric fluctuation relations for equilibrium states with broken symmetry.

We derive a set of isometric fluctuation relations, which constrain the order parameter fluctuations in finite-size systems at equilibrium and in the presence of a broken symmetry. These relations are exact and should apply generally to many condensed-matter physics systems. Here, we establish these relations for magnetic systems and nematic liquid crystals in a symmetry-breaking external field, and we illustrate them on the Curie-Weiss and the XY models. Our relations also have implications for spontaneous symmetry breaking, which are discussed.

Energy versus information based estimations of dissipation using a pair of magnetic colloidal particles.

Using the framework of stochastic thermodynamics, we present an experimental study of a doublet of magnetic colloidal particles that is manipulated by a time-dependent magnetic field. Because of hydrodynamic interactions, each bead experiences a state-dependent friction, which we characterize using a hydrodynamic model. In this work, we compare two estimates of the dissipation in this system: the first one is energy based since it relies on the measured interaction potential, while the second one is information based since it uses only the information content of the trajectories. While the latter only offers a lower bound of the former, we find it to be simple to implement and of general applicability to more complex systems.

Non-invasive estimation of dissipation from non-equilibrium fluctuations in chemical reactions.

We show how to extract an estimate of the entropy production from a sufficiently long time series of stationary fluctuations of chemical reactions. This method, which is based on recent work on fluctuation theorems, is direct, non-invasive, does not require any knowledge about the underlying dynamics and is applicable even when only partial information is available. We apply it to simple stochastic models of chemical reactions involving a finite number of states, and for this case, we study how the estimate of dissipation is affected by the degree of coarse-graining present in the input data.

Measuring colloidal forces with the magnetic chaining technique.

In 1994 Leal Calderon et al. (Phys. Rev. Lett. 72, 2959 (1994)) introduced the magnetic chaining technique to directly probe the force-distance profile between colloidal particles. In this paper, we revisit this approach in two ways. First, we describe a new experimental design which allows us to utilize sample volumes as low as a few microliters, involving femtomoles of surface active macromolecules. Secondly, we extensively describe the characterization and preparation of the magnetic colloids, and we give a quantitative evaluation of performance and resolution of the technique in terms of force and interparticle separation.

Electrostatic and electrokinetic contributions to the elastic moduli of a driven membrane.

We discuss the electrostatic contribution to the elastic moduli of a cell or artificial membrane placed in an electrolyte and driven by a DC electric field. The field drives ion currents across the membrane, through specific channels, pumps or natural pores. In steady state, charges accumulate in the Debye layers close to the membrane, modifying the membrane elastic moduli. We first study a model of a membrane of zero thickness, later generalizing this treatment to allow for a finite thickness and finite dielectric constant. Our results clarify and extend the results presented by D. Lacoste, M. Cosentino Lagomarsino, and J.F. Joanny (EPL 77, 18006 (2007)), by providing a physical explanation for a destabilizing term proportional to [see formula in text] in the fluctuation spectrum, which we relate to a nonlinear (E(2)) electrokinetic effect called induced-charge electro-osmosis (ICEO). Recent studies of ICEO have focused on electrodes and polarizable particles, where an applied bulk field is perturbed by capacitive charging of the double layer and drives the flow along the field axis toward surface protrusions; in contrast, we predict "reverse" ICEO flows around driven membranes, due to curvature-induced tangential fields within a nonequilibrium double layer, which hydrodynamically enhance protrusions. We also consider the effect of incorporating the dynamics of a spatially dependent concentration field for the ion channels.

Fluctuation theorem for the flashing ratchet model of molecular motors.

Molecular motors convert chemical energy derived from the hydrolysis of adenosine triphosphate (ATP) into mechanical energy. A well-studied model of a molecular motor is the flashing ratchet model. We show that this model exhibits a fluctuation relation known as the Gallavotti-Cohen symmetry. Our study highlights the fact that the symmetry is present only if the chemical and mechanical degrees of freedom are both included in the description.

Thermal expansion within a chain of magnetic colloidal particles.

We study the thermal expansion of chains formed by self-assembly of magnetic colloidal particles in a magnetic field. Using video microscopy, complete positional data of all the particles of the chains is obtained. By changing the ionic strength of the solution and the applied magnetic field, the interaction potential can be tuned. We analyze the thermal expansion of the chain using a simple model of a one-dimensional anharmonic crystal of finite size.

Stochastic model for nucleosome sliding under an external force.

Heat-induced diffusion of nucleosomes along DNA is an experimentally well-studied phenomenon, presumably induced by twist defects that propagate through the wrapped DNA portion. The diffusion constant depends dramatically on the local mechanical properties of the DNA and the presence of DNA-binding ligands. This has been quantitatively understood by a stochastic three-state model. Future experiments are expected to allow application of forces on the nucleosome that induce a directed sliding. By extending the three-state model, the present work studies theoretically the response of the nucleosome to such external forces and how it is affected by the mechanical properties of the DNA and the presence of DNA-binding ligands.

Fluctuation theorem and large deviation function for a solvable model of a molecular motor.

We study a discrete stochastic model of a molecular motor. This discrete model can be viewed as a minimal ratchet model. We extend our previous work on this model, by further investigating the constraints imposed by the fluctuation theorem on the operation of a molecular motor far from equilibrium. In this work, we show the connections between different formulations of the fluctuation theorem. One formulation concerns the generating function of the currents while another one concerns the corresponding large deviation function, which we have calculated exactly for this model. A third formulation concerns the ratio of the probability of observing a velocity v to the same probability of observing a velocity -v . Finally, we show that all the formulations of the fluctuation theorem can be understood from the notion of entropy production.

Knowledge, behaviors, and attitudes of HIV-infected men about syphilis.

OBJECTIVE: To explore knowledge on syphilis, sexual behaviors, and attitudes in men living with HIV in southwestern France. PATIENTS AND METHODS: In the ANRS CO3 Aquitaine Cohort of people living with HIV (PLHIV), a self-administered questionnaire was proposed to all male PLHIV attending one of the seven participating clinics between September 22 and October 24, 2014. The 15 questions explored patient knowledge about syphilis disease, attitudes, and behaviors during sexual intercourse. RESULTS: Among 302 patients surveyed, 101 reported at least one episode of syphilis. A history of syphilis was associated with awareness that syphilis was on the rise in men who have sex with men (MSM) in the Aquitaine region (46% vs. 22%, P<0.0001). Knowledge that syphilis could be transmitted by oral sex was low in both patients with (37%) and without (20%) a history of syphilis (P=0.0045). Patients with a history of syphilis more often used recreational drugs (RR 1.6; P=0.0028). Among 160 patients who had sexual intercourse with a man in the past 12 months, 23% reported using condoms for oral intercourse and 80% reported using condoms for anal intercourse. Sixty-two per cent of MSM declared being ready to change their practice if informed about the rise in syphilis. CONCLUSIONS: This survey revealed important information gaps in PLHIV about syphilis and related behavior. The reported receptiveness of this population to behavioral change may help inform educational interventions.

[Efficacy and safety of pegylated-interferon plus ribavirin in HIV-infected patients co-infected with hepatitis C virus in clinical practice: a 32 cases observational follow-up]. / Efficacité et tolérance de l'association interféron pégylé-ribavirine chez les patients co-infectés VIH-VHC en pratique clinique: étude observationnelle de 32 patients.

OBJECTIVE: To describe efficacy and safety in clinical practice of pegylated interferon plus ribavirin (INFpeg-Riba) in the treatment of hepatitis C viral infection (HCV) in HIV infected patients. METHODS: Monocentric retrospective study with inclusion of all patients who received at least once INFpeg-Riba before April 1st 2003. All patients were followed up to six months after the end of HCV therapy. RESULTS: Thirty two HIV-positive patients (23 men and 9 women) with chronic hepatitis C treated by INFpeg-Riba were included. The mean age was 43 years. Fourteen patients carried HCV genotype 2 or 3 (43 %) and 18 patients carried genotype 1 or 4 (57%). The Metavir score of fibrosis showed fibrosis F1 (N =3), F2 (N =14), F3 (N =7) and F4 - cirrhosis (N =8). Twenty six patients (81%) were naive for anti hepatitis C drugs. Thirty one per cent of patients were at AIDS stage and 84% were receiving antiretroviral drugs. The mean CD4 cell count was 469 /ml and the plasma RNA HIV was less than 50 copies /ml in 57% of the cases. Adverse events leading to reduction of dose of drugs occurred in 40% and adverse events leading to discontinuation treatment occurred in 12%. A decline of CD4 cell count <200 CD4/ml was observed in 15%. Clearance of HCV-RNA in end of treatment was seen in 46 % and sustained virological response in 34 %. The main predictors of sustained virological response were HCV genotype 2 or 3 (P =0.04) and plasma HIV RNA less than 50 copies/ml (P =0.001). The predictive value of good virological response of a CD4 cell count >350/ml before treatment was very near the statistical significancy (p =0.07). CONCLUSIONS: The efficacy of pegylated interferon plus ribavirin in HIV-HCV co-infected patients is disappointing mainly due to a poor tolerance. In addition to HCV genotype, plasma HIV RNA level and CD4 cell count were essential to predict INFpeg-Riba response and should be taken into account in the process leading to the initiation of such therapy in HIV-HCV co-infected patients.

[Portal vein thrombosis in HIV-infected patients: report of four cases]. / Thrombose portale chez des patients infectés par le virus de l'immunodéficience humaine: à propos de quatre observations.

Portal vein thrombosis (PVT) seems rare among HIV infected patients. Even though, the report of such cases is of great interest because it may help to determine the factors of occurrence. We describe cases of PVT in 4 HIV-infected men, aged 32 - 64. Two of them were co-infected with hepatitis C virus (HCV). The four patients had a history of disseminated mycobacterial infection (one case of tuberculosis, 3 cases of mycobacterium avium complex infection) with abdominal lymphadenitis. Despite HAART, their immunodeficiency was profound (CD4: 65 to 216/mm(3)). At the time of diagnosis, two patients were treated with protease-inhibitor containing regimen: indinavir (one case), ritonavir-saquinavir (one case). PVT was revealed by haematemesis (one case), abdominal pain (ome case), anasarca (2 cases). In three patients, the diagnosis of PVT was confirmed by imagery (echo-doppler or angio- RMI), and for the last patient, PVT was found during the transjugular intrahepatic portosystemic shunt setup. A low level of C protein was diagnosed in one case. Cirrhosis was not found in HIV-HCV co-infected patients. Two patients died early after diagnosis, one patient died 3 years after the onset of symptoms. Various factors may cause the development of a PVT in HIV infected patient. Serious immunodeficiency, opportunistic infections such as tuberculosis and mycobacterium avium complex related infection with abdominal lymphadenitis can further the development of PVT. Protease-inhibitor might have facilitated the process. Due to the severe prognosis of advanced cases, early evocation of diagnosis is needed.

A cohort study of 89 HIV-1-infected adult patients contaminated by blood products: Bordeaux 1981-1989. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine (GECSA)

A hospital-based surveillance of HIV infection was implemented in the Bordeaux Regional University Hospital (France). This reporting system, initiated by the Groupe d'Epidemiologie Clinique du SIDA en Aquitaine, identified and followed-up 89 adult patients with transfusion-associated HIV-1 infection (7.2% of all reported cases). Contamination occurred between August 1981 and June 1985 and diagnosis was made between 1985 and 1989. By 30 June 1990, 43 patients (48.3%) had full-blown AIDS, and 28 of them had died. The mean follow-up period was 66 months (s.d. 16 months). The mean incubation period, i.e. The time interval between the contaminating transfusion and the development of full-blown AIDS, was 62 months [median 73 months; 95% confidence interval (CI) 66-82 months]. Five years after contamination, the cumulative probability of reaching the AIDS stage was 34.2% (95% CI 20.3-49.3%), and the probability of survival was 81.7% (95% CI 72.5-90.0%). From this surveillance system we estimate that in south-western France at the end of 1989 the cumulative incidence of transfusion-associated HIV-1 infection was at least 126 cases (45.6 per million inhabitants). Although we anticipate an increase in transfusion-associated AIDS cases over the next 5 years, there have been no reports of contamination after 1 August 1985, when systematic screening of HIV antibodies was implemented in French blood banks. This confirms the efficacy of screening in countries like France where the risk of contamination through blood products is now minimal.

Women and HIV infection: a cohort study of 483 HIV-infected women in Bordeaux, France, 1985-1991. The Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.

OBJECTIVES: To study the epidemiological trends, clinical patterns, evolution and prognosis of HIV infection in women. DESIGN: Cohort study of 1816 HIV-infected patients. RESULTS: Up to 1 January 1991, 483 (26.6%) of the patients reported to the Groupe d'Epidemiologie Clinique du SIDA en Aquitaine surveillance system were women. The male-to-female ratio has decreased progressively (3.4:1 in 1985; 2.7:1 in 1990) over time. Fifty per cent of HIV-infected women are or have been intravenous drug users (IVDU). The proportion of heterosexually acquired HIV infection increased from 11.6 to 34.6% over the last 5 years; 46.9% of the women infected through heterosexual intercourse reported sexual contacts with male IVDU. Excluding Kaposi's sarcoma, no significant difference was observed between men and women in the overall distribution of AIDS-defining events. The observed trend of a slower progression to AIDS in women, compared with men, disappeared when controlling for prognostic variables. However, female sex significantly enhanced survival after AIDS diagnosis in multivariate analysis (relative risk, 2.7; 95% confidence interval, 1.1-6.2). CONCLUSION: Early diagnosis of HIV infection in female patients and prevention of HIV infection among women is now a priority for public health interventions, both in industrialized and in developing countries.

Changes in CD4+ cell count and the risk of opportunistic infection or death after highly active antiretroviral treatment. Groupe d'Epidémiologie Clinique du SIDA en Aquitaine.

OBJECTIVE: To study the relationship between the CD4+ cell response after initiation of protease inhibitors and the occurrence of opportunistic infections and survival. DESIGN: Prospective observational cohort study. METHODS: HIV-1-seropositive subjects followed-up in HIV centres of Bordeaux University Hospital, Southwest France who were prescribed at least one available protease inhibitor between January and December 1996 were included in this analysis. A Cox model estimated the independent effect of baseline covariates and CD4+ cell response, considered as a time-dependent covariate, on the occurrence of new AIDS-defining opportunistic infection, new AIDS-defining events, new AIDS-defining opportunistic infection or death. RESULTS: A total of 556 HIV-positive patients were prescribed at least one protease inhibitor: 34% saquinavir, 52% indinavir, and 14% ritonavir. Median CD4+ cell count at baseline was 95 x 10(6)/l and mean plasma HIV RNA was 5.0 log10 copies/ml. After a median follow-up of 230 days, 65 patients experienced a new episode of opportunistic infection, 79 patients experienced at least one AIDS-defining event, and 24 had died. On average, the increase in CD4+ cell count was 42 x 10(6)/l (SD, 74) after a median of 49 days. In the multivariate analysis of opportunistic infection or death, each 50% higher CD4+ cell count at baseline was associated with a 23% reduction [95% confidence interval (CI), 14-30] of risk. Each 50% increase in CD4+ cell count during follow-up was associated with a 9% reduction (95% CI, 2-15) of risk, adjusted for the presence of AIDS prior to protease inhibitor therapy (hazard ratio, 3.76 versus absence of AIDS; P < 0.01) and haemoglobin level (hazard ratio, 0.48 if > 11 g/dl versus <11 g/dl; P < 0.01). CONCLUSION: Our results show, at least indirectly, how protease inhibitors might produce clinical stabilization. This result may be due to improved functionality of CD4+ cells in patients started on protease inhibitors.

A cohort study of nevirapine tolerance in clinical practice: French Aquitaine Cohort, 1997-1999.

We performed a retrospective study to evaluate, under routine circumstances, the tolerance and immunovirological changes associated with antiretroviral regimens that contain nevirapine in 137 patients (88% were antiretroviral experienced). During a mean follow-up of 11 months, 33% of patients reported side effects attributed to nevirapine, and 21% discontinued treatment because of poor tolerance. Administration of antihistamines or corticosteroids at the initiation of treatment was not protective against adverse events (relative risk, 0.82; 95% confidence interval, 0.49-1.38). The proportion of patients with hepatitis C virus (HCV) and/or hepatitis B virus (HBV) coinfection who had alanine aminotransferase levels of >100 IU/L increased from 19.4% at baseline to 42.9% at month 12 of follow-up (P=.02). We noticed a significant increase of the proportion of patients with total cholesterol levels of >5.5 mM (P=.02). We have shown that there is a high level of discontinuation of nevirapine therapy in clinical practice and that side effects were not prevented by administration of antihistamines or corticosteroids. Coinfection with HCV or HBV increased the risk of hepatotoxicity, which lead to the cautious use of nevirapine for such patients.

Model of the distribution and metabolism of the gonadotropin-releasing hormone (GnRH) agonist [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide in man.

The kinetics of plasma immunoreactive [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide, a potent GnRH agonist, was assessed in nine normal adult men over a period of 24 h after a rapid sc injection of 1 or 10 micrograms peptide/kg BW. The specific RIA of the GnRH agonist is characterized by a minimum detectable dose of 5.0 +/- 0.5 pg peptide, while the midrange effective dose is 73 +/- 8 pg. The within- and between-assay coefficients of variation range from 2-7% and from 10-15%, respectively. When the volume of the central compartment is set proportional to the logarithm of the plasma concentration of the GnRH agonist, the time courses of both doses are statistically well represented by a two-compartment model to which a source compartment is added to represent the sc route of administration. The sc diffusion to plasma is 5 times faster than any other fractional transport rate of the model (5%/min). Disposal occurs at a maximum rate of 0.55%/min from the central compartment, which includes plasma, and 0.25%/min from the peripheral compartment. As simulated with the model, 90% of the steady state is reached 13 h and 45 min after the onset of a sc continuous infusion. A molecule spends, on the average, from 6 h to 9 h and 45 min in the whole organism; 30-50% of this period is accounted for by residence in the central compartment. The volume of the central compartment reaches 208 mL/kg BW, and the MCR is estimated at 1.18 mL/min.kg BW for a steady state of 1 ng/mL plasma. The plasma dynamics of [D-Trp6,Des-Gly-NH2(10)]GnRH ethylamide in men are at least 10 times slower than those reported for the natural GnRH, thus indicating the relevance of its clinical use in suppressive therapy of LH secretion.

Increase in CD3+ CD4- T lymphocytes in patients with AIDS and disseminated Mycobacterium avium-intracellulare complex infection: a prospective study. GECSA. Groupe d'Epidemiologie Clinique du SIDA en Aquitaine.

In a retrospective study, an increase in double-negative (CD3+ CD4- CD8-) (DN) T lymphocytes has been shown to be an independent predictor of disseminated Mycobacterium avium complex (D.MAC) infection in patients with less than 100 CD4+ T cells per mm3. To better characterize this cell expansion, a prospective study was designed. From July 1995 to April 1997, 206 HIV-infected patients with less than 100 CD4+ T cells per mm3 were prospectively followed up and immunophenotyped. The median followup was 1.1 year (+/-0.5 year), and 14 new D.MAC infections were diagnosed among 84 first AIDS-defining events. In univariate and multivariate analyses, D.MAC infections were the only opportunistic infection with a significant increase in DN T-cell percentage (median = 6.6; range = 1.7 to 24.5, P = 0.004) compared with patients without any opportunistic infection. This alteration in T-lymphocyte count could constitute a predictor for D.MAC infection in clinical practice.

Effect of 2-week combination therapy with the luteinizing hormone-releasing hormone (LHRH) agonist [D-Trp6, des-Gly-NH2(10)]LHRH ethylamide and the antiandrogen flutamide on prostate structure and steroid levels in the dog.

Treatment of adult dogs for 15 days with the luteinizing hormone-releasing hormone (LHRH) agonist [D-Trp6, des-Gly-NH2(10)]LHRH ethylamide (50 micrograms daily, s.c.) causes a 41.6% inhibition of prostatic weight while a 55% inhibition is achieved when the antiandrogen flutamide (250 mg, twice daily) is given in association with the LHRH agonist (p less than 0.01). At histology, the glandular acini in the prostate of animals treated with the combination therapy are more atrophied than with either treatment used alone. A 2-week treatment with the LHRH agonist is characterized by two distinct phases, namely a stimulation of testicular androgen secretion between days 0 and 8 followed by an inhibition between days 9 and 15. During the inhibitory phase, the concentration of all testicular steroids progressively decreased to castration levels, thus indicating that the differences observed at the prostatic level at 2 weeks are due to the inhibition of androgen action by the antiandrogen flutamide during the period which precedes complete chemical castration by the LHRH agonist. Flutamide administered alone had no effect on plasma or prostatic steroid levels measured after 2 weeks and it did not interfere with the potent and generalized inhibitory effect of the LHRH agonist on the serum and prostatic concentration of all steroids measured.(ABSTRACT TRUNCATED AT 250 WORDS)