Understanding SDBD Actuators: An Experimental Study on Plasma Characteristics

The working mechanisms of surface dielectric barrier discharge (SDBD) plasma actuators foreseen as aerodynamic control devices is investigated experimentally on a common platform, referred to as the NATO-AVT-RTO-190 test case. A better understanding of the working principle and characteristics of SDBD paves the way for more efficient and safe use of plasma actuators in aerodynamic applications. In this study, a characterisation of the plasma is done by current measurements, fast-camera plasma imaging and force measurements. Furthermore, more advanced plasma characteristics such as reduced electric field and excited species population are found by Optical Emission Spectroscopy. The collective goal of this research is to contribute to a database which can also be used for numerical verification and validation by varying the key parameters such as frequency and voltage

6-hydroxydopamine-mediated release of norepinephrine increases faecal excretion of Salmonella enterica serovar Typhimurium in pigs

Salmonella enterica serovar Typhimurium is an animal and zoonotic pathogen of worldwide importance. In pigs, transport and social stress are associated with reactivation and spread of Salmonella Typhimurium infection. The stress-related catecholamine norepinephrine (NE) has been reported to activate growth and virulence factor expression in Salmonella; however the extent to which NE contributes to stress-associated salmonellosis is unclear. We studied the impact of releasing NE from endogenous stores during Salmonella Typhimurium infection of pigs by administration of 6-hydroxydopamine (6-OHDA), which selectively destroys noradrenergic nerve terminals. Treatment of pigs with 6-OHDA 7 or 16 days post-oral inoculation with Salmonella Typhimurium produced elevated plasma NE levels and transiently, but significantly, increased faecal excretion of the challenge strain. Oral administration of NE to Salmonella Typhimurium-infected pigs also transiently and significantly increased shedding; however pre-culture of the bacteria with NE did not alter the outcome of infection. Salmonella has been proposed to sense and respond to NE via a homologue of the adrenergic sensor kinase QseC. A ΔqseC mutant of Salmonella Typhimurium was consistently excreted in lower numbers than the parent strain post-oral inoculation of pigs, though not significantly so. 6-OHDA treatment of pigs infected with the ΔqseC mutant also increased faecal excretion of the mutant strain, albeit to a lesser extent than observed upon 6-OHDA treatment of pigs infected with the parent strain. Our data support the notion that stress-related catecholamines modulate the interaction of enteric bacterial pathogens with their hosts

Online clinical reasoning assessment with the Script Concordance test: a feasibility study

BACKGROUND: The script concordance (SC) test is an assessment tool that measures capacity to solve ill-defined problems, that is, reasoning in context of uncertainty. This tool has been used up to now mainly in medicine. The purpose of this pilot study is to assess the feasibility of the test delivered on the Web to French urologists. METHODS: The principle of SC test construction and the development of the Web site are described. A secure Web site was created with two sequential modules: (a) The first one for the reference panel (n = 26) with two sub-tasks: to validate the content of the test and to elaborate the scoring system; (b) The second for candidates with different levels of experience in Urology: Board certified urologists, residents, medical students (5 or 6(th )year). Minimum expected number of participants is 150 for urologists, 100 for residents and 50 for medical students. Each candidate is provided with an individual access code to this Web site. He/she may complete the Script Concordance test several times during his/her curriculum. RESULTS: The Web site has been operational since April 2004. The reference panel validated the test in June of the same year during the annual seminar of the French Society of Urology. The Web site is available for the candidates since September 2004. In six months, 80% of the target figure for the urologists, 68% of the target figure for the residents and 20% of the target figure for the student passed the test online. During these six months, no technical problem was encountered. CONCLUSION: The feasibility of the web-based SC test is successful as two-thirds of the expected number of participants was included within six months. Psychometric properties (validity, reliability) of the test will be evaluated on a large scale (N = 300). If positive, educational impact of this assessment tool will be useful to help urologists during their curriculum for the acquisition of clinical reasoning skills, which is crucial for professional competence

On line clinical reasoning assessment with Script Concordance test in urology: results of a French pilot study

BACKGROUND: The Script Concordance test (SC) test is an assessment tool that measures the capacity to solve ill-defined problems, that is, reasoning in a context of uncertainty. This study assesses the feasibility, reliability and validity of the SC test made available on the Web to French urologists. METHODS: A 97 items SC test was developed based on major educational objectives of French urology training programmes. A secure Web site was created with two sequential modules: a) The first one for the reference panel to elaborate the scoring system; b) The second for candidates with different levels of experience in urology: Board certified urologists, chief-residents, residents, medical students. All participants were recruited on a voluntary basis. Statistical analysis included descriptive statistics of the participants' scores and factorial analysis of variance (ANOVA) to study differences between groups' means. Reliability was evaluated with Cronbach's alpha coefficient. RESULTS: The on line SC test has been operational since June 2004. Twenty-six faculty members constituted the reference panel. During the following 10 months, 207 participants took the test online (124 urologists, 29 chief-residents, 38 residents, 16 students). No technical problem was encountered. Forty-five percent of the participants completed the test partially only. Differences between the means scores for the 4 groups were statistically significant (P = 0.0123). The Bonferroni post-hoc correction indicated that significant differences were present between students and chief-residents, between students and urologists. There were no differences between chief-residents and urologists. Reliability coefficient was 0.734 for the total group of participants. CONCLUSION: Feasibility of Web-based SC test was proved successful by the large number of participants who participated in a few months. This Web site has permitted to quickly confirm reliability of the SC test and develop strategy to improve construct validity of the test when applied in the field of urology. Nevertheless, optimisation of the SC test content, with a smaller number of items will be necessary. Virtual medical education initiative such as this SC test delivered on the Internet warrants consideration in the current context of national pre-residency certification examination in France

C005 Serotoninergic 5-HT2B receptor blockade prevents superoxide anion mediated cardiac hypertrophy induced by angiotensin II

ObjectiveTo study the role of the serotoninergic 5-HT2B receptor in the development of cardiac hypertrophy and its link with left ventricular superoxide anion generation in a mouse model of angiotensin II-induced hypertension.MethodsWild-type and 5-HT2B receptor knock-out (KO) mice were perfused with angiotensin II (0.2mg.kg-1.d-1) for 14 days with or without SB215505 (1mg.kg-1.d-1), an antagonist of the 5-HT2B receptor. Heart rate and blood pressure were measured by tail-cuff plethysmography. Cardiac hypertrophy was evaluated by echocardiography and direct measurement of heart weight. Superoxide anion production and maximal NAD(P)H oxidase activity were measured by a chemiluminescence method using lucigenin. Superoxide anion production was also measured in primary left ventricular fibroblasts cell cultures.ResultsAngiotensin II increased superoxide anion production (+32 %), the maximal activity of NAD(P)H oxidase (+84 %) in left ventricle of wild-type mice concomitantly with the arterial blood pressure (+37mmHg) and the heart/body weight ratio (+17 %). A pharmacological blockade (SB215505) or a genetic suppression of the 5-HT2B receptor prevented the increased superoxide anion production and cardiac hypertrophy but had no effect on cardiac hemodynamics or blood pressure. Angiotensin II also increased NAD(P)H oxidase activity in cultured cardiac fibroblasts and this increase was prevented by SB215505.ConclusionThe 5-HT2B receptor is a new potential target for the prevention of cardiac hypertrophy and its associated superoxide anion production. Cells of the extracellular matrix could possibly be involved in this mechanism