Formation of rings in galactic discs by infalling small companions

We use N-body simulations to study the formation of rings in a disc galaxy by the impact of a small spherical companion. Both barred and nonbarred target discs are considered. We discuss the effect of the properties of the target disc (distribution of mass in the disc, velocity dispersion, etc.) as well as of the mass and orbit of the companion on the properties of the rings, such as their amplitude, width, shape, expansion velocity and lifetime. In particular the amplitude, width, lifetime and expansion velocity of the first ring increase considerably with companion mass, and so does the expansion velocity of the particles in it and the total extent of the disc after the interaction. We also discuss the formation and evolution of spokes and show that they can be caused by companions of relatively small mass. In our three examples of oblique impacts on barred target galaxies we note important transient displacements of the bar, as well as changes of its pattern speed and size. An asymmetric pseudoring is formed in each case, and during the first stages of its evolution the bar forms part of it.Comment: 21 pages Latex, 22 figures, of which 7 as separate gif-files. Requires mn.sty, accepted for publication in MNRAS. High resolution version at http://www-obs.cnrs-mrs.fr/dynamique/pap/ring.htm

Influence of interfaces reflectivity for central thickness measurement of a contact lens by low coherence interferometry

This paper evaluates quantitatively the relative interfaces reflectivity of a soft contact lens set in air or in water by a low coherence interferometric method. The sensitivity of the set-up is then measured and the minimum reflectivity is estimated to be as low as 0.02%. Measurement of the central thickness of the lens, even when it is immersed in water, is then possible using a new supercontinuum source

P19-26. Directing macaque immune responses with an anti-dendritic cell HIV Gag p24 fusion protein vaccine

International audiencen.

Effects of hydroxyapatite and PDGF concentrations on osteoblast growth in a nanohydroxyapatite-polylactic acid composite for guided tissue regeneration

The technique of guided tissue regeneration (GTR) has evolved over recent years in an attempt to achieve periodontal tissue regeneration by the use of a barrier membrane. However, there are significant limitations in the currently available membranes and overall outcomes may be limited. A degradable composite material was investigated as a potential GTR membrane material. Polylactic acid (PLA) and nanohydroxyapatite (nHA) composite was analysed, its bioactive potential and suitability as a carrier system for growth factors were assessed. The effect of nHA concentrations and the addition of platelet derived growth factor (PDGF) on osteoblast proliferation and differentiation was investigated. The bioactivity was dependent on the nHA concentration in the films, with more apatite deposited on films containing higher nHA content. Osteoblasts proliferated well on samples containing low nHA content and differentiated on films with higher nHA content. The composite films were able to deliver PDGF and cell proliferation increased on samples that were pre absorbed with the growth factor. nHA–PLA composite films are able to deliver active PDGF. In addition the bioactivity and cell differentiation was higher on films containing more nHA. The use of a nHA–PLA composite material containing a high concentration of nHA may be a useful material for GTR membrane as it will not only act as a barrier, but may also be able to enhance bone regeneration by delivery of biologically active molecules

Training less-experienced faculty improves reliability of skills assessment in cardiac surgery

OBJECTIVE: Previous work has demonstrated high inter-rater reliability in the objective assessment of simulated anastomoses among experienced educators. We evaluated the inter-rater reliability of less-experienced educators and the impact of focused training with a video-embedded coronary anastomosis assessment tool. METHODS: Nine less-experienced cardiothoracic surgery faculty members from different institutions evaluated 2 videos of simulated coronary anastomoses (1 by a medical student and 1 by a resident) at the Thoracic Surgery Directors Association Boot Camp. They then underwent a 30-minute training session using an assessment tool with embedded videos to anchor rating scores for 10 components of coronary artery anastomosis. Afterward, they evaluated 2 videos of a different student and resident performing the task. Components were scored on a 1 to 5 Likert scale, yielding an average composite score. Inter-rater reliabilities of component and composite scores were assessed using intraclass correlation coefficients (ICCs) and overall pass/fail ratings with kappa. RESULTS: All components of the assessment tool exhibited improvement in reliability, with 4 (bite, needle holder use, needle angles, and hand mechanics) improving the most from poor (ICC range, 0.09-0.48) to strong (ICC range, 0.80-0.90) agreement. After training, inter-rater reliabilities for composite scores improved from moderate (ICC, 0.76) to strong (ICC, 0.90) agreement, and for overall pass/fail ratings, from poor (kappa = 0.20) to moderate (kappa = 0.78) agreement. CONCLUSIONS: Focused, video-based anchor training facilitates greater inter-rater reliability in the objective assessment of simulated coronary anastomoses. Among raters with less teaching experience, such training may be needed before objective evaluation of technical skills

Dynamic Interferometry Lithography on a TiO 2

International audienceSolar electricity is one of the most promising renewable energy resources. However, the ratio module's cost/energy produced remains a major issue for classical photovoltaic energy. Many technologies have been developed to solve this problem, by using micro-or nanostructuring on the solar cell or on the module. These kinds of structuring are often used as antireflection and light-trapping tools. In the meantime, other solar technologies are considered, such as concentration photovoltaic modules. This article presents a module combining both approaches, that is, nanostructures and concentration, in order to increase the module's profitability. Sol-gel derived TiO 2 diffraction gratings, made by dynamic interferometric lithography, are added on the top of the glass cover to deflect unused light onto the solar cell, increasing the module efficiency

H-reflex amplitude asymmetry is an earlier sign of nerve root involvement than latency in patients with S1 radiculopathy

Abstract Background Based on our clinical experience, the H-reflex amplitude asymmetry might be an earlier sign of nerve root involvement than latency in patients with S1 radiculopathy. However, no data to support this assumption are available. The purpose of this study was to review and report the electrophysiological changes in H-reflex amplitude and latency in patients with radiculopathy in order to determine if there is any evidence to support the assumption that H-reflex amplitude is an earlier sign of nerve root involvement than latency. Results Patients with radiculopathy showed significant amplitude asymmetry when compared with healthy controls. However, latency was not always significantly different between patients and healthy controls. These findings suggest nerve root axonal compromise that reduced reflex amplitude earlier than the latency parameter (demyelination) during the pathologic processes. Conclusion Contrary to current clinical thought, H-reflex amplitude asymmetry is an earlier sign/parameter of nerve root involvement in patients with radiculopathy compared with latency.</p