Scattering of dislocated wavefronts by vertical vorticity and the Aharonov-Bohm effect II: Dispersive waves

Previous results on the scattering of surface waves by vertical vorticity on shallow water are generalized to the case of dispersive water waves. Dispersion effects are treated perturbatively around the shallow water limit, to first order in the ratio of depth to wavelength. The dislocation of the incident wavefront, analogous to the Aharonov-Bohm effect, is still observed. At short wavelengths the scattering is qualitatively similar to the nondispersive case. At moderate wavelengths, however, there are two markedly different scattering regimes according to wether the capillary length is smaller or larger than $\sqrt{3}$ times depth. The dislocation is characterized by a parameter that depends both on phase and group velocity. The validity range of the calculation is the same as in the shallow water case: wavelengths small compared to vortex radius, and low Mach number. The implications of these limitations are carefully considered.Comment: 30 pages, 11 figure

OpenAlea 2.0: Architecture of an integrated modeling environment on the web

International audiencePlant modeling is based on the use of a diverse set of design paradigms (L-systems, visual programming, imperative languages or sketch-based interfaces). In this poster, the architecture of a new multi-paradigm and integrated modeling environment is presented. This desktop application will become a distributed web application, allowing to run simulations on a cloud computing system and share virtual experiments on the web. The modeling environment will run on a web browser using HTML5 and WebGL technologies

Single File Diffusion of particles with long ranged interactions: damping and finite size effects

We study the Single File Diffusion (SFD) of a cyclic chain of particles that cannot cross each other, in a thermal bath, with long ranged interactions, and arbitrary damping. We present simulations that exhibit new behaviors specifically associated to systems of small number of particles and to small damping. In order to understand those results, we present an original analysis based on the decomposition of the particles motion in the normal modes of the chain. Our model explains all dynamic regimes observed in our simulations, and provides convincing estimates of the crossover times between those regimes.Comment: 30 pages, 9 figure

Two-Phase Flow Simulations for PTS Investigation by Means of Neptune_CFD Code

Two-dimensional axisymmetric simulations of pressurized thermal shock (PTS) phenomena through Neptune_CFD module are presented aiming at two-phase models validation against experimental data. Because of PTS complexity, only some thermal-hydraulic aspects were considered. Two different flow configurations were studied, occurring when emergency core cooling (ECC) water is injected in an uncovered cold leg of a pressurized water reactor (PWR)—a plunging water jet entering a free surface, and a stratified steam-water flow. Some standard and new implemented models were tested: modified turbulent - models with turbulence production induced by interfacial friction, models for the drag coefficient, and interfacial heat transfer models. Quite good agreement with experimental data was achieved with best performing models for both test cases, even if a further improvement in phase change modelling would be suitable for nuclear technology applications

On the bounded cohomology of Lie groups

We show that each integral Borel cohomology class of a connected Lie group G can be represented by a Borel bounded cocycle if and only if the radical of G is linear. This leads to a generalization of Gromov's boundedness theorem on characteristic classes of flat bundles.Comment: 46 pages, new version with added reference

Double-walled carbon nanotubes trigger IL-1β release in human monocytes through Nlrp3 inflammasome activation

Because of their outstanding physical properties, carbon nanotubes (CNTs) are promising new materials in the field of nanotechnology. It is therefore imperative to assess their adverse effects on human health. Monocytes/macrophages that recognize and eliminate the inert particles constitute the main target of CNTs. In this article, we report our finding that double-walled CNTs (DWCNTs) synergize with Tolllike receptor agonists to enhance IL-1β release in human monocytes. We show that DWCNTs–induced IL-1β secretion is exclusively linked to caspase-1 and to Nlrp3 inflammasome activation in human monocytes. We also establish that this activation requires DWCNTs phagocytosis and potassium efflux, but not reactive oxygen specied (ROS) generation. Moreover, inhibition of lysosomal acidification or cathepsin-B activation reduces DWCNT-induced IL-1β secretion, suggesting that Nlrp3 inflammasome activation occurs via lysosomal destabilization. Thus, DWCNTs present a health hazard due to their capacity to activate Nlrp3 inflammasome, recalling the inflammation caused by asbestos and hence demonstrating that they should be used with caution. From the Clinical Editor: This is a very important biosafety/toxicity study regarding double walled carbon nanotubes. The investigators demonstrate that such nanotubes do represent a health hazard due to their capacity to activate Nlrp3 inflammasome, resembling the inflammation caused by asbestos. While further study of this phenomenon is definitely needed, the above findings clearly suggest that special precautions need to be taken when applying these nanoparticles in human disease research

Evolutionary demographic models reveal the strength of purifying selection on susceptibility alleles to late-onset diseases

Assessing the role played by purifying selection on a Susceptibility Allele to Late-Onset Disease (SALOD) is crucial to understand the puzzling allelic spectrum of a disease: most alleles are recent and rare. This fact is surprising, as it suggests that alleles are under purifying selection, while alleles that are involved in post-menopause mortality are often considered neutral in the genetic literature. The aim of this presentation is to use an evolutionary demography model in order to asse..

Measurements and determinants of children's exposure to background gamma radiation in Switzerland.

Epidemiological studies of children's cancer risks associated with background gamma radiation exposure have used geographic exposure models to estimate exposure at their locations of residence. We measured personal exposure to background gamma radiation, and we investigated the extent to which it was associated with children's whereabouts. We collected data on whereabouts and exposure to background gamma radiation over a 5-day period among children aged 4-15 years in Switzerland. We used D-Shuttle dosimeters to measure children's exposure, and we asked parents to write their children's activities in diaries. We used Poisson mixed-effects and linear regression models to investigate the association of hourly and overall doses, respectively, with children's reported whereabouts. During the observed time, 149 participating children spent 66% indoors at home; 19% indoors away from home; and 15% outdoors. The mean personal exposure was 85.7 nSv/h (range 52.3 nSv/h-145 nSv/h). Exposure was 1.077 (95% CI 1.067, 1.087) times higher indoors than outdoors and varied by building material and (predicted) outdoor dose rates. Our study provides detailed information about children's patterns of exposure to background gamma radiation in Switzerland. Dwelling building materials and outdoor dose rates are important determinants of children's exposure. Future epidemiological studies may benefit from including information about building materials

A Wearable Sensor Network for Gait Analysis: A 6-Day Experiment of Running Through the Desert

International audienceThis paper presents a new system for analysis of walking and running gaits. The system is based on a network of wireless nodes with various types of embedded sensors. It has been designed to allow long-term recording in outdoor environments and was tested during the 2010 "Sultan Marathon des Sables" desert race. A runner was fitted with the sensory network for six days of the competition. Although technical problems have limited the amount of data recorded, the experiment was nevertheless suc- cessful: the system did not interfere with the runner, who finished with a high ranking, the concept was validated and high quality data were ac- quired. It should be noted that the loss of some of the measurements was mainly due to problems with the cable connectors between the nodes and batteries. In this paper, we describe the technical aspects of the system developed, the experimental conditions under which it was validated, and give examples of the data obtained with some preliminary processing