Effect of cascade overlap and C15 clusters on the damage evolution in Fe : An OKMC study

In order to investigate the long-term evolution of radiation-induced defects in the fission- and fusion-relevant material iron, we introduce cascade overlap effects into Object Kinetic Monte Carlo simulations. In addition to cascade overlap, we study the effect of introducing discrete C15 Laves phase clusters into the simulations. By applying either, none, or both of these effects we identify how they influence the evolution of the system. We find that both cascade overlap and C15 clusters affect the evolution of the radiation damage in different ways and on different time scales. Cascade overlap is found to reduce the number of Frenkel pairs. On the other hand, the explicit consideration of C15 Laves phase clusters increases the accumulation of defects at low dose. The results are compared to Molecular Dynamics simulation results under similar conditions.Peer reviewe

Characterisation of Glasgow/CNM Double-Sided 3D Sensors.

3D detectors are proposed as an alternative to planar silicon technology to withstand the high radiation environments in planned future high energy physics experiments. Here we review the characterization of double-sided 3D detectors designed and built at CNM and the University of Glasgow. A non-irradiated sensor is characterized in a pion test-beamutilizing the Timepix telescope. The charge collection and detection efficiency across the unit pixel are shown. Area of inefficiency can be found at the columnar electrodes at perpendicular angles of beam incidence while the pixels are shown to be fully efficient at angles greater than ten degrees. A reduction in charge sharing compared to the planar technology is also demonstrated. Charge collection studies on irradiated devices with a Sr-90 source show higher charge collection efficiency for 3D over planar sensors at significantly lower applied bias. The sub-pixel response is probed by a micro-focused laser beam demonstrating areas of charge multiplication at high bias voltages

Morphology of supported polymer electrolyte ultra-thin films: a numerical study

Morphology of polymer electrolytes membranes (PEM), e.g., Nafion, inside PEM fuel cell catalyst layers has significant impact on the electrochemical activity and transport phenomena that determine cell performance. In those regions, Nafion can be found as an ultra-thin film, coating the catalyst and the catalyst support surfaces. The impact of the hydrophilic/hydrophobic character of these surfaces on the structural formation of the films has not been sufficiently explored yet. Here, we report about Molecular Dynamics simulation investigation of the substrate effects on the ionomer ultra-thin film morphology at different hydration levels. We use a mean-field-like model we introduced in previous publications for the interaction of the hydrated Nafion ionomer with a substrate, characterized by a tunable degree of hydrophilicity. We show that the affinity of the substrate with water plays a crucial role in the molecular rearrangement of the ionomer film, resulting in completely different morphologies. Detailed structural description in different regions of the film shows evidences of strongly heterogeneous behavior. A qualitative discussion of the implications of our observations on the PEMFC catalyst layer performance is finally proposed

The history of degenerate (bipartite) extremal graph problems

This paper is a survey on Extremal Graph Theory, primarily focusing on the case when one of the excluded graphs is bipartite. On one hand we give an introduction to this field and also describe many important results, methods, problems, and constructions.Comment: 97 pages, 11 figures, many problems. This is the preliminary version of our survey presented in Erdos 100. In this version 2 only a citation was complete

Acceptability of Male Circumcision for the Prevention of HIV/AIDS in the Dominican Republic

Male circumcision (MC) is an effective strategy to prevent HIV infection in heterosexual men. To our knowledge, there are no studies of the acceptability of this procedure in the Dominican Republic (DR). The main objective of this study was to assess the acceptability of MC to prevent HIV transmission among men ages 18 to 50 years in the Altagracia Province in the Dominican Republic. Because differences in culture and beliefs between Haitians and Dominicans could potentially influence their acceptability of MC, we conducted a comparative analysis based on national origin.A survey was administered to a convenience sample of 368 men. The questionnaire was divided in 3 sections: 1) Background demographics (including national origin), 2) Male circumcision and 3) Sexual health. Stratified and logistic multivariate regression analyses were performed to identify factors associated with the acceptability of MC.The sample consisted of 238 (65%) Dominicans and 130 (35%) Haitian immigrants. Almost all participants were uncircumcised (95%) and about half (52%) were single. The overall acceptability of MC was 29%. The number of men willing to be circumcised increased to 67% after an information session explaining the benefits of the procedure. 74% of men reported that they would be willing to circumcise their sons after hearing that information. In multivariate analysis, Haitian nationality (OR=1.86, 95% CI 1.01-3.41), knowing that circumcision improves hygiene (OR=2.78, 95% CI 1.29-6.0) and not believing that circumcision decreases sexual pleasure (OR=2.18, 95% CI 1.20-3.94) were associated with a higher acceptability of the procedure. Although age was not significantly associated with the willingness to be circumcised in the multivariate analysis, stratified analysis based on national origin suggested that younger Dominicans (<30 years of age) are more likely to accept the procedure when compared to their older counterparts (OR=2.17, 95% CI 1.14-4.12).An important number of sexually active men in the DR may be willing to be circumcised if educational resources detailing the benefits of the procedure are made available. These educational activities would constitute a great opportunity to teach about sexual health and reinforce safe sex practices

The Side Population in Human Lung Cancer Cell Line NCI-H460 Is Enriched in Stem-Like Cancer Cells

Lung cancer is among the most lethal malignancies with a high metastasis and recurrence rate. Recent studies indicate that tumors contain a subset of stem-like cancer cells that possess certain stem cell properties. Herein, we used Hoechst 33342 dye efflux assay and flow cytometry to isolate and characterize the side population (SP) cells from human lung cancer cell line NCI-H460 (H460). We show that the H460 SP cells harbor stem-like cells as they can readily form anchorage-independent floating spheres, possess great proliferative potential, and exhibit enhanced tumorigenicity. Importantly, the H460 SP cells were able to self-renew both in vitro and in vivo. Finally, we show that the H460 SP cells preferentially express ABCG2 as well as SMO, a critical mediator of the Hedgehog (HH) signaling, which seems to play an important role in H460 lung cancer cells as its blockage using Cyclopamine greatly inhibits cell-cycle progression. Collectively, our results lend further support to the existence of lung cancer stem cells and also implicate HH signaling in regulating large-cell lung cancer (stem) cells

Thermodynamics and dynamics of the formation of spherical lipidic vesicles

We propose a free energy expression accounting for the formation of spherical vesicles from planar lipidic membranes and derive a Fokker-Planck equation for the probability distribution describing the dynamics of vesicle formation. We found that formation may occur as an activated process for small membranes and as a transport process for sufficiently large membranes. We give explicit expressions for the transition rates and the characteristic time of vesicle formation in terms of the relevant physical parameters.Comment: 14pgs, 6 figures, sendo to Jour. Phys. Bio

Chlorhexidine Substantivity on Salivary Flora and Plaque-Like Biofilm: An In Situ Model

This work was supported by project FIS PI11/01383 from Carlos III Institute of Health (Ministry of Economy and Competitiveness, Madrid, Spain