Astrophysical Production of Microscopic Black Holes in a Low Planck-scale World

In the framework of brane-world models lowering the Planck scale to the TeV range, it has recently been pointed out that small black holes could be formed at particle colliders or by neutrinos interactions in the atmosphere. This article aims at reviewing other places and epochs where microscopic black holes could be formed : the interstellar medium and the early Universe. The related decay channels and the propagation of the emitted particles are studied to conclude that, in spite of the large creation rate for such black holes, the amount of produced particles do not conflict with experimental data. This shows, from the astronomical viewpoint, that models with large extra dimensions making the gravity scale much lower are compatible with observations.Comment: To appear in Ap

Microspherical laser in Erbium-Ytterbium-doped glass

session A « Micro laser sources » [A3]International audienceWe present experimental results on a Er3+/Yb3+ doped microspherical laser. Our experiments have been focused on the 4I13/2 → 4I15/2 transition at 1550 nm of erbium ions in phosphate glass spheres. We also report on the effects that the interaction between the WGM modes of the glass sphere and an external metallic mirror has on the laser emission

Estimation of toxicity of chemical mixtures through modeling of chemical interactions.

The Agency for Toxic Substances and Disease Registry (ATSDR), in collaboration with the Dutch Organization for Applied Scientific Research (TNO) Nutrition and Food Research Institute, is conducting studies to evaluate the role of chemical interactions in the expression of toxicity from low-level exposure to combinations of chemicals. The goal of this collaborative effort is to use a weight-of-evidence (WOE) approach to estimate joint toxicity of some simple chemical mixtures and to compare the estimations with test results from animal toxicity studies. The WOE approach uses individual chemical dose-response assessments and algorithms that incorporate various assumptions regarding potential chemical interactions. Qualitative evaluations were prepared for binary combinations of chemicals for the effect of butyl hydroxyanisole on di(2-ethylhexyl)phthalate, the effect of stannous chloride on Cd chloride (CdCl2), and the effect of CdCl2 on loperamide. Analyses of these evaluations and their comparison with the conclusions of laboratory animal experiments indicate that the WOE approach can be used to estimate qualitatively the joint toxicity of such simple mixtures. To further test the utility of the WOE approach, qualitative and semiquantitative evaluations were prepared for two chemical mixtures--one with similarly acting halogenated aliphatics (trichloroethylene, tetrachloroethylene, hexachloro-1,3-butadiene[HCBD], and 1,1,2-trichloro-3,3,3-trifluoropropene [TCTFP]) and the other with dissimilarly acting nephrotoxic components (mercuric chloride, lysinolalanine, D-limonene, and HCBD). These two sets of data were used to estimate the overall toxicities of the mixtures using the WOE algorithm for the mixture. The comparison of the results of the estimated toxicity with experimentally determined toxicity of the mixture of similarly acting nephrotoxicants demonstrated that the WOE approach correctly adjusted for the observed interactions in experimental animal studies. However, this was not true for the mixture of dissimilarly acting nephrotoxicants. This could be attributed to the fact that WOE evaluations are based on dose additivity that postulates that all chemicals in a given mixture act in the same way--by the same mechanism--and differ only in their potencies. In these cases the WOE approach evaluations, based on consideration of common mechanisms for simple chemical mixtures, can lead to better estimates of joint toxicity of chemical mixtures than the default assumption of dose additivity. The results also show that the WOE evaluations should be target-organ specific because none of the models tested could approximate the observed responses in organs other than the target organs in the laboratory animal studies

Compound climate-pollution extremes in Santiago de Chile

Cities in the global south face dire climate impacts. It is in socioeconomically marginalized urban communities of the global south that the effects of climate change are felt most deeply. Santiago de Chile, a major mid-latitude Andean city of 7.7 million inhabitants, is already undergoing the so-called “climate penalty” as rising temperatures worsen the effects of endemic ground-level ozone pollution. As many cities in the global south, Santiago is highly segregated along socioeconomic lines, which offers an opportunity for studying the effects of concurrent heatwaves and ozone episodes on distinct zones of affluence and deprivation. Here, we combine existing datasets of social indicators and climate-sensitive health risks with weather and air quality observations to study the response to compound heat-ozone extremes of different socioeconomic strata. Attributable to spatial variations in the ground-level ozone burden (heavier for wealthy communities), we found that the mortality response to extreme heat (and the associated further ozone pollution) is stronger in affluent dwellers, regardless of comorbidities and lack of access to health care affecting disadvantaged population. These unexpected findings underline the need of a site-specific hazard assessment and a community-based risk management.</p

The Value of Suction Drainage Fluid Culture during Aseptic and Septic Orthopedic Surgery: A Prospective Study of 901 Patients

There are no guidelines on the value of suction drainage fluid culture (SDC), and it is difficult to determine whether the organisms cultured from suction drainage fluid samples are pathogenic or simply contaminants. We performed 2989 cultures of suction drainage fluid samples obtained, during a 1-year period, from 901 patients who underwent aseptic or septic orthopedic surgery (946 operations). The culture results were analyzed to evaluate their ability to detect postoperative infection after aseptic operations or to detect either a persistent or new episode of sepsis in patients known to have infection. For aseptic operations, the sensitivity of SDC was 25%, the specificity was 99%, the positive predictive value was 25%, and the negative predictive value was 99%. For septic operations, the sensitivity of SDC was 81%, the specificity was 96%, the positive predictive value was 87%, and the negative predictive value was 94%. We conclude that, for aseptic orthopedic surgery, SDC is not useful in detecting postoperative infection. However, for septic orthopedic surgery, it is of clinical importanc

Comparison of the clonogenic survival of A549 non-small cell lung adenocarcinoma cells after irradiation with low-dose-rate beta particles and high-dose-rate X-rays

Purpose: Lung cancer is the leading cause of cancer-related death. Among the new modalities to treat cancer, internal radiotherapy seems to be very promising. However, the achievable dose-rate is two orders of magnitude lower than the one used in conventional external radiotherapy, and data has to be collected to evaluate the cell response to highlight the potential effectiveness of low-dose-rate beta particles irradiation. This work investigates the phosphorus beta irradiation ( P) dose response on the clonogenicity of human A549 non-small cell lung adenocarcinoma cells and compares it to high-dose-rate X-irradiations results. Materials and methods: Cell survival was evaluated by a colony forming assay eight days after low-dose-rate P beta irradiations (0.8 Gy/h) and high-dose-rate X-ray irradiations (0.855 Gy/min). Results: Survival curves were obtained for both types of irradiations, and showed hyper-radiosensitivity at very low doses. Radiosensitivity parameters were obtained by using the linear-quadratic and induced-repair models. Conclusions: Comparison with high-dose-rate X-rays shows a similar surviving fraction, confirming the effectiveness of beta particles for tumor sterilization. © 2012 Informa UK, Ltd