Sizes and shapes of 10-Ma Distal fall pyroclasts in the Ogallala gGroup, Nebraska

Size distributions of distal ashfall particles from correlated 10-Ma layers in Nebraska, measured using laser diffraction methods, are lognormal with mode diameters of ∼90 mm. This ashfall is ∼100% bubble-wall shards of rhyolite glass and apparently represents a distal ashfall from an eruption 1400 km away. Measured terminal velocities of these ash particles are 0.2–18 cm/s, consistent with Stokes Law settling of spherical particles with diameters of 9–50 mm. Surface area of the ash particles, measured with gas adsorption, is 20–30 times the surface area of equivalent Stokes spheres. These results highlight the effects of shape and atmospheric drag in distal ashfalls. They also highlight atmospheric transport and fallout of distal ashfall particles, because these deposits resemble many other ashfalls preserved in the Great Plains of North America throughout the Tertiary and Quaternary. Because the ashfalls preserve major mammalian death assemblages, they demonstrate that deposits with modes of optical diameters 1100 mm are still hazardous by aerodynamic definitions of lung disease risk and include particles substantially within hazardous PM10 ranges. The aerodynamically fine particle size may lead to substantial aeolian redistribution, causing local thicknesses of 12 m. Overall, the ashfall thicknesses observed are at least several times larger than would be expected based on exponential thinning from the volcano. Shape measurements of distal ash particles may be necessary to assess risk. The possible health risks in the central United States from a future rhyolitic eruption in the western United States may be significant

Reduction of Dopamine Level Enhances the Attractiveness of Male Drosophila to Other Males

Dopamine is an important neuromodulator in animals and its roles in mammalian sexual behavior are extensively studied. Drosophila as a useful model system is widely used in many fields of biological studies. It has been reported that dopamine reduction can affect female receptivity in Drosophila and leave male-female courtship behavior unaffected. Here, we used genetic and pharmacological approaches to decrease the dopamine level in dopaminergic cells in Drosophila, and investigated the consequence of this manipulation on male homosexual courtship behavior. We find that reduction of dopamine level can induce Drosophila male-male courtship behavior, and that this behavior is mainly due to the increased male attractiveness or decreased aversiveness towards other males, but not to their enhanced propensity to court other males. Chemical signal input probably plays a crucial role in the male-male courtship induced by the courtees with reduction of dopamine. Our finding provides insight into the relationship between the dopamine reduction and male-male courtship behavior, and hints dopamine level is important for controlling Drosophila courtship behavior

Dipstick Test for Rapid Diagnosis of Shigella dysenteriae 1 in Bacterial Cultures and Its Potential Use on Stool Samples

International audienceBACKGROUND: We describe a test for rapid detection of S. dysenteriae 1 in bacterial cultures and in stools, at the bedside of patients. METHODOLOGY/PRINCIPAL FINDINGS: The test is based on the detection of S. dysenteriae 1 lipopolysaccharide (LPS) using serotype 1-specific monoclonal antibodies coupled to gold particles and displayed on a one-step immunochromatographic dipstick. A concentration as low as 15 ng/ml of LPS was detected in distilled water and in reconstituted stools in 10 minutes. In distilled water and in reconstituted stools, an unequivocal positive reaction was obtained with 1.6×10⁶ CFU/ml and 4.9×10⁶ CFU/ml of S. dysenteriae 1, respectively. Optimal conditions to read the test have been determined to limit the risk of ambiguous results due to appearance of a faint yellow test band in some negative samples. The specificity was 100% when tested with a battery of Shigella and unrelated strains in culture. When tested on 328 clinical samples in India, Vietnam, Senegal and France by laboratory technicians and in Democratic Republic of Congo by a field technician, the specificity (312/316) was 98.7% (95% CI:96.6-99.6%) and the sensitivity (11/12) was 91.7% (95% CI:59.8-99.6%). Stool cultures and the immunochromatographic test showed concordant results in 98.4 % of cases (323/328) in comparative studies. Positive and negative predictive values were 73.3% (95% CI:44.8-91.1%) and 99.7% (95% CI:98-100%). CONCLUSION: The initial findings presented here for a simple dipstick-based test to diagnose S. dysenteriae 1 demonstrates its promising potential to become a powerful tool for case management and epidemiological surveys

Un magazine laïque :éditorial

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Histoire de l'athéisme en Belgique

Parmi les belges qui déclarent leur conviction ou leur non-conviction religieuse dans les récents sondages d'opinion internationaux, des pourcentages importants de répondants se disent athées. Pourtant, il n'existait jusqu'ici en Belgique aucun ouvrage global qui analyse le rôle de l'athéisme dans l'histoire intellectuelle, politique et culturelle du pays. Le présent ouvrage est le fruit d'une collaboration entre Liberas (Gand) et l'Association Belge des Athées. Avec l'appui de la Communauté flamande, de la Fédération Wallonie-Bruxelles et des organismes coupoles du mouvement laïque, les deux associations ont uni leurs forces pour couvrir, d'une manière accessible et scientifique, le sujet dans la Belgique toute entière pour les XIXe et XXe siècles. Dans ce volume, la négation de l'existence de Dieu n'est pas traitée seulement d'un point de vue philosophique, mais aussi à travers les débats dans les universités, le monde scientifique, poétique et laïque, ainsi que dans les arts et les lettres. L'athéisme y est étudié comme un phénomène social qui a rencontré beaucoup de résistance. De nombreux scientifiques, penseurs, écrivains et artistes éminents, de Félicien Rops à Léo Apostel, jouent un rôle dans cette histoire et trouvent leur place dans l'ouvrage. Les auteurs des contributions sont des spécialistes issus d'universités ou d'institutions patrimoniales.info:eu-repo/semantics/publishe