Magnetization of polar ice: a measurement of terrestrial dust and extraterrestrial fallout

Laboratory-induced remanent magnetization of polar ice constitutes a measurement of the magnetization carried by the ferromagnetic dust particles in the ice. This non-destructive technique provides a novel kind of information on the dust deposited on the surface of polar ice sheets. Measurements made on ice samples from Greenland (North GRIP ice core) and Antarctica (Vostok and EPICA-Dome C ice cores) allowed the recognition of a fraction of magnetic minerals in ice whose concentration and magnetic properties are directly related to that of insoluble dust. The source of this fraction of magnetic minerals thus appears closely related to terrestrial dust transport and deposition and its magnetic properties are informative of the dust provenance areas. The rock-magnetic properties of the dust may reflect distinct changes of dust source areas from glacial to interglacial periods in agreement with and adding further information to the isotopic (87Sr/86Sr and 143Nd/144Nd) analyses. A second magnetic fraction consists of particles of nanometric size, which are superparamagnetic at freezer temperature and whose concentration is independent of the mass of aerosol dust found in the ice. The source of these nanometric-sized magnetic particles is ascribed to fallout of “meteoric smoke” and their concentration in ice was found to be compatible with the extraterrestrial fallout inferred from Ir concentrations. The diameter of the smoke particles as inferred from magnetic measurements is in the range of about 7–20 nm

Magnetization of polar ice: a measurement of terrestrial dust and extraterrestrial fallout

Laboratory-induced remanent magnetization of polar ice constitutes a measurement of the magnetization carried by the ferromagnetic dust particles in the ice. This non-destructive technique provides a novel kind of information on the dust deposited on the surface of polar ice sheets. Measurements made on ice samples from Greenland (North GRIP ice core) and Antarctica (Vostok and EPICA-Dome C ice cores) allowed the recognition of a fraction of magnetic minerals in ice whose concentration and magnetic properties are directly related to that of insoluble dust. The source of this fraction of magnetic minerals thus appears closely related to terrestrial dust transport and deposition and its magnetic properties are informative of the dust provenance areas. The rock-magnetic properties of the dust may reflect distinct changes of dust source areas from glacial to interglacial periods in agreement with and adding further information to the isotopic (87Sr/86Sr and 143Nd/144Nd) analyses. A second magnetic fraction consists of particles of nanometric size, which are superparamagnetic at freezer temperature and whose concentration is independent of the mass of aerosol dust found in the ice. The source of these nanometric-sized magnetic particles is ascribed to fallout of “meteoric smoke” and their concentration in ice was found to be compatible with the extraterrestrial fallout inferred from Ir concentrations. The diameter of the smoke particles as inferred from magnetic measurements is in the range of about 7–20 nm

Association between Ambient Noise Exposure and School Performance of Children Living in An Urban Area: A Cross-Sectional Population-Based Study

16 pages Article disponible à l'adresse suivante : http://link.springer.com/article/10.1007%2Fs11524-013-9843-6International audienceMost of the studies investigating the effects of the external noise on children's school performance have concerned pupils in schools exposed to high levels due to aircraft or freeway traffic noise. However, little is known about the consequences of the chronic ambient noise exposure at a level commonly encountered in residential urban areas. This study aimed to assess the relationship between the school performance of 8- to 9-year-old-children living in an urban environment and their chronic ambient noise exposure at home and at school. The children's school performances on the national standardized assessment test in French and mathematics were compared with the environmental noise levels. Children's exposure to ambient noise was calculated in front of their bedrooms (Lden) and schools (LAeq,day) using noise prediction modeling. Questionnaires were distributed to the families to collect potential confounding factors. Among the 746 respondent children, 586 were included in multilevel analyses. On average, the LAeq,day at school was 51.5 dB (SD= 4.5 dB; range = 38-58 dB) and the outdoor Lden at home was 56.4 dB (SD= 4.4 dB; range = 44-69 dB). LAeq,day at school was associated with impaired mathematics score (p = 0.02) or impaired French score (p = 0.01). For a + 10 dB gap, the French and mathematics scores were on average lower by about 5.5 points. Lden at home was significantly associated with impaired French performance when considered alone (p < 10(-3)) and was borderline significant when the combined home-school exposure was considered (p = 0.06). The magnitude of the observed effect on school performance may appear modest, but should be considered in light of the number of people who are potentially chronically exposed to similar environmental noise levels

Rapport de sondages et d'analyses, Le Kilian et les carrières anciennes de trachyte dans la Chaîne des Puys (Puy-de-Dôme)

En 2008, l'existence de carrières souterraines médiévales avait été mise en évidence dans la pente ouest du Bois de Manson qui domine la dépression du Cratère Kilian, au pied sud du puy de Dôme. En 2009-2010, des sondages et prospections ont été étendus à tout l'ensemble du Kilian de façon à préciser l'étendue et, si possible, la chronologie de son exploitation dans le passé. Ces travaux ont permis d'observer, dans le fond du cratère et sur son flanc interne ouest, des amoncellements de déblais d'un volume considérable, témoignant d'une extraction de roche à grande échelle durant le haut Moyen Âge et très probablement aussi à l'époque gallo-romaine. Une nouvelle carrière souterraine a été découverte dans la pente interne ouest du cratère. La base du remplissage de cette carrière a livré des charbons datés entre la fin du IV e siècle et le début du VI e siècle par le radiocarbone, tandis que le sommet du remplissage contenait des tessons de céramique datables, par leur typologie, de la fin du V e siècle au début du VIII e siècle. L'état actuel des investigations conduit à faire l'hypothèse que les gallo-romains ont exploité, au fond du cratère, un trachyte compact dont on ne trouve aujourd'hui que les déchets de taille, et dont les affleurements sont masqués par les déblais, tandis que les artisans du Moyen Âge ont recherché un trachyte plus tendre dans les pentes hautes du cratère. Le Kilian doit donc s'ajouter aux trois sources actuellement connues de trachyte d'oeuvre dans le passé, à savoir les volcans Sarcoui, Aumône (ou petit Suchet) et Cliersou. Dès cette découverte, en 2008, s'est posée la question de savoir quelle part éventuelle le trachyte du Kilian avait pu prendre dans la construction du temple de Mercure au sommet du puy de Dôme et dans l'agglomération gallo-romaine située au col de Ceyssat. Pour y répondre, une campagne d'analyses géochimiques et pétrographiques été engagée pour caractériser, aux fins de comparaison, non seulement les trachytes du Kilian et ceux des ruines gallo-romaines, mais, de plus, les trachytes du Cliersou, de l'Aumône et du Sarcoui. Ces analyses ont finalement montré qu'il est possible de faire une discrimination statistiquement significative entre les différents trachytes étudiés, à l'exception de ceux du couple Cliersou-Aumône dont les laves sont très peu différentes les unes des autres. Le résultat le plus remarquable est que tous les trachytes gallo-romains échantillonnés (dont 10 échantillons distincts au temple de Mercure et 10 au col de Ceyssat) se rattachent sans ambiguïté au Kilian. En toute rigueur, ces nouvelles données ne permettent pas d'exclure sans appel la possibilité d'utilisation à l'époque gallo-romaine, au temple de Mercure et au col de Ceyssat, de trachytes provenant d'autres sources que le Kilian (cas des chaperons de mur du col de Ceyssat, provenant du puy de Dôme). Cependant, il faut ajouter qu'un examen visuel des trachytes d'oeuvre dans ces deux sites, portant sur un nombre de moellons et d'éléments architecturaux bien supérieur au nombre de ceux qui ont été analysés, conduit à conclure que leur source est probablement commune. Cette conclusion est basée sur un faciès minéralogique particulier, observable à l'oeil nu ou à la loupe

CC9 Livestock-Associated Staphylococcus aureus Emerges in Bloodstream Infections in French Patients Unconnected With Animal Farming

We report 4 bloodstream infections associated with CC9 agr type II Staphylococcus aureus in individuals without animal exposure. We demonstrate, by microarray analysis, the presence of egc cluster, fnbA, cap operon, lukS, set2, set12, splE, splD, sak, epiD, and can, genomic features associated with a high virulence potential in human

The P2Y1 receptor is involved in the maintenance of glucose homeostasis and in insulin secretion in mice

Pancreatic β cells express several P2 receptors including P2Y1 and the modulation of insulin secretion by extracellular nucleotides has suggested that these receptors may contribute to the regulation of glucose homeostasis. To determine whether the P2Y1 receptor is involved in this process, we performed studies in P2Y1 mice. In baseline conditions, P2Y1-mice exhibited a 15% increase in glycemia and a 40% increase in insulinemia, associated with a 10% increase in body weight, pointing to a role of the P2Y1 receptor in the control of glucose metabolism. Dynamic experiments further showed that P2Y1-mice exhibited a tendency to glucose intolerance. These features were associated with a decrease in the plasma levels of free fatty acid and triglycerides. When fed a lipids and sucrose enriched diet for 15 weeks, the two genotypes no longer displayed any significant differences. To determine whether the P2Y1 receptor was directly involved in the control of insulin secretion, experiments were carried out in isolated Langerhans islets. In the presence of high concentrations of glucose, insulin secretion was significantly greater in islets from P2Y1-mice. Altogether, these results show that the P2Y1 receptor plays a physiological role in the maintenance of glucose homeostasis at least in part by regulating insulin secretion

Reconstruction of primary vertices at the ATLAS experiment in Run 1 proton–proton collisions at the LHC

This paper presents the method and performance of primary vertex reconstruction in proton–proton collision data recorded by the ATLAS experiment during Run 1 of the LHC. The studies presented focus on data taken during 2012 at a centre-of-mass energy of √s=8 TeV. The performance has been measured as a function of the number of interactions per bunch crossing over a wide range, from one to seventy. The measurement of the position and size of the luminous region and its use as a constraint to improve the primary vertex resolution are discussed. A longitudinal vertex position resolution of about 30μm is achieved for events with high multiplicity of reconstructed tracks. The transverse position resolution is better than 20μm and is dominated by the precision on the size of the luminous region. An analytical model is proposed to describe the primary vertex reconstruction efficiency as a function of the number of interactions per bunch crossing and of the longitudinal size of the luminous region. Agreement between the data and the predictions of this model is better than 3% up to seventy interactions per bunch crossing

BRN2 is a non-canonical melanoma tumor-suppressor

©2021. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This document is the Published Manuscript version of a Published Work that appeared in final form in Nature Communications. To access the final edited and published work see https://doi.org/10.1038/s41467-021-23973-5While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, in a BrafV600E PtenF/+ context, we show that BRN2 haplo-insufficiency promotes melanoma initiation and metastasis. However, metastatic colonization is less efficient in the absence of Brn2. Mechanistically, BRN2 directly induces PTEN expression and in consequence represses PI3K signaling. Moreover, MITF, a BRN2 target, represses PTEN transcription. Collectively, our results suggest that on a PTEN heterozygous background somatic deletion of one BRN2 allele and temporal regulation of the other allele elicits melanoma initiation and progressio