Synchrotron Emissions in GRB Prompt Phase Using a Semi Leptonic and Hadronic Model

In this communication devoted to the prompt emission of GRBs, we claim that some important parameters associated to the magnetic field, such as its index profile, the index of its turbulence spectrum and its level of irregularities, will be measurable with GLAST. In particular the law relating the peak energy Epeak with the total energy E (like Amati's law) constrains the turbulence spectrum index and, among all existing theories of MHD turbulence, is compatible with the Kolmogorov scaling only. Thus, these data will allow a much better determination of the performances of GRBs as particle accelerators. This opens the possibility to characterize both electron and proton acceleration more seriously. We discuss the possible generation of UHECRs and of its signature through GeV-TeV synchrotron emission.Comment: 30th International Cosmic Ray Conference (ICRC2007) - Proceeding #107

Intrinsic Variability and Field Statistics for the Vela Pulsar: 2. Systematics and Single-Component Fits

Individual pulses from pulsars have intensity-phase profiles that differ widely from pulse to pulse, from the average profile, and from phase to phase within a pulse. Widely accepted explanations do not exist for this variability or for the mechanism producing the radiation. The variability corresponds to the field statistics, particularly the distribution of wave field amplitudes, which are predicted by theories for wave growth in inhomogeneous media. This paper shows that the field statistics of the Vela pulsar (PSR B0833-45) are well-defined and vary as a function of pulse phase, evolving from Gaussian intensity statistics off-pulse to approximately power-law and then lognormal distributions near the pulse peak to approximately power-law and eventually Gaussian statistics off-pulse again. Detailed single-component fits confirm that the variability corresponds to lognormal statistics near the peak of the pulse profile and Gaussian intensity statistics off-pulse. The lognormal field statistics observed are consistent with the prediction of stochastic growth theory (SGT) for a purely linear system close to marginal stability. The simplest interpretations are that the pulsar's variability is a direct manifestation of an SGT state and the emission mechanism is linear (either direct or indirect), with no evidence for nonlinear mechanisms like modulational instability and wave collapse which produce power-law field statistics. Stringent constraints are placed on nonlinear mechanisms: they must produce lognormal statistics when suitably ensemble-averaged. Field statistics are thus a powerful, potentially widely applicable tool for understanding variability and constraining mechanisms and source characteristics of coherent astrophysical and space emissions.Comment: 11 pages, 12 figures. Accepted by Monthly Notices of the Royal Astronmical Society in April 200

Factors Associated With Late Stage Diagnosis of Cervical Cancer in the United States

Cervical cancer represents a significant public health problem in the United States. According to the Centers for Disease Control and Prevention, the prognosis is related to stage at diagnosis, with the 5-year survival rate being 91.2% for early stage disease and only 17.0% for those with late stage disease. There is a gap in the literature examining the association of insurance status with late stage cervical cancer diagnosis across a large segment of the United States population. There is also a gap in the literature examining women residing in the United States with late stage cervical cancer diagnosis and identifying their country of birth. Guided by Andersen\u27s behavioral model of healthcare utilization, this study used the Surveillance, Epidemiology, and End Results database, which includes over 28% of the United States population. The independent variables used were insurance, country of birth, race/ethnicity, age at diagnosis, and marital status. The dependent variable was stage at diagnosis. This cross sectional study included data from 7,445 women across the United States for the years 2008-2012. Two-way tests of association and logistic regression were used to analyze the data. The logistic regression (full model) was statistically significant and found that women born outside of the United States have a lower risk of late stage cervical cancer diagnosis and that unmarried women have a greater risk of late stage diagnosis. This study should send a signal to healthcare providers, as well as public health organizations, to direct their actions toward targeting groups that are now being diagnosed with late stage disease

Cinétique d'accumulation et rétention d'espèces du mercure chez l'étoile de mer Leptasterias polaris: une expérience de transfert trophique à long terme

Dans le cadre de travaux sur le rôle des échinodermes dans le cycle biogéochimique de certains métaux traces en milieu côtier, une étude de l'accumulation et de la rétention d'espèces chimiques du mercure a été menée avec l'étoile de mer Leptasterias polaris sur une période de 40 jours. Les étoiles de mer ont été divisées en deux groupes et nourries avec des moules contaminées soit au méthylmercure (MeHg) (14 mg.kg-1), soit au mercure inorganique (13 mg.kg-1). Les résultats montrent une vitesse d'accumulation dans le système digestif de 0,22 mg.kg-1.j-1 pour le Hg inorganique et 0,17 mg.kg-1.j-1 pour le MeHg. Ces vitesses sont 10 à 15 fois moins importantes dans les gonades et l'endosquelette. Pour le Hg inorganique, la charge relative dans les différents organes analysés se fixe après quelques jours et demeure stable jusqu'à la fin de l'expérience. Pour le MeHg, au contraire, cette charge relative passe progressivement du système digestif vers les gonades et l'exosquelette tout au long de l'expérience. Le pourcentage de rétention (%) demeure constant pour le Hg inorganique (51 ± 13%) mais il augmente régulièrement pour le MeHg, atteignant 90-95% vers la fin de l'exposition. L'application d'un modèle cinétique simple, basé sur un processus d'échange ionique, a permis de calculer des constantes de vitesse d'échange entre le digestat et le tissu digestif. Le MeHg s'échange plus vite entre la solution et les sites, mais semble mettre un peu plus de temps à voyager jusqu'aux organes de bioaccumulation. En conclusion, l'étoile L. polaris, par sa taille, sa longévité et sa grande efficacité à digérer tout ce qui est ingéré, semble en mesure de jouer un rôle important à la fois dans la séquestration du MeHg et la remise en solution du Hg inorganique.In spite of a large body of work on the uptake of trace metals in aquatic organisms in the last two decades, very little attention has been devoted to echinoderms (urchins, starfish, and sea cucumbers, among the most important ones), a large group of invertebrates forming a major component of most coastal ecosystems. In the course of our research program on the role of echinoderms in the biogeochemical cycling of some trace metals in coastal environment, an experiment has been conducted on the uptake and the retention of mercury species with starfish Leptasterias polaris over a 40-day exposure period.Starfish were caught near Pointe-au-Père (Québec, Canada) and were acclimatized to laboratory conditions for 10 days in a flow-through aquarium. Forty stars (84 ± 14 g) were divided in two groups, kept in two aquariums, one for inorganic mercury and the other for methylmercury exposure. Animals were isolated from each other by mean of small 65-mm net cubicles allowing free circulation of seawater at a rate of 2 L.min-1. This flow rate provided a rapid renewal of seawater and ensured the elimination of any soluble mercury excreted during the course of the experiment. Control starfish receiving only uncontaminated mussels were also maintained in both aquariums to monitor the possible uptake of mercury from seawater. Blue mussels were collected in the vicinity of Pointe-au-Père and were contaminated following a technique described elsewhere (PELLETIER and LAROCQUE, 1987). Average levels of inorganic mercury and methylmercury (MeHg) in mussels were 13 ± 3 and 14 ± 4 mg.kg-1, respectively. Each starfish received one contaminated mussel per day over a 40-day period. Mussels were weighed before to be introduced in cages and their empty shells weighed again after ingestion by starfish in order to evaluate the amount of food and mercury taken up daily by each star. Two starfish were sampled in each aquarium every five days and dissected for pyloric caeca, gonads, and endoskeleton. Coelomic fluid was also collected. Both mercury species were analysed as total mercury (assuming a preservation level of ± 85-90% of the speciation during the course of the experiment) in biological tissues by cold vapour atomic adsorption spectrophotometry (detection limit=0.005 mg.kg-1 ww). The coefficient of variation was ± 15% and the recovery yield of MeHg-spiked samples was 92 ± 12%.The concentration of inorganic mercury reached 7.56 mg.kg-1 (wet weight) in pyloric caeca and the uptake rate was 0.22 mg.kg-1.d-1. Concentrations in gonads and endoskeleton were 10 to 20 times lower than in caeca (Fig. 1). The uptake rate of MeHg (0.17 mg.kg-1d-1) was slightly slower and the maximum concentration reached in caeca was 5.34 mg.kg-1. Mercury concentrations found in coelomic fluid were low and at least 100 times smaller than those in ceaca. No mercury was found in tissues of control starfish indicating that mercury excreted by diffusion in water by contaminated starfish was not re-adsorbed by other starfish in aquariums. The mercury load in each organ of stars was calculated and expressed as a percent (%) of total Hg uptake for each chemical species (Fig. 2). The inorganic Hg loads in pyloric caeca, gonads and endoskeleton reached a steady-state after only 10 days and remained unchanged up to the end of the experiment. The behaviour of MeHg was totally different as the loads in caeca decreased from 95% to 65% but increased from almost zero up to 30% in endoskeleton. Finally, the retention (%) of mercury species was calculated by dividing the actual total amount of mercury in each starfish by the total amount of mercury received from mussels (Fig. 3). The retention of inorganic Hg was about 50% throughout the exposure period whereas the retention of MeHg increased up to 90-95% at the end of the experiment.A kinetic model, based upon the assumption that the uptake process of Hg species in the digestive system is quite similar to an ion-exchange adsorption mechanism between a contamination solution and a solid surface, was developed. The integrated equation of the rate law was expressed as: (ln(C0-q))/q0-q = K'(C0m-q0)t + ln (C0m/q0)were Co is the initial concentration of mercury in the prey, qo is the maximun amount of mercury being absorbed, and m stands for the wet weight of the animal. This equation allowed the plot of its left-hand side against time and the slope provided an estimation of an apparent exchange rate constant for each mercury species (Fig. 4). The rate constant k'MeHg was slightly higher than k'Hg, indicating a faster exchange rate for MeHg between digested mussel tissues and binding sites (and also between sites) in caeca. However, a faster exchange rate do not mean a faster uptake rate because transport rate towards other organs also play an important role in the whole bioaccumulation process. In conclusion, starfish, by its ability to digest all ingested tissues, seems to be in a position to play a major role in the sequestration of methylmercury (high retention) from mussels and from other potential preys and in recycling inorganic mercury in solution (low retention). Starfish can be seen as "marine digester" which engulfs bivalves and other invertebrates (following species) and sends back soluble metabolites and trace metals which have not been bioaccumulated

Construction et installation du LHC

L’installation du LHC a pris, en 2002, une nouvelle dimension avec le début des travaux de la machine en parallèle à ses futures expériences. La première phase des travaux pour le LHC a été la mise en place des services généraux électriques et des tuyauteries d’eau de refroidissement dans le secteur 7/8. Les premières lignes cryogéniques (QRL) seront acheminées au mois de juin. Pour les expériences ALICE et LHC B, après les dernières opérations de démontage, les premiers travaux d’installation des futurs détecteurs ont pu commencer. ATLAS a pu également débuter l’installation de son infrastructure au point 1 avec le début des travaux de charpente dans USA 15. Pour CMS au point 5, la réalisation d’une grande partie de son spectaculaire aimant, est l’objet de nombreuses visites. Le montage des autres parties de son détecteur représentant également une large part d’activité sur d’autres sites

Une excentrique au coeur de l’industrie : Ray Lewis et le Canadian Moving Picture Digest

Ray Lewis fut, de 1918 à 1954, la rédactrice en chef du Canadian Moving Picture Digest, le premier journal corporatif relatif à l’industrie cinématographique canadienne. La personnalité et le parcours exceptionnels de Lewis peuvent expliquer sa présence — en apparence inusitée — à la tête d’une publication s’adressant à une industrie essentiellement masculine. Lewis milita ardemment dans les pages du Digest pour l’organisation et la défense des exploitants indépendants, de même que pour la création d’une culture nationale canadienne se démarquant du modèle américain.In 1918, Ray Lewis became editor of Canada’s principal film trade journal, the Canadian Moving Picture Digest. She soon owned it, too, and stayed in charge until her death in 1954. If it was uncommon enough for a woman to be journalist and editor, it was truly exceptional for a woman to be in a powerful position in the film industry. Lewis’ strong character carried into her work as self-appointed protector of Canadian exhibitors’ independence. She used the Digest to agitate against Hollywood control, and tried to promote a distinctly Canadian culture of movie-going

Ray Lewis

For nearly four decades, Ray Lewis was one of the most vocal representatives of the Canadian film industry. The trade journal she edited from the late 1910s until the mid-1950s, the Canadian Moving Picture Digest, kept the nation’s film exhibitors informed on a wide variety of topics. It also permitted Lewis to mount campaigns dealing with some of the most vital issues of the day, such as the defense of independent exhibitors and the quest for a distinctly Canadian film culture

Olfactory proteins mediating chemical communication in the navel orangeworm moth, Amyelois transitella.

BackgroundThe navel orangeworm, Amyelois transitella Walker (Lepidoptera: Pyralidae), is the most serious insect pest of almonds and pistachios in California for which environmentally friendly alternative methods of control--like pheromone-based approaches--are highly desirable. Some constituents of the sex pheromone are unstable and could be replaced with parapheromones, which may be designed on the basis of molecular interaction of pheromones and pheromone-detecting olfactory proteins.MethodologyBy analyzing extracts from olfactory and non-olfactory tissues, we identified putative olfactory proteins, obtained their N-terminal amino acid sequences by Edman degradation, and used degenerate primers to clone the corresponding cDNAs by SMART RACE. Additionally, we used degenerate primers based on conserved sequences of known proteins to fish out other candidate olfactory genes. We expressed the gene encoding a newly identified pheromone-binding protein, which was analyzed by circular dichroism, fluorescence, and nuclear magnetic resonance, and used in a binding assay to assess affinity to pheromone components.ConclusionWe have cloned nine cDNAs encoding olfactory proteins from the navel orangeworm, including two pheromone-binding proteins, two general odorant-binding proteins, one chemosensory protein, one glutathione S-transferase, one antennal binding protein X, one sensory neuron membrane protein, and one odorant receptor. Of these, AtraPBP1 is highly enriched in male antennae. Fluorescence, CD and NMR studies suggest a dramatic pH-dependent conformational change, with high affinity to pheromone constituents at neutral pH and no binding at low pH

Transport of Cosmic Rays in Chaotic Magnetic Fields

The transport of charged particles in disorganised magnetic fields is an important issue which concerns the propagation of cosmic rays of all energies in a variety of astrophysical environments, such as the interplanetary, interstellar and even extra-galactic media, as well as the efficiency of Fermi acceleration processes. We have performed detailed numerical experiments using Monte-Carlo simulations of particle propagation in stochastic magnetic fields in order to measure the parallel and transverse spatial diffusion coefficients and the pitch angle scattering time as a function of rigidity and strength of the turbulent magnetic component. We confirm the extrapolation to high turbulence levels of the scaling predicted by the quasi-linear approximation for the scattering frequency and parallel diffusion coefficient at low rigidity. We show that the widely used Bohm diffusion coefficient does not provide a satisfactory approximation to diffusion even in the extreme case where the mean field vanishes. We find that diffusion also takes place for particles with Larmor radii larger than the coherence length of the turbulence. We argue that transverse diffusion is much more effective than predicted by the quasi-linear approximation, and appears compatible with chaotic magnetic diffusion of the field lines. We provide numerical estimates of the Kolmogorov length and magnetic line diffusion coefficient as a function of the level of turbulence. Finally we comment on applications of our results to astrophysical turbulence and the acceleration of high energy cosmic rays in supernovae remnants, in super-bubbles, and in jets and hot spots of powerful radio-galaxies.Comment: To be published in Physical Review D, 20 pages 9 figure