The effect of flowering stage in wheat on the infection efficiency of Ustilago tritici

Dans l'ouest du Canada, la détermination du niveau de résistance de lignées de blé (Triticum aestivum) à l’ Ustiiago tritici est habituellement faite par inoculation lorsque les plantes atteignent le stade mi-anthèse du développement de l'épi. Par contre, il n'est pas toujours possible de faire les inoculations à ce stade, ainsi des inoculations sont parfois faites quelques jours avant ou après la mi-anthèse. L'objectif de cette étude était de déterminer si l'inoculation, par la méthode du vide partiel, d'épis de blé avec l’U. tritici à différents stades du développement de l'épi pouvait avoir un effet sur le nombre de grains viables par épi et, ultérieurement, sur le pourcentage de plantes cariées issues de grains inoculés. À chaque année durant 5 ans, quatre lignées de blé ont été inoculées au champ à trois différents stades du développement de l'épi. Les stades du développement de l'épi étudiés étaient la pré-anthèse, la mi-anthèse (les anthères à chaque extrémité de l'épi sont déhiscentes alors que celles du centre sont jaunes) et la post-anthèse (toutes les anthères sont déhiscentes). Il y avait des différences significatives entre les quatre lignées de blé et les 5 années de l'étude quant au nombre de grains viables par épi et le pourcentage de plantes cariées. Un nombre de grains viables par épi plus grand et un pourcentage plus faible de plantes cariées ont été significativement obtenus avec l'inoculation post-anthèse. Nous concluons que l'inoculation de l’Ustilago tritici par la méthode du vide partiel doit être faite au stade préanthèse ou mi-anthèse du développement de l'épi de blé afin de minimiser les effets négatifs de la maturité sur l'efficacité d'infection.In general, in western Canada, the inoculation of wheat (Triticum aestivum) lines to determine the level of resistance to Ustiiago tritici occurs when the plants are at the mid-anthesis stage of spike development. However, it is not always possible to inoculate at this stage so occasionally inoculations are done a few days before or after mid-anthesis. The objective of this study was to determine if inoculation of wheat spikes with U. tritici at different stages of spike development using the partial-vacuum method affected the number of viable seed per spike and subsequent percentage of smutted plants grown from inoculated seed. Four lines of wheat were inoculated at three different stages of spike development in the field each year for 5 years. The stages of spike development studied were preanthesis, mid-anthesis (anthers at either end of the spike were dehisced while those in the middle of the spike were yellow), and post-anthesis (all anthers dehisced). There were significant differences among the four wheat lines and the 5 years of the study for the number of viable seed per spike and the percent of smutted plants. Inoculation at post-anthesis resulted in a significantly greater number of viable seed per spike and lower percentage of smutted plants. We conclude that the partial-vacuum method of inoculation with Ustiiago tritici should be done at the pre- or midanthesis stage of wheat head development to minimize the negative effect of maturity on infection efficiency

Magnetar outbursts: an observational review

Transient outbursts from magnetars have shown to be a key property of their emission, and one of the main way to discover new sources of this class. From the discovery of the first transient event around 2003, we now count about a dozen of outbursts, which increased the number of these strongly magnetic neutron stars by a third in six years. Magnetar outbursts might involve their multi-band emission resulting in an increased activity from radio to hard X-ray, usually with a soft X-ray flux increasing by a factor of 10-1000 with respect to the quiescent level. A connected X-ray spectral evolution is also often observed, with a spectral softening during the outburst decay. The flux decay times vary a lot from source to source, ranging from a few weeks to several years, as also the decay law which can be exponential-like, a power-law or even multiple power-laws can be required to model the flux decrease. We review here on the latest observational results on the multi-band emission of magnetars, and summarize one by one all the transient events which could be studied to date from these sources.Comment: 34 pages, 6 figures. Chapter of the Springer Book ASSP 7395 "High-energy emission from pulsars and their systems", proceeding of the Sant Cugat Forum on Astrophysics (12-16 April 2010). Review updated to January 201

Large, binge-type meals of high fat diet change feeding behaviour and entrain food anticipatory activity in mice

Copyright © 2014. Published by Elsevier Ltd.Peer reviewedPublisher PD

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare

Measurement of single pi0 production in neutral current neutrino interactions with water by a 1.3 GeV wide band muon neutrino beam

Neutral current single pi0 production induced by neutrinos with a mean energy of 1.3 GeV is measured at a 1000 ton water Cherenkov detector as a near detector of the K2K long baseline neutrino experiment. The cross section for this process relative to the total charged current cross section is measured to be 0.064 +- 0.001 (stat.) +- 0.007 (sys.). The momentum distribution of produced pi0s is measured and is found to be in good agreement with an expectation from the present knowledge of the neutrino cross sections.Comment: 6 pages, 4 figures, Submitted to Phys. Lett.

Gamma-Ray Bursts: The Underlying Model

A pedagogical derivation is presented of the ``fireball'' model of gamma-ray bursts, according to which the observable effects are due to the dissipation of the kinetic energy of a relativistically expanding wind, a ``fireball.'' The main open questions are emphasized, and key afterglow observations, that provide support for this model, are briefly discussed. The relativistic outflow is, most likely, driven by the accretion of a fraction of a solar mass onto a newly born (few) solar mass black hole. The observed radiation is produced once the plasma has expanded to a scale much larger than that of the underlying ``engine,'' and is therefore largely independent of the details of the progenitor, whose gravitational collapse leads to fireball formation. Several progenitor scenarios, and the prospects for discrimination among them using future observations, are discussed. The production in gamma- ray burst fireballs of high energy protons and neutrinos, and the implications of burst neutrino detection by kilometer-scale telescopes under construction, are briefly discussed.Comment: In "Supernovae and Gamma Ray Bursters", ed. K. W. Weiler, Lecture Notes in Physics, Springer-Verlag (in press); 26 pages, 2 figure

Magnetic Reconnection in Extreme Astrophysical Environments

Magnetic reconnection is a basic plasma process of dramatic rearrangement of magnetic topology, often leading to a violent release of magnetic energy. It is important in magnetic fusion and in space and solar physics --- areas that have so far provided the context for most of reconnection research. Importantly, these environments consist just of electrons and ions and the dissipated energy always stays with the plasma. In contrast, in this paper I introduce a new direction of research, motivated by several important problems in high-energy astrophysics --- reconnection in high energy density (HED) radiative plasmas, where radiation pressure and radiative cooling become dominant factors in the pressure and energy balance. I identify the key processes distinguishing HED reconnection: special-relativistic effects; radiative effects (radiative cooling, radiation pressure, and Compton resistivity); and, at the most extreme end, QED effects, including pair creation. I then discuss the main astrophysical applications --- situations with magnetar-strength fields (exceeding the quantum critical field of about 4 x 10^13 G): giant SGR flares and magnetically-powered central engines and jets of GRBs. Here, magnetic energy density is so high that its dissipation heats the plasma to MeV temperatures. Electron-positron pairs are then copiously produced, making the reconnection layer highly collisional and dressing it in a thick pair coat that traps radiation. The pressure is dominated by radiation and pairs. Yet, radiation diffusion across the layer may be faster than the global Alfv\'en transit time; then, radiative cooling governs the thermodynamics and reconnection becomes a radiative transfer problem, greatly affected by the ultra-strong magnetic field. This overall picture is very different from our traditional picture of reconnection and thus represents a new frontier in reconnection research.Comment: Accepted to Space Science Reviews (special issue on magnetic reconnection). Article is based on an invited review talk at the Yosemite-2010 Workshop on Magnetic Reconnection (Yosemite NP, CA, USA; February 8-12, 2010). 30 pages, no figure

Solving the Puzzles of the Decay of the Heaviest Known Proton-Emitting Nucleus Bi 185

Two long-standing puzzles in the decay of Bi185, the heaviest known proton-emitting nucleus are revisited. These are the nonobservation of the 9/2- state, which is the ground state of all heavier odd-A Bi isotopes, and the hindered nature of proton and α decays of its presumed 60-μs 1/2+ ground state. The Bi185 nucleus has now been studied with the Mo95(Nb93,3n) reaction in complementary experiments using the Fragment Mass Analyzer and Argonne Gas-Filled Analyzer at Argonne National Laboratory's ATLAS facility. The experiments have established the existence of two states in Bi185; the short-lived T1/2=2.8-1.0+2.3 μs, proton- and α-decaying ground state, and a 58(2)-μs γ-decaying isomer, the half-life of which was previously attributed to the ground state. The reassignment of the ground-state lifetime results in a proton-decay spectroscopic factor close to unity and represents the only known example of a ground-state proton decay to a daughter nucleus (Pb184) with a major shell closure. The data also demonstrate that the ordering of low- and high-spin states in Bi185 is reversed relative to the heavier odd-A Bi isotopes, with the intruder-based 1/2+ configuration becoming the ground, similar to the lightest At nuclides

Stress ocupacional e alteração do Estatuto da Carreira Docente português

Este estudo foi realizado com 1162 professores, tendo como objetivo analisar a experiência de stress e a síndrome de “burnout”, antes a após a alteração do Estatuto da Carreira Docente em Portugal. Assim, foram efetuadas duas avaliações em momentos temporais distintos, assumindo-se um plano transversal de recolha de dados (2004/2005, n=689 e 2008/2009, n=473). O protocolo de avaliação incluiu medidas de fontes de stress (Questionário de Stress nos Professores, Gomes, Silva, Mourisco, Mota, & Montenegro, 2006) e de “burnout” (Inventário de “Burnout” de Maslach – Versão para Professores, Maslach, Jackson, & Leiter, 1996; Maslach, Jackson, & Schwab, 1996, Adaptação de Gomes et al., 2006). Os resultados indicaram que a experiência de stress e de “burnout” aumentou entre as duas avaliações, verificando-se em 2008/2009 aumentos em áreas relacionadas com as pressões de tempo/excesso de trabalho e com o trabalho burocrático/administrativo e, inversamente, diminuições em áreas relacionadas com as diferentes capacidades e motivações dos alunos. Quanto à predição da síndrome de “burnout”, não se verificaram alterações substanciais nas variáveis preditoras nos dois momentos. Em síntese, os resultados indicaram aumentos nas exigências profissionais dos professores, mas não se pode afirmar que tal se deva às alterações do Estatuto da Carreira Docente uma vez que não observámos alterações no stress associado à carreira docente.(undefined

First identification of excited states in Ba 117 using the recoil- β -delayed proton tagging technique

Excited states have been observed for the first time in the neutron-deficient nucleus Ba117 using the recoil-decay tagging technique following the heavy-ion fusion-evaporation reaction Zn64(Ni58, 2p3n)Ba117. Prompt γ rays have been assigned to Ba117 through correlations with β-delayed protons following the decay of A=117 recoils. Through the analysis of the γ-γ coincidence relationships, a high-spin level scheme consisting of two bands has been established in Ba117. Based on the systematics of the level spacings in the neighboring barium isotopes, the two bands are proposed to have νh11/2[532]5/2- and νd5/2[413]5/2+ configurations, respectively. The observed band-crossing properties are interpreted in the framework of cranked shell model