1,267 research outputs found

    Pulsar Prospects for the Cherenkov Telescope Array

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    In the last few years, the Fermi-LAT telescope has discovered over a 100 pulsars at energies above 100 MeV, increasing the number of known gamma-ray pulsars by an order of magnitude. In parallel, imaging Cherenkov telescopes, such as MAGIC and VERITAS, have detected for the first time VHE pulsed gamma-rays from the Crab pulsar. Such detections have revealed that the Crab VHE spectrum follows a power-law up to at least 400 GeV, challenging most theoretical models, and opening wide possibilities of detecting more pulsars from the ground with the future Cherenkov Telescope Array (CTA). In this contribution, we study the capabilities of CTA for detecting Fermi pulsars. For this, we extrapolate their spectra with "Crab-like" power-law tails in the VHE range, as suggested by the latest MAGIC and VERITAS results.Comment: 4 pages, 3 figures. In Proceedings of the 2012 Heidelberg Symposium on High Energy Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184

    Lifestyle Influence on the Content of Copper, Zinc and Rubidium in Wild Mushrooms

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    The concentration of 18 trace elements in several species of fungi (arranged in three groups: ectomycorrhizae, saprobes, and epiphytes) has been determined. The measurements were made using the methodology of X-ray fluorescence. Higher contents of Cu and Rb (with statistical support) have been found in the ectomycorrhizal species. The Zn content reached higher concentrations in the saprophytic species. According to the normality test and the search for outliers, the species Clitocybe maxima and Suillus bellini accumulate large amounts of Cu and Rb, respectively, so that both can be named as “outliers.” The leftwards displacement of the density curves and their nonnormality are attributed to the presence of these two species, which exhibit hyperaccumulation skills for Cu and Rb, respectively. Regarding Zn absorption, no particular species were classified as outlier; therefore it can be assumed that the observed differences between the different groups of fungi are due to differences in their nutritional physiology

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    Procesos de instauración y consolidación democrática en el África de los '90

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    Grapevine leaf uptake of mineral elements influenced by sugar foam amendment of an acidic soil

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    The use of sugar foam (industrial waste from sugar beet extraction) as an acidic soil (raña) liming agent has been studied in a singular winegrowing region. The contents of the major elements (Al, Ca, Fe, K, Na, Mg, S, Si) and trace elements (As, Ba, Ce, Co, Cr, Cs, Cu, Ga, Hf, La, Mo, Nb, Nd, Ni, Pb, Rb, Sc, Sn, Sr, Ta, Th, U, V, W, Y, Zn, Zr) in the original soil, the amended soil and in grapevine leaves has been measured by X-ray fluorescence. The addition of sugar foam modified the agronomic properties of the original soil. The amendment caused a slight increase in major elements (Ca, 10.4 g·kg-1; Mg, 1.9 g·kg-1 and K, 12.9 g·kg-1) and decreased Al (from 62 to 57.8 g·kg-1) and Fe (from 41.2 to 26.5 g·kg-1) content. Regarding trace elements, there was an increase in levels of Ba, Rb and Sr in the amended soil in comparison to the original soil. The major elements that accumulated in the vine leaf were Ca, Mg and S (Biological Absorption Coefficient, BAC, greater than 1). As for trace elements in leaf, Ba and Sr had a "medium" BAC (0.27 and 0.8, respectively) whereas Rb had a "slight"value (0.08). It is worth noting that the bioaccumulation rate of Zn was greater than 1. The use of sugar foam as a liming agent did not have a negative effect on the absorption of major and trace elements in vine leaves and led to improved BAC values for essential elements in the grapevine. The treatment did not increase the amount of trace elements in the soil above the reference levels for the region.

    Design of the Front End Electronics for the Infrared Camera of JEM-EUSO, and manufacturing and verification of the prototype model

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    The Japanese Experiment Module (JEM) Extreme Universe Space Observatory (EUSO) will be launched and attached to the Japanese module of the International Space Station (ISS). Its aim is to observe UV photon tracks produced by ultra-high energy cosmic rays developing in the atmosphere and producing extensive air showers. The key element of the instrument is a very wide-field, very fast, large-lense telescope that can detect extreme energy particles with energy above 101910^{19} eV. The Atmospheric Monitoring System (AMS), comprising, among others, the Infrared Camera (IRCAM), which is the Spanish contribution, plays a fundamental role in the understanding of the atmospheric conditions in the Field of View (FoV) of the telescope. It is used to detect the temperature of clouds and to obtain the cloud coverage and cloud top altitude during the observation period of the JEM-EUSO main instrument. SENER is responsible for the preliminary design of the Front End Electronics (FEE) of the Infrared Camera, based on an uncooled microbolometer, and the manufacturing and verification of the prototype model. This paper describes the flight design drivers and key factors to achieve the target features, namely, detector biasing with electrical noise better than 100μ100 \muV from 11 Hz to 1010 MHz, temperature control of the microbolometer, from 1010^{\circ}C to 4040^{\circ}C with stability better than 1010 mK over 4.84.8 hours, low noise high bandwidth amplifier adaptation of the microbolometer output to differential input before analog to digital conversion, housekeeping generation, microbolometer control, and image accumulation for noise reduction

    Spectroscopy and Orbital Analysis of Bright Bolides Observed over the Iberian Peninsula from 2010 to 2012

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    We present the analysis of the atmospheric trajectory and orbital data of four bright bolides observed over Spain, one of which is a potential meteorite dropping event. Their absolute magnitude ranges from -10 to -11. Two of these are of sporadic origin, although a Geminid and a kappa-Cygnid fireball are also considered. These events were recorded in the framework of the continuous fireball monitoring and spectroscopy campaigns developed by the SPanish Meteor Network (SPMN) between 2010 and 2012. The tensile strength of the parent meteoroids is estimated and the abundances of the main rock-forming elements in these particles are calculated from the emission spectrum obtained for three of these events. This analysis revealed a chondritic nature for these meteoroids.Comment: Manuscript in press in Monthly Notices of the Royal Astronomical Societ
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