4,920 research outputs found
New data processing technologies at LHC: From Grid to Cloud Computing and beyond
Since a few years the LHC experiments at CERN are successfully using the Grid Computing Technologies for their distributed data processing activities, on a global scale. Recently, the experience gained with the current systems allowed the design of the future Computing Models, involving new technologies like Could Computing, virtualization and high performance distributed database access. In this paper we shall describe the new computational technologies of the LHC experiments at CERN, comparing them with the current models, in terms of features
and performance
SAX J1808.4-3658, an accreting millisecond pulsar shining in gamma rays?
We report the detection of a possible gamma-ray counterpart of the accreting
millisecond pulsar SAX J1808.4-3658. The analysis of ~6 years of data from the
Large Area Telescope on board the Fermi Gamma-ray Space Telescope (Fermi-LAT)
within a region of 15deg radius around the position of the pulsar reveals a
point gamma-ray source detected at a significance of ~6 sigma (Test Statistic
TS = 32), with position compatible with that of SAX J1808.4-3658 within 95%
Confidence Level. The energy flux in the energy range between 0.6 GeV and 10
GeV amounts to (2.1 +- 0.5) x 10-12 erg cm-2 s-1 and the spectrum is
well-represented by a power-law function with photon index 2.1 +- 0.1. We
searched for significant variation of the flux at the spin frequency of the
pulsar and for orbital modulation, taking into account the trials due to the
uncertainties in the position, the orbital motion of the pulsar and the
intrinsic evolution of the pulsar spin. No significant deviation from a
constant flux at any time scale was found, preventing a firm identification via
time variability. Nonetheless, the association of the LAT source as the
gamma-ray counterpart of SAX J1808.4-3658 would match the emission expected
from the millisecond pulsar, if it switches on as a rotation-powered source
during X-ray quiescence.Comment: 8 pages, 4 figures, accepted by MNRA
Agricultural support policies and GHG emissions from agriculture in Latin America: relationships and policy implications for climate change
Domestic support policies for farmers and agriculture, through their price effect, have been deemed potentially environmentally harmful; for example, in developing countries, agricultural prices have been set- below the world market prices, aiming to secure low retail prices for urban consumers. This practice has lowered producer prices, and thereby prevented farmers from adopting ecofriendly production techniques. This study uses policy data —market price support (MPS) and general service support estimates (GSSE) as shares of total support estimate (TSE)— and greenhouse gases (GHG) data for main crops and livestock sectors in 18 Latin-American countries and it applies cluster analysis to construct a typology that highlights patterns between policy incentives for agricultural crops and activities and GHG emissions. The results suggest that an increase in the TSE and/or MPS comprising a large share of the TSE leads to an increase in GHGs. Conversely, GHGs fall when GSSE comprise a larger share of the TSE. Las políticas internas de apoyo a los agricultores y la agricultura, a través de su efecto sobre los precios, pueden ser potencialmente dañinas para el medio ambiente; por ejemplo, en los países en desarrollo, los precios agrícolas se han fijado por debajo de los precios del mercado mundial, con el objetivo de asegurar precios minoristas bajos para los consumidores urbanos. Esta práctica reduce bajar los precios al productor y, por lo tanto, es un obstáculo que los agricultores adopten técnicas de producción ecológicas. En este estudio, se utilizan datos de políticas —soporte de precios de mercado y estimaciones de apoyo a los servicios generales como porcentajes de la estimación del apoyo total— y datos de gases de efecto invernadero (GEI) para los principales cultivos y sectores ganaderos en 18 países latinoamericanos, además de aplicarse análisis de conglomerados para construir una tipología en la que se destacan patrones entre políticas de incentivos para cultivos y actividades agrícolas y emisiones de GEI. Los resultados sugieren que un aumento en la estimación del apoyo total y/o en el soporte de precios de mercado, que comprende una gran parte, conduce a un incremento en los GEI. Por el contrario, estos caen cuando las estimaciones de apoyo a los servicios generales comprenden una mayor parte de la estimación del apoyo total.
Pharmacokinetics and antinociceptive effects of tramadol and its metabolite O-desmethyltramadol following intravenous administration in sheep
Although sheep are widely used as an experimental model for various surgical procedures there is a paucity of data on the pharmacokinetics and efficacy of analgesic drugs in this species. The aims of this study were to investigate the pharmacokinetics of intravenously (IV) administered tramadol and its active metabolite O-desmethyltramadol (M1) and to assess the mechanical antinociceptive effects in sheep. In a prospective, randomized, blinded study, six healthy adult sheep were given 4 and 6\u2009mg/kg tramadol and saline IV in a cross-over design with a 2-week wash-out period. At predetermined time points blood samples were collected and physiological parameters and mechanical nociceptive threshold (MNT) values were recorded. The analytical determination of tramadol and M1 was performed using high performance liquid chromatography. Pharmacokinetic parameters fitted a two- and a non-compartmental model for tramadol and M1, respectively. Normally distributed data were analysed by a repeated mixed linear model. Plasma concentration vs. time profiles of tramadol and M1 were similar after the two doses. Tramadol and M1 plasma levels decreased rapidly in the systemic circulation, with both undetectable after 6\u2009h following drug administration. Physiological parameters did not differ between groups; MNT values were not statistically significant between groups at any time point. It was concluded that although tramadol and M1 concentrations in plasma were above the human minimum analgesic concentration after both treatments, no mechanical antinociceptive effects of tramadol were reported. Further studies are warranted to assess the analgesic efficacy of tramadol in sheep
Palladium iodide-catalyzed selective carbonylative double cyclization of 4-(2-aminophenyl)-3-yn-1-ols to dihydrofuroquinolinone derivatives
The PdI2/KI‐catalyzed oxidative carbonylation of 4‐(2‐aminophenyl)‐3‐yn‐1‐ols, bearing two potential nucleophilic groups in suitable position selectively leads to dihydrofuroquinolinone derivatives in fair to high yields (60%—89%) and excellent turnover numbers (180—267 mol of product per mol of Pd) over 19 examples, through a mechanistic pathway involving initial O‐cyclization followed by N‐cyclocarbonylation. In such process, the selective catalytic construction of two rings and three new bonds is achieved in one synthetic step to afford high value added fused heterocyclic structures starting from readily available materials
Sobre la presencia de Azolla filiculoides Lam. en España
A zolla filiculoides Lam. is reported as new to the Flora of Spain.A zolla filiculoides Lam. se cita por primera vez para España
Strategies for improving early detection and diagnosis of neovascular age-related macular degeneration
Treatment of the neovascular form of age-related macular degeneration (AMD) has been revolutionized by the introduction of such agents as ranibizumab, bevacizumab, and aflibercept. As a result, the incidence of legal blindness occurring secondary to AMD has fallen dramatically in recent years in many countries. While these agents have undoubtedly been successful in reducing visual impairment and blindness, patients with neovascular AMD typically lose some vision over time, and often lose the ability to read, drive, or perform other important activities of daily living. Efforts are therefore under way to develop strategies that allow for earlier detection and treatment of this disease. In this review, we begin by providing an overview of the rationale for, and the benefits of, early detection and treatment of neovascular AMD. To achieve this, we begin by providing an overview of the pathophysiology and natural history of choroidal neovascularization, before reviewing the evidence from both clinical trials and "real-world" outcome studies. We continue by highlighting an area that is often overlooked: the importance of patient education and awareness for early AMD detection. We conclude the review by reviewing an array of both established and emerging technologies for early detection of choroidal neovascularization, ranging from Amsler chart testing, to hyperacuity testing, to advanced imaging techniques, such as optical coherence tomography
An XMM-Newton and INTEGRAL view on the hard state of EXO 1745-248 during its 2015 outburst
CONTEXT - Transient low-mass X-ray binaries (LMXBs) often show outbursts
lasting typically a few-weeks and characterized by a high X-ray luminosity
( erg/sec), while for most of the time they are
found in X-ray quiescence ( erg/sec). EXO 1745-248
is one of them. AIMS - The broad-band coverage, and the sensitivity of
instrument on board of {\xmm} and {\igr}, offers the opportunity to
characterize the hard X-ray spectrum during {\exo} outburst. METHODS - In this
paper we report on quasi-simultaneous {\xmm} and {\igr} observations of the
X-ray transient {\exo} located in the globular cluster Terzan 5, performed ten
days after the beginning of the outburst (on 2015 March 16th) shown by the
source between March and June 2015. The source was caught in a hard state,
emitting a 0.8-100 keV luminosity of ~{\lumcgs}. RESULTS - The
spectral continuum was dominated by thermal Comptonization of seed photons with
temperature keV, by a cloud with moderate optical depth
and electron temperature keV. A weaker soft
thermal component at temperature --0.7 keV and compatible
with a fraction of the neutron star radius was also detected. A rich emission
line spectrum was observed by the EPIC-pn on-board {\xmm}; features at energies
compatible with K- transitions of ionized sulfur, argon, calcium and
iron were detected, with a broadness compatible with either thermal Compton
broadening or Doppler broadening in the inner parts of an accretion disk
truncated at gravitational radii from the neutron star. Strikingly, at
least one narrow emission line ascribed to neutral or mildly ionized iron is
needed to model the prominent emission complex detected between 5.5 and 7.5
keV. (Abridged)Comment: 14 pages, 6 figure, 2 tables. Accepted for publication on A&A
(21/03/2017
Neutron star radius-To-mass ratio from partial accretion disk occultation as measured through fe kα line profiles
We present a new method to measure the radius-To-mass ratio (R/M) of weakly magnetic, disk-Accreting neutron stars by exploiting the occultation of parts of the inner disk by the star itself. This occultation imprints characteristic features on the X-ray line profile that are unique and are expected to be present in low-mass X-ray binary systems seen under inclinations higher than ∼65°. We analyze a Nuclear Spectroscopic Telescope Array observation of a good candidate system, 4U 1636-53, and find that X-ray spectra from current instrumentation are unlikely to single out the occultation features owing to insufficient signal-To-noise. Based on an extensive set of simulations we show that large-Area X-ray detectors of the future generation could measure R/M to ∼2 ÷ 3% precision over a range of inclinations. Such is the precision in radius determination required to derive tight constraints on the equation of state of ultradense matter and it represents the goal that other methods also aim to achieve in the future
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