2,335 research outputs found
ALICE experience with GEANT4
Since its release in 1999, the LHC experiments have been evaluating GEANT4 in
view of adopting it as a replacement for the obsolescent GEANT3 transport
MonteCarlo. The ALICE collaboration has decided to perform a detailed physics
validation of elementary hadronic processes against experimental data already
used in international benchmarks. In one test, proton interactions on different
nuclear targets have been simulated, and the distribution of outgoing particles
has been compared to data. In a second test, penetration of quasi-monoenergetic
low energy neutrons through a thick shielding has been simulated and again
compared to experimental data. In parallel, an effort has been put on the
integration of GEANT4 in the AliRoot framework. An overview of the present
status of ALICE GEANT4 simulation and the remaining problems will be presented.
This document will describe in detail the results of these tests, together with
the improvements that the GEANT4 team has made to the program as a result of
the feedback received from the ALICE collaboration. We will also describe the
remaining problems that have been communicated to GEANT4 but not yet addressed.Comment: 8 pages, 12 figures, for the CHEP03 conference proceeding
The CMS experiment workflows on StoRM based storage at Tier-1 and Tier-2 centers
Approaching LHC data taking, the CMS experiment is deploying, commissioning and operating the building tools of its grid-based computing infrastructure. The commissioning program includes testing, deployment and operation of various storage solutions to support the computing workflows of the experiment. Recently, some of the Tier-1 and Tier-2 centers supporting the collaboration have started to deploy StoRM based storage systems. These are POSIX-based disk storage systems on top of which StoRM implements the Storage Resource Manager (SRM) version 2 interface allowing for a standard-based access from the Grid. In this notes we briefly describe the experience so far achieved at the CNAF Tier-1 center and at the IFCA Tier-2 center
Chemical abundances of late-type pre-main sequence stars in the -Orionis cluster
The young -Orionis cluster is an important location for understanding
the formation and evolution of stars, brown dwarfs, and planetary-mass objects.
Its metallicity, although being a fundamental parameter, has not been well
determined yet. We present the first determination of the metallicity of nine
young late-type stars in -Orionis. Using the optical and near-infrared
broadband photometry available in the literature we derive the effective
temperatures for these nine cluster stars, which lie in the interval 4300--6500
K (1--3 \Msuno). These parameters are employed to compute a grid of synthetic
spectra based on the code MOOG and Kurucz model atmospheres. We employ a
-minimization procedure to derive the stellar surface gravity and
atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical
spectroscopy taken with WYFFOS+AF2 at at the William Herschel Telescope
(). The average metallicity of the
-Orionis cluster is [Fe/H] (random and
systematic errors). The abundances of the other elements, except lithium, seem
to be consistent with solar values. Lithium abundances are in agreement with
the "cosmic" Li abundance, except for two stars which show a in the range 3.6--3.7 (although almost consistent within
the error bars). There are also other two stars with . We derived an average radial velocity of the
-Orionis cluster of km/s. The -Orionis metallicity is
roughly solar.Comment: Accepted for publication in Astronomy and Astrophysic
Coastal macrophytes contribute to the long term geomorphological stability of Cadiz Bay
Charla presentada en el 2015 Aquatic Sciences Meeting. Aquatic Sciences: Global And Regional Perspectives — North Meets South (http://sgmeet.com/aslo/granada2015)In the Eastern Gulf of Cadiz, terrestrial sediments are mainly supplied by the large Guadalquivir and smaller Guadalete rivers, both of which are subject to substantial man-made interventions. These rivers are the main sediment source to Cadiz Bay; a shallow, meso-tidal bay with high subtidal macrophyte coverage and extensive salt marshes that appears to act as an effective filter, retaining fine material and ensuring accretion rates that match sea-level rise. Field observations suggest that the relative importance of the different mechanisms by which macrophyte canopies promote accretion is related to their species-specific biometric properties and zonation. Overall, we argue that the key mechanism which enhances long-term accretion in the bay is related to the reduction of erosive forces on the sediment bed cause by the interaction of plant canopies with local hydrodynamics, particularly during high wind events. Considering the importance of coastal macrophytes for long-term accretion, we briefly discuss how different local and regional management strategies in relation to IPCC climate change predictions may influence terrestrial derived-sediment dynamics.EU FP7-SPACE-2013: FAST - GA n.607131, Junta Andalucia: P07-RNM-2516, P09-RNM-4853, PR11-RNM-7722,MECD: CTM2008-00012/MAR, Schure-Beijerinck-Popping Fund: SBP/JK/2007-32), E.U. MarinERA
Project MedEX: CTM2008-04036-E/MAR) y PERSEUS (FP7-287600)Charla en formato pd
Exercise increases the dynamics of diurnal cortisol secretion and executive functionin people wiht MCI
Summary:
Regular physical activity is protective against and beneficial for Mild Cognitive Impairment (MCI), dementia, and Alzheimer´s disease. The mechanisms underlying these benefits remain unknown although it has been suggested that exercise-induced changes in the circadian pattern of cortisol secretion may be implicated. Fitness, salivary cortisol levels (0 and 30 mins post awakening, midday, 5pm and 9pm) and cognitive function were determined in a group of amnestic MCI patients (n=39) before and after a three-month exercise program (n=19) or usual care (n=20). At base fitness measures were positively correlated with peak levels of cortisol and a greater fall in cortisol concentration from peak levels to midday. The exercise intervention successfully increased fitness and resulted in a greater fall in cortisol concentration from peak to midday, compared to the control group. The exercise intervention enhanced indices of executive function, although memory, mood, and functionality were not affected
Fuzzy-based forest fire prevention and detection by wireless sensor networks
Forest fires may cause considerable damages both in ecosystems and lives.
This proposal describes the application of Internet of Things and wireless
sensor networks jointly with multi-hop routing through a real time and dynamic
monitoring system for forest fire prevention. It is based on gathering and
analyzing information related to meteorological conditions, concentrations of
polluting gases and oxygen level around particular interesting forest areas.
Unusual measurements of these environmental variables may help to prevent
wildfire incidents and make their detection more efficient. A forest fire risk
controller based on fuzzy logic has been implemented in order to activate
environmental risk alerts through a Web service and a mobile application. For
this purpose, security mechanisms have been proposed for ensuring integrity and
confidentiality in the transmission of measured environmental information.
Lamport's signature and a block cipher algorithm are used to achieve this
objective
Electron- versus neutrino-nucleus scattering
We illustrate the connection between electron and neutrino scattering off
nuclei and show how the former process can be used to constrain the description
of the latter. After reviewing some of the nuclear models commonly used to
study lepton-nucleus reactions, we describe in detail the SuSAv2 model and show
how its predictions compare with the available electron- and
neutrino-scattering data over the kinematical range going from the
quasi-elastic peak to pion-production and highly inelastic scattering.Comment: Shortened version, 71 pages, review article, 52 figure
The nuclear and extended mid-infrared emission of Seyfert galaxies
We present subarcsecond resolution mid-infrared (MIR) images obtained with
8-10 m-class ground-based telescopes of a complete volume-limited (DL<40 Mpc)
sample of 24 Seyfert galaxies selected from the Swift/BAT nine month catalog.
We use those MIR images to study the nuclear and circumnuclear emission of the
galaxies. Using different methods to classify the MIR morphologies on scales of
~400 pc, we find that the majority of the galaxies (75-83%) are extended or
possibly extended and 17-25% are point-like. This extended emission is compact
and it has low surface brightness compared with the nuclear emission, and it
represents, on average, ~30% of the total MIR emission of the galaxies in the
sample. We find that the galaxies whose circumnuclear MIR emission is dominated
by star formation show more extended emission (650+-700 pc) than AGN-dominated
systems (300+-100 pc). In general, the galaxies with point-like MIR
morphologies are face-on or moderately inclined (b/a~0.4-1.0), and we do not
find significant differences between the morphologies of Sy1 and Sy2. We used
the nuclear and circumnuclear fluxes to investigate their correlation with
different AGN and SF activity indicators. We find that the nuclear MIR emission
(the inner ~70 pc) is strongly correlated with the X-ray emission (the harder
the X-rays the better the correlation) and with the [O IV] lambda 25.89 micron
emission line, indicating that it is AGN-dominated. We find the same results,
although with more scatter, for the circumnuclear emission, which indicates
that the AGN dominates the MIR emission in the inner ~400 pc of the galaxies,
with some contribution from star formation.Comment: 27 pages, 12 figures, accepted by MNRA
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