681 research outputs found
Impact of multiple radar reflectivity data assimilation on the numerical simulation of a flash flood event during the HyMeX campaign
An analysis to evaluate the impact of multiple radar reflectivity data with a three-dimensional variational (3-D-Var) assimilation system on a heavy precipitation event is presented. The main goal is to build a regionally tuned numerical prediction model and a decision-support system for environmental civil protection services and demonstrate it in the central Italian regions, distinguishing which type of observations, conventional and not (or a combination of them), is more effective in improving the accuracy of the forecasted rainfall. In that respect, during the first special observation period (SOP1) of HyMeX (Hydrological cycle in the Mediterranean Experiment) campaign several intensive observing periods (IOPs) were launched and nine of which occurred in Italy. Among them, IOP4 is chosen for this study because of its low predictability regarding the exact location and amount of precipitation. This event hit central Italy on 14 September 2012 producing heavy precipitation and causing several cases of damage to buildings, infrastructure, and roads. Reflectivity data taken from three C-band Doppler radars running operationally during the event are assimilated using the 3-D-Var technique to improve high-resolution initial conditions. In order to evaluate the impact of the assimilation procedure at different horizontal resolutions and to assess the impact of assimilating reflectivity data from multiple radars, several experiments using the Weather Research and Forecasting (WRF) model are performed. Finally, traditional verification scores such as accuracy, equitable threat score, false alarm ratio, and frequency bias - interpreted by analysing their uncertainty through bootstrap confidence intervals (CIs) - are used to objectively compare the experiments, using rain gauge data as a benchmark
Characterization of Salmonella Occurring at High Prevalence in a Population of the Land Iguana Conolophus subcristatus in Galapagos Islands, Ecuador
The aim of the study was to elucidate the association between the zoonotic pathogen Salmonella and a population of land iguana, Colonophus subcristatus, endemic to GalĂĄpagos Islands in Ecuador. We assessed the presence of Salmonella subspecies and serovars and estimated the prevalence of the pathogen in that population. Additionally, we investigated the genetic relatedness among isolates and serovars utilising pulsed field gel electrophoresis (PFGE) on XbaI-digested DNA and determined the antimicrobial susceptibility to a panel of antimicrobials. The study was carried out by sampling cloacal swabs from animals (nâ=â63) in their natural environment on in the island of Santa Cruz. A high prevalence (62/63, 98.4%) was observed with heterogeneity of Salmonella subspecies and serovars, all known to be associated with reptiles and with reptile-associated salomonellosis in humans. Serotyping revealed 14 different serovars among four Salmonella enterica subspecies: S. enterica subsp. enterica (nâ=â48), S. enterica subsp. salamae (nâ=â2), S. enterica subsp. diarizonae (nâ=â1), and S. enterica subsp. houtenae (nâ=â7). Four serovars were predominant: S. Poona (nâ=â18), S. Pomona (nâ=â10), S. Abaetetuba (nâ=â8), and S. Newport (nâ=â5). The S. Poona isolates revealed nine unique XbaI PFGE patterns, with 15 isolates showing a similarity of 70%. Nine S. Pomona isolates had a similarity of 84%. One main cluster with seven (88%) indistinguishable isolates of S. Abaetetuba was observed. All the Salmonella isolates were pan-susceptible to antimicrobials representative of the most relevant therapeutic classes. The high prevalence and absence of clinical signs suggest a natural interaction of the different Salmonella serovars with the host species. The interaction may have been established before any possible exposure of the iguanas and the biocenosis to direct or indirect environmental factors influenced by the use of antimicrobials in agriculture, in human medicine or in veterinary medicine
Analyzing Creativity in the Light of Social Practice Theory
In this work, starting from the social practice theory, we identified two kinds of creativity: a situational creativity that takes place when, starting from a defined situation, a social practice is played; and a creativity of habit that concerns the agents' capacity for generating new practices from habit when the situation is not defined or is unexpected. To test this hypothesis, the Torrance Test of Creative Thinking (Verbal Form A) was analyzed in the light of praxeology, and the results are analyzed in a computational creativity perspective
A New Monte Carlo Method for Time-Dependent Neutrino Radiation Transport
Monte Carlo approaches to radiation transport have several attractive properties compared to deterministic
methods. These include simplicity of implementation, high accuracy, and good parallel scaling. Moreover,
Monte Carlo methods can handle complicated geometries and are relatively easy to extend to multiple spatial
dimensions, which makes them particularly interesting in modeling complex multi-dimensional astrophysical
phenomena such as core-collapse supernovae. The aim of this paper is to explore Monte Carlo methods for
modeling neutrino transport in core-collapse supernovae. We generalize the implicit Monte Carlo photon transport
scheme of Fleck & Cummings and gray discrete-diffusion scheme of Densmore et al. to energy-, time-,
and velocity-dependent neutrino transport. Using our 1D spherically-symmetric implementation, we show that,
similar to the photon transport case, the implicit scheme enables significantly larger timesteps compared with
explicit time discretization, without sacrificing accuracy, while the discrete-diffusion method leads to significant
speed-ups at high optical depth. Our results suggest that a combination of spectral, velocity-dependent,
implicit Monte Carlo and discrete-diffusion Monte Carlo methods represents an attractive approach for use in
neutrino radiation-hydrodynamics simulations of core-collapse supernovae. Our velocity-dependent scheme
can easily be adapted to photon transport
Agricultural Production and Externalities Simulator (APES) prototype to be used in Prototype 1 of SEAMLESS-IF
Production Economics,
Library of model components for process simulation relevant to production activities, Prototype 1 versions
Production Economics,
Demonstrating the validity of the Video Game Functional Assessment-Revised (VGFA-R)
Problematic video play has been well documented over the course of the last decade. So much so the DSM-5 (APA, 2013) has included problematic video gaming as disorder categorized as Internet Gaming Disorder. The field of applied behavior analysis has been utilizing functional assessments for the last 30 years and has showed evidence of effective results across different populations and environments. Therefore, the purpose of this investigation (comprising three studies) was to validate an indirect functional assessment entitled the Video Game Functional Assessment-Revised (VGFA-R). Using academic experts in the field of video game addiction and applied behavioral analysis (n=6), the first study examined the content validity of the VGFA-R and was able to demonstrate the assessment exceeded the criterion for an established assessment. A second study comprising a survey of 467 gamers examined the factorability by using a confirmatory factor analysis, and found that VGFA-R had an overall variance above .60. Within the third laboratory-based study using gamers (n=11), the VGFA-R was examined for construct validity and found the VGFA-R was able to predict 85% of the appropriate function of behavior. Implications of the study are discussed along with the strengths and limitations of the study and future research directions
Quantum vortices in systems obeying a generalized exclusion principle
The paper deals with a planar particle system obeying a generalized exclusion
principle (EP) and governed, in the mean field approximation, by a nonlinear
Schroedinger equation. We show that the EP involves a mathematically simple and
physically transparent mechanism, which allows the genesis of quantum vortices
in the system. We obtain in a closed form the shape of the vortices and
investigate its main physical properties.
PACS numbers: 03.65.-w, 03.65.Ge, 05.45.YvComment: 7 pages, 4 figure
Weak Lensing by Galaxies in Groups and Clusters: I.--Theoretical Expectations
Galaxy-galaxy lensing is rapidly becoming one of the most promising means to
accurately measure the average relation between galaxy properties and halo
mass. In order to obtain a signal of sufficient signal-to-noise, one needs to
stack many lens galaxies according to their property of interest, such as
luminosity or stellar mass. Since such a stack consists of both central and
satellite galaxies, which contribute very different lensing signals, the
resulting shear measurements can be difficult to interpret. In the past,
galaxy-galaxy lensing studies have either completely ignored this problem, have
applied rough isolation criteria in an attempt to preferentially select
`central' galaxies, or have tried to model the contribution of satellites
explicitely. However, if one is able to {\it a priori} split the galaxy
population in central and satellite galaxies, one can measure their lensing
signals separately. This not only allows a much cleaner measurement of the
relation between halo mass and their galaxy populations, but also allows a
direct measurement of the sub-halo masses around satellite galaxies. In this
paper, we use a realistic mock galaxy redshift survey to show that galaxy
groups, properly selected from large galaxy surveys, can be used to accurately
split the galaxy population in centrals and satellites. Stacking the resulting
centrals according to their group mass, estimated from the total group
luminosity, allows a remarkably accurate recovery of the masses and density
profiles of their host haloes. In addition, stacking the corresponding
satellite galaxies according to their projected distance from the group center
yields a lensing signal that can be used to accurate measure the masses of both
sub-haloes and host haloes. (Abridged)Comment: 16 pages, 10 figures, Accepted for publication in MNRA
The velocity dispersion and mass function of the outer halo globular cluster Palomar 4
We obtained precise line-of-sight radial velocities of 23 member stars of the
remote halo globular cluster Palomar 4 (Pal 4) using the High Resolution
Echelle Spectrograph (HIRES) at the Keck I telescope. We also measured the mass
function of the cluster down to a limiting magnitude of V~28 mag using archival
HST/WFPC2 imaging. We derived the cluster's surface brightness profile based on
the WFPC2 data and on broad-band imaging with the Low-Resolution Imaging
Spectrometer (LRIS) at the Keck II telescope. We find a mean cluster velocity
of 72.55+/-0.22 km/s and a velocity dispersion of 0.87+/-0.18 km/s. The global
mass function of the cluster, in the mass range 0.55<=M<=0.85 M_solar, is
shallower than a Kroupa mass function and the cluster is significantly depleted
in low-mass stars in its center compared to its outskirts. Since the relaxation
time of Pal 4 is of the order of a Hubble time, this points to primordial mass
segregation in this cluster. Extrapolating the measured mass function towards
lower-mass stars and including the contribution of compact remnants, we derive
a total cluster mass of 29800 M_solar. For this mass, the measured velocity
dispersion is consistent with the expectations of Newtonian dynamics and below
the prediction of Modified Newtonian Dynamics (MOND). Pal 4 adds to the growing
body of evidence that the dynamics of star clusters in the outer Galactic halo
can hardly be explained by MOND.Comment: 17 pages, accepted for publication in MNRAS; Fig. 8 surface
brightness/density data at github.com/matthiasjfrank/pal4_surface_brightnes
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