10,468 research outputs found
Interacting dark sector with variable vacuum energy
We examine a cosmological scenario where dark matter is coupled to a variable
vacuum energy while baryons and photons are two decoupled components for a
spatially flat Friedmann-Robertson-Walker spacetime. We apply the
method to the updated observational Hubble data for constraining the
cosmological parameters and analyze the amount of dark energy in the radiation
era. We show that our model fulfills the severe bound of at the level, so it is consistent with the recent
analysis that includes cosmic microwave background anisotropy measurements from
the Planck survey, the Atacama Cosmology Telescope, and the South Pole
Telescope along with the future constraints achievable by the Euclid and CMBPol
experiments, and fulfills the stringent bound at the level in the big-bang nucleosynthesis epoch.Comment: 5 pages,3 figures, 2 tables.
(http://prd.aps.org/abstract/PRD/v88/i8/e087301
Symmetry limit properties of a priori mixing amplitudes for non-leptonic and weak radiative decays of hyperons
We show that the so-called parity-conserving amplitudes predicted in the a
priori mixing scheme for non-leptonic and weak radiative decays of hyperons
vanish in the strong-flavor symmetry limit
Mirror matter admixtures in K_S to gamma gamma
The latest measurement of the K_S to gamma gamma branching ratio clearly
shows an enhancement over the current theoretical prediction. As in other K and
B meson decays, this invites to consider the possibility of the contribution of
new physics. We study a particular form of the latter, which may be referred to
as manifest mirror symmetry. The experimental data are described using
previously determined values for the mixing angles of the admixtures of mirror
matter in ordinary hadrons and by assuming that for pi^0, eta, eta', the mirror
decay amplitudes have the same magnitudes as their ordinary counterparts
The complex structure of HH 110 as revealed from Integral Field Spectroscopy
HH 110 is a rather peculiar Herbig-Haro object in Orion that originates due
to the deflection of another jet (HH 270) by a dense molecular clump, instead
of being directly ejected from a young stellar object. Here we present new
results on the kinematics and physical conditions of HH 110 based on Integral
Field Spectroscopy. The 3D spectral data cover the whole outflow extent (~4.5
arcmin, ~0.6 pc at a distance of 460 pc) in the spectral range 6500-7000 \AA.
We built emission-line intensity maps of H, [NII] and [SII] and of
their radial velocity channels. Furthermore, we analysed the spatial
distribution of the excitation and electron density from [NII]/H,
[SII]/H, and [SII] 6716/6731 integrated line-ratio maps, as well as
their behaviour as a function of velocity, from line-ratio channel maps. Our
results fully reproduce the morphology and kinematics obtained from previous
imaging and long-slit data. In addition, the IFS data revealed, for the first
time, the complex spatial distribution of the physical conditions (excitation
and density) in the whole jet, and their behaviour as a function of the
kinematics. The results here derived give further support to the more recent
model simulations that involve deflection of a pulsed jet propagating in an
inhomogeneous ambient medium. The IFS data give richer information than that
provided by current model simulations or laboratory jet experiments. Hence,
they could provide valuable clues to constrain the space parameters in future
theoretical works.Comment: 12 pages, 15 figures Accepted in MNRA
A Mathematical Model to Study the Meningococcal Meningitis
AbstractThe main goal of this work is to introduce a novel mathematical model to study the spreading of meningococcal meningitis. Specifically, it is a discrete mathematical model based on cellular automata where the population is divided in five classes: sus- ceptible, asymptomatic infected, infected with symptoms, carriers, recovered and died. It catches the individual characteristics of people in order to give a prediction of both the individual behavior, and whole evolution of population
MS-222 toxicity in juvenile seabream correlates with diurnal activity, as measured by a novel video-tracking method
©2010. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
This document is the Accepted version of a Published Work that appeared in final form in Aquaculture. To access the final edited and published work see
https://doi.org/10.1016/j.aquaculture.2010.06.028Fish are frequently exposed to anaesthetics since their use is necessary in several
aquaculture procedures. The aim of this study was to investigate the existence of day night differences in toxicity and effectiveness of a common fish anaesthetic (MS-222)
in juvenile gilthead seabream (Sparus aurata), determining the induction time of
anaesthesia and subsequent recovery by a novel video-recording system. Our results
showed that MS-222 toxicity was significantly higher at ML (mid-light) (LC50=85.5
mg/L) than at MD (mid-darkness) (LC50=107.6 mg/L) (trimmed Spearman-Karber
method). In addition, when fish were exposed to a sublethal but effective MS-222
concentration (65 mg/L), 7 min passed before 50% a reduction in swimming activity
was observed at ML compared to the 9 min required at MD. As regards recovery, fish
showed activity levels similar to basal levels 10 min after MS-222 removal at ML, but
only 6 min at MD. These results indicated that both toxicity and effectiveness were
higher during the day than at night, coinciding with the diurnal activity pattern
displayed by seabream, which should be taken into account when designing and
applying daily protocols for anaesthesia in aquacultur
Mirror matter admixtures in K_L \to \gamma\gamma
Based on possible albeit tiny, admixtures of mirror matter in ordinary mesons
we study the K_L \to \gamma\gamma transition. We find that this process can be
described with a small SU(3) symmetry breaking of only 3%. We also determine
the eta-eta' mixing angle and the pseudoscalar decay constants. The results for
these parameters are consistent with some obtained in the literature. They
favor two recent determinations; one based on two analytical constraints, and
another one based on next-to-leading order power corrections
El Service-Learning o Aprendizaje-Servicio como método de enseñanza: experiencia de la Pace University (Nueva York) en la creación de Green Maps o Mapas Verdes en el marco del desarrollo sostenible del turismo
El trabajo se centra en el Service-Learning o Aprendizaje-Servicio como método de enseñanza innovador. Como ejemplo de su aplicación presentamos los proyectos internacionales puestos en marcha en los estudios de Turismo de la Pace University (Nueva York) para la creación de green maps o mapas verdes de comunidades locales en el marco del Desarrollo Sostenible del Turismo.This paper focuses on Service-Learning as an innovative teaching method. As an example of its application, we present the international projects initiated by Pace University Tourism students for the creation of Green Maps of local communities in order to contribute towards Sustainable Tourism Development
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