1,990 research outputs found
Localization of short duration gravitational-wave transients with the early advanced LIGO and Virgo detectors
The Laser Interferometer Gravitational wave Observatory (LIGO) and Virgo,
advanced ground-based gravitational-wave detectors, will begin collecting
science data in 2015. With first detections expected to follow, it is important
to quantify how well generic gravitational-wave transients can be localized on
the sky. This is crucial for correctly identifying electromagnetic counterparts
as well as understanding gravitational-wave physics and source populations. We
present a study of sky localization capabilities for two search and parameter
estimation algorithms: \emph{coherent WaveBurst}, a constrained likelihood
algorithm operating in close to real-time, and \emph{LALInferenceBurst}, a
Markov chain Monte Carlo parameter estimation algorithm developed to recover
generic transient signals with latency of a few hours. Furthermore, we focus on
the first few years of the advanced detector era, when we expect to only have
two (2015) and later three (2016) operational detectors, all below design
sensitivity. These detector configurations can produce significantly different
sky localizations, which we quantify in detail. We observe a clear improvement
in localization of the average detected signal when progressing from
two-detector to three-detector networks, as expected. Although localization
depends on the waveform morphology, approximately 50% of detected signals would
be imaged after observing 100-200 deg in 2015 and 60-110 deg in 2016,
although knowledge of the waveform can reduce this to as little as 22 deg.
This is the first comprehensive study on sky localization capabilities for
generic transients of the early network of advanced LIGO and Virgo detectors,
including the early LIGO-only two-detector configuration.Comment: 18 pages, 8 figure
A Talenti-type comparison theorem for spaces and applications
We prove pointwise and -gradient comparison results for solutions to
elliptic Dirichlet problems defined on open subsets of a (possibly non-smooth)
space with positive Ricci curvature (more precisely of an
metric measure space, with and ). The obtained
Talenti-type comparison is sharp, rigid and stable with respect to
/measured-Gromov-Hausdorff topology; moreover, several aspects seem new
even for smooth Riemannian manifolds. As applications of such Talenti-type
comparison, we prove a series of improved Sobolev-type inequalities, and an
version of the St.~Venant-P\'olya torsional rigidity comparison
theorem (with associated rigidity and stability statements). Finally, we give a
probabilistic interpretation (in the setting of smooth Riemannian manifolds) of
the aforementioned comparison results, in terms of exit time from an open
subset for the Brownian motion.Comment: 35 pages. Final version to appear in Calculus of Variations and
Partial Differential Equation
Health Conditions And Factors Related To The Work Ability Of Teachers.
This is a cross-sectional study conducted with 258 teachers from nine state schools in two municipalities of SĂŁo Paulo state with the purpose of assessing their work ability. A questionnaire with socio-demographic and health/work conditions data and the Work Ability Index (WAI) was performed. Most teachers were females, 41.9â
yr old on average (SD 9.4), and with an undergraduate degree (95.7%). The work ability was considered good for 42.6% and moderate/low for 35.3%. In linear regressions models, which used the two domain model, the significant variables for a decrease in WAI were: individual perception of a worsening in the health situation (p<0001), having children (p=0.0003 / p=0.0001), difficulty in sleeping well at night (p=0.0009 / p=0.0014), history of physical pain in the previous six months (p<0.0001 / p<0.0001), being a teacher with a contract (p=0.0007) and working as a teacher for a longer time. (p=0.0183). Public investments on the work conditions of teachers are important to recover and to maintain their work ability.52121-
A dispersive wave pattern on Jupiter's fastest retrograde jet at S
A compact wave pattern has been identified on Jupiter's fastest retrograding
jet at 20S (the SEBs) on the southern edge of the South Equatorial Belt. The
wave has been identified in both reflected sunlight from amateur observations
between 2010 and 2015, thermal infrared imaging from the Very Large Telescope
and near infrared imaging from the Infrared Telescope Facility. The wave
pattern is present when the SEB is relatively quiescent and lacking large-scale
disturbances, and is particularly notable when the belt has undergone a fade
(whitening). It is generally not present when the SEB exhibits its usual
large-scale convective activity ('rifts'). Tracking of the wave pattern and
associated white ovals on its southern edge over several epochs have permitted
a measure of the dispersion relationship, showing a strong correlation between
the phase speed (-43.2 to -21.2 m/s) and the longitudinal wavelength, which
varied from 4.4-10.0 deg. longitude over the course of the observations.
Infrared imaging sensing low pressures in the upper troposphere suggest that
the wave is confined to near the cloud tops. The wave is moving westward at a
phase speed slower (i.e., less negative) than the peak retrograde wind speed
(-62 m/s), and is therefore moving east with respect to the SEBs jet peak.
Unlike the retrograde NEBn jet near 17N, which is a location of strong vertical
wind shear that sometimes hosts Rossby wave activity, the SEBs jet remains
retrograde throughout the upper troposphere, suggesting the SEBs pattern cannot
be interpreted as a classical Rossby wave. Cassini-derived windspeeds and
temperatures reveal that the vorticity gradient is dominated by the baroclinic
term and becomes negative (changes sign) in a region near the cloud-top level
(400-700 mbar) associated with the SEBs, suggesting a baroclinic origin for
this meandering wave pattern. [Abr]Comment: 19 pages, 11 figures, article accepted for publication in Icaru
Interference at the Single Photon Level Along Satellite-Ground Channels
Quantum interference arising from superposition of states is a striking
evidence of the validity of Quantum Mechanics, confirmed in many experiments
and also exploited in applications. However, as for any scientific theory,
Quantum Mechanics is valid within the limits in which it has been
experimentally verified. In order to extend such limits, it is necessary to
observe quantum interference in unexplored conditions such as moving terminals
at large distance in Space. Here we experimentally demonstrate single photon
interference at a ground station due to the coherent superposition of two
temporal modes reflected by a rapidly moving satellite thousand kilometers
away. The relative speed of the satellite induces a varying modulation in the
interference pattern. The measurement of the satellite distance in real time by
laser ranging allowed us to precisely predict the instantaneous value of the
interference phase. We then observed the interference patterns with visibility
up to with three different satellites and with path length up to 5000
km. Our results attest the viability of photon temporal modes for fundamental
tests of Physics and Quantum Communications in Space.Comment: Version accepted for publication in Phys. Rev. Let
RE-THINKING CRISIS AND CRITIQUE IN THE DISCOURSE ON âREFUGEE CRISISâ IN POSTCOLONIAL EUROPE
ABSTRACT Objective: this essay aims at re-thinking crisis and critique in the discourse on ârefugee crisisâ viewed through the context of migration and European borders, by investigating the role of critique and critical thought in this debate. Methodology: the methodology is based on a postcolonial approach of Europe, in which âpostâ does not simply deal with a temporary issue. Rather it refers to the way colonialism has shaped the European territory itself, leading to asymmetrical relationships between this continent and ex-colonies that still exist. The methodology used is hypothetical-deductive, by reviewing the literature contained in books, scientific articles and international treaties. Results: the paper, as results, show that is fundamental to re-think the discourse on "refugee crises". Contribution: re-think the discourse on ârefugee crisisâ viewed through the context of migration and European borders. Keywords: Refugees; Migration; Refugee Crisis RESUMO Objetivo: este artigo visa repensar a crise e a crĂtica no discurso sobre âcrise de refugiadosâ, visto no contexto da migração e das fronteiras europeias, investigando o papel da crĂtica e do pensamento crĂtico neste debate. Metodologia: a metodologia Ă© baseada em uma abordagem pĂłs-colonial da Europa, na qual o âpĂłsâ nĂŁo trata simplesmente de um problema temporĂĄrio. Pelo contrĂĄrio, refere-se Ă forma como o colonialismo moldou o prĂłprio territĂłrio europeu, levando a relaçÔes assimĂ©tricas entre este continente e ex-colĂŽnias que ainda existem. A metodologia utilizada Ă© hipotĂ©tico-dedutiva, mediante a revisĂŁo de literatura contida em obras, artigos cientĂficos e em tratados internacionais. Resultados: o trabalho mostra que Ă© fundamental repensar o discurso sobre "crise de refugiados". Contribuição: repensar o discurso sobre âcrise de refugiadosâ visto atravĂ©s do contexto da migração e das fronteiras europĂ©ias. Palavras-chave: refugiados; migração; crise de refugiado
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