3,145 research outputs found
Microlensing of the broad-line region in the quadruply imaged quasar HE0435-1223
Using infrared spectra of the z = 1.693 quadruply lensed quasar HE0435-1223
acquired in 2009 with the spectrograph SINFONI at the ESO Very Large Telescope,
we have detected a clear microlensing effect in images A and D. While
microlensing affects the blue and red wings of the H{\alpha} line profile in
image D very differently, it de-magnifies the line core in image A. The
combination of these different effects sets constraints on the line-emitting
region; these constraints suggest that a rotating ring is at the origin of the
H{\alpha} line. Visible spectra obtained in 2004 and 2012 indicate that the
MgII line profile is microlensed in the same way as the H{\alpha} line. Our
results therefore favour flattened geometries for the low-ionization
line-emitting region, for example, a Keplerian disk. Biconical models cannot be
ruled out but require more fine-tuning. Flux ratios between the different
images are also derived and confirm flux anomalies with respect to estimates
from lens models with smooth mass distributions.Comment: 6 pages, 4 figures, 3 tables, accepted by A&A on 10 April 201
Supersymmetric Quantum Mechanics, multiphoton algebras and coherent states
The multiphoton algebras for one-dimensional Hamiltonians with infinite
discrete spectrum, and for their associated kth-order SUSY partners are
studied. In both cases, such an algebra is generated by the multiphoton
annihilation and creation operators, as well as by Hamiltonians which are
functions of an appropriate number operator. The algebras obtained turn out to
be polynomial deformations of the corresponding single-photon algebra
previously studied. The Barut-Girardello coherent states, which are eigenstates
of the annihilation operator, are obtained and their uncertainty relations are
explored by means of the associated quadratures.Comment: Last version of the paper, 6 figure
BRST-BFV method for nonstationary systems
Starting from an associated reparametrization-invariant action, the
generalization of the BRST-BFV method for the case of nonstationary systems is
constructed. The extension of the Batalin-Tyutin conversional approach is also
considered in the nonstationary case. In order to illustrate these ideas, the
propagator for the time-dependent two-dimensional rotor is calculated by
reformulating the problem as a system with only first class constraints and
subsequently using the BRST-BFV prescription previously obtained.Comment: Latex, RevTeX, 13 page
Low-frequency radio spectra of submillimetre galaxies in the Lockman Hole
We investigate the radio properties of a sample of 53 sources selected at 850
m from the SCUBA-2 Cosmology Legacy Survey using new deep, low-frequency
radio imaging of the Lockman Hole field from the Low Frequency Array. Combining
these data with additional radio observations from the GMRT and the JVLA, we
find a variety of radio spectral shapes and luminosities within our sample
despite their similarly bright submillimetre flux densities. We characterise
their spectral shapes in terms of multi-band radio spectral indices. Finding
strong spectral flattening at low frequencies in ~20% of sources, we
investigate the differences between sources with extremely flat low-frequency
spectra and those with `normal' radio spectral indices. As there are no other
statistically significant differences between the two subgroups of our sample
as split by the radio spectral index, we suggest that any differences are
undetectable in galaxy-averaged properties that we can observe with our
unresolved images, and likely relate to galaxy properties that we cannot
resolve, on scales 1 kpc. We attribute the observed spectral
flattening in the radio to free-free absorption, proposing that those sources
with significant low-frequency spectral flattening have a clumpy distribution
of star-forming gas. We estimate an average spatial extent of absorbing
material of at most several hundred parsecs to produce the levels of absorption
observed in the radio spectra. This estimate is consistent with the
highest-resolution observations of submillimetre galaxies in the literature,
which find examples of non-uniform dust distributions on scales of ~100 pc,
with evidence for clumps and knots in the interstellar medium. Additionally, we
find two bright (> 6 mJy) submm sources undetected at all other wavelengths. We
speculate that these objects may be very high redshift sources, likely residing
at z > 4.Comment: 15 pages, 10 figures, accepted by A&
VHMPID: a new detector for the ALICE experiment at LHC
This article presents the basic idea of VHMPID, an upgrade detector for the
ALICE experiment at LHC, CERN. The main goal of this detector is to extend the
particle identification capabilities of ALICE to give more insight into the
evolution of the hot and dense matter created in Pb-Pb collisions. Starting
from the physics motivations and working principles the challenges and current
status of development is detailed.Comment: 4 pages, 6 figures. To be published in EPJ Web of Conference
Environmental variables, habitat discontinuity and life history shaping the genetic structure of Pomatoschistus marmoratus
Coastal lagoons are semi-isolated ecosystems
exposed to wide fluctuations of environmental conditions
and showing habitat fragmentation. These features may
play an important role in separating species into different
populations, even at small spatial scales. In this study, we
evaluate the concordance between mitochondrial (previous
published data) and nuclear data analyzing the genetic
variability of Pomatoschistus marmoratus in five localities,
inside and outside the Mar Menor coastal lagoon (SE
Spain) using eight microsatellites. High genetic diversity
and similar levels of allele richness were observed across
all loci and localities, although significant genic and
genotypic differentiation was found between populations
inside and outside the lagoon. In contrast to the FST values
obtained from previous mitochondrial DNA analyses
(control region), the microsatellite data exhibited significant
differentiation among samples inside the Mar Menor
and between lagoonal and marine samples. This pattern
was corroborated using Cavalli-Sforza genetic distances.
The habitat fragmentation inside the coastal lagoon and
among lagoon and marine localities could be acting as a
barrier to gene flow and contributing to the observed
genetic structure. Our results from generalized additive
models point a significant link between extreme lagoonal
environmental conditions (mainly maximum salinity) and
P. marmoratus genetic composition. Thereby, these environmental
features could be also acting on genetic structure
of coastal lagoon populations of P. marmoratus favoring
their genetic divergence. The mating strategy of P. marmoratus
could be also influencing our results obtained from
mitochondrial and nuclear DNA. Therefore, a special
consideration must be done in the selection of the DNA
markers depending on the reproductive strategy of the
species
Towns with extremely low mortality due to ischemic heart disease in Spain
BACKGROUND: The cause of coronary disease inframortality in Spain is unknown. The aim of this study is to identify Spanish towns with very low ischemic heart disease mortality, describe their health and social characteristics, and analyze the relationship with a series of contextual factors. METHODS: We obtained the number of deaths registered for each of 8,122 Spanish towns in the periods 1989-1998 and 1999-2003. Expected deaths, standardized mortality ratio (SMR), smoothed Relative Risk (RR), and Posterior Probability (PP) of RR > 1 were calculated using Bayesian hierarchical models. Inframortality was defined as any town that displayed an RR below the 10th percentile, an SMR of under 1 for both sexes, and a PP of RR > 1 less than or equal to 0.002 for male and 0.005 for female mortality, during the two periods covered. All the remaining towns, except for those with high mortality classified as "tourist towns", were selected as controls. The association among socioeconomic, health, dietary, lifestyle and vascular risk factors was analyzed using sequential mixed logistic regression models, with province as the random-effects variable. RESULTS: We identified 32 towns in which ischemic heart disease mortality was half the national rate and four times lower than the European Union rate, situated in lightly populated provinces spread across the northern half of Spain, and revealed a surprising pattern of geographic aggegation for 23 of the 32 towns. Variables related with inframortality were: a less aged population (OR 0.93, 95% CI 0.89-0.99); a contextual dietary pattern marked by a high fish content (OR 2.13, 95% CI 1.38-3.28) and wine consumption (OR 1.50, 95% CI 1.08-2.07); and a low prevalence of obesity (OR 0.47, 95% CI 0.22-1.01); and, in the case of towns of over 1000 inhabitants, a higher physician-population ratio (OR 3.80, 95% CI 1.17-12.3). CONCLUSIONS: Results indicate that dietary and health care factors have an influence on inframortality. The geographical aggregation suggests that other factors with a spatial pattern, e.g., genetic or environmental might also be implicated. These results will have to be confirmed by studies in situ, with objective measurements at an individual level.This study was funded by research study grant no. PI06/0656 from Spain's Health Research Fund (Fondo de Investigación Sanitaria).S
High overlap between traditional ecological knowledge and forest conservation found in the Bolivian Amazon
Unidad de excelencia María de Maeztu MdM-2015-0552Altres ajuts: FBBVA research grant (BIOCON_06_106-07)It has been suggested that traditional ecological knowledge (TEK) may play a key role in forest conservation. However, empirical studies assessing to what extent TEK is associated with forest conservation compared with other variables are rare. Furthermore, to our knowledge, the spatial overlap of TEK and forest conservation has not been evaluated at fine scales. In this paper, we address both issues through a case study with Tsimane' Amerindians in the Bolivian Amazon. We sampled 624 households across 59 villages to estimate TEK and used remote sensing data to assess forest conservation. We ran statistical and spatial analyses to evaluate whether TEK was associated and spatially overlapped with forest conservation at the village level. We find that Tsimane' TEK is significantly and positively associated with forest conservation although acculturation variables bear stronger and negative associations with forest conservation. We also find a very significant spatial overlap between levels of Tsimane' TEK and forest conservation. We discuss the potential reasons underpinning our results, which provide insights that may be useful for informing policies in the realms of development, conservation, and climate. We posit that the protection of indigenous cultural systems is vital and urgent to create more effective policies in such realms
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