330 research outputs found
The role of parental smoking on adolescent smoking and its social patterning: a cross-sectional survey in six European cities
Background Several studies have observed socio-economic (SE) inequalities in smoking among adolescents, but its causes are not fully understood. This study investigates the association between parental and adolescent smoking, and whether this association is socially patterned. Methods We used data from a survey administered in 2013 to students aged 14-17 years old of six European cities (n = 10 526). Using multilevel mixed-effects logistic regression, we modelled the probability of being a daily smoker as a function of parental smoking and SE status. We tested whether the smoking association differed across social strata. Results The prevalence of parental smoking was higher in low SE status adolescents. Boys and girls were more likely to smoke if they have a father [boys: adjusted odds ratio (AOR) = 1.90, 95% CI = 1.47-2.46; girls: AOR = 1.42, 95% CI = 1.09-1.86] and mother (boys: AOR = 1.77, 95% CI = 1.35-2.31; girls: AOR = 3.36, 95% CI = 2.56-4.40) who smoked. Among boys, the odds of smoking when having a smoking parent were higher in lower SE classes. However, this was not statistically significant, nor was it observed among girls. Conclusions Adolescents are more likely to smoke when their father and mother smoke. Although the susceptibility to parental smoking was similar across social classes, SE differences in parental smoking contribute to the transmission of SE inequalities in smokin
Phenotypic redshifts with self-organizing maps: A novel method to characterize redshift distributions of source galaxies for weak lensing
Wide-field imaging surveys such as the Dark Energy Survey (DES) rely on
coarse measurements of spectral energy distributions in a few filters to
estimate the redshift distribution of source galaxies. In this regime, sample
variance, shot noise, and selection effects limit the attainable accuracy of
redshift calibration and thus of cosmological constraints. We present a new
method to combine wide-field, few-filter measurements with catalogs from deep
fields with additional filters and sufficiently low photometric noise to break
degeneracies in photometric redshifts. The multi-band deep field is used as an
intermediary between wide-field observations and accurate redshifts, greatly
reducing sample variance, shot noise, and selection effects. Our implementation
of the method uses self-organizing maps to group galaxies into phenotypes based
on their observed fluxes, and is tested using a mock DES catalog created from
N-body simulations. It yields a typical uncertainty on the mean redshift in
each of five tomographic bins for an idealized simulation of the DES Year 3
weak-lensing tomographic analysis of , which is a
60% improvement compared to the Year 1 analysis. Although the implementation of
the method is tailored to DES, its formalism can be applied to other large
photometric surveys with a similar observing strategy.Comment: 24 pages, 11 figures; matches version accepted to MNRA
Chemodynamics of the Milky Way. I. The first year of APOGEE data
We investigate the chemo-kinematic properties of the Milky Way disc by exploring the first year of data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), and compare our results to smaller optical high-resolution samples in the literature, as well as results from lower resolution surveys such as GCS, SEGUE and RAVE. We start by selecting a high-quality sample in terms of chemistry (____sim 20.000 stars) and, after computing distances and orbital parameters for this sample, we employ a number of useful subsets to formulate constraints on Galactic chemical and chemodynamical evolution processes in the Solar neighbourhood and beyond (e.g., metallicity distributions -- MDFs, [____alpha/Fe] vs. [Fe/H] diagrams, and abundance gradients). Our red giant sample spans distances as large as 10 kpc from the Sun. We find remarkable agreement between the recently published local (d 100 pc) high-resolution high-S/N HARPS sample and our local HQ sample (d 1 kpc). The local MDF peaks slightly below solar metallicity, and exhibits an extended tail towards [Fe/H] 1, whereas a sharper cut-off is seen at larger metallicities. The APOGEE data also confirm the existence of a gap in the [____alpha/Fe] vs. [Fe/H] abundance diagram. When expanding our sample to cover three different Galactocentric distance bins, we find the high-[____alpha/Fe] stars to be rare towards the outer zones, as previously suggested in the literature. For the gradients in [Fe/H] and [____alpha/Fe], measured over a range of 6 R 11 kpc in Galactocentric distance, we find a good agreement with the gradients traced by the GCS and RAVE dwarf samples. For stars with 1.5 z 3 kpc, we find a positive metallicity gradient and a negative gradient in [____alpha/Fe]
Clusters of galaxies : observational properties of the diffuse radio emission
Clusters of galaxies, as the largest virialized systems in the Universe, are
ideal laboratories to study the formation and evolution of cosmic
structures...(abridged)... Most of the detailed knowledge of galaxy clusters
has been obtained in recent years from the study of ICM through X-ray
Astronomy. At the same time, radio observations have proved that the ICM is
mixed with non-thermal components, i.e. highly relativistic particles and
large-scale magnetic fields, detected through their synchrotron emission. The
knowledge of the properties of these non-thermal ICM components has increased
significantly, owing to sensitive radio images and to the development of
theoretical models. Diffuse synchrotron radio emission in the central and
peripheral cluster regions has been found in many clusters. Moreover
large-scale magnetic fields appear to be present in all galaxy clusters, as
derived from Rotation Measure (RM) studies. Non-thermal components are linked
to the cluster X-ray properties, and to the cluster evolutionary stage, and are
crucial for a comprehensive physical description of the intracluster medium.
They play an important role in the cluster formation and evolution. We review
here the observational properties of diffuse non-thermal sources detected in
galaxy clusters: halos, relics and mini-halos. We discuss their classification
and properties. We report published results up to date and obtain and discuss
statistical properties. We present the properties of large-scale magnetic
fields in clusters and in even larger structures: filaments connecting galaxy
clusters. We summarize the current models of the origin of these cluster
components, and outline the improvements that are expected in this area from
future developments thanks to the new generation of radio telescopes.Comment: Accepted for the publication in The Astronomy and Astrophysics
Review. 58 pages, 26 figure
Constraining radio mode feedback in galaxy clusters with the cluster radio AGNs properties to z ∼ 1
We study the properties of the Sydney University Molonglo Sky Survey (SUMSS) 843 MHz radio active galactic nuclei (AGNs) population in galaxy clusters from two large catalogues created using the Dark Energy Survey (DES): ∼11 800 optically selected RM-Y3 and ∼1000 X-ray selected MARD-Y3 clusters. We show that cluster radio loud AGNs are highly concentrated around cluster centres to z ∼ 1. We measure the halo occupation number for cluster radio AGNs above a threshold luminosity, finding that the number of radio AGNs per cluster increases with cluster halo mass as N ∝ M1.2 ± 0.1 (N ∝ M0.68 ± 0.34) for the RM-Y3 (MARD-Y3) sample. Together, these results indicate that radio mode feedback is favoured in more massive galaxy clusters. Using optical counterparts for these sources, we demonstrate weak redshift evolution in the host broad-band colours and the radio luminosity at fixed host galaxy stellar mass. We use the redshift evolution in radio luminosity to break the degeneracy between density and luminosity evolution scenarios in the redshift trend of the radio AGNs luminosity function (LF). The LF exhibits a redshift trend of the form (1 + z)γ in density and luminosity, respectively, of γD = 3.0 ± 0.4 and γP = 0.21 ± 0.15 in the RM-Y3 sample, and γD = 2.6 ± 0.7 and γP = 0.31 ± 0.15 in MARD-Y3. We discuss the physical drivers of radio mode feedback in cluster AGNs, and we use the cluster radio galaxy LF to estimate the average radio-mode feedback energy as a function of cluster mass and redshift and compare it to the core (<0.1R500) X-ray radiative losses for clusters at z < 1
Finding meaning: HIV self-management and wellbeing among people taking antiretroviral therapy in Uganda
© 2016 Russell et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in anymedium, provided the original author and source are credited. The health of people living with HIV (PLWH) and the sustained success of antiretroviral therapy (ART) programmes depends on PLWH's motivation and ability to self-manage the condition over the long term, including adherence to drugs on a daily basis. PLWH's selfmanagement of HIV and their wellbeing are likely to be interrelated. Successful self-management sustains wellbeing, and wellbeing is likely to motivate continued self-management. Detailed research is lacking on PLWH's self-management processes on ART in resourcelimited settings. This paper presents findings from a study of PLWH's self-management and wellbeing in Wakiso District, Uganda. Thirty-eight PLWH (20 women, 18 men) were purposefully selected at ART facilities run by the government and by The AIDS Support Organisation in and around Entebbe. Two in-depth interviews were completed with each participant over three or four visits. Many were struggling economically, however the recovery of health and hope on ART had enhanced wellbeing and motivated self-management. The majority were managing their condition well across three broad domains of self-management. First, they had mobilised resources, notably through good relationships with health workers. Advice and counselling had helped them to reconceptualise their condition and situation more positively and see hope for the future, motivating their work to self-manage. Many had also developed a new network of support through contacts they had developed at the ART clinic. Second, they had acquired knowledge and skills to manage their health, a useful framework to manage their condition and to live their life. Third, participants were psychologically adjusting to their condition and their new 'self': They saw HIV as a normal disease, were coping with stigma and had regained self-esteem, and were finding meaning in life. Our study demonstrates the centrality of social relationships and other nonmedical aspects of wellbeing for self-management which ART programmes might explore further and encourage
Dark Energy Survey Year 1 results: the effect of intracluster light on photometric redshifts for weak gravitational lensing
We study the effect of diffuse intracluster light on the critical surface mass density estimated from photometric redshifts of lensing source galaxies, and the resulting bias in a weak lensing measurement of galaxy cluster mass. Under conservative assumptions, we find the bias to be negligible for imaging surveys like the Dark Energy Survey with a recommended scale cut of ≥200kpc distance from cluster centres. For significantly deeper lensing source galaxy catalogues from present and future surveys like the Large Synoptic Survey Telescope program, more conservative scale and source magnitude cuts or a correction of the effect may be necessary to achieve percent level lensing measurement accuracy, especially at the massive end of the cluster population
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Monte Carlo control loops for cosmic shear cosmology with DES Year 1 data
Weak lensing by large-scale structure is a powerful probe of cosmology and of the dark universe. This cosmic shear technique relies on the accurate measurement of the shapes and redshifts of background galaxies and requires precise control of systematic errors. Monte Carlo control loops (MCCL) is a forward modeling method designed to tackle this problem. It relies on the ultra fast image generator (UFig) to produce simulated images tuned to match the target data statistically, followed by calibrations and tolerance loops. We present the first end-to-end application of this method, on the Dark Energy Survey (DES) Year 1 wide field imaging data. We simultaneously measure the shear power spectrum
C
ℓ
and the redshift distribution
n
(
z
)
of the background galaxy sample. The method includes maps of the systematic sources, point spread function (PSF), an approximate Bayesian computation (ABC) inference of the simulation model parameters, a shear calibration scheme, and a fast method to estimate the covariance matrix. We find a close statistical agreement between the simulations and the DES Y1 data using an array of diagnostics. In a nontomographic setting, we derive a set of
C
ℓ
and
n
(
z
)
curves that encode the cosmic shear measurement, as well as the systematic uncertainty. Following a blinding scheme, we measure the combination of
Ω
m
,
σ
8
, and intrinsic alignment amplitude
A
IA
, defined as
S
8
D
IA
=
σ
8
(
Ω
m
/
0.3
)
0.5
D
IA
, where
D
IA
=
1
−
0.11
(
A
IA
−
1
)
. We find
S
8
D
IA
=
0.89
5
+
0.054
−
0.039
, where systematics are at the level of roughly 60% of the statistical errors. We discuss these results in the context of earlier cosmic shear analyses of the DES Y1 data. Our findings indicate that this method and its fast runtime offer good prospects for cosmic shear measurements with future wide-field surveys
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