737 research outputs found
Gender inequality and sex differences in physical fighting, physical activity, and injury among adolescents across 36 countries
Purpose: Sex differences in adolescent health are widely documented, but social explanations for these sex differences are scarce. This study examines whether societal gender inequality (i.e., men’s and women’s unequal share in political participation, decision-making power, economic participation and command over resources) relates to sex differences in adolescent physical fighting, physical activity, and injuries. Methods: National-level data on gender inequality (i.e. the United Nations Development Program’s Gender Inequality Index) were linked to health data from 71,255 15-year olds from 36 countries in the 2009/10 Health Behavior in School-aged Children (HBSC) study. Using multilevel logistic regression analyses, we tested the association between gender inequality and sex differences in health while controlling for country wealth (GDP per capita). Results: In all countries, boys reported more physical fighting, physical activity, and injuries than girls, but the magnitude of these sex differences varied greatly between countries. Societal gender inequality positively related to sex differences in all three outcomes. In more gender unequal countries, boys reported higher levels of fighting and physical activity, compared to boys in more gender equal countries. In girls, scores were consistently low for these outcomes, however injury was more common in countries with less gender inequality. Conclusions: Societal gender inequality appears to relate to sex differences in some adolescent health behaviors and may contribute to the establishment of sex differences in morbidity and mortality. To reduce inequalities in the health of future generations, public health policy should target social and cultural factors that shape perceived gender norms in young people
Large and small-scale structures and the dust energy balance problem in spiral galaxies
The interstellar dust content in galaxies can be traced in extinction at
optical wavelengths, or in emission in the far-infrared. Several studies have
found that radiative transfer models that successfully explain the optical
extinction in edge-on spiral galaxies generally underestimate the observed
FIR/submm fluxes by a factor of about three. In order to investigate this
so-called dust energy balance problem, we use two Milky Way-like galaxies
produced by high-resolution hydrodynamical simulations. We create mock optical
edge-on views of these simulated galaxies (using the radiative transfer code
SKIRT), and we then fit the parameters of a basic spiral galaxy model to these
images (using the fitting code FitSKIRT). The basic model includes smooth
axisymmetric distributions along a S\'ersic bulge and exponential disc for the
stars, and a second exponential disc for the dust. We find that the dust mass
recovered by the fitted models is about three times smaller than the known dust
mass of the hydrodynamical input models. This factor is in agreement with
previous energy balance studies of real edge-on spiral galaxies. On the other
hand, fitting the same basic model to less complex input models (e.g. a smooth
exponential disc with a spiral perturbation or with random clumps), does
recover the dust mass of the input model almost perfectly. Thus it seems that
the complex asymmetries and the inhomogeneous structure of real and
hydrodynamically simulated galaxies are a lot more efficient at hiding dust
than the rather contrived geometries in typical quasi-analytical models. This
effect may help explain the discrepancy between the dust emission predicted by
radiative transfer models and the observed emission in energy balance studies
for edge-on spiral galaxies.Comment: 9 pages, 5 figures, accepted for publication in A&
A Regional Case Study: Effective Administrator Feedback to Inform Teacher Performance
In 2013, the Michigan Department of Education required all public school districts to adopt a state-approved evaluation system. The Department’s rationale for this change was to increase teacher accountability and thus to improve student achievement. Because schoollevel administrators are responsible for implementing district policy and acting as the primary evaluators of teacher performance, the authors conducted a study to identify the type of administrator feedback principals give in observations and evaluations. In this 3-year study, evaluation data were collected from random districts within a rural Michigan Intermediate School District and analyzed for average total score and manner of feedback. Three primary results emerged. First, the rating count and average score per element rated varied widely; second, evaluators frequently provided comments with each rating; and finally, these evaluators’ comments were not actionable for teacher performance improvement. The results of this work suggest a need for clarity around the definition and purpose of feedback in teacher performance evaluations
The distribution of interstellar dust in CALIFA edge-on galaxies via oligochromatic radiative transfer fitting
We investigate the amount and spatial distribution of interstellar dust in
edge-on spiral galaxies, using detailed radiative transfer modeling of a
homogeneous sample of 12 galaxies selected from the CALIFA survey. Our
automated fitting routine, FitSKIRT, was first validated against artificial
data. This is done by simultaneously reproducing the SDSS -, -, - and
-band observations of a toy model in order to combine the information
present in the different bands. We show that this combined, oligochromatic
fitting, has clear advantages over standard monochromatic fitting especially
regarding constraints on the dust properties. We model all galaxies in our
sample using a three-component model, consisting of a double exponential disc
to describe the stellar and dust discs and using a S\'ersic profile to describe
the central bulge. The full model contains 19 free parameters, and we are able
to constrain all these parameters to a satisfactory level of accuracy without
human intervention or strong boundary conditions. Apart from two galaxies, the
entire sample can be accurately reproduced by our model. We find that the dust
disc is about 75% more extended but only half as high as the stellar disc. The
average face-on optical depth in the V-band is and the spread of
within our sample is quite substantial, which indicates that some spiral
galaxies are relatively opaque even when seen face-on.Comment: 18 pages, 6 figures, 4 tables, Accepted for publication in MNRA
A decade of ejecta dust formation in the Type IIn SN 2005ip
In order to understand the contribution of core-collapse supernovae to the
dust budget of the early universe, it is important to understand not only the
mass of dust that can form in core-collapse supernovae but also the location
and rate of dust formation. SN 2005ip is of particular interest since dust has
been inferred to have formed in both the ejecta and the post-shock region
behind the radiative reverse shock. We have collated eight optical archival
spectra that span the lifetime of SN 2005ip and we additionally present a new
X-shooter optical-near-IR spectrum of SN 2005ip at 4075d post-discovery. Using
the Monte Carlo line transfer code DAMOCLES, we have modelled the blueshifted
broad and intermediate width H, H and He I lines from 48d to
4075d post-discovery using an ejecta dust model. We find that dust in the
ejecta can account for the asymmetries observed in the broad and intermediate
width H, H and He I line profiles at all epochs and that it is
not necessary to invoke post-shock dust formation to explain the blueshifting
observed in the intermediate width post-shock lines. Using a Bayesian approach,
we have determined the evolution of the ejecta dust mass in SN 2005ip over 10
years presuming an ejecta dust model, with an increasing dust mass from
~10 M at 48d to a current dust mass of 0.1 M.Comment: Accepted by MNRAS, 17 pages, 11 figures. Author accepted manuscript.
Accepted on 04/03/19. Deposited on 07/03/1
The mass, location and heating of the dust in the Cassiopeia A supernova remnant
We model the thermal dust emission from dust grains heated by synchrotron
radiation and by particle collisions, under conditions appropriate for four
different shocked and unshocked gas components of the Cassiopeia A (Cas A)
supernova remnant (SNR). By fitting the resulting spectral energy distributions
(SEDs) to the observed SNR dust fluxes, we determine the required mass of dust
in each component. We find the observed SED can be reproduced by of silicate grains, the majority of which is in the unshocked
ejecta and heated by the synchrotron radiation field. Warmer dust, located in
the X-ray emitting reverse shock and blastwave regions, contribute to the
shorter wavelength infrared emission but make only a small fraction of the
total dust mass. Carbon grains can at most make up of the total
dust mass. Combined with estimates for the gas masses, we obtain dust-to-gas
mass ratios for each component, which suggest that the condensation efficiency
in the ejecta is high, and that dust in the shocked ejecta clumps is well
protected from destruction by sputtering in the reverse shock.Comment: Accepted by MNRAS, 14 pages, 6 figures. Author accepted manuscript.
Accepted on 05/02/2019. Deposited on 05/02/201
Сократівсько-платонівські версії мужності як спроба знайдення засобу синхронізації індивідуальної та колективної суверенності
У статті аналізується соціально-політична цінність мужності в її сократівсько-платонівській версії, що
забезпечує синхронізацію індивідуальної та колективної суверенності та є ключовою чеснотою ефективного
існування публічного простору.В статье анализируется социально-политическая ценность мужества в ее сократовско-платоновской версии,
которая обеспечивает синхронизацию индивидуальной и коллективной суверенности и является ключевой
добродетелью существования публичного пространства.In the article the socio-political value of courage is analysed in its sokrat-plato version which provides synchronization
of individual and collective sovereignty and is the key virtue of existence of public space
The Herschel exploitation of local galaxy Andromeda (HELGA) V: Strengthening the case for substantial interstellar grain growth
In this paper we consider the implications of the distributions of dust and
metals in the disc of M31. We derive mean radial dust distributions using a
dust map created from Herschel images of M31 sampling the entire far-infrared
(FIR) peak. Modified blackbodies are fit to approximately 4000 pixels with a
varying, as well as a fixed, dust emissivity index (beta). An overall metal
distribution is also derived using data collected from the literature. We use a
simple analytical model of the evolution of the dust in a galaxy with dust
contributed by stellar sources and interstellar grain growth, and fit this
model to the radial dust-to-metals distribution across the galaxy. Our analysis
shows that the dust-to-gas gradient in M31 is steeper than the metallicity
gradient, suggesting interstellar dust growth is (or has been) important in
M31. We argue that M31 helps build a case for cosmic dust in galaxies being the
result of substantial interstellar grain growth, while the net dust production
from stars may be limited. We note, however, that the efficiency of dust
production in stars, e.g., in supernovae (SNe) ejecta and/or stellar
atmospheres, and grain destruction in the interstellar medium (ISM) may be
degenerate in our simple model. We can conclude that interstellar grain growth
by accretion is likely at least as important as stellar dust production
channels in building the cosmic dust component in M31.Comment: 12 pages, 7 figures. Published in MNRAS 444, 797. This version is
updated to match the published versio
The selective effect of environment on the atomic and molecular gas-to-dust ratio of nearby galaxies in the Herschel Reference Survey
We combine dust, atomic (HI) and molecular (H) hydrogen mass
measurements for 176 galaxies in the Herschel Reference Survey to investigate
the effect of environment on the gas-to-dust mass ()
ratio of nearby galaxies. We find that, at fixed stellar mass, the average
ratio varies by no more than a factor of 2
when moving from field to cluster galaxies, with Virgo galaxies being slightly
more dust rich (per unit of gas) than isolated systems. Remarkably, once the
molecular and atomic hydrogen phases are investigated separately, we find that
\hi-deficient galaxies have at the same time lower
ratio but higher ratio than \hi-normal systems. In
other words, they are poorer in atomic but richer in molecular hydrogen if
normalized to their dust content. By comparing our findings with the
predictions of theoretical models, we show that the opposite behavior observed
in the and ratios is
fully consistent with outside-in stripping of the interstellar medium (ISM),
and is simply a consequence of the different distribution of dust, \hi\ and
H across the disk. Our results demonstrate that the small environmental
variations in the total ratio, as well as in the
gas-phase metallicity, do not automatically imply that environmental mechanisms
are not able to affect the dust and metal content of the ISM in galaxies.Comment: 11 pages, 6 figures, 2 tables. Accepted for publication in MNRA
HERschel Observations of Edge-on Spirals (HEROES). II: Tilted-ring modelling of the atomic gas disks
Context. Edge-on galaxies can offer important insights in galaxy evolution as
they are the only systems where the distribution of the different components
can be studied both radially and vertically. The HEROES project was designed to
investigate the interplay between the gas, dust, stars and dark matter (DM) in
a sample of 7 massive edge-on spiral galaxies.
Aims. In this second HEROES paper we present an analysis of the atomic gas
content of 6 out of 7 galaxies in our sample. The remaining galaxy was recently
analysed according to the same strategy. The primary aim of this work is to
constrain the surface density distribution, the rotation curve and the geometry
of the gas disks in a homogeneous way. In addition we identify peculiar
features and signs of recent interactions.
Methods. We construct detailed tilted-ring models of the atomic gas disks
based on new GMRT 21-cm observations of NGC 973 and UGC 4277 and re-reduced
archival HI data of NGC 5907, NGC 5529, IC 2531 and NGC 4217. Potential
degeneracies between different models are resolved by requiring a good
agreement with the data in various representations of the data cubes.
Results. From our modelling we find that all but one galaxy are warped along
the major axis. In addition, we identify warps along the line of sight in three
galaxies. A flaring gas layer is required to reproduce the data only for one
galaxy, but (moderate) flares cannot be ruled for the other galaxies either. A
coplanar ring-like structure is detected outside the main disk of NGC 4217,
which we suggest could be the remnant of a recent minor merger event. We also
find evidence for a radial inflow of 15 +- 5 km/s in the disk of NGC 5529,
which might be related to the ongoing interaction with two nearby companions.
(Abridged)Comment: 39 pages, 38 figures, Accepted for publication in Astronomy &
Astrophysic
- …