223 research outputs found
Drinking in the dark: shedding light on young peopleâs alcohol consumption experiences
This paper draws on 12 months of ethnographic research to explore the drinking experiences of young people, aged 15-24, living in the suburban case study locations of Chorlton and Wythenshawe, Manchester, UK. This paper moves beyond the contemporary geographical imaginary of alcohol consumption as a city-centre issue, to explore suburban indoor and outdoor drinking cultures. Through paying attention to atmospheres of darkness and lightness, I show how drinkscapes are active constituents of young peopleâs drinking occasions, rather than passive backdrops. More than this, I illustrate how young people transform dark and light drinkscapes, thereby shaping the drinking practices of themselves and others. Through looking at the interplay between the curating of an atmosphere, and the experience of that atmosphere when bodies, and practices are inserted into it, this paper offers a different take on the âdrinking at home is bad, drinking in public spaces is goodâ argument, with original policy suggestions
Direct cosmological simulations of the growth of black holes and galaxies
We investigate the coupled formation and evolution of galaxies and their
embedded supermassive black holes using state-of-the-art hydrodynamic
simulations of cosmological structure formation. For the first time, we
self-consistently follow the dark matter dynamics, radiative gas cooling, star
formation, as well as black hole growth and associated feedback processes,
starting directly from initial conditions appropriate for the LambdaCDM
cosmology. Our modeling of the black hole physics is based on an approach we
have developed in simulations of isolated galaxy mergers. Here we examine: (i)
the predicted global history of black hole mass assembly (ii) the evolution of
the local black hole-host mass correlations and (iii) the conditions that allow
rapid growth of the first quasars, and the properties of their hosts and
descendants today. We find a total black hole mass density in good agreement
with observational estimates. The black hole accretion rate density peaks at
lower redshift and evolves more strongly at high redshift than the star
formation rate density, but the ratio of black hole to stellar mass densities
shows only a moderate evolution at low redshifts. We find strong correlations
between black hole masses and properties of the stellar systems, agreeing well
with the measured local M_BH-sigma and M_BH -M_* relationships, but also
suggesting (dependent on the mass range) a weak evolution with redshift in the
normalization and the slope. Our simulations also produce massive black holes
at high redshift, due to extended periods of exponential growth in regions that
collapse early and exhibit strong gas inflows. These first supermassive BH
systems however are not necessarily the most massive ones today, since they are
often overtaken in growth by quasars that form later. (abridged)Comment: 22 pages, 17 figures, submitted to Ap
Gas driven massive black hole binaries: signatures in the nHz gravitational wave background
Pulsar timing arrays (PTAs) measure nHz frequency gravitational waves (GWs)
generated by orbiting massive black hole binaries (MBHBs) with periods between
0.1-10 yr. Previous studies on the nHz GW background assumed that the inspiral
is purely driven by GWs. However, torques generated by a gaseous disk can
shrink the binary much more efficiently than GW emission, reducing the number
of binaries at these separations. We use simple disk models for the
circumbinary gas and for the binary-disk interaction to follow the orbital
decay of MBHBs through physically distinct regions of the disk, until GWs take
over their evolution. We extract MBHB cosmological merger rates from the
Millennium simulation, generate Monte Carlo realizations of a population of gas
driven binaries, and calculate the corresponding GW amplitudes of the most
luminous individual binaries and the stochastic GW background. For steady state
alpha-disks with alpha>0.1 we find that the nHz GW background can be
significantly modified. The number of resolvable binaries is however not
changed by the presence of gas; we predict 1-10 individually resolvable sources
to stand above the noise for a 1-50 ns timing precision. Gas driven migration
reduces predominantly the number of small total mass or unequal mass ratio
binaries, which leads to the attenuation of the mean stochastic GW--background,
but increases the detection significance of individually resolvable binaries.
The results are sensitive to the model of binary--disk interaction. The GW
background is not attenuated significantly for time-dependent models of Ivanov,
Papaloizou, & Polnarev (1999).Comment: Accepted by MNRAS, 15 pages, 8 figure
Angular Momentum and the Formation of Stars and Black Holes
The formation of compact objects like stars and black holes is strongly
constrained by the requirement that nearly all of the initial angular momentum
of the diffuse material from which they form must be removed or redistributed
during the formation process. The mechanisms that may be involved and their
implications are discussed for (1) low-mass stars, most of which probably form
in binary or multiple systems; (2) massive stars, which typically form in
clusters; and (3) supermassive black holes that form in galactic nuclei. It is
suggested that in all cases, gravitational interactions with other stars or
mass concentrations in a forming system play an important role in
redistributing angular momentum and thereby enabling the formation of a compact
object. If this is true, the formation of stars and black holes must be a more
complex, dynamic, and chaotic process than in standard models. The
gravitational interactions that redistribute angular momentum tend to couple
the mass of a forming object to the mass of the system, and this may have
important implications for mass ratios in binaries, the upper stellar IMF in
clusters, and the masses of supermassive black holes in galaxies.Comment: Accepted by Reports on Progress in Physic
The Consumption, Production and Regulation of Alcohol in the UK: The Relevance of the Ambivalence of the Carnivalesque
Alcohol consumption in 21st-century Britain is of significant interest to government, media and academics. Some have referred to a ânew culture of intoxicationâ or âcalculated hedonismâ, fostered by the drinks industry, and enabled by a neoliberal policymaking context. This article argues that the âcarnivalesqueâ is a better concept through which to understand alcoholâs place in British society today. The concept of the carnivalesque conveys an earthy yet extraordinary culture of drinking, as well as ritual elements with a lack of comfort and security that characterise the night-time economy for many people. This night-time carnival, as well as being something experienced by participants, is also a spectacle, with gendered and classed dynamics. It is suggested that this concept is helpful in making sense of common understandings of alcohol that run through the spheres not only of alcohol consumption but also production and regulation
Sizes and ages of SDSS ellipticals: Comparison with hierarchical galaxy formation models
In a sample of about 45,700 early-type galaxies extracted from SDSS, we find
that the shape, normalization, and dispersion around the mean size-stellar mass
relation is the same for young and old systems, provided the stellar mass is
greater than 3*10^10 Msun. This is difficult to reproduce in pure passive
evolution models, which generically predict older galaxies to be much more
compact than younger ones of the same stellar mass. However, this aspect of our
measurements is well reproduced by hierarchical models of galaxy formation.
Whereas the models predict more compact galaxies at high redshifts, subsequent
minor, dry mergers increase the sizes of the more massive objects, resulting in
a flat size-age relation at the present time. At lower masses, the models
predict that mergers are less frequent, so that the expected anti-correlation
between age and size is not completely erased. This is in good agreement with
our data: below 3*10^10 Msun, the effective radius R_e is a factor of ~2 lower
for older galaxies. These successes of the models are offset by the fact that
the predicted sizes have other serious problems, which we discuss.Comment: 13 pages, 9 Figures, 1 Table. Accepted by MNRA
Modeling the cosmological co-evolution of supermassive black holes and galaxies: I. BH scaling relations and the AGN luminosity function
We model the cosmological co-evolution of galaxies and their central
supermassive black holes (BHs) within a semi-analytical framework developed on
the outputs of the Millennium Simulation. This model, described in detail in
Croton et al. (2006) and De Lucia & Blaizot (2007), introduces a `radio mode'
feedback from Active Galactic Nuclei (AGN) at the centre of X-ray emitting
atmospheres in galaxy groups and clusters. Thanks to this mechanism, the model
can simultaneously explain: (i) the low observed mass drop-out rate in cooling
flows; (ii) the exponential cut-off in the bright end of the galaxy luminosity
function; and (iii) the bulge-dominated morphologies and old stellar ages of
the most massive galaxies in clusters. This paper is the first of a series in
which we investigate how well this model can also reproduce the physical
properties of BHs and AGN. Here we analyze the scaling relations, the
fundamental plane and the mass function of BHs, and compare them with the most
recent observational data. Moreover, we extend the semi-analytic model to
follow the evolution of the BH mass accretion and its conversion into
radiation, and compare the derived AGN bolometric luminosity function with the
observed one. While we find for the most part a very good agreement between
predicted and observed BH properties, the semi-analytic model underestimates
the number density of luminous AGN at high redshifts, independently of the
adopted Eddington factor and accretion efficiency. However, an agreement with
the observations is possible within the framework of our model, provided it is
assumed that the cold gas fraction accreted by BHs at high redshifts is larger
than at low redshifts.Comment: 15 pages, 7 figures, MNRAS submitte
Lifestyle behaviours of young adult survivors of childhood cancer
This cross-sectional study collected baseline data on the health behaviours of a large population of survivors of childhood cancer in the UK, aged 18â30 years, compared with those of sex- and age-matched controls. Data from 178 young adult survivors of childhood cancer, diagnosed and treated at Bristol Children's Hospital, 184 peers from the survivors' GP practices and 67 siblings were collected by postal questionnaire. Conditional logistic regression analysis showed that, for matched sets of survivors and controls, survivors of a variety of childhood cancers reported lower levels of alcohol consumption (P=0.005), lower levels of cigarette smoking (P=0.027) and lower levels of recreational drug use (P=0.001) than controls. Analysis of matched sets of survivors and siblings showed similar trends but no significant differences. A health behaviour index for each participant was constructed from the data collected on five key health behaviours which influence future health status. Comparison of the means for each case group showed that survivors of childhood cancer were leading healthier lives than controls or siblings. This finding was expressed most clearly as the difference in the means of the health behaviour index for each case group, derived from five health behaviours (one-way ANOVA, P<0.001)
On the cosmic evolution of the scaling relations between black holes and their host galaxies: Broad Line AGN in the zCOSMOS survey
(Abriged) We report on the measurement of the rest frame K-band luminosity
and total stellar mass of the hosts of 89 broad line Active Galactic Nuclei
detected in the zCOSMOS survey in the redshift range 1<z<2.2. The unprecedented
multiwavelength coverage of the survey field allows us to disentangle the
emission of the host galaxy from that of the nuclear black hole in their
Spectral Energy Distributions. We derive an estimate of black hole masses
through the analysis of the broad Mg II emission lines observed in the
medium-resolution spectra taken with VIMOS/VLT as part of the zCOSMOS project.
We found that, as compared to the local value, the average black hole to host
galaxy mass ratio appears to evolve positively with redshift, with a best fit
evolution of the form (1+z)^{0.68 \pm0.12 +0.6 -0.3}, where the large
asymmetric systematic errors stem from the uncertainties in the choice of IMF,
in the calibration of the virial relation used to estimate BH masses and in the
mean QSO SED adopted. A thorough analysis of observational biases induced by
intrinsic scatter in the scaling relations reinforces the conclusion that an
evolution of the MBH-M* relation must ensue for actively growing black holes at
early times: either its overall normalization, or its intrinsic scatter (or
both) appear to increase with redshift. This can be interpreted as signature of
either a more rapid growth of supermassive black holes at high redshift, a
change of structural properties of AGN hosts at earlier times, or a significant
mismatch between the typical growth times of nuclear black holes and host
galaxies.Comment: 47 pages, 8 figures. Accepted for publication in Ap
Female Membership in the Black-Society Style Criminal Organizations: Evidence From a Female Prison in China
From the 1970s onwards, womenâs participation in gangs in the mainstream Western social contexts has been increasingly researched. However, the experiences of women in other cultural settings are rarely discussed. This qualitative study focuses on female members of the black-society style criminal organizations (BSSCO) in China. It starts with reviewing literature on female gang membership and on BSSCO so as to locate its discussions in the international criminological framework. This is followed by a methodology section, and then it analyses the empirical findings. This article seeks to provide some theoretical insights into the construction of female criminal membership in broader social contexts
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