1,779 research outputs found
Enhancing the work of the Islington Integrated Gangs Team: A pilot study on the response to serious youth violence in Islington
This report is the result of research conducted by the Centre for City Criminology at City, University of London, in partnership with Islington’s Integrated Gangs Team (IGT) and the Metropolitan Police Service (MPS). The research was co-funded by MPS and the School of Arts and Social Sciences, City, University of London. Following a collaborative research event in October 2017, City Criminologists were commissioned to carry out a small-scale research project to capture the work of the IGT and to make recommendations regarding its operations, coherence, effectiveness and sustainability. The research team conducted semi-structured interviews over several months with 23 practitioners across the services that constitute the IGT. This report presents the findings and recommendations
Magnetohydrodynamics dynamical relaxation of coronal magnetic fields. I. Parallel untwisted magnetic fields in 2D
Context. For the last thirty years, most of the studies on the relaxation of
stressed magnetic fields in the solar environment have onlyconsidered the
Lorentz force, neglecting plasma contributions, and therefore, limiting every
equilibrium to that of a force-free field. Aims. Here we begin a study of the
non-resistive evolution of finite beta plasmas and their relaxation to
magnetohydrostatic states, where magnetic forces are balanced by
plasma-pressure gradients, by using a simple 2D scenario involving a
hydromagnetic disturbance to a uniform magnetic field. The final equilibrium
state is predicted as a function of the initial disturbances, with aims to
demonstrate what happens to the plasma during the relaxation process and to see
what effects it has on the final equilibrium state. Methods. A set of numerical
experiments are run using a full MHD code, with the relaxation driven by
magnetoacoustic waves damped by viscous effects. The numerical results are
compared with analytical calculations made within the linear regime, in which
the whole process must remain adiabatic. Particular attention is paid to the
thermodynamic behaviour of the plasma during the relaxation. Results. The
analytical predictions for the final non force-free equilibrium depend only on
the initial perturbations and the total pressure of the system. It is found
that these predictions hold surprisingly well even for amplitudes of the
perturbation far outside the linear regime. Conclusions. Including the effects
of a finite plasma beta in relaxation experiments leads to significant
differences from the force-free case
RRATs: New Discoveries, Timing Solutions & Musings
We describe observations of Rotating RAdio Transients (RRATs) that were
discovered in a re-analysis of the Parkes Multi-beam Pulsar Survey (PMPS). The
sources have now been monitored for sufficiently long to obtain seven new
coherent timing solutions, to make a total of 14 now known. Furthermore we
announce the discovery of 7 new transient sources, one of which may be
extragalactic in origin (with ) and would then be a second example of
the so-called `Lorimer burst'. The timing solutions allow us to infer neutron
star characteristics such as energy-loss rate, magnetic field strength and
evolutionary timescales, as well as facilitating multi-wavelength followup by
providing accurate astrometry. All of this enables us to consider the question
of whether or not RRATs are in any way special, i.e. a distinct and separate
population of neutron stars, as has been previously suggested. We see no reason
to consider 'RRAT' as anything other than a detection label, the subject of a
selection effect in the parameter space searched. However, single-pulse
searches can be utilised to great effect to identify pulsars difficult, or
impossible, to find by other means, in particular those with long-periods (half
of the PMPS RRATs have periods greater than 4 seconds), high-magnetic field
strengths ( G) and pulsars approaching the 'death valley'.
The detailed nulling properties of such pulsars are unknown but the mounting
evidence suggests a broad range of behaviour in the pulsar population. The
group of RRATs fit in to the picture where pulsar magnetospheres switch between
stable configurations.Comment: accepted for publication in MNRAS, 17 pages, 7 figures, 3 table
Chemodynamics of Compact Stellar Systems in NGC 5128: How similar are Globular Clusters, Ultra-Compact Dwarfs, and Dwarf Galaxies?
Velocity dispersion measurements are presented for luminous GCs in NGC 5128
derived from high-res. UVES spectra. The measurements are made with the pPXF
code that parametrically recovers line-of-sight velocity dispersions. Combining
the measured velocity dispersions with surface photometry and structural
parameter data from HST enables both dynamical masses and M/L ratios to be
derived. The fundamental plane relations of these clusters are investigated in
order to fill the apparent gap between the relations of Local Group GCs and
more massive early-type galaxies. It is found that the properties of these
massive stellar systems match those of nuclear clusters in dwarf elliptical
galaxies and UCDs better than those of Local Group GCs, and that all objects
share similarly old (>8 Gyr) ages, suggesting a possible link between the
formation and evolution of dE,Ns, UCDs and massive GCs. We find a very steep
correlation between dynamical (M/L) ratio and dynamical mass of the form
(M/L)_dyn ~ M_dyn^(0.24+/-0.02) above M_dyn = 2x10^6 Msol. Formation scenarios
are investigated with a chemical abundance analysis using absorption line
strengths calibrated to the Lick/IDS index system. The results lend support to
two scenarios contained within a single general formation scheme. Old, massive,
super-solar [alpha/Fe] systems are formed on short (<100 Myr) timescales
through the merging of single-collapse GCs which themselves are formed within
single, giant molecular clouds. More intermediate- and old-aged (~3-10 Gyr),
solar- to sub-solar [alpha/Fe] systems are formed on much longer (~Gyr)
timescales through the stripping of dE,Ns in the 10^13-10^15 Msol potential
wells of massive galaxies and galaxy clusters.Comment: 12 pages (ApJ style) with 11 figures and 7 tables, accepted for
publication in Ap
Discovery of 10 pulsars in an Arecibo drift-scan survey
We present the results of a 430-MHz survey for pulsars conducted during the
upgrade to the 305-m Arecibo radio telescope. Our survey covered a total of
1147 square degrees of sky using a drift-scan technique. We detected 33
pulsars, 10 of which were not known prior to the survey observations. The
highlight of the new discoveries is PSR J0407+1607, which has a spin period of
25.7 ms, a characteristic age of 1.5 Gyr and is in a 1.8-yr orbit about a
low-mass (>0.2 Msun) companion. The long orbital period and small eccentricity
(e = 0.0009) make the binary system an important new addition to the ensemble
of binary pulsars suitable to test for violations of the strong equivalence
principle. We also report on our initially unsuccessful attempts to detect
optically the companion to J0407+1607 which imply that its absolute visual
magnitude is > 12.1. If, as expected on evolutionary grounds, the companion is
an He white dwarf, our non-detection imples a cooling age of least 1 Gyr.Comment: 8 pages, 3 figures, accepted for publication in MNRA
The three dimensions of online child pornography offending
The internet has opened up opportunities for non-contact sex offending, such as the viewing of child pornography. This paper proposes a model for the classification of child pornography offenders as an aid for their assessment and treatment, deducted from empirical studies and existing
typologies for child pornography offenders. Different subgroups of child pornography offenders may be described according to three dimensions: (1) type of offending, (2) the motivation behind child pornography offending and (3) the situational and social engagement in the offending behaviour. Distinct pathways of child pornography offending can be identified, related to differing criminogenic
needs, severity of offending, and appropriate assessment and treatment strategies for the offenders
Surveying the Dynamic Radio Sky with the Long Wavelength Demonstrator Array
This paper presents a search for radio transients at a frequency of 73.8 MHz
(4 m wavelength) using the all-sky imaging capabilities of the Long Wavelength
Demonstrator Array (LWDA). The LWDA was a 16-dipole phased array telescope,
located on the site of the Very Large Array in New Mexico. The field of view of
the individual dipoles was essentially the entire sky, and the number of
dipoles was sufficiently small that a simple software correlator could be used
to make all-sky images. From 2006 October to 2007 February, we conducted an
all-sky transient search program, acquiring a total of 106 hr of data; the time
sampling varied, being 5 minutes at the start of the program and improving to 2
minutes by the end of the program. We were able to detect solar flares, and in
a special-purpose mode, radio reflections from ionized meteor trails during the
2006 Leonid meteor shower. We detected no transients originating outside of the
solar system above a flux density limit of 500 Jy, equivalent to a limit of no
more than about 10^{-2} events/yr/deg^2, having a pulse energy density >~ 1.5 x
10^{-20} J/m^2/Hz at 73.8 MHz for pulse widths of about 300 s. This event rate
is comparable to that determined from previous all-sky transient searches, but
at a lower frequency than most previous all-sky searches. We believe that the
LWDA illustrates how an all-sky imaging mode could be a useful operational
model for low-frequency instruments such as the Low Frequency Array, the Long
Wavelength Array station, the low-frequency component of the Square Kilometre
Array, and potentially the Lunar Radio Array.Comment: 20 pages; accepted for publication in A
Labelling, Deviance and Media
Labelling theory is a perspective that emerged as a distinctive approach to criminology during the 1960s, and was a major seedbed of the radical and critical perspectives that became prominent in the 1970s. It represented the highpoint of an epistemological shift within the social sciences away from positivism – which had dominated criminological enquiry since the late-1800s – and toward an altogether more relativistic stance on the categories and concepts of crime and control. It inspired a huge amount of work throughout the 1960s and 1970s, and still resonates powerfully today. This short chapter maps out some of the ways in which labelling, deviance, media and justice interact at the levels of definition and process. It presents an overview and analysis of key mediatised labelling processes, such as the highly influential concept of moral panics. It discusses how the interconnections between labelling, crime and criminal justice are changing in a context of technological development, cultural change and media proliferation. The conclusion offers an assessment and evaluation of labelling theory’s long-term impact on criminology
SARS-CoV-2 infection and COVID-19 vaccination rates in pregnant women in Scotland
Population-level data on COVID-19 vaccine uptake in pregnancy and SARS-CoV-2 infection outcomes are lacking. We describe COVID-19 vaccine uptake and SARS-CoV-2 infection in pregnant women in Scotland, using whole-population data from a national, prospective cohort. Between the start of a COVID-19 vaccine program in Scotland, on 8 December 2020 and 31 October 2021, 25,917 COVID-19 vaccinations were given to 18,457 pregnant women. Vaccine coverage was substantially lower in pregnant women than in the general female population of 18-44 years; 32.3% of women giving birth in October 2021 had two doses of vaccine compared to 77.4% in all women. The extended perinatal mortality rate for women who gave birth within 28 d of a COVID-19 diagnosis was 22.6 per 1,000 births (95% CI 12.9-38.5; pandemic background rate 5.6 per 1,000 births; 452 out of 80,456; 95% CI 5.1-6.2). Overall, 77.4% (3,833 out of 4,950; 95% CI 76.2-78.6) of SARS-CoV-2 infections, 90.9% (748 out of 823; 95% CI 88.7-92.7) of SARS-CoV-2 associated with hospital admission and 98% (102 out of 104; 95% CI 92.5-99.7) of SARS-CoV-2 associated with critical care admission, as well as all baby deaths, occurred in pregnant women who were unvaccinated at the time of COVID-19 diagnosis. Addressing low vaccine uptake rates in pregnant women is imperative to protect the health of women and babies in the ongoing pandemic. [Abstract copyright: © 2022. The Author(s).
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