3,860 research outputs found
The diffusion of police innovation: A case study of problem-oriented policing in England and Wales
There is significant evidence demonstrating that when done well, problem-oriented policing is associated with meaningful reductions in crime and public safety concerns. And yet, history shows that the implementation and delivery of problem-oriented policing is challenging, and that police organisations have generally not adopted it and even when they try to it is often rejected over time. This article draws on the concept of ‘diffusion of innovation’ (Rogers, E. (2003) Diffusion of Innovations, 5th edn. New York: Free Press) to unpick aspects of the processes through which problem-oriented policing has been adopted or otherwise among police forces in England and Wales. This article shows how factors related to the nature of problem-oriented policing – notably its incompatibility with prevailing norms and values of the police service, its complexity and unobservability – have influenced its adoption. Implications are also discussed
The X-Ray Concentration-Virial Mass Relation
We present the concentration (c)-virial mass (M) relation of 39 galaxy
systems ranging in mass from individual early-type galaxies up to the most
massive galaxy clusters, (0.06-20) x 10^{14} M_sun. We selected for analysis
the most relaxed systems possessing the highest quality data currently
available in the Chandra and XMM public data archives. A power-law model fitted
to the X-ray c-M relation requires at high significance (6.6 sigma) that c
decreases with increasing M, which is a general feature of CDM models. The
median and scatter of the c-M relation produced by the flat, concordance LCDM
model (Omega_m=0.3, sigma_8=0.9) agrees with the X-ray data provided the sample
is comprised of the most relaxed, early forming systems, which is consistent
with our selection criteria. Holding the rest of the cosmological parameters
fixed to those in the concordance model the c-M relation requires 0.76< sigma_8
<1.07 (99% conf.), assuming a 10% upward bias in the concentrations for early
forming systems. The tilted, low-sigma_8 model suggested by a new WMAP analysis
is rejected at 99.99% confidence, but a model with the same tilt and
normalization can be reconciled with the X-ray data by increasing the dark
energy equation of state parameter to w ~ -0.8. When imposing the additional
constraint of the tight relation between sigma_8 and Omega_m from studies of
cluster abundances, the X-ray c-M relation excludes (>99% conf.) both open CDM
models and flat CDM models with Omega_m ~1. This result provides novel evidence
for a flat, low-Omega_m universe with dark energy using observations only in
the local (z << 1) universe. Possible systematic errors in the X-ray mass
measurements of a magnitude ~10% suggested by CDM simulations do not change our
conclusions.Comment: Accepted for Publication in ApJ; 13 pages, 4 figures; minor
clarifications and updates; correlation coefficients corrected in Table 1
(correct values were used in the analysis in previous versions); conclusions
unchange
The Universal Stellar Mass-Stellar Metallicity Relation for Dwarf Galaxies
We present spectroscopic metallicities of individual stars in seven gas-rich dwarf irregular galaxies (dIrrs), and we show that dIrrs obey the same mass-metallicity relation as the dwarf spheroidal (dSph) satellites of both the Milky Way and M31: Z_* ∝ M_*^(0.30±0.02). The uniformity of the relation is in contradiction to previous estimates of metallicity based on photometry. This relationship is roughly continuous with the stellar mass-stellar metallicity relation for galaxies as massive as M_* = 10^(12) M_☉. Although the average metallicities of dwarf galaxies depend only on stellar mass, the shapes of their metallicity distributions depend on galaxy type. The metallicity distributions of dIrrs resemble simple, leaky box chemical evolution models, whereas dSphs require an additional parameter, such as gas accretion, to explain the shapes of their metallicity distributions. Furthermore, the metallicity distributions of the more luminous dSphs have sharp, metal-rich cut-offs that are consistent with the sudden truncation of star formation due to ram pressure stripping
Segue 2: The Least Massive Galaxy
Segue 2, discovered by Belokurov et al., is a galaxy with a luminosity of only 900 L_☉. We present Keck/DEIMOS spectroscopy of 25 members of Segue 2—a threefold increase in spectroscopic sample size. The velocity dispersion is too small to be measured with our data. The upper limit with 90% (95%) confidence is σ_v < 2.2 (2.6) km s^(–1), the most stringent limit for any galaxy. The corresponding limit on the mass within the three-dimensional half-light radius (46 pc) is M_(1/2) < 1.5 (2.1) × 10^5 M_☉. Segue 2 is the least massive galaxy known. We identify Segue 2 as a galaxy rather than a star cluster based on the wide dispersion in [Fe/H] (from –2.85 to –1.33) among the member stars. The stars' [α/Fe] ratios decline with increasing [Fe/H], indicating that Segue 2 retained Type Ia supernova ejecta despite its presently small mass and that star formation lasted for at least 100 Myr. The mean metallicity, 〈[Fe/H]〉 = -2.22 ± 0.13 (about the same as the Ursa Minor galaxy, 330 times more luminous than Segue 2), is higher than expected from the luminosity-metallicity relation defined by more luminous dwarf galaxy satellites of the Milky Way. Segue 2 may be the barest remnant of a tidally stripped, Ursa Minor-sized galaxy. If so, it is the best example of an ultra-faint dwarf galaxy that came to be ultra-faint through tidal stripping. Alternatively, Segue 2 could have been born in a very low mass dark matter subhalo (v_(max) < 10 km s^(–1)), below the atomic hydrogen cooling limit
New graduate doctors' preparedness for practice: A multistakeholder, multicentre narrative study
This is the final version. Available on open access from BMJ Publishing Group via the link in this recordData sharing statement The raw data for this research consist of audio-recordings of narrative interviews and audio diaries. The principal investigator (Professor Lynn V Monrouxe) has access to this specific data set, including audio-recordings of interviews and interview transcripts, in addition to participant contact details and signed consent forms. All authors have access to anonymised data from this set. All data are stored securely on password-protected and encrypted computers. Participants have not given their permission for data sharing outside the research group. Thus, no additional data are available.Objective While previous studies have begun to explore newly graduated junior doctors' preparedness for practice, findings are largely based on simplistic survey data or perceptions of newly graduated junior doctors and their clinical supervisors alone. This study explores, in a deeper manner, multiple stakeholders' conceptualisations of what it means to be prepared for practice and their perceptions about newly graduated junior doctors' preparedness (or unpreparedness) using innovative qualitative methods. Design A multistakeholder, multicentre qualitative study including narrative interviews and longitudinal audio diaries. Setting Four UK settings: England, Northern Ireland, Scotland and Wales. Participants Eight stakeholder groups comprising n=185 participants engaged in 101 narrative interviews (27 group and 84 individual). Twenty-six junior doctors in their first year postgraduation also provided audio diaries over a 3-month period. Results We identified 2186 narratives across all participants (506 classified as 'prepared', 663 as 'unprepared', 951 as 'general'). Seven themes were identified; this paper focuses on two themes pertinent to our research questions: (1) explicit conceptualisations of preparedness for practice; and (2) newly graduated junior doctors' preparedness for the General Medical Council's (GMC) outcomes for graduates. Stakeholders' conceptualisations of preparedness for practice included short-term (hitting the ground running) and long-term preparedness, alongside being prepared for practical and emotional aspects. Stakeholders' perceptions of medical graduates' preparedness for practice varied across different GMC outcomes for graduates (eg, Doctor as Scholar and Scientist, as Practitioner, as Professional) and across stakeholders (eg, newly graduated doctors sometimes perceived themselves as prepared but others did not). Conclusion Our narrative findings highlight the complexities and nuances surrounding new medical graduates' preparedness for practice. We encourage stakeholders to develop a shared understanding (and realistic expectations) of new medical graduates' preparedness. We invite medical school leaders to increase the proportion of time that medical students spend participating meaningfully in multiprofessional teams during workplace learning.General Medical Counci
Problem-oriented policing in England and Wales: barriers and facilitators
Evidence shows that the application of problem-oriented policing can be effective in reducing a wide range of crime and public safety issues, but that the approach is challenging to implement and sustain. This article examines police perceptions and experiences regarding organisational barriers to and facilitators of the implementation and delivery of problem-oriented policing. Drawing on surveys of (n = 4141) and interviews with (n = 86) police personnel from 19 police forces in England and Wales, we identify five key barriers and facilitators to problem-oriented policing: leadership and governance, capacity, organisational structures and infrastructure, partnership working and organisational culture. These factors provide important indicators for what police organisations need to do, or need to avoid, if they are to successfully embed and deliver problem-oriented policing. The article generates critical information about the processes that drive change in police organisations and offers recommendations for police managers who may wish to implement or develop problem-oriented policing. The paper also proposes a research agenda aimed at addressing evidence gaps in our understanding of the implementation and sustenance of problem-oriented policing
Klein-Gordon Solutions on Non-Globally Hyperbolic Standard Static Spacetimes
We construct a class of solutions to the Cauchy problem of the Klein-Gordon
equation on any standard static spacetime. Specifically, we have constructed
solutions to the Cauchy problem based on any self-adjoint extension (satisfying
a technical condition: "acceptability") of (some variant of) the
Laplace-Beltrami operator defined on test functions in an -space of the
static hypersurface. The proof of the existence of this construction completes
and extends work originally done by Wald. Further results include the
uniqueness of these solutions, their support properties, the construction of
the space of solutions and the energy and symplectic form on this space, an
analysis of certain symmetries on the space of solutions and of various
examples of this method, including the construction of a non-bounded below
acceptable self-adjoint extension generating the dynamics
Strong Influence of the diffuse component on the lattice dynamics in Pb(MgNb)O
The temperature and zone dependence of the lattice dynamics in
Pb(MgNb)O is characterized using neutron inelastic
scattering. A strong correlation between the diffuse and phonon scattering is
measured. The lattice dynamics in Brillouin zones where the diffuse scattering
is strong is observed to display qualitatively different behavior than those
zones where the diffuse scattering is weak. In the (220) and (200) zones, where
there is a weak diffuse component, the dynamics are well described by coupled
harmonic oscillators. Compared with SrTiO, the coupling is weak and
isotropic, resulting in only a small transfer of spectral weight from one mode
to another. A comparison of the scattering in these zones to the (110) zone,
where a strong diffuse component is present, reveals a strong coupling of the
diffuse (or central) component to the acoustic mode. We speculate that the
coupling to the central peak is the reason for several recent conflicting
interpretations of the lattice dynamics based on data from zones with a strong
diffuse component.Comment: 7 pages, 7 figure
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