878 research outputs found
Denying humanness to victims: How gang members justify violent behavior
The high prevalence of violent offending amongst gang-involved youth has been established in the literature. Yet the underlying psychological mechanisms that enable youth to engage in such acts of violence remain unclear. 189 young people were recruited from areas in London, UK, known for their gang activity. We found that gang members, in comparison to non-gang youth, described the groups they belong to as having recognized leaders, specific rules and codes, initiation rituals, and special clothing. Gang members were also more likely than non-gang youth to engage in violent behavior and endorse moral disengagement strategies (i.e., moral justification, euphemistic language, advantageous comparison, displacement of responsibility, attribution of blame, and dehumanization). Finally, we found that dehumanizing victims partially mediated the relationship between gang membership and violent behavior. These findings highlight the effects of groups at the individual level and an underlying psychological mechanism that explains, in part, how gang members engage in violence
Time-dependent Hamiltonian estimation for Doppler velocimetry of trapped ions
The time evolution of a closed quantum system is connected to its Hamiltonian
through Schroedinger's equation. The ability to estimate the Hamiltonian is
critical to our understanding of quantum systems, and allows optimization of
control. Though spectroscopic methods allow time-independent Hamiltonians to be
recovered, for time-dependent Hamiltonians this task is more challenging. Here,
using a single trapped ion, we experimentally demonstrate a method for
estimating a time-dependent Hamiltonian of a single qubit. The method involves
measuring the time evolution of the qubit in a fixed basis as a function of a
time-independent offset term added to the Hamiltonian. In our system the
initially unknown Hamiltonian arises from transporting an ion through a static,
near-resonant laser beam. Hamiltonian estimation allows us to estimate the
spatial dependence of the laser beam intensity and the ion's velocity as a
function of time. This work is of direct value in optimizing transport
operations and transport-based gates in scalable trapped ion quantum
information processing, while the estimation technique is general enough that
it can be applied to other quantum systems, aiding the pursuit of high
operational fidelities in quantum control.Comment: 10 pages, 8 figure
Strong quantum violation of the gravitational weak equivalence principle by a non-Gaussian wave-packet
The weak equivalence principle of gravity is examined at the quantum level in
two ways. First, the position detection probabilities of particles described by
a non-Gaussian wave-packet projected upwards against gravity around the
classical turning point and also around the point of initial projection are
calculated. These probabilities exhibit mass-dependence at both these points,
thereby reflecting the quantum violation of the weak equivalence principle.
Secondly, the mean arrival time of freely falling particles is calculated using
the quantum probability current, which also turns out to be mass dependent.
Such a mass-dependence is shown to be enhanced by increasing the
non-Gaussianity parameter of the wave packet, thus signifying a stronger
violation of the weak equivalence principle through a greater departure from
Gaussianity of the initial wave packet. The mass-dependence of both the
position detection probabilities and the mean arrival time vanish in the limit
of large mass. Thus, compatibility between the weak equivalence principle and
quantum mechanics is recovered in the macroscopic limit of the latter. A
selection of Bohm trajectories is exhibited to illustrate these features in the
free fall case.Comment: 11 pages, 7 figure
Dangerous drugs, dangerous mothers: Gender, responsibility and the problematisation of parental substance use
If, as many would have it, the ‘drugs problem’ is among the more perilous and uncompromising challenges of our times, parental substance misuse represents one of its most insidious expressions. The past 15 years has seen the ‘hidden harms’ experienced by the children of drug users emerge as a principal concern for national policy actors and local service provision. However, there has been relatively little critique of the assumptions and epistemological foundations underscoring this policy shift, or of the preoccupation with the ‘family’ in drug policy in general. Through examination of seminal policy documents relating to parental substance misuse, and using Carol Bacchi’s ‘What’s the Problem Represented to Be?’ (WPR) approach, this article attends more closely to the formulation of parental drug use as a significant policy problem, and to the family as a principal site for the constitution of drug harms
Zeno Dynamics of von Neumann Algebras
The dynamical quantum Zeno effect is studied in the context of von Neumann
algebras. We identify a localized subalgebra on which the Zeno dynamics acts by
automorphisms. The Zeno dynamics coincides with the modular dynamics of that
subalgebra, if an additional assumption is satisfied. This relates the modular
operator of that subalgebra to the modular operator of the original algebra by
a variant of the Kato-Lie-Trotter product formula.Comment: Revised version; further typos corrected; 9 pages, AMSLaTe
Real clocks and the Zeno effect
Real clocks are not perfect. This must have an effect in our predictions for
the behaviour of a quantum system, an effect for which we present a unified
description encompassing several previous proposals. We study the relevance of
clock errors in the Zeno effect, and find that generically no Zeno effect can
be present (in such a way that there is no contradiction with currently
available experimental data). We further observe that, within the class of
stochasticities in time addressed here, there is no modification in emission
lineshapes.Comment: 12 a4 pages, no figure
Putting victims first? : a critique of Coalition anti-social behaviour policy
Anti-social behaviour (ASB) policy was not pursued by the Conservative–Liberal Democrat Coalition government with the same vigour as their New Labour predecessors. Where developments did take place a clear shift in emphasis was apparent, with the needs of ASB victims elevated to the forefront of policy. This article critically appraises two major developments that showcase the Coalition government’s attempts to overhaul ASB policy to ‘put victims first’, namely: the changes to call handling and case management processes, and the Community Trigger, which forces the authorities to review their responses to complaints of ASB in circumstances where victims feel they have been ignored. These particular policies aim to prioritise victims’ needs; however, it is argued the new victim-focus: is diluted by competing Coalition ASB agendas, demonstrates little connection between rhetoric and reality, provides limited redress for all victims and fails to coalesce with established attempts to tackle perpetrators of ASB
Reflection and Transmission in a Neutron-Spin Test of the Quantum Zeno Effect
The dynamics of a quantum system undergoing frequent "measurements", leading
to the so-called quantum Zeno effect, is examined on the basis of a
neutron-spin experiment recently proposed for its demonstration. When the
spatial degrees of freedom are duely taken into account, neutron-reflection
effects become very important and may lead to an evolution which is totally
different from the ideal case.Comment: 26 pages, 6 figure
Incidence and Prevalence of Unrecognized Myocardial Infarction in People With Diabetes: A substudy of the Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of Glycemia in Diabetes (RECORD) study
<p>OBJECTIVE: To examine the prevalence and incidence of unrecognized myocardial infarction in a contemporary population with type 2 diabetes.</p>
<p>RESEARCH DESIGN AND METHODS: We performed a retrospective analysis of the electrocardiograms (ECGs) recorded at baseline and after 2 years for the first 1,004 type 2 diabetic individuals to be randomized in the Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of Glycemia in Diabetes (RECORD) study.</p>
<p>RESULTS: ECGs suitable for analysis were obtained from 669 participants. The prevalence of unrecognized Q-wave myocardial infarction at baseline was 1.9% (n = 13). The incidence of unrecognized Q-wave myocardial infarction at the end of 2 years of follow-up was 1.5/1,000-person-years (n = 2). One-third (13 of 39) of prevalent and one-quarter (2 of 8) of incident myocardial infarctions were unrecognized.</p>
<p>CONCLUSIONS: Although the prevalence and incidence of myocardial infarction was low, unrecognized Q-wave myocardial infarctions made up a substantial proportion of all events.</p>
Young people, crime and school exclusion: a case of some surprises
During the 1990s the number of young people being permanently excluded from schools in England and Wales increased dramatically from 2,910 (1990/91) to a peak of 12,700 (1996/97). Coinciding with this rise was a resurgence of the debate centring on lawless and delinquent youth. With the publication of Young People and Crime (Graham and Bowling 1995) and Misspent Youth (Audit Commission 1996) the 'common sense assumption' that exclusion from school inexorably promoted crime received wide support, with the school excludee portrayed as another latter day 'folk devil'. This article explores the link between school exclusion and juvenile crime, and offers some key findings from a research study undertaken with 56 young people who had experience of being excluded from school. Self-report interview questions reveal that whilst 40 of the young people had offended, 90% (36) reported that the onset of their offending commenced prior to their first exclusion. Moreover, 50 (89.2% of the total number of young people in the sample), stated that they were no more likely to offend subsequent to being excluded and 31 (55.4%) stated that they were less likely to offend during their exclusion period. Often, this was because on being excluded, they were 'grounded' by their parents
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