9,847 research outputs found
Efficacy of property marking: police identification of stolen property
Property marking, as a situational crime prevention technique, has found to be largely ineffectual in the reduction of property theft, although past studies have not considered the role property marking as an aid to the return of stolen or lost property. However, automotive identification and some studies have found that in some cases property marking is effective. Furthermore, many crime prevention groups focus on property marking as a means to reduce crime and the fear of crime. Therefore, the study investigated the processes of lost, stolen and seized goods by law enforcement personnel. The study undertook a qualitative analysis of law enforcement property identification process, including a documentary analysis of procedures and practitioner interviews for content-thematic analysis. The study found that the use of manufacturer serial numbers was the initial line of investigative enquiry. Limiting factors were technical capability to find and use covert property markings. The successful implementation of a code of best practice or standardisation in the recording of serial numbers, and the availability of the community to quickly and easily record their property may have a significant effect in the reduction of property crimes; due to the perceived increase of risk and potential reduction of reward to the offender
Large Scale Baryon Isocurvature Inhomogeneities
Big bang nucleosynthesis constraints on baryon isocurvature perturbations are
determined. A simple model ignoring the effects of the scale of the
perturbations is first reviewed. This model is then extended to test the claim
that large amplitude perturbations will collapse, forming compact objects and
preventing their baryons from contributing to the observed baryon density. It
is found that baryon isocurvature perturbations are constrained to provide only
a slight increase in the density of baryons in the universe over the standard
homogeneous model. In particular it is found that models which rely on power
laws and the random phase approximation for the power spectrum are incompatible
with big bang nucleosynthesis unless an {\em ad hoc}, small scale cutoff is
included.Comment: 11pages + 8figures, LaTeX (2.09), postscript figures available via
anonymous ftp from oddjob.uchicago.edu:/ftp/ibbn/fig?.ps where ?=1-8 or via
email from [email protected], Fermilab-Pub-94/???-A and UMN-TH-1307/9
GW170817 Most Likely Made a Black Hole
There are two outstanding issues regarding the neutron-star merger event
GW170817: the nature of the compact remnant and the interstellar shock. The
mass of the remnant of GW170817, 2.7 , implies the remnant could
be either a massive, rotating, neutron star, or a black hole. We report Chandra
Director's Discretionary Time observations made in 2017 December and 2018
January, and we reanalyze earlier observations from 2017 August and 2017
September, in order to address these unresolved issues. We estimate the X-ray
flux from a neutron star remnant and compare that to the measured X-ray flux.
If we assume that the spin-down luminosity of any putative neutron star is
converted to pulsar wind nebula X-ray emission in the 0.5-8 keV band with an
efficiency of , for a dipole magnetic field with G
< < G, a rising X-ray signal would result and would be brighter
than that observed by day 107, we therefore conclude that the remnant of
GW170817 is most likely a black hole. Independent of any assumptions of X-ray
efficiency, however, if the remnant is a rapidly-rotating, magnetized, neutron
star, the total energy in the external shock should rise by a factor
(to erg) after a few years, therefore, Chandra
observations over the next year or two that do not show substantial brightening
will rule out such a remnant. The same observations can distinguish between two
different models for the relativistic outflow, either an angular or radially
varying structure.Comment: 10 pages, 4 figures, accepted to ApJ
Assessing Alternatives for Directional Detection of a WIMP Halo
The future of direct terrestrial WIMP detection lies on two fronts: new, much
larger low background detectors sensitive to energy deposition, and detectors
with directional sensitivity. The former can large range of WIMP parameter
space using well tested technology while the latter may be necessary if one is
to disentangle particle physics parameters from astrophysical halo parameters.
Because directional detectors will be quite difficult to construct it is
worthwhile exploring in advance generally which experimental features will
yield the greatest benefits at the lowest costs. We examine the sensitivity of
directional detectors with varying angular tracking resolution with and without
the ability to distinguish forward versus backward recoils, and compare these
to the sensitivity of a detector where the track is projected onto a
two-dimensional plane. The latter detector regardless of where it is placed on
the Earth, can be oriented to produce a significantly better discrimination
signal than a 3D detector without this capability, and with sensitivity within
a factor of 2 of a full 3D tracking detector. Required event rates to
distinguish signals from backgrounds for a simple isothermal halo range from
the low teens in the best case to many thousands in the worst.Comment: 4 pages, including 2 figues and 2 tables, submitted to PR
Understanding Adolescent Intentions to Smoke: An Examination of Relationships Among Social Influence, Prior Trial Behavior, and Antitobacco Campaign Advertising
Telephone interviews were conducted with more than 900 adolescents aged 12 to 18 as part of a multimillion dollar, statewide, antitobacco advertising campaign. The interviews addressed two primary questions: (1) Do counter-advertising campaign attitudes directly affect antismoking beliefs and intent in a manner similar to those of conventional advertisements? and (2) Can advertising campaign attitudes have a stronger effect on beliefs and intent for adolescents with prior smoking behavior and for adolescents exposed to social influence (i.e., friends, siblings, or adult smoker in the home)? The authors\u27 findings show that advertising campaign attitudes, prior trial behavior, and social influence all directly affect antismoking beliefs and that advertising campaign attitudes interact with prior trial behavior to strengthen antismoking beliefs. The results indicate that attitudes related to the campaign, prior trial behavior, and social influence directly influence intent, and advertising campaign attitudes interact with social influence and prior trial behavior to attenuate adolescent intent to smoke. In addition, the effect of advertising campaign attitudes in attenuating social influence and prior trial behavior effects on adolescent intent to smoke persists even when the authors account for strongly held beliefs about smoking. The authors discuss implications for countermarketing communications and the design and understanding of future antismoking campaigns
Time-resolved velocity map imaging of methyl elimination from photoexcited anisole
To date, H-atom elimination from heteroaromatic molecules following UV excitation has been extensively studied, with the focus on key biological molecules such as chromophores of DNA bases and amino acids. Extending these studies to look at elimination of other non-hydride photoproducts is essential in creating a more complete picture of the photochemistry of these biomolecules in the gas-phase. To this effect, CH3 elimination in anisole has been studied using time resolved velocity map imaging (TR-VMI) for the first time, providing both time and energy information on the dynamics following photoexcitation at 200 nm. The extra dimension of energy afforded by these measurements has enabled us to address the role of πσ* states in the excited state dynamics of anisole as compared to the hydride counterpart (phenol), providing strong evidence to suggest that only CH3 fragments eliminated with high kinetic energy are due to direct dissociation involving a 1πσ* state. These measurements also suggest that indirect mechanisms such as statistical unimolecular decay could be contributing to the dynamics at much longer times
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