5,692 research outputs found
The international development of the ‘Social Norms’ approach to drug education and prevention
Binge drinking has sparked considerable interest and concern. However despite this interest little is known about the lay understanding of binge drinking and whether there are differences in understanding by gender, age and level of deprivation. Aims: This study investigated the beliefs and attitudes of a sample in the Inverclyde area to binge drinking. Methods: Using both cluster and quota sampling, 586 subjects completed a structured interview, using open questions about their beliefs on binge drinking and was it a problem generally and locally. Findings: Definitions of binge drinking tended to concentrate on intoxication and some described a dependent drinking pattern. Causes and solutions offered were varied but pointed up levels of deprivation in respect of jobs and entertainment. More subjects regarded binge drinking as a problem in society than locally, which is consistent with research suggesting that misperceptions of others’ drinking increases with social distance. Differences in beliefs were found by age and level of deprivation but not gender. It was marked that no subject offered the ‘official’ definition of bingeing or even an approximation of it. Conclusions: Further research is required if future mass media campaigns and interventions are to be relevant to the population
Equality of bond percolation critical exponents for pairs of dual lattices
For a certain class of two-dimensional lattices, lattice-dual pairs are shown
to have the same bond percolation critical exponents. A computational proof is
given for the martini lattice and its dual to illustrate the method. The result
is generalized to a class of lattices that allows the equality of bond
percolation critical exponents for lattice-dual pairs to be concluded without
performing the computations. The proof uses the substitution method, which
involves stochastic ordering of probability measures on partially ordered sets.
As a consequence, there is an infinite collection of infinite sets of
two-dimensional lattices, such that all lattices in a set have the same
critical exponents.Comment: 10 pages, 7 figure
0103-72.6: A New Oxygen-Rich Supernova Remnant in the Small Magellanic Cloud
010372.6, the second brightest X-ray supernova remnant (SNR) in the Small
Magellanic Cloud (SMC), has been observed with the {\it Chandra X-Ray
Observatory}. Our {\it Chandra} observation unambiguously resolves the X-ray
emission into a nearly complete, remarkably circular shell surrounding bright
clumpy emission in the center of the remnant. The observed X-ray spectrum for
the central region is evidently dominated by emission from reverse shock-heated
metal-rich ejecta. Elemental abundances in this ejecta material are
particularly enhanced in oxygen and neon, while less prominent in the heavier
elements Si, S, and Fe. We thus propose that 010372.6 is a new
``oxygen-rich'' SNR, making it only the second member of the class in the SMC.
The outer shell is the limb-brightened, soft X-ray emission from the swept-up
SMC interstellar medium. The presence of O-rich ejecta and the SNR's location
within an H{\small II} region attest to a massive star core-collapse origin for
010372.6. The elemental abundance ratios derived from the ejecta suggest an
18 M progenitor star.Comment: 6 pages (ApJ emulator format), including 5 figures and 2 tables. For
high quality Figs.1,2, & 3, contact [email protected]. Accepted by the ApJ
Letter
Signal enhancement using time-frequency based denoising
This thesis investigates and compares time and wavelet-domain denoising techniques where received signals contain broadband noise. We consider how time and wavelet-domain denoising schemes and their combinations compare in the mean squared error sense. This work applies Wiener prediction and Median filtering as they do not require any prior signal knowledge. In the wavelet-domain we use soft or hard thresholding on the detail coefficients. In addition, we explore the effect of these wavelet-domain thresholding techniques on the coefficients associated with cycle-spinning and the newly proposed recursive cycle-spinning scheme. Finally, we note that thresholding does not make an attempt to de-noise coefficients that remain after thresholding; therefore we apply time domain techniques to the remaining detail coefficients from the first level of decomposition in an attempt to de-noise them further prior to reconstruction. This thesis applies and compares these techniques using a mean squared error criterion to identify the best performing in a robust test signal environment. We find that soft thresholding with Stein's Unbiased Risk Estimate (SURE) thresholding produces the best mean squared error results in each test case and that the addition of Wiener prediction to the first level of decomposition coefficients leads to a slightly enhanced performance. Finally, we illustrate the effects of denoising algorithms on longer data segments.http://archive.org/details/signalenhancemen109456112Lieutenant, United States NavyApproved for public release; distribution is unlimited
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Observations of X-rays and Thermal Dust Emission from the Supernova Remnant Kes 75
We present Spitzer Space Telescope and Chandra X-ray Observatory observations
of the composite Galactic supernova remnant Kes 75 (G29.7-0.3). We use the
detected flux at 24 microns and hot gas parameters from fitting spectra from
new, deep X-ray observations to constrain models of dust emission, obtaining a
dust-to-gas mass ratio M_dust/M_gas ~0.001. We find that a two-component
thermal model, nominally representing shocked swept-up interstellar or
circumstellar material and reverse-shocked ejecta, adequately fits the X-ray
spectrum, albeit with somewhat high implied densities for both components. We
surmise that this model implies a Wolf-Rayet progenitor for the remnant. We
also present infrared flux upper limits for the central pulsar wind nebula.Comment: 7 pages, 2 tables, 4 figures, uses emulateapj. Accepted for
publication in Ap
A Half-Megasecond Chandra Observation of the Oxygen-Rich Supernova Remnant G292.0+1.8
We report on our initial analysis of a deep 510 ks observation of the
Galactic oxygen-rich supernova remnant (SNR) G292.0+1.8 with the {\it Chandra
X-ray Observatory}. Our new {\it Chandra} ACIS-I observation has a larger field
of view and an order of magnitude deeper exposure than the previous {\it
Chandra} observation, which allows us to cover the entire SNR and to detect new
metal-rich ejecta features. We find a highly non-uniform distribution of
thermodynamic conditions of the X-ray emitting hot gas that correlates well
with the optical [O {\small III}] emission, suggesting the possibility that the
originating supernova explosion of G292.0+1.8 was itself asymmetric. We also
reveal spectacular substructures of a torus, a jet, and an extended central
compact nebula all associated with the embedded pulsar J11245916.Comment: 10 pages including 1 table and 2 figures (both figures are color),
accepted by ApJ Letter
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