2,194 research outputs found
Gamma rays from ultracompact primordial dark matter minihalos
Ultracompact minihalos have recently been proposed as a new class of dark
matter structure. These minihalos would be produced by phase transitions in the
early Universe or features in the inflaton potential, and constitute
non-baryonic massive compact halo objects (MACHOs) today. We examine the
prospect of detecting ultracompact minihalos in gamma-rays if dark matter
consists of self-annihilating particles. We compute present-day fluxes from
minihalos produced in the electron-positron annihilation epoch, and the QCD and
electroweak phase transitions in the early Universe. Even at a distance of 100
pc, minihalos produced during the electron-positron annihilation epoch should
be eminently detectable today, either by the Fermi satellite, current Air
Cherenkov telescopes, or even in archival EGRET data. Within ~1 pc, minihalos
formed in the QCD phase transition would have similar predicted fluxes to the
dwarf spheroidal galaxies targeted by current indirect dark matter searches, so
might also be detectable by present or upcoming experiments.Comment: 5 pages, 3 figures. Minor update to match published version of
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Where to draw the line? The influence of prior relationship, perpetrator-target sex and perpetrator motivation on the point at which behavior ‘crosses the line’ and becomes stalking
The present study examines the influence of prior relationship (intimate, non-intimate), perpetrator-target sex (male-female, female-male) and perpetrator motivation (romance, upset) on (1) the point at which behavior crosses the line and becomes stalking, and (2) the likelihood of offering five forms of advice to the target (formal support, informal support, protective measures, avoidance measures, threatening action). The study used a 2 × 2 × 2 between-participants experimental design. Four-hundred and sixty-one UK students read one of eight versions of a hypothetical scenario that they were informed may or may not depict a stalking situation. Analyses revealed that 97.8% (n = 451) of participants believed the perpetrator's behavior constituted stalking, and that behavior was perceived to cross the line earlier in the scenario when the perpetrator's motivation was to upset the target in the context of a non-intimate prior relationship only. Prior relationship, perpetrator-target sex and perpetrator motivation also influenced the likelihood of offering various forms of advice to the target. These findings further demonstrate the impact of situational characteristics on perceptions of stalking and highlight the importance of educational campaigns and programs to increase people's understanding of stalking
This isn\u27t the glue factory: Tesco\u27s horse meat scandal - An application of Benoit\u27s (1997) Image Repair Theory
Erratum: Observational constraints on supermassive dark stars
No abstract is available for this article
Extracting waves and vortices from Lagrangian trajectories
A method for extracting time-varying oscillatory motions from time series
records is applied to Lagrangian trajectories from a numerical model of eddies
generated by an unstable equivalent barotropic jet on a beta plane. An
oscillation in a Lagrangian trajectory is represented mathematically as the
signal traced out as a particle orbits a time-varying ellipse, a model which
captures wavelike motions as well as the displacement signal of a particle
trapped in an evolving vortex. Such oscillatory features can be separated from
the turbulent background flow through an analysis founded upon a complex-valued
wavelet transform of the trajectory. Application of the method to a set of one
hundred modeled trajectories shows that the oscillatory motions of Lagrangian
particles orbiting vortex cores appear to be extracted very well by the method,
which depends upon only a handful of free parameters and which requires no
operator intervention. Furthermore, vortex motions are clearly distinguished
from wavelike meandering of the jet---the former are high frequency, nearly
circular signals, while the latter are linear in polarization and at much lower
frequencies. This suggests that the proposed method can be useful for
identifying and studying vortex and wave properties in large Lagrangian
datasets. In particular, the eccentricity of the oscillatory displacement
signals, a quantity which is not normally considered in Lagrangian studies,
emerges as an informative diagnostic for characterizing qualitatively different
types of motion
Users’ Game Design Element Preferences in Health Behavior Change Support Systems for Physical Activity: A Best-Worst-Scaling Approach
Over the last decades, physical inactivity has become one of the leading health risk factors in modern societies. To incentivize people to be more physically active, gamified health behavior change support systems (HBCSSs) are a promising approach. These systems often make use of gamification to keep their users engaged over a sustained period of time. However, despite its popularity, gamification often fails due to insufficient designs, which neglect users’ needs. Building on extant research that investigated users’ preferences in other gamification contexts, we conduct a survey among 447 potential users of HBCSSs for physical activity, using a best-worst-scaling approach. Our results indicate that users generally prefer the game design elements progress, goals, points, and levels, which is partially different from past research on preferred game design elements in other contexts. Thus, our research contributes to the understanding of contextual differences in users’ gamification preferences
Finding high-redshift dark stars with the James Webb Space Telescope
The first stars in the history of the Universe are likely to form in the
dense central regions of 10^5-10^6 Msolar cold dark matter halos at z=10-50.
The annihilation of dark matter particles in these environments may lead to the
formation of so-called dark stars, which are predicted to be cooler, larger,
more massive and potentially more long-lived than conventional population III
stars. Here, we investigate the prospects of detecting high-redshift dark stars
with the upcoming James Webb Space Telescope (JWST). We find that dark stars at
z>6 are intrinsically too faint to be detected by JWST. However, by exploiting
foreground galaxy clusters as gravitational telescopes, certain varieties of
cool (Teff < 30000 K) dark stars should be within reach at redshifts up to
z=10. If the lifetimes of dark stars are sufficiently long, many such objects
may also congregate inside the first galaxies. We demonstrate that this could
give rise to peculiar features in the integrated spectra of galaxies at high
redshifts, provided that dark stars make up at least 1 percent of the total
stellar mass in such objects.Comment: 12 pages, 7 figures; v2: matches published versio
A GPU implementation of the Correlation Technique for Real-time Fourier Domain Pulsar Acceleration Searches
The study of binary pulsars enables tests of general relativity. Orbital
motion in binary systems causes the apparent pulsar spin frequency to drift,
reducing the sensitivity of periodicity searches. Acceleration searches are
methods that account for the effect of orbital acceleration. Existing methods
are currently computationally expensive, and the vast amount of data that will
be produced by next generation instruments such as the Square Kilometre Array
(SKA) necessitates real-time acceleration searches, which in turn requires the
use of High Performance Computing (HPC) platforms. We present our
implementation of the Correlation Technique for the Fourier Domain Acceleration
Search (FDAS) algorithm on Graphics Processor Units (GPUs). The correlation
technique is applied as a convolution with multiple Finite Impulse Response
filters in the Fourier domain. Two approaches are compared: the first uses the
NVIDIA cuFFT library for applying Fast Fourier Transforms (FFTs) on the GPU,
and the second contains a custom FFT implementation in GPU shared memory. We
find that the FFT shared memory implementation performs between 1.5 and 3.2
times faster than our cuFFT-based application for smaller but sufficient filter
sizes. It is also 4 to 6 times faster than the existing GPU and OpenMP
implementations of FDAS. This work is part of the AstroAccelerate project, a
many-core accelerated time-domain signal processing library for radio
astronomy.Comment: 20 pages, 9 figures. Accepted for publication in ApJ
Population genetic analysis of Bartonella bacilliformis isolates from areas of Peru where Carrion\u27s disease is endemic and epidemic
Carrion's disease is caused by infection with the α-proteobacterium Bartonella bacilliformis. Distribution of the disease is considered coincident with the distribution of its known vector, the sand fly Lutzomyia verrucarum. Recent epidemics of B. bacilliformis infections associated with atypical symptomatology in nonendemic regions have raised questions regarding the historic and present distribution of this bacterium and the scope of disease that infection causes. Phylogenetic relationships and genomic diversity of 18 B. bacilliformis isolates (10 isolates from a region where Carrion's disease is epidemic, Cuzco, Peru, and 8 isolates from a region where Carrion's disease is endemic, Caraz, Peru) were assessed using genomic data generated by infrequent restriction site PCR and gene sequence analysis of the flagellin gltA and ialB genes. A population genetic analysis of the genomic diversity suggests that what was once considered an epidemic region of Peru did not result from the recent introduction of B. bacilliformis
The impact of nocturnal hemodialysis on sexual function
BACKGROUND: Sexual dysfunction is common in patients with end stage renal disease (ESRD) and treatment options are limited. Observational studies suggest that nocturnal hemodialysis may improve sexual function. We compared sexual activity and responses to sexual related questions in the Kidney Disease Quality of Life Short Form questionnaire among patients randomized to frequent nocturnal or thrice weekly conventional hemodialysis. METHODS: We performed a secondary analysis of data from an RCT which enrolled 51 patients comparing frequent nocturnal and conventional thrice weekly hemodialysis. Sexual activity and responses to sexual related questions were assessed at baseline and six months using relevant questions from the Kidney Disease Quality of Life Short Form questionnaire. RESULTS: Overall, there was no difference in sexual activity, or the extent to which people were bothered by the impact of kidney disease on their sex life between the two groups between randomization and 6 months. However, women and patients age < 60 who were randomized to frequent nocturnal hemodialysis were less bothered by the impact of kidney disease on their sex life at 6 months, compared with patients allocated to conventional hemodialysis (p = 0.005 and p = 0.024 respectively). CONCLUSIONS: Our results suggest that frequent nocturnal hemodialysis is not associated with an improvement in sexual activity in all patients but might have an effect on the burden of kidney disease on sex life in women and patients less than 60 years of age. The validity of these subgroup findings require confirmation in future RCTs
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