1,987 research outputs found
Evidence for the Galactic X-ray Bulge II
A mosaic of 5 \ros~PSPC pointed observations in the Galactic plane
() reveals X-ray shadows in the keV band cast by
distant molecular clouds. The observed on-cloud and off-cloud X-ray fluxes
indicate that % and % of the diffuse X-ray background in this
direction in the \tq~keV and 1.5 keV bands, respectively, originates behind the
molecular gas which is located at 3 kpc from the Sun. The implication of
the derived background X-ray flux beyond the absorbing molecular cloud is
consistent with, and lends further support to recent observations of a Galactic
X-ray bulge.Comment: 19 pages, 5 figures, 2 table
Report on OTHER proposals for SSPEX
The only unifying factor among the experiments discussed is that they are all unique Opportunities and/or Techniques for High-caliber Experimental Research (OTHER). Thirteen of the experiments are briefly described
Stringent Constraint on Galactic Positron Production
The intense 0.511 MeV gamma-ray line emission from the Galactic Center
observed by INTEGRAL requires a large annihilation rate of nonrelativistic
positrons. If these positrons are injected at even mildly relativistic
energies, higher-energy gamma rays will also be produced. We calculate the
gamma-ray spectrum due to inflight annihilation and compare to the observed
diffuse Galactic gamma-ray data. Even in a simplified but conservative
treatment, we find that the positron injection energies must be
MeV, which strongly constrains models for Galactic positron production.Comment: 4 pages, 2 figures; minor revisions, accepted for publication in PR
Measurement crosstalk between two phase qubits coupled by a coplanar waveguide
We analyze the measurement crosstalk between two flux-biased phase qubits
coupled by a resonant coplanar waveguide cavity. After the first qubit is
measured, the superconducting phase can undergo damped oscillations resulting
in an a.c. voltage that produces a frequency chirped noise signal whose
frequency crosses that of the cavity. We show experimentally that the coplanar
waveguide cavity acts as a bandpass filter that can significantly reduce the
crosstalk signal seen by the second qubit when its frequency is far from the
cavity's resonant frequency. We present a simple classical description of the
qubit behavior that agrees well with the experimental data. These results
suggest that measurement crosstalk between superconducting phase qubits can be
reduced by use of linear or possibly nonlinear resonant cavities as coupling
elements.Comment: 4 pages, 3 figure
Sleep hygiene behaviours in Iranian adolescents: an application of the Theory of Planned Behavior
Poor sleep quality and inadequate sleep in adolescents are a rising
trend globally. The Theory of Planned Behaviour (TPB)—which centres
on an individual’s attitude toward performing the behaviour, subjective
norms and perceived behavioural control—has been applied to examine
sleep hygiene behaviours in young adults. We expanded on prior works
by using a longitudinal design to examine the effects of TPB factors,
together with sleep hygiene knowledge and planning constructs, on
sleep hygiene behaviours and on sleep quality and health in a group of
Iranian adolescents. A total of 1822 healthy adolescents (mean
age = 13.97) from 25 high schools in Qazvin, Iran, completed a selfreported
survey at baseline and 6 months later. Structural equation modelling
(SEM) was used to delineate the pathway from adolescents’ sleep
hygiene knowledge, TPB constructs of their behavioural intentions and
sleep hygiene behaviours and their sleep quality and self-reported
health. The SEM model demonstrated that although behavioural
intention, coping planning and action planning predicted the sleep
hygiene behaviours positively 6 months later with acceptable model fit
[comparative fit index (CFI) = 0.936; Tucker–Lewis index (TLI) = 0.902;
root mean square error of approximation (RMSEA) = 0.080; standardized
root mean square residual (SRMR) = 0.044], sleep hygiene
knowledge did not predict behavioural intentions significantly. Sleep
hygiene behaviours were associated with sleep quality and psychiatric
wellbeing. Thus, the TPB, combined with coping and action planning, is
useful in understanding the sleep hygiene behaviours of adolescents.
Health-care providers may want to emphasize TPB constructs and
coping and action planning to improve adolescents’ sleep hygiene
behaviours, rather than rely solely upon increasing adolescents’ sleep
hygiene knowledge
An objective framework to test the quality of candidate indicators of good environmental status
Large efforts are on-going within the EU to prepare the Marine Strategy Framework Directive's (MSFD) assessment of the environmental status of the European seas. This assessment will only be as good as the indicators chosen to monitor the 11 descriptors of good environmental status (GEnS). An objective and transparent framework to determine whether chosen indicators actually support the aims of this policy is, however, not yet in place. Such frameworks are needed to ensure that the limited resources available to this assessment optimize the likelihood of achieving GEnS within collaborating states. Here, we developed a hypothesis-based protocol to evaluate whether candidate indicators meet quality criteria explicit to the MSFD, which the assessment community aspires to. Eight quality criteria are distilled from existing initiatives, and a testing and scoring protocol for each of them is presented. We exemplify its application in three worked examples, covering indicators for three GEnS descriptors (1, 5, and 6), various habitat components (seaweeds, seagrasses, benthic macrofauna, and plankton), and assessment regions (Danish, Lithuanian, and UK waters). We argue that this framework provides a necessary, transparent and standardized structure to support the comparison of candidate indicators, and the decision-making process leading to indicator selection. Its application could help identify potential limitations in currently available candidate metrics and, in such cases, help focus the development of more adequate indicators. Use of such standardized approaches will facilitate the sharing of knowledge gained across the MSFD parties despite context-specificity across assessment regions, and support the evidence-based management of European seas
Lattice vibrations of BeO
Parts of the dispersion relations for BeO have been measured. These relations are for waves moving in the [100] direction with their polarization vectors in the (0001) plane. The initial slopes of the measured acoustical branches agree with those obtained from ultrasonics. Branch intercepts at the zone centers of 84 meV (1.27 x 1013 rad/sec) and possibly 5 meV (8 x 1012 rad/sec) were found. The dispersion relations are correlated with infrared. Reststrahlen and "frequency spectra" measurements and proposed models.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/33368/1/0000766.pd
Galactic-Centre Gamma Rays in CMSSM Dark Matter Scenarios
We study the production of gamma rays via LSP annihilations in the core of
the Galaxy as a possible experimental signature of the constrained minimal
supersymmetric extension of the Standard Model (CMSSM), in which
supersymmetry-breaking parameters are assumed to be universal at the GUT scale,
assuming also that the LSP is the lightest neutralino chi. The part of the
CMSSM parameter space that is compatible with the measured astrophysical
density of cold dark matter is known to include a stau_1 - chi coannihilation
strip, a focus-point strip where chi has an enhanced Higgsino component, and a
funnel at large tanb where the annihilation rate is enhanced by the poles of
nearby heavy MSSM Higgs bosons, A/H. We calculate the total annihilation rates,
the fractions of annihilations into different Standard Model final states and
the resulting fluxes of gamma rays for CMSSM scenarios along these strips. We
observe that typical annihilation rates are much smaller in the coannihilation
strip for tanb = 10 than along the focus-point strip or for tanb = 55, and that
the annihilation branching ratios differ greatly between the different dark
matter strips. Whereas the current Fermi-LAT data are not sensitive to any of
the CMSSM scenarios studied, and the calculated gamma-ray fluxes are probably
unobservably low along the coannihilation strip for tanb = 10, we find that
substantial portions of the focus-point strips and rapid-annihilation funnel
regions could be pressured by several more years of Fermi-LAT data, if
understanding of the astrophysical background and/or systematic uncertainties
can be improved in parallel.Comment: 33 pages, 12 figures, comments and references added, version to
appear in JCA
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