1,750 research outputs found
X-Ray Emitting Ejecta of Supernova Remnant N132D
The brightest supernova remnant in the Magellanic Clouds, N132D, belongs to
the rare class of oxygen-rich remnants, about a dozen objects that show optical
emission from pure heavy-element ejecta. They originate in explosions of
massive stars that produce large amounts of O, although only a tiny fraction of
that O is found to emit at optical wavelengths. We report the detection of
substantial amounts of O at X-ray wavelengths in a recent 100 ks Chandra ACIS
observation of N132D. A comparison between subarcsecond-resolution Chandra and
Hubble images reveals a good match between clumpy X-ray and optically emitting
ejecta on large (but not small) scales. Ejecta spectra are dominated by strong
lines of He- and H-like O; they exhibit substantial spatial variations
partially caused by patchy absorption within the LMC. Because optical ejecta
are concentrated in a 5 pc radius elliptical expanding shell, the detected
ejecta X-ray emission also originates in this shell.Comment: 5 pages, 6 figures, ApJ Letters, in pres
A compact design for a magnetic synchrotron to store beams of hydrogen atoms
We present a design for an atomic synchrotron consisting of 40 hybrid
magnetic hexapole lenses arranged in a circle. We show that for realistic
parameters, hydrogen atoms with a velocity up to 600 m/s can be stored in a
1-meter diameter ring, which implies that the atoms can be injected in the ring
directly from a pulsed supersonic beam source. This ring can be used to study
collisions between stored hydrogen atoms and molecular beams of many different
atoms and molecules. The advantage of using a synchrotron is two-fold: (i) the
collision partners move in the same direction as the stored atoms, resulting in
a small relative velocity and thus a low collision energy, and (ii) by storing
atoms for many round-trips, the sensitivity to collisions is enhanced by a
factor of 100-1000. In the proposed ring, the cross-sections for collisions
between hydrogen, the most abundant atom in the universe, with any atom or
molecule that can be put in a beam, including He, H, CO, ammonia and OH can
be measured at energies below 100 K. We discuss the possibility to use optical
transitions to load hydrogen atoms into the ring without influencing the atoms
that are already stored. In this way it will be possible to reach high
densities of stored hydrogen atoms.Comment: 9 pages, 3 figure
Operationalisation of a biopsychosocial approach for the non-pharmacological management of patients with chronic musculoskeletal pain in low- and middle-income countries: A systematic review
Background
Chronic musculoskeletal pain is a major health concern. The biopsychosocial approach is an evidence-based approach recommended for managing chronic musculoskeletal pain. However, the evidence for this approach is largely reported from high-income countries; therefore, it is important to ascertain how biopsychosocial approaches are operationalised in low- and middle-income countries to inform practice.
Aim
To examine the evidence for the operationalization of biopsychosocial interventions in managing patients with chronic musculoskeletal pain in low-and middle-income countries.
Methods
The search included studies published in English from 2008 to September 2019 in: Cochrane library, OVID, CINAHL, Scopus, PUBMED, Web of Science, and SportDiscus. Randomised and non-randomised trials using a biopsychosocial intervention were considered. The review team developed a search strategy; two independent reviewers screened and assessed results for quality.
Results
Sixteen studies were included (n = 996) with mainly low back pain populations (n = 11 studies). Others were osteoarthritis (n = 1) and other musculoskeletal pain (n = 4). The majority (n = 12) of studies attained fair to poor quality, three had good quality, one scored excellent quality. Interventions applied biopsychosocial principles such as cognitive functional therapy, and graded activity, delivered by healthcare professionals such as physiotherapists and doctors. However, most results provided insufficient information regarding healthcare professionals' capacity to deliver interventions, lack of information regarding intervention delivery and training of healthcare professionals.
Conclusions
The results highlight the potential for delivering biopsychosocial interventions in low- and middle-income countries; however, future research should consider robust methodological approaches with clear details to achieve high-quality trials
Warble infestations in some Canadian caribou and their significance
Warble fly larvae (Oedemagena tarandi) occurred in 97-100% of barren-ground caribou (R.t. groen-landicus) sampled in March from the Beverly herd. In December, they occurred in 98% of males and 75% of females. Larvae numbers increased up to several-fold from December to March. Within age classes, males generally were more heavily infected than females. Annual differences were small. Larvae occurred in 14 and 26% of two populations of Peary caribou (Rangifer tarandus pearyi) on the Canadian Arctic Islands. In them, incidences of larvae were unrelated to sex or age. Greater than average numbers of larvae in barren-ground caribou sometimes were associated with females in relatively poor condition and therefore less fecund. These results are discussed in relation to current hypotheses of the factors that affect warble infections
Dense, Fe-rich Ejecta in Supernova Remnants DEM L238 and DEM L249: A New Class of Type Ia Supernova?
We present observations of two LMC supernova remnants (SNRs), DEM L238 and
DEM L249, with the Chandra and XMM-Newton X-ray satellites. Bright central
emission, surrounded by a faint shell, is present in both remnants. The central
emission has an entirely thermal spectrum dominated by strong Fe L-shell lines,
with the deduced Fe abundance in excess of solar and not consistent with the
LMC abundance. This Fe overabundance leads to the conclusion that DEM L238 and
DEM L249 are remnants of thermonuclear (Type Ia) explosions. The shell emission
originates in gas swept up and heated by the blast wave. A standard Sedov
analysis implies about 50 solar masses in both swept-up shells, SNR ages
between 10,000 and 15,000 yr, low (< 0.05 cm^-3) preshock densities, and
subluminous explosions with energies of 3x10^50 ergs. The central Fe-rich
supernova ejecta are close to collisional ionization equilibrium. Their
presence is unexpected, because standard Type Ia SNR models predict faint
ejecta emission with short ionization ages. Both SNRs belong to a previously
unrecognized class of Type Ia SNRs characterized by bright interior emission.
Denser than expected ejecta and/or a dense circumstellar medium around the
progenitors are required to explain the presence of Fe-rich ejecta in these
SNRs. Substantial amounts of circumstellar gas are more likely to be present in
explosions of more massive Type Ia progenitors. DEM L238, DEM L249, and similar
SNRs could be remnants of ``prompt'' Type Ia explosions with young (~100 Myr
old) progenitors.Comment: 24 pages, 8 figures, ApJ, in pres
‘Black like Me’: A Critical Analysis of Arrest Practices Based on Skin Color in the Gauteng Province, South Africa
Objective: This article looks at the everyday life and realities of current practices employed by the South African Police Service (SAPS) officials, by shedding light on the experiences and practices on profiling search and effecting arrest based on race and skin color in the Gauteng Province. Particularly, this article examines the experiences of the SAPS officials to measure police perception of the skin color of foreign nationals, and to establish if wrongful arrests were linked to skin color stereotyping.
Methods: The theoretical approach employed the social identity theory (SIT) was used to interpret the results. A survey questionnaire consisting of the New Immigration Survey (NIS) Skin Color Scale with 10 shades of skin color mapped to a pictorial guide, as well as a self-report measure on wrongful arrests, was administered to 80 SAPS officials, who performed visible policing duties. The research sample consisted of two SAPS groups from two different contexts, namely township and urban contexts. The Statistical Package for the Social Sciences (SPSS) software was used to conduct Pearson’s correlation and comparative analyses.
Results: The results showed that the SAPS officials stereotyped foreign nationals as dark-skinned. The skin color stereotype was, however, not correlated to wrongful arrests. The study concluded that although respondents perceived that South Africans were distinguishable from foreign nationals based on skin color or tone, identification processes were not influenced by this stereotype belief
A systematic review of outcome measures utilised to measure the change in self-management in clinical trials in non-cancer chronic pain
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