8,170 research outputs found
Inflated responsibility and perfectionism in child and adolescent anorexia
Objective: The aim of the pilot study was to investigate the cognitive biases of inflated responsibility (IR) and perfectionism in children and adolescents with a diagnosis of Anorexia Nervosa
(AN). An additional aim was to provide a preliminary investigation into whether there is an interaction effect with AN severity,
measured by body mass index (BMI). Method: A cross-sectional multi-site pilot study using standardised questionnaires was
conducted and 30 young people diagnosed with AN participated.
Results: Children and adolescents with AN reported significantly higher levels of IR and perfectionism, compared to published normative non-clinical data. Self-orientated perfectionism (SOP) was associated with frequency of IR thoughts. There was also a
significant interaction effect: young people who had a higher frequency of IR thoughts and SOP had lower BMIs.
Discussion: Further independent replication of these results is needed. IR and perfectionism should be considered in the assessment and treatment of child and adolescent AN, both in individual and systemic interventions. This research also adds to the growing body of literature examining cognitive biases of obsessive– compulsive disorder in an AN population, which may offer some
insight into the overlap between the two disorders
CANOZE measurements of the Arctic ozone hole
In CANOZE 1 (Canadian Ozone Experiment), a series of 20 ozone profile measurements were made in April, 1986 from Alert at 82.5 N. CANOZE is the Canadian program for study of the Arctic winter ozone layer. In CANOZE 2, ozone profile measurements were made at Saskatoon, Edmonton, Churchill and Resolute during February and March, 1987 with ECC ozonesondes. Ground based measurements of column ozone, nitrogen dioxide and hydrochloric acid were conducted at Saskatoon. Two STRATOPROBE balloon flights were conducted on February 26 and March 19, 1987. Two aerosol flights were conducted by the University of Wyoming. The overall results of this study will be reported and compared with the NOZE findings. The results from CANOZE 3 in 1988, are also discussed. In 1988, as part of CANOZE 3, STRATOPROBE balloon flights were conducted from Saskatchewan on January 27 and February 13. A new lightweight infrared instrument was developed and test flown. A science flight was successfully conducted from Alert (82.5 N) on March 9, 1988 when the vortex was close to Alert; a good measurement of the profile of nitric acid was obtained. Overall, the Arctic spring ozone layer exhibits many of the features of the Antarctic ozone phenomenon, although there is obviously not a hole present every year. The Arctic ozone field in March, 1986 demonstrated many similarities to the Antarctic ozone hole. The TOMS imagery showed a crater structure in the ozone field similar to the Antarctic crater in October. Depleted layers of ozone were found in the profiles around 15 km, very similar to those reported from McMurdo. Enhanced levels of nitric acid were measured in air which had earlier been in the vortex. The TOMS imagery for March 1987 did not show an ozone crater, but will be examined for an ozone crater in February and March, 1988, the target date for the CANOZE 3 project
WIMP astronomy and particle physics with liquid-noble and cryogenic direct-detection experiments
Once weakly-interacting massive particles (WIMPs) are unambiguously detected
in direct-detection experiments, the challenge will be to determine what one
may infer from the data. Here, I examine the prospects for reconstructing the
local speed distribution of WIMPs in addition to WIMP particle-physics
properties (mass, cross sections) from next-generation cryogenic and
liquid-noble direct-detection experiments. I find that the common method of
fixing the form of the velocity distribution when estimating constraints on
WIMP mass and cross sections means losing out on the information on the speed
distribution contained in the data and may lead to biases in the inferred
values of the particle-physics parameters. I show that using a more general,
empirical form of the speed distribution can lead to good constraints on the
speed distribution. Moreover, one can use Bayesian model-selection criteria to
determine if a theoretically-inspired functional form for the speed
distribution (such as a Maxwell-Boltzmann distribution) fits better than an
empirical model. The shape of the degeneracy between WIMP mass and cross
sections and their offset from the true values of those parameters depends on
the hypothesis for the speed distribution, which has significant implications
for consistency checks between direct-detection and collider data. In addition,
I find that the uncertainties on theoretical parameters depends sensitively on
the upper end of the energy range used for WIMP searches. Better constraints on
the WIMP particle-physics parameters and speed distribution are obtained if the
WIMP search is extended to higher energy (~ 1 MeV).Comment: 25 pages, 27 figures, matches published versio
The energy budget in Rayleigh-Benard convection
It is shown using three series of Rayleigh number simulations of varying
aspect ratio AR and Prandtl number Pr that the normalized dissipation at the
wall, while significantly greater than 1, approaches a constant dependent upon
AR and Pr. It is also found that the peak velocity, not the mean square
velocity, obeys the experimental scaling of Ra^{0.5}. The scaling of the mean
square velocity is closer to Ra^{0.46}, which is shown to be consistent with
experimental measurements and the numerical results for the scaling of Nu and
the temperature if there are strong correlations between the velocity and
temperature.Comment: 5 pages, 3 figures, new version 13 Mar, 200
G328.4+0.2 : A large and luminous Crab-like supernova remnant
We report on radio continuum and HI observations of the radio source
G328.4+0.2 using the Australia Telescope Compact Array. Our results confirm
G328.4+0.2 to be a filled-center nebula with no surrounding shell, showing
significant linear polarization and an almost flat spectral index. These
results lead us to conclude that G328.4+0.2 is a Crab-like, or ``plerionic'',
supernova remnant (SNR), presumably powered by an unseen central pulsar. HI
absorption towards G328.4+0.2 puts a lower limit on its distance of 17.4 +/-
0.9 kpc, making it the largest (D=25 pc) and most luminous (L_R = 3e35 erg/s)
Crab-like SNR in the Galaxy. We infer G328.4+0.2 to be significantly older than
the Crab Nebula, but powered by a pulsar which is fast spinning (P<20 ms) and
which has a comparatively low magnetic field (B<1e12 G). We propose G328.4+0.2,
G74.9+1.2 and N157B as a distinct group of large-diameter, high-luminosity
Crab-like SNRs, all powered by fast-spinning low-field pulsars.Comment: 7 pages, 3 embedded EPS figures, uses emulateapj.sty. Accepted to
ApJ. Abstract corrected so that distance is now in kpc, not pc
Brewer spectrophotometer measurements in the Canadian Arctic
In the winters of 1987 and 1988 measurements were conducted with the Brewer Spectrophotometer at Alert (82.5 N) and Resolute (74.5 N). The measurements were conducted as part of our Canadian Program to search for an Arctic Ozone Hole (CANOZE). Ozone measurements were conducted in the months of December, January and February using the moon as a light source. The total ozone measurements will be compared with ozonesonde profiles, from ECC sondes, flown once per week from Alert and Resolute. A modified Brewer Spectrophotometer was used in a special study to search for chlorine dioxide at Alert in March 1987. Ground based observations at Saskatoon in February and at Alert in March 1987 failed to detect any measureable chlorine dioxide. Interference from another absorbing gas, which we speculate may be nitrous acid, prevented the measurements at the low levels of chlorine dioxide detected in the Southern Hemisphere by Solomon et al
Two Large HI Shells in the Outer Galaxy near l=279 degrees
As part of a survey of HI 21-cm emission in the Southern Milky Way, we have
detected two large shells in the interstellar neutral hydrogen near l=279 deg.
The center velocities are +36 and +59 km/s, which puts the shells at kinematic
distances of 7 and 10 kpc. The larger shell is about 610 pc in diameter and
very empty, with density contrast of at least 15 between the middle and the
shell walls. It has expansion velocity of about 20 km/s and swept up mass of
several million solar masses. The energy indicated by the expansion may be as
high as 2.4 X 10^53 ergs. We estimate its age to be 15 to 20 million years. The
smaller shell has diameter of about 400 pc, expansion velocity about 10 km/s
and swept up mass of about 10^6 solar masses.
Morphologically both regions appear to be shells, with high density regions
mostly surrounding the voids, although the first appears to have channels of
low density which connect with the halo above and below the HI layer. They lie
on the edge of the Carina arm, which suggests that they may be expanding
horizontally into the interarm region as well as vertically out of the disk. If
this interpretation is correct, this is the first detection of an HI chimney
which has blown out of both sides of the disk.Comment: 21 pages, 14 jpeg figures, accepted for publication in A
Metastable dark matter mechanisms for INTEGRAL 511 keV rays and DAMA/CoGeNT events
We explore dark matter mechanisms that can simultaneously explain the
galactic 511 keV gamma rays observed by INTEGRAL/SPI, the DAMA/LIBRA annual
modulation, and the excess of low-recoil dark matter candidates observed by
CoGeNT. It requires three nearly degenerate states of dark matter in the 4-7
GeV mass range, with splittings respectively of order an MeV and a few keV. The
top two states have the small mass gap and transitions between them, either
exothermic or endothermic, can account for direct detections. Decays from one
of the top states to the ground state produce low-energy positrons in the
galaxy whose associated 511 keV gamma rays are seen by INTEGRAL. This decay can
happen spontaneously, if the excited state is metastable (longer-lived than the
age of the universe), or it can be triggered by inelastic scattering of the
metastable states into the shorter-lived ones. We focus on a simple model where
the DM is a triplet of an SU(2) hidden sector gauge symmetry, broken at the
scale of a few GeV, giving masses of order \lsim 1 GeV to the dark gauge
bosons, which mix kinetically with the standard model hypercharge. The purely
decaying scenario can give the observed angular dependence of the 511 keV
signal with no positron diffusion, while the inelastic scattering mechanism
requires transport of the positrons over distances \sim 1 kpc before
annihilating. We note that an x-ray line of several keV in energy, due to
single-photon decays involving the top DM states, could provide an additional
component to the diffuse x-ray background. The model is testable by proposed
low-energy fixed target experiments.Comment: 27 pp, 19 figures; v2. minor clarification, added refs; v3. corrected
observed rate of positron production, added new section responding to
criticisms of arXiv:0904.1025; v4. corrected typos in eqs. (6) and (40
The 69 ms Radio Pulsar Near the Supernova Remnant RCW 103
We report the detection of the radio pulsar counterpart to the 69 ms X-ray
pulsar discovered near the supernova remnant RCW 103 (G332.4-0.4). Our
detection confirms that the pulsations arise from a rotation-powered neutron
star, which we name PSR J1617-5055. The observed barycentric period derivative
confirms that the pulsar has a characteristic age of only 8 kyr, the sixth
smallest of all known pulsars. The unusual apparent youth of the pulsar and its
proximity to a young remnant requires that an association be considered.
Although the respective ages and distances are consistent within substantial
uncertainties, the large inferred pulsar transverse velocity is difficult to
explain given the observed pulsar velocity distribution, the absence of
evidence for a pulsar wind nebula, and the symmetry of the remnant. Rather, we
argue that the objects are likely superposed on the sky; this is reasonable
given the complex area. Without an association, the question of where is the
supernova remnant left behind following the birth of PSR J1617-5055 remains
open. We also discuss a possible association between PSR J1617-5055 and the
gamma-ray source 2CG 333+01. Though an association is energetically plausible,
it is unlikely given that EGRET did not detect 2CG 333+01.Comment: 18 pages, 2 encapsulated Postscript figures, uses AAS LaTeX style
files. Accepted for publication in The Astrophysical Journal Letter
Immunocytochemical demonstration of p21 ras family oncogene product in normal mucosa and in premalignant and malignant tumours of the colorectum.
Study of the distribution of the p21 ras oncogene product as demonstrated by monoclonal antibody Y13-259 shows this protein to be apparently present in all epithelial populations of both premalignant and malignant tumours and throughout the normal foetal and adult epithelial crypt population in the colorectum. Metastatic tumour in liver shows a similar staining pattern which is less intense however than in the surrounding normal hepatocytes. Our results suggest that the presence of this protein is a widespread feature of normal cellular metabolism in certain cell types and is not restricted to those actively involved in cellular proliferation. It appears, furthermore, that neither cells at different stages of carcinogenesis nor those representing variants of a malignant phenotype can be identified using this particular antibody
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