230 research outputs found
Dynamic hip screw fixation: Is the tip-apex distance the most important predictor for lag screw cutout?
Psychological wellness and health-related stigma: A pilot study of an acceptance-focused cognitive behavioural intervention for people with lung cancer
People with lung cancer experience health-related stigma that is related to poorer psychosocial and quality of life outcomes. The present Phase 1 study applied mixed methods to test the acceptability of an acceptance-focused cognitive behavioural intervention targeting stigma for this patient group. Fourteen lung cancer patients completed a 6-week Psychological Wellness intervention with pre- and post-test outcome measures of psychological and cancer-specific distress, depression, health-related stigma and quality of life. In-depth interviews applying interpretative phenomenological analysis assessed participants\u27 experiences of the intervention. Moderate to large improvements were observed in psychological (ηp 2=0.182) and cancer-specific distress (ηp 2=0.056); depression (ηp 2=0.621); health-related stigma (ηp 2=0.139). In contrast, quality of life declined (ηp 2=0.023). The therapeutic relationship; self-management of distress; and relationship support were highly valued aspects of the intervention. Barriers to intervention included avoidance and practical issues. The lung cancer patients who completed the Psychological Wellness intervention reported improvements in psychological outcomes and decreases in stigma in the face of declining quality of life with patients reporting personal benefit from their own perspectives. A randomised controlled trial is warranted to establish the effectiveness of this approach
Social Network Analysis
The proposed roundtable will bring together researchers from the iSchool community to discuss trends, new questions, and innovative ideas regarding social networks. For instance, how to discover and analyze subcommunities within a very large social network? How new behaviors in on-line social networks emerge through interactions? How social networks hidden within blogs, fora, and other forms of on-line communications can be identified? What are the impacts of social networks on social activities? How do social networks form, evolve, and grow? How ideas are spread over time and space using social networks? The proposed roundtable will stress the interdisciplinary challenges of these and other topics related to social networks.
Through these interactions, we hope the roundtable can help the iSchool community in establishing one or multiple grand challenges regarding social networks and launching an effort to develop a strategy that aims to position iSchools to be leaders in addressing these grand challenges
Detection of a Thermal Spectral Component in the Prompt Emission of GRB 100724B
Observations of GRB 100724B with the Fermi Gamma-Ray Burst Monitor (GBM) find
that the spectrum is dominated by the typical Band functional form, which is
usually taken to represent a non-thermal emission component, but also includes
a statistically highly significant thermal spectral contribution. The
simultaneous observation of the thermal and non-thermal components allows us to
confidently identify the two emission components. The fact that these seem to
vary independently favors the idea that the thermal component is of
photospheric origin while the dominant non-thermal emission occurs at larger
radii. Our results imply either a very high efficiency for the non-thermal
process, or a very small size of the region at the base of the flow, both quite
challenging for the standard fireball model. These problems are resolved if the
jet is initially highly magnetized and has a substantial Poynting flux.Comment: 6 pages, 3 figures, 1 table, Accepted for publication in the
Astrophysical Journal Letters November, 23 2010 (Submitted October, 20 2010
Rest-frame properties of 32 gamma-ray bursts observed by the Fermi Gamma-Ray Burst Monitor
Aims: In this paper we study the main spectral and temporal properties of
gamma-ray bursts (GRBs) observed by Fermi/GBM. We investigate these key
properties of GRBs in the rest-frame of the progenitor and test for possible
intra-parameter correlations to better understand the intrinsic nature of these
events. Methods: Our sample comprises 32 GRBs with measured redshift that were
observed by GBM until August 2010. 28 of them belong to the long-duration
population and 4 events were classified as short/hard bursts. For all of these
events we derive, where possible, the intrinsic peak energy in the spectrum (\eprest), the duration in the rest-frame, defined as the
time in which 90% of the burst fluence was observed (\tninetyrest) and the
isotropic equivalent bolometric energy (\eiso). Results: The distribution of
\eprest has mean and median values of 1.1 MeV and 750 keV, respectively. A
log-normal fit to the sample of long bursts peaks at ~800 keV. No high-\ep
population is found but the distribution is biased against low \ep values. We
find the lowest possible \ep that GBM can recover to be ~ 15 keV. The
\tninetyrest distribution of long GRBs peaks at ~10 s. The distribution of
\eiso has mean and median values of erg and erg, respectively. We confirm the tight correlation between \eprest
and \eiso (Amati relation) and the one between \eprest and the 1-s peak
luminosity () (Yonetoku relation). Additionally, we observe a parameter
reconstruction effect, i.e. the low-energy power law index gets softer
when \ep is located at the lower end of the detector energy range. Moreover, we
do not find any significant cosmic evolution of neither \eprest nor
\tninetyrest.Comment: accepted by A&
Temporal Deconvolution study of Long and Short Gamma-Ray Burst Light curves
The light curves of Gamma-Ray Bursts (GRBs) are believed to result from
internal shocks reflecting the activity of the GRB central engine. Their
temporal deconvolution can reveal potential differences in the properties of
the central engines in the two populations of GRBs which are believed to
originate from the deaths of massive stars (long) and from mergers of compact
objects (short). We present here the results of the temporal analysis of 42
GRBs detected with the Gamma-ray Burst Monitor onboard the Fermi Gamma-ray
Space Telescope. We deconvolved the profiles into pulses, which we fit with
lognormal functions. The distributions of the pulse shape parameters and
intervals between neighboring pulses are distinct for both burst types and also
fit with lognormal functions. We have studied the evolution of these parameters
in different energy bands and found that they differ between long and short
bursts. We discuss the implications of the differences in the temporal
properties of long and short bursts within the framework of the internal shock
model for GRB prompt emission.Comment: 38 pages, 11 figure
The Fermi GBM Gamma-Ray Burst Spectral Catalog: Four Years Of Data
In this catalog we present the updated set of spectral analyses of GRBs
detected by the Fermi Gamma-Ray Burst Monitor (GBM) during its first four years
of operation. It contains two types of spectra, time-integrated spectral fits
and spectral fits at the brightest time bin, from 943 triggered GRBs. Four
different spectral models were fitted to the data, resulting in a compendium of
more than 7500 spectra. The analysis was performed similarly, but not
identically to Goldstein et al. 2012. All 487 GRBs from the first two years
have been re-fitted using the same methodology as that of the 456 GRBs in years
three and four. We describe, in detail, our procedure and criteria for the
analysis, and present the results in the form of parameter distributions both
for the observer-frame and rest-frame quantities. The data files containing the
complete results are available from the High-Energy Astrophysics Science
Archive Research Center (HEASARC).Comment: Accepted for publication in ApJ
Time-Resolved Spectroscopy of the 3 Brightest and Hardest Short Gamma-Ray Bursts Observed with the FGST Gamma-Ray Burst Monitor
From July 2008 to October 2009, the Gamma-ray Burst Monitor (GBM) on board
the Fermi Gamma-ray Space Telescope (FGST) has detected 320 Gamma-Ray Bursts
(GRBs). About 20% of these events are classified as short based on their T90
duration below 2 s. We present here for the first time time-resolved
spectroscopy at timescales as short as 2 ms for the three brightest short GRBs
observed with GBM. The time-integrated spectra of the events deviate from the
Band function, indicating the existence of an additional spectral component,
which can be fit by a power-law with index ~-1.5. The time-integrated Epeak
values exceed 2 MeV for two of the bursts, and are well above the values
observed in the brightest long GRBs. Their Epeak values and their low-energy
power-law indices ({\alpha}) confirm that short GRBs are harder than long ones.
We find that short GRBs are very similar to long ones, but with light curves
contracted in time and with harder spectra stretched towards higher energies.
In our time-resolved spectroscopy analysis, we find that the Epeak values range
from a few tens of keV up to more than 6 MeV. In general, the hardness
evolutions during the bursts follows their flux/intensity variations, similar
to long bursts. However, we do not always see the Epeak leading the light-curve
rises, and we confirm the zero/short average light-curve spectral lag below 1
MeV, already established for short GRBs. We also find that the time-resolved
low-energy power-law indices of the Band function mostly violate the limits
imposed by the synchrotron models for both slow and fast electron cooling and
may require additional emission processes to explain the data. Finally, we
interpreted these observations in the context of the current existing models
and emission mechanisms for the prompt emission of GRBs.Comment: 14 pages, 10 figures, 9 tables, Accepted for publication in the
Astrophysical Journal September, 23 2010 (Submitted May, 16 2010)
Corrections: 1 reference updated, figure 10 captio
First-year Results of Broadband Spectroscopy of the Brightest Fermi-GBM Gamma-Ray Bursts
We present here our results of the temporal and spectral analysis of a sample
of 52 bright and hard gamma-ray bursts (GRBs) observed with the Fermi Gamma-ray
Burst Monitor (GBM) during its first year of operation (July 2008-July 2009).
Our sample was selected from a total of 253 GBM GRBs based on each event peak
count rate measured between 0.2 and 40MeV. The final sample comprised 34 long
and 18 short GRBs. These numbers show that the GBM sample contains a much
larger fraction of short GRBs, than the CGRO/BATSE data set, which we explain
as the result of our (different) selection criteria and the improved GBM
trigger algorithms, which favor collection of short, bright GRBs over BATSE. A
first by-product of our selection methodology is the determination of a
detection threshold from the GBM data alone, above which GRBs most likely will
be detected in the MeV/GeV range with the Large Area Telescope (LAT) onboard
Fermi. This predictor will be very useful for future multiwavelength GRB follow
ups with ground and space based observatories. Further we have estimated the
burst durations up to 10MeV and for the first time expanded the duration-energy
relationship in the GRB light curves to high energies. We confirm that GRB
durations decline with energy as a power law with index approximately -0.4, as
was found earlier with the BATSE data and we also notice evidence of a possible
cutoff or break at higher energies. Finally, we performed time-integrated
spectral analysis of all 52 bursts and compared their spectral parameters with
those obtained with the larger data sample of the BATSE data. We find that the
two parameter data sets are similar and confirm that short GRBs are in general
harder than longer ones.Comment: 40 pages, 11 figures, 3 tables, Submitted to Ap
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