198 research outputs found
The Spectrum and Dips of RE 0751+14: A joint evaluation of ROSAT and ASCA Archival Data
Using archival ASCA and ROSAT observations of RE 0751+14, X-ray energy
spectra, pulse profiles and the results of pulse timing analysis are presented.
The energy spectra are well-fitted by a blackbody model at low energy and a
Raymond-Smith model at high energy, together with a partial covering absorber.
A fluorescence emission line at 6.4 keV with an equivalent width eV
was resolved for the first time.Comment: To appear on Astrophysics and Space Science, vol 259, pages 191-203,
January 199
Short Gamma-Ray Bursts with Extended Emission Observed with Swift/BAT and Fermi/GBM
Some short GRBs are followed by longer extended emission, lasting anywhere
from ~10 to ~100 s. These short GRBs with extended emission (EE) can possess
observational characteristics of both short and long GRBs (as represented by
GRB 060614), and the traditional classification based on the observed duration
places some of them in the long GRB class. While GRBs with EE pose a challenge
to the compact binary merger scenario, they may therefore provide an important
link between short and long duration events. To identify the population of GRBs
with EE regardless of their initial classifications, we performed a systematic
search of short GRBs with EE using all available data (up to February 2013) of
both Swift/BAT and Fermi/GBM. The search identified 16 BAT and 14 GBM detected
GRBs with EE, several of which are common events observed with both detectors.
We investigated their spectral and temporal properties for both the spikes and
the EE, and examined correlations among these parameters. Here we present the
results of the systematic search as well as the properties of the identified
events. Finally, their properties are also compared with short GRBs with EE
observed with BATSE, identified through our previous search effort. We found
several strong correlations among parameters, especially when all of the
samples were combined. Based on our results, a possible progenitor scenario of
two-component jet is discussed.Comment: Published in MNRAS; matched to the published versio
Personal Lives? The Effects of nonwork behaviors on organizational image
Cataloged from PDF version of article.Organizational leaders may respond to employee nonwork behaviors because of the possible
influence on organizational image. We describe a typology of nonwork behaviors and discuss their
potential implications for organizational image. We explore conditions under which organizational
leaders may attempt to control employee nonwork behaviors and review the available alternatives
for organizational control. We conclude by discussing the theoretical and practical implications of
research on nonwork behavior
X-ray Spectral Variations of U Gem from Quiescence to Outburst
In this paper we report the discovery of a high energy component of the X-ray
spectra of U Gem, which can be observed while the source is in outburst. We
used Chandra and XMM-Newton observations to compare the quiescence and outburst
X-ray spectra of the source. The additional component may be the result of the
reflection of X-rays emitted from an optically thin plasma close to the white
dwarf, from the optically thick boundary layer during the outburst. Another
possible explanation is that some magnetically channeled accretion may occur
onto the equatorial belt of the primary causing shocks similar to the ones in
the intermediate polars as it was suggested by \citep{w2002}. We have also
found a timing structure at about 73 mHz (13.7 s.) in the RXTE
observation, resembling dwarf novae oscillations (DNOs).Comment: accepted by MNRAS, figure 1 replaced with a newer on
Patients With Kidney Cancer
To develop a preoperative prognostic model in order to predict recurrence-free survival in patients with nonmetastatic kidney cancer.A multi-institutional data base of 1889 patients who underwent surgical resection between 1987 and 2007 for kidney cancer was retrospectively analyzed. Preoperative variables were defined as age, gender, presentation, size, presence of radiological lymph nodes and clinical stage. Univariate and multivariate analyses of the variables were performed using the Cox proportional hazards regression model. A model was developed with preoperative variables as predictors of recurrence after nephrectomy. Internal validation was performed by Harrells concordance index.The median follow-up was 23.6 months (1222 months). During the follow-up, 258 patients (13.7) developed cancer recurrence. The median follow-up for patients who did not develop recurrence was 25 months. The median time from surgery to recurrence was 13 months. The 5-year freedom from recurrence probability was 78.6. All variables except age were associated with freedom from recurrence in multivariate analyses (P 0.05). Age was marginally significant in the univariate analysis. All variables were included in the predictive model. The calculated c-index was 0.747.This preoperative model utilizes easy to obtain clinical variables and predicts the likelihood of development of recurrent disease in patients with kidney tumors
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