4,508 research outputs found
Fluid lubricant system Patent
Lubrication for bearings by capillary action from oil reservoir of porous materia
Comparison of Fission Electric Cell Geometries
Comparison has been made of the relative power-to-weight ratios calculated for fission-electric cell reactor power systems based upon cells of plane, cylindrical, and spherical geometry. It is demonstrated that for systems of equal power output, the choice of cell geometry does not greatly affect the total weight of the system
RXTE Observations of LMC X-1 and LMC X-3
Of all known persistent stellar-mass black hole candidates, only LMC X-1 and
LMC X-3 consistently show spectra that are dominated by a soft, thermal
component. We present results from long (170ksec) Rossi X-ray Timing Explorer
(RXTE) observations of LMC X-1 and LMC X-3 made in 1996 December. The spectra
can be described by a multicolor disk blackbody plus an additional high-energy
power-law. Even though the spectra are very soft (Gamma is about 2.5), RXTE
detected a significant signal from LMC X-3 up to energies of 50keV, the hardest
energy at which the object was ever detected.
Focusing on LMC X-3, we present results from the first year of an ongoing
monitoring campaign with RXTE which started in 1997 January. We show that the
appearance of the object changes considerably over its ~200d long cycle. This
variability can either be explained by periodic changes in the mass transfer
rate or by a precessing accretion disk analogous to Her X-1.Comment: 4 pages, 5 figures, also available at
http://aitzu3.ait.physik.uni-tuebingen.de/publications/preprints1998.html to
be published in "Highlights of X-Ray Astronomy, a symposium in honour of
Joachim Truemper" (B. Aschenbach et al., eds.), MPE Repor
Energetics and dynamics of simple impulsive solar flares
Flare energetics and dynamics were studied using observations of simple impulsive spike bursts. A large, homogeneous set of events was selected to enable the most definite tests possible of competing flare models, in the absence of spatially resolved observations. The emission mechanisms and specific flare models that were considered in this investigation are described, and the derivations of the parameters that were tested are presented. Results of the correlation analysis between soft and hard X-ray energetics are also presented. The ion conduction front model and tests of that model with the well-observed spike bursts are described. Finally, conclusions drawn from this investigation and suggestions for future studies are discussed
Discovery of Recurring Soft to Hard State Transitions in LMC X-3
We present the analysis of an RXTE monitoring campaign of the canonical soft
state black hole candidates LMC X-1 and LMC X-3. In contrast to LMC X-1, which
does not exhibit any periodic spectral changes, we find that LMC X-3 exhibits
stron spectral variability on time scales of days to weeks. For typical RXTE
ASM count rates, the luminosity variations of LMC X-3 are due to changes of the
phenomenological disk blackbody temperature. During episodes of especially low
luminosity (ASM count rates < 0.6 counts/sec), kT strongly decreases and the
power law significantly hardens to a photon index of ~1.8. These changes are
consistent with state changes of LMC X-3 from the soft state to the canonical
hard state of galactic black hole candidates. We argue that the long term
variability of LMC X-3 might be due to a wind-driven limit cycle such as
discussed by Shields et al. (1986)Comment: MNRAS, in press, added discussion on LMC X-1 correlations, cosmetic
updates to table
Stromal cell ratio based on automated image analysis as a predictor for platinum-resistant recurrent ovarian cancer.
Background Identifying high-risk patients for platinum resistance is critical for improving clinical management of ovarian cancer. We aimed to use automated image analysis of hematoxylin & eosin (H&E) stained sections to identify the association between microenvironmental composition and platinum-resistant recurrent ovarian cancer.Methods Ninety-one patients with ovarian cancer containing the data of automated image analysis for H&E histological sections were initially reviewed.Results Seventy-one patients with recurrent disease were finally identified. Among 30 patients with high stromal cell ratio, 60% of the patients had platinum-resistant recurrence, which was significantly higher than the rate in patients with low stromal cell ratio (9.80%, P <  0.001). Multivariate logistic regression analysis revealed elevated CA125 level after 3 cycles of chemotherapy (P <  0.001) and high stromal cell ratio (P = 0.002) were the negative predictors of platinum-resistant relapse. The area under the curve (AUC) of receiver operating characteristic (ROC) curves of the models for predicting platinum-resistant recurrence with stromal cell ratio, normalization of CA125 level, and the combination of two parameters were 0.78, 0.79, and 0.89 respectively.Conclusions Our results demonstrated stromal cell ratio based on automated image analysis may be a potential predictor for ovarian cancer patients at high risk of platinum-resistant recurrence, and it could improve the predictive value of model when combined with normalization of CA125 level after 3 cycles of chemotherapy
Multifrequency Observations of the Virgo Blazars 3C 273 and 3C 279 in CGRO Cycle 8
We report first observational results of multifrequency campaigns on the
prominent Virgo blazars 3C 273 and 3C 279 which were carried out in January and
February 1999. Both blazars are detected from radio to gamma-ray energies. We
present the measured X- to gamma-ray spectra of both sources, and for 3C 279 we
compare the 1999 broad-band (radio to gamma-ray) spectrum to measured previous
ones.Comment: 5 pages including 3 figures, latex2e, to appear in: 'Proc. of the 5th
Compton Symposium', AIP, in pres
Orbital and Super-Orbital Periods of 1E 1740.7-2942 and GRS 1758-258
Five years of Rossi X-ray Timing Explorer (RXTE) observations of the Galactic
black-hole candidates 1E 1740.7-2942 and GRS 1758-258 show a periodic
modulation with amplitude 3-4% in each source at 12.73 +/- 0.05 dy and 18.45
+/- 0.10 dy, respectively. We interpret the modulations as orbital, suggesting
that the objects have red-giant companions. Combining the RXTE data with
earlier data (Zhang, Harmon & Liang 1997) from the Burst and Transient Source
Experiment on the Compton Gamma-Ray Observatory, we find a long period or
quasi-period of about 600 dy in 1E 1740.7-2942, and a suggestion of a similar
600-dy period in GRS 1758-258. These timescales are longer than any yet found
for either precessing systems like Her X-1 and SS 433 or binaries like LMC X-3
and Cyg X-1 with more irregular long periods.Comment: 13 pages, 5 figures, accepted by The Astrophysical Journal Letter
- …