358 research outputs found
Low State of the X-ray Burster SLX 1732-304 in the Globular Cluster Terzan 1 According to RXTE Data
Observations of the X-ray burster SLX 1732-304 in the globular cluster Terzan
1 with the PCA/RXTE instrument in April 1997 are presented. The source was in a
low state; its flux in the standard X-ray band was half the flux recorded by
the ART-P/Granat telescope also during its low state. At the same time, its
spectrum was softer than the ART-P spectrum; it was well described by a power
law with a photon index of 2.3 without any evidence of a high-energy cutoff.Comment: 8 pages, 3 figures. Accepted to publication in Astronomy Letter
X-Ray Spectral Variability of the Seyfert Galaxy NGC 4051 Observed with Suzaku
We report results from a Suzaku observation of the narrow-line Seyfert 1 NGC
4051. During our observation, large amplitude rapid variability is seen and the
averaged 2--10 keV flux is 8.1x10^-12 erg s^-1 cm^-2, which is several times
lower than the historical average. The X-ray spectrum hardens when the source
flux becomes lower, confirming the trend of spectral variability known for many
Seyfert 1 galaxies. The broad-band averaged spectrum and spectra in high and
low flux intervals are analyzed. The spectra are first fitted with a model
consisting of a power-law component, a reflection continuum originating in cold
matter, a blackbody component, two zones of ionized absorber, and several
Gaussian emission lines. The amount of reflection is rather large (R ~ 7, where
R=1 corresponds to reflection by an infinite slab), while the equivalent width
of the Fe-K line at 6.4 keV is modest (140 eV) for the averaged spectrum. We
then model the overall spectra by introducing partial covering for the
power-law component and reflection continuum independently. The column density
for the former is 1x10^23 cm^-2, while it is fixed at 1x10^24 cm-2 for the
latter. By comparing the spectra in different flux states, we identify the
causes of spectral variability. (abridged)Comment: 19 pages, 18 figures, accepted for publication in PASJ (Suzaku 3rd
special issue
Combined approach of density functional theory and quantum Monte Carlo method to electron correlation in dilute magnetic semiconductors
We present a realistic study for electronic and magnetic properties in dilute
magnetic semiconductor (Ga,Mn)As. A multi-orbital Haldane-Anderson model
parameterized by density-functional calculations is presented and solved with
the Hirsch-Fye quantum Monte Carlo algorithm. Results well reproduce
experimental results in the dilute limit. When the chemical potential is
located between the top of the valence band and an impurity bound state, a
long-range ferromagnetic correlations between the impurities, mediated by
antiferromagnetic impurity-host couplings, are drastically developed. We
observe an anisotropic character in local density of states at the
impurity-bound-state energy, which is consistent with the STM measurements. The
presented combined approach thus offers a firm starting point for realistic
calculations of the various family of dilute magnetic semiconductors.Comment: 5 pages, 4 figure
Percutaneous Cryoablation for the Treatment of Medically Inoperable Stage I Non-Small Cell Lung Cancer
BACKGROUND: To evaluate the midterm results of percutaneous cryoablation for medically inoperable stage I non-small cell lung cancer. METHODOLOGY/PRINCIPAL FINDINGS: Between January 2004 and June 2010, 160 patients underwent computer tomography guided percutaneous cryoablation for lung tumors at our institution. Of these patients, histologically proven stage I lung cancer patients with more than one year of follow-up, were retrospectively reviewed. All of these patients were considered to be medically inoperable with Charlson comorbidity index of 3 or greater. Follow-up was based primarily on computed tomography. There were 22 patients with 34 tumors who underwent 25 sessions of cryoablation treatment. Complications were pneumothoraces in 7 treatments (28%, chest tube required in one treatment), and pleural effusions in 8 treatments (31%). The observation period ranged from 12-68 months, average 29±19 months, median 23 months. Local tumor progression was observed in one tumor (3%). Mean local tumor progression-free interval was 69±2 months. One patient died of lung cancer progression at 68 months. Two patients died of acute exacerbations of idiopathic pulmonary fibrosis which were not considered to be directly associated with cryoablation, at 12 and 18 months, respectively. The overall 2- and 3-year survivals were 88% and 88%, respectively. Mean overall survival was 62±4 months. Median overall survival was 68 months. The disease-free 2- and 3-year survivals were 78% and 67%, respectively. Mean disease-free survival was 46±6 months. Pulmonary function tests were done in 16 patients (18 treatments) before and after cryoablation. Percentage of predicted vital capacity, and percentage of predicted forced expiratory volume in 1 second, did not differ significantly before and after cryoablation (93±23 versus 90±21, and 70±11 versus 70±12, respectively). CONCLUSIONS/SIGNIFICANCE: Although further accumulation of data is necessary regarding efficacy, cryoablation may be a feasible option in medically inoperable stage I lung cancer patients
7Be Solar Neutrino Measurement with KamLAND
We report a measurement of the neutrino-electron elastic scattering rate of
862 keV 7Be solar neutrinos based on a 165.4 kton-day exposure of KamLAND. The
observed rate is 582 +/- 90 (kton-day)^-1, which corresponds to a 862 keV 7Be
solar neutrino flux of (3.26 +/- 0.50) x 10^9 cm^-2s^-1, assuming a pure
electron flavor flux. Comparing this flux with the standard solar model
prediction and further assuming three flavor mixing, a nu_e survival
probability of 0.66 +/- 0.14 is determined from the KamLAND data. Utilizing a
global three flavor oscillation analysis, we obtain a total 7Be solar neutrino
flux of (5.82 +/- 0.98) x 10^9 cm^-2s^-1, which is consistent with the standard
solar model predictions.Comment: 8 pages, 6 figures, submitted to Phys. Rev.
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