358 research outputs found

    Low State of the X-ray Burster SLX 1732-304 in the Globular Cluster Terzan 1 According to RXTE Data

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    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

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    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

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    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

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    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

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    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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