65 research outputs found
Study of the accreting pulsar 4U 0115+634 with a bulk and thermal Comptonization model
Highly magnetized pulsars accreting matter in a binary system are bright
sources in the X-ray band (0.1-100 keV). Despite the early comprehension of the
basic emission mechanism, their spectral energy distribution is generally
described by phenomenological or simplified models. We propose a study of the
spectral emission from the high mass X-ray binary pulsar 4U 0115+634 by means
of thermal and bulk Comptonization models based on the physical properties of
such objects. For this purpose, we analyze the BeppoSAX data in the energy
range 0.7-100 keV of the 1999 giant outburst, 12 days after the maximum. We
model the spectral energy distribution of the system using a two-component
continuum. At higher energy, above ~7 keV, the emission is due to thermal and
bulk Comptonization of the seed photons produced by cyclotron cooling of the
accretion column, and at lower energy, the emission is due to thermal
Comptonization of a blackbody source in a diffuse halo close to the stellar
surface. From the best fit parameters, we argue that the cyclotron emission is
produced ~1.7 km above the stellar surface, and escapes from the column near
its base, where the absorption features are generated by the interaction with
the magnetic field in a surrounding halo. We find that in 4U 0115+634, the
observed spectrum is dominated by reprocessed cyclotron radiation, whereas in
other bright sources with stronger magnetic fields such as Her X-1, the
spectrum is dominated by reprocessed bremsstrahlung.Comment: 12 pages, accepted for publication on Astronomy and Astrophysic
4U 0115+63 from RXTE and INTEGRAL Data: Pulse Profile and Cyclotron Line Energy
We analyze the observations of the transient X-ray pulsar 4U 0115+63 with the
RXTE and INTEGRAL observatories in a wide X-ray (3-100 keV) energy band during
its intense outbursts in 1999 and 2004. The energy of the fundamental harmonic
of the cyclotron resonance absorption line near the maximum of the X-ray flux
from the source (luminosity range 5x10^{37} - 2x10^{38} erg/s) is ~11 keV. When
the pulsar luminosity falls below ~5x10^{37} erg/s, the energy of the
fundamental harmonic is displaced sharply toward the high energies, up to ~16
keV. Under the assumption of a dipole magnetic field configuration, this change
in cyclotron harmonic energy corresponds to a decrease in the height of the
emitting region by ~2 km, while other spectral parameters, in particular, the
cutoff energy, remain essentially constant. At a luminosity ~7x10^{37} erg/s,
four almost equidistant cyclotron line harmonics are clearly seen in the
spectrum. This suggests that either the region where the emission originates is
compact or the emergent spectrum from different (in height) segments of the
accretion column is uniform. We have found significant pulse profile variations
with energy, luminosity, and time. In particular, we show that the profile
variations from pulse to pulse are not reduced to a simple modulation of the
accretion rate specified by external conditions.Comment: 30 pages, 13 figures, Astronomy Letters, 33, 368 (2007
INSIG2 gene rs7566605 polymorphism is associated with severe obesity in Japanese
The single nucleotide polymorphism (SNP) rs7566605 in the upstream region of the insulin-induced gene 2 (INSIG2) is associated with the obesity phenotype in many Caucasian populations. In Japanese, this association with the obesity phenotype is not clear. To investigate the relationship between rs7566605 and obesity in Japanese, we genotyped rs7566605 from severely obese subjects [n = 908, body mass index (BMI) ≥ 30 kg/m2] and normal-weight control subjects (n = 1495, BMI < 25 kg/m2). A case–control association analysis revealed that rs7566605 was significantly associated with obesity in Japanese. The P value in the minor allele recessive mode was 0.00020, and the odds ratio (OR) adjusted for gender and age was 1.61 [95% confidential interval (CI) = 1.24–2.09]. Obesity-associated phenotypes, which included the level of BMI, plasma glucose, hemoglobin A1c, total cholesterol, triglycerides, high-density lipoprotein (HDL) cholesterol, and blood pressure, were not associated with the rs7566605 genotype. Thus, rs7566605 in the upstream region of the INSIG2 gene was found to be associated with obesity, i.e., severe obesity, in Japanese
Stage-based treatment for thymoma in due consideration of thymectomy: a single-center experience and comparison with the literature
BACKGROUND: Thymomas represent an uncommon and heterogeneous group of intrathoracic malignancies which require different treatments corresponding to their individual tumor stage. The objective of this study was to review the efficacy of our applied stage-based treatment for thymoma in due consideration of thymectomy. METHODS: This is a single-center, institutional review board-approved retrospective study of 50 consecutive patients with thymoma treated at our division within 10 years. RESULTS: There were 29 women (58 %) and 21 men (42 %), mean age 58.3 years. Twenty nine (58 %) had clinical symptoms and 14 (28 %) had myasthenia gravis. Forty-five patients (90 %) underwent thymectomy and complete resection was done in 42 cases (93.3 %). Histologic results were 6 subtype A, 5 AB, 8 B1, 12 B2, 12 B3, and 7 C. The Masaoka staging system revealed 20 stage I, 18 stage II, 6 stage III, and 6 stage IV. Two patients had neoadjuvant therapy and 25 received postoperative treatment. Five (11.1 %) had tumor recurrence, treated with re-resection. The 5-year disease-free survival was 91.5 %. Two patients died of tumor progression and three died of other causes (10 %). The 5-year overall survival was 82.3 % and the median survival time was 92.1 months. The 5-year survival rate after thymectomy was 87.2 % and the median survival was 92.1 months. CONCLUSIONS: Complete resection still remains the mainstay in the treatment of non-metastatic thymoma and should be performed whenever feasible. Close multidisciplinary teamwork is mandatory to optimize the neurologic outcome and to prolong postoperative survival
Low glucose-1, 6-bisphosphate and high fructose-2, 6-bisphosphate concentrations in muscles of patients with glycogenosis types VII and V
A Genetic Defect in Muscle Phosphofructokinase Deficiency, A Typical Clinical Entity Presenting Myogenic Hyperuricemia
Stacking strategy for acquisition of an ACROSS transfer function with large signal-to-noise ratio
EM-ACROSS System and the Corresponding Tensor Transfer Functions in the Diffusion Field Region
Hand-Assisted Thoracoscopic Surgery for Pulmonary Metastasectomy through Sternocostal Triangle Access: Superiority in Detection of Non-Imaged Pulmonary Nodules
A Decomposition Method of the Electromagnetic Transfer Function Using Ray Model and Autoregressive-type Model : the Case of a Horizontal Layered Structure
EM ACROSS (electromagnetic accurately controlled routinely operated signal system) is one of electromagnetic exploration methods. In this method, an accurately controlled continuous signal is transmitted and the transfer function of the transmitted and the received electromagnetic fields is observed. Because the transfer function is required to be decomposed to extract information of electromagnetic structure, we here developed such a processing technique. We studied the case of a horizontal structure consisting of isotropic homogeneous layers. We introduced a ray model to describe the transfer function, and then applied an AR (autoregressive)-type model to describe the ray model as a discrete linear system. We further developed a practical algorithm to estimate the parameters of the AR-type model. The present technique is demonstrated to work well in a simple numerical experiment, and we could estimate electric structure easily using the decomposed transfer function
- …