Detection of highly ionized O and Ne absorption lines in the X-ray spectrum of 4U1820-303 in the globular cluster, NGC 6624

We searched for absorption lines of highly ionized O and Ne in the energy spectra of two Low-mass X-ray binaries, 4U1820-303 in the globular cluster NGC6624 and Cyg X-2, observed with the Chandra LETG, and detected O VII, O VIII and Ne IX absorption lines for 4U1820-303. The equivalent width of the O VII K alpha line was 1.19 +0.47/-0.30 eV (90 % errors) and the significance was 6.5 sigma. Absorption lines were not detected for Cyg X-2 with a 90 % upper limit on the equivalent width of 1.06 eV for O VII K alpha. The absorption lines observed in 4U1820-303 are likely due to hot interstellar medium, because O will be fully photo-ionized if the absorbing column is located close to the binary system. The velocity dispersion is restricted to b = 200 - 420 km/s from consistency between O VII K alpha and K beta lines, Ne/O abundance ratio, and H column density. The average temperature and the O VII density are respectively estimated to be log(T[K]) = 6.2 - 6.3 and n(OVII) = (0.7 - 2.3) x 10^{-6} cm^{-3}. The difference of O VII column densities for the two sources may be connected to the enhancement of the soft X-ray background (SXB) towards the Galactic bulge region. Using the polytrope model of hot gas to account for the SXB we corrected for the density gradient and estimated the midplane O VII density at the solar neighborhood. The scale height of hot gas is then estimated using the AGN absorption lines. It is suggested that a significant portion of both the AGN absorption lines and the high-latitude SXB emission lines can be explained by the hot gas in our Galaxy.Comment: Accepted for publication in ApJ. 7 pages, 9 eps figure

O and Ne K absorption edge structures and interstellar abundance towards Cyg X-2

We have studied the O and Ne absorption features in the X-ray spectrum of Cyg X-2 observed with the Chandra LETG. The O absorption edge is represented by the sum of three absorption-edge components within the limit of the energy resolution and the photon counting statistics. Two of them are due to the atomic O; their energies correspond to two distinct spin states of photo-ionized O atoms. The remaining edge component is considered to represent compound forms of oxide dust grains. Since Cyg X-2 is about 1.4 kpc above the galactic disk, the H column densities can be determined by radio (21 cm and CO emission line) and H alpha observations with relatively small uncertainties. Thus the O abundance relative to H can be determined from the absorption edges. We found that the dust scattering can affect the apparent depth of the edge of the compound forms. We determined the amplitude of the effect, which we consider is the largest possible correction factor. The ratio of column densities of O in atomic to compound forms and the O total abundance were respectively determined to be in the range 1.7^{+3.0}_{-0.9} to 2.8^{+5.1}_{-1.5} (ratio), and 0.63 +/- 0.12 solar to 0.74 +/- 0.14 solar (total), taking into account the uncertainties in the dust-scattering correction and in the ionized H column density. We also determined the Ne abundance from the absorption edge to be 0.75 +/- 0.20 solar. These abundance values are smaller than the widely-used solar values but consistent with the latest estimates of solar abundance.Comment: 20 pages, 3 figures, AASTeX format. Accepted for publication in Ap

Iodine-123 metaiodobenzylguanidine scintigraphic assessment of pulmonary vascular status in patients with chronic obstructive pulmonary disease

Background and objective: Lung uptake of iodine-123 metaiodobenzylguanidine ((123)I-MIBG) is used as an indicator of pulmonary endothelial function. Decreased lung uptake of (123)I-MIBG has been demonstrated in patients with COPD as compared with normal subjects. The present study was performed to examine the relationship between lung uptake of (123)I-MIBG and pulmonary artery pressure (Ppa) at rest and during exercise, in patients with COPD. Methods: (123)I-MIBG scintigraphy was performed in 19 patients with COPD. Anterior planar images were acquired 15 min after the injection of (123)I-MIBG, and the total lung to upper mediastinum ratio (LMR) was calculated for both lungs. Right heart catheters were used to monitor Ppa continuously at rest and during exercise. Exercise was performed on an electrically braked bicycle ergometer at a constant workload of 25 W for 3 min. Results: In COPD patients the LMR were not correlated with the pulmonary function parameters measured before exercise, including FEV(1), PaO(2), DL(CO), or Ppa at rest. However, the percentage increase in Ppa during exercise was significantly correlated with LMR. Conclusions: Evaluation of the kinetics of lung uptake of (123)I-MIBG may be a novel scintigraphic tool for the assessment of exercise-induced pulmonary hypertension in patients with COPD.ArticleRESPIROLOGY. 15(8):1215-1219 (2010)journal articl

Comparison of Distance of 6-min Walk Test and the Incremental Shuttle Walk Test with Lung Function or Quality of Life in Patients with Chronic Obstructive Pulmonary Disease

Article信州医学雑誌 61(2):57-64(2013)journal articl

Associations between the distance covered in the incremental shuttle walk test and lung function and health status in patients with chronic obstructive pulmonary disease

Background: Field walk tests such as the incremental shuttle walk test (ISWT) are simple tests for assessing the degree of disability in individuals with chronic obstructive pulmonary disease (COPD). In the present study, the correlations between exercise performance in the ISWT, lung function, and health status were examined in patients with COPD of varying seventies. Methods: A retrospective examination of 277 COPD patients was performed using the ISWT and lung function tests along with assessment of health status using St. George's Respiratory Questionnaire (SGRQ). In addition, we assessed the correlations between the walking distance, lung function parameters, and SGRQ scores. Results: ISWT distances were poorly correlated with lung function parameters and SGRQ scores in mild COPD patients. In contrast, ISWT distances were significantly correlated with pulmonary function parameters, such as vital capacity (%predicted) and forced expiratory volume in one second, and SGRQ scores in moderate and severe COPD patients. Conclusions: The ISWT is more independent of health status and pulmonary function in patients with mild COPD compared to moderate or severe cases. Therefore, the exercise capacity of patients with mild COPD should be estimated by the ISWT. (C) 2016 The Japanese Respiratory Society. Published by Elsevier B.V. All rights reserved.ArticleRESPIRATORY INVESTIGATION.55(1):33-38(2017)journal articl

A novel device (SD-101) with high accuracy for screening sleep apnoea-hypopnoea syndrome

Background and objective: The SD-101 is a non-restrictive, sheet-like medical device with an array of pressure sensors, to detect sleep-disordered breathing by sensing gravitational alterations in the body corresponding to respiratory movements. This study evaluated the accuracy of the SD-101 for screening sleep apnoea-hypopnoea syndrome (SAHS) by comparison with polysomnography. Methods: Nocturnal polysomnography and SD-101 monitoring were conducted simultaneously and compared in 201 patients with suspected SAHS (suspected SAHS group) and 165 male employees of a transport company (screening group). Results: Polysomnography revealed an AHI of = 60 events/h in 39, 35, 38, 68 and 21 subjects in the suspected SAHS group and 103, 34, 12, 12 and four subjects in the screening group, respectively. Central SAHS and obstructive SAHS were subsequently diagnosed in 11 (5.5%) and 135 (67.2%) of subjects in the suspected SAHS group and five (3.0%) and 39 (23.6%) of subjects in the screening group, respectively. Significant correlations were apparent between AHI and the respiratory disturbance index (RDI) measured with the SD-101 in both the suspected SAHS group (r = 0.88) and screening group (r = 0.92). Receiver operating characteristic curve analysis revealed 89.5% sensitivity and 85.8% specificity in identifying SAHS, using an RDI of 14.0 events/h. Conclusions: These findings suggest that the SD-101 is a useful device for screening SAHS.ArticleRESPIROLOGY. 14(8):1143-1150 (2009)journal articl

On the lack of strong O-line excess in the Coma cluster outskirts from Suzaku

About half of the baryons in the local Universe are thought to reside in the so-called warm-hot intergalactic medium (WHIM) at temperatures of 0.1-10 million K. Thermal soft excess emission in the spectrum of some cluster outskirts that contains OVII and/or OVIII emission lines is regarded as evidence of the WHIM, although the origin of the lines is controversial due to strong Galactic and solar system foreground emission. We observed the Coma-11 field, where the most prominent thermal soft excess has ever been reported, with Suzaku XIS in order to make clear the origin of the excess. We did not confirm OVII or OVIII excess emission. The OVII and OVIII intensity in Coma-11 is more than 5 sigma below that reported before and we obtained 2 sigma upper limits of 2.8 and 2.9 photons cm^-2 s^-1 sr^-1 for OVII and OVIII, respectively. The intensities are consistent with those in another field (Coma-7) that we measured, and with other measurements in the Coma outskirts (Coma-7 and X Com fields with XMM-Newton). We did not confirm the spatial variation within Coma outskirts. The strong oxygen emission lines previously reported are likely due to solar wind charge exchange.Comment: 5 pages, 3 figures. Accepted for publication in Ap

Chandra Observations of SDSS J1004+4112: Constraints on the Lensing Cluster and Anomalous X-Ray Flux Ratios of the Quadruply Imaged Quasar

We present results from Chandra observations of SDSS J1004+4112, a strongly lensed quasar system with a maximum image separation of 15". All four bright images of the quasar, as well as resolved X-ray emission originating from the lensing cluster, are clearly detected. The emission from the lensing cluster extends out to approximately 1.5 arcmin. We measure the bolometric X-ray luminosity and temperature of the lensing cluster to be 4.7e44 erg s^-1 and 6.4 keV, consistent with the luminosity-temperature relation for distant clusters. The mass estimated from the X-ray observation shows excellent agreement with the mass derived from gravitational lensing. The X-ray flux ratios of the quasar images differ markedly from the optical flux ratios, and the combined X-ray spectrum of the images possesses an unusually strong Fe Kalpha emission line, both of which are indicative of microlensing.Comment: 9 pages, 5 figures. Accepted for publication in ApJ. Version with high-quality color figures at http://cosmic.riken.jp/ota/publications/index.htm