bluuebunny/crossref_metadata_2025_split huggingface dataset:
Pulmonary Arterial Remodeling in Chronic Obstructive Pulmonary Disease is Lobe Dependent
Authors: Wrobel Jeremy P. , McLean Catriona A. , Thompson Bruce R. , Stuart‐Andrews Christopher R. , Paul Eldho , Snell Gregory I. , Williams Trevor J. 
Published: March 2014

Pulmonary arterial remodeling has been demonstrated in patients with severe chronic obstructive pulmonary disease (COPD), but it is not known whether lobar heterogeneity of remodeling occurs. Furthermore, the relationship between pulmonary hypertension (PH) and pulmonary arterial remodeling in COPD has not been established. Muscular pulmonary arterial remodeling in arteries 0.10–0.25 mm in diameter was assessed in COPD‐explanted lungs and autopsy controls. Remodeling was quantified as the percentage wall thickness to vessel diameter (%WT) using digital image analysis. Repeat measures mixed‐effects remodeling for %WT was performed according to lobar origin (upper and lower), muscular pulmonary arterial size (small, medium, and large), and echocardiography‐based pulmonary arterial pressure (no PH, mild PH, and moderate‐to‐severe PH). Lobar perfusion and emphysema indices were determined from ventilation‐perfusion and computed tomography scans, respectively. Overall, %WT was greater in 42 subjects with COPD than in 5 control subjects (P < 0.0001). Within the COPD group, %WT was greater in the upper lobes (P < 0.0001) and in the small muscular pulmonary arteries (P < 0.0001). Lobar differences were most pronounced in medium and large arteries. Lobar emphysema index was not associated with arterial remodeling. However, there was a significant positive relationship between the lobar perfusion index and pulmonary arterial remodeling (P = 0.024). The presence of PH on echocardiography showed only a trend to a small effect on lower lobe remodeling. The pattern of pulmonary arterial remodeling in COPD is complicated and lobe dependent. Differences in regional blood flow partially account for the lobar heterogeneity of pulmonary arterial remodeling in COPD.
Thermal Instability of Advection-Dominated Disks against Local Perturbations
Authors: Kato Shoji , Abramowicz Marek A. , Chen Xingming 
Published: March 2014

Abstract
Thermal instability is examined for advection-dominated one-temperature accretion disks. We consider axisymmetric perturbations with short wavelength in the radial direction. The viscosity is assumed to be sufficiently small for the vertical hydrostatic balance to hold in perturbed states. The type of viscosity is given either by the α-viscosity or by a diffusion-type stress tensor. Optically thick disks are found to be in general more unstable than optically thin ones. When thermal diffusion is present, optically thin disks become stable, but optically thick disks are still unstable. The instability of the advection-dominated disks is different from that of the geometrically thin disks without advection. In the case of no advection, the thermal mode behaves under no appreciable surface density change. In the case of advection-dominated disks, however, the thermal mode occurs with no appreciable pressure change (compared with the density change), when local perturbations are considered. The variations of angular momentum and of the surface density associated with the perturbations lead to a thermal instability. The astrophysical implications of this instability are briefly discussed.
Molecular Gas in the Poststarburst Galactic Nucleus of NGC 4736
Authors: Shioya Yasuhiro , Tosaki Tomoka , Ohyama Youichi , Murayama Takashi , Yamada Toru , Ishizuki Sumio , Taniguchi Yoshiaki 
Published: March 2014

Abstract
We present 12CO(J=1–0) observations of the poststarburst nucleus of NGC 4736. Although star in the nuclear region is currently inactive, there is a substantial amount of molecular gas, ∼ 107M⊙ , in the central ∼ 300 pc region. Comparing the observed molecular-gas surface density with the threshold gas density for star formation proposed by Kennicutt (1989, AAA 50.157.264), we find that the nuclear gas disk is stable for gravitational instability. We discuss possible scenarios for the nuclear starburst evolution of NGC 4736 in terms of either bar-driven instability fueling or minor-merger driven fueling (or triggering).
Discovery of a New SU UMa-Type Dwarf Nova, V 1028 Cygni
Authors: Baba Hajime , Kato Taichi , Nogami Daisaku , Hirata Ryuko , Matsumoto Katsura , Sadakane Kozo 
Published: March 2014

Abstract
V-band high-speed CCD photometry of V 1028 Cyg revealed that hump structures existed in the early stage of its 1995 July outburst. We obtained 0.06154 (± 0.00002) d as the best estimated period of superhumps. We confirmed that this dwarf nova belongs to the SU UMa stars. A re-brightening occurred after the superoutburst, and may be associated with a normal outburst. An analysis of the timings of superhump maxima showed clear evidence for an increase of the superhump period (Pdot = Ṗ/P) with 7.54 × 10−6. Only a few stars (AL Com, T Leo, SW UMa, etc.) are reported to have such an increase of the superhump period. At the end of the superoutburst, we detected that the amplitude of the superhumps increased considerably. Both of these properties are not typical features of ordinary SU UMa stars. The connection between the WZ Sge-type and the SU UMa-type dwarf novae is briefly discussed.
Discovery and Photometric Observation of the Optical Counterpart of a Possible Galactic Halo X-Ray Transient, XTE J1118+480
Authors: Uemura Makoto , Kato Taichi , Matsumoto Katsura , Yamaoka Hitoshi , Takamizawa Kesao , Sano Yasuo , Haseda Katsumi , Cook Lewis M. , Buczynski Denis , Masi Gianluca 
Published: March 2014

Abstract
We discovered an optical counterpart of about 13 mag of a soft X-ray transient, XTE J1118+480 on 2000 March 30. We performed astrometry and provided an accurate position of R.A. = 11h18m10s.85, Decl. = +48°02′12″.9. The outbursting object has been identified with a 18.8 mag star in the USNO catalog. Our pre-discovery data shows another outburst during 2000 January, again coinciding with an outburst detected in X-rays. Through CCD time-series photometry, we found the presence of a periodic variation with an amplitude of 0.055 mag and a period of 0.17078 ± 0.00004 d, which we consider to be a promising candidate of the orbital period. Because of the high galactic latitude and faint quiescence magnitude of 18.8, XTE J1118+480 is possibly the first firmly identified black hole candidate X-ray transient in the galactic halo.
A Spectral Index Map from VSOP Observations of Markarian 501
Authors: Edwards Philip G. , Giovannini Gabriele , Cotton William D. , Feretti Luigina , Fujisawa Kenta , Hirabayashi Hisashi , Lara Lucas , Venturi Tiziana 
Published: March 2014

Abstract
One of the features of VSOP observations is the ability to make contemporaneous, matched-resolution images at different frequencies in order to produce spectral index maps. We have combined VSOP observations made at 4.8 GHz on 1998 April 7 and 1.6 GHz on 1998 April 8 to make such a map of the variable X-ray and TeV gamma-ray source Mkn 501. The spectral index map reveals considerably more information than a single frequency total intensity image, and shows significant spectral variation along and across the milli-arcsecond scale jet. We interpret this in terms of models for the jet involving an inner fast spine and slower outer shear layer.
Dual-Frequency VSOP Observations of AO 0235+164
Authors: Frey Sándor , Gurvits Leonid I. , Altschuler Daniel R. , Davis Michael M. , Perillat Phil , Salter Chris J. , Aller Hugh D. , Aller Margo F. , Hirabayashi Hisashi 
Published: March 2014

Abstract
AO 0235+164 is a very compact, flat spectrum radio source identified as a BL Lac object at a redshift of z = 0.94. It is one of the most violently variable extragalactic objects at both optical and radio wavelengths. The radio structure of the source revealed by various ground-based VLBI observations is dominated by a nearly unresolved compact component at almost all available frequencies.
Dual-frequency space VLBI observations of AO 0235+164 were made with the VSOP mission in 1999 January-February. The array of the Japanese HALCA satellite and co-observing ground radio telescopes in Australia, Japan, China, and South Africa allowed us to study AO 0235+164 with an unprecedented angular resolution at frequencies of 1.6 and 5 GHz. We report on the sub-milliarcsecond structural properties of the source. The 5-GHz observations led to an estimate of TB&gt;5.8×1013 K for the rest-frame brightness temperature of the core, which is the highest value measured with VSOP to date.
ASCA Identification of SMC X-2 with the 2.37-s Pulsar Discovered by RXTE
Authors: Yokogawa Jun , Torii Ken’ichi , Kohmura Takayoshi , Koyama Katsuji 
Published: March 2014

Abstract
ASCA observed a new X-ray pulsar recently discovered with RXTE in the Small Magellanic Cloud, and detected coherent pulsations with a barycentric period of $2.37230 \pm 0.00004~\mathrm{s}$. The position is determined within a $\sim 30{{}^{\mathrm{\prime\prime}}}$ radius error, which is much more accurate than that reported with RXTE. Since the position error well overlaps a $\sim 20{{}^{\mathrm{\prime\prime}}}$ radius error of the SAS-3 transient source SMC X-2, and since the probability that an unrelated source falls in the error region by chance is estimated to be less than 0.1%, we conclude that SMC X-2 is the 2.37-s pulsar. The X-ray spectrum in the 0.7–10.0 keV band can be fitted with a model of a power-law continuum plus a fluorescent line from neutral or low-ionization iron. The pulse profile has a single peak below a few keV and gradually changes to be a double-peaked structure as the energy increases; in particular, the iron line band (6.0–7.0 keV) marginally shows a double-peaked profile similar to that of the higher energy band observed with RXTE.
Temperature Map and Iron Abundance of the Ophiuchus Cluster of Galaxies
Authors: Watanabe Manabu , Yamashita Koujun , Furuzawa Akihiro , Kunieda Hideyo , Tawara Yuzuru 
Published: March 2014

Abstract
We present an X-ray surface-brightness distribution and a temperature map of the Ophiuchus cluster of galaxies observed by ASCA. The Ophiuchus cluster is a nearby rich cluster located at $ z= 0.028$ having an angular extent of $\sim 1 {{}^{\circ }}$. The observations were made by five pointings that cover the whole cluster. After deconvolution with the ASCA complex response function, we obtained the surface-brightness distribution with an angular resolution of $ {2{}^{\mathrm {\prime }}}$ and a temperature map with $ {8{}^{\mathrm {\prime }}}$ resolution. The X-ray surface-brightness distribution shows a nearly spherically symmetric distribution, except for a $ 15\sigma$ image excess at the position of $ {10{}^{\mathrm {\prime }}}$ to the north of the cluster center. On the other hand, a hot region with a temperature $ &gt; 13 \,\mathrm{keV}$ is spread over a region of $ {20{}^{\mathrm {\prime }}}\times {30{}^{\mathrm {\prime }}}$ at $ {20{}^{\mathrm {\prime }}}$ to the west of the cluster center. Because these characteristics are similar to those of the Coma cluster, we conclude this cluster has never relaxed dynamically, and is also recently experienced a merger.
ASCA Observations of the Central Regions of M 31
Authors: Takahashi Hiromitsu , Okada Yuu , Kokubun Motohide , Makishima Kazuo 
Published: March 2014

Abstract
Using ASCA, spatially integrated X-ray spectra of the central regions of M 31 were studied. Data were accumulated over three different circular regions, with radii of $3', 6'$, and $12'$, all centered on the nucleus. The spectra are relatively similar among the three regions. In the energy range above 1.5 keV, the spectra are reproduced by a combination of a disk black-body component and a black-body component, implying that the emission mainly comes from an assembly of low-mass X-ray binaries. At energies below 1.5 keV, the spectra involve two additional softer components, expressed by thin-thermal plasma emission models of temperatures of $\sim 0.9 \,\mathrm{keV}$ and $\sim 0.3 \,\mathrm{keV}$. Over the central $12'$ (2.4 kpc) region and in the 0.5–10 keV energy band, the binary component has a luminosity of $2.6 \times 10^{39} \,\mathrm{erg} \,\mathrm{s}^{-1}$, while the two softer components both exhibit luminosities of $\sim 2 \times 10^{38} \,\mathrm{erg} \,\mathrm{s}^{-1}$. These results are compared with those from other missions, including Chandra and XMM-Newton in particular. A discussion is presented on the nature of the two softer spectral components besides the binary one.
Spiral Structure in WZ Sagittae around the 2001 Outburst Maximum
Authors: Baba Hajime , Sadakane Kozo , Norimoto Yuji , Ayani Kazuya , Ioroi Masayuki , Matsumoto Katsura , Nogami Daisaku , Makita Makoto , Kato Taichi 
Published: March 2014

Abstract
Intermediate-resolution phase-resolved spectra of WZ Sge were obtained on five consecutive nights (July 23–27) covering the initial stage of the 2001 superoutburst. Double-peaked emission lines of He II at 4686 Å, which were absent on July 23, emerged on July 24 together with emission lines of C III$/$ N III Bowen blend. Analyses of the He II emission lines using the Doppler tomography revealed an asymmetric spiral structure on the accretion disk. This finding demonstrates that spiral shocks with a very short orbital period can arise during the initial stage of an outburst and may be present in all SU UMa stars.
Rapid Optical Fluctuations in the Black Hole Binary V4641 Sagittarii
Authors: Uemura Makoto , Kato Taichi , Ishioka Ryoko , Tanabe Kenji , Kiyota Seiichiro , Monard Berto , Stubbings Rod , Nelson Peter , Richards Tom , Bailyn Charles , Santallo Roland 
Published: March 2014

Abstract
We report on unprecedented short-term variations detected in the optical flux from the black hole binary system, V4641 Sgr. The amplitudes of the optical fluctuations were larger at longer time scales, and surprisingly reached $ \sim 60\%$ around a period of $ \sim10 \,\mathrm{min}$. The power spectra of the fluctuations are characterized by a power law ($ \propto f^{-\alpha},\; \alpha \sim-1.7$). It is the first case for black hole binaries that the optical emission was revealed to show short-term and large-amplitude variations given by such a power spectrum. The optical emission from black hole binaries is generally dominated by the emission from the outer portion of an accretion disc. The rapid optical fluctuations, however, indicate that the emission from an inner accretion region significantly contributes to the optical flux. In this case, cyclo-synchrotron emission associated with various scales of magnetic flares is the most promising mechanism for the violently variable optical emission.
PASJ: Publ. Astron. Soc. Japan 54, L79-L82, 2002 October 25 (C) 2002. Astronomical Society of Japan
Interferometric Observations of Formaldehyde in the Protoplanetary Disk around LkCa 15
Authors: Aikawa Yuri , Momose Munetake , Thi Wing-Fai , van Zadelhoff Gerd-Jan , Qi Chunhua , Blake Geoffrey A. , van Dishoeck Ewine F. 
Published: March 2014

Abstract
Emission from the $2_{12} \hbox{-} 1_{11}$ line of $\mathrm{H}_2\mathrm{CO}$ has been detected and marginally resolved toward LkCa 15 by the Nobeyama Millimeter Array. The column density of $\mathrm{H}_2\mathrm{CO}$ is higher than that observed in DM Tau and than predicted by theoretical models of disk chemistry; also, the line-intensity profile is less centrally peaked than that for CO. A similar behavior is observed in other organic gaseous molecules in the LkCa 15 disk.
Silhouette of a Dressed Black Hole
Authors: Fukue Jun 
Published: March 2014

Abstract
In the case of the traditional standard disk with an inner radius of $3 \,r_{\mathrm{g}}$ (three Schwarzschild radii) around the Schwarzschild black hole, there appears to be a dark central shadow with a radius of about $3 \,r_{\mathrm{g}}$. In the case of a disk extending down to $1 \,r_{\mathrm{g}}$, on the other hand, we found that the radius of the dark shadow is about $2 \,r_{\mathrm{g}}$. These shadow sizes are different from that obtained by Falcke et al. (2000, AAA 073.155.002), where the shadow radius is about $2.6 \,r_{\mathrm{g}}$. This is because they considered an optically-thin spherical envelope, while we assumed an optically-thick luminous disk. In addition, we found that in an edge-on view the central shadow becomes a semicircle due to the projection effect. Such a silhouette of a dressed black hole throws light on the space-time structure of the hole as well as the type of surrounding disk.
Review of Discrete X-Ray Sources in the Small Magellanic Cloud: Summary of the ASCA Results and Implication on the Recent Star-Forming Activity
Authors: Yokogawa Jun , Imanishi Kensuke , Tsujimoto Masahiro , Koyama Katsuji , Nishiuchi Mamiko 
Published: March 2014

Abstract
We made 22 observations on the Small Magellanic Cloud (SMC) and covered full regions of the main body and the eastern wing by the end of the ASCA mission. We detected 106 discrete sources with a criterion of $\mathrm{S/N} \gt 5$$\mathrm{S/N} \gt 5$ and performed systematic analyses on all of the sources. We determined the source positions with an $\sim {40{}^{\mathrm {\prime \prime }}}$ error radius (90% confidence) for sources detected in the central ${20{}^{\mathrm {\prime }}}$ radius of the GIS. We detected coherent pulsations from 17 sources. Among them, eight were newly discovered during this study. We classified most of these pulsars as X-ray binary pulsars (XBPs) based on their properties, such as the flux variability and the existence of an optical counterpart. We detected X-ray emission from eight supernova remnants (SNRs). Among them, five SNRs showed emission lines in their spectra, hence we regarded the five as thermal SNRs. We found that XBPs and thermal SNRs in the SMC can be clearly separated by their spectral hardness ratio. Applying this empirical law to faint (thus unclassified) sources, we found 19 XBP candidates and four thermal SNR candidates. We also found several tens of candidates for active galactic nuclei, both from the hardness ratio and the $\log N \hbox{--}\log S$ relation of extragalactic sources. Based on these ASCA results and further information from ROSAT, SAX, RXTE, CGRO, Chandra, and XMM-Newton, we compiled comprehensive catalogues of discrete X-ray sources in the Small Magellanic Cloud. Using the catalogues, we derived the spatial distributions of XBPs and SNRs. XBPs and SNRs were found to be concentrated in the main body and eastern wing, which resembles the distribution of young stars with ages of $\sim 2 \times 10^7 \,\mathrm{yr}$. By comparing the source populations in the SMC and our Galaxy, we suggest that the star-forming rate (per unit mass) in the SMC was much higher than the Galaxy $\sim 10^7 \,\mathrm{yr}$ ago. We also discuss the recent change of the star-forming rate in the SMC.
SiO Maser Survey of Cold IRAS Sources
Authors: Nakashima Jun-ichi , Deguchi Shuji 
Published: March 2014

Abstract
We present the results of observations of cold IRAS sources in the Galactic disk area, $-10^{\circ} &lt; l &lt; 100^{\circ}$ and $\vert b\vert &lt; 5^{\circ}$, in the SiO $J = 1\hbox{--}0$, $v = 1$ and 2 maser lines. SiO masers were detected in 51 out of 143 observed sources; 45 were new detections in SiO masers. The selected IRAS sources were objects with dust temperatures of between 160 and 280 K. According to a confirmation using 2MASS near-infrared images, a majority of the sample are AGB or post-AGB stars, although dense cores in the star-forming regions (or dusty H ii regions) are involved in part of the sample. Among new detections, two were candidates for post-AGB stars: IRAS 18450$-$0148 (W43 A), and 19312$+$1950. We found that the intensity ratios of the SiO $J = 1\hbox{--}0$, $v = 2$ to the $v = 1$ line of the objects clearly correlate with those IRAS colors. The detection rates of SiO masers tend to increase toward the Galactic center as well as the cases of previous SiO maser surveys of typical AGB stars. No strong associations of the objects to the spiral arms were found. The radial-velocity dispersion of the present sample is comparable with the dispersion of the SiO maser sample of typical AGB stars. These facts suggest that the present sample of cold IRAS sources with SiO masers has a kinematic property very similar to that of typical AGB stars.
Observational Evidence for a High-Energy Compton Cloud in GRO J1655-40 under a High Accretion Rate
Authors: Kobayashi Yoshihito , Kubota Aya , Nakazawa Kazuhiro , Takahashi Tadayuki , Makishima Kazuo 
Published: March 2014

Abstract
Observational results on GRO J1655$-$40 are reported, based on the X-ray spectra obtained with the PCA and the HEXTE on-board RXTE during its 1996–1997 outburst. By referring to the 40–150 keV X-ray luminosity, $L_{40 \hbox{--} 150}$, six typical spectra were selected and analyzed. When $L_{40 \hbox{--} 150}$ is sufficiently below $\sim 5 \times 10^{36} \mathrm{erg} \,\mathrm{s}^{-1}$ (assuming a distance of 3.2 kpc and an isotropic emission), the 3–150 keV PCA/HEXTE spectra are well described by a standard spectral model consisting of an optically-thick disk spectrum and a power-law tail. When $L_{40 \hbox{--} 150}$ exceeds $5 \times 10^{36} \,\mathrm{erg} \,\mathrm{s}^{-1}$, the standard model fails to reproduce the joint spectrum, due to a mild turn-over in the HEXTE spectrum. Successful fits are recovered when the power-law component is replaced by a broken power-law model with the break energy at $\sim 40 \,\mathrm{keV}$, or by an exponentially cutoff power-law model with the cutoff energy at 190–300 keV. The fits are further improved by employing a thermal Comptonization component, wherein the electron temperature and optical depth of the Compton cloud are estimated to be 70–85 keV and 0.45–0.65, respectively. These results provide strong evidence for the existence of thermal high-energy electrons, and reconfirm the picture of strong disk Comptonization.
Evidence for Jet Collimation in SS 433 with the Chandra HETGS
Authors: Namiki Masaaki , Kawai Nobuyuki , Kotani Taro , Makishima Kazuo 
Published: March 2014

Abstract
High-resolution X-ray spectra of SS 433 obtained after a binary egress with the Chandra High Energy Transmission Grating Spectrometer (HETGS) were studied. Many Doppler-shifted X-ray emission lines from highly ionized elements were detected. The initial temperature of the jets is estimated to be 20 keV. The lines are found to generally be broader than the instrumental resolution. The widths of the Fe xxv$\mathrm{K}\alpha$ and Si xiii$\mathrm{K}\alpha$ lines correspond to velocity dispersions of $2100^{+600}_{-340} \,\mathrm{km} \,\mathrm{s}^{-1}$ and $840^{+180}_{-150} \,\mathrm{km} \,\mathrm{s}^{-1}$ respectively, in terms of Gaussian sigma. Neither the measured line widths nor their dependence on the atomic number can be explained by thermal broadening alone. Alternative explanations of the observed line widths are discussed, including in particular a progressive jet collimation along its axis.