Studies of the diffuse x-ray—emitting gas in galaxy clusters have provided powerful constraints on cosmological parameters and insights into plasma astrophysics. However, measurements of the faint ...cluster outskirts have become possible only recently. Using data from the Suzaku x-ray telescope, we determined an accurate, spatially resolved census of the gas, metals, and dark matter out to the edge of the Perseus Cluster. Contrary to previous results, our measurements of the cluster baryon fraction are consistent with the expected universal value at half of the virial radius. The apparent baryon fraction exceeds the cosmic mean at larger radii, suggesting a clumpy distribution of the gas, which is important for understanding the ongoing growth of clusters from the surrounding cosmic web.
Background
Laparoscopic wedge resection of the stomach is an ideal procedure if the gastric gastrointestinal stromal tumors (GISTs) are located in the extraluminal stomach. When the tumor is located ...in the intraluminal stomach, two minimally invasive surgical procedures involving laparoscopic and endoscopic cooperative surgery (LECS) or endoscopic intragastric surgery (EIGS) are frequently performed. To date, there have been no comparative studies of LECS and EIGS in patients with intraluminal gastric GISTs regarding short-term and long-term outcomes. The aim of this study was to compare the safety and feasibility of LECS and EIGS in patients with intraluminal gastric GISTs.
Methods
This was a single-center retrospective study of 46 consecutive patients with intraluminal gastric GISTs who underwent minimally invasive surgery. LECS (
n
= 21) was performed between 2013 and 2015 and EIGS (
n
= 26) was performed between 2001 and 2013.
Results
The overall incidence of perioperative complications was significantly higher in the EIGS group than in the LECS group (40 vs 4.8%;
P
= 0.006). In the EIGS group, three patients with intraoperative gastric mucosal injury were followed-up throughout surgical repair (12%). An esophageal tear was found in one patient during oral removal of tumor (4%). Postoperative gastric hemorrhage occurred in three patients (12%) and superficial surgical site infection was observed in three patients (12%). In the LECS group, anastomotic leakage requiring additional drainage was observed in one patient (4.8%). EIGS had less favorable results regarding median time to resumption of first oral intake (2 vs 1 days;
P
= 0.005). Two of 46 patients (4.3%), including one patient who underwent LECS and one patient who underwent EIGS developed recurrence. No cause-specific deaths were observed.
Conclusion
LECS is a feasible and safe procedure for intraluminal gastric GISTs with regard to both short-term surgical and long-term oncological outcomes. Registration number: UMIN000026631.
We observed outer regions of a bright cluster of galaxies, A 2142, with Suzaku. Temperature and brightness structures were measured out to the virial radius (
$r_{200}$
) with good sensitivity. We ...confirmed a temperature drop from 9 keV around the cluster center to about 3.5 keV at
$r_{200}$
, with the density profile well approximated by the
$\beta$
-model with
$\beta$
$=$
0.85. Within 0.4
$r_{200}$
, the entropy profile agrees with
$r^{1.1}$
, as predicted by the accretion shock model. The entropy slope becomes flatter in the outer region and negative around
$r_{200}$
. These features suggest that the intracluster medium in the outer region is out of thermal equilibrium. Since the relaxation timescale of electron-ion Coulomb collisions is expected to be longer than the elapsed time after shock heating at
$r_{200}$
, one plausible reason for the low entropy is a low electron temperature compared to that of ions. Other possible explanations would be gas clumpiness, turbulence and bulk motions of the ICM. We also searched for a warm-hot intergalactic medium around
$r_{200}$
, and set an upper limit on the oxygen line intensity. Assuming a line-of-sight depth of 2 Mpc and oxygen abundance of 0.1 solar, the upper limit of an overdensity is calculated to be 280 or 380, depending on the foreground assumption.
We report an apparent detection of the C VI 4p to 1s transition line at 459 eV, during a long-term enhancement (LTE) in the Suzaku north ecliptic pole observation of 2005 September 2. The observed ...line intensity is comparable to that of the C VI 2p to 1s line at 367 eV. This is strong evidence for the charge-exchange process. In addition, O VII, O VIII, Ne X, and Mg XI lines showed clear enhancements. There are also features in the 750–900–eV range that could be due to some combination of Fe L lines, higher order transitions of O VIII (3p to 1s and 6p to 1s), and a Ne IX line. From the correlation of the X-ray intensity with the solar-wind flux on time scales of about half a day, and from the short-term (
$\sim 10 \,\mathrm{minutes}$
) variations of the X-ray intensity, these lines most likely arise from solar-wind heavy ions interacting with neutral material in the Earth’s magnetosheath. A hard power-law component is also necessary to explain the LTE spectrum. Its origin is not yet known. Our results indicate that solar activity can significantly contaminate Suzaku cosmic X-ray spectra below
$\sim 1 \,\mathrm{keV}$
. Recommendations are provided for recognizing such contamination in observations of extended sources.
•SXS Dewar has hybrid cooling system combining liquid helium and cryocoolers.•SXS Dewar has cryogen free operation mode without liquid helium.•Cold mass in 4 K area is 35 kg.•He tank temperature ...reached to 4.5 K in 37 days.•Maximum power was 264 W in total.
Soft X-ray Spectrometer instrument (SXS) is one of the primary scientific instruments of ASTRO-H. SXS has a cold detector that is cooled to 50 mK by using a multi-stage Adiabatic Demagnetization Refrigerator (ADR). SXS Dewar containing ADR provides 1.3 K heat sink by using liquid helium in nominal operation. After liquid helium is dried up, 4 K heat sink is provided by using mechanical coolers. Both nominal operation and cryogen free operation were successfully demonstrated. This paper describes the test result of cryogen free operation and cool-down performance from room temperature by using only mechanical coolers without liquid helium. The coolers on the Dewar cooled down cold mass from around 300 K to 4 K with 260 W electric power in 40 days. Cold mass is 35 kg in 4 K area including the helium tank, ADR and detector assembly.
We present a structural study of the hot ISM in the Galactic halo along the sight line toward the bright active galactic nucleus Mkn 421. The O vii and O viii absorption lines were measured with the ...Low Energy Transmission Grating Spectrograph aboard Chandra toward Mkn 421; the O vii and O viii emission lines were observed in the adjacent fields of the line of sight with the X-ray Imaging Spectrometer aboard Suzaku. We jointly analyzed the absorption and emission spectra while assuming exponential distributions of the gas temperature and density from the Galactic plane, and constrained the temperature and density at the plane to be (
$3.2^{+0.6}_{-0.7}$
) × 106 K and (
$1.2^{+0.5}_{-0.4}$
) × 10−3 cm−3, with a scale heights of
$1.6^{+1.7}_{-0.7}$
kpc and > 2.8 kpc, respectively. The results are consistent with those obtained in the LMC X-3 direction and the PKS 2155−304 direction, describing a thick disk-like hot gas with its height of a few kpc from the Galactic plane.
The X-Ray Spectrometer (XRS) instrument of Suzaku provided the first measurement of the non-X-ray background (NXB) of an X-ray calorimeter spectrometer, but the data set was limited. The Soft X-ray ...Spectrometer (SXS) instrument of Hitomi was able to provide a more detailed picture of X-ray calorimeter background, with more than 360 ks of data while pointed at the Earth, and a comparable amount of blank-sky data. These data are important not only for analyzing SXS science data, but also for categorizing the contributions to the NXB in X-ray calorimeters as a class. In this paper, we present the contributions to the SXS NXB, the types and effectiveness of the screening, the interaction of the screening with the broad-band redistribution, and the residual background spectrum as a function of magnetic cut-off rigidity. The orbit-averaged SXS NXB in the range 0.3-12 keV was 4 × 10(exp −2) counts s(exp −1) -sq cm. This very low background in combination with groundbreaking spectral resolution gave SXS unprecedented sensitivity to weak spectral lines.
•We developed a hybrid cooling system by using liquid helium, mechanical cryocoolers.•The final liquid helium filling was performed successfully just before launch.•The cooling performance was as ...expected, and it could have fulfilled the lifetime requirement of three years in orbit.
ASTRO-H was an X-ray astronomy satellite that the Japan Aerospace Exploration Agency (JAXA) developed to study the evolution of the universe and physical phenomena yet to be discovered. The primary scientific instrument of ASTRO-H was the Soft X-ray Spectrometer (SXS). Its detectors were to be cooled to 50 m K using a complex cryogenic system with a multistage adiabatic demagnetization refrigerator (ADR) developed by the National Aeronautics and Space Administration (NASA), and a cryogenic system developed by Sumitomo Heavy Industries, Ltd. (SHI). SHI’s cryogenic system was required to cool the ADR’s heatsink to 1.3 K or less in orbit for three years or longer. To meet these requirements, SHI developed a hybrid cryogenic system consisting of a liquid helium tank, a 4 K Joule-Thomson cooler, and two two-stage Stirling coolers.
ASTRO-H was launched from Tanegashima Space Center on February 17, 2016. The initial operation of the SXS cryogenic system in orbit was completed successfully. The cooling performance was as expected and could have exceeded the lifetime requirement of three years.
This paper describes results of ground tests, results of top-off filling of superfluid liquid helium just before launch, and cooling performance in orbit.
Although about 40% of the soft X-ray background emission in 0.4 to 1 keV range has extragalactic origins and thus is totally blocked by the galactic absorption in midplane directions, it decreases at ...most by about 20% in midplane. Suzaku observation of the direction, (
$\ell$
,
$b$
)
$=$
(235
$^\circ$
, 0
$^\circ$
), showed an O vii
${\rm K} \alpha$
emission intensity comparable with that of the MBM-12 on cloud Suzaku observation, but revealed a narrow bump peaked at
$\sim$
0.9 keV. The latter component is partly filling the decrease of the extragalactic component in midplane. The feature can be well represented by a thin thermal emission with a temperature of about 0.8 keV. Because of the high pressure implied for spatially extended hot gas, the emission is likely a sum of unresolved faint sources. We consider a large fraction of the emission originates from faint dM stars. We constructed a model spectrum for spatially unresolved dM stars that consistently explains the observed spectrum and the surface brightness. The model also suggests that the emission from dM stars decreases very rapidly with increasing
$b$
, and thus that it cannot compensate entirely the decrease of the extragalactic component at
$b$
$\sim$
2
$^\circ$
–10
$^\circ$
.
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