Flight Performance of the AKARI Cryogenic System

We describe the flight performance of the cryogenic system of the infrared astronomical satellite AKARI, which was successfully launched on 2006 February 21 (UT). AKARI carries a 68.5 cm telescope together with two focal plane instruments, Infrared Cameras (IRC) and Far Infrared Surveyor (FIS), all of which are cooled down to cryogenic temperature to achieve superior sensitivity. The AKARI cryogenic system is a unique hybrid system, which consists of cryogen (liquid helium) and mechanical coolers (2-stage Stirling coolers). With the help of the mechanical coolers, 179 L (26.0 kg) of super-fluid liquid helium can keep the instruments cryogenically cooled for more than 500 days. The on-orbit performance of the AKARI cryogenics is consistent with the design and pre-flight test, and the boil-off gas flow rate is as small as 0.32 mg/s. We observed the increase of the major axis of the AKARI orbit, which can be explained by the thrust due to thermal pressure of vented helium gas.Comment: 19 pages, 10 figures, and 6 tables. Accepted for publication in the AKARI special issue of the Publications of the Astronomical Society of Japa

Hot debris dust around HD 106797

Photometry of the A0 V main-sequence star HD 106797 with AKARI and Gemini/T-ReCS is used to detect excess emission over the expected stellar photospheric emission between 10 and 20 micron, which is best attributed to hot circumstellar debris dust surrounding the star. The temperature of the debris dust is derived as Td ~ 190 K by assuming that the excess emission is approximated by a single temperature blackbody. The derived temperature suggests that the inner radius of the debris disk is ~ 14 AU. The fractional luminosity of the debris disk is 1000 times brighter than that of our own zodiacal cloud. The existence of such a large amount of hot dust around HD 106797 cannot be accounted for by a simple model of the steady state evolution of a debris disk due to collisions, and it is likely that transient events play a significant role. Our data also show a narrow spectral feature between 11 and 12 micron attributable to crystalline silicates, suggesting that dust heating has occurred during the formation and evolution of the debris disk of HD 106797.Comment: Accepted to ApJ Letters, 8 pages, 2 figure

Integrated education of gross anatomy and CT radiology for current advances in medicine

It is essential to learn human anatomy in 3D for advanced medicine. We designed such an education system by integrating anatomy dissection with diagnostic CT radiology. Cadavers were scanned by CT, and students consulted the postmortem CT images while dissecting the cadaver to gain a better understanding of 3D human anatomy and diagnostic radiology. Students used handheld DICOM viewers at the bench-side (OsiriX on iPod touch). Students had lectures and workshops on diagnostic radiology, and study assignments where they discussed findings in anatomy labs in comparison with CT radiology. This teaching method for gross anatomy was used from 2009, and yielded positive students’ perspectives, and significant improvements in radiology skills at clinical courses.This is the pre-peer reviewed version of the following article: Tohru Murakami, Yuki Tajika, Hitoshi Ueno, Sachiko Awata, Satoshi Hirasawa, Maki Sugimoto, Yoshihiko Kominato, Yoshito Tsushima, Keigo Endo, and Hiroshi Yorifuji. An integrated teaching method of gross anatomy and computed tomography radiology. Anat Sci Educ, 2014, which has been published in final form at http://onlinelibrary.wiley.com/ doi/10.1002/ase.1430/abstract

Metastatic Renal Cell Carcinoma to the Left Sphenoid Sinus: A Case Report in Light of the Literature

A 79-year-old Japanese woman presented with a rare case of metastatic renal cell carcinoma to the left sphenoid sinus with left nasal bleeding. She had previously had right radical nephrectomy for renal cell carcinoma at the age of 64 years and brain and spinal cord infarction at 74 years. Endoscopic examination revealed no mass in the nasal cavity. CT and MRI revealed a tumor in the left sphenoid sinus. The size of the tumor increased gradually from 12 to 15 years after the radical nephrectomy. Complete resection with endoscopic surgery was performed without preoperative embolization. The tumor cells had clear cytoplasm and were arranged in a trabecular pattern lined by a layer of endothelial cells. These findings were identical to the pathological findings of the surgical specimen of the renal cell carcinoma from 15 years previous. A pathological diagnosis of metastatic renal cell carcinoma of clear cell type (grade 1) was made. PET-CT demonstrated no metastasis. The patient’s condition was successfully managed with excision of the tumor, and she remains well with no evidence of recurrence and metastasis 36 months after treatment. Metastatic renal cell carcinoma to the sphenoid sinus is rare, but it might be considered in the differential diagnosis of masses in the paranasal sinus even long after initial treatment of renal cancer

Immunoglobulin G4-Related Hepatic Inflammatory Pseudotumor Diagnosed with Endoscopic Ultrasound-Guided Fine-Needle Biopsy

A 71-year-old man with obstructive jaundice was referred to our department. He underwent cholangiojejunostomy 15 years ago for palliative drainage. At that time, he had obstructive jaundice caused by an unresectable pancreatic head tumor. Contrast-enhanced computed tomography (CE-CT) now revealed a mass with low enhancement in the hepatic hilum that occluded the hilar bile duct and infiltrated extensively along the portal vein and hepatic artery. CE-CT also showed marked atrophy of the left hepatic lobe. No swelling or tumors were observed in the pancreas. Serum immunoglobulin G4 (IgG4) levels were as high as 465 mg/dL. Endoscopic ultrasound-guided fine-needle biopsy (EUS-FNB) was performed targeting the hepatic hilar lesion. Immunohistological results of the biopsy specimens suggested that the lesion was an IgG4-related hepatic inflammatory pseudotumor (IPT) with no atypical cells. Steroid treatment resulted in rapid clinical improvement. This case suggested the usefulness of EUS-FNB for diagnosing IgG4-related hepatic hilar IPT

SPICA infrared coronagraph for the direct observation of exo-planets

We present a MIR coronagraph to target the direct observation of extrasolar planets for SPICA, in which a coronagraph is currently regarded as an option of the focal plane instruments. The primary target of the SPICA coronagraph is the direct observation of Jovian exo-planets. A strategy of the baseline survey and the specifications for the coronagraph instrument for the survey are introduced together. The main wavelengths and the contrast required for the observations are 3.5-27um, and 10^{-6}, respectively.Laboratory experiments were performed with a visible laser to demonstrate the principles of the coronagraphs. In an experiment using binary-shaped pupil coronagraphs, a contrast of 6.7x10^{-8} was achieved, as derived from the linear average in the dark region and the core of the PSF. A coronagraph by a binary-shaped pupil mask is a baseline solution for SPICA because of its feasibility and robustness. On the other hand, a laboratory experiment of the phase induced amplitude apodization/binary-mask hybrid coronagraph has been executed to obtain an option of higher performance, and a contrast of 6.5x10^{-7} was achieved with active wavefront control.Potentially important by-product of the instrument, transit monitoring for characteization of exo-planets, is also described. We also present recent progress of technology on a design of a binary-shaped pupil mask for the actual pupil of SPICA, PSF subtraction, the development of free-standing binary masks, a vacuum chamber, and a cryogenic deformable mirror. Considering SPICA to be an essential platform for coronagraphs and the progress of key technologies, we propose to develop a mid-infrared coronagraph instrument for SPICA and to perform the direct observation of exo-planets with it.Comment: 37th COSPAR Scientific Assembly; Montreal, Canada 13-20 July 2008/Submitted to AS

Therapeutic Value of Lymph Node Dissection Along the Superior Mesenteric Vein and the Posterior Surface of the Pancreatic Head in Gastric Cancer Located in theLower Third of the Stomach

【Background】 Therapeutic value of lymph node dissection along the superior mesenteric vein (14v) and the posterior surface of the pancreatic head (13) remains unclear in gastric cancer patients. 【Methods】 We reviewed 355 patients with advanced gastric cancer in the lower third of the stomach who had undergone gastrectomy at our hospital. 【Results】 The frequency of lymph node (LN) metastasis was 10.2% and 7.4% in stations 13 and 14v, respectively. The frequency of station 13 metastasis was 26.8% for T3/T4 tumors with group 2 LNs metastasis and 1.4% for all other tumors. The frequency of station 14v metastasis was 22.2% for T3/T4 tumors with group 2 LNs metastasis and 1.8% for all other tumors. The therapeutic values for dissecting LN stations 13 and 14v were 1.9 and 0.9, respectively, similar to the therapeutic value for group 2 LN dissection. 【Conclusion】 Because metastasis to stations 13 and 14v occurs frequently in patients with T3/T4 gastric cancer located in the lower third of the stomach who also have metastasis to group 2 LNs, stations 13 and 14v should be dissected in these patients

Postoperative Serum Albumin is a Potential Prognostic Factor for Older Patients with Gastric Cancer

【Background】 The incidence of gastric cancer (GC) among older adults is increasing. Therefore, determining postoperative age-associated prognostic factors is clinically important. This study retrospectively investigated the prognostic significance of serum albumin level in older GC patients. 【Methods】 We enrolled 135 patients aged ? 75 years, who underwent gastrectomies with histopathological diagnoses of gastric adenocarcinoma. 【Results】 Preoperative albumin (pre-Alb) levels in patients with advanced GC and stage III/IV GC were significantly lower than those in patients with early GC (P = 0.0032) and stage I/II GC (P = 0.006), respectively. Postoperative albumin (post-Alb) levels (measured 1 month after surgery) in male patients and in patients with advanced GC were significantly lower than those in female patients (P = 0.024) and those with early GC (P = 0.044), respectively. Post-Alb levels of patients who died of other diseases were significantly lower than those who were still living (P = 0.0004). Prognosis of patients with high post-Alb levels (? 4g/dL) was significantly better than that of patients with low post-Alb levels (< 4g/dL; P = 0.045); and in multivariate analysis, post-Alb level was an independent prognostic indicator. 【Conclusion】 Post-Alb level is a useful predictive factor for the prognosis of older GC patients. Postoperative nutritional support might help improve the prognosis of older GC patients