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Planning for the Future Broadband Mobile Satellite Service (MSS)
Trachtman, Eyal,Kawai, Nobuyuki,Kashiki, Kanshiro,Chiba, Eiji 통신위성우주산업연구회 2001 Joint Conference on Satellite Communications Vol.2001 No.-
This paper provides an overview of development plans and activity aiming to deliver Broadband mobile multimedia satellite services globally in the medium and longer terms. The BGAN (Broadband Global Area Network) service, which is mobile satellite service (MSS) to be offered by Inmarsat, is planned to start in 2004 and will utilize the next generation satellite at L-Band. The service will provide the user data rates of up to 432 kb/s. This paper also provides an overview of the Skycast service developed by KDDI, which uses the VSAT with Ku-band to enable broadband and two-way IP transmission. Combining of the MSS and VSAT technologies is finally discussed for a complementary, longer term broadband MSS at higher frequency bands and at higher user data rates.
Tetsuo Sonomura,Nobuyuki Kawai,Kazushi Kishi,Akira Ikoma,Hiroki Sanda,Kouhei Nakata,Hiroki Minamiguchi,Motoki Nakai,Seiki Hosokawa,Hideyuki Tamai,Morio Sato 대한영상의학회 2014 Korean Journal of Radiology Vol.15 No.2
We present a case of a patient with rapid deterioration of esophageal varices caused by portal hypertension accompanied by a large arterioportal shunt that developed after radiofrequency ablation of hepatocellular carcinoma. We used n-butyl cyanoacrylate (NBCA) as an embolic material to achieve pinpoint embolization of the shunt, because the microcatheter tip was 2 cm away from the shunt site. Under hepatic arterial flow control using a balloon catheter, the arterioportal shunt was successfully embolized with NBCA, which caused an improvement in the esophageal varices.
Fuke, Naoki,Sugiyama, Keizo,Kawai, Nobuyuki 통신위성우주산업연구회 2005 Joint Conference on Satellite Communications Vol.2005 No.-
This paper presents characteristics of a satellite system with wideband spreading signals overlaid on conventional FDMA signals within an FSS network using Direct Sequence (DS) technology. This type of application could enable the transmission of additional information using wideband spreading signals within the same transponder. In particular, it could be suitable in the event of natural disasters and similar emergencies for warning and relief operations, because a receiver with a semi omni-directional antenna (e.g. 5dBi) does not require an antenna pointing to the satellite direction, which can be easily changed in such events. Moreover, interference from adjacent satellites is expected to be mitigated by its spreading gain, even if a low-gain antenna is used. We have evaluated the achievable data rate by link budget analysis, which shows that a data rate of several tens of kbit/s is obtainable with an antenna of 5 dBi. Although a relatively low data rate is achieved, due to the limited bandwidth and the C/I criteria, it is still considered to be sufficient to deliver low-rate emergency information.
Fuke, Naoki,Ohseki, Takeo,Iwai, Hisato,Nohara, Mitsuo,Kawai, Nobuyuki 통신위성우주산업연구회 2004 Joint Conference on Satellite Communications Vol.2004 No.-
In this paper, the effect of interference from ultra-wideband (UWB) devices into Fixed Satellite Service (FSS) systems is evaluated. Some examples of the methodologies for the evaluation are also presented. UWB devices are expected to achieve high-speed short-range communication for a number of applications, and technologies for UWB devices are being studied at standardization bodies. In contrast to their benefits, the emissions from UWB devices would cause harmful interference into the existing FSS systems. We evaluate the magnitude of aggregate interference onto the uplink and downlink of the FSS systems. The results of the most studies so far indicate that the interference into the downlink in 4/7GHz band is more critical as compared to the interference into the uplink in 6/8GHz band. These results were sent to the special Task Group at ITU-R which considers technical issues to facilitate the study on the compatibility between UWB devices and rediocommunication services. Furthermore, a new technical approach to explore new satellite services using wideband spreading signals, which operate within frequency bands allocated to the FSS, is introduced. A preliminary analysis shows there will be a possibility to implement an economical service, e.g. broadcast type transmission, by virtue of technology imported from the terrestrial short-range communications.
( Toshiyuki Sato ),( Tetsuya Takagawa ),( Yoichi Kakuta ),( Akihiro Nishio ),( Mikio Kawai ),( Koji Kamikozuru ),( Yoko Yokoyama ),( Yuko Kita ),( Takako Miyazaki ),( Masaki Iimuro ),( Nobuyuki Hida ) 대한장연구학회 2017 Intestinal Research Vol.15 No.3
Background/Aims: Recent genome-wide analyses have provided strong evidence concerning adverse events caused by thiopurine drugs such as azathioprine (AZA) and 6-mercaptopurine. The strong associations identified between NUDT15 p.Arg139Cys and thiopurine-induced leukopenia and severe hair loss have been studied and confirmed over the last 2 years. However, other coding variants, including NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, and FTO p.Ala134Thr, and a noncoding variation in RUNX1 (rs2834826) remain to be examined in detail in this respect. Therefore, we investigated the correlation between these adverse events and the 5 recently identified variants mentioned above among Japanese patients with inflammatory bowel diseases (IBD). Methods: One hundred sixty thiopurine-treated patients with IBD were enrolled. Genotyping was performed using TaqMan SNP Genotyping Assays or Sanger sequencing. Results: None of the 5 variants were associated with gastrointestinal intolerance to AZA. However, NUDT15 p.Arg139Cys was significantly associated with the interval between initiation and discontinuation of AZA among patients with gastrointestinal intolerance. This variant was strongly associated with early (<8 weeks) and late (≥8 weeks) leukopenia and severe hair loss. Moreover, it correlated with the interval between initiation of thiopurine therapy and leukopenia occurrence, and average thiopurine dose. NUDT15 p.Val18_Val19insGlyVal, NUDT15 p.Val18Ile, FTO p.Ala134Thr, and RUNX1 rs2834826 exhibited no significant relationship with the adverse events examined. Conclusions: Of the 5 variants investigated, NUDT15 p.Arg139Cys had the strongest impact on thiopurineinduced leukopenia and severe hair loss; therefore, its genotyping should be prioritized over that of other variants in efforts to predict these adverse events in Japanese patients with IBD. (Intest Res 2017;15:328-337)
Kawada Hiroshi,Goshima Satoshi,Sakurai Kota,Noda Yoshifumi,Kajita Kimihiro,Tanahashi Yukichi,Kawai Nobuyuki,Ishida Narihiro,Shimabukuro Katsuya,Doi Kiyoshi,Matsuo Masayuki 대한영상의학회 2021 Korean Journal of Radiology Vol.22 No.4
Objective: To assess the noncontrast two-dimensional single-shot balanced turbo-field-echo magnetic resonance angiography (b-TFE MRA) features of the abdominal aortic aneurysm (AAA) status following endovascular aneurysm repair (EVAR) and evaluate to detect endoleaks (ELs). Materials and Methods: We examined four aortic stent-grafts in a phantom study to assess the degree of metallic artifacts. We enrolled 46 EVAR-treated patients with AAA and/or common iliac artery aneurysm who underwent both computed tomography angiography (CTA) and b-TFE MRA after EVAR. Vascular measurements on CTA and b-TFE MRA were compared, and signal intensity ratios (SIRs) of the aneurysmal sac were correlated with the size changes in the AAA after EVAR (AAA prognoses). Furthermore, we examined six feasible b-TFE MRA features for the assessment of ELs. Results: There were robust intermodality (r = 0.92–0.99) correlations and interobserver (intraclass correlation coefficient = 0.97–0.99) agreement. No significant differences were noted between SIRs and aneurysm prognoses. Moreover, “mottled high-intensity” and “creeping high-intensity with the low-band rim” were recognized as significant imaging findings suspicious for the presence of ELs (p < 0.001), whereas “no signal black spot” and “layered high-intensity area” were determined as significant for the absence of ELs (p < 0.03). Based on the two positive features, sensitivity, specificity, and accuracy for the detection of ELs were 77.3%, 91.7%, and 84.8%, respectively. Furthermore, the k values (0.40–0.88) displayed moderate-toalmost perfect agreement. Conclusion: Noncontrast MRA could be a promising imaging modality for ascertaining patient follow-up after EVAR.
Hiroshi Kawada,Masayuki Kanematsu,Satoshi Goshima,Hiroshi Kondo,Haruo Watanabe,Yoshifumi Noda,Yukichi Tanahashi,Nobuyuki Kawai,Hiroaki Hoshi 대한영상의학회 2015 Korean Journal of Radiology Vol.16 No.2
To evaluate the multiphase contrast-enhanced magnetic resonance (MR) imaging features of Bacillus Calmette-Guérin (BCG)-induced granulomatous prostatitis (GP). Magnetic resonance images obtained from five patients with histopathologically proven BCGinduced GP were retrospectively analyzed for tumor location, size, signal intensity on T2-weighted images (T2WI) and diffusion-weighted images (DWI), apparent diffusion coefficient (ADC) value, and appearance on gadolinium-enhanced multiphase images. MR imaging findings were compared with histopathological findings. Bacillus Calmette-Guérin-induced GP (size range, 9–40 mm; mean, 21.2 mm) were identified in the peripheral zone in all patients. The T2WI showed lower signal intensity compared with the normal peripheral zone. The DWIs demonstrated high signal intensity and low ADC values (range, 0.44–0.68 x 10-3 mm2/sec; mean, 0.56 x 10-3 mm2/sec), which corresponded to GP. Gadolinium-enhanced multiphase MR imaging performed in five patients showed early and prolonged ring enhancement in all cases of GP. Granulomatous tissues with central caseation necrosis were identified histologically, which corresponded to ring enhancement and a central low intensity area on gadolinium-enhanced MR imaging. The findings on T2WI, DWI, and gadolinium-enhanced images became gradually obscured with time. Bacillus Calmette-Guérin-induced GP demonstrates early and prolonged ring enhancement on gadoliniumenhanced MR imaging which might be a key finding to differentiate it from prostate cancer.
OBSERVATIONAL EVIDENCE FOR AN IMPACT ON THE MAIN-BELT ASTEROID (596) SCHEILA
Ishiguro, Masateru,Hanayama, Hidekazu,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Jun-ichi,Fujiwara, Hideaki,Terada, Hiroshi,Hsieh, Henry H.,Vaubaillon, Jeremie J.,Kawai, Nobuyuki,Yanagisawa, Kenshi,Kuro IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.740 No.1
<P>An unexpected outburst was observed around (596) Scheila in 2010 December. We observed (596) Scheila soon after the impact using ground-based telescopes. We succeeded in the detection of a faint linear tail after 2011 February, which provides a clue to determine the dust ejection date. It is found that the dust particles ranging from 0.1-1 mu m to 100 mu m were ejected into the interplanetary space impulsively on December 3.5 +/- 1.0 day. The ejecta mass was estimated to be (1.5-4.9) x 10(8) kg, suggesting that an equivalent mass of a 500-800 m diameter crater was excavated by the event. We also found that the shape of the light curve changed after the impact event probably because fresh material was excavated around the impact site. We conclude that a decameter-sized asteroid collided with (596) Scheila only eight days before the discovery.</P>
INTERPRETATION OF (596) SCHEILA'S TRIPLE DUST TAILS
Ishiguro, Masateru,Hanayama, Hidekazu,Hasegawa, Sunao,Sarugaku, Yuki,Watanabe, Jun-ichi,Fujiwara, Hideaki,Terada, Hiroshi,Hsieh, Henry H.,Vaubaillon, Jeremie J.,Kawai, Nobuyuki,Yanagisawa, Kenshi,Kuro IOP Publishing 2011 ASTROPHYSICAL JOURNAL LETTERS - Vol.741 No.1
<P>Strange-looking dust cloud around asteroid (596) Scheila was discovered on 2010 December 11.44-11.47. Unlike normal cometary tails, it consisted of three tails and faded within two months. We constructed a model to reproduce the morphology of the dust cloud based on the laboratory measurement of high-velocity impacts and the dust dynamics. As a result, we succeeded in reproducing the peculiar dust cloud by an impact-driven ejecta plume consisting of an impact cone and downrange plume. Assuming an impact angle of 45 degrees, our model suggests that a decameter-sized asteroid collided with (596) Scheila from the direction of (alpha(im), delta(im)) = (60 degrees, -40 degrees) in J2000 coordinates on 2010 December 3. The maximum ejection velocity of the dust particles exceeded 100 m s(-1). Our results suggest that the surface of (596) Scheila consists of materials with low tensile strength.</P>