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Search Results: 1 - 10 of 3533 matches for " Yutaka Yamada "
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Heating of Intracluster Gas by Jet Activities of AGN: Is the "Preheating" Scenario Realistic?
Masako Yamada,Yutaka Fujita
Physics , 2001, DOI: 10.1086/320674
Abstract: We investigate the non-gravitational heating of hot gas in clusters of galaxies (intracluster medium; ICM) on the assumption that the gas is heated well before cluster formation ('preheating'). We examine the jet activities of radio galaxies as the sources of excess energy in ICM, and the deformation of the cosmic microwave background (the Sunyaev-Zel'dovich effect) by hot electrons produced at the jet terminal shocks. We show that the observed excess entropy of ICM and {\sl COBE/FIRAS} upper limit for the Compton $y$-parameter are compatible with each other only when the heating by the jets occurred at relatively small redshift ($z\lesssim 3$). Since this result contradicts the assumption of 'preheating', it suggests that the heating occurred simultaneously with or after cluster formation.
Melting and Solidification Heat Transfer Characteristics of a Phase-Change Material in a Latent Heat Storage Vessel: Effects of a Perforated Partition Plate and Metal Fiber  [PDF]
Than Tun Naing, Akihiko Horibe, Naoto Haruki, Yutaka Yamada
Journal of Power and Energy Engineering (JPEE) , 2017, DOI: 10.4236/jpee.2017.58002
Abstract: Today, latent heat storage technology has advanced to allow reuse of waste heat in the middle-temperature range. This paper describes an approach to develop a latent heat storage system using middle-temperature waste heat (~100oC - 200oC) from factories. Direct contact melting and solidification behavior between a heat-transfer fluid (oil) and a latent heat storage material mixture were observed. The mixture consisted of mannitol and erythritol (Cm = 70 mass %, Ce = 30 mass %) as a phase-change material (PCM). The weight of the PCM was 3.0 kg and the flow rate of the oil, foil, was 1.0, 1.5, or 2.0 kg/min. To decrease the solidified height of the PCM mixture during the solidification process, a perforated partition plate was installed in the PCM region in the heat storage vessel. PCM coated oil droplets were broken by the perforated partition plate, preventing the solidified height of the PCM from increasing. The solidification and melting processes were repeated using metal fiber. It was found that installing the metal fiber was more effective than installing the perforated partition plate to prevent the flow out problem of the PCM.
Corrosion in Tap Water and Hot Water Supply Facilities of Stainless Steel Type 304 Pipes  [PDF]
Noriyuki Tanaka, Shigeru Sato, Ippei Watanabe, Yutaka Yamada, Osamu Sakurada
Materials Sciences and Applications (MSA) , 2018, DOI: 10.4236/msa.2018.91005
Abstract: We performed corrosion case study and corrosion tests to assess the corrosion resistance of stainless steel type 304 pipes in tap water and hot water facilities. Circulating test equipment used for corrosion tests and two types of sample, plates and straight pipe specimens, were examined under different conditions of residual chlorine concentration in the test water. The results of case study analysis indicated that high degrees of pitting corrosion occurred on straight pipes with inner diameter < 50 mm. The results of corrosion tests showed that the residual chlorine concentration around the pitting corrosion of stainless steel type 304 was greater than 0.3 mg/L in the plate, regardless of the remaining chlorine concentration in the straight pipe specimens. These results suggest that straight pipes have higher corrosion susceptibility because of bending during production.
Cecal volvulus associated with mobile cecum in Cornelia de Lange syndrome: Report of a case  [PDF]
Masataka Takahashi, Toshihiko Watanabe, Hideaki Tanaka, Waka Yamada, Koji Yamada, Yasushi Fuchimoto, Shunsuke Nosaka, Yutaka Kanamori
Open Journal of Pediatrics (OJPed) , 2013, DOI: 10.4236/ojped.2013.32018
Abstract: We report a case of cecal volvulus in an 11-year-old girl who had been diagnosed with Cornelia de Lange syndrome. She had undergone operative fundoplication several years earlier and was referred to our institute for treatment of intestinal obstruction. A severely dilated colon was detected on abdominal roentgenogram, and abdominal CT and colonic enema strongly suggested cecal volvulus. Emergency operation was performed and cecal volvulus with mobile cecum was ascertained; the volvulus was corrected and the mobile cecum was fixed to the peritoneum on the right side. Neurologically handicapped patients sometimes suffer from cecal volvulus, and patients with Cornelia de Lange syndrome are at especially high risk. Moreover, operative fundoplication promotes intestinal dilatation and it may be another risk factor for cecal volvulus.
Congenital median raphe cysts: Coexistence of cystic lesions and canal-like lesions  [PDF]
Masataka Takahashi, Toshihiko Watanabe, Kaori Sato, Michinobu Ohno, Koji Yamada, Toshiko Takezoe, Yasushi Fuchimoto, Hajime Ohkita, Kentaro Matsuoka, Yutaka Kanamori
Open Journal of Pediatrics (OJPed) , 2013, DOI: 10.4236/ojped.2013.33048

Median raphe cyst of the perineum is a rare congenital anomaly and was first reported in 1895. We report a 9-year-old male with median raphe cysts in the perineum which had become swollen and then spontaneously ruptured several times since he was 3 years old. There were two separate lesions; one was a cystic lesion and the other was a canal-like lesion. They were completely excised and the inner layer of the cysts was composed of transitional epithelium.

Extraskeletal Osteosarcoma of the Thigh: An Autopsy Case Report
Akihito Nagano,Takatoshi Ohno,Yutaka Nishimoto,Kazunari Yamada,Katsuji Shimizu
Sarcoma , 2009, DOI: 10.1155/2009/186565
Abstract: We report a case of extraskeletal osteosarcoma (ESOS) and autopsy findings. A 35-year-old man presented with an ossified tumor in the right thigh and lung metastasis. The lung tumors continued to develop despite multiagent chemotherapy and caused death within 8 months. Autopsy revealed many secondary lesions in the lungs, especially in the left lung. Histopathologically, the primary tumor and one of the secondary tumors showed proliferation of spindle-shaped tumor cells focally forming lace-like osteoid material. Therefore, we made a definite diagnosis of ESOS.
The New Model of Chemical Evolution of r-process Elements Based on The Hierarchical Galaxy Formation I: Ba and Eu
Yutaka Komiya,Shimako Yamada,Takuma Suda,Masayuki Y. Fujimoto
Physics , 2014, DOI: 10.1088/0004-637X/783/2/132
Abstract: We investigate the chemical enrichment of r-process elements in the early evolutionary stages of the Milky Way halo within the framework of hierarchical galaxy formation using a semi-analytic merger tree. In this paper, we focus on heavy r-process elements, Ba and Eu, of extremely metal-poor (EMP) stars and give constraints on their astronomical sites. Our models take into account changes of the surface abundances of EMP stars by the accretion of interstellar matter (ISM). We also consider metal-enrichment of intergalactic medium (IGM) by galactic winds and the resultant pre-enrichment of proto-galaxies. The trend and scatter of the observed r-process abundances are well reproduced by our hierarchical model with $\sim 10\%$ of core-collapse supernovae in low-mass end ($\sim 10M_{\odot}$) as a dominant r-process source and the star formation efficiency of $\sim 10^{-10} \hbox{yr}^{-1}$. For neutron star mergers as an r-process source, their coalescence timescale has to be $ \sim 10^7$yrs, and the event rates $\sim 100$ times larger than currently observed in the Galaxy. We find that the accretion of ISM is a dominant source of r-process elements for stars with [Ba/H] < -3.5. In this model, a majority of stars at [Fe/H] < -3 are formed without r-process elements but their surfaces are polluted by the ISM accretion. The pre-enrichment affects $\sim 4\%$ of proto-galaxies, and yet, is surpassed by the ISM accretion in the surface of EMP stars.
The Stellar Abundances for Galactic Archaeology (SAGA) Database II - Implications for Mixing and Nucleosynthesis in Extremely Metal-Poor Stars and Chemical Enrichment of the Galaxy
Takuma Suda,Shimako Yamada,Yutaka Katsuta,Yutaka Komiya,Chikako Ishizuka,Wako Aoki,Masayuki Y. Fujimoto
Physics , 2010, DOI: 10.1111/j.1365-2966.2011.17943.x
Abstract: We discuss the characteristics of known extremely metal-poor (EMP) stars in the Galaxy using the Stellar Abundances for Galactic Archaeology (SAGA) database (Suda et al. 2008, PASJ, 60, 1159).The analyses of carbon-enhanced stars in our sample suggest that the nucleosynthesis in AGB stars can contribute to the carbon enrichment in a different way depending on whether the metallicity is above or below [Fe/H] ~ -2.5, which is consistent with the current models of stellar evolution at low metallicity. We find the transition of the initial mass function at [Fe/H] ~ -2 in the viewpoint of the distribution of carbon abundance and the frequency of carbon-enhanced stars. For observed EMP stars, we confirmed that some, not all, of observed stars might have undergone at least two types of extra mixing to change their surface abundances. One is to deplete the lithium abundance during the early phase of red giant branch. Another is to decrease the C/N ratio by one order of magnitude during the red giant branch phase. Observed small scatters of abundances for alpha-elements and iron-group elements suggest that the chemical enrichment of our Galaxy takes place in a well-mixed interstellar medium. We find that the abundance trends of alpha-elements are highly correlated with each other, while the abundances of iron-group elements are subject to different slopes relative to the iron abundance. This implies that the supernova yields of alpha-elements are almost independent of mass and metallicity, while those of iron-group elements have a metallicity dependence or mass dependence with the variable initial mass function.The occurrence of the hot bottom burning in the mass range of 5 <~ M / Msun <~ 6 is consistent with the initial mass function of the Galaxy peaked at ~ 10 - 12 Msun to be compatible with the statistics of carbon enhanced stars with and without s-process element (truncated)
Non-Hodgkin’s lymphoma: A case of testis lymphoma metastasized to the gallbladder  [PDF]
Yutaka Tsutsumi, Reiki Ogasawara, Fumiyasu Yamamoto, Yutaka Yamada, Yasuyuki Komatsu, Kazuhiko Ichiki, Shinich Ito, Nobuaki Kurauchi, Kazuhiro Kudo, Norihiko Shimoyama, Junji Tanaka, Masahiro Asaka, Masahiro Imamura, Hirohito Naruse, Nobuo Masauzi
Open Journal of Internal Medicine (OJIM) , 2012, DOI: 10.4236/ojim.2012.21003
Abstract: Testis lymphoma (diffuse large B cell lymphoma) metastasized to the gallbladder. The gall bladder is rarely involved in cases of the malignant lymphoma, and lymphoma metastasis from the testis to the gallbladder has not been previously reported. These reports may possibly change by the introduction of PET/CT. Furthermore, although it was a struggle to diagnose this particular case, there is a possibility that we may have been able to recognize metastasis from the testis at an earlier stage if PET/CT had been conducted.
Is the Tokyo Foreign Exchange Market Efficient from Two Perspectives of Forward Bias and Anomaly?  [PDF]
Yutaka Kurihara
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.24067
Abstract: This paper examines the efficiency of the Tokyo Foreign Exchange Market from two perspectives. One is whether or not forward bias in this market has existed and the other is the effect of interventions in the market with a focus on whether or not a day-of-the-week anomaly exists in it. Empirical results show that forward exchange rates are a biased predictor of future spot exchange rates; however, there are some anomalies in the market. The findings suggest the conclusion that this market has not been completely efficient.
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