79 research outputs found

    Sodium temperature lidar based on injection seeded Nd:YAG pulse lasers using a sum-frequency generation technique

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    We report on a sodium (Na) temperature lidar based on two injection seeded Nd:YAG pulse lasers using single-pass sum-frequency generation. The laser power at 589 nm is 400 mW (40 mJ per pulse at a repetition rate of 10 Hz) and the pulse width is 22 nsec FWHM. The narrowband laser tuned to the Doppler broadened Na D(2) spectrum enables us to measure the temperature of the mesopause region (80-115 km). This solid-state transportable system demonstrated high performance and capability at Syowa Station in Antarctica for 3 years and at Uji in Japan for an additional year without any major operational troubles. (C) 2011 Optical Society of AmericaArticleOPTICS EXPRESS. 19(4):3553-3561 (2011)journal articl

    Sodium temperature lidar observation at Syowa Station: Summary of three-year observations and unusually high temperature in 2002

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    Total 223 nights (2002 hours) of temperature measurement in the mesopause region (80-105 km) was successfully done in wintertime at Syowa Station (69ºS, 39ºE) starting from 2000 through 2002. Monthly mean temperatures were calculated using nightly mean temperatures and year-to-year variation was examined. The monthly temperature of 2002 shows unusually higher (25 K and 20 K) in June and July compared with previous 2 years. Variations of individual nights showed the temperatures at 80 km, 85 km and 110 km are in good agreement among three years through the observation period. The temperature of 2002 began to increase from the middle of May and was back to normal around the end of July in the limited altitude range of 90-105 km

    First mesopause temperature measurements using sodium lidar observations in the Antarctic region

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    The mesopause temperature structure was observed using a sodium temperature lidar system at Syowa Station (69°00\u27 S, 39°35\u27 E), beginning in February 2000. The laser transmitter was newly developed and included two injection-seeded Nd: YAG lasers. Regular observations were performed using the two-frequency technique as demonstrated by C.Y. She et al. (Geophys. Res. Lett., 17, 929, 1990), with a spatial resolution of about 1 km and a temporal resolution of 6 min. The temperature structures of the 85km to 105km region of the upper atmosphere were measured by Na D_2 Doppler profile-fitting as well as the two-frequency technique. Temperatures derived from the two techniques agreed well and were consistent with the MSIS 90 model temperature structure. Night-time temperature variations over a 15-hour period were measured in May 2000. A large temperature fluctuation with an interval of about 4 hours, and an amplitude of 60 K (probably caused by gravity waves) was observed. From the average night temperature profile, the mesopause was determined to be located at 102km, and have a temperature of 180K. These values are similar to winter values observed in the northern hemisphere

    Composite Bonded Magnets With Self-Recoverability <newline/>for Miniaturized Anisotropic Magnet Rotor

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    In the preparation of a miniaturized rotor, a composite bonded magnet was fabricated by taking advantage of self-recoverability. A preformed magnet was synthesized by using incomplete three-dimensional network molecular structure which was formed under the optimum conditions at a temperature of 433 K, an alignment field of 1.4 MA/m, and a low compacting pressure of 50 MPa, respectively. The preformed ones were extruded and compressed into a ring-shaped magnet by using the self-recoverability at a pressure of 200 MPa and a temperature of 423 K under non-alignment-field. Through the process, a composite bonded magnet rotor in the shape of a ring could be prepared without a bonding layer. It was clarified that a 4 pole/6 slot DC brush less motor can be obtained by using the ring-shaped rotor comprising a parallel oriented anisotropic magnet with 7 mm in outer diameter, 158 kJ/m3 in (BH)max, and 6.2 Mg/m3 in density, respectively. Resultantly, the developed rotor enabled us to increase the S-T gradient by 1.75 times compared with that for a conventional isotropic Nd-Fe-B bonded magnet rotor with the same dimensions

    Essential role of gastric gland mucin in preventing gastric cancer in mice

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    信州大学博士(医学)・学位論文・平成24年3月31日授与(甲第916号)・唐澤文寿Gastric gland mucin secreted from the lower portion of the gastric mucosa contains unique O-linked oligosaccharides (O-glycans) having terminal alpha 1,4-linked N-acetylglucosamine residues (alpha GlcNAc). Previously, we identified human alpha 1,4-N-acetylglucosaminyltransferase (alpha 4GnT), which is responsible for the O-glycan biosynthesis and characterized alpha GlcNAc function in suppressing Helicobacter pylori in vitro. In the present study, we engineered A4gnt(-/-) mice to better understand its role in vivo. A4gnt(-/-) mice showed complete lack of alpha GlcNAc expression in gastric gland mucin. Surprisingly, all the mutant mice developed gastric adenocarcinoma through a hyperplasia-dysplasia-carcinoma sequence in the absence of H. pylori infection. Microarray and quantitative RT-PCR analysis revealed upregulation of genes encoding inflammatory chemokine ligands, proinflammatory cytokines, and growth factors, such as Ccl2, Il-11, and Hgf in the gastric mucosa of A4gnt(-/-) mice. Further supporting an important role for this O-glycan in cancer progression, we also observed significantly reduced alpha GlcNAc in human gastric adenocarcinoma and adenoma. Our results demonstrate that the absence of alpha GlcNAc triggers gastric tumorigenesis through inflammation-associated pathways in vivo. Thus, alpha GlcNAc-terminated gastric mucin plays dual roles in preventing gastric cancer by inhibiting H. pylori infection and also suppressing tumor-promoting inflammation.ArticleJOURNAL OF CLINICAL INVESTIGATION. 122(3):923-934 (2012)journal articl
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