检索结果-南通市图书馆

The role of water in Earth's mantle

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

National Science Review 2020年第1期7卷 224-232页

作者： Eiji ohtani Graduate School of Science Tohoku University

Geophysical observations suggest that the transition zone is wet locally. Continental and oceanic sediment components together with the basaltic and peridotitic components might be transported and accumulated in the transition zone. Low-velocity anomalies at the upper mantle–transition zone boundary might be caused by the existence of dense hydrous magmas. Water can be carried farther into the lower mantle by the slabs. The anomalous Q and shear wave regions locating at the uppermost part of the lower mantle could be caused by the existence of fluid or wet magmas in this region because of the water-solubility contrast between the minerals in the transition zone and those in the lower mantle. δ-H solid solution AlO2H–MgSiO4H2carries water into the lower mantle. Hydrogen-bond symmetrization exists in high-pressure hydrous phases and thus they are stable at the high pressures of the lower mantle. Thus, theδ-H solid solution in subducting slabs carries water farther into the bottom of the lower mantle. Pyrite FeO2Hxis formed due to a reaction between the core and hydrated slabs. This phase could be a candidate for the anomalous regions at the core–mantle boundary.

关键词： water hydrous phase subducting slab transition zone lower mantle hydrogen-bond symmetrization core–mantle boundary

Conjecture with water and rheological control for subducting slab in the mantle transition zone

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Geoscience Frontiers 2015年第1期6卷 79-93页

作者： Fumiko Tajima Masaki Yoshida Eiji ohtani University of California at Irvine 4164 Frederick Reines Hall4IrvineCA 92697USA Institute for Research on Earth Evolution(IFREE) Japan Agency for Marine-Earth Science and Technology(JAMSTEC) Department of Earth and Materials Science Graduate School of ScienceTohoku University

Seismic observations have shown structural variation near the base of the mantle transition zone （MTZ） where subducted cold slabs, as visualized with high seismic speed anomalies （HSSAs）, flatten to form stagnant slabs or sink further into the lower mantle. The different slab behaviors were also accompanied by variation of the ＂660 kin＂ discontinuity depths and low viscosity layers （LVLs） beneath the MTZ that are suggested by geoid inversion studies. We address that deep water transport by subducted slabs and dehydration from hydrous slabs could affect the physical properties of mantle minerals and govern slab dynamics. A systematic series of three-dimensional numerical simulation has been conducted to examine the effects of viscosity reduction or contrast between slab materials on slab behaviors near the base of the MTZ. We found that the viscosity reduction of subducted crustal material leads to a sepa- ration of crustal material from the slab main body and its transient stagnation in the MTZ. The once trapped crustal materials in the MTZ eventually sink into the lower mantle within 20 30 My from the start of the plate subduction. The results suggest crustal material recycle in the whole mantle that is consistent with evidence from mantle geochemistry as opposed to a two-layer mantle convection model. Because of the smaller capacity of water content in lower mantle minerals than in MTZ minerals, dehydration should occur at the phase transformation depth, ~660 kin. The variation of the disconti- nuity depths and highly localized low seismic speed anomaly （LSSA） zones observed from seismic P waveforms in a relatively high frequency band （~ 1 Hz） support the hypothesis of dehydration from hydrous slabs at the phase boundary. The LSSAs which correspond to dehydration induced fluids are likely to be very local, given very small hydrogen （H＋） diffusivity associated with subducted slabs. The image of such local LSSA zones embedded in HSSAs may not be necessarily captured

关键词： Stagnant slab Discontinuity depth variation Deep water transport by subduction Crustal separation Crustal recycling

维普期刊数据库

MULTIPLE ELECTRON CAPTURE PROCESSES BY HIGHLY CHARGED IONS FROM ATOMS

在线全文

学校读者我要写书评

暂无评论

原子与分子物理学报 1991年第1期8卷 1713-1715页

作者： Shunsuke ohtani Chofu-si Institute for Laser Science The University of Electro-Communications Chofugaoka 1-5-1 Tokyo 182 Japan

Recent observations for multiple electron transfer processes inslow highly charged ion-atom collisions are presented,by usingthe ejected electron spectroscopy and the translational energygain spectroscopy.

关键词： In MULTIPLE ELECTRON CAPTURE PROCESSES BY HIGHLY CHARGED IONS FROM ATOMS

Efficacy and safety of emergency endoscopic retrograde cholangiopancreatography for acute cholangitis in the elderly

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2016年第37期22卷 8382-8388页

作者： Gen Tohda Masahiro ohtani Masaki Dochin Department of Gastroenterology Fukui Kosei Hospital Fukui Fukui 918-8537 Japan Second Department of Internal Medicine Faculty of Medical SciencesUniversity of Fukui Eiheji-cho Fukui 910-1193 Japan

AIM To investigate the efficacy and safety of emergency endoscopic retrograde cholangiopancreatography(ERCP) in elderly patients with acute cholangitis. METHODS From June 2008 to May 2016, emergency ERCPs were performed in 207 cases of acute cholangitis at our institution. Patients were classified as elderly if they were aged 80 years and older(n = 102); controls were under the age of 80 years(n = 105). The patients' medical records were retrospectively reviewed for comorbidities, laboratory data, etiology of cholangitis(presence of biliary stones, biliary stricture and malignancy), details of the ERCP(therapeutic approaches, technical success rates, procedure duration), ERCP-related complications and mortality. RESULTS The frequency of comorbidities was higher in the elderly group than the control group(91.2% vs 67.6%). Periampullary diverticulum was observed in the elderly group at a higher frequency than the control group(24.5% vs 13.3%). Between the groups, there was no significant difference in the technical success rates(95.1% vs 95.2%) or endoscopicprocedure durations. With regard to the frequency of ERCP-related complications, there was no significant difference between the two groups(6.9% vs 6.7%), except for a lower rate of post-ERCP pancreatitis in the elderly group than in the control group(1.0% vs 3.8%). Neither angiographic nor surgical intervention was required in any of the cases with ERCP-related complications. There was no mortality during the observational periods. CONCLUSION Emergency ERCP for acute cholangitis can be performed safely even in elderly patients aged 80 years and older.

关键词： Acute cholangitis Endoscopic retrograde cholangiopancreatography Complication Comorbidity Elderly

Influence of comorbidity on outcomes of older patients with acute pancreatitis based on a national administrative database

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2015年第4期14卷 422-428页

作者： Atsuhiko Murata Makoto ohtani Keiji Muramatsu Shinya Matsuda Department of Preventive Medicine and Community Health School of Medicine University of Occupational and Environmental Health

Little information is available on the influ- ence of comorbidities on outcomes of older patients with acute pancreatitis. This study aimed to investigate the influence of co- morbidities on outcomes of older patients with acute pancreati- tis using data from a national Iapanese administrative database. METHODS： A total of 14 322 older patients （〉70 years） with acute pancreatitis were referred to 1090 hospitals between 2010 and 2012 in Japan. We collected patients＇ data from the administrative database to compare the in-hospital mortal- ity and length of stay of older patients with acute pancreatitis. The patients were categorized into four groups according to comorbidity level using the Charlson Comorbidity Index （CCI）： none （CCI score=0; n=6890）; mild （1; n=3874）; moder- ate （2; n=2192） and severe （〉3; n=1366）. RESULTS： Multiple logistic and linear regression analyses revealed that severe comorbidity was significantly associated with higher in-hospital mortality and longer length of stay [odds ratio （OR）=2.26; 95% confidence interval （CI）： 1.75-2.92, P〈0.001 and coefficient 4.37 days; 95% CI： 2.89-5.85, P〈0.001, respectively]. In addition, cardiovascular and renal diseases were the most significant comorbidities affecting outcomes of the older patients. ORs of cardiovascular and renal diseases for mortality were 1.44 （95% CI： 1.13-1.85, P=0.003） and 2.69 （95% CI： 1.88-3.85, P〈0.001）, respectively, and coefficients forlength of stay were 3.01 days （95% CI： 1.34-4.67, P〈0.001） and 3.72 days （95% CI： 1.01-6.42, P=0.007）, respectively. CONCLUSION： This study demonstrated that comorbidities significantly influenced outcomes of older patients with acute pancreatitis and cardiovascular and renal comorbidities were significant factors affecting outcomes.

关键词： acute pancreatitis comorbidity length of stay databases

维普期刊数据库

Meta-analysis of short-term outcomes after laparoscopy-assisted distal gastrectomy

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2006年第47期12卷 7676-7683页

作者： Shunsuke Hosono Yuichi Arimoto Hiroshi ohtani Yoshitetsu Kanamiya Department of Surgery Osaka City Sumiyoshi Hospital 1-2-16 Higashi-Kagaya Suminoe-ku Osaka 559-0012 Japan

AIM： To elucidate the current status of laparoscopyassisted distal gastrectomy （LADG） with regard to its short-term outcomes by comparing it with conventional open distal gastrectomy （CODG）.METHODS： Original articles published from 3anuary 1991 to August 2006 were searched in the MEDLINE, EMBASE, and Cochrane Controlled Trials Register. Clinical appraisal and data extraction were conducted independently by 2 reviewers. A meta-analysis was performed using a random effects model.RESULTS： Outcomes of 1611 procedures from 4 randomized controlled trials and 12 retrospective studies were analyzed. Compared to CODG, LADG was a longer procedure （weighted mean difference [WMD] 54.3; 95% confidence interval [CI] 38.8 to 69.8; P 〈 0.001）, but was associated with a lower associated morbidity （odds ratio [OR] 0.54; 95% CI 0.37 to 0.77; P 〈 0.001）; this was most significant for postoperative ileus （OR 0.27; 95% CI 0.09 to 0.84; P = 0.02）. There was no significant difference between the two groups in anastomotic, pulmonary, and wound complications and mortality. Duration from surgery to first passage of flatus was faster （WMD -0.68; 95% CI -0.85 to -0.50; P 〈 0.001） and the frequency of additional analgesic requirement （WMD -1.36; 95% CI -2.44 to -0.28; P = 0.01）, and duration of hospital stay （WMD -5.51; 95% CI -7.61 to -3,42; P 〈 0,001） were significantly lower after LADG, However, a significantly higher number of lymph nodes were dissected by CODG （WMD -4.35; 95% CI -5.73 to -2.98; P 〈 0.001）. CONCLUSION： LADG for early gastric cancer is associated with a lower morbidity, less pain, faster bowel function recovery, and shorter hospital stay.

关键词： Laparoscopic gastrectomy Gastric cancer Postoperative complications Mortality Lymphadenectomy Meta-analysis

Formation of Non-Maxwellian Distribution and Its Role in Collisionless Driven Reconnection

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Communications in Computational Physics 2008年第8期4卷 496-505页

作者： R.Horiuchi H.ohtani National Institute for Fusion Science Toki 509-52Japan The Graduate University for Advanced Studies Toki 509-52Japan

The dynamical evolution of collisionless driven reconnection is investigated by using an electromagnetic particle simulation code in a microscopic open *** in-plane electrostatic field is excited in the central region of current sheet under the influence of an external driving *** a result of the amplification of unmagnetized meandering motion by the electrostatic field particle distribution function is modified from the shifted Maxwellian to an anisotropic one in the current *** ion hole appears at the center of current sheet in the phase space,where distribution becomes two-peaked and no ions exist in low velocity region between two *** strongmodification of distribution function leads to the generation of off-diagonal components of pressure tensor term,which is one of major causes to violate frozen-in constraint and trigger collisionless reconnection.

关键词： Collisionless reconnection particle simulation open system multi-scale physics

EVOLUTION OF CREEP-FATIGUE DAMAGE IN TYPE 304STAINLESS STEEL AND ITS DETECTION BY ELECTRICALPOTENTIAL METHOD

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 1998年第6期11卷 463-469页

作者： N.Tada T.Kitamura R.ohtani E.Nakayama Kyoto Univ Kyoto Japan

Creep-fatigue test was carried out using smooth round bar specimens of Type 304 stainless steel. Cavities and small cracks on the cross-section of the specimen were carefully observed by a scanning laser microscope. Moreover, direct current electrical potential method (DC-EPM) was applied in order to evaluate non-destructively the distribution of internal cracks. The distribution evaluated by DC-EPM agrees well with the actual one. (Edited author abstract) 9 Refs.

关键词： creep-fatigue cavity small crack Type 304 stainless steel electrical potential method

维普期刊数据库

IMMERSIVE VR VISUALIZATIONS BY VFIVE: PART 2: APPLICATIONS

在线全文

学校读者我要写书评

暂无评论

International Journal of Modeling, Simulation, and Scientific Computing 2013年第S01期4卷 54-69页

作者： AKIRA KAGEYAMA NOBUAKI OHNO SHINTARO KAWAHARA KAZUO KASHIYAMA HIROAKI ohtani Graduate School of System Informatics Kobe University Kobe 657-8501Japan Graduate School of Simulation Studies University of Hyogo Kobe 650-0047Japan Earth Simulator Center Japan Agency for Marine-Earth Science and Technology Yokohama 236-0001 Japan Department of Civil and Environmental Engineering Chuo University Bunkyo-ku 112-8551Japan National Institute for Fusion Science Toki 509-5292 Japan The Graduate University for Advanced Studies(SOKENDAI)Toki 509-5292Japan

VFIVE is a scientific visualization application for CAVE-type immersive virtual reality(VR)*** source codes are freely *** is used as a research tool in various VR *** also lays the groundwork for developments of new visualization software for *** this paper,we pick up five CAVE systems in four different institutions in *** of VFIVE in each CAVE system are *** emphases will be placed on scientific and technical achievements made possible by VFIVE.

关键词： Virtual reality CAVE system immersive display system.