Climatic cyclicity at Site 806; the GRAPE record

We used the continuous saturated bulk density records collected by the gamma-ray attenuation porosity evaluator (GRAPE) at Ocean Drilling Program Site 806 on the top of the Ontong Java Plateau to evaluate the continuity of the recovered cores and to splice together a complete section from the multiple holes drilled at the site (for the upper 165 m, this is equivalent to approximately 0-5 Ma). The lack of offset in core breaks (between the 9.5-m-long, successive cores) from hole to hole made splicing difficult, and the results are not unambiguous. The composite section was converted to a time series by using biostratigraphy and supplementing this with oxygen-isotope datums for the interval between 2 and 5 Ma. Evolutionary spectra generated from the composite section clearly indicate the presence of Milankovitch frequencies throughout the record. We chose a final age model that was most consistent with a Milankovitch model but have not, as yet, spectrally tuned the data. The GRAPE (saturated bulk density) changes at Site 806 are the result of changes in grain size, with density decreasing as grain size increases. We attribute this to the removal of fine particles by winnowing, leaving a greater percentage of large hollow foraminifers behind— the winnowing effect. This is in contrast to the dissolution effect, which breaks up large hollow foraminifers into fragments but merely transfers intraparticle porosity to interparticle porosity and thus shows significant changes in grain size without significant changes in density. A 300-k.y. piston core record reveals that during this time interval increased winnowing has been associated with glacials and 100-k.y. cyclicity. For the time interval from 5 to 2 Ma, enhanced winnowing continues to be associated with isotopically heavy intervals dominated by 41-k.y. (obliquity) variance. In this band, the winnowing record is highly correlated with the ice-volume record, particularly since the onset of Northern Hemisphere glaciations. Before that time, the grain-size record continues to show variance in the obliquity band whereas the oxygen isotope record shows a shift to the dominance of precessional frequencies. We suggest that the winnowing signal is a response to increased thermohaline circulation and benthic storm activity associated with enhanced north-south thermal gradients during times of climatic degradation

Evolution of Pliocene climate cyclicity at Hole 806B (5-2 Ma); oxygen isotope record

A detailed Pliocene oxygen isotope record from the Ontong Java Plateau, based on measurements of the surface-dwelling planktonic foraminifer Globigerinoides sacculifer, was produced for the period from 5 to 2 Ma. The record documents major long and short-term climate changes. The results show periods of enhanced ice volume at 4.6 to 4.3 Ma and after 2.85 Ma, a long-term warming trend from 4.1 to 3.7 Ma, and a distinct cooling trend that was initiated at 3.5 Ma and progressed through the initiation of large-scale Northern Hemisphere glaciation after 2.85 Ma (according to the time scale of Shackleton and others proposed in 1990). Periods of high average ice volumes also show the highest δ 1 8 amplitudes. The pattern of climate cyclicity changed markedly at about 2.85 Ma. Earlier times were marked by high-frequency variability at the precessional frequencies or even higher frequencies, pointing to low-latitude processes as a main controlling factor driving planktonic δ 1 8 variability in this period. The high-frequency variability is not coherent with insolation and points to strong nonlinearity in the way the climate system responded to orbital forcing before the onset of large scale Northern Hemisphere glaciation. After 3 Ma, stronger 41-k.y. cyclicity appears in the record. The shift in pattern is clearest around 2.85 Ma (according to the time scale proposed by Shackleton and others in 1990), 100-200 k.y. before the most dramatic spread of Northern Hemisphere ice sheets. This indicates that high-latitude processes from this point on began to take over and influence most strongly the δ 1 8 record, which now reflects ice-volume fluctuations related to the climatic effects of obliquity forcing on the seasonality of high-latitude areas, most probably in the Northern Hemisphere. The general Pliocene trend is that high-latitude climate sensitivity and instability was increasing, and the causal factors producing the intensified glacial cyclicity during the Pliocene must be factors that enhance cooling and climate sensitivity in the subarctic areas

Late Cenozoic Micropaleontologic Events in the Equatorial Pacific Sediments

A microbiostratigraphical investigation of five deep-sea sediment cores from the equatorial Pacific was carried out by utilizing planktonic foraminifers, radiolarians and calcareous nannoplankton. Several micropaleontologic events characterized by the first occurrence of taxa were found to provide reliable datum planes for stratigraphic correlation of post-Miocene sediments. These datum planes are : The Buccinosphaera invaginata Datum, Collosphaera tuberosa Datum, Globoquadrina conglomerata Datum, Pulleniatina obliquil-oculata Datum, Gephyrocapsa oceanica Datum, Gephyrocapsa caribbeanica Datum, Anthocyrtidium angulare Datum and Globorotalia (G.) truncatulinoides Datum, in downward sequence. These datum planes are related to the biostratigraphic zonations based on various microfossils, and further to the previously determined paleomagnetic stratigraphy. One new radiolarian species, Amphiropalum praeypsilon, is described

鎖骨下動脈閉塞性動脈硬化症に対する血管内超音波評価を併用したステント留置術の長期治療成績

The objective of this study was to determine long-term outcomes after stent placement for subclavian artery (SA) obstructive lesions assisted by intraoperative intravascular ultrasound (IVUS). The study included 25 lesions in 24 patients who underwent stent placement assisted by intraoperative IVUS for subclavian artery stenosis or obstruction at our hospital between January 2003 and August 2010. Outcome was evaluated based on the results within 30 postoperative days (technical success rate, improvement in upper extremity ischemia, steal syndrome, left-right blood pressure difference, and perioperative complications) and the results after 30 postoperative days (incidence of vertebrobasilar artery territory infarction and restenosis). Stent placement and vessel dilatation were successful in all patients, without perioperative complications. Upper extremity ischemia, steal syndrome, and left-right blood pressure difference disappeared in all cases. During follow-up observation (6-96 months; median 51 months), no restenosis occurred at the stent placement site in any patient. In one case, four years after initial treatment, stenosis was noted proximal to the stent placement site. Satisfactory long-term as well as short-term outcomes were achieved after stent placement for SA obstructive lesions assisted by intraoperative IVUS evaluation.博士（医学）・乙第1362号・平成27年5月28日Copyright © 2014 by SAGE Publications. The definitive version is available at " http://dx.doi.org/10.15274/NRJ-2014-10023

石灰質ナンノ化石からみたパナマ地峡開閉に伴う鮮新世環境変動

金沢大学教養部本年度考察の対象としたのは,国際深海掘削計画(IPOD-ODP)LEG 94,138、165、166の掘削地点606,607,609,610(いずれも北大西洋),844,846,850(いずれも東部赤道太平洋),998と999(カリブ海),1006(バハマ)で得られた下部中新統から鮮新統に至る深海堆積物試料である.試料中の石灰質ナンノ化石を検鏡,同定し,化石群集の時代的変遷を明らかにした.その結果得られた成果は下記の通りである.パナマ地峡両側の太平洋,大西洋海域での石灰質ナンノ化石群集の時代的変遷は,どちらもさまざまな種の消長を繰り返すが,Discoaster tamalis絶滅の層準より上位でカリブ海域とバハマ海域の化石群集に共通点がみられるようになる.このことからパナマ地峡が閉塞したのは2.82Maで,これを境にして大西洋ではメキシコ湾流の発達がみられるようになったと考えられる.一方 北大西洋の更新統中の石灰質ナンノ化石群集を4掘削地点で比較すると,低緯度から高緯度海域に向かって産出種数がわずかながら減少し,群集組成が単調になる傾向がみられる.産出類のいくつかは暖流域,あるいは寒流域に特徴的なものであることが明らかとなった.とくにCoccolithus pelagicusは寒冷種として際だっている.この北大西洋海域で得られた成果をもとに石灰質ナンノ化石種に基づく温度スケールを作成し,このスケールを用いて,パナマ地峡閉塞後の太平洋,大西洋の海峡変化を今後明らかにする.研究課題/領域番号:08454149, 研究期間(年度):1996 – 1997出典：研究課題「石灰質ナンノ化石からみたパナマ地峡開閉に伴う鮮新世環境変動」課題番号08454149（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-08454149/）を加工して作

津軽海峡の開閉時代に関する研究

金沢大学教養部研究課題/領域番号60540502, 研究期間(年度):1985出典：研究課題「津軽海峡の開閉時代に関する研究」課題番号60540502（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-60540502/）を加工して作

Application of susceptibility weighted imaging (SWI) for evaluation of draining veins of arteriovenous malformation: utility of magnitude images.

INTRODUCTION: The current study evaluated the signal characteristics of susceptibility weighted imaging (SWI) of arteriovenous malformation (AVM), especially for draining veins. For this purpose, we identified the draining veins of the AVM on angiography and evaluated the signal on magnitude image for SWI (SWI-mag) and minimum intensity projection image (SWI-minIP). METHODS: Subjects were 14 cases with angiographically proven AVM. SWI-mag, SWI-minIP, and time-of-flight (TOF) magnetic resonance angiography were acquired. For the draining veins of the AVM identified on angiography, we analyzed signal intensity on the images listed above, and classified it into hyperintensity (hyper), mixed intensity (mixed), hypointensity (hypo), and no visualization. RESULTS: On the analysis of 27 angiographically proven draining veins, 19 draining veins were classified as hyper, 3 as mixed, 0 as hypo, and 6 as no visualization on SWI-mag. On TOF images, 21 draining veins were classified as hyper, 2 as mixed, 0 as hypo, and 4 as no visualization, while 6 draining veins did not show hyperintensity on TOF, and SWI-mag visualized 3 of these 6 veins as hyper. CONCLUSION: SWI-mag depicted most draining veins of AVM as hyperintensity. We speculate that this is mainly due to the higher concentration of oxygenated hemoglobin (oxy-Hb) and inflow effect of the draining vein. SWI-mag seems to be useful in the analysis and follow-up for AVM as the signal on the image may reflect physiological status.博士（医学）・乙第1316号・平成25年7月22

T1強調像での信号強度が出生後日数と負の相関性を示す新生児・乳児期の脳構造

Purpose: Although the neonatal and infantile brain typically shows sequential T1 shortening according to gestational age as a result of myelination, several structures do not follow this rule. We evaluated the relationship between the signal intensity of various structures in the neonatal and infantile brain on T1-weighted imaging (T1WI) and either postnatal or gestational age. Materials and Methods: We examined magnetic resonance images from 120 newborns and infants without any abnormalities in the central nervous system. Written informed consent was obtained from all parents and the institutional review board approved the study. Gestational age at examination ranged from 35 weeks, 3 days to 46 weeks, 6 days, and postnatal age ranged from 7 days to 127 days. Signal intensity on T1WI was evaluated on a scale from Grade 1 (indistinguishable from surrounding structures) to Grade 4 (higher than cortex and close to fat). We evaluated relationships between the T1 signal grades of various structures in the neonatal brain and postnatal or gestational age using Spearman’s correlation analysis. Results: Significant positive correlations were identified between T1 signal grade and gestational age in the pyramidal tract (P < 0.001). Conversely, significant negative correlations were evident between T1 signal grade and postnatal age (P < 0.001), in structures including the stria medullaris thalami, fornix cerebellar vermis, dentate nucleus and anterior pituitary gland. Conclusion: Significant negative correlations exist between signal intensity on T1WI and postnatal age in some structures of the neonatal and infantile brain. Some mechanisms other than myelination might play roles in the course of signal appearance.博士（医学）・乙第1405号・平成29年6月28日Copyright © 2017 by Japanese Society for Magnetic Resonance in Medicine : This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives International License(https://creativecommons.org/licenses/by-nc-nd/4.0/deed.ja)