359 research outputs found

    Regional cingulum disruption, not gray matter atrophy, detects cognitive changes in amnestic mild cognitive impairment subtypes

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    Amnestic mild cognitive impairment (aMCI), which has a high risk of progression to Alzheimer's disease (AD), can be classified into single domain (S-aMCI) and multiple domain (M-aMCI) subtypes. We investigated the integrity of regional gray matter and segments of the cingulum bundle with diffusion spectrum imaging tract-specific analysis, and their relationships to neuropsychological functioning, in 46 individuals with aMCI (S-aMCI n = 24; M-aMCI n = 22) and 36 healthy controls (HC). Results demonstrated that although both aMCI groups were impaired on all memory measures relative to HCs, the M-aMCI group demonstrated worse performance on paired association memory and on selective executive function relative to the S-aMCI group. The two aMCI groups did not show significant atrophy in regional gray matter indices as compared to the HC group, but the M-aMCI group showed significant disruption in white matter of the left anterior and inferior cingulum bundles relative to the S-aMCI and HC groups. Furthermore, disruption in the inferior cingulum bundles was significantly associated with executive function and attention/processing speed in all aMCI participants above and beyond the contribution of bilateral hippocampal volumes. Overall, these results indicate that the degeneration of cingulum fibers did not appear to arise from degeneration of the corresponding cerebral cortex. It also suggests relatively greater sensitivity of a white matter biomarker and comprehensive neuropsychological evaluation over gray matter biomarkers in early detection of AD

    Convex functions on Grassmannian manifolds and Lawson–Osserman problem

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    AbstractWe derive estimates of the Hessian of two smooth functions defined on Grassmannian manifold. Based on it, we can derive curvature estimates for minimal submanifolds in Euclidean space via Gauss map as in [Y.L. Xin, Ling Yang, Curvature estimates for minimal submanifolds of higher codimension, arXiv: 0709.3686; 24]. In this way, the result for Bernstein type theorem done by Jost and the first author could be improved

    (30(1):15-20)Development of mat rush varieties Tainung selection No.1 and No.2

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    藺草新品系FS-73-I-8031及FS-72-P-8006,係於民國62與61年分別由日本引進,歷經品種觀察、品種比較、綜合栽培技術示範及新品系示範等試驗,成績優異,公頃平均最高產量各比對照種岡山3號分別增產28.9與56.2%。分級草量,一級草佔總草量之比率,平均最高各達17.9%與13.68%,均比岡山3號高,尖枯長度兩新品種亦較短。由於其農藝性狀表現優異及高產量,經提請命名審查獲正式命名為臺農選1號及2號。Two lines mat rush, Fs-73-I-8031 and Fs-72-P-8006, were introduced from Japan in 1973 and 1972, respectively, and were cultured acclimatized and selected TARI and other regions. The performance of the two lines has been outstanding in comparative trials, integrated cultural demonstration and the new-line demomstration. The straw yields per hectare of the two lines were 28.9% and 56.2%, respectively, higher than that of Kan-an No.3, served as the check variety, The ratios of first-grade grass to total straw yield of the two lines were 17.9% and 13.7%, respectively, higher than that of the check variety. Both the two lines also showed a shorter tip-rot than the check variety. On account of the high yielding and the superior agronomic performance, the two lines were registered as Tainung selections No.1 and No.2, respectively, in 1980
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