436 research outputs found
Desingularization of matrix equations employing hypersingular integrals in boundary element methods using double nodes
In boundary element methods, the method of using double nodes at corners is a
useful approach to uniquely define the normal direction of boundary elements.
However, matrix equations constructed by conventional boundary integral
equations (CBIE) become singular under certain combinations of double node
boundary conditions. In this paper, we analyze the singular conditions of the
CBIE formulation for cases where the boundary conditions at the double node are
imposed by combinations of Dirichlet, Neumann, Robin, and interface conditions.
To address this singularity we propose the use of hypersingular integral
equations (HBIE) for wave propagation problems that obey Helmholtz equation. To
demonstrate the applicability of HBIE, we compare three types of simultaneous
equations: (i) CBIE, (ii) partial-HBIE in which HBIE is only applied to the
double nodes at corners while CBIE is applied to the other nodes, and (iii)
full-HBIE in which HBIE is applied to all nodes. Based on our numerical
results, we observe the following results. The singularity of the matrix
equations for problems with any combination of boundary conditions can be
resolved by both full-HBIE and partial-HBIE, and partial-HBIE exhibits better
accuracy than full-HBIE. Furthermore, the computational cost of partial-HBIE is
smaller than that of full-HBIE.Comment: 14 pages, 10 figures, accepted manuscript submitted to Engineering
Analysis with Boundary Elemen
Zn-induced wipeout effect on Cu NQR spectra in LaSrCuZnO
We report a systematic study of Zn-substitution effect on Cu NQR spectrum for
high superconductors LaSrCuZnO from
carrier-underdoped to -overdoped regimes (polycrystalline samples, =0.10,
0.15, and 0.20). We observed no appreciable wipeout effect for the overdoped
samples, a gradual and partial wipeout effect below about 80 K for the
optimally doped ones, and very abrupt and full wipeout effect below about 40 K
for the underdoped ones. The wipeout effect indicates a highly enhanced
spectral weight of Cu spin fluctuations at a low frequency. We associate the
wipeout effect with a Zn-induced local magnetism far above 40 K and with a
localization effect below 40 K.Comment: 2 pages, 3 figures, accepted for publication in Physica C (LT23,
Hiroshima 2002
Disposition Kinetics of Taxanes in Peritoneal Dissemination
Treatment of cancers in the abdominal cavity, such as peritoneal dissemination, is difficult, but in principle intraperitoneal administration of anticancer drugs is expected to be preferable to systemic administration. Taxane anticancer drugs are used to treat gastric cancer patients with peritoneal dissemination. They are administered as micellar preparations, Taxol and Taxotere, which consist of paclitaxel in Cremophor EL (crEL) and docetaxel in Polysorbate-80 (PS-80), respectively. In this paper we review the disposition kinetics of taxane anticancer drugs after intraperitoneal administration in peritoneal dissemination patients and animal models and also discuss the effect of the surfactant vehicle on the behavior of taxanes
Wavefront restoration from lateral shearing data using spectral interpolation
Although a lateral-shear interferometer is robust against optical component
vibrations, its interferogram provides information about differential
wavefronts rather than the wavefronts themselves, resulting in the loss of
specific frequency components. Previous studies have addressed this limitation
by measuring four interferograms with different shear amounts to accurately
restore the two-dimensional wavefront. This study proposes a technique that
employs spectral interpolation to reduce the number of required interferograms.
The proposed approach introduces an origin-shift technique for accurate
spectral interpolation, which in turn is implemented by combining two methods:
natural extension and least-squares determination of ambiguities in uniform
biases. Numerical simulations confirmed that the proposed method accurately
restored a two-dimensional wavefront from just two interferograms, thereby
indicating its potential to address the limitations of the lateral-shear
interferometer.Comment: 11 pages, 6 figure
中性子および光量子放射化分析における妨害核反応の定量的評価と岩石試料及び生物試料の多元素同時分析への応用
取得学位:博士(理学),学位授与番号:博乙第193号,学位授与年月日:平成11年9月30日,学位授与年:199
40 Gbit/sチャンネルベース大容量光ネットワークのための帯域制御RZ符号化光伝送方式に関する研究
学位の種別: 論文博士審査委員会委員 : (主査)東京大学教授 菊池 和朗, 東京大学教授 山下 真司, 東京大学准教授 小関 泰之, 東京大学准教授 種村 拓夫, 東京大学教授 浅見 徹University of Tokyo(東京大学
One-pot stereoselective synthesis of 2-acylaziridines and 2-acylpyrrolidines from N-(propargylic)hydroxylamines
The stereoselective direct transformation of N-(propargylic)hydroxylamines into cis-2-acylaziridines was achieved by the combined use of AgBF4 and CuCl. Copper salts were found to promote the transformation of the intermediary 4-isoxazolines into 2-acylaziridines and both 3-aryl- and 3-alkyl-substituted 2-acylaziridines could be prepared by using this method. Furthermore, subsequent 1,3-dipolar cycloaddition of azomethine ylides that were generated in situ from the intermediary 2-acylaziridines with maleimides was achieved in a stereoselective one-pot procedure to afford the corresponding 2-acylpyrrolidines, which consisted of an octahydropyrrolo[3,4-c]pyrrole skeleton. Love the way ylide: The transformation of N-(propargylic) hydroxylamines into cis-2-acylaziridines and subsequent 1,3-dipolar cycloaddition of the in situ generated azomethine ylides with maleimides stereoselectively afforded 2-acylpyrrolidines. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
A Synthetic Multidomain Peptide That Drives a Macropinocytosis-Like Mechanism for Cytosolic Transport of Exogenous Proteins into Plants
Direct delivery of proteins into plants represents a promising alternative to conventional gene delivery for probing and modulating cellular functions without the risk of random integration of transgenes into the host genome. This remains challenging, however, because of the lack of a protein delivery tool applicable to diverse plant species and the limited information about the entry mechanisms of exogenous proteins in plant cells. Here, we present the synthetic multidomain peptide (named dTat-Sar-EED4) for cytosolic protein delivery in various plant species via simple peptide-protein coincubation. dTat-Sar-EED4 enabled the cytosolic delivery of an active enzyme with up to ∼20-fold greater efficiency than previously described cell-penetrating peptides in several model plant systems. Our analyses using pharmacological inhibitors and transmission electron microscopy revealed that dTat-Sar-EED4 triggered a unique endocytic mechanism for cargo protein internalization. This endocytic mechanism shares several features with macropinocytosis, including the dependency of actin polymerization, sensitivity to phosphatidylinositol-3 kinase activity, and formation of membrane protrusions and large intracellular vesicles (>200 nm in diameter), even though macropinocytosis has not been identified to date in plants. Our study thus presents a robust molecular tool that can induce a unique cellular uptake mechanism for the efficient transport of bioactive proteins into plants
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