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31.
Yasushi Sakurai Masatoshi Yoshikawa Shunsuke Uemura Haruhiko Kojima 《The VLDB Journal The International Journal on Very Large Data Bases》2002,11(2):93-108
We propose a novel index structure, the A-tree (approximation tree), for similarity searches in high-dimensional data. The
basic idea of the A-tree is the introduction of virtual bounding rectangles (VBRs) which contain and approximate MBRs or data
objects. VBRs can be represented quite compactly and thus affect the tree configuration both quantitatively and qualitatively.
First, since tree nodes can contain a large number of VBR entries, fanout becomes large, which increases search speed. More
importantly, we have a free hand in arranging MBRs and VBRs in the tree nodes. Each A-tree node contains an MBR and its children
VBRs. Therefore, by fetching an A-tree node, we can obtain information on the exact position of a parent MBR and the approximate
position of its children. We have performed experiments using both synthetic and real data sets. For the real data sets, the
A-tree outperforms the SR-tree and the VA-file in all dimensionalities up to 64 dimensions, which is the highest dimension
in our experiments. Additionally, we propose a cost model for the A-tree. We verify the validity of the cost model for synthetic
and real data sets.
Edited by T. Sellis. Received: December 8, 2000 / Accepted: March 20, 2002 Published online: September 25, 2002 相似文献
32.
Sone T Hanamizu T Ichioka M Yokokura T Yoshikawa S Kondo-Yanai N Hiraki Y Esumi K 《International journal of cosmetic science》1999,21(1):23-31
The moisturizing effect of vesicles formed from monoglycerides on human skin was studied by measurement of conductance on and transepidermal waterloss from the skin surface. Although sonication of the monoglycerides in water with Ca2+ gave multilamellar vesicles, the lamellar structure of the vesicles disappeared during their storage without any other additive. With the addition of poly(vinylpyrrolidone) after the sonication, the stability of the vesicles increased and their lamellar structure was maintained for 3 months at 40 degrees C. These vesicles led to a significantly higher water content of the stratum corneum of human skin compared with non-lamellar monoglyceride, and consequently they improved rough human skin. 相似文献
33.
I Kitagawa K Hori T Motozawa T Murakami M Yoshikawa 《Canadian Metallurgical Quarterly》1998,46(12):1901-1906
Friedreich's ataxia is the first known autosomal recessive disease caused by an unstable trinucleotide expansion mutation. The most frequent mutation is expansion of a GAA repeat in the first intron of gene X25. We studied transmission of the expanded GAA repeat in 37 Friedreich's ataxia pedigrees and analysed blood and sperm alleles in eight patients. We showed intergenerational instability in 84% of the alleles with an overall excess of contractions. Both contractions and expansions of the GAA repeat occurred in maternal transmission with a stronger tendency to expand for smaller repeats and to contract for longer repeats. Paternally transmitted alleles contracted only. Parental age and the intergenerational change in expansion size were directly correlated in maternal transmission and inversely in paternal transmission. The size of the GAA expansion was slightly lower in patients than heterozygous carriers. Sperm analysis confirmed the tendency to contract of paternal alleles, which was more marked with ageing. The degree of contraction of the GAA repeat in sperm was much higher than that found in intergenerational transmission and was directly related to the repeat size. A blood expanded allele reverted to normal size in the sperm of one patient. This study suggests the existence of different mutational mechanisms in Friedreich's ataxia alleles, which occur both pre- and post-zygotically. 相似文献
34.
M Yamada A Tomida H Yoshikawa Y Taketani T Tsuruo 《Canadian Metallurgical Quarterly》1996,2(2):427-432
Thioredoxin (TRX) is a widely distributed Mr 13,000 protein with a redox-active dithiol/disulfide in the active site. The TRX system, consisting of TRX, TRX reductase, and NADPH, has an intracellular reducing capacity. Another reducing capacity, glutathione (GSH), can be associated with cis-diaminedichloroplatinum (cDDP) resistance. Therefore, we examined the involvement of TRX in cDDP resistance using two cell lines designated St/DDP and HT/DDP, which were established from the human gastric cancer cell line St-4 and the colon cancer cell line HT-29. St/DDP and HT/DDP were seven and five times as resistant to cDDP as their parental lines, and the expression of TRX in these variants was increased by 2.5- and 2-fold, respectively. The expression of TRX in the complete revertant cells of St/DDP was reduced as low as that in St-4 cells. TRX reductase activity was also increased in St/DDP and HT/DDP, suggesting that activation of the TRX system was associated with in vitro-acquired cDDP resistance. Because cDDP is the first-line drug against ovarian cancer, we examined the expression of TRX in 11 human ovarian cancer cell lines not treated with cDDP in vitro. Positive correlation between TRX expression and cDDP resistance was observed in these cell lines (r = 0.76, P = 0.007). This correlation was comparable to that between GSH content and cDDP resistance (r = 0.69, P = 0.019). These results suggest a possible involvement of TRX, as well as GSH, in cDDP resistance. 相似文献
35.
Surgical treatment of Cronkhite-Canada syndrome associated with protein-losing enteropathy: report of a case 总被引:1,自引:0,他引:1
M Hanzawa N Yoshikawa T Tezuka K Konishi K Kaneko Y Akita K Mitamura A Tsunoda M Takada M Kusano 《Canadian Metallurgical Quarterly》1998,41(7):932-934
PURPOSE: The case of a patient with Cronkhite-Canada syndrome, who developed a protein-losing enteropathy, is reported. METHODS: After localization of the protein-losing region, a right colectomy was performed. RESULTS: Hypoproteinemia and ectodermal changes improved postoperatively. CONCLUSIONS: Surgery is an effective treatment for protein-losing enteropathy in Cronkhite-Canada syndrome. Ectodermal changes improve after correcting malnutrition. 相似文献
36.
37.
The letter reports a new apodisation of electrodes which provides surface-acoustic-wave filters capable of operation without apodisation loss and with sufficiently large stopband attenuation. The effectiveness of the apodisation was shown by experiments. 相似文献
38.
39.
K. Matsuda Y. Yamaguchi N. Morita T. Matsunobe M. Yoshikawa 《Thin solid films》2007,515(17):6682-6685
We have measured Raman and Electron-spin resonance (ESR) spectra of fluorine-doped SiO2 films deposited by two different methods. In high-density plasma (HDP) films, the Raman band at about 490 cm− 1 becomes drastically stronger as the F/Si ratio increases, whereas the Raman band from threefold ring defect is independent of the F/Si ratio. The unusual increase of the intensity of the 490 cm− 1 band in HDP films has been interpreted in terms of the existence of Si-Si clusters. From a comparison between Raman spectra of HDP film and plasma chemical vapor deposition using tetraethoxysilane (p-TEOS) film with the same F/Si ratios it has been found that HDP film has more Si-Si bonds and threefold ring defects than p-TEOS film. Furthermore, the polarized Raman spectra in the 810 cm− 1 bands indicate that inhomogeneous SiO2 clusters of various sizes should exist in the network structure of HDP film. The result of the ESR measurement shows that HDP films have fewer dangling bonds than p-TEOS films. It is considered that many Si-Si clusters, threefold ring defects, and inhomogeneous SiO2 cluster sizes, and the few dangling bonds in HDP films give rise to the film properties of low stress, good adhesion with Si substrate, and low water permeation. 相似文献
40.
Harunori Yoshikawa Pascal Kurowski Philippe Petitjeans Farzam Zoueshtiagh Hervé Caps 《Microgravity science and technology》2007,19(3-4):155-156
The response of an air bubble surrounded by a liquid in a sealed cell submitted to vibrations was investigated experimentally under microgravity conditions and compared to experiments under normal gravity conditions. As in normal gravity [1], it was observed that the bubble split into smaller parts when the acceleration of the vibrations reached a threshold. This threshold in microgravity is substantially smaller than that in normal gravity. Experimental results are presented in terms of an acceleration based Bond number which has been found to characterize the bubble behaviour in the laboratory experiments [1]. 相似文献