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323 results on '"Yamaguchi, Keiko"'

103. Modeling of surface roughness effects on glaze ice accretion

Author

Hansman, R. John, Jr, Yamaguchi, Keiko, Berkowitz, Brian, and Potapczuk, M

Subjects
Air Transportation And Safety
Abstract

The cause and effects of roughness on accreting glaze ice surfaces were studied with microvideo observations. Distinct zones of surface water behavior were observed, including a smooth wet zone in the stagnation region with a uniform water film, a rough zone where surface tension effects caused coalescence of surface water into stationary beads, and a zone where roughness elements grow into horn shapes. In addition, a zone where surface water ran back as rivulets and a dry zone where rime feathers formed were observed. The locations and behaviors of these zones are discussed. A simple multizone modification to the glaze ice accretion model is proposed to include spatial variability in surface roughness. Two test cases using the multizone model showed significant improvements for the prediction of glaze ice shapes.

Published
1989

107. Morphological differences and genetic differentiation level between populations of Trapezium liratum in Lake Obuchi and Lake Nakaumi-Species redetermination of Trapezium liratum inhabiting Lake Obuchi-

Author

KONDO, Kunio, primary, UEDA, Shinji, additional, YAMAGUCHI, Keiko, additional, HATSUMI, Machiko, additional, KONO, Masatake, additional, KOBAYASHI, Daisuke, additional, CHIKUCHI, Yuki, additional, INABA, Jiro, additional, and OHMOMO, Yoichiro, additional

Published
2005
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111. Vertical zonation and aggregated distribution of the Manila clam on subtidal sand flats in a coastal brackish lagoon along the Sea of Japan.

Author

Yamada, Katsumasa, Miyamoto, Yasushi, Fujii, Chisato, Yamaguchi, Keiko, and Hamaguchi, Masami

Subjects
INTERTIDAL zonation, MANILA clam, BRACKISH waters, AQUATIC habitats
Abstract

The Manila clam, Ruditapes philippinarum, has maintained small-sized populations in a semi-enclosed brackish lake along the Sea of Japan, the Honjo area of Lake Nakaumi, although the environment and biota of this area have changed dramatically due to a large-scale reclamation project. There should be underlying processes that enable the restoration of this species from small-sized populations, such as the existence of source ( i.e. reproductive) populations in other areas and depth zones of the lake. However, there has been no robust, properly designed evaluation of the distribution of the Manila clam in the subtidal sand flats. In order to elucidate the possible mechanisms that allow for the persistence of populations of the Manila clam, we examined the spatiotemporal and vertical variation in distributions of 0-age clams in the subtidal zone of sand flats. Seasonal effects on population variations showed erratic changes among depth zones without a decreasing trend along the depth gradient. Further, many local populations became extinct even in the shallower zones due to seasonal (summer) hypoxia at deeper zones and hypoxia by the accumulation of key benthic species ( Asian mussel and decaying macroalgae) in mats at shallower zones. A few surviving local populations were stable with a spatial-fragmental (patchy) distribution, associated with fragmented accumulations of Asian mussels and macroalgae. Efforts to maintain stable populations and to restore this species in the subtidal area may depend on these small, restricted, patchy local populations. These findings suggest that high fertility and productivity of the Manila clam as well as patchy distribution of small populations may contribute to the maintenance of the population and the avoidance of extinction (by spatially diffusing the risk of extinction) in harsh environments resulting from the reclamation project. [ABSTRACT FROM AUTHOR]

Published
2014
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127. Estimating a change point in the long memory parameter.

Author

Yamaguchi, Keiko

Subjects
*ESTIMATION theory, *PARAMETER estimation, *STOCHASTIC convergence, *CONFIDENCE intervals, *SIMULATION methods & models, *WATER levels
Abstract

We propose an estimator of change point in the long memory parameter d of an ARFIMA( p, d, q) process using the sup Wald test. We derive the consistency and the rate of convergence of the estimator for the time of change. The convergence rate of our change point estimator depends on the magnitude of a shift. Furthermore, we obtain the limiting distribution of our change point estimator without depending on the distribution of the process. Therefore, we can construct confidence intervals for the change point. Simulations show the validity of the asymptotic theory of our estimator if the sample size is large enough. We apply our change point estimator to the yearly Nile river minimum water level. [ABSTRACT FROM AUTHOR]

Published
2011
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128. The Effects of High Hydrostatic Pressure Treatment on the Flavor and Color of Grated Ginger.

Author

Yamaguchi, Keiko, Kato, Tatsuo, Noma, Seiji, Igura, Noriyuki, and Shimoda, Mitsuya

Subjects
*COLOR of plants, *PHYSIOLOGICAL effects of hydrostatic pressure, *GINGER, *DEHYDROGENASES, *TERPENES
Abstract

The article presents a study which examines the effects of high hydrostatic pressure (HHP) application on the color and flavor of grated ginger. The study assesses changes of volatile compounds in the HHP treated ginger. Result shows that HHP treatment reduces inactivation of geraniol dehydrogenase (GeDH) to less than 5% and polyphenol oxidase (PPO) to 37%. Moreover , terpene aldehydes nearly vanished during the process, while the browning of the ginger was only noticed during heat treatment.

Published
2010
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135. Development of copper-mediated allylation of γ-activated-α,β-unsaturated lactam toward peptide mimetic synthesis

Author

Sasaki, Yoshikazu, Yamaguchi, Keiko, Tsuji, Takashi, Shigenaga, Akira, Fujii, Nobutaka, and Otaka, Akira

Subjects
*PEPTIDES, *LACTAMS, *CHEMICAL reactions, *CHEMICAL processes
Abstract

Abstract: Reactions of γ-activated-α,β-unsaturated lactams with allylboronate in the presence of LiOi-Pr and CuX (stoichiometric or catalytic amount) proceed in an anti-SN2′ manner to yield α-allylated compounds that serve as a potential synthetic intermediate for cis-aminoacyl-Pro mimetics. [Copyright &y& Elsevier]

Published
2007
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