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American Journal of Plant Sciences 2012年第1期3卷 110-113页

作者： Hiroshi Hayakawa Tunala yukio minamiya Katsura Ito Stephan Gale Jun Yokoyama Ryo Arakawa Tatsuya Fukuda 不详

The comparative morphology and anatomy of leaves in the serpentine endemic Aster hispidus Thunb. var. leptocladus (Makino) Okuyama and its close relative A. hispidus var. hispidus were examined. Our morphological analysis revealed that the leaves of A. hispidus var. leptocladus were significantly smaller and narrower than those of A. hispidus var. hispidus. In particular, our anatomical analysis indicated that a decreased cell number of the horizontal axis of a leaf was involved in A. hispidus var. leptocladus. This was the same process as the changing pattern of the leaves of rheophytic species, and so, similar morphological leaf modifications occurred under different selection pressures of the serpentine soil and flooding frequency of river-stream.

关键词： Anatomical Analysis Aster hispidus var. leptocladus Cell Number Minitualization Serpentine Stenophyllization

Phylogeography of Asparagus schoberioidesKunth (Asparagaceae) in Japan

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American Journal of Plant Sciences 2011年第6期2卷 781-789页

作者： Tatsuya Fukuda In-Ja Song Hokuto Nakayama Takuro Ito Akira Kanno Hiroshi Hayakawa yukio minamiya Jun Yoko Yama 不详

To describe the phylogeographic structures of Asparagus schoberioides Kunth (Asparagaceae) in Japan, we investigated its nucleotide sequence variations with respect to its geographic distribution pattern. Sequencing of the internal transcribed spacer (ITS) 1 region in 29 samples of A. schoberioides revealed 20 polymorphic nucleotide sites. As a result, the 29 samples of A. schoberioides fell into 15 distinct haplotypes and phylogenetic analyses revealed these haplotypes fell into two major clades, Clade 1 and Clade 2. The haplotypes of Clade 1 were distributed chiefly along the Pacific Ocean side of Japan, while those of Clade 2 occurred mainly along the Japan Sea side. This result suggests that A. schoberioides has migrated via two routes in Japan.

关键词： Asparagus schoberioides Internal Transcribed Spacer (ITS) Phylogeny Phylogeography

Interspecific Hybridization between Arisaema sikokianumand A. serratum(Araceae) Confirmed through Nuclear and Chloroplast DNA Comparisons

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American Journal of Plant Sciences 2011年第4期2卷 521-526页

作者： Hiroshi Hayakawa Hidenori Hamachi Kanako Matsuyama Yuko Muramatsu yukio minamiya Katsura Ito Jun Yokoyama Tatsuya Fukuda Faculty of Agriculture Kochi University Nankoku Japan

A morphologically intermediate plant between Arisaema sikokianum Franch. et Sav. and A. serratum (Thunb.) Schott has been newly found in Kochi Prefecture, Shikoku, Japan. The putative hybrid has the intermediate morphological characteristics of the parental species. Molecular analysis using PCR-RFLP of internal transcribed spacer (ITS) in nuclear DNA (nrDNA) indicates that the putative hybrid has a combined pattern of the two putative parent species. Moreover, the sequence result of chloroplast DNA (cpDNA) of the putative hybrid was identical to that of A. sikokianum. These results suggest that the putative hybrid is a hybrid between A. sikokianum and A. serratum and that it was formed by interactive gene exchanging via pollens from A. serratum to A. sikokianum. It is the first record of a hybrid between A. sikokianum and A. serratum.

关键词： Araceae Arisaema A. serratum A. sikokianum Chloroplast DNA Interspecific Hybrid Molecular Analysis Nuclear DNA

Correlation between Sex Stages and Leaf Numbers in Arisaema tosaenseMakino (Araceae)

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American Journal of Plant Sciences 2012年第1期3卷 114-118页

作者： Yuko Muramatsu Kanako Matsuyama Hiroshi Hayakawa yukio minamiya Katsura Ito Ryo Arakawa Tatsuya Fukuda 不详

Arisaema tosaense Makino develops either 1 or 2 leaves during both the male and female phases. To clarify the relationship between growth stage (sexual stage) and leaf number in this species, we conducted morphological analysis using A. tosaense, A. japonicum Bulme, A. sikokianum French. & Sav., and A. ringens (Thunb.) Schott. We found that increase in size of pseudostem of these Arisaema species is correlated to changes in the growth stage from sterile to male and from male to female phases. In particular, 1-leaf individuals of A. tosaense appeared at the beginning of both male and female phases, suggesting that they contribute to the earlier appearance of the fertile phase from sterile

关键词： Araceae Arisaema tosaense Fertile Phases Leaf Number Morphology

Nucleotide Sequence Variations in a Medicinal Relative of Asparagus, Asparagus cochinchinensis(Lour.) Merrill (Asparagaceae)

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American Journal of Plant Sciences 2011年第6期2卷 765-775页

作者： Tatsuya Fukuda In-Ja Song Takuro Ito Hiroshi Hayakawa yukio minamiya Akira Kanno Hokuto Nakayama Jun Yokoyama 不详

To determine the eVolutionary history of Asparagus cochinchinensis (Asparagaceae), we investigated the geographic pattern of its nucleotide sequence variations in Japan, Taiwan, South Korea and China. We found 21 polymorphic nucleotide sites by sequencing the internal transcribed spacer (ITS) region, which gave rise to a total of 15 haplotypes, labeled A to O. The A-type was found only in inland China (Guizhou and Sichuan), and the other haplotypes in China extended to several lineages;therefore, A. cochinchinensis may have its origin in the interior of China. The I-type has large distribution area and it also experienced a quick expansion in relative recent years. Haplotype differentiation was observed between the eastern and western side of the Central Mountain Ridge in Taiwan. Two lineages were found in Japan, one in the Yaeyama Islands and the other in remaining areas of Japan, implying that A. cochinchinensis independently colonized in Japan at least twice.

关键词： Asparagus cochinchinensis Internal Transcribed Spacer (ITS) Phylogeny Phylogeography

Introgressive Hybrids of Arisaema sikokianumand A. tosaense(Araceae) Confirmed through Nuclear and Chloroplast DNA Comparisons

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American Journal of Plant Sciences 2011年第3期2卷 303-307页

作者： Hiroshi Hayakawa Hidenori Hamachi Kanako Matsuyama Yuko Muramatsu yukio minamiya Katsura Ito Jun Yokoyama Tatsuya Fukuda 不详

Morphologically putative introgressive hybrids of Arisaema sikokianum Franch. et Sav. and A. tosaense Makino were newly found in Kochi and Tokushima Prefectures in Japan. All the individuals have the same morphological characteristics as A. tosaense excluding a purple spathe. Molecular analysis using PCR-RFLP of internal transcribed spacer (ITS) in nuclear DNA (nrDNA) indicates that these putative introgressive hybrids have the same pattern as A. tosaense. Moreover, the sequences of chloroplast DNA (cpDNA) of the putative introgressive hybrids were identical to A. sikokianum from Kochi Prefecture and A. tosaense from Tokushima Prefecture. The results suggest that the plants are introgressive hybrids of A. sikokianum and A. tosaense and that they have highly exchanged genes with A. tosaense.

关键词： Araceae Arisaema A. sikokianum A. tosaense Chloroplast Capture Introgression ITS Molecular Analysis PCR-RFLP Trn

Creep and creep-fatigue behavior of high chromium steel weldment

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Acta Metallurgica Sinica(English Letters) 2011年第3期24卷 175-182页

作者： yukio TAKAHASHI Masaaki TABUCHI Materials Science Laboratory Central Research Institute of Electric Power Industry National Institute of Material Sciences

Strength of welded joints of high chromium steels is one of the important concerns for fabricators and operators of ultra supercritical thermal power plants. A number of creep as well as creep-fatigue tests with tensile hold have been carried out on the welded joints of two types of high chromium steels widely used in Japan, i.e. Grade 91 and 122 steels. It was found that failure occurred in fine grain heat-affected zone in all the creep-fatigue tests, even at a relatively low temperature and fairly short time where failure occurred in plain base metal region in simple creep testing. Four procedures were used to predict failure lives and their results were compared with the test results. A newly proposed energy-based approach gave the best estimation of failure life, without respect of the material and temperature.

关键词： Creep Creep-fatigue High chromium steel Life prediction Welded joint

ESTIMATION OF CHAIN REACTION BANKRUPTCY STRUCTURE BY CHANCE DISCOVERY METHO—WITH TIME ORDER METHOD AND DIRECTED KEYGRAPH

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Journal of Systems Science and Systems Engineering 2007年第4期16卷 489-498页

作者： Shinichi GODA yukio OHSAWA School of Engineering The University of Tokyo113-8656 Japan

Chain reaction bankruptcy is regarded as common phenomenon and its effect is to be taken into account when credit risk portfolio is analyzed. But consideration and modeling of its effect leave much room for improvement. That is mainly because method for grasping relations among companies with limited data is underdeveloped. In this article, chance discovery method is applied to estimate industrial relations that are to include companies＇ relations that transmit chain reaction of bankruptcy. Time order method and directed KeyGraph are newly introduced to distinguish and express the time order among defaults that is essential information for the analysis of chain reaction bankruptcy. The steps for the data analysis are introduced and result of example analysis with default data in Kyushu, Japan, 2005 is presented. The structure estimated by the new method is compared with the structure of actual account receivable holders of bankrupted companies for evaluation.

关键词： Chance discovery credit risk chain reaction bankruptcy

PREDICTING RELEVANT EMPTY SPOTS IN SOCIAL INTERACTION

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Journal of Systems Science & Complexity 2008年第2期21卷 161-171页

作者： Yoshiharu MAENO yukio OHSAWA Graduate School of Systems Management Tsukuba University School of Engineering University of Tokyo

An empty spot refers to an empty hard-to-fill space which can be found in the records of the social interaction, and is the clue to the persons in the underlying social network who do not appear in the records. This contribution addresses a problem to predict relevant empty spots in social interaction. Homogeneous and inhomogeneous networks are studied as a model underlying the social interaction. A heuristic predictor function method is presented as a new method to address the problem. Simulation experiment is demonstrated over a homogeneous network. A test data set in the form of market baskets is generated from the simulated communication. Precision to predict the empty spots is calculated to demonstrate the performance of the presented method.

关键词： Communication empty spot predictor function social interaction social network.

A fine-grained evaluation of social vulnerability to COVID-19,healthcare access and built environmental disparities in Tokyo,Japan

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International Journal of Digital Earth 2022年第1期15卷 2006-2027页

作者： Siqin Wang yukio Sadahiro Graduate School of Interdisciplinary Information Studies The University of TokyoTokyoJapan School of Earth and Environmental Sciences The University of QueenslandBrisbaneQLDAustralia

Measuring vulnerability to COVID-19 and healthcare accessibility at the fine-grained level serves as the foundation for spatially explicit health planning and policy making in response to future public health ***,the evaluation of vulnerability and healthcare accessibility is insufficient in Japan-a nation with high population density and super-aging *** on the 2022 census data,transport network,medical and digital cadastral data,land use maps,and points of interest data,our study extends the concept of vulnerability in the context of COVID-19 and constructs the first fine-grained measure of vulnerability and healthcare accessibility in Tokyo Metropolis,Japan-the most populated metropolitan region in the *** delineate the vulnerable neighbourhoods with low healthcare access and further evaluate the disparity in healthcare access and built environment of areas at different levels of *** outcome datasets and findings provide nuanced and timely evidence to government and health authorities to have a holistic and latest understanding of social vulnerability to COVID-19 and healthcare access at a fine-grained *** analytical framework can be employed in different geographic contexts,guiding through place-based health planning and policy making in the post-COVID era and beyond.

关键词： COVID-19 vulnerability healthcare access built environment network analysis Tokyo metropolis