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Search Results: 1 - 10 of 2493 matches for " Rintaro Yoshida "
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On some questions of Fisk and Br?ndén
Rintaro Yoshida
Mathematics , 2010,
Abstract: P. Br\"and\'en recently proved a conjecture due to S. Fisk, R. P. Stanley, P. R. W. McNamara and B. E. Sagan. In addition, P. Br\"and\'en gave a partial answer to a question posed by S. Fisk regarding the distribution of zeros of polynomials under the action of certain non-linear operators. In this paper, we give an extension to a result of P. Br\"and\'en, and we also answer a question posed by S. Fisk.
Checkpoint with forkhead-associated and ring finger promoter hypermethylation correlates with microsatellite instability in gastric cancer
Eiji Oki, Yan Zhao, Rintaro Yoshida, Takanobu Masuda, Koji Ando, Masahiiko Sugiyama, Eriko Tokunaga, Masaru Morita, Yoshihiro Kakeji, Yoshihiko Maehara
World Journal of Gastroenterology , 2009,
Abstract: AIM: To examine the methylation status of the promoter region of the checkpoint with forkhead-associated and ring finger (CHFR) and microsatellite mutator status in 59 primary gastric cancers.METHODS: We investigated the promoter methylation of CHFR in 59 cases of gastric cancer using methylation-specific PCR. Five microsatellite loci were analyzed using high-intensity microsatellite analysis reported previously, and p53 gene mutations were investigated by direct sequencing.RESULTS: Twenty cases (33.9%) showed promoter methylation and no relation was observed with the clinicopathological factors. We found that the promoter methylation of CHFR was frequently accompanied with microsatellite instability (MIN). Seven of 20 (35.0%) cases showed MIN in hypermethylation of the CHFR tumor, while three of 39 (7.7%) cases showed MIN in the non-methylated CHFR tumor (P < 0.01). However, we failed to find any relationship between CHFR methylation and p53 mutation status.CONCLUSION: The coordinated loss of both the mitotic check point function and mismatch repair system suggests the potential to overcome the cell cycle check point, which may lead to an accumulation of mutations. However, the p53 mutation was not related to hypermethylation of the CHFR promoter and MIN, which indicates that an abnormality in p53 occurs as an independent process from the mismatch repair deficiency in carcinogenesis.
Self-initiated Self-repair Attempts by Japanese High School Learners While Speaking English
Rintaro Sato
Brain. Broad Research in Artificial Intelligence and Neuroscience , 2012,
Abstract: In Japanese high school English classes, students are often left to have interactions or perform communicative activities not with a teacher but with other students due to a large class size. In the situation, students are ideally notice their own insufficient utterances in order to carry out self-initiated self-repair. This study investigated self-initiated self-repair attempts and their effects on Japanese high school learners. Thirty-two Japanese high school students with low-intermediate English ability and a native speaker of English participated in the study, with the native speaker interviewing the students. The students’ utterances were quantitatively and qualitatively analyzed, and it was found that: self-initiated self-repair occurred frequently and, in general, successfully; error repair was most frequently recorded; the success rate of lexical repair was the lowest. Findings observed during the students’ self-initiated self-repair attempts are discussed, followed by discussion of their possible effects. Finally, suggestions are given based on the pedagogical implications from the study.
Elliptic curves related to cyclic cubic extensions
Rintaro Kozuma
Mathematics , 2007,
Abstract: The aim of this paper is to study certain family of elliptic curves $\{\mathscr{X}_H\}_H$ defined over a number field $F$ arising from hyperplane sections of some cubic surface $\mathscr{X}/F$ associated to a cyclic cubic extension $K/F$. We show that each $\mathscr{X}_H$ admits a 3-isogeny $\phi$ over $F$ and the dual Selmer group $S^{(\hat{\phi})}(\hat{\mathscr{X}_H}/F)$ is bounded by a kind of unit/class groups attached to $K/F$. This is proven via certain rational function on the elliptic curve $\mathscr{X}_H$ with nice property. We also prove that the Shafarevich-Tate group $\text{\cyr X} (\hat{\mathscr{X}_H}/\rat)[\hat{\phi}]$ coincides with a class group of $K$ as a special case.
Coefficient estimates of analytic endomorphisms of the unit disk fixing a point with applications to concave functions
Rintaro Ohno,Toshiyuki Sugawa
Mathematics , 2015,
Abstract: In this note, we discuss the coefficient regions of analytic self-maps of the unit disk with a prescribed fixed point. As an application, we solve the Fekete-Szeg\H{o} problem for normalized concave functions with a prescribed pole in the unit disk.
On the second Hankel determinant of concave functions
Rintaro Ohno,Toshiyuki Sugawa
Mathematics , 2015,
Abstract: In the present paper, we will discuss the Hankel determinants $H(f) =a_2a_4-a_3^2$ of order 2 for normalized concave functions $f(z)=z+a_2z^2+a_3z^3+\dots$ with a pole at $p\in(0,1).$ Here, a meromorphic function is called concave if it maps the unit disk conformally onto a domain whose complement is convex. To this end, we will characterize the coefficient body of order 2 for the class of analytic functions $\varphi(z)$ on $|z|<1$ with $|\varphi|<1$ and $\varphi(p)=p.$ We believe that this is helpful for other extremal problems concerning $a_2, a_3, a_4$ for normalized concave functions with a pole at $p.$
Effects of flooding on arbuscular mycorrhizal colonization and root-nodule formation in different roots of soybeans  [PDF]
Rintaro Hattori, Atsushi Matsumura, Kenji Yamawaki, Arata Tarui, Hiroyuki Daimon
Agricultural Sciences (AS) , 2013, DOI: 10.4236/as.2013.412090

In several countries in monsoon Asia, soybean crops are cultivated in upland fields converted from paddies. In such fields, excess soil water often induces extensive damage followed by lower nutrient uptake by this crop. In this study, the effects of flooding during the early growth stage of pot-grown soybeans on arbuscular mycorrhizal (AM) colonization and root nodule formation were investigated. Twenty days after sowing cv. Fukuyutaka, half of the pots were flooded (flooding) and the other half were left unflooded (irrigation). The plants were sampled after 39 days of flooding. Typical morphological alterations to flooding were found, including an enlarged hypocotyl diameter and partial cracking of the surface tissues, and adventitious roots developed on the soil surface. The primary and lateral roots were shorter and the adventitious roots were longer in flooding than in irrigation. In flooding, the ratio of the aerenchyma area to the stele area was 82.5% in adventitious roots. The AM colonization ratio in flooding was significantly lower than in irrigation. The ratio in flooding was markedly low in the primary and lateral roots, but it was not necessarily low in the adventitious roots. Root nodules were formed on the adventitious roots but not on the primary and lateral roots, especially in flooding. These results showing different rates of AM colonization and root nodule formation between the two different types of roots improve the understanding of responses of soybeans grown in paddy-rotated upland fields.

The Novel Pyruvated Glucogalactan Sulfate Isolated from the Red Seaweed, Hypnea pannosa  [PDF]
Masakuni Tako, Rintaro Ohtoshi, Kazutaka Kinjyo, Shuntoku Uechi
Advances in Biological Chemistry (ABC) , 2016, DOI: 10.4236/abc.2016.63010
Abstract: The polysaccharide was isolated from Hypnea pannosa which was grown in Okinawa, Japan. The yield of the polysaccharide was 17.2%, and the total carbohydrates, pyruvic acid, sulfuric acid and ash contents were 55.2%, 3.8%, 35.2% and 24.3%, respectively. 3,6-Anhydro-α-D-galactose, β-D-galactose, α-D-galactose and D-glucose were identified by liquid and thin-layer chromatography. Fourier transform infrared (FTIR) spectra of the polysaccharide resembled that of ι-carrageenan. From the 1H- and 13C-NMR spectra, 1,3-linked β-D-galactose, 1,4-linked anhydro-α-D-galactose, 1,4-linked α-D-galactose, 1,4-linked β-D-glucose and pyruvic acid (carboxyl acetal, methyl proton and methyl carbon) were assigned. Methylation analysis revealed terminal D-galactose 0.1 mol), 1,4-linked D-glucose (1.0 mol) and 1,2,3,4,6-linked D-galactose (3.7 mol) for native polysaccharide, and terminal D-galactose, 1,4-linked D-galactose (1.9 mol), 1,4-linked D-glucose (1.0 mol), 1,3- linked D-galactose (1.7 mol), and 1,3,4,6-linked D-galactose (0.3 mol) which substituted with pyruvate group at 4 and 6 positions for desulfated polysaccharide. The polysaccharide was the novel pyruvated glucogalactan sulfate, the structure of which was proposed.
Nitroxide-Mediated Photo-Controlled/Living Radical Polymerization of Methacrylic Acid  [PDF]
Eri Yoshida
Open Journal of Polymer Chemistry (OJPChem) , 2013, DOI: 10.4236/ojpchem.2013.31004

The photo-controlled/living radical polymerization of methacrylic acid (MAA) was performed at room temperature by irradiation with a high-pressure mercury lamp using azo initiators and 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl as the mediator in the presence of (4-tert-butylphenyl)diphenylsulfonium triflate (tBuS) as the accelerator. Whereas the bulk polymerization yielded polymers with a bimodal molecular weight distribution in both the absence and presence of tBuS, the solution polymerization in methanol produced unimodal polymers with the molecular weight distribution of 2.0 - 2.3 in the presence of tBuS. The molecular weight distribution of the resulting poly (MAA) decreased with an in- crease in tBuS. The dilution of the monomer concentration also reduced the molecular weight distribution. The use of the initiator with a low 10-h half-life temperature also effectively controlled the molecular weight. The livingness of the polymerization was confirmed by obtaining linear increases in the first-order conversion versus time, the molecular weight versus the conversion, and the molecular weight versus the reciprocal of the initiator concentration.

Elucidation of Acceleration Mechanisms by a Photosensitive Onium Salt for Nitroxide-Mediated Photocontrolled/Living Radical Polymerization  [PDF]
Eri Yoshida
Open Journal of Polymer Chemistry (OJPChem) , 2014, DOI: 10.4236/ojpchem.2014.43006

The acceleration mechanisms by a photosensitive onium salt for the nitroxide-mediated photocontrolled/living radical polymerization (photo-NMP) were determined. The photo-NMP of methyl methacrylate was performed by irradiation at room temperature using 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl (MTEMPO) as the mediator and (2RS, 2’RS)-azobis(4-methoxy-2,4-dimethylvaleronitrile) as the initiator. The polymerization was accelerated in the presence of (4-tertbutylphenyl)diphenylsulfonium triflate (tBuS) to produce a polymer with a molecular weight distribution as narrow as the polymerization in its absence. (±)-Camphor-10-sulfonic acid or 2-fluoro-1-methylpyridinium p-toluenesulfonate had no effect on the polymerization speed, suggesting that tBuS did not serve as the photo-acid generator for the photo-NMP. It was found that the acceleration of the polymerization was based on the electron transfer from MTEMPO into tBuS in the excited state to temporarily generate a free radical propagating chain end and an oxoaminium salt (OAS), the one-electron oxidant of MTEMPO. This electron transfer mechanism was verified on the basis of the fact that the photo-NMP in the presence of

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