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Search Results: 1 - 10 of 70 matches for " Rintaro Kozuma "
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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.
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.
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.
Observation of Topological and Parity-dependent Phase of $m=0$ Spin States
Koji Usami,Mikio Kozuma
Physics , 2007, DOI: 10.1103/PhysRevLett.99.140404
Abstract: A Ramsey interrogation scheme was used to measure the phase shift of laser-cooled $^{87}$Rb clock-transition pseudospins arising as a result of a reversal of a bias magnetic field, i.e., $\textbf{B} \to -\textbf{B}$, during the interrogation. While no phase shift occurred when the reversal was sudden, the Ramsey fringes were shifted by a factor of $\pi$ when the reversal was adiabatic. We thus verified the prediction that the spin states $|F,m=0 >$ acquire a purely topological and parity-dependent phase factor of $(-1)^{F}$ as a result of $\textbf{B} \to -\textbf{B}$.
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.
Measure of synonymous codon usage diversity among genes in bacteria
Haruo Suzuki, Rintaro Saito, Masaru Tomita
BMC Bioinformatics , 2009, DOI: 10.1186/1471-2105-10-167
Abstract: The application of Dmean to 268 bacterial genomes shows that in bacteria with extremely biased genomic G+C compositions there is little diversity in synonymous codon usage among genes. Furthermore, our findings contradict previous reports. For example, a low level of diversity in codon usage among genes has been reported for Helicobacter pylori, but based on Dmean, the diversity level of this species is higher than those of more than half of bacteria tested here. The discrepancies between our findings and previous reports are probably due to differences in the methods used for measuring codon usage diversity.We recommend that Dmean be used to measure the diversity level of codon usage among genes. This measure can be applied to other compositional features such as amino acid usage and dinucleotide relative abundance as a genomic signature.Most amino acids can be encoded by more than one codon (i.e., a triplet of nucleotides); such codons are described as being synonymous, and usually differ by one nucleotide in the third position. In most bacteria, alternative synonymous codons are not used with equal frequencies. Grantham et al. [1] showed that genes from same species often show similar patterns of codon usage, and proposed the 'genome hypothesis' that there exists a species-specific pattern of codon usage. Then, it was shown that in many organisms there are also considerable differences in codon usage among genes within a genome [2]. Previous analyses of codon usage diversity in bacteria have mostly focused on individual genomes, with no quantitative attempt to compare the diversity levels among different genomes. For comparative genomic analysis, it is desirable to quantify the level of codon usage diversity among genes in such a way that the estimates could be compared among genomes.Different factors have been proposed to explain the preferential usage of a subset of synonymous codons, including biased mutation pressure (genome-wide mutational bias toward G/C or
Variation in the Correlation of G + C Composition with Synonymous Codon Usage Bias among Bacteria
Haruo Suzuki, Rintaro Saito, Masaru Tomita
EURASIP Journal on Bioinformatics and Systems Biology , 2007, DOI: 10.1155/2007/61374
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