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Search Results: 1 - 10 of 38871 matches for " Jun-ichi Ohkubo "
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Power-law behavior and condensation phenomena in disordered urn models
Jun-ichi Inoue,Jun Ohkubo
Physics , 2006,
Abstract: We investigate equilibrium statistical properties of urn models with disorder. Two urn models are proposed; one belongs to the Ehrenfest class, and the other corresponds to the Monkey class. These models are introduced from the view point of the power-law behavior and randomness; it is clarified that quenched random parameters play an important role in generating power-law behavior. We evaluate the occupation probability $P(k)$ with which an urn has $k$ balls by using the concept of statistical physics of disordered systems. In the disordered urn model belonging to the Monkey class, we find that above critical density $\rho_\mathrm{c}$ for a given temperature, condensation phenomenon occurs and the occupation probability changes its scaling behavior from an exponential-law to a heavy tailed power-law in large $k$ regime. We also discuss an interpretation of our results for explaining of macro-economy, in particular, emergence of wealth differentials.
Ionic Liquid as Useful Media for Dissolution, Derivatization, and Nanomaterial Processing of Chitin  [PDF]
Jun-Ichi Kadokawa
Green and Sustainable Chemistry (GSC) , 2013, DOI: 10.4236/gsc.2013.32A003

This paper reviews studies on dissolution, derivatization, and nanomaterial processing of chitin using an ionic liquid as useful media. Because chitin is the second most abundant polysaccharide on the earth after cellulose, there is major interest in conversion of native chitin resources into various useful materials after proper dissolution in suitable solvents. For the derivatization and nanomaterial processing of chitin, the author has been focusing on ionic liquids because which have been found to be used as good solvents for cellulose in a past decade. The author found that an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), dissolved chitin in concentrations up to 4.8 wt% and mixtures of the higher amounts of chitin with AMIMBr gave ion gels. Acetylation, the simplest derivatization, of chitin using acetic anhydride was achieved in the AMIMBr solvent under mild conditions. Furthermore, the chitin nanofibers were fabricated by regeneration technique from the chitin ion gel with AMIMBr using methanol. Moreover, filtration of the chitin nanofiber dispersion with methanol was carried out to give a chitin nanofiber film. The chitin nanofiber-poly(vinyl alcohol) composite film was also prepared from the ion gel by co-regeneration method.

Thyroid gland cutaneous fistula secondary to a migratory fish bone: a case report
Toyoaki Ohbuchi, Takahisa Tabata, Khac-Hung Nguyen, Jun-ichi Ohkubo, Akiko Katoh, Hideaki Suzuki
Journal of Medical Case Reports , 2012, DOI: 10.1186/1752-1947-6-140
Abstract: A 56-year-old Japanese woman presented with a two-month history of a painless cutaneous fistula in her anterior neck with pus discharge. Endoscopic examinations showed no abnormality, but computed tomography revealed a bone-density needle-shaped foreign body sticking out anteroinferior from the esophagus wall, penetrating through her left thyroid lobe and extending nearly to the anterior cervical skin. A migratory fish bone was suspected, and the foreign body was removed under general anesthetic, combined with a hemithyroidectomy. The injured esophageal mucosa was sutured and closed. Our patient’s postoperative course was uneventful, and she was allowed oral food intake seven days after the surgery. No evidence of recurrence was seen over the postoperative follow-up period of 42?weeks.We should be aware that fish bone foreign bodies may migrate out of the upper digestive tract and lodge in the thyroid gland.
Helium and Argon Isotopic Studies of Fossil Material and the Theoretical Evolution of He and Ar in Earth’s Atmosphere through Time  [PDF]
Yuko Arakawa, Jun-Ichi Matsuda
International Journal of Geosciences (IJG) , 2012, DOI: 10.4236/ijg.2012.325091
Abstract: We analyzed the elemental concentrations and the isotopic compositions of helium and argon in Cambrian to Jurrassic aged Gastropod, Ammonite and Trilobite fossils in order to examine variation in these gases through time. Fossil samples yielded He and Ar isotopic ratios close to the present day atmospheric values, but also indicated some addition of a radiogenic component. We compared the results to theoretical values calculated from a mathematical model of Earth’s atmosphere assuming mantle degassing. Results from our mathmatical models showed that the 40Ar/36Ar ratio of Earth’s atmosphere increased rapidly after the formation of the Earth, but has been almost identical to the present day value for the last 1 Ga. For atmospheric helium, model results were consistent with present day atmospheric values, assuming complete helium degassing from the continental crust into the atmosphere. The model suggests that the atmospheric 3He/4He ratio has remained relatively constant for the last 0.1 Ga. Given the similarity between present day and ancient He and Ar isotopic ratios, we conclude that the corresponding ratios measured in ancient fossil material may partially reflect composition of the ancient atmosphere and are not necessarily due to contamination by the present day atmosphere.
Sequential Stimulus Pairing Procedure for the Students with Intellectual Disabilities  [PDF]
Mikimasa Omori, Jun-ichi Yamamoto
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.43A036

For most of students with autism spectrum disorders (ASD) and Williams syndrome (WS), a rare genetic neurodevelopmental disorder, are known to have intellectual disabilities (ID). Students with ID often show the difficulties in reading. Especially, they are difficult to acquire the equivalence relations among pictures, written letters, and sounds and to have fluent eye movement during reading. Previous research suggested that a student with autism acquired Kanji reading skills by using stimulus pairing training. However, for acquiring word reading skills, new training which facilitates the fluent eye movement is necessary and we developed sequential stimulus pairing training. In the present study, we examined the acquisition of word reading skills through sequential stimulus pairing training for three students with ID who were also diagnosed as WS and three students with ID who were not diagnosed with WS. In a trial, each letters, the word, spoken sound, and picture were presented sequentially. With 6 students, result indicated that they could acquire the word reading skills, and also showed the improvement of their eye movement in reading. The result suggested sequential stimulus pairing training is effective to acquire both equivalence relations and fluent eye movement for wide range of students with ID.

Biharmonic curves in Minkowski -space
Jun-Ichi Inoguchi
International Journal of Mathematics and Mathematical Sciences , 2003, DOI: 10.1155/s016117120320805x
Abstract: We give a differential geometric interpretation for the classification of biharmonic curves in semi-Euclidean 3-space due to Chen and Ishikawa (1991).
Biharmonic curves in Minkowski -space. Part II
Jun-Ichi Inoguchi
International Journal of Mathematics and Mathematical Sciences , 2006, DOI: 10.1155/ijmms/2006/92349
Abstract: We give a differential geometric characterization for biharmonic curves with null principal normal in Minkowski 3-space.
Preparation and Applications of Amylose Supramolecules by Means of Phosphorylase-Catalyzed Enzymatic Polymerization
Jun-ichi Kadokawa
Polymers , 2012, DOI: 10.3390/polym4010116
Abstract: This paper reviews preparation and applications of amylose supramolecules by means of phosphorylase-catalyzed enzymatic polymerization. When the enzymatic polymerization of α-d-glucose 1-phosphate (G-1-P) as a monomer was carried out in the presence of poly(tetrahydrofuran) (PTHF) of a hydrophobic polyether as a guest polymer, the supramolecule, i.e., an amylose-PTHF inclusion complex, was formed in the process of polymerization. Because the representation of propagation in the polymerization is similar to the way that vines of plants grow twining around rods, this polymerization method for the preparation of amylose-polymer inclusion complexes was proposed to be named “vine-twining polymerization”. Various hydrophobic polyethers, polyesters, poly(ester-ether), and polycarbonates were also employed as the guest polymer in the vine-twining polymerization to produce the corresponding inclusion complexes. To obtain the inclusion complex from a strongly hydrophobic guest polymer, the parallel enzymatic polymerization system was developed as an advanced extension of the vine-twining polymerization. In addition, it was found that amylose selectively includes one side of the guest polymer from a mixture of two resemblant guest polymers, as well as a specific range in molecular weights of the guest PTHF. Amylose also exhibited selective inclusion behavior toward stereoisomers of poly(lactide)s. Moreover, the preparation of hydrogels through the formation of inclusion complexes of amylose in vine-twining polymerization was achieved.
Quantitative trait locus mapping of genes that control body length and plasma insulin-like growth factor 1 level in mice
Jun-ichi Suto
BMC Research Notes , 2012, DOI: 10.1186/1756-0500-5-547
Abstract: Correlations between body length and IGF1 levels were statistically significant in F2 populations. For body length, two significant QTLs were identified on chromosomes 15 and 17. For IGF1 levels, three significant QTLs were identified on chromosomes 10, 12, and 19. QTLs on chromosomes 12 and 19 appeared to be novel, and the latter interacted with the Ay allele.QTLs for body length and IGF1 levels contained candidate genes that were components of the growth hormone/insulin-like growth factor axis. However, there was no overlap between QTLs for these two traits. Contrary to our expectations, QTLs that interacted with the Ay allele were identified not for body length but for IGF1 levels. Body length and IGF1 levels were, thus, controlled by different sets of genes.Traditionally, five single gene obesity mutations, Cpefat, Tubtub, Lepob, Leprdb, and Ay, have been identified in mice [1]. Among the five mutations, only the Ay allele is dominant and homozygous lethal; therefore, living Ay mice are invariably heterozygotes. Obesity in Ay mice is moderate and occurs late compared with that in the other four mutants. The Ay allele is known not only to cause obesity but also to promote linear growth [2].In normal mice, the agouti gene is expressed only in the skin [3,4], and it regulates pigmentation by serving as an inverse agonist of the melanocortin 1 receptor [5,6]. However, in Ay mice, the Ay allele is associated with a large deletion, causing agouti gene expression to be aberrantly controlled by the unrelated Raly gene promoter and leading to its ectopic overexpression [4,7-9]. As a result, Ay mice have a yellow coat color and develop maturity onset obesity. Obesity in Ay mice is believed to be a consequence of the agouti protein serving as a constitutive antagonist of the melanocortin 3 receptor (MC3R) and melanocortin 4 receptor (MC4R) by mimicking the action of the agouti-related protein [10-12].Two mouse strains congenic for the Ay allele are available to date: B6.Cg
Y chromosome of the inbred mouse KK/Ta strain is associated with reduced body size in Y-consomic strains
Jun-ichi Suto
BMC Research Notes , 2013, DOI: 10.1186/1756-0500-6-64
Abstract: Findings: In the DH-Chr Y-+/+ background, Y chromosome substitution significantly decreased the body weight in DH-Chr YKK-+/+ and DH-Chr YSJL-+/+ strains, and the DH-Chr YKK-+/+ strain was the lightest among the 17 Y-consomic strains. In the DH-Chr Y-Dh/+ background (Dh/+ mice have skeletal malformations and are usually lighter than +/+ mice), although Y chromosome substitution did not significantly alter the body weight, the DH-Chr YKK-Dh/+ strain was the lightest among the 17 Y-consomic-Dh/+ strains. In the (B6.Cg-Ay x DH-Chr Y) F1-+/+ background, Y chromosome substitution significantly decreased the body weight and length in the (B6.Cg-Ay x DH-Chr YKK) F1 hybrids. In the (B6.Cg-Ay x DH-Chr Y) F1-Ay/+ background (Ay causes obesity and promotes linear growth), Y chromosome substitution significantly decreased body weight and length in the (B6.Cg-Ay x DH-Chr YKK) F1-Ay/+ hybrids.A body-size-reducing effect of the Y chromosome of the KK/Ta mouse strain was observed irrespective of genetic background. The effect was observed in the presence of Dh and Ay, the autosomal dominant mutations, both of which are known to have substantial effects on body size. These results suggest that there are Y-linked genes that control the body size in mice.
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