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Search Results: 1 - 10 of 223 matches for " Seiichi Aiba "
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Biodegradability of Plastics
Yutaka Tokiwa,Buenaventurada P. Calabia,Charles U. Ugwu,Seiichi Aiba
International Journal of Molecular Sciences , 2009, DOI: 10.3390/ijms10093722
Abstract: Plastic is a broad name given to different polymers with high molecular weight, which can be degraded by various processes. However, considering their abundance in the environment and their specificity in attacking plastics, biodegradation of plastics by microorganisms and enzymes seems to be the most effective process. When plastics are used as substrates for microorganisms, evaluation of their biodegradability should not only be based on their chemical structure, but also on their physical properties (melting point, glass transition temperature, crystallinity, storage modulus etc.). In this review, microbial and enzymatic biodegradation of plastics and some factors that affect their biodegradability are discussed.
Design of RLS Wiener Smoother and Filter for Colored Observation Noise in Linear Discrete-Time Stochastic Systems  [PDF]
Seiichi Nakamori
Journal of Signal and Information Processing (JSIP) , 2012, DOI: 10.4236/jsip.2012.33041
Abstract: Almost estimators are designed for the white observation noise. In the estimation problems, rather than the white observation noise, there might be actual cases where the observation noise is modeled by the colored noise process. This paper examines to design a new estimation technique of recursive least-squares (RLS) Wiener fixed-point smoother and filter for colored observation noise in linear discrete-time wide-sense stationary stochastic systems. The observation y(k) is given as the sum of the signal z(k)=Hx(k) and the colored observation noise vc(k). The RLS Wiener estimators explicitly require the following information: 1) the system matrix for the state vector x(k); 2) the observation matrix H; 3) the variance of the state vector x(k); 4) the system matrix for the colored observation noise vc(k); 5) the variance of the colored observation noise; 6) the input noise variance in the state equation for the colored observation noise.
Supersymmetric Resolvent-Based Fourier Transform  [PDF]
Seiichi Kuwata
Journal of Modern Physics (JMP) , 2017, DOI: 10.4236/jmp.2017.81012
Abstract: We calculate in a numerically friendly way the Fourier transform of a non-integrable function, such as \"\", by replacing F with R-1FR, where R represents the resolvent for harmonic oscillator Hamiltonian. As contrasted with the non-analyticity of \"\"at \"\" in the case of a simple replacement of F by \"\", where \"\"and \"\" represent the momentum and position operators, respectively, the \"\"turns out to be an entire function. In calculating the resolvent kernel, the sampling theorem is of great use. The resolvent based Fourier transform can be made supersymmetric (SUSY), which not only makes manifest the usefulness of the even-odd decomposition of\"\"in a more natural way, but also leads to a natural definition of SUSY Fourier transform through the commutativity with the SUSY resolvent.
Absence of zero resonances of massless Dirac operators
Daisuke Aiba
Physics , 2014,
Abstract: We consider the massless Dirac operator $H=\alpha \cdot D+Q(x)$ on the Hilbert space $L^{2}(\mathbb{R}^{3},\mathbb{C}^{4})$, where $Q(x)$ is a $4\times4$ Hermitian matrix valued function which suitably decays at infinity. We show that the the zero resonance is absent for $H$, extending recent results of Sait\={o}-Umeda and Zhong-Gao.
Expression of CD133 and Extracellular Matrix Molecules in Malignant Brain Tumors  [PDF]
Seiichi Yoshida, Toshiro Koike
Neuroscience & Medicine (NM) , 2011, DOI: 10.4236/nm.2011.24052
Abstract: Background: CD133 could be characterized as a “stem-like” cell subpopulation and an invasive tumor phenotype. The objectives of this study were to investigate the relationship of CD133 and other remodeling factors such as matrix metalloproteinases (MMP) in the brain tumors. Methods: Tumors from 13 patients with brain tumors (8 lung cancer metastasis, 3 breast cancer metastasis, 2 gliomas) were studied to investigate the expression-patterns of CD133, EGFR, MT1-MMP, and MMP7 using the immunostaining and RT-PCR analysis. Results: EGFR immunostaining was detected in 75% (6/8) and 67% (1/3) of brain metastasis from lung adenocarcinoma and breast cancer, respectively. MT1-MMP immunostaining was also detected in 73% (8/11) of these brain metastasis. CD133 was not detected in these 13 patients. EGFR immunostaining was detected in 75% (6/8) and 67% (1/3) of brain metastasis from lung adenocarcinoma and breast cancer, respectively. MT1-MMP immunostaining was also detected in 73% (8/11) of these brain metastasis. CD133 was not detected in these 13 patients. Conclusions: The expression of CD133 indicates a marker for brain tumor initiating.
The Role of TL1A and DR3 in Autoimmune and Inflammatory Diseases
Yoshihiro Aiba,Minoru Nakamura
Mediators of Inflammation , 2013, DOI: 10.1155/2013/258164
Abstract: TNF-like ligand 1A (TL1A), which binds its cognate receptor DR3 and the decoy receptor DcR3, is an identified member of the TNF superfamily. TL1A exerts pleiotropic effects on cell proliferation, activation, and differentiation of immune cells, including helper T cells and regulatory T cells. TL1A and its two receptors expression is increased in both serum and inflamed tissues in autoimmune diseases such as inflammatory bowel disease (IBD), rheumatoid arthritis (RA), and ankylosing spondylitis (AS). Polymorphisms of the TNFSF15 gene that encodes TL1A are associated with the pathogenesis of irritable bowel syndrome, leprosy, and autoimmune diseases, including IBD, AS, and primary biliary cirrhosis (PBC). In mice, blocking of TL1A-DR3 interaction by either antagonistic antibodies or deletion of the DR3 gene attenuates the severity of multiple autoimmune diseases, whereas sustained TL1A expression on T cells or dendritic cells induces IL-13-dependent small intestinal inflammation. This suggests that modulation of TL1A-DR3 interaction may be a potential therapeutic target in several autoimmune diseases, including IBD, RA, AS, and PBC. 1. Characteristics of TL1A and DR3 1.1. TL1A TL1A, also referred to as vascular endothelial growth inhibitor (VEGI)-251, is a member of the tumor necrosis factor superfamily (TNFSF) of ligands, which was identified by Migone et al. in 2002 [1]. Although TL1A was identified as a longer variant of TL1/VEGI, the fourth exon of TL1A encodes the majority of TL1/VEGI, and it has been presumed that the original TL1/VEGI was a cloning artifact. TL1A exhibits approximately 20–30% homology to other TNFSF members [1]. Human TL1A consists of 251 amino acids: 35 in the cytoplasmic domain, 24 in the transmembrane region, and 192 in the extracellular domain. There are two potential N-linked glycosylation sites in the TL1A amino acid sequence, specifically Asn residues at amino acids 133 and 229 [1]. TL1A is a type II transmembrane protein. TL1A is initially expressed as a membrane-bound protein and is subsequently released as a soluble protein via ectodomain shedding by a metalloproteinase such as TNF-α converting enzyme (TACE) [2, 3]. TL1A expression is detected on human umbilical vein endothelial cells and synovial fibroblast-like cells and is upregulated by stimulation with proinflammatory cytokines such as TNF-α, IL-1, and PMA, a phorbol ester known to be a potent activator of protein kinase C [1, 4]. TL1A expression has also been confirmed on antigen-presenting cells and lymphocytes that are activated by Toll-like receptor (TLR)
A Model Study of the Strength Distribution for a Collective State Coupled with Chaotic Background System
H. Aiba,T. Suzuki
Physics , 1993,
Abstract: We consider a model in which a collective state couples to a large number of background states. The background states can be chosen to have properties which are classically characterized as regular or chaotic. We found that the dynamical nature of the background system considerably affects some fluctuation properties of the strength function. }
Scaling Analysis of Fluctuating Strength Function
Hirokazu Aiba,Masayuki Matsuo
Physics , 1999, DOI: 10.1103/PhysRevC.60.034307
Abstract: We propose a new method to analyze fluctuations in the strength function phenomena in highly excited nuclei. Extending the method of multifractal analysis to the cases where the strength fluctuations do not obey power scaling laws, we introduce a new measure of fluctuation, called the local scaling dimension, which characterizes scaling behavior of the strength fluctuation as a function of energy bin width subdividing the strength function. We discuss properties of the new measure by applying it to a model system which simulates the doorway damping mechanism of giant resonances. It is found that the local scaling dimension characterizes well fluctuations and their energy scales of fine structures in the strength function associated with the damped collective motions.
Nodal Domain Distribution for a Nonintegrable Two-Dimensional Anharmonic Oscillator
Hirokazu Aiba,Toru Suzuki
Physics , 2005, DOI: 10.1103/PhysRevE.72.066214
Abstract: We investigate the transition from integrable to chaotic dynamics in the quantum mechanical wave functions from the point of view of the nodal structure by employing a two dimensional quartic oscillator. We find that the number of nodal domains is drastically reduced as the dynamics of the system changes from integrable to nonintegrable, and then gradually increases as the system becomes chaotic. The number of nodal intersections with the classical boundary as a function of the level number shows a characteristic dependence on the dynamics of the system, too. We also calculate the area distribution of nodal domains and study the emergence of the power law behavior with the Fisher exponent in the chaotic limit.
A microscopic model of triangular arbitrage
Y. Aiba,N. Hatano
Physics , 2006, DOI: 10.1016/j.physa.2006.05.046
Abstract: We introduce a microscopic model which describes the dynamics of each dealer in multiple foreign exchange markets, taking account of the triangular arbitrage transaction. The model reproduces the interaction among the markets well. We explore the relation between the parameters of the present microscopic model and the spring constant of a macroscopic model that we proposed previously.
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