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Search Results: 1 - 10 of 281 matches for " Katsuaki Mishima "
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Nonlinear Dynamic Analysis of Vowels in Cleft Palate Children with or without Hypernasality
Katsuaki Mishima,Hiroyuki Nakano,Tatsushi Matsumura,Norifumi Moritani,Seiji Iida,Yoshiya Ueyama
International Journal of Otolaryngology , 2012, DOI: 10.1155/2012/739523
Abstract: Objectives. To clarify the difference between Lyapunov exponents (LEs) for cleft palate (CP) patients with hypernasality versus without hypernasality and to investigate the relationship between their LEs and nasalance scores (NSs). Material and Methods. Six CP patients with severe hypernasality (mean age 9.2 years) and six CP patients without hypernasality (mean age 8.0 years) were enrolled. Five Japanese vowels were recorded at 44.1 KHz, and the NSs were measured simultaneously. The mean first LE (mLE1) from all one-second intervals was computed. Results. The mLE1 for /o/ in patients with hypernasality was significantly higher than that in patients without hypernasality. The correlation coefficients between the mLE1 and NS for all vowels were not statistically different. Conclusion. The voice signal of /o/ for the patients with hypernasality was more instable than in those without hypernasality. The chaotic phenomenon was independent of nasal resonance in CP voice.
Nonlinear Dynamic Analysis of Vowels in Cleft Palate Children with or without Hypernasality
Katsuaki Mishima,Hiroyuki Nakano,Tatsushi Matsumura,Norifumi Moritani,Seiji Iida,Yoshiya Ueyama
International Journal of Otolaryngology , 2012, DOI: 10.1155/2012/739523
Abstract: Objectives. To clarify the difference between Lyapunov exponents (LEs) for cleft palate (CP) patients with hypernasality versus without hypernasality and to investigate the relationship between their LEs and nasalance scores (NSs). Material and Methods. Six CP patients with severe hypernasality (mean age 9.2 years) and six CP patients without hypernasality (mean age 8.0 years) were enrolled. Five Japanese vowels were recorded at 44.1?KHz, and the NSs were measured simultaneously. The mean first LE (mLE1) from all one-second intervals was computed. Results. The mLE1 for /o/ in patients with hypernasality was significantly higher than that in patients without hypernasality. The correlation coefficients between the mLE1 and NS for all vowels were not statistically different. Conclusion. The voice signal of /o/ for the patients with hypernasality was more instable than in those without hypernasality. The chaotic phenomenon was independent of nasal resonance in CP voice. 1. Introduction Patients with cleft palate often exhibit nasality, which is a distinctive feature and an important target in speech therapy and rehabilitation. To evaluate velopharyngeal function, the aerodynamic and acoustic aspects of nasalization have been studied. An aerodynamic exam can diagnose the degree of velopharyngeal closure [1, 2], and acoustic measurements can categorize velopharyngeal insufficiency [3, 4]. The abnormal resonance generated by velopharyngeal insufficiency can be evaluated quantitatively using a nasometer [5]. On the other hand, the voice and speech of patients with cleft palates have been studied using many techniques including spectral analysis, perturbation analysis, and formant analysis. Zajac and Linville [6] and Lewis et al. [7] reported that cleft palate speakers have larger frequency perturbations (jitter) than normal controls. However, the methods used to calculate perturbations, jitter, and shimmer are only reliable for nearly periodic voice signals and cannot reliably analyze strongly aperiodic signals [8]. Recently, nonlinear dynamic methods have enabled the quantification of aperiodic and chaotic phenomena [9–11]. In our previous paper, we reported that the Lyapunov exponents (LEs) of the vowels /a/, /e/ and /o/ for adult cleft palate patients are higher than those for normal resonance adults and that there were no correlation coefficients between LEs and nasalance scores (NSs) [12]. These results suggested that vocal fold vibration may be less stable in adult cleft palate patients than in normal resonance subjects and that the LE may be a parameter
A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells: Multijunction Tandem, Lower Dimensional, Photonic Up/Down Conversion and Plasmonic Nanometallic Structures
Katsuaki Tanabe
Energies , 2009, DOI: 10.3390/en20300504
Abstract: Solar cells are a promising renewable, carbon-free electric energy resource to address the fossil fuel shortage and global warming. Energy conversion efficiencies around 40% have been recently achieved in laboratories using III-V semiconductor compounds as photovoltaic materials. This article reviews the efforts and accomplishments made for higher efficiency III-V semiconductor compound solar cells, specifically with multijunction tandem, lower-dimensional, photonic up/down conversion, and plasmonic metallic structures. Technological strategies for further performance improvement from the most efficient (Al)InGaP/(In)GaAs/Ge triple-junction cells including the search for 1.0 eV bandgap semiconductors are discussed. Lower-dimensional systems such as quantum well and dot structures are being intensively studied to realize multiple exciton generation and multiple photon absorption to break the conventional efficiency limit. Implementation of plasmonic metallic nanostructures manipulating photonic energy flow directions to enhance sunlight absorption in thin photovoltaic semiconductor materials is also emerging.
Tanabe, K. A Review of Ultrahigh Efficiency III-V Semiconductor Compound Solar Cells: Multijunction Tandem, Lower Dimensional, Photonic Up/Down Conversion and Plasmonic Nanometallic Structures. Energies, 2009, 2, 504-530.
Katsuaki Tanabe
Energies , 2009, DOI: 10.3390/en20300695
Abstract: I have stated in my recent review article that no direct observation of multiple exciton generation (MEG) in the shape of photocurrent extracted from a semiconductor had been made yet. [...]
Recent Developments in the PQCD Approach
Mishima, Satoshi
High Energy Physics - Phenomenology , 2007,
Abstract: We review recent developments in the perturbative QCD approach to exclusive hadronic B meson decays. We discuss the important next-to-leading-order corrections to B -> pi K, pi pi, and the penguin-dominated B -> PV modes, where P (V) is a pseudo-scalar (vector) meson.
Study of Penguin Pollution in the B^0 -> J/psi K_S Decay
Mishima, Satoshi
High Energy Physics - Phenomenology , 2007,
Abstract: We study the penguin pollution in the B^0 -> J/psi K_S decay up to leading power in 1/m_b and to next-to-leading order in \alpha_s, m_b being the b quark mass and \alpha_s the strong coupling constant. The deviation \Delta S_{J/psi K_S} of the mixing-induced CP asymmetry from sin(2\phi_1) and the direct CP asymmetry A_{J/psi K_S} are both found to be of O(10^{-3}) in a formalism that combines the QCD-improved factorization and perturbative QCD approaches.
B -> phi K decays in perturbative QCD approach
S. Mishima
Physics , 2001,
Abstract: We calculate the branching ratios and CP asymmetries of the $B\to \phi K$ decays using perturbative QCD approach, which includes $k_T$ and threshold resummations. Our results of branching ratios are consistent with the experimental data and larger than those obtained from the naive factorization assumption and the QCD-improved factorization approach.
Understanding the penguin amplitude in $B \to φK$ decays
S. Mishima
Physics , 2001, DOI: 10.1016/S0370-2693(01)01206-0
Abstract: We calculate branching ratios for pure penguin decay modes, $B\to \phi K$ decays using perturbative QCD approach. Our results of branching ratios are consistent with the experimental data and larger than those obtained from the naive factorization assumption and the QCD-improved factorization approach. This is due to a dynamical penguin enhancement in perturbative QCD approach.
Cattle traceability system in Japan for bovine spongiform encephalopathy
Katsuaki Sugiura,Takashi Onodera
Veterinaria Italiana , 2008,
Abstract: To promote consumer confidence in the safety of beef and to ensure the proper implementation of eradication measures against bovine spongiform encephalopathy (BSE), the Cattle Traceability Law was approved by the Diet in June 2003 and a cattle traceability system has been in operation in Japan since December 2003. The system enables tracing the cohort and offspring animals of a BSE case within 24 h of its detection. The traceability database system also provides distributors, restaurants and consumers with information on the cattle from which the beef that they sell, serve and consume originate.
Cluster Mass Estimate and a Cusp of the Mass Density Distribution in Clusters of Galaxies
Nobuyoshi Makino,Katsuaki Asano
Physics , 1998, DOI: 10.1086/306740
Abstract: We study density cusps in the center of clusters of galaxies to reconcile X-ray mass estimates with gravitational lensing masses. For various mass density models with cusps we compute X-ray surface brightness distribution, and fit them to observations to measure the range of parameters in the density models. The Einstein radii estimated from these density models are compared with Einstein radii derived from the observed arcs for Abell 2163, Abell 2218, and RX J1347.5-1145. The X-ray masses and lensing masses corresponding to these Einstein radii are also compared. While steeper cusps give smaller ratios of lensing mass to X-ray mass, the X-ray surface brightnesses estimated from flatter cusps are better fits to the observations. For Abell 2163 and Abell 2218, although the isothermal sphere with a finite core cannot produce giant arc images, a density model with a central cusp can produce a finite Einstein radius, which is smaller than the observed radii. We find that a total mass density profile which declines as $\sim r^{-1.4}$ produces the largest radius in models which are consistent with the X-ray surface brightness profile. As the result, the extremely large ratio of the lensing mass to the X-ray mass is improved from 2.2 to 1.4 for Abell 2163, and from 3 to 2.4 for Abell 2218. For RX J1347.5-1145, which is a cooling flow cluster, we cannot reduce the mass discrepancy.
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