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Toho University is a university in Ōta, Tokyo, Japan. Wikipedia.

Deng T.-B.,Toho University
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

This paper presents a closed-form method for minimizing the weighted squared error of variable fractional-delay (VFD) of an all-pass VFD digital filter under an equality constraint on its normalized root-mean-squared (NRMS) error of variable frequency response (VFR). The main purpose is to reduce the squared VFD error as much as possible while keeping its NRMS VFR error exactly at a predetermined value. We first prove that the linearized VFR error of an all-pass VFD filter is almost the same as its linearized phase error, and then convert the equality-constrained weighted-least-squares (WLS) design into an unconstrained optimization problem through the minimization of a mixed error function that mixes the weighted squared VFD error and squared VFR error. To reduce the computational complexity, we derive a closed-form mixed error function by utilizing Taylor series expansions of trigonometric functions. Therefore, the error functions can be efficiently computed without discretizing the design parameters (frequency ω and VFD parameter ρ). The closed-form mixed error function not only reduces the computational complexity, but also speeds up the design process as well guarantees the optimality of the final solution. Furthermore, a two-point search (dichotomous search) scheme is proposed for finding the optimal range ρ ∈ [ρMin, ρMax] of the VFD parameter ρ, and then the subfilter orders are optimized under a given filter complexity constraint (the number of all-pass VFD filter coefficients). This two-stage optimization process utilizes the NRMS VFD error as an error criterion. Design examples and comparisons are given to demonstrate that the closed-form mixed WLS method yields low-complexity all-pass VFD filters with a high-accuracy VFD response but without noticeably degrading its frequency response. © 2011 IEEE. Source

Deng T.-B.,Toho University
IEEE Transactions on Circuits and Systems I: Regular Papers | Year: 2011

This paper presents a simple linear programming (LP) technique for designing high-accuracy low-complexity finite-impulse-response (FIR) variable fractional-delay (VFD) digital filters in the minimax error sense. The objective of the minimax design is to minimize the maximum absolute error of the variable frequency response (VFR) of an FIR VFD filter, which is a nonlinear problem and difficult to solve. This paper shows that the minimax design can be approximately decomposed into a pair of separate LP subproblems by decoupling the minimization of the real-part VFR error from that of the imaginary-part error. As a result, the original nonlinear minimax design problem can be easily solved by solving the two LP subproblems separately. To reduce the VFD filter complexity, we also propose a one-by-one increase scheme for optimizing the subfilter orders in the Farrow structure such that a given design specification (maximum absolute error of VFR) can be exactly satisfied. Both even-order and odd-order design examples are given to illustrate that the decoupling minimax method is not only simple, but also can achieve excellent high-accuracy low-complexity FIR VFD filters. © 2011 IEEE. Source

It remains to be determined experimentally whether increasing fitness is related to positive selection, while stationary fitness is related to neutral evolution. Long-term laboratory evolution in Escherichia coli was performed under conditions of thermal stress under defined laboratory conditions. The complete cell growth data showed common continuous fitness recovery to every 2°C or 4°C stepwise temperature upshift, finally resulting in an evolved E. coli strain with an improved upper temperature limit as high as 45.9°C after 523 days of serial transfer, equivalent to 7,560 generations, in minimal medium. Two-phase fitness dynamics, a rapid growth recovery phase followed by a gradual increasing growth phase, was clearly observed at diverse temperatures throughout the entire evolutionary process. Whole-genome sequence analysis revealed the transition from positive to neutral in mutation fixation, accompanied with a considerable escalation of spontaneous substitution rate in the late fitness recovery phase. It suggested that continually increasing fitness not always resulted in the reduction of genetic diversity due to the sequential takeovers by fit mutants, but caused the accumulation of a considerable number of mutations that facilitated the neutral evolution. Source

Komatsu H.,Toho University
World Journal of Gastroenterology | Year: 2014

Hepatitis B (HB) virus (HBV) infection, which causes liver cirrhosis and hepatocellular carcinoma, is endemic worldwide. Hepatitis B vaccines became commercially available in the 1980s. The World Health Organization recommended the integration of the HB vaccine into the national immunisation programs in all countries. HBV prevention strategies are classified into three groups: (1) universal vaccination alone; (2) universal vaccination with screening of pregnant women plus HB immune globulin (HBIG) at birth; and (3) selective vaccination with screening of pregnant women plus HBIG at birth. Most low-income countries have adopted universal vaccine programs without screening of pregnant women. However, HB vaccines are not widely used in low-income countries. The Global Alliance for Vaccine and Immunization was launched in 2000, and by 2012, the global coverage of a three-dose HB vaccine had increased to 79%. The next challenges are to further increase the coverage rate, close the gap between recommendations and routine practices, approach high-risk individuals, screen and treat chronically infected individuals, and prevent breakthrough infections. To eradicate HBV infections, strenuous efforts are required to overcome socioeconomic barriers to the HB vaccine; this task is expected to take several decades to complete. © 2014 Baishideng Publishing Group Inc. All rights reserved. Source

Children and adults with pulmonary arterial hypertension (PAH) have similarities and differences in their background characteristics, hemodynamics, and clinical manifestations. Regarding genetic background, mutations in BMPR2- related pathways seem to be pivotal; however, it is likely that other modifier genes and bioactive mediators have roles in the various forms of PAH in children and adults. In pediatric PAH, there are no clear sex differences in incidence, age at onset, disease severity, or prognosis but, as compared with adults, syncope incidence, pulmonary vascular resistance, and mean pulmonary artery pressure are higher, and vasoreactivity to acute drug testing is more frequent, among children. Nevertheless, the pharmacokinetic effects of 3 major pulmonary vasodilators appear to be similar in children and adults with PAH. This review focuses on the specific pathophysiologic features of PAH in children. Source

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