Expansion of Walsh Functions in Terms of Shifted Rademacher Functions and Its Applications to the Signal Processing and the Radiation of Electromagnetic Walsh Waves

The expressions for Walsh functions in terms of shifted Rademacher functions are applicable to the design of a directive and selective array antenna for Walsh waves which is capable of eliminating the interference caused by impulsive noises. They also are applicable to voice processing because of their shift-invariant property. The shifted Rademacher functions were previously introduced by shiftiAg horizontally the periodic Rademacher functions. It was shown that the Walsh functions could be expressed as a linear combination of a finite number of the shifted Rademacher functions. This paper develops the actual expansions of the Walsh functions in terms of the shifted Rademacher functions. The coefficients in this series take only the values of either + 1 or -1. The shifted Rademacher coefficients appearing in the expansion of a given function in tenns of shifted Rademacher functions have the advantage that the coefficients of a shifted function are available by shifting cyclically the original coefficients.     

Strong induction of phytochelatin synthesis by zinc in marine green alga, Dunaliella tertiolecta

Synthesis of phytochelatins (PCs), heavy-metal-sequestering peptides, in the marine green alga, Dunaliella tertiolecta, was evaluated under various conditions of exposure to heavy metals. To investigate the effect of heavy metals on both PC synthesis and their upstream biosynthetic reactions, an ion-pair-HPLC system was developed in this study, by which PCs and their biosynthetic intermediates, cysteine (Cys), gamma-glutamylcysteine (gammaEC) and glutathione (GSH), could be determined simultaneously with high sensitivity. When the cells were exposed to Zn2+, the level of PCs was maximal at 200 microM and significantly higher than that obtained after exposure to 400 microM Cd2+, which is the strongest inducer of PC synthesis in higher plants in vivo and in vitro as well as in microalgae. The predominant PC subtype was PC4, followed by PC3 and PC5, whereas PC2, which is generally abundant in higher plants, has the lowest level among PC2 to PC5. These results suggest that the characteristics of PC synthase in D. tertiolecta including the requirement of heavy metals for its catalysis and substrate specificity towards GSH and PC(n) are considerably different from those in higher plants and other algae. While PC synthesis proceeded in the heavy-metal-treated cells, the level of GSH did not appreciably change. To maintain the same size of the GSH pool, GSH must be newly synthesized to balance the amount consumed for PC synthesis.     

Architectures for ATM network survivability and their fielddeployment

Future networks must offer extremely high levels of reliability because information has become critical to the continued well-being of society. This article shows the approaches to the survivable ATM network. The reliability requirements of future networks are discussed first. Development results of three typical restoration architectures (automatic protection switch (APS), self-healing network (SHN), and failure-resistant virtual path (FRVP)) for ATM networks are then shown. Next, we describe current progress in standardization activities. They also discuss open issues that must be resolved in future studies     

Density and viscosity of linear perfluoropolyethers under high pressures

New experimental data on the density and viscosity of linear, unbranched perfluoropolyethers are presented at temperatures from 273 to 333 K and pressures up to 180 MPa. The measurements were carried out by a high-pressure burrette apparatus and a falling-cylinder viscometer. The uncertainties of the measurements are estimated to be less than 0.09% for the specific volume and 2.5% for the viscosity. The P-V data at each temperature are correlated satisfactorily by the Tait equation. The viscosity data are also analyzed and correlated with pressure or molar volume by several empirical and theoretical equations.     

A Simple Control Algorithm for Rearrangeable Switching Networks with Time Division Multiplexed Links

A simple control algorithm is proposed for a three-stage rearrangeable switching network with time division multiplexed links. The nonblocking condition is shown for the rearrangeable network controlled by the proposed algorithm. The rearrangeable nonblocking network controlled by the proposed method is more cost effective in hardware than a strictly nonblocking network for a large number of channels multiplexed on links. The computing complexity of the algorithms is not more than that for controlling the strictly nonblocking network. In the proposed algorithm, only one path must be moved in the rearrangement, thus reducing the difficulty in implementing the rearrangeable network. This algorithm is efficient for broadband switching systems or cross-connect devices where nonblocking switches are needed.     

A dynamic associative memory system by adopting an amygdala model

Although several kinds of computational associative memory models and emotion models have been proposed since the last century, the interaction between memory and emotion is almost always neglected in these conventional models. This study constructs a dynamic memory system, named the amygdala-hippocampus model, which intends to realize dynamic auto-association and the mutual association of time-series patterns more naturally by adopting an emotional factor, i.e., the functional model of the amygdala given by Morén and Balkenius. The output of the amygdala is designed to control the recollection state of multiple chaotic neural networks (MCNN) in CA3 of the hippocampus-neocortex model proposed in our early work. The efficiency of the proposed association system is verified by computer simulation using several benchmark time-series patterns. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Key factors in tissue engineering

Tissue engineering is an emerging biomedical form of engineering aiming at regeneration of natural tissues or creation of biological substitutes for defective or lost tissues and organs using cells of different species. It is essential for the tissue self-regeneration, for instance, to provide a space necessary for regeneration with certain materials and technologies. This article overviews such key factors required for tissue engineering.     

Anisotropic in vitro vessel model using poly(vinyl alcohol) hydro gel and mesh material

In the present study, the authors fabricated straight multilayer hybrid tubular in vitro vessel models (inner diameter D_in = 10 mm; thickness T = 4 mm) composed of poly(vinyl alcohol) hydrogel (PVA‐H) and anisotropic mesh materials. The authors performed tensile, stress‐relaxation and cyclic‐tensile tests using axial and circumferential test pieces as well as pressure‐diameter (P‐D) tests using tubular test piece. In the tensile and stress‐relaxation tests, the anisotropic and nonlinear mechanical properties and hysteresis characteristic of the in vitro models were confirmed. The in vitro models also showed behavior qualitatively similar to that of native arteries in cycle‐tensile and P‐D tests. These results demonstrate that the mechanical properties of native vessels can be duplicated in an in vitro model by controlling the components of the mesh material, the orientation of elastic fibers in the mesh material, and the concentration and thickness of PVA‐H layers. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010