Message encoding and decoding using an asynchronous chaotic laser diode transmitter-receiver array

We have numerically investigated a chaotic laser diode transmitter-receiver array scheme (CLDTRAS), which is a secure digital communication scheme using a difference between two types of transmitter-receiver array consisting of two self-pulsating laser diodes (LDs), i.e., a receiver LD and a transmitter LD. By analyzing the bit error rate, particularly its dependence on the parameter mismatches of the hardware and channel noise and on the correlation coefficient between a transmitter LD and receiver LD, we examined the problems of sensitivity to parameter mismatches and channel noise and a dependence on chaos synchronization between a transmitter LD and a receiver LD. The former makes communication difficult, and the latter makes it possible for an eavesdropper to estimate the receiver LD using chaos synchronization and to forge the hardware. Then we studied the effects of the bit error rate for various values of the threshold, which determines a binary message, and for various numbers of transmitters-receivers making up a LD transmitter-receiver array. It has been shown that a highly noise-tolerant and hardware-dependent communication scheme can be achieved with the LD transmitter-receiver array, whose transmitter and receiver LDs are asynchronous with respect to each other, by choosing the proper threshold and increasing the number of LD transmitters-receivers. Since it is possible to communicate without chaos synchronization, it becomes difficult to forge hardware and to eavesdrop with the forged hardware even if the key is stolen.     

Lattice dynamics of the Zn-Mg-Sc icosahedral quasicrystal and its Zn-Sc periodic 1/1 approximant

Quasicrystals are long-range-ordered materials that lack translational invariance, so the study of their physical properties remains a challenging problem. Here, we have carried out inelastic-X-ray- and neutron-scattering experiments on single-grain samples of the Zn-Mg-Sc icosahedral quasicrystal and of the Zn-Sc periodic cubic 1/1 approximant, with the aim of studying the respective influence of the local order and of the long-range order (periodic or quasiperiodic) on lattice dynamics. Besides the overall similarities and the existence of a pseudo-gap in the transverse dispersion relation, marked differences are observed, the pseudo-gap being larger and better defined in the approximant than in the quasicrystal. This can be qualitatively explained using the concept of a pseudo-Brillouin-zone in the quasicrystal. These results are compared with simulations on atomic models and using oscillating pair potentials, and the simulations reproduce in detail the experimental results. This paves the way for a detailed understanding of the physics of quasicrystals.     

Thickness dependence of structural and ferroelectric properties of sol-gel Pb(Zr0.56Ti0.44)0.90(Mg1/3Nb2/3)0.10O3 films

Sol-gel Pb(Zr_0.56Ti_0.44)_0.90(Mg_1/3Nb_2/3)_0.10O₃ (PZT-PMN) films were prepared onto the Ti/Pt/Ti bottom electrode by multilayer spin coating. The film thickness ranged from 0.22 to 0.88 μm. The Pt top electrodes were deposited on the PZT-PMN films by DC sputtering. The structural and ferroelectric properties of PZT-PMN films were investigated as a function of film thickness by X-ray diffraction (XRD), scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (XTEM), and by measuring the relative permittivity. The film retains the tetragonal perovskite structure with the [111] and [100] preferred orientations perpendicular to the film surface independent of film thickness. The [100] texture increases with increasing film thickness although the [111] texture is always predominant. The film consists of columnar grains. The average grain size is nearly independent of film thickness. The surface layer containing fine grains about 30 nm in diameter is induced on the top of the film. As the film thickness exceeds 0.44 μm, the number of the fine grains decreases remarkably. The crystalline interface layer about 10 nm thick is formed between the film and the bottom electrode. This interface layer is composed of Pt, Pb, Zr, Ti and O, while it is rich in Ti and deficient in Pb and O as compared with the inside of the film. The measured relative permittivity of the film increases with increasing film thickness, following the low permittivity interface model. On the basis of this model, the relative permittivity is estimated to be 3200 for the intrinsic PZT-PMN film, 750 for the surface layer and 50 for the interface layer.     

Induction of sensitivity to NK-mediated cytotoxicity by TNF-alpha treatment: possible role of ICAM-3 and CD44

The paper examines possibilities for employing more holistic approaches to the evaluation of health care programs. It is argued that the reductionism of conventional forms of economic evaluation, where value (or benefit) is seen in terms of either health consequences or individuals' utility, can cause a number of aspects of such programs to be overlooked. As such, this imposes fairly strict limits on the capacity of economic evaluation to inform public policy. In contrast, institutionalist economic theory in common with the community development approach to health promotion is an area of research which acknowledges that change to the broader socio-political environment can be a source of value. It is suggested that this idea has, for instance, significance for the evaluation of indigenous health programs where notions of "cultural appropriateness" have strong influence over the effectiveness and acceptability of such programs. It is concluded that no one evaluative approach is appropriate in all situations and that a greater receptiveness to broader sources of social value can help to improve the way evaluations are conducted.     

Early and late events in Fc epsilon RI signal transduction in human cultured mast cells

Protein tyrosine phosphorylation and other biochemical events have been shown to occur after cross-linking of Fc epsilonRI in rodent mast cells. To investigate the mechanism of Fc epsilonRI signal transduction in human mast cells, we used human cultured mast cells (HCMC) generated from cord blood cells in the presence of recombinant human stem cell factor and IL-6. We found that on cross-linking of Fc epsilonRI: 1) HCMC released histamine; 2) rapid tyrosine phosphorylation of multiple cellular substrates, including Syk, HS1, c-Cbl, ERK-1, and ERK-2, was observed; 3) intracellular Ca2+ and inositol phosphate production were increased within the first minute after Fc epsilonRI cross-linking; and 4) genistein, a tyrosine kinase inhibitor, inhibited both protein tyrosine phosphorylation and histamine release in a dose-dependent manner. These results were consistent with previous studies in rodent mast cells. In contrast, no tyrosine phosphorylation of phospholipase C gamma1 and Btk (Bruton's tyrosine kinase) were observed in our experimental conditions. These results suggest that the greater part of the early and late signaling events in HCMC is similar to those obtained with rodent mast cells and indicated that the requirement of tyrosine phosphorylation in the activation process of each of the signaling molecules might be different in HCMC and rodent mast cells. Our finding indicates that HCMC may be useful for analysis of Fc epsilonRI-mediated signal transduction in human mast cells.     

Effects of Iron Addition on the Microstructures and Mechanical Properties of Two-Phase Ni3Al-Ni3V Intermetallic Alloys

Metallurgical and Materials Transactions A - Microstructures and mechanical properties of dual two-phase Ni3Al (L12)-Ni3V (D022) intermetallic alloys to which iron (Fe) was added in different...     

The Role of Crystallographic Texture and Basal Plane Slip on Microstructurally Short Fatigue Crack Initiation and Propagation in Forged Billet and Rolled Bar Ti-6Al-4V Alloy

Tension-compression fatigue tests were conducted on forged (F-950) and rolled (R-950) Ti-6Al-4V alloys. The role of basal texture, produced by forging, was compared with prismatic texture, produced by rolling, on microstructurally short fatigue crack growth initiation and growth resistance. The fatigue life of R-950 alloy proved to be higher than that of F-950 alloy. Major differences in fatigue crack growth rate were detected in the short fatigue crack region at crack lengths of below 100 µm (F-950 alloy showing low resistance). To quantify the effect of texture alone, the opening/closure behaviour of a microstructurally small crack was analysed from the data obtained by combining an automatic in situ observation system with a digital image correlation technique. This analysis showed the crack opening stress of both alloys to be close to identical in the short fatigue crack growth region, nullifying the effect of crack closure. To study the effect of texture, cross-sectional electron backscatter diffraction analysis was performed at crack initiation sites. The results revealed that in F-950 alloy, short fatigue crack growth proceeded along basal planes that had similarly-oriented grains, whereas in R-950 alloy, short fatigue crack growth did not follow prismatic planes: the orientation varied.

     

Effects of temperature,initial stress intensity factor and loading speed on the crack branching in delayed failure

The relation between diffusion behavior of hydrogen atoms and crack branching in delayed failure was discussed.The hypotheses that diffusion paths of hydrogen atoms at crack tip broaden with increase of stress intensity factor $\text{K}$, and that crack branching occurs when hydrogen atoms diffuse through the position where stable cracks are to nucleate, can well explain the facts that crack branching occurs when $\text{K}$ reaches to a certain value, $\text{K}{}_{\mathrm{IB}}$, and that $\text{K}{}_{\mathrm{IB}}$ increases with increase of temperature. The initial stress intensity factor and loading speed do not actually influence $\text{K}{}_{\mathrm{IB}}$, which can also be explained by the above hypotheses.     

A compact programming environment for microprocessor-based controllers

To write a reliable program in an assembly language for microprocessor-based controller, we introduce data abstraction facility into an assembly language. For this purpose, we has designed and implemented ADT-RASM86 and its symbolic debugger. This paper presents the figure of the system and describes how the system is effective for writing a reliable program for microprocessors.     

Yield stress of a copper single crystal containing B2O3 particles

The yield stress of a copper single crystal containing vitreous B₂O₃ particles was measured as a function of temperature (77–1073 K) and strain rate (5.6 × 10^–6–5.6 × 10^–4sec^–1). Although the B₂O₃ particles in the copper matrix are a plastically non-deformable solid at low temperatures, they became liquid-like at high temperatures, above approximately 550 K. The yield stress of the Cu-B₂O₃ alloy at low temperatures was explained by the Orowan mechanism and the modulus-corrected yield stress of the Cu-B₂O₃ alloy at 1073 K was about four-fifths of the values at low temperatures. It was found that the liquid B₂O₃ particles could be the effective hardening centres even at high temperatures. At 873 and 1073 K, the yield stresses of the Cu-B₂O₃ alloy varied with the logarithm of the strain rates.