Vocalization control in Mongolian gerbils (Meriones unguiculatus) during locomotion behavior

The vocalization behavior of Mongolian gerbils, a model animal of auditory physiology, was examined. A pair of gerbils was placed in a chamber, and their species-specific vocalizations and locomotive behaviors were recorded and analyzed. Two types of calls were predominantly produced: high-frequency upward frequency-modulated (HU-FM) calls and low-frequency multi-harmonic frequency-modulated (LM-FM) calls. Emission rates of HU-FM calls significantly decreased as the distance between the two gerbils increased, and playback of simulated HU-FM calls increased the emission rates. Acoustic analysis of HU-FM calls showed that the calls exhibited a stereotypic spectro-temporal structure including a fixed inter-onset interval (100-175 ms) and that individual differences in the frequency could convey the body size of the callers. The timing of HU-FM calls was highly synchronized with jump movements when an animal vocalized while jumping, suggesting the existence of tight locomotor-vocal coupling. Conversely, LM-FM calls were observed only when the gerbils tactilely contacted with each other while fighting over a food. These results suggest that Mongolian gerbils change the rates of call emissions and call types (e.g., LM-FM or HU-FM calls) in response to changes in visual and possibly tactile and auditory information. The functions of both calls are discussed in terms of their acoustic structures.     

Broadband waveguide intersections with low cross talk in photonic crystal circuits

We propose a new mechanism for constructing waveguide intersections with broad bandwidth and low cross talk in photonic crystal (PC) circuits. The intersections are created by combination of coupled-cavity wave-guides (CCWs) with conventional line-defect waveguides. This mechanism utilizes the strong dependence of the defect coupling on the field pattern in the defects and the alignment of the defects (i.e., the coupling angle) in CCWs. By properly designing the defect mode, we demonstrate through numerical simulation the establishment of such a waveguide intersection in one of the most useful PCs, which is based on a two-dimensional triangular lattice of air holes made in a dielectric material. The transmission of a 500-fs pulse at ~1.3 microm is simulated by use of the finite-difference time-domain method, showing negligible distortion and low cross talk.     

Triviality of Hierarchical Ising Model¶in Four Dimensions

Existence of critical renormalization group trajectory for a hierarchical Ising model in 4 dimensions is shown. After 70 iterations of renormalization group transformations, the critical Ising model is mapped into a vicinity of the Gaussian fixed point. Convergence of the subsequent trajectory to the Gaussian fixed point is shown by power decay of the effective coupling constant. The analysis in the strong coupling regime is computer-aided and Newman's inequalities on truncated correlations are used to give mathematical rigor to the numerical bounds. In order to obtain a criterion for convergence to the Gaussian fixed point, characteristic functions and Newman's inequalities are systematically used. Received: 27 April 2000 / Accepted: 5 January 2001     

自然循环回路内芯片的强化沸腾换热研究

针对电子器件的高效冷却问题,对自然循环回路系统内表面加工有方柱形微结构的硅片上FC-72的强化沸腾换热性能进行了实验研究.测试了两个芯片,其表面上的方柱形微结构的边长均为30μm,但高度分别为60 μm和200 μm.沸腾介质的过冷度设为10 K、25 K和35 K.随着壁面过热度的增加,微结构表面芯片上的热流密度急剧增加且临界热流密度时芯片的表面温度低于芯片回路正常工作的临界上限温度85℃,这与其在池沸腾换热中的特点一样.但临界热流密度值与池沸腾情况相比有所降低.     

Molecular dynamics simulations of structural disordering and forming defects in a milling process for selenium

In our previous paper, structural changes of selenium powders ground by a planetary ball mill at various rotational speeds were investigated for the nanostructural modification of particles using mechanical grinding process. The experimental results indicated that the amorphisation of Se by grinding accompanies lattice strain, and the lattice strain arises from impact energy which is more than an energy related to intermolecular interaction. In this paper, molecular dynamics simulations of selenium have been carried out under compressing conditions of various pressure strengths for obtaining information of the lattice strain at atomic level. Then, dynamical behaviour of atomic configuration has been discussed in this process. The structural disordering and formation of the structural defects were estimated by deviations of bond length and angle and the number of created defects before and after compressing from simulated results. The disordering took place during compressing at various pressure strengths, and the disordered atoms return to their initial positions at lower pressure. Stable disordered state and defects after the compression can however remain by compression at more than a certain pressure strength mainly associated with binding energy of selenium.     

Nanoparticles in Emissions and Atmospheric Environment: Now and Future

Journal of Nanoparticle Research -     

Applying a Mode Selector to Improve the Pulse-Compression Performance of Asymmetric-Coupled-Waveguide-Based Dispersion Compensators

An InGaAsP slab-type asymmetric-coupled-waveguide-based dispersion compensator with a mode selector has been designed and fabricated. The mode selector is necessary to select either a symmetric [with a positive group-velocity dispersion (GVD)] or antisymmetric (with a negative GVD) supermode. These supermodes exist simultaneously in the dispersion-compensation region of the device. Pulse-compression experiments were used to test the dispersion compensator, evaluating the function of the mode selector. A theoretical study of the experimental results shows that the mode selector obtains a very strong selectivity (nearly 100%) for the antisymmetric supermode.     

Development of Non-Halogen Flame Retardant Optical Fiber and Optical Fiber Cord

A non-halogen highly flame-retardant 0.9mm optical fiber and 2.0mm simplex optical cord, which are harmonized with the ecosystem, have been developed. The characteristics of them are presented in this paper.     

Sharp photonic Crystal Defect Modes and Their Response to Ultrashort Optical Pulses

Single photonic crystal defects based on an air-bridge structure were fabricated. We obtained sharp defect modes with quality factors higher than 600 and observed their response to ultrashort optical pulses by utilizing two-photon absorption.