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991.
Here we introduce a model of parametrically coupled chaotic maps on a one-dimensional lattice. In this model, each element
has its internal self-regulatory dynamics, whereby at fixed intervals of time the nonlinearity parameter at each site is adjusted
by feedback from its past evolution. Additionally, the maps are coupled sequentially and unidirectionally, to their nearest
neighbor, through the difference of their parametric variations. Interestingly we find that this model asymptotically yields
clusters of superstable oscillators with different periods. We observe that the sizes of these oscillator clusters have a
power-law distribution. Moreover, we find that the transient dynamics gives rise to a 1/f power spectrum. All these characteristics indicate self-organization and emergent scaling behavior in this system. We also
interpret the power-law characteristics of the proposed system from an ecological point of view.
相似文献
992.
Nobuo Ueno Satoshi Kera Kazuyuki Sakamoto Koji. K. Okudaira 《Applied Physics A: Materials Science & Processing》2008,92(3):495-504
This article describes the origins of the width of the highest occupied molecular orbital (HOMO) state observed in the ultraviolet
photoemission spectra (UPS) of thin organic semiconductor films. Although much research has been performed on the electrical
properties of organic devices, a lot of crucial problems still remain. Among these problems, the charge mobility in organic
semiconductor systems is one the most important subjects to be elucidated. In order to discuss the mobility, it is essential
to understand both the intermolecular interaction and the electron-molecular vibration coupling. Experimental measurements
of the energy band dispersion give information about the intermolecular interaction, and experimental detection of the HOMO
hole-vibration coupling is indispensable to comprehend impacts of the electron-vibration coupling on the hole transport. Since
most of the information is hidden behind the finite bandwidth of the HOMO, only careful UPS measurements can provide information
on these important phenomena related to charge carrier dynamics. In this article, we summarize our recent challenges on UPS
measurements of organic thin films, which give the band dispersion of the HOMO and the HOMO hole-vibration coupling, and discuss
the origins of the UPS bandwidth that relates to the charge carrier dynamics. 相似文献
993.
Shingo Kanehira Kiyotaka Miura Kazuyuki Hirao Naoya Shibata Yuichi Ikuhara 《Applied Physics A: Materials Science & Processing》2008,92(4):913-916
We show a unique technique to form dense dislocations locally inside a MgO single crystal with a rock-salt type structure
using femtosecond (fs) laser irradiation. Cross-shaped patterns of micrometer size, originating from densely introduced dislocations,
are formed spontaneously around the focal point. We controlled the three-dimensional propagation of the dislocations by adjusting
the pulse energy of the fs laser and NA of objective lens. The technique may open up a new field of dislocation technology
for optical applications. 相似文献
994.
Huo Q Yuasa T Akatsuka T Takeda T Wu J Thet-Thet-Lwin Hyodo K Dilmanian FA 《Optics letters》2008,33(21):2494-2496
We propose a fluorescent x-ray computed tomography method using an array of detectors with an incident sheet beam, aimed at providing molecular imaging with high sensitivity and good spatial resolution. In this study, we prove the feasibility of this concept and investigate its imaging properties, including spatial and contrast resolutions and quantitativeness, by imaging an acrylic phantom and a normal mouse brain using a preliminary imaging system with monochromatic synchrotron x rays. 相似文献
995.
OPENCORE NMR: open-source core modules for implementing an integrated FPGA-based NMR spectrometer 总被引:1,自引:0,他引:1
Takeda K 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,192(2):218-229
A tool kit for implementing an integrated FPGA-based NMR spectrometer [K. Takeda, A highly integrated FPGA-based nuclear magnetic resonance spectrometer, Rev. Sci. Instrum. 78 (2007) 033103], referred to as the OPENCORE NMR spectrometer, is open to public. The system is composed of an FPGA chip and several peripheral boards for USB communication, direct-digital synthesis (DDS), RF transmission, signal acquisition, etc. Inside the FPGA chip have been implemented a number of digital modules including three pulse programmers, the digital part of DDS, a digital quadrature demodulator, dual digital low-pass filters, and a PC interface. These FPGA core modules are written in VHDL, and their source codes are available on our website. This work aims at providing sufficient information with which one can, given some facility in circuit board manufacturing, reproduce the OPENCORE NMR spectrometer presented here. Also, the users are encouraged to modify the design of spectrometer according to their own specific needs. A home-built NMR spectrometer can serve complementary roles to a sophisticated commercial spectrometer, should one comes across such new ideas that require heavy modification to hardware inside the spectrometer. This work can lower the barrier of building a handmade NMR spectrometer in the laboratory, and promote novel and exciting NMR experiments. 相似文献
996.
A modularly-structured neural network model is considered. Each module, which we call a ‘cell’, consists of two parts: a Hopfield neural network model and a multilayered perceptron. An array of such cells is used to simulate the Rule 110 cellular automaton with high accuracy even when all the units of neural networks are replaced by stochastic binary ones. We also find that noise not only degrades but also facilitates computation if the outputs of multilayered perceptrons are below the threshold required to update the states of the cells, which is a stochastic resonance in computation. 相似文献
997.
Kazuyuki Horie 《Macromolecular Symposia》1994,80(1):353-358
Photochemical hole burning (PHB) of free-base porphyrins in host polymers as a site-selective spectroscopy reveals the existence of vibronic structure in a porphyrin Q-band peak and low-energy excitation modes of host polymers. A new mechanism of photon-gated PHB by two-color sensitization of photoreactive polymers with a zinc porphyrin is also presented. 相似文献
998.
Deuterium isotope effects on swelling kinetics and volume phase transition in typical polymer hydrogels (poly(N-isopropylacrylamide) and polyacrylamide gels) are discussed. Deuterium substitutions affect on the swelling kinetics and volume phase transition of the polymer hydrogels. The slower swelling kinetics of hydrogels in D2O than in H2O arises mainly from the high viscosity of the medium. The deuterium isotope effect on the swelling-shrinking curve of hydrogels would come from the different polymer-solvent interaction. The microenvironments of hydrogels studied by solvatochromic fluorescence probe are compared with the bulk state. The zipper-type hydrogen-bonding inter-polymer complexes (poly(acrylic acid)-polyacrylamide and poly(acrylic acid)-poly(N-acryloylglycineamide)) are also investigated and show the huge isotope effect on the phase separation temperature. 相似文献
999.
Optical Review - In this study, we present a new method for measuring the tilt of an image sensor to the lens. The assembly accuracy of the lens and image sensor units has a significant influence... 相似文献
1000.