Contrast Improvement Method for Monochrome Images Based on the Ratio of Local Variances of Gray levels

When the contrast of a captured image is not good, a method for contrast improvement may be useful. Especially, liner transform (LT) of gray levels and the histogram equalization (HE) method are well known as general methods. However, an effective contrast improvement does not always work, or an unnatural output is often generated by these methods. This paper proposes a method for contrast improvement to generate an image with medium contrast between those obtained by LT and HE. An input image is separated into an object area and a background area by every pixel. The variance of gray levels in the local area is used for measuring the local contrast. The ratio of the variances of gray levels in these areas is evaluated to determine the relative weights of LT and HE. The experimental results show that output images with higher contrast than that by LT and with less saturation of brightness and less noise than those by HE were generated by the proposed method. Copyright © 2008 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Luminosity monitor for the venus detector at TRISTAN

We constructed a luminosity monitor of the lead-scintillator sandwich type for the VENUS detector at the e⁺e⁻ collider TRISTAN. Photomultiplier tubes with transmissive mesh dynodes could be operated fairly well in a high magnetic field and hence the readout optics system was considerably simplified. We present the performance of the luminosity monitor for e⁺e⁻ collisions at √s = 50 and 52 GeV.     

Interfacial properties of polyelectrolyte–cellulose systems. III. Theoretical model for the electrokinetic behavior of cellulose fibers with adsorbed monolayers of cationic polyelectrolyte

A theoretical model is proposed to account for the experimental results in part II. The basic assumption is that the total surface charge of the monolayer-formed DP fibers stems from (i) fixed ionized groups on the surface and (ii) adsorbed ions on the surface from surrounding solutions. The fixed ionized groups are the carboxyl groups of the fibers and quaternary ammonium groups of the polymer. The proposed model correlates the amount of adsorbed polymer with the zeta potential of the monolayer-formed DP fibers. Calculations made on the proposed model using the experimental data in part II suggest that a comparison of the charge calculated from zeta potential with that from the amount of adsorbed polymer yields ca. 0.04% of the fixed ionizable groups as effective charged sites, i.e., electrokinetically detectable. This finding is due to the binding of counterions to the fixed ionized sites on the surface. Zeta potentials of the DP with adsorbed monolayers largely stem from the fixed ionized groups with only a minor contribution from the adsorbed ions. The zeta potentials are nearly proportional to the difference between the number of cationic and anionic groups on the surface.     

Starvation induces the formation of giant mitochondria in gastric parietal cells of guinea pigs

Mitochondria occasionally increase in size in response to metabolic injury. Numerous studies have reported giant mitochondria in patients with various diseases and animals with metabolic injuries, but there are few reports on giant mitochondria in normal cells under physiological conditions. Here, we report giant mitochondria in normal gastric parietal cells. Stomachs of guinea pigs fed freely, fasted or fasted and then injected with histamine were processed for electron microscopy. Giant mitochondria >2 microm in the diameter of their major axis were observed in resting-type parietal cells in the gastric glands of animals fasted for 60-72 h, whereas acid-secreting-type parietal cells found in those fed ad libitum did not contain giant mitochondria. Giant mitochondria showed unusual structures, especially in their cristae: they contained closely packed, tubular and concentric cristae as well as amorphous and pleomorphic inclusion bodies in their matrix. We observed giant mitochondria consisting of several segments, suggesting the fusion of several normal-sized mitochondria. Histamine injection decreased in a frequency of giant mitochondria in accordance with a decrease in a frequency of resting-type parietal cells. This is the first report of giant mitochondria in gastric parietal cells under physiological or near physiological conditions. Gastric parietal cells might be a good model for examining mitochondrial fusion and fission in a physiological state accompanied by the morphological change of the cells in the membrane system from an acid-secreting to resting type.     

Neuron-synapse IC chip-set for large-scale chaotic neural networks.

We propose a neuron-synapse integrated circuit (IC) chip-set for large-scale chaotic neural networks. We use switched-capacitor (SC) circuit techniques to implement a three-internal-state transiently-chaotic neural network model. The SC chaotic neuron chip faithfully reproduces complex chaotic dynamics in real numbers through continuous state variables of the analog circuitry. We can digitally control most of the model parameters by means of programmable capacitive arrays embedded in the SC chaotic neuron chip. Since the output of the neuron is transfered into a digital pulse according to the all-or-nothing property of an axon, we design a synapse chip with digital circuits. We propose a memory-based synapse circuit architecture to achieve a rapid calculation of a vast number of weighted summations. Both of the SC neuron and the digital synapse circuits have been fabricated as IC forms. We have tested these IC chips extensively, and confirmed the functions and performance of the chip-set. The proposed neuron-synapse IC chip-set makes it possible to construct a scalable and reconfigurable large-scale chaotic neural network with 10000 neurons and 10000/sup 2/ synaptic connections.     

Non-four-sided patch expressions with control points

This paper introduces new mathematical expressions which describe surface patches with three, five or six sides. Each side of a patch is given as a space curve expressed in Bézier type of second or third degree. Patch shape is modified predictably by moving its control points in the same way as with a four-sided patch. Distribution of cross tangent vectors along a patch boundary is also expressed in the same form with a few control vectors belonging to the boundary concerned. Therefore it can be connected with its surrounding four-sided patches smoothly. A general method of derivation of these equations is explained for further applications.     

Performance and effective kinetic models of methane steam reforming over Ni/YSZ anode of planar SOFC

Under mass/heat transfer and species diffusion limitations, the detailed thermodynamic investigations and experimental measurements were carried out to study and evaluate the performance of methane steam reforming and to develop its effective kinetic models over Ni/YSZ anode of the planar solid oxide fuel cell developed by Central Research Institute of Electric Power Industry (CRIEPI) of Japan. Based on the kinetic models of methane steam reforming developed by Xu and Froment, the effective kinetic models were developed. Combining the experiment data with the iteration calculation, the effective factor (C_e) is found to be 5.0 × 10^?4. Using these effective kinetic models, the detailed distributions of temperature, species, methane conversion, and carbon formation and gasification activity are presented under wide range of operating conditions. The results show that the local temperature in the reactor and the methane conversion are sensitive to the operating parameters. The region of the lowest local temperature and the most possible region of carbon formation are at the front of the porous anode sample. Due to the limitation of contact time, heat transfer and species diffusion, the methane conversion appreciably decreases with an increase of S/C ratio.     

Simulation of slow current transients and current collapse in GaN FETs

Two-dimensional transient simulations of GaN MESFETs are performed in which a three-level compensation model is adopted for a semi-insulating buffer layer, where a shallow donor, a deep donor and a deep acceptor are considered. When the drain voltage V _D is raised abruptly (while keeping the gate voltage V _G constant), the drain current I _D overshoots the steady-state value, and when V _D is lowered abruptly, I _D remains a low value for some periods, showing drain-lag behavior. These are explained by the deep donor’s electron capturing and electron emission processes. We also calculate a case when both V _D and V _G are changed abruptly from an off point, and quasi-pulsed I-V curves are derived from the transient characteristics. It is shown that the drain currents in the pulsed I-V curves are rather lower than those in the steady state, indicating that so-called current collapse could occur due to deep levels in the semi-insulating buffer layer. It is also shown that the current collapse is more pronounced when V _D is lowered from a higher voltage during turn-on, because the trapping effects become more significant.     

Antioxidant properties of herbal extracts selected from screening for potent scavenging activity against superoxide anions

BACKGROUND: In a previous study with the electron spin resonance (ESR) spin‐trapping method on large‐scale screening with ethanol extracts of approximately 1000 kinds of herbs, four herbal extracts with prominently potent ability to scavenge superoxide anions were chosen, namely the extracts from Punica granatum (peel), Syzygium aromaticum (bud), Mangifera indica (kernel) and Phyllanthus emblica (fruit)). In the present study, these extracts were further examined to determine if they also scavenge hydroxyl radicals, by applying the ESR spin‐trapping method, and if they have heat resistance as a desirable characteristic feature. RESULTS: Experiments with the Fenton reaction and UV irradiation of hydrogen peroxide, both of which generate hydroxyl radicals, showed that all four extracts had potent ability to directly scavenge hydroxyl radicals. Each extract exerted more potent hydroxyl radical‐scavenging activity than mannitol and salicylic acid. Furthermore, the scavenging activities against superoxide anions and hydroxyl radicals of the extracts of P. granatum (peel), M. indica (kernel) and P. emblica (fruit) proved to be heat‐resistant. CONCLUSION: The four herbal extracts chosen from extensive screening possess desirable antioxidant properties. In particular, three of them are expected to be suitable for food processing in which thermal devices are used, because of their heat resistance. Copyright © 2008 Society of Chemical Industry     

DNA sequence of the beta-isopropylmalate dehydrogenase gene and phylogenetic analysis of the yeast Saccharomyces exiguus Yp74L-3

The beta-isopropylmalate dehydrogenase (LEU2) gene from a homothallic wild-type yeast, Saccharomyces exiguus Yp74L-3, was analyzed to estimate the phylogenetic position of this strain in yeasts. The beta-isopropylmalate dehydrogenase gene of Yp74L-3 was first isolated as a clone complementing the leu2 mutation of Saccharomyces cerevisiae, and then confirmed to complement the haploid leu2 mutant derived from strain Yp74L-3 through genetic transformation. The nucleotide sequence of the cloned DNA revealed an open reading frame (ORF) encoding the beta-isopropylmalate dehydrogenase composed of 365 amino acids. The beta-isopropylmalate dehydrogenase coding sequence from the Yp74L-3 strain displayed 76.7% similarity to that of S. cerevisiae. Candidates for a UAS and a TATA-box in the 5'-upstream region and for a poly-A attachment site in the 3'-downstream region were found. A phylogenetic tree constructed from the nucleotide sequences of the beta-isopropylmalate dehydrogenase coding regions revealed that Yp74L-3 is located between S. cerevisiae and the Kluyveromyces yeasts. The LEU2 gene cloned from Yp74L-3 will serve as an effective genetic marker for constructing the transformation system in S. exiguus Yp74L-3.