715 research outputs found

    Pulsations of Pre-White Dwarfs with Hydrogen-dominated Atmospheres

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    We carried out a fully non-adiabatic analysis for nonradial oscillations of pre-white dwarfs evolved from the post-Asymptotic Giant Branch (AGB) with hydrogen-dominated envelopes. It is shown that nuclear reactions in the hydrogen burning-shell excite low-degree g-modes in the period range of about 40-200 s for the pre-white dwarf models with Teff=40,000 K - 300,000 K. It is also shown that the amount of hydrogen {has} a significant influence on the instability domain of such pre-white dwarfs in the Hertzsprung-Russel (H-R) diagram. Thus, the thickness of hydrogen-dominated envelopes may be well constrained by observing the presence of the g-mode oscillations.Comment: PASJ accepted, 7 pages, 6 figure

    Density Discontinuity of a Neutron Star and Gravitational Waves

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    We calculate quasi-normal f- and g-modes of a neutron star with density discontinuity, which may appear in a phase transition at extreme high density. We find that discontinuity will reflect largely on the f-mode, and that the g-mode could also be important for a less massive star.Comment: REVTeX,18 pages, 8 figure

    Analytical Study of Robustness of a Negative Feedback Oscillator by Multiparameter Sensitivity

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    BACKGROUND:One of the distinctive features of biological oscillators such as circadian clocks and cell cycles is robustness which is the ability to resume reliable operation in the face of different types of perturbations. In the previous study, we proposed multiparameter sensitivity (MPS) as an intelligible measure for robustness to fluctuations in kinetic parameters. Analytical solutions directly connect the mechanisms and kinetic parameters to dynamic properties such as period, amplitude and their associated MPSs. Although negative feedback loops are known as common structures to biological oscillators, the analytical solutions have not been presented for a general model of negative feedback oscillators.RESULTS:We present the analytical expressions for the period, amplitude and their associated MPSs for a general model of negative feedback oscillators. The analytical solutions are validated by comparing them with numerical solutions. The analytical solutions explicitly show how the dynamic properties depend on the kinetic parameters. The ratio of a threshold to the amplitude has a strong impact on the period MPS. As the ratio approaches to one, the MPS increases, indicating that the period becomes more sensitive to changes in kinetic parameters. We present the first mathematical proof that the distributed time-delay mechanism contributes to making the oscillation period robust to parameter fluctuations. The MPS decreases with an increase in the feedback loop length (i.e., the number of molecular species constituting the feedback loop).CONCLUSIONS:Since a general model of negative feedback oscillators was employed, the results shown in this paper are expected to be true for many of biological oscillators. This study strongly supports that the hypothesis that phosphorylations of clock proteins contribute to the robustness of circadian rhythms. The analytical solutions give synthetic biologists some clues to design gene oscillators with robust and desired period

    Considering Corporate Strategies with Self-Organizing Patent Maps and Decision Making with AHP

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    Previously, we proposed an approach for corporate decision making with self-organizing patent maps labeled by technical terms and AHP. First, we extracted keywords by text mining to transform patent documents into feature vectors of the companies. Second, we inputted the feature matrix of technical terms and company names into self-organizing maps to create patent maps labeled by the technical terms. Then, we considered several corporate strategies utilizing the patent maps and made a decision with AHP. We applied our approach to two patent areas (information home appliance and 3D image) to show examples of corporate decision making. However, it was unclear how to derive corporate strategies in our previous work. In this paper, we propose an approach for considering corporate strategies with self-organizing patent maps labeled by technical terms. Then, we applied our approach to two other patent areas (mobile phone and organic electro-luminescence display) to show examples of considering corporate strategies and decision making with AHP

    High-density and low-roughness anodic oxide formed on SiC in highly concentrated LiCl aqueous solution

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    The wide bandgap and high carrier mobility of silicon carbide (SiC), as well as its physical and chemical stability, make it a promising material for a number of applications. One of the key requirements for these applications involves oxide formation on SiC. The usefulness of the oxide produced by anodizing is, however, limited since the anodic oxide formed on SiC in the usual dilute aqueous solution has a low density and high surface roughness. Here, we consider a new parameter in anodic oxide formation by focusing on the concentration of free water in the electrolyte, using a highly concentrated aqueous solution. In a concentrated solution, oxygen evolution, which results in a reduction in the density of the oxide, is suppressed, and the rate of formation of anodic oxide at defect sites effectively decreases to reduce the surface roughness. Furthermore, an interfacial layer with a higher density than SiO₂ is formed between SiC and SiO₂, buffering the difference in density between them. As a result, we successfully obtained an anodic oxide with a relatively high density and low surface roughness. This study provides a new approach to improving the properties of the anodic oxide formed on SiC

    Fast square-area detection algorithm using automata for VLSI implementation

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    金沢大学大学院自然科学研究科情報システム金沢大学工学部Conventional image sensors, including CCD sensors and smart sensors are considered for just acquiring the image as the matrix of dots, not for recognizing the meaning of image. In this paper, we propose a novel real-time algorithm to detect the square area in an object using the structure of node automata, and discuss its implementation as a CMOS image sensor, where the pixels and the node automata are integrated in one chip. We also discuss the search algorithm of their position in the pixel plain using area dividing methodology

    Homologous p35 proteins of baculoviruses show distinctive anti-apoptotic activities which correlate with the apoptosis-inducing activity of each virus1The last author, Professor Maeda, has passed away after the acceptance of the paper. The rest of the authors would like this paper to be a memorial to him.1

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    AbstractThe anti-apoptotic activity of p35s from two baculoviruses, Autographa californica nucleopolyhedrovirus (AcNPV) and Bombyx mori NPV (BmNPV), was compared in mammalian cells. AcNPV p35 efficiently blocked apoptosis induced by caspase overexpression, but BmNPV p35 did so very poorly. Analysis of chimeric p35s and in vitro cleavage of wild type p35s suggest that the cleavage efficiency of p35 correlates with the blocking activity. Single amino acid substitutions of BmNPV p35 with those observed in AcNPV p35, however, resulted in significant loss of its anti-apoptotic activity. We speculate that sequences flanking the cleavage site have uniquely evolved during baculovirus evolution

    Development of an accurate kinetic model for the central carbon metabolism of Escherichia coli

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    Additional file 2. Comparison of our kinetic model with other existing models

    CADLIVE Optimizer: Web-based Parameter Estimation for Dynamic Models

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    Computer simulation has been an important technique to capture the dynamics of biochemical networks. In most networks, however, few kinetic parameters have been measured in vivo because of experimental complexity. We develop a kinetic parameter estimation system, named the CADLIVE Optimizer, which comprises genetic algorithms-based solvers with a graphical user interface. This optimizer is integrated into the CADLIVE Dynamic Simulator to attain efficient simulation for dynamic models

    Microvasculature of Normal and Hydropic Labyrinth

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    The microvasculature of the inner ear in guinea pigs and humans was observed with a scanning electron microscope using corrosion casting method. Alterations in the inner ear vasculature which occurred in association with experimental endolymphatic hydrops were also investigated. The results thus obtained are summarized as follows: 1. In the cochlea and vestibule, the arteries, coiled arterioles, and the veins are endowed with their respective characteristic morphologic features and play a role in the regulatory mechanisms of circulation. 2. The point in humans which is most different from guinea pigs was that coiled arterioles in the cochlea and the coil-like traveling of the anterior vestibular artery is not outstanding. 3. Arteriovenous anastomoses were demonstrated to exist in lateral wall of cochlea and utricular macula, a finding suggesting the existence of a regulatory mechanism for local blood flow. 4. Endolymphatic hydrops was noted to be preferentially associated with vascular abnormalities in the lateral wall of the cochlear duct and in the saccular macula, among other vestibular structures
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