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排序方式: 共有332条查询结果,搜索用时 12 毫秒
321.
N Sanno A Teramoto M Sugiyama A Matsuno I Takumi S Tahara RY Osamura 《Canadian Metallurgical Quarterly》1998,50(1):11-17
Autonomic nervous activity is involved in the onset of paroxysmal atrial fibrillation, but it is not clear how the sympathetic and parasympathetic nervous systems interact before the onset of atrial fibrillation. Twelve lone atrial fibrillation patients and 10 healthy volunteers were studied using 24-hour Holter electrocardiography monitoring. A total of 17 episodes were analyzed. Autonomic nervous activity was assessed based on the high frequency power (HF) spectrum (HF represents parasympathetic nervous activity) and the ratio to the low frequency power (LF) spectrum (L/H represents sympathetic nervous activity) of heart rate variability during sinus rhythm, and the 24-hour averaged autonomic indices were compared between atrial fibrillation patients and healthy volunteers. Comparative data were obtained 30, 20, 10, and 2 min before the onset of atrial fibrillation for each episode. There were no significant differences in the HF and L/H ratio between the patients and healthy volunteers. There were no significant differences in the HF values before the onset of paroxysmal atrial fibrillation, but the L/H ratio before the onset of atrial fibrillation at 30, 20 and 10 min was 1.03 +/- 0.42, 0.95 +/- 0.50, and 1.32 +/- 0.46, respectively, and just before the episode was 1.73 +/- 0.73, so the Spearman's rank correlation coefficient was 0.43. Basal autonomic nervous activity in patients with paroxysmal atrial fibrillation showed no changes compared with healthy volunteers. Sympathetic nervous activity increased progressively from about 30 min before the onset of atrial fibrillation, but parasympathetic nervous activity showed no significant changes. Therefore, a transient augmentation of sympathetic tone may be important in the onset of atrial fibrillation. 相似文献
322.
Yoshiki Yamashita Masashi Kimura Masaru Kitahara Takumi Hamaguchi Masahiko Ohtaka 《Journal of Nuclear Science and Technology》2013,50(10):1256-1263
For ion radiation therapy, the measurement of effective atomic numbers, Zeff, is necessary to know the material distribution in a human body; the range of ions entering the human body is influenced by the material distribution along their paths. Zeff, however, cannot be measured at hospitals because monochromatic X-rays with different energies are necessary and are used only at synchrotron facilities. To make Zeff measurements at hand, we propose energy-resolved computed tomography (CT) using a “transXend detector”. By assigning two narrow energy ranges in the unfolding process of the data obtained by the transXend detector, Zeff for acrylic and aluminum can be estimated by energy-resolved CT. The estimated Zeff are compared with those obtained by dual-energy and monochromatic X-ray CT. 相似文献
323.
We show how gold recrystallizes when under the influence of electrochemical potentials. This "cold annealing" occurs without charge transfer reactions and preserves nanoscale structural features. By performing the process on plasmonic nanostructures, grain growth is monitored noninvasively by optical spectroscopy. In this way, the influence from crystal structure on plasmon resonances can be investigated independently. Observed spectral changes are in excellent agreement with analytical models and changes in electron relaxation time and plasma frequency are calculated. 相似文献
324.
Sannomiya T Scholder O Jefimovs K Hafner C Dahlin AB 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(12):1653-1663
Biosensing with nanoholes is one of the most promising applications of nanoplasmonic devices. The sensor properties, however, are complex due to coupled resonances through propagating and localized surface plasmons. This Full Paper demonstrates experimental and simulation studies on different plasmonic hole systems, namely various patterns of circular holes in gold films. In contrast to most previous work, here, the challenging situation of optically thin films is considered. The refractive-index-sensing properties, such as sensitive locations in the nanostructure and sensitive spectral features, are investigated. The multiple multipole program provides the complete field distribution in the nanostructure for different wavelengths. It is shown that the spectral feature most sensitive to refractive-index changes is the extinction minimum, rather than the maximum. The results are consistent with theory for perfect electrical conductors. The spectral response is investigated for molecular adsorption at different positions inside or outside a hole. Furthermore, the optical properties of nanohole arrays with long-range and short-range order are compared and found to demonstrate remarkable similarities. Our results help to predict the resonance wavelengths of nanoholes with arbitrary patterns, including short-range order. The results presented here are highly important since they extend and challenge several aspects of the current understanding of plasmon resonances in nanohole arrays. These theoretical models, simulation results, and experimental data together help provide the understanding necessary for the development of efficient biomolecular analysis tools based on metallic nanoholes. 相似文献
325.
Tetsuyuki Ishii Takumi Takashima Kenji Otani 《Progress in Photovoltaics: Research and Applications》2011,19(2):170-179
Various kinds of photovoltaic (PV) modules have been developed and practically operated as PV systems up to present. Investigation of the long‐term reliability of PV modules is indispensable for the use of PV systems as reliable energy sources. In this study, we show the results of outdoor exposure test in which the performance of 14 PV modules composed of five different kinds made by six different PV manufacturers have been measured since July 2004. The average performance is calculated in each year from 2005 to 2008, and the performance degradation is quantitatively evaluated. The results are that the magnitude of the performance degradation can be clearly classified by the kinds of the PV modules. The performance difference of the single‐crystalline silicon (sc‐Si) modules between 2005 and 2008 is from 1.9% to 2.8%. Polycrystalline silicon (pc‐Si) modules show performance degradation from 0.7% to 1.4%. The performance of an amorphous silicon/crystalline silicon (a‐Si:H/c‐Si) decreased by 0.7%. Although a pair of a‐Si modules had been already exposed to sunlight for about 6 months, the pair of modules show 4.4% of performance degradation. More than half of the performance degradation happened during the initial period from 2005 to 2006. This indicates that it takes about 2 years until the performance of a‐Si modules is stable. The performance is quite stable after 2006. Interestingly, the performance of the cupper indium gallium diselenide modules in 2008 is about 0.8% higher than that in 2005. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
326.
Katsuki Hayashi Kazuki Mitsui Tatsuki Shimizu Rikiya Kado Takumi Umada Akio Koike Satoshi Yoshida Seiji Inaba Akira Saitoh 《Journal of the American Ceramic Society》2023,106(3):1732-1738
The well-known Makishima–Mackenzie relationship, consisting of two terms of the dense packing structure and dissociation energy regarding bonding in constituent oxides, enables fabricating oxide glasses with ultrahigh Young's modulus (∼140 GPa) and a small coefficient of thermal expansion (CTE) (∼4 ppm/K). The effects of increasing MgO and Ta2O5 contents in an MgO–Ta2O5–Al2O3–SiO2–B2O3 glass system using a conventional melt-quenching method are revealed. The essential oxides of Al2O3 and Ta2O5 are primarily suitable for dense packing structures dominated by a large coordination number of oxygens. The substitution of CaO by MgO results in high dissociation energy when the glass composition falls in the peraluminous regime (Al2O3/[MgO + CaO] > 1). A small CTE is realized by increasing the molar ratio of Al2O3/MgO. According to magic-angle spinning-nuclear magnetic resonance spectra, mechanically and thermally functional oxide glasses depend on their structures. These findings facilitate the development of glass substrate applications without thermal dilatation. 相似文献
327.
Ruzzo [Tree-size bounded alternation, J. Comput. Syst. Sci. 21] introduced the notion of tree-size for alternating Turing machines (ATMs) and showed that it is a reasonable measure for classification of complexity classes. We establish in this paper that computations by tree-size and space simultaneously bounded ATMs roughly correspond to computations by time and space simultaneously bounded nondeterministic TMs (NTMs).We also show that not every polynomial time bounded and sublinear space simultaneously bounded NTM can be simulated by any deterministic TM with a slightly increased time bound and a slightly decreased space bound simultaneously. 相似文献
328.
Toshihiko Yamanishi Hirofumi Nakamura Yoshinori Kawamura Yasunori Iwai Kanetsugu Isobe Makoto Oyaidsu Masayuki Yamada Takumi Suzuki Takumi Hayashi 《Fusion Engineering and Design》2012,87(5-6):890-895
In JAEA, the tritium processing and handling technologies have been studied at TPL (Tritium Process Laboratory). The main R&D activities are: the tritium processing technology for the blanket recovery systems; the basic tritium behavior in confinement materials; and detritiation and decontamination. The R&D activities on tritium processing and handling technologies for a demonstration reactor (DEMO) are also planned to be carried out in the broader approach (BA) program by JAEA with Japanese universities. The ceramic proton conductor has been studied as a possible tritium processing method for the blanket system. The BIXS method has also been studied as a monitoring of tritium in the blanket system. The hydrogen transfer behavior from water to metal has been studied as a function of temperature. As for the behavior of high concentration tritium water, it was observed that the formation of the oxidized layer was prevented by the presence of tritium in water (0.23 GBq/cc). A new hydrophobic catalyst has been developed for the conversion of tritium to water. The catalyst could convert tritium to water at room temperature. A new Nafion membrane has also been developed by gamma ray irradiation to get the strong durability for tritium. 相似文献
329.
Takumi Kobayashi 《Machine Vision and Applications》2016,27(8):1175-1186
Local binary pattern (LBP) is widely used to extract image features as well as motion features in various visual recognition tasks. LBP is formulated in quite a simple form and thus enables us to extract effective features with a low computational cost. There, however, are some limitations mainly regarding sensitivity to noise and loss of image contrast information. In this paper, we propose a novel LBP-based feature extraction method to remedy those drawbacks without degrading the simplicity of the original LBP formulation. LBP is built upon encoding local pixel intensities into binary patterns which can be regarded as separating them into two modes (clusters). We introduce Fisher discriminant criterion to optimize the LBP coding for exploiting binary patterns more stably and discriminatively with robustness to noise. Besides, image contrast information is incorporated in a unified way by leveraging the discriminant score as a weight on the binary pattern; therefore, the prominent patterns, such as around edges, are emphasized. The proposed method is applicable to extract not only image features but also motion features by both efficiently decomposing a XYT volume patch into 2-D patches and employing the effective thresholding strategy based on the volume patch. In the experiments on various visual recognition tasks, the proposed method exhibits superior performance compared to the ordinary LBP and the other methods. 相似文献
330.
Akira?HaraEmail author Takumi?Ichimura Katsumi?Yoshida 《Journal of Intelligent Manufacturing》2005,16(6):645-661
Much of the research on extracting rules from a large amount of data has focused on the extraction of a general rule that
covers as many data as possible. In the field of health care, where people’s lives are at stake, it is necessary to diagnose
appropriately without overlooking the small number of patients who show different symptoms. Thus, the exceptional rules for
rare cases are also important. From such a viewpoint, multiple rules, each of which covers a part of the data, are needed
for covering all data. In this paper, we describe the extraction of such multiple rules, each of which is expressed by a tree
structural program. We consider a multi-agent approach to be effective for this purpose. Each agent has a rule that covers
a part of the data set, and multiple rules which cover all data are extracted by multi-agent cooperation. In order to realize
this approach, we propose a new method for rule extraction using Automatically Defined Groups (ADG). The ADG, which is based
on Genetic Programming, is an evolutionary optimization method of multi-agent systems. By using this method, we can acquire
both the number of necessary rules and the tree structural programs which represent these respective rules. We applied this
method to a database used in the machine learning field and showed its effectiveness. Moreover, we applied this method to
medical data and developed a diagnostic system for coronary heart diseases 相似文献