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Now showing items 1 - 16 of 128

  • Modeling head-related transfer functions with spherical wavelets

    Hu, Shichao   Trevino, Jorge   Salvador, César   Sakamoto, Shuichi   Suzuki, Yôiti  

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  • Area/Energy-Efficient Gammatone Filters Based on Stochastic Computation

    Onizawa, Naoya   Koshita, Shunsuke   Sakamoto, Shuichi   Abe, Masahide   Kawamata, Masayuki   Hanyu, Takahiro  

    This paper introduces area/energy-efficient gammatone filters based on stochastic computation. The gammatone filter well expresses the performance of human auditory peripheral mechanism and has a potential of improving advanced speech communications systems, especially hearing assisting devices and noise robust speech-recognition systems. Using stochastic computation, a power-and-area hungry multiplier used in a digital filter is replaced by a simple logic gate, leading to area-efficient hardware. However, a straightforward implementation of the stochastic gammatone filter suffers from significantly low accuracy in computation, which results in a low dynamic range (a ratio of the maximum to minimum magnitude) due to a small value of a filter gain. To improve the computation accuracy, gain-balancing techniques are presented that represent the original gain as the product of multiple larger gains introduced at the second-order sections. In addition, dynamic scaling techniques are proposed that scales up small values only on stochastic domain in order to reduce the number of stochastic bits required while maintaining the computation accuracy. For performance comparisons, the proposed stochastic gammatone filters are designed and evaluated on taiwan semiconductor manufacturing company (TSMC) 65-nm CMOS technology. As a result, the proposed filter achieves an area reduction of 90.7% and an energy reduction of 91.8% in comparison with a fixed-point gammatone filter at the same sampling frequency and a comparable dynamic range.
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  • A local representation of the head-related transfer function

    Hu, Shichao   Trevino, Jorge   Salvador, Cesar   Sakamoto, Shuichi   Li, Junfeng   Suzuki, Yoiti  

    Spatial descriptions of the head-related transfer function (HRTF) using spherical harmonics, which is commonly used for the purpose, consider all directions simultaneously. However, in perceptual studies, it is necessary to model HRTFs with different angular resolutions at different directions. To this end, an alternative spatial representation of the HRTF, based on local analysis functions, is introduced. The proposal is shown to have the potential to describe the local features of the HRTF. This is verified by comparing the reconstruction error achieved by the proposal to that of the spherical harmonic decomposition when reconstructing the HRTF inside a spherical cap. (C) 2016 Acoustical Society of America
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  • Residual Stress Analysis Based on Acoustic and Optical Methods

    Yoshida, Sanichiro   Sasaki, Tomohiro   Usui, Masaru   Sakamoto, Shuichi   Gurney, David   Park, Ik-Keun  

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  • Novel approaches for identification of anti-tumor drugs and new bioactive compounds

    Kawada, Manabu   Atsumi, Sonoko   Wada, Shun-ichi   Sakamoto, Shuichi  

    Thanks to the pioneering work done by Professor Hamao Umezawa, bioactive compounds have been used in treatment of several diseases including cancer. In this review, we discuss our work, which focuses on developing new candidates for anti-tumor drugs by screening for bioactive natural compounds in microbial cultures using unique experimental systems. We summarize our recent progress including the following: (1) small-molecule modulators of tumor-stromal cell interactions, (2) inhibitors of threedimensional spheroid formation of cancer cells, (3) multi-cancer cell panel screening and (4) new experimental animal models for cancer metastasis.
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  • Spatial accuracy of binaural synthesis from rigid spherical microphone array recordings

    Salvador, Cesar D.   Sakamoto, Shuichi   Trevino, Jorge   Suzuki, Yoiti  

    Binaural systems are a promising class of three-dimensional (3D) auditory displays for high-definition personal 3D audio devices. They properly synthesize the sound pressure signals at the ears of a listener, namely binaural signals, by means of the head-related transfer functions (HRTFs). Rigid spherical microphone arrays (RSMAs) are widely used to capture sound pressure fields for binaural presentation to multiple listeners. However, the spatial resolution needed in the RSMAs to allow for accurate binaural reproduction has not been studied in detail. The aim of this paper is to objectively address this question. We evaluated the spatial accuracy in binaural signals synthesized from the recordings of RSMAs with different number of microphones using the model of a human head. We find that the synthesis of spectral cues is accurate up to a maximum frequency determined by the number of microphones. Nevertheless, we also identify a limit beyond which adding more microphones does not improve overall accuracy. Said limit is higher for the interaural spectral cues than for the monaural ones.
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  • Study for Sound Absorbing Materials of Biomass Tubule etc

    SAKAMOTO, Shuichi   TAKAUCHI, Yuki   YANAGIMOTO, Kensaku   WATANABE, Seiji  

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  • Auditory Motion Information Drives Visual Motion Perception

    Hidaka, Souta   Teramoto, Wataru   Sugita, Yoichi   Manaka, Yuko   Sakamoto, Shuichi   Suzuki, Yoiti  

    Background: Vision provides the most salient information with regard to the stimulus motion. However, it has recently been demonstrated that static visual stimuli are perceived as moving laterally by alternating left-right sound sources. The underlying mechanism of this phenomenon remains unclear; it has not yet been determined whether auditory motion signals, rather than auditory positional signals, can directly contribute to visual motion perception. Methodology/Principal Findings: Static visual flashes were presented at retinal locations outside the fovea together with a lateral auditory motion provided by a virtual stereo noise source smoothly shifting in the horizontal plane. The flash appeared to move by means of the auditory motion when the spatiotemporal position of the flashes was in the middle of the auditory motion trajectory. Furthermore, the lateral auditory motion altered visual motion perception in a global motion display where different localized motion signals of multiple visual stimuli were combined to produce a coherent visual motion perception. Conclusions/Significance: These findings suggest there exist direct interactions between auditory and visual motion signals, and that there might be common neural substrates for auditory and visual motion processing.
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  • Fundamental study of acoustic leakage through a gap between gasket and flange surface

    SAKAMOTO, Shuichi   AZAMI, Takanari   NITTA, Isami   TSUKIYAMA, Yosuke  

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  • Regulation of Homologous Recombination by RNF20-Dependent H2B Ubiquitination

    Nakamura, Kyosuke   Kato, Akihiro   Kobayashi, Junya   Yanagihara, Hiromi   Sakamoto, Shuichi   Oliveira, Douglas V. N. P.   Shimada, Mikio   Tauchi, Hiroshi   Suzuki, Hidekazu   Tashiro, Satoshi   Zou, Lee   Komatsu, Kenshi  

    The E3 ubiquitin ligase RNF20 regulates chromatin structure by monoubiquitinating histone H2B in transcription. Here, we show that RNF20 is localized to double-stranded DNA breaks (DSBs) independently of H2AX and is required for the DSB-induced H2B ubiquitination. In addition, RNF20 is required for the methylation of H3K4 at DSBs and the recruitment of the chromatin-remodeling factor SNF2h. Depletion of RNF20, depletion of SNF2h, or expression of the H2B mutant lacking the ubiquitination site (K120R) compromises resection of DNA ends and recruitment of RAD51 and BRCA1. Consequently, cells lacking RNF20 or SNF2h and cells expressing H2B K120R exhibit pronounced defects in homologous recombination repair (HRR) and enhanced sensitivity to radiation. Finally, the function of RNF20 in HRR can be partially bypassed by forced chromatin relaxation. Thus, the RNF20-mediated H2B ubiquitination at DSBs plays a critical role in HRR through chromatin remodeling.
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  • Visual motion perception induced by sounds in vertical plane

    Teramoto, Wataru   Manaka, Yuko   Hidaka, Souta   Sugita, Yoichi   Miyauchi, Ryota   Sakamoto, Shuichi   Gyoba, Jiro   Iwaya, Yukio   Suzuki, Yoiti  

    The alternation of sounds in the left and right ears induces motion perception of a static visual stimulus (SIVM: Sound-Induced Visual Motion). In this case, binaural cues were of considerable benefit in perceiving locations and movements of the sounds. The present study investigated how a spectral cue - another important cue for sound localization and motion perception - contributed to the SIVM. In experiments, two alternating sound sources aligned in the vertical plane were presented, synchronized with a static visual stimulus. We found that the proportion of the SIVM and the magnitude of the perceived movements of the static visual stimulus increased with an increase of retinal eccentricity (1.875-30 degrees), indicating the influence of the spectral cue on the SIVM. These findings suggest that the SIVM can be generalized to the whole two dimensional audio-visual space, and strongly imply that there are common neural substrates for auditory and visual motion perception in the brain. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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  • Atropisomeric 4-Phenyl-4H-1,2,4-triazoles as Selective Glycine Transporter 1 Inhibitors

    Sugane, Takashi   Tobe, Takahiko   Hamaguchi, Wataru   Shimada, Itsuro   Maeno, Kyoichi   Miyata, Junji   Suzuki, Takeshi   Kimizuka, Tetsuya   Sakamoto, Shuichi   Tsukamoto, Shin-ichi  

    We report on the optimization of 4H-1,2,4-triazole derivatives to increase their activity and selectivity as glycine transporter 1 (GlyT1) inhibitors. Structure-activity relationship exploration resulted in the identification of a 3-[3-ethyl-5-(6-phenylpyridin-3-yl)-4H-1,2,4-triazol-4-yl]-2-methyl-benzonitrile (14u) compound with markedly higher selectivity for GlyT1. Physiochemical studies revealed that 14u exists as a stable pair of atropisomers under physiological conditions. We successfully separated the atropisomers to obtain active enantiomer (R)-14u, which displayed favorable pharmacokinetic properties, as well as positive results in the mice Y-maze test.
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  • Integrated fluorescent cytology with nano-biologics in peritoneally disseminated gastric cancer

    Watanabe, Megumi   Kagawa, Shunsuke   Kuwada, Kazuya   Hashimoto, Yuuri   Shigeyasu, Kunitoshi   Ishida, Michihiro   Sakamoto, Shuichi   Ito, Atene   Kikuchi, Satoru   Kuroda, Shinji   Kishimoto, Hiroyuki   Tomida, Shuta   Yoshida, Ryuichi   Tazawa, Hiroshi   Urata, Yasuo   Fujiwara, Toshiyoshi  

    Gastric cancer patients positive for peritoneal cytology are at increased risk of tumor recurrence, but although a certain proportion of cytology-positive patients relapse rapidly with aggressive progression, others survive longer with conventional chemotherapies. This heterogeneity makes it difficult to stratify patients for more intensive therapy and poses a substantial challenge for the implementation of precision medicine. We developed a new approach to identify biologically malignant subpopulations in cytology-positive gastric cancer patients, using a green fluorescent protein (GFP)-expressing attenuated adenovirus in which the telomerase promoter regulates viral replication (TelomeScan, OBP-401). The fluorescence emitted from TelomeScan-positive cells was successfully quantified using a multi-mode microplate reader. We then analyzed clinical peritoneal washes obtained from 68 gastric cancer patients and found that patients positive for TelomeScan had a significantly worse prognosis. In 21 cytology-positive patients, the median survival time of those who were TelomeScan positive (235days) was significantly shorter than that for those who were TelomeScan negative (671days; P=3D0.0062). This fluorescent virus-guided cytology detects biologically malignant cancer cells from the peritoneal washes of gastric cancer patients and may thus be useful for both therapy stratification and precision medicine approaches based on genetic profiling of disseminated cells.
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  • RUBBER COMPOSITION AND PNEUMATIC TIRE USING THE SAME

    Disclosed is a rubber composition comprising a rubber component and at least one of a terpene resin and a rosin resin in an amount of 0.5 part by mass relative to 100 parts by mass of the rubber component, wherein the rubber component contains a natural rubber component comprising at least one of a natural rubber and a modified natural rubber at a ratio of 20 to 100% by mass. Also disclosed is a pneumatic tire comprising the rubber composition. It becomes possible to provide: a rubber composition which uses a raw material derived from a petroleum resource in a reduced amount, can maintain the properties required for the intended use application and has improved processability; and a pneumatic tire using the rubber composition.
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  • Selective effects of auditory stimuli on tactile roughness perception

    Suzuki, Yuika   Gyoba, Jiro   Sakamoto, Shuichi  

    We report two psychophysical experiments designed to investigate the effects of non touch-produced sounds on the tactile perception of roughness and length. Previous studies have demonstrated that the tactile roughness perception of object surfaces is modified by sounds elicited by rubbing the surfaces. In this study, we examined the crossmodal effects of non touch-produced sounds such as white noise (Experiment 1) and pure tones (Experiment 2). Participants touched abrasive paper, synchronizing their touch with changes in the intensity of sounds or with the onset of beeps (control condition), and judged the tactile roughness or length of the stimuli, using the magnitude estimation method. Although the white noise (complex sound) significantly decreased the slope of the roughness estimation function, it did not affect that of the length estimation function. Pure tones had no effect on roughness or length perception. The results revealed that complex sounds selectively affected tactile roughness perception, even when they were seemingly irrelevant to the exploration of the surfaces. We suggest that the processing of complex sounds may be related to the processing of tactile roughness, whereas it is independent of tactile length processing. (c) 2008 Elsevier B.V. All rights reserved.
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  • Use of Porphyra spheroplasts as feed additive for red sea bream

    Kalla, Alok   Araki, Toshiyoshi   Zhang, Dong-Ming   Yamamoto, Takeshi   Sakamoto, Shuichi  

    Two test diets with and without 5% Porphyra spheroplasts (PS) were formulated using white fishmeal as the main protein source. Red sea bream Pagrus major (mean body weight 15.4 +/- 0.1 g) were maintained in a flow-through system (100 L) of thermo-controlled sea water (salinity 32-34, 25 degrees C, 8 L/min) with ordinary aeration (400-600 mL/min) under laboratory light conditions (light-dark 12 h:12 h). Fish were fed three times a day at 10:00, 14:00 and 18:00 hours by hand for 42 days at 6% body weight on each experimental diet. Studies revealed that growth performance, survival and nutrient retention were significantly (P < 0.05) higher in the groups fed a diet containing spheroplasts (PS diet). Further, the fish fed the PS diet showed significantly (P < 0.05) lower feed conversion rates. Both groups of the PS and control diets had similar levels of body nutritional profile in terms of proximate compositions and fatty acids without compromising blood serum related parameters. From these experimental results, thus, it is comprehensible that a supplementary diet containing Porphyra spheroplasts can be used for maximizing not only growth of P. major but also for utilization of the feed ingredients.
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