M Ishiguro

Publications (6)7.43 Total impact

• Article: Detection and Visualization Method of Dynamic State Transition for Biological Spatio-Temporal Imaging Data

  F. Miwakeichi, Y. Oku, Y. Okada, S. Kawai, Y. Tamura, M. Ishiguro
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  ABSTRACT: In the statistical analysis of functional brain imaging data, regression analysis and cross correlation analysis between time series data on each grid point have been widely used. The results can be graphically represented as an activation map on an anatomical image, but only activation signal, whose temporal pattern resembles the predefined reference function, can be detected. In the present study, we propose a fusion method comprising innovation approach in time series analysis and statistical test. Autoregressive (AR) models were fitted to time series data of each pixel for the range sufficiently before or after the state transition. Then, the remaining time series data were filtered using these AR parameters to obtain its innovation (filter output). The proposed method could extract brain neural activation as a phase transition of dynamics in the system without employing external information such as the reference function. The activation could be detected as temporal transitions of statistical test values. We evaluated this method by applying to optical imaging data obtained from the mammalian brain and the cardiac sino-atrial node (SAN), and demonstrated that our method can precisely detect spatio-temporal activation profiles in the brain or SAN.
  IEEE Transactions on Medical Imaging 04/2011; · 3.64 Impact Factor
• Conference Proceeding: Rotation phase analysis of surface particle motion of coiled waveguide caused by flexural ultrasound wave

  K. Tomoda, M. Ishiguro, M. Tanabe, K. Okubo, N. Tagawa
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  ABSTRACT: We have developed a traveling-wave-type miniature ultrasonic motor using a helical coiled waveguide as a stator. In this motor, the elliptical motion of the surface particle due to the flexural ultrasonic waves rotates the rotor, which can be placed adjacently inside or outside the stator, via the frictional force. In this motor, the rotation direction of the outer rotor is reverse to that of the inner rotor for a low frequency of the flexural wave. To clarify this phenomenon, we have confirmed that the rotation direction of the surface particle at the outer surface is same as that at the inner surface. In this study, we examine the rotation phase at the both surfaces.
  Ultrasonics Symposium, 2008. IUS 2008. IEEE; 12/2008
• Article: A procedure for tidal analysis with a Bayesian information criterion

  Y. Tamura, T. Sato, M. Ooe, M. Ishiguro
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  ABSTRACT: SUMMARYA computer algorithm for tidal analysis is developed, based on a Bayesian method proposed by Ishiguro et al. (1983). The basic assumption of the method is smoothness of the drift. This assumption is represented in the form of prior probability in the Bayesian model. Once the prior distribution is determined, the parameters used in the analysis model are obtained by maximizing the posterior distribution of the parameters. For the given data, ABIC (Akaike's Bayesian Information Criterion, Akaike 1980) is used to select the optimum values of the hyperparameters of the prior distribution and combination of parameters. The program, BAYTAP-G, can be adapted to tidal data which includes such irregularities as drift, occasional steps and disturbances caused by meteorological influences. The applicability of this program is examined using simulated data and real strain data.
  Geophysical Journal International 04/2007; 104(3):507 - 516. · 2.42 Impact Factor
• Conference Proceeding: Robust and precise length correction of 25-km fiber for distribution of local oscillator

  M. Musha, Y. Sato, K. Nakagawa, K. Ueda, A. Ueda, M. Ishiguro
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  ABSTRACT: In order to distribute local oscillators for the phased-array radio telescopes, the cycle-slip free fiber length stabilization system has been developed. The length of the 25-km fiber was precisely measured by the Michelson interferometer with a digital phase frequency discriminator, and the length fluctuation of which was suppressed down to 2.5 μm.
  LEOS Summer Topical Meetings, 2005 Digest of the; 08/2005
• Conference Proceeding: Multichannel VSB-AM transmission system using super-wideband frequency modulator and demodulator ICs

  M. Shibutani, K. Emura, M. Ishiguro, F. Saeki, J. Yoneda, Y. Hagiwara
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  ABSTRACT: Super-wideband FM modulator and demodulator ICs have been developed for multichannel VSB-AM transmission systems, and sensitivity improvement of 8 dB is demonstrated with the ICs. The ICs are promising for use in developing high-performance and cost-effective subcarrier multiplexed lightwave systems, such as optical fiber feeders for mobile radio or wireless applications, besides the CATV applications
  Optical Fiber Communication. OFC 97., Conference on; 03/1997
• Article: Cryogenically cooled K‐band high electron mobility transistor receiver for radio astronomical observation

  T. Kasuga, R. Kawabe, M. Ishiguro, K. Yamada, H. Kurihara, M. Niori, Y. Hirachi
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  ABSTRACT: A K‐band receiver using cooled high‐electron mobility‐transistor (HEMT) amplifiers was developed at the Nobeyama Radio Observatory (NRO). Remarkable reduction of receiver noise temperature T rec was obtained when it was cooled down to cryogenic temperature. The lowest T rec of 75 K was obtained at 23.4 GHz. This low noise characteristic reveals that the cooled HEMT amplifier is promising as a sensitive receiver for radio astronomical observations.
  Review of Scientific Instruments 04/1987; · 1.37 Impact Factor