In this study, we used high-speed video microscopy with motion vector analysis to investigate the contractile characteristics of hiPS-CM monolayer, in addition to further characterizing the motion with extracellular field potential (FP), traction force and the Ca(2+) transient. Results of our traction force microscopy demonstrated that the force development of hiPS-CMs correlated well with the cellular deformation detected by the video microscopy with motion vector analysis. In the presence of verapamil and isoproterenol, contractile motion of hiPS-CMs showed alteration in accordance with the changes in fluorescence peak of the Ca(2+) transient, i.e., upstroke, decay, amplitude and full-width at half-maximum. Simultaneously recorded hiPS-CM motion and FP showed that there was a linear correlation between changes in the motion and field potential duration in response to verapamil (30-150nM), isoproterenol (0.1-10μM) and E-4031 (10-50nM). In addition, tetrodotoxin (3-30μM)-induced delay of sodium current was corresponded with the delay of the contraction onset of hiPS-CMs. These results indicate that the electrophysiological and functional behaviors of hiPS-CMs are quantitatively reflected in the contractile motion detected by this image-based technique. In the presence of 100nM E-4031, the occurrence of early after-depolarization-like negative deflection in FP was also detected in the hiPS-CM motion as a characteristic two-step relaxation pattern. These findings offer insights into the interpretation of the motion kinetics of the hiPS-CMs, and are relevant for understanding electrical and mechanical relationship in hiPS-CMs.

Background: One of the goals for a Whole Slide Imaging (WSI) system is implementation in the clinical practice of pathology. One of the unresolved problems in accomplishing this goal is the speed of the entire process, i.e., from viewing the slides through making the final diagnosis. Most users are not satisfied with the correct viewing speeds of available systems. We have evaluated a new WSI viewing station and tool that focuses on speed. Method: A prototype WSI viewer based on PlayStation®3 with wireless controllers was evaluated at the Department of Pathology at MGH for the following reasons: 1. For the simulation of signing-out cases; 2. Enabling discussion at a consensus conference; and 3. Use at slide seminars during a Continuing Medical Education course. Results: Pathologists were being able to use the system comfortably after 0–15 min training. There were no complaints regarding speed. Most pathologists were satisfied with the functionality, usability and speed of the system. The most difficult situation was simulating diagnostic sign-out. Conclusion: The preliminary results of adapting the Sony PlayStation®3 (PS3®) as an ultra-high speed WSI viewing system were promising. The achieved speed is consistent with what would be needed to use WSI in daily practice.

No abstract

For hard disk drives (HDD's) having multiple disk rotational speeds, a new data channel and head positioning servo system was developed. Head positioning performance at the low spin-speed was preserved by using a synchronous servo scheme with more servo areas than the conventional scheme. Using a common physical disk format, sufficient servo performance and the same data recording density of 1.3 Gbit/inch 2 were obtained on two 2.5 inch prototype HDD's with a low spin-speed 37.5 Hz and a high spin-speed of 75 Hz. Disk interchangeability was also confirmed.Index Terms-Magnetic disk drive, disk rotational speed, sampling frequency, synchronous servo.

A coherent digital maximum-likelihood (ML) head position estimator was proposed and examined for sampled-servo magnetic disk drives. Estimating the ML head position is obtained through four ML amplitude estimators of each servo mark readback pulse. When compared to a conventional analog integration detector, about 1.7 dB improvement in position estimation accuracy was obtained. To generate a servo clock for coherent estimation, an ML phase estimating digital phase-locked loop (DPLL) was also developed. Since five inner product operations for amplitude and phase estimation are performed by a time-shared multiplier-accumulator, this ML head position estimator is applicable for use in small scale hardware and adaptable to IC's.