Motion Generation in MR Environment Using Electrostatic Film Motor for Motion-Triggered Cine-MRI

This paper proposes a new methodology of biomechanical modeling for visualizing tissue deformation, combining an electrostatic film motor and tagged cine-MR imaging. The electrostatic film motor has a simple structure, is easily controlled by open loop, and its MR-compatibility has recently been verified. Tagged cine-MRI is an established process for measuring deformation of active objects. The newly proposed methodology enables the application of cine-MR imaging to passive objects. The electrostatic motor is used to create deformation on passive soft samples inside an MR scanner, the internal deformation of which is visualized by tagged cine-MR imaging. The force applied on the samples is measured by a force sensor fabricated on shielded strain gauges. The impact of the developed system on the MR imaging is verified through SNR evaluation. Then, the proposed methodology is applied to visualizing deformations of a gel sample and a human upper arm to verify the applicability of this methodology in biomechanical measurements.     

Flexible Independent Component Analysis

This paper addresses an independent component analysis (ICA) learning algorithm with flexible nonlinearity, so named as flexible ICA, that is able to separate instantaneous mixtures of sub- and super-Gaussian source signals. In the framework of natural Riemannian gradient, we employ the parameterized generalized Gaussian density model for hypothesized source distributions. The nonlinear function in the flexible ICA algorithm is controlled by the Gaussian exponent according to the estimated kurtosis of demixing filter output. Computer simulation results and performance comparison with existing methods are presented.     

Multimode fibers for compensating intermodal dispersion of graded-index multimode fibers

This paper proposes a novel type of multimode dispersion compensation fiber (MM-DCF) by which the intermodal dispersion of multimode fibers (MMFs) can be effectively compensated. A theoretical model that precisely calculates the group velocities of a target MMF and its MM-DCF and the power coupling between the two fibers is applied to confirm the proposal presented here. As a demonstration of the operation of the MM-DCF, an MMF optimized for transmission at a wavelength of 850 nm is compensated by the MM-DCF, and its overfilled launch bandwidth at a wavelength of 1300 nm is enhanced from 0.62 to 2.56GHz/spl middot/km.     

Very low resistance ohmic contacts to n-GaN

Ohmic contacts with low resistance are fabricated on n-GaN films using Al/Ti bilayer metallization. GaN films used are 0.3 μm thick layers with carrier concentrations of 1 × 10¹⁹ cm⁻³ grown on the c-plane sapphire by ion-removed electron cyclotron resonance molecular beam epitaxy. The lowest value for the specific contact resistivity (ρ_c) of 1.2×10⁻⁸ Ω·cm² was obtained with furnace annealing at 500°C for 60 min. This result shows the effectiveness of high carrier concentration GaN layers and the low temperature annealing for the realization of low resistance ohmic contacts. Sputtering Auger electron spectroscopy analysis reveals that Al diffuses into Ti layer and comes into contact with the GaN surface.     

ADP-ribosylation factor-1 is sensitive to N-ethylmaleimide

The treatment of normal rat kidney cells with N-ethylmaleimide caused the release of beta-COP, a component of coatomer, from the Golgi apparatus without causing disassembly of the organelle. The release of beta-COP, which was not due to depolymerization of microtubules, was markedly blocked by the activation of GTP-binding proteins by aluminum fluoride or a nonhydrolyzable analogue of GTP. To determine which component is N-ethylmaleimide-sensitive, we reconstituted the recruitment of coatomer from the bovine brain cytosol onto the Golgi apparatus in digitonin-permeabilized cells. In cells treated with N-ethylmaleimide before permeabilization, beta-COP was still recruited onto the Golgi apparatus. In contrast, beta-COP was not recruited when N-ethylmaleimide-treated bovine brain cytosol was used. These results suggest that the N-ethylmaleimide-sensitive factor(s) are present in the cytosol. It is known that coatomer and ADP-ribosylation factor-1 (ARF1) are the only cytoplasmic proteins needed for the assembly of Golgi-derived coated vesicles. N-Ethylmaleimide treatment of a coatomer-rich fraction did not affect the binding of beta-COP to the Golgi apparatus, whereas the same treatment of an ARF-rich fraction abolished beta-COP binding. Similar results were obtained using purified recombinant ARF1. Concomitant with inactivation, 0.85 mol of N-ethylmaleimide was incorporated into 1 mol of ARF1. ARF1 contains only one cysteine residue (Cys-159), which is located near the base moiety of the bound guanine nucleotide.     

High sensitivity and submillimeter resolution optical time-domainreflectometry based on low-coherence interference

Characteristics of the low-coherence optical time-domain reflectometer (OTDR) are presented, and optical waveguide diagnosis using the OTDR is demonstrated. Ultrahigh sensitivity in the shot noise limited operation is discussed, and jagged-shaped Rayleigh-backscatter signals are predicted and observed experimentally. Signal smoothing by widening the resolution from 14 to 400 μm can drastically reduce the jagging. In the experiment, polarization-sensitive and insensitive OTDRs using a fiber-coiled piezoelectric phase modulator are proposed. Measurements of beat length and bending loss, quality characterization of low-loss waveguides by polarization-sensitive OTDR, and cancellations of polarization fading in discrete backreflection and polarization jagging in Rayleigh backscattering by polarization-insensitive OTDR are successfully demonstrated     

Endothelin receptors in rat pituitary gland

An algorithm is described for reducing ghost artifacts in echo planar imaging (EPI) using phase corrections derived from images reconstructed using only even or odd k-space lines. The N/2 ghost, that arises principally from time-reversal of alternate k-space lines, was significantly reduced by this algorithm without the need for a calibration scan. In images obtained in eight subjects undergoing EPI for auditory functional MRI (fMRI) experiments, N/2 ghost intensity was reduced from 10.3% +/- 2.1% (range: 7.9-14.1%) to 4.5% +/- 0.2% (range: 4.1-4.9%) of parent image intensity, corresponding to a percent reduction in ghost intensity of 54% +/- 9% (range: 43-65%), and the algorithm restored this intensity to the parent image. It provided a significant improvement in image appearance, and increased the correlation coefficients related to neural activation in functional MRI studies. The algorithm provided reduction of artifacts from all polynomial orders of spatial phase errors in both spatial directions. The algorithm did not eliminate N/2 ghost intensity contributed by field inhomogeneities, susceptibility, or chemical shift.     

Elimination of polarization sensitivity in silica-based wavelengthdivision multiplexer using a polyimide half waveplate

This paper proposes a low-loss technique for eliminating polarization sensitivity in a silica-based planar lightwave circuit (PLC) which uses a polarization mode converter formed at the center of the circuit. This converter consists of a waveguide gap housing a polyimide half waveplate. The excess loss of the converter was drastically reduced to 0.26 dB with a Δ=0.75% waveguide by employing an 18 μm-wide waveguide gap and a 14.5 μm-thick polyimide half waveplate. A polarization mode conversion crosstalk of -37 dB was achieved at 1.55 μm. Using this converter, we successfully eliminated the polarization sensitivity in some silica-based PLC-type wavelength division multiplexers. The converter is also insensitive to temperature and offers long term stability     

Expression of rat cathepsin D cDNA in Saccharomyces cerevisiae: implications for intracellular targeting of cathepsin D to vacuoles

To investigate the intracellular transport mechanisms of lysosomal cathepsin D in yeast cells, we produced cathepsin D in Saccharomyces cerevisiae by placing the coding region under the control of the promoter of the yeast glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene. Immunoblotting analysis by the use of an antibody specific for rat cathepsin D coding sequence produced an intermediate species which had a slightly higher molecular weight than that of the mature cathepsin D. Cell fractionation experiments demonstrated that the cathepsin D polypeptide was colocalized to the yeast vacuoles with the marker enzyme carboxypeptidase Y in a Ficoll step gradient. A biosynthesis study with pulse-chase kinetic analysis revealed that the precursor polypeptide was accurately sorted to the yeast vacuoles as determined by cell fractionation, and that N-linked carbohydrate modifications were not required for vacuolar sorting of this protein. To elucidate the role of the propeptide region of cathepsin D, which might function in the intracellular targeting to the vacuole, a deletion mutant of cathepsin D lacking the propeptide was prepared and its intracellular targeting was examined after transfection into yeast cells. Immunoblotting analysis demonstrated that the propeptide-deleted mutant protein was recovered in a low quantity as compared with that in the case of yeast cells expressing the wild-type protein in the isolated vacuolar fraction. Immunofluorescence analysis revealed that the deletion mutant protein appeared to be accumulated within the intracellular small vesicles but not in the carboxypeptidase Y-positive vacuoles. Overall, these results indicate that the rat cathepsin D precursor polypeptide is recognized by mechanisms similar to those involved in the intracellular sorting of vacuolar proteins through the ER/Golgi/vacuolar sorting pathway in yeast cells, and that the propeptide has an important function in translocation of the cathepsin D polypeptide to the vacuole.     

Overvoltage phenomena caused by disconnecting motor-loads on power line with open-phase

This paper describes overvoltage caused by disconnecting a lot of motor-loads on a power distribution line with power-factor-correcting capacitors during a transmission line open-phase. The overvoltage phenomena are studied by a field test, a steady-state analysis and a transient analysis. Experimental results show that the line-to-line voltage on a 6.6 kV distribution line with an open-phase 22 kV transmission line amounts to 1.7 per unit. The overvoltages are caused by two types of resonance. One is the linear circuit resonance between the power-factor-correcting capacitors and the secondary side impedance of motors. The difference between positive components and negative ones of the impedance produces the resonance. The other is the nonlinear circuit resonance between the power-factor-correcting capacitors and the saturated reactances of a transformer.