Development of a hybrid helical microwiggler with four poles per period

A compact strong test hybrid helical microwiggler has been designed and developed with ten periods, each with length 10 mm and four poles, and gap diameter of 5 mm. One period is constructed with four segments. Each segment has a thickness of 2.5 mm and consists of pentagonal permanent magnets and permendur poles. Each segment is stacked along the wiggler axis and is rotated by an angle of 90/spl deg/ to the adjacent segment. The outer width is only 72 mm. The wiggler is divided into two sections where two kinds of permanent magnet - one with apex angle of 90/spl deg/ and one with 120/spl deg/ - were installed in order to find out the effect of geometrical size for the field. Peak fields of 0.360 and 0.381 T were achieved with small rms variations of about 1.1% and 0.6%, respectively, depending on the geometrical size of the permanent magnet.     

Melting of Solid 4He by Ultrasound at 1.2 K

We observed the melting of solid ⁴ He in superfluid when the sound waves were injected to its rough surface at 1.2 K. Single crystal was grown between two transducers and ultrasound pulses were applied normally to the solid-liquid interface from solid side or liquid side. Amount of melting was on the same order in both cases. We developed surface height measurement system using the sound wave itself and measured the amount of melting by changing the sound power and the number of pulses.     

Delineation of small nerves and blood vessels with three-dimensional fast spin-echo MR imaging: comparison of presurgical and surgical findings in patients with hemifacial spasm

BACKGROUND AND PURPOSE: We applied a 3D fast spin-echo (3D-FSE) MR imaging technique to the preoperative and postoperative evaluation of patients with hemifacial spasm. METHODS: The study group comprised 20 patients. All images were acquired on a 1.5-T MR system with a 3D-FSE sequence. RESULTS: In all 20 patients, the courses of the seventh and eighth cranial nerves were depicted separately, and the arteries presumed to be responsible for the hemifacial spasm were seen to be in contact with the facial nerves at the root exit zone (REZ). Eight patients underwent neurovascular decompression. In all patients, the presumed responsible blood vessels depicted by 3D-FSE MR imaging corresponded to intraoperative findings. In addition, postoperative 3D-FSE images confirmed the separation of the facial nerve from a contiguous vessel at the REZ. DISCUSSION: The 3D-FSE technique makes it possible to obtain extremely high-quality images of microstructures in the cerebellopontine cistern, and it has several advantages over conventional angiography: it is noninvasive and able to depict the cranial nerves and surrounding vessels in the same image without contrast material, and it may be useful for postoperative evaluation of the decompression procedure. This imaging technique is expected to prove useful for the clinical evaluation of hemifacial spasm.     

Shape error measurement using ray-tracing and fringe scanning methods: projection of grating displayed on a liquid crystal panel

We present an improved Hartmann test, which has high spatial resolution with respect to the measuring points, for measuring projection mirrors. In the method, grid lines with a sinusoidal transmittance distribution are displayed on a liquid crystal panel and illuminated with a collimated laser beam. The beam transmitted through the liquid crystal panel reflects off the mirror surface being tested and reaches a screen. A charge-coupled device camera detects the projected images, which contain information about the inclination of the surface being tested. Any error in the shape of the mirror surface is identified by integrating the inclination. To increase the spatial resolution, the fringe scanning method is performed by shifting the grid lines on the liquid crystal panel. The grid lines are optimized for the shape of the mirror being tested. Because the grid lines are displayed by an electrical method, the shifting operation is easy and rapid, and furthermore, the displacement can be done precisely. The shape error of an off-axis parabolic mirror made of plastic is measured by the proposed method.     

A histochemical study on the acidic glycoconjugates of the synovial membrane in rheumatoid arthritis

The localization and the nature of glycosaminoglycans (GAGs) in the synovial membrane in 30 patients with rheumatoid arthritis (RA) involving 40 knees were studied by newly developed histochemical methods. To detect the acidic glycoconjugates, sensitized diamine procedures were employed based upon high and low iron diamine stainings. To identify the various molecular species of the GAGs, enzyme (chondroitinase ABC and B, testicular hyaluronidase and keratanase) digestion and chemical modification (nitrous acid treatment) procedures were performed prior to the diamine stainings. The sensitized diamine methods could clearly stain the acidic glycoconjugates contained in the synovial tissue components in shades of brown to black, and could detect the precise distribution patterns of the GAGs. The results obtained in the present study confirmed that the tissue in RA synovial membranes contained various amounts of each GAG molecular species such as dermatan sulfate, chondroitin sulfate A/C, hyaluronic acid and heparan sulfate. Furthermore, the distribution patterns of dermatan and chondroitin sulfates in the diseased synovial tissues were pathophysiologically interesting; in the inflammatory areas, the molecular species of GAGs was primarily dermatan sulfate, whereas in the fibrotic areas, it was mainly chondroitin sulfate A/C. Such results appear to be useful for pathophysiological studies on the synovial tissues of RA.     

An improved Feynman-α analysis with a moving–bunching technique

The bunching technique has been widely utilized in Feynman-α neutron correlation analysis to synthesize neutron counts within longer gate widths by bunching time-sequence neutron counts stored in multichannel scaler channels. An alternative technique referred to as “moving–bunching technique” was proposed to reduce a statistical scatter of variance-to-mean ratio of neutron counts. The conventional bunching technique has no overlap of adjacent bunches, while the present technique makes adjacent bunches overlap as long as possible similarly to the moving average technique. A Feynman-α experiment was performed in the UTR-KINKI, to confirm the advantage of the proposed bunching technique. When a neutron detector was placed far from the core, a Feynman-α analysis with the conventional bunching technique led to a scattered variance-to-mean ratio from which the prompt-neutron decay constant was never determinable. However, another analysis with the proposed technique remarkably reduced the above scatter and enabled the determination of the decay constant. For a neutron detector close to the core, the proposed technique also reduced statistical error of the decay constant.     

Estimation of particle size distribution from cross-sectional particle diameter on the cutting plane

To control highly functional sintered materials, it is necessary to evaluate particle size segregation within materials. In the present study, a new method for estimating particle size distribution is proposed; this method considers the occurrence probability of the cutting diameter. The proper particle size distribution in a particle bed was estimated by calculating a matrix consisting of the occurrence probability and the distribution of particle diameters measured on a cutting plane. The estimated particle size distribution was smoothed using the Phillips–Twomey method. A cavity-filling simulation was carried out to verify the validity of the proposed method using the Distinct Element Method. The particle size distribution estimated by this method correlated well with the actual particle size distribution. The effect of particle size distributions with various geometrical standard deviations on the accuracy of estimated values was also investigated. The accuracy increased as the geometric standard deviation increased, and there was an optimum particle size bin number for a specific particle distribution. It was found that a large bin number and a large number of measured particles were required to obtain a higher accuracy for narrow size distributions.