Multiplication-dependent frequency responses of InP/InGaAs avalanche photodiode

The intrinsic response time of InP/InGaAs APD has been reported. The multiplication factor dependent frequency responses were measured up to multiplication factor of 24. The results show the gain bandwidth of InP/InGaAs APDs is 10 GHz, and the intrinsic response time to be 16 ps.     

Liquid-phase-epitaxial growth of Inp/InGaAsP/InGaAs buried-structure avalanche photodiodes

An InP/InGaAsP/InGaAs avalanche photodiode with an effective guard-ring structure has been successfully fabricated. The diode has a planar structure with an n-InP layer buried by n?-InP in the multiplication region The structure has been grown on a (111)A-oriented InP substrate by two-step growth of liquid-phase epitaxy. Prior to the second growth of n?-InP a meltback technique was used to reduce dark current.     

Application of ultrafast 3D-CT in cervical spine injury

The authors investigated the usefulness of the ultrafast three-dimensional computed tomography (UF-3D-CT) in cervical spine injury. At Osaka City General Hospital, between April 1995 and March 1998, the authors examined 38 patients with cervical spine injury using UF-3D-CT. The ultrafast CT reduces scanning time. There were no complications associated with the examination. We examined 12 patients with vertebral body fracture, 11 patients with lamina fracture, 8 cases with subluxation including locking facet, 2 patients with atlanto-axial dislocation and 8 patients without bony abnormality. Results suggested that UF-3D-CT was very useful for helping us to understand the bony deformity and the relationship between the bone and the important vessels. UF-3D-CT is very useful for preoperative evaluation and pathophysiological evaluation in cervical spin injury.     

Parallel video signal processor configuration based on overlap-save technique and its LSI processor element: VISP

A parallel signal processor architecture has been developed for real time motion picture encoding. The architecture is based on spatial parallelism utilization in a picture signal. Plural element processors handle subregional pictures simultaneously without communicating with other element processors. However, due to an overlapsave technique where every sub-picture input area is chosen to be wider than the output area, element processors can carry out continuous processing over an entire picture. In order to increase motion picture processing efficiency as well as system implementation simplicity, a specific element processor LSI chip, composed of a pipeline arithmetic unit, two dimensional address generators, a raster scan signal handler, and a sequence controller, has been developed by using more than 220,000 transistors. The developed parallel processor is shown to be applicable to a software programmable low bit rate TV codec.     

pH-linked binding of Mn(II) to manganese peroxidase

The stability of Mn(II) binding to manganese peroxidase (MnP) has been studied as a function of pH by spectrophotometric and potentiometric titrations. The sensitivity of the potentiometric titrations allows collection of data that are consistent with a high-affinity and a low-affinity Mn(II) binding site on the peroxidase. The two sites differ in affinity by 4 to 900-fold between pH 4 and 6.5. The stability of Mn(II) binding to the high-affinity site increases with increasing pH, while the stability of Mn(II) binding to the low-affinity site decreases with increasing pH. Interestingly, at pH values above 5.0, the high-affinity site appears to be partially unavailable for binding Mn(II). A pH-dependent structural change in the Mn(II) binding site is proposed to account for this partial inactivation at elevated pH.     

The role of the premacular liquefied pocket and premacular vitreous cortex in idiopathic macular hole development

PURPOSE: To clarify the role of the vitreous in idiopathic macular hole formation. METHODS: We prospectively evaluated the vitreous before and during vitreous surgery in 64 consecutive eyes of 62 patients (stage 1B, four eyes; stage 2, ten eyes; stage 3, 43 eyes; stage 4, four eyes) with macular holes; another three eyes underwent a second vitrectomy. After core vitrectomy, the premacular vitreous cortex was examined by applying gentle suction. The detached posterior hyaloid face was observed under endoilluminiation. RESULTS: We observed in all eyes a liquefied lacuna anterior to the posterior fundus before and during vitreous surgery. The premacular vitreous cortex was extremely thin and elastic upon gentle suction. A premacular ring, the diameter two to four times that of the Weiss ring, was observed in 48 of 57 eyes (84%) with stages 1B, 2, and 3 macular hole. In most cases, the vitreous cortex within the premacular ring either was absent or had a break, resulting in a premacular round defect. The vitreous cortex peripheral to the premacular ring, which was thick and less deformed, never showed a break. In eyes that had undergone a second vitrectomy, we noted residual cortex or an epiretinal membrane around the macular hole. CONCLUSIONS: The premacular vitreous cortex is extremely thin and elastic. It is sharply demarcated by a ring from the thick peripheral vitreous cortex. Tangential traction, which causes macular holes, appears to originate exclusively in the premacular vitreous cortex that forms the posterior wall of the premacular liquefied pocket.