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Nitric oxide (NO) acts as a modulator of neuronal transmission in mature neuronal systems, including the retina. Recently, NO has also been suggested to have a trophic function during development. We examined immunocytochemically the distribution of NO-producing cells in developing and transplanted rabbit retinas. An antibody detecting the neuronal isoform of its biosynthetic enzyme, nitric oxide synthase (NOS), was used on normal developing retinas [starting at embryonic day (E) 15] and on rabbit retinal transplants after various survival times (1-139 days after surgery). Weakly stained cell bodies were first observed in the proximal margin of the neuroblastic layer at E 29. Stained processes projecting towards a developing inner plexiform layer were also visible at this time point. Immunoreactive cells were located at later stages in the innermost part of the inner nuclear layer and in the ganglion cell layer, and are likely to correspond mainly to amacrine cells. NOS-labelled cells were also found in retinal transplants. The first NOS-labelled cells appeared, as in normal developing retinas, in ages corresponding to E 29 and were still detected in transplants corresponding to postnatal day 123. NOS-labelled cells were seen in areas between rosettes, where amacrine cells are located. NOS-labelled processes were at times seen to project for long distances, forming very distinct plexuses. NOS-containing amacrine cells thus appear both in the transplants and in developing retinas in the embryonic stages, long before synaptic function involving these cells can be expected, suggesting a role for NO not only in neuromodulation but also in retinal development.  相似文献   
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We report on compound formation in the system HgCdTeO. Samples were prepared by solid state reaction of mixtures of the binary oxide components. Specific phases were identified and characterized by X-ray and microprobe techniques. For some of these compounds small single crystals could be prepared and structural data of which are reported. Three groups of phases could be distinguished, most of them being of low symmetry, with Te in +4, +6, and in mixed oxidation states. The monotellurites HgTeO3 and CdTeO3 are structurally different and exhibit a large miscibility gap, whereas for the di-tellurites complete solid solution between CdTe2O5 and HgTe2O5 was found. As to the tellurates, phases with the compositions MTeO4 and M3Te2O9 (M = Hg, Cd) have been prepared. The Cd3Te2O9-structure is stabilized by 30 mole% Hg. Another tellurate, monoclinic Hg2TeO4, was found to be isomorphous to the respective selenate and sulfate and is identical with the mineral magnolite. The interaction of Te2O5 with the metal oxides led to the formation of mixed valence compounds with both Te(+4) and Te(+6) of the types M2Te2O7 and MTe2O6.  相似文献   
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The superconducting dipoles developed as part of the UNK project have reached a magnetic field 6 T at a rate of up to 0.8 T/sec. Experimental data are presented on the conditioning, rate dependences, and dynamic losses for magnets with two types of superconducting cable (zebra and oxide). Possible ways to decrease the heat release in a dipole operating in rapid-cycling magnetic fields are examined. The results of an analysis of heat release and temperature conditions are presented for a dipole with a winding made of improved current-carrying components.  相似文献   
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A device has been designed and fabricated to measure the cross-sectional area of soft connective tissues ex vivo. It consists of two displacement transducers; one sensing tissue thickness and the other sensing width. Outputs are recorded (via an analog to digital interface) using a personal computer. Numerical integration of a thickness versus width plot computes cross-sectional area. This plot also provides a quality check of acquired data. This device has been successfully used in biomechanical studies of rabbit patellar tendons, rat medial collateral ligaments, and dissected specimens of human fascia.  相似文献   
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The performance and architecture of a high dynamic range camera (HDRC) chip and the conceptional advantages for its adaptation to image processing systems in traffic environments are discussed. The HDRC chip was developed with 64×64 pixels using a standard digital 1.2-μm CMOS technology. It is shown that the implementation proves the functionality and indicates the system performance of a highly dynamic range camera is feasible  相似文献   
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OBJECTIVE: To assess postural performance in patients with dizziness of suspected cervical origin in whom extracervical causes had been excluded, and to assess the effects of physiotherapy on postural performance and subjective complaints of neck pain and dizziness. DESIGN: Prospective, randomized, controlled trial. SETTING: Primary care centers and a tertiary referral center. PATIENTS AND SUBJECTS: Of 65 referrals, 43 patients were excluded because extracervical etiology was suspected. Of the remaining 22 patients, 17 completed the study (15 women, 2 men, x age 37 yr, range 26-49). The controls were 17 healthy subjects (15 women, 2 men, x age 36 yr, range 25-55). INTERVENTION: Physiotherapy based on analysis of symptoms and findings, and aimed to reduce cervical discomfort. Patients were randomized either to receive immediate physiotherapy (n = 9), or to wait 2 months, undergo repeat measurements, and then receive physiotherapy (n = 8). MAIN OUTCOME MEASURES: Posturography, measuring velocity and variance of vibration-induced body sway and variance of galvanically induced body sway. Subjective intensity of neck pain (Visual Analog Scale ratings, 0-100), intensity and frequency of dizziness (subjective score 0-4). RESULTS: The patients manifested significantly poorer postural performance than did healthy subjects (.05 > p > .0001). Physiotherapy significantly reduced neck pain and intensity and the frequency of dizziness (p < .01), and significantly improved postural performance (.05 > p > .0007). CONCLUSIONS: Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.  相似文献   
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