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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 127 (1994), S. 236-239 
    ISSN: 0942-0940
    Keywords: Cavernous angioma ; ECoG ; epileptogenic focus ; surgical treatment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In a case of cavernous angioma, a remote gyrus, which was found to contain an epileptogenic focus by intraoperative electrocorticography (ECoG), was resected simultaneously with lesionectomy. The patient was a 27-year-old male who was referred to our hospital because of frequent systemic tonic-clonic convulsions. ECoG revealed an epileptogenic focus not only in the cortex around the angioma-affected tissue of the left frontal lobe but also in an in addition to lesionectomy. The postoperative course was uneventful. Now (two years after surgery), the patient is seizure-free In the surgical treatment of convulsions-accompanied by cavernous angioma, it is essential not only to detect epileptogenic foci by intraoperative ECoG but also to remove these foci together with the angioma.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta neurochirurgica 107 (1990), S. 152-160 
    ISSN: 0942-0940
    Keywords: Chiari malformation ; magnetic resonance image ; syringomyelia ; syringo-subarachnoid shunt
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors report the surgical results of 28 patients with syringomyelia associated with Chiari malformation (type 1). 28 patients underwent 34 operative procedures. Syringo-subarachnoid shunt was performed in 28 patients, foramen magnum decompression with syringo-subarachnoid shunt in three, ventriculo-peritoneal shunt in one, terminal syringostomy in one, and foramen magnum decompression with terminal syringostomy in one. In an average postoperative follow-up period of 3 years and 9 months ranging from one year to 7 years and one month, neurological symptoms and signs improved in 24 out of 28 patients (82%). Some improvement was noted in sensory deficit and motor weakness. In 3 patients, the symptoms did not change. In 3 patients whose symptoms were unchanged, preoperative studies demonstrated atrophy of the spinal cord, in which irreversible changes were shown. The symptoms deteriorated in one patient. In one patient whose symptoms increased 3 months after syringo-subarachnoid shunt, shunt insufficiency due to postoperative adhesive arachnoiditis was responsible for neurological deterioration. The authors propose that syringo-subarachnoid shunt is effective as a surgical procedure for syringomyelia associated with Chiari malformation (type 1) if the patient does not have symptoms due to Chiari malformation or has only mild signs and symptoms which do not require foramen magnum decompression, such as nystagmus or atrophy of sternocleidomastoid muscle.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 0942-0940
    Keywords: Keywords: Anterior cervical decompression; cervical disc disease; vertebral column autograft using the intervertebral disc
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We describe a surgical technique for a vertebral column autograft using the intervertebral disc for cervical disc disease for patients whose major problem is not spinal instability. Of a total of 41 patients with cervical disc disease suffering from cervical spondylotic radiculomyelopathy, 33 patients were operated on at one level and 8 patients were operated on at two levels. Postoperative X-ray film showed some movement at the “operated” disc level in all patients (average postoperative follow-up period was 43 months, range two years to 5 years). A significant decrease in motion in the extension position was observed postoperatively (p〈0.0001), but no significant difference was observed between the preoperative motion and the postoperative motion in the flexion position. Anterior angulation was found in two (5%) of the 41 patients. This surgical procedure has two major advantages: 1) no complications related to the iliac donor site, allowing early patient mobilization; 2) the extensive posterior spur can be removed safely and easily under a wide operative field. We believe that this surgical procedure is suitable for preserving the mobility of the spine and may avoid stress concentration at adjacent levels of the “operated” disc. However, in patients whose major problem is spinal instability, anterior cervical fusion should be performed.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Hemifacial spasm ; intra-operative monitoring ; microvascular decompression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The facial electromyographic response was monitored intraoperatively in 40 patients with hemifacial spasm who were operated on by microvascular decompression of the facial nerve. All 40 patients showed an abnormal facial electromyographic response (lateral spread response) with a latency of about 10 msec after stimulation. The abnormal response resolved before decompression in 22, resolved immediately with decompression in 16, and failed to resolve in two. Of the 38 patients in whom the abnormal response disappeared during surgery, 36 were postoperatively free from hemifacial spasm and two had mild hemifacial spasm. The two patients in whom the lateral spread response did not disappear during surgery showed persistent hemifacial spasm. In conclusion. Disappearance of the lateral spread response during surgery correlated with the absence of hemifacial spasm in the early postoperative period. The prognosis of hemifacial spasm was good in cases in whom the lateral spread response disappeared. Therefore, the authors think that intra-operative facial electromyography is very useful in assessing the efficacy of microvascular decompression and in predicting the prognosis of hemifacial spasm.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 64 (1994), S. 1123-1125 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The spatial variation of the growth rate on mesa-etched GaAs (1¯1¯1¯)B substrates during molecular beam epitaxy of GaAs is measured from the period of the reflection high-energy electron diffraction (RHEED) intensity oscillation using in situ scanning microprobe RHEED. The surface diffusion length of Ga adatoms on the (1¯1¯1¯)B surface is determined from the spatial variation of the growth rate. The surface diffusion length on the (1¯1¯1¯)B surface increases as the substrate temperature is raised or the arsenic pressure is decreased. The typical value of the diffusion length is about 10 μm at a substrate temperature of 580 °C and an arsenic pressure of 5.7×10−4 Pa, which is an order of magnitude larger than that on the (100) surface along the [011] direction. The activation energy of the surface diffusion length changes with the surface reconstruction. Anisotropic diffusion, as reported for the (100) surface, is not observed on the (1¯1¯1¯)B surface.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 8231-8233 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The sheet resistances of ZnSe epitaxial layers etched by reactive ion etching (RIE) with use of a gas mixture of ethane and hydrogen were measured. The results showed that a high resistivity region was introduced by RIE. Characterization was done by transforming the measured resistances to the electrically active thickness estimated from the resistivity of as-grown ZnSe layers. The estimated electrically active thicknesses were smaller than the thickness of ZnSe epitaxial layers remaining after RIE, for both p- and n-ZnSe. The influence of heat treatment and current injection on the high resistivity regions differed between p- and n-ZnSe.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 63 (1988), S. 845-852 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We present a systematic investigation of (GaAs)l(AlAs)m (l(approximately-equal-to)m) superlattices by photoluminescence excitation at T=2 K in the energy range of 1.52–2.42 eV. The luminescence spectra of the superlattice samples differ strongly from the spectra of the ternary Al0.5Ga0.5As alloy. The luminescence peak energy is largest for l,m=3 and decreases when l,m〈3. The superlattices with l,m≤15 show sidebands of low intensity. The excitation spectra for superlattices with l,m≤8 show threshold energies but no discrete states corresponding to light-hole related transitions. Superlattices with l,m〉15 display a splitting of light- and heavy-hole states. The optical measurements confirm that this new material has properties which are very different from the ternary Al0.5Ga0.5As alloy.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 63 (1993), S. 1339-1341 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Scanning tunneling microscope has been employed for intentional movement of C60 molecules adsorbed on Si(111)-7×7 surface. Threshold conditions at which a C60 molecule starts moving from its adsorption site are investigated in relation to tunnel current and tip bias voltage. We find that there exists threshold height for the movement process. The threshold height estimated from a planar electrode model is in agreement with the vertical height of the adsorbed C60 molecules. Present results evidence that direct contact or close proximity between a mechanical probe and C60 molecules is required for movement of the molecules to occur.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2542-2544 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Microscopic distribution of growth rates on mesa-etched GaAs(001) wafers was measured in real time during molecular beam epitaxy growth by scanning microprobe reflection high-energy electron diffraction. It has been observed that the growth rate on the GaAs(001) surface near the edge of (111)A surfaces becomes larger. The exponential variation of the growth rate as a function of the distance from the edge reflects surface diffusion of Ga atoms. The diffusion length on the (001) surface is estimated to be about 1 μm at 560 °C. The relatively larger diffusion length suggests that the incorporation rate of migrating Ga atoms by steps is much smaller than unity.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We investigate the room-temperature photoluminescence of single In0.1Ga0.9As/Al0.33Ga0.67As quantum wells grown simultaneously on (100), (311)A, and (311)B GaAs substrates. The measurements, taken under both steady state and transient conditions, evidence that nonradiative (Shockley-Read-Hall) recombination dominates the emission of both the [100] and [311]B oriented samples at low injection levels, and is still important up to injection levels approaching those in lasers. The emission of the [311]A oriented sample is, in contrast, dominated by radiative recombination already at modest injection levels. The origin of this remarkable feature of the [311]A oriented sample is traced back to the reduced incorporation of deep recombination centers at the (311)A In0.1Ga0.9As/Al0.33Ga0.67As interface. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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