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Focuses on a study that investigated gallium arsenide[subl] and aluminum arsenide[subm] superlattices by photoluminescence excitation. Details of the experiment; Calculations; Conclusions.

Investigates the characterization of zinc selenide (ZnSe) epitaxial layer reactive-ion-etched by a gas mixture of ethane and hydrogen. Measurement of the sheet resistance of ZnSe epitaxial layers; Details on the estimated electrically active thicknesses; Importance of reactive ion etching for the fabrication of compound semiconductor devices.

Many researching efforts have been reported to seek various fundamental LC resonance structures, recently. But still the Split Ring Resonator (SRR) is the most famous and major fundamental LC-resonance structure used in the metamaterial. We employed SRR structure as the fundamental LC-resonance mechanism to fabricate photonic crystal with periodic arrangement of two different metamaterial areas composed from SRR arrays on the dielectric substrate. We developed Photonic Metamaterial Crystal (PMC) to realize the more advanced and versatile functions of the metamaterial by 1 dimensional or 2 dimensional periodic arranging of two metamaterial sections which have different dispersion properties due to the different size of SRR structures each other. In this paper, we report the fabrication process, estimation of PMC properties and some possible future application prospects, for instance the PMC waveguide structures and nonlinear properties of PMC observed as selective LC-resonant properties in Raman mapping analysis of PMC. These are quite interesting characters of PMC and the attractive applications as the PMC devices. [ABSTRACT FROM AUTHOR]

Light propagation effects on nonlinear optical response of a size-controlled GaAs thin film at exciton resonance are investigated by transient grating using picosecond pulses (1.5 ps). The signals are enhanced at the exciton resonance and the temporal profiles strongly depend on the excitation pulse energies. The result indicates that the nonlinear response is induced by excitonic polaritons and its decay is determined by the round-trip of the polariton in the film. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine factors that might be involved in neurological deterioration and the role of surgical treatment in patients with lumbosacral spinal lipoma. Pre- and postoperative courses of 34 patients were retrospectively analyzed. The age at surgery ranged from 1 month to 47 years. The records of preoperative neurological status indicated that older patients had more severe deficits, while all 8 asymptomatic patients were under 5 years of age. Motor deficits were noted in 9 patients, in 7 of whom the lipoma extended cranially beyond the L5 level. Transitional-type lipomas were accompanied by more severe deficits (asymptomatic 1, symptomatic 17) than other types (asymptomatic 7, symptomatic 9). Postoperative follow-up periods ranged from 5 months to 13 years. During these periods, 7 of the 8 asymptomatic patients remained neurologically intact. Nine of the 26 symptomatic patients improved. Age, extension of the lipoma in the spinal canal and type of lipoma will influence the preoperative neurological status of the patients. Early untethering surgery is recommended in patients with large lipomas extending beyond the L5 level. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The clinical features of 31 cases of syringomyelic syndrome, confirmed by metrizamide CT myelography (CTM) or magnetic resonance imaging (MRI), were analysed. Bilateral suspended sensory disturbance, previously regarded as a characteristic feature, was encountered in only 2 cases (6.5%). Thirteen patients (41.9%) showed no motor deficits of the upper limbs and 7 patients (22.6%) did not have weakness or atrophy in any of the four extremities. Cervical segmental signs were absent in 7 cases (22.6%) and in 2 (6.5%) signs were only present in the lower limbs. Scoliosis and foot deformity, such as pes cavus or equinovarus, were seen in 17 (54.8%) and 5 cases (16.1%) respectively. These skeletal abnormalities were initial symptoms in some childhood cases. In syringomyelic syndrome, clinical features are variable with many atypical clinical manifestations, apart from the previously recognized characteristic clinical features. [ABSTRACT FROM AUTHOR]

Herniated nuclear material of the cervical disc often perforates the posterior longitudinal ligament. Of 22 patients who were operated on by an anterior approach, 10 were of this type (the subligamentous type of cervical disc protrusion), while in the remaining 12 patients and 15 discs the protruded disc caused no tear in the ligament (the epiligamentous type). Myelography and CT myelography of these patients were reviewed. On CT myelography a localized and sharply demarcated excavation of the metrizamide ring was commonly found in the subligamentous type. Myelographic lateral view in this group shows a moderate or large indentation of the metrizamide column, since the herniated nucleus pulposus sometimes migrates caudally or cephalically. A small myelographic deformity coupled with diffuse excavation of the metrizamide ring on a CT myelogram leads us to the diagnosis of the epiligamentous type of cervical disc protrusion. In such cases, excision of the ligament is unnecessary during exploration of the discs, except when there is marked depression in the posterior longitudinal ligament. Presurgical recognition of both anatomical processes must be stressed for anterior discectomy. [ABSTRACT FROM AUTHOR]

In this study, the authors evaluate the importance of computed tomography (CT) in 15 patients who underwent surgical treatment for cervical disc disease. In nine operated on by an anterior approach, all CT examinations were interpreted as positive for disc herniation and correlated precisely with surgical observations. CT demonstrated protrusion of the disc, centrally in four and posterolaterally in five in all of whom disc material was found posterior to the vertebral body. Of six who underwent laminectomy, either thickening or calcification of the ligamentum flavum was demonstrated by CT and confirmed at surgery in five. Vacuum phenomenon in the intervertebral space and hypertrophy of the intervertebral joint were not infrequently associated. CT can exactly delineate cervical disc lesions and associated pathological changes. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

We retrospectively evaluated the pre- and postoperative course of 34 tethered cord patients with occult spinal dysraphism in an attempt to infer the natural history of this disorder and to determine the effectiveness of the surgical treatment. There were 32 cases with lumbosacral lipoma and 2 with tight filum terminale. The age at surgery ranged from 1 month to 47 years old. Eight patients, aged 1 month to 4 years old, were asymptomatic; 26 had neurogenic bladder (26 cases) or motor problems affecting the legs (8 cases). None of the patients older than 5 years of age were asymptomatic. Untethering of the spinal cord was performed in all cases. The postoperative follow-up period ranged from 5 months to 11 years. During these periods, 7 (88%) of the 8 asymptomatic patients remained neurologically intact, 6 (23%) of the 26 symptomatic patients showed improved symptoms, and 15 patients (58%) remained unchanged. These results indicate that the neurological symptoms will appear progressively in the tethered cord patients, and that prophylactic surgery should be considered as early as possible. [ABSTRACT FROM AUTHOR]

Clinical and radiological features of syringomyelia in 15 patients with spinal dysraphism are reported. There were 8 patients with occult spinal dysraphism (lumbosacral lipoma) and 7 with spina bifida aperta (meningomyelocele). Syringomyelia with spinal dysraphism can be radiologically divided into two types according to the dysraphic state. The syrinx in the patients with occult spinal dysraphism occurred immediately rostral to the lipoma and was localized to the lower thoracic to lumbar levels, while in the meningomyelocele patients the syrinx extended from the cervical to the thoracic level. Large syrinx formation was recognized in 1 of the 7 occult spinal dysraphism cases and 3 of the 8 meningomyelocele cases. For syringomyelia with occult spinal dysraphism, 4 patients underwent syringo-subarachnoid shunting (S-S shunt, 2 cases) or syringostomy (2 cases) during an untethering operation. In the case of meningomyelocele, S-S shunts were placed in 2 patients. Collapse of the syrinx was achieved in all 6 patients who underwent S-S shunting or syringostomy. Decreased size of the syrinx was also noted in 3 occult spinal dysraphism patients who underwent untethering operations alone. In conclusion, a large syrinx in the case of spinal dysraphism should be surgically treated. S-S shunting is effective in both types of syringomyelia. Foramen magnum decompression may be an alternative method of surgical treatment for syringomyelia in patients with meningomyelocele. [ABSTRACT FROM AUTHOR]

We describe the epitaxial growth of GaAsP (0 < x < 0.7) on GaAs(00l) substrates using mass-separated low-energy P ions, and Ga and As molecular beams. Epilayers have been obtained at growth temperatures (Tg) ranging from 300 to 650° C at P ion energies (E ) between 50 and 300 eV. We have investigated the growth rate as a function of E , and the film composition as a function of the flux ratio of As to P, T and E . The sticking coefficient of phosphorus is markedly enhanced by using P ion, compared with that of As. As the flux ratio of As to P is increased from 0 to 8, the composition ratio x of GaAsPfilms varies from 0 to 0.5. The composition ratio x decreases slightly with increasing T from 400 to 650° C, and increases with increasing E . Film surfaces are smooth at E below 100 eV, and their morphology is degraded with increasing energy. [ABSTRACT FROM AUTHOR]

We report a patient with bow hunter’s syndrome who was treated by anterior decompression of the vertebral artery (VA) using an ultrasonic bone curette (SONOPET). This 60-year-old man reported almost losing consciousness upon head rotation. Although the right VA appeared normal at the natural head position, upon left head rotation it became completely occluded at the transverse foramen of C2. We performed anterior decompression of the right VA at the axis using a high-speed drill and SONOPET. For anterior decompression of the VA in a deep and narrow operative field, we recommend use of SONOPET, which permits safe, easy bone dissection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The article presents a case study of ligamentum flavum (LF) hemorrhage in the lumbar spine. The case was taken from a 67-year-old man who experienced pains in his left leg four weeks after an accident. The patient underwent magnetic resonance imaging and it was discovered that the limbar canal stenosis and the left LF at L4 to L5 was expanded a little and has abnormal intensities. Prognosis was done under laminectomy and excision of the LF and revealed a good result.