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  • 1
    Digitale Medien
    Digitale Medien
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 57 (1990), S. 2294-2296 
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Inhomogeneities in waveguide dimensions are a serious problem for guided-wave frequency conversion devices. We discuss waveguide designs that make the phase matching "noncritical'' with respect to small changes in dimensions. Application of noncritical phase matching results in larger fabrication tolerances, facilitating the practical realization of nonlinear devices with long interaction lengths. We experimentally demonstrate the existence of a noncritical thickness in a lithium niobate waveguide, and analyze the dimensional tolerances for second-harmonic generation in a polymer waveguide.
    Materialart: Digitale Medien
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  • 2
    Digitale Medien
    Digitale Medien
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 7204-7210 
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Boron doping of silicon using a pulsed ArF excimer laser (λ=193 nm, FWHM=17 ns) with B2H6 has been investigated. Doping atoms are supplied mainly from both thermal and photochemical decomposition of the adsorbed layers on the surface. UV laser irradiation realizes both high surface carrier concentration (1×1021 cm−3) and a very shallow junction (0.1 μm). Diodes fabricated by laser doping show good electrical characteristics (n factor=1.10, reverse current density=1×10−7 A/cm2 at −5 V). Thermal annealing improves the reverse current density (3×10−9 A/cm2 at −5 V). A numerical calculation of boron concentration profiles has been performed by solving the diffusion equation in the melted region, which is evaluated by the heat conduction equation. From this calculation the diffusion coefficient of boron in liquid phase silicon (3×10−4 cm2/s) is obtained.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1435-1463
    Schlagwort(e): Yawning ; B-HT 920 ; SND 919 ; pindolol ; β-adrenoceptors ; dopaminergic neurons
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Subcutaneous injection of B-HT 920, a dopamine D2-receptor agonist, in doses ranging from 5 to 100μg/kg, induced yawning behavior in rats. Yawning was also elicited by low doses (25–500 μg/kg sc) of SND 919, a newly synthesized dopamine receptor agonist. The yawning evoked by B-HT 920 or SND 919 was increased by the β-adrenoceptor antagonist pindolol (20mg/kg ip) which alone did not induce yawning. Stereotyped behavior did not appear after B-HT 920 or SND 919 given alone or in combination with pindolol. The results suggest that SND 919 as well as B-HT 920 has stimulatory activity at dopamine D2-receptors, and that pindolol may exert its enhancement of the yawning response to dopamine receptor agonists via blockade of β-adrenoceptors.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Acta neuropathologica 80 (1990), S. 660-665 
    ISSN: 1432-0533
    Schlagwort(e): Juvenile amyotrophic lateral sclerosis ; Neurofibrillary tangles ; Putamen ; Motor cortex ; Motor neuron disease
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary A 36-year-old man developed motor neuron signs consisting of weakness and atrophy of the right upper limb, which progressed to involve the other limbs along with development of upper motor neuron signs including pseudobulbar palsy. He died 8.5 years after onset. Bilateral precentral gyri and putamina were grossly atrophic. In addition to severe degeneration of bilateral pyramidal tracts and marked neuronal cell loss of the precentral gyri and putamina, basophilic inclusions were widely distributed in the motor cortex, putamina, general somatic motor neurons such as the hypoglossal nucleus and spinal anterior horns, and other areas like the red nucleus and inferior olive. The inclusions were clearly shown with Nissl stain to be anilinophilic irregular masses with distinct rims. Ultrastructurally the inclusions appeared to consist of thick filamentous structures of 12–25 nm in diameter studded with electron-dense ribosomelike granules. Thick filamentous profiles were relatively short or occasionally fragmentary, haphazardly mingled with various amounts of granules and other organelles. No prominent accumulation of 10-nm neurofilaments or eosinophilic inclusions like Bunina bodies were found. The inclusions were indistinguishable from those reported in so-called “juvenile” amyotrophic lateral sclerosis.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-0533
    Schlagwort(e): Amyotrophic lateral sclerosis ; Guam ; Ubiquitin ; Immunohistochemistry ; Anterior horn cell
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Immunohistochemical studies with an antibody to ubiquitin revealed the presence of filamentous inclusions in spinal anterior horn cells in all of six patients with Guamanian amyotrophic lateral sclerosis (ALS) and one of six cases of parkinsonism-dementia complex (PD) on Guam. Similar ubiquitin-reactive filamentous inclusions were found in all of seven non-Guamanian sporadic ALS patients examined. No similar inclusions were seen in six normal controls or in non-ALS patients who had chromatolytic neurons. The filamentous inclusions differed from spinal neurofibrillary tangles, a characteristic feature of Guamanian ALS and PD, since they were restricted to anterior horn cells and did not react with anti-tau antibody. The chromatolytic neurons of non-ALS patients occasionally had weak diffuse immunoreactivity, but no focal inclusions were detected. These results suggest that ubiquitin-reactive focal filamentous inclusions may reflect a characteristic degenerative process of anterior horn cells of motor neuron disease.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-0533
    Schlagwort(e): Met-Enkephalin ; Alzheimer's disease ; Progressive supranuclear palsy ; Striatum ; Globus pallidus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Using a sensitive immunoperoxidase technique we examined Met-enkephalin (MEnk) expression in the striatum and globus pallidus external segment (GPe) from patients with Alzheimer's disease (AD) and with progressive supranuclear palsy (PSP). In AD patients strong MEnk-like immunoreactivity was persistent in the striatum showing so-called “striosomes”. In addition, a number of typical “woolly fibers” were observed in the GPe. MEnk-positive striosomes were also visible in the striatum of PSP patients and were similar to those of normal controls and of AD patients. However, the MEnk-positive “woolly fibers” appcarance was less well recognizable in the GPe from all the PSP patients examined.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Child's nervous system 6 (1990), S. 86-91 
    ISSN: 1433-0350
    Schlagwort(e): Congenital brain tumor ; Japanese infants ; Specific clinical features ; Prognosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The authors present specific clinical features of brain tumors occurring in immature brain in comparison with those of older infants and children. Twenty-six neonatal brain tumors, which accounted for 11.3% of 231 brain tumors diagnosed in the 1st year of life collected in a cooperative study in Japan, were analyzed. Although astrocytomas were invariably common tumors in each age group, comprising 25.0% for all pediatric brain tumors, teratomas were the most common type of neonatal brain tumors and accounted for 33.4% in this age group. Location of tumors in the immature brain was more striking, involving the posterior fossa region less commonly, as in 11.1% in neonatal, 29.5% in infantile, and 41.4% in all pediatric age groups. Surgical intervention was performed in 97.4% of the infantile and 79.1% of the neonatal cases, but total or subtotal resection of the mass was achieved only in 58.9% in the infants and 73.7% in the neonates. There was more strict limitation in performing the adjuvant therapies in the immature age groups. Radiation therapy and chemotherapy were given only in 32.0% and 27.6%, respectively, in the neonatal cases. The prognosis was extremely poor in the immature cases: 1-year, 5-year, and 10-year survivial rates were 59.3%, 26.1%, 11.5% in the infants, and 43.5%, 23.8%, 7.1% in the neonates, respectively. Of the neonates, 76% and of the infants 73.1% were retarded. The present study delineates the characteristic clinical features of tumors involving immature brain and emphasized that establishment of more specific therapeutic modalities is urgent.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1433-0350
    Schlagwort(e): Tethered cord syndrome ; Low-placed conus medullaris ; Myeloschisis ; Lipomeningocele ; Magnetic resonance imaging ; Over-distended spinal cord
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We present findings obtained from a total of 100 patients who had previously undergone surgery for spina bifida and whose progress had been monitored by magnetic resonance imaging (MRI) in our meningomyelocele clinic. Fourteen of these patients (14.0%) developed delayed symptom(s) of progressive spinal neurologic dysfunction. In those with myeloschisis, increase of motor deficit was the most common clinical manifestation during infancy and early childhood (mean age: 6.8 years), whereas pain on back flexion was seen in patients who were over 15 years of age (mean age: 17.3 years). MRI carried out in myeloschisis patients invariably demonstrated that the conus medullaris was in an abnormally low position, suggesting over-distension of the spinal cord. This was irrespective of whether symptom(s) developed or not and did not correlate with the initial surgical procedure (reconstructive or otherwise) used. Patients with symptom(s) were revealed by MRI to have an extremely low conus set at the spinal level of S-1 or below; neurological examination showed that the motor deficit occurred at high levels in the spine. Results from lipomeningocele patients were more erratic in terms of conus position and delayed development of neurological defects. The authors conclude: (1) that elongation of the spinal cord as an MRI finding seen postoperatively in cases of myeloschisis (radiological finding of a low-placed concus medullaris) does not necessarily imply functional disorder (tethered cord syndrome) and (2) that the pathophysiology of the late onset of progressive neurological deterioration in the spine occurring in patients who have previously undergone lipomeningocele repair may be associated with an invasive or expansile mass effect and should not always be regarded as involving tethered cord syndrome.
    Materialart: Digitale Medien
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  • 9
    ISSN: 1433-0350
    Schlagwort(e): Ependymoma ; Ependymoblastoma ; Infancy ; First year of life
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract During 1987, 23 survey forms for ependymoma cases diagnosed in the 1st year of life were selected from 88 neurosurgical institutes in Japan in collaboration with the International Society for Pediatric Neurosurgery. There were no specific perinatal episodes. The most common clinical manifestations were symptoms of intracranial hypertension and hydrocephalus. Two of seven children with infratentorial ependymomas were alive, and all of the children with such supratentorial tumors were still alive. Of those with ependymoma, three of four in the total extirpation group, and three of seven in the subtotal or partial removal group were alive. The 1-year survival rate was 54% for ependymoma and 58.3% for ependymoblastoma. For 36% of the cases with ependymoma and 14.6% with ependymoblastoma, a 2-year survival rate was observed. Since the prognosis of these tumors is poor, they should be extirpated as often as possible. Collins' law held true in approximately half of the cases.
    Materialart: Digitale Medien
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  • 10
    ISSN: 1433-0350
    Schlagwort(e): Brain tumors ; Neonates and infants ; Cooperative survey ; Far-Eastern countries ; Racial differences ; Congenital factors
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract A statistical survey is presented of brain tumors diagnosed in the first year of life (from five Far-Eastern countries) in relation to the racial differences in tumor types, congenital factors, and general clinical features. Of the 307 cases collected, 262 were verified histologically, and astrocytomas comprised 23.3%, medulloblastomas 17.2%, ependymomas 11.1%, choroid plexus papillomas 10.7%, teratomas 8.4%, primitive neuroectodermal tumors 4.2%, meningiomas 2.3%, and others 22.9%. There were statistically significant racial differences in comparison with the worldwide survey done by the International Society for Pediatric Neurosurgery Education Committee (1987) on the same subject. In the Far-Eastern population, medulloblastoma and teratoma were more common (P〈0.05), whereas astrocytoma was less frequent (P〈0.01) than reported in the worldwide survey. The malformative factors were suggested in 18 cases in which various associated congential anomalies were observed. Vascular anomalous lesions, mostly in the extracranial organs, were most common, comprising 61.1% of the associated malformations. Hereditary factors were less commonly demonstrated in these tumors than were anomalies in the major congenital central nervous system. Among the 307 cases, there was one instance (0.3%) of nearly identical tumors occurring in twin brothers. The specific clinical manifestations of brain tumors involving the immature brain were again apparent in this survey, as were the poor survival rates and poor functional prognosis.
    Materialart: Digitale Medien
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