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  • 1
    Electronic Resource
    Electronic Resource
    Valence bands of poly(methylmethacrylate) and photoion emission in vacuum ultraviolet region (1992)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 72 (1992), S. 5423-5428 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Photoion and photoelectron yields were measured for poly(methylmethacrylate) in the photon energy region of 8–40 eV using synchrotron radiation. Further, the valence-band structure was investigated with ultraviolet photoelectron spectra and valence effective Hamiltonian calculations. A significant difference was observed between the photon energy dependencies of photoion and photoelectron yields. The threshold energy for photoion emission was found to be 10.5 eV, while that for photoelectron emission was 8.5 eV, indicating holes created near the valence-band top do not contribute to the ion emission. At the higher-energy region, the ion emission efficiency was found to be enhanced in the photon energy region of 17–28 eV. The difference between the threshold energies of photoion and photoelectron emission and the enhancement of the photoion emission are discussed in conjunction with the valence-band structure.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.351983
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  • 2
    Electronic Resource
    Electronic Resource
    Enrichment of 13C by IRMPD of CBr2F2 (1991)
    Springer
    Applied physics 52 (1991), S. 266-272 
    Details
    ISSN: 1432-0649
    Keywords: 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The CO2-laser-induced infrared multiple photon decomposition of natural CBr2F2 in the presence of oxygen has been examined as a function of pulse number (30–1500), reactant pressures (CBr2F2, 10–150 Torr and O2, 5–90 Torr), laser line [9P(8)–9P(32)], and laser fluence (1–3 J cm−2) to optimize irradiation conditions for 13C-enrichment. CF2O was the main carbon containing product and afterwards was converted into CO2 via hydrolysis. A small amount of C2Br2F4 was detected only under extreme conditions, for example, at high laser fluences or wavenumbers close to an absorption band. The 13C-atom fraction of the final product CO2 was found to be 20–80%, depending on experimental conditions. The two-stage IRMPD process proposed previously has been examined in further detail in the present study. First, CBr2F2 containing about 30% of 13C was prepared in the 13C-selective IRMPD of natural CHClF2 in the presence of Br2. The second-stage IRMPD of the CBr2F2 in the presence of oxygen under selected conditions resulted in the high enrichment of 13C beyond 90%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325403
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  • 3
    Electronic Resource
    Electronic Resource
    13C-selective two-stage IRMPD of mixtures of CHClF2 and HI (1990)
    Springer
    Applied physics 50 (1990), S. 385-392 
    Details
    ISSN: 1432-0649
    Keywords: 82.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The 13C-selective infrared multiple-photon decomposition (IRMPD) of mixtures of CHClF2 and HI was examined in collimated and focused beam geometries using a CO2TEA laser. The carbon-containing products were CH2F2 and CHF2I. The former product showed remarkably high 13C atom concentrations beyond 95% under selected experimental conditions, while the latter contained 25% or less. The observed results can be explained satisfactorily in terms of the consecutive two-stage IRMPD process occurring in a single irradiation procedure, where the first-stage IRMPD of natural CHClF2 produces 13C-enriched CHF2I via the insertion of the initial decomposition fragment CF2 into HI, and the second stage is the subsequent 13C-selective IRMPD of the CHF2I to form a CHF2 radical and an I atom. The CHF2 radical reacts with HI to form CH2F2. Decomposition probabilities of 12CHClF2 and 13CHClF2 were measured as a function of laser fluence to optimize enrichment conditions. Furthermore, partial decomposition probabilities or relative production yields were measured as functions of laser line, pressure of HI, and pressure of CHClF2. Both stages showed high 13C selectivities in the irradiation with the laser radiation around 1040 cm−1 and at fluences below 4 J cm−2. This mixture is one of the most promising chemical systems for the production of highly enriched 13C.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00325091
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  • 4
    Electronic Resource
    Electronic Resource
    Endothelin causes contraction of canine and bovine arterial smooth muscle in vitro and in vivo (1990)
    Springer
    Acta neurochirurgica 104 (1990), S. 42-47 
    Details
    ISSN: 0942-0940
    Keywords: Endothelin ; neuropeptide Y ; angiotensin II ; cerebral arteries ; cerebral circulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We have studied the effect of endothelin, an endothelium-derived peptide, on isolated canine and bovine cerebral arteries in vitro and on canine vertebral blood flow (VBF) in vivo. Endothelin produced a dose-dependent contraction of canine and bovine arterial smooth muscle with ED50 values ranging from 4 to 8 nM. The response to endothelin developed slowly and persisted as a sustained contraction. Maximal contraction by endothelin required the presence of extracellular calcium and was independent of the presence of endothelium. The maximal contraction produced by endothelin was approximately 2–3 times greater than that produced by neuropeptide Y or angiotensin II. The injection of endothelin into the vertebral artery decreased vertebral blood flow (VBF) dose-dependently without affecting systemic blood pressure or heart rate. The decrease in VBF produced by endothelin was long-lasting, like that produced by neuropeptide Y, but more potent. The present data, together with our previous study demonstrating that the intracisternal injection of endothelin induces an unusually long-lasting decrease in the basilar artery diameter angiographically, suggests that endothelin may act as a long-acting vasoconstrictor in cerebral vascular disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01842892
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  • 5
    Electronic Resource
    Electronic Resource
    Prognosis of intracranial germ cell tumours: Effectiveness of chemotherapy with cisplatin and etoposide (CDDP and VP-16) (1993)
    Springer
    Acta neurochirurgica 120 (1993), S. 111-117 
    Details
    ISSN: 0942-0940
    Keywords: Germ cell tumour ; chemotherapy ; CDDP ; VP-16
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A co-operative study for patients with intracranial germ cell tumours was performed to analyze their prognosis and the effectiveness of Cisplatin/Etoposide (CDDP/VP-16) chemotherapy. A total of 46 patients; 30 primary and 16 recurrent cases were registered from 15 participating neurosurgical institutions in Japan. Based on histological criteria and tumour markers, they were classified into three groups; germinoma, germinoma with syncytiotro-phoblastic giant cell (STGC), and non-germinomatous malignant tumour. Sixteen patients were treated with CDDP/VP-16 chemotherapy alone and the other 30 patients were treated by a combination of surgery and/or radiation in addition to chemotherapy. Eleven out of 13 patients (85%) with germinoma showed a complete (n=10) or partial (n=1) response to CDDP/VP-16 chemotherapy even if their tumours were recurrent and there was evidence of CSF dissemination. For the germinoma with STGC and non-germinomatous malignant tumour, a high response rate; 100% for the former and 78% for the latter, could also be achieved in both the primary and the recurrent cases except in those cases of immature teratoma. Their survival times were still different between them. Two-year survival was 50% in germinoma with STGC and 48% in non-germinoma, while it was 88% in germinoma cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02112027
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  • 6
    Electronic Resource
    Electronic Resource
    Long-term follow-up results of 175 patients with malignant glioma: Importance of radical tumour resection and postoperative adjuvant therapy with interferon, ACNU and radiation (1994)
    Springer
    Acta neurochirurgica 127 (1994), S. 55-59 
    Details
    ISSN: 0942-0940
    Keywords: Malignant glioma ; interferon ; nitrosourea ; radiotherapy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We analysed long-term follow-up results of 175 patients with malignant glioma (110 glioblastoma and 65 anaplastic astrocytoma) treated under five different regimes during the past two decades. The factors of age (less than 40), histology (anaplastic astrocytoma) and type of adjuvant therapy (radiation and chemotherapy) contributed to long survival. The other important factor was the response to adjuvant therapy. Cases of gross total removal or complete response (CR) of a residual tumour to an adjuvant therapy showed a better prognosis. The three and five year survival rate was 42% and 24%, respectively. The highest CR ratio (23%) was seen in patients treated by intravenous injection of interferon and ACNU in addition to radiotherapy (IAR therapy).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01808547
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  • 7
    Electronic Resource
    Electronic Resource
    Meningiomas: Correlation between MRI characteristics and operative findings including consistency (1994)
    Springer
    Acta neurochirurgica 129 (1994), S. 39-46 
    Details
    ISSN: 0942-0940
    Keywords: Tumour consistency ; meningiomas ; MRI ; T 2-weighted image
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The findings on magnetic resonance imaging (MRI) in 73 surgically verified intracranial meningiomas were correlated with their histology and consistency during resection. T 1-weighted imaging was least useful since most of the tumours were iso-intense, similar to cortical grey matter regardless of histology or tumour consistency. The signal intensity on T 2-weighted images was found to best correlate with both the histology and consistency of the meningioma. Generally, the low intensity portion of the tumour on T 2-weighted images indicated a more fibrous and harder character, while the higher intensity portions indicated a more soft character. Most of the fibroblastic meningiomas showed the features of a hard tumour while angioblastic tumours showed the features of soft tumours. Tumours predicted to be harder on MR imaging generally took longer to resect than softer ones, and this relationship was shown best for the larger tumours. Using linear regression analysis, it appears that operative time for soft tumours is more affected by factors other than tumour consistency. Blood loss during surgery was also unrelated to the consistency of the tumour. These results suggest that the histology and consistency of meningiomas may be predictable from findings on T 2-weighted imaging, and this may also predict the difficulty and time required for resection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01400871
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  • 8
    Electronic Resource
    Electronic Resource
    Dural arteriovenous malformations in the anterior cranial fossa (1994)
    Springer
    Acta neurochirurgica 129 (1994), S. 146-151 
    Details
    ISSN: 0942-0940
    Keywords: Anterior cranial fossa ; anterior ethmoidal artery ; dural arteriovenous malformation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Two cases of dural arteriovenous malformation (DAVM) fed by the anterior ethmoidal artery in the anterior cranial fossa are reported, one of them examined by magnet resonance imaging (MRI). Only one other case with MRI findings so far has been published. Fourty-eight previously reported cases are reviewed. One of our patients presented with subdural haematoma (SDH) without subarachnoid or intracerebral haemorrhage. The other patient had a nasal bleed without any neurological manifestations. In comparison with previously reported cases, the clinical manifestation of our cases is infrequent (1 patient with nasal bleed, and 2 patients with pure SDH that is 2 and 4%, respectively, in the literature). Feeder was the anterior ethmoidal artery either unilateral or bilateral. Drainage of DAVMs was through a markedly dilated vascular sac into the superior sagittal sinus (SSS). The high incidence of haemorrhage from DAVM in the anterior fossa is related to this vascular sac. Magnetic resonance imaging (MRI) showed a flow void area in the left frontal region on T 1-weighted images in one case. These cases were treated by surgical excision of the malformation with good results. Aetiology, clinical presentation, and treatment of these rare DAVMs in the anterior cranial fossa is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01406494
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  • 9
    Electronic Resource
    Electronic Resource
    A newly designed nerve monitor for microneurosurgery: Bipolar constant current nerve stimulator and movement detector with a pressure sensor (1993)
    Springer
    Acta neurochirurgica 125 (1993), S. 173-176 
    Details
    ISSN: 0942-0940
    Keywords: Acoustic tumour ; cranial nerve ; nerve monitor ; pressure sensor
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The authors describe a newly designed nerve monitor which is useful for numerous microneurosurgical procedures. Standard bipolar forceps are used to apply constant current stimulation. Muscle contraction evoked by the stimulation is detected by a small discshaped pressure sensor taped to the overlying skin. The responses are monitored both quantitatively on a liquid crystal display and qualitatively through an on-off auditory signal. Surgery can proceed without interruption. This apparatus can safely and reliably monitor the facial nerve, nerves involved in eye movements, lower cranial nerves and spinal nerves. This portable system weighs only 1.8 kg and can easily be used by a neurosurgeon.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01401847
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  • 10
    Electronic Resource
    Electronic Resource
    Normovolaemic induced hypertension therapy for cerebral vasospasm after subarachnoid haemorrhage (1990)
    Springer
    Acta neurochirurgica 103 (1990), S. 18-26 
    Details
    ISSN: 0942-0940
    Keywords: Cerebral vasospasm ; haemorrhagic infarction ; intracranial aneurysm ; normovolaemic induced hypertension therapy ; subarachnoid haemorrhage ; Swan-Ganz catheter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary We showed that normovolaemic induced hypertension therapy was effective in reducing ischaemic symptoms attributed to cerebral vasospasm in 41 patients after subarachnoid haemorrhage. By inducing hypertension to 25% to 50% above normal systolic arterial blood pressure, we observed that in 17 of 24 cases (71%) neurological deficits improved. In four cases of haemorrhagic infarction, the blood pressure rose to over 50% of systolic arterial pressure, and a low density area was confirmed on computerized tomography (CT) scan prior to vasospasm. Induced hypertension was therefore not considered when a low density area was revealed on CT scan. Restriction of fluid input is usually a factor in producing hypovolaemia after a neurosurgical operation. Intravascular volume expansion has been reported effective in reversing ischaemic deficits. However, according to Poiseuille's equation, increasing blood volume to a state of hypervolaemia can not enhance flow. The cerebral blood flow (CBF) was raised by increasing perfusion pressure, reducing viscosity, or increasing blood vessel diameter. Intravascular volume expansion elevates not only systemic arterial pressure, but also pulmonary artery wedge pressure over 18 mmHg and cardiac index over 2.2. Since pulmonary oedema and congestive heart failure may develop, one should monitor haemodynamic parameters with the Swan-Ganz catheter as a preventive measure. We emphasize that normovolaemic induced hypertension, maintaining haemodynamics subset 1 of the comparable haemodynamic subsets, is effective in raising perfusion pressure of CBF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01420187
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