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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Electrical engineering 59 (1977), S. 201-209 
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Contents A single-phase converter with high power factor and negligible reaction on the ac network is analysed whereby that good performance is obtained by a closed-loop control of the ac input current. Currents, frequencies and power factors are calculated under simplifying assumptions and described in diagrams.
    Notes: Übersicht Ein einphasiger Stromrichter wird analysiert, dessen netzseitiger Strom zur Erzielung geringer Netzrückwirkungen und eines hohen Leistungsfaktors sinusförmig und in Phase mit der Netzspannung geregelt wird. Interessierende Größen wie Ströme, Schaltfrequenzen und Leistungsfaktoren werden unter vereinfachenden Annahmen berechnet und in Diagrammen dargestellt.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1084
    Keywords: MRI ; MRA ; Meningiomas ; Arterial displacement ; Tumor-feeding vessels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A group of 41 patients with intracranial meningiomas were examined by MR imaging (MRI) and MR angiography (MRA) to assess the. clinical value of MRA in the preoperative evaluation of these patients. The results of MRA were compared with the results of intraarterial cerebral catheter X-ray angiography (XRA; n = 19) and with the operative findings (n = 41 ): Our results showed a good correlation between MRA and XRA/surgery in demonstrating the relationship between the tumor and adjacent venous and arterial structures. Use of MRA was also helpful in demonstrating the degree of intrinsic tumor vascularity. It also supplied important information for operative planning Adjunct XRA was mandatory if detailed information about tumor-feeding vessels was requested by the neurosurgeon, especially in highly vascularized angiomatous meningiomas and in meningiomas suspected of tumor feeding by vessels of the internal carotid artery.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    European radiology 4 (1994), S. 133-141 
    ISSN: 1432-1084
    Keywords: CSF flow ; Hydrocephalus ; MRI
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fifteen patients with solid and cystic occlusions of the cerebrospinal fluid (CSF) circulation pathways were examined with MRI using an ECG retrogated two-dimensional FISP sequence to determine whether there are certain defined pathological CSF flow patterns in these patients. All patients were clinically still compensated. The results of the measurements of CSF flow velocities at different locations in the CSF system were compared with the results from 8 healthy volunteers. In all patients with occlusive processes of the intraventricular CSF pathways (4 aqueduct stenoses, 1 membranous occlusion of the fourth ventricular outlets, 1 solid tumour at the foramen of Monro and 1 solid fourth ventricular tumour) we observed hyperdynamic CSF pulsation above the lesion. This was transmitted into the spinal canal. Close by a solid occlusion within the aqueduct the flow velocity curve over the RR cycle was typically shifted, resulting in a mirroring of the flow velocity curve compared with normals. In cystic lesions (n = 4) there was transmission of the pulsation wave through the lesion and therefore no mirroring of the flow velocity curve. This technique allows very good delineation of cystic structures in the peripineal region (n = 4), also due to the opposite direction of flow within the cyst compared with the surrounding CSF spaces, depending on the extent of communication.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0942-0940
    Keywords: Spondylodiscitis ; lumbar disc operation ; intraoperative contamination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In 412 patients undergoing surgery for herniated lumbar discs from September 1986 to September 1987 and from January 1988 to July 1989 a microbiological specimen was taken from the intervertebral disc space and from the cover of the operating microscope. Also the tips of the wound drains were examined microbiologically after removal. 17% of the patients had a positive bacteriological culture from their intervertebral disc space; 12% of the specimen from the operating microscope were positive. These results favour the hypothesis that intra-operative contamination of the disc space, in contrast to haematogeneous spread, causes spondylodiscitis. On the other hand we saw during this time course only one case of clinical spondylodiscitis, which implies a possible involvement of other predisposing factors such as pre- or perioperative infections or compromised patient immunologically. It is also possible, that the routine application of local antibiotic or antiseptic solutions into the disc space at the end of the operation could decontaminate the operative site and prevent clinical infection despite positive culture findings.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Psychiatry Research 29 (1989), S. 287-288 
    ISSN: 0165-1781
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Psychiatry Research 29 (1989), S. 283-284 
    ISSN: 0165-1781
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European spine journal 8 (1999), S. 218-222 
    ISSN: 1432-0932
    Keywords: Key words Lumbosacral extradural arachnoid cyst ; Low back pain ; MRI ; Cerebrospinal fluid flow
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract No critical discussion of the indication for the surgical treatment of lumbosacral extradural arachnoid cysts is found in the literature. Therefore, we want to compare the results in patients with operative and conservative treatment to define standards for a good surgical result. Over a period of 9 years, we operated on eight patients with a lumbosacral extradural arachnoid cyst and treated eight others conservatively. Only three of the operated patients experienced a postoperative relief of pain, but none was symptom free. The only one with continuing success had a preoperative history of 1 year only. MRI scans without contrast agent were misinterpreted in one included and one excluded case. The results of conservative treatment were nearly the same as those of operative treatment. MRI is the best diagnostic tool, but a variety of sequences must be used. Patients with a short pain history and a clear neurological deficit profited most from surgery. Patients with slight and not clearly related uncharacteristic symptoms should be excluded from surgery.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1433-044X
    Keywords: Schlüsselwörter: Epiduralhämatomen ; Paraparese ; Sinusverletzung ; Key words: Epidural haematoma ; Paraparesis ; Superior sagittal sinus laceration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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