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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Pure and applied geophysics 152 (1998), S. 539-550 
    ISSN: 1420-9136
    Keywords: Key words: Seismograph calibration, historical instruments, Wiechert seismograph.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract —The paper presents results of experiments designed to measure the actual dynamic magnification of the Wiechert 1000 kg horizontal seismometer when excited by seismic waves. This is accomplished by comparing 51 digital records of seismic events recorded by the Wiechert and a well calibrated reference seismometer. The results obtained indicate that the magnification of the Wiechert seismometer is influenced by the interaction of its mass and frame, especially for high frequencies. This interaction has been modeled by considering a system of two coupled pendulums, yielding a theoretical dynamic magnification curve which exhibits main features of the observed magnification. The dis crepancy between the nominal and the actual response of the Wiechert seismograph may lead to errors in studies involving spectral analyses of recorded seismograms, and to overestimation of local earth quake magnitudes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-055X
    Keywords: Schlüsselwörter Swan-Ganz-Katheter ; Komplikation ; Nahtfixation ; Pulmonalarterie ; Key words Swan-Ganz catheter ; Complication ; Suture fixation ; Pulmonary artery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Abstract We report a patient undergoing redo cardiac surgery for combined replacement of the aortic and mitral valves. During the course of the operation, a Swan-Ganz catheter – positioned preoperatively – was accidentally fixed to the wall of the pulmonary artery. As this did not interfere with cardiac output measurement or the pulmonary artery pressure wave form, the fixation was not noticed until an attempt was made to remove the catheter. Fluoroscopy revealed both the catheter's immobility and the location of the suture fixation. The patient required a sternotomy to remove the catheter. In order to avoid this complication, the indications for pulmonary artery catheters during cardiac surgery should be carefully considered. If catheters are inserted, their mobility should by all means be ensured before the chest is closed.
    Notes: Zusammenfassung Der vorliegende Fallbericht beschreibt die Nahtfixation eines Swan-Ganz-Katheters in der A. pulmonalis während eines kombinierten Aorten- und Mitralklappenersatzes. Da die Funktionen des Katheters nicht eingeschränkt waren, blieb die Fixation bis zur beabsichtigten Katheterentfernung unbemerkt. Konventionelle Röntgenaufnahmen legten die Diagnose nahe. Die Katheterentfernung erfolgte operativ über eine Resternotomie des Patienten. Zur Vermeidung dieser Komplikation bei kardiochirurgischen Eingriffen sollte, neben einer strengen Indikationsstellung, vor Thoraxverschluß in jedem Fall die freie Beweglichkeit sämtlicher Katheter im Operationsgebiet geprüft werden.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1084
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Extraction of stones from the bile ducts via standard endoscopic techniques, a percutaneous transhepatic approach, or a T-tube track can be unsuccessful. We report our preliminary experience with a combination of percutaneous cholangioscopy and dye laser lithotripsy. Flash lamp-excited dye laser (504 nm) lithotripsy delivered by percutaneous cholangioscopy (12 F) was evaluated in 13 patients with stones in the bile ducts. Conventional endoscopic treatment had not been attempted in 4 patients after hepaticojejunostomy and had failed in 3 patients after gastric bypass surgery or gastrectomy, and in 6 patients because of technical difficulties, i. e. due mainly to largeness of stones. In 12 patients a percutaneous transhepatic route was used. In 1 patient the T-tube track was used as access to the bile ducts. Laser lithotripsy resulted in successful fragmentation of stones in 12 patients (92%). The bile ducts cleared spontaneously in 2 patients only. Using additional techniques, i. e. sphincterotomy and stent insertion, the overall combined success rate for duct clearance after laser fragmentation was 100%. Four patients had a retrograde endoscopic sphincterotomy after failed attempts for stone removal at endoscopic retrograde cholangioscopy. Two patients had an antegrade fluoroscopically monitored sphincterotomy. Bleeding complications occured in 2 patients. This accounted for a high rate (15%) of severe complications. The intrahepatic bleeding in 1 patient was due to an intrahepatic vessel injury by the 13-F sheath. The periampullary bleeding in the other patient occurred after an antegrade papillotomy. Pulsed dye laser lithotripsy proved to be an effective technique in patients with difficult bile duct stones. The main problem of a percutaneous approach is the complete removal of the fragmented stones, which requires additional procedures in most cases. The percutaneous access is time-consuming and bears a relatively high risk of major bleeding complications. It should therefore be restricted to cases in which conventional endoscopic procedures are impossible or unsuccessful.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1084
    Keywords: Arteries, extremities ; Arteries, laser angioplasty ; Arteries, transluminal angioplasty ; Lasers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated a pulsed 504 nm dye laser at a pulse duration of 1.44 μ and a pulse rate of 10 Hz for its angioplasty capabilities. Laser energy was delivered via 9 F multi-fiber ring catheters. Our experimental data showed effective ablation of atheroma and disruption of calcified plaques at an energy fluence of 9.5 J/cm2 under saline and blood. Histologically, there was only minimal thermal injury to adjacent tissues. Irregular tissue borders after radiant energy exposure of 12.7 J/cm2, under blood, provide strong evidence for ablation by a shock-or pressure-wave mechanism. Percutaneous peripheral laser-assisted angioplasty was performed in 25 patients with arterial occlusive disease of the iliac and femoro-poplteal arteries (mean occlusion length 7.2 cm). All lesions were initially traversed by a guide-wire. Technical success was achieved in 24 out of 25 patients (96%). Laser angioplasty decreased the mean stenosis rate from 100% to 51± 12% (P 〈 0.01). The ankle-brachial index (ABI) rose from 0.48±0.16 before to 0.88±0.10 after intervention (P 〈 0.01) with a value of 0.82±0.15 at 6 months follow-up. The overall success rate, judged clinically and by ABI determinations in all patients, was 84% at a mean follow-up period of 7.9 months. The number of stand-alone laser procedure was 21%. Clinical application of the delivery devices proved to be safe due to the “over-the-wire” approach. Our prelimanary clinical data encourage further refinement of pulsed dye laser angioplasty for more efficacious debulking of atheroma.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 8 (1960), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: In some mines of the Siegerland, besides dilatational and shear waves, an additional direct wave has sometimes been found the velocity of which was somewhat lower than that of the shear wave. Investigations were carried out with the object to establish the directions of oscillations and the velocities of all three kinds of waves. It was the purpose to draw conclusions as to the character and the causes of the appearence of the third wave.By these investigations the wave having the lowest velocity can be identified as a second shear wave. This points to the fact that double refraction of the shear wave is taking place, the wave of higher velocity being a pure transverse wave and the wave of lower velocity being a quasi-transverse wave.As a result of these measurements the examined medium is shown to have a transverse isotropy due to stratification. It is, however, not possible to decide whether there exists also an anisotropy due to schistosity.Some further calculations show that the wave of lowest velocity can not be explained as a surface wave propagated on the walls of the gallery.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Der Chirurg 71 (2000), S. 182-188 
    ISSN: 1433-0385
    Keywords: Keywords: Bile ducts, injuries – Bile ducts, interventional procedure – Bile ducts, stenosis and obstruction – Bile ducts, stents and prostheses. ; Schlüsselwörter: Gallenwegverletzungen – Gallenwege, interventionelle Prozeduren – Gallenwege, Stenosen und Obstruktionen – Gallenwege, Stents und Prothesen.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Einleitung: Hohe benigne biliäre Stenosen, die durch einen komplizierten Krankheitsverlauf bedingt sind oder als Folge einer Operation auftreten, können Bedingungen vorgeben, die eine operative Revision erschweren oder ein hohes Operationsrisiko bedingen. Alternativen zur operativen Revision stellen die percutane Implantation von flexiblen Metallgitterstents oder das Einbringen von Silikonprothesen in das stenosierte Areal dar. Methoden: Seit März 1992 wurden in unserer Klinik 12 Patienten mit benignen Gallenwegstenosen behandelt, von denen 6 einen Palmazstent erhielten und 6 mittels einer Silikonprothese therapiert wurden. Der Erfolg dieser 2 Behandlungskonzepte wurde retrospektiv untersucht. Ergebnisse: Die Nachbeobachtungszeit nach Abschluß der Behandlung beträgt bei der Stentimplantation über 7 Jahre und bei der Behandlung mit einer Silikonprothese über 3 Jahre. 50 % der behandelten Patienten mit einem Stent hatten einen völlig unauffälligen Verlauf. Unter Berücksichtigung einer notwendigen interventionellen Revision lag die Offenheitsrate bei 66 %. Bei den mit einer Silikonprothese behandelten Patienten war während der Nachbeobachtungszeit bei keinem eine Revision erforderlich. Schlußfolgerung: Unter Berücksichtigung der Vor- und Nachteile der interventionellen Alternativen zur Operation stellt die prolongierte, großkalibrige Schienung benigner biliärer Stenosen mit Silikonprothesen (Yamakava) eine vielversprechende Therapieform dar.
    Notes: Abstract. Introduction: High benign biliary stenoses, which can occur as a complication of disease or surgery, may be difficult to correct by open surgery and may also carry a high risk. An alternative to surgery is the percutaneous implantation of a flexible metallic stent or silicon prosthesis at the affected site. Methods: Twelve patients with benign biliary stenoses have been operated on in our department since March 1992, and the therapeutic success was reviewed in this study. Results: Six received a Palmaz stent and six a silicon prosthesis, with a follow-up after completion of treatment of more than 7 years and more than 3 years, respectively. Fifty percent of the patients with a stent experienced no problems and 66 % of the stents remained patent (including one requiring operative intervention to restore patency). No further surgery was necessary in any of the patients with a silicon prosthesis. Conclusion: When the advantages and disadvantages of the various procedures are considered, long-term splinting with a wide-lumened silicon prosthesis (Yamakava) appears to be a promising alternative to surgery for the treatment of benign biliary stenosis.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1433-0385
    Keywords: Key words: Bile ducts ; injuries ; Bile ducts ; interventional procedure ; Bile ducts ; stenosis or obstruction ; Bile ducts ; stents and prostheses ; Schlüsselwörter: Gallenwegverletzungen ; Gallenwege ; interventionelle Prozeduren ; Gallenwege ; Stenosen und Obstruktionen ; Gallenwege ; Stents und Prothesen.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung. Ziel: Als Alternative zur operativen Revision einer hohen, benignen biliären Striktur soll das technische Vorgehen der großkalibrigen Gallengangschienung mit Yamakawa-Prothesen ohne repetitive Ballondilatation am Beispiel einer Patientin geschildert werden. Methoden: Zur Stenoseüberbrückung wurde bilateral eine percutan-transhepatische Anlage von 2 Yamakawa-Prothesen aus Silikon vorgenommen (Ductus hepaticus, rechts: 14-F-Prothese; links: 12-F-Prothese). Die Prothesen wurden unter permanentem oralen Antibioticaschutz alle 8 Wochen durch neue Prothesen ersetzt. Nach 8 Monaten wurden beide Prothesen entfernt. Ergebnisse: Die Kontroll-Cholangiographie zeigte ein normal-weites intrahepatisches Gallenwegsystem rechts und eine 50 %ige Mündungsstenose des linken Ductus hepaticus. Die Nachbeobachtung über einen Zeitraum von 18 Monaten zeigte keinen Hinweis auf eine Abflußbehinderung des Gallengangsystems. Schlußfolgerungen: Im Vergleich zur repetitiven Ballondilatation und zur Implantation metallischer Gallenwegstents bietet sich die prolongierte, großkalibrige Schienung benigner biliärer Strikturen mit Yamakawa-Prothesen als alternative Therapieform an.
    Notes: Summary. Aim: As an alternative method to the operative revision of benign bile duct strictures, we report the use of a large-bore bile duct prosthesis (Yamakawa prosthesis) in one patient. Methods: Bilateral percutaneous transhepatic implantation of Yamakawa prostheses (14 F right side, 12 F left side) was performed without adjunctive balloon dilatation. The prostheses were exchanged every 8 weeks under continuous antibiotic treatment and were finally removed after 8 months. Results: Control cholangiography showed a normal intrahepatic biliary system on the right side and a 50 % stenosis at the orifice of the left hepatic duct. Follow-up over 18 months showed no signs of recurrent disease. Conclusions: In comparison to balloon dilatation and implantation of metallic stents, prolonged bilateral splinting with large-bore Yamakawa prostheses seems to be an alternative for the treatment of benign bile duct strictures.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 372 (1987), S. 907-913 
    ISSN: 1435-2451
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Zusammenfassung Schon heute bietet die MRT gegenüber der CT in einigen Fragestellungen Vorteile. So gelingt in der Leber eine eindeutige Diagnose von Hämangiomen ohne Kontrastmittel. Metastasen sind in einer Fettleber und ein Leberzellcarcinom bei einer Lebercirrhose besser diagnostizierbar als mit den herkömmlichen bildgebenden Untersuchungsverfahren Ultraschall und CT. Die Konzentrationsfähigkeit der Gallenblase kann durch die MRT bestimmt werden. Die Abgrenzung des durchströmten Lumens vom Thrombus gelingt beim Aortenaneurysma in der MRT ohne Kontrastmittelapplikation. Der Nachweis eines Tumoreinbruches in die Vena renalis oder in die Vena cava inferior beim Hypernephrom gelingt ebenfalls ohne Kontrastmittel. Hämorrhagische oder infizierte Cysten können besser in der MRT als mit der CT differenziert werden. Die Differenzierung einer renalen Lipomatose gegenüber einer peripelvinen Cyste ist möglich. In der Nebenniere ist nach Reinig et al. ein Signalanstieg in T2 gewichteten Bildern ein charakteristisches Zeichen bei Phaeochromocytomen [31]. Bei Rectumcarcinomen kann die Infiltration in das perirectale Fett und in die umgebenden Organe mittels der MRT ebenfalls mit einer höheren Sicherheit als mit der CT erkannt werden. Zusammenfassend soll ergänzt werden, dass abdominelle Flüssigkeitsansammlungen wie z. B. Galle, Ascites, Cysten und Blut mit der MRT besser klassifiziert werden können als mit der CT. Fettreiche Gewebe und Hämatome zeigen einen typischen Signalanstieg in T1-betonten Bildern. Als wesentlicher Vorteil der MRT gegenüber der CT muss die Möglichkeit dreidimensionaler Darstellung angesehen werden. Aufgrund des grösseren Kontrastumfanges ist in der MRT eine bessere Weichteil-Gewebedifferenzierung möglich, und schliesslich gelingt die Darstellung und Abgrenzung von Gefässen z. B. von Lymphomen in der MRT ohne Kontrastmittelgabe.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0584
    Keywords: Leukemia ; Therapy control ; Hematopoietic bone marrow ; Magnetic resonance ; MR imaging ; MR chemical shift imaging ; MR1H localized spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Red bone marrow of healthy persons has considerable contents of water and lipids. The cellularity and the corresponding fat-water ratio within the marrow show clear changes in hematological diseases. Magnetic resonance (MR) methods use the signals of the protons of water and lipids. This paper gives a comparison between different standard MR techniques and recently developed fat- and water-selective imaging methods, addressing their sensitivity to bone marrow changes in leukemia. Additionally,1H results of spectroscopic methods are presented. The results and conclusions are based on the examination of 26 healthy volunteers and 106 patients with general or focal bone marrow alterations. Standard T1-weighted images did not distinguish bone marrow of young healthy volunteers with relatively high cellularity from acute leukemia. Using fat- and water-selective methods, patients with untreated leukemia showed only water proton signals and no lipid signals from red bone marrow of vertebral bodies and the pelvis. This phenomenon was never observed in healthy volunteers. Following chemotherapy, lipid and water contents normalize in successfully treated patients. Nonresponders did not show significant changes of the fat-water ratio after up to 3 weeks of therapy. Phase contrast imaging provides information about the difference between fat and water fractions within the bone marrow, but quantitative determination of the absolute fat and water fractions requires acquisition of several images and suffers from the susceptibility effects in trabecular bone marrow. The fat-water ratio and additional qualities of water and lipid protons (relaxation times) can be evaluated by volume-selective MR spectroscopy. Typical results of spectra from small-volume elements in hypercellular vertebral bone marrow of leukemic patients before cytotoxic treatment and of normocellular or hypocellular marrow after therapy are demonstrated.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1573-157X
    Keywords: P-wave spectra ; Magnitude ; Anelastic attenuation ; Calibrating functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Calibrating functions for determination of P-wave spectral magnitudes calculated by Duda and Yanovskaya (1994) on the basis of the IASP91 velocity model and the PREM Q-model are verified empirically. For this purpose IRIS broadband records for 120 earthquakes are used, each earthquake having been recorded at about 100 stations. The discrepancies indicate that anelastic absorption assumed in PREM is too high. New calibrating functions are calculated on the basis of the AK135 velocity and anelasticity models (Kennet et al., 1995; Montagner and Kennet, 1996), in which Q in the mantle is higher than in PREM. The verification of the new calibrating functions based on the same observations yields magnitude figures less depending on the epicentral distance. In addition the parameter τ2in the Liu-Anderson Q(T) model is estimated, proceeding from the assumption that on the average the radiated spectra comply with the ω2-model. The value of τ2 was assumed to be 0.1 s in the analysis and its use resulted in the verification of the ω2-model for the source spectrum.
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