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  • Wildau : TH  (49)
  • Springer  (24)
  • Münster: Westfälische Wilhelms-Universität Münster, Institut für Organisationsökonomik  (5)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Der Ophthalmologe 94 (1997), S. 16-19 
    ISSN: 1433-0423
    Keywords: Key words Cataract surgery ; Induced astigmatism ; Videokeratoscopy ; Schlüsselwörter Kataraktchirurgie ; Astigmatismusinduktion ; Videokeratoskopie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Die sklerale Tunnelinzision bei 12 Uhr zur nahtlosen Kataraktchirurgie führt durch eine Abflachung des vertikalen Hornhautmeridians zu einer Zunahme eines vorbestehenden Astigmatismus gegen die Regel. Eine schräge Achslage kann sich operativ induziert erheblich ändern. In einer prospektiven Studie sollte untersucht werden, ob durch die Verlagerung des Tunnelschnitts auf den steileren Hornhautmeridian in solchen Fällen eine Reduktion des Astigmatismus erzielt werden kann. 18 Augen mit seniler Katarakt und einem Astigmatismus gegen die Regel oder mit schräger Achslage von mindestens 0,7 dpt wurden standardisiert über einen 5×6 mm2 skleralen Tunnelschnitt mit einer 6 mm-PMMA-Hinterkammerlinse versorgt. Präoperativ und mittlere 6 Monate postoperativ wurde der Astigmatismus mit dem Videokeratoskop TMS-I bestimmt. Der absolute korneale Astigmatismus betrug präoperativ mittlere 1,8 und postoperativ 1,5 dpt. In 72% der Fälle war eine Verringerung der Astigmatismushöhe erzielt worden, in 17% blieb der Astigmatismus unverändert. Die operative Astigmatismusinduktion nach der Vektormethode von Jaffe und Clayman betrug durchschnittlich 0,68 dpt. Die Technik der skleralen Tunnelinzision mit lateralem oder schrägem Zugang ist geeignet, einen vorbestehenden Astigmatismus gegen die Regel oder mit schräger Achslage zu reduzieren.
    Notes: Scleral tunnel incision at the 12 o'clock-position for no-stitch cataract surgery can increase preexisting against-the-rule astigmatism by flattening the vertical corneal meridian. An oblique axis can change by operative induction. We investigated, in a prospective study, whether reduction of such a preoperative astigmatism could be induced by locating the tunnel incision on the steeper meridian. Eighteen eyes with senile cataract and against-the-rule or oblique astigmatism of at least 0.7 diopters were operated with a standardized 5×6 mm scleral tunnel incision and a 6 mm PMMA posterior chamber lens. We evaluated the astigmatism with a videokeratoscope TMS-I preoperatively and about 6 months after the surgery. The mean corneal astigmatism was 1.8 diopters pre- and 1.5 diopters postoperatively. A reduction of keratometric astigmatism was reached in 72% of cases; 17% remained unchanged. The surgically induced astigmatism calculated by Jaffe's and Clayman's vector analysis was 0.68 diopters. The technique of scleral tunnel incision with lateral or oblique approach can reduce a preexisting against-the-rule or oblique astigmatism.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Standort 21 (1997), S. 24-30 
    ISSN: 1432-220X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography
    Notes: Rund drei Viertel des Güterverkehrsaufkommens der Bundesrepublik Deutschland entfallen auf den Nahbereich bis 50 km. Davon werden 95% auf der Straße und nur 4% auf der Schiene transportiert. (Bundesminister für Verkehr 1995). Die zunehmende räumliche sowie funktionale Arbeitsteilung hat in den Städten und Gemeinden zu einem erhöhten Transportbedarf bei der Verteilung der Güter an die Endverbraucher geführt. Probleme und Belastungen treten insbesondere durch den Straßengüterverkehr auf. Ausgelöst durch Prognosen über die zukünftige Entwicklung des Güterverkehrs – u.a. als Folge der Liberalisierung des Europäischen Binnenmarktes – wird in letzter Zeit zunehmend die Verlagerung von Gütern auf die Bahn gefördert. Um die Belastungsspitzen auf kommunaler Ebene zu reduzieren, sind regionale Konzepte notwendig. Beispielhaft wird hierzu die derzeitige Situation des Güterverkehrs in der Region Bonn/Rhein-Sieg sowie die Planung und Umsetzung des Güterverkehrs auf der Schiene unter konkreter Einbeziehung der Industriebahn Bonn-Beuel dargestellt.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Monatshefte für Chemie 119 (1988), S. 781-791 
    ISSN: 1434-4475
    Keywords: Pyrano[3,2-c]quinoline-alkaloids ; 4-Hydroxyquinoline-2-ones ; Alkylation ; Phase-transfer-catalysis ; Sigmatropic rearrangement ; “Späth type” chromene synthesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The pyrano-cyclisation of 4-hydroxy-(1-methyl)-1H-quinoline-2-one with 3-chlor-3-methylbut-1-yne, supposed to proceed via an ether or vinyl intermediate, is studied by alkylating different 4-hydroxyquinolines. The nine derivatives characterized favour the ether-pathway (“Späth type” chromene synthesis).
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    ISSN: 1573-8744
    Keywords: carrier-mediated transport ; organic cations ; cationic drugs ; hepatobiliary elimination ; hepatic distribution ; drug interactions ; structure-pharmacokinetic relationship ; multiplicity in carrier proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Carrier-mediated transport of drugs occurs in various tissues in the body and may largely affect the rate of distribution and elimination. Saturable translocation mechanisms allowing competitive interactions have been identified in the kidneys (tubular secretion), mucosal cells in the gut (intestinal absorption and secretion), choroid plexus (removal of drug from the cerebrospinal fluid), and liver (hepatobiliary excretion). Drugs with quaternary and tertiary amine groups represent the large category of organic cations that can be transported via such mechanisms. The hepatic and to a lesser extent the intestinal cation carrier systems preferentially recognize relatively large molecular weight amphipathic compounds. In the case of multivalent cationic drugs, efficient transport only occurs if large hydrophobic ring structures provide a sufficient lipophilicity-hydrophilicity balance within the drug molecule. At least two separate carrier systems for hepatic uptake of organic cations have been identified through kinetic and photoaffinity labeling studies. In addition absorptive endocytosis may play a role that along with proton-antiport systems and membrane potential driven transport may lead to intracellular sequestration in lysosomes and mitochondria. Concentration gradients of inorganic ions may represent the driving forces for hepatic uptake and biliary excretion of drugs. Recent studies that aim to the identification of potential membrane carrier proteins indicate multiple carriers for organic anions, cations, and uncharged compounds with molecular weights around 50,000 Da. They may represent a family of closely related proteins exhibiting overlapping substrate specificity or, alternatively, an aspecific transport system that mediates translocation of various forms of drugs coupled with inorganic ions. Consequently, extensive pharmacokinetic interactions can be anticipated at the level of uptake and secretion of drugs regardless of their charge.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Review of industrial organization 5 (1990), S. 25-43 
    ISSN: 1573-7160
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract The survivor test to determine scale economies in an industry is applied to the U.S. petroleum refining industry. A time series covering every refinery for the period 1947–1984 is used. The results support Stigler's original conclusion of a saucer-shaped long-run average cost curve when his technique is duplicated on the full time series. However, we argue that the technique is misleading and try an alternative method which concludes that costs are decreasing for large scale refineries.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    JBIC 3 (1998), S. 96-106 
    ISSN: 1432-1327
    Keywords: Key words Dinuclear iron complexes ; Non-heme iron complexes ; Mössbauer spectroscopy ; Mixed-valent iron complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract  The asymmetrically coordinated complex [{L(Ph2acac)FeIII}(μ-O){FeIII(Cl4-cat)L}](BPh4)·1.5toluene has been synthesized and structurally characterized (Ph2acac–=1,3-diphenylpropane-1,3-dionate, Cl4-cat2–=tetrachlorocatecholate, L=1,4,7-trimethyl-1,4,7-triazacyclononane). This species can be electrochemically oxidized and reduced by one electron, respectively, yielding two species which both have an S=1/2 ground state. It is shown that the oxidation is ligand-centered, affording a coordinated semiquinonate(1–) ligand with S=1/2 which is antiferromagnetically coupled to a high-spin FeIII ion (S=5/2) yielding an S=2 state which, in turn, is antiferromagnetically coupled (through the oxo bridge) to the second high-spin FeIII ion (S=5/2) yielding the observed S=1/2 ground state. In contrast, the reduction is metal-centered generating a mixed-valent species with an [FeIII-O-FeII]3+ core; intramolecular antiferromagnetic coupling again produces an S=1/2 ground state. The symmetrical complex [{LFeIII(Ph2acac)}2(μ-O)](ClO4)2 has also been synthesized, as have the mononuclear species [LFeII(Ph2acac)Cl] and [LFeIII(aacac)Cl](ClO4)·1 mesitylene [aacac–=3-(9-anthryl)acetylacetonate(1–)], all of which have been characterized by X-ray crystallography. The magnetism, the Mössbauer-, EPR-, and UV-VIS-spectra and the electrochemistry of complexes are reported.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Planta 148 (1980), S. 444-447 
    ISSN: 1432-2048
    Keywords: Cell cultures ; Chlorophyll protein ; Photosynthesis (light harvesting) ; Poly(A)RNA ; Thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In thylakoid membranes isolated from green plants of parsley, pea, and barley, the light-harvesting chlorophyll a/b protein complex (LHCP, mol. weight: 25,000), is a major constituent. Poly(A)RNA isolated from these species was translated in a wheat germ, cell-free system. The in vitro translation products were treated with antibodies raised against the LHCP. This treatment resulted in the precipitation of a precursor protein (mol. weight: 29,000). Poly(A)RNA was also prepared from a cell culture ofPetroselinum that does not develop chloroplasts upon illumination. This poly(A)RNA is capable of stimulating amino acid incorporation in the in vitro translation system, however, it does not direct the synthesis of LHCP.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 422 (1993), S. 418-423 
    ISSN: 1432-2013
    Keywords: Neurodegeneration ; Plasticity ; Dendritic spines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We have developed an in vitro model of chronic epilepsy in order to study the consequences of prolonged periods of epileptic activity. After applying the convulsants bicuculline and/or picrotoxin to mature rat hippocampal slice cultures for 3 days, large numbers of swollen and vacuolated cells were observed throughout all hippocampal subfields. The number of dendritic spines of pyramidal cells was massively reduced. These changes were similar to those observed previously in post-mortem studies of hippocampal tissue from human epilepsy patients. Intracellular recordings from CA3 pyramidal cells revealed that spontaneous synaptic activity was greatly reduced in treated cultures. γ-Aminobutyric acid-mediated inhibition was apparently not affected by sustained convulsant activity, although synaptic excitation was markedly depressed. Acute re-application of bicuculline to treated cultures elicited, upon stimulation of the mossy fibre tract, a typical interictal burst lasting several hundred milliseconds, with a wave form similar to those occurring in untreated cultures, but of a shorter duration. In contrast, ictal bursts (lasting tens of seconds), which always occur spontaneously in control cultures during initial perfusion of bicuculline, were not observed in treated cultures. These pathological changes were reversible when treated cultures were returned to normal medium for 1 week. The surviving cells had a healthy morphology and a normal complement of dendritic spines. Spontaneous synaptic activity was normal, and ictal bursts occurred spontaneously upon perfusion of bicuculline. The findings suggest that the morphological and functional changes are a consequence, rather than a direct cause of epilepsy.
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Planta 148 (1980), S. 448-452 
    ISSN: 1432-2048
    Keywords: Chlorophyll protein ; Hordeum ; Photosynthesis (light harvesting) ; Poly(A)RNA ; Polysomes ; Thylakoid membranes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Polysomes from dark-grown and illuminated barley seedlings were translated in cell-free systems. The translation products reacting with the antibody against the light-harvesting chlorophyll a/b protein (LHCP) were analyzed by polyacrylamide gel electrophoresis. It was found that, in addition to the precursor protein of LHCP, a product was obtained that co-migrated with the mature protein. Furthermore, the results show that the light-induced proly(A)RNA for LHCP is integrated into the polysomal complex without delay, indicating that the integration of LHCP into the membrane is controlled at a higher level of gene expression.
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