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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 76 (1994), S. 4894-4896 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The dielectric function of thin-film hydrogenated amorphous silicon (a-Si:H) grown on fused silica at different substrate temperatures has been investigated by spectroscopic ellipsometry. An improved interpretation of the ellipsometric data is based on a tetrahedron model that takes into account the influence of hydrogen incorporation in the amorphous network. It is shown that the film density can be derived from an accurate data interpretation, whereas the maximum value of the imaginary part of the dielectric function ε2max and the void volume fraction are not proportional to the density of a-Si:H films.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 199-202 
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In this paper, a general method for generating quasiperiodic lattices is given. It is based on point multilattices which may be transformed into quasilattices in a new manner. A rounding operation allows the conversion of amassments of points in the multilattice into single points of a perfect quasicrystalline structure. Several examples are given.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of pineal research 14 (1993), S. 0 
    ISSN: 1600-079X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: The effect of exogenous melatonin on the adrenocortical axis was studied by determining serum corticosteroid and adrenocorticotrophic hormone (ACTH) levels under basal and stressed conditions in intact, pinealectomized, and adrenalectomized mature male rats. A direct interrelationship between pineal/melatonin and the adrenal cortex, dissociated from the hypothalamic-pituitary axis, was established. Intraperitoneal injection of 100 μg melatonin brought about an elevated adrenocortical response recorded in the serum corticosteroid levels 15 hr afterwards. This effect could be demonstrated only at the beginning of the photophase, when physiological levels of corticosteroids and ACTH are at their lowest daily levels. The pattern of this reaction is different from those caused by stressors such as ether or hypoglycemic reagents, and did not occur in pinealectomized animals although the daily rhythm of corticosteroids and ACTH persisted. No effect on ACTH was evident in intact or adrenalectomized rats, where the serum levels remained unchanged. Moreover, the corticotrophin releasing factor (CRF) content of the median eminence was not affected by melatonin.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Bundesgesundheitsblatt, Gesundheitsforschung, Gesundheitsschutz 42 (1999), S. 132-142 
    ISSN: 1437-1588
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary Since the publication of a case of Syphilis transmission by blood transfusion in 1915 the discussion about transfusion-associated bacterial infection is ongoing. For some time, virus infections through blood and blood products have been highlighted. However, in the last years the attention required has been drawn to the problem of transmission of bacteria. In this publication the present situation concerning the contamination rates through blood components and the frequency of transfusion-associated microbial infections is outlined. The bacteria involved are discussed. Furthermore, the state of the art for prevention and diagnosis as well as the methods for inactivation of bacteria are assessed.
    Notes: Zusammenfassung Seitdem im Jahre 1915 ein Fall von Syphilis-Übertragung durch Bluttransfusion publiziert wurde, ist die Diskussion um die transfusionsassoziierte bakterielle Infektion nicht mehr verstummt. Nachdem diese Problematik angesichts der Virusinfektionen durch Blut und Blutprodukte über einige Zeit etwas in den Hintergrund geraten war, erfuhr sie in der Literatur der letzten Jahre wieder die erforderliche Aufmerksamkeit. In dieser Arbeit wird die aktuelle Situation hinsichtlich der Kontaminationsraten von Blutkomponenten und der Häufigkeit von transfusionsbedingten bakteriellen Infektionen dargestellt. Das Spektrum der involvierten Keime wird diskutiert. Weiterhin werden die heutigen präventiven und diagnostischen Möglichkeiten sowie die Verfahren zur Inaktivierung von Bakterien einer kritischen Wertung unterzogen.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1435-1463
    Keywords: Melatonin ; oxazepam ; pinealectomy ; circadian ; diurnal ; brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Sham-operated and pinealectomized male rats were maintained at 14h light: 10 h dark cycles (lights-on 5.00 h) and injected daily, for 14 days, with oxazepam or vehicle.125I-melatonin binding was recorded in synaptosomes prepared at 10.00, 18.00, and 24.00 h from the hypothalamus, hippocampus and medulla-pons of the rats. In the sham-operated, vehicle treated rats, specific125I-melatonin binding in all brain areas studied was higher at 18.00 h, whereas in the oxazepam-treated animals, binding was higher at 24.00 h than at the other times tested. In the pinealectomized, vehicle-treated rats, the binding recorded at 18.00 h in all three brain areas, was lower than at the other times of day tested. Oxazepam treatment decreased125I-melatonin binding at 24.00 h in the hippocampus and medulla-pons of the pinealectomized rats and did not significantly affect the binding in the hypothalamus. These results indicate the ability of oxazepam, pinealectomy and their combination, to manipulate the diurnal variations in125I-melatonin binding sites in the rat brain.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1438-2199
    Keywords: Amino acids ; Non-proteinogenic optically active amino acids ; D- and L-enantiomers ; Dehydroamino acids ; Chiral rhodium catalysts ; Asymmetric hydrogenation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Non-proteinogenic amino acids play an increasing role in oligopeptide chemistry. Their pharmacological and chemical properties, caused by D-configuration and “unnatural” residues, are more and more used for drug design. Different methods of asymmetric synthesis have been developed during the last decade to prepare “unusual” amino acids. One of them, the asymmetric hydrogenation of dehydroamino aids catalyzed by chiral rhodium (I) complexes, will be described. A series of examples, D- and L-configured, like naphthyl-, thienyl-, furyl-, and pyridylalanines, as well as phenylalanines substituted by chlorine, fluorine, p-nitro, p-methyl, p-trifluoromethyl, p-isopropyl, and p-tert-butyl have been prepared and characterized. Some analytical data like melting points and values of optical rotation are summarized in tables.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1440
    Keywords: Heart failure ; Idiopathic dilated cardiomyopathy ; Human myocardium ; Positive inotropic agents ; Force-frequency relationship ; Calcium homeostasis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In isolated papillary muscle strips from nonfailing donor hearts (NF) and from the hearts of patients with dilated cardiomyopathy with severe heart failure (NYHA IV), the force-frequency relationship was studied. Experiments were performed under basal conditions and in the presence of 0.01 μM or 0.1 μM isoprenaline and 0.02 μM ouabain. In NF, there was a positive inotropic effect following an increase of the stimulating frequency, whereas in NYHA IV, the force gradually declined under these conditions. Low concentrations (0.01) μM of isoprenaline prevented the negative inotropic effect in NYHA IV, whereas at 0.1 μM the mechanical function deteriorated in NF and NYHA IV. Ouabain had no effect on the force-frequency relationship compared to basal conditions. It is concluded that a reduction of high frequencies does improve the contractility in the failing myocardium. It is not unreasonable to speculate that this mechanism might be involved in the beneficial effects of drugs which reduce the heart rate, such as β-adrenoceptor antagonists and cardiac glycosides, in the condition of congestive heart failure in which the sympathetic tone is high.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Naturwissenschaften 77 (1990), S. 292-294 
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 179 (1996), S. 245-254 
    ISSN: 1432-1351
    Keywords: Bat ; Orientation ; Vision ; Echolocation ; Cumulative navigation error
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The orientation behaviour of bats (Phyllostomus discolor, Phyllostomidae), flying inside an octagonal “roost-like” chamber (ø: 100cm; h: 150cm) was examined. It has been shown that the bats begin turning manoeuvres during flight by turning their head towards the direction they intend to proceed to. During early phases of the flights, cumulative navigation errors were evident, indicating that endogenous spatial information plays a major role in the orientation of the bats. During later phases of the flight this error is diminished again. So it can be concluded that the bats start to use exogenous spatial information for orientation while approaching the target. In order to investigate the relative importance of vision, echolocation and endogenous spatial information for approaching the roost, the landing lattices inside the test arena were changed for non-grid dummies. We found that: 1. combined visual and endogenous information are more important than echoacoustical cues, 2. the bats learned quickly to switch their orientation behaviour in order to get a better performance in avoiding the dummies, 3. the learning performance was influenced by the visual similarity of dummies and the real landing lattice.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Der Unfallchirurg 101 (1998), S. 590-612 
    ISSN: 1433-044X
    Keywords: Key words Spinal injuries in children • Synchondrosis • Atlantooccipital dislocation • Odontoid fractures in children • Atlantoaxial dislocation • Pseudosubluxation • Discoligamentous instability • Operative treatment ; Schlüsselwörter Wirbelsäulenverletzungen bei Kindern • Entwicklung der Wirbelsäule • Diagnostik • Synchondrosen • Atlantookzipitale Dislokation • Densfrakturen bei Kindern • Atlantoaxiale Dislokation • Pseudosubluxation • Operative Behandlung • Diskoligamentäre Instabilitäten
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Verletzungen der Wirbelsäule sind bei Kindern extrem selten. Man kann davon ausgehen, daß sie etwa 0,2 % aller kindlichen Brüche und Verrenkungen und zwischen 1,5 und 3 % aller Wirbelsäulenläsionen ausmachen. Je jünger ein verletztes Kind, desto wahrscheinlicher liegt eine Läsion der oberen HWS vor. Dieser Abschnitt der Wirbelsäule ist im Vergleich zu Erwachsenen mit 50 % der HWS-Verletzungen überproportional häufig betroffen. Die meisten Unterschiede zwischen der Wirbelsäule des Erwachsenen und der des Kindes bestehen nur bis zum 10. Lebensjahr. Danach entsprechen Diagnostik, Klassifikation und Behandlung von Verletzungen weitgehend denen beim Erwachsenen. Bei Unkenntnis des normalen Aussehens und der normalen Entwicklung sind Fehlinterpretationen von Röntgenaufnahmen häufig. Typische Beispiele sind die Verwechslung von Synchondrosen mit Frakturen oder von Pseudosubluxationen des Atlas sowie des zweiten Halswirbels mit „echten“ Instabilitäten. Relevante Läsionen gehen immer auch mit eindeutigen klinischen Befunden einher. Besondere Verletzung der wachsenden Wirbelsäule sind Lösungen der Epiphysenplatten sowie „Frakturen“ der knorpeligen Zwischenzonen, der Synchondrosen. Atlantookzipitale Dislokationen (AOD) kommen besonders oft bei Kindern vor. Nach unseren Erfahrungen mit 16 AOD schlagen wir je nach Dislokationsrichtung der Okzipitalkondylen eine Einteilung in vordere, hintere und vollständig instabile AOD vor. Bei einem Jungen unseres Krankenguts konnte die Läsion durch eine temporäre interne Stabilisierung zur Ausheilung gebracht werden. Er zeigte eine weitgehende Erholung der anfangs hochgradigen neurologischen Ausfallserscheinungen. Verletzungen der Synchondrose des Dens axis stellen eine weitere typische Verletzung im Kindesalter dar. Vier von fünf Kindern aus dem eigenen Krankengut verunglückten bei Verkehrsunfällen. Drei saßen in Kindersitzen in Fahrtrichtung und waren mit einem 4-Punktgurt-System angeschnallt. Wir verwenden einen Halo-Ring mit Gipsweste für die konservative Behandlung. Operationsindikationen bestehen bei nicht retinierbaren sowie hochgradig instabilen Läsionen. Die operative Technik entspricht in allen Einzelheiten der beim Erwachsenen. 3 unserer 5 Kinder mit dieser Verletzung wurden erfolgreich operativ stabilisiert. Atlantoaxiale Dislokationen (AAD) werden in translatorische und rotatorische unterteilt. Sagittale Verschiebungen des Atlas bedürfen auch bei Kindern einer Fusion zwischen C1 und C2. Rotatorische Fehlstellungen lassen sich im frischen Stadium leicht reponieren und im Halo-Fixateur ausbehandeln. Auch bei veralteten Läsionen ist nach unseren Erfahrungen bei zwei Patienten teils durch offene, teils durch geschlossene Reposition eine Ausheilung in anatomischer Stellung möglich. Im Bereich der unteren HWS stellen neben Verletzungen mit Einengung des Spinalkanals vor allem solche mit ligamentärer oder diskoligamentärer Beteiligung– also Typ B- und C-Läsionen eine Operationsindikation dar. Sie heilen nämlich nach geschlossener Behandlung genauso wenig stabil aus wie bei Erwachsenen.
    Notes: Summary Injuries of the spine in children rarely occur. They amount to about 0.2 % of all fractures and dislocation and to 1.5 to 3 % of all lesions of the spine. The younger an injured child is, the more likely it has sustained a lesion of the upper cervical spine. This spinal segment in comparison to adults is concerned more often and accounts for 50 % of all C-spine injuries. Important differences between the adult spine and the spine in the child disappear with the age of 10 years. Later diagnostics, classification and treatment correspond widely with the principles valid in adults. The knowledge of the normal shape and development of the spine are crucial in avoiding misinterpretations of X-ray films. Typical examples include the confusion of synchondrosis with fractures or of subluxations of the atlas and the C2/C3 segment with “true” instabilities. Relevant lesions always are accompanied by clear clinical symptoms. Specific injuries of the growing axial skeleton are lesions of the cartilaginous endplates and “fractures” of the synchondrosis. Atlantooccipital dislocations (AOD) occur typically in children. According to our experiences with 16 AOD we propose – dependent on the direction of dislocation of the occipital condyles – a simplified classification in anterior, posterior and completely unstable AOD. In one boy in our series we treated the lesion successfully by temporary interal fixation. He presented a massive improvement of initially subtotal neurologic symptoms. Injuries to the synchondrosis of the dens represent another typical lesion in childhood. Four out of 5 children treated in our clinic were involved as back seat passengers in head-on motor vehicle accidents. Three of them were restrained by 4 point children's seat harnesses. For conservative treatment we prefer a halo and plaster-vest for 12 weeks after closed reduction. We recommend operative treatment in cases of major dislocation with greater instability where it may be impossible to maintain alignment with halo fxation. Surgical equipment and techniques correspond in detail to those used in adults. Three of the five children mentioned have been stabilized successfully by anterior screw fixation. Atlantoaxial dislocations (AAD) are devided into translatory and rotatory instabilities. Sagittal dislocations of the atlas in children also need to be fixed by a fusion between C1 and C2. Rotatory instabilities in the acute phase are easy to reduce and are treated with a halo-fixator. According to our experiences in two delayed cases anatomical reduction is also possible after months partly by open, partly by closed means. For the lower C-spine lesion with encroachment of the spinal canal and above all ligamentous injuries represent a clear indication for operative treatment because, similar to the adult spine, they do not become stable after close management.
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