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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 456 (1985), S. 0 
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Applied crystallography online 14 (1981), S. 191-202 
    ISSN: 1600-5767
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The present study presents the first small-angle neutron scattering experiment of lipid bilayers in excess water. The method of solvent contrast variation was applied. The variation of scattering intensity with the scattering angle could be analysed in terms of the Kratky–Porod model of scattering by quasi-two-dimensional systems. From this the bilayer thickness of unilamellar vesicles of dimyristoyllecithin was determined to be d = 41 ± 1 Å at 310 K. Several typical mixtures of different lecithins with varying chain lengths and of lecithin with phosphatidic acid were studied. By deuteration of one lipid component a very large contrast between segregated phases could be achieved. It was thus possible to distinguish clearly between homogeneous mixtures and mixtures which exhibit a heterogeneous lipid organization. In the latter case no intensity matching upon solvent contrast variation was possible. It is shown that phase boundaries may be determined very accurately by performing contrast variation experiments with at most two mixtures of different initial composition. The main advantage of the present method is that lateral phase separation may also be clearly studied in fluid states of the bilayer. From the average scattering-length densities one can determine the density of the lipid layers and thus the excess volumes of the mixtures. For lecithin mixtures positive excess volumes are observed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of dermatological research 277 (1985), S. 484-488 
    ISSN: 1432-069X
    Keywords: Mechanical properties ; Repeated strain in vivo ; Time dependence of recovery
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A new method was developed to study the in vivo recovery of mechanical properties of rat skin after repeated strain. Full recovery, i.e., restitutio ad integrum, can be observed only in in vivo experiments but not in in vitro conditions. For the in vivo studies, tabs were fastened on the back skin of rats to test stress-strain behaviour both perpendicular and longitudinal to the body axis. Under anesthesia, skin was extended repeatedly 30 times to an elongation of up to 50% of the distance between the tabs. The experiment was repeated in the same animals at either 0.5, 1, 6, or 16 h. Differences depending on the direction of stretching versus body axis were observed during the first run. A decrease in stress values depending on the logarithm of the number of cycles was found, in both directions, to be attributable to the relaxation phenomenon. The measured stress values after 0.5, 1, and 6 h were considerably lower compared to the first run, thus indicating an incomplete recovery. After 16 h, an almost complete recovery was observed, so that, in perpendicular samples, even higher values were observed, thus indicating an overshooting of the repair mechanisms. The difficulties associated with obtaining appropriate physical and mathematical models for the mechanical properties of skin are discussed.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Acta neuropathologica 77 (1988), S. 219-223 
    ISSN: 1432-0533
    Keywords: Meningioma ; Folliculo-stellate cell ; Pituitary neoplasm ; Electron microscopy ; Immunochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A tumor arising in the pituitary fossa and having some of the histological and ultrastructural features of a recently described tumor, purportedly originating from the folliculo-stellate cells of the anterior pituitary, is presented. The results of our ultrastructural and immunohistochemical studies, however, favored a meningeal origin and suggested that the neoplasm was most likely a secretory meningioma.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Development genes and evolution 191 (1982), S. 202-204 
    ISSN: 1432-041X
    Keywords: Sperm binding ; Sea urchin eggs ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of trypsin on the fertilizability of sea urchin eggs was studied withParacentrotus lividus andPseudocentrotus depressus. The main effects were two reductions of fertilizability, with a transient increase intervening. The first decrease was probably caused by degradation of sperm-binding sites at the vitelline sheet and the second by degradation of binding sites on the plasma membrane.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 7 (1981), S. 329-329 
    ISSN: 1432-1017
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1076
    Keywords: Desquamative interstitial pneumonitis ; Alveolar lipoproteinosis ; Cytomegalovirus disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A desquamative, interstitial pneumonitis was diagnosed histologically in a 9-month-old boy who first became ill at the age of 5 weeks. The desquamative interstitial pneumonitis was associated with an acquired cytomegalovirus (CMV) infection. Despite treatment with corticoids, acyclovir and artificial ventilation, the patient died of pulmonary insufficiency at the age of 15 months. The autopsy revealed an alveolar lipoproteinosis.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 64 (1986), S. 264-271 
    ISSN: 1432-1106
    Keywords: Sensory threshold ; Microgravity ; Linear acceleration ; Adaptation ; Otoliths
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Thresholds for the detection of linear oscillatory motion at 0.3 Hz in the X, Y and Z body axes were determined during the flight of Spacelab-1 and on the ground pre- and post-flight, using the method of limits with a single staircase procedure. Pre-flight, Z axis thresholds (mean 0.077 ms−2) were significantly higher than X and Y thresholds (mean 0.029 ms−2). Measures obtained on three crew members in-flight exhibited thresholds greater, by a factor of 1.5–4.3, than those obtained pre-flight. Post-flight, two crew members had significantly elevated X and Y axis thresholds whereas the other two crew members had lowered thresholds in X, Y and Z axes. In general, thresholds had returned to pre-flight levels by the second post-flight day. A possible explanation for these somewhat disparate responses is presented.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1106
    Keywords: Vestibular instrumentation ; Methodology ; Spacelab-1 mission ; Hardware ; Microgravity research
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A series of vestibular experiments were performed in conjunction with the first Spacelab mission, consisting of sets of pre-, in- and postflight tests. A multipurpose experimental apparatus used for the diverse flight and ground tests is presented. Additional apparatus together with the multi-purpose package were used in the baseline data collection facility at the landing site at NASA Dryden Flight Research Facility for the ground tests. The tests involved optokinetic, caloric and mechanical (whole-body or head-alone) stimulation. The latter included linear acceleration in the subject's x, y and z axes, static roll and yaw about an earth-vertical axis. Physiological parameters such as electro-oculogram (EOG), blood-volume-pulse (BVP), respiration, as well as the stimulus variables such as acceleration and caloric temperature were transmitted to the ground and recorded there. The flight and ground testing schedules are outlined. Problems arising from this complex venture are discussed, and some suggestions are made for future improvement.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Experimental brain research 64 (1986), S. 284-290 
    ISSN: 1432-1106
    Keywords: Ocular counterrolling ; Space adaptation ; Vestibular asymmetry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The static ocular counterrolling (OCR) of the four scientific crew members in the first Spacelab mission was measured during baseline-data-collection before and after the flight of SL-1. It was presumed that the modification of otolithic responses during spaceflight will be reflected in specific changes of the OCR-gain on the first days after recovery. The magnitude of OCR was determined analysing colour-transparencies of subjects right eyes that were produced in different positions of lateral body tilt. In general, one subject did not show any changes at all; three subjects exhibited a significant decrease of OCR-gain after exposure to weightlessness, whereby differences could be found between the responses for small and large angles of lateral body tilt. Moreover, asymmetrical effects of OCR-gain were found between body tilt to the left and tilt to the right side. Two subjects already demonstrated such an asymmetry before the flight with the higher gain on left-tilt (or right eye up), and three subjects exhibited left-right asymmetries after the spaceflight with the higher gain tilting to the right (or right eye down). A possible correlation between these vestibular asymmetries and space-sickness susceptibility is discussed.
    Type of Medium: Electronic Resource
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