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  • 1
    Electronic Resource
    Electronic Resource
    Photopigment conversions expressed in receptor potential and membrane resistance of blowfly visual sense cells (1975)
    [s.l.] : Nature Publishing Group
    Nature 254 (1975), S. 520-522 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Recent evidence is provided by the work of Hochstein et al.1 on the barnacle and Minke et al.2 on Limulus who demonstrated that light-evoked changes in resistance and potential of the receptor cell membrane depend on the photopigment conditioning. Their experiments are founded on two crucial facts ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/254520a0
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  • 2
    Electronic Resource
    Electronic Resource
    Photopigment conversions expressed in pupil mechanism of blowfly visual sense cells (1975)
    [s.l.] : Nature Publishing Group
    Nature 253 (1975), S. 740-742 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We have already investigated7 the pupil mechanism of the blowfly Calliphora erythrocephala by measuring the transmission of the photoreceptors and found that the absorbance of the pigment granules is extreme in the blue and minimal in the yellow. We concluded that, for the photochemical cycle of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/253740a0
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  • 3
    Electronic Resource
    Electronic Resource
    High-precision Repetitive Firing in the Insect Optic Lobe and a Hypothesis for its Function in Object Location (1965)
    [s.l.] : Nature Publishing Group
    Nature 206 (1965), S. 1158-1160 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1. Waveform of a spike Fig. 2. Spike repetition rate in relation to the body-temperature, measured with a thermocouple in the thorax Specific mention is made of this and of the following general characteristics of the phenomenon, since the fact that our power-line frequency is 50 c/s is ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/2061158b0
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  • 4
    Electronic Resource
    Electronic Resource
    Non-linear Microphonic Response of Labyrinth Organs to Stimuli consisting of Two Pure Tones (1955)
    [s.l.] : Nature Publishing Group
    Nature 175 (1955), S. 383-384 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The most interesting aspects of these curves are : (1) The frequency of the response (A and B) is twice the frequency of the stimulus. (2) In the combined effect (7), the response to the high frequency is large at the negative peaks and small at the positive peaks ; the latter correspond ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/175383b0
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  • 5
    Electronic Resource
    Electronic Resource
    Accuracy and the influence of marrow fat on quantitative CT and dual-energy X-ray absorptiometry measurements of the femoral neck in vitro (1996)
    Springer
    Osteoporosis international 6 (1996), S. 25-30 
    Details
    ISSN: 1433-2965
    Keywords: Absorptiometry ; Accuracy ; Bone ; Comparative study ; Dual-energy X-ray ; Femur ; In vitro ; Marrow fat, Quantitative CT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Bone mineral measurements with quantitative computed tomography (QCT) and dual-energy X-ray absorptiometry (DXA) were compared with chemical analysis (ChA) to determine (1) the accuracy and (2) the influence of bone marrow fat. Total bone mass of 19 human femoral necks in vitro was determined with QCT and DXA before and after defatting. ChA consisted of defatting and decalcification of the femoral neck samples for determination of bone mineral mass (BmM) and amount of fat. The mean BmM was 4.49 g. Mean fat percentage was 37.2% (23.3%–48.5%). QCT, DXA and ChA before and after defatting were all highly correlated (r〉0.96,p〈0.0001). Before defatting the QCT values were on average 0.35 g less than BmM and the DXA values were on average 0.65 g less than BmM. After defatting, all bone mass values increased; QCT values were on average 0.30 g more than BmM and DXA values were 0.29 g less than BmM. It is concluded that bone mineral measurements of the femoral neck with QCT and DXA are highly correlated with the chemically determined bone mineral mass and that both techniques are influenced by the femoral fat content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01626534
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  • 6
    Electronic Resource
    Electronic Resource
    Skin thickness does not reflect bone mineral density in postmenopausal women (1994)
    Springer
    Osteoporosis international 4 (1994), S. 32-35 
    Details
    ISSN: 1433-2965
    Keywords: Cross-sectional study ; Bone mineral density ; Osteoporosis ; Postmenopause ; Skin thickness ; Ultrasound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Skin and bone both contain primarily type I collagen in connective tissue matrices and are assumed to be related due to this common organic constituent. The purpose of this study was to investigate whether skin thickness measurements by ultrasound (US) could be used for screening for low bone mass. In 94 healthy, white, non-smoking women, 1–3 years postmenopause, the thickness of the skin of the left upper arm and forearm was measured by ultrasound (US). These measurements were compared with values of bone mineral density (BMD) as measured by quantitative computed tomography (QCT) of the lumbar spine and quantitative video micro-densitometry (QMD) of the hand. The correlation found between US skin thickness measurements and BMD results was of low magnitude and not significant. It is concluded that US measurements of skin thickness cannot be used to screen early postmenopausal women for low bone mass.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02352258
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  • 7
    Electronic Resource
    Electronic Resource
    Vertebral Dimensions: Influence of X-Ray Technique and Patient Size on Measurements (1998)
    Springer
    Calcified tissue international 62 (1998), S. 214-218 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Vertebral dimension — Correction — Osteoporosis — Technique — Patient size
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. In this study a new reference value, ``corrected vertebral dimension,'' is presented for vertebral height measurements. Of 68 females (age 18–88 years; mean 44.2 years) and 40 males (age 16–81 years; mean 55 years) the projected vertebral dimensions (T4–L5) were measured on lateral radiographs. In addition to this, the vertebra-to-film distances (VFD) were measured and a fixed focus-to-film distance (FFD) was used during the study. Corrected dimensions of the thoracic and lumbar vertebrae (T4–L5) were calculated using the FFD and VFD. These corrected dimensions were then used to recalculate projected vertebral dimensions at different focus-to-film distances. The applied geometric corrections were verified in a phantom study representing an in vitro situation. The results indicate that studies using different X-ray techniques for making lateral radiographs of the spine can become comparable when using corrected vertebral dimensions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900420
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  • 8
    Electronic Resource
    Electronic Resource
    On the correlation model: Performance of a movement detecting neural element in the fly visual system (1978)
    Springer
    Biological cybernetics 31 (1978), S. 163-168 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The applicability of the basic principles of the correlation model to the description of the activity of a movement detecting neuron in the third optic ganglion of the fly's visual system has been investigated. This wide field neuron is supposed to sum the outputs of a large number of correlators (i.e. multiplying units followed by time averagers) that are distributed over almost the entire eye. The model describes and predicts the experimental results in a satisfactory way if a uniformly distributed system of correlators is assumed. The sampling base of the correlators in this system equals the interommatidial angle Δϕ. The half width of the spatial sensitivity distribution of the visual inputs of the correlators, Δϱ, is equal to the half width of the retinula cells of the 1–6 system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00337002
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  • 9
    Electronic Resource
    Electronic Resource
    The effect of air velocity on the wingstroke frequency of the blowflyCalliphora erythrocephala (1983)
    Springer
    Journal of comparative physiology 153 (1983), S. 289-297 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of air velocity and pressure on the wingstroke frequency ofCalliphora erythrocephala, flying in a windtunnel, was studied. The results can be understood by considering the flight mechanism as a mechanical oscillator with an inertia, that depends on air velocity and pressure, without any need for nervous control. The effect of changes in air velocity on the wingstroke frequency was calculated, taking the inertia of a steady two-dimensional boundary layer around the wings as the variable part of the inertia of the flight mechanism. The calculated effect was ten times smaller than that observed experimentally. The reason for this discrepancy is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00612583
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  • 10
    Electronic Resource
    Electronic Resource
    Organization of visual axes in the compound eye of the flyMusca domestica L. and behavioural consequences (1975)
    Springer
    Journal of comparative physiology 102 (1975), S. 305-320 
    Details
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The previously derived optical demands for the neural superposition eye are experimentally tested in the compound eye ofMusca domestica L. The optical requirements are fulfilled except in the marginal regions. Taking into account the gradient in spatial packing density of ommatidial axes in a horizontal direction the expected torque response of the fly is calculated and compared with results obtained by Reichardt (1973). The similarity of the curves suggests that existing gradients in the part of the neural network serving this orientation behaviour may be negligible with respect to the studied geometrical gradient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01464343
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