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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 28 (1990), S. 379-383 
    ISSN: 1741-0444
    Schlagwort(e): Electromyography ; Muscular fatigue ; Upper limb
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 28 (1990), S. 374-378 
    ISSN: 1741-0444
    Schlagwort(e): Electromyography ; Muscular fatigue ; Power spectrum
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The shift in the power spectrum resulting from a 5–7 min fatigue-inducing effort followed by a 1–2 min recovery period of two elbow flexors, the biceps brachii (BB) and the brachio-radialis (BR), was assessed using two variables, the mean frequency Fm and the median or central frequency Fmd. These two variables were calculated in pre- and post-fatigue conditions and following a brief recovery, at four levels, namely 20, 40, 60 and 80 per cent of maximum voluntary contraction (MVC). These were taken from a ramped isometric effort that is from 0 to 100 per cent MVC. The EMG activity of the two flexors was recorded with bipolar surface electrodes from a group of ten volunteers. Following muscle fatigue, induced with a maintained 60 per cent MVC isometric contraction, a statistically significant (p〈0·05) shift towards the lower frequencies was observed for both Fm and Fmd for both muscles. Following a brief recovery, a shift towards the pre-fatigue higher frequencies was statistically significant (p〈0·05). These two synergists responded to muscle fatigue and recovery similarly, as they both demonstrated parallel shifts in power spectrum. The power spectrum is consequently a reliable measure of muscular fatigue. It is also complementary to the net articular moment results.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 30 (1992), S. 640-644 
    ISSN: 1741-0444
    Schlagwort(e): Elbow flexors and extensors ; Electromyography (EMG) ; EMG/force relationship ; Right/left sides ; Spectral analysis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Microscopy Research and Technique 28 (1994), S. 409-421 
    ISSN: 1059-910X
    Schlagwort(e): Extracellular matrix ; Image analysis ; 3D reconstruction ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: The epiphyseal growth plate and articular cartilage matrices were preserved by slam freezing and freeze substitution to optimally retain the native organization for both cellular and matrix components. These specimens were stained and examined using conventional electron microscopic methods. The highly integrated, proteoglycan-rich matrices were examined by computer image analysis using such parameters as distribution, connectivity, orientation, and a variety of morphometric analyses. Also, different aspects of electron tomography and 3D rendering of matrix vesicles and their associated mineral deposits from epiphyseal growth plates and turkey leg tendons are presented. © 1994 Wiley-Liss, Inc.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 5
    ISSN: 1615-6102
    Schlagwort(e): Cell wall synthesis ; Freeze substitution ; Fungal hyphae ; Golgi bodies ; Secretory vesicles ; Tip growth
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Secretory vesicles involved in cell wall synthesis (wall vesicles) and the Golgi apparatus have been compared in conventionally fixed and freeze substituted hyphae of the oomycete fungusSaprolegnia ferax. Wall vesicles freeze substituted in various fluids range from spherical to tubular and contain an intensely staining, phosphorous rich matrix. In contrast diverse conventional fixations cause artefactual constrictions in most tubular vesicles and loss of their intensely staining contents. These data are interpreted to show the existence of an intravesicular skeletal system, with cellular regulation, to determine vesicle morphology and intravesicular synthesis of a hypothetical phosphorylated glycolipid cell wall precursor. Whilst freeze substitution gives superior preservation of wall vesicle morphology, it does not demonstrate any preferential association between wall vesicles and microtubules thus suggesting that microtubules are only indirectly involved in wall vesicle transport. Freeze substitution is superior to conventional fixation for analysis of the Golgi apparatus because it uniquely reveals both differentiation of a specific single cisterna in each Golgi body and greater differences in membrane thicknesses throughout the endomembrane system.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 24 (1986), S. 337-343 
    ISSN: 1741-0444
    Schlagwort(e): Electromyography ; Gait
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract The aim of the present study was to validate the notion that there is a normal profile for electromyographic (EMG) signals in gait. For eight subjects, surface electrodes were used to record signals over ten strides from the soleus, rectus femoris, biceps femoris, vastus medialis and tibialis anterior muscles. Analyses of EMG linear envelopes, normalised with respect to both time and amplitude, demonstrated that statistically significant differences exist in amplitude of activity across subjects for all muscles, and that within subjects the data were highly repeatable. More importantly, differences in profiles of activity were found especially for the rectus femoris muscle. It was also found that a given muscle from a given subject can present specific profiles, but usually these specificities are averaged out in the pooled between-subject data. Thus limits exist with the use or the notion of a normal profile of EMG for gait.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 9-15 
    ISSN: 0741-0581
    Schlagwort(e): Calcifying cartilage ; Mineral crystals ; Matrix vesicles ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Biological mineralization is a cell-mediated process which is believed to be triggered by a “nucleating agent.” Various matrix structures, such as matrix vesicles, collagen fibrils and macromolecules, have been claimed to be the source of this substance, since these components have been found by transmission electron microscopy (TEM) of thin sections to be associated with early mineral crystals. Systematic image analysis of the relationships revealed in electron micrographs between specific matrix components and early mineral deposits has shown that unequivocal image interpretation is not possible. This is due principally to the problems posed by overprojection and truncation phenomena, since the structures being analyzed lie within the same dimensional range as thin section thickness. Various examples are illustrated and discussed. The site at which mineral crystals are initially laid down thus cannot be identified with any matrix structure using thin section TEM. Possible technical approaches to resolve this problem of image analysis are discussed.
    Zusätzliches Material: 13 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 18 (1991), S. 262-268 
    ISSN: 0741-0581
    Schlagwort(e): Collagen ; Mineral ; Calcification ; Tendon ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Allgemeine Naturwissenschaft
    Notizen: Turkey leg tendons at an early stage of mineralization have been thin sectioned and imaged by electron microscopy. At this stage collagen-associated mineral apatite was found to be present within both the gap and overlap zones. The earliest apatite occurs in a microcrystalline form which gives a rather generalized and characteristic density to both the gap and overlap zones; with subsequent development larger defined apatite crystals arise which span gap/overlap zones. Fourier transformation of such images revealed the major 67 nm axial repeat of the gap/overlap zone plus four other maxima corresponding to repeat spacings of 22, 16, 13, and 11 nm respectively. Computer imaging techniques were used to reconstruct images by using selected spatial frequencies from such transforms. In this manner the subperiodic distributions of mineral were visually enhanced. These subperiodicities are positioned in an asymmetric fashion over the entire D unit repeat aligning with the molecular orientation of the fibril. Analyses of both negatively stained collagen and computer-generated maps of collagen hydrophobicity were compared to the mineral distribution of collagen. Densitometric comparisons showed a positional correlation between the axial banding patterns of mineralized fibrils and those of negatively stained non-mineralized fibrils. Comparable spatial frequencies were also present in transforms between hydrophobic maps and mineral distribution of collagen. These results suggest that the lateral clusterings of hydrophobic residues which span the fibril at specific sites in both the gap and overlap zones serve to prohibit early mineral deposition. This observed hydrophobic influence in combination with the gap space appear as contributing factors in the observed axial distribution of mineral within collagen.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
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  • 9
    Publikationsdatum: 1983-03-01
    Print ISSN: 0027-8424
    Digitale ISSN: 1091-6490
    Thema: Biologie , Medizin , Allgemeine Naturwissenschaft
    Standort Signatur Erwartet Verfügbarkeit
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  • 10
    Publikationsdatum: 2016-10-12
    Print ISSN: 2469-9950
    Digitale ISSN: 2469-9969
    Thema: Physik
    Publiziert von American Physical Society
    Standort Signatur Erwartet Verfügbarkeit
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