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  • General Chemistry  (15)
  • Biochemistry and Biotechnology  (3)
  • Myoelectric  (3)
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 29 (1991), S. 84-88 
    ISSN: 1741-0444
    Schlagwort(e): Control ; Interference ; Myoelectric ; Performance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract Myoelectric signal is an important source of control information for powered prostheses. A commonly used performance measure for the signal processors of such control systems is the ratio of processor output mean to variance. This ratio (SNR) is a function of a number of factors including physiological parameters and additive interference. The paper investigates the effects of motor unit physiological parameters and interference on control performance, with particular reference to SNR. Performance equations are derived and verified within vivo experiments. The results show a complex interaction among the physiological parameters and interference. A particular point of interest is the misleading SNR values that can occur under certain recruitment and interference conditions.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 0887-3585
    Schlagwort(e): interleukin-4 ; circular dichroism spectroscopy ; site-directed mutagenesis ; protein structure modeling ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Medizin
    Notizen: The structure of human interleukin 4 (IL-4) was predicted utilizing a series of experimental and theoretical techniques. Circular Dichroism (CD) spectroscopy indicated that IL-4 belonged to the all α-helix class of protein structures. Secondary structure prediction, site-directed mutagenesis, and CD spectroscopy suggested a predominantly α-helical structure, consistent with a four-helix bundle structural motif. A human/mouse IL-4 chimera was constructed to qualitatively evaluate alternative secondary structure predictions. The four predicted helices were assembled into tertiary structures using established algorithms. The mapping of three disulfide bridges in IL-4 provided additional constraints on possible tertiary structures. Using accessible surface contact area as a criterion, the most suitable structures were right handed all antiparallel four-helix bundles with two overhand loop connections. Successful loop closure and incorporation of the three disulfide constraints were possible while maintaining the expected shape, solvent accessibility, and steric interactions between loops and helices. Lastly, energy minimization was used to regularize the chain.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 20 (1982), S. 251-252 
    ISSN: 1741-0444
    Schlagwort(e): Batteries ; Myoelectric ; Prothesis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Medical & biological engineering & computing 28 (1990), S. 225-231 
    ISSN: 1741-0444
    Schlagwort(e): Motor unit firing ; Motor unit recruitment ; Myoelectric ; Signal-to-noise ratio
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: Abstract An important measure of the performance of a myoelectric control channel for powered artificial limbs is the myoelectric signal processor output signal-to-noise ratio (SNR). The signal and noise in this context are, respectively, the mean and variance of the estimate of some signal parameter to be used for control purposes. These quantities are determined by the signal processor, motor unit recruitment and motor unit firing statistics. The paper investigates, through analytical, simulation and experimental work, the role and significance of recruitment and firing statistics in channel performance. Equations are derived which express, for the single and multi-unit cases, channel SNR as a function of the number of active units, firing rates, action potential amplitude variation and action potential moments. A computer-simulated myoelectric signal is generated in which these variables can be controlled and SNR measured. The simulation results are compared with the theoretical and found to agree very well. Limited experiments with wire intramuscular electrodes and surface electrodes are performed to measurein vivo SNR from the biceps brachii muscle. The results of the experiments agree well with those of the simulation and theoretical work. The significance of this work is that it provides insight into the roles of important physiological parameters in myoelectric channel performance. It will also provide data necessary for the development of SNR enhancement techniques.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    New York : Wiley-Blackwell
    Journal of Bioluminescence and Chemiluminescence 4 (1989), S. 507-511 
    ISSN: 0884-3996
    Schlagwort(e): Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Advent of the multichannel plate and position sensitive detector has made possible true single photon counting imaging tubes. We have investigated the application of these detectors in studies of the ultraweak light emission of biological materials. Initially, we focussed our efforts on two objectives: (1) obtaining single photon counting images of living tissues using only the light (chemiluminescence) emitted by the specimen and (2) developing means of obtaining well-resolved spectra of weakly emitting sources. We have obtained a variety of images. One striking result of this work is the first observation of tissue specific localization of photon emission in situ. Using this detector we have also obtained the first well-resolved spectra of some important ultraweak emission processes. These results illustrate the potential use of single photon imaging in bioluminescence and chemiluminescence research.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Chemistry - A European Journal 3 (1997), S. 765-771 
    ISSN: 0947-6539
    Schlagwort(e): aromatic stacking ; crystal engineering ; diamondoid networks ; packing model ; supramolecular chemistry ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: The ability to predict and subsequently control solid-state structure has been identified as a major challenge in the field of crystal engineering. Here we suggest the concept of constitutive models as a tool for understanding crystal packings and for designing new solid-state structures. Such models are intended to relate molecular interactions and their geometrical constraints with solid-state organization. These models will most likely be of greatest use for crystals consisting of supramolecular networks, that is, infinite assemblies of small molecules associating through strong, directional, and selective noncovalent interactions. The concept of the constitutive packing model is illustrated for interpenetrated diamondoid coordination networks based on crystalline adducts of 4,4′-biphenyldicarbonitrile with silver(I) salts. Observed structural deformations induced by counterions of varying size may be understood in terms of the interference of two supramolecular networks within this system: the diamondoid metal-ligand coordination network and face-to-face aromatic stacks of the organic ligand. The constitutive model developed here has been applied to other diamondoid coordination networks in the literature and is found to be general.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 0044-8249
    Schlagwort(e): Carbanionen ; Lithiumverbindungen ; NMR-Spektroskopie ; Phosphorverbindungen ; Strukturaufklärung ; Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Weinheim : Wiley-Blackwell
    Electrophoresis 19 (1998), S. 3190-3198 
    ISSN: 0173-0835
    Schlagwort(e): Wheat ; Proteins ; Buffers ; Gliadins ; Capillary electrophoresis ; Chemistry ; Biochemistry and Biotechnology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie
    Notizen: Studies were conducted to produce faster, simpler, more rugged protocols for separating wheat proteins by high performance capillary electrophoresis (HPCE). Three areas were targeted for improvement: initial capillary equilibration procedures, buffer composition, and post-separation rinsing procedures. For the initial equilibration of capillaries, a brief rinse with a hydroxypropylmethylcellulose (HPMC) solution was the most critical factor for successful separation of wheat proteins. To reduce separation time and maintain resolution, β-alanine and glycine were each used in place of sodium phosphate as buffer ions. Two isoelectric buffers, aspartic acid and iminodiacetic acid (IDA) were also tested. Each of these four buffer systems generated substantially lower currents, and provided faster separations, than sodium phosphate-based buffers. Finally, post-separation rinsing procedures were re-examined with the goal of reducing the time necessary to rinse the capillary after each separation. A critical factor in achieving this goal was removal of albumins and globulins prior to separation. These proteins bind to the capillary wall and cause rising baselines and excessive peak tailing. Once these proteins were removed, capillaries could be rinsed with buffer for only 2 min between separations. Capillary equilibration procedures were shortened from 90 min to 30 min. Likewise, separation times were reduced by ∼ 40% (25 min to 15 min) by using glycine in place of sodium phosphate in the separation buffer. Finally, post-separation times were reduced by 80% (10 min to 2 min). Overall, these factors resulted in a reduction in total separation time of 50% (35 to 17 min) and maintained high resolution separations and good run-to-run repeatability.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 9
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 10
    ISSN: 0044-8249
    Schlagwort(e): Chemistry ; General Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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