ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Activated fibres' territory  (2)
  • Analytical Chemistry and Spectroscopy  (2)
  • 1995-1999  (1)
  • 1990-1994  (3)
  • 1
    Electronic Resource
    Electronic Resource
    Radial changes of extracellular potential amplitude and integral characteristics and the inverse problem in electroneurography (1992)
    Springer
    Medical & biological engineering & computing 30 (1992), S. 357-363 
    Details
    ISSN: 1741-0444
    Keywords: Activated fibres' territory ; Desynchronisation ; Extracellular potential amplitude ; Extracellular potential integral ; Fibre-electrode distance ; Fibre excitation parameters ; Inverse problem
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The possibility of solving the inverse problem in electroneurography, i.e. of estimating the main parameters specifying the activated fibre's functional state, using the amplitude and integral characteristics of the surface potentials generated by infinite homogeneous fibres, has been analysed. An analytical expression has been found for the amplitude of the negative phase Anph of the single fibre extracellular action potential (SFEAP) as a function of the wavelength b, the fibre-electrode distance y and a scale factor Ao proportional to the intracellular action potential amplitude Vm, to the square of the fibre radius a and to the ratio of the axoplasm conductivity τa and volume conductor conductivity τe. For a large fibre-electrode distance, typical of surface recordings, an analytical expression of the integral of the negative phase Inph of the SFEAP as a function of Ao, b, y and the propagation velocity v was also found. Simple methods are proposed for estimating v, the location of the electrical centre of the activated fibres' territory and the product of the number of activated fibres N, duration Tin of the intracellular action, potential and of the factor Ao. The estimation errors due to the temporal and spatial dispersion of the activated fibres were analysed as a function of the fibre-electrode distance and the territory shape.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446975
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Use of surface potential spectral characteristics for solving the inverse problem in electroneurography (1992)
    Springer
    Medical & biological engineering & computing 30 (1992), S. 399-405 
    Details
    ISSN: 1741-0444
    Keywords: Activated fibres' territory ; Anisotropy ratio ; Desynchronisation ; Frequency-dependent volume conductor ; Inverse problem ; Power spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract The changes in the power spectra of single-fibre extracellular action potentials (SFEAPs) generated in an infinite anisotropic frequency-dependent volume conductor, which occurred as a result of alterations in the propagation velocity v and duration Tin of the intracellular action potential (IAP) were analytically determined. Effects of the temporal and spatial dispersions of almost synchronously activated fibres on the power spectrum of compound extracellular potentials (CEPs) were analysed for different shapes and sizes of the activated fibres' territory. It was found that, as a result of desynchronisation in the fibres' activation, dips existed in the CEP power spectra and that the frequencies of the dips depended on the degree of desynchronisation but did not depend on the velocity. It was shown that the hypothetical power spectrum of compound IAP was sensitive to the variations in the desynchronisation in the fibres' activation and in the risetime and duration of IAP even at a great fibre electrode distance typical for surface recordings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02446167
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Restricted rotation of the phenyl group in β-hydroxyphosphonates: Dynamic NMR and semiempirical studies (1994)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 32 (1994), S. 639-645 
    Details
    ISSN: 0749-1581
    Keywords: NMR ; 1H NMR ; 13CNMR ; Dynamic NMR ; β-Hydroxyphosphonates ; Restricted rotation ; Steric effects ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Free energies of activation, ΔG298≠, for the rotation of the phenyl group in the range of 46.06-63.25 kJ mol-1 were observed in some model β-hydroxyphosphonates. These barriers were found to depend on the type of substituents at the phosphorus atom and on the substituents at the β-position with respect to the phenyl ring. The steric origin of this observation is discussed. Dynamic NMR studies were performed in order to determine the activation parameters for the exchange process. For that purpose, variable-temperature 1H and 13C NMR spectra were treated by non-iterative, iterative and iterative double-fit procedures. MNDO, AM1 and PM3 theoretical calculations of the barriers for three of the compounds studied are reported and results are compared with the experiments. It is found that the PM3 results are very close to the experimental data.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260321102
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Dynamic NMR: A new procedure for the estimation of mixing times in the 2D EXSY experiments. A four-site exchange system studied by 1D and 2D EXSY spectroscopy (1995)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 33 (1995), S. 739-744 
    Details
    ISSN: 0749-1581
    Keywords: 1H NMR ; 2D EXSY NMR ; mixing time ; complete lineshape analysis ; double-fit method ; barriers to restricted rotation ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure for the estimation of the mixing time between the last two 90° pulses in the classic three-pulse sequence NOESY/EXSY is proposed and tested and some considerations for the treatment of the two-dimensional (2D) 1H NMR exchange spectra are given. The rate constants are thus obtained with reasonable precision. This procedure was followed to obtain the 2D spectra of the model compound α-[bis(dimethylamino)methylene]-4-nitrophenylacetonitrile, which represents a four-site exchange system. The barriers to restricted rotations found in this compound were also determined from one-dimensional (1D) 1H NMR spectra, which were processed with the iterative complete lineshape analysis (CLSA) method. The double-fit approach was incorporated in the CLSA method. It is shown that the results from the 2D dynamic NMR spectral studies corroborate those obtained by the CLSA double-fit method.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260330909
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...