PubMed · 1808241
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
N Yoshiyama, F Marumo. 1991. [Dialysis].. https://pubmed.ncbi.nlm.nih.gov/1808241/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
The use of two-dimensional diffusion-edited total-correlation NMR spectroscopy (DETOCSY) to measure diffusion coefficients of molecules in biofluids is demonstrated. The method takes advantage of the increased peak dispersion in a two-dimensional spectrum and allows the measurement of diffusion coefficients of individual molecules in complex biofluid samples in a condition close to their natural state. The NMR spectra can be edited on the basis of diffusion coefficient, and hence, approximate molecular size and this provides a qualitative means of simplifying the spectra for assignment purposes. The use of two-dimensional DETOCSY NMR spectra increases the probability that the individual cross-peaks arise from single components and hence allows single-exponential fitting of the magnetic field gradient dependence of cross-peak volumes. Interpretation of the derived diffusion coefficients improves the NMR resonance assignment process in complex biofluid mixtures by giving additional information on the molecular size. The DETOCSY approach also provides information on small molecule-macromolecule interactions such as the binding of drugs or endogenous species to serum proteins such as albumin.
With reference to the Ornstein-Uhlenbeck model for single neuron activity, computational results and theoretical arguments are provided to discuss the accuracy and the appropriateness of analytical approximations to first-passage-time densities and its moments. A gamma approximation is initially discussed, use of which is successively made to construct a probability density of a new form that appears to be particularly suitable to approximate the as yet unknown firing probability density function.
Aiming at an improvement of the existing neuronal models, we consider a mixed process ensuing from the superposition of continuous diffusions and of Poisson time-distributed sequence of impulses and focus our attention on the moments of the firing time. In particular, we consider three different instances: the large jumps model in which each jump causes the neuron firing, the reset model characterized by jumps towards the resting potential and a more general model where constant amplitude excitatory and inhibitory jumps are superimposed on diffusion. By resorting to analytical arguments and to numerical computations, the main behavioral differences of the considered models are outlined.