Biomedical subjects

K V Klementev

Publications and source records attributed to K V Klementev.

3 recordsLinked to original sources

PubMed2001

The use of prior information for extracting the post-edge background.

A new method for extracting the post-edge background mu0 is proposed, the method of Bayesian smoothing. A further evolution of the smoothing spline method is considered as well. Both techniques are capable to take into account prior information about the peculiarities on the mu0. In addition, since the Bayesian approach works in terms of the posterior probability density functions, it contains a natural way to determine the errors of the mu0 construction, which has always been an unresolvable problem for any other method. Even with use of the prior information, which narrows the posterior probabilities, the errors of mu0 are shown to be larger than the experimental noise.

Journal Article↗

PubMed2001

Statistical evaluations in fitting problems.

The problem of error analysis is considered taking into account all possible correlations and a prior information about the accessible parameter space. Special attention is paid to the correct determination of the relative weight of experimental data and the a priori guess. The applications of statistical chi2- and F-tests to the fitting problems are also discussed.

Journal Article↗

PubMed2001

Lattice softening in superconducting compositions of Ba(K)BiO3.

Temperature dependent x-ray absorption spectra investigation were measured for Ba(1-x)K(x)BiO3 (Bi L3-edge) with x =0.0, 0.25, 0.4, 0.5 and for BaPbO3 (Pb L3-edge). It was found that at low temperatures the Debye-Waller factor of the square diagonal Bi-Bi bond has the maximum value near the insulator-metal phase transition for the compound with x = 0.25 and x = 0.4. Temperature dependence of the Debye-Waller factor of Bi-Bi bond strongly differs from the Einstein model curve that well describes the harmonic systems (for example BaPbO3). This behavior is consistent with the strong anharmonicity of the Bi-O shell due to the double-well vibration potential reported by us earlier. Presented results point to the essential lattice softening of the superconducting compositions, which is important for the understanding of superconductivity mechanism in perovskite type oxides.

Journal Article↗