2 resultados para Random matrix theory
em Brock University, Canada
Resumo:
A review of the literature reveals that there are a number of children in the educational system who are characterized by Attention Deficit Disorder. Further review of the literature reveals that there are information processing programs which have had some success in increasing the learning of these children. Currently, an information processing program which is based on schema theory is being implemented in Lincoln County. Since schema theory based programs build structural, conditional, factual, and procedural schemata which assist the learner in attending to salient factors, learning should be increased. Thirty-four children were selected from a random sampling of Grade Seven classes in Lincoln County. Seventeen of these children were identified by the researcher and classroom teacher as being characterized by Attention Deficit Disorder. From the remaining population, 17 children who were not characterized by Attention Deficit Disorder were randomly selected. The data collected were compared using independent t-tests, paired t-tests, and correlation analysis. Significant differences were found in all cases. The Non-Attention Deficit Disorder children scored significantly higher on all the tests but the Attention Defici t Disorder children had a significantly higher ratio of gain between the pretests and posttests.
Resumo:
Second-rank tensor interactions, such as quadrupolar interactions between the spin- 1 deuterium nuclei and the electric field gradients created by chemical bonds, are affected by rapid random molecular motions that modulate the orientation of the molecule with respect to the external magnetic field. In biological and model membrane systems, where a distribution of dynamically averaged anisotropies (quadrupolar splittings, chemical shift anisotropies, etc.) is present and where, in addition, various parts of the sample may undergo a partial magnetic alignment, the numerical analysis of the resulting Nuclear Magnetic Resonance (NMR) spectra is a mathematically ill-posed problem. However, numerical methods (de-Pakeing, Tikhonov regularization) exist that allow for a simultaneous determination of both the anisotropy and orientational distributions. An additional complication arises when relaxation is taken into account. This work presents a method of obtaining the orientation dependence of the relaxation rates that can be used for the analysis of the molecular motions on a broad range of time scales. An arbitrary set of exponential decay rates is described by a three-term truncated Legendre polynomial expansion in the orientation dependence, as appropriate for a second-rank tensor interaction, and a linear approximation to the individual decay rates is made. Thus a severe numerical instability caused by the presence of noise in the experimental data is avoided. At the same time, enough flexibility in the inversion algorithm is retained to achieve a meaningful mapping from raw experimental data to a set of intermediate, model-free