Biomedical subjects

N M Allinson

Publications and source records attributed to N M Allinson.

3 recordsLinked to original sources

PubMed2000

Integration of macromolecular diffraction data using radial basis function networks.

This paper presents a novel approach for intensity calculation of X-ray diffraction spots based on a two-stage radial basis function (RBF) network. The first stage uses pre-determined reference profiles from a database as basis functions in order to locate the diffraction spots and identify any overlapping regions. The second-stage RBF network employs narrow basis functions capable of local modifications of the reference profiles leading to a more accurate observed diffraction spot approximation and therefore accurate determination of spot positions and integrated intensities.

Journal Article↗

PubMed1995

On the distribution and convergence of feature space in self-organizing maps.

In this paper an analysis of the statistical and the convergence properties of Kohonen's self-organizing map of any dimension is presented. Every feature in the map is considered as a sum of a number of random variables. We extend the Central Limit Theorem to a particular case, which is then applied to prove that the feature space during learning tends to multiple gaussian distributed stochastic processes, which will eventually converge in the mean-square sense to the probabilistic centers of input subsets to form a quantization mapping with a minimum mean squared distortion either globally or locally. The diminishing effect, as training progresses, of the initial states on the value of the feature map is also shown.

Algorithms↗

PubMed1994

Development of Non-Intensified Charge-Coupled Device Area X-ray Detectors.

Area X-ray detectors based on charge-coupled device imagers can provide excellent performance in terms of spatial resolution, sensitivity and dynamic range. Improvements in the fabrication of the primary converter, either scintillator or phosphor, mean that it is becoming possible to dispense with prestorage intensifiers and still provide outstanding low-level signal performance. Structured CsI scintillators are presented as one method of providing high efficiency and excellent spatial resolving power for this primary converter. Characterization of detector performance, in terms of such parameters as the detective quantum efficiency, point-spread function and dynamic range, needs to be directly related to the specific application of the detector. This contribution emphasizes the interplay of these parameters in the optimum design of detector systems. Performance prediction, based on measurements taken from prototype development systems, illustrates how such detectors will meet the exacting requirements of macromolecular crystallography.

Journal Article↗