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Biomedical subjects

W F Harris

Publications and source records attributed to W F Harris.

At least 109 records · Page 6Linked to original sources
PubMed1989

The second fundamental form of a surface and its relation to the dioptric power matrix, sagitta and lens thickness.

The dioptric power matrix of a single refracting surface is shown to be directly related to the differential form known in differential geometry as the second fundamental form. Consequently it is a complete description of the local refractive character of the surface. Generalized equations are derived for sagitta and lens thickness for surfaces of any form. The equations hold approximately for points close to the optical axis except in the case of paraboloidal surfaces: for paraboloidal surfaces they hold exactly. Lens thickness approximately obeys what is termed the principle of form independence. The value of the second fundamental form is approximately double the sagitta. Formal support is provided for Keating's concept of a generalized matric vergence of astigmatic wave-fronts.

Lenses↗
PubMed1988

Algebra of sphero-cylinders and refractive errors, and their means, variance, and standard deviation.

Sphero-cylinders and refractive errors can be represented by matrices. Matrix algebra provides methods whereby sphero-cylinders can be added, subtracted, multiplied, inverted, and raised to powers and can have roots extracted. These operations are defined for sphero-cylinders and examples are given. In terms of these operations a number of means of refractive errors are defined: the arithmetic, harmonic, and quadratic means. Furthermore it is possible to define a variance and standard deviation for refractive errors. These quantities should provide a basis for a formal approach to the statistical analysis of populations of refractive errors.

Humans↗
PubMed1977

The topology of hair streams and whorls in man, with an observation on their relationship to epidermal ridge patterns.

Hair slope, whorl, cross and field formation is expressible in a topological form. The mathematical description required suggests an origin for the patterns in a growth process occurring in the upper dermis which determines the patterns of the hair slope. The formulae proposed by Euler, Poincaré and Ludwig are adopted as a descriptive method for the analysis of hair patterning resulting from hair slope. A unitary theory for hair streams and fingerprint patterns is suggested by the discovery, on one remarkable human foetus, of sites where epidermal ridges and convergent hair whorls were combined. Placement of the parietal scalp whorl in man is linked to hominid brain and skull development, and its associated hair field is noted to be bipartite, as revealed through patterns of differential hair loss.

Dermatoglyphics↗
PubMed1977

Modeling and computer stimulation approach to the mechanism of foot-and-mouth disease virus neutralization assays.

Block neutralization data since 1949 for the foot-and-mouth disease virus system have been analyzed in terms of a unified mass-action theory for computing the amounts of infectious complexes. Proof that infectious complexes contribute considerably to the assays was obtained by demonstrating a reduction in titer after an additional reaction with anti-Ig antibody before the assay. In the suckling-mice assay with intraperitoneal inoculation, both the data of others and our own on several types indicate that for IgG probably three of the unknown total number of critical sites on the virion must be available for infectivity and death. For IgM, just one of an unknown different total number of critical sites on the virion must be available. In tissue culture infectivity assays the minimum number is two or three, whereas in the bovine tongue assay it could be one or two, but probably two. The difficulties in establishing the at present unknown total numbers of neutralization sites to both IgG and IgM are considerable. However, by the simplest interpretation of the data, the number is estimated to be between 5 and 10 for IgG and perhaps just 1 for IgM. A speculation, consistent with the known virion architecture, is that just 1 of the 12 vertices is uniquely involved in infectivity and death, at least in the suckling-mice assay.

Animals↗
PubMed1977

Gliding edge dislocations and flipping in the conformational change of helical proteins.

The general problem of transconformation of one helical form of protein to another is considered from a topological point of view. A notation is presented which reflects the topology of the bonding. Any helix belongs to one of two geometrical classes, the positive and negative classes. The fundamental mechanism of transconformation between helices of the same class is the edge dislocation. It has two limiting modes of propagation: glide and climb. The first appears as a caterpillar-like wave of slip that travels along the peptide chain. If the second occurs then it would be the vehicle of change in number of peptide chains. The fundamental mechanism of transconformation between molecules of opposite classes is a process we call flipping, which also probably travels as a wave. Examples of transconformation including alpha DL leads to pi 4 DL in poly-gamma-benzyl-glutamate and alpha leads to beta in keratin, are discussed.

Chemical Phenomena↗
PubMed1975

Metaldehyde poisoning in three horses.

Three horses exhibited nervous and cardiopulmonary signs after ingestins small amounts of metaldehyde, and 2 died in 3 to 5 hours. A colt given 0.1 mg/kg was similarly affected and died.

Acetaldehyde↗