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Biomedical subjects

P L Evans

Publications and source records attributed to P L Evans.

8 recordsLinked to original sources
PubMed2006

A pilot study in the application of texture relief for digitally designed facial prostheses.

This pilot research aims to identify and assess suitable technologies that may be used to capture, create, and produce fine textures and wrinkles that may be incorporated into computer aided prosthesis design and production techniques. A range of suitable technologies is identified and two methods that may be used in different prosthetic rehabilitation situations are assessed: the creation of three-dimensional relief in a computer aided design environment and the capture of facial anatomy and texture using fringe-projection surface scanning. Patterns were produced using the suitable rapid prototyping processes identified, and these were assessed by a qualified and experienced prosthetist. The suitability of the technologies is commented upon, limitations discussed, and future directions identified.

Computer Simulation↗
PubMed2004

Titanium plate reconstruction of the osseous defect after harvest of a composite free flap using the deep circumflex iliac artery.

Hernia formation following harvest of bicortical iliac crest bone occurs infrequently as a late complication and may lead to chronic pain at the donor site and rarely to obstruction and strangulation of bowel. We describe the use of a custom-made titanium plate used to reconstruct the iliac donor site following harvest of a DCIA composite free flap. A pre-operative 3D CT and stereolithography model of the ilium are used to fabricate a titanium plate of the desired shape and size. This plate is used to reconstruct the donor site defect at the time of primary surgery. This technique may reduce late complications following DCIA composite free flap harvest.

Bone Plates↗
PubMed1996

Synthesis, structure-activity relationships, and pharmacokinetic properties of dihydroorotate dehydrogenase inhibitors: 2-cyano-3-cyclopropyl-3-hydroxy-N-[3'-methyl-4'-(trifluoromethyl)phenyl ] propenamide and related compounds.

The active metabolite (2) of the novel immunosuppressive agent leflunomide (1) has been shown to inhibit the enzyme dihydroorotate dehydrogenase (DHODH). This enzyme catalyzes the fourth step in de novo pyrimidine biosynthesis. A series of analogues of the active metabolite 2 have been synthesized. Their in vivo biological activity determined in rat and mouse delayed type hypersensitivity has been found to correlate well with their in vitro DHODH potency. The most promising compound (3) has shown activity in rat and mouse collagen (II)-induced arthritis models (ED50 = 2 and 31 mg/kg, respectively) and has shown a shorter half-life in man when compared with leflunomide. Clinical studies in rheumatoid arthritis are in progress.

Acrylamides↗
PubMed1984

A classroom rating scale for use with mentally retarded children.

A behaviour rating scale intended primarily for use with mentally retarded children is described that is based on the behavioural descriptions of such children given by Pevsner (1963). A factor analysis showed that these descriptions could be viewed as being representable by two independent factors. The first of these factors, the AD factor may be seen to relate to attention/distractibility aspects of behaviour and shows a reliable correlation with verbal age and verbal quotient as assessed by the English Picture Vocabulary Test (EPVT), such that low EPVT scores predict greater distractibility. The second factor, the inhibition/excitation (IE) factor, did not correlate significantly with verbal age or verbal quotient but has, in other studies, shown relationships with style of social interaction and may be interpreted as relating to aspects of temperament. It is concluded that individual differences in the classroom behaviour of mentally retarded children may not be qualitatively different from those in non-retarded children and that the scale described is a useful instrument for measuring these individual differences.

Adolescent↗
PubMed1975

Stimulus generalization following extra-dimensional training in educationally subnormal (severely) children.

The use of discrimination learning paradigms in the study of attentional transfer is discussed. The technique of go/no-go discrimination learning followed by stimulus generalization testing is contrasted with the more familiar simultaneous learning paradigm followed by a shift in the relevant cues. In the former paradigm the effect of training a discrimination on one dimension on the slope of the stimulus generalization gradient on an independent gradient dimension (extra-dimensional training) is assessed. A steepening of the gradient relative to appropriate control procedures is taken as evidence of positive attentional transfer. The relevance of the technique to the detailed study of attentional transfer in educationally subnormal (severely) (ESN(S)) children is considered. In Expt. I nine ESN(S) children were trained in a go/no-go discrimination involving stimuli differing in orientation, and were generalization tested on a dimension that was orthogonal, namely hue. Of the six subjects who learnt the discrimination five showed clear decremental gradients on the hue dimension. In contrast a Pseudo-Discrimination group (PD) of eight subjects matched to those in the TD group showed no gradients. These subjects were not trained in the orientation discrimination, but were reinforced for responding on 50 per cent of each of the S+ and S- stimulus presentations. They thus received equal exposure to, but no differential training on, the orientation dimension. An S+ only group of four subjects who received no exposure to the orientation stimuli showed no gradients when stimulus generalization testing on the hue continuum was carried out. The result is discussed in terms of transfer deriving from stimulus control by relational aspects of the stimuli; in terms of control by constant irrelevant stimuli; and in terms of the study of stimulus control in ESN(S) children. In Expt. II the influence of the codability of the colours on the location of the peak of the stimulus generalization gradients in the TD group is investigated.

Adolescent↗