Biomedical subjects

M M Turner

Publications and source records attributed to M M Turner.

4 recordsLinked to original sources

PubMed2006

Collisionless heating in capacitive discharges enhanced by dual-frequency excitation.

We discuss collisionless electron heating in capacitive discharges excited by a combination of two disparate frequencies. By developing an analytical model, we find, contrary to expectation, that the net heating in this case is much larger than the sum of the effects occurring when the two frequencies act separately. This prediction is substantiated by kinetic simulations, which are also in excellent general quantitative agreement with the model for discharge parameters that are typical of recent experiments.

Journal Article↗

PubMed2001

Collisionless electron heating by capacitive rf sheaths.

High-frequency plasma discharges are often sustained by collisionless heating of electrons; the nature of these mechanisms is a central problem in the theory of such discharges. In capacitive discharges, collisionless heating occurs near boundaries, and is usually attributed to inelastic collisions of electrons with oscillating plasma sheaths, regarded as moving rigid barriers. We show that, when current conservation is required, such heating necessarily vanishes, and we conclude that this model of the heating process is not correct. We develop an alternative view that associates the heating with acoustic disturbances in the electron fluid. An analytic model, based on moments of the Vlasov equation, gives results in good agreement with particle-in-cell simulations. In terms of individual particle dynamics, this acoustic heating may be interpreted as a transit-time effect.

Journal Article↗

PubMed1996

An audit of velopharyngeal incompetence treated by the Orticochea pharyngoplasty.

An audit of patients with velopharyngeal incompetence treated by the Orticochea pharyngoplasty was undertaken. 54 patients who had been treated by a single surgeon over a 10-year period were identified. All patients had pre- and postoperative speech therapy and were followed up for an average of 6 months. 49/54 patients had lessening of their nasal escape; in 40/54 it was eliminated completely. Nasal resonance was assessed as normal in 46/54 of patients postoperatively. The results are compared with those of other similar studies.

Adolescent↗

PubMed1988

A study to assess the effectiveness of a professional and lay support service for parents of new-born cleft babies.

Since 1981 the Leicestershire Support Service has offered a combination of professional and lay advice to parents of new-born cleft babies. This paper evaluates this service by interviewing retrospectively the parents of two groups of children, those born before the service was available and those born since. As a control group, a prospective study of parents with unclefted children was carried out. The strengths and weaknesses of the current Support Service are identified and recommendations for improvements are proposed.

Attitude to Health↗