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Biomedical subjects

I D Brown

Publications and source records attributed to I D Brown.

14 recordsLinked to original sources
PubMed1991

The initial use of a computer-controlled expert system in the treatment planning of Class II division 1 malocclusion.

A computer based expert system for providing orthodontic advice for Class II Division 1 malocclusion has been developed and evaluated. Treatment plans produced by the system for 31 non-prior approval cases drawn from material provided by the Dental Practice Board were compared with the treatments actually carried out by the practitioners. The shortcomings of the system are discussed.

Decision Trees↗
PubMed1989

Assessing one's own and others' driving ability: influences of sex, age, and experience.

Observational studies of drivers' involvements in dangerous situations suggest that young males drive differently from other road users. Studies of drivers' assessments of their own ability appear to show that they believe they drive better than their peers and that, while young males equate their ability with that of older male drivers, the latter group see themselves as superior to their younger counterparts but of equivalent ability to peers. It is unclear from previous studies what the influence of driving experience is on such assessments and, indeed, what female drivers feel about their ability. The present studies suggest that the widely reported tendency for people to overestimate their ability may be largely artifactual, that males and females describe their performance similarly, and that previously reported age differences disappear when driving experience is controlled. Among the differences that remain is the reported greater "recklessness" and comparative lack of "smoothness" of young males' driving. The implications of these findings for our understanding of risk assessment and acceptance are discussed.

Adult↗
PubMed1989

The closure of residual extraction spaces by means of traction screws: a report of two cases.

In those cases judged to be suitable for treatment by extractions in both arches and the use of upper removable appliances alone, the closure of excess residual space relies on mesial drift of the buccal segments. If opposing residual spaces are unequal in extent, there is a risk that space closure will be incomplete. Two cases are presented where a removable appliance was used to move a buccal segment mesially using a traction screw, and thereby close the excess residual space.

Adolescent↗
PubMed1985

Changes in lipid fluidity and fatty acid composition with altered culture temperature in Tetrahymena pyriformis-NT1.

Cultures of T. pyriformis-NT1 were grown at 20 degrees C (Tg 20 degrees C) and 38 degrees C (Tg 38 degrees C). G.L.C. analysis and D.P.H. fluorescence polarization measurements in extracted phospholipids indicated that there was increased saturation of fatty acids and relatively reduced fluidity as growth temperature was increased. Breakpoints occurred in the Arrhenius plots of fluorescence polarization at 16 degrees C for Tg 38 degrees C total extracted phospholipids and 9 degrees C for Tg 20 degrees C lipids.

Animals↗
PubMed1985

The effects of temperature upon the electrophysiological properties of Tetrahymena pyriformis-NT1.

Cells of Tetrahymena pyriformis--NT1 were cultured at 38 degrees C (Tg 38 degrees C) and 20 degrees C (Tg 20 degrees C) and their properties investigated over the range 0-40 degrees C. Tg 20 degrees C cells were viable in the range 3-33 degrees C and changes in their properties were readily reversible between 10 degrees C and 30 degrees C. Tg 38 degrees cells were viable in the range 40-10 degrees C and their property changes were immediately reversible in the range 40-23 degrees C. The I-V relations of Tg 38 degrees C cells showed increased excitability as the cells were cooled from 40 degrees C. At 10 degrees C there was a considerable loss of excitability and slope resistance. Cooling Tg 20 degrees C cells from 20 degrees C gave a similar pattern, although over a narrower temperature range. Warming Tg 20 degrees C Tetrahymena above 20 degrees C led to a progressive loss of excitability and the cells were markedly less viable above 35 degrees C. Within physiological limits the regenerative spike magnitude, repolarization time, time to peak and input resistance increased as temperature was lowered, whereas resting potential was diminished. When compared at their growth temperatures and most intermediate temperatures, the value of the various parameters monitored were generally different for the two cultures. The Q10 value for resting potential changes of Tg 20 degrees C cells about 20 degrees C was 1.20. As in T. vorax this was significantly (P less than 0.01) greater than that predicted for a diffusion potential and suggested that T. pyriformis--NT1 may have an electrogenic pump component in its membrane potential.

Animals↗
PubMed1985

Temperature-dependent changes in the swimming behaviour of Tetrahymena pyriformis-NT1 and their interrelationships with electrophysiology and the state of membrane lipids.

The swimming velocity and the amplitude of the helical swimming path of T. pyriformis-NT1 cells grown at 20 degrees C (Tg 20 degrees C) and 38 degrees C (Tg 38 degrees C) were monitored between 0 and 40 degrees C in the presence and absence of electric fields. Within physiological limits the swimming velocity increased and the amplitude decreased as temperature was raised. The temperature profiles of these properties were not linear, and showed discontinuities at different temperatures for the different cultures. The break points in Arrhenius plots of the resting potential, regenerative spike magnitude, repolarization time, swimming velocity and swimming amplitude are tabulated and compared. The initial breakpoints upon cooling were clustered about the breakpoints in fluorescence polarization of D.P.H. in extracted phospholipids, and around the transition temperatures estimated from the literature for the pellicular membrane of these cells. The average of the initial breakpoints on cooling was 22.9 degrees C for Tg 38 degrees C cells and 13.7 degrees C for Tg 20 degrees C cells, a shift of 9.2 degrees C. Unlike Paramecium there is no depolarizing receptor potential in Tetrahymena upon warming. It is suggested that this may be the basis of a behavioural difference between Tetrahymena and Paramecium--namely that in Tetrahymena maximum swimming velocity occurs above growth temperature whereas in Paramecium the two points coincide. Swimming velocity and resting potential were correlated with membrane fluidity within physiological limits, but for other parameters the relationship with fluidity was more complex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1975

A life-span look at person perception and its relationship to communicative interaction.

Two experiments were conducted in order to discover (a) the expressed attitudes of young adults about the intellectual abilities of seven target groups ranging in age from infant to elderly, and (b) if and in what manner young adults differentially explain the rules of a simple game to these same target groups. In Experiment I, questionnaires requiring the attribution of intellectual capabilities of infants, preschoolers, preadolescents, adolescents, and young and middle-aged, and elderly adults were completed by 243 subjects. Intellectual ability was seen as increasing with age until old age. The elderly were consistently perceived as less competent than both young and middle-aged adults. The result of Experiment II, in which 60 subjects participated, suggested that young adults modify the complexity of their communications to different aged listeners in accordance with their expressed perceptions of the intellectual attributes of their auditors.

Adolescent↗