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Biomedical subjects

D Kault

Publications and source records attributed to D Kault.

6 recordsLinked to original sources
PubMed2000

Uncertainties in predicting the demographic impact of AIDS.

A model giving the demographic impact of AIDS is analysed to examine the sensitivity of the projections when various complicating features are included. The model deals with age and sexual partner change rate as continuous variables and uses a device to specify arbitrary correlations between the ages of the people who form sexual partnerships. The device ensures consistency, in that the amount of partner formation is the same regardless of whether the partnerships are counted from the point of view of males or females. Arbitrary correlation between partner change rate and fertility is also permitted. The results show the uncertainty in model predictions that population growth will reduce over the next 20 years to approximately zero in parts of East Africa severely affected by the AIDS epidemic. The main sources of uncertainty in the model predictions are assumptions concerning the correlation between ages in a partnership, the correlation between partner change rate and fertility, the incubation period of AIDS, and the variability of the female partner change rate.

Acquired Immunodeficiency Syndrome↗
PubMed1996

The shape of the distribution of the number of sexual partners.

Information on the number of sexual partners that people have is necessary for predicting the likely long term course of the AIDS epidemic. More information is required than is provided by simply stating the mean and variance of the number of partners. It is useful to find a family of curves which approximate data on the proportion of people in the various 'number of partners' categories. Two Australian surveys of the sexual behaviour of first year university behavioural science students were analysed. It was found here that log-normal distributions gave good approximations to the distribution of number of partners amongst people who had more than one partner. Gamma and negative binomial distributions gave less satisfactory fits and the truncated normal and Poisson distributions were clearly unable to match the data.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Assessing the National HIV/AIDS Strategy evaluation.

The report is a useful compilation of data on Australia's HIV/AIDS epidemic and the response to it. The report produces firm evidence for endorsing Australia's success in limiting the spread of HIV by a number of routes. Australia has been successful in preventing iatrogenic spread, spread through commercial sex and spread through injecting drug use. In the latter case however, the hepatitis C epidemic cautions against complacency. The report, unfortunately, does not recognise very serious weaknesses in the evidence it uses as a basis for its endorsement of current efforts against HIV in the male homosexual community and the general heterosexual community. The report recognises failure of current policies in Aboriginal and Torres Strait Islander communities and recognises the threat posed here by HIV but recommends no major policy change. There is some recognition of the limitation of the data, but no recommendation for increased surveillance. The report ignores methods of prevention other than public health education. In my view, there is sufficient evidence to recommend routine neonatal circumcision, at least in Aboriginal and Torres Strait Islander communities. There is a clear need for a more effective approach to STD control, particularly in these communities. Adequate STD and HIV control may well require contact tracing and surveillance using traditional public health methods. Measurement of objective indicators of the success of HIV prevention campaigns needs to be improved with more comprehensive collection of data on HIV and STD incidence and condom sales, stratified by relevant covariates. Survey evidence of behavioural change should be collected from those too young to be affected by the selective mortality factor. The international comparisons await a proper statistical study which may be able to identify the elements of an effective approach to AIDS. In future reviews of the effectiveness of Australia's response to AIDS, all methods of limiting the spread of the epidemic should be considered objectively. It is unacceptable for the AIDS program to be declared optimal simply because it accords with current public health ideology.

Australia↗
PubMed1991

Moving muscles with microchips, mathematics and models: an update on the 'reverse' model.

This paper reviews the current status of our computer model for the management of strabismus and its future direction. Vector analysis was first used in the 1950s for the assessment of strabismus. Robinson's model was the first computer simulation of ocular motility. Using physiological principles and anatomical approximations, Robinson's model sought to predict the strabismic pattern to be expected from a given injury. The Kault/Stark 'reverse' model works in the opposite direction, to first simulate the given strabismic pattern and then advise the surgery required to restore orthophoria. The surgeon is able to 'trial' various operations and compare the expected postoperative results. An automated system is currently being developed to ease the difficulty in measuring the position of the eyes in all nine positions of gaze. This paper includes three illustrative case reports.

Adolescent↗
PubMed1989

An automated system of strabismus management. A direct approach using a "reverse" model.

Until now computer models of strabismus have consisted of lengthy calculations based on oculomotor physiology. Such models have been able to demonstrate the pattern of strabismus that would arise from any given muscle abnormality and/or operation. However, it has been difficult to use such models to guide strabismus surgery because the surgeon requires a model that works in the opposite direction. The surgeon requires a model whose input is the pattern of strabismus and output is the muscle operation required. Such a model is described here. Instead of consisting of calculations based on physiology the new model consists of a store of most of the information capable of being generated by an existing strabismus model together with an efficient search procedure. In this paper the potential of the new model is demonstrated by its application to a case of paralytic strabismus.

Diagnosis, Computer-Assisted↗