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Biomedical subjects

A Rogers

Publications and source records attributed to A Rogers.

At least 109 records · Page 6Linked to original sources
PubMed1995

Laterality of visuo-spatial attention in acute and chronic schizophrenia, major depression and in healthy controls.

Previous studies have suggested that schizophrenia is characterized by an asymmetry of visuo-spatial attention, in particular that acute unmedicated schizophrenics demonstrate relative inattention to right hemispace, whereas chronically medicated patients demonstrate the opposite pattern. In the present study, 30 unmedicated schizophrenic patients, 32 chronically medicated schizophrenic patients, 30 patients suffering from major depression and 60 healthy controls were assessed using two measures of hemispatial attentional neglect, namely letter and star cancellation. The results demonstrated that the chronic schizophrenic group made more total omissions for star cancellation (in both right and left hemispace), but that there was no difference between the groups in terms of omission asymmetry for either letter or star cancellation.

Adult↗
PubMed1995

Population forecasting: do simple models outperform complex models?

"This paper reviews the growing literature on population forecasting to examine a curious paradox: despite continuing refinements in the specification of models used to represent population dynamics, simple exponential growth models, it is claimed, continue to outperform such more complex models in forecasting exercises. Shrinking a large complex model in order to simplify it typically involves two processes: aggregation and decomposition. Both processes are known to introduce biases into the resulting representations of population dynamics. Thus it is difficult to accept the conclusion that simple models outperform complex models. Moreover, assessments of forecasting performance are notoriously difficult to carry out, because they inevitably depend not only on the models used but also on the particular historical periods selected for examination.... This paper reviews some of the recent debate on the simple versus complex modeling issue and links it to the questions of model bias and distributional momentum impacts." (SUMMARY IN FRE)

Demography↗
PubMed1995

Health status and exposure of workers at a pilot brown coal liquefaction plant in Australia, 1985-1991.

In 1985, Brown Coal Liquefaction (Victoria) Pty Ltd (BCLV) commenced operation of a pilot plant that investigated the feasibility of producing oil from brown coal. The plant operated for five years. This study aimed to use exposure and health information routinely collected by the company to characterize various health parameters of the workforce and to investigate whether any adverse health measures were exposure-related. About 1680 persons were employed at some time or other by BCLV, and the primary study population consisted of 408 workers who had a medical examination at the end of employment and who consented to being in an epidemiological study. Reported photosensitivity was associated with higher cumulative skin exposure (RR = 1.85; 95% CI = 1.22-2.78), with an exposure-response relationship of increasing risk with increasing skin exposure being suggested. There was no consistent evidence that chemical exposure at BCLV had any negative effect on the haematological, biochemical, endocrine or lung function of workers at the plant. However, the maximum follow-up period of less than eight years limits the ability of the study to detect any emerging chronic effects.

Adult↗
PubMed1995

Mass childhood immunization: some ethical doubts for primary health care workers.

The mass childhood immunization programme has traditionally been viewed as a safe and effective preventative measure by health promoters, primary health care professionals and governments. This consensus has meant that immunization has rarely been viewed as ethically problematic. A number of recent changes in the context of the delivery of health care, particularly the emphasis on consumerism and the effect of the marketization of services, makes timely an examination of ethical, social and political issues. This article examines four main grounds for problematizing the mass childhood immunization programme. These are: clinical research evidence about the safety and efficacy of vaccines; the masking of wider social and political determinants of ill health; the contradictory strictures about collective and individual rights in relation to immunization; and the uniqueness of childhood immunization as a physical intrusion into a healthy body. The implications of these ethical issues are discussed in relation to informed consent and the need for a 'greenfield' review that includes the views of dissenting parents, lawyers and moral philosophers, as well as health professionals.

Child↗
PubMed1995

Occupational and environmental mesotheliomas due to crocidolite mining activities in Wittenoom, Western Australia.

OBJECTIVES: The aim of the study was to review existing cases, calculate rates, and predict future numbers of occupational and environmental mesotheliomas from Wittenoom. METHODS: On the basis of information contained in occupational and environmental histories, Wittenoom cases were extracted from national records collected since 1979. Occupational and residential population estimates were obtained from company and government records. The proportional latency method was used to predict the numbers of mesotheliomas prior to and after the data collection phase. Airborne fiber monitoring was used to calculate risk due to current levels of contamination in the mine and town environments. RESULTS: During 1979-1994, Wittenoom cases (N = 176) comprised approximately 6% of the mesothelioma cases recorded in Australia. Of these 122 were employed directly in the mining and milling activities, another 18 were involved in the transport of raw fiber or tailings, and 34 were town residents or visitors. Due to past exposures, additional occupational (N = 301) and environmental (N = 83) cases can be expected. Dependent on residential time, existing levels of contamination may result in a risk of between < 1 to 57 per million of the population. CONCLUSIONS: Latency effects will result in considerable numbers of mesotheliomas appearing over the next 10-20 years in Wittenoom. The cessation of mining activities and major clean up of the town will result in reduced mesothelioma cases.

Adolescent↗
PubMed1995

An open trial of venlafaxine in adult patients with attention deficit hyperactivity disorder.

Stimulant medications are the most widely accepted treatment of attention deficit hyperactivity disorder (ADHD) in spite of controversy over their use. Stimulants have consistently been shown to potentiate noradrenergic brain transmission, a property also characteristic of the recently marketed antidepressant venlafaxine. Eighteen adults who met the Utah Criteria for ADHD in adults were enrolled in an open trial of venlafaxine. Progress was monitored with a recently refined rating scale designed to measure change in adult patients with ADHD. Among the 11 patients who could tolerate the medication, 8 showed a good response that was well maintained. They responded to dosages of 50 to 150 mg/day, with an average dose of 96 mg. Seven of the 18 had difficulty tolerating venlafaxine's side effects. These data suggest that controlled trials should be conducted with venlafaxine for ADHD.

Adult↗
PubMed1994

Parameterizing age patterns of demographic rates with the multiexponential model schedule.

"For nearly 200 years actuaries, statisticians, and demographers have sought to summarize the age pattern of mortality rates by means of a limited number of parameters. Such 'model schedules' have also been useful in representing schedules of rates other than mortality....This paper illustrates a particular general functional form for such model schedules: the multiexponential function. It discusses the changing behavior of this function as its parameters take on different values and examines the quality of the fits of this function to observed data on mortality, fertility, and migration." This is a revised version of a paper originally presented at the 1993 Annual Meeting of the Population Association of America. (SUMMARY IN FRE)

Demography↗
PubMed1994

Luria-Delbrück fluctuation experiments: design and analysis.

Luria and Delbrück, in a seminal paper, introduced fluctuation analysis primarily as a means to elucidate the timing of mutation in relation to the imposition of selective conditions. Their work, and subsequently that of LEA and COULSON, established also a basis for measuring the frequency of mutational events. The several estimators proposed by these authors differ both in complexity and in efficiency, and the published literature relies mainly on the less efficient but computationally trivial estimators. The estimators as originally proposed assume that all mutants occurring in culture will be counted in the subsequent assay, but a relaxation of this assumption suggests an alternative experimental design and alternative estimators which offer advantages over those currently in common use.

Biometry↗
PubMed1994

Performance of glass fiber antiscatter devices at mammographic energies.

Using fiber optic manufacturing techniques, it is possible to produce a radiographic grid that discriminates against scattered radiation in two dimensions. Such grids consist of septa composed of glass with a high lead content; the interspace material is air, so that approximately 80% of the grid area is open. In this way, effective high ratio grids can be produced with relatively low Bucky factors. The performance of samples of such grid material is characterized in terms of both scatter rejection and dose efficiency for application in digital mammography in both slot-beam and area-beam geometry. For area beams, five- to tenfold improved scatter rejection relative to conventional grids was observed. In slot configurations, such grids could provide improved SNR/dose performance and more effective utilization of the heat loading capability of the x-ray source.

Fiber Optic Technology↗
PubMed1994

Measuring handicap: the London Handicap Scale, a new outcome measure for chronic disease.

OBJECTIVE: To develop a handicap measurement scale in a self completion questionnaire format, with scale weights allowing quantification of handicap at an interval level of measurement. DESIGN: Adaptation of the International Classification of Impairments, Disabilities and handicaps into a practical questionnaire incorporating the dimensions of handicap mobility, occupation, physical independence, social integration, orientation, and economic self sufficiency and scale weights derived from interviews with a general population sample, with the technique of conjoint analysis. SETTING: Two general practices in different areas of London. SUBJECTS: 240 adults aged 55-74 years randomly selected from the practices, 101 (42%) of whom agreed to be interviewed, and 79 (78%) of whom completed the exercise. MAIN MEASURES: Rating of severity of handicap associated with 30 hypothetical health scenarios on a visual analogue scale, from which was derived a matrix of scale weights ("part utilities") relating to different levels of disadvantage on each dimension, with a formula for combining them into an overall handicap score. Severity scores measured directly for five scenarios not used to derive the scale weights were compared with those calculated from the formula to validate the model. RESULTS: The part utilities obtained conformed with the expected hierarchy for each dimension, confirming the validity of the method. The measured severities and those calculated from the formula for the five scenarios used to validate the model agreed closely (Pearson's r = 0.98, p = 0.0009; Kendall's tau = 1.00, p = 0.007). CONCLUSIONS: This interval level handicap measurement scale will be useful in assessing both specific therapies and health services, in clinical trials, in analyses of cost effectiveness, and in assessments of quality assurance.

Activities of Daily Living↗