Biomedical subjects
A Lawther
Publications and source records attributed to A Lawther.
Risk factors for hepatitis B at a residential institution for intellectually handicapped persons.
We conducted a cross sectional study to evaluate risk factors for hepatitis B (HBV) infection among residents and staff at Braemar Hospital in Nelson. We obtained serum and abstracted medical charts for 114 of the 122 (93%) residents; 129 of 226 (57%) staff members completed questionnaires and provided serum. Seventy (61%) of the residents had serological markers of past HBV infection, including 42 (37%) who were identified as carriers. Residents' risk of being infected increased by 17% for each additional year they had lived in this institution; there were no significant differences in the likelihood of having markers of HBV infection by a person's age at first admission, sex, ethnicity, admission diagnosis, medical history, or various behavioural attributes. Among staff, 20 (16%) showed evidence of past exposure to HBV, but none were identified as being carriers; of these, 5 (25%) reported having received hepatitis B vaccine. Excluding the vaccinated persons who were seropositive, there were no demographic or occupational risk factors that were significantly associated with having serological markers of past HBV exposure. To control further HBV transmission in this setting, all current and future residents, as well as staff members who have direct contact with residents, should be screened for serological markers of HBV and persons identified as being susceptible should be vaccinated.
Motion sickness and motion characteristics of vessels at sea.
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A survey of the occurrence of motion sickness amongst passengers at sea.
A questionnaire survey of motion sickness occurrence on board passenger ferries has been conducted. Data were collected from 20,029 passengers on 114 voyages on 9 vessels: 6 ships, 2 hovercraft, and 1 jetfoil. Information was obtained about feelings of illness, the occurrence of vomiting, the taking of anti-seasickness tablets, the consumption of alcoholic drinks, regularity of travel by sea, age, and sex. Overall, 7% of passengers reported vomiting at some time during the journey, 21% said they felt "slightly unwell," 4% felt "quite ill," and a further 4% felt "absolutely dreadful." Both vomiting incidence and illness rating were greater in females than in males, and there was a slight decrease in sickness occurrence with increasing age. The incidence of vomiting was related to the taking of tablets and the drinking of alcohol; there were also some interaction effects with other variables. Anecdotal information from passengers is reported and consideration is given to the effects of environmental variables.
Prediction of the incidence of motion sickness from the magnitude, frequency, and duration of vertical oscillation.
A method is proposed by which the incidence of motion sickness may be predicted from measurement of the motion exposure. The method is based on data from both field and laboratory studies involving large numbers of people and is applicable to marine and other environments where vertical oscillation occurs at frequencies below 0.5 Hz. The dependence of motion sickness on the frequency of oscillation requires the use of a weighting function between 0.1 and 0.5 Hz. The dependence of sickness on the duration of exposure is incorporated by the use of a cumulative measure of motion dose based on the product of root-mean-square (rms) acceleration magnitude and the square root of stimulus duration. The influence of population variables such as sex, age, and motion experience is discussed. The method enables separate predictions to be made of vomiting incidence and of feelings of illness. The prediction procedure, while not seeking to explain the underlying mechanisms of motion sickness occurrence, provides a generally applicable method which is simple to use and has an accuracy consistent with the experimental data on which it is based.
The motion of a ship at sea and the consequent motion sickness amongst passengers.
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Integrated system for the purchase, distribution, and use of drugs in hospital.
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