What is a healthy weight for middle aged women?

OBJECTIVE: To explore associations between body mass index (BMI) and selected indicators of health and well-being and to suggest a healthy weight range (based on BMI) for middle aged Australian women. DESIGN: population based longitudinal study (cross-sectional baseline data). SUBJECTS: 13431 women aged 45-49 y who participated in the baseline survey for the Australian Longitudinal Study on Women's Health. RESULTS: Forty-eight percent of women had a BMI>25kg/m(2). Prevalence of medical problems (for example, hypertension, diabetes), surgical procedures (cholescystectomy, hysterectomy) and symptoms (for example, back pain) increased monotonically with BMI, while indicators of health care use (for example, visits to doctors) showed a 'J' shaped relationship with BMI. Scores for several sub-scales of the MOS short form health survey (SF36) (for example, general health, role limitations due to emotional difficulties, social function, mental health and vitality) were optimal when BMI was around 19-24 kg/m(2). After adjustment for area of residence, education, smoking, exercise and menopausal status, low BMI was associated with fewer physical health problems than mid-level or higher BMI, and the nationally recommended BMI range of 20-25 was associated with optimum mental health, lower prevalence of tiredness and lowest use of health services. CONCLUSIONS: Acknowledging the limitations of the cross-sectional nature of these data, the results firmly support the benefits of leanness in terms of reducing the risk of cardiovascular disease, diabetes and gall bladder disease. The findings are moderated, however, by the observation that both low and high BMI are associated with decreased vitality and poorer mental health. The optimal range for BMI appears to be about 19-24 kg/m(2). From a public health perspective this study provides strong support for the recommended BMI range of 20-25 as an appropriate target for the promotion of healthy weight in middle aged Australian women.

Moneyless business exchange - Practitioners' attitudes to business-to-business barter in Australia

In recent years, domestic business-to-business barter has become institutionalized as an alternative marketing exchange system in Australia, and elsewhere. This article reports the findings of a survey of 164 members of Australia's largest trade exchange, Bartercard There are few, if any, published empirical studies on this topic. This study is exploratory. Most firms surveyed are small firms in the services sectors. Although Bartercard has an extensive membership, trading within the system is limited with most members trading less than once per week and with barter transactions contributing less than 5% of their annual gross sales. The main benefits of membership include new customers and increased sales and networking opportunities. The main limitations include the limited functionality of the trade dollar limited trading opportunities, and practical trading difficulties. In selling, there appears to be no differential between the cash and trade prices, whereas trade dollars are discounted in purchasing. Participants acknowledge that business-to-business barter will remain and grow regardless of cyclical macroeconomic changes. (C) 1998 Elsevier Science Inc.

Health-related quality of life in Australian children with asthma: lessons for the cross-cultural use of quality of life instruments

The development of Australian forms of the Childhood Asthma Questionnaires (CAQs) is reported. Focus group methods and psychometric analyses were used to establish the conceptual, semantic and technical equivalence of these forms with the UK versions. Both versions also provide for data collection from non-asthmatic youngsters. The internal consistency was found to be acceptable (Cronbach's alpha 0.52-0.90) and the health-related quality of life (HRQoL) scores were found to vary with asthma severity (p < 0.05). Comparison with the UK data revealed that the non-asthmatic scores were higher for Australian than British children (p < 0.001) but that the scores for children with asthma did not differ between the two countries. It was only In the Australian sample that the group with asthma reported impaired HRQoL when compared to their healthy peers. These findings were interpreted in the context of cultural expectations of life quality and conclusions are presented regarding the importance of the gap between experience and expectations. The difficulties raised by the developmental and cultural issues inherent in paediatric HRQoL research were discussed. Qual. Life Res. 7:409-419 (C) 1998 Kluwer Academic Publishers

Analysis of small signal stability margins using genetic optimization

Power system small signal stability analysis aims to explore different small signal stability conditions and controls, namely: (1) exploring the power system security domains and boundaries in the space of power system parameters of interest, including load flow feasibility, saddle node and Hopf bifurcation ones; (2) finding the maximum and minimum damping conditions; and (3) determining control actions to provide and increase small signal stability. These problems are presented in this paper as different modifications of a general optimization to a minimum/maximum, depending on the initial guesses of variables and numerical methods used. In the considered problems, all the extreme points are of interest. Additionally, there are difficulties with finding the derivatives of the objective functions with respect to parameters. Numerical computations of derivatives in traditional optimization procedures are time consuming. In this paper, we propose a new black-box genetic optimization technique for comprehensive small signal stability analysis, which can effectively cope with highly nonlinear objective functions with multiple minima and maxima, and derivatives that can not be expressed analytically. The optimization result can then be used to provide such important information such as system optimal control decision making, assessment of the maximum network's transmission capacity, etc. (C) 1998 Elsevier Science S.A. All rights reserved.

A relative gradient theory for layered materials

It is possible to remedy certain difficulties with the description of short wave length phenomena and interfacial slip in standard models of a laminated material by considering the bending stiffness of the layers. If the couple or moment stresses are assumed to be proportional to the relative deformation gradient, then the bending effect disappears for vanishing interface slip, and the model correctly reduces to an isotropic standard continuum. In earlier Cosserat-type models this was not the case. Laminated materials of the kind considered here occur naturally as layered rock, or at a different scale, in synthetic layered materials and composites. Similarities to the situation in regular dislocation structures with couple stresses, also make these ideas relevant to single slip in crystalline materials. Application of the theory to a one-dimensional model for layered beams demonstrates agreement with exact results at the extremes of zero and infinite interface stiffness. Moreover, comparison with finite element calculations confirm the accuracy of the prediction for intermediate interfacial stiffness.

Reducing coronary heart disease in the Australian Coalfields: evaluation of a 10-year community intervention

Coronary heart disease is a leading cause of death in Australia with the Coalfields district of New South Wales having one of the country's highest rates. Identification of the Coalfields epidemic in the 1970's led to the formation of a community awareness program in the late 1980's (the healthy heart support group) followed by a more intense community action program in 1990, the Coalfields Healthy Heartbeat (CHHB). CHHB is a coalition of community members, local government officers, health workers and University researchers. We evaluate the CHHB program, examining both the nature and sustainability of heart health activities undertaken, as well as trends in risk factor levels and rates of coronary events in the Coalfields in comparison with nearby local government areas. Process data reveal difficulties mobilising the community as a whole; activities had to be selected for interested subgroups such as families of heart disease patients, school children, retired people and women concerned with family nutrition and body maintenance. Outcome data show a significantly larger reduction in case fatality for Coalfields men (although nonfatal heart attacks did not decline) while changes in risk factors levels were comparable with surrounding areas. We explain positive responses to the CHHB by schools, heart attack survivors and women interested in body maintenance in terms of the meaning these subgroups find in health promotion discourses based on their embodied experiences. When faced with a threat to one's identity, health discourse suddenly becomes meaningful along with the regimens for health improvement. General public disinterest in heart health promotion is examined in the context of historical patterns of outsiders criticising the lifestyle of miners, an orientation toward communal lather than individual responsibility for health (i.e, community 'owned' emergency services and hospitals) and anger about risks from environmental hazards imposed by industrialists. (C) 1999 Elsevier Science Ltd. All rights reserved.

New techniques in nutritional assessment: body composition methods

New techniques in air-displacement plethysmography seem to have overcome many of the previous problems of poor reproducibility and validity. These have made body-density measurements available to a larger range of individuals, including children, elderly and sick patients who often have difficulties in being submerged underwater in hydrodensitometry systems. The BOD POD air-displacement system (BOD POD body composition system; Life Measurement Instruments, Concord, CA, USA) is more precise than hydrodensitometry, is simple and rapid to operate (approximately 1 min measurements) and the results agree closely with those of hydrodensitometry (e.g. +/-3.4% for estimation of body fat). Body line scanners employing the principles of three-dimensional photography are potentially able to measure the surface area and volume of the body and its segments even more rapidly (approximately 10 s), but the validity of the measurements needs to be established. Advances in i.r. spectroscopy and mathematical modelling for calculating the area under the curve have improved precision for measuring enrichment of (H2O)-H-2 in studies of water dilution (CV 0.1-0.9% within the range of 400-1000 mu l/l) in saliva, plasma and urine. The technique is rapid and compares closely with mass spectrometry (bias 1 (SD 2) %). Advances in bedside bioelectrical-impedance techniques are making possible potential measurements of skinfold thicknesses and limb muscle mass electronically. Preliminary results suggest that the electronic method is more reproducible (intra-and inter-individual reproducibility for measuring skinfold thicknesses) and associated with less bias (+ 12%), than anthropometry (+ 40%). In addition to these selected examples, the 'mobility' or transfer of reference methods between centres has made the distinction between reference and bedside or field techniques less distinct than in the past.

Modelling the large deformations in stratified media - the Cosserat continuum approach

Methods employing continuum approximation in describing the deformation of layered materials possess a clear advantage over explicit models, However, the conventional implicit models based on the theory of anisotropic continua suffers from certain difficulties associated with interface slip and internal instabilities. These difficulties can be remedied by considering the bending stiffness of the layers. This implies the introduction of moment (couple) stresses and internal rotations, which leads to a Cosserat-type theory. In the present model, the behaviour of the layered material is assumed to be linearly elastic; the interfaces are assumed to be elastic perfectly plastic. Conditions of slip or no slip at the interfaces are detected by a Coulomb criterion with tension cut off at zero normal stress. The theory is valid for large deformation analysis. The model is incorporated into the finite element program AFENA and validated against analytical solutions of elementary buckling problems in layered medium. A problem associated with buckling of the roof and the floor of a rectangular excavation in jointed rock mass under high horizontal in situ stresses is considered as the main application of the theory. Copyright (C) 1999 John Wiley & Sons, Ltd.

Quantum controlled-NOT gate with 'hot' trapped ions

We present a novel method of performing quantum logic gates in trapped ion quantum computers which does not require the ions to be cooled down to the ground state of their vibrational modes, thereby avoiding one of the principal experimental difficulties encountered in realizing this technology. Our scheme employs adiabatic passages and a phase shift conditional on the phonon number state.

Estimation of contribution of changes in classic risk factors to trends in coronary-event rates across the WHO MONICA Project populations

Background From the mid-1980s to mid-1990s, the WHO MONICA Project monitored coronary events and classic risk factors for coronary heart disease (CHD) in 38 populations from 21 countries. We assessed the extent to which changes in these risk factors explain the variation in the trends in coronary-event rates across the populations. Methods In men and women aged 35-64 years, non-fatal myocardial infarction and coronary deaths were registered continuously to assess trends in rates of coronary events. We carried out population surveys to estimate trends in risk factors. Trends in event rates were regressed on trends in risk score and in individual risk factors. Findings Smoking rates decreased in most male populations but trends were mixed in women; mean blood pressures and cholesterol concentrations decreased, body-mass index increased, and overall risk scores and coronary-event rates decreased. The model of trends in 10-year coronary-event rates against risk scores and single risk factors showed a poor fit, but this was improved with a 4-year time lag for coronary events. The explanatory power of the analyses was limited by imprecision of the estimates and homogeneity of trends in the study populations. Interpretation Changes in the classic risk factors seem to partly explain the variation in population trends in CHD. Residual variance is attributable to difficulties in measurement and analysis, including time lag, and to factors that were not included, such as medical interventions. The results support prevention policies based on the classic risk factors but suggest potential for prevention beyond these.

Effects of a program of intervention on parental distress following infant death

A longitudinal study of 144 patents (65 fathers, 79 mothers) was conducted to evaluate the effectiveness of a program of intervention in relieving the psychological distress of parents affected by infant death. Participants were assessed in terms of their psychiatric disturbance, depression, anxiety, physical symptoms, dyadic adjustment, and coping strategies. The experimental group (n = 84) was offered an intervention program comprising the use of specially designed resources and contact with a trained grief worker. A control group (n = 60) was given routine community care. Parental reactions were assessed at four to six weeks postloss (prior to the implementation of the intervention program), at six months postloss, and at 15 months postloss. A series of multivariate analyses of valiance revealed that the intervention was effective in reducing the distress of parents, particularly those assessed prior to the intervention as being at high-risk of developing mourning difficulties. Effects of the intervention were noted in terms of parents' overall psychiatric disturbance, marital quality, and paternal coping strategies.

Colour vision in billfish

Members of the billfish family are highly visual predatory teleosts inhabiting the open ocean. Little is known about their visual abilities in detail, but past studies have indicated that these fishes were:ere likely to be monochromats. This study however, presents evidence of two anatomically distinct cone types in billfish. The cells are arranged in a regular mosaic pattern of single and twin cones as in many fishes, and this arrangement suggests that the different cone types also show different spectral sensitivity, which is the basis for colour vision. First measurements using microspectrophotometry (MSP) revealed a peak absorption of the rod pigment at 484 nm, indicating that MSP, despite technical difficulties, will be a decisive tool in proving colour vision in these offshore fishes. When hunting, billfish such as the sailfish flash bright blue bars on their sides. This colour reflects largely in ultraviolet (UV) light at 350 nm as revealed by spectrophotometric measurements. Billfish lenses block light of wavelengths below 400 nm, presumably rendering the animal blind to the UV component of its own body colour. Interestingly at least two prey species of billfish have lenses transmitting light in the UV waveband and are therefore likely to perceive a large fraction of the UV peak found in the blue bar of the sailfish. The possible biological significance of this finding is discussed.

Characteristics of DSM-IV and ICD-10 cannabis dependence among Australian adults: results from the National Survey of Mental Health and Wellbeing

A representative sample (n = 10 641) of Australian adults completed a structured diagnostic interview assessing the prevalence of mental and substance use disorders in the last year. The prevalence of DSM-IV (1.5%) and ICD-10 (1.7%) cannabis dependence was similar. DSM-IV and ICD-10 dependence criteria comprised unidimensional syndromes. The most common symptoms among dependent and non-dependent users were difficulties with controlling use and withdrawal, although there were marked differences in symptom prevalence. Dependent users reported a median of four symptoms. There was good to excellent diagnostic concordance (kappas = 0.7-0.9) between systems for dependence but not for abuse/harmful use (Y = 0.4). These findings provide some support for the validity of cannabis dependence. (C) 2001 Elsevier Science Ireland Ltd. All rights reserved.

Challenges and approaches to estimating mortality attributable to the use of selected illicit drugs

A number of unique challenges are faced when attempting to estimate mortality attributable to illicit drugs. The hidden nature of illicit drug use creates difficulties in quantifying the prevalence of such use; identifying adverse health effects associated with exposure, and calculating the risk of these effects. The use of cohort studies of drug users allows the identification of causes of mortality associated with drug use and the determination of the risk of these causes. This risk estimate can then be used in conjunction with estimates of the prevalence of drug use to, extrapolate the burden of mortality. We identify a number of such studies and present some solutions to the major challenges faced when attempting to estimate the global burden of mortality attributable to illicit drug use. Copyright (C) 2001 S. Karger AG, Basel.

Small area population disease burden

Small area health statistics has assumed increasing importance as the focus of population and public health moves to a more individualised approach of smaller area populations. Small populations and low event occurrence produce difficulties in interpretation and require appropriate statistical methods, including for age adjustment. There are also statistical questions related to multiple comparisons. Privacy and confidentiality issues include the possibility of revealing information on individuals or health care providers by fine cross-tabulations. Interpretation of small area population differences in health status requires consideration of migrant and Indigenous composition, socio-economic status and rural-urban geography before assessment of the effects of physical environmental exposure and services and interventions. Burden of disease studies produce a single measure for morbidity and mortality - disability adjusted life year (DALY) - which is the sum of the years of life lost (YLL) from premature mortality and the years lived with disability (YLD) for particular diseases (or all conditions). Calculation of YLD requires estimates of disease incidence (and complications) and duration, and weighting by severity. These procedures often mean problematic assumptions, as does future discounting and age weighting of both YLL and YLD. Evaluation of the Victorian small area population disease burden study presents important cross-disciplinary challenges as it relies heavily on synthetic approaches of demography and economics rather than on the empirical methods of epidemiology. Both empirical and synthetic methods are used to compute small area mortality and morbidity, disease burden, and then attribution to risk factors. Readers need to examine the methodology and assumptions carefully before accepting the results.