Groups, graphs and mutually unbiased bases

A new characteristic free approach to constructing large sets of mutually unbiased bases in Hilbert space is developed. We associate with a seed set of bases a finite subgroup of which defines a strongly regular graph. Large sets of mutually unbiased bases are obtained as the cliques of the graph.

"I will start treatment when I think the time is right":HIV-positive gay men talk about their decision not to access antiretroviral therapy.

In a qualitative study, 20 HIV-infected Australian gay men were interviewed about their decision not to access antiretroviral drug therapy. The main reasons given for the decision were fear of side effects; fear of long-term damage to body organs; the inconvenience of the treatment regimens; belief that the regimen's demands would be a threat to morale; and belief that there was no reason to start therapy in the absence of AIDS-related symptoms. Actions taken by the men to monitor and maintain their health included seeing a doctor regularly; having regular T-cell and viral load tests; and trying to maintain a positive outlook by not letting HIV/AIDS 'take over' their lives. Almost half the men considered they had been subjected to unreasonable pressure to access therapy and there was considerable pride at having resisted this pressure. The findings suggest that the men disagreed with the biomedical model for managing HIV/AIDS only on the question of if and when to access therapy. They also suggest that underlying the men's dissent from the biomedical model was a different mode of thinking than is required by the model: while the model demands thinking that is abstract, the men focused strongly on factors close to the 'here and now' of immediate experience. The practical implications of the findings are explored.

Clock synchronization state graphs based on clock precision difference

Consistent and stable global states of clock synchronization are very important in distributed and parallel systems. This paper presents an innovative strategy and method to obtain stable global clock synchronization state graphs in asynchronous Internet environments. Our model will introduce the concept of clock precision difference as a means to evaluate running states of all clocks in this system and make this system  self-adaptive well. Finally, we introduce the concept of clock precision difference into global states analysis of clock synchronization and construct clock synchronization state graphs in order to evaluate distributed clock synchronization states. We also present detailed simulations of the strategy and mathematical analysis used on real Internet environments.

Modelling regular and estimable inverse demand systems : a distance function approach

To be useful for policy simulation in the current climate of rapid structural change, inverse demand systems must remain regular over substanstial variations in quantities. The distance function is a convenient vehicle for generating such systems. It also allows convenient imposition of prior ideas about the structure of preferences required for realistic policy work. While the distance function directly yields Hicksian inverse demand functions via the Shepard-Hanoch lemma, they are usually explicit in the unobservable level of utility (u), but lack a closed-form representation in terms of the observable variables. Note however that the unobservability of u need not hinder estimation. A simple one-dimensional numerical inversion allows the estimation of the distance function via the parameters of the implied Marshallian inverse demand functions. This paper develops the formal theory for using distance functions in this context, and reports on initial trials on the operational feasibility of the method.

The influence of leisure preference, life priority and making time on regular participation in leisure time physical activity

Using an attitude-behaviour theory approach this study examined the direct and indirect influence of preference, life priority and time allocation on regular participation in leisure-time physical activity (LTPA). The crosssectional study used self-report questionnaires to collect data from a random sample of 250 people aged 19 to 87 years living in an Australian city. The findings suggest that people’s regular participation in LTPA is not directly influenced by their preference for it. Rather, making LTPA a high life priority and allocating time for LTPA are intervening factors that explain the relationship. The outcomes emphasise the importance of encouraging the formation of a preference for physical activity in young children. They suggest all levels of government and the leisure profession emphasise work/life balance by prioritising LTPA, educating people about time management and helping them to develop time management skills.

Intersection and partition graphs

This thesis reviews previous work done on both general partition graphs and existential partition graphs, which are a generalised form of general partition graphs, and extends some of the results.

Regular exercise participation mediates the affective response to acute bouts of vigorous exercise

Physical inactivity is a leading factor associated with cardiovascular disease and a major contributor to the global burden of disease in developed countries. Subjective mood states associated with acute exercise are likely to influence future exercise adherence and warrant further investigation. The present study examined the effects of a single bout of vigorous exercise on mood and anxiety between individuals with substantially different exercise participation histories. Mood and anxiety were assessed one day before an exercise test (baseline), 5 minutes before (pre-test) and again 10 and 25 minutes post-exercise. Participants were 31 university students (16 males, 15 females; Age M = 20), with 16 participants reporting a history of regular exercise with the remaining 15 reporting to not exercise regularly. Each participant completed an incremental exercise test on a Monark cycle ergometer to volitional exhaustion. Regular exercisers reported significant post-exercise improvements in mood and reductions in state anxiety. By contrast, non-regular exercisers reported an initial decline in post-exercise mood and increased anxiety, followed by an improvement in mood and reduction in anxiety back to pre-exercise levels. Our findings suggest that previous exercise participation mediates affective responses to acute bouts of vigorous exercise. We suggest that to maximise positive mood changes following exercise, practitioners should carefully consider the individual's exercise participation history before prescribing new regimes.

Contextualising psychological distress among regular ecstasy users : the importance of sociodemographic factors and patterns of drug use

Introduction and Aims. Considerable concern has been raised about associations between ecstasy use and mental health. Studies of ecstasy users typically investigate varying levels of lifetime use of ecstasy, and often fail to account for other drug use and sociodemographic characteristics of participants, which may explain mixed findings. The current study aimed to examine the relationship between patterns of recent (last six months) ecstasy use and psychological distress among current, regular ecstasy users, controlling for sociodemographic risk factors and patterns of other drug use.

Design and Methods. Data were collected from regular ecstasy users (n = 752) recruited from each capital city in Australia as part of the Ecstasy and related Drugs Reporting System (EDRS). Psychological distress was assessed using the Kessler Psychological Distress Scale (K10). Data were analysed using multinomial logistic regression.

Results. Seven per cent of the sample scored in the ‘high’ distress category and 55% in the ‘medium’ distress category. Patterns of ecstasy use were not independently associated with psychological distress. The strongest predictors of distress were female sex, lower education, unemployment, ‘binge’ drug use including ecstasy (use for >48 h without sleep), frequent cannabis use and daily tobacco use.

Discussion and Conclusions. Regular ecstasy users have elevated levels of psychological distress compared with the general population; however, ecstasy use per se was not independently related to such distress. Other factors, including sociodemographic characteristics and other drug use patterns, appear to be more important. These findings highlight the importance of targeting patterns of polydrug use in order to reduce drug-related harm among regular ecstasy users