Opposing roles for medial and central amygdala in the initiation of noradrenergic cell responses to a psychological stressor

Psychological stressors trigger the activation of medullary noradrenergic cells, an effect that has been shown to depend upon yet-to-be-identified structures located higher in the brain. To test whether the amygdala is important in this regard, we examined the effects of amygdala lesions on noradrenergic cell responses to restraint, and also looked at whether any amygdala cells that respond to restraint project directly to the medulla. Ibotenic acid lesions of the medial amygdala completely abolished restraint-induced Fos expression in A1 and A2 noradrenergic cells. In contrast, lesions of the central amygdala actually facilitated noradrenergic cell responses to restraint. Tracer deposits in the dorsomedial (but not ventrolateral) medulla retrogradely labelled many cells in the central nucleus of the amygdala, but none of these cells expressed Fos in response to restraint. These data suggest for the first time that the medial amygdala is critical to the activation of medullary noradrenergic cells by a psychological stressor whereas the central nucleus exerts an opposing, inhibitory influence upon noradrenergic cell recruitment. The initiation of noradrenergic cell responses by the medial amygdala does not involve a direct projection to the medulla. Accordingly, a relay through some other structure, such as the hypothalamic paraventricular nucleus, warrants careful consideration.

Conditional performance evaluation and the relevance of money flows for Australian international equity funds

This paper assesses the importance of fund flows in the performance evaluation of Australian international equity funds. Two concepts of fund flows are considered in the context of a conditional asset pricing model. The first measure is net fund flow relative to fund size and the second is net fund flow relative to sector flows. We find that incorporating a fund flow measure relative to the sector flow results in a reduction of measured perverse market timing. The results indicate that, at the individual fund level, cash flows are relevant in assessing management outcomes.

Knowledge, economy, technology and society: The politics of discourse

The WSIS is centrally interested in knowledge and has defined for itself a mission that is broadly humanitarian. Its development ‘talk’ is, rightly, replete with notions of equity, preserving culture, justice, human rights and so on. In incorporating such issues into knowledge society and economy discussions, WSIS has adopted a different posture towards knowledge than is seen in dominant discourses. This study analyses the dominant knowledge discourse using a large corpus of knowledge-related policy documents, discourse theory and an interrelational understanding of knowledge. I show that it is important to understand this dominant knowledge discourse because of its capacity to limit thought and action in relation to its central topic, knowledge. The results of this study demonstrate that the dominant knowledge discourse is technocratic, frequently insensitive to the humane mission at the core of the WSIS, and is based on a partial understanding of what knowledge is and how knowledge systems work. Moreover, I show that knowledge is inherently political, that the dominant knowledge discourse is politically oriented towards the concerns of business and technology, but that an emancipatory politics of knowledge is possible.

The interaction of water flow and nutrients on aquatic plant growth

A long-term experiment was conducted to compare the effects of flowing and still water on growth, and the relationship between water flow and nutrients, in Aponogeton elongatus, a submerged aquatic macrophyte. A. elongatus plants were grown for 23 weeks with three levels of nutrition (0, 0.5 and 1g Osmocote Plus(R) fertiliser pot(-1)) in aquaria containing stirred or unstirred water. Fertilized plants grew much better than non-fertilized. The highest fertilizer level produced 29% wider leaves and 58% higher total dry weight in stirred water. Stirred water increased leaf area by 40% and tuber size by 81%, but only with the highest level of nutrition. These results suggest that this plant depends on its roots for mineral uptake, rather than from the open water, and the major limitation to growth in still water is the supply of dissolved inorganic carbon. It was the combined effects of nutrient availability and stirring that produced the strongest response in plant growth, morphology and composition. This study provides some explanation for the observations of others that these plants grow best in creeks or river systems with permanently flowing water.

Climate change, human impacts, and the resilience of coral reefs

The diversity, frequency, and scale of human impacts on coral reefs are increasing to the extent that reefs are threatened globally. Projected increases in carbon dioxide and temperature over the next 50 years exceed the conditions under which coral reefs have flourished over the past half-million years. However, reefs will change rather than disappear entirely, with some species already showing far greater tolerance to climate change and coral bleaching than others. International integration of management strategies that support reef resilience need to be vigorously implemented, and complemented by strong policy decisions to reduce the rate of global warming.

The contribution of research to Australian policy responses to heroin dependence 1990-2001: a personal retrospection

Periodic public concern about heroin use has been a major driver of Australian drug policy in the four decades since heroin use was first reported. The number of heroin-dependent people in Australia has increased from several hundreds in the late 1960s to around 100000 by the end of the 1990s. In this paper I do the following: (1) describe collaborative research on heroin dependence that was undertaken between 1991 and 2001 by researchers at the National Drug and Alcohol Research Centre: (2) discuss the contribution that this research may have made to the formulation of policies towards the treatment of heroin dependence during a period when the policy debate crystallized around the issue of whether or not Australia should conduct a controlled trial of heroin prescription; and (3) reflect on the relationships between research and policy-making in the addictions field, specifically on the roles of investigator-initiated and commissioned research, the interface between researchers, funders and policymakers: and the need to be realistic about the likely impact of research on policy and practice.

'Lots of little kindnesses': valuing the role of older Australians as informal volunteers in the community

This paper describes the ways in which older people contribute to their communities and families as informal volunteers. It challenges current ways of thinking that assign an economic value to the productive activities undertaken by older people. Using qualitative data from a study of older people resident in Queensland, Australia, the paper explores the ways that older people contribute to their families and to the community and the outcomes associated with these activities. Two specific themes emerged from the data: first, the ways' in which older people contribute to strong inter-generational relations, and second, how they provide essential mutual support that permits many older people to remain living in the community. These contributions, while often small in themselves, are in aggregate critical both to family functioning and to the maintenance of sustainable and healthy communities. Many are reciprocal interactions that add value to the lives of individuals and offer positive social roles in later life, and they may be particularly important for those from minority cultural backgrounds or at risk of social isolation. The findings suggest that older people are integral to community and civil society and, therefore, that social policy should respond to the ageing of Australia's population and recognise the positive contributions of older people, rather than emphasising the costs of demographic change.