Extrinsic versus intrinsic factors in the decline and extinction of Australian marsupials

Recent attempts to explain the susceptibility of vertebrates to declines worldwide have largely focused on intrinsic factors such as body size, reproductive potential, ecological specialization, geographical range and phylogenetic longevity. Here, we use a database of 145 Australian marsupial species to test the effects of both intrinsic and extrinsic factors in a multivariate comparative approach. We model five intrinsic (body size, habitat specialization, diet, reproductive rate and range size) and four extrinsic (climate and range overlap with introduced foxes, sheep and rabbits) factors. We use quantitative measures of geographical range contraction as indices of decline. We also develop a new modelling approach of phylogenetically independent contrasts combined with imputation of missing values to deal simultaneously with phylogenetic structuring and missing data. One extrinsic variable-geographical range overlap with sheep-was the only consistent predictor of declines. Habitat specialization was independently but less consistently associated with declines. This suggests that extrinsic factors largely determine interspecific variation in extinction risk among Australian marsupials, and that the intrinsic factors that are consistently associated with extinction risk in other vertebrates are less important in this group. We conclude that recent anthropogenic changes have been profound enough to affect species on a continent-wide scale, regardless of their intrinsic biology.

Simultaneous X-ray imaging of plant root growth and water uptake in thin-slab systems

Direct and simultaneous observation of root growth and plant water uptake is difficult because soils are opaque. X-ray imaging techniques such as projection radiography or Computer Tomography (CT) offer a partial alternative to such limitations. Nevertheless, there is a trade-off between resolution, large field-of-view and 3-dimensionality: With the current state of the technology, it is possible to have any two. In this study, we used X-ray transmission through thin-slab systems to monitor transient saturation fields that develop around roots as plants grow. Although restricted to 2-dimensions, this approach offers a large field-of-view together with high spatial and dynamic resolutions. To illustrate the potential of this technology, we grew peas in 1 cm thick containers filled with soil and imaged them at regular intervals. The dynamics of both the root growth and the water content field that developed around the roots could be conveniently monitored. Compared to other techniques such as X-ray CT, our system is relatively inexpensive and easy to implement. It can potentially be applied to study many agronomic problems, such as issues related to the impact of soil constraints (physical, chemical or biological) on root development.

Screening for leprosy in immigrants: A decision analysis model

Almost all leprosy cases reported in industrialized countries occur amongst immigrants or refugees from developing countries where leprosy continues to be an important health issue. Screening for leprosy is an important question for governments in countries with immigration and refugee programmes. A decision analysis framework is used to evaluate leprosy screening. The analysis uses a set of criteria and parameters regarding leprosy screening, and available data to estimate the number of cases which would be detected by a leprosy screening programme of immigrants from countries with different leprosy prevalences, compared with a policy of waiting for immigrants who develop symptomatic clinical diseases to present for health care. In a cohort of 100,000 immigrants from high leprosy prevalence regions (3.6/10,000), screening would detect 32 of the 42 cases which would arise in the destination country over the 14 years after migration; from medium prevalence areas (0.7/10,000) 6.3 of the total 8.1 cases would be detected, and from low prevalence regions (0.2/10,600) 1.8 of 2.3 cases. Using Australian data, the migrant mix would produce 74 leprosy cases from 10 years intake; screening would detect 54, and 19 would be diagnosed subsequently after migration. Screening would only produce significant case-yield amongst immigrants from regions or social groups with high leprosy prevalence. Since the number of immigrants to Australia from countries of higher endemnicity is not large routine leprosy screening would have a small impact on case incidence.

Organisational Factors Contributing to Violations by Rural and Remote Area Nurses during Medication Administration

Medication errors are a leading cause of unintended harm to patients in Australia and internationally. Research in this area has paid relatively little attention to the interactions between organisational factors and violations of procedures in producing errors, although violations have been found to increase the likelihood of these errors. This study investigated the role of organisational factors in contributing to violations by nurses when administering medications. Data were collected using a self-report questionnaire completed by 506 nurses working in either rural or remote areas in Queensland, Australia. This instrument was used to develop a path model wherein organisational variables predicted 21% of the variance in self-reported violations. Expectations of medical officers mediated the relationship between working conditions of nursing staff and violation behaviour.

Patents and the CGIAR system of International Agricultural Research Centres' germplasm collections under the International Treaty on Plant Genetic Resources for Food and Agriculture

A key controversy in negotiating the International Treaty on Plant Genetic Resources for Food and Agriculture, and the likely long-term effectiveness of the agreement, is the way in which the intellectual property provisions are interpreted and applied to the key genetic resources forming the Consultative Group on International Agricultural Research (CGIAR) system of International Agricultural Research Centres' (IARC) collections. This paper reviews the intellectual property provisions in the treaty and examines the likely consequences from patenting under the Patents Act 1990 over materials derived from these collections. The consequence is argued to be significant and, over time, these practices are likely to deplete the usefulness of these collections and undermine the relevance of the treaty. The paper concludes that Australia's interests might best be served by arguing that access to these collections, and the other materials under the treaty, be subject to a non-exclusive, royalty free licence for any use of the derived materials to develop useful new plant varieties.

Participatory assessment of rural livelihoods in the Central Highlands of Vietnam

There is a need for improved monitoring and evaluation (M&E) of participatory research with smallholder farmers, in particular to help differentiate between different types of farm household with different needs. This paper reports some of the results of a study to develop participatory M&E tools for the Forages for Smallholders Project in Southeast Asia, focusing on an upland commune in central Vietnam with a highly diverse crop-livestock system. Participatory rural appraisal techniques were used within a rural livelihoods framework to assess the differing livelihoods of poor, average, and better-off households. There were found to be marked differences between households, particularly in human resources, landholdings, and cattle numbers, affecting the livelihood strategies pursued. The improved understanding of livelihood strategies was gained in a cost-effective way and could be readily used by project participants to monitor the impacts of the introduced forages within the commune, enabling better focusing of the participatory research process on the needs and circumstances of poor farmers. (C) 2003 Elsevier Ltd. All rights reserved.

ICRAM (the International Campaign to Revitalise Academic Medicine): Agenda setting

Following die launch by the BMJ and others of the campaign to promote academic medicine, a working party of 20 medical academics from all over the world was convened to develop a plan of action.

Cited2 is required both for heart morphogenesis and establishment of the left-right axis in mouse development

Establishment of the left-right axis is a fundamental process of vertebrate embryogenesis. Failure to develop left-right asymmetry leads to incorrect positioning and morphogenesis of numerous internal organs, and is proposed to underlie the etiology of several common cardiac malformations. The transcriptional modulator Cited2 is essential for embryonic development: Cited2-null embryos die during gestation with profound developmental abnormalities, including cardiac malformations, exencephaly and adrenal agenesis. Cited2 is also required for normal establishment of the left-right axis; we demonstrate that abnormal heart looping and right atrial and pulmonary isomerism are consistent features of the left-right-patterning defect. We show by gene expression analysis that Cited2 acts upstream of Nodal, Lefty2 and Pitx2 in the lateral mesoderm, and of Lefty1 in the presumptive floor plate. Although abnormal left-right patterning has a major impact on the cardiac phenotype in Cited2-null embryos, laterality defects are only observed in a proportion of these embryos. We have therefore used a combination of high-resolution imaging and three-dimensional (3D) modeling to systematically document the full spectrum of Cited2-associated cardiac defects. Previous studies have focused on the role of Cited2 in cardiac neural crest cell development, as Cited2 can bind the transcription factor Tfap2, and thus affect the expression of Erbb3 in neural crest cells. However, we have identified Cited2-associated cardiac defects that cannot be explained by laterality or neural crest abnormalities. In particular, muscular ventricular septal defects and reduced cell density in the atrioventricular (AV) endocardial cushions are evident in Cited2-null embryos. As we found that Cited2 expression tightly correlated with these sites, we believe that Cited2 plays a direct role in development of the AV canal and cardiac septa. We therefore propose that, in addition to the previously described reduction of cardiac neural crest cells, two other distinct mechanisms contribute to the spectrum of complex cardiac defects in Cited2-null mice; disruption of normal left-right patterning and direct loss of Cited2 expression in cardiac tissues.

Two-dimensional approximation for tidal dynamics in coastal aquifers: Capillarity correction

Most previous investigations on tide-induced watertable fluctuations in coastal aquifers have been based on one-dimensional models that describe the processes in the cross-shore direction alone, assuming negligible along-shore variability. A recent study proposed a two-dimensional approximation for tide-induced watertable fluctuations that took into account coastline variations. Here, we further develop this approximation in two ways, by extending the approximation to second order and by taking into account capillary effects. Our results demonstrate that both effects can markedly influence watertable fluctuations. In particular, with the first-order approximation, the local damping rate of the tidal signal could be subject to sizable errors.

Quantum analysis of the nondegenerate optical parametric oscillator with injected signal

In this paper we study the nondegenerate optical parametric oscillator with injected signal, both analytically and numerically. We develop a perturbation approach which allows us to find approximate analytical solutions, starting from the full equations of motion in the positive-P representation. We demonstrate the regimes of validity of our approximations via comparison with the full stochastic results. We find that, with reasonably low levels of injected signal, the system allows for demonstrations of quantum entanglement and the Einstein-Podolsky-Rosen paradox. In contrast to the normal optical parametric oscillator operating below threshold, these features are demonstrated with relatively intense fields.

Globalizing policy sociology in education: Working with Bourdieu

This paper uses Bourdieu to develop theorizing about policy processes in education and to extend the policy cycle approach in a time of globalization. Use is made of Bourdieu's concept of social field and the argument is sustained that in the context of globalization the field of educational policy has reduced autonomy, with enhanced cross-field effects in educational policy production, particularly from the fields of the economy and journalism. Given the social rather than geographical character of Bourdieu's concept of social fields, it is also argued that the concept can be, and indeed has to be, stretched beyond the nation to take account of the emergent global policy field in education. Utilizing Bourdieu's late work on the globalization of the economy through neo-liberal politics, we argue that a non-reified account of the emergent global educational policy field can be provided.

An evaluation of the evidence for linkages between mangroves and fisheries: A synthesis of the literature and identification of research directions

There is a widely held paradigm that mangroves are critical for sustaining production in coastal fisheries through their role as important nursery areas for fisheries species. This paradigm frequently forms the basis for important management decisions on habitat conservation and restoration of mangroves and other coastal wetlands. This paper reviews the current status of the paradigm and synthesises the information on the processes underlying these potential links. In the past, the paradigm has been supported by studies identifying correlations between the areal and linear extent of mangroves and fisheries catch. This paper goes beyond the correlative approach to develop a new framework on which future evaluations can be based. First, the review identifies what type of marine animals are using mangroves and at what life stages. These species can be categorised as estuarine residents, marine-estuarine species and marine stragglers. The marine-estuarine category includes many commercial species that use mangrove habitats as nurseries. The second stage is to determine why these species are using mangroves as nurseries. The three main proposals are that mangroves provide a refuge from predators, high levels of nutrients and shelter from physical disturbances. The recognition of the important attributes of mangrove nurseries then allows an evaluation of how changes in mangroves will affect the associated fauna. Surprisingly few studies have addressed this question. Consequently, it is difficult to predict how changes in any of these mangrove attributes would affect the faunal communities within them and, ultimately, influence the fisheries associated with them. From the information available, it seems likely that reductions in mangrove habitat complexity would reduce the biodiversity and abundance of the associated fauna, and these changes have the potential to cause cascading effects at higher trophic levels with possible consequences for fisheries. Finally, there is a discussion of the data that are currently available on mangrove distribution and fisheries catch, the limitations of these data and how best to use the data to understand mangrove-fisheries links and, ultimately, to optimise habitat and fisheries management. Examples are drawn from two relatively data-rich regions, Moreton Bay (Australia) and Western Peninsular Malaysia, to illustrate the data needs and research requirements for investigating the mangrove-fisheries paradigm. Having reliable and accurate data at appropriate spatial and temporal scales is crucial for mangrove-fisheries investigations. Recommendations are made for improvements to data collection methods that would meet these important criteria. This review provides a framework on which to base future investigations of mangrove-fisheries links, based on an understanding of the underlying processes and the need for rigorous data collection. Without this information, the understanding of the relationship between mangroves and fisheries will remain limited. Future investigations of mangrove-fisheries links must take this into account in order to have a good ecological basis and to provide better information and understanding to both fisheries and conservation managers.

Transgenic expression of a viral oncoprotein exclusively in K14(+) epithelial cells results in peripheral but not central CD8 T cell tolerance

The role of thymic versus peripheral epithelial cells in the negative selection of the peptide-specific CD8 T cell repertoire is still largely unresolved. We have generated TCRb chain transgenic mice in which 20–35% of peripheral CD8 T cells recognize an epitope from a viral, nuclear oncoprotein (human papillomavirus type 16 E7) in the context ofMHC class I, H-2Db. When T cells from these transgenic mice develop through the thymus of a second transgenic mouse expressing E7 from a keratin 14 promoter, no major perturbation to thymic T cell development is observed over a 7 month period. In contrast, peripheral CD8 T cell responses in these same mice (E7TCRxK14E7 double transgenic) become reduced over time. This data suggests that peripheral tolerance mechanisms predominate over thymic negative selection in controlling CD8 T cell responses to this epithelial, nuclear oncoprotein.

Defective NF-kappaB Activation in Response to LPS in Type 1 Diabetes Dendritic Cells

Dendritic cells (DC) are the potent antigen presenting cells which modulate T cell responses to self or non-self antigens. DC play a significant role in the pathogenesis of autoimmune diseases, inflammation and infection, but also in the maintenance of tolerance. NF-kappaB, particularly RelB is a crucial pathway for myeloid DC differentiation and functional maturation. While the current paradigm is that mature, nuclear RelB+ DC prime T cells for immunity/autoimmunity and immature DC for tolerance, RelB-deficient mice paradoxically develop generalised systemic autoimmune inflammatory disease with myelopoiesis and splenomegaly. Previous studies suggested abnormal DC differentiation in healthy relatives of type 1 diabetes (t1dm) patients. Therefore, we compared NF- kB activation in monocyte-derived DC from t1dm and non-t1dm controls in response to LPS. While resting DC appeared normal, DC from 6 out of 7 t1dm patients but no t2dm or rheumatoid arthritis patients failed to translocate NF- kB subunits to the nucleus in response to LPS, along with a failure to up-regulate expression of cell surface CD40 and MHC class I. NF- kB subunit mRNA increased normally in t1dm DC after LPS. Both the classical or non-canonical NF- kB pathways were affected as both TNF-a and CD40 stimulation led to a similarly abnormal NF- kB response. In contrast, expression of phosphorylated p38 MAPK and pro-inflammatory cytokine production was intact. These abnormalities in NF- kB activation appear to be generally and specifically applicable at a post-translational level in t1dm, and have the capacity to profoundly influence immunoregulation in affected individuals.

"Futuristic medical education"

The Australian National Medical Education Colloquium provided a productive forum for medical educators to meet and to discuss and debate important contemporary issues affecting Australian medical schools. None of us know what the future will hold, and some of the possibilities discussed at the Colloquium were futuristic indeed. We would be wise to keep an open mind, to focus very much on competence and fitness to practice, and to develop a strong evidence base, as we travel this important path.