Silica reduces the toxicity of aluminium to a tropical freshwater fish (Mogurnda mogurnda)

The toxicity of aluminium (Al) to fish in acidic waters has been well documented. It was therefore expected that Al toxicity would be significant in fish communities in Gadjarrigamarndah (Gadji) Creek, a seasonally flowing stream in tropical northern Australia. This creek receives acidic groundwater containing elevated concentrations of Al from earlier land irrigation of treated mine tailings water from the former Nabarlek uranium mine. It was hypothesised that Al toxicity was reduced by high levels of silica (Si) in the water, and the subsequent formation of Al-silicate complexes. This prompted a laboratory assessment of the toxicity of Gadji Creek water to sac-fry of the native fish, Mogurnda mogurnda, followed by more detailed investigation of the toxicity of Al and the influence of Si in reducing Al toxicity. No mortality of M. mogurnda sac-fry was observed in two toxicity tests using Gadji Creek water collected in August 1997 and September 1998. The majority of Al (80-95%) was calculated to be complexed with humic substances and sulfate, with <1% being complexed with silicate. Assessment of the influence of silica on the acute toxicity of Al in the absence of natural organic complexants (i.e. in reconstituted freshwater, pH 5) revealed that Si reduced Al toxicity. As the molar ratio of Si:Al was increased, the percent survival of M. mogurnda sac-fry increased until there was no significant (P > 0.05) difference from the controls. However, speciation modelling again predicted that little (<3%) Al complexed with silicate, with the speciation and bioavailability of Al remaining constant as the molar ratio of Si:Al increased. Therefore, the original hypothesis that Al-silicate complexes in solution reduced the toxicity of Al to M. mogurnda could not be supported. This potential mechanism, and an alternative hypothesis, that Si competes with Al for binding sites at the fish gill surface, requires further investigation. Crown Copyright (C) 2002 Published by Elsevier Science Ltd. All rights reserved.

Scaling of decoherence effects in quantum computers

The scaling of decoherence rates with qubit number N is studied for a simple model of a quantum computer in the situation where N is large. The two state qubits are localized around well-separated positions via trapping potentials and vibrational centre of mass motion of the qubits occurs. Coherent one and two qubit gating processes are controlled by external classical fields and facilitated by a cavity mode ancilla. Decoherence due to qubit coupling to a bath of spontaneous modes, cavity decay modes and to the vibrational modes is treated. A non-Markovian treatment of the short time behaviour of the fidelity is presented, and expressions for the characteristic decoherence time scales obtained for the case where the qubit/cavity mode ancilla is in a pure state and the baths are in thermal states. Specific results are given for the case where the cavity mode is in the vacuum state and gating processes are absent and the qubits are in (a) the Hadamard state (b) the GHZ state.

Moderating effect of allocentrism on the pay referent comparison-pay level satisfaction relationship

Pay referent comparisons (comparisons of one's salary to that of others) such as other-inside (salary of other people in the organisation), other-outside (the market rate), and cost-of- living, have been shown to influence pay level satisfaction. Bordia and Blau (1998) identified family as another referent that had a significant effect on pay level satisfaction in a sample of public and private sector employees in India. The finding was interpreted in view of the importance of family in collectivistic cultures. In the study reported here, the moderating influence of an individual differences variable, allocentrism-idiocentrism (the individual level conceptualisation of collectivism-individualism) on pay referent comparison-pay level satisfaction relationship was investigated. A sample of 146 employees from three public sector organisations in India participated in the study. In line with the predictions, results showed that after controlling for age, tenure, and pay level, pay referent comparisons explained more variance in pay level satisfaction for allocentrics than for idiocentrics. Family and pay level were stronger explanatory variables of pay level satisfaction for allocentrics and idiocentrics, respectively, while cost of living was a significant explanatory variable for both sub-groups.

Quantum transport and integrability of the Anderson model for a quantum dot with multiple leads

We show that an Anderson Hamiltonian describing a quantum dot connected to multiple leads is integrable. A general expression for the nonlinear conductance is obtained by combining the Bethe ansatz exact solution with Landauer-Buttiker theory. In the Kondo regime, a closed form expression is given for the matrix conductance at zero temperature and when all the leads are close to the symmetric point. A bias-induced splitting of the Kondo resonance is possible for three or more leads. Specifically, for N leads, with each at a different chemical potential, there can be N-1 Kondo peaks in the conductance.

Punctuated equilibrium and linear progression: Toward a new understanding of group development

This study proposes gaining a new understanding of group development by considering the integrative and the punctuated equilibrium models of group development as complementary rather than competing. We hypothesized that we would observe both punctuated equilibrium and linear progression in content-analyzed data from 25 simulated project teams, albeit on different dimensions. We predicted changes in time awareness and in task and pacing activity in line with the punctuated equilibrium model and changes in structure and process on task and socioemotional dimensions in line with the integrative model. Results partially supported predictions for both models.

Electrochemical deposition of cupric ions for the determination of mass transfer rates to a stepped rotating cylinder electrode

The stepped rotating cylinder electrode (SRCE) geometry has been developed as a simple aid to the practical study of the flow-enhanced corrosion and applied electrochemistry problems commonly observed under conditions of disturbed, turbulent flow. The electrodeposition of cupric ions from an acid sulphate plating bath has been used to characterise differential rates of mass transfer to the SRCE. The variation in thickness of electrodeposited copperfilms has allowed the mapping of local rates of mass transfer over the active surface of this geometry. Both optical and scanning electron microscopy were used for the examination of metallographic sections to provide a high resolution evaluation of the distribution of mass transfer coefficient. Results are also discussed using the convective-diffusion model in combination with the existing direct numerical flow simulation (DNS) data for this geometry.

Improving family functioning and child outcome in methadone maintained families: the Parents Under Pressure programme

Twelve families responded to posters displayed in a methadone clinic for inclusion in a pilot study assessing the viability and potential utility of an intensive, multi-component family-focused intervention, the Parents Under Pressure programme. The programme was designed to improve child behaviour, decrease parental stress and improve family functioning in methadone-maintained families by targeting affect regulation, mood, views of self as a parent, drug use and parenting skills. Nine of the families completed the programme delivered in their homes; eight were recontacted at 3 months. Each family reported significant improvements in three domains: parental functioning, parent - child relationship and parental substance use and risk behaviour. In addition to the changes in family functioning, the majority of families reported a decrease in concurrent alcohol use, HIV risk-taking behaviour and maintenance dose of methadone. The families reported high levels of satisfaction with the programme. It is recommended that future studies include independent measures (e.g. behavioural observations) of child outcome and parental functioning. The results were optimistic and provided the impetus to evaluate the treatment programme using a randomized controlled trial.

Young refugees talk about well-being: A qualitative analysis of refugee youth mental health from three states

Young people from refugee backgrounds face enormous challenges in the settlement process within Australia. They must locate themselves within a new social, cultural, geographic and adult space, yet also try to find security within the spaces of their own families and ethnic communities. Traumas of the past can mix with painful experiences of the present. The stressors in the lives of these young people can be both complex and diverse. This paper explores the nature a/these stressors among young people from refugee backgrounds living in Australia. [t is based On in-depth interviews with 76 young people from refugee backgrounds now living in Brisbane, Adelaide and Perth. A qualitative analysis of the impact of these stressors as well as the coping strategies employed are discussed It is argued that trauma exists

Earnings management in response to the introduction of the Australian gold tax

Earnings from gold mining in Australia remained tax-exempt for almost seven decades until January 1, 1991. In the early 1980s, rapid economic prosperity induced by escalated gold prices brought the Australian gold-mining industry under intense political scrutiny. Using a variant of the modified Jones model, this paper provides evidence of significant downward earnings management by Australian gold-mining firms, which is consistent with their attempts to mitigate political costs during the period from June 1985 to May 1988. In contrast, test of earnings management over a similar period in a control sample of Canadian gold-mining firms produced insignificant results. Further, empirical results are robust to several sensitivity tests performed. During the period from June 1988 to December 1990, the Australian firms were found to have engaged in economic earnings management. This is consistent with the sample firms' incentive of maximizing economic earnings immediately prior to the introduction of income tax on gold mining. The findings of this study help to understand the impact of earnings management on the efficient resource allocation in an economy. They also contribute toward understanding the linkage between regulation of accounting for special purposes and general-purpose financial. reporting.

How young people from culturally and linguistically diverse backgrounds experience mental health: Some insights for mental health nurses

This article reports on part of a study that looked at the mental health of culturally and linguistically diverse (CALD) young people. The research sought to learn from CALD young people, carers, and service providers experiences relevant to the mental health of this group of young people. The ultimate goal was to gain insights that would inform government policy, service providers, ethnic communities and most importantly the young people themselves. To this end, qualitative interviews were undertaken with 123 CALD young people, 41 carers and 14 mental health service providers in Queensland, Western Australia and South Australia. Only one aspect of the study will be dealt with here, namely the views of the young CALD participants, which included risk factors, coping strategies and recommendations about how they could be supported in their struggle to maintain mental health. One of the most important findings of the study relates to the resilience of these young people and an insight into the strategies that they used to cope. The efforts of these young people to assist us in our attempts to understand their situation deserve to be rewarded by improvements in the care that we provide. To this end this article sets out to inform mental health nurses of the results of the study so that they will be in a position to better understand the needs and strengths of their CALD clients and be in a better position to work effectively with them.

Dragging down and dragging up: How relative group status affects responses to common fate

The authors examined whether status differences moderate the effects of common fate on subgroup relations. University students (N = 103) were led to believe that their subgroup was performing well (high status) or poorly (low status) relative to another subgroup. They were then told that the combined performances of the subgroups would have shared implications for their subgroup's welfare. (common fate) or that there would be a direct link between their subgroup's performance and its welfare (no common fate). High-status (but not low-status) group members responded to the common fate situation by (a) decategorizing and (b) showing benevolence to the out-group. Results are discussed with respect to their implications for managing subgroup relations.

Not being what you claim to be: impostors as sources of group threat

We examine the notion of impostors within groups, defined in this paper as people who make public claims to an identity while disguising their failure to fulfil key criteria for group membership. In Experiment 1, vegetarians showed heightened levels of negative affect toward vegetarians who ate meat occasionally compared to an authentic vegetarian. In contrast, non-vegetarians saw the impostor to be marginally more likeable than the authentic vegetarian. In Experiments 2 and 3, participants evaluated only a vegetarian who ate meat. Evaluations of the target were influenced by group attachment, such that participants who identified strongly as vegetarians downgraded the target more strongly and experienced more negative affect than did moderate identifiers and non-vegetarians. Participants were also sensitive to the size of the gulf between the target's claims for identity and their behaviour. Thus, targets who made public claims to being a vegetarian but ate meat were evaluated more negatively than were people who kept their claims for identity private (Experiment 2). Similarly, targets who tried to keep their deviant behaviour secret were evaluated more negatively than were people who openly admitted their deviant behaviour (Experiment 3). The reasons why impostors might threaten the integrity of group identities are discussed. Copyright (C) 2003 John Wiley Sons, Ltd.