Set-valued Markov chains and negative semitrajectories of discretized dynamical systems

Computer simulation of dynamical systems involves a phase space which is the finite set of machine arithmetic. Rounding state values of the continuous system to this grid yields a spatially discrete dynamical system, often with different dynamical behaviour. Discretization of an invertible smooth system gives a system with set-valued negative semitrajectories. As the grid is refined, asymptotic behaviour of the semitrajectories follows probabilistic laws which correspond to a set-valued Markov chain, whose transition probabilities can be explicitly calculated. The results are illustrated for two-dimensional dynamical systems obtained by discretization of fractional linear transformations of the unit disc in the complex plane.

The role of affect and affective congruence in perceptions of leaders: an experimental study

Based on the idea that emotional exchanges determine symbolic meanings in interpersonal exchanges, we hypothesized that displays of positive and congruent affect determine members' ratings of leaders in a simulated performance appraisal context. To test the hypotheses, 537 participants viewed videotapes of four male and female leaders giving positive and negative feedback, and with facial expressions of affect that were either congruent or incongruent with the verbal message that they were delivering. Results supported hypotheses that positive and message-congruent leader affect results in more positive member ratings of the leader, assessed using a seven-item measure of members' perceptions of the leader's negotiating latitude. The least positive ratings of negotiating latitude were given when positive feedback was delivered with negative facial affect. (C) 2002 Elsevier Science Inc. All rights reserved.

Negative ion electrospray mass spectra of caerulein peptides: an aid to structural determination

MS/MS data derived from the [M-H](-) ions of desulfated caerulein peptides provide (i) sequencing information from a combination of alpha, beta and gamma backbone cleavages, and (ii) identification of specific amino acid side chains by side-chain cleavages [e.g. Ser (-CH2O), Thr (-CH3CHO) and Asp (-H2O)] (fragmentations having no counterparts in positive ion spectra). In addition, delta and/or gamma backbone cleavage ions from Asp residues identify the position of these residues in the peptide. In contrast, neither delta nor gamma cleavage ions are observed from either the Gln2 residue nor from Phe residues. Full structural information can be obtained from a consideration of the positive and negative ion MS/MS data in concert. Copyright (C) 2002 John Wiley Sons, Ltd.

Genetic and environmental risk factors and their interactions for Parkinson's disease in a Chinese population

The interaction between genetic and environmental factors for PD was examined in a Chinese population. It was found that although the intron 2 MAOB (GT)(n) repeat polymorphism was not associated with PID in the population, a relationship might have been masked by the protective effect of tea drinking. In individuals who did not drink tea (<1 cup/day), the possession of short length less than or equal to 178 bp (GT), alleles conferred a borderline significant increased risk for PD (adjusted OR = 1.47; C.l. = 1.03-2. 1). As the extent of tea consumption increased, the association between the less than or equal to178 bp allele and PD disappeared. This result suggests that the MAOB gene may be associated with PD in Chinese if the putative protective effect of tea drinking is taken into account. The significance of this finding is unclear as the study may be limited because of its marginal significance and limited numbers. However, it does demonstrate the importance of considering putative positive and negative environmental risk factors in any examination of genetic risk factors for PD. (C) 2003 Elsevier Science Ltd. All rights reserved.

International images and mass media: The effects of media coverage on Canadians' perceptions of ethnic and race relations in Australia

Recently, there has been much speculation about the impact of international media coverage of Australia's position on Indigenous people, migrants and asylum seekers on other nations' images of Australia. In this experiment we examined whether there was any basis for such concerns by considering the short-term impact of negative TV coverage of Australians on Canadian viewers. A questionnaire provided baseline data on Canadian students' perceptions of Australians and Australian race relations. Four months later, the students were assigned to one of three conditions that varied media contact with Australians. Students viewed one of two television programs (about right-wing political independent, Pauline Hanson, and her emotive criticisms of Aborigines and Asian immigrants or about an ethnically-mixed group of young Australians and their positive sense of cultural identity), or they viewed no program (no contact control). Results indicated that both positive and negative media coverage of Australians affected Canadians' views of Australia in the short-term. In particular, negative coverage (of Hanson) promoted less favourable views of Australians and Australian race relations over time and relative to the positive media and no media control conditions. The media's role in shaping international images is discussed.

Comparison of rural and urban attitudes to the conservation of Asian elephants in Sri Lanka: empirical evidence

There has been little study of economic and general attitudes towards the conservation of the Asian elephant. This paper reports and analyses results from surveys conducted in Sri Lanka of attitudes of urban dwellers and farmers towards nature conservation in general and the elephant conservation in particular. The analyses are based on urban and a rural sample. Contingent valuation techniques are used as survey instruments. Multivariate logit regression analysis is used to analyse the respondents' attitudes towards conservation of elephants. It is found that, although some variations occurred between the samples, the majority of the respondents (both rural and urban) have positive attitudes towards nature conservation in general. However, marked differences in attitudes toward elephant conservation are evident between these two samples: the majority of urban respondents were in favour of elephant conservation; rural respondents expressed a mixture of positive and negative attitudes. Overall, considerable unrecorded and as yet unutilised economic support for conservation of wild elephants exists in Sri Lanka. (C) 2002 Elsevier Science Ltd. All rights reserved.

Epstein-Barr virus-mediated protection against etoposide-induced apoptosis in BJA-B B cell lymphoma cells: role of Bcl-2 and caspase proteins

Epstein-Barr virus (EBV)-infected B cell lymphomas are resistant to apoptosis during cancer development and treatment with therapies. The molecular controls that determine why EBV infection causes apoptosis resistance need further definition. EBV-positive and EBV-negative BJA-B B cell lymphoma cell lines were used to compare the expression of selected apoptosis-regulating Bcl-2 and caspase proteins in EBV-related apoptosis resistance, after 8 hr or 18-24 hr etoposide treatment (80 muM). Apoptosis was quantified using morphology and verified with Hoechst 33258 nuclear stain and electron microscopy. Fluorescence activated cell sorting (FACS) was used to analyse effects on cell cycle of the EBV infection as well as etoposide treatment. Anti-apoptotic Bcl-2 and Bcl-XL, pro-apoptotic Bax, caspase-3 and caspase-9 expression and activation were analysed using Western immunoblots and densitometry. EBV-positive cultures had significantly lower levels of apoptosis in untreated and etoposide-treated cultures in comparison with EBV-negative cultures (p < 0.05). FACS analysis indicated a strong G2/M block in both cell sublines after etoposide treatment. Endogenous Bcl-2 was minimal in the EBV-negative cells in comparison with strong expression in EBV-positive cells. These levels did not alter with etoposide treatment. Bcl-XL was expressed endogenously in both cell lines and had reduced expression in EBV-negative cells after etoposide treatment. Bax showed no etoposide-induced alterations in expression. Pro-caspase-9 and -3 were seen in both EBV-positive and -negative cells. Etoposide induced cleavage of caspase-9 in both cell lines, with the EBV-positive cells having proportionally less cleavage product, in agreement with their lower levels of apoptosis. Caspase-3 cleavage occurred in the EBV-negative etoposide-treated cells but not in the EBV-positive cells. The results indicate that apoptosis resistance in EBV-infected B cell lymphomas is promoted by an inactive caspase-3 pathway and elevated expression of Bcl-2 that is not altered by etoposide drug treatment.

Interindividual variation of isolated muscle performance and fibre-type composition in the toad Bufo viridus

Interindividual analyses of physiological performance represent one of the most powerful tools for identifying functional positive and negative linkages between various performance traits. In this study we investigated functional linkages in the whole-gastrocnemius performance of juvenile Bufo viridis by examining interindividual variation in in vitro muscle performance and muscle fibre-type composition. We used the work-loop technique to investigate the maximum in vitro power output and fatigue resistance of the gastrocnemius muscle during repeated sets of three cycles at the cycle frequency of 5 Hz, simulating an intermittent style of locomotion. We found several significant correlations between different measures of in vitro muscle performance, including a negative correlation between maximum net power output and fatigue resistance of power, indicating functional trade-offs between these performance traits. We also investigated the extent of individual variation in the proportions of different fibre types, and tested for correlations between individual variation in muscle fibre-type composition and the previously measured isolated muscle performance. Fast glycolytic fibres represented 84.0+/-3.4% of the muscle, while the combined slow oxidative and fast oxidative-glycolytic fibres represented 16+/-3.4%. We found no significant correlations between measures of in vitro muscle performance and the proportion of different fibre types in the gastrocnemius muscle. However, despite this lack of correlation between whole-muscle performance and muscle fibre-type composition data, we suggest the functional linkages detected between different measures of in vitro muscular performance have important ecological and evolutionary consequences.

Seclusion use with children and adolescents: an Australian experience

Objective: To summarize the current state of knowledge on the use of seclusion and restraint with children and adolescents and to report the findings of an exploratory study to identify factors that place a child or adolescent at increased risk of seclusion during their admission. Method: Literature searches were undertaken on MEDLINE, CINAHL and PsycINFO databases. Articles were identified that focused specifically on seclusion and restraint use with children and adolescents or contained material significant to this population. The study reports findings from a retrospective review of patient charts, seclusion registers and staffing from an Australian acute inpatient facility. Results: The data available in regard to seclusion use in this population is limited and flawed. Further research is needed on the use and outcomes of seclusion and restraint and on alternative measures in the containment of dangerousness. Both the literature and this study find that patients with certain factors are at increased risk of being secluded during an inpatient stay. These factors include being male, diagnoses of disruptive behaviour disorder and a previous history of physical abuse. Staffing factors did not show a relationship to the use of seclusion. Conclusions: There are patient factors that predict increased risk of seclusion; these factors and their interrelationships require further elucidation. Further research is also needed on the outcomes, both positive and negative, of seclusion use and of alternatives to seclusion.

Acceptability and feasibility of a community-based screening programme for melanoma in Australia

The evaluation of a community-based screening programme for melanoma (SkinWatch) in 18 regional communities (total adult population >30 years 63 035) in Queensland, Australia is described. The aim of the SkinWatch programme was to promote whole-body skin screening for melanoma by primary care physicians. The programme included community education, education and support for local medical practitioners and open-access skin screening clinics. Programme delivery was achieved through assistance of local volunteers. All programme activities and resources were recorded for process evaluation. A baseline telephone survey (n = 3110) and a telephone survey four months after programme launch (n = 680) assessed community awareness of the SkinWatch programme and, 37 face-to-face interviews with community members, doctors and community leaders were conducted to assess satisfaction with the programme. A sample of 1043 of 16 383 residents who attended the skin screening clinics provided as part of the programme were interviewed to assess reasons for attending, and positive and negative aspects of SkinWatch programme. Community awareness of the SkinWatch programme increased by over 30% (p < 0.001) within four months of the start of the programme. Interview participants described the SkinWatch programme as a useful service for the communities and 90% stated they would revisit the clinics. A total of 43% of all attendees were over 50 years old, and nearly 50% were men. These findings demonstrate the acceptability and feasibility of a community-based screening programme for melanoma in rural areas. Volunteers were instrumental in increasing community ownership of and involvement in the SkinWatch programme.

Bistability and switching in the lysis/lysogeny genetic regulatory network of bacteriophage lambda

Bistability and switching are two important aspects of the genetic regulatory network of phage. Positive and negative feedbacks are key regulatory mechanisms in this network. By the introduction of threshold values, the developmental pathway of A phage is divided into different stages. If the protein level reaches a threshold value, positive or negative feedback will be effective and regulate the process of development. Using this regulatory mechanism, we present a quantitative model to realize bistability and switching of phage based on experimental data. This model gives descriptions of decisive mechanisms for different pathways in induction. A stochastic model is also introduced for describing statistical properties of switching in induction. A stochastic degradation rate is used to represent intrinsic noise in induction for switching the system from the lysogenic pathway to the lysis pathway. The approach in this paper represents an attempt to describe the regulatory mechanism in genetic regulatory network under the influence of intrinsic noise in the framework of continuous models. (C) 2003 Elsevier Ltd. All rights reserved.

Parent management training and Asperger syndrome - A randomized controlled trial to evaluate a parent based intervention

This controlled trial of a parent management intervention aimed to increase parental competence in management of problem behaviours associated with Asperger syndrome. The intervention compared two formats, a 1 day workshop and six individual sessions. Measures were taken on three occasions: pre-intervention, at 4 weeks, and at 3 month follow-up. Variables of interest were number and intensity of problem behaviours, and parent evaluation of social interaction skills. Results showed parents reporting fewer and lower intensity of problem behaviours and increased social interactions at 4 weeks and 3 months. Results held across formats and suggest that parent management training can provide an effective intervention for parents of a child with Asperger syndrome. Group differences on outcome measures and in the use of strategies are discussed along with limitations of the study.

The effect of ionic strength variation and anion competition on the development of nitrate accumulations in variable charge subsoils

The leaching of N fertilisers has led to the formation of nitrate (NO3) accumulations in deep subsoils (>5 m depth) of the Johnstone River catchment. This paper outlines the chemical mechanism by which these NO3 accumulations are formed and maintained. This was achieved via a series of column experiments designed to investigate NO3 leaching in relation to the soil charge chemistry and the competition of anions for exchange sites. The presence of variable charge minerals has led to the formation positive surface charge within these profiles. An increase in the soil solution ionic strength accompanying the fertiliser leaching front acts to increase the positive (and negative) charge density, thus providing adsorption sites for NO3. A decrease in the soil solution ionic strength occurs after the fertiliser pulse moves past a point in the profile, due to dilution with incoming rainwater. Nitrate is then released from the exchange back into the soil solution, thus buffering the decrease in the soil solution ionic strength. Since NO3 was adsorbed throughout the profile in this experiment it does not effectively explain the situation occurring in the field. Previous observations of the sulfate (SO4) profile distribution indicated that large SO4 accumulations in the upper profile may influence the NO3 distribution through competition for adsorption sites. A subsequent experiment investigating the effect of SO4 additions on NO3 leaching showed that NO3 adsorption was minimal in the upper profile. Adsorption of NO3 did occur, though only in the region of the profile where SO4 occupancy was low, i.e. in the lower profile. Therefore, the formation of the NO3 accumulations is dependent on the variable charge mineralogy, the variation of charge density with soil solution ionic strength, and the effects of SO4 competition for adsorption sites.

Economics and psychology in the twenty-first century

This paper begins by exploring four different possible forms of relationship between economics and psychology, which have different connotations in terms of the relative status of the two disciplines. It then focuses on the future for one of these, psychological economics. After setting out the hardcore axioms and positive and negative heuristics of a research programme in psychological economics, it explores institutional and psychological barriers to the success of such a research programme in the context of both research and teaching.

The complexity of drinking: Interactions between the cognitive and behavioural determinants of alcohol consumption

This study expanded the earlier work conducted by this laboratory ( Hasking, P.A. and Oei, T.P.S. (2002a) . The differential role of alcohol expectancies, drinking refusal self-efficacy and coping resources in predicting alcohol consumption in community and clinical samples. Addiction Research and Theory , 10 , 465-494), by examining the independent and interactive effects of avoidant coping strategies, positive and negative expectancies and self-efficacy, in predicting volume and frequency of alcohol consumption in a sample of community drinkers. Differential relationships were found between the variables when predicting the two consumption measures. Specifically, while self-efficacy, seeking social support for emotional reasons and using drugs or alcohol to cope were independently related to both volume and frequency of drinking, complex interactions with positive and negative alcohol expectancies were also found. These interactions are discussed in terms of the cognitive and behavioural mechanisms thought to underlie drinking behaviour.