Differential effects of aging on spatial learning through exploratory navigation and map reading

It has been shown that abilities in spatial learning and memory are adversely affected by aging. The present study was conducted to investigate whether increasing age has equal consequences for all types of spatial learning or impacts certain types of spatial learning selectively. Specifically, two major types of spatial learning, exploratory navigation and map reading, were contrasted. By combining a neuroimaging finding that the medial temporal lobe (MTL) is especially important for exploratory navigation and a neurological finding that the MTL is susceptible to age-related atrophy, it was hypothesized that spatial learning through exploratory navigation would exhibit a greater decline in later life than spatial learning through map reading. In an experiment, young and senior participants learned locations of landmarks in virtual environments either by navigating in them in the first-person perspective or by seeing aerial views of the environments. Results showed that senior participants acquired less accurate memories of the layouts of landmarks than young participants when they navigated in the environments, but the two groups did not differ in spatial learning performance when they viewed the environments from the aerial perspective. These results suggest that spatial learning through exploratory navigation is particularly vulnerable to adverse effects of aging, whereas elderly adults may be able to maintain their map reading skills relatively well.

The global epidemiology and contribution of cannabis use and dependence to the global burden of disease: results from the GBD 2010 study

Aim Estimate the prevalence of cannabis dependence and its contribution to the global burden of disease. Methods Systematic reviews of epidemiological data on cannabis dependence (1990-2008) were conducted in line with PRISMA and meta-analysis of Observational Studies in Epidemiology (MOOSE) guidelines. Culling and data extraction followed protocols, with cross-checking and consistency checks. DisMod-MR, the latest version of generic disease modelling system, redesigned as a Bayesian meta-regression tool, imputed prevalence by age, year and sex for 187 countries and 21 regions. The disability weight associated with cannabis dependence was estimated through population surveys and multiplied by prevalence data to calculate the years of life lived with disability (YLDs) and disability-adjusted life years (DALYs). YLDs and DALYs attributed to regular cannabis use as a risk factor for schizophrenia were also estimated. Results There were an estimated 13.1 million cannabis dependent people globally in 2010 (point prevalence0.19% (95% uncertainty: 0.17-0.21%)). Prevalence peaked between 20-24 yrs, was higher in males (0.23% (0.2-0.27%)) than females (0.14% (0.12-0.16%)) and in high income regions. Cannabis dependence accounted for 2 million DALYs globally (0.08%; 0.05-0.12%) in 2010; a 22% increase in crude DALYs since 1990 largely due to population growth. Countries with statistically higher age-standardised DALY rates included the United States, Canada, Australia, New Zealand and Western European countries such as the United Kingdom; those with lower DALY rates were from Sub-Saharan Africa-West and Latin America. Regular cannabis use as a risk factor for schizophrenia accounted for an estimated 7,000 DALYs globally. Conclusion Cannabis dependence is a disorder primarily experienced by young adults, especially in higher income countries. It has not been shown to increase mortality as opioid and other forms of illicit drug dependence do. Our estimates suggest that cannabis use as a risk factor for schizophrenia is not a major contributor to population-level disease burden.

Rejected! The harmful effects of workgroup mistreatment and the moderating role of organisational norms

This program of research investigated the harmful effects of mistreatment by the workgroup, and the role of perceived rejection as a critical mediator linking mistreatment and outcomes. This research program had three primary purposes. First, the research aimed to examine the important role of workgroup mistreatment as an independent predictor of negative outcomes, over and above the influence of supervisor mistreatment. Second, the research aimed to examine the effect of perceived rejection as an explanatory variable linking workgroup mistreatment and outcomes. Finally, the moderating effect of organizational norms on the relationship between workgroup mistreatment and perceived rejection was examined. The relationships of interest were examined over four studies, using multiple methods of data collection, across part-time and full-time working samples. In Study 1 (Chapter 2), the independent role of workgroup mistreatment and the mediating role of perceived rejection were examined. One hundred and forty two part-time working participants took part in the study. The participants completed a questionnaire on workplace behaviors in their organizations. The results of hierarchical regression analyses revealed a strong harmful effect of workgroup mistreatment, independent of mistreatment by the supervisor. In addition, the results showed that perceived rejection fully mediated the relationship between workgroup mistreatment and depression and organizational based self esteem. The study highlighted that perceived rejection acts as a key underlying psychological mechanism involved in the effect of workgroup mistreatment. This study has been published in the Journal of Occupational Health Psychology. Study 2 and Study 3 were presented as one paper in Chapter 3. The aims of these two studies was to explore the effects of workgroup mistreatment on a wider range of individual and organizational level outcomes, and to provide further evidence of the mediating role of perceived rejection as observed in Study 1. The results from both studies demonstrated that workgroup mistreatment had a significant and independent role in predicting negative individual and organizational level outcomes, providing support for the findings of Study 1. In the first study, 189 participants received scenarios manipulating workgroup mistreatment and supervisor mistreatment. The results of hierarchical regression analyses revealed that workgroup mistreatment harmfully affected participants, over and above that of the supervisor. The results also demonstrated that perceived rejection mediated the positive relationships between workgroup mistreatment and depression and organizational deviance, and also the negative relationships between workgroup mistreatment and organizational based self esteem and organizational citizenship behaviors. The second study included an additional aim, to examine the moderating role of supportive organizational norms. Two hundred and twenty nine participants read scenarios that manipulated workgroup mistreatment, supervisor mistreatment and organizational norms. The results of hierarchical regression analyses revealed the significant harmful effects of workgroup mistreatment, over and above the influence of supervisor mistreatment. The results also revealed the mediating role of perceived rejection. The direct effect of positive organizational norms also emerged, consistent with previous research. In addition, the result revealed that employees who experienced supportive organizational norms were more likely to reconcile with their workgroup members after experiencing mistreatment compared to employees who experienced hostile organizational norms. Finally, an unexpected pattern on the key affective variables of depression and organizational based self esteem emerged, such that mistreatment led to more negative outcomes in the supportive norms condition than in the hostile condition, where employees appeared to be desensitized. This paper is currently under review at the Journal of Applied Social Psychology. In Study 4 (Chapter 4), the overall model of workplace mistreatment was tested on a sample of full-time workers in an applied setting. One hundred and seventy two adults took part in the study. Participants were required to evaluate their workplace regarding mistreatment and organizational norms and to report their own psychological, behavioral and organizational outcomes. The results revealed that workgroup mistreatment was associated with increased depression, stress and avoidance, over and above supervisor mistreatment. In addition, the results revealed that perceived rejection acted as an explanatory variable linking workgroup mistreatment to a number of outcomes. Furthermore, the moderating role of hostile organizational norms emerged on depression, stress, reconciliation and avoidance. This paper is currently under review at the Journal of Occupational Health Psychology. Overall, the four studies provided empirical support for the majority of the hypotheses. The effects were demonstrated for a range of psychological, behavioral, and organizational level outcomes, using multiple methods of data collection, across part-time and full-time workers. At the conclusion of the thesis (Chapter 5), an overall summary is provided of the findings across all four studies, practical and theoretical implications and research directions.

Monoclonal antibody screening of a phage-displayed random peptide library reveals mimotopes of chemokine receptor CCR5: Implications for the tertiary structure of the receptor and for an n-terminal binding site for HIV-1 gp120

The chemokine receptor CCR5 contains seven transmembrane-spanning domains. It binds chemokines and acts as co-receptor for macrophage (m)-tropic (or R5) strains of HIV-1. Monoclonal antibodies (mAb) to CCR5, 3A9 and 5C7, were used for biopanning a nonapeptide cysteine (C)-constrained phage-displayed random peptide library to ascertain contact residues and define tertiary structures of possible epitopes on CCR5. Reactivity of antibodies with phagotopes was established by enzyme-linked immunosorbent assay (ELISA). mAb 3A9 identified a phagotope C-HASIYDFGS-C (3A9/1), and 5C7 most frequently identified C-PHWLRDLRV-C (5C7/1). Corresponding peptides were synthesized. Phagotopes and synthetic peptides reacted in ELISA with corresponding antibodies and synthetic peptides inhibited antibody binding to the phagotopes. Reactivity by immunofluorescence of 3A9 with CCR5 was strongly inhibited by the corresponding peptide. Both mAb 3A9 and 5C7 reacted similarly with phagotopes and the corresponding peptide selected by the alternative mAb. The sequences of peptide inserts of phagotopes could be aligned as mimotopes of the sequence of CCR5. For phage 3A9/1, the motif SIYD aligned to residues at the N terminus and FG to residues on the first extracellular loop; for 5C7/1, residues at the N terminus, first extracellular loop, and possibly the third extracellular loop could be aligned and so would contribute to the mimotope. The synthetic peptides corresponding to the isolated phagotopes showed a CD4-dependent reactivity with gp120 of a primary, m-tropic HIV-1 isolate. Thus reactivity of antibodies raised to CCR5 against phage-displayed peptides defined mimotopes that reflect binding sites for these antibodies and reveal a part of the gp120 binding sites on CCR5.

“Come in and look around.” Professional development of student teachers through public pedagogy in a library exhibition

This paper describes a public pedagogy project embedded into "The Global Teacher", a subject within the Bachelor of Education program for student teachers at an Australian university. The subject provides a global perspective on socio-political issues that shape education. In 2013, The Global Teacher introduced an approach that asked student teachers to create a museum-style exhibition depicting six global education themes. This exhibition was displayed in the State Library and the public were invited to engage with the installations and the student teachers who created them. Our paper describes how the project was implemented by means of close collaboration between the QUT teacher educators, curators at the State Library of Queensland (SLQ), and student groups working on visually translating their understandings of global educational issues into a public exhibition. We discuss what was learned by our students and ourselves, as teacher educators, by engaging in this public pedagogy.