Controls on iron in soils and soil waters of a forested, coastal catchment in subtropical Australia

Soluble organic matter derived from exotic Pinus vegetation forms stronger complexes with iron (Fe) than the soluble organic matter derived from most native Australian species. This has lead to concern about the environmental impacts related to the establishment of extensive exotic Pinus plantations in coastal southeast Queensland, Australia. It has been suggested that the Pinus plantations may enhance the solubility of Fe in soils by increasing the amount of organically complexed Fe. While this remains inconclusive, the environmental impacts of an increased flux of dissolved, organically complexed Fe from soils to the fluvial system and then to sensitive coastal ecosystems are potentially damaging. Previous work investigated a small number of samples, was largely laboratory based and had limited application to field conditions. These assessments lacked field-based studies, including the comparison of the soil water chemistry of sites associated with Pinus vegetation and undisturbed native vegetation. In addition, the main controls on the distribution and mobilisation of Fe in soils of this subtropical coastal region have not been determined. This information is required in order to better understand the relative significance of any Pinus enhanced solubility of Fe. The main aim of this thesis is to determine the controls on Fe distribution and mobilisation in soils and soil waters of a representative coastal catchment in southeast Queensland (Poona Creek catchment, Fraser Coast) and to test the effect of Pinus vegetation on the solubility and speciation of Fe. The thesis is structured around three individual papers. The first paper identifies the main processes responsible for the distribution and mobilisation of labile Fe in the study area and takes a catchment scale approach. Physicochemical attributes of 120 soil samples distributed throughout the catchment are analysed, and a new multivariate data analysis approach (Kohonen’s self organising maps) is used to identify the conditions associated with high labile Fe. The second paper establishes whether Fe nodules play a major role as an iron source in the catchment, by determining the genetic mechanism responsible for their formation. The nodules are a major pool of Fe in much of the region and previous studies have implied that they may be involved in redox-controlled mobilisation and redistribution of Fe. This is achieved by combining a detailed study of a ferric soil profile (morphology, mineralogy and micromorphology) with the distribution of Fe nodules on a catchment scale. The third component of the thesis tests whether the concentration and speciation of Fe in soil solutions from Pinus plantations differs significantly from native vegetation soil solutions. Microlysimeters are employed to collect unaltered, in situ soil water samples. The redox speciation of Fe is determined spectrophotometrically and the interaction between Fe and dissolved organic matter (DOM) is modelled with the Stockholm Humic Model. The thesis provides a better understanding of the controls on the distribution, concentration and speciation of Fe in the soils and soil waters of southeast Queensland. Reductive dissolution is the main mechanism by which mobilisation of Fe occurs in the study area. Labile Fe concentrations are low overall, particularly in the sandy soils of the coastal plain. However, high labile Fe is common in seasonally waterlogged and clay-rich soils which are exposed to fluctuating redox conditions and in organic-rich soils adjacent to streams. Clay-rich soils are most common in the upper parts of the catchment. Fe nodules were shown to have a negligible role in the redistribution of dissolved iron in the catchment. They are formed by the erosion, colluvial transport and chemical weathering of iron-rich sandstones. The ferric horizons, in which nodules are commonly concentrated, subsequently form through differential biological mixing of the soil. Whereas dissolution/ reprecipitation of the Fe cements is an important component of nodule formation, mobilised Fe reprecipitates locally. Dissolved Fe in the soil waters is almost entirely in the ferrous form. Vegetation type does not affect the concentration and speciation of Fe in soil waters, although Pinus DOM has greater acidic functional group site densities than DOM from native vegetation. Iron concentrations are highest in the high DOM soil waters collected from sandy podosols, where they are controlled by redox potential. Iron concentrations are low in soil solutions from clay and iron oxide rich soils, in spite of similar redox potentials. This is related to stronger sorption to the reactive clay and iron oxide mineral surfaces in these soils, which reduces the amount of DOM available for microbial metabolisation and reductive dissolution of Fe. Modelling suggests that Pinus DOM can significantly increase the amount of truly dissolved ferric iron remaining in solution in oxidising conditions. Thus, inputs of ferrous iron together with Pinus DOM to surface waters may reduce precipitation of hydrous ferric oxides and increase the flux of dissolved iron out of the catchment. Such inputs are most likely from the lower catchment, where podosols planted with Pinus are most widely distributed. Significant outcomes other than the main aims were also achieved. It is shown that mobilisation of Fe in podosols can occur as dissolved Fe(II) rather than as Fe(III)-organic complexes. This has implications for the large body of work which assumes that Fe(II) plays a minor role. Also, the first paper demonstrates that a data analysis approach based on Kohonen’s self organising maps can facilitate the interpretation of complex datasets and can help identify geochemical processes operating on a catchment scale.

The relationship between parents’ self-efficacy beliefs, outcome expectations, child behaviour, and management of atopic dermatitis

Atopic dermatitis (AD) is a chronic inflammatory skin condition, characterized by intense pruritis, with a complex aetiology comprising multiple genetic and environmental factors. It is a common chronic health problem among children, and along with other allergic conditions, is increasing in prevalence within Australia and in many countries worldwide. Successful management of childhood AD poses a significant and ongoing challenge to parents of affected children. Episodic and unpredictable, AD can have profound effects on children’s physical and psychosocial wellbeing and quality of life, and that of their caregivers and families. Where concurrent child behavioural problems and parenting difficulties exist, parents may have particular difficulty achieving adequate and consistent performance of the routine management tasks that promote the child’s health and wellbeing. Despite frequent reports of behaviour problems in children with AD, past research has neglected the importance of child behaviour to parenting confidence and competence with treatment. Parents of children with AD are also at risk of experiencing depression, anxiety, parenting stress, and parenting difficulties. Although these factors have been associated with difficulty in managing other childhood chronic health conditions, the nature of these relationships in the context of child AD management has not been reported. This study therefore examined relationships between child, parent, and family variables, and parents’ management of child AD and difficult child behaviour, using social cognitive and self-efficacy theory as a guiding framework. The study was conducted in three phases. It employed a quantitative, cross-sectional study design, accessing a community sample of 120 parents of children with AD, and a sample of 64 child-parent dyads recruited from a metropolitan paediatric tertiary referral centre. In Phase One, instruments designed to measure parents’ self-reported performance of AD management tasks (Parents’ Eczema Management Scale – PEMS) and parents’ outcome expectations of task performance (Parents’ Outcome Expectations of Eczema Management Scale – POEEMS) were adapted from the Parental Self-Efficacy with Eczema Care Index (PASECI). In Phase Two, these instruments were used to examine relationships between child, parent, and family variables, and parents’ self-efficacy, outcome expectations, and self-reported performance of AD management tasks. Relationships between child, parent, and family variables, parents’ self-efficacy for managing problem behaviours, and reported parenting practices, were also examined. This latter focus was explored further in Phase Three, in which relationships between observed child and parent behaviour, and parent-reported self-efficacy for managing both child AD and problem behaviours, were explored. Phase One demonstrated the reliability of both PEMS and POEEMS, and confirmed that PASECI was reliable and valid with modification as detailed. Factor analyses revealed two-factor structures for PEMS and PASECI alike, with both scales containing factors related to performing routine management tasks, and managing the child’s symptoms and behaviour. Factor analysis was also applied to POEEMS resulting in a three-factor structure. Factors relating to independent management of AD by the parent, involving healthcare professionals in management, and involving the child in management of AD were found. Parents’ self-efficacy and outcome expectations had a significant influence on self-reported task performance. In Phase Two, relationships emerged between parents’ self-efficacy and self-reported performance of AD management tasks, and AD severity, child behaviour difficulties, parent depression and stress, conflict over parenting issues, and parents’ relationship satisfaction. Using multiple linear regressions, significant proportions of variation in parents’ self-efficacy and self-reported performance of AD management tasks were explained by child behaviour difficulties and parents’ formal education, and self-efficacy emerged as a likely mediator for the relationships between both child behaviour and parents’ education, and performance of AD management tasks. Relationships were also found between parents’ self-efficacy for managing difficult child behaviour and use of dysfunctional parenting strategies, and child behaviour difficulties, parents’ depression and stress, conflict over parenting issues, and relationship satisfaction. While significant proportions of variation in self-efficacy for managing child behaviour were explained by both child behaviour and family income, family income was the only variable to explain a significant proportion of variation in parent-reported use of dysfunctional parenting strategies. Greater use of dysfunctional parenting strategies (both lax and authoritarian parenting) was associated with more severe AD. Parents reporting lower self-efficacy for managing AD also reported lower self-efficacy for managing difficult child behaviour; likewise, less successful self-reported performance of AD management tasks was associated with greater use of dysfunctional parenting strategies. When child and parent behaviour was directly observed in Phase Three, more aversive child behaviour was associated with lower self-efficacy, less positive outcome expectations, and poorer self-reported performance of AD management tasks by parents. Importantly, there were strong positive relationships between these variables (self-efficacy, outcome expectations, and self-reported task performance) and parents’ observed competence when providing treatment to their child. Less competent performance was also associated with greater parent-reported child behaviour difficulties, parent depression and stress, parenting conflict, and relationship dissatisfaction. Overall, this study revealed the importance of child behaviour to parents’ confidence and practices in the contexts of child AD and child behaviour management. Parents of children with concurrent AD and behavioural problems are at particular risk of having low self-efficacy for managing their child’s AD and difficult behaviour. Children with more severe AD are also at higher risk of behaviour problems, and thus represent a high-risk group of children whose parents may struggle to manage the disease successfully. As one of the first studies to examine the role and correlates of parents’ self-efficacy in child AD management, this study identified a number of potentially modifiable factors that can be targeted to enhance parents’ self-efficacy, and improve parent management of child AD. In particular, interventions should focus on child behaviour and parenting issues to support parents caring for children with AD and improve child health outcomes. In future, findings from this research will assist healthcare teams to identify parents most in need of support and intervention, and inform the development and testing of targeted multidisciplinary strategies to support parents caring for children with AD.

Comparative study of coagulase negative Staphylococci (CoNS) from clinical isolates, skin and nasal sources

Staphylococci are important pathogenic bacteria responsible for a range of diseases in humans. The most frequently isolated microorganisms in a hospital microbiology laboratory are staphylococci. The general classification of staphylococci divides them into two major groups; Coagulase-positive staphylococci (e.g. Staphylococcus aureus) and Coagulase-negative staphylococci (e.g. Staphylococcus epidermidis). Coagulase-negative staphylococcal (CoNS) isolates include a variety of species and many different strains but are often dominated by the most important organism of this group, S. epidermidis. Currently, these organisms are regarded as important pathogenic organisms causing infections related to prosthetic materials and surgical wounds. A significant number of S. epidermidis isolates are also resistant to different antimicrobial agents. Virulence factors in CoNS are not very clearly established and not well documented. S. epidermidis is evolving as a resistant and powerful microbe related to nosocomial infections because it has different properties which independently, and in combination, make it a successful infectious agent, especially in the hospital environment. Such characteristics include biofilm formation, drug resistance and the evolution of genetic variables. The purpose of this project was to develop a novel SNP genotyping method to genotype S. epidermidis strains originating from hospital patients and healthy individuals. High-Resolution Melt Analysis was used to assign binary typing profiles to both clinical and commensal strains using a new bioinformatics approach. The presence of antibiotic resistance genes and biofilm coding genes were also interrogated in these isolates.

The ghrelin signalling system is involved in the consumption of sweets

The gastric-derived orexigenic peptide ghrelin affects brain circuits involved in energy balance as well as in reward. Indeed, ghrelin activates an important reward circuit involved in natural- as well as drug-induced reward, the cholinergic-dopaminergic reward link. It has been hypothesized that there is a common reward mechanism for alcohol and sweet substances in both animals and humans. Alcohol dependent individuals have higher craving for sweets than do healthy controls and the hedonic response to sweet taste may, at least in part, depend on genetic factors. Rat selectively bred for high sucrose intake have higher alcohol consumption than non-sucrose preferring rats and vice versa. In the present study a group of alcohol-consuming individuals selected from a population cohort was investigated for genetic variants of the ghrelin signalling system in relation to both their alcohol and sucrose consumption. Moreover, the effects of GHS-R1A antagonism on voluntary sucrose- intake and operant self-administration, as well as saccharin intake were investigated in preclinical studies using rodents. The effects of peripheral grelin administration on sucrose intake were also examined. Here we found associations with the ghrelin gene haplotypes and increased sucrose consumption, and a trend for the same association was seen in the high alcohol consumers. The preclinical data show that a GHS-R1A antagonist reduces the intake and self-administration of sucrose in rats as well as saccharin intake in mice. Further, ghrelin increases the intake of sucrose in rats. Collectively, our data provide a clear indication that the GHS-R1A antagonists reduces and ghrelin increases the intake of rewarding substances and hence, the central ghrelin signalling system provides a novel target for the development of drug strategies to treat addictive behaviours. © 2011 Landgren et al.

Modeling key compromise impersonation attacks on group key exchange protocols

Two-party key exchange (2PKE) protocols have been rigorously analyzed under various models considering different adversarial actions. However, the analysis of group key exchange (GKE) protocols has not been as extensive as that of 2PKE protocols. Particularly, an important security attribute called key compromise impersonation (KCI) resilience has been completely ignored for the case of GKE protocols. Informally, a protocol is said to provide KCI resilience if the compromise of the long-term secret key of a protocol participant A does not allow the adversary to impersonate an honest participant B to A. In this paper, we argue that KCI resilience for GKE protocols is at least as important as it is for 2PKE protocols. Our first contribution is revised definitions of security for GKE protocols considering KCI attacks by both outsider and insider adversaries. We also give a new proof of security for an existing two-round GKE protocol under the revised security definitions assuming random oracles. We then show how to achieve insider KCIR in a generic way using a known compiler in the literature. As one may expect, this additional security assurance comes at the cost of an extra round of communication. Finally, we show that a few existing protocols are not secure against outsider KCI attacks. The attacks on these protocols illustrate the necessity of considering KCI resilience for GKE protocols.

Reduced variance in monozygous twins for multiple MR parameters : implications for disease studies and the genetic basis of brain structure

Twin studies offer the opportunity to determine the relative contribution of genes versus environment in traits of interest. Here, we investigate the extent to which variance in brain structure is reduced in monozygous twins with identical genetic make-up. We investigate whether using twins as compared to a control population reduces variability in a number of common magnetic resonance (MR) structural measures, and we investigate the location of areas under major genetic influences. This is fundamental to understanding the benefit of using twins in studies where structure is the phenotype of interest. Twenty-three pairs of healthy MZ twins were compared to matched control pairs. Volume, T2 and diffusion MR imaging were performed as well as spectroscopy (MRS). Images were compared using (i) global measures of standard deviation and effect size, (ii) voxel-based analysis of similarity and (iii) intra-pair correlation. Global measures indicated a consistent increase in structural similarity in twins. The voxel-based and correlation analyses indicated a widespread pattern of increased similarity in twin pairs, particularly in frontal and temporal regions. The areas of increased similarity were most widespread for the diffusion trace and least widespread for T2. MRS showed consistent reduction in metabolite variation that was significant in the temporal lobe N-acetylaspartate (NAA). This study has shown the distribution and magnitude of reduced variability in brain volume, diffusion, T2 and metabolites in twins. The data suggest that evaluation of twins discordant for disease is indeed a valid way to attribute genetic or environmental influences to observed abnormalities in patients since evidence is provided for the underlying assumption of decreased variability in twins.

Possible genetic predisposition to lymphedema after breast cancer

Background: Known risk factors for secondary lymphedema only partially explain who develops lymphedema following cancer, suggesting that inherited genetic susceptibility may influence risk. Moreover, identification of molecular signatures could facilitate lymphedema risk prediction prior to surgery or lead to effective drug therapies for prevention or treatment. Recent advances in the molecular biology underlying development of the lymphatic system and related congenital disorders implicate a number of potential candidate genes to explore in relation to secondary lymphedema. Methods and Results: We undertook a nested case-control study, with participants who had developed lymphedema after surgical intervention within the first 18 months of their breast cancer diagnosis serving as cases (n=22) and those without lymphedema serving as controls (n=98), identified from a prospective, population-based, cohort study in Queensland, Australia. TagSNPs that covered all known genetic variation in the genes SOX18, VEGFC, VEGFD, VEGFR2, VEGFR3, RORC, FOXC2, LYVE1, ADM and PROX1 were selected for genotyping. Multiple SNPs within three receptor genes, VEGFR2, VEGFR3 and RORC, were associated with lymphedema defined by statistical significance (p<0.05) or extreme risk estimates (OR<0.5 or >2.0). Conclusions: These provocative, albeit preliminary, findings regarding possible genetic predisposition to secondary lymphedema following breast cancer treatment warrant further attention for potential replication using larger datasets.

Verbal instruction abolishes fear conditioned to racial out-group faces

Previous research has shown resistance to extinction of fear conditioned to racial out-group faces, suggesting that these stimuli may be subject to prepared fear learning. The current study replicated and extended previous research by using a different racial out-group, and testing the prediction that prepared fear learning is unaffected by verbal instructions. Four groups of Caucasian participants were trained with male in-group (Caucasian) or out-group (Chinese) faces as conditional stimuli; one paired with an electro-tactile shock (CS+) and one presented alone (CS). Before extinction, half the participants were instructed that no more shocks would be presented. Fear conditioning, indexed by larger electrodermal responses to, and blink startle modulation during the CS+, occurred during acquisition in all groups. Resistance to extinction of fear learning was found only in the racial out-group, no instruction condition. Fear conditioned to a racial out-group face was reduced following verbal instructions, contrary to predictions for the nature of prepared fear learning.

A fast tabu search algorithm for the group shop scheduling problem

Three types of shop scheduling problems, the flow shop, the job shop and the open shop scheduling problems, have been widely studied in the literature. However, very few articles address the group shop scheduling problem introduced in 1997, which is a general formulation that covers the three above mentioned shop scheduling problems and the mixed shop scheduling problem. In this paper, we apply tabu search to the group shop scheduling problem and evaluate the performance of the algorithm on a set of benchmark problems. The computational results show that our tabu search algorithm is typically more efficient and faster than the other methods proposed in the literature. Furthermore, the proposed tabu search method has found some new best solutions of the benchmark instances.

Has increasing the age for child passengers to wear child restraints improved the extent to which they are used? Results from an Australian focus group and survey study.

Acknowledgement that many children in Australia travel in restraints that do not offer them the best protection has led to recent changes in legislation such that the type of restraint for children under 7 years is now specified. This paper reports the results of two studies (observational; focus group/ survey) carried out in the state of Queensland to evaluate the effectiveness of these changes to the legislation. Observations suggested that almost all of the children estimated as aged 0-12 years were restrained (95%). Analysis of the type of restraint used for target-aged children (0-6 year olds) suggests that the proportion using an age-appropriate restraint has increased by an estimated 7% since enactment of the legislation. However, around 1 in 4 children estimated as aged under 7 years were using restraints too large for good fit. Results from the survey and focus group suggested parents were supportive of the changes in legislation. Non-Indigenous parents agreed that the changes had been necessary, were effective at getting children into the right restraints, were easy to understand as well as making it clear what restraint to use with children. Moreover, they did not see the legislation as too complicated or too hard to comply with. Indigenous parents who participated in a focus group also regarded the legislation as improving children’s safety. However, they identified the cost of restraints as an important barrier to compliance. In summary, the legislation appears to have had a positive effect on compliance levels and on raising parental awareness of the need to restrain children child-specific restraints for longer. However, it would seem that an important minority of parents transition their children into larger restraints too early for optimal protection. Intervention efforts should aim to better inform these parents about appropriate ages for transition, especially from forward facing childseats. This could potentially be through use of other important transitions that occur at the same age, such as starting school. The small proportion of parents who do not restrain their children at all are also an important community sector to target. Finally, obtaining restraints presents a significant barrier to compliance for parents on limited incomes and interventions are needed to address this.

Group law computations on Jacobians of hyperelliptic Curves

We derive an explicit method of computing the composition step in Cantor’s algorithm for group operations on Jacobians of hyperelliptic curves. Our technique is inspired by the geometric description of the group law and applies to hyperelliptic curves of arbitrary genus. While Cantor’s general composition involves arithmetic in the polynomial ring F_q[x], the algorithm we propose solves a linear system over the base field which can be written down directly from the Mumford coordinates of the group elements. We apply this method to give more efficient formulas for group operations in both affine and projective coordinates for cryptographic systems based on Jacobians of genus 2 hyperelliptic curves in general form.

Negotiating group dynamics for better safety performance

Safety psychology and workplace safety Commitment, Motivational and attitudinal components of safety Leadership Group Dynamics and Group Change Case Study from Construction

Genetic evidence for the vital function of osterix in cementogenesis

To date, attempts to regenerate a complete tooth, including the critical periodontal tissues associated with the tooth root, have not been successful. Controversy still exists regarding the origin of the cell source for cellular cementum (epithelial or mesenchymal). This disagreement may be partially due to a lack of understanding of the events leading to the initiation and development of the tooth roots and supportive tissues, such as the cementum. Osterix (OSX) is a transcriptional factor essential for osteogenesis, but its role in cementogenesis has not been addressed. In the present study, we first documented a close relationship between the temporal- and spatial-expression pattern of OSX and the formation of cellular cementum. We then generated 3.6 Col 1-OSX transgenic mice, which displayed accelerated cementum formation vs. WT controls. Importantly, the conditional deletion of OSX in the mesenchymal cells with two different Cre systems (the 2.3 kb Col 1 and an inducible CAG-CreER) led to a sharp reduction in cellular cementum formation (including the cementum mass and mineral deposition rate) and gene expression of dentin matrix protein 1 (DMP1) by cementocytes. However, the deletion of the OSX gene after cellular cementum formed did not alter the properties of the mature cementum as evaluated by backscattered SEM and resin-cast SEM. Transient transfection of Osx in the cementoblasts in vitro significantly inhibited cell proliferation and increased cell differentiation and mineralization. Taken together, these data support 1) the mesenchymal origin of cellular cementum (from PDL progenitor cells); 2) the vital role of OSX in controlling the formation of cellular cementum; and 3) the limited remodeling of cellular cementum in adult mice.

Promoting Adult Resilience (PAR): Group Leaders Manual

RAP-A was developed to meet the need for a universal resilience building program for teenagers which could be readily implemented in a school setting. A universal program targets all teenagers in a particular grade as opposed to those at higher risk for depression (indicated or selective approaches) or a treatment group. It is easier to recruit and engage adolescents in a universal approach where students do not face the risk of stigmatisation by being singled out for intervention. The Resourceful Adolescent Program (RAP: Shochet, Holland & Whitefield, 1997) was developed to meet this need.