Investigation of compounds causing water repellency in the rhizosphere of sandy soils from a wide range of locations.

Although soils are generally considered to wet readily, some are actually water repellent at the surface and in the rhizosphere. This phenomenon occurs at low to moderate moisture contents and has been reported from soils under a range of vegetation types and from many regions around the globe. Water repellency in soils can have serious environmental implications including reduced seed germination and plant growth as well as irrigation efficiency, accelerated soil erosion, and enhanced leaching of agrochemicals through preferential flow. it has been proposed that water repellency is caused by the accumulation of hydrophobic organic compounds released as root exudates, microbial byproducts or from decomposing organic matter, which are deposited on mineral or aggregate surfaces, or are present as interstitial matter, Few studies to date have attempted to isolate and characterize these compounds and their structure is therefore only poorly understood, These studies have generally focussed on only a single soil or a small range of samples, have not included non-repellent soils as a control and have not always been able to demonstrate that the substances isolated are indeed responsible for repellency formation.

This study reports on the first part (extraction procedures) of a research programme addressing these gaps in current knowledge by investigating a wide range of severely repellent and wettable ‘control’ samples from different countries, and by including assessments of extraction efficiency and ability of extracts to cause repellency. Analytical methods include DRIFT (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) of soils and IR (Infrared) analysis of extracts.

Key findings are that (i) soil sample heating after extraction is valuable in assessing the effectiveness of the extraction procedure, (ii) Soxhlet extraction using isopropanol/ ammonia (70/30 v/v) was the most effective method in extracting hydrophobic compounds, while leaving the ability of extracted compounds to induce water repellency virtually unaffected, (iii) wettable control soils also contain hydrophobic substances capable of inducing water repellency, (iv) the amount of organic compounds extracted was poorly related to sample repellency, indicating that compounds responsible for repellency may only represent a small fraction of the extract, (v) differences in extraction efficiency between different samples indicate that the compounds responsible may differ generically and/or in terms of their bonding to minerals, and (vi) the combination of repellency assessments with DRIFT on soils and JR on extracts used with internal standards has considerable potential to allow quantification of CH bearing organic matter in the soil, the efficiency of extraction processes for its removal, and its significance in causing water repellency in soils.

Troubling identities : teacher education students' constructions of class and ethnicity

This paper reports on a research project that explored how student teachers understand ethnic and classed difference as it relates to themselves and their students. Discourses of schooling can shape students ethnic and classed identities, frequently positioning non-mainstream students as 'other' and marginalizing them. Significant numbers of our teacher education students have limited experience of diverse educational settings, having mainly attended white middle-class schools as students and as student teachers. Working with diverse student populations productively depends on teachers recognising and valuing difference. The ways in which they engage with students whose ethnic and classed identities are different from their own is important in creating learning environments that build on and engage with diversity.

In a preliminary stage of the research we asked eight third-year teacher education students to explore their own ethnic and classed identities. The complexities of identity are foregrounded in both the assumptions we made in selecting particular students for the project and in the ways they did (not) think about themselves as having ethnic or classed identities.

In this paper we draw on these findings to interrogate how categories of identity are fluid, shifting and ongoing processes of negotiation: troubling and complex. We also consider the implications for teacher education.

Surviving suppression : no detectable impacts of Class A foam on soil invertebrates and some Australian native plants

Firefighting foams (Class A foams) are an effective and widespread firefighting tool which are frequently used in environmentally sensitive areas. Firefighting foams are known to be ecologically damaging in aquatic environments, however their impacts at the plant species or ecosystem level are relatively unknown. Reports of shoot damage to plants, suppressed flowering, and changes in plant community composition suggested that the ecological damage caused by their use may be unacceptable. However, applications of foam to seedlings of some Australian plant species from representative and widespread families, showed no detectable impacts on a range of vegetative growth characteristics. Application of 1.0% foam to heathland soils showed no detectable impacts on soil invertebrate Orders sampled over several months. The results are encouraging for the continued use of Class A foam as a fire suppression technique.

Ethnicity, social class, practice and pedagogy : a study of teacher identity

This paper draws on findings from three separate research projects to illustrate how teachers’ and student-teachers’ ethnic and social class identities shape theirrepresentations of professional self, their interactions with their students and the pedagogies they privilege in their classes. The paper raises a number of important implications for teacher education seeking to prepare teachers for culturally diverse contexts such as Australian classrooms. It concludes that a major challenge for teacher educators is to find ways of enabling their students to interrogate often taken-for-granted assumptions about their own ethnic and classed positionings.

Dive behaviour, foraging locations and maternal-attendance patterns in Australian fur seals (Arctocephalus pusillus doriferus)

The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur seals (Arctocephalus pusillus doriferus) from Kanowna Island (39°10'S, 146°18'E) in Bass Strait, southeastern Australia, were determined throughout lactation during 1997–1999. Foraging-trip durations increased as lactation progressed, being shortest in summer (3.71 ± 0.24 days; mean ± 1 SE) and longest in winter (6.77 ± 0.57 days, P < 0.05), but maternal-attendance periods did not differ in duration (1.70 ± 0.10 days, P > 0.5). Individual mean attendance periods and trip durations were positively correlated (r² = 0.21, P < 0.005). Diving commenced shortly after seals left the colony (2.6 ± 0.4 h), was continuous for long periods (up to 36 h), occurred mostly during daylight hours, and lacked regular diel variation in depth. The majority of dives (78%) were typically U-shaped and reached depths corresponding to the prevailing depths in Bass Strait (65–85 m), indicating that these animals forage mostly on the benthos of the shallow continental shelf in this region. Such behaviour is unusual for fur seals but is reminiscent of that of some sea lion species. Mean dive durations varied between 2.0 and 3.7 min (maximum 8.9 min) and the theoretical aerobic dive limit (3.91–4.26 min) was exceeded on 17.3% of dives. Dive frequency (8.3 ± 0.6/h) and the proportion of time at sea spent diving (40.7 ± 2.1%) were weakly negatively related to the duration of the foraging trip (r²= 0.07, P < 0.004, and r² = 0.13, P < 0.0001, respectively). Data from at-sea locations showed that lactating females forage almost exclusively within Bass Strait during all seasons.

Experienced teachers' perspectives on cultural and social class diversity : which differences matter?

This article reports on a pilot study that investigated the beliefs, values, and pedagogies of experienced high school teachers who worked with student populations of non-English speaking and economically disadvantaged immigrants or refugees in Australia. Qualitative research methods, including focus groups and in-depth individual interviews with teachers, produced data that were examined using Critical Discourse Analysis. Close reading of the teachers' comments suggests that there are a number of key discourses that teachers use to make sense of differences among culturally diverse and economically disadvantaged groups of students. Specifically, teachers distinguish between cultural groups on the basis of students' life experiences prior to arrival in Australia; students' collective and individual educational experiences; and the different social class positioning of students within the same ethnic group. In their comments, teachers at times categorised students in generalised and stereotypical ways but also were able to critique and reflect on their personal assumptions. An analysis of the teachers' reflections provides insights into how they made sense of “diversity” and how, as teachers, they try to work productively with ethnically diverse and economically disadvantaged students.

The Australian class structure and Australian politics 1931 - 40

This paper presents the results of an analysis of the class structure of interwar Australia based largely on the 1933 Commonwealth census. It reviews previous analyses by academics but although contemporary journalists and political strategists. It develops an estimate of the class composition of the electorate as distinct from the general population and attempts to define the class position of voters outside of the paid workforce. It considers the question of to what extent Labor needed non-working-class votes to secure an electoral majority and how the differing social composition of the Australian states impacted on electoral outcomes and Labor strategies. It employs the method of bounds to develop some preliminary conclusions about the electoral behaviour of different social groups and concludes with some observations on the divided nature of the Australian working class and the competing strategies that parties developed in their search for an electoral majority.

Book review : Class act : Melbourne Workers Theatre 1987 - 2007

The article reviews the book "Class Act: Melbourne Workers Theatre 1987-2007," edited by Glenn D'Cruz.

A class of modified variable step-size NLMS algorithms for system identification

This paper proposes a class of modified variable step-size normalized least mean square (VS NLMS) algorithms. The class of schemes are obtained from estimating the optimum step-size of NLMS that minimizes the mean square deviation (MSD). During the estimation, we consider the properties of the additive noise and the input excitation together. The developed class of VS NLMS algorithms have simple forms and give improved tradeoff of fast convergence rate and low misadjustment in system identification.

Examination of EMG normalisation methods for the study of the posterior and posterolateral neck muscles in healthy controls

The purpose of this study was to examine the reliability of normalisation methods used in the study of the posterior and posterolateral neck muscles in a group of healthy controls. Six asymptomatic male subjects performed a total of 12 maximum voluntary isometric contractions (MVIC) and 60%-submaximal isometric contractions (60%-MVIC) against the torque arm of an isokinetic dynamometer whilst surface and intramuscular electromyography (EMG) was recorded unilaterally from representative posterior and posterolateral locations. Reliability was calculated using intra-class correlation coefficient (ICC), relative standard error of measurement (%SEM) and relative coefficient of variation (%CV). Maximal torque output was found to be highly reliable in the directions of extension and right lateral bending when the first of three MVIC contractions was excluded. When averaged across contraction direction, high reliability was found for both surface (MVIC: ICC = 0.986, %SEM = 7.5, %CV = 9.2; 60%-MVIC: ICC = 0.975, %SEM = 10, %CV = 13.7) and intramuscular (MVIC: ICC = 0.910, %SEM = 20, %CV = 19.1; 60%-MVIC: ICC = 0.952, %SEM = 16.5, %CV = 13.5) electrodes. Intramuscular electrodes displayed the least reliability in right lateral bending. The use of visual feedback markedly increased the reliability of 60%-MVIC contractions.

Adaptive fast finite time control of a class of uncertain nonlinear systems

This paper concerns the adaptive fast finite time control of a class of nonlinear uncertain systems of which the upper bounds of the system uncertainties are unknown. By using the fast non-smooth control Lyapunov function and the method of so-called adding a power integrator merging with adaptive technique, a recursive design procedure is provided, which guarantees the fast finite time stability of the closed-loop system. It is proved that the control input is bounded, and a simulation example is given to illustrate the effectiveness of the theoretical results.

An exploration of motives for attending Australian ecotourism locations and their influence on future intentions

This paper sought to explore the push [internal] motivations of eco-tourists and the influence of these motivational drives on their future ecotourism intentions. Findings from this exploratory study identified five key internal motivations, namely, 'self-esteem', 'relaxation', 'social interaction', 'self-fulfilment' and 'thrill and excitement'. Further analysis identified that 'self-esteem', elaxation' and 'self-fulfilment' motives were significantly related to ecotourist's intention to volunteer as well as their intention to donate money to an eco-tourism destination. Additionally, 'self-fulfilment' and 'thrill and excitement' motives were identified as impacting upon eco-tourists’ future attendance intentions. Consequently, findings from this research provide eco-tourism operators with insight into eco-tourist motivations to inform product and brand development and promotional activities and assist in the ongoing development effective eco-tourist retention strategies.