On equilibrium states and dust charging in dusty plasmas

The dust-charge variation process is revisited, accounting for the background density variation associated with electron capture and release by the dust grains. It appears possible to maintain overall charge neutrality in the plasma without any external particle source or sink. It is shown that if the dust charge and density are sufficiently high, the effect of the background electron density variation on dust-charge relaxation is important. The equilibrium dust charge and its rate of variation are obtained for dusty plasmas subject to strong UV irradiation. The latter releases photoelectrons from the dust surface and can significantly affect the equilibrium dust charge, its variation rate, as well as the overall charge neutrality in the plasma.

Keyword field-free conjunctive keyword searches on encrypted data and extension for dynamic groups

We consider the following problem: a user stores encrypted documents on an untrusted server, and wishes to retrieve all documents containing some keywords without any loss of data confidentiality. Conjunctive keyword searches on encrypted data have been studied by numerous researchers over the past few years, and all existing schemes use keyword fields as compulsory information. This however is impractical for many applications. In this paper, we propose a scheme of keyword field-free conjunctive keyword searches on encrypted data, which affirmatively answers an open problem asked by Golle et al. at ACNS 2004. Furthermore, the proposed scheme is extended to the dynamic group setting. Security analysis of our constructions is given in the paper.

The outsourcing of accounting services and the subsequent accounting education implications

This paper examines the outsourcing of accounting services by Australian accounting firms. It considers what, if any, impact the outsourcing of accounting services may have on accounting graduates if entry level tasks normally completed by graduates are sent to offshore processing centres. This paper categorises the most important prerequisite skills requirements of new junior employees identified by accounting firms in Australia.

Plasma Enabled Fabrication of Silicon Carbide Nanostructures

Silicon carbide is one of the promising materials for the fabrication of various one- and two-dimensional nanostructures. In this chapter, we discuss experimental and theoretical studies of the plasma-enabled fabrication of silicon carbide quantum dots, nanowires, and nanorods. The discussed fabrication methods include plasma-assisted growth with and without anodic aluminium oxide membranes and with or without silane as a source of silicon. In the silane-free experiments, quartz was used as a source of silicon to synthesize the silicon carbide nanostructures in an environmentally friendly process. The mechanism of the formation of nanowires and nanorods is also discussed.

Becoming an inclusive educator : applying Deleuze & Guattari to teacher education

New ways of thinking are required in teacher education to promote beginning teachers as change agents in education. Twenty years after the Salamanca Statement (UNESCO, 1994) that called for schools to provide equitable opportunities for all children, teaching practices in many classrooms are informed by the deficit view of learning. Beginning teachers need to be prepared to challenge the ideological influences that operate in schools. Deleuze and Guattari’s (1987) model of the rhizome is used to report one beginning teacher’s journey as she learnt to negotiate structural and personal obstacles to create an inclusive learning environment. Data from reflective diaries, semi-structured interviews and classroom observations highlight contextual and personal factors in one case study that contributed to the nonlinear, complex process of becoming an inclusive educator. The paper concludes by arguing the voice of beginning teachers is essential for the ongoing movement towards the creation of just, inclusive schools.

UafB is a serine-rich repeat adhesin of Staphylococcus saprophyticus that mediates binding to fibronectin, fibrinogen and human uroepithelial cells

Staphylococcus saprophyticus is an important cause of urinary tract infection (UTI), particularly among young women, and is second only to uropathogenic Escherichia coli as the most frequent cause of UTI. The molecular mechanisms of urinary tract colonization by S. saprophyticus remain poorly understood. We have identified a novel 6.84 kb plasmid-located adhesin-encoding gene in S. saprophyticus strain MS1146 which we have termed uro-adherence factor B (uafB). UafB is a glycosylated serine-rich repeat protein that is expressed on the surface of S. saprophyticus MS1146. UafB also functions as a major cell surface hydrophobicity factor. To characterize the role of UafB we generated an isogenic uafB mutant in S. saprophyticus MS1146 by interruption with a group II intron. The uafB mutant had a significantly reduced ability to bind to fibronectin and fibrinogen. Furthermore, we show that a recombinant protein containing the putative binding domain of UafB binds specifically to fibronectin and fibrinogen. UafB was not involved in adhesion in a mouse model of UTI; however, we observed a striking UafB-mediated adhesion phenotype to human uroepithelial cells. We have also identified genes homologous to uafB in other staphylococci which, like uafB, appear to be located on transposable elements. Thus, our data indicate that UafB is a novel adhesin of S. saprophyticus that contributes to cell surface hydrophobicity, mediates adhesion to fibronectin and fibrinogen, and exhibits tropism for human uroepithelial cells.

Autotransporters of Escherichia coli : a sequence-based characterization

Autotransporter (AT) proteins are found in all Escherichia coli pathotypes and are often associated with virulence. In this study we took advantage of the large number of available E. coli genome sequences to perform an in-depth bioinformatic analysis of AT-encoding genes. Twenty-eight E. coli genome sequences were probed using an iterative approach, which revealed a total of 215 AT-encoding sequences that represented three major groups of distinct domain architecture: (i) serine protease AT proteins, (ii) trimeric AT adhesins and (iii) AIDA-I-type AT proteins. A number of subgroups were identified within each broad category, and most subgroups contained at least one characterized AT protein; however, seven subgroups contained no previously described proteins. The AIDA-I-type AT proteins represented the largest and most diverse group, with up to 16 subgroups identified from sequence-based comparisons. Nine of the AIDA-I-type AT protein subgroups contained at least one protein that possessed functional properties associated with aggregation and/or biofilm formation, suggesting a high degree of redundancy for this phenotype. The Ag43, YfaL/EhaC, EhaB/UpaC and UpaG subgroups were found in nearly all E. coli strains. Among the remaining subgroups, there was a tendency for AT proteins to be associated with individual E. coli pathotypes, suggesting that they contribute to tissue tropism or symptoms specific to different disease outcomes.

Demonstration of regulatory cross-talk between P fimbriae and type 1 fimbriae in uropathogenic Escherichia coli

The majority of Escherichia coli strains isolated from urinary tract infections have the potential to express multiple fimbriae. Two of the most common fimbrial adhesins are type 1 fimbriae and pyelonephritis-associated pili (Pap). Previous research has shown that induced, plasmid-based expression of a Pap regulator, papB, and its close homologues can prevent inversion of the fim switch controlling the expression of type 1 fimbriae. The aim of the present study was to determine if this cross-regulation occurs when PapB is expressed from its native promoter in the chromosome of E. coli K-12 and clinical isolates. The regulation was examined in three ways: (1) mutated alleles of the pap regulatory region, including papB and papI, that maintain the pap promoter in either the off or the on phase were exchanged into the chromosome of both E. coli K-12 and the clinical isolate E. coli CFT073, and the effect on type 1 fimbrial expression was measured; (2) type 1 fimbrial expression was determined using a novel fimS : : gfp+ reporter system in mutants of the clinical isolate E. coli 536 in which combinations of complete fimbrial clusters had been deleted; (3) type 1 fimbrial expression was determined in a range of clinical isolates and compared with both the number of P clusters and their expression. All three approaches demonstrated that P expression represses type 1 fimbrial expression. Using a number of novel genetic approaches, this work extends the initial finding that PapB inhibits FimB recombination to the impact of this regulation in clinical isolates.

Comparative analysis of FimB and FimE recombinase activity

FimB and FimE are site-specific recombinases, part of the λ integrase family, and invert a 314 bp DNA switch that controls the expression of type 1 fimbriae in Escherichia coli. FimB and FimE differ in their activity towards the fim switch, with FimB catalysing inversion in both directions in comparison to the higher-frequency but unidirectional on-to-off recombination catalysed by FimE. Previous work has demonstrated that FimB, but not FimE, recombination is completely inhibited in vitro and in vivo by a regulator, PapB, expressed from a distinct fimbrial locus. The aim of this work was to investigate differences between FimB and FimE activity by exploiting the differential inhibition demonstrated by PapB. The research focused on genetic changes to the fim switch that alter recombinase binding and its structural context. FimB and FimE still recombined a switch in which the majority of fimS DNA was replaced with a larger region of non-fim DNA. This demonstrated a minimal requirement for FimB and FimE recombination of the Fim binding sites and associated inverted repeats. With the original leucine-responsive regulatory protein (Lrp) and integration host factor (IHF)-dependent structure removed, PapB was now able to inhibit both recombinases. The relative affinities of FimB and FimE were determined for the four ‘half sites’. This analysis, along with the effect of extensive swaps and duplications of the half sites on recombination frequency, demonstrated that FimB recruitment and therefore subsequent activity was dependent on a single half site and its context, whereas FimE recombination was less stringent, being able to interact initially with two half sites with equally high affinity. While increasing FimB recombination frequencies failed to overcome PapB repression, mutations made in recombinase binding sites resulted in inhibition of FimE recombination by PapB. Overall, the data support a model in which the recombinases differ in loading order and co-operative interactions. PapB exploits this difference and FimE becomes susceptible when its normal loading is restricted or changed.

Rethinking OHS Enforcement

The authors confront the challenges facing OHS regulators and stakeholders in a new and different world dominated by service industries and globalisation rather than manufacturing industries and protection. They explore new models of OHS regulation that take account of gaps and deficiencies in the current arrangements.

Mind the insolvency gap : lessons to be learned from audit expectations gap theory

There is a general perception that public confidence in the insolvency profession is low as the result of the recent unethical practices of a few high profile liquidators. As a result, the effectiveness of the current regulatory mechanisms has been questioned, leading to a review of the performance of insolvency practitioners and subsequent regulation proposals. The challenge for the insolvency profession is balancing the expectations of the general public whilst ensuring that the obligations and duties imposed upon them are performed to acceptable and realistic standards. It is difficult (if not impossible) for the profession to meet this challenge in the absence of a cohesive framework which identifies those issues that require further regulation as opposed to those that relate to general education on the insolvency process. This paper will examine the audit expectations gap theory in the context of insolvency practitioners and suggests that a model based on this theory provides an effective framework for evaluating the regulation of the insolvency industry.

Performance characterisation of a stormwater treatment bioretention basin

Treatment performance of bioretention basins closely depends on hydrologic and hydraulic factors such as rainfall characteristics and inflow and outflow discharges. An in-depth understanding of the influence of these factors on water quality treatment performance can provide important guidance for effective bioretention basin design. In this paper, hydraulic and hydrologic factors impacting pollutant removal by a bioretention basin were assessed under field conditions. Outcomes of the study confirmed that the antecedent dry period plays an important role in influencing treatment performance. A relatively long antecedent dry period reduces nitrite and ammonium concentrations while increasing the nitrate concentration, which confirms that nitrification occurs within the bioretention basin. Additionally, pollutant leaching influences bioretention basin treatment performance, reducing the nutrients removal efficiency, which was lower for high rainfall events. These outcomes will contribute to a greater understanding of the treatment performance of bioretention basins, assisting in the design, operation and maintenance of these systems.

Dual-functional gum arabic binder for silicon anodes in lithium ion batteries

Si has attracted enormous research and manufacturing attention as an anode material for lithium ion batteries (LIBs) because of its high specific capacity. The lack of a low cost and effective mechanism to prevent the pulverization of Si electrodes during the lithiation/ delithiation process has been a major barrier in the mass production of Si anodes. Naturally abundant gum arabic (GA), composed of polysaccharides and glycoproteins, is applied as a dualfunction binder to address this dilemma. Firstly, the hydroxyl groups of the polysaccharide in GA are crucial in ensuring strong binding to Si. Secondly, similar to the function of fiber in fiberreinforced concrete (FRC), the long chain glycoproteins provide further mechanical tolerance to dramatic volume expansion by Si nanoparticles. The resultant Si anodes present an outstanding capacity of ca. 2000 mAh/g at a 1 C rate and 1000 mAh/g at 2 C rate, respectively, throughout 500 cycles. Excellent long-term stability is demonstrated by the maintenance of 1000 mAh/g specific capacity at 1 C rate for over 1000 cycles. This low cost, naturally abundant and environmentally benign polymer is a promising binder for LIBs in the future.