Characterisation of a cell wall-anchored protein of Staphylococcus saprophyticus associated with linoleic acid resistance

The Gram-positive bacterium Staphylococcus saprophyticus is the second most frequent causative agent of community-acquired urinary tract infections (UTI), accounting for up to 20% of cases. A common feature of staphylococci is colonisation of the human skin. This involves survival against innate immune defenses including antibacterial unsaturated free fatty acids such as linoleic acid which act by disrupting bacterial cell membranes. Indeed, S. saprophyticus UTI is usually preceded by perineal skin colonisation.

Supporting collaboration on very large-scale interactive wall surfaces

In this paper we describe CubIT, a multi-user presentation and collaboration system installed at the Queensland University of Technology’s (QUT) Cube facility. The ‘Cube’ is an interactive visualisation facility made up of five very large-scale interactive multi-panel wall displays, each consisting of up to twelve 55-inch multi-touch screens (48 screens in total) and massive projected display screens situated above the display panels. The paper outlines the unique design challenges, features, implementation and evaluation of CubIT. The system was built to make the Cube facility accessible to QUT’s academic and student population. CubIT enables users to easily upload and share their own media content, and allows multiple users to simultaneously interact with the Cube’s wall displays. The features of CubIT were implemented via three user interfaces, a multi-touch interface working on the wall displays, a mobile phone and tablet application and a web-based content management system. Each of these interfaces plays a different role and offers different interaction mechanisms. Together they support a wide range of collaborative features including multi-user shared workspaces, drag and drop upload and sharing between users, session management and dynamic state control between different parts of the system. The results of our evaluation study showed that CubIT was successfully used for a variety of tasks, and highlighted challenges with regards to user expectations regarding functionality as well as issues arising from public use.

Characterization of the tail-specific protease (Tsp) from Legionella

Bacterial tail-specific proteases (Tsps) have been attributed a wide variety of functions including intracellular virulence, cell wall morphology, proteolytic signal cascades and stress response. This study tested the hypothesis that Tsp has a key function for the transmissive form of Legionella pneumophila. A tsp mutant was generated in Legionella pneumophila 130b and the characteristics of this strain and the isogenic wild-type were examined using a range of growth and proteomic analyses. Recombinant Tsp protein was also produced and analyzed. The L. pneumophila tsp mutant showed no defect in growth on rich media or during thermo-osmotic stress conditions. In addition, no defects in cellular morphology were observed when the cells were examined using transmission electron microscopy. Purified recombinant Tsp was found to be an active protease with a narrow substrate range. Proteome analysis using iTRAQ (5% coverage of the proteome) found that, of those proteins detected, only 5 had different levels in the tsp mutant compared to the wild type. ACP (Acyl Carrier Protein), which has a key role for Legionella differentiation to the infectious form, was reduced in the tsp mutant; however, tsp(-) was able to infect and replicate inside macrophages to the same extent as the wild type. Combined, these data demonstrate that Tsp is a protease but is not essential for Legionella growth or cell infection. Thus, Tsp may have functional redundancy in Legionella.

Development of realistic design fire time-temperature curves for the testing of cold-formed steel wall system

Fire resistance rating of light gauge steel frame (LSF) wall systems is obtained from fire tests based on the standard fire time-temperature curve. However, fire severity has increased in modern buildings due to higher fuel loads as a result of modern furniture and light weight constructions that make use of thermoplastics materials, synthetic foams and fabrics. Some of these materials are high in calorific values and increase both the spread of fire growth and heat release rate, thus increasing the fire severity beyond that of the standard fire curve. Further, the standard fire curve does not include a decay phase that is present in natural fires. Despite the increasing usage of LSF walls, their behaviour in real building fires is not fully understood. This paper presents the details of a research study aimed at developing realistic design fire curves for use in the fire tests of LSF walls. It includes a review of the characteristics of building fires, previously developed fire time-temperature curves, computer models and available parametric equations. The paper highlights that real building fire time-temperature curves depend on the fuel load representing the combustible building contents, ventilation openings and thermal properties of wall lining materials, and provides suitable values of many required parameters including fuel loads in residential buildings. Finally, realistic design fire time-temperature curves simulating the fire conditions in modern residential buildings are proposed for the testing of LSF walls.

Natural convection due to differential heating of inclined walls and heat source placed on bottom wall of an attic shaped space

Numerical investigation of free convection heat transfer in an attic shaped enclosure with differentially heated two inclined walls and filled with air is performed in this study. The left inclined surface is uniformly heated whereas the right inclined surface is uniformly cooled. There is a heat source placed on the right side of the bottom surface. Rest of the bottom surface is kept as adiabatic. Finite volume based commercial software ANSYS 15 (Fluent) is used to solve the governing equations. Dependency of various flow parameters of fluid flow and heat transfer is analyzed including Rayleigh number, Ra ranging from 103 to 106, heater size from 0.2 to 0.6, heater position from 0.3 to 0.7 and aspect ratio from 0.2 to 1.0 with a fixed Prandtl number of 0.72. Outcomes have been reported in terms of temperature and stream function contours and local Nusselt number for various Ra, heater size, heater position, and aspect ratio. Grid sensitivity analysis is performed and numerically obtained results have been compared with those results available in the literature and found good agreement.

Effect of cell wall properties on porosity and shrinkage of dried apple

Water removal during drying depends on the pathway of water migration from food materials. Moreover, the water removal rate also depends on the characteristics of the cell wall of plant tissue. In this study, the influence of cell wall properties (such as moisture distribution, stiffness, thickness and cell dimension) on porosity and shrinkage of dried product was investigated. Cell wall stiffness depends on a complex combination of plant cell microstructure, composition of food materials and the water-holding capacity of the cell. In this work, a preliminary investigation of the cell wall properties of apple was conducted in order to predict changes of porosity and shrinkage during drying. Cell wall characteristics of two types of apple (Granny Smith and Red Delicious) were investigated under convective drying to correlate with porosity and shrinkage. A scanning electron microscope (SEM), 2kN Intron, pycnometer and ImageJ software were used in order to measure and analyse cell characteristics, water holding capacity of cell walls, porosity and shrinkage. The cell firmness of the Red Delicious apple was found to be higher than for Granny Smith apples. A remarkable relationship was observed between cell wall characteristics when compare with heat and mass transfer characteristics. It was also found that the evolution of porosity and shrinkage are noticeably influenced by the nature of the cell wall during convective drying. This study has revealed a better understanding of porosity and the shrinkage of dried food at microscopy (cell) level, and will provide better insights to attain energy-effective drying processes and improved quality of dried foods.

Matter and movement: Expression as topological continuity or a return to Butades' wall

This paper aims to address the ways in which drawing can be understood as the becoming-expressive of materials, site, and body, over time. The discussion pivots around a series of studies that replace linear or causal relationships – in history, drawing and expression – with topological movement. My approach is largely through a speculative case study. In a rereading of the familiar Butades myth, I examine how a shadow tracing can variously be taken as the first mimetic art with its origins in the urge to “capture”, and, antithetically, as the originary expressive folding of matter, site and body. The paper is divided into five sections. The first presents the Butades myth, identifying the representational problem that lies at the roots of its traditional telling. The next three sections outline a series of topologies that facilitate a discussion of the Butades myth from historical, disciplinary, and expressive perspectives. The final section aims to show the relevance of this discussion to a contemporary drawing practice, using my own drawing research as a case study. The field of inquiry is that of representational critique. The fold, an image associated with a topological geometry, replaces the relational or signifying disjuncture of representational structures, and suggests a becoming- expressive of subject and object, form and matter.

Will the TPP feed consumers to the wolves of Wall Street?

In the wake of the global financial crisis, there’s been a push by policy-makers for greater regulation of banks, financial institutions and the “wolves of Wall Street”. This was accompanied by a highly visible Occupy Wall Street movement, demanding political and legal reform. But could new trade agreements undermine consumer protection?

Design of steel roof and wall cladding systems for pull-out failures

When thin steel roof and wall cladding systems are subjected to wind uplift/suction forces, local pull-through or pull-out failures occur prematurely at their screwed connections. During high wind events such as stom1s and cyclones, these localized failures then lead to severe damage to buildings and their contents. In recent times, the use of thin steel battens, purlins and girts has increased considerably, which has made the pull-out failures more critical in the design of steel cladding systems. An experimental investigation was therefore carried out to study the pull-out failure using both static and cyclic tests for a range of commonly used screw fasteners and steel battens, purlins and girts. This paper presents the details ofthis experimental investigation and its results.

Numerical modelling and design of unlined cold-formed steel wall frames

Cold-formed steel wall frame systems using lipped or unlipped C-sections and gypsum plasterboard lining are commonly utilised in the construction of both the load bearing and non-load bearing walls in the residential, commercial and industrial buildings. However, the structural behaviour of unlined and lined stud wall frames is not well understood and adequate design rules are not available. A detailed research program was therefore undertaken to investigate the behaviour of stud wall frame systems. As the first step in this research, the problem relating to the degree of end fixity of stud was investigated. The studs are usually connected to the top and bottom tracks and the degree of end fixity provided by these tracks is not adequately addressed by the design codes. A finite element model of unlined frames was therefore developed, and validated using full scale experimental results. It was then used in a detailed parametric study to develop appropriate design rules for unlined wall frames. This study has shown that by using appropriate effective length factors, the ultimate load and failure modes of the unlined studs can be accurately predicted using the provisions of Australian or American cold-formed steel structures design codes. This paper presents the details of the finite element analyses, the results and recommended design rules for unlined wall frames.

The role of tunnel junction resistances and defects on electron transport mechanism in networks of two-dimensional disordered conductors

The effect of tunnel junction resistances on the electronic property and the magneto-resistance of few-layer graphene sheet networks is investigated. By decreasing the tunnel junction resistances, transition from strong localization to weak localization occurs and magneto-resistance changes from positive to negative. It is shown that the positive magneto-resistance is due to Zeeman splitting of the electronic states at the Fermi level as it changes with the bias voltage. As the tunnel junction resistances decrease, the network resistance is well described by 2D weak localization model. Sensitivity of the magneto-resistance to the bias voltage becomes negligible and diminishes with increasing temperature. It is shown 2D weak localization effect mainly occurs inside of the few-layer graphene sheets and the minimum temperature of 5 K in our experiments is not sufficiently low to allow us to observe 2D weak localization effect of the networks as it occurs in 2D disordered metal films. Furthermore, defects inside the few-layer graphene sheets have negligible effect on the resistance of the networks which have small tunnel junction resistances between few-layer graphene sheets

Climbing skill and complexity of climbing wall design: Assessment of jerk as a novel indicator of performance fluency

This study investigated a new performance indicator to assess climbing fluency (smoothness of the hip trajectory and orientation of a climber using normalized jerk coefficients) to explore effects of practice and hold design on performance. Eight experienced climbers completed four repetitions of two, 10-m high routes with similar difficulty levels, but varying in hold graspability (holds with one edge vs holds with two edges). An inertial measurement unit was attached to the hips of each climber to collect 3D acceleration and 3D orientation data to compute jerk coefficients. Results showed high correlations (r = .99, P < .05) between the normalized jerk coefficient of hip trajectory and orientation. Results showed higher normalized jerk coefficients for the route with two graspable edges, perhaps due to more complex route finding and action regulation behaviors. This effect decreased with practice. Jerk coefficient of hip trajectory and orientation could be a useful indicator of climbing fluency for coaches as its computation takes into account both spatial and temporal parameters (ie, changes in both climbing trajectory and time to travel this trajectory)