Comparison of new <i>in situ </i>root-reinforcement measuring devices to existing techniques

Mechanical root-reinforcement is difficult to quantify. Existing in-situ methods are cumbersome, while modelling requires parameters which are difficult to acquire. In this paper, two new in-situ measurement devices are introduced ('cork screw' and 'pin vane') and their performance is compared to field vane and laboratory direct shear strength measurements in fallow and rooted soil. Both new methods show a close correlation with field vane readings in fallow soil. Tests in reinforced soil show that both new methods can be installed without significant root disturbance. The simplicity of both new methods allows for practical in-situ use and both can be used to study soil stress-strain behaviour, thus addressing some major limitations in existing methodologies for characterising rooted soil.</p

Effect of root spacing on interpretation of blade penetration tests-full-scale physical modelling

The spatial distribution of plant roots is an important parameter when the stability of vegetated slopes is to be assessed. Previous studies in both laboratory and field conditions have shown that a penetrometer adapted with a blade-shaped tip can be used to detect roots from sudden drops in penetrometer resistance. Such drops can be related to root properties including diameter, stiffness and strength using simpleWinkler foundation models, thereby providing a field instrument for rapid quantification of root properties and distribution. While this approach has proved useful for measuring single widely-spaced roots, it has not previously been determined how the penetrometer response changes as a result of roots being in close proximity. Therefore in this study 1-g physical modelling (at 1:1 scale) was conducted to study the effect of vertical root spacing using horizontal, straight 3D-printed root analogues. Results showthatwhen roots are closely spaced, there is significant interaction between them, resulting in higher apparent root displacements to failure and an increased amount of energy being dissipated. This preliminary work shows that the interpretive models used to analyse the penetrometer trace require further development to account for root-soil-root interactions in densely rooted soil.</p

Evaluation of X-ray/EUV Nanolithography Facility at AS Through Wavefront Propagation Simulations

Synchrotron light sources can provide the required spatial coherence, stability and control that is required to support the development of advanced lithography at the extreme ultraviolet and soft X-ray wavelengths that are relevant to current and future fabricating technologies. Here we present an evaluation of the optical performance of the soft X-ray (SXR) beamline of the Australian Synchrotron (AS) and its suitability for developing interference lithography using radiation in the 91.8 eV (13.5 nm) to 300 eV (4.13 nm) range. A comprehensive physical optics model of the APPLE-II undulator source and SXR beamline was constructed to simulate the properties of the illumination at the proposed location of a photomask, as a function of photon energy, collimation, and monochromator parameters. The model is validated using a combination of experimental measurements of the photon intensity distribution of the undulator harmonics. We show that the undulator harmonics intensity ratio can be accurately measured using an imaging detector and controlled using beamline optics. Finally, we evaluate photomask geometric constraints and achievable performance for the limiting case of fully spatially coherent illumination.Comment: 21 pages, 7 figures, 3 tables. Preprint: submitted to Journal of Synchrotron Radiation 16/11/2

Line Graphs of Weighted Networks for Overlapping Communities

In this paper, we develop the idea to partition the edges of a weighted graph in order to uncover overlapping communities of its nodes. Our approach is based on the construction of different types of weighted line graphs, i.e. graphs whose nodes are the links of the original graph, that encapsulate differently the relations between the edges. Weighted line graphs are argued to provide an alternative, valuable representation of the system's topology, and are shown to have important applications in community detection, as the usual node partition of a line graph naturally leads to an edge partition of the original graph. This identification allows us to use traditional partitioning methods in order to address the long-standing problem of the detection of overlapping communities. We apply it to the analysis of different social and geographical networks.Comment: 8 Pages. New title and text revisions to emphasise differences from earlier paper

Vulnerability of low-arsenic aquifers to municipal pumping in Bangladesh

Sandy aquifers deposited >12,000 years ago, some as shallow as 30 m, have provided a reliable supply of low-arsenic (As) drinking water in rural Bangladesh. This study concerns the potential risk of contaminating these aquifers in areas surrounding the city of Dhaka where hydraulic heads in aquifers >150 m deep have dropped by 70 m in a few decades due to municipal pumping. Water levels measured continuously from 2012 to 2014 in 12 deep (>150 m), 3 intermediate (90-150 m) and 6 shallow (<90 m) community wells, 1 shallow private well, and 1 river piezometer show that the resulting drawdown cone extends 15-35 km east of Dhaka. Water levels in 4 low-As community wells within the 62-147 m depth range closest to Dhaka were inaccessible by suction for up to a third of the year. Lateral hydraulic gradients in the deep aquifer system ranged from 1.7 × 10-4 to 3.7 × 10-4 indicating flow towards Dhaka throughout 2012-2014. Vertical recharge on the edge of the drawdown cone was estimated at 0.21 ± 0.06 m/yr. The data suggest that continued municipal pumping in Dhaka could eventually contaminate some relatively shallow community wells

Utopian Archives, Decolonial Affordances: Introduction to Special Issue

Colonial archives constituted a technology that enabled the collection, storage, ordering, retrieval and exchange of knowledge as an instrument of colonial governance. It is not surprising that when such archives were inherited by independent nation-states they were not given the authority previously granted them and have often been neglected. What, then, is the future of colonial archives in postcolonial nations? How should we rethink these archives in relation to decolonial futures? This essay introduces a collection of articles that explore the repertoires of action latent in archives and how colonial archives are being reconfigured to imagine decolonial futures