Perpendicular-to-grain compression behaviour of screw reinforced timber and a novel application of digital image correlation

This project investigates various factors which influence the behaviour of a timber roof structure designed by Smith & Wallwork Engineers. The first part of the project focused on material of sweet chestnut, where Digital Image Correlation (DIC) was employed to obtain values for the shear modulus. DIC was able to implement the shear field test method prescribed in BS EN 408:2010, along with two new methods developed based on additional information available through DIC. These methods were accurate, fast to implement, and potentially more robust than the shear field test method. A method to estimate the true value of the Timoshenko shear coefficient was also developed. The second section of the project involved physical testing of portions of the roof structure to investigate the behaviour of screw-reinforced and unreinforced timber loaded perpendicular to grain. Together with finite element modelling, it was noticed that a key aspect of the connection's behaviour was the axial force transfer between overlapping screws via shear in the timber, and the resulting relative displacement between the screws. A simple spring model was developed to characterise the compression stiffness of the roof which can now be used in reverse to calculate the forces due to moisture expansion or contraction

Multi-scale hydro-morphodynamic modelling using mesh movement methods

Abstract: Hydro-morphodynamic modelling is an important tool that can be used in the protection of coastal zones. The models can be required to resolve spatial scales ranging from sub-metre to hundreds of kilometres and are computationally expensive. In this work, we apply mesh movement methods to a depth-averaged hydro-morphodynamic model for the first time, in order to tackle both these issues. Mesh movement methods are particularly well-suited to coastal problems as they allow the mesh to move in response to evolving flow and morphology structures. This new capability is demonstrated using test cases that exhibit complex evolving bathymetries and have moving wet-dry interfaces. In order to be able to simulate sediment transport in wet-dry domains, a new conservative discretisation approach has been developed as part of this work, as well as a sediment slide mechanism. For all test cases, we demonstrate how mesh movement methods can be used to reduce discretisation error and computational cost. We also show that the optimum parameter choices in the mesh movement monitor functions are fairly predictable based upon the physical characteristics of the test case, facilitating the use of mesh movement methods on further problems

Identification of multiple root disease resistant wheat germplasm against cereal nematodes and dryland root rot and their validation in regions of economic importance

História da literatura portuguesa coordenada por Giulia Lanciani - primeiras páginas de um total pp. 7-108)História literária do século XVIII portuguêsGoverno de Portuga

Reliability of measuring abductor hallucis muscle parameters using two different diagnostic ultrasound machines

<p>Abstract</p> <p>Background</p> <p>Diagnostic ultrasound provides a method of analysing soft tissue structures of the musculoskeletal system effectively and reliably. The aim of this study was to evaluate within and between session reliability of measuring muscle dorso-plantar thickness, medio-lateral length and cross-sectional area, of the abductor hallucis muscle using two different ultrasound machines, a higher end Philips HD11 Ultrasound machine and clinically orientated Chison 8300 Deluxe Digital Portable Ultrasound System.</p> <p>Methods</p> <p>The abductor hallucis muscle of both the left and right feet of thirty asymptomatic participants was imaged and then measured using both ultrasound machines. Interclass correlation coefficients (ICC) with 95% confidence intervals (CI) were used to calculate both within and between session intra-tester reliability. Standard error of the measurement (SEM) calculations were undertaken to assess difference between the actual measured score across trials and the smallest real difference (SRD) was calculated from the SEM to indicate the degree of change that would exceed the expected trial to trial variability.</p> <p>Results</p> <p>The ICCs, SEM and SRD for dorso-plantar thickness and medial-lateral length were shown to have excellent to high within and between-session reliability for both ultrasound machines. The between-session reliability indices for cross-sectional area were acceptable for both ultrasound machines.</p> <p>Conclusion</p> <p>The results of the current study suggest that regardless of the type ultrasound machine, intra-tester reliability for the measurement the abductor hallucis muscle parameters is very high.</p

Fungicide resistance management in Australian grain crops

Fungicide resistance is a serious and increasing problem in cropping systems worldwide. Fungicides are an important component of integrated disease management strategies for the protection of crops from the impacts of fungal diseases. However, as their use has increased, the effectiveness of some fungicides has been reduced by the development of fungicide resistant pathogen populations. Without intervention, more fungicides are likely to become ineffective

Movement of environmental threats modifies the relevance of the defensive eye-blink in a spatially-tuned manner.

Subcortical reflexive motor responses are under continuous cortical control to produce the most effective behaviour. For example, the excitability of brainstem circuitry subserving the defensive hand-blink reflex (HBR), a response elicited by intense somatosensory stimuli to the wrist, depends on a number of properties of the eliciting stimulus. These include face-hand proximity, which has allowed the description of an HBR response field around the face (commonly referred to as a defensive peripersonal space, DPPS), as well as stimulus movement and probability of stimulus occurrence. However, the effect of stimulus-independent movements of objects in the environment has not been explored. Here we used virtual reality to test whether and how the HBR-derived DPPS is affected by the presence and movement of threatening objects in the environment. In two experiments conducted on 40 healthy volunteers, we observed that threatening arrows flying towards the participant result in DPPS expansion, an effect directionally-tuned towards the source of the arrows. These results indicate that the excitability of brainstem circuitry subserving the HBR is continuously adjusted, taking into account the movement of environmental objects. Such adjustments fit in a framework where the relevance of defensive actions is continually evaluated, to maximise their survival value

Ultrasound evaluation of the abductor hallucis muscle: Reliability study

© 2008 Cameron et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens