Which outcome expectancies are important in determining young adults intentions to use condoms with casual sexual partners?: A cross-sectional study

Background: The prevalence of unwanted pregnancy and sexually transmitted infection amongst young adults represents an important public health problem in the UK. Individuals attitude towards the use of condoms has been identified as an important determinant of behavioural intentions and action. The Theory of Planned Behaviour has been widely used to explain and predict health behaviour. This posits that the degree to which an individual positively or negatively values a behaviour (termed direct attitude) is based upon consideration of the likelihood of a number of outcomes occurring (outcome expectancy) weighted by the perceived desirability of those outcomes (outcome evaluation). Outcome expectancy and outcome evaluation when multiplied form indirect attitude. The study aimed to assess whether positive outcome expectancies of unprotected sex were more important for young adults with lower safe sex intentions, than those with safer sex intentions, and to isolate optimal outcomes for targeting through health promotion campaigns. Methods: A cross-sectional survey design was used. Data was collected from 1051 school and university students aged 16-24 years. Measures of intention, direct attitude and indirect attitude were taken. Participants were asked to select outcome expectancies which were most important in determining whether they would use condoms with casual sexual partners. Results: People with lower safe sex intentions were more likely than those with safer sex intentions to select all positive outcome expectancies for unprotected sex as salient, and less likely to select all negative outcome expectancies as salient. Outcome expectancies for which the greatest proportion of participants in the less safe sex group held an unfavourable position were: showing that I am a caring person, making sexual experiences less enjoyable, and protecting against pregnancy. Conclusions: The findings point to ways in which the attitudes of those with less safe sex intentions could be altered in order to motivate positive behavioural change. They suggest that it would be advantageous to highlight the potential for condom use to demonstrate a caring attitude, to challenge the potential for protected sex to reduce sexual pleasure, and to target young adults risk appraisals for pregnancy as a consequence of unprotected sex with casual sexual partners

Fabric sensors – modelling deformation in knitted fabrics

Fabric sensors are made from knitted conductive yarn and can be used to measure extension in wearable technologies and composite structures. Wearable technologies have considerable potential in sport and medical applications, for example recording limb movement in injury monitoring or sporting technique analysis. The electrical resistance through the fabric varies with extension due to the change in contact area and contact force between yarns. The resistance can be interpreted using correlations with displacement to calculate the deformation experienced by the fabric sensor. This paper describes a study which works towards a realistic digital model of a single jersey knitted fabric sensor by considering a non-idealised monofilament yarn of varied cross-section in a dense knit geometry. Models are created using TexGen, software developed at the University of Nottingham, taking advantage of its facility to create complex cross-sections which vary along the length of the yarn. Subsequent finite element analysis using ABAQUS with small representative volume elements and periodic boundary conditions showed high peak stresses at the boundaries, possibly caused by the contact surface being split across the boundary. Subsequent simulations using larger numbers of stitches and with relaxed boundary conditions in the x-direction showed more realistic deformations including reduction in width and curling of the material, reducing the impact of the boundaries on the overall fabric simulation, but with significant computational cost. The results give an initial assessment of deformations and contact pressures, which will aid understanding of the non-linear response found in mechanical testing and improve knowledge of how the inter-yarn contact varies. This work lays the foundation for further work which will aim to improve the similarity between the digital knit geometry and the physical sample, model larger areas of knitted fabric, include residual stresses from manufacture and use a multifilament yarn model. Subsequently the much more complex knitting patterns produced by the manufacturer of these sensors will then be able to be modelled

Efficient meshing technique for textile composites unit cells of arbitrary complexity

Meso-scale unit cell models are often used to simulate mechanical behaviour of textile composites. Apart from reliable ways to create meso-scale geometries, such simulations require reliable meshing algorithms. While the former is made possible via dedicated textile pre-processors or high-fidelity weaving simulations, the meshing remains quite problematic for complex textiles and geometries. Even though, with a lot of user input, it is possible to create very complex meshes using meshing pre-processors, this approach remains infeasible for cases when a large number of models need to be analysed.This paper presents a meshing approach based on the combination of local octree-refinement with surface smoothing. This allows nearly conformal meshes to be generated for geometries of any complexity which achieve accuracy comparable to that of conformal meshes. A range of unit cells was analysed using the new approach and it was shown that the error in local stresses is within 10% of the reference solution and the average error is below 7%. It was found that the computational cost of the analysis using the new meshing technique is not considerably higher than for an analysis which uses a conventional conformal mesh yet the new approach allows analysis of any geometry

Advanced geometry modelling of 3D woven reinforcements in polymer composites: processing and performance analysis

Numerical methods have become increasingly effective tools for analysis and design of composite materials. This study investigates how the inclusion of geometrical variations in modelling 3D woven fabrics affects the accuracy of numerical predictions. Based on micro-Computed Tomography data of 3D orthogonal woven composites, unit cell models were generated in TexGen at different levels of geometrical detail. Two types of analysis were implemented: (a) computational fluid dynamics (CFD) simulates resin flow during fabric impregnation in composites processing to predict permeability; (b) implicit static finite element analysis predicts in-plane tensile strength of the composites. By comparison with experimental data, the numerical predictions indicate that local geometrical variations, particularly in yarn cross-section, surface crimp and binder yarn path, have significant influence on both permeability and material strength. It is important to model the precise geometry in certain locations while the overall geometry can be simplified in order to maintain the practicality of model generation

Recent developments in the realistic geometric modelling of textile structures using TexGen

Realistic geometric representation of fabrics is essential for modelling of mechanical and physical properties of textiles and textile composites. It is also advantageous to be able to generate those models quickly and easily. Recent developments in TexGen which automate the creation of models for 3D orthogonal, angle interlock and layer-to-layer fabrics and sheared 2D fabrics are described. Micro-Computed Tomography data of 3D fabrics has been used to identify geometrical characteristics which have formed the basis for implementation of refinements to the idealised fabrics generated automatically in TexGen. In 3D orthogonal textiles local geometrical variations, particularly in yarn cross-section, surface crimp and binder yarn path are apparent at different levels of compaction. The “refine” option in TexGen‟s 3D wizard automatically adjusts these features to achieve compaction to a specified thickness, using yarn volume fraction as a constraint. For sheared textiles a generic 2D plain weave fabric was used to identify key geometric features. Yarn rotation has been identified as one of these and the geometric description of the sheared fabric considers yarn rotations in terms of two elliptical cylinders crossing each other at an oblique angle. The rotational angle is derived mathematically from the tangential contact between yarns. Variations in yarn height along the length of the yarn have also been identified and both of these features are incorporated into a refine function for sheared textiles. Compatible voxelised mesh and periodic boundary conditions for the sheared domain have also been implemented. The models have been used to generate manufacturing data: permeability data for the 3D fabric and coefficient of thermal expansion for the sheared 2D fabric

Modelling framework for optimum multiaxial 3D woven textile composites

The application of 3D weaves has advantages over conventional uni-directional or 2D woven lay-ups. There is potential to produce near net-shaped preforms and to increase damage resistance due to the presence of through thickness reinforcement. Conventional 3D weaves typically consist of orthogonal yarns interwoven with through thickness binder yarns. This paper describes a feasibility study to find optimum architectures for 3D woven fabrics where some of the normal manufacturing constraints are relaxed. This will provide the basis for development of novel manufacturing methods based on optimum textile architectures. A framework has been developed for the automatic generation and analysis of 3D textile geometries, utilising the open-source pre-processor TexGen. A genetic algorithm is used to select an optimum geometry by evaluating results from finite element simulations using the commercial solver Abaqus. This paper highlights the flexibility of TexGen software to create complex 3D models by means of its Python scripting application programming interface (API). A standard layer-to-layer geometry is used as a starting point to which off-axis yarn rotations, in-plane shift of entire layers and adjustments to binder yarns can be applied. Geometric variables are selected to represent the textile architecture enabling the automation of unit cell creation and finite element analysis. A Genetic Algorithm is used to determine the optimum through thickness binder path, the number and the width of the binders, and yarn angles using a weighted objective function of the material elastic properties. The case studies show that the algorithm is efficient to converge to the optimum fibre architecture

Recent developments in the realistic geometric modelling of textile structures using TexGen

Realistic geometric representation of fabrics is essential for modelling of mechanical and physical properties of textiles and textile composites. It is also advantageous to be able to generate those models quickly and easily. Recent developments in TexGen which automate the creation of models for 3D orthogonal, angle interlock and layer-to-layer fabrics and sheared 2D fabrics are described. Micro-Computed Tomography data of 3D fabrics has been used to identify geometrical characteristics which have formed the basis for implementation of refinements to the idealised fabrics generated automatically in TexGen. In 3D orthogonal textiles local geometrical variations, particularly in yarn cross-section, surface crimp and binder yarn path are apparent at different levels of compaction. The “refine” option in TexGen‟s 3D wizard automatically adjusts these features to achieve compaction to a specified thickness, using yarn volume fraction as a constraint. For sheared textiles a generic 2D plain weave fabric was used to identify key geometric features. Yarn rotation has been identified as one of these and the geometric description of the sheared fabric considers yarn rotations in terms of two elliptical cylinders crossing each other at an oblique angle. The rotational angle is derived mathematically from the tangential contact between yarns. Variations in yarn height along the length of the yarn have also been identified and both of these features are incorporated into a refine function for sheared textiles. Compatible voxelised mesh and periodic boundary conditions for the sheared domain have also been implemented. The models have been used to generate manufacturing data: permeability data for the 3D fabric and coefficient of thermal expansion for the sheared 2D fabric

Mesoscale geometric modelling of bifurcation in 3D woven T-beam preforms

Manipulation of the through-thickness yarn path enables 3D woven reinforcement to separate locally in the form of a bifurcation, creating net-shaped preforms for T- and I-beams. Preforming introduces fibre architecture deformation at the 3D woven bifurcation area. We report a geometric modelling approach to represent the realistic fibre architecture, as a preprocessing tool for finite element analyses. The study started with x-ray micro-computed tomography (µCT) of two 3D woven T-beams varying only by their yarn path at the T-junction area. Supported by the µCT image analysis, a set of mathematical formula were proposed to describe the identified features in the 3D woven T-beams. We then moved on to implement the automated modelling procedure in the open-source software TexGen. Using the weave pattern as input data, TexGen first simulates as-woven flat T-piece. Next, TexGen applies geometric transformation and refinements to simulate the preforming process of T-beams. The paper highlights an efficient approach to model the complex woven bifurcation structure at mesoscale

Mesoscale geometric modelling of bifurcation in 3D woven T-beam preforms

Manipulation of the through-thickness yarn path enables 3D woven reinforcement to separate locally in the form of a bifurcation, creating net-shaped preforms for T- and I-beams. Preforming introduces fibre architecture deformation at the 3D woven bifurcation area. We report a geometric modelling approach to represent the realistic fibre architecture, as a preprocessing tool for finite element analyses. The study started with x-ray micro-computed tomography (µCT) of two 3D woven T-beams varying only by their yarn path at the T-junction area. Supported by the µCT image analysis, a set of mathematical formula were proposed to describe the identified features in the 3D woven T-beams. We then moved on to implement the automated modelling procedure in the open-source software TexGen. Using the weave pattern as input data, TexGen first simulates as-woven flat T-piece. Next, TexGen applies geometric transformation and refinements to simulate the preforming process of T-beams. The paper highlights an efficient approach to model the complex woven bifurcation structure at mesoscale

Candida albicans Hypha Formation and Mannan Masking of β-Glucan Inhibit Macrophage Phagosome Maturation

Received 28 August 2014 Accepted 28 October 2014 Published 2 December 2014 This is an open-access article distributed under the terms of the Creative Commons Attribution 3.0 Unported license. ACKNOWLEDGMENTS We thank Janet Willment, Aberdeen Fungal Group, University of Aberdeen, for kindly providing the soluble Dectin-1-Fc reporter. All microscopy was performed with the assistance of the University of Aberdeen Core Microscopy & Histology Facility, and we thank the IFCC for their assistance with flow cytometry. We thank the Wellcome Trust for funding (080088, 086827, 075470, 099215, 097377, and 101873). E.R.B. and A.J.P.B. are funded by the European Research Council (ERC-2009-AdG-249793), and J.L. is funded by a Medical Research Council Clinical Training Fellowship.Peer reviewedPublisher PD