Variation in the thickness of a fluid interface due to internal wave propagation:a lattice Boltzmann simulation

The change in the thickness of an interface between two immiscible fluids due to the propagation of an internal capillary-gravity wave along the interface is considered using a Bhatnagar, Gross and Krook (BGK) lattice Boltzmann model of a binary of fluid. The vertical thickness of the interface is recorded from the simulations since this is the most easily measured quantities in any simulation or experiment. The vertical thickness is then related to the actual thickness (perpendicular to the interface) which is seen to vary with the phase of the wave. The positions of the maxima and minimum thicknesses are seen to be approximately constant relative to the phase of the propagating wave and the range of variation of the thickness decreases at approximately the same rate as the wave amplitude is damped. A simplified model for the interface is considered which predicts a similar variation due to the interface being stretched as the internal wave propagates

Exploratory analysis using machine learning to predict for chest wall pain in patients with stage I non-small-cell lung cancer treated with stereotactic body radiation therapy.

Background and purposeChest wall toxicity is observed after stereotactic body radiation therapy (SBRT) for peripherally located lung tumors. We utilize machine learning algorithms to identify toxicity predictors to develop dose-volume constraints.Materials and methodsTwenty-five patient, tumor, and dosimetric features were recorded for 197 consecutive patients with Stage I NSCLC treated with SBRT, 11 of whom (5.6%) developed CTCAEv4 grade ≥2 chest wall pain. Decision tree modeling was used to determine chest wall syndrome (CWS) thresholds for individual features. Significant features were determined using independent multivariate methods. These methods incorporate out-of-bag estimation using Random forests (RF) and bootstrapping (100 iterations) using decision trees.ResultsUnivariate analysis identified rib dose to 1 cc < 4000 cGy (P = 0.01), chest wall dose to 30 cc < 1900 cGy (P = 0.035), rib Dmax < 5100 cGy (P = 0.05) and lung dose to 1000 cc < 70 cGy (P = 0.039) to be statistically significant thresholds for avoiding CWS. Subsequent multivariate analysis confirmed the importance of rib dose to 1 cc, chest wall dose to 30 cc, and rib Dmax. Using learning-curve experiments, the dataset proved to be self-consistent and provides a realistic model for CWS analysis.ConclusionsUsing machine learning algorithms in this first of its kind study, we identify robust features and cutoffs predictive for the rare clinical event of CWS. Additional data in planned subsequent multicenter studies will help increase the accuracy of multivariate analysis

Time-Splitting Coupling of WaveDyn with OpenFOAM by Fidelity Limit Identified from a WEC in Extreme Waves

Survivability assessment is the complexity compromising Wave energy development. The present study develops a hybrid model aiming to reduce computational power while maintaining accuracy for survivability assessment of a Point-Absorber (PA) Wave Energy Converter (WEC) in extreme Wave Structure Interaction (WSI). This method couples the fast inviscid linear potential flow time-domain model WaveDyn (1.2, DNV-GL, Bristol, UK) with the fully nonlinear viscous Navier–Stokes Computational Fluid Dynamics (CFD) code OpenFOAM (4.2, OpenFOAM.org, London, UK). The coupling technique enables the simulation to change between codes, depending on an indicator relating to wave steepness identified as a function of the confidence in the linear model solution. During the CFD part of the simulation, the OpenFOAM solution is returned to WaveDyn via an additional load term, thus including viscous effects. Developments ensure a satisfactory initialisation of CFD simulation to be achieved from a ‘hot-start’ time, where the wave-field is developed and the device is in motion. The coupled model successfully overcomes identified inaccuracies in the WaveDyn code due to the inviscid assumption and the high computational cost of the OpenFOAM code. Experimental data of a PA response under extreme deterministic events (NewWave) are used to assess WaveDyn’s validity limit as a function of wave steepness, in order to validate CFD code and develop the coupling. The hybrid code demonstrates the applicability of WaveDyn validity limit and shows promising results for long irregular sea-state applications

Design and development of a low-cost, electricity-generating cooking Score-Stove™

SCORE (www.score.uk.com) a US$4M, 5 year international collaboration research project aims to improve the life quality of the 1.5 billion people worldwide who cook on an open fire and do not have access to electricity. SCORE market evaluations1 indicate that at the upper-cost target of$120 with 20 Watts of electricity 60 million people would afford the stove. At the lower-cost target of $40 and 100 Watts it would be affordable to over 1 billion people. In November 2010, a wood burning Score-Stove™ prototype successfully developed 23 watts of electricity based on a planar Thermo-Acoustic Engine (TAE) [2],[3],[4],[5],[6] design, indicating that the new Score-Stove™ is now ready to be engaged with manufacturers to gear up for volume production, and therefore to meet the social and cooking requirements of the rural poor people. The development to a large-volume, easy to manufacture, low-cost TAE cooking stove using elements of the formal design methodologies of BS 7000 and TRIZ are discussed. By breaking down the system requirements into cost targets for each module, performing rig testing, and design refinements it is believed that the upper-cost target is achievable with the right level of investment

Wave energy converter arrays: Motion response of inter-connected array

Compact wave energy converter (WEC) arrays are a promising option in terms of opti-mizing energy output per unit area of marine space, realizing synergies in O&M tasks and auxiliary installations (substations, export cables, etc.), and achieving economies of scale. Four different levels of connectivity between five OWC spar buoys in a compact array—corresponding to as many mooring configurations—were tested in the Ocean Basin at the University of Plymouth. We find considerable implications of the inter-connectivity on the frequency of heave motion response, with interconnected cases yielding a higher natural frequency and an increase in magnitude compared to the baseline (non-connected) arrangement. This indicates the importance of a holistic inter-connected system design approach required in the early design stages with respect to the wave climate at the deployment site. For instance, for a site off Leixões (Portugal), the frequency upshift obtained through inter-connectivity may be beneficial

FeS-Induced Radical Formation and Its Effect on Plasmid DNA

Plasmid DNA was incubated at 25°C with aqueous solutions of dissolved Fe(II), S(-II), and nanoparticulate FeS with a mackinawite structure, FeSm. At ≥0.1 mM total dissolved Fe(II) and S(-II), an increase in the proportion of the relaxed plasmid DNA occurs, through scission of the DNA backbone. In solutions where FeSm was precipitated, nanoparticulate FeSm binds to the DNA molecules. In solutions with concentrations below the FeSm solubility product, nicking of supercoiled pDNA occurs. Plasmid DNA appears to be a sensitive proxy for radical reactions. The reactant is proposed to be a sulfur-based radical produced from the iron-catalyzed decomposition of bisulfide, in a manner analogous to the Fenton reaction. This is further supported by experiments that suggest that sulfide free radicals are produced during the photolysis of aqueous solutions of polysulfides. Supercoiling of DNA affects nearly all DNA–protein transactions so the observation of relaxation of supercoiled forms through reaction with FeS solutions has direct implications to biochemistry. The results of this experimentation suggest that genotoxicity in FeS-rich systems is a further contributory factor to the limited survival of organisms in sulfidic environments. Mutations resulting from the interactions of organisms and mobile elements, such as plasmids, in sediments will also be affected in sulfide-rich environments

Improving trial recruitment through improved communication about patient and public involvement : an embedded cluster randomised recruitment trial

Background: Evidence is emerging that patient and public involvement in research (PPIR) may improve recruitment into randomised controlled trials, but the best methods to achieve improvement are unclear. Although many trials use PPIR to improve design and conduct, many do not communicate their use of PPIR clearly to potential participants. Directly communicating PPIR might encourage participation through increased patient confidence and trust in a trial. We aimed to develop and evaluate the impact on recruitment an intervention communicating PPIR in a trial to potential participants. Methods: This study was embedded in EQUIP, a cluster randomised controlled trial which allocated mental health teams in England to either a training intervention group to improve service user and carer involvement in care planning, or to a control group (no training). We conducted a cluster randomised trial of a recruitment intervention communicating PPIR, embedded within the EQUIP trial. The principles underlying the intervention were informed by a systematic review and a workshop that included mental health service users and trialists. Working with EQUIP PPIR partners (service users and carers) we developed the intervention using a leaflet to advertise the nature and function of the PPIR. Professional graphic design optimised readability and impact. Patients identified as potentially eligible for EQUIP were randomised to receive the leaflet or not, alongside the standard trial information. The primary outcome was the proportion of participants enrolled in EQUIP. The secondary outcome was the proportion expressing interest in taking part. Results: 34 clusters (mental health teams) were recruited, and 8182 potential participants were randomised. Preliminary analyses show that for the primary outcome, 4% of patients receiving the PPIR leaflet were enrolled vs. 5.3% in the control group. For the secondary outcome 7.3% of potential participants receiving the PPIR leaflet responded positively to the invitation to participate, vs. 7.9% in the control group. Future analyses will be by intention-to-treat and use logistic regression to estimate between-group odds ratios (ORs) and corresponding 95% confidence intervals. A planned secondary analysis will explore whether the impact of the intervention is moderated by age and gender. Conclusion: In preliminary analysis of this large trial, communicating PPIR demonstrated no benefits for improving the numbers of potential participants expressing interest in the trial, and reduced trial enrolment. Our findings contrast with the literature suggesting PPIR benefits recruitment. We will discuss the potential reasons for this finding, along with implications for future recruitment practice and research

Mathematically gifted and talented learners: Theory and practice

This is an Author's Accepted Manuscript of an article published in International Journal of Mathematical Education in Science and Technology, 40(2), 213-228, 2009, copyright Taylor & Francis, available online at: http://www.tandfonline.com/10.1080/00207390802566907.There is growing recognition of the special needs of mathematically gifted learners. This article reviews policy developments and current research and theory on giftedness in mathematics. It includes a discussion of the nature of mathematical ability as well as the factors that make up giftedness in mathematics. The article is set in the context of current developments in Mathematics Education and Gifted Education in the UK and their implications for Science and Technology. It argues that early identification and appropriate provision for younger mathematically promising pupils capitalizes on an intellectual resource which could provide future mathematicans as well as specialists in Science or Technology. Drawing on a Vygotskian framework, it is suggested that the mathematically gifted require appropriate cognitive challenges as well as attitudinally and motivationally enhancing experiences. In the second half of this article we report on an initiative in which we worked with teachers to identify mathematically gifted pupils and to provide effective enrichment support for them, in a number of London Local Authorities. A number of significant issues are raised relating to the identification of mathematical talent, enrichment provision for students and teachers’ professional development