Engineering, United Kingdom
Engineering, United Kingdom

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Casswell S.,Massey University | Meier P.,University of Sheffeld | MacKintosh A.M.,University of Stirling | Brown A.,University of Stirling | And 8 more authors.
Alcoholism: Clinical and Experimental Research | Year: 2012

Background:: This paper describes a new multicountry collaborative project to assess the impact of alcohol control policy. Longitudinal surveys of drinkers in a number of participating countries and analysis of the policy context allow for the assessment of change over time within countries and comparison between countries. The design of the study is modeled on the International Tobacco Control study and aims to assess the impact of alcohol policies in different cultural contexts on policy-related behaviors and alcohol consumption. A survey instrument and protocol for policy analysis have been developed by the initial participating countries: England, Scotland, Thailand, South Korea, and New Zealand. The first round of data collection is scheduled for 2011-2012. Measurements:: The survey instrument (International Alcohol Control [IAC] survey) measures key policy relevant behaviors: place and time of purchase, amounts purchased and price paid; ease of access to alcohol purchase; alcohol marketing measures; social supply; perceptions of alcohol affordability and availability and salience of price; perceptions of enforcement; people's experiences with specific alcohol restrictions; support for policy and consumption (typical quantity, frequency using beverage and location-specific measures). The Policy Analysis Protocol (PoLAP) assesses relevant aspects of the policy environment including regulation and implementation. Results:: It has proved feasible to design instruments to collect detailed data on behaviors relevant to alcohol policy change and to assess the policy environment in different cultural settings. Conclusions:: In a policy arena in which the interest groups and stakeholders have different perceptions of appropriate policy responses to alcohol-related harm, a robust methodology to assess the impact of policy will contribute to the debate. © 2012 by the Research Society on Alcoholism.

Mazumdar S.,University of Sheffeld | Lanfranchi V.,University of Sheffeld | Cano A.E.,Open University Milton Keynes | Ciravegna F.,University of Sheffeld
CEUR Workshop Proceedings | Year: 2013

Advancements in mobile technology and the proliferation of social media platforms have made it possible for individuals to stay constantly connected with friends and family. This has provided new opportunities to the emergency response domain, where the information shared by individuals in crisis can provide invaluable insight into the situation on the ground. Information shared on social media is highly dynamic, heterogeneous, large scale, geographically distributed and multilingual. Moreover, the context of such information is mostly relevant for a very short period of time and the information can be very subjective, embedded in personal feelings. This is a significant challenge for the emergency response domain, where critical decisions need to be made quickly on the basis of the users' situation awareness. We propose to address this issue using visual analytics techniques to facilitate browsing and understanding of topicality and feelings in social media. Our approach is twofoldrstly, we enrich social media posts by adding semantics to facilitate browsing and sentiment in order to gauge the emotions behind individual posts. Secondly, we combine two paradigms of data browsing - topical and temporal into a real-time dynamic visualisation of social media messages.

Mazumdar S.,University of Sheffeld | Kauppinen T.,University of Bremen | Kauppinen T.,Aalto University
CEUR Workshop Proceedings | Year: 2014

Visual exploration of data enables users and analysts observe interesting patterns that can trigger new research for further investigation. With the increasing availability of Linked Data, facilitating support for making sense of the data via visual exploration tools for hypothesis generation is critical. Time and space play important roles in this because of their ability to illustrate dynamicity, from a spatial context. Yet, Linked Data visualization approaches typically have not made efficient use of time and space together, apart from typical rather static multi-visualization approaches and mashups. In this paper we demonstrate ELBAR explorer that visualizes a vast amount of scientific observational data about the Brazilian Amazon Rainforest. Our core contribution is a novel mechanism for animating between the different observed values, thus illustrating the observed changes themselves.

Salman N.,University of Sheffeld | Alsindi N.,Eisala Briish Telecom Innovaion Cener EBTIC | Mihaylova L.,University of Sheffeld | Kemp A.H.,University of Leeds
2014 Workshop on Sensor Data Fusion: Trends, Solutions, Applications, SDF 2014 | Year: 2014

In this paper, we present a complete framework for accurate indoor positioning and tracking using the 802.11a WiFi network. Channel frequency response is first estimated via the least squares (LS) method using an orthogonal frequency division multiplexing (OFDM) pilot symbol. For accurate time of arrival (ToA) distance estimates in multipath environments, super resolution technique i.e. Multiple Signal Classification (MUSIC) is used which capitalizes on the autocorrelation matrix of the estimated channel frequency response. The estimated distances from the base stations (BSs) are then used in the observation model for particle filter (PF) tracking for which a constant velocity motion model is used, depicting indoor mobile movement. The tracking performance of the combined MUSIC-PF is compared with PF performance when a conventional cross correlator (CC) is used for delay estimates. It is shown via simulation that the MUSIC-PF performance is superior to the CC-PF performance. © 2014 IEEE.

Su D.,University of Tokyo | Nakano K.,University of Tokyo | Zheng R.,University of Tokyo | Cartmell M.P.,University of Sheffeld
International Journal of Structural Stability and Dynamics | Year: 2014

The recent potential benefit of nonlinearity has been applying in order to improve the effectiveness of energy harvesting devices. For instance, at relatively high excitation levels, both low and high-energy responses can coexist for the same parameter combinations in a hardening type Duffing oscillator, and this provides a wider bandwidth and a higher energy harvesting effectiveness under periodic excitations. However, frequency or amplitude sweeps of the excitation must be used in order to reach a desirable high-energy orbit, and this gives a limitation on practical implementation. This paper presents a stifness tunable nonlinear vibrational energy harvester which contains a moving magnetic end mass attached to a cantilever beam, whose nonlinearity emerges from the interaction forces with two neighboring permanent magnets facing with opposing poles. The motivating hypothesis has been that the jump from the low-energy orbit to the high-energy orbit can be triggered by tuning the stifness of the system without changing the frequency or the amplitude of the excitation. Theoretical investigations show a methodology for tuning stifness, and experimental tests have validated that theproposed method can be used to trigger a jump to the desirable state, and hereby this can broaden the bandwidth of the energy harvester. © 2014 World Scientific Publishing Company.

Toric N.,University of Split | Sun R.R.,MMI Engineering Inc. | Burgess I.W.,University of Sheffeld
Journal of Structural Fire Engineering | Year: 2016

Purpose-This paper aims to propose a methodology to remove inherent implicit creep from the Eurocode 3 material model for steel and to present a creep-free analysis on simply supported steel members. Design/methodology/approach-Most of the available material models of steel are based on transient coupon tests, which inherently include creep strain associated with particular heating rates and load ratios. Findings-The creep-free analysis aims to reveal the in?uence of implicit creep by investigating the behaviour of simply supported steel beams and columns exposed to various heating regimes. The paper further evaluates the implicit consideration of creep in the Eurocode 3 steel material model. Originality/value-A modifed Eurocode 3 carbon steel material model for creep-free analysis is proposed for general structural fre engineering analysis. © Emerald Group Publishing Limited.

Hensman J.,University of Sheffeld | Matthews A.G.,University of Cambridge | Ghahramani Z.,University of Cambridge
Journal of Machine Learning Research | Year: 2015

Gaussian process classification is a popular method with a number of appealing properties. We show how to scale the model within a variational inducing point framework, outperforming the state of the art on benchmark datasets. Importantly, the variational formulation can be exploited to allow classification in problems with millions of data points, as we demonstrate in experiments. Copyright 2015 by the authors.

Lightman E.G.,University of Sheffeld | Harrison M.R.M.,University of Sheffeld | Cunliffe V.T.,University of Sheffeld
International Journal of Developmental Biology | Year: 2011

The rate and pattern of neurogenesis in the developing vertebrate nervous system are controlled by a complex interplay of intercellular signalling pathways and transcriptional control mechanisms. In the zebrafsh hindbrain, Fgf20a promotes transcription of the gene encoding the ETS-domain transcription factor Erm in the non-neurogenic centres of rhombomeres. Here, we demonstrate that the epigenetic regulator, Histone Deacetylase 1 (Hdac1) and the Notch signalling pathway have opposing functions in regulating expression of both erm and fgf20a in the zebrafsh hindbrain. Our results show that Hdac1 is required for expression of erm and fgf20a in rhombome-res, and that the Hdac1-dependent expression of these two genes is attenuated in rhombomere boundary regions by Notch signalling activity, thereby restricting erm and fgf20a transcripts to narrow stripes of cells at rhombomere centres. © 2011 UBC Press.

Goodacre S.,University of Sheffeld | Thokala P.,University of Sheffeld | Carroll C.,University of Sheffeld | Stevens J.W.,University of Sheffeld | And 6 more authors.
Health Technology Assessment | Year: 2013

Background: Current practice for suspected acute coronary syndrome (ACS) involves troponin testing 10-12 hours after symptom onset to diagnose myocardial infarction (MI). Patients with a negative troponin can be investigated further with computed tomographic coronary angiography (CTCA) or exercise electrocardiography (ECG). objectives: We aimed to estimate the diagnostic accuracy of early biomarkers for MI, the prognostic accuracy of biomarkers for major adverse cardiac adverse events (MACEs) in troponin-negative patients, the diagnostic accuracy of CTCA and exercise ECG for coronary artery disease (CAD) and the prognostic accuracy of CTCA and exercise ECG for MACEs in patients with suspected ACS. We then aimed to estimate the cost-effectiveness of using alternative biomarker strategies to diagnose MI, and using biomarkers, CTCA and exercise ECG to risk-stratify troponin-negative patients. Data sources: We searched MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations; Cumulative Index of Nursing and Allied Health Literature (CINAHL), EMBASE, Web of Science, Cochrane Central Database of Controlled Trials (CENTRAL), Cochrane Database of Systematic Reviews (CDSR), NHS Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment database from 1985 (CTCA review) or 1995 (biomarkers review) to November 2010, reviewed citation lists and contacted experts to identify relevant studies. Review methods: Diagnostic studies were assessed using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS) tool and prognostic studies using a framework adapted for the project. Meta-analysis was conducted using Bayesian Markov chain Monte Carlo simulation. We developed a decision-analysis model to evaluate the cost-effectiveness of alternative biomarker strategies to diagnose MI, and the cost- effectiveness of biomarkers, CTCA or exercise ECG to risk-stratify patients with a negative troponin. Strategies were applied to a theoretical cohort of patients with suspected ACS. Cost-effectiveness was estimated as the incremental cost per quality-adjusted life-year (QALY) of each strategy compared with the next most effective, taking a health-service perspective and a lifetime horizon. Results: Sensitivity and specifcity (95% predictive interval) were 77% (29-96%) and 93% (46-100%) for troponin I, 80% (33-97%) and 91% (53-99%) for troponin T (99th percentile threshold), 81% (50-95%) and 80% (26-98%) for quantitative heart-type fatty acid-binding protein (H-FABP), 68% (11-97%) and 92% (20-100%) for qualitative H-FABP, 77% (19-98%) and 39% (2-95%) for ischaemia-Modified albumin and 62% (35-83%) and 83% (35-98%) for myoglobin. CTCA had 94% (61-99%) sensitivity and 87% (16-100%) specifcity for CAD. Positive CTCA and positive-exercise ECG had relative risks of 5.8 (0.6-24.5) and 8.0 (2.3-22.7) for MACEs. In most scenarios in the economic analysis presentation, high-sensitivity troponin measurement was the most effective strategy with an incremental cost-effectiveness ratio (ICER) of less than the £20,000-30,000/QALY threshold (ICER £7487-17,191/QALY). CTCA appeared to be the most cost-effective strategy for patients with a negative troponin, with an ICER of £11,041/QALY. However, when a lower MACE rate was assumed, CTCA had a high ICER (£262,061/QALY) and the no-testing strategy was optimal. limitations: There was substantial variation between the primary studies and heterogeneity in their results. Findings of the economic model were dependent on assumptions regarding the value of detecting and treating positive cases. conclusions: Although presentation troponin has suboptimal sensitivity, measurement of a 10-hour troponin level is unlikely to be cost-effective in most scenarios compared with a high-sensitivity presentation troponin. CTCA may be a cost-effective strategy for troponin-negative patients, but further research is required to estimate the effect of CTCA on event rates and health-care costs. Funding: The National Institute for Health Research Health Technology Assessment programme. © Queen's Printer and Controller of HMSO 2013.

Bernal S.A.,University of Valle | Bernal S.A.,University of Sheffeld | Rodriguez E.D.,University of Valle | De Gutierrez R.M.,University of Valle | Provis J.L.,University of Sheffeld
Materiales de Construccion | Year: 2015

This study assessed the mechanical properties, and structural changes induced by high temperature exposure, of alkali-silicate activated slag cements produced with sodium silicates derived from silica fume (SF) and rice husk ash (RHA). Similar reaction products were identified, independent of the type of silicate used, but with subtle differences in the composition of the C-S-H gels, leading to different strength losses after elevated temperature exposure. Cements produced with the alternative activators developed higher compressive strengths than those produced with commercial silicate. All samples retained strengths of more than 50 MPa after exposure to 600 °C, however, after exposure to 800 °C only the specimens produced with the RHA-based activator retained measurable strength. This study elucidated that silicate-activated slag binders, either activated with commercial silicate solutions or with sodium silicates based on SF or RHA, are stable up to 600 °C. © 2015 CSIC.

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