117 research outputs found

    Shear viscosity of a highly excited string and the black hole membrane paradigm

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    Black hole membrane paradigm states that a certain viscous membrane seems to be sitting on a stretched horizon of a black hole from the viewpoint of a distant observer. We show that the shear viscosity of the fictitious membrane can be reproduced by a highly excited string covering the stretched horizon except for a numerical coefficient.Comment: 22 pages, no figure, minor correction

    Solution of the Stochastic Langevin Equations for Clustering of Particles in Turbulent Flows in Terms of Wiener Path Integral

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    We propose to take advantage of using the Wiener path integrals as the formal solution for the joint probability densities of coupled Langevin equations describing particles suspended in a fluid under the effect of viscous and random forces. Our obtained formal solution, giving the expression for the Lyapunov exponent, i) will provide the description of all the features and the behaviour of such a system, e.g. the aggregation phenomenon recently studied in the literature using appropriate approximations, ii) can be used to determine the occurrence and the nature of the aggregation - non-aggregation phase transition which we have shown for the one-dimensional case and iii) allows the use of a variety of approximative methods appropriate for the physical conditions of the problem such as instanton solutions in the WKB approximation in the aggregation phase for the one-dimensional case as presented in this paper. The use of instanton approximation gives the same result for the Lyapunov exponent in the aggregation phase, previously obtained by other authors using a different approximative method. The case of non-aggregation is also considered in a certain approximation using the general path integral expression for the one-dimensional case.Comment: 18 pages; added section III C containing WKB method (instanton approximation) for the evaluation of the path integral in the aggregation, as well as non-aggregation, phase

    Photocatalysis of functionalised 3D printed cementitious materials

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    The main objective of this study was to evaluate the photocatalytic behaviour of 3D printed cementitious mortars that were functionalised with TiO2 nanoparticles. This study is one of the few available regarding functionalisation of 3D concrete printing (3DCP) with photocatalytic properties. Despite the fact 3DCP research is swiftly growing, it is still necessary further investigation to fully understand these materials’ physicochemical and mechanical properties, which will influence the functionalised properties of the composite. Due to the freeform nature of the 3DCP there are no moulds, therefore the functionalisation through coating can be performed in a much earlier stage than in conventional moulded concrete. The developed smart 3D printed concrete could promote the photodegradation of pollutants for self-cleaning and air purification. In particular, this study investigated the effect of two parameters on photocatalytic behaviour: light power intensity and the coating rate of nano-TiO2 particles. Surface coating was adopted as the functionalisation method, and the Rhodamine B dye degradation efficiency was used as an indicator to evaluate the photocatalytic behaviour. Additionally, the surface roughness and microstructure of the 3D printed cementitious mortar specimens were assessed to distinguish between the reference and TiO2 coated series. Scanning electron microscopy (SEM), X-ray Energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) crystallography were carried out as three techniques to evaluate the morphology, composition, and microstructure of the specimens, respectively. The results indicated successful activation of catalyst particles under illumination, where higher light power intensity increased the degradation efficiency. Furthermore, dye degradation efficiency increased with increasing coating rates of nano-TiO2 particles on the surface of the specimens. The roughness of the 3D printed specimens’ surface was sufficient for settling the nano-TiO2 particles. Finally, microscopy results confirmed the presence and suitable distribution of the nano-TiO2 particles on the surface of the coated specimens.Support SECIL, SIKA, ELKEM and UNIBETAO, which graciously provided the required materials for printing the cementitious specimensThis work was partly financed by Fundaç˜ao para a Ciˆencia e a Tecnologia (FCT)/MCTES through national funds (PIDDAC) under the R&D Unit Institute for Sustainability and Innovation in Structural Engineering (ISISE), under reference UIDB/04029/2020. The authors acknowledge the support of DST group construction company for funding the project Chair dst/IB-S: Smart Systems for Construction. The first two authors would like to acknowledge the PhD grants SFRH/BD/143636/2019 and SFRH/BD/137421/2018 provided by the Portuguese Foundation for Science and Technology (FCT). Additionally, the authors would like to acknowledge FCT for the financing this research work by the project NanoAir PTDC/FIS-MAC/6606/2020 and the Strategic Funding UIDB/04650/ 2020–2023

    The Impact of Low Advanced Glycation End Products Diet on Metabolic Risk Factors: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

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    Several randomized clinical trials have investigated the effect of dietary advanced glycation end products (AGEs) on metabolic syndrome risk factors in adults. However, the results of these studies were conflicting. Therefore, our aim was to assess the effect of dietary AGEs on metabolic syndrome risk factors. We searched the PubMed-MEDLINE, Scopus, Cochrane Databases, Google Scholar, Web of Science, and Embase databases for papers published up to October 2019 that investigated the effect of dietary AGEs on metabolic syndrome risk factors. From the eligible trials, 13 articles were selected for inclusion in this systematic review and meta-analysis. The meta-analysis was performed using a random-effects model. Heterogeneity was determined by I2 statistics and Cochrane Q test. Pooled results from the random-effects model showed a significant reduction for insulin resistance weighted mean difference (WMD): -1.204; 95% CI: -2.057, -0.358; P = 0.006, fasting insulin (WMD: -5.472 μU/mL; 95% CI: -9.718, -1.234 μU/mL; P = 0.011), total cholesterol (WMD: -5.486 mg/dL; 95% CI: -10.222, -0.747 mg/dL; P = 0.023), and LDL (WMD: -6.263 mg/dL; 95% CI: -11.659, -0.866 mg/dL; P = 0.023) in the low-AGEs groups compared with the high-AGEs groups. There were no changes in the other components of the metabolic syndrome. The results of this review suggest that a diet with a low AGEs content has beneficial effects on insulin resistance, fasting insulin, total cholesterol, and LDL. Moreover, following a diet low in AGEs may be a helpful strategy to decrease the burden of metabolic syndrome risk factors in adults and particularly in patients with diabetes. © 2020 The Author(s). Published by Oxford University Press on behalf of the American Society for Nutrition

    Analysis of Advanced Driver-Assistance Systems in Police Vehicles

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    69A3551747115/[TTI-05-02]Motor vehicle crashes are the leading cause of death for police officers. Advanced driver assistance systems (ADAS) have the potential to improve officer safety by removing some of the driver\u2019s vehicle control responsibilities. This project included two phases: (1) an ADAS needs and implementation analysis in police vehicles; and (2) an evaluation of police ADAS in a driving simulation study. The first phase included a systematic review of literature and an online survey with officers to understand their ADAS needs and current systems in police vehicles. The second phase evaluated ADAS in high-demand situations using a high-fidelity driving simulator. Results indicated that officer behaviors and opinions on ADAS features were influenced by the trust officers had in the available ADAS, as well as other key factors such as ADAS training and perceived usefulness. ADAS features, including forward collision warning, automatic emergency braking, and blind spot monitoring had a positive effect on police officers' driving performance and in reducing workload. The outcomes of this project provide guidelines regarding effective ADAS features/types to automotive companies supplying police vehicles and can improve officer safety in police operations

    Cyber-risk in Healthcare: Exploring Facilitators and Barriers to Secure Behaviour

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    There are increasing concerns relating to cybersecurity of healthcare data and medical devices. Cybersecurity in this sector is particularly important given the criticality of healthcare systems, the impacts of a breach or cyberattack (including in the worst instance, potential physical harm to patients) and the value of healthcare data to criminals. Technology design is important for cybersecurity, but it is also necessary to understand the insecure behaviours prevalent within healthcare. It is vital to identify the drivers behind these behaviours, i.e., why staff may engage in insecure behaviour including their goals and motivations and/or perceived barriers preventing secure behaviour. To achieve this, in-depth interviews with 50 staff were conducted at three healthcare sites, across three countries (Ireland, Italy and Greece). A range of seven insecure behaviours were reported: Poor computer and user account security; Unsafe e-mail use; Use of USBs and personal devices; Remote access and home working; Lack of encryption, backups and updates; Use of connected medical devices; and poor physical security. Thematic analysis revealed four key facilitators of insecure behaviour: Lack of awareness and experience, Shadow working processes, Behaviour prioritisation and Environmental appropriateness. The findings suggest three key barriers to security: i) Security perceived as a barrier to productivity and/or patient care; ii) Poor awareness of consequences of behaviour; and iii) a lack of policies and reinforcement of secure behaviour. Implications for future research are presented

    Electronic Medical Records: Provotype visualisation maximises clinical usability

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    The Electronic Medical Record (EMR) is the essential tool of the clinical consultation, effectively replacing the paper medical record. Since its gradual adoption in the early 2000s there has been a failure to achieve even moderate levels of EMR usability in clinical settings, resulting in a negative impact on clinical care, time efficiency and patient safety. This research explores how deeper collaboration with clinical users through participatory design, drawing on the disciplines of visual design, user experience (UX) design and visual analytics, might offer a more effective approach to this important problem. The lead researcher for this project is both a practising doctor and design researcher. Usability of two commercial EMR interfaces in the field of sexual health is explored through a mixed method survey, with responses used to inform the design of an interface provotype. This in turn is evaluated through repeat survey and ‘test-drive’ talk-aloud workshops. Results from the survey on two commercial EMR interfaces (n=49) revealed deep dissatisfaction particularly around issues of navigation, flow of consultation, frustration, safety, time-dependent and time-independent data, data complexity and data salience. Comparative provotype evaluation (n=63) showed that clinically-relevant visualisation offers marked gains in clinical usability and performance. This research argues for a re-imagining of the way we look at medical data during the clinical consultation so that the affordances and benefits of the digital format can be exploited more fully. It highlights the value of combining participatory design with visualisation to embed explicit, experiential and even tacit clinical knowledge into the EMR interface

    Mapping geographical inequalities in childhood diarrhoeal morbidity and mortality in low-income and middle-income countries, 2000–17 : analysis for the Global Burden of Disease Study 2017

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    Background Across low-income and middle-income countries (LMICs), one in ten deaths in children younger than 5 years is attributable to diarrhoea. The substantial between-country variation in both diarrhoea incidence and mortality is attributable to interventions that protect children, prevent infection, and treat disease. Identifying subnational regions with the highest burden and mapping associated risk factors can aid in reducing preventable childhood diarrhoea. Methods We used Bayesian model-based geostatistics and a geolocated dataset comprising 15 072 746 children younger than 5 years from 466 surveys in 94 LMICs, in combination with findings of the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2017, to estimate posterior distributions of diarrhoea prevalence, incidence, and mortality from 2000 to 2017. From these data, we estimated the burden of diarrhoea at varying subnational levels (termed units) by spatially aggregating draws, and we investigated the drivers of subnational patterns by creating aggregated risk factor estimates. Findings The greatest declines in diarrhoeal mortality were seen in south and southeast Asia and South America, where 54·0% (95% uncertainty interval [UI] 38·1–65·8), 17·4% (7·7–28·4), and 59·5% (34·2–86·9) of units, respectively, recorded decreases in deaths from diarrhoea greater than 10%. Although children in much of Africa remain at high risk of death due to diarrhoea, regions with the most deaths were outside Africa, with the highest mortality units located in Pakistan. Indonesia showed the greatest within-country geographical inequality; some regions had mortality rates nearly four times the average country rate. Reductions in mortality were correlated to improvements in water, sanitation, and hygiene (WASH) or reductions in child growth failure (CGF). Similarly, most high-risk areas had poor WASH, high CGF, or low oral rehydration therapy coverage. Interpretation By co-analysing geospatial trends in diarrhoeal burden and its key risk factors, we could assess candidate drivers of subnational death reduction. Further, by doing a counterfactual analysis of the remaining disease burden using key risk factors, we identified potential intervention strategies for vulnerable populations. In view of the demands for limited resources in LMICs, accurately quantifying the burden of diarrhoea and its drivers is important for precision public health

    Global burden of 369 diseases and injuries in 204 countries and territories, 1990-2019: a systematic analysis for the Global Burden of Disease Study 2019

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