Visual query tools for uncertain data in space and time

Includes bibliographical references.The aim of our project was to develop query and visualisation tools for this archive of African art. Our query system had to be designed to cope with different degrees of uncertainty in data, both in time and space. One of our initial ideas was to use a geographic map to drive the interface to the system. Items were plotted as a point on the map at some random location which fell within the given location of uncertainty for the item. However, user feedback indicated that this approach was problematic, as users assumed that the point on the map was the actual location of the artwork. A better approach was found in driving the interface around a time-line metaphor

Search Trajectory Networks of Population-based Algorithms in Continuous Spaces

We introduce search trajectory networks (STNs) as a tool to analyse and visualise the behaviour of population-based algorithms in continuous spaces. Inspired by local optima networks (LONs) that model the global structure of search spaces, STNs model the search tra-jectories of algorithms. Unlike LONs, the nodes of the network are not restricted to local optima but instead represent a given state of the search process. Edges represent search progression between consecutive states. This extends the power and applicability of network-based models to understand heuristic search algorithms. We extract and analyse STNs for two well-known population-based algorithms: particle swarm optimi-sation and differential evolution when applied to benchmark continuous optimisation problems. We also offer a comparative visual analysis of the search dynamics in terms of merged search trajectory networks

Local Optima Networks for Continuous Fitness Landscapes

Local Optima Networks (LONs) have been proposed as a coarsegrained model of discrete (combinatorial) fitness landscapes, where nodes are local optima and edges are search transitions based on an exploration search operator. This paper presents one of the first complex network analysis of continuous fitness landscapes. We use benchmark functions with well-known global structure, and an existing implementation of a Basin-Hopping algorithm to extract the networks. We also explore the impact of varying the Basin-Hopping perturbation step-size. Our results suggest that the landscape's connectivity pattern (global structure) strongly varies with the perturbation step-size, with extreme values of this parameter being detrimental to search and fragmenting the global structure. Our LON visualisations strikingly illustrate the landscape's global (funnel) structure, indicating that LONs serve as a tool for visualising high-dimensional functions

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Proceedings of the 13th annual conference of INEBRIA

CITATION: Watson, R., et al. 2016. Proceedings of the 13th annual conference of INEBRIA. Addiction Science & Clinical Practice, 11:13, doi:10.1186/s13722-016-0062-9.The original publication is available at https://ascpjournal.biomedcentral.comENGLISH SUMMARY : Meeting abstracts.https://ascpjournal.biomedcentral.com/articles/10.1186/s13722-016-0062-9Publisher's versio

Adaptive landscape-aware constraint handling with application to binary knapsack problems

International audienceReal-world optimization problems frequently have constraints that define feasible and infeasible combinations of decision variables. Evolutionary algorithms do not inherently work with constraints, so they must be modified to include a suitable constraint handling technique (CHT) before they can be used to solve such problems. A range of different approaches to handling constraints have been used effectively with evolutionary algorithms, such as penaltybased, repair, feasibility rules, and bi-objective approaches. In this study we investigate different CHTs with an evolutionary algorithm on the 0/1 knapsack problem. We present results to show that performance complementarity exists between different CHTs on the knapsack problem. Landscape analysis is then used to characterize the search space of a large number of knapsack instances, and decision tree induction is used to derive rules for selecting the most appropriate CHT and switching it adaptively based on landscape features. We finally implement a landscape-aware CHT approach and show that it out-performs the constituent CHT approaches

Essential Java for scientists and engineers /

This text serves as an introduction to the programming language Java for scientists and engineers, as well as experienced programmers wishing to learn Java as an additional language. The authors have specifically taken a hands-on approach to get the reader writing and running programs immediately. In addition, the book focuses on how Java, and object-oriented programming, can be used to solve science and engineering problems. Many examples are included throughout, from a number of different scientific and engineering areas, as well as from business and everyday life, which demonstrate the prac.Includes index.Getting going -- Java programming basics -- Solving a problem in Java -- More on loops -- Debugging -- Arrays and matrices -- Inheritance -- Graphical user interfaces (GUIs) -- Input/output -- Exceptions -- Simulation -- Modelling with matrices -- Introduction to numerical methods.Print version record.This text serves as an introduction to the programming language Java for scientists and engineers, as well as experienced programmers wishing to learn Java as an additional language. The authors have specifically taken a hands-on approach to get the reader writing and running programs immediately. In addition, the book focuses on how Java, and object-oriented programming, can be used to solve science and engineering problems. Many examples are included throughout, from a number of different scientific and engineering areas, as well as from business and everyday life, which demonstrate the prac.Elsevie

Search trajectory networks: A tool for analysing and visualising the behaviour of metaheuristics

A large number of metaheuristics inspired by natural and social phenomena have been proposed in the last few decades, each trying to be more powerful and innovative than others. However, there is a lack of accessible tools to analyse, contrast and visualise the behaviour of metaheuristics when solving optimisation problems. When the metaphors are stripped away, are these algorithms different in their behaviour? To help to answer this question, we propose a data-driven, graph-based model, search trajectory networks (STNs) in order to analyse, visualise and directly contrast the behaviour of different types of metaheuristics. One strength of our approach is that it does not require any additional sampling or algorithmic methods. Instead, the models are constructed from data gathered while the metaheuristics are solving the optimisation problems. We present our methodology, and consider in detail two case studies covering both continuous and combinatorial optimisation. In terms of metaheuristics, our case studies cover the main current paradigms: evolutionary, swarm, and stochastic local search approaches

Semi-automated usability analysis through eye tracking

Usability of software is a crucial aspect of successful applications and could give one application a competitive edge over another. Eye tracking is a popular approach to usability evaluation, but is time consuming and requires expert analysis. This paper proposes a semi-automated process for identifying usability problems in applications with a task-based focus, such as business applications, without the need for expert analysis. The approach is demonstrated on the eye tracking data from a mobile procurement application involving 33 participants. With the recent inclusion of built-in eye tracking hardware in mobile devices, the proposed approach introduces the possibility of conducting remote, large-scale usability studies for improving user experience in mobile applications.http://sacj.cs.uct.ac.zaam2019Computer Scienc