1.
Samokhin, Alexander, et al.
(författare)
Stationary iteration methods for solving 3D electromagnetic scattering problems
2013
Ingår i: Applied Mathematics and Computation. - : Elsevier BV. - 0096-3003 .- 1873-5649. ; 222, s. 107-122
Tidskriftsartikel (refereegranskat) abstract
Generalized Chebyshev iteration (GCI) applied for solving linear equations with nonselfadjoint operators is considered. Sufficient conditions providing the convergence of iterations imposed on the domain of localization of the spectrum on the complex plane are obtained. A minimax problem for the determination of optimal complex iteration parameters is formulated. An algorithm of finding an optimal iteration parameter in the case of arbitrary location of the operator spectrum on the complex plane is constructed for the generalized simple iteration method. The results are applied to numerical solution of volume singular integral equations (VSIEs) associated with the problems of the mathematical theory of wave diffraction by 3D dielectric bodies. In particular, the domain of the spectrum location is described explicitly for low-frequency scattering problems and in the general case. The obtained results are discussed and recommendations concerning their applications are given. (C) 2013 Elsevier Inc. All rights reserved.
2.
Vranjes, Ivana, et al.
(författare)
What Goes Around Comes Around : How Perpetrators of Workplace Bullying Become Targets Themselves
2023
Ingår i: Group & Organization Management. - : Sage Publications. - 1059-6011 .- 1552-3993. ; 48:4, s. 1135-1172
Tidskriftsartikel (refereegranskat) abstract
In this study, we investigated whether and how perpetrators of bullying become targets themselves. Building on the notion of bullying as an escalation process and the Conservation of Resources Theory, we hypothesized that following enactment of bullying, people would experience increased relationship conflicts with colleagues, diminishing their sense of control and making them more likely to become exposed to bullying themselves. We tested this idea using longitudinal sequential mediated Structural Equation Modelling in a sample of 1420 Belgian workers. Our results confirmed that enactment of bullying lead to more exposure to bullying 18 months later. Relationship conflicts partially mediated this effect, meaning that bullying enactment can lead to increased tensions with others at work, increasing one’s vulnerability to bullying exposure. Although perceived control also mediated the enactment-exposure relationship, relationship conflicts did not lead to perceived loss of control, suggesting a missing link in this relationship. Furthermore, the effect from perceived control to exposure to bullying was small and did not replicate in post-hoc analyses. Our findings suggest that people may experience a backlash from others in their work environment following engagement in bullying behavior at work and invite further exploration of the processes that may account for this relationship.
3.
Rohman, Ibrahim Kholilul, 1980, et al.
(författare)
Who Enjoys ICT Development? An Investigation into the Role of ICT Development in Asian Countries Using Dynamic Panel Data
2010
Ingår i: 5th Communication Policy Research South Conference (CPRsouth5), XI'an, China.
Konferensbidrag (refereegranskat) abstract
Asian countries are at different development stages in the building of an information and communication technology (ICT) industry. Although East Asian countries, especially Japan and Korea, have reached a high penetration rate of broadband and telephony, most of the South and South-East Asian countries are still at the early stage of the diffusion process. It is even more interesting that some Asian countries have recently achieved robust growth in the penetration rate of particular ICT devices, for instance, cellular ones, amid sluggish socio-economic performance. This phenomenon raises the question of how the contribution by ICT affects society and who enjoys the development of this sector? In order to address these questions, this study aims to relate the network externality with regard to socio-economic variables included in the calculation of the Human Development Index (HDI): educational attainment and health (life-expectancy rate). The ICT variables of the analysis include the penetration rate of the fixed-line, Internet subscriber, computer and TV. The study covers roughly 35 selected Asian countries that represent all the sub-regions in Asia based on the World Bank and International Telecommunication Union’s database, and the figures range in time from 1983 to 2005. The study first identifies the unit root test and then builds cointegration between the series. As there are many gaps in the data, the Maddala-Wu (1999) estimation is implemented while the Westerlund (2007) cointegration test is applied to non-stationary series. The results are quite surprising in that most ICT device development has no statistical evidence of cointegration with socio-economic variables. Primary education has very weak cointegration with the development of ICT devices however. Thus, there is a need for further innovation in this sector to provide more socio-economic devices to support a better level of welfare.
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6.
Verendel, Vilhelm, 1980, et al.
(författare)
Measuring Traffic in Cities Through a Large-Scale Online Platform
2019
Ingår i: Journal of Big Data Analytics in Transportation. - : Springer Science and Business Media LLC. - 2523-3564 .- 2523-3556. ; 1:2-3, s. 161-173
Tidskriftsartikel (refereegranskat) abstract
Online real-time traffic data services could effectively deliver traffic information to people all over the world and provide large benefits to the society and research about cities. Yet, city-wide road network traffic data are often hard to come by on a large scale over a longer period of time. We collect, describe, and analyze traffic data for 45 cities from HERE, a major online real-time traffic information provider. We sampled the online platform for city traffic data every 5 min during 1 year, in total more than 5 million samples covering more than 300 thousand road segments. Our aim is to describe some of the practical issues surrounding the data that we experienced in working with this type of data source, as well as to explore the data patterns and see how this data source provides information to study traffic in cities. We focus on data availability to characterize how traffic information is available for different cities; it measures the share of road segments with real-time traffic information at a given time for a given city. We describe the patterns of real-time data availability, and evaluate methods to handle filling in missing speed data for road segments when real-time information was not available. We conduct a validation case study based on Swedish traffic sensor data and point out challenges for future validation. Our findings include (i) a case study of validating the HERE data against ground truth available for roads and lanes in a Swedish city, showing that real-time traffic data tends to follow dips in travel speed but miss instantaneous higher speed measured in some sensors, typically at times when there are fewer vehicles on the road; (ii) using time series clustering, we identify four clusters of cities with different types of measurement patterns; and (iii) a k-nearest neighbor-based method consistently outperforms other methods to fill in missing real-time traffic speeds. We illustrate how to work with this kind of traffic data source that is increasingly available to researchers, travellers, and city planners. Future work is needed to broaden the scope of validation, and to apply these methods to use online data for improving our knowledge of traffic in cities.
7.
Al-Zoubi, Noura, et al.
(författare)
Influence of manganese on the bulk properties of Fe-Cr-Mn alloys : a first-principles study
2014
Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 89:12, s. 125702-
Tidskriftsartikel (refereegranskat) abstract
We investigate the effect of manganese on lattice stability and magnetic moments of paramagnetic Fe-Cr-Mn steel alloys along the Bain path connecting the body-centered cubic (bcc) and face-centered cubic (fcc) structures. The calculations are carried out using the ab initio exact muffin-tin orbital method, in combination with the coherent potential approximation, and the paramagnetic phase is modeled by the disordered local magnetic moment scheme. For all Fe-Cr-Mn alloys considered here, the local magnetic moments on Fe atoms have the minimum values for the fcc structure and the maximum values for the bcc structure, whereas the local magnetic moments on Mn have almost the same value along the constant-volume Bain path. Our results show that Mn addition to paramagnetic Fe-Cr solid solution stabilizes the bcc structure. However, when considering the paramagnetic fcc phase relative to the ferromagnetic bcc ground state, then Mn turns out to be a clear fcc stabilizer, in line with observations.
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9.
dos Santos Soares, Ricardo de Oliveira, et al.
(författare)
Membrane vesiculation induced by proteins of the dengue virus envelope studied by molecular dynamics simulations
2017
Ingår i: Journal of Physics. - : Institute of Physics Publishing (IOPP). - 0953-8984 .- 1361-648X. ; 29:50
Tidskriftsartikel (refereegranskat) abstract
Biological membranes are continuously remodeled in the cell by specific membrane-shaping machineries to form, for example, tubes and vesicles. We examine fundamental mechanisms involved in the vesiculation processes induced by a cluster of envelope (E) and membrane (M) proteins of the dengue virus (DENV) using molecular dynamics simulations and a coarse-grained model. We show that an arrangement of three E-M heterotetramers (EM3) works as a bending unit and an ordered cluster of five such units generates a closed vesicle, reminiscent of the virus budding process. In silico mutagenesis of two charged residues of the anchor helices of the envelope proteins of DENV shows that Arg-471 and Arg-60 are fundamental to produce bending stress on the membrane. The fine-tuning between the size of the EM3 unit and its specific bending action suggests this protein unit is an important factor in determining the viral particle size.
10.
Fedeli, Stefano, et al.
(författare)
Privacy Preserving Survival Prediction
2021
Ingår i: 2021 IEEE INTERNATIONAL CONFERENCE ON BIG DATA (BIG DATA). - : Institute of Electrical and Electronics Engineers (IEEE). ; , s. 4600-4608
Konferensbidrag (refereegranskat) abstract
Predictive modeling has the potential to improve risk stratification of cancer patients and thereby contribute to optimized treatment strategies and better outcomes for patients in clinical practice. To develop robust predictive models for decision-making in healthcare, sensitive patient-level data is often required when developing the training models. Consequently, data privacy is an important aspect to consider when building these predictive models and in subsequent communication of the results. In this study we have used Graph Neural Networks for survival prediction, and compared the accuracy to state-of-the-art prediction models after applying Differential Privacy and k-Anonymity, i.e. two privacy-preservation solutions. By using two different data sources we demonstrated that Graph Neural Networks and Survival Forests are the two most well-performing survival prediction methods when used in combination with privacy preservation solutions. Furthermore, when the predictive model was built using clinical expertise in the specific area of interest, the prediction accuracy of the proposed knowledge based graph model drops by at most 10% when used with privacy preservation solutions. Our proposed knowledge based graph is therefore more suitable to be used in combination with privacy preservation solutions as compared to other graph models.
