Impact of edge-removal on the centrality betweenness of the best spreaders

The control of epidemic spreading is essential to avoid potential fatal consequences and also, to lessen unforeseen socio-economic impact. The need for effective control is exemplified during the severe acute respiratory syndrome (SARS) in 2003, which has inflicted near to a thousand deaths as well as bankruptcies of airlines and related businesses. In this article, we examine the efficacy of control strategies on the propagation of infectious diseases based on removing connections within real world airline network with the associated economic and social costs taken into account through defining appropriate quantitative measures. We uncover the surprising results that removing less busy connections can be far more effective in hindering the spread of the disease than removing the more popular connections. Since disconnecting the less popular routes tend to incur less socio-economic cost, our finding suggests the possibility of trading minimal reduction in connectivity of an important hub with efficiencies in epidemic control. In particular, we demonstrate the performance of various local epidemic control strategies, and show how our approach can predict their cost effectiveness through the spreading control characteristics.Comment: 11 pages, 4 figure

Fast algorithm for scattering from planar arrays of conducting patches

Cataloged from PDF version of article.A direct (noniterative) algorithm for the solution of the electromagnetic scattering from three-dimensional planar arrays of conducting patches is developed. For an N-unknown problem, the computational complexity of this new solution technique is shown to be O(N2 log2N), which is considerably lower than the O(N3) computational complexity of the conventional direct solution techniques. The advantages of the reduction in the computational complexity is pronounced in the solution of large electromagnetics problems, such as scattering from large and finite arrays of patches, synthesis and analysis of finite-sized frequency selective surfaces (FSS’s), and radiation and scattering from large phased-array antennas, to name a few

The scattering of a cylindrical invisibility cloak: reduced parameters and optimization

We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak by using some peculiar composites like photonic crystals (PCs) which mimic an effective refractive index landscape rather than offering effective constitutives, meanwhile canceling the scattering from the inner and outer boundaries.Comment: Accepted for J. Phys.

Efficiency of tunable band-gap structures for single-photon emission

The efficiency of recently proposed single-photon emitting sources based on tunable planar band-gap structures is examined. The analysis is based on the study of the total and ``radiative'' decay rates, the expectation value of emitted radiation energy and its collimating cone. It is shown that the scheme operating in the frequency range near the defect resonance of a defect band-gap structure is more efficient than the one operating near the band edge of a perfect band-gap structure.Comment: 9 pages, 7 figure

How do people with knee osteoarthritis perceive and manage flares? A qualitative study

Background Acute flares in people with osteoarthritis (OA) are poorly understood. There is uncertainty around the nature of flares, their impact, and how these are managed. Aim To explore understandings and experiences of flares in people with knee OA, and to describe self-management and help-seeking strategies. Design & setting Qualitative interview study of people with knee OA in England. Method Semi-structured interviews were undertaken with 15 people with knee OA. Thematic analysis was applied using constant comparison methods. Results The following four main themes were identified: experiencing pain; consequences of acute pain; predicting and avoiding acute pain; and response to acute pain. People with OA described minor episodes that were frequent, fleeting, occurred during everyday activity, had minimal impact, and were generally predictable. This contrasted with severe episodes that were infrequent, had greater impact, and were less likely to be predictable. The latter generally led to feelings of low confidence, vulnerability, and of being a burden. The term ‘flare’ was often used to describe the severe events but this was applied inconsistently and some would describe a flare as any increase in pain. Participants used numerous self-management strategies but tended to seek help when these had been exhausted, their symptoms led to emotional distress, disturbed sleep, or pain experience worse than usual. Previous experiences shaped whether people sought help and who they sought help from. Conclusion Severe episodes of pain are likely to be synonymous with flares. Developing a common language about flares will allow a shared understanding of these events, early identification, and appropriate management

Experiences of general practice care for self-harm: A qualitative study of young people's perspectives

Background Self-harm is a growing concern and rates of self-harm in young people (aged 12–25 years) presenting to general practice are rising. There is, however, little evidence about young people’s experiences of GP care and on accessing general practice. Aim To explore the help-seeking behaviours, experiences of GP care, and access to general practice of young people who self-harm. Design and setting In this qualitative study, semi-structured interviews were conducted with young people aged 16–25 years from England with previous self-harm behaviour. Method Interviews with 13 young people took place between April and November 2019. Young people were recruited from the community, third-sector organisations, and Twitter. Data were analysed using reflexive thematic analysis with principles of constant comparison. A patient and public involvement advisory group informed recruitment strategies and supported interpretation of findings. Results Young people described the avenues of help-seeking they employ and reflected on the mixed experiences of seeing GPs that can influence future help-seeking. Preconceptions and a lack of knowledge about accessing general practice were found to be barriers to help-seeking. GPs who attempt to understand the young person and establish relationship-based care can facilitate young people accessing general practice for self-harm. Conclusion It is important young people are aware of how to access general practice and that GPs listen, understand, and proactively follow-up young people who self-harm. Supporting young people with self-harm behaviour requires continuity of care

Exterior optical cloaking and illusions by using active sources: a boundary element perspective

Recently, it was demonstrated that active sources can be used to cloak any objects that lie outside the cloaking devices [Phys. Rev. Lett. \textbf{103}, 073901 (2009)]. Here, we propose that active sources can create illusion effects, so that an object outside the cloaking device can be made to look like another object. invisibility is a special case in which the concealed object is transformed to a volume of air. From a boundary element perspective, we show that active sources can create a nearly "silent" domain which can conceal any objects inside and at the same time make the whole system look like an illusion of our choice outside a virtual boundary. The boundary element method gives the fields and field gradients (which can be related to monopoles and dipoles) on continuous curves which define the boundary of the active devices. Both the cloaking and illusion effects are confirmed by numerical simulations