Hide and seek on complex networks

Signaling pathways and networks determine the ability to communicate in systems ranging from living cells to human society. We investigate how the network structure constrains communication in social-, man-made and biological networks. We find that human networks of governance and collaboration are predictable on teat-a-teat level, reflecting well defined pathways, but globally inefficient. In contrast, the Internet tends to have better overall communication abilities, more alternative pathways, and is therefore more robust. Between these extremes the molecular network of Saccharomyces cerevisea is more similar to the simpler social systems, whereas the pattern of interactions in the more complex Drosophilia melanogaster, resembles the robust Internet.Comment: 5 pages, 5 figure

Efficient Bitrate Ladder Construction for Content-Optimized Adaptive Video Streaming

One of the challenges faced by many video providers is the heterogeneity of network specifications, user requirements, and content compression performance. The universal solution of a fixed bitrate ladder is inadequate in ensuring a high quality of user experience without re-buffering or introducing annoying compression artifacts. However, a content-tailored solution, based on extensively encoding across all resolutions and over a wide quality range is highly expensive in terms of computational, financial, and energy costs. Inspired by this, we propose an approach that exploits machine learning to predict a content-optimized bitrate ladder. The method extracts spatio-temporal features from the uncompressed content, trains machine-learning models to predict the Pareto front parameters, and, based on that, builds the ladder within a defined bitrate range. The method has the benefit of significantly reducing the number of encodes required per sequence. The presented results, based on 100 HEVC-encoded sequences, demonstrate a reduction in the number of encodes required when compared to an exhaustive search and an interpolation-based method, by 89.06% and 61.46%, respectively, at the cost of an average Bj{\o}ntegaard Delta Rate difference of 1.78% compared to the exhaustive approach. Finally, a hybrid method is introduced that selects either the proposed or the interpolation-based method depending on the sequence features. This results in an overall 83.83% reduction of required encodings at the cost of an average Bj{\o}ntegaard Delta Rate difference of 1.26%

Strong excitons in novel two-dimensional crystals: Silicane and germanane

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Development of a psychological intervention to promote meaningful activity in people living with mild dementia: an intervention mapping approach

Background and Objectives: Despite the importance of meaningful activity in mild dementia, only limited data are available on the development of interventions supporting people with mild dementia to engage in meaningful activity. In this article, we describe the development of an intervention that responds to this need. Research Design and Methods: Intervention mapping (IM), an evidence-based approach, was used to develop STAYING ACTIVE (STAYing well and active—schedulINg meaninGful and enjoyAble aCTIvities to promote Vitality and wEll-being in mild dementia). The first step, a needs assessment, comprised a literature review, focus groups, and individual interviews with service users. Performance objectives of the intervention were formulated in Step 2, followed by the development of theory-based methods in Step 3. In Step 4, the new intervention was developed based on data collected in previous steps, existing interventions, and pilot testing. Qualitative data were analyzed using framework analysis. Results: The needs assessment indicated that people with dementia and their carers view “staying active” as an important part of “enjoying life.” Adapting to loss through compensation and receiving support were key facilitators of engaging in meaningful activity. Ecological, psychosocial, and activity-oriented theories guided the development of theory-based intervention strategies, which were based on awareness, skills, and addressing barriers of meaningful activity. Discussion and Implications: STAYING ACTIVE is grounded on theory, and service user experiences and aims at promoting meaningful activity in mild dementia. The IM framework may be useful in the development of future psychosocial interventions for people with dementia, facilitating transparency when efficacy is evaluated

Optimal network topologies for local search with congestion

The problem of searchability in decentralized complex networks is of great importance in computer science, economy and sociology. We present a formalism that is able to cope simultaneously with the problem of search and the congestion effects that arise when parallel searches are performed, and obtain expressions for the average search cost--written in terms of the search algorithm and the topological properties of the network--both in presence and abscence of congestion. This formalism is used to obtain optimal network structures for a system using a local search algorithm. It is found that only two classes of networks can be optimal: star-like configurations, when the number of parallel searches is small, and homogeneous-isotropic configurations, when the number of parallel searches is large.Comment: 4 pages. Final version accepted in PR

On classical finite and affine W-algebras

This paper is meant to be a short review and summary of recent results on the structure of finite and affine classical W-algebras, and the application of the latter to the theory of generalized Drinfeld-Sokolov hierarchies.Comment: 12 page