Intrinsically Dynamic Network Communities

Community finding algorithms for networks have recently been extended to dynamic data. Most of these recent methods aim at exhibiting community partitions from successive graph snapshots and thereafter connecting or smoothing these partitions using clever time-dependent features and sampling techniques. These approaches are nonetheless achieving longitudinal rather than dynamic community detection. We assume that communities are fundamentally defined by the repetition of interactions among a set of nodes over time. According to this definition, analyzing the data by considering successive snapshots induces a significant loss of information: we suggest that it blurs essentially dynamic phenomena - such as communities based on repeated inter-temporal interactions, nodes switching from a community to another across time, or the possibility that a community survives while its members are being integrally replaced over a longer time period. We propose a formalism which aims at tackling this issue in the context of time-directed datasets (such as citation networks), and present several illustrations on both empirical and synthetic dynamic networks. We eventually introduce intrinsically dynamic metrics to qualify temporal community structure and emphasize their possible role as an estimator of the quality of the community detection - taking into account the fact that various empirical contexts may call for distinct `community' definitions and detection criteria.Comment: 27 pages, 11 figure

The Zodiac Policy Subsystem: A Policy-Based Management System for a High-Security MANET

Zodiac (Zero Outage Dynamic Intrinsically Assurable Communities) is an implementation of a high-security MANET, resistant to multiple types of attacks, including Byzantine faults. The Zodiac architecture poses a set of unique system security, performance, and usability requirements to its policy-based management system (PBMS). In this paper, we identify theses requirements, and present the design and implementation of the Zodiac Policy Subsystem (ZPS), which allows administrators to securely specify, distribute and evaluate network control and system security policies to customize ZODIAC behaviors. ZPS uses the Keynote language for specifying all authorization policies. We also present a simple extension of the Keynote language to support obligation policies

Disordered proteins and network disorder in network descriptions of protein structure, dynamics and function. Hypotheses and a comprehensive review

During the last decade, network approaches became a powerful tool to describe protein structure and dynamics. Here we review the links between disordered proteins and the associated networks, and describe the consequences of local, mesoscopic and global network disorder on changes in protein structure and dynamics. We introduce a new classification of protein networks into ‘cumulus-type’, i.e., those similar to puffy (white) clouds, and ‘stratus-type’, i.e., those similar to flat, dense (dark) low-lying clouds, and relate these network types to protein disorder dynamics and to differences in energy transmission processes. In the first class, there is limited overlap between the modules, which implies higher rigidity of the individual units; there the conformational changes can be described by an ‘energy transfer’ mechanism. In the second class, the topology presents a compact structure with significant overlap between the modules; there the conformational changes can be described by ‘multi-trajectories’; that is, multiple highly populated pathways. We further propose that disordered protein regions evolved to help other protein segments reach ‘rarely visited’ but functionally-related states. We also show the role of disorder in ‘spatial games’ of amino acids; highlight the effects of intrinsically disordered proteins (IDPs) on cellular networks and list some possible studies linking protein disorder and protein structure networks

Economic resilience : including a case study of the global transition network

This paper explores the dynamic properties of organisms and ecosystems that make them so resilient and capable of adapting to changing circumstances, allowing them to maintain an overall condition of coherence, wholeness and health while living in balance within the resources of the planet. Key principles of resilient ecological systems are explored including: self-regulation; positive and negative feedback; diversity; scale and context; cooperation; emergence and novelty; and ecological tipping points. In contrast, market based economic systems can produce unstable growth with unintended destruction of cultural and species diversity and homogenisation of global life-styles. The paper re-examines fundamental economic principles using insights from biological evolution and ecosystem dynamics to establish a foundation for more resilient economies. This involves experimenting with different models in different communities to find patterns of sustainable production and exchange appropriate to local regions. Fundamental steps in this direction include the emergence of self-organising local communities based on creative experimentation, re-localisation of core sectors of the economy (food, energy, health and education), evolution of local currencies and banking practices that support local enterprise and investment in green technologies, stimulation of decentralised renewable energy networks and economic reform aligned with ecological principles. The Transition Network provides a case study of an international community based movement that has been experimenting with putting some of these principles into practice at the local level. The aim of the Transition Network is to support community led responses to peak oil and climate change, building resilience and well-being. The concept of ecological resilience and its application to local economy is hard wired into the values and emerging structure of the network of transition communities across the globe. The movement started in the UK in 2005 and there are now over 1000 Transition initiatives spanning 34 countries across the world. Many attribute the success and phenomenal growth of the Transition Network to its emerging holographic structure that mimics cell growth within living organisms. Growing a more resilient food system in the face of the twin challenges of natural resource scarcity and climate change is central to the Transition movement. A set of principles for a post carbon resilient food economy in the UK are offered. These include an 80% cut in carbon emission in the food sector by 2050, agricultural diversification, prioritization of farming methods that establish and enhance carbon sinks, phasing out of dependence on fossil fuels in food growing, processing and distribution, promoting access to nutritious and affordable food, as well as promoting greater access to land for growing food in urban and peri-urban areas. Practical examples of Transition related projects in the food sector are presented across the following themes: access to land, low carbon production methods, food distribution systems, health and community gardens and orchards, and collaborative ownership models

Detecting the community structure and activity patterns of temporal networks: a non-negative tensor factorization approach

The increasing availability of temporal network data is calling for more research on extracting and characterizing mesoscopic structures in temporal networks and on relating such structure to specific functions or properties of the system. An outstanding challenge is the extension of the results achieved for static networks to time-varying networks, where the topological structure of the system and the temporal activity patterns of its components are intertwined. Here we investigate the use of a latent factor decomposition technique, non-negative tensor factorization, to extract the community-activity structure of temporal networks. The method is intrinsically temporal and allows to simultaneously identify communities and to track their activity over time. We represent the time-varying adjacency matrix of a temporal network as a three-way tensor and approximate this tensor as a sum of terms that can be interpreted as communities of nodes with an associated activity time series. We summarize known computational techniques for tensor decomposition and discuss some quality metrics that can be used to tune the complexity of the factorized representation. We subsequently apply tensor factorization to a temporal network for which a ground truth is available for both the community structure and the temporal activity patterns. The data we use describe the social interactions of students in a school, the associations between students and school classes, and the spatio-temporal trajectories of students over time. We show that non-negative tensor factorization is capable of recovering the class structure with high accuracy. In particular, the extracted tensor components can be validated either as known school classes, or in terms of correlated activity patterns, i.e., of spatial and temporal coincidences that are determined by the known school activity schedule

Synchronization reveals topological scales in complex networks

We study the relationship between topological scales and dynamic time scales in complex networks. The analysis is based on the full dynamics towards synchronization of a system of coupled oscillators. In the synchronization process, modular structures corresponding to well defined communities of nodes emerge in different time scales, ordered in a hierarchical way. The analysis also provides a useful connection between synchronization dynamics, complex networks topology and spectral graph analysis.Comment: 4 pages, 3 figure

Knowledge and Information Economy, Welfare and governance: the economic nature of Intellectual Property Rights

В даній статті аналізуються підходи до оцінки економічної природи інтелектуальної власності та її використання з урахуванням економічної категорії благополуччя. Зокрема в статті доведено, що транзакційні витрати використання нематеріальних активів, зокрема прав інтелектуальної вартості значно перевищують витрати пов’язні на їх державне регулювання. Ефективність державного регулювання (ліцензування, обмеження, контроль, власність держави) значно перевищує витрати на переговори між контрагентами по впровадженню інтелектуальних прав власності. В дослідженнях «неокласиків» по просуванню інтелектуальних прав власності враховуються лише витрати на виробництво, проте транзакційні витрати ринкових механізмів не беруться до уваги. В роботі доведено, що підходи неокласичної економічної школи не можуть використовуватися для оцінки таких комплексних товарів як нематеріальні активи. Теоретичні результати дослідження полягають в тому, що приватні переговори та ринкова ефективність використання прав інтелектуальної власності не можуть бути досягнуті без інституціонального втручання, тобто без державного регулювання, необхідного для підтримки умов соціальної справедливості. Проблема забезпечення ефективності функціонування інтелектуальних прав власності полягає не лише в урахуванні виробничих витрат, а навпаки, необхідно брати до уваги транзакційні та колективні витрати. Враховуючи всю комплексність нематеріального капіталу в роботі показано обмеження теорії Коуза та обґрунтовано її відмінності з теорією Вільямсона для нематеріальних активів. Зокрема, що стосується теорії Коуза, доведено необхідність використання інституціонального посередника та регулятора для досягнення соціальної та ринкової ефективності. Ринкові механізми довели свою низьку ефективність при регулюванні та функціонуванні такої категорії благ як нематеріальні активи. В висновках можна стверджувати, що для інтелектуальних прав власності приватні переговори та ринкові механізми просування зазначених категорій товарів не забезпечують бажаний соціальний ефект, основною причиною ринкових провалів можна назвати специфіку та комплексність нематеріальних активів, неповноту та асиметричність інформації. Проведений аналіз може бути використаний в різних сферах пов’язаних з нематеріальними активами: просування товарів екологічної спрямованості, культурні товари, освітні послуги, виробництво інформації, економіка Інтернету. При цитуванні документа, використовуйте посилання http://essuir.sumdu.edu.ua/handle/123456789/9144This paper will study the different conceptions about economic nature of (Intelectual) Property Rights, and the implications in regard to Welfare. This analysis may be applied in various fields concerned with intangible components: ecology, cultural goods, knowledge and information production, internet economics, for example. In regard to the complexity of these types of intangible capital, I will show the limits of the private negotiation inspired in Coase´s approach, and underline the opposition between this approach and the Williamson´s one. При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/914