WorldWideScience

Sample records for local ecological network

  1. Ecological Citizenship and Sustainable Consumption: Examining Local Organic Food Networks

    Science.gov (United States)

    Seyfang, Gill

    2006-01-01

    Sustainable consumption is gaining in currency as a new environmental policy objective. This paper presents new research findings from a mixed-method empirical study of a local organic food network to interrogate the theories of both sustainable consumption and ecological citizenship. It describes a mainstream policy model of sustainable…

  2. Ecological Citizenship and Sustainable Consumption: Examining Local Organic Food Networks

    Science.gov (United States)

    Seyfang, Gill

    2006-01-01

    Sustainable consumption is gaining in currency as a new environmental policy objective. This paper presents new research findings from a mixed-method empirical study of a local organic food network to interrogate the theories of both sustainable consumption and ecological citizenship. It describes a mainstream policy model of sustainable…

  3. Do Local Food Networks Foster Socio-Ecological Transitions towards Food Sovereignty? Learning from Real Place Experiences

    Directory of Open Access Journals (Sweden)

    Juliana Lutz

    2013-11-01

    Full Text Available Drawing on transition theory, we conceptualize local food networks as innovations that initially function and develop in local niches within a given food regime. As niche-innovations local food networks induce socio-ecological changes on the local level and they have the potential to foster wider transformations of the dominant food regime. Many local food networks adopt the concept of food sovereignty as a kind of “leitmotif”. At the core of this concept lies the question of how to create an agro-food system that, (i allows for democratic participation and civic engagement in food production, and (ii sets up new relationships that avoid social inequity and the exploitation of both humans and nature. In this paper we shed light on how the Austrian local food network “SpeiseLokal” addresses the challenge of operationalizing the concept of food sovereignty. The case study captures the strategies which local food networks embark on and depicts the difficulties they encounter. The paper aims to identify critical points of intersection that either strengthen or constrain local food networks from becoming established, operating, and up-scaling in the ways they wish; that is, in accordance with the principles and aims of food sovereignty, while avoiding a later assimilation into the dominant food regime.

  4. Molecular ecological network analyses

    Directory of Open Access Journals (Sweden)

    Deng Ye

    2012-05-01

    Full Text Available Abstract Background Understanding the interaction among different species within a community and their responses to environmental changes is a central goal in ecology. However, defining the network structure in a microbial community is very challenging due to their extremely high diversity and as-yet uncultivated status. Although recent advance of metagenomic technologies, such as high throughout sequencing and functional gene arrays, provide revolutionary tools for analyzing microbial community structure, it is still difficult to examine network interactions in a microbial community based on high-throughput metagenomics data. Results Here, we describe a novel mathematical and bioinformatics framework to construct ecological association networks named molecular ecological networks (MENs through Random Matrix Theory (RMT-based methods. Compared to other network construction methods, this approach is remarkable in that the network is automatically defined and robust to noise, thus providing excellent solutions to several common issues associated with high-throughput metagenomics data. We applied it to determine the network structure of microbial communities subjected to long-term experimental warming based on pyrosequencing data of 16 S rRNA genes. We showed that the constructed MENs under both warming and unwarming conditions exhibited topological features of scale free, small world and modularity, which were consistent with previously described molecular ecological networks. Eigengene analysis indicated that the eigengenes represented the module profiles relatively well. In consistency with many other studies, several major environmental traits including temperature and soil pH were found to be important in determining network interactions in the microbial communities examined. To facilitate its application by the scientific community, all these methods and statistical tools have been integrated into a comprehensive Molecular Ecological

  5. Evolving digital ecological networks.

    Science.gov (United States)

    Fortuna, Miguel A; Zaman, Luis; Wagner, Aaron P; Ofria, Charles

    2013-01-01

    "It is hard to realize that the living world as we know it is just one among many possibilities" [1]. Evolving digital ecological networks are webs of interacting, self-replicating, and evolving computer programs (i.e., digital organisms) that experience the same major ecological interactions as biological organisms (e.g., competition, predation, parasitism, and mutualism). Despite being computational, these programs evolve quickly in an open-ended way, and starting from only one or two ancestral organisms, the formation of ecological networks can be observed in real-time by tracking interactions between the constantly evolving organism phenotypes. These phenotypes may be defined by combinations of logical computations (hereafter tasks) that digital organisms perform and by expressed behaviors that have evolved. The types and outcomes of interactions between phenotypes are determined by task overlap for logic-defined phenotypes and by responses to encounters in the case of behavioral phenotypes. Biologists use these evolving networks to study active and fundamental topics within evolutionary ecology (e.g., the extent to which the architecture of multispecies networks shape coevolutionary outcomes, and the processes involved).

  6. Evolving digital ecological networks.

    Directory of Open Access Journals (Sweden)

    Miguel A Fortuna

    Full Text Available "It is hard to realize that the living world as we know it is just one among many possibilities" [1]. Evolving digital ecological networks are webs of interacting, self-replicating, and evolving computer programs (i.e., digital organisms that experience the same major ecological interactions as biological organisms (e.g., competition, predation, parasitism, and mutualism. Despite being computational, these programs evolve quickly in an open-ended way, and starting from only one or two ancestral organisms, the formation of ecological networks can be observed in real-time by tracking interactions between the constantly evolving organism phenotypes. These phenotypes may be defined by combinations of logical computations (hereafter tasks that digital organisms perform and by expressed behaviors that have evolved. The types and outcomes of interactions between phenotypes are determined by task overlap for logic-defined phenotypes and by responses to encounters in the case of behavioral phenotypes. Biologists use these evolving networks to study active and fundamental topics within evolutionary ecology (e.g., the extent to which the architecture of multispecies networks shape coevolutionary outcomes, and the processes involved.

  7. The dimensionality of ecological networks

    DEFF Research Database (Denmark)

    Eklöf, Anna; Jacob, Ute; Kopp, Jason;

    2013-01-01

    How many dimensions (trait-axes) are required to predict whether two species interact? This unanswered question originated with the idea of ecological niches, and yet bears relevance today for understanding what determines network structure. Here, we analyse a set of 200 ecological networks, incl...

  8. Ecological Networks in Urban Landscapes

    NARCIS (Netherlands)

    Cook, E.A.

    2000-01-01

    This research focuses on the topic of ecological networks in urban landscapes. Analysis and planning of ecological networks is a relatively new phenomenon and is a response to fragmentation and deterioration of quality of natural systems. In agricultural areas and with existing nature preserves this

  9. Local Social Networks

    DEFF Research Database (Denmark)

    Sapuppo, Antonio; Sørensen, Lene Tolstrup

    2011-01-01

    Online social networks have become essential for many users in their daily communication. Through a combination of the online social networks with opportunistic networks, a new concept arises: Local Social Networks. The target of local social networks is to promote social networking benefits...... in physical environment in order to leverage personal affinities in the users' surroundings. The purpose of this paper is to present and discuss the concept of local social networks as a new social communication system. Particularly, the preliminary architecture and the prototype of local social networks...

  10. The National Ecological Observatory Network

    Science.gov (United States)

    Michener, W. K.

    2006-05-01

    The National Ecological Observatory Network (NEON) is a research platform designed to advance understanding of how ecosystems and organisms respond to variations in climate and changes in land use. NEON is the first long-term ecological observatory conceived as a continental-scale network; equipped with standardized sensors, cyberinfrastructure, and data-collection protocols across the network; and designed to simultaneously address a common set of research questions and support investigator-driven ecological research in all regions of the United States. The Observatory focuses on variations in climate and land use because they are primary drivers of the Nation's environmental challenges, as identified by the National Research Council--i.e., biodiversity, biogeochemical cycles, climate change, hydroecology, infectious disease, invasive species, and land use. At the broadest scale, NEON links the complexity of climate variation to the behavior of ecological systems, a core aspect of ecological complexity. At the same time, because of the complexity of the interactions among humans and ecosystems, the network design includes NEON sites in wild, managed and urban systems within climate domains. Observatory data will also be part of a national education program designed to advance ecological science literacy through new programs and activities that develop and promote scientific ways of thinking.

  11. Resilience Through Ecological Network

    Directory of Open Access Journals (Sweden)

    Grazia Brunetta

    2014-05-01

    Full Text Available The paper explores the strategic role that urban biodiversity and ecosystem services management, natural infrastructure and adaptive governance approaches can play in making our economies and societies more resilient and in linking human societies and the natural environment. Resilience – a concept that entered the debate on urban governance – means the ability of urban systems, considered as linear-systems, to react to external disturbances by returning to some socio-ecological equilibrium steady-state by overcoming a crisis period (Gunderson & al. 2010, Newman & al. 2009. In this view, green infrastructures can assume a strategic role in restoring and enhancing the ecological and environmental livability in urban areas. Starting from the International and European context, the paper discusses innovative programs and interdisciplinary projects and practices (some cases in Turin Metropolitan Area to demonstrate how green infrastructures can increase the adaptive capacity of urban systems in term of resilience. They can contribute to increase the ability of European cities to adapt to climate change and to reduce their ecological footprints, to enhance security and life quality.

  12. European ecological networks and greenways

    NARCIS (Netherlands)

    Jongman, R.H.G.; Külvik, M.; Kristiansen, I.

    2004-01-01

    In the context of European integration, networks are becoming increasingly important in both social and ecological sense. Since the beginning of the 1990s, societal and scientific exchanges are being restructured as the conceptual approaches towards new nature conservation strategies have been renew

  13. European ecological networks and greenways

    DEFF Research Database (Denmark)

    Kristiansen, Ib; Jongman, Rob H.G.; Kulvik, Mart

    2004-01-01

    In the context of European integration, networks are becoming increasingly important in both social and ecological sense. Since the beginning of the 1990s, societal and scientific exchanges are being restructured as the conceptual approaches towards new nature conservation strategies have been re...

  14. Local Area Networks.

    Science.gov (United States)

    Marks, Kenneth E.; Nielsen, Steven

    1991-01-01

    Discusses cabling that is needed in local area networks (LANs). Types of cables that may be selected are described, including twisted pair, coaxial cables (or ethernet), and fiber optics; network topologies, the manner in which the cables are laid out, are considered; and cable installation issues are discussed. (LRW)

  15. The Mountain Invasion Research Network (MIREN): Linking Local and Global Scales for Addressing an Ecological Consequence of Global Change

    Science.gov (United States)

    Christoph Kueffer; Curtis Daehler; Hansjörg Dietz; Keith McDougall; Catherine Parks; Aníbal Pauchard; Lisa Rew

    2014-01-01

    Many modern environmental problems span vastly different spatial scales, from the management of local ecosystems to understanding globally interconnected processes, and addressing them through international policy. MIREN tackles one such “glocal” (global/local) environmental problem – plant invasions in mountains – through a transdisciplinary, multi-scale learning...

  16. Local area networks

    CERN Document Server

    Zafiropoulo, P

    1982-01-01

    Pitro Zafiropulo is a- staff member at the IBM Research Laboratories at Zurich. He joined IBM in 1968 and has worked on protocol validation, synthesis, integrated networks, network reliability, PABX's and speech recognition. Local Area Networks are intended to provide improved communication capabilities such as high data throughput rates, low error rates and ease of connection among terminal stations and comuters. These new types of networks operate within a limited geographical range like an establishment, campus or building and are owned by a single organization. The presentation introduces these networks and the main techniques are described. It then proceeds to evaluate the main switching techniques as they apply to LAN ring and bus configurations. The preferred technique of token-ring distributed switching is identified. The contents of Mr. Zafiropoulo's talk was somewhat similar to the paper of Mr. Kummerle, which is therefore included in these Proceedings.

  17. Interaction type influences ecological network structure more than local abiotic conditions: evidence from endophytic and endolichenic fungi at a continental scale.

    Science.gov (United States)

    Chagnon, Pierre-Luc; U'Ren, Jana M; Miadlikowska, Jolanta; Lutzoni, François; Arnold, A Elizabeth

    2016-01-01

    Understanding the factors that shape community assembly remains one of the most enduring and important questions in modern ecology. Network theory can reveal rules of community assembly within and across study systems and suggest novel hypotheses regarding the formation and stability of communities. However, such studies generally face the challenge of disentangling the relative influence of factors such as interaction type and environmental conditions on shaping communities and associated networks. Endophytic and endolichenic symbioses, characterized by microbial species that occur within healthy plants and lichen thalli, represent some of the most ubiquitous interactions in nature. Fungi that engage in these symbioses are hyperdiverse, often horizontally transmitted, and functionally beneficial in many cases, and they represent the diversification of multiple phylogenetic groups. We evaluated six measures of ecological network structure for >4100 isolates of endophytic and endolichenic fungi collected systematically from five sites across North America. Our comparison of these co-occurring interactions in biomes ranging from tundra to subtropical forest showed that the type of interactions (i.e., endophytic vs. endolichenic) had a much more pronounced influence on network structure than did environmental conditions. In particular, endophytic networks were less nested, less connected, and more modular than endolichenic networks in all sites. The consistency of the network structure within each interaction type, independent of site, is encouraging for current efforts devoted to gathering metadata on ecological network structure at a global scale. We discuss several mechanisms potentially responsible for such patterns and draw attention to knowledge gaps in our understanding of networks for diverse interaction types.

  18. Towards a network ecology of software ecosystems

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius; Manikas, Konstantinos

    2013-01-01

    of the ``network ecology'' approach to the analysis of natural ecosystems. In doing so, we mine the Maven central Java repository and analyze two OSGi ecosystems: Apache Felix and Eclipse Equinox. In particular, we define the concept of an ecosystem ``neighborhood'', apply network ecology metrics...

  19. The context and concept of ecological networks

    NARCIS (Netherlands)

    Jongman, R.H.G.

    2004-01-01

    This chapter introduces the reader to the development of concepts of ecological networks in general and the European approach to ecological networks in particular. It shows trends in decline of landscapes and the diversity of approaches to biodiversity conservation and nature conservation planning

  20. Regional power and local ecologies

    DEFF Research Database (Denmark)

    Lawrence, D.; Philip, G.; Wilkinson, K.

    2017-01-01

    Archaeological data tend to be gathered at the local level: human agency also operates at this scale. By combining data from multiple surveys conducted within a larger area, it is possible to use local datasets to obtain a perspective on regional trends in settlement, population, and human activi...... and climate are then examined side by side in order to assess long-term human interactions. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved....

  1. Local Area Networks: Part II.

    Science.gov (United States)

    Dessy, Raymond E., Ed.

    1982-01-01

    Discusses five approaches used by industry/colleges to provide local area network (LAN) capabilities in the analytical laboratory: (1) mixed baseband bus network coupled to a star net; (2) broadband bus network; (3) ring network; (4) star network coupled to broadband net; and (5) simple multiprocessor center. Part I (September issue) focused on…

  2. Local Area Networks (The Printout).

    Science.gov (United States)

    Aron, Helen; Balajthy, Ernest

    1989-01-01

    Describes the Local Area Network (LAN), a project in which students used LAN-based word processing and electronic mail software as the center of a writing process approach. Discusses the advantages and disadvantages of networking. (MM)

  3. Ecological networks in the Alpine Arc

    Directory of Open Access Journals (Sweden)

    Thomas Scheurer

    2009-07-01

    Full Text Available In response to decreasing biodiversity and new phenomena such as climate change, the number of initiatives aimed at creating ecological networks is increasing. Research and activities based on the theme of ecological connectivity are generating a completely new perception of methods of protecting the natural environment: there is a shift from a conservationist approach to natural systems to one that is more functional. The place and role of protected areas within their regions are being redefined. Such areas are now situated in a wider territorial context and new cooperative arrangements are encouraged with local actors. The alpine approach adopted in establishing a transalpine ecological network, illustrated by several examples, underlines the importance of both an international framework for such activities and the need to extend them to include not only the classic actors in the protection of the natural environment, but also other sectors that until now have seldom been involved.Face au constat d’une perte accrue de biodiversité et de phénomènes nouveaux, tels le changement climatique, les initiatives de mise en place de réseaux écologiques se multiplient. Les réflexions et les actions conduites autour de la thématique de la connectivité écologique font naître une perception complètement nouvelle des pratiques de la protection de la nature : un changement d’une conception patrimoniale conservatrice vers une approche plus fonctionnelle des systèmes naturels. La place et le rôle des espaces protégés au sein de leur région sont redéfinis, les situant  dans un contexte territorial plus large et engendrant de nouvelles collaborations entre acteurs locaux. L’approche alpine pour la réalisation d’un réseau écologique transalpin, illustrée par différents exemples, souligne l’importance d’un cadre international pour ces démarches et d’une ouverture sur l’ensemble du territoire impliquant en plus des acteurs

  4. Wireless sensor networks and ecological monitoring

    CERN Document Server

    Jiang, Joe-Air

    2013-01-01

    This book presents the state of the art technologies and solutions to tackle the critical challenges faced by the building and development of the WSN and ecological monitoring system but also potential impact on society at social, medical and technological level. This book is dedicated to Sensing systems for Sensors, Wireless Sensor Networks and Ecological Monitoring. The book aims at Master and PhD degree students, researchers, practitioners, especially WSN engineers involved with ecological monitoring. The book will provide an opportunity of a dedicated and a deep approach in order to improve their knowledge in this specific field.  

  5. Local Checkability in Dynamic Networks

    DEFF Research Database (Denmark)

    Förster, Klaus-Tycho; Richter, Oliver; Seidel, Jochen

    2017-01-01

    In this work we study local checkability of network properties considering inconsistency throughout the verification process. We use disappearing and appearing edges to model inconsistency and prover-verifier-pairs (PVPs) for verification. We say that a network property N is locally checkable und...

  6. Towards a network ecology of software ecosystems

    DEFF Research Database (Denmark)

    Hansen, Klaus Marius; Manikas, Konstantinos

    2013-01-01

    sharing and collaborating over one or more technological platforms and business model(s) that serve the actors. However, little research has investigated the properties of actual software ecosystems. In this paper, we present an exploratory study of software ecosystems using the formalizations and metrics...... of the "network ecology'' approach to the analysis of natural ecosystems. In doing so, we mine the Maven central Java repository and analyze two OSGi ecosystems: Apache Felix and Eclipse Equinox. In particular, we define the concept of an ecosystem ``neighborhood'', apply network ecology metrics...

  7. Localized attack on clustering networks

    CERN Document Server

    Dong, Gaogao; Du, Ruijin; Shao, Shuai; Stanley, H Eugene; Shlomo, Havlin

    2016-01-01

    Clustering network is one of which complex network attracting plenty of scholars to discuss and study the structures and cascading process. We primarily analyzed the effect of clustering coefficient to other various of the single clustering network under localized attack. These network models including double clustering network and star-like NON with clustering and random regular (RR) NON of ER networks with clustering are made up of at least two networks among which exist interdependent relation among whose degree of dependence is measured by coupling strength. We show both analytically and numerically, how the coupling strength and clustering coefficient effect the percolation threshold, size of giant component, critical coupling point where the behavior of phase transition changes from second order to first order with the increase of coupling strength between the networks. Last, we study the two types of clustering network: one type is same with double clustering network in which each subnetwork satisfies ...

  8. Five Differences Between Ecological and Economic Networks

    CERN Document Server

    Smith, Reginald D

    2011-01-01

    Ecological and economic networks have many similarities and are often compared. However, the comparison is often more apt as metaphor than a direct equivalence. In this paper, five key differences are explained which should inform any analysis which compares the two.

  9. Towards an ecological network for the Carpathians

    NARCIS (Netherlands)

    Zingstra, H.L.; Seffer, J.; Lasak, R.; Baltzer, M.; Bouwma, I.M.; Walters, L.J.; Smith, B.; Kitnaes, K.; Predoiu, G.E.; Prots, B.; Sekulic, G.

    2009-01-01

    The Carpathian Biodiversity Information System (CBIS) and the proposal for an ecological network for the eastern part of the Carpathians are the two main outcomes of the project funded by the BBI Matra program of the Dutch government. This brochure presents information on how the CBIS was designed,

  10. Allometry and Dissipation of Ecological Flow Networks

    Science.gov (United States)

    Zhang, Jiang; Wu, Lingfei

    2013-01-01

    Background An ecological flow network is a weighted directed graph in which the nodes are species, the edges are “who eats whom” relationships and the weights are rates of energy or nutrient transferred between species. Allometric scaling is a ubiquitous feature for flow systems such as river basins, vascular networks and food webs. Methodology The “ecological network analysis” can serve to reveal hidden allometries, the power law relationship between the throughflux and the indirect impact of node , directly from the original flow networks without any need to cut edges in the network. The dissipation law, which is another significant scaling relationship between the energy dissipation (respiration) and the throughflow of any species, is also obtained from an analysis of the empirical flow networks. Interestingly, the exponents of the allometric law () and the dissipation law () show a strong relationship for both empirical and simulated flow networks. The dissipation law exponent , rather than the topology of the network, is the most important factors that affect the allometric exponent . Conclusions The exponent can be interpreted as the degree of centralization of the network, i.e., the concentration of impacts (direct and indirect influences on the entire network along all energy flow pathways) on hubs (the nodes with large throughflows). As a result, we find that as increases, the relative energy loss of large nodes increases, decreases, i.e., the relative importance of large species decreases. Moreover, the entire flow network is more decentralized. Therefore, network flow structure (allometry) and thermodynamic constraints (dissipation) are linked. PMID:24019871

  11. The robustness and restoration of a network of ecological networks.

    Science.gov (United States)

    Pocock, Michael J O; Evans, Darren M; Memmott, Jane

    2012-02-24

    Understanding species' interactions and the robustness of interaction networks to species loss is essential to understand the effects of species' declines and extinctions. In most studies, different types of networks (such as food webs, parasitoid webs, seed dispersal networks, and pollination networks) have been studied separately. We sampled such multiple networks simultaneously in an agroecosystem. We show that the networks varied in their robustness; networks including pollinators appeared to be particularly fragile. We show that, overall, networks did not strongly covary in their robustness, which suggests that ecological restoration (for example, through agri-environment schemes) benefitting one functional group will not inevitably benefit others. Some individual plant species were disproportionately well linked to many other species. This type of information can be used in restoration management, because it identifies the plant taxa that can potentially lead to disproportionate gains in biodiversity.

  12. Local Area Networks: Part I.

    Science.gov (United States)

    Dessy, Raymond E.

    1982-01-01

    Local area networks are common communication conduits allowing various terminals, computers, discs, printers, and other electronic devices to intercommunicate over short distances. Discusses the vocabulary of such networks including RS-232C point-to-point and IEEE-488 multidrop protocols; error detection; message packets; multiplexing; star, ring,…

  13. Environmental change makes robust ecological networks fragile

    Science.gov (United States)

    Strona, Giovanni; Lafferty, Kevin D.

    2016-01-01

    Complex ecological networks appear robust to primary extinctions, possibly due to consumers’ tendency to specialize on dependable (available and persistent) resources. However, modifications to the conditions under which the network has evolved might alter resource dependability. Here, we ask whether adaptation to historical conditions can increase community robustness, and whether such robustness can protect communities from collapse when conditions change. Using artificial life simulations, we first evolved digital consumer-resource networks that we subsequently subjected to rapid environmental change. We then investigated how empirical host–parasite networks would respond to historical, random and expected extinction sequences. In both the cases, networks were far more robust to historical conditions than new ones, suggesting that new environmental challenges, as expected under global change, might collapse otherwise robust natural ecosystems.

  14. Imposing early stability to ecological and biological networks through Evolutionary Network Control

    Directory of Open Access Journals (Sweden)

    Alessandro Ferrarini

    2015-03-01

    Full Text Available The stability analysis of the dynamical networks is a well-studied topic, both in ecology and in biology. In this work, I adopt a different perspective: instead of analysing the stability of an arbitrary ecological network, I seek here to impose such stability as soon as possible (or, contrariwise, as late as possible during network dynamics. Evolutionary Network Control (ENC is a theoretical and methodological framework aimed to the control of ecological and biological networks by coupling network dynamics and evolutionary modelling. ENC covers several topics of network control, for instance a the global control from inside and b from outside, c the local (step-by-step control, and the computation of: d control success, e feasibility, and f degree of uncertainty. In this work, I demonstrate that ENC can also be employed to impose early (but, also, late stability to arbitrary ecological and biological networks, and provide an applicative example based on the nonlinear, widely-used, Lotka-Volterra model.

  15. Inferring local ecological processes amid species pool influences

    DEFF Research Database (Denmark)

    Lessard, Jean-Philippe; Belmaker, Jonathan; Myers, Jonathan A.

    2012-01-01

    Resolving contingencies in community ecology requires comparative studies of local communities along broad-scale environmental gradients and in different biogeographic regions. However, comparisons of local ecological processes among regions require a synthetic understanding of how the species pool...... of potential community members influences the structure of ecological communities. Here, we outline an integrative approach for quantifying local ecological processes while explicitly accounting for species pool influences. Specifically, we highlight the utility of combining geographically replicated local...... studies, null models of community structure, and ecologically explicit definitions of the species pool as a means to compare predominant ecological processes among regions. By uniting concepts and tools from community ecology and macroecology, this approach might facilitate synthesis and resolve many...

  16. Inferring local ecological processes amid species pool influences

    DEFF Research Database (Denmark)

    Lessard, Jean-Philippe; Belmaker, Jonathan; Myers, Jonathan A.;

    2012-01-01

    studies, null models of community structure, and ecologically explicit definitions of the species pool as a means to compare predominant ecological processes among regions. By uniting concepts and tools from community ecology and macroecology, this approach might facilitate synthesis and resolve many......Resolving contingencies in community ecology requires comparative studies of local communities along broad-scale environmental gradients and in different biogeographic regions. However, comparisons of local ecological processes among regions require a synthetic understanding of how the species pool...... of potential community members influences the structure of ecological communities. Here, we outline an integrative approach for quantifying local ecological processes while explicitly accounting for species pool influences. Specifically, we highlight the utility of combining geographically replicated local...

  17. Population Cycles, Disease, and Networks of Ecological Knowledge.

    Science.gov (United States)

    Jones, Susan D

    2017-05-01

    Wildlife populations in the northern reaches of the globe have long been observed to fluctuate or cycle periodically, with dramatic increases followed by catastrophic crashes. Focusing on the early work of Charles S. Elton, this article analyzes how investigations into population cycles shaped the development of Anglo-American animal ecology during the 1920s-1930s. Population cycling revealed patterns that challenged ideas about the "balance" of nature; stimulated efforts to quantify population data; and brought animal ecology into conversation with intellectual debates about natural selection. Elton used the problem of understanding wildlife population cycles to explore a central tension in ecological thought: the relative influences of local conditions (food supply, predation) and universal forces (such as climate change and natural selection) in regulating wild animal populations. He also sought patronage and built research practices and the influential Bureau of Animal Population around questions of population regulation during the 1930s. Focusing on disease as a local population regulator that could interact with global climatic influences, Elton facilitated an interdisciplinary and population-based approach in early animal ecology. Elton created a network of epidemiologists, conservationists, pathologists and mathematicians, who contributed to population cycle research. I argue that, although these people often remained peripheral to ecology, their ideas shaped the young discipline. Particularly important were the concepts of abundance, density, and disease; and the interactions between these factors and natural selection. However, Elton's reliance on density dependence unwittingly helped set up conditions conducive to the development of controversies in animal ecology in later years. While ecologists did not come to consensus on the ultimate causes of population cycles, this phenomenon was an important early catalyst for the development of theory and

  18. Local Network Wideband Interconnection Alternatives.

    Science.gov (United States)

    1984-01-01

    greater than 1.5 Mbps and two standard televison channels. 1.1 SCOPE Interconnection of local area networks within the continental United States is...may influence : a. Media selection, b. Interface design, c. The use of the 1.5 Mbps data transmission capacity, and d. Adherence to the full-motion video

  19. Bit by bit control of nonlinear ecological and biological networks using Evolutionary Network Control

    Directory of Open Access Journals (Sweden)

    Alessandro Ferrarini

    2016-06-01

    Full Text Available Evolutionary Network Control (ENC has been first introduced in 2013 to effectively subdue network-like systems. ENC opposes the idea, very common in the scientific literature, that controllability of networks should be based on the identification of the set of driver nodes that can guide the system's dynamics, in other words on the choice of a subset of nodes that should be selected to be permanently controlled. ENC has proven to be effective in the global control (i.e. the focus is on mastery of the final state of network dynamics of linear and nonlinear networks, and in the local (i.e. the focus is on the step-by-step ascendancy of network dynamics control of linear networks. In this work, ENC is applied to the local control of nonlinear networks. Using the Lotka-Volterra model as a case study, I show here that ENC is capable of locally driving nonlinear networks as well, so that also intermediate steps (not only the final state are under our strict control. ENC can be readily applied to any kind of ecological, biological, economic and network-like system.

  20. Preliminary systems engineering evaluations for the National Ecological Observatory Network.

    Energy Technology Data Exchange (ETDEWEB)

    Robertson, Perry J.; Kottenstette, Richard Joseph; Crouch, Shannon M.; Brocato, Robert Wesley; Zak, Bernard Daniel; Osborn, Thor D.; Ivey, Mark D.; Gass, Karl Leslie; Heller, Edwin J.; Dishman, James Larry; Schubert, William Kent; Zirzow, Jeffrey A.

    2008-11-01

    The National Ecological Observatory Network (NEON) is an ambitious National Science Foundation sponsored project intended to accumulate and disseminate ecologically informative sensor data from sites among 20 distinct biomes found within the United States and Puerto Rico over a period of at least 30 years. These data are expected to provide valuable insights into the ecological impacts of climate change, land-use change, and invasive species in these various biomes, and thereby provide a scientific foundation for the decisions of future national, regional, and local policy makers. NEON's objectives are of substantial national and international importance, yet they must be achieved with limited resources. Sandia National Laboratories was therefore contracted to examine four areas of significant systems engineering concern; specifically, alternatives to commercial electrical utility power for remote operations, approaches to data acquisition and local data handling, protocols for secure long-distance data transmission, and processes and procedures for the introduction of new instruments and continuous improvement of the sensor network. The results of these preliminary systems engineering evaluations are presented, with a series of recommendations intended to optimize the efficiency and probability of long-term success for the NEON enterprise.

  1. Non-Hermitian localization in biological networks

    Science.gov (United States)

    Amir, Ariel; Hatano, Naomichi; Nelson, David R.

    2016-04-01

    We explore the spectra and localization properties of the N -site banded one-dimensional non-Hermitian random matrices that arise naturally in sparse neural networks. Approximately equal numbers of random excitatory and inhibitory connections lead to spatially localized eigenfunctions and an intricate eigenvalue spectrum in the complex plane that controls the spontaneous activity and induced response. A finite fraction of the eigenvalues condense onto the real or imaginary axes. For large N , the spectrum has remarkable symmetries not only with respect to reflections across the real and imaginary axes but also with respect to 90∘ rotations, with an unusual anisotropic divergence in the localization length near the origin. When chains with periodic boundary conditions become directed, with a systematic directional bias superimposed on the randomness, a hole centered on the origin opens up in the density-of-states in the complex plane. All states are extended on the rim of this hole, while the localized eigenvalues outside the hole are unchanged. The bias-dependent shape of this hole tracks the bias-independent contours of constant localization length. We treat the large-N limit by a combination of direct numerical diagonalization and using transfer matrices, an approach that allows us to exploit an electrostatic analogy connecting the "charges" embodied in the eigenvalue distribution with the contours of constant localization length. We show that similar results are obtained for more realistic neural networks that obey "Dale's law" (each site is purely excitatory or inhibitory) and conclude with perturbation theory results that describe the limit of large directional bias, when all states are extended. Related problems arise in random ecological networks and in chains of artificial cells with randomly coupled gene expression patterns.

  2. The significance of the Danube ecological corridor in the proceedings of implementing ecological networks in Serbia

    Directory of Open Access Journals (Sweden)

    Filipović Dejan

    2015-01-01

    Full Text Available With the modern processes for exploiting land people have altered the original appearance of areas and created cultural environments. The remaining natural environments, whether protected or not, take up a relatively small portion of space and represent isolated islands which in itself can not be sufficient for the preservation of biodiversity or for the fulfillment of national, regional or international goals and commitments related to their preservation. In order to secure the preservation of biodiversity, the strengthening of integrity and the natural processes, such as animal migrations, succession of vegetation and evolution processes, the communication between natural habitats is imperative. Ecological corridors, as integral elements of ecological networks, ensure the preservation of vital ecological interactions by providing a connection between different habitats or areas. Depending on a range of factors, from the fulfillment of demands of different species to the connecting of regions, corridors of local, sub-regional, regional and international importance are identified. The Danube ecological corridor is one of the most significant corridors of international importance which encompasses a large number of habitats which are part of the natural watercourse of the corridor. There are numerous protected areas in the Danube coastal area on Serbia's territory which present themselves as central areas for forming the ecological network, such as: Gornje Podunavlje, Karađorđevo, Fruška Gora, Titelski Breg hill, Kovalski rit marsh, Dunavski loess bluffs, the Sava mouth, Labudovo okno, Deliblato sands, Đerdap and Mala Vrbica. The diverse and mosaic vegetation of the floodplain, as well as the consistency of the protected areas within the Danube corridor have a direct influence on the quality and functionality of this corridor. The goal of this paper is to show the significance of the Danube ecological corridor in the process of implementing

  3. Wealth networks with local redistribution

    Science.gov (United States)

    Kim, Sunggon; Kim, Gwang Il; Lee, Geymin

    2008-08-01

    We propose a growing network model of the distribution of wealth in a society with local redistribution. Individuals, represented by nodes in the model, provide goods and services to one of their neighbors and they simultaneously produce wealth using goods and services received from their neighbors. A proportion of the wealth produced by a node is redistributed to its neighbors as a reward for the received goods and services. Nodes have different ability to produce wealth. We analyze the interaction between the wealth accumulation process and the structure of the network, and analyze also how the interaction is affected by the redistribution of wealth. It is investigated how rich nodes attract the individuals entering the network in this model. Under a reasonable distribution of ability, simulation result shows that the distribution of degree, i.e. number of neighbors of a node, is scale-free, and that the wealth distribution for the middle class is a log-normal distribution, while for the richest it shows a power-law behavior. We also show that the local redistribution of wealth has a significant effect on the distribution of both degree and wealth.

  4. Personal computer local networks report

    CERN Document Server

    1991-01-01

    Please note this is a Short Discount publication. Since the first microcomputer local networks of the late 1970's and early 80's, personal computer LANs have expanded in popularity, especially since the introduction of IBMs first PC in 1981. The late 1980s has seen a maturing in the industry with only a few vendors maintaining a large share of the market. This report is intended to give the reader a thorough understanding of the technology used to build these systems ... from cable to chips ... to ... protocols to servers. The report also fully defines PC LANs and the marketplace, with in-

  5. Alternative steady states in ecological networks

    Science.gov (United States)

    Fried, Yael; Shnerb, Nadav M.; Kessler, David A.

    2017-07-01

    In many natural situations, one observes a local system with many competing species that is coupled by weak immigration to a regional species pool. The dynamics of such a system is dominated by its stable and uninvadable (SU) states. When the competition matrix is random, the number of SUs depends on the average value and variance of its entries. Here we consider the problem in the limit of weak competition and large variance. Using a yes-no interaction model, we show that the number of SUs corresponds to the number of maximum cliques in an Erdös-Rényi network. The number of SUs grows exponentially with the number of species in this limit, unless the network is completely asymmetric. In the asymmetric limit, the number of SUs is O (1 ) . Numerical simulations suggest that these results are valid for models with a continuous distribution of competition terms.

  6. Disease Localization in Multilayer Networks

    Science.gov (United States)

    de Arruda, Guilherme Ferraz; Cozzo, Emanuele; Peixoto, Tiago P.; Rodrigues, Francisco A.; Moreno, Yamir

    2017-01-01

    We present a continuous formulation of epidemic spreading on multilayer networks using a tensorial representation, extending the models of monoplex networks to this context. We derive analytical expressions for the epidemic threshold of the susceptible-infected-susceptible (SIS) and susceptible-infected-recovered dynamics, as well as upper and lower bounds for the disease prevalence in the steady state for the SIS scenario. Using the quasistationary state method, we numerically show the existence of disease localization and the emergence of two or more susceptibility peaks, which are characterized analytically and numerically through the inverse participation ratio. At variance with what is observed in single-layer networks, we show that disease localization takes place on the layers and not on the nodes of a given layer. Furthermore, when mapping the critical dynamics to an eigenvalue problem, we observe a characteristic transition in the eigenvalue spectra of the supra-contact tensor as a function of the ratio of two spreading rates: If the rate at which the disease spreads within a layer is comparable to the spreading rate across layers, the individual spectra of each layer merge with the coupling between layers. Finally, we report on an interesting phenomenon, the barrier effect; i.e., for a three-layer configuration, when the layer with the lowest eigenvalue is located at the center of the line, it can effectively act as a barrier to the disease. The formalism introduced here provides a unifying mathematical approach to disease contagion in multiplex systems, opening new possibilities for the study of spreading processes.

  7. Large-scale ecological networks do work in an ecologically complex biodiversity hotspot.

    Science.gov (United States)

    Samways, Michael J; Pryke, James S

    2016-03-01

    Landscape-scale ecological networks (ENs) are interconnected conservation corridors of high-quality habitat used to mitigate the adverse effects of landscape fragmentation and to connect with protected areas. The effectiveness of ENs for biodiversity conservation and ecosystem function has been challenged. Here we show how an extensive system of ENs of remnant historic land was put in place at a large spatial scale (>0.5 million ha) in a plantation forestry context in a global biodiversity hotspot in southern Africa. These ENs can maintain indigenous and historic compositional and functional biodiversity, even in an area prone to the challenging effects of El Niño. Furthermore, ENs increase the effective size of local protected areas. Socio-ecological solutions and financial viability are also integrated as part of practical implementation of ENs. By adopting a retrospective analytical approach, biodiversity is maintained while also having productive forestry, making this a powerful agro-ecological approach on a large conservation-significant scale.

  8. Local Area Networks in the School Setting.

    Science.gov (United States)

    Bluhm, Harry P.

    1986-01-01

    Defines local area networks (LANs); describes basic components and configurations of LANs; and discusses LANs benefits (reduced costs, better management of computer resources, enhanced communications) and pitfalls (hidden costs, time delays, network maintenance, lack of standardization, network security breaches, lack of network compatible…

  9. MIGRANT AND LOCAL ENTREPRENEURIAL NETWORKS DEVELOPMENT

    Directory of Open Access Journals (Sweden)

    James D. Adam

    2004-01-01

    Full Text Available This study examines factors influencing migrant and local entrepreneurial business networks with particular reference to Provincial development in Indonesia. Factors of influence include market accessibility, capital accessibility, business focus or business specialisation in manufacturing, trades and services as well as economic conditions, degree of tolerance towards migrant and local entrepreneurs, support networks, business experience, educational background, and entrepreneurial personal characteristics and initiatives. The findings have significance for local development by entrepreneurs in this special case where migrant and local entrepreneurs link in networks and in many cases, joint ventures. The outcomes have significance for government in development programs, academic institutions designing training, and for local business organisation.

  10. New ecological insights through the Global Lake Ecological Observatory Network (GLEON)

    Institute of Scientific and Technical Information of China (English)

    Paul C.Hanson

    2008-01-01

    Sensor networks are playing an increasingly important role in ecology.Continual advances in affordable sensors and wireless communication are making the development of automated sensing systems with remote communication (i.e.,sensor networks) affordable for many ecological research programs (Porter et al.2005)[1].These in situ instruments provide high-frequency data of key variables that previously were measured intermittently and by hand.A number of federal research organizations have realized the potential of environmental sensor networks, and large-scale initiatives are under development.Independent of these initiatives,small sensor networks have emerged to meet the needs of the individual or small teams of ecologists.Ecologists are entering (or already have entered,in some cases) an era in which high temporal and spatial resolution in situ measurements are generating data at unprecedented rates.The use of sensor networks will dramatically increase the volume of ecological data generated in the next decade.

  11. Social-ecological network analysis of scale mismatches in estuary watershed restoration.

    Science.gov (United States)

    Sayles, Jesse S; Baggio, Jacopo A

    2017-03-07

    Resource management boundaries seldom align with environmental systems, which can lead to social and ecological problems. Mapping and analyzing how resource management organizations in different areas collaborate can provide vital information to help overcome such misalignment. Few quantitative approaches exist, however, to analyze social collaborations alongside environmental patterns, especially among local and regional organizations (i.e., in multilevel governance settings). This paper develops and applies such an approach using social-ecological network analysis (SENA), which considers relationships among and between social and ecological units. The framework and methods are shown using an estuary restoration case from Puget Sound, United States. Collaboration patterns and quality are analyzed among local and regional organizations working in hydrologically connected areas. These patterns are correlated with restoration practitioners' assessments of the productivity of their collaborations to inform network theories for natural resource governance. The SENA is also combined with existing ecological data to jointly consider social and ecological restoration concerns. Results show potentially problematic areas in nearshore environments, where collaboration networks measured by density (percentage of possible network connections) and productivity are weakest. Many areas also have high centralization (a few nodes hold the network together), making network cohesion dependent on key organizations. Although centralization and productivity are inversely related, no clear relationship between density and productivity is observed. This research can help practitioners to identify where governance capacity needs strengthening and jointly consider social and ecological concerns. It advances SENA by developing a multilevel approach to assess social-ecological (or social-environmental) misalignments, also known as scale mismatches.

  12. CD-ROM and Local Area Networks.

    Science.gov (United States)

    Marks, Kenneth E.; And Others

    1993-01-01

    This special section on local area networks includes three articles: (1) a description of migration at Joyner Library, East Carolina University (North Carolina) to a new network server; (2) a discussion of factors to consider for network planning in school libraries; and (3) a directory of companies supplying cable, hardware, software, and…

  13. Local Area Networks: Reaping the Benefits.

    Science.gov (United States)

    Raymond, Chadwick; Anderson, Charles

    1987-01-01

    Description of the planning and implementation of a microcomputer-based local area network in the Northbrook (Illinois) Public Library highlights: (1) applying for a grant; (2) network design; (3) the bidding process; (4) installation; (5) implementing the network; and (6) problems and cautions. (MES)

  14. Local Area Networks for Information Retrieval.

    Science.gov (United States)

    Kibirige, Harry M.

    This examination of the use of local area networks (LANs) by libraries summarizes the findings of a nationwide survey of 600 libraries and information centers and 200 microcomputer networking system manufacturers and vendors, which was conducted to determine the relevance of currently available networking systems for library and information center…

  15. CD-ROM and Local Area Networks.

    Science.gov (United States)

    Marks, Kenneth E.; And Others

    1993-01-01

    This special section on local area networks includes three articles: (1) a description of migration at Joyner Library, East Carolina University (North Carolina) to a new network server; (2) a discussion of factors to consider for network planning in school libraries; and (3) a directory of companies supplying cable, hardware, software, and…

  16. Implementation of ecological network in existing conditions of municipal spatial management

    Directory of Open Access Journals (Sweden)

    Pawłat-Zawrzykraj Agata

    2016-12-01

    Full Text Available Contemporary socio-economic development requires a rational and sustainable land management. The pressure for urbanization and building development, existing infrastructural barriers and creation of the new ones, contribute to fragmentation of landscape and thus increase isolation of biologically active areas. Idea of ecological network as a tool for maintaining ecological connectivity is not new and has broad theoretical bases, but implementation of this concept in real-life scenarios is very challenging. The article presents existing formal and legal possibilities of implementing ecological networks, enacted as a part of municipal spatial policy. Differentiated approach to implementation of the idea of ecological connectivity is presented on the example of two suburban municipalities Piaseczno and Góra Kalwaria. Ecological network and especially ecological corridors in these areas have varied status of nature conservation and development of investments is implemented either in accordance with local spatial development plans or, in case of lack of the plans, in accordance with development conditions decision. Analysis of changes in spatial development of the municipalities was used to identify risk areas of losing the ecological connectivity.

  17. Emerging Network-Based Tools in Movement Ecology.

    Science.gov (United States)

    Jacoby, David M P; Freeman, Robin

    2016-04-01

    New technologies have vastly increased the available data on animal movement and behaviour. Consequently, new methods deciphering the spatial and temporal interactions between individuals and their environments are vital. Network analyses offer a powerful suite of tools to disentangle the complexity within these dynamic systems, and we review these tools, their application, and how they have generated new ecological and behavioural insights. We suggest that network theory can be used to model and predict the influence of ecological and environmental parameters on animal movement, focusing on spatial and social connectivity, with fundamental implications for conservation. Refining how we construct and randomise spatial networks at different temporal scales will help to establish network theory as a prominent, hypothesis-generating tool in movement ecology.

  18. Community owned solutions: identifying local best practices for social-ecological sustainability

    Directory of Open Access Journals (Sweden)

    Jayalaxshmi Mistry

    2016-06-01

    Full Text Available Policies and actions that come from higher scale structures, such as international bodies and national governments, are not always compatible with the realities and perspectives of smaller scale units including indigenous communities. Yet, it is at this local social-ecological scale that mechanisms and solutions for dealing with unpredictability and change can be increasingly seen emerging from across the world. Although there is a large body of knowledge specifying the conditions necessary to promote local governance of natural resources, there is a parallel need to develop practical methods for operationalizing the evaluation of local social-ecological systems. In this paper, we report on a systemic, participatory, and visual approach for engaging local communities in an exploration of their own social-ecological system. Working with indigenous communities of the North Rupununi, Guyana, this involved using participatory video and photography within a system viability framework to enable local participants to analyze their own situation by defining indicators of successful strategies that were meaningful to them. Participatory multicriteria analysis was then used to arrive at a short list of best practice strategies. We present six best practices and show how they are intimately linked through the themes of indigenous knowledge, local governance and values, and partnerships and networks. We highlight how developing shared narratives of community owned solutions can help communities to plan governance and management of land and resource systems, while reinforcing sustainable practices by discussing and showcasing them within communities, and by engendering a sense of pride in local solutions.

  19. Wireless Network Coding with Local Network Views: Coded Layer Scheduling

    CERN Document Server

    Vahid, Alireza; Avestimehr, A Salman; Sabharwal, Ashutosh

    2011-01-01

    One of the fundamental challenges in the design of distributed wireless networks is the large dynamic range of network state. Since continuous tracking of global network state at all nodes is practically impossible, nodes can only acquire limited local views of the whole network to design their transmission strategies. In this paper, we study multi-layer wireless networks and assume that each node has only a limited knowledge, namely 1-local view, where each S-D pair has enough information to perform optimally when other pairs do not interfere, along with connectivity information for rest of the network. We investigate the information-theoretic limits of communication with such limited knowledge at the nodes. We develop a novel transmission strategy, namely Coded Layer Scheduling, that solely relies on 1-local view at the nodes and incorporates three different techniques: (1) per layer interference avoidance, (2) repetition coding to allow overhearing of the interference, and (3) network coding to allow inter...

  20. Inference of Gene Regulatory Network Based on Local Bayesian Networks.

    Science.gov (United States)

    Liu, Fei; Zhang, Shao-Wu; Guo, Wei-Feng; Wei, Ze-Gang; Chen, Luonan

    2016-08-01

    The inference of gene regulatory networks (GRNs) from expression data can mine the direct regulations among genes and gain deep insights into biological processes at a network level. During past decades, numerous computational approaches have been introduced for inferring the GRNs. However, many of them still suffer from various problems, e.g., Bayesian network (BN) methods cannot handle large-scale networks due to their high computational complexity, while information theory-based methods cannot identify the directions of regulatory interactions and also suffer from false positive/negative problems. To overcome the limitations, in this work we present a novel algorithm, namely local Bayesian network (LBN), to infer GRNs from gene expression data by using the network decomposition strategy and false-positive edge elimination scheme. Specifically, LBN algorithm first uses conditional mutual information (CMI) to construct an initial network or GRN, which is decomposed into a number of local networks or GRNs. Then, BN method is employed to generate a series of local BNs by selecting the k-nearest neighbors of each gene as its candidate regulatory genes, which significantly reduces the exponential search space from all possible GRN structures. Integrating these local BNs forms a tentative network or GRN by performing CMI, which reduces redundant regulations in the GRN and thus alleviates the false positive problem. The final network or GRN can be obtained by iteratively performing CMI and local BN on the tentative network. In the iterative process, the false or redundant regulations are gradually removed. When tested on the benchmark GRN datasets from DREAM challenge as well as the SOS DNA repair network in E.coli, our results suggest that LBN outperforms other state-of-the-art methods (ARACNE, GENIE3 and NARROMI) significantly, with more accurate and robust performance. In particular, the decomposition strategy with local Bayesian networks not only effectively reduce

  1. Distinct types of eigenvector localization in networks

    CERN Document Server

    Pastor-Satorras, Romualdo

    2016-01-01

    The spectral properties of the adjacency matrix provide a trove of information about the structure and function of complex networks. In particular, the largest eigenvalue and its associated principal eigenvector are crucial in the understanding of node's centrality and the unfolding of dynamical processes. Here we show that two distinct types of localization of the principal eigenvector may occur in heterogeneous networks. For synthetic networks with degree distribution $P(q) \\sim q^{-\\gamma}$, localization occurs on the largest hub if $\\gamma>5/2$; for $\\gamma<5/2$ a new type of localization arises on a mesoscopic subgraph associated to the shell with the largest index in the $K$-core decomposition. Similar evidence for the existence of distinct localization modes is found in the analysis of real-world networks. Our results open a new perspective on dynamical processes on networks and on a recently proposed alternative measure of node centrality based on the non-backtracking matrix.

  2. Percolation of localized attack on complex networks

    CERN Document Server

    Shao, Shuai; Stanley, H Eugene; Havlin, Shlomo

    2014-01-01

    The robustness of complex networks against node failure and malicious attack has been of interest for decades, while most of the research has focused on random attack or hub-targeted attack. In many real-world scenarios, however, attacks are neither random nor hub-targeted, but localized, where a group of neighboring nodes in a network are attacked and fail. In this paper we develop a percolation framework to analytically and numerically study the robustness of complex networks against such localized attack. In particular, we investigate this robustness in Erd\\H{o}s-R\\'{e}nyi networks, random-regular networks, and scale-free networks. Our results provide insight into how to better protect networks, enhance cybersecurity, and facilitate the design of more robust infrastructures.

  3. Connectivity and Nestedness in Bipartite Networks from Community Ecology

    Energy Technology Data Exchange (ETDEWEB)

    Corso, Gilberto [Departamento de Biofisica e Farmacologia, Centro de Biociencias, Universidade Federal do Rio Grande do Norte, UFRN - Campus Universitario, Lagoa Nova, CEP 59078 972, Natal, RN (Brazil); De Araujo, A I Levartoski [Instituto Federal de Educacao, Ciencia e Tecnologia do Ceara Av. Treze de Maio, 2081 - Benfica CEP 60040-531 - Fortaleza, CE (Brazil); De Almeida, Adriana M, E-mail: corso@cb.ufrn.br [Departamento de Botanica, Ecologia e Zoologia, Centro de Biociencias, Universidade Federal do Rio Grande do Norte, UFRN - Campus Universitario, Lagoa Nova, CEP 59078 972, Natal, RN (Brazil)

    2011-03-01

    Bipartite networks and the nestedness concept appear in two different contexts in theoretical ecology: community ecology and islands biogeography. From a mathematical perspective nestedness is a pattern in a bipartite network. There are several nestedness indices in the market, we used the index {nu}. The index {nu} is found using the relation {nu} = 1 - {tau} where {tau} is the temperature of the adjacency matrix of the bipartite network. By its turn {tau} is defined with help of the Manhattan distance of the occupied elements of the adjacency matrix of the bipartite network. We prove that the nestedness index {nu} is a function of the connectivities of the bipartite network. In addition we find a concise way to find {nu} which avoid cumbersome algorithm manupulation of the adjacency matrix.

  4. Designing Industrial Networks Using Ecological Food Web Metrics.

    Science.gov (United States)

    Layton, Astrid; Bras, Bert; Weissburg, Marc

    2016-10-18

    Biologically Inspired Design (biomimicry) and Industrial Ecology both look to natural systems to enhance the sustainability and performance of engineered products, systems and industries. Bioinspired design (BID) traditionally has focused on a unit operation and single product level. In contrast, this paper describes how principles of network organization derived from analysis of ecosystem properties can be applied to industrial system networks. Specifically, this paper examines the applicability of particular food web matrix properties as design rules for economically and biologically sustainable industrial networks, using an optimization model developed for a carpet recycling network. Carpet recycling network designs based on traditional cost and emissions based optimization are compared to designs obtained using optimizations based solely on ecological food web metrics. The analysis suggests that networks optimized using food web metrics also were superior from a traditional cost and emissions perspective; correlations between optimization using ecological metrics and traditional optimization ranged generally from 0.70 to 0.96, with flow-based metrics being superior to structural parameters. Four structural food parameters provided correlations nearly the same as that obtained using all structural parameters, but individual structural parameters provided much less satisfactory correlations. The analysis indicates that bioinspired design principles from ecosystems can lead to both environmentally and economically sustainable industrial resource networks, and represent guidelines for designing sustainable industry networks.

  5. Local Natural Connectivity in Complex Networks

    Institute of Scientific and Technical Information of China (English)

    SHANG Yi-Lun

    2011-01-01

    @@ In network theory, a complex network represents a system whose evolving structure and dynamic behavior contribute to its robustness.The natural connectivity is recently proposed as a spectral measure to characterize the robustness of complex networks.We decompose the natural connectivity of a network as local natural connectivity of its connected components and quantify their contributions to the network robustness.In addition, we compare the natural connectivity of a network with that of an induced subgraph of it based on interlacing theorems.As an application, we derive an inequality for eigenvalues of ErdSs-Renyi random graphs.%In network theory, a complex network represents a system whose evolving structure and dynamic behavior contribute to its robustness. The natural connectivity is recently proposed as a spectral measure to characterize the robustness of complex networks. We decompose the natural connectivity of a network as local naturai connectivity of its connected components and quantify their contributions to the network robustness. In addition, we compare the naturai connectivity of a network with that of an induced subgraph of it based on interlacing theorems. As an application, we derive an inequality for eigenvalues of Erdos-Renyi random graphs.

  6. Social network models predict movement and connectivity in ecological landscapes

    Science.gov (United States)

    Fletcher, Robert J.; Acevedo, M.A.; Reichert, Brian E.; Pias, Kyle E.; Kitchens, Wiley M.

    2011-01-01

    Network analysis is on the rise across scientific disciplines because of its ability to reveal complex, and often emergent, patterns and dynamics. Nonetheless, a growing concern in network analysis is the use of limited data for constructing networks. This concern is strikingly relevant to ecology and conservation biology, where network analysis is used to infer connectivity across landscapes. In this context, movement among patches is the crucial parameter for interpreting connectivity but because of the difficulty of collecting reliable movement data, most network analysis proceeds with only indirect information on movement across landscapes rather than using observed movement to construct networks. Statistical models developed for social networks provide promising alternatives for landscape network construction because they can leverage limited movement information to predict linkages. Using two mark-recapture datasets on individual movement and connectivity across landscapes, we test whether commonly used network constructions for interpreting connectivity can predict actual linkages and network structure, and we contrast these approaches to social network models. We find that currently applied network constructions for assessing connectivity consistently, and substantially, overpredict actual connectivity, resulting in considerable overestimation of metapopulation lifetime. Furthermore, social network models provide accurate predictions of network structure, and can do so with remarkably limited data on movement. Social network models offer a flexible and powerful way for not only understanding the factors influencing connectivity but also for providing more reliable estimates of connectivity and metapopulation persistence in the face of limited data.

  7. Law of localization in chemical reaction networks

    CERN Document Server

    Okada, Takashi

    2016-01-01

    In living cells, chemical reactions are connected by sharing their products and substrates, and form complex networks, e.g. metabolic pathways. Here we developed a theory to predict the sensitivity, i.e. the responses of concentrations and fluxes to perturbations of enzymes, from network structure alone. Responses turn out to exhibit two characteristic patterns, $localization$ and $hierarchy$. We present a general theorem connecting sensitivity with network topology that explains these characteristic patterns. Our results imply that network topology is an origin of biological robustness. Finally, we suggest a strategy to determine real networks from experimental measurements.

  8. Protecting information on local area networks

    CERN Document Server

    Schweitzer, James A

    1988-01-01

    Protecting Information on Local Area Networks presents the various types of networks and explains why they are being expanded at such a rapid pace. This book considers how management can gain control of the valuable network-services information resources generally available.Organized into three parts encompassing seven chapters, this book begins with an overview of the various networks and their operations. This text then discusses the appropriate management actions to ensure some control over the use of networks and the business information resource. Other chapters consider the management rat

  9. Functional Extinctions of Species in Ecological Networks

    OpenAIRE

    Säterberg, Torbjörn

    2016-01-01

    Current rates of extinctions are estimated to be around 1000 times higher than background rates that would occur without anthropogenic impacts. These extinction rates refer to the traditional view of extinctions, i.e. numerical extinctions. This thesis is about another type of extinctions: functional extinctions. Those occur when the abundance of a species is too small to uphold the species’ ecologically interactive role. I have taken a theoretical approach and used dynamical models to invest...

  10. Plant Insecticidal Toxins in Ecological Networks

    Directory of Open Access Journals (Sweden)

    Sébastien Ibanez

    2012-04-01

    Full Text Available Plant secondary metabolites play a key role in plant-insect interactions, whether constitutive or induced, C- or N-based. Anti-herbivore defences against insects can act as repellents, deterrents, growth inhibitors or cause direct mortality. In turn, insects have evolved a variety of strategies to act against plant toxins, e.g., avoidance, excretion, sequestration and degradation of the toxin, eventually leading to a co-evolutionary arms race between insects and plants and to co-diversification. Anti-herbivore defences also negatively impact mutualistic partners, possibly leading to an ecological cost of toxin production. However, in other cases toxins can also be used by plants involved in mutualistic interactions to exclude inadequate partners and to modify the cost/benefit ratio of mutualism to their advantage. When considering the whole community, toxins have an effect at many trophic levels. Aposematic insects sequester toxins to defend themselves against predators. Depending on the ecological context, toxins can either increase insects’ vulnerability to parasitoids and entomopathogens or protect them, eventually leading to self-medication. We conclude that studying the community-level impacts of plant toxins can provide new insights into the synthesis between community and evolutionary ecology.

  11. Plant insecticidal toxins in ecological networks.

    Science.gov (United States)

    Ibanez, Sébastien; Gallet, Christiane; Després, Laurence

    2012-04-01

    Plant secondary metabolites play a key role in plant-insect interactions, whether constitutive or induced, C- or N-based. Anti-herbivore defences against insects can act as repellents, deterrents, growth inhibitors or cause direct mortality. In turn, insects have evolved a variety of strategies to act against plant toxins, e.g., avoidance, excretion, sequestration and degradation of the toxin, eventually leading to a co-evolutionary arms race between insects and plants and to co-diversification. Anti-herbivore defences also negatively impact mutualistic partners, possibly leading to an ecological cost of toxin production. However, in other cases toxins can also be used by plants involved in mutualistic interactions to exclude inadequate partners and to modify the cost/benefit ratio of mutualism to their advantage. When considering the whole community, toxins have an effect at many trophic levels. Aposematic insects sequester toxins to defend themselves against predators. Depending on the ecological context, toxins can either increase insects' vulnerability to parasitoids and entomopathogens or protect them, eventually leading to self-medication. We conclude that studying the community-level impacts of plant toxins can provide new insights into the synthesis between community and evolutionary ecology.

  12. Local Area Networks and Classroom Anarchy.

    Science.gov (United States)

    Stanley, Ron

    1992-01-01

    Explores the use of local area networks (LAN's) in learning laboratories and how they are improving learning outcomes for certain student populations (e.g., deaf and developmental students). Describes how LAN's alter the instructor's role and how instructors can manage student-driven classrooms. Offers guidance on implementing a network system.…

  13. A Global Lake Ecological Observatory Network (GLEON) for synthesising high-frequency sensor data for validation of deterministic ecological models

    Science.gov (United States)

    David, Hamilton P; Carey, Cayelan C.; Arvola, Lauri; Arzberger, Peter; Brewer, Carol A.; Cole, Jon J; Gaiser, Evelyn; Hanson, Paul C.; Ibelings, Bas W; Jennings, Eleanor; Kratz, Tim K; Lin, Fang-Pang; McBride, Christopher G.; de Motta Marques, David; Muraoka, Kohji; Nishri, Ami; Qin, Boqiang; Read, Jordan S.; Rose, Kevin C.; Ryder, Elizabeth; Weathers, Kathleen C.; Zhu, Guangwei; Trolle, Dennis; Brookes, Justin D

    2014-01-01

    A Global Lake Ecological Observatory Network (GLEON; www.gleon.org) has formed to provide a coordinated response to the need for scientific understanding of lake processes, utilising technological advances available from autonomous sensors. The organisation embraces a grassroots approach to engage researchers from varying disciplines, sites spanning geographic and ecological gradients, and novel sensor and cyberinfrastructure to synthesise high-frequency lake data at scales ranging from local to global. The high-frequency data provide a platform to rigorously validate process- based ecological models because model simulation time steps are better aligned with sensor measurements than with lower-frequency, manual samples. Two case studies from Trout Bog, Wisconsin, USA, and Lake Rotoehu, North Island, New Zealand, are presented to demonstrate that in the past, ecological model outputs (e.g., temperature, chlorophyll) have been relatively poorly validated based on a limited number of directly comparable measurements, both in time and space. The case studies demonstrate some of the difficulties of mapping sensor measurements directly to model state variable outputs as well as the opportunities to use deviations between sensor measurements and model simulations to better inform process understanding. Well-validated ecological models provide a mechanism to extrapolate high-frequency sensor data in space and time, thereby potentially creating a fully 3-dimensional simulation of key variables of interest.

  14. Citizen Involvement in Local Security Networks

    NARCIS (Netherlands)

    Terpstra, J.B.

    2009-01-01

    This paper deals with the involvement of citizens (and local businesspersons) in the prevention and control of crime and disorder. Four models of citizen involvement in local security networks are distinguished. In each of these models the role of citizens concentrates on different functions: (1) p

  15. Social-ecology networks : building connections for sustainable landscapes

    NARCIS (Netherlands)

    Opdam, P.F.M.

    2014-01-01

    Humans adapt their landscapes, their living environment. Sustainable use of the various landscape benefits requires that land owners and users collaborate in managing ecological networks. Because the government is stepping back as the organizer of coordinated landscape adaptation, we need new landsc

  16. Corridors for LIFE; ecological network analysis for Cheshire County (UK)

    NARCIS (Netherlands)

    Sluis, van der T.; Bunce, R.G.H.; Kuipers, H.; Dirksen, J.

    2003-01-01

    This report gives the result of an analysis of the ecological network, designed for the agricultural plains of Cheshire. Five ecosystem types were selected: meres and mosses, heathland, wetland and rivers, woodland, and grassland,. Species were selected which can be considered representative for the

  17. Social-ecology networks : building connections for sustainable landscapes

    NARCIS (Netherlands)

    Opdam, P.F.M.

    2014-01-01

    Humans adapt their landscapes, their living environment. Sustainable use of the various landscape benefits requires that land owners and users collaborate in managing ecological networks. Because the government is stepping back as the organizer of coordinated landscape adaptation, we need new landsc

  18. Towards 'ecological coherence': Assessing larval dispersal within a network of existing Marine Protected Areas

    Science.gov (United States)

    Ross, Rebecca E.; Nimmo-Smith, W. Alex M.; Howell, Kerry L.

    2017-08-01

    The Convention on Biological Diversity mandates the establishment of Marine Protected Area (MPA) networks worldwide, with recommendations stating the importance of 'ecological coherence,' a responsibility to support and perpetuate the existing ecosystem, implying the need to sustain population connectivity. While recommendations exist for integrating connectivity data into MPA planning, little advice exists on how to assess the connectivity of existing networks. This study makes use of recently observed larval characteristics and freely available models to demonstrate how such an assessment could be undertaken. The cold water coral (CWC) Lophelia pertusa (Linnaeus, 1758) is used as a model species, as much of the NE Atlantic MPA network has been designated for CWC reef protection, but the ecological coherence of the network has yet to be assessed. Simulations are run for different behavioural null models allowing a comparison of 'passive' (current driven) and 'active' (currents + vertical migration) dispersal, while an average prediction is used for MPA assessment. This model suggests that the network may support widespread larval exchange and has good local retention rates but still has room for improvement. The best performing MPAs were large and central to the network facilitating transport across local dispersal barriers. On average, passive and active dispersal simulations gave statistically similar results, providing encouragement to future local dispersal assessments where active characteristics are unknown.

  19. Localized recovery of complex networks against failure

    Science.gov (United States)

    Shang, Yilun

    2016-07-01

    Resilience of complex networks to failure has been an important issue in network research for decades, and recent studies have begun to focus on the inverse recovery of network functionality through strategically healing missing nodes or edges. However, the effect of network recovery is far from fully understood, and a general theory is still missing. Here we propose and study a general model of localized recovery, where a group of neighboring nodes are restored in an invasive way from a seed node. We develop a theoretical framework to compare the effect of random recovery (RR) and localized recovery (LR) in complex networks including Erdős-Rényi networks, random regular networks, and scale-free networks. We find detailed phase diagrams for the subnetwork of occupied nodes and the “complement network” of failed nodes under RR and LR. By identifying the two competitive forces behind LR, we present an analytical and numerical approach to guide us in choosing the appropriate recovery strategy and provide estimation on its effect by using the degree distribution of the original network as the only input. Our work therefore provides insight for quantitatively understanding recovery process and its implications in infrastructure protection in various complex systems.

  20. Cooperative Localization for Mobile Networks

    DEFF Research Database (Denmark)

    Cakmak, Burak; Urup, Daniel Nygaard; Meyer, Florian;

    2016-01-01

    We propose a hybrid message passing method for distributed cooperative localization and tracking of mobile agents. Belief propagation and mean field message passing are employed for, respectively, the motion-related and measurementrelated part of the factor graph. Using a Gaussian belief approxim...... approximation, only three real values per message passing iteration have to be broadcast to neighboring agents. Despite these very low communication requirements, the estimation accuracy can be comparable to that of particle-based belief propagation....

  1. Inference of Gene Regulatory Network Based on Local Bayesian Networks.

    Directory of Open Access Journals (Sweden)

    Fei Liu

    2016-08-01

    Full Text Available The inference of gene regulatory networks (GRNs from expression data can mine the direct regulations among genes and gain deep insights into biological processes at a network level. During past decades, numerous computational approaches have been introduced for inferring the GRNs. However, many of them still suffer from various problems, e.g., Bayesian network (BN methods cannot handle large-scale networks due to their high computational complexity, while information theory-based methods cannot identify the directions of regulatory interactions and also suffer from false positive/negative problems. To overcome the limitations, in this work we present a novel algorithm, namely local Bayesian network (LBN, to infer GRNs from gene expression data by using the network decomposition strategy and false-positive edge elimination scheme. Specifically, LBN algorithm first uses conditional mutual information (CMI to construct an initial network or GRN, which is decomposed into a number of local networks or GRNs. Then, BN method is employed to generate a series of local BNs by selecting the k-nearest neighbors of each gene as its candidate regulatory genes, which significantly reduces the exponential search space from all possible GRN structures. Integrating these local BNs forms a tentative network or GRN by performing CMI, which reduces redundant regulations in the GRN and thus alleviates the false positive problem. The final network or GRN can be obtained by iteratively performing CMI and local BN on the tentative network. In the iterative process, the false or redundant regulations are gradually removed. When tested on the benchmark GRN datasets from DREAM challenge as well as the SOS DNA repair network in E.coli, our results suggest that LBN outperforms other state-of-the-art methods (ARACNE, GENIE3 and NARROMI significantly, with more accurate and robust performance. In particular, the decomposition strategy with local Bayesian networks not only

  2. Ecological interaction and phylogeny, studying functionality on composed networks

    Science.gov (United States)

    Cruz, Claudia P. T.; Fonseca, Carlos Roberto; Corso, Gilberto

    2012-02-01

    We study a class of composed networks that are formed by two tree networks, TP and TA, whose end points touch each other through a bipartite network BPA. We explore this network using a functional approach. We are interested in how much the topology, or the structure, of TX (X=A or P) determines the links of BPA. This composed structure is a useful model in evolutionary biology, where TP and TA are the phylogenetic trees of plants and animals that interact in an ecological community. We make use of ecological networks of dispersion of fruits, which are formed by frugivorous animals and plants with fruits; the animals, usually birds, eat fruits and disperse their seeds. We analyse how the phylogeny of TX determines or is correlated with BPA using a Monte Carlo approach. We use the phylogenetic distance among elements that interact with a given species to construct an index κ that quantifies the influence of TX over BPA. The algorithm is based on the assumption that interaction matrices that follows a phylogeny of TX have a total phylogenetic distance smaller than the average distance of an ensemble of Monte Carlo realisations. We find that the effect of phylogeny of animal species is more pronounced in the ecological matrix than plant phylogeny.

  3. Functional Localization of Genetic Network Programming

    Science.gov (United States)

    Eto, Shinji; Hirasawa, Kotaro; Hu, Jinglu

    According to the knowledge of brain science, it is suggested that there exists cerebral functional localization, which means that a specific part of the cerebrum is activated depending on various kinds of information human receives. The aim of this paper is to build an artificial model to realize functional localization based on Genetic Network Programming (GNP), a new evolutionary computation method recently developed. GNP has a directed graph structure suitable for realizing functional localization. We studied the basic characteristics of the proposed system by making GNP work in a functionally localized way.

  4. Landscape Planning and Ecological Networks. Part A. A Rural System in Nuoro, Sardinia

    Directory of Open Access Journals (Sweden)

    Andrea De Montis

    2014-05-01

    Full Text Available Urban-rural landscape planning research is nowadays focusing on strategies and tools that support practitioners in designing integrated spaces starting from the analysis of local areas, where human and natural pressures interfere. A prominent framework is provided by the ecological networks, whose design regards the combination of a set of green areas or patches (the nodes interconnected through environmental corridors (the edges. Ecological networks are useful for biodiversity protection and enhancement, as they are able to counteract fragmentation, and to create or strengthen relations and exchanges among otherwise isolated elements. Biodiversity evolution, indeed, depends on the quantity and quality of spatial cohesion of natural areas.  In this paper, we aim at designing an ecological network for the periurban area on the town of Nuoro in central Sardinia. The narrative unfolds in two parts. Part A is presented in this paper and includes its methodological premises, i.e. biodiversity conservation and ecological network analysis and design, and the introductory elements of a spatial analysis on a pilot ecological network of one hundred patches. We locate patches by focusing on the ecosystems supported by the target vegetal species holm oak (Quercus ilex and cultivated or wild olive (Olea europaea var. sativa, O. europaea var. sylverstis. These are very common plants species in the municipality and some animal species are active as seed dispersal. The reminder, i.e. Part B, of the essay is presented in an homonymous paper that focuses on the illustration of the network analysis conceived as a monitoring system and, in future perspective, as a planning support system.

  5. Metastable Localization of Diseases in Complex Networks

    CERN Document Server

    Ferreira, R S; Dorogovtsev, S N; Mendes, J F F

    2016-01-01

    We describe the phenomenon of localization in the epidemic SIS model on highly heterogeneous networks in which strongly connected nodes (hubs) play the role of centers of localization. We find that in this model the localized states below the epidemic threshold are metastable. The longevity and scale of the metastable outbreaks do not show a sharp localization transition, instead there is a smooth crossover from localized to delocalized states as we approach the epidemic threshold from below. Analyzing these long-lasting local outbreaks for a regular random graph (Bethe lattice) with a hub, we show how this localization can be detected from the shape of the distribution of the number of infective nodes.

  6. Decentralized control of ecological and biological networks through Evolutionary Network Control

    Directory of Open Access Journals (Sweden)

    Alessandro Ferrarini

    2016-09-01

    Full Text Available Evolutionary Network Control (ENC has been recently introduced to allow the control of any kind of ecological and biological networks, with an arbitrary number of nodes and links, acting from inside and/or outside. To date, ENC has been applied using a centralized approach where an arbitrary number of network nodes and links could be tamed. This approach has shown to be effective in the control of ecological and biological networks. However a decentralized control, where only one node and the correspondent input/output links are controlled, could be more economic from a computational viewpoint, in particular when the network is very large (i.e. big data. In this view, ENC is upgraded here to realize the decentralized control of ecological and biological nets.

  7. Common Organizing Mechanisms in Ecological and Socio-economic Networks

    CERN Document Server

    Saavedra, Serguei; Uzzi, Brian

    2011-01-01

    Previous work has shown that species interacting in an ecosystem and actors transacting in an economic context may have notable similarities in behavior. However, the specific mechanism that may underlie similarities in nature and human systems has not been analyzed. Building on stochastic food-web models, we propose a parsimonious bipartite-cooperation model that reproduces the key features of mutualistic networks - degree distribution, nestedness and modularity -- for both ecological networks and socio-economic networks. Our analysis uses two diverse networks. Mutually-beneficial interactions between plants and their pollinators, and cooperative economic exchanges between designers and their contractors. We find that these mutualistic networks share a key hierarchical ordering of their members, along with an exponential constraint in the number and type of partners they can cooperate with. We use our model to show that slight changes in the interaction constraints can produce either extremely nested or rand...

  8. The Security of Wireless Local Area Network

    Institute of Scientific and Technical Information of China (English)

    林楠; 李翠霞

    2007-01-01

    The Wireless Local Area Network (WLAN) is a new and developing technology and the security problem is always important in all networks; therefore, the security problems will be discussed in this article. The article firstly introduces the history of development of IEEE 802.11 and provides an overview of the Wireless LAN. The architecture of WLAN will be referred in next. Finally, the further of the wireless LAN will be prospected by this article.

  9. Smart social adaptation prevents catastrophic ecological regime shifts in networks of myopic harvesters

    Science.gov (United States)

    Donges, Jonathan; Lucht, Wolfgang; Wiedermann, Marc; Heitzig, Jobst; Kurths, Jürgen

    2015-04-01

    In the anthropocene, the rise of global social and economic networks with ever increasing connectivity and speed of interactions, e.g., the internet or global financial markets, is a key challenge for sustainable development. The spread of opinions, values or technologies on these networks, in conjunction with the coevolution of the network structures themselves, underlies nexuses of current concern such as anthropogenic climate change, biodiversity loss or global land use change. To isolate and quantitatively study the effects and implications of network dynamics for sustainable development, we propose an agent-based model of information flow on adaptive networks between myopic harvesters that exploit private renewable resources. In this conceptual model of a network of socio-ecological systems, information on management practices flows between agents via boundedly rational imitation depending on the state of the resource stocks involved in an interaction. Agents can also adapt the structure of their social network locally by preferentially connecting to culturally similar agents with identical management practices and, at the same time, disconnecting from culturally dissimilar agents. Investigating in detail the statistical mechanics of this model, we find that an increasing rate of information flow through faster imitation dynamics or growing density of network connectivity leads to a marked increase in the likelihood of environmental resource collapse. However, we show that an optimal rate of social network adaptation can mitigate this negative effect without loss of social cohesion through network fragmentation. Our results highlight that seemingly immaterial network dynamics of spreading opinions or values can be of large relevance for the sustainable management of socio-ecological systems and suggest smartly conservative network adaptation as a strategy for mitigating environmental collapse. Hence, facing the great acceleration, these network dynamics should

  10. Emerging localized food networks in Denmark

    DEFF Research Database (Denmark)

    Kristensen, Niels Heine; Hansen, Mette Weinreich

    2012-01-01

    One of the fastest growing food related social movements are citizen driven food networks. The Danish initiatives emerged in Copenhagen from an open culinary, social, environmental and organic oriented network. The theories and strategies of the original initiative is presented in this paper......, together with an analysis of how this has evolved and expanded. The challenges this rapid expansion puts on the internal network and organisation, and on the local food supplieres - the organic farmers - are elaborated in this paper. Also – from a rural sociology perspective – the interaction...

  11. Emerging localized food networks in Denmark

    DEFF Research Database (Denmark)

    Kristensen, Niels Heine; Hansen, Mette Weinreich

    2012-01-01

    One of the fastest growing food related social movements are citizen driven food networks. The Danish initiatives emerged in Copenhagen from an open culinary, social, environmental and organic oriented network. The theories and strategies of the original initiative is presented in this paper......, together with an analysis of how this has evolved and expanded. The challenges this rapid expansion puts on the internal network and organisation, and on the local food supplieres - the organic farmers - are elaborated in this paper. Also – from a rural sociology perspective – the interaction...

  12. Local Area Network Management: An Unresolved Issue.

    Science.gov (United States)

    Howden, Norman

    1989-01-01

    Discussion of management issues involved with local area networks (LAN) among information organizations focuses on a project at the University of North Texas that was designed to investigate problems associated with LAN. Topics discussed include purchasing decisions for hardware and software, and integration among various groups of users. (Eight…

  13. Wireless Laptops and Local Area Networks.

    Science.gov (United States)

    Tolson, Stephanie Diane

    2001-01-01

    Describes experiences at St. Louis Community College at Florissant Valley (Missouri) with the use of wireless technology and a local area network for library bibliographic instruction. Discusses faculty input and attitudes; technical challenges; and experiences at other community colleges that have found wireless connections more economical than…

  14. Local Area Networks--For Your Library?

    Science.gov (United States)

    Leggott, Mark

    1989-01-01

    Describes a typical configuration for a local area network (LAN), and discusses positive and negative factors to be considered when deciding whether to implement a LAN in a library setting. Situations in which LANS are or are not appropriate are identified, and alternatives to LANs are described. (CLB)

  15. On local optima in learning bayesian networks

    DEFF Research Database (Denmark)

    Dalgaard, Jens; Kocka, Tomas; Pena, Jose

    2003-01-01

    This paper proposes and evaluates the k-greedy equivalence search algorithm (KES) for learning Bayesian networks (BNs) from complete data. The main characteristic of KES is that it allows a trade-off between greediness and randomness, thus exploring different good local optima. When greediness...

  16. Sensor Network Localization with Imprecise Distances

    NARCIS (Netherlands)

    Cao, M.; Morse, A.S.; Anderson, B.D.O.

    2006-01-01

    An approach to formulate geometric relations among distances between nodes as equality constraints is introduced in this paper to study the localization problem with imprecise distance information in sensor networks. These constraints can be further used to formulate optimization problems for distan

  17. Peer effects and local congestion in networks

    NARCIS (Netherlands)

    Currarini, Sergio; Fumagalli, E.; Panebianco, Fabrizio

    We study linear quadratic games played on a network. Agents face peer effects with distance-one neighbors, and strategic substitution with distance-two neighbors (local congestion). For this class of games, we show that an interior equilibrium exists both in the high and in the low regions of the

  18. Ecology 2.0: Coexistence and Domination of Interacting Networks

    CERN Document Server

    Kleineberg, Kaj-Kolja

    2014-01-01

    The overwhelming success of the web 2.0, with online social networks as key actors, has induced a paradigm shift in the nature of human interactions. The user-driven character of these services for the first time has allowed researchers to quantify large-scale social patterns. However, the mechanisms that determine the fate of networks at a system level are still poorly understood. For instance, the simultaneous existence of numerous digital services naturally raises the question under which conditions these services can coexist. In analogy to population dynamics, the digital world is forming a complex ecosystem of interacting networks whose fitnesses depend on their ability to attract and maintain users' attention, which constitutes a limited resource. In this paper, we introduce an ecological theory of the digital world which exhibits a stable coexistence of several networks as well as the domination of a single one, in contrast to the principle of competitive exclusion. Interestingly, our model also predic...

  19. INTERFERENCES BETWEEN THE ECOLOGICAL NETWORK AND URBANIZED AREAS IN POLAND

    Directory of Open Access Journals (Sweden)

    IWONA ZWIERZCHOWSKA

    2008-06-01

    Full Text Available This paper presents spatial relations between Polish urban areas and valuable habitats and links between them composing the country’s ecological network. The quantitative analysis for 891 towns and cities was conducted using GIS techniques based on cartographic vector data and statistical data. Valuable habitats and links between them, such as national parks, landscape parks, CORINE biotopes sites, wildlife corridors linking NATURA 2000 sites and ECONET areas, can be found in 72% of Polish towns and cities. The proportion of artificial surfaces in those areas is different depending on the size of a town or city and its location. Urban areas with the highest index of presence of valuable habitats and links between them are concentrated in the south of Poland, where settlement network is most dense. However, in the case of those areas the proportion of artificial surfaces interfering with the ecological network is lower than Poland’s average, being 16%. The pressure of anthropogenic land cover extending onto the country’s ecological network is most conspicuous in urban areas with a population of at least several dozen thousand residents where the average developed area is 20.8% of their total area. The danger for the continuity of the nature system is best seen in the north westernPoland, where artificial surfaces interference in towns and cities is largest. The analysis performed identified 82 towns and cities, in which the preservation of the continuity of the ecological networkshould be a priority in spatial management because of a higher than average index of the presence of valuable habitats and links between them and large proportion of artificial surfaces in those areas.

  20. Local Area Network Performance Using UML

    Directory of Open Access Journals (Sweden)

    Dr Vipin Saxena

    2010-09-01

    Full Text Available This paper explains the performance of LAN/WAN using UML. Nowadays, Local Area Network (LAN System is an integral part of any organization. This may established by the use of the fiber optics cables or through Wi-Fi connectivity called as Wireless Local Area Network (WLAN. In the network connectivity, administrator has to ensure whether the destination node is receiving the data correctly, safely and within minimum time period. In the country, many of the organizations have the LAN or WLAN but one has to check the performance of these, therefore, in this paper, performance of LAN/WLAN is observed through the UML design. The node is considered as a stereotype and one process is transmitted from one machine to the other machine and data transmission rate is recorded through experimental study. A real case study of Babasaheb Bhimrao Ambedkar Central University is considered and results are depicted in the form of graphs and table.

  1. Dispersal governs the reorganization of ecological networks under environmental change.

    Science.gov (United States)

    Thompson, Patrick L; Gonzalez, Andrew

    2017-05-08

    Ecological networks, such as food webs, mutualist webs and host-parasite webs, are reorganizing as species abundances and spatial distributions shift in response to environmental change. Current theoretical expectations for how this reorganization will occur are available for competition or for parts of interaction networks, but these may not extend to more complex networks. Here we use metacommunity theory to develop new expectations for how complex networks will reorganize under environmental change, and show that dispersal is crucial for determining the degree to which networks will retain their composition and structure. When dispersal between habitat patches is low, all types of species interactions act as a strong determinant for whether species can colonize suitable habitats. This colonization resistance drives species turnover, which breaks apart current networks and leads to the formation of new networks. However, when dispersal rates are increased, colonists arrive in high abundance in habitats where they are well adapted, so interactions with resident species contribute less to colonization success. Dispersal ensures that species associations are maintained as they shift in space, so networks retain similar composition and structure. The crucial role of dispersal reinforces the need to manage habitat connectivity to sustain species and interaction diversity into the future.

  2. Ecological criterion effect on the forest road network longitudinal gradient

    Directory of Open Access Journals (Sweden)

    Petr Hrůza

    2013-01-01

    Full Text Available The specific way in which a forest road is designed affects the management in the forest environment and timber transport. The aim of this study was to find out whether an inclusion of the ecological criterion in the forest road design will change the parameter of the longitudinal gradient of forest hauling roads and whether these changes will have an effect on the accessibility of forest stands by timber hauling machinery. The possible changes in the longitudinal gradient can also affect the technology of forest road surfacing and the selection of the appropriate surface type. We can state that an inclusion of the ecological criterion in the forest road network design will bring statistically significant changes in longitudinal gradients of forest hauling roads. The mean longitudinal gradient of the current forest road network is 2.82 % and the mean longitudinal gradient of the forest road network designed with inclusion of the ecological criterion is 4.82 %. The results show statistically significant changes in the longitudinal parameters of forest hauling roads. However, it will not bring a need for a change in construction technology, and will not affect the accessibility of forest stands by timber hauling machinery.

  3. Sensory ecology and perceptual allocation: new prospects for neural networks.

    Science.gov (United States)

    Phelps, Steven M

    2007-03-29

    Sensory ecology provides a conceptual framework for considering how animals ought to design sensory systems to capture meaningful information from their environments. The framework has been particularly successful at describing how one should allocate sensory receptors to maximize performance on a given task. Neural networks, in contrast, have made unique contributions to understanding how 'hidden preferences' can emerge as a by-product of sensory design. The two frameworks comprise complementary techniques for understanding the design and the evolution of sensation. This article reviews empirical literature from multiple modalities and levels of sensory processing, considering vision, audition and touch from the viewpoints of sensory ecology and neuroethology. In the process, it presents modifications of extant neural network algorithms that would allow a more effective integration of these diverse approaches. Together, the reviewed literature suggests important advances that can be made by explicitly formulating neural network models in terms of sensory ecology, by incorporating neural costs into models of perceptual evolution and by exploring how such demands interact with historical forces.

  4. Mobile Node Localization in Cellular Networks

    Directory of Open Access Journals (Sweden)

    Yasir Malik

    2012-01-01

    Full Text Available Location information is the major component in location based applications. This information is used in different safety and service oriented applications to provide users with services according to their Geolocation. There are many approaches to locate mobile nodes in indoor and outdoor environments. In thispaper, we are interested in outdoor localization particularly in cellular networks of mobile nodes andpresented a localization method based on cell and user location information. Our localization method is based on hello message delay (sending and receiving time and coordinate information of Base Transceiver Station (BTSs. To validate our method across cellular network, we implemented and simulated our method in two scenarios i.e. maintaining database of base stations in centralize and distributed system. Simulation results show the effectiveness of our approach and its implementation applicability in telecommunication systems.

  5. Mobile node localization in cellular networks

    CERN Document Server

    Malik, Yasir; Abdulrazak, Bessam; Tariq, Usman; 10.5121/ijwmn.2011.3607

    2012-01-01

    Location information is the major component in location based applications. This information is used in different safety and service oriented applications to provide users with services according to their Geolocation. There are many approaches to locate mobile nodes in indoor and outdoor environments. In this paper, we are interested in outdoor localization particularly in cellular networks of mobile nodes and presented a localization method based on cell and user location information. Our localization method is based on hello message delay (sending and receiving time) and coordinate information of Base Transceiver Station (BTSs). To validate our method across cellular network, we implemented and simulated our method in two scenarios i.e. maintaining database of base stations in centralize and distributed system. Simulation results show the effectiveness of our approach and its implementation applicability in telecommunication systems.

  6. Ecological network analysis of an urban water metabolic system: model development, and a case study for Beijing.

    Science.gov (United States)

    Zhang, Yan; Yang, Zhifeng; Fath, Brian D

    2010-09-15

    Using ecological network analysis, we analyzed the network structure and ecological relationships in an urban water metabolic system. We developed an ecological network model for the system, and used Beijing as an example of analysis based on the model. We used network throughflow analysis to determine the flows among components, and measured both indirect and direct flows. Using a network utility matrix, we determined the relationships and degrees of mutualism among six compartments--1) local environment, 2) rainwater collection, 3) industry, 4) agriculture, 5) domestic sector, and 6) wastewater recycling--which represent producer, consumer, and reducer trophic levels. The capacity of producers to provide water for Beijing decreased from 2003 to 2007, and consumer demand for water decreased due to decreasing industrial and agricultural demand; the recycling capacity of reducers also improved, decreasing the discharge pressure on the environment. The ecological relationships associated with the local environment or the wastewater recycling sector changed little from 2003 to 2007. From 2003 to 2005, the main changes in the ecological relationships among components of Beijing's water metabolic system mostly occurred between the local environment, the industrial and agricultural sectors, and the domestic sector, but by 2006 and 2007, the major change was between the local environment, the agricultural sector, and the industrial sector. The other ecological relationships did not change during the study period. Although Beijing's mutualism indices remained generally stable, the ecological relationships among compartments changed greatly. Our analysis revealed ways to further optimize this system and the relationships among compartments, thereby optimizing future urban water resources development.

  7. Networking for Education for Sustainable Development in Austria: The Austrian ECOLOG-Schools Programme

    Science.gov (United States)

    Rauch, Franz

    2016-01-01

    This case describes networking for education for sustainable development within the Austrian ECOLOG-schools network. The article presents theoretical concepts of networks in education in general, and the organization of the ECOLOG-network in particular. Based upon these foundations, the concept and results of a participatory evaluation study are…

  8. Networking for Education for Sustainable Development in Austria: The Austrian ECOLOG-Schools Programme

    Science.gov (United States)

    Rauch, Franz

    2016-01-01

    This case describes networking for education for sustainable development within the Austrian ECOLOG-schools network. The article presents theoretical concepts of networks in education in general, and the organization of the ECOLOG-network in particular. Based upon these foundations, the concept and results of a participatory evaluation study are…

  9. Finding local communities in protein networks

    Directory of Open Access Journals (Sweden)

    Teng Shang-Hua

    2009-09-01

    Full Text Available Abstract Background Protein-protein interactions (PPIs play fundamental roles in nearly all biological processes, and provide major insights into the inner workings of cells. A vast amount of PPI data for various organisms is available from BioGRID and other sources. The identification of communities in PPI networks is of great interest because they often reveal previously unknown functional ties between proteins. A large number of global clustering algorithms have been applied to protein networks, where the entire network is partitioned into clusters. Here we take a different approach by looking for local communities in PPI networks. Results We develop a tool, named Local Protein Community Finder, which quickly finds a community close to a queried protein in any network available from BioGRID or specified by the user. Our tool uses two new local clustering algorithms Nibble and PageRank-Nibble, which look for a good cluster among the most popular destinations of a short random walk from the queried vertex. The quality of a cluster is determined by proportion of outgoing edges, known as conductance, which is a relative measure particularly useful in undersampled networks. We show that the two local clustering algorithms find communities that not only form excellent clusters, but are also likely to be biologically relevant functional components. We compare the performance of Nibble and PageRank-Nibble to other popular and effective graph partitioning algorithms, and show that they find better clusters in the graph. Moreover, Nibble and PageRank-Nibble find communities that are more functionally coherent. Conclusion The Local Protein Community Finder, accessible at http://xialab.bu.edu/resources/lpcf, allows the user to quickly find a high-quality community close to a queried protein in any network available from BioGRID or specified by the user. We show that the communities found by our tool form good clusters and are functionally coherent

  10. RELAY ALGORITHM BASED ON NETWORK CODING IN WIRELESS LOCAL NETWORK

    Institute of Scientific and Technical Information of China (English)

    Wang Qi; Wang Qingshan; Wang Dongxue

    2013-01-01

    The network coding is a new technology in the field of information in 21st century.It could enhance the network throughput and save the energy consumption,and is mainly based on the single transmission rate.However,with the development of wireless network and equipment,wireless local network MAC protocols have already supported the multi-rate transmission.This paper investigates the optimal relay selection problem based on network coding.Firstly,the problem is formulated as an optimization problem.Moreover,a relay algorithm based on network coding is proposed and the transmission time gain of our algorithm over the traditional relay algorithm is analyzed.Lastly,we compare total transmission time and the energy consumption of our proposed algorithm,Network Coding with Relay Assistance (NCRA),Transmission Request (TR),and the Direct Transmission (DT) without relay algorithm by adopting IEEE 802.11b.The simulation results demonstrate that our algorithm that improves the coding opportunity by the cooperation of the relay nodes leads to the transmission time decrease of up to 17% over the traditional relay algorithms.

  11. Cross-Industry Spatially Localized Innovation Networks

    Directory of Open Access Journals (Sweden)

    Aleksandr Evseevich Karlik

    2016-12-01

    Full Text Available This article’s objective is to develop conceptual approach to the study of key decision-making factors of cross-industry spatially localized innovation networks regularities by the application of quantitative and qualitative data of St. Petersburg Innovation and Technology Cluster of Machinery Manufacturing and Metalworking. The paper is based on the previous research findings which conclude that such networks have a set of opportunities and constraints for innovation. The hypothesis is that in the clusters, representing a special type of these networks, the spatial proximity partly offsets the negative impact of industrial distance. The authors propose a structural and logical model of strategic decision-making to analyze these effects on innovation. They specify network’s influences on performance: cognitive diversity; knowledge and expertise; structural autonomy and equivalence. The model is applied to spatially localized cross-industry cluster and then improved in accordance with the obtained results for accounting resource flows. It allowed to take into account the dynamics of innovation activity and to develop the practical implications in the particular business context. The analysis identified the peculiarities of spatially localized crossindustry innovation cooperation in perspective of the combinations of tangible resources, information and other intangible resources for the renewal of mature industries. The research results can be used in business as well as in industrial and regional economic policy. In the conclusion, the article outlines future research directions: a comprehensive empirical study with the analysis of data on the factors of cross-industry cooperation which were identified in this paper with testing of causal relations; the developing an approach to the study of spatially localized networks based on the exchange of primary resources in the economic system stability framework.

  12. Spreading to localized targets in complex networks

    Science.gov (United States)

    Sun, Ye; Ma, Long; Zeng, An; Wang, Wen-Xu

    2016-12-01

    As an important type of dynamics on complex networks, spreading is widely used to model many real processes such as the epidemic contagion and information propagation. One of the most significant research questions in spreading is to rank the spreading ability of nodes in the network. To this end, substantial effort has been made and a variety of effective methods have been proposed. These methods usually define the spreading ability of a node as the number of finally infected nodes given that the spreading is initialized from the node. However, in many real cases such as advertising and news propagation, the spreading only aims to cover a specific group of nodes. Therefore, it is necessary to study the spreading ability of nodes towards localized targets in complex networks. In this paper, we propose a reversed local path algorithm for this problem. Simulation results show that our method outperforms the existing methods in identifying the influential nodes with respect to these localized targets. Moreover, the influential spreaders identified by our method can effectively avoid infecting the non-target nodes in the spreading process.

  13. Localization of troubles in telephone cable networks

    Energy Technology Data Exchange (ETDEWEB)

    Chuxin Chen; Hollidge, T.L.; Sharma, D.D. [Pacific Bell, San Ramon, CA (United States)

    1996-12-31

    This paper describes an intelligent system which detects the location of troubles in a local telephone cable network. Such a task is very challenging, tedious, and requires human experts with years of experience and high analytical skills. Our system captures the expertise and knowledge required for this task, along with automated access to database systems, so that the system can help a human analyst to pin-point network trouble location more efficiently and accurately, ultimately reducing the cost of maintenance and repair. The system utilizes probabilistic reasoning techniques and logical operators to determine which plant component has the highest failure probability. This is achieved by building a topology of the local cable network, constructing a causal net which contains belief of failure for each plant component, given their current status, history data, cable pair distribution, and connectivity to other components. The Trouble Localization (TL) Module described in this paper is a crucial part of a larger system: Outside Plant Analysis System (OPAS) which has been deployed Statewide for over nine months at Pacific Bell PMAC centers. The TL system module utilizes AI and Object-Oriented technology. It is implemented in C++ on Unix workstations, and its graphical user interface is in an X Window environment.

  14. Dynamic Localization Schemes in Malicious Sensor Networks

    Directory of Open Access Journals (Sweden)

    Kaiqi Xiong

    2009-10-01

    Full Text Available Wireless sensor networks (WSN have recently shown many potential military and civilian applications, especially those used in hostile environments where malicious adversaries can be present. The accuracy of location information is critical for such applications. It is impractical to have a GPS device on each sensor in WSN due to costs. Most of the existing location discovery schemes can only be used in the trusted environment. Recent research has addressed security issues in sensor network localization, but to the best of our knowledge, none have completely solved the secure localization problem. In this paper, we propose novel schemes for secure dynamic localization in sensor networks. These proposed schemes can tolerate up to 50% of beacon nodes being malicious, and they have linear computation time with respect to the number of reference nodes. Our security analysis has showed that our schemes are applicable and resilient to attacks from adversaries. We have further conducted simulations to analyze and compare the performance of these schemes, and to indicate when each should be used. The efficiencies of each method shows why we needed to propose multiple methods.

  15. Physiological regulatory networks: ecological roles and evolutionary constraints.

    Science.gov (United States)

    Cohen, Alan A; Martin, Lynn B; Wingfield, John C; McWilliams, Scott R; Dunne, Jennifer A

    2012-08-01

    Ecological and evolutionary physiology has traditionally focused on one aspect of physiology at a time. Here, we discuss the implications of considering physiological regulatory networks (PRNs) as integrated wholes, a perspective that reveals novel roles for physiology in organismal ecology and evolution. For example, evolutionary response to changes in resource abundance might be constrained by the role of dietary micronutrients in immune response regulation, given a particular pathogen environment. Because many physiological components impact more than one process, organismal homeostasis is maintained, individual fitness is determined and evolutionary change is constrained (or facilitated) by interactions within PRNs. We discuss how PRN structure and its system-level properties could determine both individual performance and patterns of physiological evolution.

  16. Underwater Electromagnetic Sensor Networks, Part II: Localization and Network Simulations

    Directory of Open Access Journals (Sweden)

    Javier Zazo

    2016-12-01

    Full Text Available In the first part of the paper, we modeled and characterized the underwater radio channel in shallowwaters. In the second part,we analyze the application requirements for an underwaterwireless sensor network (U-WSN operating in the same environment and perform detailed simulations. We consider two localization applications, namely self-localization and navigation aid, and propose algorithms that work well under the specific constraints associated with U-WSN, namely low connectivity, low data rates and high packet loss probability. We propose an algorithm where the sensor nodes collaboratively estimate their unknown positions in the network using a low number of anchor nodes and distance measurements from the underwater channel. Once the network has been self-located, we consider a node estimating its position for underwater navigation communicating with neighboring nodes. We also propose a communication system and simulate the whole electromagnetic U-WSN in the Castalia simulator to evaluate the network performance, including propagation impairments (e.g., noise, interference, radio parameters (e.g., modulation scheme, bandwidth, transmit power, hardware limitations (e.g., clock drift, transmission buffer and complete MAC and routing protocols. We also explain the changes that have to be done to Castalia in order to perform the simulations. In addition, we propose a parametric model of the communication channel that matches well with the results from the first part of this paper. Finally, we provide simulation results for some illustrative scenarios.

  17. Underwater Electromagnetic Sensor Networks, Part II: Localization and Network Simulations.

    Science.gov (United States)

    Zazo, Javier; Macua, Sergio Valcarcel; Zazo, Santiago; Pérez, Marina; Pérez-Álvarez, Iván; Jiménez, Eugenio; Cardona, Laura; Brito, Joaquín Hernández; Quevedo, Eduardo

    2016-12-17

    In the first part of the paper, we modeled and characterized the underwater radio channel in shallowwaters. In the second part,we analyze the application requirements for an underwaterwireless sensor network (U-WSN) operating in the same environment and perform detailed simulations. We consider two localization applications, namely self-localization and navigation aid, and propose algorithms that work well under the specific constraints associated with U-WSN, namely low connectivity, low data rates and high packet loss probability. We propose an algorithm where the sensor nodes collaboratively estimate their unknown positions in the network using a low number of anchor nodes and distance measurements from the underwater channel. Once the network has been self-located, we consider a node estimating its position for underwater navigation communicating with neighboring nodes. We also propose a communication system and simulate the whole electromagnetic U-WSN in the Castalia simulator to evaluate the network performance, including propagation impairments (e.g., noise, interference), radio parameters (e.g., modulation scheme, bandwidth, transmit power), hardware limitations (e.g., clock drift, transmission buffer) and complete MAC and routing protocols. We also explain the changes that have to be done to Castalia in order to perform the simulations. In addition, we propose a parametric model of the communication channel that matches well with the results from the first part of this paper. Finally, we provide simulation results for some illustrative scenarios.

  18. Underwater Electromagnetic Sensor Networks, Part II: Localization and Network Simulations

    Science.gov (United States)

    Zazo, Javier; Valcarcel Macua, Sergio; Zazo, Santiago; Pérez, Marina; Pérez-Álvarez, Iván; Jiménez, Eugenio; Cardona, Laura; Brito, Joaquín Hernández; Quevedo, Eduardo

    2016-01-01

    In the first part of the paper, we modeled and characterized the underwater radio channel in shallow waters. In the second part, we analyze the application requirements for an underwater wireless sensor network (U-WSN) operating in the same environment and perform detailed simulations. We consider two localization applications, namely self-localization and navigation aid, and propose algorithms that work well under the specific constraints associated with U-WSN, namely low connectivity, low data rates and high packet loss probability. We propose an algorithm where the sensor nodes collaboratively estimate their unknown positions in the network using a low number of anchor nodes and distance measurements from the underwater channel. Once the network has been self-located, we consider a node estimating its position for underwater navigation communicating with neighboring nodes. We also propose a communication system and simulate the whole electromagnetic U-WSN in the Castalia simulator to evaluate the network performance, including propagation impairments (e.g., noise, interference), radio parameters (e.g., modulation scheme, bandwidth, transmit power), hardware limitations (e.g., clock drift, transmission buffer) and complete MAC and routing protocols. We also explain the changes that have to be done to Castalia in order to perform the simulations. In addition, we propose a parametric model of the communication channel that matches well with the results from the first part of this paper. Finally, we provide simulation results for some illustrative scenarios. PMID:27999309

  19. Digital Ecology: Coexistence and Domination among Interacting Networks

    Science.gov (United States)

    Kleineberg, Kaj-Kolja; Boguñá, Marián

    2015-05-01

    The overwhelming success of Web 2.0, within which online social networks are key actors, has induced a paradigm shift in the nature of human interactions. The user-driven character of Web 2.0 services has allowed researchers to quantify large-scale social patterns for the first time. However, the mechanisms that determine the fate of networks at the system level are still poorly understood. For instance, the simultaneous existence of multiple digital services naturally raises questions concerning which conditions these services can coexist under. Analogously to the case of population dynamics, the digital world forms a complex ecosystem of interacting networks. The fitness of each network depends on its capacity to attract and maintain users’ attention, which constitutes a limited resource. In this paper, we introduce an ecological theory of the digital world which exhibits stable coexistence of several networks as well as the dominance of an individual one, in contrast to the competitive exclusion principle. Interestingly, our theory also predicts that the most probable outcome is the coexistence of a moderate number of services, in agreement with empirical observations.

  20. Design of an ecological network for Piano di Navelli (Abruzzo); networks for LIFEE

    NARCIS (Netherlands)

    Grift, van der E.A.; Sluis, van der T.

    2003-01-01

    This report provides a design for an ecological network at Piano di Navelli, Abruzzo, Italy. The design is based on habitat and corridor requirements of five indicator species: green lizard (Lacerta bilineata), Italian crested newt (Triturus carnifex)water shrew (Neomys fodiens), hedgehog (Erinaceus

  1. LANES - LOCAL AREA NETWORK EXTENSIBLE SIMULATOR

    Science.gov (United States)

    Gibson, J.

    1994-01-01

    The Local Area Network Extensible Simulator (LANES) provides a method for simulating the performance of high speed local area network (LAN) technology. LANES was developed as a design and analysis tool for networking on board the Space Station. The load, network, link and physical layers of a layered network architecture are all modeled. LANES models to different lower-layer protocols, the Fiber Distributed Data Interface (FDDI) and the Star*Bus. The load and network layers are included in the model as a means of introducing upper-layer processing delays associated with message transmission; they do not model any particular protocols. FDDI is an American National Standard and an International Organization for Standardization (ISO) draft standard for a 100 megabit-per-second fiber-optic token ring. Specifications for the LANES model of FDDI are taken from the Draft Proposed American National Standard FDDI Token Ring Media Access Control (MAC), document number X3T9.5/83-16 Rev. 10, February 28, 1986. This is a mature document describing the FDDI media-access-control protocol. Star*Bus, also known as the Fiber Optic Demonstration System, is a protocol for a 100 megabit-per-second fiber-optic star-topology LAN. This protocol, along with a hardware prototype, was developed by Sperry Corporation under contract to NASA Goddard Space Flight Center as a candidate LAN protocol for the Space Station. LANES can be used to analyze performance of a networking system based on either FDDI or Star*Bus under a variety of loading conditions. Delays due to upper-layer processing can easily be nullified, allowing analysis of FDDI or Star*Bus as stand-alone protocols. LANES is a parameter-driven simulation; it provides considerable flexibility in specifying both protocol an run-time parameters. Code has been optimized for fast execution and detailed tracing facilities have been included. LANES was written in FORTRAN 77 for implementation on a DEC VAX under VMS 4.6. It consists of two

  2. Towards structural controllability of local-world networks

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Shiwen, E-mail: sunsw80@126.com [Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology, Tianjin University of Technology, Tianjin 300384 (China); Key Laboratory of Computer Vision and System (Tianjin University of Technology), Ministry of Education, Tianjin 300384 (China); Ma, Yilin; Wu, Yafang; Wang, Li; Xia, Chengyi [Tianjin Key Laboratory of Intelligence Computing and Novel Software Technology, Tianjin University of Technology, Tianjin 300384 (China); Key Laboratory of Computer Vision and System (Tianjin University of Technology), Ministry of Education, Tianjin 300384 (China)

    2016-05-20

    Controlling complex networks is of vital importance in science and engineering. Meanwhile, local-world effect is an important ingredient which should be taken into consideration in the complete description of real-world complex systems. In this letter, structural controllability of a class of local-world networks is investigated. Through extensive numerical simulations, firstly, effects of local world size M and network size N on structural controllability are examined. For local-world networks with sparse topological configuration, compared to network size, local-world size can induce stronger influence on controllability, however, for dense networks, controllability is greatly affected by network size and local-world effect can be neglected. Secondly, relationships between controllability and topological properties are analyzed. Lastly, the robustness of local-world networks under targeted attacks regarding structural controllability is discussed. These results can help to deepen the understanding of structural complexity and connectivity patterns of complex systems. - Highlights: • Structural controllability of a class of local-world networks is investigated. • For sparse local-world networks, compared to network size, local-world size can bring stronger influence on controllability. • For dense networks, controllability is greatly affected by network size and the effect of local-world size can be neglected. • Structural controllability against targeted node attacks is discussed.

  3. Anchored boundary conditions for locally isostatic networks

    Science.gov (United States)

    Theran, Louis; Nixon, Anthony; Ross, Elissa; Sadjadi, Mahdi; Servatius, Brigitte; Thorpe, M. F.

    2015-11-01

    Finite pieces of locally isostatic networks have a large number of floppy modes because of missing constraints at the surface. Here we show that by imposing suitable boundary conditions at the surface the network can be rendered effectively isostatic. We refer to these as anchored boundary conditions. An important example is formed by a two-dimensional network of corner sharing triangles, which is the focus of this paper. Another way of rendering such networks isostatic is by adding an external wire along which all unpinned vertices can slide (sliding boundary conditions). This approach also allows for the incorporation of boundaries associated with internal holes and complex sample geometries, which are illustrated with examples. The recent synthesis of bilayers of vitreous silica has provided impetus for this work. Experimental results from the imaging of finite pieces at the atomic level need such boundary conditions, if the observed structure is to be computer refined so that the interior atoms have the perception of being in an infinite isostatic environment.

  4. Local self-uniformity in photonic networks

    Science.gov (United States)

    Sellers, Steven R.; Man, Weining; Sahba, Shervin; Florescu, Marian

    2017-01-01

    The interaction of a material with light is intimately related to its wavelength-scale structure. Simple connections between structure and optical response empower us with essential intuition to engineer complex optical functionalities. Here we develop local self-uniformity (LSU) as a measure of a random network's internal structural similarity, ranking networks on a continuous scale from crystalline, through glassy intermediate states, to chaotic configurations. We demonstrate that complete photonic bandgap structures possess substantial LSU and validate LSU's importance in gap formation through design of amorphous gyroid structures. Amorphous gyroid samples are fabricated via three-dimensional ceramic printing and the bandgaps experimentally verified. We explore also the wing-scale structuring in the butterfly Pseudolycaena marsyas and show that it possesses substantial amorphous gyroid character, demonstrating the subtle order achieved by evolutionary optimization and the possibility of an amorphous gyroid's self-assembly. PMID:28211466

  5. Detecting spatial ontogenetic niche shifts in complex dendritic ecological networks

    Science.gov (United States)

    Fields, William R.; Grant, Evan; Lowe, Winsor H.

    2017-01-01

    Ontogenetic niche shifts (ONS) are important drivers of population and community dynamics, but they can be difficult to identify for species with prolonged larval or juvenile stages, or for species that inhabit continuous habitats. Most studies of ONS focus on single transitions among discrete habitat patches at local scales. However, for species with long larval or juvenile periods, affinity for particular locations within connected habitat networks may differ among cohorts. The resulting spatial patterns of distribution can result from a combination of landscape-scale habitat structure, position of a habitat patch within a network, and local habitat characteristics—all of which may interact and change as individuals grow. We estimated such spatial ONS for spring salamanders (Gyrinophilus porphyriticus), which have a larval period that can last 4 years or more. Using mixture models to identify larval cohorts from size frequency data, we fit occupancy models for each age class using two measures of the branching structure of stream networks and three measures of stream network position. Larval salamander cohorts showed different preferences for the position of a site within the stream network, and the strength of these responses depended on the basin-wide spatial structure of the stream network. The isolation of a site had a stronger effect on occupancy in watersheds with more isolated headwater streams, while the catchment area, which is associated with gradients in stream habitat, had a stronger effect on occupancy in watersheds with more paired headwater streams. Our results show that considering the spatial structure of habitat networks can provide new insights on ONS in long-lived species.

  6. Monitoring network-design influence on assessment of ecological condition in wadeable streams

    Science.gov (United States)

    We investigated outcomes of three monitoring networks for assessing ecological character and condition of wadeable streams in the Waikato region, New Zealand. Sites were selected 1) based on a professional judgment network, 2) within categories of stream and watershed characteris...

  7. Localization Algorithms of Underwater Wireless Sensor Networks: A Survey

    Science.gov (United States)

    Han, Guangjie; Jiang, Jinfang; Shu, Lei; Xu, Yongjun; Wang, Feng

    2012-01-01

    In Underwater Wireless Sensor Networks (UWSNs), localization is one of most important technologies since it plays a critical role in many applications. Motivated by widespread adoption of localization, in this paper, we present a comprehensive survey of localization algorithms. First, we classify localization algorithms into three categories based on sensor nodes’ mobility: stationary localization algorithms, mobile localization algorithms and hybrid localization algorithms. Moreover, we compare the localization algorithms in detail and analyze future research directions of localization algorithms in UWSNs. PMID:22438752

  8. Ecological, historical and evolutionary determinants of modularity in weighted seed-dispersal networks

    DEFF Research Database (Denmark)

    Schleuning, Matthias; Ingmann, Lili; Strauß, Rouven

    2014-01-01

    algorithm to detect modularity in weighted bipartite networks in a global analysis of avian seed-dispersal networks. We define roles of species, such as connector values, for weighted and binary networks and associate them with avian species traits and phylogeny. The weighted, but not binary, analysis...... demonstrates the dominating impact of ecological factors on the structure of seed-dispersal networks, but also underscores the relevance of evolutionary history in shaping species roles in ecological communities....

  9. Designing and Evaluating Bamboo Harvesting Methods for Local Needs: Integrating Local Ecological Knowledge and Science

    Science.gov (United States)

    Darabant, András; Rai, Prem Bahadur; Staudhammer, Christina Lynn; Dorji, Tshewang

    2016-08-01

    Dendrocalamus hamiltonii, a large, clump-forming bamboo, has great potential to contribute towards poverty alleviation efforts across its distributional range. Harvesting methods that maximize yield while they fulfill local objectives and ensure sustainability are a research priority. Documenting local ecological knowledge on the species and identifying local users' goals for its production, we defined three harvesting treatments (selective cut, horseshoe cut, clear cut) and experimentally compared them with a no-intervention control treatment in an action research framework. We implemented harvesting over three seasons and monitored annually and two years post-treatment. Even though the total number of culms positively influenced the number of shoots regenerated, a much stronger relationship was detected between the number of culms harvested and the number of shoots regenerated, indicating compensatory growth mechanisms to guide shoot regeneration. Shoot recruitment declined over time in all treatments as well as the control; however, there was no difference among harvest treatments. Culm recruitment declined with an increase in harvesting intensity. When univariately assessing the number of harvested culms and shoots, there were no differences among treatments. However, multivariate analyses simultaneously considering both variables showed that harvested output of shoots and culms was higher with clear cut and horseshoe cut as compared to selective cut. Given the ease of implementation and issues of work safety, users preferred the horseshoe cut, but the lack of sustainability of shoot production calls for investigating longer cutting cycles.

  10. Ecological networks and greenways in Europe: reasoning and concepts

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The paper gives an overview of approaches towards ecological networks throughout Europe.It does not intend to present a completepicture, but to highlight common developments within countries and regions and show common principles and differences between countries andregions that have to be taken into account when developing a joint European initiative.Countries or regions that have not been included can beactive in the same way, but information was not accessible to the authors for different reasons.This overview shows the comparable trends indecline of landscapes and the diversity in approaches to biodiversity conservation and nature conservation planning.Understanding thedifferences and common issues are of utmost importance to generalise common principles and to understand the way neighbours and otherEuropean partners approach problems.

  11. Localizing and placement of network node functions in a network

    NARCIS (Netherlands)

    Strijkers, R.J.; Meulenhoff, P.J.

    2014-01-01

    The invention enables placement and use of a network node function in a second network node instead of using the network node function in a first network node. The network node function is e.g. a server function or a router function. The second network node is typically located in or close to the cl

  12. Localizing and placement of network node functions in a network

    NARCIS (Netherlands)

    Strijkers, R.J.; Meulenhoff, P.J.

    2014-01-01

    The invention enables placement and use of a network node function in a second network node instead of using the network node function in a first network node. The network node function is e.g. a server function or a router function. The second network node is typically located in or close to the

  13. Management of local economic and ecological system of coal processing company

    Science.gov (United States)

    Kiseleva, T. V.; Mikhailov, V. G.; Karasev, V. A.

    2016-10-01

    The management issues of local ecological and economic system of coal processing company - coal processing plant - are considered in the article. The objectives of the research are the identification and the analysis of local ecological and economic system (coal processing company) performance and the proposals for improving the mechanism to support the management decision aimed at improving its environmental safety. The data on the structure of run-of-mine coal processing products are shown. The analysis of main ecological and economic indicators of coal processing enterprises, characterizing the state of its environmental safety, is done. The main result of the study is the development of proposals to improve the efficiency of local enterprise ecological and economic system management, including technical, technological and business measures. The results of the study can be recommended to industrial enterprises to improve their ecological and economic efficiency.

  14. The assessment of marine reserve networks: guidelines for ecological evaluation: Chapter 11

    Science.gov (United States)

    Grorud-Colvert, Kirsten; Claudet, Joachim; Carr, Mark; Caselle, Jennifer; Day, Jon; Friedlander, Alan M.; Lester, Sarah E.; Lison de Loma, Thierry; Tissot, Brian; Malone, Dan; Claudet, Joachim

    2011-01-01

    As marine ecosystems are plagued by an ever-increasing suite of threats including climate change, pollution, habitat degradation, and fisheries impacts (Roessig et al., 2004; Lotze et al., 2006; Jackson, 2008), there are now no ocean areas that are exempt from anthropogenic impacts (Halpern et al., 2008). In order to preserve marine biodiversity, ecosystem function, and the goods and services provided by resistant and/or resilient systems, marine reserves have been increasingly recommended as part of an ecosystem-based approach to management (Browman and Stergiou, 2004; Levin et al., 2009). Marine reserves are defined as “areas of the ocean completely protected from all extractive and destructive activities” (Lubchenco et al., 2003) and can be experimental controls for evaluating the impact of these activities on marine ecosystems. Growing scientific information has shown consistent increases in species density, biomass, size, and diversity in response to full protection inside reserves of varying sizes and ages located in diverse regions (Claudet et al., 2008; Lester et al., 2009; Molloy et al., 2009). However, most of these data are from individual marine reserves and therefore have inherently limited transferability to networks of marine reserves, which when properly designed can outperform single marine reserves for a variety of ecological, economic, and social management goals (Roberts et al., 2003; Almany et al., 2009; Gaines et al., 2010).The concept of marine reserve networks grew out of a desire to achieve both conservation and fishery management goals by minimizing the potential negative economic, social, and cultural impacts of a single large reserve while still producing similar or even greater ecological and economic returns (Murray et al., 1999; Gaines et al., 2010). In addition, reserves networks can provide insurance by protecting areas across a region and spreading the risk that these sites may be impacted by localized catastrophes such as

  15. The ecology of dust: local- to global-scale perspectives

    Energy Technology Data Exchange (ETDEWEB)

    Whicker, Jeffrey J [Los Alamos National Laboratory; Field, Jason P [UA; Belnap, Jayne [NON LANL; Breshears, David D [UA; Neff, Jason [CU; Okin, Gregory S [UCLA; Painter, Thomas H [UNIV OF ARIZONA; Ravi, Sujith [UNIV OF ARIZONA; Reheis, Marith C [UCLA; Reynolds, Richard L [NON LANL

    2009-01-01

    Emission and redistribution of dust due to wind erosion in drylands drives major biogeochemical dynamics and provides important aeolian environmental connectivity at scales from individual plants up to the global scale. Yet, perhaps because most relevant research on aeolian processes has been presented in a geosciences rather than ecological context, most ecological studies do not explicitly consider dust-driven processes. To bridge this disciplinary gap, we provide a general overview of the ecological importance of dust, examine complex interactions between wind erosion and ecosystem dynamics from the plant-interspace scale to regional and global scales, and highlight specific examples of how disturbance affects these interactions and their consequences. Changes in climate and intensification of land use will both likely lead to increased dust production. To address these challenges, environmental scientists, land managers and policy makers need to more explicitly consider dust in resource management decisions.

  16. Attractor dynamics in local neuronal networks

    Directory of Open Access Journals (Sweden)

    Jean-Philippe eThivierge

    2014-03-01

    Full Text Available Patterns of synaptic connectivity in various regions of the brain are characterized by the presence of synaptic motifs, defined as unidirectional and bidirectional synaptic contacts that follow a particular configuration and link together small groups of neurons. Recent computational work proposes that a relay network (two populations communicating via a third, relay population of neurons can generate precise patterns of neural synchronization. Here, we employ two distinct models of neuronal dynamics and show that simulated neural circuits designed in this way are caught in a global attractor of activity that prevents neurons from modulating their response on the basis of incoming stimuli. To circumvent the emergence of a fixed global attractor, we propose a mechanism of selective gain inhibition that promotes flexible responses to external stimuli. We suggest that local neuronal circuits may employ this mechanism to generate precise patterns of neural synchronization whose transient nature delimits the occurrence of a brief stimulus.

  17. EEG source localization: a neural network approach.

    Science.gov (United States)

    Sclabassi, R J; Sonmez, M; Sun, M

    2001-07-01

    Functional activity in the brain is associated with the generation of currents and resultant voltages which may be observed on the scalp as the electroencephelogram. The current sources may be modeled as dipoles. The properties of the current dipole sources may be studied by solving either the forward or inverse problems. The forward problem utilizes a volume conductor model for the head, in which the potentials on the conductor surface are computed based on an assumed current dipole at an arbitrary location, orientation, and strength. In the inverse problem, on the other hand, a current dipole, or a group of dipoles, is identified based on the observed EEG. Both the forward and inverse problems are typically solved by numerical procedures, such as a boundary element method and an optimization algorithm. These approaches are highly time-consuming and unsuitable for the rapid evaluation of brain function. In this paper we present a different approach to these problems based on machine learning. We solve both problems using artificial neural networks which are trained off-line using back-propagation techniques to learn the complex source-potential relationships of head volume conduction. Once trained, these networks are able to generalize their knowledge to localize functional activity within the brain in a computationally efficient manner.

  18. Chimera patterns induced by distance-dependent power-law coupling in ecological networks

    Science.gov (United States)

    Banerjee, Tanmoy; Dutta, Partha Sharathi; Zakharova, Anna; Schöll, Eckehard

    2016-09-01

    This paper reports the occurrence of several chimera patterns and the associated transitions among them in a network of coupled oscillators, which are connected by a long-range interaction that obeys a distance-dependent power law. This type of interaction is common in physics and biology and constitutes a general form of coupling scheme, where by tuning the power-law exponent of the long-range interaction the coupling topology can be varied from local via nonlocal to global coupling. To explore the effect of the power-law coupling on collective dynamics, we consider a network consisting of a realistic ecological model of oscillating populations, namely the Rosenzweig-MacArthur model, and show that the variation of the power-law exponent mediates transitions between spatial synchrony and various chimera patterns. We map the possible spatiotemporal states and their scenarios that arise due to the interplay between the coupling strength and the power-law exponent.

  19. Ecological network analysis on global virtual water trade.

    Science.gov (United States)

    Yang, Zhifeng; Mao, Xufeng; Zhao, Xu; Chen, Bin

    2012-02-07

    Global water interdependencies are likely to increase with growing virtual water trade. To address the issues of the indirect effects of water trade through the global economic circulation, we use ecological network analysis (ENA) to shed insight into the complicated system interactions. A global model of virtual water flow among agriculture and livestock production trade in 1995-1999 is also built as the basis for network analysis. Control analysis is used to identify the quantitative control or dependency relations. The utility analysis provides more indicators for describing the mutual relationship between two regions/countries by imitating the interactions in the ecosystem and distinguishes the beneficiary and the contributor of virtual water trade system. Results show control and utility relations can well depict the mutual relation in trade system, and direct observable relations differ from integral ones with indirect interactions considered. This paper offers a new way to depict the interrelations between trade components and can serve as a meaningful start as we continue to use ENA in providing more valuable implications for freshwater study on a global scale.

  20. Viewing the effects of species loss in complex ecological networks.

    Science.gov (United States)

    Zhao, Lei; Zhang, Huayong; Tian, Wang; Li, Ran; Xu, Xiang

    2017-03-01

    Species loss is becoming a major threat to ecosystems. An urgent task in ecology is to predict the consequence of species loss which requires an extending of our traditional study of the topology of network structure to the population dynamic analyses in complex food webs. Here, via numerical simulations of the model combining structural networks with nonlinear bioenergetic models of population dynamics, we analyzed the secondary effects of species removal on biomass distribution and population stability, as well as the factors influencing these effects. We found that the biomass of target species, the nutrient supply, and the trophic level of target species were the three most significant determiners for the effects of species loss. Species loss had large negative effect on the biomass of the species with small biomass or intermediate trophic levels, especially in infertile environment. The population stability of the species with large biomass or low trophic level is easily to be influenced especially in nutrient-rich environment. Our findings indicate the species which are easily to be affected by species loss in food webs, which may help ecologists to outline a better conservation policy. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. [Eutrophication control in local area by physic-ecological engineering].

    Science.gov (United States)

    Li, Qiu-Hua; Xia, Pin-Hua; Wu, Hong; Lin, Tao; Zhang, You-Chun; Li, Cun-Xiong; Chen, Li-Li; Yang, Fan

    2012-07-01

    An integrated physical and ecological engineering experiment for ecological remediation was performed at the Maixi River bay in Baihua Reservoir Guizhou Province, China. The results show that eutrophic parameters, such as total nitrogen, total phosphorus, chlorophyll a and chemical oxygen demand from the experimental site (enclosed water) were significantly lower than those of the reference site. The largest differences between the sites were 0.61 mg x L(-1), 0.041 mg x L(-1), 23.06 microg x L(-1), 8.4 mg x L(-1) respectively; experimental site transparency was > 1.50 m which was significantly higher than that of the reference site. The eutrophic index of the experimental site was oligo-trophic and mid-trophic, while the control site was mid-trophic state and eutrophic state. Phytoplankton abundance was 2 125.5 x 10(4) cells x L(-1) in June, 2011 at the control site,but phytoplankton abundance was lower at the experimental site with 33 x 10(4) cells x L(-1). Cyanobacteria dominated phytoplankton biomass at both sites, however the experimental site consisted of a higher proportion of diatoms and dinoflagellates. After more than one year of operation, the ecological engineering technology effectively controlled the occurrence of algae blooms, changed phytoplankton community structure, and controlled the negative impacts of eutrophication. Integrating physical and ecological engineering technology could improve water quality for reservoirs on the Guizhou plateau.

  2. Multiplex social ecological network analysis reveals how social changes affect community robustness more than resource depletion.

    Science.gov (United States)

    Baggio, Jacopo A; BurnSilver, Shauna B; Arenas, Alex; Magdanz, James S; Kofinas, Gary P; De Domenico, Manlio

    2016-11-29

    Network analysis provides a powerful tool to analyze complex influences of social and ecological structures on community and household dynamics. Most network studies of social-ecological systems use simple, undirected, unweighted networks. We analyze multiplex, directed, and weighted networks of subsistence food flows collected in three small indigenous communities in Arctic Alaska potentially facing substantial economic and ecological changes. Our analysis of plausible future scenarios suggests that changes to social relations and key households have greater effects on community robustness than changes to specific wild food resources.

  3. Connecting Social Networks with Ecosystem Services for Watershed Governance: a Social-Ecological Network Perspective Highlights the Critical Role of Bridging Organizations

    Directory of Open Access Journals (Sweden)

    Kaitlyn J. Rathwell

    2012-06-01

    Full Text Available In many densely settled agricultural watersheds, water quality is a point of conflict between amenity and agricultural activities because of the varied demands and impacts on shared water resources. Successful governance of these watersheds requires coordination among different activities. Recent research has highlighted the role that social networks between management entities can play to facilitate cross-scale interaction in watershed governance. For example, bridging organizations can be positioned in social networks to bridge local initiatives done by single municipalities across whole watersheds. To better understand the role of social networks in social-ecological system dynamics, we combine a social network analysis of the water quality management networks held by local governments with a social-ecological analysis of variation in water management and ecosystem services across the Montérégie, an agricultural landscape near Montréal, Québec, Canada. We analyze municipal water management networks by using one-mode networks to represent direct collaboration between municipalities, and two-mode networks to capture how bridging organizations indirectly connect municipalities. We find that municipalities do not collaborate directly with one another but instead are connected via bridging organizations that span the water quality management network. We also discovered that more connected municipalities engaged in more water management activities. However, bridging organizations preferentially connected with municipalities that used more tourism related ecosystem services rather than those that used more agricultural ecosystem services. Many agricultural municipalities were relatively isolated, despite being the main producers of water quality problems. In combination, these findings suggest that further strengthening the water management network in the Montérégie will contribute to improving water quality in the region. However, such

  4. The Role of Marketing in Local Food Networks

    Directory of Open Access Journals (Sweden)

    Margrete Haugum

    2017-01-01

    Full Text Available Local food producers are often advised to collaborate with other local food producers to jointly participate in marketing and sales activities. Local food producers are often small and must operate many different activities to run their company, so the idea to collaborate may help them to become more efficient. We explore the role of marketing in local food networks through an analysis of marketing strategies and marketing mix in six local food networks in central Norway. When producers participate in food networks, they disconnect from direct relationships with their consumers. The value of this relationship must be considered in addition to costs related to sales and distribution in the network. The networks rely on regional products and regional branding as the main marketing strategy and promote local and localized products.

  5. A new local-world evolving network model

    Institute of Scientific and Technical Information of China (English)

    Qin Sen; Dai Guan-Zhong

    2009-01-01

    In some real complex networks, only a few nodes can obtain the global information about the entire networks, but most of the nodes own only local connections therefore own only local information of the networks. A new local-world evolving network model is proposed in this paper. In the model, not all the nodes obtain local network information, which is different from the local world network model proposed by Li and Chen (LC model). In the LC model, each node has only the local connections therefore owns only local information about the entire networks. Theoretical analysis and numerical simulation show that adjusting the ratio of the number of nodes obtaining the global information of the network to the total number of nodes can effectively control the valuing range for the power-law exponent of the new network. Therefore, if the topological structure of a complex network, especially its exponent of power-law degree distribution, needs controlling, we just add or take away a few nodes which own the global information of the network.

  6. A data management proposal to connect in a hierarchical way nodes of the Spanish Long Term Ecological Research (LTER) network

    Science.gov (United States)

    Fuentes, Daniel; Pérez-Luque, Antonio J.; Bonet García, Francisco J.; Moreno-LLorca, Ricardo A.; Sánchez-Cano, Francisco M.; Suárez-Muñoz, María

    2017-04-01

    The Long Term Ecological Research (LTER) network aims to provide the scientific community, policy makers, and society with the knowledge and predictive understanding necessary to conserve, protect, and manage the ecosystems. LTER is organized into networks ranging from the global to national scale. In the top of network, the International Long Term Ecological Research (ILTER) Network coordinates among ecological researchers and LTER research networks at local, regional and global scales. In Spain, the Spanish Long Term Ecological Research (LTER-Spain) network was built to foster the collaboration and coordination between longest-lived ecological researchers and networks on a local scale. Currently composed by nine nodes, this network facilitates the data exchange, documentation and preservation encouraging the development of cross-disciplinary works. However, most nodes have no specific information systems, tools or qualified personnel to manage their data for continued conservation and there are no harmonized methodologies for long-term monitoring protocols. Hence, the main challenge is to place the nodes in its correct position in the network, providing the best tools that allow them to manage their data autonomously and make it easier for them to access information and knowledge in the network. This work proposes a connected structure composed by four LTER nodes located in southern Spain. The structure is built considering hierarchical approach: nodes that create information which is documented using metadata standards (such as Ecological Metadata Language, EML); and others nodes that gather metadata and information. We also take into account the capacity of each node to manage their own data and the premise that the data and metadata must be maintained where it is generated. The current state of the nodes is a follows: two of them have their own information management system (Sierra Nevada-Granada and Doñana Long-Term Socio-ecological Research Platform) and

  7. Epidemic spreading behavior in local-world evolving networks

    Institute of Scientific and Technical Information of China (English)

    Chengyi Xia; Zhongxin Liu; Zengqiang Chen; Shiwen Sun; Zhuzhi Yuan

    2008-01-01

    The susceptible-infected-susceptible (SIS) epidemic model is presented which can be used to study the epidemic spreading behavior in the local-world evolving network model. Local-world evolving model displays a transition from the exponential network to the scale-free network with respect to the connectivity distribution. From theoretical analyses and numerical simulations, we find that the epidemic spreading behavior on local-world networks also takes on some kind of transitional behaviors. The transitional behavior is further verified by comparing the spreading behavior of local-world network with that of random and scale-free networks. Some feasible control strategies are also proposed to keep from the epidemic spreading on networks.

  8. Local modularity for community detection in complex networks

    Science.gov (United States)

    Xiang, Ju; Hu, Tao; Zhang, Yan; Hu, Ke; Li, Jian-Ming; Xu, Xiao-Ke; Liu, Cui-Cui; Chen, Shi

    2016-02-01

    Community detection is a topic of interest in the study of complex networks such as the protein-protein interaction networks and metabolic networks. In recent years, various methods were proposed to detect community structures of the networks. Here, a kind of local modularity with tunable parameter is derived from the Newman-Girvan modularity by a special self-loop strategy that depends on the community division of the networks. By the self-loop strategy, one can easily control the definition of modularity, and the resulting modularity can be optimized by using the existing modularity optimization algorithms. The local modularity is used as the target function for community detection, and a self-consistent method is proposed for the optimization of the local modularity. We analyze the behaviors of the local modularity and show the validity of the local modularity in detecting community structures on various networks.

  9. A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network

    Science.gov (United States)

    Gardner, Toby A.; Ferreira, Joice; Barlow, Jos; Lees, Alexander C.; Parry, Luke; Vieira, Ima Célia Guimarães; Berenguer, Erika; Abramovay, Ricardo; Aleixo, Alexandre; Andretti, Christian; Aragão, Luiz E. O. C.; Araújo, Ivanei; de Ávila, Williams Souza; Bardgett, Richard D.; Batistella, Mateus; Begotti, Rodrigo Anzolin; Beldini, Troy; de Blas, Driss Ezzine; Braga, Rodrigo Fagundes; Braga, Danielle de Lima; de Brito, Janaína Gomes; de Camargo, Plínio Barbosa; Campos dos Santos, Fabiane; de Oliveira, Vívian Campos; Cordeiro, Amanda Cardoso Nunes; Cardoso, Thiago Moreira; de Carvalho, Déborah Reis; Castelani, Sergio André; Chaul, Júlio Cézar Mário; Cerri, Carlos Eduardo; Costa, Francisco de Assis; da Costa, Carla Daniele Furtado; Coudel, Emilie; Coutinho, Alexandre Camargo; Cunha, Dênis; D'Antona, Álvaro; Dezincourt, Joelma; Dias-Silva, Karina; Durigan, Mariana; Esquerdo, Júlio César Dalla Mora; Feres, José; Ferraz, Silvio Frosini de Barros; Ferreira, Amanda Estefânia de Melo; Fiorini, Ana Carolina; da Silva, Lenise Vargas Flores; Frazão, Fábio Soares; Garrett, Rachel; Gomes, Alessandra dos Santos; Gonçalves, Karoline da Silva; Guerrero, José Benito; Hamada, Neusa; Hughes, Robert M.; Igliori, Danilo Carmago; Jesus, Ederson da Conceição; Juen, Leandro; Junior, Miércio; Junior, José Max Barbosa de Oliveira; Junior, Raimundo Cosme de Oliveira; Junior, Carlos Souza; Kaufmann, Phil; Korasaki, Vanesca; Leal, Cecília Gontijo; Leitão, Rafael; Lima, Natália; Almeida, Maria de Fátima Lopes; Lourival, Reinaldo; Louzada, Júlio; Nally, Ralph Mac; Marchand, Sébastien; Maués, Márcia Motta; Moreira, Fátima M. S.; Morsello, Carla; Moura, Nárgila; Nessimian, Jorge; Nunes, Sâmia; Oliveira, Victor Hugo Fonseca; Pardini, Renata; Pereira, Heloisa Correia; Pompeu, Paulo Santos; Ribas, Carla Rodrigues; Rossetti, Felipe; Schmidt, Fernando Augusto; da Silva, Rodrigo; da Silva, Regina Célia Viana Martins; da Silva, Thiago Fonseca Morello Ramalho; Silveira, Juliana; Siqueira, João Victor; de Carvalho, Teotônio Soares; Solar, Ricardo R. C.; Tancredi, Nicola Savério Holanda; Thomson, James R.; Torres, Patrícia Carignano; Vaz-de-Mello, Fernando Zagury; Veiga, Ruan Carlo Stulpen; Venturieri, Adriano; Viana, Cecília; Weinhold, Diana; Zanetti, Ronald; Zuanon, Jansen

    2013-01-01

    Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far. PMID:23610172

  10. A social and ecological assessment of tropical land uses at multiple scales: the Sustainable Amazon Network.

    Science.gov (United States)

    Gardner, Toby A; Ferreira, Joice; Barlow, Jos; Lees, Alexander C; Parry, Luke; Vieira, Ima Célia Guimarães; Berenguer, Erika; Abramovay, Ricardo; Aleixo, Alexandre; Andretti, Christian; Aragão, Luiz E O C; Araújo, Ivanei; de Ávila, Williams Souza; Bardgett, Richard D; Batistella, Mateus; Begotti, Rodrigo Anzolin; Beldini, Troy; de Blas, Driss Ezzine; Braga, Rodrigo Fagundes; Braga, Danielle de Lima; de Brito, Janaína Gomes; de Camargo, Plínio Barbosa; Campos dos Santos, Fabiane; de Oliveira, Vívian Campos; Cordeiro, Amanda Cardoso Nunes; Cardoso, Thiago Moreira; de Carvalho, Déborah Reis; Castelani, Sergio André; Chaul, Júlio Cézar Mário; Cerri, Carlos Eduardo; Costa, Francisco de Assis; da Costa, Carla Daniele Furtado; Coudel, Emilie; Coutinho, Alexandre Camargo; Cunha, Dênis; D'Antona, Álvaro; Dezincourt, Joelma; Dias-Silva, Karina; Durigan, Mariana; Esquerdo, Júlio César Dalla Mora; Feres, José; Ferraz, Silvio Frosini de Barros; Ferreira, Amanda Estefânia de Melo; Fiorini, Ana Carolina; da Silva, Lenise Vargas Flores; Frazão, Fábio Soares; Garrett, Rachel; Gomes, Alessandra dos Santos; Gonçalves, Karoline da Silva; Guerrero, José Benito; Hamada, Neusa; Hughes, Robert M; Igliori, Danilo Carmago; Jesus, Ederson da Conceição; Juen, Leandro; Junior, Miércio; de Oliveira Junior, José Max Barbosa; de Oliveira Junior, Raimundo Cosme; Souza Junior, Carlos; Kaufmann, Phil; Korasaki, Vanesca; Leal, Cecília Gontijo; Leitão, Rafael; Lima, Natália; Almeida, Maria de Fátima Lopes; Lourival, Reinaldo; Louzada, Júlio; Mac Nally, Ralph; Marchand, Sébastien; Maués, Márcia Motta; Moreira, Fátima M S; Morsello, Carla; Moura, Nárgila; Nessimian, Jorge; Nunes, Sâmia; Oliveira, Victor Hugo Fonseca; Pardini, Renata; Pereira, Heloisa Correia; Pompeu, Paulo Santos; Ribas, Carla Rodrigues; Rossetti, Felipe; Schmidt, Fernando Augusto; da Silva, Rodrigo; da Silva, Regina Célia Viana Martins; da Silva, Thiago Fonseca Morello Ramalho; Silveira, Juliana; Siqueira, João Victor; de Carvalho, Teotônio Soares; Solar, Ricardo R C; Tancredi, Nicola Savério Holanda; Thomson, James R; Torres, Patrícia Carignano; Vaz-de-Mello, Fernando Zagury; Veiga, Ruan Carlo Stulpen; Venturieri, Adriano; Viana, Cecília; Weinhold, Diana; Zanetti, Ronald; Zuanon, Jansen

    2013-06-05

    Science has a critical role to play in guiding more sustainable development trajectories. Here, we present the Sustainable Amazon Network (Rede Amazônia Sustentável, RAS): a multidisciplinary research initiative involving more than 30 partner organizations working to assess both social and ecological dimensions of land-use sustainability in eastern Brazilian Amazonia. The research approach adopted by RAS offers three advantages for addressing land-use sustainability problems: (i) the collection of synchronized and co-located ecological and socioeconomic data across broad gradients of past and present human use; (ii) a nested sampling design to aid comparison of ecological and socioeconomic conditions associated with different land uses across local, landscape and regional scales; and (iii) a strong engagement with a wide variety of actors and non-research institutions. Here, we elaborate on these key features, and identify the ways in which RAS can help in highlighting those problems in most urgent need of attention, and in guiding improvements in land-use sustainability in Amazonia and elsewhere in the tropics. We also discuss some of the practical lessons, limitations and realities faced during the development of the RAS initiative so far.

  11. Local Area Network DI Agnostic Package

    Science.gov (United States)

    Oestereicher, Charles

    1984-08-01

    This paper describes the design of a Local Area Network (LAN) diagnostic package This program will contain "confidence" type test routines, and commands designed to aid in detecting failures and improve the use of the LAN services during normal operations. The approach selected requires installing the same copy of the program in selected bus interface units(bius) and a subset in all the others bius. Those bius containing the full set of options are the controlling nodes; more than one controlling node can run concurrently its own diagnostic program. Messages generated when exercising the different resources and interfaces of the LAN will be stored and/or displayed on appropriate positions. As a minimum the LAN will have one controlling node which will be the location of the LAN's technical control. The diagnostics will provide data to aid in mana-ging the system, accepting or declining requests for connections, allocating additional ports, declaring sectors inoperable, off lining nodes, devices, functions, and reconfiguring the system as necessary. Host computers can optionally have the full blown diagnostic program, which allows them to be a controlling node, or a subset of the diagnostic program with enough capabilities to interface with its host front end biu (hfe). The diagnostics will have its own application protocol and will utilize the ser-vices of the Internet Protocol (IP) to transport messages to their destinations.

  12. Studying the Complex Communities of Ants and Their Symbionts Using Ecological Network Analysis.

    Science.gov (United States)

    Ivens, Aniek B F; von Beeren, Christoph; Blüthgen, Nico; Kronauer, Daniel J C

    2016-01-01

    Ant colonies provide well-protected and resource-rich environments for a plethora of symbionts. Historically, most studies of ants and their symbionts have had a narrow taxonomic scope, often focusing on a single ant or symbiont species. Here we discuss the prospects of studying these assemblies in a community ecology context using the framework of ecological network analysis. We introduce three basic network metrics that we consider particularly relevant for improving our knowledge of ant-symbiont communities: interaction specificity, network modularity, and phylogenetic signal. We then discuss army ant symbionts as examples of large and primarily parasitic communities, and symbiotic sternorrhynchans as examples of generally smaller and primarily mutualistic communities in the context of these network analyses. We argue that this approach will provide new and complementary insights into the evolutionary and ecological dynamics between ants and their many associates, and will facilitate comparisons across different ant-symbiont assemblages as well as across different types of ecological networks.

  13. Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction.

    Science.gov (United States)

    Pires, Mathias M; Galetti, Mauro; Donatti, Camila I; Pizo, Marco A; Dirzo, Rodolfo; Guimarães, Paulo R

    2014-08-01

    The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.

  14. EXTENDED MONTE CARLO LOCALIZATION ALGORITHM FOR MOBILE SENSOR NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    A real-world localization system for wireless sensor networks that adapts for mobility and irregular radio propagation model is considered.The traditional range-based techniques and recent range-free localization schemes are not welt competent for localization in mobile sensor networks,while the probabilistic approach of Bayesian filtering with particle-based density representations provides a comprehensive solution to such localization problem.Monte Carlo localization is a Bayesian filtering method that approximates the mobile node’S location by a set of weighted particles.In this paper,an enhanced Monte Carlo localization algorithm-Extended Monte Carlo Localization (Ext-MCL) is suitable for the practical wireless network environment where the radio propagation model is irregular.Simulation results show the proposal gets better localization accuracy and higher localizable node number than previously proposed Monte Carlo localization schemes not only for ideal radio model,but also for irregular one.

  15. Sampling microbial communities in the National Ecological Observatory Network

    Science.gov (United States)

    Adams, H. E.; Parnell, J.; Powell, H.

    2012-12-01

    The National Ecological Observatory Network (NEON) is a national-scale research platform to enable the community to assess impacts of climate change, land-use change, and invasive species on ecosystem structure and function at regional and continental scales. The NEON Observatory will collect data on aquatic organisms over 30 years in 36 sites across the United States, including Alaska and Puerto Rico as well as terrestrial organisms at 60 sites including Hawaii. Included in the biological measurements are microbial measurements in terrestrial and aquatic environments, including small, wadeable streams and shallow lakes. Microbial sampling in both aquatic and terrestrial habitats is being planned to coincide with biogeochemical sampling due to similarity of time scale and influence of external drivers. Aquatic sampling is geared toward species diversity and function. Terrestrial sampling aims to collect data on diversity, function, and spatial distribution dynamics. We are in the process of prioritizing data products, so that the most dynamic processes such as enzymatic activity will be measured more frequently and more intensive measures such as metagenome sequence data will be measured on a periodic basis. Here we present our initial microbial sampling strategy and invite the community to provide comment on the design and learn about microbial data products from the Observatory.

  16. Our Social Roots: How Local Ecology Shapes Our Social Structures

    Science.gov (United States)

    Mace, Ruth

    There is overwhelming evidence that wide-ranging aspects of human biology and human behavior can be considered as adaptations to different subsistence systems. Wider environmental and ecological correlates of behavioral and cultural traits are generally best understood as being mediated by differences in subsistence strategies. Modes of subsistence profoundly influence both human biology, as documented in genetic changes, and human social behavior and cultural norms, such as kinship, marriage, descent, wealth inheritance, and political systems. Thus both cultural and biological factors usually need to be considered together in studies of human evolutionary ecology, combined in specifically defined evolutionary models. Models of cultural adaptation to environmental conditions can be subjected to the same or similar tests that behavioral ecologists have used to seek evidence for adaptive behavior in other species. Phylogenetic comparative methods are proving useful, both for studying co-evolutionary hypotheses (cultural and/or gene-culture co-evolution), and for estimating ancestral states of prehistoric societies. This form of formal cross-cultural comparison is helping to put history back into anthropology, and helping us to understand cultural evolutionary processes at a number of levels.

  17. Competition between global and local online social networks.

    Science.gov (United States)

    Kleineberg, Kaj-Kolja; Boguñá, Marián

    2016-04-27

    The overwhelming success of online social networks, the key actors in the Web 2.0 cosmos, has reshaped human interactions globally. To help understand the fundamental mechanisms which determine the fate of online social networks at the system level, we describe the digital world as a complex ecosystem of interacting networks. In this paper, we study the impact of heterogeneity in network fitnesses on the competition between an international network, such as Facebook, and local services. The higher fitness of international networks is induced by their ability to attract users from all over the world, which can then establish social interactions without the limitations of local networks. In other words, inter-country social ties lead to increased fitness of the international network. To study the competition between an international network and local ones, we construct a 1:1000 scale model of the digital world, consisting of the 80 countries with the most Internet users. Under certain conditions, this leads to the extinction of local networks; whereas under different conditions, local networks can persist and even dominate completely. In particular, our model suggests that, with the parameters that best reproduce the empirical overtake of Facebook, this overtake could have not taken place with a significant probability.

  18. Competition between global and local online social networks

    Science.gov (United States)

    Kleineberg, Kaj-Kolja; Boguñá, Marián

    2016-04-01

    The overwhelming success of online social networks, the key actors in the Web 2.0 cosmos, has reshaped human interactions globally. To help understand the fundamental mechanisms which determine the fate of online social networks at the system level, we describe the digital world as a complex ecosystem of interacting networks. In this paper, we study the impact of heterogeneity in network fitnesses on the competition between an international network, such as Facebook, and local services. The higher fitness of international networks is induced by their ability to attract users from all over the world, which can then establish social interactions without the limitations of local networks. In other words, inter-country social ties lead to increased fitness of the international network. To study the competition between an international network and local ones, we construct a 1:1000 scale model of the digital world, consisting of the 80 countries with the most Internet users. Under certain conditions, this leads to the extinction of local networks; whereas under different conditions, local networks can persist and even dominate completely. In particular, our model suggests that, with the parameters that best reproduce the empirical overtake of Facebook, this overtake could have not taken place with a significant probability.

  19. Local Area Networks and the Learning Lab of the Future.

    Science.gov (United States)

    Ebersole, Dennis C.

    1987-01-01

    Considers educational applications of local area computer networks and discusses industry standards for design established by the International Standards Organization (ISO) and Institute of Electrical and Electronic Engineers (IEEE). A futuristic view of a learning laboratory using a local area network is presented. (Author/LRW)

  20. An Application to WIN/ISIS Database on Local Network

    Directory of Open Access Journals (Sweden)

    Robert Lechien

    2005-07-01

    Full Text Available A Translated Article containing an application to how WIN/ISIS database work on local network. It starts with main definitions, and how to install WIN/ISIS on PC, and how to install it on the local network server.

  1. Synchronization in a Novel Local-World Dynamical Network Model

    Directory of Open Access Journals (Sweden)

    Jianeng Tang

    2014-01-01

    Full Text Available Advances in complex network research have recently stimulated increasing interests in understanding the relationship between the topology and dynamics of complex networks. In the paper, we study the synchronizability of a class of local-world dynamical networks. Then, we have proposed a local-world synchronization-optimal growth topology model. Compared with the local-world evolving network model, it exhibits a stronger synchronizability. We also investigate the robustness of the synchronizability with respect to random failures and the fragility of the synchronizability with specific removal of nodes.

  2. Local Area Networks: Vehicles for Connecting and Sharing Information.

    Science.gov (United States)

    Lipman, Art

    1993-01-01

    Describes local area networks (LANs) and discusses advantages of their use in schools for students and teachers, including networking in labs, media centers, and classrooms. Roles of the network supervisor and/or technician are explained, including making decisions about the rights of users and instruction and assistance. (LRW)

  3. Fibre Optics In A Multi-Star Wideband Local Network

    Science.gov (United States)

    Fox, J. R.

    1983-08-01

    Early experience has been gained with the switched-star type of network in the Fibrevision cable TV trial at Milton Keynes, and British Telecom are progressing towards a full-scale multi-star wideband local network. This paper discusses both the present and future use of fibre optics in this type of network.

  4. Optimal operation of water distribution networks under local pipe failures

    Institute of Scientific and Technical Information of China (English)

    TIAN Yi-mei; G.Y.FU; CHI Hai-yan; LIU Ye

    2007-01-01

    The optimal operation of water distribution networks under local pipe failures, such as water main breaks, was proposed.Based on a hydraulic analysis and a simulation of water distribution networks, a macroscopic model for a network under a local pipe failure was established by the statistical regression. After the operation objectives under a local pipe failure were determined, the optimal operation model was developed and solved by the genetic algorithm. The program was developed and examined by a city distribution network. The optimal operation alternative shows that the electricity cost is saved approximately 11%, the income of the water corporation is increased approximately 5%, and the pressure in the water distribution network is distributed evenly to ensure the network safe operation. Therefore, the proposed method for optimal operation under local pipe failure is feasible and cost-effective.

  5. Planning of Green Space Ecological Network in Urban Areas: An Example of Nanchang, China.

    Science.gov (United States)

    Li, Haifeng; Chen, Wenbo; He, Wei

    2015-10-15

    Green space plays an important role in sustainable urban development and ecology by virtue of multiple environmental, recreational, and economic benefits. Constructing an effective and harmonious urban ecological network and maintaining a sustainable living environment in response to rapid urbanization are the key issues required to be resolved by landscape planners. In this paper, Nanchang City, China was selected as a study area. Based on a series of landscape metrics, the landscape pattern analysis of the current (in 2005) and planned (in 2020) green space system were, respectively, conducted by using FRAGSTATS 3.3 software. Considering the actual situation of the Nanchang urban area, a "one river and two banks, north and south twin cities" ecological network was constructed by using network analysis. Moreover, the ecological network was assessed by using corridor structure analysis, and the improvement of an ecological network on the urban landscape was quantitatively assessed through a comparison between the ecological network and green space system planning. The results indicated that: (1) compared to the green space system in 2005, the planned green space system in 2020 of the Nanchang urban area will decline in both districts (Changnan and Changbei districts). Meanwhile, an increase in patch density and a decrease in mean patch size of green space patches at the landscape level implies the fragmentation of the urban green space landscape. In other words, the planned green space system does not necessarily improve the present green space system; (2) the ecological network of two districts has high corridor density, while Changnan's ecological network has higher connectivity, but Changbei's ecological network is more viable from an economic point of view, since it has relatively higher cost efficiency; (3) decrease in patch density, Euclidean nearest neighbor distance, and an increase in mean patch size and connectivity implied that the ecological network

  6. Planning of Green Space Ecological Network in Urban Areas: An Example of Nanchang, China

    Directory of Open Access Journals (Sweden)

    Haifeng Li

    2015-10-01

    Full Text Available Green space plays an important role in sustainable urban development and ecology by virtue of multiple environmental, recreational, and economic benefits. Constructing an effective and harmonious urban ecological network and maintaining a sustainable living environment in response to rapid urbanization are the key issues required to be resolved by landscape planners. In this paper, Nanchang City, China was selected as a study area. Based on a series of landscape metrics, the landscape pattern analysis of the current (in 2005 and planned (in 2020 green space system were, respectively, conducted by using FRAGSTATS 3.3 software. Considering the actual situation of the Nanchang urban area, a “one river and two banks, north and south twin cities” ecological network was constructed by using network analysis. Moreover, the ecological network was assessed by using corridor structure analysis, and the improvement of an ecological network on the urban landscape was quantitatively assessed through a comparison between the ecological network and green space system planning. The results indicated that: (1 compared to the green space system in 2005, the planned green space system in 2020 of the Nanchang urban area will decline in both districts (Changnan and Changbei districts. Meanwhile, an increase in patch density and a decrease in mean patch size of green space patches at the landscape level implies the fragmentation of the urban green space landscape. In other words, the planned green space system does not necessarily improve the present green space system; (2 the ecological network of two districts has high corridor density, while Changnan’s ecological network has higher connectivity, but Changbei’s ecological network is more viable from an economic point of view, since it has relatively higher cost efficiency; (3 decrease in patch density, Euclidean nearest neighbor distance, and an increase in mean patch size and connectivity implied that the

  7. Effective information spreading based on local information in correlated networks

    Science.gov (United States)

    Gao, Lei; Wang, Wei; Pan, Liming; Tang, Ming; Zhang, Hai-Feng

    2016-12-01

    Using network-based information to facilitate information spreading is an essential task for spreading dynamics in complex networks. Focusing on degree correlated networks, we propose a preferential contact strategy based on the local network structure and local informed density to promote the information spreading. During the spreading process, an informed node will preferentially select a contact target among its neighbors, basing on their degrees or local informed densities. By extensively implementing numerical simulations in synthetic and empirical networks, we find that when only consider the local structure information, the convergence time of information spreading will be remarkably reduced if low-degree neighbors are favored as contact targets. Meanwhile, the minimum convergence time depends non-monotonically on degree-degree correlation, and a moderate correlation coefficient results in the most efficient information spreading. Incorporating the local informed density information into contact strategy, the convergence time of information spreading can be further reduced, and be minimized by an moderately preferential selection.

  8. Network structure and institutional complexity in an ecology of water management games

    Directory of Open Access Journals (Sweden)

    Mark Lubell

    2014-12-01

    Full Text Available Social-ecological systems are governed by a complex of ecology of games featuring multiple actors, policy institutions, and issues, and not just single institutions operating in isolation. We update Long's (1958 ecology of games to analyze the coordinating roles of actors and institutions in the context of the ecology of water management games in San Francisco Bay, California. The ecology of games is operationalized as a bipartite network with actors participating in institutions, and exponential random graph models are used to test hypotheses about the structural features of the network. We found that policy coordination is facilitated mostly by federal and state agencies and collaborative institutions that span geographic boundaries. Network configurations associated with closure show the most significant departures from the predicted model values, consistent with the Berardo and Scholz (2010 "risk hypothesis" that closure is important for solving cooperation problems.

  9. Effects of local and global network connectivity on synergistic epidemics

    CERN Document Server

    Broder-Rodgers, David; Taraskin, Sergei N

    2015-01-01

    The effects of local and global connectivity on the spread of synergistic susceptible-infected-removed epidemics were studied in lattice models with infinite- and finite-range rewiring (small-world and small-world-like models). Several effects were found numerically and supported analytically within a simple model: (i) rewiring enhanced resilience to epidemics with strong constructive synergy on networks with high local connectivity; (ii) rewiring enhanced spread of epidemics with destructive or weak constructive synergy on networks with arbitrary local connectivity; (iii) rewiring enhanced spread of epidemics, independent of synergy, in networks with low local connectivity.

  10. Structural complexity, movement bias, and metapopulation extinction risk in dendritic ecological networks

    Science.gov (United States)

    Campbell Grant, Evan H.

    2011-01-01

    Spatial complexity in metacommunities can be separated into 3 main components: size (i.e., number of habitat patches), spatial arrangement of habitat patches (network topology), and diversity of habitat patch types. Much attention has been paid to lattice-type networks, such as patch-based metapopulations, but interest in understanding ecological networks of alternative geometries is building. Dendritic ecological networks (DENs) include some increasingly threatened ecological systems, such as caves and streams. The restrictive architecture of dendritic ecological networks might have overriding implications for species persistence. I used a modeling approach to investigate how number and spatial arrangement of habitat patches influence metapopulation extinction risk in 2 DENs of different size and topology. Metapopulation persistence was higher in larger networks, but this relationship was mediated by network topology and the dispersal pathways used to navigate the network. Larger networks, especially those with greater topological complexity, generally had lower extinction risk than smaller and less-complex networks, but dispersal bias and magnitude affected the shape of this relationship. Applying these general results to real systems will require empirical data on the movement behavior of organisms and will improve our understanding of the implications of network complexity on population and community patterns and processes.

  11. Real-time network traffic classification technique for wireless local area networks based on compressed sensing

    Science.gov (United States)

    Balouchestani, Mohammadreza

    2017-05-01

    Network traffic or data traffic in a Wireless Local Area Network (WLAN) is the amount of network packets moving across a wireless network from each wireless node to another wireless node, which provide the load of sampling in a wireless network. WLAN's Network traffic is the main component for network traffic measurement, network traffic control and simulation. Traffic classification technique is an essential tool for improving the Quality of Service (QoS) in different wireless networks in the complex applications such as local area networks, wireless local area networks, wireless personal area networks, wireless metropolitan area networks, and wide area networks. Network traffic classification is also an essential component in the products for QoS control in different wireless network systems and applications. Classifying network traffic in a WLAN allows to see what kinds of traffic we have in each part of the network, organize the various kinds of network traffic in each path into different classes in each path, and generate network traffic matrix in order to Identify and organize network traffic which is an important key for improving the QoS feature. To achieve effective network traffic classification, Real-time Network Traffic Classification (RNTC) algorithm for WLANs based on Compressed Sensing (CS) is presented in this paper. The fundamental goal of this algorithm is to solve difficult wireless network management problems. The proposed architecture allows reducing False Detection Rate (FDR) to 25% and Packet Delay (PD) to 15 %. The proposed architecture is also increased 10 % accuracy of wireless transmission, which provides a good background for establishing high quality wireless local area networks.

  12. Local distribution and thermal ecology of two intertidal fishes.

    Science.gov (United States)

    Pulgar, Jose M; Bozinovic, Francisco; Ojeda, F Patricio

    2005-02-01

    Geographic variability in the physiological attributes of widely distributed species can be a result of phenotypic plasticity or can reflect evolutionary responses to a particular habitat. In the field, we assessed thermal variability in low and high intertidal pools and the distribution of resident fish species Scartichthys viridis and transitory Girella laevifrons along this vertical intertidal gradient at three localities along the Chilean coast: Antofagasta (the northernmost and warmest habitat), Carrizal Bajo (central coast) and Las Cruces (the southernmost and coldest habitat). In the laboratory, we evaluated the thermal sensitivity of fish captured from each locality. The response to temperature was estimated as the frequency of opercular movements and as thermal selectivity in a gradient; the former being a indirect indicator of energy costs in a particular environment and the latter revealing differential occupation of habitat. Seawater temperature in intertidal pools was greatest at Antofagasta, and within each site was greatest in high intertidal pools. The two intertidal fish species showed opposite patterns of local distribution, with S. viridis primarily inhabiting the lower sectors of the intertidal zone, and G. laevifrons occupying the higher sectors of the intertidal zone. This pattern was consistent for all three localities. Locality was found to be a very important factor determining the frequency of opercular movement and thermal selectivity of both S. viridis and G. laevifrons. Our results suggest that S. viridis and G. laevifrons respond according to: (1) the thermal history of the habitat from which they came, and (2) the immediate physical conditions of their habitat. These results suggest local adaptation rather than plasticity in thermoregulatory and energetic mechanisms.

  13. Global Invader Impact Network (GIIN): toward standardized evaluation of the ecological impacts of invasive plants.

    Science.gov (United States)

    Barney, Jacob N; Tekiela, Daniel R; Barrios-Garcia, Maria Noelia; Dimarco, Romina D; Hufbauer, Ruth A; Leipzig-Scott, Peter; Nuñez, Martin A; Pauchard, Aníbal; Pyšek, Petr; Vítková, Michaela; Maxwell, Bruce D

    2015-07-01

    Terrestrial invasive plants are a global problem and are becoming ubiquitous components of most ecosystems. They are implicated in altering disturbance regimes, reducing biodiversity, and changing ecosystem function, sometimes in profound and irreversible ways. However, the ecological impacts of most invasive plants have not been studied experimentally, and most research to date focuses on few types of impacts, which can vary greatly among studies. Thus, our knowledge of existing ecological impacts ascribed to invasive plants is surprisingly limited in both breadth and depth. Our aim was to propose a standard methodology for quantifying baseline ecological impact that, in theory, is scalable to any terrestrial plant invader (e.g., annual grasses to trees) and any invaded system (e.g., grassland to forest). The Global Invader Impact Network (GIIN) is a coordinated distributed experiment composed of an observational and manipulative methodology. The protocol consists of a series of plots located in (1) an invaded area; (2) an adjacent removal treatment within the invaded area; and (3) a spatially separate uninvaded area thought to be similar to pre-invasion conditions of the invaded area. A standardized and inexpensive suite of community, soil, and ecosystem metrics are collected allowing broad comparisons among measurements, populations, and species. The method allows for one-time comparisons and for long-term monitoring enabling one to derive information about change due to invasion over time. Invader removal plots will also allow for quantification of legacy effects and their return rates, which will be monitored for several years. GIIN uses a nested hierarchical scale approach encompassing multiple sites, regions, and continents. Currently, GIIN has network members in six countries, with new members encouraged. To date, study species include representatives of annual and perennial grasses; annual and perennial forbs; shrubs; and trees. The goal of the GIIN

  14. From GCM Output to Local Hydrologic and Ecological Impacts: Integrating Climate Change Projections into Conservation Lands

    Science.gov (United States)

    Weiss, S. B.; Micheli, L.; Flint, L. E.; Flint, A. L.; Thorne, J. H.

    2014-12-01

    Assessment of climate change resilience, vulnerability, and adaptation options require downscaling of GCM outputs to local scales, and conversion of temperature and precipitation forcings into hydrologic and ecological responses. Recent work in the San Francisco Bay Area, and California demonstrate a practical approach to this process. First, climate futures (GCM x Emissions Scenario) are screened using cluster analysis for seasonal precipitation and temperature, to select a tractable subset of projections that still represent the range of climate projections. Second, monthly climate projections are downscaled to 270m and the Basin Characterization Model (BCM) applied, to generate fine-scale recharge, runoff, actual evapotranspiration (AET), and climatic water deficit (CWD) accounting for soils, bedrock geology, topography, and local climate. Third, annual time-series are used to derive 30-year climatologies and recurrence intervals of extreme events (including multi-year droughts) at the scale of small watersheds and conservation parcels/networks. We take a "scenario-neutral" approach where thresholds are defined for system "failure," such as water supply shortfalls or drought mortality/vegetation transitions, and the time-window for hitting those thresholds is evaluated across all selected climate projections. San Francisco Bay Area examples include drought thresholds (CWD) for specific vegetation-types that identify leading/trailing edges and local refugia, evaluation of hydrologic resources (recharge and runoff) provided by conservation lands, and productivity of rangelands (AET). BCM outputs for multiple futures are becoming available to resource managers through on-line data extraction tools. This approach has wide applicability to numerous resource management issues.

  15. Adaptive localization and tracking of objects in a sensor network

    OpenAIRE

    2014-01-01

    [ANGLÈS] Wireless Sensor Networks (WSNs) are used to monitor physical or environmental conditions, and to pass their data through the network to a central location. These networks have applications in diverse areas including environmental, health monitoring, home automation or military. The devices that form the network have limited resources, such as power and computational capacity.\\par This thesis focus on the localization and tracking problem, presenting a method that can be used with obj...

  16. Evolution of collaboration within the US long term ecological research network

    Science.gov (United States)

    Jeffrey C. Johnson; Robert R. Christian; James W. Brunt; Caleb R. Hickman; Robert B. Waide

    2010-01-01

    The US Long Term Ecological Research (LTER) program began in 1980 with the mission of addressing long-term ecological phenomena through research at individual sites, as well as comparative and synthetic activities among sites. We applied network science measures to assess how the LTER program has achieved its mission using intersite publications as the measure of...

  17. Moving Beyond Neighborhood: Activity Spaces and Ecological Networks As Contexts for Youth Development.

    Science.gov (United States)

    Browning, Christopher R; Soller, Brian

    2014-01-01

    Many scholars, policy analysts, and practitioners agree that neighborhoods are important contexts for urban youth. Yet, despite decades of research, our knowledge of why and how neighborhoods influence the day-to-day lives of youth is still emerging. Theories about neighborhood effects largely assume that neighborhoods operate to influence youth through exposure-based mechanisms. Extant theoretical approaches, however, have neglected the processes by which neighborhood socioeconomic contexts influence the routine spatial exposures-or activity spaces-of urban residents. In this article, we argue that exposure to organizations, institutions, and other settings that characterize individual activity spaces is a key mechanism through which neighborhoods influence youth outcomes. Moreover, we hypothesize that aggregate patterns of shared local exposure-captured by the concept of ecological networks-are influenced by neighborhood socioeconomic characteristics and are independently consequential for neighborhood youth. Neighborhoods in which residents intersect in space more extensively as a result of routine conventional activities will exhibit higher levels of social capital relevant to youth well-being, including (1) familiarity, (2) beneficial (weak) social ties, (3) trust, (4) shared expectations for pro-social youth behavior (collective efficacy), and (5) the capacity for consistent monitoring of public space. We then consider the implications of ecological networks for understanding the complexities of contextual exposure. We specifically discuss the role of embeddedness in ecological communities-that is, clusters of actors and locations that intersect at higher rates-for understanding contextual influences that are inadequately captured by geographically defined neighborhoods. We conclude with an overview of new approaches to data collection that incorporate insights from an activity-space and ecological-network perspective on neighborhood and contextual influences

  18. Status of the Southern Carpathian forests in the long-term ecological research network.

    Science.gov (United States)

    Badea, Ovidiu; Bytnerowicz, Andrzej; Silaghi, Diana; Neagu, Stefan; Barbu, Ion; Iacoban, Carmen; Iacob, Corneliu; Guiman, Gheorghe; Preda, Elena; Seceleanu, Ioan; Oneata, Marian; Dumitru, Ion; Huber, Viorela; Iuncu, Horia; Dinca, Lucian; Leca, Stefan; Taut, Ioan

    2012-12-01

    Air pollution, bulk precipitation, throughfall, soil condition, foliar nutrients, as well as forest health and growth were studied in 2006-2009 in a long-term ecological research (LTER) network in the Bucegi Mountains, Romania. Ozone (O(3)) was high indicating a potential for phytotoxicity. Ammonia (NH(3)) concentrations rose to levels that could contribute to deposition of nutritional nitrogen (N) and could affect biodiversity changes. Higher that 50% contribution of acidic rain (pH Carpathian region levels. The observed nutritional imbalance could have negative effects on forest trees. Health of forests was moderately affected, with damaged trees (crown defoliation >25%) higher than 30%. The observed crown damage was accompanied by the annual volume losses for the entire research forest area up to 25.4%. High diversity and evenness specific to the stand type's structures and local climate conditions were observed within the herbaceous layer, indicating that biodiversity of the vascular plant communities was not compromised.

  19. Local control of cognitive radio networks

    NARCIS (Netherlands)

    Doerr, C.; Grunwald, D.; Sicker, D.C.

    2009-01-01

    In a network deployment, a cognitive radio will have to perform two fundamental tasks. First, each cognitive radio needs to optimize its internal operation, and second, it needs to derive a configuration that will enable and optimize communication with other nodes in the network. This latter require

  20. The Impact of Metagovernance on Local Governance Networks

    DEFF Research Database (Denmark)

    Damgaard, Bodil; Torfing, Jacob

    2011-01-01

    This article analyses the impact of metagovernance on the functioning of local governance networks. It does so by comparing the functioning of four local governance networks in the field of local employment policy in Denmark. Between 2007 and 2009, two of these networks were linked to jobcentres...... in which the municipality and a state agency shared responsibility for employment policy, while the other two were linked to jobcentres in which the municipality had full responsibility. We explore two types of metagovernance that the local governance networks were subject to: general, hands......-off metagovernance consisting of the assignment of full responsibility to the municipality alone, or of shared responsibility to the municipality and the state jointly; and tailored and fine-tuned metagovernance directed towards only one or a few networks and their corresponding jobcentre(s). Our findings suggest...

  1. Local Optima Networks of the Quadratic Assignment Problem

    CERN Document Server

    Daolio, Fabio; Ochoa, Gabriela; Tomassini, Marco

    2011-01-01

    Using a recently proposed model for combinatorial landscapes, Local Optima Networks (LON), we conduct a thorough analysis of two types of instances of the Quadratic Assignment Problem (QAP). This network model is a reduction of the landscape in which the nodes correspond to the local optima, and the edges account for the notion of adjacency between their basins of attraction. The model was inspired by the notion of 'inherent network' of potential energy surfaces proposed in physical-chemistry. The local optima networks extracted from the so called uniform and real-like QAP instances, show features clearly distinguishing these two types of instances. Apart from a clear confirmation that the search difficulty increases with the problem dimension, the analysis provides new confirming evidence explaining why the real-like instances are easier to solve exactly using heuristic search, while the uniform instances are easier to solve approximately. Although the local optima network model is still under development, w...

  2. Effective information spreading based on local information in correlated networks

    CERN Document Server

    Gao, Lei; Pan, Liming; Tang, Ming; Zhang, Hai-Feng

    2016-01-01

    Using network-based information to facilitate information spreading is an essential task for spreading dynamics in complex networks, which will benefit the promotion of technical innovations, healthy behaviors, new products, etc. Focusing on degree correlated networks, we propose a preferential contact strategy based on the local network structure and local informed density to promote the information spreading. During the spreading process, an informed node will preferentially select a contact target among its neighbors, basing on their degrees or local informed densities. By extensively implementing numerical simulations in synthetic and empirical networks, we find that when only consider the local structure information, the convergence time of information spreading will be remarkably reduced if low-degree neighbors are favored as contact targets. Meanwhile, the minimum convergence time depends non-monotonically on degree-degree correlation, and moderate correlation coefficients result in most efficient info...

  3. Toward a Network Perspective of the Study of Resilience in Social-Ecological Systems

    Directory of Open Access Journals (Sweden)

    Ryan R. J. McAllister

    2006-06-01

    Full Text Available Formal models used to study the resilience of social-ecological systems have not explicitly included important structural characteristics of this type of system. In this paper, we propose a network perspective for social-ecological systems that enables us to better focus on the structure of interactions between identifiable components of the system. This network perspective might be useful for developing formal models and comparing case studies of social-ecological systems. Based on an analysis of the case studies in this special issue, we identify three types of social-ecological networks: (1 ecosystems that are connected by people through flows of information or materials, (2 ecosystem networks that are disconnected and fragmented by the actions of people, and (3 artificial ecological networks created by people, such as irrigation systems. Each of these three archytypal social-ecological networks faces different problems that influence its resilience as it responds to the addition or removal of connections that affect its coordination or the diffusion of system attributes such as information or disease.

  4. Urban Ecological Stewardship: Understanding the Structure, Function and Network of Community-based Urban Land Management

    Directory of Open Access Journals (Sweden)

    Lindsay K. Campbell

    2008-01-01

    Full Text Available Urban environmental stewardship activities are on the rise in cities throughout the Northeast. Groups participating in stewardship activities range in age, size, and geography and represent an increasingly complex and dynamic arrangement of civil society, government and business sectors. To better understand the structure, function and network of these community-based urban land managers, an assessment was conducted in 2004 by the research subcommittee of the Urban Ecology Collaborative. The goal of the assessment was to better understand the role of stewardship organizations engaged in urban ecology initiatives in selected major cities in the Northeastern U.S.: Boston, New Haven, New York City, Pittsburgh, Baltimore, and Washington, D.C. A total of 135 active organizations participated in this assessment. Findings include the discovery of a dynamic social network operating within cities, and a reserve of social capital and expertise that could be better utilized. Although often not the primary land owner, stewardship groups take an increasingly significant responsibility for a wide range of land use types including street and riparian corridors, vacant lots, public parks and gardens, green roofs, etc. Responsibilities include the delivery of public programs as well as daily maintenance and fundraising support. While most of the environmental stewardship organizations operate on staffs of zero or fewer than ten, with small cohorts of community volunteers, there is a significant difference in the total amount of program funding. Nearly all respondents agree that committed resources are scarce and insufficient with stewards relying upon and potentially competing for individual donations, local foundations, and municipal support. This makes it a challenge for the groups to grow beyond their current capacity and to develop long-term programs critical to resource management and education. It also fragments groups, making it difficult for planners and

  5. The role of local ecology during hybridization at the initial stages of ecological speciation in a marine snail.

    Science.gov (United States)

    Galindo, J; Martínez-Fernández, M; Rodríguez-Ramilo, S T; Rolán-Alvarez, E

    2013-07-01

    Hybrid zones of ecologically divergent populations are ideal systems to study the interaction between natural selection and gene flow during the initial stages of speciation. Here, we perform an amplified fragment length polymorphism (AFLP) genome scan in parallel hybrid zones between divergent ecotypes of the marine snail Littorina saxatilis, which is considered a model case for the study of ecological speciation. Ridged-Banded (RB) and Smooth-Unbanded (SU) ecotypes are adapted to different shore levels and microhabitats, although they present a sympatric distribution at the mid-shore where they meet and mate (partially assortatively). We used shell morphology, outlier and nonoutlier AFLP loci from RB, SU and hybrid specimens captured in sympatry to determine the level of phenotypic and genetic introgression. We found different levels of introgression at parallel hybrid zones and nonoutlier loci showed more gene flow with greater phenotypic introgression. These results were independent from the phylogeography of the studied populations, but not from the local ecological conditions. Genetic variation at outlier loci was highly correlated with phenotypic variation. In addition, we used the relationship between genetic and phenotypic variation to estimate the heritability of morphological traits and to identify potential Quantitative Trait Loci to be confirmed in future crosses. These results suggest that ecology (exogenous selection) plays an important role in this hybrid zone. Thus, ecologically based divergent natural selection is responsible, simultaneously, for both ecotype divergence and hybridization. On the other hand, genetic introgression occurs only at neutral loci (nonoutliers). In the future, genome-wide studies and controlled crosses would give more valuable information about this process of speciation in the face of gene flow.

  6. Study on Network System Construction of Forest Ecological in Huaining New Town

    Institute of Scientific and Technical Information of China (English)

    HUANGQingfeng; WUZemin; WANGJianan; HUANGChenglin; LIBao; QIANNimiao

    2004-01-01

    Urban forest is an important composition and the window and soul of modern cities, which has a close relationship with ecological environment and investing environment. So urban forest has been constructed in China. Huaining County could hold of the historical opportunity and come up with the great blueprint of forest ecological network system construction for the new town. This paper mainly introduces the guiding ideas, principles, goals and overall layouts of the construction in the new town, and hope that it will be a model for other county-level forest ecological network system construction in China.

  7. Landscape Planning and Ecological Networks. Part B. A Rural System in Nuoro, Sardinia

    Directory of Open Access Journals (Sweden)

    Andrea De Montis

    2014-05-01

    Full Text Available This paper represents the continuation, i.e. Part B, of an homonymous paper aiming at designing an ecological network for the periurban area on the town of Nuoro in central Sardinia. While in Part A we illustrate the methodological premises and introduce a spatial network analysis-based study of a pilot ecological network, in this paper we apply a complex network analysis approach to the construction and characterization of the dynamics of the ecological network of Nuoro.  We are interested in monitoring the performance of the ecological network evolving from a real to a hypothetical scenario, where the two target vegetal species (holm oak and cultivated or wild olive are present in each patch. We focus on global network properties and on three different centrality measures: degree, clustering coefficient, and betweenness centrality. We also take into account the influence of the intensity of the connection (i.e. the weight by introducing the corresponding weighted centrality measures. Through thematic mapping we illustrate the pattern of each centrality indicator throughout the entire pilot set of patches. In this way, we demonstrate how spatial network analysis is useful to monitor the performance of the network and to support decision-making, management, and planning.

  8. Local ecological knowledge on the goliath grouper epinephelus itajara (teleostei: serranidae in southern Brazil

    Directory of Open Access Journals (Sweden)

    Leopoldo Cavaleri Gerhardinger

    Full Text Available The goliath grouper Epinephelus itajara is a large sized (> 400 kg and critically endangered marine fish, which is protected in many countries, including Brazil. Through the application of semi-structured interviews, we investigated the local ecological knowledge of seven fishermen specialist on catching E. itajara from the Babitonga bay, Santa Catarina, Brazil. Local long-line fisheries for E. itajara seemed to be a disappearing tradition in the studied site, with a detailed inherent local ecological knowledge system, which is also being lost. Our study also showed that fishermen engaged in recent fisheries, such as spear-fishing, can also possess a detailed local ecological knowledge system. Through the analysis of fishermen local ecological knowledge, several aspects of E. itajara life history were registered. This species is found in the inner and outer Babitonga bay, from saline waters to areas with a large input of freshwater, and inhabits submerged wooden substrates and artificial reefs such as shipwrecks, mooring pillars and cargo containers. It is known to spawn in December and subsequent summer months in the studied area. Spawning aggregations are usually seen in December (during full moon, being also eventually observed in January and February by our informants. While lobsters, spadefishes and octopuses seem to constitute the most important food items of inner bay E. itajara, outer bay individuals may feed on catfishes, crustaceans and other fish species. The goliath grouper is regarded as pacific and curious fish, but frequently display agonistic behavior in the presence of divers. Based on the perception of well experienced spear fishermen, we hypothesize that E. itajara undertakes seasonal migrations from the inner to the outer bay during summer, and that the studied population is suffering from growth over-fishing. Our data provides a practical evidence of how joining scientific and local ecological knowledge will likely benefit E

  9. Localization in smart dust sensor networks

    NARCIS (Netherlands)

    Kilic, Y.; Meijerink, Arjan; Bentum, Marinus Jan

    2010-01-01

    Our research goal is to design a robust localization system that offers good accuracy even in the harsh indoor and outdoor environments by handling problems in the physical layer. In this respect, localization based on ultra-wide band (UWB) technology with time-based ranging is a good candidate

  10. Learning Local Components to Understand Large Bayesian Networks

    DEFF Research Database (Denmark)

    Zeng, Yifeng; Xiang, Yanping; Cordero, Jorge

    2009-01-01

    Bayesian networks are known for providing an intuitive and compact representation of probabilistic information and allowing the creation of models over a large and complex domain. Bayesian learning and reasoning are nontrivial for a large Bayesian network. In parallel, it is a tough job for users...... (domain experts) to extract accurate information from a large Bayesian network due to dimensional difficulty. We define a formulation of local components and propose a clustering algorithm to learn such local components given complete data. The algorithm groups together most inter-relevant attributes...... in a domain. We evaluate its performance on three benchmark Bayesian networks and provide results in support. We further show that the learned components may represent local knowledge more precisely in comparison to the full Bayesian networks when working with a small amount of data....

  11. Calibration of the National Ecological Observatory Network's Airborne Imaging Spectrometers

    Science.gov (United States)

    Leisso, N.; Kampe, T. U.; Karpowicz, B. M.

    2014-12-01

    The National Ecological Observatory Network (NEON) is currently under construction by the National Science Foundation. NEON is designed to collect data on the causes and responses to change in the observed ecosystem. The observatory will combine site data collected by terrestrial, instrumental, and aquatic observation systems with airborne remote sensing data. The Airborne Observation Platform (AOP) is designed to collect high-resolution aerial imagery, waveform and discrete LiDAR, and high-fidelity imaging spectroscopic data over the NEON sites annually at or near peak-greenness. Three individual airborne sensor packages will be installed in leased Twin Otter aircraft and used to the collect the NEON sites as NEON enters operations. A key driver to the derived remote sensing data products is the calibration of the imaging spectrometers. This is essential to the overall NEON mission to detect changes in the collected ecosystems over the 30-year expected lifetime. The NEON Imaging Spectrometer (NIS) is a Visible and Shortwave Infrared (VSWIR) grating spectrometer designed by NASA JPL. Spectroscopic data is collected at 5-nm intervals from 380-2500-nm. A single 480 by 640 pixel HgCdTe Focal Plane Array collects dispersed light from a grating tuned for efficiency across the solar-reflective utilized in a push-broom configuration. Primary calibration of the NIS consists of the characterizing the FPA behavior, spectral calibration, and radiometric calibration. To this end, NEON is constructing a Sensor Test Facility to calibrate the NEON sensors. This work discusses the initial NIS laboratory calibration and verification using vicarious calibration techniques during operations. Laboratory spectral calibration is based on well-defined emission lines in conjunction with a scanning monochromator to define the individual spectral response functions. A NIST traceable FEL bulb is used to radiometrically calibrate the imaging spectrometer. An On-board Calibration (OBC) system

  12. The Semi-Planned LAN: Prototyping a Local Area Network.

    Science.gov (United States)

    True, John F.; Rosenwald, Judah

    1986-01-01

    Five administrative user departments at San Francisco State University discovered that they had common requirements for office automation and data manipulation that could be addressed with microcomputers. The results of a local area network project are presented. (Author/MLW)

  13. 3Com Etherseries Local Area Network

    Science.gov (United States)

    1989-03-01

    have mail waiting for them the next time they log on the network. Also, the server will notify the sender if the message is undeliverable. Networks with...drive E: contains the volume INBOX which is used as the mailbox on the server to store electronic mail . EtherShare volumes can have three kinds of...numerical order received mail in your INBOX volume. If there is no mail the screen will be blank. Immediately upon starting EMAIL the program will check to

  14. Ecological Network as a Factor in the Development of Tourism of Ukrainian Danube

    Directory of Open Access Journals (Sweden)

    Vyacheslav Todorov

    2015-08-01

    Full Text Available In the article the main components of the structural elements of the regional ecological network are analyzes. The main reserve for increasing the area of ecological network are such lands as pastures and hayfields, lands of water fund, as well as forests and wooded land. The article considers the distribution of the objects of Natural Conservation Fund on the Ukrainian Danube. It was found that the highest percentages of wilderness protection area are in administrative regions that have access to the Black Seas and Danube. It is shown that in the regional network is not fully represented all existing landscapes in the region.

  15. Makeup like a superstar: Deep Localized Makeup Transfer Network

    OpenAIRE

    Liu, Si; Ou, Xinyu; Qian, Ruihe; Wang, Wei; Cao, Xiaochun

    2016-01-01

    In this paper, we propose a novel Deep Localized Makeup Transfer Network to automatically recommend the most suitable makeup for a female and synthesis the makeup on her face. Given a before-makeup face, her most suitable makeup is determined automatically. Then, both the beforemakeup and the reference faces are fed into the proposed Deep Transfer Network to generate the after-makeup face. Our end-to-end makeup transfer network have several nice properties including: (1) with complete functio...

  16. Wireless Local Area Networks: The Next Evolutionary Step.

    Science.gov (United States)

    Wodarz, Nan

    2001-01-01

    The Institute of Electrical and Electronics Engineers recently approved a high-speed wireless standard that enables devices from different manufacturers to communicate through a common backbone, making wireless local area networks more feasible in schools. Schools can now use wireless access points and network cards to provide flexible…

  17. The Local Area Network and the Cooperative Learning Principle.

    Science.gov (United States)

    Sloan, Fred A.; Koohang, Alex A.

    1991-01-01

    Discussion of the advantages of local area networks (LANs) focuses on their use for successful cooperative learning. Individual and group assessment of success are discussed, effects on academic and affective achievement are considered, and computer-assisted instruction (CAI) programs to use with networking are suggested. (19 references) (LRW)

  18. A Geac Local Area Network for the Bobst Library.

    Science.gov (United States)

    Persky, Gail; And Others

    1984-01-01

    Provides detailed description of New York University's (NYU) Bobst Library Local Area Network (LAN), which was designed and implemented by Geac Computers International technical personnel and NYU library systems staff. Definitions of terminology, why the library installed a LAN, planning, network installation, and the LAN configuration and…

  19. Acquisition of CD-ROM Databases for Local Area Networks.

    Science.gov (United States)

    Davis, Trisha L.

    1993-01-01

    Discusses the acquisition of CD-ROM products for local area networks based on experiences at the Ohio State University libraries. Topics addressed include the historical development of CD-ROM acquisitions; database selection, including pricing and subscription options; the ordering process; and network licensing issues. (six references) (LRW)

  20. Local Area Networks for Libraries--Cast and Recast.

    Science.gov (United States)

    Tao, Dorothy S.

    1987-01-01

    Discusses the rationale, methodology, capabilities and problems of a local area network created for the Library Consortium of Health Institutions in Buffalo, using a multi-user microcomputer. The rationale and design of a new network, designed to better meet information and compatibility requirements, are described and suggestions to network…

  1. Local Area Networks: Effective Tools for Special Libraries.

    Science.gov (United States)

    Hoehl, Susan B.

    1988-01-01

    Examines technological changes in the local area network (LAN) of the Health Sciences Library of Allegheny General Hospital during three years of operation and describes the resulting evolution of staff, services, network requirements, budget, and external relationships of the library. LAN expenditures over four years are shown. (1 reference) (MES)

  2. Local Area Network: What Can a Library Do with It?

    Science.gov (United States)

    Dermody, Melinda Bako

    With the ever growing interest that libraries have in the Internet, the potentials of other computer resources may be overlooked or under-utilized. One such resource is the campus local area network (LAN). For libraries, a campus LAN presents possibilities ranging from simple library promotion to networked databases. The Internet provides…

  3. Event localization in underwater wireless sensor networks using Monitoring Courses

    KAUST Repository

    Debont, Matthew John Robert

    2012-08-01

    We propose m-courses (Monitoring Courses), a novel solution to localize events in an underwater wireless sensor network. These networks consists of surface gateways and relay nodes. GPS can localize the position of surface gateways which can then distribute their locations through the network using acoustic modems. Relay nodes are deployed to remain static, but these untethered nodes may drift due to water currents, resulting in disruption of communication links. We develop a novel underwater alarm system using a cyclic graph model. In the event of link failure, a series of alarm packets are broadcast in the network. These alarms are then captured by the underwater m-courses, which can also be used to assure network connectivity and identify node failures. M-courses also allow the network to localize events and identify network issues locally before forwarding results upwards to a Surface Gateway node. This reduces communication overhead and allows for efficient management of nodes in a mobile network. Our results show that m-course routing reduces the number of sends required to report an event to a Surface Gateway by up to 80% when compared to a naïve routing implementation.

  4. Wireless Local Area Network (WLAN) Vulnerability Assessment and Security

    Science.gov (United States)

    2005-09-01

    vulnerability assessment capability within the Marine Corps. 15. NUMBER OF PAGES 177 14. SUBJECT TERMS Wireless Local Area Network (WLAN), WiFi ... WiFi Protected Access xviii THIS PAGE INTENTIONALLY LEFT BLANK xix...intelligence officers in how to hack into U.S. computers2. Government networks, proprietary commercial information, and scientific research are all

  5. Binaural Sound Localization Using Neural Networks

    Science.gov (United States)

    1991-12-12

    by Brennan, involved the implementation of a neural network to model the ability of a bat to discriminate between a mealworm and an inedible object...locate, identify and capture airborne prey (6:2). The sonar returns were collected from the mealworms , spheres and disks at various rotations (90 to

  6. Local Geostatistical Models and Big Data in Hydrological and Ecological Applications

    Science.gov (United States)

    Hristopulos, Dionissios

    2015-04-01

    The advent of the big data era creates new opportunities for environmental and ecological modelling but also presents significant challenges. The availability of remote sensing images and low-cost wireless sensor networks implies that spatiotemporal environmental data to cover larger spatial domains at higher spatial and temporal resolution for longer time windows. Handling such voluminous data presents several technical and scientific challenges. In particular, the geostatistical methods used to process spatiotemporal data need to overcome the dimensionality curse associated with the need to store and invert large covariance matrices. There are various mathematical approaches for addressing the dimensionality problem, including change of basis, dimensionality reduction, hierarchical schemes, and local approximations. We present a Stochastic Local Interaction (SLI) model that can be used to model local correlations in spatial data. SLI is a random field model suitable for data on discrete supports (i.e., regular lattices or irregular sampling grids). The degree of localization is determined by means of kernel functions and appropriate bandwidths. The strength of the correlations is determined by means of coefficients. In the "plain vanilla" version the parameter set involves scale and rigidity coefficients as well as a characteristic length. The latter determines in connection with the rigidity coefficient the correlation length of the random field. The SLI model is based on statistical field theory and extends previous research on Spartan spatial random fields [2,3] from continuum spaces to explicitly discrete supports. The SLI kernel functions employ adaptive bandwidths learned from the sampling spatial distribution [1]. The SLI precision matrix is expressed explicitly in terms of the model parameter and the kernel function. Hence, covariance matrix inversion is not necessary for parameter inference that is based on leave-one-out cross validation. This property

  7. Event Localization in Underwater Wireless Sensor Networks using Monitoring Courses

    KAUST Repository

    Debont, Matthew

    2011-11-01

    In this thesis we consider different methods to localize events in a multi-hop wireless sensor network operating underwater using acoustic modems. The network consists of surface gateway nodes and relay nodes. Localization of surface gateways can be achieved through GPS, but we cannot rely on this technology for localizing underwater nodes. Surface Gateway nodes can distribute their locations through the network using the incoming signals by the acoustic modems from the relay nodes. Relay nodes are deployed to remain static but due to water currents, floating, and the untethered nature of the nodes, they often suffer from frequent drifting which can result in a deployed network suffering link failures. In this work, we developed a novel concept of an underwater alarming system, which adapts a cyclic graph model. In the event of link failure, a series of alarm packets are broadcasted in the network. These alarms are then captured through a novel concept of underwater Monitoring Courses (M-Courses), which can also be used to assure network connectivity and identify node faults. M-Courses also allow the network to localize events and identify network issues at a local level before forwarding any results upwards to a Surface Gateway nodes. This reduces the amount of communication overhead needed and allowing for distributed management of nodes in a network which may be constantly moving. We show that the proposed algorithms can reduce the number of send operations needed for an event to be localized in a network. We have found that M-Course routing reduces the number of sends required to report an event to a Surface Gateway by up to 80% in some cases when compared to a naive routing implementation. But this is achieved by increasing the time for an event to reach a Surface Gateway. These effects are both due to the buffering effect of M-Course routing, which allows us to efficiently deal with multiple events in an local area and we find that the performance of M

  8. Localization in Wireless Networks Foundations and Applications

    CERN Document Server

    Sanford, Jessica Feng; Slijepcevic, Sasha

    2012-01-01

    In a computational tour-de-force, this volume wipes away a host of problems related to location discovery in wireless ad-hoc sensor networks. WASNs have recognized potential in many applications that are location-dependent, yet are heavily constrained by factors such as cost and energy consumption. Their “ad-hoc” nature, with direct rather than mediated connections between a network of wireless devices, adds another layer of difficulty.   Basing this work entirely on data-driven, coordinated algorithms, the authors' aim is to present location discovery techniques that are highly accurate—and which fit user criteria. The research deploys nonparametric statistical methods and relies on the concept of joint probability to construct error (including location error) models and environmental field models. It also addresses system issues such as the broadcast and scheduling of the beacon. Reporting an impressive accuracy gain of almost 17 percent, and organized in a clear, sequential manner, this book represe...

  9. Global efficiency of local immunization on complex networks

    CERN Document Server

    Hébert-Dufresne, Laurent; Young, Jean-Gabriel; Dubé, Louis J

    2012-01-01

    Epidemics occur in all shapes and forms: infections propagating in our sparse sexual networks, information spreading through our much denser social interactions, or viruses circulating on the Internet. With the advent of large databases and efficient analysis algorithms, these processes can be better predicted and controlled. In this study, we use different characteristics of network organization to identify the influential spreaders in networks of diverse nature. We propose a local measure of node influence based on the network's community structure which is easily estimated in real systems and frequently outperforms the usual measure of a node's importance. More importantly, through an extensive study spanning 17 empirical networks and 2 epidemic models, we formulate a readily applicable approach which proves efficient even though different networks and different diseases require different strategies.This research is expected to guide efforts regarding public health policies, computer network security and t...

  10. Secure Localization and Tracking in Sensor Networks

    Science.gov (United States)

    2008-01-01

    To my parents, Yurng-Der Chang and Shiu-Mei Lee iii Biography Chih-Chieh Geoff Chang was born and raised in a beautiful resort town, Hualien, Taiwan...manufacturing and application needs. Currently, companies like Arch Rock, Crossbow, Dust Networks, Millennial Net, and Moteiv offer various types of sensor...activate one sensor node to make the measurement. This is the beauty of target tracking algorithms. Armed with the known models in (3.1) and (3.2), and

  11. Image-based Localization using Hourglass Networks

    OpenAIRE

    Melekhov, Iaroslav; Ylioinas, Juha; Kannala, Juho; Rahtu, Esa

    2017-01-01

    In this paper, we propose an encoder-decoder convolutional neural network (CNN) architecture for estimating camera pose (orientation and location) from a single RGB-image. The architecture has a hourglass shape consisting of a chain of convolution and up-convolution layers followed by a regression part. The up-convolution layers are introduced to preserve the fine-grained information of the input image. Following the common practice, we train our model in end-to-end manner utilizing transfer ...

  12. Automated Bilingual Circulation System Using PC Local Area Networks.

    Science.gov (United States)

    Iskanderani, A. I.; Anwar, M. A.

    1992-01-01

    Describes a local automated bilingual circulation system using personal computers in a local area network that was developed at King Abdulaziz University (Saudi Arabia) for Arabic and English materials. Topics addressed include the system structure, hardware, major features, storage requirements, and costs. (nine references) (LRW)

  13. Study on the Cost Calculation of Local Fixed Telecom Network Based on Unbundled Network Elements

    Institute of Scientific and Technical Information of China (English)

    XU Liang; LIANG Xiong-jian; HUANG Xiu-qing

    2005-01-01

    In this paper, according to the practical condition of local fixed telecom network, based on the method of the realistic total element long-run incremental cost, the practical methods of dividing the network elements, calculating the cost of network elements and services are given, to provide reference for the cost calculation in telecom industry.

  14. Distributed Source Localization in Wireless Underground Sensor Networks

    CERN Document Server

    Chen, Hongyang; Wang, Chen

    2011-01-01

    Node localization plays an important role in many practical applications of wireless underground sensor networks (WUSNs), such as finding the locations of earthquake epicenters, underground explosions, and microseismic events in mines. It is more difficult to obtain the time-difference-of-arrival (TDOA) measurements in WUSNs than in terrestrial wireless sensor networks because of the unfavorable channel characteristics in the underground environment. The robust Chinese remainder theorem (RCRT) has been shown to be an effective tool for solving the phase ambiguity problem and frequency estimation problem in wireless sensor networks. In this paper, the RCRT is used to robustly estimate TDOA or range difference in WUSNs and therefore improves the ranging accuracy in such networks. After obtaining the range difference, distributed source localization algorithms based on a diffusion strategy are proposed to decrease the communication cost while satisfying the localization accuracy requirement. Simulation results c...

  15. Local-scale models reveal ecological niche variability in amphibian and reptile communities from two contrasting biogeographic regions

    Directory of Open Access Journals (Sweden)

    Alberto Muñoz

    2016-10-01

    Full Text Available Ecological Niche Models (ENMs are widely used to describe how environmental factors influence species distribution. Modelling at a local scale, compared to a large scale within a high environmental gradient, can improve our understanding of ecological species niches. The main goal of this study is to assess and compare the contribution of environmental variables to amphibian and reptile ENMs in two Spanish national parks located in contrasting biogeographic regions, i.e., the Mediterranean and the Atlantic area. The ENMs were built with maximum entropy modelling using 11 environmental variables in each territory. The contributions of these variables to the models were analysed and classified using various statistical procedures (Mann–Whitney U tests, Principal Components Analysis and General Linear Models. Distance to the hydrological network was consistently the most relevant variable for both parks and taxonomic classes. Topographic variables (i.e., slope and altitude were the second most predictive variables, followed by climatic variables. Differences in variable contribution were observed between parks and taxonomic classes. Variables related to water availability had the larger contribution to the models in the Mediterranean park, while topography variables were decisive in the Atlantic park. Specific response curves to environmental variables were in accordance with the biogeographic affinity of species (Mediterranean and non-Mediterranean species and taxonomy (amphibians and reptiles. Interestingly, these results were observed for species located in both parks, particularly those situated at their range limits. Our findings show that ecological niche models built at local scale reveal differences in habitat preferences within a wide environmental gradient. Therefore, modelling at local scales rather than assuming large-scale models could be preferable for the establishment of conservation strategies for herptile species in natural

  16. Cascading failures in local-world evolving networks

    Institute of Scientific and Technical Information of China (English)

    Zhe-jing BAO; Yi-jia CAO

    2008-01-01

    The local-world (LW) evolving network model shows a transition for the degree distribution between the exponential and power-law distributions, depending on the LW size. Cascading failures under intentional attacks in LW network models with different LW sizes were investigated using the cascading failures load model. We found that the LW size has a significant impact on the network's robustness against deliberate attacks. It is much easier to trigger cascading failures in LW evolving networks with a larger LW size. Therefore, to avoid cascading failures in real networks with local preferential attachment such as the Internet, the World Trade Web and the multi-agent system, the LW size should be as small as possible.

  17. Generating weighted community networks based on local events

    Institute of Scientific and Technical Information of China (English)

    Xu Qi-Xin; Xu Xin-Jian

    2009-01-01

    realistic networks have community structures, namely, a network consists of groups of nodes within which links are dense but among which links are sparse. This paper proposes a growing network model based on local processes, the addition of new nodes intra-community and new links intra- or inter-community. Also, it utilizes the preferential attachment for building connections determined by nodes' strengths, which evolves dynamically during the growth of the system. The resulting network reflects the intrinsic community structure with generalized power-law distributions of nodes' degrees and strengths.

  18. Energy spectrum for a strongly correlated network and local magnetism

    Institute of Scientific and Technical Information of China (English)

    Li-li LIU; Qiao BI

    2009-01-01

    In this work, we consider a quantum strongly correlated network described by an Anderson s-d mixing model. By introducing the Green function on the projected formalism of the Schrieffer and Wolf transformation, the energy spectrum of the system can be obtained. Using this result we calculate the survivability distribution of the network and discuss the local magnetism in the network, which shows that the survivability is an important statistical characteristic quantity not just to reflect the network topological property but also dynamics.

  19. Cooperative Localization and Tracking in Distributed Robot-Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fan; Guilherme S.Pereira; Vijay Kumar

    2005-01-01

    This paper addresses the problem of real-time position and orientation estimation of networked mobile robots in two-dimensional Euclidean space with simultaneous tracking of a rigid unknown object based on exteroceptive sensory information extracted from distributed vision systems. The sufficient and necessary conditions for team localization are proposed. A localization and object tracking approach based on statistical operators and graph searching algorithms is presented for a team of robots localized with heterogeneous sensors. The approach was implemented in an experimental platform consisting of car-like mobile robots equipped with omnidirectional video cameras and IEEE 802.11b wireless networking. The experimental results validate the approach.

  20. Global and local knowledge networks in innovation

    DEFF Research Database (Denmark)

    Lorentzen, Anne

    2006-01-01

    Ideas of learning regions and regional innovation systems and innovation networks have for long been in focus in economic geography. The importance of geographic proximity between innovating partners is widely unquestioned and documented by studies of high-tech areas in advanced countries. Not much...... has been said until now about the pattern of cooperation among firms in low and medium tech industry in more peripheral locations. What patterns of knowledge sourcing can be detected in such industries? The article detects the pattern and role of knowledge sourcing of such firms. It looks at the type...

  1. A newself-localization method for wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Many applications of wireless sensor networks can benefit from fine-grained localization. In this paper, we proposed an accurate, distributed localization method based on the time difference between radio signal and sound wave. In a trilateration, each node adaptively chooses a neighborhood of sensors and updates its position estimate with trilateration, and then passes this update to neighboring sensors. Application examples demonstrate that the proposed method is more robust and accurate in localizing nod...

  2. Schedule-based sequential localization in asynchronous wireless networks

    Science.gov (United States)

    Zachariah, Dave; De Angelis, Alessio; Dwivedi, Satyam; Händel, Peter

    2014-12-01

    In this paper, we consider the schedule-based network localization concept, which does not require synchronization among nodes and does not involve communication overhead. The concept makes use of a common transmission sequence, which enables each node to perform self-localization and to localize the entire network, based on noisy propagation-time measurements. We formulate the schedule-based localization problem as an estimation problem in a Bayesian framework. This provides robustness with respect to uncertainty in such system parameters as anchor locations and timing devices. Moreover, we derive a sequential approximate maximum a posteriori (AMAP) estimator. The estimator is fully decentralized and copes with varying noise levels. By studying the fundamental constraints given by the considered measurement model, we provide a system design methodology which enables a scalable solution. Finally, we evaluate the performance of the proposed AMAP estimator by numerical simulations emulating an impulse-radio ultra-wideband (IR-UWB) wireless network.

  3. A local-world node deleting evolving network model

    Energy Technology Data Exchange (ETDEWEB)

    Gu Yuying [Department of Mathematics, Tongji University, Shanghai 200092 (China); Sun Jitao [Department of Mathematics, Tongji University, Shanghai 200092 (China)], E-mail: sunjt@sh163.net

    2008-06-16

    A new type network growth rule which comprises node addition with the concept of local-world connectivity and node deleting is studied. A series of theoretical analysis and numerical simulation to the LWD network are conducted in this Letter. Firstly, the degree distribution p(k) of this network changes no longer pure scale free but truncates by an exponential tail and the truncation in p(k) increases as p{sub a} decreases. Secondly, the connectivity is tighter, as the local-world size M increases. Thirdly, the average path length L increases and the clustering coefficient decreases as generally node deleting increases. Finally, trends up when the local-world size M increases, so as to k{sub max}. Hence, the expanding local-world can compensate the infection of the node deleting.

  4. Mapping green infrastructure based on ecosystem services and ecological networks. A Pan-European case study

    OpenAIRE

    LIQUETE GARCIA MARIA DEL CAMINO; KLEESCHULTE Stefan; DIGE Gorm; MAES JOACHIM; Grizzetti, Bruna; Olah, Branislav; ZULIAN GRAZIA

    2014-01-01

    Identifying, promoting and preserving a strategically planned green infrastructure (GI) network can provide ecological, economic and social benefits. It has also become a priority for the planning and decision-making process in sectors such as conservation, (land) resource efficiency, agriculture, forestry or urban development. In this paper we propose a methodology that can be used to identify and map GI elements at landscape level based on the notions of ecological connectivity, multi-fu...

  5. The evolutionary and ecological consequences of animal social networks: emerging issues.

    Science.gov (United States)

    Kurvers, Ralf H J M; Krause, Jens; Croft, Darren P; Wilson, Alexander D M; Wolf, Max

    2014-06-01

    The first generation of research on animal social networks was primarily aimed at introducing the concept of social networks to the fields of animal behaviour and behavioural ecology. More recently, a diverse body of evidence has shown that social fine structure matters on a broader scale than initially expected, affecting many key ecological and evolutionary processes. Here, we review this development. We discuss the effects of social network structure on evolutionary dynamics (genetic drift, fixation probabilities, and frequency-dependent selection) and social evolution (cooperation and between-individual behavioural differences). We discuss how social network structure can affect important coevolutionary processes (host-pathogen interactions and mutualisms) and population stability. We also discuss the potentially important, but poorly studied, role of social network structure on dispersal and invasion. Throughout, we highlight important areas for future research.

  6. Ecological networks are more sensitive to plant than to animal extinction under climate change

    Science.gov (United States)

    Schleuning, Matthias; Fründ, Jochen; Schweiger, Oliver; Welk, Erik; Albrecht, Jörg; Albrecht, Matthias; Beil, Marion; Benadi, Gita; Blüthgen, Nico; Bruelheide, Helge; Böhning-Gaese, Katrin; Dehling, D. Matthias; Dormann, Carsten F.; Exeler, Nina; Farwig, Nina; Harpke, Alexander; Hickler, Thomas; Kratochwil, Anselm; Kuhlmann, Michael; Kühn, Ingolf; Michez, Denis; Mudri-Stojnić, Sonja; Plein, Michaela; Rasmont, Pierre; Schwabe, Angelika; Settele, Josef; Vujić, Ante; Weiner, Christiane N.; Wiemers, Martin; Hof, Christian

    2016-01-01

    Impacts of climate change on individual species are increasingly well documented, but we lack understanding of how these effects propagate through ecological communities. Here we combine species distribution models with ecological network analyses to test potential impacts of climate change on >700 plant and animal species in pollination and seed-dispersal networks from central Europe. We discover that animal species that interact with a low diversity of plant species have narrow climatic niches and are most vulnerable to climate change. In contrast, biotic specialization of plants is not related to climatic niche breadth and vulnerability. A simulation model incorporating different scenarios of species coextinction and capacities for partner switches shows that projected plant extinctions under climate change are more likely to trigger animal coextinctions than vice versa. This result demonstrates that impacts of climate change on biodiversity can be amplified via extinction cascades from plants to animals in ecological networks. PMID:28008919

  7. PlayNCool: Opportunistic Network Coding for Local Optimization of Routing in Wireless Mesh Networks

    DEFF Research Database (Denmark)

    Pahlevani, Peyman; Roetter, Daniel Enrique Lucani; Pedersen, Morten Videbæk;

    2013-01-01

    This paper introduces PlayNCool, an opportunistic protocol with local optimization based on network coding to increase the throughput of a wireless mesh network (WMN). PlayNCool aims to enhance current routing protocols by (i) allowing random linear network coding transmissions end-to-end, (ii...... in large scale mesh networks. We show that PlayNCool can provide gains of more than 3x in individual links, which translates into a large end-to-end throughput improvement, and that it provides higher gains when more nodes in the network contend for the channel at the MAC layer, making it particularly...... relevant for dense mesh networks....

  8. Local dynamics of gap-junction-coupled interneuron networks

    Science.gov (United States)

    Lau, Troy; Gage, Gregory J.; Berke, Joshua D.; Zochowski, Michal

    2010-03-01

    Interneurons coupled by both electrical gap-junctions (GJs) and chemical GABAergic synapses are major components of forebrain networks. However, their contributions to the generation of specific activity patterns, and their overall contributions to network function, remain poorly understood. Here we demonstrate, using computational methods, that the topological properties of interneuron networks can elicit a wide range of activity dynamics, and either prevent or permit local pattern formation. We systematically varied the topology of GJ and inhibitory chemical synapses within simulated networks, by changing connection types from local to random, and changing the total number of connections. As previously observed we found that randomly coupled GJs lead to globally synchronous activity. In contrast, we found that local GJ connectivity may govern the formation of highly spatially heterogeneous activity states. These states are inherently temporally unstable when the input is uniformly random, but can rapidly stabilize when the network detects correlations or asymmetries in the inputs. We show a correspondence between this feature of network activity and experimental observations of transient stabilization of striatal fast-spiking interneurons (FSIs), in electrophysiological recordings from rats performing a simple decision-making task. We suggest that local GJ coupling enables an active search-and-select function of striatal FSIs, which contributes to the overall role of cortical-basal ganglia circuits in decision-making.

  9. Effects of local and global network connectivity on synergistic epidemics

    Science.gov (United States)

    Broder-Rodgers, David; Pérez-Reche, Francisco J.; Taraskin, Sergei N.

    2015-12-01

    Epidemics in networks can be affected by cooperation in transmission of infection and also connectivity between nodes. An interplay between these two properties and their influence on epidemic spread are addressed in the paper. A particular type of cooperative effects (called synergy effects) is considered, where the transmission rate between a pair of nodes depends on the number of infected neighbors. The connectivity effects are studied by constructing networks of different topology, starting with lattices with only local connectivity and then with networks that have both local and global connectivity obtained by random bond-rewiring to nodes within a certain distance. The susceptible-infected-removed epidemics were found to exhibit several interesting effects: (i) for epidemics with strong constructive synergy spreading in networks with high local connectivity, the bond rewiring has a negative role in epidemic spread, i.e., it reduces invasion probability; (ii) in contrast, for epidemics with destructive or weak constructive synergy spreading on networks of arbitrary local connectivity, rewiring helps epidemics to spread; (iii) and, finally, rewiring always enhances the spread of epidemics, independent of synergy, if the local connectivity is low.

  10. Distributed localization for anchor-free sensor networks

    Institute of Scientific and Technical Information of China (English)

    Cui Xunxue; Shan Zhiguan; Liu Jianjun

    2008-01-01

    Geographic location of nodes is very useful in a sensor network. Previous localization algorithms assume that there exist some anchor nodes in this kind of network, and then other nodes are estimated to create their coordinates. Once there are not anchors to be deployed, those localization algorithms will be invalidated. Many papers in this field focus on anchor-based solutions. The use of anchors introduces many limitations, since anchors require external equipments such as global position system, cause additional power consumption. A novel positioning algorithm is proposed to use a virtual coordinate system based on a new concept-virtual anchor. It is executed in a distributed fashion according to the connectivity of a node and the measured distances to its neighbors. Both the adjacent member information and the ranging distance result are combined to generate the estimated position of a network, one of which is independently adopted for localization previously. At the position refinement stage the intermediate estimation of a node begins to be evaluated on its reliability for position mutation; thus the positioning optimization process of the whole network is avoided falling into a local optimal solution. Simulation results prove that the algorithm can resolve the distributed localization problem for anchor-free sensor networks, and is superior to previous methods in terms of its positioning capability under a variety of circumstances.

  11. Limitations of a metabolic network-based reverse ecology method for inferring host-pathogen interactions.

    Science.gov (United States)

    Takemoto, Kazuhiro; Aie, Kazuki

    2017-05-25

    Host-pathogen interactions are important in a wide range of research fields. Given the importance of metabolic crosstalk between hosts and pathogens, a metabolic network-based reverse ecology method was proposed to infer these interactions. However, the validity of this method remains unclear because of the various explanations presented and the influence of potentially confounding factors that have thus far been neglected. We re-evaluated the importance of the reverse ecology method for evaluating host-pathogen interactions while statistically controlling for confounding effects using oxygen requirement, genome, metabolic network, and phylogeny data. Our data analyses showed that host-pathogen interactions were more strongly influenced by genome size, primary network parameters (e.g., number of edges), oxygen requirement, and phylogeny than the reserve ecology-based measures. These results indicate the limitations of the reverse ecology method; however, they do not discount the importance of adopting reverse ecology approaches altogether. Rather, we highlight the need for developing more suitable methods for inferring host-pathogen interactions and conducting more careful examinations of the relationships between metabolic networks and host-pathogen interactions.

  12. Using Local Ecological Knowledge and Environmental Education in Resource Management of Abalone in Carot, Anda, Pangasinan

    Directory of Open Access Journals (Sweden)

    Emmanuel C. Capinpin, Jr.

    2012-06-01

    Full Text Available The objectives of the present study were to (1 determine the local ecological knowledge (LEK of abalone gatherers through interviews and mentoring, and assess the correspondence between scientific information and LEK, so that areas where local knowledge may be most useful in resource management could be identified, and (2 to empower selected gatherers/farmers with knowledge and technical skills through environmental education to help develop or build their capacity to become sustainable resource managers. The LEK of abalone fishers was determined using three complementary approaches – group interview, individual interview, and mentoring sessions. Local fishers possess a wealth of knowledge about the interactions of species gained through many years of observations, and this knowledge may be useful in guiding biologists in ecological restoration or management regimes. Additionally, the fishers’ LEK, validated by modern scientific ecological findings, could be a source of important and effective ideas in resource management. The knowledge of the abalone gatherers about important abalone fishing grounds should help in pinpointing critical areas that need to be managed. Abalone mariculture in cages should be set up in these areas to routinely create dense breeding populations which can help in enhancing recovery and in providing fishers with a source of additional income. The continued enforcement of marine protected areas and the periodic release or reseeding of abalone in sanctuaries could also be considered viable resource management options. Other recommendations for resource management based on gathered local knowledge and lessons learned from the environmental education (EE seminars are also presented.

  13. Local perceptions on social-ecological dynamics in Latin America in three community-based natural resource management systems

    Directory of Open Access Journals (Sweden)

    Maria del Mar Delgado-Serrano

    2015-12-01

    Full Text Available Several examples of community-based natural resource management in Latin American social-ecological systems exist in which communities control the management of common-pool resources. Understanding community perceptions of the performance of these systems is essential to involve communities in sustainable management strategies. In this analysis of three areas in Colombia, Mexico, and Argentina, we analyzed the local perceptions of the social and environmental challenges faced by these social-ecological systems and how these challenges and drivers affect their resilience. To do this, we combined prospective structural analysis to unravel stakeholders' perceptions of each system's functioning along with network analysis to assess resilience. We identified external variables as the most influential variables in the Colombian and Argentine cases. In the Mexican case, larger influence is exerted by internal variables, particularly those linked to the governance system. The case study analysis revealed that the community-based natural resource management approach needs external support and recognition to work effectively. In the Argentine and Colombian cases, megaprojects were perceived as controllers with medium or strong influence but low dependence. The use of ancestral knowledge (Colombia, the history of land use (Mexico, and the history of the artisanal fishery (Argentina were all perceived as common challenges to community-based natural resource management. In terms of social-ecological resilience, framed within the three-dimensional model of the adaptive cycle, all three social-ecological systems were considered to be highly connected and resilient but with different degrees of capacity or cumulative potential.

  14. A local immunization strategy for networks with overlapping community structure

    Science.gov (United States)

    Taghavian, Fatemeh; Salehi, Mostafa; Teimouri, Mehdi

    2017-02-01

    Since full coverage treatment is not feasible due to limited resources, we need to utilize an immunization strategy to effectively distribute the available vaccines. On the other hand, the structure of contact network among people has a significant impact on epidemics of infectious diseases (such as SARS and influenza) in a population. Therefore, network-based immunization strategies aim to reduce the spreading rate by removing the vaccinated nodes from contact network. Such strategies try to identify more important nodes in epidemics spreading over a network. In this paper, we address the effect of overlapping nodes among communities on epidemics spreading. The proposed strategy is an optimized random-walk based selection of these nodes. The whole process is local, i.e. it requires contact network information in the level of nodes. Thus, it is applicable to large-scale and unknown networks in which the global methods usually are unrealizable. Our simulation results on different synthetic and real networks show that the proposed method outperforms the existing local methods in most cases. In particular, for networks with strong community structures, high overlapping membership of nodes or small size communities, the proposed method shows better performance.

  15. Seahorses in focus: local ecological knowledge of seahorse-watching operators in a tropical estuary.

    Science.gov (United States)

    Ternes, Maria L F; Gerhardinger, Leopoldo C; Schiavetti, Alexandre

    2016-11-08

    Seahorses are endangered teleost fishes under increasing human pressures worldwide. In Brazil, marine conservationists and policy-makers are thus often skeptical about the viability of sustainable human-seahorse interactions. This study focuses on local ecological knowledge on seahorses and the implications of their non-lethal touristic use by a coastal community in northeastern Brazil. Community-based seahorse-watching activities have been carried out in Maracaípe village since 1999, but remained uninvestigated until the present study. Our goal is to provide ethnoecological understanding on this non-extractive use to support seahorse conservation and management. We interviewed 32 informants through semi-structured questionnaires to assess their socioeconomic profile, their knowledge on seahorse natural history traits, human uses, threats and abundance trends. Seahorse-watching has high socioeconomic relevance, being the primary income source for all respondents. Interviewees elicited a body of knowledge on seahorse biology largely consistent with up-to-date research literature. Most informants (65.5 %) perceived no change in seahorse abundance. Their empirical knowledge often surpassed scientific reports, i.e. through remarks on trophic ecology; reproductive aspects, such as, behavior and breeding season; spatial and temporal distribution, suggesting seahorse migration related to environmental parameters. Seahorse-watching operators were aware of seahorse biological and ecological aspects. Despite the gaps remaining on biological data about certain seahorse traits, the respondents provided reliable information on all questions, adding ethnoecological remarks not yet assessed by conventional scientific surveys. We provide novel ethnobiological insight on non-extractive modes of human-seahorse interaction, eliciting environmental policies to integrate seahorse conservation with local ecological knowledge and innovative ideas for seahorse sustainable use. Our study

  16. Local densities connect spatial ecology to game, multilevel selection and inclusive fitness theories of cooperation.

    Science.gov (United States)

    Tekwa, Edward W; Gonzalez, Andrew; Loreau, Michel

    2015-09-07

    Cooperation plays a crucial role in many aspects of biology. We use the spatial ecological metrics of local densities to measure and model cooperative interactions. While local densities can be found as technical details in current theories, we aim to establish them as central to an approach that describes spatial effects in the evolution of cooperation. A resulting local interaction model neatly partitions various spatial and non-spatial selection mechanisms. Furthermore, local densities are shown to be fundamental for important metrics of game theory, multilevel selection theory and inclusive fitness theory. The corresponding metrics include structure coefficients, spatial variance, contextual covariance, relatedness, and inbreeding coefficient or F-statistics. Local densities serve as the basis of an emergent spatial theory that draws from and brings unity to multiple theories of cooperation.

  17. Learning without local minima in radial basis function networks.

    Science.gov (United States)

    Bianchini, M; Frasconi, P; Gori, M

    1995-01-01

    Learning from examples plays a central role in artificial neural networks. The success of many learning schemes is not guaranteed, however, since algorithms like backpropagation may get stuck in local minima, thus providing suboptimal solutions. For feedforward networks, optimal learning can be achieved provided that certain conditions on the network and the learning environment are met. This principle is investigated for the case of networks using radial basis functions (RBF). It is assumed that the patterns of the learning environment are separable by hyperspheres. In that case, we prove that the attached cost function is local minima free with respect to all the weights. This provides us with some theoretical foundations for a massive application of RBF in pattern recognition.

  18. Weighted Networks Model Based on Traffic Dynamics with Local Perturbation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    In the study of weighted complex networks, the interplay between traffic and topology have been paid much attention. However, the variation of topology and weight brought by new added vertices or edges should also be considered. In this paper, an evolution model of weighted networks driven by traffic dynamics with local perturbation is proposed. The model gives power-law distribution of degree, weight and strength, as confirmed by empirical measurements. By choosing appropriate parameters W and δ, the exponents of various power law distributions can be adjusted to meet real world networks. Nontrivial clustering coefficient C, degree assortativity coefficient r, and strength-degree correlation are also considered. What should be emphasized is that, with the consideration of local perturbation, one can adjust the exponent of strength-degree correlation more effectively. It makes our model more general than previous ones and may help reproducing real world networks more appropriately.

  19. Quantify and Maximise Global Viral Influence Through Local Network Information

    CERN Document Server

    Hu, Yanqing; Feng, Ling; Jin, Yuliang

    2015-01-01

    Measuring and maximising the influence of individuals is the key to understand and leverage the multiplicative potential of viral spreading over social networks. Yet these have been recognized as problems requiring global structural information, and extremely difficult for the enormous size and complexity of online social networks. Based on the percolation phenomenon, we show that they can be essentially reduced to local problems. Our estimated global influence of individuals based on local structural information matches that of brute-force search. Furthermore this measure leads to an efficient algorithm to identify the best seed spreaders for maximum viral influence. Its time complexity is independent of network size, making it practically useful for real networks. The underlying theoretical framework enables a thorough analytical assessment of the prediction accuracy and the absolute performance of the proposed methods.

  20. Marine Ecology: Reserve Networks Are Necessary, but Not Sufficient.

    Science.gov (United States)

    Almany, Glenn R

    2015-04-20

    New work reveals that the large network of no-take marine reserves on the Great Barrier Reef is working splendidly. However, bold, global action is needed to eliminate threats that reserves cannot guard against.

  1. Coupling ecological and social network models to assess "transmission" and "contagion" of an aquatic invasive species.

    Science.gov (United States)

    Haak, Danielle M; Fath, Brian D; Forbes, Valery E; Martin, Dustin R; Pope, Kevin L

    2017-04-01

    Network analysis is used to address diverse ecological, social, economic, and epidemiological questions, but few efforts have been made to combine these field-specific analyses into interdisciplinary approaches that effectively address how complex systems are interdependent and connected to one another. Identifying and understanding these cross-boundary connections improves natural resource management and promotes proactive, rather than reactive, decisions. This research had two main objectives; first, adapt the framework and approach of infectious disease network modeling so that it may be applied to the socio-ecological problem of spreading aquatic invasive species, and second, use this new coupled model to simulate the spread of the invasive Chinese mystery snail (Bellamya chinensis) in a reservoir network in Southeastern Nebraska, USA. The coupled model integrates an existing social network model of how anglers move on the landscape with new reservoir-specific ecological network models. This approach allowed us to identify 1) how angler movement among reservoirs aids in the spread of B. chinensis, 2) how B. chinensis alters energy flows within individual-reservoir food webs, and 3) a new method for assessing the spread of any number of non-native or invasive species within complex, social-ecological systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Effective local dynamic routing strategy for air route networks

    Institute of Scientific and Technical Information of China (English)

    Wu Wenjun; Zhao Lingxi

    2015-01-01

    With the rapid development of air transportation, network service ability has attracted a lot of attention in academe. Aiming to improve the throughput of the air route network (ARN), we propose an effective local dynamic routing strategy in this paper. Several factors, such as the rout-ing distance, the geographical distance and the real-time local traffic, are taken into consideration. When the ARN is in the normal free-flow state, the proposed strategy can recover the shortest path routing (SPR) strategy. When the ARN undergoes congestion, the proposed strategy changes the paths of flights based on the real-time local traffic information. The throughput of the Chinese air route network (CARN) is evaluated. Results confirm that the proposed strategy can significantly improve the throughput of CARN. Meanwhile, the increase in the average flying distance and time is tiny. Results also indicate the importance of the distance related factors in a routing strategy designed for the ARN.

  3. Qualia could arise from information processing in local cortical networks

    Directory of Open Access Journals (Sweden)

    Roger D Orpwood

    2013-03-01

    Full Text Available Re-entrant feedback, either within sensory cortex or arising from prefrontal areas, has been strongly linked to the emergence of consciousness, both in theoretical and experimental work. This idea, together with evidence for local micro-consciousness, suggests the generation of qualia could in some way result from local network activity under re-entrant activation. This paper explores the possibility by examining the processing of information by local cortical networks. It highlights the difference between the information structure (how the information is physically embodied, and the information message (what the information is about. It focuses on the network’s ability to recognise information structures amongst its inputs under conditions of extensive local feedback, and to then assign information messages to those structures. It is shown that if the re-entrant feedback enables the network to achieve an attractor state, then the message assigned in any given pass of information through the network is a representation of the message assigned in the previous pass-through of information. Based on this ability the paper argues that as information is repeatedly cycled through the network, the information message that is assigned evolves from a recognition of what the input structure is, to what it is like, to how it appears, to how it seems. It could enable individual networks to be the site of qualia generation. The paper goes on to show networks in cortical layers 2/3 and 5a have the connectivity required for the behaviour proposed, and reviews some evidence for a link between such local cortical cyclic activity and conscious percepts. It concludes with some predictions based on the theory discussed.

  4. Optical local area network emulations over Ethernet passive optical networks: A survey

    Institute of Scientific and Technical Information of China (English)

    PENG YunFeng; KUANG YuJun; LONG KePing

    2008-01-01

    As a promising solution to efficiently achieving fiber to the home (FTTH), Ethernet passive optical network (EPON) is currently improved to provide intercommunica-tion among customers, together with normal traffic delivery, via optical local area network emulation. It is a new research direction and expected to enhance the normal EPON performances. The purpose of this article is to review the state-of-the-art solutions to emulating optical local area networks (OLANs) over EPON. We discuss the major problems involved, e.g., network architecture, control mecha-nisms, and other potential enhancements. We also outline areas for future re-searches.

  5. Local area networks an introduction to the technology

    CERN Document Server

    McNamara, John E

    1985-01-01

    This concise book provides an objective introduction to local area networks - how they work, what they do, and how you can benefit from them. It outlines the pros and cons of the most common configurations so you can evaluate them in light of your own needs. You'll also learn about network software, with special emphasis on the ISO layered model of communications protocols.

  6. Correlation and network topologies in global and local stock indices

    Science.gov (United States)

    Nobi, Ashadun; Lee, Sungmin; Kim, Doo Hwan; Lee, Jae Woo

    2014-07-01

    We examined how the correlation and network structure of the global indices and local Korean indices have changed during years 2000-2012. The average correlations of the global indices increased with time, while the local indices showed a decreasing trend except for drastic changes during the crises. A significant change in the network topologies was observed due to the financial crises in both markets. The Jaccard similarities identified the change in the market state due to a crisis in both markets. The dynamic change of the Jaccard index can be used as an indicator of systemic risk or precursors of the crisis.

  7. Correlation and network topologies in global and local stock indices

    DEFF Research Database (Denmark)

    Nobi, A.; Lee, S.; Kim, D. H.;

    2014-01-01

    the crises. A significant change in the network topologies was observed due to the financial crises in both markets. The Jaccard similarities identified the change in the market state due to a crisis in both markets. The dynamic change of the Jaccard index can be used as an indicator of systemic risk......We examined how the correlation and network structure of the global indices and local Korean indices have changed during years 2000-2012. The average correlations of the global indices increased with time, while the local indices showed a decreasing trend except for drastic changes during...

  8. Traffic optimization in transport networks based on local routing

    Science.gov (United States)

    Scellato, S.; Fortuna, L.; Frasca, M.; Gómez-Gardeñes, J.; Latora, V.

    2010-01-01

    Congestion in transport networks is a topic of theoretical interest and practical importance. In this paper we study the flow of vehicles in urban street networks. In particular, we use a cellular automata model on a complex network to simulate the motion of vehicles along streets, coupled with a congestion-aware routing at street crossings. Such routing makes use of the knowledge of agents about traffic in nearby roads and allows the vehicles to dynamically update the routes towards their destinations. By implementing the model in real urban street patterns of various cities, we show that it is possible to achieve a global traffic optimization based on local agent decisions.

  9. Random matrix analysis of localization properties of gene coexpression network.

    Science.gov (United States)

    Jalan, Sarika; Solymosi, Norbert; Vattay, Gábor; Li, Baowen

    2010-04-01

    We analyze gene coexpression network under the random matrix theory framework. The nearest-neighbor spacing distribution of the adjacency matrix of this network follows Gaussian orthogonal statistics of random matrix theory (RMT). Spectral rigidity test follows random matrix prediction for a certain range and deviates afterwards. Eigenvector analysis of the network using inverse participation ratio suggests that the statistics of bulk of the eigenvalues of network is consistent with those of the real symmetric random matrix, whereas few eigenvalues are localized. Based on these IPR calculations, we can divide eigenvalues in three sets: (a) The nondegenerate part that follows RMT. (b) The nondegenerate part, at both ends and at intermediate eigenvalues, which deviates from RMT and expected to contain information about important nodes in the network. (c) The degenerate part with zero eigenvalue, which fluctuates around RMT-predicted value. We identify nodes corresponding to the dominant modes of the corresponding eigenvectors and analyze their structural properties.

  10. Estimating the Cumulative Ecological Effect of Local Scale Landscape Changes in South Florida

    Science.gov (United States)

    Hogan, Dianna M.; Labiosa, William; Pearlstine, Leonard; Hallac, David; Strong, David; Hearn, Paul; Bernknopf, Richard

    2012-01-01

    Ecosystem restoration in south Florida is a state and national priority centered on the Everglades wetlands. However, urban development pressures affect the restoration potential and remaining habitat functions of the natural undeveloped areas. Land use (LU) planning often focuses at the local level, but a better understanding of the cumulative effects of small projects at the landscape level is needed to support ecosystem restoration and preservation. The South Florida Ecosystem Portfolio Model (SFL EPM) is a regional LU planning tool developed to help stakeholders visualize LU scenario evaluation and improve communication about regional effects of LU decisions. One component of the SFL EPM is ecological value (EV), which is evaluated through modeled ecological criteria related to ecosystem services using metrics for (1) biodiversity potential, (2) threatened and endangered species, (3) rare and unique habitats, (4) landscape pattern and fragmentation, (5) water quality buffer potential, and (6) ecological restoration potential. In this article, we demonstrate the calculation of EV using two case studies: (1) assessing altered EV in the Biscayne Gateway area by comparing 2004 LU to potential LU in 2025 and 2050, and (2) the cumulative impact of adding limestone mines south of Miami. Our analyses spatially convey changing regional EV resulting from conversion of local natural and agricultural areas to urban, industrial, or extractive use. Different simulated local LU scenarios may result in different alterations in calculated regional EV. These case studies demonstrate methods that may facilitate evaluation of potential future LU patterns and incorporate EV into decision making.

  11. Self-organization of network dynamics into local quantized states.

    Science.gov (United States)

    Nicolaides, Christos; Juanes, Ruben; Cueto-Felgueroso, Luis

    2016-02-17

    Self-organization and pattern formation in network-organized systems emerges from the collective activation and interaction of many interconnected units. A striking feature of these non-equilibrium structures is that they are often localized and robust: only a small subset of the nodes, or cell assembly, is activated. Understanding the role of cell assemblies as basic functional units in neural networks and socio-technical systems emerges as a fundamental challenge in network theory. A key open question is how these elementary building blocks emerge, and how they operate, linking structure and function in complex networks. Here we show that a network analogue of the Swift-Hohenberg continuum model-a minimal-ingredients model of nodal activation and interaction within a complex network-is able to produce a complex suite of localized patterns. Hence, the spontaneous formation of robust operational cell assemblies in complex networks can be explained as the result of self-organization, even in the absence of synaptic reinforcements.

  12. Self-organization of network dynamics into local quantized states

    CERN Document Server

    Nicolaides, Christos; Cueto-Felgueroso, Luis

    2015-01-01

    Self-organization and pattern formation in network-organized systems emerges from the collective activation and interaction of many interconnected units. A striking feature of these non-equilibrium structures is that they are often localized and robust: only a small subset of the nodes, or cell assembly, is activated. Understanding the role of cell assemblies as basic functional units in neural networks and socio-technical systems emerges as a fundamental challenge in network theory. A key open question is how these elementary building blocks emerge, and how they operate, linking structure and function in complex networks. Here we show that a network analogue of the Swift-Hohenberg continuum model---a minimal-ingredients model of nodal activation and interaction within a complex network---is able to produce a complex suite of localized patterns. Hence, the spontaneous formation of robust operational cell assemblies in complex networks can be explained as the result of self-organization, even in the absence of...

  13. Fundamental Limits of Wideband Localization - Part II: Cooperative Networks

    CERN Document Server

    Shen, Yuan; Win, Moe Z

    2010-01-01

    The availability of positional information is of great importance in many commercial, governmental, and military applications. Localization is commonly accomplished through the use of radio communication between mobile devices (agents) and fixed infrastructure (anchors). However, precise determination of agent positions is a challenging task, especially in harsh environments due to radio blockage or limited anchor deployment. In these situations, cooperation among agents can significantly improve localization accuracy and reduce localization outage probabilities. A general framework of analyzing the fundamental limits of wideband localization has been developed in Part I of the paper. Here, we build on this framework and establish the fundamental limits of wideband cooperative location-aware networks. Our analysis is based on the waveforms received at the nodes, in conjunction with Fisher information inequality. We provide a geometrical interpretation of equivalent Fisher information for cooperative networks....

  14. Ecological Network Construction Based on Minimum Cumulative Resistance for the City of Nanjing, China

    Directory of Open Access Journals (Sweden)

    Jihong Dong

    2015-10-01

    Full Text Available With economic growth and the improvement of the urbanization level, human activities have constantly interfered with landscape patterns, resulting in serious threats to regional ecological security. Therefore, it is of great significance to study the evolution and optimization of the landscape patterns. Based on three TM images from 1990, 2000, and 2010, and selected landscape pattern indexes, the changes in the landscape pattern of Nanjing in the past twenty years were studied based on landscape ecology theory using Remote Sensing (RS and a Geographical Information System (GIS. The ecological network was built on the basis of extracted ecological nodes and the minimum cumulative resistance. The results show that changes in the landscape pattern of the city of Nanjing were notable. Class-level indexes indicate that the farmland landscape area decreased and the degree of patch fragmentation increased. The construction land area increased, and it tended to show dispersed distribution. The proportion of forest land increased and the shape of patches became more complex. The proportion of water firstly showed a decrease, followed by an increase, and the shape of the water became more regular. Landscape-level indexes indicate that biological diversity and the degree of fragmentation increased. Spatial heterogeneity of the natural landscape increased, and the patch shape of each landscape type developed similarly. The results also call for stepping-stones to enhance the connectivity and optimization of the ecological network, which will help improve ecological services and improve the landscape pattern of the city.

  15. Transboundary ecological networks as an adaptation strategy to climate change: The example of the Dutch - German border

    NARCIS (Netherlands)

    Rüter, S.; Vos, C.C.; Eupen, van M.; Rühmkorf, H.

    2014-01-01

    Establishing ecological networks across national boundaries is essential for species to adapt to shifts in future suitable climate zones. This paper presents a method to assess whether the existing ecological network in the Dutch – German border region is “climate proof”. Using distribution data and

  16. Strategic Ecological Network Competition in Emerging Markets: Theory and Case Analysis of A GPS Vehicle Navigation Firm

    Institute of Scientific and Technical Information of China (English)

    XIAO Lei; LI Shi-ming; ZHANG Jia-tong

    2006-01-01

    Using the case study methodology, firm's competition behavior in strategic network and strategic ecosystems are analyzed. With the ecology view, there is consistency between strategic network and strategic ecosystem. Enterprise should pursue for suitable ecological niche to hold a strategic competitive power.

  17. A Practical Localization Algorithm Based on Wireless Sensor Networks

    CERN Document Server

    Huang, Tao; Xia, Feng; Jin, Cheng; Li, Liang

    2010-01-01

    Many localization algorithms and systems have been developed by means of wireless sensor networks for both indoor and outdoor environments. To achieve higher localization accuracy, extra hardware equipments are utilized by most of the existing localization algorithms, which increase the cost and greatly limit the range of location-based applications. In this paper we present a method which can effectively meet different localization accuracy requirements of most indoor and outdoor location services in realistic applications. Our algorithm is composed of two phases: partition phase, in which the target region is split into small grids and localization refinement phase in which a higher accuracy location can be generated by applying a trick algorithm. A realistic demo system using our algorithm has been developed to illustrate its feasibility and availability. The results show that our algorithm can improve the localization accuracy.

  18. Mobile Anchor Assisted Node Localization for Wireless Sensor Networks

    CERN Document Server

    Chen, Hongyang; Huang, Pei; Poor, H Vincent; Sezaki, Kaoru

    2009-01-01

    In this paper, a cooperative localization algorithm is proposed that considers the existence of obstacles in mobilityassisted wireless sensor networks (WSNs). In this scheme, a mobile anchor (MA) node cooperates with static sensor nodes and moves actively to refine location performance. The localization accuracy of the proposed algorithm can be improved further by changing the transmission range of mobile anchor node. The algorithm takes advantage of cooperation betweenMAs and static sensors while, at the same time, taking into account the relay node availability to make the best use of beacon signals. For achieving high localization accuracy and coverage, a novel convex position estimation algorithm is proposed, which can effectively solve the localization problem when infeasible points occur because of the effects of radio irregularity and obstacles. This method is the only range-free based convex method to solve the localization problem when the feasible set of localization inequalities is empty. Simulatio...

  19. On-line learning algorithms for locally recurrent neural networks.

    Science.gov (United States)

    Campolucci, P; Uncini, A; Piazza, F; Rao, B D

    1999-01-01

    This paper focuses on on-line learning procedures for locally recurrent neural networks with emphasis on multilayer perceptron (MLP) with infinite impulse response (IIR) synapses and its variations which include generalized output and activation feedback multilayer networks (MLN's). We propose a new gradient-based procedure called recursive backpropagation (RBP) whose on-line version, causal recursive backpropagation (CRBP), presents some advantages with respect to the other on-line training methods. The new CRBP algorithm includes as particular cases backpropagation (BP), temporal backpropagation (TBP), backpropagation for sequences (BPS), Back-Tsoi algorithm among others, thereby providing a unifying view on gradient calculation techniques for recurrent networks with local feedback. The only learning method that has been proposed for locally recurrent networks with no architectural restriction is the one by Back and Tsoi. The proposed algorithm has better stability and higher speed of convergence with respect to the Back-Tsoi algorithm, which is supported by the theoretical development and confirmed by simulations. The computational complexity of the CRBP is comparable with that of the Back-Tsoi algorithm, e.g., less that a factor of 1.5 for usual architectures and parameter settings. The superior performance of the new algorithm, however, easily justifies this small increase in computational burden. In addition, the general paradigms of truncated BPTT and RTRL are applied to networks with local feedback and compared with the new CRBP method. The simulations show that CRBP exhibits similar performances and the detailed analysis of complexity reveals that CRBP is much simpler and easier to implement, e.g., CRBP is local in space and in time while RTRL is not local in space.

  20. Ecological Network Analysis for a Low-Carbon and High-Tech Industrial Park

    Directory of Open Access Journals (Sweden)

    Yi Lu

    2012-01-01

    Full Text Available Industrial sector is one of the indispensable contributors in global warming. Even if the occurrence of ecoindustrial parks (EIPs seems to be a good improvement in saving ecological crises, there is still a lack of definitional clarity and in-depth researches on low-carbon industrial parks. In order to reveal the processes of carbon metabolism in a low-carbon high-tech industrial park, we selected Beijing Development Area (BDA International Business Park in Beijing, China as case study, establishing a seven-compartment- model low-carbon metabolic network based on the methodology of Ecological Network Analysis (ENA. Integrating the Network Utility Analysis (NUA, Network Control Analysis (NCA, and system-wide indicators, we compartmentalized system sectors into ecological structure and analyzed dependence and control degree based on carbon metabolism. The results suggest that indirect flows reveal more mutuality and exploitation relation between system compartments and they are prone to positive sides for the stability of the whole system. The ecological structure develops well as an approximate pyramidal structure, and the carbon metabolism of BDA proves self-mutualistic and sustainable. Construction and waste management were found to be two active sectors impacting carbon metabolism, which was mainly regulated by internal and external environment.

  1. Ecological networks in river rehabilitation scenarios: Rhine-Econet; summary report

    NARCIS (Netherlands)

    Wolfert, H.P.; Harms, W.B.; Marteijn, E.C.L.; Reijnen, R.

    1996-01-01

    The significance of an ecological network of natural areas for a successful nature conservation and rehabilitation strategy of the Lower Rhine between Gorinchem (Netherlands) and Duisburg (Germany) is indicated. A scenario approach is used to illuminate variations in the planning of 10 000 ha of new

  2. Ecological network analysis for a low-carbon and high-tech industrial park.

    Science.gov (United States)

    Lu, Yi; Su, Meirong; Liu, Gengyuan; Chen, Bin; Zhou, Shiyi; Jiang, Meiming

    2012-01-01

    Industrial sector is one of the indispensable contributors in global warming. Even if the occurrence of ecoindustrial parks (EIPs) seems to be a good improvement in saving ecological crises, there is still a lack of definitional clarity and in-depth researches on low-carbon industrial parks. In order to reveal the processes of carbon metabolism in a low-carbon high-tech industrial park, we selected Beijing Development Area (BDA) International Business Park in Beijing, China as case study, establishing a seven-compartment- model low-carbon metabolic network based on the methodology of Ecological Network Analysis (ENA). Integrating the Network Utility Analysis (NUA), Network Control Analysis (NCA), and system-wide indicators, we compartmentalized system sectors into ecological structure and analyzed dependence and control degree based on carbon metabolism. The results suggest that indirect flows reveal more mutuality and exploitation relation between system compartments and they are prone to positive sides for the stability of the whole system. The ecological structure develops well as an approximate pyramidal structure, and the carbon metabolism of BDA proves self-mutualistic and sustainable. Construction and waste management were found to be two active sectors impacting carbon metabolism, which was mainly regulated by internal and external environment.

  3. A comprehensive multi-local-world model for complex networks

    Energy Technology Data Exchange (ETDEWEB)

    Fan Zhengping [Department of Automation, Sun Yat-sen University, Guangzhou 510275 (China); Chen Guanrong [Department of Electronic and Engineering, City University of Hong Kong, Hong Kong (China)], E-mail: eegchen@cityu.edu.hk; Zhang Yunong [Department of Automation, Sun Yat-sen University, Guangzhou 510275 (China)

    2009-04-20

    The nodes in a community within a network are much more connected to each other than to the others outside the community in the same network. This phenomenon has been commonly observed from many real-world networks, ranging from social to biological even to technical networks. Meanwhile, the number of communities in some real-world networks, such as the Internet and most social networks, are evolving with time. To model this kind of networks, the present Letter proposes a multi-local-world (MLW) model to capture and describe their essential topological properties. Based on the mean-field theory, the degree distribution of this model is obtained analytically, showing that the generated network has a novel topological feature as being not completely random nor completely scale-free but behaving somewhere between them. As a typical application, the MLW model is applied to characterize the Internet against some other models such as the BA, GBA, Fitness and HOT models, demonstrating the superiority of the new model.

  4. Comigrants and friends: informal networks and the transmission of traditional ecological knowledge among seminomadic pastoralists of Gujarat, India

    Directory of Open Access Journals (Sweden)

    Matthieu Salpeteur

    2016-06-01

    Full Text Available Previous research has shown that social organization may affect the distribution of traditional ecological knowledge (TEK within local communities of natural resource users in multiple ways. However, in this line of research the potential role of informal relationships has mostly been overlooked. In this article, we contribute toward filling this research gap by studying how two types of informal relationships, namely migration partnership and friendship, affect the distribution of TEK within a community of seminomadic pastoralists from the Kutch area, Gujarat, India. Using social network analysis, we map three networks, migration, men friendship, and women friendship, and compare with similarity-based quantitative approaches the clusters extracted from these networks in relation to four domains of TEK: knowledge about soils, about ethnoveterinary practices, about sheep breeds, and in ethnobotany. Our results show that (1 migration clusters are associated to significant variations in three TEK domains, while (2 friendship clusters are associated to minor variations. We relate these results to the importance of common practical experiences involved by joint migration. Moreover, kin relations are shown to strongly underlie friendship and migration relations, and as such appear as a potential driver of the dynamics of the local TEK system. We conclude by advocating for a better inclusion of such informal relationships in future research on local TEK dynamics, following recent developments in studies on natural resource governance.

  5. Probing many-body localization with neural networks

    Science.gov (United States)

    Schindler, Frank; Regnault, Nicolas; Neupert, Titus

    2017-06-01

    We show that a simple artificial neural network trained on entanglement spectra of individual states of a many-body quantum system can be used to determine the transition between a many-body localized and a thermalizing regime. Specifically, we study the Heisenberg spin-1/2 chain in a random external field. We employ a multilayer perceptron with a single hidden layer, which is trained on labeled entanglement spectra pertaining to the fully localized and fully thermal regimes. We then apply this network to classify spectra belonging to states in the transition region. For training, we use a cost function that contains, in addition to the usual error and regularization parts, a term that favors a confident classification of the transition region states. The resulting phase diagram is in good agreement with the one obtained by more conventional methods and can be computed for small systems. In particular, the neural network outperforms conventional methods in classifying individual eigenstates pertaining to a single disorder realization. It allows us to map out the structure of these eigenstates across the transition with spatial resolution. Furthermore, we analyze the network operation using the dreaming technique to show that the neural network correctly learns by itself the power-law structure of the entanglement spectra in the many-body localized regime.

  6. The Local Area Network (LAN) and Library Automation.

    Science.gov (United States)

    Farr, Rick C.

    1983-01-01

    Discussion of the use of inexpensive microcomputers in local area information networks (LAN) notes such minicomputer problems as costs, capacity, downtime, and vendor dependence, and the advantages of using LAN in offices and libraries, less costly LAN upgrades, library vendors and LAN systems, and LAN problems. A 28-item bibliography is provided.…

  7. Selecting a Local Area Network for an Academic Environment.

    Science.gov (United States)

    Aman, Mohammed M.; And Others

    1990-01-01

    Describes the process used to select a local area network (LAN) for the University of Wisconsin-Milwaukee School of Library and Information Science. The use of computers at the library school by staff, faculty, and students is described, technical aspects of a LAN are explained, and the future of LANs is discussed. (LRW)

  8. Applications of Local Area Networks of Microcomputers in Libraries.

    Science.gov (United States)

    Levert, Virginia M.

    1985-01-01

    Important features of local area networks (LAN) are reviewed, and several microcomputer LANs are described (ARCnet, Hinet, ShareNet, Ethernet, Omninet, PLAN 4000). Results of survey of 10 libraries using or planning to use a microcomputer LAN and considerations in choosing a LAN are reported. Forty-one references are cited. (EJS)

  9. Local Area Networks (LAN) in the Special Library.

    Science.gov (United States)

    Angier, Jennifer J.; Hoehl, Susan B.

    1986-01-01

    Presents a planning model for the automation of operations in a large hospital library and specifically describes the design and implementation of a local area network. Part 1 deals with the evolution of the idea, system planning, and design, and Part 2 addresses installation and implementation issues. (EM)

  10. The Educational Importance of Local Area Networks in Secondary Schools.

    Science.gov (United States)

    Shor, Richard

    1989-01-01

    Presents reasons for choosing a connected computer system for student use in secondary schools. The systems approach is discussed; two alternatives are compared, a central computer and a local area network (LAN) of microcomputers; software is described; and two scenarios of LAN use are presented. (four references) (LRW)

  11. Using a Local Area Network to Teach Computer Revision Skills.

    Science.gov (United States)

    Thompson, Diane P.

    1989-01-01

    Describes the use of a local area network and video switching equipment in teaching revision skills on computer. Explains that reading stories from texts, rewriting them from differing character viewpoints, and editing them as a group exposed students to a variety of writing problems and stimulated various revision strategies. (SG)

  12. An Experiment in Computer Conferencing Using a Local Area Network.

    Science.gov (United States)

    Baird, Patricia M.; Borer, Beatrice

    1987-01-01

    Describes various computer conferencing systems and discusses their effectiveness in terms of user acceptance and reactions to the technology. The methodology and findings of an experiment in which graduate students conducted a computer conference using a local area network and produced an electronic journal of the conference proceedings are…

  13. Local Area Network Implementation: Moving toward Phase III.

    Science.gov (United States)

    Hoehl, Susan B.

    1989-01-01

    Describes a LAN (local area network)-based automation project which has neared completion of the first phase of implementation at the Health Sciences Library of Allegheny General Hospital (Pittsburgh, PA). Changes in the library and its objectives with increased technological experience are examined. Diagrams of the current LAN configuration and…

  14. Bayesian Network Models for Local Dependence among Observable Outcome Variables

    Science.gov (United States)

    Almond, Russell G.; Mulder, Joris; Hemat, Lisa A.; Yan, Duanli

    2009-01-01

    Bayesian network models offer a large degree of flexibility for modeling dependence among observables (item outcome variables) from the same task, which may be dependent. This article explores four design patterns for modeling locally dependent observations: (a) no context--ignores dependence among observables; (b) compensatory context--introduces…

  15. Localization with Imprecise Distance Information in Sensor Networks

    NARCIS (Netherlands)

    Cao, M.; Anderson, B.D.O.; Morse, A.S.

    2005-01-01

    An approach to formulate geometric relations among distances between nodes as equality constraints is introduced in this paper to study the localization problem with imprecise distance information in sensor networks. These constraints can be further used to formulate optimization problems for distan

  16. Localization and Communication for UWB-based Wireless Sensor Networks

    NARCIS (Netherlands)

    Wang, Y.

    2011-01-01

    The great demand for location-aware wireless sensor networks (WSNs) motivates the research in this thesis. The unique characteristics of WSNs impose numerous challenges on localization and communication. In this thesis, we handle some key challenges and provide affordable solutions. Impulse radio u

  17. Study of space wireless local area network application

    Science.gov (United States)

    Zhang, Qingjun

    2005-11-01

    This paper describes the standards about wireless local area network (WLAN), and discusses the applications in formatting satellite and the types of WLAN, and give one type of WLAN conception which is Bus/Token-Ring. Finally, it describes some key technologies of the space WLAN.

  18. On Event Detection and Localization in Acyclic Flow Networks

    KAUST Repository

    Suresh, Mahima Agumbe

    2013-05-01

    Acyclic flow networks, present in many infrastructures of national importance (e.g., oil and gas and water distribution systems), have been attracting immense research interest. Existing solutions for detecting and locating attacks against these infrastructures have been proven costly and imprecise, particularly when dealing with large-scale distribution systems. In this article, to the best of our knowledge, for the first time, we investigate how mobile sensor networks can be used for optimal event detection and localization in acyclic flow networks. We propose the idea of using sensors that move along the edges of the network and detect events (i.e., attacks). To localize the events, sensors detect proximity to beacons, which are devices with known placement in the network. We formulate the problem of minimizing the cost of monitoring infrastructure (i.e., minimizing the number of sensors and beacons deployed) in a predetermined zone of interest, while ensuring a degree of coverage by sensors and a required accuracy in locating events using beacons. We propose algorithms for solving the aforementioned problem and demonstrate their effectiveness with results obtained from a realistic flow network simulator.

  19. Self-organization of network dynamics into local quantized states

    Science.gov (United States)

    Nicolaides, Christos; Juanes, Ruben; Cueto-Felgueroso, Luis

    2016-02-01

    Self-organization and pattern formation in network-organized systems emerges from the collective activation and interaction of many interconnected units. A striking feature of these non-equilibrium structures is that they are often localized and robust: only a small subset of the nodes, or cell assembly, is activated. Understanding the role of cell assemblies as basic functional units in neural networks and socio-technical systems emerges as a fundamental challenge in network theory. A key open question is how these elementary building blocks emerge, and how they operate, linking structure and function in complex networks. Here we show that a network analogue of the Swift-Hohenberg continuum model—a minimal-ingredients model of nodal activation and interaction within a complex network—is able to produce a complex suite of localized patterns. Hence, the spontaneous formation of robust operational cell assemblies in complex networks can be explained as the result of self-organization, even in the absence of synaptic reinforcements.

  20. What Determines Social Capital in a Social-Ecological System? Insights from a Network Perspective

    Science.gov (United States)

    Barnes-Mauthe, Michele; Gray, Steven Allen; Arita, Shawn; Lynham, John; Leung, PingSun

    2015-02-01

    Social capital is an important resource that can be mobilized for purposive action or competitive gain. The distribution of social capital in social-ecological systems can determine who is more productive at extracting ecological resources and who emerges as influential in guiding their management, thereby empowering some while disempowering others. Despite its importance, the factors that contribute to variation in social capital among individuals have not been widely studied. We adopt a network perspective to examine what determines social capital among individuals in social-ecological systems. We begin by identifying network measures of social capital relevant for individuals in this context, and review existing evidence concerning their determinants. Using a complete social network dataset from Hawaii's longline fishery, we employ social network analysis and other statistical methods to empirically estimate these measures and determine the extent to which individual stakeholder attributes explain variation within them. We find that ethnicity is the strongest predictor of social capital. Measures of human capital (i.e., education, experience), years living in the community, and information-sharing attitudes are also important. Surprisingly, we find that when controlling for other factors, industry leaders and formal fishery representatives are generally not well connected. Our results offer new quantitative insights on the relationship between stakeholder diversity, social networks, and social capital in a coupled social-ecological system, which can aid in identifying barriers and opportunities for action to overcome resource management problems. Our results also have implications for achieving resource governance that is not only ecologically and economically sustainable, but also equitable.

  1. What determines social capital in a social-ecological system? Insights from a network perspective.

    Science.gov (United States)

    Barnes-Mauthe, Michele; Gray, Steven Allen; Arita, Shawn; Lynham, John; Leung, PingSun

    2015-02-01

    Social capital is an important resource that can be mobilized for purposive action or competitive gain. The distribution of social capital in social-ecological systems can determine who is more productive at extracting ecological resources and who emerges as influential in guiding their management, thereby empowering some while disempowering others. Despite its importance, the factors that contribute to variation in social capital among individuals have not been widely studied. We adopt a network perspective to examine what determines social capital among individuals in social-ecological systems. We begin by identifying network measures of social capital relevant for individuals in this context, and review existing evidence concerning their determinants. Using a complete social network dataset from Hawaii's longline fishery, we employ social network analysis and other statistical methods to empirically estimate these measures and determine the extent to which individual stakeholder attributes explain variation within them. We find that ethnicity is the strongest predictor of social capital. Measures of human capital (i.e., education, experience), years living in the community, and information-sharing attitudes are also important. Surprisingly, we find that when controlling for other factors, industry leaders and formal fishery representatives are generally not well connected. Our results offer new quantitative insights on the relationship between stakeholder diversity, social networks, and social capital in a coupled social-ecological system, which can aid in identifying barriers and opportunities for action to overcome resource management problems. Our results also have implications for achieving resource governance that is not only ecologically and economically sustainable, but also equitable.

  2. A reverse localization scheme for underwater acoustic sensor networks.

    Science.gov (United States)

    Moradi, Marjan; Rezazadeh, Javad; Ismail, Abdul Samad

    2012-01-01

    Underwater Wireless Sensor Networks (UWSNs) provide new opportunities to observe and predict the behavior of aquatic environments. In some applications like target tracking or disaster prevention, sensed data is meaningless without location information. In this paper, we propose a novel 3D centralized, localization scheme for mobile underwater wireless sensor network, named Reverse Localization Scheme or RLS in short. RLS is an event-driven localization method triggered by detector sensors for launching localization process. RLS is suitable for surveillance applications that require very fast reactions to events and could report the location of the occurrence. In this method, mobile sensor nodes report the event toward the surface anchors as soon as they detect it. They do not require waiting to receive location information from anchors. Simulation results confirm that the proposed scheme improves the energy efficiency and reduces significantly localization response time with a proper level of accuracy in terms of mobility model of water currents. Major contributions of this method lie on reducing the numbers of message exchange for localization, saving the energy and decreasing the average localization response time.

  3. Agent Collaborative Target Localization and Classification in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sheng Wang

    2007-07-01

    Full Text Available Wireless sensor networks (WSNs are autonomous networks that have beenfrequently deployed to collaboratively perform target localization and classification tasks.Their autonomous and collaborative features resemble the characteristics of agents. Suchsimilarities inspire the development of heterogeneous agent architecture for WSN in thispaper. The proposed agent architecture views WSN as multi-agent systems and mobileagents are employed to reduce in-network communication. According to the architecture,an energy based acoustic localization algorithm is proposed. In localization, estimate oftarget location is obtained by steepest descent search. The search algorithm adapts tomeasurement environments by dynamically adjusting its termination condition. With theagent architecture, target classification is accomplished by distributed support vectormachine (SVM. Mobile agents are employed for feature extraction and distributed SVMlearning to reduce communication load. Desirable learning performance is guaranteed bycombining support vectors and convex hull vectors. Fusion algorithms are designed tomerge SVM classification decisions made from various modalities. Real world experimentswith MICAz sensor nodes are conducted for vehicle localization and classification.Experimental results show the proposed agent architecture remarkably facilitates WSNdesigns and algorithm implementation. The localization and classification algorithms alsoprove to be accurate and energy efficient.

  4. Functional Ecological Gene Networks to Reveal the Changes Among Microbial Interactions Under Elevated Carbon Dioxide Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Ye; Zhou, Jizhong; Luo, Feng; He, Zhili; Tu, Qichao; Zhi, Xiaoyang

    2010-05-17

    Biodiversity and its responses to environmental changes is a central issue in ecology, and for society. Almost all microbial biodiversity researches focus on species richness and abundance but ignore the interactions among different microbial species/populations. However, determining the interactions and their relationships to environmental changes in microbial communities is a grand challenge, primarily due to the lack of information on the network structure among different microbial species/populations. Here, a novel random matrix theory (RMT)-based conceptual framework for identifying functional ecological gene networks (fEGNs) is developed with the high throughput functional gene array hybridization data from the grassland microbial communities in a long-term FACE (Free Air CO2 Enrichment) experiment. Both fEGNs under elevated CO2 (eCO2) and ambient CO2 (aCO2) possessed general characteristics of many complex systems such as scale-free, small-world, modular and hierarchical. However, the topological structure of the fEGNs is distinctly different between eCO2 and aCO2, suggesting that eCO2 dramatically altered the interactions among different microbial functional groups/populations. In addition, the changes in network structure were significantly correlated with soil carbon and nitrogen dynamics, and plant productivity, indicating the potential importance of network interactions in ecosystem functioning. Elucidating network interactions in microbial communities and their responses to environmental changes are fundamentally important for research in microbial ecology, systems microbiology, and global change.

  5. Communities of minima in local optima networks of combinatorial spaces

    Science.gov (United States)

    Daolio, Fabio; Tomassini, Marco; Vérel, Sébastien; Ochoa, Gabriela

    2011-05-01

    In this work, we present a new methodology to study the structure of the configuration spaces of hard combinatorial problems. It consists in building the network that has as nodes the locally optimal configurations and as edges the weighted oriented transitions between their basins of attraction. We apply the approach to the detection of communities in the optima networks produced by two different classes of instances of a hard combinatorial optimization problem: the quadratic assignment problem (QAP). We provide evidence indicating that the two problem instance classes give rise to very different configuration spaces. For the so-called real-like class, the networks possess a clear modular structure, while the optima networks belonging to the class of random uniform instances are less well partitionable into clusters. This is convincingly supported by using several statistical tests. Finally, we briefly discuss the consequences of the findings for heuristically searching the corresponding problem spaces.

  6. Scalable Spectrum Sharing Mechanism for Local Area Networks Deployment

    DEFF Research Database (Denmark)

    Da Costa, Gustavo Wagner Oliveira; Cattoni, Andrea Fabio; Kovacs, Istvan Zsolt

    2010-01-01

    /dimensioning approach. Cognitive Radio (CR) based networking methodologies are considered as the most promising solutions for such radio resource sharing problems, enabling also unlicensed/open spectrum operations. In this paper we propose and evaluate a novel protocol stack for Link Layer (LL) and radio resource......The availability on the market of powerful and lightweight mobile devices has led to a fast diffusion of mobile services for end users and the trend is shifting from voice based services to multimedia contents distribution. The current access networks are, however, able to support relatively low...... in high mobility conditions. These goals can be only achieved through the use highly Optimized Local Area (OLA) access networks, operating at low range and low power transmissions. The efficient sharing of radio resources among OLAs will be very difficult to achieve with a traditional network planning...

  7. Changes of hierarchical network in local and world stock market

    Science.gov (United States)

    Patwary, Enayet Ullah; Lee, Jong Youl; Nobi, Ashadun; Kim, Doo Hwan; Lee, Jae Woo

    2017-10-01

    We consider the cross-correlation coefficients of the daily returns in the local and global stock markets. We generate the minimal spanning tree (MST) using the correlation matrix. We observe that the MSTs change their structure from chain-like networks to star-like networks during periods of market uncertainty. We quantify the measure of the hierarchical network utilizing the value of the hierarchy measured by the hierarchical path. The hierarchy and betweenness centrality characterize the state of the market regarding the impact of crises. During crises, the non-financial company is established as the central node of the MST. However, before the crisis and during stable periods, the financial company is occupying the central node of the MST in the Korean and the U.S. stock markets. The changes in the network structure and the central node are good indicators of an upcoming crisis.

  8. The predictive power of local properties of financial networks

    Science.gov (United States)

    Caraiani, Petre

    2017-01-01

    The literature on analyzing the dynamics of financial networks has focused so far on the predictive power of global measures of networks like entropy or index cohesive force. In this paper, I show that the local network properties have similar predictive power. I focus on key network measures like average path length, average degree or cluster coefficient, and also consider the diameter and the s-metric. Using Granger causality tests, I show that some of these measures have statistically significant prediction power with respect to the dynamics of aggregate stock market. Average path length is most robust relative to the frequency of data used or specification (index or growth rate). Most measures are found to have predictive power only for monthly frequency. Further evidences that support this view are provided through a simple regression model.

  9. A local algorithm for detecting community structures in dynamic networks

    CERN Document Server

    Massaro, Emanuele; Guazzini, Andrea; Passarella, Andrea; Bagnoli, Franco

    2013-01-01

    The emergence and the global adaptation of mobile devices has influenced human interactions at the individual, community, and social levels leading to the so called Cyber-Physical World (CPW) convergence scenario [1]. One of the most important features of CPW is the possibility of exploiting information about the structure of social communities of users, that manifest through joint movement patterns and frequency of physical co-location: mobile devices of users that belong to the same social community are likely to "see" each other (and thus be able to communicate through ad hoc networking techniques) more frequently and regularly than devices outside of the community. In mobile opportunistic networks, this fact can be exploited, for example, to optimize networking operations such as forwarding and dissemination of messages. In this paper we present a novel local cognitive-inspired algorithm for revealing the structure of these dynamic social networks by exploiting information about physical encounters, logge...

  10. The Google matrix controls the stability of structured ecological and biological networks

    Science.gov (United States)

    Stone, Lewi

    2016-09-01

    May's celebrated theoretical work of the 70's contradicted the established paradigm by demonstrating that complexity leads to instability in biological systems. Here May's random-matrix modelling approach is generalized to realistic large-scale webs of species interactions, be they structured by networks of competition, mutualism or both. Simple relationships are found to govern these otherwise intractable models, and control the parameter ranges for which biological systems are stable and feasible. Our analysis of model and real empirical networks is only achievable on introducing a simplifying Google-matrix reduction scheme, which in the process, yields a practical ecological eigenvalue stability index. These results provide an insight into how network topology, especially connectance, influences species stable coexistence. Constraints controlling feasibility (positive equilibrium populations) in these systems are found more restrictive than those controlling stability, helping explain the enigma of why many classes of feasible ecological models are nearly always stable.

  11. Enhanced Voting based Secure Localization for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    M. B. Nirmala

    2015-11-01

    Full Text Available Development of location estimation algorithms with improvement in location precision with lower cost, less energy consumption and less hardware support has become more important for many applications in Wireless Sensor Networks (WSNs. This paper addresses the problem of secure location determination, known as secure localization in WSNs using voting based technique which gives a search region in presence of anchor nodes. From the obtained search region trilateration is applied to know the position of sensor nodes. To avoid the involvement of sensor nodes in further location estimation process, bilateration is applied. Experimental analysis shows that the maximum number of nodes can be localized and accurate location of a node can be determined efficiently with low estimation error. To avoid the attacks and involvement of malicious nodes in the localization process, we implement an improved authentication and security algorithm. Using few location reference points in the localization process reduces the communication cost. The proposed scheme also provides very good localization accuracy.

  12. A Comparative Study of 11 Local Health Department Organizational Networks

    Science.gov (United States)

    Merrill, Jacqueline; Keeling, Jonathan W.; Carley, Kathleen M.

    2013-01-01

    Context Although the nation’s local health departments (LHDs) share a common mission, variability in administrative structures is a barrier to identifying common, optimal management strategies. There is a gap in understanding what unifying features LHDs share as organizations that could be leveraged systematically for achieving high performance. Objective To explore sources of commonality and variability in a range of LHDs by comparing intraorganizational networks. Intervention We used organizational network analysis to document relationships between employees, tasks, knowledge, and resources within LHDs, which may exist regardless of formal administrative structure. Setting A national sample of 11 LHDs from seven states that differed in size, geographic location, and governance. Participants Relational network data were collected via an on-line survey of all employees in 11 LHDs. A total of 1 062 out of 1 239 employees responded (84% response rate). Outcome Measures Network measurements were compared using coefficient of variation. Measurements were correlated with scores from the National Public Health Performance Assessment and with LHD demographics. Rankings of tasks, knowledge, and resources were correlated across pairs of LHDs. Results We found that 11 LHDs exhibited compound organizational structures in which centralized hierarchies were coupled with distributed networks at the point of service. Local health departments were distinguished from random networks by a pattern of high centralization and clustering. Network measurements were positively associated with performance for 3 of 10 essential services (r > 0.65). Patterns in the measurements suggest how LHDs adapt to the population served. Conclusions Shared network patterns across LHDs suggest where common organizational management strategies are feasible. This evidence supports national efforts to promote uniform standards for service delivery to diverse populations. PMID:20445462

  13. [Social network analysis of animal behavioral ecology: a cross-discipline approach].

    Science.gov (United States)

    Zhang, Peng

    2013-12-01

    Social network analysis (SNA) is a framework used to study the structure of societies. As an umbrella term that encompasses various tools of graph theory and mathematical models to visualize networks, SNA allows researchers to detect and quantify patterns in social networks. Within SNA, individuals are not independent, but are symbiotic or linked with one another in a network. Given its powerful analytical tools, SNA is capable of addressing a range of animal behaviors, and has accordingly become increasingly popular in behavioral ecology studies examining such notions as mate choice/sexual selection, cooperation, information flow and disease transition, behavioral strategies of individuals, fitness consequences of sociality and network stability. Nevertheless, SNA it relatively underutilized among Chinese behavioral ecologists. This study aims at highlighting the benefits of SNA in studying animal behaviors in order to promote greater utilization of SNA within Chinese studies. By first introducing social network theory and demonstrating how social networks can influence individual and collective behaviors, this paper provide a prospective overview of SNA's general utilization for the study of animal behavioral ecology as well as promising directions in the overall use of SNA.

  14. A simple model of bipartite cooperation for ecological and organizational networks.

    Science.gov (United States)

    Saavedra, Serguei; Reed-Tsochas, Felix; Uzzi, Brian

    2009-01-22

    In theoretical ecology, simple stochastic models that satisfy two basic conditions about the distribution of niche values and feeding ranges have proved successful in reproducing the overall structural properties of real food webs, using species richness and connectance as the only input parameters. Recently, more detailed models have incorporated higher levels of constraint in order to reproduce the actual links observed in real food webs. Here, building on previous stochastic models of consumer-resource interactions between species, we propose a highly parsimonious model that can reproduce the overall bipartite structure of cooperative partner-partner interactions, as exemplified by plant-animal mutualistic networks. Our stochastic model of bipartite cooperation uses simple specialization and interaction rules, and only requires three empirical input parameters. We test the bipartite cooperation model on ten large pollination data sets that have been compiled in the literature, and find that it successfully replicates the degree distribution, nestedness and modularity of the empirical networks. These properties are regarded as key to understanding cooperation in mutualistic networks. We also apply our model to an extensive data set of two classes of company engaged in joint production in the garment industry. Using the same metrics, we find that the network of manufacturer-contractor interactions exhibits similar structural patterns to plant-animal pollination networks. This surprising correspondence between ecological and organizational networks suggests that the simple rules of cooperation that generate bipartite networks may be generic, and could prove relevant in many different domains, ranging from biological systems to human society.

  15. Insights into the Ecology and Evolution of Polyploid Plants through Network Analysis.

    Science.gov (United States)

    Gallagher, Joseph P; Grover, Corrinne E; Hu, Guanjing; Wendel, Jonathan F

    2016-06-01

    Polyploidy is a widespread phenomenon throughout eukaryotes, with important ecological and evolutionary consequences. Although genes operate as components of complex pathways and networks, polyploid changes in genes and gene expression have typically been evaluated as either individual genes or as a part of broad-scale analyses. Network analysis has been fruitful in associating genomic and other 'omic'-based changes with phenotype for many systems. In polyploid species, network analysis has the potential not only to facilitate a better understanding of the complex 'omic' underpinnings of phenotypic and ecological traits common to polyploidy, but also to provide novel insight into the interaction among duplicated genes and genomes. This adds perspective to the global patterns of expression (and other 'omic') change that accompany polyploidy and to the patterns of recruitment and/or loss of genes following polyploidization. While network analysis in polyploid species faces challenges common to other analyses of duplicated genomes, present technologies combined with thoughtful experimental design provide a powerful system to explore polyploid evolution. Here, we demonstrate the utility and potential of network analysis to questions pertaining to polyploidy with an example involving evolution of the transgressively superior cotton fibres found in polyploid Gossypium hirsutum. By combining network analysis with prior knowledge, we provide further insights into the role of profilins in fibre domestication and exemplify the potential for network analysis in polyploid species. © 2016 John Wiley & Sons Ltd.

  16. Updating Road Networks by Local Renewal from GPS Trajectories

    Directory of Open Access Journals (Sweden)

    Tao Wu

    2016-09-01

    Full Text Available The long production cycle and huge cost of collecting road network data often leave the data lagging behind the latest real conditions. However, this situation is rapidly changing as the positioning techniques ubiquitously used in mobile devices are gradually being implemented in road network research and applications. Currently, the predominant approaches infer road networks from mobile location information (e.g., GPS trajectory data directly using various extracting algorithms, which leads to expensive consumption of computational resources in the case of large-scale areas. For this reason, we propose an alternative that renews road networks with a novel spiral strategy, including a hidden Markov model (HMM for detecting potential problems in existing road network data and a method to update the data, on the local scale, by generating new road segments from trajectory data. The proposed approach reduces computation costs on roads with completed or updated information by updating problem road segments in the minimum range of the road network. We evaluated the performance of our proposals using GPS traces collected from taxies and OpenStreetMap (OSM road networks covering urban areas of Wuhan City.

  17. EEG Resting-State Networks: microstates' source localization.

    Science.gov (United States)

    Custo, Anna; van der Ville, Dimitri; Wells, William M; Tomescu, Ioana M; Michel, Christoph

    2017-09-22

    Using EEG to elucidate the spontaneous activation of brain resting state networks is non trivial as the signal of interest is of low amplitude and it is difficult to distinguish the underlying neural sources. Using the principles of electric field topographical analysis, it is possible to estimate the meta-stable states of the brain (i.e., the resting state topographies, so-called microstates). We estimated seven resting state topographies explaining the EEG dataset with k-means clustering (N=164, 256 electrodes). Using a method specifically designed to localize the sources of broadband EEG scalp topographies by matching sensor and source space temporal patterns, we demonstrated that we can estimate the EEG resting state networks reliably by measuring the reproducibility of our findings. After subtracting their mean from the seven EEG resting state networks, we identified seven state-specific networks. The mean map includes regions known to be densely anatomically and functionally connected (superior frontal, superior parietal, insula, and anterior cingulate cortices). While the mean map can be interpreted as a "router", cross-linking multiple functional networks, the seven state-specific resting state networks partly resemble and extend previous fMRI-based networks estimated as the hemodynamic correlates of four canonical EEG microstates.

  18. A method for under-sampled ecological network data analysis: plant-pollination as case study

    Directory of Open Access Journals (Sweden)

    Peter B. Sorensen

    2012-01-01

    Full Text Available In this paper, we develop a method, termed the Interaction Distribution (ID method, for analysis of quantitative ecological network data. In many cases, quantitative network data sets are under-sampled, i.e. many interactions are poorly sampled or remain unobserved. Hence, the output of statistical analyses may fail to differentiate between patterns that are statistical artefacts and those which are real characteristics of ecological networks. The ID method can support assessment and inference of under-sampled ecological network data. In the current paper, we illustrate and discuss the ID method based on the properties of plant-animal pollination data sets of flower visitation frequencies. However, the ID method may be applied to other types of ecological networks. The method can supplement existing network analyses based on two definitions of the underlying probabilities for each combination of pollinator and plant species: (1, pi,j: the probability for a visit made by the i’th pollinator species to take place on the j’th plant species; (2, qi,j: the probability for a visit received by the j’th plant species to be made by the i’th pollinator. The method applies the Dirichlet distribution to estimate these two probabilities, based on a given empirical data set. The estimated mean values for pi,j and qi,j reflect the relative differences between recorded numbers of visits for different pollinator and plant species, and the estimated uncertainty of pi,j and qi,j decreases with higher numbers of recorded visits.

  19. Detecting impacts of extreme events with ecological in situ monitoring networks

    Directory of Open Access Journals (Sweden)

    M. D. Mahecha

    2017-09-01

    Full Text Available Extreme hydrometeorological conditions typically impact ecophysiological processes on land. Satellite-based observations of the terrestrial biosphere provide an important reference for detecting and describing the spatiotemporal development of such events. However, in-depth investigations of ecological processes during extreme events require additional in situ observations. The question is whether the density of existing ecological in situ networks is sufficient for analysing the impact of extreme events, and what are expected event detection rates of ecological in situ networks of a given size. To assess these issues, we build a baseline of extreme reductions in the fraction of absorbed photosynthetically active radiation (FAPAR, identified by a new event detection method tailored to identify extremes of regional relevance. We then investigate the event detection success rates of hypothetical networks of varying sizes. Our results show that large extremes can be reliably detected with relatively small networks, but also reveal a linear decay of detection probabilities towards smaller extreme events in log–log space. For instance, networks with  ≈  100 randomly placed sites in Europe yield a  ≥  90 % chance of detecting the eight largest (typically very large extreme events; but only a  ≥  50 % chance of capturing the 39 largest events. These findings are consistent with probability-theoretic considerations, but the slopes of the decay rates deviate due to temporal autocorrelation and the exact implementation of the extreme event detection algorithm. Using the examples of AmeriFlux and NEON, we then investigate to what degree ecological in situ networks can capture extreme events of a given size. Consistent with our theoretical considerations, we find that today's systematically designed networks (i.e. NEON reliably detect the largest extremes, but that the extreme event detection rates are not higher than would

  20. Globalization impacts on local commons: multiscale strategies for socioeconomic and ecological resilience

    Directory of Open Access Journals (Sweden)

    Timothy O. Randhir

    2016-02-01

    Full Text Available Globalization can have substantial impact on local commons byreducing sustainability of ecosystems and their vital services. Without effectivelocal institutions, these resources are at high risk of exploitation, especially tofeed global markets. This study proposes a multiscale ecosystem framework(MEF that incorporates information on ecosystem components, socioeconomicprocesses, and their interactions. This includes inter and intra commoninteractions and multi-scale processes to evaluate inter and intra scale changesin socioeconomic and ecological processes of commons. Local participationand multi-disciplinary information are critical in achieving sustainability. Usinga global dataset of selected indicators, a general decline is observable in localcommons that face globalization. The need for increasing resilience of commonsthrough multi-scale adaptation strategies can inform decisions at the national,state and local levels. Increased resilience through ecosystem-based approach canminimize impacts of globalization using information on multiattribute processes,equity considerations, development of robust institutions, and effective strategiesfor adaptation.

  1. Adaptive Local Information Transfer in Random Boolean Networks.

    Science.gov (United States)

    Haruna, Taichi

    2017-01-01

    Living systems such as gene regulatory networks and neuronal networks have been supposed to work close to dynamical criticality, where their information-processing ability is optimal at the whole-system level. We investigate how this global information-processing optimality is related to the local information transfer at each individual-unit level. In particular, we introduce an internal adjustment process of the local information transfer and examine whether the former can emerge from the latter. We propose an adaptive random Boolean network model in which each unit rewires its incoming arcs from other units to balance stability of its information processing based on the measurement of the local information transfer pattern. First, we show numerically that random Boolean networks can self-organize toward near dynamical criticality in our model. Second, the proposed model is analyzed by a mean-field theory. We recognize that the rewiring rule has a bootstrapping feature. The stationary indegree distribution is calculated semi-analytically and is shown to be close to dynamical criticality in a broad range of model parameter values.

  2. A robust localization algorithm in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    Xin LI; Bei HUA; Yi SHANG; Yan XIONG

    2008-01-01

    Most of the state-of-the-art localization algo-rithms in wireless sensor networks (WSNs) are vulnerable to various kinds of location attacks, whereas secure local-ization schemes proposed so far are too complex to apply to power constrained WSNs. This paper provides a distributed robust localization algorithm called Bilateration that employs a unified way to deal with all kinds of location attacks as well as other kinds of information distortion caused by node malfunction or abnormal environmental noise. Bilateration directly calculates two candidate posi-tions for every two heard anchors, and then uses the aver-age of a maximum set of close-by candidate positions as the location estimation. The basic idea behind Bilateration is that candidate positions calculated from reasonable (I.e.,error bounded) anchor positions and distance measure-ments tend to be close to each other, whereas candidate positions calculated from false anchor positions or distance measurements are highly unlikely to be close to each other if false information are not collaborated. By using ilateration instead of classical multilateration to compute location estimation, Bilateration requires much lower computa-tional complexity, yet still retains the same localization accuracy. This paper also evaluates and compares Bilateration with three multilateration-based localization algorithms, and the simulation results show that Bilateration achieves the best comprehensive performance and is more suitable to real wireless sensor networks.

  3. Internetworking satellite and local exchange networks for personal communications applications

    Science.gov (United States)

    Wolff, Richard S.; Pinck, Deborah

    1993-01-01

    The demand for personal communications services has shown unprecedented growth, and the next decade and beyond promise an era in which the needs for ubiquitous, transparent and personalized access to information will continue to expand in both scale and scope. The exchange of personalized information is growing from two-way voice to include data communications, electronic messaging and information services, image transfer, video, and interactive multimedia. The emergence of new land-based and satellite-based wireless networks illustrates the expanding scale and trend toward globalization and the need to establish new local exchange and exchange access services to meet the communications needs of people on the move. An important issue is to identify the roles that satellite networking can play in meeting these new communications needs. The unique capabilities of satellites, in providing coverage to large geographic areas, reaching widely dispersed users, for position location determination, and in offering broadcast and multicast services, can complement and extend the capabilities of terrestrial networks. As an initial step in exploring the opportunities afforded by the merger of satellite-based and land-based networks, several experiments utilizing the NASA ACTS satellite and the public switched local exchange network were undertaken to demonstrate the use of satellites in the delivery of personal communications services.

  4. Research on the Robustness of Interdependent Networks under Localized Attack

    Directory of Open Access Journals (Sweden)

    Junde Wang

    2017-06-01

    Full Text Available Critical infrastructures (CI are the cornerstone of modern society, and they are connected with each other through material, energy, or information. The robustness of interdependent CI systems under attack has been a hot topic in recent years, but previous studies mainly focused on malicious attacks or random failure. To analyze the impact of some natural disasters whose destructive force is mainly related to distance with respect to interdependent CI systems, we present a new localized attack mode considering destructive force decays with distance, and carry out simulations on several interdependent networks constructed by artificial and real world networks. Furthermore, this article analyzes the influence of coupling strength and coupling pattern on the robustness of interdependent system. The results show that dependency links between networks decrease the robustness of interdependence networks, but the robustness under failure probability degradation is not vulnerable like that under malicious attack or random failure. In addition, the coupling preference has little effect on the robustness of interdependent networks under the new localized attack strategy; when the average degree of subnetworks is large, the same conclusion can be obtained for the coupling strength.

  5. The role of social resource of indigenous people in local ecological resource management in China: A preliminary case in Zhangye, Northwestern China

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Social resources of indigenous people are valuable wealth, including the social norms, the relational network, belief, attitude as well as the social system which is accumulated from generation to generation. Those social resources are very important for local ecological resource management, which can help diffuseness and communion of skills and traditional conservation techniques for conserving and restoring the ecological sites. Social capital is one indicator of social resources, which is accepted widely. In order to investigate the role of social resources of indigenous people in local ecological resource management, the authors studied the relation between social capital of indigenous people and local ecological resource management, taking Zhangye City as an exam-ple. In this paper, social capital of indigenous people is quantified by constructing social capital index, composed of structural so-cial capital and cognitive social capital; local ecological resource management is quantified by constructing "Grain for Green Pro-ject" performance index. Based on correlation analysis approach and logistic regression analysis approach, the authors analyzed the relation between social capital and "Grain for Green Project" performance index, as well as the relations between "Grain for Green Project" performance index and other factors such as per capita net income, medical treatment and so on. Results showed that the correlation between social capital and "Grain for Green Project" performance index was positive, the coefficient was 0.761, with P<0.01. An increase of 1 unit in social capital is associated with an increase of 1.550 units in "Grain for Green Project" per-formance. With factor, such as faction, per capita net income, medical treatment, increasing 1 unit, the "Grain for Green Project" performance index will increase 3.912, 1.039 and 1.005 units, respectively.

  6. Localized Algorithm for Channel Assignment in Cognitive Radio Networks

    Directory of Open Access Journals (Sweden)

    Harpreet Kaur

    2015-12-01

    Full Text Available Cognitive Radio has been emerged as a revolutionary solution to migrate the current shortage of spectrum allocation in wireless networks. In this paper, an improved localized channel allocation algorithm based on channel weight is proposed. A factor of channel stability is introduced based on link environment, which efficiently assigns the best channels to the links. Based on the framework, a conflict resolution strategy is used to make the scheme adaptable to different network conditions. Calculations indicate that this algorithm can reduce the conflicts, increase the delivery rate and link assignment rate compared with the basic channel assignment algorithm.

  7. Using ecological null models to assess the potential for marine protected area networks to protect biodiversity.

    Science.gov (United States)

    Semmens, Brice X; Auster, Peter J; Paddack, Michelle J

    2010-01-27

    Marine protected area (MPA) networks have been proposed as a principal method for conserving biological diversity, yet patterns of diversity may ultimately complicate or compromise the development of such networks. We show how a series of ecological null models can be applied to assemblage data across sites in order to identify non-random biological patterns likely to influence the effectiveness of MPA network design. We use fish census data from Caribbean fore-reefs as a test system and demonstrate that: 1) site assemblages were nested, such that species found on sites with relatively few species were subsets of those found on sites with relatively many species, 2) species co-occurred across sites more than expected by chance once species-habitat associations were accounted for, and 3) guilds were most evenly represented at the richest sites and richness among all guilds was correlated (i.e., species and trophic diversity were closely linked). These results suggest that the emerging Caribbean marine protected area network will likely be successful at protecting regional diversity even if planning is largely constrained by insular, inventory-based design efforts. By recasting ecological null models as tests of assemblage patterns likely to influence management action, we demonstrate how these classic tools of ecological theory can be brought to bear in applied conservation problems.

  8. Using ecological null models to assess the potential for marine protected area networks to protect biodiversity.

    Directory of Open Access Journals (Sweden)

    Brice X Semmens

    Full Text Available Marine protected area (MPA networks have been proposed as a principal method for conserving biological diversity, yet patterns of diversity may ultimately complicate or compromise the development of such networks. We show how a series of ecological null models can be applied to assemblage data across sites in order to identify non-random biological patterns likely to influence the effectiveness of MPA network design. We use fish census data from Caribbean fore-reefs as a test system and demonstrate that: 1 site assemblages were nested, such that species found on sites with relatively few species were subsets of those found on sites with relatively many species, 2 species co-occurred across sites more than expected by chance once species-habitat associations were accounted for, and 3 guilds were most evenly represented at the richest sites and richness among all guilds was correlated (i.e., species and trophic diversity were closely linked. These results suggest that the emerging Caribbean marine protected area network will likely be successful at protecting regional diversity even if planning is largely constrained by insular, inventory-based design efforts. By recasting ecological null models as tests of assemblage patterns likely to influence management action, we demonstrate how these classic tools of ecological theory can be brought to bear in applied conservation problems.

  9. Motivating conservation: Learning to care for other species in a local ecological community

    Science.gov (United States)

    Laflamme, Michael

    Large-scale, sustainable biodiversity conservation must motivate action by local communities. I united theories and practices in biology and psychology to study the process by which people are motivated to care for other species, and to what extent caring results in helping. Participants (N = 1200), age 8--22, interacted with native fish and aquatic insects in their habitats during 21 field experiences through Lake County, Montana educational institutions. Native fish were chosen because they are familiar to local people, yet different from people in their morphology, biomechanics, and habitat. In Phase I, two activity models for conservation emerged: the Habitat approach linked concepts in ecology, reciprocation, and a moral orientation toward justice, while the Behavior approach linked concepts in behavior, kin selection, and a moral orientation toward caring. These two approaches were compared in Phase II through seven sets of experiences that varied only in point of view: toward the habitat or toward behavior. I found that through sustained contact between people and local fish in their habitats, in the field and in cold-water aquaria, people empathized with fish more than with habitats. They perceived fish states by interpreting their behavior, and created meaning by focusing on fish social interactions with their habitat, with other fish, and with people. They used the information gained from empathy to identify ongoing conservation needs and to design conservation plans. Attention to behavior increased perception of human impacts on fish; perception of relatedness with fish; similarity with the physiology, behavior, minds and lives of fish; desire for non-material benefits in return for helping fish; and cohesion within participant groups. These perceptions varied with age and gender. For example, women and children emphasized values of non-material returns for time invested. This study recommends a behavioral-ecology approach for motivating conservation and

  10. Long-term oil contamination alters the molecular ecological networks of soil microbial functional genes

    Directory of Open Access Journals (Sweden)

    Yuting eLiang

    2016-02-01

    Full Text Available With knowledge on microbial composition and diversity, investigation of within-community interactions is a further step to elucidate microbial ecological functions, such as the biodegradation of hazardous contaminants. In this work, microbial functional molecular ecological networks were studied in both contaminated and uncontaminated soils to determine the possible influences of oil contamination on microbial interactions and potential functions. Soil samples were obtained from an oil-exploring site located in South China, and the microbial functional genes were analyzed with GeoChip, a high-throughput functional microarray. By building random networks based on null model, we demonstrated that overall network structures and properties were significantly different between contaminated and uncontaminated soils (P < 0.001. Network connectivity, module numbers, and modularity were all reduced with contamination. Moreover, the topological roles of the genes (module hub and connectors were altered with oil contamination. Subnetworks of genes involved in alkane and polycyclic aromatic hydrocarbon degradation were also constructed. Negative co-occurrence patterns prevailed among functional genes, thereby indicating probable competition relationships. The potential keystone genes, defined as either hubs or genes with highest connectivities in the network, were further identified. The network constructed in this study predicted the potential effects of anthropogenic contamination on microbial community co-occurrence interactions.

  11. LaRC local area networks to support distributed computing

    Science.gov (United States)

    Riddle, E. P.

    1984-01-01

    The Langley Research Center's (LaRC) Local Area Network (LAN) effort is discussed. LaRC initiated the development of a LAN to support a growing distributed computing environment at the Center. The purpose of the network is to provide an improved capability (over inteactive and RJE terminal access) for sharing multivendor computer resources. Specifically, the network will provide a data highway for the transfer of files between mainframe computers, minicomputers, work stations, and personal computers. An important influence on the overall network design was the vital need of LaRC researchers to efficiently utilize the large CDC mainframe computers in the central scientific computing facility. Although there was a steady migration from a centralized to a distributed computing environment at LaRC in recent years, the work load on the central resources increased. Major emphasis in the network design was on communication with the central resources within the distributed environment. The network to be implemented will allow researchers to utilize the central resources, distributed minicomputers, work stations, and personal computers to obtain the proper level of computing power to efficiently perform their jobs.

  12. Local authorities facing flood related networks failures in France

    Directory of Open Access Journals (Sweden)

    Gallet Violette

    2016-01-01

    Full Text Available Network critical infrastructures have become vital to keep our societies running in every-day situations, but also during crisis and recovery. Involving many stakeholders at different scales, they form a complex system that can be easily disturbed by internal or external events, because then all the dependencies that allow to optimizing their working become flaws that help failures to spread beyond the flooded area and from one network to another. Thus every flood reminds us how vulnerable infrastructures are and how much it costs when they fail. But whereas it isn’t so difficult to adapt new urban development, what about all the existing and exposed infrastructures? CEPRI carried out research on encountered difficulties and good practices to understand the situation and consider improvement opportunities. We worked out three steps to a better territory resilience to flood. First, get a better knowledge of networks. Then, as far as possible, reduce networks vulnerability. Finally, as risks of network failures always remain, get prepared to cope with disruptions! CEPRI gathered many experiences to illustrate and strengthen its work, which aims at helping local authorities to reduce their vulnerability to flood and related networks failures.

  13. Localization with a Mobile Beacon in Underwater Acoustic Sensor Networks

    Directory of Open Access Journals (Sweden)

    Sangho Lee

    2012-04-01

    Full Text Available Localization is one of the most important issues associated with underwater acoustic sensor networks, especially when sensor nodes are randomly deployed. Given that it is difficult to deploy beacon nodes at predetermined locations, localization schemes with a mobile beacon on the sea surface or along the planned path are inherently convenient, accurate, and energy-efficient. In this paper, we propose a new range-free Localization with a Mobile Beacon (LoMoB. The mobile beacon periodically broadcasts a beacon message containing its location. Sensor nodes are individually localized by passively receiving the beacon messages without inter-node communications. For location estimation, a set of potential locations are obtained as candidates for a node’s location and then the node’s location is determined through the weighted mean of all the potential locations with the weights computed based on residuals.

  14. Localization with a mobile beacon in underwater acoustic sensor networks.

    Science.gov (United States)

    Lee, Sangho; Kim, Kiseon

    2012-01-01

    Localization is one of the most important issues associated with underwater acoustic sensor networks, especially when sensor nodes are randomly deployed. Given that it is difficult to deploy beacon nodes at predetermined locations, localization schemes with a mobile beacon on the sea surface or along the planned path are inherently convenient, accurate, and energy-efficient. In this paper, we propose a new range-free Localization with a Mobile Beacon (LoMoB). The mobile beacon periodically broadcasts a beacon message containing its location. Sensor nodes are individually localized by passively receiving the beacon messages without inter-node communications. For location estimation, a set of potential locations are obtained as candidates for a node's location and then the node's location is determined through the weighted mean of all the potential locations with the weights computed based on residuals.

  15. Wlan-Based Indoor Localization Using Neural Networks

    Science.gov (United States)

    Saleem, Fasiha; Wyne, Shurjeel

    2016-07-01

    Wireless indoor localization has generated recent research interest due to its numerous applications. This work investigates Wi-Fi based indoor localization using two variants of the fingerprinting approach. Specifically, we study the application of an artificial neural network (ANN) for implementing the fingerprinting approach and compare its localization performance with a probabilistic fingerprinting method that is based on maximum likelihood estimation (MLE) of the user location. We incorporate spatial correlation of fading into our investigations, which is often neglected in simulation studies and leads to erroneous location estimates. The localization performance is quantified in terms of accuracy, precision, robustness, and complexity. Multiple methods for handling the case of missing APs in online stage are investigated. Our results indicate that ANN-based fingerprinting outperforms the probabilistic approach for all performance metrics considered in this work.

  16. Real time network traffic monitoring for wireless local area networks based on compressed sensing

    Science.gov (United States)

    Balouchestani, Mohammadreza

    2017-05-01

    A wireless local area network (WLAN) is an important type of wireless networks which connotes different wireless nodes in a local area network. WLANs suffer from important problems such as network load balancing, large amount of energy, and load of sampling. This paper presents a new networking traffic approach based on Compressed Sensing (CS) for improving the quality of WLANs. The proposed architecture allows reducing Data Delay Probability (DDP) to 15%, which is a good record for WLANs. The proposed architecture is increased Data Throughput (DT) to 22 % and Signal to Noise (S/N) ratio to 17 %, which provide a good background for establishing high qualified local area networks. This architecture enables continuous data acquisition and compression of WLAN's signals that are suitable for a variety of other wireless networking applications. At the transmitter side of each wireless node, an analog-CS framework is applied at the sensing step before analog to digital converter in order to generate the compressed version of the input signal. At the receiver side of wireless node, a reconstruction algorithm is applied in order to reconstruct the original signals from the compressed signals with high probability and enough accuracy. The proposed algorithm out-performs existing algorithms by achieving a good level of Quality of Service (QoS). This ability allows reducing 15 % of Bit Error Rate (BER) at each wireless node.

  17. Fault Localization Analysis Based on Deep Neural Network

    Directory of Open Access Journals (Sweden)

    Wei Zheng

    2016-01-01

    Full Text Available With software’s increasing scale and complexity, software failure is inevitable. To date, although many kinds of software fault localization methods have been proposed and have had respective achievements, they also have limitations. In particular, for fault localization techniques based on machine learning, the models available in literatures are all shallow architecture algorithms. Having shortcomings like the restricted ability to express complex functions under limited amount of sample data and restricted generalization ability for intricate problems, the faults cannot be analyzed accurately via those methods. To that end, we propose a fault localization method based on deep neural network (DNN. This approach is capable of achieving the complex function approximation and attaining distributed representation for input data by learning a deep nonlinear network structure. It also shows a strong capability of learning representation from a small sized training dataset. Our DNN-based model is trained utilizing the coverage data and the results of test cases as input and we further locate the faults by testing the trained model using the virtual test suite. This paper conducts experiments on the Siemens suite and Space program. The results demonstrate that our DNN-based fault localization technique outperforms other fault localization methods like BPNN, Tarantula, and so forth.

  18. INTERPLANETARY NETWORK LOCALIZATIONS OF KONUS SHORT GAMMA-RAY BURSTS

    Energy Technology Data Exchange (ETDEWEB)

    Pal' shin, V. D.; Svinkin, D. S.; Aptekar, R. L.; Golenetskii, S. V.; Frederiks, D. D.; Mazets, E. P.; Oleynik, P. P.; Ulanov, M. V. [Ioffe Physical Technical Institute, St. Petersburg, 194021 (Russian Federation); Hurley, K. [Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720-7450 (United States); Cline, T.; Trombka, J.; McClanahan, T. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Mitrofanov, I. G.; Golovin, D. V.; Kozyrev, A. S.; Litvak, M. L.; Sanin, A. B. [Space Research Institute, 84/32, Profsoyuznaya, Moscow 117997 (Russian Federation); Boynton, W.; Fellows, C.; Harshman, K., E-mail: val@mail.ioffe.ru [Department of Planetary Sciences, University of Arizona, Tucson, AZ 85721 (United States); and others

    2013-08-15

    Between the launch of the Global Geospace Science Wind spacecraft in 1994 November and the end of 2010, the Konus-Wind experiment detected 296 short-duration gamma-ray bursts (including 23 bursts which can be classified as short bursts with extended emission). During this period, the Interplanetary Network (IPN) consisted of up to 11 spacecraft, and using triangulation, the localizations of 271 bursts were obtained. We present the most comprehensive IPN localization data on these events. The short burst detection rate, {approx}18 yr{sup -1}, exceeds that of many individual experiments.

  19. Net Locality Why Location Matters in a Networked World

    CERN Document Server

    Gordon, Eric

    2011-01-01

    The first book to provide an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps, to location-based social networks and games, such as Foursquare and facebook.Warns of the threats these technologies, such as data surveillance, present to our sense of privacy, while also outlining the opportunities for pro-social developments.Provides a theory of the web in the context

  20. Multiplex networks in metropolitan areas: generic features and local effects

    CERN Document Server

    Strano, Emanuele; Dobson, Simon; Barthelemy, Marc

    2015-01-01

    Most large cities are spanned by more than one transportation system. These different modes of transport have usually been studied separately: it is however important to understand the impact on urban systems of the coupling between them and we report in this paper an empirical analysis of the coupling between the street network and the subway for the two large metropolitan areas of London and New York. We observe a similar behaviour for network quantities related to quickest paths suggesting the existence of generic mechanisms operating beyond the local peculiarities of the specific cities studied. An analysis of the betweenness centrality distribution shows that the introduction of underground networks operate as a decentralising force creating congestions in places located at the end of underground lines. Also, we find that increasing the speed of subways is not always beneficial and may lead to unwanted uneven spatial distributions of accessibility. In fact, for London -- but not for New York -- there is ...

  1. Local clustering in scale-free networks with hidden variables.

    Science.gov (United States)

    van der Hofstad, Remco; Janssen, A J E M; van Leeuwaarden, Johan S H; Stegehuis, Clara

    2017-02-01

    We investigate the presence of triangles in a class of correlated random graphs in which hidden variables determine the pairwise connections between vertices. The class rules out self-loops and multiple edges. We focus on the regime where the hidden variables follow a power law with exponent τ∈(2,3), so that the degrees have infinite variance. The natural cutoff h_{c} characterizes the largest degrees in the hidden variable models, and a structural cutoff h_{s} introduces negative degree correlations (disassortative mixing) due to the infinite-variance degrees. We show that local clustering decreases with the hidden variable (or degree). We also determine how the average clustering coefficient C scales with the network size N, as a function of h_{s} and h_{c}. For scale-free networks with exponent 2vanish only for networks as large as N=10^{9}.

  2. Experimental violation of local causality in a quantum network

    Science.gov (United States)

    Carvacho, Gonzalo; Andreoli, Francesco; Santodonato, Luca; Bentivegna, Marco; Chaves, Rafael; Sciarrino, Fabio

    2017-03-01

    Bell's theorem plays a crucial role in quantum information processing and thus several experimental investigations of Bell inequalities violations have been carried out over the years. Despite their fundamental relevance, however, previous experiments did not consider an ingredient of relevance for quantum networks: the fact that correlations between distant parties are mediated by several, typically independent sources. Here, using a photonic setup, we investigate a quantum network consisting of three spatially separated nodes whose correlations are mediated by two distinct sources. This scenario allows for the emergence of the so-called non-bilocal correlations, incompatible with any local model involving two independent hidden variables. We experimentally witness the emergence of this kind of quantum correlations by violating a Bell-like inequality under the fair-sampling assumption. Our results provide a proof-of-principle experiment of generalizations of Bell's theorem for networks, which could represent a potential resource for quantum communication protocols.

  3. A Unifying Framework for Local Throughput in Wireless Networks

    CERN Document Server

    Pinto, Pedro C

    2010-01-01

    With the increased competition for the electromagnetic spectrum, it is important to characterize the impact of interference in the performance of a wireless network, which is traditionally measured by its throughput. This paper presents a unifying framework for characterizing the local throughput in wireless networks. We first analyze the throughput of a probe link from a connectivity perspective, in which a packet is successfully received if it does not collide with other packets from nodes within its reach (called the audible interferers). We then characterize the throughput from a signal-to-interference-plus-noise ratio (SINR) perspective, in which a packet is successfully received if the SINR exceeds some threshold, considering the interference from all emitting nodes in the network. Our main contribution is to generalize and unify various results scattered throughout the literature. In particular, the proposed framework encompasses arbitrary wireless propagation effects (e.g, Nakagami-m fading, Rician fa...

  4. Experimental violation of local causality in a quantum network.

    Science.gov (United States)

    Carvacho, Gonzalo; Andreoli, Francesco; Santodonato, Luca; Bentivegna, Marco; Chaves, Rafael; Sciarrino, Fabio

    2017-03-16

    Bell's theorem plays a crucial role in quantum information processing and thus several experimental investigations of Bell inequalities violations have been carried out over the years. Despite their fundamental relevance, however, previous experiments did not consider an ingredient of relevance for quantum networks: the fact that correlations between distant parties are mediated by several, typically independent sources. Here, using a photonic setup, we investigate a quantum network consisting of three spatially separated nodes whose correlations are mediated by two distinct sources. This scenario allows for the emergence of the so-called non-bilocal correlations, incompatible with any local model involving two independent hidden variables. We experimentally witness the emergence of this kind of quantum correlations by violating a Bell-like inequality under the fair-sampling assumption. Our results provide a proof-of-principle experiment of generalizations of Bell's theorem for networks, which could represent a potential resource for quantum communication protocols.

  5. Developing a Micropayments System in Local Area Networks

    Directory of Open Access Journals (Sweden)

    Cristian GEORGESCU

    2011-11-01

    Full Text Available Starting from the solution of aggregating micropayments in a local area network that operates with reduced costs, with simple and easy to use equipments, with security procedures that are not so complicated, based on the rapport between the cost of fraud and the expected value obtained through fraud, a first stage of developing this system has been accomplished and materialized in the analysis stage by using some of the diagrams put to use by UML.

  6. Program For Local-Area-Network Electronic Mail

    Science.gov (United States)

    Weiner, Michael J.

    1989-01-01

    MailRoom is computer program for local-area network (LAN) electronic mail. Enables users of LAN to exchange electronically notes, letters, reminders, or any sort of communication via their computers. Links all users of LAN into communication circle in which messages created, sent, copied, printed, downloaded, uploaded, and deleted through series of menu-driven screens. Includes feature that enables users to determine whether messages sent have been read by receivers. Written in Microsoft QuickBasic.

  7. Functional brain networks develop from a "local to distributed" organization.

    Directory of Open Access Journals (Sweden)

    Damien A Fair

    2009-05-01

    Full Text Available The mature human brain is organized into a collection of specialized functional networks that flexibly interact to support various cognitive functions. Studies of development often attempt to identify the organizing principles that guide the maturation of these functional networks. In this report, we combine resting state functional connectivity MRI (rs-fcMRI, graph analysis, community detection, and spring-embedding visualization techniques to analyze four separate networks defined in earlier studies. As we have previously reported, we find, across development, a trend toward 'segregation' (a general decrease in correlation strength between regions close in anatomical space and 'integration' (an increased correlation strength between selected regions distant in space. The generalization of these earlier trends across multiple networks suggests that this is a general developmental principle for changes in functional connectivity that would extend to large-scale graph theoretic analyses of large-scale brain networks. Communities in children are predominantly arranged by anatomical proximity, while communities in adults predominantly reflect functional relationships, as defined from adult fMRI studies. In sum, over development, the organization of multiple functional networks shifts from a local anatomical emphasis in children to a more "distributed" architecture in young adults. We argue that this "local to distributed" developmental characterization has important implications for understanding the development of neural systems underlying cognition. Further, graph metrics (e.g., clustering coefficients and average path lengths are similar in child and adult graphs, with both showing "small-world"-like properties, while community detection by modularity optimization reveals stable communities within the graphs that are clearly different between young children and young adults. These observations suggest that early school age children and adults

  8. Local area networking in a radio quiet environment

    Science.gov (United States)

    Childers, Edwin L.; Hunt, Gareth; Brandt, Joseph J.

    2002-11-01

    The Green Bank facility of the National Radio Astronomy Observatory is spread out over 2,700 acres in the Allegheny Mountains of West Virginia. Good communication has always been needed between the radio telescopes and the control buildings. The National Radio Quiet Zone helps protect the Green Bank site from radio transmissions that interfere with the astronomical signals. Due to stringent Radio Frequency Interference (RFI) requirements, a fiber optic communication system was used for Ethernet transmissions on the site and coaxial cable within the buildings. With the need for higher speed communications, the entire network has been upgraded to use optical fiber with modern Ethernet switches. As with most modern equipment, the implementation of the control of the newly deployed Green Bank Telescope (GBT) depends heavily on TCP/IP. In order to protect the GBT from the commodity Internet, the GBT uses a non-routable network. Communication between the control building Local Area Network (LAN) and the GBT is implemented using a Virtual LAN (VLAN). This configuration will be extended to achieve isolation between trusted local user systems, the GBT, and other Internet users. Legitimate access to the site, for example by remote observers, is likely to be implemented using a virtual private network (VPN).

  9. A 1:1000 scale model of the digital world: Global connectivity can lead to the extinction of local networks

    CERN Document Server

    Kleineberg, Kaj-Kolja

    2015-01-01

    The overwhelming success of online social networks, the key actors in the cosmos of the Web 2.0, has reshaped human interactions on a worldwide scale. To understand the fundamental mechanisms which determine the fate of online social networks at the system level, we recently introduced a general ecological theory of the digital world. In this paper, we discuss the impact of heterogeneity in the network intrinsic fitness and present how the general theory can be applied to understand the competition between an international network, like Facebook, and local services. To this end, we construct a 1:1000 scale model of the digital world enclosing the 80 countries with most Internet users. We find that above a certain threshold the level of global connectivity can lead to the extinction of local networks. In addition, we reveal the complex role the tendency of individuals to engage in more active networks plays for the probability of local networks to become extinct and provide insights into the conditions under w...

  10. Reputation-Based Secure Sensor Localization in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Jingsha He

    2014-01-01

    Full Text Available Location information of sensor nodes in wireless sensor networks (WSNs is very important, for it makes information that is collected and reported by the sensor nodes spatially meaningful for applications. Since most current sensor localization schemes rely on location information that is provided by beacon nodes for the regular sensor nodes to locate themselves, the accuracy of localization depends on the accuracy of location information from the beacon nodes. Therefore, the security and reliability of the beacon nodes become critical in the localization of regular sensor nodes. In this paper, we propose a reputation-based security scheme for sensor localization to improve the security and the accuracy of sensor localization in hostile or untrusted environments. In our proposed scheme, the reputation of each beacon node is evaluated based on a reputation evaluation model so that regular sensor nodes can get credible location information from highly reputable beacon nodes to accomplish localization. We also perform a set of simulation experiments to demonstrate the effectiveness of the proposed reputation-based security scheme. And our simulation results show that the proposed security scheme can enhance the security and, hence, improve the accuracy of sensor localization in hostile or untrusted environments.

  11. Ciguatera fish poisoning in la Habana, Cuba: a study of local social-ecological resilience.

    Science.gov (United States)

    Morrison, Karen; Aguiar Prieto, Pablo; Castro Domínguez, Arnaldo; Waltner-Toews, David; Fitzgibbon, John

    2008-09-01

    Following the collapse of the Cuban economy in the early 1990s, epidemiologists in the Cuban Ministry of Health noticed dramatic increases in reported outbreaks of ciguatera fish poisoning (CFP) in some coastal communities. This article summarizes the results of a comparative case study which applied an ecosystem approach to human health to investigate this issue. Situated learning and complexity theories were used to interpret the results of the investigation. CFP outbreaks are influenced by a complex set of interactions between ecological and socioeconomic processes. This study found that the level of organization of the local sports fishing community and the degree of degradation of the local nearshore marine ecosystem appear to be key factors influencing the diverging levels of CFP outbreaks recorded in the 1990s in the communities studied.

  12. Eco-Polycentric Urban Systems: An Ecological Region Perspective for Network Cities

    Directory of Open Access Journals (Sweden)

    André Botequilha-Leitão

    2012-04-01

    Full Text Available The research presented in this paper is a work in progress. It provides linkages between the author’s earlier research under the sustainable land planning framework (SLP and emergent ideas and planning and design strategies, centered on the (landscape ecological dimension of cities’ sustainability. It reviews several concepts, paradigms, and metaphors that have been emerging during the last decade, which can contribute to expand our vision on city planning and design. Among other issues, city form—monocentric, polycentric, and diffused—is discussed. The hypothesis set forth is that cities can improve the pathway to sustainability by adopting intermediate, network urban forms such as polycentric urban systems (PUS under a broader vision (as compared to the current paradigm, to make way to urban ecological regions. It discusses how both the principles of SLP and those emergent ideas can contribute to integrate PUS with their functional hinterland, adopting an ecosystemic viewpoint of cities. It proposes to redirect the current dominant economic focus of PUS to include all of the other functions that are essential to urbanites, such as production (including the 3Rs, recreation, and ecology in a balanced way. Landscape ecology principles are combined with complexity science in order to deal with uncertainty to improve regional systems’ resilience. Cooperation in its multiple forms is seen as a fundamental social, but also economic process contributing to the urban network functioning, including its evolving capabilities for self-organization and adaptation.

  13. Malaria vectors in ecologically heterogeneous localities of the Colombian Pacific region.

    Directory of Open Access Journals (Sweden)

    Nelson Naranjo-Díaz

    Full Text Available The Colombian Pacific region is second nationally in number of malaria cases reported. This zone presents great ecological heterogeneity and Anopheles species diversity. However, little is known about the current spatial and temporal distribution of vector species. This study, conducted in three ecologically different localities of the Pacific region, aimed to evaluate the composition and distribution of Anopheles species and characterize transmission intensity. A total of 4,016 Anopheles mosquitoes were collected representing seven species. The composition and dominant species differed in each locality. Three species were infected with malaria parasites: Anopheles darlingi and An. calderoni were infected with Plasmodium falciparum and An. nuneztovari with Plasmodium vivax VK210 and VK247. Annual EIRs varied from 3.5-7.2 infective bites per year. These results confirm the importance of the primary vector An. nuneztovari in areas disturbed by human interventions, of An. darlingi in deforested margins of humid tropical rainforest and An. albimanus and the suspected vector An. calderoni in areas impacted by urbanization and large-scale palm oil agriculture close to the coast. This constitutes the first report in the Colombia Pacific region of naturally infected An. darlingi, and in Colombia of naturally infected An. calderoni. Further studies should evaluate the epidemiological importance of An. calderoni in the Pacific region.

  14. Risk, Networks, and Ecological Explanations for the Emergence of Cooperation in Commons Governance

    Directory of Open Access Journals (Sweden)

    Adam Douglas Henry

    2012-01-01

    Full Text Available The commons literature increasingly recognizes the importance of contextual factors in driving collaboration in governance systems. Of particular interest are the ways in which the attributes of a resource system influence the dynamics of cooperation. While this may occur through many pathways, we investigate the mechanisms by which ecological factors influence both the risk of cooperation as well as the density of networks in which strategic interactions take place. Both of these factors influence the co-evolutionary dynamics of network structure and cooperative behavior. These dynamics are investigated through agent-based simulations, which provide preliminary evidence that: 1 low-density networks support higher levels of cooperation, even in high-risk Prisoner's Dilemma scenarios; and 2 in high-risk scenarios, networks that develop higher levels of clustering generally enjoy higher societal gains.

  15. Ecological modules and roles of species in heathland plant-insect flower visitor networks

    DEFF Research Database (Denmark)

    Dupont, Yoko; Olesen, Jens Mogens

    2009-01-01

    1.  Co-existing plants and flower-visiting animals often form complex interaction networks. A long-standing question in ecology and evolutionary biology is how to detect nonrandom subsets (compartments, blocks, modules) of strongly interacting species within such networks. Here we use a network...... heathland sites in Denmark, separated by ≥ 10 km. Among sites, plant communities were similar, but composition of flower-visiting insect faunas differed. Visitation frequencies of visitor species were recorded as a measure of insect abundance. 3.  Qualitative (presence-absence) interaction networks were...... consisted of 1-6 plant species and 18-54 insect species. Interactions aggregated around one or two hub plant species, which were largely identical at the three study sites. 5.  Insect species were categorized in taxonomic groups, mostly at the level of orders. When weighted by visitation frequency, each...

  16. The Construction of Higher Education Entrepreneur Services Network System a Research Based on Ecological Systems Theory

    Science.gov (United States)

    Xue, Jingxin

    The article aims to completely, systematically and objectively analyze the current situation of Entrepreneurship Education in China with Ecological Systems Theory. From this perspective, the author discusses the structure, function and its basic features of higher education entrepreneur services network system, and puts forward the opinion that every entrepreneurship organization in higher education institution does not limited to only one platform. Different functional supporting platforms should be combined closed through composite functional organization to form an integrated network system, in which each unit would impels others' development.

  17. River Networks As Ecological Corridors for Species, Populations and Pathogens of Water-Borne Disease

    Science.gov (United States)

    Rinaldo, A.

    2014-12-01

    River basins are a natural laboratory for the study of the integration of hydrological, ecological and geomorphological processes. Moving from morphological and functional analyses of dendritic geometries observed in Nature over a wide range of scales, this Lecture addresses essential ecological processes that take place along dendritic structures, hydrology-driven and controlled, like e.g.: population migrations and human settlements, that historically proceeded along river networks to follow water supply routes; riparian ecosystems composition that owing to their positioning along streams play crucial roles in their watersheds and in the loss of biodiversity proceeding at unprecedented rates; waterborne disease spreading, like epidemic cholera that exhibits epidemic patterns that mirror those of watercourses and of human mobility and resurgences upon heavy rainfall. Moreover, the regional incidence of Schistosomiasis, a parasitic waterborne disease, and water resources developments prove tightly related, and proliferative kidney disease in fish thrives differently in pristine and engineered watercourses: can we establish quantitatively the critical linkages with hydrologic drivers and controls? How does connectivity within a river network affect community composition or the spreading mechanisms? Does the river basin act as a template for biodiversity or for species' persistence? Are there hydrologic controls on epidemics of water-borne disease? Here, I shall focus on the noteworthy scientific perspectives provided by spatially explicit eco-hydrological studies centered on river networks viewed as ecological corridors for species, populations and pathogens of waterborne disease. A notable methodological coherence is granted by the mathematical description of river networks as the support for reactive transport. The Lecture overviews a number of topics idiosyncratically related to my own research work but ideally aimed at a coherent body of materials and methods. A

  18. Antibiotic Treatment Expands the Resistance Reservoir and Ecological Network of the Phage Metagenome

    OpenAIRE

    Modi, Sheetal R.; Lee, Henry H.; Spina, Catherine S.; Collins, James J.

    2013-01-01

    The mammalian gut ecosystem has significant influence on host physiology 1–4 , but the mechanisms that sustain this complex environment in the face of different stresses remain obscure. Perturbations to this ecosystem, such as through antibiotic treatment or diet, are currently interpreted at the level of bacterial phylogeny 5–7 . Less is known about the contributions of the abundant population of phage to this ecological network. Here, we explore the phageome as a potential genetic reservoir...

  19. Towards Optimal Event Detection and Localization in Acyclic Flow Networks

    KAUST Repository

    Agumbe Suresh, Mahima

    2012-01-03

    Acyclic flow networks, present in many infrastructures of national importance (e.g., oil & gas and water distribution systems), have been attracting immense research interest. Existing solutions for detecting and locating attacks against these infrastructures, have been proven costly and imprecise, especially when dealing with large scale distribution systems. In this paper, to the best of our knowledge for the first time, we investigate how mobile sensor networks can be used for optimal event detection and localization in acyclic flow networks. Sensor nodes move along the edges of the network and detect events (i.e., attacks) and proximity to beacon nodes with known placement in the network. We formulate the problem of minimizing the cost of monitoring infrastructure (i.e., minimizing the number of sensor and beacon nodes deployed), while ensuring a degree of sensing coverage in a zone of interest and a required accuracy in locating events. We propose algorithms for solving these problems and demonstrate their effectiveness with results obtained from a high fidelity simulator.

  20. MAILROOM- A LOCAL AREA NETWORK ELECTRONIC MAIL PROGRAM

    Science.gov (United States)

    Weiner, M. J.

    1994-01-01

    The Mailroom program is a Local Area Network (LAN) electronic mail program. It allows LAN users to electronically exchange notes, letters, reminders, or any sort of communication via their computer. The Mailroom program links all LAN users into a communication circle where messages can be created, sent, copied, printed, downloaded, uploaded, and deleted through a series of menu-driven screens. Mailroom includes a feature which allows users to determine if a message they have sent has been read by the receiver. Each user must be separately installed and removed from Mailroom as they join or leave the network. Mailroom comes with a program that accomplishes this with minimum of effort on the part of the Network Administrator/Manager. There is also a program that allows the Network Administrator/Manager to install Mailroom on each user's workstation so that on execution of Mailroom the user's station may be identified and the configurations settings activated. It will create its own configuration and data/supporting files during the setup and installation process. The Mailroom program is written in Microsoft QuickBasic. It was developed to run on networked IBM XT/ATs or compatibles and requires that all participating workstations share a common drive. It has been implemented under DOS 3.2 and has a memory requirement of 71K. Mailroom was developed in 1988.

  1. Mathematical modeling of local perfusion in large distensible microvascular networks

    Science.gov (United States)

    Causin, Paola; Malgaroli, Francesca

    2017-08-01

    Microvessels -blood vessels with diameter less than 200 microns- form large, intricate networks organized into arterioles, capillaries and venules. In these networks, the distribution of flow and pressure drop is a highly interlaced function of single vessel resistances and mutual vessel interactions. In this paper we propose a mathematical and computational model to study the behavior of microcirculatory networks subjected to different conditions. The network geometry is composed of a graph of connected straight cylinders, each one representing a vessel. The blood flow and pressure drop across the single vessel, further split into smaller elements, are related through a generalized Ohm's law featuring a conductivity parameter, function of the vessel cross section area and geometry, which undergo deformations under pressure loads. The membrane theory is used to describe the deformation of vessel lumina, tailored to the structure of thick-walled arterioles and thin-walled venules. In addition, since venules can possibly experience negative transmural pressures, a buckling model is also included to represent vessel collapse. The complete model including arterioles, capillaries and venules represents a nonlinear system of PDEs, which is approached numerically by finite element discretization and linearization techniques. We use the model to simulate flow in the microcirculation of the human eye retina, a terminal system with a single inlet and outlet. After a phase of validation against experimental measurements, we simulate the network response to different interstitial pressure values. Such a study is carried out both for global and localized variations of the interstitial pressure. In both cases, significant redistributions of the blood flow in the network arise, highlighting the importance of considering the single vessel behavior along with its position and connectivity in the network.

  2. Locally supervised neural networks for approximating terramechanics models

    Science.gov (United States)

    Song, Xingguo; Gao, Haibo; Ding, Liang; Spanos, Pol D.; Deng, Zongquan; Li, Zhijun

    2016-06-01

    Neural networks (NNs) have been widely implemented for identifying nonlinear models, and predicting the distribution of targets, due to their ability to store and learn training samples. However, for highly complex systems, it is difficult to build a robust global network model, and efficiently managing the large amounts of experimental data is often required in real-time applications. In this paper, an effective method for building local models is proposed to enhance robustness and learning speed in globally supervised NNs. Unlike NNs, Gaussian processes (GP) produce predictions that capture the uncertainty inherent in actual systems, and typically provides superior results. Therefore, in this study, each local NN is learned in the same manner as a Gaussian process. A mixture of local model NNs is created and then augmented using weighted regression. This proposed method, referred to as locally supervised NN for weighted regression like GP, is abbreviated as "LGPN", is utilized for approximating a wheel-terrain interaction model under fixed soil parameters. The prediction results show that the proposed method yields significant robustness, modeling accuracy, and rapid learning speed.

  3. Measuring foliar chemistry alongside airborne observations in the National Ecological Observatory Network

    Science.gov (United States)

    Weintraub, S. R.; Meier, C. L.; Goulden, T.; Leisso, N.; Petroy, S. B.

    2016-12-01

    The chemical composition of canopy foliage mediates key ecosystem processes including productivity, herbivory and nutrient export. However, long-term datasets that can reveal directional change in canopy foliar traits in response to environmental drivers are scarce. Advances in imaging spectroscopy have enhanced our ability to remotely sense canopy reflectance, and a better understanding of links between observed reflectance and measured foliar constituents will enhance our ability to map unsampled regions and predict foliar chemical change over time. In this talk, I will present the current canopy foliage sampling plan for the National Ecological Observatory Network (NEON). NEON will analyze sun-lit canopy leaves and needles across all 47 terrestrial observation sites every 3-5 years throughout the 30-year lifetime of the observatory. Sampling will occur in plots adjacent to flux towers as well as those distributed across the landscape, with individuals targeted to represent locally dominant canopy species. Measured variables include leaf mass per area, chlorophyll content, carbon and nitrogen concentrations and stable isotopes, major and minor elements, and lignin. Sampling will coincide with overflights of the NEON Airborne Observation Platform in order to maximize the utility of ground-based observations for developing regressions with hyperspectral data, with algorithm development lead by the community. To demonstrate the kind of data that will be collected and made publicly available once the observatory becomes operational, results from three linked ground-aerial prototype campaigns from summer 2016 will be shown. Prototype data highlights strong taxonomic controls on foliar physical and chemical properties but also notable variation within species and genera across sites and environmental gradients. NEON's canopy sampling program will hopefully provide exciting, continental-scale opportunities to advance our understanding of the controls on foliar chemistry

  4. An online database for informing ecological network models: http://kelpforest.ucsc.edu

    Science.gov (United States)

    Beas-Luna, Rodrigo; Tinker, M. Tim; Novak, Mark; Carr, Mark H.; Black, August; Caselle, Jennifer E.; Hoban, Michael; Malone, Dan; Iles, Alison C.

    2014-01-01

    Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/data​baseui).

  5. Constructing Ecological Networks Based on Habitat Quality Assessment: A Case Study of Changzhou, China

    Science.gov (United States)

    Gao, Yu; Ma, Lei; Liu, Jiaxun; Zhuang, Zhuzhou; Huang, Qiuhao; Li, Manchun

    2017-01-01

    Fragmentation and reduced continuity of habitat patches threaten the environment and biodiversity. Recently, ecological networks are increasingly attracting the attention of researchers as they provide fundamental frameworks for environmental protection. This study suggests a set of procedures to construct an ecological network. First, we proposed a method to construct a landscape resistance surface based on the assessment of habitat quality. Second, to analyze the effect of the resistance surface on corridor simulations, we used three methods to construct resistance surfaces: (1) the method proposed in this paper, (2) the entropy coefficient method, and (3) the expert scoring method. Then, we integrated habitat patches and resistance surfaces to identify potential corridors using graph theory. These procedures were tested in Changzhou, China. Comparing the outputs of using different resistance surfaces demonstrated that: (1) different landscape resistance surfaces contribute to how corridors are identified, but only slightly affect the assessment of the importance of habitat patches and potential corridors; (2) the resistance surface, which is constructed based on habitat quality, is more applicable to corridor simulations; and (3) the assessment of the importance of habitat patches is fundamental for ecological network optimization in the conservation of critical habitat patches and corridors. PMID:28393879

  6. An online database for informing ecological network models: http://kelpforest.ucsc.edu.

    Science.gov (United States)

    Beas-Luna, Rodrigo; Novak, Mark; Carr, Mark H; Tinker, Martin T; Black, August; Caselle, Jennifer E; Hoban, Michael; Malone, Dan; Iles, Alison

    2014-01-01

    Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/) to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training). To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/databaseui).

  7. Constructing Ecological Networks Based on Habitat Quality Assessment: A Case Study of Changzhou, China

    Science.gov (United States)

    Gao, Yu; Ma, Lei; Liu, Jiaxun; Zhuang, Zhuzhou; Huang, Qiuhao; Li, Manchun

    2017-04-01

    Fragmentation and reduced continuity of habitat patches threaten the environment and biodiversity. Recently, ecological networks are increasingly attracting the attention of researchers as they provide fundamental frameworks for environmental protection. This study suggests a set of procedures to construct an ecological network. First, we proposed a method to construct a landscape resistance surface based on the assessment of habitat quality. Second, to analyze the effect of the resistance surface on corridor simulations, we used three methods to construct resistance surfaces: (1) the method proposed in this paper, (2) the entropy coefficient method, and (3) the expert scoring method. Then, we integrated habitat patches and resistance surfaces to identify potential corridors using graph theory. These procedures were tested in Changzhou, China. Comparing the outputs of using different resistance surfaces demonstrated that: (1) different landscape resistance surfaces contribute to how corridors are identified, but only slightly affect the assessment of the importance of habitat patches and potential corridors; (2) the resistance surface, which is constructed based on habitat quality, is more applicable to corridor simulations; and (3) the assessment of the importance of habitat patches is fundamental for ecological network optimization in the conservation of critical habitat patches and corridors.

  8. The Next Generation of Scientists: Examining the Experiences of Graduate Students in Network-Level Social-Ecological Science

    Directory of Open Access Journals (Sweden)

    Michele Romolini

    2013-09-01

    Full Text Available By integrating the research and resources of hundreds of scientists from dozens of institutions, network-level science is fast becoming one scientific model of choice to address complex problems. In the pursuit to confront pressing environmental issues such as climate change, many scientists, practitioners, policy makers, and institutions are promoting network-level research that integrates the social and ecological sciences. To understand how this scientific trend is unfolding among rising scientists, we examined how graduate students experienced one such emergent social-ecological research initiative, Integrated Science for Society and Environment, within the large-scale, geographically distributed Long Term Ecological Research (LTER Network. Through workshops, surveys, and interviews, we found that graduate students faced challenges in how they conceptualized and practiced social-ecological research within the LTER Network. We have presented these conceptual challenges at three scales: the individual/project, the LTER site, and the LTER Network. The level of student engagement with and knowledge of the LTER Network was varied, and students faced different institutional, cultural, and logistic barriers to practicing social-ecological research. These types of challenges are unlikely to be unique to LTER graduate students; thus, our findings are relevant to other scientific networks implementing new social-ecological research initiatives.

  9. Interpreting participatory Fuzzy Cognitive Maps as complex networks in the social-ecological systems of the Amazonian forests

    Science.gov (United States)

    Varela, Consuelo; Tarquis, Ana M.; Blanco-Gutiérrez, Irene; Estebe, Paloma; Toledo, Marisol; Martorano, Lucieta

    2015-04-01

    Social-ecological systems are linked complex systems that represent interconnected human and biophysical processes evolving and adapting across temporal and spatial scales. In the real world, social-ecological systems pose substantial challenges for modeling. In this regard, Fuzzy Cognitive Maps (FCMs) have proven to be a useful method for capturing the functioning of this type of systems. FCMs are a semi-quantitative type of cognitive map that represent a system composed of relevant factors and weighted links showing the strength and direction of cause-effects relationships among factors. Therefore, FCMs can be interpreted as complex system structures or complex networks. In this sense, recent research has applied complex network concepts for the analysis of FCMs that represent social-ecological systems. Key to FCM the tool is its potential to allow feedback loops and to include stakeholder knowledge in the construction of the tool. Also, previous research has demonstrated their potential to represent system dynamics and simulate the effects of changes in the system, such as policy interventions. For illustrating this analysis, we have developed a series of participatory FCM for the study of the ecological and human systems related to biodiversity conservation in two case studies of the Amazonian region, the Bolivia lowlands of Guarayos and the Brazil Tapajos National forest. The research is carried out in the context of the EU project ROBIN1 and it is based on the development of a series of stakeholder workshops to analyze the current state of the socio-ecological environment in the Amazonian forest, reflecting conflicts and challenges for biodiversity conservation and human development. Stakeholders included all relevant actors in the local case studies, namely farmers, environmental groups, producer organizations, local and provincial authorities and scientists. In both case studies we illustrate the use of complex networks concepts, such as the adjacency

  10. The effect of faulty local detectors on a detection network.

    CERN Document Server

    Mirjalily, G

    2002-01-01

    Distributed detection theory has received increasing attention recently. Development of multiple sensors for signal detection results in improved performance and increased reliability. in a detection network, each local sensor decides locally whether a signal is detected or not. The local decisions are sent to the fusion center, where the final decision is made. In this paper, a theoretic approach is considered to data fusion when one of the sensors is faulty. If the fusion center does not have any knowledge of this fault, the performance of the system is different than its normal performance. The changes in the error probabilities depend on the type of the fault and on the threshold value of the fission center test. We derived some expressions of the changes in the values of error probabilities. For some type of faults, the system false alarm probability increases significantly, whereas for some other faults, the system detection probability decreases significantly. To illustrate the results, a numerical exa...

  11. Distributed Plume Source Localization Using Hierarchical Sensor Networks

    Institute of Scientific and Technical Information of China (English)

    KUANG Xing-hong; LIU Yu-qing; WU Yan-xiang; SHAO Hui-he

    2009-01-01

    A hierarchical wireless sensor networks (WSN) was proposed to estimate the plume source location. Such WSN can be of tremendous help to emergency personnel trying to protect people from terrorist attacks or responding to an accident. The entire surveillant field is divided into several small sub-regions. In each sub-region, the localization algorithm based on the improved particle filter (IPF) was performed to estimate the location. Some improved methods such as weighted centroid, residual resampling were introduced to the IPF algorithm to increase the localization performance. This distributed estimation method elirninates many drawbacks inherent with the traditional centralized optimization method. Simulation results show that localization algorithm is efficient far estimating the plume source location.

  12. Towards a network of locally managed marine areas (LMMAs in the Western Indian Ocean.

    Directory of Open Access Journals (Sweden)

    Steve Rocliffe

    Full Text Available In the Western Indian Ocean (WIO, local communities are increasingly assuming responsibility for inshore marine resources either on their own or through collaborative management arrangements with governments or non-state actors. In this paper, we trace the evolution and expansion of community management in the WIO and present the first ever inventory and assessment of the region's locally managed marine areas (LMMAs. We compare the key attributes of these areas to those under government stewardship and assess their relative contributions to progress towards the Convention on Biodiversity (CBD target of 10% of marine and coastal ecological regions to be effectively conserved by 2020. We also explore the legal frameworks that underpin locally managed marine initiatives in Kenya, Madagascar, Mozambique and Tanzania to assess the potential for future expansion. A principal finding is that whilst LMMAs protect more than 11,000 square kilometres of marine resource in the WIO, they are hampered by underdeveloped local and national legal structures and enforcement mechanisms. In our recommendations to improve local management, we suggest establishing a network of LMMA practitioners in the WIO region to share experiences and best practice.

  13. From the Experience of Revitalization of Ecological and Local Lore Student Initiatives of Izmail State University for Humanities

    Directory of Open Access Journals (Sweden)

    Gramatik N.V.

    2016-08-01

    Full Text Available The urgency of the problem of ecological education of students of local lore is its connection with the decision of the major problems of pedagogy, as the problem of the formation of personality, all its moral side, and including - a responsible attitude to nature. Ecological and local history education in the vocational training system, opens the future specialist the world with all the versatility of the complex nature of the relationship, it promotes the formation of personal qualities and values. In this regard, the main objective of the educational process in higher education is study ways to enhance eco-initiatives of local history students.

  14. Report: Results of Technical Network Vulnerability Assessment: EPA’s National Health & Environment Effects Research Laboratory, Western Ecology Division

    Science.gov (United States)

    Report #11-P-0429, August 3, 2011. Vulnerability testing of EPA’s NHEERL Western Ecology Division network conducted in March 2011 identified Internet Protocol addresses with numerous high-risk and medium-risk vulnerabilities.

  15. Ecological networks as a new approach for nature conservation in Turkey: A case study of Izmir Province

    NARCIS (Netherlands)

    Hepcan, C.C.; Bouwma, I.M.; Jongman, R.H.G.; Ozkan, M.B.

    2009-01-01

    This paper aims to identify and evaluate a potential ecological network including core areas and large-scale corridors in the ¿zmir Province and its surrounding areas, Turkey. It is one of the first studies on the connectivity for mammal species and the detection of potential ecological corridors fo

  16. Fully Connected Neural Networks Ensemble with Signal Strength Clustering for Indoor Localization in Wireless Sensor Networks

    OpenAIRE

    2015-01-01

    The paper introduces a method which improves localization accuracy of the signal strength fingerprinting approach. According to the proposed method, entire localization area is divided into regions by clustering the fingerprint database. For each region a prototype of the received signal strength is determined and a dedicated artificial neural network (ANN) is trained by using only those fingerprints that belong to this region (cluster). Final estimation of the location is obtained by fusion ...

  17. Neighborhoods and adolescent health-risk behavior: an ecological network approach.

    Science.gov (United States)

    Browning, Christopher R; Soller, Brian; Jackson, Aubrey L

    2015-01-01

    This study integrates insights from social network analysis, activity space perspectives, and theories of urban and spatial processes to present an novel approach to neighborhood effects on health-risk behavior among youth. We suggest spatial patterns of neighborhood residents' non-home routines may be conceptualized as ecological, or "eco"-networks, which are two-mode networks that indirectly link residents through socio-spatial overlap in routine activities. We further argue structural configurations of eco-networks are consequential for youth's behavioral health. In this study we focus on a key structural feature of eco-networks--the neighborhood-level extent to which household dyads share two or more activity locations, or eco-network reinforcement--and its association with two dimensions of health-risk behavior, substance use and delinquency/sexual activity. Using geographic data on non-home routine activity locations among respondents from the Los Angeles Family and Neighborhood Survey (L.A.FANS), we constructed neighborhood-specific eco-networks by connecting sampled households to "activity clusters," which are sets of spatially-proximate activity locations. We then measured eco-network reinforcement and examined its association with dimensions of adolescent health risk behavior employing a sample of 830 youth ages 12-17 nested in 65 census tracts. We also examined whether neighborhood-level social processes (collective efficacy and intergenerational closure) mediate the association between eco-network reinforcement and the outcomes considered. Results indicated eco-network reinforcement exhibits robust negative associations with both substance use and delinquency/sexual activity scales. Eco-network reinforcement effects were not explained by potential mediating variables. In addition to introducing a novel theoretical and empirical approach to neighborhood effects on youth, our findings highlight the importance of intersecting conventional routines for

  18. Wireless local area network in a prehospital environment

    Directory of Open Access Journals (Sweden)

    Grimes Gary J

    2004-08-01

    Full Text Available Abstract Background Wireless local area networks (WLANs are considered the next generation of clinical data network. They open the possibility for capturing clinical data in a prehospital setting (e.g., a patient's home using various devices, such as personal digital assistants, laptops, digital electrocardiogram (EKG machines, and even cellular phones, and transmitting the captured data to a physician or hospital. The transmission rate is crucial to the applicability of the technology in the prehospital setting. Methods We created two separate WLANs to simulate a virtual local are network environment such as in a patient's home or an emergency room (ER. The effects of different methods of data transmission, number of clients, and roaming among different access points on the file transfer rate were determined. Results The present results suggest that it is feasible to transfer small files such as patient demographics and EKG data from the patient's home to the ER at a reasonable speed. Encryption, user control, and access control were implemented and results discussed. Conclusions Implementing a WLAN in a centrally managed and multiple-layer-controlled access control server is the key to ensuring its security and accessibility. Future studies should focus on product capacity, speed, compatibility, interoperability, and security management.

  19. Local communities obstruct global consensus: Naming game on multi-local-world networks

    CERN Document Server

    Lou, Yang; Fan, Zhengping; Xiang, Luna

    2016-01-01

    Community structure is essential for social communications, where individuals belonging to the same community are much more actively interacting and communicating with each other than those in different communities within the human society. Naming game, on the other hand, is a social communication model that simulates the process of learning a name of an object within a community of humans, where the individuals can reach global consensus on naming an object asymptotically through iterative pair-wise conversations. The underlying communication network indicates the relationships among the individuals. In this paper, three typical topologies of human communication networks, namely random-graph, small-world and scale-free networks, are employed, which are embedded with the multi-local-world community structure, to study the naming game. Simulations show that 1) when the intra-community connections increase while the inter-community connections remain to be unchanged, the convergence to global consensus is slow ...

  20. Synchronization unveils the organization of ecological networks with positive and negative interactions

    Science.gov (United States)

    Girón, Andrea; Saiz, Hugo; Bacelar, Flora S.; Andrade, Roberto F. S.; Gómez-Gardeñes, Jesús

    2016-06-01

    Network science has helped to understand the organization principles of the interactions among the constituents of large complex systems. However, recently, the high resolution of the data sets collected has allowed to capture the different types of interactions coexisting within the same system. A particularly important example is that of systems with positive and negative interactions, a usual feature appearing in social, neural, and ecological systems. The interplay of links of opposite sign presents natural difficulties for generalizing typical concepts and tools applied to unsigned networks and, moreover, poses some questions intrinsic to the signed nature of the network, such as how are negative interactions balanced by positive ones so to allow the coexistence and survival of competitors/foes within the same system? Here, we show that synchronization phenomenon is an ideal benchmark for uncovering such balance and, as a byproduct, to assess which nodes play a critical role in the overall organization of the system. We illustrate our findings with the analysis of synthetic and real ecological networks in which facilitation and competitive interactions coexist.

  1. Localized Recursive Estimation in Energy Constrained Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Bang Wang

    2006-06-01

    Full Text Available This paper proposes a localized recursive estimation scheme for parameter estimation in wireless sensor networks. Given any parameter of a target occurring at some location and time, a number of sensors recursively estimate the parameter by using their local measurements of the parameter that is attenuated with the distance between a sensor and the target location and corrupted by noise. Compared with centralized estimation schemes that transmit all encoded measurements to a sink (or a fusion center, the recursive scheme needs only to transmit the final estimate to a sink. When the sink is faraway from the sensors and multihop communications have to be used, using localized recursive estimation can help to reduce energy consumption and reduce network traffic load. A sensor sequence with the fastest convergence rate is identified, by which the variance of estimation error reduces faster than all other sequences. In the case of adjustable transmission power, a heuristic has been proposed to find a sensor sequence with the minimum total transmission power when performing the recursive estimation. Numerical examples have been used to compare the performance of the proposed scheme with that of a centralized estimation scheme and have also shown the effectiveness of the proposed heuristic.

  2. Local Positioning Services on IEEE 802.11 Networks

    Directory of Open Access Journals (Sweden)

    A. M. Vegni

    2008-06-01

    Full Text Available This paper deals with localization services in IEEE 802.11 networks, for indoor environment. The proposed solution processes the Time Of Arrival of location packets sent by a Mobile Terminal, that makes access in a IEEE 802.11 network. A set of Location Supporting Nodes and a Location Support Server composes an indoor location services architecture. A fully compatible IEEE 802.11 Localization Services protocol supporting data exchange related to both TOA measurement and processing is reported. Simulation results show the method efficiency in both IEEE 802.11 PCF and DCF modes. Assessment of the maximum number of users for which location services can be provided is also reported. Since high localization accuracy requires large bandwidth, a broadband antenna for LSN and LSS was designed. The related results are reported in the second part of the paper. The antenna works at 5.0 GHz (centre frequency in broadband mode and is matched on the wireless operating frequencies with a percentage more than 8% (1:1.5 VSWR.

  3. Local Events and Dynamics on Weighted Complex Networks

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hui; GAO Zi-You

    2006-01-01

    @@ We examine the weighted networks grown and evolved by local events, such as the addition of new vertices and links and we show that depending on frequency of the events, a generalized power-law distribution of strength can emerge. Continuum theory is used to predict the scaling function as well as the exponents, which is in good agreement with the numerical simulation results. Depending on event frequency, power-law distributions of degree and weight can also be expected. Probability saturation phenomena for small strength and degree in many real world networks can be reproduced. Particularly, the non-trivial clustering coefficient, assortativity coefficient and degree-strength correlation in our model are all consistent with empirical evidences.

  4. Quality of local control for simple sewer networks

    Science.gov (United States)

    Kolechkina, Alla; van Nooijen, Ronald

    2016-04-01

    Combined sewer networks, where both foul water and storm water are transported through the same system, tend to develop into complex networks due to expansion of towns and villages. The transport capacity of these systems is always limited, so occasional controlled spills into surface water, combined sewer overflows (CSO), are part of the normal operating procedure. Occasionally the ideas and rules present in the original design are not respected when the system is extended to cover a larger area. One way to deal with this problem is to implement central control. Another is to add pipes and hardware to bring the extended system into line with the original rules and ideas. We show that for a design rule often followed in the Netherlands, local control does quite well as long as the rule is respected and there are no large variations in precipitation intensity over the area covered by the system.

  5. A Biophysical Model for Hawaiian Coral Reefs: Coupling Local Ecology, Larval Transport and Climate Change

    Science.gov (United States)

    Kapur, M. R.

    2016-02-01

    Simulative models of reef ecosystems have been used to evaluate ecological responses to a myriad of disturbance events, including fishing pressure, coral bleaching, invasion by alien species, and nutrient loading. The Coral Reef Scenario Evaluation Tool (CORSET), has been developed and instantiated for both the Meso-American Reef (MAR) and South China Sea (SCS) regions. This model is novel in that it accounts for the many scales at which reef ecosystem processes take place; is comprised of a "bottom-up" structure wherein complex behaviors are not pre-programmed, but emergent and highly portable to new systems. Local-scale dynamics are coupled across regions through larval connectivity matrices, derived sophisticated particle transport simulations that include key elements of larval behavior. By this approach, we are able to directly evaluate some of the potential consequences of larval connectivity patterns across a range of spatial scales and under multiple climate scenarios. This work develops and applies the CORSET (Coral Reef Scenario Evaluation Tool) to the Main Hawaiian Islands under a suite of climate and ecological scenarios. We introduce an adaptation constant into reef-building coral dynamics to simulate observed resiliencies to bleaching events. This presentation will share results from the model's instantiation under two Resource Concentration Pathway climate scenarios, with emphasis upon larval connectivity dynamics, emergent coral tolerance to increasing thermal anomalies, and patterns of spatial fishing closures. Results suggest that under a business-as-usual scenario, thermal tolerance and herbivore removal will have synergistic effects on reef resilience.

  6. Bayesian network approach for modeling local failure in lung cancer

    Science.gov (United States)

    Oh, Jung Hun; Craft, Jeffrey; Al-Lozi, Rawan; Vaidya, Manushka; Meng, Yifan; Deasy, Joseph O; Bradley, Jeffrey D; Naqa, Issam El

    2011-01-01

    Locally advanced non-small cell lung cancer (NSCLC) patients suffer from a high local failure rate following radiotherapy. Despite many efforts to develop new dose-volume models for early detection of tumor local failure, there was no reported significant improvement in their application prospectively. Based on recent studies of biomarker proteins’ role in hypoxia and inflammation in predicting tumor response to radiotherapy, we hypothesize that combining physical and biological factors with a suitable framework could improve the overall prediction. To test this hypothesis, we propose a graphical Bayesian network framework for predicting local failure in lung cancer. The proposed approach was tested using two different datasets of locally advanced NSCLC patients treated with radiotherapy. The first dataset was collected retrospectively, which is comprised of clinical and dosimetric variables only. The second dataset was collected prospectively in which in addition to clinical and dosimetric information, blood was drawn from the patients at various time points to extract candidate biomarkers as well. Our preliminary results show that the proposed method can be used as an efficient method to develop predictive models of local failure in these patients and to interpret relationships among the different variables in the models. We also demonstrate the potential use of heterogenous physical and biological variables to improve the model prediction. With the first dataset, we achieved better performance compared with competing Bayesian-based classifiers. With the second dataset, the combined model had a slightly higher performance compared to individual physical and biological models, with the biological variables making the largest contribution. Our preliminary results highlight the potential of the proposed integrated approach for predicting post-radiotherapy local failure in NSCLC patients. PMID:21335651

  7. Wireless Local Area Network Adaptive Modulation and Coding Technology Research

    Institute of Scientific and Technical Information of China (English)

    SUN Zeng-you; SUN Xiao-fan

    2012-01-01

      Expound the existing modulation mode of the present wireless local area network. Directing at the problem that when single modulation method conveys data with high speed in the frequency selective fading channel, the system throughput will be declined and the efficiency of the spectrum will be lowered . Put forward the scheme that the OFDM sub-carrier will use differ⁃ent modulation modes after dynamic groups by amplitude frequency response. Simulation results show that the scheme will lower the complexity of the system achievement, and can get a higher spectrum efficiency.

  8. Fishing Practices in the Galapagos Islands: The Local Struggle Approached Through Two Political Ecology Theses

    Directory of Open Access Journals (Sweden)

    Brittany MacGillivray

    2011-10-01

    Full Text Available Overexploitation and illegal fishing continues to be a problem within the Galapagos Marine Reserve. Local compliance regarding conservation initiatives and the regulations governing the access to, and use of marine resources is exacerbating these problems. The conservation and control thesis and the degradation and marginalization thesis from political ecology were applied to the current issues in the Marine Reserve as an attempt to understand behaviour motivation. Commonalities among these theses suggest a socio-political struggle where government and international agencies are discrediting local values and livelihood, and are encouraging the overexploitation of their resources. Future management should strive to understand and address these motivations; working with and encouraging the inclusion of local communities into management regimes to ultimately ensure compliance, community empowerment, and the long-term sustainable use of marine resources and the integrity of the marine ecosystems in the Galapagos Islands.  

  9. Networked Intermedia Agenda Setting: The Geography of a Hyperlinked Scandinavian News Ecology

    DEFF Research Database (Denmark)

    Sjøvaag, Helle; Stavelin, Eirik; Karlsson, Michael

    How does agenda setting work within the hyperlinked Scandinavian news ecology? This paper investigates intermedia agenda setting within and between the local, regional, national and supra-national levels in Sweden, Denmark and Norway; analyses the center/periphery dimensions of hyperlink connecti......, social geography and hyperlinked news agendas in Scandinavia, adding to the research on the political implications of the Internet on national public spheres....

  10. Global Ecological Signpost, Local Reality: The Moraballi Creek Studies in Guyana and What Happened Afterwards

    Directory of Open Access Journals (Sweden)

    Janette Bulkan

    2016-12-01

    Full Text Available There is a common assumption that when sustainable forest management (SFM is not practised the reasons are usually a lack of knowledge or lack of training in applying those techniques. We trace the intermittent development of techniques for SFM in the tropical rainforest of Guyana (South America, beginning with the classical observational ecology at Moraballi Creek in 1929. We reference the deliberate lack of application of SFM in spite of access to science-based information and repeated training. In this country, a precarious political democracy is destabilised by the gigantic profits from illegal logging and log trading which support corruption in the sector and generally across regulatory systems. The highest rate of graduate emigration in the world contributes to the difficulty of creating the core of moral leadership required to rise above the local tradition of under-the-table negotiation in place of the rule of law.

  11. Local perceptions of changes in traditional ecological knowledge: a case study from Malekula island, Vanuatu.

    Science.gov (United States)

    McCarter, Joe; Gavin, Michael C

    2014-04-01

    Traditional ecological knowledge (TEK) is a critical global resource that may be eroding amid social and environmental change. Here, we present data on local perceptions of TEK change from three communities on Malekula Island in Vanuatu. Utilizing a structured interview (n = 120), we find a common perception of TEK loss. Participants defined two key periods of TEK erosion (roughly 1940-1960 and 1980-present), and noted that TEK decline was driven both external (e.g., church) and internal (e.g., shifting values) processes. Erosion was perceived to more comprehensive in the worldview domain than in aspects of ethnobiological knowledge and practice. These data indicate the perceived fragility of TEK systems and the complexity of TEK change. TEK systems are critical to natural resource management, and data such as these will assist in designing nuanced responses to the ongoing loss of cultural knowledge and practice.

  12. Power Grid Network Evolutions for Local Energy Trading

    CERN Document Server

    Pagani, Giuliano Andrea

    2012-01-01

    The shift towards a energy Grid dominated by prosumers (consumers and producers of energy) will inevitably have repercussions on the distribution infrastructure. Today it is a hierarchical one designed to deliver energy from large scale facilities to end-users. Tomorrow it will be a capillary infrastructure at the medium and Low Voltage levels that will support local energy trading among prosumers. In our previous work, we analyzed the Dutch Power Grid and made an initial analysis of the economic impact topological properties have on decentralized energy trading. In this paper, we go one step further and investigate how different networks topologies and growth models facilitate the emergence of a decentralized market. In particular, we show how the connectivity plays an important role in improving the properties of reliability and path-cost reduction. From the economic point of view, we estimate how the topological evolutions facilitate local electricity distribution, taking into account the main cost ingredi...

  13. Local election blogs: Networking among the political elite

    DEFF Research Database (Denmark)

    Bock Segaard, Signe; Agger Nielsen, Jeppe

    2013-01-01

    : participants and interaction. Next, we apply our framework in a case study of election blogs in twelve Norwegian municipalities using multiple data sources. In contrast to the democratic vision of social media, our analysis demonstrates that election blogs are primarily used by those who are politically active......This article explores the role of social media (essentially blogs) in the 2011 Norwegian local election campaigns. We commence by developing a framework for investigating political communication using the social media that conceptualises the horizontal and vertical conversation along two dimensions...... in the local election campaign. While candidates say they want to connect with the electorate, in practice they are networking with each other. Our findings are discussed in light of the institutional setting in which the blogging take place, and the specific social media under investigation....

  14. Distributed localization using mobile beacons in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    KUANG Xing-hong; SHAO Hui-he

    2007-01-01

    A new distributed node localization algorithm named mobile beacons-improved particle filter (MB-IPF) was proposed. In the algorithm, the mobile nodes equipped with globe position system (GPS) move around in the wireless sensor network (WSN) field based on the Gauss-Markov mobility model, and periodically broadcast the beacon messages. Each unknown node estimates its location in a fully distributed mode based on the received mobile beacons. The localization algorithm is based on the IPF and several refinements, including the proposed weighted centroid algorithm, the residual resampling algorithm, and the markov chain monte carlo (MCMC) method etc., which were also introduced for performance improvement. The simulation results show that our proposed algorithm is efficient for most applications.

  15. Connected or informed?: Local Twitter networking in a London neighbourhood

    Directory of Open Access Journals (Sweden)

    John Bingham-Hall

    2015-08-01

    Full Text Available This paper asks whether geographically localised, or ‘hyperlocal’, uses of Twitter succeed in creating peer-to-peer neighbourhood networks or simply act as broadcast media at a reduced scale. Literature drawn from the smart cities discourse and from a UK research project into hyperlocal media, respectively, take on these two opposing interpretations. Evidence gathered in the case study presented here is consistent with the latter, and on this basis we criticise the notion that hyperlocal social media can be seen as a community in itself. We demonstrate this by creating a network map of Twitter followers of a popular hyperlocal blog in Brockley, southeast London. We describe various attributes of this network including its average degree and clustering coefficient to suggest that a small and highly connected cluster of visible local entities such as businesses form a clique at the centre of this network, with individual residents following these but not one another. We then plot the locations of these entities and demonstrate that sub-communities in the network are formed due to close geographical proximity between smaller sets of businesses. These observations are illustrated with qualitative evidence from interviews with users who suggest instead that rather than being connected to one another they benefit from what has been described as ‘neighbourhood storytelling’. Despite the limitations of working with Twitter data, we propose that this multi-modal approach offers a valuable way to investigate the experience of using social media as a communication tool in urban neighbourhoods.

  16. A localized coverage preserving protocol for wireless sensor networks.

    Science.gov (United States)

    Liu, Yuheng; Pu, Juhua; Zhang, Shuo; Liu, Yunlu; Xiong, Zhang

    2009-01-01

    In a randomly deployed and large scale wireless sensor network, coverage-redundant nodes consume much unnecessary energy. As a result, turning off these redundant nodes can prolong the network lifetime, while maintaining the degree of sensing coverage with a limited number of on-duty nodes. None of the off-duty eligibility rules in the literature, however, are sufficient and necessary conditions for eligible nodes. Hence redundancy or blind points might be incurred. In this paper we propose a complete Eligibility Rule based on Perimeter Coverage (ERPC) for a node to determine its eligibility for sleeping. ERPC has a computational complexity of O(N(2)log(N)), lower than the eligibility rule in the Coverage Control Protocol (CCP), O(N(3)), where N is the number of neighboring nodes. We then present a Coverage Preserving Protocol (CPP) to schedule the work state of eligible nodes. The main advantage of CPP over the Ottawa protocol lies in its ability to configure the network to any specific coverage degree, while the Ottawa protocol does not support different coverage configuration. Moreover, as a localized protocol, CPP has better adaptability to dynamic topologies than centralized protocols. Simulation results indicate that CPP can preserve network coverage with fewer active nodes than the Ottawa protocol. In addition, CPP is capable of identifying all the eligible nodes exactly while the CCP protocol might result in blind points due to error decisions. Quantitative analysis and experiments demonstrate that CPP can extend the network lifetime significantly while maintaining a given coverage degree.

  17. A Localized Coverage Preserving Protocol for Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Yuheng Liu

    2009-01-01

    Full Text Available In a randomly deployed and large scale wireless sensor network, coverage-redundant nodes consume much unnecessary energy. As a result, turning off these redundant nodes can prolong the network lifetime, while maintaining the degree of sensing coverage with a limited number of on-duty nodes. None of the off-duty eligibility rules in the literature, however, are sufficient and necessary conditions for eligible nodes. Hence redundancy or blind points might be incurred. In this paper we propose a complete Eligibility Rule based on Perimeter Coverage (ERPC for a node to determine its eligibility for sleeping. ERPC has a computational complexity of O(N2log(N, lower than the eligibility rule in the Coverage Control Protocol (CCP, O(N3, where N is the number of neighboring nodes. We then present a Coverage Preserving Protocol (CPP to schedule the work state of eligible nodes. The main advantage of CPP over the Ottawa protocol lies in its ability to configure the network to any specific coverage degree, while the Ottawa protocol does not support different coverage configuration. Moreover, as a localized protocol, CPP has better adaptability to dynamic topologies than centralized protocols. Simulation results indicate that CPP can preserve network coverage with fewer active nodes than the Ottawa protocol. In addition, CPP is capable of identifying all the eligible nodes exactly while the CCP protocol might result in blind points due to error decisions. Quantitative analysis and experiments demonstrate that CPP can extend the network lifetime significantly while maintaining a given coverage degree.

  18. [A study on the local marriage network in Korea].

    Science.gov (United States)

    Kim, J S

    1987-12-01

    Place of residence has traditionally been an important factor in Korea in mate selection. This study examines the local marriage network in Korean society, its variation by year of marriage, and general characteristics of the married women. Data are drawn from the 1986 national sample survey on the family life cycle implemented by the Korea Institute for Population and Health. Questionnaires were administered to 3013 wives aged 15-64. Major study findings follow. 1) The local marriage rate within the same region by birthplace is strikingly high in Kyongsangdo and Chonla-do. Local marriage rates are 79.5% in both of these regions, 33.5% in Seoul, 35.2% in Busan, 50% in Kyonggi-do, 48.1% in Kangwon-do, and 60.7% in Chungchung-do. 2) The local marriage rate within the same county or the same city be residence before marriage has rapidly been declining in rural areas since 1960. This is largely due to industrialization, urbanization, and better transportation. The marriage rate in rural areas was 62% among marriages in the 1940s, 47.1% in the 1960s, 43% in the 1980s, and 70.9%, 88.4%, and 70.7% respectively in urban areas. 3) The proportion of local marriages within the same city or county is 55.1% among arranged marriages and 72.3% among romantic marriages. 4) Pre-marital employment seems to have some effects on the extent of mate-selection. Wives who worked before marriage were more likely to marry men in the same city or county. The local marriage rate within the same city or county is 63.2% among wives with work experience, and 58.5% among wives without work experience. 5) The more educated the woman, the higher the local marriage rate within the same city or county. 56.6% of those who attended middle school married men in the same city or county as theirs, 61.4% of wives with a high school education, and 76.6% of wives with college or more education. 63.8% of wives who never attended school married men in the same city or county. In summary, restrictions on

  19. Drivers and barriers to the development of local food networks in rural Denmark

    DEFF Research Database (Denmark)

    Eriksen, Safania Normann; Sundbo, Jon

    2016-01-01

    This article examines the growing interest in local food by focusing on local food networks. The objective is to explore what factors drive or hinder the development of local food networks in rural Denmark. For this purpose, we have combined three bodies of theory: local food networks; entrepreneur....... The findings demonstrate that the main drivers of the development of local food networks are the pursuance of transparency and knowledge of origin, the existence of entrepreneurship potential, the coordination of networks by means of joint strategies, and the overcoming of conflict patterns. However...

  20. [Analysis of the design and renovation of mid-sized hospital's local area network].

    Science.gov (United States)

    Cao, Yang; Li, Min; Guo, Yifeng

    2011-11-01

    To address several hospital network issues, this paper discusses the overall plan, design and renovation of hospital's Local Area Network, making full use of existing network facilities. The techniques, such as Physical Separation of Internal and External Network, HSRP, OSPF, All-Routers Networking Model, etc., create features of extensibility, manageability, high safety, stability and so on to the overall network, and provide a reliable network platform to the function of the information systems.

  1. Local Ecological Knowledge Indicates Temporal Trends of Benthic Invertebrates Species of the Adriatic Sea

    Directory of Open Access Journals (Sweden)

    Azzurra Bastari

    2017-05-01

    Full Text Available In the Adriatic Sea, shifts in benthic community structure have been attributed to multiple stressors, from the effects of climate change to the impacts of commercial fishing. Some fishing practices, such as bottom trawling, have caused a widespread decline in exploited fish stocks. Bottom trawling is also expected to have negative impacts on benthic habitats, usually structured by and hosting a large array of invertebrate species, which provide important ecological services to fish and commercial invertebrate stocks. However, in contrast to commercial species for which long-term time series of the abundance exist, data on these habitat-forming invertebrates are scarce, as they are usually caught as bycatch and discarded. Therefore, there is great uncertainty about their long-term trends, and if these populations are stable or declining. Here we used interview surveys conducted with bottom-trawling fishers of the central Adriatic Sea to gather local ecological knowledge on megabenthos abundance occurring in their fishing domain, as an alternative source of information to conventional fisheries data. We interviewed 44 fishers, from the most important ports of the Marche region of Italy, to understand how megabenthic species have changed in abundance within the area since the 1980s. Specifically, we asked fishers to provide qualitative abundance scores for 18 invertebrate species in five phyla (Porifera, Cnidaria, Bryozoa, Mollusca, and Echinodermata based on their recollection of these species' presence in bycatch. We stratified responses in homogeneous temporal periods and geographic sectors of the study area, and analyzed their response with mixed effect ordered logistic regression models in order to evaluate spatiotemporal changes in the perceived abundance of each species. Our analysis suggests that the abundance of the sponge Geodia cydonium, the molluscs Pecten jacobaeus, Atrina fragilis, Neopycnodonte cochlear, and the group of

  2. Arctic Borderlands Ecological Knowledge Cooperative: can local knowledge inform caribou management?

    Directory of Open Access Journals (Sweden)

    Don E. Russell

    2013-06-01

    Full Text Available Normal 0 21 false false false SV X-NONE X-NONE While quantitative analyses have traditionally been used to measure overall caribou herd health, qualitative observational data can also provide timely information that reflects what people on the land are observing. The Arctic Borderlands Ecological Knowledge Co-op (ABEKC monitors ecological change in the range of the Porcupine Caribou Herd (PCH. The community-based monitoring component of the Co-op’s mandate involves the gathering of local knowledge through interviews with local experts in a number of communities.We analyzed the responses to interviews collected during 2000–2007 related to caribou availability, harvest success, meeting needs and caribou health during fall and spring. Interviews revealed 1 caribou greater availability during the survey period, 2 an increasing trend in the proportion of harvesters that met their needs 3 no trend in animals harvested or proportion of successful hunters and 4 improving overall caribou health throughout the period.There was no population estimate for the herd between 2001 and 2010. In 2001, 123,000 caribou were estimated in the herd. Based on an estimated 178,000 in 1989, a declining trend of ~ 3% annually occurred at least until 2001. In the interim agencies and boards feared the herd continued to decline and worked towards and finalized a Harvest Management Plan for the herd. In contrast, from the Co-op interviews all indications suggested improving herd conditions throughout most of the decade. A successful survey in 2010 determined the herd had grown to 169,000 animals. We conclude that the community-based interviews provided a valid, unique information source to better understand caribou ecology and express community perceptions of overall herd status and could provide a valuable contribution to management decision making.  We recommend that ABEKC results become standard input into Porcupine Caribou harvest management decisions and serve as a

  3. Local empathy provides global minimization of congestion in communication networks.

    Science.gov (United States)

    Meloni, Sandro; Gómez-Gardeñes, Jesús

    2010-11-01

    We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system's functioning up to the levels reached using global knowledge.

  4. Local empathy provides global minimization of congestion in communication networks

    Science.gov (United States)

    Meloni, Sandro; Gómez-Gardeñes, Jesús

    2010-11-01

    We present a mechanism to avoid congestion in complex networks based on a local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although leading to a sharp first-order-like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order-like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we present an outstanding example of how local dynamical rules can optimize the system’s functioning up to the levels reached using global knowledge.

  5. Study on Three-layered Grid Conceptual Prototype Using Ecological Network Computing Environment

    Institute of Scientific and Technical Information of China (English)

    GAO Lei; DING Yong-sheng; REN Li-hong

    2004-01-01

    Next generation grid systems where the emphasis shifts to distributed global collaboration, a service-oriented approach and information layer issues exhibit a strong sense of automation. Requirements for these systems resemble the self-organizing and the healing properties of natural ecosystems. Some key ecological concepts and mechanisms are introduced into the design for the third generation grid computing architectures by inspiration of this resemblance. Also, an Ecological Network-based Computing Environment (ENCE) platform is designed in this paper. Based on the ENCE platform, a grid-computing model of three-layered grid conceptual prototype that embeds the ENCE layers is presented from the viewpoint of implementation. The implementation model should be useful to the design of the third generation grid systems.

  6. Tick-, mosquito-, and rodent-borne parasite sampling designs for the National Ecological Observatory Network

    Science.gov (United States)

    Springer, Yuri P; Hoekman, David; Johnson, Pieter TJ; Duffy, Paul A; Hufft, Rebecca A.; Barnett, David T.; Allan, Brian F.; Amman, Brian R; Barker, Christopher M; Barrera, Roberto; Beard, Charles B; Beati, Lorenza; Begon, Mike; Blackmore, Mark S; Bradshaw, William E; Brisson, Dustin; Calisher, Charles H.; Childs, James E; Diuk-Wasser, Maria A.; Douglass, Richard J; Eisen, Rebecca J; Foley, Desmond H; Foley, Janet E.; Gaff, Holly D; Gardner, Scott L; Ginsberg, Howard; Glass, Gregory E; Hamer, Sarah A; Hayden, Mary H; Hjelle, Brian; Holzapfel, Christina M; Juliano, Steven A.; Kramer, Laura D.; Kuenzi, Amy J.; LaDeau, Shannon L.; Livdahl, Todd P.; Mills, James N.; Moore, Chester G.; Morand, Serge; Nasci, Roger S.; Ogden, Nicholas H.; Ostfeld, Richard S.; Parmenter, Robert R.; Piesman, Joseph; Reisen, William K.; Savage, Harry M.; Sonenshine, Daniel E.; Swei, Andrea; Yabsley, Michael J.

    2016-01-01

    Parasites and pathogens are increasingly recognized as significant drivers of ecological and evolutionary change in natural ecosystems. Concurrently, transmission of infectious agents among human, livestock, and wildlife populations represents a growing threat to veterinary and human health. In light of these trends and the scarcity of long-term time series data on infection rates among vectors and reservoirs, the National Ecological Observatory Network (NEON) will collect measurements and samples of a suite of tick-, mosquito-, and rodent-borne parasites through a continental-scale surveillance program. Here, we describe the sampling designs for these efforts, highlighting sampling priorities, field and analytical methods, and the data as well as archived samples to be made available to the research community. Insights generated by this sampling will advance current understanding of and ability to predict changes in infection and disease dynamics in novel, interdisciplinary, and collaborative ways.

  7. Constructing ecological interaction networks by correlation analysis: hints from community sampling

    Directory of Open Access Journals (Sweden)

    WenJun Zhang

    2011-09-01

    Full Text Available A set of methodology for constructing ecological interaction networks by correlation analysis of community sampling data was presented in this study. Nearly 30 data sets at different levels of taxa for different sampling seasons and locations were used to construct networks and find network properties. I defined the network constructed by Pearson linear correlation is the linear network, and the network constructed by quasi-linear correlation measure (e.g., Spearman correlation is the quasi-linear network. Two taxa with statistically significant linear or quasi-linear correlation are determined to interact. The quasi-linear network is more general than linear network.The results reveled that correlation distributions of Pearson linear correlation and partial linear correlation constructed networks are unimodal functions and most of them are short-head (mostly negative correlations and long-tailed (mostly positive correlations. Spearman correlation distributions are either long-head and short-tailed unimodal functions or monotonically increasing functions. It was found that both mean partial linear correlation and mean Pearson linear correlation were approximately 0. The proportion of positive (partial linear correlations declined significantly with the increase in taxa. The mean (partial linear correlation declined significantly with the increase of taxa. More than 90% of network interactions are positive interactions. The average connectance was 9.8% (9.3% for (partial linear correlation constructed network. The parameter λ in power low distribution (L(x=x-λ increased as the decline of taxon level (from functional group to species for the partial linear correlation constructed network. λ is in average 0.8 to 0.9. The number of (positive interactions increased with the number of taxa for both linear and partial linear correlations constructed networks. The addition of a taxon would result in an increase of 0.4 (0.3 interactions (positive

  8. Regional Localization with the Hawaii Island Infrasound Network

    Science.gov (United States)

    Perttu, A. B.; Garces, M. A.; Thelen, W. A.

    2013-12-01

    The Big Island of Hawaii is home to an extensive network of infrasound arrays, with additional arrays in Maui and Kauai. Four of the six Hawaii arrays are focused on Kilauea volcano. This project examines several methods for estimating source location, onset time, duration, and source energetics from regional infrasonic signals, with an emphasis on improving signal characterization. Diverse persistent natural and anthropogenic regional sources provide a data set for addressing localization with the Hawaii network. Explosions at the Pohakuloa Training Area, rock falls within the Halema'uma'u vent, and a repetitive unknown signal off the coast of Maui supply transient signals with known and unknown locations. In addition, Halema'uma'u and Pu'u O'o vents both produce infrasonic tremor with known locations. Well-constrained signal discrimination and characterization is essential for good location results. This paper presents progress in signal processing, feature extraction, and event association with standardized, self-similar, logarithmic time-frequency multiresolution algorithms. The Infrasonic Energy, Nth Octave (INFERNO) energy estimation suite of Garces (2013) is used in conjunction with the PMCC4 array processing algorithm to extract standardized signal features and parameters for improved regional association, localization, and source characterization.

  9. Resource redistribution in polydomous ant nest networks: local or global?

    Science.gov (United States)

    Franks, Daniel W.; Robinson, Elva J.H.

    2014-01-01

    An important problem facing organisms in a heterogeneous environment is how to redistribute resources to where they are required. This is particularly complex in social insect societies as resources have to be moved both from the environment into the nest and between individuals within the nest. Polydomous ant colonies are split between multiple spatially separated, but socially connected, nests. Whether, and how, resources are redistributed between nests in polydomous colonies is unknown. We analyzed the nest networks of the facultatively polydomous wood ant Formica lugubris. Our results indicate that resource redistribution in polydomous F. lugubris colonies is organized at the local level between neighboring nests and not at the colony level. We found that internest trails connecting nests that differed more in their amount of foraging were stronger than trails between nests with more equal foraging activity. This indicates that resources are being exchanged directly from nests with a foraging excess to nests that require resources. In contrast, we found no significant relationships between nest properties, such as size and amount of foraging, and network measures such as centrality and connectedness. This indicates an absence of a colony-level resource exchange. This is a clear example of a complex behavior emerging as a result of local interactions between parts of a system. PMID:25214755

  10. Local clustering in scale-free networks with hidden variables

    Science.gov (United States)

    van der Hofstad, Remco; Janssen, A. J. E. M.; van Leeuwaarden, Johan S. H.; Stegehuis, Clara

    2017-02-01

    We investigate the presence of triangles in a class of correlated random graphs in which hidden variables determine the pairwise connections between vertices. The class rules out self-loops and multiple edges. We focus on the regime where the hidden variables follow a power law with exponent τ ∈(2 ,3 ) , so that the degrees have infinite variance. The natural cutoff hc characterizes the largest degrees in the hidden variable models, and a structural cutoff hs introduces negative degree correlations (disassortative mixing) due to the infinite-variance degrees. We show that local clustering decreases with the hidden variable (or degree). We also determine how the average clustering coefficient C scales with the network size N , as a function of hs and hc. For scale-free networks with exponent 2 universality class at hand. We characterize the extremely slow decay of C when τ ≈2 and show that for τ =2.1 , say, clustering starts to vanish only for networks as large as N =109 .

  11. Characterizing emerging European stock markets through complex networks: From local properties to self-similar characteristics

    Science.gov (United States)

    Caraiani, Petre

    2012-07-01

    We investigate the properties of the returns of the main emerging stock markets from Europe by means of complex networks. We transform the series of daily returns into complex networks, and analyze the local properties of these networks with respect to degree distributions, clustering, or average line length. We further use the clustering coefficients as quantities describing the local structure of the network, and approach them by using multifractal analysis. We find evidence of scale-free networks and multifractality of clustering coefficients.

  12. An online database for informing ecological network models: http://kelpforest.ucsc.edu.

    Directory of Open Access Journals (Sweden)

    Rodrigo Beas-Luna

    Full Text Available Ecological network models and analyses are recognized as valuable tools for understanding the dynamics and resiliency of ecosystems, and for informing ecosystem-based approaches to management. However, few databases exist that can provide the life history, demographic and species interaction information necessary to parameterize ecological network models. Faced with the difficulty of synthesizing the information required to construct models for kelp forest ecosystems along the West Coast of North America, we developed an online database (http://kelpforest.ucsc.edu/ to facilitate the collation and dissemination of such information. Many of the database's attributes are novel yet the structure is applicable and adaptable to other ecosystem modeling efforts. Information for each taxonomic unit includes stage-specific life history, demography, and body-size allometries. Species interactions include trophic, competitive, facilitative, and parasitic forms. Each data entry is temporally and spatially explicit. The online data entry interface allows researchers anywhere to contribute and access information. Quality control is facilitated by attributing each entry to unique contributor identities and source citations. The database has proven useful as an archive of species and ecosystem-specific information in the development of several ecological network models, for informing management actions, and for education purposes (e.g., undergraduate and graduate training. To facilitate adaptation of the database by other researches for other ecosystems, the code and technical details on how to customize this database and apply it to other ecosystems are freely available and located at the following link (https://github.com/kelpforest-cameo/databaseui.

  13. No effect of seed source on multiple aspects of ecosystem functioning during ecological restoration: cultivars compared to local ecotypes of dominant grasses

    National Research Council Canada - National Science Library

    Baer, Sara G; Gibson, David J; Gustafson, Danny J; Benscoter, Allison M; Reed, Lewis K; Campbell, Ryan E; Klopf, Ryan P; Willand, Jason E; Wodika, Ben R

    2014-01-01

    Genetic principles underlie recommendations to use local seed, but a paucity of information exists on the genetic distinction and ecological consequences of using different seed sources in restorations...

  14. Design for mosquito abundance, diversity, and phenology sampling within the National Ecological Observatory Network

    Science.gov (United States)

    Hoekman, D.; Springer, Yuri P; Barker, C.M.; Barrera, R.; Blackmore, M.S.; Bradshaw, W.E.; Foley, D. H.; Ginsberg, Howard; Hayden, M. H.; Holzapfel, C. M.; Juliano, S. A.; Kramer, L. D.; LaDeau, S. L.; Livdahl, T. P.; Moore, C. G.; Nasci, R.S.; Reisen, W.K.; Savage, H. M.

    2016-01-01

    The National Ecological Observatory Network (NEON) intends to monitor mosquito populations across its broad geographical range of sites because of their prevalence in food webs, sensitivity to abiotic factors and relevance for human health. We describe the design of mosquito population sampling in the context of NEON’s long term continental scale monitoring program, emphasizing the sampling design schedule, priorities and collection methods. Freely available NEON data and associated field and laboratory samples, will increase our understanding of how mosquito abundance, demography, diversity and phenology are responding to land use and climate change.

  15. Ecology and evolution affect network structure in an intimate marine mutualism.

    Science.gov (United States)

    Thompson, Andrew R; Adam, Thomas C; Hultgren, Kristin M; Thacker, Christine E

    2013-08-01

    Elucidating patterns and causes of interaction among mutualistic species is a major focus of ecology, and recent meta-analyses of terrestrial networks show that network-level reciprocal specialization tends to be higher in intimate mutualisms than in nonintimate mutualisms. It is largely unknown, however, whether this pattern holds for and what factors affect specialization in marine mutualisms. Here we present the first analysis of network specialization ([Formula: see text]) for marine mutualistic networks. Specialization among eight Indo-Pacific networks of obligate mutualistic gobies and shrimps was indistinguishable from that among comparably intimate terrestrial mutualisms (ants-myrmecophytes) and higher than that among nonintimate ones (seed dispersers). Specialization was affected by variability in habitat use for both gobies and shrimps and by phylogenetic history for shrimps. Habitat use was phylogenetically conserved among shrimp, and thus effects of shrimp phylogeny on partner choice were mediated in part by habitat. By contrast, habitat use and pairing patterns in gobies were not related to phylogenetic history. This asymmetry appears to result from evolutionary constraints on partner use in shrimps and convergence among distantly related gobies to utilize burrows provided by multiple shrimp species. Results indicate that the evolution of mutualism is affected by life-history characteristics that transcend environments and that different factors constrain interactions in disparate ecosystems.

  16. A Game-Based Secure Localization Algorithm for Mobile Wireless Sensor Networks

    OpenAIRE

    Tianyue Bao; Jiangwen Wan; Kefu Yi; Qiang Zhang

    2015-01-01

    The issue of node localization is a fundamental problem in wireless sensor networks. Recently, the localization problem for mobile sensor networks in hostile environment has received significant attention. Due to the mobility of the sensor nodes, it is more challenging to achieve node localization in attacked sensor networks than in static ones. To address these challenges, the paper presents a novel game-based secure localization algorithm. The nodes’ strategy level can be indicated through ...

  17. Local Empathy provides Global Minimization of Congestion in Communication Networks

    CERN Document Server

    Meloni, Sandro

    2010-01-01

    We present a novel mechanism to avoid congestion in complex networks based on local knowledge of traffic conditions and the ability of routers to self-coordinate their dynamical behavior. In particular, routers make use of local information about traffic conditions to either reject or accept information packets from their neighbors. We show that when nodes are only aware of their own congestion state they self-organize into a hierarchical configuration that delays remarkably the onset of congestion although, leading to a sharp first-order like congestion transition. We also consider the case when nodes are aware of the congestion state of their neighbors. In this case, we show that empathy between nodes is strongly beneficial to the overall performance of the system and it is possible to achieve larger values for the critical load together with a smooth, second-order like, transition. Finally, we show how local empathy minimize the impact of congestion as much as global minimization. Therefore, here we presen...

  18. A Unified Multiscale Field/Network/Agent Based Modeling Framework for Human and Ecological Health Risk Analysis

    OpenAIRE

    2009-01-01

    A conceptual framework is presented for multiscale field/network/agent-based modeling to support human and ecological health risk assessments. This framework is based on the representation of environmental dynamics in terms of interacting networks, agents that move across different networks, fields representing spatiotemporal distributions of physical properties, rules governing constraints and interactions, and actors that make decisions affecting the state of the system. Different determini...

  19. Implementation of Network Community Profile using Local Spectral algorithm and its application in Community Networking

    Directory of Open Access Journals (Sweden)

    Vaibhav VPrakash

    2012-12-01

    Full Text Available The problem that is addressed here and being investigated is to empirically review the paper entitled"Empirical comparison of algorithms for network community detection" - Jure Leskovec, Kevin J Langand Michael W Mahoney”wherein we look at the characteristics and specific properties of varioussocial networks used in the public and private domain. The objective of the investigation is to understandcompletely the network community detection using Local Spectral and Metis+MQI algorithms and toanalyse how communities are created and ranked on specific metrics. Five communities have beencompared using the same heuristics of the established functions in the entitled paper and an inference isdrawn based on the graph generated by the same.

  20. Dispersal-induced destabilization of metapopulations and oscillatory Turing patterns in ecological networks

    Science.gov (United States)

    Hata, Shigefumi; Nakao, Hiroya; Mikhailov, Alexander S.

    2014-01-01

    As shown by Alan Turing in 1952, differential diffusion may destabilize uniform distributions of reacting species and lead to emergence of patterns. While stationary Turing patterns are broadly known, the oscillatory instability, leading to traveling waves in continuous media and sometimes called the wave bifurcation, remains less investigated. Here, we extend the original analysis by Turing to networks and apply it to ecological metapopulations with dispersal connections between habitats. Remarkably, the oscillatory Turing instability does not lead to wave patterns in networks, but to spontaneous development of heterogeneous oscillations and possible extinction of species. We find such oscillatory instabilities for all possible food webs with three predator or prey species, under various assumptions about the mobility of individual species and nonlinear interactions between them. Hence, the oscillatory Turing instability should be generic and must play a fundamental role in metapopulation dynamics, providing a common mechanism for dispersal-induced destabilization of ecosystems.

  1. Network modularity reveals critical scales for connectivity in ecology and evolution.

    Science.gov (United States)

    Fletcher, Robert J; Revell, Andre; Reichert, Brian E; Kitchens, Wiley M; Dixon, Jeremy D; Austin, James D

    2013-01-01

    For nearly a century, biologists have emphasized the profound importance of spatial scale for ecology, evolution and conservation. Nonetheless, objectively identifying critical scales has proven incredibly challenging. Here we extend new techniques from physics and social sciences that estimate modularity on networks to identify critical scales for movement and gene flow in animals. Using four species that vary widely in dispersal ability and include both mark-recapture and population genetic data, we identify significant modularity in three species, two of which cannot be explained by geographic distance alone. Importantly, the inclusion of modularity in connectivity and population viability assessments alters conclusions regarding patch importance to connectivity and suggests higher metapopulation viability than when ignoring this hidden spatial scale. We argue that network modularity reveals critical meso-scales that are probably common in populations, providing a powerful means of identifying fundamental scales for biology and for conservation strategies aimed at recovering imperilled species.

  2. Network modularity reveals critical scales for connectivity in ecology and evolution

    Science.gov (United States)

    Fletcher, Robert J.; Revell, Andre; Reichert, Brian E.; Kitchens, Wiley M.; Dixon, J.; Austin, James D.

    2013-01-01

    For nearly a century, biologists have emphasized the profound importance of spatial scale for ecology, evolution and conservation. Nonetheless, objectively identifying critical scales has proven incredibly challenging. Here we extend new techniques from physics and social sciences that estimate modularity on networks to identify critical scales for movement and gene flow in animals. Using four species that vary widely in dispersal ability and include both mark-recapture and population genetic data, we identify significant modularity in three species, two of which cannot be explained by geographic distance alone. Importantly, the inclusion of modularity in connectivity and population viability assessments alters conclusions regarding patch importance to connectivity and suggests higher metapopulation viability than when ignoring this hidden spatial scale. We argue that network modularity reveals critical meso-scales that are probably common in populations, providing a powerful means of identifying fundamental scales for biology and for conservation strategies aimed at recovering imperilled species.

  3. Informatics technology mimics ecology: dense, mutualistic collaboration networks are associated with higher publication rates.

    Science.gov (United States)

    Sorani, Marco D

    2012-01-01

    Information technology (IT) adoption enables biomedical research. Publications are an accepted measure of research output, and network models can describe the collaborative nature of publication. In particular, ecological networks can serve as analogies for publication and technology adoption. We constructed network models of adoption of bioinformatics programming languages and health IT (HIT) from the literature.We selected seven programming languages and four types of HIT. We performed PubMed searches to identify publications since 2001. We calculated summary statistics and analyzed spatiotemporal relationships. Then, we assessed ecological models of specialization, cooperativity, competition, evolution, biodiversity, and stability associated with publications.Adoption of HIT has been variable, while scripting languages have experienced rapid adoption. Hospital systems had the largest HIT research corpus, while Perl had the largest language corpus. Scripting languages represented the largest connected network components. The relationship between edges and nodes was linear, though Bioconductor had more edges than expected and Perl had fewer. Spatiotemporal relationships were weak. Most languages shared a bioinformatics specialization and appeared mutualistic or competitive. HIT specializations varied. Specialization was highest for Bioconductor and radiology systems. Specialization and cooperativity were positively correlated among languages but negatively correlated among HIT. Rates of language evolution were similar. Biodiversity among languages grew in the first half of the decade and stabilized, while diversity among HIT was variable but flat. Compared with publications in 2001, correlation with publications one year later was positive while correlation after ten years was weak and negative.Adoption of new technologies can be unpredictable. Spatiotemporal relationships facilitate adoption but are not sufficient. As with ecosystems, dense, mutualistic

  4. Informatics technology mimics ecology: dense, mutualistic collaboration networks are associated with higher publication rates.

    Directory of Open Access Journals (Sweden)

    Marco D Sorani

    Full Text Available Information technology (IT adoption enables biomedical research. Publications are an accepted measure of research output, and network models can describe the collaborative nature of publication. In particular, ecological networks can serve as analogies for publication and technology adoption. We constructed network models of adoption of bioinformatics programming languages and health IT (HIT from the literature.We selected seven programming languages and four types of HIT. We performed PubMed searches to identify publications since 2001. We calculated summary statistics and analyzed spatiotemporal relationships. Then, we assessed ecological models of specialization, cooperativity, competition, evolution, biodiversity, and stability associated with publications.Adoption of HIT has been variable, while scripting languages have experienced rapid adoption. Hospital systems had the largest HIT research corpus, while Perl had the largest language corpus. Scripting languages represented the largest connected network components. The relationship between edges and nodes was linear, though Bioconductor had more edges than expected and Perl had fewer. Spatiotemporal relationships were weak. Most languages shared a bioinformatics specialization and appeared mutualistic or competitive. HIT specializations varied. Specialization was highest for Bioconductor and radiology systems. Specialization and cooperativity were positively correlated among languages but negatively correlated among HIT. Rates of language evolution were similar. Biodiversity among languages grew in the first half of the decade and stabilized, while diversity among HIT was variable but flat. Compared with publications in 2001, correlation with publications one year later was positive while correlation after ten years was weak and negative.Adoption of new technologies can be unpredictable. Spatiotemporal relationships facilitate adoption but are not sufficient. As with ecosystems, dense

  5. Rethinking Local Governance: Hierarchies and Networks in Mexican Cities

    Directory of Open Access Journals (Sweden)

    Francisco Porras

    2007-10-01

    Full Text Available In recent years, the literature of governance has  gained relevance in public administration studies.  One of its main contributions has been to propose  that the use of networks in policy processes, instead of hierarchies, has modified our understanding of contemporary government. Governance  literature has been produced mainly in AngloSaxon countries; nevertheless, this article argues  that it has some value as a tool to explain present  dynamisms in Mexican municipalities. Local  networks have become more important to policymaking in Mexico and, as a result, nongovernmental actors are now more influential in  some policy sectors. The article proposes that this  partial shift from government to governance has  increased bureaucratic fragmentation, the blurredness between the public and private spheres, and  non-governmental self-organization. Defined in  these broad categories, governance theoretical  frameworks are useful to understand Mexican  cities. Resumen:  Reconsiderando la gobernanza local: Jerarquías y redes en ciudades mexicanasEn los últimos años, el enfoque teórico de la gobernanza (governance ha ganado terreno en los estudios de la administración pública. La gobernanza  propone básicamente que al introducir redes (en  lugar de jerarquías en los procesos de políticas  públicas, se modifica el significado tradicional de lo  que es el gobierno. Aunque la literatura de la gobernanza se ha generado sobre todo en países anglosajones, este artículo sostiene que posee un  cierto valor para analizar los gobiernos locales de  México. Las redes ahora son más importantes en  los procesos de políticas públicas locales y, por  consiguiente, los actores no-gubernamentales son  más influyentes en algunos sectores. El artículo  propone que este cambio parcial del gobierno a la  gobernanza ha incrementado la fragmentación  burocrática, la borrosidad entre lo público y lo  privado, y la auto

  6. Local food in European supply chains: reconnection and electronic networks

    Directory of Open Access Journals (Sweden)

    Georgina Holt

    2007-04-01

    Full Text Available Après une présentation du marché des produits locaux/localisés en Grande Bretagne, ainsi qu’une définition du concept en fonction des circuits de distribution courts, de l’agriculture biologique et du commerce équitable, cet article se fonde sur des études de cas, issus de projets de recherche européens, pour identifier des différents types de réseaux concernés par les concept de produit locaux durables. Les habitudes historiques concernant l’achat des produits alimentaires jouent ici un rôle central et l’article observe l’équilibre entre les composants historiques, sociaux et environnementaux des produits locaux/localisés. A partir de ces terrains de recherche et de ces expériences il s’est avéré possible de déterminer différentes compréhensions de « produits locaux » en relation avec le concept de « distance alimentaire/ food miles ». En se référant à six cas donnés, cet article souligne l’importance des systèmes localisés en matière de durabilité alimentaire, et met en valeur le poids des qualités humaines et sociales dans la balance commerciale.After giving an overview of the market for local food in the UK, as well as a definition of the concept in relation to short supply chains, organic agriculture and fair trade, the article draws on cases encountered through EC-funded research and networking to identify different types of network concerned with the concept of sustaining local food. Historical uses of shopping habits play here a central role and the article observes the balance between historical, social and environmental components of local food. From these researches and experiences, it has been possible to demonstrate a range of understandings in relation to the concept of ‘food miles’. With reference to six cases, the article underlines the importance of local food systems within food sustainability, and highlights the weight of human and social qualities in the market balance.

  7. Local Scale Transformations on the Lattice with Tensor Network Renormalization

    Science.gov (United States)

    Evenbly, G.; Vidal, G.

    2016-01-01

    Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.

  8. RH+: A Hybrid Localization Algorithm for Wireless Sensor Networks

    Science.gov (United States)

    Basaran, Can; Baydere, Sebnem; Kucuk, Gurhan

    Today, localization of nodes in Wireless Sensor Networks (WSNs) is a challenging problem. Especially, it is almost impossible to guarantee that one algorithm giving optimal results for one topology will give optimal results for any other random topology. In this study, we propose a centralized, range- and anchor-based, hybrid algorithm called RH+ that aims to combine the powerful features of two orthogonal techniques: Classical Multi-Dimensional Scaling (CMDS) and Particle Spring Optimization (PSO). As a result, we find that our hybrid approach gives a fast-converging solution which is resilient to range-errors and very robust to topology changes. Across all topologies we studied, the average estimation error is less than 0.5m. when the average node density is 10 and only 2.5% of the nodes are beacons.

  9. Local Scale Transformations on the Lattice with Tensor Network Renormalization.

    Science.gov (United States)

    Evenbly, G; Vidal, G

    2016-01-29

    Consider the partition function of a classical system in two spatial dimensions, or the Euclidean path integral of a quantum system in two space-time dimensions, both on a lattice. We show that the tensor network renormalization algorithm [G. Evenbly and G. Vidal Phys. Rev. Lett. 115, 180405 (2015)] can be used to implement local scale transformations on these objects, namely, a lattice version of conformal maps. Specifically, we explain how to implement the lattice equivalent of the logarithmic conformal map that transforms the Euclidean plane into a cylinder. As an application, and with the 2D critical Ising model as a concrete example, we use this map to build a lattice version of the scaling operators of the underlying conformal field theory, from which one can extract their scaling dimensions and operator product expansion coefficients.

  10. Explicit Sensor Network Localization using Semidefinite Representations and Facial Reductions

    CERN Document Server

    Krislock, Nathan

    2010-01-01

    The sensor network localization, SNL, problem in embedding dimension r, consists of locating the positions of wireless sensors, given only the distances between sensors that are within radio range and the positions of a subset of the sensors (called anchors). Current solution techniques relax this problem to a weighted, nearest, (positive) semidefinite programming, SDP, completion problem, by using the linear mapping between Euclidean distance matrices, EDM, and semidefinite matrices. The resulting SDP is solved using primal-dual interior point solvers, yielding an expensive and inexact solution. This relaxation is highly degenerate in the sense that the feasible set is restricted to a low dimensional face of the SDP cone, implying that the Slater constraint qualification fails. Cliques in the graph of the SNL problem give rise to this degeneracy in the SDP relaxation. In this paper, we take advantage of the absence of the Slater constraint qualification and derive a technique for the SNL problem, with exact ...

  11. Assessment of the capacity of the national ecological network elements for road construction and operation

    Directory of Open Access Journals (Sweden)

    Kicošev Vesna

    2014-01-01

    Full Text Available Road construction and usage have a wide range of direct and indirect negative effects on protected areas. The impact of state roads on protected areas in Vojvodina was reviewed in this article, based on the orientation values of habitat loss and secondary negative effects originating from traffic functioning. Results of the assessment indicate that the use of existing roads constructed on habitats within the national ecological network exceeded the capacity of individual PA-protected areas (e.g., in case of Straža Natural Monument. Recorded capacity overflow on other PAs occurs solely as a consequence of overlapping between protected areas and areas of influence of roads routed along the borders of protected areas (which is the case with Slano Kopovo Special Nature Reserve and Selevenjske pustare Special Nature Reserve. The aim of this article is to show that even with the smallest values of the parameters related to the width of roads and critical distance from the habitat, the vulnerability of certain core areas of the national ecological network is evident.

  12. Estimation of local rainfall erosivity using artificial neural network

    Directory of Open Access Journals (Sweden)

    Paulo Tarso Sanches Oliveira

    2011-08-01

    Full Text Available The information retrieval of local values of rainfall erosivity is essential for soil loss estimation with the Universal Soil Loss Equation (USLE, and thus is very useful in soil and water conservation planning. In this manner, the objective of this study was to develop an Artificial Neural Network (ANN with the capacity of estimating, with satisfactory accuracy, the rainfall erosivity in any location of the Mato Grosso do Sul state. We used data from rain erosivity, latitude, longitude, altitude of pluviometric and pluviographic stations located in the state to train and test an ANN. After training with various network configurations, we selected the best performance and higher coefficient of determination calculated on the basis of data erosivity of the sample test and the values estimated by ANN. In evaluating the results, the confidence and the agreement indices were used in addition to the coefficient of determination. It was found that it is possible to estimate the rainfall erosivity for any location in the state of Mato Grosso do Sul, in a reliable way, using only data of geographical coordinates and altitude.

  13. Locality-Driven Parallel Static Analysis for Power Delivery Networks

    KAUST Repository

    Zeng, Zhiyu

    2011-06-01

    Large VLSI on-chip Power Delivery Networks (PDNs) are challenging to analyze due to the sheer network complexity. In this article, a novel parallel partitioning-based PDN analysis approach is presented. We use the boundary circuit responses of each partition to divide the full grid simulation problem into a set of independent subgrid simulation problems. Instead of solving exact boundary circuit responses, a more efficient scheme is proposed to provide near-exact approximation to the boundary circuit responses by exploiting the spatial locality of the flip-chip-type power grids. This scheme is also used in a block-based iterative error reduction process to achieve fast convergence. Detailed computational cost analysis and performance modeling is carried out to determine the optimal (or near-optimal) number of partitions for parallel implementation. Through the analysis of several large power grids, the proposed approach is shown to have excellent parallel efficiency, fast convergence, and favorable scalability. Our approach can solve a 16-million-node power grid in 18 seconds on an IBM p5-575 processing node with 16 Power5+ processors, which is 18.8X faster than a state-of-the-art direct solver. © 2011 ACM.

  14. The plant phenology monitoring design for the National Ecological Observatory Network

    Science.gov (United States)

    Elmendorf, Sarah C; Jones, Katherine D; Cook, Benjamin I.; Diez, Jeffrey M.; Enquist, Carolyn A.F.; Hufft, Rebecca A.; Jones, Matthew O.; Mazer, Susan J.; Miller-Rushing, Abraham J.; Moore, David J. P.; Schwartz, Mark D.; Weltzin, Jake

    2016-01-01

    Phenology is an integrative science that comprises the study of recurring biological activities or events. In an era of rapidly changing climate, the relationship between the timing of those events and environmental cues such as temperature, snowmelt, water availability or day length are of particular interest. This article provides an overview of the plant phenology sampling which will be conducted by the U.S. National Ecological Observatory Network NEON, the resulting data, and the rationale behind the design. Trained technicians will conduct regular in situ observations of plant phenology at all terrestrial NEON sites for the 30-year life of the observatory. Standardized and coordinated data across the network of sites can be used to quantify the direction and magnitude of the relationships between phenology and environmental forcings, as well as the degree to which these relationships vary among sites, among species, among phenophases, and through time. Vegetation at NEON sites will also be monitored with tower-based cameras, satellite remote sensing and annual high-resolution airborne remote sensing. Ground-based measurements can be used to calibrate and improve satellite-derived phenometrics. NEON’s phenology monitoring design is complementary to existing phenology research efforts and citizen science initiatives throughout the world and will produce interoperable data. By collocating plant phenology observations with a suite of additional meteorological, biophysical and ecological measurements (e.g., climate, carbon flux, plant productivity, population dynamics of consumers) at 47 terrestrial sites, the NEON design will enable continentalscale inference about the status, trends, causes and ecological consequences of phenological change.

  15. The Plant Phenology Monitoring Design for the National Ecological Observatory Network

    Science.gov (United States)

    Elmendorf, Sarah C.; Jones, Katherine D.; Cook, Benjamin I.; Diez, Jeffrey M.; Enquist, Carolyn A. F.; Hufft, Rebecca A.; Jones, Matthew O.; Mazer, Susan J.; Miller-Rushing, Abraham J.; Moore, David J. P.; Schwartz, Mark D.; Weltzin, Jake F.

    2016-01-01

    Phenology is an integrative science that comprises the study of recurring biological activities or events. In an era of rapidly changing climate, the relationship between the timing of those events and environmental cues such as temperature, snowmelt, water availability, or day length are of particular interest. This article provides an overview of the observer-based plant phenology sampling conducted by the U.S. National Ecological Observatory Network (NEON), the resulting data, and the rationale behind the design. Trained technicians will conduct regular in situ observations of plant phenology at all terrestrial NEON sites for the 30-yr life of the observatory. Standardized and coordinated data across the network of sites can be used to quantify the direction and magnitude of the relationships between phenology and environmental forcings, as well as the degree to which these relationships vary among sites, among species, among phenophases, and through time. Vegetation at NEON sites will also be monitored with tower-based cameras, satellite remote sensing, and annual high-resolution airborne remote sensing. Ground-based measurements can be used to calibrate and improve satellite-derived phenometrics. NEON's phenology monitoring design is complementary to existing phenology research efforts and citizen science initiatives throughout the world and will produce interoperable data. By collocating plant phenology observations with a suite of additional meteorological, biophysical, and ecological measurements (e.g., climate, carbon flux, plant productivity, population dynamics of consumers) at 47 terrestrial sites, the NEON design will enable continental-scale inference about the status, trends, causes, and ecological consequences of phenological change.

  16. Ecological network analysis for economic systems: growth and development and implications for sustainable development.

    Science.gov (United States)

    Huang, Jiali; Ulanowicz, Robert E

    2014-01-01

    The quantification of growth and development is an important issue in economics, because these phenomena are closely related to sustainability. We address growth and development from a network perspective in which economic systems are represented as flow networks and analyzed using ecological network analysis (ENA). The Beijing economic system is used as a case study and 11 input-output (I-O) tables for 1985-2010 are converted into currency networks. ENA is used to calculate system-level indices to quantify the growth and development of Beijing. The contributions of each direct flow toward growth and development in 2010 are calculated and their implications for sustainable development are discussed. The results show that during 1985-2010, growth was the main attribute of the Beijing economic system. Although the system grew exponentially, its development fluctuated within only a small range. The results suggest that system ascendency should be increased in order to favor more sustainable development. Ascendency can be augmented in two ways: (1) strengthen those pathways with positive contributions to increasing ascendency and (2) weaken those with negative effects.

  17. Application of local area networks to accelerator control systems at the Stanford Linear Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Fox, J.D.; Linstadt, E.; Melen, R.

    1983-03-01

    The history and current status of SLAC's SDLC networks for distributed accelerator control systems are discussed. These local area networks have been used for instrumentation and control of the linear accelerator. Network topologies, protocols, physical links, and logical interconnections are discussed for specific applications in distributed data acquisition and control system, computer networks and accelerator operations.

  18. Damage Detection and Localization from Dense Network of Strain Sensors

    Directory of Open Access Journals (Sweden)

    Simon Laflamme

    2016-01-01

    Full Text Available Structural health monitoring of large systems is a complex engineering task due to important practical issues. When dealing with large structures, damage diagnosis, localization, and prognosis necessitate a large number of sensors, which is a nontrivial task due to the lack of scalability of traditional sensing technologies. In order to address this challenge, the authors have recently proposed a novel sensing solution consisting of a low-cost soft elastomeric capacitor that transduces surface strains into measurable changes in capacitance. This paper demonstrates the potential of this technology for damage detection, localization, and prognosis when utilized in dense network configurations over large surfaces. A wind turbine blade is adopted as a case study, and numerical simulations demonstrate the effectiveness of a data-driven algorithm relying on distributed strain data in evidencing the presence and location of damage, and sequentially ranking its severity. Numerical results further show that the soft elastomeric capacitor may outperform traditional strain sensors in damage identification as it provides additive strain measurements without any preferential direction. Finally, simulation with reconstruction of measurements from missing or malfunctioning sensors using the concepts of virtual sensors and Kriging demonstrates the robustness of the proposed condition assessment methodology for sparser or malfunctioning grids.

  19. Interference in the tundra predator guild studied using local ecological knowledge.

    Science.gov (United States)

    Ehrich, Dorothee; Strømeng, Marita A; Killengreen, Siw T

    2016-04-01

    The decline or recolonization of apex predators such as wolves and lynx, often driven by management decisions, and the expansion of smaller generalist predators such as red foxes, can have important ecosystem impacts. The mesopredator release hypothesis proposes that apex predators control medium-sized predator populations through competition and/or intraguild predation. The decline of apex predators thus leads to an increase in mesopredators, possibly with a negative impact on prey populations. Information about the abundance of mammalian tundra predators, wolf (Canis lupus), wolverine (Gulo gulo), lynx (Lynx lynx), red fox (Vulpes vulpes) and arctic fox (Vulpes lagopus) was collected from local active outdoors people during semi-structured interviews in 14 low arctic or sub-arctic settlements in western Eurasia. The perceived abundance of red fox decreased with higher wolf abundance and in more arctic areas, but the negative effect of wolves decreased in more arctic and therefore less productive ecosystems. The perceived abundance of arctic fox increased towards the arctic and in areas with colder winters. Although there was a negative correlation between the two fox species, red fox was not included in the model for perceived arctic fox abundance, which received most support. Our results support the mesopredator release hypothesis regarding the expansion of red foxes in subarctic areas and indicate that top-down control by apex predators is weaker in less productive and more arctic ecosystems. We showed that local ecological knowledge is a valuable source of information about large-scale processes, which are difficult to study through direct biological investigations.

  20. Local food environment and fruit and vegetable consumption: An ecological study.

    Science.gov (United States)

    Menezes, Mariana Carvalho; Costa, Bruna Vieirade Lima; Oliveira, Cláudia Di Lorenzo; Lopes, Aline Cristine Souza

    2017-03-01

    Ecological studies are essential for understanding the environment-diet relationship. The purpose of this study was to describe environmental conditions and their relationship with fruit and vegetable (FV) consumption among Brazilian public health service users in the city of Belo Horizonte. We evaluated food stores contained within 1600 m buffer zones at 18 Health Academy Programme sites, from 2013 to 2014. Variables at the community (density, proximity and type) and the consumer (sectional location of FV; availability, quality, variety, price and advertising of FV and ultra-processed foods) nutrition environment were measured by direct observation, while aggregate data from users (income and FV consumption) were obtained by interview. Data were analysed using the Kernel intensity estimator, average nearest neighbour value and Local Moran's Index for local spatial autocorrelation. We interviewed 3414 users and analysed 336 food stores. Major geographical variations in the FV consumption were identified. Average consumption was higher (site 2A: 410.5 ± 185.7 g vs. site 4B: 311.2 ± 159.9 g) in neighbourhoods with higher income and concentration of food stores, and better index of access to healthy foods. Sites with poor FV consumption had the most stores with poor access to healthy foods (index in the first tertile, ≤ 10). In conclusion, negative characteristics of the food environment, as seen in the present study, may contribute to low FV consumption, suggesting the need for the development and consolidation of public policies aimed at creating healthy environments through built environment interventions that increase access to and consumption of healthy foods like FV.

  1. Local food environment and fruit and vegetable consumption: An ecological study

    Directory of Open Access Journals (Sweden)

    Mariana Carvalho Menezes

    2017-03-01

    Full Text Available Ecological studies are essential for understanding the environment-diet relationship. The purpose of this study was to describe environmental conditions and their relationship with fruit and vegetable (FV consumption among Brazilian public health service users in the city of Belo Horizonte. We evaluated food stores contained within 1600 m buffer zones at 18 Health Academy Programme sites, from 2013 to 2014. Variables at the community (density, proximity and type and the consumer (sectional location of FV; availability, quality, variety, price and advertising of FV and ultra-processed foods nutrition environment were measured by direct observation, while aggregate data from users (income and FV consumption were obtained by interview. Data were analysed using the Kernel intensity estimator, average nearest neighbour value and Local Moran's Index for local spatial autocorrelation. We interviewed 3414 users and analysed 336 food stores. Major geographical variations in the FV consumption were identified. Average consumption was higher (site 2A: 410.5 ± 185.7 g vs. site 4B: 311.2 ± 159.9 g in neighbourhoods with higher income and concentration of food stores, and better index of access to healthy foods. Sites with poor FV consumption had the most stores with poor access to healthy foods (index in the first tertile, ≤10. In conclusion, negative characteristics of the food environment, as seen in the present study, may contribute to low FV consumption, suggesting the need for the development and consolidation of public policies aimed at creating healthy environments through built environment interventions that increase access to and consumption of healthy foods like FV.

  2. Achieving ecological restoration by working with local people: a Chinese scholar seeks win-win paths

    Directory of Open Access Journals (Sweden)

    Heran Zheng

    2014-09-01

    Full Text Available Environmental degradation and poverty are linked, and this means that conservation and poverty reduction must be tackled together. However, finding a successful integrated strategy has been an elusive goal. We describe the career of a Chinese scholar, Shixiong Cao, whose persistent efforts to find and follow win-win paths have led to ecological restoration accompanied by long-term benefits for local residents. Cao's story illustrates how development that combines environmental and economic perspectives can both help people to escape the poverty trap and restore degraded environments. His experience demonstrates that when environmental managers find solutions that can mitigate or eliminate poverty through the development of green enterprises, they can combine them with environmental restoration efforts to produce long-term sustainable solutions. In this paper, we share Cao's 28 years of experience because we believe that his scientific and practical spirit, and his belief that it is necessary to work directly with the people affected by environmental projects, will inspire other scholars and practitioners to achieve similar successes.

  3. Local Area Networks--The ENFI Project (Writing on the College Campus).

    Science.gov (United States)

    Stine, Linda

    1989-01-01

    Describes Electronic Networks for Interaction (ENFI), a local area network project developed at Gallaudet University to empower students with hearing impairments. Notes that this project can be adapted easily for use with traditional students. (MM)

  4. Dense Local Seismic Network at Villarrica Volcano (Southern Chile)

    Science.gov (United States)

    Mora-Stock, C.; Thorwart, M.; Dzieran, L.; Rabbel, W.

    2013-12-01

    Villarrica volcano is one of the most active volcanoes in the Southern Andes. It has been presenting constant fumarole activity and seismicity since its last eruption in 1984-85. A local network was installed at Villarrica volcano (Southern Chile) during the first two weeks of March, 2012. In total, 75 DSS-Cube short-period stations (30 3-Component, 45 1-Component) were deployed at and around the volcano area, covering approx. 63 km x 55 km. The average station spacing is 1.5 km for stations inside the perimeter of the volcanic edifice, and 5km outside this perimeter. The network recorded ca. 94 volcano tectonic (VT) events located SSW, SSE and North of the crater, with clear P- and S-wave arrivals. Many others, ca.73 events, could be classified as 'hybrid' events (HB), which present high frequencies at the beginning of the signal, and a sharp and notorious S-wave at the crater stations, but a strong scattering, lower frequency content, and elongated coda on the stations along the volcanic edifice. This strong scattering effect is probably caused by the heterogeneous ash layers on the edifice structure. Few long period events (LP), with main frequencies between 2-4 Hz, were observed. From the tectonic regional events, three sets of events can be distinguished. One coming from the southern end of the focal plane of the Maule earthquake (2010), with S-P wave travel time difference of ca. 30 s or more. Another closer group with S-P wave travel time difference between 10 s and 20 s, and the last group with S-P wave travel time difference of 10 s or less. A cross-correlation analysis to the travel times of the regional events and a teleseismic event from Argentina was applied in order to determine the average velocity structure of the volcano, and obtained an average P-wave velocity of 3.6 km/s for the volcanic edifice inside a radius of 6.5 km, and 4.1 km/s for the surrounding area outside this radius. This model serves as a starting point for local earthquake

  5. [Systemic approach to ecologic safety at objects with radiation jeopardy, involved into localization of low and medium radioactive waste].

    Science.gov (United States)

    Veselov, E I

    2011-01-01

    The article deals with specifying systemic approach to ecologic safety of objects with radiation jeopardy. The authors presented stages of work and algorithm of decisions on preserving reliability of storage for radiation jeopardy waste. Findings are that providing ecologic safety can cover 3 approaches: complete exemption of radiation jeopardy waste, removal of more dangerous waste from present buildings and increasing reliability of prolonged localization of radiation jeopardy waste at the initial place. The systemic approach presented could be realized at various radiation jeopardy objects.

  6. How Do Student Teachers' Beliefs Change When the New Ecological Paradigm Is Grounded into a Local Context Related to the Balinese Subak Landscape Heritage?

    Science.gov (United States)

    Putu, Surata Sang

    2017-01-01

    The objective of this research is to assess global and local environmental views of student teachers using the new ecological paradigm (NEP) and the local ecological paradigm (LEP) scales. Ninety-two undergraduate students from Universitas Mahasaraswati Denpasar, Indonesia were requested to rate and write individual arguments to each item of the…

  7. Design and implementation of interface units for high speed fiber optics local area networks and broadband integrated services digital networks

    Science.gov (United States)

    Tobagi, Fouad A.; Dalgic, Ismail; Pang, Joseph

    1990-01-01

    The design and implementation of interface units for high speed Fiber Optic Local Area Networks and Broadband Integrated Services Digital Networks are discussed. During the last years, a number of network adapters that are designed to support high speed communications have emerged. This approach to the design of a high speed network interface unit was to implement package processing functions in hardware, using VLSI technology. The VLSI hardware implementation of a buffer management unit, which is required in such architectures, is described.

  8. Cooperative and Distributed Localization for Wireless Sensor Networks in Multipath Environments

    CERN Document Server

    Leng, Mei; Quek, Tony Q S

    2011-01-01

    We consider the problem of sensor localization in a wireless network in a multipath environment, where time and angle of arrival information are available at each sensor. We propose a distributed algorithm based on belief propagation, which allows sensors to cooperatively self-localize with respect to one single anchor in a multihop network. The algorithm has low overhead and is scalable. Simulations show that although the network is loopy, the proposed algorithm converges, and achieves good localization accuracy.

  9. Assessing Local Communities’ Willingness to Pay for River Network Protection: A Contingent Valuation Study of Shanghai, China

    Directory of Open Access Journals (Sweden)

    Yu Jiang

    2012-10-01

    Full Text Available River networks have experienced serious degradation because of rapid urbanization and population growth in developing countries such as China, and the protection of these networks requires the integration of evaluation with ecology and economics. In this study, a structured questionnaire survey of local residents in Shanghai (China was conducted in urban and suburban areas. The study examined residents’ awareness of the value of the river network, sought their attitude toward the current status, and employed a logistic regression analysis based on the contingent valuation method (CVM to calculate the total benefit and explain the socioeconomic factors influencing the residents’ willingness to pay (WTP. The results suggested that residents in Shanghai had a high degree of recognition of river network value but a low degree of satisfaction with the government’s actions and the current situation. The study also illustrated that the majority of respondents were willing to pay for river network protection. The mean WTP was 226.44 RMB per household per year. The number of years lived in Shanghai, the distance from the home to the nearest river, and the amount of the bid were important factors that influenced the respondents’ WTP. Suggestions for comprehensive management were proposed for the use of policy makers in river network conservation.

  10. MOBILITY AIDED LOCALIZATION OF WIRELESS SENSOR NETWORKS WITH INACCURATE RANGE MEASUREMENTS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This paper studies the relationship between mobility, navigation and localization in the context of wireless sensor networks with mobile beacons. It is observed that mobility can aid in network node localization and that once localized, the network nodes can localize and track a mobile object and guide its navigation.A distributed kernel-based algorithm is proposed that enables the nodes to establish confident position estimates in the presence of ranging inaccuracies. The proposed approach features robustness with respect to range measurement inaccuracies, low complexity and distributed implementation, using only local information.Simulation validates our approach viable.

  11. Communication issues in determining departmental local area networks requirements

    Science.gov (United States)

    Dabipi, I. K.; Donaldson, A.; Anderson, James A.

    1995-07-01

    One of the major issues when configuring networks is about the way in which the decision on what kind of a network to install is made. The Electrical Engineering Department at Southern University has recently gone through this process. This paper addresses the related network design issues as a class project simulation of the different network designs. The simulation details the network simulation and the network connectivity issues. A comparison of the various designs is presented and the reason for the choice of the final configuration is also given.

  12. Local versus Generalized Phenotypes in Two Sympatric Aurelia Species: Understanding Jellyfish Ecology Using Genetics and Morphometrics.

    Science.gov (United States)

    Chiaverano, Luciano M; Bayha, Keith W; Graham, William M

    2016-01-01

    For individuals living in environmentally heterogeneous environments, a key component for adaptation and persistence is the extent of phenotypic differentiation in response to local environmental conditions. In order to determine the extent of environmentally induced morphological variation in a natural population distributed along environmental gradients, it is necessary to account for potential genetic differences contributing to morphological differentiation. In this study, we set out to quantify geographic morphological variation in the moon jellyfish Aurelia exposed at the extremes of a latitudinal environmental gradient in the Gulf of Mexico (GoM). We used morphological data based on 28 characters, and genetic data taken from mitochondrial cytochrome oxidase I (COI) and nuclear internal transcribed spacer 1 (ITS-1). Molecular analyses revealed the presence of two genetically distinct species of Aurelia co-occurring in the GoM: Aurelia sp. 9 and Aurelia c.f. sp. 2, named for its divergence from (for COI) and similarity to (for ITS-1) Aurelia sp. 2 (Brazil). Neither species exhibited significant population genetic structure between the Northern and the Southeastern Gulf of Mexico; however, they differed greatly in the degree of geographic morphological variation. The morphology of Aurelia sp. 9 exhibited ecophenotypic plasticity and varied significantly between locations, while morphology of Aurelia c.f. sp. 2 was geographically invariant (i.e., canalized). The plastic, generalist medusae of Aurelia sp. 9 are likely able to produce environmentally-induced, "optimal" phenotypes that confer high relative fitness in different environments. In contrast, the non-plastic generalist individuals of Aurelia c.f. sp. 2 likely produce environmentally-independent phenotypes that provide the highest fitness across environments. These findings suggest the two Aurelia lineages co-occurring in the GoM were likely exposed to different past environmental conditions (i

  13. Local versus Generalized Phenotypes in Two Sympatric Aurelia Species: Understanding Jellyfish Ecology Using Genetics and Morphometrics.

    Directory of Open Access Journals (Sweden)

    Luciano M Chiaverano

    Full Text Available For individuals living in environmentally heterogeneous environments, a key component for adaptation and persistence is the extent of phenotypic differentiation in response to local environmental conditions. In order to determine the extent of environmentally induced morphological variation in a natural population distributed along environmental gradients, it is necessary to account for potential genetic differences contributing to morphological differentiation. In this study, we set out to quantify geographic morphological variation in the moon jellyfish Aurelia exposed at the extremes of a latitudinal environmental gradient in the Gulf of Mexico (GoM. We used morphological data based on 28 characters, and genetic data taken from mitochondrial cytochrome oxidase I (COI and nuclear internal transcribed spacer 1 (ITS-1. Molecular analyses revealed the presence of two genetically distinct species of Aurelia co-occurring in the GoM: Aurelia sp. 9 and Aurelia c.f. sp. 2, named for its divergence from (for COI and similarity to (for ITS-1 Aurelia sp. 2 (Brazil. Neither species exhibited significant population genetic structure between the Northern and the Southeastern Gulf of Mexico; however, they differed greatly in the degree of geographic morphological variation. The morphology of Aurelia sp. 9 exhibited ecophenotypic plasticity and varied significantly between locations, while morphology of Aurelia c.f. sp. 2 was geographically invariant (i.e., canalized. The plastic, generalist medusae of Aurelia sp. 9 are likely able to produce environmentally-induced, "optimal" phenotypes that confer high relative fitness in different environments. In contrast, the non-plastic generalist individuals of Aurelia c.f. sp. 2 likely produce environmentally-independent phenotypes that provide the highest fitness across environments. These findings suggest the two Aurelia lineages co-occurring in the GoM were likely exposed to different past environmental conditions

  14. Inclusive Protected Area Management in the Amazon: The Importance of Social Networks over Ecological Knowledge

    Directory of Open Access Journals (Sweden)

    Roger Strand

    2012-11-01

    Full Text Available In the Amacayacu National Park in Colombia, which partially overlaps with Indigenous territories, several elements of an inclusive protected area management model have been implemented since the 1990s. In particular, a dialogue between scientific researchers, indigenous people and park staff has been promoted for the co-production of biological and cultural knowledge for decision-making. This paper, based on a four-year ethnographic study of the park, shows how knowledge products about different components of the socio-ecosystem neither were efficiently obtained nor were of much importance in park management activities. Rather, the knowledge pertinent to park staff in planning and management is the know-how required for the maintenance and mobilization of multi-scale social-ecological networks. We argue that the dominant models for protected area management—both top-down and inclusive models—underestimate the sociopolitical realm in which research is expected to take place, over-emphasize ecological knowledge as necessary for management and hold a too strong belief in decision-making as a rational, organized response to diagnosis of the PA, rather than acknowledging that thick complexity needs a different form of action. Co-production of knowledge is crucial for governance, but mainly not for the reasons for which it is promoted.

  15. [Local public health networks. Apropos of an experience].

    Science.gov (United States)

    Guix, Joan; Bocio, Ana; Ferràs, Joaquim; Margalef, Jordi; Osanz, Anna C; Serrano, Mónica; Sentenà, Anna

    2013-01-01

    Public health action on a territory is complex and requires the involvement of multiple actors, who do not always act coordinately. Networks of organizations structures including the whole of the local actors facilitate the generation of synergies and enable greater effectiveness and efficiency of the joint action from the different actors on a same landscape. We present 3 years experience of four Public Health Committees in a region of Catalonia (Spain), composed by the main actors in public health planning. Each of the committees is organized on a plenary and working groups on issues arising from the regional health diagnosis, and coincident with the Health Plan of the Region. Coordination in no case implies the loss or dilution of the firm of the actor generator of intervention initiative in public health, but their empowerment and collaboration by the other actors. In conclusion welcomes the creation of a culture of collaboration and synergies between the different organizations concerned. Lack of specificity is observed in establishing operational objectives, and the need for greater coordination and involvement of the components of the various working groups. Copyright © 2012 SESPAS. Published by Elsevier Espana. All rights reserved.

  16. Wireless Local Area Networks with Multiple-Packet Reception Capability

    CERN Document Server

    Zhang, Ying Jun; Liew, Soung Chang

    2007-01-01

    Thanks to its simplicity and cost efficiency, wireless local area network (WLAN) enjoys unique advantages in providing high-speed and low-cost wireless services in hot spots and indoor environments. Traditional WLAN medium-access-control (MAC) protocols assume that only one station can transmit at a time: simultaneous transmissions of more than one station causes the destruction of all packets involved. By exploiting recent advances in PHY-layer multiuser detection (MUD) techniques, it is possible for a receiver to receive multiple packets simultaneously. This paper argues that such multipacket reception (MPR) capability can greatly enhance the capacity of future WLANs. In addition, it provides the MAC-layer and PHY-layer designs needed to achieve the improved capacity. First, to demonstrate MUD/MPR as a powerful capacity-enhancement technique, we prove a "super-linearity" result, which states that the system throughput per unit cost increases as the MPR capability increases. Second, we show that the commonly...

  17. A Research Coordination Network for Ecological Applications of Terrestrial Laser Scanning

    Science.gov (United States)

    Condon, T. D.; Strahler, A. H.

    2016-12-01

    Enhancing the development of terrestrial laser scanning for ecological applications is the objective of a Research Coordination Network (RCN) now funded by the US National Science Foundation. The activity has two primary goals: (1) development of a low-cost lidar scanner that will provide accurate estimates of above-ground forest biomass for carbon modeling and monitoring procedures; and (2) development of a range of new ecological applications for TLS, based on rapid forest structure measurements and 3-D reconstructions of forest plots and stands. The network, first constituted in 2015, presently includes 69 participants, including researchers, professors, postdocs, and students at 32 institutions from Australia, Belgium, Canada, China, Finland, Netherlands, Switzerland, United Kingdom, and the United States. It is led by a Steering Committee of 15 researchers from 12 of these institutions. A primary activity of the TLSRCN is to facilitate communication of TLS developments and applications both within the group and to the broader scientific community at meetings and workshops. In 2015, RCN participants presented 27 papers and posters at international meetings and forums, including the Annual Conference of the Remote Sensing and Photogrammetry Society of the UK, SilviLaser 2015, and the Fall Meeting of the AGU. Within the group, bimonthly telecons allow the exchange of recent research developments and planning for group meetings and international conference presentations. Encouraging collaborative publications is also a focus of the RCN; 9 of 11 journal papers published in 2015 that reported TLS research by participants also combined authors from more than one research group participating in the network. The TLSRCN is supported by NSF Grant DBI-1455636 to Boston University, Alan Strahler Principal Investigator. Information for researchers interested in joining the network is available on the TLSRCN web site, tlsrcn.bu.edu. The image below shows a stand of Himalayan

  18. Application, validation and comparison in different geographical contexts of an integrated model for the design of ecological networks

    Directory of Open Access Journals (Sweden)

    Carmelo Riccardo Fichera

    2015-06-01

    Full Text Available The issue of the fragmentation of natural habitats is increasingly at the core of the scientific debate, but often not taken into due consideration in planning tools, with particular reference to the dynamism and complexity of landscapes. As it has been recognised at a European level, in order to allow different species to remain in good functional status, a network of green infrastructures should be implemented. The concept of ecological island is no longer sufficient to protect adequately the fauna and the ecosystem it lives in. Consequently, ecological islands must turn into ecological networks. The ecological connectivity refers to the way habitats are physically connected to each other and how easy it is for species to move in. Good ecological connectivity is fundamental to the effective conservation of biodiversity considering that most species and ecological functions provided by ecosystems (ecosystem services require a much wider space than that available within the boundaries of a single protected area. The main objective of this paper is to critically compare the application of a dedicated model for the design of ecological networks to two very different environmental contexts. This model was first tested in a Mediterranean area (the province of Reggio Calabria in 2008 and updated in 2010. The main goal was to integrate the traditional (physiographic and functional approaches into the design of ecological networks by taking into account biological and orographic elements as well as the anthropic structure of the territory. In 2011, within the ECONNECT European project, the same model was applied to the Pilot region of South- Western Alps (including the French region of Provence-Alpes-Côte d’Azur and the Italian regions Piedmont and Liguria, which is one of the richest transnational districts in Europe in terms of biodiversity. In such a region, the issue of multidisciplinary ecological connectivity was tackled in order to provide a

  19. A Study on Water Pollution Source Localization in Sensor Networks

    OpenAIRE

    Jun Yang; Xu Luo

    2016-01-01

    The water pollution source localization is of great significance to water environment protection. In this paper, a study on water pollution source localization is presented. Firstly, the source detection is discussed. Then, the coarse localization methods and the localization methods based on diffusion models are introduced and analyzed, respectively. In addition, the localization method based on the contour is proposed. The detection and localization methods are compared in experiments final...

  20. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation

    Directory of Open Access Journals (Sweden)

    Mehdi eBayati

    2015-06-01

    Full Text Available Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfirechains has been studied extensively in feed-forward networks ofspiking neurons. However, it remains unclear how such neural activity could emerge in recurrentneuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higherfrequency than the other, spontaneously active neurons in the network, can shapea network to allow for synchronous activity propagation. We use two-dimensional,locally connected and heterogeneous neuronal networks with spike-timingdependent plasticity (STDP. We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. Thisactivity originates from the site of the local excitation and propagates throughthe network.The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even inthe presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relativelysimple way in realistic neural networks by locally exciting the desired originof the neuronal sequence.

  1. Self-organization of synchronous activity propagation in neuronal networks driven by local excitation.

    Science.gov (United States)

    Bayati, Mehdi; Valizadeh, Alireza; Abbassian, Abdolhossein; Cheng, Sen

    2015-01-01

    Many experimental and theoretical studies have suggested that the reliable propagation of synchronous neural activity is crucial for neural information processing. The propagation of synchronous firing activity in so-called synfire chains has been studied extensively in feed-forward networks of spiking neurons. However, it remains unclear how such neural activity could emerge in recurrent neuronal networks through synaptic plasticity. In this study, we investigate whether local excitation, i.e., neurons that fire at a higher frequency than the other, spontaneously active neurons in the network, can shape a network to allow for synchronous activity propagation. We use two-dimensional, locally connected and heterogeneous neuronal networks with spike-timing dependent plasticity (STDP). We find that, in our model, local excitation drives profound network changes within seconds. In the emergent network, neural activity propagates synchronously through the network. This activity originates from the site of the local excitation and propagates through the network. The synchronous activity propagation persists, even when the local excitation is removed, since it derives from the synaptic weight matrix. Importantly, once this connectivity is established it remains stable even in the presence of spontaneous activity. Our results suggest that synfire-chain-like activity can emerge in a relatively simple way in realistic neural networks by locally exciting the desired origin of the neuronal sequence.

  2. QA/QC activities and ecological monitoring in the Acid Deposition Monitoring Network in East Asia (EANET

    Directory of Open Access Journals (Sweden)

    Ueda H

    2009-01-01

    Full Text Available An overview is presented of Quality assurance/Quality control QA/QC activities and current features of the ecological monitoring in the frame of the Acid Deposition Monitoring Network in East Asia EANET. It is stressed that standardization of the methodologies applicable for new topics, such as the catchment analysis and ozone impacts, should be investigated for future monitoring.

  3. Security Attacks in Optical Access Networks – Simultaneous Detection and Localization

    DEFF Research Database (Denmark)

    Saltykov, Anton; Glagolev, Sergey; Jensen, Jesper Bevensee

    2011-01-01

    Fiber macrobend tapping is a simple yet unsolved security breach in passive optical networks. We prove the possibility of such attacks, and propose a novel method for their detection and localization.......Fiber macrobend tapping is a simple yet unsolved security breach in passive optical networks. We prove the possibility of such attacks, and propose a novel method for their detection and localization....

  4. Local Short Period Seismic Network at Villarrica Volcano

    Science.gov (United States)

    Mora-Stock, Cindy; Thorwart, Martin; Dzieran, Laura; Rabbel, Wolfgang

    2014-05-01

    Since its last eruption in 1984-85, the Villarrica volcano has been presenting both seismic and fumarolic activity, accompanied by an open vent and a refulgent lava lake. To study its activity, a local seismic network of 75 DSS-Cubes short-period stations was deployed at and around the volcano. During the first two weeks of March, 2012, 30 3-Component and 45 1-Component stations were installed in a 63 km x 55 km area, with spacing between stations of 1.5 km for stations inside the perimeter of the volcanic edifice, and 5 km outside this perimeter. In total, approximately 94 volcano tectonic (VT) events with clear P- and S- wave arrivals were located to the SSW, SSE and North of the Crater at an average depth of 3 km below sea level. At least 73 events classified as "hybrids" (HB) were observed, predominantly about 2 km above sea level near or at the conduit. They present emergent higher frequencies at the beginning of the signal, and sharp S-wave at the crater stations, but a strong scattering, lower frequency content, and elongated coda on the stations along the volcanic edifice, probably due to ash layers and heterogeneities at the edifice. A few long period events (LP) with frequencies between 2-4 Hz were observed during the two weeks. Three set of groups can be distinguished for the regional tectonic events: aftershocks on the southern end of the rupture of the Maule 2010 event, with S-P wave travel time difference of ca. 30 s or more; a second group with S-P travel time difference between 10 s and 20s; and the much closer group with S-P wave difference of 10 s or less. To determine the average velocity structure of the volcano, a cross-correlation analysis of the waves from a M6.1 event in Argentina and other regional events was performed. The model used was a cylindric model of 6.5 km radius inside the volcanic edifice, which gave a P-wave velocity of 3.6 km/s, and a region outside this radius with a velocity of 4.1 km. The network was divided into five zones

  5. Research on the k-Coverage Local Wireless Network and Its Communication Coordination Mechanism Design

    OpenAIRE

    Yuan, Rongchang; Yuan, Haigan; Chen, Si; Sun, Longqing; Qin, Feng; Zhang,Han; Zhu, Yukun; Ma, Daokun

    2011-01-01

    Part 1: Decision Support Systems, Intelligent Systems and Artificial Intelligence Applications; International audience; Based on the analysis of the present situation and features of local wireless network, combined the networking technologies, we constructing the wireless network layout algorithm and sensor nodes model. Through delaminating iterative optimization algorithm, optimal layout of sensor data collection and satisfy recognition, quasi-geoids orientation, signal coverage optimizatio...

  6. Antibiotic treatment expands the resistance reservoir and ecological network of the phage metagenome.

    Science.gov (United States)

    Modi, Sheetal R; Lee, Henry H; Spina, Catherine S; Collins, James J

    2013-07-11

    The mammalian gut ecosystem has considerable influence on host physiology, but the mechanisms that sustain this complex environment in the face of different stresses remain obscure. Perturbations to the gut ecosystem, such as through antibiotic treatment or diet, are at present interpreted at the level of bacterial phylogeny. Less is known about the contributions of the abundant population of phages to this ecological network. Here we explore the phageome as a potential genetic reservoir for bacterial adaptation by sequencing murine faecal phage populations following antibiotic perturbation. We show that antibiotic treatment leads to the enrichment of phage-encoded genes that confer resistance via disparate mechanisms to the administered drug, as well as genes that confer resistance to antibiotics unrelated to the administered drug, and we demonstrate experimentally that phages from treated mice provide aerobically cultured naive microbiota with increased resistance. Systems-wide analyses uncovered post-treatment phage-encoded processes related to host colonization and growth adaptation, indicating that the phageome becomes broadly enriched for functionally beneficial genes under stress-related conditions. We also show that antibiotic treatment expands the interactions between phage and bacterial species, leading to a more highly connected phage-bacterial network for gene exchange. Our work implicates the phageome in the emergence of multidrug resistance, and indicates that the adaptive capacity of the phageome may represent a community-based mechanism for protecting the gut microflora, preserving its functional robustness during antibiotic stress.

  7. Rooted-tree network for optimal non-local gate implementation

    Science.gov (United States)

    Vyas, Nilesh; Saha, Debashis; Panigrahi, Prasanta K.

    2016-09-01

    A general quantum network for implementing non-local control-unitary gates, between remote parties at minimal entanglement cost, is shown to be a rooted-tree structure. Starting from a five-party scenario, we demonstrate the local implementation of simultaneous class of control-unitary(Hermitian) and multiparty control-unitary gates in an arbitrary n-party network. Previously, established networks are turned out to be special cases of this general construct.

  8. ENHANCED COMPOSITE APPROACH WITH MOBILE BEACON SHORTEST PATH TO SOLVE LOCALIZATION PROBLEM IN WIRELESS SENSOR NETWORK

    Directory of Open Access Journals (Sweden)

    Sunil Kumar,

    2010-12-01

    Full Text Available Wireless sensor network is tremendously being used in different environments to perform various monitoring task such as search, rescue, disaster relief, target tracking and a number of tasks in smart environment. In this paper a unique localization algorithm is proposed that gives the high accuracy in wireless sensor network. We propose amobile beacon algorithm and then merge it with DV- hop algorithm to introduce a unique approach which solves the localization problem in wireless sensor network.

  9. Wireless Local Area Network Performance Inside Aircraft Passenger Cabins

    Science.gov (United States)

    Whetten, Frank L.; Soroker, Andrew; Whetten, Dennis A.; Whetten, Frank L.; Beggs, John H.

    2005-01-01

    An examination of IEEE 802.11 wireless network performance within an aircraft fuselage is performed. This examination measured the propagated RF power along the length of the fuselage, and the associated network performance: the link speed, total throughput, and packet losses and errors. A total of four airplanes: one single-aisle and three twin-aisle airplanes were tested with 802.11a, 802.11b, and 802.11g networks.

  10. Convolutional LSTM Networks for Subcellular Localization of Proteins

    OpenAIRE

    Sønderby, Søren Kaae; Sønderby, Casper Kaae; Nielsen, Henrik; Winther, Ole

    2015-01-01

    Machine learning is widely used to analyze biological sequence data. Non-sequential models such as SVMs or feed-forward neural networks are often used although they have no natural way of handling sequences of varying length. Recurrent neural networks such as the long short term memory (LSTM) model on the other hand are designed to handle sequences. In this study we demonstrate that LSTM networks predict the subcellular location of proteins given only the protein sequence with high accuracy (...

  11. Convolutional LSTM Networks for Subcellular Localization of Proteins

    DEFF Research Database (Denmark)

    Nielsen, Henrik; Sønderby, Søren Kaae; Sønderby, Casper Kaae

    Machine learning is widely used to analyze biological sequence data. Non-sequential models such as SVMs or feed-forward neural networks are often used although they have no natural way of handling sequences of varying length. Recurrent neural networks such as the long short term memory (LSTM) model...... on the other hand are designed to handle sequences. In this study we demonstrate that LSTM networks predict the subcellular location of proteins given only the protein sequence with high accuracy (0.902) outperforming current state of the art algorithms. We further improve the performance by introducing...... the LSTM networks....

  12. The Changing Cold Regions Network: Atmospheric, Cryospheric, Ecological and Hydrological Change in the Saskatchewan and Mackenzie River Basins, Canada (Invited)

    Science.gov (United States)

    Wheater, H. S.; DeBeer, C.

    2013-12-01

    The cold interior of Northwestern Canada has one of the world's most extreme and varied climates and, as with other regions across the Arctic, is experiencing rapid environmental change. The Changing Cold Regions Network (CCRN) is a new Canadian research network devoted to addressing key challenges and globally-important issues facing the Arctic by improving the understanding of past and ongoing changes in climate, land, vegetation, and water, and predicting their future integrated responses, with a geographic focus on the Saskatchewan and Mackenzie River Basins. The network is funded for 5 years (2013-18) by the Natural Sciences and Engineering Research Council of Canada, and combines the unique expertise of 36 Canadian scientists representing 8 universities and 4 Federal government agencies, as well as 15 international researchers from the United States, China, Australia, the UK, France, and Germany. The network will also involve the World Climate Research Programme, NASA, the Canadian Space Agency, and the National Center for Atmospheric Research. CCRN will integrate existing and new experimental data with modelling and remote sensing products to understand, diagnose and predict changing land, water and climate, and their interactions and feedbacks, for Northwestern Canada's cold interior. It will use a network of world class observatories to study the detailed connections among changing climate, ecosystems and water in the permafrost regions of the Sub-arctic, the Boreal Forest, the Western Cordillera, and the Prairies. Specifically, the network will: 1. Document and evaluate observed Earth system change, including hydrological, ecological, cryospheric and atmospheric components over a range of scales from local observatories to biome and regional scales; 2. Improve understanding and diagnosis of local-scale change by developing new and integrative knowledge of Earth system processes, incorporating these processes into a suite of process-based integrative

  13. Ecological Values amid Local Interests: Natural Resource Conservation, Social Differentiation, and Human Survival in Honduras

    Science.gov (United States)

    Gareau, Brian J.

    2007-01-01

    Local peoples living in protected areas often have a different understanding about their natural space than do non-local groups that promote and declare such areas "protected." By designing protected areas without local involvement, or understandings of local social differentiation and power, natural resources management schemes will likely be…

  14. Convolutional LSTM Networks for Subcellular Localization of Proteins

    DEFF Research Database (Denmark)

    Sønderby, Søren Kaae; Sønderby, Casper Kaae; Nielsen, Henrik;

    2015-01-01

    Machine learning is widely used to analyze biological sequence data. Non-sequential models such as SVMs or feed-forward neural networks are often used although they have no natural way of handling sequences of varying length. Recurrent neural networks such as the long short term memory (LSTM) mod...

  15. Power-law weighted networks from local attachments

    CERN Document Server

    Moriano, P

    2011-01-01

    Large networks arise by the gradual addition of nodes attaching to an existing and evolving network component. There are a wide class of attachment strategies which lead to distinct structural features in growing networks. This paper introduces a mechanism for constructing, through a process of distributed decision-making, substrates for the study of collective dynamics on power-law weighted networks with both a desired scaling exponent and a fixed clustering coefficient. The analytical results show that the connectivity distribution converges to the scaling behavior often found in social and engineering systems. To illustrate the approach of the proposed framework we generate network substrates that resemble the empirical citation distributions of (i) publications indexed by the Institute for Scientific Information from 1981 to 1997; (ii) patents granted by the U.S. Patent and Trademark Office from 1975 to 1999; and (iii) opinions written by the Supreme Court and the cases they cite from 1754 to 2002.

  16. On Distributed Localization for Road Sensor Networks: A Game Theoretic Approach

    Directory of Open Access Journals (Sweden)

    Jie Jia

    2013-01-01

    Full Text Available Road sensor network is an important part of vehicle networks system and is critical for many intelligent automobile scenarios, such as vehicle safety monitoring and transportation efficiency supporting. Localization of sensors is an active and crucial issue to most applications of road sensor network. Generally, given some anchor nodes’ positions and certain pairwise distance measurements, estimating the positions of all nonanchor nodes embodies a nonconvex optimization problem. However, due to the small number of anchor nodes and low sensor node connectivity degree in road sensor networks, the existing localization solutions are ineffective. In order to tackle this problem, a novel distributed localization method based on game theory for road sensor networks is proposed in this paper. Formally, we demonstrate that our proposed localization game is a potential game. Furthermore, we present several techniques to accelerate the convergence to the optimal solution. Simulation results demonstrate the effectiveness of our proposed algorithm.

  17. CluLoR: Clustered Localized Routing for FiWi Networks

    Directory of Open Access Journals (Sweden)

    Yousef Dashti

    2014-04-01

    Full Text Available The integration of passive optical networks (PONs and wireless mesh networks (WMNs into Fiber- Wireless (FiWi networks can lead to effective access networks. Existing routing schemes for FiWi networks consider mainly hop-count and delay metrics over a flat WMN node topology and do not specifically prioritize the local network structure, i.e., the local wireless-optical network gateway. In this study, we explore a simple, yet effective routing algorithm for FiWi networks with a WMN organized into zones operating on different radio channels. We examine the effects of routing the traffic into and out of a zone through one or more cluster heads. We investigate the effectiveness of localized routing that prioritizes transmissions over the local gateway to the optical network and avoids wireless packet transmissions in zones that do not contain the packet source or destination. We find that this combination of clustered and localized routing (CluLoR gives good throughput-delay performance compared to routing schemes that transmit packets wirelessly through “transit zones” (that do not contain the packet source or destination following minimum hop-count routing.

  18. Interconnection between packet switching national networks and local packet radio communication networks

    Science.gov (United States)

    Talone, P.; Trigila, S.

    1985-07-01

    Multipoint topology networks based on a single statistically distributed radiocommunication channel are considered, referring only to restricted area networks with line of sight type links. The architecture and protocols of such networks are reviewed. The problems related to the interconnection of such networks with large public packet switching communication networks are examined. Several hypothesis are studied concluding that mainly in the case of emergencies or catastrophic events these networks are an extremely useful resource.

  19. Local development and Local Partnerships: Universities applying pro-active PR in a local systems network logics

    OpenAIRE

    Arta Musaraj

    2010-01-01

    Facing turmoil and continuous stunning, local governing bodies, decision makers and local actors, in most of cases found the most stable solution has been the regional cooperation and particularly that of increasing and strengthening local human resources capacities at a regional level. Trying to increase competiveness, local systems understand more and more the importance of being flexible, on the frame of a sustainable strategic planning. Local infrastructure and interaction of all local fa...

  20. Exploring Interconnections between Local Ecological Knowledge, Professional Identity and Sense of Place among Swedish Fishers

    Science.gov (United States)

    Garavito-Bermúdez, Diana; Lundholm, Cecilia

    2017-01-01

    The ecological knowledge of those who interact with ecosystems in everyday-life is situated in social and cultural contexts, as well as accumulated, transferred and adjusted through work practices. For them, ecosystems represent not only places for living but also places for working and defining themselves. This paper explores psychological…

  1. Target Localization Based on Improved DV-Hop Algorithm in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Xiaolong Huang

    2014-01-01

    Full Text Available The node localization technology of wireless sensor networks is essential and prerequisite to many applications, which it is one of the important support technologies for wireless sensor networks. The node localization is to get the position information of blind node by using location information of few known nodes and some special mechanisms. This paper primarily investigates a kind of target localization technology based on the improved DV-Hop algorithm in wireless sensor networks. We firstly compute the distances measured by RSSI and the mean value of one-hop distance. Then we can use the differences between the mean and the actual distance to get the error correction between the total distance and average one-hop distance. Replace trilateration with hybrid localization of MIN-MAX and weighted least square method. Finally, simulation experiment results show the improved algorithm can effectively carry out the network localization, thus has a certain of practical value

  2. Improved Local Weather Forecasts Using Artificial Neural Networks

    DEFF Research Database (Denmark)

    Wollsen, Morten Gill; Jørgensen, Bo Nørregaard

    2015-01-01

    Solar irradiance and temperature forecasts are used in many different control systems. Such as intelligent climate control systems in commercial greenhouses, where the solar irradiance affects the use of supplemental lighting. This paper proposes a novel method to predict the forthcoming weather...... using an artificial neural network. The neural network used is a NARX network, which is known to model non-linear systems well. The predictions are compared to both a design reference year as well as commercial weather forecasts based upon numerical modelling. The results presented in this paper show...

  3. AC Power Local Network with Multiple Power Routers

    Directory of Open Access Journals (Sweden)

    Ryo Takahashi

    2013-12-01

    Full Text Available Controlling power flow and achieving appropriate matching between power sources and loads according to the quality of energy is expected to be one of the approaches to reduce wasted energy consumption. A power router, proposed recently, has the capability of realizing circuit switching in a power distribution network. This study focuses on the feasibility of an AC power routing network system composed of multiple power routers. To evaluate the feasibility, we experimentally confirm the circuit switching operation of the parallel and series configurations of the power routers, so that the network system can be designed by the combination of parallel and series configurations.

  4. Convolutional LSTM Networks for Subcellular Localization of Proteins

    DEFF Research Database (Denmark)

    Sønderby, Søren Kaae; Sønderby, Casper Kaae; Nielsen, Henrik

    2015-01-01

    Machine learning is widely used to analyze biological sequence data. Non-sequential models such as SVMs or feed-forward neural networks are often used although they have no natural way of handling sequences of varying length. Recurrent neural networks such as the long short term memory (LSTM) model...... on the other hand are designed to handle sequences. In this study we demonstrate that LSTM networks predict the subcellular location of proteins given only the protein sequence with high accuracy (0.902) outperforming current state of the art algorithms. We further improve the performance by introducing...

  5. Detectability and reliability analysis of the local seismic network in Pakistan

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The detectability and reliability analysis for the local seismic network is performed employing by Bungum and Husebye technique. The events were relocated using standard computer codes for hypocentral locations. The detectability levels are estimated from the twenty-five years of recorded data in terms of 50(, 90( and 100( cumulative detectability thresholds, which were derived from frequency-magnitude distribution. From this analysis the 100( level of detectability of the network is ML=1.7 for events which occur within the network. The accuracy in hypocentral solutions of the network is investigated by considering the fixed real hypocenter within the network. The epicentral errors are found to be less than 4 km when the events occur within the network. Finally, the problems faced during continuous operation of the local network, which effects its detectability, are discussed.

  6. Adaptability and resilience predict with „youth homeless” group in local system on prevention in context of Urie Bronfenbrenner developmental ecological model

    OpenAIRE

    Małgorzata Michel

    2013-01-01

    This article includes the analysis of possibility specific adaptability and resilience predict with „youth homeless” group in Local System of Prevention in context of Urie Bronfenbrenner developmental ecological model.

  7. Adaptability and resilience predict with „youth homeless” group in local system on prevention in context of Urie Bronfenbrenner developmental ecological model

    Directory of Open Access Journals (Sweden)

    Małgorzata Michel

    2013-06-01

    Full Text Available This article includes the analysis of possibility specific adaptability and resilience predict with „youth homeless” group in Local System of Prevention in context of Urie Bronfenbrenner developmental ecological model.

  8. EDENetworks: a user-friendly software to build and analyse networks in biogeography, ecology and population genetics.

    Science.gov (United States)

    Kivelä, Mikko; Arnaud-Haond, Sophie; Saramäki, Jari

    2015-01-01

    The recent application of graph-based network theory analysis to biogeography, community ecology and population genetics has created a need for user-friendly software, which would allow a wider accessibility to and adaptation of these methods. EDENetworks aims to fill this void by providing an easy-to-use interface for the whole analysis pipeline of ecological and evolutionary networks starting from matrices of species distributions, genotypes, bacterial OTUs or populations characterized genetically. The user can choose between several different ecological distance metrics, such as Bray-Curtis or Sorensen distance, or population genetic metrics such as FST or Goldstein distances, to turn the raw data into a distance/dissimilarity matrix. This matrix is then transformed into a network by manual or automatic thresholding based on percolation theory or by building the minimum spanning tree. The networks can be visualized along with auxiliary data and analysed with various metrics such as degree, clustering coefficient, assortativity and betweenness centrality. The statistical significance of the results can be estimated either by resampling the original biological data or by null models based on permutations of the data. © 2014 John Wiley & Sons Ltd.

  9. Implementation of SNS Model for Intrusion Prevention in Wireless Local Area Network

    DEFF Research Database (Denmark)

    Isah, Abdullahi

    The thesis has proposed and implemented a so-called SNS (Social network security) model for intrusion prevention in the Wireless Local Area Network of an organization. An experimental design was used to implement and test the model at a university in Nigeria.......The thesis has proposed and implemented a so-called SNS (Social network security) model for intrusion prevention in the Wireless Local Area Network of an organization. An experimental design was used to implement and test the model at a university in Nigeria....

  10. Local identification of piecewise deterministic models of genetic networks

    NARCIS (Netherlands)

    Cinquemani, Eugenio; Milias-Argeitis, Andreas; Summers, Sean; Lygeros, John

    2009-01-01

    We address the identification of genetic networks under stationary conditions. A stochastic hybrid description of the genetic interactions is considered and an approximation of it in stationary conditions is derived. Contrary to traditional structure identification methods based on fitting determini

  11. The Tropical Ecology, Assessment and Monitoring (TEAM) Network: An early warning system for tropical rain forests.

    Science.gov (United States)

    Rovero, Francesco; Ahumada, Jorge

    2017-01-01

    While there are well established early warning systems for a number of natural phenomena (e.g. earthquakes, catastrophic fires, tsunamis), we do not have an early warning system for biodiversity. Yet, we are losing species at an unprecedented rate, and this especially occurs in tropical rainforests, the biologically richest but most eroded biome on earth. Unfortunately, there is a chronic gap in standardized and pan-tropical data in tropical forests, affecting our capacity to monitor changes and anticipate future scenarios. The Tropical Ecology, Assessment and Monitoring (TEAM) Network was established to contribute addressing this issue, as it generates real time data to monitor long-term trends in tropical biodiversity and guide conservation practice. We present the Network and focus primarily on the Terrestrial Vertebrates protocol, that uses systematic camera trapping to detect forest mammals and birds, and secondarily on the Zone of Interaction protocol, that measures changes in the anthroposphere around the core monitoring area. With over 3 million images so far recorded, and managed using advanced information technology, TEAM has created the most important data set on tropical forest mammals globally. We provide examples of site-specific and global analyses that, combined with data on anthropogenic disturbance collected in the larger ecosystem where monitoring sites are, allowed us to understand the drivers of changes of target species and communities in space and time. We discuss the potential of this system as a candidate model towards setting up an early warning system that can effectively anticipate changes in coupled human-natural system, trigger management actions, and hence decrease the gap between research and management responses. In turn, TEAM produces robust biodiversity indicators that meet the requirements set by global policies such as the Aichi Biodiversity Targets. Standardization in data collection and public sharing of data in near real time

  12. Considerations for a Shipboard Multilevel Secure Local Area Network

    Science.gov (United States)

    1992-03-01

    fulfillment of the requirements for the degree of MASTER OF SCIENCE IN TELECOMMUNICATIONS SYSTEMS MANAGEMENT from the NAVAL POSTGRADUATE SCHOOL March 1992...Intentions arc to merge the three separate networks into one network, the DISNET. Physicall % unprotected trunks and host access lines on the MILNET are being...Computer Security Press. April 19S2. 13. Computers at Risk: Safe Computing in the Information Ave. System Security Stud% Committee, Computer Science and

  13. From local to global dilemmas in social networks.

    Directory of Open Access Journals (Sweden)

    Flávio L Pinheiro

    Full Text Available Social networks affect in such a fundamental way the dynamics of the population they support that the global, population-wide behavior that one observes often bears no relation to the individual processes it stems from. Up to now, linking the global networked dynamics to such individual mechanisms has remained elusive. Here we study the evolution of cooperation in networked populations and let individuals interact via a 2-person Prisoner's Dilemma--a characteristic defection dominant social dilemma of cooperation. We show how homogeneous networks transform a Prisoner's Dilemma into a population-wide evolutionary dynamics that promotes the coexistence between cooperators and defectors, while heterogeneous networks promote their coordination. To this end, we define a dynamic variable that allows us to track the self-organization of cooperators when co-evolving with defectors in networked populations. Using the same variable, we show how the global dynamics--and effective dilemma--co-evolves with the motifs of cooperators in the population, the overall emergence of cooperation depending sensitively on this co-evolution.

  14. Suburban waterfront with ecological and recreational function: planning based on network analysis

    Directory of Open Access Journals (Sweden)

    Natalia Fumagalli

    2014-02-01

    Full Text Available Urban fringe areas have multiple land uses and are places where sections of waterway, together with fragmented areas of natural vegetation, are often found passing through urban areas, transportation routes and gradually expanding rural areas. These overlapping functions are often the cause of an extremely disorderly landscape devoid of guiding connotative elements. In this context, the waterfront can be a guiding element for the redevelopment of the fringe areas between cities and the countryside. The purpose of this paper is the definition of a methodology for planning a suburban waterfront with an ecological function and bicycle paths for recreational use. The evaluation phases for resources and planning, conducted with tools for network analysis, have identified potential corridors based on current land uses and have addressed the issue of bicycle paths on an inter-municipal scale. The methodology is proposed for regional level planning and the validation of the method was achieved through its application to the stretch of the Lambro River between Monza Park and the city of Milan in the North of Italy.

  15. Intrinsic excitability state of local neuronal population modulates signal propagation in feed-forward neural networks.

    Science.gov (United States)

    Han, Ruixue; Wang, Jiang; Yu, Haitao; Deng, Bin; Wei, Xilei; Qin, Yingmei; Wang, Haixu

    2015-04-01

    Reliable signal propagation across distributed brain areas is an essential requirement for cognitive function, and it has been investigated extensively in computational studies where feed-forward network (FFN) is taken as a generic model. But it is still unclear how distinct local network states, which are intrinsically generated by synaptic interactions within each layer, would affect the ability of FFN to transmit information. Here we investigate the impact of such network states on propagating transient synchrony (synfire) and firing rate by a combination of numerical simulations and analytical approach. Specifically, local network dynamics is attributed to the competition between excitatory and inhibitory neurons within each layer. Our results show that concomitant with different local network states, the performance of signal propagation differs dramatically. For both synfire propagation and firing rate propagation, there exists an optimal local excitability state, respectively, that optimizes the performance of signal propagation. Furthermore, we find that long-range connections strongly change the dependence of spiking activity propagation on local network state and propose that these two factors work jointly to determine information transmission across distributed networks. Finally, a simple mean field approach that bridges response properties of long-range connectivity and local subnetworks is utilized to reveal the underlying mechanism.

  16. Defining ecologically relevant scales for spatial protection with long-term data on an endangered seabird and local prey availability.

    Science.gov (United States)

    Sherley, Richard B; Botha, Philna; Underhill, Les G; Ryan, Peter G; van Zyl, Danie; Cockcroft, Andrew C; Crawford, Robert J M; Dyer, Bruce M; Cook, Timothée R

    2017-03-01

    Human activities are important drivers of marine ecosystem functioning. However, separating the synergistic effects of fishing and environmental variability on the prey base of non-target predators is difficult, often because prey availability estimates on appropriate scales are lacking. Understanding how prey abundance at different spatial scales links to population change can help integrate the needs of non-target predators into fisheries management by defining ecologically-relevant areas for spatial protection. We investigated the local population response (number of breeders) of the bank cormorant Phalacrocorax neglectus, a range-restricted endangered seabird, to the availability of its prey, the heavily-fished west coast rock lobster Jasus lalandii. Using Bayesian state-space modeled cormorant counts at three colonies, 22 years of fisheries-independent data on local lobster abundance and generalized additive modeling, we determined the spatial-scale pertinent to these relationships in areas of differing lobster availability. Cormorant numbers responded positively to lobster availability in the intermediate and high abundance regions, but not where regime shifts and fishing pressure have depleted lobster stocks. The relationships were strongest at 20-30 km, greater than the cormorants' foraging range when breeding, and may have been influence by prey availability for non-breeding birds, prey switching or prey ecology. Our results highlight the importance of considering the scale of ecological relationships in marine spatial planning and suggest that designing spatial protection around focal species can benefit marine predators across their full life cycle. We propose the precautionary implementation of small-scale marine protected areas, followed by robust assessment and adaptive-management, to confirm population-level benefits for the cormorants, their prey and the wider ecosystem, without negative impacts on local fisheries. This article is protected by

  17. Sustainability Evaluation of the Grain for Green Project: From Local People's Responses to Ecological Effectiveness in Wolong Nature Reserve

    Science.gov (United States)

    Xu, Jian-Ying; Chen, Li-Ding; Lu, Yi-He; Fu, Bo-Jie

    2007-07-01

    This article examines the sustainability of the Grain for Green Project in the Wolong Nature Reserve. Pertinent data were collected through a questionnaire survey and a spatial analysis of reforested lands. The study results identified four critical issues that may influence the sustainability of the project in the study area. The first issue is concerned with the project’s impacts on local sustenance. Because local grain consumption depends greatly on compensation awarded by the project, the potential for sustainability of the project is compromised. The second issue is that the project causes negative effects on local incomes in the Wolong Nature Reserve, which may undermine local economic prospects. The third issue is that the project failed to deliver suitable habitat for the giant panda, although two of the suitability requirements that deal with landform features were met. Lastly, the project neglects great differences among geographical areas in the country, providing the same compensation and length of compensation period to all participants. Appropriate compensation mechanisms should be established and adapted to local economic, environmental, and social conditions. In managing nature reserves and moving toward sustainability, ensuring all aspects of local socioeconomic and ecological/environmental issues are properly addressed is a real challenge. Based on our study, some recommendations for improving sustainability of the project are given.

  18. Delivery of video-on-demand services using local storages within passive optical networks.

    Science.gov (United States)

    Abeywickrama, Sandu; Wong, Elaine

    2013-01-28

    At present, distributed storage systems have been widely studied to alleviate Internet traffic build-up caused by high-bandwidth, on-demand applications. Distributed storage arrays located locally within the passive optical network were previously proposed to deliver Video-on-Demand services. As an added feature, a popularity-aware caching algorithm was also proposed to dynamically maintain the most popular videos in the storage arrays of such local storages. In this paper, we present a new dynamic bandwidth allocation algorithm to improve Video-on-Demand services over passive optical networks using local storages. The algorithm exploits the use of standard control packets to reduce the time taken for the initial request communication between the customer and the central office, and to maintain the set of popular movies in the local storage. We conduct packet level simulations to perform a comparative analysis of the Quality-of-Service attributes between two passive optical networks, namely the conventional passive optical network and one that is equipped with a local storage. Results from our analysis highlight that strategic placement of a local storage inside the network enables the services to be delivered with improved Quality-of-Service to the customer. We further formulate power consumption models of both architectures to examine the trade-off between enhanced Quality-of-Service performance versus the increased power requirement from implementing a local storage within the network.

  19. DIAGNOSTICS OF READINESS OF TEACHERS TO THE EXTRACURRICULAR ACTIVITIES OF ELEMENTARY SCHOOL STUDENTS IN ECOLOGICAL AND LOCAL HISTORY

    Directory of Open Access Journals (Sweden)

    Maria Viktorovna Sineva

    2015-05-01

    Full Text Available This paper considers the problem of preparation of the future teacher to the organization of extracurricular activities in environmental (ecological and local history for younger students and dedicated to this aspect in the implementation of the Federal state educational standard of the new generation. It describes the components of professional readiness of the future teacher for this type of activity; analyzes the results of the evaluation of the readiness of the future teachers carried out by the author developed criteria, indicators and diagnostic tools. Materials can be used by teachers of pedagogical universities and teacher training institutes.

  20. Global Brand Identity as a Network of Localized Meanings

    NARCIS (Netherlands)

    Gunawan, Elizabeth; van den Hoven, P.J.|info:eu-repo/dai/nl/070378096

    2017-01-01

    In this article, we develop a semiotic model to analyze advertisement localization. This model focuses on the mental representations that local audiences build of a “global” brand identity. We demonstrate how this model fills up gaps left by a popular marketing model for global advertising. We argue

  1. $k$-core percolation on complex networks: Comparing random, localized and targeted attacks

    CERN Document Server

    Yuan, Xin; Stanley, H Eugene; Havlin, Shlomo

    2016-01-01

    The type of malicious attack inflicting on networks greatly influences their stability under ordinary percolation in which a node fails when it becomes disconnected from the giant component. Here we study its generalization, $k$-core percolation, in which a node fails when it loses connection to a threshold $k$ number of neighbors. We study and compare analytically and by numerical simulations of $k$-core percolation the stability of networks under random attacks (RA), localized attacks (LA) and targeted attacks (TA), respectively. By mapping a network under LA or TA into an equivalent network under RA, we find that in both single and interdependent networks, TA exerts the greatest damage to the core structure of a network. We also find that for Erd\\H{o}s-R\\'{e}nyi (ER) networks, LA and RA exert equal damage to the core structure whereas for scale-free (SF) networks, LA exerts much more damage than RA does to the core structure.

  2. Global optimization, local adaptation and the role of growth in distribution networks

    CERN Document Server

    Ronellenfitsch, Henrik

    2016-01-01

    Highly-optimized complex transport networks serve crucial functions in many man-made and natural systems such as power grids and plant or animal vasculature. Often, the relevant optimization functional is non-convex and characterized by many local extrema. In general, finding the global, or nearly global optimum is difficult. In biological systems, it is believed that natural selection slowly guides the network towards an optimized state. However, general coarse grained models for flow networks with local positive feedback rules for the vessel conductivity typically get trapped in low efficiency, local minima. In this work we show how the growth of the underlying tissue, coupled to the dynamical equations for network development, can drive the system to a dramatically improved optimal state. This general model provides a surprisingly simple explanation for the appearance of highly optimized transport networks in biology such as leaf and animal vasculature.

  3. Scalable and Fully Distributed Localization in Large-Scale Sensor Networks

    Directory of Open Access Journals (Sweden)

    Miao Jin

    2017-06-01

    Full Text Available This work proposes a novel connectivity-based localization algorithm, well suitable for large-scale sensor networks with complex shapes and a non-uniform nodal distribution. In contrast to current state-of-the-art connectivity-based localization methods, the proposed algorithm is highly scalable with linear computation and communication costs with respect to the size of the network; and fully distributed where each node only needs the information of its neighbors without cumbersome partitioning and merging process. The algorithm is theoretically guaranteed and numerically stable. Moreover, the algorithm can be readily extended to the localization of networks with a one-hop transmission range distance measurement, and the propagation of the measurement error at one sensor node is limited within a small area of the network around the node. Extensive simulations and comparison with other methods under various representative network settings are carried out, showing the superior performance of the proposed algorithm.

  4. An Effective Local Routing Strategy on the Communication Network

    Science.gov (United States)

    Li, Yu-Jian; Wang, Bing-Hong; Xi, Zheng-Dong; Yin, Chuan-Yang; Yang, Han-Xin; Sun, Duo

    In this paper, we propose an effective routing strategy on the basis of the so-called nearest neighbor search strategy by introducing a preferential cut-off exponent K. We assume that the handling capacity of one vertex is proportional to its degree when the degree is smaller than K, and is a constantC 0 otherwise. It is found that by tuning the parameter α, the scale-free network capacity measured by the order parameter is considerably enhanced compared to the normal nearest-neighbor strategy. Traffic dynamics both near and far away from the critical generating rate R c are discussed. Simulation results demonstrate that the optimal performance of the system corresponds to α= - 0.5. Due to the low cost of acquiring nearest-neighbor information and the strongly improved network capacity, our strategy may be useful and reasonable for the protocol designing of modern communication networks.

  5. Frequency Transmission Control of Local Networked Control Systems Approach

    Directory of Open Access Journals (Sweden)

    O. Esquivel-Flores

    2012-08-01

    Full Text Available The use of Network Control Systems has been successful in the industry and therefore has opened several lines ofresearch. Control systems over a communication network include two important considerations, control andscheduling. Co-design strategies are focused on maintaining adequate control performance and maximize the level ofservice. Network scheduling is the main objective to resolve because through a balanced data load is possible tomaintain control performance in a desired level. This article reviews a scheduling strategy based on frequencytransition modeled as a linear subsystem, this control reconfigure on line the sensors’ periods. The case of study isthe control of a prototype helicopter and by numerical simulations it shows the effect of changing the transmissionfrequency.

  6. Expert and Generalist Local Knowledge about Land-cover Change on South Africa's Wild Coast: Can Local Ecological Knowledge Add Value to Science?

    Directory of Open Access Journals (Sweden)

    Nigel Chalmers

    2007-06-01

    Full Text Available Local ecological knowledge (LEK can shed light on ecosystem change, especially in under-researched areas such as South Africa's Wild Coast. However, for ecosystem planning purposes, it is necessary to assess the accuracy and validity of LEK, and determine where such knowledge is situated in a community, and how evenly it is spread. Furthermore, it is relevant to ask: does LEK add value to science, and how do science and local knowledge complement one another? We assessed change in woodland and forest cover in the Nqabara Administrative Area on South Africa's Wild Coast between 1974 and 2001. The inhabitants of Nqabara are "traditional" Xhosa-speaking people who are highly dependent on natural resources for their livelihoods. More recently, however, infrastructural development has influenced traditional lifestyles at Nqabara, although poverty remains high and formal education levels low. We assessed LEK about changes in woodland and forest cover over the past 30 years by interviewing 11 local "experts," who were recognized as such by the Nqabara community, and 40 senior members of randomly selected households in each village. We also analyzed land-cover change, using orthorectified aerial photos taken in 1974 and 2001. Forest and woodland cover had increased by 49% between 1974 and 2001. The 11 "experts" had a nuanced understanding of these changes and their causes. Their understanding was not only remarkably consistent with that of scientists, but it added considerable value to scientific understanding of the ultimate causes of land-cover change in the area. The experts listed combinations of several causal factors, operating at different spatial and temporal scales. The 40 randomly selected respondents also knew that forest and woodland cover had increased, but their understanding of the causes, and the role of fire in particular, was somewhat simplistic. They could identify only three causal factors and generally listed single factors rather

  7. Local post-harvest practices associated with aflatoxin and fumonisin contamination of maize in three agro ecological zones of Tanzania.

    Science.gov (United States)

    Kamala, Analice; Kimanya, Martin; Haesaert, Geert; Tiisekwa, Bendantuguka; Madege, Richard; Degraeve, Szanne; Cyprian, Cypriana; De Meulenaer, Bruno

    2016-01-01

    A survey was undertaken of a total of 120 farmers, 40 from each of the three studied agro-ecological zones of Tanzania, to determine local post-harvest management practices associated with aflatoxin (AF) and fumonisin (FB) contamination of maize. Data on practices (collected using a structured questionnaire) and maize samples were obtained from each of the 120 farmers. FB and AF contamination in the samples were analysed by HPLC. A total of 45% and 85% of maize samples were positive for AF and FB respectively, with levels ranging from 0.1 to 269 μg kg(-1) for AF and from 49 to 18 273 μg kg(-1) for FBs. Significant differences in contamination level were observed among the three agro-ecological zones. Farmers in the three agro-ecological zones practised similar practices in varying degrees. Drying, sorting and protecting maize against insect infestation are practices that showed significant association with AF or FB contamination of maize. Drying maize on mat/raised platform, sorting (damaged, discoloured and moulded grains) and application of synthetic insecticides during storage are practices that were associated with less contamination of maize with AF and FB. The results can be used to advise on effective post-harvest strategies for prevention of AF and FB contamination of maize in rural Tanzania.

  8. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru Miyauchi; Yanjun Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirmlow optical loss and environmental stabilities.

  9. High-Speed Optical Local Access Network System Using Bi-Directional Polarization Multiplexing

    Institute of Scientific and Technical Information of China (English)

    Mitsuru; Miyauchi; Yanjun; Sun

    2003-01-01

    A high-speed and economical optical local access network system is proposed where bi-directional polarization multiplexing is applied to a bi-directional transmission. Experimental results using a prototype system confirm low optical loss and environmental stabilities.

  10. An improved localization algorithm based on genetic algorithm in wireless sensor networks.

    Science.gov (United States)

    Peng, Bo; Li, Lei

    2015-04-01

    Wireless sensor network (WSN) are widely used in many applications. A WSN is a wireless decentralized structure network comprised of nodes, which autonomously set up a network. The node localization that is to be aware of position of the node in the network is an essential part of many sensor network operations and applications. The existing localization algorithms can be classified into two categories: range-based and range-free. The range-based localization algorithm has requirements on hardware, thus is expensive to be implemented in practice. The range-free localization algorithm reduces the hardware cost. Because of the hardware limitations of WSN devices, solutions in range-free localization are being pursued as a cost-effective alternative to more expensive range-based approaches. However, these techniques usually have higher localization error compared to the range-based algorithms. DV-Hop is a typical range-free localization algorithm utilizing hop-distance estimation. In this paper, we propose an improved DV-Hop algorithm based on genetic algorithm. Simulation results show that our proposed algorithm improves the localization accuracy compared with previous algorithms.

  11. A Systematic Approach to Local Area Network Administration

    Science.gov (United States)

    1989-03-01

    1988 10:49pm HELP BAT 1152 Apr 19, 1988 09:04pmro~ ort lJjame D> Cop =Typ e LEL0 ~L ]~~~o The 1 DIR Version 3.50 - Copyright (c) Bourbaki , Inc. 1984...1989 01:llpm The 1 DIR Version 3.50 - Copyright (c) Bourbaki , Inc. 1984, 1985 45 3. 3COM NETWORK D:\\APPS\\DBASE3P IDIR SCREEN \\APPS\\DBASE3P iveD Name... Bourbaki , Inc. 1984, 1985 4. TOKEN RING NETWORK BATCH FILE DIRECTORY Drive D Name Ext Size Statistics Toggles Select=> IDIR COM 49823 Disk Usage Optons

  12. Computationally efficient locally-recurrent neural networks for online signal processing

    CERN Document Server

    Hussain, A; Shim, I

    1999-01-01

    A general class of computationally efficient locally recurrent networks (CERN) is described for real-time adaptive signal processing. The structure of the CERN is based on linear-in-the- parameters single-hidden-layered feedforward neural networks such as the radial basis function (RBF) network, the Volterra neural network (VNN) and the functionally expanded neural network (FENN), adapted to employ local output feedback. The corresponding learning algorithms are derived and key structural and computational complexity comparisons are made between the CERN and conventional recurrent neural networks. Two case studies are performed involving the real- time adaptive nonlinear prediction of real-world chaotic, highly non- stationary laser time series and an actual speech signal, which show that a recurrent FENN based adaptive CERN predictor can significantly outperform the corresponding feedforward FENN and conventionally employed linear adaptive filtering models. (13 refs).

  13. An improved local immunization strategy for scale-free networks with a high degree of clustering

    Science.gov (United States)

    Xia, Lingling; Jiang, Guoping; Song, Yurong; Song, Bo

    2017-01-01

    The design of immunization strategies is an extremely important issue for disease or computer virus control and prevention. In this paper, we propose an improved local immunization strategy based on node's clustering which was seldom considered in the existing immunization strategies. The main aim of the proposed strategy is to iteratively immunize the node which has a high connectivity and a low clustering coefficient. To validate the effectiveness of our strategy, we compare it with two typical local immunization strategies on both real and artificial networks with a high degree of clustering. Simulations on these networks demonstrate that the performance of our strategy is superior to that of two typical strategies. The proposed strategy can be regarded as a compromise between computational complexity and immune effect, which can be widely applied in scale-free networks of high clustering, such as social network, technological networks and so on. In addition, this study provides useful hints for designing optimal immunization strategy for specific network.

  14. A Wide Band Strong Acoustic Absorption in a Locally Network Anechoic Coating

    Institute of Scientific and Technical Information of China (English)

    JIANG Heng; ZHANG Mi-Lin; WANG Yu-Ren; HU Yan-Ping; LAN Ding; WEI Bing-Chen

    2009-01-01

    Composite materials with interpenetrating network structures usually exhibit unexpected merit due to the cooperative interaction.Locally resonant phononic crystals (LRPC) exhibit excellent sound attenuation performance based on a periodical arrangement of sound wave scatters.Inspired by the interpenetrating network structure and the LRPC concept, we develop a locally network anechoic coating (LNAC) that can achieve a wide band of underwater strong acoustic absorption.The experimental results show that the LNAC possesses an excellent underwater acoustic absorbing capacity in a wide frequency range.Moreover, in order to investigate the impact of the interpenetrating network structure, we fabricate a faultage structure sample and the network is disconnected by hard polyurethane (PU).The experimental comparison between the LNAC and the faultage structure sample shows that the interpenetrating network structure of the LNAC plays an important role in achieving a wide band strong acoustic absorption.

  15. Formal Description and Verification of a Transport Protocol for Local Networks

    Institute of Scientific and Technical Information of China (English)

    李腊元

    1990-01-01

    This paper discusses a transport protocol and its formal description techniques for local network.The transport layer function,The transport services and a transport protocol design in a local network architecture model are presente.A transport protocol specification using the finite state automate(FSA)is given.The correcness of the protocol is verified by using the reachability tree technique with respect to the protocol properties of completeness.deadlock and livelock freeness,termination and reachability.

  16. Heterogeneity of Global and Local Connectivity in Spatial Network Structures of World Migration

    OpenAIRE

    2016-01-01

    We examine world migration as a social-spatial network of countries connected via movements of people. We assess how multilateral migratory relationships at global, regional, and local scales coexist ("glocalization"), divide ("polarization"), or form an interconnected global system ("globalization"). To do this, we decompose the world migration network (WMN) into communities---sets of countries with denser than expected migration connections---and characterize their pattern of local (i.e., i...

  17. A Wireless Sensor Network with Soft Computing Localization Techniques for Track Cycling Applications

    OpenAIRE

    2016-01-01

    In this paper, we propose two soft computing localization techniques for wireless sensor networks (WSNs). The two techniques, Neural Fuzzy Inference System (ANFIS) and Artificial Neural Network (ANN), focus on a range-based localization method which relies on the measurement of the received signal strength indicator (RSSI) from the three ZigBee anchor nodes distributed throughout the track cycling field. The soft computing techniques aim to estimate the distance between bicycles moving on the...

  18. Sensor selection for received signal strength-based source localization in wireless sensor networks

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Generally, localization is a nonlinear problem, while linearization is used to simplify this problem. Reasonable approximations could be achieved when signal-to-noise ratio (SNR) is large enough. Energy is a critical resource in wireless sensor networks, and system lifetime needs to be prolonged through the use of energy efficient strategies during system operation. In this paper, a closed-form solution for received signal strength (RSS)-based source localization in wireless sensor network (WSN) is obtained...

  19. Pushing the Limits of Indoor Localization in Today’s Wi-Fi Networks

    OpenAIRE

    XIONG, J.

    2015-01-01

    Wireless networks are ubiquitous nowadays and play an increasingly important role in our everyday lives. Many emerging applications including augmented reality, indoor navigation and human tracking, rely heavily on Wi-Fi, thus requiring an even more sophisticated network. One key component for the success of these applications is accurate localization. While we have GPS in the outdoor environment, indoor localization at a sub-meter granularity remains challenging due to a number of factors, i...

  20. Calibration and Validation of the National Ecological Observatory Network's Airborne Imaging Spectrometers

    Science.gov (United States)

    Leisso, N.

    2015-12-01

    The National Ecological Observatory Network (NEON) is being constructed by the National Science Foundation and is slated for completion in 2017. NEON is designed to collect data to improve the understanding of changes in observed ecosystems. The observatory will produce data products on a variety of spatial and temporal scales collected from individual sites strategically located across the U.S. including Alaska, Hawaii, and Puerto Rico. Data sources include standardized terrestrial, instrumental, and aquatic observation systems in addition to three airborne remote sensing observation systems installed into leased Twin Otter aircraft. The Airborne Observation Platforms (AOP) are designed to collect 3-band aerial imagery, waveform and discrete LiDAR, and high-fidelity imaging spectroscopy data over the NEON sites annually at or near peak-greenness. The NEON Imaging Spectrometer (NIS) is a Visible and Shortwave Infrared (VSWIR) sensor designed by NASA JPL for ecological applications. Spectroscopic data is collected at 5-nm intervals across the solar-reflective spectral region (380-nm to 2500-nm) in a 34-degree FOV swath. A key uncertainty driver to the derived remote sensing NEON data products is the calibration of the imaging spectrometers. In addition, the calibration and accuracy of the higher-level data product algorithms is essential to the overall NEON mission to detect changes in the collected ecosystems over the 30-year expected lifetime. The typical calibration workflow of the NIS consists of the characterizing the focal plane, spectral calibration, and radiometric calibration. Laboratory spectral calibration is based on well-defined emission lines in conjunction with a scanning monochromator to define the individual spectral response functions. The radiometric calibration is NIST traceable and transferred to the NIS with an integrating sphere calibrated through the use of transfer radiometers. The laboratory calibration is monitored and maintained through