2,546 research outputs found

    Networking and Application Interface Technology for Wireless Sensor Network Surveillance and Monitoring

    Get PDF
    Distributed unattended ground sensor networks used in battlefield surveillance and monitoring missions, have proven to be valuable in providing a tactical information advantage required for command and control, intelligence, surveillance, and reconnaissance planning. Operational effectiveness for surveillance missions can be enhanced further through network centric capability, where distributed UGS networks have the ability to perform surveillance operations autonomously. NCC operation can be enhanced through UGSs having the ability to evaluate their awareness of the current joint surveillance environment, in order to provide the necessary adaptation to dynamic changes. NCC can also provide an advantage for UGS networks to self-manage their limited operational resources efficiently, according to mission objective priority. In this article, we present a cross-layer approach and highlight techniques that have potential to enable NCC operation within a mission-orientated UGS surveillance setting

    Network conduciveness with application to the graph-coloring and independent-set optimization transitions

    Full text link
    We introduce the notion of a network's conduciveness, a probabilistically interpretable measure of how the network's structure allows it to be conducive to roaming agents, in certain conditions, from one portion of the network to another. We exemplify its use through an application to the two problems in combinatorial optimization that, given an undirected graph, ask that its so-called chromatic and independence numbers be found. Though NP-hard, when solved on sequences of expanding random graphs there appear marked transitions at which optimal solutions can be obtained substantially more easily than right before them. We demonstrate that these phenomena can be understood by resorting to the network that represents the solution space of the problems for each graph and examining its conduciveness between the non-optimal solutions and the optimal ones. At the said transitions, this network becomes strikingly more conducive in the direction of the optimal solutions than it was just before them, while at the same time becoming less conducive in the opposite direction. We believe that, besides becoming useful also in other areas in which network theory has a role to play, network conduciveness may become instrumental in helping clarify further issues related to NP-hardness that remain poorly understood

    Most vital segment barriers

    Get PDF
    We study continuous analogues of "vitality" for discrete network flows/paths, and consider problems related to placing segment barriers that have highest impact on a flow/path in a polygonal domain. This extends the graph-theoretic notion of "most vital arcs" for flows/paths to geometric environments. We give hardness results and efficient algorithms for various versions of the problem, (almost) completely separating hard and polynomially-solvable cases

    VIGILANT: "Situation-Aware" Quality of Information Interest Groups for Wireless Sensor Network Surveillance Applications

    Get PDF
    Effective situation awareness is a critical element for decision support in a wide range of military and para-military operational surveillance scenarios. Effective situation awareness in a surveillance scenario can greatly increase operational effectiveness, by improving the quality and timeliness of decisions. In this paper we outline a three level integrated design approach to promote situation awareness. Our approach allows deployed wireless sensor nodes to efficiently self-organise into dynamic clusters, based on a current common perceived threat situation ( context). Firstly our distributed predator aware situation assessment system ( PORTENT) models, detects and presents, in terms of quality of information (QoI), potential situations occurring within an uncertain environment. Secondly, we utilise a Bayesian belief network to understand the significance associated with the potential situation. Finally in order to obtain a better shared awareness we have developed a "context aware" service protocol that supports group formation and efficient management of sensor network assets. By combining this three level approach, we present our VIGILANT "situation aware" QoI interest group system. Extensive simulations have been undertaken to verify the VIGILANT concept, to demonstrate the effectiveness of our approach, in improving performance for network management efficiency, through utilisation of a shared "context" service provision time and QoI surveillance presentation

    Piloting a parent and patient decision aid to support clinical trial decision making in childhood cancer

    Full text link
    Objective: Families of a child with cancer can find the decision to enrol in a clinical trial challenging and often misunderstand key concepts that underpin trials. We pilot tested “Delta,” an online and booklet decision aid for parents with a child with cancer, and adolescents with cancer, deciding whether or not to enrol in a clinical trial. Methods: We developed Delta in accordance with the International Patient Decision Aid Standards. We conducted a pre-post pilot with parents with a child, and adolescents, who had enrolled in a paediatric phase III clinical trial for newly diagnosed acute lymphoblastic leukaemia. Parents (n = 37) and adolescents (n = 3) completed a questionnaire before and after using Delta (either the website or booklet, based on their preference). Results: Twenty-three parents (62.2%) and three adolescents (100%) reviewed the Delta website. Parents rated Delta as highly acceptable in regard to being clearly presented, informative, easy to read, useful, visually appealing, and easy to use. All participants reported that they would recommend Delta to others and that it would have been useful when making their decision. Parents' subjective (Mdiff=10.8, SDdiff = 15.69, P <.001) and objective (OR = 2.25, 95% CI, 1.66-3.04; P <.001) clinical trial knowledge increased significantly after reviewing Delta. Conclusions: To our knowledge, Delta is the first reported decision aid, available online and as a booklet, for parents and adolescents deciding whether or not to enrol in a paediatric oncology clinical trial. Our study suggests that Delta is acceptable, feasible, and potentially useful

    Enhanced flow-motion complexity of skin microvascular perfusion in Sherpas and lowlanders during ascent to high altitude

    Get PDF
    An increased and more effective microvascular perfusion is postulated to play a key role in the physiological adaptation of Sherpa highlanders to the hypobaric hypoxia encountered at high altitude. To investigate this, we used Lempel-Ziv complexity (LZC) analysis to explore the spatiotemporal dynamics of the variability of the skin microvascular blood flux (BF) signals measured at the forearm and finger, in 32 lowlanders (LL) and 46 Sherpa highlanders (SH) during the Xtreme Everest 2 expedition. Measurements were made at baseline (BL) (LL: London 35 m; SH: Kathmandu 1300 m) and at Everest base camp (LL and SH: EBC 5,300 m). We found that BF signal content increased with ascent to EBC in both SH and LL. At both altitudes, LZC of the BF signals was significantly higher in SH, and was related to local slow-wave flow-motion activity over multiple spatial and temporal scales. In SH, BF LZC was also positively associated with LZC of the simultaneously measured tissue oxygenation signals. These data provide robust mechanistic information of microvascular network functionality and flexibility during hypoxic exposure on ascent to high altitude. They demonstrate the importance of a sustained heterogeneity of network perfusion, associated with local vaso-control mechanisms, to effective tissue oxygenation during hypobaric hypoxia

    Online Sexual Partner Seeking as a Social Practice: Qualitative Evidence from the 4(th) British National Survey of Sexual Attitudes and Lifestyles (Natsal-4)

    Get PDF
    Once perceived as a means for those unsuccessful at traditional dating, online dating has become normalized as a way to seek sexual or romantic partners. In 2019, we interviewed 40 British adults on the role of digital technologies in their sexual lives; this paper draws on the accounts of 22 who had used such technologies for seeking partners. We analyzed qualitative accounts of online partner seeking as a social practice, drawing on a sample diverse in age, gender and sexual orientation, and informed by sexual script and social practice theory. Our theoretically informed analysis emphasized the multiple meanings and goals involved, the affordances of the technology and individuals’ skills. Our study provided several novel contributions. Young heterosexual people commonly used general social media, rather than dating apps, to meet partners; meeting partners often involved complex interplays between online and offline networks and encounters. Risks were defined not merely in relation to “risky others” but in terms of one’s own actions or attitudes. Participants deployed various skills in minimizing harms such as non-consensual sharing of intimate images, and used self-care skills such as setting limits to engagement

    Travelling on Graphs with Small Highway Dimension

    Get PDF
    We study the Travelling Salesperson (TSP) and the Steiner Tree problem (STP) in graphs of low highway dimension. This graph parameter was introduced by Abraham et al. [SODA 2010] as a model for transportation networks, on which TSP and STP naturally occur for various applications in logistics. It was previously shown [Feldmann et al. ICALP 2015] that these problems admit a quasi-polynomial time approximation scheme (QPTAS) on graphs of constant highway dimension. We demonstrate that a significant improvement is possible in the special case when the highway dimension is 1, for which we present a fully-polynomial time approximation scheme (FPTAS). We also prove that STP is weakly NP-hard for these restricted graphs. For TSP we show NP-hardness for graphs of highway dimension 6, which answers an open problem posed in [Feldmann et al. ICALP 2015]

    A dynamic network approach for the study of human phenotypes

    Get PDF
    The use of networks to integrate different genetic, proteomic, and metabolic datasets has been proposed as a viable path toward elucidating the origins of specific diseases. Here we introduce a new phenotypic database summarizing correlations obtained from the disease history of more than 30 million patients in a Phenotypic Disease Network (PDN). We present evidence that the structure of the PDN is relevant to the understanding of illness progression by showing that (1) patients develop diseases close in the network to those they already have; (2) the progression of disease along the links of the network is different for patients of different genders and ethnicities; (3) patients diagnosed with diseases which are more highly connected in the PDN tend to die sooner than those affected by less connected diseases; and (4) diseases that tend to be preceded by others in the PDN tend to be more connected than diseases that precede other illnesses, and are associated with higher degrees of mortality. Our findings show that disease progression can be represented and studied using network methods, offering the potential to enhance our understanding of the origin and evolution of human diseases. The dataset introduced here, released concurrently with this publication, represents the largest relational phenotypic resource publicly available to the research community.Comment: 28 pages (double space), 6 figure
    • …
    corecore