39 research outputs found

    A Self-Adaptive Regression-Based Multivariate Data Compression Scheme with Error Bound in Wireless Sensor Networks

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    Wireless sensor networks (WSNs) have limited energy and transmission capacity, so data compression techniques have extensive applications. A sensor node with multiple sensing units is called a multimodal or multivariate node. For multivariate stream on a sensor node, some data streams are elected as the base functions according to the correlation coefficient matrix, and the other streams from the same node can be expressed in relation to one of these base functions using linear regression. By designing an incremental algorithm for computing regression coefficients, a multivariate data compression scheme based on self-adaptive regression with infinite norm error bound for WSNs is proposed. According to error bounds and compression incomes, the self-adaption means that the proposed algorithms make decisions automatically to transmit raw data or regression coefficients, and to select the number of data involved in regression. The algorithms in the scheme can simultaneously explore the temporal and multivariate correlations among the sensory data. Theoretically and experimentally, it is concluded that the proposed algorithms can effectively exploit the correlations on the same sensor node and achieve significant reduction in data transmission. Furthermore, the algorithms perform consistently well even when multivariate stream data correlations are less obvious or non-stationary. </jats:p

    A cardinal role for cathepsin D in co-ordinating the host-mediated apoptosis of macrophages and killing of pneumococci

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    The bactericidal function of macrophages against pneumococci is enhanced by their apoptotic demise, which is controlled by the anti-apoptotic protein Mcl-1. Here, we show that lysosomal membrane permeabilization (LMP) and cytosolic translocation of activated cathepsin D occur prior to activation of a mitochondrial pathway of macrophage apoptosis. Pharmacological inhibition or knockout of cathepsin D during pneumococcal infection blocked macrophage apoptosis. As a result of cathepsin D activation, Mcl-1 interacted with its ubiquitin ligase Mule and expression declined. Inhibition of cathepsin D had no effect on early bacterial killing but inhibited the late phase of apoptosis-associated killing of pneumococci in vitro. Mice bearing a cathepsin D-/- hematopoietic system demonstrated reduced macrophage apoptosis in vivo, with decreased clearance of pneumococci and enhanced recruitment of neutrophils to control pulmonary infection. These findings establish an unexpected role for a cathepsin D-mediated lysosomal pathway of apoptosis in pulmonary host defense and underscore the importance of apoptosis-associated microbial killing to macrophage function

    Local IL-17 Production Exerts a Protective Role in Murine Experimental Glomerulonephritis

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    IL-17 is a pro-inflammatory cytokine implicated in the pathogenesis of glomerulonephritis and IL-17 deficient mice are protected from nephrotoxic nephritis. However, a regulatory role for IL-17 has recently emerged. We describe a novel protective function for IL-17 in the kidney. Bone marrow chimeras were created using wild-type and IL-17 deficient mice and nephrotoxic nephritis was induced. IL-17 deficient hosts transplanted with wild-type bone marrow had worse disease by all indices compared to wild-type to wild-type bone marrow transplants (serum urea p<0.05; glomerular thrombosis p<0.05; tubular damage p<0.01), suggesting that in wild-type mice, IL-17 production by renal cells resistant to radiation is protective. IL-17 deficient mice transplanted with wild-type bone marrow also had a comparatively altered renal phenotype, with significant differences in renal cytokines (IL-10 p<0.01; IL-1β p<0.001; IL-23 p<0.01), and macrophage phenotype (expression of mannose receptor p<0.05; inducible nitric oxide synthase p<0.001). Finally we show that renal mast cells are resistant to radiation and produce IL-17, suggesting they are potential local mediators of disease protection. This is a novel role for intrinsic cells in the kidney that are radio-resistant and produce IL-17 to mediate protection in nephrotoxic nephritis. This has clinical significance as IL-17 blockade is being trialled as a therapeutic strategy in some autoimmune diseases

    A Secure and Scalable Digital Time-stamping Service

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    We propose a distributed digital time--stamping service (TSS) based on absolute timestamps and resilient to Byzantine failures. In contrast with previous solutions based on linking schemes, our TSS provides \emph{high scalability}, \emph{better response time}, and \emph{fine granularity}. It works in asynchronous systems

    A Clustering-Based Approximation Scheme for In-Network Aggregation over Sensor Networks

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    Revising Quorum Systems for Energy Conservation in Sensor Networks

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    Quorum systems are well-known techniques designed to enhance the performance of distributed systems, such as to reduce the access cost per operation, to balance the load, and to improve the system scalability. All of these properties make quorum systems particularly attractive for largescale sensor applications involving coordinated tasks, such as rescue applications. In this paper we analyze quorum techniques in the specific context of sensor networks and energy conservation, and show why quorum systems designed for wired networks and their metrics fail to address the challenges introduced by sensor networks. We then redefine quorum metrics such as access cost, load balance, and capacity in a way that takes into account the limitations and the characteristics of sensor networks, and discuss some energy-efficient design strategies. In addition, we propose a family of energy-efficient quorum systems and a particular construction, called Regional Quorum system (RQ), which reduces the quorum access cost. Finally, we propose a data diffusion protocol built on top of the RQ system, which improves energy consumption by reducing message transmissions and collisions, and increases the available bandwidth. We apply our diffusion protocol to analyze the RQ system using our novel metrics

    Are coastal communities able to pay for the protection of fish resources impacted by climate change?

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    The purpose of this study is to examine inhabitants’ motivation and their willingness to pay to mitigate the impact of climate change on fish resources. Willingness to pay was tested empirically using survey data from 333 inhabitants of Sciacca, a fishing community in Sicily, Italy, which has the island's second largest fishing fleet. People's attitudes towards climate change, their degree of involvement in the issue, and their concerns about this phenomenon's potential impact on the marine environment are the key factors affecting their willingness to pay. It was further found that respondents are willing to pay an average of €6.81 per month to support mitigation policies in the fishing industry. The originality of this study is related to its contribution in expanding the body of knowledge on citizens’ willingness to pay for the protection of fish resources, using a conceptual framework based on the Construal Level Theory and the Theory of Reasoned Action to explain inhabitants’ behaviour. The latter is one of the implications of this study on the theoretical point of view. In addition, this study provides insights and hints to policy makers to define tools, shared by the community, that contribute to the mitigation of climate change

    Prediction-Based Filter Updating Policies for Top- k

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