Analysis of a Wireless Sensors Dropping Problem in Environmental Monitoring

In this paper we study the following problem: we are given a certain region R to monitor and a requirement on the degree of coverage (DoC) of R to meet by a network of deployed sensors. The latter will be dropped by a moving vehicle, which can release sensors at arbitrary points within R. The node spatial distribution when sensors are dropped at a certain points is modeled by a certain probability density function F. The network designer is allowed to choose an arbitrary set of drop points, and to release an arbitrary number of sensors at each point. Given this setting, we consider the problem of determining the optimal deployment strategy, i.e., the drop strategy such that the DoC requirement is fulfilled and the total number of deployed nodes n is minimum. We study this problem both analytically and through simulation, under the assumption that F is the two-dimensional Normal distribution of parameter s (sigma) centered at the drop point. We show that, for given value of s (sigma) and DoC requirement, optimal deployment strategies can be easly identified. The sensor dropping problem studied in this paper is relvant whenever manual node deployment is impossible or overly expensive, and partially controlled deployment (the network designer can choose the drop points, but the final node deployment is random) is the only feasible choice

Direct vs 2-stage approaches to structured motif finding

BACKGROUND: The notion of DNA motif is a mathematical abstraction used to model regions of the DNA (known as Transcription Factor Binding Sites, or TFBSs) that are bound by a given Transcription Factor to regulate gene expression or repression. In turn, DNA structured motifs are a mathematical counterpart that models sets of TFBSs that work in concert in the gene regulations processes of higher eukaryotic organisms. Typically, a structured motif is composed of an ordered set of isolated (or simple) motifs, separated by a variable, but somewhat constrained number of “irrelevant” base-pairs. Discovering structured motifs in a set of DNA sequences is a computationally hard problem that has been addressed by a number of authors using either a direct approach, or via the preliminary identification and successive combination of simple motifs. RESULTS: We describe a computational tool, named SISMA, for the de-novo discovery of structured motifs in a set of DNA sequences. SISMA is an exact, enumerative algorithm, meaning that it finds all the motifs conforming to the specifications. It does so in two stages: first it discovers all the possible component simple motifs, then combines them in a way that respects the given constraints. We developed SISMA mainly with the aim of understanding the potential benefits of such a 2-stage approach w.r.t. direct methods. In fact, no 2-stage software was available for the general problem of structured motif discovery, but only a few tools that solved restricted versions of the problem. We evaluated SISMA against other published tools on a comprehensive benchmark made of both synthetic and real biological datasets. In a significant number of cases, SISMA outperformed the competitors, exhibiting a good performance also in most of the cases in which it was inferior. CONCLUSIONS: A reflection on the results obtained lead us to conclude that a 2-stage approach can be implemented with many advantages over direct approaches. Some of these have to do with greater modularity, ease of parallelization, and the possibility to perform adaptive searches of structured motifs. As another consideration, we noted that most hard instances for SISMA were easy to detect in advance. In these cases one may initially opt for a direct method; or, as a viable alternative in most laboratories, one could run both direct and 2-stage tools in parallel, halting the computations when the first halts

A Semantic-Based Framework for Summarization and Page Segmentation in Web Mining

This chapter addresses two crucial issues that arise when one applies Web-mining techniques for extracting relevant information. The first one is the acquisition of useful knowledge from textual data; the second issue stems from the fact that a web page often proposes a considerable amount of \u2018noise\u2019 with respect to the sections that are truly informative for the user's purposes. The novelty contribution of this work lies in a framework that can tackle both these tasks at the same time, supporting text summarization and page segmentation. The approach achieves this goal by exploiting semantic networks to map natural language into an abstract representation, which eventually supports the identification of the topics addressed in a text source. A heuristic algorithm uses the abstract representation to highlight the relevant segments of text in the original document. The verification of the approach effectiveness involved a publicly available benchmark, the DUC 2002 dataset, and satisfactory results confirmed the method effectiveness

Comparison of a Cell-Based Energy Conservation Techniqueand MST Topology Control in Wireless Ad Hoc Networks

Cooperative strategies and topology control protocols have been recently proposed as effective techniques to reduce energy consumption in wireless ad hoc networks. Although these approaches share the same goal of extending network lifetime, they can be considered as orthogonal approaches

k-NEIGHLEV: a Practical Realization of Neighborhood-Based Topology Control in Ad Hoc Networks

Neighborhood-based topology control has been proven to be very effective in reducing energy consumption and increasing network capacity in ad hoc networks. In this paper, we present a practical realization of this approach that does not rely on distance estimation. Instead, the protocols presented in this paper leverage a feature typical of current wireless cards, namely that discrete power levels can be used for transmission. Ours are the first discrete-power-level protocols that do not require changing the power level on a per-packet basis. We demonstrate, through simulation, that the excellent performance of neighborhood-based topology control is maintained in this more practical setting. We also show that significant energy savings can be obtained if the power levels are optimized for topology control, rather than chosen in an ad hoc manner. Finally, we extend our approach to provide a neighborhood-based topology control protocol that is suitable for mobile networks

H.264 sensor aided video encoder for UAV BLOS missions

This paper presents a new low-complexity H.264 encoder, based on x264 implementation, for Unmanned Aerial Vehicles (UAV) applications. The encoder employs a new motion estimation scheme which make use of the global motion information provided by the onboard navigation system. The results are relevant in low frame rate video coding, which is a typical scenario in UAV behind line-of-sight (BLOS) missions

Pathobiologic roles of epstein–barr virus-encoded microRNAs in human lymphomas

Epstein–Barr virus (EBV) is a human γ-herpesvirus implicated in several human malignancies, including a wide range of lymphomas. Several molecules encoded by EBV in its latent state are believed to be related to EBV-induced lymphomagenesis, among which microRNAs—small RNAs with a posttranscriptional regulating role—are of great importance. The genome of EBV encodes 44 mature microRNAs belonging to two different classes, including BamHI-A rightward transcript (BART) and Bam HI fragment H rightward open reading frame 1 (BHRF1), with different expression levels in different EBV latency types. These microRNAs might contribute to the pathogenetic effects exerted by EBV through targeting self mRNAs and host mRNAs and interfering with several important cellular mechanisms such as immunosurveillance, cell proliferation, and apoptosis. In addition, EBV microRNAs can regulate the surrounding microenvironment of the infected cells through exosomal transportation. Moreover, these small molecules could be potentially used as molecular markers. In this review, we try to present an updated and extensive view of the role of EBV-encoded miRNAs in human lymphomas

Методи пом'якшення

The section describes mitigation methods.У розділі описано методи помякшення