11,659 research outputs found

    Radio-controlled, sound-operated switch

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    Switch presently provides remote control switching, by radio signals, or pollution sampling devices. Can be used for remote weather station interrogation, firing of pyrotechnics, control of dangerous equipment, or control of device in location where it is impractical to run metallic conductors because of time limitations, distance, or terrain

    Passive fetal monitoring sensor

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    An ambulatory, passive sensor for use in a fetal monitoring system is discussed. The invention is comprised of a piezoelectric polymer film, combined with a metallic mounting plate fastened to a belt, and electrically connected to a signal processing unit by means of a shielded cable. The purpose of the sensor is to receive pressure pulses emitted by a fetus inside an expectant mother. Additionally, the monitor will filter out pressure pulses arising from other sources, such as the maternal heart

    Circular Networks from Distorted Metrics

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    Trees have long been used as a graphical representation of species relationships. However complex evolutionary events, such as genetic reassortments or hybrid speciations which occur commonly in viruses, bacteria and plants, do not fit into this elementary framework. Alternatively, various network representations have been developed. Circular networks are a natural generalization of leaf-labeled trees interpreted as split systems, that is, collections of bipartitions over leaf labels corresponding to current species. Although such networks do not explicitly model specific evolutionary events of interest, their straightforward visualization and fast reconstruction have made them a popular exploratory tool to detect network-like evolution in genetic datasets. Standard reconstruction methods for circular networks, such as Neighbor-Net, rely on an associated metric on the species set. Such a metric is first estimated from DNA sequences, which leads to a key difficulty: distantly related sequences produce statistically unreliable estimates. This is problematic for Neighbor-Net as it is based on the popular tree reconstruction method Neighbor-Joining, whose sensitivity to distance estimation errors is well established theoretically. In the tree case, more robust reconstruction methods have been developed using the notion of a distorted metric, which captures the dependence of the error in the distance through a radius of accuracy. Here we design the first circular network reconstruction method based on distorted metrics. Our method is computationally efficient. Moreover, the analysis of its radius of accuracy highlights the important role played by the maximum incompatibility, a measure of the extent to which the network differs from a tree.Comment: Submitte

    Institutional Identity and Self-Esteem among African American Males in College

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    This article explores the relationship between self-esteem and institutional identity among 411 Black male college freshmen. Institutional identity, especially a sense of belonging, did correlate with self-esteem at both Historically Black Colleges and Universities (HBCUs) and Predominately White Institutions (PWIs), though for different reasons

    Out of Africa: A Molecular Perspective on the Introduction of Yellow Fever Virus into the Americas

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    Yellow fever virus (YFV) remains the cause of severe morbidity and mortality in South America and Africa. To determine the evolutionary history of this important reemerging pathogen, we performed a phylogenetic analysis of the largest YFV data set compiled to date, representing the prM/E gene region from 133 viral isolates sampled from 22 countries over a period of 76 years. We estimate that the currently circulating strains of YFV arose in Africa within the last 1,500 years and emerged in the Americas following the slave trade approximately 300–400 years ago. These viruses then spread westwards across the continent and persist there to this day in the jungles of South America. We therefore illustrate how gene sequence data can be used to test hypotheses of viral dispersal and demographics, and document the role of human migration in the spread of infectious disease

    A natural Finsler--Laplace operator

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    We give a new definition of a Laplace operator for Finsler metric as an average with regard to an angle measure of the second directional derivatives. This definition uses a dynamical approach due to Foulon that does not require the use of connections nor local coordinates. We show using 1-parameter families of Katok--Ziller metrics that this Finsler--Laplace operator admits explicit representations and computations of spectral data.Comment: 25 pages, v2: minor modifications, changed the introductio

    Efficient FPT algorithms for (strict) compatibility of unrooted phylogenetic trees

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    In phylogenetics, a central problem is to infer the evolutionary relationships between a set of species XX; these relationships are often depicted via a phylogenetic tree -- a tree having its leaves univocally labeled by elements of XX and without degree-2 nodes -- called the "species tree". One common approach for reconstructing a species tree consists in first constructing several phylogenetic trees from primary data (e.g. DNA sequences originating from some species in XX), and then constructing a single phylogenetic tree maximizing the "concordance" with the input trees. The so-obtained tree is our estimation of the species tree and, when the input trees are defined on overlapping -- but not identical -- sets of labels, is called "supertree". In this paper, we focus on two problems that are central when combining phylogenetic trees into a supertree: the compatibility and the strict compatibility problems for unrooted phylogenetic trees. These problems are strongly related, respectively, to the notions of "containing as a minor" and "containing as a topological minor" in the graph community. Both problems are known to be fixed-parameter tractable in the number of input trees kk, by using their expressibility in Monadic Second Order Logic and a reduction to graphs of bounded treewidth. Motivated by the fact that the dependency on kk of these algorithms is prohibitively large, we give the first explicit dynamic programming algorithms for solving these problems, both running in time 2O(k2)n2^{O(k^2)} \cdot n, where nn is the total size of the input.Comment: 18 pages, 1 figur

    OBDD-Based Representation of Interval Graphs

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    A graph G=(V,E)G = (V,E) can be described by the characteristic function of the edge set χE\chi_E which maps a pair of binary encoded nodes to 1 iff the nodes are adjacent. Using \emph{Ordered Binary Decision Diagrams} (OBDDs) to store χE\chi_E can lead to a (hopefully) compact representation. Given the OBDD as an input, symbolic/implicit OBDD-based graph algorithms can solve optimization problems by mainly using functional operations, e.g. quantification or binary synthesis. While the OBDD representation size can not be small in general, it can be provable small for special graph classes and then also lead to fast algorithms. In this paper, we show that the OBDD size of unit interval graphs is O( V /log V )O(\ | V \ | /\log \ | V \ |) and the OBDD size of interval graphs is $O(\ | V \ | \log \ | V \ |)whichbothimproveaknownresultfromNunkesserandWoelfel(2009).Furthermore,wecanshowthatusingourvariableorderandnodelabelingforintervalgraphstheworstcaseOBDDsizeis which both improve a known result from Nunkesser and Woelfel (2009). Furthermore, we can show that using our variable order and node labeling for interval graphs the worst-case OBDD size is \Omega(\ | V \ | \log \ | V \ |).Weusethestructureoftheadjacencymatricestoprovethesebounds.Thismethodmaybeofindependentinterestandcanbeappliedtoothergraphclasses.Wealsodevelopamaximummatchingalgorithmonunitintervalgraphsusing. We use the structure of the adjacency matrices to prove these bounds. This method may be of independent interest and can be applied to other graph classes. We also develop a maximum matching algorithm on unit interval graphs using O(\log \ | V \ |)operationsandacoloringalgorithmforunitandgeneralintervalsgraphsusing operations and a coloring algorithm for unit and general intervals graphs using O(\log^2 \ | V \ |)$ operations and evaluate the algorithms empirically.Comment: 29 pages, accepted for 39th International Workshop on Graph-Theoretic Concepts 201
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