379 research outputs found

    Equity of African American Men in Headache in the United States: A Perspective From African American Headache Medicine Specialists (Part 1)

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163649/2/head14004.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163649/1/head14004_am.pd

    Architecture, Design, Simulation and Performance Evaluation for Implementing ALAX -- The ATM LAN Access Switch Integrating the IEEE 1355 Serial Bus

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    IEEE 1355 is a serial bus standard for Heterogeneous Inter Connect (HIC) developed for "enabling high-performance, scalable, modular and parallel systems to be built with low system integration cost." However to date, few systems have been built around this standard specification. In this thesis, we propose ALAX -- an internetworking switching device based on IEEE 1355. The aim of the thesis is two-fold. First, we discuss and summarize research works leading to the architecture, design and simulation development for ALAX; we synthesize and analyze relevant data collected from the simulation experiments of the 4- port model of ALAX (i.e., 4-by-4 with four input and output queues) -- these activities were conducted during the 2-year length of the project. Secondly, we expand the original 4-by-4 size of the ALAX simulation model into 8-, 12- and 16-port models and present and interpret the outcomes. Thus, overall we establish a performance assessment of the ALAX switch, and also identify several critical design measurements to support the ALAX prototype implementation. We review progresses made in Local Area Networks (LANs) where traditional software-enabled bridges or routers are being replaced in many instances by hardware-enabled switches to enhance network performance. Within that context, ATM (Asynchronous Transfer Mode) technology emerges as an alternative for the next generation of high-speed LANs. Hence, ALAX incarnates our effective approach to build an ATM-LAN interface using a suitable switching platform. ALAX currently provides the capability to conveniently interconnect legacy Ethernet and ATM- based networks. Its distributed architecture features a multi- processor environment of T9000 transputers with parallel processing capability, a 32-by-32 way non-blocking crossbar fabric (C104 chipset) partitioned into Transport (i.e., Data) and Control planes, and many other modules interlaced with IEEE 1355- based connectors. It also employs existing and emerging protocols such as LANE (LAN Emulation), IEEE 802.3 and SNMP (Simple Network Management Protocol). We provide the component breakdown of the ALAX simulation model based on Optimized Network Engineering Tools (OPNET). The critical parameters for the study are acceptable processor speeds and queuing sizes of shared memory buffer at each switch port. The performance metric used is the end-to-end packet delay. Finally, we end the thesis with conclusive recommendations pertaining to performance and design measurement, and a brief summary of areas for further research study

    Evidence of widespread selection on standing variation in Europe at height-associated SNPs.

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    Strong signatures of positive selection at newly arising genetic variants are well documented in humans(1-8), but this form of selection may not be widespread in recent human evolution(9). Because many human traits are highly polygenic and partly determined by common, ancient genetic variation, an alternative model for rapid genetic adaptation has been proposed: weak selection acting on many pre-existing (standing) genetic variants, or polygenic adaptation(10-12). By studying height, a classic polygenic trait, we demonstrate the first human signature of widespread selection on standing variation. We show that frequencies of alleles associated with increased height, both at known loci and genome wide, are systematically elevated in Northern Europeans compared with Southern Europeans (P < 4.3 × 10(-4)). This pattern mirrors intra-European height differences and is not confounded by ancestry or other ascertainment biases. The systematic frequency differences are consistent with the presence of widespread weak selection (selection coefficients ∼10(-3)-10(-5) per allele) rather than genetic drift alone (P < 10(-15))

    Unifying Parsimonious Tree Reconciliation

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    Evolution is a process that is influenced by various environmental factors, e.g. the interactions between different species, genes, and biogeographical properties. Hence, it is interesting to study the combined evolutionary history of multiple species, their genes, and the environment they live in. A common approach to address this research problem is to describe each individual evolution as a phylogenetic tree and construct a tree reconciliation which is parsimonious with respect to a given event model. Unfortunately, most of the previous approaches are designed only either for host-parasite systems, for gene tree/species tree reconciliation, or biogeography. Hence, a method is desirable, which addresses the general problem of mapping phylogenetic trees and covering all varieties of coevolving systems, including e.g., predator-prey and symbiotic relationships. To overcome this gap, we introduce a generalized cophylogenetic event model considering the combinatorial complete set of local coevolutionary events. We give a dynamic programming based heuristic for solving the maximum parsimony reconciliation problem in time O(n^2), for two phylogenies each with at most n leaves. Furthermore, we present an exact branch-and-bound algorithm which uses the results from the dynamic programming heuristic for discarding partial reconciliations. The approach has been implemented as a Java application which is freely available from http://pacosy.informatik.uni-leipzig.de/coresym.Comment: Peer-reviewed and presented as part of the 13th Workshop on Algorithms in Bioinformatics (WABI2013

    Effect of Plant Species on the Development and Vertical Migration of Larvae of Gastrointestinal Nematodes which Parasitise Sheep

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    The development and migration of gastrointestinal nematode larvae on a range of herbage species were compared following a series of standardised contaminations with sheep faeces over two years. In 1992/93, greatest numbers of larvae were recovered from browntop (Agrostis capillaris cv Grasslands Muster), cocksfoot (Dactylis glomerata cv Grasslands Kara), ryegrass (Lolium perenne cv Grasslands Nui) and Yorkshire fog (Holcus lanatus cv Massey Basyn) while the lowest numbers were recovered from white clover (Trifolium repens cv Grasslands Huia) with the other herbages intermediate. In 1993/94, highest numbers were recovered from Yorkshire fog and ryegrass, lowest numbers from white clover, chicory (Chicorium intybus cv Grasslands Puna) and lucerne (Medicago sativa cv Grasslands Otaio) and intermediate from the other herbages. The proportions of total larvae recovered in the 0- 2.5 cm stratum, an inverse measure of larval migration, were lowest in white clover, ryegrass, tall fescue (Festuca arundinacea cv Au Triumph) and browntop, highest for Yorkshire fog and intermediate for the other grasses
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