284 research outputs found

    Coaxial cable connector

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    A coaxial cable connector is provided, which resists radio frequency breakdown in coaxial cables used in the vacuum of outer space. The connector body surrounds an insulator which includes an easily compressible elastomeric portion. An insulated coaxial cable is prepared so that its insulation projects beyond the outer conductor and compresses the elastomeric portion of the connector insulator

    Spatial Guilds in the Serengeti Food Web Revealed by a Bayesian Group Model

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    Food webs, networks of feeding relationships among organisms, provide fundamental insights into mechanisms that determine ecosystem stability and persistence. Despite long-standing interest in the compartmental structure of food webs, past network analyses of food webs have been constrained by a standard definition of compartments, or modules, that requires many links within compartments and few links between them. Empirical analyses have been further limited by low-resolution data for primary producers. In this paper, we present a Bayesian computational method for identifying group structure in food webs using a flexible definition of a group that can describe both functional roles and standard compartments. The Serengeti ecosystem provides an opportunity to examine structure in a newly compiled food web that includes species-level resolution among plants, allowing us to address whether groups in the food web correspond to tightly-connected compartments or functional groups, and whether network structure reflects spatial or trophic organization, or a combination of the two. We have compiled the major mammalian and plant components of the Serengeti food web from published literature, and we infer its group structure using our method. We find that network structure corresponds to spatially distinct plant groups coupled at higher trophic levels by groups of herbivores, which are in turn coupled by carnivore groups. Thus the group structure of the Serengeti web represents a mixture of trophic guild structure and spatial patterns, in contrast to the standard compartments typically identified in ecological networks. From data consisting only of nodes and links, the group structure that emerges supports recent ideas on spatial coupling and energy channels in ecosystems that have been proposed as important for persistence.Comment: 28 pages, 6 figures (+ 3 supporting), 2 tables (+ 4 supporting

    Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser.

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    G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology

    Virus genomes reveal factors that spread and sustained the Ebola epidemic.

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    The 2013-2016 West African epidemic caused by the Ebola virus was of unprecedented magnitude, duration and impact. Here we reconstruct the dispersal, proliferation and decline of Ebola virus throughout the region by analysing 1,610 Ebola virus genomes, which represent over 5% of the known cases. We test the association of geography, climate and demography with viral movement among administrative regions, inferring a classic 'gravity' model, with intense dispersal between larger and closer populations. Despite attenuation of international dispersal after border closures, cross-border transmission had already sown the seeds for an international epidemic, rendering these measures ineffective at curbing the epidemic. We address why the epidemic did not spread into neighbouring countries, showing that these countries were susceptible to substantial outbreaks but at lower risk of introductions. Finally, we reveal that this large epidemic was a heterogeneous and spatially dissociated collection of transmission clusters of varying size, duration and connectivity. These insights will help to inform interventions in future epidemics

    Municipal Corporations, Homeowners, and the Benefit View of the Property Tax

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    Panel Discussion

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    Panelists’ Bio and Photo Links: Denise Ammaccapane, Sodexo MJ Caro, Embry-Riddle Aeronautical University – DB Bill Hampton, Embry-Riddle Aeronautical University – DB Frederic Ndaiye, Embry-Riddle Aeronautical University – WW Andre Prescott, Embry-Riddle Aeronautical University – DB Paula Reed, Embry-Riddle Aeronautical University – DB Ed Trombly, Embry-Riddle Aeronautical University – WW Becky Vasquez, Embry-Riddle Aeronautical University – DB Moderated by Marc Bernie

    Panel Discussion

    No full text
    Panelists’ Bio and Photo Links: Denise Ammaccapane, Sodexo MJ Caro, Embry-Riddle Aeronautical University – DB Bill Hampton, Embry-Riddle Aeronautical University – DB Frederic Ndaiye, Embry-Riddle Aeronautical University – WW Andre Prescott, Embry-Riddle Aeronautical University – DB Paula Reed, Embry-Riddle Aeronautical University – DB Ed Trombly, Embry-Riddle Aeronautical University – WW Becky Vasquez, Embry-Riddle Aeronautical University – DB Moderated by Marc Bernie

    Panel Discussion

    No full text
    Panelists’ Bio and Photo Links: Denise Ammaccapane, Sodexo MJ Caro, Embry-Riddle Aeronautical University – DB Bill Hampton, Embry-Riddle Aeronautical University – DB Frederic Ndaiye, Embry-Riddle Aeronautical University – WW Andre Prescott, Embry-Riddle Aeronautical University – DB Paula Reed, Embry-Riddle Aeronautical University – DB Ed Trombly, Embry-Riddle Aeronautical University – WW Becky Vasquez, Embry-Riddle Aeronautical University – DB Moderated by Marc Bernie
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