284 research outputs found
Coaxial cable connector
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
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.
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
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High throughput instruments, methods, and informatics for systems biology.
High throughput instruments and analysis techniques are required in order to make good use of the genomic sequences that have recently become available for many species, including humans. These instruments and methods must work with tens of thousands of genes simultaneously, and must be able to identify the small subsets of those genes that are implicated in the observed phenotypes, or, for instance, in responses to therapies. Microarrays represent one such high throughput method, which continue to find increasingly broad application. This project has improved microarray technology in several important areas. First, we developed the hyperspectral scanner, which has discovered and diagnosed numerous flaws in techniques broadly employed by microarray researchers. Second, we used a series of statistically designed experiments to identify and correct errors in our microarray data to dramatically improve the accuracy, precision, and repeatability of the microarray gene expression data. Third, our research developed new informatics techniques to identify genes with significantly different expression levels. Finally, natural language processing techniques were applied to improve our ability to make use of online literature annotating the important genes. In combination, this research has improved the reliability and precision of laboratory methods and instruments, while also enabling substantially faster analysis and discovery
Virus genomes reveal factors that spread and sustained the Ebola epidemic.
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
Panel Discussion
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
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
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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