75,716 research outputs found
Conceptual design for the Space Station Freedom fluid physics/dynamics facility
A study team at NASA's Lewis Research Center has been working on a definition study and conceptual design for a fluid physics and dynamics science facility that will be located in the Space Station Freedom's baseline U.S. Laboratory module. This modular, user-friendly facility, called the Fluid Physics/Dynamics Facility, will be available for use by industry, academic, and government research communities in the late 1990's. The Facility will support research experiments dealing with the study of fluid physics and dynamics phenomena. Because of the lack of gravity-induced convection, research into the mechanisms of fluids in the absence of gravity will help to provide a better understanding of the fundamentals of fluid processes. This document has been prepared as a final version of the handout for reviewers at the Fluid Physics/Dynamics Facility Assessment Workshop held at Lewis on January 24 and 25, 1990. It covers the background, current status, and future activities of the Lewis Project Study Team effort. It is a revised and updated version of a document entitled 'Status Report on the Conceptual Design for the Space Station Fluid Physics/Dynamics Facility', dated January 1990
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Coordinative Entities: Forms of Organizing in Data Intensive Science
Scientific collaboration is a long-standing subject of CSCW scholarship that typically focuses on the development and use of computing systems to facilitate research. The research presented in this article investigates the sociality of science by identifying and describing particular, common forms of organizing that researchers in four different scientific realms employ to conduct work in both local contexts and as part of distributed, global projects. This paper introduces five prototypical forms of organizing we categorize as coordinative entities: the Principal Group, Intermittent Exchange, Sustained Aggregation, Federation, and Facility Organization. Coordinative entities as a categorization help specify, articulate, compare, and trace overlapping and evolving arrangements scientists use to facilitate data intensive research. We use this typology to unpack complexities of data intensive scientific collaboration in four cases, showing how scientists invoke different coordinative entities across three types of research activities: data collection, processing, and analysis. Our contribution scrutinizes the sociality of scientific work to illustrate how these actors engage in relational work within and among diverse, dispersed forms of organizing across project, funding, and disciplinary boundaries
A phylogeny of birds based on over 1,500 loci collected by target enrichment and high-throughput sequencing
Evolutionary relationships among birds in Neoaves, the clade comprising the
vast majority of avian diversity, have vexed systematists due to the ancient,
rapid radiation of numerous lineages. We applied a new phylogenomic approach to
resolve relationships in Neoaves using target enrichment (sequence capture) and
high-throughput sequencing of ultraconserved elements (UCEs) in avian genomes.
We collected sequence data from UCE loci for 32 members of Neoaves and one
outgroup (chicken) and analyzed data sets that differed in their amount of
missing data. An alignment of 1,541 loci that allowed missing data was 87%
complete and resulted in a highly resolved phylogeny with broad agreement
between the Bayesian and maximum-likelihood (ML) trees. Although results from
the 100% complete matrix of 416 UCE loci were similar, the Bayesian and ML
trees differed to a greater extent in this analysis, suggesting that increasing
from 416 to 1,541 loci led to increased stability and resolution of the tree.
Novel results of our study include surprisingly close relationships between
phenotypically divergent bird families, such as tropicbirds (Phaethontidae) and
the sunbittern (Eurypygidae) as well as between bustards (Otididae) and turacos
(Musophagidae). This phylogeny bolsters support for monophyletic waterbird and
landbird clades and also strongly supports controversial results from previous
studies, including the sister relationship between passerines and parrots and
the non-monophyly of raptorial birds in the hawk and falcon families. Although
significant challenges remain to fully resolving some of the deep relationships
in Neoaves, especially among lineages outside the waterbirds and landbirds,
this study suggests that increased data will yield an increasingly resolved
avian phylogeny.Comment: 30 pages, 1 table, 4 figures, 1 supplementary table, 3 supplementary
figure
Joint assembly and genetic mapping of the Atlantic horseshoe crab genome reveals ancient whole genome duplication
Horseshoe crabs are marine arthropods with a fossil record extending back
approximately 450 million years. They exhibit remarkable morphological
stability over their long evolutionary history, retaining a number of ancestral
arthropod traits, and are often cited as examples of "living fossils." As
arthropods, they belong to the Ecdysozoa}, an ancient super-phylum whose
sequenced genomes (including insects and nematodes) have thus far shown more
divergence from the ancestral pattern of eumetazoan genome organization than
cnidarians, deuterostomes, and lophotrochozoans. However, much of ecdysozoan
diversity remains unrepresented in comparative genomic analyses. Here we use a
new strategy of combined de novo assembly and genetic mapping to examine the
chromosome-scale genome organization of the Atlantic horseshoe crab Limulus
polyphemus. We constructed a genetic linkage map of this 2.7 Gbp genome by
sequencing the nuclear DNA of 34 wild-collected, full-sibling embryos and their
parents at a mean redundancy of 1.1x per sample. The map includes 84,307
sequence markers and 5,775 candidate conserved protein coding genes. Comparison
to other metazoan genomes shows that the L. polyphemus genome preserves
ancestral bilaterian linkage groups, and that a common ancestor of modern
horseshoe crabs underwent one or more ancient whole genome duplications (WGDs)
~ 300 MYA, followed by extensive chromosome fusion
Patterns for service-oriented information exchange requirements
Service-Oriented Computing (SOC) is an emerging computing paradigm that supports loosely-coupled inter-enterprise interactions. SOC interactions are predominantly specified in a procedural manner that defines message sequences intermixing implementation with business requirements. In this paper we present a set of patterns concerning requirements of information exchange between participants engaging in service-oriented interactions. The patterns aim at explicating and elaborating the business requirements driving the interaction and separating them from implementation concerns
GRAPHICAL CONFIGURATION PROGRAMMING - THE STRUCTURAL DESCRIPTION, CONSTRUCTION AND EVOLUTION OF SOFTWARE SYSTEMS USING GRAPHICS
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Voyager spacecraft phase B, task D. Volume 2 - System description. Book 5 - Final report
Voyager spacecraft design standards, and operational support and mission-dependent equipment requirement
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