Electronic Switching Spherical Array (ESSA) antenna systems

ESSA (Electronic Switching Spherical Array) is an antenna system conceived, developed and qualified for linking satellite data transmissions with NASA's tracking and data relay satellites (TDRSS) and tracking and data acquisition satellites (TDAS). ESSA functions in the S band frequency region, cover 2 pi or more steradians with directional gain and operates in multiple selectable modes. ESSA operates in concert with the NASA's TDRS standard transponder in the retrodirective mode or independently in directional beam, program track and special modes. Organizations and projects to the ESSA applications for NASA's space use are introduced. Coverage gain, weight power and implementation and other performance information for satisfying a wide range of data rate requirements are included

Performance interface document for users of Tracking and Data Relay Satellite System (TDRSS) electromechanically steered antenna systems (EMSAS)

Satellites that use the NASA Tracking and Data Relay Satellite System (TDRSS) require antennas that are crucial for performing and achieving reliable TDRSS link performance at the desired data rate. Technical guidelines are presented to assist the prospective TDRSS medium-and high-data rate user in selecting and procuring a viable, steerable high-gain antenna system. Topics addressed include the antenna gain/transmitter power/data rate relationship; Earth power flux-density limitations; electromechanical requirements dictated by the small beam widths, desired angular coverage, and minimal torque disturbance to the spacecraft; weight and moment considerations; mechanical, electrical and thermal interfaces; design lifetime failure modes; and handling and storage. Proven designs are cited and space-qualified assemblies and components are identified

Purification of cross-linked RNA-protein complexes by phenol-toluol extraction

Recent methodological advances allowed the identification of an increasing number of RNA-binding proteins (RBPs) and their RNA-binding sites. Most of those methods rely, however, on capturing proteins associated to polyadenylated RNAs which neglects RBPs bound to non-adenylate RNA classes (tRNA, rRNA, pre-mRNA) as well as the vast majority of species that lack poly-A tails in their mRNAs (including all archea and bacteria). We have developed the Phenol Toluol extraction (PTex) protocol that does not rely on a specific RNA sequence or motif for isolation of cross-linked ribonucleoproteins (RNPs), but rather purifies them based entirely on their physicochemical properties. PTex captures RBPs that bind to RNA as short as 30 nt, RNPs directly from animal tissue and can be used to simplify complex workflows such as PAR-CLIP. Finally, we provide a global RNA-bound proteome of human HEK293 cells and the bacterium Salmonella Typhimurium

A Data Handling and Linking System for all of NASA's Near Earth Space Missions

International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, CaliforniaA modularized data handling and linking system is evolving that will meet all of NASA's low earth orbiting space needs. The system is comprised of three major subsystems: (1) Data management (three networks; 300 Mbps to 20 Mbps, 20 Mbps to 3 Mbps, and 3 Mbps to 125 bps); (2) RF (antennas and microwave components); and (3) antenna control. Representative system components, approximately 70% of a total system, have been tested operating through the NASA Tracking and Data Relay Satellite System in May 1987. The modularized concept and data bandwidth transitions of the data management subsystem utilizes recently developed flight components along with developmental models that results in a system that is cost effective with a high level of performance and reliability. The system concept with performance data of key components will be presented.International Foundation for TelemeteringProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection

Alternative explanation for excision repair deficiency caused by the polAex1 mutation.

An investigation of the mechanism of the polAex1 mutation in vitro suggested that the excision repair deficiency observed in vivo does not result from an inability of the enzyme to nick translate. The defect appears to reside in the inability of the enzyme to effectively generate a nick structure to serve as a substrate for DNA ligase

iCLIP reveals the function of hnRNP particles in splicing at individual nucleotide resolution

In the nucleus of eukaryotic cells, nascent transcripts are associated with heterogeneous nuclear ribonucleoprotein (hnRNP) particles that are nucleated by hnRNP C. Despite their abundance, however, it remained unclear whether these particles control pre-mRNA processing. Here, we developed individual-nucleotide resolution UV cross-linking and immunoprecipitation (iCLIP) to study the role of hnRNP C in splicing regulation. iCLIP data show that hnRNP C recognizes uridine tracts with a defined long-range spacing consistent with hnRNP particle organization. hnRNP particles assemble on both introns and exons but remain generally excluded from splice sites. Integration of transcriptome-wide iCLIP data and alternative splicing profiles into an 'RNA map' indicates how the positioning of hnRNP particles determines their effect on the inclusion of alternative exons. The ability of high-resolution iCLIP data to provide insights into the mechanism of this regulation holds promise for studies of other higher-order ribonucleoprotein complexes