Commercial applications of the ACTS mobile terminal millimeter-wave antennas

NASA's Jet Propulsion Laboratory is currently developing the Advanced Communications Technology Satellite (ACTS) Mobile Terminal (AMT), which will provide voice, data, and video communications to and from a vehicle (van, truck, or car) via NASA's geostationary ACTS satellite using the K- and K(sub a)-band frequency bands. The AMT is already planned to demonstrate a variety of communications from within the mobile vehicular environment, and within this paper a summary of foreseen commercial application opportunities is given. A critical component of the AMT is its antenna system, which must establish and maintain the basic RF link with the satellite. Two versions of the antenna are under development, each incorporating different technologies and offering different commercial applications

A satellite-tracking millimeter-wave reflector antenna system for mobile satellite-tracking

A miniature dual-band two-way mobile satellite tracking antenna system mounted on a movable ground vehicle includes a miniature parabolic reflector dish having an elliptical aperture with major and minor elliptical axes aligned horizontally and vertically, respectively, to maximize azimuthal directionality and minimize elevational directionality to an extent corresponding to expected pitch excursions of the movable ground vehicle. A feed-horn has a back end and an open front end facing the reflector dish and has vertical side walls opening out from the back end to the front end at a lesser horn angle and horizontal top and bottom walls opening out from the back end to the front end at a greater horn angle. An RF circuit couples two different signal bands between the feed-horn and the user. An antenna attitude controller maintains an antenna azimuth direction relative to the satellite by rotating it in azimuth in response to sensed yaw motions of the movable ground vehicle so as to compensate for the yaw motions to within a pointing error angle. The controller sinusoidally dithers the antenna through a small azimuth dither angle greater than the pointing error angle while sensing a signal from the satellite received at the reflector dish, and deduces the pointing angle error from dither-induced fluctuations in the received signal

Hydrographic Survey of Chaktomuk, the Confluence of the Mekong, Tonlé Sap, and Bassac Rivers Near Phnom Penh, Cambodia, 2012

The U.S. Geological Survey, in cooperation with the U.S. Department of State, Mekong River Commission, Phnom Penh Autonomous Port, and the Cambodian Ministry of Water Resources and Meteorology, completed a hydrographic survey of Chaktomuk, which is the confluence of the Mekong, Tonlé Sap (also spelled Tônlé Sab), and Bassac Rivers near Phnom Penh, Cambodia. The hydrographic survey used a high-resolution multibeam echosounder mapping system to map the riverbed during April 21–May 2, 2012. The multibeam echosounder mapping system was made up of several components: A RESON Seabat™ 7125 multibeam echosounder, an inertial measurement unit and navigation unit, data collection computers, and a Real-Time Kinematic (RTK) Global Navigation Satellite System (GNSS) base station. The survey area was divided into six survey subreaches and each subreach was surveyed within 3 days along survey lines oriented parallel to the flow direction. Complete coverage of the riverbed was the operational objective; however, to obtain broad spatial coverage, gaps between parallel swaths were permitted, especially in wide, shallow areas where multibeam swath widths were narrow. The survey was referenced to two existing bench marks with known geographic coordinates by establishing a GNSS base station on the bench marks each day and using real-time corrections from the base station to correct boat navigation data. The World Geodetic System of 1984 (WGS 84) ellipsoid was used during data collection to reference height, and data were adjusted to the local datum, Ha Tien 1960, during postprocessing. The quality of hydrographic surveys was described by an uncertainty estimate called total propagated uncertainty (TPU). Calculations of TPU were completed for the hydrographic survey data resulting in the maximum TPU of 0.33 meters. The mean and median TPUs were 0.18 meters, and 99.9 percent of TPU values were less than 0.25 meters. Detailed hydrographic maps of Mekong, Tonlé Sap, and Bassac Rivers showing the riverbed elevations surveyed April 21–May 2, 2012, referenced to Ha Tien 1960 were produced. The surveyed area included a 2-km stretch of the Mekong River between the confluence with the Tonlé Sap and Bassac Rivers, and extended 4 km upstream and 3.6 km downstream from the 2,000-m confluence stretch of the Mekong River. In addition, 0.7 km of the Bassac River downstream and 3.5 km of the Tonlé Sap River (from the confluence to Chroy Changvar Bridge) upstream from their confluence with the Mekong River were surveyed. Riverbed features (such as dunes, shoals, and the effects of sediment mining, which were observed during data collection) are visible on the hydrographic maps. All surveys were completed at low annual water levels as referenced to nearby Mekong River Commission streamflow-gaging stations. Riverbed elevations surveyed ranged from 24.08 m below to 1.54 m above Ha Tien 1960

Hypoxia Preconditioning Increases Survival and Decreases Expression of Toll-like Receptor 4 in Pulmonary Artery Endothelial Cells Exposed to Lipopolysaccharide

Pulmonary or systemic infections and hypoxemic respiratory failure are among the leading causes of admission to intensive care units, and these conditions frequently exist in sequence or in tandem. Inflammatory responses to infections are reproduced by lipopolysaccharide (LPS) engaging Toll-like receptor 4 (TLR4). Apoptosis is a hallmark of lung injury in sepsis. This study was conducted to determine whether preexposure to LPS or hypoxia modulated the survival of pulmonary artery endothelial cells (PAECs). We also investigated the role TLR4 receptor expression plays in apoptosis due to these conditions. Bovine PAECs were cultured in hypoxic or normoxic environments and treated with LPS. TLR4 antagonist TAK-242 was used to probe the role played by TLR4 receptors in cell survival. Cell apoptosis and survival were measured by caspase 3 activity and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) incorporation. TLR4 expression and tumor necrosis factor α (TNF-α) production were also determined. LPS increased caspase 3 activity in a TAK-242-sensitive manner and decreased MTT incorporation. Apoptosis was decreased in PAECs preconditioned with hypoxia prior to LPS exposure. LPS increased TNF-α production, and hypoxic preconditioning blunted it. Hypoxic preconditioning reduced LPS-induced TLR4 messenger RNA and TLR4 protein. TAK-242 decreased to baseline the LPS-stimulated expression of TLR4 messenger RNA regardless of environmental conditions. In contrast, LPS followed by hypoxia substantially increased apoptosis and cell death. In conclusion, protection from LPS-stimulated PAEC apoptosis by hypoxic preconditioning is attributable in part to reduction in TLR4 expression. If these signaling pathways apply to septic patients, they may account for differing sensitivities of individuals to acute lung injury depending on oxygen tensions in PAECs in vivo

Field Dependence of the Superconducting Basal Plane Anisotropy of TmNi2B2C

The superconductor TmNi2B2C possesses a significant four-fold basal plane anisotropy, leading to a square Vortex Lattice (VL) at intermediate fields. However, unlike other members of the borocarbide superconductors, the anisotropy in TmNi2B2C appears to decrease with increasing field, evident by a reentrance of the square VL phase. We have used Small Angle Neutron Scattering measurements of the VL to study the field dependence of the anisotropy. Our results provide a direct, quantitative measurement of the decreasing anisotropy. We attribute this reduction of the basal plane anisotropy to the strong Pauli paramagnetic effects observed in TmNi2B2C and the resulting expansion of vortex cores near Hc2.Comment: 8 pages, 6 figures, 1 tabl

Characterization of Lithium Stearate: Processing Aid for Filled Elastomers

This topical report presents work completed to characterize lithium stearate so a replacement supplier could be identified. Lithium stearate from Alfa Aesar and Chemtura was obtained and characterized along with the current material from Witco. Multiple methods were used to characterize the materials including Karl Fischer, FT-IR, differential scanning calorimetry, and thermogravimetric analysis

Rattus Model Utilizing Selective Pulmonary Ischemia Induces Bronchiolitis Obliterans Organizing Pneumonia

Bronchiolitis obliterans organizing pneumonia (BOOP), a morbid condition when associated with lung transplant and chronic lung disease, is believed to be a complication of ischemia. Our goal was to develop a simple and reliable model of lung ischemia in the Sprague-Dawley rat that would produce BOOP. Unilateral ischemia without airway occlusion was produced by an occlusive slipknot placed around the left main pulmonary artery. Studies were performed 7 days later. Relative pulmonary and systemic flow to each lung was measured by injection of technetium Tc 99m macroaggregated albumin. Histological sections were examined for structure and necrosis and scored for BOOP. Apoptosis was detected by immunohistochemistry with an antibody against cleaved caspase 3. Pulmonary artery blood flow to left lungs was less than 0.1% of the cardiac output, and bronchial artery circulation was ~2% of aortic artery flow. Histological sections from ischemic left lungs consistently showed Masson bodies, inflammation, and young fibroblasts filling the distal airways and alveoli, consistent with BOOP. In quantitative evaluation of BOOP using epithelial changes, inflammation and fibrosis were higher in ischemic left lungs than right or sham-operated left lungs. Apoptosis was increased in areas exhibiting histological BOOP, but there was no histological evidence of necrosis. Toll-like receptor 4 expression was increased in ischemic left lungs over right. An occlusive slipknot around the main left pulmonary artery in rats produces BOOP, providing direct evidence that ischemia without immunomodulation or coinfection is sufficient to initiate this injury. It also affords an excellent model to study signaling and genetic mechanisms underlying BOOP

Lung Injury Pathways: Adenosine Receptor 2B Signaling Limits Development of Ischemic Bronchiolitis Obliterans Organizing Pneumonia

Purpose/Aim of the Study: Adenosine signaling was studied in bronchiolitis obliterans organizing pneumonia (BOOP) resulting from unilateral lung ischemia. Materials and Methods: Ischemia was achieved by either left main pulmonary artery or complete hilar ligation. Sprague–Dawley (SD) rats, Dahl salt sensitive (SS) rats and SS mutant rat strains containing a mutation in the A2B adenosine receptor gene (Adora2b) were studied. Adenosine concentrations were measured in bronchoalveolar lavage (BAL) by HPLC. A2A (A2AAR) and A2B adenosine receptor (A2BAR) mRNA and protein were quantified. Results: Twenty-four hours after unilateral PA ligation, BAL adenosine concentrations from ischemic lungs were increased relative to contralateral lungs in SD rats. A2BAR mRNA and protein concentrations were increased after PA ligation while miR27a, a negatively regulating microRNA, was decreased in ischemic lungs. A2AAR mRNA and protein concentrations remained unchanged following ischemia. A2BAR protein was increased in PA ligated lungs of SS rats after 7 days, and 4 h after complete hilar ligation in SD rats. SS-Adora2b mutants showed a greater extent of BOOP relative to SS rats, and greater inflammatory changes. Conclusion: Increased A2BAR and adenosine following unilateral lung ischemia as well as more BOOP in A2BAR mutant rats implicate a protective role for A2BAR signaling in countering ischemic lung injury