Current and planned use of the Navstar Global Positioning System by NASA

NASA was quick to realize the potential that the Global Positioning System (GPS) had to offer for its many diverse vehicles, experiments and platforms. Soon after the first Block 1 GPS satellites were launched, NASA began to use the tremendous capabilities that they had to offer. Even with a partial GPS constellation in place, important results have been obtained about the shape, orientation and rotation of the earth and calibration of the ionosphere and troposphere. These calibrations enhance geophysical science and facilitate the navigation of interplanetary spacecraft. Some very important results have been obtained in the continuing NASA program for aircraft terminal area operations. Currently, a large amount of activity is being concentrated on real time kinematic carrier phase tracking which has the potential to revolutionize aircraft navigation. This year marks the launch of the first GPS receiver equipped earth-orbiting NASA spacecraft: the Extreme Ultraviolet Explorer and the Ocean Topography Experiment (TOPEX/Poseidon). This paper describes a cross section of GPS-based research at NASA

Political participation of unemployed youth: the moderator effect of associational membership

<span class="abs_content">This article discusses how associational membership can compensate for that lack of opportunities and motivation necessary for political participation that unemployment usually provokes. We investigate such a moderator effect of associational membership by means of a CATI survey of young people realized in two different cities: Turin in Italy and Kielce in Poland. The survey was part of a larger research on youth unemployment funded by the EU FP7 program (Younex). We propose an exploratory analysis allowing us to assess at a low level of abstraction and through a local level comparison, how far associational membership performs even across different contexts as a promoter of political engagement of a specific group of young, deprived, individuals.</span><br /

Connexin 40 promoter-based enrichment of embryonic stem cell-derived cardiovascular progenitor cells

Background: Pluripotent embryonic stem (ES) cells that can differentiate into functional cardiomyocytes as well as vascular cells in cell culture may open the door to cardiovascular cell transplantation. However, the percentage of ES cells in embryoid bodies (EBs) which spontaneously undergo cardiovascular differentiation is low (< 10%), making strategies for their specific labeling and purification indispensable. Methods: The human connexin 40 (Cx40) promoter was isolated and cloned in the vector pEGFP. The specificity of the construct was initially assessed in Xenopus embryos injected with Cx40-EGFP plasmid DNA. Stable Cx40-EGFP ES cell clones were differentiated and fluorescent cells were enriched manually as well as via fluorescence-activated cell sorting. Characterization of these cells was performed with respect to spontaneous beating as well as via RT-PCRs and immunofluorescent stainings. Results: Cx40-EGFP reporter plasmid injection led to EGFP fluorescence specifically in the abdominal aorta of frog tadpoles. After crude manual enrichment of highly Cx40-EGFP- positive EBs, the appearance of cardiac and vascular structures was increased approximately 3-fold. Immuno fluorescent stainings showed EGFP expression exclusively in vascular-like structures simultaneously expressing von Willebrand factor and in formerly beating areas expressing alpha-actinin. Cx40-EGFP-expressing EBs revealed significantly higher numbers of beating cardiomyocytes and vascular-like structures. Semiquantitative RT-PCRs confirmed an enhanced cardiovascular differentiation as shown for the cardiac markers Nkx2.5 and MLC2v, as well as the endothelial marker vascular endothelial cadherin. Conclusions: Our work shows the feasibility of specific labeling and purification of cardiovascular progenitor cells from differentiating EBs based on the Cx40 promoter. We provide proof of principle that the deleted CD4 (Delta CD4) surface marker-based method for magnetic cell sorting developed by our group will be ideally suitable for transference to this promoter. Copyright (c) 2008 S. Karger AG, Basel

Study of the application of perceptrons for prediction of solar flares. solar flare forecasting with a recognizing automaton final report, phase ii

Perceptrons for solar flare prediction with pattern recognition automato

Gas levitator having fixed levitation node for containerless processing

A method and apparatus is disclosed for levitating a specimen of material in a containerless environment at a stable nodal position independent of gravity. An elongated levitation tube has a contoured interior in the form of convergent section, constriction, and a divergent section in which the levitation node is created. A gas flow control means prevents separation of flow from the interior walls in the region of a specimen. The apparatus provides for levitating and heating the specimen simultaneously by combustion of a suitable gas mixture combined with an inert gas

The Impact of Meteorology on Ozone Levels in the Lake Tahoe Basin

The Lake Tahoe Basin is located on the California-Nevada border and occasionally experiences elevated levels of ozone exceeding the 70 ppb California Air Resources Board (CARB) ambient air quality standard (8-hour average). Previous studies indicate that both the local generation of ozone in the Basin and long-range transport from out-of-Basin sources are important in contributing to ozone exceedances, but little is known about the impact of meteorology on the distribution of ozone source regions. In order to develop a better understanding of the factors affecting ozone levels and sources in the Lake Tahoe Basin, this study combines observational data from a 2010 and 2012 summer field campaigns, HYSPLIT back trajectories, and WRF model output to examine the meteorological influences of ozone transport in the topographically complex Lake Tahoe Basin. Findings from the field work portions of this study include enhanced background ozone levels at higher elevations, the local circulation pattern of lake breezes occurring at Lake level sites, and an indication that ozone precursors are coming off the Lake. Our analysis also showed that if transport of ozone does occur, it is more likely to come from the San Joaquin Valley to the south rather than originate in the large cities to the west, such as Sacramento and San Francisco. Analysis of modeled PBL schemes as compared with observational data showed that the ACM2 PBL scheme best represented the geographical domain. The ACM2 PBL scheme was then used to show wind circulation patterns in the Lake Tahoe Basin and concluded that there is decent vertical mixing over the Basin and no indication of ozone transport from the west however some indication of transport from the east. Overall this study concludes that transport from the west is less significant than transport from the south and east, and that transport only influences ozone values at higher elevations. Within the Basin itself (at lower elevations), local factors including mixing depth, rising or sinking air, and lake/land breeze circulations are more significant in influencing ozone values

Density-matrix spectra for integrable models

The spectra which occur in numerical density-matrix renormalization group (DMRG) calculations for quantum chains can be obtained analytically for integrable models via corner transfer matrices. This is shown in detail for the transverse Ising chain and the uniaxial XXZ Heisenberg model and explains in particular their exponential character in these cases.Comment: 14 pages, 7 figures, to appear in Ann. Physi

Dwarf galaxies with AGN and their environments in observations and simulations

This thesis is a study of dwarf galaxies with active galactic nucleis (AGN) characteristics, their environments, and identification of them in both observations and simulations. More specifically, it attempts to answer the questions of what environmental conditions are favourable for AGN activity, if environmental has any influence at all, and to what degree current AGN identification tools are suitable for dwarf galaxies. Using the observational catalogue NASASloan Atlas and the Baldwin-Philips-Terlevich (BPT) and WHAN diagrams as diagnostics, no connection between AGN activity and environment is found based on 62 258 dwarf galaxies, although a weak connection cannot be refuted in a redshift-limited sample of BPT galaxies, while the IllustrisTNG simulation shows an increase in AGN occupation fraction of its 6 771 dwarf galaxies if they have recent mergers. Additionally, dense environments are found to be detrimental for AGN activity, but this finding may be due to numerical reasons. Machinelearning does not rank environmental features highly for identifying AGN, but predicted AGN galaxies reside closer to a massive galaxy and denser neighbourhoods. Preliminary results indicate that the best model relies internal features. Other studies find multi-wavelength data provide the best venue to obtain a complete set of AGN in dwarf galaxies, and simulations are now utilising higher resolution and improved black hole (BH) modelling, enabling accurate evolutionary paths of dwarf galaxies. The seemingly contradictory results between different approaches can in part be explained selection bias (e.g BPT favours unobscured AGN), numerical effects (e.g overmassive BH seeding), and statistical framework used toquantify differences. Future work involves constructing a more complete and accurate sample of dwarf AGN, achieved through using multi-wavelength data, higher sensitivity observations like integrated field unit spectroscopy, and simulations with improved dwarf galaxy and BHmodelling, tying together the many strings by a fine tuned machine learning approach

Sequelae of childhood sexual abuse and chronic headache pain in women

For many years the association of headache with CSA has been postulated and results have been similar across studies indicating a robust connection. Chronic headache is one of the most common causes of visits to physicians and contributes to decreased quality of life for those who suffer with them. Although CSA is detrimental to both men and women, evidence supports that women are more likely to suffer from chronic somatic headache pain than men. Therefore, it is hypothesized that chronic headache is significantly more common among women with a history of childhood sexual abuse when compared to women who have not suffered CSA