TriG - A GNSS Precise Orbit and Radio Occultation Space Receiver

The GPS radio occultation (RO) technique [1] produces measurements in the ionosphere and neutral atmosphere [2] that contribute to monitoring space weather and climate change; and improving operational weather prediction. The high accuracy of RO soundings, traceable to SI standards, makes them ideal climate benchmark observations. For weather applications, RO observations improve the accuracy of weather forecasts by providing temperature and moisture profiles of sub-km vertical resolution, over land and ocean and in the presence of clouds. JPL is currently flying a handful of RO instruments [3] on various satellites in Low Earth Orbit (LEO). Although these receivers have served to pioneer occultation measurements, various advances in technology and understanding of the RO technique along with availability of new signals from GPS and other GNSS satellites allow us to design an improved next generation space-based Precise Orbit Determination (POD) and RO receiver, the TriG receiver. The paper describes the architecture and implementation of the JPL TriG receiver as well as results obtained with a prototype receiver demonstrating key technologies necessary for a next-generation space science receiver

Bis(tetraphenylphosphonium) di-μ-iodido-bis[diiodidopalladate(II)].

The title compound, (PPh4)2[Pd2I6], was obtained unintentionally as the product of an attempted synthesis of a tripalladium sandwich complex. The molecular dimensions are unexceptional and the Pd---Pd distance, at 3.8183 (12) A,is much too long for any Pd—Pd interaction. Pd has a typical square-planar coordination geometry and the centrosymmetric anion is essentially planar

DNaseI hypersensitive sites 1, 2 and 3 of the human β-globin dominant control region directs position-independent expression.

The human beta-globin dominant control region (DCR) which flanks the multigene beta-globin locus directs high level, site of integration independent, copy number dependent expression on a linked human beta-globin gene in transgenic mice and stably transfected mouse erythroleukemia (MEL) cells. We have assayed each of the individual DNaseI hypersensitive regions present in the full 15kb DCR for position independence and copy number dependence of a linked beta-globin gene in transgenic mice. The results show that at least three of the individual DNaseI hypersensitive site regions (sites 1, 2 and 3), though expressing at lower levels than the full DCR, are capable of position independent, copy number dependent expression. Site 2 alone directs the highest level of expression of the single site constructs, producing nearly 70% of the level of the full DCR. Sites 1 and 3 each provide 30% of the full activity. Deletion of either site 2 or 3 from the complete set significantly reduces the level of expression, but does not effect position independence or copy number dependence. This demonstrates that sites 2 and 3 are required for full expression and suggests that all the sites are required for the full expression of even a single gene from this multigene locus