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140 results on '"Rideout, W."'

5. Gaussian Markov random field priors in ionospheric 3-D multi-instrument tomography

Author

Norberg, J. (Johannes), Vierinen, J. (Juha), Roininen, L. (Lassi), Orispää, M. (Mikko), Kauristie, K. (Kirsti), Rideout, W. C. (William C.), Coster, A. J. (Anthea J.), Lehtinen, M. S. (Markku S.), Norberg, J. (Johannes), Vierinen, J. (Juha), Roininen, L. (Lassi), Orispää, M. (Mikko), Kauristie, K. (Kirsti), Rideout, W. C. (William C.), Coster, A. J. (Anthea J.), and Lehtinen, M. S. (Markku S.)

Abstract

In ionospheric tomography, the atmospheric electron density is reconstructed from different electron density related measurements, most often from ground-based measurements of satellite signals. Typically, ionospheric tomography suffers from two major complications. First, the information provided by measurements is insufficient and additional information is required to obtain a unique solution. Second, with necessary spatial and temporal resolutions, the problem becomes very high dimensional, and hence, computationally infeasible. With Bayesian framework, the required additional information can be given with prior probability distributions. The approach then provides physically quantifiable probabilistic interpretation for all model variables. Here, Gaussian Markov random fields (GMRFs) are used for constructing the prior electron density distribution. The use of GMRF introduces sparsity to the linear system, making the problem computationally feasible. The method is demonstrated over Fennoscandia with measurements from global navigation satellite system (GNSS) and low Earth orbit (LEO) satellite receiver networks, GNSS occultation receivers, LEO satellite Langmuir probes, and ionosonde and incoherent scatter radar measurements.

Published
2018

9. On the Relationship of SAPS to Storm-Enhanced Density

Author

AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE, Foster, J. C., Rideout, W., Sandel, B., Forrester, W. T., Rich, F. J., AIR FORCE RESEARCH LAB HANSCOM AFB MA SPACE VEHICLES DIRECTORATE, Foster, J. C., Rideout, W., Sandel, B., Forrester, W. T., and Rich, F. J.

Abstract

We use magnetic field-aligned mapping between the ionosphere and the magnetosphere to intercompare ground-based observations of storm enhanced density (SED), and plasmasphere drainage plumes imaged from space by the IMAGE EUV imager, with the enhanced inner-magnetosphere/ionosphere SAPS electric field which develops during large storms. We find that the inner edge of the SAPS electric field overlaps the erosion plume and that plume material is carried sunward in the SAPS overlap region. The two phenomena, SED in the ionosphere and the erosion plume at magnetospheric heights, define a common trajectory for upward- propagating cold plasma fluxes in the midnight-desk-post noon sector. The SAPS channel at ionospheric heights and its projection into the equatorial plane serve to define the sharp outer boundary of the erosion plume. The SAPS electric field abuts and overlaps both the plasmasphere boundary layer and the plasmasphere erosion plume from pre-midnight through post-noon local times., The original document contains color images. Published in the Journal of Atmospheric and Solar-Terrestrial Physics v69, p303-313, 2007. Sponsored in part by NASA Award No., NAG5-12875, National Science Foundation (NSF) under Agreement No., ATM-0233230.

Published
2007

12. LETTERS.

Author

HURDLE, G. S., SIMONS, HENRY C., NICHOLAS, M. B., HENDRICKSON, A. M., RIDEOUT, W. L., HALE GRAY, DANIEL, RYDER, STEPHEN, MARTIN, A. C., FULLER, A. VERNE, VAN DERVEER, L. C., and NACHOD, FREDERICK C.

Subjects
MILITARY personnel
Published
1944

13. Letters.

Author

CORBETT, EDWARD P. J., HARRINGTON, JOHN, SUTTIE, RICHARD B., FREEDMAN, B., ADAIR, PHILIP, POPE, WILLARD B., SOUTHARD, MARGARET LEE, GIESELER, CARL A., ERICKSON, RODNEY, RIDEOUT, W. L., OLSON, RUTH, and FARRER, CHARLES M.

Subjects
COMMUNISM, POPES, SPELLING errors, TWENTIETH century, HISTORY of communism
Published
1947

17. Statistical framework for estimating GNSS bias.

Author

Vierinen, J., Coster, A. J., Rideout, W. C., Erickson, P. J., and Norberg, J.

Subjects
GLOBAL Positioning System, ELECTRON distribution, IONOSPHERIC electric fields
Abstract

We present a statistical framework for estimating global navigation satellite system (GNSS) non-ionospheric differential time delay bias. The biases are estimated by examining differences of measured line integrated electron densities (TEC) that are scaled 5 to equivalent vertical integrated densities. The spatio-temporal variability, instrumentation dependent errors, and errors due to inaccurate ionospheric altitude profile assumptions are modeled as structure functions. These structure functions determine how the TEC differences are weighted in the linear least-squares minimization procedure, which is used to produce the bias estimates. A method for automatic detection and removal of outlier measurements that do not fit into a model of receiver bias is also described. The same statistical framework can be used for a single receiver station, but it also scales to a large global network of receivers. In addition to the Global Positioning System (GPO), the method is also applicable to other dual frequency GNSS systems, such as GLONASS (Globalnaya Navigazionnaya Sputnikovaya Sistema). The use of the framework is demonstrated in practice through several examples. A specific implementation of the methods presented here are used to compute GPO receiver biases for measurements in the MIT Haystack Madrigal distributed database system. Results of the new algorithm are compared with the current MIT Haystack Observatory MAPGPS bias determination algorithm. The new method is found to produce estimates of receiver bias that have reduced day-to-day variability and more consistent coincident vertical TEC values. [ABSTRACT FROM AUTHOR]

Published
2015
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18. Working With the Courts in Child Protection

Author

Jones, William G., primary, Bragg, H. Lien, additional, Davidson, Howard, additional, Hardin, Mark, additional, Heydon, Beverly, additional, Pinto, Katherine, additional, Rideout, W. Stephen, additional, and Webster, Sarah, additional

Published
2006
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20. Multiradar observations of the polar tongue of ionization

Author

Foster, J. C., primary, Coster, A. J., additional, Erickson, P. J., additional, Holt, J. M., additional, Lind, F. D., additional, Rideout, W., additional, McCready, M., additional, van Eyken, A., additional, Barnes, R. J., additional, Greenwald, R. A., additional, and Rich, F. J., additional

Published
2005
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47. A Fish Jam on Kelsey Creek

Author

Rideout, W. L., Rideout, W. L., Rideout, W. L., and Rideout, W. L.

Abstract

Overland monthly and Out West magazine. / Volume 34, Issue 202, Page(s) 333, (dlps) volume: ahj1472.2-34.202, (dlps) article: ahj1472.2-34.202:12, http://quod.lib.umich.edu/t/text/accesspolicy.html

50. Developmental potential of mouse primordial germ cells.

Author

Kato, Y, Rideout, W M, Hilton, K, Barton, S C, Tsunoda, Y, and Surani, M A

Abstract

There are distinctive and characteristic genomic modifications in primordial germ cells that distinguish the germ cell lineage from somatic cells. These modifications include, genome-wide demethylation, erasure of allele-specific methylation associated with imprinted genes, and the re-activation of the X chromosome. The allele-specific differential methylation is involved in regulating the monoallelic expression, and thus the gene dosage, of imprinted genes, which underlies functional differences between parental genomes. However, when the imprints are erased in the germ line, the parental genomes acquire an equivalent epigenetic and functional state. Therefore, one of the reasons why primordial germ cells are unique is because this is the only time in mammals when the distinction between parental genomes ceases to exist. To test how the potentially imprint-free primordial germ cell nuclei affect embryonic development, we transplanted them into enucleated oocytes. Here we show that the reconstituted oocyte developed to day 9.5 of gestation, consistently as a small embryo and a characteristic abnormal placenta. The embryo proper also did not progress much further even when the inner cell mass was 'rescued' from the abnormal placenta by transfer into a tetraploid host blastocyst. We found that development of the experimental conceptus was affected, at least in part, by a lack of gametic imprints, as judged by DNA methylation and expression analysis of several imprinted genes. The evidence suggests that gametic imprints are essential for normal development, and that they can neither be initiated nor erased in mature oocytes; these properties are unique to the developing germ line.

Published
1999

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