71 research outputs found
Magnetism in SQUIDs at Millikelvin Temperatures
We have characterized the temperature dependence of the flux threading dc
SQUIDs cooled to millikelvin temperatures. The flux increases as 1/T as
temperature is lowered; moreover, the flux change is proportional to the
density of trapped vortices. The data is compatible with the thermal
polarization of surface spins in the trapped fields of the vortices. In the
absence of trapped flux, we observe evidence of spin-glass freezing at low
temperature. These results suggest an explanation for the "universal" 1/f flux
noise in SQUIDs and superconducting qubits.Comment: 4 pages, 4 figure
Underwater inspection using sonar-based volumetric submaps
We propose a submap-based technique for mapping of underwater structures with complex geometries. Our approach relies on the use of probabilistic volumetric techniques to create submaps from multibeam sonar scans, as these offer increased outlier robustness. Special attention is paid to the problem of denoising/enhancing sonar data. Pairwise submap alignment constraints are used in a factor graph framework to correct for navigation drift and improve map accuracy. We provide experimental results obtained from the inspection of the running gear and bulbous bow of a 600-foot, Wright-class supply ship.United States. Office of Naval Research (N00014-12-1-0093)United States. Office of Naval Research (N00014-14-1-0373
Education and Manpower in the Omaha SMSA
This report is a compilation of statistics having to do with education and manpower in the Omaha Standard Metropolitan Statistical Area (SMSA). The SMSA consists of Douglas and Sarpy Counties in Nebraska and Pottawattamie County in Iowa
Towards Autonomous Ship Hull Inspection using the Bluefin HAUV
URL is to paper listed on conference scheduleIn this paper we describe our effort to automate ship hull inspection for security
applications. Our main contribution is a system that is capable of drift-free
self-localization on a ship hull for extended periods of time. Maintaining accurate
localization for the duration of a mission is important for navigation and for
ensuring full coverage of the area to be inspected. We exclusively use onboard
sensors including an imaging sonar to correct for drift in the vehicle’s navigation
sensors. We present preliminary results from online experiments on a ship hull. We
further describe ongoing work including adding capabilities for change detection
by aligning vehicle trajectories of different missions based on a technique recently
developed in our lab.United States. Office of Naval Research (grant N00014-06- 10043
Cross-tissue analysis of allelic X-chromosome inactivation ratios resolves features of human development
X-chromosome inactivation (XCI) is a random, permanent, and developmentally early
epigenetic event that occurs during mammalian embryogenesis. We harness these features of
XCI to investigate characteristics of early lineage specification events during human
development. We initially assess the consistency of X-inactivation and establish a robust set of
XCI-escape genes. By analyzing variance in XCI ratios across tissues and individuals, we find
that XCI is completed prior to tissue specification and at a time when 6-16 cells are fated for all
tissue lineages. Additionally, we exploit tissue specific variability to characterize the number of
cells present at the time of each tissue’s lineage commitment, ranging from approximately 20
cells in liver and whole blood tissues to 80 cells in brain tissues. By investigating variance of
XCI ratios using adult tissue, we resolve key features of human development otherwise difficult
to ascertain experimentally and develop scalable methods easily applicable to future data
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