Recovering Heading for Visually-Guided Navigation

We present a model for recovering the direction of heading of an observer who is moving relative to a scene that may contain self-moving objects. The model builds upon an algorithm proposed by Rieger and Lawton (1985), which is based on earlier work by Longuet-Higgens and Prazdny (1981). The algorithm uses velocity differences computed in regions of high depth variation to estimate the location of the focus of expansion, which indicates the observer's heading direction. We relate the behavior of the proposed model to psychophysical observations regarding the ability of human observers to judge their heading direction, and show how the model can cope with self-moving objects in the environment. We also discuss this model in the broader context of a navigational system that performs tasks requiring rapid sensing and response through the interaction of simple task-specific routines

Tracking Vector Magnetograms with the Magnetic Induction Equation

The differential affine velocity estimator (DAVE) developed in Schuck (2006) for estimating velocities from line-of-sight magnetograms is modified to directly incorporate horizontal magnetic fields to produce a differential affine velocity estimator for vector magnetograms (DAVE4VM). The DAVE4VM's performance is demonstrated on the synthetic data from the anelastic pseudospectral ANMHD simulations that were used in the recent comparison of velocity inversion techniques by Welsch (2007). The DAVE4VM predicts roughly 95% of the helicity rate and 75% of the power transmitted through the simulation slice. Inter-comparison between DAVE4VM and DAVE and further analysis of the DAVE method demonstrates that line-of-sight tracking methods capture the shearing motion of magnetic footpoints but are insensitive to flux emergence -- the velocities determined from line-of-sight methods are more consistent with horizontal plasma velocities than with flux transport velocities. These results suggest that previous studies that rely on velocities determined from line-of-sight methods such as the DAVE or local correlation tracking may substantially misrepresent the total helicity rates and power through the photosphere.Comment: 30 pages, 13 figure

Fanchette : Tambourine Dance

https://digitalcommons.library.umaine.edu/mmb-ps/2073/thumbnail.jp

Accomplishments of the NASA Johnson Space Center portion of the soil moisture project in fiscal year 1981

The NASA/JSC ground scatterometer system was used in a row structure and row direction effects experiment to understand these effects on radar remote sensing of soil moisture. Also, a modification of the scatterometer system was begun and is continuing, to allow cross-polarization experiments to be conducted in fiscal years 1982 and 1983. Preprocessing of the 1978 agricultural soil moisture experiment (ASME) data was completed. Preparations for analysis of the ASME data is fiscal year 1982 were completed. A radar image simulation procedure developed by the University of Kansas is being improved. Profile soil moisture model outputs were compared quantitatively for the same soil and climate conditions. A new model was developed and tested to predict the soil moisture characteristic (water tension versus volumetric soil moisture content) from particle-size distribution and bulk density data. Relationships between surface-zone soil moisture, surface flux, and subsurface moisture conditions are being studied as well as the ways in which measured soil moisture (as obtained from remote sensing) can be used for agricultural applications

Deer-Activated Bio-Acoustic Frightening Device Deters White-Tailed Deer

White-tailed deer (Odocoileus virginianus) damage urban and suburban plantings as well as crops and stored feed. Public demand for non-lethal control methods is high. Several frightening devices are available for deer, but problems exist with most, including: ease of application, cost, acclimation by animals, and public acceptance. Frightening devices that have the greatest likelihood of being effective incorporate mechanisms triggered by animal activation or bioacoustic alarm or distress calls. We tested the efficacy of a frightening device that played pre-recorded distress calls of adult female white-tailed deer when activated by an infrared motion sensor. Potential benefits of the device are that deer are less likely to acclimate to animal-activated and infrequently projected calls and that distress calls may elicit a stronger and longer lasting response. We tested the product in DeSoto National Wildlife Refuge (DNWR) in eastern Nebraska and western Iowa during late winter 2010. We established 3 treatment sites and 3 control sites, each being 0.004 ha and located \u3e0.6 km apart to reduce the likelihood of dependence among treatments and associated controls. At each treatment site, we deployed deeractivated bioacoustics devices and motion-activated cameras to record deer responses to the devices. We maintained 1 13-day pretreatment period (10 Mar– 22 Mar) and 1 13-day treatment period (23 Mar– 4 Apr) and recorded breaches and consumption of feed by deer. The deer-activated bio-acoustic frightening device reduced deer entry into protected sites by 99.3% (δ = -558.00, P = 0.089) and bait consumption by 100% (δ = -75.20, P = 0.064). Unfortunately, small sample size (n = 3) and a natural decline in motivation of deer to access bait due to spring green-up diminished the statistical significance of results. The deer-activated bioacoustics device was effective, deer did not acclimate to the device, and the device was not invasive. The frightening device we evaluated demonstrated potential for reducing damage in disturbed environments and agricultural settings. The device currently is being marked as DeerShield by BirdGuard (http://www.deershieldpro.com/). We thank Greg Clements, Scott Groepper, Greg Phillips, and Dave Baasch for assistance. We thank Tom Cox, Mindy Sheets, and the staff at DNWR for access and assistance. Funding was provided by the United States Department of Agriculture, Animal and Plant Health Inspection Service, Wildlife Services, National Wildlife Research Center and the University of Nebraska-Lincoln School of Natural Resources

Mouse cytomegalovirus-experienced ILC1s acquire a memory response dependent on the viral glycoprotein m12.

Innate lymphoid cells (ILCs) are tissue-resident sentinels that are essential for early host protection from pathogens at initial sites of infection. However, whether pathogen-derived antigens directly modulate the responses of tissue-resident ILCs has remained unclear. In the present study, it was found that liver-resident type 1 ILCs (ILC1s) expanded locally and persisted after the resolution of infection with mouse cytomegalovirus (MCMV). ILC1s acquired stable transcriptional, epigenetic and phenotypic changes a month after the resolution of MCMV infection, and showed an enhanced protective effector response to secondary challenge with MCMV consistent with a memory lymphocyte response. Memory ILC1 responses were dependent on the MCMV-encoded glycoprotein m12, and were independent of bystander activation by proinflammatory cytokines after heterologous infection. Thus, liver ILC1s acquire adaptive features in an MCMV-specific manner

Surface Topographical and Compositional Characterization Using Backscattered Electron Methods

Two pairs of diametrically opposed Schottky surface barrier diodes in a modified scanning electron microscope (SEM) are used to reconstruct surface elevations and composition differences. An empirically determined function of difference of signals from opposing diodes is used to calculate slopes, which are then integrated to elevations by an efficient 2-dimensional Fast Fourier Transform. Composition differences are distinguished by variations in the overall backscattered electron (BSE) intensity estimated by the sum of the four diode signals. Arithmetic average roughness measurements from the BSE device are within 10% of stylus surface tracer measurements when surface slopes average less than 6 degrees and maximum slopes are less than 45°; shadowing effects for rough surfaces, aliasing, and averaging effects from Fourier integration are apparent. Composition measurements show distinction of high contrast phases; phase boundary-slope interactions are noted

High Resolution Hybrid Pixel Sensors for the e+e- TESLA Linear Collider Vertex Tracker

In order to fully exploit the physics potential of a future high energy e+e- linear collider, a Vertex Tracker, providing high resolution track reconstruction, is required. Hybrid Silicon pixel sensors are an attractive option, for the sensor technology, due to their read-out speed and radiation hardness, favoured in the high rate environment of the TESLA e+e- linear collider design but have been so far limited by the achievable single point space resolution. In this paper, a conceptual design of the TESLA Vertex Tracker, based on a novel layout of hybrid pixel sensors with interleaved cells to improve their spatial resolution, is presented.Comment: 12 pages, 5 figures, to appear in the Proceedings of the Vertex99 Workshop, Texel (The Netherlands), June 199