A cost-effective adverse-weather precision guidance system

This SAND report documents the results of an LDRD project undertaken to study the accuracy of terrain-aided navigation coupled with highly accurate topographic maps. A revolutionary new mapping technology, interferometric synthetic aperture radar (IFSAR), has the ability to make terrain maps of extremely high accuracy and spatial resolution, more than an order of magnitude better than currently available DMA map products. Using a laser altimeter and the Sandia Labs Twin Otter Radar Testbed, fix accuracies of less than 3 meters CEP were obtained over urban and natural terrain regions

Fusion of radar data to extract 3-dimensional objects LDRD final report

Interferometric Synthetic Aperture Radar (IFSAR) is a very promising technology for remote mapping of 3-Dimensional objects. In particular, 3-D maps of urban areas are extremely important to a wide variety of users, both civilian and military. However, 3-D maps produced by traditional optical stereo (stereogrammetry) techniques can be quite expensive to obtain, and accurate urban maps can only be obtained with a large amount of human-intensive interpretation work. IFSAR has evolved over the last decade as a mapping technology that promises to eliminate much of the human-intensive work in producing elevation maps. However, IFSAR systems have only been robustly demonstrated in non-urban areas, and have not traditionally been able to produce data with enough detail to be of general use in urban areas. Sandia Laboratories Twin Otter IFSAR was the first mapping radar system with the proper parameter set to provide sufficiently detailed information in a large number of urban areas. The goal of this LDRD was to fuse previously unused information derived from IFSAR data in urban areas that can be used to extract accurate digital elevation models (DEMs) over wide areas without intensive human interaction

A high-resolution, four-band SAR testbed with real-time image formation

This paper describes the Twin-Otter SAR Testbed developed at Sandia National Laboratories. This SAR is a flexible, adaptable testbed capable of operation on four frequency bands: Ka, Ku, X, and VHF/UHF bands. The SAR features real-time image formation at fine resolution in spotlight and stripmap modes. High-quality images are formed in real time using the overlapped subaperture (OSA) image-formation and phase gradient autofocus (PGA) algorithms

Taming the tiger by the tail: modulation of DNA damage responses by telomeres

Telomeres are by definition stable and inert chromosome ends, whereas internal chromosome breaks are potent stimulators of the DNA damage response (DDR). Telomeres do not, as might be expected, exclude DDR proteins from chromosome ends but instead engage with many DDR proteins. However, the most powerful DDRs, those that might induce chromosome fusion or cell-cycle arrest, are inhibited at telomeres. In budding yeast, many DDR proteins that accumulate most rapidly at double strand breaks (DSBs), have important functions in physiological telomere maintenance, whereas DDR proteins that arrive later tend to have less important functions. Considerable diversity in telomere structure has evolved in different organisms and, perhaps reflecting this diversity, different DDR proteins seem to have distinct roles in telomere physiology in different organisms. Drawing principally on studies in simple model organisms such as budding yeast, in which many fundamental aspects of the DDR and telomere biology have been established; current views on how telomeres harness aspects of DDR pathways to maintain telomere stability and permit cell-cycle division are discussed

Gain-of-function glutamate receptor interacting protein 1 variants alter GluA2 recycling and surface distribution in patients with autism

Glutamate receptor interacting protein 1 (GRIP1) is a neuronal scaffolding protein that interacts directly with the C termini of glutamate receptors 2/3 (GluA2/3) via its PDZ domains 4 to 6 (PDZ4-6). We found an association (P < 0.05) of a SNP within the PDZ4-6 genomic region with autism by genotyping autistic patients (n = 480) and matched controls (n = 480). Parallel sequencing identified five rare missense variants within or near PDZ4-6 only in the autism cohort, resulting in a higher cumulative mutation load (P = 0.032). Two variants correlated with a more severe deficit in reciprocal social interaction in affected sibling pairs from proband families. These variants were associated with altered interactions with GluA2/3 and faster recycling and increased surface distribution of GluA2 in neurons, suggesting gain-of-function because GRIP1/2 deficiency showed opposite phenotypes. Grip1/2 knockout mice exhibited increased sociability and impaired prepulse inhibition. These results support a role for GRIP in social behavior and implicate GRIP1 variants in modulating autistic phenotype