Satellite Navigation for the Age of Autonomy

Global Navigation Satellite Systems (GNSS) brought navigation to the masses. Coupled with smartphones, the blue dot in the palm of our hands has forever changed the way we interact with the world. Looking forward, cyber-physical systems such as self-driving cars and aerial mobility are pushing the limits of what localization technologies including GNSS can provide. This autonomous revolution requires a solution that supports safety-critical operation, centimeter positioning, and cyber-security for millions of users. To meet these demands, we propose a navigation service from Low Earth Orbiting (LEO) satellites which deliver precision in-part through faster motion, higher power signals for added robustness to interference, constellation autonomous integrity monitoring for integrity, and encryption / authentication for resistance to spoofing attacks. This paradigm is enabled by the 'New Space' movement, where highly capable satellites and components are now built on assembly lines and launch costs have decreased by more than tenfold. Such a ubiquitous positioning service enables a consistent and secure standard where trustworthy information can be validated and shared, extending the electronic horizon from sensor line of sight to an entire city. This enables the situational awareness needed for true safe operation to support autonomy at scale.Comment: 11 pages, 8 figures, 2020 IEEE/ION Position, Location and Navigation Symposium (PLANS

Constraining the Temperature of Impact Melt from the Mistastin Lake Impact Structure Using Zircon Crystal Structures

Impact melt is a product of hyper-velocity impact events formed by the instantaneous melting of near-surface target rocks. Constraining the temperature of impact melt is vital to understanding its prograde heating and cooling history, which can have implications for inferring the environment of early Earth ~4.0 billion years ago when microbial life potentially arose. To date, only one datum on the initial impact melt temperature has been derived by Timms et al. These authors studied zirconia microstructures and crystallographic orientations that revealed the former presence of cubic zirconia, found in a black impact glass at the Mistastin Lake impact structure, Canada. The presence of cubic zirconia indicates a minimum temperature for the impact melt of >2370C from the dissociation temperature of zircon to cubic zirconia and liquid SiO2. With only one temperature datum, it is still difficult to constrain the entire temperature range experienced during the impact melting process; from its instantaneous formation to thermal equilibrium with the cold clasts collected along the crater floor and walls. In addition, obtaining a temperature value from only one type of impactite limits the inferred temperature range, because each impactite experiences a different cooling history. In this study, we present a preliminary investigation of 61 zircon crystals, 14 of which are similar to those studied by Timms et al., from the Mistastin Lake impact structure. To acquire a more accurate temperature profile representative of impact melt, zircon crystals were collected from different types of impactites containing impact melt, including additional samples of the black impact glass studied by Timms et al

Advances in understanding the interaction between the gut microbiota and adaptive mucosal immune responses

Commensal gut bacteria are necessary for the complete development of mucosal innate and adaptive immunity and thus may influence intestinal and systemic immune disorders. Recent work has advanced our understanding of this association by identification of a single taxon of the murine microbiota which can stimulate T-cell development and differentiation. It is hoped that further characterization of the mechanisms involved will enable targeted manipulation of the microbiota-immune system relationship

Effects of an Adolescent Asthma Education Intervention on Knowledge, Intention, Behavior, Self-Efficacy and Self-Consciousness

In this study, we evaluated the effects of an asthma education intervention, guided by social cognitive theory, on knowledge, intention, behavior, self-efficacy, and self-consciousness. The sample consisted of 87 asthmatic adolescents in six middle and/or high schools in California. A non-equivalent comparison group design, with delayed intervention in the comparison group, was utilized. We implemented a modified version of the American Lung Association’s Kickin Asthma curriculum. Self-report questionnaires assessing the key study variables were administered at baseline, at immediate postintervention, and five weeks after the intervention. There were no statistically significant differences at post-test, controlling for pre-test values, for any of the study variables between the intervention (n = 51) and comparison groups (n = 35). After collapsing across groups, however, there were statistically significant improvements following the intervention for knowledge, intention, selected behavior variables, and self-efficacy. The evaluation of this theory-based asthma education intervention demonstrates the positive impact this curriculum can have on a sample of asthmatic adolescents

Guest Artist Series:Tubalate

Center for the Performing Arts Wednesday Evening October 15, 2003 8:00p.m

Hot Rocks: Constraining the Thermal Conditions of the Mistastin Lake Impact Melt Deposits Using Zircon Grain Microstructures

The production of superheated melt during hypervelocity impact events has been proposed to be a common occurrence on terrestrial planetary bodies. Recent direct evidence of superheated impact melt temperatures exceeding \u3e2370°C from the Kamestastin (Mistastin Lake) impact structure, Canada, was based on a single impact glass sample. Such high superheated melt temperatures have strong implications for the evolution of crustal material, the thermal history of impact cratering events, and the rheology of impact melt. However, although widely predicted in previous studies, with the exception of the Mistastin Lake impact glass, there is little direct evidence for superheated temperatures in multiple settings across an impact structure. Therefore, an outstanding question is how heterogeneous are superheated conditions across a single impact structure. In this work, we analyze the crystallographic orientations and microstructures of zircon grains and the precursor parent phases of baddeleyite crystals, from four different samples representing the entire melt-bearing stratigraphy at Mistastin: an impact glass, a vesicular clast-poor impact melt rock, a clast-rich impact melt rock, and a glass-bearing impact breccia. Using electron microprobe analysis followed by electron backscatter diffraction, we discovered that four zircon grains with vermicular coronae of baddeleyite crystals from the impact glass contain evidence for a cubic zirconia precursor, indicative of temperature conditions \u3e2370°C. We also report evidence of superheating up to 1673°C in the glass-bearing impact breccia. In addition, we also report the first occurrence at Mistastin of the high-pressure zircon polymorph reidite and former reidite in granular neoblastic (FRIGN) zircon in grains from the glass-bearing impact breccia, implying minimum peak shocks from 30–40 GPa. The identification of superheating from two localities at Mistastin demonstrates (1) that superheating is not restricted solely to rapidly cooled impact melt rock samples and is therefore more distributed across impact structures, and (2) we can investigate the P-T evolution pathways of impact melt from different impact settings, providing a clearer picture of the thermal conditions and history of the impact structure