Overview and Initial Results of SAND-E: Semi-Autonomous Navigation for Detrital Environments

Unmanned aerial systems (UAS) and automated terrain analysis for science and navigation are new technologies for planetary exploration. The Mars Helicopter will fly with the Mars2020 rover, the Dragonfly quadcopter will explore Titan, and Soil Properties and Object Classification (SPOC) software will be used for path planning and navigation on the Mars2020 rover. Using an Argo J5 rover instrumented with stereo cameras and Autonomous Soil Assessment System (ASAS) software, and an off the shelf quadcopter, SAND-E tested the use of automated terrain analysis and UAS data for science operations in a Mars-analog environment in Iceland during July of 2019. Scientifically, we sought to determine changes in the physical and chemical properties of sediments along a glacial-fluvial-aeolian transport pathway. Operationally, we tested rover mission-like scenarios that included UAS images and classified terrain images. Here, we present the initial results for both the operations and science elements of the study. Site Selection: A goal of SAND-E is examine sorting and alteration of sediments in fluvial and aeolian environments in both mineral-dominated and glass-dominated basaltic settings. During the first year of the project we focused on a mineral-dominated environment. Selection of the location was based on prior publications that indicated our selected region had a greater abundance of crystalline sediments than other areas fluvial-aeolian settings in Iceland. Other criteria included the presence of both fluvial and aeolian landforms along a transport pathway such that the sediments in transport could be linked to their source rocks. We chose the Skjaldbreidauhraun glacial outwash plain, which sits at the base of Thrisjkull glacier. The site is 30 km north of Thingvellir National Park and ~2 hours from Reykjavik. The outwash plain is fed by two small catchments that drain from the base of the glacier and cut through hyaloclastite and shield volcano bedrock. The drainage progresses from steep alluvial fans near the glacier into a low-sloping fluvial braidplain that becomes confined by the Skjaldbreidur shield volcano and creates a shallow canyon cut into lava bedrock. The fluvial system was a typical braided alluvial environment composed pebble- and cobble-bedded longitudinal bars and sandy channel beds. The river remained active and fluctuated in response to diurnal runoff cycles near the glacier before disappearing into the sandy substrate downstream. The high concentration of suspended sediment in the river was evident by the cloudy water and the silt and clay-sized sediments that draped the channel beds after abandonment and created playas in the lowest sloping areas of the catchment. The entire fluvial system was affected by the winds generated by frontal systems and katabatic flows descending the glacier. This resulted in the formation of aeolian lag deposits and a wind-deflation plain where the fluvial system was not active. Wind ripples and drifts formed in abandoned fluvial channels from aeolian reworking of the sand-sized fluvial sediments. The silt- and clay-sized sediments found in fluvial channels, bar tops, and playas generated dust plumes during high wind events. Our operation sought to capture the variability in this system by sampling from the range of fluvial and aeolian features 6.3 km (proximal), 11.3 km (medial), and 14.4 km (distal) along the river from its origin at the base of glacier

Overview of SAND-E: Semi-Autonomous Navigation for Detrital Environments

Rovers are the state of the art for the exploration and detection of past habitability and life on other worlds. One of the most basic functions of a rover is terrain navigation. Information collected by the rover is used autonomously to mitigate terrain hazards such large rocks, while humans qualitatively assess hazardous geologic terrain such as soil type and degree of rock cover. Planetary scientists use the same information to select targets such as drill sites, and for basic scientific analysis such as characterization of rock outcrops. Although the data is complementary, data from terrain analysis for navigation and terrain analysis for scientific investigations are poorly integrated. The lack of integration creates science and operation inefficiencies that limit exploration of habitable environments. As new modes of exploration come online, such as unmanned aerial systems (UAS) (e.g., the Mars Helicopter Scout and Titan Dragonfly), a need exists to integrate terrain data and science analysis to improve operational and scientific outcomes during exploration. We present an overview of a project aimed at evaluating the effectiveness and capability rover and UAS-based semi-automated terrain analysis using the Automated Soil Assessment Systems (ASAS) developed by Mission Control Space Services for navigating, selecting targets for sampling, and characterizing mafic detrital sediments along glacio-fluvial-aeolian sand transport pathways in Iceland. We describe recent advances in automated terrain analysis in sandy environments and scientific uses of terrain assessment from sandy environments. We assess fluvial and aeolian terrains in Iceland and show how terrain analysis data can inform scientific characterization of these environments

Machine learning in clinical and epidemiological research: isn't it time for biostatisticians to work on it?

In recent years, there has been a widespread cross-fertilization between Medical Statistics and Machine Learning (ML) techniques

Multi-objective design optimization of compliant lunar wheels

The development of the wire-mesh wheel of the Apollo Lunar Roving Vehicle was realized through a time consuming trial and error design process, primarily driven by manufacturability and physical testing. Recent wheel development, motivated by renewed interest in lunar surface exploration, utilizes more sophisticated numerical simulation tools. However, many researchers still employ trial and error or parametric approaches to designing the wheels. This thesis proposes a systematic approach to the design optimization of compliant lunar wheels. The problem is decomposed into system and component level analyses. The system level analysis investigates the effect of elastic wheel behaviour on rover and mission performance metrics. This is realized by optimizing concept independent wheel design variables using multi-disciplinary models coupled with optimization algorithms. Wheel concepts are explored by prototyping and physical testing, as well as numerical modelling. The mobility performance metrics of cellular, segmented and iRings wheels are compared to a baseline rubber wheel. In the component level analysis, a multi-objective optimization algorithm is coupled with numerical simulations of wheel-ground interaction to find optimal cellular wheel designs. The effectiveness of the methodology to optimize cellular wheel concepts is verified, and the limitations of the approach examined. Finally, a discussion to extend the proposed methodology to alternative wheel concepts is provided.Le développement de la roue treillis métallique de l'Apollo Lunar Roving Vehicle a été réalisé par un processus d'essais et d'erreurs. Les récents développements de roues flexibles, motivé par un regain d'intérêt pour l'exploration lunaire, ont maintenant à leur disposition des outils de simulation numérique plus sophistiqués. Cependant, la majorité des chercheurs emploient toujours des méthodes expérimentales ou paramétriques pour développer leurs roues. Cette thèse propose une nouvelle approche systématique pour l'optimisation de concepts de roues lunaires flexibles. Le problème est décomposé en deux analyses se rapportant au niveau du système et celui des composantes. L'analyse au niveau du système étudie l'effet du comportement de la roue élastique sur des mesures de performance lors d'une mission du rover. Ceci est réalisé en optimisant les paramètres décrivant une roue flexible à l'aide de modèles multidisciplinaires. Différents concepts de roues sont explorés à l'aide de prototypes et d'essais physiques, ainsi que de modélisations numériques. La performance de chacun des concepts de roues flexibles cellulaires, iRings et segmentés sont comparées à un pneu standard. L'analyse au niveau des composantes effectue une optimisation multi-objective afin de déterminer, par le biais de simulations numériques, le concept optimal de roues flexibles cellulaires. L'efficacité de la méthodologie pour optimiser la roue cellulaire est ensuite vérifiée et les limites de cette approche sont examinées en détail. Finalement, une discussion sur l'application de la méthodologie proposée à des concepts de roues arbitraires est abordée

Intelligent velocity control of a bounding quadruped robot

The Platform for Ambulating Wheels (PAW) is a hybrid quadruped wheeled-legged robot that can bound, gallop, roll and brake at high speeds, and perform inclined turning. In previous work, the PAW’s controller used fixed touchdown and liftoff angles to achieve a stable bounding gait, and these angles were predetermined through an extensive trial and error process. In this work, an intelligent velocity controller is developed to allow the robot to autonomously find the touchdown and liftoff angles to bound at a desired velocity. This enables the robot to track desired velocities between 0.9 and 1.3 m/s, as shown in a Matlab-Adams co-simulation model of bounding. The controller also demonstrates tracking capabilities in the presence of minor terrain changes. To implement this controller on the physical platform, an Extended Kalman Filter (EKF) is developed to estimate the forward velocity of the robot required as a controller input. The EKF combines the data from an Inertial Measurement Unit and an estimate of forward velocity found kinematically using measurements from motor encoders and leg potentiometers. The accuracy of the EKF estimate of the forward velocity is validated in simulation and using high speed camera experiments. Finally, the intelligent controller is implemented and tested on the physical platform demonstrating adequate velocity tracking for set points between 0.9 m/s and 1.3 m/s, as well as transitions between set points in this range.Le « Platform for Ambulating Wheels » (PAW) est un robot quadrupède qui possède des roues au bout de ses quatre jambes. Sa combinaison de roues et jambes lui permet de rouler, d’effectuer des virages en inclinant son corps, de sauter, de bondir et de galloper. Dans les travaux précédents, le robot utilisait des angles fixes, trouvés par essais et erreurs, pour pouvoir bondir à une certaine vitesse. Un contrôleur intelligent capable de trouver les angles de façon autonome afin de suivre une vitesse prédéterminée est développé dans ce mémoire. Premièrement, la performance du contrôleur est évaluée dans une simulation MSC Adams et MATLAB démontrant les capacités à suivre des vitesses entre 0.9 et 1.3 m/s. Le contrôleur démontre une capacité à suivre la vitesse désirée même en présence de changement de terrain mineur.Ensuite, un filtre Kalman pour système non-linéaire est développé pour estimer la vitesse du robot, un paramètre nécessaire pour introduire le système de contrôle intelligent sur le robot. Les données d’une unité de mesure inertielle et une estimation de la vitesse par des équations cinématiques sont combinés dans le filtre pour estimer plus précisément la vitesse du robot. La précision du filtre est validée en comparant ses résultats contre ceux acquis en simulation et par une caméra à haute vitesse.Finalement, le contrôleur intelligent est évalué sur le robot en utilisant la vitesse estimée par le filtre Kalman. Les résultats expérimentaux du contrôleur démontre qu’il est capable de bien suivre des vitesses entre 0.9 et 1.3 m/s

Pachychoroid spectrum disease and choriocapillary flow analysis in patients with Cushing disease: an optical coherence tomography angiography study

Purpose To investigate the presence of pachychoroid spectrum disease (PSD) in patients with Cushing disease (CD) and to evaluate subfoveal choroidal thickness (SFCT) and choriocapillary flow using spectral domain OCT (SD-OCT) with the enhanced depth imaging (EDI) and optical coherence tomography angiography (OCT-A).Methods Thirty-two patients with CD and 32 age- and sex-matched healthy volunteers were enrolled in this observational study. All participants had a complete ophthalmic examination including SD-OCT with EDI and OCT-A, and were subjected to the Perceived Stress Scale test (PSS). All patients with CD had hormone test including 24-h urinary-free cortisol (UFC) and plasma adrenocorticotropic hormone (ACTH). We compared SFCT and choriocapillary vessel density (CVD) between the two groups and evaluated the presence of PSD. We investigated the association of hormone level, SFTC, CVD with the presence of CD; the association between the hormone level, SFTC, CVD, the CD disease activity, and duration with the presence of PSD in CD patients; and the association between SFTC and CVD with the hormone level, the CD disease activity, and duration in CD patients.Results Higher values of SFCT and CVD were associated with CD (beta: 0.028, 95% CI: 0.014; 0.041; beta: 0.912, 95%CI: 0.205; 1.62, respectively). Twelve patients with CD (37.5%) reported a PSD in at least one eye, whereas no subject was found in control group (p < 0.001); in particular, 11 CD patients (34%) presented pachychoroid pigment epitheliopathy (PPE) and 1 CD patient (3%) presented polypoidal choroidal vasculopathy/aneurysmal type 1 neovascularization (PCV/AT1). In patients with CD, a significant positive association between SFCT and PSD was found (beta: 0.010, 95% CI 0.001; 0.019).Conclusion A chronic state of hypercortisolism may have direct implications on the choroid. Patients with CD had higher SFCT values and a significant change in the choriocapillary flow compared to healthy controls. Moreover, PSD was observed only in CD patients

Quantification of Carbonic Anhydrase Inhibitors and Metabolites in Urine and Hair of Patients and Their Relatives

Carbonic anhydrase inhibitors (CAIs) are prescription drugs also used in doping to dilute urine samples and tamper with urinalyses. Dorzolamide, brinzolamide, and acetazolamide are prohibited by the World Anti-Doping Agency. Detecting CAIs and their metabolites in biological samples is crucial to documenting misuse in doping. We quantified dorzolamide, brinzolamide, acetazolamide, and their metabolites in the urine and hair of 88 patients under treatment for ocular hypertension or glaucoma. Samples of the patients’ relatives were analyzed to assess potential for accidental exposure. After washing, 25 mg hair was incubated with an acidic buffer at 100 °C for 1 h. After cooling and centrifugation, the supernatant was analyzed by ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Urine (100 μL) was diluted and centrifuged before UHPLC-MS/MS analysis. Run time was 8 min through a reverse-phase column with a mobile phase gradient. MS/MS analysis was performed in a multiple-reaction monitoring mode after positive electrospray ionization. Median urinary concentration was 245 ng/mL (IQR: 116.2–501 ng/mL) for dorzolamide, 81.1 ng/mL (IQR: 35.9–125.3 ng/mL) for N-deethyl-dorzolamide, 0.77 ng/mL (IQR: 0.64 ng/mL–0.84 ng/mL) for N-acetyl-dorzolamide, 38.9 ng/mL (IQR: 20.4–79.2 ng/mL) for brinzolamide, and 72.8 ng/mL (IQR: 20.7–437.3 ng/mL) for acetazolamide. Median hair concentration was 0.48 ng/mg (IQR: 0.1–0.98 ng/mg) for dorzolamide, 0.07 ng/mg (IQR: 0.06–0.08 ng/mg) for N-deethyl-dorzolamide, 0.40 ng/mL (IQR: 0.13–1.95 ng/mL) for brinzolamide. Acetazolamide was detected in only one hair sample. Dorzolamide and brinzolamide were detected in the urine of three and one relatives, respectively. Cutoff concentrations of urinary dorzolamide and brinzolamide are necessary to preclude false positives due to contamination or passive exposure. We reported the first concentrations of brinzolamide in hair

Mitral Valve Replacement with a Third Generation Porcine Valve: an Italian Multicentered Study

Postoperative outcomes of 3rd generation porcine bioprosthesis for mitral valve replacement (MVR) have been poorly addressed. The objective of this study was to perform an independent, retrospective, multicenter study on outcomes of patients undergoing MVR with Mosaic (Medtronic Inc., Minneapolis, MN) porcine bioposthesis