INTEGRAL timing and localization performance

In this letter we report on the accuracy of the attitude, misalignment, orbit and time correlation which are used to perform scientific analyses of the INTEGRAL data. The boresight attitude during science pointings has an accuracy of 3 arcsec. At the center of the field, the misalignments have been calibrated leading to a location accuracy of 4 to 40 arcsec for the different instruments. The spacecraft position is known within 10 meters. The relative timing between instruments could be reconstructed within 10 microsec and the absolute timing within 40 microsec.Comment: 5 pages, 2 figures, accepted for publication in A+A letters, INTEGRAL special issu

Planck early results I : The Planck mission

Peer reviewe

Planck pre-launch status : The Planck mission

Peer reviewe

(AR)Scaling of standard metabolic rate in estuarine crocodiles Crocodylus porosus

Standard metabolic rate (SMR, ml O2 min−1) of captive Crocodylus porosus at 30 °C scales with body mass (kg) according to the equation, SMR = 1.01 M0.829, in animals ranging in body mass of 3.3 orders of magnitude (0.19–389 kg). The exponent is significantly higher than 0.75, so does not conform to quarter-power scaling theory, but rather is likely an emergent property with no single explanation. SMR at 1 kg body mass is similar to the literature for C. porosus and for alligators. The high exponent is not related to feeding, growth, or obesity of captive animals. The log-transformed data appear slightly curved, mainly because SMR is somewhat low in many of the largest animals (291–389 kg). A 3-parameter model is scarcely different from the linear one, but reveals a declining exponent between 0.862 and 0.798. A non-linear model on arithmetic axes overestimates SMR in 70 % of the smallest animals and does not satisfactorily represent the data.Roger S. Seymour, C.M. Gienger, Matthew L. Brien, Christopher R. Tracy, S. Charlie Manolis, Grahame J.W. Webb and Keith A. Christia

Disagreement-Aware Variable Impedance Control for Online Learning of Physical Human-Robot Cooperation Tasks

In order to make the coexistence between humans and robots a reality, we must understand how they may cooperate more effectively. Modern robots, empowered with reliable controls and advanced machine learning reasoning can face this challenge. In this article, we presented a Disagreement- Aware Variable Impedance (DAVI) Controller, where the robot stiffness is regulated as a function of the perceived disagreement with the human cooperator. We tested the algorithm on a 7 DoF Franka Emika Panda robot performing the learning of a pick&place task with continuous adaptation of the goal location and the via-points with human interactive corrections, triggered by our proposed approach. A validation study was conducted with 5 users in order to understand the reliability of the method.Paper presented at the workshop "Shared Autonomy in Physical Human-Robot Interaction: Adaptability and Trust" 23 May 2022Learning & Autonomous Contro

Energetic costs of digestion in Australian crocodiles

We measured standard metabolic rate (SMR) and the metabolic response to feeding in the Australian crocodiles, Crocodylus porosus and C. johnsoni. Both species exhibit a response that is characterised by rapidly increasing metabolism that peaks within 24h of feeding, a postfeeding metabolic peak (peak VO2) of 1.4–2.0 times SMR, and a return to baseline metabolism within 3–4 days after feeding. Postfeeding metabolism does not significantly differ between species, and crocodiles fed intact meals have higher total digestive costs (specific dynamic action; SDA) than those fed homogenised meals. Across a moret han100-fold range of body size (0.190 to 25.96 kg body mass),SMR,peak_VO2,and SDA all scale with body mass to an exponent of 0.85. Hatchling (<1 year old) C. porosus have unexpectedly high rates of resting metabolism, and this likely reflects the substantial energetic demands that accompany the rapid growth of young crocodiliansC.M. Gienger, Christopher R. Tracy, Matthew L. Brien, S. Charlie Manolis, Grahame J.W. Webb, Roger S. Seymour and Keith A. Christia

Alligators and crocodiles have high paracellular absorption of nutrients, but differ in digestive morphology and physiology

Much of what is known about crocodilian nutrition and growth has come from animals propagated in captivity, but captive animals from the families Crocodilidae and Alligatoridae respond differently to similar diets. Since there are few comparative studies of crocodilian digestive physiology to help explain these differences, we investigated young Alligator mississippiensis and Crocodylus porosus in terms of (1) gross and microscopic morphology of the intestine, (2) activity of the membrane-bound digestive enzymes aminopeptidase-N, maltase, and sucrase, and (3) nutrient absorption by carrier-mediated and paracellular pathways. We also measured gut morphology of animals over a larger range of body sizes. The two species showed different allometry of length and mass of the gut, with A. mississippiensis having a steeper increase in intestinal mass with body size, and C. porosus having a steeper increase in intestinal length with body size. Both species showed similar patterns of magnification of the intestinal surface area, with decreasing magnification from the proximal to distal ends of the intestine. Although A. mississippiensis had significantly greater surface-area magnification overall, a compensating significant difference in gut length between species meant that total surface area of the intestine was not significantly different from that of C. porosus. The species differed in enzyme activities, with A. mississippiensis having significantly greater ability to digest carbohydrates relative to protein than did C. porosus. These differences in enzyme activity may help explain the differences in performance between the crocodilian families when on artificial diets. Both A. mississippiensis and C. porosus showed high absorption of 3-O methyl D-glucose (absorbed via both carrier-mediated and paracellular transport), as expected. Both species also showed surprisingly high levels of L-glucose-uptake (absorbed paracellularly), with fractional absorptions as high as those previously seen only in small birds and bats. Analyses of absorption rates suggested a relatively high proportional contribution of paracellular (i.e., non-mediated) uptake to total uptake of nutrients in both species. Because we measured juveniles, and most paracellular studies to date have been on adults, it is unclear whether high paracellular absorption is generally high within crocodilians or whether these high values are specific to juveniles.Christopher R. Tracy, Todd J. McWhorter, C.M. Gienger, J. Matthias Starck, Peter Medley, S. Charlie Manolis, Grahame J.W. Webb, and Keith A. Christia

Interactive Imitation Learning of Object Movement Skills

Muehlig M, Steil JJ, Gienger M. Interactive Imitation Learning of Object Movement Skills. Autonomous Robots. 2012;32(2):97-114