Axel: A Minimalist Tethered Rover for Exploration of Extreme Planetary Terrains

Recent scientific findings suggest that some of the most interesting sites for future exploration of planetary surfaces lie in terrains that are currently inaccessible to conventional robotic rovers. To provide robust and flexible access to these terrains, we have been developing Axel, the robotic rover. Axel is a lightweight two-wheeled vehicle that can access steep terrains and negotiate relatively large obstacles because of its actively managed tether and novel wheel design. This article reviews the Axel system and focuses on those system components that affect Axel's steep terrain mobility. Experimental demonstrations of Axel on sloped and rocky terrains are presented

Axel Robotic Platform for Crater and Extreme Terrain Exploration

To be able to conduct science investigations on highly sloped and challenging terrains, it is necessary to deploy science payloads to such locations and collect and process in situ samples. A tethered robotic platform has been developed that is capable of exploring very challenging terrain. The Axel rover is a symmetrical rover that is minimally actuated, can traverse arbitrary paths, and operate upside-down or right-side up. It can be deployed from a larger platform (rover, lander, or aerobot) or from a dual Axel configuration. Axel carries and manages its own tether, reducing damage to the tether during operations. Fundamentally, Axel is a two-wheeled rover with a symmetric body and a trailing link. Because the primary goal is minimal complexity, this version of the Axel rover uses only four primary actuators to control its wheels, tether, and a trailing link. A fifth actuator is used for level winding of tether onto Axel s spool

Risk of adverse events in patients prescribed long‐term opioids: a cohort study in the UK Clinical Practice Research Datalink

Background Long‐term opioid prescribing for musculoskeletal pain is controversial due to uncertainty regarding effectiveness and safety. This study examined the risks of a range of adverse events in a large cohort of patients prescribed long‐term opioids using the UK Clinical Practice Research Datalink. Methods Patients with musculoskeletal conditions starting a new long‐term opioid episode (defined as ≥3 opioid prescriptions within 90 days) between 2002 and 2012 were included. Primary outcomes: major trauma and intentional overdose (any). Secondary outcomes: addiction (any), falls, accidental poisoning, attempted suicide/self‐harm, gastrointestinal pathology and bleeding, and iron deficiency anaemia. “Control” outcomes (unrelated to opioid use): incident eczema and psoriasis. Results A total of 98,140 new long‐term opioids users (median age 61, 41% male) were followed for (median) 3.4 years. Major trauma risk increased from 285 per 10,000 person‐years without long‐term opioids to 369/10,000 for a long‐term opioid episode (<20 mg MED), 382/10,000 (20–50 mg MED), and 424/10,000 (≥50 mg MED). Adjusted hazard ratios were 1.09 (95% CI; 1.04, 1.14 for <20 mg MED vs. not being in an episode of long‐term prescribing), 1.24 (95% CI; 1.16, 1.32: 20–50 mg MED) and 1.34 (95% CI; 1.20, 1.50: ≥50 mg MED). Significant dose‐dependent increases in the risk of overdose (any type), addiction, falls, accidental poisoning, gastrointestinal pathology, and iron deficiency anaemia were also found. Conclusions Patients prescribed long‐term opioids are vulnerable to dose‐dependent serious adverse events. Opioid prescribing should be reviewed before long‐term use becomes established, and periodically thereafter to ensure that patients are not being exposed to increased risk of harm, which is not balanced by therapeutic benefit. Significance Long‐term opioid use is associated with serious adverse events such as major trauma, addiction and overdose. The risk increases with higher opioid doses. Opioid prescribing should be reviewed before long‐term use becomes established, and periodically thereafter to assess ongoing effectiveness

Axel Mobility Platform for Steep Terrain Excursions and Sampling on Planetary Surfaces

The recent discovery of bright new deposits in two crater gullies on Mars suggests that water still flows in brief spurts on Mars. In this paper, we will present the Axel rover (Figure 1) that was developed to access and sample such deposits on the inside of steep crater walls. Axel is a tethered rover that can be a payload on a lander or a larger rover. The primary features of Axel are its minimal complexity and robustness to the treacherous terrain of sites that are of scientific interest. Using a symmetrical design with three actuators, Axel is capable of operating upside down and right side up, enabling it to descend over crater promontories. With its actuated trailing link, Axel can operate on both flat and sloped terrains. Using a sampling device mounted on the trailing link, Axel can collect and store terrain samples and return to its host platform for detailed scientific sample analysis. We will present our preliminary results that demonstrated Axel's ability to traverse both flat and sloped rocky terrain including 90° vertical cliffs and collecting soil samples on slopes ranging from 10° - 40° in the JPL Mars Yard

Validation of full-wave simulations for mode conversion of waves in the ion cyclotron range of frequencies with phase contrast imaging in Alcator C-Mod

Mode conversion of fast waves in the ion cyclotron range of frequencies (ICRF) is known to result in current drive and flow drive under optimised conditions, which may be utilized to control plasma profiles and improve fusion plasma performance. To describe these processes accurately in a realistic toroidal geometry, numerical simulations are essential. Quantitative comparison of these simulations and the actual experimental measurements is important to validate their predictions and to evaluate their limitations. The phase contrast imaging (PCI) diagnostic has been used to directly detect the ICRF waves in the Alcator C-Mod tokamak. The measurements have been compared with full-wave simulations through a synthetic diagnostic technique. Recently, the frequency response of the PCI detector array on Alcator C-Mod was recalibrated, which greatly improved the comparison between the measurements and the simulations. In this study, mode converted waves for D-{superscript 3]He and D-H plasmas with various ion species compositions were re-analyzed with the new calibration. For the minority heating cases, self-consistent electric fields and a minority ion distribution function were simulated by iterating a full-wave code and a Fokker-Planck code. The simulated mode converted wave intensity was in quite reasonable agreement with the measurements close to the antenna, but discrepancies remain for comparison at larger distances.United States. Department of Energy (Grant DE-FG02- 94ER54235

Preface

Reproductive tract bleeding in women is a naturally occurring event during menstruation and childbirth. In women with menorrhagia, however, congenital bleeding disorders historically have been underdiagnosed. This consensus is intended to allow physicians to better recognize bleeding disorders as a cause of menorrhagia and consequently offer effective disease-specific therapies. © 2009 Mosby, Inc. All rights reserved

Comprehensive analyses of DNA repair pathways, smoking and bladder cancer risk in Los Angeles and Shanghai

Tobacco smoking is a bladder cancer risk factor and a source of carcinogens that induce DNA damage to urothelial cells. Using data and samples from 988 cases and 1,004 controls enrolled in the Los Angeles County Bladder Cancer Study and the Shanghai Bladder Cancer Study, we investigated associations between bladder cancer risk and 632 tagSNPs that comprehensively capture genetic variation in 28 DNA repair genes from four DNA repair pathways: base excision repair (BER), nucleotide excision repair (NER), non-homologous end-joining (NHEJ) and homologous recombination repair (HHR). Odds ratios (ORs) and 95% confidence intervals (CIs) for each tagSNP were corrected for multiple testing for all SNPs within each gene using pACT and for genes within each pathway and across pathways with Bonferroni. Gene and pathway summary estimates were obtained using ARTP. We observed an association between bladder cancer and POLB rs7832529 (BER) (pACT = 0.003; ppathway = 0.021) among all, and SNPs in XPC (NER) and OGG1 (BER) among Chinese men and women, respectively. The NER pathway showed an overall association with risk among Chinese males (ARTP NER p = 0.034). The XRCC6 SNP rs2284082 (NHEJ), also in LD with SREBF2, showed an interaction with smoking (smoking status interaction pgene = 0.001, ppathway = 0.008, poverall = 0.034). Our findings support a role in bladder carcinogenesis for regions that map close to or within BER (POLB, OGG1) and NER genes (XPC). A SNP that tags both the XRCC6 and SREBF2 genes strongly modifies the association between bladder cancer risk and smoking

Limits on Gravitational-Wave Emission from Selected Pulsars Using LIGO Data

We place direct upper limits on the amplitude of gravitational waves from 28 isolated radio pulsars by a coherent multidetector analysis of the data collected during the second science run of the LIGO interferometric detectors. These are the first direct upper limits for 26 of the 28 pulsars. We use coordinated radio observations for the first time to build radio-guided phase templates for the expected gravitational-wave signals. The unprecedented sensitivity of the detectors allows us to set strain upper limits as low as a few times 10^(-24). These strain limits translate into limits on the equatorial ellipticities of the pulsars, which are smaller than 10^(-5) for the four closest pulsars

Integrated information increases with fitness in the evolution of animats

One of the hallmarks of biological organisms is their ability to integrate disparate information sources to optimize their behavior in complex environments. How this capability can be quantified and related to the functional complexity of an organism remains a challenging problem, in particular since organismal functional complexity is not well-defined. We present here several candidate measures that quantify information and integration, and study their dependence on fitness as an artificial agent ("animat") evolves over thousands of generations to solve a navigation task in a simple, simulated environment. We compare the ability of these measures to predict high fitness with more conventional information-theoretic processing measures. As the animat adapts by increasing its "fit" to the world, information integration and processing increase commensurately along the evolutionary line of descent. We suggest that the correlation of fitness with information integration and with processing measures implies that high fitness requires both information processing as well as integration, but that information integration may be a better measure when the task requires memory. A correlation of measures of information integration (but also information processing) and fitness strongly suggests that these measures reflect the functional complexity of the animat, and that such measures can be used to quantify functional complexity even in the absence of fitness data.Comment: 27 pages, 8 figures, one supplementary figure. Three supplementary video files available on request. Version commensurate with published text in PLoS Comput. Bio