Low-cost, multi-agent systems for planetary surface exploration

The use of off-the-shelf consumer electronics combined with top-down design methodologies have made small and inexpensive satellites, such as CubeSats, emerge as viable, low-cost and attractive space-based platforms that enable a range of new and exciting mission scenarios. In addition, to overcome some of the resource limitation issues encountered with these platforms, distributed architectures have emerged to enable complex tasks through the use of multiple low complexity units. The low-cost characteristics of such systems coupled with the distributed architecture allows for an increase in the size of the system beyond what would have been feasible with a monolithic system, hence widening the operational capabilities without significantly increasing the control complexity of the system. These ideas are not new for Earth orbiting devices, but excluding some distributed remote sensing architectures they are yet to be applied for the purpose of planetary exploration. Experience gained through large rovers demonstrates the value of in-situ exploration, which is however limited by the associated high-cost and risk. The loss of a rover can and has happened because of a number of possible failures: besides the hazards directly linked to the launch and journey to the target-body, hard landing and malfunctioning of parts are all threats to the success of the mission. To overcome these issues this paper introduces the concept of using off-the-shelf consumer electronics to deploy a low-cost multi-rover system for future planetary surface exploration. It is shown that such a system would significantly reduce the programmatic-risk of the mission (for example catastrophic failure of a single rover), while exploiting the inherent advantages of cooperative behaviour. These advantages are analysed with a particular emphasis put upon the guidance, navigation and control of such architectures using the method of artificial potential field. Laboratory tests on multi-agent robotic systems support the analysis. Principal features of the system are identified and the underlying advantages over a monolithic single-agent system highlighted

ForgetMeNot: Active Reminder Entry Support for Adults with Acquired Brain Injury

Smartphone reminding apps can compensate for memory impairment after acquired brain injury (ABI). In the absence of a caregiver, users must enter reminders themselves if the apps are going to help them. Poor memory and apathy associated with ABI can result in failure to initiate such configuration behaviour and the benefits of reminder apps are lost. ForgetMeNot takes a novel approach to address this problem by periodically encouraging the user to enter reminders with unsolicited prompts (UPs). An in situ case study investigated the experience of using a reminding app for people with ABI and tested UPs as a potential solution to initiating reminder entry. Three people with severe ABI living in a post-acute rehabilitation hospital used the app in their everyday lives for four weeks to collect real usage data. Field observations illustrated how difficulties with motivation, insight into memory difficulties and anxiety impact reminder app use in a rehabilitation setting. Results showed that when 6 UPs were presented throughout the day, reminder-setting increased, showing UPs are an important addition to reminder applications for people with ABI. This study demonstrates that barriers to technology use can be resolved in practice when software is developed with an understanding of the issues experienced by the user group

Aiming for the top corner: Measuring top-quark pair production in association with additional jets in highly boosted events using the ATLAS detector

Since beginning operations in 2010 the Large Hadron Collider (LHC) has consistently pushed the boundaries of high energy physics and provided a wealth of proton-proton collision events. Due to the high centre of mass energies achieved, and the QCD nature of protonproton collisions, the LHC is particularly suited to the production of top-quarks, resulting in the apt nickname of ’top factory’. This thesis outlines the process of making state-of-the-art precision measurements of the top-quark pair production cross-section in events with a high energy top-quark and additional radiation, using data recorded by the ATLAS detector at the LHC from 2015 to 2018. Focus is put on comparing measured values with different QCD predictions showcasing how suited current theories are to estimating complex, multi-scale, and above leading-order processes. Both single and double-differential cross-section measurements as functions of various event kinematic properties are presented with results derived from proton-proton collisions, at a centre-of-mass energy of 13 TeV. Additionally a single differential measurement is used to set limits on new physics using an effective field theory framework

Active Reward Learning for Co-Robotic Vision Based Exploration in Bandwidth Limited Environments

We present a novel POMDP problem formulation for a robot that must autonomously decide where to go to collect new and scientifically relevant images given a limited ability to communicate with its human operator. From this formulation we derive constraints and design principles for the observation model, reward model, and communication strategy of such a robot, exploring techniques to deal with the very high-dimensional observation space and scarcity of relevant training data. We introduce a novel active reward learning strategy based on making queries to help the robot minimize path "regret" online, and evaluate it for suitability in autonomous visual exploration through simulations. We demonstrate that, in some bandwidth-limited environments, this novel regret-based criterion enables the robotic explorer to collect up to 17% more reward per mission than the next-best criterion.Comment: 7 pages, 4 figures; accepted for presentation in IEEE Int. Conf. on Robotics and Automation, ICRA '20, Paris, France, June 202

Probability and visual aids for assessing intervention effectiveness in single-case designs: A field test

Single-case data analysis still relies heavily on visual inspection and, at the same time, it is not clear to what extent the results of different quantitative procedures converge in identifying an intervention effect and its magnitude when applied to the same data; this is the type of evidence provided here for two procedures. One of the procedures, included due to the importance of providing objective criteria to visual analysts, is a visual aid fitting and projecting split-middle trend while taking into account data variability. The other procedure converts several different metrics into probabilities making their results comparable. In the present study we study to what extend these two procedures coincide in the magnitude of intervention effect taking place in a set of studies stemming from a recent meta-analysis. The procedures concur to a greater extent with the values of the indices computed and with each other and, to a lesser extent, with our own visual analysis. For the distinctions smaller and larger effects the probability-based approach seems somewhat better suited. Moreover, the results of the field test suggest that the latter is a reasonably good mechanism for translating different metrics into similar labels. User friendly R code is provided for promoting the use of the visual aid, together with a quantification based on nonoverlap and the label provided by the probability approach

A discussion of alternatives for establishing empirical benchmarks for interpreting single-case effect sizes

In this paper we reflect on the numerous calls for the development of benchmarks for interpreting effect size indices, reviewing several possibilities. Such benchmarks are aimed to provide criteria so that analysts can judge whether the size of the effect observed is rather 'small', 'medium' or 'large'. The context of this discussion is single-case experimental designs, for which a great variety of procedures have been proposed, with their different nature (e.g., being based on amount of overlap vs. a standardized mean difference) posing challenges to interpretation. For each of the alternatives discussed we point at their strengths and limitations. We also comment how such empirical benchmarks can be obtained, usually b methodologists, and illustrate how these benchmarks can be used by applied researchers willing to have more evidence on the magnitude of effect observed and not only whether an effect is present or not. One of the alternatives discussed is a proposal we make in the current paper. Although it has certain limitations, as all alternatives do, we consider that it is worth discussing it and the whole set of alternatives in order to advance in interpreting effect sizes, now that computing and reporting their numerical values is (or is expected to be) common practice

Technological memory aid use by people with acquired brain injury

Evans, Wilson, Needham, and Brentnall (2003) investigated memory aid use by people with acquired brain injury (ABI) and found little use of technological memory aids. The present study aims to investigate use of technological and other memory aids and strategies 10 years on, and investigate what predicts use. People with ABI and self-reported memory impairments (n = 81) completed a survey containing a memory aid checklist, demographic questions and memory questionnaires. Chi-square analysis showed that 10 of 18 memory aids and strategies were used by significantly more people in the current sample than in Evans et al. (2003). The most commonly used strategies were leaving things in noticeable places (86%) and mental retracing of steps (77%). The most commonly used memory aids were asking someone to remind you (78%), diaries (77%), lists (78%), and calendars (79%) and the most common technologies used were mobile phone reminders (38%) and alarms/timers (38%). Younger people who used more technology prior to their injury and who use more non-technological memory aids currently were more likely to use technology. Younger people who used more memory aids and strategies prior to their injury and who rated their memory as poorer were more likely to use all types of memory aids and strategies

Synthesis and fluorescent properties of β-pyridyl α-amino acids

The preparation of a new class of β-pyridyl α-amino acid is described using a highly regioselective, ytterbium-catalyzed hetero Diels-Alder reaction of enones with vinyl ethers followed by a modified Knoevenagel-Stobbe reaction as the key heterocycle forming steps. Investigation of the properties and applications of these amino acids showed that they could be utilized in solid phase peptide synthesis for the preparation of a biologically relevant hexapeptide, while pyridines bearing electron-rich substituents exhibited strongly fluorescent properties with high quantum yields and MegaStokes shifts. A solvatochromic study with the most fluorogenic amino acid, a p-methoxyphenyl analogue revealed that this charge-transfer based chromophore is highly sensitive to solvent polarity with a bathochromic shift of 115 nm on changing from THF to phosphate-buffered saline

Solid-phase synthesis of oxetane modified peptides

Solid-phase peptide synthesis (SPPS) is used to create peptidomimetics in which one of the backbone amide C=O bonds is replaced by a four-membered oxetane ring. The oxetane containing dipeptide building blocks are made in three steps in solution, then integrated into peptide chains by conventional Fmoc SPPS. This methodology is used to make a range of peptides in high purity including backbone modified derivatives of the nonapeptide bradykinin and Met- and Leu-enkephalin