481 research outputs found
Reactive direction control for a mobile robot: A locust-like control of escape direction emerges when a bilateral pair of model locust visual neurons are integrated
Locusts possess a bilateral pair of uniquely identifiable visual neurons that respond vigorously to
the image of an approaching object. These neurons are called the lobula giant movement
detectors (LGMDs). The locust LGMDs have been extensively studied and this has lead to the
development of an LGMD model for use as an artificial collision detector in robotic applications.
To date, robots have been equipped with only a single, central artificial LGMD sensor, and this
triggers a non-directional stop or rotation when a potentially colliding object is detected. Clearly,
for a robot to behave autonomously, it must react differently to stimuli approaching from
different directions. In this study, we implement a bilateral pair of LGMD models in Khepera
robots equipped with normal and panoramic cameras. We integrate the responses of these LGMD
models using methodologies inspired by research on escape direction control in cockroaches.
Using ‘randomised winner-take-all’ or ‘steering wheel’ algorithms for LGMD model integration,
the khepera robots could escape an approaching threat in real time and with a similar
distribution of escape directions as real locusts. We also found that by optimising these
algorithms, we could use them to integrate the left and right DCMD responses of real jumping
locusts offline and reproduce the actual escape directions that the locusts took in a particular
trial. Our results significantly advance the development of an artificial collision detection and
evasion system based on the locust LGMD by allowing it reactive control over robot behaviour.
The success of this approach may also indicate some important areas to be pursued in future
biological research
Predator-Induced Vertical Behavior of a Ctenophore
Although many studies have focused on Mnemiopsis leidyi predation, little is known about the role of this ctenophore as prey when abundant in native and invaded pelagic systems. We examined the response of the ctenophore M. leidyi to the predatory ctenophore Beroe ovata in an experiment in which the two species could potentially sense each other while being physically separated. On average, M. leidyi responded to the predator’s presence by increasing variability in swimming speeds and by lowering their vertical distribution. Such behavior may help explain field records of vertical migration, as well as stratified and near-bottom distributions of M. leidyi
Forced Moves or Good Tricks in Design Space? Landmarks in the Evolution of Neural Mechanisms for Action Selection
This review considers some important landmarks in animal evolution, asking to what extent specialized action-selection mechanisms play a role in the functional architecture of different nervous system plans, and looking for “forced moves” or “good tricks” (see Dennett, D., 1995, Darwin’s Dangerous Idea, Penguin Books, London) that could possibly transfer to the design of robot control systems. A key conclusion is that while cnidarians (e.g. jellyfish) appear to have discovered some good tricks for the design of behavior-based control systems—largely lacking specialized selection mechanisms—the emergence of bilaterians may have forced the evolution of a central ganglion, or “archaic brain”, whose main function is to resolve conflicts between peripheral systems. Whilst vertebrates have many interesting selection substrates it is likely that here too the evolution of centralized structures such as the medial reticular formation and the basal ganglia may have been a forced move because of the need to limit connection costs as brains increased in size
An ontological approach to creating an Andean Weaving Knowledge Base
Andean textiles are products of one of the richest, oldest and continuous weaving traditions in the world. Understanding the knowledge and practice of textile production as a form of cultural heritage is particularly relevant in the Andean context due to erosion of clothing traditions, reuse of traditional textiles on commodities targeted at the tourism market, and loss of knowledge embedded in textile production. ``Weaving Communities of Practice'' was a pilot project that aimed to create a knowledge base of Andean weaving designed to contribute to curatorial practice and heritage policy. The research team gathered data on the chain of activities, instruments, resources, peoples, places and knowledge involved in the production of textiles, relating to over 700 textile samples. A major part of the project has been the modelling and representation of the knowledge of domain experts and information about the textile objects themselves in the form of an OWL ontology, and the development of a suite of search facilities to be supported by the ontology. This paper describes the research challenges faced in developing the ontology and search facilities, the methodology adopted, the design and implementation of the system, and the design and outcomes of a user evaluation of the system undertaken with a group of domain experts
Insect Bio-inspired Neural Network Provides New Evidence on How Simple Feature Detectors Can Enable Complex Visual Generalization and Stimulus Location Invariance in the Miniature Brain of Honeybees
This work was supported by a Human Frontier Science Program Grant RGP0022/2014 to LC and Queen Mary University of London Scholarship to MR. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Using Light to Improve Commercial Value
The plasticity of plant morphology has evolved to maximize reproductive fitness in response to prevailing environmental conditions. Leaf architecture elaborates to maximize light harvesting, while the transition to flowering can either be accelerated or delayed to improve an individual's fitness. One of the most important environmental signals is light, with plants using light for both photosynthesis and as an environmental signal. Plants perceive different wavelengths of light using distinct photoreceptors. Recent advances in LED technology now enable light quality to be manipulated at a commercial scale, and as such opportunities now exist to take advantage of plants' developmental plasticity to enhance crop yield and quality through precise manipulation of a crops' lighting regime. This review will discuss how plants perceive and respond to light, and consider how these specific signaling pathways can be manipulated to improve crop yield and quality
Development of the rhopalial nervous system in Aurelia sp.1 (Cnidaria, Scyphozoa)
We examined the development of the nervous system in the rhopalium, a medusa-specific sensory structure, in Aurelia sp.1 (Cnidaria, Scyphozoa) using confocal microscopy. The rhopalial nervous system appears primarily ectodermal and contains neurons immunoreactive to antibodies against tyrosinated tubulin, taurine, GLWamide, and FMRFamide. The rhopalial nervous system develops in an ordered manner: the presumptive gravity-sensing organ, consisting of the lithocyst and the touch plate, differentiates first; the “marginal center,” which controls swimming activity, second; and finally, the ocelli, the presumptive photoreceptors. At least seven bilaterally arranged neuronal clusters consisting of sensory and ganglion cells and their neuronal processes became evident in the rhopalium during metamorphosis to the medusa stage. Our analysis provides an anatomical framework for future gene expression and experimental studies of development and functions of scyphozoan rhopalia
Small brains, smart minds: vision, perception and 'cognition' in honeybees
Recent work is beginning to reveal that insects may not be the simple, reflexive creatures that they were once assumed to be. Honeybees, for example, can learn rather general features of flowers and landmarks, such as colour, orientation and symmetry, and apply them to distinguish between objects that they have never previously encountered. Bees exhibit "top-down" processing: that is, they are capable of using prior knowledge to detect poorly visible or camouflaged objects. Furthermore, bees can learn to navigate through labyrinths, to form complex associations and to acquire abstract concepts such,as "sameness" and "difference". All of these observations suggest that there is no hard dichotomy between invertebrates and vertebrates in the context of perception, learning and 'cognition'; and that brain size is not necessarily a reliable predictor of perceptual capacity
‘Your Tube’: the role of different diets in children who are gastrostomy fed: protocol for a mixed methods exploratory sequential study
Introduction Increasing numbers of children require having all, or part, of their nutritional intake via gastrostomy. More parents are using home-blended meals to feed their children, with many reporting beneficial effects such as improved gastro-oesophageal reflux, less constipation and less distress in their child. This study aims to identify the important outcomes of tube feeding in this population, compare the safety, outcomes and resource use of those on a home-blended diet compared with a formula diet and assess feasibility of long-term follow-up of children recruited to this study. Methods and analyses This is a mixed methods study of children (aged 6 months to 18 years) who are gastrostomy feed dependent recruited via general, community and specialist paediatric and dietetic services. Workstream 1 (WS1): a qualitative study involving semistructured interviews with parents (n~20) and young people (n~5–10), and focus groups with health professionals (n~25), will provide evidence of appropriate outcome measures and the feasibility/acceptability of proposed data collection methods for WS2. It will gather data on: desired outcomes of gastrostomy feeding, variability in diets and reasons; use of oral feeding; perceived benefits of the alternative diets, resources associated with gastrostomy feeding and safety issues. Data will be analysed using thematic analysis. WS2: a cohort study of 300 children who are gastrostomy fed. Data will be collected at months 0, 9 and 18 from parents, children (if appropriate) and clinicians using standardised measures and questionnaires developed specifically for the study. Data collected will include gastrointestinal symptoms, health and other outcomes (child, parent), dietary intake, anthropometry, healthcare usage, safety outcomes and resource use. Outcomes in the home-blended and formula groups will be compared using appropriate multiple regression analyses. Ethics and dissemination The study has been approved by a research ethics committee (REC reference: 19/ YH/0028). Results will be disseminated through publications and presentations for professionals and families
The OWL Reasoner Evaluation (ORE) 2015 Resources
The OWL Reasoner Evaluation (ORE) Competition is anannual competition (with an associated workshop) which pits OWL 2compliant reasoners against each other on various standard reasoningtasks over naturally occurring problems. The 2015 competition was thethird of its sort and had 14 reasoners competing in six tracks comprisingthree tasks (consistency, classication, and realisation) over two proles(OWL 2 DL and EL). In this paper, we outline the design of the competitionand present the infrastructure used for its execution: the corporaof ontologies, the competition framework, and the submitted systems.All resources are publicly available on the Web, allowing users to easilyre-run the 2015 competition, or reuse any of the ORE infrastructure forreasoner experiments or ontology analysis
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