39 research outputs found
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Evolved transistor array robot controllers
For the first time a field programmable transistor array (FPTA) was used to evolve robot control circuits directly in analog hardware. Controllers were successfully incrementally evolved for a physical robot engaged in a series of visually guided behaviours, including finding a target in a complex environment where the goal was hidden from most locations. Circuits for recognising spoken commands were also evolved and these were used in conjunction with the controllers to enable voice control of the robot, triggering behavioural switching. Poor quality visual sensors were deliberately used to test the ability of evolved analog circuits to deal with noisy uncertain data in realtime. Visual features were coevolved with the controllers to automatically achieve dimensionality reduction and feature extraction and selection in an integrated way. An efficient new method was developed for simulating the robot in its visual environment. This allowed controllers to be evaluated in a simulation connected to the FPTA. The controllers then transferred seamlessly to the real world. The circuit replication issue was also addressed in experiments where circuits were evolved to be able to function correctly in multiple areas of the FPTA. A methodology was developed to
analyse the evolved circuits which provided insights into their operation. Comparative experiments demonstrated the superior evolvability of the transistor array medium
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Recent advances in evolutionary and bio-inspired adaptive robotics: exploiting embodied dynamics
This paper explores current developments in evolutionary and bio-inspired approaches to autonomous robotics, concentrating on research from our group at the University of Sussex. These developments are discussed in the context of advances in the wider fields of adaptive and evolutionary approaches to AI and robotics, focusing on the exploitation of embodied dynamics to create behaviour. Four case studies highlight various aspects of such exploitation. The first exploits the dynamical properties of a physical electronic substrate, demonstrating for the first time how component-level analog electronic circuits can be evolved directly in hardware to act as robot controllers. The second develops novel, effective and highly parsimonious navigation methods inspired by the way insects exploit the embodied dynamics of innate behaviours. Combining biological experiments with robotic modeling, it is shown how rapid route learning can be achieved with the aid of navigation-specific visual information that is provided and exploited by the innate behaviours. The third study focuses on the exploitation of neuromechanical chaos in the generation of robust motor behaviours. It is demonstrated how chaotic dynamics can be exploited to power a goal-driven search for desired motor behaviours in embodied systems using a particular control architecture based around neural oscillators. The dynamics are shown to be chaotic at all levels in the system, from the neural to the embodied mechanical. The final study explores the exploitation of the dynamics of brain-body-environment interactions for efficient, agile flapping winged flight. It is shown how a multi-objective evolutionary algorithm can be used to evolved dynamical neural controllers for a simulated flapping wing robot with feathered wings. Results demonstrate robust, stable, agile flight is achieved in the face of random wind gusts by exploiting complex asymmetric dynamics partly enabled by continually changing wing and tail morphologies
The varved succession of Crawford Lake, Milton, Ontario, Canada as a candidate Global boundary Stratotype Section and Point for the Anthropocene series
An annually laminated succession in Crawford Lake, Ontario, Canada is proposed as the Global boundary Stratotype Section and Point (GSSP) for the Anthropocene as a series/epoch with a base dated at 1950 CE. Varve couplets of organic matter capped by calcite precipitated each summer in alkaline surface waters reflect environmental change at global to local scales. Spheroidal carbonaceous particles and nitrogen isotopes record an increase in fossil fuel combustion in the early 1950s, coinciding with fallout from nuclear and thermonuclear testing—239+240Pu and 14C:12C, the latter more than compensating for the effects of old carbon in this dolomitic basin. Rapid industrial expansion in the North American Great Lakes region led to enhanced leaching of terrigenous elements by acid precipitation during the Great Acceleration, and calcite precipitation was reduced, producing thin calcite laminae around the GSSP that is marked by a sharp decline in elm pollen (Dutch Elm disease). The lack of bioturbation in well-oxygenated bottom waters, supported by the absence of fossil pigments from obligately anaerobic purple sulfur bacteria, is attributed to elevated salinities and high alkalinity below the chemocline. This aerobic depositional environment, unusual in a meromictic lake, inhibits the mobilization of 239Pu, the proposed primary stratigraphic guide for the Anthropocene
Gripping Evolvable Hardware - Part II Computer Science
this dissertation and the work described in it are my own work, unaided except as may be specified below, and that the dissertation does not contain material that has already been used to any substantial extent for a comparable purpose. Signed Date ii Contents
Reconstructing the diets of Greek Byzantine populations (6th–15th centuries AD) using carbon and nitrogen stable isotope ratios
Documentary evidence and artistic representations have traditionally served as the primary sources of information about Byzantine diet. According to these sources, Byzantine diet was based on grain (primarily wheat and barley), oil, and wine, supplemented with legumes, dairy products, meat, and marine resources. Here, we synthesize and compare the results of stable isotope ratio analyses of eight Greek Byzantine populations (6th-15th centuries AD) from throughout Greece. The δ(13) C and δ(15) N values are tightly clustered, suggesting that all of these populations likely consumed a broadly similar diet. Both inland and coastal Byzantine populations consumed an essentially land-based C(3) diet, significant amounts of animal protein, and possibly some C(4) plants, while no evidence of a general dependence on low-δ(15) N legumes was observed. One interesting result observed in the isotopic data is the evidence for the consumption of marine protein at both coastal sites (a reasonable expectation given their location) and for some individuals from inland sites. This pattern contrasts with previous isotopic studies mainly on prehistoric Greek populations, which have suggested that marine species contributed little, or not at all, to the diet. The possibility that fasting practices contributed to marine protein consumption in the period is discussed, as are possible parallels with published isotope data from western European medieval sites.status: publishe
The Autophagy-Related Beclin‑1 Protein Requires the Coiled-Coil and BARA Domains To Form a Homodimer with Submicromolar Affinity
Beclin-1
(BECN1) is an essential component of macroautophagy. This
process is a highly conserved survival mechanism that recycles damaged
cellular components or pathogens by encasing them in a bilayer vesicle
that fuses with a lysosome to allow degradation of the vesicular contents.
Mutations or altered expression profiles of BECN1 have been linked
to various cancers and neurodegenerative diseases. Viruses, including
HIV and herpes simplex virus 1 (HSV-1), are also known to specifically
target BECN1 as a means of evading host defense mechanisms. Autophagy
is regulated by the interaction between BECN1 and Bcl-2, a pro-survival
protein in the apoptotic pathway that stabilizes the BECN1 homodimer.
Disruption of the homodimer by phosphorylation or competitive binding
promotes autophagy through an unknown mechanism. We report here the
first recombinant synthesis (3–5 mg/L in an <i>Escherichia
coli</i> culture) and characterization of full-length, human
BECN1. Our analysis reveals that full-length BECN1 exists as a soluble
homodimer (<i>K</i><sub>D</sub> ∼ 0.45 μM)
that interacts with Bcl-2 (<i>K</i><sub>D</sub> = 4.3 ±
1.2 μM) and binds to lipid membranes. Dimerization is proposed
to be mediated by a coiled-coil region of BECN1. A construct lacking
the C-terminal BARA domain but including the coiled-coil region exhibits
a homodimer <i>K</i><sub>D</sub> 3.5-fold weaker than that
of full-length BECN1, indicating that both the BARA domain and the
coiled-coil region of BECN1 contribute to dimer formation. Using site-directed
mutagenesis, we show that residues at the C-terminus of the coiled-coil
region previously shown to interact with the BARA domain play a key
role in dimerization and mutations weaken the interface by ∼5-fold