Evolving Gaits for Damage Control in a Hexapod Robot

Autonomous robots are increasingly used in remote and hazardous environments, where damage to sensory-actuator systems cannot be easily repaired. Such robots must therefore have controllers that continue to function effectively given unexpected malfunctions and damage to robot morphology. This study applies the Intelligent Trial and Error (IT&E) algorithm to adapt hexapod robot control to various leg failures and demonstrates the IT&E map-size parameter as a critical parameter in influencing IT&E adaptive task performance. We evaluate robot adaptation for multiple leg failures on two different map-sizes in simulation and validate evolved controllers on a physical hexapod robot. Results demonstrate a trade-off between adapted gait speed and adaptation duration, dependent on adaptation task complexity (leg damage incurred), where map-size is crucial for generating behavioural diversity required for adaptation

Differentially Addressable Cavities within Metal-Organic Cage-Cross-Linked Polymeric Hydrogels

Here we report a new class of hydrogels formed by polymers that are cross-linked through subcomponent self-assembled metal–organic cages. Selective encapsulation of guest molecules within the cages creates two distinct internal phases within the hydrogel, which allows for contrasting release profiles of related molecules depending on their aptitude for encapsulation within the cages. The hydrogels were fabricated into microparticles via a droplet-based microfluidic approach and proved responsive to a variety of stimuli, including acid and competing amine or aldehyde subcomponents, allowing for the triggered release of cargo

Hilft das zahnmedizinische Bonussystem den stationär Pflegebedürftigen?

Zusammenfassung: Die Mundgesundheit bei Pflegebedürftigen ist mangelhaft. Zufällig ausgewählte Pflegebedürftige (Berlin n=75, Nordrhein-Westfalen n=94, Sachsen n=73) aus 30 stationären Pflegeeinrichtungen wurden u.a. zu ihrem Verhalten der zahnmedizinischen Inanspruchnahme und der Nutzung ihres zahnmedizinischen Bonusheftes (zBH) befragt. Von 242Befragten (Median: 82Jahre, Range: 43-100Jahre, Frauen: 78,5%) besaßen nur 18,6% ein zBH, dabei gab es keine signifikanten geschlechts- und altersspezifischen Unterschiede. Regionale Unterschiede waren signifikant (Berlin 5,3%, Nordrhein-Westfalen 18,1%, Sachsen 32,9%; χ2-Test p<0,01). Die Zahnzahl war bei Bonusheftinhabern größer (Mann-Whitney-Test p=0,01), die Zeitspanne zum letzten Zahnarztbesuch geringer (p<0,01). Von den Bonusheftinhabern gaben 18,6% an, den Zahnarzt länger als 12Monate nicht aufgesucht zu haben (stationär Pflegebedürftige ohne Bonusheft 51,3%). Als Beitrag zur Qualitätssicherung, zur oralen Infektionskontrolle sowie zur Verbesserung der mundbezogenen und allgemeinen Lebensqualität wird die regelmäßige jährliche Durchführung zahnmedizinischer Reihenuntersuchungen mit dem Führen eines zBH für jeden Bewohner vorgeschlage

Carbon Sequestration in Managed Temperate Coniferous Forests Under Climate Change

Management of temperate forests has the potential to increase carbon sinks and mitigate climate change. However, those opportunities may be confounded by negative climate change impacts. We therefore need a better understanding of climate change alterations to temperate forest carbon dynamics before developing mitigation strategies. The purpose of this project was to investigate the interactions of species composition, fire, management, and climate change in the Copper–Pine Creek valley, a temperate coniferous forest with a wide range of growing conditions. To do so, we used the LANDIS-II modelling framework including the new Forest Carbon Succession extension to simulate forest ecosystems under four different productivity scenarios, with and without climate change effects, until 2050. Significantly, the new extension allowed us to calculate the net sector productivity, a carbon accounting metric that integrates aboveground and belowground carbon dynamics, disturbances, and the eventual fate of forest products. The model output was validated against literature values. The results implied that the species optimum growing conditions relative to current and future conditions strongly influenced future carbon dynamics. Warmer growing conditions led to increased carbon sinks and storage in the colder and wetter ecoregions but not necessarily in the others. Climate change impacts varied among species and site conditions, and this indicates that both of these components need to be taken into account when considering climate change mitigation activities and adaptive management. The introduction of a new carbon indicator, net sector productivity, promises to be useful in assessing management effectiveness and mitigation activities

The Environment and Body-Brain Complexity

An open question for both natural and artificial evolutionary systems is how, and under what environmental and evolutionary conditions complexity evolves. This study investigates the impact of increasingly complex task environments on the evolution of robot complexity. Specifically, the impact of evolving body-brain couplings on locomotive task performance, where robot evolution was directed by either body-brain exploration (novelty search) or objective-based (fitness function) evolutionary search. Results indicated that novelty search enabled the evolution of increased robot body-brain complexity and efficacy given specific environment conditions. The key contribution is thus the demonstration that body-brain exploration is suitable for evolving robot complexity that enables high fitness robots in specific environments

Rates of population differentiation and speciation are decoupled in sea snakes

Comparative phylogeography can inform many macroevolutionary questions, such as whether species diversification is limited by rates of geographical population differentiation. We examined the link between population genetic structure and species diversification in the fully aquatic sea snakes (Hydrophiinae) by comparing mitochondrial phylogeography across northern Australia in 16 species from two closely related clades that show contrasting diversification dynamics. Contrary to expectations from theory and several empirical studies, our results show that, at the geographical scale studied here, rates of population differentiation and speciation are not positively linked in sea snakes. The eight species sampled from the rapidly speciating Hydrophis clade have weak population differentiation that lacks geographical structure. By contrast, all eight sampled Aipysurus-Emydocephalus species show clear geographical patterns and many deep intraspecific splits, but have threefold slower speciation rates. Alternative factors, such as ecological specialization, species duration and geographical range size, may underlie rapid speciation in sea snakes.Charlotte R. Nitschke, Mathew Hourston, Vinay Udyawer and Kate L. Sander

Chromosome 1p13 genetic variants antagonize the risk of myocardial infarction associated with high ApoB serum levels

PMCID: PMC3480949This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited

Thixotropy in macroscopic suspensions of spheres

An experimental study of the viscosity of a macroscopic suspension, i.e. a suspension for which Brownian motion can be neglected, under steady shear is presented. The suspension is prepared with a high packing fraction and is density-matched in a Newtonian carrier fluid. The viscosity of the suspension depends on the shear rate and the time of shearing. It is shown for the first time that a macroscopic suspension shows thixotropic viscosity, i.e. shear-thinning with a long relaxation time as a unique function of shear. The relaxation times show a systematic decrease with increasing shear rate. These relaxation times are larger when decreasing the shear rates, compared to those observed after increasing the shear. The time scales involved are about 10000 times larger than the viscous time scale and about 1000 times smaller than the thermodynamic time scale. The structure of the suspension at the outer cylinder of a viscometer is monitored with a camera, showing the formation of a hexagonal structure. The temporal decrease of the viscosity under shear coincides with the formation of this hexagonal pattern