Evolving collective behavior in an artificial ecology

Collective behavior refers to coordinated group motion, common to many animals. The dynamics of a group can be seen as a distributed model, each “animal” applying the same rule set. This study investigates the use of evolved sensory controllers to produce schooling behavior. A set of artificial creatures “live” in an artificial world with hazards and food. Each creature has a simple artificial neural network brain that controls movement in different situations. A chromosome encodes the network structure and weights, which may be combined using artificial evolution with another chromosome, if a creature should choose to mate. Prey and predators coevolve without an explicit fitness function for schooling to produce sophisticated, nondeterministic, behavior. The work highlights the role of species’ physiology in understanding behavior and the role of the environment in encouraging the development of sensory systems

Measuring Chess Experts' Single-Use Sequence Knowledge: An Archival Study of Departure from ‘Theoretical’ Openings

The respective roles of knowledge and search have received considerable attention in the literature on expertise. However, most of the evidence on knowledge has been indirect – e.g., by inferring the presence of chunks in long-term memory from performance in memory recall tasks. Here we provide direct estimates of the amount of monochrestic (single use) and rote knowledge held by chess players of varying skill levels. From a large chess database, we analyzed 76,562 games played in 2008 by individuals ranging from Class B players (average players) to Masters to measure the extent to which players deviate from previously known initial sequences of moves (“openings”). Substantial differences were found in the number of moves known by players of different skill levels, with more expert players knowing more moves. Combined with assumptions independently made about the branching factor in master games, we estimate that masters have memorized about 100,000 opening moves. Our results support the hypothesis that monochrestic knowledge is essential for reaching high levels of expertise in chess. They provide a direct, quantitative estimate of the number of opening moves that players have to know to reach master level

Evolving process-based models from psychological datausing genetic programming

The development of computational models to provide explanations of psychological data can be achieved using semi-automated search techniques, such as genetic programming. One challenge with these techniques is to control the type of model that is evolved to be cognitively plausible – a typical problem is that of “bloating”, where continued evolution generates models of increasing size without improving overall fitness. In this paper we describe a system for representing psychological data, a class of process-based models, and algorithms for evolving models. We apply this system to the delayed match-to-sample task. We show how the challenge of bloating may be addressed by extending the fitness function to include measures of cognitive performance

Assessing the potential of autonomous submarine gliders for ecosystem monitoring across multiple trophic levels (plankton to cetaceans) and pollutants in shallow shelf seas

A combination of scientific, economic, technological and policy drivers is behind a recent upsurge in the use of marine autonomous systems (and accompanying miniaturized sensors) for environmental mapping and monitoring. Increased spatial–temporal resolution and coverage of data, at reduced cost, is particularly vital for effective spatial management of highly dynamic and heterogeneous shelf environments. This proof-of-concept study involves integration of a novel combination of sensors onto buoyancy-driven submarine gliders, in order to assess their suitability for ecosystem monitoring in shelf waters at a variety of trophic levels. Two shallow-water Slocum gliders were equipped with CTD and fluorometer to measure physical properties and chlorophyll, respectively. One glider was also equipped with a single-frequency echosounder to collect information on zooplankton and fish distribution. The other glider carried a Passive Acoustic Monitoring system to detect and record cetacean vocalizations, and a passive sampler to detect chemical contaminants in the water column. The two gliders were deployed together off southwest UK in autumn 2013, and targeted a known tidal-mixing front west of the Isles of Scilly. The gliders’ mission took about 40 days, with each glider travelling distances of >1000 km and undertaking >2500 dives to depths of up to 100 m. Controlling glider flight and alignment of the two glider trajectories proved to be particularly challenging due to strong tidal flows. However, the gliders continued to collect data in poor weather when an accompanying research vessel was unable to operate. In addition, all glider sensors generated useful data, with particularly interesting initial results relating to subsurface chlorophyll maxima and numerous fish/cetacean detections within the water column. The broader implications of this study for marine ecosystem monitoring with submarine gliders are discussed

2,3-Bis[(2-methyl­phen­oxy)meth­yl]buta-1,3-diene

The mol­ecule of the title compound, C20H22O2, a symmetrically 2-methyl­phenol-substituted divinyl analog, exhibits crystallographically imposed C 2 symmetry. The mol­ecular structure is essentially planar. The structure is stabilized by a short inter­molecular C—H⋯O contact. Cooperative C—H⋯π inter­actions generate an infinite one-dimensional chain of mol­ecules along the a axis

HIGH PERFORMANCE LIQUID CHROMATOGRAPHY QUANTIFICATION OF OLEANOLIC ACID IN LAUNAEA TARAXACIFOLIA AND LARVICIDAL ACTIVITY AGAINST ANOPHELES GAMBIAE

Objective: One of the measures used to prevent malaria is the management of breeding sites. For preventive and ecologically profitable control, the use of bio-larvicides made from active plant extracts would be an asset for the control of malaria vectors, in particular Anopheles gambiae. Advances in pharmacognosy have revealed the benefits of several phytochemicals with very rich and varied therapeutic effects. Among the latter, oleanolic acid (OA) is quite remarkable because of its various and multiple properties, much of which is demonstrated with the leaves of Launaea taraxacifolia. Methods: After a liquid-liquid fractionation with different organic solvents of the hydro-methanolic extract of Launaea taraxacifolia, we obtained three fractions named Fhex (hexane fraction), FDCM (dichloromethane fraction) and FHM (hydro-methanolic fraction) which were tested on 3rd instar Anopheles gambiae larvae. Results: Fhex proved to be the most active with LC50 of 120.11 ppm and 69.50 ppm respectively in 24 and 48 hours of contact. We then developed a new method of Ultra-Violet High Performance Liquid Chromatography (HPLC / UV) method and determined the quantity of oleanolic acid in the Fhex and FDCM fractions to be respectively 0.46% and 0.23% . Conclusion: Launaea taraxacifolia has a larvicidal potential due to the presence of oleanolic acid whose inhibitory effect against Anopheles gambiae larvae

Herbert Simon's decision-making approach: Investigation of cognitive processes in experts

This is a post print version of the article. The official published can be obtained from the links below - PsycINFO Database Record (c) 2010 APA, all rights reserved.Herbert Simon's research endeavor aimed to understand the processes that participate in human decision making. However, despite his effort to investigate this question, his work did not have the impact in the “decision making” community that it had in other fields. His rejection of the assumption of perfect rationality, made in mainstream economics, led him to develop the concept of bounded rationality. Simon's approach also emphasized the limitations of the cognitive system, the change of processes due to expertise, and the direct empirical study of cognitive processes involved in decision making. In this article, we argue that his subsequent research program in problem solving and expertise offered critical tools for studying decision-making processes that took into account his original notion of bounded rationality. Unfortunately, these tools were ignored by the main research paradigms in decision making, such as Tversky and Kahneman's biased rationality approach (also known as the heuristics and biases approach) and the ecological approach advanced by Gigerenzer and others. We make a proposal of how to integrate Simon's approach with the main current approaches to decision making. We argue that this would lead to better models of decision making that are more generalizable, have higher ecological validity, include specification of cognitive processes, and provide a better understanding of the interaction between the characteristics of the cognitive system and the contingencies of the environment

Spring-neap tidal and circadian variability in the distribution of two groups of Pseudo-nitzschia species in an upwelling influenced estuary

High-resolution physical and biological measurements were carried out in the Ría de Pontevedra (NW Spain) in late spring during the ‘HABIT Pontevedra 2007’ survey, which utilized high vertical resolution instruments. Cell maxima of P. delicatissima (6 x 105 cells L-1) and P. seriata (2 x 106 cells L-1) groups were observed during the first half of the cruise during downwelling and a significant decrease in cell numbers occurred during subsequent upwelling conditions. The effect of tidal (both semidiurnal and spring-neap) and event driven (upwelling-downwelling cycle) variability were evident. The observed sequence of events suggests that Pseudo-nitzschia populations were advected from the shelf. The circadian variability was regulated by tidal forcing and Pseudo-nitzschia spp. maxima were observed at low tide. From results presented here we conclude that the magnitude of spring-neap tidal and circadian variability has to be considered when designing and implementing harmful algal bloom monitoring programmesEn prens