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

Conservative management of significant epidural haematomas in children

Objective: A significant epidural haematoma (EDH) is generally treated by craniotomy and evacuation. This is a report of conservative management following an EDH on computerized tomography (CT) in a paediatric population. The authors examined whether conservative treatment of radiologically significant EDH is a successful and safe therapeutic option. Methods: Retrospective data were collected from charts of patients with conservatively treated EDH in the Department of Surgery of the University Children's Hospital Zurich between September 1993 and January 2004. Included were patients without focal neurological deficits, with a Glasgow Coma Scale (GCS) of 15 and an initial CT demonstrating an EDH with a minimal thickness of 1cm. Mild clinical symptoms of raised intracranial pressure such as headache, nausea or vomiting were treated symptomatically. Follow-up included a standardized interview, a neuropaediatric examination and CT. Results: Thirteen children with EDH had successful conservative management. Only one 12-year-old female patient with a delayed diagnosed frontal EDH required surgical intervention 24h after admission and 5 days after the accident. Clinical follow-up showed patients without neurological deficits, a Glasgow Outcome Scale of 5 and no post-traumatic sequelae over an average of 4 4/12 years (range 4 months to 10 4/12 years). Follow-up CT showed complete resolution of the EDH within 2 to 3 months. Conclusions: Our results demonstrate that significant EDH can be treated non-operatively in neurologically normal children. We recommend that such treatment be performed in specialised paediatric centres under adequate neurological observation since prompt emergency operation in case of neurological deterioration should be provide

Die psychosoziale/-sexuelle Entwicklung von Knaben mit einer Hypospadie

Zusammenfassung: Knaben mit einer Hypospadie sind spezifischen psychischen Belastungen im Zusammenhang mit dem chirurgischen Eingriff im Genitalbereich und einem kosmetisch und/oder funktionell beeinträchtigten Penis ausgesetzt. Während in den letzten Jahrzehnten intensive Anstrengungen zur Verbesserung der Operationstechniken unternommen worden sind, wurde die psychosoziale und psychosexuelle Entwicklung von Kindern und Jugendlichen nach Hypospadiekorrektur erst selten untersucht. Die Resultate der wenigen Studien sind insgesamt sehr widersprüchlich. Sie weisen aber auch deutlich daraufhin, dass die betroffenen Knaben unter spezifischen Problemen wie dem andersartigen Aussehen ihres Penis leiden. Das Angebot von medizinischen Verlaufskontrollen und psychosozialer Beratung muss ihnen deshalb bis ins junge Erwachsenenalter zur Verfügung gestellt werden. Für die zukünftige Forschung gilt es, in methodisch fundierten Studien Lebensqualität und Entwicklung der Knaben systematisch zu untersuchen. Dabei müssen insbesondere psychosoziale Risikofaktoren identifiziert werde

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

Fractional smoothness and applications in finance

This overview article concerns the notion of fractional smoothness of random variables of the form $g(X_T)$, where $X=(X_t)_{t\in [0,T]}$ is a certain diffusion process. We review the connection to the real interpolation theory, give examples and applications of this concept. The applications in stochastic finance mainly concern the analysis of discrete time hedging errors. We close the review by indicating some further developments.Comment: Chapter of AMAMEF book. 20 pages

Medial clavicular epiphysiolysis in children: the so-called sterno-clavicular dislocation

We retrospectively reviewed six pediatric cases of medial clavicular injury, i.e., epiphyseal separation (Salter/Harris type I or II injury), diagnosed between 1993 and 1997. The clavicular metaphysis was displaced posteriorly in three cases and anteriorly in three. On conventional radiographic views the diagnosis was initially missed in two of three retrosternal dislocations. A special X-ray projection (described by Heinig) or computed tomography (CT) permitted correct diagnosis. Anterior dislocations were immediately and correctly diagnosed. Closed reduction successfully treated retrosternal displacement in two of the three patients. The third patient needed open reduction and internal fixation. Open reduction and internal fixation had to be performed in all three patients with anterior displacement. Follow-up assessment showed perfect functional results in all cases. Direct visualization during open reduction, which was necessary in four of six cases, yielded clear evidence that the so-called sternoclavicular dislocation in children and young adults is, in fact, a fracture of the medial growth plate with posterior or anterior displacement of the metaphysi

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

Submicron silicon powder production in an aerosol reactor

Powder synthesis by thermally induced vapor phase reactions is described. The powder generated by this technique consists of spherical, nonagglomerated particles of high purity. The particles are uniform in size, in the 0.1–0.2 µm size range. Most of the particles are crystalline spheres. A small fraction of the spheres are amorphous. Chain agglomerates account for less than 1% of the spherules

Is there an ideal age for hypospadias repair? A pilot study

OBJECTIVE: To assess whether repairing hypospadias before or after 18 months affects psychological adjustment, health-related quality of life (HRQoL) and surgical outcome. PATIENTS AND METHODS: Seventy-seven boys aged 6-17 years were assigned to one of two groups, according to whether they had a hypospadias repair before or after the age of 18 months. The surgical outcome was assessed using the pediatric penile perception score by non-involved urologists. A psychologist interviewed the patients to assess HRQoL and gender-role behavior. The child's psychological adjustment was assessed with a questionnaire for parents. RESULTS: The surgical outcome and complication rate were not significantly different between groups. A covariance analysis of HRQoL, gender-role behavior and psychological adjustment as a function of age at the last operation with current age as covariant was performed, but differences did not reach significance. CONCLUSION: This study does not provide evidence to support recommendations concerning the ideal age for hypospadias repair. In the absence of evidence of a benefit of early surgery, anesthesia-related risk factors must be considered when operating in very early infancy. Large, prospective studies, measuring surgical and psychological outcome with similar instruments to those presented may reveal whether there is a true ideal age for hypospadias surgery