Monocular discrimination of rigidly and nonrigidly moving objects

Wemeasured thresholds for the monocular discrimination of rigidly and nonrigidly moving objects defined by motion parallax. The retinal projections of rigidly moving objects are subject to certain constraints. By applying smooth 2-D transformations to the projections of rigidly moving objects, we created stimuli in which these constraints were affected. Thresholds for (generic) nonrigid transformations that in theory can be detected from rigid ones by processing pairs of views depended not only on the extent to which the rigidity constraints were affected, but also on the structure and the movement of the simulated object. Nonrigid transformations under which every three successive views had a rigid interpretation were not discriminable from rigid transformations, except in cases where the distortions were very large. Under the rigidity assumption, this would mean that a large class of nonrigidly moving objects is erroneously perceived as rigidly moving.     

Relation between EMG activation patterns and kinematic properties of aimed arm movements

Aimed flexion movements of the arm of different amplitude and duration were studied. Velocity and acceleration traces of movements with equal duration but different amplitude were equal, apart from a scaling factor (ratio between movement amplitudes). After appropriate scaling, EMG activity of the first agonist burst for these movements superimposed. This was not true for EMG activity in the antagonist muscle. For movements with equal amplitude, but different duration, the time to peak acceleration was constant for all MT'. Except for this fact, traces of acceleration, velocity, and agonist activity following the time of peak acceleration were about equal after appropriate scaling in time and amplitude. The integral of EMG activity in the first agonist burst increased linearly with peak velocity. For the antagonist burst, the integrated EMG activity increased more than proportionally. During movements made as fast as possible, subjects used a different strategy by varying the duration of the accelerating phase for movements of different amplitude. Movement amplitude was achieved by adjusting the duration of the agonist burst and the onset time for the antagonist muscle. Amplitude of the antagonist burst was constant within a narrow range for movements of different amplitude. These results did not change when the inertial mass was doubled by loading the arm with an additional mass.     

Knowledge management in strategic planning: The case of the dutch fourth report

This article examines the management and use of knowledge in a relatively complex planning and policy process, i.e., the preparation and implementation of the Fourth Report on Physical Planning in the Netherlands. Attention is given to the organization of this process; the manner in which research, policy design and plan negotiation were intertwined in the various phases of the process; and the solutions developed for the problem of obtaining sufficient knowledge without losing the impetus essential to policy-making. General conclusions are derived especially concerning the interrelationship between policy-making and the accretion and depletion of knowledge stocks. While his earlier publications were primarily concerned with the application of demographic research in spatial policy, he has more recently shifted his attention to knowledge utilization problems in general.     

CAMERA: A system for fast and reliable acquisition of multiple ethological records

CAMERA is a system for collecting and editing ethological data. The hardware and software enable easy coding of complex behavioral interactions from video recordings. It is especially designed to improve accuracy, reliability, and training standards in coding behavior. The system also supports several basic analyses of collected data. CAMERA operates with both North American and European video signals.     

Politics on the move: The democratic control of the design of sustainable technologies

This article examines how “design rationality” could help remediate the controversy over environmental degradation. Drawing on the case of designing sustainable forms of traffic management, it argues that this will only be effective to a limited degree. “Policy conversation” does indeed take place but within a coalition of actions that pushes a particular set of solutions. This facilitates due procedure but erodes political legitimacy, thus potentially reproducing an intractable controversy. The article suggests a five-phase model of democratic control as an alternative. He primarily works in the field of sociology of technology and environment. He is presently involved in a research project on the social redefinition of mobility, analyzing the translation of sustainable development into new institutional arrangements.     

Sahlqvist's theorem for boolean algebras with operators with an application to cylindric algebras

For an arbitrary similarity type of Boolean Algebras with Operators we define a class ofSahlqvist identities. Sahlqvist identities have two important properties. First, a Sahlqvist identity is valid in a complex algebra if and only if the underlying relational atom structure satisfies a first-order condition which can be effectively read off from the syntactic form of the identity. Second, and as a consequence of the first property, Sahlqvist identities arecanonical, that is, their validity is preserved under taking canonical embedding algebras. Taken together, these properties imply that results about a Sahlqvist variety V van be obtained by reasoning in the elementary class of canonical structures of algebras in V.We give an example of this strategy in the variety of Cylindric Algebras: we show that an important identity calledHenkin's equation is equivalent to a simpler identity that uses only one variable. We give a conceptually simple proof by showing that the first-order correspondents of these two equations are equivalent over the class of cylindric atom structures.Presented byIstván Németi     

Constrained maximization reconsidered — An elaboration and critique of Gauthier's modelling of rational cooperation in a single prisoner's dilemma

Gauthier's argument for constrained maximization, presented inMorals by Agreement, is perfected by taking into account the possibility of accidental exploitation and discussing the limitations on the values of the parameters which measure the translucency of the actors. Gauthier's argument is nevertheless shown to be defective concerning the rationality of constrained maximization as a strategic choice. It can be argued that it applies only to a single actor entering a population of individuals who are themselves not rational actors but simple rule-followers. A proper analysis of the strategic choice situation involving two rational actors who confront each other shows that constrained maximization as the choice of both actors can only result under very demanding assumptions.     

A low-cost video game applied for training of upper extremity function in children with cerebral palsy: a pilot study

The aim of the present study was to determine the user satisfaction of the EyeToy for the training of the upper limb in children with cerebral palsy (CP). User satisfaction was measured in 12 children with CP, using a postexperience questionnaire, primarily based on a presence questionnaire. In general, children with CP were satisfied with and motivated by the EyeToy training. In addition, a first evaluation study was performed to determine the effect of this training method on the upper limb function. Ten children with CP were randomly assigned to the intervention (mean age 11 years, 9 months; SD 2,3) and the control group (mean age 12 years, 3 months; SD 3,2). After a treatment period of 6 weeks, the intervention group completed a user satisfaction questionnaire. Functional outcome was measured using the Melbourne Assessment scores. Percentage scores of the Melbourne Assessment of 7 of the 10 children were the same or changed only 1% to 2% from baseline to followup. However, in the experimental group, two children improved more, 9% and 13% respectively. In conclusion, it can be said that the EyeToy is a motivational training tool for the training of children with CP and has the potential to improve upper extremity function.