Dan Beamish

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An intrinsic property of human motor behaviour is a trade-off between speed and accuracy. This is classically described by Fitts' law, a model derived by assuming the human body has a limited capacity to transmit information in organizing motor behaviour. Here, we propose an alternative foundation, based on the neurodynamics of the motor circuit, wherein(More)
An intrinsic property of human motor behavior is a trade-off between speed and accuracy. This is classically described by Fitts' law, a model derived by assuming that the human body has a limited capacity to transmit information in organizing motor behavior. However, Fitts' law can also be realized as an emergent property of movements generated by delayed(More)
The Noggin 250 MHz GPR being used in combination with the Dual EM ground conductivity meter (long yellow boom) on the Holme Pierrepont sand and gravel deposit. The London Information Office maintains a reference collection of BGS publications including maps for consultation. The Survey publishes an annual catalogue of its maps and other publications; this(More)
The Vector Integration To Endpoint (VITE) circuit describes a real time neural network model which simulates behavioral and neurobiological properties of planned arm movements by the interaction of two populations of neurons. This model is generalized to include delay between the interacting populations, which is found to have a detrimental effect on(More)
We discuss natural limitations on motor performance caused by the time delay required for feedback signals to propagate within the human body or mechanical control systems. By considering a very simple delayed linear servomechanism model, we show there exists a best possible speed-accuracy trade-off similar to Fitts' law that cannot be exceeded when delay(More)
The Vector Integration to Endpoint (VITE) circuit describes a real-time neural network model simulating behavioral and neurobiological properties of planned arm and hand movements by the interaction of two populations of neurons. We analyze the speed-accuracy trade-off generated by this circuit, generalized to include delayed feedback. With delay, two(More)
The effect of [bis-(4-methyl-1-homopiperazinylthiocarbonyl)-disulfide] (FLA-63) (40 mg/kg, i.p.) on acquisition and retention in four different avoidance tasks was evaluated in mice. In all tasks animals were submitted to a training session on one day and to a retest session 24 h later. The drug or its vehicle were given either 2 h prior to training and/or(More)
A 67-yr-old female patient gave a history of allergy to lignocaine. When she was challenge-tested with the intradermal injection of 0.5% bupivacaine 0.2ml she had a systemic reaction. This reaction was accompanied by a decrease in the concentration of complement C4 in the plasma, which indicated that the reaction was immunologically-mediated. This is the(More)
Quasi-Spherical harmonics, Y m ℓ (θ, φ) are derived and presented for half-odd-integer values of ℓ and m. The form of the φ factor is identical to that in the case of integer ℓ and m: exp (imφ). However, the domain of these functions in the half-odd-integer case is 0≤φ<4π rather than the domain 0≤φ<2π in the case of integer ℓ and m (the true spherical(More)