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Biomedical subjects

D Beamish

Publications and source records attributed to D Beamish.

15 recordsLinked to original sources
PubMed2006

Speed-accuracy trade-off in planned arm movements with delayed feedback.

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 important new properties of the circuit emerge: a breakdown of Fitts' law when the movement time is small relative to the delay; and a positive Fitts' law Y-intercept. This breakdown of Fitts' law for tasks with small Index of Difficulty has been previously observed experimentally, and we suggest it may be attributed at least in part to delay effects in the nervous system elaborated by the model. Additionally, this gives a theoretical explanation for why positive Fitts' law Y-intercept should occur, and that it is related to the delay within the movement circuit.

Arm↗
PubMed1998

[Robert's story].

Explore the source record for details and available documents.

Adolescent↗
PubMed1981

Adverse responses to i.v. anaesthetics.

The adverse reactions to i.v. anaesthetics which occurred during a 3-yr period in one hospital were investigated. Sixteen reactions were reported; 13 of these occurred in a total of 7906 administrations of Althesin, two in 45 546 administrations of thiopentone and one in 630 administrations of methohexitone. The pathological process was identified in 10 patients. Most reactions were caused by activation of the alternate pathway for complement conversion.

Adolescent↗
PubMed1981

Allergic reaction to an amide local anaesthetic.

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 first report of allergy to a local anaesthetic drug which has been documented by concurrent immunological changes.

Aged↗
PubMed1980

Prolonged infusion of chlormethiazole in intensive care.

Chlormethiazole has proved useful for prolonged sedation in patients receiving artificial ventilation of the lungs during intensive care. In short-term infusions sedation and unconsciousness can be produced quickly and reversal is rapid on stopping the administration. After prolonged infusion, however, recovery is much slower because of accumulation of the drug. The pharmacokinetics of chlormethiazole in both short and prolonged infusions were studied in four patients. Following brief administrations the drug disappeared very quickly from the blood as a result of re-distribution and the patients wakened after a few minutes. Unconsciousness was associated with plasma concentrations in the range of 3--5 micrograms ml-1. After 48 h administration, recovery was much slower, the elimination half-life varying from 3.5 to 12.1 h.

Adolescent↗
PubMed1980

Delayed adverse responses to both methohexitone and Althesin.

A patient who reacted to both methohexitone and Althesin on separate occasions is described. On each occasion the reaction was delayed following anaesthesia. Underlying chronic infection had sensitised the patient's complement pathway, allowing it to be activated by two unrelated intravenous anaesthetic agents.

Abscess↗