SUMMARY1. Respiratory responses to sustained isometric contractions of a small mass of muscle (the finger flexors) during handgripping, and of a larger mass of muscle (the quadriceps) during extension of the leg at the knee, have been studied in man.2. For both masses of muscle the increases of ventilation and of oxygen consumption were greater for contractions at 40 % maximum voluntary contraction (MVC) than for contractions at 20 % MVC.3. The increase of ventilation was not related to the mass of muscle involved. 4. At 20% MVC oxygen consumption during contraction of the quadriceps was greater than that during handgripping. At 40 % MVC the oxygen consumptions were similar. The oxygen debts following both handgrip and knee extensor contractions at 20 % MVC were negligible. Following 40 % MVC contractions of the quadriceps a significant oxygen debt was recorded but no debt was apparent following 40 % MVC contractions of the finger flexors.5. The increases of ventilation during isometric exercise were generally inappro-

We report the contrast-enhanced magnetic resonance imaging (MRIg) findings from a series of 1139 patients who underwent screening to exclude a diagnosis of vestibular schwannoma. An acoustico-facial nerve bundle tumour was found in 3.1 per cent of patients imaged and vestibular schwannoma incidence is estimated at 1.4 per 100,000 population per annum. MRIg showed an abnormality in 14 per cent of patients; about one third of the findings may have accounted for the presenting symptom(s). A small number of patients had unexpected pathology revealed that required onward referral for further active management.

As a first step towards an acoustic localisation device for coronary stenosis to provide a non-invasive means of diagnosing arterial disease, measurements are reported for an agar-based tissue mimicking material (TMM) of the shear wave propagation velocity, attenuation and viscoelastic constants, together with one dimensional quasi-static elastic moduli and Poisson's ratio. Phase velocity and attenuation coefficients, determined by generating and detecting shear waves piezo-electrically in the range 300 Hz-2 kHz, were 3.2-7.5 ms(-1) and 320 dBm(-1). Quasi-static Young's modulus, shear modulus and Poisson's ratio, obtained by compressive or shear loading of cylindrical specimens were 150-160 kPa; 54-56 kPa and 0.37-0.44. The dynamic Young's and shear moduli, derived from fitting viscoelastic internal variables by an iterative statistical inverse solver to freely oscillating specimens were 230 and 33 kPa and the corresponding relaxation times, 0.046 and 0.036 s. The results were self-consistent, repeatable and provide baseline data required for the computational modelling of wave propagation in a phantom.

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