The rate of change in resting metabolic rate (RMR) as a result of a temperature increase of 10 °C is termed the temperature coefficient (Q10), which is often used to predict how an organism's total MR will change with temperature. However, this method neglects a potentially key component of MR; changes in activity level (and thus activity MR; AMR) with temperature may significantly alter the relationship between MR and temperature. The present study seeks to describe how thermal effects on total MR estimated from RMR-temperature measurements can be misleading when the contribution of activity to total MR is neglected. A simple conceptual framework illustrates that since the relationship between activity levels and temperature can be different to the relationship between RMR and temperature, a consistent relationship between RMR and total MR cannot be assumed. Thus the thermal effect on total MR can be considerably different to the thermal effect on RMR. Simultaneously measured MR and activity from three ectotherm species with differing behavioural and physiological ecologies were used to empirically examine how changes in temperature drive changes in RMR, activity level, AMR and the Q10 of MR. These species exhibited varied activity- and MR-temperature relationships, underlining the difficulty in predicting thermal influences on activity levels and total MR. These data support a model showing that thermal effects on total MR will deviate from predictions based solely on RMR; this deviation will depend upon the difference in Q10 between AMR and RMR, and the relative contribution of AMR to total MR. To develop mechanistic, predictive models for species' metabolic responses to temperature changes, empirical information about the relationships between activity levels, MR and temperature, such as reported here, is required. This will supersede predictions based on RMR alone.

In the conventional Faraday generator a conducting disk rotates in an axial magnetic field. If the disk is replaced by a cylindrical permanent magnet that supplies its own magnetic field, the effect is identical. It follows that any moving magnet generates an induced electromotive force due to the presence of its own field: this generalization leads to an apparent paradox in the case of translational motion for it implies the possibility that an observer in an inertial frame could measure his absolute velocity.

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We present preliminary results from continuous-wave experiments made on two single crystals of bismuth. The object of the experiments was the examination of the initial deviations from diffusive propagation with increasing thermal signal frequency. The thermal conductivity of bismuth is phonon-dominated at low temperatures and has a peak of the type found in good dielectric crystals. However, the observed initial deviations were not in quantitative agreement with results obtained by applying a simple theory of second sound in dielectric crystals.

A three-phase motor is described which has one or more loops of superconductor for its rotor and uses superconducting field coils. The theory of the motor is outlined, including the case when flux is frozen into the rotor. The predictions of the theory are compared with the experimentally observed torque produced by the motor.