Signalling plasticity and energy saving in a tropical bushcricket

Males of the tropical bushcricket Mecopoda elongata synchronize their acoustic advertisement signals (chirps) in interactions with other males. However, synchrony is not perfect and distinct leader and follower roles are often maintained. In entrainment experiments in which conspecific signals were presented at various rates, chirps displayed as follower showed notable signal plasticity. Follower chirps were shortened by reducing the number and duration of syllables, especially those of low and medium amplitude. The degree of shortening depended on the time delay between leader and follower signals and the sound level of the entraining stimulus. The same signal plasticity was evident in male duets, with the effect that the last syllables of highest amplitude overlapped more strongly. Respiratory measurements showed that solo singing males producing higher chirp rates suffered from higher metabolic costs compared to males singing at lower rates. In contrast, respiratory rate was rather constant during a synchronous entrainment to a conspecific signal repeated at various rates. This allowed males to maintain a steady duty cycle, associated with a constant metabolic rate. Results are discussed with respect to the preference for leader signals in females and the possible benefits males may gain by overlapping their follower signals in a chorus

Foreign presence, technical efficiency and firm survival in Greece: a simultaneous equation model with latent variables approach

The aim of the paper is to explain the role that technical efficiency and foreign spillover effects have on firm survival. Panel data from Greek manufacturing industry (3142 firms) in 1997-2003 are used. Technical efficiency is estimated through a CES translog production function. A hazard function is then used (corresponding to the Exponential and Weibull distributions as well as the Cox model) to estimate survival probabilities. While foreign spillovers exercise a positive impact on hazard, foreign firms do not have any distinctive survival advantage compared to their domestic rivals. On the contrary, technical efficiency affects hazard in a negative way, improving survival expectations

Incorporating efficiency in hospital-capacity planning in Germany

Hospital capacity planning, Hospital efficiency, Data envelopment analysis, C61, H51, I18,