Labor market dynamics when effort depends on wage growth comparisons

We present an efficiency wage model in which workers'' effort depends on the level and on the growth rate of their wage relative to an alternative wage. Using data for four countries (US, UK, FR, GY), the implications of the model are examined and are found to be in accordance with the information in the non-stationary data. The restrictions implied by the model dynamics are not rejected by the data. Moreover the structural parameters are found to be constant through time, indicating that, although very simple, the model is likely to be robust to the Lucas critique. One interesting result is that the workers'' effort depends less on relative wages growth and more on relative wage levels in the US than in the three European countries analyzed.mathematical economics and econometrics ;

Two of the most common crustacean zooplankton Meganyctiphanes norvegica and Calanus spp. produce sounds within the hearing range of their fish predators

Sound is an effective channel for the transfer of information underwater. While it is known that fish and whales can use sound for communication, and as a cue to localise predators and prey, much less is known about sound production in invertebrates. Here we describe sounds produced by two of the most common marine crustacean zooplankton in the Northern hemisphere: Northern krill (Meganyctiphanes norvegica) and copepods (Calanus spp.). The recorded sounds were taxon-specific and within the hearing range of common planktivorous fish. We recorded similar sounds in the laboratory and in the field. In krill, the sound co-occurred with a tail flip, and the amplitude of the sound was correlated to the displacement distance of the animal, indicating a potential sound producing mechanism. Our findings highlight the possibility that zooplankton sounds could be used as a cue for their predators and for intraspecific communication.publishedVersio

Sound production in male and female corkwing wrasses and its relation to visual behaviour

In fish, social interactions are commonly accompanied by acoustic signalling. Males have been found to produce sounds in a large range of species, but female sounds have received considerably less attention. But even in males, there remain significant taxonomical gaps, e.g. in one of the largest fish families, the wrasses. Here, we investigate sound production in territorial males and females of the corkwing wrasse in a field study in Norway. We complemented an in-depth analysis of the visual and acoustic behavioural repertoire of territorial males by descriptions of female behaviours. Males as well as females produced sounds in courtship and agonistic contexts. We recorded four types of sounds and found significant differences between male and female sound properties. We hereby provide one of the first descriptions of sound production in wrasses and, to our knowledge, the first one to also investigate female sound production. Our study shows that wrasses are an underappreciated family when it comes to sound production. With a repertoire of four different calls, corkwing wrasses are remarkably versatile among fishes. Our results highlight the potential and importance of future research about sound communication in neglected taxa, and in both sexes.publishedVersio

Labor market dynamics when effort depends on wage growth comparisons

We present an efficiency wage model in which workers' effort depends on the level and on the growth rate of their wage relative to an alternative wage. Using data for four countries (US, UK, FR, GY), the implications of the model are examined and are found to be in accordance with the information in the non-stationary data. The restrictions implied by the model dynamics are not rejected by the data. Moreover the structural parameters are found to be constant through time, indicating that, although very simple, the model is likely to be robust to the Lucas critique. One interesting result is that the workers' effort depends less on relative wages growth and more on relative wage levels in the US than in the three European countries analyzed.efficiency wages; effort function; cointegration; GMM