Regional and occupational disparities in the wages of young blue- and white-collar workers

According to human capital theory the wages of people, who invest a comparable amount of time and money into an education should be also comparable. Therefore, the wages of work-ers who passed a three-year occupational education in the German so-called “dual system” represent a test of the theory. The “dual system” is a specific form of education in which ap-prentices are trained in an employing firm and in school. Descriptive analyses show that average wages between different occupations only one year after finishing the education differ by about 100 percent. In the past multivariate analyses were not available. In the paper a cross-classified multilevel model with fixed effects is used to identify specific effects of occupations and regions and to control for the heterogeneity of individual workers. The data base is the IAB Employment Sample which is a one percent sample of total employment. On the basis of this data the necessary differentiation for about 100 occupations and 327 regions is possible. In Germany occupational structures in the labour market are more important than in other countries. In the paper a comparison to the structure of regional disparities is given. Several theoretical hypotheses are tested to explain the differences.

Phase diagram of microcavity exciton-polariton condensates

In this work, we study the exciton-polariton condensate phase transition in a microcavity matter-light system in which electron-hole Coulomb interaction and matter-light coupling effects are treated on an equal footing. In the framework of the unrestricted Hartree-Fock approximation applying the two-dimensional exciton-polariton model, we derive the self-consistent equations determining simultaneously the excitonic and the photonic condenstate order parameters. In the thermal equilibrium limit, we find a condensed state of the exciton-polariton systems and phase diagrams are then constructed. At a given low temperature, the condensate by its nature shows a crossover from an excitonic to a polaritonic and finally photonic condensed state as the excitation density increases at large detuning. Without the detuning, the excitonic condensed state disappears whereas the polaritonic or photonic phases dominate. The crossover is also found by lowering the Coulomb interaction at a finite matter-light coupling. Lowering the Coulomb interaction or increasing the temperature, the excitonic Mott transition occurs, at which the exciton-polariton condensates dissociate to free electron-hole/photon. Depending on temperature and excitation density, the phase transition of the exciton-polariton condensates is also addressed in signatures of photoluminescence mapping to the photonic momentum distribution.Comment: 7 pages, 6 figure