Thermodynamics of Trapped Imbalanced Fermi Gases at Unitarity

We present a theory for the low-temperature properties of a resonantly interacting Fermi mixture in a trap, that goes beyond the local-density approximation. The theory corresponds essentially to a Landau-Ginzburg-like approach that includes self-energy effects to account for the strong interactions at unitarity. We show diagrammatically how these self-energy effects arise from fluctuations in the superfluid order parameter. Gradient terms of the order parameter are included to account for inhomogeneities. This approach incorporates the state-of-the-art knowledge of the homogeneous mixture with a population imbalance exactly and gives good agreement with the experimental density profiles of Shin et al. [Nature 451, 689 (2008)]. This allows us to calculate the universal surface tension of the interface between the equal-density superfluid and the partially polarized normal state of the mixture. We also discuss the possibility of a metastable state to explain the deformation of the superfluid core that is seen in the experiment of Partridge et al. [Science 311, 503 (2006)].Comment: 26 pages, 7 figures, contribution to Lecture Notes in Physics "BCS-BEC crossover and the Unitary Fermi Gas" edited by W. Zwerge

Psychological ownership and organizational optimism amid China's corporate transformation: Effects of an employee ownership scheme and a management-dominated board

Ownership reform was introduced to Chinese state-owned enterprises in the early 1990s, to allow employees to own a share of their enterprises and to bring changes to the underlying structure of governance. However, effectiveness of this reform has yet to be ascertained. This study examines the effects of the new employee stock ownership scheme and board compositions on the attitudes employees hold towards their jobs and organizations, as well as their perceptions of ownership. We developed a theoretical model on how participation in a stock ownership scheme (an employee's characteristic) and the composition of the board of governance (a firm characteristic) may be linked to job satisfaction and, in turn, to outcome variables such as psychological ownership and organizational optimism. This model was tested on 510 employees randomly sampled from ten stock-holding enterprises in urban Shanghai. Results indicate that participation in a stock ownership scheme has a positive effect on attitudes towards ownership, but that a board dominated by senior managers leads to gloomy perception of a firm's future. These effects were partially mediated by the satisfaction that employees felt in their jobs. The implications of these findings for management practices in China are discussed.link_to_subscribed_fulltex