A theory of Careers in Hierarchical Internal Labor Markets

The paper develops a model that explains a broad pattern of evidence on careers in multilevel organizations. It shows how job mobility inside firms depends on changes in the size of the organization. Promotion rates rise (fall) during a corporate expansion (contraction). Economic conditions therefore affect individual career mobility and earnings profiles. The model analyzes how the interaction between human capital accumulation and learning impacts on the assignment of workers to jobs at different levels of authority in the corporate hierarchy. The model makes predictions about the timing of the provision of formal training.career mobility, learning, sorting job assignment

Three-dimensional disordered conductors in a strong magnetic field: surface states and quantum Hall plateaus

We study localization in layered, three-dimensional conductors in strong magnetic fields. We demonstrate the existence of three phases - insulator, metal and quantized Hall conductor - in the two-dimensional parameter space obtained by varying the Fermi energy and the interlayer coupling strength. Transport in the quantized Hall conductor occurs via extended surface states. These surface states constitute a subsystem at a novel critical point, which we describe using a new, directed network model.Comment: 4 pages (PostScript) replaced due to compression error, slightly shortened version to appear in PR

The C-terminal extension of the beta 7 subunit and activator complexes stabilize nascent 20 S proteasomes and promote their maturation

The eukaryotic 20 S proteasome is formed by dimerization of two precursor complexes containing the maturation factor Ump1. beta 7/Pre4 is the only one of the 14 subunits forming the 20 S proteasome that is absent from these precursor complexes in Saccharomyces cerevisiae. Increased expression of Pre4 leads to a reduction in the level of precursor complex, indicating that Pre4 incorporation into these complexes is rate-limiting for their dimerization. When we purified these precursor complexes, we observed co-purification of Blm10, a large protein known to attach to the alpha ring surface of proteasomes. In contrast to single mutants lacking either Blm10 or the C-terminal extension of Pre4, a mutant lacking both grew extremely poorly, accumulated very high levels of precursor complexes, and was impaired in beta subunit maturation. The effect of blm10 Delta on proteasome biogenesis is modest, apparently because the 19 S regulatory particle is capable of substituting for Blm10, as long as precursor complex dimers are stabilized by the Pre4Cterminus. We found that a mutation (sen3/rpn2) affecting the Rpn2 subunit inhibits attachment of the 19 S activator to the 20 S particle or its precursors. Although the sen3 mutation alone had no apparent effect on precursor complex dimerization and active site maturation, the sen3 blm10 double mutant was impaired in these processes. Together these data demonstrate that Blm10 and the 19 S activator have a partially redundant function in stabilizing nascent 20 S proteasomes and in promoting their activation.info:eu-repo/semantics/publishedVersio

Appropriate spatial sampling of rainfall for flow simulation

The objective of this study is to find the appropriate number and location of raingauges for a river basin for flow simulation by using statistical analyses and hydrological modelling. First, a statistical method is used to identify the appropriate number of raingauges. Herein the effect of the number of raingauges on the cross-correlation coefficient between areally averaged rainfall and discharge is investigated. Second, a lumped HBV model is used to investigate the effect of the number of raingauges on hydrological modelling performance. The Qingjiang River basin with 26 raingauges in China is used for a case study. The results show that both cross-correlation coefficient and modelling performance increase hyperbolically, and level off after five raingauges (therefore identified to be the appropriate number of rain-gauges) for this basin. The geographical locations of raingauges which give the best and worst hydrological modelling performance are identified, which shows that there is a strong dependence on the local geographical and climatic patterns