257 research outputs found

    A theory of Careers in Hierarchical Internal Labor Markets

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    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

    Gene content evolution in the arthropods

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    Arthropods comprise the largest and most diverse phylum on Earth and play vital roles in nearly every ecosystem. Their diversity stems in part from variations on a conserved body plan, resulting from and recorded in adaptive changes in the genome. Dissection of the genomic record of sequence change enables broad questions regarding genome evolution to be addressed, even across hyper-diverse taxa within arthropods. Using 76 whole genome sequences representing 21 orders spanning more than 500 million years of arthropod evolution, we document changes in gene and protein domain content and provide temporal and phylogenetic context for interpreting these innovations. We identify many novel gene families that arose early in the evolution of arthropods and during the diversification of insects into modern orders. We reveal unexpected variation in patterns of DNA methylation across arthropods and examples of gene family and protein domain evolution coincident with the appearance of notable phenotypic and physiological adaptations such as flight, metamorphosis, sociality, and chemoperception. These analyses demonstrate how large-scale comparative genomics can provide broad new insights into the genotype to phenotype map and generate testable hypotheses about the evolution of animal diversity
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