Quitting and labor turnover : microeconomic evidence and macroeconomic consequences

Combining microeconomic evidence with macroeconomic theory, the authors present an integrated approach to wage and employment determination in an economy where firms pay above market"efficiency wages"to prevent trained workers from quitting. The model offers predictions about the behavior of formal employment, labor turnover, and segmentation in response to formal sector productivity shocks (including economic growth and tax reductions), changes in the desirability of self-employment (formal sector tax rates), and the cost of training a new worker. They use panel data from Mexican labor surveys to estimate the quit function derived fromthe model and the results support their view that transitions from formal salaried work to informal self-employment are quits rather than fires. (Quitting is positively related to the mean self-employment income and the probability of being rehired and negatively related to the mean formal salaried wage.) They then use the parameters estimated from the quit function to calibrate the model economy and simulate the impacts of economic shocks and policy innovations and find the impact on employment, turnover, and segmentation to be substantial.Environmental Economics&Policies,Public Health Promotion,Labor Policies,Economic Theory&Research,Labor Management and Relations,Health Monitoring&Evaluation,Banks&Banking Reform,Environmental Economics&Policies,Economic Theory&Research,Labor Management and Relations

Ab initio calculation of the Hoyle state

The Hoyle state plays a crucial role in the hydrogen burning of stars heavier than our sun and in the production of carbon and other elements necessary for life. This excited state of the carbon-12 nucleus was postulated by Hoyle [1] as a necessary ingredient for the fusion of three alpha particles to produce carbon at stellar temperatures. Although the Hoyle state was seen experimentally more than a half century ago [2,3], nuclear theorists have not yet uncovered the nature of this state from first principles. In this letter we report the first ab initio calculation of the low-lying states of carbon-12 using supercomputer lattice simulations and a theoretical framework known as effective field theory. In addition to the ground state and excited spin-2 state, we find a resonance at -85(3) MeV with all of the properties of the Hoyle state and in agreement with the experimentally observed energy. These lattice simulations provide insight into the structure of this unique state and new clues as to the amount of fine-tuning needed in nature for the production of carbon in stars.Comment: 4 pp, 3 eps figs, version accepted for publication in Physical Review Letter

Income Mobility and Welfare

This paper develops a framework for the quantitative analysis of individual income dynamics, mobility and welfare. Individual income is assumed to follow a stochastic process with two (unobserved) components, an i.i.d. component representing measurement error or transitory income shocks and an AR(1) component representing persistent changes in income. We use a tractable consumption-saving model with labor income risk and incomplete markets to relate income dynamics to consumption and welfare, and derive analytical expressions for income mobility and welfare as a function of the various parameters of the underlying income process. The empirical application of our framework using data on individual incomes from Mexico provides striking results. Much of measured income mobility is driven by measurement error or transitory income shocks and therefore (almost) welfare-neutral. A smaller part of measured income mobility is due to either welfare-reducing income risk or welfare-enhancing catching-up of lowincome individuals with high-income individuals, both of which have economically significant effects on social welfare. Decomposing mobility into its fundamental components is thus seen to be crucial from the standpoint of welfare evaluation

Finite-dimensional representation of the quadratic algebra of a generalized coagulation-decoagulation model

The steady-state of a generalized coagulation-decoagulation model on a one-dimensional lattice with reflecting boundaries is studied using a matrix-product approach. It is shown that the quadratic algebra of the model has a four-dimensional representation provided that some constraints on the microscopic reaction rates are fulfilled. The dynamics of a product shock measure with two shock fronts, generated by the Hamiltonian of this model, is also studied. It turns out that the shock fronts move on the lattice as two simple random walkers which repel each other provided that the same constraints on the microscopic reaction rates are satisfied.Comment: Minor revision

Study of the general mechanism of stress corrosion of aluminum alloys and development of techniques for its detection Quarterly report, 1 Dec. 1967 - 29 Feb. 1968

Stress corrosion of aluminum alloys and techniques for its detectio