16,300 research outputs found

    Calculation of Hydrogenic Bethe Logarithms for Rydberg States

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    We describe the calculation of hydrogenic (one-loop) Bethe logarithms for all states with principal quantum numbers n <= 200. While, in principle, the calculation of the Bethe logarithm is a rather easy computational problem involving only the nonrelativistic (Schroedinger) theory of the hydrogen atom, certain calculational difficulties affect highly excited states, and in particular states for which the principal quantum number is much larger than the orbital angular momentum quantum number. Two evaluation methods are contrasted. One of these is based on the calculation of the principal value of a specific integral over a virtual photon energy. The other method relies directly on the spectral representation of the Schroedinger-Coulomb propagator. Selected numerical results are presented. The full set of values is available at quant-ph/0504002.Comment: 10 pages, RevTe

    Is Job Enrichment Really Enriching?

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    This study uses a survey of Canadian workers with rich, matched data on job characteristics to examine whether “enriched” job design, with features like quality circles, feedback, suggestion programs, and task teams, affects job satisfaction. We identify two competing hypotheses on the relationship between enriched jobs and job satisfaction. The “motivation hypothesis,” implies that enrichment will generally increase satisfaction and the “intensification hypothesis,” implies that enrichment may decrease satisfaction by increasing the intensity and scope of work. Our results show that several forms of enrichment, specifically suggestion programs, information sharing, task teams, quality circles and training, raise satisfaction. Therefore we argue that the data support the motivation hypothesis. Partitioning the data by education level or union membership further supports this conclusion, while a direct test of the intensification hypothesis does not support the competing hypothesis.Job Satisfaction; Job Enrichment; Human Resource Practices

    Fundamental constants and tests of theory in Rydberg states of one-electron ions

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    The nature of the theory of circular Rydberg states of hydrogenlike ions allows highly-accurate predictions to be made for energy levels. In particular, uncertainties arising from the problematic nuclear size correction which beset low angular-momentum states are negligibly small for the high angular-momentum states. The largest remaining source of uncertainty can be addressed with the help of quantum electrodynamics (QED) calculations, including a new nonperturbative result reported here. More stringent tests of theory and an improved determination of the Rydberg constant may be possible if predictions can be compared with precision frequency measurements in this regime. The diversity of information can be increased by utilizing a variety of combinations of ions and Ryberg states to determine fundamental constants and test theory.Comment: 10 pages; LaTe

    Portable, high intensity isotopic neutron source provides increased experimental accuracy

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    Small portable, high intensity isotopic neutron source combines twelve curium-americium beryllium sources. This high intensity of neutrons, with a flux which slowly decreases at a known rate, provides for increased experimental accuracy

    Workplace Organization and Innovation

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    This study uses data on Canadian establishments to test whether particular organizational structures are correlated with the likelihood of adopting process and product innovations, controlling for the endogeneity of the predictors. We find that establishments with decentralized decision-making, information-sharing programs, or incentive pay plans are significantly more likely to innovate than other establishments. Larger establishments and those with a high vacancy rate are also more likely to innovate. These findings are consistent with a model in which workers hold information about production inefficiencies or consumer demands that can lead to productive innovations and that workplace organization attributes facilitate the communication and implementation of those ideas.Innovation, Decision-Making, Information-Sharing

    Black-Body Radiation Correction to the Polarizability of Helium

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    The correction to the polarizability of helium due to black-body radiation is calculated near room temperature. A precise theoretical determination of the black-body radiation correction to the polarizability of helium is essential for dielectric gas thermometry and for the determination of the Boltzmann constant. We find that the correction, for not too high temperature, is roughly proportional to a modified hyperpolarizability (two-color hyperpolarizability), which is different from the ordinary hyperpolarizability of helium. Our explicit calculations provide a definite numerical result for the effect and indicate that the effect of black-body radiation can be excluded as a limiting factor for dielectric gas thermometry using helium or argon.Comment: 8 pages; RevTe
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