121 research outputs found

    Electron-correlation effects in the gg-factor of light Li-like ions

    Full text link
    We investigate electron-correlation effects in the gg-factor of the ground state of Li-like ions. Our calculations are performed within the nonrelativistic quantum electrodynamics (NRQED) expansion up to two leading orders in the fine-structure constant α\alpha, α2\alpha^2 and α3\alpha^3. The dependence of the NRQED results on the nuclear charge number ZZ is studied and the individual 1/Z1/Z-expansion contributions are identified. Combining the obtained data with the results of the all-order (in ZαZ\alpha) calculations performed within the 1/Z1/Z expansion, we derive the unified theoretical predictions for the gg-factor of light Li-like ions.Comment: 9 pages, 4 table

    Coefficients of Friction for Apple on Various Surfaces as Affected by Velocity

    Full text link
    Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a Technical Paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 5 (2003): C. Puchalski, G. Brusewitz, and Z. Slipek. Coefficients of Friction for Apple on Various Surfaces as Affected by Velocity. Vol. V. December 2003

    Self-energy screening effects in the gg factor of Li-like ions

    Full text link
    We report an investigation of the self-energy screening effects for the gg factor of the ground state of Li-like ions. The leading screening contribution of the relative order 1/Z1/Z is calculated to all orders in the binding nuclear strength parameter ZαZ\alpha (where ZZ is the nuclear charge number and α\alpha is the fine-structure constant). We also extend the known results for the ZαZ\alpha expansion of the QED screening correction by deriving the leading logarithmic contribution of order α5lnα\alpha^5\ln\alpha and obtaining approximate results for the α5\alpha^5 and α6\alpha^6 contributions. The comparison of the two approaches yields a stringent check of consistency of the two calculations and allows us to obtain improved estimations of the higher-order screening effects.Comment: Several misprints are corrected in ver.3; Sec. VI is updated in ver.

    Isotope Shift Measurements of Stable and Short-Lived Lithium Isotopes for Nuclear Charge Radii Determination

    Get PDF
    Changes in the mean-square nuclear charge radii along the lithium isotopic chain were determined using a combination of precise isotope shift measurements and theoretical atomic structure calculations. Nuclear charge radii of light elements are of high interest due to the appearance of the nuclear halo phenomenon in this region of the nuclear chart. During the past years we have developed a new laser spectroscopic approach to determine the charge radii of lithium isotopes which combines high sensitivity, speed, and accuracy to measure the extremely small field shift of an 8 ms lifetime isotope with production rates on the order of only 10,000 atoms/s. The method was applied to all bound isotopes of lithium including the two-neutron halo isotope Li-11 at the on-line isotope separators at GSI, Darmstadt, Germany and at TRIUMF, Vancouver, Canada. We describe the laser spectroscopic method in detail, present updated and improved values from theory and experiment, and discuss the results.Comment: 34 pages, 24 figures, 14 table

    Redefining Palliative Care-A New Consensus-Based Definition.

    Get PDF
    The International Association for Hospice and Palliative Care developed a consensus-based definition of palliative care (PC) that focuses on the relief of serious health-related suffering, a concept put forward by the Lancet Commission Global Access to Palliative Care and Pain Relief. The main objective of this article is to present the research behind the new definition. The three-phased consensus process involved health care workers from countries in all income levels. In Phase 1, 38 PC experts evaluated the components of the World Health Organization definition and suggested new/revised ones. In Phase 2, 412 International Association for Hospice and Palliative Care members in 88 countries expressed their level of agreement with the suggested components. In Phase 3, using results from Phase 2, the expert panel developed the definition. The consensus-based definition is as follows: Palliative care is the active holistic care of individuals across all ages with serious health-related suffering due to severe illness and especially of those near the end of life. It aims to improve the quality of life of patients, their families and their caregivers. The definition includes a number of bullet points with additional details as well as recommendations for governments to reduce barriers to PC. Participants had significantly different perceptions and interpretations of PC. The greatest challenge faced by the core group was trying to find a middle ground between those who think that PC is the relief of all suffering and those who believe that PC describes the care of those with a very limited remaining life span

    Redefining palliative care-a new consensus-based definition

    Get PDF
    Context: The International Association for Hospice and Palliative Care developed a consensus-based definition of palliative care (PC) that focuses on the relief of serious health-related suffering, a concept put forward by the Lancet Commission Global Access to Palliative Care and Pain Relief. Objective: The main objective of this article is to present the research behind the new definition. Methods: The three-phased consensus process involved health care workers from countries in all income levels. In Phase 1, 38 PC experts evaluated the components of the World Health Organization definition and suggested new/revised ones. In Phase 2, 412 International Association for Hospice and Palliative Care members in 88 countries expressed their level of agreement with the suggested components. In Phase 3, using results from Phase 2, the expert panel developed the definition. Results: The consensus-based definition is as follows: Palliative care is the active holistic care of individuals across all ages with serious health-related suffering due to severe illness and especially of those near the end of life. It aims to improve the quality of life of patients, their families and their caregivers. The definition includes a number of bullet points with additional details as well as recommendations for governments to reduce barriers to PC. Conclusion: Participants had significantly different perceptions and interpretations of PC. The greatest challenge faced by the core group was trying to find a middle ground between those who think that PC is the relief of all suffering and those who believe that PC describes the care of those with a very limited remaining life span

    Experimental progress in positronium laser physics

    Get PDF
    corecore