Oscillator strengths with pseudopotentials

The time-dependent local-density approximation (TDLDA) is shown to remain accurate in describing the atomic response of IB elements under the additional approximation of using pseudopotentials to treat the effects of core electrons. This extends the work of Zangwill and Soven who showed the utility of the all-electron TDLDA in the atomic response problem.Comment: 13 pages including 3 Postscript figure

Optogalvanic Spectroscopy of Metastable States in Yb^{+}

The metastable ^{2}F_{7/2} and ^{2}D_{3/2} states of Yb^{+} are of interest for applications in metrology and quantum information and also act as dark states in laser cooling. These metastable states are commonly repumped to the ground state via the 638.6 nm ^{2}F_{7/2} -- ^{1}D[5/2]_{5/2} and 935.2 nm ^{2}D_{3/2} -- ^{3}D[3/2]_{1/2} transitions. We have performed optogalvanic spectroscopy of these transitions in Yb^{+} ions generated in a discharge. We measure the pressure broadening coefficient for the 638.6 nm transition to be 70 \pm 10 MHz mbar^{-1}. We place an upper bound of 375 MHz/nucleon on the 638.6 nm isotope splitting and show that our observations are consistent with theory for the hyperfine splitting. Our measurements of the 935.2 nm transition extend those made by Sugiyama et al, showing well-resolved isotope and hyperfine splitting. We obtain high signal to noise, sufficient for laser stabilisation applications.Comment: 8 pages, 5 figure

Relativistic calculations of isotope shifts in highly charged ions

The isotope shifts of forbidden transitions in Be- and B-like argon ions are calculated. It is shown that only using the relativistic recoil operator can provide a proper evaluation of the mass isotope shift, which strongly dominates over the field isotope shift for the ions under consideration. Comparing the isotope shifts calculated with the current experimental uncertainties indicates very good perspectives for a first test of the relativistic theory of the recoil effect in middle-Z ions

Radiative Corrections to One-Photon Decays of Hydrogenic Ions

Radiative corrections to the decay rate of n=2 states of hydrogenic ions are calculated. The transitions considered are the M1 decay of the 2s state to the ground state and the E1(M2) decays of the $2p_{1/2}$ and $2p_{3/2}$ states to the ground state. The radiative corrections start in order $\alpha (Z \alpha)^2$, but the method used sums all orders of $Z\alpha$. The leading $\alpha (Z\alpha)^2$ correction for the E1 decays is calculated and compared with the exact result. The extension of the calculational method to parity nonconserving transitions in neutral atoms is discussed.Comment: 22 pages, 2 figure

Diagnostic management of acute pulmonary embolism: a prediction model based on a patient data meta-analysis

AimsRisk stratification is used for decisions regarding need for imaging in patients with clinically suspected acute pulmonary embolism (PE). The aim was to develop a clinical prediction model that provides an individualized, accurate probability estimate for the presence of acute PE in patients with suspected disease based on readily available clinical items and D-dimer concentrations.Methods and resultsAn individual patient data meta-analysis was performed based on sixteen cross-sectional or prospective studies with data from 28 305 adult patients with clinically suspected PE from various clinical settings, including primary care, emergency care, hospitalized and nursing home patients. A multilevel logistic regression model was built and validated including ten a priori defined objective candidate predictors to predict objectively confirmed PE at baseline or venous thromboembolism (VTE) during follow-up of 30 to 90 days. Multiple imputation was used for missing data. Backward elimination was performed with a P-value ConclusionThe present model provides an absolute, individualized probability of PE presence in a broad population of patients with suspected PE, with very good discrimination and calibration. Its clinical utility needs to be evaluated in a prospective management or impact study.Thrombosis and Hemostasi

SOFTWARE FOR RELATIVISTIC ATOMIC THEORY : THE GRASP PROJECT AT OXFORD

GRASP est l'acronyme de General-purpose Relativistic Atomic Structure Program. Ce progiciel est essentiellement un code Dirac-Fock multiconfigurationnel (MCDF) convivial basé sur l'algèbre de Racah et les méthodes de différences finies. Nous décrivons ici brièvement le formalisme MCDF dans le contexte du projet GRASP à Oxford.GRASP is an acronym for General-purpose Relativistic Atomic Structure Program. This package is essentially a user-friendly multiconfiguration Dirac-Fock (MCDF) code based on the Racah Algebra and finite-difference methods. We describe briefly the MCDF formalism in the context of the GRASP project at Oxford

Energy Levels and Electric Dipole Transitions for Neutral Actinium (Z=89)

We have reported a relativistic multiconfiguration Dirac-Fock calculation including Breit and quantum electrodynamic contributions on the level structure of atomic actinium, Ac I (Z = 89). The computations have been carried out for the low 45 even and 60 odd-parity levels, and the electric dipole transition parameters (wavelengths, oscillator strengths and transition probabilities) for some transitions between these levels. Comparison has been also made with other results in available literature

Safety and Efficiency of Diagnostic Strategies for Ruling Out Pulmonary Embolism in Clinically Relevant Patient Subgroups A Systematic Review and Individual-Patient Data Meta-analysis

Background: How diagnostic strategies for suspected pulmonary embolism (PE) perform in relevant patient subgroups defined by sex, age, cancer, and previous venous thromboembolism (VTE) is unknown. Purpose: To evaluate the safety and efficiency of the Wells and revised Geneva scores combined with fixed and adapted D-dimer thresholds, as well as the YEARS algorithm, for ruling out acute PE in these subgroups. Data Sources: MEDLINE from 1 January 1995 until 1 January 2021. Study Selection: 16 studies assessing at least 1 diagnostic strategy. Data Extraction: Individual-patient data from 20553 patients. Data Synthesis: Safety was defined as the diagnostic failure rate (the predicted 3-month VTE incidence after exclusion of PE without imaging at baseline). Efficiency was defined as the proportion of individuals classified by the strategy as "PE con -sidered excluded" without imaging tests. Across all strategies, efficiency was highest in patients younger than 40 years (47% to 68%) and lowest in patients aged 80 years or older (6.0% to 23%) or patients with cancer (9.6% to 26%). However, efficiency improved considerably in these subgroups when pretest probabil-ity-dependent D-dimer thresholds were applied. Predicted failure rates were highest for strategies with adapted D-dimer thresh-olds, with failure rates varying between 2% and 4% in the pre-defined patient subgroups. Limitations: Between-study differences in scoring predictor items and D-dimer assays, as well as the presence of differential verifica-tion bias, in particular for classifying fatal events and subsegmental PE cases, all of which may have led to an overestimation of the predicted failure rates of adapted D-dimer thresholds. Conclusion: Overall, all strategies showed acceptable safety, with pretest probability-dependent D-dimer thresholds having not only the highest efficiency but also the highest predicted failure rate. From an efficiency perspective, this individual-patient data meta-analysis supports application of adapted D-dimer thresholds. Primary Funding Source: Dutch Research Council. (PROSPERO: CRD42018089366)Thrombosis and Hemostasi