7,352 research outputs found

    Electron stripping and re-attachment at atomic centers using attosecond half-cycle pulses

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    We investigate the response of two three-body Coulomb systems when driven by attosecond half-cycle pulses: The hydrogen molecular ion and the helium atom. Using very short half-cycle pulses (HCPs) which effectively deliver ``kicks'' to the electrons, we first study how a carefully chosen sequence of HCPs can be used to control to which of one of the two fixed atomic centers the electron gets re-attached. Moving from one electron in two atomic centers to two electrons in one atomic center we then study the double ionization from the ground state of He by a sequence of attosecond time-scale HCPs, with each electron receiving effectively a ``kick'' from each HCP. We investigate how the net electric field of the sequence of HCPs affects the total and differential ionization probabilities

    The electronic structure of pyrazine. Configuration interaction calculations using an extended basis

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    Extensive ab initio double zeta basis set configuration interaction calculations have been carried out on the nπ^∗ and ππ^∗ states of pyrazine as well as on the low‐lying n and π cations. The calculations corroborate the validity of the valence bond (VB) model for the interaction of lone pair excitations proposed earlier by Wadt and Goddard. Good agreement (errors of ∼0.2 eV) with experiment is obtained (except for the higher‐lying 1ππ∗ states that possess significant ionic character). The calculations indicate that the order of increasing ionization potentials is ^2A_g(n), 2B_(1g)(π), 2B_(1u)(n), and ^2B_(2g)(π). The forbidden 1 ^1B_(2g)(nπ^∗) state is predicted to be 1.30 eV above the allowed 1^ 1B_(3u)(nπ^∗) state. Finally, the calculations indicate that the adiabatic excitation energies to the 1^ 3B_1(nπ^∗) and 1^ 3A_1(ππ^∗) states in pyridine should be nearly degenerate at ∼3.6 eV

    Women and their birth partners' experiences following a primary postpartum haemorrhage: a qualitative study.

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    BACKGROUND: Postpartum haemorrhage (PPH) is a common obstetric complication. Rates of PPH are increasing in a number of developed countries. This is concerning as PPH is recognised as a leading cause of maternal morbidity and mortality which includes psychological and emotional distress. There is limited understanding of the emotional impact of PPH experienced by women and their birth partners. This study qualitatively describes the experiences of women and their birth partners who experienced a primary PPH. METHODS: Semi-structured interview study. Couples were recruited via maximum variation sampling, which, by purposive sampling drew participants from three groups depending on the degree of PPH: minor (500-1000 ml), moderate (1000-2000 ml) and severe (>2000 ml). Interviews took place from 4 to 14 months post birth, and data were analysed via Framework analysis. RESULTS: In this qualitative study, 11 women and six partners were interviewed. Data were organised into four interrelated themes; Control, Communication, Consequence, Competence. Just over half of the women and their birth partners were unaware they had a PPH, and would have preferred more information either at the time or in the postnatal period. The findings suggest that birth partners also required more information, especially if separated from their partner during the PPH. CONCLUSIONS: This study provides valuable insights into women's reports of their feelings and experiences during and after a PPH, and how their partners feel having observed a PPH. This study suggests that women who have had a PPH of any volume would like more information. Further investigations into the timings, methods and effectiveness of discussions following a PPH are recommended

    One-Electron Ionization of Multielectron Systems in Strong Nonresonant Laser Fields

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    We present a novel approach to calculating strong field ionization dynamics of multielectron molecular targets. Adopting a multielectron wavefunction ansatz based on field-free ab initio neutral and ionic multielectron states, a set of coupled time-dependent single-particle Schroedinger equations describing the neutral amplitude and continuum electron are constructed. These equations, amenable to direct numerical solution or further analytical treatment, allow one to study multielectron effects during strong field ionization, recollision, and high harmonic generation. We apply the method to strong field ionization of CO_2, and suggest the importance of intermediate core excitation to explain previous failure of analytical models to reproduce experimental ionization yields for this molecule.Comment: 25 pages, 6 figure

    Development and evaluation of a screening tool to identify people with diabetes at increased risk of medication problems relating to hypoglycaemia and medication non-adherence

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    Abstract Aims: To develop and evaluate a screening tool to identify people with diabetes at increased risk of medication problems relating to hypoglycaemia and medication non-adherence. Methods: A retrospective audit of attendances at a diabetes outpatient clinic at a public, teaching hospital over a 16-month period was conducted. Logistic regression was undertaken to examine risk factors associated with medication problems relating to hypoglycaemia and medication non-adherence and the most predictive set of factors comprise the Diabetes Medication Risk Screening Tool. Evaluating the tool involved assessing sensitivity and specificity, positive and negative predictive values, cut-off scores, inter-rater reliability, and content validity. Results: The Diabetes Medication Risk Screening Tool comprises seven predictive factors: age, living alone, English language, mental and behavioural problems, comorbidity index score, number of medications prescribed, and number of high-risk medications prescribed. The tool has 76.5% sensitivity, 59.5% specificity, and has a 65.1% positive predictive value, and a 71.8% negative predictive value. A score of 27 or more out of 62 was associated with high-risk of a medication problem. The inter-rater reliability of the tool was high (κ = 0.79, 95% CI 0.75 - 0.84) and the content validity index was 99.4%. Conclusion: The Diabetes Medication Risk Screening Tool has good psychometric properties and can proactively identify people with diabetes at greatest risk of medication problems relating to hypoglycaemia and medication non-adherence
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