52 research outputs found

    g factor of Li-like ions with nonzero nuclear spin

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    The fully relativistic theory of the g factor of Li-like ions with nonzero nuclear spin is considered for the (1s)^2 2s state. The magnetic-dipole hyperfine-interaction correction to the atomic g factor is calculated including the one-electron contributions as well as the interelectronic-interaction effects of order 1/Z. This correction is combined with the interelectronic-interaction, QED, nuclear recoil, and nuclear size corrections to obtain high-precision theoretical values for the g factor of Li-like ions with nonzero nuclear spin. The results can be used for a precise determination of nuclear magnetic moments from g factor experiments.Comment: 20 pages, 5 figure

    Isotope shift calculations for atoms with one valence electron

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    This work presents a method for the ab initio calculation of isotope shift in atoms and ions with one valence electron above closed shells. As a zero approximation we use relativistic Hartree-Fock and then calculate correlation corrections. The main motivation for developing the method comes from the need to analyse whether different isotope abundances in early universe can contribute to the observed anomalies in quasar absorption spectra. The current best explanation for these anomalies is the assumption that the fine structure constant, alpha, was smaller at early epoch. We test the isotope shift method by comparing the calculated and experimental isotope shift for the alkali and alkali-like atoms Na, MgII, K, CaII and BaII. The agreement is found to be good. We then calculate the isotope shift for some astronomically relevant transitions in SiII and SiIV, MgII, ZnII and GeII.Comment: 11 page

    Finding focus in a difficult landscape: Therapists’ experiences with challenging video guidance processes for parent–infant dyads

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    Marte Meo video guidance uses filmed interaction of the actual parent–infant dyad in the guidance of caregivers. Exploring the challenges that therapists meet in the guidance of parent–infant dyads may illuminate important aspects of the method itself as well as the therapists’ role and requirements. This could lead to method development and improved practice, but is hitherto little addressed. In this paper, we explore how skilled therapists experience and handle challenging or failing guidance processes with parent–infant dyads. We analyzed interviews with 13 Marte Meo therapists/supervisors using team-based reflexive thematic analysis. Four main themes were identified: promoting relational growth in a coercive context, building an alliance that feels safe for the parents, looking at positive moments in difficult lives, and handling intense feelings as a therapist. Our findings show that therapists experience specific therapeutic and ethical challenges with a vulnerable subgroup of parent–infant dyads where child protective issues arise, where caregivers’ insecurities impede the therapeutic relationship, and where caregivers have unsolved relational or mental health problems. The therapists’ role becomes pivotal and demanding with regard to the therapeutic alliance, the therapeutic interventions in the guidance process, and their own need for regulation, supervision, and structure. Identification of these vulnerable dyads early in the process could facilitate a better adaptation and practice of video guidance. Our findings suggest a need for supporting structures, clinical supervision, and training that address these challenges.publishedVersio

    Tensorial form and matrix elements of the relativistic nuclear recoil operator

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    Within the lowest-order relativistic approximation (v2/c2\sim v^2/c^2) and to first order in me/Mm_e/M, the tensorial form of the relativistic corrections of the nuclear recoil Hamiltonian is derived, opening interesting perspectives for calculating isotope shifts in the multiconfiguration Dirac-Hartree-Fock framework. Their calculation is illustrated for selected Li-, B- and C-like ions. The present work underlines the fact that the relativistic corrections to the nuclear recoil are definitively necessary for getting reliable isotope shift values.Comment: 22 pages, no figures, submitted to J. Phys.

    Index of refraction for cold lithium- and diatomic sodium waves traveling through cold noble gases

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    In the present paper we propose to measure the index of refraction for diatomic sodium molecules traveling through a cold helium gas. Theoretical calculations of the index of refraction for this system are presented as a function of the molecule velocity and atom gas temperature. Whereas previous theoretical efforts to compute the refractive index have been concerned with atomic systems and atomic matter waves, we extend the investigation to diatomic molecules in the present work. To enable such calculations the potential energy surface for the atom-molecule interaction is calculated ab initio, along with the long range dispersion coefficients for the atom-molecule system. The full close-coupled equations, describing the atom-molecule collisions, are solved numerically to work out the influence of the collisions on the matter waves. We investigate the sensitivity of the results upon changes and inaccuracies in the potential energy surface. Several molecular rotational levels are included in the present study, and the index of refraction is found to depend on the rotational state. In addition, the index of refraction for atomic lithium matter waves traveling through the cold noble gases helium and argon are computed, motivated by a recent experiment with atomic lithium matter waves. Different resonances (glory- and scattering resonances) are identified from the results. Such resonances offer an important opportunity for the comparison of experiment and theory

    'If there's no stability around them': Experienced therapists' view on the role of patients' social world in recovery in bipolar disorder

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    Background: Recovery in severe mental illness has traditionally been described as a deeply personal process. At the same time, researchers are increasingly attending to the social nature of such processes. In this article, we aim to sup‑ plement the growing knowledge base regarding these social aspects by exploring the perspectives of experienced therapists: how do they view the role of the social world in processes of healing and growth for people with bipolar disorder? And in what ways can the social world impede recovery? Methods: We conducted 12 semi-structured individual interviews and analyzed the resulting transcripts using a team-based thematic analysis method. Results: We identifed three themes: (a) establishing a sense of belonging; (b) backing ongoing therapy; and (c) relational ripple efects. Conclusions: We relate our fndings to existing theory and research, discuss clinical implications, and highlight study limitations. We argue that our fndings underscore the need to integrate an understanding of recovery as a personal and social process in the mental health care services that we provide

    Ultra-Short Lived Non-Rydberg Doubly Excited Resonances Observed in Molecular Photoionization of CO and N2\text{}_{2} Molecules

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    Our group has recently carried out measurements of dispersed fluorescence from photo-excited N2\text{}_{2} and CO molecules in 19-34 eV excitation energy range using the Swedish synchrotron radiation facility MAX in Lund. The experimental results show that relative intensities of the fluorescence from different vibrational levels of the excited N2+\text{}_{2}^{+} and CO+\text{}^{+} vary with the excitation energy. We associate this phenomenon with the existence of doubly excited states in N2\text{}_{2} and CO in the corresponding energy regions. Our results show that the widths of the newly revealed states correspond to their lifetimes of the order of few femtoseconds
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