6,738 research outputs found

    Structure and three-body decay of 9^9Be resonances

    Get PDF
    The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying 9^9Be resonances into one neutron and two α\alpha-particles. We investigate the six resonances above the break-up threshold and below 6 MeV: 1/2±1/2^\pm, 3/2±3/2^\pm and 5/2±5/2^\pm. The short-distance properties of each resonance are studied, and the different angular momentum and parity configurations of the 8^8Be and 5^5He two-body substructures are determined. We compute the branching ratio for sequential decay via the 8^8Be ground state which qualitatively is consistent with measurements. We extract the momentum distributions after decay directly into the three-body continuum from the large-distance asymptotic structures. The kinematically complete results are presented as Dalitz plots as well as projections on given neutron and α\alpha-energy. The distributions are discussed and in most cases found to agree with available experimental data.Comment: 12 pages, 10 figures. To appear in Physical Review

    Momentum distributions from three-body decaying 9Be and 9B resonances

    Get PDF
    The complex-rotated hyperspherical adiabatic method is used to study the decay of low-lying 9^9Be and 9^9B resonances into α\alpha, α\alpha and nn or pp. We consider six low-lying resonances of 9^9Be (1/2±1/2^\pm, 3/2±3/2^\pm and 5/2±5/2^\pm) and one resonance of 9^9B (5/25/2^-) to compare with. The properties of the resonances at large distances are decisive for the momentum distributions of the three decaying fragments. Systematic detailed energy correlations of Dalitz plots are presented.Comment: 4 pages, 2 figures. Proceedings of the SOTANCP2 conference held in Brussels in May 201

    Few-body decay and recombination in nuclear astrophysics

    Get PDF
    Three-body continuum problems are investigated for light nuclei of astrophysical relevance. We focus on three-body decays of resonances or recombination via resonances or the continuum background. The concepts of widths, decay mechanisms and dynamic evolution are discussed. We also discuss results for the triple α\alpha decay in connection with 2+2^+ resonances and density and temperature dependence rates of recombination into light nuclei from α\alpha-particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body Conference held in Salamanca (Spain) in August-September 201

    Three-body structure of low-lying 18Ne states

    Full text link
    We investigate to what extent 18Ne can be descibed as a three-body system made of an inert 16O-core and two protons. We compare to experimental data and occasionally to shell model results. We obtain three-body wave functions with the hyperspherical adiabatic expansion method. We study the spectrum of 18Ne, the structure of the different states and the predominant transition strengths. Two 0+, two 2+, and one 4+ bound states are found where they are all known experimentally. Also one 3+ close to threshold is found and several negative parity states, 1-, 3-, 0-, 2-, most of them bound with respect to the 16O excited 3- state. The structures are extracted as partial wave components, as spatial sizes of matter and charge, and as probability distributions. Electromagnetic decay rates are calculated for these states. The dominating decay mode for the bound states is E2 and occasionally also M1.Comment: 17 pages, 5 figures (version to appear in EPJA

    Association between chronic irritability and depressive symptoms in children and adolescents.

    Get PDF
    Association between chronic irritability and depressive symptoms in children and adolescents. Busto-Garrido, M.; Gutierrez-Castillo, D; Navas- Gonzalez, JR; Gutierrez-Bedmar, M; Gutierrez-Casares, JR; Martin-Lunar, MT; Rodríguez-Rosado, A; Pena-Andreu, JM. European Psychiatry 415(2017) 5221.Chronic irritability is the most frequently reported symptom in child and adolescent depression. The association of both has been linked with high rates of chronicity, comorbility and impairment. Objectives To study the association between chronic irritability and depressive symptoms in children and adolescents. Methods We have studied 857 participants recruited from the only Child and Adolescent Mental Health Clinic in a catchment area of 122968 people under 18 (2004-2010). A sample of 677 participants (57 controls and 620 patients) was included to carry out a cross-sectional study. Chronic irritability was measured by a Visual Analog Scale (VAS irritability) -scored from 0 to 10-, and depressive symptoms by the Children's Depression Inventory (CDI). The participants were categorized into controls and patients, and according to their chronic irritability (≤4 [I],5 [II] and ≥6 [III]). The mean of CDI score was calculated for each of the groups, adjusted by sex and age, and analyzed by ANCOVA. Results The following means were obtained from the controls: 13,71 (group I), 9,82 (group II) and 17,45 (group III). Regarding to the patients: 13,92 (group I), 11,54 (group II) and 15,64 (group III). A quadratic association (p <0,0015) was found between VAS irritability score and CDI score. Conclussions There is not a lineal association between chronic irritability and depressive symptoms in children and adolescent. High rates of depressive symptoms were associated both with high and low rates of irritability. Several questions remain unexplained about the status of irritability in psychiatry as Stringaris group has been pointed out. Disclosure statement I have no potential conflict of interest to discloseUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Direct and sequential radiative three-body reaction rates at low temperatures

    Get PDF
    We investigate the low-temperature reaction rates for radiative capture processes of three particles. We compare direct and sequential capture mechanisms and rates using realistic phenomenological parametrizations of the corresponding photodissociation cross sections.Energy conservation prohibits sequential capture for energies smaller than that of the intermediate two-body structure. A finite width or a finite temperature allows this capture mechanism. We study generic effects of positions and widths of two- and three-body resonances for very low temperatures. We focus on nuclear reactions relevant for astrophysics, and we illustrate with realistic estimates for the α\alpha-α\alpha-α\alpha and α\alpha-α\alpha-nn radiative capture processes. The direct capture mechanism leads to reaction rates which for temperatures smaller than 0.1 GK can be several orders of magnitude larger than those of the NACRE compilation.Comment: To be published in European Physical Journal

    Joint effect of physical activity and sedentary behaviour on cardiovascular risk factors in Chilean adults

    Get PDF
    Background: To investigate the associations between combined categories of moderate-to-vigorous physical activity (MVPA) and sedentary behaviour (SB) with markers of adiposity and cardiovascular risk in adults. Methods: Overall, 5040 participants (mean age 46.4 years and 59.3% women) from the cross-sectional Chilean National Health Survey 2009–2010 were included in this study. MVPA and SB were measured using the Global Physical Activity questionnaire. Four categories were computed using MVPA- and SB-specific cut-offs (‘High-SB &#38; Active’, ‘Low-SB &#38; Active’, ‘High-SB &#38; Inactive’ and ‘Low-SB &#38; Inactive’). Results: Compared to the reference group (‘High-SB &#38; Inactive’), those in ‘High-SB &#38; Active’ and ‘Low-SB &#38; Active’ were less likely to have an obese BMI (OR: 0.67 [0.54; 0.85], P = 0.0001 and 0.74 [0.59; 0.92] P = 0.0007, respectively) and less likely to have metabolic syndrome (OR: 0.63 [0.49; 0.82], P &lt; 0.0001 and 0.72 [0.57; 0.91], P = 0.007), central obesity (OR: 0.79 [0.65; 0.96], P = 0.016 and 0.71 [0.59; 0.84], P &lt; 0.0001), diabetes (OR: 0.45 [0.35; 0.59], P &lt; 0.0001 and 0.44 [0.34; 0.56], P &lt; 0.0001) and hypertension (OR: 0.52 [0.43; 0.63], P &lt; 0.0001 and 0.60 [0.50; 0.72], P &lt; 0.0001), respectively. Conclusions: Being physically active and spending less time in SBs was associated with lower adiposity and improvements in cardiovascular risk factors
    corecore