On the astrophysical robustness of neutron star merger r-process

In this study we explore the nucleosynthesis in the dynamic ejecta of compact binary mergers. We are particularly interested in the question how sensitive the resulting abundance patterns are to the parameters of the merging system. Therefore, we systematically investigate combinations of neutron star masses in the range from 1.0 to 2.0 \Msun and, for completeness, we compare the results with those from two simulations of a neutron star black hole merger. The ejecta masses vary by a factor of five for the studied systems, but all amounts are (within the uncertainties of the merger rates) compatible with being a major source of cosmic r-process. The ejecta undergo a robust r-process nucleosynthesis which produces all the elements from the second to the third peak in close-to-solar ratios. Most strikingly, this r-process is extremely robust, all 23 investigated binary systems yield practically identical abundance patterns. This is mainly the result of the ejecta being extremely neutron rich (\ye $\approx0.04$) and the r-process path meandering along the neutron drip line so that the abundances are determined entirely by nuclear rather than by astrophysical properties. This robustness together with the ease with which both the second and third peak are reproduced make compact binary mergers the prime candidate for the source of the observed unique heavy r-process component.Comment: accepted for publication in MNRA

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津田純子

Gallium self-interstitial relaxation in Gallium Arsenide: an {ab initio} characterization

Ga interstitials in GaAs ($I_{Ga}$) are studied using the local-orbital {ab-initio} code SIESTA in a supercell of {216+1} atoms. Starting from eight different initial configurations, we find five metastable structures: the two tetrahedral sites in addition to the 110-split$\mathrm{_{[Ga-As]}}$, 111-split$\mathrm{_{[Ga-As]}}$, and 100-split$\mathrm{_{[Ga-Ga]}}$. Studying the competition between various configuration and charges of $I_{Ga}$, we find that predominant gallium interstitials in GaAs are charged +1, neutral or at most -1 depending on doping conditions and prefer to occupy the tetrahedral configuration where it is surrounded by Ga atoms. Our results are in excellent agreement with recent experimental results concerning the dominant charge of $I_{Ga}$, underlining the importance of finite size effects in the calculation of defects.Comment: v1) 18 pages, 5 figures, submitted to PRB (Latex preprint version) v2) 9 pages, 5 figures, reviewed version resubmitted to PRB (correction to equation 1, some changes and reformulations, minor grammatical and typo corrections, added reference

Magnetorotationally driven Supernovae as the origin of early galaxy rr-process elements?

We examine magnetorotationally driven supernovae as sources of $r$-process elements in the early Galaxy. On the basis of thermodynamic histories of tracer particles from a three-dimensional magnetohydrodynamical core-collapse supernova model with approximated neutrino transport, we perform nucleosynthesis calculations with and without considering the effects of neutrino absorption reactions on the electron fraction ($Y_{e}$) during post-processing. We find that the peak distribution of $Y_{e}$ in the ejecta is shifted from $\sim0.15$ to $\sim0.17$ and broadened toward higher $Y_{e}$ due to neutrino absorption. Nevertheless, in both cases the second and third peaks of the solar $r$-process element distribution can be well reproduced. The rare progenitor configuration that was used here, characterized by a high rotation rate and a large magnetic field necessary for the formation of bipolar jets, could naturally provide a site for the strong $r$-process in agreement with observations of the early galactic chemical evolution.Comment: 5 pages, 4 figure

Boron depletion in 9 to 15 M(circle dot) stars with rotation

The treatment of mixing is still one of the major uncertainties in stellar evolution models. One open question is how well the prescriptions for rotational mixing describe the real effects. We tested the mixing prescriptions included in the Geneva stellar evolution code (GENEC) by following the evolution of surface abundances of light isotopes in massive stars, such as boron and nitrogen. We followed 9, 12 and 15 M(O) models with rotation from the zero age main sequence up to the end of He burning. The calculations show the expected behaviour with faster depletion of boton for faster rotating stars and more massive stars. The mixing at the surface is more efficient, than predicted by prescriptions used in other codes and reproduces the majority of observations very well However two observed stars with strong boron depletion but, no nitrogen enhancement still can not be explained and let the question open whether additional mixing processes are acting in these massive star

Change over time in functional capacity and self-perceived health status for patients with chronic musculoskeletal pain: a registry-based longitudinal study.

BACKGROUND AND AIMS Chronic musculoskeletal pain is a major public health problem worldwide. Both self-reported functional capacity and self-perceived health status are reduced in patients with chronic musculoskeletal pain. Previous studies mostly assessed functional capacity through self-reported questionnaires instead of objective measurements. The aim of this study, therefore, is to assess the amount of change over time and its clinical meaningfulness in functional capacity and self-perceived health status of patients with chronic musculoskeletal pain undergoing Bern Ambulatory Interprofessional Rehabilitation (BAI-Reha). METHODS The registry-based longitudinal cohort study with prospectively collected data from a rehabilitation programme took place in a real-life setting. Patients (n = 81) with chronic musculoskeletal pain took part in the BAI-Reha. The main outcomes were the six-minute-walk test (6MWT), the safe maximum floor-to-waist lift (SML) and the European Quality of Life and Health measure visual analogue scale (EQ VAS). Timepoints of measurement were at baseline and post-BAI-Reha (i.e., at 4 months). The quantity of interest was the adjusted time effect (point estimate, 95% confidence interval, and p-value for testing the null hypothesis of no change over time). Statistical significance (α = 0.05) and clinical meaningfulness of the mean value change over time were assessed using predefined thresholds (six-minute-walk test 50 m, SML 7 kg, and EQ VAS 10 points). RESULTS The linear mixed model analysis showed a statistically significant change over time for the six-minute-walk test (mean value change 56.08 m, 95% CI [36.13, 76.03]; p <0.001), SML (mean value change 3.92 kg, 95% CI [2.66, 5.19]; p <0.001), and EQ VAS (mean value change 9.58 points, 95% CI [4.87, 14.28]; p <0.001). Moreover, the improvement in the six-minute-walk test is clinically meaningful (mean value change 56.08 m) and almost clinically meaningful (mean value change 9.58 points) in the EQ VAS. CONCLUSION Patients walk further, lift more weight, and feel healthier after interprofessional rehabilitation when compared to baseline measurement. These findings confirm and add to previous results. IMPLICATIONS We encourage other providers of rehabilitation for patients with chronic musculoskeletal pain to measure functional capacity with objective outcome variables and to use self-reported outcome measures in addition to self-perceived health status. The well-established assessments used in this study are suitable for this purpose

The Role of Fission in Neutron Star Mergers and Its Impact on the r-Process Peaks

Comparing observational abundance features with nucleosynthesis predictions of stellar evolution or explosion simulations, we can scrutinize two aspects: (a) the conditions in the astrophysical production site and (b) the quality of the nuclear physics input utilized. We test the abundance features of r-process nucleosynthesis calculations for the dynamical ejecta of neutron star merger simulations based on three different nuclear mass models: The Finite Range Droplet Model, the (quenched version of the) Extended Thomas Fermi Model with Strutinsky Integral, and the Hartree-Fock-Bogoliubov mass model. We make use of corresponding fission barrier heights and compare the impact of four different fission fragment distribution models on the final r-process abundance distribution. In particular, we explore the abundance distribution in the second r-process peak and the rare-earth sub-peak as a function of mass models and fission fragment distributions, as well as the origin of a shift in the third r-process peak position. The latter has been noticed in a number of merger nucleosynthesis predictions. We show that the shift occurs during the r-process freeze-out when neutron captures and β-decays compete and an (n,γ)-(γ,n) equilibrium is no longer maintained. During this phase neutrons originate mainly from fission of material above A = 240. We also investigate the role of β-decay half-lives from recent theoretical advances, which lead either to a smaller amount of fissioning nuclei during freeze-out or a faster (and thus earlier) release of fission neutrons, which can (partially) prevent this shift and has an impact on the second and rare-earth peak as well.Peer reviewe

Boron depletion in 9 to 15 M stars with rotation

The treatment of mixing is still one of the major uncertainties in stellar evolution models. One open question is how well the prescriptions for rotational mixing describe the real effects. We tested the mixing prescriptions included in the Geneva stellar evolution code (GENEC) by following the evolution of surface abundances of light isotopes in massive stars, such as boron and nitrogen. We followed 9, 12 and 15 M models with rotation from the zero age main sequence up to the end of He burning. The calculations show the expected behaviour with faster depletion of boron for faster rotating stars and more massive stars. The mixing at the surface is more efficient than predicted by prescriptions used in other codes and reproduces the majority of observations very well. However two observed stars with strong boron depletion but no nitrogen enrichment still can not be explained and let the question open whether additional mixing processes are acting in these massive star

Walking and running with non-specific chronic low back pain: what about the lumbar lordosis angle?

Non-specific chronic low back pain (NSCLBP) is a major health problem, affecting about one fifth of the population worldwide. To avoid further pain or injury, patients with NSCLBP seem to adopt a stiffer movement pattern during everyday living activities. However, it remains unknown how NSCLBP affects the lumbar lordosis angle (LLA) during repetitive activities such as walking or running. This pilot study therefore aimed at exploring possible NSCLBP-related alterations in LLAs during walking and running by focusing on discrete parameters as well as continuous data. Thirteen patients with NSCLBP and 20 healthy pain-free controls were enrolled and underwent a full-body movement analysis involving various everyday living activities such as standing, walking and running. LLAs were derived from markers placed on the spinous processes of the vertebrae L1-L5 and S1. Possible group differences in discrete (average and range of motion (ROM)) and continuous LLAs were analyzed descriptively using mean differences with confidence intervals ranging from 95% to 75%. Patients with NSCLBP indicated reduced average LLAs during standing, walking and running and a tendency for lower LLA-ROM during walking. Analyses of continuous data indicated the largest group differences occurring around 25% and 70% of the walking and 25% and 75% of the running cycle. Furthermore, patients indicated a reversed movement pattern during running, with increasing instead of a decreasing LLAs after foot strike. This study provides preliminary evidence that NSCLBP might affect LLAs during walking and running. These results can be used as a basis for future large-scale investigations involving hypothesis testing.Comment: This is the accepted manuscript version of an article published in the Journal of Biomechanics (https://doi.org/10.1016/j.jbiomech.2020.109883