Boston University Brussels

We investigate the nucleosynthesis and kilonova properties of binary neutron-star (NS) merger models which lead to intermediate remnant lifetimes of ~0.1-1seconds until black-hole (BH) formation and describe all components of material ejected during the dynamical merger phase, NS-remnant evolution, and final viscous disintegration of the BH torus after gravitational collapse. To this end we employ a combination of hydrodynamics, nucleosynthesis, and radiative-transfer tools to achieve a consistent end-to-end modeling of the system and its observables. We adopt a novel version of the Shakura-Sunyaev scheme allowing to vary the approximate turbulent viscosity inside the NS remnant independently of the surrounding disk. We find that asymmetric progenitors lead to shorter remnant lifetimes and enhanced ejecta masses, although the viscosity affects the absolute values of these characteristics. The integrated production of lanthanides and heavier elements in such binary systems is sub-solar, suggesting that the considered scenarios contribute in a sub-dominant fashion to r-process enrichment. One reason is that BH-tori formed after delayed collapse exhibit less neutron-rich conditions than typically found, and often assumed in previous BH-torus models, for early BH formation. The outflows in our models feature strong anisotropy as a result of the lanthanide-poor polar neutrino-driven wind pushing aside lanthanide-rich dynamical ejecta. Considering the complexity of the models, the estimated kilonova light curves show promising agreement with AT2017gfo after times of several days, while the remaining inconsistencies at early times could possibly be overcome in binary configurations with a more dominant neutrino-driven wind relative to the dynamical ejecta.

Black-hole (BH) accretion disks formed in compact-object mergers or collapsars may be major sites of the rapid-neutron-capture (r-)process, but the conditions determining the electron fraction (Y_e) remain uncertain given the complexity of neutrino transfer and angular-momentum transport. After discussing relevant weak-interaction regimes, we study the role of neutrino absorption for shaping Y_e using an extensive set of simulations performed with two-moment neutrino transport and again without neutrino absorption. We vary the torus mass, BH mass and spin, and examine the impact of rest-mass and weak-magnetism corrections in the neutrino rates. We also test the dependence on the angular-momentum transport treatment by comparing axisymmetric models using the standard alpha-viscosity with viscous models assuming constant viscous length scales (l_t) and three-dimensional magnetohydrodynamic (MHD) simulations. Finally, we discuss the nucleosynthesis yields and basic kilonova properties. We find that absorption pushes Y_e towards ~0.5 outside the torus, while inside increasing the equilibrium value Y_e^eq by ~0.05-0.2. Correspondingly, a substantial ejecta fraction is pushed above Y_e=0.25, leading to a reduced lanthanide fraction and a brighter, earlier, and bluer kilonova than without absorption. More compact tori with higher neutrino optical depth, tau, tend to have lower Y_e^eq up to tau~1-10, above which absorption becomes strong enough to reverse this trend. Disk ejecta are less (more) neutron-rich when employing an l_t=const. viscosity (MHD treatment). The solar-like abundance pattern found for our MHD model marginally supports collapsar disks as major r-process sites, although a strong r-process may be limited to phases of high mass-infall rates, Mdot>~ 2 x 10^(-2) Msun/s.

Abstract Study design: One-way, mixed, real experimental RCT study. Background: A multimodal physiotherapeutic approach to treat non-specific (NSP) Chronic Low Back Pain (CLBP), may affect the quality of life

This study assessed non-inferiority of parecoxib vs. combination parecoxib+propacetamol and compared the opioid-sparing effects of parecoxib, propacetamol, and parecoxib+propacetamol vs. placebo after total hip arthroplasty. In this randomized, placebo-controlled, parallel-group, non-inferiority study, patients received one of four IV treatments after surgery: parecoxib 40 mg bid (n = 72); propacetamol 2 g qid (n = 71); parecoxib 40 mg bid plus propacetamol 2 g qid (n = 72); or placebo (n = 38) with supplemental IV patient-controlled analgesia (morphine). Patients and investigators were blinded to treatment. Pain intensity at rest and with movement was assessed regularly, together with functional recovery (modified Brief Pain Inventory-Short Form) and opioid-related side effects (Opioid-Related Symptom Distress Scale) questionnaires up to 48 h. After 24 h, cumulative morphine consumption was reduced by 59.8% (P < 0.001), 38.9% (P < 0.001), and 26.8% (P = 0.005) in the parecoxib+propacetamol, parecoxib, and propacetamol groups, respectively, compared with placebo. Parecoxib did not meet criteria for non-inferiority to parecoxib+propacetamol. Parecoxib+propacetamol and parecoxib significantly reduced least-squares mean pain intensity scores at rest and with movement compared with propacetamol (P < 0.05). One day after surgery, parecoxib+propacetamol significantly reduced opioid-related symptom distress and decreased pain interference with function compared with propacetamol or placebo. Parecoxib and parecoxib+propacetamol provided significant opioid-sparing efficacy compared with placebo; non-inferiority of parecoxib to parecoxib+propacetamol was not demonstrated. Opioid-sparing efficacy was accompanied by significant reductions in pain intensity on movement, improved functional outcome, and less opioid-related symptom distress. Study medications were well tolerated.

We present a comprehensive study of r-process element nucleosynthesis in the ejecta of compact binary mergers (CBMs) and their relic black-hole (BH)-torus systems. The evolution of the BH-accretion tori is simulated for seconds with a Newtonian hydrodynamics code including viscosity effects, pseudo-Newtonian gravity for rotating BHs, and an energy-dependent two-moment closure scheme for the transport of electron neutrinos and antineutrinos. The investigated cases are guided by relativistic double neutron star (NS-NS) and NS-BH merger models, producing ~3-6 Msun BHs with rotation parameters of A~0.8 and tori of 0.03-0.3 Msun. Our nucleosynthesis analysis includes the dynamical (prompt) ejecta expelled during the CBM phase and the neutrino and viscously driven outflows of the relic BH-torus systems. While typically ~20-25% of the initial accretion-torus mass are lost by viscously driven outflows, neutrino-powered winds contribute at most another ~1%, but neutrino heating enhances the viscous ejecta significantly. Since BH-torus ejecta possess a wide distribution of electron fractions (0.1-0.6) and entropies, they produce heavy elements from A~80 up to the actinides, with relative contributions of A>130 nuclei being subdominant and sensitively dependent on BH and torus masses and the exact treatment of shear viscosity. The combined ejecta of CBM and BH-torus phases can reproduce the solar abundances amazingly well for A>90. Varying contributions of the torus ejecta might account for observed variations of lighter elements with 40<Z<56 relative to heavier ones, and a considerable reduction of the prompt ejecta compared to the torus ejecta, e.g. in highly asymmetric NS-BH mergers, might explain the composition of heavy-element deficient stars.

We present the first comprehensive study of r-process element nucleosynthesis in the ejecta of compact binary mergers (CBMs) and their relic black-hole (BH)-torus systems. The evolution of the BH-accretion tori is simulated for seconds with a Newtonian hydrodynamics code including viscosity effects, pseudo-Newtonian gravity for rotating BHs, and an energy-dependent two-moment closure scheme for the transport of electron neutrinos and antineutrinos. The investigated cases are guided by relativistic double neutron star (NS-NS) and NS-BH merger models, producing ~3-6 Msun BHs with rotation parameters of A~0.8 and tori of 0.03-0.3 Msun. Our nucleosynthesis analysis includes the dynamical (prompt) ejecta expelled during the CBM phase and the neutrino and viscously driven outflows of the relic BH-torus systems. While typically ~20-25% of the initial accretion-torus mass are lost by viscously driven outflows, neutrino-powered winds contribute at most another ~1%, but neutrino heating enhances the viscous ejecta significantly. Since BH-torus ejecta possess a wide distribution of electron fractions (0.1-0.6) and entropies, they produce heavy elements from A~80 up to the actinides, with relative contributions of A>130 nuclei being subdominant and sensitively dependent on BH and torus masses and the exact treatment of shear viscosity. The combined ejecta of CBM and BH-torus phases can reproduce the solar abundances amazingly well for A>90. Varying contributions of the torus ejecta might account for observed variations of lighter elements with 40<Z<56 relative to heavier ones, and a considerable reduction of the prompt ejecta compared to the torus ejecta, e.g. in highly asymmetric NS-BH mergers, might explain the composition of heavy-element deficient stars.