Self-consistent picture of the mass ejection from a one second-long binary neutron star merger leaving a short-lived remnant in general-relativistic neutrino-radiation magnetohydrodynamic simulation

We perform a general-relativistic neutrino-radiation magnetohydrodynamicsimulation of a one second-long binary neutron star merger on Japanesesupercomputer Fugaku using about $72$ million CPU hours with $20,736$ CPUs. Weconsider an asymmetric binary neutron star merger with masses of $1.2$ and$1.5M_\odot$ and a `soft' equation of state SFHo. It results in a short-livedremnant with the lifetime of $\approx 0.017$\,s, and subsequent massive torusformation with the mass of $\approx 0.05M_\odot$ after the remnant collapses toa black hole. For the first time, we confirm that after the dynamical massejection, which drives the fast tail and mildly relativistic components, thepost-merger mass ejection from the massive torus takes place due to themagnetorotational instability-driven turbulent viscosity and the two ejectacomponents are seen in the distributions of the electron fraction and velocitywith distinct features.<br

General-relativistic neutrino-radiation magnetohydrodynamics simulation of black hole-neutron star mergers for seconds

Seconds-long numerical-relativity simulations for black hole-neutron star mergers are performed for the first time to obtain a self-consistent picture of the merger and post-merger evolution processes. To investigate the case that tidal disruption takes place, we choose the initial mass of the black hole to be $5.4M_\odot$ or $8.1M_\odot$ with the dimensionless spin of 0.75. The neutron-star mass is fixed to be $1.35M_\odot$. We find that after the tidal disruption, dynamical mass ejection takes place spending $\lesssim 10\,{\rm ms}$ together with the formation of a massive accretion disk. Subsequently, the magnetic field in the disk is amplified by the magnetic winding and magnetorotational instability, establishing a turbulent state and inducing the angular momentum transport. The post-merger mass ejection by the magnetically-induced viscous effect sets in at $\sim 300$-$500\,{\rm ms}$ after the tidal disruption, at which the neutrino luminosity drops below $\sim 10^{51.5}\,{\rm erg/s}$, and continues for several hundreds ms. A magnetosphere near the rotational axis of the black hole is developed after the matter and magnetic flux fall into the black hole from the accretion disk, and high-intensity Poynting flux generation sets in at a few hundreds ms after the tidal disruption. The intensity of the Poynting flux becomes low after the significant post-merger mass ejection, because the opening angle of the magnetosphere increases. The lifetime for the stage with the strong Poynting flux is $1$-$2\,{\rm s}$, which agrees with the typical duration of short-hard gamma-ray bursts

General-relativistic neutrino-radiation magnetohydrodynamics simulation of seconds-long black hole-neutron star mergers: Dependence on initial magnetic field strength, configuration, and neutron-star equation of state

Numerical-relativity simulations for seconds-long black hole-neutron starmergers are performed to obtain a self-consistent picture starting from theinspiral and the merger throughout the post-merger stages for a variety ofsetups. Irrespective of the initial and computational setups, we findqualitatively universal evolution processes: The dynamical mass ejection takesplace together with a massive accretion disk formation after the neutron staris tidally disrupted; Subsequently, the magnetic field in the accretion disk isamplified by the magnetic winding, Kelvin-Helmholtz instability, andmagnetorotational instability, which establish a turbulent state inducing thedynamo and angular momentum transport; The post-merger mass ejection by theeffective viscous effects stemming from the magnetohydrodynamics turbulencesets in at $\sim300$-$500$ ms after the merger and continues for severalhundred ms; A magnetosphere near the black-hole spin axis is developed and thecollimated strong Poynting flux is generated with its lifetime of $\sim0.5$-$2$s. The model of no equatorial-plane symmetry shows the reverse of themagnetic-field polarity in the magnetosphere, which is caused by the dynamoassociated with the magnetorotational instability in the accretion disk. Themodel with initially toroidal fields shows the tilt of the disk andmagnetosphere in the late post-merger stage because of the anisotropicpost-merger mass ejection. These effects could terminate the strongPoynting-luminosity stage within the timescale of $\sim0.5$-$2$ s.<br

Constraint propagation equations of the 3+1 decomposition of f(R) gravity

Theories of gravity other than general relativity (GR) can explain the observed cosmic acceleration without a cosmological constant. One such class of theories of gravity is f(R). Metric f(R) theories have been proven to be equivalent to Brans-Dicke (BD) scalar-tensor gravity without a kinetic term. Using this equivalence and a 3+1 decomposition of the theory it has been shown that metric f(R) gravity admits a well-posed initial value problem. However, it has not been proven that the 3+1 evolution equations of metric f(R) gravity preserve the (hamiltonian and momentum) constraints. In this paper we show that this is indeed the case. In addition, we show that the mathematical form of the constraint propagation equations in BD-equilavent f(R) gravity and in f(R) gravity in both the Jordan and Einstein frames, is exactly the same as in the standard ADM 3+1 decomposition of GR. Finally, we point out that current numerical relativity codes can incorporate the 3+1 evolution equations of metric f(R) gravity by modifying the stress-energy tensor and adding an additional scalar field evolution equation. We hope that this work will serve as a starting point for relativists to develop fully dynamical codes for valid f(R) models.Comment: 25 pages, matches published version in CQG, references update

Fibrotic Myofibroblasts Manifest Genome-Wide Derangements of Translational Control

Background: As a group, fibroproliferative disorders of the lung, liver, kidney, heart, vasculature and integument are common, progressive and refractory to therapy. They can emerge following toxic insults, but are frequently idiopathic. Their enigmatic propensity to resist therapy and progress to organ failure has focused attention on the myofibroblast–the primary effector of the fibroproliferative response. We have recently shown that aberrant beta 1 integrin signaling in fibrotic fibroblasts results in defective PTEN function, unrestrained Akt signaling and subsequent activation of the translation initiation machinery. How this pathological integrin signaling alters the gene expression pathway has not been elucidated. Results: Using a systems approach to study this question in a prototype fibrotic disease, Idiopathic Pulmonary Fibrosis (IPF); here we show organized changes in the gene expression pathway of primary lung myofibroblasts that persist for up to 9 sub-cultivations in vitro. When comparing IPF and control myofibroblasts in a 3-dimensional type I collagen matrix, more genes differed at the level of ribosome recruitment than at the level of transcript abundance, indicating pathological translational control as a major characteristic of IPF myofibroblasts. To determine the effect of matrix state on translational control, myofibroblasts were permitted to contract the matrix. Ribosome recruitment in control myofibroblasts was relatively stable. In contrast, IPF cells manifested large alterations in the ribosome recruitment pattern. Pathological studies suggest an epithelial origin for IPF myofibroblasts through the epithelial to mesenchymal transition (EMT). In accord wit

Mass ejection from disks surrounding a low-mass black hole: Viscous neutrino-radiation hydrodynamics simulation in full general relativity

New viscous neutrino-radiation hydrodynamics simulations are performed for accretion disks surrounding a spinning black hole with low mass $3M_\odot$ and dimensionless spin 0.8 or 0.6 in full general relativity, aiming at modeling the evolution of a merger remnant of massive binary neutron stars or low-mass black hole-neutron star binaries. We reconfirm the following results found by previous studies of other groups: 15-30% of the disk mass is ejected from the system with the average velocity of $\sim$5-10% of the speed of light for the plausible profile of the disk as merger remnants. In addition, we find that for the not extremely high viscous coefficient case, the neutron richness of the ejecta does not become very high, because weak interaction processes enhance the electron fraction during the viscous expansion of the disk before the onset of the mass ejection, resulting in the suppression of the lanthanide synthesis. For high-mass disks, the viscous expansion timescale is increased by a longer-term neutrino emission, and hence, the electron fraction of the ejecta becomes even higher. We also confirm that the mass distribution of the electron fraction depends strongly on the magnitude of the given viscous coefficient. This demonstrates that a first-principle magnetohydrodynamics simulation is necessary for black hole-disk systems with sufficient grid resolution and with sufficiently long timescale (longer than seconds) to clarify the nucleosynthesis and electromagnetic signals from them

Effect of Escherichia coli and Staphylococcus aureus on the In vitro Response of Peripheral Blood Mononuclear Cells Isolated from Holstein Dairy Cows had Ketosis or Milk Fever of Field Cases

The expression of cytokines mRNA, including Interleukin (IL)-2, IL-4 and Interferon (IFN)-γ and lymphocyte proliferation stimulated in vitro with either Escherichia coli (E. coli) or Staphylococcus aureus (S.A.) by Peripheral Blood Mononuclear Cells (PBMC) obtained from Holstein dairy cows were examined after the onset of ketosis or milk fever of field cases during the lactation period. The cows were used 50 to 150 days after calving in this study and divided into three groups; seventeen cows with milk fever (MF Group, 94.9±8.6 days after calving), ten cows with ketosis (Ketosis Group, 96.3±10.2 days after calving) and twenty-seven cows with no clinical diseases (Control Group, 89.4±5.4 days after calving). PBMC were stimulated in vitro by soluble antigen of E. coli or S.A. together with recombinant IL-2. The numbers of the peripheral blood T cells and monocyte were lower in the Ketosis Group in comparison with those in the Control Group and a significant difference was found in the number of CD3^+TcR1-N12^+T cells. There was a significantly lower lymphocyte proliferation stimulated with E. coli and S.A. in the Ketosis Group compared to that in the Control Group. Expression of IL-2, IL-4 and IFN-γ mRNA in PBMC stimulated with S.A. in the Ketosis Group was significantly lower than that in the Control Group, but these cytokine expression showed no group differences when PBMC were stimulated with E. coli. The present study demonstrated the onset of ketosis during the lactation period decreases reactivity of PBMC at least when they were stimulated with S.A in vitro