Many of the currently available equations of state for core-collapse supernova simulations give large neutron star radii and do not provide large enough neutron star masses, both of which are ...inconsistent with some recent neutron star observations. In addition, one of the critical uncertainties in the nucleon-nucleon interaction, the nuclear symmetry energy, is not fully explored by the currently available equations of state. In this article, we construct two new equations of state which match recent neutron star observations and provide more flexibility in studying the dependence on nuclear matter properties. The equations of state are also provided in tabular form, covering a wide range in density, temperature, and asymmetry, suitable for astrophysical simulations. These new equations of state are implemented into our spherically symmetric core-collapse supernova model, which is based on general relativistic radiation hydrodynamics with three-flavor Boltzmann neutrino transport. The results are compared with commonly used equations of state in supernova simulations of 11.2 and 40 M sub(middot in circle) progenitors. We consider only equations of state which are fitted to nuclear binding energies and other experimental and observational constraints. We find that central densities at bounce are weakly correlated with L and that there is a moderate influence of the symmetry energy on the evolution of the electron fraction. The new models also obey the previously observed correlation between the time to black hole formation and the maximum mass of an s = 4 neutron star.
•Investigation of creep-fatigue behavior of X20CrMoV12-1 from 300 °C to 600 °C in dependence of atmosphere.•Validation of the K-concept for application of damage tolerance concepts in flexibly ...operated power plants with consideration of the microstructural peculiarities of ferritic-martensitic steels.•Investigation of steam oxidation impact on the transition from fatigue to creep-fatigue interaction.•Analysis of the impact of different evaluation concepts on results and subsequent interpretation.•Detailed microstructural investigation of the cracking mechanisms.
In this study the impact of frequency or rather hold time and atmosphere on the transition from fatigue dominated crack growth to creep fatigue of the ferritic/martensitic steel X20CrMoV12-1 was investigated from 300 °C−600 °C. This temperature range is most important for power plants operated in a flexible manner. Due to the increased share of renewable sources of energy, modern thermal power plants must be operated in a flexible manner to compensate fluctuating power supply from renewables. More damaging loading scenarios, including frequent start-up and shut-down cycles as well as load fluctuations, occur much more frequently than in the past as a consequence. Fatigue damage becomes more and more important, while creep damage reduces due to shorter full power operation durations. Furthermore, loss of passivation by fatigue induced cracking and delamination of protective oxide layers may constitute strong interdependencies of increased cyclic operation and steam oxidation resistance. This results in the necessity for a innovative surveillance concepts including operation mode dependent inspection intervals of thermal power plants. Application of a damage tolerance concept, based on fracture mechanics, can help to improve remaining life assessment of existing and fatigue tolerant design of future power plants. In order to develop codes for flexibly operated components, based on damage tolerance analysis by linear elastic fracture mechanics, its validity range and especially its limitation have to be evaluated first. The study has shown that the transition from pure fatigue to creep fatigue interaction begins at 500 °C and 3.33 × 10−3 Hz (300 s hold time). Furthermore this transition was found to be independent from steam atmosphere. The corresponding fracture mechanisms were investigated in detail.
Active galactic nuclei (AGNs) are axisymmetric systems to first order; their observed properties are likely strong functions of inclination with respect to our line of sight (LOS). However, except ...for a few special cases, the specific inclinations of individual AGNs are unknown. We have developed a promising technique for determining the inclinations of nearby AGNs by mapping the kinematics of their narrow-line regions (NLRs), which are often easily resolved with Hubble Space Telescope OIII imaging and long-slit spectra from the Space Telescope Imaging Spectrograph. Our studies indicate that NLR kinematics dominated by radial outflow can be fit with simple biconical outflow models that can be used to determine the inclination of the bicone axis, and hence the obscuring torus, with respect to our LOS. We present NLR analysis of 53 Seyfert galaxies and the resulting inclinations from models of 17 individual AGNs with clear signatures of biconical outflows. Our model results agree with the unified model in that Seyfert 1 AGNs have NLRs inclined further toward our LOS than Seyfert 2 AGNs. Knowing the inclinations of these AGN NLRs, and thus their accretion disk and/or torus axes, will allow us to determine how their observed properties vary as a function of polar angle. We find no correlation between the inclinations of the AGN NLRs and the disks of their host galaxies, indicating that the orientation of the gas in the torus is independent of that of the host disk.
Abstract
We present the first spatially resolved mass outflow rate measurements (
) of the optical emission line gas in the narrow line region (NLR) of a Seyfert 2 galaxy, Markarian 573. Using long ...slit spectra and O
iii
imaging from the
Hubble Space Telescope
and
Apache Point Observatory
in conjunction with emission line diagnostics and Cloudy photoionization models, we find a peak outflow rate of
at a distance of 210 pc from the central supermassive black hole (SMBH). The outflow extends to distances of 600 pc from the nucleus with a total mass and kinetic energy of
M
≈ 2.2 × 10
6
M
⊙
and
E
≈ 5.1 × 10
54
erg, revealing the outflows to be more energetic than those in the lower luminosity Seyfert 1 galaxy NGC 4151. The peak outflow rate is an order of magnitude larger than the mass accretion and nuclear outflow rates, indicating local in situ acceleration of the circumnuclear NLR gas. We compare these results to global techniques that quantify an average outflow rate across the NLR, and find the latter are subject to larger uncertainties. These results indicate that spatially resolved observations are critical for probing AGN feedback on scales where circumnuclear star formation occurs.
Massive stars end their lives in explosions with kinetic energies on the order of 1051 erg. Immediately after the explosion has been launched, a region of low density and high entropy forms behind ...the ejecta, which is continuously subject to neutrino heating. The neutrinos emitted from the remnant at the center, the protoneutron star (PNS), heat the material above the PNS surface. This heat is partly converted into kinetic energy, and the material accelerates to an outflow that is known as the neutrino-driven wind. For the first time we simulate the collapse, bounce, explosion, and the neutrino-driven wind phases consistently over more than 20 s. Our numerical model is based on spherically symmetric general relativistic radiation hydrodynamics using spectral three-flavor Boltzmann neutrino transport. In simulations where no explosions are obtained naturally, we model neutrino-driven explosions for low- and intermediate-mass Fe-core progenitor stars by enhancing the charged current reaction rates. In the case of a special progenitor star, the 8.8 $M_\odot$ O-Ne-Mg-core, the explosion in spherical symmetry was obtained without enhanced opacities. The post-explosion evolution is in qualitative agreement with static steady-state and parametrized dynamic models of the neutrino-driven wind. On the other hand, we generally find lower neutrino luminosities and mean neutrino energies, as well as a different evolutionary behavior of the neutrino luminosities and mean neutrino energies. The neutrino-driven wind is proton-rich for more than 10 s and the contraction of the PNS differs from the assumptions made for the conditions at the inner boundary in previous neutrino-driven wind studies. Despite the moderately high entropies of about 100 kB/baryon and the fast expansion timescales, the conditions found in our models are unlikely to favor r-process nucleosynthesis. The simulations are carried out until the neutrino-driven wind settles down to a quasi-stationary state. About 5 s after the bounce, the peak temperature inside the PNS already starts to decrease because of the continued deleptonization. This moment determines the beginning of a cooling phase dominated by the emission of neutrinos. We discuss the physical conditions of the quasi-static PNS evolution and take the effects of deleptonization and mass accretion from early fallback into account.
Summary
Background
Increased skin‐surface pH is an important host‐related factor for deteriorated barrier function in aged skin.
Objectives
We investigated whether restoration of skin pH through ...topical application of a water‐in‐oil emulsion with pH 4 improved the barrier homeostasis in aged skin, and compared the effects with an identical galenic formulation with pH 5·8.
Methods
The effects of the test formulations on barrier recovery were investigated by repeated measurements of transepidermal water loss (TEWL) and skin pH 3 h, 6 h and 24 h after acetone‐induced impairment of barrier function in aged skin. The long‐term effects of the pH 4 and pH 5·8 emulsions were analysed by investigation of the barrier integrity and cohesion, the skin‐surface pH and the skin roughness and scaliness before and after a 4‐week, controlled application of the formulations.
Results
The application of the pH 4 emulsion accelerated barrier recovery in aged skin: 3 h and 6 h after acetone‐induced barrier disruption the differences in the TEWL recovery between the pH 4 treated and acetone control fields were significant. Furthermore, long‐term application of the pH 4 formulation resulted in significantly decreased skin pH, enhanced barrier integrity and reduced skin‐surface roughness and scaliness. At the same time points, the pH 5·8 formulation exerted only minor effects on the barrier function parameters.
Conclusions
Exogenous acidification through topical application of a water‐in‐oil emulsion with pH 4 leads to improvement of the skin barrier function and maintenance of the barrier homeostasis in aged skin.
What's already known about this topic?
Aged skin is associated with increased skin‐surface pH.
Increased skin‐surface pH is associated with impairment of the permeability barrier function and properties.
What does this study add?
Normalization of the increased skin pH through topical application of a water‐in‐oil emulsion with pH 4 accelerates the barrier repair and enhances the barrier integrity and properties in aged skin.
pH‐dependent improvement of the barrier function and properties through topical application of water‐in‐oil emulsions with acidic pH in aged individuals in vivo has not previously been shown
Linked Comment: Proksch. Br J Dermatol 2018; 179:254–255.
Respond to this article
We discuss three new equations of state (EOS) in core-collapse supernova simulations. The new EOS are based on the nuclear statistical equilibrium model of Hempel and Schaffner-Bielich (HS), which ...includes excluded volume effects and relativistic mean-field (RMF) interactions. We consider the RMF parameterizations TM1, TMA, and FSUgold. These EOS are implemented into our spherically symmetric core-collapse supernova model, which is based on general relativistic radiation hydrodynamics and three-flavor Boltzmann neutrino transport. The results obtained for the new EOS are compared with the widely used EOS of H. Shen et al. and Lattimer & Swesty. The systematic comparison shows that the model description of inhomogeneous nuclear matter is as important as the parameterization of the nuclear interactions for the supernova dynamics and the neutrino signal. Furthermore, several new aspects of nuclear physics are investigated: the HS EOS contains distributions of nuclei, including nuclear shell effects. The appearance of light nuclei, e.g., deuterium and tritium, is also explored, which can become as abundant as alphas and free protons. In addition, we investigate the black hole formation in failed core-collapse supernovae, which is mainly determined by the high-density EOS. We find that temperature effects lead to a systematically faster collapse for the non-relativistic LS EOS in comparison with the RMF EOS. We deduce a new correlation for the time until black hole formation, which allows the determination of the maximum mass of proto-neutron stars, if the neutrino signal from such a failed supernova would be measured in the future. This would give a constraint for the nuclear EOS at finite entropy, complementary to observations of cold neutron stars.
Multiple sclerosis is a chronic inflammatory disease of the central nervous system, associated with demyelination and neurodegeneration. The mechanisms of tissue injury are poorly understood, but ...recent data suggest that mitochondrial injury may play an important role in this process. Mitochondrial injury can be triggered by reactive oxygen and nitric oxide species, and we recently provided evidence for oxidative damage of oligodendrocytes and dystrophic axons in early stages of active multiple sclerosis lesions. In this study, we identified potential sources of reactive oxygen and nitrogen species through gene expression in carefully staged and dissected lesion areas and by immunohistochemical analysis of protein expression. Genome-wide microarrays confirmed mitochondrial injury in active multiple sclerosis lesions, which may serve as an important source of reactive oxygen species. In addition, we found differences in the gene expression levels of various nicotinamide adenine dinucleotide phosphate oxidase subunits between initial multiple sclerosis lesions and control white matter. These results were confirmed at the protein level by means of immunohistochemistry, showing upregulation of the subunits gp91phox, p22phox, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 in activated microglia in classical active as well as slowly expanding lesions. The subunits gp91phox and p22phox were constitutively expressed in microglia and were upregulated in the initial lesion. In contrast, p47phox, nicotinamide adenine dinucleotide phosphate oxidase 1 and nicotinamide adenine dinucleotide phosphate oxidase organizer 1 expression were more restricted to the zone of initial damage or to lesions from patients with acute or early relapsing/remitting multiple sclerosis. Double labelling showed co-expression of the nicotinamide adenine dinucleotide phosphate oxidase subunits in activated microglia and infiltrated macrophages, suggesting the assembly of functional complexes. Our data suggest that the inflammation-associated oxidative burst in activated microglia and macrophages plays an important role in demyelination and free radical-mediated tissue injury in the pathogenesis of multiple sclerosis.
PDF
