Abstract
We enhance the treatment of crystallization for models of white dwarfs (WDs) in the stellar evolution software Modules for Experiments in Stellar Astrophysics (MESA) by implementing ...carbon–oxygen (C/O) phase separation. The phase separation process during crystallization leads to transport of oxygen toward the centers of WDs, resulting in a more compact structure that liberates gravitational energy as additional heating that modestly slows WD cooling timescales. We quantify this cooling delay in MESA C/O WD models over the mass range 0.5–1.0
M
⊙
, finding delays of 0.5–0.8 Gyr for typical C/O interior profiles. MESA WD cooling timescales including this effect are generally comparable to other WD evolution models that make similar assumptions about input physics. When considering phase separation alongside
22
Ne sedimentation, however, we find that both MESA and BaSTI WD cooling models predict a more modest sedimentation delay than the latest LPCODE models, and this may therefore require a reevaluation of previously proposed solutions to some WD cooling anomalies that were based on LPCODE models of
22
Ne sedimentation. Our implementation of C/O phase separation in the open-source stellar evolution software MESA provides an important tool for building realistic grids of WD cooling models, as well as a framework for expanding on our implementation to explore additional physical processes related to phase transitions and associated fluid motions in WD interiors.
We update the capabilities of the software instrument Modules for Experiments in Stellar Astrophysics (MESA) and enhance its ease of use and availability. Our new approach to locating convective ...boundaries is consistent with the physics of convection, and yields reliable values of the convective-core mass during both hydrogen- and helium-burning phases. Stars with become white dwarfs and cool to the point where the electrons are degenerate and the ions are strongly coupled, a realm now available to study with MESA due to improved treatments of element diffusion, latent heat release, and blending of equations of state. Studies of the final fates of massive stars are extended in MESA by our addition of an approximate Riemann solver that captures shocks and conserves energy to high accuracy during dynamic epochs. We also introduce a 1D capability for modeling the effects of Rayleigh-Taylor instabilities that, in combination with the coupling to a public version of the radiation transfer instrument, creates new avenues for exploring Type II supernova properties. These capabilities are exhibited with exploratory models of pair-instability supernovae, pulsational pair-instability supernovae, and the formation of stellar-mass black holes. The applicability of MESA is now widened by the capability to import multidimensional hydrodynamic models into MESA. We close by introducing software modules for handling floating point exceptions and stellar model optimization, as well as four new software tools- , -Docker, , and mesastar.org-to enhance MESA's education and research impact.
Summary
Background
The pathogenesis of the chronic inflammatory skin disease hidradenitis suppurativa (HS, also known as acne inversa) involves epidermal alterations such as psoriasiform epidermal ...hyperplasia and keratin plugging. Keratinocytes are an important source of proinflammatory molecules in inflammatory skin diseases and can be stimulated by interleukin (IL)‐17+ cells.
Objectives
To explore the possible role of the epithelium in the pathogenesis of HS.
Methods
We performed immunohistochemical stainings and Western blot experiments to investigate the localization and expression of inflammation‐associated molecules, including the cytokine IL‐17, components of the inflammasome including caspase‐1, and the endogenous danger‐associated molecular pattern molecules S100A8 and S100A9 (calprotectin). To examine a possible effect of upregulated proinflammatory cytokines on the inflammatory infiltrate, differences in the cellular composition of perifollicular and deep dermal infiltrates were analysed.
Results
The number of IL‐17+ cells is increased in lesional and perilesional HS skin. The epidermis produces proinflammatory molecules and shows an upregulated expression of components of the NLRP3 inflammasome, activated caspase‐1 and expression of S100A8/S100A9. Additionally, the course of the inflammatory process in HS involves influx of innate immune cells, particularly IL‐17‐expressing neutrophils.
Conclusions
IL‐17‐producing cells are present in lesional and perilesional HS skin and may contribute to the initiation of inflammatory processes. Furthermore, the epidermis is a source of proinflammatory cytokines, shows inflammasome activation and expresses S100A8/S100A9, thereby possibly contributing to the propagation of inflammation. A massive influx of IL‐17‐expressing neutrophils is observed in the deep infiltrate.
What's already known about this topic?
The proinflammatory cytokines interleukin (IL)‐17 and IL‐1β are upregulated in lesional skin of patients with hidradenitis suppurativa (HS).
The endogenous danger‐associated molecular pattern molecules S100A8 and S100A9 are elevated in the serum of patients with HS.
What does this study add?
IL‐17+ cells are present in perilesional skin of patients with HS.
NLRP3 expression is enhanced and the inflammasome is activated in lesional epidermis of HS.
S100A8 and S100A9 are upregulated in lesional HS epidermis.
Infiltrating neutrophils are a source of IL‐17, thereby sustaining the inflammatory process.
Linked Comment: Marzano. Br J Dermatol 2016; 174:482–483.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Abstract
We update the capabilities of the open-knowledge software instrument Modules for Experiments in Stellar Astrophysics (
MESA
). The new
auto
_
diff
module implements automatic differentiation ...in
MESA
, an enabling capability that alleviates the need for hard-coded analytic expressions or finite-difference approximations. We significantly enhance the treatment of the growth and decay of convection in
MESA
with a new model for time-dependent convection, which is particularly important during late-stage nuclear burning in massive stars and electron-degenerate ignition events. We strengthen
MESA
’s implementation of the equation of state, and we quantify continued improvements to energy accounting and solver accuracy through a discussion of different energy equation features and enhancements. To improve the modeling of stars in
MESA
, we describe key updates to the treatment of stellar atmospheres, molecular opacities, Compton opacities, conductive opacities, element diffusion coefficients, and nuclear reaction rates. We introduce treatments of starspots, an important consideration for low-mass stars, and modifications for superadiabatic convection in radiation-dominated regions. We describe new approaches for increasing the efficiency of calculating monochromatic opacities and radiative levitation, and for increasing the efficiency of evolving the late stages of massive stars with a new operator-split nuclear burning mode. We close by discussing major updates to
MESA
’s software infrastructure that enhance source code development and community engagement.
Abstract
The polluted white dwarf (WD) system SDSS J122859.93+104032.9 (SDSS J1228) shows variable emission features interpreted as originating from a solid core fragment held together against tidal ...forces by its own internal strength, orbiting within its surrounding debris disk. Estimating the size of this orbiting solid body requires modeling the accretion rate of the polluting material that is observed mixing into the WD surface. That material is supplied via sublimation from the surface of the orbiting solid body. The sublimation rate can be estimated as a simple function of the surface area of the solid body and the incident flux from the nearby hot WD. On the other hand, estimating the accretion rate requires detailed modeling of the surface structure and mixing in the accreting WD. In this work, we present MESA WD models for SDSS J1228 that account for the thermohaline instability and mixing in addition to heavy element sedimentation to constrain accurately the sublimation and accretion rate necessary to supply the observed pollution. We derive a total accretion rate of
M
̇
acc
=
1.8
×
10
11
g
s
−
1
, several orders of magnitude higher than the
M
̇
acc
=
5.6
×
10
8
g
s
−
1
estimate obtained in earlier efforts. The larger mass accretion rate implies that the minimum estimated radius of the orbiting solid body is
r
min
= 72 km, which, although significantly larger than prior estimates, still lies within the upper bounds (a few hundred kilometers) for which the internal strength could no longer withstand the tidal forces from the gravity of the WD.
Purpose The impact of the original International Children's Continence Society terminology document on lower urinary tract function resulted in the global establishment of uniformity and clarity in ...the characterization of lower urinary tract function and dysfunction in children across multiple health care disciplines. The present document serves as a stand-alone terminology update reflecting refinement and current advancement of knowledge on pediatric lower urinary tract function. Materials and Methods A variety of worldwide experts from multiple disciplines in the ICCS leadership who care for children with lower urinary tract dysfunction were assembled as part of the standardization committee. A critical review of the previous ICCS terminology document and the current literature was performed. In addition, contributions and feedback from the multidisciplinary ICCS membership were solicited. Results Following a review of the literature during the last 7 years the ICCS experts assembled a new terminology document reflecting the current understanding of bladder function and lower urinary tract dysfunction in children using resources from the literature review, expert opinion and ICCS member feedback. Conclusions The present ICCS terminology document provides a current and consensus update to the evolving terminology and understanding of lower urinary tract function in children. For the complete document visit http://jurology.com/.
Abstract
Regular, automated testing is a foundational principle of modern software development. Numerous widely used continuous integration systems exist, but they are often not suitable for the ...unique needs of scientific simulation software. Here we describe the testing infrastructure developed for and used by the Modules for Experiments in Stellar Astrophysics (MESA) project. This system allows the computationally demanding MESA test suite to be regularly run on a heterogeneous set of computers and aggregates and displays the testing results in a form that allows for the rapid identification and diagnosis of regressions. Regularly collecting comprehensive testing data also enables longitudinal studies of the performance of the software and the properties of the models it generates.
Topological phases in frustrated quantum spin systems have fascinated researchers for decades. One of the earliest proposals for such a phase was the chiral spin liquid, a bosonic analogue of the ...fractional quantum Hall effect, put forward by Kalmeyer and Laughlin in 1987. Elusive for many years, recent times have finally seen this phase realized in various models, which, however, remain somewhat artificial. Here we take an important step towards the goal of finding a chiral spin liquid in nature by examining a physically motivated model for a Mott insulator on the Kagome lattice with broken time-reversal symmetry. We discuss the emergent phase from a network model perspective and present an unambiguous numerical identification and characterization of its universal topological properties, including ground-state degeneracy, edge physics and anyonic bulk excitations, by using a variety of powerful numerical probes, including the entanglement spectrum and modular transformations.
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