Thermal evolution and structure models of the transiting super-Earth GJ 1214b

The planet GJ 1214b is the second known super-Earth with a measured mass and radius. Orbiting a quiet M-star, it receives considerably less mass-loss driving X-ray and UV radiation than CoRoT-7b, so that the interior may be quite dissimilar in composition, including the possibility of a large fraction of water. We model the interior of GJ 1214b assuming a two-layer (envelope+rock core) structure where the envelope material is either H/He, pure water, or a mixture of H/He and H2O. Within this framework we perform models of the thermal evolution and contraction of the planet. We discuss possible compositions that are consistent with Mp=6.55 ME, Rp=2.678 RE, an age tau=3-10 Gyr, and the irradiation level of the atmosphere. These conditions require that if water exists in the interior, it must remain in a fluid state, with important consequences for magnetic field generation. These conditions also require the atmosphere to have a deep isothermal region extending down to 80-800 bar, depending on composition. Our results bolster the suggestion of a metal-enriched H/He atmosphere for the planet, as we find water-world models that lack an H/He atmosphere to require an implausibly large water-to-rock ratio of more than 6:1. We instead favor a H/He/H2O envelope with high water mass fraction (~0.5-0.85), similar to recent models of the deep envelope of Uranus and Neptune. Even with these high water mass fractions in the H/He envelope, generally the bulk composition of the planet can have subsolar water:rock ratios. Dry, water-enriched, and pure water envelope models differ to an observationally significant level in their tidal Love numbers k2 of respectively ~0.018, 0.15, and 0.7.Comment: 11 pages, 6 figures, 1 table, accepted to Ap

Uranus evolution models with simple thermal boundary layers

The strikingly low luminosity of Uranus (Teff ~ Teq) constitutes a long-standing challenge to our understanding of Ice Giant planets. Here we present the first Uranus structure and evolution models that are constructed to agree with both the observed low luminosity and the gravity field data. Our models make use of modern ab initio equations of state at high pressures for the icy components water, methane, and ammonia. Proceeding step by step, we confirm that adiabatic models yield cooling times that are too long, even when uncertainties in the ice:rock ratio (I:R) are taken into account. We then argue that the transition between the ice/rock-rich interior and the H/He-rich outer envelope should be stably stratified. Therefore, we introduce a simple thermal boundary and adjust it to reproduce the low luminosity. Due to this thermal boundary, the deep interior of the Uranus models are up to 2--3 warmer than adiabatic models, necessitating the presence of rocks in the deep interior with a possible I:R of $1\times$ solar. Finally, we allow for an equilibrium evolution (Teff ~ Teq) that begun prior to the present day, which would therefore no longer require the current era to be a "special time" in Uranus' evolution. In this scenario, the thermal boundary leads to more rapid cooling of the outer envelope. When Teff ~ Teq is reached, a shallow, subadiabatic zone in the atmosphere begins to develop. Its depth is adjusted to meet the luminosity constraint. This work provides a simple foundation for future Ice Giant structure and evolution models, that can be improved by properly treating the heat and particle fluxes in the diffusive zones.Comment: 13 pages, Accepted to Icaru

Placental vascularity and markers of angiogenesis in relation to prenatal growth status in overnourished adolescent ewes.

INTRODUCTION: Placental vascularity may be important in the development of fetal growth restriction (FGR). The overnourished adolescent ewe is a robust model of the condition, with ∼50% of offspring demonstrating FGR (birthweight >2 standard deviations below optimally-fed control mean). We studied whether placental vascularity, angiogenesis and glucose transport reflect FGR severity. METHODS: Singleton pregnancies were established in adolescent ewes either overnourished to putatively restrict fetoplacental growth (n = 27) or control-fed (n = 12). At 131d (term = 145d) pregnancies were interrupted and fetuses classified as FGR (n = 17,  Non-FGR > FGR and fetal:placental weight ratios were higher in overnourished versus Control groups. COT vascular indices were Non-FGR > FGR > Control. COT-CAD, CSD and APC were significantly greater in Non-FGR overnourished versus Control and intermediate in FGR groups. CAR vascularity did not differ. CAR-VEGFA/FLT1/KDR/ANGPT1/ANGPT2/SLC2A1/SLC2A3 mRNA was lower and COT-ANGPT2 higher in overnourished versus Control groups. DISCUSSION: Relative to control-intake pregnancy, overnourished pregnancies are characterised by higher COT vascularity, potentially a compensatory response to reduced nutrient supply, reflected by higher fetal:placental weight ratios. Compared with overnourished pregnancies where fetal growth is relatively preserved, overnourished pregnancies culminating in marked FGR have less placental vascularity, suggesting incomplete adaptation to the prenatal insult

Ab initio equations of state for hydrogen (H-REOS.3) and helium (He-REOS.3) and their implications for the interior of Brown Dwarfs

We present new equations of state (EOS) for hydrogen and helium covering a wide range of temperatures from 60 K to 10$^7$ K and densities from $10^{-10}$ g/cm$^3$ to $10^3$ g/cm$^3$. They include an extended set of ab initio EOS data for the strongly correlated quantum regime with an accurate connection to data derived from other approaches for the neighboring regions. We compare linear-mixing isotherms based on our EOS tables with available real-mixture data. A first important astrophysical application of this new EOS data is the calculation of interior models for Jupiter and the comparison with recent results. Secondly, mass-radius relations are calculated for Brown Dwarfs which we compare with predictions derived from the widely used EOS of Saumon, Chabrier and van Horn. Furthermore, we calculate interior models for typical Brown Dwarfs with different masses, namely Corot-3b, Gliese-229b and Corot-15b, and the Giant Planet KOI-889b. The predictions for the central pressures and densities differ by up to 10$\%$ dependent on the EOS used. Our EOS tables are made available in the supplemental material of this paper.Comment: 14 pages, 19 Figures, accepted at ApJ

Bound States and Superconductivity in Dense Fermi Systems

A quantum field theoretical approach to the thermodynamics of dense Fermi systems is developed for the description of the formation and dissolution of quantum condensates and bound states in dependence of temperature and density. As a model system we study the chiral and superconducting phase transitions in two-flavor quark matter within the NJL model and their interrelation with the formation of quark-antiquark and diquark bound states. The phase diagram of quark matter is evaluated as a function of the diquark coupling strength and a coexistence region of chiral symmetry breaking and color superconductivity is obtained at very strong coupling. The crossover between Bose-Einstein condensation (BEC) of diquark bound states and condensation of diquark resonances (Cooper pairs) in the continuum (BCS) is discussed as a Mott effect. This effect consists in the transition of bound states into the continuum of scattering states under the influence of compression and heating. We explain the physics of the Mott transition with special emphasis on role of the Pauli principle for the case of the pion in quark matter.Comment: 16 pages, 5 figure

Impact Ionization in ZnS

The impact ionization rate and its orientation dependence in k space is calculated for ZnS. The numerical results indicate a strong correlation to the band structure. The use of a q-dependent screening function for the Coulomb interaction between conduction and valence electrons is found to be essential. A simple fit formula is presented for easy calculation of the energy dependent transition rate.Comment: 9 pages LaTeX file, 3 EPS-figures (use psfig.sty), accepted for publication in PRB as brief Report (LaTeX source replaces raw-postscript file

Impact ionization in GaAs: a screened exchange density functional approach

Results are presented of a fully ab-initio calculation of impact ionization rates in GaAs within the density functional theory framework, using a screened-exchange formalism and the highly precise all-electron full-potential linearized augmented plane wave (FLAPW) method. The calculated impact ionization rates show a marked orientation dependence in {\bf k} space, indicating the strong restrictions imposed by the conservation of energy and momentum. This anisotropy diminishes as the impacting electron energy increases. A Keldysh type fit performed on the energy-dependent rate shows a rather soft edge and a threshold energy greater than the direct band gap. The consistency with available Monte Carlo and empirical pseudopotential calculations shows the reliability of our approach and paves the way to ab-initio calculations of pair production rates in new and more complex materials.Comment: 11 pages, 4 figures, Submitted to Phys. Rev.

Association of Rhegmatogenous Retinal Detachment Incidence With Myopia Prevalence in the Netherlands

Importance The incidence of rhegmatogenous retinal detachment (RRD) is partly determined by its risk factors, such as age, sex, cataract surgery, and myopia. Changes in the prevalence of these risk factors could change RRD incidence in the population. Objective To determine whether the incidence of RRD in the Netherlands has changed over recent years and whether this change is associated with an altered prevalence of RRD risk factors. Design, Setting, and Participants This cohort study included data from all 14 vitreoretinal clinics in the Netherlands, as well as a large Dutch population-based cohort study. All patients who underwent surgical repair for a primary RRD in the Netherlands from January 1 to December 31, 2009, and January 1 to December 31, 2016, were analyzed, in addition to all participants in the population-based Rotterdam Study who were examined during these years. Analysis began February 2018 and ended November 2019. Exposures RRD risk factors, including age, male sex, cataract extraction, and myopia. Main Outcomes and Measures Age-specific RRD incidence rate in the Dutch population, as well as change in RRD incidence and risk factor prevalence between 2009 and 2016. Results In 2016, 4447 persons (median [range] age, 61 [3-96] years) underwent surgery for a primary RRD within the Netherlands, resulting in an RRD incidence rate of 26.2 per 100 000 person-years (95% CI, 25.4-27.0). The overall RRD incidence rate had increased by 44% compared with similar data from 2009. The increase was observed in both phakic (1994 in 2009 to 2778 in 2016 [increase, 39%]) and pseudophakic eyes (1004 in 2009 to 1666 in 2016 [increase, 66%]), suggesting that cataract extraction could not solely account for the overall rise. Over the same period, the prevalence of mild, moderate, and severe myopia among persons aged 55 to 75 years had increased by 15.6% (881 of 4561 [19.3%] vs 826 of 3698 [22.3%]), 20.3% (440 of 4561 [9.6%] vs 429 of 3698 [11.6%]), and 26.9% (104 of 4561 [2.3%] vs 107 of 3698 [2.9%]), respectively, within the population-based Rotterdam Study. Conclusions and Relevance In this study, an increase was observed in primary RRD incidence in the Netherlands over a 7-year period, which could not be explained by a different age distribution or cataract surgical rate. A simultaneous myopic shift in the Dutch population may be associated, warranting further population-based studies on RRD incidence and myopia prevalence. This cohort study assesses whether the incidence of rhegmatogenous retinal detachment has changed over recent years and whether this change is associated with an altered prevalence of rhegmatogenous retinal detachment risk factors in the Netherlands. Question What is the incidence of primary rhegmatogenous retinal detachment (RRD) in the Netherlands and has it changed over recent years? Findings In this cohort study, 4447 individuals in the Netherlands underwent surgery for RRD in 2016, resulting in an incidence of 26.2 per 100 000 inhabitants, an increase of 44% compared with similar data from 2009. Over the same period, an increase in myopia prevalence in a Dutch population-based cohort study was observed. Meaning In the Netherlands, an increase in RRD incidence may be associated with a simultaneous myopic shift in the population