Understanding the Mass-Radius Relation for Sub-Neptunes: Radius as a Proxy for Composition

Transiting planet surveys like Kepler have provided a wealth of information on the distribution of planetary radii, particularly for the new populations of super-Earth and sub-Neptune sized planets. In order to aid in the physical interpretation of these radii, we compute model radii for low-mass rocky planets with hydrogen-helium envelopes. We provide model radii for planets 1-20 Earth masses, with envelope fractions from 0.01-20%, levels of irradiation 0.1-1000x Earth's, and ages from 100 Myr to 10 Gyr. In addition we provide simple analytic fits that summarize how radius depends on each of these parameters. Most importantly, we show that at fixed composition, radii show little dependence on mass for planets with more than ~1% of their mass in their envelope. Consequently, planetary radius is to first order a proxy for planetary composition for Neptune and sub-Neptune sized planets. We recast the observed mass-radius relationship as a mass-composition relationship and discuss it in light of traditional core accretion theory. We discuss the transition from rocky super-Earths to sub-Neptune planets with large volatile envelopes. We suggest 1.75 Earth radii as a physically motivated dividing line between these two populations of planets. Finally, we discuss these results in light of the observed radius occurrence distribution found by Kepler.Comment: 17 pages, 9 figures, 7 tables, submitted to Ap

Re-inflated Warm Jupiters Around Red Giants

Since the discovery of the first transiting hot Jupiters, models have sought to explain the anomalously large radii of highly irradiated gas giants. We now know that the size of hot Jupiter radius anomalies scales strongly with a planet's level of irradiation and numerous models like tidal heating, ohmic dissipation, and thermal tides have since been developed to help explain these inflated radii. In general however, these models can be grouped into two broad categories: 1) models that directly inflate planetary radii by depositing a fraction of the incident irradiation into the interior and 2) models that simply slow a planet's radiative cooling allowing it to retain more heat from formation and thereby delay contraction. Here we present a new test to distinguish between these two classes of models. Gas giants orbiting at moderate orbital periods around post main sequence stars will experience enormous increases their irradiation as their host stars move up the sub-giant and red-giant branches. If hot Jupiter inflation works by depositing irradiation into the planet's deep interiors then planetary radii should increase in response to the increased irradiation. This means that otherwise non-inflated gas giants at moderate orbital periods >10 days can re-inflate as their host stars evolve. Here we explore the circumstances that can lead to the creation of these "re-inflated" gas giants and examine how the existence or absence of such planets can be used to place unique constraints of the physics of the hot Jupiter inflation mechanism. Finally, we explore the prospects for detecting this potentially important undiscovered population of planets.Comment: Accepted by ApJ. 8 Figures and 8 page

Mindfulness meditation and improvement in depressive symptoms among Spanish- and English speaking adults: A randomized, controlled, comparative efficacy trial.

ObjectiveLatino immigrants experience acculturative stress and increased depression risk. Mindfulness meditation improves depressive symptoms, yet the vast majority of research has focused on English speaking populations.MethodsIn this randomized clinical trial with 2 parallel treatment groups, adults with moderate levels of perceived stress (n = 76) were recruited from the Los Angeles community from October 2015 to March 2016, stratified into Spanish- (n = 36) and English speaking (n = 40) language groups, and randomized for 6 weeks of treatment with standardized mindful awareness practices (MAPs) or health education (HE). Main outcome measure was depressive symptoms, measured by the Beck Depression Inventory.ResultsUsing an intent-to-treat analysis, the primary outcome, depressive symptoms as indexed by the Beck Depression Inventory, showed greater improvement in MAPs vs. HE, with a between-group post-intervention mean difference of -2.2 (95% CI -4.4 - -0.07) and effect size of 0.28; similar effect sizes were found in the the Spanish- (0.29) and English speaking (0.30) groups. MAPs showed significant improvement relative to HE on secondary outcome of mindfulness with between group difference of 10.7 (95% CI4.5-16.9), but not perceived stress.ConclusionThe comparable efficacy of Spanish and English formats of mindfulness meditation in improving depressive symptoms suggests that this community based intervention may mitigate depression risk in Latino adults who are experiencing social adversity.Trial registrationClinicalTrials.gov NCT03545074

Reform, Revolution and Confessionalization Some Social Effects of the Reformation on Church & Society in the Holy Roman Empire

In literature about the Reformation it is not always clear what effects Reformation ideas had beyond their theological significance. Recent research on the Reformation and Post-Reformation periods is providing some helpful insights as to how these theological ideas were implemented and led to concrete social effects. This investigation draws on that research in an attempt to track how several of the ideas of the initial reformers had lasting social effects and what some of those effects were. As part of this historical-theological analysis it will be shown how confessionalization was as effect of the Reformation but was also a courier and solidifying agent of many of the other social effects

Maximus the Confessor & the Trinity - The Early Works

In this study, I will argue that Maximus the Confessor’s (580-662 CE) engagement with the ascetic concerns and the theological controversies of the sixth and seventh century helped develop his early works toward a unique and distinctively Trinitarian articulation of Christian life and post-Chalcedonian theology. In the Liber asceticus, Maximus illustrates the Trinity as the beginning, means and end of Christian life, highlighting baptism, the Spirit’s appropriation of Son’s activities to the baptized, how the incarnate Son serves as the example of love and interweaves Trinitarian prayer into the dialogue’s appeal for mercy. Using the Liber as a baseline (Ch. 1), Chapter 2 places his Trinitarian grammar for Christian life in its ascetic context demonstrating areas of continuity but also its unique contribution. The subsequent chapters then track this grammar’s development by analyzing the increased complexity, sparked by his engagement with various concerns and controversies, displayed in Capita caritate (Ch. 3), Quaestiones et dubia and Epistula 2 (Ch.4). The last section of Ch.4 provides a context for his engagement of pro-Chalcedonian theology and its development in Opusculum 13. In the Capita, Maximus’ engagement with Origenism underscores the irreducible difference between God and creation yet also how they are sustained, preserved and deified through participation. His engagement with demonstrates the necessity of joining θεωρία and πρᾶξις, giving an early glimpse of union and distinction in his Trinitarian theology. Finally, what was only illustrated in the Liber, is made explicit through a robust explanation of contemplation and prayer. In Quaestiones, Maximus begins to fix his terminology for the stages of ascent. Additionally, while continuing to engage with Origenism, he introduces more technical language for the incarnation, utilizes the Logos/λόγοι doctrine for ascent and applies the λόγος/τρόπος distinction for the Trinity. Then, in Ep. 2, he integrates these new features from Quaestiones into his description of ascent and the incarnation. Finally, in Op. 13, Maximus departs from his earlier concern for ascent yet, like his other early works, reveals engagement with a specific controversy – miaphysitism

Dynamics of swimming bacteria at complex interfaces

Flagellated bacteria exploiting helical propulsion are known to swim along circular trajectories near surfaces. Fluid dynamics predicts this circular motion to be clockwise (CW) above a rigid surface (when viewed from inside the fluid) and counter-clockwise (CCW) below a free surface. Recent experimental investigations showed that complex physicochemical processes at the nearby surface could lead to a change in the direction of rotation, both at solid surfaces absorbing slip-inducing polymers and interfaces covered with surfactants. Motivated by these results, we use a far-field hydrodynamic model to predict the kinematics of swimming near three types of interfaces: clean fluid-fluid interface, slipping rigid wall, and a fluid interface covered by incompressible surfactants. Representing the helical swimmer by a superposition of hydrodynamic singularities, we first show that in all cases the surfaces reorient the swimmer parallel to the surface and attract it, both of which are a consequence of the Stokes dipole component of the swimmer flow field. We then show that circular motion is induced by a higher-order singularity, namely a rotlet dipole, and that its rotation direction (CW vs. CCW) is strongly affected by the boundary conditions at the interface and the bacteria shape. Our results suggest thus that the hydrodynamics of complex interfaces provide a mechanism to selectively stir bacteria