Photoevaporation versus core-powered mass-loss: model comparison with the 3D radius gap

The extreme ultraviolet (EUV)/X-ray photoevaporation and core-powered mass-loss models are both capable of reproducing the bimodality in the sizes of small, close-in exoplanets observed by the Kepler space mission, often referred to as the ‘radius gap’. However, it is unclear which of these two mechanisms dominates the atmospheric mass-loss that is likely sculpting the radius gap. In this work, we propose a new method of differentiating between the two models, which relies on analysing the radius gap in 3D parameter space. Using models for both mechanisms, and by performing synthetic transit surveys we predict the size and characteristics of a survey capable of discriminating between the two models. We find that a survey of ≳5000 planets, with a wide range in stellar mass and measurement uncertainties at a ≲5 per cent level is sufficient. Our methodology is robust against moderate false positive contamination of ≲10 per cent⁠. We perform our analysis on two surveys (which do not satisfy our requirements): the California-KeplerSurvey and the Gaia–KeplerSurvey and find, unsurprisingly, that both data sets are consistent with either model. We propose a hypothesis test to be performed on future surveys that can robustly ascertain which of the two mechanisms formed the radius gap, provided one dominates over the other

The UV-SCOPE mission: ultraviolet spectroscopic characterization of planets and their environments

UV-SCOPE is a mission concept to determine the causes of atmospheric mass loss in exoplanets, investigate the mechanisms driving aerosol formation in hot Jupiters, and study the influence of the stellar environment on atmospheric evolution and habitability. As part of these investigations, the mission will generate a broad-purpose legacy database of time-domain ultraviolet (UV) spectra for nearly 200 stars and planets. The observatory consists of a 60 cm, f/10 telescope paired to a long-slit spectrograph, yielding simultaneous, almost continuous coverage between 1203 Å and 4000 Å, with resolutions ranging from 6000 to 240. The efficient instrument provides throughputs < 4% (far-UV; FUV) and < 15% (near-UV; NUV), comparable to HST/COS and much better than HST/STIS, over the same spectral range. A key design feature is the LiF prism, which serves as a dispersive element and provides high throughput even after accounting for radiation degradation. The use of two delta-doped Electron-Multiplying CCD detectors with UV-optimized, single-layer anti-reflection coatings provides high quantum efficiency and low detector noise. From the Earth-Sun second Lagrangian point, UV-SCOPE will continuously observe planetary transits and stellar variability in the full FUV-to-NUV range, with negligible astrophysical background. All these features make UV-SCOPE the ideal instrument to study exoplanetary atmospheres and the impact of host stars on their planets. UV-SCOPE was proposed to NASA as a Medium Explorer (MidEx) mission for the 2021 Announcement of Opportunity. If approved, the observatory will be developed over a 5-year period. Its primary science mission takes 34 months to complete. The spacecraft carries enough fuel for 6 years of operations

Planet Populations as a Function of Stellar Properties

Exoplanets around different types of stars provide a window into the diverse environments in which planets form. This chapter describes the observed relations between exoplanet populations and stellar properties and how they connect to planet formation in protoplanetary disks. Giant planets occur more frequently around more metal-rich and more massive stars. These findings support the core accretion theory of planet formation, in which the cores of giant planets form more rapidly in more metal-rich and more massive protoplanetary disks. Smaller planets, those with sizes roughly between Earth and Neptune, exhibit different scaling relations with stellar properties. These planets are found around stars with a wide range of metallicities and occur more frequently around lower mass stars. This indicates that planet formation takes place in a wide range of environments, yet it is not clear why planets form more efficiently around low mass stars. Going forward, exoplanet surveys targeting M dwarfs will characterize the exoplanet population around the lowest mass stars. In combination with ongoing stellar characterization, this will help us understand the formation of planets in a large range of environments.Comment: Accepted for Publication in the Handbook of Exoplanet

A Pilot Study of Abnormal Growth in Autism Spectrum Disorders and Other Childhood Psychiatric Disorders

The aims of the current study were to examine whether early growth abnormalities are (a) comparable in autism spectrum disorders (ASD) and other childhood psychiatric disorders, and (b) specific to the brain or generalized to the whole body. Head circumference, height, and weight were measured during the first 19 months of life in 129 children with ASD and 59 children with non-ASD psychiatric disorders. Both groups showed comparable abnormal patterns of growth compared to population norms, especially regarding height and head circumference in relation to height. Thus abnormal growth appears to be related to psychiatric disorders in general and is mainly expressed as an accelerated growth of height not matched by an increase in weight or head circumference

Adaptive individual variation in phenological responses to perceived predation levels

The adaptive evolution of timing of breeding (a component of phenology) in response to environmental change requires individual variation in phenotypic plasticity for selection to act upon. A major question is what processes generate this variation. Here we apply multi-year manipulations of perceived predation levels (PPL) in an avian predator-prey system, identifying phenotypic plasticity in phenology as a key component of alternative behavioral strategies with equal fitness payoffs. We show that under low-PPL, faster (versus slower) exploring birds breed late (versus early);the pattern is reversed under high-PPL, with breeding synchrony decreasing in conjunction. Timing of breeding affects reproductive success, yet behavioral types have equal fitness. The existence of alternative behavioral strategies thus explains variation in phenology and plasticity in reproductive behavior, which has implications for evolution in response to anthropogenic change

Evaluation of DNA ploidy in relation with established prognostic factors in patients with locally advanced (unresectable) or metastatic pancreatic adenocarcinoma: a retrospective analysis

<p>Abstract</p> <p>Background</p> <p>Most patients with ductal pancreatic adenocarcinoma are diagnosed with locally advanced (unresectable) or metastatic disease. The aim of this study was to evaluate the prognostic significance of DNA ploidy in relation with established clinical and laboratory variables in such patients.</p> <p>Methods</p> <p>Two hundred and twenty six patients were studied retrospectively. Twenty two potential prognostic variables (demographics, clinical parameters, biochemical markers, treatment modality) were examined.</p> <p>Results</p> <p>Mean survival time was 38.41 weeks (95% c.i.: 33.17–43.65), median survival 27.00 weeks (95% c.i.: 23.18–30.82). On multivariate analysis, 10 factors had an independent effect on survival: performance status, local extension of tumor, distant metastases, ploidy score, anemia under epoetin therapy, weight loss, pain, steatorrhoea, CEA, and palliative surgery and chemotherapy. Patients managed with palliative surgery and chemotherapy had 6.7 times lower probability of death in comparison with patients without any treatment. Patients with ploidy score > 3.6 had 5.0 times higher probability of death in comparison with patients with ploidy score < 2.2 and these with ploidy score 2.2–3.6 had 6.3 times higher probability of death in comparison with patients with ploidy score < 2.2.</p> <p>Conclusion</p> <p>According to the significance of the examined factor, survival was improved mainly by the combination of surgery and chemotherapy, and the presence of low DNA ploidy score.</p

A comparison of Child-Pugh, APACHE II and APACHE III scoring systems in predicting hospital mortality of patients with liver cirrhosis

BACKGROUND: The aim of this study was to assess the prognostic accuracy of Child-Pugh and APACHE II and III scoring systems in predicting short-term, hospital mortality of patients with liver cirrhosis. METHODS: 200 admissions of 147 cirrhotic patients (44% viral-associated liver cirrhosis, 33% alcoholic, 18.5% cryptogenic, 4.5% both viral and alcoholic) were studied prospectively. Clinical and laboratory data conforming to the Child-Pugh, APACHE II and III scores were recorded on day 1 for all patients. Discrimination was evaluated using receiver operating characteristic (ROC) curves and area under a ROC curve (AUC). Calibration was estimated using the Hosmer-Lemeshow goodness-of-fit test. RESULTS: Overall mortality was 11.5%. The mean Child-Pugh, APACHE II and III scores for survivors were found to be significantly lower than those of nonsurvivors. Discrimination was excellent for Child-Pugh (ROC AUC: 0.859) and APACHE III (ROC AUC: 0.816) scores, and acceptable for APACHE II score (ROC AUC: 0.759). Although the Hosmer-Lemeshow statistic revealed adequate goodness-of-fit for Child-Pugh score (P = 0.192), this was not the case for APACHE II and III scores (P = 0.004 and 0.003 respectively) CONCLUSION: Our results indicate that, of the three models, Child-Pugh score had the least statistically significant discrepancy between predicted and observed mortality across the strata of increasing predicting mortality. This supports the hypothesis that APACHE scores do not work accurately outside ICU settings

Planetary Rings

Planetary rings are the only nearby astrophysical disks, and the only disks that have been investigated by spacecraft. Although there are significant differences between rings and other disks, chiefly the large planet/ring mass ratio that greatly enhances the flatness of rings (aspect ratios as small as 1e-7), understanding of disks in general can be enhanced by understanding the dynamical processes observed at close-range and in real-time in planetary rings. We review the known ring systems of the four giant planets, as well as the prospects for ring systems yet to be discovered. We then review planetary rings by type. The main rings of Saturn comprise our system's only dense broad disk and host many phenomena of general application to disks including spiral waves, gap formation, self-gravity wakes, viscous overstability and normal modes, impact clouds, and orbital evolution of embedded moons. Dense narrow rings are the primary natural laboratory for understanding shepherding and self-stability. Narrow dusty rings, likely generated by embedded source bodies, are surprisingly found to sport azimuthally-confined arcs. Finally, every known ring system includes a substantial component of diffuse dusty rings. Planetary rings have shown themselves to be useful as detectors of planetary processes around them, including the planetary magnetic field and interplanetary impactors as well as the gravity of nearby perturbing moons. Experimental rings science has made great progress in recent decades, especially numerical simulations of self-gravity wakes and other processes but also laboratory investigations of coefficient of restitution and spectroscopic ground truth. The age of self-sustained ring systems is a matter of debate; formation scenarios are most plausible in the context of the early solar system, while signs of youthfulness indicate at least that rings have never been static phenomena.Comment: 82 pages, 34 figures. Final revision of general review to be published in "Planets, Stars and Stellar Systems", P. Kalas and L. French (eds.), Springer (http://refworks.springer.com/sss