Probabilistic Mass-Radius Relationship for Sub-Neptune-Sized Planets

The Kepler Mission has discovered thousands of planets with radii $<4\ R_\oplus$, paving the way for the first statistical studies of the dynamics, formation, and evolution of these sub-Neptunes and super-Earths. Planetary masses are an important physical property for these studies, and yet the vast majority of Kepler planet candidates do not have theirs measured. A key concern is therefore how to map the measured radii to mass estimates in this Earth-to-Neptune size range where there are no Solar System analogs. Previous works have derived deterministic, one-to-one relationships between radius and mass. However, if these planets span a range of compositions as expected, then an intrinsic scatter about this relationship must exist in the population. Here we present the first probabilistic mass-radius relationship (M-R relation) evaluated within a Bayesian framework, which both quantifies this intrinsic dispersion and the uncertainties on the M-R relation parameters. We analyze how the results depend on the radius range of the sample, and on how the masses were measured. Assuming that the M-R relation can be described as a power law with a dispersion that is constant and normally distributed, we find that$M/M_\oplus=2.7(R/R_\oplus)^{1.3}$, a scatter in mass of$1.9\ M_\oplus$, and a mass constraint to physically plausible densities, is the "best-fit" probabilistic M-R relation for the sample of RV-measured transiting sub-Neptunes ($R_{pl}<4\ R_\oplus$). More broadly, this work provides a framework for further analyses of the M-R relation and its probable dependencies on period and stellar properties.Comment: 14 pages, 5 figures, 2 tables. Accepted to the Astrophysical Journal on April 28, 2016. Select posterior samples and code to use them to compute the posterior predictive mass distribution are available at https://github.com/dawolfgang/MRrelatio

PSD-95 Is Associated with the Postsynaptic Density and Not with the Presynaptic Membrane at Forebrain Synapses

PSD-95, a prominent protein component of the postsynaptic density (PSD) fraction from rat forebrain, has been localized by light microscopy to dendrites of hippocampal neurons (Cho et al., 1992) and to the presynaptic plexus of cerebellar basket cells (Kistner et al., 1993). Here we extend these studies to show that an affinity-purified antibody to PSD-95 labels the dendrites of most neurons in the forebrain and of a subset of neurons in the cerebellum. To confirm that PSD-95 is associated with the PSD at forebrain synapses and to clarify whether it is also associated with the presynaptic membrane, we employed immunogold electron microscopy of forebrain synaptosomes. Gold-labeled antibodies to PSD-95 labeled postsynaptic densities in both intact and lysed forebrain synaptosomes but did not label presynaptic terminals or the presynaptic membrane. The asymmetric distribution of PSD-95 at synapses contrasts with that of its homologs, disks-large and ZO-1, which are arranged symmetrically at septate and tight junctions, respectively

Three-dimensional coating and rimming flow: a ring of fluid on a rotating horizontal cylinder

The steady three-dimensional flow of a thin, slowly varying ring of Newtonian fluid on either the outside or the inside of a uniformly rotating large horizontal cylinder is investigated. Specifically, we study “full-ring” solutions, corresponding to a ring of continuous, finite and non-zero thickness that extends all the way around the cylinder. In particular, it is found that there is a critical solution corresponding to either a critical load above which no full-ring solution exists (if the rotation speed is prescribed) or a critical rotation speed below which no full-ring solution exists (if the load is prescribed). We describe the behaviour of the critical solution and, in particular, show that the critical flux, the critical load, the critical semi-width and the critical ring profile are all increasing functions of the rotation speed. In the limit of small rotation speed, the critical flux is small and the critical ring is narrow and thin, leading to a small critical load. In the limit of large rotation speed, the critical flux is large and the critical ring is wide on the upper half of the cylinder and thick on the lower half of the cylinder, leading to a large critical load.\ud \ud We also describe the behaviour of the non-critical full-ring solution, and, in particular, show that the semi-width and the ring profile are increasing functions of the load but, in general, non-monotonic functions of the rotation speed. In the limit of large rotation speed, the ring approaches a limiting non-uniform shape, whereas in the limit of small load, the ring is narrow and thin with a uniform parabolic profile. Finally, we show that, while for most values of the rotation speed and the load the azimuthal velocity is in the same direction as the rotation of the cylinder, there is a region of parameter space close to the critical solution for sufficiently small rotation speed in which backflow occurs in a small region on the right-hand side of the cylinder

Thermoviscous Coating and Rimming Flow

A comprehensive description is obtained of steady thermoviscous (i.e. with temperature-dependent viscosity) coating and rimming flow on a uniformly rotating horizontal cylinder that is uniformly hotter or colder than the surrounding atmosphere. It is found that, as in the corresponding isothermal problem, there is a critical solution with a corresponding critical load (which depends, in general, on both the Biot number and the thermoviscosity number) above which no ``full-film'' solutions corresponding to a continuous film of fluid covering the entire outside or inside of the cylinder exist. The effect of thermoviscosity on both the critical solution and the full-film solution with a prescribed load is described. In particular, there are no full-film solutions with a prescribed load M for any value of the Biot number when M is greater than or equal to M_{c0} divided by the square root of f for positive thermoviscosity number and when M is greater than M_{c0} for negative thermoviscosity number, where f is a monotonically decreasing function of the thermoviscosity number and M_{c0} = 4.44272 is the critical load in the constant-viscosity case. It is also found that when the prescribed load M is less than 1.50315 there is a narrow region of the Biot number - thermoviscosity number parameter plane in which backflow occurs

Genome editing in non-model organisms opens new horizons for comparative physiology

For almost 100 years, biologists have made fundamental discoveries using a handful of model organisms that are not representative of the rich diversity found in nature. The advent of CRISPR genome editing now opens up a wide range of new organisms to mechanistic investigation. This increases not only the taxonomic breadth of current research but also the scope of biological problems that are now amenable to study, such as population control of invasive species, management of disease vectors such as mosquitoes, the creation of chimeric animal hosts to grow human organs and even the possibility of resurrecting extinct species such as passenger pigeons and mammoths. Beyond these practical applications, work on non-model organisms enriches our basic understanding of the natural world. This special issue addresses a broad spectrum of biological problems in non-model organisms and highlights the utility of genome editing across levels of complexity from development and physiology to behaviour and evolution

Cohort, Year and Age Effects in Canadian Wage Data

We use Canadian Surveys of Consumer Finances 1971-1993 to study the wages of full-time, full-year male and female workers. Median real wages of 24-year-old males without a university degree fell by 25% between 1978 and 1993. For 24-year-old females the decline was more modest and reversed in 1987, but real wages in 1993 were still significantly lower than they were in 1978. We investigate whether these changes are permanent "cohort" effects or more temporary "year" effects. Graphs of median wages against year and age indicate some periods where year effects are more prominent than cohort effects and other periods where the reverse is true. We then compare the results from two models, one assigning the trends to year effects, the other assigning them to cohort effects, and use these models to produce real wage projections.SCF; wages; cohort

A Comparison of Methodologies for Valuing Decreased Health Effects from Wildfire Smoke

Wildfire seasons are becoming longer and more intense throughout the world, making it increasingly important to monetize the full damages caused by wildfires when analyzing various fire management policies. We estimate the economic costs of the health effects associated with exposure to wildfire smoke using a simple cost of illness approach and for the first time to our knowledge we estimate willingness-to-pay (WTP) for a decrease in symptom days from wildfire smoke using the contingent valuation method and the averting behavior method. Comparing estimates across all three common approaches for estimating the economic cost of exposure to an air pollutant is an important contribution to the literature. This study uses data from the largest wildfire in Los Angeles County’s modern history, the Station Fire of 2009. Our results show that a simple cost of illness estimate is about $3 per day of symptoms, the averting behavior method results in a WTP value of$43 or $94 to avoid one day of wildfire-smoke induced symptom days, depending on the model used, and the contingent valuation method results in a WTP estimate of$74 - $98 to avoid one day of wildfire-smoke induced symptom days, depending on model specification.averting behavior method, contingent valuation method, cost of illness, wildfire smoke, health, morbidity, Environmental Economics and Policy, Health Economics and Policy, Q,

Promoting Team-Based Exercise Among African American Breast Cancer Survivors

Physical activity benefits the health and well-being of breast cancer survivors (BCS). Yet, many African American survivors do not routinely exercise and have increased risk of poor outcomes. The purpose of this mixed-method study was to identify motivational factors compelling African American BCS to participate in a 14-week team walking program and to intend to continue exercise after the intervention concluded. Focus groups were held with participants (n = 12) before and after training. Content analysis discovered themes before the intervention: Not wanting to go at it alone, exercise not a life or treatment priority, cancer treatment affected activity, advocates to exercise, and can exercise really help? Four themes postintervention themes included: In the same boat, changed mind-set, improved weight and activity, and overcoming barriers. Physical data verified improvements. Results suggest that a team-based exercise training program may assist in overcoming a sedentary behavior tendency and subsequently improve health among survivors

Survivors Speak: A Qualitative Analysis of Motivational Factors Influencing Breast Cancer Survivors’ Participation in a Sprint Distance Triathlon

Aims and Objectives To examine motivational factors influencing breast cancer survivors to participate in triathlon training, complete a triathlon and maintain an exercise thereafter. Background Routine exercise has been shown to improve quality of life and reduce recurrence for breast cancer survivors. Yet physical and psychological factors present barriers for initiating and maintaining an exercise routine. Research is limited in exploring factors of exercise motivation from the survivor\u27s perspective. Design Qualitative design using focus groups and individual follow-up phone interviews to explore motivation for exercise initiation and maintenance. Methods One to two weeks after completing a triathlon, 11 breast cancer survivors who trained together participated in one of three focus groups to discuss their experience. Five months post triathlon 6 of the 11 participants were successfully contacted and phone interviews were conducted to explore exercise maintenance. Focus groups and interviews were analysed using content and thematic analysis. Results Five themes emerged (1) Champion for Exercise, (2) Part of a Team, (3) Everyone Had a Story, (4) Not Really Exercise and (5) What Do We Do Now? Overall, survivors recognised their need for lifestyle change (e.g. moving from a sedentary lifestyle to a more active one). More importantly, they identified the team approach to exercise initiation was crucial in their success in sustaining a behavioural change. Conclusions Emphasis needed on developing team exercise training programmes for survivors. Nurses can play a critical role in discussing with survivors, the benefits of exercise initiation and maintenance. Relevance to clinical practice Breast cancer survivors are hesitant to initiate routine exercise. Training with women who share a common lived experience increases the likelihood of success. Nurses are in a position to encourage breast cancer survivors to participate in group exercise programmes as a way to improve quality of life