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

The Ever-Shifting Internet Population

Presents findings from surveys conducted between March and May 2002. Takes a new look at Internet access and the digital divide. Explores factors of cost, lack of technology skills, and physical access (particularly for persons with disabilities)

The One I Loved On South Carolina Shore : Tenor And Baritone

https://digitalcommons.library.umaine.edu/mmb-vp/4487/thumbnail.jp

A Communication Approach to Confronting Poverty: Creating Interactional Capital and Building Cross-Class Community through Collective Communicative Practices in the Boulder County Circles Campaign

This qualitative, ethnographic research study documented the use and effects of collective communicative practices (CCPs) employed by an organization, called Circles, that aims to create community among a group of diverse people from different socioeconomic classes, including those who currently live in poverty, for the purpose of aiding the efforts of those who are impoverished to move out of poverty. Using data collected from participant interviews, questionnaires, participant-observation, and Circles documents, the research findings suggest a new conception of the communication being promoted through Circles, called interactional capital, which describes the types of communication and other communicative resources that facilitate the creation and maintenance of social capital through interactions with others. The discussion chapter examines the nature and impact of interactional capital on participants at the individual, collective, and societal levels; and it explicates implications of the study, both theoretically--with respect to relationships among poverty, communication, and community--and practically, with regard to what lessons learned from this analysis suggest might be best practices for antipoverty programs, including Circles

Preferences for explanation generality develop early in biology but not physics

One of the core functions of explanation is to support prediction and generalization. However, some explanations license a broader range of predictions than others. For instance, an explanation about biology could be presented as applying to a specific case (e.g., “this bear”) or more generally across “all animals.” The current study investigated how 5- to 7-year-olds (N=36), 11- to 13-year-olds (N=34), and adults (N=79) evaluate explanations at varying levels of generality in biology and physics. Findings revealed that even the youngest children preferred general explanations in biology. However, only older children and adults preferred explanation generality in physics. Findings are discussed in light of differences in our intuitions about biological and physical principles

Antimicrobial Susceptibility Testing of Mycobacterium bovis Isolates from Michigan White-Tailed Deer during the 2009 Hunting Season

Michigan has had an ongoing outbreak of endemic Mycobacterium bovis which has been recognized within and sustained by its free-ranging white-tailed deer population since 1994. Worldwide, organisms within the Mycobacterium tuberculosis complex have exhibited the ability to develop resistance to antimicrobial agents, resulting in both the multidrug-resistant (MDR) and extensively drug-resistant (XDR) strains of human tuberculosis. Michigan's Bovine Tuberculosis Working Group has conducted active antimicrobial susceptibility testing on wildlife isolates of the endemic M. bovis organism at five-year intervals to detect any emerging drug resistance patterns. The results of 33 white-tailed deer origin isolates collected from the 2009 hunting season are reported here. There continues to be no evidence of any drug resistance except for pyrazinamide resistance. These results are likely due to the lack of antibacterial treatment applied to either wildlife or domestic animals which would provide selection pressure for the development of drug resistance

Beyond 2-D Mass-Radius Relationships: A Nonparametric and Probabilistic Framework for Characterizing Planetary Samples in Higher Dimensions

Fundamental to our understanding of planetary bulk compositions is the relationship between their masses and radii, two properties that are often not simultaneously known for most exoplanets. However, while many previous studies have modeled the two-dimensional relationship between planetary mass and radii, this approach largely ignores the dependencies on other properties that may have influenced the formation and evolution of the planets. In this work, we extend the existing nonparametric and probabilistic framework of \texttt{MRExo} to jointly model distributions beyond two dimensions. Our updated framework can now simultaneously model up to four observables, while also incorporating asymmetric measurement uncertainties and upper limits in the data. We showcase the potential of this multi-dimensional approach to three science cases: (i) a 4-dimensional joint fit to planetary mass, radius, insolation, and stellar mass, hinting of changes in planetary bulk density across insolation and stellar mass; (ii) a 3-dimensional fit to the California Kepler Survey sample showing how the planet radius valley evolves across different stellar masses; and (iii) a 2-dimensional fit to a sample of Class-II protoplanetary disks in Lupus while incorporating the upper-limits in dust mass measurements. In addition, we employ bootstrap and Monte-Carlo sampling to quantify the impact of the finite sample size as well as measurement uncertainties on the predicted quantities. We update our existing open-source user-friendly \texttt{MRExo} \texttt{Python} package with these changes, which allows users to apply this highly flexible framework to a variety of datasets beyond what we have shown here.Comment: Accepted in ApJ. Updated MRExo package and sample scripts available here: https://github.com/shbhuk/mrexo/tree/v1.0dev. Package will be released on PyPI (pip) along with full documentation upon publication in Ap

Identification of Four Potential Epigenetic Modulators from the NCI Structural Diversity Library Using a Cell-Based Assay

Epigenetic pathways help control the expression of genes. In cancer and other diseases, aberrant silencing or overexpression of genes, such as those that control cell growth, can greatly contribute to pathogenesis. Access to these genes by the transcriptional machinery is largely mediated by chemical modifications of DNA or histones, which are controlled by epigenetic enzymes, making these enzymes attractive targets for drug discovery. Here we describe the characterization of a locus derepression assay, a fluorescence-based mammalian cellular system which was used to screen the NCI structural diversity library for novel epigenetic modulators using an automated imaging platform. Four structurally unique compounds were uncovered that, when further investigated, showed distinct activities. These compounds block the viability of lung cancer and melanoma cells, prevent cell cycle progression, and/or inhibit histone deacetylase activity, altering levels of cellular histone acetylation