Bayesian Asteroseismology of 23 Solar-Like Kepler Targets

We study 23 previously published Kepler targets to perform a consistent grid-based Bayesian asteroseismic analysis and compare our results to those obtained via the Asteroseismic Modelling Portal (AMP). We find differences in the derived stellar parameters of many targets and their uncertainties. While some of these differences can be attributed to systematic effects between stellar evolutionary models, we show that the different methodologies deliver incompatible uncertainties for some parameters. Using non-adiabatic models and our capability to measure surface effects, we also investigate the dependency of these surface effects on the stellar parameters. Our results suggest a dependence of the magnitude of the surface effect on the mixing length parameter which also, but only minimally, affects the determination of stellar parameters. While some stars in our sample show no surface effect at all, the most significant surface effects are found for stars that are close to the Sun's position in the HR diagram.Comment: 14 pages, 9 figures, accepted for publication in MNRA

Of Bodies Politic and Pecuniary: A Brief History of Corporate Purpose

American corporate law has long drawn a bright line between for-profit and non-profit corporations. In recent years, hybrid or social enterprises have increasingly put this bright-line distinction to the test. This Article asks what we can learn about the purpose of the American business corporation by examining its history and development in the United States in its formative period from roughly 1780-1860. This brief history of corporate purpose suggests that the duty to maximize profits in the for-profit corporation is a relatively recent development. Historically, the American business corporation grew out of an earlier form of corporation that was neither for-profit nor nonprofit in today’s parlance but rather, served a multitude of municipal, religious, charitable, educational, and eventually business purposes in early nineteenth-century New England. The purposes of early American business corporations—rather than maximization of profit to private shareholders—were often overtly public, involving development of local transportation, finance, and other much-needed economic infrastructure. With the rise of factory-based manufacturing, railroads, and other capital-intensive industries in the middle decades of the nineteenth century and the advent of general incorporation statutes, the purpose of the American business corporation shifted fundamentally from public to private. By 1860, the stage was set for the modern firm. This Article concludes that the corporation has no intrinsic purpose. The corporation’s defining features are separate legal personality and the ability to aggregate capital toward any otherwise lawful end, whether for-profit or nonprofit. Social enterprises today more closely resemble the early American business corporation than the profit-maximizing modern firm. Social enterprise should be seen less as a legally uncertain novelty than a return to the business corporation’s nineteenth-century American roots. Finally, this Article suggests potential limitations for social enterprise

The Limited Public Offer in German and U.S. Securities Law: A Comparative Analysis of Prospectus Act Section 2(2) and Rule 505 of Regulation D

This Note examines the limited circle of persons exception in section 2(2) of the Prospectus Act in comparison to similar provisions of U.S. federal securities law, particularly Section 3(b) of the Securities Act of 1933 (the Securities Act ) and Rule 505 of Regulation D ( Rule 505 ). Comparison of the Prospectus Act to U.S. securities law seems both warranted and useful. Certain aspects of German securities law are broadly modeled on U.S. precedents. U.S. securities laws reflect more than sixty-five years of experience defining (and re-defining) public and limited public offers and private placements. U.S. securities regulators have also displayed in recent years an increasing concern, widely shared by their German counterparts, for the needs and difficulties of small businesses in capital formation. The Prospectus Act and Regulation D are joined by common policies and provisions in this regard. A clear definition of the term limited circle of persons as used in Prospectus Act section 2(2) and a correspondingly clear and available small business exception to the requirements of the Prospectus Act would seem desirable

Of Bodies Politic and Pecuniary: A Brief History of Corporate Purpose

American corporate law has long drawn a bright line between for-profit and non-profit corporations. In recent years, hybrid or social enterprises have increasingly put this bright-line distinction to the test. This Article asks what we can learn about the purpose of the American business corporation by examining its history and development in the United States in its formative period from roughly 1780-1860. This brief history of corporate purpose suggests that the duty to maximize profits in the for-profit corporation is a relatively recent development. Historically, the American business corporation grew out of an earlier form of corporation that was neither for-profit nor nonprofit in today’s parlance but rather, served a multitude of municipal, religious, charitable, educational, and eventually business purposes in early nineteenth-century New England. The purposes of early American business corporations—rather than maximization of profit to private shareholders— were often overtly public, involving development of local transportation, finance, and other much-needed economic infrastructure. With the rise of factory-based manufacturing, railroads, and other capital-intensive industries in the middle decades of the nineteenth century and the advent of general incorporation statutes, the purpose of the American business corporation shifted fundamentally from public to private. By 1860, the stage was set for the modern firm. This Article concludes that the corporation has no intrinsic purpose. The corporation’s defining features are separate legal personality and the ability to aggregate capital toward any otherwise lawful end, whether for-profit or nonprofit. Social enterprises today more closely resemble the early American business corporation than the profit-maximizing modern firm. Social enterprise should be seen less as a legally uncertain novelty than a return to the business corporation’s nineteenth-century American roots. Finally, this Article suggests potential limitations for social enterprise

Tracing early stellar evolution with asteroseismology: pre-main sequence stars in NGC 2264

Asteroseismology has been proven to be a successful tool to unravel details of the internal structure for different types of stars in various stages of their main sequence and post-main sequence evolution. Recently, we found a relation between the detected pulsation properties in a sample of 34 pre-main sequence (pre-MS) delta Scuti stars and the relative phase in their pre-MS evolution. With this we are able to demonstrate that asteroseismology is similarly powerful if applied to stars in the earliest stages of evolution before the onset of hydrogen core burning.Comment: CoRoT Symposium 3 / Kepler KASC-7 joint meeting, Toulouse, July 2014. To be published by EPJ Web of Conference

X-ray Properties of Low-Mass Pre-Main Sequence Stars in the Orion Trapezium Cluster

The Chandra High Energy Transmission Gratings (HETG) Orion Legacy Project (HOLP) is the first comprehensive set of observations of a very young massive stellar cluster which provides high resolution X-ray spectra of very young stars over a wide mass range (0.7 - 2.3 Msun). In this paper, we focus on the six brightest X-ray sources with T Tauri stellar counterparts which are well-characterized at optical and infra-red wavelengths. All stars show column densities which are substantially smaller than expected from optical extinction indicating that the sources are located on the near side of the cluster with respect to the observer as well as that these stars are embedded in more dusty environments. Stellar X-ray luminosities are well above $10^{31}$ erg/s, in some cases exceeding $10^{32}$ erg/s for a substantial amount of time. The stars during these observations show no flares but are persistently bright. The spectra can be well fit with two temperature plasma components of 10 MK and 40 MK, of which the latter dominates the flux by a ratio 6:1 on average. The total EMs range between 3 - 8$\times10^{54}$ cm$^{-3}$ and are comparable to active coronal sources. Limits on the forbidden to inter-combination line ratios in the He-Like K-shell lines show that we observe a predominantely optically thin plasma with electron densities below $10^{12}$ cm$^{-3}$. Observed abundances compare well with active coronal sources underlying the coronal nature of these sources. The surface flux in this sample of 0.6 to 2.3 Msun classical T Tauri stars shows that coronal activity and possibly coronal loop size increase significantly between ages 0.1 to 10 Myrs.Comment: 13 pages, 12 figures, submitted to the Astrophysical Journa

Modelling Trust Relationships in a Healthcare Network: Experiences with the TCD Framework

We report on the application of the Trust-Confidence-Distrust (TCD) framework of Gans et al. (2003) to the task of modeling trust relationships in a large metropolitan health service. We investigated the relationships between an acute stroke ward and a specialist stroke rehabilitation ward by examining the patient handover process that links each ward’s activities. The case study provided evidence that the model works in real-life settings. In addition, we gained valuable insights in the applicability of the framework in a formal organizational, rather than more loosely connected network setting

Learn or Earn? - Intelligent Task Recommendation for Competitive Crowdsourced Software Development

Background: Competitive crowdsourced development encourages online software developers to register for tasks offered on the crowdsourcing platform and implement them in a competitive mode. As a large number of tasks are uploaded daily, the scenery of competition is changing continuously. Without appropriate decision support, online developers often make task decisions in an ad hoc and intuitive manner. Aims: To provide dynamic decision support for crowd developers to select the task that fit best to their personal learning versus earning objectives, taking into account the actual competitiveness situation. Method: We propose a recommendation system called EX2 ( EX-Square ) that combines both explorative ( learn ) and exploitative ( earn ) search for tasks, based on a systematic analysis of workers preference patterns, technologies hotness, and the projection of winning chances. The implemented prototype allows dynamic recommendations that reflect task updates and competition dynamics at any given time. Results: Based on evaluation from 4007 tasks monitored over a period of 2 years, we show that EX2 can explore and adjust task recommendations corresponding to context changes, and individual learning preferences of workers. A survey was also conducted with 14 actual crowd workers, showing that intelligent decision support from EX2 is considered useful and valuable. Conclusions: With support from EX2, workers benefit from the tool from getting customized recommendations, and the platform provider gets a higher chance to better cover the breadth of technology needs in case recommendations are taken