Lateral Expansion of the Bridges of Cygnus A and other Powerful Radio Sources

Measurements of the width of the radio bridge at several locations along the bridge for each of four powerful extended radio sources are presented. Adopting a few simple assumptions, these measurements may be used to predict the radio surface brightness as a function of position across the radio bridge. The predicted and observed surface brightnesses across the bridges are compared and found to agree fairly well. The results are consistent with a simple picture in which the radio power and size of the radio lobe at the forward edge of the radio bridge are roughly time-independent for a given source, and the expansion of the bridge in the lateral direction is adiabatic. There is no indication that reacceleration or energy transport is important in the bridges of these sources. The rate of lateral expansion of the bridge just behind the radio lobe and hotspot in terms of the rate of forward propagation is compared with that predicted, and found to be in good agreement with the predicted value.Comment: 7 pages, uuencoded compressed postscript. To appear in the Proceding of the Cygnus A workshop, May 1-4, Green Bank, W

Evidence, Miracles, and the Existence of Jesus: Comments on Stephen Law

We use Bayesian tools to assess Law’s skeptical argument against the historicity of Jesus. We clarify and endorse his sub-argument for the conclusion that there is good reason to be skeptical about the miracle claims of the New Testament. However, we dispute Law’s contamination principle that he claims entails that we should be skeptical about the existence of Jesus. There are problems with Law’s defense of his principle, and we show, more importantly, that it is not supported by Bayesian considerations. Finally, we show that Law’s principle is false in the specific case of Jesus and thereby show, contrary to the main conclusion of Law’s argument, that biblical historians are entitled to remain confident that Jesus existed

How to Estimate Custom Machinery Rates

Specialization in agriculture, along with larger farm sizes and bigger equipment, has resulted in more custom machinery work being conducted on farms. Often, there is limited data about the current custom rate. The Mississippi State Budget Generator (MSBG) is a tool that uses a cost approach to allocating machinery cost on a per acre basis and can be used in situations where custom rates are not well known. When compared to actual custom work surveys, the MSBG provides rates that are lower than the survey results. One explanation is that the MSBG does not include any built-in profit.Agribusiness, Production Economics,

Type Classes for Lightweight Substructural Types

Linear and substructural types are powerful tools, but adding them to standard functional programming languages often means introducing extra annotations and typing machinery. We propose a lightweight substructural type system design that recasts the structural rules of weakening and contraction as type classes; we demonstrate this design in a prototype language, Clamp. Clamp supports polymorphic substructural types as well as an expressive system of mutable references. At the same time, it adds little additional overhead to a standard Damas-Hindley-Milner type system enriched with type classes. We have established type safety for the core model and implemented a type checker with type inference in Haskell.Comment: In Proceedings LINEARITY 2014, arXiv:1502.0441

Luminosities and mass-loss rates of Local Group AGB stars and Red Supergiants

We aim to investigate mass loss and luminosity in a large sample of evolved stars in several Local Group galaxies with a variety of metalliticies and star-formation histories: the Small and Large Magellanic Cloud, and the Fornax, Carina, and Sculptor dwarf spheroidal galaxies. Dust radiative transfer models are presented for 225 carbon stars and 171 oxygen-rich evolved stars for which spectra from the Infrared Spectrograph on Spitzer are available. The spectra are complemented with available optical and infrared photometry to construct spectral energy distributions. A minimization procedure was used to determine luminosity and mass-loss rate (MLR). Pulsation periods were derived for a large fraction of the sample based on a re-analysis of existing data. New deep K-band photometry from the VMC survey and multi-epoch data from IRAC and AllWISE/NEOWISE have allowed us to derive pulsation periods longer than 1000 days for some of the most heavily obscured and reddened objects. We derive (dust) MLRs and luminosities for the entire sample. The estimated MLRs can differ significantly from estimates for the same objects in the literature due to differences in adopted optical constants (up to factors of several) and details in the radiative transfer modelling. Updated parameters for the super-AGB candidate MSX SMC 055 (IRAS 00483-7347) are presented. Its current mass is estimated to be 8.5 +- 1.6 \msol, suggesting an initial mass well above 8~\msol. Using synthetic photometry, we present and discuss colour-colour and colour-magnitude diagrams which can be expected from the James Webb Space Telescope.Comment: A&A accepted. The full version (100 pages, 12 MB) with complete tables and all figures of the appendices is available at http://homepage.oma.be/marting/articlesgroen.htm