Radioactive Iron Rain: Transporting 60^{60}Fe in Supernova Dust to the Ocean Floor

Several searches have found evidence of $^{60}$Fe deposition, presumably from a near-Earth supernova (SN), with concentrations that vary in different locations on Earth. This paper examines various influences on the path of interstellar dust carrying $^{60}$Fe from a SN through the heliosphere, with the aim of estimating the final global distribution on the ocean floor. We study the influences of magnetic fields, angle of arrival, wind and ocean cycling of SN material on the concentrations at different locations. We find that the passage of SN material through the mesosphere/lower thermosphere (MLT) is the greatest influence on the final global distribution, with ocean cycling causing lesser alteration as the SN material sinks to the ocean floor. SN distance estimates in previous works that assumed a uniform distribution are a good approximation. Including the effects on surface distributions, we estimate a distance of $46^{+10}_{-6}$ pc for a $8-10 \ M_{\odot}$ SN progenitor. This is consistent with a SN occurring within the Tuc-Hor stellar group $\sim$2.8 Myr ago with SN material arriving on Earth $\sim$2.2 Myr ago. We note that the SN dust retains directional information to within $1^{\circ}$ through its arrival in the inner Solar System, so that SN debris deposition on inert bodies such as the Moon will be anisotropic, and thus could in principle be used to infer directional information. In particular, we predict that existing lunar samples should show measurable $^{60}$Fe differences.Comment: 18 pages, 8 figures. Comments welcom

Astrophysical Shrapnel: Discriminating Among Near-Earth Stellar Explosion Sources of Live Radioactive Isotopes

We consider the production and deposition on Earth of isotopes with half-lives in the range 10$^{5}$ to 10$^{8}$ years that might provide signatures of nearby stellar explosions, extending previous analyses of Core-Collapse Supernovae (CCSNe) to include Electron-Capture Supernovae (ECSNe), Super-Asymptotic Giant Branch (SAGBs) stars, Thermonuclear/Type Ia Supernovae (TNSNe), and Kilonovae/Neutron Star Mergers (KNe). We revisit previous estimates of the $^{60}$Fe and $^{26}$Al signatures, and extend these estimates to include $^{244}$Pu and $^{53}$Mn. We discuss interpretations of the $^{60}$Fe signals in terrestrial and lunar reservoirs in terms of a nearby stellar ejection ~2.2 Myr ago, showing that (i) the $^{60}$Fe yield rules out the TNSN and KN interpretations, (ii) the $^{60}$Fe signals highly constrain a SAGB interpretation but do not completely them rule out, (iii) are consistent with a CCSN origin, and (iv) are highly compatible with an ECSN interpretation. Future measurements could resolve the radioisotope deposition over time, and we use the Sedov blast wave solution to illustrate possible time-resolved profiles. Measuring such profiles would independently probe the blast properties including distance, and would provide additional constraints the nature of the explosion.Comment: 38 pages, 6 figures. Comments welcom

Participatory mass observation and citizen science.

The authors outline and reflect upon a new research agenda on participatory mass observation and citizen science as an introduction to the 3 project outlines in this special section of Transactions

Money: A General Purpose Social Utility

In June this year 2019 my attention was drawn to the publication of a new book by Tony Lawson The Nature of Social Reality Issues in Social Ontology London and New York Routledge I wrote to him to introduce myself and express my interest I did so because this is what I have been working on since about 2005 My book The Metaphysics of Scientific Realism 2009 was an argument for the acceptance of scientific realism as a First Philosophy i e as a foundation for all other philosophies The 2012 book Social Humanism A New Metaphysics was my first serious attempt to create an adequate scientifically realistic metaphysics for the social sciences It dealt mainly with human nature and with the social structure of human societies The anthropological evidence is that all human tribes even the most primitive have social structures that define the roles and responsibilities of their members These structures generally aim to minimise conflict within and promote the interests of the tribe or nation without I call it the de facto social contract of the societ

Tax Problems in Sales to Controlled Corporations

Mr. Ellis examines the tax consequences arising when a taxpayer sells appreciated property to a controlled corporation in order to realize a capital gain for himself as well as to increase the basis of the property. He points out the dangers inherent in such a transaction and suggests precautions which should be taken to obtain favorable tax treatment. The author concludes that a taxpayer transferring appreciated property to a controlled corporation may achieve substantial tax benefits because of the relative ineffectiveness of sections 351 and 1239; however, it will be almost impossible for a taxpayer to recognize a loss on the transfer of depreciated property because of section 267

Field Evaluation of Herbicides on Vegetables and Small Fruits 2004

Herbicide evaluation studies on vegetables and small fruits were conducted in 2004 at the Arkansas Agricultural Experiment Station at Fayetteville, AR, in an effort to evaluate new herbicides, herbicide mixtures, and their application timings for weed control efficacy and crop tolerance. Results of these studies, in part, provide useful information to producers, fellow researchers, the Crop Protection Industry, and the IR-4 Minor Crop Pest Management Program in the development of potential new herbicide uses in vegetable, and fruit

FRONTAL SURFACE AREA AS A PREDICTOR OF CYCLING PERFORMANCE

The equation of motion of a cyclist indicates that at a constant velocity the largest morphological influence on the cyclists retarding force is the projected frontal surface area. Nevertheless, parameters profiling a cyclists physical ability such as V02 max, work done in a given time or the power output achieved at the anaerobic threshold are usually normalized to body mass when making comparisons between athletes. This study examined if cycling time trial performance could be better predicted from a physical parameter normalized to frontal surface area rather than normalized to body mass. A group (n=7) of male juvenile cyclists (14-16 yrs) and a group (n=l 1) of male junior cyclists (16-18 yrs) performed a five minute maximum effort test on a wind braked bicycle ergometer. Peak power and total work done were measured. Each cyclists frontal surface area on the bicycle was determined by a regression equation using height and weight (Mclean 1993). The juvenile cyclists competed in a 10 km flat time trial while the juniors competed in a 15 km flat time trial. Triathlon style aerodynamic handlebars were not used. For both the juvenile and junior groups correlation analysis showed that time trial time was better predicted by total work/FSA (r=-.82 and -.86 respectively) rather than by total work/body mass (I=-.53, I=-.74) or total work alone (I= .67 I= .65). It was concluded that parameters describing a cyclists physical ability should be normalized to FSA rather than body mass when making comparisons between athletes