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

The Semisecret Life of Late Mao-Era International Law Scholarship

This Article is delimited by a focus on international law scholarship during the late Mao era, not on the PRC’s actual approach to or pronouncements on international law, mainly in order to respond directly to the assertion of U.S.-based international law scholars on late Mao-era scholarship. Of course, considerable ambiguity surrounds what constitutes scholarly work; no legal or even consensus definition generally exists. To be clear, definitions might exist in specific contexts such as the Foreign Agents Registration Act (“FARA”) of the United States, which prohibits foreign lobbying except for “bonafide religious, scholastic, academic or scientific pursuits or the fine arts,” inter alia, although the distinction between scholarly and other types of activities is left entirely ambiguous under the legislation and the case law. In this particular context, Chiu signaled in 1966 what he might have meant by scholarly when he added the qualification to similar assertions from the past that Mao-era international law commentators exhibited “a lack of interest in original studies of international law problems,” suggesting that his definition of scholarly requires an element of originality and intellectual rigor concerning clearly identified problems. Whether the plain-language definition of scholarly contains such elements depends on which dictionary one consults. The Oxford English Dictionary refers to “learned, erudite” for its definition. The Cambridge English Dictionary defines scholarly as “containing a serious, detailed study of a subject,” which suggests the same type of study that a learned or erudite person would undertake. As this Article looks at U.S.based international law scholars, it might be helpful to look at U.S. dictionaries. The Merriam-Webster dictionary provides a similar definition as that of the Oxford English Dictionary— “of, characteristic of, or suitable to learned persons.” Collins Dictionary provides a first definition of “learned” and then a second of “having or showing much knowledge, accuracy, and critical ability.” Of course, accuracy might depend on the viewer’s perspective and the referent employed. Regardless, an amalgam of these definitions would include a large measure of detailed knowledge and serious independence in expressing that detailed knowledge, which presumably would create some form of originality in addressing the problem at issue. This Article uses all three elements—knowledge, independence and originality—to assess whether a particular Mao-era work between 1965 and 1979 represents a scholarly contribution. This is distinguished from non-scholarly contributions, which may relate to education but more closely resemble indoctrination and political propaganda

The Rising Age Gap in Economic Well-Being

Compares changes in median net worth of households between 1984 and 2009 by age of head of household. Examines contributing factors, including the housing market bubble, the 2007-09 recession's effect on employment, and longer-term demographic trends

QED in strong, finite-flux magnetic fields

Lower bounds are placed on the fermionic determinants of Euclidean quantum electrodynamics in two and four dimensions in the presence of a smooth, finite-flux, static, unidirectional magnetic field $B(r) =(0,0,B(r))$, where $B(r) \geq 0$ or $B(r) \leq 0$, and $r$ is a point in the xy-plane.Comment: 10 pages, postscript (in uuencoded compressed tar file

Modelling Water Trade in the Southern Murray-Darling Basin

Released in November 2004, the paper uses TERM-Water, a bottoms-up regional CGE model of the Australian economy, to examine the regional effects of expanding trade of irrigation water in the southern Murray- Darling Basin. The study finds that water trading dampens the impact of water allocation cuts on gross regional product (GRP). The benefits of introducing trading within irrigation districts are greater than the further benefits of expanding trade to between these regions. Permitting trade of seasonal allocations allows irrigators to reallocate water in reaction to climatic conditions and water availability - and it is this flexibility that enables GRP reductions to be minimised.southern murray-darling basin, CGE model, irrigation water, water allocation, water trade,

Fermion Determinants

The current status of bounds on and limits of fermion determinants in two, three and four dimensions in QED and QCD is reviewed. A new lower bound on the two-dimensional QED determinant is derived. An outline of the demonstration of the continuity of this determinant at zero mass when the background magnetic field flux is zero is also given.Comment: 10 page