A critical review of charged particle astronomy at Saturn: The evidence for co-orbiting material in the inner satellite system

The charged particle observations from Pioneer and Voyager at Saturn were reassessed with a view towards providing limits on the amount of unseen dust and debris that may exist in the Saturnian system. Such estimates are crucial for planning the Cassini tour of Saturn. The data from Pioneer 11 and Voyager were reviewed, intercompared, and correlated with model predictions to set limits on the matter distribution

Humbler craft: Rafts of the Egyptian Nile, 17th-20th Centuries AD

PublishedArticleWritten accounts and images created by foreign travellers on the Egyptian Nile over the past four centuries indicate the widespread use of rafts and floats for both local and long-distance Nile travel. Many of the materials employed are poor survivors in archaeological deposits, or are otherwise easily overlooked as components of river-craft: moreover, several of these raft types were built for a single season or journey, then dismantled. Well preserved wooden boats belonging to the pharaonic élite have commanded the attention of maritime archaeologists of the Nile. But these traveller accounts alert us to a class of vessels not yet recognized in archaeological deposits, and which point to a humbler quotidian experience of Nile navigation than the royal ships of antiquity.Golden Web FoundationAHR

Egypt’s Nile-Red Sea canals: chronology, location, seasonality and function

© Archaeopress & Hadrian 2009Paper from the conference Connected Hinterlands (Proceedings of Red Sea Project IV) held at the University of Southampton in September 2008

A stone anchor from the Farasan Islands, Saudi Arabia

PublishedArticleA large three-holed stone anchor has been found on the Farasan Islands, Saudi Arabia, in the southern Red Sea. The anchor was found on land, 2.6 km from the coast, on a fossil-coral plateau alongside the Wadi Matar valley. This short article describes the anchor, contextualises the find in terms of the wider archaeology of the islands, considers its likely date, and looks for typological comparisons. The authors tentatively suggest that the anchor is representative of a local or regional nautical technology, and that it is of pre-Islamic dateGolden Web FoundationSeven Pillars of Wisdom TrustSCT

Reparameterizing the Birkhoff Polytope for Variational Permutation Inference

Many matching, tracking, sorting, and ranking problems require probabilistic reasoning about possible permutations, a set that grows factorially with dimension. Combinatorial optimization algorithms may enable efficient point estimation, but fully Bayesian inference poses a severe challenge in this high-dimensional, discrete space. To surmount this challenge, we start with the usual step of relaxing a discrete set (here, of permutation matrices) to its convex hull, which here is the Birkhoff polytope: the set of all doubly-stochastic matrices. We then introduce two novel transformations: first, an invertible and differentiable stick-breaking procedure that maps unconstrained space to the Birkhoff polytope; second, a map that rounds points toward the vertices of the polytope. Both transformations include a temperature parameter that, in the limit, concentrates the densities on permutation matrices. We then exploit these transformations and reparameterization gradients to introduce variational inference over permutation matrices, and we demonstrate its utility in a series of experiments

THE EFFECT OF INFLATION ON PRIVATE CONTRACTS: UNITED STATES, 1861-1879

The Northern inflation coincided almost exactly in its early stages with the inflation in the South, and was produced by the same basic factor - a budgetary deficit due to war expenditure. The financial mobilization of the North was handicapped at the outset by a deficit inherited from the previous administration and by an impaired national credit. The prompt response of the Northern banks enabled the Treasury to overcome this initial handicap and to finance the greatly increased expenditure through the early months of the war. How long orthodox methods of borrowing would have sufficed has been ever since a matter of debate. Toward the end of 1861 the banking system had begun to show signs of serious strain which was greatly aggravated by the policies of Secretary Chase in concentrating at the Treasury a very large share of the supply of specie. The unfavorable state of national finances at the end of the year and the danger of war with England over the Trent affair were enough to produce a panic on December 16 and to force a suspension of specie payments on December 30, 1861

Interpreting Fracture Patterns in Sandstones Interbedded with Ductile Strata at the Salt Valley Anticline, Arches National Park, Utah

Sandstones that overlie or that are interbedded with evaporitic or other ductile strata commonly contain numerous localized domains of fractures, each covering an area of a few square miles. Fractures within the Entrada Sandstone at the Salt Valley Anticline are associated with salt mobility within the underlying Paradox Formation. The fracture relationships observed at Salt Valley (along with examples from Paleozoic strata at the southern edge of the Holbrook basin in northeastern Arizona, and sandstones of the Frontier Formation along the western edge of the Green River basin in southwestern Wyoming), show that although each fracture domain may contain consistently oriented fractures, the orientations and patterns of the fractures vary considerably from domain to domain. Most of the fracture patterns in the brittle sandstones are related to local stresses created by subtle, irregular flexures resulting from mobility of the associated, interbedded ductile strata (halite or shale). Sequential episodes of evaporite dissolution and/or mobility in different directions can result in multiple, superimposed fracture sets in the associated sandstones. Multiple sets of superimposed fractures create reservoir-quality fracture interconnectivity within restricted localities of a formation. However, it is difficult to predict the orientations and characteristics of this type of fracturing in the subsurface. This is primarily because the orientations and characteristics of these fractures typically have little relationship to the regional tectonic stresses that might be used to predict fracture characteristics prior to drilling. Nevertheless, the high probability of numerous, intersecting fractures in such settings attests to the importance of determining fracture orientations in these types of fractured reservoirs

THE EFFECT OF INFLATION ON PRIVATE CONTRACTS: UNITED STATES, 1861-1879

The American Civil War provides ample material for studying the legal consequences of currency depreciation. The sudden demands of war on government budgets made it necessary in both North and South to issue a large volume of paper money, which produced a general rise in prices, a premium on gold, and all the other indices of major monetary inflation. American history had already illustrated the dangers in the use of unstable monetary standards and in too rapid an expansion of the monetary supply. The period of the Civil War is of peculiar interest to lawyers, however, because the record of private litigation is more abundant and because of the different course that inflation took in the two main areas. In the North the depreciation was arrested when the purchasing power of money had been cut to approximately one-half of its pre-war ratio. In the South continued issues of paper money brought progressive depreciation of the currency until its final complete collapse. We have therefore for comparison two great communities, governed by essentially the same legal system, projected side by side through varying degrees of monetary convulsion. From a study of the legal devices employed to meet these emergencies it is possible to derive some conclusions as to the resources of American law in the face of inflation. The limitations on the effectiveness of such devices may also suggest the hazards that face any system of private contract in periods of monetary disturbance

Exact and approximate dynamics of the quantum mechanical O(N) model

We study a quantum dynamical system of N, O(N) symmetric, nonlinear oscillators as a toy model to investigate the systematics of a 1/N expansion. The closed time path (CTP) formalism melded with an expansion in 1/N is used to derive time evolution equations valid to order 1/N (next-to-leading order). The effective potential is also obtained to this order and its properties areelucidated. In order to compare theoretical predictions against numerical solutions of the time-dependent Schrodinger equation, we consider two initial conditions consistent with O(N) symmetry, one of them a quantum roll, the other a wave packet initially to one side of the potential minimum, whose center has all coordinates equal. For the case of the quantum roll we map out the domain of validity of the large-N expansion. We discuss unitarity violation in the 1/N expansion; a well-known problem faced by moment truncation techniques. The 1/N results, both static and dynamic, are also compared to those given by the Hartree variational ansatz at given values of N. We conclude that late-time behavior, where nonlinear effects are significant, is not well-described by either approximation.Comment: 16 pages, 12 figrures, revte