Saturn's Icy Moon Rhea: a Prediction for Bulk Chemical Composition and Physical Structure at the Time of the Cassini Spacecraft First Flyby

I report a model for the formation of Saturn's family of mid-sized icy moons to coincide with the first flypast of Rhea by the Cassini Orbiter spacecraft on 26 November 2005. It is proposed that these moons had condensed from a concentric family of orbiting gas rings that were cast off some 4600 Myr ago by the contracting proto-Saturnian cloud. Numerical and structural models for Rhea are constructed on the basis of a computed bulk chemical mix of hydrated rock (mass fraction 0.385), H2O ice (0.395), and NH3 ice (0.220). The large proportion of NH3 in the ice mass inhibits the formation of the dense crystalline phase II of H2O ice at the satellite's centre. This may explain the absence of compressional features on the surface. The favoured model of Rhea has a chemically uniform interior and is very cold. The satellite is nearly isodense and the predicted value of the axial moment-of-inertia factor is C/MR^2 = 0.399 +/- 0.004. NH3 is unstable at Saturn's distance from the Sun, except near the polar regions of the satellite. Perhaps the Cassini Orbiter will discover indirect evidence for NH3 through the sublimative escape of this ice from the outer layers, especially near the equatorial zones. Wasting of NH3 would weaken the residual soil, so making the edges of craters soft and prone to landslides. It will be exciting to learn what Cassini discovers.Comment: This paper was submitted to the Publications of the Astronomical Society of Australia (PASA) on 30 November 200

Macronutrients as sources of food energy.

This background paper considers the extent to which the development of new recommendations for dietary energy requirements needs to account for the macronutrient (fat, carbohydrate, protein and alcohol) profiles of different diets. The issues are discussed from the dual perspectives of avoiding under-nutrition and obesity. It is shown that, in practice, human metabolic processes can adapt to a wide range of fuel supply by altering fuel selection. It is concluded that, at the metabolic level, only diets with the most extreme macronutrient composition would have any consequences by exceeding the natural ability to modify fuel selection. However, diets of different macronutrient composition and energy density can have profound implications for innate appetite regulation and hence overall energy consumption

The origins of American industrial success: Evidence from the US portland cement industry

The contributions of innovations, factor endowments and institutions to American industrialization are examined through analysing the rise of the American portland cement industry. Minerals abundance contributed in multiple ways to the spectacular rise of the industry from the 1890s. However, the results of a structural econometric analysis of entry suggests geological surveys, institutions highlighted by David and Wright, played a contributing rather than critical role in the American portland cement industry overcoming incumbent European portland cement and American natural cement producers.American Economic History; Empirical Industrial Organization; Portland Cement

A micro-econometric model of a short run cost function with unobserved heterogeneity

Unobserved plant level heterogeneity and discrete production processes can produce problems for estimation. A structural model of discrete production decisions by heterogeneous plants is constructed and, as a case study, estimated for the U.S. Portland cement industry. A new estimator is proposed to handle the discrete production process – for which the ordered probit is a special case. Data on firm survival and exit are used to adjust all input requirement coefficients for unobserved heterogeneity. The structural model is successfully estimated. Differences between many estimated coefficients and independent estimates from external sources are statistically insignificant.marginal cost; portland cement; ordered probit

Nystrom Methods in the RKQ Algorithm for Initial-value Problems

We incorporate explicit Nystrom methods into the RKQ algorithm for stepwise global error control in numerical solutions of initial-value problems. The initial-value problem is transformed into an explicitly second-order problem, so as to be suitable for Nystrom integration. The Nystrom methods used are fourth-order, fifth-order and 10th-order. Two examples demonstrate the effectiveness of the algorithm.Comment: This is an extension of ideas published in J. Math. Res. (open access); see refs [1] and [2

Gateways, Corridors and Strategic City Pairs

Advances in transportation technology may mean that topography matters less, but trade routes will continue to favour the paths of least resistance. The location of gateway cities and distribution hubs exhibit patterns of hierarchical systems. A change in technology that alters location advantage heightens corridor competition and in the longer term, it may modify the relative positions of cities in the regional hierarchy. Changes in transportation technology during the 1850s and the 1950s that altered the barriers of time and space reordered trade corridors in these periods. As the 21st Century opens, the growing Asian economies are stimulating Pacific trade routes, and intermodal container shipping is causing a resurgence of railway opportunities for trade routes that are prepared to foster their development. This paper examines the concept of gateways and corridors, and the importance that strategic city pairs play in taking advantage of transportation opportunities. Its purpose is to encourage discussion on the topic of trade corridor competition. The first section presents a conceptual framework for examining trade corridors. Subsequently, two examples of strategic city pairs and corridor competition are considered. The paper concludes with some thoughts on the role of strategic city pairs in the promotion of the Mid-continent corridor.corridors; gateways; strategic partnership