Mining in Alaska - environmental impact and pollution control

Environmental factors affecting mining are difficult to establish in Alaska due to the absence of large scale hard rock mining activities at the present time. Currently, experience is gathered from (and to a large degree based on) construction of above ground facilities such as roads, pipelines, and buildings. Past mining activities appear to have had little lasting effect on the natural environment, the exceptions being mine tailings and surface structures. This report, sponsored by the U. S. Bureau of Mines, present general engineering activities, considers the interaction of permafrost and underground mining, summarizes available literature and indicates possible environmental problems that might be encountered in Alaska based on Scandinavian experiences in large-scale northern mining operations. How the Scandinavians are solving their problems is also discussed.This paper was sponsored by the U. S. Bureau of Mines, Contract No. 0133059.Abstract -- Acknowledgements -- Table of contents -- List of illustrations -- List of tables -- Introduction -- Climatic parameters -- Alaska climatic regions -- Construction and mining activities in the Arctic -- General -- Cold weather construction practices -- Permafrost and underground mining operations -- Environmental considerations -- Mining and exploration parameters -- Conclusions -- Recommendations -- Bibliography -- Appendices -- Appendix A: Bibliography - Lost River area -- Appendix B: Mining and environmental considerations as practiced in Norway and Sweden -- Appendix C: Mining vs. the environment -- Figure 1. Alaska climatic regions -- Figure 2. Index map showing mining districts examined -- List of tables -- Table 1. Dates of break-up and freeze-up

Planetesimal Formation with Particle Feedback

Proposed mechanisms for the formation of km-sized solid planetesimals face long-standing difficulties. Robust sticking mechanisms that would produce planetesimals by coagulation alone remain elusive. The gravitational collapse of smaller solids into planetesimals is opposed by stirring from turbulent gas. This proceeding describes recent works showing that "particle feedback," the back-reaction of drag forces on the gas in protoplanetary disks, promotes particle clumping as seeds for gravitational collapse. The idealized streaming instability demonstrates the basic ability of feedback to generate particle overdensities. More detailed numerical simulations show that the particle overdensities produced in turbulent flows trigger gravitational collapse to planetesimals. We discuss surprising aspects of this work, including the large (super-Ceres) mass of the collapsing bound cluster, and the finding that MHD turbulence aids gravitational collapse.Comment: 6 pages, to appear in ``Extreme Solar Systems'', D. Fischer, F. Rasio, S. Thorsett and A. Wolszczan (eds), ASP Conf. Ser., 200

Exclusivity and Bidding for Premium Broadcasting Rights

Often, we observe that some TV channels are distributed on several platforms, and by several distributors on the same platform, while others are distributed exclusively by one distributor. In this paper, we analyse a TV channelel's incentives for choosing exclusive distribution versus full distribution. We then proceed by studying if bidding for premium content (e.g., broadcasting rights to football) influences the incentives for choosing exclusive distribution. We show that absent of premium content, the channel has incentives to choose exclusive distribution, but the existence of premium con- tent dramatically reduces these incentives, and full distribution is the likely outcome.Exclusive dealing; auctions; football; media.

Global magnetohydrodynamical models of turbulence in protoplanetary disks I. A cylindrical potential on a Cartesian grid and transport of solids

We present global 3D MHD simulations of disks of gas and solids, aiming at developing models that can be used to study various scenarios of planet formation and planet-disk interaction in turbulent accretion disks. A second goal is to show that Cartesian codes are comparable to cylindrical and spherical ones in handling the magnetohydrodynamics of the disk simulations, as the disk-in-a-box models presented here develop and sustain MHD turbulence. We investigate the dependence of the magnetorotational instability on disk scale height, finding evidence that the turbulence generated by the magnetorotational instability grows with thermal pressure. The turbulent stresses depend on the thermal pressure obeying a power law of 0.24+/-0.03, compatible with the value of 0.25 found in shearing box calculations. The ratio of stresses decreased with increasing temperature. We also study the dynamics of boulders in the hydromagnetic turbulence. The vertical turbulent diffusion of the embedded boulders is comparable to the turbulent viscosity of the flow. Significant overdensities arise in the solid component as boulders concentrate in high pressure regions.Comment: Changes after peer review proces

Magnetostrictive behaviour of thin superconducting disks

Flux-pinning-induced stress and strain distributions in a thin disk superconductor in a perpendicular magnetic field is analyzed. We calculate the body forces, solve the magneto-elastic problem and derive formulas for all stress and strain components, including the magnetostriction $\Delta R/R$. The flux and current density profiles in the disk are assumed to follow the Bean model. During a cycle of the applied field the maximum tensile stress is found to occur approximately midway between the maximum field and the remanent state. An effective relationship between this overall maximum stress and the peak field is found.Comment: 8 pages, 6 figures, submitted to Supercond. Sci. Technol., Proceed. of MEM03 in Kyot

New Paradigms For Asteroid Formation

Asteroids and meteorites provide key evidence on the formation of planetesimals in the Solar System. Asteroids are traditionally thought to form in a bottom-up process by coagulation within a population of initially km-scale planetesimals. However, new models challenge this idea by demonstrating that asteroids of sizes from 100 to 1000 km can form directly from the gravitational collapse of small particles which have organised themselves in dense filaments and clusters in the turbulent gas. Particles concentrate passively between eddies down to the smallest scales of the turbulent gas flow and inside large-scale pressure bumps and vortices. The streaming instability causes particles to take an active role in the concentration, by piling up in dense filaments whose friction on the gas reduces the radial drift compared to that of isolated particles. In this chapter we review new paradigms for asteroid formation and compare critically against the observed properties of asteroids as well as constraints from meteorites. Chondrules of typical sizes from 0.1 to 1 mm are ubiquitous in primitive meteorites and likely represent the primary building blocks of asteroids. Chondrule-sized particles are nevertheless tightly coupled to the gas via friction and are therefore hard to concentrate in large amounts in the turbulent gas. We review recent progress on understanding the incorporation of chondrules into the asteroids, including layered accretion models where chondrules are accreted onto asteroids over millions of years. We highlight in the end ten unsolved questions in asteroid formation where we expect that progress will be made over the next decade.Comment: Chapter to appear in the book ASTEROIDS IV, (University of Arizona Press) Space Science Series, edited by P. Michel, F. DeMeo and W. Bottk

A Comparison of Costs and Returns for Organic and Conventional Cabernet Sauvignon Grape Production in San Luis Obispo County

This study examined the differences in costs and profitability for established conventional and organic Cabernet Sauvignon vineyards in the Edna Valley region of San Luis Obispo County, California. The study used a partial budgeting approach to compare cost and profitability for established vineyards for 2009, and thus ignored transition costs. Data were obtained from UC Davis cost studies for organic and conventional grape production in other regions of California in previous years. Adjustments made to these costs to account for changes in input use, input costs and grape prices in San Luis Obispo County during the 2009 growing season. The basic costs were found the conventional costs were slightly higher than the organic, however with the partial budget change it was deemed ‘unfeasible’. The study found that the profitability of established vineyards would be equal with a price premium of 1.08%. There were many limitations and estimations when doing this study such as secondary information and use of price indexing; therefore the price premium may be more or less depending on the vineyard

Evidence of discrete scale invariance in DLA and time-to-failure by canonical averaging

Discrete scale invariance, which corresponds to a partial breaking of the scaling symmetry, is reflected in the existence of a hierarchy of characteristic scales l0, c l0, c^2 l0,... where c is a preferred scaling ratio and l0 a microscopic cut-off. Signatures of discrete scale invariance have recently been found in a variety of systems ranging from rupture, earthquakes, Laplacian growth phenomena, ``animals'' in percolation to financial market crashes. We believe it to be a quite general, albeit subtle phenomenon. Indeed, the practical problem in uncovering an underlying discrete scale invariance is that standard ensemble averaging procedures destroy it as if it was pure noise. This is due to the fact, that while c only depends on the underlying physics, l0 on the contrary is realisation-dependent. Here, we adapt and implement a novel so-called ``canonical'' averaging scheme which re-sets the l0 of different realizations to approximately the same value. The method is based on the determination of a realization-dependent effective critical point obtained from, e.g., a maximum susceptibility criterion. We demonstrate the method on diffusion limited aggregation and a model of rupture.Comment: 14 pages, 6 figures, in press in Int. J. Mod. Phys.