The dynamics and excitation of torsional waves in geodynamo simulations

The predominant force balance in rapidly rotating planetary cores is between Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance leads to a Taylor state where the spatially averaged azimuthal Lorentz force is compelled to vanish on cylinders aligned with the rotation axis. Any deviation from this state leads to a torsional oscillation, signatures of which have been observed in the Earth's secular variation and are thought to influence length of day variations via angular momentum conservation. In order to investigate the dynamics of torsional oscillations (TOs), we perform several 3-D dynamo simulations in a spherical shell. We find TOs, identified by their propagation at the correct Alfvén speed, in many of our simulations. We find that the frequency, location and direction of propagation of the waves are influenced by the choice of parameters. Torsional waves are observed within the tangent cylinder and also have the ability to pass through it. Several of our simulations display waves with core traveltimes of 4–6 yr. We calculate the driving terms for these waves and find that both the Reynolds force and ageostrophic convection acting through the Lorentz force are important in driving TOs

Divide-and-conquer: A proportional, minimal-envy cake-cutting algorithm

We analyze a class of proportional cake-cutting algorithms that use a minimal number of cuts (n-1 if there are n players) to divide a cake that the players value along one dimension. While these algorithms may not produce an envy-free or efficient allocation--as these terms are used in the fair-division literature--one, divide-and-conquer (D&C), minimizes the maximum number of players that any single player can envy. It works by asking n ≥ 2 players successively to place marks on a cake--valued along a line--that divide it into equal halves (when n is even) or nearly equal halves (when n is odd), then halves of these halves, and so on. Among other properties, D&C ensures players of at least 1/n shares, as they each value the cake, if and only if they are truthful. However, D&C may not allow players to obtain proportional, connected pieces if they have unequal entitlements. Possible applications of D&C to land division are briefly discussed.mechanism design; fair division; divisible good; cake-cutting; divide-and-choose

N-Person cake-cutting: there may be no perfect division

A cake is a metaphor for a heterogeneous, divisible good, such as land. A perfect division of cake is efficient (also called Pareto-optimal), envy-free, and equitable. We give an example of a cake in which it is impossible to divide it among three players such that these three properties are satisfied, however many cuts are made. It turns out that two of the three properties can be satisfied by a 3-cut and a 4-cut division, which raises the question of whether the 3-cut division, which is not efficient, or the 4-cut division, which is not envy-free, is more desirable (a 2-cut division can at best satisfy either envy-freeness or equitability but not both). We prove that no perfect division exists for an extension of the example for three or more players.Cake-cutting; fair division; efficiency; envy-freeness; equitability; heterogeneous good

Forming Stable Coalitions: The Process Matters

Players are assumed to rank each other as coalition partners. Two processes of coalition formation are defined and illustrated: i) Fallback (FB): Players seek coalition partners by descending lower and lower in their preference rankings until some majority coalition, all of whose members consider each other mutually acceptable, forms. ii) Build-up (BU):Same descent as FB, except only majorities whose members rank each other highest form coalitions. BU coalitions are stable in the sense that no member would prefer to be in another coalition, whereas FB coalitions, whose members need not rank each other highest, may not be stable. BU coalitions are bimodally distributed in a random society, with peaks around simple majority and unanimity the distributions of majorities in the US Supreme Count and in the US House of Representatives follow this pattern. The dynamics of real-life coalition-formation processes are illustrated by two Supreme Court cases.Coalition dynamics, Fallback bargaining, Manipulability, Legislatures, US Supreme Court

Short-term Response of Holcus lanatus L. (Common Velvetgrass) to Chemical and Manual Control at Yosemite National Park, USA

One of the highest priority invasive species at both Yosemite and Sequoia and Kings Canyon national parks is Holcus lanatus L. (common velvetgrass), a perennial bunchgrass that invades mid-elevation montane meadows. Despite velvetgrass being a high priority species, there is little information available on control techniques. The goal of this project was to evaluate the short-term response of a single application of common chemical and manual velvetgrass control techniques. The study was conducted at three montane sites in Yosemite National Park. Glyphosate spotspray treatments were applied at 0.5, 1.0, 1.5, and 2.0% concentrations, and compared with hand pulling to evaluate effects on cover of common velvetgrass, cover of other plant species, and community species richness. Posttreatment year 1 cover of common velvetgrass was 12.1% 6 1.6 in control plots, 6.3% 6 1.5 averaged over the four chemical treatments (all chemical treatments performed similarly), and 13.6% 6 1.7 for handpulled plots. This represents an approximately 50% reduction in common velvetgrass cover in chemically- treated plots recoded posttreatment year 1 and no statistically significant reduction in hand pulled plots compared with controls. However, there was no treatment effect in posttreatment year 2, and all herbicide application rates performed similarly. In addition, there were no significant treatment effects on nontarget species or species richness. These results suggest that for this level of infestation and habitat type, (1) one year of hand pulling is not an effective control method and (2) glyphosate provides some level of control in the short-term without impact to nontarget plant species, but the effect is temporary as a single year of glyphosate treatment is ineffective over a twoyear period

Reducing CO2 Emissions in the Upper Midwest: Technology, Resources, Economics, and Policy

We develop scenarios for reducing carbon dioxide emissions from the electricity sector in the upper Midwest (Wisconsin, Illinois, Minnesota, Iowa, North Dakota, South Dakota, Montana, Wyoming, and Manitoba) by 80% relative to 1990 levels. The report has three major components: 1) an inventory of CO2 emissions from all fossil fuel combustion in the region from 1960-2001, subdividing by economic sector and specific electricity generating station; 2) an evaluation of all electricity resources in the region and all technologies for utilizing them, taking into account the overall scale of the resource, technology costs, and other issues that influence the selection of a certain technology; and 3) the development of a simulation model to examine the impact of various factors (policies, prices, technologies, resources) on the regional electricity supply and its emissions from 2005-2055.Environmental Economics and Policy,

Economically Optimal Distiller Grain Inclusion in Beef Feedlot Rations: Recognition of Omitted Factors

With the rapid expansion of the ethanol industry, the feeding landscape familiar to the feedlot industry is changing. While concerns regarding rising corn prices persist, many within the industry are looking at distiller’s grains, a by-product of ethanol production, to serve as a feed substitute. The question remains as to what extent these two feed sources are substitutable. The purpose of this study is to identify the economically optimal inclusion rate of distiller’s grains in beef feedlot rations, considering an array of often omitted factors. Most currently prevailing recommendation rates are strictly biologically based and frequently reference only one feeding trial. Unique economic factors considered in this research include the impact of by-product inclusion rates on animal performance (utilizing recently conducted meta-analysis from 17 relevant feeding trials), enhanced likelihood of death loss from heightened sulfur content, and manure disposal costs. Results indicate that excluding these factors can significantly impact optimal inclusion levels and that reliance on a single or few feeding trials may greatly bias results.distiller’s grains, livestock rations, manure disposal cost,

Economically Optimal Distiller Grain Inclusion in Beef Feedlot Rations: Recognition of Omitted Factors

With the rapid expansion of the ethanol industry, the feeding landscape familiar to the feedlot industry is changing. While concerns regarding rising corn prices persist, many within the industry are looking at distillers grains, a by-product of ethanol production, to serve as a feed substitute. The question remains as to what extent these two feed sources are substitutable. The purpose of this study is to identify the economically optimal inclusion rate of distillers grains in beef feedlot rations, considering an array of often omitted factors. Most currently prevailing recommendation rates are strictly biologically based and frequently reference only one feeding trial. Unique economic factors considered in this research include the impact of by-product inclusion rates on animal performance (utilizing recently conducted meta-analysis from 17 relevant feeding trials), enhanced likelihood of death loss from heightened sulfur content, and manure disposal costs. Results indicate that excluding these factors can significantly impact optimal inclusion levels and that reliance on a single or few feeding trials may greatly bias results.Livestock Production/Industries,

Straw and Nominee Corporations in Real Estate Tax Shelter Transactions

During 1976, Congress placed some severe restrictions on tax shelter investments. In addition, even before Congress acted, the Internal Revenue Service (IRS) initiated its own attack on tax shelters. One IRS tactic to frustrate the objectives of tax shelter investments is to shift the incidence of taxation from one entity to another. This Article focuses primarily on one phase of the IRS attacks on real estate tax shelters. We will explore the history and legal foundation of the IRS’s present position, outline alternative arguments that can be raised by a real taxpayer involved in an IRS audit, and suggest possible tax planning considerations