APPROACH A: SUBSIDIZING CONSUMPTION AT HOME AND ABROAD

Agricultural and Food Policy,

Interacting Electrons on a Square Fermi Surface

Electronic states near a square Fermi surface are mapped onto quantum chains. Using boson-fermion duality on the chains, the bosonic part of the interaction is isolated and diagonalized. These interactions destroy Fermi liquid behavior. Non-boson interactions are also generated by this mapping, and give rise to a new perturbation theory about the boson problem. A case with strong repulsions between parallel faces is studied and solved. There is spin-charge separation and the square Fermi surface remains square under doping. At half-filling, there is a charge gap and insulating behavior together with gapless spin excitations. This mapping appears to be a general tool for understanding the properties of interacting electrons on a square Fermi surface.Comment: 25 pages, Nordita preprint 94/22

A Hawk-Dove game in kleptoparasitic populations

Kleptoparasitism, the parasitism by theft, is a widespread biological phenomenon. In this paper we extend earlier models to investigate a population of conspecifics involved in foraging and, potentially, kleptoparasitism. We assume that the population is composed of two types of individuals, Hawks and Doves. The types differ according to their strategic choices when faced with an opportunity to steal and to resist a challenge. Hawks use every opportunity to steal and they resist all challenges. Doves never resist and never steal. The fitness of each type of individual depends upon various natural parameters, for example food density, the handling time of a food item, density of the population, as well as the duration of potential fights over the food. We find the Evolutionarily Stable States (ESSs) for all arameter combinations and show that there are three possible ESSs, pure Hawks, pure Doves, and a mixed population of Hawks and Doves. We show that for any set of parameter values there is exactly one ESS. We further investigate the relationship between our findings and the classical Hawk-Dove game as defined in Maynard Smith 1982. We also show how our model extends the classical on

A method of hardware qualification for flight by analyses, similarity and integrated testing

The results are described of a study on four pieces of flight hardware from the Saturn 1U and S-4B stages to determine whether the objectives of the formal qualification tests on that hardware could have been obtained within that program by methods other than performing the qualification tests. These methods include qualification by analyses, similarity and integrated testing, i.e., distribution of the objectives among the other tests in the program. It was found that it is feasible to delete the requirements for formal qualification testing provided that it is accomplished early in the program to allow adequate planning for accomplishing the qualification objectives by other means. Additionally, a scorekeeping system was defined that is simple, straightforward, easy to implement. This scorekeeping system provides complete visibility of equivalent qualification status at any point during the program. A set of groundrules for implementing this study was established as a result of findings on the specific items of hardware studied

Matrix methods for calculating zeros, coefficients, Christoffel numbers, and derivatives of some orthogonal polynomials

Jacobi matrix method for calculating zeros, coefficients, Christoffel numbers, and derivatives of orthogonal polynomial

A scale-model room as a practical teaching experiment

A practical experiment is described which was used to help university students increase their understanding of the effect of construction methods and window design on passive solar heating and electrical heating. A number of one tenth scale model rooms were constructed by students and sited out-of-doors in the late autumn. The models were fabricated to mimic available commercial construction techniques with careful consideration being given to window size and placement for solar access. Each model had a thermostatically controlled electric heating element. The temperatures and electricity use of the models were recorded using data-loggers over a two week period. The performances of the models based on energy consumption and internal temperature were compared with each other and with predictions based upon thermal mass and R-values. Examples of questions used by students to facilitate this process are included. The effect of scaling on thermal properties was analysed using Buckingham&rsquo;s p-theorem.<br /

Note on Review of Dr. Thompson's Occupational Diseases

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