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

Continued DDT Persistence in Mississippi River Delta Streams: A Case Study

Fish samples representative of several trophic levels were taken from the Wolf and Loosahatchie Rivers of western Tennessee during the early 1980s. Results indicate that DDT, with metabolites DDD and DDE, remains common in fish tissues in these areas and approaches the levels recommended as maxima for human consumption by the U.S. Food and Drug Administration. Samples of top carnivores and forage fishes, particularly the gizzard shad, Dorosoma cepedlanum, commonly exceeded 500 ppb DDE. The results are discussed in light of sediment disturbing activities

Acceleration of Wound Healing with High Voltage, Monophasic, Pulsed Current

The purpose of this study was to determine whether high voltage electrical stimulation accelerates the rate of healing of dermal ulcers. Sixteen patients with stage IV decubitus ulcers, ranging in age from 20 to 89 years, participated in the study. The patients were assigned randomly to either a Treatment Group (n = 9) or a Control Group (n = 7). Patients in the Treatment Group received daily electrical stimulation from a commercial high voltage generator. Patients in the Control Group had the electrodes applied daily but received no stimulation. The ulcers of patients in the Treatment Group healed at a mean rate of 44.8% a week and healed 100% over a mean period of 7.3 weeks. The ulcers of patients in the Control Group increased in area an average of 11.6% a week and increased 28.9% over a mean period of 7.4 weeks. The results of this study suggest that high voltage stimulation accelerates the healing rate of stage IV decubitus ulcers in human subjects

A Third-order and a Fourth-order Iteration Process for Nonlinear Equations

Convergence proof and procedure for third-order and fourth-order iteration process for nonlinear equations - Newton-Raphson second-order iteratio

ALTERNATIVES FOR SMALL FARM SURVIVAL: GOVERNMENT POLICIES VERSUS THE FREE MARKET

This paper briefly outlines a topology of small farms and then considers the role of the government versus the market in key public policies such as commodity income support, environment, stability, research, and rural development. A number of options are explored for public policy to better serve small farms, including drastic alternatives such as graduated property taxes on farmland, with exemptions or lower rates for small farms. These and other alternatives are not necessarily recommended. Improved extension education and human resource development offer some of the most promising public policy opportunities to help small farmers.Government, Limited resource, Market, Programs, Research, Rural, Scale, Small farm, Farm Management,

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 first order iteration process for simultaneous equations

First order iteration process for solutions of simultaneous equation

Scaling Properties of the Two-Chain Model

Scaling properties of a self-dual field-theoretical model, describing two weakl$spinless Luttinger chains, are studied. A crossover to a sine-Gordon massive phase, with strongly developed two-particleinterchain correlations, is described. It is argued that, in a wide range of the in-chain interaction, renormalization of the interchain hopping amplitude is determined by the Luttinger liquid effects.Comment: 14 pages Latex, accepted Physics Letters

Adjacent face scattering of electrons on a square Fermi surface

Interacting electrons with a square Fermi surface is investigated from a bosonic point of view taking into account electron scattering between all faces of the square. Fermion operators are classified according to their dimensions and the stability of the boson fixed-point is investigated. In particular we find, in contrast to previous studies, that the square Fermi surface is unstable to doping in the case of no spin gap and microscopic Hubbard interactions.Comment: Revtex 6 pages, 1 Figur

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 /