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 first order iteration process for simultaneous equations

First order iteration process for solutions of simultaneous equation

Keystone XL Pipeline Project: Key Issues

[Excerpt] This report describes the Keystone XL pipeline proposal and the process required for federal approval. It summarizes key arguments for and against the pipeline put forth by the pipeline’s developers, federal agencies, environmental groups, and other stakeholders. Finally, the report reviews the constitutional basis for the State Department’s authority to issue a Presidential Permit, and opponents’ possible challenges to this authority

Seasonal cycling of sulfur and iron in porewaters of a Delaware salt marsh

An extensive pore water data set has been gathered in the Great Marsh, Delaware over various seasons, salinities, and tides. The data all point to a complimentary redox cycle for sulfur and iron which operates seasonally and tidally. Surface oxidizing conditions prevail in summer, with more reducing conditions at depth during the winter. During the spring tides which flood the marsh, pyrite oxidation occurs releasing excess dissolved iron (II) and sulfate to the porewaters, and precipitating authigenic solid iron phases. The redox conditions in the porewaters of the upper zone during the summer is poised between mildly oxidizing and mildly reducing conditions as shown by pE calculations. This redox environment and intermediate iron-sulfur redox species may be important for the stimulation of plant growth (photosynthesis) and sustenance of a viable microbial community (heterotrophy and chemoautropy)

Keystone XL Pipeline Project: Key Issues

[Excerpt] This report describes the Keystone XL Project as it is proposed in the 2012 Presidential Permit application and the process that the State Department is obligated to complete to issue or deny that application. To the extent that they may affect the State Department’s decision to issue or deny the current permit application, this report discusses selected issues related to the project proposed in 2008 and issues that have arisen since the State Department denied the initial permit application in 2012. This report also summarizes key arguments that have been raised, both for and against the pipeline, by the pipeline’s developers, state and federal agencies, environmental groups, private property owners, and other stakeholders. Finally, the report discusses the constitutional basis for the State Department’s authority to issue a Presidential Permit, and opponents’ possible challenges to this authority

Conflict of Allegiance

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