89 research outputs found
Correlation energy of an electron gas: a functional approach
Correlation effects of an electron gas in an external potential are derived
using an Effective Action functional method. Corrections beyond the random
phase approximation (RPA) are naturally incorporated by this method. The
Effective Action functional is made to depend explicitly on two-point
correlation functions. The calculation is carried out at imaginary time. For a
homogeneous electron gas, we calculate the effect of exchange on the ring
diagrams at zero temperature and show how to include some of the ladder
diagrams. Our results agree well with known numerical calculations. We conclude
by showing that this method is in fact a variant of the time dependent density
functional method and suggest that it is suitable to be applied to the study of
correlation effects in the non-homogeneous case.Comment: 20 figures numbered as in the tex
Electron heating by sheaths in radio frequency discharges
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A framework for modeling the cathode fall illustrated with a single beam model
This material is presented to ensure timely dissemination of scholarly and technical work. Copyright and all rights therein are retained by authors or by other copyright holders. All persons copying this information are expected to adhere to the terms and constraints invoked by each author's copyright. In most cases, these works may not be reposted without the explicit permission of the copyright holder
The association between rheumatoid arthritis and periodontal disease
Chronic, plaque-associated inflammation of the gingiva and the periodontium are among the most common oral diseases. Periodontitis (PD) is characterized by the inflammatory destruction of the periodontal attachment and alveolar bone, and its clinical appearance can be influenced by congenital as well as acquired factors. The existence of a rheumatic or other inflammatory systemic disease may promote PD in both its emergence and progress. However, there is evidence that PD maintains systemic diseases. Nevertheless, many mechanisms in the pathogenesis have not yet been examined sufficiently, so that a final explanatory model is still under discussion, and we hereby present arguments in favor of this. In this review, we also discuss in detail the fact that oral bacterial infections and inflammation seem to be linked directly to the etiopathogenesis of rheumatoid arthritis (RA). There are findings that support the hypothesis that oral infections play a role in RA pathogenesis. Of special importance are the impact of periodontal pathogens, such as Porphyromonas gingivalis on citrullination, and the association of PD in RA patients with seropositivity toward rheumatoid factor and the anti-cyclic citrullinated peptide antibody
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