Search

Your search keyword '"Kelleher D"' showing total 1,254 results
Start Over Author "Kelleher D"
1,254 results on '"Kelleher D"'

206. Redistribution of radiation in the absence of collisions

Author

Lombardi, G. G, Kelleher, D. E, and Cooper, J

Subjects
Astrophysics
Abstract

Redistribution and depolarization of near-resonant radiation is studied for the He 2(1P)-3(1D) line (668 nm) and some data for H-alpha (656 nm) are also presented. A Nd:YAG pumped dye laser, with a bandwidth of 0.1/cm and a power density of 100 kW/sq cm, is used in the experiment. The transitions have lower levels with natural line widths that are large compared with their upper-level natural widths, and, under experimental conditions, their collisional widths are also small. The ratio of fluorescence to Rayleigh intensity is measured and the results indicate that while the Rayleigh emission has the same temporal development as the laser pulse (5 ns FWHM), the fluorescent intensity has a decay time determined by the radiative decay lifetime and by collisional quenching. The prediction that redistribution of radiation occurs in the absence of collisions for transitions having significant lower-level radiative widths is confirmed. Depolarization rates by collisions with helium are also inferred from the measurements.

Published
1985
Full Text
View/download PDF

213. The Irish in Britain

Author

Gaffney, Marie, Tilki, M., Lovett, B., Scanlon, K., Hutton, S., Cahill, G., Aspinall, Peter J., Kelleher, D., Gaffney, Marie, Tilki, M., Lovett, B., Scanlon, K., Hutton, S., Cahill, G., Aspinall, Peter J., and Kelleher, D.

Published
2000

214. GAPS IN THE SPECTRUM OF THE LAPLACIAN ON 3N-GASKETS.

Author

KELLEHER, D., GUPTA, N., MARGENOT, M., MARSH, J., OAKLEY, W., and TEPLYAEV, A.

Subjects
POLYNOMIALS, LAPLACIAN operator, GEODESIC equation, DIFFERENTIAL operators, GEODESICS
Abstract

This article develops analysis on fractal 3N-gaskets, a class of post-critically finite fractals which include the Sierpinski triangle for N = 1, specifically properties of the Laplacian Δ on these gaskets. We first prove the existence of a self-similar geodesic metric on these gaskets, and prove heat kernel estimates for this Laplacian with respect to the geodesic metric. We also compute the elements of the method of spectral decimation, a technique used to determine the spectrum of post-critically finite fractals. Spectral decimation on these gaskets arises from more complicated dynamics than in previous examples, i.e. the functions involved are rational rather than polynomial. Due to the nature of these dynamics, we are able to show that there are gaps in the spectrum. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

215. Article 8

Author

Stineman, M., primary, Kurz, A.E., additional, Kelleher, D., additional, and Kennedy, B., additional

Published
2006
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results