Evolution of the 1.4 GHz Radio Luminosity Function

The results of an optical and infrared investigation of a complete sub-sample of the Leiden-Berkeley Deep Survey (flux > 1 mJy at 1.4 GHz) are presented. Optical counterparts have been identified for 69 of the 73 sources in the two Hercules fields, and redshifts obtained for 49 of them. Photometric redshifts are computed from the g,r,i,K data for the remaining 21 sources. This complete sample is compared with the radio luminosity functions (RLFs) of Dunlop and Peacock (1990). The RLF models successfully trace the evolution of the radio sources with redshift, but there is some disagreement between the luminosity-dependence of the models and the data. The observed RLF for the lower luminosity population (log P < 26) shows evidence for a cut-off at lower redshifts (z=0.5-1.5) than for the more powerful objects.Comment: To appear in "After the Dark Ages: When Galaxies Were Young (the Universe at 2 < z < 5)", University of Maryland, October 1998, S. S. Holt and E. P. Smith (eds), (AIP), 4 pages, 4 figures, uses aipproc.sty and epsfig.st

The chemical composition and energy content of the energetic cosmic radiation

A brief survey is made of our present knowledge of the composition and energy spectra of the primary cosmic radiation. The total energy carried by all forms of cosmic radiation that have appreciable penetrability into matter has been evaluated

Logic controlled solid state switchgear

Logic controlled solid state circuit breakers and power transfer switches have been designed and built to demonstrate their use for 270 V dc power systems. This switchgear provides remote operation, automatic current level, and operates several orders of magnitude faster with much greater accuracy of response than conventional switchgear

Construction noise database (phase 3): Evaluation of established measurement protocol

Executive Summary 1.1 The established method for obtaining noise emission data for the update of a database of noise from construction plant is examined. 1.2 The established measurement protocol involves the collection of plant noise measurements using a sound level meter, and the normalisation of the data to 10m. 1.3 The results of analytical and experimental investigations conclude that this measurement protocol is reasonably accurate and a practical method for the characterisation of plant sound power on-site for both stationary and dynamic activities