Coral reefs of north Jamaica, normally sheltered, were severely damaged by Hurricane Allen, the strongest Caribbean hurricane of this century. Immediate studies were made at Discovery Bay, where reef populations were already known in some detail. Data are presented to show how damage varied with the position and orientation of the substraturn and with the shape, size, and mechanical properties of exposed organisms. Data collected over succeeding weeks showed striking differences in the ability of organisms to heal and survive.
he Pierre Auger Observatory, located on a vast, high plain in western\ud
Argentina, is the world's largest cosmic ray observatory. The objectives\ud
of the Observatory are to probe the origin and characteristics of cosmic\ud
rays above 10(17) eV and to study the interactions of these, the most\ud
energetic particles observed in nature. The Auger design features an\ud
array of 1660 water Cherenkov particle detector stations spread over\ud
3000 km(2) overlooked by 24 air fluorescence telescopes. In addition,\ud
three high elevation fluorescence telescopes overlook a 23.5 km(2),\ud
61-detector infilled array with 750 in spacing. The Observatory has been\ud
in successful operation since completion in 2008 and has recorded data\ud
from an exposure exceeding 40,000 km(2) sr yr. This paper describes the\ud
design and performance of the detectors, related subsystems and\ud
infrastructure that make up the Observatory
: Construction of the first stage of the Pierre Auger Observatory has begun. The aim of the Observatory is to collect unprecedented information about cosmic rays above 10(18) eV. The first phase of the project, the construction and operation of a prototype system, known as the engineering array, has now been completed. It has allowed all of the sub-systems that will be used in the full instrument to be tested under field conditions. In this paper, the properties and performance of these sub-systems are described and their success illustrated with descriptions of some of the events recorded thus far. (C) 2003 Elsevier B.V
Using data collected at the Pierre Auger Observatory during the past 3.7 years, we demonstrated a correlation between the arrival directions of cosmic rays with energy above 6 x 10(19) electron volts and the positions of active galactic nuclei (AGN) lying within approximately 75 megaparsecs. We rejected the hypothesis of an isotropic distribution of these cosmic rays with at least a 99% confidence level from a prescribed a priori test. The correlation we observed is compatible with the hypothesis that the highest-energy particles originate from nearby extragalactic sources whose flux has not been substantially reduced by interaction with the cosmic background radiation. AGN or objects having a similar spatial distribution are possible sources.
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