Observing Conditions for Submillimeter Astronomy

Consistently superb observing conditions are crucial for achieving the scientific objectives of a telescope. Submillimeter astronomy is possible only at a few exceptionally dry sites, notably Mauna Kea, the Antarctic plateau, and the Chajnantor region in the high Andes east of San Pedro de Atacama in northern Chile. Long term measurements of 225 GHz and 350 \mu m atmospheric transparency demonstrate all three locations enjoy significant periods of excellent observing conditions. Conditions on the Chajnantor plateau and at the South Pole are better more often than on Mauna Kea. Conditions are better during winter and at night. Near the summit of Cerro Chajnantor, conditions are better than on the Chajnantor plateau

Oriented Quantum Algebras and Coalgebras, Invariants of Oriented 1-1 Tangles, Knots and Links

In this paper we study oriented quantum coalgebras which are structures closely related to oriented quantum algebras. We study the relationship between oriented quantum coalgebras and oriented quantum algebras and the relationship between oriented quantum coalgebras and quantum coalgebras. We show that there are regular isotopy invariants of oriented 1-1 tangles and of oriented knots and links associated to oriented and twist oriented quantum coalgebras respectively. There are many parallels between the theory of oriented quantum coalgebras and the theory of quantum coalgebra

Oriented Quantum Algebras and Invariants of Knots and Links

In GT/0006019 oriented quantum algebras were motivated and introduced in a natural categorical setting. Invariants of knots and links can be computed from oriented quantum algebras, and this includes the Reshetikhin-Turaev theory for Ribbon Hopf algebras. Here we continue the study of oriented quantum algebras from a more algebraic perspective, and develop a more detailed theory for them and their associated invariants.Comment: LAteX document, 45 pages, 17 figure