Nitrogen and phosphorus budgets for the central Great Barrier Reef Shelf

Shelf-scale budgets were developed for the nutrient elements nitrogen (N) and phosphorus (P) in the central Great Barrier Reef between Cape Tribulation (I 60 S} and Dunk Island (ca. 18°S). The intent was to quantify: I} stocks of nutrients (nitrogen (N). phosphorus (P) and silicon (Si}) naturally occurring in central Great Barrier Reef waters; 2) natural gradients and variability in water column nutrient concentrations; 3} natural fluxes of nutrients into and out of shelf waters for comparison with anthropogenic or anthropogenically affected nutrient sources

Dissolved and particulate nutrients in waters of the Whitsunday Island Group 1988

This report summarizes the results of hydrographic sampling of physical properties and nutrient determinations made on water samples and water column particulate matter collected in February. 1988 during an oceanographic survey through the Whitsunday Island group. The survey was carried out to obtain background data on concentrations of chlorophyll, organic and inorganic nitrogen (N). phosphorus (P), and inorganic silicate (Si) in waters of the Whitsunday Island group. For comparative purposes, hydrographic and nutrient data from ten stations occupied in inter-reefal and lagoonal waters of the central and southern GBR during January. 1987 and February, 1988 are also presented

Isospin-Violating Meson-Nucleon Vertices as an Alternate Mechanism of Charge-Symmetry Breaking

We compute isospin-violating meson-nucleon coupling constants and their consequent charge-symmetry-breaking nucleon-nucleon potentials. The couplings result from evaluating matrix elements of quark currents between nucleon states in a nonrelativistic constituent quark model; the isospin violations arise from the difference in the up and down constituent quark masses. We find, in particular, that isospin violation in the omega-meson--nucleon vertex dominates the class IV CSB potential obtained from these considerations. We evaluate the resulting spin-singlet--triplet mixing angles, the quantities germane to the difference of neutron and proton analyzing powers measured in elastic $\vec{n}-\vec{p}$ scattering, and find them commensurate to those computed originally using the on-shell value of the $\rho$-$\omega$ mixing amplitude. The use of the on-shell $\rho$-$\omega$ mixing amplitude at $q^2=0$ has been called into question; rather, the amplitude is zero in a wide class of models. Our model possesses no contribution from $\rho$-$\omega$ mixing at $q^2=0$, and we find that omega-meson exchange suffices to explain the measured $n-p$ analyzing power difference~at~183 MeV.Comment: 20 pages, revtex, 3 uuencoded PostScript figure

Rho-omega Mixing and the Pion Electromagnetic Form-Factor

The suggestion of momentum dependence in the amplitude for rho-omega mixing has generated concern over related implications for vector meson dominance and the photon-rho coupling. We discuss two established representations of vector meson dominance and show that one of these is completely consistent with such a coupling. We then apply it to a calculation of the pion electromagnetic form-factor. Our analysis leads to a new value for the on-shell rho-omega mixing amplitude of (-3800 +/- 370) MeV^2.Comment: 11 pages with epsfig.sty. Publication details added to title pag