Using the empirical Bayes method to estimate and evaluate bycatch rates of seabirds from individual fishing vessels

Minimizing bycatch of seabirds is a major goal of the U.S. National Marine Fisheries Service. In Alaska waters, the bycatch (i.e., inadvertent catches) of seabirds has been an incidental result of demersal groundfish longline fishery operations. Notably, the endangered short-tailed albatross (Phoebastria albatrus) has been taken in this groundfish fishery. Bycatch rates of seabirds from individual vessels may be of particular interest because vessels with high bycatch rates may not be functioning effectively with seabird avoidance gears, and there may be a need for suggestions on how to use these avoidance gears more effectively. Therefore, bycatch estimates are usually made on an individual vessel basis and then summed to obtain the total estimate for the entire fleet

Enhanced coherent dynamics near a transition between neutral quantum-paraelectric and ionic ferroelectric phases in the quantum Blume-Emery-Griffiths model

Nonequilibrium dynamics are studied near the quantum phase transition point in the one-dimensional quantum Blume-Emery-Griffiths model. Its pseudo-spin component $S^z$ represents an electric polarization, and $(S^z)^2$ corresponds to ionicity, in mixed-stack charge-transfer complexes that exhibit a transition between neutral quantum-paraelectric and ionic ferroelectric (or antiferroelectric) phases. The time-dependent Schr\"odinger equation is solved for the exact many-body wave function in the quantum paraelectric phase. After impact force is introduced on a polarization locally in space and time, polarizations and ionicity coherently oscillate. The oscillation amplitudes are large near the quantum phase transition point. The energy supplied by the impact flows linearly into these oscillations, so that the nonequilibrium behavior is uncooperative.Comment: 6 pages, 4 figures, accepted for publication in Phys. Rev.

Adiabatic connection between the RVB State and the ground state of the half filled periodic Anderson model

A one-parameter family of models that interpolates between the periodic Anderson model with infinite repulsion at half-filling and a model whose ground state is exactly the Resonating-Valence-Bond state is studied. It is shown numerically that the excitation gap does not collapse. Therefore the ground states of the two models are adiabatically connected.Comment: 6 pages, 3 figures Revte

A level-one representation of the quantum affine superalgebra \U_q(\hat{\frak{sl}}(M+1|N+1))

A level-one representation of the quantum affine superalgebra \U_q(\hat{\frak{sl}}(M+1|N+1)) and vertex operators associated with the fundamental representations are constructed in terms of free bosonic fields. Character formulas of level-one irreducible highest weight modules of \U_q(\hat{\frak{sl}}(2|1)) are conjectured.Comment: AMS-TeX, 11 page

Parameterizing probabilities for estimating age-composition distributions for mixture models

When estimating parameters that constitute a discrete probability distribution {pj}, it is difficult to determine how constraints should be made to guarantee that the estimated parameters { pˆj} constitute a probability distribution (i.e., pˆj>0, Σ pˆj =1). For age distributions estimated from mixtures of length-at-age distributions, the EM (expectationmaximization) algorithm (Hasselblad, 1966; Hoenig and Heisey, 1987; Kimura and Chikuni, 1987), restricted least squares (Clark, 1981), and weak quasisolutions (Troynikov, 2004) have all been used. Each of these methods appears to guarantee that the estimated distribution will be a true probability distribution with all categories greater than or equal to zero and with individual probabilities that sum to one. In addition, all these methods appear to provide a theoretical basis for solutions that will be either maximum-likelihood estimates or at least convergent to a probability distribu