Context. The most recent determination of the solar chemical composition by Asplund et al. (2005), using time-dependent, 3D hydrodynamical model of the solar atmosphere, exhibits a significant decrease on C, N, O abundances compared to their previous values. Solar models that use these new abundances are not consistent with helioseismological determinations of the sound speed profile, the surfa...

We derive parameters and abundances of several elements in two cool Pleiades dwarfs, four cool NGC 2264 preÈmain-sequence stars, and a probable NGC 2264 nonmember from high-resolution, moderate signal-to-noise ratio, Keck/HIRES spectra. Our Pleiades Fe abundance agrees with previous spectroscopic and photometric values of hotter stars and does not resolve the 0.3 mag distance modulus discrepanc...

The role of complex life cycles in patterns of estuarine habitat use can be evaluated by studying stage-specific changes in abundances between principal habitats. Here, we evaluated how two primary habitats, tidal freshwater (salinity !3) and brackish water (salinity 3e15), structured juvenile white perch (Morone americana) abundance for eight sub-estuaries of the Chesapeake Bay. In addition, a...

Aims. To determine whether or not gas-phase chemical models with homogeneous and time-independent physical conditions explain the many observed molecular abundances in astrophysical sources, it is crucial to estimate the uncertainties in the calculated abundances and compare them with the observed abundances and their uncertainties. Non linear amplification of the error and bifurcation may limi...

Limits can be placed on nonstandard neutrino physics when big bang nucleosynthesis (BBN) calculations employing standard neutrino physics agree with the observationally inferred primordial abundances of deuterium (D), He, He, and Li. These constraints depend most sensitively on the abundances of D and He. New observational determinations of the primordial D and/or He abundances could force revi...