Anisotropic Bose-Einstein condensates and completely integrable dynamical systems

A Gaussian ansatz for the wave function of two-dimensional harmonically trapped anisotropic Bose-Einstein condensates is shown to lead, via a variational procedure, to a coupled system of two second-order, nonlinear ordinary differential equations. This dynamical system is shown to be in the general class of Ermakov systems. Complete integrability of the resulting Ermakov system is proven. Using the exact solution, collapse of the condensate is analyzed in detail. Time-dependence of the trapping potential is allowed

Chaetopterid tubes from vent and seep sites: Implications for fossil record and evolutionary history of vent and seep annelids

Vestimentiferan tube worms living at deep-sea hydrothermal vents and cold seeps have been considered as a clade with a long and continuing evolutionary history in these ecosystems. Whereas the fossil record appears to support this view, molecular age estimates do not. The two main features that are used to identify vestimentiferan tubes in the fossil record are longitudinal ridges on the tube's surface and a tube wall constructed of multiple layers. It is shown here that chaetopterid tubes from modern vents and seeps—as well as a number of fossil tubes from shallow-water environments—also show these two features. This calls for a more cautious interpretation of tubular fossils from ancient vent and seep deposits. We suggest that: current estimates for a relatively young evolutionary age based on molecular clock methods may be more reliable than the inferences of ancient “vestimentiferans” based on putative fossils of these worms; not all of these putative fossils actually belong to this group; and that tubes from fossil seeps should be investigated for chitinous remains to substantiate claims of their potential siboglinid affinities

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

New molluscs associated with biogenic substrates in Cenozoic deep-water sediments of Washington State

Cenozoic deep−water sediments of the Lincoln Creek, Makah, and Pysht formations in western Washington State, USA, contain sunken driftwood and whale bones that were colonized by invertebrates which largely depend on this type of transient habitat. These fossil woodand whale−fall faunules yielded six new mollusk species that appear to have been endemic to these biogenic microhabitats, except for one species which also occurs in cold−seep limestones. The new gastropod species are the neomphalid Leptogyra squiresi, the buccinid Colus sekiuensis, the allogastropod Xylodiscula okutanii, and the new bivalve species are the protobranch “Nuculana” posterolaevia, the mytilid Idas? olympicus, and the heterodont Thyasira xylodia