Towards a Molecular Inventory of Protostellar Discs

The chemical environment in circumstellar discs is a unique diagnostic of the thermal, physical and chemical environment. In this paper we examine the structure of star formation regions giving rise to low mass stars, and the chemical environment inside them, and the circumstellar discs around the developing stars.Comment: 9 page PDF, 550 kbyte

Synthesis and structural studies of a lanthanide complex of a calix[4]arene tris-amide

The coordination chemistry of amide-substituted calixarenes is reviewed. The synthesis of a gadolinium complex of a trisamide calix[4]arene is described, involving the reaction of 5,11,17,23-tetra-tert-butyl-24-hydroxy-26,27,28-tris(diethylcarbamoylmethoxy) calix[4]arene (L) with gadolinium picrate dodecahydrate. Structural studies demonstrated that the complex can be formulated as [(pic-O)Gd{(L H)(EtOH)}](pic)2 EtOH

Cooling Radiation and the Lyman-alpha Luminosity of Forming Galaxies

We examine the cooling radiation from forming galaxies in hydrodynamic simulations of the LCDM model (cold dark matter with a cosmological constant), focusing on the Ly-alpha line luminosities of high-redshift systems. Primordial composition gas condenses within dark matter potential wells, forming objects with masses and sizes comparable to the luminous regions of observed galaxies. As expected, the energy radiated in this process is comparable to the gravitational binding energy of the baryons, and the total cooling luminosity of the galaxy population peaks at z ~= 2. However, in contrast to the classical picture of gas cooling from the \sim 10^6 K virial temperature of a typical dark matter halo, we find that most of the cooling radiation is emitted by gas with T < 20,000 K. As a consequence, roughly 50% of this cooling radiation emerges in the Ly-alpha line. While a galaxy's cooling luminosity is usually smaller than the ionizing continuum luminosity of its young stars, the two are comparable in the most massive systems, and the cooling radiation is produced at larger radii, where the Ly-alpha photons are less likely to be extinguished by dust. We suggest, in particular, that cooling radiation could explain the two large (\sim 100 kpc), luminous (L_{Ly-alpha} \sim 10^{44} erg s^{-1}) ``blobs'' of Ly-alpha emission found in Steidel et al.'s (1999) narrow band survey of a z = 3 proto-cluster. Our simulations predict objects of the observed luminosity at about the right space density, and radiative transfer effects can account for the observed sizes and line widths. We discuss observable tests of this hypothesis for the nature of the Ly-alpha blobs, and we present predictions for the contribution of cooling radiation to the Ly-alpha luminosity function of galaxies as a function of redshift.Comment: Submitted to ApJ. 28 pages including 9 PS figures. Version with color figures available at http://donald.astro.umass.edu/~fardal/papers/cooling/cooling.htm

A Sea-Level Lowstand (Devil\u27s Point Event) Recorded in Bahamian Reefs: Comparison with Other Last Interglacial Climate Proxies

Reprinted from: Benjamin J. Greenstein and Cindy K. Carney (eds.) Proceedings of the 10th Symposium on the Geology of the Bahamas and Other Carbonate Regions: San Salvador, Gerace Research Cente

Guide to Bahamian Ichnology: Pleistocene, Holocene, and Modern Environments: A Field Trip Guide

This guide was prepared for the Fourth International Ichnofabric Workshop (IIW- 4) to be hosted by the Bahamian Field Station and held on San Salvador Island on March 15-22, 1997. About 35 scientists representing 15 countries are registered to attend the workshop. The focus of discussion in the infonnal scientific sessions will be the uses of ichnofabric analysis in sedimentary geology. An ichnofabric is the texture or internal structure created within a sedimentary substrate from the bioturbating activity of organisms. Ichnofabric analysis is a new and emerging area of ichnology (the study of trace fossils), and its methods are proving useful in enhancing sedimentary facies recognition and interpretations, event correlation, paleoenvironmental and paleoecological reconstructions, reservoir prediction, and more. Ichnologists are field oriented, and San Salvador Island, with its diverse and largely pristine modem tropical, carbonate environments and well exposed Pleistocene and Holocene rock record, provides provides a fantastic natural laboratory for the study of all aspects of carbonate geology. San Salvador also is a geologically and ichnologically well known island, so proven field localities are readily available. This doesn\u27t mean that new ichnologic discoveries and interpretations won\u27t be forthcoming - they certainly will be, and probably some will occur during the time of the IIW-4 workshop. My colleague Brian White and I have been working in the Bahamas for just over 15 years. We know a great deal about Bahamian geology, but with every field excursion we find something new, and I often think that we have just scratched the surface! The centerpiece of this guide is the descriptions of six Ichno-localities on San Salvador Island that provide outstanding examples of modem traces or trace fossils and illustrate a veriety of ichnologic principles. In addition, in composite form, the stops provide a good overview of the Pleistocene, Holocene, and modem geology and environments of San Salvador. All of the stops are readily accessible from the main roads on the island. The initial chapter provides a brief introduction to the geology of the Bahamas and San Salvador for first-time visitors. The three chapters at the end of the guide are thematic and designed to expand the ichnologic perspectives to include borer organisms, plant trace fossils, and ichnologic sites in the Bahamas beyond San Salvador. I hope this guide will be useful to a broad spectrum of visitors to the Bahamian Field Station for several years to come, as well as to ichnologists unable to attend this workshop but with an interest in carbonates. See other Smith authored Field Trip Guides of Gerace Research Centre

Bahamian Sangamonian Coral Reefs and Sea-Level Change

Reprinted from James L. Carew (ed.) May 30–June 3, 1996, Proceedings of the 8th Symposium on the Geology of the Bahamas and Other Carbonate Regions: Bahamian Field Station, San Salvador, Bahamas

Alfred Werner revisited: Some subtleties of complex ion synthesis and isomerism

The synthesis of perhaps the best-known Wernerian complex, [Co(en)3]3+, is very efficient, but nonetheless results in the formation of various side-products. Today, the use of X-ray crystallography to characterise such materials provides new insights into the reaction pathways of the synthesis and the exact forms possible for the products. The structures of cis-[Co(en)2(H2NCH2CH2NH3)Cl]Cl[ZnCl4], cis-[Co(en)2(NH3)Cl]S2O6, [Co(en)(NH2CH2CH2N=CHCH2NH2))Cl][ZnCl4], [Co(en)2(N-CH3en)][Co(CN)6]?2 H2O and [Co(en)2(N-CH3en)][Co(CN)6], are presently discussed in this regard