Constraints on the Dark Side of the Universe and Observational Hubble Parameter Data

This paper is a review on the observational Hubble parameter data that have gained increasing attention in recent years for their illuminating power on the dark side of the universe --- the dark matter, dark energy, and the dark age. Currently, there are two major methods of independent observational H(z) measurement, which we summarize as the "differential age method" and the "radial BAO size method". Starting with fundamental cosmological notions such as the spacetime coordinates in an expanding universe, we present the basic principles behind the two methods. We further review the two methods in greater detail, including the source of errors. We show how the observational H(z) data presents itself as a useful tool in the study of cosmological models and parameter constraint, and we also discuss several issues associated with their applications. Finally, we point the reader to a future prospect of upcoming observation programs that will lead to some major improvements in the quality of observational H(z) data.Comment: 20 pages, 6 figures, and 1 table, uses REVTeX 4.1. Review article, accepted by Advances in Astronom

5,5′-(Butane-1,4-di­yl)bis­(1H-tetra­zole) dihydrate

The title compound, C6H10N8·2H2O, was prepared by the reaction of hexanedinitrile and sodium azide. The di-1H-tetra­zole mol­ecule lies on a crystallographic centre of inversion and is linked to the water mol­ecules by N—H⋯O and O—H⋯N hydrogen bonds, forming a two-dimensional supra­molecular structure in the crystal

{Bis[4-(2-pyrid­yl)pyrimidin-2-yl] sulfide}dibromidocobalt(II)

The title compound, [CoBr2(C18H12N6S)], is a mononuclear complex in which a twofold rotation axis passes through the Co and S atoms. The CoII center is six-coordinated by four N atoms from one bis­[4-(2-pyrid­yl)pyrimidin-2-yl] sulfide (L) ligand and two bromide anions, forming an octa­hedral coordination geometry, where the four donor N atoms are located in the equatorial plane and the Br atoms occupy the axial positions. The sum of the bond angles around the Co atom in the equatorial plane is 360.5°, with the four N atoms and the central Co atom almost coplanar. In the crystal structure, the mononuclear units are linked by π–π stacking inter­actions (the inter­planar distances are 3.469 and 3.533 Å, and the corresponding centroid–centroid distances are 3.791 and 3.896 Å) into a three-dimensional supra­molecular network

Three essays on the trade effect of US farm subsidies

The thesis comprises three essays investigating the effect of US farm subsidies on its international trade. The results, after accounted for potential endogeneity, indicate that US farm subsidies have significant on US exports, and imports at both aggregate and disaggregate level. The finding would have important implications for policy makers and trade negotiators in the context that reform in agricultural sector is the central debate in Doha Rounds among WTO members