Optical Morphology Evolution of Infrared Luminous Galaxies in GOODS-N

We combine optical morphologies and photometry from HST, redshifts from Keck, and mid-infrared luminosities from Spitzer for an optically selected sample of~800 galaxies in GOODS-N to track morphology evolution of infrared luminous galaxies (LIRGs) since redshift z=1. We find a 50% decline in the number of LIRGs from z~1 to lower redshift, in agreement with previous studies. In addition, there is evidence for a morphological evolution of the populations of LIRGs. Above z=0.5, roughly half of all LIRGs are spiral, the peculiar/irregular to spiral ratio is ~0.7, and both classes span a similar range of L_{IR} and M_B. At low-z, spirals account for one-third of LIRGs, the peculiar to spiral fraction rises to 1.3, and for a given M_B spirals tend to have lower IR luminosity than peculiars. Only a few percent of LIRGs at any redshift are red early-type galaxies. For blue galaxies (U-B < 0.2), M_B is well correlated with log(L_{IR}) with an RMS scatter (about a bivariate linear fit) of ~0.25 dex in IR luminosity. Among blue galaxies that are brighter than M_B = -21, 75% are LIRGs, regardless of redshift. These results can be explained by a scenario in which at high-z, most large spirals experience an elevated star formation rate as LIRGs. Gas consumption results in a decline of LIRGs, especially in spirals, to lower redshifts.Comment: 6 pages, 2 figures, accepted ApJ

OPERATIONAL EFFICIENCY OF A U.S./CANADIAN WHEAT POOL: A GAME THEORY ANALYSIS

The problem of declining wheat prices and excess supply has been the subject of recent economic studies partly because it coincides with the Federal Agriculture Improvement and Reform (FAIR) Act of 1996, and partly because efforts to decrease supply domestically have led to increased imports from Canada. This paper develops a game theory optimization model of market efficiency and derives conditions under which voluntary pooling is sustained for U.S./Canadian durum and hard red spring wheat producers. Analysis reveals that U.S. and Canadian farmers can increase farm returns with efficiency gains from pooling and by internalizing benefits from grain blending and logistics. The model is used to analyze diverse factors affecting the sustainability of such a pool.Voluntary pooling, game theory, efficiency gains, durum and HRS wheat marketing, Crop Production/Industries, Marketing,

Spatially Resolved Stellar Populations of Eight GOODS-South Active Galactic Nuclei at z ~ 1

We present a pilot study of the stellar populations of eight active galactic nucleus (AGN) hosts at z ~ 1 and compare with (1) lower redshift samples and (2) a sample of nonactive galaxies of similar redshift. We utilize K' images in the Great Observatories Origins Deep Survey South field obtained with the laser guide star adaptive optics system at Keck Observatory. We combine these K' data with B, V, i, and z imaging from the Advanced Camera for Surveys on Hubble Space Telescope to give multicolor photometry at a matched spatial resolution better than 100 mas in all bands. The hosts harbor AGNs as inferred from their high X-ray luminosities (LX > 10^42 erg s^–1) or mid-IR colors. We find a correlation between the presence of younger stellar populations and the strength of the AGN, as measured with [O III] line luminosity or X-ray (2-10 keV) luminosity. This finding is consistent with similar studies at lower redshift. Of the three Type II galaxies, two are disk galaxies and one is of irregular type, while in the Type I sample there are only one disk-like source and four sources with smooth, elliptical/spheroidal morphologies. In addition, the mid-IR spectral energy distributions of the strong Type II AGNs indicate that they are excited to Luminous InfraRed Galaxy (LIRG) status via galactic starbursting, while the strong Type I AGNs are excited to LIRG status via hot dust surrounding the central AGN. This supports the notion that the obscured nature of Type II AGNs at z ~ 1 is connected with global starbursting and that they may be extincted by kpc-scale dusty features that are by-products of this starbursting

OPERATIONAL EFFICIENCY OF US/CANADA WHEAT POOL: A GAME THEORY ANALYSIS

This paper develops a game theory optimization model of market efficiency and derives conditions under which voluntary pooling is sustained for US/Canada durum and hard red spring wheat producers. Analysis reveals that United States and Canadian farmers can increase farm returns with efficiency gains from pooling and by internalizing benefits from grain blending and logistics. The model is used to analyze diverse factors affecting the sustainability of such a pool.Crop Production/Industries, Marketing,

ECONOMIC ANALYSIS OF THE PROPOSED NORTH DAKOTA WHEAT POOL

The ND Durum Wheat Pool may provide additional revenue to durum wheat producers by raising the domestic prices in the North American market with full cooperation from the Canadian Wheat Board. The pool also could provide additional revenue to its members by improving marketing efficiency. On the other hand, the ND Spring Wheat Pool is less likely to provide additional revenue to spring wheat producers by raising domestic prices, mainly because hard red spring and winter wheat are highly substitutable. Efficiency gains also could be smaller than for durum wheat.marketing pool, market power, efficiency gains, durum wheat, hard red spring wheat, pool price, organizational structure, operating costs, Marketing,

ECONOMIC ANALYSIS OF THE PROPOSED NORTH DAKOTA WHEAT POOL; SUMMARY

The ND Durum Wheat Pool may provide additional revenue to durum wheat producers by raising the domestic prices in the North American market with full cooperation from the Canadian Wheat Board. The pool also could provide additional revenue to its members by improving marketing efficiency. On the other hand, the ND Spring Wheat Pool is less likely to provide additional revenue to spring wheat producers by raising domestic prices, mainly because hard red spring and winter wheat are highly substitutable. Efficiency gains also could be smaller than for durum wheat.marketing pool, market power, efficiency gains, durum wheat, hard red spring wheat, pool price, organizational structure, operating costs, Marketing,