Testing the Least Action Principle in an Omega_0=1 Universe

The least action principle (LAP) is a dynamically rigorous method for deriving the history of galaxy orbits. In particular it is an Omega_0 test, predicting current epoch galaxy velocities as a function of position and of the cosmological background. It is most usefully applied to in--falling structures, such as the local group, where its application indicates that the preferred cosmological model is Omega_0 = 0.1 and h=0.75 (h is the Hubble parameter in units of 100 Km s^-1 Mpc^-1). The method assumes that all the mass acts as if it were distributed as the visible galaxies. We test the reliability of the LAP to Local Group-like systems extracted from Omega_0=1 N--body simulations. While the orbits of the galaxies are qualitatively well reconstructed, the LAP systematically underestimates the mass of the system. This failure is attributed to the presence of extended halos weakly clustered around visible galaxies which prevent a large fraction of the group mass from being detected by the LAP technique. We conclude that the LAP method cannot rule out an Omega_0=1 value on the Local Group scale. Better constraints on Omega_0 may be obtained by applying this technique to in--falling systems, such as clusters, containing objects with separations large compared to galaxy sizes.Comment: accepted by APJ, uuencoded-compressed-tarred PostScript file including figures. SISSA Ref. 56/94/

A PARTIAL-ADJUSTMENT, MIXED LINEAR MODEL OF PRICE DISCOVERY IN AN EXPERIMENTAL MARKET FOR FED CATTLE

The Fed Cattle Market Simulator (FCMS) was developed by a team of researchers at Oklahoma State University to aid in understanding the forces that influence price discovery in the fed cattle market. Participants in the FCMS play the role of feedlot marketing managers and packing plant procurement agents, and trade paper pens of cattle in the experimental market. Previous research with the FCMS has not attempted to capture the dynamic nature of the price discovery process; this paper uses a partial-adjustment approach to accomplish that goal. A mixed linear model is used to accommodate both fixed and random effects in the data. Results show that the transaction price adjusts only sixteen percent on a week-by-week basis to its desired level. As such, the price discovery process in the experimental market is said to be characterized by slow adjustment, due in part to biological lags in the beef supply chain. This result will be useful in enhancing understanding of the real fed cattle market.Livestock Production/Industries,

Comparing Canadian and U.S. Cattle Feeding Pricing Practices and Perceptions of Pricing Issues

Competition among beef packing firms, use of so-called captive supply, and methods of price discovery have been prolonged, contentious issues in the U.S. beef industry for two decades or more. While of lesser apparent concern in Canada for many years, these same matters rose to the forefront of beef industry issues after the Canada–U.S. border closure that resulted from Canada’s first case of bovine spongiform encephalopathy (BSE) in May 2003.Marketing,

Success Factors for New Generation Cooperatives

The goal of this research was to determine success factors for New Generation Cooperatives (NGCs). A self-explicated approach was used to assess the importance of various factors grouped in broad categories using data collected from a mailout survey of NGC managers. Results suggest that factors in the "Planning and Development" and "Financing and Costs" categories are considered to be critically important by NGC managers, though differences in factor rankings exist between managers of enterprises involved in the processing of different commodities.New Generation Cooperative, self-explication, Agribusiness,

SUCCESS FACTORS FOR VALUE ADDED NEW GENERATION COOPERATIVES

Two surveys of New Generation Cooperative (NGC) managers were carried out to ascertain the factors most important to their success. Factors in the Planning and Development as well as the Financing and Cost categories were most important, and NGCs with more employees and more members' equity are most successful.Agribusiness,

First Assessment of Mountains on Northwestern Ellesmere Island, Nunavut, as Potential Astronomical Observing Sites

Ellesmere Island, at the most northerly tip of Canada, possesses the highest mountain peaks within 10 degrees of the pole. The highest is 2616 m, with many summits over 1000 m, high enough to place them above a stable low-elevation thermal inversion that persists through winter darkness. Our group has studied four mountains along the northwestern coast which have the additional benefit of smooth onshore airflow from the ice-locked Arctic Ocean. We deployed small robotic site testing stations at three sites, the highest of which is over 1600 m and within 8 degrees of the pole. Basic weather and sky clarity data for over three years beginning in 2006 are presented here, and compared with available nearby sea-level data and one manned mid-elevation site. Our results point to coastal mountain sites experiencing good weather: low median wind speed, high clear-sky fraction and the expectation of excellent seeing. Some practical aspects of access to these remote locations and operation and maintenance of equipment there are also discussed.Comment: 21 pages, 2 tables, 15 figures; accepted for publication in PAS

Catalog of Galaxy Morphology in Four Rich Clusters: Luminosity Evolution of Disk Galaxies at 0.33<z<0.83

Hubble Space Telescope (HST) imaging of four rich, X-ray luminous, galaxy clusters (0.33<z<0.83) is used to produce quantitative morphological measurements for galaxies in their fields. Catalogs of these measurements are presented for 1642 galaxies brighter than F814W(AB)=23.0 . Galaxy luminosity profiles are fitted with three models: exponential disk, de Vaucouleurs bulge, and a disk-plus-bulge hybrid model. The best fit is selected and produces a quantitative assessment of the morphology of each galaxy: the principal parameters derived being B/T, the ratio of bulge to total luminosity, the scale lengths and half-light radii, axial ratios, position angles and surface brightnesses of each component. Cluster membership is determined using a statistical correction for field galaxy contamination, and a mass normalization factor (mass within boundaries of the observed fields) is derived for each cluster. In the present paper, this catalog of measurements is used to investigate the luminosity evolution of disk galaxies in the rich-cluster environment. Examination of the relations between disk scale-length and central surface brightness suggests, under the assumption that these clusters represent a family who share a common evolutionary history and are simply observed at different ages, that there is a dramatic change in the properties of the small disks (h < 2 kpc). This change is best characterized as a change in surface brightness by about 1.5 magnitude between z=0.3 and z=0.8 with brighter disks at higher redshifts.Comment: 53 pages, including 13 figures and 7 tables. Accepted for publication in the Astrophysical Journal Supplement Serie

The Luminosity Function of Field Galaxies in the CNOC1 Redshift Survey

We have computed the luminosity function for 389 field galaxies from the Canadian Network for Observational Cosmology cluster redshift survey (CNOC1), over redshifts z = 0.2-0.6. We find Schechter parameters M^* - 5 log h = -19.6 \pm 0.3 and \alpha = -0.9 \pm 0.2 in rest-frame B_{AB}. We have also split our sample at the color of a redshifted but nonevolving Sbc galaxy, and find distinctly different luminosity functions for red and blue galaxies. Red galaxies have a shallow slope \alpha \approx -0.4 and dominate the bright end of the luminosity function, while blue galaxies have a steep \alpha \approx -1.4 and prevail at the faint end. Comparisons of the CNOC1 results to those from the Canada-France (CFRS) and Autofib redshift surveys show broad agreement among these independent samples, but there are also significant differences which will require larger samples to resolve. Also, in CNOC1 the red galaxy luminosity density stays about the same over the range z = 0.2-0.6, while the blue galaxy luminosity density increases steadily with redshift. These results are consistent with the trend of the luminosity density vs. redshift relations seen in the CFRS, though the normalizations of the luminosity densities appear to differ for blue galaxies. Comparison to the local luminosity function from the Las Campanas redshift survey (LCRS) shows that the luminosity density at z \approx 0.1 is only about half that seen at z \approx 0.4. A change in the luminosity function shape, particularly at the faint end, appears to be required to match the CNOC1 and LCRS luminosity functions, if galaxy evolution is the sole cause of the differences seen. However, it should be noted that the specific details of the construction of different surveys may complicate the comparison of results and so may need to be considered carefully.Comment: 22 pages, including 6 postscript figures, uses AASTEX v4.0 style files. Corrected minor typos and updated references. Results and conclusions unchanged. Final version to appear in the Astrophysical Journa