FACTORS INFLUENCING RATES OF ADOPTION OF TRICHOMONIASIS VACCINE BY NEVADA RANGE CATTLE PRODUCERS

Tritrichimonas foetus vaccine has been marketed since 1989 to combat the trichomoniasis disease that causes reproductive failure and considerable economic loss to Nevada ranchers. An ex post technology adoption model is estimated to examine the possible adoption rate, to identify the factors that may influence the adoption behavior, and to test how the probability of adoption for five possible adopter groups would change due to changes in various ranch specific factors. Results indicate that use of computers, veterinary checkup of herd, and herd size influence the probability of adoption. Model results show that cooperative extension programs enhance the rate of adoption.Livestock Production/Industries,

On the Formation of Galaxy Halos: Comparing NGC 5128 and the Local Group Members

The metallicity distribution function (MDF) for the old red-giant stars in the halo of NGC 5128, the nearest giant elliptical galaxy, is virtually identical with the MDF for the old-disk stars in the LMC and also strongly resembles the halo MDF in M31. These galaxies all have high mean halo metallicities ( ~ -0.4$) with very small proportions of low-metallicity stars. These observations reinforce the view that metal-rich halos are quite normal for large galaxies of all types. Such systems are unlikely to have built up by accretion of pre-existing, gas-free small satellite galaxies, unless these satellites had an extremely shallow mass distribution (d log N / d log M > -1). We suggest that the halo of NGC 5128 is more likely to have assembled from hierarchical merging of gas-rich lumps in which the bulk of star formation took place during or after the merger stage.Comment: 10 pages, LaTeX, plus 3 figures in separate postscript files; Astronomical Journal, in press for December 200

Comparison of the interactions in the rare gas hydride and Group 2 metal hydride anions

We study both the rare gas hydride anions, RG–H− (RG = He–Rn) and Group 2 (Group IIa) metal hydride anions, MIIaH− (MIIa = Be–Ra), calculating potential energy curves at the CCSD(T) level with augmented quadruple and quintuple basis sets, and extrapolating the results to the basis set limit. We report spectroscopic parameters obtained from these curves; additionally, we study the Be–He complex. While the RG–H− and Be–He species are weakly bound, we show that, as with the previously studied BeH− and MgH− species, the other MIIaH− species are strongly bound, despite the interactions nominally also being between two closed shell species: M(ns2) and −(1s2). We gain insight into the interactions using contour plots of the electron density changes and population analyses. For both series, the calculated dissociation energy is significantly less than the ion/induced-dipole attraction term, confirming that electron repulsion is important in these species; this effect is more dramatic for the MIIaH− species than for RG–H−. Our analyses lead us to conclude that the stronger interaction in the case of the MIIaH− species arises from sp and spd hybridization, which allows electron density on the MIIa atom to move away from the incoming H−

Strategic Relationships in a Small Business Context: The Impact of Information Quality and Continuous Quality Improvement

This study examines the performance between operational variables for small and medium-sized businesses (SMEs) within the context of interorganizational relationships. Specifically, it investigates the role of information quality and continuous quality improvement and the varying importance that SMEs place on each of these constructs. The sample consists of 134 vendors of a large university in the southwestern region of the United States.The results indicate that there is a positive relationship between information quality and continuous quality improvement with performance in SMEs. Implications for both research and practice, as well as ideas for future research, are discussed

The Impact of Strategic Focus and Previous Business Experience on Small Business Performance

This study examines whether or not having an internal or external strategic focus interacts with prior experience in small business to impact perceived organizational performance. Utilizing a sample of 237 small business owners from the southeast U.S., a factorial ANOVA and Regression Analysis were used to test hypotheses related to these constructs. Results indicated that utilizing an internal focus was associated with higher performance among both experienced and inexperienced small business owners; however, an external focus was only positively related to performance for inexperienced business owners. No overall difference in performance was found for experience itself

Month-Timescale Optical Variability in the M87 Jet

A previously inconspicuous knot in the M87 jet has undergone a dramatic outburst and now exceeds the nucleus in optical and X-ray luminosity. Monitoring of M87 with the Hubble Space Telescope and Chandra X-ray Observatory during 2002-2003, has found month-timescale optical variability in both the nucleus and HST-1, a knot in the jet 0.82'' from the nucleus. We discuss the behavior of the variability timescales as well as spectral energy distribution of both components. In the nucleus, we see nearly energy-independent variability behavior. Knot HST-1, however, displays weak energy dependence in both X-ray and optical bands, but with nearly comparable rise/decay timescales at 220 nm and 0.5 keV. The flaring region of HST-1 appears stationary over eight months of monitoring. We consider various emission models to explain the variability of both components. The flares we see are similar to those seen in blazars, albeit on longer timescales, and so could, if viewed at smaller angles, explain the extreme variability properties of those objects.Comment: 4 pages, 3 figures, ApJ Lett., in pres

Globular Cluster Systems in Brightest Cluster Galaxies: Bimodal Metallicity Distributions and the Nature of the High-Luminosity Clusters

We present new (B,I) photometry for the globular cluster systems in eight Brightest Cluster Galaxies (BCGs), obtained with the ACS/WFC camera on the Hubble Space Telescope. In the very rich cluster systems that reside within these giant galaxies, we find that all have strongly bimodal color distributions All the BCGs show population gradients, with much higher relative numbers of red clusters within 5 kpc of their centers, consistent with their having formed at later times than the blue, metal-poor population. A striking new feature of the color distributions emerging from our data is that for the brightest clusters (M_I < -10.5) the color distribution becomes broad and less obviously bimodal. we suggest that it may be a characteristic of many BCGs. Furthermore, the blue (metal-poor) clusters become progressively redder with increasing luminosity, following a mass/metallicity scaling relation Z ~ M^0.55. We argue that these GCS characteristics are consistent with a hierarchical-merging formation picture in which the metal-poor clusters formed in protogalactic clouds or dense starburst complexes with gas masses in the range 10^7 - 10^10 M_Sun, but where the more massive clusters on average formed in bigger clouds with deeper potential wells where more pre-enrichment could occur.Comment: 48 pages, 24 Figures, PDF, Submitted to Astrophys.J. and refereed. For complete pdf file with better figures, see: http://physwww.mcmaster.ca/%7Eharris/Preprints.htm

Photometry and the Metallicity Distribution of the Outer Halo of M31

We have conducted a wide-field CCD-mosaic study of the resolved red-giant branch (RGB) stars of M31, in a field located 20 kpc from the nucleus along the SE minor axis. In our (I, V-I) color-magnitude diagram, RGB stars in the top three magnitudes of the M31 halo are strongly present. Photometry of a more distant control field to subtract field contamination is used to derive the `cleaned' luminosity function and metallicity distribution function (MDF) of the M31 halo field. From the color distribution of the foreground Milky Way halo stars, we find a reddening E(V-I)= 0.10 +/- 0.02 for this field, and from the luminosity of the RGB tip, we determine a distance modulus (m-M)_o = 24.47 +/- 0.12 (= 783 +/- 43 kpc). The MDF is derived from interpolation within an extensive new grid of RGB models (Vandenberg et al. 2000). The MDF is dominated by a moderately high-metallicity population ([m/H]~ -0.5) found previously in more interior M31 halo/bulge fields, and is much more metal-rich than the [m/H]~ -1.5 level in the Milky Way halo. A significant (~30% - 40%, depending on AGB star contribution) metal-poor population is also present. To first order, the shape of the MDF resembles that predicted by a simple, single-component model of chemical evolution starting from primordial gas with an effective yield y=0.0055. It strongly resembles the MDF recently found for the outer halo of the giant elliptical NGC 5128 (Harris et al. 2000), though NGC 5128 has an even lower fraction of low-metallicity stars. Intriguingly, in both NGC 5128 and M31, the metallicity distribution of the globular clusters in M31 does not match the halo stars; the clusters are far more heavily weighted to metal-poor objects. We suggest similarities in the formation and early evolution of massive, spheroidal stellar systems.Comment: to appear in the Astronomical Journal; 43 pages, including 15 figure

The Kinematics and Dynamics of the Globular Clusters and the Planetary Nebulae of NGC 5128

A new kinematic and dynamic study of the halo of the giant elliptical galaxy, NGC 5128, is presented. From a spectroscopically confirmed sample of 340 globular clusters and 780 planetary nebulae, the rotation amplitude, rotation axis, velocity dispersion, and the total dynamical mass are determined for the halo of NGC 5128. The globular cluster kinematics were searched for both radial dependence and metallicity dependence by subdividing the globular cluster sample into 158 metal-rich ([Fe/H] > -1.0) and 178 metal-poor ([Fe/H] < -1.0) globular clusters. Our results show the kinematics of the metal-rich and metal-poor subpopulations are quite similar. The kinematics are compared to the planetary nebula population where differences are apparent in the outer regions of the halo. The total mass of NGC 5128 is found using the Tracer Mass estimator (Evans et al. 2003), to determine the mass supported by internal random motions, and the spherical component of the Jeans equation to determine the mass supported by rotation. We find a total mass of (1.0+/-0.2) x 10^(12) Msun from the planetary nebulae data out to a projected radius of 90 kpc and (1.3+/-0.5) x 10^(12) Msun from the globular clusters out to a projected radius of 50 kpc. Lastly, we present a new and homogeneous catalog of known globular clusters in NGC 5128. This catalog combines all previous definitive cluster identifications from radial velocity studies and HST imaging studies, as well as 80 new globular clusters from a study of M.A. Beasley et al. (2007, in preparation).Comment: Accepted in the Astronomical Journal,52 pages, 13 figures, 6 tables - Changes made to Table 1 from originally submitted 0704.118