SOME EMPIRICAL METHODS OF ESTIMATING ADVERTISING EFFECTS IN DEMAND SYSTEMS: AN APPLICATION TO DRIED FRUITS

Two different methods of incorporating advertising effects into Almost Ideal Demand Systems (AIDS) are presented. Both advertising schemes are designed to allow theoretical restrictions to hold globally rather than at particular sample points. The models are estimated for California figs, prunes, and raisins. Empirical results indicate that generic advertising effects for these three dried fruits are generally weak when compared to price and total expenditure effects. Estimated cross-commodity effects also are relatively small except for the negative effect of raisin advertising on the quantity of prunes demanded.Demand and Price Analysis, Marketing,

Compact Nuclei in Galaxies at Moderate Redshift: I. Imaging and Spectroscopy

This study explores the space density and properties of active galaxies to z=0.8. We have investigated the frequency and nature of unresolved nuclei in galaxies at moderate redshift as indicators of nuclear activity such as Active Galactic Nuclei (AGN) or starbursts. Candidates are selected by fitting imaged galaxies with multi-component models using maximum likelihood estimate techniques to determine the best model fit. We select those galaxies requiring an unresolved, point source component in the galaxy nucleus, in addition to a disk and/or bulge component, to adequately model the galaxy light. We have searched 70 WFPC2 images primarily from the Medium Deep Survey for galaxies containing compact nuclei. In our survey of 1033 galaxies, the fraction containing an unresolved nuclear component greater than 3% of the total galaxy light is 16+/-3% corrected for incompleteness and 9+/-1% for nuclei greater than 5% of the galaxy light. Spectroscopic redshifts have been obtained for 35 of our AGN/starburst candidates and photometric redshifts are estimated to an accuracy of sigma_z=0.1 for the remaining sample. In this paper, the first of two in this series, we present the selected HST imaged galaxies having unresolved nuclei and discuss the selection procedure. We also present the ground-based spectroscopy for these galaxies as well as the photometric redshifts estimated for those galaxies without spectra.Comment: 56 pages, 22 figures, to appear in ApJ Supplement Series, April 199

Compact Nuclei in Moderately Redshifted Galaxies

The Hubble Space Telescope WFPC2 is being used to obtain high-resolution images in the V and I bands for several thousand distant galaxies as part of the Medium Deep Survey (MDS). An important scientific aim of the MDS is to identify possible AGN candidates from these images in order to measure the faint end of the AGN luminosity function as well as to study the host galaxies of AGNs and nuclear starburst systems. We are able to identify candidate objects based on morphology. Candidates are selected by fitting bulge+disk models and bulge+disk+point source nuclei models to HST imaged galaxies and determining the best model fit to the galaxy light profile. We present results from a sample of MDS galaxies with I less than 21.5 mag that have been searched for AGN/starburst nuclei in this manner. We identify 84 candidates with unresolved nuclei in a sample of 825 galaxies. For the expected range of galaxy redshifts, all normal bulges are resolved. Most of the candidates are found in galaxies displaying exponential disks with some containing an additional bulge component. 5% of the hosts are dominated by an r^-1/4 bulge. The V-I color distribution of the nuclei is consistent with a dominant population of Seyfert-type nuclei combined with an additional population of starbursts. Our results suggest that 10% +/- 1% of field galaxies at z less than 0.6 may contain AGN/starburst nuclei that are 1 to 5 magnitudes fainter than the host galaxies.Comment: 12 pages AASTeX manuscript, 3 separate Postscript figures, to be published in ApJ Letter

Mathematical model of hydropad seals

Issued as Final report, Project no. E-25-695Final report has co-author: Itzhak Gree

A Deep Multicolor Survey I. Imaging Observations and Catalog of Stellar Objects

We have used the KPNO 4-meter Mayall telescope to image 0.83 square degrees of sky in six fields at high galactic latitude in six filters spanning 3000-10000\AA\ to magnitude limits ranging from 22.1 to 23.8. We have assembled a catalog of 21,375 stellar objects detected in the fields for use primarily in conducting a multicolor search for quasars. This paper describes the data reduction techniques used on the CCD data, the methods used to construct the stellar object catalog, and the simulations performed to understand its completeness and contamination.Comment: To Appear in ApJ Supplement, 1996. 168k uuencoded gunzipped tarred tex file (requires aas2pp4.sty and tighten.sty) and 4 PostScript figures. Also available at http://astro.as.arizona.edu/~pathall/astro.html#preprint

X-ray Emission from the Host Clusters of Powerful AGN

(Abridged) We report the detection of X-ray emission from the host cluster of the radio-quiet quasar H1821+643 with the ROSAT HRI, and the non-detection of the host cluster of the radio-loud quasar 3C206 using the EINSTEIN HRI. CL1821+643 has a rest-frame 0.1-2.4 keV luminosity of 3.74$\pm$0.57 h$_{50}^{-2}$ 10^45 ergs/sec, 38% from a barely resolved cooling flow component, which places it among the most X-ray luminous clusters known. The cluster emission complicates interpretation of previous X-ray spectra of this field; in particular, the observed FeK$\alpha$ emission can probably be attributed entirely to the cluster, and either the quasar is relatively X-ray quiet for its optical luminosity or the cluster has a relatively low temperature for its luminosity. We combine these data with the recent detection of X-ray emission from the host cluster of the `buried' radio-quiet quasar IRAS 09104+4109, our previous upper limits for the host clusters of two z$\sim$0.7 RLQs, and literature data on FR II radio galaxies and compare to the predictions of three models for the presence and evolution of powerful AGN in clusters: the low-velocity-dispersion model, the low-ICM-density model, and the cooling flow model. Neither of the latter two models can explain all the observations. We suggest that strong interactions with gas-containing galaxies may be the only mechanism needed to explain the presence and evolution of powerful AGN in clusters, consistent with the far-IR and optical properties of the host galaxies studied here. However, the cooling flow model cannot be ruled out for at least some objects, and it is likely that both processes are at work. Each scenario makes predictions for future X-ray and optical observations which can test their relative importance.Comment: Scheduled for the April 1997 Astronomical Journal; 35 pages including 5 figures; also available from http://ethel.as.arizona.edu/~pathall/astro.htm

U(2) Flavor Physics without U(2) Symmetry

We present a model of fermion masses based on a minimal, non-Abelian discrete symmetry that reproduces the Yukawa matrices usually associated with U(2) theories of flavor. Mass and mixing angle relations that follow from the simple form of the quark and charged lepton Yukawa textures are therefore common to both theories. We show that the differing representation structure of our horizontal symmetry allows for new solutions to the solar and atmospheric neutrino problems that do not involve modification of the original charged fermion Yukawa textures, or the introduction of sterile neutrinos.Comment: 12 pages RevTeX, 1 eps figure. A few typos correcte

Hot Subdwarf Stars Among the Objects Rejected from the PG Catalog: a First Assessment Using GALEX Photometry

The hot subdwarf (sd) stars in the Palomar Green (PG) catalog of ultraviolet excess (UVX) objects play a key role in investigations of the frequency and types of binary companions and the distribution of orbital periods. These are important for establishing whether and by which channels the sd stars arise from interactions in close binary systems. It has been suggested that the list of PG sd stars is biased by the exclusion of many stars in binaries, whose spectra show the Ca II K line in absorption. A total of 1125 objects that were photometrically selected as candidates were ultimately rejected from the final PG catalog using this K-line criterion. We study 88 of these "PG-Rejects" (PGRs), to assess whether there are significant numbers of unrecognized sd stars in binaries among the PGR objects. The presence of a sd should cause a large UVX. We assemble GALEX, Johnson V, and 2MASS photometry and compare the colors of these PGR objects with those of known sd stars, cool single stars, and hot+cool binaries. Sixteen PGRs were detected in both the far- and near- ultraviolet GALEX passbands. Eleven of these, plus the 72 cases with only an upper limit in the far-ultraviolet band, are interpreted as single cool stars. Of the remaining five stars, three are consistent with being sd stars paired with a cool main sequence companion, while two may be single stars or composite systems of another type. We discuss the implications of these findings for the 1125 PGR objects as a whole. (slightly abridged)Comment: 32 pages with 3 figures and 4 tables. Uses AASTEX style files. To be published in The Astronomical Journal (August 2009 issue