1,005 research outputs found

    REGIONAL AND NATIONAL IMPACTS OF EXPANDED PACIFIC NORTHWEST POTATO PRODUCTION

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    A 46-equation econometric model of the U.S. potato market was developed. The model examines the determination of planted acreage, yield, production, and farm prices in the Pacific Northwest and in five other producing regions which compete with Northwest production. National demand relationships for potatoes used in processing, fresh consumption and livestock feed are also specified. These estimated relationships are used to simulate future scenarios which assume alternative rates of expansion for Northwest potato production. Results suggest that opportunities for considerable expansion of Northwest potato production exist if the secular shift in potato demand continues and increases in acreage are not excessive or expansion does not occur too quickly.Crop Production/Industries,

    A First Comparison of the SBF Survey Distances with the Galaxy Density Field: Implications for H_0 and Omega

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    We compare the peculiar velocities measured in the SBF Survey of Galaxy Distances with the predictions from the density fields of the IRAS 1.2 Jy flux-limited redshift survey and the Optical Redshift Survey (ORS) to derive simultaneous constraints on the Hubble constant H0H_0 and the density parameter β=Ω0.6/b\beta = \Omega^{0.6}/b, where bb is the linear bias. We find βI=0.42−0.06+0.10\beta_I=0.42^{+0.10}_{-0.06} and βO=0.26±0.08\beta_O=0.26\pm0.08 for the IRAS and ORS comparisons, respectively, and H0=74±4H_0=74\pm4 \kmsMpc (with an additional 9% uncertainty due to the Cepheids themselves). The match between predicted and observed peculiar velocities is good for these values of H0H_0 and β\beta, and although there is covariance between the two parameters, our results clearly point toward low-density cosmologies. Thus, the unresolved discrepancy between the ``velocity-velocity'' and ``density-density'' measurements of β\beta continues.Comment: 4 pages with 3 embedded ps figures; uses emulateapj.sty (included). Accepted for publication in ApJ Letter

    Reconciliation of the Surface Brightness Fluctuations and Type Ia Supernovae Distance Scales

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    We present Hubble Space Telescope measurements of surface brightness fluctuations (SBF) distances to early-type galaxies that have hosted Type Ia supernovae (SNIa). The agreement in the relative SBF and SNIa multicolor light curve shape and delta-m_15 distances is excellent. There is no systematic scale error with distance, and previous work has shown that SBF and SNIa give consistent ties to the Hubble flow. However, we confirm a systematic offset of about 0.25 mag in the distance zero points of the two methods, and we trace this offset to their respective Cepheid calibrations. SBF has in the past been calibrated with Cepheid distances from the H_0 Key Project team, while SNIa have been calibrated with Cepheid distances from the team composed of Sandage, Saha, and collaborators. When the two methods are calibrated in a consistent way, their distances are in superb agreement. Until the conflict over the ``long'' and ``short'' extragalactic Cepheid distances among many galaxies is resolved, we cannot definitively constrain the Hubble constant to better than about 10%, even leaving aside the additional uncertainty in the distance to the Large Magellanic Cloud, common to both Cepheid scales. However, recent theoretical SBF predictions from stellar population models favor the Key Project Cepheid scale, while the theoretical SNIa calibration lies between the long and short scales. In addition, while the current SBF distance to M31/M32 is in good agreement with the RR Lyrae and red giant branch distances, calibrating SBF with the longer Cepheid scale would introduce a 0.3 mag offset with respect to the RR Lyrae scale.Comment: 13 pages, 3 PostScript figures, LaTeX with AASTeX 5.02 and natbib.sty v7.0 (included). Accepted for publication in The Astrophysical Journa

    The MASSIVE Survey - VIII. Stellar Velocity Dispersion Profiles and Environmental Dependence of Early-Type Galaxies

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    We measure the radial profiles of the stellar velocity dispersions, σ(R)\sigma(R), for 90 early-type galaxies (ETGs) in the MASSIVE survey, a volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all northern-sky ETGs with absolute KK-band magnitude MK<−25.3M_K < -25.3 mag, or stellar mass M∗>4×1011M⊙M_* > 4 \times 10^{11} M_\odot, within 108 Mpc. Our wide-field 107" ×\times 107" IFS data cover radii as large as 40 kpc, for which we quantify separately the inner (2 kpc) and outer (20 kpc) logarithmic slopes γinner\gamma_{\rm inner} and γouter\gamma_{\rm outer} of σ(R)\sigma(R). While γinner\gamma_{\rm inner} is mostly negative, of the 56 galaxies with sufficient radial coverage to determine γouter\gamma_{\rm outer} we find 36% to have rising outer dispersion profiles, 30% to be flat within the uncertainties, and 34% to be falling. The fraction of galaxies with rising outer profiles increases with M∗M_* and in denser galaxy environment, with 10 of the 11 most massive galaxies in our sample having flat or rising dispersion profiles. The strongest environmental correlations are with local density and halo mass, but a weaker correlation with large-scale density also exists. The average γouter\gamma_{\rm outer} is similar for brightest group galaxies, satellites, and isolated galaxies in our sample. We find a clear positive correlation between the gradients of the outer dispersion profile and the gradients of the velocity kurtosis h4h_4. Altogether, our kinematic results suggest that the increasing fraction of rising dispersion profiles in the most massive ETGs are caused (at least in part) by variations in the total mass profiles rather than in the velocity anisotropy alone.Comment: Accepted/in press, MNRA

    The SBF Survey of Galaxy Distances. I. Sample Selection, Photometric Calibration, and the Hubble Constant

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    We describe a program of surface brightness fluctuation (SBF) measurements for determining galaxy distances. This paper presents the photometric calibration of our sample and of SBF in general. Basing our zero point on observations of Cepheid variable stars, we find that the absolute SBF magnitude in the Kron-Cousins I band correlates well with the mean (V-I)o color of a galaxy according to M_Ibar = (-1.74 +/- 0.07) + (4.5 +/- 0.25) [ (V-I)o - 1.15 ] for 1.0 < (V-I) < 1.3. This agrees well with theoretical estimates from stellar population models. Comparisons between SBF distances and a variety of other estimators, including Cepheid variable stars, the Planetary Nebula Luminosity Function (PNLF), Tully-Fisher (TF), Dn-sigma, SNII, and SNIa, demonstrate that the calibration of SBF is universally valid and that SBF error estimates are accurate. The zero point given by Cepheids, PNLF, TF (both calibrated using Cepheids), and SNII is in units of Mpc; the zero point given by TF (referenced to a distant frame), Dn-sigma and SNIa is in terms of a Hubble expansion velocity expressed in km/s. Tying together these two zero points yields a Hubble constant of H_0 = 81 +/- 6 km/s/Mpc. As part of this analysis, we present SBF distances to 12 nearby groups of galaxies where Cepheids, SNII, and SNIa have been observed.Comment: 29 pages plus 8 figures; LaTeX (AASTeX) uses aaspp4.sty (included); To appear in The Astrophysical Journal, 1997 February 1 issue; Compressed PostScript available from ftp://mars.tuc.noao.edu/sbf

    Slow, Steady-State Transport with "Loading" and Bulk Reactions: the Mixed Ionic Conductor La2_2CuO4+δ_{4+\delta}

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    We consider slow, steady transport for the normal state of the superconductor La2_2CuO4+δ_{4+\delta} in a one-dimensional geometry, with surface fluxes sufficiently general to permit oxygen to be driven into the sample (``loaded'') either by electrochemical means or by high oxygen partial pressure. We include the bulk reaction O→\toO2−+2h^{2-}+2h, where neutral atoms (aa) go into ions (ii) and holes (hh). For slow, steady transport, the transport equations simplify because the bulk reaction rate density rr and the bulk loading rates ∂tn\partial_t n then are uniform in space and time. All three fluxes jj must be specified at each surface, which for a uniform current density JJ corresponds to five independent fluxes. These fluxes generate two types of static modes at each surface and a bulk response with a voltage profile that varies quadratically in space, characterized by JJ and the total oxygen flux jOj_O (neutral plus ion) at each surface. One type of surface mode is associated with electrical screening; the other type is associated both with diffusion and drift, and with chemical reaction (the {\it diffusion-reaction mode}). The diffusion-reaction mode is accompanied by changes in the chemical potentials μ\mu, and by reactions and fluxes, but it neither carries current (J=0) nor loads the system chemically (jO=0j_O=0). Generation of the diffusion-reaction mode may explain the phenomenon of ``turbulence in the voltage'' often observed near the electrodes of other mixed ionic electronic conductors (MIECs).Comment: 11 pages, 1 figur

    The SBF Survey of Galaxy Distances. II. Local and Large-Scale Flows

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    We present analysis of local large scale flows using the Surface Brightness Fluctuation (SBF) Survey for the distances to 300 early-type galaxies. Our models of the distribution function of mean velocity and velocity dispersion at each point in space include a uniform thermal velocity dispersion and spherical attractors whose position, amplitude, and radial shape are free to vary. Our fitting procedure performs a maximum likelihood fit of the model to the observations. We obtain a Hubble constant of Ho = 77 +/- 4 +/- 7 km/s/Mpc, but a uniform Hubble flow is not acceptable fit to the data. Inclusion of two attractors, one of whose fit location coincides with the Virgo cluster and the other whose fit location is slightly beyond the Centaurus clusters nearly explain the peculiar velocities, but the quality of the fit can be further improved by the addition of a quadrupole correction to the Hubble flow. Although the dipole and quadrupole may be genuine manifestations of more distant density fluctuations, we find evidence that they are more likely due to non-spherical attractors. We find no evidence for bulk flows which include our entire survey volume (R < 3000 km/s); our volume is at rest with respect to the CMB. The fits to the attractors both have isothermal radial profiles (v ~ 1/r) over a range of overdensity between about 10 and 1, but fall off more steeply at larger radius. The best fit value for the small scale, cosmic thermal velocity is 180 +/- 14 km/s.Comment: 37 pages, AASTeX Latex, including 30 Postscript figures, submitted to Astrophysical Journal, July 2, 199
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