612 research outputs found

    The Status of Utah\u27s Agriculture and its Contribution to the State Economy

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    Growth in agricultural productivity and the migration of labor from agriculture to other employment has been a source of growth for the whole economy. From the times of pioneer settlement in Utah, more than 130 years ago, agricultural production has declined as a proportion of total economic activity. Employment, personal income, gross sales, and other measures can be shown to have declined as a proportion of the totals of these measures for the state. Yet, it is this very decline in dependence on workers producing food that has helped the economy to grow in size and variety both in Utah and throughout the nation

    Space Velocities of Southern Globular Clusters. IV. First Results for Inner-Galaxy Clusters

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    We have measured the absolute proper motions of four low-latitude, inner-Galaxy globular clusters. These clusters are: NGC 6266 (M62), NGC 6304, NGC 6316 and NGC 6723. The proper motions are on the Hipparcos system, as no background extragalactic objects are found in these high-extinction regions. The proper-motion uncertainties range between 0.3 and 0.6 mas/yr. We discuss the kinematics of these clusters and of three additional bulge clusters -- NGC 6522, NGC 6528 and NFC 6553 -- whose proper motions with respect to bulge stars had been determined previously. We find that all of the clusters have velocities that confine them to the bulge region. Of the three metal poor clusters ([Fe/H] < -1.0), NGC 6522, and NGC 6723 have kinematics consistent with halo membership. The third cluster, NGC 6266 however, appears to belong to a rotationally-supported system. Of the four metal rich clusters ([Fe/H] >= -1.0), NGC 6304 and NGC 6553 also have kinematics consistent with membership to a rotationally-supported system. NGC 6528 has kinematics, metallicity and mass that argue in favor of a genuine Milky-Way bar cluster. NGC 6316's kinematics indicate membership to a hotter system than the bar.Comment: 4 figures, 5 tables; accepted for publication in A

    A large local rotational speed for the Galaxy found from proper-motions: Implications for the mass of the Milky-Way

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    Predictions from a Galactic Structure and Kinematic model are compared to the absolute proper-motions of about 30,000 randomly selected stars with 9<BJ≀199 < B_{\rm J} \le 19 derived from the Southern Proper-Motion Program (SPM) toward the South Galactic Pole. The absolute nature of the SPM proper-motions allow us to measure not only the relative motion of the Sun with respect to the local disk, but also, and most importantly, the overall state of rotation of the local disk with respect to galaxies. The SPM data are best fit by models having a solar peculiar motion of +5 km~s−1^{-1} in the V-component (pointing in the direction of Galactic rotation), a large LSR speed of 270 km~s−1^{-1}, and a disk velocity ellipsoid that points towards the Galactic center. We stress, however, that these results rest crucially on the assumptions of both axisymmetry and equilibrium dynamics. The absolute proper-motions in the U-component indicate a solar peculiar motion of 11.0±1.511.0 \pm 1.5 km~s−1^{-1}, with no need for a local expansion or contraction term. The implications of the large LSR speed are discussed in terms of gravitational mass of the Galaxy inferred from the most recent and accurate determination for the proper-motion of the LMC. We find that our derived value for the LSR is consistent both with the mass of the Galaxy inferred from the motion of the Clouds (3−4×1012M⊙3 - 4 \times 10^{12} M_\odot to ∌50\sim 50 kpc), as well as the timing argument, based on the binary motion of M31 and the Milky Way, and Leo I and the Milky Way (≄1.2×1012M⊙\ge 1.2 \times 10^{12} M_\odot to ∌200\sim 200 kpc).Comment: 7 pages (AAS Latex macro v4.0), 2 B&W postscript figures, accepted for publication on ApJ, Letters sectio

    Absolute Proper Motion of the Fornax Dwarf Spheroidal Galaxy from Photographic and HST WFPC2 Data

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    We have measured the absolute proper motion of the Fornax dwarf spheroidal galaxy from a combination of photographic plate material and HST WFPC2 data that provide a time baseline of up to 50 years. The extragalactic reference frame consists of 8 QSO images and 48 galaxies. The absolute proper motion is mu_alpha cos(delta) = 0.59 +-0.16 mas/yr and mu_delta = -0.15 +- 0.16 mas/yr. The corresponding orbit of Fornax is polar, with an eccentricity of 0.27, and a radial period of 4.5 Gyr. Fornax's current location is near pericenter. The direction of the motion of Fornax supports the notion that Fornax belongs to the Fornax-LeoI-LeoII-Sculptor-Sextans stream as hypothesized by Lynden-Bell (1976, 1982) and Majewski (1994). According to our orbit determination, Fornax crossed the Magellanic plane \~190 Myr ago, a time that coincides with the termination of the star-formation process in Fornax. We propose that ram-pressure stripping due to the passage of Fornax through a gaseous medium denser than the typical intragalactic medium left behind from the LMC may have caused the end of star formation in Fornax. The excess, anomalous clouds within the South Galactic pole region of the Magellanic Stream whose origin has long been debated in the literature as constituents of either the Magellanic Stream or of the extragalactic Sculptor group, are found to lie along the orbit of Fornax. We speculate that these clouds are stripped material from Fornax as the dwarf crossed the Magellanic Clouds' orbit.Comment: Accepted for publication in Astronomical Journal. The version with high resolution figures can be found at ftp://pegasus.astro.yale.edu/pub/dana/paper

    Use of Shared Faculty in U.S. and Canadian Dental Schools

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    Dental schools are facing substantial financial challenges and a shortage of faculty members. One solution to address these issues has been to hire “shared” faculty members, i.e., faculty members whose primary appointment is at one institution who are hired by another institution to teach a course or part of a course. This is a controversial concept. A survey of academic deans at U.S. and Canadian dental schools was conducted for this study; thirty-nine (54 percent) of the seventy-two academic deans completed the online survey. This survey found that the use of shared faculty members is not rare amongst U.S. and Canadian dental schools and that the opinions of the academic deans about the use of shared faculty members ranged widely—from strong support to strong disapproval. Using shared faculty members has advantages and disadvantages for students, the shared faculty members, and both institutions. Many of the disadvantages could be potentially minimized by stakeholders’ working together to develop collaborative arrangements. Networks could be developed in which institutions coordinate hiring of shared faculty members based on what expertise is needed. Financial challenges and shortages of faculty members are unlikely to be resolved in the near future, but use of shared faculty members is one promising approach to begin to meet these challenges

    Galactic Kinematics Towards the South Galactic Pole. First Results from the Yale-San Juan Southern Proper-Motion Program

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    The predictions from a Galactic Structure and Kinematic model code are compared to the color counts and absolute proper-motions derived from the Southern Proper-Motion survey covering more than 700 deg⁥2\deg^2 toward the South Galactic Pole in the range 9<BJ≀199 < B_{\rm J} \le 19. The theoretical assumptions and associated computational procedures, the geometry for the kinematic model, and the adopted parameters are presented in detail and compared to other Galactic Kinematic models of its kind. The data to which the model is compared consists of more than 30,000 randomly selected stars, and it is best fit by models with a solar peculiar motion of +5 km s−1^{-1} in the V-component (pointing in the direction of Galactic rotation), a large LSR speed of 270 km s−1^{-1}, and a (disk) velocity ellipsoid that always points towards the Galactic center. The absolute proper-motions in the U-component indicate a solar peculiar motion of 11.0±1.511.0 \pm 1.5 km s−1^{-1}, with no need for a local expansion or contraction term. The fainter absolute motions show an indication that the thick-disk must exhibit a rather steep velocity gradient of about -36 km s−1^{-1} kpc−1^{-1} with respect to the LSR. We are not able to set constraints on the overall rotation for the halo, nor on the thick-disk or halo velocity dispersions. Some substructure in the U & V proper-motions could be present in the brighter bins 10<BJ<1310 < B_{\rm J} < 13, and it might be indicative of (disk) moving groups.Comment: 24 double-column pages, 12 tables, AAS Latex macros v4.0, 19 B&W figures, 1 color figure. Accepted for publication on The Astronomical Journa

    Proper Motions in the Galactic Bulge: Plaut's Window

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    A proper motion study of a field of 20' x 20' inside Plaut's low extinction window (l,b)=(0 deg,-8 deg), has been completed. Relative proper motions and photographic BV photometry have been derived for ~21,000 stars reaching to V~20.5 mag, based on the astrometric reduction of 43 photographic plates, spanning over 21 years of epoch difference. Proper motion errors are typically 1 mas/yr and field dependent systematics are below 0.2 mas/yr. Cross-referencing with the 2MASS catalog yielded a sample of ~8,700 stars, from which predominantly disk and bulge subsamples were selected photometrically from the JH color-magnitude diagram. The two samples exhibited different proper-motion distributions, with the disk displaying the expected reflex solar motion as a function of magnitude. Galactic rotation was also detected for stars between ~2 and ~3 kpc from us. The bulge sample, represented by red giants, has an intrinsic proper motion dispersion of (sigma_l,sigma_b)=(3.39, 2.91)+/-(0.11,0.09) mas/yr, which is in good agreement with previous results, and indicates a velocity anisotropy consistent with either rotational broadening or tri-axiality. A mean distance of 6.37^{+0.87}_{-0.77} kpc has been estimated for the bulge sample, based on the observed K magnitude of the horizontal branch red clump. The metallicity [M/H] distribution was also obtained for a subsample of 60 bulge giants stars, based on calibrated photometric indices. The observed [M/H] shows a peak value at [M/H]~-0.1 with an extended metal poor tail and around 30% of the stars with supersolar metallicity. No change in proper motion dispersion was observed as a function of [M/H]. We are currently in the process of obtaining CCD UBVRI photometry for the entire proper-motion sample of ~21,000 stars.Comment: Submitted to AJ April 17th 2007. Accepted June 8th 2007. 45 pages, 14 figure

    A calculation of the BBB_{B} parameter in the static limit

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    We calculate the BBB_{B} parameter, relevant for B‟0\overline{B}^0 -- B0B^0 mixing, from a lattice gauge theory simulation at ÎČ=6.0\beta = 6.0. The bottom quarks are simulated in the static theory, the light quarks with Wilson fermions. Improved smearing functions produced by a variational technique, MOST, are used to reduce statistical errors and minimize excited-state contamination of the ground-state signal. We obtain BB(4.33GeV)=0.98−4+4B_B(4.33 GeV) = 0.98^{+4}_{-4} (statistical) −18+3^{+3}_{-18} (systematic) which corresponds to B^B=1.40−6+6\widehat{B}_B = 1.40^{+6}_{-6} (statistical) −26+4^{+4}_{-26} (systematic) for the one-loop renormalization-scheme-independent parameter. The systematic errors include the uncertainty due to alternative (less favored) treatments of the perturbatively-calculated mixing coefficients; this uncertainty is at least as large as residual differences between Wilson-static and clover-static results. Our result agrees with extrapolations of results from relativistic (Wilson) heavy quark simulations.Comment: 39 pages (REVTeX) including 10 figures (PostScript); Final version accepted for publication: Added new section for clarity; Included comparison to recent results by other groups; slight numerical changes; Essential conclusions remain the sam

    Proper Motions in Kapteyn Selected Area 103: A Preliminary Orbit for the Virgo Stellar Stream

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    We present absolute proper motions in Kapteyn Selected Area (SA) 103. This field is located 7 degrees west of the center of the Virgo Stellar Stream (VSS, Duffau et al. 2006), and has a well-defined main sequence representing the stream. In SA 103 we identify one RR Lyrae star as a member of the VSS according to its metallicity, radial velocity and distance. VSS candidate turnoff stars and subgiant stars have proper motions consistent with that of the RR Lyrae star. The 3D velocity data imply an orbit with a pericenter of 11 kpc and an apocenter of ~90 kpc. Thus, the VSS comprises tidal debris found near the pericenter of a highly destructive orbit. Examining the six globular clusters at distances larger than 50 kpc from the Galactic center, and the proposed orbit of the VSS, we find one tentative association, NGC 2419. We speculate that NGC 2419 is possibly the nucleus of a disrupted system of which the VSS is a part.Comment: ApJL accepte
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