778 research outputs found

    Galaxy-Galaxy Lensing in the Hubble Deep Field: The Halo Tully-Fisher Relation at Intermediate Redshift

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    A tangential distortion of background source galaxies around foreground lens galaxies in the Hubble Deep Field is detected at the 99.3% confidence level. An important element of our analysis is the use of photometric redshifts to determine distances of lens and source galaxies and rest-frame B-band luminosities of the lens galaxies. The lens galaxy halos obey a Tully-Fisher relation between halo circular velocity and luminosity; the typical lens galaxy, at a redshift z = 0.6, has a circular velocity of 210 +/-40 km/s at M_B = -18.5, if q_0 = 0.5. Control tests, in which lens and source positions and source ellipticities are randomized, confirm the significance level of the detection quoted above. Furthermore, a marginal signal is also detected from an independent, fainter sample of source galaxies without photometric redshifts. Potential systematic effects, such as contamination by aligned satellite galaxies, the distortion of source shapes by the light of the foreground galaxies, PSF anisotropies, and contributions from mass distributed on the scale of galaxy groups are shown to be negligible. A comparison of our result with the local Tully-Fisher relation indicates that intermediate-redshift galaxies are fainter than local spirals by 1.0 +/- 0.6 B mag at a fixed circular velocity. This is consistent with some spectroscopic studies of the rotation curves of intermediate-redshift galaxies. This result suggests that the strong increase in the global luminosity density with redshift is dominated by evolution in the galaxy number density.Comment: Revised version with minor changes. 13 pages, 7 figures, LaTeX2e, uses emulateapj and multicol styles (included). Accepted by Ap

    Estimation of Farm-Forward Regional Economic Impacts for the North Plains Groundwater Conservation District in Texas

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    Impacts of alternative agricultural water conservation strategies are being evaluated in the Texas Panhandle. Stakeholders have expressed concern that all effects need to be accounted for including the regional economy. A methodology was developed to evaluate the effects on the backward and forward-linked processing sectors and differentiated results are presented.backward-linked, forward-linked, IMPLAN, Ogallala Aquifer, water policy, Resource /Energy Economics and Policy, Q18, Q32, Q38,

    AMPK Regulation of Mouse Oocyte Meiotic Resumption in Vitro

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    We have previously shown that the adenosine analog 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR), an activator of AMP-activated protein kinase (AMPK), stimulates an increase in AMPK activity and induces meiotic resumption in mouse oocytes [Downs, S.M., Hudson, E.R., Hardie, D.G., 2002. A potential role for AMP-activated protein kinase in meiotic induction in mouse oocytes. Dev. Biol, 245, 200–212]. The present study was carried out to better define a causative role for AMPK in oocyte meiotic maturation. When microinjected with a constitutively active AMPK, about 20% of mouse oocytes maintained in meiotic arrest with dibutyryl cAMP (dbcAMP) were stimulated to undergo germinal vesicle breakdown (GVB), while there was no effect of catalytically dead kinase. Western blot analysis revealed that germinal vesicle (GV)-stage oocytes cultured in dbcAMP-containing medium plus AICAR possessed elevated levels of active AMPK, and this was confirmed by AMPK assays using a peptide substrate of AMPK to directly measure AMPK activity. AICAR-induced meiotic resumption and AMPK activation were blocked by compound C or adenine 9-beta-d-arabinofuranoside (araA, a precursor of araATP), both inhibitors of AMPK. Compound C failed to suppress adenosine uptake and phosphorylation, indicating that it did not block AICAR action by preventing its metabolism to the AMP analog, ZMP. 2′-Deoxycoformycin (DCF), a potent adenosine deaminase inhibitor, reversed the inhibitory effect of adenosine on oocyte maturation by modulating intracellular AMP levels and activating AMPK. Rosiglitazone, an anti-diabetic agent, stimulated AMPK activation in oocytes and triggered meiotic resumption. In spontaneously maturing oocytes, GVB was preceded by AMPK activation and blocked by compound C. Collectively, these results support the proposition that active AMPK within mouse oocytes provides a potent meiosis-inducing signal in vitro

    Investigation of Systematic Bias in Radiometric Diameter Determination of Near-Earth Asteroids: the Night Emission Simulated Thermal Model (NESTM)

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    The Near-Earth Asteroid Thermal Model (NEATM, Harris, 1998) has proven to be a reliable simple thermal model for radiometric diameter determination. However NEATM assumes zero thermal emission on the night side of an asteroid. We investigate how this assumption affects the best-fit beaming parameter, overestimates the effective diameter and underestimates the albedo at large phase angles, by testing NEATM on thermal IR fluxes generated from simulated asteroid surfaces with different thermal inertia. We compare NEATM to radar diameters and find that NEATM overestimates the diameter when the beaming parameter is fitted to multi-wavelength observations and underestimates the diameter when the default beaming parameter is used. The Night Emission Simulated Thermal Model (NESTM) is introduced. NESTM models the night side temperature as an iso-latitudinal fraction (f) of the maximum day side temperature (Maximum temperature calculated for NEATM with beaming parameter = 1). A range of f is found for different thermal parameters, which depend on the thermal inertia. NESTM diameters are compared with NEATM and radar diameters, and it is shown that NESTM may reduce the systematic bias in overestimating diameters. It is suggested that a version of the NESTM which assumes the thermal inertia = 200 S.I. units is adopted as a default model when the solar phase angle is greater than 45 degrees.Comment: 48 pages, 10 Figures, 5 Table

    The Vehicle, 1966, Vol. 8

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    Vol. 8 Table of Contents CommentaryBill Moser & Avis Eaglestonpage 3 The Vengeance of the DeadStephen W. Gibbspage 5 Ode To A MeadowKathleen McCormackpage 12 Row OnDavid Helmpage 13 Sonnet 63R.L. Hudsonpage 14 UntitledKathleen McCormackpage 14 The Pure GoldDavid Helmpage 15 CommunionDavid Helmpage 15 PreludeMichael Baldwinpage 15 The AlbatrossKaren Cooleypage 16 The Albatross (photo)DeWittpage 17 Ruff and the VaseDavid Helmpage 18 LaBelleKathleen McCormackpage 19 Not Quite SoR.L. Hudsonpage 20 Feeling (no number)David Reifpage 21 Song at DuskDavid Helmpage 21 Arcadia RuminationsR.L. Hudsonpage 22 The BarWayne Johnsonpage 25 HelloWilliam Framepage 26 The ProcessJerry DeWittpage 27 The KillingAdrian Beardpage 30 The Amusement Park GameStephen W. Gibbspage 38 DamnMel Tylerpage 40 PainWilliam Framepage 40 UntitledSusan Champlinpage 41 Portrait of A Scholar As A Young ManStephen W. Gibbspage 42 The TimesW.D.Mpage 46 ParadoxW.D.M.page 46 MankindDavid Helmpage 47https://thekeep.eiu.edu/vehicle/1014/thumbnail.jp

    The Vehicle, 1966, Vol. 8

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    Vol. 8 Table of Contents CommentaryBill Moser & Avis Eaglestonpage 3 The Vengeance of the DeadStephen W. Gibbspage 5 Ode To A MeadowKathleen McCormackpage 12 Row OnDavid Helmpage 13 Sonnet 63R.L. Hudsonpage 14 UntitledKathleen McCormackpage 14 The Pure GoldDavid Helmpage 15 CommunionDavid Helmpage 15 PreludeMichael Baldwinpage 15 The AlbatrossKaren Cooleypage 16 The Albatross (photo)DeWittpage 17 Ruff and the VaseDavid Helmpage 18 LaBelleKathleen McCormackpage 19 Not Quite SoR.L. Hudsonpage 20 Feeling (no number)David Reifpage 21 Song at DuskDavid Helmpage 21 Arcadia RuminationsR.L. Hudsonpage 22 The BarWayne Johnsonpage 25 HelloWilliam Framepage 26 The ProcessJerry DeWittpage 27 The KillingAdrian Beardpage 30 The Amusement Park GameStephen W. Gibbspage 38 DamnMel Tylerpage 40 PainWilliam Framepage 40 UntitledSusan Champlinpage 41 Portrait of A Scholar As A Young ManStephen W. Gibbspage 42 The TimesW.D.Mpage 46 ParadoxW.D.M.page 46 MankindDavid Helmpage 47https://thekeep.eiu.edu/vehicle/1014/thumbnail.jp

    Genomic signatures of population decline in the malaria mosquito Anopheles gambiae

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    Population genomic features such as nucleotide diversity and linkage disequilibrium are expected to be strongly shaped by changes in population size, and might therefore be useful for monitoring the success of a control campaign. In the Kilifi district of Kenya, there has been a marked decline in the abundance of the malaria vector Anopheles gambiae subsequent to the rollout of insecticide-treated bed nets. To investigate whether this decline left a detectable population genomic signature, simulations were performed to compare the effect of population crashes on nucleotide diversity, Tajima's D, and linkage disequilibrium (as measured by the population recombination parameter ρ). Linkage disequilibrium and ρ were estimated for An. gambiae from Kilifi, and compared them to values for Anopheles arabiensis and Anopheles merus at the same location, and for An. gambiae in a location 200 km from Kilifi. In the first simulations ρ changed more rapidly after a population crash than the other statistics, and therefore is a more sensitive indicator of recent population decline. In the empirical data, linkage disequilibrium extends 100-1000 times further, and ρ is 100-1000 times smaller, for the Kilifi population of An. gambiae than for any of the other populations. There were also significant runs of homozygosity in many of the individual An. gambiae mosquitoes from Kilifi. These results support the hypothesis that the recent decline in An. gambiae was driven by the rollout of bed nets. Measuring population genomic parameters in a small sample of individuals before, during and after vector or pest control may be a valuable method of tracking the effectiveness of interventions
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