3,171 research outputs found

    Efficiency considerations and the allocation of new deal funds: an examination of the public goods explanation of expenditure patterns

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    The uneven state-level distribution of New Deal spending has been frequently studied and a variety of economic and political models have been developed. In their article, “Does the Distribution of New Deal Spending Reflect an Optimal Provision of Public Goods?,†(Economics Bulletin, Vol. 8, No. 3, 2007. pp 1-5) Bateman and Taylor propose that much of the disparity in state-level New Deal expenditures can be explained if the creation of public goods and the spillover effects are included in economic models. Using the available wealth of data on New Deal programs, expenditures by agencies within the New Deal are examined and correlation statistics provided to test this hypothesis against the 1930 US census population density figures.New Deal, public good, spillover effects, Public Works Administration, PWA, Civil Works Administration, CWA

    The Three Dimensional Evolution to Core Collapse of a Massive Star

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    We present the first three dimensional (3D) simulation of the final minutes of iron core growth in a massive star, up to and including the point of core gravitational instability and collapse. We self-consistently capture the development of strong convection driven by violent Si burning in the shell surrounding the iron core. This convective burning builds the iron core to its critical (Chandrasekhar) mass and collapse ensues, driven by electron capture and photodisintegration. The non-spherical structure and motion (turbulent fluctuations) generated by 3D convection is substantial at the point of collapse. We examine the impact of such physically-realistic 3D initial conditions on the core-collapse supernova mechanism using 3D simulations including multispecies neutrino leakage. We conclude that non-spherical progenitor structure should not be ignored, and has a significant and favorable impact on the likelihood for neutrino-driven explosions.Comment: 7 pages, 5 figures, accepted for publication in ApJ Letters. Movies may be viewed at http://flash.uchicago.edu/~smc/progen3

    Optical (VRI) Photometry in the Field of the Galaxy Cluster AC 118 at z=0.31

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    We present new photometric V-, R- and I-band data for the rich galaxy cluster AC 118 at z=0.31. The new photometry covers an area of 8.6x8.6 arcmin2^2, corresponding to 2.9×\times2.9 Mpc2^2 (H0=50_0=50 km s1^{-1} Mpc1^{-1}, q0=0.5_0=0.5 and Λ=0\Lambda = 0). The data have been collected for a project aimed at studying galaxy evolution through the color-magnitude relation and the fundamental plane. We provide a catalogue including all the sources (N = 1206) detected in the cluster field. The galaxy sample is complete to V=22.8 mag (N_gal=574), R=22.3 mag (N_gal=649) and I=20.8 mag (N_gal=419). We give aperture magnitudes within a fixed aperture of 4.4 arcsec and Kron magnitudes. We also give photometric redshifts for 459 sources for which additional U- and K-band photometry is available. We derive and discuss the V- and R-band luminosity functions. The catalogue, which is distributed in electronic form, is intended as a tool for studies in galaxy evolution.Comment: 15 pages, 6 figures, A&A in pres

    Spectroscopic evolution of dusty starburst galaxies

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    By using a one-zone chemical and spectrophotometric evolution model of a disk galaxy undergoing a dusty starburst, we investigate, numerically, the optical spectroscopic properties in order to explore galaxy evolution in distant clusters. We adopt an assumption that the degree of dust extinction (represented by AVA_V) depends on the ages of starburst populations in such a way that younger stars have larger AVA_V (originally referred to as selective dust extinction by Poggianti & Wu 2000). In particular, we investigate how the time evolution of the equivalent widths of [OII]λ\lambda3727 and Hδ\delta is controlled by the adopted age dependence. This leads to three main results: (1) If a young stellar population (with the age of \sim 10610^6 yr) is more heavily obscured by dust than an old one (>> 10810^8 yr), the galaxy can show an ``e(a)'' spectrum characterized by strong Hδ\delta absorption and relatively modest [OII] emission. (2) A dusty starburst galaxy with an e(a) spectrum can evolve into a poststarburst galaxy with an a+k (or k+a) spectrum 0.2 Gyr after the starburst and then into a passive one with a k-type spectrum 1 Gyr after the starburst. This result clearly demonstrates an evolutionary link between galaxies with different spectral classes (i.e., e(b), e(a), a+k, k+a, and k). (3) A dusty starburst galaxy can show an a+k or k+a spectrum even in the dusty starburst phase if the age-dependence of dust extinction is rather weak, i.e., if young starburst populations with different ages (\le 10710^7 yr) are uniformly obscured by dust.Comment: 27 pages 12 figures,2001,ApJ,in pres

    Evidence for a Young Stellar Population in NGC 5018

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    Two absorption line indices, Ca II and Hdelta/FeI4045, measured from high resolution spectra are used with evolutionary synthesis models to verify the presence of a young stellar population in NGC 5018. The derived age of this population is about ~2.8 Gyr with a metallicity roughly solar and it completely dominates the integrated light of the galaxy near 4000 A.Comment: 13 pages, 7 figures (figs 3-7 are color figures), to be published in the May 2000 issue of the Astrophysical Journa

    The Scientific Teaching Practices Survey for Undergraduate STEM Courses

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    The National Academies Summer Institutes on Undergraduate Education (SI) is a faculty development workshop in which STEM instructors are trained in the Scientific Teaching (ST) pedagogy and encouraged to implement its practices at their home institutions. While participants generally report positive experiences at the SI, it remains unclear how these experiences affect instructors’ teaching practices and associated student outcomes. As part of a larger effort to evaluate the SI, we developed a survey to gauge the frequencies of ST practices that could occur in undergraduate STEM courses. The ST Practices Survey is derived from the observable teaching practices described in the Scientific Teaching taxonomy (Couch et al., 2015). During survey development, we conducted interviews with a panel of experts, instructors, and students, and this input was used to make iterative revisions to the survey. After finalizing the survey, we administered the survey at 9 institutions with 62 instructors and 64 courses, with both instructors and students completing the survey for a given course. In this seminar, we will discuss the development, validity, reliability, factor structure, and implementation of the ST Practices Survey. (abstract only

    The Scientific Teaching Practices Survey for Undergraduate STEM Courses

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    The National Academies Summer Institutes on Undergraduate Education (SI) is a faculty development workshop in which STEM instructors are trained in the Scientific Teaching (ST) pedagogy and encouraged to implement its practices at their home institutions. While participants generally report positive experiences at the SI, it remains unclear how these experiences affect instructors’ teaching practices and associated student outcomes. As part of a larger effort to evaluate the SI, we developed a survey to gauge the frequencies of ST practices that could occur in undergraduate STEM courses. The ST Practices Survey is derived from the observable teaching practices described in the Scientific Teaching taxonomy (Couch et al., 2015). During survey development, we conducted interviews with a panel of experts, instructors, and students, and this input was used to make iterative revisions to the survey. After finalizing the survey, we administered the survey at 9 institutions with 62 instructors and 64 courses, with both instructors and students completing the survey for a given course. In this seminar, we will discuss the development, validity, reliability, factor structure, and implementation of the ST Practices Survey. (abstract only

    New Deal Agricultural Appropriations: A Political Influence

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    This study investigates the allocation of New Deal appropriations to agricultural interests in Alabama's sixty-seven counties during the Great Depression. Conventional wisdom indicates that Roosevelt, through the New Deal, brought assistance to those in need. However, recent literature has identified a political motivation to the pattern of spending that emerged during the economic downturn. The authors develop and estimate a model with data which has only recently become available. The results show that while communities with the highest farm income received larger appropriations as expected, counties that experienced a collapse in farm income during the Great Depression received no special consideration from those officials responsible for distributing New Deal dollars across the state. These results indicate that self-interest was an important motivator in allocating agricultural appropriations in the state of Alabama during the Great Depression.Depression

    Optical Spectral Signatures of Dusty Starburst Galaxies

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    We analyse the optical spectral properties of the complete sample of Very Luminous Infrared Galaxies presented by Wu et al. (1998a,b) and we find a high fraction (~50 %) of spectra showing both a strong H_delta line in absorption and relatively modest [OII] emission (e(a) spectra). The e(a) signature has been proposed as an efficient method to identify dusty starburst galaxies and we study the star formation activity and the nature of these galaxies, as well as the effects of dust on their observed properties. We examine their emission line characteristics, in particular their [OII]/H_alpha ratio, and we find this to be greatly affected by reddening. A search for AGN spectral signatures reveals that the e(a)'s are typically HII/LINER galaxies. We compare the star formation rates derived from the FIR luminosities with the estimates based on the H_alpha line and find that the values obtained from the optical emission lines are a factor of 10-70 (H_alpha) and 20-140 ([OII]) lower than the FIR estimates (50-300 M_sun yr^-1). We then study the morphological properties of the e(a) galaxies, looking for a near companion or signs of a merger/interaction. In order to explore the evolution of the e(a) population, we present an overview of the available observations of e(a)'s in different environments both at low and high redshift. Finally, we discuss the role of dust in determining the e(a) spectral properties and we propose a scenario of selective obscuration in which the extinction decreases with the stellar age.Comment: 26 pages, Latex, including 7 postscript figures, accepted for publication in the Astrophysical Journa
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