576 research outputs found

    The "new" quantitative history: social science or old wine in new bottles? (1980)

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    The "new" quantitative history: social science or old wine in new bottles?

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    Der Autor stellt Ansätze der quantifizierenden historischen Forschung in den USA vor, die einen Fortschritt auf dem Weg zu einer sozialwissenschaftlichen Geschichtswissenschaft darstellen. Auch bei der Übernahme sozialwissenschaftlicher Methoden bleiben die ursprünglichen Ziele der Historiographie erhalten. Für die Anfänge dieser Entwicklung konstatiert der Autor eine Vernachlässigung konzeptioneller Fragen zugunsten der reinen Datenerhebung. Für ihn ist die Entwicklung in der neuen ökonomischen Geschichte am weitesten fortgeschritten, die von einem neoklassischen Ansatz ausgeht. (BG

    Is Instrumental Music In Christian Worship Scriptural?

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    https://digitalcommons.acu.edu/crs_books/1389/thumbnail.jp

    How long is a hillslope?

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    Hillslope length is a fundamental attribute of landscapes, intrinsically linked to drainage density, landslide hazard, biogeochemical cycling and hillslope sediment transport. Existing methods to estimate catchment average hillslope lengths include inversion of drainage density or identification of a break in slope–area scaling, where the hillslope domain transitions into the fluvial domain. Here we implement a technique which models flow from point sources on hilltops across pixels in a digital elevation model (DEM), based on flow directions calculated using pixel aspect, until reaching the channel network, defined using recently developed channel extraction algorithms. Through comparisons between these measurement techniques, we show that estimating hillslope length from plots of topographic slope versus drainage area, or by inverting measures of drainage density, systematically underestimates hillslope length. In addition, hillslope lengths estimated by slope–area scaling breaks show large variations between catchments of similar morphology and area. We then use hillslope length–relief structure of landscapes to explore nature of sediment flux operating on a landscape. Distinct topographic forms are predicted for end-member sediment flux laws which constrain sediment transport on hillslopes as being linearly or nonlinearly dependent on hillslope gradient. Because our method extracts hillslope profiles originating from every ridgetop pixel in a DEM, we show that the resulting population of hillslope length–relief measurements can be used to differentiate between linear and nonlinear sediment transport laws in soil mantled landscapes. We find that across a broad range of sites across the continental United States, topography is consistent with a sediment flux law in which transport is nonlinearly proportional to topographic gradient

    Late-Time Circumstellar Interaction in a Spitzer Selected Sample of Type IIn Supernovae

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    Type IIn supernovae (SNe IIn) are a rare (< 10%) subclass of core-collapse SNe that exhibit relatively narrow emission lines from a dense, pre-existing circumstellar medium (CSM). In 2009, a warm Spitzer survey observed 30 SNe IIn discovered in 2003 - 2008 and detected 10 SNe at distances out to 175 Mpc with unreported late-time infrared emission, in some cases more than 5 years post-discovery. For this single epoch of data, the warm-dust parameters suggest the presence of a radiative heating source consisting of optical/X-ray emission continuously generated by ongoing CSM interaction. Here we present multi-wavelength follow-up observations of this sample of 10 SNe IIn and the well-studied Type IIn SN 2010jl. A recent epoch of Spitzer observations reveals ongoing mid-infrared emission from nine of the SNe in this sample. We also detect three of the SNe in archival WISE data, in addition to SNe 1987A, 2004dj, and 2008iy. For at least five of the SNe in the sample, optical and/or X-ray emission confirms the presence of radiative emission from ongoing CSM interaction. The two Spitzer nondetections are consistent with the forward shock overrunning and destroying the dust shell, a result that places upper limits on the dust-shell size. The optical and infrared observations confirm the radiative heating model and constrain a number of model parameters, including progenitor mass-loss characteristics. All of the SNe in this sample experienced an outburst on the order of tens to hundreds of years prior to the SN explosion followed by periods of less intense mass loss. Although all evidence points to massive progenitors, the variation in the data highlights the diversity in SN IIn progenitor evolution. While these observations do not identify a particular progenitor system, they demonstrate that future, coordinated, multi-wavelength campaigns can constrain theoretical mass-loss models.Comment: 10 pages, 6 figures, accepted to AJ (with comments

    Constraining the Progenitor Companion of the Nearby Type Ia SN 2011fe with a Nebular Spectrum at +981 Days

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    We present an optical nebular spectrum of the nearby Type Ia supernova 2011fe, obtained 981 days after explosion. SN 2011fe exhibits little evolution since the +593 day optical spectrum, but there are several curious aspects in this new extremely late-time regime. We suggest that the persistence of the ∼5800\sim5800~\AA\ feature is due to Na I D, and that a new emission feature at ∼7300\sim7300~\AA\ may be [Ca II]. Also, we discuss whether the new emission feature at ∼6400\sim6400~\AA\ might be [Fe I] or the high-velocity hydrogen predicted by Mazzali et al. The nebular feature at 5200~\AA\ exhibits a linear velocity evolution of ∼350\sim350 km s−1\rm km\ s^{-1} per 100 days from at least +220 to +980 days, but the line's shape also changes in this time, suggesting that line blending contributes to the evolution. At ∼1000\sim 1000 days after explosion, flux from the SN has declined to a point where contribution from a luminous secondary could be detected. In this work we make the first observational tests for a post-impact remnant star and constrain its temperature and luminosity to T≳104T \gtrsim 10^4 K\rm K and L≲104L \lesssim 10^4 L⊙\rm L_{\odot}. Additionally, we do not see any evidence for narrow Hα\alpha emission in our spectrum. We conclude that observations continue to strongly exclude many single-degenerate scenarios for SN 2011fe.Comment: 11 pages, 10 figures, published by MNRA

    History, Quantification, and the Social Sciences

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67009/2/10.1177_000276427702100202.pd
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