2,368 research outputs found

    The Effect of the Housing Boom on Farm Land Values via Tax-Deferred Exchanges

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    This project examines Section 1031 of the Internal Revenue Code and agriculture land exchanges. Stakeholders in rural communities and agriculture are particularly interested in Section 1031 because the recent growth in transaction values of farmland may have, in part, been stimulated by Section 1031 land exchanges. Further, although many have speculated that such exchanges are widely used, little empirical research exists about the provision. We examine the theory of exchanges and develop a theoretical premium value for exchanges. We also present the first evidence of like-kind exchanges involving farmland using Federal tax data.Like-Kind Exchange, Capital Gains Tax, Agricultural Land, Land Economics/Use, Public Economics, Q15, H24,

    Bleomycin increases neutrophil adhesion to human vascular endothelial cells independently of upregulation of ICAM-1 and E-selectin

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    © 2016 Taylor & Francis. Aim of the Study: Bleomycin-induced lung disease is a serious complication of therapy characterized by alveolar injury, cytokine release, inflammatory cell recruitment, and eventually pulmonary fibrosis. The mechanisms underlying bleomycin-induced pulmonary fibrosis may be relevant to other progressive scarring diseases of the lungs. Pulmonary vascular endothelial cells are critically involved in immune cell extravasation at sites of injury through adhesion molecule expression and cytokine release. We sought to determine the effects of bleomycin on adhesion molecule expression and cytokine release by pulmonary vascular endothelial cells, and their functional relevance to inflammatory cell recruitment. Materials and Methods: The effects of pharmacologically relevant concentrations of bleomycin on adhesion molecule expression and cytokine release by human vascular endothelial cells in vitro were studied by flow cytometry, quantitative polymerase chain reaction, and enzyme-linked immunosorbent assay. A flow chamber model was used to assess the functional consequences on adhesion of flowing human neutrophils to endothelial cell monolayers. Results: Bleomycin increased intercellular adhesion molecule 1 (ICAM-1; CD54), vascular cell adhesion molecule (VCAM-1; CD106), and E-selectin (CD62E) expression, and increased monocyte chemoattractant protein (MCP-1) and interleukin (IL-8) release by endothelial cells. Increases in protein expression were accompanied by increased mRNA transcription. In contrast, there was no direct effect of bleomycin on the profibrotic cytokines transforming growth factor-beta (TGF-β), platelet-derived growth factor-BB (PDGF-BB), or endothelin-1. Under flow conditions, endothelial cells exposed to bleomycin supported increased neutrophil adhesion which was independent of ICAM-1 or E-selectin. Conclusion: Our findings demonstrate that bleomycin promotes endothelial-mediated inflammation and neutrophil adhesion. These mechanisms may contribute to the development of pulmonary fibrosis by supporting immune cell recruitment in the lungs

    A connectivity portfolio effect stabilizes marine reserve performance

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    Well-managed and enforced no-take marine reserves generate important larval subsidies to neighboring habitats and thereby con-tribute to the long-term sustainability of fisheries. However, larval dispersal patterns are variable, which leads to temporal fluctua-tions in the contribution of a single reserve to the replenishment of local populations. Identifying management strategies that mit-igate the uncertainty in larval supply will help ensure the stability of recruitment dynamics and minimize the volatility in fishery catches. Here, we use genetic parentage analysis to show extreme variability in both the dispersal patterns and recruitment contribu-tion of four individual marine reserves across six discrete recruit-ment cohorts for coral grouper (Plectropomus maculatus) on the Great Barrier Reef. Together, however, the asynchronous contri-butions from multiple reserves create temporal stability in recruit-ment via a connectivity portfolio effect. This dampening effect reduces the variability in larval supply from individual reserves by a factor of 1.8, which effectively halves the uncertainty in the recruitment contribution of individual reserves. Thus, not only does the network of four marine reserves generate valuable larval subsidies to neighboring habitats, the aggregate effect of individual reserves mitigates temporal fluctuations in dispersal patterns and the replenishment of local populations. Our results indicate that small networks of marine reserves yield previously unrecog-nized stabilizing benefits that ensure a consistent larval supply to replenish exploited fish stocks

    The complex network of global cargo ship movements

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    Transportation networks play a crucial role in human mobility, the exchange of goods, and the spread of invasive species. With 90% of world trade carried by sea, the global network of merchant ships provides one of the most important modes of transportation. Here we use information about the itineraries of 16,363 cargo ships during the year 2007 to construct a network of links between ports. We show that the network has several features which set it apart from other transportation networks. In particular, most ships can be classified in three categories: bulk dry carriers, container ships and oil tankers. These three categories do not only differ in the ships' physical characteristics, but also in their mobility patterns and networks. Container ships follow regularly repeating paths whereas bulk dry carriers and oil tankers move less predictably between ports. The network of all ship movements possesses a heavy-tailed distribution for the connectivity of ports and for the loads transported on the links with systematic differences between ship types. The data analyzed in this paper improve current assumptions based on gravity models of ship movements, an important step towards understanding patterns of global trade and bioinvasion.Comment: 7 figures Accepted for publication by Journal of the Royal Society Interface (2010) For supplementary information, see http://www.icbm.de/~blasius/publications.htm

    Planetary systems around close binary stars: the case of the very dusty, Sun-like, spectroscopic binary BD+20 307

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    Field star BD+20 307 is the dustiest known main sequence star, based on the fraction of its bolometric luminosity, 4%, that is emitted at infrared wavelengths. The particles that carry this large IR luminosity are unusually warm, comparable to the temperature of the zodiacal dust in the solar system, and their existence is likely to be a consequence of a fairly recent collision of large objects such as planets or planetary embryos. Thus, the age of BD+20 307 is potentially of interest in constraining the era of terrestrial planet formation. The present project was initiated with an attempt to derive this age using the Chandra X-ray Observatory to measure the X-ray flux of BD+20 307 in conjunction with extensive photometric and spectroscopic monitoring observations from Fairborn Observatory. However, the recent realization that BD+20 307 is a short period, double-line, spectroscopic binary whose components have very different lithium abundances, vitiates standard methods of age determination. We find the system to be metal-poor; this, combined with its measured lithium abundances, indicates that BD+20 307 may be several to many Gyr old. BD+20 307 affords astronomy a rare peek into a mature planetary system in orbit around a close binary star (because such systems are not amenable to study by the precision radial velocity technique).Comment: accepted for ApJ, December 10, 200

    Towards the Anomalous Dimension to Order Lambda_QCD/m_b for Phase Space Restricted B --> X(u) ell anti-nu and B --> X(s) gamma

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    We examine the anomalous dimension matrix appropriate for the phase space restricted B --> X(u) ell anti-nu and B --> X(s) gamma decay spectra to subleading nonperturbative order. The effects of the time ordered products of the HQET Lagrangian with the leading order shape function operator are calculated, as are the anomalous dimensions of subleading operators. We establish the renormalizability and closure of a subset of the non-local operator basis, a requirement for the establishment of factorization theorems at this order. Operator mixing is found between the operators which occur to subleading order, requiring the subleading operator basis be extended. We comment on the requirement for new shape functions to be introduced to characterize the matrix elements of these new operators, and the phenomenological consequences for extractions of Vub|V_{ub}|.Comment: 23 pages, 3 figures V2- Minor Typos Fixe

    Direct numerical simulation of “fountain filling box” flow with a confined weak laminar plane fountain

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    A “fountain filling box” flow produced by discharging a weak laminar plane fountain in a confined open channel is studied numerically. Two-dimensional direct numerical simulations were performed for weak plane fountains. The development of the fountain flow experiences five stages; the initial upflow and the subsequent downflow after the fountain penetrates to the maximum height, followed by the outward movement of the intrusion of the fallen fountain fluid on the channel bottom, and then the wall fountain formed by the impingement of the intrusion on the vertical sidewall, which results in the reversed flow, and finally the gradual stratification of the fluid. The behavior of the intrusion can be approximately described with the plane gravity current theory. The period for the intrusion to reach the bounded side wall increases with increasing Re or decreasing Fr. Three regimes are found for the wall fountain behavior; “no-falling,” “slumping down,” and “rolling down” behavior. Convection, mixing, conduction, and filling all contribute to the formation and development of stratification, but their effects vary at different stages. For the initial stages, convection and mixing play a key role, resulting in an increasing bulk entrainment rate, while conduction and filling are dominant after quasi-steady stratification is created, presenting a decreasing bulk entrainment rate

    A Precise Water Abundance Measurement for the Hot Jupiter WASP-43b

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    The water abundance in a planetary atmosphere provides a key constraint on the planet's primordial origins because water ice is expected to play an important role in the core accretion model of planet formation. However, the water content of the Solar System giant planets is not well known because water is sequestered in clouds deep in their atmospheres. By contrast, short-period exoplanets have such high temperatures that their atmospheres have water in the gas phase, making it possible to measure the water abundance for these objects. We present a precise determination of the water abundance in the atmosphere of the 2 MJupM_\mathrm{Jup} short-period exoplanet WASP-43b based on thermal emission and transmission spectroscopy measurements obtained with the Hubble Space Telescope. We find the water content is consistent with the value expected in a solar composition gas at planetary temperatures (0.4-3.5x solar at 1 σ\sigma confidence). The metallicity of WASP-43b's atmosphere suggested by this result extends the trend observed in the Solar System of lower metal enrichment for higher planet masses.Comment: Accepted to ApJL; this version contains three supplemental figures that are not included in the published paper. See also our companion paper "Thermal structure of an exoplanet atmosphere from phase-resolved emission spectroscopy" by Stevenson et a
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