316 research outputs found

    Functional quality management systems for livestock producers

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    Quality management systems programs were used to help farmers (niche market producers, a Midwest cooperative of pork producers, and other livestock producers) improve their management techniques and cost-control skills and increase market access

    Distance measures in gravitational-wave astrophysics and cosmology

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    We present quantities which characterize the sensitivity of gravitational-wave observatories to sources at cosmological distances. In particular, we introduce and generalize the horizon, range, response, and reach distances. These quantities incorporate a number of important effects, including cosmologically well-defined distances and volumes, cosmological redshift, cosmological time dilation, and rate density evolution. In addition, these quantities incorporate unique aspects of gravitational wave detectors, such as the variable sky sensitivity of the detectors and the scaling of the sensitivity with inverse distance. An online calculator (https://users.rcc.uchicago.edu/~dholz/gwc/) and python notebook (https://github.com/hsinyuc/distancetool) to determine GW distances are available. We provide answers to the question: "How far can gravitational-wave detectors hear?

    Gas phase absorption of C702+ below 10 K: astronomical implications

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    The electronic spectrum of the fullerene dication C702+ has been measured in the gas phase at low temperature in a cryogenic radiofrequency ion trap. The spectrum consists of a strong origin band at 7030 Å and two weaker features to higher energy. The bands have FWHMs of 35 Å indicating an excited state lifetime on the order of one-tenth of a picosecond. Absorption cross-section measurements yield (2 ± 1) × 10−15 cm2 at 7030 Å. These results are used to predict the depth of diffuse interstellar bands (DIBs) due to the absorption by C702+. At an assumed column density of 2 × 1012 cm−2 the attenuation of starlight at 7030 Å is around 0.4% and thus the detection of such a shallow and broad interstellar band would be difficult. The electronic spectrum of C602+ shows no absorptions in the visible. Below 4000 Å the spectra of C60, C60+ and C602+ are similar. The large intrinsic FWHM of the features in this region, ~200 Å for the band near 3250 Å, make them unsuitable for DIB detection

    Investigation of Strategic Partnership Opportunities with Iowa Convenience Store Retailers

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    This is a final report of a project funded by the Regional Food Systems Working Group. Investigators surveyed buyers representing 108 of the 180 convenience stores in the Des Moines urban area and a corresponding rural area of Iowa about the opportunitites for Iowa producers to market local products, primarily fresh fruit and vegetables.https://lib.dr.iastate.edu/extension_pubs/1058/thumbnail.jp

    Synthesis, Molecular Structure, and Reactivity of Dinuclear Copper(II) Complexes with Carboxylate-Rich Coordination Environments

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    The dinucleating ligand N,N‘-(2-hydroxy-5-methyl-1,3-xylylene)bis(N-(carboxymethyl)glycine) (CH3HXTA) has been used to synthesize the dinuclear Cu(II) bis(pyridine) complex Na[Cu2(CH3HXTA)(Py)2]·1.5(1,4-dioxane) (Na(1)):  triclinic space group P1̄ (a = 12.550(3) Å, b = 13.413(3) Å, c = 13.540(4) Å, α = 117.12(2)°, β = 104.70 (2)°, and γ = 92.13(2)°). The structure shows two distinct distorted square pyramidal Cu(II) centers with each Cu(II) ion bound by two carboxylate oxygen atoms, one amine nitrogen atom, a phenolate oxygen atom, and one pyridine nitrogen atom. The Cu--Cu separation is 3.531 Å, and the Cu1−O1−Cu2 angle is 123.7°. The phenyl ring of the CH3HXTA ligand is twisted relative to the Cu1−O1−Cu2 plane, and the resulting dihedral angle is 44.2°. The electronic absorption spectrum of 1 in aqueous solution at pH 3 suggests a shift toward trigonal bipyramidal Cu(II) coordination in solution. Spectral titration of Na[Cu2(CH3HXTA)(H2O)2] with L (where L = pyridine or sodium cyanide) results in complexes with terminal L groups. These exogenous ligands appear to bind in a positive cooperative stepwise fashion. Variable-temperature magnetic susceptibility data for 1 indicate that the Cu(II) ions are antiferromagnetically coupled (−2J = 168 cm-1). X-band EPR spectra of an aqueous solution of 1 shows isotropic signals with g = 2.14, while a powdered sample of 1 provides no EPR spectrum. A ΔMs = 2 transition at g = ∼4.5, expected for weakly magnetically coupled Cu(II) ions, is not observed for powdered samples but is observed for a methanolic solution sample of 1. On the basis of these data, the two Cu(II) ions are antiferromagnetically coupled in the solid state but due to a coordination geometry change become weakly ferromagnetically or antiferromagnetically coupled in solution. 1H NMR studies on a methanol solution of 1 are consistent with weak spin-coupling in solution

    Retro-MACHOs: Pi in the sky?

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    Shine a flashlight on a black hole, and one is greeted with the return of a series of concentric rings of light. For a point source of light, and for perfect alignment of the lens, source, and observer, the rings are of infinite brightness (in the limit of geometric optics). In this manner, distant black holes can be revealed through their reflection of light from the Sun. Such retro-MACHO events involve photons leaving the Sun, making a Pi rotation about the black hole, and then returning to be detected at the Earth. Our calculations show that, although the light return is quite small, it may nonetheless be detectable for stellar-mass black holes at the edge of our solar system. For example, all (unobscured) black holes of mass M or greater will be observable to a limiting magnitude m, at a distance given by: 0.02 pc x \sqrt[3]{10^{(m-30)/2.5} (M/10 M_sun)^2}. Discovery of a Retro-MACHO offers a way to directly image the presence of a black hole, and would be a stunning confirmation of strong-field general relativity.Comment: 5 pages, 3 figures. ApJ in pres

    Apparent horizons in simplicial Brill wave initial data

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    We construct initial data for a particular class of Brill wave metrics using Regge calculus, and compare the results to a corresponding continuum solution, finding excellent agreement. We then search for trapped surfaces in both sets of initial data, and provide an independent verification of the existence of an apparent horizon once a critical gravitational wave amplitude is passed. Our estimate of this critical value, using both the Regge and continuum solutions, supports other recent findings.Comment: 7 pages, 6 EPS figures, LaTeX 2e. Submitted to Class. Quant. Gra

    Ratcheting ambition to limit warming to 1.5 °C–trade-offs between emission reductions and carbon dioxide removal

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    Mitigation scenarios to limit global warming to 1.5 °C or less in 2100 often rely on large amounts of carbon dioxide removal (CDR), which carry significant potential social, environmental, political and economic risks. A precautionary approach to scenario creation is therefore indicated. This letter presents the results of such a precautionary modelling exercise in which the models C-ROADS and En-ROADS were used to generate a series of 1.5 °C mitigation scenarios that apply increasingly stringent constraints on the scale and type of CDR available. This allows us to explore the trade-offs between near-term stringency of emission reductions and assumptions about future availability of CDR. In particular, we find that regardless of CDR assumptions, near-term ambition increase ('ratcheting') is required for any 1.5 °C pathway, making this letter timely for the facilitative, or Talanoa, dialogue to be conducted by the UNFCCC in 2018. By highlighting the difference between net and gross reduction rates, often obscured in scenarios, we find that mid-term gross CO2emission reduction rates in scenarios with CDR constraints increase to levels without historical precedence. This in turn highlights, in addition to the need to substantially increase CO2reduction rates, the need to improve emission reductions for non-CO2greenhouse gases. Further, scenarios in which all or part of the CDR is implemented as non-permanent storage exhibit storage loss emissions, which partly offset CDR, highlighting the importance of differentiating between net and gross CDR in scenarios. We find in some scenarios storage loss trending to similar values as gross CDR, indicating that gross CDR would have to be maintained simply to offset the storage losses of CO2sequestered earlier, without any additional net climate benefit

    Hydrostatic Expansion and Spin Changes During Type I X-Ray Bursts

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    We present calculations of the spin-down of a neutron star atmosphere due to hydrostatic expansion during a Type I X-ray burst. We show that (i) Cumming and Bildsten overestimated the spin-down of rigidly-rotating atmospheres by a factor of two, and (ii) general relativity has a small (5-10%) effect on the angular momentum conservation law. We rescale our results to different neutron star masses, rotation rates and equations of state, and present some detailed rotational profiles. Comparing with recent observations of large frequency shifts in MXB 1658-298 and 4U 1916-053, we find that the spin-down expected if the atmosphere rotates rigidly is a factor of two to three less than the observed values. If differential rotation is allowed to persist, we find that the upper layers of the atmosphere spin down by an amount comparable to the observed values; however, there is no compelling reason to expect the observed spin frequency to be that of only the outermost layers. We conclude that hydrostatic expansion and angular momentum conservation alone cannot account for the largest frequency shifts observed during Type I bursts.Comment: Submitted to the Astrophysical Journal (13 pages, including 4 figures

    Agricultural Phosphorus Management and Water Quality Protection in the Midwest

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    For nutrient management planners -- to understand the risk of phosphorus in surface waters and to manage this risk. Targeted for Iowa, Kansas, Missouri, and Nebraska.https://lib.dr.iastate.edu/extension_ag_pubs/1151/thumbnail.jp
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