734 research outputs found

    Identifying safety strategies for on-farm grain bins using risk analysis

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    The potential for grain bin accidents exists each year on Arkansas farms and farms across the nation. The trend toward increasing utilization of on-farm grain drying and storage could lead to an increase in grain bin accidents. The sharp contrast between a safe, efficient operation and one that leads to injury or death can be represented as sets of farmer-decisions and subsequent chance events. A model was constructed to define the risk associated with grain bin entry and inbin activity so that safety interventions could be identified and implemented to reduce the probability of injury and death. A survey was distributed to Arkansas grain farmers to gather data on the level of safety education, storage techniques, operations management, and other parameters. The data collected from the survey provided quantitative input of many of the model’s probability-distribution functions. Using a fault tree (with parallel modes of failure) in conjunction with a Monte Carlo simulation technique, we evaluated six safety intervention strategies and identified the one with the greatest potential for reducing the risk of serous injury or death. As part of senior design in biological engineering, plans are underway to design and test a probe that can locate and break bridged grain (a common risk factor in grain bin management) while working outside the bin on the ground

    Identifying Concepts and Processes in Mathematics Needed for the Adequate Preparation of Elementary Teachers

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    Days suitable for fieldwork in Missouri (2007)

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    The number of days available to complete land-based agricultural activities influences decisions about inputs (e.g., variety/hybrid planted, pesticide used) and machinery. Limited fieldwork days during critical times, such as tillage, planting and harvest, require careful management. This publication provides information about which days are suitable for fieldwork in Missouri

    Fieldwork days and machinery capacity (2007)

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    One of the more difficult decisions for farm managers is determining the appropriate machinery performance level to match the workload. The vagaries of weather, the narrow window of time to complete critical fieldwork, and the relatively high capital cost of equipment add complexity to an important decision. In this guide, the probability of not completing fieldwork in a timely fashion is used as a way to quantify the risk of incurring excess costs due to weather uncertainty. Without climatic data it is difficult to estimate the extent of risk exposure or to judge whether a farm is over or under capacity

    Days suitable for fieldwork in Missouri (2016)

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    The number of days available to complete land-based agricultural activities influences decisions about inputs, such as variety/hybrid planted and pesticide used, and machinery. The limited fieldwork days available for completing crucial tasks -- such as tillage, planting and harvest -- require careful management

    2000 Philip C. Jessup International Moot Court Competition

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    Pursuant to Article 40(1) of the Statute of the Court, the Republic of Erebus and the Kingdom of Merapi, by a special agreement dated 1 November 2000, have agreed to submit their present dispute concerning maritime boundary delimitation and the seabed mining facility to the jurisdiction of the International Court of Justice under Article 36(1) of the Statute of the Court

    Physicochemical Properties and Catalytic Behavior of the Molecular Sieve SSZ-70

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    SSZ-70 is synthesized using 1,3-bis(isobutyl)imidazolium, 1,3-bis(cyclohexyl)imidazolium, and 1,3-bis(cycloheptyl)imidazolium structure directing agents (SDAs), and the solids obtained are characterized by powder X-ray diffraction (XRD), ^(29)Si magic angle spinning nuclear magnetic resonance (MAS NMR), electron microscopy, nitrogen and hydrocarbon adsorption, and thermogravimetric analyses. The physicochemical properties of SSZ-70 show that it is a new molecular sieve that has similarities to MWW-type materials. The catalytic behavior of SSZ-70 is evaluated through the use of the constraint index (CI) test. Distinct differences in the reactivity between Al-SSZ-70 and SSZ-25 (MWW) are observed and are the consequences of the structural differences between these two molecular sieves

    Debris disks as signposts of terrestrial planet formation. II Dependence of exoplanet architectures on giant planet and disk properties

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    We present models for the formation of terrestrial planets, and the collisional evolution of debris disks, in planetary systems that contain multiple unstable gas giants. We previously showed that the dynamics of the giant planets introduces a correlation between the presence of terrestrial planets and debris disks. Here we present new simulations that show that this connection is qualitatively robust to changes in: the mass distribution of the giant planets, the width and mass distribution of the outer planetesimal disk, and the presence of gas in the disk. We discuss how variations in these parameters affect the evolution. Systems with equal-mass giant planets undergo the most violent instabilities, and these destroy both terrestrial planets and the outer planetesimal disks that produce debris disks. In contrast, systems with low-mass giant planets efficiently produce both terrestrial planets and debris disks. A large fraction of systems with low-mass outermost giant planets have stable gaps between these planets that are frequently populated by planetesimals. Planetesimal belts between outer giant planets may affect debris disk SEDs. If Earth-mass seeds are present in outer planetesimal disks, the disks radially spread to colder temperatures. We argue that this may explain the very low frequency of > 1 Gyr-old solar-type stars with observed 24 micron excesses. Among the (limited) set of configurations explored, the best candidates for hosting terrestrial planets at ~1 AU are stars older than 0.1-1 Gyr with bright debris disks at 70 micron but with no currently-known giant planets. These systems combine evidence for rocky building blocks, with giant planet properties least likely to undergo destructive dynamical evolution. We predict an anti-correlation between debris disks and eccentric giant planets, and a positive correlation between debris disks and terrestrial planets.Comment: Astronomy and Astrophysics, in press. Movies from simulations are at http://www.obs.u-bordeaux1.fr/e3arths/raymond/movies_debris.htm

    CLEAR II: Evidence for Early Formation of the Most Compact Quiescent Galaxies at High Redshift

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    The origin of the correlations between mass, morphology, quenched fraction, and formation history in galaxies is difficult to define, primarily due to the uncertainties in galaxy star-formation histories. Star-formation histories are better constrained for higher redshift galaxies, observed closer to their formation and quenching epochs. Here we use "non-parametric" star-formation histories and a nested sampling method to derive constraints on the formation and quenching timescales of quiescent galaxies at 0.7<z<2.50.7<z<2.5. We model deep HST grism spectroscopy and photometry from the CLEAR (CANDELS Lymanα-\alpha Emission at Reionization) survey. The galaxy formation redshifts, z50z_{50} (defined as the point where they had formed 50\% of their stellar mass) range from z502z_{50}\sim 2 (shortly prior to the observed epoch) up to z5058z_{50} \simeq 5-8. \editone{We find that early formation redshifts are correlated with high stellar-mass surface densities, logΣ1/(M kpc2)>\log \Sigma_1 / (M_\odot\ \mathrm{kpc}^{-2}) >10.25, where Σ1\Sigma_1 is the stellar mass within 1~pkpc (proper kpc). Quiescent galaxies with the highest stellar-mass surface density, logΣ1/(M kpc2)>10.25\log\Sigma_1 / (M_\odot\ \mathrm{kpc}^{-2}) > 10.25, } show a \textit{minimum} formation redshift: all such objects in our sample have z50>2.9z_{50} > 2.9. Quiescent galaxies with lower surface density, $\log \Sigma_1 / (M_\odot\ \mathrm{kpc}^{-2}) = 9.5 - 10.25,showarangeofformationepochs(, show a range of formation epochs (z_{50} \simeq 1.5 - 8),implyingthesegalaxiesexperiencedarangeofformationandassemblyhistories.Wearguethatthesurfacedensitythreshold), implying these galaxies experienced a range of formation and assembly histories. We argue that the surface density threshold \log\Sigma_1/(M_\odot\ \mathrm{kpc}^{-2})>10.25$ uniquely identifies galaxies that formed in the first few Gyr after the Big Bang, and we discuss the implications this has for galaxy formation models.Comment: 13 pages, 7 figures, accepted for publication in ApJ. Includes an interactive online appendix (https://vince-ec.github.io/appendix/appendix
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