8,081 research outputs found

    The design and testing of a memory metal actuated boom release mechanism

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    A boom latch and release mechanism was designed, manufactured and tested, based on a specification for the ISEE-B satellite mechanism. From experimental results obtained, it is possible to calculate the energy available and the operating torques which can be achieved from a torsional shape memory element in terms of the reversible strain induced by prior working. Some guidelines to be followed when designing mechanisms actuated by shape memory elements are included

    Simulating a White Dwarf-dominated Galactic Halo

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    Observational evidence has suggested the possibility of a Galactic halo which is dominated by white dwarfs (WDs). While debate continues concerning the interpretation of this evidence, it is clear that an initial mass function (IMF) biased heavily toward WD precursors (1 < m/Msol < 8), at least in the early Universe, would be necessary in generating such a halo. Within the framework of homogeneous, closed-box models of Galaxy formation, such biased IMFs lead to an unavoidable overproduction of carbon and nitrogen relative to oxygen (as measured against the abundance patterns in the oldest stars of the Milky Way). Using a three-dimensional Tree N-body smoothed particle hydrodynamics code, we study the dynamics and chemical evolution of a galaxy with different IMFs. Both invariant and metallicity-dependent IMFs are considered. Our variable IMF model invokes a WD-precursor-dominated IMF for metallicities less than 5% solar (primarily the Galactic halo), and the canonical Salpeter IMF otherwise (primarily the disk). Halo WD density distributions and C,N/O abundance patterns are presented. While Galactic haloes comprised of ~5% (by mass) of WDs are not supported by our simulations, mass fractions of ~1-2% cannot be ruled out. This conclusion is consistent with the present-day observational constraints.Comment: accepted for publication in MNRA

    Analysis of charm pair production at the LHC

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    The DGLAP and CCFM approaches to perturbative QCD evolution have been investigated by examining correlations of charmed hadron pairs in pp collisions at √ s = 7 TeV. The theoretical models are compared to the data taken by the LHCb experiment. Differences in the parton kinematics between the two approaches are discussed. In general a model incorporating NLO diagrams matched to parton showers describes the data best

    A Comparison of Risk Exposure in Aquaculture and Agricultural Businesses

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    Agriculture and aquaculture have common features associated with their biological nature affecting risk exposure of the businesses. The aim of this paper is to compare risk exposure in salmon farming and agricultural enterprises in Norway by using an implicit error component model to examine the risk structure of yields, prices and economic returns at the farm level. Results indicate a higher farm-level year-to-year variability in yields, prices and economic returns in salmon farming than in agricultural enterprises. The variability in livestock enterprises was generally lower than for crop enterprises. Return on assets was highest in salmon farming with an average annual return of 9.2%. All of the agricultural farm types exhibited a negative average return on assets on average. Stochastic dominance tests of the distribution of economic returns from aquaculture and agricultural farm types showed salmon farming to be the most risk efficient alternative and salmon farming was most attractive from an investor’s perspective.Risk analysis, variability, Norway, Risk and Uncertainty,

    Volcanic smog and cardiometabolic health: Hawaiian hypertension?

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    Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149349/1/jch13500.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149349/2/jch13500_am.pd

    Turning corn silage analysis into economic value for the beef industry

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    Master of AgribusinessDepartment of Agricultural EconomicsElizabeth YeagerThe corn silage market is typically focused heavily on the dairy market and results for corn silage plots are dedicated to the dairy industry specifically to get to the overall answer of Milk/Acre.Thebeefcattleindustryismoreinterestedinpoundsofbeefthatcanbegainedfromcornsilage.Thereareroughly6.2millionacresofcornsilageintheUS.Withinthat6millionacres,roughlyhalfisfedtobeefcattle,butthecornsilageindustryhasnotfocusedonthisaspectofthemarket.WithinMycogenSeedstherehasbeenaneverincreasingdemandtofindawaytodeliverthecornsilageplotdatainauseableformatforbeefproducers.Bydeliveringcornsilageplotdatatobeefproducers,Mycogenhasaspirationsofincreasingit’smarketshareofthecornsilagemarketinKansasaswellasacrosstheUS,whileatthesametimeincreasingtheawarenessofhowqualityofacornsilagehybridcanaffectaproducersoperation.Thisthesisexaminescornsilageplotinfosampleanalysisandspecificfeedanalysiscalculations.Withthesespecificcalculations,thecornsilageplotwillillustrateinformationinaformthatbeefproducerswillunderstand, Milk/Acre. The beef cattle industry is more interested in pounds of beef that can be gained from corn silage. There are roughly 6.2 million acres of corn silage in the US. Within that 6 million acres, roughly half is fed to beef cattle, but the corn silage industry has not focused on this aspect of the market. Within Mycogen Seeds there has been an ever increasing demand to find a way to deliver the corn silage plot data in a useable format for beef producers. By delivering corn silage plot data to beef producers, Mycogen has aspirations of increasing it’s market share of the corn silage market in Kansas as well as across the US, while at the same time increasing the awareness of how quality of a corn silage hybrid can affect a producers operation. This thesis examines corn silage plot info sample analysis and specific feed analysis calculations. With these specific calculations, the corn silage plot will illustrate information in a form that beef producers will understand, Beef Produced/Acre. At the same time, this thesis will examine the industry wide concept that tonnage is the only component that is important when selecting a corn silage hybrid. Finally this thesis will examine at what point ($/bushel) in the corn grain market does it make sense to start looking at utilizing corn silage over dry rolled corn by comparing price per MegaCalorie of energy by utilizing 25 year historical corn grain prices and using the Purdue Method of determining the cost of corn silage on a per ton basis

    Fire impacts recruitment more than survival of small-mammals in a tropical savanna

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    The frequency and spatial patterning of fire for optimal biodiversity conservation is often poorly understood by managers, in part due to a lack of understanding of the mechanisms responsible for altering population dynamics of individual species. We investigated changes in the vital rates (survival and recruitment) of four small mammal species (three marsupials and one rodent) in a tropical savanna under four different experimental fire treatments applied at a landscape scale. Apparent survival declined in all fire treatments for only one of four small mammal species (northern brown bandicoot Isoodon macrourus). Recruitment was reduced in three of four species in multiple fire treatments. The suppression of recruitment in the northern brown bandicoot and the brushtail possum Trichosurus vulpecula populations was greatest immediately after the initial fire treatment was applied, compared to remaining treatment applications in successive years, possibly due to an elevated fire intensity as a result of higher initial fuel loads. The results suggest that higher intensity fire impacted recruitment more than survival for small mammals at this site. To assist fire managers to conserve small mammal populations in tropical savannas, we recommend fire regimes that optimise habitat resources for recruitment. This may be achieved by a reduction in fire frequency and managing fuel loads to prevent an increase in fire intensity

    Arm Position During Ambulatory Blood Pressure Monitoring: A Review of the Evidence and Clinical Guidelines

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106696/1/jch12255.pd
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