2,608 research outputs found

    Investigation of Part Accuracy and Surface Roughness in Rapid Freeze Prototyping Based Investment Casting

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    The study as described in this paper is aimed at investigating the dimensional accuracy and surface finish of metal parts made by investment casting with ice patterns generated by rapid freeze prototyping. The process of investment casting with ice patterns is described and contrast with conventional investment casting with wax patterns is made. The selection of binder material for ceramic slurries and the need for an interface agent to separate the ice pattern from the ceramic slurry in the mold making process are discussed. The accuracy and surface finish of ice patterns and of the metal castings are presented and discussed. The parts used in this investigation include cylinders with vertical and slant walls and a turbine impeller.The authors gratefully acknowledge the financial support from the National Science Foundation grants (DMI-0128313 and DMI-0140625) and the Research Board of University of Missouri at Rolla.Mechanical Engineerin

    Factors Affecting Pregnancy in Free-ranging Elk, Cervus elaphus nelsoni, in Michigan

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    Uncertainty exists as to which factors are most closely related to probability of pregnancy in Elk (Cervus elaphus), which thresholds are key for managers who want to assess the potential productivity of free-ranging Elk herds, and whether these thresholds vary among populations. We examined relationships among pregnancy, age, and mass for 513 harvested free-ranging Elk in Michigan, and compared relationships with other published models and with thresholds derived from other free-ranging and penned populations to see if relationships were consistent among populations. Pregnancy rates varied (chi22 = 136.3; P < 0.0001) among yearling (0.30), prime-aged (2.5-11.5-year-olds; 0.88), and old (> 12.5-year-olds; 0.60) cows. Probability of pregnancy in adult cows was related to mass (chi2 = 7.4; P = 0.006), age (chi2 = 12.6; P = 0.0004) and age class (chi2 = 16.4; P < 0.0001), but not to lactation status (chi2 = 0.4; P = 0.515); pregnancy was also positively related (chi2 = 15.8; P < 0.0001) to mass in yearlings. Probability of pregnancy increased 1.02× and 1.04× for each 1 kg increase in body mass of adult and yearling cows, respectively, and prime-aged cows were 4.9× more likely to conceive than old cows. Compared to thresholds derived primarily from penned or farmed Elk, both adult and yearling free-ranging Elk in Michigan and elsewhere were able to achieve higher levels of pregnancy at lower body mass. Thresholds also varied among free-ranging Elk populations. Given variation among populations, managers should calibrate mass-pregnancy relationships for their respective populations to determine whether condition is potentially limiting pregnancy in their populations

    Management of bovine tuberculosis in Michigan wildlife: Current status and near term prospects

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    Surveillance and control activities for bovine tuberculosis (bTB) in free-ranging Michigan white-tailed deer (Odocoileus virginianus) have now been underway for over a decade. Significant progress has been made, lowering apparent prevalence in deer in the core area by >60%, primarily via reduction of deer densities through hunting, and restrictions on public feeding and baiting of deer. These broad strategies of the Michigan Department of Natural Resources (MDNR), implemented with the cooperation of Michigan deer hunters, halved the deer population in the bTB endemic area. However, as hunters see fewer deer, their willingness to sustain aggressive harvests has waned, and public resentment of control measures has grown. During the past four years, apparent prevalence in core area deer has held approximately steady just below 2%. After bottoming out in 2004 at an estimated 10–12 deer/km2, deer numbers have since rebounded by ∼30%. Public compliance with baiting and feeding restrictions has been variable. In general, hunters in the core area do not perceive bTB as a problem, in spite of 13 years of MDNR outreach. To date, MDNR has expended more than US23milliononTB−relatedactivities.Oflate,asubstantialportionofthatfundinghasbeendivertedtosupportotherprogramswhichhavesufferedfrombudgetshortfalls.Livestockherdbreakdownscontinuetooccursporadically,averaging3–4peryear2005topresent.Intotal,46cattleand4captivedeerherdshavebeendiagnosedbTBpositivestatewide,themajorityyieldingonly1positiveanimal.Fivecattleherdsweretwiceinfected,onethrice.MichiganDepartmentofAgriculture(MDA)policyemphasishasshiftedtowardsobtainingproducersupportforwildliferiskmitigationandfarmbiosecurity.Fundinghasprovenalimitingfactor,withthemajorityoftheUS23 million on TB-related activities. Of late, a substantial portion of that funding has been diverted to support other programs which have suffered from budget shortfalls. Livestock herd breakdowns continue to occur sporadically, averaging 3–4 per year 2005 to present. In total, 46 cattle and 4 captive deer herds have been diagnosed bTB positive statewide, the majority yielding only 1 positive animal. Five cattle herds were twice infected, one thrice. Michigan Department of Agriculture (MDA) policy emphasis has shifted towards obtaining producer support for wildlife risk mitigation and farm biosecurity. Funding has proven a limiting factor, with the majority of the US63 million spent to date devoted to whole herd testing. Nevertheless, some initiatives justify cautious optimism. Promising research to support eventual vaccination of wild deer continues. Some hunters and landowners have begun to recognize the costs of high deer densities and supplemental feeding. A peninsula-wide ban on baiting and feeding was enacted. Some cattle producers, recognizing their precarious circumstances, have begun work to change long-held prevailing opinions among their peers about farm biosecurity. Yet formidable challenges remain, and evidence suggests that eradication of bTB, if it can be achieved, will take decades, and will require greater public and political resolve than has been demonstrated thus far

    Adaptation strategies and approaches for forested watersheds

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    Intentional climate adaptation planning for ecosystems has become a necessary part of the job for natural resource managers and natural resource professionals in this era of non-stationarity. One of the major challenges in adapting ecosystems to climate change is in the translation of broad adaptation concepts to specific, tangible actions. Addressing management goals and values while considering the long-term risks associated with local climate change can make forested watershed management plans more robust to uncertainty and changing conditions. We provide a menu of tiered adaptation strategies, which we developed with a focus on forests of the Midwest and Northeastern U.S., as part of a flexible framework to support the integration of climate change considerations into forested watershed management and conservation activities. This menu encapsulates ideas from the literature into statements that signify climate adaptation intention and provide examples of associated tactics to help ground the concepts in specific actions. Finally, we describe two demonstration projects, shared through the Northern Institute of Applied Climate Science’s Climate Change Response Framework, that have used this Forested Watershed Adaptation Menu and Adaptation Workbook in project-level planning

    \u3ci\u3eMycobacterium bovis \u3c/i\u3ein Coyotes from Michigan

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    During a survey for tuberculosis in wild carnivores and omnivores, Mycobacteriurn bovis was cultured from pooled lymph nodes of three adult female coyotes (Canis latrans) harvested by hunters in Michigan (USA). No gross or histologic lesions suggestive of tuberculosis were seen in these animals. One coyote was taken from Montmorency county and two coyotes from Alcona county located in the northeastern portion of Michigan’s Lower Peninsula where free-ranging white-tailed deer (Odocoileus virginianus) have been found infected with bovine tuberculosis. It is thought that these coyotes became infected with M. bovis through the consumption of tuberculous deer. Other species included in the survey were the opossum (Didelphis virginiana), raccoon (Procyon lotor), red fox (Vulpes vulpes), bobcat (Felis rufus), and badger (Taxidea taxus)

    Salinity and temperature balances at the SPURS central mooring during fall and winter

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    Author Posting. © The Oceanography Society, 2015. This article is posted here by permission of The Oceanography Society for personal use, not for redistribution. The definitive version was published in Oceanography 28, no. 1 (2015): 56-65, doi:10.5670/oceanog.2015.06.One part of the Salinity Processes in the Upper-ocean Regional Study (SPURS) field campaign focused on understanding the physical processes affecting the evolution of upper-ocean salinity in the region of climatological maximum sea surface salinity in the subtropical North Atlantic (SPURS-1). An upper-ocean salinity budget provides a useful framework for increasing this understanding. The SPURS-1 program included a central heavily instrumented mooring for making accurate measurements of air-sea surface fluxes, as well as other moorings, Argo floats, and gliders that together formed a dense observational array. Data from this array are used to estimate terms in the upper-ocean salinity and heat budgets during the SPURS-1 campaign, with a focus on the first several months (October 2012 to February 2013) when the surface mixed layer was becoming deeper, fresher, and cooler. Specifically, we examine the salinity and temperature balances for an upper-ocean mixed layer, defined as the layer where the density is within 0.4 kg m–3 of its surface value. The gross features of the evolution of upper-ocean salinity and temperature during this fall/winter season are explained by a combination of evaporation and precipitation at the sea surface, horizontal transport of heat and salt by mixed-layer currents, and vertical entrainment of fresher, cooler fluid into the layer as it deepened. While all of these processes were important in the observed seasonal (fall) freshening at this location in the salinity-maximum region, the variability of salinity on monthly-to-intraseasonal time scales resulted primarily from horizontal advection.J.T. Farrar, A.J. Plueddemann, J.B. Edson, and the deployment of the central mooring were supported by NASA grant NNX11AE84G. L. Rainville, C. Lee, C. Eriksen, and the Seaglider program were supported by NASA grant NNX11AE78G. R. Schmitt was supported by NSF grant OCE-1129646. B. Hodges and D. Fratantoni were supported by NASA grant NNX11AE82G. The Prawler moorings were funded by PMEL. The data analysis was also supported by NASA grant NNX14AH38G

    Super-conservative interpretation of muon g-2 results applied to supersymmetry

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    The recent developments in theory and experiment related to the anomalous magnetic moment of the muon are applied to supersymmetry. We follow a very cautious course, demanding that the supersymmetric contributions fit within five standard deviations of the difference between experiment and the standard model prediction. Arbitrarily small supersymmetric contributions are then allowed, so no upper bounds on superpartner masses result. Nevertheless, non-trivial exclusions are found. We characterize the substantial region of parameter space ruled out by this analysis that has not been probed by any previous experiment. We also discuss some implications of the results for forthcoming collider experiments.Comment: 10 pages, latex, 3 fig
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