581 research outputs found

    Sea Level Rise and Storm Surge Projections for the National Park Service

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    Over one quarter of the units of the National Park System occur along ocean coastlines. Ongoing changes in relative sea levels and the potential for increasing storm surges due to anthropogenic climate change and other factors present challenges to national park managers. This report summarizes work done by the University of Colorado in partnership with the National Park Service (NPS) to provide sea level rise and storm surge projections to coastal area national parks using information from the United Nations Intergovernmental Panel on Climate Change (IPCC) and storm surge scenarios from National Oceanic and Atmospheric Administration (NOAA) models. This research is the first to analyze IPCC and NOAA projections of sea level and storm surge under climate change for U.S. national parks. Results illustrate potential future inundation and storm surge under four greenhouse gas emissions scenarios. In addition to including multiple scenarios, the analysis considers multiple time horizons (2030, 2050 and 2100). This analysis provides sea level rise projections for 118 park units and storm surge projections for 79 of those parks. Within the National Park Service, the National Capital Region is projected to experience the highest average rate of sea level change by 2100. The coastline adjacent to the Outer Banks Group of parks in the Southeast Region is projected to experience the highest sea level rise by 2100. The Southeast Region is projected to experience the highest storm surges based on historical data and NOAA storm surge models. These results are intended to inform park planning and adaptation strategies for resources managed by the National Park Service. Sea level change and storm surge pose considerable risks to infrastructure, archeological sites, lighthouses, forts, and other historic structures in coastal units of the national park system. Understanding projections for continued change can better guide protection of such resources for the benefit of long-term visitor enjoyment and safety

    Solitary coherent structures in viscoelastic shear flow: computation and mechanism

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    Starting from stationary bifurcations in Couette-Dean flow, we compute nontrivial stationary solutions in inertialess viscoelastic circular Couette flow. These solutions are strongly localized vortex pairs, exist at arbitrarily large wavelengths, and show hysteresis in the Weissenberg number, similar to experimentally observed ``diwhirl'' patterns. Based on the computed velocity and stress fields, we elucidate a heuristic, fully nonlinear mechanism for these flows. We propose that these localized, fully nonlinear structures comprise fundamental building blocks for complex spatiotemporal dynamics in the flow of elastic liquids.Comment: 5 pages text and 4 figures. Submitted to Physical Review Letter

    Reproductive Aging Influences Ovarian Function in Beef Cows

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    Anti-MĂĽllerian Hormone (AMH) has been associated with follicle number and age of the ovary. Therefore, our hypothesiswas that AMH was a biomarker for both follicle number and ovarian function in the beef cow. Ovaries were collected by flank laparotomy. The number of follicles increased as cows aged from 1.5 to 6 years and began to decrease thereafter; however, the size of the ovary continued to increase with advanced age. Expression of the AMH gene increased with increasing follicle number in 2-year-old beef cows. These results suggest that heifers with larger ovaries will have greater numbers of follicles and greater productivity, allowing them to stay in the production herd longer. AMH could be used to identify heifers of high reproductive potential at a very young age

    Numerical simulation of biofilm formation in a microchannel

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    The focus of this paper is the numerical solution of a pore-scale model for the growth of a permeable biofilm. The model includes water flux inside the biofilm, different biofilm components, and shear stress on the biofilm-water interface. To solve the resulting highly coupled system of model equations, we propose a splitting algorithm. The Arbitrary Lagrangian Eulerian (ALE) method is used to track the biofilm-water interface. Numerical simulations are performed using physical parameters from the existing literature. Our computations show the effect of biofilm permeability on the nutrient transport and on its growth

    Resolving Sirius-like binaries with the Hubble Space Telescope

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    We have imaged seventeen recently discovered Sirius-like binary systems with HST/WFPC2 and resolved the white dwarf secondary in eight cases. Most of the implied orbital periods are of order several hundred years, but in three cases (56 Per, Zeta Cygni and REJ1925-566) the periods are short enough that it may be possible to detect orbital motion within a few years. It will then be possible to derive dynamically determined masses for the white dwarfs, and potentially these stars could be used as stringent tests of the mass-radius relation and initial-final mass relation.Comment: To appear in Proceedings of the 12th European Workshop on White Dwarfs, eds. H. Shipman and J. Provenca

    A Multi-Site Analysis of the Prevalence of Food Insecurity in the United States, before and during the COVID-19 Pandemic

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    Background: The coronavirus disease 2019 (COVID-19) pandemic profoundly affected food systems including food security. Understanding how the COVID-19 pandemic impacted food security is important to provide support and identify long-term impacts and needs. Objective: The National Food Access and COVID research Team (NFACT) was formed to assess food security over different US study sites throughout the pandemic, using common instruments and measurements. This study presents results from 18 study sites across 15 states and nationally over the first year of the COVID-19 pandemic. Methods: A validated survey instrument was developed and implemented in whole or part through an online survey of adults across the sites throughout the first year of the pandemic, representing 22 separate surveys. Sampling methods for each study site were convenience, representative, or high-risk targeted. Food security was measured using the USDA 6-item module. Food security prevalence was analyzed using ANOVA by sampling method to assess statistically significant differences. Results: Respondents (n = 27,168) indicate higher prevalence of food insecurity (low or very low food security) since the COVID-19 pandemic, compared with before the pandemic. In nearly all study sites, there is a higher prevalence of food insecurity among Black, Indigenous, and People of Color (BIPOC), households with children, and those with job disruptions. The findings demonstrate lingering food insecurity, with high prevalence over time in sites with repeat cross-sectional surveys. There are no statistically significant differences between convenience and representative surveys, but a statistically higher prevalence of food insecurity among high-risk compared with convenience surveys. Conclusions: This comprehensive study demonstrates a higher prevalence of food insecurity in the first year of the COVID-19 pandemic. These impacts were prevalent for certain demographic groups, and most pronounced for surveys targeting high-risk populations. Results especially document the continued high levels of food insecurity, as well as the variability in estimates due to the survey implementation method
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