5,062 research outputs found

    On the Optimization of Mixture Resolving Signal Processing Structures

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    Mixture resolving signal processing optimization with optimum linear detection operators and mixture resolving estimator

    Warming winters and New Hampshire’s lost ski areas: An integrated case study

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    New Hampshire’s mountains and winter climate support a ski industry that contributes substantially to the state economy. Through more than 70 years of history, this industry has adapted and changed with its host society. The climate itself has changed during this period too, in ways that influenced the ski industry’s development. During the 20th century, New Hampshire’s mean winter temperature warmed about 2.1° C (3.8° F). Much of that change occurred since 1970. The mult‐decadal variations in New Hampshire winters follow global temperature trends. Snowfall exhibits a downward trend, strongest in southern New Hampshire, and also correlates with the North Atlantic Oscillation. Many small ski areas opened during the early years while winters were cold and snowy. As winters warmed, areas in southern or lowelevation locations faced a critical disadvantage. Under pressure from both climate and competition, the number of small ski areas leveled off and then fell steeply after 1970. The number of larger, chairliftoperating ski areas began falling too after 1980. Aprolonged warming period increased the importance of geographic advantages, and also of capital investment in snowmaking, grooming and economic diversification. The consolidation trend continues today. Most of the surviving ski areas are located in the northern mountains. Elsewhere around the state, one can find the remains of “lost” ski areas in places that now rarely have snow suitable for downhill skiing. This case study demonstrates a general approach for conducting integrated empirical research on the human dimensions of climate change

    Early childhood educator training: The value of educating educators on movement, play and physical literacy development - A three country case study.

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    A child's early movement and active play experiences influence their attitudes towards physical activity throughout their childhood and into adulthood (Blair, 1992). Yet, it has been suggested that early childhood educators (ECEs) may not recognize the importance of, or give enough attention to, movement skills and physical development opportunities for young children (Clark, 2014; Whitehead, 2010). The education, or lack thereof, that ECEs receive could be an important factor. International comparisons of overall ECE preparation and training have demonstrated that some countries' ECEs are more highly educated than others (Howells and SÀÀkslahti, 2019). Using a case study approach, this paper conducts an analysis and comparison of three countries to examine the value and role of physical activity/movement education for ECEs to enable them to support physical literacy development in early childhood educational settings. In addition, lessons learned from creating such educational opportunities in the context of their various locations (Manitoba in Canada, Kent in England, and Escambia County, FL in U.S.A.) are discussed. A purposeful sample was used as these countries have relatively low levels of educational requirements for ECEs, yet children start attending early years’ education from the earliest life points (Howells & SÀÀkslahti, 2019)

    Best Management Practices for Corn Production in South Dakota: Irrigation and Salt Management

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    In South Dakota, average annual precipitation ranges from less than 13 inches to nearly 30 inches, generally increasing from west to east (fig. 6.1). However, all regions of South Dakota can experience drought. Irrigation can reduce a crop’s dependence on natural rainfall and improve yields. To best capitalize on investment in irrigation equipment, it has been suggested that one should increase plant populations on irrigated land by 2,000 to 3,000 plants per acre (Aldrich et al. 1975). This chapter discusses how much irrigation water to apply and how to manage the salts contained in the water. If you are planning a new system or expanding an existing system, equipment and management options should be discussed with your local irrigation equipment dealer or Extension educator. A permit may be required to irrigate in South Dakota. For permit requirements, contact the South Dakota Department of Environment and Natural Resources (DENR)

    Multilayered printed circuit boards inspected by X-ray laminography

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    Technique produces high resolution cross-sectional radiographs with close interplane spacing for inspecting multilayer boards to be used in providing circuitry routing and module structural support

    Acquired hypogammaglobulinemia in HIV ‐positive subjects after liver transplantation

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    Introduction As more solid organ transplantations are performed in patients infected with human immunodeficiency virus ( HIV ), post‐transplant complications in this population are becoming better defined. Methods Using serum samples from the Solid Organ Transplantation in HIV : Multi‐Site Study, we studied the epidemiology of acquired hypogammaglobulinemia ( HGG ) after liver transplantation ( LT ) in 79 HIV ‐infected individuals with a median CD 4 count at enrollment of 288 (interquartile range 200–423) cells/ÎŒL. Quantitative immunoglobulin G (IgG) levels before and after LT were measured, with moderate and severe HGG defined as IgG 350–500 mg/dL and <350 mg/dL, respectively. Incidence, risk factors, and associated outcomes of moderate or worse HGG were evaluated using K aplan– M eier estimator and proportional hazards ( PH ) models. Results The 1‐year cumulative incidence of moderate or worse HGG was 12% (95% confidence interval [ CI ]: 6–22%); no new cases were observed between years 1 and 2. In a multivariate PH model, higher pre‐transplant model for end‐stage liver disease score ( P  = 0.04) and treated acute rejection ( P  = 0.04) were both identified as significant predictors of moderate or worse HGG . There was a strong association of IgG levels <500 mg/dL with non‐opportunistic serious infection (hazard ratio [95% CI ]: 3.5 [1.1–10.6]; P  = 0.03) and mortality (3.2 [1.1–9.4]; P  = 0.04). These associations held after adjustment for important determinants of infection and survival among the entire cohort. Conclusion These results suggest that a proportion of HIV ‐positive LT recipients will develop clinically significant HGG after transplantation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/102205/1/tid12139.pd

    Virtual Constraints and Hybrid Zero Dynamics for Realizing Underactuated Bipedal Locomotion

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    Underactuation is ubiquitous in human locomotion and should be ubiquitous in bipedal robotic locomotion as well. This chapter presents a coherent theory for the design of feedback controllers that achieve stable walking gaits in underactuated bipedal robots. Two fundamental tools are introduced, virtual constraints and hybrid zero dynamics. Virtual constraints are relations on the state variables of a mechanical model that are imposed through a time-invariant feedback controller. One of their roles is to synchronize the robot's joints to an internal gait phasing variable. A second role is to induce a low dimensional system, the zero dynamics, that captures the underactuated aspects of a robot's model, without any approximations. To enhance intuition, the relation between physical constraints and virtual constraints is first established. From here, the hybrid zero dynamics of an underactuated bipedal model is developed, and its fundamental role in the design of asymptotically stable walking motions is established. The chapter includes numerous references to robots on which the highlighted techniques have been implemented.Comment: 17 pages, 4 figures, bookchapte
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