2,231 research outputs found

    Rural Land-Use Trends in the Conterminous United States, 1950-2000.

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    In order to understand the magnitude, direction, and geographic distribution of land-use changes, we evaluated land-use trends in U.S. counties during the latter half of the 20th century. Our paper synthesizes the dominant spatial and temporal trends in population, agriculture, and urbanized land uses, using a variety of data sources and an ecoregion classification as a frame of reference. A combination of increasing attractiveness of nonmetropolitan areas in the period 1970–2000, decreasing household size, and decreasing density of settlement has resulted in important trends in the patterns of developed land. By 2000, the area of low-density, exurban development beyond the urban fringe occupied nearly 15 times the area of higher density urbanized development. Efficiency gains, mechanization, and agglomeration of agricultural concerns has resulted in data that show cropland area to be stable throughout the Corn Belt and parts of the West between 1950 and 2000, but decreasing by about 22% east of the Mississippi River. We use a regional case study of the Mid-Atlantic and Southeastern regions to focus in more detail on the land-cover changes resulting from these dynamics. Dominating were land-cover changes associated with the timber practices in the forested plains ecoregions and urbanization in the piedmont ecoregions. Appalachian ecoregions show the slowest rates of landcover change. The dominant trends of tremendous exurban growth, throughout the United States, and conversion and abandonment of agricultural lands, especially in the eastern United States, have important implications because they affect large areas of the country, the functioning of ecological systems, and the potential for restoratio

    Parent Perception of Child’s Developmental and Coordination Skills Related to Participation in the Gymnastics through Early Movement Program

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    This study aims to evaluate the effectiveness of the Gymnastics through Early Movement program in increasing motor ability in children with motor developmental delay or coordination deficits through the perception of the parent. The Gymnastics through Early Movement program is a therapeutic gymnastics program developed by a pediatric nurse and professional member of United States of America Gymnastics. The program was designed specifically for pre-school aged children who experience motor challenges. Over the course of six weeks, each 45-minute lesson included activities and obstacles focusing on fundamental preschool gymnastics skills to develop strength, coordination, and flexibility. The American Academy of Pediatrics supports child participation in sports to increase development in all areas. Gymnastics is one of the most comprehensive sports available to children, incorporating strength, flexibility, and balance to develop a range of motor and coordination skills as well as improving body awareness and posture. Evidence has shown participation in early intervention programs that address mental or neuromuscular and movement-related functions result in significant improvement (Park, Maitra, Achon, Loyola, Rincon, 2014). The Developmental Coordination Disorder Questionnaire (DCDQ) was used to evaluate the change in parent perception of their children’s motor and coordination skills after participating in the Gymnastics through Early Movement program. Results demonstrated positive findings in the areas of general coordination and motor control. Specific improvements were found in post-test scores regarding endurance, posture, and agility. The fine motor category showed increased mean scores from 8 to 8.3. Mean scores for coordination increased from 12.6 to 14.3 and total score means increased from 37 to 41. All participants reported the Gymnastics through Early Movement program as valuable and fun for their children

    Sub-grid variability in ammonia concentrations and dry deposition in an upland landscape

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    Turbofan noise generation. Volume 2: Computer programs

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    The use of a package of computer programs developed to calculate the in duct acoustic mods excited by a fan/stator stage operating at subsonic tip speed is described. The following three noise source mechanisms are included: (1) sound generated by the rotor blades interacting with turbulence ingested into, or generated within, the inlet duct; (2) sound generated by the stator vanes interacting with the turbulent wakes of the rotor blades; and (3) sound generated by the stator vanes interacting with the velocity deficits in the mean wakes of the rotor blades. The computations for three different noise mechanisms are coded as three separate computer program packages. The computer codes are described by means of block diagrams, tables of data and variables, and example program executions; FORTRAN listings are included

    Colorado's wildland-urban interface, current and projected

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    WUI is the wildland-urban interface. It is the area where homes and urban sprawl press against the wildland, and includes both interface and intermix communities.Map created 23 October 2007 by D. Theobald, Colorado State University.WUI is the wildland-urban interface. It is the area where homes and urban sprawl press against the wildland, and includes both interface and intermix communities

    Fast Heuristic and Exact Algorithms for Two-Level Hazard-Free Logic Minimization

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    None of the available minimizers for 2-level hazard-free logic minimization can synthesize very large circuits. This limitation has forced researchers to resort to manual and automated circuit partitioning techniques. This paper introduces two new 2-level logic minimizers:ESPRESSO-HF, a heuristic method which is loosely based on ESPRESSO-II, and IMPYMIN, an exact method based on implicit data structures. Both minimizers can solve all currently available examples, which range up to 32 inputs and 33 outputs.These include examples that have never been solved before.For examples that can be solved by other minimizers our methods are several orders of magnitude faster. As by-products of these algorithms, we also present two additional results. First, we introduce a fast new algorithm to check if a hazard-free covering problem can feasibly be solved. Second, we introduce a novel formulation of the 2-level hazard-free logic minimization problem by capturing hazard-freedom constraints within a synchronous function by adding new variables

    Fast Heuristic and Exact Algorithms for Two-Level Hazard-Free Logic Minimization

    Get PDF
    None of the available minimizers for 2-level hazard-free logic minimization can synthesize very large circuits. This limitation has forced researchers to resort to manual and automated circuit partitioning techniques. This paper introduces two new 2-level logic minimizers:ESPRESSO-HF, a heuristic method which is loosely based on ESPRESSO-II, and IMPYMIN, an exact method based on implicit data structures. Both minimizers can solve all currently available examples, which range up to 32 inputs and 33 outputs.These include examples that have never been solved before.For examples that can be solved by other minimizers our methods are several orders of magnitude faster. As by-products of these algorithms, we also present two additional results. First, we introduce a fast new algorithm to check if a hazard-free covering problem can feasibly be solved. Second, we introduce a novel formulation of the 2-level hazard-free logic minimization problem by capturing hazard-freedom constraints within a synchronous function by adding new variables

    Effects of Breed and Stage of Growing Season on the Metabolic Profile of Sheep Grazing Moorland

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    Previous studies have shown that the diet of sheep grazing heather moorland is affected by season (Grant et al., 1987) and the proportion of Calluna vulgaris cover (Osoro et al., 2000). In order to investigate the impact of these factors on the associated nutrient supply of animals grazing heathland, blood samples were taken to monitor the metabolic status of different breeds of sheep at different stages of the growing season when grazing sites with different proportions of heather cover
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