837 research outputs found

    Constructing computer virus phylogenies

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    There has been much recent algorithmic work on the problem of reconstructing the evolutionary history of biological species. Computer virus specialists are interested in finding the evolutionary history of computer viruses - a virus is often written using code fragments from one or more other viruses, which are its immediate ancestors. A phylogeny for a collection of computer viruses is a directed acyclic graph whose nodes are the viruses and whose edges map ancestors to descendants and satisfy the property that each code fragment is "invented" only once. To provide a simple explanation for the data, we consider the problem of constructing such a phylogeny with a minimum number of edges. In general this optimization problem is NP-complete; some associated approximation problems are also hard, but others are easy. When tree solutions exist, they can be constructed and randomly sampled in polynomial time

    Psychosocial Correlates of Physical Activity and Sedentary Leisure Habits in Young Adolescents: The Teens Eating for Energy and Nutrition at School Study

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    BACKGROUND: Low levels of physical activity (PA) and highly sedentary leisure habits (SLH) in youth may establish behavioral patterns that will predispose youth to increased chronic disease risk in adulthood. The purpose of this paper was to examine associations of demographic and psychosocial factors with self-reported PA and SLH in young adolescents. METHODS: A general linear mixed model predicted self-reported PA and SLH in the spring from demographic and psychosocial variables measured the previous fall in 3798 seventh grade students. RESULTS: PA and SLH differed by race, with Caucasian students reporting among the highest PA and lowest SLH. Perceptions of higher academic rank or expectations predicted higher PA and lower SLH. Depressive symptomatology predicted higher SLH scores but not PA. Higher self-reported value of health, appearance, and achievement predicted higher PA and lower SLH in girls. Girls who reported that their mothers had an authoritative parenting style also reported higher PA and lower SLH. CONCLUSIONS: Determinants of PA and SLH appear to differ from each other, particularly in boys. Development of effective programs to increase PA and/or decrease SLH in young adolescents should be based on a clear understanding of the determinants of these behaviors

    Wound care challenges in children and adults with spina bifida: An open-cohort study

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    Skin breakdown is a frequent concern for individuals with spina bifida. We explored wound incidence in patients with spina bifida and how it varies across a person\u27s life span and functional neurologic level. We examined the settings in which skin breakdown most commonly occurred, looking for evidence of chronic, non-healing wounds. We also sought to develop criteria to improve wound monitoring. We identified reported wound episodes in an open-cohort study over a 13-year period, examining the hospital and outpatient clinical records of spina bifida patients at Children\u27s National Medical Center (CNMC). Current age, age at wound presentation, sex, weight, functional neurologic level, wound location, setting in which the wound was acquired, the development of a chronic wound, and presence of a shunt were recorded. Of the 376 patients in our clinical population, 123 (average age: 18.8 years, range: infancy–56 years) developed a total of 375 wounds; the majority of patients who developed one wound went on to develop one or more additional wounds, and 20 patients developed chronic wounds. Our data suggest that age bracket (adolescents), wheelchair use, and bare feet, as well as possibly obesity and reduced executive functioning, are key risk factors for wound development. These findings have led to a focused effort to increase wound education and prevention. In addition we report on our early experience using a wound care specialist to champion this initiative

    An integrated assessment of the potential impacts of climate change on Indiana forests

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    Forests provide myriad ecosystem services, many of which are vital to local and regional economies. Consequently, there is a need to better understand how predicted changes in climate will impact forests dynamics and the implications of such changes for society as a whole. Here we focus on the impacts of climate change on Indiana forests, which are representative of many secondary growth broadleaved forests in the greater Midwest region in terms of their land use history and current composition. We find that predicted changes in climate for the state – warmer and wetter winters/springs and hotter and potentially drier summers – will dramatically shape forest communities, resulting in new assemblages of trees and wildlife that differ from forest communities of the past or present. Overall, suitable habitat is expected to decline for 17-29 percent of tree species and increase for 43-52 percent of tree species in the state, depending on the region and climate scenario. Such changes have important consequences for wildlife that depend on certain tree species or have ranges with strong sensitivities to climate. Additionally, these changes will have potential economic impacts on Indiana industries that depend on forest resources and products (both timber and non-timber). Finally, we offer some practical suggestions on how management may minimize the extent of climate-induced ecological impacts, and highlight a case study from a tree planting initiative currently underway in the Patoka River National Wildlife Refuge and Management Area

    Indiana\u27s Future Forests: A Report from the Indiana Climate Change Impacts Assessment

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    Over the next century, rising temperatures and changing precipitation patterns across the Midwest will likely have profound consequences for Indiana’s forests. Such changes include shifts in the distributions and abundances of trees, understory plants and wildlife, as well as changes to the environmental, economic and cultural benefits these forests provide. This report from the Indiana Climate Change Impacts Assessment (IN CCIA) examines the direct and indirect impacts that climate change is expected to have on Indiana’s forests. The report specifically addresses forest regeneration, forest composition, tree growth and harvest, wildlife habitat and forest products

    Assessing copper fertility of intrusive rocks using field portable X-Ray fluorescence (pXRF) data

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    Based on a global compilation of whole-rock geochemical data, Sr/Y and Sr/MnO are identified as effective discriminators between ore-forming and unprospective intrusions in the porphyry Cu setting. Intrusive rocks are classified into three fertility groups prospective, unprospective and mixed-signal designed to assist explorers as a discrimination tool, narrowing the exploration search space in porphyry Cu districts.Portable X-ray fluorescence (pXRF) data of Sr, Y and MnO were collected on pulp powders and rock slabs from six porphyry Cu (±Mo ± Au) districts. Pre- and post-mineralization intrusions from porphyry Cu districts have lower Sr/Y and Sr/MnO values than syn-mineralization intrusions from the same districts, although absolute values are variable between districts.pXRF data were compared to conventional whole-rock data to determine if pXRF data were appropriate substitutes for conventional whole-rock methods of evaluating the ore-forming potential of intrusive rocks. pXRF data collected on pulp material were found to be more accurate (within 16% of conventional methods) and more precise

    Interacting with Fictions:The Role of Pretend Play in Theory of Mind Acquisition

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    Pretend play is generally considered to be a developmental landmark in Theory of Mind acquisition. The aim of the present paper is to offer a new account of the role of pretend play in Theory of Mind development. To this end I combine Hutto and Gallagher’s account of social cognition development with Matravers’ recent argument that the cognitive processes involved in engagement with narratives are neutral regarding fictionality. The key contribution of my account is an analysis of pretend play as interaction with fictions. I argue that my account offers a better explanation of existing empirical data on the development of children’s pretend play and Theory of Mind than the competing theories from Leslie, Perner and Harris
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