339 research outputs found

    Historical fire regimes in southeasern pine savannas

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    Southeastern coastal plain pine savannas lack direct evidence of past fire regimes. As a result, uncertainty exists regarding the range of variation in frequency and seasonal timing of past fire regimes and the relative importance of anthropogenic and lightning-ignited fires. Characterization of past fire regimes is needed for effective restoration and management of these high-biodiversity ecosystems. I used dendrochronologically dated fire scars from stumps of old growth longleaf pines in a large coastal, mainland pine savanna and from dead slash pines on a small, coastal barrier island in north Florida to explore past fire regimes. In the mainland savanna, 71 different fires occurred from 1592-1883, based on a composite record of 109 fire scars from six fire-scarred trees. Almost all (95%) scars occurred during the middle growing season. Only three fires, all in the 1800s after European settlement of the local area, occurred during the dormant season. There was a 2-3 year fire return interval between 1679 and 1868. Variability in fire return intervals was low, with 92% of all fires occurring at \u3c 5 yr intervals. On the barrier island 159 fire scars occurred in 21 separate years from 1864-2000, based on a record of 52 pines scarred during turpentine operations. Two periods of no fire scars corresponded to times of active pine resin extraction on the island (1911-1918, 1948-1958). Mean fire return intervals averaged four years from 1864-1910 and 1919-1947. A longer nine-year fire return interval occurred from 1959-2000. Most (86%) fires recorded in scars occurred during the growing season. The very high frequencies of growing season fires recorded in annual rings of these trees indicate that fire regimes were primarily driven by synoptic climatic conditions rather than by cultural burning practices. Both sites recorded frequent, growing season fires, suggesting that lightning fires were occurring frequently both before and after settlement despite differences in size and landscape context. This direct evidence of fire history in southeastern pine savannas can resolve some outstanding questions regarding ecological fire management. Fire managers now have direct evidence that supports frequent, growing season fires in pine savanna

    . follow the . connect the . . etc . . .

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    Rachael Huffman's M.F.A. thesis exhibition, (. follow the . connect the . . etc . . .), references the stages of gaining knowledge: consciousness, experience, perception, and cognition. The separate components of the show together act as building blocks that nurture learning and allow for re-arrangement of meaning. The exhibition emphasizes the viewing experience instead of the view, placing importance on the process rather than the product. The work relies on viewer participation in order for a concept to transfer, and the work to be realized. Through the use of signage, altered objects, and physically re-orienting furniture, the viewer is invited to re-consider space. A viewer is aware of how their understanding of space can be altered by the senses, physical perspective, movement, and a different frame of thought. Participants leave feel giddy and alive from exercising the brain and realizing it's potential to alter the way they see

    Designing star trackers to meet micro-satellite requirements

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    Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2006.Includes bibliographical references (p. 179-187).Star trackers provide numerous advantages over other attitude sensors because of their ability to provide full, three-axis orientation information with high accuracy and flexibility to operate independently from other navigation tools. However, current star trackers are optimized to maximize accuracy, at the exclusion of all else. Although this produces extremely capable systems, the excessive mass, power consumption, and cost that result are often contradictory to the requirements of smaller space vehicles. Thus, it is of interest to design smaller, lower cost, albeit reduced capability star trackers that can provide adequate attitude and rate determination to small, highly maneuverable, low-cost spacecraft. This thesis discusses the analysis used to select hardware and predict system performance, as well as the algorithms that have been employed to determine attitude information and rotation rates of the spacecraft. Finally, the performance of these algorithms using computer simulated images, nighttime photographs, and images captured directly by star tracker prototypes is presented.by Kara M. Huffman.S.M

    Impact of Vegetable Preparation Method and Taste-Test on Vegetable Preference for First Grade Children in the United States

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    How children rate vegetables may be influenced by the preparation method. The primary objective of this study was for first grade students to be involved in a cooking demonstration and to taste and rate vegetables raw and cooked. First grade children of two classes (N= 52: 18 boys and 34 girls (approximately half Hispanic) that had assented and had signed parental consent participated in the study. The degree of liking a particular vegetable was recorded by the students using a hedonic scale of five commonly eaten vegetables tasted first raw (pre-demonstration) and then cooked (post-demonstration). A food habit questionnaire was filled out by parents to evaluate their mealtime practices and beliefs about their child’s eating habits. Paired sample t-tests revealed significant differences in preferences for vegetables in their raw and cooked states. Several mealtime characteristics were significantly associated with children’s vegetable preferences. Parents who reported being satisfied with how often the family eats evening meals together were more likely to report that their child eats adequate vegetables for their health (p=0.026). Parents who stated that they were satisfied with their child’s eating habits were more likely to report that their child was trying new foods (p<.001). Cooking demonstrations by nutrition professionals may be an important strategy that can be used by parents and teachers to promote vegetable intake. It is important that nutrition professionals provide guidance to encourage consumption of vegetables for parents so that they can model the behavior of healthy food consumption to their children

    A Survey of Availability and Affordability of Polypills for Cardiovascular Disease in Selected Countries.

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    BACKGROUND: The recent inclusion of polypills-fixed-dose combinations of antihypertensive medicines and a statin with or without aspirin-in the World Health Organization's Essential Medicines List (EML) reiterates the potential of this approach to improve global treatment coverage for cardiovascular diseases (CVDs). Although there exists extensive evidence on the effectiveness, safety and acceptability of polypills, there has been no research to date assessing the real-world availability and affordability of polypills globally. METHODS: We conducted a cross-sectional survey, based on the WHO/Health Action International methodology, in 13 countries around the world. In the surveyed countries, we first ascertained whether any polypill was authorised for marketing and/or included in EMLs and clinical guidelines. In each country, we collected retail and price data for polypills from at least one public-sector facility and three private pharmacies using convenience sampling. Polypills were considered unaffordable if the lowest-paid worker spent more than a day's wage to purchase a monthly supply. RESULTS: Polypills were approved for marketing in four of the 13 surveyed countries: Spain, India, Mauritius and Argentina. None of these countries included polypills in national guidelines, formularies, or EMLs. In the four countries, no surveyed public pharmacies stocked polypills. In the private sector, we identified seven unique polypill combinations, marketed by eight different companies. Private sector availability was 100% in Argentina and Spain. Most combinations (n = 5) identified were in India. Combinations found in India and Spain were affordable in the local context. A lowest-paid government worker would spend between 0.2 (India) and 2.8 (Mauritius) days' wages to pay the price for one month's supply of the polypills. Polypills were likely to be affordable if they were manufactured in the same country. CONCLUSION: Low availability and affordability of polypills in the public sector suggest that implementation remains poor globally. Context-specific multi-disciplinary health system research is required to understand factors affecting polypill implementation and to design and evaluate appropriate implementation strategies

    Advancing data science in drug development through an innovative computational framework for data sharing and statistical analysis

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    Background Novartis and the University of Oxford’s Big Data Institute (BDI) have established a research alliance with the aim to improve health care and drug development by making it more efficient and targeted. Using a combination of the latest statistical machine learning technology with an innovative IT platform developed to manage large volumes of anonymised data from numerous data sources and types we plan to identify novel patterns with clinical relevance which cannot be detected by humans alone to identify phenotypes and early predictors of patient disease activity and progression. Method The collaboration focuses on highly complex autoimmune diseases and develops a computational framework to assemble a research-ready dataset across numerous modalities. For the Multiple Sclerosis (MS) project, the collaboration has anonymised and integrated phase II to phase IV clinical and imaging trial data from ≈35,000 patients across all clinical phenotypes and collected in more than 2200 centres worldwide. For the “IL-17” project, the collaboration has anonymised and integrated clinical and imaging data from over 30 phase II and III Cosentyx clinical trials including more than 15,000 patients, suffering from four autoimmune disorders (Psoriasis, Axial Spondyloarthritis, Psoriatic arthritis (PsA) and Rheumatoid arthritis (RA)). Results A fundamental component of successful data analysis and the collaborative development of novel machine learning methods on these rich data sets has been the construction of a research informatics framework that can capture the data at regular intervals where images could be anonymised and integrated with the de-identified clinical data, quality controlled and compiled into a research-ready relational database which would then be available to multi-disciplinary analysts. The collaborative development from a group of software developers, data wranglers, statisticians, clinicians, and domain scientists across both organisations has been key. This framework is innovative, as it facilitates collaborative data management and makes a complicated clinical trial data set from a pharmaceutical company available to academic researchers who become associated with the project. Conclusions An informatics framework has been developed to capture clinical trial data into a pipeline of anonymisation, quality control, data exploration, and subsequent integration into a database. Establishing this framework has been integral to the development of analytical tools
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