1,960 research outputs found

    New Insights From Pre-Columbian Land Use and Fire Management in Amazonian Dark Earth Forests

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    This is the final version of the article. Available from Frontiers Media via the DOI in this record.Anthropogenic climate change driven by increased carbon emissions is leading to more severe fire seasons and increasing the frequency of mega-fires in the Amazon. This has the potential to convert Amazon forests from net carbon sinks to net carbon sources. Although modern human influence over the Earth is substantial, debate remains over when humans began to dominate Earth's natural systems. To date, little is known about the history of human land use in key regions like the Amazon. Here, we examine the history of human occupation from a ~8,500 year-old sediment core record from Lake Caranã (LC) in the eastern Amazon. The onset of pre-Columbian activity at LC (~4,500 cal yr B.P.) is associated with the beginning of fire management and crop cultivation, later followed by the formation of Amazonian Dark Earth soils (ADEs) ~2,000 cal yr B.P. Selective forest enrichment of edible plants and low-severity fire activity altered the composition and structure of forests growing on ADEs (ADE forests) making them more drought susceptible and fire-prone. Following European colonization (1661 A.D.), the Amazon rubber boom (mid-1800s to 1920 A.D.) is associated with record-low fire activity despite drier regional climate, indicating fire exclusion. The formation of FLONA Reserve in 1974 A.D. is accompanied by the relocation of traditional populations and a fire suppression policy. Despite suppression efforts, biomass burning and fire severity in the past decade is higher than any other period in the record. This is attributed to combined climate and human factors which create optimal conditions for mega-fires in ADE forests and threatens to transform the Amazon from a net carbon sink to a net carbon source. To help mitigate the occurrence of mega-fires, a fire management policy reducing fire-use and careful fire management for farming may help to reduce fuel loads and the occurrence of mega-fires in fire-prone ADE forests. As both natural and anthropogenic pressures are projected to increase in the Amazon, this study provides valuable insights into the legacy of past human land use on modern ADE forest composition, structure, and flammability that can inform ecological benchmarks and future management efforts in the eastern Amazon.Funding for this research was supported by the PAST (Pre-Columbian Amazon-Scale Transformations) European Research Council Consolidator Grant to JI (ERC_Cog 616179). Research was conducted under permit 01506.004836/2014-69 from the Instituto do Patrimônio Histórico e Artístico Nacional (IPHAN) and ICMBio permit 106/14-FNT. We thank all residents of Maguarí and Jamaraquá community for their hospitality and help

    How manipulating task constraints in small-sided and conditioned games shapes emergence of individual and collective tactical behaviours in football: A systematic review

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    Background: Small-Sided and Conditioned Games are characterised by modifications of field dimensions, number of players, rules of the game, manipulations used to shape the key task constraints that performers need to satisfy in practice. Evidence has already demonstrated the importance of designing practice to enhance understanding of tactical behaviours in football, but there is a lack of information about how coaches can manipulate task constraints to support tactical learning. Objective: To investigate which task constraints have been most often manipulated in studies of SSCGs; and what impact each manipulation had on emerging tactical behaviours, technical–tactical actions, and positional relationships between players. Methods: PubMed, Web of Science, Scielo, and Academic Google databases were searched for relevant reports without time limits. The criteria adopted for inclusion were: a) studies performed with football players; b) studies that included SSCGs as an evaluation method; c) studies that investigated tactical behaviours in SSCGs; and d), articles in English and Portuguese. Results: The electronic database search included 24 articles in the review. Of these, five manipulated field dimensions, six manipulated number of players involved, five manipulated field dimensions and number of players, five used different scoring targets, two altered the number of players and scoring target, and one manipulated the number of players, field dimension, and scoring target. Conclusion: Among the task constraints analyzed in this systematic review, manipulation of number of players and playing field dimensions concomitantly occurred most frequentl

    How manipulating task constraints in small-sided and conditioned games shapes emergence of individual and collective tactical behaviours in football: A systematic review

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    Background: Small-Sided and Conditioned Games are characterised by modifications of field dimensions, number of players, rules of the game, manipulations used to shape the key task constraints that performers need to satisfy in practice. Evidence has already demonstrated the importance of designing practice to enhance understanding of tactical behaviours in football, but there is a lack of information about how coaches can manipulate task constraints to support tactical learning. Objective: To investigate which task constraints have been most often manipulated in studies of SSCGs; and what impact each manipulation had on emerging tactical behaviours, technical–tactical actions, and positional relationships between players. Methods: PubMed, Web of Science, Scielo, and Academic Google databases were searched for relevant reports without time limits. The criteria adopted for inclusion were: a) studies performed with football players; b) studies that included SSCGs as an evaluation method; c) studies that investigated tactical behaviours in SSCGs; and d), articles in English and Portuguese. Results: The electronic database search included 24 articles in the review. Of these, five manipulated field dimensions, six manipulated number of players involved, five manipulated field dimensions and number of players, five used different scoring targets, two altered the number of players and scoring target, and one manipulated the number of players, field dimension, and scoring target. Conclusion: Among the task constraints analyzed in this systematic review, manipulation of number of players and playing field dimensions concomitantly occurred most frequentl

    Widespread forest vertebrate extinctions induced by a mega hydroelectric dam in lowland Amazonia

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    Mega hydropower projects in tropical forests pose a major emergent threat to terrestrial and freshwater biodiversity worldwide. Despite the unprecedented number of existing, underconstruction and planned hydroelectric dams in lowland tropical forests, long-term effects on biodiversity have yet to be evaluated. We examine how medium and large-bodied assemblages of terrestrial and arboreal vertebrates (including 35 mammal, bird and tortoise species) responded to the drastic 26-year post-isolation history of archipelagic alteration in landscape structure and habitat quality in a major hydroelectric reservoir of Central Amazonia. The Balbina Hydroelectric Dam inundated 3,129 km2 of primary forests, simultaneously isolating 3,546 land-bridge islands. We conducted intensive biodiversity surveys at 37 of those islands and three adjacent continuous forests using a combination of four survey techniques, and detected strong forest habitat area effects in explaining patterns of vertebrate extinction. Beyond clear area effects, edge-mediated surface fire disturbance was the most important additional driver of species loss, particularly in islands smaller than 10 ha. Based on species-area models, we predict that only 0.7% of all islands now harbor a species-rich vertebrate assemblage consisting of ≥80% of all species. We highlight the colossal erosion in vertebrate diversity driven by a man-made dam and show that the biodiversity impacts of mega dams in lowland tropical forest regions have been severely overlooked. The geopolitical strategy to deploy many more large hydropower infrastructure projects in regions like lowland Amazonia should be urgently reassessed, and we strongly advise that long-term biodiversity impacts should be explicitly included in pre-approval environmental impact assessments

    Concurrent use of prescription drugs and herbal medicinal products in older adults: A systematic review

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    This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 International License (http://creativecommons.org/licenses/by-nc/4.0/), which permits any noncommercial use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.The use of herbal medicinal products (HMPs) is common among older adults. However, little is known about concurrent use with prescription drugs as well as the potential interactions associated with such combinations. Objective Identify and evaluate the literature on concurrent prescription and HMPs use among older adults to assess prevalence, patterns, potential interactions and factors associated with this use. Methods Systematic searches in MEDLINE, PsycINFO, EMBASE, CINAHL, AMED, Web of Science and Cochrane from inception to May 2017 for studies reporting concurrent use of prescription medicines with HMPs in adults (≥65 years). Quality was assessed using the Joanna Briggs Institute checklists. The Evidence for Policy and Practice Information and Co-ordinating Centre (EPPI-Centre) three stage approach to mixed method research was used to synthesise data. Results Twenty-two studies were included. A definition of HMPs or what was considered HMP was frequently missing. Prevalence of concurrent use by older adults varied widely between 5.3% and 88.3%. Prescription medicines most combined with HMPs were antihypertensive drugs, beta blockers, diuretics, antihyperlipidemic agents, anticoagulants, analgesics, antihistamines, antidiabetics, antidepressants and statins. The HMPs most frequently used were: ginkgo, garlic, ginseng, St John’s wort, Echinacea, saw palmetto, evening primrose oil and ginger. Potential risks of bleeding due to use of ginkgo, garlic or ginseng with aspirin or warfarin was the most reported herb-drug interaction. Some data suggests being female, a lower household income and less than high school education were associated with concurrent use. Conclusion Prevalence of concurrent prescription drugs and HMPs use among older adults is substantial and potential interactions have been reported. Knowledge of the extent and manner in which older adults combine prescription drugs will aid healthcare professionals can appropriately identify and manage patients at risk.Peer reviewedFinal Published versio

    Illustrating risk difference and number needed to treat from a randomized controlled trial of spinal manipulation for cervicogenic headache

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    <p>Abstract</p> <p>Background</p> <p>The number needed to treat (NNT) for one participant to benefit is considered a useful, clinically meaningful way of reporting binary outcomes from randomized trials. Analysis of continuous data from our randomized controlled trial has previously demonstrated a significant and clinically important difference favoring spinal manipulation over a light massage control.</p> <p>Methods</p> <p>Eighty participants were randomized to receive spinal manipulation or a light massage control (n = 40/group). Improvements in cervicogenic headache pain (primary outcome), disability, and number in prior four weeks were dichotomized into binary outcomes at two thresholds: 30% representing minimal clinically important change and 50% representing clinical success. Groups were compared at 12 and 24-week follow-up using binomial regression (generalized linear models) to compute the adjusted risk difference (RD) between groups and number needed to treat (NNT) after adjusting for baseline differences between groups. Results were compared to logistic regression results.</p> <p>Results</p> <p>For headache pain, clinically important improvement (30% or 50%) was more likely for spinal manipulation: adjusted RD = 17% to 27% and NNT = 3.8 to 5.8 (p = .005 to .028). Some statistically significant results favoring manipulation were found for headache disability and number.</p> <p>Conclusion</p> <p>Spinal manipulation demonstrated a benefit in terms of a clinically important improvement of cervicogenic headache pain. The use of adjusted NNT is recommended; however, adjusted RD may be easier to interpret than NNT. The study demonstrated how results may depend on the threshold for dichotomizing variables into binary outcomes.</p> <p>Trial Registration</p> <p>ClinicalTrials.gov NLM identifier NCT00246350.</p
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