Recent research has indicated an increase in the likelihood and impact of tree failure. The potential for trees to fail relates to various biomechanical and physical factors. Strikingly, there seems to be an absence of tree risk assessment methods supported by observations, despite an increasing availability of variables and parameters measured by scientists, arborists and practitioners. Current urban tree risk assessments vary due to differences in experience, training, and personal opinions of assessors. This stresses the need for a more objective method to assess the hazardousness of urban trees. The aim of this study is to provide an overview of factors that influence tree failure including stem failure, root failure and branch failure. A systematic literature review according to the PRISMA guidelines has been performed in databases, supported by backward referencing: 161 articles were reviewed revealing 142 different factors which influenced tree failure. A meta-analysis of effect sizes and p-values was executed on those factors which were associated directly with any type of tree failure. Bayes Factor was calculated to assess the likelihood that the selected factors appear in case of tree failure. Publication bias was analysed visually by funnel plots and results by regression tests. The results provide evidence that the factors Height and Stem weight positively relate to stem failure, followed by Age, DBH, DBH squared times H, and Cubed DBH (DBH3) and Tree weight. Stem weight and Tree weight were found to relate positively to root failure. For branch failure no relating factors were found. We recommend that arborists collect further data on these factors. From this review it can further be concluded that there is no commonly shared understanding, model or function available that considers all factors which can explain the different types of tree failure. This complicates risk estimations that include the failure potential of urban trees.
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This paper introduces a novel distributed algorithm designed to optimize the deployment of access points within Mobile Ad Hoc Networks (MANETs) for better service quality in infrastructure less environments. The algorithm operates based on local, independent execution by each network node, thus ensuring a high degree of scalability and adaptability to changing network conditions. The primary focus is to match the spatial distribution of access points with the distribution of client devices while maintaining strong connectivity to the network root. Using autonomous decision-making and choreographed path-planning, this algorithm bridges the gap between demand-responsive network service provision and the maintenance of crucial network connectivity links. The assessment of the performance of this approach is motivated by using numerical results generated by simulations.
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At present, leading international agencies, such as the United Nations Environmental Programme, are largely focused on what they claim to be ‘win-win’ scenarios of ‘sustainable development’ rhetoric. These combine social, economic and environmental objectives. However, as noted by the ‘Scientists’ Warning to Humanity’, environmental integrity is the essential precondition for the healthy functioning of social and economic systems, and thus environmental protection needs to be prioritized in policy and practice. Ecological sustainability cannot be reached without realizing that population growth and economic growth, with attendant increased rates of depletion of natural resources, pollution, and general environmental degradation, are the root causes of unsustainability. This article argues that to strategically address ecological unsustainability, the social, economic and political barriers to addressing the current economic model and population growth need to be overcome. Strategic solutions proposed to the current neoliberal economy are generic – namely, degrowth, a steady-state economy, and a ‘circular economy’. Solutions to demographic issues must be sensitive to the countries' cultural, social, political and economic factors to be effective as fertility differs from country to country, and culture to culture. As discussed here, Mediterranean countries have the lowest fertility in the world, while many countries in Africa, and some in Asia, South America have stable but consistently high birthrates. This is discussed using three case studies - Tanzania, Italy, and Cambodia, focusing on the "best case" policy practice that offers more realistic hope for successful sustainability. https://doi.org/10.1007/s41207-019-0139-4 LinkedIn: https://www.linkedin.com/in/helenkopnina/
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