326 research outputs found

    Developing Retina and PNS Segments for Transplantation Into the Adult Host Eye: Reconstruction of the Mammalian Visual System. 1. Methodology

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    Various techniques have been explored to determine the uses and limitations of techniques that enable the adult CNS to regenerate, but relatively little attention has been given to the consideration of a "reconstructed" visual system. Using this approach, one can design experiments to study the uses of exogenous tissues in reestablishing neuronal circuits that have been damaged. Toward this end, experiments were designed to determine whether embryonic retinal ganglion cells can project axons into a grafted PNS "bridge", and enter adult host targets that were partially deafferented. Embryonic eyes of E11, E14, E18 and E21 rats were sutured to peripheral nerve segments which served as bridges between the host eye and frontal cortex. Projections between the developing retina and the host brain could then be evaluated using HRP tracing techniques. From a methodological standpoint, the preparations are 65% effective; i.e., a viable bridge results between the embryonic eye and the host forebrain. The results presented in the accompanying paper demonstrate that the technique can yield results indicative of embryonic retinal development and axonal projection through the graft and into the host brain. This partial reconstruction of the visual system may prove a useful tool in understanding the uses and limitations of grafting in the CNS

    A new perspective on the competitiveness of nations

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    The capability of firms to survive and to have a competitive advantage in global markets depends on, amongst other things, the efficiency of public institutions, the excellence of educational, health and communications infrastructures, as well as on the political and economic stability of their home country. The measurement of competitiveness and strategy development is thus an important issue for policy-makers. Despite many attempts to provide objectivity in the development of measures of national competitiveness, there are inherently subjective judgments that involve, for example, how data sets are aggregated and importance weights are applied. Generally, either equal weighting is assumed in calculating a final index, or subjective weights are specified. The same problem also occurs in the subjective assignment of countries to different clusters. Developed as such, the value of these type indices may be questioned by users. The aim of this paper is to explore methodological transparency as a viable solution to problems created by existing aggregated indices. For this purpose, a methodology composed of three steps is proposed. To start, a hierarchical clustering analysis is used to assign countries to appropriate clusters. In current methods, country clustering is generally based on GDP. However, we suggest that GDP alone is insufficient for purposes of country clustering. In the proposed methodology, 178 criteria are used for this purpose. Next, relationships between the criteria and classification of the countries are determined using artificial neural networks (ANNs). ANN provides an objective method for determining the attribute/criteria weights, which are, for the most part, subjectively specified in existing methods. Finally, in our third step, the countries of interest are ranked based on weights generated in the previous step. Beyond the ranking of countries, the proposed methodology can also be used to identify those attributes that a given country should focus on in order to improve its position relative to other countries, i.e., to transition from its current cluster to the next higher one

    The competitiveness of nations and implications for human development

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    This is the post-print version of the final paper published in Socio-Economic Planning Sciences. The published article is available from the link below. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. Copyright @ 2010 Elsevier B.V.Human development should be the ultimate objective of human activity, its aim being healthier, longer, and fuller lives. Thus, if the competitiveness of a nation is properly managed, enhanced human welfare should be the key expected consequence. The research described here explores the relationship between the competitiveness of a nation and its implications for human development. For this purpose, 45 countries were evaluated initially using data envelopment analysis. In this stage, global competitiveness indicators were taken as input variables with human development index indicators as output variables. Subsequently, an artificial neural network analysis was conducted to identify those factors having the greatest impact on efficiency scores

    Characteristics and age-related injury patterns of maxillofacial fractures in children and adolescents:A multicentric and prospective study

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    BACKGROUND/AIMS: Paediatric maxillofacial trauma accounts for 15% of all maxillofacial trauma but remains a leading cause of mortality. The aim of this prospective, multicentric epidemiological study was to analyse the characteristics of maxillofacial fractures in paediatric patients managed in 14 maxillofacial surgery departments on five continents over a 1‐year period. METHODS: The following data were collected: age (preschool [0–6 years], school age [7–12 years], and adolescent [13–18 years]), cause and mechanism of the maxillofacial fracture, alcohol and/or drug abuse at the time of trauma, fracture site, Facial Injury Severity Scale score, associated injuries, day of the maxillofacial trauma, timing and type of treatment, and length of hospitalization. Statistical analyses were performed using SPSS software. RESULTS: Between 30 September 2019 and 4 October 2020, 322 patients (male:female ratio, 2.3:1) aged 0–18 years (median age, 15 years) were hospitalized with maxillofacial trauma. The most frequent causes of the trauma were road traffic accidents (36%; median age, 15 years), followed by falls (24%; median age, 8 years) and sports (21%; median age, 14 years). Alcohol and/or drug abuse was significantly associated with males (p < .001) and older age (p < .001). Overall, 474 fractures were observed (1.47 per capita). The most affected site was the mandibular condyle in children <13 years old and the nose in adolescents. The proportion of patients who underwent open reduction and internal fixation increased with age (p < .001). CONCLUSION: The main cause of paediatric maxillofacial fractures was road traffic accidents, with the highest rates seen in African and Asian centres, and the frequency of such fractures increased with age. Falls showed an inverse association with age and were the leading cause of trauma in children 0–6 years of age. The choice of treatment varies with age, reflecting anatomical and etiological changes towards patterns more similar to those seen in adulthood

    A multicentric, prospective study on oral and maxillofacial trauma in the female population around the world

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    BACKGROUND/AIMS: Approximately 20% of patients with maxillofacial trauma are women, but few articles have analysed this. The aim of this multicentric, prospective, epidemiological study was to analyse the characteristics of maxillofacial fractures in the female population managed in 14 maxillofacial surgery departments on five continents over a 1‐year period. METHODS: The following data were collected: age (0–18, 19–64, or ≥65 years), cause and mechanism of the maxillofacial fracture, alcohol and/or drug abuse at the time of trauma, fracture site, Facial Injury Severity Scale score, associated injury, day of trauma, timing and type of treatment, and length of hospitalization. RESULTS: Between 30 September 2019 and 4 October 2020, 562 of 2387 patients hospitalized with maxillofacial trauma were females (24%; M: F ratio, 3.2:1) aged between 1 and 96 years (median age, 37 years). Most fractures occurred in patients aged 20–39 years. The main causes were falls (43% [median age, 60.5 years]), which were more common in Australian, European and American units (p < .001). They were followed by road traffic accidents (35% [median age, 29.5 years]). Assaults (15% [median age, 31.5 years]) were statistically associated with alcohol and/or drug abuse (p < .001). Of all patients, 39% underwent open reduction and internal fixation, 36% did not receive surgical treatment, and 25% underwent closed reduction. CONCLUSION: Falls were the main cause of maxillofacial injury in the female population in countries with ageing populations, while road traffic accidents were the main cause in African and some Asian centres, especially in patients ≤65 years. Assaults remain a significant cause of trauma, primarily in patients aged 19–64 years, and they are related to alcohol use

    Transport infrastructure: making more sustainable decisions for noise reduction

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    There is a global and growing sustainability agenda for surface transport yet there are no specific means of assessing the relative sustainability of infrastructure equipment. Transport noise reduction devices are a significant part of the surface transport infrastructure: they specifically address environmental and social needs, have a high economic impact, and involve a wide range of raw materials raising multiple technical issues. The paper presents an account of the bespoke tool developed for assessing the sustainability of transport noise reduction devices. Regulatory standards for noise reduction devices and the relevant sustainability assessment tools and procedures adopted worldwide were reviewed in order to produce a set of pertinent sustainability criteria and indicators for NRDs projects, which were reviewed and edited during a stakeholder engagement process. A decision making process for assessing the relative sustainability of noise reduction devices was formulated following the review of the literature. Two key stages were identified: (1) collection of data for criteria fulfillment evaluation and (2) multi-criteria analysis for assessing the sustainability of noise reduction devices. Appropriate tools and methods for achieving both objectives are recommended

    Comparative analysis of MCDM methods for the assessment of sustainable housing affordability

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    While affordability is traditionally assessed in economic terms, this paper tests a new assessment method that draws closer links with sustainability by considering economic, social and environmental criteria that impact on a household's quality of life. The paper presents an empirical application and comparison of six different multiple criteria decision making (MCDM) approaches for the purpose of assessing sustainable housing affordability.The comparative performance of the weighted product model (WPM), the weighted sum model (WSM), the revised AHP, TOPSIS and COPRAS, is investigated. The purpose of the comparative analysis is to determine how different MCDM methods compare when used for a sustainable housing affordability assessment model. 20 Evaluative criteria and 10 alternative are as in Liverpool, England, were considered. The applicability of different MCDM methods for the focused decision problem was investigated. The paper discusses the similarities in MCDM methods, evaluates their robustness and contrasts the resulting rankings
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