7,566 research outputs found

    Optimizing Echo State Networks for Static Pattern Recognition

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    Static pattern recognition requires a machine to classify an object on the basis of a combination of attributes and is typically performed using machine learning techniques such as support vector machines and multilayer perceptrons. Unusually, in this study, we applied a successful time-series processing neural network architecture, the echo state network (ESN), to a static pattern recognition task. The networks were presented with clamped input data patterns, but in this work, they were allowed to run until their output units delivered a stable set of output activations, in a similar fashion to previous work that focused on the behaviour of ESN reservoir units. Our aim was to see if the short-term memory developed by the reservoir and the clamped inputs could deliver improved overall classification accuracy. The study utilized a challenging, high dimensional, real-world plant species spectroradiometry classification dataset with the objective of accurately detecting one of the world’s top 100 invasive plant species. Surprisingly, the ESNs performed equally well with both unsettled and settled reservoirs. Delivering a classification accuracy of 96.60%, the clamped ESNs outperformed three widely used machine learning techniques, namely support vector machines, extreme learning machines and multilayer perceptrons. Contrary to past work, where inputs were clamped until reservoir stabilization, it was found that it was possible to obtain similar classification accuracy (96.49%) by clamping the input patterns for just two repeats. The chief contribution of this work is that a recurrent architecture can get good classification accuracy, even while the reservoir is still in an unstable state

    The Structural Sources of Socioeconomic Inequalities in Health: A Cross-National Perspective

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    This article investigates how macro-level structures condition the sources of socioeconomic inequalities in health. Drawing on multiple social science disciplines, the authors develop theoretically grounded propositions about how different types of welfare states, varieties of capitalism, and social structures give rise to cross-national variations in the sources of health inequalities. They consider how these macro-level structures affect the distribution of five key resources important to health, estimate the relative contribution that each resource makes to health inequalities, and compare those contributions in 21 developed democracies. Moving beyond a current literature focused on welfare states, the authors show how different types of political economies and social structures also condition the health gradient. This research carries implications for policy and suggests agendas for further investigation into the relationship between macro-level structures and inequalities in health

    Movement patterns and athletic performance of leopards in the Okavango Delta

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    Although leopards are the most widespread of all the big cats and are known for their adaptability, they are elusive and little is known in detail about their movement and hunting energetics. We used high-resolution GPS/IMU (inertial measurement unit) collars to record position, activity and the first high-speed movement data on four male leopards in the Okavango Delta, an area with high habitat diversity and habitat fragmentation. Leopards in this study were generally active and conducted more runs during the night, with peaks in activity and number of runs in the morning and evening twilight. Runs were generally short (less than 100 m) and relatively slow (maximum speed 5.3 m s−1, mean of individual medians) compared to other large predators. Average daily travel distance was 11 km and maximum daily travel distance was 29 km. No direct correlation was found between average daily temperature and travel distance or between season and travel distance. Total daily energy requirements based on locomotor cost and basal metabolic rate varied little between individuals and over time. This study provides novel insights into movement patterns and athletic performance of leopards through quantitative high-resolution measurement of the locomotor, energetic, spatial and temporal movement characteristics. The results are unbiased by methodological and observational limitations characteristic of previous studies and demonstrate the utility of applying new technologies to field studies of elusive nocturnal species

    Gap junction proteins and their role in spinal cord injury

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    © 2015 Tonkin, Mao, O'Carroll, Nicholson, Green, Gorrie and Moalem-Taylor. Gap junctions are specialized intercellular communication channels that are formed by two hexameric connexin hemichannels, one provided by each of the two adjacent cells. Gap junctions and hemichannels play an important role in regulating cellular metabolism, signaling, and functions in both normal and pathological conditions. Following spinal cord injury (SCI), there is damage and disturbance to the neuronal elements of the spinal cord including severing of axon tracts and rapid cell death. The initial mechanical disruption is followed by multiple secondary cascades that cause further tissue loss and dysfunction. Recent studies have implicated connexin proteins as playing a critical role in the secondary phase of SCI by propagating death signals through extensive glial networks. In this review, we bring together past and current studies to outline the distribution, changes and roles of various connexins found in neurons and glial cells, before and in response to SCI. We discuss the contribution of pathologically activated connexin proteins, in particular connexin 43, to functional recovery and neuropathic pain, as well as providing an update on potential connexin specific pharmacological agents to treat SCI

    Health technology assessment of medical devices: a survey of non-European union agencies.

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    PublishedJournal ArticleResearch Support, Non-U.S. Gov'tThis is the final version of the article. Available from Cambridge University Press via the DOI in this record.OBJECTIVES: The aim of this study was to review and compare current health technology assessment (HTA) activities for medical devices across non-European Union HTA agencies. METHODS: HTA activities for medical devices were evaluated from three perspectives: organizational structure, processes, and methods. Agencies were primarily selected upon membership of existing HTA networks. The data collection was performed in two stages: stage 1-agency Web-site assessment using a standardized questionnaire, followed by review and validation of the collected data by a representative of the agency; and stage 2-semi-structured telephone interviews with key informants of a sub-sample of agencies. RESULTS: In total, thirty-six HTA agencies across twenty non-EU countries assessing medical devices were included. Twenty-seven of thirty-six (75 percent) agencies were judged at stage 1 to have adopted HTA-specific approaches for medical devices (MD-specific agencies) that were largely organizational or procedural. There appeared to be few differences in the organization, process and methods between MD-specific and non-MD-specific agencies. Although the majority (69 percent) of both categories of agency had specific methods guidance or policy for evidence submission, only one MD-specific agency had developed methodological guidelines specific to medical devices. In stage 2, many MD-specific agencies cited insufficient resources (budget, skilled employees), lack of coordination (between regulator and reimbursement bodies), and the inability to generalize findings from evidence synthesis to be key challenges in the HTA of medical devices. CONCLUSIONS: The lack of evidence for differentiation in scientific methods for HTA of devices raises the question of whether HTA needs to develop new methods for medical devices but rather adapt existing methodological approaches. In contrast, organizational and/or procedural adaptation of existing HTA agency frameworks to accommodate medical devices appear relatively commonplace.This study was supported by a research grant from the European Community’s Seventh Framework Program (FP7 - HEALTH Grant Agreement no. 305694). The sponsor had no role in the study design, collection and analysis of data, writing of the report, or submission of the paper for publication. The authors wish to thank all interviewees and agencies’ assessment forms verifiers for their invaluable contribution to the completion of this study

    The discovery of a novel antibiotic for the treatment of Clostridium difficile infections: a story of an effective academic-industrial partnership

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    Academic drug discovery is playing an increasingly important role in the identification of new therapies for a wide range of diseases. There is no one model that guarantees success. We describe here a drug discovery story where chance, the ability to capitalise on chance, and the assembling of a range of expertise, have all played important roles in the discovery and subsequent development of an antibiotic chemotype based on the bis-benzimidazole scaffold, with potency against a number of current therapeutically challenging diseases. One compound in this class, SMT19969, has recently entered Phase 2 human clinical trials for the treatment of Clostridium difficile infections

    Additive opportunistic capture explains group hunting benefits in African wild dogs

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    African wild dogs (Lycaon pictus) are described as highly collaborative endurance pursuit hunters based on observations derived primarily from the grass plains of East Africa. However, the remaining population of this endangered species mainly occupies mixed woodland savannah where hunting strategies appear to differ from those previously described. We used high-resolution GPS and inertial technology to record fine-scale movement of all members of a single pack of six adult African wild dogs in northern Botswana. The dogs used multiple short-distance hunting attempts with a low individual kill rate (15.5%), but high group feeding rate due to the sharing of prey. Use of high-level cooperative chase strategies (coordination and collaboration) was not recorded. In the mixed woodland habitats typical of their current range, simultaneous, opportunistic, short-distance chasing by dogs pursuing multiple prey (rather than long collaborative pursuits of single prey by multiple individuals) could be the key to their relative success in these habitats

    Sclerosing epithelioid fibrosarcoma as a rare cause of ascites in a young man: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>Sclerosing epithelioid fibrosarcoma is a rare but distinct variant of fibrosarcoma that not only presents as a deep-seated mass on the limbs and neck but can also occur adjacent to the fascia or peritoneum, as well as the trunk and spine. We report the case of an intra-abdominal sclerosing epithelioid fibrosarcoma, which to best of the authors' knowledge has not been described previously. The patient discussed here developed lung metastases but is still alive 1-year post-diagnosis.</p> <p>Case presentation</p> <p>A 29-year-old man presented with a 2-week history of progressive abdominal distension and pain and was found to have marked ascites. A full liver screen was unremarkable with abdominal and chest computed tomography scans only confirming ascites. After a diagnostic laparotomy, biopsies were taken from the greater omentum and peritoneal nodules. Histopathology revealed a malignant tumour composed of sheets and cords of small round cells set in collagenized stroma. After further molecular investigation at the Mayo Clinic, USA, the diagnosis of a high-grade sclerosing epithelioid fibrosarcoma was confirmed.</p> <p>Conclusion</p> <p>Sclerosing epithelioid fibrosarcoma is an extremely rare tumour, which is often difficult to diagnose and which few pathologists have encountered. This case is particularly unusual because of the intra-abdominal origin of the tumour. Owing to the rarity of sclerosing epithelioid fibrosarcoma, there is no clear evidence regarding the prognosis of such a tumour, although sclerosing epithelioid fibrosarcoma is able to metastasize many years post-presentation. It is important that physicians and pathologists are aware of this unusual tumour.</p
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