400 research outputs found

    Direction for the Future - Successive Acceleration of Positive and Negative Ions Applied to Space Propulsion

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    Electrical space thrusters show important advantages for applications in outer space compared to chemical thrusters, as they allow a longer mission lifetime with lower weight and propellant consumption. Mature technologies on the market today accelerate positive ions to generate thrust. The ion beam is neutralized by electrons downstream, and this need for an additional neutralization system has some drawbacks related to stability, lifetime and total weight and power consumption. Many new concepts, to get rid of the neutralizer, have been proposed, and the PEGASES ion-ion thruster is one of them. This new thruster concept aims at accelerating both positive and negative ions to generate thrust, such that additional neutralization is redundant. This chapter gives an overview of the concept of electric propulsion and the state of the development of this new ion-ion thruster.Comment: 10 pages, contribution to the CAS-CERN Accelerator School: Ion Sources, Senec, Slovakia, 29 May - 8 June 2012, edited by R. Bailey. appears in CERN Yellow Report CERN-2013-007, pp.575-58

    Thermogravimetric analysis of carbon black and engine soot - Towards a more robust oil analysis method

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    This work examined the thermal behaviour of diesel engine produced soot and commercial carbon black using thermogravimetric analysis (TGA). It was found that during TGA analysis of the carbon matrices (at a temperature range commonly used for soot-in-oil content determination), a gradual mass loss occurred. This was attributed to pyrolysis effects and combustion processes occurring due to poor hydrodynamic design of some commercial thermobalances. This process resulted in a significant mass loss of the carbon during TGA. This finding may strongly effect soot-in-oil analysis conducted using current methods. Experiments were conducted using a range of soot-in-oil mixtures according to the widely used thermogravimetric standard method ASTM 5967-08 which showed a significant underestimation of the soot content in the oil as a result of carbon mass loss due to combustion and/or pyrolysis effects. An improved oil analysis method is proposed which provides a significantly increased accuracy of soot determination in lubricant oils

    Forest type affects the capacity of Amazonian tree species to store carbon as woody biomass

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    For tropical tree species, wood density can vary greatly both within and between species depending on environmental conditions. In Amazonian seasonally flooded forests, yearly flood pulses influence tree growth and floodplain trees have developed specialised strategies to cope with prolonged submersion during flooding. We therefore hypothesised that seasonal floods significantly affect the capacity of trees to store carbon as woody biomass per unit volume and that forest hydrology would be an important factor in determining above-ground woody biomass and carbon stocks across the Amazon Basin. To test these hypotheses, we collected and analysed wood cores from 44 species occurring in both seasonally flooded (várzea) forests and adjacent unflooded (terra firme) forests along the Juruá River, western Brazilian Amazon. We used wood specific gravity (WSG) as a proxy of woody biomass and carbon. We compared WSG values within species, genera and families and found higher WSG in unflooded forest trees compared to their conspecifics in seasonally flooded várzea. Moreover, the effect of forest type on WSG was strongest at the family level and weakest at the species level. We further assessed the implications of WSG accuracy on above-ground woody tree biomass and found significant differences in AGWB as a function of WSG. Again, the differences became greater with lower taxonomic specificity, but also increased with lower site-specificity and greater tree dimensions. In conclusion, habitat specific WSG is important to quantify and map the spatial distribution of above-ground woody biomass and carbon in Amazonian forests

    A Dynamic Knowledge Management Framework for the High Value Manufacturing Industry

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    Dynamic Knowledge Management (KM) is a combination of cultural and technological factors, including the cultural factors of people and their motivations, technological factors of content and infrastructure and, where these both come together, interface factors. In this paper a Dynamic KM framework is described in the context of employees being motivated to create profit for their company through product development in high value manufacturing. It is reported how the framework was discussed during a meeting of the collaborating company’s (BAE Systems) project stakeholders. Participants agreed the framework would have most benefit at the start of the product lifecycle before key decisions were made. The framework has been designed to support organisational learning and to reward employees that improve the position of the company in the market place

    Institutional stakeholders’ views on jaguar conservation issues in central Brazil

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    AbstractLarge carnivore management is typically a source of heated controversy worldwide and, in the Americas, jaguars (Panthera onca) are at the centre of many human–wildlife conflicts. Although findings suggest that social, rather than economic, factors are important reasons for why humans kill jaguars, few studies focus on stakeholder attitudes towards jaguar conservation beyond quantifying livestock depredation. Yet insights from other large carnivore conflicts demonstrate the importance of the political landscape and stakeholder attitudes in carnivore conservation. To explore the extent to which stakeholder views about jaguar conservation aligned with institutional arrangements, we conducted a stakeholder analysis among personnel working for key institutions in central Brazil. Using Q methodology, we identified three stakeholder perspectives focusing on: A) jaguars’ intrinsic right to exist; B) wider ecocentric values; and C) contesting jaguar-focused conservation. The three institutional stakeholder groups all accepted the jaguar’s fundamental right to exist and agreed that it was important to establish protected areas for jaguars. Yet, institutional stakeholder views diverged regarding the desired distribution of jaguars in Brazil, hunting policies, and the effects of hunting and development projects on jaguar conservation. These differences and their underlying motivations are important to consider for successful jaguar conservation strategies in Brazil

    Impact of the Covid-19 Pandemic on ALS Care in the UK

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    The Covid-19 pandemic has impacted healthcare. Our aim was to identify how amyotrophic lateral sclerosis (ALS) care in the UK has been affected by the pandemic by exploring the experiences of people living with ALS (plwALS), healthcare professionals (HCPs) working with plwALS, and ALS care centers. Three surveys were carried out to explore the experiences of plwALS, HCPs and ALS care centers during the pandemic. Quantitative data were analyzed using descriptive and inferential statistics and triangulated with the qualitative data which were analyzed thematically. Responses from 53 plwALS, 73 HCPs and 23 ALS care centers were analyzed. Five main themes were identified: keeping safe, losses, negative emotions, delivering care and alternative care delivery in a pandemic. PlwALS and HCPs felt that care was sub-optimal as a result of the pandemic. Changes to care included longer waiting times and face-to-face appointments being canceled or replaced by virtual consultations. While benefits of virtual consultations were reported, concerns were raised about incomplete clinical assessments and the disruption of provision of testing and interventions. ALS care has changed as a result of the pandemic. Patients have had a lack of face-to-face contact with HCPs and have experienced delays to investigations and treatments. PlwALS and HCPs were concerned about the impact of this change, but the long-term implications remain unclear. We propose recommendations for HCPs caring for plwALS, that will promote continuity of evidenced based care in the context of a pandemic

    Structure and Composition of Terra Firme and Seasonally Flooded Várzea Forests in the Western Brazilian Amazon

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    Research Highlights: Rare, or sparsely distributed, species drive the floristic diversity of upland, terra firme and seasonally flooded forests in the central Juruá—a remote and hitherto floristically poorly known area in the Brazilian Amazon. Background and Objectives: Floristic inventories are critical for modelling and understanding the role of Amazonian forests in climate regulation, for sustainable management of forest resources and efficient conservation planning. Yet, detailed information about the often complex spatial distributions of many Amazonian woody plants is limited. Here, we provide information about forest structure and species composition from a remote terra firme forest and an adjacent floodplain forest in the western Brazilian Amazon. More specifically, we ask (1) how floristically different are the terra firme and floodplain forests? and (2) how variable is species composition within the same forest type? Materials and Methods: Between September 2016 and October 2017, we inventoried 97 plots (each 0.1 ha; 100 × 10 m) placed at least 800 m apart, with 46 plots in terra firme forest and 51 in seasonally flooded forest. We included all trees, hemi-epiphytes and palms with diameter at breast height (dbh) > 10 cm and woody lianas > 5 cm dbh. We examine forest structure, family- and species-level floristic composition and species diversity within and between forest types using family and species importance values, rarefaction curves and dissimilarity matrices. Results: Terra firme forest and seasonally flooded forest woody plant communities differ both in structure and species composition, which was highly variable within forest types. Many species were shared between terra firme and seasonally flooded forests, but most species were forest type-specific. Whereas species richness was greatest in the terra firme forest, floodplain species richness was among the highest regionally. Conclusions: Floodplain forests are a crucial complement to terra firme forests in terms of Amazonian woody plant diversity

    The effect of increasing physical activity and/or omega-3 supplementation on fatigue in inflammatory bowel disease

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    Objective: Fatigue is frequently reported by patients with inflammatory bowel disease (IBD), irrespective of disease activity; however, evidence regarding fatigue management is limited. This study tested the effect of individualised advice to increase physical activity and/or omega-3 fatty acids supplementation, on IBD-related fatigue. Methods: A pilot study in patients with inactive IBD, utilising a randomised controlled 2x2 factorial design (four groups) compared baseline and post-intervention fatigque scores. Study interventions: individualised exercise advice (15 minute consultation) and/or supplementation (omega-3 fatty acids, 2970mg/day) for 12 weeks. Control interventions: general health discussion and/or placebo supplement. All patients received follow-up support. Primary outcome was fatigue measured by Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale score; secondary outcomes included change in Inflammatory Bowel Disease-Fatigue (IBD-F) scale score. Results: From n=656 screened patients, n=74 who met the selection criteria were randomised, n=60 commenced, and n=52 completed the study. Fatigue as tThe primary outcome fatigque, measured with FACIT-F, showed slight worsening in the omega-3 supplementation group (95%CI:-8.6-(-0.7);p=0.02), and no change in the exercise advice group (p=0.38). Reduced fatigue, measured by IBD-F score, was identified in the exercise group (95%CI:-3.8-(-0.2);p=0.03). One treatment-related adverse event (musculoskeletal pain) was reported with exercise. Conclusions: Advice to increase physical activity and omega-3 supplementation, singly or in combination, were shown to be safe and generally well-tolerated. There was no evidence of exercise-related adverse effects on gut-related symptoms, and some evidence of improvement in fatigue. The slight worsening of fatigue with omega-3 supplementation is unexplained. Regular moderate to -vigorous exercise may be a self-management option in IBD-related fatigue

    Physical activity and quality of life in cancer 3 survivors: A meta-synthesis of qualitative research

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    Qualitative research on the impact of physical activity on quality of life (QoL) in adults diagnosed with cancer is accumulating. However, the fields of physical activity and cancer survivorship lack a synthesis of this research to reliably understand the implications for future research and practice. The aim of this meta-synthesis was to identify, appraise, and synthesize qualitative research on cancer survivors’ perspectives of the impact of physical activity on their QoL. Seven electronic databases were searched for original studies published in English, and reference lists of relevant studies were hand-searched to identify additional studies. Forty studies met eligibility criteria and were included in this meta-synthesis. Study characteristics and major findings were extracted, and findings were summarized, compared, and synthesized. Themes identified in this review revealed that physical activity positively impacted four dimensions of cancer survivors’ QoL: physical (e.g., managing the physical consequences of cancer and its treatment), psychological (e.g., evoking positive self-perceptions), social (e.g., feeling understood by others), and spiritual (e.g.,redefining life purpose). This meta-synthesis corroborates conclusions resulting from the synthesis of quantitative research and illustrates that physical activity can be used to improve QoL in adult cancer survivors, regardless of type of diagnosis (i.e., stage, cancer type) and treatment status. It also provides insight into which specific aspects within each dimension of QoL were impacted by physical activity from cancer survivors’ perspectives, which is important for understanding the meaning and utility of physical activity for them. However, more work remains to further develop the qualitative evidence base to better understand how physical activity impacts QoL in men, younger survivors, and those diagnosed with less common types of cancer at different points along cancer trajectory (i.e., diagnosis, treatment, post-treatment, palliation)
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