2,809 research outputs found

    The future stability of upland blanket peat following historical erosion and recent re-vegetation

    Get PDF
    The importance of fluvial dissection in upland blanket peat erosion is well-established but knowledge of the significance of peatland gully system development is limited. This thesis investigates the stability of upland blanket peat in relation to recent re-vegetation and historical erosion of peatland gully systems. It combines regional morphological surveys in a GIS framework with detailed field and laboratory analyses. Detailed research was carried out at three study areas across Northern England: The Cheviot (Northumberland), Moor House (North Pennines) and Wessenden Head Moss (Southern Pennines). A regional-scale investigation into gully development at the three sites demonstrated that the end members (Type 1 and Type 2 dissection) in Bower's 1960 classification of dissection types could be identified but a revised dissection classification including a third category of anastomosing dissection was needed. Regional variations in erosion and gully form were observed. The most extensive aerial erosion was on The Cheviot (80 %) and least at Moor House (48 %). Re-vegetation was most well-established at Moor House (80 % of the eroded peat) and least on Wessenden Head Moss (45 % of the eroded peat). The local topography of each site was the key in explaining erosion patterns. Linear dissection dominated on steeply sloping ground and anastomosing dissection on gentle sloping summit areas. Dendritic dissection occurred on intermediate slopes. Approximate slope angles for the dentritic transitional zone vary in relation to the local topography; however, the means for the three study sites are 3.7 (Moor House), 4.9 (The Cheviot) and 1.4 (Wessenden Head Moss).Local-scale variations in erosion were observed on the interfluves and within existing gully systems. On the interfluves peat accumulation rates were estimated from Spheroidal Carbonaceous Particle deposition. Average rates were 0.5 mm yr(^-1) under moorland grass and 1.2 mm yr(^-1) under heather. Erosion potential of these sites was estimated from rainfall simulation experiments. The potential for erosion was high (243 t km(^-2), 0.243 mm yr(^-1)), though not atypical of local directly measured erosion rates. However, experimental results showed that sediment production rarely occurred below a rainfall intensity of 12 mm hr(^-1) (high intensity for the Pennines) and with a presence of an intact vegetation cover sediment is only locally entrained and re-deposited and actual erosion under current climatic conditions is likely to be low. The onset of peat erosion was estimated by comparing eroded and uneroded cores. It is thought the most recent phase of erosion resulted from climatic change and land management and occurred some 570 years ago on Wessenden Head Moss and between 300 - 330 years ago at Moor House and on The Cheviot. Over the last approximate 50- years, infilling and re-vegetation of the bases of gully systems has been observed. The peat within the gully stratigraphy appears to be eroded, re-deposited or grown in situ. The future of upland blanket peat will likely involve further stabilisation of the gully systems; however, in severely eroded areas where the peat is totally stripped and surface hydrological regime destroyed, the peat will not recover

    Horizontal transfer of OC1 transposons in the Tasmanian devil

    Get PDF
    BACKGROUND There is growing recognition that horizontal DNA transfer, a process known to be common in prokaryotes, is also a significant source of genomic variation in eukaryotes. Horizontal transfer of transposable elements (HTT) may be especially prevalent in eukaryotes given the inherent mobility, widespread occurrence, and prolific abundance of these elements in many eukaryotic genomes. RESULTS Here, we provide evidence for a new case of HTT of the transposon family OposCharlie1 (OC1) in the Tasmanian devil, Sarcophilus harrisii. Bioinformatic analyses of OC1 sequences in the Tasmanian devil genome suggest that this transposon infiltrated the common ancestor of the Dasyuridae family ~17 million years ago. This estimate is corroborated by a PCR-based screen for the presence/absence of this family in Tasmanian devils and closely-related species. CONCLUSIONS This case of HTT is the first to be reported in dasyurids. It brings the number of animal lineages independently invaded by OC1 to 12, and adds a fourth continent to the pandemic-like pattern of invasion of this transposon. In the context of these data, we discuss the evolutionary history of this transposon family and its potential impact on the diversification of marsupials.The authors would like to acknowledge the following organizations for funding portions of this work: NIH-R01 GM077582 (CF), M.J. Murdock Charitable Trust (SS) and NSF-MCB-1150213 (SS

    CATTLE FEEDER PERCEPTIONS OF LIVESTOCK MANDATORY PRICE REPORTING

    Get PDF
    Because of the significant investment in the mandatory price reporting program (MPR) by the USDA and by packers, it is important to understand what producers believe about its effectiveness. This study reports results from a survey of feedyards located primarily in Kansas, Nebraska, Texas, and Iowa. Results indicate a diversity of opinion regarding MPR effectiveness. On average producers are neutral to negative regarding the value of MPR to them. Interestingly, feedlot characteristics appear to have little systematic relationship to the manager's perceptions regarding the usefulness of MPR.Livestock Production/Industries,

    Women's Occupational Choice and Entry into Male-Dominated Occupations

    Get PDF
    The research presented here is in investigation into women's occupational choice with specific reference to women in male-dominated occupations. Three main research areas are reviewed and evaluated: theories of occupational choice in general; theories of women's occupational choice; and theories pertaining to women's choice of and experiences in male-dominated occupations. An exploratory study was carried out into the gender-dominant occupational preferences of female and male students, using the theoretical framework of Bandura's self-efficacy theory. The main finding of this Study was that self-efficacy expectations do not play a large part in explaining women's and men’s preference for gender-typical occupations and reluctance to consider gender-atypical occupations. The main study takes a more global approach and investigates a large number of possible psychological and social determinants of women's occupational choice and entry into male-dominated occupations. The subjects in this piece of research were women employed in three types of male-dominated occupation : manual, non-manual; and transitional (occupations that are changing from male-domination to gender-neutrality). A group of women in non-manual female-dominated occupations was also included as a control group. The subjects participated in individual, semi-structured interviews and completed three questionnaires. The resulting data was subjected to both quantitative and qualitative analyses. Many diverse elements were found to influence women’s occupational choice. Differences between women in different types of male-dominated occupation, In the antecedents to their entry into a male-dominated job and in then- experiences at work, are discussed. A model representing women's occupational choice, with particular reference to women in male-dominated occupations, is proposed. Next the factors determining women's experiences in male-dominated areas of work are delineated. Finally suggestions for future research are put forward, and conclusions are drawn

    Rethinking Urban Nature: The Rise and Value of Nature-Based Solutions (NBS) in Europe

    Get PDF
    Nature-Based Solutions (NBS) have been proposed by the European Union as the most contemporary approach to delivering resilient cities in Europe. Through official guidance and funded projects, the Horizon 2020 programme, the EU has positioned nature at the centre of landscape and urban planning debates. However, there remains a scepticism regarding whether the support of NBS as an alternative to green infrastructure (GI) planning is meaningful and appropriate or damaging to existing practices. Furthermore, the framing of NBS does not, to date, extend the conceptual, practical or political parameters of ‘green space’ planning beyond terminological changes. Its most significant contribution to urban planning is the emphasis it places on urban ecology as a foundational principle of all development. To assess the added value of NBS in the planning and management of urban landscapes the paper reflects on the academic discussions surrounding the approach. This examines how NBS are being used to shape support for investment in urban nature but also argues that it potentially creates a schism between advocates of existing green space terminology and approaches. It concludes by setting the parameters for further analysis of how NBS are being, and may be used, going forward to socio-economic and ecological agendas in the EU

    Novel Solutions or Rebranded Approaches: Evaluating the use of Nature-Based Solutions (NBS) in Europe

    Get PDF
    The Nature-Based Solutions (NBS) concept is the most recent entry to discussions around how “nature” can be mobilized to render urban areas more resilient to the threat of climate change. The concept has been championed by the European Commission (EC) as a tool that can transform contemporary environmental, social and economic challenges into opportunities for innovation, bolstering Europe's position as a leader in climate change mitigation and adaptation. With its current research and innovation programme—Horizon 2020—the EC looks to position itself as the global NBS frontrunner, providing funding to cities to act as NBS demonstrator projects across the continent. These are expected to provide best-practice examples that can be replicated globally. This paper focuses on three Horizon 2020-funded NBS demonstrator projects: Connecting Nature, URBAN GreenUP and Grow Green, each of which brings together a suite of urban partners from both within and outside the European Union (EU). It examines the internal “politics” i.e., the aims and internal governance and implementation issues associated with these projects, and analyses how partners perceive the NBS concept. To engage with these aims, interviews were conducted with a diverse set of NBS “practitioners” working within the three projects. Analysis showed that the projects aim to influence climate-change resilient and sustainable urbanism through the process of retrofitting cities with small-scale green and blue interventions, as well as help the EU secure stronger diplomatic relations with neighboring non-EU countries and key international trade partners. It also illustrated that for many project partners, NBS is perceived to be a novel concept, because it re-frames pre-existing terms such as Green and Blue Infrastructure (GBI) and Ecosystem Services (ES) in a way that makes principles of urban greening more understandable to lay audiences and more politically palatable for urban governments. However, partners also warn that this framing of NBS has led to a narrow and idealized representation of nature; one that simultaneously undervalues biodiversity and oversells the capacity of natural processes to provide “solutions” to urban climate vulnerability and broader patterns of unsustainable urbanism.</jats:p

    Evaluating Digital Scholarship: Suggestions and Strategies for the Text Encoding Initiative

    Get PDF
    As part of a larger pilot study on the evaluation of digital scholarship, we consider what role, if any, the TEI Consortium and user community might play in evaluating scholarship that utilize the TEI tag set. Our rationale for focusing on the role of the TEI Consortium in the discussion of evaluation is twofold. First, the TEI Guidelines represents an encoding standard for texts that is supported by a large community actively interested in the application and development of these standards. Second, feedback concerning evaluation criteria for digital scholarship has not been explicitly gathered from the TEI community and may provide additional understanding of the value, process, and assessment of text encoding. Determining what to evaluate and how to do so reveals the community’s definitions of scholarship in general. The clarification and articulation of evaluation criteria, therefore, remains a high priority as digital scholarship continues to develop

    Deposition on fibrous filters in the interception region

    Get PDF
    When deposit accumulates inside a fibrous filter the fluid flow through the filter, and hence the filters collection efficiency, is altered. Although this is well known, it is difficult to model the particle build up within a filter. However it is crucial that a full understanding of the process of particle deposition and its effects upon further deposition is obtained in order to understand the performances of fibrous filters. We have been developing a numerical model of fibrous filtration aimed at investigating deposition due to various mechanisms and the effect filter properties and particle characteristics have upon it (Dunnett and Clement 2006, 2009). We have shown that, for small particles where the dominant mechanism by which particles deposit is diffusion, the porosity of the deposit formed does not significantly influence further deposition. For larger particles the porosity of the deposit has been seen to have a greater influence upon the flow field, and hence upon particle behaviour. In this paper we consider particles for which interception is the main mechanism of deposition

    Numerical investigation into the loading behaviour of filters operating in the diffusional and interception deposition regimes

    Get PDF
    Using a previously developed theory, which allows for changes in gas flow from deposit growth, calculations are performed for deposition on an initially cylindrical fibre. The deposit is given a specified porosity through which the flow is calculated from Darcy's equation using the Beavers and Joseph (1967) boundary condition at the outer boundary. Results are obtained for different porosities φ the volume fraction of space in the deposit, for flow conditions such that deposition occurs by the mechanisms of diffusion and interception, but not impaction (Stk1 and interception dominates, deposition increases with increase in φ and is significant for φ ≥0.9 where more streamlines pass through the deposit. The shape of the deposit remains peaked at the front of the fibre, at the forward stagnation point, but, if a deposit has an initial flat front, it grows into a shape peaked away from the stagnation point, as observed by Kanaoka et al. (1986). Possible reasons for this behaviour are discussed
    corecore