367 research outputs found

    Comparison of landscape approaches to define spatial patterns of hillslope-scale sediment delivery ratio

    Get PDF
    A sediment delivery ratio (SDR) is that fraction of gross erosion that is transported from a given catchment in a given time interval. In essence, a SDR is a scaling factor that relates sediment availability and deposition at different spatial scales. In this paper, we focus on hillslope-scale SDR, i.e. the ratio of sediment produced from hillslopes to that delivered to the stream network. Factors that affect hillslope water movement, and thus entrainment or deposition of sediments, ultimately affecting the SDR, include upslope area, climate, topography, and soil cover. In erosion models, SDR is usually treated as a constant parameter. However, the use of spatially variable SDRs could improve the spatial prediction of the critical sources of sediment, i.e. identification of those areas directly affecting stream water quality. Such information would improve prioritisation of natural resource management effort and investment. Recent literature has described several landscape approaches to represent SDR variability in space, some of which account only for topography, whilst others consider topography and soil cover characteristics. The aim of this study was to evaluate four landscape approaches for their ability to depict spatial patterns of SDR in the Avon-Richardson catchment in the semi-arid Wimmera region (Victoria, South-east Australia). Erosion was assessed using a semi-distributed model (CatchMODS) with disaggregation based in subcatchments of around 40 km2 area. Hillslope gross erosion was assessed with a RUSLE approach. By applying the four landscape approaches using DEM and estimates of land use cover, four landscape index subcatchment distributions were calculated. These were normalised into standard distributions. Then, a sigmoid function was used to transform the standardised indices into SDR-index distributions ranging from zero to one. Finally, subcatchment SDRs were estimated as the product of the SDR-index by a whole-of-catchment SDR value that was estimated by calibration against sediment loads measured at five gauging stations of the study area. The major sources of hillslope erosion were modelled to be located in the southern hilly areas of the catchment. However, a topographic convergence approach predicted as well important contribution of hillslope-erosion sediment loads coming from the eastern flatter cropping land. The introduction of landscape-variable SDRs improved the overall goodness-of-fit of modelled versus observed sediment loads at five gauging stations located in the catchment for only the topographic convergence approach. However, the limited number of observations (11), the location of some gauging stations downstream of active gully erosion, and the lack of gauging stations monitoring the north-eastern part of the catchment hindered the assessment of which spatial distribution of hillslope erosion best represented the real catchment conditions. Further research is needed to define the relationship between landscape indices and SDR; and to evaluate the spatial distribution of erosion against more complete field evidence

    VPSIRR (Vulnerability - Pressure - State - Impact - Risk And Response): An Approach To Determine The Condition Of Estuaries And To Assess Where Management Responses Are

    Get PDF
    Estuaries are highly variable in terms of type and geomorphic classification. The condition of these systems is often a reflection of activities taking place in their catchments and the susceptibility of these systems to each particular pressure. Effective management intervention can be achieved when there is an understanding of the current condition of the estuary or component of the estuary and of the pressures likely to affect them. If this can be linked to the susceptibility of the estuary to the pressure (risk), the management activity can be prioritised. A framework based on the Pressure-State-Impact-Response model, but which also includes the vulnerability of the system to each of the pressures has been developed. A key feature of this framework is that the links between indicators of pressure, state and impact are clearly identified ensuring that only indicators relevant to the local situation are selected. In addition, a risk assessment process has been developed. This approach is called a VPSIRR (Vulnerability - Pressure - State - Impact - Risk - Response)approach. Application of this method increases the likelihood of being able to identify the causes of any observed changes in condition, making it easier to identify appropriate management actions. It also enables information to be provided to the community in a user-friendly manner. We have developed a user friendly computer package which enables the risk that each estuary is under from various pressures to be assessed and linked to condition. The package enables the certainty about various data used to inform the process, to be reported. Importantly, the package enables indicator information to be updated as better information becomes available. It also enables new indicator information to be incorporated into the software should better knowledge become available. This component would only be made available to software administrators. The package produces a colour coded and numeric report card comprising of 5 colours or numbers which is designed to be easily understood and interpreted by users from a variety of backgrounds. The software can be used to inform managers of where to focus management investment, but can also be used to educate people about natural resource issues and the implications of different catchment and estuary based activities. Fact sheets imbedded within the software provide details about the various indicators. These include how to collect data and where necessary, how to analyse them in order to use the software. The fact sheets also provide information on management responses to a variety of issues

    Systematic review and meta-analysis of risk of gestational diabetes in women with preconception mental disorders

    Get PDF
    There is a well-established bidirectional association between Type 2 diabetes and mental disorder and emerging evidence for an increased risk of perinatal mental disorder in women with gestational diabetes (GDM). However, the relation between mental disorder prior to pregnancy and subsequent risk of GDM remains relatively unexplored. This is a systematic review and meta-analysis of the risk of GDM in women with a range of preconception mental disorders. Peer-reviewed literature measuring odds of GDM and preconception mood, anxiety, psychotic and eating disorders was systematically reviewed. Risk of bias was assessed using a checklist. Two independent reviewers were involved. 22 observational studies met inclusion criteria; most were retrospective cohorts from English speaking, high income countries. 14 studies were at high risk of bias. There was evidence for an increased risk of GDM in women with schizophrenia (pooled OR 2.44; 95% CI 1.17,5.1; 5 studies) and a reduced risk of GDM in women with anorexia nervosa (pooled OR 0.63; 95% CI 0.49,0.80; 5 studies). There was some limited evidence of an increased risk in women with bipolar disorder. There was no evidence for an association with preconception depression or bulimia nervosa on meta-analysis. There were insufficient studies on anxiety disorders for meta-analysis. This review indicates that there is not a significant risk of GDM associated with many preconception mental disorders but women with psychotic disorders represent a group uniquely vulnerable to GDM. Early detection and management of GDM could improve physical and mental health outcomes for these women and their children

    Bone marrow lesions from osteoarthritis knees are characterized by sclerotic bone that is less well mineralized

    Get PDF
    INTRODUCTION. Although the presence of bone marrow lesions (BMLs) on magnetic resonance images is strongly associated with osteoarthritis progression and pain, the underlying pathology is not well established. The aim of the present study was to evaluate the architecture of subchondral bone in regions with and without BMLs from the same individual using bone histomorphometry. METHODS. Postmenopausal female subjects (n = 6, age 48 to 90 years) with predominantly medial compartment osteoarthritis and on a waiting list for total knee replacement were recruited. To identify the location of the BMLs, subjects had a magnetic resonance imaging scan performed on their study knee prior to total knee replacement using a GE 1.5 T scanner with a dedicated extremity coil. An axial map of the tibial plateau was made, delineating the precise location of the BML. After surgical removal of the tibial plateau, the BML was localized using the axial map from the magnetic resonance image and the lesion excised along with a comparably sized bone specimen adjacent to the BML and from the contralateral compartment without a BML. Cores were imaged via microcomputed tomography, and the bone volume fraction and tissue mineral density were calculated for each core. In addition, the thickness of the subchondral plate was measured, and the following quantitative metrics of trabecular structure were calculated for the subchondral trabecular bone in each core: trabecular number, thickness, and spacing, structure model index, connectivity density, and degree of anisotropy. We computed the mean and standard deviation for each parameter, and the unaffected bone from the medial tibial plateau and the bone from the lateral tibial plateau were compared with the affected BML region in the medial tibial plateau. RESULTS. Cores from the lesion area displayed increased bone volume fraction but reduced tissue mineral density. The samples from the subchondral trabecular lesion area exhibited increased trabecular thickness and were also markedly more plate-like than the bone in the other three locations, as evidenced by the lower value of the structural model index. Other differences in structure that were noted were increased trabecular spacing and a trend towards decreased trabecular number in the cores from the medial location as compared with the contralateral location. CONCLUSIONS. Our preliminary data localize specific changes in bone mineralization, remodeling and defects within BMLs features that are adjacent to the subchondral plate. These BMLs appear to be sclerotic compared with unaffected regions from the same individual based on the increased bone volume fraction and increased trabecular thickness. The mineral density in these lesions, however, is reduced and may render this area to be mechanically compromised, and thus susceptible to attrition.National Institutes of Health and National Institute of Arthritis and Musculoskeletal and Skin: Biomarkers in Osteoarthritis MRI Studies (U01 AR50900-02); AstraZenic

    The Children and Young People's Health Partnership Evelina London Model of Care: process evaluation protocol

    Get PDF
    Introduction Children and young people (CYP) in the UK have poor health outcomes, and there is increasing emergency department and hospital outpatient use. To address these problems in Lambeth and Southwark (two boroughs of London, UK), the local Clinical Commissioning Groups, Local Authorities and Healthcare Providers formed The Children and Young People’s Health Partnership (CYPHP), a clinical-academic programme for improving child health. The Partnership has developed the CYPHP Evelina London model, an integrated healthcare model that aims to deliver effective, coordinated care in primary and community settings and promote better self-management to over approximately 90 000 CYP in Lambeth and Southwark. This protocol is for the process evaluation of this model of care. Methods and analysis Alongside an impact evaluation, an in-depth, mixed-methods process evaluation will be used to understand the barriers and facilitators to implementing the model of care. The data collected mapped onto a logic model of how CYPHP is expected to improve child health outcomes. Data collection and analysis include qualitative interviews and focus groups with stakeholders, a policy review and a quantitative analysis of routine clinical and administrative data and questionnaire data. Information relating to the context of the trial that may affect implementation and/or outcomes of the CYPHP model of care will be documented. Ethics and dissemination The study has been reviewed by NHS REC Cornwall & Plymouth (17/SW/0275). The findings of this process evaluation will guide the scaling up and implementation of the CYPHP Evelina London Model of Care across the UK. Findings will be disseminated through publications and conferences, and implementation manuals and guidance for others working to improve child health through strengthening health systems. Trial registration number NCT03461848

    Drug use among British Bangladeshis in London: a macro-structural perspective focusing on disadvantages contributing to individuals’ drug use trajectories and engagement with treatment services

    Get PDF
    Aims: The main aim of our study was to produce an understanding of factors contributing to drug-using trajectories among men and women from a Bangladeshi background living in East London. Methods: Fifteen semi-structured, one-to-one interviews were conducted with male and female Bangladeshi drug users accessing treatment services. A macro-structural lens was adopted to interpret participants’ accounts of their drug use and explored the intersecting factors that at a micro, meso, and macro level impacted on their drug-using trajectories. Findings: Problem drug use (heroin and crack cocaine) among participants was the result of inter-related factors such as their friendship networks and the embeddedness of drugs in drug-using networks, the structural disadvantages participants experienced, and the need for concealment of their drug use which impacted on participants’ effective utilisation of drug treatment services. Problem drug use was a functional way of responding to and dealing with social, economic, and cultural disconnection from mainstream institutions as participants faced severe multiple disadvantages engendering stigma and shame. Conclusions: We propose a ‘life-focused’ intervention aimed at creating extra opportunities and making critically-needed resources available in the marginalised environment of the study’s participants, which are key to restoring and maintaining agency and sustaining well-being
    • 

    corecore