2,537 research outputs found

    Differences in endplate deformation of the adjacent and augmented vertebra following cement augmentation

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    Vertebral cement augmentation can restore the stiffness and strength of a fractured vertebra and relieve chronic pain. Previous finite element analysis, biomechanical tests and clinical studies have indirectly associated new adjacent vertebral fractures following augmentation to altered loading. The aim of this repeated measures in situ biomechanical study was to determine the changes in the adjacent and augmented endplate deformation following cement augmentation of human cadaveric functional spine units (FSU) using micro-computed tomography (micro-CT). The surrounding soft tissue and posterior elements of 22 cadaveric human FSU were removed. FSU were assigned to two groups, control (n=8) (loaded on day 1 and day 2) and augmented (n=14) (loaded on day 1, augmented 20% cement fill, and loaded on day 2). The augmented group was further subdivided into a prophylactic augmentation group (n=9), and vertebrae which spontaneously fractured during loading on day 1 (n=5). The FSU were axially loaded (200, 1,000, 1,500-2,000N) within a custom made radiolucent, saline filled loading device. At each loading step, FSUs were scanned using the micro-CT. Endplate heights were determined using custom software. No significant increase in endplate deformation following cement augmentation was noted for the adjacent endplate (P>0.05). The deformation of the augmented endplate was significantly reduced following cement augmentation for both the prophylactic and fracture group (P<0.05, P<0.01, respectively). Endplate deformation of the controls showed no statistically significant differences between loading on day 1 and day 2. A linear relationship was noted between the applied compressive load and endplate deflection (R 2=0.58). Evidence of significant endplate deformation differences between unaugmented and augmented FSU, while evident for the augmented endplate, was not present for the adjacent endplate. This non-invasive micro-CT method may also be useful to investigate endplate failure, and parameters that predict vertebral failur

    Ecophysiological traits of grasses: resolving the effects of photosynthetic pathway and phylogeny

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    C4 photosynthesis is an important example of convergent evolution in plants, having arisen in eudicots, monocots and diatoms. Comparisons between such diverse groups are confounded by phylogenetic and ecological differences, so that only broad generalisations can be made about the role of C4 photosynthesis in&#xd;&#xa;determining ecophysiological traits. However, 60% of C4 species occur in the grasses (Poaceae) and molecular phylogenetic techniques confirm that there are between 8 and 17 independent origins of C4 photosynthesis in the Poaceae. In a screening experiment, we compared leaf physiology and growth traits across several major&#xd;&#xa;independent C3 &#x26; C4 groups within the Poaceae, asking 1) which traits differ consistently between photosynthetic&#xd;&#xa;types and 2) which traits differ consistently between clades within each photosynthetic type

    Partitioning the components of Relative Growth Rate: how important is plant size variation?

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    Plant growth plays a key role in the functioning of the terrestrial biosphere, and there have been substantial efforts to understand why growth varies among species. To this end, a large number of experimental analyses have been undertaken; however, the emergent patterns between growth rate and its components are often contradictory. We believe that these conflicting results are a consequence of the way growth is measured. Growth is typically characterized by relative growth rate (RGR); however, RGR often declines as organisms get larger, making it difficult to compare species of different sizes. To overcome this problem, we advocate using nonlinear mixed-effects models so that RGR can be calculated at a standard size, and we present easily implemented methods for doing this. We then present new methods for analyzing the traditional components of RGR that explicitly allow for the fact that log (RGR) is the sum of its components. These methods provide an exact decomposition of the variance in log (RGR). Finally, we use simple analytical and simulation approaches to explore the effect of size variation on growth and its components and show that the relative importance of the components of RGR is influenced by the extent to which analyses standardize for plant size

    A more representative chamber: representation and the House of Lords

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    Since 1997 there has been substantive reform of the House of Lords in an effort to make the chamber ‘more democratic and more representative’. Whilst the Labour government failed to press ahead with any of the proposed plans for further reform following the removal of the bulk of the hereditary peers in 1999, it remained committed to the notion that such reform must make the second chamber ‘more representative’. The coalition government's programme advocates a long-term aspiration for a House wholly or mainly elected on the basis of proportional representation, and a short-term approach based on additional appointments to ensure a balance of the parties. What is clear in all of these proposals for reform is a desire for the House of Lords to become more representative than it is at present. However, what is less clear is what is meant by ‘representative’ – who the House of Lords is supposed to represent, and what form representation will take. Moreover, in proposing to make the chamber more representative, either through appointment or election, little attention has been paid to how the current House of Lords provides representation. This article examines these questions in the context of Pitkin's classic conceptions of representation and peers' attitudes towards their own representative rol

    "My job is to get pregnant women to the hospital": a qualitative study of the role of traditional birth attendants in the distribution of misoprostol to prevent post-partum haemorrhage in two provinces in Mozambique

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    © 2018 The Author(s). Background: Post-partum haemorrhage is the leading cause of maternal deaths in Mozambique. In 2015, the Mozambican Ministry of Health launched the National Strategy for the Prevention of Post-Partum Haemorrhage at the Community Level. The strategy included the distribution of misoprostol to women in advance at antenatal care and via Traditional Birth Attendants who directly administer the medication. The study explores the role of Traditional Birth Attendants in the misoprostol program and the views of women who used misoprostol to prevent post-partum haemorrhage. Methods: This descriptive study collected data through in-depth interviews and focus group discussions. Traditional Birth Attendants between the ages of 30-70 and women of reproductive age participated in the study. Data was collected between June-October 2017 in Inhambane and Nampula Provinces. Line by line thematic analysis was used to interpret the data using Nvivo (v.11). Results: The majority of TBAs in the study were satisfied with their role in the misoprostol program and were motivated to work with the formal health system to encourage women to access facility based births. Women who used misoprostol were also satisfied with the medication and encouraged family and friends to access it when needed. Women in the community and Traditional Birth Attendants requested assistance with transportation to reach the health facility to avoid home births. Conclusions: This study contributes to the evidence base that Traditional Birth Attendants are an appropriate channel for the distribution of misoprostol for the prevention of post-partum haemorrhage at the community level. More support and resources are needed to ensure Traditional Birth Attendants can assist women to have safe births when they are unable to reach the health facility. A consistent supply of misoprostol is needed to ensure women at the community level receive this life saving medication

    Toward a Framework for Outcome-Based Analytical Performance Specifications: A Methodology Review of Indirect Methods for Evaluating the Impact of Measurement Uncertainty on Clinical Outcomes

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    Background: For medical tests that have a central role in clinical decision-making, current guidelines advocate outcome-based analytical performance specifications. Given that empirical (clinical-trial style) analyses are often impractical or unfeasible in this context, the ability to set such specifications is expected to rely on indirect studies to calculate the impact of test measurement uncertainty on downstream clinical, operational and economic outcomes. Currently however, a lack of awareness and guidance concerning available alternative indirect methods is limiting the production of outcome-based specifications. Our aim therefore was to review available indirect methods and present an analytical framework to inform future outcome-based performance goals. Content: A methodology review consisting of database searches and extensive citation tracking was conducted to identify studies using indirect methods to incorporate or evaluate the impact of test measurement uncertainty on downstream outcomes (including clinical accuracy, clinical utility and/or costs). Eighty-two studies were identified, most of which evaluated the impact of imprecision and/or bias on clinical accuracy. A common analytical framework underpinning the various methods was identified, consisting of three key steps: (1) calculation of “true” test values; (2) calculation of measured test values (incorporating uncertainty); and (3) calculation of the impact of discrepancies between (1) and (2) on specified outcomes. A summary of the methods adopted is provided, and key considerations discussed. Conclusions: Various approaches are available for conducting indirect assessments to inform outcome-based performance specifications. This study provides an overview of methods and key considerations to inform future studies and research in this area

    Ion beam induced modification of exchange interaction and spin-orbit coupling in the Co2_2FeSi Heusler compound

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    A Co2_2FeSi (CFS) film with L21_1 structure was irradiated with different fluences of 30 keV Ga+^+ ions. Structural modifications were subsequently studied using the longitudinal (LMOKE) and quadratic (QMOKE) magneto-optical Kerr effect. Both the coercivity and the LMOKE amplitude were found to show a similar behavior upon irradiation: they are nearly constant up to ion fluences of 6×1015\approx6\times10^{15} ion/cm2^2, while they decrease with further increasing fluences and finally vanish at a fluence of 9×1016\approx9\times10^{16} ion/cm2^2, when the sample becomes paramagnetic. However, contrary to this behavior, the QMOKE signal nearly vanishes even for the smallest applied fluence of 3×10143\times10^{14} ion/cm2^2. We attribute this reduction of the QMOKE signal to an irradiation-induced degeneration of second or higher order spin-orbit coupling, which already happens at small fluences of 30 keV Ga+^+ ions. On the other hand, the reduction of coercivity and LMOKE signal with high ion fluences is probably caused by a reduction of the exchange interaction within the film material
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