531 research outputs found

    Carbon source-sink limitations differ between two Species with Contrasting Growth Strategies.

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    Understanding how carbon source and sink strengths limit plant growth is a critical knowledge gap that hinders efforts to maximise crop yield. We investigated how differences in growth rate arise from source-sink limitations, using a model system comparing a fast-growing domesticated annual barley (Hordeum vulgare cv. NFC Tipple) with a slow-growing wild perennial relative (Hordeum bulbosum). Source strength was manipulated by growing plants at sub-ambient and elevated CO2 concentrations ([CO2 ]). Limitations on vegetative growth imposed by source and sink were diagnosed by measuring relative growth rate, developmental plasticity, photosynthesis and major carbon and nitrogen metabolite pools. Growth was sink limited in the annual but source limited in the perennial. RGR and carbon acquisition were higher in the annual, but photosynthesis responded weakly to elevated [CO2 ] indicating that source strength was near maximal at current [CO2 ]. In contrast, photosynthetic rate and sink development responded strongly to elevated [CO2 ] in the perennial, indicating significant source limitation. Sink limitation was avoided in the perennial by high sink plasticity: a marked increase in tillering and root:shoot ratio at elevated [CO2 ], and lower non-structural carbohydrate accumulation. Alleviating sink limitation during vegetative development could be important for maximising growth of elite cereals under future elevated [CO2 ]

    Combining Livestock with Cash Crops on Blackland Farms.

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    Nutrient sink limitation constrains growth in two barley species with contrasting growth strategies

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    Mineral nutrients exert important limitations on plant growth. Growth is limited by the nutrient source when it is constrained by nutrient availability and uptake, which may simultaneously limit investment in photosynthetic proteins, leading to carbon source limitation. However, growth may also be limited by nutrient utilization in sink tissue. The relative importance of these processes is contested, with crop and vegetation models typically assuming source limitations of carbon and mineral nutrients (especially nitrogen). This study compared the importance of source and sink limitation on growth in a slower‐growing wild perennial barley (Hordeum bulbosum) and a faster‐growing domesticated annual barley (Hordeum vulgare), by applying a mineral nutrient treatment and measuring nitrogen uptake, growth, allocation, and carbon partitioning. We found that nitrogen uptake, growth, tillering, shoot allocation, and nitrogen storage were restricted by low nutrient treatments. Multiple lines of evidence suggest that low nutrient levels do not limit growth via carbon acquisition: (a) Carbohydrate storage does not increase at high nutrient levels. (b) Ratio of free amino acids to sucrose increases at high nutrient levels. (c) Shoot allocation increases at high nutrient levels. These data indicate that barley productivity is limited by the capacity for nutrient use in growth. Models must explicitly account for sink processes in order to properly simulate this mineral nutrient limitation of growth

    Using Stories in Coach Education

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    The purpose of this paper is to illustrate how storied representations of research can be used as an effective pedagogical tool in coach education. During a series of continuing professional development seminars for professional golf coaches, we presented our research in the form of stories and poems which were created in an effort to evoke and communicate the lived experiences of elite professional golfers. Following these presentations, we obtained written responses to the stories from 53 experienced coaches who attended the seminars. Analysis of this data revealed three ways in which coaches responded to the stories: (i) questioning; (ii) summarising; and (iii) incorporating. We conclude that these responses illustrate the potential of storied forms of representation to enhance professional development through stimulating reflective practice and increasing understanding of holistic, person-centred approaches to coaching athletes in high-performance sport

    Dispersion and collapse in stochastic velocity fields on a cylinder

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    The dynamics of fluid particles on cylindrical manifolds is investigated. The velocity field is obtained by generalizing the isotropic Kraichnan ensemble, and is therefore Gaussian and decorrelated in time. The degree of compressibility is such that when the radius of the cylinder tends to infinity the fluid particles separate in an explosive way. Nevertheless, when the radius is finite the transition probability of the two-particle separation converges to an invariant measure. This behavior is due to the large-scale compressibility generated by the compactification of one dimension of the space

    Comprehensive ascertainment of bleeding in patients prescribed different combinations of dual antiplatelet therapy (DAPT) and triple therapy (TT) in the UK:Study protocol for three population-based cohort studies emulating a € target trials' (the ADAPTT Study)

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    Introduction a € Real world' bleeding in patients exposed to different regimens of dual antiplatelet therapy (DAPT) and triple therapy (TT, DAPT plus an anticoagulant) have a clinical and economic impact but have not been previously quantified. Methods and analysis We will use linked Clinical Practice Research Datalink (CPRD) and Hospital Episode Statistics (HES) data to assemble populations eligible for three a € target trials' in patient groups: percutaneous coronary intervention (PCI); coronary artery bypass grafting (CABG); conservatively managed (medication only) acute coronary syndrome (ACS). Patients ≄18 years old will be eligible if, in CPRD records, they have: ≄1 year of data before the index event; no prescription for DAPT or anticoagulants in the preceding 3 months; a prescription for aspirin or DAPT within 2 months after discharge from the index event. The primary outcome will be any bleeding event (CPRD or HES) up to 12 months after the index event. We will estimate adjusted HR for time to first bleeding event comparing: aspirin and clopidogrel (reference) versus aspirin and prasugrel or aspirin and ticagrelor after PCI; and aspirin (reference) versus aspirin and clopidogrel after CABG and ACS. We will describe rates of bleeding in patients prescribed TT (DAPT plus an anticoagulant). Potential confounders will be identified systematically using literature review, semistructured interviews with clinicians and a short survey of clinicians. We will conduct sensitivity analyses addressing the robustness of results to the study's main limitation - that we will not be able to identify the intervention group for patients whose bleeding event occurs before a DAPT prescription in CPRD. Ethics and dissemination This protocol was approved by the Independent Scientific Advisory Committee for the UK Medicines and Healthcare Products Regulatory Agency Database Research (protocol 16-126R) and the South West Cornwall and Plymouth Research Ethics Committee (17/SW/0092). The findings will be presented in peer-reviewed journals, lay summaries and briefing papers to commissioners/other stakeholders. Trial registration number 76607611; Pre-results

    Health Literacy and Demographic Disparities in HIV Care Continuum Outcomes

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    Studies evaluating the association between human immunodeficiency virus (HIV) infection continuum of care outcomes [antiretroviral (ART) adherence, retention in care, viral suppression] and health literacy have yielded conflicting results. Moreover, studies from the southern United States, a region of the country disproportionately affected by the HIV epidemic and low health literacy, are lacking. We conducted an observational cohort study among 575 people living with HIV (PLWH) at the Vanderbilt Comprehensive Care Clinic (Nashville, Tennessee). Health literacy was measured using the brief health literacy screen, a short tool which can be administered verbally by trained clinical personnel. Low health literacy was associated with a lack of viral suppression, but not with poor ART adherence or poor retention. Age and racial disparities in continuum of care outcomes persisted after accounting for health literacy, suggesting that factors in addition to health literacy must be addressed in order to improve outcomes for PLWH

    Rings and bars: unmasking secular evolution of galaxies

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    Secular evolution gradually shapes galaxies by internal processes, in contrast to early cosmological evolution which is more rapid. An important driver of secular evolution is the flow of gas from the disk into the central regions, often under the influence of a bar. In this paper, we review several new observational results on bars and nuclear rings in galaxies. They show that these components are intimately linked to each other, and to the properties of their host galaxy. We briefly discuss how upcoming observations, e.g., imaging from the Spitzer Survey of Stellar Structure in Galaxies (S4G), will lead to significant further advances in this area of research.Comment: Invited review at "Galaxies and their Masks", celebrating Ken Freeman's 70-th birthday, Sossusvlei, Namibia, April 2010. To be published by Springer, New York, editors D.L. Block, K.C. Freeman, & I. Puerari; minor change

    Dorsal root ganglion (Drg) and chronic pain

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    Context: Chronic neuropathic pain is a common condition, and up to 11.9 of the population have been reported to suffer from uncontrolled neuropathic pain. Chronic pain leads to significant morbidity, lowered quality of life, and loss of workdays, and thus carries a significant price tag in healthcare costs and lost productivity. dorsal root ganglia (DRG) stimulation has been recently increasingly reported and shows promising results in the alleviation of chronic pain. This paper reviews the background of DRG stimulation, anatomical, and clinical consideration and reviews the clinical evidence to support its use. Evidence Acquisition: The DRG span the length of the spinal cord and house the neurons responsible for sensation from the pe-riphery. They may become irritated by direct compression or local inflammation. Glial cells in the DRG respond to nerve injury, pro-ducing inflammatory markers and contribute to the development of chronic pain, even after the resolution of the original insult. While the underlying mechanism is still being explored, recent studies explored the efficacy of DRG stimulation and neuromodu-lation for chronic pain treatment. Results: Several reported cases and a small number of randomized trials were published in recent years, describing different meth-ods of DRG stimulation and neuromodulation with promising results. Though evidence quality is mostly low, these results provide evidence to support the utilization of this technique. Conclusions: Chronic neuropathic pain is a common condition and carries significant morbidity and impact on the quality of life. Recent evidence supports the use of DRG neuromodulation as an effective technique to control chronic pain. Though studies are still emerging, the evidence appears to support this technique. Further studies, including large randomized trials evaluating DRG modulation versus other interventional and non-interventional techniques, are needed to further elucidate the efficacy of this method. These studies are also likely to inform the patient selection and the course of treatment. © 2021, Author(s)

    Fitting the integrated Spectral Energy Distributions of Galaxies

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    Fitting the spectral energy distributions (SEDs) of galaxies is an almost universally used technique that has matured significantly in the last decade. Model predictions and fitting procedures have improved significantly over this time, attempting to keep up with the vastly increased volume and quality of available data. We review here the field of SED fitting, describing the modelling of ultraviolet to infrared galaxy SEDs, the creation of multiwavelength data sets, and the methods used to fit model SEDs to observed galaxy data sets. We touch upon the achievements and challenges in the major ingredients of SED fitting, with a special emphasis on describing the interplay between the quality of the available data, the quality of the available models, and the best fitting technique to use in order to obtain a realistic measurement as well as realistic uncertainties. We conclude that SED fitting can be used effectively to derive a range of physical properties of galaxies, such as redshift, stellar masses, star formation rates, dust masses, and metallicities, with care taken not to over-interpret the available data. Yet there still exist many issues such as estimating the age of the oldest stars in a galaxy, finer details ofdust properties and dust-star geometry, and the influences of poorly understood, luminous stellar types and phases. The challenge for the coming years will be to improve both the models and the observational data sets to resolve these uncertainties. The present review will be made available on an interactive, moderated web page (sedfitting.org), where the community can access and change the text. The intention is to expand the text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics & Space Scienc
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