37 research outputs found

    GREGOR, a 1.5 m Gregory-type telescope for solar observation

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    GREGOR is a high-resolution solar telescope with an aperture of 1.5 m. It will be equipped with an adaptive optics system and is designed for high-precision measurements of magnetic fields and plasma motions in the solar atmosphere and chromosphere with a resolution of 70 km on the Sun. GREGOR will replace the 30 years old Gregory Coude Telescope at the Observatorio del Teide on Tenerife. We describe the optical design and the focal plane instrumentation. In concert with the other solar telescopes at Teide Observatory it will be useful for studying the dynamics of the solar atmosphere and of the underlying processes. GREGOR will also serve as a test bed for next-generation solar telescopes

    Global patterns and environmental drivers of forest functional composition

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    Aim To determine the relationships between the functional trait composition of forest communities and environmental gradients across scales and biomes and the role of species relative abundances in these relationships. Location Global. Time period Recent. Major taxa studied Trees. Methods We integrated species abundance records from worldwide forest inventories and associated functional traits (wood density, specific leaf area and seed mass) to obtain a data set of 99,953 to 149,285 plots (depending on the trait) spanning all forested continents. We computed community-weighted and unweighted means of trait values for each plot and related them to three broad environmental gradients and their interactions (energy availability, precipitation and soil properties) at two scales (global and biomes). Results Our models explained up to 60% of the variance in trait distribution. At global scale, the energy gradient had the strongest influence on traits. However, within-biome models revealed different relationships among biomes. Notably, the functional composition of tropical forests was more influenced by precipitation and soil properties than energy availability, whereas temperate forests showed the opposite pattern. Depending on the trait studied, response to gradients was more variable and proportionally weaker in boreal forests. Community unweighted means were better predicted than weighted means for almost all models. Main conclusions Worldwide, trees require a large amount of energy (following latitude) to produce dense wood and seeds, while leaves with large surface to weight ratios are concentrated in temperate forests. However, patterns of functional composition within-biome differ from global patterns due to biome specificities such as the presence of conifers or unique combinations of climatic and soil properties. We recommend assessing the sensitivity of tree functional traits to environmental changes in their geographic context. Furthermore, at a given site, the distribution of tree functional traits appears to be driven more by species presence than species abundance

    Integrated global assessment of the natural forest carbon potential

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    Forests are a substantial terrestrial carbon sink, but anthropogenic changes in land use and climate have considerably reduced the scale of this system1. Remote-sensing estimates to quantify carbon losses from global forests2,3,4,5 are characterized by considerable uncertainty and we lack a comprehensive ground-sourced evaluation to benchmark these estimates. Here we combine several ground-sourced6 and satellite-derived approaches2,7,8 to evaluate the scale of the global forest carbon potential outside agricultural and urban lands. Despite regional variation, the predictions demonstrated remarkable consistency at a global scale, with only a 12% difference between the ground-sourced and satellite-derived estimates. At present, global forest carbon storage is markedly under the natural potential, with a total deficit of 226 Gt (model range = 151–363 Gt) in areas with low human footprint. Most (61%, 139 Gt C) of this potential is in areas with existing forests, in which ecosystem protection can allow forests to recover to maturity. The remaining 39% (87 Gt C) of potential lies in regions in which forests have been removed or fragmented. Although forests cannot be a substitute for emissions reductions, our results support the idea2,3,9 that the conservation, restoration and sustainable management of diverse forests offer valuable contributions to meeting global climate and biodiversity targets

    The global distribution and drivers of wood density and their impact on forest carbon stocks.

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    The density of wood is a key indicator of the carbon investment strategies of trees, impacting productivity and carbon storage. Despite its importance, the global variation in wood density and its environmental controls remain poorly understood, preventing accurate predictions of global forest carbon stocks. Here we analyse information from 1.1 million forest inventory plots alongside wood density data from 10,703 tree species to create a spatially explicit understanding of the global wood density distribution and its drivers. Our findings reveal a pronounced latitudinal gradient, with wood in tropical forests being up to 30% denser than that in boreal forests. In both angiosperms and gymnosperms, hydrothermal conditions represented by annual mean temperature and soil moisture emerged as the primary factors influencing the variation in wood density globally. This indicates similar environmental filters and evolutionary adaptations among distinct plant groups, underscoring the essential role of abiotic factors in determining wood density in forest ecosystems. Additionally, our study highlights the prominent role of disturbance, such as human modification and fire risk, in influencing wood density at more local scales. Factoring in the spatial variation of wood density notably changes the estimates of forest carbon stocks, leading to differences of up to 21% within biomes. Therefore, our research contributes to a deeper understanding of terrestrial biomass distribution and how environmental changes and disturbances impact forest ecosystems

    Co-limitation towards lower latitudes shapes global forest diversity gradients

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    The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Zellkinetik in Lymphdrüsen - I. Bestimmung der Desoxyribonucleinsäure-Synthesedauer bei Patienten mit chronischer lymphatischer Leukämie durch Doppelmarkierung mit 3 H-Thymidin und 14C-Thymidin in vivo.

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    Bei 8 Patienten mit chronischer lymphatischer Leukämie (CLL) wurde in vivo eine Doppelmarkierung mit 3H- und 14C-Thymidin durchgeführt. Es wurde die DNS-Synthesezeit (S-Zeit) der proliferierenden Zellen von aus Lymphknoten gewonnenen Schnitt- und Ausstrichpräparaten autoradiographisch untersucht und verglichen. Die errechnete S-Zeit schwankte zwischen 19,6 und 43,5 Std. Diese Befunde wurden mit den bisher bekannten Werten von S-Zeiten menschlicher Zellen verglichen und diskutiert

    High Pre-therapy [99mtc]pertechnetate Thyroid Uptake, Thyroid Size And Thyrostatic Drugs: Predictive Factors Of Failure In [ 131i]iodide Therapy In Graves' Disease

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    Background and objective: Several factors may interfere with the success rate of radioiodine therapy (RIT) in Graves' disease. Our aim was to evaluate, retrospectively, some of these factors in the outcome of RIT. Methods: Patient gender, age at diagnosis, ophthalmopathy, disease duration, thyroid size, drug used as clinical treatment, thionamide withdrawal period during RIT preparation, FT4, TSH and [99mTc]pertechnetate thyroid uptake prior to RIT were studied as potential interference factors for RIT success. Eighty-two Graves' disease patients were submitted to RIT after thionamide treatment failure. Prior to RIT, 67 patients were receiving methimazole and 15 propylthiouracil. Thirty-three patients received thionamides during RIT; in 49 patients the medication was withdrawn for 2-30 days. [99mTc] pertechnetate thyroid uptake was determined before RIT. Fixed doses of 370 MBq of [131I]iodide were administered to all patients. Results: Eleven patients became euthyroid; 40 became hypothyroid and 31 remained hyperthyroid. There was no association between outcome and age at diagnosis, gender, ophthalmopathy, pre-RIT FT4, TSH, antithyroid antibodies or thyrostatic drug. Multiple logistic regression showed higher probability of treatment success in patients with thyroid mass <53g (odds ratio (OR) = 8.9), with pre-RIT thyroid uptake <12.5% (OR = 4.1) and in patients who withdrew thionamide before RIT (OR = 4.9). Conclusions: Fixed doses of 370 MBq of radioiodine seem to be practical and effective for treating Graves' disease patients with [99mTc]pertechnetate uptake < 12.5% and thyroid mass < 53g. This treatment is clearly not recommended for patients with large goitre. 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    The inner experience of time

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    The striking diversity of psychological and neurophysiological models of ‘time perception’ characterizes the debate on how and where in the brain time is processed. In this review, the most prominent models of time perception will be critically discussed. Some of the variation across the proposed models will be explained, namely (i) different processes and regions of the brain are involved depending on the length of the processed time interval, and (ii) different cognitive processes may be involved that are not necessarily part of a core timekeeping system but, nevertheless, influence the experience of time. These cognitive processes are distributed over the brain and are difficult to discern from timing mechanisms. Recent developments in the research on emotional influences on time perception, which succeed decades of studies on the cognition of temporal processing, will be highlighted. Empirical findings on the relationship between affect and time, together with recent conceptualizations of self- and body processes, are integrated by viewing time perception as entailing emotional and interoceptive (within the body) states. To date, specific neurophysiological mechanisms that would account for the representation of human time have not been identified. It will be argued that neural processes in the insular cortex that are related to body signals and feeling states might constitute such a neurophysiological mechanism for the encoding of duration
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