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  • 1
    In: tm - Technisches Messen, 09/01/2018, Vol.85(s1), pp.s59-s65
    Description: Die optische dreidimensionale Formerfassung spiegelnd reflektierender Objekte ist in der Messtechnik immer noch eine schwierige Aufgabe. Die Deflektometrie rekonstruiert die Oberfläche durch Beobachtung verzerrter Bilder einer reflektierten Referenzszene. In diesem Beitrag wird erstmalig ein neuer Ansatz präsentiert, bei dem das deflektometrische Messverfahren effizient mit einer Lichtfeldkamera kombiniert wird. Eine Interpretation der Kamera als hochgradig multiples Kamera-Array erlaubt es, das deflektometrische Messproblem mit einem Multi-Stereo-Ansatz zu lösen. Die Leistungsfähigkeit der Oberflächenrekonstruktion wird in experimentellen Messungen bestätigt und es zeigt sich, dass durch die Kombination von Deflektometrie mit Lichtfeldkameras hohe Genauigkeiten erreicht werden können.
    Keywords: Deflektometrie ; Lichtfeldkamera ; 3d-Rekonstruktion ; Deflectometry ; Light-Field Camera ; 3d Reconstruction;
    ISSN: 0171-8096
    E-ISSN: 2196-7113
    Source: Walter de Gruyter (via CrossRef)
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  • 2
    Language: English
    Description: This dataset provides the data tables for the manuscript: “Uhlig, D., Amelung, W. and von Blanckenburg, F.: A deep phosphorous weathering source for forest ecosystems“. Various samples were taken in two mountainous headwater catchments at the Black Forest (Conventforest) and the Bavarian Forest (Mitterfels) in Germany. The dataset contains major and trace element concentrations as well as isotope data (87^Sr/86^Sr, 10^Be(meteoric)/9^Be) of soil, saprolite, weathered bedrock and unweathered bedrock samples from drilling cores (depth: 20 m, Conventforest, and 30 m, Mitterfels). Additionally, chemical and isotope data from living leaves, needles, and stem wood (heartwood and sapwood) of Fagus sylvatica and Picea abies from both locations are reported. Further, the dataset contains phosphorous (P) concentrations from various P fractions of soil, saprolite and bedrock obtained by sequential extractions following the Hedley fractionation method. Total denudation rates (D) obtained from in situ 10^Be concentrations and phosphorous fluxes such as the net solubilisation fluxes (W_regolith^P) and wet and dry deposition fluxes (Dep_wet^P, Dep_dry^P), as well as phosphorous ecosystem uptake fluxes (U^P) are also included in the dataset. Finally, we present data of weathering indicators such as...
    Keywords: Net Solubilisation Flux ; P Ecosystem Uptake Flux ; Hedley Fractionation ; Meteoric Beryllium ; Radiogenic Strontium
    Source: DataCite
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  • 3
    Language: English
    In: Biogeosciences, June 26, 2017, Vol.14(12), p.3111
    Description: Plants and soil microbiota play an active role in rock weathering and potentially couple weathering at depth with erosion at the soil surface. The nature of this coupling is still unresolved because we lacked means to quantify the passage of chemical elements from rock through higher plants. In a temperate forested landscape characterised by relatively fast (#xE2;#x88;#xBC; 220 t km.sup.-2 yr.sup.-1) denudation and a kinetically limited weathering regime of the Southern Sierra Critical Zone Observatory (SSCZO), California, we measured magnesium (Mg) stable isotopes that are sensitive indicators of Mg utilisation by biota. We find that Mg is highly bio-utilised: 50-100 % of the Mg released by chemical weathering is taken up by forest trees. To estimate the tree uptake of other bio-utilised elements (K, Ca, P and Si) we compared the dissolved fluxes of these elements and Mg in rivers with their solubilisation fluxes from rock (rock dissolution flux minus secondary mineral formation flux). We find a deficit in the dissolved fluxes throughout, which we attribute to the nutrient uptake by forest trees. Therefore both the Mg isotopes and the flux comparison suggest that a substantial part of the major element weathering flux is consumed by the tree biomass. The enrichment of .sup.26 Mg over .sup.24 Mg in tree trunks relative to leaves suggests that tree trunks account for a substantial fraction of the net uptake of Mg. This isotopic and elemental compartment separation is prevented from obliteration (which would occur by Mg redissolution) by two potential effects. Either the mineral nutrients accumulate today in regrowing forest biomass after clear cutting, or they are exported in litter and coarse woody debris (CWD) such that they remain in solid biomass. Over pre-forest-management weathering timescales, this removal flux might have been in operation in the form of natural erosion of CWD. Regardless of the removal mechanism, our approach provides entirely novel means towards the direct quantification of biogenic uptake following weathering. We find that Mg and other nutrients and the plant-beneficial element Si (bio-elements) are taken up by trees at up to 6 m depth, and surface recycling of all bio-elements but P is minimal. Thus, in the watersheds of the SSCZO, the coupling between erosion and weathering might be established by bio-elements that are taken up by trees, are not recycled and are missing in the dissolved river flux due to erosion as CWD and as leaf-derived bio-opal for Si. We suggest that the partitioning of a biogenic weathering flux into eroded plant debris might represent a significant global contribution to element export after weathering in eroding mountain catchments that are characterised by a continuous supply of fresh mineral nutrients.
    Keywords: Weathering – Research ; Magnesium (Metal) – Research ; Forests – Research ; Ecosystems – Research
    ISSN: 1726-4170
    E-ISSN: 17264189
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  • 4
    Language: English
    In: Chemical Geology, 10 October 2018, Vol.497, pp.74-87
    Description: Forest ecosystem nutrition and rock weathering are intimately linked through the supply of mineral nutrients and recycling (re-utilisation of nutrients released from plant litter during mineralisation). Here, we report on novel applications of Mg stable isotopes in combination with mass balance calculations to quantify nutrient supply (from bedrock, atmospheric wet and dry deposition) and recycling in a tropical ecosystem, characterised by a supply-limited weathering regime in the Central Highlands of Sri Lanka. We measured Mg stable isotopes, radiogenic Sr isotope ratios, and element concentrations in the different compartments of the Earth's Critical Zone (bedrock, saprolite, soil, soil pore water, stream water and vegetation) as tracers for element mass fluxes and pathways. We find that in the clay-rich saprolite Mg isotopes are fractionated towards isotopically heavy Mg during secondary mineral formation. Soil pore water and stream water are the complementary isotopically light reservoirs. The Mg isotope composition of above-ground vegetation is on average identical to soil pore water. Based on these observations we suggest that a tight near-surface mineral nutrient loop between plants and soil sustains the tropical forest ecosystem. This loop is disconnected from the rock weathering nutrient source in the saprolite beneath soil. External atmospheric wet and dry inputs (mainly Mg and Ca) strongly contribute to the plant-available nutrient budget that the nutrient depleted regolith does not supply. These findings, based on Mg stable isotopes, agree with independently-obtained information on bio-element (P, K, Ca, Mg, Si) recycling. This nutrient supply setting contrasts with that reported for the Southern Sierra Nevada (USA), where a kinetically limited weathering regime prevails. Our study illustrates the application of new flux estimators based on elemental and metal stable isotope measurements across a range of climate and weathering regimes.
    Keywords: Tropical Montane Ecosystems ; Mg Stable Isotopes ; Bio-Element Cycling and Recycling ; Chemical Weathering ; Critical Zone ; Supply-Limitation ; Geology
    ISSN: 0009-2541
    E-ISSN: 1872-6836
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  • 5
    Language: English
    In: Biogeosciences Discussions, 01/16/2017, pp.1-28
    ISSN: Biogeosciences Discussions
    E-ISSN: 1810-6285
    Source: CrossRef
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  • 6
    In: Zeitschrift für Kultur- und Kollektivwissenschaft, 2018, Vol.4(1), pp.341-358
    ISSN: 2363-6300
    E-ISSN: 2363-6319
    Source: Walter de Gruyter GmbH
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  • 7
    Language: English
    In: Frontiers in Earth Science, 01 July 2019, Vol.7
    Description: Mineral nutrient cycling between trees and the forest floor is key to forest ecosystem nutrition. However, in sloping, well-drained landscapes the forest floor experiences permanent nutrient loss in particulate form by plant litter erosion and as solute after plant litter decomposition, solubilisation, and export. To prevent nutrient deficit, a replenishing mechanism must be in operation that we suggest to be sourced in the subsoil and the weathering zone beneath it, provided that atmospheric input is insufficient. To explore such a mechanism, we quantified deep (up to 20 m depth) weathering and mineral nutrient cycling in two montane, temperate forest ecosystems in Southern Germany: Black Forest (CON) and Bavarian Forest (MIT). From measurements of the inventories, turnover times, and fluxes of macronutrients (K, Ca, Mg, P) we found evidence for a fast, shallow “organic nutrient cycle”, and a slow, deep “geogenic nutrient pathway”. We found that the finite nutrient pool size of the forest floor persists for a few years only. Despite this loss, foliar nutrient concentrations in Picea abies and Fagus sylvatica do not indicate deficiency. We infer that ultimately the biologically available fraction in the deep regolith (CON: 3–7 m, MIT: 3–17 m) balances nutrient loss from the forest floor and is also decisive for the level of the forest trees' mineral nutrient stoichiometry. Intriguingly, although the nutrient supply fluxes from chemical weathering at CON are twice those of MIT, nutrient uptake fluxes into trees do not differ. The organic nutrient cycle apparently regulates the efficiency of nutrient re-utilization from organic matter to cater for differences in its replenishment by the deep geogenic nutrient pathway, and thereby ensures long-term forest ecosystem nutrition.
    Keywords: Mineral Nutrients ; Ecosystem Nutrition ; Chemical Weathering ; Plant Litter Erosion ; Dissolved Plant Litter Export ; Geology
    E-ISSN: 2296-6463
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  • 8
    Language: English
    Description: This dataset is a supplementary dataset to the manuscript: “Uhlig, D., Schuessler, J. A., Bouchez, J. L., Dixon, J., and von Blanckenburg, F.: Quantifying nutrient uptake as driver of rock weathering in forest ecosystems by magnesium stable isotopes, Biogeosciences, 2017“. The dataset contains physicochemical parameters of stream water (pH, temperature, conductivity discharge, alkalinity) , and chemical and Mg isotope analyses of stream water, vegetation, soil, saprolite, weathered bedrock and unweathered bedrock of three headwater catchments at Providence Creek in the Southern Sierra Nevada, California, USA. Further, the dataset contains soil and saprolite weathering indicators such as the chemical depletion fraction (CDF) and mass transfer coefficients, as well as elemental regolith production fluxes, elemental net solubilisation fluxes, elemental dissolved river fluxes, elemental litterfall fluxes, nutrient recycling fluxes and elemental dissolved export efficiencies that rely on measured data reported in the above study and data from literature. These data and metrics were used to track the pathway of Mg and other nutrients through the headwater catchments at the Critical Zone Observatory of the Southern Sierra Nevada....
    Keywords: Dissolved Export Efficiency ; Mg Stable Isotopes ; Mass Transfer Coefficient ; Chemical Depletion Fraction ; Litterfall Fluxes
    Source: DataCite
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  • 9
    Language: English
    In: Journal of Plant Nutrition and Soil Science, August 2016, Vol.179(4), pp.425-438
    Description: Understanding and quantification of phosphorus (P) fluxes are key requirements for predictions of future forest ecosystems changes as well as for transferring lessons learned from natural ecosystems to croplands and plantations. This review summarizes and evaluates the recent knowledge on mechanisms, magnitude, and relevance by which dissolved and colloidal inorganic and organic P forms can be translocated within or exported from forest ecosystems. Attention is paid to hydrological pathways of P losses at the soil profile and landscape scales, and the subsequent influence of P on aquatic ecosystems. New (unpublished) data from the German Priority Program 1685 “” were added to provide up‐to‐date flux‐based information. Nitrogen (N) additions increase the release of water‐transportable P forms. Most P found in percolates and pore waters belongs to the so‐called dissolved organic P (DOP) fractions, rich in orthophosphate‐monoesters and also containing some orthophosphate‐diesters. Total solution P concentrations range from ca. 1 to 400 µg P L, with large variations among forest stands. Recent sophisticated analyses revealed that large portions of the DOP in forest stream water can comprise natural nanoparticles and fine colloids which under extreme conditions may account for 40–100% of the P losses. Their translocation within preferential flow passes may be rapid, mediated by storm events. The potential total P loss through leaching into subsoils and with streams was found to be less than 50 mg P m a, suggesting effects on ecosystems at centennial to millennium scale. All current data are based on selected snapshots only. Quantitative measurements of P fluxes in temperate forest systems are nearly absent in the literature, probably due to main research focus on the C and N cycles. Therefore, we lack complete ecosystem‐based assessments of dissolved and colloidal P fluxes within and from temperate forest systems.
    Keywords: Forest Ecosystem ; Phosphorus ; Fluxes ; Soil ; Processes ; Hydrology
    ISSN: 1436-8730
    E-ISSN: 1522-2624
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  • 10
    Language: English
    In: Journal of General Internal Medicine, 2014, Vol.29(4), pp.670-679
    Description: Many patients of all ages have multiple conditions, yet clinicians often lack explicit guidance on how to approach clinical decision-making for such people. Most recommendations from clinical practice guidelines (CPGs) focus on the management of single diseases, and may be harmful or impractical for patients with multimorbidity. A major barrier to the development of guidance for people with multimorbidity stems from the fact that the evidence underlying CPGs derives from studies predominantly focused on the management of a single disease. In this paper, the investigators from the Improving Guidelines for Multimorbid Patients Study Group present consensus-based recommendations for guideline developers to make guidelines more useful for the care of people with multimorbidity. In an iterative process informed by review of key literature and experience, we drafted a list of issues and possible approaches for addressing important coexisting conditions in each step of the guideline development process, with a focus on considering relevant interactions between the conditions, their treatments and their outcomes. The recommended approaches address consideration of coexisting conditions at all major steps in CPG development, from nominating and scoping the topic, commissioning the work group, refining key questions, ranking importance of outcomes, conducting systematic reviews, assessing quality of evidence and applicability, summarizing benefits and harms, to formulating recommendations and grading their strength. The list of issues and recommendations was reviewed and refined iteratively by stakeholders. This framework acknowledges the challenges faced by CPG developers who must make complex judgments in the absence of high-quality or direct evidence. These recommendations require validation through implementation, evaluation and refinement.
    Keywords: guidelines ; multimorbidity ; comorbidity ; grading evidence
    ISSN: 0884-8734
    E-ISSN: 1525-1497
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