| 1. |
- Kattge, Jens, et al.
(författare)
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TRY plant trait database - enhanced coverage and open access
- 2020
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Ingår i: Global Change Biology. - : Wiley-Blackwell. - 1354-1013 .- 1365-2486. ; 26:1, s. 119-188
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Tidskriftsartikel (refereegranskat)abstract
- Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.
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| 2. |
- Lembrechts, Jonas J., et al.
(författare)
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SoilTemp : A global database of near-surface temperature
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:11, s. 6616-6629
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Tidskriftsartikel (refereegranskat)abstract
- Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.
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| 3. |
- Broekman, Maarten J. E., et al.
(författare)
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Evaluating expert-based habitat suitability information of terrestrial mammals with GPS-tracking data
- 2022
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Ingår i: Global Ecology and Biogeography. - : Wiley. - 1466-822X .- 1466-8238. ; 31:8, s. 1526-1541
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Tidskriftsartikel (refereegranskat)abstract
- Aim: Macroecological studies that require habitat suitability data for many species often derive this information from expert opinion. However, expert-based information is inherently subjective and thus prone to errors. The increasing availability of GPS tracking data offers opportunities to evaluate and supplement expert-based information with detailed empirical evidence. Here, we compared expert-based habitat suitability information from the International Union for Conservation of Nature (IUCN) with habitat suitability information derived from GPS-tracking data of 1,498 individuals from 49 mammal species.Location: Worldwide.Time period: 1998-2021.Major taxa studied: Forty-nine terrestrial mammal species.Methods: Using GPS data, we estimated two measures of habitat suitability for each individual animal: proportional habitat use (proportion of GPS locations within a habitat type), and selection ratio (habitat use relative to its availability). For each individual we then evaluated whether the GPS-based habitat suitability measures were in agreement with the IUCN data. To that end, we calculated the probability that the ranking of empirical habitat suitability measures was in agreement with IUCN's classification into suitable, marginal and unsuitable habitat types.Results: IUCN habitat suitability data were in accordance with the GPS data (> 95% probability of agreement) for 33 out of 49 species based on proportional habitat use estimates and for 25 out of 49 species based on selection ratios. In addition, 37 and 34 species had a > 50% probability of agreement based on proportional habitat use and selection ratios, respectively.Main conclusions: We show how GPS-tracking data can be used to evaluate IUCN habitat suitability data. Our findings indicate that for the majority of species included in this study, it is appropriate to use IUCN habitat suitability data in macroecological studies. Furthermore, we show that GPS-tracking data can be used to identify and prioritize species and habitat types for re-evaluation of IUCN habitat suitability data.
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| 4. |
- Cooke, Marcus S, et al.
(författare)
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Interlaboratory comparison of methodologies for the measurement of urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine.
- 2009
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Ingår i: Biomarkers : biochemical indicators of exposure, response, and susceptibility to chemicals. - : Informa UK Limited. - 1366-5804. ; 14:2, s. 103-10
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Tidskriftsartikel (refereegranskat)abstract
- Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodGuo) is widely used as a marker of oxidative stress. Here we report the comparison of two, distinct chromatographic assays with an enzyme-linked immunosorbent assay (ELISA). The chromatographic assays displayed good agreement (r =:0.89, p < 0.0001), whereas there was markedly worse, albeit still significant, agreement with the ELISA (high-pressure liquid chromatography followed by gas chromatography (HPLC-GC/MS), r = 0.43; HPLC with electrochemical detection (HPLC-EC), r = 0.56; p < 0.0001). Mean values differed significantly between the chromatographic assays and the ELISA (HPLC-GC/MS 3.86, HPLC-EC 4.20, ELISA 18.70 ng mg(-1) creatinine; p < 0.0001). While it is reassuring to note good agreement between chromatographic assays, this study reveals significant short-comings in the ELISA, which brings into question its continued use in its present form.
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| 5. |
- Cuni-Sanchez, Aida, et al.
(författare)
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High aboveground carbon stock of African tropical montane forests
- 2021
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 596:7873, s. 536-542
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Tidskriftsartikel (refereegranskat)abstract
- Tropical forests store 40–50per cent of terrestrial vegetation carbon. However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests. Owing to climatic and soil changes with increasing elevation, AGC stocks are lower in tropical montane forests compared with lowland forests. Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4megagrams of carbon per hectare (95% confidence interval 137.1–164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network4 and about 70per cent and 32per cent higher than averages from plot networks in montane and lowland forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa8. We find that the low stem density and high abundance of large trees of African lowland forests is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to helpto guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse and carbon-rich ecosystems.
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| 6. |
- Jeppsson, Peter, et al.
(författare)
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Integrated design and verification system for finite element modelling
- 1993
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Ingår i: Concurrent Engineering - Research and Applications. - 1063-293X .- 1531-2003. ; 1:4, s. 213-217
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a computer-integrated system for design, manufacturing simulation, and inspection using a coordinate measurement machine (CMM). The work is concerned with the problem of predicting the shape of the container for hot isostatic pressing (HIP) and it focuses on the verification of a finite element (FE) simulation model for HIP. The verification is performed by comparing the simulated geometry of a real component produced by HIP. The geometry of the HIP component is measured by a CMM. The whole process from design and manufactunng simulation to inspection and geometry verification is performed within a computer-aided concurrent engineering (CACE) system. The system is built on both commercial and non-commercial software. The communication between a CMM, a geometnc modelling system, and the finite element simulation codes is developed. The manufacturing of a turbine component to net shape geometry using HIP is chosen as a demonstrator example. The benefits of the presented CACE system are time and cost savings as well as higher product quality.
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| 7. |
- Norman, Peter, et al.
(författare)
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A sophisticated platform for characterization, monitoring and control of machining
- 2006
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Ingår i: Measurement science and technology. - BRISTOL, ENGLAND : IOP Publishing. - 0957-0233 .- 1361-6501. ; 17:4, s. 847-854
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Tidskriftsartikel (refereegranskat)abstract
- The potential for improving the performance of machine tools is considerable. However, for this to be achieved without tool failure or product damage, the process must be sufficiently well understood to enable real-time monitoring and control to be applied. A unique sophisticated measurement platform has been developed and applied to two different machining centres, particularly for high-speed machining up to 24 000 rpm. Characterization and on-line monitoring of the dynamic behaviour of the machining processes has been carried out using both contact-based methods (accelerometer, force sensor) and non-contact methods (laser Doppler vibrometry and magnetic shaker) and numerical simulation (finite element based modal analysis). The platform was applied both pre-process and on-line for studying an aluminium testpiece based on a thin-walled aerospace component. Stability lobe diagrams for this specific machine/component combination were generated allowing selection of optimal process parameters giving stable cutting and metal removal rates some 8-10 times higher than those possible in unstable machining. Based on dynamic characterization and monitoring, a concept for an adaptive control with constraints based machine tool controller has been developed. The developed platform can be applied in manifold machining situations. It offers a reliable way of achieving significant process improvement
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| 8. |
- Svoboda, Ales, et al.
(författare)
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Integrated approach for prediction of stability limits for machining with large volumes of material removal
- 2008
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 46:12, s. 3207-3222
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Tidskriftsartikel (refereegranskat)abstract
- High-speed machining of thin-walled structures is widely used in the aeronautical industry. Higher spindle speed and machining feed rate, combined with a greater depth of cut, increases the removal rate and with it, productivity. The combination of higher spindle speed and depth of cut makes instabilities (chatter) a far more significant concern. Chatter causes reduced surface quality and accelerated tool wear. Since chatter is so prevalent, traditional cutting parameters and processes are frequently rendered ineffective and inaccurate. For the machine tool to reach its full utility, the chatter vibrations must be identified and avoided. In order to avoid chatter and implement optimum cutting parameters, the machine tool including all components and the work piece must be dynamically mapped to identify vibration characteristics. The aim of the presented work is to develop a model for the prediction of stability limits as a function of process parameters. The model consists of experimentally measured vibration properties of the spindle-tool, and finite element calculations of the work piece in (three) different stages of the process. Commercial software packages used for integration into the model prove to accomplish demands for functionality and performance. A reference geometry that is typical for an aircraft detail is used for evaluation of the prediction methodology. In order to validate the model, the stability limits predicted by the use of numerical simulation are compared with the results based on the experimental work.
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| 9. |
- Svoboda, Peter, 1963-
(författare)
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Mechanisms of formation and protection against oxidative DNA damage in vitro and in vivo
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Oxidative DNA damage has been linked to cancer and aging as well as other diseases. The aim of this thesis was to study the mechanisms for DNA damage generated in cells or in vitro systems by ionizing radiation or transition metals like iron ions. The damage primarily studied, was 7,8-dihydro-8-oxo-2'-deoxyguanosine (8-oxo-dG), formed by the attack of hydroxyl radical on DNA. Due to its incorrect base pairing with deoxyadenosine during cell replication, 8-oxo-dG is potentially mutagenic. This base damage was analysed with the method of high performance liquid chromatography and electrochemical detection. Also other endpoints of DNA damage were measured, such as the formation of DNA strand breaks with the alkali unwinding assay.Oxidation of iron ions was shown to be dependent on chelation to phosphate ions in solution as well as phosphate bound to DNA. Increasing the ratio of phosphate to ferrous iron (Fe2+) was correlated with the increased formation of 8-oxo-dG. Quin2, a metal chelator, was shown to redox cycle normally unreactive ferric iron (Fe3+) to its reduced form, Fe2+ in the presence of hydrogen peroxide, thereby producing hydroxyl radicals and damage such as 8-oxo-dG. Compounds with these properties would thus be considered as potentially mutagenic.In vitro, it was seen that the yield of 8-oxo-dG was severalfold higher upon irradiation of DNA as compared to irradiation of deoxyguanosine in solution, due to properties of the DNA structure itself. Adding scavengers to DNA, highest protection against damage could be seen using thiols with positive net charge, due to the formation of a counterion condensation complex with the negatively charged DNA, thus protecting more efficiantly against oxygen radical damage. The novel finding was that scavengers with reducing properties, like thiols or ascorbate, added to the nucleoside deoxyguanosine in solution, increased the radiation induced formation of 8-oxo-dG severalfold.Further, the protective effect of chromatin conformation was studied. The yield of radiation induced DNA damage increased when removing low molecular weight nuclear components upon permeabilisation of cells, demonstrating a larger role of hydroxyl radicals for the formation of 8-oxo-dG relative to DNA strand breaks. The removal of histones produced the highest levels of DNA damage, in the form of DNA strand breaks and 8-oxo-dG. In histone free DNA, thiol with positive net charge provided the best protection against formation of 8-oxo-dG.In vivo formation of 8-oxo-dG was studied in rats fed diets supplemented with iron and/or alcohol. In response to iron overload there was only a minor, insignificant, increase of 8-oxo-dG in rat liver cells, and a synergistic effect of iron and alcohol on cytotoxicity but with no genotoxicity.The excretion of 8-oxo-dG in urine was followed in response to radiotherapy of patients treated for breast cancer. The levels of 8-oxo-dG in the urine, before and in response to radiotherapy, correlated with the patients radiosensitivity. Thus, patients with higher radiosensitivity were considered to have a lower repair capacity for this damage.
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