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Sökning: WFRF:(Bokhorst J. M.)

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1.
  • Potapov, Anton M., et al. (författare)
  • Global fine-resolution data on springtail abundance and community structure
  • 2024
  • Ingår i: Scientific Data. - : Nature Publishing Group. - 2052-4463. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Springtails (Collembola) inhabit soils from the Arctic to the Antarctic and comprise an estimated ~32% of all terrestrial arthropods on Earth. Here, we present a global, spatially-explicit database on springtail communities that includes 249,912 occurrences from 44,999 samples and 2,990 sites. These data are mainly raw sample-level records at the species level collected predominantly from private archives of the authors that were quality-controlled and taxonomically-standardised. Despite covering all continents, most of the sample-level data come from the European continent (82.5% of all samples) and represent four habitats: woodlands (57.4%), grasslands (14.0%), agrosystems (13.7%) and scrublands (9.0%). We included sampling by soil layers, and across seasons and years, representing temporal and spatial within-site variation in springtail communities. We also provided data use and sharing guidelines and R code to facilitate the use of the database by other researchers. This data paper describes a static version of the database at the publication date, but the database will be further expanded to include underrepresented regions and linked with trait data.
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2.
  • Lembrechts, Jonas J., et al. (författare)
  • Global maps of soil temperature
  • 2022
  • Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 28:9, s. 3110-3144
  • Tidskriftsartikel (refereegranskat)abstract
    • Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world's major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean=3.0±2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6±2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7±2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications.
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3.
  • Potapov, Anton M., et al. (författare)
  • Globally invariant metabolism but density-diversity mismatch in springtails
  • 2023
  • Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 14:1
  • Tidskriftsartikel (refereegranskat)abstract
    • Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.
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4.
  • Bokhorst, J. M., et al. (författare)
  • Assessment of individual tumor buds using keratin immunohistochemistry: moderate interobserver agreement suggests a role for machine learning
  • 2020
  • Ingår i: Modern Pathology. - : NATURE PUBLISHING GROUP. - 0893-3952 .- 1530-0285. ; 33:5, s. 825-833
  • Tidskriftsartikel (refereegranskat)abstract
    • Tumor budding is a promising and cost-effective biomarker with strong prognostic value in colorectal cancer. However, challenges related to interobserver variability persist. Such variability may be reduced by immunohistochemistry and computer-aided tumor bud selection. Development of computer algorithms for this purpose requires unequivocal examples of individual tumor buds. As such, we undertook a large-scale, international, and digital observer study on individual tumor bud assessment. From a pool of 46 colorectal cancer cases with tumor budding, 3000 tumor bud candidates were selected, largely based on digital image analysis algorithms. For each candidate bud, an image patch (size 256 x 256 mu m) was extracted from a pan cytokeratin-stained whole-slide image. Members of an International Tumor Budding Consortium (n = 7) were asked to categorize each candidate as either (1) tumor bud, (2) poorly differentiated cluster, or (3) neither, based on current definitions. Agreement was assessed with Cohens and Fleiss Kappa statistics. Fleiss Kappa showed moderate overall agreement between observers (0.42 and 0.51), while Cohens Kappas ranged from 0.25 to 0.63. Complete agreement by all seven observers was present for only 34% of the 3000 tumor bud candidates, while 59% of the candidates were agreed on by at least five of the seven observers. Despite reports of moderate-to-substantial agreement with respect to tumor budding grade, agreement with respect to individual pan cytokeratin-stained tumor buds is moderate at most. A machine learning approach may prove especially useful for a more robust assessment of individual tumor buds.
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6.
  • Hollister, R. D., et al. (författare)
  • A review of open top chamber (OTC) performance across the ITEX Network
  • 2023
  • Ingår i: Arctic Science. - : Canadian Science Publishing. - 2368-7460. ; 9:2, s. 331-344
  • Tidskriftsartikel (refereegranskat)abstract
    • Open top chambers (OTCs) were adopted as the recommended warming mechanism by the International Tundra Experiment network in the early 1990s. Since then, OTCs have been deployed across the globe. Hundreds of papers have reported the im-pacts of OTCs on the abiotic environment and the biota. Here, we review the impacts of the OTC on the physical environment, with comments on the appropriateness of using OTCs to characterize the response of biota to warming. The purpose of this review is to guide readers to previously published work and to provide recommendations for continued use of OTCs to under -stand the implications of warming on low stature ecosystems. In short, the OTC is a useful tool to experimentally manipulate temperature; however, the characteristics and magnitude of warming varies greatly in different environments; therefore, it is important to document chamber performance to maximize the interpretation of biotic response. When coupled with long-term monitoring, warming experiments are a valuable means to understand the impacts of climate change on natural ecosystems.
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7.
  • Elia, M, et al. (författare)
  • Enteral (oral or tube administration) nutritional support and eicosapentaenoic acid in patients with cancer: a systematic review.
  • 2006
  • Ingår i: International journal of oncology. - 1019-6439. ; 28:1, s. 5-23
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this systematic review was to determine the efficacy and potential benefits of enteral nutritional support [oral nutritional supplements (ONS) or enteral tube feeding (ETF)], and eicosapentaenoic acid (EPA, free acid, ethyl esters or fish oil; provided as capsules or enriched ONS or ETF) in patients with cancer. Clinical studies were identified using electronic databases, and studies were selected according to predetermined criteria. For each treatment modality (chemo/radiotherapy, surgery, and palliative care), the comparisons of interest were nutritional support vs. routine care (no nutritional support), EPA supplement (capsule or enriched ONS or ETF) vs. routine care (no supplement or standard supplement), ETF vs. parenteral nutrition (PN). The reviewed outcomes were dietary intake, anthropometry, clinical (mortality, length of hospital stay, complications, and quality of life) and haematological/biochemical (white blood cell count, serum transferrin and albumin, CD3-positive lymphocytes, and inflammatory markers). Meta-analyses were performed where possible. In patients undergoing radiotherapy, meta-analysis showed that ONS significantly increase dietary intake (381 kcal/day, 95% CI 193 to 569 in 3 RCTs) compared to routine care. In patients undergoing surgery, meta-analyses showed that ETF results in a significantly shorter length of hospital stay (1.72 fewer days, 95% CI 0.90 to 2.54 in 8 RCTs), lower incidence of any complications (OR 0.62, 95% CI 0.50 to 0.77 in 4 RCTs) and infectious complications (OR 0.67, 95% CI 0.55 to 0.82 in 11 RCTs) and lower sepsis scores (2.21 points, 95% CI 1.49 to 2.92 in 2 RCTs), but no difference in mortality (OR 0.72, 95% CI 0.40 to 1.29 in 7 RCTs) compared to PN. There was also no difference in mortality between ONS or ETF vs. routine care in patients undergoing chemotherapy/radiotherapy (OR 1.00, 95% CI 0.62-1.61 in 4 RCTs) or surgery (OR 2.44, 95% CI 0.75 to 7.95 in 4 RCTs). Individual studies of EPA supplementation as capsules showed improvements in survival, complications and inflammatory markers in patients undergoing bone marrow transplant (BMT). In palliative care patients receiving EPA-enriched ONS or capsules, there were inconsistent positive effects on survival and quality of life. In those undergoing surgery, EPA-enriched ETF had no effect. Further research is required to elucidate the clinical efficacy of enteral nutrition support, including the potential benefits of EPA supplementation, in patients with cancer.
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8.
  • Smit, Marloes A., et al. (författare)
  • Deep learning based tumor–stroma ratio scoring in colon cancer correlates with microscopic assessment
  • 2023
  • Ingår i: Journal of Pathology Informatics. - : Elsevier B.V.. - 2229-5089 .- 2153-3539. ; 14
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: The amount of stroma within the primary tumor is a prognostic parameter for colon cancer patients. This phenomenon can be assessed using the tumor–stroma ratio (TSR), which classifies tumors in stroma-low (≤50% stroma) and stroma-high (>50% stroma). Although the reproducibility for TSR determination is good, improvement might be expected from automation. The aim of this study was to investigate whether the scoring of the TSR in a semi- and fully automated method using deep learning algorithms is feasible. Methods: A series of 75 colon cancer slides were selected from a trial series of the UNITED study. For the standard determination of the TSR, 3 observers scored the histological slides. Next, the slides were digitized, color normalized, and the stroma percentages were scored using semi- and fully automated deep learning algorithms. Correlations were determined using intraclass correlation coefficients (ICCs) and Spearman rank correlations. Results: 37 (49%) cases were classified as stroma-low and 38 (51%) as stroma-high by visual estimation. A high level of concordance between the 3 observers was reached, with ICCs of 0.91, 0.89, and 0.94 (all P < .001). Between visual and semi-automated assessment the ICC was 0.78 (95% CI 0.23–0.91, P-value 0.005), with a Spearman correlation of 0.88 (P < .001). Spearman correlation coefficients above 0.70 (N=3) were observed for visual estimation versus the fully automated scoring procedures. Conclusion: Good correlations were observed between standard visual TSR determination and semi- and fully automated TSR scores. At this point, visual examination has the highest observer agreement, but semi-automated scoring could be helpful to support pathologists. © 2023 The Authors
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9.
  • Virkkala, Anna Maria, et al. (författare)
  • Statistical upscaling of ecosystem CO2 fluxes across the terrestrial tundra and boreal domain : Regional patterns and uncertainties
  • 2021
  • Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 27:17, s. 4040-4059
  • Tidskriftsartikel (refereegranskat)abstract
    • The regional variability in tundra and boreal carbon dioxide (CO2) fluxes can be high, complicating efforts to quantify sink-source patterns across the entire region. Statistical models are increasingly used to predict (i.e., upscale) CO2 fluxes across large spatial domains, but the reliability of different modeling techniques, each with different specifications and assumptions, has not been assessed in detail. Here, we compile eddy covariance and chamber measurements of annual and growing season CO2 fluxes of gross primary productivity (GPP), ecosystem respiration (ER), and net ecosystem exchange (NEE) during 1990–2015 from 148 terrestrial high-latitude (i.e., tundra and boreal) sites to analyze the spatial patterns and drivers of CO2 fluxes and test the accuracy and uncertainty of different statistical models. CO2 fluxes were upscaled at relatively high spatial resolution (1 km2) across the high-latitude region using five commonly used statistical models and their ensemble, that is, the median of all five models, using climatic, vegetation, and soil predictors. We found the performance of machine learning and ensemble predictions to outperform traditional regression methods. We also found the predictive performance of NEE-focused models to be low, relative to models predicting GPP and ER. Our data compilation and ensemble predictions showed that CO2 sink strength was larger in the boreal biome (observed and predicted average annual NEE −46 and −29 g C m−2 yr−1, respectively) compared to tundra (average annual NEE +10 and −2 g C m−2 yr−1). This pattern was associated with large spatial variability, reflecting local heterogeneity in soil organic carbon stocks, climate, and vegetation productivity. The terrestrial ecosystem CO2 budget, estimated using the annual NEE ensemble prediction, suggests the high-latitude region was on average an annual CO2 sink during 1990–2015, although uncertainty remains high.
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