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122 results on '"Sørensen, Peter B."'

2. An Integrated Data-Driven Strategy for Safe-by-Design Nanoparticles: The FP7 MODERN Project

Author

Brehm, Martin, Kafka, Alexander, Bamler, Markus, Kühne, Ralph, Schüürmann, Gerrit, Sikk, Lauri, Burk, Jaanus, Burk, Peeter, Tamm, Tarmo, Tämm, Kaido, Pokhrel, Suman, Mädler, Lutz, Kahru, Anne, Aruoja, Villem, Sihtmäe, Mariliis, Scott-Fordsmand, Janeck, Sorensen, Peter B., Escorihuela, Laura, Roca, Carlos P., Fernández, Alberto, Giralt, Francesc, Rallo, Robert, Tran, Lang, editor, Bañares, Miguel A., editor, and Rallo, Robert, editor

Published
2017
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3. Videreudvikling af model for metaller i vandløbsvand:MetalStat

Author

Sørensen, Peter B., Damgaard, Christian F., Bjerg, Poul L., Andersen, Hans E., Holm, Peter E., Bak, Jesper L., Rasmussen, Dorte, Kjeldgaard, Ane, Sørensen, Peter B., Damgaard, Christian F., Bjerg, Poul L., Andersen, Hans E., Holm, Peter E., Bak, Jesper L., Rasmussen, Dorte, and Kjeldgaard, Ane

Abstract

Denne rapport indgår i et større arbejde under Miljøstyrelsen med udvikling af modeller til estimering af koncentrationer af miljøfarlige forurenende stoffer i overfladevand. Udgangspunktet i denne rapport er en pilot version af en statistisk model (MetalStat) for landsdækkende forekomst af metaller i vandløbsvand. Rapporten tager således udgangspunkt i afrapportering af MetalStats principper givet i Sørensen et al., 2022. Modellen er sat op, så metalkoncentrationen i vandløbet regnes for at være bestemt af det ID15 opland, som målestationen er placeret i, hvor et ID15 opland har en varierende udstrækning på typisk 10-15 km2. Opgaven for 2022 er at få pilotudgaven af MetalStat valideret og modnet, så den kan indgå i Miljøstyrelsens forvaltning. Af regnetekniske grunde var det kun muligt i 2021 at afslutte beregninger for de tre metaller bly, cadmium og nikkel, selvom der også er omfattende data på kobber og zink, Sørensen et al., 2022. Dette skyldtes, at der er blevet justeret på modellens struktur helt hen til udgangen af 2021, og der stilles større krav til beregningstid med fem metaller end med tre. I denne rapport er MetalStat derfor udvidet med kobber og zink, så den behandler fem metaller i en multivariat statistik model, der udnytter korrelationen med metallerne i bestræbelsen på at levere en optimal anvendelse af moniteringsdata. For de oplande, hvor metalkoncentrationen er blevet målt, anvendes de estimerede latente variable, som modellerer middelværdien af koncentrationen på en logskala. Denne middelværdi på log skala kan omregnes til mediankoncentrationen, hvilket betyder at hovedresultatet fra MetalStat er prædiktioner af mediankoncentrationer. For de oplande, der ikke har målinger laver MetalStat prædiktioner af mediankoncentrationen, med tilhørende usikkerhedsinterval, og er således en model, der dækker hele landet. De estimerede latente variabler er tilpasset til en multinormal målemodel og renset for effekten af år, men e

Published
2023

12. NORMA-Gene: A simple and robust method for qPCR normalization based on target gene data

Author

Sørensen Jesper G, Krogh Paul, Sørensen Peter B, and Heckmann Lars-Henrik

Subjects
Computer applications to medicine. Medical informatics, R858-859.7, Biology (General), QH301-705.5
Abstract

Abstract Background Normalization of target gene expression, measured by real-time quantitative PCR (qPCR), is a requirement for reducing experimental bias and thereby improving data quality. The currently used normalization approach is based on using one or more reference genes. Yet, this approach extends the experimental work load and suffers from assumptions that may be difficult to meet and to validate. Results We developed a data driven normalization algorithm (NORMA-Gene). An analysis of the performance of NORMA-Gene compared to reference gene normalization on artificially generated data-sets showed that the NORMA-Gene normalization yielded more precise results under a large range of parameters tested. Furthermore, when tested on three very different real qPCR data-sets NORMA-Gene was shown to be best at reducing variance due to experimental bias in all three data-sets compared to normalization based on the use of reference gene(s). Conclusions Here we present the NORMA-Gene algorithm that is applicable to all biological and biomedical qPCR studies, especially those that are based on a limited number of assayed genes. The method is based on a data-driven normalization and is useful for as little as five target genes comprising the data-set. NORMA-Gene does not require the identification and validation of reference genes allowing researchers to focus their efforts on studying target genes of biological relevance.

Published
2011
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21. Conceptual modeling for identification of worst case conditions in environmental risk assessment of nanomaterials using nZVI and C60 as case studies

Author

Grieger, Khara Deanne, Hansen, Steffen Foss, Sørensen, Peter B., Baun, Anders, Grieger, Khara Deanne, Hansen, Steffen Foss, Sørensen, Peter B., and Baun, Anders

Abstract

Conducting environmental risk assessment of engineered nanomaterials has been an extremely challenging endeavor thus far. Moreover, recent findings from the nano-risk scientific community indicate that it is unlikely that many of these challenges will be easily resolved in the near future, especially given the vast variety and complexity of nanomaterials and their applications. As an approach to help optimize environmental risk assessments of nanomaterials, we apply the Worst-Case Definition (WCD) model to identify best estimates for worst-case conditions of environmental risks of two case studies which use engineered nanoparticles, namely nZVI in soil and groundwater remediation and C60 in an engine oil lubricant. Results generated from this analysis may ultimately help prioritize research areas for environmental risk assessments of nZVI and C60 in these applications as well as demonstrate the use of worst-case conditions to optimize future research efforts for other nanomaterials. Through the application of the WCD model, we find that the most probable worst-case conditions for both case studies include i) active uptake mechanisms, ii) accumulation in organisms, iii) ecotoxicological response mechanisms such as reactive oxygen species (ROS) production and cell membrane damage or disruption, iv) surface properties of nZVI and C60, and v) acute exposure tolerance of organisms. Additional estimates of worst-case conditions for C60 also include the physical location of C60 in the environment from surface run-off, cellular exposure routes for heterotrophic organisms, and the presence of light to amplify adverse effects. Based on results of this analysis, we recommend the prioritization of research for the selected applications within the following areas: organism active uptake ability of nZVI and C60 and ecotoxicological response end-points and response mechanisms including ROS production and cell membrane damage, full nanomaterial characterization taking into account

Published
2011

23. Monte Carlo (Tier 2) uncertainty analysis of Danish Greenhouse gas emission inventory

Author

Fauser, Patrik, primary, Sørensen, Peter B., additional, Nielsen, Malene, additional, Winther, Morten, additional, Plejdrup, Marlene S., additional, Hoffmann, Leif, additional, Gyldenkærne, Steen, additional, Mikkelsen, Mette Hjorth, additional, Albrektsen, Rikke, additional, Lyck, Erik, additional, Thomsen, Marianne, additional, Hjelgaard, Katja, additional, and Nielsen, Ole-Kenneth, additional

Published
2011
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26. Developing European conservation and mitigation tools for pollination services: approaches of the STEP (Status and Trends of European Pollinators) project

Author

Potts, Simon G, primary, Biesmeijer, Jacobus C, additional, Bommarco, Riccardo, additional, Felicioli, Antonio, additional, Fischer, Markus, additional, Jokinen, Pekka, additional, Kleijn, David, additional, Klein, Alexandra-Maria, additional, Kunin, William E, additional, Neumann, Peter, additional, Penev, Lyubomir D, additional, Petanidou, Theodora, additional, Rasmont, Pierre, additional, Roberts, Stuart P M, additional, Smith, Henrik G, additional, Sørensen, Peter B, additional, Steffan-Dewenter, Ingolf, additional, Vaissière, Bernard E, additional, Vilà, Montserrat, additional, Vujić, Ante, additional, Woyciechowski, Michal, additional, Zobel, Martin, additional, Settele, Josef, additional, and Schweiger, Oliver, additional

Published
2011
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48. Developing decision support based on field data and partial order theory.

Author

Brüggemann, Rainer, Carlsen, Lars, Sørensen, Peter B., Lerche, Dorte B., and Thomsen, Marianne

Abstract

The corner stone in the development of decision support systems is to secure that the partial ordering of descriptors does reflect reality. The similarity between descriptor ranking and field scale data ranking is thus highly critical and this chapter shows how to establish this linkage. The partial order technique is used as a robust and non-parametric similarity quantification method and illustrated using monitoring data of pesticide findings in streams of Denmark. The approach has a general appeal where the consequence of false positives (accidentally identification of a similarity) is critical and/or only rough knowledge exist about relations between the data sets that are going to be analysed for similarity. A simple and transparent mapping of a correlation profile is possible and the software named Po Correlation supports the principle described in this chapter. The principle is an extension of the conventional Kendalls Tau that is modified to include ordering using more than two data sets simultaneously and thus being a kind of a multi-variate rank correlation analysis. The multi-variate nature opens up for several measures of discordance that shows different aspects of discrepancy between the data set. A graphical display using Hasse diagrams of respectively concordant and discordant rankings shows how individual objects are respectively correlated and anti-correlated with regard to all the other objects. A testing algorithm using randomized data sets are included in order to test for statistically significance of both similarity and discrepancy. [ABSTRACT FROM AUTHOR]

Published
2006
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49. Taxation of the self-employed under a dual income tax

Author

Mutén, Leif, Sørensen, Peter B., Hagen, Kåre P., Genser, Bernd, Hagen, Kåre Petter, Sørensen, Peter Birch, Mutén, Leif, Sørensen, Peter B., Hagen, Kåre P., Genser, Bernd, Hagen, Kåre Petter, and Sørensen, Peter Birch

Published
1996

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