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- Björklund, J., et al.
(författare)
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Scientific Merits and Analytical Challenges of Tree-Ring Densitometry
- 2019
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Ingår i: Reviews of geophysics. - 8755-1209 .- 1944-9208. ; 57:4, s. 1224-1264
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Forskningsöversikt (refereegranskat)abstract
- X-ray microdensitometry on annually resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular, and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh long-standing wisdom but also provide new insights. Key outcomes include (i) a demonstration of the need for mass/volume-based recalibration to accurately estimate average ring density; (ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density data sets for climate reconstructions; and (iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate futureinter-comparability and interpretations for global change research.
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- Björklund, Jesper, 1979, et al.
(författare)
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Scientific Merits and Analytical Challenges ofTree-Ring Densitometry
- 2019
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Ingår i: Reviews of Geophysics. - : American Geophysical Union (AGU). - 8755-1209 .- 1944-9208. ; 57:4, s. 1224-1264
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Tidskriftsartikel (refereegranskat)abstract
- X-ray microdensitometry on annually resolved tree-ring samples has gained an exceptional position in last-millennium paleoclimatology through the maximum latewood density (MXD) parameter, but also increasingly through other density parameters. For 50 years, X-ray based measurement techniques have been the de facto standard. However, studies report offsets in the mean levels for MXD measurements derived from different laboratories, indicating challenges of accuracy and precision. Moreover, reflected visible light-based techniques are becoming increasingly popular, and wood anatomical techniques are emerging as a potentially powerful pathway to extract density information at the highest resolution. Here we review the current understanding and merits of wood density for tree-ring research, associated microdensitometric techniques, and analytical measurement challenges. The review is further complemented with a careful comparison of new measurements derived at 17 laboratories, using several different techniques. The new experiment allowed us to corroborate and refresh "long-standing wisdom" but also provide new insights. Key outcomes include (i) a demonstration of the need for mass/volume-based recalibration to accurately estimate average ring density; (ii) a substantiation of systematic differences in MXD measurements that cautions for great care when combining density data sets for climate reconstructions; and (iii) insights into the relevance of analytical measurement resolution in signals derived from tree-ring density data. Finally, we provide recommendations expected to facilitate futureinter-comparability and interpretations for global change research.
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- Hoffmann, Mikael, et al.
(författare)
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Guiding principles for the use of knowledge bases and real-world data in clinical decision support systems : report by an international expert workshop at Karolinska Institutet
- 2020
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Ingår i: Expert Review of Clinical Pharmacology. - : Taylor & Francis. - 1751-2433 .- 1751-2441. ; 13:9, s. 925-934
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Technical and logical breakthroughs have provided new opportunities in medicine to use knowledge bases and large-scale clinical data (real-world) at point-of-care as part of a learning healthcare system to diminish the knowledge-practice gap. Areas covered The article is based on presentations, discussions and recommendations from an international scientific workshop. Value, research needs and funding avenues of knowledge bases and access to real-world data as well as transparency and incorporation of patient perspectives are discussed. Expert opinion Evidence-based, publicly funded, well-structured and curated knowledge bases are of global importance. They ought to be considered as a public responsibility requiring transparency and handling of conflicts of interest. Information has to be made accessible for clinical decision support systems (CDSS) for healthcare staff and patients. Access to rich and real-world data is essential for a learning health care ecosystem and can be augmented by data on patient-reported outcomes and preferences. This field can progress by the establishment of an international policy group for developing a best practice guideline on the development, maintenance, governance, evaluation principles and financing of open-source knowledge bases and handling of real-world data.
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- Horger, B A, et al.
(författare)
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Neurturin exerts potent actions on survival and function of midbrain dopaminergic neurons
- 1998
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Ingår i: The Journal of Neuroscience. - 1529-2401. ; 18:13, s. 4929-4937
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Tidskriftsartikel (refereegranskat)abstract
- Glial cell line-derived neurotrophic factor (GDNF) exhibits potent effects on survival and function of midbrain dopaminergic (DA) neurons in a variety of models. Although other growth factors expressed in the vicinity of developing DA neurons have been reported to support survival of DA neurons in vitro, to date none of these factors duplicate the potent and selective actions of GDNF in vivo. We report here that neurturin (NTN), a homolog of GDNF, is expressed in the nigrostriatal system, and that NTN exerts potent effects on survival and function of midbrain DA neurons. Our findings indicate that NTN mRNA is sequentially expressed in the ventral midbrain and striatum during development and that NTN exhibits survival-promoting actions on both developing and mature DA neurons. In vitro, NTN supports survival of embryonic DA neurons, and in vivo, direct injection of NTN into the substantia nigra protects mature DA neurons from cell death induced by 6-OHDA. Furthermore, administration of NTN into the striatum of intact adult animals induces behavioral and biochemical changes associated with functional upregulation of nigral DA neurons. The similarity in potency and efficacy of NTN and GDNF on DA neurons in several paradigms stands in contrast to the differential distribution of the receptor components GDNF Family Receptor alpha1 (GFRalpha1) and GFRalpha2 within the ventral mesencephalon. These results suggest that NTN is an endogenous trophic factor for midbrain DA neurons and point to the possibility that GDNF and NTN may exert redundant trophic influences on nigral DA neurons acting via a receptor complex that includes GFRalpha1.
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- Jensen, I-B, et al.
(författare)
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The AHA-study: Implementing evidence based measueres for retaining workability at work sites : Effects on lifestyle, workability and firm productivity. 9th International Congress of Behavioral Medicine. Bangkok, Thailand, Nov 29-Dec 2, 2006
- 2006
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Jensen IB, Bergstrom G, Bjorklund C, Fried I, Lisspers J, Nathell L, Hermansson U, Roos P, Bodin L, the AHAstudy group (2006). The AHA-study: Implementing evidence based measueres for retaining workability at work sites - Effcets on lifestyle, workability and firm productivity. Presented at the 9th International Congress of Behavioral Medicine. Bangkok, Thailand, Nov 29-Dec 2, 2006.
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- Juter, Kristina, et al.
(författare)
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Mathematics and physics at upper secondary school : an analysis of two lectures
- 2021
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Ingår i: Sustainable mathematics education in a digitalized world. - Göteborg : Nationellt centrum för matematikutbildning (NCM). ; , s. 264-264
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Bokkapitel (populärvet., debatt m.m.)abstract
- A physics lecture and a mathematics lecture, by the same teacher and partly the same students, were studied at upper secondary school. Both lectures covered ordinary differential equations. The main aim of the present paper was to investigate the teacher’s different and similar ways to handle related mathematical content in the two school subjects. The findings show a structural use of mathematics with an analytical approach in mathematics and an applied approach in relation to formulas in physics. This study is part of a larger study about mathematics in physics education funded by the Swedish research council.
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