| 1. |
- Ahlberg, Erik, et al.
(författare)
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"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 2. |
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| 3. |
- Lindström, Johan, et al.
(författare)
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Background and Foreground Modeling Using an Online EM Algorithm
- 2006
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Ingår i: IEEE International Workshop on Visual Surveillance. ; VS2006, s. 9-16
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Konferensbidrag (refereegranskat)abstract
- A novel approach to background/foreground segmentation using an online EM algorithm is presented. The method models each layer as a Gaussian mixture, with local, per pixel, parameters for the background layer and global parameters for the foreground layer, utilising information from the entire scene when estimating the foreground. Additionally, the online EM algorithm uses a progressive learning rate where the relative update speed of each Gaussian component depends on how often the component has been observed. It is shown that the progressive learning rate follows naturally from introduction of a forgetting factor in the log-likelihood. To reduce the number of mixture components similar foreground components are merged using a method based on the Kullback-Leibler distance. A bias is introduced in the variance estimates to avoid the known problem of singularities in the log-likelihood of Gaussian mixtures when the variance tends to zero. To allow a decoupling of the learning rate of the Gaussian components and the speed at which stationary objects are incorporated into the background a CUSUM detector is used instead of the prevailing method that uses the ratio of prior probability to standard deviation. The algorithm is scale invariant and its properties on gray-scale and RGB videos, as well as on output from an edge detector, is compared to that of another algorithm. Especially for the edge detector video performance increases dramatically.
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| 4. |
- Lindström, Johan, et al.
(författare)
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Influence of solar zenith angles on observed trends in the NOAA/NASA 8-km Pathfinder normalized difference vegetation index over the African Sahel
- 2006
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Ingår i: International Journal of Remote Sensing. - : Informa UK Limited. - 1366-5901 .- 0143-1161. ; 27:9-10, s. 1973-1991
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Tidskriftsartikel (refereegranskat)abstract
- The strong systematic change in solar zenith angles (SZA) due to annual orbital drift of the NOAA satellites has raised the suspicion of the influence of residual illumination on the calibrated normalized difference vegetation index (NDVI) derived from the Pathfinder AVHRR Land (PAL) database. The aim of this work is to analyse if trends in AVHRR NDVI from 1982 to 2000 over the Sahel region in Africa depend on variations in SZA. The analysis uses both ordinary least squares regression and cointegration to analyse possible linear dependencies between NDVI and SZA on a per satellite basis. Tests for integration and cointegration fail to find any significant evidence for either. This, together with the ability of simple deterministic models to explain primarily SZA constitutes evidence against integration and cointegration, indicating that linear relationships can be examined using ordinary linear regression. Regression gives no consistent relationship between NDVI and SZA and the explanatory power (R 2) of the regression is low (on average 0.08). However there is some evidence for downward bias in NDVI due to nonlinear interactions between NDVI and SZA when SZA is large (>= 80 degrees) leading to the conclusion that PAL data from the year 2000 should not be used for analyses in these environments.
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| 5. |
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| 6. |
- Anderhag, Per, et al.
(författare)
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Syften och tillfälligheter i högstadie- och gymnasielaborationen : en studie om hur elever handlar i relation till aktivitetens mål
- 2014
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Ingår i: NorDiNa. - : University of Oslo Library. - 1504-4556 .- 1894-1257. ; 10:1, s. 63-76
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Tidskriftsartikel (refereegranskat)abstract
- Purposes and contingencies in the lower and upper secondary school labStudies have shown that students’ awareness of the goals and purposes of the laboratory activity is important for their possibility to participate in and learn from the activity. While practical activities often have been considered to be a central part of science education, relatively few studies have examined laboratory work in situ. In this paper we addressed these issues by examining (a) what purposes are distinguished when students’ work with a laboratory assignment and (b) how these purposes are made continuous with the teacher’s aim with the assignment. The data was based on classroom observations from two ordinary laboratory settings, one from a chemistry class in lower secondary school and one from a physics class in the natural science programme in upper secondary school. Although both student groups acknowledged their teacher’s intentions with the practical and could act towards the more student centered purposes of the activity, e.g. describe what happens with the copper and measure the speed of a small vessel respectively, there were differences regarding the possibilities the students had to act toward the activity’s final aim. The results showed that these factors can be referred to the amount of purposes introduced by the teacher as well as those that arose because of contingences, and the connection of these purposes to students’ prior experiences.
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| 7. |
- Asplund, Maria, 1978-, et al.
(författare)
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Biocompatibility of PEDOT/biomolecular composites intended for neural communication electrodes
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Annan publikation (populärvet., debatt m.m.)abstract
- Electrodes of the conjugated polymer poly(3,4-ethylene dioxythiophene) (PEDOT) have been shown to possess very attractive electrochemical properties for functional electrical stimulation (FES) or recording in the nervous system. Biomolecules already present in nervous tissue, added as counter ions in PEDOT electropolymerisation, could be a route to further improve the biomaterial properties of PEDOT, eliminating the need of surfactant counter ions like docedyl benzene sulphonate (DBS) or polystyrene sulphonate (PSS) in the polymerisation process. Such PEDOT/biomolecular composites using heparin, or hyaluronic acid, have been electrochemically investigated in a previous study and have been shown to retain the attractive electrochemical properties already proven for PEDOT:PSS. The aim of the present study is to evaluate biocompatibility of these PEDOT/biomolecular composites in vitro and also evaluate PEDOT:heparin biocompatibility in cortical tissue in vivo. Hereby, we also aim to identify a suitable test protocol, that can be used in future evaluations when further material developments are made. Material toxicity was first tested on cell lines, both through a standardised agarose overlay assay on L929 fibroblasts, and through elution tests on human neuroblastoma SH-SY5Y cells. Subsequently, a biocompatibility in vivo test was performed using PEDOT:heparin coated platinum probes implanted in the cerebral cortex of Sprague-Dawley rats. Tissue was collected at three weeks and six weeks of implantation and evaluated by immunohistochemistry. No cytotoxic response was seen to any of the PEDOT:biomolecular composites tested here. Furthermore, elution tests were found to be a practical and effective way of screening materials for toxicity and had a clear advantage over the agarose overlay assay, which was difficult to apply on other cell types than fibroblasts. Elution tests would therefore be recommendable as a screening method, at all stages of material development. In the in vivo tests, the stiffness of the platinum substrate was a significant problem, and extensive glial scarring was seen in most cases irrespective of implant material. However, quantification of immunological response through distance measurements from implant site to closest neuron, and counting of macrophage densities in proximity to polymer surface, was comparable to those of platinum controls. These results indicate that PEDOT:heparin surfaces were as compatible with cortical tissue as pure platinum controls.
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| 8. |
- Daoud, Fatima, et al.
(författare)
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Role of smooth muscle YAP and TAZ in protection against phenotypic modulation, inflammation, and aneurysm development
- 2022
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Ingår i: Biochemical Pharmacology. - : Elsevier BV. - 0006-2952. ; 206
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Forskningsöversikt (refereegranskat)abstract
- A ruptured arterial aneurysm, especially in the aorta, represents one of the most acute and mortal conditions encountered in clinical medicine. Population-based screening in elderly men, treatment of risk factors, such as hypertension, and endovascular or open repair of rupture-prone lesions, represent cornerstones in management. Surgical repair has a sizeable effect on life-expectancy, but medical therapy that retards aneurysm growth still represents a considerable and unmet clinical need. In the current review we survey recent findings implicating the mechano-responsive transcriptional co-activators YAP and TAZ in protection from aneurysm development. Arteries from mouse mutants that lack YAP and TAZ in vascular smooth muscle respond inadequately to mechanical stimulation, and they develop aneurysms characterized by elastin fragmentation, proteoglycan infiltration, and severe inflammation at breathtaking speed. This seems to be due, at least in part, to unscheduled activation of STING (stimulator of interferon genes), an arm of innate immunity that responds to double-stranded DNA in the cytoplasm. YAP and TAZ protect from STING activation by securing nuclear integrity. These novel insights suggest unanticipated medical therapies for sporadic and genetic aneurysms alike, involving inhibition of kinases in the Hippo pathway using small molecules, or inhibition of STING signaling itself. Translation of these novel findings into clinical therapies now represents an important priority.
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