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- Larsson, Bo
(author)
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I bild och ord – en verkstadsberättelse
- 2005
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In: Bebyggelsehistorisk tidskrift. - : Föreningen Bebyggelsehistorisk tidskrift. - 0349-2834 .- 2002-3812. ; :50, s. 32-41
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Journal article (peer-reviewed)
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| 3. |
- Berghäuser, Gunnar, 1983, et al.
(author)
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Optical fingerprint of dark 2p-states in transition metal dichalcogenides
- 2017
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In: 2D Materials. - : IOP Publishing. - 2053-1583. ; 4:1
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Journal article (peer-reviewed)abstract
- Atomically thin transition metal dichalcogenides exhibit a remarkably strong Coulomb interaction. This results in a fascinating many-particle physics including a variety of bright and dark excitonic states that determine optical and electronic properties of these materials. So far, the impact of dark states has remained literally in the dark to a large extent, since a measurement of these optically forbidden states is very challenging. Here we demonstrate a strategy to measure a direct fingerprint of dark states even in standard linear absorption spectroscopy. We present a microscopic study on bright and dark higher excitonic states in the presence of disorder for the exemplary material of tungsten disulfide (WS2). We show that the geometric phase cancels the degeneration of 2s and 2p states and that a significant disorder-induced coupling of these bright and dark states offers a strategy to circumvent optical selection rules. As a proof, we show a clear fingerprint of dark 2p states in the absorption spectrum of WS2. The predicted softening of optical selection rules through exciton-disorder coupling is of general nature and therefore applicable to related two-dimensional semiconductors.
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| 5. |
- Case, Megan, 1976-
(author)
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Language students’ personal learning environments through an activity theory lens
- 2015. - 1
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In: Researching Language Learner Interaction Online: From Social Media to MOOCs. - San Marcos, TX : CALICO. - 9780996316507
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Book chapter (peer-reviewed)abstract
- This chapter illustrates a learner-centric approach to investigating the potential of online resources for language learning. In contrast to studies that look at the use of particular applications, tools, or social media platforms in formal educational contexts, this approach takes into account the totality of the personal learning environments learners create for themselves, intentionally and unintentionally, which may include online vocabulary-training applications, connection with native speakers of the target language through social media, immediate and free access to cultural products such as films, music, and the press, and increasingly ubiquitous machine translation. Using an activity theory framework and questionnaire data, the empirical portion of this chapter illustrates some aspectsof the personal learning environments of adults studying a foreign language at the beginner level and draws the following conclusions: (a) exploring the applicability of technologies for language learning can be done bottom up rather than top down; (b) digital tools do not replace nondigital tools, they complement them; (c) the digital native/digital immigrant distinction (Prensky, 2001; Benini & Murray, 2014) is questionable; (d) learner objectives do not always correspond to curricular objectives; and (e) the lines between language learning and language use can be blurred, and this is enabled in part by technology.
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| 6. |
- Chavan, Swapnil, 1986-
(author)
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Towards new computational tools for predicting toxicity
- 2016
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Doctoral thesis (other academic/artistic)abstract
- The toxicological screening of the numerous chemicals that we are exposed to requires significant cost and the use of animals. Accordingly, more efficient methods for the evaluation of toxicity are required to reduce cost and the number of animals used. Computational strategies have the potential to reduce both the cost and the use of animal testing in toxicity screening. The ultimate goal of this thesis is to develop computational models for the prediction of toxicological endpoints that can serve as an alternative to animal testing. In Paper I, an attempt was made to construct a global quantitative structure-activity relationship (QSAR)model for the acute toxicity endpoint (LD50 values) using the Munro database that represents a broad chemical landscape. Such a model could be used for acute toxicity screening of chemicals of diverse structures. Paper II focuses on the use of acute toxicity data to support the prediction of chronic toxicity. The results of this study suggest that for related chemicals having acute toxicities within a similar range, their lowest observed effect levels (LOELs) can be used in read-across strategies to fill gaps in chronic toxicity data. In Paper III a k-nearest neighbor (k-NN) classification model was developed to predict human ether-a-go-go related gene (hERG)-derived toxicity. The results suggest that the model has potential for use in identifying compounds with hERG-liabilities, e.g. in drug development.
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| 9. |
- Gupta, Anubha, 1974-
(author)
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Role of the Blood-Brain Barrier in Stereoselective Distribution and Delay in H1 Receptor Occupancy of Cetirizine in the Guinea Pig Brain
- 2006
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Doctoral thesis (other academic/artistic)abstract
- Cetirizine, an H1-antihistamine, is prescribed for allergic disorders. It exists as a racemic mixture, with levocetirizine being the active enantiomer. The central nervous system side-effects of H1-antihistamines are caused by their penetration into the brain. In this thesis the plasma pharmacokinetics, transport across the blood-brain barrier (BBB) and H1 receptor occupancy of cetirizine enantiomers was investigated in vivo in guinea pigs. The transport across the BBB was quantified using the microdialysis technique. Stereoselective brain distribution was investigated by measuring both unbound and total concentrations in plasma and brain. The time aspects of the H1 receptor occupancy of levocetirizine was studied in the brain and the periphery.The plasma pharmacokinetics of cetirizine was stereoselective with clearance and volume of distribution of levocetirizine being approximately half that of dextrocetirizine. This was mainly due to the differences in plasma protein binding of the enantiomers. The stereoselectivity in brain distribution indicated by the partition coefficient Kp (total AUC ratio brain to plasma) was caused by stereoselective plasma protein binding. The transport across the BBB measured in this thesis by the unbound partition coefficient Kp,uu (unbound AUC ratio brain to plasma) was the same for the two enantiomers. Binding within the brain was also not significantly different. The H1 receptor occupancy of levocetirizine in brain lagged behind the plasma concentrations whereas it was not delayed with respect to the brain concentrations. This indicates that the delayed brain H1 receptor occupancy of levocetirizine is caused by a slow transport across the BBB.In summary, the results of this thesis emphasize the importance of measuring both the unbound and total concentrations in blood and brain to characterize stereoselective brain distribution. The thesis also emphasize the importance of taking local brain pharmacokinetics into consideration in understanding pharmacokinetic-pharmacodynamic relationships of drugs with central activity.
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