| 1301. |
- Kumar, Sandeep, et al.
(författare)
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Magnetic polarons and large negative magnetoresistance in GaAs nanowires implanted with Mn ions
- 2013
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Ingår i: Nano letters (Print). - Washington, United States : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 13:11, s. 5079-5084
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Tidskriftsartikel (refereegranskat)abstract
- We report on low-temperature magnetotransport and SQUID measurements on heavily doped Mn-implanted GaAs nanowires. SQUID data recorded at low magnetic fields exhibit clear signs of the onset of a spin-glass phase with a transition temperature of about 16 K. Magnetotransport experiments reveal a corresponding peak in resistance at 16 K and a remarkably large negative magnetoresistance, reaching 40 % at 1.6 K and 8 T. The negative magnetoresistance decreases at elevated temperatures and vanishes at about 100 K. We interpret our transport data in terms of spin-dependent hopping in a complex magnetic nanowire landscape of magnetic polarons forming a paramagnetic/spin-glass phase.
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| 1302. |
- Kuosmanen, Niina, et al.
(författare)
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The role of climate, forest fires and human population size in Holocene vegetation dynamics in Fennoscandia
- 2018
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Ingår i: Journal of Vegetation Science. - : Wiley-Blackwell. - 1100-9233 .- 1654-1103. ; 29:3, s. 382-392
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Tidskriftsartikel (refereegranskat)abstract
- QuestionsWe investigated the changing role of climate, forest fires and human population size in the broad-scale compositional changes in Holocene vegetation dynamics before and after the onset of farming in Sweden (at 6,000cal yr BP) and in Finland (at 4,000calyr BP). LocationSouthern and central Sweden, SW and SE Finland. MethodsHolocene regional plant abundances were reconstructed using the REVEALS model on selected fossil pollen records from lakes. The relative importance of climate, fires and human population size on changes in vegetation composition was assessed using variation partitioning. Past climate variable was derived from the LOVECLIM climate model. Fire variable was reconstructed from sedimentary charcoal records. Estimated trend in human population size was based on the temporal distribution of archaeological radiocarbon dates. ResultsClimate explains the highest proportion of variation in vegetation composition during the whole study period in Sweden (10,000-4,000cal yr BP) and in Finland (10,000-1,000cal yr BP), and during the pre-agricultural period. In general, fires explain a relatively low proportion of variation. Human population size has significant effect on vegetation dynamics after the onset of farming and explains the highest variation in vegetation in S Sweden and SW Finland. ConclusionsMesolithic hunter-gatherer populations did not significantly affect vegetation composition in Fennoscandia, and climate was the main driver of changes at that time. Agricultural communities, however, had greater effect on vegetation dynamics, and the role of human population size became a more important factor during the late Holocene. Our results demonstrate that climate can be considered the main driver of long-term vegetation dynamics in Fennoscandia. However, in some regions the influence of human population size on Holocene vegetation changes exceeded that of climate and has a longevity dating to the early Neolithic.
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| 1303. |
- Kwiatkowski, Adam, et al.
(författare)
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Galvanomagnetic methods of Curie temperature determination in (Ga,Mn)As
- 2018
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier. - 0304-8853 .- 1873-4766. ; 467, s. 120-128
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Tidskriftsartikel (refereegranskat)abstract
- We critically discuss various experimental methods to determine Curie temperature T-C of (Ga,Mn)As thin layers or other conducing magnetic materials by means of electric charge transport measurements. They all base on the influence of sample magnetization on the magnetoresistivity tensor <(rho)overcap>and are an alternative to the method based upon an analysis of the temperature derivative of the sample resistance (Novak a al., 2008). These methods can be applied even when standard SQUID magnetometers are difficult or impossible to use - for example for extremely small samples or in the case of experiments performed at very specific physical conditions, e.g. at high hydrostatic pressure inside the clamp cell. We show that the use of the so called Arrott plot prepared with the use of high magnetic field isotherms rho(xx)(H-0), rho(x)y(H-0) (H-0 - external magnetic field) may lead to substantial (of the order of 10 K) divergence of the obtained T-c values depending on the assumptions which are necessary to make in this case and depending on the direction of a magnetic anisotropy easy axis. We also propose a number of ways how to obtain, basing on low magnetic field isotherms rho(xx)(H-0), rho(xy)(H-0) clear and characteristic features which are closely related to the ferromagnetic-paramagnetic phase transition.
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| 1304. |
- Kyhn, Maria Voss, et al.
(författare)
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Delayed administration of glial cell line-derived neurotrophic factor (GDNF) protects retinal ganglion cells in a pig model of acute retinal ischemia
- 2009
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Ingår i: Experimental Eye Research. - : Elsevier BV. - 0014-4835 .- 1096-0007. ; 89:6, s. 1012-1020
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Tidskriftsartikel (refereegranskat)abstract
- This study investigates whether intravitreal administration of glial cell line-derived neurotrophic factor (GDNF) enhances survival of NeuN positive retinal cells in a porcine model of retinal ischemia. 16 pigs were subjected to an ischemic insult where intraocular pressure was maintained at 5 mmHg below mean arterial blood pressure for 2 h. The mean IOP during the ischemic insult was 79.5 mmHg (s.e.m. 2.1 mmHg, n = 15). Three days after the insult the pigs received an intravitreal injection of GDNF microspheres or blank microspheres. The pigs were evaluated by way of multifocal electroretinography (mfERG), quantification of NeuN positive cells and evaluation of the degree of retinal perivasculitis and inflammation 6 weeks after the insult. In the post-injection eyes (days 14, 28 and 42), the ratios of the iN1 and the iP2 amplitudes were 0.10 (95% CI: 0.05-0.15) and 0.09 (95% CI: 0.04-0.16) in eyes treated with blank microspheres, and 0.24 (95% CI: 0.18-0.32) and 0.23 (95% CI: 0.15-0.33) in eyes treated with GDNF microspheres. These differences were statistically significant (P < 0.05). The number of NeuN positive cells in the area of the visual streak area was significantly higher in eyes injected with GDNF microspheres compared to eyes injected with blank microspheres. In eyes injected with GDNF microspheres the ganglion cell count was 9.5/field (s.e.m.: 2.1, n = 8), in eyes injected with blank microspheres it was 3.5/field (s.e.m.: 1.2, n = 7). This difference was statistically significant (P < 0.05). There was also a significant difference (P < 0.01) in the degree of perivasculiitis between GDNF treated eyes (median perivasculitis score 1.5) and blank treated eyes (median perivasculitis score 3.0). In conclusion, injection of GDNF microspheres 3 days after an ischemic insult results in functional and morphological rescue of NeuN positive cells in a porcine model of acute ocular ischemia. (C) 2009 Elsevier Ltd. All rights reserved.
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| 1305. |
- Källkvist, Marie, 1967-, et al.
(författare)
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Alltid engelska i engelskundervisningen? : Flerspråkiga elevers perspektiv
- 2018
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Ingår i: Leda lärande 2018. - Stockholm : Stockholms stad.
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Konferensbidrag (populärvet., debatt m.m.)abstract
- Ska elevers olika modersmål samt skolspråket svenska användas på engelsklektioner? Detta är den övergripande frågeställningen i forskningsprojektet Flerspråkiga praktiker – en resurs i engelskundervisningen? som är finansierat av Vetenskapsrådet. I föreläsningen presenteras forskning om undervisning och lärande i engelska som ligger till grund för projektet samt projektets första resultat. Dessa belyser flerspråkiga elevers och deras lärares attityder och praktiker gällande användningen av olika språk för att stödja lärande och delaktighet i engelskundervisningen.
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| 1306. |
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| 1307. |
- Källkvist, Marie, 1967-, et al.
(författare)
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Discursive mechanisms and human agency in language policy formation : negotiating bilingualism and parallel language use at a Swedish university
- 2016
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Ingår i: International Journal of Bilingual Education and Bilingualism. - : Taylor & Francis. - 1367-0050 .- 1747-7522. ; 19:1, s. 1-17
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Tidskriftsartikel (refereegranskat)abstract
- n the wake of the enactment of Sweden's Language Act in 2009 and in the face of the growing presence of English, Swedish universities have been called upon by the Swedish Higher Education Authority to craft their own language policy documents. This study focuses on the discursive negotiation of institutional bilingualism by a language policy committee at one Swedish university during the process of developing a draft language policy. Following an ethnographic/discourse analytic orientation to language policy and planning research, data were collected during language policy committee meetings at the university. Using nexus analysis, circulating discourses are mapped and analyzed, with a specific focus on how these discourses were negotiated through mediated actions during committee meeting interaction and then entextualized in a draft policy. Analysis reveals how ‘bilingualism’ became reinterpreted as ‘parallel language use,’ a concept developed and used in Nordic language planning over the past 15 years. Analysis further shows how committee members negotiated the meaning of parallel language use and the processes of resemiotization that took place as discourses from other sociolinguistic scales entered into the committee's discussion and writing. In all, the study highlights discursive mechanisms of language planning and the interplay of social actors and texts.
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| 1308. |
- Källkvist, Marie, 1967-, et al.
(författare)
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English Only in Multilingual Classrooms? : A study of students' self-reported practices and attitudes
- 2019
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Ingår i: AAAL conference Atlanta 2019. - Atlanta, GA : American Association For Applied Linguistics.
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Konferensbidrag (refereegranskat)abstract
- A pressing issue in multilingual education is when to draw on students’ multilingual repertoires to enhance learning and promote equity (Cummins 2017; Kramsch 2009). Classroom research in L2 learning supports multilingual/translanguaging practices (e.g. Lee & Macaro 2013; Zhang 2018), but much of this research involves participants who had acquired the same L1 prior to having classroom exposure to English (L2). The present study breaks new ground by focusing on multilingual participants with different L1s: Participants are either simultaneous bilinguals of Swedish (the majority language) and a heritage language (such as Somali), or L1-speakers of their heritage language, learning both Swedish and English in a high school in Sweden. Triangulated qualitative data were collected in 2018 in two groups of students (age 14-15): ethnographic observation (14 English lessons), student questionnaires and interviews (18 students) and an interview with their teacher. With an analytical framework rooted in bilingualism/multilingualism (Baker & Wright 2017), concepts such as ‘language dominance’, ‘age of onset’, ‘heritage language’, ‘majority language’ and ‘school language’ were applied in qualitative analysis. As a basis for studying students’ attitudes, the classroom observations revealed that the teacher used mainly English; Swedish was restricted to metalinguistic explanations, translations of vocabulary, and information pertaining to task requirements and grading criteria. Student interviews revealed that the majority stated that they benefit from their teacher’s explanations in both English and Swedish, of Swedish translation equivalents, and of task and grading information verbalized in both English and Swedish. Students with lower proficiency in English expressed a greater need for Swedish. Students who were dominant in their heritage language expressed a need to draw on the heritage language, although not necessarily in the classroom. An important implication is the value to students of certain information being provided both in the target language (English) and in the school language (Swedish).
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| 1309. |
- Källkvist, Marie, 1967-, et al.
(författare)
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English-Swedish Translanguaging in Multilingual Secondary English Classrooms : A Study of Students' Attitudes
- 2019
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Ingår i: The third Swedish Translanguaging Conference. - Växjö : Linnaeus University. ; , s. 48-49
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Konferensbidrag (refereegranskat)abstract
- A pressing issue in multilingual education is when to draw on students’ entire multilingual repertoires to enhance learning and promote equity (Cummins 2017; Kramsch 2009). Classroom research on the learning of L2 English supports multilingual/translanguaging practices (Lee & Macaro 2013; Zhang 2018), but much of this research involves students who had acquired the same L1 prior to having classroom exposure to English (L2). This study breaks new ground by focusing on multilingual students with different L1s: They are either simultaneous bilinguals of Swedish (the majority language) and a minority language (such as Somali), or L1-speakers of the minority language, learning both Swedish and English in a secondary school in Sweden. We collected triangulated qualitative data in 2018 in two groups of students (age 14-15): ethnographic observation (14 English lessons), student interviews (N=18) and an interview with their teacher. With an analytical framework rooted in bilingualism/multilingualism (Baker & Wright 2017), concepts such as ‘language dominance’, ‘age of onset’, ‘heritage language’, ‘majority language’ and ‘school language’ were applied in qualitative analysis. The classroom observation data revealed that the teacher, being a Swedish-English bilingual, used mainly English when teaching; Swedish was used for metalinguistic explanations, translations of vocabulary, and information pertaining to task requirements and grading criteria. In the interviews, the majority reported that they benefit from their teacher’s English-Swedish translanguaging practices, particularly from task and grading information being verbalized in both English and Swedish. Students with lower proficiency in English expressed a greater need for Swedish. Students dominant in their heritage language expressed a need to draw on the heritage language, mainly when doing their homework rather than in the classroom. An important implication is that the students placed value in receiving information about task requirements and grading criteria in both the target language (English) and in the school language (Swedish).
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| 1310. |
- Källkvist, Marie, 1967-, et al.
(författare)
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Interaction in the multilingual classroom
- 2022
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Ingår i: The Cambridge Handbook of Intercultural Pragmatics. - Cambridge : Cambridge University Press. - 9781108884303 - 9781108839532 ; , s. 836-868
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Bokkapitel (refereegranskat)abstract
- Classroom language ecologies are increasingly diverse as a result of mobility, migration, and information technology. In these spaces, interlocutors may draw upon shared linguistic and cultural resources but also bring in others. Prime examples are additional-language (AL) classrooms, where there is a shared target language, but where students may have different first languages from their classmates and teacher. In this chapter, we review empirical research on interaction in multilingual classrooms in approaches such as ethnography, translanguaging, and conversation analysis (CA), and discuss methods and findings in relation to the growing field of intercultural pragmatics (IP). Additionally, we offer an empirical illustration from video ethnography research in multilingual English AL classrooms in Sweden. With a CA approach, we demonstrate how a group of students participating in a vocabulary game manage an instance of diverging understandings of an English word. We show how, in resolving this interactional trouble, participants draw on the target language English and the societal/school language Swedish, and we discuss the observations in light of the IP concepts of salience and common ground. Finally, we argue that classroom studies detailing social actors’ language repertoires by using audiovisual data are essential in advancing our understanding of multilingual AL classrooms.
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