| 1. |
- Kappelhoff, Jan, et al.
(författare)
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Spectroscopic studies on Pr3+ doped YPO4 and LuPO4 upon vacuum ultraviolet (VUV) and synchrotron radiation excitation
- 2022
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Ingår i: Chemical Physics. - : Elsevier BV. - 0301-0104. ; 562
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Tidskriftsartikel (refereegranskat)abstract
- This work concerns the spectroscopic properties of micro- and nanoscale LuPO4:Pr3+ and microscale YPO4:Pr3+ upon excitation by VUV synchrotron radiation at a wide range of energies (5–45 eV) and two different temperatures (7 and 300 K). Both Pr3+ doped host materials show more intense UV-C emission than other Pr3+ phosphors studied earlier at FinEstBeAMS beamline under the same measurement conditions. The various relaxation processes of 5d14f1 → 4f2 interconfigurational transitions of Pr3+ and the difference between both hosts are discussed in detail.
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| 2. |
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| 3. |
- d'Heurle, F. M., et al.
(författare)
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Formation of C54TiSi(2) : Effects of niobium additions on the apparent activation energy
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:12, s. 6409-6415
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Tidskriftsartikel (refereegranskat)abstract
- The formation of C54 TiSi2 using Ti-Nb alloys deposited on polycrystalline Si substrates was studied by means of in situ x-ray diffraction and resistance measurements during temperature ramping. Alloys with Nb contents ranging from 0 to 13.6 at. % were used. The formation temperature of C54 TiSi2 was reduced in the presence of Nb. However, the addition of Nb in Ti did not cause fundamental changes in the evolution of resistance versus temperature. This latter observation suggests that the mechanism for the formation of C54 TiSi2 remained the same in spite of the enhancement effect. For alloys with up to 8 at. % of Nb, the C49 TiSi2 phase formed first, as with pure Ti. When annealing the alloy with 13.6 at. % Nb, neither C49 TiSi2 nor C54 were found in the usual temperature ranges, instead, C40 (Nb,Ti)Si-2 was observed. This phase transformed to C54 (Nb,Ti)Si-2 above 950 degreesC. The apparent activation energy associated with the formation of C54 TiSi2 was obtained by annealing the samples at four different ramp rates from 3 to 27 K/s; it decreased continuously from 3.8 to 2.5 eV with increasing Nb content from 0 to 8 at. %. The apparent activation energy for the formation of C40 (Nb,Ti)Si-2 was found to be 2.6 eV. The possible physical meaning, or lack thereof, of the high activation energies derived from experimental measurements is extensively discussed. A qualitative model is proposed whereby nucleation would be rate controlling in pure TiSi2, and interface motion in samples with 8 at. % Nb.
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| 4. |
- Pirk, Norbert, et al.
(författare)
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Spatial variability of CO2 uptake in polygonal tundra : Assessing low-frequency disturbances in eddy covariance flux estimates
- 2017
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 14:12, s. 3157-3169
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Tidskriftsartikel (refereegranskat)abstract
- The large spatial variability in Arctic tundra complicates the representative assessment of CO2 budgets. Accurate measurements of these heterogeneous landscapes are, however, essential to understanding their vulnerability to climate change. We surveyed a polygonal tundra lowland on Svalbard with an unmanned aerial vehicle (UAV) that mapped ice-wedge morphology to complement eddy covariance (EC) flux measurements of CO2. The analysis of spectral distributions showed that conventional EC methods do not accurately capture the turbulent CO2 exchange with a spatially heterogeneous surface that typically features small flux magnitudes. Nonlocal (low-frequency) flux contributions were especially pronounced during snowmelt and introduced a large bias of -46 gCm-2 to the annual CO22 budget in conventional methods (the minus sign indicates a higher uptake by the ecosystem). Our improved flux calculations with the ogive optimization method indicated that the site was a strong sink for CO2 in 2015 (82 gCm2). Due to differences in light-use efficiency, wetter areas with lowcentered polygons sequestered 47% more CO2 than drier areas with flat-centered polygons. While Svalbard has experienced a strong increase in mean annual air temperature of more than 2K in the last few decades, historical aerial photographs from the site indicated stable ice-wedge morphology over the last 7 decades. Apparently, warming has thus far not been sufficient to initiate strong ice-wedge degradation, possibly due to the absence of extreme heat episodes in the maritime climate on Svalbard. However, in Arctic regions where ice-wedge degradation has already initiated the associated drying of landscapes, our results suggest a weakening of the CO2 sink in polygonal tundra.
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| 5. |
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Den interkulturella blicken i pedagogik : Inte bara goda föresatser
- 2012. - 1
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- Med ”interkulturell blick” avses i denna antologi ett speciellt förhållningssätt. Perspektivet är gränsöverskridande och kosmopolitiskt. Det handlar om en ”inkluderande globalism”, en strävan att frigöra sig från etnocentriska synsätt för att i stället skapa en inkluderande, jämlik och demokratisk pedagogik. Det rör sig inte om någon kompenserande ”specialpedagogik för invandrare”. Snarare gäller det att med pedagogikens hjälp bidra till att göra det annorlunda normalt, till att skapa en ”diversifierad normalitet”.Boken är indelad i två delar: Interkulturalitet och samhälle samt Interkulturalitet och lärande. De flesta bidragen har skrivits av forskare och lärare vid Södertörns högskola och är baserade på författarnas forskning om interkulturell pedagogik. Bland bidragsgivarna finns också lärare som främst skriver utifrån sina praktiska yrkeserfarenheter av pedagogik och interkulturalitet.
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| 6. |
- Pirk, Norbert, et al.
(författare)
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Toward a statistical description of methane emissions from arctic wetlands
- 2017
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Ingår i: Ambio: a Journal of Human Environment. - : Springer Science and Business Media LLC. - 0044-7447. ; 46, s. 70-80
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Tidskriftsartikel (refereegranskat)abstract
- Methane (CH4) emissions from arctic tundra typically follow relations with soil temperature and water table depth, but these process-based descriptions can be difficult to apply to areas where no measurements exist. We formulated a description of the broader temporal flux pattern in the growing season based on two distinct CH4 source components from slow and fast-turnover carbon. We used automatic closed chamber flux measurements from NE Greenland (74°N), W Greenland (64°N), and Svalbard (78°N) to identify and discuss these components. The temporal separation was well-suited in NE Greenland, where the hypothesized slow-turnover carbon peaked at a time significantly related to the timing of snowmelt. The temporally wider component from fast-turnover carbon dominated the emissions in W Greenland and Svalbard. Altogether, we found no dependence of the total seasonal CH4 budget to the timing of snowmelt, and warmer sites and years tended to yield higher CH4 emissions.
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| 7. |
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| 8. |
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| 9. |
- Haraldsson, Joakim, 1990-, et al.
(författare)
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Barriers to and Drivers for Improved Energy Efficiency in the Swedish Aluminium Industry and Aluminium Casting Foundries
- 2019
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Ingår i: Sustainability. - Basel, Switzerland : MDPI AG. - 2071-1050. ; 11:7
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Tidskriftsartikel (refereegranskat)abstract
- Industrial energy efficiency is important for reducing CO2 emissions and could be a competitive advantage for companies because it can reduce costs. However, cost-effective energy efficiency measures are not always implemented because there are barriers inhibiting their implementation. Drivers for energy efficiency could provide means for overcoming these barriers. The aim of this article was to study the importance of different barriers to and drivers for improved energy efficiency in the Swedish aluminium industry and foundries that cast aluminium. Additionally, the perceived usefulness of different information sources on energy efficiency measures was studied. The data were collected through a questionnaire covering 39 barriers and 48 drivers, divided into different categories. Both the aluminium and foundry industries considered technological and economic barriers as the most important categories. The most important category of drivers for the aluminium industry was organisational drivers, while the foundries rated economic drivers as the most important. Colleagues within the company, the company group and sector, and the trade organisation were considered the most useful information sources. Important factors for driving work with improved energy efficiency included access to knowledge within the company, having a culture within the company promoting energy efficiency, and networking within the sector. The policy implications identified included energy labelling of production equipment, the law on energy audit in large companies and subsidy for energy audits in small- and medium-sized companies, voluntary agreements that included long-term energy strategies, increased taxes to improve the cost-effectiveness of energy efficiency measures, and EUs Emission Trading System.
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| 10. |
- Schubert-Hjalmarsson, E., et al.
(författare)
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Pain, Balance, Activity, and Participation in Children With Hypermobility Syndrome
- 2012
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Ingår i: Pediatric Physical Therapy. - 0898-5669. ; 24:4, s. 339-344
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To describe hypermobility, balance, pain, activity, and participation in children with hypermobility and compare these characteristics with those of a control group. Method: Twenty children aged 8 to 16 years with hypermobility syndrome (HMS) or Ehlers-Danlos syndrome and a control group of 24 children of the same age participated in the study. Hypermobility was assessed according to the Del Mar scale, balance was assessed with the Bruininks-Oseretsky test of motor proficiency, and participation in daily life activities was assessed with the frequency of participation questionnaire. Pain and physical activity were assessed in a diary. Results: In comparison with the control group, the children with hypermobility had significantly more hypermobile joints and more pain and scored lower in the balance test, and their activity was affected on a daily basis. Conclusion: Pain appears to affect activity and participation in children with HMS. Balance is decreased in children with HMS compared with healthy controls. (Pediatr Phys Ther 2012;24:339-344)
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