| 1. |
- Bengtsson, Johanna, 1974, et al.
(författare)
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Evaluations of effects due to low-frequency noise in a low demanding work situation
- 2004
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Ingår i: Journal of Sound and Vibration. - : Elsevier BV. - 0022-460X .- 1095-8568. ; 278:1-2, s. 83-99
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Tidskriftsartikel (refereegranskat)abstract
- Noise sources with a dominating content of low frequencies (20-200 Hz) are found in many occupational environments. This study aimed to evaluate effects of moderate levels of low-frequency noise on attention, tiredness and motivation in a low demanding work situation. Two ventilation noises at the same A-weighted sound pressure level of 45 dB were used: one of a low-frequency character and one of a flat frequency character (reference noise). Thirty-eight female subjects worked with six performance tasks for 4 h in the noises in a between-subject design. Most of the tasks were monotonous and routine in character. Subjective reports were collected using questionnaires and cortisol levels were measured in saliva. The major finding in this study was that low-frequency noise negatively influenced performance on two tasks sensitive to reduced attention and on a proof-reading task. Performances of tasks aimed at evaluating motivation were not significantly affected. The difference in work performance was not reflected by the subjective reports. No effect of noise was found on subjective stress or cortisol levels.
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| 2. |
- Bengtsson, Johanna, 1974, et al.
(författare)
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Sound characteristics in low frequency noise and their relevance for the perception of pleasantness
- 2004
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Ingår i: Acta Acoustica. ; 90:1, s. 171-180
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Tidskriftsartikel (refereegranskat)abstract
- Noise sources with a dominant content of low frequencies (20-200 Hz) are found in many occupational environments. Work efficiency has been found in two earlier studies to be impaired to a larger degree when working in a low frequency ventilation noise than when working in a flat frequency ventilation noise at the same A-weighted sound pressure level. Other previous studies indicate that different sound characteristics found in low frequency noise are important for the way in which low frequency noise affects humans, and better knowledge of these characteristics could lead to better methods for assessing low frequency noise in occupational environments. The aim of this study was to evaluate the influence of frequency balance between low and high frequencies, which affects the slope of the frequency spectra, and the modulation frequency on subjects´ perception of a pleasant low frequency noise. The results showed that the subjects preferred either a higher or a lower modulation frequency as compared to that of the original low frequency noise, both choices leading to less perceivable modulations. Furthermore, the subjects preferred a lower relative content of frequencies below 500 Hz, but only as long as the original low frequency noise contained modulations and the variations were made within a constant A-weighted sound pressure level. The results are discussed in relation to improved guidelines and to the previously suggested theory of slope of the frequency spectra and problems involved with the implementation of that theory.
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| 3. |
- Bergkvist, Bo, et al.
(författare)
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Pools and fluxes of carbon in three Norway spruce ecosystems along a climatic gradient in Sweden
- 2008
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 89:1, s. 7-25
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents an integrated analysis of organic carbon (C) pools in soils and vegetation, within-ecosystem fluxes and net ecosystem exchange (NEE) in three 40-year old Norway spruce stands along a north-south climatic gradient in Sweden, measured 2001-2004. A process-orientated ecosystem model (CoupModel), previously parameterised on a regional dataset, was used for the analysis. Pools of soil organic carbon (SOC) and tree growth rates were highest at the southernmost site (1.6 and 2.0-fold, respectively). Tree litter production (litterfall and root litter) was also highest in the south, with about half coming from fine roots (< 1 mm) at all sites. However, when the litter input from the forest floor vegetation was included, the difference in total litter input rate between the sites almost disappeared (190-233 g C m(-2) year(-1)). We propose that a higher N deposition and N availability in the south result in a slower turnover of soil organic matter than in the north. This effect seems to overshadow the effect of temperature. At the southern site, 19% of the total litter input to the O horizon was leached to the mineral soil as dissolved organic carbon, while at the two northern sites the corresponding figure was approx. 9%. The CoupModel accurately described general C cycling behaviour in these ecosystems, reproducing the differences between north and south. The simulated changes in SOC pools during the measurement period were small, ranging from -8 g C m(-2) year(-1) in the north to +9 g C m(-2) year(-1) in the south. In contrast, NEE and tree growth measurements at the northernmost site suggest that the soil lost about 90 g C m(-2) year(-1).
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| 4. |
- Björk, Robert G., 1974, et al.
(författare)
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Long-term warming effects on root morphology, root mass distribution, and microbial activity in two dry tundra plant communities in northern Sweden
- 2007
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 176:4, s. 862-873
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Tidskriftsartikel (refereegranskat)abstract
- center dot Effects of warming on root morphology, root mass distribution and microbial activity were studied in organic and mineral soil layers in two alpine ecosystems over > 10 yr, using open-top chambers, in Swedish Lapland. center dot Root mass was estimated using soil cores. Washed roots were scanned and sorted into four diameter classes, for which variables including root mass (g dry matter (g DM) m(-2)), root length density (RLD; cm cm(-3) soil), specific root length (SRL; m g DM-1), specific root area (SRA; m(2) kg DM-1), and number of root tips m(-2) were determined. Nitrification (NEA) and denitrification enzyme activity (DEA) in the top 10 cm of soil were measured. center dot Soil warming shifted the rooting zone towards the upper soil organic layer in both plant communities. In the dry heath, warming increased SRL and SRA of the finest roots in both soil layers, whereas the dry meadow was unaffected. Neither NEA nor DEA exhibited differences attributable to warming. center dot Tundra plants may respond to climate change by altering their root morphology and mass while microbial activity may be unaffected. This suggests that carbon may be incorporated in tundra soils partly as a result of increases in the mass of the finer roots if temperatures rise.
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| 5. |
- Byström, Pernilla, 1976, et al.
(författare)
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Appraised psychological workload, musculoskeletal symptoms, and the mediating effect of fatigue: A structural equation modeling approach.
- 2004
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Ingår i: Scandinavian Journal of Psychology. - : Wiley. ; 45:4, s. 331-341
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the present study was to test two structural models of the relationship between appraised psychologicla workload and musculoskeletal symptoms from the neck, shoulder, and upper and lower back with different aspects of perceived fatigue as mediating variables. In this cross-sectional study a questionnaire survey was conducted among employees at three Swedish assembly plants (n=305). The proposed models were tested for one general fatigue dimension - lack of energy - and four specific fatigue dimensions - physical discomfort, physical exertion, lack of motivation, and sleepiness - using structural equation modeling. The results indicate that the role of perceived fatigue in the relationship between appraised workload and musculoskeletal symptoms is different for different aspects of fatigue. The general fatigue dimension, lack of energy, does not mediate the relationship. As regards the specific fatigue dimensions, the relationship is partially mediated by physical discomfort and lack of motivation but not by physical exertion or sleepiness. Appraised psychological workload has a unique effect on musculoskeletal symptoms not mediated by fatigue.
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| 6. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 7. |
- Eliasson, Ingegärd, 1961, et al.
(författare)
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Climate and behaviour in a Nordic city
- 2007
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Ingår i: LANDSCAPE AND URBAN PLANNING. - : Elsevier BV. - 0169-2046 .- 1872-6062. ; 82:1-2, s. 72-84
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Tidskriftsartikel (refereegranskat)abstract
- Four urban public spaces, representing various designs and microclimates, were investigated in Gothenburg, Sweden, in order to estimate how weather and microclimate affect people in urban outdoor environments. The research strategy was both multidisciplinary and interdisciplinary and included scientists from three disciplines: architecture, climatology and psychology. The project is based on common case studies carried out during four seasons, including measurements of meteorological variables, interviews and observations of human activity at each place. Multiple regression analysis of meteorological and behavioural data showed that air temperature, wind speed and clearness index (cloud cover) have a significant influence on people's assessments of the weather, place perceptions and place-related attendance. The results support the arguments in favour of employing climate sensitive planning in future urban design and planning projects, as the physical component of a place can be designed to influence the site-specific microclimate and consequently people's place-related attendance, perceptions and emotions.
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| 8. |
- Eliasson, Ingegärd, 1961, et al.
(författare)
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Klimatet vänder turistströmmar
- 2009
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Ingår i: Miljöforskning. ; 1, s. 24-25:1, s. 24-25
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 9. |
- Gullberg, Annica, et al.
(författare)
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Prospective teachers’ initial conceptions about pupils’ understanding of science and mathematics
- 2008
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Ingår i: European Journal of Teacher Education. - : Informa UK Limited. - 0261-9768 .- 1469-5928. ; 31:3, s. 257-278
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Tidskriftsartikel (refereegranskat)abstract
- Earlier reports have shown that prospective teachers' conceptions about teaching science to a high degree are resistant and do not change substantially during the teacher-training programme. In our investigation we elucidate the prospective teachers' initial conceptions about pupils' understanding of science and mathematics. We applied 'The Lesson Preparation Method' and used a phenomenographic approach in order to reveal the range of conceptions that the prospective teachers hold. A third of the prospective teachers did not consider pupils' conceptions when planning lessons. The rest of the 32 participants expressed awareness; some of the prospective teachers even referred to subject-specific teaching experience. Also regarding the prospective teachers' conceptions about pupils' knowledge and beliefs, as well as about pupils' difficulties, there was a significant diversity. By raising these issues about pedagogical content knowledge the prospective teachers' conceptions can be extended and developed during the education.
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| 10. |
- Haglund, Björn, 1962, et al.
(författare)
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Afterschool Programs and Leisure-Time Centres: Arenas for Learning and Leisure
- 2009
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Ingår i: World Leisure Journal. - : Informa UK Limited. - 0441-9057 .- 1607-8055 .- 2333-4509. ; 51:2, s. 116-129
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Afterschool programs in the United States and leisure-time centres in Sweden could emphasize children’s leisure as well as be of importance to children’s learning. However, in both cases, the association to leisure is mostly ignored and the acceptance is not widely practiced. Instead, other discourses that partly are more related to the field of education serve as a guide for programming in afterschool programs and leisure-time centres. The authors present the argument that afterschool programs and leisure-time centres could be more associated with leisure activities and presented in a new way with the guidance from the field of leisure that also could be beneficial for educational research. Existing definitions of leisure, and their possible consequences for the activities, are discussed in terms of the framework of afterschool programs and leisure-time centres. The authors argue that knowledge grounded in understanding the importance of leisure and its potential to develop and satisfy people could be a means to develop both the activities and the current work of the staff in afterschool programs and leisure-time centres.
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