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Sökning: WFRF:(Nilsson Staffan) > Nilsson Mats

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1.
  • Alvarsson, Jesper J. (författare)
  • Perspectives on wanted and unwanted sounds in outdoor environments : Studies of masking, stress recovery, and speech intelligibility
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • An acoustic environment contains sounds from various sound sources, some generally perceived as wanted, others as unwanted. This thesis examines the effects of wanted and unwanted sounds in acoustic environments, with regard to masking, stress recovery, and speech intelligibility.In urban settings, masking of unwanted sounds by sounds from water structures has been suggested as a way to improve the acoustic environment. However, Study I showed that the unwanted (road traffic) sound was better at masking the wanted (water) sound than vice versa, thus indicating that masking of unwanted sounds with sounds from water structures may prove difficult. Also, predictions by a partial loudness model of the auditory periphery overestimated the effect of masking, indicating that centrally located informational masking processes contribute to the effect. Some environments have also been shown to impair stress recovery; however studies using only auditory stimuli is lacking. Study II showed that a wanted (nature) sound improve stress recovery compared to unwanted (road traffic, ambient) sounds. This suggests that the acoustic environment influences stress recovery and that wanted sounds may facilitate stress recovery compared to unwanted sounds. An additional effect of unwanted sounds is impeded speech communication, commonly measured with speech intelligibility models. Study III showed that speech intelligibility starts to be negatively affected when the unwanted (aircraft sound) masker have equal or higher sound pressure level as the speech sound. Three models of speech intelligibility (speech intelligibility index, partial loudness and signal–to–noise ratio) predicted this effect well, with a slight disadvantage for the signal–to–noise ratio model. Together, Study I and III suggests that the partial loudness model is useful for determining effects of wanted and unwanted sounds in outdoor acoustic environments where variations in sound pressure level are large. But, in environments with large variations in other sound characteristics, models containing predictions of central processes would likely produce better results.The thesis concludes that wanted and unwanted characteristics of sounds in acoustic environments affect masking, stress recovery, and speech intelligibility, and that auditory perception models can predict these effects.
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2.
  • Bergman, Inger, et al. (författare)
  • The influence of sulphate deposition on the seasonal variation of peat pore water methyl Hg in a boreal mire
  • 2012
  • Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:9, s. e45547-
  • Tidskriftsartikel (refereegranskat)abstract
    • In this paper we investigate the hypothesis that long-term sulphate (SO42-) deposition has made peatlands a larger source of methyl mercury (MeHg) to remote boreal lakes. This was done on experimental plots at a boreal, low sedge mire where the effect of long-term addition of SO42- on peat pore water MeHg concentrations was observed weekly throughout the snow-free portion of 1999. The additions of SO42- started in 1995. The seasonal mean of the pore water MeHg concentrations on the plots with 17 kg ha(-1) yr(-1) of sulphur (S) addition (1.3 +/- 0.08 ng L-1, SE; n=44) was significantly (p<0.0001) higher than the mean MeHg concentration on the plots with 3 kg ha(-1) yr(-1) of ambient S deposition (0.6 +/- 0.02 ng L-1, SE; n=44). The temporal variation in pore water MeHg concentrations during the snow free season was larger in the S-addition plots, with an amplitude of >2 ng L-1 compared to +/-0.5 ng L-1 in the ambient S deposition plots. The concentrations of pore water MeHg in the S-addition plots were positively correlated (r(2)=0.21; p=0.001) to the groundwater level, with the lowest concentrations of MeHg during the period with the lowest groundwater levels. The pore water MeHg concentrations were not correlated to total Hg, DOC concentration or pH. The results from this study indicate that the persistently higher pore water concentrations of MeHg in the S-addition plots are caused by the long-term additions of SO42- to the mire surface. Since these waters are an important source of runoff, the results support the hypothesis that SO42- deposition has increased the contribution of peatlands to MeHg in downstream aquatic systems. This would mean that the increased deposition of SO42- in acid rain has contributed to the modern increase in the MeHg burdens of remote lakes hydrologically connected to peatlands.
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3.
  • Bishop, Kevin, et al. (författare)
  • The Effects of Forestry on Hg Bioaccumulation in Nemoral/Boreal Waters and Recommendations for Good Silvicultural Practice
  • 2009
  • Ingår i: Ambio. - : Royal Swedish Academy of Sciences. - 0044-7447 .- 1654-7209. ; 38:7, s. 373-380
  • Tidskriftsartikel (refereegranskat)abstract
    • Mercury (Hg) levels are alarmingly high in fish from lakes across Fennoscandia and northern North America. The few published studies on the ways in which silviculture practices influence this problem indicate that forest operations increase Hg in downstream aquatic ecosystems. From these studies, we estimate that between one-tenth and one-quarter of the Hg in the fish of high-latitude, managed forest landscapes can be attributed to harvesting. Forestry, however, did not create the elevated Hg levels in the soils, and waterborne Hg/MeHg concentrations downstream from harvested areas are similar to those from wetlands. Given the current understanding of the way in which silviculture impacts Hg cycling, most of the recommendations for good forest practice in Sweden appear to be appropriate for high-latitude regions, e.g., leaving riparian buffer zones, as well as reducing disturbance at stream crossings and in moist areas. The recommendation to restore wetlands and reduce drainage, however, will likely increase Hg/MeHg loadings to aquatic ecosystems
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4.
  • Fritsche, Johannes, et al. (författare)
  • Evasion of Elemental Mercury from a Boreal Peat land Suppressed by Long-Term Sulfate Addition
  • 2014
  • Ingår i: ENVIRONMENTAL SCIENCE & TECHNOLOGY LETTERS. - : American Chemical Society (ACS). - 2328-8930. ; 1:10, s. 421-425
  • Tidskriftsartikel (refereegranskat)abstract
    • We investigated the evasion of TGM (total gaseous mercury) from experimental plots on a boreal peatland that had been exposed for 15 years to different combinations of atmospheric sulfur (5) and nitrogen (N) deposition as well as greenhouse treatments simulating climate change. Shaded dynamic flux chamber measurements during the summer in 2009 showed emission of TGM to the atmosphere from most of the treated plots (0.7 +/- 0.94 ng m(-2) h(-1)). However, TGM exchange rates were significantly lower, occasionally indicating Hg uptake, on plots subjected to S addition at rates of 20 kg ha(-1) year(-1). Enhanced nitrogen deposition and greenhouse treatment had no significant effect on TGM fluxes. We hypothesize that the lower Hg evasion from the sulfur-treated plots is related to either earlier Hg evasion or Hg binding to S in organic matter, making, Hg less susceptible to volatilization and more prone to transport in runoff.
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5.
  • Jahncke, Helena (författare)
  • Cognitive performance and restoration in open-plan office noise
  • 2012
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • This dissertation presents four experimental studies (in four papers) with the overall aim to investigate the effects of office noise on cognitive performance and restoration. In the first two papers the focus was on the effects of different sound levels (i.e., the mean level from all sound sources at an office, such as speech, phones, people walking) on performance, fatigue and stress. In the last two papers the focus was on the effects of background speech, as this has previously been shown to be the most disturbing noise source in open-plan offices. Paper I demonstrated decreased word memory performance, increased fatigue and motivational deficits when the background sound level increased by 12 dB, from 39 to 51 dB LAeq. Paper II showed that the sound level effects were more pronounced for individuals with a hearing impairment. Unexpectedly, no effects were found of acute noise exposure on the participant´s stress hormone levels (Paper I and Paper II).Regarding effects of irrelevant speech, Paper III showed that cognitive performance decreased as a function of background speech intelligibility, the higher the intelligibility depicted by the Speech Transmission Index (STI), the worse the performance. The results indicated that the STI-value must be less than 0.50, to avoid a negative influence on performance. Further, both Paper III and IV showed that performance is more impaired by background speech if the focal task requires episodic memory and rehearsal—such as word memory and information search. Interestingly, some tasks were insensitive for speech.The restorative effects of a break were addressed in Paper I and II (i.e., directly after the work sessions in noise). The break period differed in content between the participants. Paper I showed that a break with a nature movie with corresponding sound increased energy ratings compared to just listening to river sounds or office noise. Continued exposure to office noise gave the lowest ratings of motivation after the break. Paper II showed improved arithmetic performance and motivation after the break with a nature movie and decreased performance and motivation after continued noise exposure. For the hearing impaired participants, however, continued noise during the break increased motivation and performance, while the movie did not.Taken together, the current thesis demonstrates that open-plan office noise can have a negative impact on fatigue, motivation and performance. How much performance is impaired varies with the cognitive processes required by the tasks performed and hearing status. Moreover, continued noise exposure during a short break can further decrease motivation and subsequent performance.
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6.
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7.
  • Jonsson, Sofi, et al. (författare)
  • Terrestrial discharges mediate trophic shifts and enhance methylmercury accumulation in estuarine biota
  • 2017
  • Ingår i: Science Advances. - : American association for the advancement of science. - 2375-2548. ; 3:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The input of mercury (Hg) to ecosystems is estimated to have increased two- to fivefold during the industrial era, and Hg accumulates in aquatic biota as neurotoxic methylmercury (MeHg). Escalating anthropogenic land use and climate change are expected to alter the input rates of terrestrial natural organic matter (NOM) and nutrients to aquatic ecosystems. For example, climate change has been projected to induce 10 to 50% runoff increases for large coastal regions globally. A major knowledge gap is the potential effects on MeHg exposure to biota following these ecosystem changes. We monitored the fate of five enriched Hg isotope tracers added to mesocosm scale estuarine model ecosystems subjected to varying loading rates of nutrients and terrestrial NOM. We demonstrate that increased terrestrial NOM input to the pelagic zone can enhance the MeHg bioaccumulation factor in zooplankton by a factor of 2 to 7 by inducing a shift in the pelagic food web from autotrophic to heterotrophic. The terrestrial NOM input also enhanced the retention of MeHg in the water column by up to a factor of 2, resulting in further increased MeHg exposure to pelagic biota. Using mercury mass balance calculations, we predict that MeHg concentration in zooplankton can increase by a factor of 3 to 6 in coastal areas following scenarios with 15 to 30% increased terrestrial runoff. The results demonstrate the importance of incorporating the impact of climate-induced changes in food web structure on MeHg bioaccumulation in future biogeochemical cycling models and risk assessments of Hg.
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8.
  • Lennestål, Roland, et al. (författare)
  • Serum levels of olanzapine in a non-fatal overdose
  • 2007
  • Ingår i: Journal of Analytical Toxicology. - 0146-4760 .- 1945-2403. ; 31:2, s. 119-121
  • Tidskriftsartikel (refereegranskat)abstract
    • Olanzapine is a widely used second generation antipsychotic drug. Case reports of intoxications have been published, but reports in the literature of non-fatal intoxications of olanzapine containing repeated measurements of serum levels are scarce. Therefore, this case of non-fatal olanzapine intoxication is presented, in which 19 blood samples were drawn during 2 weeks. The highest (initial) measured value was estimated at 800 μg/L. This patient ingested 550 mg of olanzapine resulting in clinical signs of intoxication, including seizures. Because the patient was found the day after the intoxication, the initial concentration had probably been higher. The pharmacokinetics of olanzapine has been described as linear and dose-proportional throughout the therapeutic dosing range. Large overdoses, however, have been described to show non-linear pharmacokinetics. In this study's series of serum concentrations, a two-phase elimination was seen, with an initial elimination half-life of about 24 h during the first 3 days, followed by a second phase with a half-life of about 2.5 days. The patient in this case recovered completely. Because the elimination time after intoxication can be considerably longer than expected, it is recommended that the patient's serum concentrations after intoxication be monitored.
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9.
  • Ljung, Robert (författare)
  • Room acoustics and cognitive load when listening to speech
  • 2010
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • The present thesis investigated the effects of background noise or a long reverberation time in learning situations. All studies used spoken texts that were presented above the speech intelligibility threshold, but were degraded enough to make listening more effortful. The basic hypothesis for the whole project was that listening to speech in a bad acoustic environment should increase the cognitive load for the listener, which should impair memory of the text. In Paper I the auditory stimuli were lists of words and sentences that were degraded by a background noise. Paper II was a replication of the experiment from paper I, but the independent variable was changed from the level of the background noise to reverberation time. Paper III included two experiments where the stimulus material was 10 minutes lectures.Paper IV included two studies. The first experiment investigated whether serial recall performance is affected when words are presented in long reverberation time (Exp 1a). In experiment 1b word lists were presented in long or short reverberation time or with a background noise. The stimuli were recorded in one classroom with extremely good and one with very bad acoustic design. In experiment 2 word lists with many or few phonological neighbours were presented with long or short reverberation time. In all studies some measure of working memory capacity was included. Taken together, the overall results could be summarized in two sentences: Hearing what is said is a necessary but not a sufficient criterion for people to remember what is said, which means that spoken information should be heard without special effort, otherwise proper learning is jeopardized. No consistent relation was found between working memory capacity and the learning effect in the unfavorable listening conditions.
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10.
  • Osterwalder, S., et al. (författare)
  • Comparative study of elemental mercury flux measurement techniques over a Fennoscandian boreal peatland
  • 2018
  • Ingår i: Atmospheric Environment. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1352-2310 .- 1873-2844. ; 172, s. 16-25
  • Tidskriftsartikel (refereegranskat)abstract
    • Quantitative estimates of the land-atmosphere exchange of gaseous elemental mercury (GEM) are biased by the measurement technique employed, because no standard method or scale in space and time are agreed upon. Here we present concurrent GEM exchange measurements over a boreal peatland using a novel relaxed eddy accumulation (REA) system, a rectangular Teflon (R) dynamic flux chamber (DFC) and a DFC designed according to aerodynamic considerations (Aero-DFC). During four consecutive days the DFCs were placed alternately on two measurement plots in every cardinal direction around the REA sampling mast. Spatial heterogeneity in peat surface characteristics (0-34 cm) was identified by measuring total mercury in eight peat cores (57 +/- 8 ng g(-1), average SE), vascular plant coverage (32-52%), water table level (4.5-14.1 cm) and dissolved gaseous elemental mercury concentrations (28-51 pg L-1) in the peat water. The GEM fluxes measured by the DFCs showed a distinct diel pattern, but no spatial difference in the average fluxes was detected (ANOVA, alpha = 0.05). Even though the correlation between the Teflon DFC and Aero-DFC was significant (r = 0.76, p < 0.05) the cumulative flux of the Aero-DFC was a factor of three larger. The average flux of the Aero-DFC (1.9 ng m(-2) h(-1)) and REA (2 ng m(-2) h(-1)) were in good agreement. The results indicate that the novel REA design is in agreement for cumulative flux estimates with the Aero-DFC, which incorporates the effect of atmospheric turbulence. The comparison was performed over a fetch with spatially rather homogenous GEM flux dynamics under fairly consistent weather conditions, minimizing the effect of weather influence on the data from the three measurement systems. However, in complex biomes with heterogeneous surface characteristics where there can be large spatial variability in GEM gas exchange, the small footprint of chambers ( < 0.2 m(2)) makes for large coefficients of variation. Thus many chamber measurement replications are needed to establish a credible biome GEM flux estimate, even for a single point in time. Dynamic flux chambers will, however, be able to resolve systematic differences between small scale features, such as experimentally manipulated plots or small scale spatial heterogeneity.
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