| 1. |
- Berg, Björn, et al.
(författare)
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Factors influencing limit values for pine needle litter decomposition : A synthesis for boreal and temperate pine forest systems
- 2010
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 100:1, s. 57-73
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Tidskriftsartikel (refereegranskat)abstract
- We synthesized available data for decomposition of pine (Pinus) needle litter in pine forests to determine the litter chemical characteristics and climate factors that explained variation in the limit value, i. e. the level of accumulated mass loss at which the decomposition process either continues at a very low rate or possibly stops. Our data base included 56 separate studies on decomposition of pine needle litter, spanning Scots pine, lodgepole pine, Aleppo pine, stone pine and white pine, mainly incubated at the site of collection. Studies had 5 to 19 samplings, on average 10, and the decomposition was followed to a mass loss ranging from 47 to 83%, on average 67%. The periods from 3.0 to 5.4 years, on average 3.9 years, were of sufficient duration to allow estimates of limit values of decomposition. We used a linear mixed model with regression effects to relate limit values to potential explanatory variables, namely the sites' long-term mean annual temperature (MAT) and mean annual precipitation (MAP) and to substrate-chemistry factors. Regarding the latter, we explored two models; one that included initial concentrations of water solubles, lignin, N, P, K, Ca, Mg, and Mn and one that included only lignin, N, Ca, and Mn to focus on those nutrients known to influence lignin degradation. Using backward elimination significant explanatory variables were determined. For litter decomposed in its site of origin we found the limit value to depend mainly on the initial concentration of Mn, with higher Mn concentrations resulting in higher accumulated mass loss. Thus, litter with higher Mn reached a higher limit value and left a smaller stable fraction. This is likely due to the fact that Mn is an essential component of ligninolytic enzymes important for degrading litter in the later stages of decomposition. Manganese has received little attention in decomposition studies to date. Given its significance in this synthesis, the role of Mn in influencing variation in the late stages of decomposition among ecosystems and among litters of other genera besides Pinus deserves further attention.
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| 2. |
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| 3. |
- Asami-Johansson, Yukiko, et al.
(författare)
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Comparing mathematics education lessons for primary school teachers : case studies from Japan, Finland and Sweden
- 2020
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Ingår i: International Journal of Mathematical Education in Science and Technology. - : Taylor & Francis. - 0020-739X .- 1464-5211. ; 51:5, s. 688-712
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this paper is to investigate and compare lessons given in primary school teacher education in Japan, Finland and Sweden. We analyse one lesson from each country and compare them using a common framework. Chevallard’s anthropological theory of the didactic (ATD) is used to frame this analysis and in particular to model teacher educators' didactic organization of the lessons. The focus is on how the didactic organizations of the teacher educators relate to the mathematical and didactic organizations of primary school. Based on official documents and viewpoints of the teacher educators, we also discuss how the contents and descriptions of the national curricula, and the different traditions of the teaching practices in each country, influence the didactic organizations found in the lessons.
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| 4. |
- Béland, M. -C, et al.
(författare)
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Optical measurement and perception of gloss quality of printed matte-coated paper
- 2000
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Ingår i: Journal of Pulp and Paper Science (JPPS). - : Canadian Pulp & Paper Assoc, Montreal, Canada. - 0826-6220. ; 26:3, s. 120-123
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Tidskriftsartikel (refereegranskat)abstract
- A set of 32 commercially produced and printed matte-coated papers were rated for gloss quality by a panel of 13 expert judges and light-scattering distributions, gloss and gloss variation of the prints were measured. Fitting the light-scattering distributions to Von Mises distributions, we obtain a factor, kappa, related to the width of the distribution and sensitive to small changes in surface roughness. This factor relates very well with the subjective rating. Gloss variation in the 3.3 to 6.6 mm wavelength band also correlates well with the gloss quality rating. The topography of the samples was also measured using confocal microscopy and a good correlation was found between the median facet angle and the kappa values.
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| 5. |
- Bombardi, C., et al.
(författare)
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Immunohistochemical localization of alpha(1a)-adrenoreceptors in muscle spindles of rabbit masseter muscle
- 2006
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Ingår i: Tissue & Cell. - : Elsevier BV. - 0040-8166 .- 1532-3072. ; 38:2, s. 121-125
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Tidskriftsartikel (refereegranskat)abstract
- The expression of alpha(1a)-adrenoreceptors (alpha(1a)-ARs) within the muscle spindles of rabbit masseter muscle was investigated. The alpha(1a)-ARs were detected by immunohistochemical fluorescent method and examined along the entire length of 109 cross serially sectioned spindles. The sympathetic fibers were visualized by the immunofluorescent labeling of the noradrenaline synthesizing enzymes tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (DBH). In order to recognize the intrafusal muscle fiber types, antibodies for different myosin heavy chain isoforms (MyHCI) were used. TH and DBH immunolabeled nerve fibers have been observed within the capsule lamellar layers, in the periaxial fluid space and close to intrafusal muscle fibers. The alpha(1a)-ARs were detected on the smooth muscle cells of the blood vessels coursing in the muscle and in the capsule lamellar layers or within the periaxial fluid space of the spindles. Moreover, at the polar regions of a high percentage (88.1%) of muscle spindles a strong alpha(1a)-ARs immunoreactivity was present on the intrafusal muscle fibers. In double immunostained sections for alpha(1a)-ARs and MyHCI it was evidenced that both bag, and nuclear chain fibers express alpha(1a)-ARs. The receptors that we have detected by immunofluorescence may support a direct control by adrenergic fibers on muscle spindle.
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