| 3981. |
- Sundström (Raman), Manya, 1971-
(författare)
-
Key ideas : What are they and how can they help us understand people view proof?
- 2003
-
Ingår i: Educational Studies in Mathematics. - 0013-1954 .- 1573-0816. ; 52:3, s. 319-325
-
Tidskriftsartikel (refereegranskat)abstract
- This paper examines the views of proof held by university level mathematics students and teachers. A framework is developed for characterizing people's views of proof, based on a distinction between public and private aspects of proof and the key ideas which link these two domains.
|
|
| 3982. |
- Sunesson, Anna-Lena, et al.
(författare)
-
Passive sampling in combination with thermal desorption and gas chromatography as a tool for self-assessment of chemical exposure
- 2002
-
Ingår i: Journal of Environmental Monitoring. - : Royal Society of Chemistry. - 1464-0325 .- 1464-0333. ; 4:5, s. 706-710
-
Tidskriftsartikel (refereegranskat)abstract
- Diffusive samplers for monitoring of air quality are user-friendly devices that can normally be operated by the user himself. Hence these samplers are suitable for self-assessment. Practical and work organisational aspects of self-assessment of chemical exposure were studied in different occupational settings. It was found that the diffusive sampler used in these studies, the Perkin-Elmer tube in combination with thermal desorption, worked well for the purpose and could be correctly handled by the individuals using it. The results from self-assessments agreed well with expert measurements carried out by an occupational hygienist. However, in order to obtain a sustainable system of self-assessment strong organizational support is needed.
|
|
| 3983. |
- Sunnegårdh-Grönberg, Karin, 1969-, et al.
(författare)
-
Flexural strength and modulus of a novel ceramic restorative cement intended for posterior restorations as determined by a three-point bending test
- 2003
-
Ingår i: Acta Odontologica Scandinavica. - : Taylor & Francis. - 0001-6357 .- 1502-3850. ; 61:2, s. 87-92
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to compare a new restorative cement intended for posterior restorations, Doxadent, with other types of tooth-colored materials as regards flexural strength and flexural modulus. The new restorative material consists mainly of calcium aluminate. Four hybrid resin composites, one polyacid-modified resin composite, one resin-modified glass ionomer cement, one conventional glass ionomer cement, one zinc phosphate cement, and an experimental version as well as the marketed version of Doxadent were investigated. Flexural strength and flexural modulus were tested according to ISO standard 4049 and determined after 1 d, 1 week, and 2 weeks. Together with the zinc phosphate cement, Doxadent had the lowest flexural strengths (13-22 MPa). The strongest materials were the resin composites and the polyacid-modified resin composite (83-136 MPa). The highest flexural modulus was found for Doxadent (17-19 GPa). The flexural strength of Doxadent decreased significantly from 1 week to 2 weeks, while flexural modulus remained unchanged. The other materials reacted in different ways to prolonged water storage. It can be concluded that the restorative cement Doxadent had significantly lower flexural strength and significantly higher flexural modulus than today's materials used for direct posterior restorations.
|
|
| 3984. |
- Sunnegårdh-Grönberg, Karin, 1969-, et al.
(författare)
-
Hardness and in vitro wear of a novel ceramic restorative cement
- 2002
-
Ingår i: European Journal of Oral Sciences. - : John Wiley & Sons, Inc. - 0909-8836 .- 1600-0722. ; 110:2, s. 175-178
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of the present work was to compare a new ceramic restorative cement for posterior restorations, DoxaDent, with other types of tooth-colored materials for direct use as regards hardness and in vitro wear. Four hybrid resin composites, one polyacid-modified resin composite, one resin-modified glass ionomer cement, one conventional glass ionomer cement, one zinc phosphate cement, an experimental version as well as the marketed version of the ceramic restorative cement, were investigated. Hardness of the materials was tested with the Wallace indentation tester and wear was tested with the ACTA wear machine. All tests were carried out on 2-wk-old specimens. DoxaDent was as hard as the zinc phosphate cement and the hardest resin composite. The ceramic restorative cement wore significantly more than the resin composites, the same as the zinc phosphate cement, and less than the glass ionomer cements. No correlation between hardness and wear was found. It can be concluded that the ceramic restorative cement is a rather hard material but with a relatively low wear resistance.
|
|
| 3985. |
- Sunnegårdh-Grönberg, Karin, 1969-, et al.
(författare)
-
Interfacial adaptation of a calcium aluminate cement used in class II cavities, in vivo
- 2004
-
Ingår i: Clinical Oral Investigations. - : Springer-Verlag. - 1432-6981 .- 1436-3771. ; 8:2, s. 75-80
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this in vivo study was to evaluate the interfacial marginal adaptation of a calcium aluminate cement, Doxadent (DD), and to compare it intra-individually with a resin composite, Tetric Ceram/Syntac Single-Component (TC/SS), in Class II cavities. Sixteen Class II box-shaped, enamel-bordered cavities were prepared in eight premolars scheduled to be extracted after 1 month's service for orthodontic reasons. The interfacial marginal adaptation (internal surfaces) of the restorations was evaluated by a quantitative scanning electron microscope analysis using a replica method. DD showed a statistically significant, lower degree of gap-free adaptation to enamel compared with TC/SS: 84% vs. 93%. To dentin, DD showed a significantly better adaptation than TC/SS: 72% vs. 49%. A high frequency of enamel fractures perpendicular to the margins was observed for the DD restorations, which may be explained by an expansion of the calcium-aluminate cement. It can be concluded that DD showed a better adaptation to dentin while TC/SS showed a better adaptation to enamel. The dimensional changes of DD have to be investigated before clinical use can be recommended.
|
|
| 3986. |
- Sunnegårdh-Grönberg, Karin, 1969-, et al.
(författare)
-
Surface roughness of a novel "ceramic restorative cement" after treatment with different polishing techniques in vitro
- 2003
-
Ingår i: Clinical Oral Investigations. - : Springer-Verlag. - 1432-6981 .- 1436-3771. ; 7:1, s. 27-31
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to determine the surface roughness of a novel calcium aluminate cement (CAC) intended for posterior restorations after treatment with different polishing devices in vitro. Forty-eight CAC specimens were polished with diamond burs at 15,550 rpm or 27,000 rpm, Sof-Lex discs, Jiffy points, Shofu silicone points, and Aaba universal polisher. Amalgam specimens were polished with Shofu silicone points and used as reference. Roughness was measured using a profilometer. The smoothest CAC surface was observed after use of the fine Sof-Lex disc (roughness average [Ra] 0.26 mm). Diamond burs at higher speed, points, and polisher gave rather similar results (Ra 0.58–0.72 mm). An increase in surface roughness could be seen from using diamond burs at lower speed (Ra 2.3 mm). Extra fine Shofu points and Sof-Lex discs as a final step reincreased surface roughness. Polished amalgam showed the smoothest surface in the study (Ra 0.17). It can be concluded that the smoothest CAC surfaces were obtained with the fine Sof-Lex discs. Different polishing points and diamond burs at higher speed, which are suitable polishing devices for posterior restorations, also gave relatively smooth surfaces.
|
|
| 3987. |
- Suominen, O, et al.
(författare)
-
Impacts of semi-domesticated reindeer on structure of tundra and forest communities in Fennoscandia : a review
- 2000
-
Ingår i: Annales Zoologici Fennici. - 0003-455X .- 1797-2450. ; 37:4, s. 233-249
-
Tidskriftsartikel (refereegranskat)abstract
- Grazing and trampling by semi-domesticated reindeer are important factors controlling vegetation in northern Fennoscandia. In this article we review Nordic studies on the effects of reindeer on vegetation and animal communities. The studies have shown clear effects on vegetation, especially on Cladina lichen dominated sites. Cladina is the main forage of reindeer during winter and dominates climax vegetation in dry site types in the absence of reindeer. Reindeer can even affect galling and ground-dwelling invertebrates. Due to the special relationship between reindeer and Cladina majority of the research has concentrated on winter grazing on Cladina, but there are some studies of summer grazing which have also shown substantial changes in vegetation. Reindeer grazing increases richness and diversity of vegetation and invertebrate assemblages in most cases, but this influence depends on site type and grazing intensity. The enriching effect seems to be strongest at moderate grazing intensity.
|
|
| 3988. |
|
|
| 3989. |
- Svallfors, Stefan, 1961-
(författare)
-
Class, attitudes and the Welfare State : Sweden in comparative perspective
- 2004
-
Ingår i: Social Policy & Administration. - : Wiley. - 0144-5596 .- 1467-9515. ; 38:2, s. 119-138
-
Tidskriftsartikel (refereegranskat)abstract
- One of the most important arenas for contemporary class politics is the welfare state. In this article, attitudes towards welfare policies among different classes in Sweden are compared with other Western countries and over time. In the first part of the article, attitudes towards state intervention among different classes are compared across four Western countries: Sweden, Germany, Britain and the USA. The data come from the 1996 survey on "The Role of Government" conducted within the International Social Survey Programme. In the second part of the article, more detailed national data sets are used in order to track developments within Sweden from the early 1980s until 2002. Attitudes towards welfare spending, financing of welfare policies and service delivery are used to track developments of class differences in attitudes over time. It is concluded (a) that class differences are particularly large in Sweden, and (b) that changes over time indicate stability in overall class differences, combined with changes in attitudes among non-manual employees. The implications of the results for recent arguments about the restructuring of class relations and the impact of welfare policies on stratification are discussed.
|
|
| 3990. |
|
|
