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- Waara, Sylvia, 1958-
(författare)
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Production and characterization of intraspecific somatic hybrids of potato (Solanum tuberosum L.)
- 1991
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A culture protocol has been developed for mesophyll protoplasts isolated from various d¡haploid clones of potato. A large number of call¡ was obtained after serial dilution of the cultures w¡th a suitable amount and type of medium at different stages of cell colony development.A polyelhylene glycol fusion procedure was developed that yielded up to 12 % heterokaryons. Using this fusion protocol hybrid cells have been manually lsolated, cultured and regenerated into plants. Fus¡on products were identified 2-3 days after fuslon by the dual fluorescence emission from the chloroplasts in mesophyll protoplasts (red) and the fluorescein diacetate stain in l¡ght and norflurazon bleached protoplasts (yellow-green). This fusion and select¡on strategy leads to the recovery of almost 100 % hybr¡d plants as established by isozyme analysls.Cytolog¡cal analysis of protoplast-derived plants and somatic hybrid plants revealed genetic changes as a consequence of protoplast culture and protoplast fus¡on. Twenty-three tetraplo¡d somatic hybrid plants were obta¡ned from 6 different calli and 9 of these were euploid.Morphological assessments of somatic hybr¡d plants of different ploidy levels demonstrated that tetraploid as well as several hexaploid somatic hybrids showed an increased vigour as compared to the parental plants. Most tetraploid somat¡c hybrids had a similar appearance although not all euploid plants were identical. Loss of vigour was evident in all mixoploid and octoplo¡d plants. These were stunted, weak and had an abnormal leaf morphology.The plastid type in hybrid plants was determined by RFLP analysis. All analysed hybrids had a cpDNA restrict¡on fragment pattern ¡dent¡cal to one of the parents wh¡ch contained either S. tuberosum or S. stoloniferum cpDNA. A slight preference for S. tuberosum plastids was observed in hybild plants. No influence on tho assortment of chloroplast by the norflurazon bleaching could be detected.
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| 3. |
- Ormarsson, Sigurdur, 1963-
(författare)
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Numerical Analysis of Moisture-Related Distortion in Sawn Timber
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A 3D theory for the numerical simulation of deformations and stresses in wood during moisture variation is described. The constitutive model employed assumes the total strain rate to be the sum of the elastic strain rate, the moisture-induced strain rate, the mechano-sorption strain rate and the creep strain rate. The 3D theory used for analyzing the shape stability of sawn timber was implemented in a finite element program. To illustrate the types of results that can be obtained, the behaviour of boards during drying was simulated. .....
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| 4. |
- Haglund, Åsa
(författare)
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Sensory quality of tomato, carrot and wheat : Influences of growing systems
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The sensory variation in products, conventionally and ecologically grown has been described and the effect of sensory training on the reliability of the assessors has been evaluated.Ecologically grown tomatoes scored higher for sweetness while conventionally grown tomatoes scored higher for firmness. For total taste intensity, acidity and bitterness, there was an interaction between growing system and variety. In a controlled experiment, nutritiously poor growing substrate produced a low yield of sweet, firm and less juicy tomatoes. Nutritiously rich growing substrate produced a high yield of less sweet, less firm but juicier tomatoes. Late harvest resulted in an increase of total taste intensity and a decrease of the bitter taste of the tomatoes.Conventionally grown carrots scored high for carrot-taste, while ecologically grown scored high for bitter taste. In one out of two years conventionally grown carrots were sweeter and crunchier while ecologically grown carrots were harder. Conventionally produced wheat samples had significantly higher protein levels compared with ecologically produced wheat samples. The volume of the wholemeal bread was related to the protein content and there was a close relationship between volume and elasticity of the bread.It was observed that information on labelling as being ecologically grown caused an increase in product rating. For sweet tomatoes with high tomato taste intensity, the information on them being grown ecologically was less important for consumer preference. During training the variation in reproducibility within assessors decreased and the assessors' ability to detect differences between samples increased.
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| 5. |
- Johannesson, Mikael, 1959-
(författare)
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Risk Management Under Uncertainty : Strategies for protecting health and the environment
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis deals with problems related to the management of environmental and health risks and problems. The general hypothesis of this work was that there are possibilities of making considerable improvements in the decision analysis and management of complicated environmental and health risks and problems. Specific attention has been paid to decision-situations involving great uncertainty and to how different decision-makers handle these extraordinarily difficult risk management situations. The studies focus on the risk management of the threat of anthropogenic climate change and chemical hazards, and on the legal and administrative risk management system in Sweden.A general conclusion is that there is room for considerable improvement in the risk management of environmental and health risks in the investigated areas. Increased use of decision theory and development of priority-setting strategies are two important tools for such improvement. Further, increased attention to the following issues will also contribute to improved risk managment: 1) the demarcation of the analysis, 2) surprises and worst cases, 3) separation and identification of scientific and non-scientific issues, 4) the distribution of the burden of proof, and 5) the scientists' and regulators' different roles.It can be concluded from the experience reported in the four papers in this thesis that it is fruitful to combine different perspectives when studying risks and the management of risk in a comprehensive approach. Three perspectives have been identified and used: (I) the actor perspective, (II) the cause perspective and (III) the risk/problem perspective. The three perspectives complement each other by giving different kinds of information eventhough they are closely linked together. A general model applicable to all kinds of risks has been developed. It serves to conceptualize the three perspectives and the three levels where it is possible to take action against risks/problems. Papers II and IV are detailed studies of more narrow issues compared to the other two more comprehensive studies.In paper (I) we compare three legal and administrative systems of risk management in Sweden, namely those responsible for work environment, environmental protection, and chemicals control. Large differences were found in terms of the organizational structures and the general modi operandi of government activities in the three areas. Many of these differences seem to be the result, not of deliberate choice but rather of the lack of coordination between policy areas. It is concluded that systematic comparisons of experiences from different areas can be helpful in improving the efficiency of risk management.Paper (II) is a case study of how the Government, governmental agencies and private companies acted when a dye stuff and a chemical marking agent were introduced to the Swedish market. Their activities are compared to the Swedish act and ordinance on chemical products. The introduction of these chemicals was given big attention in the Swedish newspapers and other media during the winter of 1993/94 when several health problems were reported and related to these substances. It is concluded that the introduction of the chemicals did not comply with the Swedish chemicals legislation. The responsibility to make risk assessments and the reversed burden of proof principle are two fundamental bases of the legislation which were set aside. It is also concluded that the unusual actions and role of the Government in this decision process may explain the actions and positions of the authorities and the companies.Paper (III) is a decision-theoretical study of an extraordinary complex risk management and decision problem - the threat of an anthropogenic climate change. The problem involves a multitude of both natural and social causal factors and a large amount of scientific uncertainty. We found that the method used in all economic decision-studies of global warming that we are aware of is more risk-taking than the standard method used in risk analysis - the expected utility method. We argue that more attention should be paid in the scientific community to less probable but more serious effect scenarios and that a less risk-taking method of analysis should be used. We also argue that the standard method of discounting future costs is inadequate, misleading, and probably not consistent with the concept of sustainable development. We conclude that the principle of sustainable development, the scientific uncertainty, the risk of irreversible damages and the long time lag from negotiations to the point in time when most of the reversible damages will be gone, all together imply that we should reduce anthropogenic emissions of greenhouse gases and that we should act as soon as possible.Paper (IV) examines reasons for and the importance of analysing worst case scenarios and surprises in the area of anthropogenic climate change. Three main reasons are given for assuming that a worst case scenario may be realised: 1) The unpredictibility of the climate system, 2) historical experiences, and 3) conceivable severe scenarios and mechanisms. Although the uncertainty of surprises is huge by definition, and the probability of worst case scenarios cannot be assessed, there are reasons for and ways of incorporating them into the risk analysis. Not including them in the analysis could very well mean that the largest risk is excluded and that decision makers make a more risk-taking decision than they would otherwise have made. However, the IPCC (Intergovernmental panel on climate change) have avoided analysis of the possibility of worst case scenarios and major factors that could give rise to such scenarios. Possible reasons why the IPCC have not included them in their analysis are discussed.
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| 6. |
- Nolin, Catharina, 1962-
(författare)
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Till stadsbornas nytta och förlustande : Den offentliga parken i Sverige under 1800-talet
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this dissertation is to study the public parks in Sweden during the nineteenth century. It focuses on three general factors – decision process, design, and function – and is to a great extent based on previously unstudied material including town councils' minutes, drawings, and other contemporary sources. The dissertation considers a selection of the approximately one hundred public parks laid out in Sweden during the period.From the beginning of the century the middle classes endeavoured to create meeting places and social customs of their own, and public parks had a role to play in their efforts. There, families could spend their leisure time together, meeting acquaintances and amusing themselves. The park was also an aesthetic element in the townscape. The study shows that the first public parks appeared in the 1820s, and that they were established several decades earlier than is generally acknowledged. During the decades following 1860, a large number of new parks were made. From now on, moral considerations began being put forward as grounds for creating public parks. They were promoted as more suitable social settings than the streets, squares, and pubs – for the middle classes as well as for the workers. In the 1890s, new parks were made whose design and function differed distinctly from their predecessors. They were planned for active use to a much greater extent, with features such as games and sport, and all surfaces open to the public. The study also shows that town councils from the beginning of the century were involved in creating the parks, and generally assumed full economic responsibility.Concerning the design, the parks changed during the century. From the initial decades, the essential design assumption was that parks would be perceived as art rather than nature. It should be obvious that the trees, bushes, and flowers did not grow natural on the spot, an impression emphasised by their varied colours, shapes, and ways of growing. Exotic plants were used extensively. From around 1870 the attempt to imitate nature as closely as possible, often using an existing natural area as a starting point and employing indigenous plants, gradually became common.Previous studies have often pointed to the public parks' role in improving the hygiene in the towns, locating them within an overall town planning perspective. However, the study shows that the belief that they might also improve the moral and general living conditions of urban dwellers has been an even more important factor. The park was envisaged as a place of education and general cultivation, but also as a place for amusement, which was reflected in the bandstands, monuments, and playgrounds, etc. Though the parks were often smaller than their counterparts abroad, Sweden was in step with the rest of Europe.
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| 9. |
- Stehr, Micael
(författare)
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Adhesion to machined and laser ablated wood surfaces
- 1999
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis is a contribution to the R&D-program ValueActivation at KTH,Division of Wood Technology and Processingand containsfive papers related to the evaluation and development ofmachining techniques (mechanical and irradiation treatments)whereby weak boundaries at the wood surfaces in the form of(mechanical) weak boundary layers and (micro) cracks due tomechanical treatment can be avoided.The first paper describes the development of a method–using a UV laser–to study the mechanically weakenedboundaries. The purpose is to achieve a sample preparationtechnique for microscopy that minimizes artefacts.Scientifically, the second, third and fourth papers,concerning the interaction between wooden surfaces andsynthetic polymers, are based on the relatively modern adhesiontheory (at least in the field of wood adhesion science) of weakboundary layers. The papers introduce and evaluate the(mechanical) weak boundary layers in relation to wood adhesionscience. The first of these three papers provides thetheoretical basis for the following two. The paper suggests adivision of the weak boundary layer concept into chemical(CWBL) and mechanical (MWBL) weak boundary layers. Thesubsequent two papers evaluate the influence on the glue jointstrength of a reduction in the (mechanical) weak boundarylayer.The last paper deals with (tip-)cracks on a wood surface dueto machining.The results presented in the first paper can be used toachieve samples for microscopic investigations with a minimizednumber of artefacts. The results presented in the fourth papercould be utilized to achieve stronger adhesive joints. Withhelp of a laser ablation technique, it is shown that the "lawof nature" saying that end-grain surfaces cannot be glued ismaybe not so obvious. Methods of eliminating or reducing theweak boundaries have been identified. The results indicate thatit is the adhesive itself that is the weak point in anend-grain joint.It is also possible that the laser ablation techniqueapplied on flat sides could lead to better adhesion between acoating and wood, and the results presented in the last papercould increase the adhesive performance particularly related tocoatings.
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