| 1. |
- Bengtsson, Peter, 1974-, et al.
(författare)
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Evaluation of hydrocarbon emissions from heart- and sapwood of Scots pine using a laboratory-scale wood drier
- 2004
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Ingår i: Holzforschung. - : Walter de Gruyter. - 1437-434X .- 0018-3830. ; 58:6, s. 660-665
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Tidskriftsartikel (refereegranskat)abstract
- The subject of study is the emission of Volatile Organic Compounds (VOC) during the drying of wood. Heartwood and sapwood from Scots pine were dried at different temperatures (50, 70 and 90°C) in a laboratory kiln. The sampling method, Solid Phase Microextraction was used to collect the different volatile organic compounds during the drying. The gas chromatograph and mass spectrometer was used to identify and quantify the organic matter. The total hydrocarbons were measured with a flame ionization detector. Primarily, different monoterpenes were released during the drying process. 3-carene and α-pinene were most common and were also analytically quantified. The diterpene, pimaral, was found in an estimated large amount in the later stage of the drying process but was not exactly quantified. Large differences in both release behaviour and total amount of released hydrocarbon between heart- and sapwood were obtained. Emissions of VOC from heartwood were of a magnitude approximately three times higher than that from sapwood.
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| 2. |
- Blixt Wojciechowski, Anita, et al.
(författare)
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Migratory capacity of the cell line RN33B and the host glial cell response after subretinal transplantation to normal adult rats
- 2004
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Ingår i: Glia. - : John Wiley & Sons. - 0894-1491 .- 1098-1136. ; 47:1, s. 58-67
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Tidskriftsartikel (refereegranskat)abstract
- As previously reported, the brain-derived precursor cell line RN33B has a great capacity to migrate when transplanted to adult brain or retina. This cell line is immortalized with the SV40 large T-antigen and carries the reporter gene LacZ and the green fluorescent protein GFP. In the present study, the precursor cells were transplanted to the subretinal space of adult rats and investigated early after grafting. The purpose was to demonstrate the migration of the grafted cells from the subretinal space into the retina and the glial cell response of the host retina. Detachment caused by the transplantation method was persistent up to 4 days after transplantation, and then reattachment occurred. The grafted cells were shown to migrate in between the photoreceptor cells before entering into the plexiform layers. Molecules involved in migration of immature neuronal cells as the polysialylated neural cell adhesion molecule (PSA-NCAM) and the collapsing response-mediated protein 4 (TUC-4) was found in the plexiform layers of the host retina, but not in the grafted cells. The expression of the intermediate filaments GFAP, vimentin, and nestin was intensely upregulated immediately after transplantation. A less pronounced upregulation was observed on sham-operated animals. In summary, the RN33B cell line migrated promptly posttransplantation and settled preferably into the plexiform layers of the retina, the same layers where the migration cues PSA-NCAM and TUC-4 were established. In addition, both the transplantation method per se and the implanted cells caused an intense glial cell response by the host retina.
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| 3. |
- Blixt Wojciechowski, Anita, et al.
(författare)
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Survival and long distance migration of brain-derived precursor cells transplanted to adult rat retina
- 2004
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Ingår i: Stem Cells. - : AlphaMed Press. - 1549-4918 .- 1066-5099. ; 22:1, s. 27-38
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Tidskriftsartikel (refereegranskat)abstract
- Neural precursor cells transplanted to adult retina can integrate into the host. This is especially true when the neural precursor rat cell line RN33B is used. This cell line carries the reporter genes LacZ and green fluorescent protein (GFP). In grafted rat eyes, RN33B cells are localized from one eccentricity to the other of the host retina. In the present study, whole-mounted retinas were analyzed to obtain a more appropriate evaluation of the amount of transgene-expressing cells and the migratory capacity of these cells 3 and 8 weeks post-transplantation. Quantification was made of the number of beta-galactosidase- and GFP-expressing cells with a semiautomatized stereological cell counting system. With the same system, delineation of the distribution area of the grafted cells was also performed. At 3 weeks, 68% of the grafted eyes contained marker-expressing cells, whereas at 8 weeks only 35% of the eyes contained such cells. Counting of marker-expressing cells demonstrated a lower number of transgene-expressing cells at 3 weeks compared with 8 weeks post-transplantation. The distribution pattern of marker gene-expressing cells revealed cells occupying up to 21% at 3 weeks and up to 68% at 8 weeks of the entire host retina post-grafting. The precursor cells survived well in the adult retina although the most striking feature of the RN33B cell line was its extraordinary migratory capacity. This capability could be useful if precursor cells are used to deliver necessary genes or gene products that need to be distributed over a large diseased area.
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| 4. |
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| 5. |
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| 6. |
- Cijvat, Ellie, et al.
(författare)
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CMOS Transceiver Front-Ends in Mobile Communication Handsets : Architectures and Building Blocks
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For mobile communication systems in the low-GHz range, CMOS has increasingly become the technology of choice, and the level of integration in mobile handsets has risen. The use of off-chip components, which increases the handset assembly time and costs, is preferably avoided. However, integrating a complete transceiver on a single chip leads to disturbances between building blocks. This imposes new and more stringent requirements on building block and transceiver performance, as well as impacts the choice of transceiver architecture.In the general introduction, an overview is given of front-end receiver and transmitter aspects as well as RF CMOS technology. This includes the impact of mobile communication system specifications on architectures and building blocks, transistor and monolithic inductor modeling, and disturbance issues. Special attention is given to power amplifiers, the most challenging building blocks in CMOS transceivers. Papers I, II and III address CMOS receiver front-end aspects and implementations, while in papers IV and V design and challenges of CMOS power amplifiers are described.
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| 7. |
- Elsrud, Torun
(författare)
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Taking Time and Making Journeys : Narratives on Self and the Other among Backpackers
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This work addresses the phenomenon of long-term, so-called ‘independent’ travelling, or backpacking, often to destinations described as the ‘third world’. It regards backpacker journeys as arenas for identity work, for expressing individuality and a ‘strong character’. Rather than merely being a parenthetic detour in time and space a backpacker’s trip to the tropics can be understood as a creative effort by the individual to regain the control over time and space thought to be lost in places travellers call home. Yet, at the same time, backpacking reproduces structures of power, through (re)constructing the image of a ‘primitive other’ upon which much of a successful ‘western identity’ rests. The success is, however, not only dependent upon inventing and encountering ‘primitive’ others but also upon the gender of the traveller as well as the competence in mastering manifestations of adventure and risk. The work argues, for instance, that stereotype expectations of femininity (and masculinity) make female ‘adventurism’ into a challenge beyond the actual (or faked) ordeals encountered on the road. Adventurous women are forced to negotiate and balance between expectations placed upon them as (non-adventurous) females and as adventurous travellers. The arguments rest upon the ontological and epistemological conviction that individuals are creative, making the most out of the tools for identity work which society supplies them with. However, in the process of individual self-articulation, structures are both maintained and altered. Consequently, it is through studying individuals and their products/expressions (such as media texts or choice of clothing, food or ‘proper’ transport) that information can be gathered concerning individual thoughts and actions and the structures within which these are manifested. Such an undertaking has been accomplished within this project by means of a qualitative, ethnographically influenced approach, including interviews with backpackers, observations in backpacker areas and analysis of travel media.
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| 8. |
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| 9. |
- Engström, Christian, et al.
(författare)
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A Comparison of two numerical methods for homogenization of Maxwell's equations
- 2004
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Ingår i: Computational Electromagnetics- Methods and Applications (EMB04), Gothenburg, Sweden, October 18-19, 2004. ; , s. 50-57
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Konferensbidrag (refereegranskat)abstract
- When the wavelength is much larger than the typical scale of the microstructure in a material, it is possible to define effective or homogenized material coefficients. The classical way of determination of the homogenized coefficients consists of solving an elliptic problem in a unit cell. This method and the Floquet-Bloch method, where an eigenvalue problem is solved, are numerically compared with respect to accuracy and contrast sensitivity. The Floquet-Bloch method is shown to be a good alternative to the classical homogenization method, when the contrast is modest.
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| 10. |
- Engström, Christian, et al.
(författare)
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Numerical methods for homogenization of Maxwell's equations
- 2004
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Ingår i: URSI 2004 International Symposium on Electromagnetic Theory. - : Pisa University Press. - 8884922526 - 9788884922526 ; , s. 987-989
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Konferensbidrag (refereegranskat)abstract
- When the wavelength is much larger than the typical scale of the microstructure in a material, it is possible to define effective or homogenized material coefficients. Two numerical methods for the determination of the homogenized coefficients are compared. Numerical examples, where extreme properties of the effective material are achieved in the two dimensional case, are presented.
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