| 55501. |
- von Koss Torkildsen, Janne, et al.
(författare)
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Electrophysiological correlates of auditory semantic priming in 24-month-olds.
- 2007
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Ingår i: Journal of Neurolinguistics. - : Elsevier BV. - 0911-6044. ; 20:4, s. 332-351
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Tidskriftsartikel (refereegranskat)abstract
- While the N400 component in adults is sensitive to both semantic incongruity and semantic relatedness between stimulus items, the N400 in toddlers has only been shown as an incongruity effect so far. The present event-related potential (ERP) study aimed to investigate whether the N400 in toddlers also indexes semantic relatedness between single words. To address this issue, we developed a unimodal auditory experiment with semantically related and unrelated word pairs, comparable to behavioral semantic priming tasks used with adults. In 24-month-old children, target words which were preceded by a semantically unrelated word elicited a broadly distributed N400-like effect compared to target words which were primed by a semantically related word. For related words, toddlers displayed a negativity in the 200–400ms interval, indicating facilitated lexical-phonological processing. Results of the present study suggest that the N400 in toddlers is functionally equivalent to the adult component in indexing relatedness as well as semantic incongruity between stimulus items. Moreover, the study demonstrates an instrument for investigating semantic relatedness priming in young children, for whom behavioral tasks are often inappropriate.
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| 55502. |
- von Kraemer, Sophie, et al.
(författare)
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Evaluation of high temperature membrane electrode assemblies based on sulfonated polysulfones
- 2007
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Ingår i: Proceedings of the Second European Fuel Cell and Applications Conference. ; EFC2007-39251:TK 1 Material and Fabrication Processes
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Konferensbidrag (refereegranskat)abstract
- In the development and evaluation of alternative ionomers, the membrane development and ex situ characterization have been the focus of interest. The properties of a MEA are dependent on the composition of materials in the components, i.e. membrane, electrodes and gas diffusion layers, and the interaction between these parts. The complexity of water transport in different components is one example of why new ionomers should be studied in complete MEAs. The importance of research on Gas Diffusion Electrodes (GDEs) based on new ionomers has been emphasized before, however, the incorporation of novel ionomers in GDEs has been reported only recently. In addition, it has been stated that high interfacial resistances occur between novel membranes and state-of-the-art Nafion GDEs, which will result in early MEA degradation and methodological difficulties in membrane lifetime testing.
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| 55503. |
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| 55504. |
- von Porat, Anette
(författare)
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Knee function, movement pattern and knee osteoarthritis in males 14-16 years after an anterior cruciate ligament injury
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this work was to study knee function movement pattern and knee osteoarthritis in males 14-16 years after anterior cruciate ligament (ACL) injury. In the first study, 154 male subjects with a 14-year-old ACL injury were investigated. Self-reported knee function and radiographic signs of osteoarthritis were assessed. Most of the subjects (122/154) underwent knee radiographs, 78% of which showed radiographic changes. The prevalence of tibio-femoral knee osteoarthritis (OA) was 41%. Fourteen years after the ACL injury the self-reported knee function was worse than in healthy subjects. In the second and third studies 12 male subjects with a 16-year-old ACL injury and 12 matched healthy references were investigated. In Study II, the kinetics and kinematics of three functional tests: gait, step activity and cross-over hop, of the 12 ACL-injured subjects (a geographically determined subgroup from Study 1) and the 12 matched reference were compared. The self-reported knee functions of the two groups were also compared. No detectable differences were found in the kinetics and kinematics of the ACL-injured subjects and their matched reference. The self-reported knee function among ACL-injured subjects was, however, worse than that among non-injured subjects. In the third study, an intervention programme consisting of knee-specific exercises, once a week for twelve weeks, was applied to the subjects with an ACL injury. After twelve weeks of training, both under supervision and at home, motion analysis of the injured subjects showed results closer to those of the healthy controls, and self-reported knee function had improved. The fourth study was carried out to determine the reliability and validity of the functional performance tests: gait, knee bending, step activity, cross-over hop and one-leg hop. Four physiotherapists were used as observers. The physiotherapists assessed the knee function of the subjects with an ACL injury before and after the training period using video sequences. The reliability between the physiotherapists was relatively good and the validity of the functional performance tests when compared with the motion analysis data was acceptable. Based on the results presented in this thesis, it can be concluded that the prevalence of tibio-femoral knee osteoarthritis, 14 years after an ACL injury, is high, and that self-reported knee function is affected, despite the long time since injury. No differences in motion analysis results could be seen between injured subjects and references; however a type II error could not be ruled out. Knee-specific training for twelve weeks decreased knee stiffness and improved self-reported knee function. The moderate to good reliability and the acceptable validity found indicate that the presence of knee stiffness in subjects with an ACL injury can be determined by visual observation of more demanding functional tests.
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| 55505. |
- Vressner, Andreas
(författare)
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Studies on the Load Range of an HCCI Engine using In-Cylinder Pressure, Ion Current and Optical Diagnostics
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Internal combustion engines are continuously developed towards decreased hazardous emissions and lower fuel consumption. The homogeneous charge compression ignition (HCCI) engine is a promising concept which combines the best features of the Diesel engine and the spark ignition (SI) engine. The efficiency is in the range of the Diesel engine and the emissions are low and comparable to the emissions from an SI engine with catalyst. No flame propagation is present in the HCCI engine; instead the whole charge is gradually consumed at several locations simultaneously. The resulting pressure rise rate is therefore high which means that the engine has to be run lean or diluted with burned gases in order not to stress the mechanical parts of the engine or produce excessive noise. Due to the lean and diluted mixtures the combustion temperature is low and fairly uniform. This results in low emissions of NOx and PM but if the temperature is too low emissions of unburned hydrocarbons and carbon monoxide (CO) increase. Furthermore, the pressure rise rate limits HCCI combustion to low or part load and is therefore to be combined with either Diesel or SI operation at higher loads. In this thesis different diagnostic methods have been used to study the HCCI combustion process at different engine loads. Combustion diagnostics have been performed using cylinder pressure and ion current measurement as well as optical techniques such as chemiluminescence imaging. By pressure measurement the overall combustion behaviour in the cylinder can be studied. By ion current measurement local conditions in small volumes can be studied. This is of interest since there are differences in temperature and relative air/fuel ratio between different locations in the combustion chamber. Locations with higher temperature or richer mixtures ignite first and this affects the ongoing combustion cycle. Pressure diagnostics is accurate but expensive as feedback method of the ongoing combustion process. Ion current diagnostics is cheap but due to the low temperature nature of HCCI combustion it is only usable at higher engine loads and thus the method is not an option for low load or idle conditions. Different fuels will provoke ion current differently for the selected compression ratio, initial charge temperature, measuring location and relative air/fuel ratio. If the initial charge temperature is too low, partial or total misfire might occur. At these running conditions spark or laser assistance can be used to increase the charge temperature prior to auto ignition. This advances the combustion phasing, thus minimizing the risk of misfire. This is also interesting for control purposes since it is possible to control the HCCI combustion phasing by changing the spark or laser ignition timing. When running laser assisted HCCI, flame propagation is present from the laser ignition location and, as the pressure and temperature increase, auto ignition occurs. This operation is a mixed mode of flame propagation and auto ignition. Lastly the effect of combustion chamber geometry on HCCI combustion rate was studied. A square bowl in piston geometry compared to Disc geometry showed the possibility to extend the maximum load limit due to decreased pressure rise rates but at the cost of decreased engine efficiency. Chemiluminescence and LIF imaging as well as LES showed stratified combustion behaviour unusual for HCCI operation which normally is a more homogeneously distributed combustion process.
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| 55506. |
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| 55507. |
- Vulovic, Jimmy, et al.
(författare)
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Det demokratiska uppdraget
- 2007
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Ingår i: Kulturjournalistikens grunder. - 9789144019581 ; , s. 103-106
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 55508. |
- Vulovic, Jimmy, et al.
(författare)
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Ett uppror mot liv och död
- 2007
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Ingår i: Att granska och diskutera: Lyrikanalyser. - 9789144046686 ; , s. 95-99
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 55509. |
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| 55510. |
- Vulovic, Jimmy, et al.
(författare)
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Romanrecensionen
- 2007
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Ingår i: Kulturjournalistikens grunder. - 9789144019581 ; , s. 71-101
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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