| 1. |
- Bladh, Henrik, et al.
(författare)
-
Influence of Soot Particle Aggregation on Time-Resolved Laser-Induced Incandescence Signals
- 2011
-
Ingår i: Applied Physics B. - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 104:2, s. 331-341
-
Tidskriftsartikel (refereegranskat)abstract
- Laser-induced incandescence (LII) is a versatile technique for quantitative soot measurements in flames and exhausts. When used for particle sizing, the time-resolved signals are analysed as these will show a decay rate dependent on the soot particle size. Such an analysis has traditionally been based on the assumption of isolated primary particles. However, soot particles in flames and exhausts are usually aggregated, which implies loss of surface area, less heat conduction and hence errors in estimated particle sizes. In this work we present an experimental investigation aiming to quantify this effect. A soot generator, based on a propane diffusion flame, was used to produce a stable soot stream and the soot was characterised by transmission electron microscopy (TEM), a scanning mobility particle sizer (SMPS) and an aerosol particle mass analyzer coupled in series after a differential mobility analyzer (DMA-APM). Despite nearly identical primary particle size distributions for three selected operating conditions, LII measurements resulted in signal decays with significant differences in decay rate. However, the three cases were found to have quite different levels of aggregation as shown both in TEM images and mobility size distributions, and the results agree qualitatively with the expected effect of diminished heat conduction from aggregated particles resulting in longer LII signal decays. In an attempt to explain the differences quantitatively, the LII signal dependence on aggregation was modelled using a heat and mass transfer model for LII given the primary particle and aggregate size distribution data as input. Quantitative agreement was not reached and reasons for this discrepancy are discussed.
|
|
| 2. |
- Edfeldt, Lennart, et al.
(författare)
-
Evaluation of cost-utility in middle ear implantation in the 'Nordic School' : a multicenter study in Sweden and Norway
- 2014
-
Ingår i: Acta Oto-Laryngologica. - : Informa UK Limited. - 0001-6489 .- 1651-2251. ; 134:1, s. 19-25
-
Tidskriftsartikel (refereegranskat)abstract
- Conclusion: Hearing restoration using an active middle ear implant (AMEI) is a highly cost-effective treatment for a selected group of patients with no other possibilities for auditory rehabilitation. Objectives: To evaluate the cost-utility of using an AMEI for hearing rehabilitation. Methods: This was a prospective, multicenter, single-subject repeated study in six tertiary referral centers. Twenty-four patients with sensorineural (SNHL), conductive (CHL), and mixed hearing loss (MHL) were implanted with the AMEI Vibrant Soundbridge (R) (VSB) for medical reasons. All patients were previously rehabilitated with conventional hearing aids. Multiple validated quality of life patient questionnaires, Health Utilities Index (HUI 2 and 3), and Glasgow Hearing Aid Benefit Profile (GHABP) were used to determine the utility gain and quality adjusted life years (QALY). Directly related treatment costs for the implantation were calculated and related to utility gain and QALY. Results: The cost/QALY for patients with SNHL was estimated at (sic)7260/QALY, and for patients with C/MHL at (sic)12 503/QALY.
|
|
| 3. |
|
|
| 4. |
- Segerholm, Christina, 1956-, et al.
(författare)
-
Changing evaluation systems – changing expectations? The case of Swedish higher education
- 2014
-
Ingår i: Symposium Governing by Expectations: School Inspection and Evaluation across Europe and Beyond.
-
Konferensbidrag (refereegranskat)abstract
- As a part of the ‘audit society’ (Power 1997), the idea of systematic evaluations is strongly promoted in contemporary education policy (Ozga et al. 2011). Higher education is not an exception and European policy like the Bologna declaration and the development of common quality indicators are just a few examples. Looking at the national arena, this paper aims at exploring the relation between evaluation systems in Swedish higher education and governing from 1993 and onwards. Theoretically we recognize the dynamic relationship underling both institutional reproduction and change (Mahoney & Thelen 2010). Evaluation systems may change gradually or more dramatically and these dynamics hold implications for governing and for how we can understand expectations of what is to count as, for instance, as ‘good quality’ Hopmann et al. 2007). Official policy texts are used and a qualitative content analysis (Bergström & Boréus 2005) is performed, guided by questions like: What is evaluated? Why? By whom? How? With what consequences? The results suggest that the governing potential in the evaluation systems in higher education in the Swedish case partly relies on the shifts themselves. By constantly changing the systems, expectations are also changed and form one important part of the work of governing.
|
|
| 5. |
- Taghavi, Hamidreza, 1981, et al.
(författare)
-
A vibration investigation of a flat surface contact to skull bone for direct bone conduction transmission in sheep skulls in vivo.
- 2013
-
Ingår i: Otology & neurotology : official publication of the American Otological Society, American Neurotology Society [and] European Academy of Otology and Neurotology. - 1537-4505 .- 1531-7129. ; 34:4, s. 690-8
-
Tidskriftsartikel (refereegranskat)abstract
- Hypothesis: Bone conduction implant (BCI) attached with a flat surface contact will offer efficient and linear vibration transmission over time. Background: Despite that percutaneous bone conduction devices (PBCD) are successful in treating patients with conductive hearing loss, there are some drawbacks related to the need of a permanent skin penetration. The BCI system is designed as an alternative to the PBCD because it leaves the skin intact. Methods: BCI dummy implants were installed in 3 sheep skulls in vivo to study the vibration transmission characteristics over time. Mechanical point impedances and vibration transfer response functions of the BCI implants were measured at the time of surgery and after a healing period of 8 months. Results: In 1 sheep both implants healed without complications. In the other 2 sheep, the implants were either partially loose or lost to follow up. In the sheep with stable implants, it was found by the resonance frequency shift of the mechanical point impedance that a firmer integration between the implant and bone tissue as seen in osseointegrated surfaces developed over time. It was also shown that the transcranial vibration transmission remains stable and linear. Providing bone chips in the contact between the implant and the bone did not enhance vibration transmission. The surgical procedure for installing the BCI dummy implants was uneventful. Conclusion: The mechanical point impedances and vibration transfer response functions indicate that the BCI implants integrate and that transmission conditions remain stable over time.
|
|
| 6. |
- Östergren, Rickard, 1975-
(författare)
-
Mathematical Learning Disability : Cognitive Conditions, Development and Predictions
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of the present thesis was to test and contrast hypotheses about the cognitive conditions that support the development of mathematical learning disability (MLD). Following hypotheses were tested in the thesis: a) domain general deficit, the deficit is primarily located in the domain general systems such as the working memory, b) number sense deficit, the deficit is located in the innate approximate number system (ANS), c) numerosity coding deficit, the deficit is located to a exact number representation system, d) access deficit, the deficit is in the mapping between symbols and the innate number representational system (e.g., ANS), e) multiple deficit hypothesis states that MLD could be related to more than one deficit.Three studies examined the connection between cognitive abilities and arithmetic. Study one and three compared different groups of children with or without MLD (or risk of MLD). Study two investigated the connection between early number knowledge, verbal working memory and the development of arithmetic ability.The results favoring the multiple deficit hypothesis, more specifically the result indicate that number sense deficit together with working memory functions constitutes risk-factors to the development of MLD in children. A simple developmental model that is based on von Asters and Shalev´s (2007) model and the present results is suggested, in order to understand the development of MLD in children.
|
|
