| 1. |
- Laux, M., et al.
(författare)
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Arcing at B4C-covered limiters exposed to a SOL-plasma
- 2003
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Ingår i: Journal of Nuclear Materials. - 0022-3115 .- 1873-4820. ; 313, s. 62-66
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Tidskriftsartikel (refereegranskat)abstract
- Plasma sprayed B4C-layers considered as wall coatings for the W7X stellarator have been studied during and after exposure to TEXTOR and after arcing experiments in vacuum. Arcing through the B4C layer occurred favoured by high power fluxes and not restricted to less stable phases. But this arcing implies an especially noisy scrape-off layer (SOL). Instead of moving retrograde in the external magnetic field, the arc spot on the B4C-layer sticks to the same location for its whole lifetime. Consequently, the arc erodes the entire B4C layer, finally burning down to the Cu substrate. In the neighbourhood of craters the surface contains Cu originating from those craters. This material, hauled to the surface by the arc, is subject to subsequent erosion, transport, and redeposition by the SOL-plasma. The behaviour of arcs on B4C is Most probably caused by the peculiar temperature dependences of the electrical and heat conductivity of B4C.
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| 2. |
- Machungo, F, et al.
(författare)
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Syphilis, gonorrhoea and chlamydial infection among women undergoing legal or illegal abortion in Maputo
- 2002
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Ingår i: International Journal of STD and AIDS. - : SAGE Publications. - 0956-4624 .- 1758-1052. ; 13:5, s. 326-330
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Tidskriftsartikel (refereegranskat)abstract
- Our objectives were to compare the prevalence of sexually transmitted infections (STIs) in 103 women undergoing induced legal abortion (LA) and in 101 women with confirmed, recent illegal abortion (IA), in Maputo, Mozambique. For the purpose of this study, LA was considered the abortion provided in the Maputo Central Hospital with the approval of the Ministry of Health, and IA the one not provided through the approved facility, mentioned above. Women with IA were recruited in the outpatient gynaecology ward and women with LA in the emergency gynaecology ward in the Maputo Central Hospital, during the same time period. Serological tests for syphilis (rapid plasma reagin, ELISA-IgC and fluorescent treponemal antibody absorption), gonorrhoea (indirect haemagglutination) and chlamydia (microimmunofluorescence) were carried out. Direct immuno-fluorescence for detection of Chlamydia trachomatis antigen was done on endocervical smears from all the women. The prevalence of syphilis seropositivity in IA women is twice that of LA women (odds ratio [OR] 2.13; 95% confidence interval [CI] 0.55-9.95), with 10.9% and 4.9%, respectively. Exposure to gonorrhoea in these 2 groups is similar (OR 1.18; 95% CI 0.63-2.20), with seroprevalence of 31.1% in the LA and 34.7% in the IA group. The high titres are also similar in both groups. Serology findings for C. trachomatis indicate prevalence of seropositivity of 40.6% in the LA and 44.4% in the IA group with no significant difference (OR 1.17; 95% CI 0.64-2.13). In conclusion, STIs are highly prevalent in both IA and LA groups in Maputo. Urgent interventions are needed to reduce their prevalence and consequently their adverse consequences.
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| 3. |
- Harraghy, N, et al.
(författare)
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The adhesive and immunomodulating properties of the multifunctional Staphylococcus aureus protein Eap
- 2003
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Ingår i: Microbiology (Reading, England). - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 149:Pt 10, s. 2701-2707
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Tidskriftsartikel (refereegranskat)abstract
- Adherence of Staphylococcus aureus to the host tissue is an important step in the initiation of pathogenesis. At least 10 adhesins produced by S. aureus have been described and it is becoming clear that the expression of these adhesins and their interactions with eukaryotic cells involve complex processes. Some of these, such as the fibronectin-binding proteins (FnBPs) and Clumping Factor A, are well characterized. However, in the last 10 years a number of novel S. aureus adhesins have been described. Functional analyses of these proteins, one of which is Eap (extracellular adherence protein, also known as Map and p70), are revealing important information on the pathogenesis of staphylococcal disease. More than 10 years after the first report of Eap, we are beginning to understand that this protein, which has a broad spectrum of functions, may be a critical factor in the pathogenesis of S. aureus. This review will focus on the interactions of Eap with eukaryotic cells, plasma proteins and the extracellular matrix as well as on the recently recognized role of Eap as an important mediator in the immune response to staphylococcal infection.
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| 4. |
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| 5. |
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| 6. |
- Lanhede, B., et al.
(författare)
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The Influence of Different Technique Factors on Image Quality for Chest Radiographs: Application of the Recent CEC Image Quality Criteria
- 2000
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Ingår i: Radiation Protection Dosimetry. - 1742-3406. ; 90:1-2, s. 203-206
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the first this work part of the EU-project, Trial I, was to evaluate and possibly improve the CEC image criteria for radiographic chest images. Chest images of healthy volunteers were acquired using different technique factors. The image criteria were used as a tool to discriminate between the different images. The technique factors were chosen so that the image quality would differ slightly. Four different technique parameters, each with two possible settings, used in clinical practice today, were used: tube voltage - 102 and 141 kV; screen/film speed - 160 and 320; maximum optical density in the parenchyma - 1.3 and 1.8; method for scatter reduction - air gap 30/390 and moving grid40/12. The results showed that the image criteria were able to separate between different technique groups. Some conclusions can be drawn from the results Optical density 1.8 was better than 1.3 independent of the other parameters. . Among the six combinations ranked best , four used tube voltage 141 kV and four used air gap technique for scatter reduction. No difference was seen for screen/film speed. No correlation was seen between the ranking of the systems and patient dose.
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| 7. |
- Lanhede, B, et al.
(författare)
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The influence of different technique factors on image quality of chest radiographs as evaluated by modified CEC image quality criteria.
- 2002
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Ingår i: The British journal of radiology. - : British Institute of Radiology. - 0007-1285 .- 1748-880X. ; 75:889, s. 38-49
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Tidskriftsartikel (refereegranskat)abstract
- The Commission of the European Communities (CEC) research project "Predictivity and optimisation in medical radiation protection" addressed fundamental operational limitations in existing radiation protection mechanisms. The first part of the project aimed at investigating (1) whether the CEC image quality criteria could be used for optimization of a radiographic process and (2) whether significant differences in image quality based on these criteria could be detected in a controlled project with well known physical and technical parameters. In the present study, chest radiographs on film were produced using healthy volunteers. Four physical/technical parameters were varied in a carefully controlled manner: tube voltage (102 kVp and 141 kVp), nominal speed class (160 and 320), maximum film density (1.3 and 1.8) and method of scatter reduction (grid (R=12) and air gap). The air kerma at the entrance surface was measured for all patients and the risk-related dose H(Golem), based on calculated organ-equivalent dose conversion coefficients and the measured entrance air kerma values, was calculated. Image quality was evaluated by a group of European expert radiologists using a modified version of the CEC quality criteria. For the two density levels, density level 1.8 was significantly better than 1.3 but at the cost of a higher patient radiation exposure. The correlation between the number of fulfilled quality criteria and H(Golem) was generally poor. An air gap technique resulted in lower doses than scatter reduction with a grid but provided comparable image quality. The criteria can be used to highlight optimum radiographic technique in terms of image quality and patient dose, although not unambiguously. A recommendation for good radiographic technique based on a compromise between image quality and risk-related radiation dose to the patient is to use 141 kVp, an air gap, a screen-film system with speed 320 and an optical density of 1.8.
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| 8. |
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| 9. |
- Pospieszczyk, A., et al.
(författare)
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B4C-limiter experiments at TEXTOR
- 2003
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Ingår i: Journal of Nuclear Materials. - 0022-3115 .- 1873-4820. ; 313, s. 223-229
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Tidskriftsartikel (refereegranskat)abstract
- In the TEXTOR tokamak the five top and five bottom poloidal carbon limiter blocks have been replaced by inertially cooled copper blocks coated with a 170 mum VPS-B4C layer. Similar limiter blocks have been inserted through lock systems, extensively diagnosed in situ as well as ex situ. During the thermal load by the plasma, the surface temperature rose and decayed extremely fast which can be explained by a different thermal conductivity and heat capacity of the coating. For heat loads below 8 MW m(-2) no severe cracking or delamination of the B4C-coating were observed. Due to the insulating behaviour of the layer, distinct craters developed on both limiter types, which reached down to the copper surface and are assumed to be caused by electrical arcs. An oscillation of the evolution of the surface temperature has been observed under certain conditions, which is clearly correlated to the use of the coated test limiter. Particle fluxes as well as hydrogen inventory turned out to be very similar to those from a low-Z surface in a carbon surrounding. No significant impact of the plasma on the coating and vice versa was observed.
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| 10. |
- Tingberg, Anders, et al.
(författare)
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Comparison of two methods for evaluation of the image quality of lumbar spine radiographs
- 2000
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Ingår i: Radiation Protection Dosimetry. - 1742-3406. ; 90:1, s. 165-168
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Tidskriftsartikel (refereegranskat)abstract
- Two methods for visual evaluation of image quality of clinical radiographs have been compared. In visual grading analysis (VGA) specified anatomical structures in an image are visually compared with the same structures in a reference image, and in a free-response forced error (FFE) experiment - an extension of conventional ROC (receiver operating characteristics) analysis - the objective is to correctly localise known lesions. The spatial resolution and noise of digitised clinical radiographs of the lumbar spine were altered by image processing, and pathological structures were added to the images for the FFE experiment. The images were printed to film and evaluated by seven European expert radiologists using VGA and FFE. The results of these two different methods showed a very good agreement. In conclusion, VGA methodology can be made as solid as the FFE experiment for evaluating image quality. The simplicity of VGA makes it very suitable for implementation in clinical practice.
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