| 1. |
- Dahlgren, Anders, et al.
(författare)
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Planning Rescue Services with Non-Stationary Rescue Units
- 2009
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Ingår i: Fire Technology. - : Springer Science and Business Media LLC. - 0015-2684 .- 1572-8099. ; 45:3, s. 239-255
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Tidskriftsartikel (refereegranskat)abstract
- Geographical accessibility is fundamental when planning rescue services. At present there are several programs for computing the accessibility of stationary rescue units. This study suggests a method for evaluating geographic accessibility in scenarios containing also non-stationary units. The method supports the planning process by matching the risk of an incident occurring with the rescue units’ capabilities and accessibility. The method is implemented in the computer program Rescue Unit Planner. The result of the analysis is presented in thematic maps and graphs as level of coverage, mean response time and concentration. The method and the computer program have been evaluated in two case studies: one urban area in southern Sweden and one rural area in northern Sweden. The case studies show that that this method can be useful in the rescue service planning process.
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| 2. |
- Lagerkvist, Claes-Ingvar, et al.
(författare)
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A study of Cybele asteroids
- 2005
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Ingår i: Astron.&Astrophys 432. ; , s. 349-354
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 3. |
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| 4. |
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| 5. |
- Dahlgren, Anders, et al.
(författare)
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Development of a tool for proximity applications
- 2007
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Ingår i: Proceedings of the 10th AGILE International Conference on Geographic Information Science.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 6. |
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| 7. |
- Dahlgren, Anders
(författare)
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Geographic Accessibility Analysis - Methods and Application
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Geographic accessibility to services is important. Having a grocery store and a school nearby are important living conditions and having a rescue station close by could be a life-saver. Costs for transportation are high and are predicted to increase, new environmental demands are being imposed on transportation and rationalizations are centralizing public and commercial services. These facts make monitoring and planning accessibility increasingly important. Efficient computer systems for accessibility monitoring and planning could be used to improve accessibility to services. The aim of this study is to establish such efficient methods for geographic accessibility analysis and test them in computer applications. This was performed by studying effective ways of structuring data, algorithms for network searches and implementing these theories in test benches and application prototypes. Geographic accessibility to services is essential, especially when long distances must be covered, as in rural areas. The Swedish National Rural Development Agency (SNRDA) analyses accessibility to services from a national perspective, with the focus on rural areas. This is done using a computer model that is implemented in a Geographical Information System (GIS). This study investigates the foundations of the representation of road networks, connecting points to a network and accessibility studies through network searches. The results of this dissertation are meant to be used to develop the next generation of the system. Three papers are presented in this dissertation. The first deals with an evaluation of an existing accessibility analysis system at the Swedish National Rural Development Agency. The focus of the study was to identify performance bottlenecks in the SNRDA’s accessibility system and the problem areas that were found would then guide further research. One of the bottlenecks found in the study was the process of connecting points to large networks. This is investigated in the second paper and suggestions for solutions of the problem are presented. The third study is an applied study for planning accessibility to rescue services. This study concentrates on an application prototype called the Rescue Unit Planner (RUP) used for planning accessibility for non-stationary rescue units. The conclusions of this dissertation are that it is possible to build more efficient systems to perform accessibility analysis. The studies in this dissertation will support the further development of the SNRDA accessibility analysis system, which also was the overall goal.
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| 8. |
- Dahlgren, Christina Vallhagen, et al.
(författare)
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Portal dose image verification : the collapsed cone superposition method applied with different electronic portal imaging devices.
- 2006
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Ingår i: Physics in Medicine and Biology. - 0031-9155. ; 51:2, s. 335-49
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Tidskriftsartikel (refereegranskat)abstract
- Two different commercial electronic portal imaging devices (EPIDs), one based on a liquid ion chamber matrix and the other based on a fluoroscopic CCD camera, were used to acquire readings that, through a calibration procedure, provided images proportional to the absolute dose to a virtual water slab located at the EPID plane. The transformation of the matrix ion chamber image into a portal dose image (PDI) was based on a published relationship between dose rate and ionization current. For the fluoroscopic CCD-camera-based system, the transformation was based on a deconvolution with a radial light scatter kernel. Local response variations were corrected in the images from both systems using open field fluence maps. The acquired PDIs were compared with PDIs calculated with the collapsed cone superposition method for a three-dimensional detector model in water equivalent buildup material. The calculation model was based on the beam modelling and geometrical description of the treatment unit and energy used for treatment planning in a kernel-based system. The validity of the calculation method was evaluated for several field shapes and thicknesses of patient phantoms for the matrix ion chamber at 6 MV x-rays and for the camera-based EPID at 6 and 15 MV x-rays. The agreement between predicted and measured PDIs was evaluated with dose comparisons at points of interest and gamma index calculations. The average area failing the passing criteria in dose and position deviation was analysed to validate the performance of the method. For the matrix ion chamber on average an area less than 1% fails the passing criteria of 3 mm and 3%. For the camera-based EPID, the average area is 7% and 1% for 6 and 15 MV, respectively. The overall agreement centrally in the fields was 0.1 +/- 1.6% (1 sd) for the camera-based EPID and -0.1 +/- 1.6% (1 sd) for the matrix ion chamber. Thus, an absolute dose calibrated EPID could validate the delivered dose to the patient by comparing a calculated and a measured PDI.
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| 9. |
- Dahlgren, Eva, et al.
(författare)
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Sertoli-Leydig cell tumour in a postmenopausal woman showing all facets of the insulin resistance syndrome (IRS)
- 2005
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Ingår i: Ups J Med Sci. - 0300-9734. ; 110:3, s. 233-6
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Tidskriftsartikel (refereegranskat)abstract
- Sertoli-Leydig cell tumours are rare sex stromal tumours with an incidence of < 0.5% of all ovarian tumours. Most frequently this tumour occurs in young women with a history of amenorrhoea, hirsutism and lowered pitch. Here, we report on a woman with IRS, postmenopausal virilization and increased testosterone levels due to a Sertoli-Leydig cell tumour. This is the first case to suggest an association between IRS and Sertoli-Leydig cell tumours. Furthermore, we highlight the difficulties in detecting this ovarian tumour with sonography.
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| 10. |
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