| 1. |
- Högdahl, Elisabeth
(författare)
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Att omförhandla staden
- 2009
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Ingår i: Kulturella perspektiv. - 1102-7908. ; 18:1, s. 16-29
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Tidskriftsartikel (refereegranskat)abstract
- Artikeln behandlar migrerande kvinnors hantering av platserna de kommer till. Utgångspunkten är hur identitetsmässiga förändringar sker relaterat till platser. Empiriskt utgår artikeln från två kvinnoöden av ganska olika karaktär.
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| 2. |
- Friman, Helena, 1941-
(författare)
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I staden
- 1995
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Ingår i: Kulturmiljövård. - Stockholm : Riksantikvarieämbetet. - 1100-4800. ; :3, s. 51-53
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Ju mer vi vet om vår miljö, vår hembygd eller stad, desto mer värdesätter vi den. Då blir det också lättare för oss att försvara den mot oförstående behandling och förstörelse. Att skolan skall använda staden som kunskapskälla är självklart, men det gäller att rätt utnyttja och lyfta fram det konkreta historiska objektet - staden själv - för att få ungdomarna att öppna ögonen för denna upplevelse.
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| 3. |
- Harrison, Dick
(författare)
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Staden brinner!
- 2015
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Ingår i: Sotaren. - 2002-0856. ; , s. 21-23
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
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| 4. |
- Blicharska, Malgorzata, 1979-, et al.
(författare)
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Steps to overcome the North-South divide in research relevant to climate-change policy and practice
- 2017
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Ingår i: Nature Climate Change. - 1758-678X .- 1758-6798. ; 7, s. 21-27
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Tidskriftsartikel (refereegranskat)abstract
- A global North-South divide in research, and its negative consequences, has been highlighted in various scientific disciplines. Northern domination of science relevant to climate change policy and practice, and limited research led by Southern researchers in Southern countries, may hinder further development and implementation of global climate change agreements and nationally appropriate actions. Despite efforts to address the North-South divide, progress has been slow. In this Perspective, we illustrate the extent of the divide, review underlying issues and analyse their consequences for climate change policy development and implementation. We propose a set of practical steps in both Northern and Southern countries that a wide range of actors should take at global, regional and national scales to span the North-South divide, with examples of some actions already being implemented.
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| 5. |
- Liu, Hong, et al.
(författare)
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On the maximum number of integer colourings with forbidden monochromatic sums
- 2021
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Ingår i: The Electronic Journal of Combinatorics. - : The Electronic Journal of Combinatorics. - 1097-1440 .- 1077-8926. ; 28:1
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Tidskriftsartikel (refereegranskat)abstract
- Let f(n, r) denote the maximum number of colourings of A ⊆ {1, …, n} with r colours such that each colour class is sum-free. Here, a sum is a subset {x, y, z} such that x + y = z. We show that f(n, 2) = 2⌈n/2⌉, and describe the extremal subsets. Further, using linear optimisation, we asymptotically determine the logarithm of f(n, r) for r ≤ 5. Similar results were obtained by Hán and Jiménez in the setting of finite abelian groups.
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| 6. |
- Liu, Hong, et al.
(författare)
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Stability from graph symmetrisation arguments with applications to inducibility
- 2023
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Ingår i: Journal of the London Mathematical Society. - : John Wiley & Sons. - 0024-6107 .- 1469-7750. ; 108:3, s. 1121-1162
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Tidskriftsartikel (refereegranskat)abstract
- We present a sufficient condition for the stability property of extremal graph problems that can be solved via Zykov's symmetrisation. Our criterion is stated in terms of an analytic limit version of the problem. We show that, for example, it applies to the inducibility problem for an arbitrary complete bipartite graph B, which asks for the maximum number of induced copies of B in an n-vertex graph, and to the inducibility problem for K2,1,1,1 and K3,1,1, the only complete partite graphs on at most five vertices for which the problem was previously open.
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| 7. |
- Morphis, Michaella, et al.
(författare)
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Accuracy of patient-specific I-131 dosimetry using hybrid whole-body planar-SPECT/CT I-123 and I-131 imaging
- 2024
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Ingår i: EJNMMI Physics. - 2197-7364. ; 11:1
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study aimed to assess the accuracy of patient-specific absorbed dose calculations for tumours and organs at risk in radiopharmaceutical therapy planning, utilizing hybrid planar-SPECT/CT imaging. Methods: Three Monte Carlo (MC) simulated digital patient phantoms were created, with time-activity data for mIBG labelled to I-123 (LEHR and ME collimators) and I-131 (HE collimator). The study assessed the accuracy of the mean absorbed doses for I-131-mIBG therapy treatment planning. Multiple planar whole-body (WB) images were simulated (between 1 to 72 h post-injection (p.i)). The geometric-mean image of the anterior and posterior WB images was calculated, with scatter and attenuation corrections applied. Time-activity curves were created for regions of interest over the liver and two tumours (diameters: 3.0 cm and 5.0 cm) in the WB images. A corresponding SPECT study was simulated at 24 h p.i and reconstructed using the OS-EM algorithm, incorporating scatter, attenuation, collimator-detector response, septal scatter and penetration corrections. MC voxel-based absorbed dose rate calculations used two image sets, (i) the activity distribution represented by the SPECT images and (ii) the activity distribution from the SPECT images distributed uniformly within the volume of interest. Mean absorbed doses were calculated considering photon and charged particle emissions, and beta emissions only. True absorbed doses were calculated by MC voxel-based dosimetry of the known activity distributions for reference. Results: Considering photon and charged particle emissions, mean absorbed dose accuracies across all three radionuclide-collimator combinations of 3.8 ± 5.5% and 0.1 ± 0.9% (liver), 5.2 ± 10.0% and 4.3 ± 1.7% (3.0 cm tumour) and 15.0 ± 5.8% and 2.6 ± 0.6% (5.0 cm tumour) were obtained for image set (i) and (ii) respectively. Considering charged particle emissions, accuracies of 2.7 ± 4.1% and 5.7 ± 0.7% (liver), 3.2 ± 10.2% and 9.1 ± 1.7% (3.0 cm tumour) and 13.6 ± 5.7% and 7.0 ± 0.6% (5.0 cm tumour) were obtained for image set (i) and (ii) respectively. Conclusion: The hybrid WB planar-SPECT/CT method proved accurate for I-131-mIBG dosimetry, suggesting its potential for personalized treatment planning.
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| 8. |
- Morphis, Michaella, et al.
(författare)
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Evaluation of Iodine-123 and Iodine-131 SPECT activity quantification : a Monte Carlo study
- 2021
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Ingår i: EJNMMI Physics. - : Springer Science and Business Media LLC. - 2197-7364. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: The quantitative accuracy of Nuclear Medicine images, acquired for both planar and SPECT studies, is influenced by the isotope-collimator combination as well as image corrections incorporated in the iterative reconstruction process. These factors can be investigated and optimised using Monte Carlo simulations. This study aimed to evaluate SPECT quantification accuracy for 123I with both the low-energy high resolution (LEHR) and medium-energy (ME) collimators and 131I with the high-energy (HE) collimator. Methods: Simulated SPECT projection images were reconstructed using the OS-EM iterative algorithm, which was optimised for the number of updates, with appropriate corrections for scatter, attenuation and collimator detector response (CDR), including septal scatter and penetration compensation. An appropriate calibration factor (CF) was determined from four different source geometries (activity-filled: water-filled cylindrical phantom, sphere in water-filled (cold) cylindrical phantom, sphere in air and point-like source), investigated with different volume of interest (VOI) diameters. Recovery curves were constructed from recovery coefficients to correct for partial volume effects (PVEs). The quantitative method was evaluated for spheres in voxel-based digital cylindrical and patient phantoms. Results: The optimal number of OS-EM updates was 60 for all isotope-collimator combinations. The CFpoint with a VOI diameter equal to the physical size plus a 3.0-cm margin was selected, for all isotope-collimator geometries. The spheres’ quantification errors in the voxel-based digital cylindrical and patient phantoms were less than 3.2% and 5.4%, respectively, for all isotope-collimator combinations. Conclusion: The study showed that quantification errors of less than 6.0% could be attained, for all isotope-collimator combinations, if corrections for; scatter, attenuation, CDR (including septal scatter and penetration) and PVEs are performed. 123I LEHR and 123I ME quantification accuracies compared well when appropriate corrections for septal scatter and penetration were applied. This can be useful in departments that perform 123I studies and may not have access to ME collimators.
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| 9. |
- Morphis, Michaella, et al.
(författare)
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Modelling of energy-dependent spectral resolution for SPECT Monte Carlo simulations using SIMIND
- 2021
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 7:2
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Tidskriftsartikel (refereegranskat)abstract
- Monte Carlo (MC) modelling techniques have been used extensively in Nuclear Medicine (NM). The theoretical energy resolution relationship (∝1/E−−√), does not accurately predict the gamma camera detector response across all energies. This study aimed to validate the accuracy of an energy resolution model for the SIMIND MC simulation code emulating the Siemens Symbia T16 dual-head gamma camera.MethodsMeasured intrinsic energy resolution data (full width half maximum (FWHM) values), for Ba-133, Lu-177, Am-241, Ga-67, Tc-99m, I-123, I-131 and F-18 sources in air, were used to create a fitted model of the energy response of the gamma camera. Both the fitted and theoretical models were used to simulate intrinsic and extrinsic energy spectra using three different scenarios (source in air; source in simple scatter phantom and a clinical voxel-based digital patient phantom).ResultsThe results showed the theoretical model underestimated the FWHM values at energies above 160.0 keV up to 23.5 keV. In contrast, the fitted model better predicted the measured FWHM values with differences less than 3.3 keV. The I-131 in-scatter energy spectrum simulated with the fitted model better matched the measured energy spectrum. Higher energy photopeaks, (I-123: 528.9 keV and I-131: 636.9 keV) simulated with the fitted model, more accurately resembled the measured photopeaks. The voxel-based digital patient phantom energy spectra, simulated with the fitted and theoretical models, showed the potential impact of an incorrect energy resolution model when simulating isotopes with multiple photopeaks.ConclusionModelling of energy resolution with the proposed fitted model enables the SIMIND user to accurately simulate NM images. A great improvement was seen for high-energy photon emitting isotopes (e.g. I-131), as well as isotopes with multiple photopeaks (e.g. Lu-177, I-131 and Ga-67) in comparison to the theoretical model. This will result in accurate evaluation of radioactivity quantification, which is vital for dosimetric purposes.
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| 10. |
- Morphis, Michaella, et al.
(författare)
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Validation of a SIMIND Monte Carlo modelled gamma camera for Iodine-123 and Iodine-131 imaging
- 2021
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Ingår i: Heliyon. - : Elsevier BV. - 2405-8440. ; 7:6
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: Monte Carlo (MC) modelling techniques can assess the quantitative accuracy of both planar and SPECT Nuclear Medicine images. It is essential to validate the MC code's capabilities in modelling a specific clinical gamma camera, for radionuclides of interest, before its use as a clinical image simulator. This study aimed to determine if the SIMIND MC code accurately simulates emission images measured with a Siemens Symbia™ T16 SPECT/CT system for I-123 with a LEHR and a ME collimator and for I-131 with a HE collimator. Methods: The static and WB planar validation tests included extrinsic system energy pulse-height distributions (EPHDs), system sensitivity and system spatial resolution in air as well as a scatter medium. The SPECT validation test comprised the sensitivity from a simple geometry of a sphere in a cylindrical water-filled phantom. Results: The system EPHDs compared well, with differences between measured and simulated primary photopeak FWHM values not exceeding 4.6 keV. Measured and simulated planar system sensitivity values displayed percentage differences less than 6.9% and 6.3% for static and WB planar images, respectively. Measured and simulated planar system spatial resolution values in air showed percentage differences not exceeding 6.4% (FWHM) and 10.0% (FWTM), and 5.1% (FWHM) and 5.4% (FWTM) for static and WB planar images, respectively. For static planar system spatial resolution measured and simulated in a scatter medium, percentage differences of FWHM and FWTM values were less than 5.8% and 12.6%, respectively. The maximum percentage difference between the measured and simulated SPECT validation results was 3.6%. Conclusion: The measured and simulated validation results compared well for all isotope-collimator combinations and showed that the SIMIND MC code could be used to accurately simulate static and WB planar and SPECT projection images of the Siemens Symbia™ T16 SPECT/CT for both I-123 and I-131 with their respective collimators.
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