| 21. |
- Badel, Xavier, et al.
(författare)
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Improvement of an X-ray imaging detector based on a scintillating guides screen
- 2002
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - 0168-9002 .- 1872-9576. ; 487:1-2, s. 129-135
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Tidskriftsartikel (refereegranskat)abstract
- An X-ray imaging detector has been developed for dental applications. The principle of this detector is based on application of a silicon charge coupled device covered by a scintillating wave-guide screen. Previous studies of such a detector showed promising results concerning the spatial resolution but low performance in terms of signal to noise ratio (SNR) and sensitivity. Recent results confirm the wave-guiding properties of the matrix and show improvement of the detector in terms of response uniformity, sensitivity and SNR. The present study is focussed on the fabrication of the scintillating screen where the principal idea is to fill a matrix of Si pores with a CsI scintillator. The photoluminescence technique was used to prove the wave-guiding property of the matrix and to inspect the filling uniformity of the pores. The final detector was characterized by X-ray evaluation in terms of spatial resolution, light output and SNR. A sensor with a spatial resolution of 9 LP/mm and a SNR over 50 has been achieved using a standard dental X-ray source and doses in the order of those used at the moment by dentists (around 25 mR).
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| 22. |
- Badel, Xavier, et al.
(författare)
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Metallized and oxidized silicon macropore arrays filled with a scintillator for CCD-based X-ray imaging detectors
- 2004
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Ingår i: IEEE Transactions on Nuclear Science. - : IEEE. - 0018-9499 .- 1558-1578. ; 51:3, s. 1001-1005, s. 1006-1010
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Tidskriftsartikel (refereegranskat)abstract
- Silicon charge-coupled devices (CCDs) covered with a scintillating film are now available on the market for use in digital medical imaging. However, these devices could still be improved in terms of sensitivity and especially spatial resolution by coating the CCD with an array of scintillating waveguides. In this paper, such waveguides were fabricated by first etching pores in silicon, then performing metallization or oxidation of the pore walls and finally filling the pores with CsI(TI). The resulting structures were observed using scanning electron microscopy and tested under X-ray exposure. Theoretical efficiencies of macropore arrays filled with CsI(TI) were also calculated, indicating that the optimal pore depth for metallized macropore arrays is about 80 mum while it is around 350 mum for oxidized ones. This result, together with the roughness of the metal coating, explains why lower SNR values were measured with the metallized macropores. Indeed, the macropore arrays had depths in the range of 210-390 mum, which is favorable to oxidized structures.
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| 23. |
- Badel, Xavier, et al.
(författare)
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Performance of scintillating waveguides for CCD-based X-ray detectors
- 2006
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499 .- 1558-1578. ; 53:1, s. 3-8
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Tidskriftsartikel (refereegranskat)abstract
- Scintillating films are usually used to improve the sensitivity of CCD-based X-ray imaging detectors. For an optimal spatial resolution and detection efficiency, a tradeoff has to be made on the film thickness. However, these scintillating layers can also be structured to provide a pixellated screen. In this paper, the study of CsI(TI)-filled pore arrays is reported. The pores are first etched in silicon, then oxidized and finally filled with CsI(TI) to form scintillating waveguides. The dependence of the detector sensitivity on pore depth, varied from 40 to 400 mu m here, follows rather well theoretical predictions. Most of the detectors produced in this work have a detective quantum efficiency of the incoming X-ray photons of about 25%. However, one detector shows that higher efficiency can be achieved approaching almost the theoretical limit set by Poisson statistics of the incoming X-rays. Thus, we conclude that it is possible to fabricate scintillating waveguides with almost ideal performance. Imaging capabilities of the detectors are demonstrated.
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| 24. |
- Bellman, Lina, et al.
(författare)
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Boende för äldre: En studie av 10 kommuner
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Andelen äldre personer i det svenska samhället ökar. I Sverige finns boendeformer som på olika sätt är anpassade efter äldres behov. Hur utbudet av dessa för äldre individer anpassade boendeformer ser ut och vilken information kommuner ger till äldre kan ses som viktiga för att förstå om äldre väljer att bo kvar eller flytta. I denna rapport kartläggs hur nuvarande utbud av de tre boendeformerna vård- och omsorgsboende, trygghetsbostäder och seniorbostäder ser ut på bostadsmarknaden vad gäller den äldre befolkningen i tio utvalda kommuner. I rapporten ligger tonvikten på kommunala företrädares uppfattningar och på kommunernas planer. För att få en större förståelse görs jämförelser med siffror från samtliga kommuner hämtade från Boverkets Bostadsmarknadsenkät (2014). Denna rapport är den första delen av en större studie som syftar till att undersöka push- och pullfaktorer som påverkar äldres val av boende. Av kartläggningen framgår att bostadsutbudet i de olika kommunerna skiljer sig åt, där vissa har bostadsöverskott medan andra har bostadsunderskott men där majoriteten av kommunerna erbjuder de tre olika boendeformerna. I storstadsregionen och i de större städerna finns ett utbud av samtliga tre boendeformer medan flera av glesbygdskommunerna saknar trygghetsbostäder. Rådgivning i de flesta kommuner är reaktiv snarare än proaktiv. I rapporten väcks frågan om hur vi ska se på boendet för de äldsta.
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| 25. |
- Bellman, Lina, 1971-, et al.
(författare)
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How Does Education from a High-Status University Affect Professional Property Appraisers' Valuation Judgments?
- 2016
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Ingår i: Journal of Real Estate Practice and Education. - : American Real Estate Society. - 1521-4842 .- 1930-8914. ; 19:2, s. 99-124
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Tidskriftsartikel (refereegranskat)abstract
- The repertory grid technique is used to investigate professional property appraisers' thought patterns, and these patterns' complexity, with respect to the universities from which the appraisers graduated. Nearly half of Sweden's 138 authorized property appraisers participated in the study. The results indicate that the appraisers graduating from the university with the longest tradition of property education and ranked highest among the universities offering such education in Sweden have less complex thought patterns than do those graduating from other Swedish universities. This indicates that appraisers graduating from the highest ranked university simplify their valuation judgments more than do other appraisers.
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| 26. |
- Bellman, Lina, et al.
(författare)
-
Valuation standards and methods : are Sweden's (still) different?
- 2019
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Ingår i: Journal of European Real Estate Research. - : Emerald Group Publishing Limited. - 1753-9269 .- 1753-9277. ; 12:1, s. 79-96
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The purpose of this study is to describe and analyse the methods and standards of valuation used by Swedish professional property valuers when appraising commercial properties and factors affecting those standards. The study builds on a 2002 comparative study of valuers in four European countries by McParland et al. (2002), but focuses specifically on property valuers in Sweden. Design/methodology/approach In 2010-2011, a questionnaire was used in face-to-face interviews with about half of the authorised property valuers in Sweden. Another questionnaire was emailed to all authorised property valuers in Sweden 2015 and again about half participated. Findings Analysis of the results shows some new trends in used and preferred standards and methods. Although Swedish valuers still rely mainly on local guidelines, they now increasingly use international standards and company guidelines, which may indicate a growing, if indirect, form of internationalisation. Swedish valuers still use discounted cash flow as their primary method, but their use of comparative methods has increased. Originality/value The data in this comparative study of valuation standards and methods over time used were collected from a specific group of property valuers authorised through the professional Swedish organisation Samhallsbyggarna (Swedish Professionals for the Built Environment), which contributes to an insight in the presiding of the harmonisation of valuation methods and standards.
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| 27. |
- Bengone, Oliver, et al.
(författare)
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Electronic structure and transport properties of CrAs/GaAs/CrAs trilayers from first principles theory
- 2004
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 70:3
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical study of the transport properties of a CrAs/GaAs/CrAs trilayer. The theory was based on a first principles method for calculating the electronic structure, in combination with a Kubo-Landauer approach for calculating the transport properties in a current perpendicular to the plane geometry. We have also investigated the electronic structure and the magnetic properties of this trilayer, with special focus on electronic and magnetic properties at the CrAs/GaAs interface. Finally, we have studied the effects of chemical disorder on the transport properties, in particular the influence of As antisites at both the Cr and Ga sites.
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| 28. |
- Benselfelt, Tobias, et al.
(författare)
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Explaining the Exceptional Wet Integrity of Transparent Cellulose Nanofibril Films in the Presence of Multivalent Ions-Suitable Substrates for Biointerfaces
- 2019
-
Ingår i: Advanced Materials Interfaces. - : WILEY. - 2196-7350. ; 6:13
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanofibrils (CNFs) assemble into water-resilient materials in the presence of multivalent counter-ions. The essential mechanisms behind these assemblies are ion-ion correlation and specific ion effects. A network model shows that the interfibril attraction indirectly influences the wet modulus by a fourth power relationship to the solidity of the network (E-w proportional to phi(4)). Ions that induce both ion-ion correlation and specific ion effects significantly reduce the swelling of the films, and due to the nonlinear relationship dramatically increase the wet modulus. Herein, this network model is used to explain the elastoplastic behavior of wet films of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized, carboxymethylated, and phosphorylated CNFs in the presence of different counter-ions. The main findings are that the aspect ratio of the CNFs influences the ductility of the assemblies, that the bivalency of phosphorylate ligands probably limits the formation of interfibril complexes with divalent ions, and that a higher charge density increases the friction between fibrils by increasing the short-range attraction from ion-ion correlation and specific ion effects. These findings can be used to rationally design CNF materials for a variety of applications where wet strength, ductility, and transparency are important, such as biomaterials or substrates for bioelectronics.
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| 29. |
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| 30. |
- Berg, Miguel
(författare)
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Concept for hybrid random/dynamic radio resource management
- 1998
-
Ingår i: Proceedings of the 1998 9th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, PIMRC '98. Part 3; Boston, MA, USA; 8 Sept. - 11 Sept. 1998. Vol. 1. - New York : IEEE. ; , s. 424-428, s. 424-428
-
Konferensbidrag (refereegranskat)abstract
- Third generation mobile communication systems will allow many different services with varying demands on data rate and delay. For those systems, the fixed radio resource management (RRM) techniques used in today's low rate systems will not be appropriate to ensure efficient utilization of the radio spectrum. Dynamic RRM is necessary in order to cope with the large variations in data rate. We study the bunch concept which is a hybrid between random and dynamic RRM. Within a small synchronized cluster (bunch) we use dynamic radio resource allocation combined with SIR-based power control and between the bunches we use time/frequency hopping to average the interference. We propose an improved RRM algorithm and evaluate the performance of the bunch concept for a Manhattan scenario with mixed traffic. The performance is improved while the computational complexity is reduced compared to our previously published results for the bunch concept. We also show that the performance of a single bunch system is close to the theoretical upper bound.
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