| 11. |
- Persson, Helena, et al.
(författare)
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Charges drive selection of specific antibodies by phage display.
- 2010
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Ingår i: Journal of Immunological Methods. - : Elsevier BV. - 1872-7905 .- 0022-1759. ; 353, s. 24-30
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Tidskriftsartikel (refereegranskat)abstract
- Phage display technology has emerged as a leading approach to select proteins with improved properties for many different types of applications. The selection typically selects not only for improved binding properties but also for other factors such as efficiency of protein production and folding in Escherichia coli, the host in which the proteins and the phage are produced. Furthermore, the selection methodology is likely to influence the character of retrieved variants. We have now defined the extent whereby the charge of the displayed proteins influence the selection process, resulting in an increased average positive charge among selected proteins in comparison to the proteins that are harbored in the library before selection. Implications of and possible routes to minimize this effect are discussed.
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| 12. |
- Persson, Mats, et al.
(författare)
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Energy-resolved CT imaging with a photon-counting silicon-strip detector
- 2014
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Ingår i: Medical Imaging 2014. - : SPIE - International Society for Optical Engineering. - 9780819498267 ; , s. 90333L-
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Konferensbidrag (refereegranskat)abstract
- Photon-counting detectors are promising candidates for use in the next generation of x-ray CT scanners. Among the foreseen benefits are higher spatial resolution, better trade-off between noise and dose, and energy discriminating capabilities. Silicon is an attractive detector material because of its low cost, mature manufacturing process and high hole mobility. However, it is sometimes claimed to be unsuitable for use in computed tomography because of its low absorption efficiency and high fraction of Compton scatter. The purpose of this work is to demonstrate that high-quality energy-resolved CT images can nonetheless be acquired with clinically realistic exposure parameters using a photon-counting silicon-strip detector with eight energy thresholds developed in our group. We use a single detector module, consisting of a linear array of 50 0.5 × 0.4 mm detector elements, to image a phantom in a table-top lab setup. The phantom consists of a plastic cylinder with circular inserts containing water, fat and aqueous solutions of calcium, iodine and gadolinium, in different concentrations. We use basis material decomposition to obtain water, calcium, iodine and gadolinium basis images and demonstrate that these basis images can be used to separate the different materials in the inserts. We also show results showing that the detector has potential for quantitative measurements of substance concentrations.
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| 13. |
- Persson, Mats, et al.
(författare)
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Energy-resolved CT imaging with a photon-counting silicon-strip detector
- 2014
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Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 59:22, s. 6709-6727
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Tidskriftsartikel (refereegranskat)abstract
- Photon-counting detectors are promising candidates for use in the next generation of x-ray computed tomography (CT) scanners. Among the foreseen benefits are higher spatial resolution, better trade-off between noise and dose and energy discriminating capabilities. Silicon is an attractive detector material because of its low cost, mature manufacturing process and high hole mobility. However, it is sometimes overlooked for CT applications because of its low absorption efficiency and high fraction of Compton scatter. The purpose of this work is to demonstrate that silicon is a feasible material for CT detectors by showing energy-resolved CT images acquired with an 80 kVp x-ray tube spectrum using a photon-counting silicon-strip detector with eight energy thresholds developed in our group. We use a single detector module, consisting of a linear array of 50 0.5 x 0.4 mm detector elements, to image a phantom in a table-top lab setup. The phantom consists of a plastic cylinder with circular inserts containing water, fat and aqueous solutions of calcium, iodine and gadolinium, in different concentrations. By using basis material decomposition we obtain water, calcium, iodine and gadolinium basis images and demonstrate that these basis images can be used to separate the different materials in the inserts. We also show results showing that the detector has potential for quantitative measurements of substance concentrations.
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| 14. |
- Persson, Mats, et al.
(författare)
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Quantification of ring artifact visibility in CT
- 2012
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Ingår i: Medical Imaging 2012. - : SPIE - International Society for Optical Engineering. - 9780819489623 ; , s. 83132J-
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Konferensbidrag (refereegranskat)abstract
- Ring artifacts appear in computed tomography images if there are too large inhomogeneities between different detector elements. The question of how large inhomogeneities are acceptable is gaining in importance due to the development of energy discriminating photon counting CT, where detector homogeneity is an important design parameter. We propose using the systematic-to-statistical error quotient q, defined as the variance of the expected log-normalized count number between detector elements (dels) divided by the variance of log-normalized count numbers measured with the same del, as a metric of ring artifact visibility. With a simple observer study using simulated images, it is shown that rings are visible in the reconstructed image if q exceeds a threshold which lies close to 1.2·10 -3 for 1500 detector elements and 2000 projection angles. It is also shown by visual inspection of simulated images that the threshold value is, to a good approximation, inversely proportional to the number of angle measurements and independent of the number of detector elements. The results suggest that a simple oberver study, together with these scaling relationships, is sufficient for establishing sinogram homogeneity requirements for a particular reconstruction method.
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| 15. |
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| 16. |
- Xu, Cheng, et al.
(författare)
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Energy resolution of a segmented silicon strip detector for photon-counting spectral CT
- 2013
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576. ; 715, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- We investigated the energy resolution of a segmented silicon strip detector for photon-counting spectral computed tomography (CT). The detector response to different monochromatic photon energies and various photon fluxes was characterized at the Elettra synchrotron. An RMS energy resolution of 1.50 keV has been demonstrated for 22 keV photons at zero flux, and it deteriorated as a function of input count rate at a rate of 5.1 eV mm(2)/Mcps. The charge sharing effect has been evaluated. The results show that around 11.1% of the interacting photons experience charge sharing for 22 keV photons and 15.3% for 30 keV.
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| 17. |
- Xu, Cheng, et al.
(författare)
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Evaluation of a Second-Generation Ultra-Fast Energy-Resolved ASIC for Photon-Counting Spectral CT
- 2013
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Ingår i: IEEE Transactions on Nuclear Science. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9499 .- 1558-1578. ; 60:1, s. 437-445
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Tidskriftsartikel (refereegranskat)abstract
- A second-generation ultra-fast energy-resolved application specific integrated circuit (ASIC) has been developed for photon-counting spectral computed tomography (CT). The energy resolution, threshold dispersion and gain of the ASIC were characterized with synchrotron radiation at Diamond Light Source. The standard deviation of threshold offsets at zero keV is 0.89 keV. An RMS energy resolution of 1.09 keV has been demonstrated for 15 keV photon energy at a count rate of 40 kcps, and it deteriorates at a rate of 0.29 keV/Mcps with the increase of output cout rate. The count rate performance of the ASIC has also been evaluated with 120 kV polychromatic x-rays produced by a tungsten anode tube and the results are presented.
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| 18. |
- Yveborg, Moa, et al.
(författare)
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Eliminated risk of iodine contrast cancellation with multibin spectral CT
- 2013
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Ingår i: Physics in Medicine and Biology. - : Institute of Physics (IOP). - 0031-9155 .- 1361-6560. ; 58:14, s. N201-N209
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Tidskriftsartikel (refereegranskat)abstract
- This note compares the extent of contrast cancellation induced by iodinated contrast agents in energy integrating and photon counting multibin CT images. The contrast between a hypodense target and soft tissue is modeled for the two systems for a range of iodine concentrations and tube voltages. In energy integrating systems, we show that the contrast vanishes for low concentrations of iodine whereas the same effect is not seen in multibin systems. We conclude that it is the ability of multibin systems to apply weighting schemes post-acquisition that allows the operator to eliminate the risk of contrast cancellation between iodinated targets and the background.
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| 19. |
- Andersen-Hoppe, Annemette, et al.
(författare)
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Deltagarkultur : i teori och praktik
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Texterna i denna digitala antologi är författade av studenterna och lärarna på kursen ”Deltagarkultur”, som är en del av Interreg-projektet Öresundsregionen som kreativ metapol. Texterna är författade av tjänstemän på kulturförvaltningar i Skåne och Danmark, samt av lärare från Malmö högskola. En gemensam nämnare är att de alla ringar in olika både möjligheter och problem med deltagarkultur i praktiken. Vad händer när idealen möter verkligheten? Hur uppfattar deltagarna själva sin roll i de olika kulturella eller pedagogiska projekt de mer eller mindre frivilligt söker sig till eller blir indragna i? Texterna spänner över ett brett spektrum av praktiker, erfarenheter och problemställningar. De använder olika begrepp och angreppsätt för att närma sig alltifrån deltagarstyrda musikfestivaler och konstprojekt till litteraturläsning och projektarbeten på lärarutbildningen. Nya former för kulturstöd som utmanar traditionella bidragssystem undersöks i en av texterna. Läsaren introduceras för fenomen som crowd funding, crowd sourcing, mikrofinansiering och viral spridning. Filosofins hantering av lek och begär konfronteras med kulturpolitiska visioner och policydokument i en annan text. Sist men inte minst ägnar sig texterna åt intensiv självreflexion – vilket inte skall förväxlas med självupptagenhet.
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| 20. |
- Anrup, Roland, et al.
(författare)
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Centrala universitetsvärden hotas av bolagiseringsidén
- 2013
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Ingår i: Dagens nyheter. - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Högskolestiftelser. Förslaget att driva svenska universitet i stiftelseform öppnar för bolagisering. Men det är ingen riktig utredning, utan en politisk pamflett utan eftertanke. Privatisering av universitet hotar både oberoendet, forskningskvaliteten och samhällsnyttan, skriver 36 forskare vid svenska högskolor och universitet.
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