| 1. |
- Smith, Jennifer A, et al.
(författare)
-
Genome-wide association study identifies 74 loci associated with educational attainment
- 2016
-
Ingår i: Nature (London). - : Springer Science and Business Media LLC. - 1476-4687 .- 0028-0836. ; 533:7604, s. 539-542
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Tidskriftsartikel (refereegranskat)abstract
- Educational attainment is strongly influenced by social and other environmental factors, but genetic factors are estimated to account for at least 20% of the variation across individuals. Here we report the results of a genome-wide association study (GWAS) for educational attainment that extends our earlier discovery sample of 101,069 individuals to 293,723 individuals, and a replication study in an independent sample of 111,349 individuals from the UK Biobank. We identify 74 genome-wide significant loci associated with the number of years of schooling completed. Single-nucleotide polymorphisms associated with educational attainment are disproportionately found in genomic regions regulating gene expression in the fetal brain. Candidate genes are preferentially expressed in neural tissue, especially during the prenatal period, and enriched for biological pathways involved in neural development. Our findings demonstrate that, even for a behavioural phenotype that is mostly environmentally determined, a well-powered GWAS identifies replicable associated genetic variants that suggest biologically relevant pathways. Because educational attainment is measured in large numbers of individuals, it will continue to be useful as a proxy phenotype in efforts to characterize the genetic influences of related phenotypes, including cognition and neuropsychiatric diseases.
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| 2. |
- Lee, James J, et al.
(författare)
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Gene discovery and polygenic prediction from a genome-wide association study of educational attainment in 1.1 million individuals.
- 2018
-
Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 50:8, s. 1112-1121
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Tidskriftsartikel (refereegranskat)abstract
- Here we conducted a large-scale genetic association analysis of educational attainment in a sample of approximately 1.1million individuals and identify 1,271independent genome-wide-significant SNPs. For the SNPs taken together, we found evidence of heterogeneous effects across environments. The SNPs implicate genes involved in brain-development processes and neuron-to-neuron communication. In a separate analysis of the X chromosome, we identify 10independent genome-wide-significant SNPs and estimate a SNP heritability of around 0.3% in both men and women, consistent with partial dosage compensation. A joint (multi-phenotype) analysis of educational attainment and three related cognitive phenotypes generates polygenic scores that explain 11-13% of the variance in educational attainment and 7-10% of the variance in cognitive performance. This prediction accuracy substantially increases the utility of polygenic scores as tools in research.
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| 3. |
- Middeldorp, Christel M., et al.
(författare)
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The Early Growth Genetics (EGG) and EArly Genetics and Lifecourse Epidemiology (EAGLE) consortia : design, results and future prospects
- 2019
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Ingår i: European Journal of Epidemiology. - : Springer Science and Business Media LLC. - 0393-2990 .- 1573-7284. ; 34:3, s. 279-300
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Tidskriftsartikel (refereegranskat)abstract
- The impact of many unfavorable childhood traits or diseases, such as low birth weight and mental disorders, is not limited to childhood and adolescence, as they are also associated with poor outcomes in adulthood, such as cardiovascular disease. Insight into the genetic etiology of childhood and adolescent traits and disorders may therefore provide new perspectives, not only on how to improve wellbeing during childhood, but also how to prevent later adverse outcomes. To achieve the sample sizes required for genetic research, the Early Growth Genetics (EGG) and EArly Genetics and Lifecourse Epidemiology (EAGLE) consortia were established. The majority of the participating cohorts are longitudinal population-based samples, but other cohorts with data on early childhood phenotypes are also involved. Cohorts often have a broad focus and collect(ed) data on various somatic and psychiatric traits as well as environmental factors. Genetic variants have been successfully identified for multiple traits, for example, birth weight, atopic dermatitis, childhood BMI, allergic sensitization, and pubertal growth. Furthermore, the results have shown that genetic factors also partly underlie the association with adult traits. As sample sizes are still increasing, it is expected that future analyses will identify additional variants. This, in combination with the development of innovative statistical methods, will provide detailed insight on the mechanisms underlying the transition from childhood to adult disorders. Both consortia welcome new collaborations. Policies and contact details are available from the corresponding authors of this manuscript and/or the consortium websites.
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| 4. |
- Vogelezang, Suzanne, et al.
(författare)
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Novel loci for childhood body mass index and shared heritability with adult cardiometabolic traits.
- 2020
-
Ingår i: PLoS genetics. - : Public Library of Science (PLoS). - 1553-7404. ; 16:10
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Tidskriftsartikel (refereegranskat)abstract
- The genetic background of childhood body mass index (BMI), and the extent to which the well-known associations of childhood BMI with adult diseases are explained by shared genetic factors, are largely unknown. We performed a genome-wide association study meta-analysis of BMI in 61,111 children aged between 2 and 10 years. Twenty-five independent loci reached genome-wide significance in the combined discovery and replication analyses. Two of these, located near NEDD4L and SLC45A3, have not previously been reported in relation to either childhood or adult BMI. Positive genetic correlations of childhood BMI with birth weight and adult BMI, waist-to-hip ratio, diastolic blood pressure and type 2 diabetes were detected (Rg ranging from 0.11 to 0.76, P-values <0.002). A negative genetic correlation of childhood BMI with age at menarche was observed. Our results suggest that the biological processes underlying childhood BMI largely, but not completely, overlap with those underlying adult BMI. The well-known observational associations of BMI in childhood with cardio-metabolic diseases in adulthood may reflect partial genetic overlap, but in light of previous evidence, it is also likely that they are explained through phenotypic continuity of BMI from childhood into adulthood.
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| 5. |
- Allard, Christina, et al.
(författare)
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Rasbiologiskt språkbruk i statens rättsprocess mot sameby
- 2015
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Ingår i: Dagens Nyheter. - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Statens hantering av forskningsresultat i rättsprocessen med Girjas sameby utgör ett hot mot Sverige som rättsstat och kunskapsnation. Åratal av svensk och internationell forskning underkänns och man använder ett språkbruk som skulle kunna vara hämtat från rasbiologins tid. Nu måste staten ta sitt ansvar och börja agera som en demokratisk rättsstat, skriver 59 forskare.
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| 6. |
- Allard, Christina, et al.
(författare)
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Rasbiologiskt språkbruk i statens rättsprocess mot sameby : DN Debatt 2015-06-11
- 2015
-
Annan publikation (populärvet., debatt m.m.)abstract
- Statens hantering av forskningsresultat i rättsprocessen med Girjas sameby utgör ett hot mot Sverige som rättsstat och kunskapsnation. Åratal av svensk och internationell forskning underkänns och man använder ett språkbruk som skulle kunna vara hämtat från rasbiologins tid. Nu måste staten ta sitt ansvar och börja agera som en demokratisk rättsstat, skriver 59 forskare.
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| 7. |
- Bergman, Lina, 1982, et al.
(författare)
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Study for Improving Maternal Pregnancy And Child ouTcomes (IMPACT): a study protocol for a Swedish prospective multicentre cohort study
- 2020
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Ingår i: BMJ Open. - : BMJ. - 2044-6055 .- 2044-6055. ; 10:9, s. e033851-e033851
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Tidskriftsartikel (refereegranskat)abstract
- Introduction First-trimester pregnancy risk evaluation facilitates individualised antenatal care, as well as application of preventive strategies for pre-eclampsia or birth of a small for gestational age infant. A range of early intervention strategies in pregnancies identified as high risk at the end of the first trimester has been shown to decrease the risk of preterm pre-eclampsia (<37 gestational weeks). The aim of this project is to create the Improving Maternal Pregnancy And Child ouTcomes (IMPACT) database; a nationwide database with individual patient data, including predictors recorded at the end of the first trimester and later pregnancy outcomes, to identify women at high risk of pre-eclampsia. A second aim is to link the IMPACT database to a biobank with first-trimester blood samples. Methods and analysis This is a Swedish prospective multicentre cohort study. Women are included between the 11th and 14th weeks of pregnancy. At inclusion, pre-identified predictors are retrieved by interviews and medical examinations. Blood samples are collected and stored in a biobank. Additional predictors and pregnancy outcomes are retrieved from the Swedish Pregnancy Register. Inclusion in the study began in November 2018 with a targeted sample size of 45 000 pregnancies by end of 2021. Creation of a new risk prediction model will then be developed, validated and implemented. The database and biobank will enable future research on prediction of various pregnancy-related complications. Ethics and dissemination Confidentiality aspects such as data encryption and storage comply with the General Data Protection Regulation and with ethical committee requirements. This study has been granted national ethical approval by the Swedish Ethical Review Authority (Uppsala 2018-231) and national biobank approval at Uppsala Biobank (18237 2 2018 231). Results from the current as well as future studies using information from the IMPACT database will be published in peer-reviewed journals.
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| 8. |
- Cole, Michelle J., et al.
(författare)
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Ten years of external quality assessment (EQA) of Neisseria gonorrhoeae antimicrobial susceptibility testing in Europe elucidate high reliability of data
- 2019
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Ingår i: BMC Infectious Diseases. - : BioMed Central. - 1471-2334. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Confidence in any diagnostic and antimicrobial susceptibility testing data is provided by appropriate and regular quality assurance (QA) procedures. In Europe, the European Gonococcal Antimicrobial Susceptibility Programme (Euro-GASP) has been monitoring the antimicrobial susceptibility in Neisseria gonorrhoeae since 2004. Euro-GASP includes an external quality assessment (EQA) scheme as an essential component for a quality-assured laboratory-based surveillance programme. Participation in the EQA scheme enables any problems with the performed antimicrobial susceptibility testing to be identified and addressed, feeds into the curricula of laboratory training organised by the Euro-GASP network, and assesses the capacity of individual laboratories to detect emerging new, rare and increasing antimicrobial resistance phenotypes. Participant performance in the Euro-GASP EQA scheme over a 10 year period (2007 to 2016, no EQA in 2013) was evaluated.METHODS: Antimicrobial susceptibility category and MIC results from the first 5 years (2007-2011) of the Euro-GASP EQA were compared with the latter 5 years (2012-2016). These time periods were selected to assess the impact of the 2012 European Union case definitions for the reporting of antimicrobial susceptibility.RESULTS: dilutions of the modal MIC, respectively. The most common method used was Etest on GC agar base. There was a shift to using breakpoints published by the European Committee on Antimicrobial Susceptibility Testing (EUCAST) in the latter 5 years, however overall impact on the validity of results was limited, as the percentage categorical agreement and MIC concordance changed very little between the two five-year periods.CONCLUSIONS: The high level of comparability of results in this EQA scheme indicates that high quality data are produced by the Euro-GASP participants and gives confidence in susceptibility and resistance data generated by laboratories performing decentralised testing.
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| 9. |
- Davour, Anna, et al.
(författare)
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Applying image analysis techniques to tomographic images of irradiated nuclear fuel assemblies
- 2016
-
Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 96, s. 223-229
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a set of image analysis techniques used for extraction of information from cross-sectional images of nuclear fuel assemblies, achieved from gamma emission tomography measurements. These techniques are based on template matching, an established method for identifying objects with known properties in images.We demonstrate a rod template matching algorithm for identification and counting of the fuel rods present in the image. This technique may be applicable in nuclear safeguards inspections, because of the potential of verifying the presence of all fuel rods, or potentially discovering any that are missing.We also demonstrate the accurate determination of the position of a fuel assembly, or parts of the assembly, within the imaged area. Accurate knowledge of the assembly position enables detailed modelling of the gamma transport through the fuel, which in turn is needed to make tomographic reconstructions quantifying the activity in each fuel rod with high precision.Using the full gamma energy spectrum, details about the location of different gamma-emitting isotopes within the fuel assembly can be extracted. We also demonstrate the capability to determine the position of supporting parts of the nuclear fuel assembly through their attenuating effect on the gamma rays emitted from the fuel. Altogether this enhances the capabilities of non-destructive nuclear fuel characterization.
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| 10. |
- Hellesen, Carl, 1980-, et al.
(författare)
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Nuclear Spent Fuel Parameter Determination using Multivariate Analysis of Fission Product Gamma Spectra
- 2017
-
Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 110, s. 886-895
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we investigate the application of multivariate data analysis methods to the analysis of gamma spectroscopy measurements of spent nuclear fuel (SNF). Using a simulated irradiation and cooling of nuclear fuel over a wide range of cooling times (CT), total burnup at discharge (BU) and initial enrichments (IE) we investigate the possibilities of using a multivariate data analysis of the gamma ray emission signatures from the fuel to determine these fuel parameters. This is accomplished by training a multivariate analysis method on simulated data and then applying the method to simulated, but perturbed, data.We find that for SNF with CT less than about 20 years, a single gamma spectrum from a high resolution gamma spectrometer, such as a high-purity germanium spectrometer, allows for the determination of the above mentioned fuel parameters.Further, using measured gamma spectra from real SNF from Swedish pressurized light water reactors we were able to confirm the operator declared fuel parameters. In this case, a multivariate analysis trained on simulated data and applied to real data was used.
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| 11. |
- Hellesen, Carl, et al.
(författare)
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Transient Simulation of Gas Bubble in a Medium Sized Lead Cooled Fast Reactor
- 2014
-
Ingår i: Proceedings of the International Conference on Physics of Reactors (PHYSOR 2014).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A common problem for many liquid metal cooled fast reactor designs is the positive void worth of the coolant. In this context, an advantage of lead cooled fast reactors is the high temperature of coolant boiling. In contrast to sodium cooled fast reactors this, in practice, precludes coolant boiling. However, partial voiding of the core could result from e.g. gas bubbles entering the core from below. This would introduce a positive reactivity, if the bubble is large enough. In this paper we model this type of event using a point kinetics code coupled to a heat transport code. The reactivity parameters are obtained from a Monte Carlo code. The 300 MWth reactor design Alfred is used as a test case. We show that in general the reactor design studied is robust in such events, and we conclude that small bubbles a measureable Power oscillation would occur. For very large bubbles there exist a possibility of core damage. The cladding is the most sensitive part.
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| 12. |
- Jacobsson, Staffan, 1970-, et al.
(författare)
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Outcomes of the JNT 1955 Phase I Viability Study of Gamma Emission Tomography for Spent Fuel Verification
- 2017
-
Ingår i: ESARDA Bulletin. - 1977-5296. ; :55, s. 10-28
-
Tidskriftsartikel (refereegranskat)abstract
- The potential for gamma emission tomography (GET) to detect partial defects within a spent nuclear fuel assembly has been assessed within the IAEA Support Program project JNT 1955, phase I, which was completed and reported to the IAEA in October 2016. Two safeguards verification objectives were identified in the project; (1) independent determination of the number of active pins that are present in a measured assembly, in the absence of a priori information about the assembly; and (2) quantitative assessment of pin-by-pin properties, for example the activity of key isotopes or pin attributes such as cooling time and relative burnup, under the assumption that basic fuel parameters (e.g., assembly type and nominal fuel composition) are known. The efficacy of GET to meet these two verification objectives was evaluated across a range of fuel types, burnups and cooling times, while targeting a total interrogation time of less than 60 minutes.The evaluations were founded on a modelling and analysis framework applied to existing and emerging GET instrument designs. Monte Carlo models of different fuel types were used to produce simulated tomographer responses to large populations of "virtual" fuel assemblies. The simulated instrument response data were then processed using a variety of tomographic-reconstruction and image- processing methods, and scoring metrics were defined and used to evaluate the performance of the methods.This paper describes the analysis framework and metrics used to predict tomographer performance. It also presents the design of a "universal" GET (UGET) instrument intended to support the full range of verification scenarios envisioned by the IAEA. Finally, it gives examples of the expected partial-defect detection capabilities for some fuels and diversion scenarios, and it provides a comparison of predicted performance for the notional UGET design and an optimized variant of an existing IAEA instrument.
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| 13. |
- Jacobsson, Susanne, 1974-, et al.
(författare)
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WGS analysis and molecular resistance mechanisms of azithromycin-resistant (MIC >2 mg/L) Neisseria gonorrhoeae isolates in Europe from 2009 to 2014
- 2016
-
Ingår i: Journal of Antimicrobial Chemotherapy. - Oxford, United Kingdom : Oxford University Press. - 0305-7453 .- 1460-2091. ; 71:11, s. 3109-3116
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives: To elucidate the genome-based epidemiology and phylogenomics of azithromycin-resistant (MIC >2 mg/L) Neisseria gonorrhoeae strains collected in 2009-14 in Europe and clarify the azithromycin resistance mechanisms.Methods: Seventy-five azithromycin-resistant (MIC 4 to >256 mg/L) N. gonorrhoeae isolates collected in 17 European countries during 2009-14 were examined using antimicrobial susceptibility testing and WGS.Results: Thirty-six N. gonorrhoeae multi-antigen sequence typing STs and five phylogenomic clades, including 4-22 isolates from several countries per clade, were identified. The azithromycin target mutation A2059G (Escherichia coli numbering) was found in all four alleles of the 23S rRNA gene in all isolates with high-level azithromycin resistance (n = 4; MIC ≥256 mg/L). The C2611T mutation was identified in two to four alleles of the 23S rRNA gene in the remaining 71 isolates. Mutations in mtrR and its promoter were identified in 43 isolates, comprising isolates within the whole azithromycin MIC range. No mutations associated with azithromycin resistance were found in the rplD gene or the rplV gene and none of the macrolide resistance-associated genes [mef(A/E), ere(A), ere(B), erm(A), erm(B), erm(C) and erm(F)] were identified in any isolate.Conclusions: Clonal spread of relatively few N. gonorrhoeae strains accounts for the majority of the azithromycin resistance (MIC >2 mg/L) in Europe. The four isolates with high-level resistance to azithromycin (MIC ≥256 mg/L) were widely separated in the phylogenomic tree and did not belong to any of the main clades. The main azithromycin resistance mechanisms were the A2059G mutation (high-level resistance) and the C2611T mutation (low- and moderate-level resistance) in the 23S rRNA gene.
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| 14. |
- Jacobsson Svärd, Staffan, 1970-, et al.
(författare)
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Tomographic determination of spent fuel assembly pin-wise burnup and cooling time for detection of anomalies
- 2015
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The IAEA has initiated Member States’ Support Program project JNT A 1955 to assess the partial defect detection capabilities of gamma emission tomography (GET) for spent nuclear fuel assembly verification. The GET technique is based on measurements of the gamma-ray flux distribution around a spent fuel assembly using dedicated, tomographic equipment and subsequent reconstruction of the internal source distribution using tomographic algorithms applied on the recorded data. One of the verification objectives identified for the project is the quantitative measurement of pin-by-pin properties, e.g. burnup and/or cooling time, for the detection of anomalies and/or verification of operator-declared data. For this objective, reconstruction algorithms that return quantitative, isotopic pin-by-pin data are applied.Previously, GET measurements performed on commercial nuclear fuel assemblies in Sweden have proven capable of determining the relative pin-by-pin power distribution with high precision in BWR fuel with short cooling time, based on the measured distribution of the gamma-ray emitting fission product 140Ba/La in the fuel. In the current project, the capabilities of GET to determine additional pin-wise fuel parameters in additional fuel types are being assessed. The evaluations are based on Monte Carlo simulations of the emission of gamma-rays from the fuel and their detection in a tomographic measurement device.This paper describes the algorithms used for reconstructing quantitative pin-wise data and the results that are anticipated with this technique. It is argued that detailed modelling of the gamma-ray attenuation through the highly inhomogeneous mix of strongly-attenuating fuel rods and less-attenuating surrounding water (wet storage) or air (dry storage) is required to yield high precision in the reconstructed data. The burnup distribution assessment would be based on the recording of 662-keV gamma radiation from 137Cs, whereas the assessment of both burnup and cooling time simultaneously requires the GET measurement and pin-wise reconstruction of at least two isotopes, which puts constraints on the measurement equipment used.
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| 15. |
- Smith, Eric L., et al.
(författare)
-
A Viability Study of Gamma Emission Tomography for Spent Fuel Verification : JNT 1955 Phase I Technical Report
- 2016
-
Rapport (refereegranskat)abstract
- The potential for gamma emission tomography (GET) to detect partial defects within a spent nuclear fuel assembly is being assessed through a collaboration of Support Programs to the International Atomic Energy Agency (IAEA). In the first phase of this study, two safeguards verification objectives have been identified. The first is the independent determination of the number of active pins that are present in the assembly, in the absence of a priori information about the assembly. The second objective is to provide quantitative assay of pin-by-pin properties, for example the activity of key isotopes or pin attributes such as cooling time and relative burnup, under the assumption that basic fuel parameters (e.g., assembly type and nominal fuel composition) are known. The efficacy of GET to meet these two verification objectives has been evaluated across a range of fuel types, burnups, and cooling times, and with a target total interrogation time of less than 60 minutes. This evaluation of GET viability for safeguards applications was founded on a modelling and analysis framework applied to existing and emerging GET instrument designs. Monte Carlo models of different fuel types were used to produce simulated tomographer responses to large populations of “virtual” fuel assemblies. Instrument response data were processed using a variety of tomographic-reconstruction and image-processing methods, and scoring metrics specific to each of the verification objectives were used to predict performance. This report describes the analysis framework and metrics used to predict tomographer performance, the design of a “universal” GET (UGET) instrument intended to support the full range of verification scenarios envisioned by the IAEA, and a comparison of predicted performance for the notional UGET design and an optimized variant of an existing IAEA instrument.
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| 16. |
- Wolniewicz, Peter, et al.
(författare)
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Detecting neutron spectrum perturbations due to coolant density changes in a small lead-cooled fast nuclear reactor
- 2013
-
Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 58, s. 102-109
-
Tidskriftsartikel (refereegranskat)abstract
- The lead-cooled fast reactor (LFR) is one of the nuclear reactor technologies proposed by the Generation IV International Forum (GIF). The lead coolant allows for inherent safety properties attractive from a nuclear safety point of view, but issues related to corrosion of structural materials and the possible positive coolant reactivity coefficient must be addressed before LFRs can be commercially viable. As an example, a small crack in e.g. a heat exchanger can generate a more or less homogeneous distribution of bubbles in the coolant (void) which if unnoticed, has the potential to cause criticality issues. This fact motivated an investigation of a methodology to detect such voids.The suggested methodology is based on measurements of the “slow” and “fast” parts of the neutron spectrum because these parts respond in different ways to voiding. For detection, it is tentatively assumed that fission chambers loaded with U-235 and Pu-239, respectively, are deployed. To investigate the methodology according to sensitivity and precision, a number of scenarios have been simulated and analysed using the core simulator Serpent.The results show that the methodology yields a sensitivity of 3% for each per cent unit of void. Assuming typical detection limits of a few per cent this implies the possibility to detect voids down to the order of 1%. From these studies it was also concluded that the positioning of the detectors relative the reactor core is crucial, which may be useful input during the design phase of a reactor in order to achieve an efficient monitoring system.
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| 17. |
- Wolniewicz, Peter, et al.
(författare)
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Feasibility study of detection of coolant void in liquid metal cooled fast reactors using changes in the neutron spectrum
- 2013
-
Ingår i: Nuclear Engineering and Design. - : Elsevier BV. - 0029-5493 .- 1872-759X. ; 265, s. 1255-1265
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Tidskriftsartikel (refereegranskat)abstract
- Formation of coolant void can lead to an increase in reactivity in metal-cooled fast reactors. Accordingly, the ability to detect formation of void and similar phenomena is highly relevant in order to counteract transient behaviour of such a reactor. As this work shows, the energy distribution of the neutron flux in a fast reactor is sensitive to formation of void. For monitoring purposes, this fact suggests the use of fission chambers with different isotopic content and thus different fission threshold energies. In such a way the monitoring system may be tailored in order to fit the purpose to obtain spectral information of the neutron flux.In this work, simulations have been performed using the Monte-Carlo-based code SERPENT on the ELECTRA reactor design, a 0.5 MWth lead-cooled fast reactor (LFR) planned for in Sweden. The simulations show significant changes in the neutron spectrum due to the formation of void located in specific in-core regions as well as due to a homogeneous core-wide distribution of small bubbles. In an attempt to quantify and to put a number on the spectroscopic changes, the number of neutrons in the high energy region (2–5 MeV) are compared to the number of neutrons in the low-energy region (50–500 keV) and the changes caused by the introduction of void are analyzed. The implications of the findings are discussed.
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| 18. |
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| 19. |
- Wolniewicz, Peter, 1978-, et al.
(författare)
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Reactivity changes in lead-cooled fast reactors due to bubbles in the coolant
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The formation of bubbles in the coolant of a Lead-Cooled Fast Reactor (LFR) may originate from a leaking heat-exchanger and is a potential safety hazard. Small bubbles can travel with the coolant without escaping to the cover gas, causing an increasing effective voiding of the coolant in a homogeneous manner. If the small bubbles coalesce into a larger bubble located at a stagnation zone, the reactor core may eventually be exposed to a transient bubble travelling axially through the core with a resulting change in the reactivity of the system. This study is focused on the reactivity changes caused by bubbles of various sizes and for different vertical positions as the bubble rises through the core. Three different sizes of LFR’s; 50 MWth, 300 MWth and 1200 MWth,respectively were user for the study. The 300 MWth reactor design is based on the Advanced LFR European Demonstrator (ALFRED) and the two other reactors are scaled up and scaled down versions of it and these were simulated in order study the sensitivity to void as a function of reactor size. We show that LFR’s may have a positive reactivity response to transient bubbles and that the sensitivity to changes in reactivity is larger the smaller the reactor. For sufficiently large bubbles all reactors may reach prompt criticality.
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| 20. |
- Adams, Robin, et al.
(författare)
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What is the word for 'Engineering' in Swedish : Swedish students conceptions of their discipline
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Engineering education in Sweden – as in the rest of the world – is experiencing a decline in student interest. There are concerns about the ways in which students think about engineering education, why they join an academic programme in engineering, and why they persist in their studies. In this context the aims of the Nationellt ämnesdidaktiskt Centrum för Teknikutbildning i Studenternas Sammanhang project (CeTUSS) is to investigate the student experience and to identify and support a continuing network of interested researchers, as well as in building capacity for disciplinary pedagogic investigation. The Stepping Stones project brings together these interests in a multi-researcher, multi-institutional study that investigates how tudents and academic staff perceive engineering in Sweden and in Swedish education. The first results of that project are reported here. As this study is situated uniquely in Swedish education, it allows for exploration of “a Swedish perspective” on conceptions of engineering. The Stepping Stones project was based on a model of research capacity-building previously instantiated in the USA and Australia (Fincher & Tenenberg, 2006).
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| 21. |
- Adler, Mats, et al.
(författare)
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Psykiatrisk diagnostik är svårt.
- 2015
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Ingår i: Tidskriften för Svensk Psykiatri. - 1653-8579. ; 2015:4, s. 36-37
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 22. |
- Ahlbäck, Tor
(författare)
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Digitala skrivtavlor - till vad, hur och varför? : En studie om den digitala skrivtavlans betydelse för grundskolans digitalisering utifrån ett lärarperspektiv
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The purpose of this thesis is to examine in what aspects the interactive whiteboard (IWB) has contributed to the digitalization of our schools, and how it may have changed the actual teaching in the classroom. This research explores this question from a didactic perspective, as well as from the perspective of the teachers’ reflections. The main research questions are: What do teachers use the IWB for? How do teachers use the IWB? Why do teachers use the IWB? These questions have been analyzed within a didactic framework, which is based on the expanded didactic triangle (Hudson & Meyer 2011) and the logic of events (von Wright 1983). Data was collected by interviews and surveys. The analysis was done abductively, based on a mixed methods approach. The results show that the IWB has the function of a digital hub in whole-class teaching, being mainly used as a computer projector, film projector and digital whiteboard. The main value of the IWB according to the study is that it provides the teacher access to digital information during a class. In their response, teachers express a wish to vary and adapt the teaching to include the IWB, in order to increase student motivation and participation. The study shows major differences with regards to the extent and the ways that the IWB is used in relation to teacher and school, leading to differences in pupils’ learning. Moreover, the complexity of teaching increases with the introduction of the IWB, as it requires the development of the teacher’s knowledge and skills. The study indicates that the use of the IWB implies a shift of the norm in school’s whole-class teaching to become more digital. The results are further discussed through four aspects of education: classroom practice, teachers, the school as an organization and society as a whole. The results imply that in order to develop teachers’ didactic repertoire, teachers need to be given clear assignments as well as opportunities for investigating the possibilities and limitations of digital tools, including developing and describing different methods and their advantages and disadvantages. This is proposed to be an area for further research in general and subject didactics, through action and participatory research.
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| 23. |
- Ahlgren-Moritz, Charlotte, et al.
(författare)
-
Vägen till samverkanssäkrad utbildning. [1] : Metoder och strategier
- 2016
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Universitet och högskolor bidrar till samhällsutvecklingen genom att forskningsbaserad kunskap tillämpas av olika aktörer i samhället. För att möta dagens och morgondagens samhällsutmaningar utgör således kunskapsutbyte och samverkan mellan lärosäten och samhället en värdefull möjlighet. Att ha starka relationer med samhällets aktörer identifieras också som viktigt i utvecklingen av ett internationellt starkt lärosäte.Samverkan i högre utbildning främjar samhällets förändringsförmåga och stärker utbildningens kvalitet, men samverkan förbereder också studenterna för ett livslångt lärande och underlättar övergången mellan utbildning och arbetsliv. Ett lärosäte i nära samverkan med aktörer i samhället är ett relevant lärosäte, det vill säga ett lärosäte som är till nytta för sin omvärld och för sina medarbetare och studenter.Ett grundläggande problem vad gäller möjligheterna att integrera samverkan i akademisk utbildning står att finna i statens fördelning av medel till lärosätena. De statliga medlen utgår nämligen i två separata anslag, ett vardera för de båda huvuduppdragen utbildning och forskning. Samverkan kan sägas ingå i bägge uppdragen. Till skillnad från forskningssamverkan finns det för utbildningssamverkan ingen särskild uppföljning och inte heller några ekonomiska incitament. Utvärdering av forskning och utbildning bör således breddas så att kvalitetsstärkande samverkansinslag också inkluderas i resursfördelningsprinciperna. Statens bristande strukturer för fördelning och uppföljning återspeglas i hur lärosätena fördelar resurser till och följer upp samverkan: lärare ges sällan resurser (i form av särskild tid) för att på ett pedagogiskt genomtänkt sätt kunna inkludera samverkansinslag i undervisningen; samverkan är sällan meriterande eller lönegrundande; och den utbildningssamverkan som bedrivs följs sällan upp – varken på institutions-, fakultets- eller lärosätesnivå. Samma sak kan sägas gälla på nationell nivå – det samverkande lärosätet erhåller inga extra anslag och det bestraffas ej heller för försummelse av detsamma. Att göra samverkan till en integrerad del av utbildningen innebär att samverkan bör ingå i de pedagogiska modeller som lärare använder för att leda studenternas kunskapsutveckling mot de mål som finns angivna i kurs- och utbildningsplaner. Det betyder också att arbetet med samverkan bör inkluderas i processer för styrning, planering och uppföljning av utbildning och undervisning på såväl kurs- och programnivå som på institutions-, fakultets- och lärosätesnivå. Att göra samverkan till en integrerad del av utbildningen är att sträva mot att externa aktörer ska bli en självklar del i den dagliga verksamheten – för studenter såväl som för medarbetare och för de organisationer man samverkar med. För att svenska lärosäten ska ges en realistisk möjlighet att göra samverkan till en integrerad del av utbildningsverksamheten krävs det framför allt följande:att politiker och departement utformar ett fördelningssystem där framgångsrika samverkansinsatser inom utbildningen leder till en förstärkning av resursbasen på lärosätena;att lärosätesledningar tar tydlig ställning för samverkansfrågan i sina strategiska styrdokument och att samverkan införs i lärosätenas kvalitetssäkringssystem för utbildning, samt att lärosätena inför system för att styra och följa upp samverkan i utbildningen på lärosätesövergripande nivå;att ledningen för fakulteter, institutioner eller motsvarande omsätter lärosätets strategiska åtaganden i handlingsplaner och lokala styrdokument samt utformar system för dokumentation, styrning och uppföljning av samverkan i utbildningsprogram;att lärare samt kurs- och programansvariga inför samverkan i utbildningens styrande dokument (t.ex. kurs- och utbildningsplaner) samt i den ordinarie undervisningsverksamheten.Dessutom bör lärosätena – både gemensamt men också vart och ett för sig – införa system och karriärvägar där medarbetares insatser i det vardagliga samverkansarbetet uppmärksammas och belönas.Mot bakgrund av detta kan man konstatera att det är angeläget att lärosätenas strategiska arbete avseende utveckling och uppföljning av samverkan i utbildningen vidareutvecklas. Men, med vilka verktyg, var i verksamheten och på vilka sätt?I följande skrift samlas erfarenheter och goda exempel gjorda inom ramen för ett flerårigt lärosätesövergripande samarbetsprojekt, Samverkanssäkrade utbildningsprogram, där utgångspunkten har varit att identifiera strategier och metoder för att integrera samverkan i utbildningsprogram. Målet har varit att undersöka och beskriva hur samverkan kan vara ett medel som bidrar till att stärka utbildningens kvalitet och relevans, samt ge förslag på hur vägen till samverkanssäkrad utbildning kan se ut.Den centrala slutsatsen är att samverkan, när den är en integrerad del av utbildningen, bidrar till kvalitet och säkerställer att utbildningen blir till nytta för samhället. Det finns också andra vinster med att bedriva ett systematiskt samverkansarbete, till exempel att det leder till pedagogisk utveckling för undervisande personal, att det ökar förutsättningarna för ett utmaningsbaserat lärande med studenten i centrum, att det underlättar övergången från studier till arbetsliv, och att det möjliggör fördjupade relationer med den värld lärosätet finns i. Resan mot samverkanssäkrad utbildning är, med andra ord, mödan väl värd.
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| 24. |
- Ahlgren-Moritz, Charlotte, et al.
(författare)
-
Vägen till samverkanssäkrad utbildning. [2] : Möjligheter och utmaningar
- 2016
-
Bok (övrigt vetenskapligt/konstnärligt)abstract
- Universitet och högskolor bidrar till samhällsutvecklingen genom att forskningsbaserad kunskap tillämpas av olika aktörer i samhället. För att möta dagens och morgondagens samhällsutmaningar utgör således kunskapsutbyte och samverkan mellan lärosäten och samhället en värdefull möjlighet. Att ha starka relationer med samhällets aktörer identifieras också som viktigt i utvecklingen av ett internationellt starkt lärosäte.Samverkan i högre utbildning främjar samhällets förändringsförmåga och stärker utbildningens kvalitet, men samverkan förbereder också studenterna för ett livslångt lärande och underlättar övergången mellan utbildning och arbetsliv. Ett lärosäte i nära samverkan med aktörer i samhället är ett relevant lärosäte, det vill säga ett lärosäte som är till nytta för sin omvärld och för sina medarbetare och studenter.Ett grundläggande problem vad gäller möjligheterna att integrera samverkan i akademisk utbildning står att finna i statens fördelning av medel till lärosätena. De statliga medlen utgår nämligen i två separata anslag, ett vardera för de båda huvuduppdragen utbildning och forskning. Samverkan kan sägas ingå i bägge uppdragen. Till skillnad från forskningssamverkan finns det för utbildningssamverkan ingen särskild uppföljning och inte heller några ekonomiska incitament. Utvärdering av forskning och utbildning bör således breddas så att kvalitetsstärkande samverkansinslag också inkluderas i resursfördelningsprinciperna. Statens bristande strukturer för fördelning och uppföljning återspeglas i hur lärosätena fördelar resurser till och följer upp samverkan: lärare ges sällan resurser (i form av särskild tid) för att på ett pedagogiskt genomtänkt sätt kunna inkludera samverkansinslag i undervisningen; samverkan är sällan meriterande eller lönegrundande; och den utbildningssamverkan som bedrivs följs sällan upp – varken på institutions-, fakultets- eller lärosätesnivå. Samma sak kan sägas gälla på nationell nivå – det samverkande lärosätet erhåller inga extra anslag och det bestraffas ej heller för försummelse av detsamma. Att göra samverkan till en integrerad del av utbildningen innebär att samverkan bör ingå i de pedagogiska modeller som lärare använder för att leda studenternas kunskapsutveckling mot de mål som finns angivna i kurs- och utbildningsplaner. Det betyder också att arbetet med samverkan bör inkluderas i processer för styrning, planering och uppföljning av utbildning och undervisning på såväl kurs- och programnivå som på institutions-, fakultets- och lärosätesnivå. Att göra samverkan till en integrerad del av utbildningen är att sträva mot att externa aktörer ska bli en självklar del i den dagliga verksamheten – för studenter såväl som för medarbetare och för de organisationer man samverkar med. För att svenska lärosäten ska ges en realistisk möjlighet att göra samverkan till en integrerad del av utbildningsverksamheten krävs det framför allt följande:att politiker och departement utformar ett fördelningssystem där framgångsrika samverkansinsatser inom utbildningen leder till en förstärkning av resursbasen på lärosätena;att lärosätesledningar tar tydlig ställning för samverkansfrågan i sina strategiska styrdokument och att samverkan införs i lärosätenas kvalitetssäkringssystem för utbildning, samt att lärosätena inför system för att styra och följa upp samverkan i utbildningen på lärosätesövergripande nivå;att ledningen för fakulteter, institutioner eller motsvarande omsätter lärosätets strategiska åtaganden i handlingsplaner och lokala styrdokument samt utformar system för dokumentation, styrning och uppföljning av samverkan i utbildningsprogram;att lärare samt kurs- och programansvariga inför samverkan i utbildningens styrande dokument (t.ex. kurs- och utbildningsplaner) samt i den ordinarie undervisningsverksamheten.Dessutom bör lärosätena – både gemensamt men också vart och ett för sig – införa system och karriärvägar där medarbetares insatser i det vardagliga samverkansarbetet uppmärksammas och belönas.Mot bakgrund av detta kan man konstatera att det är angeläget att lärosätenas strategiska arbete avseende utveckling och uppföljning av samverkan i utbildningen vidareutvecklas. Men, med vilka verktyg, var i verksamheten och på vilka sätt?I följande skrift samlas erfarenheter och goda exempel gjorda inom ramen för ett flerårigt lärosätesövergripande samarbetsprojekt, Samverkanssäkrade utbildningsprogram, där utgångspunkten har varit att identifiera strategier och metoder för att integrera samverkan i utbildningsprogram. Målet har varit att undersöka och beskriva hur samverkan kan vara ett medel som bidrar till att stärka utbildningens kvalitet och relevans, samt ge förslag på hur vägen till samverkanssäkrad utbildning kan se ut.Den centrala slutsatsen är att samverkan, när den är en integrerad del av utbildningen, bidrar till kvalitet och säkerställer att utbildningen blir till nytta för samhället. Det finns också andra vinster med att bedriva ett systematiskt samverkansarbete, till exempel att det leder till pedagogisk utveckling för undervisande personal, att det ökar förutsättningarna för ett utmaningsbaserat lärande med studenten i centrum, att det underlättar övergången från studier till arbetsliv, och att det möjliggör fördjupade relationer med den värld lärosätet finns i. Resan mot samverkanssäkrad utbildning är, med andra ord, mödan väl värd.
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| 25. |
- Alm, Anna-Karin, et al.
(författare)
-
Vägen till samverkanssäkrad utbildning
- 2016
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Kunskapsutbyte och samverkan mellan lärosäten och andra aktörer i samhället är viktigt för att vi ska kunna möta morgondagens utmaningar. Man måste arbeta över sektorsgränser, inte bara inom forskning utan också inom utbildning. “Vägen till samverkanssäkrad utbildning: metoder och strategier” handlar om hur samverkan kan integreras i högre utbildning. Slutsatserna baseras på de erfarenheter som gjorts i projektet Samverkanssäkrade utbildningsprogram som letts av lärosätena i Linköping, Malmö och Umeå. Publikationens andra del, “Möjligheter och utmaningar”, berättar ett antal historier ur samverkansvardagen. // Att med andra samhällsaktörer samverka kring utformningen av utbildningsprogram och i undervisningen bidrar till kvalitetsutveckling och säkerställer att utbildningen är till nytta för samhället. Samverkan förbereder också studenterna för ett livslångt lärande och underlättar övergången mellan utbildning och arbetsliv. För att man långsiktigt ska kunna integrera samverkan i utbildningsprogram krävs insatser på flera nivåer. Till exempel måste lärosätesledningar ta tydlig ställning i samverkansfrågan i sina styrdokument, och samverkansaspekten måste vara en självklar del av lärosätets kvalitetssäkringssystem. Det krävs också att ledningen för fakulteter och institutioner utformar system för dokumentation, styrning och uppföljning av samverkan. Vidare bör samverkan ingå i de pedagogiska modeller som lärare använder för att leda studenternas kunskapsutveckling, och lärosätena bör också uppmärksamma och belöna framgångsrikt samverkansarbete. Slutligen bör politiker och departement utforma ett fördelningssystem där framgångsrika samverkansinsatser inom utbildningen leder till en förstärkning av resursbasen på lärosätena.
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| 26. |
- Anchordoqui, Luis A., et al.
(författare)
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The Forward Physics Facility : Sites, experiments, and physics potential
- 2022
-
Ingår i: Physics reports. - : Elsevier. - 0370-1573 .- 1873-6270. ; 968, s. 1-50
-
Tidskriftsartikel (refereegranskat)abstract
- The Forward Physics Facility (FPF) is a proposal to create a cavern with the space and infrastructure to support a suite of far-forward experiments at the Large Hadron Collider during the High Luminosity era. Located along the beam collision axis and shielded from the interaction point by at least 100 m of concrete and rock, the FPF will house experiments that will detect particles outside the acceptance of the existing large LHC experiments and will observe rare and exotic processes in an extremely low-background environment. In this work, we summarize the current status of plans for the FPF, including recent progress in civil engineering in identifying promising sites for the FPF and the experiments currently envisioned to realize the FPF's physics potential. We then review the many Standard Model and new physics topics that will be advanced by the FPF, including searches for long-lived particles, probes of dark matter and dark sectors, high-statistics studies of TeV neutrinos of all three flavors, aspects of perturbative and non-perturbative QCD, and high-energy astroparticle physics.
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| 27. |
|
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| 28. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Correction for dynamic bias error in transmission measurements of void fraction
- 2012
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 83:12, s. 125110-
-
Tidskriftsartikel (refereegranskat)abstract
- Dynamic bias errors occur in transmission measurements, such as X-ray, gamma, or neutron radiography or tomography. This is observed when the properties of the object are not stationary in time and its average properties are assessed. The nonlinear measurement response to changes in transmission within the time scale of the measurement implies a bias, which can be difficult to correct for. A typical example is the tomographic or radiographic mapping of void content in dynamic two-phase flow systems. In this work, the dynamic bias error is described and a method to make a first-order correction is derived. A prerequisite for this method is variance estimates of the system dynamics, which can be obtained using high-speed, time-resolved data acquisition. However, in the absence of such acquisition, a priori knowledge might be used to substitute the time resolved data. Using synthetic data, a void fraction measurement case study has been simulated to demonstrate the performance of the suggested method. The transmission length of the radiation in the object under study and the type of fluctuation of the void fraction have been varied. Significant decreases in the dynamic bias error were achieved to the expense of marginal decreases in precision.
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| 29. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Design and initial 1D radiography tests of the FANTOM mobile fast-neutron radiography and tomography system
- 2014
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 756, s. 82-93
-
Tidskriftsartikel (refereegranskat)abstract
- The FANTOM system is a tabletop sized fast-neutron radiography and tomography system newly developed at the Applied Nuclear Physics Division of Uppsala University. The main purpose of the system is to provide time-averaged steam-and-water distribution measurement capability inside the metallic structures of two-phase test loops for Light Water Reactor thermal-hydraulic studies using a portable fusion neutron generator. The FANTOM system provides a set of 1D neutron transmission data, which may be inserted into tomographic reconstruction algorithms to achieve a 2D mapping of the steam-and-water distribution. In this paper, the selected design of FANTOM is described and motivated. The detector concept is based on plastic scintillator elements, separated for spatial resolution. Analysis of pulse heights on an event-to-event basis is used for energy discrimination. Although the concept allows for close stacking of a large number of detector elements, this demonstrator is equipped with only three elements in the detector and one additional element for monitoring the yield from the neutron generator. The first measured projections on test objects of known configurations are presented. These were collected using a Sodern Genie 16 neutron generator with an isotropic yield of about 1E8 neutrons per second, and allowed for characterization of the instrument’s capabilities. At an energy threshold of 10 MeV, the detector offered a count rate of about 500 cps per detector element. The performance in terms of spatial resolution was validated by fitting a Gaussian Line Spread Function to the experimental data, a procedure that revealed a spatial unsharpness in good agreement with the predicted FWHM of 0.5 mm.
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| 30. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Effects of proton escape on detection efficiency in thin scintillator elements and its consequences for optimization of fast-neutron imaging
- 2011
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 651:1, s. 110-116
-
Tidskriftsartikel (refereegranskat)abstract
- Plastic scintillators are commonly used for neutron detection in the MeV energy range, based on n–p scattering and the subsequent deposition of recoil proton's kinetic energy in the detector material. This detection procedure gives a quasi-rectangular energy deposition distribution for mono-energetic neutrons, extending from zero to the neutron energy. However, if the detector sensitive element (DSE) is small, the energy deposition may be incomplete due to the recoil proton escape.In the application of neutron imaging, here exemplified by fast-neutron tomography, two conflicting requirements have been identified: (1) thin DSEs are required to obtain high spatial resolution and (2) energy discrimination may be required to reduce the influence of neutrons being scattered into the DSEs, which generally occurs at lower energies. However, at small DSE widths, the reduction of energy deposition due to recoil proton escape may cause a significant decrease in detection efficiency when energy discrimination is applied.In this work, energy deposition distributions in small-size DSEs have been simulated for Deuterium–Deuterium (DD; 2.5 MeV) and Deuterium–Tritium (DT; 14.1 MeV) fusion neutrons. The intrinsic efficiency has been analyzed as a function of energy discrimination level for various detector widths. The investigations show that proton recoil escape causes a significant drop in intrinsic detection efficiency for thin DSEs. For DT neutrons, the drop is 10% at a width of 3.2 mm and 50% at a width of 0.6 mm, assuming an energy threshold at half the incident neutron energy. The corresponding widths for a DD detector are 0.17 and 0.03 mm, respectively.Finally, implications of the proton escape effect on the design of a fast-neutron tomography device for void distribution measurements at Uppsala University are presented. It is shown that the selection of DSE width strongly affects the instrument design when optimizing for image unsharpness.
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| 31. |
- Andersson, Peter, 1981-
(författare)
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Fast-Neutron Tomography using a Mobile Neutron Generator for Assessment of Steam-Water Distributions in Two-Phase Flows
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes the measurement technique of fast-neutron tomography for assessing spatial distributions of steam and water in two-phase flows. This so-called void distribution is of importance both for safe operation and for efficient use of the fuel in light water reactors, which compose the majority of the world’s commercial nuclear reactors. The technique is aimed for usage at thermal-hydraulic test loops, where heated two-phase flows are being investigated under reactor-relevant conditions.By deploying portable neutron generators in transmission tomography, the technique becomes applicable to stationary objects, such as thermal-hydraulic test loops. Fast neutrons have the advantage of high transmission through metallic structures while simultaneously being relatively sensitive to the water/void content. However, there are also challenges, such as the relatively low yield of commercially available fast-neutron generators, the tendency of fast neutrons to scatter in the interactions with materials and the relatively low efficiency encountered in fast-neutron detection.The thesis describes the design of a prototype instrument, FANTOM, which has been assembled and demonstrated. The main design parameters have been optimized to achieve maximal signal count rate in the detector elements, while simultaneously reaching an image unsharpness of ≤0.5 mm. Radiographic projections recorded with the assembled instrument are presented, and the performance parameters of FANTOM are deduced.Furthermore, tomographic reconstruction methods for axially symmetric objects, which is relevant for some test loops, have been developed and demonstrated on measured data from three test objects. The attenuation distribution was reconstructed with a radial resolution of 0.5 mm and an RMS error of 0.02 cm-1, based on data recorded using an effective measurement time of 3.5 hours per object. For a thermal-hydraulic test loop, this can give a useful indication of the flow mode, but further development is desired to improve the precision of the measurements.Instrument upgrades are foreseen by introducing a more powerful neutron generator and by adding detector elements, speeding up the data collection by several orders of magnitude and allowing for higher precision data. The requirements and performance of an instrument for assessment of arbitrary non-symmetric test loops is discussed, based on simulations.
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| 32. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Neutron tomography for void distribution measurements
- 2010
-
Ingår i: ENC 2010 Transactions. - 9789295064096 ; , s. 40-45
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Neutron tomography has previously been performed using large, stationary neutron sources such as reactors and spallation sources for applications where the object under study can be transported to the source. This paper accounts for the challenges met when applying neutron tomography using a portable accelerator driven neutron generator, which is required when studying non-transportable objects. In general, portable sources offer significantly lower neutron yields than stationary sources, implying the need for either longer measurement times or highly efficient measurement and/or analysis procedures.The particular application investigated here is the mapping of steam distributions in water (void distribution), which is of high importance for the performance of nuclear fuel assemblies in boiling water reactors (BWR). The void distribution cannot be measured directly in a reactor core, so instead various electrically-heated thermal-hydraulic test loops are used. In these loops, void correlations can be determined in full-size fuel-assembly models, such as FRIGG in Sweden and DESIRE in Holland, but measurements are also performed in smaller, less complicated geometries. Previously, gamma tomography has been used to measure the void distribution in the FRIGG loop. However, improved capabilities to map the void distribution can be expected using neutrons because of their higher sensitivity to water relative to metal structures, as compared to gamma rays. At the same time, neutrons as probe also give rise to some challenges, such as high background from scattering.This paper investigates the possibility to use neutron tomography at axially symmetric objects such as the HWAT test loop in Sweden, where an annular two-phase flow of water/void is confined and heated by a steel cylinder. Monte Carlo simulations of the HWAT geometry and a suggested measurement setup have been carried out, using the particle transport code MCNPX. A reconstruction technique which exploits the symmetries in the test loop has been developed, making it possible to reconstruct the internal void distribution from one single projection. A reconstruction is presented, which is based on simulated data corresponding to a 13-min measurement using a DT source emitting 2∙109 neutrons/s. The reconstruction offers a radial view of the local void fraction in 10 annular sections of HWAT, with uncertainties between 2 and 5 void percent units.
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| 33. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Neutron tomography of axially symmetric objects using 14 MeV neutrons from a portable neutron generator
- 2014
-
Ingår i: Review of Scientific Instruments. - : AIP Publishing. - 0034-6748 .- 1089-7623. ; 85:8, s. 085109-
-
Tidskriftsartikel (refereegranskat)abstract
- In nuclear boiling water reactor cores, the distribution of water and steam (void) is essential for both safety and efficiency reasons. In order to enhance predictive capabilities, void distribution assessment is performed in two-phase test-loops under reactor-relevant conditions. This article proposes the novel technique of fast-neutron tomography using a portable deuterium-tritium neutron generator to determine the void distribution in these loops.Fast neutrons have the advantage of high transmission through the metallic structures and pipes typically concealing a thermal-hydraulic test loop, while still being fairly sensitive to the water/void content. However, commercially available fast-neutron generators also have the disadvantage of a relatively low yield and fast-neutron detection also suffers from relatively low detection efficiency. Fortunately, some loops are axially symmetric, a property which can be exploited to reduce the amount of data needed for tomographic measurement, thus limiting the interrogation time needed.In this article, three axially-symmetric test objects depicting a thermal-hydraulic test loop have been examined; steel pipes with outer diameter 24 mm, thickness 1.5 mm and with three different distributions of the plastic material POM inside the pipes. Data recorded with the FANTOM fast-neutron tomography instrument have been used to perform tomographic reconstructions to assess their radial material distribution. Here, a dedicated tomographic algorithm that exploits the symmetry of these objects has been applied, which is described in the paper.Results are demonstrated in 20 rixel (radial pixel) reconstructions of the interior constitution and 2D visualization of the pipe interior is demonstrated. The local POM attenuation coefficients in the rixels were measured with errors (RMS) of 0.025, 0.020 and 0.022 cm-1, solid POM attenuation coefficient. The accuracy and precision is high enough to provide a useful indication on the flow mode, and a visualization of the radial material distribution can be obtained. A benefit of this system is its potential to be mounted at any axial height of a two-phase test section without requirements for pre-fabricated entrances or windows. This could mean a significant increase in flexibility of the void distribution assessment capability at many existing two-phase test loops.
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| 34. |
- Andersson, Peter, 1981-, et al.
(författare)
-
Neutron Tomography Using Mobile Neutron Generators for Assessment of Void Distributions in Thermal Hydraulic Test Loops
- 2015
-
Konferensbidrag (refereegranskat)abstract
- Detailed knowledge of the lateral distribution of steam (void) and water in a nuclear fuel assembly is of great value for nuclear reactor operators and fuel manufacturers, with consequences for both reactor safety and economy of operation. Therefore, nuclear relevant two-phase flows are being studied at dedicated thermal-hydraulic test loop, using twophase flow systems ranging from simplified geometries such as heated circular pipes to full scale mock-ups of nuclear fuel assemblies. Neutron tomography (NT) has been suggested for assessment of the lateral distribution of steam and water in such test loops, motivated by a good ability of neutrons to penetrate the metallic structures of metal pipes and nuclear fuel rod mock-ups, as compared to e. g. conventional X-rays, while the liquid water simultaneously gives comparatively good contrast. However, these stationary test loops require the measurement setup to be mobile, which is often not the case for NT setups. Here, it is acknowledged that fast neutrons of 14 MeV from mobile neutron generators constitute a viable option for a mobile NT system. We present details of the development of neutron tomography for this purpose at the division of Applied Nuclear Physics at Uppsala University. Our concept contains a portable neutron generator, exploiting the fusion reaction of deuterium and tritium, and a detector with plastic scintillator elements designed to achieve adequate spatial and energy resolution, all mounted in a light-weight frame without collimators or bulky moderation to allow for a mobile instrument that can be moved about the stationary thermal hydraulic test sections. The detector system stores event-to-event pulse-height information to allow for discrimination based on the energy deposition in the scintillator elements. Experimental results from the tomographic assessment of axially symmetric test objects are shown, as well as simulation results from a scaled up version of the instrument for nonsymmetrical objects in quarter fuel-bundle size objects. In conclusion, the application of tomography on inch-wide vertical pipes has been experimentally demonstrated and simulation results indicate that tomography of the void distribution in nonsymmetrical vertical flows in quarter BWR fuel bundles is also feasible.
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| 35. |
- Andersson, Peter, 1981-
(författare)
-
Optimization of Equipment for Tomographic Measurements of Void Distributions using Fast Neutrons
- 2011
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This licentiate thesis describes a novel nondestructive measuring technique for determiningspatial distributions of two-phase water flows. In Boiling Water Reactors, which compose themajority of the world's commercial nuclear reactors, this so called void distribution is of importance for safe operation.The presented measurement technique relies on fast neutron transmission tomography using portable neutron generators. Varying hardware options for such an instrument based on this technique and a prototype instrument, which is under construction, are described. The main design parameters are detailed and motivated from a performance point of view. A Paretomultiple objective optimization of the count rate and image unsharpness is presented. The resulting instrument design comprises an array of plastic scintillators for neutron detection. Such detector elements allow for spectroscopic data acquisition and subsequent reduction of background events at low energy by means of introducing an energy threshold in the analysis.The thesis includes two papers: In paper I, the recoil proton energy deposition distribution resulting from the interaction of the incoming neutrons is investigated for thin plastic scintillator elements. It is shown that the recoil proton losses have a large effect on the pulse height distribution and the intrinsic neutron detection efficiency is calculated for varying energy thresholds.In paper II the performance of the planned FANTOM device is investigated using the particle transport code MCNP5. An axially symmetric phantom void distribution is modeled and there construction is compared with the correct solution. According to the solutions, the phantom model can be reconstructed with 10 equal size ring-shaped picture elements, with a precision of better than 5 void percent units using a deuterium-tritium neutron generator with a yield of 3 · 107 neutrons per second and a measurement time of 13 h. However, it should be noted that commercial neutron generators with a factor of 103 higher yields exist and that the measurement time could decrease to less than a minute if such a neutron generator would beutilized.
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| 36. |
- Asplund, Annika, 1979-, et al.
(författare)
-
One Standardized Differentiation Procedure Robustly Generates Homogenous Hepatocyte Cultures Displaying Metabolic Diversity from a Large Panel of Human Pluripotent Stem Cells
- 2016
-
Ingår i: Stem Cell Reviews and Reports. - : Springer Science and Business Media LLC. - 1550-8943 .- 1558-6804. ; 12:1, s. 90-104
-
Tidskriftsartikel (refereegranskat)abstract
- Human hepatocytes display substantial functional inter-individual variation regarding drug metabolizing functions. In order to investigate if this diversity is mirrored in hepatocytes derived from different human pluripotent stem cell (hPSC) lines, we evaluated 25 hPSC lines originating from 24 different donors for hepatic differentiation and functionality. Homogenous hepatocyte cultures could be derived from all hPSC lines using one standardized differentiation procedure. To the best of our knowledge this is the first report of a standardized hepatic differentiation procedure that is generally applicable across a large panel of hPSC lines without any adaptations to individual lines. Importantly, with regard to functional aspects, such as Cytochrome P450 activities, we observed that hepatocytes derived from different hPSC lines displayed inter-individual variation characteristic for primary hepatocytes obtained from different donors, while these activities were highly reproducible between repeated experiments using the same line. Taken together, these data demonstrate the emerging possibility to compile panels of hPSC-derived hepatocytes of particular phenotypes/genotypes relevant for drug metabolism and toxicity studies. Moreover, these findings are of significance for applications within the regenerative medicine field, since our stringent differentiation procedure allows the derivation of homogenous hepatocyte cultures from multiple donors which is a prerequisite for the realization of future personalized stem cell based therapies.
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| 37. |
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| 38. |
- Bergquist, Magnus, 1960, et al.
(författare)
-
The effects of PACS on radiographer’s work practice
- 2007
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Ingår i: Radiography. - London : W.B. Saunders Co. Ltd.. ; 13:3, s. 235-240
-
Tidskriftsartikel (refereegranskat)abstract
- This paper identifies and analyses the effects of picture archiving and communica- tion systems (PACS) on radiographers’ work practice. It shows that the introduction of PACS did not simply entail the transfer of data and information from the analogue world to the digital world, but it also led to the introduction of new ways of communicating, and new activities and responsibilities on the part of radiography staff. Radiographers are called upon to work increasingly independently, and individual practitioners require higher levels of professional expertise. In all, this paper demonstrates that new technical solutions sometimes lead to sub- stantial changes in responsibilities in work. In this example, the radiographers’ work practice has become more highly scientific and they are enjoying a higher level of prestige.
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| 39. |
- Branger, Erik, 1988-, et al.
(författare)
-
Comparison of prediction models for Cherenkov light emissions from nuclear fuel assemblies
- 2017
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- The Digital Cherenkov Viewing Device (DCVD) is a tool used by nuclear safeguards inspectors to verify irradiated nuclear fuel assemblies in wet storage based on the Cherenkov light produced by the assembly. Verification that no rods have been substituted in the fuel, so-called partial-defect verification, is made by comparing the intensity measured with a DCVD with a predicted intensity, based on operator fuel declaration. The prediction model currently used by inspectors is based on simulations of Cherenkov light production in a BWR 8x8 geometry. This work investigates prediction models based on simulated Cherenkov light production in a BWR 8x8 and a PWR 17x17 assembly, as well as a simplified model based on a single rod in water. Cherenkov light caused by both fission product gamma and beta decays were considered.The simulations reveal that there are systematic differences between the models, most noticeably with respect to the fuel assembly cooling time. Consequently, a prediction model that is based on another fuel assembly configuration than the fuel type being measured, will result in systematic over or underestimation of short-cooled fuel as opposed to long-cooled fuel. While a simplified model may be accurate enough for fuel assemblies with fairly homogeneous cooling times, the prediction models may differ by up to 18 \,\% for more heterogeneous fuel. Accordingly, these investigations indicate that the currently used model may need to be exchanged with a set of more detailed, fuel-type specific models, in order minimize the model dependant systematic deviations.
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| 40. |
- Branger, Erik, 1988-, et al.
(författare)
-
Experimental evaluation of models for predicting Cherenkov light intensities from short-cooled nuclear fuel assemblies
- 2018
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 13
-
Tidskriftsartikel (refereegranskat)abstract
- The Digital Cherenkov Viewing Device (DCVD) is a tool used by nuclear safeguards inspectors to verify irradiated nuclear fuel assemblies in wet storage based on the recording of Cherenkov light produced by the assemblies. One type of verification involves comparing the measured light intensity from an assembly with a predicted intensity, based on assembly declarations. Crucial for such analyses is the performance of the prediction model used, and recently new modelling methods have been introduced to allow for enhanced prediction capabilities by taking the irradiation history into account, and by including the cross-talk radiation from neighbouring assemblies in the predictions.In this work, the performance of three models for Cherenkov-light intensity prediction is evaluated by applying them to a set of short-cooled PWR 17x17 assemblies for which experimental DCVD measurements and operator-declared irradiation data was available; (1) a two-parameter model, based on total burnup and cooling time, previously used by the safeguards inspectors, (2) a newly introduced gamma-spectrum-based model, which incorporates cycle-wise burnup histories, and (3) the latter gamma-spectrum-based model with the addition to account for contributions from neighbouring assemblies.The results show that the two gamma-spectrum-based models provide significantly higher precision for the measured inventory compared to the two-parameter model, lowering the standard deviation between relative measured and predicted intensities from 15.2% to 8.1% respectively 7.8%.The results show some systematic differences between assemblies of different designs (produced by different manufacturers) in spite of their similar PWR 17x17 geometries, and possible ways are discussed to address such differences, which may allow for even higher prediction capabilities. Still, it is concluded that the gamma-spectrum-based models enable confident verification of the fuel assembly inventory at the currently used detection limit for partial defects, being a 30% discrepancy between measured and predicted intensities, while some false detection occurs with the two-parameter model. The results also indicate that the gamma-spectrum-based prediction methods are accurate enough that the 30% discrepancy limit could potentially be lowered.
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| 41. |
- Branger, Erik, 1988-, et al.
(författare)
-
Experimental study of background subtraction in Digital Cherenkov Viewing Device measurements
- 2018
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 13:8
-
Tidskriftsartikel (refereegranskat)abstract
- The Digital Cherenkov Viewing Device (DCVD) is an imaging tool used by authority inspectors for partial defect verification of nuclear fuel assemblies in wet storage, i.e. to verify that part of an assembly has not been diverted. One of the currently adopted verification procedures is based on quantitative measurements of the assembly's Cherenkov light emissions, and comparisons to an expected intensity, calculated based on operator declarations. A background subtraction of the intensity data in the recorded images is necessary for accurate quantitative measurements. The currently used background subtraction is aimed at removing an electronics-induced image-wide offset, but it is argued here that the currently adopted procedure may be insufficient.It is recommended that a standard dark-frame subtraction should be used, to remove systematic pixel-wise background due to the electronics, replacing the currently used offset procedure. Experimental analyses show that a dark-frame subtraction would further enhance the accuracy and reliability of DCVD measurements. Furthermore, should ageing of the CCD chip result in larger systematic pixel-wise deviations over time, a dark-frame subtraction can ensure reliable measurements regardless of the age of the CCD chip. It can also help in eliminating any adverse effects of malfunctioning pixels. In addition to the background from electronic noise, ways to compensate for background from neighbouring fuel assemblies and ambient light are also discussed.
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| 42. |
- Branger, Erik, 1988-, et al.
(författare)
-
Improved Cherenkov Light Prediction Model for Enhanced DCVD Performance
- 2018
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Digital Cherenkov Viewing Device (DCVD) is an instrument used to verify irradiated nuclear fuel assemblies in wet storage based on the fuel’s Cherenkov light emissions. The DCVD is frequently used for partial defect verification, verifying that 50% or more of an assembly has not been diverted. The verification methodology is based on comparison of the measured Cherenkov light intensity to a predicted intensity, based on operator declarations.For the last five years, a dedicated PhD project at Uppsala University has been aiming at enhancing and improving the verification capabilities when using the DCVD. The project is now approaching its end, and this paper summarizes the comprehensive work performed regarding improving the prediction capabilities.A new prediction model has been developed, considering more fuel assembly details to ensure more accurate predictions. With the new model, the irradiation history of an assembly, the assembly design and the contributions from gamma and beta decays are taken into account. The model has also been extended to account for the radiation from neighbouring fuel assemblies, which can enter the assembly being measured and contribute to the measured Cherenkov light. The performance of the prediction model and the neighbour intensity prediction model has been validated against fuel measurements by the IAEA at a PWR facility with short-cooled fuel. The results show that the new model offers an improved prediction capability, allowing the fuel inventory to be verified with no fuel assemblies being identified as outliers requiring additional investigation. A simplified version of the prediction model will be implemented in the next DCVD software version, making it available to IAEA inspectors.This development of the DCVD capabilities are in line with the fourth theme of the IAEA safeguards symposium, “Shaping the future of safeguards implementation”, by resolving challenges related to the DCVD and by extending the capabilities of the instrument.
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| 43. |
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| 44. |
- Branger, Erik, 1988-, et al.
(författare)
-
Investigating the Cherenkov light production due to cross-talk in closely stored nuclear fuel assemblies in wet storage
- 2018
-
Ingår i: ESARDA Bulletin. - : European Commission Joint Research Centre. - 1977-5296. ; :57, s. 66-74
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The Digital Cherenkov Viewing Device (DCVD) is one of the tools available to a safeguards inspector performing verifications of irradiated nuclear fuel assemblies in wet storage. One of the main advantages of safeguards verification using Cherenkov light is that it can be performed without moving the fuel assemblies to an isolated measurement position, allowing for quick measurements. One disadvantage of this procedure is that irradiated nuclear fuel assemblies are often stored close to each other, and consequently gamma radiation from one assembly can enter a neighbouring assembly, and produce Cherenkov light in the neighbour. As a result, the measured Cherenkov light intensity of one assembly will include contributions from its neighbours, which may affect the safeguards conclusions drawn.In this paper, this so-called near-neighbour effect, is investigated and quantified through simulation. The simulations show that for two fuel assemblies with similar properties stored closely, the near-neighbour effect can cause a Cherenkov light intensity increase of up to 3% in a measurement. For one fuel assembly surrounded by identical neighbour assemblies, a total of up to 14% of the measured intensity may emanate from the neighbours. The relative contribution from the near-neighbour effect also depends on the fuel properties; for a long-cooled, low-burnup assembly, with low gamma and Cherenkov light emission, surrounded by short-cooled, high-burnup assemblies with high emission, the measured Cherenkov light intensity may be dominated by the contributions from its neighbours.When the DCVD is used for partial-defect verification, a 50% defect must be confidently detected. Previous studies have shown that a 50% defect will reduce the measured Cherenkov light intensity by 30% or more, and thus a threshold has been defined, where a ≥30% decrease in Cherenkov light indicates a partial defect. However, this work shows that the near-neighbour effect may also influence the measured intensity, calling either for a lowering of this threshold or for the intensity contributions from neighbouring assemblies to be corrected for. In this work, a method is proposed for assessing the near-neighbour effect based on declared fuel parameters, enabling the latter type of corrections.
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| 45. |
- Branger, Erik, 1988-, et al.
(författare)
-
On Cherenkov light production by irradiated nuclear fuel rods
- 2017
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 12
-
Tidskriftsartikel (refereegranskat)abstract
- Safeguards verification of irradiated nuclear fuel assemblies in wet storage is frequently done by measuring the Cherenkov light in the surrounding water produced due to radioactive decays of fission products in the fuel. This paper accounts for the physical processes behind the Cherenkov light production caused by a single fuel rod in wet storage, and simulations are presented that investigate to what extent various properties of the rod affect the Cherenkov light production. The results show that the fuel properties has a noticeable effect on the Cherenkov light production, and thus that the prediction models for Cherenkov light production which are used in the safeguards verifications could potentially be improved by considering these properties.It is concluded that the dominating source of the Cherenkov light is gamma-ray interactions with electrons in the surrounding water. Electrons created from beta decay may also exit the fuel and produce Cherenkov light, and e.g. Y-90 was identified as a possible contributor to significant levels of the measurable Cherenkov light in long-cooled fuel. The results also show that the cylindrical, elongated fuel rod geometry results in a non-isotropic Cherenkov light production, and the light component parallel to the rod's axis exhibits a dependence on gamma-ray energy that differs from the total intensity, which is of importance since the typical safeguards measurement situation observes the vertical light component. It is also concluded that the radial distributions of the radiation sources in a fuel rod will affect the Cherenkov light production.
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| 46. |
- Branger, Erik, 1988-, et al.
(författare)
-
On the inclusion of light transport in prediction tools for Cherenkov light intensity assessment of irradiated nuclear fuel assemblies
- 2019
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 14
-
Tidskriftsartikel (refereegranskat)abstract
- The Digital Cherenkov Viewing Device (DCVD) is a tool used to verify irradiated nuclear fuel assemblies in wet storage by imaging the Cherenkov light produced by the radiation emitted from the assemblies. It is frequently used for partial defect verification, verifying that part of an assembly has not been removed and/or replaced. In one of the verification procedures used, the detected total Cherenkov light intensities from a set of assemblies are compared to predicted intensities, which are calculated using operator declarations for the assemblies.This work presents a new, time-efficient method to simulate DCVD images of fuel assemblies, allowing for estimations of the Cherenkov light production, transport and detection. Qualitatively, good agreement between simulated and measured images is demonstrated. Quantitatively, it is shown that relative intensity predictions based on simulated images are within 0.5% of corresponding predictions based solely on the production of Cherenkov light, neglecting light transport and detection. Consequently, in most cases it is sufficient to use predictions based on produced Cherenkov light, neglecting transport and detection, thus substantially reducing the time needed for simulations.In a verification campaign, assemblies are grouped according to their type, and the relative measured and predicted intensities are compared in a group. By determining transparency factors, describing the fraction of Cherenkov light that is blocked by the top plate of an assembly, it is possible to adjust predictions based on the production of Cherenkov light to take the effect of the top plate into account. This procedure allows assemblies of the same type bit with different top plates to be compared with increased accuracy. The effect of using predictions adjusted with transparency factors were assessed experimentally on a set of Pressurized Water Reactor 17x17 assemblies having five different top plate designs. As a result of the adjustment, the agreement between measured and predicted relative intensities for the whole data set was enhanced, resulting in a reduction of an RMSE from 14.1% to 10.7%. It is expected that further enhancements may be achieved by introducing more detailed top-plate and spacer descriptions.
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| 47. |
- Byström, Per, et al.
(författare)
-
Early prediction of response to first-line chemotherapy by sequential [18F]-2-fluoro-2-deoxy-D-glucose positron emission tomography in patients with advanced colorectal cancer
- 2009
-
Ingår i: Annals of Oncology. - : Elsevier BV. - 0923-7534 .- 1569-8041. ; 20:6, s. 1057-1061
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: To evaluate [(18)F]-2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET), for early evaluation of response to palliative chemotherapy and for prediction of long-term outcome, in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: In a randomized trial, patients with mCRC received irinotecan-based combination chemotherapy. FDG-PET was carried out before treatment and after two cycles in 51 patients at two centers. Visual changes in tumor FDG uptake and changes measured semi-automatically, as standard uptake values (SUVs), were compared with radiological response after four and eight cycles. RESULTS: The mean baseline SUV for all tumor lesions per patient was higher in nonresponders than in responders (mean 7.4 versus 5.6, P = 0.02). There was a strong correlation between metabolic response (changes in SUV) and objective response (r = 0.57, P = 0.00001), with a sensitivity of 77% and a specificity of 76%. There was no significant correlation between metabolic response and time to progression (P = 0.5) or overall survival (P = 0.1). CONCLUSIONS: Although metabolic response assessed by FDG-PET reflects radiological tumor volume changes, the sensitivity and specificity are too low to support the routine use of PET in mCRC. Furthermore, PET failed to reflect long-term outcome and can, thus, not be used as surrogate end point for hard endpoint benefit.
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| 48. |
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| 49. |
- Bäckman, Karin, et al.
(författare)
-
Vårdens alltför svåra val? : kartläggning av prioriteringsarbete och analys av riksdagens principer och riktlinjer för prioriteringar i hälso- och sjukvården
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- PrioriteringsCentrum har på uppdrag av Socialstyrelsen genomfört en kartläggning av på vilket sätt hälso- och sjukvårdens huvudmän och andra centrala aktörer arbetar med prioriteringar och har utvärderat hur detta arbete överensstämmer med intentionerna i riksdagens beslut om prioriteringar. Vi har även analyserat innehållet i och tillämpningen av riksdagens riktlinjer för prioriteringar i hälso- och sjukvården. Det har skett genom en etisk analys och mot bakgrund av ett stort antal intervjuer i landsting och kommuner samt med representanter för statliga myndigheter och yrkesorganisationer och med ledning av vad som framkommit i tidigare uppföljningar. Vi föreslår i rapporten ett anta förändringar och förtydliganden av riktlinjerna.Vi kan konstatera att sättet att arbeta med prioriteringar i landsting och kommuner inte är helt olikt det som gällde när Prioriteringsdelegationen redovisade en motsvarande uppföljning år 2001. Fortfarande finns knappast några öppna beslut om fördelning och prioritering av resurser om man med öppenhet avser att beslutsfattaren medvetet överväger flera alternativ och att grunderna för besluten är kända för dem som önskar ta del av dem.I situationer då tillgängliga resurser inte befinner sig i paritet med önskvärda ambitioner får sjukvårdspersonalen ta det största ansvaret för att besluta om och genomföra ransonering av vården. Förutom på chefsnivå tycks dock sjukvårdpersonal fortfarande i liten utsträckning vara medveten om de etiska principer som enligt riksdagsbeslutet ska styra prioriteringar i vården. Få känner till den etiska plattformen med de tre etiska principerna. Lokala mallar eller styrdokument för prioriteringar är ovanliga. Det saknas nödvändiga förutsättningar för att tillämpa riksdagens prioriteringsbeslut och det finns inte heller några tydliga strategier för hur man vill skapa sådana förutsättningar inom landstingen.Den kommunala vård- och omsorgsverksamheten upplever sig fortfarande i ringa utsträckning berörd av den etiska plattformen och prioriteringsprinciperna. Någon gemensam prioritering mellan huvudmännen sker knappast alls.Medborgarna är i mycket liten utsträckning involverade i prioriteringsarbetet. Den ökade öppenheten gentemot brukare innebär oftast att viss information om prioriteringar sker genom traditionella kanaler som patientorganisationer, pensionärsråd och handikappråd och synpunkter inhämtas via allmänna patientenkäter medan klagomål hanteras genom patientnämnder.Vi har också funnit tydliga skillnader när det gäller hur arbetet med prioriteringar bedrivs idag jämfört med för sex år sedan. Genom Socialstyrelsen och Läkemedelsförmånsnämnden har staten tagit ledningen när det gäller att visa hur prioriteringar kan göras på ett systematiskt och öppet sätt. Detta arbete har resulterat i en tydlig metodutveckling. Idag finns det dessutom flera exempel på konkret utvecklingsarbete och samverkan mellan huvudmän kring det vidare begreppet kunskapsstyrd vård till vilket systematiska prioriteringar är starkt relaterat. Vi kan också notera olika initiativ till vertikala prioriteringar i verksamheten där det framförallt är läkarkåren som engagerat sig; men också enstaka försök med systematiska politiska prioriteringar. Det finns dessutom flera lovande utvecklingsprojekt rörande prioriteringar som initierats av och drivs av sjukvårdspersonal både lokalt och nationellt. Yrkesförbunden är också mer aktiva idag när det gäller att sprida kunskap om prioriteringar....
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| 50. |
- Carlsson, Jan, et al.
(författare)
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Att bedöma kognitiva psykoterapeuters kompetens, hur göra man? : Jämförelse av två skattningsskalor
- 2008
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Ingår i: Sokraten Medlemstidning. ; :1, s. 11-13
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Begreppet kompetens har visat sig vara svårfångat i kognitiv terapi (Kazantizis 2003). Ändå är det något som vi terapeuter försöker utveckla och uppnå. Ett specifikt försök, som författarna till denna artikel har antagit är "den korrekta och skickliga användningen av en empiriskt validerad modell av terapi på ett sådant sätt att de är sannolikt att resultera i en mera klinisk signifikant förändring för patienten" (James, Blackburn, Milne & Reichelt, 2001, förf. översättning). Flera studier tyder på att både erfarenhet, utbildningsnivå och expertskattad kompetens gör skillnad i behandlingsutfall. (DeRubeis, Hollon, Amsterdam mfl., 2005; Frank, Kupfer, Wgner mfl., 1991; Trepka, Rees, Shapiro mfl., 2004).
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