| 1. |
- Bernitt Cartemo, Petty, 1984, et al.
(författare)
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Comparison of computational phantoms and investigation of the effect of biodistribution on activity estimations
- 2016
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Ingår i: Radiation Protection Dosimetry. - : Oxford University Press (OUP). - 0144-8420 .- 1742-3406. ; 171:3, s. 358-364
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Tidskriftsartikel (refereegranskat)abstract
- We have made a comparison between two computational phantoms, modeled from the unified phantom UPh-08T, for whole-body counting applications. One of these was further compared with the ICRP reference adult male computational phantom. The simulations that were performed for the comparison of all three voxel phantoms use various distributions of 60Co. The two voxel phantoms of the UPh-08T showed good agreement, despite different methods of phantom modeling. Also, effects on efficiency of the inhomogeneous distribution of a radionuclide in the computational UPh-08T phantom were studied, using the realistic biodistribution of 140La. Our results show that the activity estimation of radionuclides, which are inhomogeneously distributed in the human body, will be in error if a homogeneous distribution is assumed for the calibration of whole-body counting systems.
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| 2. |
- Cartemo, Petty, et al.
(författare)
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Letter to the Editor.
- 2016
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Ingår i: Radiation protection dosimetry. - : Oxford University Press (OUP). - 1742-3406 .- 0144-8420. ; 168:2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Chernikova, Dina, 1982, et al.
(författare)
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A potential alternative/complement to the traditional thermal neutron based counting in Nuclear Safeguards and Security
- 2016
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 810, s. 164-171
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Tidskriftsartikel (refereegranskat)abstract
- A new concept for thermal neutron based correlation and multiplicity measurements is proposed in this paper. The main idea of the concept consists of using 2.223 MeV gammas (or 1.201 MeV, DE) originating in the (1) H (n,gamma)D-2-reaction instead of using traditional thermal neutron counting. Results of investigations presented in this paper indicate that gammas from thermal neutron capture reactions preserve the information about the correlation characteristics of thermal (fast) neutrons in the same time scale. Therefore, instead of thermal neutron detectors (or as a complement) one may use traditional and inexpensive gamma detectors, such as Nal, BGO, CdZnTe or any other gamma detector. In this work we used D8 x 8 cm(2) Nal scintillator to test the concept. Thus, the new approach helps to address the problem of replacement of He-3-counters and problems related to the specific measurements of spent nuclear fuel directly in the spent fuel pool. It has a particular importance for Nuclear Safeguards and Security. Overall, this work represents the proof of concept study and reports on the experimental and numerical evidence that thermal neutron capture gammas may be used in the context of correlation and multiplicity measurements. Investigations were performed using a (252)-Cf-correlated neutron source and an Am-241-Be-random neutron source. The related idea of the Gamma Differential Die-Away approach is investigated numerically in this paper as well, and will be tested experimentally in future work.
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| 4. |
- Chernikova, Dina, 1982, et al.
(författare)
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Novel passive and active tungsten-based identifiers for maintaining the continuity of knowledge of spent nuclear fuel copper canisters
- 2015
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Ingår i: Annals of Nuclear Energy. - : Elsevier BV. - 0306-4549 .- 1873-2100. ; 75, s. 219-227
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Tidskriftsartikel (refereegranskat)abstract
- A new approach to provide a long-term safeguards identification of spent nuclear fuel containers, in particular copper canisters, is presented in this paper. The approach proposes the use of a tungsten insert marked with a binary code and placed inside the container. The insert is read with a combination of two independent techniques, radiation and ultrasonic measurements, in order to get a unique identification of the cask. Passive and active versions of the tag are considered. The passive version makes use of the radiation coming from the spent nuclear fuel itself. The active version of the tag is based on the use of an artificially introduced mixture of α-emitting isotopes, such as 241Am with materials, 11B and 23Na, which easily undergo α-induced reactions with emission of specific γ-lines, 2313 keV and 1809 keV, respectively. The paper discusses results of the radiation and ultrasonic measurements and Monte-Carlo evaluations as the first proof of the concept. The results of the investigations show the strong potential for this concept to maintain the continuity of knowledge of spent nuclear fuel copper canisters for a time scale up to a few thousands years without compromising the environmental safety of the casks.
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| 5. |
- Chernikova, Dina, 1982, et al.
(författare)
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The neutron-gamma Feynman variance to mean approach: Gamma detection and total neutron-gamma detection (theory and practice)
- 2015
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 782, s. 47-55
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Tidskriftsartikel (refereegranskat)abstract
- Two versions of the neutron gamma variance to mean (Feynman-alpha method or Feynman-Y function) formula for either gamma detection only or total neutron gamma detection, respectively, are derived and compared in this paper. The new formulas have particular importance for detectors of either gamma photons or deleclors sensitive to both neutron and gamma radialion. If applied to a plastic or liquid deleclor, he total neutron-gamma detection Feynman-Y expression corresponds Lo a situation where no discrimination is made between neutrons and gamma parlicles. The gamma variance Lo mean formulas are useful when a detector of only gamma radialion is used or when working with a combined neutron-gamma deleclor at high count rates. The theoretical derivation is based on the Chapman-Kolmogorov equation with the inclusion of general reactions and corresponding intensities for neutrons and gammas, but with the inclusion of prompt reactions only. A one energy group approximation is considered. The comparison of the two different theories is made by using reaction intensities obtained in MCNPX simulations with a simplified geometry for two scintillation detectors and a Cf-252-source. In addition, the variance to mean ratios, neutron, gamma and total neutron-gamma are evaluated experimentally for a weak Cf-252 neutron-gamma source, a Cs-137 random gamma source and a Na-22 correlated gamma source. Due to the focus being on the possibility of using neutron-gamma variance to mean theories for both reactor and safeguards applications, we limited the present study to the general analytical expressions for Feynman-alpha formulas.
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| 6. |
- Eckerström, Marie, 1981, et al.
(författare)
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Longitudinal evaluation of criteria for subjective cognitive decline and preclinical Alzheimer's disease in a memory clinic sample.
- 2017
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Ingår i: Alzheimer's & Dementia. - : Wiley. - 1552-5260 .- 1552-5279. ; 16:8, s. 96-107
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Tidskriftsartikel (refereegranskat)abstract
- Subjective cognitive decline (SCD) and biomarker-based "at-risk" concepts such as "preclinical" Alzheimer's disease (AD) have been developed to predict AD dementia before objective cognitive impairment is detectable. We longitudinally evaluated cognitive outcome when using these classifications.Memory clinic patients (n=235) were classified as SCD (n=122): subtle cognitive decline (n=36) and mild cognitive impairment (n=77) and subsequently subclassified into SCDplus and National Institute on Aging-Alzheimer's Association (NIA-AA) stages 0 to 3. Mean (standard deviation) follow-up time was 48 (35) months. Proportion declining cognitively and prognostic accuracy for cognitive decline was calculated for all classifications.Among SCDplus patients, 43% to 48% declined cognitively. Among NIA-AA stage 1 to 3 patients, 50% to 100% declined cognitively. The highest positive likelihood ratios (+LRs) for subsequent cognitive decline (+LR 6.3), dementia (+LR 3.4), and AD dementia (+LR 6.5) were found for NIA-AA stage2.In a memory clinic setting, NIA-AA stage 2 seems to be the most successful classification in predicting objective cognitive decline, dementia, and AD dementia.
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| 7. |
- Quinlan, Patrick, et al.
(författare)
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Low serum insulin-like growth factor-I (IGF-I) level is associated with increased risk of vascular dementia
- 2017
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Ingår i: Psychoneuroendocrinology. - : Elsevier BV. - 0306-4530. ; 86, s. 169-175
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Tidskriftsartikel (refereegranskat)abstract
- Background Insulin-like growth factor-I (IGF-I) is important for the adult brain, but little is known of the role of IGF-I in Alzheimeŕs disease (AD) or vascular dementia (VaD). Methods A prospective study of 342 patients with subjective or objective mild cognitive impairment recruited at a single memory clinic. We determined whether serum IGF-I concentrations at baseline were associated with the risk of all-cause dementia, AD, or VaD. Patients developing mixed forms of AD and VaD were defined as suffering from VaD. The statistical analyses included Cox proportional hazards regression analysis. Results During the follow-up (mean 3.6 years), 95 (28%) of the patients developed all-cause dementia [AD, n = 37 (11%) and VaD, n = 42 (12%)]. Low as well as high serum IGF-I (quartile 1 or 4 vs. quartiles 2–3) did not associate with all-cause dementia [crude hazard ratio (HR) 1.30, 95% confidence interval (CI): 0.81–2.08 and crude HR 1.05, 95% CI: 0.63–1.75, respectively] or AD (crude HR 0.79, 95% CI: 0.35–1.79 and crude HR 0.94, 95% CI: 0.43–2.06, respectively]. In contrast, low serum IGF-I concentrations were associated with increased risk of VaD (quartile 1 vs. quartiles 2–3, crude HR 2.22, 95% CI: 1.13–4.36). The latter association remained significant also after adjustment for multiple covariates. Conclusions In a memory clinic population, low serum IGF-I was a risk marker for subsequent VaD whereas low IGF-I did not associate with the risk of AD. High serum IGF-I was not related to the risk of conversion to dementia. © 2017 Elsevier Ltd
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| 8. |
- Vesterlund, Anna, 1980, et al.
(författare)
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Characterization of strong 241Am sources
- 2015
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Ingår i: Applied Radiation and Isotopes. - : Elsevier BV. - 0969-8043 .- 1872-9800. ; 99, s. 162-167
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Tidskriftsartikel (refereegranskat)abstract
- Gamma ray spectra of strong 241Am sources may reveal information about the source composition as there may be other radioactive nuclides such as progeny and radioactive impurities present. In this work the possibility to use gamma spectrometry to identify inherent signatures in 241Am sources in order to differentiate sources from each other, is investigated. The studied signatures are age, i.e. time passed since last chemical separation, and presence of impurities. The spectra of some sources show a number of Doppler broadened peaks in the spectrum which indicate the presence of nuclear reactions on light elements within the sources. The results show that the investigated sources can be differentiated between by age and/or presence of impurities. These spectral features would be useful information in a national nuclear forensics library (NNFL) in cases when the visual information on the source, e.g. the source number, is unavailable.
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| 9. |
- Wallin, Anders, 1950, et al.
(författare)
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Alzheimer's disease-subcortical vascular disease spectrum in a hospital-based setting: overview of results from the Gothenburg MCI and dementia studies.
- 2016
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Ingår i: Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism. - : SAGE Publications. - 1559-7016. ; 36:1, s. 95-113
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Forskningsöversikt (refereegranskat)abstract
- The ability to discriminate between Alzheimer's disease (AD), subcortical vascular disease, and other cognitive disorders is crucial for diagnostic purposes and clinical trial outcomes. Patients with primarily subcortical vascular disease are unlikely to benefit from treatments targeting the AD pathogenic mechanisms and vice versa. The Gothenburg mild cognitive impairment (MCI) and dementia studies are prospective, observational, single-center cohort studies suitable for both cross-sectional and longitudinal analysis that outline the cognitive profiles and biomarker characteristics of patients with AD, subcortical vascular disease, and other cognitive disorders. The studies, the first of which started in 1987, comprise inpatients with manifest dementia and patients seeking care for cognitive disorders at an outpatient memory clinic. This article gives an overview of the major published papers (neuropsychological, imaging/physiology, and neurochemical) of the studies including the ongoing Gothenburg MCI study. The main findings suggest that subcortical vascular disease with or without dementia exhibit a characteristic neuropsychological pattern of mental slowness and executive dysfunction and neurochemical deviations typical of white matter changes and disturbed blood-brain barrier function. Our findings may contribute to better healthcare for this underrecognized group of patients. The Gothenburg MCI study has also published papers on multimodal prediction of dementia, and cognitive reserve.Journal of Cerebral Blood Flow & Metabolism advance online publication, 29 July 2015; doi:10.1038/jcbfm.2015.148.
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| 10. |
- Wallin, Anders, 1950, et al.
(författare)
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Cognitive medicine - a new approach in health care science.
- 2018
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Ingår i: BMC psychiatry. - : Springer Science and Business Media LLC. - 1471-244X. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- The challenges of today's society call for more knowledge about how to maintain all aspects of cognitive health, such as speed/attention, memory/learning, visuospatial ability, language, executive capacity and social cognition during the life course.Medical advances have improved treatments of numerous diseases, but the cognitive implications have not been sufficiently addressed. Disability induced by cognitive dysfunction is also a major issue in groups of patients not suffering from Alzheimer's disease or related disorders. Recent studies indicate that several negative lifestyle factors can contribute to the development of cognitive impairment, but intervention and prevention strategies have not been implemented. Disability due to cognitive failure among the workforce has become a major challenge. Globally, the changing aging pyramid results in increased prevalence of cognitive disorders, and the diversity of cultures influences the expression, manifestation and consequences of cognitive dysfunction.Major tasks in the field of cognitive medicine are basic neuroscience research to uncover diverse disease mechanisms, determinations of the prevalence of cognitive dysfunction, health-economical evaluations, and intervention studies. Raising awareness for cognitive medicine as a clinical topic would also highlight the importance of specialized health care units for an integrative approach to the treatment of cognitive dysfunctions.
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