| 1. |
- Georgiadou, Elisavet, et al.
(författare)
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Bomb-pulse (14)C analysis combined with (13)C and (15)N measurements in blood serum from residents of Malmö, Sweden.
- 2013
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Ingår i: Radiation and Environmental Biophysics. - : Springer Science and Business Media LLC. - 1432-2099 .- 0301-634X. ; 52:2, s. 175-187
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Forskningsöversikt (refereegranskat)abstract
- The (14)C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of (14)C bomb-pulse dating. The difference between the date estimated using the Calibomb software and sampling date varied between -3 ± 0.4 and +0.2 ± 0.5 years. The average age deviation of all samples was -1.5 ± 0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the (14)C date has been evaluated using stable isotope δ(13)C and δ(15)N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ(13)C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ(13)C and the age deviation. No significant correlation was found between the age deviation and the δ(15)N values of any dietary group. No influence of sex or year of birth was found on neither the (14)C nor the δ(13)C and δ(15)N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ(15)N in the samples. The consumption of high δ(15)N-valued fish and birds can be responsible for this clustering.
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| 2. |
- Georgiadou, Elisavet, et al.
(författare)
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Bomb-pulse 14C analysis combined with 13C and 15N measurements in blood serum from residents of Malmö, Sweden
- 2013
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Konferensbidrag (refereegranskat)abstract
- The 14C content of 60 human blood serum samples from residents of Malmö (Sweden) in 1978, obtained from a biobank, has been measured to estimate the accuracy of 14C bomb-pulse dating. The difference between the date estimated by using the Calibomb software and sampling date varied between -3±0.4 and +0.2±0.5 years. The average age deviation of all samples was -1.5±0.7 years, with the delay between production and consumption of foodstuffs being probably the dominating cause. The potential influence of food habits on the 14C date has been evaluated using stable isotope δ13C and δ15N analysis and information about the dietary habits of the investigated individuals. Although the group consisting of lacto-ovo vegetarians and vegans (pooled group) was not completely separated from the omnivores in a stable isotopic trophic level diagram, this analysis proved to add valuable information on probable dietary habits. The age deviation of the sampling date from the respective Calibomb date was found strongly correlated with the δ13C values, probably due to influence from marine diet components. For the omnivore individuals, there were indications of seasonal effects on δ13C and the age deviation. No significant correlation was found between the age deviation and the δ15N values of any dietary group. No influence of sex or year of birth was found on neither the 14C nor the δ13C and δ15N values of the serum samples. The data were also divided into two groups (omnivores and pooled group), based on the level of δ15N in the samples. The consumption of high δ15N-valued fish and birds can be responsible for this clustering.
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| 3. |
- Georgiadou, Elisavet, et al.
(författare)
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Bomb-pulse dating of human material – modelling the influence of diet
- 2010
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Ingår i: Radiocarbon. - 0033-8222. ; 52:2, s. 800-807
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Konferensbidrag (refereegranskat)abstract
- The atmospheric testing of nuclear weapons during the 1950s and early 1960s produced large amounts of radiocarbon. This 14C bomb pulse provides useful age information in numerous scientific fields, e.g. in geosciences and environmental sciences. Bomb-pulse dating can also be used to date human material (e.g. in forensics and medical science). Bombpulse dating relies on precise measurements of the declining 14C concentration in atmospheric carbon dioxide collected at clean-air sites. However, local variations in the 14C specific activity of air and foodstuffs occur, which are caused by natural processes as well as by various human activities. As 14C enters the human body mainly through the diet, variations of 14C concentration in foodstuffs need to be considered. The marine component of the diet is believed to be of particular importance due to the non-equilibrium in 14C specific activity between the atmosphere and aquatic reservoirs during the bomb pulse. This article reviews the 14C concentration in marine foodstuffs during the bomb-pulse era, and models how the marine component in one’s diet can affect the precision of bomb-pulse dating of human material.
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| 4. |
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| 5. |
- Georgiadou, Elisavet
(författare)
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Exploring the limitations of 14C bomb-pulse dating on human tissue samples
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this work, which will be part of the PhD work of the author of this report, was to evaluate the precision and accuracy expected from bomb-pulse dating of human tissue, focusing on the uncertainties introduced by variation in 14C in the human diet. Such variations may be caused by releases from nuclear installations, hospitals and laboratories using 14C, use of fossil fuels as well as variations in the type of diet consumed (e.g. the percentage of marine food). All this affect the radiocarbon dating of human tissues (Stenström et al. 2010; Georgiadou and Stenström 2010).
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| 6. |
- Georgiadou, Elisavet
(författare)
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Exploring the Possibilities of 14C Bomb-Pulse Dating of Human Tissue Samples
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The testing of nuclear weapons in the atmosphere, in the middle of the 20'h century, resulted in a bomb-pulse excess of atmospheric 14C. A bomb-pulse dating method was thus developed. The latter is a method to determine the time of formation of formerly living modern (i.e. living after 1955) material , based on the 14C/ 12C ratio in it. The objective of this work was to evaluate the factors that can affect the accuracy of bomb-pulse dating of samples originating from the human body. This method may be useful in medicine, for example, to elucidate the progress of an illness. Special importance was given to the effect of diet since the ingestion of food is the main pathway in which carbon enters the human body. Investigation of the diet may reveal the consumption of particular foodstuffs, such as marine ingredients, for example, that may have a different 14C/ 12C ratio from the local atmospheric one. A literature investigation was carried out of the 14C/ 12C ratio in the atmosphere and oceans at different geographical locations showing that ordinary intake of marine foodstuffs can lead to age alteration (atmospheric predicted age - diet predicted age) from -2.4 to 1.4 years. 14C/ 12C measurements were also conducted on blood serum from Swedish subjects and atherosclerotic plaque samples from Swedish and Portuguese patients. It was concluded from the blood serum study that the diet of the subjects studied can influence bomb-pulse dating results due to the marine effect, which leads to a time lag (positive or negative) due to the different 14C/ 12C ratio of marine food compared to terrestrial food. This effect can lead to samples after 1963 (the year of the Limited Test Ban Treaty) appearing to be younger, while samples before 1963 appear to be older. The average age deviation (CAL!Bomb date- sampling date) of the blood serum samples was found to be -1.5 ± 0.7 years. The kind of tissue analysed also plays an important role, since carbon turnover times vary in different tissues and organs. Study of atherosclerotic plaque samples from different plaque regions was performed. On average, cap fragments were the youngest (average age 5.54 ± 2.6 years), core fragments were older (average age 7.79 ± 3.7 years) and interface to media fragments were the oldest (average age 9.74 ± 2.4 years). A comparison between atherosclerotic plaque samples and blood serum samples was also performed, confirming the potential influence of the sort of tissue in bomb-pulse dating. Finally, differences were observed in 14C/12C ratios in the same type of samples (plaque) from subjects with different dietary habits (Portuguese and Swedish diets), reinforcing the concept of dietary influence on bom b-pulse dating. A correction of the bomb-pulse dating, with the aid of o13C values for the blood serum samples of this work, was also attempted. The results appeared to be eligible but confirmed that many factors, except for the diet, are potentially affecting the carbon content of samples from the human body.
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| 7. |
- Georgiadou, Elisavet, et al.
(författare)
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Potential Influence of Diet on Bomb-Pulse Dating of Human Plaque Samples
- 2013
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Ingår i: Radiocarbon. - : Cambridge University Press (CUP). - 0033-8222. ; 55:2-3, s. 874-884
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Tidskriftsartikel (refereegranskat)abstract
- The radiocarbon concentration of different atherosclerotic plaque fragments obtained from 20 patients in Portugal, operated in 2000-2001, has been measured in order to define the year of plaque formation. A difference of 1.8-15 yr was observed, with the mean and median both 9 yr, between the bomb-pulse date estimated with the CALIBomb software and the operation date. Stable isotope (delta C-13 and delta N-15) analysis was also performed and provides insight to the diet of the subjects. The wide range of measured stable isotope values could indicate that the subjects' diet varied, including an abundance of marine foodstuffs. It could also mean a different isotope fractionation process for the different plaque fragments (cap, core, interface to media) and a possible difference in tissues in which the various fragments are formed. Analysis of delta C-13 and delta N-15 values of each patient separately revealed subjects considered more influenced by marine foodstuffs consumption.
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| 8. |
- Goncalves, Isabel, et al.
(författare)
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Direct association between diet and the stability of human atherosclerotic plaque.
- 2015
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Mediterranean diet has been suggested to explain why coronary heart disease mortality is lower in southern than northern Europe. Dietary habits can be revealed by isotope ratio mass spectrometry (IRMS) measurement of carbon (δ(13)C) and nitrogen (δ(15)N) in biological tissues. To study if diet is associated with human plaque stability, atherosclerotic plaques from carotid endarterectomy on 56 patients (21 Portuguese and 35 Swedish) were analysed by IRMS and histology. Plaque components affecting rupture risk were measured. Swedish plaques had more apoptosis, lipids and larger cores, as well as fewer proliferating cells and SMC than the Portuguese, conferring the Swedish a more rupture-prone phenotype. Portuguese plaques contained higher δ(13)C and δ(15)N than the Swedish, indicating that Portuguese plaques were more often derived from marine food. Plaque δ(13)C correlated with SMC and proliferating cells, and inversely with lipids, core size, apoptosis. Plaque δ(15)N correlated with SMC and inversely with lipids, core size and apoptosis. This is the first observational study showing that diet is reflected in plaque components associated with its vulnerability. The Portuguese plaques composition is consistent with an increased marine food intake and those plaques are more stable than those from Swedish patients. Marine-derived food is associated with plaque stability.
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| 9. |
- He, Xinkui, et al.
(författare)
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Spatial and spectral properties of the high-order harmonic emission in argon for seeding applications
- 2009
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 79:6
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Tidskriftsartikel (refereegranskat)abstract
- We characterize and control the harmonic emission in the spectral and spatial domains in order to define in which conditions the harmonic radiation can be a high-quality seed for soft x-ray and x-ray free-electron lasers. The length of the gas cell, where harmonics are generated, was optimized and the energy per pulse was determined in absolute value with a calibrated x-ray photodiode. The beam spatial profile was measured and, in some conditions, a very collimated beam with a half-angle divergence below 1 mrad could be obtained. We also show that increasing the intensity of the fundamental laser field leads to a considerable broadening of the bandwidth of the harmonic radiation, allowing us to cover a large spectral range. This effect is due to fundamental reshaping leading to an efficient phase matching of both short- and long-trajectory contributions.
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| 10. |
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| 11. |
- Stenström, Kristina, et al.
(författare)
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Local variations in C-14 - How is bomb-pulse dating of human tissues and cells affected?
- 2010
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Ingår i: Nuclear Instruments & Methods In Physics Research Section B-Beam Interactions With Materials And Atoms. - : Elsevier BV. - 0168-583X. ; 268:7-8, s. 1299-1302
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Konferensbidrag (refereegranskat)abstract
- Atmospheric nuclear weapons testing in the late 1950s and early 1960s almost doubled the amount of C-14 in the atmosphere. The resulting C-14 "bomb-pulse" has been shown to provide useful age information in e.g. forensic and environmental sciences, biology and the geosciences. The technique is also currently being used for retrospective cell dating in man, in order to provide insight into the rate of formation of new cells in the human body. Bomb-pulse dating relies on precise measurements of the declining C-14 concentration in atmospheric CO2 collected at clean-air sites. However, it is not always recognized that the calculations can be complicated in some cases by significant local variations in the specific activity of C-14 in carbon in the air and foodstuff. This paper presents investigations of local C-14 variations in the vicinities of nuclear installations and laboratories using C-14. Levels of C-14 in workers using this radioisotope are also discussed. (C) 2009 Elsevier B.V. All rights reserved.
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