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1.
Schweiz Arch Tierheilkd ; 165(12): 783-791, 2023 Dec.
Article in German | MEDLINE | ID: mdl-38014544

ABSTRACT

INTRODUCTION: After the successful eradication of the bovine viral diarrhea virus (BVDV) in cattle in Austria, the risk of infections with the border disease virus (BDV) remains. Both viruses belong to the pestivirus genus. BDV infections lead to false-positive results in BVDV surveillance. This can be attributed to the contact to small ruminant populations. In particular, keeping cattle together with sheep or goats on a farm or alpine pasture are significant risk factors. Between 2015 and 2022, BDV type 3 was detected in 15 cattles in Austria. These animals were almost exclusively persistently infected calves. However, a positive antibody result for pestiviruses can lead to an extremely time-consuming and costly, and not always successful search for the source of the infection if no active virus excretor is found. This study documents how small ruminants can be integrated into pestivirus monitoring with a manageable amount of work and costs. 23 406 sheep and goat samples from two brucellosis surveillance programs in small ruminants were analyzed retrospectively. Blood samples were examined using pestivirus real-time pool RT-PCR (qPCR). Direct virus detection of BDV-3 was achieved in 40 sheep from five different federal states. Over the entire investigation period a further 37 detections of BDV-3 were found in cattle, sheep and goats outside of this study throughout Austria. This study accounts for 52 % of all border disease detections from 2015 to 2022. By including small ruminants in pestivirus monitoring, the disruptive factor BDV and the risk of its introduction into cattle herds can be significantly minimized in the future.


INTRODUCTION: Après l'éradication réussie du virus de la diarrhée virale bovine (BVDV) chez les bovins en Autriche, le risque d'infections par le virus de la Border Disease (BDV) demeure. Ces deux virus appartiennent au genre des pestivirus. Les infections par le BDV entraînent des résultats faussement positifs dans la surveillance du BVDV. Ce phénomène peut être attribué aux contacts avec les populations de petits ruminants. En particulier, la détention de bovins avec des moutons ou des chèvres sur une exploitation ainsi que les pâturages alpins sont des facteurs de risque importants pour les infections. Entre 2015 et 2022, le BDV de type 3 a été détecté chez 15 bovins en Autriche. Ces animaux étaient presque exclusivement des veaux infectés de manière persistante. Cependant, un résultat positif aux anticorps contre les pestivirus peut conduire à une recherche extrêmement longue et coûteuse et pas toujours fructueuse de la source de l'infection si aucun excréteur de virus actif n'est trouvé. Cette étude montre comment les petits ruminants peuvent être intégrés dans la surveillance des pestivirus avec une quantité de travail et des coûts gérables. À cette fin, 23 460 échantillons d'ovins et de caprins provenant de deux programmes de surveillance de la brucellose chez les petits ruminants ont été utilisés de façon rétrospective. Les échantillons de sang ont été examinés à l'aide de la RT-PCR en temps réel des pestivirus (qPCR). La détection directe du virus BDV-3 a été réalisée chez 40 moutons provenant de cinq länder différents. Sur l'ensemble de la période d'investigation (2015 ­ 2022), 37 autres détections de BDV-3 ont été effectuées chez des bovins, des ovins et des caprins en dehors de cette étude, dans toute l'Autriche. Cette étude représente 52 % de toutes les détections de Border Disease entre 2015 et 2022. En incluant les petits ruminants dans la surveillance des pestivirus, le facteur de perturbation qu'est le BDV et le risque de son introduction dans les troupeaux de bovins peuvent être considérablement minimisés à l'avenir.


Subject(s)
Border disease virus , Goat Diseases , Pestivirus Infections , Pestivirus , Animals , Sheep , Cattle , Pestivirus/genetics , Goats , Austria/epidemiology , Retrospective Studies , Pestivirus Infections/epidemiology , Pestivirus Infections/veterinary , Diarrhea/veterinary , Goat Diseases/epidemiology
2.
Med Probl Perform Art ; 38(1): 16-22, 2023 Mar.
Article in English | MEDLINE | ID: mdl-36854972

ABSTRACT

OBJECTIVE: The feet of professional dancers are exposed to high work-related stresses. To date, data from the professional dance sector concerning this matter are lacking. The aim of this exploratory project was to analyze and evaluate skin health in the foot area with regard to the prevalence of dermatoses, their locations, as well as gender-specific and load-specific differences. METHODS: Professional classical and neo-classical ballet dancers were examined at two time points: in a phase with increased stress (T0: daily training sessions, rehearsals, and high performance frequency) (n=51, 35 females, 16 males) and after a 24-day rest phase (T1: n=35, 28 females, 7 males). In addition, gender-specific and load-specific (T0 and T1) differences were evaluated. RESULTS: All professional dancers were affected by skin lesions of the feet at T0. Hyperkeratosis (96.1%), onychomycosis (27.5%), and subungual hematoma (11.8%) were the most frequent dermatoses of the feet of professional dancers. Onychomycosis affected the nails of the big toes in particular (right 15.7%; left 13.7%), and subungual hematomas were found exclusively on the nails of the first toe (right 7.8%; left 7.8%). Women tended to be more frequently affected by hyperkeratosis, men more frequently by onychomycosis. There were no load-specific differences between the stress and rest phases. CONCLUSION: The prevalence of work-related dermatoses is equally high among female and male dancers. The results can be used for further research and serve as a basis for specific measures of behavioral and environmental prevention in dance.


Subject(s)
Dancing , Onychomycosis , Humans , Female , Male , Pilot Projects , Foot , Lower Extremity
3.
Science ; 372(6543): 742-745, 2021 05 14.
Article in English | MEDLINE | ID: mdl-33986180

ABSTRACT

Half of the chemical elements heavier than iron are produced by the rapid neutron capture process (r-process). The sites and yields of this process are disputed, with candidates including some types of supernovae (SNe) and mergers of neutron stars. We search for two isotopic signatures in a sample of Pacific Ocean crust-iron-60 (60Fe) (half-life, 2.6 million years), which is predominantly produced in massive stars and ejected in supernova explosions, and plutonium-244 (244Pu) (half-life, 80.6 million years), which is produced solely in r-process events. We detect two distinct influxes of 60Fe to Earth in the last 10 million years and accompanying lower quantities of 244Pu. The 244Pu/60Fe influx ratios are similar for both events. The 244Pu influx is lower than expected if SNe dominate r-process nucleosynthesis, which implies some contribution from other sources.

4.
Proc Natl Acad Sci U S A ; 117(36): 21873-21879, 2020 09 08.
Article in English | MEDLINE | ID: mdl-32839339

ABSTRACT

Nuclides synthesized in massive stars are ejected into space via stellar winds and supernova explosions. The solar system (SS) moves through the interstellar medium and collects these nucleosynthesis products. One such product is 60Fe, a radionuclide with a half-life of 2.6 My that is predominantly produced in massive stars and ejected in supernova explosions. Extraterrestrial 60Fe has been found on Earth, suggesting close-by supernova explosions ∼2 to 3 and ∼6 Ma. Here, we report on the detection of a continuous interstellar 60Fe influx on Earth over the past ∼33,000 y. This time period coincides with passage of our SS through such interstellar clouds, which have a significantly larger particle density compared to the local average interstellar medium embedding our SS for the past few million years. The interstellar 60Fe was extracted from five deep-sea sediment samples and accelerator mass spectrometry was used for single-atom counting. The low number of 19 detected atoms indicates a continued but low influx of interstellar 60Fe. The measured 60Fe time profile over the 33 ky, obtained with a time resolution of about ±9 ky, does not seem to reflect any large changes in the interstellar particle density during Earth's passage through local interstellar clouds, which could be expected if the local cloud represented an isolated remnant of the most recent supernova ejecta that traversed the Earth ∼2 to 3 Ma. The identified 60Fe influx may signal a late echo of some million-year-old supernovae with the 60Fe-bearing dust particles still permeating the interstellar medium.

5.
Phys Rev Lett ; 125(3): 031101, 2020 Jul 17.
Article in English | MEDLINE | ID: mdl-32745435

ABSTRACT

For the time period from 1.5 to 4 Myr before the present we found in deep ocean ferromanganese crusts a ^{53}Mn excess concentration in terms of ^{53}Mn/Mn of about 4×10^{-14} over that expected for cosmogenic production. We conclude that this ^{53}Mn is of supernova origin because it is detected in the same time window, about 2.5 Myr ago, where ^{60}Fe has been found earlier. This overabundance confirms the supernova origin of that ^{60}Fe. For the first time, supernova-formed ^{53}Mn has been detected and it is the second positively identified radioisotope from the same supernova. The ratio ^{53}Mn/^{60}Fe of about 14 is consistent with that expected for a SN with a 11-25 M_{⊙} progenitor mass and solar metallicity.

6.
J Environ Radioact ; 205-206: 17-23, 2019 Sep.
Article in English | MEDLINE | ID: mdl-31082674

ABSTRACT

Anthropogenic radionuclides, like 236U and 239,240Pu, are present in the environment as a result of global fallout from nuclear weapons tests conducted in the 1950s and 1960s and can potentially be used as tracers in soil erosion and sediment movement studies. Here, we report data on 236U and 239,240Pu in soil samples from the Motueka Valley (New Zealand) and for the first time from two remote islands Rarotonga and Atiu (Cook Islands) in the South Pacific. 236U and 239,240Pu were measured using Accelerator Mass Spectrometry (AMS) at the Australian National University. The 236U and 239Pu isotope concentrations versus soil depth and the 240Pu/239Pu and 236U/239Pu isotope ratios are discussed for each site. The radionuclide depth dependence revealed any soil disturbance, whereas the isotopic signatures indicated the source of the radionuclides' origin.


Subject(s)
Plutonium/analysis , Radiation Monitoring , Radioactive Fallout/analysis , Soil Pollutants, Radioactive/analysis , Uranium/analysis , Mass Spectrometry , New Zealand , Polynesia
7.
J Environ Radioact ; 178-179: 349-353, 2017 Nov.
Article in English | MEDLINE | ID: mdl-28526526

ABSTRACT

A slice from a Porites Lutea coral core collected inside the Enewetak Atoll lagoon, within 15 km of all major nuclear tests conducted at the atoll, was analysed for 236U, 239Pu and 240Pu over the time interval 1952-1964 using a higher time resolution than previously reported for a parallel slice from the same core. In addition two sediment samples from the Koa and Oak craters were analysed. The strong peaks in the concentrations of 236U and 239Pu in the testing years are confirmed to be considerably wider than the flushing time of the lagoon. This is likely due to the growth mechanism of the coral. Following the last test in 1958 atom concentrations of both 236U and 239Pu decreased from their peak values by more than 95% and showed a seasonal signal thereafter. Between 1959 and 1964 the weighted average of the 240Pu/239Pu atom ratio is 0.124 ± 0.008 which is similar to that in the lagoon sediments (0.129 ± 0.006) but quite distinct from the global fallout value of ∼0.18. This, and the high 239,240Pu and 236U concentrations in the sediments, provides clear evidence that the post-testing signal in the coral is dominated by remobilisation of the isotopes from the lagoon sediments rather than from global fallout.


Subject(s)
Nuclear Weapons , Plutonium/analysis , Radiation Monitoring , Radioactive Fallout/analysis , Uranium/analysis , Water Pollutants, Radioactive/analysis
8.
Nature ; 532(7597): 69-72, 2016 Apr 07.
Article in English | MEDLINE | ID: mdl-27078565

ABSTRACT

The rate of supernovae in our local Galactic neighbourhood within a distance of about 100 parsecs from Earth is estimated to be one every 2-4 million years, based on the total rate in the Milky Way (2.0 ± 0.7 per century). Recent massive-star and supernova activity in Earth's vicinity may be traced by radionuclides with half-lives of up to 100 million years, if trapped in interstellar dust grains that penetrate the Solar System. One such radionuclide is (60)Fe (with a half-life of 2.6 million years), which is ejected in supernova explosions and winds from massive stars. Here we report that the (60)Fe signal observed previously in deep-sea crusts is global, extended in time and of interstellar origin from multiple events. We analysed deep-sea archives from all major oceans for (60)Fe deposition via the accretion of interstellar dust particles. Our results reveal (60)Fe interstellar influxes onto Earth at 1.5-3.2 million years ago and at 6.5-8.7 million years ago. The signal measured implies that a few per cent of fresh (60)Fe was captured in dust and deposited on Earth. Our findings indicate multiple supernova and massive-star events during the last ten million years at distances of up to 100 parsecs.

9.
J Environ Radioact ; 151 Pt 3: 563-7, 2016 Jan.
Article in English | MEDLINE | ID: mdl-26141189

ABSTRACT

The isotopes (236)U, (239)Pu and (240)Pu are present in surface soils as a result of global fallout from nuclear weapons tests carried out in the 1950's and 1960's. These isotopes potentially constitute artificial tracers of recent soil erosion and sediment movement. Only Accelerator Mass Spectrometry has the requisite sensitivity to measure all three isotopes at these environmental levels. Coupled with its relatively high throughput capabilities, this makes it feasible to conduct studies of erosion across the geographical extent of the Australian continent. In the Australian context, however, global fallout is not the only source of these isotopes. As part of its weapons development program the United Kingdom carried out a series of atmospheric and surface nuclear weapons tests at Maralinga, South Australia in 1956 and 1957. The tests have made a significant contribution to the Pu isotopic abundances present in the region around Maralinga and out to distances ∼1000 km, and impact on the assessment techniques used in the soil and sediment tracer studies. Quantification of the relative fallout contribution derived from detonations at Maralinga is complicated owing to significant contamination around the test site from numerous nuclear weapons safety trials that were also carried out around the site. We show that (236)U can provide new information on the component of the fallout that is derived from the local nuclear weapons tests, and highlight the potential of (236)U as a new fallout tracer.


Subject(s)
Plutonium/analysis , Radioactive Fallout/analysis , Soil Pollutants, Radioactive/analysis , Uranium/analysis , Nuclear Weapons , Radiation Monitoring , South Australia
10.
Phys Rev Lett ; 114(4): 041101, 2015 Jan 30.
Article in English | MEDLINE | ID: mdl-25679883

ABSTRACT

In order to resolve a recent discrepancy in the half-life of 60Fe, we performed an independent measurement with a new method that determines the 60Fe content of a material relative to 55Fe (t1/2=2.744 yr) with accelerator mass spectrometry. Our result of (2.50±0.12)×10(6) yr clearly favors the recently reported value (2.62±0.04)×10(6) yr, and rules out the older result of (1.49±0.27)×10(6) yr. The present weighted mean half-life value of (2.60±0.05)×10(6) yr substantially improves the reliability as an important chronometer for astrophysical applications in the million-year time range. This includes its use as a sensitive probe for studying recent chemical evolution of our Galaxy, the formation of the early Solar System, nucleosynthesis processes in massive stars, and as an indicator of a recent nearby supernova.

11.
Nat Commun ; 6: 5956, 2015 Jan 20.
Article in English | MEDLINE | ID: mdl-25601158

ABSTRACT

Half of the heavy elements including all actinides are produced in r-process nucleosynthesis, whose sites and history remain a mystery. If continuously produced, the Interstellar Medium is expected to build-up a quasi-steady state of abundances of short-lived nuclides (with half-lives ≤100 My), including actinides produced in r-process nucleosynthesis. Their existence in today's interstellar medium would serve as a radioactive clock and would establish that their production was recent. In particular (244)Pu, a radioactive actinide nuclide (half-life=81 My), can place strong constraints on recent r-process frequency and production yield. Here we report the detection of live interstellar (244)Pu, archived in Earth's deep-sea floor during the last 25 My, at abundances lower than expected from continuous production in the Galaxy by about 2 orders of magnitude. This large discrepancy may signal a rarity of actinide r-process nucleosynthesis sites, compatible with neutron-star mergers or with a small subset of actinide-producing supernovae.

12.
Phys Rev Lett ; 112(19): 192501, 2014 May 16.
Article in English | MEDLINE | ID: mdl-24877933

ABSTRACT

The neutron capture cross sections of the main uranium isotopes, (235)U and (238)U, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT ∼ 25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of (235)U(n,γ)/(238)U(n,γ) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products (236)U/(239)U, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies.

13.
Nanoscale ; 5(11): 4673-7, 2013 Jun 07.
Article in English | MEDLINE | ID: mdl-23619506

ABSTRACT

Short chains containing a series of metal-molecule-nanoparticle nanojunctions are a nano-material system with the potential to give electrical signatures close to those from single molecule experiments while enabling us to build portable devices on a chip. Inelastic electron tunnelling spectroscopy (IETS) measurements provide one of the most characteristic electrical signals of single and few molecules. In interlinked molecule-nanoparticle (NP) chains containing typically 5-7 molecules in a chain, the spectrum is expected to be a superposition of the vibrational signatures of individual molecules. We have established a stable and reproducible molecule-AuNP multi-junction by placing a few 1,8-octanedithiol (ODT) molecules onto a versatile and portable nanoparticle-nanoelectrode platform and measured for the first time vibrational molecular signatures at complex and coupled few-molecule-NP junctions. From quantum transport calculations, we model the IETS spectra and identify vibrational modes as well as the number of molecules contributing to the electron transport in the measured spectra.

14.
Nucl Instrum Methods Phys Res B ; 294(2-2): 496-502, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23565017

ABSTRACT

Nanodiamonds are stardust grains commonly found in primitive meteorites. They survived the formation of the solar system and kept their own individuality. Measurements of trace-element isotopic signatures in these grains will help understanding heavy element nucleosynthesis in massive stars and dust formation from their ejecta. We have continued previous attempts to search for stable Pt isotope anomalies in nanodiamonds via trace element accelerator mass spectrometry (TEAMS). The installation of a new injector beam line at the VERA facility allowed studying low traces of stable elements in different materials. Moreover, recent experiments showed that VERA provides the required measurement precision together with a low Pt machine background. Here, we observed for the first time an indication for enhancements of 198Pt/195Pt isotope ratios in two diamond residues prepared by different chemical separation techniques from the Allende meteorite. Variations in other isotopic ratios were within analytical uncertainty, and no anomaly was identified in a third diamond fraction.

15.
Nucl Instrum Methods Phys Res B ; 294(2-2): 160-164, 2013 Jan.
Article in English | MEDLINE | ID: mdl-23565016

ABSTRACT

VERA, the Vienna Environmental Research Accelerator, is especially equipped for the measurement of actinides, and performs a growing number of measurements on environmental samples. While AMS is not the optimum method for each particular plutonium isotope, the possibility to measure 239Pu, 240Pu, 241Pu, 242Pu and 244Pu on the same AMS sputter target is a great simplification. We have obtained a first result on the global fallout value of 244Pu/239Pu = (5.7 ± 1.0) × 10-5 based on soil samples from Salzburg prefecture, Austria. Furthermore, we suggest using the 242Pu/240Pu ratio as an estimate of the initial 241Pu/239Pu ratio, which allows dating of the time of irradiation based solely on Pu isotopes. We have checked the validity of this estimate using literature data, simulations, and environmental samples from soil from the Salzburg prefecture (Austria), from the shut down Garigliano Nuclear Power Plant (Sessa Aurunca, Italy) and from the Irish Sea near the Sellafield nuclear facility. The maximum deviation of the estimated dates from the expected ages is 6 years, while relative dating of material from the same source seems to be possible with a precision of less than 2 years. Additional information carried by the minor plutonium isotopes may allow further improvements of the precision of the method.

16.
AJNR Am J Neuroradiol ; 34(2): 366-72, 2013 Feb.
Article in English | MEDLINE | ID: mdl-22790249

ABSTRACT

BACKGROUND AND PURPOSE: Revascularization of large cerebral artery occlusion is the therapeutic goal in stroke therapy. Currently, many recanalization devices are in clinical use. This study compares the outcome parameters, efficacy, and safety of the new generation of stent-retriever devices with the well-established Merci retriever. MATERIALS AND METHODS: All patients who received endovascular mechanical recanalization therapy were prospectively registered. One hundred twenty-two patients were treated with either new stent retrievers, including the Trevo and Solitaire devices, or the Merci retriever system. Recanalization of the occluded vessel was assessed in accordance with the modified TICI score, and outcome parameters, including the NIHSS and mRS scores, were documented. Clinical status was recorded after neurointervention, at time of discharge, and after 90 days. RESULTS: The mean age of all patients was 68 years; 54% were male, with no statistical differences in demographics between both groups. Successful recanalization (TICI 3 and TICI 2b) was achieved in 82% of patients treated with stent retrievers compared with 62% of patients treated with Merci retrievers (P = .016). In the 90-day follow-up, 65% of patients treated with stent retrievers and 35% of those treated with the Merci had achieved a good (mRS = 0-2) clinical outcome (P = .002). Patients treated with stent retrievers had a significantly shorter treatment time (72 versus 122 minutes, P < .01) and less severe intracerebral hemorrhages (10% versus 28%, P < .01). CONCLUSIONS: Patients treated with Trevo and Solitaire stents had a better revascularization rate, better clinical outcome, and lower complication rate than patients treated with the Merci retriever.


Subject(s)
Cerebral Revascularization/instrumentation , Device Removal/instrumentation , Infarction, Middle Cerebral Artery/surgery , Stents , Thrombectomy/instrumentation , Acute Disease , Aged , Brain Ischemia/diagnostic imaging , Brain Ischemia/drug therapy , Brain Ischemia/surgery , Cerebral Angiography , Cerebral Hemorrhage/prevention & control , Cerebral Revascularization/adverse effects , Cerebral Revascularization/methods , Device Removal/adverse effects , Device Removal/methods , Female , Follow-Up Studies , Humans , Infarction, Middle Cerebral Artery/diagnostic imaging , Infarction, Middle Cerebral Artery/drug therapy , Male , Postoperative Complications/prevention & control , Prospective Studies , Thrombectomy/adverse effects , Thrombectomy/methods , Thrombolytic Therapy , Tomography, X-Ray Computed , Treatment Outcome
17.
Sci Total Environ ; 430: 231-6, 2012 Jul 15.
Article in English | MEDLINE | ID: mdl-22664456

ABSTRACT

(129)I and (127)I concentrations in animal thyroids coming from several regions of Argentina were determined by accelerator mass spectrometry (AMS) and gas chromatography (GC), respectively. The measured (129)I/(127)I ratios, ranging from 3 × 10(-12) to 4 × 10(-10), are significantly lower than those typical for areas in the northern hemisphere (10(-10)-10(-7)). The (129)I concentrations show a clear dependence with latitude and season, which can be understood considering tropospheric circulation patterns, possible (129)I sources and regional precipitation rates.


Subject(s)
Air Pollutants, Radioactive/analysis , Environmental Exposure , Iodine/analysis , Thyroid Gland/chemistry , Animals , Argentina , Cattle , Chromatography, Gas/veterinary , Environmental Monitoring , Iodine Radioisotopes/analysis , Mass Spectrometry/veterinary , Seasons
18.
Interv Neuroradiol ; 18(2): 208-12, 2012 Jun.
Article in English | MEDLINE | ID: mdl-22681738

ABSTRACT

Retreatment options after the use of the newly launched Woven EndoBridge cerebral aneurysm embolization device (WEB II) are mostly unknown. Nine months after WEB II implantation, a 55-year-old female patient presented with regrowth of an MCA aneurysm. For the first time, standard balloon-assisted coiling was used to close the regrown aneurysm proximal to the WEB II implant. We report on the feasibility and safety of balloon-assisted coiling after implantation of the WEB II device.


Subject(s)
Blood Vessel Prosthesis , Embolization, Therapeutic/instrumentation , Intracranial Aneurysm/surgery , Angiography, Digital Subtraction , Cerebral Angiography , Female , Humans , Intracranial Aneurysm/diagnostic imaging , Middle Aged , Prosthesis Design
19.
Radiat Res ; 174(2): 137-45, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20681780

ABSTRACT

The detection of (41)Ca atoms in tooth enamel using accelerator mass spectrometry is suggested as a method capable of reconstructing thermal neutron exposures from atomic bomb survivors in Hiroshima and Nagasaki. In general, (41)Ca atoms are produced via thermal neutron capture by stable (40)Ca. Thus any (41)Ca atoms present in the tooth enamel of the survivors would be due to neutron exposure from both natural sources and radiation from the bomb. Tooth samples from five survivors in a control group with negligible neutron exposure were used to investigate the natural (41)Ca content in tooth enamel, and 16 tooth samples from 13 survivors were used to estimate bomb-related neutron exposure. The results showed that the mean (41)Ca/Ca isotope ratio was (0.17 +/- 0.05) x 10(-14) in the control samples and increased to 2 x 10(-14) for survivors who were proximally exposed to the bomb. The (41)Ca/Ca ratios showed an inverse correlation with distance from the hypocenter at the time of the bombing, similar to values that have been derived from theoretical free-in-air thermal-neutron transport calculations. Given that gamma-ray doses were determined earlier for the same tooth samples by means of electron spin resonance (ESR, or electron paramagnetic resonance, EPR), these results can serve to validate neutron exposures that were calculated individually for the survivors but that had to incorporate a number of assumptions (e.g. shielding conditions for the survivors).


Subject(s)
Calcium Radioisotopes/analysis , Dental Enamel/radiation effects , Nuclear Weapons , Female , Half-Life , Humans , Japan , Male , Neutrons , Particle Accelerators , Radiation Protection/methods , Survivors , Tooth/radiation effects
20.
Radiat Res ; 174(2): 146-54, 2010 Aug.
Article in English | MEDLINE | ID: mdl-20681781

ABSTRACT

(41)Ca is produced mainly by absorption of low-energy neutrons on stable (40)Ca. We used accelerator mass spectrometry (AMS) to measure (41)Ca in enamel of 16 teeth from 13 atomic bomb survivors who were exposed to the bomb within 1.2 km from the hypocenter in Hiroshima. In our accompanying paper (Wallner et al., Radiat. Res. 174, 000-000, 2010), we reported that the background-corrected (41)Ca/Ca ratio decreased from 19.5 x 10(-15) to 2.8 x 10(-15) with increasing distance from the hypocenter. Here we show that the measured ratios are in good correlation with gamma-ray doses assessed by electron paramagnetic resonance (EPR) in the same enamel samples, and agree well with calculated ratios based on either the current Dosimetry System 2002 (DS02) or more customized dose estimates where the regression slope as obtained from an errors-in-variables linear model was about 0.85. The calculated DS02 neutron dose to the survivors was about 10 to 80 mGy. The low-energy neutrons responsible for (41)Ca activation contributed variably to the total neutron dose depending on the shielding conditions. Namely, the contribution was smaller (10%) when shielding conditions were lighter (e.g., outside far away from a single house) and was larger (26%) when they were heavier (e.g., in or close to several houses) because of local moderation of neutrons by shielding materials. We conclude that AMS is useful for verifying calculated neutron doses under mixed exposure conditions with gamma rays.


Subject(s)
Calcium Radioisotopes/analysis , Dental Enamel/radiation effects , Nuclear Warfare , Survivors , Tooth/radiation effects , Conservation of Natural Resources , Gamma Rays/adverse effects , Housing/standards , Humans , Japan , Neutrons , Particle Accelerators , Retrospective Studies
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