A research and development roadmap to support applications of the enhanced BIOMASS methodology.

The International Atomic Energy Agency has coordinated an international project addressing enhancements of methods for modelling the biosphere in post-closure safety assessments of solid radioactive waste disposal. This has resulted in the enhanced BIOMASS methodology that is described elsewhere in this special issue. To a large degree, the enhancements to the BIOMASS methodology arose from experience gained in applying the original methodology, both in the context of other international projects and in assessments of existing or proposed disposal facilities for solid radioactive wastes. Here, this experience is used, together with information on the status of solid radioactive waste disposal programmes worldwide, to identify opportunities for applying the enhanced methodology and for learning from those applications. This provides a basis for identifying research and development to support application of the enhanced methodology in a variety of environmental settings. These research and development requirements include aspects related to climate change under a variety of forcing scenarios, landform development in climatic regimes ranging from cold, polar to arid, tropical, modelling of groundwater flow and contaminant transport in surface-water catchments where both fractured rock and porous sediments are present, and studies of the transport of key radioisotopes of elements central to major biogeochemical cycles, such as those of carbon, chlorine, sulphur and iodine. In addition, some remarks are made on aspects of the application of the enhanced methodology that could imply review and updating of regulations and regulatory guidance, e.g. in relation to the definition of representative persons or groups to be considered in assessments and in respect of approaches to the assessment of radiological impacts on non-human biota. Furthermore, consideration is given as to how the scientific and technical experience that has been gained and methods that have been developed in the context of solid radioactive disposal facilities could support management of contaminated sites and legacy facilities that are likely to require long-term management and stewardship.

A new 18 GHz room temperature electron cyclotron resonance ion source for highly charged ion beams.

An innovative 18 GHz HIISI (Heavy Ion Ion Source Injector) room temperature Electron Cyclotron Resonance (ECR) ion source (ECRIS) has been designed and constructed at the Department of Physics, University of Jyväskylä (JYFL), for the nuclear physics program of the JYFL Accelerator Laboratory. The primary objective of HIISI is to increase the intensities of medium charge states (M/Q ≅ 5) by a factor of 10 in comparison with the JYFL 14 GHz ECRIS and to increase the maximum usable xenon charge state from 35+ to 44+ to serve the space electronics irradiation testing program. HIISI is equipped with a refrigerated permanent magnet hexapole and a noncylindrical plasma chamber to achieve very strong radial magnetic confinement with Brad = 1.42 T. The commissioning of HIISI began in Fall 2017, and in Spring 2019, it has met the main objectives. As an example, the intensity of the Xe27+ ion beam has improved from 20 µA to 230 µA. In addition, the beam intensity of the Xe44+ ion beam has exceeded the requirement set by the irradiation testing program. The performance of HIISI is comparable to superconducting ECR ion sources with the same maximum microwave frequency of 18 GHz and a total power of 3 kW. For example, Ar16+ and Xe30+ ion beam intensities of 130 µA and 106 µA, respectively, have been obtained with a total microwave power of 3 kW distributed between 18, 17.4, and 14.5 GHz frequencies. The ion beams have been extracted through an 8 mm plasma electrode aperture using 15-17 kV extraction voltage. The latest development work, extracted ion beam intensities, special features, and future prospects of HIISI are presented in this paper.

Probabilistic assessment of the impact of bottom sediment on doses to humans from a groundwater-mediated radionuclide release in a farm-lake scenario.

Radionuclide transport with groundwater flow and subsequent doses to people are an aspect to be studied when assessing the long-term safety of geological nuclear waste repositories. A scenario where the radionuclide release migrates through a three-layer sediment structure of a lake in a farming environment is presented in this paper. The sediment column consists of deep (till), intermediate (glacio-aquatic sediment) and top layers (clay). The radionuclide release is assumed to enter the deep sediment layer from a bedrock fracture system at a rate of 1 Bq yr-1. The main objectives of the paper are to investigate the most contributing parameters, especially linked to the sediment layers, to the overall dose estimates for humans. The sensitivity analysis was conducted in two phases where the Morris method was used for screening and the Extended Fourier Amplitude Sensitivity Testing and Sobol's methods were used for estimating total-order indices. The studied radionuclides, 36Cl, 135Cs, 129I, 94Nb, 237Np, 90Sr, 99Tc and 238U, exhibit differences in how the sediment layers affect the concentration in the lake water used for drinking, irrigation and watering cattle and subsequently the dose conversion factors for humans through ingestion, inhalation and external radiation.

Climate change and landscape development in post-closure safety assessment of solid radioactive waste disposal: Results of an initiative of the IAEA.

The International Atomic Energy Agency has coordinated an international project addressing climate change and landscape development in post-closure safety assessments of solid radioactive waste disposal. The work has been supported by results of parallel on-going research that has been published in a variety of reports and peer reviewed journal articles. The project is due to be described in detail in a forthcoming IAEA report. Noting the multi-disciplinary nature of post-closure safety assessments, here, an overview of the work is given to provide researchers in the broader fields of radioecology and radiological safety assessment with a review of the work that has been undertaken. It is hoped that such dissemination will support and promote integrated understanding and coherent treatment of climate change and landscape development within an overall assessment process. The key activities undertaken in the project were: identification of the key processes that drive environmental change (mainly those associated with climate and climate change), and description of how a relevant future may develop on a global scale; development of a methodology for characterising environmental change that is valid on a global scale, showing how modelled global changes in climate can be downscaled to provide information that may be needed for characterising environmental change in site-specific assessments, and illustrating different aspects of the methodology in a number of case studies that show the evolution of site characteristics and the implications for the dose assessment models. Overall, the study has shown that quantitative climate and landscape modelling has now developed to the stage that it can be used to define an envelope of climate and landscape change scenarios at specific sites and under specific greenhouse-gas emissions assumptions that is suitable for use in quantitative post-closure performance assessments. These scenarios are not predictions of the future, but are projections based on a well-established understanding of the important processes involved and their impacts on different types of landscape. Such projections support the understanding of, and selection of, plausible ranges of scenarios for use in post-closure safety assessments.

Factors associated with in-hospital outcomes in 594 consecutive patients suffering from severe blunt chest trauma.

BACKGROUND AND AIMS: Blunt thoracic injury is a common cause for hospital admission after trauma. The effect of the number of rib fractures on the outcome is controversial. In this study, our hypothesis was that an increasing number of rib fractures correlates with mortality and hospital resource utilization. In addition to mortality, our focus was on the length of stay at hospital and in the intensive care unit, ventilator days, and the days in continuous positive airway pressure. MATERIAL AND METHODS: The present investigation is a retrospective study from a single trauma center. The study includes patients with severe thoracic injury (thoracic Abbreviated Injury Scale (AIS) > 2) admitted to hospital after blunt trauma. Patients with isolated thoracic spine injuries and patients who were dead on arrival were excluded. Vital signs, laboratory results on admission, given care, intensive care unit and hospital length of stay, injuries, and in-hospital mortality were collected for the study. RESULTS: A total of 594 patients from a 5-year period (2003-2007) were included in the study. The mean age of the patients was 45 years, and 76.9% of the patients were males. The average Injury Severity Score was 22, and the patients had on average 5.5 injuries. Overall mortality was 6.4%. In the multivariate analysis, the mortality was associated with base excess and tromboplastin time in admission. The number of rib fractures did not correlate with the outcome measures, but the presence of bilateral rib fractures correlated with the outcome measures other than mortality. CONCLUSIONS: The number of rib fractures does not correlate with mortality or the length of stay in the intensive care unit in blunt trauma patients with severe thoracic injury. Mortality in these patients correlated with the degree of hypoperfusion (base excess) and coagulation abnormalities (tromboplastin time) on admission.

The impact of pharyngeal fat tissue on the pathogenesis of obstructive sleep apnea.

PURPOSE: Obesity is the most important risk factor for obstructive sleep apnea (OSA); however, the exact underlying mechanisms are still not fully understood. The aim of this study was to examine the morphology of upper airways in overweight habitual snorers and in mild OSA patients. Furthermore, the associations between weight loss, parapharyngeal fat pad area and OSA were assessed in a 1-year randomised, controlled follow-up study originally conducted to determine the effects of lifestyle changes with weight reduction as a treatment of OSA. METHODS: Thirty-six overweight adult patients with mild OSA [apnea-hypopnea index (AHI) 5-15 events/h] and 24 weight-matched habitual snorers (AHI < 5 events/h) were included in the study. All patients underwent nocturnal cardiorespiratory recordings and multislice computed tomography (CT) of parapharyngeal fat pad area, the smallest diameter and area in naso-, oro- and hypopharynx, the smallest diameter and area of the whole pharyngeal airway, the distance from the hyoid bone to the mandibular plane and to cervical tangent as well as the distance between mandibular symphysis and cervical spine. In addition, OSA patients were further randomised to receive either an active 1-year lifestyle intervention with an early weight loss programme or routine lifestyle counselling. After 1 year, the cardiorespiratory recordings and CT scans were repeated. RESULTS: The pharyngeal fat pad area was significantly larger, and the distance from the hyoid bone to cervical spine was longer in patients with OSA than in habitual snorers (p = 0.002 and p = 0.018, respectively). The multiple regression analysis showed that besides a large pharyngeal fat pad area and a long distance from the cervical spine to hyoid bone, also a short distance from the mandibular symphysis to cervical tangent increased a risk to OSA. During the 1-year follow-up in OSA patients, the pharyngeal fat pad area and AHI decreased significantly in the intervention group (p = 0.003 and p < 0.001, respectively). CONCLUSIONS: In the early stages of OSA, the pharyngeal fat pad seems to play an important role in the development of disease in overweight patients. Furthermore, weight reduction by lifestyle intervention-based programme reduces both central obesity and pharyngeal fat pads, resulting in an improvement of OSA.

The effects of heat stress on cognition in persons with multiple sclerosis.

BACKGROUND: Heat sensitivity and cognitive deficits are typical manifestations of multiple sclerosis (MS). Although cognitive deficits are quite well characterized, practically no data exist on the effects of heat on cognitive performances in MS. OBJECTIVE: To assess the effects of short-term heat stress on cognitive functioning in subjects with MS. METHODS: A total of 23 heat-sensitive MS and 19 healthy control (HC) subjects participated. Moderate heat exposure took place in a Finnish sauna. Cognitive functioning was measured with tests of sustained attention and processing speed, the Paced Auditory Serial Addition Test (PASAT 3" and 2") and the computerized visual vigilance test, before, during and after heat exposure. RESULTS: During the heat exposure, the core body temperature of the MS group rose significantly more (p = 0.002) than that of the HC group. The heat stress worsened the performance of the MS group in the PASAT 3" (p = 0.025) but not in the other cognitive measures. The performance in the PASAT 3" was reversed almost to the baseline level only 1- h after the heat exposure. CONCLUSIONS: A significant increase in core body temperature during heat stress is associated with a mild and reversible worsening of the PASAT 3" performance, while visual vigilance performance seems to remain almost unaffected.

Forecasts of future terrain and vegetation types at Olkiluoto and implications for spatial and temporal aspects of biosphere modelling.

In Finland, a nuclear repository site is situated on the western coast where the current land uplift rate is 6mm/yr. A set of tools has been developed for predicting the future terrain and vegetation types, and for producing estimates of the site-specific parameter values for use in simplified radionuclide transport models. Although the landscape will change considerably within the next millennia, the likely changes are relatively predictable. By comparing the results to the site data, the effect of human activities can be at least partially quantified.

Three-dimensional respiratory-gated coronary MR angiography with reference to X-ray coronary angiography.

PURPOSE: To assess the clinical value of three-dimensional coronary MR angiography (CMRA) in the detection of significant coronary artery stenosis using conventional X-ray angiography as the standard reference. MATERIAL AND METHODS: Sixty-nine patients underwent X-ray coronary angiography and CMRA because of suspected or previously diagnosed coronary artery disease. MRI was performed with a 1.5-T whole body imaging system using ECG-triggered 3D gradient echo sequence with retrospective navigator echo respiratory gating and fat suppression. RESULTS: A total of 276 coronary artery segments were analyzed. The X-ray coronary angiography was normal in 22 patients. Significant proximal stenoses (exceeding 50%) or occlusions were present in 102 coronary artery segments. In all, 120 stenoses or occlusions were identified in CMRA. Sixteen percent of the coronary artery segments had to be excluded because of poor image quality. The overall sensitivity and specificity for MRA for identification of significant stenosis were 75% and 62%, respectively. CMRA correctly detected 89% of patients with at least one vessel disease, but 6 patients with coronary artery disease would have been missed. CONCLUSIONS: Because of the high data exclusion and false- negative case rate, CMRA with retrospective navigator echo triggering is at present not suitable as a clinical screening method in coronary artery disease.

Transthoracic three-dimensional echocardiography is as good as magnetic resonance imaging in measuring dynamic changes in left ventricular volume during the heart cycle in children.

AIMS: The purpose of the study was to assess the dynamic changes in left ventricular (LV) volume by transthoracic three-dimensional echocardiography (3DE) and to compare the results with those obtained by magnetic resonance imaging (MRI). METHODS AND RESULTS: Thirty healthy children were studied by digitized 3DE and Doppler, and by MRI. Three-dimensional echocardiography of LV was performed by using rotational acquisition from the transthoracic apical view with ECG gating and without respiratory gating. The acquisition of 3DE data took 10-15s. Three-dimensional echocardiography gave similar values to MRI for EDV, ESV and LVM measurements, and the results correlated well. Peak emptying rates by 3DE and MRI were -236.6 and -169.6ml/s and peak filling rates were 215.0 and 215.9ml/s, respectively. Dynamic changes of LV volumes during the heart cycle were detectable with both methods. CONCLUSION: Digitized 3DE performed in the outpatient clinic and MRI were both useful methods for studying the physiological volume changes in left ventricle in children. These methods may be used for further study of the systolic and diastolic function of the left ventricle in various clinical conditions.

Repeated 3D coronary MR angiography with navigator echo gating: technical quality and consistency of image interpretation.

The purpose of this study was to evaluate the technical quality of 3D coronary MR angiography (CMRA) with navigator echo and the consistency of image interpretation in repeated imaging sessions. Fourteen subjects underwent CMRA, 10 of whom were imaged twice. The coronary arteries (96 segments) were analyzed twice for hemodynamically significant stenoses. Signal-to-noise and contrast-to-noise ratios varied considerably between the two imagings. Fat saturation was poor or satisfactory in 37%; in 15% of the slabs, the severity of artifacts was moderate; and the overall quality was good to excellent in only 42% of the imagings. The intraobserver reproducibility was good (kappa = 0.54), but the consistency of interpretation for repeated CMRA was only satisfactory (kappa = 0.43). Sensitivities of 84 and 84% and specificities of 70 and 62% were obtained for the two readings. Although the reproducibility of image reading is good, 3D CMRA with navigator echo provides only fair technical consistency, and the frequently compromised image quality impairs the clinical utility of this technique.

Left atrial volume assessed by transthoracic three dimensional echocardiography and magnetic resonance imaging: dynamic changes during the heart cycle in children.

OBJECTIVE: To assess the dynamic changes in left atrial volume by transthoracic three dimensional echocardiography and compare the results with those obtained by magnetic resonance imaging (MRI). DESIGN AND PATIENTS: 30 healthy children (15 boys and 15 girls, aged 8 to 13 years) underwent examination by three dimensional echocardiography and MRI. METHODS: Three dimensional echocardiography of the left atrium was performed using rotational acquisition of planes at 18 degrees intervals from the parasternal window with ECG gating and without respiratory gating. Volume estimation by MRI was performed with a slice thickness of 4-8 mm and ECG triggering during breath holding in deep inspiration. A left atrial time-volume curve was reconstructed in each child. RESULTS: Left atrial maximum and minimum volumes averaged 24.0 ml/m(2) and 7. 6 ml/m(2) by three dimensional echocardiography, and 22.1 ml/m(2) and 11.9 ml/m(2) by MRI. The greater left atrial minimum volume in the latter was at least in part a result of breath holding. Dynamic changes in left atrial volume during the heart cycle were detectable by both methods. The higher temporal resolution of three dimensional echocardiography allowed a more precise evaluation of different phases. CONCLUSIONS: Three dimensional echocardiography and MRI were both useful methods for studying the physiological volume changes in the left atrium in children. These methods may be used for further study of the systolic and diastolic function of the heart.