568 research outputs found
D-dimer to Rule Out Pulmonary Embolism in Renal Insufficiency
No full textBACKGROUND
D-dimer levels are often elevated in renal insufficiency. The diagnostic accuracy of D-dimer to rule out pulmonary embolism in patients with renal insufficiency is unclear.
METHODS
We evaluated the data of patients presenting to our Emergency Department and receiving computed tomography angiography to rule out pulmonary embolism with measurement of D-dimer and creatinine. Glomerular filtration rate was calculated using the Chronic Kidney Disease Epidemiology Collaboration formula.
RESULTS
There were 1305 patients included; 1067 (82%) had an estimated glomerular filtration rate (eGFR) exceeding 60 mL/min, 209 (16%) 30-60 mL/min, and 29 (2%) 60 mL/min was 96% (confidence interval [CI], 0.93-0.99) and 100% (CI, 100-100) for those with 30-60 mL/min, while specificity decreased significantly with impaired renal function. Area under the curve of the receiver operating characteristic for D-dimer was 0.734 in patients with an eGFR of >60 mL/min, and 0.673 for 30-60 mL/min.
CONCLUSIONS
D-dimer levels were elevated in patients with an eGFR <60 mL/min, but proved to be highly sensitive for the exclusion of pulmonary embolism. However, because almost all patients with impaired renal function had elevated D-dimer irrespective of the presence of pulmonary embolism, studies should be performed to determine renal function-adjusted D-dimer cutoffs
Radiation level in the DEMO tokamak complex due to activated flowing water: Impact on the architecture of the building
No full textThe radiation protection issues linked to the activated cooling water coming from the in-vessel components of a fusion reactor to the ex-vessel regions are important design and safety constraints in the building layout definition, as demonstrated at ITER. To tackle these issues more rigorously already in the pre-conceptual design of DEMO some relevant activation and neutronic studies have been performed for the re-definition of a preliminary architecture of the tokamak complex. The design conditions of the Water Cooled Lithium Lead (WCLL) Breeding Blanket (BB) concept have been considered as well as those of the Helium Cooled Pebble Bed (HCPB). The radiation environment in those areas of the building hosting the pipes carrying activated water devoted to the cooling of the First Wall/limiter and divertor has been characterized in terms of decay photons and secondary neutron emissions, which are emitted by N16 and N17 radionuclides. In particular, the feasibility of placing radiation sensitive equipment near flowing activated water is evaluated by calculating accumulated dose in silicon and neutron flux. Viability for manual maintenance activities is assessed by calculating biological dose rate for workers due to Activated Corrosion Products (ACP). The values achieved are then compared to applicable limits. Identification of problematic areas stimulated the examination of some design proposals to improve shielding materials and components
DEMO toroidal field coil fast discharge unit integration studies
No full textThe Fast Discharge Units (FDUs) of the Superconducting (SC) Toroidal Field (TF) coils in the European demonstration fusion power plant DEMO warrant the machine integrity over its full lifetime against severe failure events, such as SC coil quenches or any other plant events requiring the safe TF magnet system discharge. A low (75 kA) and a high current (105 kA) configuration are under study for the TF coils for DEMO. The FDUs must be extremely reliable for the purpose of commutating in short time (∼1 s) the currents and to discharge the TF magnets safely into resistors outside of the tokamak building. Malfunctions of the FDUs must be avoided. The FDUs are considered as Safety Important Class (SIC) components that need to discharge high amounts of energy of about 161 GJ (@75 kA) resp. 118 GJ (@105 kA) stored in the DEMO TF coils. The TF FDUs Circuit Breakers (CBs) shall be installed in the lower level of the tokamak to minimize the length of the connecting busbars. The FDUs integration is challenging because of the high neutron and gamma radiation and stray magnetic fields of the tokamak. Since in DEMO the neutron fluence over lifetime is much higher than in ITER, the problems of using FDUs with electronic subsystems was expected to be more severe, so that their integration has been considered from the beginning of the DEMO project. Sufficient shielding or possible re-positioning of the whole FDUs or sensitive FDU components compared to ITER are being investigated, to reduce the neutron fluxes and neutron and gamma ray fluences. Alternative concepts, e.g., fully mechanical CBs are studied in the EUROfusion Work Package Plant Electrical System (WPPES) in parallel. This paper presents the CAD integration work on the DEMO TF FDUs supported by neutronics assessments. It is assumed the same FDU technology as in ITER. The magnet feeder ́s integration is commenced at the same time
Renal Function-Adjusted D-Dimer Levels in Critically Ill Patients With Suspected Thromboembolism.
No full textOBJECTIVES
Diagnosing thromboembolic disease typically includes D-dimer testing and use of clinical scores in patients with low to intermediate pretest probability. However, renal dysfunction is often observed in patients with thromboembolic disease and was previously shown to be associated with increased D-dimer levels. We seek to validate previously suggested estimated glomerular filtration rate-adjusted D-dimer cutoff levels. Furthermore, we strive to explore whether the type of renal dysfunction affects estimated glomerular filtration rate-adjusted D-dimer test characteristics.
DESIGN
Single-center retrospective data analysis from electronic healthcare records of all emergency department patients admitted for suspected thromboembolic disease.
SETTING
Tertiary care academic hospital.
SUBJECTS
Exclusion criteria were as follows: age less than 16 years old, patients with active bleeding, and/or incomplete records.
INTERVENTIONS
Test characteristics of previously suggested that estimated glomerular filtration rate-adjusted D-dimer cutoff levels (> 333 µg/L [estimated glomerular filtration rate, > 60 mL/min/1.73 m], > 1,306 µg/L [30-60 mL/min/1.73 m], and > 1,663 µg/L [< 30 mL/min/1.73 m]) were validated and compared with the conventional D-dimer cutoff level of 500 µg/L.
MAIN RESULTS
A total of 14,477 patients were included in the final analysis, with 467 patients (3.5%) diagnosed with thromboembolic disease. Renal dysfunction was observed in 1,364 (9.4%) of the total population. When adjusted D-dimer levels were applied, test characteristics remained stable: negative predictive value (> 99%), sensitivity (91.2% vs 93.4%), and specificity (42.7% vs 50.7%) when compared with the conventional D-dimer cutoff level to rule out thromboembolic disease (< 500 µg/L). Comparable characteristics were also observed when adjusted D-dimer cutoff levels were applied in patients with acute kidney injury (negative predictive value, 98.8%; sensitivity, 95.8%; specificity, 39.2%) and/or "acute on chronic" renal dysfunction (negative predictive value, 98.0%; sensitivity, 92.9%; specificity, 48.5%).
CONCLUSIONS
D-Dimer cutoff levels adjusted for renal dysfunction appear feasible and safe assessing thromboembolic disease in critically ill patients. Furthermore, adjusted D-dimer cutoff levels seem reliable in patients with acute kidney injury and "acute on chronic" renal dysfunction. In patients with estimated glomerular filtration rate less than 60 mL/min/1.73 m, the false-positive rate can be reduced when estimated glomerular filtration rate-adjusted D-dimer cutoff levels are applied
Status of ITER material activation experiments at JET
No full textActivities under the EURO fusion work package JET3 programme have been established to enable the technological exploitation of the planned JET experiments over the next few years, which culminates in a D-T experimental campaign, DTE-2. In the areas of nuclear technology and nuclear safety the programme offers a unique opportunity to provide experimental data that is relevant to ITER. The key purpose of the collected data will be to support bench marking and validation activities relating to neutronics and activation codes, and associated nuclear data, that are used to predict the nuclear behavior of ITER component and materials, during and after operations.This paper details the status and key issues of the ongoing ACT sub-project under work package JET3, which aims to take advantage of the large 14 MeV neutron fluence expected during JET DTE-2 to irradiate samples of real ITER materials used in the manufacturing of the main in-vessel tokamak components. The materials considered, with specified minor elemental impurity levels, include: Nb3Sn, SS316L steels from a range of manufacturers, SS304B, Alloy 660, W, CuCrZr, OF-Cu, XM-19, Al bronze, NbTi and EUROFER. The activities include provision for measurement of nuclide activities for each material and comparison against the predicted quantities through calculation with the FISPACT-II inventory code. Included here are key pre-analysis results for the selected ITER irradiation samples, and corresponding optimization of dosimetry foils (Ti, Mn, Co, Ni, Y, Fe, Co, Sc, Ta) that will be irradiated at selected positions inside JET irradiation stations in order to determine the neutron spectrum. Preliminary experimental activation results through recent JET D-D operations are discussed. (C) 2017 Elsevier B.V. All rights reserved
Displacement damage parameters for fusion breeder blanket materials based on BCA computer simulations
No full textDisplacement damage calculations in light mass and polyatomic fusion reactor materials based on realistic computer simulations
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