173102 research outputs found
Sort by
Unraveling the Heterogeneity of ALS_A Call to Redefine Patient Stratification for Better Outcomes in Clinical Trials
No full textPerforming publics of science in the COVID-19 pandemic: A qualitative study in Austria, Bolivia, Germany, Italy, Mexico, and Portugal
No full textIntermolecular Enantioselective Amination Reactions Mediated by Visible Light and a Chiral Iron Porphyrin Complex
No full textFormalizing ethical principles within AI systems: experts’ opinions on why (not) and how to do it
No full textPractical Application of Multivendor MRI-Based R2* Mapping for Liver Iron Quantification at 1.5 T and 3.0 T.
No full textBACKGROUND: Recent multicenter, multivendor MRI-based R2* vs. liver iron concentration (LIC) calibrations (i.e., MCMV calibrations) may facilitate broad clinical dissemination of R2*-based LIC quantification. However, these calibrations are based on a centralized offline R2* reconstruction, and their applicability with vendor-provided R2* maps is unclear.
PURPOSE: To determine R2* ranges of agreement between the centralized and three MRI vendors' R2* reconstructions.
STUDY TYPE: Prospective.
SUBJECTS: Two hundred and seven subjects (mean age 37.6 ± 19.6 years; 117 male) with known or suspected iron overload from four academic medical centers.
FIELD STRENGTH/SEQUENCE: Standardized multiecho spoiled gradient echo sequence at 1.5 T and 3.0 T for R2* mapping and a multiple spin-echo sequence at 1.5 T for LIC quantification. MRI vendors: GE Healthcare, Philips Healthcare, and Siemens Healthineers.
ASSESSMENT: R2* maps were generated using both the centralized and vendor reconstructions, and ranges of agreement were determined. R2*-LIC linear calibrations were determined for each site, field strength, and reconstruction and compared with the MCMV calibrations.
STATISTICAL TESTS: Bland-Altman analysis to determine ranges of agreement. Linear regression, analysis of covariance F tests, and Tukey's multiple comparison testing to assess reproducibility of calibrations across sites and vendors. A P value <0.05 was considered significant.
RESULTS: The upper limits of R2* ranges of agreement were approximately 500, 375, and 330 s-1 for GE, Philips, and Siemens reconstructions, respectively, at 1.5 T and approximately 700 and 800 s-1 for GE and Philips, respectively, at 3.0 T. Within the R2* ranges of agreement, vendor R2*-LIC calibrations demonstrated high reproducibility (no significant differences between slopes or intercepts; P ≥ 0.06) and agreed with the MCMV calibrations (overlapping 95% confidence intervals).
DATA CONCLUSION: Based on the determined upper limits, R2* measurements obtained from vendor-provided R2* maps may be reliably and practically used to quantify LIC less than approximately 8-13 mg/g using the MCMV calibrations and similar acquisition parameters as this study.
EVIDENCE LEVEL: 1 TECHNICAL EFFICACY: Stage 3
Paving the way for CO2-Plume Geothermal (CPG) systems: A perspective on the CO2 surface equipment
No full textSubsurface reservoirs play an important role in decarbonizing the energy sector, be it through geothermal
energy production or carbon capture and storage. In recent years, there has been an increasing interest in
CO2-Plume Geothermal systems, which combine carbon sequestration with geothermal, using CO2 instead
of water as a subsurface heat and pressure energy carrier. Since CO2-Plume Geothermal systems are added
to full-scale CO2 Capture and Sequestration operations, all of the initially injected CO2 is ultimately stored.
CO2-Plume Geothermal, therefore constitutes of both CO2 Capture Utilization as well as Storage. This paper
assesses the huge technical potential of this technology, identifying a potentially highly relevant market for
CO2 equipment manufacturers and discusses the current research demand, based on the current state of the
art of CO2 equipment. Both temperature and pressure levels are significantly lower than CO2 turbine designs
investigated and proposed so far for other applications, such as waste heat recovery. For a depth of 5 km,
a typical one-stage radial turbine design might have a rotational speed of 23’000 rpm to 42’000 rpm and
an impeller diameter between 96 mm to 155 mm. Together with technology-specific requirements, due to
produced fluid impurities, it becomes evident that significant further development efforts are still necessary