The sphere in a uniform RF field—Revisited
Bibliographic record
Abstract
Abstract We consider eddy current generation in weakly conducting spheres as a means to characterize RF power dissipation over the frequency range 0.1–1.2 MHz, which is relevant to MRI in very low magnetic fields. We provide a complete, yet simple, theoretical analysis of the homogeneous sphere in a uniform RF field and summarize expressions for the current density, power dissipation, and magnetic field for the limiting case of the nonmagnetic conducting sphere. Experiments are performed on spherical saline phantoms using a whole‐body B1‐coil as the RF field source. Changes in the quality factor and magnetic field profile of the coil are measured and used to extract a value for conductivity of the saline solution. This conductivity is known independently from the NaCl concentration in the phantom. Excellent agreement between the two values confirms the theoretical analysis. © 2007 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 31B: 191–202, 2007
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".