Long-range diffusion of hyperpolarized <sup>3</sup>He in explanted normal and emphysematous human lungs via magnetization tagging
Bibliographic record
Abstract
Long-range diffusivity of hyperpolarized 3He gas was measured from the decay rate of sinusoidally modulated longitudinal nuclear magnetization in three normal donor and nine severely emphysematous explanted human lungs. This (long-range) diffusivity, which we call Dsec, is measured over seconds and centimeters and is approximately 10 times smaller in healthy lungs (0.022 cm2/s) than the more traditionally measured Dmsec, which is measured over milliseconds and submillimeters. The increased restriction of Dsec reflects the complex, tortuous paths required to navigate long distances through the maze of branching peripheral airways. In emphysematous lungs, Dsec is substantially increased, with some regions showing nearly the unrestricted value of the self-diffusion coefficient (0.88 cm2/s for dilute 3He in air, a 40-fold increase). This suggests the presence of large collateral pathways opened by alveolar destruction that bypass the airways proper. This destruction was confirmed by comparison with histology in seven lungs and by removal of trapped gas via holes in the pleural surface in five lungs.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
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".