Recovery of bone microarchitecture and density four years after spaceflight: two case studies
Bibliographic record
Abstract
Spaceflight is known to negatively impact bone health, but the duration of these effects remains unclear. These two case studies investigated bone microarchitecture, density, and remodelling up to 4 years after long-duration spaceflight, aiming to inform countermeasure development and guide future research efforts. High-resolution peripheral quantitative computed tomography (HR-pQCT) and dual X-ray absorptiometry (DXA) scans were conducted on two crew members at pre-flight and up to 48-months post-spaceflight. Both crew members exhibited significant bone loss in the tibia at return from spaceflight, while only one crew member showed losses in the radius. After 4 years of recovery, one crew member achieved full recovery, while the second experienced persistent trabecular deficits that were compensated by significant cortical thickening. These results provide insight into the need for tailored countermeasures and prolonged monitoring to optimize skeletal health for future long-duration space missions, with implications for bone health research on mechanical unloading and reloading.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.003 | 0.001 |
| 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".