Effects of spaceflight and cage design on abdominal muscles of male rodents
Bibliographic record
Abstract
We examined the effects of a 16-day spaceflight mission on the size of muscle fibers in the rectus abdominis, external oblique and transversus abdominis muscles of adult male Fisher rats. The rats were individually housed in orbit, in contrast to the one previous spaceflight investigation of the same muscles, where the rats were group-housed pregnant females. The cross-sectional area of the muscle fibers was used as a measure of muscle atrophy or hypertrophy. The transversus, which is presumed to be the primary expiratory muscle and consequently works against internal hydrostatic pressures that are not likely to change much between 1 G and weightlessness, did not change in size. However, both the rectus abdominis (a spinal flexor) and the external oblique (a rotator of the torso), which resist gravity in the 1 G environment, showed significant signs of atrophy after extended exposure to microgravity. The atrophy of the external oblique was diametrically opposite to hypertrophy of the same muscle observed in group-housed rodents previously exposed to spaceflight. Although the two missions differed in several factors, such as the gender of the rats and mission duration, we believe that housing of the animals was the key factor that accounted for the different responses of the external oblique. Previous research has shown that group-housed rats in spaceflight exhibited seven times more rotations of their torsos than matched ground controls. Thus unloading of the musculoskeletal system may not be achieved in weightlessness when animals have the freedom to interact with each other.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".