Bibliographic record
Abstract
The molecular spring titin is the primary structure providing passive force inskeletal muscle sarcomeres1, and titin has been said to hold the key to the visco-elasticproperties of muscles2. Specifically, it has been argued that unfolding/refolding ofthe Ig domains of titin causes the visco-elastic behavior, but Ig domain refoldingonly occurs at specific sarcomere lengths and forces2. Therefore, the purpose of thisstudy was to test the hypothesis that muscle is highly visco-elastic in regions of Igdomain unfolding/refolding while it is virtually elastic when refolding is prevented.Ten myofibrils from rabbit psoas were isolated and prepared for mechanical testingas described previously3. Testing involved passive stretch release cycles of variousmagnitudes. First, three stretch shortening cycles were performed between averagesarcomere lengths of 2.6 to 4.6 mm. Then, myofibrils were rested for ten minutes atslack length (1.8 mm) and the initial stretch-shortening cycles were repeated two moretimes. Following another rest of ten minutes, myofibrils were stretched to an averagesarcomere length of approximately 4.6 mm and then shortened and stretched by 0.5,1.0, or 1.5 mm/per sarcomere ten times. When stretched and released from 2.6 to4.6 mm and back, myofibrils exhibited a highly visco-elastic behavior and Ig domainun/refolding is known to occur2,3. However, when myofibrils were cycled ten timesby a short magnitude (e.g 0.5 mm) starting at an average sarcomere length of 4.6 mm,titin behaved virtually elastic and Ig domain refolding was prevented2,3. We concludefrom these results that myofibrils behave visco-elastically in regions where Ig domainunfolding/refolding is known to occur, while they behave essentially elastic whenoperating in regions where Ig domain refolding is prevented. Therefore, a muscle’spassive properties may change from highly visco-elastic to virtually purely elasticdepending on the kinetics of Ig domain un/re folding.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.002 |
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".