Interpreting δ <sup>13</sup> C Values Obtained on SOM from Ancient Maya Reservoirs and Depressions
Bibliographic record
Abstract
Elemental analyzer (EA) Isotope Ratio Mass Spectrometry was used to measure ∂ 13 C values on soil organic matter from reservoirs and depressions at the ancient Maya urban centers of Tikal, Guatemala and Yaxnohcah, Mexico. Variation in δ 13 C values on soil organic matter were > −2.0‰, which suggests enrichment from C4 plants including maize, other tropical grasses (Poaceae), and tropical sedges (Cyperaceae), CAM plants (Clusia sp.), and cyanobacteria (blue-green algae). Cyanobacteria were likely a major contributor to the 13C enrichment of soil organic matter in Maya reservoirs and depressions, which has obfuscated our understanding of ancient Maya maize production. It is possible that the Maya used cyanobacteria as a fertilizer, which enriched agricultural field soil organic matter.
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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 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 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".