Noninvasive investigation of asymmetrically conjoined tripus twins with features of rachipagus, parapagus dicephalus, and cephalopagus
Bibliographic record
Abstract
A hypothetical mechanism for conjoined twinning postulated by Spencer ([2003] Developmental Malformations and Clinical Implications, Baltimore: Johns Hopkins University Press, p 1-476) suggests that, after separation, monovular twins fuse in one of eight predictable homologous sites. The tripus fetal specimen under study embodies characteristics of three types therefore preventing it from classification into a simple variant of any one of the eight twin types described by Spencer. The aim of this study was to reveal internal structural anomalies of the fetal specimen by using magnetic resonance imaging and computerized tomography. Dorsally appended to the primary twin is a secondary head mass (brain tissue and ocular globe) and two spinal columns converging at T4/T5, suggesting rachipagus twinning. The ventral orientation of the secondary twin's (right lateral) lower limb suggests parapagus twinning. The caudal divergence of the spinal columns and the presence of a secondary hemipelvis, separate from the primary pelvis, suggest cephalopagus twinning. Measurements of the long bones indicate a gestational age of ∼20-23 weeks. Secondary malformations of the primary fetal body include anencephaly, cleft palate, renal agenesis, decreased left ventricular outflow, and a prematurely terminating descending aorta. This study demonstrates the possibility of using current imaging techniques to study very old, formalin-preserved human material for documentation and scientific discussion without destroying the specimen, thus keeping it intact for posterity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.002 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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 teacher head, 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".