From protoplanetary disks to prebiotic amino acids and the origin of the genetic code
Bibliographic record
Abstract
Introduction The robust formation of planets as well as abundant sources of water and organic molecules are likely to be important prerequisites for the wide-spread appearance of life in the cosmos. The nebular hypothesis of Kant and Laplace was the first to propose that the formation of planets occurs in gaseous disks around stars. The construction of new infrared and submillimetre observatories over the last decade and a half has resulted in the discovery of protoplanetary discs around most, if not all, forming stars regardless of their mass (e.g., reviews by Meyer et al. (2006), Dutrey et al. (2006)). The recent discoveries of extrasolar planets in over a hundred planetary systems provides good evidence that Jovian planets, at least, may be relatively abundant around solar-like stars (see Chapter 1). These results beg the question of whether protoplanetary disks are also natural settings for the manufacture of the molecular prerequisites for life. Life requires water and organic molecules such as amino acids, sugars, nucleobases, and lipids as building blocks out of which biological macromolecules and cellular structures are made, and many of these can be manufactured in protoplanetary disks. In the first part of this chapter we review the properties of protoplanetary disks and how planets are believed to form within them. We then consider the evidence that these disks may be a major source of the water and biomolecules available for the earliest life, as on the Earth.
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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 | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.008 | 0.004 |
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".