Bibliographic record
Abstract
This thesis investigates the effect of constant or periodic boundary forcing on the spatio-temporal dynamics of open flows of media whose kinetics can be oscillatory, bistable or excitable. The systems investigated are those where the flow profile is uniform (“plug-flow”) and the flow coefficients are equal. Oscillatory and excitable media are investigated experimentally using the ferroin-catalysed Belousov-Zhabotinsky (BZ) reaction medium. Given appropriate flow conditions, stationary space-periodic structures are observed. I refer to them as “flow-distributed oscillations” (FDO) and “flow-stabilised dissipative structures” in oscillatory and excitable media, respectively. Periodic forcing of oscillatory media leads to travelling waves. They propagate upstream or downstream with either constant or oscillatory velocity. The constant velocity waves are in quantitative agreement with predictions from spatio-temporal phase dynamics. The oscillatory waves are also phase waves. The effect of periodic forcing on bistable and excitable media or on media having a Hopf or Turing unstable steady state is discussed in the context of persistent, downstream advected space-periodic structures. These waves have velocities that are equal to that of the flow and wavelengths that are equal to the product of the flow velocity and the period of the boundary forcing. The relevance of open reactive flow to biological morphogenesis is discussed. In many organisms, space-periodic structures are formed sequentially, one after the other, during axial growth of the embryo. Axial growth is shown to be equivalent to an open flow. Relative to the growth/flow boundary, the space-periodic structure has a velocity that is equal to the growth/flow velocity. Recent experiments established the operation of a cell-autonomous oscillator in early vertebrate development and showed that the formation of space-periodic structure is preceded by gene expression waves with an intricate spatio-temporal dynamics. They are mimicked in a chemical flow system, which reproduces four of the principal features of the developmental process. The predictions of an FDO-based model are compared to experimental observations and different kinetic schemes are investigated. This reveals a powerful mechanism of wave pattern formation that captures the essence of the regulation of morphogenesis during early development.
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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) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| 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".