Anisotropy of ultrasonic backscatter by blood in shear flow: Monte Carlo simulations
Bibliographic record
Abstract
The relation between the heterogeneous microstructure of biological tissues and their measurable scattering properties is still poorly understood. In particular, physical explanation of blood hyperechogenicity when submitted to low shear forces appears incomplete. To quantify the contribution of erythrocyte aggregation to this phenomenon, Monte Carlo 2D simulations of the red cell spatial pattern are performed. The backscattering coefficient of blood at 5 and 40 MHz is estimated for two orthogonal insonification angles, as a function of effective adhesive energy V/sub agg/ and anisotropy index a. Isotropic aggregation resulted in an enhanced backscatter at 5 MHz (+7 dB) but had a minor effect at 40 MHz. Addition of spatial anisotropy essentially diminished the backscatter at 5 MHz, independently on the angle, whereas at 40 MHz, the perpendicular backscatter largely exceeded the parallel backscatter (+6 dB). This showed that anisotropy present in the spatial microscopic pattern can be detected in the high frequency scattering regime, while low frequency backscatter is more affected by larger geometrical features as the aggregate size.
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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 | 0.004 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.002 | 0.001 |
| 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".