Non-linear scattering from microbubble contrast agents in the 14-40 MHz range
Bibliographic record
Abstract
The non-linear scattering properties of microbubble contrast agents in the 14-40 MHz frequency range are investigated. Experiments were conducted as a function of pressure for two agents (Definity/sup TM/ and Optison/sup TM/) and polystyrene microbeads as control scatterers. For Definity/sup TM/, subharmonic (0.5f/sub 0/) and ultraharmonic (1.5f/sub 0/) scattering was substantial and strongly dependent on pressure up to 26 MHz. Optison/sup TM/ also exhibited sub- and ultraharmonic scattering, but these effects were weaker and found to persist up to 22 MHz. Second harmonic (2f/sub 0/) scattering for Definity/sup TM/, Optison/sup TM/ and the microbeads was strong and increased with pressure suggesting a significant component of 2f/sub 0/ agent signal was due to non-linear propagation. However, the ratio of 2f/sub 0/ to f/sub 0/ scattering was higher for agent than for microbeads (20 dB for Definity/sup TM/) after correcting for frequency dependent microbead scattering. A test for bubble destruction at 20 MHz revealed that a significant subpopulation of bubbles could be disrupted. We conclude that non-linear scattering can be produced with high frequency ultrasound technology and currently available agents. This suggests the possibility of implementing non-linear detection and destruction techniques at high frequencies.
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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 | 0.000 | 0.000 |
| 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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".