Photoacoustic radio-frequency spectroscopy (PA-RFS): A technique for monitoring absorber size and concentration
Bibliographic record
Abstract
A photoacoustic technique for monitoring absorber size and concentration is presented. The technique relies on analyzing the power spectra of the radio-frequency signals and taking into account the receiving transducer response in order to remove system dependencies. By normalizing the power spectra, parameters derived from ultrasound tissue characterization (spectral slope and midband fit) can be obtained. Tissue mimicking phantoms were constructed using black polystyrene beads of various sizes and concentrations as absorbers. The spectral slope decreased by 0.63 dB/MHz when the size of the particle increased from 1 μm to 10 μm at every bead concentration. The midband fit was ~4 dB higher for the 10 μm particle and increased linearly with concentration. These results suggest that photoacoustic radiofrequency spectroscopy (PA-RFS) can potentially monitor changes in absorber size and concentration thus improving the ability of photoacoustic imaging to distinguish structural tissue variations.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| 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 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".