{"artifact_id":"L1-043","layer":"L1","title":"Functional MRI (BOLD)","domain":"Medical Imaging","sub_domain":"BOLD-contrast brain functional imaging","physics_fingerprint":{"L_DAG":4.0,"title":"Functional MRI (BOLD)","domain":"Medical Imaging","carrier":"radio_wave","primitives":["L.rf_excitation","L.gradient_encoding","L.T2_star_weighting","int.temporal"],"sub_domain":"BOLD-contrast brain functional imaging","noise_model":"gaussian","problem_class":"nonlinear_inverse","solution_space":"4D_BOLD_signal","difficulty_delta":10,"integration_axis":"temporal","sensing_mechanism":"mri_fourier_encoding"},"observable_profile":{"metric":"PSNR_dB","regime":"Existence of the recovered 4D BOLD signal is guaranteed within the declared Omega bounds. Uniqueness is local rather than global (non-convex landscape); convergence depends on initialisation and priors. Stability is moderately conditioned (kappa_eff ~= 25); physiological_noise dominates the stability cliff; motion and the remaining mismatch parameters contribute higher-order bias terms. Additive gaussian thermal/electronic noise sets the irreducible data-fidelity floor, while TV / wavelet-sparsity / deep priors stabilise recovery at the ill-conditioned end of Omega.","secondary":"SSIM"},"size_tiers":{"center_spec":{"omega":{"H":64,"W":64,"Z":40,"TR_s":2.0,"TE_ms":30,"SNR_dB":15,"motion":0.0,"N_frames":300,"physiological_noise":0.02,"susceptibility_artifact":0.0},"input_format":"measurement_only","problem_class":"fmri","forward_operator":"fmri_forward","epsilon_fn_center":"12.0"},"omega_bounds":{"H":32,"W":32,"Z":[16,100],"TR_s":[0.5,5.0],"TE_ms":[15,80],"SNR_dB":[0.0,30.0],"motion":[0.0,0.5],"N_frames":[50,1000],"multi_echo_bias":[0.0,0.2],"acquisition_jitter":[0.0,0.1],"physiological_noise":[0.0,0.2],"susceptibility_artifact":[0.0,0.3]},"epsilon_bounds":{"psnr_db":[5.0,45.0]},"allowed_problem_classes":["fmri"],"allowed_omega_dimensions":["H","W","Z","N_frames","TR_s","TE_ms","SNR_dB","physiological_noise","motion","susceptibility_artifact","physiological_noise","motion","susceptibility_artifact","acquisition_jitter","multi_echo_bias"],"allowed_forward_operators":["fmri_forward"]},"hardness_fn":{"type":"epsilon_fn","delta":10,"kappa":500,"metric":"PSNR_dB"},"initiator_dataset":[{"name":"primary","weight":1.0,"ipfs_cid":null,"license_hash":null}],"status":"testnet","staked_pwm":0.0,"chain_hash":"0x04d1d395d338d40f815b99d087248bcfd8137135379330a62c970ebe3addb5ac","chain_tx_hash":"0x7108982bdb302508fca241c067411799873d84e30a153268af2d480ce8a17d7f","chain_block":41553372}