SubstrateCommons/cactus-axons

Replay packs (.rpk) built with dmipy_sim: one converged Monte-Carlo walk each, stored so any acquisition can be replayed on it. Load one with ReplayPack.load("hf://SubstrateCommons/cactus-axons/<path>"); the manifest (manifest.json) holds the sha256 every load is checked against. This file is rendered from the manifest by dmipy_sim.replay.publish.

Substrate

cactus/cactus_bundle_00000

• box: 30 × 30 × 30 µm
• boundary: periodic, periodic, periodic

pool	D (m²/s)	water fraction
extra	1.7e-09	1
intra	1.7e-09	1
myelin	0	0.4

Packs

id	duration	walkers	bands	channels	floor	size	commit	path
cactus/single-bundle-1s-c3-seg125ms	1000 ms (8 × 125 ms, 472.0 MB/window)	100000	320	positions, boundary_local_time, compartment, susceptibility_grid, susceptibility_path	0.0266	3.8 GB	e8c640e4	packs/single_bundle_1s_c3_seg125ms.rpk

Citation

• Villarreal-Haro et al., CACTUS; dmipy-sim#285, #528

The single-bundle 1 s walk in 125 ms windows (cactus/single-bundle-1s-c3-seg125ms)

packs/single_bundle_1s_c3_seg125ms.rpk: the CACTUS single-bundle walk of 1 s (100,000 walkers in five shards, 13,017 saves at 76.83 µs, D 1.7e-9 m²/s, C1 + C2 + C3) stored as 8 windows of 1,628 saves (125.0 ms) sharing their boundary saves (RPK.md §4.3), built from the kept raw walks (bank._build_segmented): every window a pack of its own from the walk's saves of that window, positions at K 320 per window (1280 Hz), the contact channel the window's own cumulative local time at K 8 per window, the C3 path channel at K 64 per window. A consumer reads only the windows an acquisition reaches: ReplayPack.load("hf://SubstrateCommons/cactus-axons/packs/single_bundle_1s_c3_seg125ms.rpk", windows=range(k)) fetches the header and the byte ranges of windows 0..k-1 (segment_bytes in the manifest row says what one window costs); every class up to 125 ms reads window 0, up to 250 ms two.

Certificate. Shard 1 measured every window against its raw walk (fidelity.segments[i]: path-tier error 5.6e-3 to 7.9e-3 against floors 1.0e-2 to 2.7e-2, surface error 1e-11, positions over the whole walk), shards 2-5 inherited window by window (dmipy-sim#535); the whole's err_max 5.1e-2 is the sum of the eight windows' path errors (the additive bound of combine_segment_fidelity) against floor_max 2.7e-2. Measured equality with the one-window parent cactus/swoop-1s-c3 on the same waveforms (max |ΔS|, 61 measurements at b 1000 and 3000, the pack's spec at 3 T): PGSE TE 100 ms (one window) bare 3.8e-8, relaxation 9.4e-9, contact 1.0e-4, field 1.0e-4, all tiers 2.3e-5; PGSE TE 160 ms and PGSTE TE 184 ms (two windows) bare ≤ 3.4e-7, all tiers ≤ 7.0e-5.

Contact tier. Each window's contact is its own, so the pack states no contact envelope: at ρ/D 5,882 and 11,765 1/m (ρ 1e-5 and 2e-5 m/s) it agrees with its one-window parent to 1.8e-4 and 3.2e-5, and its attenuation stays in (0, 1]. The spec declares the myelin pool's susceptibility, so the field tier reads the stored field channel.