{"bundle_type":"pith_open_graph_bundle","bundle_version":"1.0","pith_number":"pith:2014:ISM3UBH6BTFNPJJF5HWYSD4AQA","short_pith_number":"pith:ISM3UBH6","canonical_record":{"source":{"id":"1408.1807","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2014-08-08T10:21:14Z","cross_cats_sorted":[],"title_canon_sha256":"6a8c1f8e1d4bc45169926e7a4466ea7b931b9fb0a5dc612aa46f9ae67ab8a735","abstract_canon_sha256":"b252a16654d7180d4cd04fd26cfb53a40a4a34a6721fd633eac159c5df107578"},"schema_version":"1.0"},"canonical_sha256":"4499ba04fe0ccad7a525e9ed890f808002301539075b413bda4c1e186804b136","source":{"kind":"arxiv","id":"1408.1807","version":1},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1408.1807","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"arxiv_version","alias_value":"1408.1807v1","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1408.1807","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"pith_short_12","alias_value":"ISM3UBH6BTFN","created_at":"2026-05-18T12:28:33Z"},{"alias_kind":"pith_short_16","alias_value":"ISM3UBH6BTFNPJJF","created_at":"2026-05-18T12:28:33Z"},{"alias_kind":"pith_short_8","alias_value":"ISM3UBH6","created_at":"2026-05-18T12:28:33Z"}],"events":[{"event_type":"record_created","subject_pith_number":"pith:2014:ISM3UBH6BTFNPJJF5HWYSD4AQA","target":"record","payload":{"canonical_record":{"source":{"id":"1408.1807","kind":"arxiv","version":1},"metadata":{"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2014-08-08T10:21:14Z","cross_cats_sorted":[],"title_canon_sha256":"6a8c1f8e1d4bc45169926e7a4466ea7b931b9fb0a5dc612aa46f9ae67ab8a735","abstract_canon_sha256":"b252a16654d7180d4cd04fd26cfb53a40a4a34a6721fd633eac159c5df107578"},"schema_version":"1.0"},"canonical_sha256":"4499ba04fe0ccad7a525e9ed890f808002301539075b413bda4c1e186804b136","receipt":{"kind":"pith_receipt","key_id":"pith-v1-2026-05","algorithm":"ed25519","signed_at":"2026-05-18T01:42:22.618408Z","signature_b64":"YNR1klsNC7S0aepgTLaJEXhNOE5Zr61qlKBN33pw/tyg+uRNsn9rNltgrd6fwXm7z/TJVcA3KHT5MGy1d8Q1Bg==","signed_message":"canonical_sha256_bytes","builder_version":"pith-number-builder-2026-05-17-v1","receipt_version":"0.3","canonical_sha256":"4499ba04fe0ccad7a525e9ed890f808002301539075b413bda4c1e186804b136","last_reissued_at":"2026-05-18T01:42:22.617873Z","signature_status":"signed_v1","first_computed_at":"2026-05-18T01:42:22.617873Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"source_kind":"arxiv","source_id":"1408.1807","source_version":1,"attestation_state":"computed"},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:42:22Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"ZkI5TD6fTMoawwvxkRO5udsuVRyppOP4rUSFxs9BrQM+KfpfJIsZf30I4WR5hlX8mUymdf1krniaDNs133dPBw==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-17T12:35:40.777143Z"},"content_sha256":"82de21ad461a27ed775405128bca2221eb1c97c66ae32486ea69053fd15d001e","schema_version":"1.0","event_id":"sha256:82de21ad461a27ed775405128bca2221eb1c97c66ae32486ea69053fd15d001e"},{"event_type":"graph_snapshot","subject_pith_number":"pith:2014:ISM3UBH6BTFNPJJF5HWYSD4AQA","target":"graph","payload":{"graph_snapshot":{"paper":{"title":"Ambipolar diffusion in smoothed particle magnetohydrodynamics","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","headline":"","cross_cats":[],"primary_cat":"astro-ph.SR","authors_text":"Ben A. Ayliffe, Daniel J. Price, James Wurster","submitted_at":"2014-08-08T10:21:14Z","abstract_excerpt":"In partially ionised plasmas, the magnetic field can become decoupled from the neutral gas and diffuse through it in a process known as ambipolar diffusion. Although ambipolar diffusion has been implemented in several grid codes, we here provide an implementation in smoothed particle magnetohydrodynamics (SPMHD). We use the strong coupling approximation in which the ion density is negligible, allowing a single fluid approach. The equations are derived to conserve energy, and to provide a positive definite contribution to the entropy. We test the implementation in both a simple 1D SPMHD code an"},"claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1408.1807","kind":"arxiv","version":1},"verdict":{"id":null,"model_set":{},"created_at":null,"strongest_claim":"","one_line_summary":"","pipeline_version":null,"weakest_assumption":"","pith_extraction_headline":""},"references":{"count":0,"sample":[],"resolved_work":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","internal_anchors":0},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"author_claims":{"count":0,"strong_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"builder_version":"pith-number-builder-2026-05-17-v1"},"verdict_id":null},"signer":{"signer_id":"pith.science","signer_type":"pith_registry","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54"},"created_at":"2026-05-18T01:42:22Z","supersedes":[],"prev_event":null,"signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"KAgv6TABrI4+e4IUBawUN/vtr73Cbbye/DRQM9Byp7NRAXHbsIiVoTYuU0JJAKJK5BRsnH0LlJEJp5LVlB3lCA==","signed_message":"open_graph_event_sha256_bytes","signed_at":"2026-08-17T12:35:40.777871Z"},"content_sha256":"e09bd273e2e24b24f0b0cf7e6c85b8c64e53445bd6355d034a5e0691e2e6d052","schema_version":"1.0","event_id":"sha256:e09bd273e2e24b24f0b0cf7e6c85b8c64e53445bd6355d034a5e0691e2e6d052"}],"timestamp_proofs":[],"mirror_hints":[{"mirror_type":"https","name":"Pith Resolver","base_url":"https://pith.science","bundle_url":"https://pith.science/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/bundle.json","state_url":"https://pith.science/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/state.json","well_known_bundle_url":"https://pith.science/.well-known/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/bundle.json","status":"primary"}],"public_keys":[{"key_id":"pith-v1-2026-05","algorithm":"ed25519","format":"raw","public_key_b64":"stVStoiQhXFxp4s2pdzPNoqVNBMojDU/fJ2db5S3CbM=","public_key_hex":"b2d552b68890857171a78b36a5dccf368a953413288c353f7c9d9d6f94b709b3","fingerprint_sha256_b32_first128bits":"RVFV5Z2OI2J3ZUO7ERDEBCYNKS","fingerprint_sha256_hex":"8d4b5ee74e4693bcd1df2446408b0d54","rotates_at":null,"url":"https://pith.science/pith-signing-key.json","notes":"Pith uses this Ed25519 key to sign canonical record SHA-256 digests. Verify with: ed25519_verify(public_key, message=canonical_sha256_bytes, signature=base64decode(signature_b64))."}],"merge_version":"pith-open-graph-merge-v1","built_at":"2026-08-17T12:35:40Z","links":{"resolver":"https://pith.science/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA","bundle":"https://pith.science/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/bundle.json","state":"https://pith.science/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/state.json","well_known_bundle":"https://pith.science/.well-known/pith/ISM3UBH6BTFNPJJF5HWYSD4AQA/bundle.json"},"state":{"state_type":"pith_open_graph_state","state_version":"1.0","pith_number":"pith:2014:ISM3UBH6BTFNPJJF5HWYSD4AQA","merge_version":"pith-open-graph-merge-v1","event_count":2,"valid_event_count":2,"invalid_event_count":0,"equivocation_count":0,"current":{"canonical_record":{"metadata":{"abstract_canon_sha256":"b252a16654d7180d4cd04fd26cfb53a40a4a34a6721fd633eac159c5df107578","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2014-08-08T10:21:14Z","title_canon_sha256":"6a8c1f8e1d4bc45169926e7a4466ea7b931b9fb0a5dc612aa46f9ae67ab8a735"},"schema_version":"1.0","source":{"id":"1408.1807","kind":"arxiv","version":1}},"source_aliases":[{"alias_kind":"arxiv","alias_value":"1408.1807","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"arxiv_version","alias_value":"1408.1807v1","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"doi","alias_value":"10.48550/arxiv.1408.1807","created_at":"2026-05-18T01:42:22Z"},{"alias_kind":"pith_short_12","alias_value":"ISM3UBH6BTFN","created_at":"2026-05-18T12:28:33Z"},{"alias_kind":"pith_short_16","alias_value":"ISM3UBH6BTFNPJJF","created_at":"2026-05-18T12:28:33Z"},{"alias_kind":"pith_short_8","alias_value":"ISM3UBH6","created_at":"2026-05-18T12:28:33Z"}],"graph_snapshots":[{"event_id":"sha256:e09bd273e2e24b24f0b0cf7e6c85b8c64e53445bd6355d034a5e0691e2e6d052","target":"graph","created_at":"2026-05-18T01:42:22Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"graph_snapshot":{"author_claims":{"count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57","strong_count":0},"builder_version":"pith-number-builder-2026-05-17-v1","claims":{"count":0,"items":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"formal_canon":{"evidence_count":0,"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"paper":{"abstract_excerpt":"In partially ionised plasmas, the magnetic field can become decoupled from the neutral gas and diffuse through it in a process known as ambipolar diffusion. Although ambipolar diffusion has been implemented in several grid codes, we here provide an implementation in smoothed particle magnetohydrodynamics (SPMHD). We use the strong coupling approximation in which the ion density is negligible, allowing a single fluid approach. The equations are derived to conserve energy, and to provide a positive definite contribution to the entropy. We test the implementation in both a simple 1D SPMHD code an","authors_text":"Ben A. Ayliffe, Daniel J. Price, James Wurster","cross_cats":[],"headline":"","license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2014-08-08T10:21:14Z","title":"Ambipolar diffusion in smoothed particle magnetohydrodynamics"},"references":{"count":0,"internal_anchors":0,"resolved_work":0,"sample":[],"snapshot_sha256":"258153158e38e3291e3d48162225fcdb2d5a3ed65a07baac614ab91432fd4f57"},"source":{"id":"1408.1807","kind":"arxiv","version":1},"verdict":{"created_at":null,"id":null,"model_set":{},"one_line_summary":"","pipeline_version":null,"pith_extraction_headline":"","strongest_claim":"","weakest_assumption":""}},"verdict_id":null}}],"author_attestations":[],"timestamp_anchors":[],"storage_attestations":[],"citation_signatures":[],"replication_records":[],"corrections":[],"mirror_hints":[],"record_created":{"event_id":"sha256:82de21ad461a27ed775405128bca2221eb1c97c66ae32486ea69053fd15d001e","target":"record","created_at":"2026-05-18T01:42:22Z","signer":{"key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signer_id":"pith.science","signer_type":"pith_registry"},"payload":{"attestation_state":"computed","canonical_record":{"metadata":{"abstract_canon_sha256":"b252a16654d7180d4cd04fd26cfb53a40a4a34a6721fd633eac159c5df107578","cross_cats_sorted":[],"license":"http://arxiv.org/licenses/nonexclusive-distrib/1.0/","primary_cat":"astro-ph.SR","submitted_at":"2014-08-08T10:21:14Z","title_canon_sha256":"6a8c1f8e1d4bc45169926e7a4466ea7b931b9fb0a5dc612aa46f9ae67ab8a735"},"schema_version":"1.0","source":{"id":"1408.1807","kind":"arxiv","version":1}},"canonical_sha256":"4499ba04fe0ccad7a525e9ed890f808002301539075b413bda4c1e186804b136","receipt":{"algorithm":"ed25519","builder_version":"pith-number-builder-2026-05-17-v1","canonical_sha256":"4499ba04fe0ccad7a525e9ed890f808002301539075b413bda4c1e186804b136","first_computed_at":"2026-05-18T01:42:22.617873Z","key_id":"pith-v1-2026-05","kind":"pith_receipt","last_reissued_at":"2026-05-18T01:42:22.617873Z","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","receipt_version":"0.3","signature_b64":"YNR1klsNC7S0aepgTLaJEXhNOE5Zr61qlKBN33pw/tyg+uRNsn9rNltgrd6fwXm7z/TJVcA3KHT5MGy1d8Q1Bg==","signature_status":"signed_v1","signed_at":"2026-05-18T01:42:22.618408Z","signed_message":"canonical_sha256_bytes"},"source_id":"1408.1807","source_kind":"arxiv","source_version":1}}},"equivocations":[],"invalid_events":[],"applied_event_ids":["sha256:82de21ad461a27ed775405128bca2221eb1c97c66ae32486ea69053fd15d001e","sha256:e09bd273e2e24b24f0b0cf7e6c85b8c64e53445bd6355d034a5e0691e2e6d052"],"state_sha256":"186b0a2d906b046ce5d27dedc4078a408dd97ec036393684d66181273a3087ae"},"bundle_signature":{"signature_status":"signed_v1","algorithm":"ed25519","key_id":"pith-v1-2026-05","public_key_fingerprint":"8d4b5ee74e4693bcd1df2446408b0d54","signature_b64":"4ULYCih+AEOf6dQCaMRzsIpJUR3kyGrdwLmRrauope7651V33c304JUOfKtNHYnk2+5QdfNSC1oZU5ORVSuwBg==","signed_message":"bundle_sha256_bytes","signed_at":"2026-08-17T12:35:40.786303Z","bundle_sha256":"e57bca4e613ebd9e02c125dbf2cec2a093281bbdc6868e7c914b59e0adb879f0"}}