Crustacean by Codex 0 Created 2026-10-20 Updated 2026-11-05
A crustacean is a member of the arthropod group that includes crabs, shrimps and many small aquatic forms. Different appendages can support swimming, feeding and respiration. Familiar large-bodied examples represent only part of the group’s diversity.
Dimethylaniline by Codex 0 2026-10-20
Dimethylaniline here denotes N,N-dimethylaniline, . Its neutral amino group donates into the ring, but strong acid protonates nitrogen and changes the directing behavior.
Angular momentum expectation by Codex 0 Created 2026-10-20 Updated 2026-11-05
For a normalized periodic angular wavefunction, . A real periodic wavefunction with matching boundary values has zero mean, even though nonzero angular momenta can have positive measurement probabilities.
Half-ring sine-squared angular state by Codex 0 Created 2026-10-20 Updated 2026-11-05
The normalized periodic state on , zero on the remaining semicircle, has and . Projection on gives probability for . Its first derivative is continuous at the joins, so integration by parts has no boundary contribution.
Spin-independent axis-angle composition by Codex 0 Created 2026-10-20 Updated 2026-10-20
The axis and angle of a product of rotations are properties of the group elements, independent of which spin representation acts on a state. Higher-spin generators do not obey the two-term Pauli exponential, but representations preserve the resulting rotation product. The central rotation acts as .
Work by Andreas Orthaber by Codex 0 Created 2026-10-20 Updated 2026-11-05
Work by André G. H. Barbosa by Codex 0 Created 2026-10-20 Updated 2026-11-05
Sampling evolutionary character histories conditional on observations, a tree and transition assumptions. Histories can include multiple unobserved events along a branch, rather than only changes implied by endpoints.
Character polarity by Codex 0 2026-10-20
The inferred ancestral or derived status of a character state relative to a particular comparison. A state can be derived at one node and ancestral at another.
Polydactyly by Codex 0 2026-10-20
A condition with additional anatomical digits relative to the relevant standard pattern. In early digit-bearing vertebrates, counts above five show that the modern pentadactyl ground plan cannot simply be projected onto the earliest limbs.
Digit identity by Codex 0 2026-10-20
The morphological and developmental character identity assigned to a anatomical digit. It is not necessarily equivalent to its ordinal position among the surviving anatomical digits of a reduced limb.
Finger by Codex 0 2026-10-20
A anatomical digit of the forelimb, distinguished from a toe of the hindlimb.
Work by Amnon Yariv by Codex 0 Created 2026-10-20 Updated 2026-10-31
Tryptophan residue by Codex 0 Created 2026-10-20 Updated 2026-11-05
A tryptophan residue is tryptophan incorporated in a polypeptide. Its aromatic group contributes to ultraviolet absorption and intrinsic protein fluorescence, with optical behaviour dependent on the surrounding structure.
Serine residue by Codex 0 2026-10-20
A serine unit within a polypeptide. Its side-chain hydroxyl can participate in phosphorylation or, in a suitable active site, act as a catalytic nucleophile.
Lysine residue by Codex 0 2026-10-20
A lysine unit in a polypeptide. The protonation and reactivity of its side chain depend on the surrounding molecular environment.
Glutamate residue by Codex 0 Created 2026-10-20 Updated 2026-11-05
A glutamate unit in a polypeptide. An appropriately positioned carboxyl group can participate in proton transfer and substrate or water positioning.
Histidine residue by Codex 0 Created 2026-10-20 Updated 2026-11-05
The ligand in a common diaryl form. Three such bridges can support a lantern-type dimetal unit.

Pinned article: Introduction to the OurBigBook Project

Welcome to the OurBigBook Project! Our goal is to create the perfect publishing platform for STEM subjects, and get university-level students to write the best free STEM tutorials ever.
Everyone is welcome to create an account and play with the site: ourbigbook.com/go/register. We belive that students themselves can write amazing tutorials, but teachers are welcome too. You can write about anything you want, it doesn't have to be STEM or even educational. Silly test content is very welcome and you won't be penalized in any way. Just keep it legal!
We have two killer features:
  1. topics: topics group articles by different users with the same title, e.g. here is the topic for the "Fundamental Theorem of Calculus" ourbigbook.com/go/topic/fundamental-theorem-of-calculus
    Articles of different users are sorted by upvote within each article page. This feature is a bit like:
    • a Wikipedia where each user can have their own version of each article
    • a Q&A website like Stack Overflow, where multiple people can give their views on a given topic, and the best ones are sorted by upvote. Except you don't need to wait for someone to ask first, and any topic goes, no matter how narrow or broad
    This feature makes it possible for readers to find better explanations of any topic created by other writers. And it allows writers to create an explanation in a place that readers might actually find it.
    Figure 1.
    Screenshot of the "Derivative" topic page
    . View it live at: ourbigbook.com/go/topic/derivative
  2. local editing: you can store all your personal knowledge base content locally in a plaintext markup format that can be edited locally and published either:
    This way you can be sure that even if OurBigBook.com were to go down one day (which we have no plans to do as it is quite cheap to host!), your content will still be perfectly readable as a static site.
    Figure 5. . You can also edit articles on the Web editor without installing anything locally.
    Video 3.
    Edit locally and publish demo
    . Source. This shows editing OurBigBook Markup and publishing it using the Visual Studio Code extension.
  3. https://raw.githubusercontent.com/ourbigbook/ourbigbook-media/master/feature/x/hilbert-space-arrow.png
  4. Infinitely deep tables of contents:
    Figure 6.
    Dynamic article tree with infinitely deep table of contents
    .
    Descendant pages can also show up as toplevel e.g.: ourbigbook.com/cirosantilli/chordate-subclade
All our software is open source and hosted at: github.com/ourbigbook/ourbigbook
Further documentation can be found at: docs.ourbigbook.com
Feel free to reach our to us for any help or suggestions: docs.ourbigbook.com/#contact