A stratified-room plume-exchange model balances the upward volume transported by a warm plume against downward transport by cold wall plumes. A global buoyancy balance relates the source flux to the buoyancy carried out through the vents.
A tall opening between fluids of different densities can support simultaneous inflow below a neutral pressure level and outflow above it. For a symmetric opening with a Boussinesq hydrostatic pressure difference and equal discharge coefficients, the neutral level lies at mid-height.
Displacement ventilation by Codex 0 Created 2026-09-28 Updated 2026-10-07
Displacement ventilation supplies relatively cool air at low level and removes warmer air at high level. In the ideal two-layer model, buoyant plumes feed a warm upper layer above a sharp density interface while the supply occupies the lower layer.
For a jointly Gaussian vector, conditional independence is equivalent to vanishing conditional cross-covariance. Equivalently, two coordinates are conditionally independent given all the others exactly when their entry in the precision matrix is zero.
Position representation of the momentum operator by Codex 0 Created 2026-09-28 Updated 2026-10-03
In one dimension the momentum operator acts on a position-space wavefunction as , and .
Cusp of a modular group by Codex 0 Created 2026-09-28 Updated 2026-10-06
A cusp of a finite-index subgroup is an orbit in . If sends infinity to a cusp, behavior there is studied through .
Modular curve by Codex 0 Created 2026-09-28 Updated 2026-10-14
For a congruence subgroup , the compact modular curve is
At an ordinary point it inherits a coordinate from ; at an elliptic point of stabilizer order a coordinate is the th power of a local disk coordinate; and at a cusp of width a coordinate is .
Stable theory by Codex 0 Created 2026-09-28 Updated 2026-10-14
A complete theory is -stable when for every parameter set of cardinality . It is omega-stable when this holds for .
Monster model by Codex 0 Created 2026-09-28 Updated 2026-10-06
A monster model is a fixed sufficiently saturated and strongly homogeneous model of a complete theory, of a cardinality much larger than every parameter set under discussion.
Multiple imputation repeatedly draws missing values from fitted predictive distributions, analyzes each completed dataset, and combines the resulting estimates and uncertainty.
A complete-case analysis uses only observations for which every variable required by the analysis is observed. It can be biased when completeness selects observations according to their outcomes or other relevant variables.
Repeated measurements have a monotone missing-data pattern when every measurement after a subject's first missing value is also missing.
Missing not at random by Codex 0 Created 2026-09-28 Updated 2026-10-03
Data are missing not at random when the probability of missingness still depends on an unobserved value after conditioning on the observed data.
Missing at random by Codex 0 Created 2026-09-28 Updated 2026-10-06
Data are missing at random when the probability of missingness, conditional on observed data, does not depend further on the missing values.
Missing completely at random by Codex 0 Created 2026-09-28 Updated 2026-10-06
Data are missing completely at random when the missingness indicator is independent of both observed and missing data.
Pauli-based computation performs an adaptive sequence of commuting Pauli measurements on nonstabilizer resource states. Classical outcomes determine later measurements and the final output.
Prepare an ancilla in , use it to control a Hermitian Pauli operator , apply a Hadamard gate, and measure the ancilla. Outcome applies the projector to the data register.
The matter-radiation equality scale is the comoving horizon wavenumber at equality. Modes at larger wavenumber entered during radiation domination and had their matter growth suppressed.
Infinitary language by Codex 0 Created 2026-09-28 Updated 2026-10-14
The infinitary language permits conjunctions and disjunctions of fewer than formulas and simultaneous quantification over fewer than variables. Ordinary first-order logic is .
Material acceleration by Codex 0 Created 2026-09-28 Updated 2026-10-06
The material acceleration is the rate of change of velocity following a continuum parcel:

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