GLOBAL KNOWLEDGE ARK

Reference library

Foundations

Explore concepts, laws, equations and methods, with clear explanations of their use and sources. Choose an area of study or find a specific entry.

More filters

Reference entries

Showing 1471–1500 of 1709 reference entries

Earth & cosmosCoupled photoionization, cooling and planetary escape

A photoheated atmosphere couples fluid transport, ionization/recombination, absorption and radiative cooling.

Method
Earth & cosmosCosmological continuity and constant-w density scaling

For an independently conserved homogeneous component with constant equation-of-state w, density scales with a as a^-3(1+w).

Method
Earth & cosmosMatter, radiation and vacuum expansion solutions

Combining a conserved component with flat single-component Friedmann expansion yields matter a∝t^(2/3), radiation a∝t^(1/2) and vacuum exponential expansion.

Method
Earth & cosmosJoint cosmological likelihoods and nuisance degeneracies

Cosmological parameter inference combines data likelihoods with model priors and nuisance parameters for foregrounds, calibration and selection.

Method
Earth & cosmos2026 preprint: DESI Lyman-alpha geometry and dark-energy inference

DESI DR2 Lyman-alpha Alcock–Paczyński measurements add redshift-dependent geometry information with blinded validation and contaminant controls.

Method
Earth & cosmosDeclared isotope reaction networks and stiff abundance balance

A reaction network lists its species and reactions, evolves abundances with a stoichiometric matrix and couples nuclear energy release and escaping neutrino losses to stellar energy.

Method
Earth & cosmosCross-section, resonance and screening uncertainty

Thermal rates average microscopic cross sections over a specified particle distribution.

Method
Earth & cosmosCore-collapse neutrino transport and closure

Core-collapse models couple dense-matter EOS, fluid motion and flavor/energy-dependent neutrino radiation.

Method
Earth & cosmosCompact-star EOS inference across messengers

Dense-matter inference combines nuclear constraints, pulse-profile models and gravitational-wave likelihoods with an EOS parameterization.

Method
Earth & cosmosGRMHD conservation and declared boundary data

Ideal GRMHD evolves rest-mass and stress-energy conservation with magnetic induction in a specified spacetime.

Method
Earth & cosmosMagnetorotational transport and magnetic-flux dependence

Weak well-coupled magnetic fields can destabilize outwardly decreasing differential rotation and drive angular-momentum transport.

Method
Earth & cosmosKinetic reconnection and particle-population limits

Particle-in-cell reconnection experiments evolve fields and particle distributions rather than assume a thermal fluid closure.

Method
Earth & cosmosPolarized synchrotron and self-absorption

For isotropic power-law electrons in a uniform field, optically thin synchrotron has a conditional spectral slope and maximum linear polarization.

Method
Earth & cosmosInverse Compton angular kernels and Klein–Nishina regime

Inverse Compton energy gain depends on incident angle and the photon energy in the electron rest frame.

Method
Earth & cosmosPhoton-pair threshold, opacity and cascades

Two photons can produce an electron–positron pair only above an angle-dependent invariant threshold.

Method
Earth & cosmosCollisionless N-body force and resolution tests

A particle realization approximates a smooth collisionless distribution; force softening and time integration control numerical encounters and force error.

Method
Earth & cosmosGalaxy gas dynamics and matched-solver comparisons

Finite-volume hydrodynamics updates conserved quantities using fluxes across cell boundaries; moving faces require fluxes in the face frame.

Method
Earth & cosmosBar and spiral orbital resonances

Rotating nonaxisymmetric potentials exchange angular momentum at corotation and Lindblad resonances.

Method
Earth & cosmosElement-resolved delayed recycling and gas flows

Chemical evolution follows an element's removal into stars, delayed stellar returns and inflow/outflow.

Method
Earth & cosmosFeedback calibration and survey selection

Unresolved star formation, cooling and feedback need declared subgrid closures and calibrated parameter ranges.

Method
Earth & cosmosPerturbed metric, gauge and physical observables

Relativistic perturbation variables depend on the coordinate gauge.

Method
Earth & cosmosEinstein–Boltzmann hierarchy and convergence

Angular moments of photon/neutrino distributions form a Boltzmann hierarchy coupled to metric and fluid equations.

Method
Earth & cosmosPrimordial models, scalar spectra and tensor tests

Inflationary models relate a stated field action and reheating history to scalar/tensor predictions; observations constrain those predictions rather than identify one unique inflaton.

Method
Earth & cosmosOpen question: unique primordial mechanism

A unique microscopic origin of primordial perturbations is not established by the inspected evidence.

Open question
Earth & cosmosDark-matter evidence and candidate tests

Gravitational evidence constrains additional matter or modified gravitational descriptions under declared assumptions; it does not name a particle.

Method
Earth & cosmosOpen question: dark-matter identity

The dominant dark-matter identity remains unresolved in the inspected evidence.

Open question
Earth & cosmosCosmic acceleration: Λ, dynamical fields and modified gravity

Acceleration is inferred through a framework relating expansion and structure to observations.

Method
Earth & cosmosOpen question: physical cause of acceleration

The physical cause of cosmic acceleration remains unresolved in the inspected sources.

Open question
Earth & cosmosLinear poroelastic storage and deformation coupling

A quasi-static poroelastic model couples elastic displacement to pore pressure and fluid storage.

Method
Earth & cosmosElectromagnetic parameter maps and primary-secondary sensitivities

EM inversion links conductivity/permeability parameters to source, fields and receiver response.

Method
MethodSource checked

Declared isotope reaction networks and stiff abundance balance

Earth & cosmos

Research context

research method · conditional · As of 2026-10-10

A reaction network lists its species and reactions, evolves abundances with a stoichiometric matrix and couples nuclear energy release and escaping neutrino losses to stellar energy.

Key knowledge

A reaction network lists its species and reactions, evolves abundances with a stoichiometric matrix and couples nuclear energy release and escaping neutrino losses to stellar energy. Complete means complete for that declared model; reduced effective networks must not be presented as every physical pathway.

Values and equations

dY_i/dt=sum_r N_ir R_r(Y,T,ρ); sum_i A_i Y_i=1

Y_i
Number of nuclei i per baryon 1
N_ir
Signed reaction stoichiometry for species i 1
R_r
Reaction events per baryon per time s^-1
A_i
Mass number 1
T
Temperature K
ρ
Mass density kg m^-3

Conditions and scope

  • Specify abundance normalization, inverse/weak rates, screening and charge/baryon accounting; weak reactions can change charge fraction.
  • Check positivity, nucleon balance and independent step/network convergence; Jacobian-based implicit integration addresses stiffness.
  • Baryon-normalized convention; sum rule includes every free/bound nucleon species and ignores tiny binding corrections in the mass-density conversion.
Sources · 2

References

Sources retain their recorded scope. A source link alone does not establish verification of every statement.

  1. Nuclear astrophysics: reaction networksFrank Timmes; NNPSS (2009)Reference guide · PDFcococubed.comRead source
  2. MESA reaction networksMESA teamReference guidedocs.mesastar.orgRead source

Evidence and review

Nuclear astrophysics: reaction networks: Abundance derivatives, reaction stoichiometry, energy generation and stiff integration (selected source body inspected). MESA reaction networks: Network definitions, explicit reaction listing and advanced-burning limitations (selected source body inspected).

2026-10-10 · Bounded source check of the recorded statement and conditions. This does not certify a unique physical model, reproduce the cited study or replace independent branch review.

Entry detailsPermanent link to this entry ↗
Record identity
research-earth-nuclear-network
Revision
research.1
Structured reference record
Postgraduate & research reference