The arrangement of parts in an object or organism.
M.E., from L. structura "a fitting together, adjustment, building," from structus, p.p. of struere "to pile, build, assemble," related to strues "heap," from PIE *stere- "to spread, extend, stretch out;" cf. Pers. gostar-, gostardan "to spread;" Av. star- "to spread," starati "spreads;" Skt. star- "to spread out, extend, strew," strnati "spreads;" Gk. stornumi "I spread out," strotos "spread, laid out;" Ger. Strahlung "radiation," from strahlen "to radiate," from Strahl "ray;" from M.H.G. strāle; from O.H.G. strāla "arrow, stripe."
Sâxtâr, from sâxt "made; make, construction, structure; style," past stem of sâxtan, sâzidan "to build, make, fashion; to adapt, adjust, be fit" (Mid.Pers. sâxtan, sâz-, Manichean Parthian s'c'dn "to prepare, to form;" Av. sak- "to understand, to mark," sâcaya- (causative) "to teach") + -âr verbal noun suffix.
Fr.: formation des structures
The study of the processes that gave rise to the apparition of matter concentrations,
such as → superclusters of galaxies,
→ galaxy clusters, and galaxies, in a homogeneous
→ expanding Universe.
Cosmic structures are believed to result from → density fluctuations
that existed in the → early Universe
before radiation and matter decoupled (→ decoupling era
or → recombination era). Initial
→ quantum fluctuations in the → inflaton field
were expanded by → inflation. Inflation amplified
them up to scales that correspond to those of galaxy clusters and beyond.
Generally, a model of structure formation includes three main ingredients: 1) background
cosmology, 2) model for fluctuation generation, and 3) types of
→ dark matter.
top-down structure formation
diseš-e sâxtâr az bâlâ bé pâyin
Fr.: formation des structures du haut vers le bas
A cosmological model of → structure formation in which larger structures, such as galaxy → superclusters or perhaps even the vast → filaments and → voids, form earlier and then they fragment into smaller structures such as individual galaxies. Opposite of → bottom-up structure formation.
Fr.: structure en arborescence
A type of → data structure in which each element is attached to one or more elements in a hierarchical manner. Trees are often called inverted trees because they are normally drawn with the root at the top.