All articles A–Z

Spectacle Entertainment

Spectacle Entertainment was a casino gaming company formed in 2018 by former Centaur Gaming executives to acquire the Majestic Star casino licenses in Gary, Indiana.

Spectacled bear (Tremarctos ornatus), also called Andean bear or Jukumari: the only bear in South America and last living tremarctine, found in Andes from Venezuela to Bolivia, IUCN Vulnerable, karyotype 2n=52.

Spectinomycin

Spectinomycin (Trobicin) is an aminocyclitol antibiotic produced by the bacterium Streptomyces spectabilis, isolated in 1960 and used as a single intramuscular 2 g dose to treat gonorrhea.

Spectral

Spectral (2016) is a military sci-fi action film directed by Nic Mathieu, starring James Badge Dale, about a Delta Force team fighting Bose-Einstein-condensate apparitions in Moldova; released as a Netflix exclusive on December 9, 2016.

Spectral acceleration

Spectral acceleration is an earthquake engineering measure of the maximum acceleration a damped oscillator with a given natural period experiences in ground motion, approximating what a building experiences.

Spectral action principle

The spectral action principle is a 1996 proposal in noncommutative geometry by Chamseddine and Connes that builds a space's action from the spectrum of its Dirac operator.

Spectral clustering

Spectral clustering is a graph-based clustering method that partitions data points using the eigenvectors of a Laplacian matrix built from a similarity graph, suited to non-convex clusters such as spirals.

Spectral collocation method

The spectral collocation method, also called the pseudospectral method, is a numerical technique for solving differential equations by representing the solution with global basis functions and enforcing the equation exactly at collocation points.

Spectral color

Spectral color: the color of monochromatic light, one wavelength of the visible spectrum. Newton's seven-color spectrum (originally five), Newton's color circle, and nonspectral colors like purple and magenta.

Spectral computed tomography

Spectral computed tomography is an X-ray imaging method that measures attenuation in separate energy ranges, producing iodine maps, virtual non-contrast images, and uric acid stone differentiation.

Spectral counting

Spectral counting is a label-free quantification method in shotgun proteomics that estimates relative protein abundance by counting identified tandem mass spectra, formalized in 2004 by Liu, Sadygov, and Yates.

Spectral CT

Spectral CT, including dual-energy CT and photon-counting CT, is computed tomography that acquires X-ray attenuation data at two or more energy levels, enabling material decomposition and tissue characterization.

Spectral decomposition (seismic)

Spectral decomposition in seismology is a family of time-frequency analysis methods that breaks a seismic trace into its frequency components, revealing bed thickness variations, discontinuities, and fluid effects.

Spectral density

The spectral density, or spectral power density, describes how the power or energy of a signal or random process is distributed over frequency, revealing oscillations and noise hidden in the time domain.

Spectral density estimation

Spectral density estimation is the set of statistical methods for estimating a time series' power spectral density, showing how its variance is distributed across frequency.

Spectral diffusion

Spectral diffusion is the random change over time of a spectral line's resonance frequency caused by environmental fluctuations, appearing as random spectral jumps in optical and spin resonance spectroscopy.

Spectral dimension

The spectral dimension is a scale-dependent measure of effective dimensionality, defined through diffusion; in quantum gravity it typically flows from 4 to 2 at small scales.

Spectral element method

The spectral element method is a numerical technique for solving partial differential equations, combining high-order polynomial basis functions with a finite-element mesh for exponential convergence.

Spectral embedding

Spectral embedding is a family of nonlinear dimensionality reduction methods that represent data points or graph nodes in low-dimensional space using eigenvectors of a graph Laplacian built from pairwise similarities.

Spectral fingerprinting

Spectral fingerprinting is an analytical chemistry method that identifies a substance by matching its infrared, Raman, terahertz, NMR, or mass spectrum against reference spectra, yielding a match score rather than a quantitative composition.

Spectral flow cytometry

Spectral flow cytometry is a single-cell analysis technique that measures the full fluorescence spectrum of each cell, separating dyes by spectral unmixing in panels of up to 50 colors.

Spectral gap (Markov chain)

The spectral gap of a Markov chain, for a reversible chain equal to 1 minus the second-largest eigenvalue, measures how fast the chain converges to its stationary distribution.

Spectral graph theory

Spectral graph theory is the branch of graph theory that studies graphs through eigenvalues and eigenvectors of their adjacency, degree, and Laplacian matrices, linking algebra to properties like connectivity.

Spectral hole burning

Spectral hole burning is a spectroscopy technique in which a narrow-band laser bleaches a dip into an inhomogeneously broadened absorption line, resolving features 1,000 to 100,000 times finer than conventional methods.

Spectral index (cosmology)

The scalar spectral index, ns, is the exponent describing how the amplitude of primordial density fluctuations depends on scale, measured near 0.965 and seen as key evidence for cosmic inflation.

Spectral interferometry

Spectral interferometry is an optical measurement technique that records the interference spectrum of two light beams, retrieving spectral phase to measure distance, film thickness, and dispersion.

Spectral karyotyping

Spectral karyotyping (SKY) is a cytogenetic technique that paints all 24 human chromosomes in distinct colors in one experiment, revealing translocations and complex rearrangements invisible to banding analysis.

Spectral kurtosis

Spectral kurtosis is a statistical signal-processing measure that shows how a signal's impulsiveness varies across frequency bands, used chiefly to select demodulation bands for bearing and gear fault diagnosis.

Spectral library search

Spectral library search is a proteomics method that identifies peptides by matching experimental MS/MS spectra against a reference library, hundreds of times faster than sequence database search.