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from article Branched polymer
Steps in the synthesis of a starburst polymer. s = surface. o = interior. fr = reactive group. fp = protected group.
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from article Tangent
Line L tangent to curve C at P.
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from article Civet
Owston's palm civet (Chrotogale owston). (Photo copyright © by Mark Kostich)
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from article Heterocyclic polymer
Structural units in linear polymers. (a) Simple linear polymer. (b) Stepladder polymer. (c) Ladder polymer.
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from article Heterocyclic polymer
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from article Patellogastropoda
Whitecap limpet (Acmaea mitra). (Photo by Douglas Eernisse)
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from article Patellogastropoda
Ribbed Mediterranean limpet (Patella ferruginea). (Photo by Georgina Rivera Ingraham)
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from article Patellogastropoda
Radula of the patellogastropod Notoacmea scapha.
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from article Intermolecular forces
Schematic diagram of intermolecular interaction. (a) There is negligible interaction between atoms that are 1 nm apart. (b) For atoms separated by about 0.8 nm or less, attractive dispersion forces result from correlated fluctuations of the electron…
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from article Bicosoecida
A bicosoecid, Codomonas annulata.
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from article Rhizocephala
Loxothylacus texanus (arrow) attached to the abdomen of the blue crab (Callinectes sapidus). (After E. G. Reinhard, Parasitic castration of Callinectes, Exp. Parasitol., 5:79–107, 1956)
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from article Negative refraction
Refraction: Diagrams of (a) positive refraction and (b) negative refraction; and calculated images of a metal rod (c) in a glass filled with regular water (n = 1.3), and (d) in a glass filled with “ negative-index water ” (n = −1.3). In parts a and…
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from article Negative refraction
Schematics of (a) superlens, (b) hyperlens, and (c) imaging system using a hyperlens. In parts a and b, solid lines correspond to the propagating field components, broken lines correspond to the evanescent field components.
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from article Negative refraction
Cloaking. (a) The transformation of a cylindrical region r < b into a concentric cylindrical shell a < r < b and an enlarged section of a nonmagnetic optical cloak built with metal wires embedded in a dielectric host. (b) Numerical simulations of an…
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from article Masking of sound
Three psychophysical tuning curves, showing the tonal masking effects for tonal signals of 300, 1000, or 3000 Hz. (After F. L. Wightman et al. Factors influencing frequency selectivity in normal and hearing-impaired listeners, in E. F. Evans and J.…
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from article Masking of sound
Width of the critical band in hertz as a function of signal frequency.
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from article Masking of sound
Relative amount of masking obtained in forward, simultaneous, and backward masking. (After W. A. Yost, Fundamentals of Hearing: An Introduction, 4th ed., Academic Press, New York, 2000)
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from article Masking of sound
Masking of a 1000-Hz pure-tone signal in forward masking when the masker is a two-tone complex consisting of a 1000-Hz masker and a second tone. (a) Threshold of signal for the two-tone masker relative to that obtained when only the 1000-Hz tone…
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from article Polychaeta
Examples of polychaetes. (a) Platynereis dumerilii antipoda. (b) Branchiomma sp. (c) Arenicola bombayensi. (After P. L. Beesley et al., 2000)
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from article Polychaeta
Platynereis dumerilii antipoda, showing the antero-dorsal end with the pharynx everted. (After P. L. Beesley et al., 2000)
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from article Polychaeta
Hololepidella laingensis; scanning electron microscope view of the anterior end with the pharynx everted. An: antennae; Pa: palps; Prb: proboscis; Prs: prostomium; TeC: tentacular cirrus. Numbers refer to the segments of the trunk. Magnification,…
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from article Polychaeta
Gastrolepidia clavigera; scanning electron microscope view of the anterior end. Mo: mouth; Ja: jaw; Pa: palps; Prb: proboscis. Magnification, 30×.
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from article Polychaeta
Gastrolepidia clavigera, scanning electron microscope view of the two first parapodia (Pa1, Pa2). Ch: chaetae; Ci: cirrus; Nop: notopodium; Nep: neuropodium. Magnification, 40×.
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from article Polychaeta
Section through a polychaete. (After E. E. Ruppert and R. D. Barnes, Invertebrate Zoology, Saunders College Publishing, Orlando, 1994)
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from article Sound absorption
Absorption of sound in air at 20°C (68°F) and various values of relative humidity. (From L. E. Kinsler et al., Fundamentals of Acoustics, 3d ed., Wiley, 1982; used by permission of John Wiley & Sons, Inc.)
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from article Sound absorption
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from article Sound absorption
Depiction of direct and reflected sound in a room with varying wall properties.
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from article Sound absorption
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from article Chaetonotida
Marine gastrotrichs of the order Chaetonotida; dorsal views. (a) Xenotrichula (courtesy of W. D. Hummon). (b) Chaetonotus (after W. D. Hummon, Intertidal marine Gastrotricha from Colombia, Bull. Mar. Sci., 24:396–408, 1974).
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from article Radiation
Crepuscular rays, which are shafts of air illuminated by electromagnetic radiation (light) radiating from the Sun. [Credit: Danny Chapman / Flickr/ Attribution-ShareAlike 2.0 Generic ( CC BY-SA 2.0 )]
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from article Radiation
Illustration of gravitational radiation generated by the impending merger of two neutron stars. (Credit: R. Hurt/Caltech-JPL)
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from article Nitrogen oxides
Nitrogen-oxide structures. Blue = nitrogen. Red = oxygen.
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from article Centroids (mathematics)
Notation of integral equations for centroids. (a) Centroid of line. (b) Centroid of area.
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from article Centroids (mathematics)
Determination of centroids by summation. (a) Centroid of line. (b) Centroid of area.
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from article Centroids (mathematics)
Plane areas symmetric about a line.
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from article Centroids (mathematics)
Plane area symmetric about a point.
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from article Centroids (mathematics)
Use of the centroid of a line to find area of a face of revolution, according to Pappus' theorem.
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from article Doppler effect
The acoustical Doppler effect experienced by hearers of an ambulance siren. The sound waves emitted by the approaching ambulance compress into a higher frequency, resulting in a higher perceived pitch by the listener on the right. For the listener…
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from article Doppler effect
Motions of source, receiver, and propagating sound that produce the acoustical Doppler effect.
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from article Doppler effect
Motions of source and propagating light, in the system of the receiver, that produce the optical Doppler effect.
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from article Alpha particles
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from article Alpha particles
Locations of known alpha emitters on the chart of nuclides are shown in color. Boxes are included for all nuclides with proton number Z> 49 which have been observed. The fraction of the time that a particular nuclide decays by alpha-particle…
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from article Alpha particles
Range-energy relationship for alpha particles in silicon. 1 cm = 0.4 in.
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from article Alpha particles
Bragg curve for single alpha particle in air. The stopping power (specific ionization) in ion pairs per centimeter of air is plotted against residual range (distance from end of alpha particle's path) in centimeters. 1 cm = 0.4 in.
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from article Skink
Five-lined skink (Plestiodon fasciatus; formerly Eumeces fasciatus). (Credit: George W. Robinson; copyright © California Academy of Sciences)
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from article Vernier
Two types of vernier scales. (a) Direct (reading 3.6). (b) Retrograde (reading 12.7).
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from article Ephemeroptera
Ephemeroptera. (a) Mayfly, adult male, Hexagenia sp., in usual resting position (after A. H. Morgan, Field Book of Ponds and Streams, G. Putnam's Sons, 1930). (b) Mayfly, subadult male, Callibaetis sp., newly emerged from water, standing on surface…
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from article Lagrange's equations
The vector dr is decomposed into three orthogonal vectors of magnitudes r sin θ dϕ, rdθ, and dr, respectively, r, θ, and ϕ being spherical coordinates of the terminus of the vector r.
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from article Lagrange's equations
X, Y, and Z are Cartesian coordinates of the center of mass of dumbbell m1m2; θ and ϕ are the polar angles of the dumbbell axis in a set of axes parallel to fixed set of axes and with origin at center of mass.
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from article Prairie dog
Black-tailed prairie dogs (Cynomys ludovicianus). (Photo by Ron Singer, U.S. Fish and Wildlife Service)
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from article Percopsiformes
Trout-perch (Percopsis omiscomaycus). (Photo by Konrad P. Schmidt)
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from article Percopsiformes
Pirate perch (Aphredoderus sayanus). (Photo by Konrad P. Schmidt)
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from article Percopsiformes
Ozark cavefish (Amblyopsis rosae). (Photo courtesy of U.S. Fish and Wildlife Service)
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from article Prosobranchia
Common gastropods. (Top left) Murex troscheli. (Middle) Conus gloriamaris. (Top right) Lambis crocata. (Bottom) Angaria vicdani.
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from article Sauropterygia
Ceresiosaurus calcagnii, ventral view.
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from article Hyperbola
Hyperbola as a conic section.
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from article Hyperbola
Hyperbola as a locus of points.
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from article Alicyclic hydrocarbon
Internal bond angles (α) for (a–c) planar rings and (d) a tetrahedral carbon atom.
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from article Alicyclic hydrocarbon
Nonplanar (a) chair and (b) boat structures of cyclohexane.
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from article Alcohol
Ethanol production plant. (Credit: Julie Kendall/Getty Images)
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from article Alcohol
E85 is a gasoline-ethanol blend containing 51 to 83% ethanol. It is used in flexible-fuel vehicles, which can operate on gasoline or blends of gasoline and ethanol. About 20 million flexible-fuel vehicles are operating in the United States. (Credit:…
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from article Fluids
Probability of finding molecular centers at various separations in gases, liquids, and solids.
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from article Fluids
Conditions of pure-component phase behavior.
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from article Fluids
Behavior of pure-component pressures with density at various temperatures.
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from article Fluids
Behavior of pure-component compressibility factors with pressure at various temperatures.
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from article Giant nuclear resonances
Cross section of neutrons produced by gamma-ray bombardment as a function of the gamma-ray energy Eγ. The large peak is due to the giant electric dipole resonance. 1 barn = 10−28 m2. (After A. Veyssiere et al., Photoneutron cross sections of 208Pb…
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from article Giant nuclear resonances
Partial spectra of 120-MeV alpha particles scattered inelastically from lead-208 at angles of (a) 0° to 1.5° and (b) 1.5° to 3°. The broad peaks at excitation energies Ex near 11 and 14 MeV are the isoscalar giant quadrupole resonance and the…
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from article Giant nuclear resonances
Spectrum of neutrons emitted at 0° by bombarding zirconium-90 with 200-MeV protons. The broad peak at excitation energy Ex near 9 MeV is the giant Gamow-Teller resonance. (After T. N. Taddeucci, Polarization transfer in (p, n) reactions, Can. Phys.,…
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from article Zebu
Gray Brahman bull (Bos indicus). (Photo courtesy of Salinas Ranch, Carmine, Texas)
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from article Physical science
An astronaut conducts a physical science experiment aboard the International Space Station involving buoyancy-driven convection and sedimentation, which as force-dependent phenomena occur differently in a microgravity environment. (Credit: NASA)
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from article Photonic integrated circuits
Schematic cross section of the basic building blocks for InP-based PICs. SOA = semiconductor optical amplifier. (From M. Smit et al., 2014, published under a Creative Commons BY 3.0 license)
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from article Photonic integrated circuits
InP-based multiproject wafer (MPW) incorporating multiple PIC designs. (From M. Smit et al., 2014, published under a Creative Commons BY 3.0 license)
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from article Photonic integrated circuits
Cross-sectional view of a silicon-on-insulator (SOI) waveguide.
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from article Photonic integrated circuits
Building blocks of silicon photonics–based PICs. (Credit: Phil Saunders)
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from article Photonic integrated circuits
Silicon photonics–based PIC with heterogeneously integrated GaSb photodiodes for spectroscopic glucose sensing. (Credit: imec, Belgium)
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from article Tuning fork
Tuning fork vibrating at its fundamental frequency.
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from article Model theory
Conceptual model of a system.
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from article Model theory
Model of a regional population system.
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from article Biosynthesis
Biosynthetic relationships of some natural products. Specific examples which belong to the various classes are given in brackets.
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from article Thulium
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from article Diadematoida
Two ambulacral plates of Diadema. (After T. Mortensen, A Monograph of the Echinoidea, III, C. A. Reitzel, Copenhagen, 1943)
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from article Diadematoida
Diadema antillarum on coral reef. Spines are commonly black, but white spines, as shown here, are also frequently found. (Photo courtesy of J. E. Miller)
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from article Valvatida
Valvatid pedicellariae (valvate type) on marginal plates of Hippasteria trojana.
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from article Valvatida
Three-dimensional diagram showing the main ossicles of the valvatid arm.
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from article Electret
Schematic cross sections of electrets. (a) Solid electret disk metallized on one side with real charges (surface and space charges) and dipolar charges. (b) Cellular electret metallized on both sides with charges of opposite polarities on the upper…
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from article Turbulent flow
Two-dimensional image of an axisymmetric water jet, obtained by the laser-induced fluorescence technique. A neodymium:yttrium-aluminum-garnet laser beam, shaped into a sheet of 250-micrometer thickness by using suitable lenses, was directed into a…
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from article Turbulent flow
Typical signals of ε′, a component of the turbulent energy dissipation, normalized by its mean value 〈ε′〉. (a) Signal obtained in a laboratory turbulent boundary layer at a moderate Reynolds number (defined suitably). (b) Signal obtained in the…
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from article Remipedia
Representative Remipedia. (a) Speleonectes lucayensis (after F. R. Schram, Crustacea, Oxford University Press, New York, 1986). (b) Lasionectes entrichoma [after J. Yager and F. R. Schram, Lasionectes entrichoma, new genus, new species (Crustacea:…
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from article Chemistry
Periodic table. (Jaap Hart/Getty Images)
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from article Cumacea
A typical adult male cumacean.
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from article Mercury (element)
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from article Mercury (element)
Mercury droplets exhibiting non-wetting of the surface. (Credit: A. Cerar/Getty Images)
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from article Mercury (element)
Tooth with a silver-amalgam filling. (Credit: Szasz-Fabian Jozsef/Shutterstock.com)
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from article Magnon
Spin wave in a linear ferromagnetic array of precessing atomic spins of equal magnitude, represented as arrows (vectors) in perspective. The axis of precession is along the vertical direction of the total magnetization, M.
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from article Coronoidea
Stephanocrinus gemmiformis, Middle Silurian, Tennessee; side view of the theca.
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from article Supersymmetry
Dependence of the inverses of the three gauge coupling strengths, α1−1, α2−1, and α3−1, upon energy, μ, within the supersymmetric extension of the standard model. The difference in mass between the observed particles and their hypothesized…
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from article Supersymmetry
Dependence of the three inverse gauge coupling strengths upon energy, μ, within the unextended, nonsupersymmetric standard model.
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from article Organic conductor
Structures of organic conductors. (a) Electron donors. (b) Acceptor molecule (TCNQ) and two monovalent anions. Abbreviations are explained in the text.
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from article Organic conductor
Stacking of charge-transfer compounds. (a) Segregated stacking of TTF-TCNQ-like materials. (b) Typical zigzag stacking of the (TMTSF)2X series.
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from article Organic conductor
Comparison of the range of electrical conductivities of some AsF5-doped conducting polymers with some metals, semiconductors, and nonconducting polymers.
