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from article Information processing (psychology)

The four major lobes of the cerebral cortex, that is, the frontal, parietal, temporal, and occipital lobes, are responsible for different aspects of information processing. (Copyright © McGraw-Hill Education)

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from article Information processing (psychology)

Horizontal associative memory with a serious associative interference problem (who plays tennis—John, Peter, or both?) and no encoding of where each proposition begins and ends. (Copyright © McGraw-Hill Education)

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from article Information processing (psychology)

Vertical associative memory where concepts are grouped into phrases and propositions by associating each concept to a higher-order node that represents the entire group. (Copyright © McGraw-Hill Education)

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from article Octopoda

An octopod swimming in the ocean. (Credit: Getty Images/iStockphoto)

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from article Octopoda

Hapalochlaena maculosa, the Southern or lesser blue-ringed octopus, has vivid, small blue rings on its body and arms, highlighted with black outlines. Location: Mrs. Watson's Bay, Lizard Island, Great Barrier Reef, Australia. (Credit: Clyde F. E.…

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from article Octopoda

Hapalochlaena fasciata, the blue-lined octopus, has vivid blue lines on its body and rings on its arms, highlighted with black outlines. Location: Long Reef, New South Wales, Australia. (Credit: Clyde F. E. Roper)

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from article Octopoda

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from article Polyplacophora

Chiton on a rock surface. (Photo courtesy of the NOAA Okeanos Explorer Program, National Oceanic and Atmospheric Administration)

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from article Polyplacophora

Polyplacophoran mollusk (chiton): (a) dorsal view; (b) ventral view.

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from article Clathrate compounds

Schematic drawing of the lattices of (a, c) urea and (b, d) thiourea; c and d show accommodation of unbranched and branched paraffin chains, respectively.

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from article Clathrate compounds

Molecular model of α-dextrin–iodine compound seen in the direction of the c axis, that is, in the direction of the iodine chains, which lie in channels.

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from article Trace fossils

Domichnial dwelling burrow with pelleted wall, probably created by a burrowing crustacean. Ophiomorpha, Cretaceous, North Dakota. (From W. Häntzschel, in C. Teichert, ed., Treatise on Invertebrate Paleontology, pt. W, revised, University of Kansas…

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from article Trace fossils

Highly branched, fodinichnial mining burrow, possibly produced by a deposit-feeding crustacean or worm. (a) Chondrites, Tertiary, Austria. (b) Chondrites, Tertiary, Spain. (From W. Häntzschel, in C. Teichert, ed., Treatise on Invertebrate…

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from article Trace fossils

Agrichnial farming trace of an unknown organism, composed of a hexagonal, meshlike network of tunnels. Paleodictyon, Tertiary, Poland. (Photograph by W. Häntzschel)

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from article Trace fossils

Agrichnial farming traces of unknown organisms, including a double-spiral tunnel (Spirorhaphe) and a meshlike network of tunnels (Paleodictyon). Tertiary, Austria. (Photograph by W. Häntzschel)

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from article Trace fossils

Loosely meandering, agrichnial farming trace of an unknown organism. Cosmorhaphe, Tertiary, Poland. (From W. Häntzschel, in C. Teichert, ed., Treatise on Invertebrate Paleontology, pt. W, revised, University of Kansas Press, 1975)

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from article Trace fossils

Praedichnial boring drilled in a bivalve shell by a carnivorous gastropod. Oichnus, Recent, Texas. (Photograph by A. A. Ekdale)

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from article Trace fossils

Tightly meandering, pascichnial grazing trail, created by an unknown worm. Helminthoida, Tertiary, Austria. (From W. Häntzschel, in C. Teichert, ed., Treatise on Invertebrate Paleontology, pt. W, revised, University of Kansas Press, 1975)

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from article Trace fossils

Repichnial trail of an arthropod, possibly a trilobite. Cruziana, Cambrian, Alberta. (Photograph by J. P. A. Magwood)

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from article Trace fossils

Unnamed escape structure (fugichnial trace) in sandstone. Cretaceous, Utah. (Photograph by A. A. Ekdale)

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from article Trace fossils

Cubichnial resting trace of an ophiuroid brittle star. Asteriacites, Jurassic, Germany. (Photograph by W. Häntzschel)

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from article Trace fossils

Complex, composite ichnofabric created by numerous successive phases of burrowing in a fine-grained pelagic carbonate deposit, which has been weakly cemented to become chalk. Upper Cretaceous, Denmark. (Photograph by A. A. Ekdale and R. G. Bromley)

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from article Guided missile

GBU-15 with data link system, mounted on F-4 Phantom II fighter. (Hughes Aircraft Co.)

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from article Guided missile

TOW (tube-launched, optically tracked, wire-guided) antitank missile and launch tube. Wings and tails fold to permit tube mounting. (Hughes Aircraft Co.)

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from article Guided missile

Launching of a field-mobile, short-range, all-weather surface-to-air Roland missile. The West German–French Roland has been licensed for production in the United States for use as a U.S. Army air defense weapon. (U.S. Army)

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from article Guided missile

F-15 Eagle fighter aircraft equipped with a mixture of short-range, infrared Sidewinder and medium-range, radar Sparrow air-to-air missiles. (McDonnell-Douglas)

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from article Guided missile

Phoenix long-range air-to-air supersonic missile. (a) Side view (Hughes Aircraft Co.). (b) Launch from F-14 fighter aircraft (U.S. Navy).

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from article Guided missile

Falcon air-to-air missile family, including missiles with infrared and radar guidance, and high-explosive and nuclear warheads. (Hughes Aircraft Co.)

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from article Guided missile

Tomahawk long-range, subsonic cruise missile. (a) Side view. (b) Submerged launch. Missile may also be launched from surface or air. (General Dynamics)

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from article Guided missile

Harpoon antiship cruise missile. (a) Ship-launched. (b) Air launch version on A-6 intruder attack aircraft. (McDonnell-Douglas)

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from article Guided missile

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from article Neandertals

Neandertal cranium excavated from Forbes' Quarry, Gibraltar. Note the pronounced brow ridges, large braincase, and receding forehead. (Credit: Clive Finlayson/Gibraltar Museum)

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from article Neandertals

Gorham's Cave, Gibraltar, is the last known site of Neandertal occupation, being dated possibly to 30,000 years ago. (Credit: Clive Finlayson/Gibraltar Museum)

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from article Neandertals

Reconstructed skull of a Neandertal from the cave at La Chapelle-aux-Saints, France. (Credit: Illustration adapted from an original drawing by M. F. Ashley Montagu)

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from article Root (botany)

Kinds of roots. (a) Adventitious, on a cutting or slip (geranium). (b) Prop and other adventitious (corn). (c) Fibrous adventitious (grass). (d) Primary, or taproot (dandelion). (e) Fleshy taproot (carrot). (f) Fleshy, fascicled adventitious…

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from article Root (botany)

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from article Root (botany)

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from article Root (botany)

Distribution of tissues in a typical root apex.

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from article Root (botany)

Transverse sections of roots, showing primary and secondary tissues. (a) Soybean. (b) Barley. (c) Soybean; enlarged part of a, showing early formation of cambium. (d) Soybean with abundant secondary tissue.

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from article Root (botany)

Diagrams of vascular transition in dicotyledonous seedling (beet, Beta vulgaris) from root tip upward to level of cotyledons. (a) Root is diarch; its vascular tissues are continuous with those of (e) the cotyledons through (b–d) the transition…

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from article Atomic bomb

The mushroom cloud over Nagasaki, Japan, after an atomic bomb was dropped by U.S. aircraft on August 9, 1945. (Credit: Everett Historical/Shutterstock)

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from article Atomic bomb

Conceptual diagrams illustrating the main features of (a) implosion type and (b) gun-barrel type of fission weapons. (Credit: A. DeVolpi)

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from article Hydroponics

Green- and red-leaf lettuce growing in a hydroponic vegetable garden on a bamboo fence. The pipes, which supply nutrients and water, are part of the hydroponic system. (Credit: Piyachok Thawornmat, Shutterstock)

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from article Hydroponics

Hydroponic techniques: (a) aerated standing culture; (b) flowing-solution culture with standing solution; (c) nutrient film technique; (d) aeroponics.

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from article Flower

Flower structure, median longitudinal section.

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from article Flower

Diagrammatic section of an orange blossom. (After J. B. Free, Insect Pollination of Crops, Academic Press, 1970)

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from article Flower

Flower of Penstemon, a member of the foxglove family, in section. (After C. E. Wood, Jr., A Student's Atlas of Flowering Plants: Some Dicotyledons of Eastern North America, Harper and Row, 1974)

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from article Flower

Longitudinal section of a flower bud and one carpel in section of blackberry (Rubus betulifolius). (After K. R. Robertson, The genera of Rosaceae in the southeastern United States, J. Arnold Arbor., 55:344–401, 1974)

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from article Flower

Placentation: (a) parietal, (b) axile, and (c) free central. (After P. H. Raven, R. F. Evert, and H. Curtis, Biology of Plants, Worth Publishers, 1976)

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from article Flower

Nectaries. (a) Cherry flower (after W. H. Brown, The bearing of nectaries on the phylogeny of flowering plants, Proc. Amer. Phil. Soc., 79:549–595, 1938). (b) Flower of nasturtium (after B. J. D. Meeuse, The Story of Pollination, Ronald Press,…

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from article Flower

Sunflower (Helianthus annuus) of the composite family. (a) Inflorescence in section. (b) Side view of ray floret. (c) Side view of tubular floret. (d) Section of tubular floret. (After J. B. Free, Insect Pollination of Crops, Academic Press, 1970)

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from article Flower

Successive stages of flower formation in a wood sorrel. (a) Sepals and petals already initiated; the androecium begins as five bumps on the floral apex; five more will be added. At maturity, five long stamens will alternate with five short ones. (b)…

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from article Flower

Lily anther. (a) Cross section of young anther showing four microsporangia with sporogenous tissue. (b) Cross section of mature anther with two pollen sacs containing pollen. (After A. W. Haupt, Plant Morphology, McGraw-Hill, 1953)

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from article Flower

Gametophyte: (a) embryo sac and (b) pollen tube. (After O. Tippo and W. L. Stern, Humanistic Botany, W. W. Norton, 1977)

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from article Tomato

Tomatoes (Solanum lycopersicum). (Credit: Peggy Greb, Agricultural Research Service, U.S. Department of Agriculture)

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from article Tomato

Tomato affected by anthracnose (caused by the fungus Colletotrichum phomoides). (Credit: U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)

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from article Tomato

Tomatoes showing blossom-end rot. (Credit: Mary Ann Hansen, Virginia Polytechnic Institute and State University)

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from article Electrolysis

Electrolysis cell in which the electrolyte is a solution of sodium chloride.

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from article Learning

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from article Learning

Brain activity can be recorded in various ways, from single-cell activity (top tracing) to the familiar electrical patterns ("brain waves") of an electroencephalogram (bottom tracing). (Credit: Based on an original drawing by C. Cotman and J.…

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from article Pine nut

Pine nuts in their hard shell (Mexican piñon pine, Pinus cembroides). (Photo by Steve Hurst, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)

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from article Pine nut

Cone containing pine nuts (stone pine, Pinus pinea). (Photo by Vito Buono, Bari, Italy)

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from article Ultracentrifuge

Diagram of an electrically driven analytical ultracentrifuge. (Beckman Instruments)

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from article Ultracentrifuge

Analytical rotor. (Beckman Instruments)

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from article Ultracentrifuge

Fixed-angle preparative rotor and tubes. (Beckman Instruments)

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from article Ctenothrissiformes

A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)

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from article Equisetales

Equisetum arvense. (a) Sterile shoot. (b) Fertile shoot growing from an underground rootstock. (c) Cone. (d) Two views of shield-shaped sporangiophores. (e) Spores, greatly enlarged. As spore dries, elaters expand. (After E. W. Sinnott and K. S.…

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from article Equisetales

Equisetum gametophyte. (a) Small gametophyte, showing antheridia only. (b) Male gametes. (c) Larger gametophyte; branching lobes have archegonia at bases. (After E. W. Sinnott and K. S. Wilson, Botany: Principles and Problems, 6th ed., McGraw-Hill,…

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from article Equisetales

Sporophytes. (a) Equisetum gametophyte with sporophytes. (b, c, d) The young sporophytes of Equisetum hiemale. (After G. M. Smith, Cryptogamic Botany, vol. 2, 2d ed., McGraw-Hill, 1955)

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from article Animal testing

Mice are the most commonly used vertebrate species in animal testing and research. (Credit: Dolores Bonaparte)

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from article Animal testing

The use of animals in biomedical research remains essential, but the handling of these sentient beings must be done humanely to minimize and prevent animal harm. (Credit: U.S. Department of Agriculture)

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from article Pathotoxin

Oat seedling resistant to Victoria blight obtained by screening a susceptible population with the pathotoxin victorin, a product of the pathogen Helminthosporium victoriae.

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from article Pathotoxin

Separation of corn seedlings resistant (N) and susceptible (T) to southern corn leaf blight by treatment with a pathotoxin produced by Helminthosporium maydis race T.

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from article Pathotoxin

Chemical structures of four pathotoxins. (a) Fusicoccin. (b) Tentoxin. (c) AM-toxin. (d) HMT-toxin.

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from article Tree ferns

Cyathea cooperi (Australian tree fern), a common member of the family Cyatheaceae. (Photo by Forest and Kim Starr)

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from article Tree ferns

Arrangement of leaves of Cyathea cooperi (Australian tree fern). (Photo by Bryan Harry, Haleakalā National Park, National Park Service, Maui, Hawaii)

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from article Circadian clock (plants)

Three-module circadian clock system.

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from article Circadian clock (plants)

Model of the Arabidopsis circadian clock, showing light input (bold arrow), the central oscillator (large box) and output/response (tinted arrows). Light signals synchronize the clock via the cryptochromes (cry) and phytochromes (phy). These are…

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from article Triple point

Phase diagram for water, showing gas, liquid, and several solid (ice) phases; triple points at A, B, and C. The pressure scale changes at 101 kilopascals from logarithmic scale at low pressure to linear at high pressure.

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from article Macrocyclic compound

Macrocyclic structures. (a) Two crown ethers. (b) A basic structure for three cryptands. (c) A lariat ether. (d) All-aliphatic spherand. (e) All-aromatic spherand.

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from article Macrocyclic compound

Macrocycles with various structural features. (a) Bicyclic cryptand (ditopic receptor). (b) Calix[6]arene; R represents a functional group. (c) Cavitand. (d) Carcerand. (e) Cyclophanes.

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from article Macrocyclic compound

Tetramers. (a) Resorcinarene having the rctt conformation. (b) Pyrogallolarene having the rccc conformation.

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from article Macrocyclic compound

The metal cation is the guest and the organic structure is the host in (a) 18-crown-6 complex of potassium cation (K+) and (b) sodium (Na+) complexed by a calix[4]arene.

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from article Macrocyclic compound

Complexing species. (a) Dibinaphtho-22-crown-6. (b) R,R-dibinaphtho-22-crown-6 complex of phenethylammonium chloride.

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from article Macrocyclic compound

Affinities for anions and cations shown for (a) pyrrole and (b) furan-derived cyclic tetramers.

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from article Macrocyclic compound

Amphiphiles. (a) Crown ether-steroid amphiphile. (b) Crown ether bolaamphiphile.

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from article Salicylate

Chemical structures of (a) salicylate, the conjugate base of (b) salicylic acid, and the nonsteroidal anti-inflammatory drug (NSAID) (c) acetylsalicylic acid (aspirin).

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from article Marcus equation

Free-energy plot for an electron-transfer reaction with zero standard free-energy change (an electron self-exchange reaction).

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from article Marcus equation

Free-energy plot for an electron-transfer reaction when the free-energy change (|Δ G °|) is less than the reorganization parameter (λ).

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from article Lead

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from article Lead

Galena (lead sulfide, PbS) is an ore mined for lead. (Credit: USGS)

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from article Oxygen toxicity

The dual effect of oxygen on biologic activity. Organisms that avail themselves of the enormous metabolic advantages provided by dioxygen (O2) must defend themselves against its toxicity. (Copyright © McGraw Hill)

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from article Hyperbolic geometry

Examples of simple hyperbolic knots and links. (a) Figure-8 knot. (b) Whitehead link.

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from article Transmission lines

Two common transmission lines for communication. (a) Coaxial cable. (b) Strip line.

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from article Transmission lines

Equivalent circuit that represents three sections of a lossless transmission line. Each section is of length Δz, and has an inductor (L) and capacitor (C). Voltages (V ) and currents (I ), and their differences (ΔV and ΔI ) between successive…

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from article Transmission lines

Signal detection on an oscilloscope. (a) Oscilloscope pictures of voltage pulses at three locations, z1, z2, and z3, on a transmission line, successively more distant from the signal generator. (b) Oscilloscope pictures of a periodic voltage sine…

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from article Transmission lines

Transmission line with characteristic impedance Zc, terminated in a load impedance ZL. A change of coordinate system (from z to ζ) is indicated.

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from article Transmission lines

Envelope of the voltage standing wave consisting of a wave propagating from z = −∞ and being reflected at z = 0. The wavelength, λ, and the maximum and minimum voltages, Vmax and Vmin , are indicated.

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from article Transmission lines

Two waveguides, with conventional coordinates. (a) Rectangular waveguide. (b) Cylindrical waveguide.

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from article Transmission lines

Dispersion curve for a rectangular waveguide of width a, showing relationship between the propagation constant, β, and the angular frequency, ω. Here, n specifies the mode of propagation, and c is the speed of light.

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