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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 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 Surveillance radar

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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 Island biogeography

Equilibrium number of species (Sequilibrium) is determined by the intersection of the immigration ( I ) and extinction ( E ) rate curves. P is the maximum number of species in the source pool.

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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 Biofilm

Biofilms are highly structured communities of microorganisms that are surface-associated or attached to one another, and are enclosed within a self-produced protective extracellular matrix. Biofilm formation and actions involve a number of stages:…

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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 Food science

Food scientist examining a tomato. (Credit: Adam Gault/Age Fotostock)

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from article Ecosystem

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from article Ecosystem

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from article Ecosystem

Food chains are limited by energy transfer. In this illustration, energy is transferred from the Sun to a plant (producer) to a primary consumer and to a secondary consumer. Energy is used by the producer and consumer organisms and is lost to the…

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from article Ecosystem

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from article Ecosystem

General model of the carbon cycle in ecosystems: (A) carbon dioxide (CO2) from the air; (B) carbon from decomposition; (C) carbon from fossil fuels; (D) natural events (for example, forest fires and volcanoes) release CO2 into the air. (Copyright ©…

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from article Biodiversity

Global biodiversity hotspots. There are more than 30 biodiversity hotspots located around the world. These areas have experienced severe habitat losses (at least 70%) as the result of human activities, hampering the work of conservationists in their…

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from article Biodiversity

A regional analysis of 25 oceanic regions shows that 92% of all known biodiversity falls into a dozen groups, of which crustaceans (for example, crabs, shrimps, and lobsters), mollusks (for example, snails, bivalves, squids, and octopus), and fish…

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from article Biodiversity

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from article Urodela

A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)

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from article Urodela

Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)

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from article Urodela

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from article Urodela

California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)

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from article Urodela

The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)

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from article Urodela

The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)

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from article Thirst and sodium appetite

Regulation of cellular water. ADH = antidiuretic hormone.

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from article Thirst and sodium appetite

Hypovolemic thirst and sodium appetite are caused by altered sensory information from an underfilled circulation, reinforced by increases in circulating angiotensin II and mineralocorticoids. Angiotensin peptides generated from components of a…

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from article Environmental management

Environmental management seeks to provide solutions to the practical problems that humans encounter or create, including the production of garbage and waste. (Credit: Walter Zerla/Getty Images)

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from article Environmental management

Without proper environmental management, economic and industrial development often lead to environmental pollution, especially in urban environments. (Credit: Simon Alvinge/123RF)

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from article Chicxulub impact crater

Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…

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from article Chicxulub impact crater

Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…

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from article Marine ecology

Marine ecology investigates the basic structural and functional relationships within and among living populations and their physical–chemical environments in marine ecosystems. In this photograph, a cold water reef in California is host to a…

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from article Marine ecology

The snaking waterways of a mangrove estuary in northwestern Madagascar. (Credit: Michael Fay/Getty Images/National Geographic RF)

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from article Marine ecology

Estuary salt marshes in the Grand Bay National Estuarine Research Reserve, Mississippi. (Credit: P. R. Hoar/National Oceanic and Atmospheric Administration)

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from article Marine ecology

Coral bleaching in the lagoon of Huahine Island, French Polynesia. Coral bleaching is the response of corals to environmental stress in which they eject the single-cell algae that live within the transparent coral tissue, making the white coral…

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from article Graptolithina

Sketches of portions of pterobranch and graptolite colonies showing the dwelling tubes and the constructional units of the graptolite skeleton. (a) Young Rhabdopleura compacta colony with founder zooid and first asexual bud (Recent). Benthic…

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from article Graptolithina

Scanning electron micrograph of a graptolite (Pseudoclimacograptus scharengergi) showing the fuselli (horizontal ridges) that compose graptolite thecae, and the cortical bandages (oblique strips) that were deposited on top of the fuselli (Middle…

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from article Graptolithina

Hypothetical form of zooids that inhabited colony tubes, based on a planktic graptolite. Large zooids are shown with possible oarlike swimming organs used to move the colony through the ocean water and tentacles for feeding. Also shown are two…

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from article Graptolithina

Examples of some planktic graptolites, reconstructed to show three-dimensional form.

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from article Swamp, marsh, and bog

Young cypress trees growing out of a swamp located in the Florida Everglades. (Credit: Getty Images)

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from article Plant vulnerability to climate change

Subarctic tundra and vegetation of the Denali National Park and Preserve in Alaska. As a result of climate change and the resultant poleward and upward shift of plant ranges, plants and their ecosystems may become particularly vulnerable. (Credit:…

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from article Plant vulnerability to climate change

Blue grama (Bouteloua gracilis) growing in Montana. As a result of warming temperatures, this type of grass could face decreased productivity, allowing forbs to increase and making the ecosystem less tolerant of drought and grazing. (Credit: Matt…

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from article Plant vulnerability to climate change

Modeled distribution of suitable climate space in Europe for stiff sedge (Carex bigelowii), which is an Arctic-Alpine plant: (a) during the period 1961–1990 (green color = suitable climate space during the 1961–1990 period); (b) climate model…

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from article Plant vulnerability to climate change

The endangered western prairie fringed orchid (Platanthera praeclara) is declining across much of its range in North America. (Credit: U.S. Fish and Wildlife Service)

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from article Palaeonisciformes

Mimia toombsi (Gardiner & Bartram, 1977), Late Devonian, Gogo, Australia. One of the earliest palaeonisciforms, reaching 15 cm (6 in.) long, and known by complete fossils. (Reprinted with permission from B. G. Gardiner, The relationships of the…

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from article Palaeonisciformes

Chirodus granulosus (Young, 1866) was a deep-bodied palaeonisciform that grew to 10 cm (4 in.) and lived in Carboniferous coal swamps of Britain. The teeth formed cutting blades that may have been used to crop vegetation. This reconstruction is…

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from article Ecological modeling

EverSnail ecological model (left) graphical interface and (right) snail kite holding an apple snail in its talons. The snail kite is an endangered species in the Florida Everglades, United States, and feeds on, almost exclusively, the apple snail.…

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from article Automatic landing system

Schematic of radar-beam system for aircraft-carrier and shore applications.

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from article Speech

Human head and thorax. (Courtesy of G. E. Peterson)

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from article Speech

Action of the glottis during speech. (a) Six successive positions of the vocal folds in one vibration cycle at 120 Hz. (b) Relation between pitch and vocal fold tension. (Courtesy of D. W. Farnsworth)

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from article Speech

Sound spectrograms of the utterance “speech production.” (a) Energy patterns: A, pulse; B, periodic; C, aperiodic; and D, silence. (b) The dotted lines represent the pitch pattern of the utterance.

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from article Speech

Computer-generated three-dimensional spectral display of the spoken syllable “yah.”

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from article Speech

Speech flakes of vowels in the words (a) “far,” (b) “food,” and (c) “fee.” (Courtesy of Charles Wooters)

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from article Speech

Regions of the brain involved in speech. (a) Left hemisphere, usually more involved in speech functions than the right hemisphere. (b) A model for the neural processes involved in speaking a heard word. Arrows indicate the path of the relayed signal…

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from article Wine

Stainless steel fermentation tanks (fermenters). (Credit: Granger Wootz/Blend Images LLC)

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from article Wine

Dark-skinned grapes ready for harvest in France. (Credit: Getty Images/RooM RF)

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from article Cashew

Cashew (Anacardium occidentale). The cashew nut is contained in a hard shell at the bottom of the fruit (cashew apple). (Credit: Laura Lartigue/U.S. Agency for International Development, Guinea)

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from article Biological insect control

The emerald ash borer (Agrilus planipennis) is an invasive pest insect that damages ash tree species in North America and Europe. Researchers are searching for natural enemies against the borer in its native range (Asia) to use as biological control…

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from article Altimeter

Schematic arrangement of sensitive pressure altimeter. 1 ft = 0.3 m.

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from article Altimeter

Radar altimeter principles. (a) Ideal return power distribution, which would be observed if the signal came only from the closest point to the radar. (b) Typical distribution of average returned power as a function of distance from the radar. (c)…

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from article Altimeter

Block diagrams of typical radar altimeters. (a) Automatic pulse altimeter. Control, tracking, and output circuits may all be digital. (b) Servo-adjusted-sweep FM altimeter.

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from article Cladoselache

Cladoselache fyleri, from the Upper Devonian of Cleveland. (After S. E. Bendix-Algreen, 1975)

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from article Salmon farming

Adult Atlantic salmon (Salmo salar). (Credit: William Hartley/U.S. Fish and Wildlife Service)

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from article Salmon farming

Atlantic salmon (Salmo salar) at a pre-smolt stage. (Credit: Edward Peter Steenstra/U.S. Fish and Wildlife Service)

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from article Salmon farming

A congregation of coho salmon (Oncorhynchus kisutch) released from a hatchery. Investigators continue to study the effects of farmed fish on neighboring populations of wild salmonids. (Credit: Salmon Ecology Team/Southwest Fisheries Science Center,…

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from article Jawless vertebrate

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from article Schuler pendulum

Basic principles illustrated by (a) simple pendulum; (b) Earth-radius pendulum; (c) solid pendulous rod.

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from article Schuler pendulum

Behavior of pendulous rod when accelerated about Earth. (a) Short-period pendulous rod. (b) Schuler-period pendulous rod. (c) Nonpendulous rod.

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from article Schuler pendulum

Gyropendulum; thrust bearing provides extra freedom, necessary for gyroscopic action.

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from article Schuler pendulum

Principle of Schuler-tuned stable platform.

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from article Psocoptera

Valenzuela flavidus, male (family Caeciliusidae): habitus (general appearance). Body length: 2.02 mm (0.08 in.).

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from article Psocoptera

Metylophorus novaescotiae, female (family Psocidae): habitus. Body length: 5.24 mm (0.2 in.).

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from article Psocoptera

(a–e) Mouthparts of a typical psocid, Echmepteryx hageni (family Lepidopsocidae): a = labrum, b = maxilla (l = lacinia), c = hypopharynx (li = lingual sclerite), d = mandible, e = labium. Scale: 0.1 mm (0.004 in.). (f) Wing venation of a typical…

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from article Psocoptera

Liposcelis brunnea, female (family Liposcelididae): habitus of a cleared specimen. Body length: 1.1 mm (0.043 in.).

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from article Stress (psychology)

Dimensions of stressful experiences. (Credit: National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health)

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from article Stress (psychology)

Diagram of the hypothalamic-pituitary-adrenal axis. The thicker arrow indicates that the feedback of glucocorticoids on ACTH is most potent. Abbreviations: ACTH, adrenocorticotropic hormone; CRH, corticotropin-releasing hormone. (Copyright ©…

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from article Devonian

Devonian, the fourth period of the Paleozoic Era.

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from article Devonian

Biostratigraphic zones based on conodonts (left) plotted to show approximate correspondence to the chronostratigraphic stages and series which compose the Devonian System (right) and relative sea-level changes (center) showing major fluctuations…

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from article Devonian

Reconstruction of Middle Devonian continental positions based on distribution of lithologic climatic indicators. Probable ocean currents derived from this paleogeography explain the biogeographic realms. Kolyma and Tarim are microcontinents of the…

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from article Obolellida

Obolella. (a) Shell exterior (after J. Hall and J. M. Clarke, An introduction to the study of the Brachiopoda intended as a handbook for the use of students, Report of the N.Y. State Geologist for 1891, 1894). (b) Dorsal valve interior, and (c)…

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from article Caraway