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from article Stereophonic radio transmission
Baseband spectrum of an FM stereo signal. This audio and supersonic spectrum is frequency-modulated onto a radio-frequency carrier.
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from article Video disk
DVD operational principles.
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from article Heterodonta
Common heterodont bivalves. (Credit: Ronald V. Dimock, Jr.)
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from article Heterodonta
Common heterodont bivalves. (Credit: Ronald V. Dimock, Jr.)
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from article Airborne radar
Radar presentation showing a squall line extending from northwest to southeast. The range marks, indicating 5-mi (8-km) units, give estimation of extent of disturbance. (RCA Corp.)
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from article Airborne radar
High-resolution radar map of a golf course near Stockbridge, New York. (M.I.T.-Lincoln Laboratory)
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from article Mixer
Linear mixers. (a) Passive linear mixer based on a resistive summing network. (b) Active linear mixer with an operational amplifier.
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from article Mixer
Balanced modulator (nonlinear mixer). Only signal paths are shown. Biasing must be added.
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from article Restoration ecology
Restored sand dune habitat at Cape Canaveral, Florida. To help prevent erosion, 180,000 shrubs, including grasses, sunflowers, vines, sea grapes, and saw palmettos, were planted. (Credit: Dan Casper/National Aeronautics and Space Administration)
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from article Behavioral psychophysics
Diagram of the apparatus for measuring the pigeon's absolute visual threshold. (After D S. Blough, A method for obtaining psychophysical thresholds from the pigeon, J. Exp. Anal. Behav., 1:31–43, 1958)
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from article Systems integration
Systems integration activity, showing the architecture for the system.
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from article Systems integration
Tactical and strategic perspective of systems integration, showing essential elements.
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from article Biological productivity
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from article Regular polytopes
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from article Regular polytopes
Two regular polyhedrons. (a) Dodecahedron {5,3}. (b) Icosahedron {3,5}.
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from article Regular polytopes
Two of the six regular four-dimensional polytopes. (a) The 5-cell {3,3,3}. (b) The 8-cell {4,3,3}.
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from article Wi-Fi
802.11 WiFi wireless router (access point). (Credit: Copyright © Sheval/Alamy)
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from article Wi-Fi
Wireless LAN architectures. (a) Independent basic service set. (b) Infrastructure basic service set. (c) Extended service set.
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from article Wi-Fi
Sending a data frame using carrier-sense multiple access with collision avoidance (CSMA/CA).
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from article Wi-Fi
Hidden-node problem for a wireless network.
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from article Analytic hierarchy
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from article Analytic hierarchy
Analytic hierarchy used to assist a family in buying a new car.
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Analytic hierarchy
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from article Cicada
Brood IX periodical cicada in Athens, West Virginia. (Photo by Louie H. Yang)
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from article Cicada
Periodical cicada life cycle. Counterclockwise from lower left: Nymphal cicada feeding on plant roots belowground; ants and other detrivores feeding on dead cicada litterfall; teneral adult cicada recently emerged from the nymphal exuviae; bird…
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from article Cicada
Brood X periodical cicadas in Boyce, Virginia. (Photo by Louie H. Yang)
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from article Reproductive behavior
The mating of dragonflies encompasses a number of reproductive behaviors. Typically, the male is in front and the female is behind. If the female is willing to mate, she bends her abdomen forward to collect sperm from the male's accessory genitalia,…
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from article Reproductive behavior
Sage-grouse lek. Males stake out and defend territories on a traditional breeding ground. Females breed with males in selected territories. (Credit: U.S. Fish and Wildlife Service)
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from article Reproductive behavior
Two bull northern elephant seals fighting for dominance on the beach. (Credit: eoind/Getty Images)
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from article Reproductive behavior
Natterjack toad giving a mating call with its vocal sac expanded. (Credit: Bobby Bok)
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from article Reproductive behavior
Mating behavior of sticklebacks: (a) zigzag dance of a male, which leads a female to the nest; (b) the male stimulates the female in the nest to lay eggs; (c) schematic portrayal of the events in a courtship sequence. (Credit: Based on original…
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from article Reproductive behavior
Lordosis in a female rodent. When mounted, the females of many mammalian species adopt the lordotic posture, rendering copulation possible. Note the concave arching of the spine. (Credit: Based on an original drawing by L. C. Drickamer and S. H.…
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from article Reproductive behavior
A black-browed albatross feeding a chick. This is one example in which parental care may be extensive and prolonged. (Credit: Vetta/Getty Images)
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from article World Wide Web
Structure of the Universal Resource Locator (URL). Color is for example only.
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from article Slime molds
Close-up view of slime mold on the ground. (Credit: Melinda Fawver/iStock/Getty Images)
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from article Slime molds
Plasmodial slime mold (Physarum polycephalum). (Credit: Jonatha M. Gott/Case Western Reserve University)
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from article Distance-measuring equipment
Block diagram of distance-measuring equipment system
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from article Coral bleaching
Coral reef at Kahului Point, Maui, Hawaii. (Left) Healthy corals are mostly brown or green in color as a result of the partner algae that live in the coral tissue. (Right) Because of heat stress to the corals, the algae can release toxic chemicals…
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from article Coral bleaching
Increases in temperature (in °F) in the surface waters of the Great Barrier Reef in Australia during the month of March since 1960. Water temperatures of just a few degrees above normal conditions have resulted in massive bleaching of corals.…
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from article Coral bleaching
Coral at Lizard Island, Australia. (Left) Bleached coral. (Right) Two months later, the coral had died and been overgrown by fleshy algae. (Credit: Richard Vevers and Christophe Bailhache/The Ocean Agency/XL Catlin Seaview Survey)
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from article Piloting
A fix from two bearings.
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from article Piloting
A fix which is obtained from a bearing and the distance of a single object. 6.3 mi = 10 km.
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from article Piloting
A horizontal danger angle.
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from article Operating system
Almost all computers use an operating system, such as mobile devices (smartphones and tablets), desktop and laptop computers, supercomputers, and even video-game consoles. (Credit: Shutterstock/Nik Merkulov)
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from article Rate-of-climb indicator
Rate-of-climb indicator or vertical-speed indicator. (a) Components. (b) Face. (After Federal Aviation Administration, Airframe and Powerplant Mechanics Airframe Handbook, AC 65-15A, 1976)
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from article Altitudinal vegetation zones
Vegetation zones and gradients of mean annual soil temperature, annual precipitation, and community diversity on the south slopes of the Santa Catalina Mountains, Arizona, a temperate mountain range. (After R. H. Whittaker and W. A. Niering,…
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from article Linguistics
Cortical areas of the brain that are specialized for language. Broca's area and Wernicke's area are involved in language and speech. Arrows indicate the Wernicke-Geschwind model for speech production. Information about spoken or written words is…
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from article Pulse modulation
Signal sampling and quantization. (a) Analog signal. (b) Corresponding pulse sequence.
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from article Pulse modulation
Forms of pulse modulation for the case where the analog signal, s(t), is a sine wave. (a) Analog signal, s(t).(b) Pulse-amplitude modulation. (c) Pulse-width modulation. (c) Pulse-position modulation.
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from article Pulse modulation
Pulse-code modulation. (a) Three successive quantized samples of an analog signal. (b) With pulses of amplitude V or 0. (c) With pulses of amplitude V or −V.
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from article Pulse modulation
Frame format for a T1 carrier, showing the arrangement of the pulses for one frame, corresponding to one sampling interval.
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from article Telephone service
Elements of the local telephone network.
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from article Telephone service
National long-distance telephone network of the early 1980s, which introduced common-channel interoffice signaling (CCIS) to speed call completions, using 14 special packet switches called signal transfer points. Regional, sectional, primary, and…
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from article Telephone service
National long-distance telephone network of the early 1990s, which uses common-channel Signaling System 7 technology. Signal transfer points serve local switches as well as the long-distance network with out-of-band access to various data banks, and…
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from article Telephone service
Caller identification service in Signaling System 7, whereby call waiting identifies the caller's name and directory number for waiting calls. Broken lines indicate SS7 links. (AT&T)
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from article Telephone service
Virtual private network with international links that must involve service providers of both the United States and other countries. (AT&T)
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from article Migratory behavior
Northern pintail ducks (Anas acuta) in migratory flight. (Credit: Josh Kelly/U.S. Fish and Wildlife Service)
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from article Migratory behavior
Monarch butterflies (Danaus plexippus) migrate from Canada and the northern United States in early autumn on a 2500-km (1550-mi) flight to Mexican wintering sites that are used year after year by individuals that have never been there before and…
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from article Systems ecology
Decrease in system productivity with loss of species: (a) Under the assumption that most species are redundant. Initial losses do not matter because the remaining species are able to carry out the ecosystem function necessary for production. (b)…
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from article Biome
Terrestrial biomes of the world. (Copyright © McGraw-Hill Education)
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from article Behavior genetics
DNA analysis can be used to determine the positions (loci) of genes on chromosomes. Each gene may come in several variations, called alleles, that may produce somewhat different phenotypic outcomes, influencing behavior. Molecular weight markers are…
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from article Behavior genetics
Alcoholism, a very complex behavioral disorder, results from the interplay of genetics, environment, and physiology in the context of development. (Credit: National Institute of Alcohol Abuse and Alcoholism)
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from article Coordinate systems
Cartesian coordinate system.
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from article Coordinate systems
Polar coordinate system.
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from article Coordinate systems
Spherical coordinate system.
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from article Computer-based systems
Model of a distributed computer-based system.
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from article Dead reckoning
Marine magnetic compass.
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from article Dead reckoning
Typical aeronautical deviation card.
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from article Dead reckoning
A plotter in use among air navigators.
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from article Hypnosis
A hypnotized individual appears to be in a trancelike state. This altered state of consciousness allows the individual to be more susceptible to suggestion than in his or her normal state. (Credit: Paula Connelly/Getty Images)
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from article Rose curve
Diagram of rose curve.
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from article Radio receiver
Simple tuned-radio-frequency (TRF) receiver for amplitude-modulated (AM) signals.
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from article Radio receiver
Superheterodyne (superhet) receivers. (a) Basic architecture. (b) Double superheterodyne, used to combat image response problems.
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from article Radio receiver
Phase-sensitive detector (PSD). (a) Diagram. (b) Waveforms of inputs and multiplier output. (c) Output from low-pass filter versus phase angle from inputs A and B. (d) Frequency demodulator using a phase-locked loop (PLL) with a phase-sensitive…
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from article Radio receiver
Frequency spectrum of frequency demodulator output in a radio receiver that generates stereo audio signals, showing content of the multiplex signal.
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from article Radio receiver
Process to extract left and right audio signals from a multiplex signal.
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from article Radio receiver
Homodyne (zero-intermediate-frequency) receiver.
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from article Radio receiver
Superheterodyne receiver with digital signal processing.
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from article Radio receiver
Frequency synthesizer used to generate accurate local oscillator frequencies.
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from article Dementia
Positron emission tomography (PET) scans show differences in glucose metabolism in a brain of a normal older adult (left) and a brain of an older adult patient afflicted with dementia as the result of Alzheimer's disease (right). Red and yellow…
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from article Dementia
The prevalence and annual incidence of dementia according to age group in older men and women. The rate of dementia (per 100 persons) is plotted against age group (years). (Copyright © McGraw-Hill Education)
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from article Optical communications
Block diagram of a simplified optical communications link.
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from article Optical communications
Optical communications spectrum with respect to the overall electromagnetic spectrum. LW = long-wave, MW = medium-wave, SW = short-wave, VHF = very high frequency, UHF = ultrahigh frequency.
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from article Optical communications
Low-loss spectrum of silica fiber used in fiber-optic wavelength-division multiplexing communications. The C-band is at a frequency of about 1550 nm (1.55 μm), and the L-band is at about 1600 nm (1.6 μm).
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from article Optical communications
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from article Optical communications
Use of optical-electrical-optical (OEO) amplifiers in a WDM link. This method is complex and cost-inefficient.
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from article Optical communications
Fundamental components of an erbium-doped fiber amplifer (EDFA) in a WDM system.
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from article Optical communications
Typical Raman gain coefficient over the amplification spectrum. In silica fiber at a wavelength of 1550 nm, the coefficient is 6.6 × 10−14 m/W.
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from article Optical communications
Optical switch with 4 × 4 MEMS micromirror matrix.
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from article Optical communications
Large optical network with wavelength converters. Such a network is able to concatenate wavelengths to establish an efficient end-to-end path. NMS = network management system, EMS = element management system, NE = network element.
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from article Optical communications
Large optical four-fiber Metro ring, with protection, loopback, and path switching. (a) System operating with no faults. (b) System using path switching to operate in the presence of a single fault. (c) System using loopback to operate in the…
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from article Positive psychology
All disciplines of psychology are concerned with the intertwining of human behavior and the functions of the mind. In particular, positive psychology investigates human happiness and the psychological bases by which humans flourish as individuals…
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from article Positive psychology
Psychologists who specialize in positive psychology help individuals to (1) define and assess well-being, (2) classify and assess character strengths, (3) understand the nature of positive emotions, and (4) determine what makes a positive…
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from article Rainforest
Clouds overlying a rainforest in Costa Rica. (Credit: John J. Mosesso/U.S. Geological Survey)
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from article Rainforest
Tree ferns and profuse tropical vegetation framing a mountainside waterfall (visible in the background) in a rainforest located on the Caribbean island of Dominica. (Credit: Randolph Femmer/U.S. Geological Survey)
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from article Limnology
Diagrammatic model of the functional linkages between terrestrial and aquatic ecosystems. Vectors may be meteorologic, hydrogeologic, or biologic components moving nutrients or energy along the pathway shown.
