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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 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 Biological productivity
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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 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 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 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 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 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 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.
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from article Limnology
Diagram of food webs in a lake, showing the interdependence of organisms. Broken lines depict the energy pathways and solid lines the food source.
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from article Limnology
A proposed relationship between stream size and the progressive shift in structural and functional attributes of lotic communities. Coarse particulate organic material (CPOM) that enters a stream from the watershed is shredded by organisms to form…
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from article Automatic horizon
Automatic horizon indicator. (Kollsman Instrument Co.)
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from article Space navigation and guidance
Jupiter flyby of a space probe in (a) Jupiter's frame of reference and (b) the Sun's frame of reference.
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from article Maternal behavior
In this display of maternal behavior, a mother robin pauses while feeding her three chicks. (Credit: Paul Mozell/Alamy Images)
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from article Maternal behavior
The mother cow is responsible for providing milk for the young calf. (Credit: Anjo Kan/Shutterstock)
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from article Myrmecochory
A carpenter ant, Camponotus castaneus, carrying a wild ginger seed in the southeastern United States. (Photo by Katharine L. Stuble)
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from article Myrmecochory
Polygala grandiflora seed with elaiosome. This plant species is dispersed by ants in the southeastern United States. (Photo by Katharine L. Stuble)
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from article Hallucination
Brain regions that may be involved in hallucinations. The thalamus, another important brain structure, is not depicted here as it is buried deep inside the brain. (Copyright © American Psychological Association; reproduced with permission from A.…
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from article Alcoholism
Deaths as a result of alcohol poisoning: (left) alcohol poisoning deaths are most common among middle-aged adults; (right) men are approximately three times more likely to die from alcohol poisoning compared to women. (Credit: National Vital…
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from article Alcoholism
Punctate hemorrhages in the mammillary bodies of the brain displaying evidence of Wernicke encephalopathy. This complication is often seen in chronic alcohol abusers and affects thiamine uptake and utilization. (Copyright © McGraw-Hill Education)
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from article Alcoholism
Alcohol dependence or abuse among adults aged 21 years or older within a 12-month period as a function of the age of the individual at the first use of alcohol. (Credit: Substance Abuse and Mental Health Services Administration, U.S. Department of…
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from article Electroencephalography
Normal EEG waves. (a) The alpha rhythm in the waking record blocks at eye opening; eyes opened at A and closed at B. (b) A light-sleep EEG has theta waves and a sleep hump at C and spindles at D. (c) Deep sleep reveals constant, irregular slow delta…
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from article Electroencephalography
Two examples of display conventions for topographic mapping. (a) Gray-scale technique, depicting amplitude of electrical discharge at particular points in time across the cortex. The maps display comparison of an individual's electroencephalogram…
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from article Electroencephalography
Primary elements of equipment required for topographic mapping of brain electrical activity.
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from article Vaquita
A vaquita (Phocoena sinus) in the waters close to San Felipe, Baja California, Mexico. (Credit: Tom Jefferson)
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from article Vaquita
A vaquita (Phocoena sinus) recovered from a shrimp gillnet. It is easy to notice the most conspicuous features of its coloration—that is, the large black patches around the eyes and lips. [Credit: Comisión Nacional de Áreas Naturales Protegidas…
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from article Vaquita
Decline in the vaquita population from 1997 to 2019. The current vaquita population is no more than 19 individuals, and the species may be extinct in a few years if fishery bycatch is not eliminated immediately. (Credit: Statista)
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from article Vaquita
A permanent gillnet exclusion zone covering the full range of the vaquita in the upper Gulf of California has been established to save the species. (Credit: T. J. Moore/U.S. Geological Survey; National Aeronautics and Space Administration)
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from article Tacan
Tacan transponder with rotating directional antenna system.
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from article Tacan
Composite radiated signal of Tacan transponder. Spaces between reference burst are filled with 2700 random DME replies per second.
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from article Tacan
Vortac system.
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from article Addiction and addictive disorders
Specific illicit drug dependence or abuse in a typical 12-month period among persons aged 12 years or older. (Credit: Illustration and data derived from the Substance Abuse and Mental Health Services Administration, U.S. Department of Health and…
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from article Addiction and addictive disorders
First specific drug associated with initiation of illicit drug use. (Credit: Illustration and data derived from the National Institute on Drug Abuse, U.S. National Institutes of Health)
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from article Addiction and addictive disorders
Structure of heroin. (Copyright © McGraw Hill)
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from article Addiction and addictive disorders
Structure of methadone. (Copyright © McGraw Hill)
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from article Persuasive technology
Individuals can achieve healthier lifestyles through persuasive technologies. A tracking bracelet collects data from various fitness activities (running, walking, sleeping, and other fitness pursuits). The data are then sent to a mobile phone with…
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from article Persuasive technology
Persuasive systems are computerized software or information systems designed to reinforce, change, or shape attitudes or behaviors (or both) without using coercion or deception. (Credit: shapecharge/Getty Images)
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from article Salt marsh
Salt marsh in Louisiana. Green plants in brackish water are observed in the foreground, whereas the ocean is seen in the background. (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)
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from article Salt marsh
California cordgrass (Spartina foliosa), a dominant salt-marsh plant, growing in the Tijuana Slough National Wildlife Refuge (located in southern California). (Credit: Lisa Cox/U.S. Fish and Wildlife Service)
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from article Salt marsh
An intertidal salt-marsh habitat on the Tijuana Slough National Wildlife Refuge (located in southern California). This habitat is an extremely diverse and productive ecosystem, filled with unique organisms. (Credit: Lisa Cox/U.S. Fish and Wildlife…
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from article Soil degradation
Soil degradation as a result of erosion in New Brunswick, Canada. (Credit: canadabrian/Alamy)
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from article Soil degradation
A pseudo-colored scanning electron micrograph (SEM) of Rhodococcus rhodochrous fermentation cells. Rhodococcus rhodochrous can degrade a diverse array of aromatic pollutants, including quinoline, pyridine, catechol, benzoate, and protocatechuic…
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from article Soil degradation
Surface water runoff can erode soils. In this case, the runoff from a rainstorm is eroding the soil of a cornfield. In addition, farm fertilizers and other potential pollutants are included in the runoff, often creating an environmentally toxic…
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from article Lie detector
A lie detector test or polygraph measures and records several physiological indices (for example, blood pressure, pulse, respiration, and skin conductivity) while a person is asked and answers a series of questions. The belief underpinning the use…
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from article Anorexia nervosa
Anorexia nervosa is a serious disorder and can have severe health consequences that go far beyond simple weight loss. (Credit: Office on Women's Health, U.S. Department of Health and Human Services)
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from article Anorexia nervosa
Incidence (%) of eating disorders among teenagers (13 to 18 years old) in the United States. Three types of eating disorders are included in the data: anorexia nervosa, bulimia nervosa, and binge eating disorder. Note that female teens are much more…
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from article Tropical forest
Tropical rainforest on Brunei. (Credit: Rodney Keenan)
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from article Tropical forest
Monsoon tropical forest in Queensland, Australia. (Credit: Rodney Keenan)
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from article Tropical forest
Tropical savanna forest in Northern Territory, Australia. (Credit: Rodney Keenan)
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from article Tropical forest
Natural forest areas (in thousands of hectares; 1 hectare = 2.47 acres) in various climatic domains (boreal/polar, temperate, subtropical, and tropical) from 1990 to 2015. The data are derived from the Global Forest Resources Assessment 2015 by the…
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from article Tropical forest
Tropical forest climatic zones around the world. Tropical rainforests are indicated by dark blue; tropical monsoon forests are indicated by a medium shade of blue; tropical savanna forests are indicated by light blue. (Credit: Based on data compiled…
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from article Aircraft collision avoidance system
Surveillance with Mode A/C transponders. (Reprinted with permission of MIT Lincoln Laboratory, Lexington, MA)
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from article Aircraft collision avoidance system
TCAS pilot displays. (a) Traffic advisory (TA) display. (b) Vertical resolution advisory (RA) display. (Reprinted with permission of MIT Lincoln Laboratory)
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from article Biogeochemistry
Biogeochemistry is concerned with both the biological uptake and release of nutrients, as shown for nitrogen. (Credit: U.S. Geological Survey)
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from article Biogeochemistry
Carbon cycle. Photosynthetic fluxes between the atmosphere and oceans, and the atmosphere and land, represent net primary productivity. Reservoir units, gigatons (1015 g) C; flux units, gigatons C/yr.
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from article Biogeochemistry
Terrestrial nitrogen cycle; organic nitrogen includes both particulate and dissolved material. Flux units, teragrams (1012 g) N/yr.
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from article Biogeochemistry
Marine nitrogen cycle; organic nitrogen includes both particulate and dissolved material. Flux units, teragrams (1012 g) N/yr.
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from article Biogeochemistry
Phosphorus cycle. Reservoir units, teragrams (1012 g) P; flux units, teragrams P/yr.
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from article Biogeochemistry
Sulfur cycle. Reservoir units, teragrams (1012 g) S; flux units, teragrams S/yr.
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from article Camel
Bactrian camel (Camelus bactrianus). (Photo courtesy of Brent Huffman, Ultimate Ungulate Images)
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from article Plant communication
Hillsides in central California covered by hard chaparral composed almost entirely of chemise shrubs. Chemise (also spelled chamise) produces allelopathic chemicals that, through plant communication, inhibit the germination of seeds and the…
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from article Soil
Soil supports plant growth. A pumpkin seed in nutritious soil sprouts and comes to life. (Credit: Redmal/Getty Images)
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from article Soil
A soil profile showing horizons. This particular soil belongs to the Dothan series of soils, which are very deep, well drained soils that form in thick beds of unconsolidated, medium- to fine-textured marine sediments. (Credit: John A. Kelley,…
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from article Soil
Erosion is an important concern of soil management. The soil along the river bank has eroded significantly, causing riparian trees to fall. (Credit: Hans Engbers, Shutterstock)
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from article Sleep-dependent memory processing
The sleep cycle, memory systems, and memory stages. (a) The human sleep cycle. Across the night, rapid eye movement (REM) sleep and non-REM (NREM) sleep cycle every 90 minutes in an ultradian manner (that is, occurring in cycles that are repeated…
