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from article Medical waste
The uniform international biohazard symbol.
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from article Convection in the Earth
Pattern of magnetic stripes over the Reykjanes Ridge southwest of Iceland. (After J. R. Heirtzler, X. LePichon, and J. G. Baron, Magnetic anomalies over the Reykjanes Ridge, Deep Sea Res., 13:427, 1966)
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from article Convection in the Earth
Geographic setting of the Kurile Trench off the Kamchatka Peninsula, showing the deep ocean trench and the characteristic line of volcanoes in the vicinity of the subduction zone. The sections A′ and B′ illustrate the bathymetry normal to the trench…
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from article Convection in the Earth
Characteristic variation of heat flow and bathymetry. (a) Variation of surface heat flow as a function of age of the ocean floor in millions of years before present for the Pacific, South Atlantic, and Indian oceans. (b) Variation of sea-floor…
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from article Convection in the Earth
Global seismicity showing surface projections of all earthquakes which occurred during 1965–1975 with magnitudes in the range 4.5–5.5. Plate boundaries are located along the seams marked by high frequency of earthquake occurrence.
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from article Convection in the Earth
Map of global tectonic and volcanic activity over the past million years. (After The Physical World, National Geographic Society, Van der Grinten projection, 1975)
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from article Seawater
Vertical distribution of phosphate (PO43−) at three stations to show a range of characteristics found in major oceanic regions. North Atlantic is from a region in the central North Atlantic northeast of Bermuda and North Pacific is from the central…
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from article Seawater
Vertical distribution of total carbon dioxide concentrations at locations in the North Atlantic and North Pacific. Below depths of a few hundred meters, the distributions are generally characteristic of fairly large regions in the two oceans.
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from article Seawater
Layers in seawater in a section through the Atlantic Ocean from the Greenland Sea (right) to the Weddell Sea (left). The thick line represents depth. (a) Potential temperature; contour values are in °C (°F). (b) Salinity; contours are in parts per…
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from article Seawater
Layers in seawater in a section through the western Indian Ocean from India (right) to Antarctica (left). The thick line represents depth. (a) Potential temperature; contour values are in °C (°F). (b) Salinity; contours are in parts per thousand.
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from article Seawater
Layers in seawater in a section through the Pacific Ocean from the Aleutian Islands (right) to the Ross Sea (left). The thick line represents depth. (a) Potential temperature; contour values are in °C (°F). (b) Salinity; contours are in parts per…
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from article Huntington's disease
Huntington's disease is a hereditary disorder that affects approximately five to ten of every 100,000 persons. The average age at onset is between 35 and 40 years. Invariably fatal, the disease progresses gradually over time. (Copyright ©…
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from article Cheese
Cheese being placed in brining tank (salt bath). (Credit: Westend61/Getty Images)
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from article Cheese
Cheese ripening. (Credit: Tom Paiva Photography/Blend Images)
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from article Cheese
Swiss cheese. (Credit: Tom Paiva Photography/Blend Images)
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from article Fruit, tree
Apple trees growing in an orchard. (Photo by Charles Rondeau)
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from article Fruit, tree
Apple scab on fruit. This disease, caused by the fungus Venturia inaequalis, leads to unsightly blemishes on ripe apples. (Photo courtesy of the University of Georgia Plant Pathology Archive)
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from article Fruit, tree
Brown rot, caused by the fungus Monilinia fructicola, on a peach. (Photo by Jonas Janner Hamann, Universidade Federal de Santa Maria, Brazil)
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from article Fruit, tree
Fire blight, caused by the bacterium Erwinia amylovora, on apple fruits and leaves. (Photo courtesy of the University of Georgia Plant Pathology Archive)
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from article Fruit, tree
Blue mold (Penicillium italicum) on a rotting orange. (Photo by G. L. Barron)
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from article Funariales
Funariales sporophytes. (a) Funaria hygrometrica, entire plant (after H. S. Conard, How To Know the Mosses, Jaques, 1944); (b) deoperculate capsule; (c) capsule tip enlarged. (d) Physcomitrium turbinatum (P. pyriform), entire plant; (e) capsule…
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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 Pharmacy
Pharmacy is the science dealing with the preparation and dispensing of medicinal or therapeutic drugs. (Credit: Sanchai Rat/Shutterstock)
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from article Ultrahigh-pressure metamorphism
Schematic cross-section contrasting the tectonic setting of generation and exhumation of (a) Alpine-type and (b) Pacific-type HP-UHP belts. (Modified after Maruyama et al., 1996)
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from article Ultrahigh-pressure metamorphism
P-T diagram showing (a) HP-UHP regimes and stability of coesite and diamond, (b) P-T-time paths for Dabie-Sulu eclogite and garnet peridotite, and (c) zoned zircon domains with sensitive high-resolution ion microprobe (SHRIMP) U/Pb ages for Sulu…
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from article Ultrahigh-pressure metamorphism
Photomicrographs of UHP index minerals. Inclusions of coesite in omphacite from (a) Dabie, and coesite pseudomorph in epidote from (b) Sulu, central-eastern China. Inclusions of (c) microdiamond in zircon, and (d) diamond + phengite in garnet, from…
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from article Barrier islands
Generalized profile across a barrier island complex showing various environments.
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from article Barrier islands
Sediment budget for barrier island complex. Solid lines are major interactions; broken lines are relatively minor intersections.
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from article Barrier islands
Maps showing major coastal environments and directions, and directions of coastal processes of (a) wave-dominated barrier islands and (b) mixed-energy barrier islands. Large arrows indicate wave direction, and small arrows indicate direction of…
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from article Hepatitis C virus
Chronic hepatitis C with portal inflammation and interface hepatitis (erosion of the limiting plate of periportal hepatocytes by infiltrating mononuclear cells). (Copyright © McGraw Hill)
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from article Hepatitis C virus
Natural history of chronic hepatitis C. It is presumed that liver fibrosis progresses in a linear course from the time of acquisition of the infection to the development of cirrhosis. Stages of fibrosis are from the METAVIR (meta-analysis of…
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from article Hepatitis C virus
The genomic structure of hepatitis C virus (HCV) and potential targets for therapy. Through analysis of the genomic structure of HCV, additional therapies (for example, serine protease inhibitors, helicase inhibitors, and RNA polymerase inhibitors)…
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from article Lignin-degrading fungi
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from article Lignin-degrading fungi
Close-up view of Pleurotus spp. fruiting bodies growing naturally on a dead tree log. The common name of oyster mushroom comes from the shell-like appearance of the fruiting body. Note the characteristic eccentric caps.
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from article Stishovite
Comparison of the mean index of refraction and specific gravity of stishovite and other polymorphic modifications of silica.
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from article Cryptochrome
Role of cryptochromes (CRY) in the sunlight-induced regulation of stem elongation and flowering time in plants. Via signal transduction through cryptochromes, sunlight directly stimulates both gene transcription in the nucleus and protein…
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from article Cryptochrome
Functions of cryptochromes in the mammalian circadian clock. Cryptochromes (CRY) and melanopsins (MOP) can mediate light signals for the photo-entrainment of the circadian clock. In addition, CRY acts as a component of the negative-feedback loop…
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from article Cryptochrome
Basic structure of cryptochromes, emphasizing the lack of a C-terminal extension in photolyase and the different sizes of C-terminal extensions in cryptochromes from various species. PHR indicates photolyase or photolyase-related regions. MTHF…
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from article Melanterite
Fibrous crust of melanterite (a common mineral) in a sample from Kremnitz, Hungary. (Specimen from Department of Geology, Bryn Mawr College)
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from article Tidal bore
Tidal curve of a river with a tidal bore.
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from article Tidal bore
Tidal bore of the Petitcodiac River, Bay of Fundy, New Brunswick, Canada. Rise of water is about 4 ft (1. 2 m). (New Brunswick Travel Bureau)
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from article Earth
The famous "Blue Marble" picture of Earth taken by astronauts during the Apollo 17 mission on December 7, 1972, while en route to the Moon. (Credit: NASA)
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from article Earth
Principal layers of Earth. (USGS)
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from article Earth
Global histogram (distribution of elevations) and hypsographic curve (cumulative elevations) of Earth's surface. (NOAA)
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from article Earth
Seafloor spreading. (USGS)
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from article Earth
Plate collisions: (a) continent-ocean plate collision; (b) continent-continent plate collision; (c) ocean-ocean plate collision. (USGS)
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from article Earth
Structure of the atmosphere. The log scale applies only to the ionization curve. 1 km = 0.6 mi; °F = (°C × 1.8) + 32.
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from article Sterilization
Diagrammatic sketch of an autoclave. (American Sterilizer Co.)
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from article Sterilization
Cobalt-60 furnace which is designed for experimental food sterilization.
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from article Sterilization
Van de Graaff generator principle; packaged products sterilized by means of a high-intensity electron beam which penetrates packages. (After W. M. Urbain, Food Eng., vol. 25, February 1953)
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from article Surgery
Medical personnel performing a surgical procedure in a modern operating room. (Credit: OJO Images Limited/Alamy Stock Photo)
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from article Surgery
Operative view illustrating the position of various surgical instruments, including a surgical telescope, used to make an incision in a patient. (Copyright © McGraw Hill)
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from article Surgery
Close-up view of a surgeon organizing the instruments required for an operation. (Credit: ER Productions Limited/Blend Images)
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from article Surgery
A medical operation involving a robot. Robotic surgery is being implemented to perform procedures that once required the presence of an expert surgeon. (Credit: Master Video/Shutterstock)
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from article Baltic Sea
Postglacial development of the Baltic: (a) Baltic Ice Sea, 12,000–8000 B.C.; (b) Yoldia Sea, 8000–7250 B.C.; (c) Ancylus Sea, 7250–2000 B.C.; (d) Littorina Sea, 2000–A.D. 500. (After K. Grasshoff, in S. P. Riley and G. Skirrow, eds., Chemical…
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from article Food allergy
Children (under the age of 18) who experience food allergies are more likely to experience other allergic conditions, including asthma (black), eczema/skin allergy (blue), and respiratory allergy (green). (Credit: National Center for Health…
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from article Food allergy
Allergic responses (immunological responses mediated by the IgE class of immunoglobulins) can be caused by certain foods. In a person with allergies, mast cells will be coated with IgE against one or a few antigens (allergens) that, upon entering…
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from article Food allergy
Peanuts are a common trigger of food allergies in both adults and children. (Credit: Christian Jung/Shutterstock)
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from article Grimmiales
Grimmia apocarpa; grows generally on rock. (a) Leaf. (b) Portion of base of leaf. (c) Apex of leaf. (d) Urn and peristome. (e) Capsule. (After W. H. Welch, Mosses of Indiana, Indiana Department of Conservation, 1957)
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from article Sport-related concussion
Sport-related concussion is among the most frequent injuries experienced by athletes participating in contact and collision sports, including football. (Credit: skynesher/Getty Images)
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from article Sport-related concussion
Medical imaging and scanning techniques can identify the brain areas affected by a sport-related concussion. (Credit: Puwadol Jaturawutthichai/Shutterstock)
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from article Sport-related concussion
A football helmet with anticoncussion padding. This type of helmet is recommended for youths who are active in contact and collision sports. (Copyright © McGraw-Hill Education)
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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 Ocean
Pacific Ocean, Santa Cruz, California, USA. (Credit: Shutterstock/Lerner Vadim)
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from article Ocean
Range of (a) salinity and (b) temperature in the world’s oceans.
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from article Ocean
Major currents of the world’s oceans.
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from article Ocean
Role of the winds in establishing major current gyres that span ocean basins. Gyres are closed circulatory systems that are larger than whirlpools or eddies.
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from article Amblygonite
Amblygonite. (Credit: RF Company/Alamy)
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from article Fingerprint identification
Typical inked fingerprint.
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from article Fingerprint identification
FBI fingerprint impressions from the investigation train bombing, March 22, 2004, Madrid Spain. (a) Charted fingerprint collected from Mayfield. (b) Charted latent finger print from the crime scene.
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from article Phlogopite
Polyhedral models showing the one-layer monoclinic phlogopite atomic structure illustrating (a) a projection down the b axis and (b) near a-axis projection. The structural unit consists of only one layer; note that both layers shown are identical.…
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from article Taxonomy
Taxonomies are hierarchical classifications of groups within groups. As an example, the common taxonomic ranks (domain, kingdom, phylum, subphylum, class, order, family, genus, and species) and their respective names for the eastern gray squirrel…
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from article Taxonomy
Taxonomies can be based on traditional phylogenies and cladistic classifications. (Copyright © McGraw-Hill Education)
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from article Desertification
Overgrazing on North American rangelands contributes to soil compaction and alters the composition of vegetation. (Credit: Thomas Wikle)
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from article Desertification
Desertification can be accelerated by cultivation in areas better suited for herding, such as this field in Ethiopia. (Credit: Thomas Wikle)
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from article Desertification
Grazing animals have contributed to desertification in Africa’s Sahel region. (Credit: Thomas Wikle)
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from article Rock
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from article Rock
Classification of psammitic and pelitic rocks based on proportions of the three most common clastic minerals: quartz, feldspars, and clays—excluding calcilutites and calcarenites. (After E. W. Heinrich, Microscopic Petrography, McGraw-Hill, 1956)
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from article Rock
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from article Rock
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from article Rock
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from article Binocular vision disorders
Exotropia (simulated photographically) is a misalignment of the eyes. In this type of manifest strabismus, one or both eyes turn outward. (Credit: Kerri McTigue)
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from article Binocular vision disorders
Esotropia (crossed eyes; simulated photographically) is a type of manifest strabismus in which one or both eyes turn inward. (Credit: Kerri McTigue)
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from article Varve
Varved sediment in two lake-bottom cores from modern glacier-fed lake (Hector lake, Alberta, Canada) Varves collected closer to the river inlet (left) are thicker and represent higher annual sedimentation rates. The length of each sequence shown is…
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from article Coronavirus
Highly magnified, digitally colorized electron micrograph of MERS-CoV virions (red color). (Credit: National Institute of Allergy and Infectious Diseases)
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from article Coronavirus
Illustration of SARS-CoV-2. Note the spike (S) proteins protruding from the surface of the coronavirus, which impart the look of the Sun's corona or crown. S proteins bind to host cell receptors for entry or infection of the cell. (Credit: Alissa…
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from article Coronavirus
Classification of coronaviruses. Human coronaviruses are shown in bold type. Highly pathogenic coronaviruses in humans are shown in red type. Human coronaviruses belong to two different genera: Betacoronavirus and Alphacoronavirus. (Credit: Teri…
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from article Coronavirus
Primary and intermediate hosts of human coronaviruses showing cross-species transmission. No concrete evidence exists about the intermediate host (or hosts) of HCoV NL63 and HCoV HKU1. The years of isolation or emergences of each viral strain are…
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from article Corallinales
Articulated coralline red algae (genus Calliarthron, order Corallinales) found off the California coast in the Pacific Ocean. (Photo by Steve Lonhart, Monterey Bay National Marine Sanctuary, National Oceanic and Atmospheric Administration)
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from article Synaptic transmission
Synaptic transmission enables a neuron to communicate with a target cell across a synapse. During synaptic transmission, a presynaptic neuron releases a neurotransmitter, which then binds to specific postsynaptic receptors. (Copyright © McGraw Hill)
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from article Synaptic transmission
Types of synapses: (a) an electrical synapse, showing the plasma membranes of the presynaptic and postsynaptic cells linked by gap junctions; (b) a chemical synapse, showing neurotransmitters released by the presynaptic cell diffusing across the…
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from article Synaptic transmission
Ultrastructure of exocytosis at the neuromuscular junction. (a) Thin-section electron micrograph of a neuromuscular junction from the sartorius muscle of a resting frog. Vesicles are clustered in the presynaptic terminal at one of many active zones;…
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from article Noradrenergic system
Chemical structure of norepinephrine (C8H11NO3).
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from article Noradrenergic system
The relationship between norepinephrine and G proteins. Binding of norepinephrine to a receptor leads to activation of G proteins, which in turn modulate the activity of other proteins (enzymes or ion channels) in the cell. Terms: ATP, adenosine…
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from article Laminariales
Laminaria: (a) sporophyte; (b) cross section of blade, showing a sorus of unilocular sporangia interspersed with sterile hairs (paraphyses); (c) zoospore; (d) male gametophyte with antheridia; (e) antherozoid (sperm); (f) female gametophyte with…
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from article Laminariales
Giant kelp (Macrocystis pyrifera) can grow up to 0.6 m (2 ft) per day. Note the series of frond blades, with each subtended by a bladder. (Photo courtesy of Charlotte Stevenson, University of Southern California Sea Grant, Los Angeles)
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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.
