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from article Vibrotaction
Block diagram of apparatus for determining vibrotactile perception thresholds at the fingertip.
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from article Vibrotaction
Tactogram showing the approximate maximum threshold recorded at the fingertips of healthy persons (horizontal line), and examples of two types of threshold elevation (reduction in acuity) at selected frequencies (circles and squares).
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from article Forest ecosystem
Forest in Moran State Park on Orcas Island, Washington. (Credit: Chris Willig)
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from article Forest ecosystem
Forest fire in No Name Creek area of Colorado. (Credit: Andrea Booher/FEMA)
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from article Forest ecosystem
Puma and cub in forest. (Credit: Grant Faint/Stockbyte/Getty Images)
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from article Forest ecosystem
Conceptual model of elemental cycling in a terrestial ecosystem, emphasizing the presence and activities of arthropod consumers. The indirect regulation of elemental movement by arthropods is indicated by the hourglass-shaped valves on these flows.…
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from article Forest ecosystem
The southern pine beetle (Dendroctonus frontalis) is a destructive insect pest of coniferous forests in the southern United States. (Credit: U.S. Forest Service)
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from article Forest ecosystem
Belowground food web. (Credit: Elaine Ingham)
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from article Tangent
Line L tangent to curve C at P.
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from article Patellogastropoda
Whitecap limpet (Acmaea mitra). (Photo by Douglas Eernisse)
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from article Patellogastropoda
Ribbed Mediterranean limpet (Patella ferruginea). (Photo by Georgina Rivera Ingraham)
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from article Patellogastropoda
Radula of the patellogastropod Notoacmea scapha.
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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 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 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 Star tracker
Strapdown satellite star tracker. (a) Mounting of system on the satellite. (b) Star tracker in housing. (Northrop Grumman Corp.)
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from article Star tracker
Silicon focal-plane arrays. (Northrop Grumman Corp.)
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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 Nerve agent
Chemical structure of the nerve agent tabun (GA), C5H11N2O2P.
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from article Nerve agent
An example of hazardous materials workers wearing personal protective equipment (PPE), as might be worn to protect against nerve agent exposure. (Credit: CDC Public Health Image Library)
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from article Nerve agent
A practice exercise at the Centers for Disease Control and Prevention showing responders using a decontamination station, as might be used after a nerve agent incident. (Credit: CDC Public Health Image Library/Kathy Nellis Chastney)
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from article Nerve agent
Example of auto-injector syringes for atropine and pralidoxime, two antidotes for nerve agent exposure, from a Mark 1 Nerve Agent Antidote Kit (NAAK). (Credit: ATSDR/CDC)
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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 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)
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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 Streptococcus pneumoniae (pneumococcus)
Photomicrograph of Streptococcus pneumoniae bacteria that have been grown from a blood culture. Streptococcus pneumoniae is the most common bacterial cause of pneumonia in adults, but various forms of the bacteria have acquired resistance to…
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from article Sauropterygia
Ceresiosaurus calcagnii, ventral view.
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from article Hyperbola
Hyperbola as a conic section.
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from article Hyperbola
Hyperbola as a locus of points.
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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 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 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 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.
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from article Epidermal ridges
Characteristics of individual ridges and their configurations, seen in a print. (After H. Cummins and C. Midlo, Fingerprints: Palms and Soles, McGraw-Hill, 1943)
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from article Obesity
Map of the United States showing the growing prevalence of obesity. In general, the South had the highest prevalence of obesity, followed by the Midwest, the Northeast, and the West. (Credit: U.S. Centers for Disease Control and Prevention)
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from article Obesity
Colored scanning electron micrograph (SEM) of fat (adipose) tissue. The round fat cells (adipocytes) are surrounded by collagen fibers. Lipid is colored purple. Empty cells are seen at top right. (Credit: Science Photo Library/Alamy Stock Photo)
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from article Obesity
Estimated percentage of obesity according to gender. Dark color indicates the percentage of obesity in females; light color indicates the percentage of obesity in males. (Credit: National Institute of Diabetes and Digestive and Kidney Diseases,…
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from article Aspidorhynchiformes
Aspidorhynchus acutirostris, Upper Jurassic, Bavaria; a typical fish of the order Aspidorhynchiformes.
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from article Paleobotany
Compression specimen of the Triassic leaf type Dicroidium.
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from article Paleobotany
Permian pollen grain macerated from Antarctic coal.
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from article Paleobotany
Cross section of a permineralized stem from a Carboniferous coal ball.
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from article Paleobotany
Thin section of a petrified Rhynie chert stem.
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from article Paleobotany
Several coprolites found within the tissues of a Carboniferous plant.
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from article Paleobotany
Cuticle of a fossil (Eocene) leaf showing the outline of the epidermal cells and fungus with specialized hyphae.
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from article Paleobotany
Several Glossopteris leaves from the Permian of Antarctica. Leaves of this type were some of the first evidence that at one time the southern continents were all physically linked into a major continental plate called Gondwana.
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from article Paleobotany
Section showing tree rings from a temperate plant, showing change in cell size and wall thickness.
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from article Paleobotany
Section showing rings from a tree with uniform cell size and wall thickness, but growing at approximately 82° South during the Triassic.
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from article Osteolepiformes
Schematic phylogeny (family tree) of the osteolepiforms, based on arguments presented by P. Ahlberg and Z. Johanson (1998). The fishes within the gray zone are conventionally designated as Osteolepiformes (the formal group name), but they actually…
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from article Osteolepiformes
The tristichopterid Eusthenopteron foordi. (a) A close-up of its pectoral fin skeleton. (b) An illustration of the full specimen. Eusthenopteron reached approximately 50–70 cm in length. Its pectoral fin skeleton contains structures equivalent to…
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from article Parasympathetic nervous system
Overview of parasympathetic pathways of the human autonomic nervous system. Preganglionic axons from the brain and spinal cord innervate the viscera in the head, neck, and trunk. (Copyright © McGraw Hill)
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from article Fertilization (animal)
Photomicrograph (tinted green) of mouse sperm bound to the zona pellucida of an unfertilized egg under laboratory conditions (in vitro). (Credit: K. O. Kalthoff)
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from article Fertilization (animal)
Mammalian sperm (a) adhering to the zona pellucida, (b, c) undergoing the acrosome reaction, and (c, d) penetrating the zona pellucida on its way to the egg cell proper. (Copyright © McGraw Hill)
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from article Chemical senses
The sense of smell (olfaction) is a key chemical sense in vertebrates. (Left) Taste buds of the oral cavity, especially the tongue, are composed of modified epithelial cells responsive to chemicals in solution. (Right) Bitter, sour, salty, and sweet…
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from article Pigmentation
Colorful flower of Mirabilis jalapa. The colors of the flowers of this plant can vary as a result of different plant pigments. (Credit: F. D. Richards)
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from article Pigmentation
Zebrafish are often studied as model organisms for research dealing with skin pigmentation. (Credit: Lynn Ketchum/Oregon State University)
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from article Coronoidea
Stephanocrinus gemmiformis, Middle Silurian, Tennessee; side view of the theca.
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from article Neurohypophysis hormone
Structure of neurohypophysial hormones. Each neurohypophysial hormone is made up of nine amino acid residues with two half cysteines joined by a disulfide bridge to form a ring structure. Vasotocin is found in fishes and fetal pituitaries, while…
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from article Peroxisome
Electron micrograph of a cell of Yarrowia lipolytica (a type of yeast) grown in fatty acid–containing medium. (Copyright © McGraw Hill)
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from article Bipolar disorder
Prevalence of bipolar disorder in adults. The bar graph shows the percent of the U.S. adult population affected by bipolar disorder as it relates to age. (Credit: National Institute of Mental Health)
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from article Enzyme inhibition
Enzyme inhibition often works by preventing a substrate from attaching to an active enzyme. In this example, E1 is one of three sequential enzymes that will convert a substrate (S) into a product (P). However, the product that is created can then…
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from article Enzyme inhibition
Two types of reversible enzyme inhibition. (Left) In competitive inhibition, the inhibitor interferes with the active site of the enzyme, so the substrate is unable to bind to it. (Right) In noncompetitive inhibition, the inhibitor changes the…
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from article Docodonta
Restoration of the skull of the Late Jurassic docodont Haldanodon in lateral view. Arrow points to dentary-squamosal articulation; the articular-quadrate articulation lies directly behind it (toward the midline of the skull). (Illustration by…
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from article Docodonta
Upper and lower molars of Docodon, a Late Jurassic docodont. (a) Occlusal view of an upper molar. (b) Internal and (c) occlusal views of a lower molar.
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from article Geometrization theorem
Making a 2-D torus.
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from article Geometrization theorem
Life in Seifert-Weber dodecahedral space. (Courtesy of Geometry Center, University of Minnesota)
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from article Geometrization theorem
Hyperbolic dodecahedron of infinite diameter. The infinite spikes are rounded off “chimneys,” which are here triangular rather than rectangular. (Courtesy of Paul Nylander from http://bugman123.com/)
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from article Geometrization theorem
Neck pinching, resulting in infinite curvature.
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from article Geometrization theorem
Ricci flow with surgery.
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from article Neuroeconomics
Neuroeconomics applies neuroscientific tools and methodologies to investigate the decision making that occurs inside the brain. (Credit: James Steidl/SuperStock)
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from article Alpine vegetation
A windswept and stunted whitebark pine (Pinus albicaulis) growing among the alpine vegetation on Mount Washburn in Yellowstone National Park, Wyoming, United States. (Credit: R. G. Johnsson)
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from article Alpine vegetation
Alpine vegetation and flowers blooming in Mount Rainier National Park in Washington, United States. (Credit: National Park Service)
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from article Doppler VOR
Collocation of Doppler VOR and TACAN beacons installed on 100-foot high (30-m) tower with a counterpoise of 119-ft (36-m) diameter in forest near Frankfurt, Germany. Circular array consists of 39 loop antennas fed by solid-state commutator. Center…
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from article Doppler VOR
Principle of Doppler VOR beacon. Reference signal R and bearing signal V which is generated by dipole d are shown as they would be measured in aircraft to the north, east, south, and west of the beacon. (a) Dipole d at 180°. (b) Dipole d at 270°.…
