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Project

Heart-Rate Monitor

This project uses a sensitive light-detecting resistor to detect small changes in the light beaming through your finger as your blood pumps through tiny arteries in the finger. This device is not the same as the heart-rate monitors typically used in…

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from article Perception

Perception encompasses recognition in response to sensory stimuli. Stimulation of the body's receptor organs is transformed into neural activity and is relayed to more central regions of the nervous system. Then, further neural processing occurs,…

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from article Perception

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from article Perception

Perceptual organization. (a) The figure of a four (4) is immediately and spontaneously perceived, despite the presence of other overlapping and adjacent lines. (b) The four, although physically present, is not spontaneously perceived and is even…

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from article Perception

Transposition of form; the two shapes look the same despite the difference in size.

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from article Perception

This figure is not recognizable. If, however, it is tilted 90° clockwise, it will be recognized as an outline map of Africa.

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from article Perception

Geometrical illusions. (a) The Ponzo illusion in which the two horizontal lines of equal length appear unequal. (b) The Poggendorff illusion in which the two oblique line segments are aligned with one another (that is, are collinear), but appear to…

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from article Derris

Derris elliptica. (Photo courtesy of Forest and Kim Starr)

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from article Optical coherence tomography

Typical optical coherence tomography system, based on a broadband source and fiber-optic Michelson interferometer.

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from article Optical coherence tomography

Optical coherence tomography images of healthy hamster skin in vivo. (a) Conventional magnitude image. Various layers of skin can be seen in cross section. (b) Result after Doppler processing of the same signal used to create the magnitude image.…

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from article Adenosine triphosphate (ATP)

Structure of adenosine triphosphate (ATP), which consists of ribose, adenine, and a triphosphate group (a chain of three phosphate groups, designated α, β, and γ). The structures of adenosine diphosphate (ADP), adenosine monophosphate (AMP), and…

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from article Adenosine triphosphate (ATP)

The ATP cycle, in which ATP is converted to ADP and phosphate (P), which is a process that creates energy for endergonic (energy-absorbing) reactions (for example, protein synthesis and muscle contraction); then, ADP is phosphorylated and converted…

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from article Poppy

Stems, fruits (capsules), and flower of the opium poppy (Papaver somniferum). By cutting into the fruits soon after the petals have fallen, the opium is obtained. (Photo courtesy of Milan Kořínek)

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from article Synthetic immunology

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from article Bioremediation

Contaminating oil spill on the surface of ocean water. (Credit: Steve Martarano/U.S. Fish and Wildlife Service)

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from article Bioremediation

Controlled oil burns were used to reduce the amount of surface oil following the Deepwater Horizon explosion in the Gulf of Mexico in 2010. (Credit: John Masson/U.S. Coast Guard)

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from article Bioremediation

Diagram of in situ bioremediation. Microorganisms and nutrients are introduced into the site, where they flow into the area containing pollutants. The bioremediation process is monitored, and water and by-products are extracted using wells. (Credit:…

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from article Cytoskeleton

Two interphase cells with immunofluorescence labeling of actin filaments (purple), microtubules (yellow), and nuclei (green). (Image by Torsten Wittmann, Scripps Research Institute, La Jolla, CA)

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from article Cytoskeleton

Endothelial cells from a cow lung showing two components of the cytoskeleton: actin filaments (red) and microtubules (green). (Image by Tina Carvalho)

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from article Cytomegalovirus infection

Photomicrograph of three enlarged cells with large intranuclear inclusions (each with a clear peripheral halo), which are characteristic of cytomegalovirus infection. In this particular case of an immunosuppressed patient, the cytomegalovirus…

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from article Cytomegalovirus infection

Cytomegalovirus virion inclusion. A transmission electron microscopic (TEM) image depicting cytomegalovirus virions (complete, mature virus particles) in an unknown tissue sample. (Credit: National Center for Immunization and Respiratory Diseases)

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from article Aortic body

Oval-shaped aortic bodies are found lying on the anterior and posterior surfaces of the aortic arch and pulmonary artery.

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from article Glyptodont

A glyptodont skeleton belonging to the type genus, Glyptodon. (Credit: Gyik Toma)

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from article Glyptodont

Reconstruction of Glyptotherium texanum from Arizona. (Credit: David D. Gillette; illustration by Bonnie Dalzell)

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from article Glyptodont

Hexagonal osteoderm (a protective bony plate) in (top) lateral view and (bottom) external view. (Credit: David D. Gillette)

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from article Glyptodont

Cutaway interpretation of the osteology (skeletal and bone structure) of Glyptotherium. (Credit: Larry Isham)

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from article Kenaf

Harvesting of kenaf (Hibiscus cannabinus) in Texas. (Photo by David Nance, Agricultural Research Service, U.S. Department of Agriculture)

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from article Electric organ (biology)

Representative electric fishes: (a) Electrophorus; (b) Torpedo; (c) Malapterurus; (d) Astroscopus; (e) Gnathonemus; (f) Gymnarchus; (g) Raja; (h) Gymnotus; (i) Sternarchus. Electric organs are shaded or solid and indicated by small arrows.…

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from article Electric organ (biology)

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from article Electric organ (biology)

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from article Electric organ (biology)

Current flow through a single electrocyte and fields around an electric fish. (a) Cross section of a flattened cell at rest. Each face is specifically permeable to K+ and the cell interior is at a negative potential. Because equal potentials are…

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from article Electric organ (biology)

Representative electrocytes. Body axes are indicated by the arrows except that the Torpedo electrocyte is shown ventral surface up. Innervation is indicated by branching, except for Malapterurus in which a single nerve fiber makes a single contact…

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from article Electric organ (biology)

Patterns of electric organ discharge. (A) An electric catfish; potentials recorded between head and tail in a small volume of water with head negativity upward. Pulses attain a maximum frequency of 190/s. (A′) Single pulse. (B–D) Weakly electric…

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from article Gene amplification

Gene amplification occurs when the number of copies of a specific gene sequence is disproportionately increased in the parent genome. In this case, the specific gene sequence is duplicated. (Credit: Mina Kang)

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from article Gene amplification

Amplification of DNA using the polymerase chain reaction (PCR) method. After 20 cycles, the selected sequence has been amplified about 106-fold. The colored region indicates the target DNA to be amplified. The shorter arrows represent the…

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from article Gene amplification

Three mechanisms of gene amplification; n, m, and o are genes or groups of genes in the process of amplification. (a) Rolling circle: genes are copied from a single-stranded circle; they become double-stranded subsequently. (b) Multiple initiation…

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from article Abaca

Abaca (Musa textilis) growing in the Philippines. (Photo courtesy of Afren de Guzman, Maitum Information Office, Sarangani, Philippines)

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from article Hardy-Weinberg formula

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from article Hardy-Weinberg formula

Application of the Hardy-Weinberg formula in the case of cystic fibrosis. There are about 100 times as many persons who are heterozygous carriers of the cystic fibrosis gene as there are persons who are homozygous for it. (Copyright © McGraw-Hill…

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from article Plant hormone receptors

Auxin signal transduction pathway. Aux/IAAs form dimers with ARFs bound to promoters of auxin-regulated genes, causing transcriptional repression. Repression is released when auxin binds to TIR1, promoting the interaction with Aux/IAAs, which are…

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from article Plant hormone receptors

Gibberellin signal transduction pathway. DELLA proteins repress gibberellin (GA) response in an as yet undefined mechanism. Gibberellin binding to GID1 promotes interaction of GID1 with DELLA proteins. The DELLA proteins are then ubiquitinated by…

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from article Respiratory system disorders

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from article Respiratory system disorders

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from article Osteoporosis

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from article Osteoporosis

Decrease in bone density with age in women. Before menopause, bone loss affects primarily the spine and hip (femur and pelvis); after menopause, bone loss is most pronounced in the radius bone of the forearm.

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from article Animal camouflage

A Vietnamese mossy frog (Theloderma corticale) uses camouflage to blend into its surroundings. (Credit: David M. Hunt/123RF)

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from article Animal camouflage

Three body pattern types—uniform, mottle, and disruptive—are universal for camouflage in the animal kingdom. These patterns have evolved in animals of every size and shape, including both invertebrates and vertebrates, and occur in aquatic and…

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from article Animal camouflage

Octopus vulgaris reacting to a diver (predator). The initial change from camouflaged to conspicuous takes only milliseconds (ms) as a result of direct neural control of the skin. Full expression of the threat display (right) is 2 s. Video frame…

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from article Animal camouflage

A visual sensorimotor assay for probing cuttlefish (Sepia officinalis) perception and subsequent dynamic camouflage. (Top) Visual backgrounds with different size, contrast, edge characteristics, and arrangement are perceived by the cuttlefish, which…

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from article Animal camouflage

Color matching of camouflaged cuttlefish when viewed by hypothetical dichromatic and trichromatic fish predators. (A) The pseudocolor image for simulating the human view of the cuttlefish at near-surface. This composite image was formed by using…

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from article Lyophilization

Apparatus for rapid high-vacuum desiccation of frozen suspensions of biologic materials. (After A. J. Salle, Fundamental Principles of Bacteriology, 4th ed., McGraw-Hill, New York, 1954)

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from article Hormone

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from article Hormone

Epinephrine (an adrenal hormone) binds to a hormone receptor in the plasma membrane of a cell, leading to a cascade of intracellular activations that regulate cell behavior. In this instance, the binding leads to activation of an enzyme that changes…

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from article Appendix (anatomy)

Junction of the human ileum and colon, showing the cecum and vermiform appendix. (From C. K. Weichert, Anatomy of the Chordates, 4th ed., McGraw-Hill, New York, 1970)

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from article Amino acid metabolism

The basic chemical structure of an amino acid, such as alanine, includes an amino group (—NH2) and an acidic carboxyl group (—COOH) attached to the same carbon atom, which also carries a hydrogen atom and a substituent group represented by the…

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from article Amino acid metabolism

Overview of amino acid metabolism. The major pathways and end products are shown in the illustration. Note that transamination involves the transfer of one or more amino groups from one compound to another, whereas deamination involves the removal…

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from article Personalized medicine

In the application of personalized medicine, physicians and other laboratory personnel utilize the latest genetic technologies in order to make a diagnosis or prescribe a treatment tailored to each individual patient. (Credit:…

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from article Personalized medicine

The ability to profile the structure, sequence, and expression levels of genes, proteins, and metabolites is redefining how diseases are classified and how treatments are selected, allowing physicians to go beyond the "one size fits all" model of…

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from article Personalized medicine

The success of personalized medicine will rise or fall on its ability to demonstrate its value to the health-care system, to the industries that develop its products, and to patients. (Credit: Tom Grill/JGI/Getty Images)

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from article Adipose tissue

Light micrograph of adipose (white fat) tissue. (Credit: Steve Gschmeissner/Science Photo Library/Alamy)

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from article Adipose tissue

White adipose cell with a large, single fat droplet. (Credit: T. L. Lentz)

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from article Adipose tissue

Brown adipose cell with many small lipid droplets. (Credit: T. L. Lentz)

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from article Protein kinase

Protein kinase cascades. (a) A general protein kinase cascade and (b) the Raf-MEK-ERK protein kinase cascade. Protein kinase cascades resulting in an inflammatory response and in apoptosis resemble the general protein kinase cascade. MAPKKK,…

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from article Avian influenza (bird flu)

After an influenza virus enters the human body, it attaches to cells within the nasal passages and throat (that is, the respiratory tract). The influenza virus's hemagglutinin (HA) surface proteins then specifically bind to the sialic acid receptors…

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from article Avian influenza (bird flu)

Genetic evolution of the H7N9 virus in China. The eight genes of the H7N9 virus are closely related to avian influenza viruses found in domestic ducks, wild birds, and domestic poultry in Asia. The virus probably emerged through reassortment, which…

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from article Robotic surgery

Sofie, a technology demonstrator for robotic minimally invasive surgery in the abdominal and thoracic cavity. (Credit: Bart van Overbeeke, Eindhoven, Netherlands)

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from article Robotic surgery

Pen-shaped handles of the controller interface.

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from article Robotic surgery

Table-mounted remote-manipulator system with one of three manipulator arms.

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from article Robotic surgery

Instrument with elbow-wrist configuration.

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from article Timothy

Common timothy (Phleum pratense). (Photo by J. Schmidt, Yellowstone National Park, U.S. National Park Service)

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from article Phosphorus cycle

Phosphorus cycle. ABC = Terrestrial and aquatic components. D = Human impact. Blue arrows = natural processes. Red arrows = human activities.

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from article Phosphorus cycle

Simplified geological phosphorus cycle.

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from article Phosphorus cycle

Phosphorus cycle in the soil-plant-animal system.

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from article Phosphorus cycle

Chemical structure of phytic acid (myo-inositol hexakisphosphate). P = PH2O3. (a) Hayworth projection. (b) Chair conformation.

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from article Phosphorus cycle

Human impact on the global phosphorus cycle.

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from article Phosphorus cycle

Impact of phytic acid in grain on phosphorus excretion in animal manures. The areas of the circles are in proportion to the amounts of phosphorus at each stage of the process.

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from article Intelligence

X-ray of a human brain. Intelligence involves the integrative and adaptive functions of the brain. (Credit: Getty Images)

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from article Intelligence

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from article Clostridium

Colored transmission electron micrograph of the Gram-positive anaerobic bacteria Clostridium botulinum. (Credit: Centers for Disease Control and Prevention)

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from article Clostridium

Photomicrograph of Clostridium perfringens using Gram's stain. Clostridium perfringens is a spore-forming, heat-resistant bacterium that can cause foodborne disease by contamination of raw food materials. (Credit: Don Stalons/Centers for Disease…

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from article Guayule

Flowering guayule (Parthenium argentatum). (Photo by Jack Dykinga, Agricultural Research Service, U.S. Department of Agriculture)

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from article Phase-contrast microscope

Effect of a partially absorbing object on a light wave. The diffracted wave is half a wavelength out of phase with the incident wave. A = incident wave; B = transmitted wave.

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from article Phase-contrast microscope

Effect of a transparent object on a light wave. (a) Incident wave A is unaltered in amplitude but delayed in phase and is transmitted as wave B. (b) B can again be represented as the sum of the incident wave A and a diffracted wave. The diffracted…

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from article Phase-contrast microscope

Diagram of a phase-contrast microscope. D = annular diaphragm; C = substage condenser; P = phase plate at rear focal plane of objective; S = specimen; E = eyepiece.

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from article Phase-contrast microscope

Phase-contrast photograph of living locust spermatocyte. (a) In a saline medium. The refractive index of the cell is so much higher than the index of the medium that all internal detail is obscured. (b) Similar cell immersed in 9% bovine plasma…

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from article Phase-contrast microscope

Phase-contrast microscope with vertical illumination for reflecting specimens.

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from article Opportunistic infections

Scanning electron micrograph of Mycobacterium tuberculosis bacteria, which cause tuberculosis. Mycobacterium tuberculosis bacteria can be both opportunistic and nonopportunistic. (Credit: National Institute of Allergy and Infectious Diseases)

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from article Opportunistic infections

Cryptococcosis of the lung in a patient with AIDS. Histopathology of the infected lung shows a widened alveolar septum containing a few inflammatory cells and numerous yeasts of Cryptococcus neoformans. The inner layer of the yeast capsule stains…

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from article Eucalyptus

Blue gum (Eucalyptus globulus) at Point Reyes National Seashore, California. (Credit: National Park Service)

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from article Eucalyptus

Flowers and leaves of blue gum (Eucalyptus globulus) at Haleakala Ranch, Maui, Hawaii. (Credit: Forest and Kim Starr)

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from article Hornbeam

Leaf of the American hornbeam (Carpinus caroliniana). (Photo courtesy of Robert H. Mohlenbrock, USDA–NRCS PLANTS Database)

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from article Cryobiology

Schematic representation of freezing system operation.

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from article Cryobiology

Liquid nitrogen container. 1 in. = 2.5 cm. 1 liter = 1.06 qt.

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from article Cryobiology

Liquid nitrogen container which is used for shipment of large samples. 1 in. = 2.5 cm. 1 ft = 0.3 m. 1 liter = 1.06 qt.

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from article Endocrine mechanisms

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from article Endocrine mechanisms

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from article Endocrine mechanisms

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from article Endocrine mechanisms

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from article Exon

Map of a eukaryotic gene, primary RNA transcript, and messenger RNA for a protein. Exons, the unmarked segments of the map, are separated by intron sequences, which are spliced out during synthesis of messenger RNA. The appearance of the 5′ cap, a…

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from article Alpaca

Alpacas (Vicugna pacos; formerly, Lama pacos) with different colored wool. (Credit: Brent Huffman/Ultimate Ungulate)

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