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Calcite concretion formed in Paleocene marine siltstone, Moeraki beach, New Zealand. Uncemented siltstone has been eroded away by wave action. Concretion is about 2 m (7 ft) in diameter, which is unusually large.

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from article Authigenic minerals

Scanning electron micrograph of authigenic kaolinite. The clay mineral formed from dissolution of calcic feldspar in a Miocene sandstone, San Joaquin basin, California.

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from article Authigenic minerals

Scanning electron micrograph of clinoptilolite zeolite (white crystals) on smectite-coated (dark background) sand grains. Sample is from Paleocene volcanic sandstone, Baja California, Mexico.

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from article Sonobuoy

Launch of a sonobuoy from an antisubmarine warfare (ASW) aircraft. (a) In flight. (b) Buoy strikes the water in a nearly vertical attitude. (c) Antenna and hydrophone are positioned automatically.

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from article Hematologic disorders

Myelophthisic anemia results from a space-occupying lesion in the bone marrow, which hinders hematopoiesis (the process by which the cellular elements of the blood are formed). In this photomicrograph, the bone marrow space is expanded, and the…

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from article Hematologic disorders

Scanning electron micrograph of (top) an elongated, flattened sickle cell and (bottom) a normal red blood cell. (Credit: Callista Images/Image Source/Getty Images)

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from article Hematologic disorders

Colored scanning electron micrograph of round leukocytes from a patient with leukemia. (Credit: Steve Gschmeissner/Science Photo Library)

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from article Engineering geology

Diagram of a typical landslide monitoring instrumentation. (Credit: USGS)

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from article Engineering geology

Rock-physics laboratory instrumentation for testing triaxial shear strength. Shearing stresses tend to separate portions of the rock (or soil) mass. Faults and folds are examples of shear failures in nature. In engineering structures, every…

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from article Engineering geology

Geologic map that can be used to identify geologic hazards and for land-use planning. (Credit: USGS)

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from article Sequence stratigraphy

Seismic reflection characterization. (a) Seismic transect across the western margin of Bimini Bank, Bahamas Platform, showing variations in seismic facies. Note the poorly reflective rocks at lower right, representing a sedimentary basement bounded…

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from article Sequence stratigraphy

Clastic-dominated sequence. (a) Model for clastic-dominated sequences on an extensional continental margin, showing the key stratigraphic surfaces and the four major systems tracts that develop within each sequence. Double-headed arrows show three…

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from article Cartography

Paper and smartphone maps for navigation. (Credit: Mmaxer/Shutterstock)

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from article Cartography

Distribution of chronic wasting disease of the deer family in North America, April 2018. (Credit: Bryan Richards, USGS National Wildlife Health Center)

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from article Cartography

Computer rendering of the topography of the 48 contiguous United States based on 12 million elevations. (USGS)

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from article Electric filter

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from article Electric filter

Passive, lumped-element filters. (a) RC low-pass filter. (b) LC band-pass filter.

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from article Electric filter

Ladder structure. (a) Overall structure with alternating series and shunt arms. (b) LC circuit whose impedance contains both a finite-frequency pole and a zero. Such circuits are used in the series and shunt arms of the ladder structure.

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from article Electric filter

Mechanical filter.

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from article Electric filter

Single-amplifier filters. (a) Low-pass Sallen-Key filter. (b) Low-pass, infinite-gain, single-amplifier filter. (c) Cascade of second-order filter realizations.

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from article Electric filter

Multiple-amplifier filters. (a) State-variable (KHN) filter. (b) Tow-Thomas filter.

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from article Electric filter

Simulated-inductor realization of fifth-order high-pass filter. (a) RLC prototype, normalized for cutoff frequency of 1 rad/s (0.159 Hz). (b) Direct active-RC realization.

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from article Satellite television broadcasting

Direct broadcasting television satellite system.

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from article Fungi

Porcini mushrooms (Boletus edulis) are members of the Basidiomycota division of Fungi. (Credit: Digoarpi/Shutterstock)

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from article Fungi

Spore types (upper illustrations) and structures of parent mycelia (lower illustrations) in fungi.

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from article Fungi

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from article Fungi

Sexual mechanisms in fungi: (a) gametic copulation; (b) gametangial copulation; (c) gamete-gametangial copulation; and (d) somatic copulation.

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from article Fungi

Colorized scanning electron micrograph of brewer's yeast cells (Saccharomyces cerevisiae). This fungus consists of single vegetative cells, and small daughter cells can be seen budding off from the larger cells. Brewer's yeast is used in the…

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from article Apple

Empire apple (Malus pumila). (Credit: Peggy Greb/Agricultural Research Service, United States Department of Agriculture)

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from article Apple

Apple trees in an orchard in late autumn. (Credit: Sandrine Bouvier/Alamy)

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from article Oolite

Plain light micrographs of thin sections of ooids and pisoids. (a) Oolite of Mississippian age, southwestern Indiana. (b) Pisoids from the hot springs of Karlovy Vary (Carlsbad), Czech Republic. The lower right pisoid shows a rock fragment nucleus…

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from article Pericycle

Pericycles. (a) Part of transection of root Actaea alba, including xylem and phloem. Pericycle thin-walled and one cell in radial dimension. (b) Part of transection of root of Smilax herbacea, including phloem. Pericycle thick-walled and four or…

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from article Pericycle

Transection of central part of sugarbeet. (After K. Esau, Hilgardia, 9(8), 1935)

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from article Medical bacteriology

Microscopic view of bacterial pneumonia, which is a type of pneumonia caused by bacterial infection. (Credit: Stocktrek Images/Corbis)

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from article Medical bacteriology

Bacteria culture growth on agar medium in a petri dish. (Credit: Sompraaong0042/Shutterstock)

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from article Genetically modified organism (GMO)

Transgenic zebrafish cells. Green fluorescent protein (GFP) is a fluorescent protein first discovered in the jellyfish Aequorea victoria. GFP is commonly used as a reporter of gene expression in other species. Here, GFP is expressed by zebrafish…

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from article Genetically modified organism (GMO)

Genome editing technologies. In particular, targeted nucleases are a powerful tool for precise genome editing in GMOs. Among these tools are (a) transcription activator-like effector nucleases (TALENs), (b) zinc-finger proteins (ZFPs), (c) homing…

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from article Wood anatomy

Annual tree rings are distinct features of wood anatomy. The combined concentric bands of light and dark areas can help investigators to determine the age of a tree. (Credit: DrimaFilm/Shutterstock)

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from article Wood anatomy

Light micrograph of a section through the stem of a lime tree (genus Tilia). The pith is at the center and is surrounded by a layer of wood (xylem). A thin cambium separates this from the phloem. An outer layer of collenchyma is enclosed by the…

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from article Wood anatomy

Structure of a typical hardwood. (Credit: U.S. Department of Agriculture)

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from article Wood anatomy

Structure of a typical softwood. (Credit: U.S. Department of Agriculture)

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from article Channelrhodopsin

Three-dimensional (3D) protein crystal structure of channelrhodopsin variant C1C2. (Image courtesy of Protein Data Bank 3UG9, Molecular Modeling Database 96737)

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from article Plague

Plague ecology in the United States. The left panel shows how plague occurs in nature among rodents. The right panel shows how plague is spread from rodents to humans and domestic animals. (Credit: Centers for Disease Control and Prevention)

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from article Atmospheric tides

Variation of tidal amplitudes with height. The shaded area shows the general range of solar diurnal and semidiurnal amplitudes (on a logarithmic scale) as a function of height. The line corresponds to amplitude varying inversely with the square root…

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from article Nursing

Nursing provides physical and emotional care to ailing individuals. (Credit: Fuse/Getty Images)

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from article Arales

Anthurium andraeanum (flamingo lily). (Photo courtesy of Forest and Kim Starr)

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from article Potato

Potato (Solanum tuberosum), also known as the Irish potato. (Credit: Peggy Greb/Agricultural Research Service, U.S. Department of Agriculture)

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from article Potato

Diagram of a potato plant. (Credit: Potato Association of America)

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from article Potato

Potato tubers infected by late blight (caused by Phytophthora infestans). (Credit: G. D. Franc)

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from article Persian melon

Persian melon (Cucumis melo). (Photo by Mehrdad Aref-Adib)

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from article Human ecology

Shacks and garbage along a dirty river in a slum in Manila, Philippines. Human ecology encompasses how individual people and their communities interact with their particular environment. In many cases, though, humans have created polluted…

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from article Human ecology

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from article Igneous rock

Some plutonic rock names and their volcanic equivalents.

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from article Igneous rock

IUGS classifications of gabbroic rocks (triangle AQP) and ultramafic rocks (triangle AFP). (From A. Streckeisen, To each plutonic rock its proper name, Earth Sci. Rev., 12:1–33, 1976)

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from article Igneous rock

Photomicrographs of common igneous rock textures. (a) Hypidiomorphic-granular texture. (b) Porphyritic texture. (c) Pyroclastic texture. Width of field of view is 3.2 mm (0.125 in.).

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from article Igneous rock

Photomicrographs of some mineral textures in igneous rocks. (a) Poikilitic texture in alkali feldspar. (b) Perthitic texture in alkali feldspar. (c) Zoned texture in plagioclase. Width of field of view is 3.2 mm (0.125 in.).

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from article Igneous rock

Some volcanic structures. (a) Lava plateau with flat-lying basalt lava flows, near Sprague, Washington. (b) Composite volcanoes, Atitlan (left) and Toliman in Guatemala. (c) Columnar jointing in andesite near Lost Creek Dam, Oregon. (d) Pillow…

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from article Igneous rock

Some plutonic structures.

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from article Type 1 diabetes

One characteristic feature of type 1 diabetes is glomerulosclerosis (Kimmelstiel-Wilson lesion), which involves the scarring or hardening of the glomeruli (blood vessels) in the kidneys. (Copyright © McGraw Hill)

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from article Type 1 diabetes

Stages in the development of type 1 diabetes. (Credit: Type 1 Diabetes TrialNet)

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from article Phyllite

Shiny folded phyllite with mica crystals too small to be seen with the naked eye. (Credit: Stephen Reynolds)

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from article Rock mechanics

Typical rock mass containing numerous discontinuities. The person in picture is conducting a scanline survey, where a tape is placed across the rock and detailed information is gathered on the fractures that intersect the scanline.

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from article Rock mechanics

(a) Uniaxial compression test, where an axial stress is applied to a core sample of rock and increased until failure. (b) Triaxial compression test, where a constant confining stress is first applied, then the axial stress is increased until failure.

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from article Rock mechanics

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from article Rock mechanics

(a) Example of the failure zone around an underground excavation (×, shear failure; o, tensile failure), calculated using the Rocscience Phase2 computer program. (b) Example of a shallow underground excavation where the failure mode is either…

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from article Rock mechanics

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from article Polypodiales

Licorice fern (Polypodium glycyrrhiza), a member of the order Polypodiales, in Olympic National Forest, Washington. (Photo courtesy of the U.S. Department of Agriculture, Forest Service)

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from article Polypodiales

Christmas fern (Polystichum acrostichoides). (Photo by James H. Miller, U.S. Department of Agriculture, Forest Service)

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from article Polypodiales

The sensitive fern (Onoclea sensibilis), a representative of the Polypodiales. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)

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from article Polypodiales

Types of steles in the Polypodiales: (a) Protostele. (b) Amphiphloic siphonostele. (c) Ectophloic siphonostele. (d) Dictyostele with central pith surrounded by xylem and phloem in the form of discrete vascular bundles; bands of parenchyma cells…

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from article Polypodiales

Life history of a fern: (1) the fern plant, or sporophyte, bearing sori, or clusters of sporangia, on its leaves; (2) a sporangium; (3) a tetrad of young spores; (4) the four mature spores that have come from the tetrad shown in part 3; (5) a spore…

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from article Polypodiales

Diagram of section through a fern leaf, showing details of a sorus. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)

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from article Polypodiales

Eastern marsh fern (Thelypteris palustris): sori on the pinnules of a fertile frond. (Photo by Rob Routledge, Sault College, Sault Ste. Marie, Ontario, Canada)

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from article Polypodiales

Diagram of a fern prothallium. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)

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from article Yeast

Colorized scanning electron micrograph (SEM) of Schizosaccharomyces pombe yeast. This single-celled fungus is studied widely as a model organism for eukaryotic cell division. It is a rod-shaped yeast that grows by elongation at its ends, and it…

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from article Yeast

Cell shapes of yeasts are extremely varied: (a) rectangular; (b) pear-shaped; (c) apiculate; (d) ogival; (e) spherical; (f) globose; (g) ellipsoidal (oval); (h) elongate; (i) tetrahedral. (Copyright © McGraw Hill)

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from article Yeast

Colorized scanning electron micrograph (SEM) of cells of brewer's yeast (Saccharomyces cerevisiae). This yeast consists of single vegetative cells. Small daughter cells can be seen budding off from the larger cells. Saccharomyces cerevisiae ferments…

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from article Yeast

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from article Yeast

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from article Yeast

A fluorescent antibody stain reveals the oval budding yeast cells of Candida albicans. This yeast is the most common human fungal pathogen. (Credit: Maxine Jalbert and Leo Kaufman/Centers for Disease Control and Prevention)

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from article Foodborne disease

Trichrome-stained photomicrograph of a Giardia lamblia trophozoite (a growing stage in the life cycle of certain protozoan parasites). This microorganism often causes giardiasis (a diarrheal foodborne illness). (Credit: Melanie Moser/Centers for…

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from article Foodborne disease

A cluster of norovirus particles. (Credit: Charles D. Humphrey/Centers for Disease Control and Prevention)

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from article Foodborne disease

Colored scanning electron micrograph showing Salmonella enterica bacteria (serotype Typhimurium; colorized red) invading an immune cell (colorized yellow). This bacterial species commonly causes food-associated gastroenteritis. (Credit: National…

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from article Foodborne disease

Close-up view of Campylobacter jejuni bacteria. This scanning electron microscope image shows the characteristic spiral (or corkscrew) shape of C. jejuni cells. (Credit: De Wood and Chris Pooley/Agricultural Research Service, U.S. Department of…

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from article Cabbage

Cabbage (Brassica oleracea var. capitata). (Joseph Harris Co., Inc., Rochester, New York)

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from article Chrysocolla

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from article Atmospheric acoustics

Frequency dependence of attenuation coefficient in units of decibels per 100 m (dB/328 ft), temperature of 20°C (68°F), and a relative humidity of 70%. Total attenuation from air absorption and contributions from classical absorption (that due to…

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from article Atmospheric acoustics

Diagram of reflection of sound from a flat ground surface with impedance Z, showing direct (R1) and reflected (R2) paths from source to receiver, source height hs, microphone height h, distance of propagation d, and angle of incidence or grazing…

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from article Atmospheric acoustics

Relative sound pressure levels (SPL) for propagation from a source over mown grass for source height of 1.8 m (6 ft), microphone height of 1.5 m (5 ft), and distances of propagation indicated.

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from article Atmospheric acoustics

Curved ray paths. (a) Refraction downward, during temperature inversion or downwind propagation. (b) Refraction upward, during temperature lapse or upwind propagation.

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from article Atmospheric acoustics

Representative long-range ray paths of sound radiating from a source in the atmosphere and traveling from west to east in Northern Hemisphere in winter. 1 km = 0.6 mi. (After T. F. Malone, ed., Compendium of Meteorology, American Meteorological…

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from article Atmospheric acoustics

Contour plot of sound levels in the presence of upward refraction in a turbulent atmosphere. The source is very close to the ground at zero range. The white areas are regions of higher sound levels.

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from article Atmospheric acoustics

Facsimile record of acoustic echo sounding of atmosphere at the South Pole, February 9, 1975. 300 m = 984 ft, 600 m = 1969 ft. Dark regions above 300 m altitude correspond to temperature inhomogeneities associated with the passage of convective…

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from article Surface waves

Definition sketch for an oscillatory wave.

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from article Surface waves

Fluid particle orbital motions in deep-and shallow-water oscillatory waves. SWL = still-water level.

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from article Surface waves

Definition sketch for a solitary wave. SWL = still-water level.

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from article Surface waves

Definition sketch for a surge wave.

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from article Layered intrusion

Sequence of crystallization from basaltic magma. (a) Hypothetical phase diagram showing the derivation of the sequence olivine cumulate, orthopyroxene-olivine cumulate, orthopyroxene cumulate, as observed in cyclic units near the base of many…

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from article Layered intrusion

A sequence of layers of near-constant thickness and aspect that show a rather abrupt transition from a base rich in pyroxene (pyroxene-plagioclase cumulate) to a top composed nearly entirely of plagioclase (plagioclase cumulate). Ice axe is…

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from article Layered intrusion

Photomicrograph of an olivine cumulate from the LaPerouse gabbro. Early-crystallized olivine grains (ol; now fractured and incipiently altered) are enclosed in interstitial plagioclase (pl) and orthopyroxene (px). Mineral proportions suggest that…

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