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from article Irrigation (agriculture)
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from article Irrigation (agriculture)
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from article Irrigation (agriculture)
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from article Irrigation (agriculture)
Furrow method of irrigation. Water is supplied by pipes with individual outlets, or by ditches and siphon tubes.
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from article Irrigation (agriculture)
A side-roll sprinkler system which uses the main supply line (often more than 1000 ft or 300 m long) to carry the sprinkler heads and as the axle for wheels.
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from article Irrigation (agriculture)
Center-pivot systems are very popular in new irrigation developments.
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from article Irrigation (agriculture)
Center-pivot irrigation system irrigating corn. A single unit can water as much as 500 acres (200 hectares) or more. (Eastern Iowa Light and Power Cooperative)
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from article Fire and disturbance ecology
Image taken in July 2012 showing the effects of a low-severity ground fire in a ponderosa pine (Pinus ponderosa)-dominated forest in the Sinlahekin Wildlife Area, Okanogan County, Washington. This was a prescribed fire and was applied to the…
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from article Fire and disturbance ecology
Image taken in October 2010 showing multiple fire scars in the tree rings of a cross section of a +400-year-old ponderosa pine (Pinus ponderosa) tree. The fire scars are the black curved lines near the bottom of the image. Each has been dated to the…
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from article Fire and disturbance ecology
Image showing a lake sediment core recovered from Sunrise Lake, Mount Rainier National Park, Washington, in August 2012. (Credit: Megan Walsh)
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from article Fire and disturbance ecology
Image showing a view of macroscopic charcoal under a stereomicroscope (approximately 40× magnification). Charcoal, which is created from the incomplete combustion of biomass, accumulates in lakes and wetlands following fire events and is preserved…
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from article Fire and disturbance ecology
Image showing the slow regrowth of a subalpine fir (Abies lasiocarpa)-dominated forest nearly 10 years after a high-severity, stand-replacing fire burned near Fish Lake in the Wallowa-Whitman National Forest, Oregon. (Credit: Megan Walsh)
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from article Fire and disturbance ecology
Image showing the cone of a lodgepole pine (Pinus contorta) that was heated, but not burned, during the September 2012 Table Mountain Fire near Ellensburg, Washington. Lodgepole pine cones are serotinous, meaning they are sealed with a waxy coating,…
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from article Fire and disturbance ecology
Image showing Oregon white oak (Quercus garryana) resprouting from the base of a tree burned in the August 2012 Taylor Bridge Fire near Ellensburg, Washington. This photo was taken in November 2012, only 2 months after the fire occurred, at which…
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from article Fire and disturbance ecology
Image showing the thickness of the bark on an old-growth Douglas-fir tree found in the Willamette National Forest, near Lowell, Oregon. Look near the middle of the trunk and you can see that the bark on this tree is almost 10 cm thick. (Credit:…
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from article Fire and disturbance ecology
Image showing the aftermath of the Taylor Bridge Fire, a stand-replacing fire that burned near Ellensburg, Washington, in August 2012. This forest, which is dominated by ponderosa pine (Pinus ponderosa), historically experienced frequent,…
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from article Genetically engineered plants
Stalks of genetically engineered barley. This particular genetically engineered plant carries a gene that helps it to resist attack by barley yellow dwarf virus. (Credit: Jack Dykinga/Agricultural Research Service, U.S. Department of Agriculture)
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from article Genetically engineered plants
Plasmid vector schematic illustrating the common elements of a plasmid vector that is used to deliver the gene (or genes) of interest to plant cells that have been prepped for transformation. Depending on the transformation technique, the components…
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from article Genetically engineered plants
A simplified schematic showing the elements of a gene gun as used in biolistic transformation of plant cells. Plasmid vectors that contain the gene of interest and other vector components are purified and coated onto microscopic particles of gold or…
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from article Genetically engineered plants
The basic steps in transforming plants using Agrobacterium-mediated transformation. Tumor-inducing (Ti) plasmid vectors are manipulated to remove the opine production genes, which the bacterium transfers to the plant in nature. In their place,…
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from article Genetically engineered plants
The binary vector system allows scientists to manipulate only a small vector (plasmid B) that contains the T-DNA region (the DNA to be transferred to the plant), whereas other trans-acting components of the Ti plasmid that are needed for DNA…
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from article Supernova
Telescopic imagery of one of the closest supernovae in a generation, SN 2011fe, captured in January 2011. It exploded in the Pinwheel Galaxy, located about 21 million light-years away. The supernova, a Type Ia, shines brighter than its entire host…
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from article Supernova
Optical spectra of four supernovae, all about 1 week old, are shown, with types indicated in parentheses. The Si II line is used to identify Type Ia spectra. (Credit: Alex Filippenko)
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from article Supernova
Schematic light curves for supernovae of four types and for SN 1987A. The absolute values of magnitude are quite approximate as each curve depends upon uncertain distances and there can be considerable variation within each subclass (less in Type Ia…
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from article Supernova
Region of the Tarantula Nebula in the Large Magellanic Cloud (a) before Supernova 1987A (the star that exploded to create the supernova is indicated by the arrow) and (b) with the supernova about 2 weeks after it was discovered. (Credit: Australian…
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from article Supernova
Supernova 1987A and its triple ring system 20 years after the explosion, as observed by the Hubble Space Telescope. The inner ring, which appears to be elliptical but is actually a circular equatorial ring, displays 30–40 bright spots, like pearls…
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from article Space biology
Aboard the International Space Station, NASA astronaut Steve Swanson harvests a crop of red romaine lettuce. This and other plant varieties have been grown in the station's Vegetable Production System (Veggie), for space biology experiments as well…
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from article Space biology
During a Space Shuttle Endeavour flight in 2008, astronauts Shane Kimbrough and Sandra Magnus experience weightlessness, further demonstrated by the floating apples, oranges, and pears. (Credit: NASA)
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from article Anemia
Hemoglobin molecule. (Copyright © McGraw-Hill Education)
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from article Anemia
Aplastic anemia. This low-power photomicrograph of the bone marrow exhibits only a small amount of hematopoiesis (the process by which the cellular elements of the blood are formed). (Copyright © McGraw-Hill Education)
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from article Anemia
Iron-deficiency anemia. Most red cells in this photomicrograph exhibit central pallor (arrow). Also present is a characteristic pencil-shaped cell (arrowhead). (Copyright © McGraw-Hill Education)
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from article Forest engineering
A harvesting machine removing selected trees in a thinning operation designed to enhance the growth of the trees that remain after the operation. The “processing head” is holding a horizontal tree stem that is being delimbed and processed into logs…
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from article Forest engineering
A well-engineered forest road and timber bridge in the Tongass National Forest in southeast Alaska. The bridge, designed to support heavy logging trucks, was used rather than a culvert to reduce erosion and protect water quality. (Photograph…
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from article Pomegranate
Pomegranate (Punica granatum). (Photo courtesy of the Agricultural Research Service Germplasm Repository)
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from article Agricultural machinery
A tractor pulling a multipurpose machine used for precision tillage and planting. (Credit: Scott Bauer/U.S. Department of Agriculture)
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from article Agricultural machinery
Agricultural aircraft applying a chemical pesticide on a field. (Credit: jupiterimages/Getty Images)
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from article Agricultural machinery
A combine harvester hopper filling up with corn kernels as the machine harvests the field. (Credit: Glow Images)
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from article Agricultural machinery
A harvester machine is used to drop tomatoes into a container. (Credit: Phil Schermeister/National Geographic RF/Getty Images)
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from article Saffron
Saffron (Crocus sativus) with its three red-colored stigmas. These distinctive stigmas (“saffron threads”) are dried to obtain the spice. (Photo copyright © Joanna Baron, used with permission)
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from article Messier Catalog
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from article Messier Catalog
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from article Deforestation
View of an area of deforestation in Central Kalimantan, Indonesia. In this case, the land is being cleared to develop areas for intensive rice production. (Credit: Australian National University)
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from article Deforestation
The relationship between forest and nonforest (other) land. Preservation of forest lands includes reforestation and natural regeneration. However, deforestation and natural events can lead to nonforest land. Afforestation (the act or process of…
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from article Deforestation
Natural forest areas (in hectares; 1 hectare = 2.47 acres) in various climatic domains (boreal/polar, temperate, subtropical, and tropical) from 1990 to 2015. The data are derived from the Global Forest Resources Assessment 2015 by the Food and…
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from article Deforestation
Former rainforest in northern Queensland, Australia, that was deforested in the early 1900s and is now used for pasture. (Credit: Rodney Keenan)
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from article Deforestation
Aerial view of deforestation in the Amazon region of Brazil. Clearing of trees in the Amazon rainforest has resulted in the elimination of natural resources and numerous species. (Credit: Luoman/Getty Images)
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from article Precession of equinoxes
Motion of the Earth's axis of rotation.
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from article Soil chemistry
Proper soil chemistry helps a green seedling to sprout out from the soil. Soil chemistry controls the availability of plant nutrients within the soil and thus influences plant growth. (Credit: amenic181/Shutterstock)
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from article Soil chemistry
Extensive chemical weathering can remove essential minerals and elements from soil. Typically, only the most insoluble compounds remain in the soil. For example, iron oxides may persist, imparting a reddish-brown color to the soil. (Credit: Stephen…
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from article Soil chemistry
Factors influencing the chemistry of a soil solution. (Credit: Based on an original illustration created by J. F. Hodson)
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from article Walnut
Pith of two species of Juglans: (left) butternut or white walnut (J. cinerea); (right) black walnut (J. nigra). (Photo by Bill Cook, Michigan State University; Bugwood.org)
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from article Walnut
Black walnut (Juglans nigra). (Photo by D. E. Herman, North Dakota State Soil Conservation Committee, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)
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from article Walnut
Fruits of black walnut (Juglans nigra). (Photo by Rob Routledge, Sault College, Sault Ste. Marie, Ontario, Canada; Bugwood.org)
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from article Walnut
English or Persian walnut (Juglans regia). (Photo by Milan Kořínek)
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from article Walnut
Kernel of English walnut (Juglans regia). (Photo by Piero Amorati, IC Croce, Casalecchio di Reno, Italy; Bugwood.org)
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from article Walnut
Walnut leaf showing symptoms of anthracnose (caused by the fungus Gnomonia leptostyla). (Photo by Pavel Šinkyřík, Czech Republic)
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from article Walnut
Canker disease (caused by the fungus Sirococcus clavigignenti-juglandacearum) on a butternut (Juglans cinerea). (Photo by Mike Ostry, U.S. Department of Agriculture Forest Service)
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from article Thrombosis
Organized thrombus in an artery with recanalization.
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from article Thrombosis
Organized thrombus in an artery with scar formation; the artery is completely occluded by the fibrotic mass.
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from article Clover
Red clover (Trifolium pratense). (Photo by Tom Heutte, U.S. Department of Agriculture Forest Service)
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from article Clover
White clover (Trifolium repens). (Photo by Pavel Šinkyřík)
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from article Clover
Crimson clover (Trifolium incarnatum). (Photo by Pavel Šinkyřík)
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from article Clover
White sweet clover (Melilotus albus). (Photo by Forest and Kim Starr)
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from article Clover
Leaves of clover affected by leaf spot, which is caused by the fungus Pseudopeziza trifolii. (Photo courtesy of the U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)
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from article Belladonna
Close-up view of the belladonna plant (Atropa belladonna), showing the leaves and berries, which are toxic. (Photo courtesy of Leo Michels)
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from article Lychee
Fruit and leaves of lychee (Litchi chinensis). (Photo courtesy of Forest and Kim Starr)
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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 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 Education)
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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 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 Education)
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from article Centaurus
Modern boundaries of the constellation Centaurus, the Centaur. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension representing…
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from article Astronomical imaging
Cross-sectional view of the physical structure of an MOS capacitor. Positive voltage (usually a few volts) applied to the metal layer creates a depletion region in the semiconductor.
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from article Astronomical imaging
CCD components and readout. (a) Accumulated photoelectrons in a 3 × 3 array of capacitors. Reading the array: (b) The bottom row shifts into the serial register; all remaining rows shift down by one pixel in the parallel register. (c–e) Serial…
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from article Astronomical imaging
Gate structure in a three-phase buried-channel CCD. (a) Two pixels, in cross section. (b) Electron potential pn junction. Collection and barrier potentials on the gates isolate the pixels from each other during an exposure. Overlapping gates produce…
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from article Astronomical imaging
Large CCD strategies. (a) Large monolithic detector with multiple serial registers and amplifiers (four, in this case). Read time is reduced by a factor equal to the number of amplifiers, and total charge transfer efficiency (CTE) is improved. (b)…
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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 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 Magellanic Clouds
Large Magellanic Cloud; the large red patch is the 30 Doradus nebula, one of the largest H II regions known. (Copyright © Australian Astronomical Observatory; photograph by David Malin from AAT plates)
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from article Magellanic Clouds
Small Magellanic Cloud. This image is composed from two images of the Digitized Sky Survey 2. (ESA/Hubble; Digitized Sky Survey 2)
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from article Magellanic Clouds
Large Magellanic Cloud. (Harvard Observatory photograph by P. Hodge)
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from article Magellanic Clouds
Giant gas cloud centered on 30 Doradus in the Large Magellanic Cloud. (Cerro Tololo Inter-American Observatory photograph by P. Hodge)
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from article Bluegrass
Kentucky bluegrass (Poa pratensis). (Photo courtesy of Forest and Kim Starr)
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from article Universe
An image from a computer simulation of large-scale structure formation in the universe, with vast filaments of relatively dense matter separated by even larger voids with low matter density. Each dot indicates an individual galaxy. (Credit: Max…
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from article Universe
The Hertzsprung-Russell (HR) diagram, which plots stars' temperatures (x axis) against their luminosities (y axis). Numerous examples of stars in the Milky Way are included in this sample diagram. (Credit: ESO)
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from article Universe
A mosaic of the central star-forming region of the Orion Nebula, otherwise known as M42. Here the emission from young stars (pointlike sources) lights up the surrounding gas, mostly composed of hydrogen atoms. (Credit: C. R. O'Dell and S. K. Wong,…
