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Project

1-Wire Weather Station

The weather station in this project is quite basic, measuring only temperature, pressure, and humidity, but it may be easily expanded to measure other weather components, such as wind speed and rainfall. The design is based on using a series of…

Project

3D Skull Candy Mold

Whether preparing for Halloween or just a regular day, you can make skull-shaped edibles from this project's 3D candy mold. Like many molds, this one is a hollow container into which you can pour water or hot liquids, such as gelatin, chocolate, or…

Project

3x3x3 LED Cube

LEDs (light-emitting diodes) are rectifying semiconductor devices that convert electrical energy into electromagnetic radiation. You can use these devices to create a 3-dimensional light display. LED cubes require some care and good soldering skills…

Project

Chatbot, an Artificially Intelligent Microcontroller

The term "Chatbot" is used for a computer or computer program that is made to emulate some form of human intelligence through conversation. In this project, you will learn how easy it is to make a specific microcontroller—an Arduino™ Uno—seem as…

Project

Text-Controlled RGB LED

A red, green, and blue (RGB) light-emitting diode (LED) is a useful electronic component that can produce visible light in a variety of colors. This is done by varying the intensity of the light output of the three different color LED elements (red,…

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from article Tomato

Tomato affected by anthracnose (caused by the fungus Colletotrichum phomoides). (Credit: U.S. Department of Agriculture Cooperative Extension Slide Series, Clemson University)

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from article Tomato

Tomatoes showing blossom-end rot. (Credit: Mary Ann Hansen, Virginia Polytechnic Institute and State University)

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from article Pine nut

Pine nuts in their hard shell (Mexican piñon pine, Pinus cembroides). (Photo by Steve Hurst, U.S. Department of Agriculture–Natural Resources Conservation Service PLANTS Database)

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from article Pine nut

Cone containing pine nuts (stone pine, Pinus pinea). (Photo by Vito Buono, Bari, Italy)

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from article Ctenothrissiformes

A Cretaceous ctenothrissiform fossil, Ctenothrissa sp. (order Ctenothrissiformes), on a limestone matrix found in Lebanon. Size: 90 mm (3.5 in.). (Photo courtesy of The Virtual Fossil Museum)

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from article Food science

Food scientist examining a tomato. (Credit: Adam Gault/Age Fotostock)

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from article Acari

Parasitiformes body plan. Lateral view of a predatory adult female Mesostigmata showing major body regions and important structures. Scale bar = 0.1 mm (0.004 in.). (Scanning electron micrograph by D. E. Walter)

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from article Acari

Acariformes body plan. (a) Adult female Oribatida (Sarcoptiformes) in lateral view showing major body regions and important structures. (b) Hexapod larva (Trombidiformes): dorsal view of a chigger, a parasite of vertebrates. (c) Octopod deutonymph…

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from article Poplar

Quaking aspen (Populus tremuloides). (Photo courtesy of North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)

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from article Poplar

Common poplar species. (a) Quaking aspen (P. tremuloides); leaf scar with an axial bud, leaf, and twig. (b) Bigtooth aspen (P. grandidentata); leaf, terminal bud, and twig. (c) Cottonwood poplar (P. deltoides); leaf, leaf scar, terminal bud, and…

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from article Haplosporida

Spore of Urosporidium fuliginosum.

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from article Haplosporida

Stages in the development of Icthyosporidium giganteum.

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from article Transmission lines

Two common transmission lines for communication. (a) Coaxial cable. (b) Strip line.

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from article Transmission lines

Equivalent circuit that represents three sections of a lossless transmission line. Each section is of length Δz, and has an inductor (L) and capacitor (C). Voltages (V ) and currents (I ), and their differences (ΔV and ΔI ) between successive…

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from article Transmission lines

Signal detection on an oscilloscope. (a) Oscilloscope pictures of voltage pulses at three locations, z1, z2, and z3, on a transmission line, successively more distant from the signal generator. (b) Oscilloscope pictures of a periodic voltage sine…

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from article Transmission lines

Transmission line with characteristic impedance Zc, terminated in a load impedance ZL. A change of coordinate system (from z to ζ) is indicated.

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from article Transmission lines

Envelope of the voltage standing wave consisting of a wave propagating from z = −∞ and being reflected at z = 0. The wavelength, λ, and the maximum and minimum voltages, Vmax and Vmin , are indicated.

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from article Transmission lines

Two waveguides, with conventional coordinates. (a) Rectangular waveguide. (b) Cylindrical waveguide.

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from article Transmission lines

Dispersion curve for a rectangular waveguide of width a, showing relationship between the propagation constant, β, and the angular frequency, ω. Here, n specifies the mode of propagation, and c is the speed of light.

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from article Transmission lines

Equivalent circuit of a power transmission line. The single-phase circuit is used to represent balanced three-phase lines. Here, R and X are the resistance and reactance (at the operational frequency), and C is the capacitance of the entire…

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from article Urodela

A typical member of the order Urodela: the longtail salamander (Eurycea longicauda). (Credit: Ryan Hagerty/U.S. Fish and Wildlife Service)

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from article Urodela

Southern dwarf siren (Pseudobranchus axanthus), which has undergone limb degeneration and retains only tiny forelimbs. (Credit: U.S. Geological Survey)

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from article Urodela

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from article Urodela

California tiger salamander (Ambystoma californiense). (Credit: John Cleckler/U.S. Fish and Wildlife Service)

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from article Urodela

The two-toed amphiuma salamander (Amphiuma means). (Credit: Southeast Ecological Center, U.S. Geological Survey)

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from article Urodela

The northern red salamander (Pseudotriton ruber ruber) is a member of the family Plethodontidae. (Credit: Alicia Lafever/U.S. National Park Service)

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from article Chamois

Alpine chamois (Rupicapra rupicapra). (Photograph courtesy of Brent Huffman/Ultimate Ungulate Images)

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from article Chicxulub impact crater

Bouguer gravity anomaly map over the Chicxulub impact crater. The coastline is designated by a thin white line, cenotes (natural pits) and sinkholes are designated by black dots, and the city of Mérida and the town of Chicxulub Puerto are designated…

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from article Chicxulub impact crater

Seismic line imaging of what lies beneath the seafloor, showing the Chicxulub impact crater. The crater includes many faults that can be grouped into an exterior ring fault, a series of outer ring faults, and a series of inner ring faults. Within…

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from article Amniota

Basic types of vertebrate eggs.

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from article Amniota

Embryo developing in amniote eggs.

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from article Osage orange

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from article Mecoptera

Male scorpion fly (Panorpa), order Mecoptera.

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from article Magnolia

Flowers and leaves of the southern magnolia (Magnolia grandiflora). (Photo courtesy of Forest and Kim Starr)

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from article Ursa Minor

Modern boundaries of the constellation Ursa Minor, the Little Bear. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension…

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from article Hackberry

Hackberry (Celtis occidentalis). (Credit: North Dakota State Soil Conservation Committee, USDA–NRCS PLANTS Database)

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from article Venus

Venus compared to Earth in size. Note that the image of Venus at left does not include the planet's thick, opaque atmosphere. The image was obtained by the Magellan spacecraft that orbited Venus from 1990 to 1994. Magellan used cloud-penetrating…

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from article Venus

Venus viewed in visible light by the Galileo spacecraft during a 1990 gravity assist flyby on the probe's ultimate journey to Jupiter. (Credit: NASA)

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from article Venus

Global Venus clouds, as viewed in the ultraviolet from Venus Express. These features can be used to track winds and atmospheric motion at the cloud tops. Convection clouds can be seen near the equator (top of image), whereas streaky brighter clouds…

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from article Venus

Inhomogeneities in the total thickness of the clouds between 48 and 70 km (30 and 43 mi) show up in the near-infrared. These clouds, seen only at night, are backlit from the hot atmosphere below it (similar to a Chinese lantern), where bright…

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from article Venus

Perspective view of the southern boundary of Laksmi Planum, a plateau 2.5–4.0 km (1.5–2.5 mi) high. (Credit: NASA/JPL)

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from article Venus

Magellan image of the central and northern parts of the highland region Ovda Regio (north at top). Ridges running approximately east-west (horizontally) have been interpreted as resulting from crustal shortening (compression). Ridges are cut by…

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from article Venus

Perspective view of a portion of the Western Eistla Regio, with a rift valley in the foreground and the volcanoes Gula Mons (right) and Sif Mons (left) on the horizon. (Credit: NASA/JPL)

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from article Venus

Sapas Mons, one of several large volcanic edifices that compose the broad equatorial rise known as Alta Regio. (Credit: NASA/JPL)

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from article Venus

Computer-simulated perspective view, based on data from Magellan spacecraft, showing three impact craters in the northwestern portion of Lavinia Planitia with diameters ranging from 37 to 63 km (23 to 39 mi). (Credit: NASA/JPL)

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from article Crosstalk

Crosstalk in a space-division system. Z1, Z2, Z3, and Z4 designate impedances.

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from article Computer-aided circuit design

Four phases in creating a microelectronic chip. (a) Design. (b) Fabrication. (c) Testing. (d) Packaging. (After G. De Micheli, Synthesis and Optimization of Digital Circuits, McGraw-Hill, 1994)

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from article Computer-aided circuit design

Three abstraction levels of a circuit representation. (a) Architectural level. (b) Logic level. (c) Geometrical level. (After G. De Micheli, Synthesis and Optimization of Digital Circuits, McGraw-Hill, 1994)

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from article Saccopharyngiformes

Pelican or gulper eel (Eurypharynx pelecanoides), a member of the order Saccopharyngiformes. [Photo by Alexei Orlov, Russian Federal Research Institute of Fisheries and Oceanography (VNIRO), Moscow, Russia]

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from article Computer security

Applications such as power generation, stock trading, airplane navigation, and medical care have become so dependent on computing that loss of availability becomes a serious threat to life or society. Even on a less dramatic level, people have…

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from article Computer security

Smartphone with fingerprint identification. (Credit: Anatoliy Babiy/Getty Images)

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from article Rosemary

Leaves of rosemary (Rosmarinus officinalis). (Photograph courtesy of Forest and Kim Starr)

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from article Squash

Zucchini (Cucurbita pepo), a type of summer squash, with flowers. (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)

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from article Squash

Crookneck squash (Cucurbita moschata). (Credit: Howard F. Schwartz, Colorado State University/www.Bugwood.org)

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from article Squash

Delicata squash (Cucurbita pepo), a variety of winter squash. (Credit: Shaun Case)

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from article Squash

Leaves of Cucurbita pepo infected by a squash mosaic virus. (Credit: William M. Brown, Jr./www.Bugwood.org)

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from article Astronomy

A photograph of the Milky Way in the night sky over the European Southern Observatory's 3.6-metre telescope, at right, at the La Silla Observatory in northern Chile. [Credit: ESO/B. Tafreshi (twanight.org)]

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from article Astronomy

An artist’s impression of the exoplanet GJ 504, a world several times the size of Jupiter and anticipated to have a magenta color, still glowing from its initial formation. (Credit: NASA's Goddard Space Flight Center/S. Wiessinger)

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from article Astronomy

The Hubble Space Telescope in orbit above Earth. (Credit: NASA)

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from article Wine

Stainless steel fermentation tanks (fermenters). (Credit: Granger Wootz/Blend Images LLC)

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from article Wine

Dark-skinned grapes ready for harvest in France. (Credit: Getty Images/RooM RF)

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from article Programmable controller

Functional architecture of a typical high-performance single-chip microcontroller used for control and signal processing. (National Semiconductor Corp.)

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from article Orbital motion

Orbital motion in a plane, in the shape of an ellipse, with the primary body at the focus F.

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from article Orbital motion

Orbit oriented in space with respect to a fundamental plane, in this case the celestial equator.

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from article Llama

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from article Platypus

Platypus, a primitive aquatic mammal. (Photograph by Paddy Ryan/Ryan Photographic)

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from article Cashew

Cashew (Anacardium occidentale). The cashew nut is contained in a hard shell at the bottom of the fruit (cashew apple). (Credit: Laura Lartigue/U.S. Agency for International Development, Guinea)

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from article Biological insect control

The emerald ash borer (Agrilus planipennis) is an invasive pest insect that damages ash tree species in North America and Europe. Researchers are searching for natural enemies against the borer in its native range (Asia) to use as biological control…

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from article Acanthometrida

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from article Winged bean

Winged bean (Psophocarpus tetragonolobus). (Photo by Forest and Kim Starr)

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from article Sarcodina

Some shelled Lobosia. (a) Arcella, seen from above; (b) sporulating into numerous ameboid young; (c) in binary fission, with the two nuclei in mitosis with polar caps; part of the cytoplasm exudes from the pylome and secretes a new shell. (d)…

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from article Paleocopa

Paleocopa. (a) Ogmoopsis nodulifera, left valve; from the Ordovician of Sweden. (b) Eurychilina subradiata, right valve showing wide complete frill; Ordovician of Minnesota. (c) Sulcicuneus porrectinatium, male and female carapaces; Devonian of…

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from article Garlic

Bulbs of garlic (Allium sativum). (Credit: Forest and Kim Starr)

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from article Coriander

Coriander seeds (Coriandrum sativum). (Photograph courtesy of Steve Hurst, USDA–NRCS PLANTS Database)

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from article Podocopida

Candona suburbana, an ostracod of the Cypridoidea. Animals with right valves removed. (a) Female; note dimorphic differences in carapace outline and first leg. (b) Male with hemipenis rotated, folded, and retracted; part of the body wall is removed…

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from article Podocopida

Limnocythere sanctipatricii, a podocopid ostracod of the Cytheroidea. (a) Male with left valve removed; the paired hemipenes occupy much of the space at the rear of the carapace. (b) Male left “brush-shaped organ,” an unusual structure found only…

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from article Podocopida

Darwinula stevensoni, a podocopid ostracod of the Darwinuloidea. In this parthenogenetic species, eggs and young are protected in a brood space behind the body. (After R. C. Moore, ed., Treatise on Invertebrate Paleontology, pt. Q, 1961)

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from article Social mammals

Meerkats (Suricata suricatta) are notable social mammals. Here, they are looking for danger outside of their den. (Credit: Alta Oosthuizen/Shutterstock)

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from article Social mammals

An adult female African lion (Panthera leo) nurses four cubs. The early ingestive behavior (nursing) of mammals has a high degree of social significance. (Credit: Glow Images)

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from article Social mammals

Mexican spider monkeys (Ateles geoffroyi vellerosus) are primates that display many examples of social behavior and organization. (Credit: Oksana Kunka/123RF)

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from article Strawberry

June-bearing strawberries (Fragaria × ananassa), which are produced in early summer. (Credit: Kimberly Lewers/Agricultural Research Service, United States Department of Agriculture)

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from article Strawberry

Botrytis cinerea fungal sporulation on a ripe strawberry. (Credit: Scott Bauer/Agricultural Research Service, United States Department of Agriculture)

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from article Concentricycloidea

Aboral surface of a sea daisy.

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from article Concentricycloidea

Underside of a sea daisy, which is occupied by a large oral opening.

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from article Ultrawideband (UWB) systems

Relationships between various UWB systems.

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from article Ultrawideband (UWB) systems

Frequency-modulated continuous-wave (FMCW) swept-frequency signaling. (a) Plot of the amplitude of the continuous wave against time, showing it gradually changing frequency. (b) Frequency-versus-time plot.

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from article Ultrawideband (UWB) systems