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Native to Australia, White's Tree Frog grows up to 10 centimetres in length and is a popular household pet. In captivity, they have an average lifespan of 16 years. Its skin secretions contain caerins, a group of peptides with antibacterial and antiviral properties. Other peptides have been found to destroy HIV without harming healthy T-cells.

Photo credit: liquidGhoul
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Coloured smoke reveals a vortex of air created by the wing of an airplane, also known as wake turbulence or jetwash. This turbulence can be especially hazardous during the landing and take off phases of flight, where an aircraft's proximity to the ground makes a timely recovery from turbulence-induced problems unlikely.

Photo credit: NASA Langley Research Center
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A wickiup is a domed hut-like dwelling used by the semi-nomadic Native American tribes of southwestern North America. A wigwam is a similar structure but the term is used for those found in the northeastern part of America. Shown here is an Apache wickiup from 1903.

Photo credit: Edward S. Curtis
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The Nez Perce tribe lived in the northwestern United States, although they were known to head as far east as the Great Plains. They fought the last great battle between the U.S. government and an Indian nation as Chief Joseph and his warriors battled U.S. Cavalry troops over 1,600 miles (2,560 km) towards Canada before surrendering on October 5, 1877. This photograph was taken in 1910.

Photo credit: Edward S. Curtis
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Binoculars mounted to the signal bridge of the USS Harry S Truman show a MH-60 Knighthawk delivering supplies to the USS Dwight D. Eisenhower.

Photo credit: Airman Ricardo J. Reyes, U.S. Navy
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Hereford cattle are a widely-used breed in temperate areas, mainly for beef production. Originating from cool, moist Herefordshire, England, they have found great success, and indeed thrive, in a wide range of climates on nearly every continent. They are especially popular in the temperate parts of Australia and in the desert Southwestern United States.

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Montreal is the second-largest city in Canada. It sits in the south western corner of Quebec at the confluence of the Saint Lawrence and Ottawa Rivers. As in most parts of Quebec, French is the most common spoken language in the city, but there is a substantial anglophone population and many of the residents are bilingual. In 2005, it won the distinction of being chosen UNESCO's "World Book Capital City 2005–2006" due to its vibrant literary scene.

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In botany, a leaf is an above-ground plant organ specialized for photosynthesis. For this purpose, a leaf is typically flat (laminar) and thin, to expose the chloroplast containing cells (chlorenchyma tissue) to light over a broad area, and to allow light to penetrate fully into the tissues. This chart shows three aspects of leaf morphology: shape, margin (edge), and venation (arrangement of the veins).

Image credit: Debivort
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The Notre-Dame de Montréal Basilica in Montreal, Quebec, Canada is a prime example of Gothic Revival architecture. It was designed by James O'Donnell and was completed in 1879, at which time it was the largest church in North America. In 1982, Pope John Paul II raised the status of the church to basilica.

Photo credit: Diliff
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A rooster or cock is a male chicken. The term "rooster" is reputedly so used because the cock is said to roost over clutches of eggs to guard them. In fact, "roosting" is the action of perching aloft to sleep at night, and is done by both sexes. Roosters often are pictured in art as crowing at the break of dawn, and this is accurate. However, they will also crow during the rest of the day, and even sometimes on a bright moonlit night.

Photo credit: Fir0002/Didactohedron
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The White-breasted Nuthatch (Sitta carolinensis) is a small songbird found in North America. The adult birds are about 155 mm (6 in.) long. They forage on the trunk and large branches of trees, often descending head first. Their principal diet consists of insects and a few varieties of seeds. They often travel with small mixed flocks in winter.

Photo credit: mdf/Fir0002
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Schloss Neuschwanstein ("new swan stone castle") in southwest Bavaria is one of Germany's most popular tourist destinations. Construction was started by King Ludwig II and took 17 years. After his death in 1886, the castle was opened to the public. During World War II, many valuable items (all stolen) were stored at the castle, destined for Adolf Hitler's personal collection.

Photo credit: Softeis
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San Francisco International Airport (IATA: SFO) opened on May 7, 1927 on 150 acres (607,000 m²) of cow pasture leased from prominent local landowner Ogden L. Mills, and was named Mills Field Municipal Airport. During the economic boom of the 1990s and the dot com boom, SFO became the 6th busiest international airport in the world. However, since the boom times ended, it has fallen back out of the top twenty.

Photo credit: Andrew Choy
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Uncle Sam is a national personification of the United States dating from the War of 1812. During World War I and World War II, Uncle Sam's image was used for military recruitment in this poster. The poster uses an artistic trick: if the pupils are drawn exactly centered in the eyes of a portrait, this gives an impression that the portrait "looks back" at the viewer wherever the viewer stands.

Image credit: James Montgomery Flagg
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Vaduz /vaˈduːts/ is the capital of the principality of Liechtenstein. It is the seat of the national parliament. The town has about 5,000 inhabitants, most of whom are Roman Catholic, and is located along the Rhine. It is thought to have been founded in the 13th century by the Counts of Werdenberg. In 1322 there is mention of the castle which was sacked by the Swiss in 1499.

Photo credit: Mschlindwein
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The International Space Station is located in a low Earth orbit, approximately 360 km (220 miles) high. The station has a capacity for a crew of three and there have always been at least two people on board. It has been visited by astronauts from a large number of countries and was also the destination of the first three space tourists.

Photo credit: NASA
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Photo credit: Roger McLassus
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The Queen Elizabeth II Great Court of the British Museum is a covered square designed by the architects Foster and Partners. It opened in December 2000 and is the largest covered square in Europe. The roof is a glass and steel construction with 1,656 pairs of uniquely shaped glass panes. At the centre of the Great Court is the Reading Room, which is open to any member of the public who wishes to read there.

Photo credit: Andrew Dunn
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Charlotte Corday was a poor French aristocrat who supported the Girondists during the French Revolution. She single-handedly assassinated Jean-Paul Marat, a Jacobin journalist, with a knife in 1793. Although she was beheaded four days afterwards and the Reign of Terror continued for another year, she was later seen as a heroine who gave her life to rid her country of a monster. The assassination is depicted in this 1860 painting.

Artist: Paul-Jacques-Aimé Baudry
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On January 28, 1986, a ruptured O-ring in the right solid rocket booster caused the Space Shuttle Challenger to explode soon after launch. This photograph shows the main engines and solid rocket booster exhaust plumes entwined around a ball of gas from the external tank. Because shuttle launches had become almost routine after fifty successful missions, those watching the shuttle launch in person and on television found the sight of the break up especially shocking and difficult to believe until NASA confirmed the accident.

Photo credit: NASA
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Lava tubes are natural conduits through which lava travels beneath the surface of a lava flow. They can be actively draining lava from a source, or can be extinct, meaning the lava flow has ceased and the rock has cooled and left a long, cave-like channel. Tubes form in one of two ways: by the crusting over of lava channels and from Pahoehoe flows where the lava is moving under the surface.

Photo credit: Michael Oswald
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Cuttlefish are small relatives of squids and nautilus, sometimes called the chameleon of the sea because of their remarkable ability to rapidly alter their skin color at will. They have an internal shell, large eyes, and eight arms and two tentacles furnished with denticulated suckers, by means of which they secure their prey. There are 119 species of cuttlefish.

Photo credit: Diliff
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Zuikaku was an aircraft carrier of the Imperial Japanese Navy. Her planes took part in the attack on Pearl Harbor that started the Pacific War, and she fought in several of the most important naval battles of the war. Sustaining heavy damage in the battle off Cape Engaño, the crew lowered the flag (shown here; note the sharp list to port) and attempted to abandon ship, but were unable to do so before she capsized.

Photo credit: Kazutoshi Hando
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Sea anemones are water-dwelling, filter feeding animals, closely related to coral and jellyfish. They are composed of a small sac, attached to the bottom by an adhesive foot, with a column shaped body ending in an oral disc which contains the mouth, surrounded by the tentacles with stinging cells. The tentacles contain neurotoxins, which serve to paralyze and capture the prey, which is then moved by the tentacles to the mouth for digestion inside a central cavity. Anemones tend to stay in the same spot unless they are unhappy with that location, or a predator is attacking them. In the case of an attack, anemones can uproot themselves and swim away to a new location.

Image credit: Ernst Haeckel
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A rainbow is an optical and meteorological phenomenon that causes a nearly continuous spectrum of light to appear in the sky when the Sun shines onto droplets of moisture in the Earth's atmosphere. A rainbow does not actually exist at a location in the sky, but rather is an optical illusion whose apparent position depends on the observer's location. Even though a rainbow spans a continuous spectrum of colours, traditionally the full sequence of colours is most commonly cited as red, orange, yellow, green, blue, indigo, and violet. Indigo is usually included despite the poor ability of humans to distinguish colours in the blue portion of the visual spectrum.

Photo credit: Wing-Chi Poon
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Loch Lomond is a Scottish loch located in both the western lowlands of Central Scotland and the southern Highlands. Its surface area is the largest of the lochs, and is second biggest after Loch Ness in terms of water volume in Great Britain. The loch famously features in Andrew Lang's verse, The Bonnie Banks o' Loch Lomond, published around 1876, the chorus of which is well known.

Photo credit: Abubakr Hussain et al
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Carbon nanotubes are cylindrical carbon molecules with novel properties that make them potentially useful in a wide variety of applications. They exhibit extraordinary strength and unique electrical properties, and are efficient conductors of heat. Their name is derived from their size, since the diameter of a nanotube is on the order of a few nanometers (approximately 50,000 times smaller than the width of a human hair), while they can be up to several micrometers in length.

Photo credit: Michael Ströck
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The Liverpool Metropolitan Cathedral is a Roman Catholic cathedral in Liverpool, England. The church was consecrated in 1967 and was designed by Sir Frederick Gibberd. Commonly called "Paddy's Wigwam" because of its largely Irish Catholic congregation and its general resemblance to a Native American teepee, the cathedral has the largest stained glass window in the world.

Photo credit: Chowells
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