Leonardo Fibonacci

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Fibonacci From Wikipedia, the free encyclopedia

Leonardo of Pisa (c. 1170 – c. 1250), also known as Leonardo Pisano, Leonardo Bonacci, Leonardo Fibonacci, or, most commonly, simply Fibonacci, was an Italian mathematician, considered by some "the most talented mathematician of the Middle Ages"

In his work Liber Abaci, Fibonacci introduces the so-called modus Indorum (method of the Indians), today known as Hindu-Arabic numerals (Sigler 2003; Grimm 1973). The book advocated numeration with the digits 0–9 and place value. The book showed the practical importance of the new numeral system, using lattice multiplication and Egyptian fractions, by applying it to commercial bookkeeping, conversion of weights and measures, the calculation of interest, money-changing, and other applications. The book was well received throughout educated Europe and had a profound impact on European thought. Nevertheless, the use of decimal numerals did not become widespread until much later.

Liber Abaci also posed, and solved, a problem involving the growth of a hypothetical population of rabbits based on idealized assumptions. The solution, generation by generation, was a sequence of numbers later known as Fibonacci numbers. The number sequence was known to Indian mathematicians as early as the 6th century, but it was Fibonacci's Liber Abaci that introduced it to the West.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article, Fibonacci

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Gold Nanoparticles

Caption: False color scanning electron micrograph (250,000 times magnification) showing the gold nanoparticles created by NIST and the National Cancer Institute's Nanotechnology Characterization Laboratory for use as reference standards in biomedical research laboratories. Credit: Andras Vladar, NIST. Usage Restrictions: None.

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Colloidal gold From Wikipedia, the free encyclopedia

Colloidal gold, also known as "nanogold", is a suspension (or colloid) of sub-micrometre-sized particles of gold in a fluid — usually water. The liquid is usually either an intense red colour (for particles less than 100 nm), or a dirty yellowish colour (for larger particles). The nanoparticles themselves can come in a variety of shapes. Spheres, rods, cubes, and caps are some of the more frequently observed ones.

Known since ancient times, the synthesis of colloidal gold was originally used as a method of staining glass. Modern scientific evaluation of colloidal gold did not begin until Michael Faraday's work of the 1850s. Due to the unique optical, electronic, and molecular-recognition properties of gold nanoparticles, they are the subject of substantial research, with applications in a wide variety of areas, including electronics, nanotechnology, and the synthesis of novel materials with unique properties.

Generally, gold nanoparticles are produced in a liquid ("liquid chemical methods") by reduction of hydrogen tetrachloroaurate (HAuCl4), although more advanced and precise methods do exist. After dissolving HAuCl4, the solution is rapidly stirred while a reducing agent is added. This causes Au3+ ions to reduce to un-ionized gold atoms. As more and more of these gold atoms form, the solution becomes supersaturated, and gold gradually starts to precipitate in the form of sub-nanometer particles. The rest of the gold atoms that form stick to the existing particles, and, if the solution is stirred vigorously enough, the particles will be fairly uniform in size.

To prevent the particles from aggregating, some sort of stabilizing agent that sticks to the nanoparticle surface is usually added. They can be functionalized with various organic ligands to create organic-inorganic hybrids with advanced functionality.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article, Colloidal gold

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Johannes Kepler

Johannes Kepler German mathematician and optician. Copy of a lost original of 1610 in the Benedictine monastery in Krems. This image is a faithful reproduction of a two-dimensional work of art and thus not copyrightable in itself in the U.S. as per Bridgeman Art Library v. Corel Corp.; the same is also true in many other countries. The original two-dimensional work shown in this image is free content because: This image (or other media file) is in the public domain because its copyright has expired. This applies to the United States, where Works published prior to 1978 were copyright protected for a maximum of 75 years. See Circular 1 "COPYRIGHT BASICS" from the U.S. Copyright Office. Works published before 1923 are now in the public domain

and also in countries that figure copyright from the date of death of the artist (post mortem auctoris) and that most commonly run for a period of 50 to 70 years from that date. High Resolution Image‎ (1,500 × 2,060 pixels, file size: 424 KB, MIME type: image/jpeg)

Johannes Kepler: His Life, His Laws and Times

Johannes Kepler was born at 2:30 PM on December 27, 1571, in Weil der Stadt, Württemburg, in the Holy Roman Empire of German Nationality. He was a sickly child and his parents were poor. But his evident intelligence earned him a scholarship to the University of Tübingen to study for the Lutheran ministry. There he was introduced to the ideas of Copernicus and delighted in them. In 1596, while a mathematics teacher in Graz, he wrote the first outspoken defense of the Copernican system, the Mysterium Cosmographicum.

Kepler's family was Lutheran and he adhered to the Augsburg Confession a defining document for Lutheranism. However, he did not adhere to the Lutheran position on the real presence and refused to sign the Formula of Concord. Because of his refusal he was excluded from the sacrament in the Lutheran church. This and his refusal to convert to Catholicism left him alienated by both the Lutherans and the Catholics. Thus he had no refuge during the Thirty-Years War.

Kepler was forced to leave his teaching post at Graz due to the counter Reformation because he was Lutheran and moved to Prague to work with the renowned Danish astronomer, Tycho Brahe. He inherited Tycho's post as Imperial Mathematician when Tycho died in 1601. Using the precise data that Tycho had collected, Kepler discovered that the orbit of Mars was an ellipse. In 1609 he published Astronomia Nova, delineating his discoveries, which are now called Kepler's first two laws of planetary motion. And what is just as important about this work, "it is the first published account wherein a scientist documents how he has coped with the multitude of imperfect data to forge a theory of surpassing accuracy" (O. Gingerich in forward to Johannes Kepler New Astronomy translated by W. Donahue, Cambridge Univ Press, 1992), a fundamental law of nature. Today we call this the scientific method.

In 1612 Lutherans were forced out of Prague, so Kepler moved on to Linz. His wife and two sons had recently died. He remarried happily, but had many personal and financial troubles. Two infant daughters died and Kepler had to return to Württemburg where he successfully defended his mother against charges of witchcraft. In 1619 he published Harmonices Mundi, in which he describes his "third law."

In spite of more forced relocations, Kepler published the seven-volume Epitome Astronomiae in 1621. This was his most influential work and discussed all of heliocentric astronomy in a systematic way. He then went on to complete the Rudolphine Tables that Tycho had started long ago. These included calculations using logarithms, which he developed, and provided perpetual tables for calculating planetary positions for any past or future date. Kepler used the tables to predict a pair of transits by Mercury and Venus of the Sun, although he did not live to witness the events.

Johannes Kepler died in Regensburg in 1630, while on a journey from his home in Sagan to collect a debt. His grave was demolished within two years because of the Thirty Years War. Frail of body, but robust in mind and spirit, Kepler was scrupulously honest to the data. Johannes Kepler: His Life, His Laws and Times

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NASA - Hypersonic X-43A Scramjet Aircraft

This image (captured from animation video) illustrates the X-43A research vehicle alone after separation from the Pegasus booster. (LaRC Photo # EL-2000-00531) High Resolution Image

The X-43A was a small experimental research aircraft designed to flight-demonstrate the technology of airframe-integrated supersonic ramjet or "scramjet" propulsion at hypersonic speeds above Mach 5, or five times the speed of sound. Its scramjet engine is an air-breathing engine in which the airflow through the engine remains supersonic.

Still Images, Audio Files and Video

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It's Official. X-43A Raises the Bar to Mach 9.6

Guinness World Records recognized NASA's X-43A scramjet with a new world speed record for a jet-powered aircraft - Mach 9.6, or nearly 7,000 mph. The X-43A set the new mark and broke its own world record on its third and final flight on Nov. 16, 2004.

In March 2004, the X-43A set the previous record of Mach 6.8 (nearly 5,000 mph). The fastest air-breathing, manned vehicle, the U.S. Air Force SR-71, achieved slightly more than Mach 3.2. The X-43A more than doubled, then tripled, the top speed of the jet-powered SR-71.

"Mach Number" was named after the Austrian physicist Ernst Mach. Mach 1 is the speed of sound, which is approximately 760 miles per hour at sea level. An airplane flying less than Mach 1 is traveling at subsonic speeds, faster than Mach 1 would be supersonic speeds and Mach 2 would be twice the speed of sound. Hypersonic X-43A Takes Flight

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Quantum Computers superconducting circuit

Optical micrograph showing an "artificial atom" made with a superconducting circuit. The red arrow points to the heart of the qubit -- the Josephson junction device that might be used in a future quantum computer to represent a 1, 0, or both values at once. Credit: Ray Simmonds/NIST High Resolution Image Use of NIST Information: These World Wide Web pages are provided as a public service by the National Institute of Standards and Technology (NIST). With the exception of material marked as copyrighted, information presented on these pages is considered public information and may be distributed or copied.

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If they can be built, quantum computers—relying on the rules of quantum mechanics, nature’s instruction book for the smallest particles of matter—someday might be used for applications such as fast and efficient code breaking, optimizing complex systems such as airline schedules, much faster database searching and solving of complex mathematical problems, and even the development of novel products such as fraud-proof digital signatures.

Superconducting circuits are one of a number of possible technologies for storing and processing data in quantum computers that are being investigated for producing qubits at NIST, UCSB (University of California, Santa Barbara) and elsewhere around the world. Research using real atoms as qubits has advanced more rapidly thus far, but superconducting circuits offer the advantage of being easily manufactured, easily connected to each other, easily connected to existing integrated circuit technology, and mass producible using semiconductor fabrication techniques. A single superconducting qubit is about the width of a human hair. Two qubits can be fabricated on a single silicon microchip, which sits in a shielded box about 1 cubic inch in size. Scientists Entice Superconducting Devices To Act Like Pairs of Atoms

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Robert Goddard Space Pioneer

Robert Goddard: Pioneer: Robert Goddard, a pioneer in rocket development, received patents for a multi-stage rocket and liquid propellants in 1914 and published a paper describing how to reach extreme altitudes six years later. That paper, "A Method of Reaching Extreme Altitudes," detailed methods for raising weather-recording instruments higher than what could be achieved by balloons and explained the mathematical theories of rocket propulsion.High Resolution Image (2.2 MB)

The paper, which was published by the Smithsonian Institution, also discussed the possibility of a rocket reaching the moon -- a position for which the press ridiculed Goddard. Yet several copies of the report found their way to Europe, and by 1927, the German Rocket Society was established, and the German Army began its rocket program in 1931.

Goddard, meanwhile, continued his work. By 1926, he had constructed and tested the first rocket using liquid fuel. Goddard's work largely anticipated in technical detail the later German V-2 missiles, including gyroscopic control, steering by means of vanes in the jet stream of the rocket motor, gimbal-steering, power-driven fuel pumps and other devices.

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methicillin resistant Staphylococcus aureus (MRSA) bacteria

Magnified 20,000X, this colorized scanning electron micrograph (SEM) depicts a grouping of methicillin resistant Staphylococcus aureus (MRSA) bacteria. See PHIL 617 for a black and white view of this image. These S. aureus bacteria are methicillin-resistant, and are from one of the first isolates in the U.S. that showed increased resistance to vancomycin as well.

Note the increase in cell wall material seen as clumps on the organisms’ surface. Retrieve uncompressed archival TIFF version (10.77 megabytes)

Content Providers(s): CDC/ Jim Biddle. Creation Date: 1998. Photo Credit: Janice Carr. Links:

CDC – Div. of Healthcare Quality Promotion (DHQP) MRSA - methicillin resistant Staphylococcus aureus

Copyright Restrictions: None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited.

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The Crab Nebula

In the year 1054 A.D., Chinese astronomers were startled by the appearance of a new star that was so bright that it was visible in broad daylight for several weeks. Located about 6,500 light-years from Earth, the Crab Nebula is the remnant of a star that began its life with about 10 times the mass of our sun. Its life ended on July 4, 1054 when it exploded as a supernova. High Resolution Image (1.66 MB)

Resembling an abstract painting by Jackson Pollack, the image shows ragged shards of gas that are expanding away from the explosion site at over 3 million miles per hour. The core of the star has survived the explosion as a pulsar, a neutron star that spins on its axis 30 times a second. It heats its surroundings, creating the ghostly diffuse bluish-green glowing gas cloud in its vicinity. The colorful network of filaments is the material from the outer layers of the star that was expelled during the explosion. The various colors in the picture arise from different chemical elements in the expanding gas, including hydrogen (orange), nitrogen (red), sulfur (pink), and oxygen (green). The shades of color represent variations in the temperature and density of the gas, as well as changes in the elemental composition.

Image Credit: NASA, Kris Davidson (U. Minn.), William P. Blair (JHU), Robert A. Fesen (Dartmouth), Alan Uomoto (JHU), Gordon M. MacAlpine (U. Mich.), and Richard B.C. Henry (U. Okla.)

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Sputnik: 50th Anniversary

Photography: Photographs available from this web site (NASA History) are not protected by copyright unless noted. If not copyrighted, photographs may be reproduced and distributed without further permission from NASA. If the NASA material is to be used for commercial purposes, especially including advertisements, it must not explicitly or implicitly convey NASA's endorsement of commercial goods or services. High Resolution Image (~7MB). Telemetry from Sputnik I as it passed overhead.

Sputnik and The Dawn of the Space Age, History changed on October 4, 1957, when the Soviet Union successfully launched Sputnik I. The world's first artificial satellite was about the size of a basketball, weighed only 183 pounds, and took about 98 minutes to orbit the Earth on its elliptical path. That launch ushered in new political, military, technological, and scientific developments. While the Sputnik launch was a single event, it marked the start of the space age and the U.S.-U.S.S.R space race.

The story begins in 1952, when the International Council of Scientific Unions decided to establish July 1, 1957, to December 31, 1958, as the International Geophysical Year (IGY) because the scientists knew that the cycles of solar activity would be at a high point then. In October 1954, the council adopted a resolution calling for artificial satellites to be launched during the IGY to map the Earth's surface.

In July 1955, the White House announced plans to launch an Earth-orbiting satellite for the IGY and solicited proposals from various Government research agencies to undertake development. In September 1955, the Naval Research Laboratory's Vanguard proposal was chosen to represent the U.S. during the IGY.

The Sputnik launch changed everything. As a technical achievement, Sputnik caught the world's attention and the American public off-guard. Its size was more impressive than Vanguard's intended 3.5-pound payload. In addition, the public feared that the Soviets' ability to launch satellites also translated into the capability to launch ballistic missiles that could carry nuclear weapons from Europe to the U.S. Then the Soviets struck again; on November 3, Sputnik II was launched, carrying a much heavier payload, including a dog named Laika.

Immediately after the Sputnik I launch in October, the U.S. Defense Department responded to the political furor by approving funding for another U.S. satellite project. As a simultaneous alternative to Vanguard, Wernher von Braun and his Army Redstone Arsenal team began work on the Explorer project.

On January 31, 1958, the tide changed, when the United States successfully launched Explorer I. This satellite carried a small scientific payload that eventually discovered the magnetic radiation belts around the Earth, named after principal investigator James Van Allen. The Explorer program continued as a successful ongoing series of lightweight, scientifically useful spacecraft.

The Sputnik launch also led directly to the creation of National Aeronautics and Space Administration (NASA). In July 1958, Congress passed the National Aeronautics and Space Act (commonly called the "Space Act"), which created NASA as of October 1, 1958 from the National Advisory Committee for Aeronautics (NACA) and other government agencies.

RELATED: Countdown to Sputnik’s 50th Anniversary

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Space Shuttle Endeavour STS-118 Landing

Endeavour Lands! FULL STREAMING VIDEO

Endeavour kicks up dust as it touches down on runway 15 at NASA's Kennedy Space Center. The Space Shuttle Endeavour crew,

led by Commander Scott Kelly, completes a 13-day mission to the International Space Station. Photo credit: NASA, Kim Shiflett. View High Resolution Image, View Low Resolution Image

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Endeavour lands at Kennedy Space Center With commander Scott Kelly at the controls and six other astronauts on board, Space Shuttle Endeavour glided to a perfect landing at Kennedy Space Center in Florida to cap more than 12 days in space. STS-118 saw a new piece added to the International Space Station and 5,800 pounds of equipment and supplies transferred to the orbiting laboratory.

The landing also brought to an end teacher-turned-astronaut Barbara Morgan's first flight into space.

12:32 p.m. - Endeavour and its crew of seven astronauts landed safely on Kennedy Space Center's Runway 15, closing the book on the STS-118 mission to the International Space Station. Before the astronauts depart for the crew quarters, they'll take part in the traditional walkaround of the orbiter that has been their home for nearly two weeks. Once Endeavour is fully safed and ready to leave the runway, it will be towed to the nearby Orbiter Processing Facility, where it will begin processing for its next mission.

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Space Shuttle Endeavour STS-118 EVA

Constructing the Future

Joint Operations End; Endeavour Undocks High Resolution Image Full Size (2.30 Mb) During the third spacewalk astronauts Rick Mastracchio and Clay Anderson (out of frame) relocated the S-Band Antenna Sub-Assembly

from Port 6 (P6) to Port 1 (P1) truss, installed a new transponder on P1 and retrieved the P6 transponder. Image credit: NASA

The third spacewalk occurred Wednesday. It featured preparations for the relocation of the Port 6 truss from atop the station to the end of the Port 5 truss when STS-120 visits later this year. A fourth spacewalk took place Saturday in which an antenna was installed and two materials science experiments were retrieved for return to Earth.

In other activities, the two crews transferred cargo between Endeavour and the station.

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NASA Lunar Roving Vehicle (LRV)

The Lunar Roving Vehicle (LRV) gets a high-speed workout by astronaut John W. Young in the "Grand Prix" run during the third Apollo 16 extravehicular activity at the Descartes landing site.

This view is a frame from motion picture film exposed by a 16mm Maurer camera held by astronaut Charles M. Duke, Jr. While astronauts Young and Duke, lunar module pilot, descended onto the lunar surface to explore the Descartes highlands region of the moon, command module pilot Thomas K. Mattingly remained with the Command and Service Modules in lunar orbit. Image credit: NASA. High Resplution Image (1.15Mb)

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The Lunar Roving Vehicle (LRV) was an electric vehicle designed to operate in the low-gravity vacuum of the Moon and to be capable of traversing the lunar surface, allowing the Apollo astronauts to extend the range of their surface extravehicular activities. Three LRVs were driven on the Moon, one on Apollo 15 by astronauts David Scott and Jim Irwin, one on Apollo 16 by John Young and Charles Duke, and one on Apollo 17 by Gene Cernan and Harrison Schmitt.

Each rover was used on three traverses, one per day over the three day course of each mission. On Apollo 15 the LRV was driven a total of 27.8 km in 3 hours, 2 minutes of driving time. The longest single traverse was 12.5 km and the maximum range from the LM was 5.0 km. On Apollo 16 the vehicle traversed 26.7 km in 3 hours 26 minutes of driving. The longest traverse was 11.6 km and the LRV reached a distance of 4.5 km from the LM. On Apollo 17 the rover went 35.9 km in 4 hours 26 minutes total drive time. The longest traverse was 20.1 km and the greatest range from the LM was 7.6 km. The Apollo Lunar Roving Vehicle

Related:

• A Brief History of the Lunar Roving Vehicle (.pdf)
• Lunar Rover Operations Handbook

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Spintronic Devices

JILA research shows that electrons tend to hold consistent 'spins' longer in low-energy, disordered areas of a semiconductor (representing by the valleys of the cartoon), while spinning more erratically in higher-energy areas of a perfect crystal where movement is more fluid (represented by the mountains and air).

Use of NIST Information (THIS IMAGE): These World Wide Web pages are provided as a public service by the National Institute of Standards and Technology (NIST). With the exception of material marked as copyrighted, information presented on these pages is considered public information (PUBLIC DOMAIN) and may be distributed or copied. Use of appropriate byline, photo, image credits is requested. High Resolution Image

Type: Graphic/illustration. Source: National Institute of Standards and Technology. Credit Line as it should appear in print: Credit: J. Fal/JILA. AV Number: 07PHY007, Date Created: February 15, 2007, Date Entered: 2/15/2007

Disorder May Be in Order for ‘Spintronic’ Devices

Physicists at JILA are using ultrashort pulses of laser light to reveal precisely why some electrons, like ballet dancers, hold their spin positions better than others—work that may help improve spintronic devices, which exploit the magnetism or “spin” of electrons in addition to or instead of their charge. One thing spinning electrons like, it turns out, is some disorder.

JILA is a joint venture of the National Institute of Standards and Technology (NIST) and the University of Colorado at Boulder.

Electrons act like tiny bar magnets whose poles can point up or down. So-called “spintronic” circuits that sense changes in electron spin already are used in very high-density data storage devices, and other spin-based devices are under study. Greater exploitation of spintronics will require spins to be stable—in this case meaning that electrons can maintain their spin states for perhaps tens of nanoseconds while also traveling microscale distances through electronic circuits or between devices.

Scientists have suspected for some time that electrons best maintain the same spin direction at a “magic” electron density. New JILA measurements, described in Nature Physics,* suggest where the magic originates, revealing that electrons actually hold their spins for the longest time—three nanoseconds—when confined around defects, or disordered areas, in semiconductors. They lose their spin alignment in just a few hundred picoseconds when flowing through perfect areas of the crystal. This finding explains the role of density: at very low density, electrons are strongly confined to different local environments, whereas at extremely high density, electrons start hitting each other and lose spin control very fast. The magic point of maximum spin memory occurs at the cross-over between these two conditions.

The JILA research is the first to characterize the so-called electronic disorder in semiconductors and connect it to the spin dynamics. Disorder may arise because, when thin films are being made, imperfections consisting of even one extra layer of a few atoms create islands where electrons act as if they were trapped in stationary molecules. The new findings present a design challenge for spintronic devices, because the conditions that best preserve memory are not conducive to optimum transport properties.

The JILA team confined electrons in “quantum wells,” and used a visible laser beam of varying intensity to systematically vary electron density in the wells. For the measurements, infrared laser pulses were applied in pairs. The first pulse excites some electrons and gives them a spin, creating a temporary magnet. The polarization of light from the second pulse, reflected off the quantum wells, is rotated by the electrons. By measuring the magnitude of that rotation, the researchers infer how many electrons have the same spin. Then an external magnetic field is applied and the electrons rotate around the field, flipping their spins up and down as they go, and causing the reflected light’s polarization to oscillate. Based on the oscillation patterns, scientists can infer electron disorder and calculate spin retention times.

The research was supported in part by the National Science Foundation. The quantum wells were provided by the University of Manchester, United Kingdom.

* Z. Chen, S.G. Carter, R. Bratschitsch, P. Dawson and S.T. Cundiff. Effects of disorder on electron spin dynamics in a semiconductor quantum well. Nature Physics. Posted online Feb. 11, 2007. Disorder May Be in Order for ‘Spintronic’ Devices

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