Aula_ Aztecs

Aztec Math Used Hearts and Arrows How big is a heart? Two and a half land rods of course, according to the Aztecs By David Biello - April 3, 2008 for The Scientific American

AZTEC MATH: The Aztec used symbols such as arrows and hearts to denote fractional units of measurement in surveying records like the Oztoticpac Lands Map pictured here. COURTESY OF LIBRARY OF CONGRESS The Aztecs had more numbers than we do, or at least symbols denoting numerical concepts. When it came to measuring land— critical for levying the proper tax or tribute— these medieval Mesoamericans used arrows, hearts, hands and other units representing fractions, according to a new study in Science. To figure this out, mathematician Maria del Carmen Jorge y Jorge of the National Autonomous University of Mexico (U.N.A.M) channeled the mind of an Aztec land surveyor. That meant retraining herself to use a different numerical system and combing through the Codex Vergara, one of two remaining books that record Aztec land surveying. Working with geographer Barbara Williams and del Carmen Jorge y Jorge counted 367 fields in this book with both an overall area for the plot of land as well as the lengths of the sides. Roughly 60 percent of these fields had areas that matched the basic mathematical rule of length multiplied by width or other common surveying calculations. But the rest were off, usually by a small amount. And 69 had areas that were prime numbers such as 211— numbers that cannot be created by multiplying two whole numbers together, such as 20 times 10. Instead, del Carmen Jorge y Jorge determined that the Aztecs were using the equivalent of fractions. "We found these smaller units of measure that we call monads that have the role of a fraction," she says. "We don't like to call them fractions, though, because they were considered as unitary entities like inches, seconds or minutes." To denote half the Aztec basic unit of measure—known by Aztec experts as tlalquahuitl or land rods—the surveyors used an arrow symbol. So for a field that measured 20 land rods by 10 land rods plus an arrow (or 20 multiplied by 10.5), the correct area was 210. "Two arrows is one unit, five hearts is two units, five hands is three units," del Carmen Jorge y Jorge notes. These extra units—arrow, heart, hand, bone and arm—cannot be subdivided further, standing alone as essentially extra numbers. It is unclear what exactly these measurements equal, but the team speculates that an arrow is the measure of the length from the shoulder to the hand (like an archer with a taut bow), a heart is a measure of the length from that organ to the tip of the hand and a hand as the measure from outstretched hand to outstretched hand—just as an English foot is the measure of a man's foot. "That could be an interpretation," del Carmen Jorge y Jorge says. "We cannot prove it." The researchers will next try to assess the accuracy of the Aztec surveyors. The neighborhood of Asuncion outside Mexico City still bears the markings of the ancient Aztec terraced fields on its hillsides that were recorded in the Codex Vergara. "We were there trying to measure those terraces," del Carmen Jorge y Jorge says. "This is complicated because this is sloping land." It is no doubt easier to measure sloping land with modern devices like satellite global positioning systems and computers than it is to try to inhabit an alternative mathematical system and devise the meaning of mysterious symbols—as well as grasp the algorithms that can explain how they were used. "I can use my math, my computers and whatever I want," she says. "With this paper, I am only using hand calculations."

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DOES TURNING FLUORESCENT LIGHTS OFF USE MORE ENERGY THAN LEAVING THEM ON? INCANDESCENT LIGHTBULBS ARE LUMBERING TOWARD EXTINCTION. NOW, HOW BEST TO USE THEIR ENERGY-EFFICIENT REPLACEMENTS? By John Matson - March 27, 2008 – for the Scientific American

BETTER BULB: The compact fluorescent lightbulb is more energy efficient than its incandescent precursor, but is it better to leave it on? So you bought a compact fluorescent lightbulb in a bid to be green. Such bulbs are vastly more energyefficient than traditional incandescents and screw into standard sockets. Should you treat them like their older cousins? After all, four- and eight-foot- (1.2- and 2.4-meter-) long tubular bulbs common in more institutional settings are sometimes left on permanently, perhaps due to their slow, flickering start-ups. The thinking is that the boost of energy such bulbs require to power up means that it might be best to keep them on when leaving a room, rather than subjecting them to the stress of a restart on your return. Turns out, however, that power surge is so brief that its energy draw doesn't amount to much: the equivalent of a few seconds or so of normal operation, according to U.S. Department of Energy estimates. In other words, from a strict energy-conservation standpoint, it's almost always beneficial to shut off fluorescents when leaving the room—the start-up energy is offset by the power saved in even the briefest outages. But what about the wear and tear on the bulb itself? Being too switch-happy reduces the operating life of the lamp, and given that newer fluorescents are still a few times more expensive than old-fashioned incandescents, it makes sense to forestall burnouts. There are also real environmental impacts of their production and disposal to consider. A simple rule of thumb that balances both concerns is to shut off fluorescents if you’re planning to leave a room for more than five minutes, according to Francis Rubinstein, a staff scientist in the Building Technologies Department at Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division. Mary Beth Gotti, manager of the GE Lighting & Electrical Institute in Cleveland, agrees. For all practical purposes, "it almost always makes sense to turn the lights off," Gotti says. "From an environmental standpoint, the best way to save energy is to turn off the things that you're not using." Rubinstein notes that, even for fluorescents, the cost of electricity over a bulb's lifetime far outpaces the cost of the bulb itself. "Even if you switch on and off a fluorescent light frequently," he says, "the slight reduction in lamp life is a small effect relative to the energy savings you accomplish by being a good citizen." Gotti adds that the reduction in lamp life from frequent on-and-off switching can often be counterbalanced by the extension of "calendar life"—the actual passage of time between lightbulb replacements—that results from using the bulb for fewer hours. That sort of calculation will probably become more common as compact fluorescent lightbulbs come down in price, cast more pleasant light and, most importantly, force their power-hungry competitors from store shelves. The Australian government will phase out the sale of traditional incandescents in that country by 2010, and the U.S. Congress has effectively mandated the same ban domestically by 2012. But whereas that new fluorescent bulb is sure to lower utility bills in your home, the real energy-crunch savior has been there all along: the light switch.

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RESEARCHERS: CLOAK OF INVISIBILITY TECHNICALLY POSSIBLE FOXNEWS - May 26, 2006

WASHINGTON — The key to creating a Harry Potter-like invisibility cloak lies in manmade materials unlike any in nature or the Hogwarts School of Witchcraft and Wizardry, researchers say. They're laying out a blueprint for turning science fiction into reality. And they say that, in theory, nothing's stopping them from making such a cloak. Well, almost nothing: They still need to perfect the manufacture of those exotic materials with an ability to steer light and other forms of electromagnetic radiation around a cloaked object, rendering it as invisible as something tucked into a hole in space. "Is it science fiction? Well, it's theory and that already is not science fiction. It's theoretically possible to do all these Harry Potter things, but what's standing in the way is our engineering capabilities," said John Pendry, a physicist at Imperial College London. Details of the study, which Pendry co-wrote, appear in Thursday's online edition of the journal Science. Scientists not involved in the work said it presents a solid case for making invisibility an attainable goal. "This is very interesting science and a very interesting idea and it is supported on a great mathematical and physical basis," said Nader Engheta, a professor of electrical and systems engineering at the University of Pennsylvania. Engheta has done his own work on invisibility using novel materials called metamaterials. Pendry and his co-authors also propose using metamaterials because they can be tuned to bend electromagnetic radiation — radio waves and visible light, for example — in any direction. A cloak made of those materials, with a structure designed down to the submicroscopic scale, would neither reflect light nor cast a shadow. Instead, like a river streaming around a smooth boulder, light and all other forms of electromagnetic radiation would strike the cloak and simply flow around it, continuing on as if it never bumped up against an obstacle. That would give an onlooker the apparent ability to peer right through the cloak, with everything tucked inside concealed from view. "Yes, you could actually make someone invisible as long as someone wears a cloak made of this material," said Patanjali Parimi, a Northeastern University physicist and design engineer at Chelton Microwave Corp. in Bolton, Mass. Parimi was not involved in the research. Such a cloak does not exist, but early versions that could mask microwaves and other forms of electromagnetic radiation could be as close as 18 months away, Pendry said. He said the study was "an invitation to come and play with these new ideas." "We will have a cloak after not too long," he said. The Pentagon's Defense Advanced Research Projects Agency supported the research, given the obvious military applications of such stealthy technology. While Harry Potter could wear his cloak to skulk around Hogwarts, a real-world version probably would not be something just to be thrown on, Pendry said. "To be realistic, it's going to be fairly thick. Cloak is a misnomer. 'Shield' might be more appropriate," he said.

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WATCHDOG AGENCY: TREATY TO ELIMINATE CHEMICAL WEAPONS “IS SUCCEEDING”

THE HAGUE, 8 APRIL 2008 - OPCW NEWS/ PRESS RELEASES SOURCE: OFFICIAL SITE OF THE ORGANIZATION FOR PROHIBITION OF CHEMICAL WEAPONS – WWW.OPCW.NL The agency responsible for implementing the international Chemical Weapons Convention has reported that steady progress is being made to eliminate global stockpiles of chemical weapons and the means to produce them, but warned that a dozen countries must still join the treaty -- including five in the Middle East1 -- before universal compliance can be assured. The report was issued today by the Organisation for the Prohibition of Chemical Weapons (OPCW) on the eve of a major review conference that begins in The Hague on Monday, 7 April 2008. “The Chemical Weapons Convention is the only international treaty that aims to eliminate an entire category of weapons of mass destruction, and it is succeeding,” said the OPCW Director-General, Ambassador Rogelio Pfirter. “At a time when the credibility of the multilateral system in this area has been questioned we have demonstrated that global disarmament under strict international verification is possible. However, the Convention is only as strong as its weakest link, and securing universal adherence remains our most important and difficult challenge.” Director-General Pfirter added that several of the remaining 12 countries that have not ratified the Convention may join in the near future, including at least one from the Middle East. The Convention was signed at an international ceremony in Paris in January 1993 and took effect four years later. Among the main achievements cited by the OPCW report: • 183 countries have now ratified the Convention representing about 98% of the world’s population and chemical industry, making OPCW the fastest growing UN disarmament treaty organisation in history. • Of the 65 chemical weapons productions facilities declared under the Convention by 12 States Parties2, 100% have been de-activated and 61 of them either completely destroyed or converted to peaceful uses. • Of the more than 70,000 metric tonnes of chemical agents declared by six States Parties3, more than 37% have been verifiably destroyed with remaining stocks scheduled for destruction by 2012. • Of the 8.6 million chemical munitions and containers covered by the Convention, 100% have been inventoried and verified, and one third destroyed. • More than 3,000 inspections have taken place since 1997 at more than 1,000 chemical weapons-related and industrial sites on the territory of 80 States Parties to verify compliance with the Convention. The completion of chemical weapons disarmament within the Convention’s timelines is at the core of the current phase of implementation. On 11 July 2007, Albania became the first of six States Parties to completely destroy its declared chemical weapons stockpile. The other five have all complied in a timely fashion with their intermediate destruction deadlines. The Russian Federation has destroyed nearly a quarter of its declared stockpiles and expressed confidence it will achieve destruction of 45% by 2009. For its part, the United States of America has already destroyed half of its declared stockpile and is ahead of its second intermediate deadline. Another State Party is expected to complete destruction of its stockpiles in 2008, India by April 2009, and the Libyan Arab Jamahiriya by 2011. Chemical weapons were a scourge of 20th century warfare, beginning in World War I when they killed over 90,000 soldiers and injured 1 million. Under Saddam Hussein, Iraq deployed chemical weapons on a massive scale against Iranian forces and Iraqi Kurds during the 1980s, killing and maiming tens of thousands. In 19941995 the Aum Shinrikyo doomsday cult staged terrorist attacks with sarin nerve agent in Japan that killed 19 and injured more than 6,000 others. notes 1. There are five Signatory States that have yet to ratify the Convention (Bahamas, Dominican Republic, Guinea-Bissau, Israel, Myanmar), and seven non-Signatory States (Angola, Democratic People’s Republic of Korea, Egypt, Iraq, Lebanon, Somalia, Syrian Arab Republic). 2. The 12 States Parties that have declared chemical weapons production facilities are Bosnia and Herzegovina, China, France, India, the Islamic Republic of Iran, Japan, Libyan Arab Jamahiriya, Russian Federation, Serbia, United Kingdom, United States, and another State Party. 3. The six States Parties that have declared chemical weapons stocks are Albania, India, Libyan Arab Jamahirya, the Russian Federation, United States, and another State Party.

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