ScienceDaily (Jan. 10, 2011) — Ibn al-Haytham's 11th-century Book of Optics, which was published exactly 1000 years ago, is often cited alongside Newton's Principia as one of the most influential books in physics. Yet very little is known about the writer, considered by many to be the father of modern optics. January's Physics World features a fanciful re-imagining of the 10-year period in the life of the medieval Muslim polymath, written by Los Angeles-based science writer Jennifer Ouellette. The feature covers the time when al-Haytham -- banished from society and deprived of books -- came up with his revolutionary theories about the form and passage of light. Ouellette brings detail to the skeletal plot of al-Haytham's life, from the awe and intimidation felt when he was summoned by the Caliph to use his engineering prowess to overcome the annual flooding of the Nile, to his fear of punishment when he realised he had failed in his task. Al-Haytham was only able to escape a death sentence from the notoriously brutal Caliph by pretending he had gone mad. The Caliph instead incarcerated Al-Haytham, imprisoning him under house arrest to a cell. Confined and alone, it was here that Al-Haytham carried out the work that was to make him famous. In 11th-century Egypt, Aristotle's ancient thought that visible objects and our own eyes emit rays of light to enable our vision still held. Ouellette imagines al-Haytham lying alone in his darkened room questioning why the objects in the room are not emitting light and asking 'Is it possible that the ancients were mistaken?' The question providing the crux, al-Haytham was spurred into experimental action with the candles and copper in his bare room to conclude that there is no mysterious "form" that all objects emit; rather there are sources of primary light that are reflected by other objects. As Ouellette writes, "This is a work of fiction -- a fanciful re-imagining of a 10-year period in the life of Ibn al-Haytham, considered by many historians to be the father of modern optics. Living at the height of the golden age of Arabic science, al-Haytham developed an early version of the scientific method 200 years before scholars in Western Europe." Released from prison after the Caliph's death, Al-Haytham (AD 965-1040) went on to make contributions to astronomy, mathematics, engineering and medicine, as well as physics. But it his seven-volume Book of Optics, which he wrote while imprisoned, that remain his most famous contributions to science, covering visual perception, psychology and physical optics.
Creato da: diegobaratono il 02/05/2008
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Messaggi di Gennaio 2011
Post n°677 pubblicato il 31 Gennaio 2011 da diegobaratono
Da:"LiriciGreci.org" Egypt protest intensifies, Mubarak turns to army Factboxes
CAIRO | CAIRO (Reuters) - Protesters intensified their campaign on Monday to force Egypt's President Hosni Mubarak to quit as world leaders struggled to find a solution to a crisis that has torn up the Middle East political map. Crowds flocked in the morning to Tahrir Square, which has become the focus of the uprising over poverty, corruption and unemployment, to join protesters who had camped out overnight in defiance of a curfew imposed by Mubarak. Soldiers checked IDs but the crowd steadily grew, chanting "Down, down, Mubarak." The uprising against Mubarak's 30-year-rule, now in its sixth day, unnerved global markets. Share prices fell across Asia on Monday morning, Brent oil hit a 28-month high, and Egypt's financial markets were closed for a second day in a row. The mood between the troops and the protesters in the square remained generally relaxed, with people sharing food and standing by tanks daubed with anti-Mubarak graffiti. The army appears to hold the key to Mubarak's fate but although the generals have held back from crushing the revolt, they have also not withdrawn support for Mubarak. "The army has to choose between Egypt and Mubarak," read one banner in Tahrir Square. The protests in the world's most populous Arab nation broke out last week when frustration over repression and the lack of democracy under Mubarak's rule boiled over. More than 100 people were killed in clashes with security forces in scenes that overturned Egypt's standing as a stable country, promising emerging market and attractive tourist destination. Mubarak, a close U.S. ally and a stalwart in Western policy toward the Middle East, responded by offering economic reform to address public anger at rising prices. He also sacked his cabinet and appointed a vice president and new prime minister. Both, however, were military men and the moves have done nothing to appease a protest movement who want him and his associates from the old guard to be swept away. WEST WAIT-AND-SEE The United States, which has poured billions of dollars of aid into Egypt since Mubarak came to power, stopped short of saying openly that it wanted him out. President Barack Obama and Secretary of State Hillary Clinton instead urged reform and spoke about "an orderly transition." A senior U.S. official, who declined to be identified, said the feeling among Obama's national security aides was that Mubarak's time had passed, but it was up to Egyptians to determine what happens next. Washington has long seen Mubarak as a bulwark in the Middle East, first against communism then against militant Islam.
Post n°676 pubblicato il 28 Gennaio 2011 da diegobaratono
Da:"Antikitera.Net" Sabbagh H. http://www.english.globalarabnetwork.com/ RITROVATE 650 TAVOLETTE IN SCRITTURA CUNEIFORME Scoperte archeologiche nel sito di Tell Lilan situato a 120 km a nordest di Hasaka indicano l'importanza storica del sito, che risale agli inizi del secondo millennio aC. Il sito si trova su una delle importanti vie commerciali che collegavano le antiche Cappadocia, Ashur con i principali centri dell'Anatolia. Gli scavi che sono stati effettuati in vari settori nel sito dal 1978 mostrano che l'area è stata abitata per la prima volta durante la metà del sesto millennio aC ed ha continuato ad esserlo fino alla fine del 1800 aC. Sono state scoperte ceramiche risalenti al periodo Halaf (6500-5500 aC) e al periodo di Ubaid (6500-3800 aC), oltre a vasi a forma di campana, risalente al periodo di Uruk (4000-3100 aC). Gli scavi hanno scoperto un importante insediamento umano risalente al periodo di Ninive. Ceramiche dentata, tazze giallo, piedistalli di statue colorate e pentole . Il sito che misura quasi 15 ettari di terreno inizia ad essere abitato verso la prima metà del 3 ° millennio aC. Successivamente vi è stato ad un boom improvviso, sia in termini di popolazione che di sviluppo civile durante la metà del 2 ° millennio aC. Durante questo periodo, un muro e un sistema difensivo sono stati eretti per proteggere le aree residenziali in espansione, trasformando il sito da un piccolo villaggio ad una città che copre oltre 90 ettari. Un tempio è stato scoperto nel lato nord-est del sito. Le sue più spiccate caratteristiche sono le facciate, i pilastri decorati con motivi spiralati, ed un corridoio centrale, circondato da camere sui lati est e ovest.Sono stati trovati nel tempio anche ceramiche, sigilli, tavolette cuneiformi e cilindrici . Vi è un locale che si trova nella zona bassa del sito in cui è stato rinvenuto un archivio di 650 tavolette cuneiformi con scritti in dialetto antico babilonese, con i testi sia amministrativi che economici, messaggi politici e di trattati che fanno luce sugli sviluppi nel settore a seguito della caduta del città di Mari (circa 1759 aC). Secondo i testi trovati a Tel Lilan e altri siti, alla città fu dato il nome Shubat Enlil che significa "la casa di Enlil" (Enlil era un antico dio) dal re assiro Shamshi-Adad I. Prima di allora, era conosciuto come Shekhna, e questo nome è stato utilizzato nuovamente dopo la morte di Shamshi-Adad I nel 1776 aC. La città fu distrutta dal re Samsu-iluna di Babilonia nel 1728, e da allora è rimasta disabitata.
Post n°675 pubblicato il 28 Gennaio 2011 da diegobaratono
Dr. Zahi Hawass
Salima Ikram Professor of Egyptology
Water and Way stations: Monday, February 7, 2011 6:00 PM Reception to Follow
Ahmad Pasha Kamal Hall
Post n°674 pubblicato il 27 Gennaio 2011 da diegobaratono
Post n°673 pubblicato il 27 Gennaio 2011 da diegobaratono
Da:"ScienceMagazine" How Giants Conquered the Earth ![]() Missing link? A reconstruction of the "near-sauropod" dinosaur Leonerasaurus taquetrensis. Credit: Diego Pol How did animals the size of a goat evolve into the largest creatures on Earth? The discovery of a new dinosaur from Argentina, announced today, may offer some clues. Paleontologists have known for decades about the beginnings and endings of a group of dinosaurs known as the Sauropodomorpha. At first, around 230 million years ago, most of these creatures were omnivorous and small, about the size of a tricycle. But over the course of 80 million years, they evolved into tractor-trailer sized, long-necked plant-eaters—like Apatosaurus, formerly known as Brontosaurus. These were the giants called sauropods. Scientists also knew about a related group called prosauropods, dinosaurs that were intermediate in size and posture. What they didn't know was exactly what steps filled in the transition between prosauropods and sauropods. Until recently, the remains of intermediates closely related to the sauropods were extremely rare and fragmentary. That has now changed with the discovery of Leonerasaurus taquetrensis, the closest relative yet to the giant sauropods. Paleontologist Diego Pol of the Egidio Feruglio Paleontological Museum in Trelew, Argentina, and colleagues took three summers to painstakingly excavate the fossilized bones from steep outcrops at a remote spot in southern Argentina. The specimen, reported about online today in PLoS ONE, isn't complete, but it shares many features of both sauropods and prosauropods. For example, the 8-foot-long Leonerasaurus is tiny compared with sauropods, which ranged from 30 to perhaps 130 feet in length, but it had already evolved an important feature needed for gigantism: a beefed up sacrum, the fused vertebrae of the lower spine. Scientists had assumed that great mass would have produced selective pressure for the larger sacrum, but now they know that the sacral enlargement came first. New teeth were also critical to Leonerasaurus. An animal aspiring to greatness would not politely chew its food, but would snip and swallow quickly. The fossil record catches Leonerasaurus at a moment when its teeth had only partly made the switch. Leonerasaurus had traded in its old front teeth for the advanced, spoon-shaped models—while retaining primitive, leaf-shaped back teeth. Pol had observed the same pattern in his earlier study of Mussaurus, a "near-sauropod" known only from juvenile skeletons. Apparently front teeth changed first, back teeth later. Paleontologist Adam Yates of the University of the Witwatersrand, Johannesburg, in South Africa, who was not involved in the study, says Leonerasaurus shows us that many of the distinctive characteristics of sauropods evolved long before the dinosaurs became gigantic. Last year, he noticed something similar in a South African prosauropod called Aardonyx. Its limb proportions seemed fortuitously adapted for a slower lifestyle—and its interlocking forearm bones for changing body balance—both in a way that would later prove invaluable for an extreme weight gain. "The thing about sauropods is that they have a unique combination of evolutionary novelties," says Martin Sander of the University of Bonn in Germany. "This combination led to an evolutionary cascade, one thing leading to another, that allowed them to get so big." Still, "the progression was not smooth and simple," says Yates. "It was a messy affair with separate lineages evolving similar traits, reversing others, and generally muddying up our understanding of the shape of the sauropodomorph family tree."
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