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Messages - tanvir28

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EEE / The glorious Mayan civilization (part2-early cities)
« on: March 05, 2015, 12:19:32 PM »
EARLY MAYA, 1800 B.C. TO A.D. 250
The earliest Maya settlements date to around 1800 B.C., or the beginning of what is called the Preclassic or Formative Period. The earliest Maya were agricultural, growing crops such as corn (maize), beans, squash and cassava (manioc). During the Middle Preclassic Period, which lasted until about 300 B.C., Maya farmers began to expand their presence both in the highland and lowland regions. The Middle Preclassic Period also saw the rise of the first major Mesoamerican civilization, the Olmecs. Like other Mesamerican peoples, such as the Zapotec, Totonac, Teotihuacán and Aztec, the Maya derived a number of religious and cultural traits–as well as their number system and their famous calendar–from the Olmec.
In addition to agriculture, the Preclassic Maya also displayed more advanced cultural traits like pyramid-building, city construction and the inscribing of stone monuments.
The Late Preclassic city of Mirador, in the northern Peten, was one of the greatest cities ever built in the pre-Columbian Americas. Its size dwarfed the Classic Maya capital of Tikal, and its existence proves that the Maya flourished centuries before the Classic Period.

EEE / The glorious Mayan civilization (part1-beginning)
« on: March 05, 2015, 12:17:44 PM »
The Maya Empire, centered in the tropical lowlands of what is now Guatemala, reached the peak of its power and influence around the sixth century A.D. The Maya excelled at agriculture, pottery, hieroglyph writing, calendar-making and mathematics, and left behind an astonishing amount of impressive architecture and symbolic artwork. Most of the great stone cities of the Maya were abandoned by A.D. 900, however, and since the 19th century scholars have debated what might have caused this dramatic decline.
The Maya civilization was one of the most dominant indigenous societies of Mesoamerica (a term used to describe Mexico and Central America before the 16th century Spanish conquest). Unlike other scattered indigenous populations of Mesoamerica, the Maya were centered in one geographical block covering all of the Yucatan Peninsula and modern-day Guatemala; Belize and parts of the Mexican states of Tabasco and Chiapas; and the western part of Honduras and El Salvador. This concentration showed that the Maya remained relatively secure from invasion by other Mesoamerican peoples.
Within that expanse, the Maya lived in three separate sub-areas with distinct environmental and cultural differences: the northern Maya lowlands on the Yucatan Peninsula; the southern lowlands in the Peten district of northern Guatemala and adjacent portions of Mexico, Belize and western Honduras; and the southern Maya highlands, in the mountainous region of southern Guatemala. Most famously, the Maya of the southern lowland region reached their peak during the Classic Period of Maya civilization (A.D. 250 to 900), and built the great stone cities and monuments that have fascinated explorers and scholars of the region.

Teaching & Research Forum / Re: PHD positions in cryptography
« on: March 05, 2015, 10:15:57 AM »

Teaching & Research Forum / Re: PHD in cryptography
« on: March 05, 2015, 10:15:32 AM »

Thanks for sharing the links.

Teaching & Research Forum / Re: GRE scores-Accepting universities
« on: March 05, 2015, 10:13:51 AM »

good post.


informative post.

Teaching & Research Forum / Re: Ten Tips for Asking Good Questions
« on: March 05, 2015, 10:08:46 AM »
good post.

EEE / The beginning of Internet : World wide web (p-5)
« on: March 05, 2015, 10:05:31 AM »
Cerf’s protocol transformed the Internet into a worldwide network. Throughout the 1980s, researchers and scientists used it to send files and data from one computer to another. However, in 1991 the Internet changed again. That year, a computer programmer in Switzerland named Tim Berners-Lee introduced the World Wide Web: an Internet that was not simply a way to send files from one place to another but was itself a “web” of information that anyone on the Internet could retrieve. Berners-Lee created the Internet that we know today.
Since then, the Internet has changed in many ways. In 1992, a group of students and researchers at the University of Illinois developed a sophisticated browser that they called Mosaic. (It later became Netscape.) Mosaic offered a user-friendly way to search the Web: It allowed users to see words and pictures on the same page for the first time and to navigate using scrollbars and clickable links. That same year, Congress decided that the Web could be used for commercial purposes. As a result, companies of all kinds hurried to set up websites of their own, and e-commerce entrepreneurs began to use the Internet to sell goods directly to customers. More recently, social networking sites like Facebook have become a popular way for people of all ages to stay connected.

EEE / The beginning of Internet : Rapid growth (p-4)
« on: March 05, 2015, 10:04:29 AM »
By the end of 1969, just four computers were connected to the ARPAnet, but the network grew steadily during the 1970s. In 1971, it added the University of Hawaii’s ALOHAnet, and two years later it added networks at London’s University College and the Royal Radar Establishment in Norway. As packet-switched computer networks multiplied, however, it became more difficult for them to integrate into a single worldwide “Internet.”
By the end of the 1970s, a computer scientist named Vinton Cerf had begun to solve this problem by developing a way for all of the computers on all of the world’s mini-networks to communicate with one another. He called his invention “Transmission Control Protocol,” or TCP. (Later, he added an additional protocol, known as “Internet Protocol.” The acronym we use to refer to these today is TCP/IP.) One writer describes Cerf’s protocol as “the ‘handshake’ that introduces distant and different computers to each other in a virtual space.”

EEE / The beginning of Internet : concept of Login(p-3 )
« on: March 05, 2015, 10:03:19 AM »
In 1965, another M.I.T. scientist developed a way of sending information from one computer to another that he called “packet switching.” Packet switching breaks data down into blocks, or packets, before sending it to its destination. That way, each packet can take its own route from place to place. Without packet switching, the government’s computer network—now known as the ARPAnet—would have been just as vulnerable to enemy attacks as the phone system.


In 1969, ARPAnet delivered its first message: a “node-to-node” communication from one computer to another. (The first computer was located in a research lab at UCLA and the second was at Stanford; each one was the size of a small house.) The message—“LOGIN”—was short and simple, but it crashed the fledgling ARPA network anyway: The Stanford computer only received the note’s first two letters.

EEE / The beginning of Internet : Birth of ARPANET(p-2)
« on: March 05, 2015, 10:01:16 AM »
After Sputnik’s launch, many Americans began to think more seriously about science and technology. Schools added courses on subjects like chemistry, physics and calculus. Corporations took government grants and invested them in scientific research and development. And the federal government itself formed new agencies, such as the National Aeronautics and Space Administration (NASA) and the Department of Defense’s Advanced Research Projects Agency (ARPA), to develop space-age technologies such as rockets, weapons and computers.


Scientists and military experts were especially concerned about what might happen in the event of a Soviet attack on the nation’s telephone system. Just one missile, they feared, could destroy the whole network of lines and wires that made efficient long-distance communication possible. In 1962, a scientist from M.I.T. and ARPA named J.C.R. Licklider proposed a solution to this problem: a “galactic network” of computers that could talk to one another. Such a network would enable government leaders to communicate even if the Soviets destroyed the telephone system.

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