Different communications protocols use different conventions for distinguishing between the elements of a packet and for formatting the user data. For example, in Point-to-Point Protocol, the packet is formatted in 8-bit bytes, and special characters are used to delimit the different elements. Other protocols, like Ethernet, establish the start of the header and data elements by their location relative to the start of the packet. Some protocols format the information at a bit level instead of a byte level.
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15th-century Mamluks depicted in The Arrest of St. Mark from the Synagogue, Giovanni di Niccolò Mansueti, 1499. Islamic individuals and costumes often provided the contextual backdrop to describe an evangelical scene. This was particularly visible in a set of Venetian paintings in which contemporary Syrian, Palestinian, Egyptian and especially Mamluk personages are employed anachronistically in paintings describing Biblical situations. An example in point is the 15th century The Arrest of St. Mark from the Synagogue by Giovanni di Niccolò Mansueti which accurately describes contemporary (15th century) Alexandrian Mamluks arresting Saint Mark in an historic scene of the 1st century CE. Another case is Gentile Bellini's Saint Mark Preaching in Alexandria.
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Polarization techniques have long been used in radio transmission to reduce interference between channels, particularly at VHF frequencies and beyond. Under some circumstances, the data rate of a radio link can be doubled by transmitting two separate channels of radio waves on the same frequency, using orthogonal polarization. For example, in point to point terrestrial microwave links, the transmitting antenna can have two feed antennas; a vertical feed antenna which transmits microwaves with their electric field vertical (vertical polarization), and a horizontal feed antenna which transmits microwaves on the same frequency with their electric field horizontal (horizontal polarization). These two separate channels can be received by vertical and horizontal feed antennas at the receiving station.
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He has stated many times that he is not interested in becoming a full-time MI6 agent. Alex's athletic talents greatly assist him during his missions many times: for example, in Point Blanc he snowboards down a mountain on an ironing board to escape Point Blanc Academy, in Skeleton Key he scuba dives into Skeleton Key, in Scorpia he base jumps into a factory, in Ark Angel he walks between two apartment buildings on a tightrope and in Snakehead, he kayaks down a river on a makeshift kayak. As the series progresses, Alex becomes more skilled at spying. He later pursues Damian Cray alone after MI6 refuse to investigate him, and is recruited by the CIA in the United States, and later by the ASIS in Australia although in each case only for specific missions.
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The boundaries between far infrared, terahertz radiation, microwaves, and ultra-high-frequency radio waves are fairly arbitrary and are used variously between different fields of study. Microwaves travel by line-of-sight; unlike lower frequency radio waves they do not diffract around hills, follow the earth's surface as ground waves, or reflect from the ionosphere, so terrestrial microwave communication links are limited by the visual horizon to about . At the high end of the band they are absorbed by gases in the atmosphere, limiting practical communication distances to around a kilometer. Microwaves are widely used in modern technology, for example in point-to-point communication links, wireless networks, microwave radio relay networks, radar, satellite and spacecraft communication, medical diathermy and cancer treatment, remote sensing, radio astronomy, particle accelerators, spectroscopy, industrial heating, collision avoidance systems, garage door openers and keyless entry systems, and for cooking food in microwave ovens.
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