Some context: Fazlur Rahman Khan (Bengali: phjlur rhmaan khaan, Fozlur Rohman Khan) (3 April 1929 - 27 March 1982) was a Bangladeshi-American structural engineer and architect, who initiated important structural systems for skyscrapers. Considered the "father of tubular designs" for high-rises, Khan was also a pioneer in computer-aided design (CAD). He was the designer of the Sears Tower, since renamed Willis Tower, the tallest building in the world from 1973 until 1998, and the 100-story John Hancock Center. Khan, more than any other individual, ushered in a renaissance in skyscraper construction during the second half of the 20th century.
Khan's central innovation in skyscraper design and construction was the idea of the "tube" structural system for tall buildings, including the framed tube, trussed tube, and bundled tube variants. His "tube concept", using all the exterior wall perimeter structure of a building to simulate a thin-walled tube, revolutionized tall building design. Most buildings over 40 stories constructed since the 1960s now use a tube design derived from Khan's structural engineering principles. Lateral loads (horizontal forces) such as wind forces, seismic forces, etc., begin to dominate the structural system and take on increasing importance in the overall building system as the building height increases. Wind forces become very substantial, and forces caused by earthquakes, etc. are important as well. The tubular designs resist such forces for tall buildings. Tube structures are stiff and have significant advantages over other framing systems. They not only make the buildings structurally stronger and more efficient, but also significantly reduce the structural material requirements. The reduction of material makes the buildings economically more efficient and reduces environmental impact. The tubular designs enable buildings to reach even greater heights. Tubular systems allow greater interior space and further enable buildings to take on various shapes, offering added freedom to architects. These new designs opened an economic door for contractors, engineers, architects, and investors, providing vast amounts of real estate space on minimal plots of land. Khan was among a group of engineers who encouraged a rebirth in skyscraper construction after a hiatus of over thirty years. The tubular systems have yet to reach their limit when it comes to height. Another important feature of the tubular systems is that buildings can be constructed using steel or reinforced concrete, or a composite of the two, to reach greater heights. Khan pioneered the use of lightweight concrete for high-rise buildings, at a time when reinforced concrete was used for mostly low-rise construction of only a few stories in height. Most of Khan's designs were conceived considering pre-fabrication and repetition of components so projects could be quickly built with minimal errors. The population explosion, starting with the baby boom of the 1950s, created widespread concern about the amount of available living space, which Khan solved by building upward. More than any other 20th-century engineer, Fazlur Rahman Khan made it possible for people to live and work in "cities in the sky." Mark Sarkisian (Director of Structural and Seismic Engineering at Skidmore, Owings & Merrill) said, "Khan was a visionary who transformed skyscrapers into sky cities while staying firmly grounded in the fundamentals of engineering."
What else can you tell me about the tubular systems?
A: They not only make the buildings structurally stronger and more efficient, but also significantly reduce the structural material requirements.

Some context: Allen Welsh Dulles (; April 7, 1893 - January 29, 1969) was an American diplomat and lawyer who became the first civilian Director of Central Intelligence (DCI), and its longest-serving director to date. As head of the Central Intelligence Agency (CIA) during the early Cold War, he oversaw the 1954 Guatemalan coup d'etat, Operation Ajax (the overthrow of Iran's elected government), the Lockheed U-2 aircraft program and the Bay of Pigs Invasion. Following the assassination of John F. Kennedy, Dulles was one of the members of the Warren Commission. Between his stints of government service, Dulles was a corporate lawyer and partner at Sullivan & Cromwell.
After the outbreak of the Second World War, Dulles was recruited to work at the Office of Strategic Services and moved to Bern, Switzerland, where he lived at Herrengasse 23 for the duration of World War II. As Swiss Director of the OSS, Dulles worked on intelligence regarding German plans and activities, and established wide contacts with German emigres, resistance figures, and anti-Nazi intelligence officers. He was assisted in intelligence-gathering activities by Gero von Schulze-Gaevernitz, a German emigrant. Dulles also received valuable information from Fritz Kolbe, a German diplomat, one whom he described as the best spy of the war. Kolbe supplied secret documents regarding active German spies and plans regarding the Messerschmitt Me 262 jet fighter. Although Washington barred Dulles from making firm commitments to the plotters of the 20 July 1944 attempt to assassinate Hitler, the conspirators nonetheless gave him reports on developments in Germany, including sketchy but accurate warnings of plans for Hitler's V-1 and V-2 missiles. Dulles was involved in Operation Sunrise, secret negotiations in March 1945 to arrange a local surrender of German forces in northern Italy. After the war in Europe, Dulles served for six months as the OSS Berlin station chief and later as station chief in Bern. The Office of Strategic Services was dissolved in October 1945 and its functions transferred to the State and War Departments. In the 1948 Presidential election, Dulles was, together with his brother, an advisor to Republican nominee Thomas E. Dewey. The Dulles brothers and James Forrestal helped form the Office of Policy Coordination. During 1949 he co-authored the Dulles-Jackson-Correa Report, which was sharply critical of the Central Intelligence Agency, which had been established by the National Security Act of 1947. Partly as a result of the report, Truman named a new Director of Central Intelligence, Lieutenant General Walter Bedell Smith.
what happened with his posting to bern?
A:
After the outbreak of the Second World War, Dulles was recruited to work at the Office of Strategic Services and moved to Bern, Switzerland,