Christmas in Sweden is still symbolised by a barrel of ale, or a drinking horn. So the emphasis on food and drink traditions was originally a pagan trait of the Christmas celebration. The Christmas tree is a custom that was imported from Germany in the 1880s. The foremer tradition of giving joke presents, often a log of wood, was replaced during the late-19th century and 20th century by Christmas gifts given out by the Christmas goat ("Julbocken") or, especially later, Santa Claus ("Jultomten"). The Christmas celebrations in Sweden usually starts with the first Advent in the end of November. However Christmas decorations and
Allen Tannenbaum thesis advisor Heisuke Hironaka at the Harvard University in 1976. Tannenbaum has done research in numerous areas including robust control, computer vision, and biomedical imaging, having almost 500 publications. He pioneered the field of robust control with the solution of the gain margin and phase margin problems using techniques from Nevanlinna–Pick interpolation theory, which was the first H-infinity type control problem solved. Tannenbaum used techniques from elliptic curves to show that the reachability does not imply pole assignability for systems defined over polynomial rings in two or more variables over an arbitrary field. He pioneered the use of partial differential