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
Emmanuel David Tannenbaum subsequently devoted his research to studying various problems in evolutionary dynamics using quasispecies models. His seminal work centered on the key question of the evolutionary advantages of sexual reproduction. Tannenbaum demonstrated a strong selective advantage for sexual reproduction with fewer and much less restrictive assumptions than previously considered. Closely related to this line of reasoning, was the original work by Tannenbaum and James Sherley on the immortal strand hypothesis. Tannenbaum also proposed a pioneering theory of why higher organisms need sleep. Towards the end of his life, he proposed a new approach to anti-stealth technology based on the theory of