Weihnachten customs held upon returning from church leading to the gift giving vary across the German-speaking countries. One of the most common situations sees the returning children wait to enter into their (locked) living room until a little bell rings. This bell marks the departure of the one delivering gifts. In the more Catholic regions - primarily South Germany and Switzerland - this is considered the Christ Child ("Christkind"), while those in North Germany commonly consider it to be the "Weihnachtsmann" (Saint Nicholas or Santa Claus) who is exiting. The children then enter to see the decorated Weihnachtsbaum (Christmas tree), with
Rina Tannenbaum Rina Tannenbaum Rina (Irena) Tannenbaum (born December 13, 1953) is an Israeli/American materials scientist and chemical engineer and presently Professor in the Program of Chemical and Molecular Engineering in the Department of Materials Science and Engineering at the State University of New York at Stony Brook. She received her Ph.D. in chemical engineering from the Swiss Federal Institute of Technology in Zurich. She has performed research in numerous areas including potential applications of carbon nanotubes, self-assembly, block copolymers, cellulose nanocomposites and tissue engineering. She has authored more than 150 publications in these fields that were published in top-tier journals, such