Düsseldorf's Lord Mayor Dr Stephan Keller (CDU) has been in office for about nine months. On a joint racing bike tour, VIVID editor Rainer Kunst spoke with him about a very special start in office, future transport and economic policy, the importance of table tennis for Düsseldorf's health and the need for a 700-million-euro opera house.

Since 2003 he has topped the world rankings four times, at the European Championships he won seven titles in singles and five in doubles, at the World Championships he came third in singles and was runner-up in doubles: Timo Boll is the most successful German table tennis player of all time so far - and a star in China, the country of the table tennis world champions. The 40-year-old is not only popular for his fair play in sport, but also for his great social commitment to people in need. He has been under contract with the top German League team Borussia Düsseldorf since 2006.

Every year, about 200,000 people in Germany develop Alzheimer's disease, a condition that is as of yet incurable. Scientists from all over the world are searching for the causes in order to decipher the disease and develop effective drugs. One of them is Annette Limke. She has a doctorate in biology and is investigating the effects of ultra-fine particulate on the risk of Alzheimer's disease. An interview with the 32-year-old about exhaust fumes, the goal of her research project and her love of nature.