The sievert (symbol: Sv) is the International System of Units (SI) derived unit of equivalent radiation dose, effective dose, and committed dose. Quantities that are measured in sieverts are designed to represent the stochastic biological effects of ionizing radiation. The sievert should not be used to express the unmodified absorbed dose of radiation energy, which is a clear physical quantity measured in grays. To enable consideration of biological effects, further calculations must be performed to convert absorbed dose into effective dose, the details of which depend on the biological context. This can be far more complicated than just multiplying by a weighting factor.

The sievert is of fundamental importance in radiation dosimetry, and is named after Rolf Maximilian Sievert, a Swedish medical physicist renowned for work on radiation dosage measurement and research into the biological effects of radiation. One sievert equals 100 rem, an older unit of measurement still in widespread use. One sievert carries with it a 5.5% chance of eventually developing cancer. Doses greater than 1 sievert received over a short time period are likely to cause radiation poisoning, possibly leading to death within weeks.

Jukka Tolonen (born April 16, 1952, Helsinki) is a Finnish jazz guitarist. Tolonen became famous as guitarist for the band Tasavallan Presidentti. While making several solo albums and projects he also played on albums Tombstone Valentine (1970) and Fairyport (1971) by Wigwam.

Tolonen is a virtuoso guitarist who is highly respected in his native Finland as well as in Sweden where he has lived for long periods. Among Tolonen's side projects are Guitarras Del Norte, Trio Tolonen, and Jukka Tolonen Band (JTB). He has used many different guitars over the years, such as the Gibson ES-335 and Ibanez Artist. Since the 90's he has used Finnish handmade instruments by Ruokangas Guitars (electric) and Lottonen Guitars (acoustic).

Tolonen contributed to Six Complete (2006), the latest album by Tasavallan Presidentti.

In May 2008 Tolonen was found guilty of stabbing his girlfriend and was sentenced to 27 months in jail for aggravated assault. When released in 2010 he told the media that he was quitting guitar playing due to osteoarthritis. While in prison Jukka Tolonen dedicated his life to Jesus Christ, and in 2011 he released "Juudan Leijona" ("Lion of Judah"), a CD of traditional Finnish hymns in which he sings and plays piano, occasionally accompanied by other instruments and voices.