Current produced by thermocouples. My understanding is that the thermocouple voltage is strictly a function of the temperature. Apparently this is called the Seebeck Voltage. Like any voltage source there is an internal resistance associated with it due to real world effects.
HIV/AIDS. Condoms for HIV prevention. Condoms, when used correctly and consistently, are highly effective in preventing HIV and other sexually transmitted infections (STIs). A large body of scientific evidence shows that male latex condoms have an 80% or greater protective effect against the sexual transmission of HIV and other STIs.
It was once thought that using condoms with nonoxynol-9 helped to prevent STDs by killing the organisms that can cause disease. New research shows that doing so also irritates a woman's vagina and cervix and may increase the risk of an STD infection. Current recommendations are to avoid using condoms with nonoxynol-9.