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.
Lambskin condoms are good for preventing pregnancy. Because the lambskin material has tiny pores--though they are not large enough to allow the passage of sperm--it is not considered to prevent the passage of certain STDs, particularly viruses like HIV and herpes. They should not be used as protection against diseases.