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Dear Professor Silberstein,
I'm fairly new to the air conditioning trade and I had heard through the grapevine that you were going to have a seminar on Pressure - Enthalpy. The tech that I worked with all summer said I really should consider going to your seminar because I really need to know this stuff if I want to do well in the trade. I basically have only two questions; 1.What is it? and 2.Why do I need it? Oh, and where and when is it if I decide to go?