Mathematics and the right member

Ozarfreo wrote this:
"Las condiciones naturales para plantearlo parecen ser las siguientes a primera vista: si "f" es una función real que depende de dos variables (x.t) , necesitamos que sea Riemann integrable en "x" para cualquier "t" fijo para que el miembro de la izquierda tenga sentido, y también que la derivada con respecto a "t" exista para todo "x" fijo para dar sentido al miembro derecho."
... It should be something like this in English:
"At first sight, the natural conditions to state the problem would be: if "f" is a real function that depends on two vars (x,t), we need it to be Riemann integrable (?) on "x" for any fixed "t", so that the member of the left is meaningful, and also that the derivative with "t" exists for any fixed "x" so that the right member has some sense..."
I particularly would like the right member to have some sense, and I agree that the natural conditions seems to be (clearly) the ones you mention. But I really don't want the right member to loose track, really. Could you give me his email?
Anyway, I love your page, ozarfreo. I will keep on reading when I'm not so sleepy. For a physicist (and I used to be one of them), it should be clear that the derivative of the integral of f is the integral of the derivative of f. But now that I'm not a physicist anymore, I think we could have an interesting conversation on that topic, and many others that have been rambling around my mind for the last couple of months... Congrats for your Physics Review paper. Shit, it's really amazing. You're good! Very good, indeed.
Ah, finally: I also miss you, man! Did you get my email?