A volume study is an ultrasound that helps your healthcare provider plan your cancer treatment. Information from the ultrasound about the size and shape of your prostate is used to develop the cancer treatment plan.
For similar reasons, I find " light " (the opposite of " heavy ") and " spread out " (the opposite of " congested ", i.e. "smaller population per unit volume") unsatisfying. I would like a single, atomic word that enjoys some currency in scientific prose, which means precisely " less mass per unit volume ".
Single word for "less mass per unit volume" (the complement of "dense")
Traffic volume has been idiomatic for a very long time, going back to shipping in the 16th century. Volume made a bit more literal sense when talking about wine or timber, but has faithfully followed traffic as that term has expanded its scope over the centuries. I feel volume emphasizes the commodity nature of the data stream and the business of its transport, whereas amount serves better ...
What is the convention for use of "volume" or "amount" in reference to ...
Ah, but new experts will rise up and embrace the new, friendly Stack Overflow that they have always wanted. And maybe rediscover the same things the bitter, hateful old guard found.
You should use new when you wish an object to remain in existence until you delete it. If you do not use new then the object will be destroyed when it goes out of scope.