A research of branch of a field of  knowledge?   A case study?

  Or if you are beggining, simply a subject (a topic).  Limits, derivatives, and integrals are
subjects of the Calculus in Discipline Maths.

  Let´s say, you have a field of knowledge (Chemical) and you are going to choose

a branch of it (Biochemical).

  Or let´s have another example, you study Biology (the broadly subject) and you are

researching marine biology (you consider going to this branch next).

  And there are the subfields, let´s read a wikipedia excerpt.
"The marine ecosystem is large, and thus there are many subfields of marine biology.
Most involve studying specializations of particular animal groups. (i.e. phycology,
 invertebrate zoology and ichthyology).

  Related fields
Marine biology is a branch of oceanography and is closely linked to biology.
 It also encompasses many ideas from ecology. Fisheries science and marine conservation  can be considered partial offshoots of marine biology.

Offshoots - desdobramento.
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  Ah, you could say that you are researching a specialization of Computing, say, productivity research in high performance computing, like the site on the bottom.

  Or a subject within the the study of computing, e.g. Microprocessor study, the wide subject being Computer Engineering.   Hope it somewhat helps, at least we got that

closer.

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CTWatch Quarterly » Software Productivity Research In High ... - [ Traduzir esta página ]Squires, S., Van De Vanter, M. L., Votta, L. G. "Software Productivity Research In High Performance Computing ," CTWatch Quarterly, Volume 2, Number 4A, ...
www.ctwatch.org/.../software-productivity-research-in-high-performance-computing/ -