This is the 491st most frequent Lithuanian word.
srityje
"In the field" or "in the area."
In this sentence, 'srityje' is the locative form of the noun 'sritis', meaning 'field' or 'area'. It specifies the professional area of IT where he works.
Jis dirba IT srityje.
He works in the IT field.
Here, 'srityje' again is in the locative case, denoting the specific area or field of science related to the discoveries.
Mokslininkai daro daug atradimų šioje srityje.
Scientists make many discoveries in this field.
'Srityje', in this instance, locatively marks 'visuomenės sveikatos', indicating a field of study or expertise.