con‧cen‧trate1 /ˈkɒnsəntreɪt $ ˈkɑːn-/ ●●● S2 W2 AWL verb
1 [intransitive] to think very carefully about something that you are doing → concentration
Now please concentrate.
Adrian was finding it difficult to concentrate.
concentrate on
Be quiet – let me concentrate on my homework.

2 [intransitive, transitive] to be present in large numbers or amounts somewhere, or to cause people or things to be present in large numbers or amounts somewhere → concentration

be concentrated in/at something
Italian industry is concentrated mainly in the north.
Construction of the aircraft is being concentrated at Prestwick.

concentrate in/at
Women concentrate in a small number of occupations.