Academic discourse; Scientific communication ; Academic language; Scientific language ; Vortrag; Recitation; Lecture ; Rhetoric, contrastive; Rhetorik, kontrastive; Contrastive rhetoric ; English as international medium ; Second language acquisition (pragm.) ; Zweitspracherwerb (pragm.) ; Interactionist hypothesis (second language acquisition) ; Conversational analysis (second language acquisition) ; English (American) ; USA (English language in the) ; USA (engl. Sprache in den) ; English in the USA; Englisch in den USA; American English