You can see "establishing tense" used a lot at the beginning of newspaper stories, where an opening statement in the present perfect tense often indicates the range of time that the story will cover ("Election costs have risen 300% since 2000"), while an opening statement in the simple past tense often suggests a very short time-frame ("Stocks rose 2.1% on light trading [implicitly are sternly (and to my mind ludicrously) literal-minded about such temporal references, but to the best of my knowledge everybody else in academe accepts the ancient convention that a text which still 'speaks' to a present-day audience does so in the present tense.
In this example, the verb "twisted" is the only verb that appears in the past tense.
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Visit Stack Exchange Stone theorems have a long history. C and D [CD14] not only prove a stone theorem for the cake process in random environment, but also have a nice overview of existing results.
The cut-off point for "recent"—that is, the present—is "present conversation".
The present perfect is a convenient way to suggest that the matter is still "open" and that your paper is going to make a contribution to it.In the book's chapter, "Seeing," Annie Dillard contends that "vision...is a deliberate gift, the revelation of a dancer who for my eyes only flings away her seven veils" (17).There is no need to write about science in unusual, complicated, or overly formal ways in an effort to "sound scientific" or to impress your audience.If you can tell a friend about your work, you are off to a good start.However, there is a way that you can usefully shift tense in a literature review in a scientific paper.You can use the present tense for recent research that is still a topic of current conversation—especially if your paper extends or contradicts that research.In the present paper, we prove that stones in non-random cakes are indigestible.Switching to the various forms of the present tense suggests that the research in those tenses is more directly relevant to the "present" paper—that is, yours.When you are writing a paper, try to get your ideas across in such a way that the audience will understand them effortlessly, unambiguously, and rapidly.To this end, strive to write in a straightforward way.