The phrase "active professor" is correct and usable in written English.
It can be used to describe a professor who is currently engaged in teaching, research, or other academic activities.
Example: "Dr. Smith is an active professor in the Department of Biology, regularly publishing research and mentoring students."
Alternatives: "engaged professor" or "current professor".
At about age 50, productivity stabilizes for the rest of their career (for active professors) or decreases slowly (for all professors).
Figure 1 presents the distribution of the number of professors by age (A), as well as the percentage of active professors (B).
As one would expect, the percentage of active professors increases steadily between 28 and 40, remains at its highest level between 40 and 55, and decreases slowly thereafter (Figure 1B). Figure 2 shows the growth of the average annual number of papers per professor, with at least one paper over the period 2000 2007, using "active" professors and "all" professors as denominators.
Our data nonetheless show clearly that active professors' productivity reaches its maximum during their fifties and tends to remain at that level until retirement.
Comparing the curves for all professors with those for the active subset shows that the latter does not drop significantly after 50, and that active professors sustain their productivity at a high level throughout their careers.
It shows the average number of papers per researcher in the top 10% of journals ordered by decreasing impact factor and the top 10% most cited papers, using first all professors (A,B) and then only active professors (C,D).
Part of the explanation for the fact that average impact decreases between 28 and 50 and increases afterwards while productivity is rather stable for active professors can be found in Figure 5.
The average productivity of "all professors" counts, in its denominator, all professors that are in our sample, irrespective of whether they have published at a given age, while the average productivity of "active professors" only includes in its denominator those who published at least one paper at the age in question.
However, when only the set of active researchers is considered as the denominator (C,D), the average number of papers in the top 10% highest impact continues to rise steadily until at least 70, the oldest age for which we have at least 100 active professors in our database.
It shows that the production of reviews by active professors increases steadily from 28 years old until 50, and gradually decreases afterwards, suggesting that there may be an optimal age to write such reviews reflecting the state of the art in a field.
