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We report here a study of nitrogen and $\alpha$-capture element (O, S, andSi) abundances in 18 Damped Ly$\alpha$ Absorbers (DLAs) and sub-DLAs drawn fromthe ESO-UVES Advanced Data Products (EUADP) database. We report 9 newmeasurements, 5 upper and 4 lower limits of nitrogen that when compiled withavailable nitrogen measurements from the literature makes a sample of 108systems. The extended sample presented here confirms the [N/$\alpha$] bimodalbehaviour suggested in previous studies. Three-quarter of the systems show$\langle$[N/$\alpha$]$\rangle=-0.85$ ($\pm$0.20 dex) and one-quarter ratios areclustered at $\langle$[N/$\alpha$]$\rangle= -1.41$ ($\pm$0.14 dex). The high[N/$\alpha$] plateau is consistent with the HII regions of dwarf irregular andblue compact dwarf galaxies although extended to lower metallicities and couldbe interpreted as the result of a primary nitrogen production by intermediatemass stars. The low [N/$\alpha$] values are the lowest ever observed in anyastrophysical site. In spite of this fact, even lower values could be measuredwith the present instrumentation, but we do not find them below [N/$\alpha$]$\approx$ $-1.7$. This suggests the presence of a floor in [N/$\alpha$]abundances, which along with the lockstep increase of N and Si may indicate aprimary nitrogen production from fast rotating, massive stars in relativelyyoung or unevolved systems.

The ESO UVES Advanced Data Products Quasar Sample - III. Evidence of Bimodality in the [N/alpha] Distribution