Under the local Langlands correspondence, the conductor of an irreducible representation of $\text{G}{{\text{l}}_{n}}\left( F \right)$ is greater than the Swan conductor of the corresponding Galois representation. In this paper, we establish the geometric analogue of this statement by showing that the conductor of a categorical representation of the loop group is greater than the irregularity of the corresponding meromorphic connection.

We compute the algebras of self-extensions of the vacuum module and the Verma modules over an affine Kac–Moody algebra $\hat{\mathfrak g}$ in suitable categories of Harish-Chandra modules. We show that at the critical level these algebras are isomorphic to the algebras of differential forms on various spaces of opers associated to the Langlands dual Lie algebra of ${\mathfrak g}$, whereas away from the critical level they become trivial. These results rely on and generalize the description of the corresponding algebras of endomorphisms obtained by Feigin and Frenkel and the description of the corresponding graded versions due to Fishel, Grojnowski and Teleman.

Cuttings of two clones of Norway spruce, Picea abies (L.) Karst., were exposed to three different ozone concentrations in open-top chambers during four months in the summer of 1990. The treatments were charcoal-filtered air, non-filtered air and non-filtered air with extra ozone (c. 30 ppb) added daily between 1100–1800 local time. During the last 4 wk of the exposure period, half the seedlings were drought-stressed, while the remainder were well watered. Biomass, gas exchange and water potential were measured during the drought stress period.

The ozone treatments affected the two clones very differently. High ozone reduced the rate of biomass increase in the faster-growing clone (clone M) whereas ozone generally stimulated the rate of biomass increase in the slower-growing clone (clone L). At the end of the measuring period, the high-ozone treatments reduced the rate of root biomass increase of the well watered seedlings of the M-clone, but it had no effect on the drought-stressed seedlings of the same clone, probably because the root growth was already to a large extent inhibited by the drought stress.

The treatment with the highest concentration of ozone partly protected the seedlings of the M clone against the drought stress, presumably by delaying shoot growth and thus delaying the increase in the total transpiring needle area. As a result, stomata tended to close less during the drought period in this treatment.

The results are discussed in relation to the suggested critical level for ozone effects on trees.