A topological space X is said to be star Lindelöf if for any open cover U of X there is a Lindelöf subspace A ⊂ X such that St(A, U) = X. The “extent” e(X) of X is the supremum of the cardinalities of closed discrete subsets of X. We prove that under V = L every star Lindelöf, first countable and normal space must have countable extent. We also obtain an example under MA + ¬CH, which shows that a star Lindelöf, first countable and normal space may not have countable extent.
The bicarbonate compensation concentration (BCC) measmed in Scenedesmus quadricauda increased significantly with increasing total alkalínity (TA): ířom 2-5 inmol(HC03') m'^ at an alkalinity of 0.5 mol m'^ to 416-444 mmol(HC03") m"^ at an alkalinity of 10 mol m'^. This should be taken into account when evaluating a species ability to use HC03’. The increase of BCC at higher alkalinities could be caused by carbonate inhibition of HC03‘ uptake and/or by extremely high assimilatory pH reached.