You might consider dropping the most problematic classes and take a lighter load of classes.
When the plots were classified according to the ≥75 % species proportion, the most problematic case was the 'mixed' class including plots of lower dominance of the various species.
However, their high chemical stability, persistence, pronounced lipophilicity, and tendency to bioaccumulate, as well as their extensive technical production and use from 1929 to the 1970s, still make PCBs one of the world's most widespread and problematic classes of environmental contaminants (Erickson 2001; Safe 1993).
The most problematic activities and animals encountered in laboratory classes include, in order of discomfort level, human dissection, human bodies, animal dissection, snakes, spiders, and lizards.
While these streamline student choices, they also come with a downside: they can introduce name confusions (e.g., in our class, nine students share the same first name) and are most problematic when students use nicknames.
The most problematic aspect, he added, was that speedy options were originally meant for innovative, first-in-class products, but are now being used mainly for drugs that are "less likely to be innovative".
The polymyxin class, known since 1947 and mostly represented by polymyxin B and polymyxin E (colistin), and tigecycline (the first representative of the new class of glycylcyclines) have recently been granted a major role in the treatment of the most problematic MDR Gram-negative pathogens (ESBL- and carbapenemase-producing strains) and enterobacteria.
Most problematic were prescription drugs.
Most problematic of all is iTunes.
