And if we can get something that's measurably less expensive than hydrocarbons, completely clean, and providing the same reliability, which is a very key constraint for energy systems, that I will consider a miracle. (scientificamerican.com)
Although the teacher has obtained snacks for his students to increase their productivity in the afternoons which will likely have some impact on their classroom performance, he has not yet secured guided reading materials which are far more likely to «address key constraints of increased class performance.» (teachingasleadership.org)
«When making robots the size of insects, simplicity and low power are always key constraints.» (seas.harvard.edu)