Infrastructure means the basic structure of an organization or system. A company's infrastructure would include all the fixed assets, i.e., the building, equipment, machinery and tools required to manufacture their product. Although people are not fixed assets they would be included in the company's infrastructure too.
Rarely a serious problem. Look-alikes: Jumping oak gall, tubakia leaf spot, oak leaf blister, other fungal leaf spots. Jumping oak gall Brown leaves appear on trees in the white oak group in late spring. Severe infections may cause the leaves to turn black, curl up and fall. On the underside are brown galls with the larva of a small wasp inside.
Keep in mind that it might be perfectly natural for lower leaves on your plant to first turn pale yellow, then brown and then drop off. This happens on many kinds of tropical plants as they grow. Over time, the plant will form a bare stem. However, in some cases, brown leaves are a sign of cultural problems.