Though it now recycles or otherwise reuses 80 percent of waste from its operations in the United States, it's the remaining 20 percent that poses difficult problems, Ms. Lockwood said.
The poorly trained and only moderately organized militias are often suspicious of one another and are sometimes openly hostile, posing difficult problems for the transitional council now trying to govern the country.
As predictive tools for water resources, water quality, natural hazard mitigation and water availability assessment are generally data-driven, the lack of adequate hydrometric records poses difficult problems for planners, engineers, managers, and stake-holders alike.
The proliferation of stent designs poses difficult problems to clinicians, who have to learn the relative merits of all stents to ensure optimal selection for each lesion, and also to regulatory authorities who have the dilemma of preventing the inappropriate marketing of substandard stents while not denying patients the benefits of advanced technology.
Coastal ecosystems are likely to be the first to pose difficult conservation problems, as sea level rise inundates protected areas or makes them more vulnerable to damage in storms.
As elsewhere in the world, these giant agglomerations pose difficult social and aesthetic problems, but, by concentrating population, they help to prevent some areas of the countryside from becoming too built-up.
In computer vision, occlusions are almost always seen as undesirable singularities that pose difficult challenges to image motion analysis problems, such as optic flow computation, motion segmentation, disparity estimation, or egomotion estimation.
The hotter stars pose more difficult problems, since Earth's atmosphere extinguishes all radiation at wavelengths shorter than 2900 Å.
Gödel's incompleteness theorems pose very difficult problems for Carnap in this and other regards.
