Few issues in American politics prompt more partisan passions and conflicting points of view than tax policy. One would think that there would be a definitive historical record of successes and failures that could inform future policy, but since other macro economic trends are operating at the same time, it can be difficult for economists to isolate the impact of tax cuts and hikes independent of these confounding factors.

Plastic trash is a potential — and plentiful — fuel source, but up to the present many regions of the United States have been reluctant to adopt waste-to-energy technologies. Among the reasons are the availability of relatively cheap land for trash disposal, recyclers who viewed such programs as potential threats, and resistance by local homeowners.

Governments in developed countries often provide foreign aid to developing countries in an effort to improve economic, social and political development. Regardless of the intended use for the money, recipient governments sometimes employ the funds to keep civil peace and to accommodate the demands of new groups, especially in times of tension. A sudden withdrawal of foreign aid could thus trigger internal struggles.

Political science scholarship has focused extensively on how voters make choices as the presidential primary campaign formally unfolds. But there has been relatively little study of which factors shape voter preferences in the informal period before the primaries.

In the past, studies of large-scale changes to the Earth’s oceans have been restricted both by the limited nature of physical sampling and the reality that often these changes occur over great lengths of time.

Hydropower accounts for two-thirds of all renewable electricity production in the United States. A 2008 paper by the University of Missouri at Saint Louis, “The Potential of Water Power in the Fight Against Global Warming,” discusses the potential for hydropower in reducing U.S. greenhouse gas emissions.

China and India are long-term rivals and nuclear powers who share a contested border. As their relative geopolitical strength increases and ability to project power expands, it is not clear how China and India will interact on the regional and global stages with one another in the years to come.