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Stability of the embankment is largely concerned with the height and pavement type in permafrost area. Climate is another key factor. The heat transfer model with phase change and finite element method are used to simulate the thermal regime of permafrost beneath embankment of Qinghai-Tibet Highway, considering the changing of pavement type, height of embankment and climate warming since the building of the road was started in 1954. In-situ observation of ground temperature was performed. Simulated results indicate that increasing embankment height can decrease the depth of permafrost table temporarily, and then the permafrost table goes deeper soon. Heat absorbing of black pavement is a key factor that causes permafrost degradation beneath the embankment. Both the simulated and the measured results indicate a continuous trend of permafrost degradation beneath both the embankment and the natural ground under the scenario of climate warming, which implies that only increase the embankment height is not enough to keep it stable.

In 2008, the New York State Department of Taxation and Finance sent letters to clients of a fraudulent tax preparer, warning them of a possible audit and asking them to participate in the Department’s Voluntary Disclosure and Compliance Program if they had filed inaccurate tax returns in the past. This study examines the impact of the letters on voluntary compliance in their future (2008 and 2009) returns. In this study, a simple method similar to “difference in differences”, which we call “difference in positions”, is applied. 10,000 samples are randomly drawn from the taxpayer population and the growth rates of Federal adjusted gross income (AGI) for these samples are put into relative frequency density graphs. We then examine the relative positions of the experiment group (the clients of the fraudulent tax preparer) within the normally distributed curves before and after the letters were sent. The change in the relative positions is regarded as the letter impact on voluntary compliance. It is found that the impact is significant in the first year (2008 tax returns) after the letters were sent. The impact is 17.49 percentage points on the AGI growth rate, which translates to $8.68 million of reported AGI for the 507 taxpayers in the experiment group. However, the impact is minimal in the second year (2009 tax returns), indicating that the long-run effect of the letter mailings may be weak.

Based on the recognition that the evasion of real estate tax is much more difficult than the evasion of personal income tax and the assumption that, in general, taxpayers with similar income would consume a similar amount of housing and pay a similar amount of real estate tax, we build a model to estimate the personal income tax gap for business income earners in New York State. More specifically, we compare reported Federal adjusted gross income (AGI) between two groups of taxpayers: wage earners and business income earners. With the assumption that the wage income earners fully report their income, we find that there is a huge reporting gap of AGI for the business income earners in New York State as a whole. The income gap is $67.8 billion in 2007, which accounts for 26.2 percent of the total AGI the business income earners would have reported if they had been totally compliant with tax laws. If we apply the median of the New York State personal income tax rate, 5.25 percent, to the income gap, the personal income tax gap for the business income earners in the State in 2007 reaches $3.6 billion.