Postal traffic to the US dropped more than 80% after the Trump administration ended the de minimis tariff exemption for low-cost imports, the United Nations postal agency said Saturday. The AP ...

6.3. The Tangent Line and the Normal to a Plane Curve 142 6.4. Cases of Non-differentiability of a Continuous Function 145 6.5. The Derivatives of Logarithmic and Exponential Functions 147 6.6. The ...

The daily Sea Ice Index provides a quick look at Arctic-wide changes in sea ice. It provides consistently processed daily ice extent and concentration images and data since 1979. Daily extent images ...