Peak uranium gold, silver, copper or nickel, uranium is not widely traded on an organized commodity exchange such as the London Metal Exchange. It is traded on the NYMEX but on very low volume. Instead, it is traded in most cases through contracts negotiated directly between a buyer and a seller. The structure of uranium supply contracts varies widely. The prices are either fixed or base on referenced to economic indices such as GDP, inflation or currency exchange. Contracts traditionally are based on the uranium spot price and rules by which the price can escalate. Delivery quantities, schedules, and prices vary from
Laplacian of the indicator from research on path integrals in quantum physics. This section shows how derivatives of the indicator can be treated numerically under an integral sign. In principle, the indicator cannot be differentiated numerically, since its derivative is either zero or infinite. But, for practical purposes, the indicator can be approximated by a bump function, indicated by "I"("x") and approaching the indicator for ε → 0. Several options are possible, but it is convenient to let the bump function be non-negative and approach the indicator "from below", i.e. 0 \leq I_\varepsilon(x)& \leq \mathbf{1}_ Laplacian of the indicator In mathematics, the Laplacian of