标题： 拉伸前缘不仅仅是被拉的 显示英文标题

标题： Pulled fronts are not (just) pulled

摘要： 前缘传播进入不稳定状态通常由线性化决定，即传播速度与不稳定状态下线性化方程的预测一致。 然后，前沿的行为是一个以线性扩展速度传播的高斯尾部。 跟随这一前沿的前沿通常被称为拉动前沿，暗示它们被这个前沿的高斯尾部“拉动”。 我们在这里描述了一类例子，说明这些一阶效应并不能完全描述前沿后方的动力学。 事实上，前沿行为最多只能预测两种可能的入侵情景，分别与高斯尾部的正负振幅相关，但我们的例子表现出三种或更多具有不同后方状态的入侵前沿。 因此，产生的入侵过程会留下一个不仅由前沿决定的状态，而不仅仅是被高斯尾部拉动的状态。 显示英文摘要

摘要： Front propagation into unstable states is often determined by the linearization, that is, propagation speeds agree with predictions from the linearized equation at the unstable state. The leading edge behavior is then a Gaussian tail propagating with the linear spreading speed. Fronts following this leading edge are commonly referred to as pulled fronts, alluding to the idea that they are ``pulled'' by this leading-edge Gaussian tail. We describe here a class of examples that exhibits how these leading-order effects do not completely describe the dynamics in the wake of the front. In fact, leading edge behavior predicts at most two possible invasion scenarios, associated with positive and negative amplitudes of the Gaussian tail, but our examples exhibit three or more invasion fronts with different states in the wake. The resulting invasion process therefore leaves behind a state that is not solely determined by the leading edge, and thus not just pulled by the Gaussian tail.