Explosion of an upward-biased walk with geometrically increasing rates
= Explosion of an upward-biased walk with geometrically increasing rates
Suppose a transient nearest-neighbour jump chain on $\mathbb N$ has uniformly bounded expected visits to each state and the holding rate at $i$ grows geometrically. Then
$$
\mathbb E\sum_n\frac1{q_{Y_n}}
=\sum_i\frac{\mathbb E V_i}{q_i}<\infty,
$$
so the continuous-time chain explodes almost surely.