The minimum energy, and, more generally, the
minimum cost, to transmit one bit of information has been recently derived for
bursty communication when information is available infrequently at random times
at the transmitter. This result assumes that the receiver is always in the
listening mode and samples all channel outputs until it makes a decision. If
the
receiver is constrained to sample only a fraction r 
of the channel outputs, what is the cost penalty due to sparse output
sampling?

Remarkably, there is no penalty: regardless of $r > 0$ the asynchronous capacity
per unit cost is the same as under full sampling, i.e., when $r = 1$. 
Moreover, there is no penalty in terms of decoding delay. The latter result
relies on the possibility
to sample adaptively.