  The persistent character of the motion of active particles gives rise to
accumulation at boundaries. I investigate the problem of run-and-tumble
swimmers confined in a 1D box with hard walls, reporting expressions for the
particles probability distribution and wall pressure. A crossover box length
value is found below which the initial value of the pressure turns out to be
higher than the asymptotic one, indicating a bounce effect of the active "wave"
of swimmers. The case of attracting and repelling boundaries are also
investigated using two different tumble rates for particles in the bulk and at
walls. Escape problems are finally analyzed by considering partially permeable
walls through which particles can leave the box.

Statistical Mechanics;Soft Condensed Matter