The power of a powwow has been described as a collective heartbeat that draws people together. Celebrants often say they feel unity and freedom as they dance in a circle. Those elements are especially vital for those serving time at the Oregon State Correctional Institution in Salem, where life is spent behind barbed wire and fortified walls. But for one day a year, inmates get to don Native apparel and move to the rhythm of a rawhide drum with friends and loved ones.