an>are <span  title="" class="an ">&ensp;</span>attributable <span  title="" class="an ">&ensp;</span>to <span  title="" class="an ">&ensp;</span>the <span  title="" class="an ">&ensp;</span>N <span  title="" class="an ">&ensp;</span>P <span  title="" class="an ">&ensp;</span>Q <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>R <span  title="" class="an ">&ensp;</span>type <span  title="" class="an ">&ensp;</span>channels <span  title="" class="an ">&ensp;</span>especial