ensp;</span>increases <span  title="" class="an ">&ensp;</span>about <span  title="" class="an ">&ensp;</span>twofold <span  title="" class="an ">&ensp;</span>without <span  title="" class="an ">&ensp;</span>accompanying <span  title="" class="an ">&ensp;</span>changes <span  title="" class="an ">&ensp;</span>in <span  title="" class="an ">&ensp;</span>the <span  title="" class="an ">&ensp;</span>mean <span  title="" class="an ">&ensp;</span>and <span  title="" class="an ">&ensp;</span>variance <span  title