function slider_next() {
  $(".slider-item").stop();
  i = 1;
  while ($('#slider-item-'+i).css("display") != "block") {
    ++i;
  }
  $('#slider-item-'+i).stop(true, true);
  $('#slider-item-'+i).hide("slide", {direction: "right"}, 250, function() {
    ++i;
    if($('#slider-item-'+i).size()) {
      $('#slider-item-'+i).show("slide", {direction: "left"}, 250);
    }
    else {
      $('#slider-item-1').show("slide", {direction: "left"}, 250);
    }
  
  });
  
}
function slider_previous() {
  i = 1;
  while ($('#slider-item-'+i).css("display") != "block") {
    ++i;
  }
  j = 1;
  while ($('#slider-item-'+j).size()) {
    ++j;
    maximum = j;
  }
  --j;
  $('#slider-item-'+i).stop(true, true);
  $('#slider-item-'+i).hide("slide", {direction: "left"}, 250, function() {
  --i;
  if($('#slider-item-'+i).size()) {
    $('#slider-item-'+i).show("slide", {direction: "right"}, 250);
  }
  else {
    $('#slider-item-'+j).show("slide", {direction: "right"}, 250);
  }
  
  });
}