function SetNumRows(num_rows) {
  url = document.location + '';
  url = url.replace(/&page=(\d+)/,'');
  url = url.replace(/\?page=(\d+)/,'?page=0');
  url = url.replace(/&num_rows=(\d+)/,'');
  url = url.replace(/\?num_rows=(\d+)/,'');
  if (url.indexOf('?')==-1) url += '?';
  else url += '&';
  url += 'num_rows=' + num_rows;
  document.location = url;
}