function newImage(arg) {
  if (document.images) {
    rslt = new Image();
    rslt.src = arg;
    return rslt;
  }
}

function flip(name, type) {
  document[name].src = "/images/"+name+type+".png";
}

function flipPic(type) {
  document.portal.src = "/images/minis/"+type+".jpg";
}

var preloadFlag = false;
function preloadImages() {
  if (document.images) {
    home_over = newImage("/images/home-over.png");
    email_over = newImage("/images/email-over.png");
    map_over = newImage("/images/map-over.png");
    dental_hygienists_over = newImage("/images/dental_hygienists-over.png");
    dental_assistants_over = newImage("/images/dental_assistants-over.png");
    laboratory_staff_over = newImage("/images/laboratory_staff-over.png");
    business_office_over = newImage("/images/business_office-over.png");
    office_pictures_over = newImage("/images/office_pictures-over.png");
    procedures_over = newImage("/images/procedures-over.png");

    preloadFlag = true;
  }
}