// Preload nav elements
 
if (document.images) {
    
    var homedown = new Image();
    homedown.src = "/images/nav-home-white.png";
    var aboutdown = new Image();
    aboutdown.src = "/images/nav-about-white.png";
    var publicationsdown = new Image();
    publicationsdown.src = "/images/nav-publications-white.png";
    var reviewsdown = new Image();
    reviewsdown.src = "/images/nav-reviews-white.png";
    var newsdown = new Image();
    newsdown.src = "/images/nav-news-white.png";
    var audiodown = new Image();
    audiodown.src = "/images/nav-audio-white.png";
    var imagesdown = new Image();
    imagesdown.src = "/images/nav-images-white.png";
    var contactdown = new Image();
    contactdown.src = "/images/nav-contact-white.png";
 
    var homeup = new Image();
    homeup.src = "/images/nav-home-grey.png";
    var aboutup = new Image();
    aboutup.src = "/images/nav-about-grey.png";
    var publicationsup = new Image();
    publicationsup.src = "/images/nav-publications-grey.png";
    var reviewsup = new Image();
    reviewsup.src = "/images/nav-reviews-grey.png";
    var newsup = new Image();
    newsup.src = "/images/nav-news-grey.png";
    var audioup = new Image();
    audioup.src = "/images/nav-audio-grey.png";
    var imagesup = new Image();
    imagesup.src = "/images/nav-images-grey.png";
    var contactup = new Image();
    contactup.src = "/images/nav-contact-grey.png";
 
}
 

// Rollover functions

function deactivate(imageName) {
    if (document.images)
        document[imageName].src = eval(imageName + 'up.src');
}

function activate(imageName) {
    if (document.images)
        document[imageName].src = eval(imageName + 'down.src');
}