jQuery Mobile and KO.js - one way binding

HTML

<html>
<head>
<link rel="stylesheet" href="http://code.jquery.com/mobile/1.3.2/jquery.mobile-1.3.2.min.css" />
<script src="http://code.jquery.com/jquery-1.9.1.min.js"></script>

<script src="http://code.jquery.com/mobile/1.3.2/jquery.mobile-1.3.2.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/knockout/2.3.0/knockout-min.js"></script>



</head>
<body>
jQuery Mobile data-* attribute<br/>

    <fieldset data-role="controlgroup" data-type="horizontal">
    <label><input type="radio" value="Yes" name='Vote' data-bind="checked: Vote" />Yes</label>
    <label><input type="radio" value="No" name='Vote' data-bind="checked: Vote" />No</label>
    <label><input type="radio" value="Abstain" name='Vote' data-bind="checked: Vote" />Abstain</label>
</fieldset>
    
<span data-bind="text: Vote"></span>



<script type="text/javascript">

viewModel = {
    Vote: ko.observable('Yes')
};

ko.applyBindings(viewModel);



</script>
</body>
</html>