function startcalculator(lang) {
	if(!lang)	
		lang = "de";
  var calculator = window.open(
  	"http://www.systemecology.eu/SPEAR/calculator/index.php?lang="+ lang, 
  	"Calculator", 
  	"width="+ (screen.availWidth - 100) +","+
  	"height="+ (screen.availHeight - 150) +","+
  	"left=50,"+
  	"top=50,"+
  	"location=no,"+
  	"menubar=no,"+
  	"status=no,"+
  	"toolbar=no,"+	  	
  	"dependent=no,"+
  	"resizable=yes"	  	
  );
  
  calculator.focus();
}