A computing system including a script module to perform a run-time extension to modify the functionality of a corresponding World Wide Web application object is described. The subject compositions are characterized by having a positively charged porous matrix and a urea derivative dye on at least one surface of the matrix, where in many preferred embodiments the urea derivative dye is a negatively charged urea derivative dye. If the event rates are not correlated, other parameterized data from the mechanical signal and electrical signal are evaluated to detect evidence of an arrhythmia.