Polymers comprising a polyethylenimine, a biodegradable group, and a relatively hydrophobic group are useful for the delivery of bioactive agents to cells. The light scanning unit includes a composite light source in which a plurality of light sources for emitting coherent light having different wavelengths are arranged adjacent to one another and an optical axis of each light source is arranged substantially parallel to each other and which emits light at a divergence angle centering on each optical axis. The pilot data are equalized based on the channel properties for determination of at least one pilot power and at least one interference power based on the equalized pilot data, and a rank indication is determined based on the at least one pilot power and the at least one interference power. Methods of administering such nutritional compositions to patients in need of same are also provided. A data access system and a computer-readable storage medium are also described and claimed. Using multiple data packet signal testers with narrower receiver bandwidths to process respective portions of the wider bandwidth of the data packet signals produced by the devices under test enables use of lower cost, narrower-bandwidth test equipment to test wide-bandwidth signals.