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Precision measurements of the quantum Hall resistance with alternating current (ac) in the kHz range were performed on epitaxial graphene in order to assess its suitability as a quantum standard of impedance. The quantum Hall plateaus measured with alternating current were found to be flat within one part in 107. This is much better than for plain GaAs quantum Hall devices and shows that the magnetic-flux-dependent capacitive ac losses of the graphene device are less critical. The observed frequency dependence of about --8 x 10--8/kHz is comparable in absolute value to the positive frequency dependence of plain GaAs devices, but the negative sign is attributed to stray capacitances which we believe can be minimized by a careful design of the graphene device. Further improvements thus may lead to a simpler and more user-friendly quantum standard for both resistance and impedance. [ABSTRACT FROM AUTHOR]

Biobehavioral research, especially that which is conducted with prisoners, has become much more closely regulated in the last 30 years. State and federal law, as well as professional standards, regulate the conduct of many types of research; in the case of prisoners, this regulation is even more stringent. However, currently no mandatory, uniform, national regulatory or oversight process exists, and many privately funded research endeavors are operating in a regulatory void. In response to this, the National Bioethics Advisory Commission has argued for the creation of a single, national, independent regulatory body to oversee all human participant research, regardless of funding source. As ethicolegal research standards evolve alongside advances in science and technology, an appreciation of the history of prisoner research and an awareness of current standards is critical to conducting ethical prison research. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]