Full electrical control of Charge and Spin conductance through Interferometry of Edge States in Topological Insulators

We investigate electron interferometry of edge states in Topological Insulators. We show that, when inter-boundary coupling is induced at two quantum point contacts of a four terminal setup, both Fabry-P\'erot-like and Aharonov-Bohm-like loop processes arise. These underlying interference effects lead to a full electrically controllable system, where the magnitude of charge and spin linear conductances can be tuned by gate voltages, without applying magnetic fields. In particular we find that, under appropriate conditions, inter-boundary coupling can lead to negative values of the conductance. Furthermore, the setup also allows to selectively generate pure charge or pure spin currents, by choosing the voltage bias configuration.Comment: 12 pages, 5 figures (expanded discussion section, corrected typos

U.S.-CANADA BORDER DISPUTES IN GRAINS: DYNAMIC INTERFACE BETWEEN THE FREE TRADE AGREEMENT AND TRADE REMEDY LAWS

Agricultural trade between the United States and Canada has been contentious since the inception of the CUSTA agreement in 1989. Even though Canadian exports of wheat and barley are not found to have violated U.S. trade remedy laws, friction seems likely to continue as long as the surge in Canadian exports remains unabated. Gradual harmonization of trade policies, farm subsidy programs, and marketing institutions may reduce trade disputes between the two countries in the future. To diffuse the threat of future trade disputes, a Canada - U.S. joint research team should be formed to deal with the matter through better understanding for causes of the disputes.bilateral trade, free trade agreement, trade disputes, trade remedy laws, farm income, farm price, harmonization, International Relations/Trade,

United States and Canadian Free Trade Agreement: Economic Implications

International Relations/Trade,

THE MITOGENIC ACTIVITY OF POLYADENYLICPOLYURIDYLIC ACID COMPLEXES

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72586/1/j.1749-6632.1975.tb29085.x.pd

Effect of quasi-bound states on coherent electron transport in twisted nanowires

Quantum transmission spectra of a twisted electron waveguide expose the coupling between traveling and quasi-bound states. Through a direct numerical solution of the open-boundary Schr\"odinger equation we single out the effects of the twist and show how the presence of a localized state leads to a Breit-Wigner or a Fano resonance in the transmission. We also find that the energy of quasi-bound states is increased by the twist, in spite of the constant section area along the waveguide. While the mixing of different transmission channels is expected to reduce the conductance, the shift of localized levels into the traveling-states energy range can reduce their detrimental effects on coherent transport.Comment: 8 pages, 9 color figures, submitte

Operation characteristics of piezoelectric quartz tuning forks in high magnetic fields at liquid helium temperatures

Piezoelectric quartz tuning forks are investigated in view of their use as force sensors in dynamic mode scanning probe microscopy at temperatures down to 1.5 K and in magnetic fields up to 8 T. The mechanical properties of the forks are extracted from the frequency dependent admittance and simultaneous interferometric measurements. The performance of the forks in a cryogenic environment is investigated. Force-distance studies performed with these sensors at low temperatures are presented