THE INFLUENCE OF TECHNOLOGICAL PROGRESS ON THE LONG RUN FARM LEVEL ECONOMICS OF SOIL CONSERVATION

The complementary interaction between topsoil depth and technical progress for winter wheat in the Palouse region was found to strengthen the long run payoff to conservation tillage. Nonetheless, conservation tillage was found to be competitive with conventional tillage only if its current yield disadvantages were eliminated. Conservation tillage was relatively more competitive on shallower topsoils and for longer planning horizons. Short-term subsidies coupled with research directed towards reducing the cost and yield disadvantages of conservation tillage in the Palouse were advocated to maintain long-term soil productivity.Land Economics/Use, Research and Development/Tech Change/Emerging Technologies,

Time Variable Faraday Rotation Measures of 3C-273 and 3C-279

Multifrequency polarimetry with the VLBA confirms the previously reported time-varying Faraday rotation measure (RM) in the quasar 3C-279. Variability in the RM and electric vector position angle (EVPA) of the jet component (C4) is seen making it an unreliable absolute EVPA calibrator. 3C-273 is also shown to vary its RM structure on 1.5 year time-scales. Variation in the RM properties of quasars may result from a Faraday screen which changes on time-scales of a few years, or from the motion of jet components which sample spatial variations in the screen. A new component emerging from the core of 3C-279 appears to be starting to sample such a spatial variation. Future monitoring of this component and its RM properties is suggested as a diagnostic of the narrow line region in 3C-279. We also present a new method of EVPA calibration using the VLA Monitoring Program.Comment: Accepted to ApJ Letters. 12 pages, 5 figure

Transport Equations and Spin-Charge Propagating Mode in the Two Dimensional Hole Gas

We find that the spin-charge motion in a strongly confined two-dimensional hole gas (2DHG) supports a propagating mode of cubic dispersion apart from the diffusive mode due to momentum scattering. Propagating modes seem to be a generic property of systems with spin-orbit coupling. Through a rigorous Keldysh approach, we obtain the transport equations for the 2DHG, we analyze the behavior of the hole spin relaxation time, the diffusion coefficients, and the spin-charge coupled motion

Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells

We show that the Quantum Spin Hall Effect, a state of matter with topological properties distinct from conventional insulators, can be realized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of the quantum well, the electronic state changes from a normal to an "inverted" type at a critical thickness $d_c$. We show that this transition is a topological quantum phase transition between a conventional insulating phase and a phase exhibiting the QSH effect with a single pair of helical edge states. We also discuss the methods for experimental detection of the QSH effect.Comment: 22 pages. Submitted to Science for publication on Aug 14, 200

Quantized Electric Multipole Insulators

In this article we extend the celebrated Berry-phase formulation of electric polarization in crystals to higher electric multipole moments. We determine the necessary conditions under which, and minimal models in which, the quadrupole and octupole moments are topologically quantized electromagnetic observables. Such systems exhibit gapped boundaries that are themselves lower-dimensional topological phases. Furthermore, they manifest topologically protected corner states carrying fractional charge, i.e., fractionalization at the boundary of the boundary. To characterize these new insulating phases of matter, we introduce a new paradigm whereby `nested' Wilson loops give rise to a large number of new topological invariants that have been previously overlooked. We propose three realistic experimental implementations of this new topological behavior that can be immediately tested.Comment: Main text: 9 pages, 6 figures. Supplementary Material: 37 pages, 15 figures. Submitted on Jul 25, 201

The Extreme Compact Starburst in MRK 273

Images of neutral Hydrogen 21cm absorption and radio continuum emission at 1.4 GHz from Mrk 273 were made using the Very Long Baseline Array and Very Large Array. These images reveal a gas disk associated with the northern nuclear region with a diameter of 0.5'' (370 pc), at an inclination angle of 53deg. The radio continuum emission is composed of a diffuse component plus a number of compact sources. This morphology resembles those of nearby, lower luminosity starburst galaxies. These images provide strong support for the hypothesis that the luminosity of the northern source is dominated by an extreme compact starburst. The HI 21cm absorption shows an east-west gradient in velocity of 450 km/s across 0.3'' (220 pc), implying an enclosed mass of 2e9 M_solar, comparable to the molecular gas mass. The brightest of the compact sources may indicate radio emission from an active nucleus (AGN), but this source contributes only 3.8% to the total flux density of the northern nuclear region. The HI 21cm absorption toward the southeast radio nucleus suggests infall at 200 km/s on scales < 40 pc, and the southwest near IR nucleus is not detected in high resolution radio continuum images.Comment: standard AAS format, 23 pages, 5 figures, fixed figure. To appear in ApJ Letter