On transport in quantum Hall systems with constrictions

Motivated by recent experimental findings, we study transport in a simple phenomenological model of a quantum Hall edge system with a gate-voltage controlled constriction lowering the local filling factor. The current backscattered from the constriction is seen to arise from the matching of the properties of the edge-current excitations in the constriction ($\nu_{2}$) and bulk ($\nu_{1}$) regions. We develop a hydrodynamic theory for bosonic edge modes inspired by this model, finding that a competition between two tunneling process, related by a quasiparticle-quasihole symmetry, determines the fate of the low-bias transmission conductance. In this way, we find satisfactory explanations for many recent puzzling experimental results.Comment: 4 pages, 4 figure

Integrating Stakeholder Input into Water Policy Development and Analysis

Agricultural water use is becoming an issue in much of the South due to population growth. Results of projects evaluating the impacts of conservation strategies aimed at reallocating or extending the life of water supplies are being met with great skepticism by stakeholder groups. In order to gain acceptance of results, it is essential that stakeholder groups be involved from the beginning in the identification of potential water conservation strategies and be kept informed throughout the project. The objective of this paper is to review previous attempts at involving stakeholders and the methodology currently being employed in the Ogallala Aquifer Project.conservation, Ogallala Aquifer, stakeholder, water policy, Agribusiness, Agricultural and Food Policy, Consumer/Household Economics, Q250, Q280,

Reducing Irrigation Water Demand with Cotton Production in West Texas

Due to declining water availability from the Ogallala Aquifer and increasing pumping costs, irrigation management options for cotton are analyzed. The study concludes that supplemental irrigation while meeting crop ET requirements is the most profitable option. Switching from corn to cotton production may reduce irrigation water demand in the region.Ogallala Aquifer, irrigated cotton, irrigation efficiency, water response function, input use optimization, ET, Texas Panhandle, Crop Production/Industries, Resource /Energy Economics and Policy,

Increase in soil organic carbon by agricultural intensification in northern China

Acknowledgements. This research was supported by National Natural Science Foundation of China (no. 31370527 and 31261140367) and the National Science and Technology Support Program of China (no. 2012BAD14B01-2). The authors gratefully thank the Huantai Agricultural Station for providing of the Soil Fertility Survey data. We also thank Zheng Liang from China Agricultural University for the soil sampling and analysis in 2011. Thanks are extended to Jessica Bellarby for helpful discussion and suggestions.Peer reviewedPublisher PD

Phylogenetic analysis of Cryptosporidium isolates from captive reptiles using 18S rDNA sequence data and random amplified polymorphic DNA analys

Sequence alignment of a polymerase chain reaction-amplified 713-base pair region of the Cryptosporidium 18S rDNA gene was carried out on 15 captive reptile isolates from different geographic locations and compared to both Cryptosporidium parvum and Cryptosporidium muris isolates. Random amplified polymorphic DNA (RAPD) analysis was also performed on a smaller number of these samples. The data generated by both techniques were significantly correlated (P < 0.002), providing additional evidence to support the clonal population structure hypothesis for Cryptosporidium. Phylogenetic analysis of both 18S sequence information and RAPD analysis grouped the majority of reptile isolates together into 1 main group attributed to Cryptosporidium serpentis, which was genetically distinct but closely related to C. muris. A second genotype exhibited by 1 reptile isolate (S6) appeared to be intermediate between C. serpentis and C. muris but grouped most closely with C. muris, as it exhibited 99.15% similarity with C. muris and only 97.13% similarity with C. serpentis. The third genotype identified in 2 reptile isolates was a previously characterized 'mouse' genotype that grouped closely with bovine and human C. parvum isolates

Transport through constricted quantum Hall edge systems: beyond the quantum point contact

Motivated by surprises in recent experimental findings, we study transport in a model of a quantum Hall edge system with a gate-voltage controlled constriction. A finite backscattered current at finite edge-bias is explained from a Landauer-Buttiker analysis as arising from the splitting of edge current caused by the difference in the filling fractions of the bulk ($\nu_{1}$) and constriction ($\nu_{2}$) quantum Hall fluid regions. We develop a hydrodynamic theory for bosonic edge modes inspired by this model. The constriction region splits the incident long-wavelength chiral edge density-wave excitations among the transmitting and reflecting edge states encircling it. The competition between two interedge tunneling processes taking place inside the constriction, related by a quasiparticle-quasihole (qp-qh) symmetry, is accounted for by computing the boundary theories of the system. This competition is found to determine the strong coupling configuration of the system. A separatrix of qp-qh symmetric gapless critical states is found to lie between the relevant RG flows to a metallic and an insulating configuration of the constriction system. This constitutes an interesting generalisation of the Kane-Fisher quantum impurity model. The features of the RG phase diagram are also confirmed by computing various correlators and chiral linear conductances of the system. In this way, our results find excellent agreement with many recent puzzling experimental results for the cases of $\nu_{1}=1/3,~1$. We also discuss and make predictions for the case of a constriction system with $\nu_{2}=5/2$.Comment: 18 pages, 9 figure