Experimental progress towards probing the ground state of an electron-hole bilayer by low-temperature transport

Recently, it has been possible to design independently contacted electron-hole bilayers (EHBLs) with carrierdensities  cm2 in each layer and a separation of 10–20 nm in a GaAs/AlGaAs system. In these EHBLs,the interlayer interaction can be stronger than the intralayer interactions. Theoretical works have indicated thepossibility of a very rich phase diagram in EHBLs consisting of excitonic superfluid phases, charge densitywaves, and Wigner crystals. Experiments have revealed that the Coulomb drag on the hole layer shows strongnonmonotonic deviations from a behaviour expected for Fermi-liquids at low temperatures. Simultaneously,an unexpected insulating behaviour in the single-layer resistances (at a highly “metallic” regime with) also appears in both layers despite electron mobilities of above and hole mobilitiesover . Experimental data also indicates that the point of equal densities () is not special.Peer Reviewe

Quantum condensation in electron-hole bilayers with density imbalance

We study the two-dimensional spatially separated electron-hole system with density imbalance at absolute zero temperature. By means of the mean-field theory, we find that the Fulde-Ferrell state is fairly stabilized by the order parameter mixing effect.Comment: 5 pages, 5 figure

Functional analysis and expression profiling of HcrVf1 and HcrVf2 for development of scab resistant cisgenic and intragenic apples

Apple scab resistance genes, HcrVf1 and HcrVf2, were isolated including their native promoter, coding and terminator sequences. Two fragment lengths (short and long) of the native gene promoters and the strong apple rubisco gene promoter (PMdRbc) were used for both HcrVf genes to test their effect on expression and phenotype. The scab susceptible cultivar ‘Gala’ was used for plant transformations and after selection of transformants, they were micrografted onto apple seedling rootstocks for scab disease tests. Apple transformants were also tested for HcrVf expression by quantitative RT-PCR (qRT-PCR). For HcrVf1 the long native promoter gave significantly higher expression that the short one; in case of HcrVf2 the difference between the two was not significant. The apple rubisco gene promoter proved to give the highest expression of both HcrVf1 and HcrVf2. The top four expanding leaves were used initially for inoculation with monoconidial isolate EU-B05 which belongs to race 1 of V. inaequalis. Later six other V. inaequalis isolates were used to study the resistance spectra of the individual HcrVf genes. The scab disease assays showed that HcrVf1 did not give resistance against any of the isolates tested regardless of the expression level. The HcrVf2 gene appeared to be the only functional gene for resistance against Vf avirulent isolates of V. inaequalis. HcrVf2 did not provide any resistance to Vf virulent strains, even not in case of overexpression. In conclusion, transformants carrying the apple-derived HcrVf2 gene in a cisgenic as well as in an intragenic configuration were able to reach scab resistance levels comparable to the Vf resistant control cultivar obtained by classical breeding, cv. ‘Santana’

Data set accompanying the letter "A complete laboratory for transport studies of electron-hole interactions in GaAs/AlGaAs ambipolar bilayers"

Coulomb drag and magnetotransport data from the ambipolar GaAs/AlGaAs 2D bilayer devices described in the associated publication, measured by the authors at the Cavendish Laboratory, University of Cambridge UK, in the period October 2013 to April 2016. The data were measured at low temperature (90 mK to 4 K). The experimental methods are described in the associated publication

Identifying the origins of fishing gear ingested by seabirds: a novel multivariate approach

* 1. The global decline of albatrosses (Diomedidae: Procellariiformes) is thought to have occurred largely as a direct result of fishery-related mortality. Albatrosses and other large petrels interact with fisheries in several ways, including scavenging used bait and discarded offal, which may contain hooks. * 2. Hooks that are ingested by breeding birds are often fed to chicks which subsequently regurgitate them shortly before fledging. * 3. In this study a series of mathematical (cladistic, cluster and principal components) analyses are applied to a sample of 241 items of fishing gear (hook, snood and hook/snood unit) collected from seabird nest sites on Bird Island, South Georgia, and 44 reference gear items provided by four South Atlantic regional fisheries. * 4. The five separate analyses failed to assign most gear to a particular fishery or to identify any consistent annual trends. The homogeneous nature of the material, which was largely derived from the same manufacturers, meant that gear origin could not be determined. This suggests that hooks found at seabird colonies in this, and potentially other regions, will be of limited use in identifying offending fisheries, unless operators are obliged to deploy gear with unique marks in the future. * 5. Nevertheless, it is suggested that this approach should work effectively where birds interact with a range of fisheries targeting different species using variable gear. This study therefore represents an innovative approach to the characterization of lost fishing gear with potentially widespread application. Copyright © 2010 John Wiley & Sons, Ltd