Inelastic electron backscattering in a generic helical edge channel

We evaluate the low-temperature conductance of a weakly interacting one-dimensional helical liquid without axial spin symmetry. The lack of that symmetry allows for inelastic backscattering of a single electron, accompanied by forward-scattering of another. This joint effect of weak interactions and potential scattering off impurities results in a temperature-dependent deviation from the quantized conductance, $\delta G \propto T^4$. In addition, $\delta G$ is sensitive to the position of the Fermi level. We determine numerically the parameters entering our generic model for the Bernevig-Hughes-Zhang Hamiltonian of a HgTe/CdTe quantum well in the presence of Rashba spin-orbit coupling.Comment: 4+ pages, 3 figures, published versio

Grandiose narcissism shapes counterfactual thinking (and regret):Direct and indirect evidence

Little is known about how individuals high in grandiose narcissism think about what could have been. Across four studies (three online surveys and one online experiment; N = 801), we addressed this gap by examining the relationship between grandiose narcissism, its admiration and rivalry dimensions, and counterfactual thinking and regret. Unlike anticipated, high rivalry was associated with more rather than fewer upward counterfactuals in Study 1. Yet, high rivalry predicted an increased likelihood of generating a downward (vs. upward) counterfactual in a feedback situation (Study 3). Moreover, grandiose narcissism (preliminary study) and admiration (Study 2) negatively correlated with regret. Collectively, our findings stress the importance of considering grandiose narcissism’s dimensions separately and highlight a novel dispositional moderator of counterfactual thinking

Compressive Sensing with Redundant Dictionaries and Structured Measurements

Consider the problem of recovering an unknown signal from undersampled measurements, given the knowledge that the signal has a sparse representation in a specified dictionary D. This problem is now understood to be well-posed and efficiently solvable under suitable assumptions on the measurements and dictionary, if the number of measurements scales roughly with the sparsity level. One sufficient condition for such is the D-restricted isometry property (D-RIP), which asks that the sampling matrix approximately preserve the norm of all signals which are sufficiently sparse in D. While many classes of random matrices are known to satisfy such conditions, such matrices are not representative of the structural constraints imposed by practical sensing systems. We close this gap in the theory by demonstrating that one can subsample a fixed orthogonal matrix in such a way that the D-RIP will hold, provided this basis is sufficiently incoherent with the sparsifying dictionary D. We also extend this analysis to allow for weighted sparse expansions. Consequently, we arrive at compressive sensing recovery guarantees for structured measurements and redundant dictionaries, opening the door to a wide array of practical applications

Diffuse Extragalactic Background Radiation

Attenuation of high--energy gamma rays by pair--production with UV, optical and IR background photons provides a link between the history of galaxy formation and high--energy astrophysics. We present results from our latest semi-analytic models (SAMs), based upon a $\Lambda$CDM hierarchical structural formation scenario and employing all ingredients thought to be important to galaxy formation and evolution, as well as reprocessing of starlight by dust to mid- and far-IR wavelengths. Our models also use results from recent hydrodynamic galaxy merger simulations. These latest SAMs are successful in reproducing a large variety of observational constraints such as number counts, luminosity and mass functions, and color bimodality. We have created 2 models that bracket the likely ranges of galaxy emissivities, and for each of these we show how the optical depth from pair--production is affected by redshift and gamma-ray energy. We conclude with a discussion of the implications of our work, and how the burgeoning science of gamma-ray astronomy will continue to help constrain cosmology.Comment: 12 pages, 8 figures, to be published in the Proceedings of the 4th Heidelberg International Symposium on High Energy Gamma-Ray Astronomy, held July 2008 in Heidelberg, German

Abundance and Distribution of Indo-Pacific Humpback Dolphins (Sousa Chinensis) in the Shimoni Archipelago, Kenya

This paper provides the first record of the distribution of Indo-Pacific humpback dolphins (Sousa chinensis) and an estimate of their abundance within the Shimoni Archipelogo, Kenya. Boat-based surveys (n=167) were conducted during 2006, using photographic identification (photo-id) techniques and mark-recapture methods for open populations (Jolly-Seber model) to estimate the abundance of humpback dolphins inhabiting the Wasini Channel (104: 95% CI 67-160). Their distribution was mapped within a 50% isopleth of encounter locations in the Wasini Channel, identified as the core habitat area. Most (97%) sightings were recorded outside the Kisite-Mpunguti Marine Protected Area (KMMPA). Further research is required but it is likely that the protection afforded by the Kenyan Wildlife Service (KWS) in their management of the KMMPA needs to be expanded to the Wasini Channel to ensure protection of the habitat of this small group of humpback dolphins

Long-term balancing selection drives evolution of immunity genes in Capsella.

Genetic drift is expected to remove polymorphism from populations over long periods of time, with the rate of polymorphism loss being accelerated when species experience strong reductions in population size. Adaptive forces that maintain genetic variation in populations, or balancing selection, might counteract this process. To understand the extent to which natural selection can drive the retention of genetic diversity, we document genomic variability after two parallel species-wide bottlenecks in the genus Capsella. We find that ancestral variation preferentially persists at immunity related loci, and that the same collection of alleles has been maintained in different lineages that have been separated for several million years. By reconstructing the evolution of the disease-related locus MLO2b, we find that divergence between ancient haplotypes can be obscured by referenced based re-sequencing methods, and that trans-specific alleles can encode substantially diverged protein sequences. Our data point to long-term balancing selection as an important factor shaping the genetics of immune systems in plants and as the predominant driver of genomic variability after a population bottleneck