Charge Fractionalization on Quantum Hall Edges

We discuss the propagation and fractionalization of localized charges on the edges of quantum Hall bars of variable widths, where interactions between the edges give rise to Luttinger liquid behavior with a non-trivial interaction parameter g. We focus in particular on the separation of an initial charge pulse into a sharply defined front charge and a broader tail. The front pulse describes an adiabatically dressed electron which carries a non-integer charge, which is \sqrt{g} times the electron charge. We discuss how the presence of this fractional charge can, in principle, be detected through measurements of the noise in the current created by tunneling of electrons into the system. The results are illustrated by numerical simulations of a simplified model of the Hall bar.Comment: 15 page

Seabird-Transported Contaminants Are Reflected in the Arctic Tundra, But Not in Its Soil-Dwelling Springtails (Collembola)

Arctic-breeding seabirds contain high levels of many anthropogenic contaminants, which they deposit through guano to the tundra near their colonies. Nutrient-rich soil in vicinity to seabird colonies are favorable habitats for soil invertebrates, such as springtails (Collembola), which may result in exposure to seabird-derived contaminants. We quantified a wide range of lipid-soluble and protein-associated environmental contaminants in two springtail species (Megaphorura arctica and Hypogastrura viatica) and their respective habitats (soil/moss) collected underneath seabird cliffs. Although springtails are commonly used in laboratory toxicity tests, this is the first study to measure concentrations of persistent organic pollutants (POPs) and mercury (Hg) in springtails from the field, and to study biotransportation of contaminants by seabirds to soil fauna. We categorized the sites a priori as of low, medium, or high seabird influence, based on the seabird abundance and species composition. This ranking was reflected in increasing δ15N values in soil/moss and springtails with increasing seabird influence. We found clear indications of seabirds impacting the terrestrial soil environments with organic contaminants, and that concentrations were higher in soil and moss close to the bird cliff, compared to farther away. However, we did not find a relationship between contaminant concentration in springtails and the concentrations in soil/moss, or with level of seabird influence. Our study indicates a low uptake of contaminants in the soil fauna, despite seabird-derived contamination of their habitat.publishedVersio

Transport of Babesia venatorum-infected Ixodes ricinus to Norway by northward migrating passerine birds

<p>Abstract</p> <p>Background</p> <p>Bovine babesiosis is regarded as a limited health problem for Norwegian cows, and the incidence has decreased markedly since the 1930s. Rare cases of babesiosis in splenectomised humans from infection with <it>Babesia divergens </it>and <it>B.venatorum </it>have been described. The objective of this study was to determine whether birds can introduce <it>Babesia</it>-infected ticks. There are between 30 and 85 million passerine birds that migrate to Norway every spring.</p> <p>Methods</p> <p>Passerine birds were examined for ticks at four bird observatories along the southern Norwegian coast during the spring migrations of 2003, 2004 and 2005. The presence of <it>Babesia </it>was detected in the nymphs of <it>Ixodes ricinus </it>by real-time PCR. Positive samples were confirmed using PCR, cloning and phylogenetic analyses.</p> <p>Results</p> <p>Of 512 ticks examined, real-time PCR revealed five to be positive (1.0%). Of these, four generated products that indicated the presence of <it>Babesia </it>spp.; each of these were confirmed to be from <it>Babesia venatorum </it>(EU1). Two of the four <it>B. venatorum</it>-positive ticks were caught from birds having an eastern migratory route (<it>P</it>< 0.001).</p> <p>Conclusions</p> <p>Birds transport millions of ticks across the North Sea, the Skagerrak and the Kattegat every year. Thus, even with the low prevalence of <it>Babesia</it>-infected ticks, a substantial number of infected ticks will be transported into Norway each year. Therefore, there is a continuous risk for introduction of new <it>Babesia </it>spp. into areas where <it>I. ricinus </it>can survive.</p

Detection of Babesia divergens in southern Norway by using an immunofluorescence antibody test in cow sera

<p>Abstract</p> <p>Background</p> <p>The incidence of bovine babesiosis, caused by <it>Babesia divergens </it>(Apicomplexa: Piroplasmida) has decreased markedly since the 1930 s, but may re-emerge as a consequence of climate change and changes in legislation and pasturing practices. This is a potentially serious disease, with both economical and animal welfare consequences. Therefore, there is a need to survey the distribution of <it>B. divergens</it>.</p> <p>Methods</p> <p>We tested sera from 306 healthy pastured cows from 24 farms along the southern Norwegian coast by using an indirect immunofluorescence IgG antibody test (IFAT). Fractions of seropositive cows were compared by calculating 95% CI.</p> <p>Results</p> <p>The results of this test showed that 27% of the sera were positive for <it>B. divergens </it>antibodies. The fraction of antibody-positive sera that we detected showed a two-humped distribution, with a high fraction of positives being found in municipalities in the western and eastern parts of the study area, while the municipalities between these areas had few or no positive serum samples.</p> <p>Conclusions</p> <p>Neither the farmers' observations nor the Norwegian Dairy Herd Recording System give an adequate picture of the distribution of bovine babesiosis. Serological testing of cows by using IFAT is a convenient way of screening for the presence of <it>B. divergens </it>in an area.</p

Hemispheric asymmetries in biodiversity : a serious matter of ecology

The original publication is available at http://www.plosbiology.orgPenguins have been receiving a lot of bad press lately. They are considered somehow counter, spare, strange. Unlike most plant and animal groups, they do not show a peak of species richness towards the equator and a decline towards the poles. This more conventional spatial pattern is conveniently known as the latitudinal diversity gradient because of the strong covariance of richness and other measures of biodiversity that it describes. It is one of the most venerable, well-documented, and controversial large-scale patterns in macroecology (Willig et al. 2003).Publishers' Versio

Latitudinal Variation in the Energy–Water Correlates for Species Richness

<p>Latitudinal distribution of energy–water correlates for species richness in which spatial variation in pure energy variables (closed bars), typically measured as temperature or potential evapotranspiration, or spatial variation in pure water availability variables (open bars), typically measured as rainfall or precipitation, best explains richness variation through space. Redrawn from <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020406#pbio-0020406-Hawkins1" target="_blank">Hawkins et al. (2003)</a>.</p

Number of Insect Species Pollinating Orchid Species in the Northern and Southern Hemispheres

<p>Europe and North America, closed bars, <i>n</i> = 41; southern Africa, open bars, <i>n</i> = 73. Redrawn from <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0020406#pbio-0020406-Johnson1" target="_blank">Johnson and Steiner (2003)</a>.</p

Temperature Variation with Latitude

<p>(A) Mean and absolute minimum and maximum temperatures across the New World.(B) Mean and absolute range in sea surface temperatures across the Pacific at 165° W.</p