Crossover from quantum to Boltzmann transport in graphene

We compare a fully quantum mechanical numerical calculation of the conductivity of graphene to the semiclassical Boltzmann theory. Considering a disorder potential that is smooth on the scale of the lattice spacing, we find quantitative agreement between the two approaches away from the Dirac point. At the Dirac point the two theories are incompatible at weak disorder, although they may be compatible for strong disorder. Our numerical calculations provide a quantitative description of the full crossover between the quantum and semiclassical graphene transport regimes.Comment: 4 pages, 4 figures; published versio

Weyl node with random vector potential

We study Weyl semimetals in the presence of generic disorder, consisting of a random vector potential as well as a random scalar potential. We derive renormalization group flow equations to second order in the disorder strength. These flow equations predict a disorder-induced phase transition between a pseudo-ballistic weak-disorder phase and a diffusive strong-disorder phase for sufficiently strong random scalar potential or for a pure three-component random vector potential. We verify these predictions using a numerical study of the density of states near the Weyl point and of quantum transport properties at the Weyl point. In contrast, for a pure single-component random vector potential the diffusive strong-disorder phase is absent.Comment: published version with minor change

Quantifying the rural-urban gradient in Latin America and the Caribbean

This paper addresses the deceptively simple question: What is the rural population of Latin America and the Caribbean (LAC)? It argues that rurality is a gradient, not a dichotomy, and nominates two dimensions to that gradient: population density and remoteness from large metropolitan areas. It uses geographically referenced population data (from the Gridded Population of the World, version 3) to tabulate the distribution of populations in Latin America and in individual countries by population density and by remoteness. It finds that the popular perception of Latin America as a 75 percent urban continent is misleading. Official census criteria, though inconsistent between countries, tend to classify as"urban"small settlements of less than 2,000 people. Many of these settlements are however embedded in an agriculturally based countryside. The paper finds that about 13 percent of Latin America populations live at ultra-low densities of less than 20 per square kilometer. Essentially these people are more than an hour's distance from a large city, and more than half live more than four hours'distance. A quarter of the population of Latin America is estimated to live at densities below 50, again essentially all of them more than an hour's distance from a large city. Almost half (46 pecent) of Latin America live at population densities below 150 (a conventional threshold for urban areas), and more than 90 percent of this group is at least an hour's distance from a city; about one-third of them (18 percent of the total) are more than four hours distance from a large city.Agricultural Research,Demographics,Health Indicators,,Health Information&Communications Technologies

Ehrenfest-time dependence of weak localization in open quantum dots

Semiclassical theory predicts that the weak localization correction to the conductance of a ballistic chaotic cavity is suppressed if the Ehrenfest time exceeds the dwell time in the cavity [I. L. Aleiner and A. I. Larkin, Phys. Rev. B {\bf 54}, 14424 (1996)]. We report numerical simulations of weak localization in the open quantum kicked rotator that confirm this prediction. Our results disagree with the `effective random matrix theory' of transport through ballistic chaotic cavities.Comment: 4 pages, 2 figure

Automatic configuration of routing control platforms in OpenFlow networks

RouteFlow provides a way to run routing control platforms (e. g. Quagga) in OpenFlow networks. One of the issues of RouteFlow is that an administrator needs to devote a lot of time (typically 7 hours for 28 switches) in manual configurations. We propose and demonstrate a framework that can automatically configure RouteFlow. For this demonstration, we use an emulated pan-European topology of 28 switches. In the demonstration, we stream a video clip from a server to a remote client, and show that the video clip reaches at the remote client within 4 minutes (including the configuration time). In addition, we show automatic configuration of RouteFlow using a GUI (Graphical User Interface)

Sustaining a federation of future internet experimental facilities

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First report of multinodular pulmonary fibrosis associated with equine herpesvirus 5 in Belgium

A 20-year-old horse was evaluated for symptoms of weight loss, anorexia, fever and lethargy. Clinical examination revealed tachypnea, poor body condition and increased breath sounds on auscultation. Ultrasound showed multiple consolidations on the lungs. Thoracic radiography revealed a severe nodular pattern. The horse was treated with antibiotics, corticoids and supportive medication. Since no improvement was observed, the horse was euthanized. At necropsy, numerous coalescing fibrous nodules were present in the lungs. Histology revealed diffuse interstitial fibrosis and macrophages containing abundant eosinophilic cytoplasm and oval eosinophilic to amphophilic intranuclear inclusion bodies. Tissue samples tested positive for the presence of equine herpes virus 5 (EHV 5) on the basis of the polymerase chain reaction (PCR) test. A diagnosis of equine multinodular pulmonary fibrosis (EMPF) was made. This is the first report of EMPF in Belgium. EMPF can be suspected based on the ultrasonographic, radiographic and histological changes. EMPF is associated with EHV 5, but the etiological role of EHV 5 still remains to be proven