Universality of Low-Energy Scattering in 2+1 Dimensions: The Non Symmetric Case

For a very large class of potentials, $V(\vec{x})$, $\vec{x}\in R^2$, we prove the universality of the low energy scattering amplitude, $f(\vec{k}', \vec{k})$. The result is $f=\sqrt{\frac{\pi}{2}}\{1/log k)+O(1/(log k)^2)$. The only exceptions occur if $V$ happens to have a zero energy bound state. Our new result includes as a special subclass the case of rotationally symmetric potentials, $V(|\vec{x}|)$.Comment: 65 pages, Latex, significant changes, new sections and appendice

Cornelius Lanczos's derivation of the usual action integral of classical electrodynamics

The usual action integral of classical electrodynamics is derived starting from Lanczos's electrodynamics -- a pure field theory in which charged particles are identified with singularities of the homogeneous Maxwell's equations interpreted as a generalization of the Cauchy-Riemann regularity conditions from complex to biquaternion functions of four complex variables. It is shown that contrary to the usual theory based on the inhomogeneous Maxwell's equations, in which charged particles are identified with the sources, there is no divergence in the self-interaction so that the mass is finite, and that the only approximation made in the derivation are the usual conditions required for the internal consistency of classical electrodynamics. Moreover, it is found that the radius of the boundary surface enclosing a singularity interpreted as an electron is on the same order as that of the hypothetical "bag" confining the quarks in a hadron, so that Lanczos's electrodynamics is engaging the reconsideration of many fundamental concepts related to the nature of elementary particles.Comment: 16 pages. Final version to be published in "Foundations of Physics

Time Evolution of Disease Spread on Networks with Degree Heterogeneity

Two crucial elements facilitate the understanding and control of communicable disease spread within a social setting. These components are, the underlying contact structure among individuals that determines the pattern of disease transmission; and the evolution of this pattern over time. Mathematical models of infectious diseases, which are in principle analytically tractable, use two general approaches to incorporate these elements. The first approach, generally known as compartmental modeling, addresses the time evolution of disease spread at the expense of simplifying the pattern of transmission. On the other hand, the second approach uses network theory to incorporate detailed information pertaining to the underlying contact structure among individuals. However, while providing accurate estimates on the final size of outbreaks/epidemics, this approach, in its current formalism, disregards the progression of time during outbreaks. So far, the only alternative that enables the integration of both aspects of disease spread simultaneously has been to abandon the analytical approach and rely on computer simulations. We offer a new analytical framework based on percolation theory, which incorporates both the complexity of contact network structure and the time progression of disease spread. Furthermore, we demonstrate that this framework is equally effective on finite- and "infinite"-size networks. Application of this formalism is not limited to disease spread; it can be equally applied to similar percolation phenomena on networks in other areas in science and technology.Comment: 20 pages, 6 figure

Tracking River Flows from Space

Satellite observations, combined with algorithms borrowed from river engineering, could fill large gaps in our knowledge of global river flows where field data are lacking

Round-Robin modelling of the load-bearing capacity of slender columns by using classical and advanced non-linear numerical and analytical prediction tools

Non-linear finite element analyses have intrinsic model and user factors that influence the results of the analyses. However, non-linear finite element analysis can provide a tool to assess safety using realistic descriptions of material behaviour with actual material properties. A realistic estimation of the existing safety and capacity of slender column elements can be achieved by means of "true" material properties. Nevertheless, it seems that for some structural components, such as slender columns, non-linear finite element analyses can, due to its complexity and its various setting parameters, cause the risk of overestimating the real performance of analysed components or systems. Hence, an invited expert group has carried out an investigation into the experimental testing and the prediction of the bearing capacity of slender columns by performing independent non-linear finite element analyses in order to determine the practical applicability, and its inconsistencies, with respect to the stability failure of slender columns. This work aims the characterization of modelling uncertainties, concerning the prediction of slender columns stability when forecasted by non-linear finite element analysis.This paper was partly carried out during research exchanges at TU Brno (BUT), Lehigh University (LU). The authors acknowledge also the financial support provided by the SAFEBRIDGE ATCZ190 EU Interreg project, the Scientific Grant Agency of the Ministry of Education of Slovak Republic, the Slovak Academy of Sciences VEGA No. 1/0696/14, and Slovak Research and Development Agency under the contract No. APVV-150658. The computational results presented have been achieved [in part] using the Vienna Scientific Cluster (VSC)

Susceptibility of rubber (Hevea brasiliensis) clones to Neofusicoccum ribis

The aim of this study was to evaluate the ability of Neofusicoccum ribis to infect leaf surfaces of different rubber (Hevea brasiliensis) clones. Neofusicoccum ribis isolates previously identified on the basis of morphological characteristics and DNA sequence analysis were used to inoculate rubber leaves and seedlings in vitro and in vivo respectively. Neofusicoccum ribis isolates were demonstrated to cause lesions on rubber clones examined in this study. There was variation in susceptibility of the rubber clones to the pathogen. This study provides useful information that could be exploited to better manage the disease

A Land Cover Map of Africa. Carte de l'Occupation du Sol de l'Afrique.

Abstract not availableJRC.H-Institute for environment and sustainability (Ispra

Bulk Metallic Glass based Tool-Making Process Chain for Micro- and Nano- Replication

Existing and emerging micro-engineered products tend to integrate a multitude of functionalities into single enclosures/packages. Such functions generally require different length scale features. In practice, devices having complex topographies, which incorporate different length scale features cannot be produced by employing a single fabrication technology but by innovatively, integrating several different complementary manufacturing techniques in the form of a process chain. In order to design novel process chains that enable such function and length scale integration into miniaturised devices, it is required to utilise materials that are compatible with the various component manufacturing processes in such chains. At the same time, these materials should be able to satisfy the functional requirements of the produced devices. One family of materials, which can potentially fulfil these criteria, is bulk metallic glasses (BMGs). In particular, the absence of grain boundaries in BMGs makes them mechanically and chemically homogeneous for processing at all length scales down to a few nanometres. In this context, this research presents an experimental study to validate a novel process chain. It utilizes three complementary technologies for producing a Zr-based BMG replication master for a microfluidic device that incorporates micro and nano scale features. Then, to validate the viability of the fabricated BMG masters, they are utilized for serial replication of the microfluidic device by employing micro-injection moulding