Interfacial depinning transitions in disordered media: revisiting an old puzzle

Interfaces advancing through random media represent a number of different problems in physics, biology and other disciplines. Here, we study the pinning/depinning transition of the prototypical non-equilibrium interfacial model, i.e. the Kardar-Parisi-Zhang equation, advancing in a disordered medium. We analyze separately the cases of positive and negative non-linearity coefficients, which are believed to exhibit qualitatively different behavior: the positive case shows a continuous transition that can be related to directed-percolation-depinning while in the negative case there is a discontinuous transition and faceted interfaces appear. Some studies have argued from different perspectives that both cases share the same universal behavior. Here, by using a number of computational and scaling techniques we shed light on this puzzling situation and conclude that the two cases are intrinsically different.Comment: 13 pages, 9 figure

Optical Transistor for an Amplification of Radiation in a Broadband THz Domain

We propose a new type of optical transistor for a broadband amplification of THz radiation. It is made of a graphene--superconductor hybrid, where electrons and Cooper pairs couple by Coulomb forces. The transistor operates via the propagation of surface plasmons in both layers, and the origin of amplification is the quantum capacitance of graphene. It leads to THz waves amplification, the negative power absorption, and as a result, the system yields positive gain, and the hybrid acts like an optical transistor, operating with the terahertz light. It can, in principle, amplify even a whole spectrum of chaotic signals (or noise), that is required for numerous biological applications.Comment: 7 pages, 3 figure

Mechanism for flux guidance by micrometric antidot arrays in superconducting films

A study of magnetic flux penetration in a superconducting film patterned with arrays of micron sized antidots (microholes) is reported. Magneto-optical imaging (MOI) of a YBCO film shaped as a long strip with perpendicular antidot arrays revealed both strong guidance of flux, and at the same time large perturbations of the overall flux penetration and flow of current. These results are compared with a numerical flux creep simulation of a thin superconductor with the same antidot pattern. To perform calculations on such a complex geometry, an efficient numerical scheme for handling the boundary conditions of the antidots and the nonlocal electrodynamics was developed. The simulations reproduce essentially all features of the MOI results. In addition, the numerical results give insight into all other key quantities, e.g., the electrical field, which becomes extremely large in the narrow channels connecting the antidots.Comment: 8 pages, 7 figure

StMoMo: An R Package for Stochastic Mortality Modelling

In this paper we mirror the framework of generalised (non-)linear models to define the family of generalised Age-Period-Cohort stochastic mortality models which encompasses the vast majority of stochastic mortality projection models proposed to date, including the well-known Lee-Carter and Cairns-Blake-Dowd models. We also introduce the R package StMoMo which exploits the unifying framework of the generalised Age-Period-Cohort family to provide tools for fitting stochastic mortality models, assessing their goodness of fit and performing mortality projections. We illustrate some of the capabilities of the package by performing a comparison of several stochastic mortality models applied to the England and Wales population

Effect of Uropathogenic <i>Escherichia coli</i> on Human Sperm Function and Male Fertility

Infections of the reproductive tract represent nearly 15% of male infertility cases. The most frequently isolated bacterium in the ejaculate of infertile men is Escherichia coli (E. coli), which causes between 60 and 85% of cases of chronic bacterial prostatitis leading to sperm damage. The aim of this chapter is to discuss the negative effects of E. coli on sperm quality and male fertility. The E. coli isolated from semen is uropathogenic (UPEC) and can damage sperm in different ways. UPEC induces activation of polymorphonuclear leukocytes with the release of cytokines and reactive oxygen species, the latter being harmful due to their ability to induce lipid peroxidation and early sperm capacitation. Also, UPEC decreases sperm motility, vitality and mitochondrial membrane potential through direct contact or mediated by its soluble metabolites. The negative effects are higher with strains with specific characteristics such as hemolytic capacity. In vivo studies with mice models have shown that UPEC inoculated into the epididymis induces inflammatory damage with testicular mass decrease and low sperm concentration. Future studies are needed to clarify the molecular mechanisms by which E. coli damages sperm. This knowledge will make it possible to take measures to avoid deleterious consequences on the fertilizing potential of men

The Impact of Foreign Direct Investment on Developing Economies and the Environment

This article is about the impact of foreign direct investment on developing economies and the environment. All of us that are concerned about the environment should ask ourselves if the increase in capital mobility associated with the world-wide process of liberalization, deregulation and privatization, known as the Neo-liberal global regime, has contributed to the problems of higher emissions, ozone layer destruction, and pollution of water sources, as well as to create false economic bubbles that lead to increased consumption in these regions whilst forcing the destruction of the environment by the poor in order to survive and cope with the roles their society demands. Neo-liberal practices such as those enforced in developing countries like Colombia, while seeking to attract foreign investment to push their economies, tend to generate a false aggregated demand growth that in most cases is not sustainable in the long term, increases global unemployment, unleash destructive competitive processes and weaken government’s ability to regulate business in the citizens` best interests.Este artículo trata sobre el impacto de inversión extranjera directa en economías en vías de desarrollo y el medio ambiente. Todos los que nos preocupamos por el medio ambiente debemos preguntarnos, si el aumento en la movilidad de capitales asociada con el proceso mundial de liberalización, desregulación y privatización, conocido como “neoliberalismo”, ha contribuido a problemas de emisiones más altas, destrucción de la capa de ozono, y polución de fuentes de agua, así como a la creación de falsas burbujas económicas que llevan a aumentar el consumo en estas regiones, obligando a los más pobres a destruir el medio ambiente para sobrevivir y poder cumplir con los roles impuestos por la sociedad. Prácticas neoliberales tales como las implantadas en países en vías de desarrollo, como Colombia, en búsqueda de alcanzar mayor inversión extranjera para impulsar sus economías, tienden a generar un falso crecimiento de la demanda agregada que en la mayoría de los casos no es sostenible en el largo plazo, y generan así alto desempleo, procesos competitivos destructivos, y debilitando la habilidad de los gobiernos de regular los negocios y salvaguardar los intereses de los ciudadanos

Unusual magneto-transport of YBa2Cu3O7-d films due to the interplay of anisotropy, random disorder and nanoscale periodic pinning

We study the general problem of a manifold of interacting elastic lines whose spatial correlations are strongly affected by the competition between random and ordered pinning. This is done through magneto-transport experiments with YBa2Cu3O7-d thin films that contain a periodic vortex pinning array created via masked ion irradiation, in addition to the native random pinning. The strong field-matching effects we observe suggest the prevalence of periodic pinning, and indicate that at the matching field each vortex line is bound to an artificial pinning site. However, the vortex-glass transition dimensionality, quasi-2D instead of the usual 3D, evidences reduced vortex-glass correlations along the vortex line. This is also supported by an unusual angular dependence of the magneto-resistance, which greatly differs from that of Bose-glass systems. A quantitative analysis of the angular magnetoresistance allows us to link this behaviour to the enhancement of the system anisotropy, a collateral effect of the ion irradiation

The Impact of Foreign Direct Investment on Developing Economies and the Environment

This article is about the impact of foreign direct investment on developing economies and the environment. All of us that are concerned about the environment should ask ourselves if the increase in capital mobility associated with the world-wide process of  liberalization, deregulation and privatization, known as the Neo-liberal global regime, has contributed to the problems of higher emissions, ozone layer destruction, and pollution of water sources, as well as to create false economic bubbles that lead to increased consumption in these regions whilst forcing the destruction of the environment by the poor in order to survive and cope with the roles their society demands. Neo-liberal practices such as those enforced in developing countries like Colombia, while seeking to attract foreign investment to push their economies, tend to generate a false aggregated demand growth that in most cases is not sustainable in the long term, increases global unemployment, unleash destructive competitive processes and weaken government’s ability to regulate business in the citizens` best interests.Este artículo trata sobre el impacto de inversión extranjera directa en economíasen vías de desarrollo y el medio ambiente. Todos los que nos preocupamos por elmedio ambiente debemos preguntarnos, si el aumento en la movilidad de capitales asociada con el proceso mundial de liberalización, desregulación y privatización,conocido como “neoliberalismo”, ha contribuido a problemas de emisiones másaltas, destrucción de la capa de ozono, y polución de fuentes de agua, así como a lacreación de falsas burbujas económicas que llevan a aumentar el consumo en estasregiones, obligando a los más pobres a destruir el medio ambiente para sobrevivir ypoder cumplir con los roles impuestos por la sociedad. Prácticas neoliberales talescomo las implantadas en países en vías de desarrollo, como Colombia, en busquedade alcanzar mayor inversión extranjera para impulsar sus economías, tienden agenerar un falso crecimiento de la demanda agregada que en la mayoría de loscasos no es sostenible en el largo plazo, y generan así alto desempleo, procesoscompetitivos destructivos, y debilitando la habilidad de los gobiernos de regular losnegocios y salvaguardar los intereses de los ciudadanos