Total electron scattering cross sections from thiophene for the (1-300 eV) impact energy range

Experimental electron scattering cross sections for thiophene in the impact energy range from 1 to 300 eV have been measured with a magnetically confined electron transmission-beam apparatus. Random uncertainty limits have been estimated to be less than 5%, and systematic errors derived from acceptance angle limitations have also been identified and evaluated. Experimental values are compared with our previous low energy (1-15 eV) R-matrix and intermediate/high energy (15-300 eV) IAM-SCAR+I calculations finding reasonable agreement, within the combined uncertainty limits. Some of the low energy shape and core-excited resonances predicted by previous calculations are experimentally confirmed in this study

Tailor-made directional emission in nanoimprinted plasmonic-based light-emitting devices

We demonstrate an enhanced and tailor-made directional emission of light-emitting devices using nanoimprinted hexagonal arrays of aluminum nanoparticles. Fourier microscopy reveals that the luminescence of the device is not only determined by the material properties of the organic dye molecules but is also strongly influenced by the coherent scattering resulting from periodically arranged metal nanoparticles. Emitters can couple to lattice-induced hybrid plasmonic–photonic modes sustained by plasmonic arrays. Such modes enhance the spatial coherence of an emitting layer, allowing the efficient beaming of the emission along narrow angular and spectral ranges. We show that tailoring the separation of the nanoparticles in the array yields an accurate angular distribution of the emission. This combination of large-area metal nanostructures fabricated by nanoimprint lithography and light-emitting devices is beneficial for the design and optimization of solid-state lighting systems

Leptonic universality breaking in Upsilon decays as a probe of new physics

In this work we examine the possible existence of new physics beyond the standard model which could modify the branching fractions of the leptonic (mainly tauonic) decays of bottomonium vector resonances below the $B\bar{B}$ threshold. The decay width is factorized as the product of two pieces: a) the probability of an intermediate pseudoscalar color-singlet $b\bar{b}$ state (coupling to the dominant Fock state of the Upsilon via a magnetic dipole transition) and a soft (undetected) photon; b) the annihilation width of the $b\bar{b}$ pair into two leptons, mediated by a non-standard CP-odd Higgs boson of mass about 10 GeV, introducing a quadratic dependence on the lepton mass in the partial width. The process would be unwittingly ascribed to the $\Upsilon$ leptonic channel thereby (slightly) breaking lepton universality. A possible mixing of the pseudoscalar Higgs and bottomonium resonances is also considered. Finally, several experimental signatures to check out the validity of the conjecture are discussed.Comment: LaTeX, 22 pages, 2 EPS figure

Poisonous plants for cattle in Colombia: research perspectives

Even though Colombian cattle-farming makes an important contribution to the national economy it also has great potential for growth; however, this activity is carried out in areas where animals may become naturally exposed to poisonous plants, affecting their health and production. It is recognised that some plants may damage the livestock sector in countries placing an important emphasis on cattle-rearing. Such problem has received scarce attention from academic research in Colombia, and the efforts made to do so date from the 1930s, 1940s, 1970s and 1980s without having had continuity. Many of the studies done in Colombia have been orientated towards establishing nitrate and cyanogenic glycoside content, ignoring other toxic metabolites. Likewise, certain vegetal species which can cause poisoning have not been fully studied, thereby hampering their management and treatment. It is thus important that studies are carried out in greater depth in Colombia concerning poisonous plants affecting livestock. A methodology is thus proposed which includes a search for initial information about suspicious plants, reproducing such poisoning experimentally (selecting the animal species, route, presentation and administration time, and evaluating effects) and searching for the chemical responsible for causing the poisoning. All these aspects are dealt with in the present review.Además de un gran potencial de crecimiento, la ganadería bovina colombiana tiene un importante aporte a la economía nacional. Esta actividad se desarrolla en áreas donde los animales pueden exponerse naturalmente a plantas tóxicas, afectando su salud y producción. En países con una importante vocación ganadera se reconocen las plantas que pueden menoscabar el sector pecuario. En Colombia, escasamente ha sido estudiada esta problemática y los esfuerzos por hacerlo datan de las décadas de 1930, 1940, 1970 y 1980, sin que haya habido continuidad en los mismos. Muchos de los estudios realizados en el país han estado orientados a establecer el contenido de nitratos y glucósidos cianogénicos, ignorando otros metabolitos tóxicos. Así mismo, existen intoxicaciones por ciertas especies de vegetales que no han sido plenamente estudiadas, dificultando su manejo y tratamiento. Es importante que en el país se investigue con mayor profundidad sobre las plantas tóxicas de interés pecuario y para ello se propone una metodología que incluye selección de la planta sospechosa, reproducción experimental de la intoxicación (elección de la especie animal, vía, presentación y tiempo de administración y evaluación de efectos) y búsqueda de principios responsables de causar la intoxicación; estos aspectos se abordan en la presente revisión.Facultad de Ciencias Veterinaria

Poisonous plants for cattle in Colombia: research perspectives

Even though Colombian cattle-farming makes an important contribution to the national economy it also has great potential for growth; however, this activity is carried out in areas where animals may become naturally exposed to poisonous plants, affecting their health and production. It is recognised that some plants may damage the livestock sector in countries placing an important emphasis on cattle-rearing. Such problem has received scarce attention from academic research in Colombia, and the efforts made to do so date from the 1930s, 1940s, 1970s and 1980s without having had continuity. Many of the studies done in Colombia have been orientated towards establishing nitrate and cyanogenic glycoside content, ignoring other toxic metabolites. Likewise, certain vegetal species which can cause poisoning have not been fully studied, thereby hampering their management and treatment. It is thus important that studies are carried out in greater depth in Colombia concerning poisonous plants affecting livestock. A methodology is thus proposed which includes a search for initial information about suspicious plants, reproducing such poisoning experimentally (selecting the animal species, route, presentation and administration time, and evaluating effects) and searching for the chemical responsible for causing the poisoning. All these aspects are dealt with in the present review.Además de un gran potencial de crecimiento, la ganadería bovina colombiana tiene un importante aporte a la economía nacional. Esta actividad se desarrolla en áreas donde los animales pueden exponerse naturalmente a plantas tóxicas, afectando su salud y producción. En países con una importante vocación ganadera se reconocen las plantas que pueden menoscabar el sector pecuario. En Colombia, escasamente ha sido estudiada esta problemática y los esfuerzos por hacerlo datan de las décadas de 1930, 1940, 1970 y 1980, sin que haya habido continuidad en los mismos. Muchos de los estudios realizados en el país han estado orientados a establecer el contenido de nitratos y glucósidos cianogénicos, ignorando otros metabolitos tóxicos. Así mismo, existen intoxicaciones por ciertas especies de vegetales que no han sido plenamente estudiadas, dificultando su manejo y tratamiento. Es importante que en el país se investigue con mayor profundidad sobre las plantas tóxicas de interés pecuario y para ello se propone una metodología que incluye selección de la planta sospechosa, reproducción experimental de la intoxicación (elección de la especie animal, vía, presentación y tiempo de administración y evaluación de efectos) y búsqueda de principios responsables de causar la intoxicación; estos aspectos se abordan en la presente revisión.Facultad de Ciencias Veterinaria

Prime numbers, quantum field theory and the Goldbach conjecture

Motivated by the Goldbach conjecture in Number Theory and the abelian bosonization mechanism on a cylindrical two-dimensional spacetime we study the reconstruction of a real scalar field as a product of two real fermion (so-called \textit{prime}) fields whose Fourier expansion exclusively contains prime modes. We undertake the canonical quantization of such prime fields and construct the corresponding Fock space by introducing creation operators $b_{p}^{\dag}$ --labeled by prime numbers $p$-- acting on the vacuum. The analysis of our model, based on the standard rules of quantum field theory and the assumption of the Riemann hypothesis, allow us to prove that the theory is not renormalizable. We also comment on the potential consequences of this result concerning the validity or breakdown of the Goldbach conjecture for large integer numbers.Comment: 20 pages in A4 format, 2 figure

The Near-Horizon Limit of the Extreme Rotating d=5 Black Hole as a Homogenous Spacetime

We show that the spacetime of the near-horizon limit of the extreme rotating d=5 black hole, which is maximally supersymmetric in N=2,d=5 supergravity for any value of the rotation parameter j in [-1,1], is locally isomorphic to a homogeneous non-symmetric spacetime corresponding to an element of the 1-parameter family of coset spaces SO(2,1)x SO(3)/SO(2)_j in which the subgroup SO(2)_j is a combination of the two SO(2) subgroups of SO(2,1) and SO(3).Comment: Some points clarified and misprints corrected. Version to be published in Classical and Quantum Gravit