Colour strings vs. hard pomeron in perturbative QCD

Average multiplicities and transverse momenta in AA collisions are studied in the soft and hard regions, in fusing string and perturbative QCD scenarios respectively. Striking similarities are found between the predictions of the two approaches. Multiplicities per string and average p_t^2 are found to, respectively, drop and rise with A in a very similar manner, so that their product is nearly a constant. In both approaches total multiplicities grow as A, that is as the number of participants. The high tail of the p_t distribution is found to behave as A^1.1 in the perturbative QCD scenario.Comment: 10 pages, 8 figure

ptp_t- dependence of the flow coefficients for pp collisions in the color string scenario. Monte-Carlo simulations

In the color string picture with fusion and percolation the dependence of the flow coefficients $v_n$ on the transverse momentum is studied for pp collisions the LHC energy respectively. Monte-Carlo simulations are used to locate simple strings and their fused clusters. The results favorably agree with the CMS data in the region $0.2 \le p_t\le 3.$ GeV/c appropriate for the string scenario.Comment: 10 pages, 6 figures. arXiv admin note: text overlap with arXiv:1407.459

Nuclear shuttling of key methionine cycle enzymes in acute liver injury

Artículo para la web de Divulgación Atlas of Science.Important metabolic enzymes have been classically ascribed to certain subcellular locations, where they perform their well-known function. In the last decades, several technological advances have allowed detection of these proteins in new locations, performing either their known catalytic role or a new function.Peer reviewe

Fusion of strings vs. percolation and the transition to the quark-gluon plasma

In most of the models of hadronic collisions the number of exchanged colour strings grows with energy and atomic numbers of the projectile and target. At high string densities interaction between them should melt them into the quark-gluon plasma state. It is shown that under certain assumptions about the the string interaction, a phase transition to the quark gluon plasma indeed takes place in the system of many colour strings. It may be of the first or second order (percolation), depending on the particular mechanism of the interaction. The critical string density is about unity in both cases. The critical density may have been already reached in central Pb-Pb collisions at 158 A GeV.Comment: 16 pages, 3 Postscript figure

Mejora del olmo para su resistencia contra los escolítidos

Dutch Elm Disease (DED) forms a complex system of three elements closely interacting: a host, a pathogen and an insect vector. Elm breeding programmes for resistance to DED have been exclusively based on selecting or obtaining pathogen-resistant trees, thus stressing only the host–pathogen side of the interaction and missing the vector component. Resistance against the bark beetle vectors would involve mechanisms other than those implicated in fungus resistance. As a consequence the search for resistance to the vectors would offer more than just a different way of obtaining resistant elms as it would allow incorporation of a new type of resistance into pathogen-resistant trees. Suppressing twig crotch feeding by elm bark beetles would greatly reduce infection on healthy elms. Evidence of preferences by elm bark beetles among different elm species has been documented in the field and in controlled experiments, demonstrating that U. minor is preferred over U. laevis and U. glabra, whereas intraspecific preferences among individual elms or clones remain largely unexplored. The selection of an individual plant by an insect is a two-step process that involves finding and accepting the host. Plant chemicals can play a key role in both of these steps, acting either as long-range stimuli, such as attractants or repellents, or as close-range contact cues, such as feeding stimulants and deterrents, operating after landing on the plant surface. Research on the chemical aspects of elm selection by bark beetles is here reviewed, and prospects for the future are discussed.La enfermedad de la grafiosis de los olmos constituye un sistema formado por tres elementos estrechamente relacionados: un hospedante, un patógeno y un insecto vector. Los programas de mejora de olmos frente a la grafiosis se han basado en seleccionar u obtener árboles resistentes al patógeno, poniendo el énfasis sólo en la parte patógenohospedante de la interacción y olvidándose del componente vector. La resistencia frente a los escolítidos vectores supondría mecanismos distintos de aquéllos implicados en la resistencia frente al hongo. Como consecuencia, la búsqueda de resistencia frente a los vectores ofrecería no sólo una via diferente de obtener olmos resistentes, sino además la posibilidad de incorporar un nuevo tipo de resistencia a los árboles resistentes al patógeno. La supresión de la alimentación en las ramillas por los escolítidos del olmo reduciría notablemente la infección en los olmos sanos. La evidencia de preferencias en los escolítidos del olmo entre especies diferentes de olmos ha sido documentada en el campo y en experimentos controlados, demostrándose que U. minor es más preferido que U. laevis o que U. glabra, si bien, la existencia de preferencias intraespecíficas entre árboles o clones permanece inexplorada. La selección de una determinada planta por un insecto es un proceso doble que supone encontrar y aceptar al hospedante. Los compuestos químicos vegetales pueden representar un papel clave en ambas fases, actuando bien como estímulos a larga distancia, tales como atrayentes o repelentes, o bien como señales a corta distancia, tales como fagoestimulantes o fagodisuasores, que operan después del aterrizaje sobre la superficie vegetal. Se revisa aquí la investigación sobre los aspectos químicos en la selección de los olmos por los escolítidos y se discuten las perspectivas futuras