Roper Excitation in Alpha-Proton Scattering

We study the Roper excitation in the $(\alpha,\alpha')$ reaction. We consider all processes which may be relevant in the Roper excitation region, namely, Roper excitation in the target, Roper excitation in the projectile, and double $\Delta$ excitation processes. The theoretical investigation shows that the Roper excitation in the proton target mediated by an isoscalar exchange is the dominant mechanism in the process. We determine an effective isoscalar interaction by means of which the experimental cross section is well reproduced. This should be useful to make predictions in related reactions and is a first step to construct eventually a microscopic $NN \rightarrow NN^*$ transition potential, for which the present reaction does not offer enough information.Comment: Latex 17 pages; figures available by request; Phys. Rev. C in prin

Core regulatory network motif underlies the ocellar complex patterning in Drosophila melanogaster

arXiv:1404.4554v5During organogenesis, developmental programs governed by Gene Regulatory Networks (GRN) define the functionality, size and shape of the different constituents of living organisms. Robustness, thus, is an essential characteristic that GRNs need to fulfill in order to maintain viability and reproducibility in a species. In the present work we analyze the robustness of the patterning for the ocellar complex formation in Drosophila melanogaster fly. We have systematically pruned the GRN that drives the development of this visual system to obtain the minimum pathway able to satisfy this pattern. We found that the mechanism underlying the patterning obeys to the dynamics of a 3-nodes network motif with a double negative feedback loop fed by a morphogenetic gradient that triggers the inhibition in a French flag problem fashion. A Boolean modeling of the GRN confirms robustness in the patterning mechanism showing the same result for different network complexity levels. Interestingly, the network provides a steady state solution in the interocellar part of the patterning and an oscillatory regime in the ocelli. This theoretical result predicts that the ocellar pattern may underlie oscillatory dynamics in its genetic regulation.This work is partially financed by Junta de Andalucía (FQM-122) to A. Córdoba and by the Spanish Ministry for Science and Innovation (MICINN/MINECO) and Feder Funds through grants BFU2012-34324 to F. Casares (CABD, Seville, Spain) and Consolider Ingenio-2010 ‘From Genes to Shape’ (CSD 2007-008), of which F. Casares was a participant researcher.Peer Reviewe

Coherent pion production in neutrino nucleus collision in the 1 GeV region

We calculate cross sections for coherent pion production in nuclei induced by neutrinos and antineutrinos of the electron and muon type. The analogies and differences between this process and the related ones of coherent pion production induced by photons, or the (p,n) and $(^3 He, t)$ reactions are discussed. The process is one of the several ones occurring for intermediate energy neutrinos, to be considered when detecting atmospheric neutrinos. For this purpose the results shown here can be easily extrapolated to other energies and other nuclei.Comment: 13 pages, LaTex, 8 post-script figures available at [email protected]

Mantle melting and intraplate volcanism due to self‐buoyant hydrous upwellings from the stagnant slab that are conveyed by small‐scale convection

The mechanisms sustaining basaltic continental intraplate volcanism remain controversial. Continental intraplate volcanism is often geographically associated with slab stagnation in the mantle transition zone (MTZ), for example, in eastern Asia, central Europe, and western North America. Using 2‐D geodynamic models, we here explore the role of the stagnation of a slab and an associated hydrous layer in the MTZ on the formation and evolution of intraplate volcanism. Due to the intrinsic buoyancy of the hydrous layer atop the stagnant slab, upwellings develop within a few million years and rise to ~410‐km depth. At these depths, they partly lose their intrinsic buoyancy due to dehydration and stall intermittently. However, they are readily entrained by sublithospheric small‐scale convection to reach the base of lithosphere, sustaining mantle melting and intraplate volcanism. Water contents of >0.3 wt.‐% in a ≥ 60‐km‐thick layer atop the slab are sufficient for an early (<~20 Myr) onset of melting to account for volcanism, for example, in NE China. Thus, significant amounts of hydrous materials are not expected to remain stable in the MTZ for geological timescales, consistent with geophysical estimates. To explain the geochemical signatures of the Cenozoic basaltic volcanism in northern China, a mixed composition of the hydrous layer, including an enriched mantle‐type and a hybrid depleted mid‐ocean ridge basalts mantle/high μ‐type component, is required

Un instrumento de análisis para caracterizar el aprendizaje de la relación perímetro-área desde una perspectiva visual

La confusión entre magnitudes de naturaleza distinta constituye uno de los pilares problemáticos en el estudio de la medida. La falta de espacios que susciten la reflexión sobre relaciones entre magnitudes y el tratamiento de la medida desde una perspectiva netamente aritmética, y no cualitativa, son aspectos, entre otros, que explican tal deficiencia. En esta comunicación corta, la atención recae en las magnitudes área y perímetro. Por objetivo, se tiene, presentar un instrumento de análisis que caracterice cómo los estudiantes de grado quinto de primaria de dos instituciones educativas caleñas reaccionan ante la resolución de tareas que, desde una perspectiva visual (cualitativa), suscitan el estudio de la relación perímetro-área. En este orden de ideas, son cinco las categorías de análisis a discutir: operaciones, control, acciones, uso de elementos de control y dificultades. A manera de ejemplificación se caracteriza, según el modelo reseñado, el proceso de aprendizaje de uno de los estudiantes que participaron en la investigación

Analysis of polymorphisms in candidate’s genes for meat quality in Lidia cattle

The aim of this paper was to analyze the segregation of some polymorphisms in three genes ( CAPN1 , CAST and DGAT1 ) re- lated to meat quality in the Lidia cattle breed and some of its main lineages. To that effect, 119 individuals from the Lidia breed were analyzed. Although the association between the polymorphisms and the phenotype has never been demonstrated in this breed, the absence of fixed genotypes for these polymorphisms in the studied population makes the Lidia cattle a good candidate to de- velop selection objectives. The clear differentiation among lineages for most of the genes studied reinforces the high reproductive isolation presented in the Lidia cattle as revealed by previous studies on the structure of the population within the Lidia breed using microsatellite markers. Considering both issues in the design of breeding schemes will be necessary to save the lineages and not to lose this valuable genetic resource. Finally, it would be necessary to carry out an in depth search for new polymorphisms in genes associated with meat quality and to perform needed association analyses between the SNPs segregating in Lidia cattle and traits of economic interes

Analysis and optimisation of H2 production from crude glycerol by steam reforming using a novel two step process

This work studies the valorisation of biodiesel-derived glycerol to produce a hydrogen rich gas by means of a two-step sequential process. Firstly, the crude glycerol was purified with acetic acid to reduce problematical impurities. The effect of the final pH (5-7) on the neutralisation process was addressed and it was found that a pH of 6 provided the best phase separation and the greatest glycerol purity. Secondly, the refined glycerol was upgraded by catalytic steam reforming and this step was theoretically and experimentally studied. The theoretical study analyses the effect of the temperature (400-700°C), glycerol concentration (10-50 wt.%) and N2 (225-1347 cm3 STP/min) and liquid flow (0.5-1 mL/min) rates on the thermodynamic composition of the gas. The results show that the temperature and glycerol concentration exerted the greatest influence on the thermodynamics. The experimental study considers the effect of the temperature (400-700°C), glycerol concentration (10-50 wt.%) and spatial time (3-17 g catalyst min/g glycerol) on the product distribution in carbon basis (gas, liquid and solid) and on the composition of the gas and liquid phases. The experiments were planned according to a 2 level 3 factor Box-Wilson Central Composite Face Centred (CCF, a: ± 1) design, which is suitable for studying the influence of each variable as well as all the possible interactions between variables. The results were analysed with an analysis of variance (ANOVA) with 95% confidence, enabling the optimisation of the process. The gas phase was made up of a mixture of H2 (65-95 vol.%), CO2 (2-29 vol.%), CO (0-18 vol.%) and CH4 (0-5 vol.%). Temperatures of 550°C and above enabled thermodynamic compositions for the gas to be achieved and helped diminish carbon formation. A possible optimum for H2 production was found at a temperature of around 680°C, feeding a glycerol solution of 37 wt.% and using a spatial time of 3 g catalyst min/g glycerol. These conditions provide a 95% carbon conversion to gas, having the following composition: 67 vol.% H2, 22 vol.% CO2, 11 vol.% CO and 1 vol.% CH4