Four-body continuum-discretized coupled-channels calculations: Application to 6He+64Zn at 13.6 MeV

The recently developed four-body continuum-discretized coupled-channels (CDCC) method, making use of the binning procedure [1], is applied to the reaction 6He+64Zn at 13.6 MeV (around the Coulomb barrier). Excellent agreement with available elastic data [2] is found.Dirección General de Investigación Científica y Técnica FIS 2008-04189, FPA 2006- 13807-C02-01U.S. Department of Energy DE-AC52-07NA27344U.K. STFC EP/D00362

Resonant breakup of 19C on a proton target

The resonant breakup of 19C on a proton target at 70 MeV/nucleon is analyzed using Faddeev-Alt, Grassberger, Sandhas (Faddeev-AGS) and continuum-discretized coupled-channels (CDCC) reaction frameworks, where in both cases a three-body model (18C+n+p) for the reaction is considered. Taking a 18C + p potential from a global nucleon-nucleus parametrization and a L-independent Gaussian proton-neutron potential, both methods provide very similar results for the calculated observables. However, when this simplified proton-neutron potential is replaced by the more realistic CD-Bonn potential, the breakup cross section, calculated with the Faddeev AGS formalism, decreases by almost one order of magnitude, largely underestimating the experimental data. From this calculation, we conclude that, within a core + valence neutron model, the single-particle mechanism gives a negligible contribution to the calculated resonant breakup and therefore core-excitation mechanisms should be taken into account.Ministerio de Ciencia e Innovación (España) FPA2009-0765

Functional statistical techniques applies to vine leaf water content

P. 1116-1122A statistical analysis of functional data, obtained as reflectance values measured using a hyperspectral sensor, was used to determine water content in vine leaves. Our study was conducted using a sample of 80 vine leaves whose water content was determined by calculating the weight difference between leaves before and after drying in an oven.S

Rare Events and Scale--Invariant Dynamics of Perturbations in Delayed Dynamical Systems

We study the dynamics of perturbations in time delayed dynamical systems. Using a suitable space-time coordinate transformation, we find that the time evolution of the linearized perturbations (Lyapunov vector) can be mapped to the linear Zhang surface growth model [Y.-C. Zhang, J. Phys. France {\bf 51}, 2129 (1990)], which is known to describe surface roughening driven by power-law distributed noise. As a consequence, Lyapunov vector dynamics is dominated by rare random events that lead to non-Gaussian fluctuations and multiscaling properties.Comment: Final version to appear in Phys. Rev. Lett., 4 pages, 3 eps fig

α-SNAP Prevents Docking of the Acrosome during Sperm Exocytosis because It Sequesters Monomeric Syntaxin

α-SNAP has an essential role in membrane fusion that consists of bridging cis SNARE complexes to NSF. α-SNAP stimulates NSF, which releases itself, α-SNAP, and individual SNAREs that subsequently re-engage in the trans arrays indispensable for fusion. α-SNAP also binds monomeric syntaxin and NSF disengages the α-SNAP/syntaxin dimer. Here, we examine why recombinant α-SNAP blocks secretion in permeabilized human sperm despite the fact that the endogenous protein is essential for membrane fusion. The only mammalian organism with a genetically modified α-SNAP is the hyh mouse strain, which bears a M105I point mutation; males are subfertile due to defective sperm exocytosis. We report here that recombinant α-SNAP-M105I has greater affinity for the cytosolic portion of immunoprecipitated syntaxin than the wild type protein and in consequence NSF is less efficient in releasing the mutant. α-SNAP-M105I is a more potent sperm exocytosis blocker than the wild type and requires higher concentrations of NSF to rescue its effect. Unlike other fusion scenarios where SNAREs are subjected to an assembly/disassembly cycle, the fusion machinery in sperm is tuned so that SNAREs progress uni-directionally from a cis configuration in resting cells to monomeric and subsequently trans arrays in cells challenged with exocytosis inducers. By means of functional and indirect immunofluorescense assays, we show that recombinant α-SNAPs — wild type and M105I — inhibit exocytosis because they bind monomeric syntaxin and prevent this SNARE from assembling with its cognates in trans. Sequestration of free syntaxin impedes docking of the acrosome to the plasma membrane assessed by transmission electron microscopy. The N-terminal deletion mutant α-SNAP-(160–295), unable to bind syntaxin, affects neither docking nor secretion. The implications of this study are twofold: our findings explain the fertility defect of hyh mice and indicate that assembly of SNAREs in trans complexes is essential for docking

The Research Program at RIBRAS (Radioactive Ion Beams in Brasil)-III

A part of the research program developed in the RIBRAS facility over the last four years is presented. Experiments using radioactive secondary beams of light exotic nuclei such as 6He, 7Be, 8Li on several targets have been performed. Elastic angular distributions have been analysed by the Optical Model and four body Continuous Discretized Coupled Channels Calculations (4b-CDCC) and the total reaction cross sections have been obtained. A comparison between the reaction cross sections of 6He and other stable projectiles with medium-heavy targets was performed. Measurements of the proton transfer reaction 12C(8Li,9Be)11B are also presented

Exotic Nuclei in South America

The Radioactive Ion Beams in Brasil (RIBRAS) is described. Experiments using radioactive secondary beams of light rare isotopes such as 6He, 7Be, 8Li on several targets have been performed and the results are presented

Enhancing the hydrogen transfer catalytic activity of hybrid carbon nanotube-based NHC–iridium catalysts by increasing the oxidation degree of the nanosupport

CVD-grown multiwalled carbon nanotubes were purified by applying four different treatments with increasing oxidation severity. The growing severity of the treatment results in progressive oxygen functionalization of the surface along with introduction of an increasing quantity of defects on the carbon nanotube walls. Iridium-N-heterocyclic carbene complexes were covalently anchored to those oxidized surfaces through their surface carboxylic acids via acetyl linkers. The carbon nanotube-based iridium-NHC hybrid materials developed are active in the hydrogen-transfer reduction of cyclohexanone to cyclohexanol with 2-propanol/KOH as hydrogen source but with rather different activity. The catalytic activity of the hybrid catalysts is strongly influenced by the type and amount of oxygenated functionalization resulting from the treatment applied to the support, being the most active and the most oxidized material.The authors thank the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) (Projects Consolider Ingenio 2010 CSD2009-00050 and CTQ2013-42532-P) and the Diputación General de Aragón (FSE-E07 and FSE-E69) for their financial support. Dr. P. A. thanks MINECO for a Ramón y Cajal contract. M. B. acknowledges his fellowship from MECD (AP2010-0025).Peer Reviewe

Optimización de Scaled Conjugate Gradient para Froog Neural Networks

El Scaled Conjugate Gradient es un algoritmo de aprendizaje iterativo para redes neuronales artificiales, destacándose por su velocidad de convergencia frente al Backpropagation. Esto se debe a que utiliza derivadas de segundo orden, lo que permite una convergencia más veloz. En este artículo, se demuestra lo expuesto por Möller en su trabajo original, respecto a que una adecuada implementación del Scaled Conjugate Gradient puede reducir en un 50% el tiempo de ejecución. La implementación fue realizada en la herramienta gratuita "Froog Neural Networks" de redes neuronales y probada en 4 base de datos estándar, con diferentes cantidades de neuronas para probar la efectividad de los cambios realizados.Sociedad Argentina de Informática e Investigación Operativ

Catalytic activity of iridium NHC complexes covalently bonded to carbon nanotubes and graphene oxide

Trabajo presentado a la Annual World Conference on Carbon, celebrada en Dresden (Alemania) del 12 al 17 de julio de 2015.Carbon nanotubes and graphene have been extensively applied as proactive supports to generate heterogeneous catalysts. Both exhibit a carbon structure composed by carbon atoms with sp2 hybridization and both are used in similar applications, as in catalysis. However, the role of each particular substrate, determined by its structural peculiarities, can be differentvshould be studied for each particular catalytic reaction and in their structure.The aim of this work is to study the differences between oxidized carbon nanotubes (CNT) and graphene oxides (GO) as proactive supports of iridium Nheterocyclic carbene (NHC) catalyst. The effect of their inherent structure in the catalytic activity in hydrogen transfer reactions was studied in detail.The authors thank MINECO/MECD (Projects CONSOLIDER INGENIO 2010 CSD2009-00050, CTQ 2010-15221, Ramón y Cajal contract of P. Alvarez and fellowship of M. Blanco) and the Diputación General de Aragón (E07) for their financial support.Peer Reviewe