Long range absorption in the scattering of 6He on 208Pb and 197Au at 27 MeV

Quasi-elastic scattering of 6He at E_lab=27 MeV from 197Au has been measured in the angular range of 6-72 degrees in the laboratory system employing LEDA and LAMP detection systems. These data, along with previously analysed data of 6He + 208Pb at the same energy, are analyzed using Optical Model calculations. The role of Coulomb dipole polarizability has been investigated. Large imaginary diffuseness parameters are required to fit the data. This result is an evidence for long range absorption mechanisms in 6He induced reactions.Comment: 10 pages, 10 figures, minor corrections. To appear in Nucl. Phys.

Legacy of landscape crop diversity enhances carabid beetle species richness and promotes granivores

It is well understood that agricultural expansion and associated loss of semi-natural habitat in the landscape are major drivers for the marked decline in biodiversity. While conserving remaining semi-natural habitat patches is essential to reverse ongoing biodiversity declines, increasing focus has also been put on diversifying cropland itself by increasing landscape crop diversity as a measure of compositional heterogeneity, and reducing field sizes as a measure of configurational heterogeneity. Both these cropland diversification approaches have shown promise to enhance biodiversity in the year of sampling, but it is unknown whether legacies of crop diversity in the landscape promote biodiversity by building up arthropod communities over time. We selected 14 faba bean fields in landscapes dominated by cropland. The fields were chosen along three gradients: landscape crop di-versity of the year of sampling (2017), landscape crop diversity of the previous year (2016) and mean field size in landscapes. Using pitfall traps, we show that the carabid beetle species richness is higher in landscapes with higher crop diversity in the previous year. Especially, granivorous carabid beetles benefitted from legacies of crop diversity. Rove beetles were more abundant and genus rich in landscapes with larger field sizes, while spiders were not responding to any of the landscape variables. A diversity of crops in the landscape and their associated weed communities could provide more diverse food resources and shelter habitats, which build populations of carabid beetle species over time. There is a need to explore the effects of agri-environmental schemes across multiple years to better understand legacy effects, and to structure sustainable agricultural landscapes

Transversalidad de las técnicas de modelado matemático en Farmacia con la ayuda de una hoja de cálculo

The implementation of the EHEA in Pharmacy studies will lead to foster student self-learning. This way the student abilities to apply knowledge, learned in some subjects, to search knowledge in any other will be tested. Among such applicative knowledge, we can consider the mathematical modelling techniques, included in the field of Mathematics. This article draws attention to the usefulness of popular spreadsheets for Pharmacy students interested in the application of mathematical modelling techniques. Roughly speaking, a pharmacy student will probably have to perform mathematical calculations and experimental data visualizations, especially in the practice syllabus of some of his subjects. The use of software is important in this respect, not only in the learning step of the mathematical concepts in the corresponding math subject, but also in its application to other Pharmacy subjects. What application software can be chosen for the students? Although there are many candidates, a spreadsheet offers some capabilities that make it ideal for a Pharmacy student: short learning time, wide availability on different computer platforms and flexibility to carry out a variety of computational tasks. Finally, we present a Web page which provides self-learning material to Pharmacy students for harnessing the potential offered by the spreadsheets Excel (Microsoft Office) and Calc (OpenOffice.org) in the study of their subjects in Pharmacy.La implantación del EEES en las titulaciones en Farmacia va a significar la potenciación del autoaprendizaje por parte del alumno. Esto va a poner a prueba la capacidad de aplicar conocimientos adquiridos en unas materias, para entender y conocer otras. Entre dichos conocimientos, se encuentran las técnicas de modelado matemático, incluidas en el campo de las Matemáticas. El presente artículo reflexiona acerca de la utilidad de las populares hojas de cálculo como software dirigido al alumno. Un alumno de Farmacia, probablemente, tendrá que realizar cálculos matemáticos y representaciones gráficas con datos experimentales, muy especialmente en las prácticas de algunas de sus asignaturas. La utilización de un software es, en este sentido, especialmente importante, no sólo en la fase de aprendizaje de dichos conocimientos matemáticos en la correspondiente asignatura del título, sino a la hora de disponer de una herramienta que facilite su aplicación en otras. ¿Qué software podemos elegir para el alumno? A pesar de que existen multitud de candidatos, una hoja de cálculo reúne una serie de características que la hacen idónea para un alumno de Farmacia: corto tiempo de aprendizaje, amplia disponibilidad en distintas plataformas y flexibilidad para poder realizar una gran diversidad de tareas, entre otras propiedades. Finalmente, como ejemplo se presenta una página Web, http://www.ugr.es/~focana/farmaspreadsheet.htm, que facilita material para ayudar al alumno de Farmacia a aprovechar las posibilidades que ofrecen las hojas de cálculo Excel (Microsoft Office) y Calc (OpenOffice.org) en el estudio de sus asignaturas en Farmacia

Transfer to the continuum and Breakup reactions

Reaction theory is an essential ingredient when performing studies of nuclei far from stability. One approach for the calculation of breakup reactions of exotic nuclei into two fragments is to consider inelastic excitations into the single particle continuum of the projectile. Alternatively one can also consider the transfer to the continuum of a system composed of the light fragment and the target. In this work we make a comparative study of the two approaches, underline the different inputs, and identify the advantages and disadvantages of each approach. Our test cases consist of the breakup of $^{11}$Be on a proton target at intermediate energies, and the breakup of $^8$B on $^{58}$Ni at energies around the Coulomb barrier. We find that, in practice the results obtained in both schemes are in semiquantitative agreement. We suggest a simple condition that can select between the two approaches.Comment: 10 pages, 12 figures. Replaced by accepted version. To appear in Nucl. Phys.

alpha-particle production in the scattering of 6He by 208Pb at energies around the Coulomb barrier

New experimental data from the scattering of 6He+208Pb at energies around and below the Coulomb barrier are presented. The yield of breakup products coming from projectile fragmentation is dominated by a strong group of $\alpha$ particles. The energy and angular distributions of this group have been analyzed and compared with theoretical calculations. This analysis indicates that the $\alpha$ particles emitted at backward angles in this reaction are mainly due to two-neutron transfer to weakly bound states of the final nucleus.Comment: 20 pages, 5 figures. Nuclear Physics A792 (2007) 2-1

Diquark condensation effects on hot quark star configurations

The equation of state for quark matter is derived for a nonlocal, chiral quark model within the mean field approximation.We investigate the effects of a variation of the formfactors of the interaction on the phase diagram of quark matter. Special emphasis is on the occurrence of a diquark condensate which signals a phase transition to color superconductivity and its effects on the equation of state under the condition of beta- equilibrium and charge neutrality. We calculate the quark star configurations by solving the Tolman- Oppenheimer- Volkoff equations and obtain for the transition from a hot, normal quark matter core of a protoneutron star to a cool diquark condensed one a release of binding energy of the order of Delta M c^2 ~ 10^{53} erg. We find that this energy could not serve as an engine for explosive phenomena since the phase transition is not first order. Contrary to naive expectations the mass defect increases when for a given temperature we neglect the possibility of diquark condensation.Comment: 24 pages, 2 tables, 8 figures, references added, figures and text improve

Before and after EEES spirit in biometrics for pharmacy

Biometría es una asignatura troncal de primer curso del grado de Farmacia. Últimamente, los profesores tratan de adaptarla al espíritu del EEES. El mayor esfuerzo se enfoca hacia el desarrollo de la capacidad de auto-crítica, auto-aprendizaje y de una evaluación adecuada. Algunos métodos tradicionales ya lo pretendían, como la provisión de resúmenes teóricos, la discusión de problemas matemáticos del ámbito farmacéutico dados de antemano o el uso de un paquete informático estadístico. Además, actualmente los alumnos tienen acceso a una página web de la asignatura con esos materiales junto con ejemplos resueltos, presentaciones, etc. La mayor novedad es un curso inicial para repasar conceptos básicos previos y el acceso a tests de autoevaluación a lo largo del curso. La evaluación consistía en un examen final y ahora de cuatro exámenes cortos, otro de las capacidades de uso del paquete estadístico y uno final. El estudio estadístico de las calificaciones desde 2003 hasta 2008 muestran que: 1. Los turnos de la mañana y la tarde son comparables. 2. Las calificaciones de junio y septiembre no son comparables. 3. Las calificaciones son siempre bajas. 4. Las calificaciones son similares para ambos estilos de enseñanza. Por tanto, debemos reflexionar acerca de los resultados. Estudiando lo obtenido tras una encuesta a alumnos y profesores, concluimos lo siguiente: es necesario una mejora en los conocimientos previos de los alumnos, animar a alumnos y profesores a romper con la antigua forma de aprender y la disminución del ratio de alumnos por clase.Biometrics is a mandatory subject in the first course of the Pharmacy degree. In the last few years, its professors try to adapt it to the EEES spirit. The biggest effort is focused on developing the self-criticisim, self-learning competences and a suitable evaluation method. Some of the traditional teaching methods already aimed that, such us providing theory summaries and discussions about mathematical problems within the pharmacy framework proposed in advanced and the use of a statistical package. Nowadays, besides that, the students have a subject web page with the summaries, problems, solved examples, slide presentations, etc. The biggest novelties are an initial course to review preliminary basic concepts and self-evaluation multiple-choice tests provided along the whole term. The evaluation changed from one final exam to four short ones, an exam of their skills at using the statistics package and a final exam.The statistical analysis of the final marks from the 2003 to 2008 shows that: 1. Morning and afternoon shifts are comparable. 2. June and September marks are not comparable. 3. Final marks are always low. 4. Final marks are similar for both teaching styles. Therefore, we should reflect on the results carefully. Having studied the data of a survey among professors and students, we come to the following conclusions: it is necessary to ask for higher student’s knowledge basis, to encourage them and professors to break the chains of old ways of learning and to ask for a decrease in the ratio of students per class.Este trabajo ha sido parcialmente apoyado por los proyectos MTM2007-63793 del Plan Nacional I+D+I, Ministerio de Ciencia e Innovación, y FQM-307 de la Consejería de Innovación de la Junta de Andalucía

Ising cubes with enhanced surface couplings

Using Monte Carlo techniques, Ising cubes with ferromagnetic nearest-neighbor interactions and enhanced couplings between surface spins are studied. In particular, at the surface transition, the corner magnetization shows non-universal, coupling-dependent critical behavior in the thermodynamic limit. Results on the critical exponent of the corner magnetization are compared to previous findings on two-dimensional Ising models with three intersecting defect lines.Comment: 4 pages, 2 figures included, submitted to Phys. Rev.

Elastic Scattering and Total Reaction Cross Section for the 6He + 27Al System

The elastic scattering of the radioactive halo nucleus 6He on 27Al target was measured at four energies close to the Coulomb barrier using the RIBRAS (Radioactive Ion Beams in Brazil) facility. The Sao Paulo Potential(SPP) was used and its diffuseness and imaginary strength were adjusted to fit the elastic scattering angular distributions. Reaction cross-sections were extracted from the optical model fits. The reduced reaction cross-sections of 6He on 27Al are similar to those for stable, weakly bound projectiles as {6,7}Li, 9Be and larger than stable, tightly bound projectile as 16O on 27Al.Comment: 7 pages, 1 table, 3 figure

Recent experimental results in sub- and near-barrier heavy ion fusion reactions

Recent advances obtained in the field of near and sub-barrier heavy-ion fusion reactions are reviewed. Emphasis is given to the results obtained in the last decade, and focus will be mainly on the experimental work performed concerning the influence of transfer channels on fusion cross sections and the hindrance phenomenon far below the barrier. Indeed, early data of sub-barrier fusion taught us that cross sections may strongly depend on the low-energy collective modes of the colliding nuclei, and, possibly, on couplings to transfer channels. The coupled-channels (CC) model has been quite successful in the interpretation of the experimental evidences. Fusion barrier distributions often yield the fingerprint of the relevant coupled channels. Recent results obtained by using radioactive beams are reported. At deep sub-barrier energies, the slope of the excitation function in a semi-logarithmic plot keeps increasing in many cases and standard CC calculations over-predict the cross sections. This was named a hindrance phenomenon, and its physical origin is still a matter of debate. Recent theoretical developments suggest that this effect, at least partially, may be a consequence of the Pauli exclusion principle. The hindrance may have far-reaching consequences in astrophysics where fusion of light systems determines stellar evolution during the carbon and oxygen burning stages, and yields important information for exotic reactions that take place in the inner crust of accreting neutron stars.Comment: 40 pages, 63 figures, review paper accepted for EPJ