2,728 research outputs found

    General behavior of the effective nucleon-nucleon interaction as a function of the relative velocity

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    We have studied volume integrals of the central part of optical potentials extracted from data analyses for a variety of light and heavy systems. The data-extracted integrals present a quite simple behavior as a function of the relative velocity between target and projectile. This behavior is system independent and, therefore, it reflects a feature of the effective nucleon-nucleon interaction itself. The overall results are in good agreement with the predictions of the São Paulo potential, which is a model for the nuclear interaction that so far has been employed mostly in analyses of heavy-ion reactions

    THE SANSEVERO CHAPEL, A THREE-DIMENSIONAL POINT OF VIEW

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    Abstract. In this article, the importance of the three-dimensional survey in architectural spaces will be studied, taking special relevance in the study of the perception of perspective, since three-dimensional space would not be understood from a two-dimensional representation of space. The project aims to develop a comparison between the representation systems based on the automatic acquisition of various data by different 3D survey techniques. In particular, the document reports the results of an analysis based on the Sansevero Chapel in Naples.</p

    Investigation of Coulomb dipole polarization effects on reactions involving exotic nuclei

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    We have analyzed elastic scattering angular distributions and total reaction cross sections of the exotic nuclei Li9,11 on Pb208, at energies below and above the Coulomb barrier. For this purpose, we have used an optical potential with no adjustable parameters, composed by the nuclear São Paulo potential, derived from the nonlocal nature of the interaction, and the Coulomb dipole polarization potential, derived from the semiclassical theory of Coulomb excitation. Within this formalism, we identified an unusual long-range absorption for the Li11+Pb208 system, which is dominated by the Coulomb interaction. We compare it to the absorption mechanisms observed for He6+Pb208 which, unlike those of Li11+Pb208, take place at small interacting distances, where both Coulomb and nuclear interactions are important. The proposed approach shows to be a fundamental basis to study reactions involving exotic nuclei

    Experimental simulation of simultaneous vision

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    Purpose. To present and validate a prototype of an optical instrument that allows experimental simulation of pure bifocal vision. To evaluate the influence of different power additions on image contrast and visual acuity. Methods. The instrument provides the eye with two superimposed images, aligned and with the same magnification, but with different defocus states. Subjects looking through the instrument are able to experience pure simultaneous vision, with adjustable refractive correction and addition power. The instrument is used to investigate the impact of the amount of addition of an ideal bifocal simultaneous vision correction, both on image contrast and on visual performance. The instrument is validated through computer simulations of the letter contrast and by equivalent optical experiments with an artificial eye (camera). Visual acuity (VA) was measured in four subjects (age: 34.3 ± 3.4 years; spherical error: -2.1 ± 2.7 diopters [D]) for low and high contrast letters and different amounts of addition. Results. The largest degradation in contrast and visual acuity (~25%) occurred for additions around ±2 D, while additions of ±4 D produced lower degradation (14%). Low additions (1-2 D) result in lower VA than high additions (3-4 D). Conclusions. A simultaneous vision instrument is an excellent tool to simulate bifocal vision and to gain understanding of multifocal solutions for presbyopia. Simultaneous vision induces a pattern of visual performance degradation, which is well predicted by the degradation found in image quality. Neural effects, claimed to be crucial in the patients' tolerance of simultaneous vision, can be therefore compared with pure optical effects. Copyright 2013 The Association for Research in Vision and Ophthalmology, Inc.Supported by Spanish Government Grant FIS2011-25637 and European Advanced Grant ERC-2011-AdG-294099 to SM.Peer Reviewe

    Insights into the room temperature magnetism of ZnO/Co3O4 mixtures

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    The origin of room temperature (RT) ferromagneticlike behavior in ZnO-based diluted magnetic semiconductors is still an unclear topic. The present work concentrates on the appearance of RT magnetic moments in just mixed ZnO/Co3O4 mixtures without thermal treatment. In this study, it is shown that the magnetism seems to be related to surface reduction of the Co3O4 nanoparticles, in which, an antiferromagnetic Co3O4 nanoparticle (core) is surrounded by a CoO-like shell. This singular superficial magnetism has also been found in other mixtures with semiconductors such as TiO2 and insulators such as Al2O3

    Estudio de la obesidad y del sobrepeso como factores de riesgo de la prevalencia y severidad del asma en niños de Valencia

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    [email protected]; [email protected]; [email protected]: La obesidad y el sobrepeso se han descrito como factores de riesgo asociados a la prevalencia y severidad del asma en niños y adolescentes. El objetivo del estudio ha sido el valorar el papel de la obesidad en el asma infantil. Ámbito de estudio y sujetos:Estudio realizado en niños y adolescentes entre 8 y 15 años, elegidos por un muestreo aleatorio tipo cluster entre los niños que estudiaban en 80 colegios, el cual representa el 30% de los colegios de la ciudad de Valencia. Material y métodos:El análisis de los datos se organizó en dos grupos, obesos (aquellos niños en un percentil superior al 85 del Índice de Masa Corporal (kg/m2), tomando como referencia la población española) y no obesos, cuando no cumplian esta condición. Se calcularon la prevalencia de los diferentes parámetros con un intervalo de confianza al 95%, y el riesgo relativo (RR) de los síntomas compatibles con asma entre niños obesos comparándolos con los no obesos. Resultados: No se obtuvo un riesgo relativo significativo para la obesidad con respecto al asma en aquellos niños por encima del percentil 85. Por otra parte, un incremento en el riesgo en relación con la severidad del asma se observó con la obesidad, principalmente en el percentil 85 (RR = 1,51 de sufrir entre 4-12 ataques de pitos y RR = 1,86 de sufrir más de 12 ataques en niños obesos frente a los no obesos) Conclusiónes: En este estudio, no identificamos un riesgo más alto de asma entre niños obesos frente a los no obesos, aunque encontramos que hubiera un riesgo más alto de severidad de síntomas asmáticos. En relación con la severidad del asma, observamos un riesgo más alto de ataques de pitos y sibilancias entre los niños obesos en los percentiles 85 y 95 del Indice de Masa Corporal.Background: Obesity and overweight have been described as factors associated with asthma. Our aim was to evaluate the role obesity plays on asthma in children. Scope and subjects: A study carried out on children and teenagers between 8 and 15 years of age, chosen for a cluster-type random sampling from children who studied in 80 schools, which represents 30% of the schools in the city of Valencia. Material and Methods: The analysed data was organized into two groups, obese (from the Body Mass Index (Kg/m2)), showing children with a percentile over 85% of the measuring reference for the Spanish population) and non obese, when they did not fulfil this condition. The prevalence of the different parameters studied was calculated by an Interval of Confidence of 95%. The risk was calculated (Relative Risk) from those symptoms compatible with asthma among obese children compared to non obese children. Results: No significant relative risk (RR) was seen for obesity with regards to asthma in those percentiles of obesity over 85. Otherwise, an increase in the relative risk (RR) regarding the severity of asthma was seen in relation to obesity, mainly in the 85th percentile (RR = 1.51 of suffering between 4-12 wheezing attacks and RR = 1.86 of suffering more than 12 attacks in obese children as opposed to non obese children). Conclusions: In this study, we did not identify a higher risk of asthma among obese children than among non obese children, although we did find there was a higher risk of severity of asthmatic symptoms. As far as the severity of the asthma is concerned, we saw a higher risk of wheezing and whistling attacks among obese children with the 85th and the 95th percentiles according to the Body Mass [email protected]; [email protected]; [email protected]

    Elastic scattering, inelastic excitation, and 1 n pick-up transfer cross sections for 10 B + 120 Sn at energies near the Coulomb barrier

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    The 10 B + 120 Sn reaction has been systematically studied at laboratory energies around the Coulomb barrier: E LAB = 31.5 , 33.5, 35.0, and 37.5 MeV. Cross sections for the elastic scattering and some reaction processes have been measured: excitation to the 1 + state of 10 B ; excitation to the 2 + and 3 − states of 120 Sn ; and the one-neutron pick-up transfer 120 Sn ( 10 B , 11 B ) 119 Sn . Coupled reaction channel (CRC) calculations have been performed in the context of the double-folding São Paulo potential. The theoretical calculations result in a good overall description of the experimental angular distributions. The effect on the theoretical elastic-scattering angular distributions of couplings to the inelastic and transfer states (through the CRC calculations) and to the continuum states (through continuum-discretized coupled-channels calculations) has been investigated.Instituto Nacional de Ciência e Tecnologia–Física Nuclear e Aplicações (INCT-FNA) 464898/2014-5Ministerio de Economía y Competitividad de España y el Fondo Europeo de Desarrollo Regional (FEDER) FIS2014-51941-P,Junta de Andalucía. FQM-160Programa de investigación e innovación de la Unión Europea Horizonte 2020. 65400

    Systematical study of the optical potential for systems like A+ 58Ni from sub-barrier data analyses

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    Elastic scattering differential cross sections were measured for the 28Si158Ni system at sub-barrier energies. The corresponding nuclear potential was compared with earlier results of systems like A158Ni. The present data also allowed the determination of the 28Si nuclear density through an unfolding method. The experimentally extracted 28Si density values are compared with those previously obtained for the 4,6He, 12C, 16,18O nuclei. We present a critical discussion of the absolute precision obtained for the density parameters extracted from the data analyses

    Interaction of 8 He with 208Pb at near-barrier energies: 4 He and 6 He production

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    Spanish Ministry of Economy and Competitiveness-FPA-2010-22131-CO2-01 (FINURA) y FPA2013-47327-C2-1-RMinistry of Science and Higher Education of Poland-N202 033637National Science Centre of Poland-2013/08/M/ST2/00257 (LEA-COPIGAL) y 2014/14/M/ST2/00738 (COPIN-INFN Collaboration)European Science Foundation-EUI2009-04163432 (EUROGENESIS
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