Study of the optical behavior of skins using Monte Carlo techniques

Uno de los principales retos en óptica biomédica y en biofotónica es la simulación de la propagación de la luz en los tejidos biológicos. El método de Monte Carlo es la aproximación más empleada, y se puede afirmar que constituye un estándar por su flexibilidad y fiabilidad en modelar la geometría de un tejido heterogéneo. Este trabajo muestra cómo analizar el comportamiento óptico de la piel y cómo algunas de las deducciones extraídas de este análisis pueden aportar información para el diagnóstico y el tratamiento de pieles. Se han aplicado las propiedades ópticas de pieles sanas de diferentes razas y, como alteración posible en la piel, se ha estudiado la presencia del basalioma. Los resultados nos ofrecen un método para distinguir entre piel «sana» y piel «enferma», lo que podría facilitar un procedimiento de identificación de pieles cancerígenas. Del estudio de los distintos tipos de pieles sanas se desprende, además, un ejemplo de aplicación inmediata que se beneficia del conocimiento adquirido por los valores obtenidos (fotodepilación). En este trabajo se presentan los resultados más significativos de los programas de simulación basados en técnicas de Monte Carlo, que permiten estudiar el comportamiento de la piel frente a una radiación óptica. La aproximación a la trayectoria que sigue la luz en su interacción con el tejido se obtiene a partir de las propiedades ópticas conocidas a priori. Se realiza una aproximación general al tema, identificando los principales problemas que se plantean en este tipo de estudios y se emplea un programa comercial.In both biomedical optics and biophotonics, one of the main challengers is the simulation of light spread in biological tissues. The approximation which is most used is Monte Carlos method; it is a standard because of its flexibility and its reliability modeling heterogeneous tissues. This paper shows how to analyse the optical behaviour of the skin, and how some of the deductions drawn from this analysis can add information for the diagnosis and treatment of skins. The optic qualities of healthy skins from different races have been applied; and as a possible alteration in the skin, basalioma presence has been studied. The results provide us with a method to distinguish between “healthy” and “ill” skin, which could make the procedure to identify cancer skins easier. From the study of the different healthy skins an example of immediate application also appears which benefits from the knowledge acquired from the values obtained (photodepilation). In this work the most valued results of the simulation programs based in Monte Carlos technics are presented, which allow studying the skins behaviour facing an optical radiation; the approximation to the light trajectory interacting with the tissues is obtained from the optic qualities known before. First of all, a general approach to the theme is carried out, identifying the main problems that appear in this kind of studies and a commercial programme is used.Peer Reviewe

Classical analogs of generalized purities, entropies, and logarithmic negativity

It has recently been proposed classical analogs of the purity, linear quantum entropy, and von Neumann entropy for classical integrable systems, when the corresponding quantum system is in a Gaussian state. We generalized these results by providing classical analogs of the generalized purities, Bastiaans-Tsallis entropies, R\'enyi entropies, and logarithmic negativity for classical integrable systems. These classical analogs are entirely characterized by the classical covariance matrix. We compute these classical analogs exactly in the cases of linearly coupled harmonic oscillators, a generalized harmonic oscillator chain, and a one-dimensional circular lattice of oscillators. In all of these systems, the classical analogs reproduce the results of their quantum counterparts whenever the system is in a Gaussian state. In this context, our results show that quantum information of Gaussian states can be reproduced by classical information.Comment: 17 pages. 9 figure

The Digital Competence of Pre-Service Educators: The Influence of Personal Variables

[EN] Currently, 21st century students need competences that enable them to adapt to a new type of individual information and individual knowledge relationship, and, therefore, the education system should contemplate new ways for learners to develop in accordance with this so-called information and knowledge society. One of special importance is so-called digital competency. This article presents the results of a research study to determine the influence that the variables of gender, age, and academic degree have on the acquisition of digital competence by pre-service educators, with a sample of 370 students from different education degrees from the University of Salamanca (Spain). A quantitative methodology was used, employing a non-experimental method and the electronic survey technique to collect information on the dimensions of knowledge, as well as the management of and attitude towards information and communication technologies (ICTs). Data were analyzed inferentially from a comparison of means using nonparametric tests. This analysis was completed with the incorporation of Receiver Operating Characteristic (ROC) curves, which allowed us to graphically verify the differences between the subsamples and thus compare the different groups in relation to the proposed dimensions. The main conclusion was that the three variables studied can be considered as influential, though not determinant, in the acquisition of digital competency

The Digital Competence of Pre-Service Educators: The Influence of Personal Variables

[EN]Currently, 21st century students need competences that enable them to adapt to a new type of individual information and individual knowledge relationship, and, therefore, the education system should contemplate new ways for learners to develop in accordance with this so-called information and knowledge society. One of special importance is so-called digital competency. This article presents the results of a research study to determine the influence that the variables of gender, age, and academic degree have on the acquisition of digital competence by pre-service educators, with a sample of 370 students from different education degrees from the University of Salamanca (Spain). A quantitative methodology was used, employing a non-experimental method and the electronic survey technique to collect information on the dimensions of knowledge, as well as the management of and attitude towards information and communication technologies (ICTs). Data were analyzed inferentially from a comparison of means using nonparametric tests. This analysis was completed with the incorporation of Receiver Operating Characteristic (ROC) curves, which allowed us to graphically verify the differences between the subsamples and thus compare the different groups in relation to the proposed dimensions. The main conclusion was that the three variables studied can be considered as influential, though not determinant, in the acquisition of digital competency

Relativistic two-body currents for one-nucleon knockout in electron-nucleus scattering

We present a detailed study of the contribution from two-body currents to the one-nucleon knockout process induced by electromagnetic interaction. The framework is a relativistic mean-field model (RMF) in which bound and scattering nucleons are consistently described as solutions of Dirac equation with potentials. We show results obtained with the most general expression of the two-body operator, in which the intermediate nucleons are described by relativistic mean-field bound states; then, we propose two approximations consisting in describing the intermediate states as nucleons in a relativistic Fermi gas, preserving the complexity and consistency in the initial and final states. These approximations simplify the calculations considerably, allowing us to provide outcomes in a reasonable computational time. The results obtained under these approximations are validated by comparing with those from the full model. Additionally, the theoretical predictions are compared with experimental data of the longitudinal and transverse responses of carbon 12. The agreement with data is outstanding for the longitudinal response, where the contribution from the two-body operator is negligible. In the transverse sector, the two-body current increases the response from 30 to 15%, depending on the approximations and kinematics, in general, improving the agreement with data.Comment: 11 pages, 5 figure

Digital competence of early childhood education teachers: attitude, knowledge and use of ICT

[EN] The main objective of the research described here was to learn how young learners self-evaluate their digital competence. A nonexperimental and descriptive quantitative methodology was employed, an electronic survey being used to collect the data. Among the main results, we can highlight that these learners selfevaluate their attitude towards Information and Communication Technologies (ICT) as favourable, their handling of them as moderate and their knowledge of them as scarce. It became clear that they do not have a level of digital competence suitable for being called ‘digital natives’, nor sufficient ability to use ICT in their academic life or in their professional future

Hexacoordinated Oligosilanes from a Hexacoordinated Silicon(IV) Complex Containing an O,N,N,O Salen-type and Thiocyanato-N Ligands

8 páginas, 4 figuras, 3 esquemas, 1 tabla.Two new neutral hexacoordinated silicon complexes with SiN4O2 (6) and SiN3O2C (7) coordinating frameworks were synthesized by reaction of the O,N,N,O-donor salen-type ligand 1,2-bis[[(2-hydroxy-4-methoxyphenyl)(phenyl)methylene]amino]ethane (H2salen*) with Si(NCS)4 and HMeSi(NCS)2, respectively. The complexes 6 [Si(salen*)(NCS)2] and 7 [Si(salen*)Me(NCS)] were studied in the solid-state by 29Si and 15N CP/MAS NMR and in solution by 1H, 13C, and 29Si insensitive nuclei enhanced by polarization transfer (INEPT) NMR, UV/vis and FT-IR spectroscopy. Elemental analysis and single-crystal X-ray diffraction analysis were used to confirm the composition and structure for compounds 6 and 7. Both complexes contain the dianionic salen-type ligand coordinated in an equatorial fashion to the silicon center, while the axial positions are occupied by two thiocyanato-N ligands for 6 and one thiocyanato-N and one methyl ligand for 7. Complex 6, which contains two Si−NCS functional groups, was used as monomer to produce a mixture of linear oligosilanes with a hexacoordinated silicon backbone (formulated SCN-[Si(salen*)]n-NCS, n = 2−8) 8, via a Wurtz-type coupling reaction. Oligomers 8 were identified by solid-state 29Si cross polarization-magic angle spinning NMR and solution 1H and 29Si NMR spectroscopy, matrix assisted laser desorption ionization-time of flight (MALDI-TOF), gel-permeation chromatography (GPC), FT-IR, UV/vis spectroscopy and thermogravimetric analysis (TGA). Conclusive evidence of the oligomeric nature of 8 was provided by MALDI-TOF spectrometry and was supported by quantitative solution 29Si NMR and GPC studies.Financial support for this work was provided by the Mexican Department of Public Education (PROMEP-SEP). G.G.G. thanks the Mexican National Council for Science and Technology (Conacyt) for a PhD scholarship.Peer reviewe

There are no multiply-perfect Fibonacci numbers

Here, we show that no Fibonacci number (larger than 1) divides the sum of its divisors

Insights into the room temperature magnetism of ZnO/Co3O4 mixtures

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