Excited states of beryllium atom from explicitly correlated wave functions

A study of the first excited states of beryllium atom starting from explicitly correlated wave functions is carried out. Several properties are obtained and discussed focusing on the analysis of the Hund's rules in terms of the single--particle and electron pair intracule and extracule densities. A systematic study of the differences on the electronic distributions of the singlet and triplet states is carried out. The trial wave function used to describe the different bound states consists of a generalized Jastrow-type correlation factor times a configuration interaction model wave function. This model wave function has been fixed by using a generalization of the optimized effective potential method to deal with multiconfiguration wave functions. The optimization of the wave function and the calculation of the different quantities is carried out by means of the Variational Monte Carlo method.Comment: 28 pages, 6 figure

ANAIS-0: Feasibility study for a 250 kg Nal(Tl) dark matter search experiment at the Canfranc Undreground Laboratory

Este trabajo ha consistido en un estudio de viabilidad del experimento ANAIS (Annual modulation with NaI(Tl) Scintillators) cuyo objetivo es la detección directa de materia oscura con 250 kg de NaI(Tl) en el Laboratorio Subterráneo de Canfranc (LSC). El experimento ANAIS tratará de corroborar la señal positiva obtenida por el experimento DAMA-LIBRA utilizando el mismo material blanco y técnica de detección. La mayor parte de este estudio se ha llevado a cabo con el módulo ANAIS-0, fabricado con un cristal de 9.6 kg de NaI(Tl) y encapsulado en la Universidad de Zaragoza, que ha operado en diferentes configuraciones experimentales en el LSC. La versatilidad de este prototipo ha posibilitado el estudio del sistema de recogida de luz, ha proporcionado datos en diferentes condiciones experimentales que han permitido desarrollar un modelo del fondo radiactivo muy satisfactorio y se han diseñado protocolos de análisis de datos para el filtrado de poblaciones anómalas de eventos, no atribuibles al centelleo en el cristal de NaI. En la última etapa de este trabajo, dos cristales ultrapuros de NaI(Tl) fabricados con polvo especialmente seleccionado por su bajo contenido en potasio, fueron instalados en el LSC (ANAIS-25) y están tomando datos en la actualidad. De forma preliminar, los distintos protocolos de análisis de datos desarrollados y optimizados con ANAIS-0 se han aplicado a los datos de ANAIS-25 para obtener resultados preliminares muy favorables sobre la calidad óptica y de radiopureza de los cristales

Information Retrieval with Finnish Case Law Embeddings

In this work, five text vectorisation models' capability in embedding Finnish case law texts to vector space for inter-textual similarity computation is studied. The embeddings and their computed similarities are used to create a Finnish case law retrieval system that allows effective querying with full documents. A working web application is presented as a part of the work. The case law data for the work is provided by the Finnish Ministry of Justice, and the studied models are: TF-IDF, LDA, Word2Vec, Doc2Vec and Doc2vecC

IMPLICATIONS OF OPEN EDUCATIONAL RESOURCES FOR YOUR MEMORY OF LINKS

Open contents also open the door for acquiring a large variety and quantity of new knowledge. They are always available for us, and once they are located and selected, we only need to wait as long as necessary to have enough time to learn them. Storing contents on very different ICT devices may contribute to freeze the overload of our memory, but some studies affirm that a smaller cognitive effort is made when we know the contents are ready out there, in the Web. This article is focused into the implications of incorporating different digital open resources in your ‗Memory of Links‘ (MoL). This concept, the MoL, represents the space of memory which needs to be allocated in the brain for storing those links. The seeking and selection processes, the memorization and storage of links, the ability to remember some notions about the stored information and the need of organization of those linked resources in external devices vary according to the different individuals. This fact has been checked through a study carried out with 58 students who were surveyed and interviewed in order to obtain information about the way they filled their MoL. The individuals showed distinct behaviors in respect of the number and type of the stored links, storage devices, structuration of information, link management tools, etc

Note on an elementary inequality and its application to the regularity of p-harmonic functions

Peer reviewe

Quadratic diffusion Monte Carlo and pure estimators for atoms

The implementation and reliability of a quadratic diffusion Monte Carlo method for the study of ground-state properties of atoms are discussed. We show in the simple yet non-trivial calculation of the binding energy of the Li atom that the method presented is effectively second-order in the time step. The fulfilment of the expected quadratic behavior relies on some basic requirements of the trial wave function used for importance sampling, in the context of the fixed-node approximation. Expectation values of radial operators are calculated by means of a pure estimation based on the forward walking methodology. It is shown that accurate results without extrapolation errors can be obtained with a pure algorithm that can be easily implemented in any previous diffusion Monte Carlo program.Comment: RevTex, 20 pages, 3 figures, accepted in J. Chem. Phy

Background evaluation of the ANAIS dark matter experiment in different configurations: towards a final design

INTRODUCCIÓN Y MOTIVACIÓN DE LA TESIS Existen numerosas evidencias de que la mayor parte de la materia del Universo es "oscura", y diversos experimentos se han dedicado a su detección directa con diferentes blancos y técnicas. Hasta la fecha, sólo el experimento DAMA/LIBRA, en el Laboratorio Nacional del Gran Sasso, Italia, ha reivindicado una señal positiva de modulación anual como la que se espera que produzcan las partículas de materia oscura que constituyen el halo de nuestra galaxia, que no es compatible ni con fondos convencionales ni con los variados efectos sistemáticos propuestos. El proyecto ANAIS, desarrollado por la Universidad de Zaragoza, tiene como objetivo la confirmación de la señal positiva de DAMA/LIBRA usando el mismo blanco y técnica de detección. DESARROLLO TEÓRICO ANAIS-112 usará 112.5 kg de NaI(Tl) ultrapuro en nueve detectores. Se ha llevado a cabo un extenso trabajo para caracterizar y cuantificar las contribuciones al fondo radiactivo de los diferentes prototipos considerados. En este trabajo se presentan los resultados de los cuatro primeros detectores fabricados por la compañía Alpha Spectra (D0-D3), basados en medidas en el Laboratorio Subterráneo de Canfranc y simulaciones por Monte Carlo. CONCLUSIÓN Los modelos de fondo construidos para los detectores D0, D1 y D2, así como los resultados preliminares de D3, describen satisfactoriamente los datos medidos en diferentes condiciones de análisis. La inclusión de algunas hipótesis adicionales, como la presencia de isótopos cosmogénicos que no pueden ser cuantificados directamente o la contaminación parcial de 210Pb en la superficie, mejoran significativamente la concordancia del modelo con los datos reales. El detector D2 presenta el mejor fondo medido hasta la fecha, pero se espera mejorarlo todavía más en ANAIS-112 gracias al incremento del poder de rechazo en un montaje multimodular, que permita eliminar coincidencias, y un mayor control de la radiopureza de los módulos restantes. Además, se han evaluado las perspectivas de fondo para el experimento completo, teniendo en cuenta el diseño planeado para ANAIS-112, así como otros escenarios hipotéticos, como una matriz de detectores de NaI(Tl) correspondiente a 250 kg, o el uso de un veto de centelleo líquido. Finalmente, la sensibilidad de ANAIS en la búsqueda de la modulación anual de la señal de materia oscura ha sido evaluada en diferentes configuraciones experimentales y condiciones de fondo, confirmando que ANAIS-112 con el fondo ya obtenido en D2 podrá explorar la señal de DAMA/LIBRA. BIBLIOGRAFÍA - R. Bernabei, P. Belli, F. Cappella et al., Final model independent results of DAMA/LIBRA-phase 1 and perspectives of phase 2, Phys. Part. Nuclei 46, 138 (2015). - M. Martínez, Diseño de un prototipo para un experimento de detección directa de materia oscura mediante modulación anual con centelleadores de ioduro de sodio, Tesis Doctoral, Universidad de Zaragoza, 2006. - C. Cuesta et al., Analysis of the 40K contamination in NaI(Tl) crystals from different providers, Int. J. Mod. Phys. A 29, 1443010 (2014). - C. Cuesta et al., Bulk NaI(Tl) scintillation low energy events selection with the ANAIS-0 module, Eur. Phys. J. C 74, 3150 (2014). - C. Cuesta, ANAIS-0: Feasibility study for a 250 kg NaI(Tl) dark matter search experiment at the Canfranc Underground Laboratory, Tesis Doctoral, Universidad de Zaragoza (2013). - M.A. Oliván, Design, scale-up and characterization of the data acquisition system for the ANAIS dark matter experiment, Tesis Doctoral, Universidad de Zaragoza, (2016). - J. Amaré et al., Assessment of backgrounds of the ANAIS experiment for dark matter direct detection, Eur. Phys. J. C 76, 429 (2016)

A roadmap to cope with common problems in E-learning research designs

E-learning research is plenty of difficulties, as also research in education is. Usually, the high number of features involved in e-learning processes complicates and masks the identification and isolation of the factors which cause the expected benefits, when they exist. At the same time, a bunch of threats are ready to weaken the validity of the research, for example, disregard of previous research, use of small samples, absence of randomization in the assignment to groups, ineffective designs, lack of objectivity in the measuring process, poor descriptions of the research in publications (which implies few possibilities of replication), wrong statistical procedures, inappropriate inference of results, etc. All of these obstacles accumulate and are carried along the whole research, resulting in low quality studies or irrelevant ones. This theoretical paper suggests a roadmap in order to face the most common problems in e-learning research. The roadmap informs about some cautions which must be considered at each stage of the research and recommendations to increase the validity and reproducibility of results. The roadmap and conclusions included in this paper have been obtained from our experience in educational and e-learning research, also from our long path as reviewers in key journals of these fields, and from readings of significant research handbooks. This is not a strict guide but a set of milestones on which it is necessary to stop and reflect