Constructive updating/downdating of oblique projectors: a generalization of the Gram-Schmidt process

A generalization of the Gram-Schmidt procedure is achieved by providing equations for updating and downdating oblique projectors. The work is motivated by the problem of adaptive signal representation outside the orthogonal basis setting. The proposed techniques are shown to be relevant to the problem of discriminating signals produced by different phenomena when the order of the signal model needs to be adjusted.Comment: As it will appear in Journal of Physics A: Mathematical and Theoretical (2007

Measurements design and phenomena discrimination

The construction of measurements suitable for discriminating signal components produced by phenomena of different types is considered. The required measurements should be capable of cancelling out those signal components which are to be ignored when focusing on a phenomenon of interest. Under the hypothesis that the subspaces hosting the signal components produced by each phenomenon are complementary, their discrimination is accomplished by measurements giving rise to the appropriate oblique projector operator. The subspace onto which the operator should project is selected by nonlinear techniques in line with adaptive pursuit strategies

On the truncation of the harmonic oscillator wavepacket

We present an interesting result regarding the implication of truncating the wavepacket of the harmonic oscillator. We show that disregarding the non-significant tails of a function which is the superposition of eigenfunctions of the harmonic oscillator has a remarkable consequence: namely, there exist infinitely many different superpositions giving rise to the same function on the interval. Uniqueness, in the case of a wavepacket, is restored by a postulate of quantum mechanics

Aproximación a los problemas de aprendizaje de la estructura y formación del suelo en el alumnado de 12 a 17 años

In a longitudinal study, carried out with 12- 17 year old students, to know learning obstacles and their evolution through schooling years, on the scientific concept of soil, we have found important data of learning problems on these topics, showing the established inefficiency of transmission of scientific knowledge to conceptual change. Lastly, we point out some implications for the teaching and significative learning of these concepts

Stabilized Schemes for the Hydrostatic Stokes Equations

Some new stable finite element (FE) schemes are presented for the hydrostatic Stokes system or primitive equations of the ocean. It is known that the stability of the mixed formulation ap- proximation for primitive equations requires the well-known Ladyzhenskaya–Babuˇska–Brezzi condi- tion related to the Stokes problem and an extra inf-sup condition relating the pressure and the vertical velocity. The main goal of this paper is to avoid this extra condition by adding a residual stabilizing term to the vertical momentum equation. Then, the stability for Stokes-stable FE combinations is extended to the primitive equations and some error estimates are provided using Taylor–Hood P2 –P1 or miniele- ment (P1 +bubble)–P1 FE approximations, showing the optimal convergence rate in the P2 –P1 case. These results are also extended to the anisotropic (nonhydrostatic) problem. On the other hand, by adding another residual term to the continuity equation, a better approximation of the vertical derivative of pressure is obtained. In this case, stability and error estimates including this better approximation are deduced, where optimal convergence rate is deduced in the (P 1 +bubble)–P1 case. Finally, some numerical experiments are presented supporting previous results

Assortative human pair-bonding for partner ancestry and allelic variation of the dopamine receptor D4 (DRD4) gene

The 7R allele of the dopamine receptor D4 gene has been associated with attention-deficit hyperactivity disorder and risk taking. On the cross-population scale, 7R allele frequencies have been shown to be higher in populations with more of a history of long-term migrations. It has also been shown that the 7R allele is associated with individuals having multiple-ancestries. Here we conduct a replication of this latter finding with two independent samples. Measures of subjects’ ancestry are used to examine past reproductive bonds. The individuals’ history of inter-racial/ancestral dating and their feelings about this are also assessed. Tentative support for an association between multiple ancestries and the 7R allele were found. These results are dependent upon the method of questioning subjects about their ancestries. Inter-racial dating and feelings about inter-racial pairing were not related to the presence of the 7R allele. This might be accounted for by secular trends that might have substantively altered the decision-making process employed when considering relationships with individuals from different groups. This study provides continued support for the 7R allele playing a role in migration and/or mate choice patterns. However, replications and extensions of this study are needed and must carefully consider how ancestry/race is assessed

On the Complexity of tt-Closeness Anonymization and Related Problems

An important issue in releasing individual data is to protect the sensitive information from being leaked and maliciously utilized. Famous privacy preserving principles that aim to ensure both data privacy and data integrity, such as $k$-anonymity and $l$-diversity, have been extensively studied both theoretically and empirically. Nonetheless, these widely-adopted principles are still insufficient to prevent attribute disclosure if the attacker has partial knowledge about the overall sensitive data distribution. The $t$-closeness principle has been proposed to fix this, which also has the benefit of supporting numerical sensitive attributes. However, in contrast to $k$-anonymity and $l$-diversity, the theoretical aspect of $t$-closeness has not been well investigated. We initiate the first systematic theoretical study on the $t$-closeness principle under the commonly-used attribute suppression model. We prove that for every constant $t$ such that $0\leq t<1$, it is NP-hard to find an optimal $t$-closeness generalization of a given table. The proof consists of several reductions each of which works for different values of $t$, which together cover the full range. To complement this negative result, we also provide exact and fixed-parameter algorithms. Finally, we answer some open questions regarding the complexity of $k$-anonymity and $l$-diversity left in the literature.Comment: An extended abstract to appear in DASFAA 201

Vitamina C : una estrategia didáctica polifuncional

El presente trabajo tiene como objetivo contextualizar contenidos curriculares de química: incursionando en el área de bioquímica, como elementos básicos de la formación en química del estudiante; proporcionando información general sobre las propiedades de la vitamina C que permitan al estudiante, como ciudadano, tener libertad de elección frente a la vasta publicidad que se ofrece, entre otros, en los medios masivos de comunicación; aplicando su cultura científica a situaciones de la vida cotidiana y, por lo tanto, valorando la importancia de la educación científica para poder ser capaz de conocer mejor lo que consume y poder opinar en forma crítica sobre ello. Se presentan técnicas sencillas para investigar la presencia de vitamina C en alimentos de uso común. Se discuten distintas estrategias de presentación y tratamiento del tema en los distintos niveles escolares con objetivos diferentes y se analizan cambios en la metodología de trabajo en el aula. Este trabajo fue presentado bajo la modalidad de taller en el XV Congreso Nacional e Internacional de Profesores de Química y los resultados y conclusiones a las que se arribaron fueron ampliamente satisfactorias, ya que permitieron una revalorización de la tarea educativa buscando un currículo más abierto donde el estudiante se sienta partícipe de su proceso de aprendizaje y encuentre contenidos científicos útiles para su vida.This paper attempts to contextualise chemistry curricula contents, entering the field of biochemistry, as basic elements for the formation of chemistry in the student by providing general information on the properties of C vitamin that allows the student, as a citizen, the freedom to choose in front of the huge publicity offered to them, among others, by the mass media. They can apply their scientific culture to everyday life, thus assessing how important scientific education is to be able to better know what is consumed and give a critical opinion. We present simple techniques to find C vitamin in commonly used food. We discuss different strategies to present and deal with this subject at different school levels with different aims, and we analyse the changes in the classroom working methodology. This paper was presented as a workshop in the 15th National and International Congress of Chemistry Professors and its results and conclusion were highly satisfactory, as they allowed revaluing the educational task aiming at a more open curriculum where the student feels part of his learning process and finds scientific contents useful in his everyday life

Metodología para seleccionar tecnologías Web 2.0 para la docencia

Actualmente existe un gran auge en el uso y difusión de las herramientas Web 2.0 tanto en el contexto profesional como en el personal. Su aplicación al ámbito de la docencia, tal y como sugieren algunos estudios, puede tener numerosas ventajas. Sin embargo, el abanico de herramientas Web 2.0 es muy amplio y por tanto sería de utilidad disponer de una metodología que pudiera guiar al docente a la hora de elegir la tecnología más adecuada a su proceso de enseñanza-aprendizaje según los objetivos perseguidos, así como en su implantación y posterior evaluación de los resultados alcanzados. En este artículo, se presenta una metodología de ayuda a los docentes de cualquier área de conocimiento para la selección e implantación de la tecnología Web 2.0 que más se adapte a un determinado proceso de enseñanza-aprendizaje en base a criterios docentes y técnicos. Esta metodología es el resultado de un proyecto de mejora e innovación educativa en el cual se han llevado a cabo diversas experiencias docentes sobre la aplicación de herramientas Web 2.0 en asignaturas de distintas titulaciones universitarias.SUMMARY -- The use and dissemination of Web 2.0 tools in professional and personal context is becoming more popular every day. Its application to teaching, as it is suggested by some studies, may have numerous advantages. However, the range of Web 2.0 tools is very broad and it would therefore be useful to have a methodology that guide the teacher in choosing the most appropriate technology to their teaching-learning process, taking into account some final objectives, as well as implementing and evaluating the achieved results. This paper presents a methodology to assist teachers from any area of knowledge in the selection of the Web 2.0 technology that best suits a particular teaching-learning process. This selection is based on some educational and technical criteria. The presented methodology is the result of an educational innovation and improvement project in which various teaching experiences based on the use of Web 2.0 tools have been carried out in different subjects of science degrees.Peer Reviewe