Dressing cosets revisited

We present an alternative algebraic derivation of the dual pair of nonlinear $\sigma$-models based on the 'dressing cosets' extension of the Poisson-Lie $T$-duality \cite{KS1}. Then we generalize the result to dual pairs of Lagrangians not considered in \cite{KS1}. Our generalization turns out to incorporate the dualisable models constructed by Sfetsos in \cite{Sfet1}.Comment: 24 page

Smooth Non-Abelian Bosonization

We present an extension of ``smooth bosonization'' to the non-Abelian case. We construct an enlarged theory containing both bosonic and fermionic fields which exhibits a local chiral gauge symmetry. A gauge fixing function depending on one real parameter allows us to interpolate smoothly between a purely fermionic and a purely bosonic representation. The procedure is, in the special case of bosonization, complementary to the approach based on duality.Comment: LaTeX, 13 pages, CERN--TH-7347/9

Chirp mitigation of plasma-accelerated beams using a modulated plasma density

Plasma-based accelerators offer the possibility to drive future compact light sources and high-energy physics applications. Achieving good beam quality, especially a small beam energy spread, is still one of the major challenges. For stable transport, the beam is located in the focusing region of the wakefield which covers only the slope of the accelerating field. This, however, imprints a longitudinal energy correlation (chirp) along the bunch. Here, we propose an alternating focusing scheme in the plasma to mitigate the development of this chirp and thus maintain a small energy spread

A Problem with Non-Abelian Duality

We investigate duality transformations in a class of backgrounds with non-Abelian isometries, i.e. Bianchi-type (homogeneous) cosmologies in arbitrary dimensions. Simple duality transformations for the metric and the antisymmetric tensor field, generalizing those known from the Abelian isometry (Bianchi I) case, are obtained using either a Lagrangian or a Hamiltonian approach. Applying these prescriptions to a specific conformally invariant \s-model, we show that no dilaton transformation leads to a new conformal background. Some possible ways out of the problem are suggested.Comment: 14pages, CERN-TH.6960/93 ROM2F/93/24 (One reference and one paragraph added

Hla b27 y espondiolitis anquilosante: estudio de asociación en la población colombiana

Demostrar la asociación del gen HLA B27 con la espondilitis anquilosante (EA) a través de un estudio de casos y controles en la población colombiana

Nivel de sesgos cognitivos de representatividad y confirmación en estudiantes de Psicología de tres universidades del Bío-Bío

Cognitive biases are unreasonable ways of making decisions, often in a one-sided way. The objective of this research was to describe the level of representativeness and confirmation biases in Chilean psychology students, in order to know how this phenomenon occurs. The participants were 198 psychology students from three universities in southern Chile. The instrument was based on two cognitive tasks derived from Kanheman and Tversky. The data were analyzed through descriptive statistics and mean differences. The results indicate a high level of biases in the groups of students, in the two tasks evaluated; the representativeness bias presents differences among universities only in sub-task 1, as well as in task 2, related to confirmation bias. Likewise, there are differences in representation bias according to age and sex. The need to strengthen reasoning skills in the initial training of future psychologists, in order to improve skills related to decision making in the professional field is concluded.Los sesgos cognitivos son formas no razonadas de tomar decisiones, a menudo de manera parcializada. El objetivo de esta investigación fue describir el nivel de sesgos de representatividad y confirmación en estudiantes de psicología chilenos, para conocer cómo se presenta este fenómeno. Los participantes fueron 198 estudiantes de psicología, de tres universidades del sur de Chile. El instrumento se basó en dos tareas cognitivas derivadas de Kanheman y Tversky; se analizaron los datos con estadística descriptiva y diferencias de medias. Los resultados indican alto nivel de sesgos en los grupos de estudiantes, en las dos tareas evaluadas; el sesgo de representatividad presenta diferencias entre universidades, solo en la subtarea 1, así como en la tarea 2, relacionada con sesgo de confirmación; así mismo se observan diferencias en sesgo de representación según edad y sexo. Se concluye la necesidad de fortalecer habilidades de razonamiento en la formación inicial de los futuros psicólogos y psicólogas, con la finalidad de mejorar las habilidades relacionadas con la toma de decisiones en el campo profesional

Use of data imputation tools to reconstruct incomplete air quality datasets:a case-study in Temuco, Chile

© 2018 Elsevier LtdMissing data from air quality datasets is a common problem, but is much more severe in small cities or localities. This poses a great challenge for environmental epidemiology as high exposures to pollutants worldwide occur in these settings and gaps in datasets hinder health studies that could later inform local and international policies. Here, we propose the use of imputation methods as a tool to reconstruct air quality datasets and have applied this approach to an air quality dataset in Temuco, a mid-size city in Chile as a case-study. We attempted to reconstruct the database comparing five approaches: mean imputation, conditional mean imputation, K-Nearest Neighbor imputation, multiple imputation and Bayesian Principal Component Analysis imputation. As a base for the imputation methods, linear regression models were fitted for PM2.5 against other air quality and meteorological variables. Methods were challenged against validation sets where data was removed arti

Nivel de sesgos cognitivos de representatividad y confirmación en estudiantes de Psicología de tres universidades del Bío-Bío

Cognitive biases are unreasonable ways of making decisions, often in a one-sided way. The objective of this research was to describe the level of representativeness and confirmation biases in Chilean psychology students, in order to know how this phenomenon occurs. The participants were 198 psychology students from three universities in southern Chile. The instrument was based on two cognitive tasks derived from Kanheman and Tversky. The data were analyzed through descriptive statistics and mean differences. The results indicate a high level of biases in the groups of students, in the two tasks evaluated; the representativeness bias presents differences among universities only in sub-task 1, as well as in task 2, related to confirmation bias. Likewise, there are differences in representation bias according to age and sex. The need to strengthen reasoning skills in the initial training of future psychologists, in order to improve skills related to decision making in the professional field is concluded.Los sesgos cognitivos son formas no razonadas de tomar decisiones, a menudo de manera parcializada. El objetivo de esta investigación fue describir el nivel de sesgos de representatividad y confirmación en estudiantes de psicología chilenos, para conocer cómo se presenta este fenómeno. Los participantes fueron 198 estudiantes de psicología, de tres universidades del sur de Chile. El instrumento se basó en dos tareas cognitivas derivadas de Kanheman y Tversky; se analizaron los datos con estadística descriptiva y diferencias de medias. Los resultados indican alto nivel de sesgos en los grupos de estudiantes, en las dos tareas evaluadas; el sesgo de representatividad presenta diferencias entre universidades, solo en la subtarea 1, así como en la tarea 2, relacionada con sesgo de confirmación; así mismo se observan diferencias en sesgo de representación según edad y sexo. Se concluye la necesidad de fortalecer habilidades de razonamiento en la formación inicial de los futuros psicólogos y psicólogas, con la finalidad de mejorar las habilidades relacionadas con la toma de decisiones en el campo profesional