Boundary condition and geometry engineering in electronic hydrodynamics

We analyze the role of boundary geometry in viscous electronic hydrodynamics. We address the twin questions of how boundary geometry impacts flow profiles, and how one can engineer boundary conditions -- in particular the effective slip parameter -- to manipulate the flow in a controlled way. We first propose a micropatterned geometry involving finned barriers, for which we show by an explicit solution that one can obtain effectively no-slip boundary conditions regardless of the detailed microscopic nature of the channel surface. Next we analyse the role of mesoscopic boundary curvature on the effective slip length, in particular its impact on the Gurzhi effect. Finally we investigate a hydrodynamic flow through a circular junction, providing a solution, which suggests an experimental set-up for determining the slip parameter. We find that its transport properties differ qualitatively from the case of ballistic conduction, and thus presents a promising setting for distinguishing the two.Comment: 9 pages, 15 figures, 5 appendice

Quantum phases of semiconductor moiré materials

Moiré materials have been established as a new paradigm for realizing exotic phases of matter, attracting prominent attention due to their unprecedented tunability. Notably, moiré materials based on semiconductor transition metal dichalcogenides (TMDs) provide a robust platform to investigate quantum phases of matter, encompassing states that emerge in both topologically trivial and non-trivial flat bands. In this thesis we present a theoretical study of the many-body physics of semiconductor moiré materials, shedding light on the microscopic mechanisms underlying the diverse quantum phases observed in experiments. Through a combination of numerical and analytical approaches, we investigate the correlated phases of moiré Hubbard simulators, as well as the correlated phases of topological moiré TMDs, across several band fillings. Particularly, we address the properties and stability regimes of phases such as Mott insulators, generalized Wigner crystals, and fractional Chern insulators. The most relevant original contributions of this thesis include: I) Demonstrating how the extended nature of Wannier functions in moiré Hubbard systems makes nonlocal interactions relevant, thus favoring the emergence of new phases, and II) Microscopically explaining the origin of a magic angle with almost vanishing band width and nearly ideal quantum geometry in TMD homobilayers.Physic

Simple regular black hole with logarithmic entropy correction

A simple regular black hole solution satisfying the weak energy condition is obtained within Einstein--non--linear electrodynamics theory. We have computed the thermodynamic properties of this black hole by a careful analysis of the horizons and we have found that the usual Bekenstein--Hawking entropy gets corrected by a logarithmic term. Therefore, in this sense our model realizes some quantum gravity predictions which add this kind of correction to the black hole entropy. In particular, we have established some similitudes between our model and a quadratic generalized uncertainty principle. This similitude has been confirmed by the existence of a remnant, which prevents complete evaporation, in agreement with the quadratic generalized uncertainty principle case

Magnetism and Quantum Melting in Moir\'e-Material Wigner Crystals

Recent experiments have established that semiconductor-based moir\'e materials can host incompressible states at a series of fractional moir\'e-miniband fillings. These states have been identified as generalized Wigner crystals in which electrons localize on a subset of the available triangular-lattice moir\'e superlattice sites. In this article, we use momentum-space exact diagonalization to investigate the many-body ground state evolution at rational fillings from the weak-hopping classical lattice gas limit, in which only spin degrees-of-freedom are active at low energies, to the strong-hopping metallic regime where the Wigner crystals melt. We specifically address the nature of the magnetic ground states of the generalized Wigner crystals at fillings $\nu$ = 1/3 and $\nu$ = 2/3.Comment: 12 pages, 8 figure

Itinerant ferromagnetism in transition metal dichalcogenides moir\'e superlattices

Moir\'e materials are artificial crystals formed at van der Waals heterojunctions that have emerged as a highly tunable platform to realize much of the rich quantum physics of electrons in atomic scale solids, also providing opportunities to discover new quantum phases of matter. Here we use finite-size exact diagonalization methods to explore the physics of single-band itinerant electron ferromagnetism in semiconductor moir\'e materials. We predict where ferromagnetism is likely to occur in triangular-lattice moir\'e systems, and where it is likely to yield the highest Curie temperatures.Comment: 15 pages, 14 figure

Pressure--enhanced fractional Chern insulators in moir\'e transition metal dichalcogenides along a magic line

We show that pressure applied to twisted WSe$_2$ can enhance the many-body gap and region of stability of a fractional Chern insulator at filling $\nu = 1/3$. Our results are based on exact diagonalization of a continuum model, whose pressure-dependence is obtained through {\it ab initio} methods. We interpret our results in terms of a {\it magic line} in the pressure-{\it vs}-twist angle phase diagram: along the magic line, the bandwidth of the topmost moir\'e valence band is minimized while simultaneously its quantum geometry nearly resembles that of an ideal Chern band. We expect our results to generalize to other twisted transition metal dichalcogenide homobilayers.Comment: 11 pages, 9 figure

La Educación Inclusiva: Una Mirada desde las Concepciones y Prácticas de la Docencia en Colombia

Inclusive education promotes educational institutions to transform their curricula, teaching and learning processes, and resources so that every student can receive a quality education, develop their full potential, and be valued and respected in their differences. This requires an inclusive teacher capable of creating and facilitating these environments of respect and acceptance for individuals. This article presents the conceptions that teachers in some institutions in Colombia have about inclusive education and how these impact their pedagogical practices, in such a way that these findings and recommendations can strengthen strategies related to inclusive education, divided into two blocks: conceptions and practices of inclusive education among elementary and secondary school teachers. The analysis was conducted using a qualitative, descriptive approach based on 118 interviews with elementary and secondary school teachers. This analysis revealed that teachers have normative and conceptual elements that can be opportunities for improvement in the implementation of strategies and environments for inclusive education. However, continuous training and alignment with the daily tasks of teaching are required.La educación inclusiva promueve a las instituciones educativas a transformar sus currículos, sus procesos de enseñanza y aprendizaje y los recursos para que cada estudiante pueda recibir una educación de calidad, desarrollar al máximo su potencial, ser valorado y respetado en sus diferencias. Para ello se requiere de un docente inclusivo capaz de generar y posibilitar estos ambientes de respeto y acogida de los individuos. El artículo presenta las concepciones que tienen los docentes de algunas instituciones de Colombia sobre educación inclusiva y cómo éstas inciden en sus prácticas pedagógicas, de tal forma que estos hallazgos y recomendaciones permitan fortalecer las estrategias relacionadas con la educación inclusiva; dividiéndose en dos bloques: concepciones y prácticas de la educación inclusiva de los docentes de básica y media. Se realizó desde un enfoque cualitativo, descriptivo el análisis de 118 entrevistas realizadas a docentes de básica y media. dicho análisis evidenció que los docentes poseen elementos normativos y conceptuales que se convierten en oportunidades de mejora para la implementación de estrategias y ambientes para la educación inclusiva. No obstante, se requiere una capacitación continua y una coherencia con el día a día del quehacer docente

Mayores niveles de transporte activo se asocian a un menor nivel de adiposidad y menor riesgo de obesidad: resultados de la Encuesta Nacional de Salud 2009-2010 = Association of active commuting with obesity: findings from the Chilean National Health Survey 2009-2010

Background: Active commuting is associated with a lower risk for obesity in developed countries. Aim: To investigate the association between active commuting and obesity risk in Chile. Material and Methods: Active commuting was measured using the Global Physical Activity Questionnaire (GPAQ v2) in 5,293 participants from the Chilean National Health Survey 2009-2010. Body mass index (BMI) and waist circumference (WC) were the study outcomes. The association between active commuting and obesity was investigated using linear and logistic regression analysis. Results: Thirty four percent of responders [95% confidence intervals (CI): 32.6-35.1] were passive commuters. Active commuters had a lower BMI and WC than their passive counterparts. Thirty minutes increment in active commuting were associated with a −0.20 kg.m-2 lower BMI [95% CI: −0.33 to −0.07, p < 0.01] and a −076 cm lower WC [95% CI: −1.08 to −0.43, p < 0.01]. The odds of having a BMI > 25 kg.m-2 was 0.93 [95% CI: 0.88 to 0.98, p = 0.01] per every 30 minutes’ increment in active commuting, whereas the odds for central obesity was 0.87 [95% CI: 0.82 to 0.92, p < 0.01]. Conclusions: Active commuting is associated with a lower adiposity and lower risk for obesity in Chilean adults

Factores asociados a inactividad física en Chile: resultados de la Encuesta Nacional de Salud 2009-2010 = Correlates of physical inactivity: Findings from the Chilean National Health Survey 2009-2010

Background: Physical inactivity is an important risk factor for cardiovascular diseases. Aim: To identify factors associated with physical inactivity in Chilean adults. Material and Methods: Participants from the Chilean Health Survey (5,133 individuals) were included in this study. Physical activity was measured using the Global physical activity questionnaire (GPAQ). Physical inactivity was defined as < 600 MET. min.week−1 of moderate to vigorous intensity physical activity. Logistic regression was used to identify correlates of physical inactivity. Results: The main finding of this study were that women (odds ratio (OR): 1.51 [95% confidence intervals (CI): 1.32-1.72]) were more likely to be inactive compared to men and that older adults were more likely to be inactive than their younger or middle age counterparts (OR: 3.06 [95% CI: 2.45-3.82]). Other correlates of physical inactivity were individuals with obesity (OR: 1.43 [95% CI: 1.20-1.70]), diabetes (OR: 1.96 [95% CI: 1.61-2.38]), hypertension (OR: 1.72 [95% CI: 1.50-1.97]), metabolic syndrome (OR: 1.42 [95% IC: 1.18-1.70]), a low education level (OR: 1.26 [95% CI: 1.06-1.49]) and higher levels of sedentary behavior (OR: 2.77 [95% CI: 2.36-3.25]). Conclusions: Women, older people and sedentary subjects with chronic non-transmissible conditions are at higher risk of being physically inactive