When omnigeneity fails

A generic non-symmetric magnetic field does not confine magnetized charged particles for long times due to secular magnetic drifts. Stellarator magnetic fields should be omnigeneous (that is, designed such that the secular drifts vanish), but perfect omnigeneity is technically impossible. There always are small deviations from omnigeneity that necessarily have large gradients. The amplification of the energy flux caused by a deviation of size $\epsilon$ is calculated and it is shown that the scaling with $\epsilon$ of the amplification factor can be as large as linear. In opposition to common wisdom, most of the transport is not due to particles trapped in ripple wells, but to the perturbed motion of particles trapped in the omnigeneous magnetic wells around their bounce points.Comment: 6 pages, 2 figure

A Taste of Cuba: A Journey through Cuba and Its Savory Cuisine

From the leading photographer of Cuba, A Taste of Cuba is a stunning culinary and visual journey through Cuba that presents 75 authentic, never-before-shared recipes from the world\u27s most inventive chefs. In a country shrouded in secrecy, a mouthwatering, but little-known food scene is emerging. A Taste of Cuba offers unprecedented access into the kitchens of Cuba\u27s top chefs, where the country\u27s most delectable dishes are created and where the chefs will share for the very first time, their brilliant techniques, inspiration, and best recipes.https://digitalcommons.fiu.edu/cri_events/1413/thumbnail.jp

Towards Smarter Management of Overtourism in Historic Centres Through Visitor-Flow Monitoring

Historic centres are highly regarded destinations for watching and even participating in diverse and unique forms of cultural expression. Cultural tourism, according to the World Tourism Organization (UNWTO), is an important and consolidated tourism sector and its strong growth is expected to continue over the coming years. Tourism, the much dreamt of redeemer for historic centres, also represents one of the main threats to heritage conservation: visitors can dynamize an economy, yet the rapid growth of tourism often has negative effects on both built heritage and the lives of local inhabitants. Knowledge of occupancy levels and flows of visiting tourists is key to the efficient management of tourism; the new technologies—the Internet of Things (IoT), big data, and geographic information systems (GIS)—when combined in interconnected networks represent a qualitative leap forward, compared to traditional methods of estimating locations and flows. A methodology is described in this paper for the management of tourism flows that is designed to promote sustainable tourism in historic centres through intelligent support mechanisms. As part of the Smart Heritage City (SHCITY) project, a collection system for visitors is developed. Following data collection via monitoring equipment, the analysis of a set of quantitative indicators yields information that can then be used to analyse visitor flows; enabling city managers to make management decisions when the tourism-carrying capacity is exceeded and gives way to overtourism.Funded by the Interreg Sudoe Programme of the European Regional Development Funds (ERDF

Distributed Correlation-Based Feature Selection in Spark

CFS (Correlation-Based Feature Selection) is an FS algorithm that has been successfully applied to classification problems in many domains. We describe Distributed CFS (DiCFS) as a completely redesigned, scalable, parallel and distributed version of the CFS algorithm, capable of dealing with the large volumes of data typical of big data applications. Two versions of the algorithm were implemented and compared using the Apache Spark cluster computing model, currently gaining popularity due to its much faster processing times than Hadoop's MapReduce model. We tested our algorithms on four publicly available datasets, each consisting of a large number of instances and two also consisting of a large number of features. The results show that our algorithms were superior in terms of both time-efficiency and scalability. In leveraging a computer cluster, they were able to handle larger datasets than the non-distributed WEKA version while maintaining the quality of the results, i.e., exactly the same features were returned by our algorithms when compared to the original algorithm available in WEKA.Comment: 25 pages, 5 figure

Do theoretical physicists care about the protein-folding problem?

The prediction of the biologically active native conformation of a protein is one of the fundamental challenges of structural biology. This problem remains yet unsolved mainly due to three factors: the partial knowledge of the effective free energy function that governs the folding process, the enormous size of the conformational space of a protein and, finally, the relatively small differences of energy between conformations, in particular, between the native one and the ones that make up the unfolded state. Herein, we recall the importance of taking into account, in a detailed manner, the many interactions involved in the protein folding problem (such as steric volume exclusion, Ramachandran forces, hydrogen bonds, weakly polar interactions, coulombic energy or hydrophobic attraction) and we propose a strategy to effectively construct a free energy function that, including the effects of the solvent, could be numerically tractable. It must be pointed out that, since the internal free energy function that is mainly described does not include the constraints of the native conformation, it could only help to reach the 'molten globule' state. We also discuss about the limits and the lacks from which suffer the simple models that we, physicists, love so much.Comment: 27 pages, 4 figures, LaTeX file, aipproc package. To be published in the book: "Meeting on Fundamental Physics 'Alberto Galindo'", Alvarez-Estrada R. F. et al. (Ed.), Madrid: Aula Documental, 200

Los NFT y su incorporación al mercado del arte español: el caso de artistas contemporáneos participantes en ARCO Madrid

Since their spectacular appearance in the art system in 2021, non-fungible tokens or NFT have attracted the attention of researchers in the field of art history, the art market and social sciences, as well as of every agent within the art system. This article studies the relationships with NFTs of a group of Spanish visual artists participating in the ARCO Madrid fair in 2020, that is, the last edition before its irruption in 2021 into the art market. Thus, through the formulation of an online survey conducted in 2023, the impact of the advent of this technology on their artistic practice is analyzed. The results provide both qualitative and quantitative information that demonstrate the still low penetration of NFT in 2023 among the selected group of artists and explores the main barriers that hinder the incorporation of this technology in their work.Desde su espectacular aparición en el sistema del arte en 2021, los non-fungible tokens o NFT han acaparado la atención de investigadores del campo de la historia y el mercado del arte, de las ciencias sociales, así como de todos los agentes del sistema del arte. Este artículo estudia las relaciones con los NFT de un conjunto de artistas visuales españoles participantes en la feria ARCO Madrid en 2020, es decir, la última edición antes de su irrupción en 2021 en el mercado del arte. Así, mediante la elaboración de una encuesta online realizada en 2023, se analiza el impacto de la llegada de esta tecnología en su práctica artística. Los resultados aportan información tanto cualitativa como cuantitativa que demuestra la aún escasa penetración de los NFT en 2023 entre el conjunto de artistas seleccionado, al tiempo que explora las principales barreras que dificultan la incorporación a su trabajo

Development of low-pH cementitious materials for HLRW repositories. Resistance against ground waters aggression

One of the most accepted engineering construction concepts of underground repositories for high radioactive waste considers the use of low-pH cementitious materials. This paper deals with the design of those based on Ordinary Portland Cements with high contents of silica fume and/or fly ashes that modify most of the concrete “standard” properties, the pore fluid composition and the microstructure of the hydrated products. Their resistance to long-term groundwater aggression is also evaluated. The results show that the use of OPC cement binders with high silica content produces low-pH pore waters and the microstructure of these cement pastes is different from the conventional OPC ones, generating C–S–H gels with lower CaO/SiO2 ratios that possibly bind alkali ions. Leaching tests show a good resistance of low-pH concretes against groundwater aggression although an altered front can be observe

Durabilidad de hormigones autocompactantes con prestaciones especiales expuestos en atmósferas marinas y urbanas.

El hormigón autocompactante es aún una tecnología relativamente nueva y se tiene un escaso conocimiento acerca del comportamiento frente a durabilidad de este material. Sin embargo, la creciente tendencia al desarrollo de códigos y normativas que contemplan tanto la durabilidad del hormigón desde la fase de diseño como el empleo de nuevos materiales, implica un mayor conocimiento de las propiedades durables de este tipo de hormigón. En el presente trabajo se presentan los resultados obtenidos a partir de un estudio de durabilidad con hormigón autocompactante convencional fabricado con filler calizo, así como hormigones autocompactantes, con la misma dosificación pero modificados bien con incorporación de fibras (metálicas y poliméricas) o bien con sustitución del filler calizo por residuos de lodos de naturaleza caliza. Se han llevado a cabo tanto ensayos en laboratorio para determinación de indicadores de durabilidad como ensayos de exposición durante un año a atmósferas naturales (marina y urbana con distinta humedad relativa). Los indicadores de durabilidad analizados arrojan una elevada calidad de los distintos hormigones autocompactantes, lo cual se confirma a partir de ensayos de exposición en atmósferas reales. Si bien no se ha visto que la incorporación de fibras influya en la interacción de este material con el cloruro ni con el CO2, la sustitución del filler calizo por residuo de lodo indica un ligero aumento en la carbonatación y el transporte de cloruros

Perspectivas de solución, ante la deforestación por factores de presión, en la Amazonía peruana. Caso departamento de Ucayali, 2022

La presente investigación abordó el tema acerca de la deforestación y tuvo como objetivo analizar los principales factores de presión de la deforestación en la amazonia peruana: caso departamento de Ucayali. Metodológicamente fue de enfoque cualitativo, de tipo básico y diseño fenomenológico, para el recojo de información se utilizó la entrevista a profundidad como técnica, siendo el cuestionario semi estructurado, el instrumento se aplicó a cinco informantes conocedores y especialistas en el manejo de aspectos referidos a la deforestación en la zona de Ucayali, los mismos que perteneces al Ministerio de Agricultura. Del análisis de los resultados y la triangulación, respecto a los factores de presión vinculados a la deforestación en la amazonía peruana, principalmente en el departamento de Ucayali, se concluyó que el factor de presión de mayor impacto, fue la presencia de la ganadería, agricultura y actividades de desbosque con fines energéticos, existiendo además, otros factores como la apertura de caminos y carreteras, extracción de madera, incendios y asentamientos humanos, que incrementan la deforestación; sin embargo, de acuerdo con los entrevistados, en relación a las perspectivas de solución, los gobiernos regionales y locales han realizado insuficientes o nulas acciones para detener, controlar o revertir dicho problema, siendo la informalidad otro de los factores imperantes en la zona dificultando la solución a la deforestació