Solving the quantum dimer and six-vertex models one electric field line at a time

The nature and the very existence of the resonant plaquette valence bond state that separates the classical columnar phase and the Rokhsar-Kivelson point in the quantum dimer model remains unsettled. Here we take a different line of attack on this model, and on the closely related six-vertex model, by exploiting the global conservation law of the number of electric field lines. This allows us to study a single fluctuating electric field line which we show maps exactly onto a one-dimensional spin chain. In the case of the six-vertex model, the electric field line maps onto the celebrated spin 1/2 XXZ model which can be solved exactly. In the quantum dimer model, the electric field line is mapped onto a two-leg spin 1/2 ladder, which we study using numerical exact diagonalization. Our findings are consistent with the existence of three distinct phases including a Luttinger liquid phase, the one-dimensional precursor to the two-dimensional plaquette valence bond solid. The uncanny resemblance of our quasi-one-dimensional electric field line problem to the full two-dimensional problem suggests that much of the behavior of the latter might be understood by thinking of it as a closely packed array of field lines which themselves are undergoing nontrivial phase transitions

Fault effect analysis based on elements loadability to evaluate reliability in power systems

This paper presents a fault effect analysis (FEA) based on element loadability as a complement tool to evaluate reliability and identify vulnerable points in power systems. The steps of the method are the calculation of overloaded elements after contingencies, determination of the FEA based on element loadability, selection of critical overloaded elements, and evaluation of system reliability by considering the energy not supplied (ENS). A simplified transmission and distribution (T and D) power system with 30 nodes was used as study case for the method. The results show that the loadability percentage of transformers and power lines are calculated successfully for the N-1 contingency analysis performed in the network and the method selects the elements with higher loadability values, evaluating the impact that each critical contingency generates on the power system reliability. The method can be used to prioritize remedial actions for critical elements on power systems

An effective procedure to design the layout of standard and enhanced mode-S multilateration systems for airport surveillance

In this paper, an effective procedure to emplace standard and enhanced mode-S multilateration stations for airport surveillance is studied and developed. This procedure is based on meta-heuristic optimization techniques, such as genetic algorithm (GA), and is intended to obtain useful parameters for an optimal system configuration that provides acceptable performance levels. Furthermore, the procedure developed here is able to evaluate and improve previous system designs, as well as possible system enhancements. Additionally, the design strategies to be used along with the procedure proposed here are fully described. Parameters such as the number of stations, the system geometry, the kind of measurements to be used, and the system accuracy are obtained taking into account the basic requirements such as the Line of Sight, the probability of detection, and the accuracy levels. © Cambridge University Press and the European Microwave Association, 2012

Coupling between annual and ENSO timescales in the malaria-climate association in Colombia.

We present evidence that the El Niño phenomenon intensifies the annual cycle of malaria cases for Plasmodium vivax and Plasmodium falciparum in endemic areas of Colombia as a consequence of concomitant anomalies in the normal annual cycle of temperature and precipitation. We used simultaneous analyses of both variables at both timescales, as well as correlation and power spectral analyses of detailed spatial (municipal) and temporal (monthly) records. During "normal years," endemic malaria in rural Colombia exhibits a clear-cut "normal" annual cycle, which is tightly associated with prevalent climatic conditions, mainly mean temperature, precipitation, dew point, and river discharges. During historical El Niño events (interannual time scale), the timing of malaria outbreaks does not change from the annual cycle, but the number of cases intensifies. Such anomalies are associated with a consistent pattern of hydrological and climatic anomalies: increase in mean temperature, decrease in precipitation, increase in dew point, and decrease in river discharges, all of which favor malaria transmission. Such coupling explains why the effect appears stronger and more persistent during the second half of El Niño's year (0), and during the first half of the year (+1). We illustrate this finding with data for diverse localities in Buenaventura (on the Pacific coast) and Caucasia (along the Cauca river floodplain), but conclusions have been found valid for multiple localities throughout endemic regions of Colombia. The identified coupling between annual and interannual timescales in the climate-malaria system shed new light toward understanding the exact linkages between environmental, entomological, and epidemiological factors conductive to malaria outbreaks, and also imposes the coupling of those timescales in public health intervention programs

Migración y salud, una mirada desde el Censo 2018 en Colombia

Introduction. The human being is characterized by having specific development spheres such as social, physical, family, spiritual and emotional.People known as migrants because they are outside their cultural, family and community sphere, and under atypical conditions they adopt new practices and styles of life, which causes risks to their own health and to the community by which they have been welcomed. Methodology. A descriptive study was carried out with the following variables from the 2018 Colombian census: five-year ages, sex, year of arrival in the country , any health problem in the last 30 days, main treatment of the health problem, attention to the health problem, quality of health service provision, any difficulty in their daily life, health insurance, barriers to access to services health, barriers to early childhood care services. Results. Health care for the migrant population in Colombia is not on the fringes of e the one that had its own population and there is no major difference in terms of quality and coverage, gender and access barriers, which are equal to the general population without differences with respect to the child population. Although health insurance is lower than the general population, only half of the migrants give formal treatment to their health problems. Conclusion. Specific policies should be established to promote health care for migrants, as this is a challenge for public health due to access policies and the care provided.Introducción. El ser humano se caracteriza por tener esferas de desarrollo especifico tales como social, física, familia, espiritual y emocional, Las personas conocidas como migrantes al estar fuera de su esfera cultural, familiar y comunitaria, y bajo condiciones atípicas adoptan nuevas prácticas y estilos de vida, lo que ocasiona riesgos para la salud propia y de la comunidad por la cual han sido acogidos. Metodología. Se realizó un estudio de tipo descriptivo con las siguientes variables del censo de Colombia de 2018: edades quinquenales, sexo, año de llegada al país, algún problema de salud en los últimos 30 días, tratamiento principal del problema de salud, atención del problema en salud, calidad de la prestación del servicio de salud, alguna dificultad en su vida diaria, aseguramiento en salud, barreras de acceso a los servicios de salud, barreras a servicios para cuidado de la primera infancia. Resultados. La atención en salud de la población migrante en Colombia no está al margen de la que tenía la población propia y no hay mayor diferencia en cuanto a calidad y cobertura, género y las barreras de acceso las cuales son iguales a la población en general sin diferencias con respecto a la población infantil. Aunque el aseguramiento en salud es menor que la población general solo la mitad de los migrantes dan un tratamiento formal a sus problemas de salud. Conclusión. Se deben establecer políticas específicas para promover el cuidado en salud de las personas migrantes al ser esto un desafío para la salud pública por las políticas de acceso y la atención brindada

A systems pharmacology model for inflammatory bowel disease

Motivation The literature on complex diseases is abundant but not always quantitative. This is particularly so for Inflammatory Bowel Disease (IBD), where many molecular pathways are qualitatively well described but this information cannot be used in traditional quantitative mathematical models employed in drug development. We propose the elaboration and validation of a logic network for IBD able to capture the information available in the literature that will facilitate the identification/validation of therapeutic targets. Results In this article, we propose a logic model for Inflammatory Bowel Disease (IBD) which consists of 43 nodes and 298 qualitative interactions. The model presented is able to describe the pathogenic mechanisms of the disorder and qualitatively describes the characteristic chronic inflammation. A perturbation analysis performed on the IBD network indicates that the model is robust. Also, as described in clinical trials, a simulation of anti-TNFα, anti-IL2 and Granulocyte and Monocyte Apheresis showed a decrease in the Metalloproteinases node (MMPs), which means a decrease in tissue damage. In contrast, as clinical trials have demonstrated, a simulation of anti-IL17 and anti-IFNγ or IL10 overexpression therapy did not show any major change in MMPs expression, as corresponds to a failed therapy. The model proved to be a promising in silico tool for the evaluation of potential therapeutic targets, the identification of new IBD biomarkers, the integration of IBD polymorphisms to anticipate responders and non-responders and can be reduced and transformed in quantitative model/s

Chicamocha Canyon Geopark project: A novel strategy for the socio-economic development of Santander (Colombia) through geoeducation, geotourism and geoconservation

The proposed Chicamocha Canyon Geopark project is starting its way for nomination as a UNESCO Global Geopark under the recognition of the Global Geoparks Network. This paper aims to present the justifications of establishing this geopark. It also assesses the potential role of a geopark figure in Santander as an urgent measure to promote the geoconservation of the Chicamocha Canyon territory. The success of this project will not only improve the living conditions of local communities, but also will be a reference model in terms of geological conservation at national and international level. The Chicamocha Canyon, where is proposed to develop this project, has a great potential for the development of the tourism industry due to climatic conditions of the region, besides possessing a rich cultural and natural heritage that needs to be enhanced and protected. Undoubtedly, this initiative should satisfy all the requirements to be a UNESCO Global Geopark, which include a delimited area that defines a territory, the occurrence of geological features of international importance with scientific, educational and aesthetic value, the presence of other types of heritage such as archaeological sites, as well as a proper access infrastructure that favors the socio-economic development of the region. In order to guarantee the successful consolidation of the proposed geopark within the defined territory, this initiative must count the strong support of the local communities and must involve stakeholders such as government authorities, academic and research institutions, and local businesses