Diluting organic molecules in a polymer matrix material suppresses non-radiative behavior, leading to biluminescence, wherein light is emitted efficiently from both singlet and triplet states. In summary, biluminescence has developed into a thoroughly optimized and unique emissive system. Among the characteristics obtained through this system, the most significant is the ability of biluminophores to offer direct access to the radiative states of both spin manifolds (singlets and triplets) in organic molecules without the requirement for special or complex material combinations. As a result, an exciton is given the chance to re-emit its energy, regardless of its initial state. In future work, we intend to increase the toolset of organic biluminophores by screening materials to determine the structure-property relationships behind persistent phosphorescence, and to identify molecular building blocks that are suitable for the development of future materials. In addition, we will intensify our exploration of biluminescence for future applications (e.g., sensing).

Abstract: For the first time a comprehensive life cycle assessment (LCA) is reported of a large-area perovskite/Si tandem photovoltaic (PV) module of about 2 m², with an assumed power conversion efficiency of 30%, 30 years lifetime and an annual degradation of 0.5%, manufactured in a 1 GW production plant. By means of the LCA method, we calculate the contribution to the International Reference Life Cycle Data System (ILCD) impact categories associated with a perovskite/Si tandem PV system compared with a passivated emitter and rear cell (PERC) used as reference. We consider a functional unit of 1 kWh of generated direct current electrical energy from the tandem module over its lifetime. It was found that the most significant environmental hotspots are the silicon wafer production and the balance of system (BOS), especially the mounting system, inverter and electric installation. Overall, the impact contributions to the environment caused by the perovskite sub-module are below 1% throughout all the ILCD categories in focus: climate change, freshwater ecotoxicity, water resource depletion and human toxicity. Even the contribution of lead to human toxicity is just about 0.01%. For all the impacts assessed, the perovskite/Si tandem shows a decrease of between 17-20% of the contributions to each impact category compared to the PERC-module based reference PV system, if the Si bottom sub-module has an initial cell efficiency of at least 22% with 1% cell-to-module (CTM) loss, and the perovskite top sub-module has a minimum initial cell efficiency of 18% with at most 5% CTM loss and a transmittance near IR region larger than 80%. The key result found in this work is the relevance of the performance and reliability of the PV system to achieve lower environmental impacts. A comparison between optimistic, realistic, and pessimistic scenarios was performed to investigate this matter: in the worst-case scenario, the environmental impact of the PV tandem system would have a general 50% increase throughout all ILCD impact categories against the realistic case, whereas in the optimistic one, the results suggest a reduction of 46% to the global impact contributions, compared to the realistic scenario.

Resumen: Las aplicaciones de la electrónica exigen mayor eficiencia de los dispositivos electrónicos que se utilizan hoy en día. Entre los aspectos mas importantes esta el área ocupada por un circuito: Se busca que los dispositivos electrónicos ocupen el menor espacio posible. La tecnología que se utiliza hoy en día para fabricar dispositivos semiconductores está llegando a un punto limite, donde cada vez es mas difícil obtener reducción en el tamaño sin afectar otras características del dispositivo. La nanoelectrónica está evolucionando a un punto donde se hace posible la construcción de dispositivos semiconductores que presenten mejores características que los fabricados en la actualidad. Este documento muestra una revisión bibliográfica sobre nanotecnología, con el fin de presentar una propuesta de investigación para implementar transistores basados en nanotubos de carbono. Este trabajo está en su fase inicial, se espera que a finales del 2009 se tenga una metodología de implementación de transistores utilizando nanotecnología.

Abstract: La fabricación de las celdas fotovoltaicas inorgánicas son aquellas cuyo semiconductor es a base de material inorgánico (Si, AsGa, CuInS2, CIS, CdTe), son poco económicas, por ende, es necesario hallar una manera de producir celdas solares sin que la inversión económica sea costosa. Debido a esta dificultad tecnológica, se ha optado por usar semiconductores orgánicos en la fabricación de las celdas. Los paneles solares orgánicos no se contemplan como un sustituto a los de silicio como material semiconductor, sino un complemento para crear mejores fuentes de energía. En este caso, se plantea el uso de los nanotubos de carbono (CNT) como material semiconductor en la fabricación de celdas fotovoltaicas orgánicas.

Abstract: One of the strategies to improve governments’ allocation of resources, particularly when these are insufficient to meet all the public needs, is the use of targeting indices. Generally, a targeting index is a linear combination of wellbeing indicators (for example years of education, dwelling conditions, and so forth) that orders the members of the population according to their living conditions to classify and identify the beneficiaries of social programmes. The weighting method that we propose maximises a function that depends on the number of poor beneficiaries, by income and/or expenditure, given some normative restrictions. Therefore, the indices designed with this method target poor people taking into consideration not only the income dimension, but also other dimensions, such as health, nutrition, and dwelling, although they are not correlated with income and/or correlated with one another. The method for taking these dimensions into account is to specify weighting restrictions by an indicator of wellbeing. In other words, we establish maximum and minimum values for the weights according to the number of indicators and the needs of social programmes. These values maintain the balance between income-based weights and normative weights. Because of these characteristics, we call our method Maximising Poor Beneficiaries with Normative Restrictions (MPBR). The algorithm behind MPBR can maximises or minimises any function. For instance, in the first exercise of this study, it exclusively counts the number of expenditure -poor beneficiaries, and in the second it contemplates both income-poor and expenditure-poor beneficiaries, given double weight to those that meet both conditions - thus the poorest of the poor households become the first beneficiaries of social programmes-. We find that when the function to maximise counts exclusively the number of income-poor (or expenditure-poor) households before a cutoff, it is equivalent to minimising the IE (Inclusion error) and EE (Exclusion error). In fact, we theoretically and empirically demonstrate that the models that minimise the IE and EE (considering income-poor or expenditure-poor households) are probabilistic models. Therefore, we conclude that probabilistic models are a useful tool to determine approximately the minimum IE and EE that can be obtained with a set of indicators. Applying MPBR, we find that when the increase in an indicator of wellbeing statistically increases the probability of not being expenditure-poor, the weight of the indicator converges to a specific positive value to maximise the number of expenditure-poor beneficiaries; in contrast, if the increase in an indicator statistically decreases this probability, the weight of the indicator converges to the minimum allowed weight. In the case in which the indicator is not statistically significant in the probabilistic model, its weight does not converge to a specific value. However, when the weighting restrictions become stronger (for example a greater minimum weight), most of the weights converge to a value. In a comparison of MPBR with other weighting methods (for example PCA and normative method), we conclude that the index estimated with MPBR has a smaller IE and EE and distributes the weights between indicators more equitably than the indices calculated with other methods.

Abstract: Because only limited research has been done on base geometry effects on pile base resistance, design methods used in practice for full-displacement, partial-displacement, and non-displacement piles in sand do not consider these effects on base resistance calculations. In this paper, the effect of base geometry on pile resistance is studied by performing a series of tests in a half-cylindrical calibration chamber that allows observation of the sand domain through the chamber symmetry plane during installation and loading. Two model piles, one with a flat base and one with a conical base with an apex angle of 60°, were installed and load-tested in dense and medium dense sand samples. Digital images taken during loading of the model piles were processed using the Digital Image Correlation (DIC) technique. Detailed displacement and strain fields obtained with the DIC technique and base resistance measurements demonstrate that the addition of a conical base to a pile changes the deformation pattern in the sand below the base during loading. Furthermore, the base resistances of both the jacked and pre-installed model piles with a conical base were less than those for the piles with flat base for the same conditions, with the corresponding ratio ranging from 0.64 to 0.78 at relative displacement levels less than or equal to 10% of the diameter B of the model pile and from 0.70 to 0.84 at greater relative displacements. The results have implications also for the use of cone resistance from cone penetration test (CPT) in pile base resistance estimation. Resumen: Debido a que solo se ha realizado una investigación limitada sobre los efectos de la geometría de la base en la resistencia de la base del pilote, los métodos de diseño utilizados en la práctica para pilotes de desplazamiento total, desplazamiento parcial y sin desplazamiento en arena no consideran estos efectos en los cálculos de resistencia de la base. En este trabajo se estudia el efecto de la geometría de la base sobre la resistencia del pilote mediante la realización de una serie de ensayos en una cámara de calibración semicilíndrica que permite la observación del dominio de arena a través del plano de simetría de la cámara durante la instalación y carga. Se instalaron dos pilotes modelo, uno con base plana y otro con base cónica con un ángulo de vértice de 60 °, y se sometieron a prueba de carga en muestras de arena densa y medianamente densas. Las imágenes digitales tomadas durante la carga de los pilotes se procesaron utilizando la técnica de Correlación de imagen digital (DIC). Los campos detallados de desplazamiento y deformación obtenidos con la técnica DIC y las mediciones de resistencia de la base demuestran que la adición de una base cónica a un pilote cambia el patrón de deformación en la arena debajo de la base durante la carga. Además, las resistencias de la base tanto de los pilotes instalados mediante un jacking system y los pilotes preinstalados con base cónica fueron menores que las de los pilotes con base plana para las mismas condiciones, con la relación correspondiente que variaba de 0,64 a 0,78 a niveles de desplazamiento relativo menores que o igual al 10% del diámetro B del pilote y de 0,70 a 0,84 a mayores desplazamientos relativos. Los resultados también tienen implicaciones para el uso de la resistencia del cono obtenida de la prueba de penetración del cono (CPT) en la estimación de la resistencia de la base del pilote.

Abstract: Este artículo analiza el impacto de la política costarricense de apoyo al turismo sostenible, y en particular con el sistema de Certificación para la Sostenibilidad Turística (CST) del Instituto Costarricense de Turismo (ICT) en la innovación en servicios, procesos, mercadeo y organización de las empresas hoteleras del país. Se indagaron las causas y motivaciones para hacer cambios e introducir nuevos atributos dentro de la empresa. En la primera fase, se condujo encuestas con el 27% de todos los hoteles con declaratoria turística en Costa Rica y el 48% de los certificados con CST, para investigar los determinantes de la innovación y de la búsqueda de la certificación de sostenibilidad. Se aplicaron herramientas estadísticas para analizar diferencias entre los hoteles con y sin CST, así como la correlación de los determinantes de la innovación con el grado de innovación. Posteriormente se entrevistaron a seis hoteleros de diversos tipos para profundizar sobre las innovaciones realizadas, los determinantes y motivaciones. Los resultados indican que la certificación es un instrumento para ayudar a los gerentes a mejorar sustancialmente sus empresas, en términos de servicios, procesos, estructura interna y ahorros en agua y energía. Los hoteles con CST demuestren una tasa de ocupación 8% más alto que los hoteles no certificados, con un valor de p=0,01. No se evidenció una diferencia en innovación en mercadeo entre los hoteles con y sin CST.

Abstract: Land disputes between indigenous communities and peasants in Colombia are not something new. The scenario is almost the same: aboriginal communities conflicting with peasants and farmers for a territory in which to live. The issue has not been completely explored. In fact, analysis regarding territorial conflicts between indigenous peoples and farmers in Colombia remains insufficient because it is conservative when criticizing the institutional approaches to the conflict; it does not consider international examples; and what is worse, it lacks objectivity because the author usually takes a position in the conflict (commonly pro-indigenous). The specific case that I chose to study in this paper takes place in the northeast region of Colombia known as Catatumbo. The Barí peoples are an aboriginal group who have disputed farmer’s claims since the 1990s, in an effort to secure their property titles. The land dispute reached such magnitude that it was studied by the Colombian Constitutional Court in 2017. However, after many attempts to solve the territorial dispute, the problem persists. In this article, I explore alternative approaches to land disputes between farmers and native communities in Colombia. First, I give a general characterization of the conflict itself and the parties involved. Next, I present the existing theoretical and legal framework to approach the land dispute, emphasizing my research in the disparity between the rights of indigenous peoples and peasants regarding land access. Also, I argue that the existing institutional framework is naively biased to favor indigenous claims over farmers' demands. Finally, I compare examples from Common Law countries that could be useful to approach proportionality tests differently.

Abstract: The effort of universities, companies, and the state in Colombia to face home-made AP landmines has generated useful solutions and studies for many projects developed in the last decade, including demining processes in Colombia. Antipersonnel mines have changed in the last 15 years, due to the intermittent nature of our internal conflict. For example, as Descontamina Colombia mentions on its website, non-state armed groups cut the detonator containing the primary explosive to decrease the metal in the mine. This paper shows the aspects of the conflict that have affected humanitarian demining in Colombia, which help in the design and construction of technological devices. This article does not attempt to describe each of the typical technologies in humanitarian demining processes, but rather to show the characteristics considered in the design of two detection devices aimed at detecting home-made AP landmines.

Abstract: BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder associated with significant morbidity and mortality that may affect over 5% of children and approximately 2.8% of adults worldwide. Pharmacological and behavioral therapies for ADHD exist, but critical symptoms such as dysexecutive deficits remain unaffected. In a randomized, sham-controlled, double-blind, crossover mechanistic study, we assessed the cognitive and physiological effects of transcranial direct current stimulation (tDCS) in 40 adult patients with ADHD in order to identify diagnostic (cross-sectional) and treatment biomarkers (targets). METHODS: Patients performed three experimental sessions in which they received 30 minutes of 2 mA anodal tDCS targeting the left dorsolateral prefrontal cortex, 30 minutes of 2 mA anodal tDCS targeting the right dorsolateral prefrontal cortex, and 30 minutes of sham. Before and after each session, half the patients completed the Eriksen flanker task and the other half completed the stop signal task while we assessed behavior (reaction time, accuracy) and neurophysiology (event-related potentials). RESULTS: Anodal tDCS to the left dorsolateral prefrontal cortex modulated cognitive (reaction time) and physiological (P300 amplitude) measures in the Eriksen flanker task in a state-dependent manner, but no effects were found in the stop signal reaction time of the stop signal task. CONCLUSIONS: These findings show procognitive effects in ADHD associated with the modulation of event-related potential signatures of cognitive control, linking target engagement with cognitive benefit, proving the value of eventrelated potentials as cross-sectional biomarkers of executive performance, and mechanistically supporting the statedependent nature of tDCS. We interpret these results as an improvement in cognitive control but not action cancellation, supporting the existence of different impulsivity constructs with overlapping but distinct anatomical substrates, and highlighting the implications for the development of individualized therapeutics.