CTZS Thin Films Grown by a Sequential Deposition of Precursors

A comparative study of the structural, optical and morphological properties of Cu2ZnSnS4 (CZTS) thin films prepared by two different techniques was performed. One consists of sequential evaporation of the elemental metallic precursors under a flux of sulphur supplied by evaporation from an effusion cell (physical vapor deposition-PVD) and the second one is a solution-based chemical route where thin layers of CuS, SnS and ZnS are deposited sequentially by diffusion membrane- assisted chemical bath deposition techniques; the membranes are used to optimize the kinetic growth through a moderate control of the release of the metal into CBD solution by osmosis. The present comparative study is helpful to the synthesis of kesterite nanostructured thin films.Comment: Published 201

Reflexiones sobre la política exterior de Taiwán: entre espacios reales e imaginados

This article analyses the relationship between the geographical context as a physical space and the historical narrative as an imagined space in the formation of Taiwanese national identity. Based on the theoretical proposal of constructivism, that emphasises the importance of identity in shaping the interests of the States, the article suggests that the geographical and historical conditions have enabled Taiwan to develop a different national identity from that of the Chinese. For this, the assumption is that the geographical context generates material conditions and social interactions, turning the territory into an “imagined” space. This immaterial space is, above all, the result of historical narratives. Thus, the elements that configure the Taiwanese identity affect the foreign policy of this State, particularly in the search for international recognition. The conclusion highlights how the case of Taiwan evidences the manner in which identity influences foreign policy.Este artículo analiza la relación entre el contexto geográfico como un espacio físico y la narrativa histórica como un espacio imaginado en la conformación de la identidad nacional taiwanesa. Basado en la propuesta teórica del constructivismo, que enfatiza la importancia de la identidad en la conformación de los intereses de los Estados, se propone que las condiciones geográficas e históricas de Taiwán han desarrollado una identidad nacional distinta y diferenciada de la identidad china. Para ello, se asume una visión que sugiere que el contexto geográfico no solo genera condiciones materiales, sino también posibilita una serie de interacciones sociales que convierten al territorio también en un espacio “imaginado”, el cual es el resultado de narrativas históricas. Así, los elementos que conforman la identidad taiwanesa inciden en la política exterior de este Estado, particularmente en el caso de la búsqueda el reconocimiento internacional. Como conclusión, se destaca la manera en que el caso de Taiwán evidencia la forma como la identidad influye en la política exterior

SMA-Based Muscle-Like Actuation in Biologically Inspired Robots: A State of the Art Review

New actuation technology in functional or "smart" materials has opened new horizons in robotics actuation systems. Materials such as piezo-electric fiber composites, electro-active polymers and shape memory alloys (SMA) are being investigated as promising alternatives to standard servomotor technology [52]. This paper focuses on the use of SMAs for building muscle-like actuators. SMAs are extremely cheap, easily available commercially and have the advantage of working at low voltages. The use of SMA provides a very interesting alternative to the mechanisms used by conventional actuators. SMAs allow to drastically reduce the size, weight and complexity of robotic systems. In fact, their large force-weight ratio, large life cycles, negligible volume, sensing capability and noise-free operation make possible the use of this technology for building a new class of actuation devices. Nonetheless, high power consumption and low bandwidth limit this technology for certain kind of applications. This presents a challenge that must be addressed from both materials and control perspectives in order to overcome these drawbacks. Here, the latter is tackled. It has been demonstrated that suitable control strategies and proper mechanical arrangements can dramatically improve on SMA performance, mostly in terms of actuation speed and limit cycles

A stopping rule for discounted Markov decision processes with finite action sets

summary:In a Discounted Markov Decision Process (DMDP) with finite action sets the Value Iteration Algorithm, under suitable conditions, leads to an optimal policy in a finite number of steps. Determining an upper bound on the necessary number of steps till gaining convergence is an issue of great theoretical and practical interest as it would provide a computationally feasible stopping rule for value iteration as an algorithm for finding an optimal policy. In this paper we find such a bound depending only on structural properties of the Markov Decision Process, under mild standard conditions and an additional "individuality" condition, which is of interest in its own. It should be mentioned that other authors find such kind of constants using non-structural information, i.e., information not immediately apparent from the Decision Process itself. The DMDP is required to fulfill an ergodicity condition and the corresponding ergodicity index plays a critical role in the upper bound

The Internationalization of Domestic Banks and the Credit Channel of Monetary Policy

How does the expansion of domestic banks in international markets affect the bank lending channel of monetary policy? Using bank-firm loan-level data, we find that loan growth and loan rates from international banks respond less to monetary policy changes than domestic banks and that internationalization partially mitigates the risk-taking channel of monetary policy. Banks with a large international presence tend to tolerate more their credit risk exposition relative to domestic banks. Moreover, international banks tend to rely more on foreign funding when policy rates change, allowing them to insulate better the monetary policy changes from their credit supply than domestic banks. This result is consistent with the predictions of the internal capital markets hypothesis. We also show that macroprudential FX regulation reduces banks with high FX exposition access to foreign funding, ultimately contributing to monetary policy transmission. Overall, our results suggest that the internationalization of banks lowers the potency of the bank lending channel. Furthermore, it diminishes the risk-taking channel of monetary policy within the limit established by macroprudential FX regulations

LATAM Intelligent Filter for Education (LIFE)

The LIFE system is designed to inspire primary-aged students in Latin American schools to pursue higher education in STEM related fields. We hope the students educate others in their community about the public health implications stemming from the lack of clean water and grow to bring about more lasting solutions to the water crisis. Many family’s lives are stymied by the inability to access clean drinking water, with many students ending up spending hours carrying water or spending time recovering water themselves in lieu of attending school. The LIFE team created a tabletop water filter and pump system accompanied by an app that will act as an educational tool for ten Latin American schools, with more on the horizon. This project was designed with both the needs of the teachers and students in mind but also frugality and ease of use by a wide variety of peri urban and urban communities as well as other quantifiable design metrics. The LIFE system is made up of two parts, the Intelligent Filter and the app. The water filter is designed to remove the top contaminants of our target audience: lead, arsenic, nitrates, fecal contamination (E. coli, Salmonella, etc.), and pesticides. The app is complete with full learning modules and interactive components to engage with the students and guides for teachers. The project was successful at a local school test and approved by our clients at the PASSAGE project and Frugal Innovation Hub. It will be replicated in the near future to be distributed to the different communities by our client, PASSAGE