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

Hallazgos en ecografía de mama en pacientes del Centro de Salud El Porvenir - Lima 2021

Objetivo: Determinar cuáles son las características más frecuentes de las lesiones mamarias diagnosticada por ecografía en las pacientes del Centro de Salud Materno Infantil El Porvenir durante el año 2021. Método: La investigación fue descriptiva, con un enfoque cuantitativo, retrospectivo, de corte transversal y de tipo no experimental. La muestra estuvo conformada por 132 informes ecográficos del Centro de Salud Materno Infantil El Porvenir durante el año 2021. Resultados: La edad promedio en las pacientes que formaron parte del estudio fue de 42,4 ± 14 años. La ubicación más frecuente de las lesiones mamarias según la mama afectada, fueron las lesiones bilaterales (37,12%), seguido de las lesiones en la mama izquierda (35.61%) y finalmente la mama derecha (27.27%). La ubicación más frecuente fue el cuadrante superior externo, en el que se encontró el 52,2% del total de lesiones mamarias. La lesión mamaría más frecuente fueron los quistes simples, presentes en el 50,5% de pacientes, seguido de los fibroadenomas que estuvo presente en el 27,4% de pacientes. Conclusiones: Se concluye que la ecografía es una técnica útil para diagnosticar y clasificar las lesiones mamarias

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