Quantum localized states in photonic flat-band lattices

The localization of light in flat-band lattices has been recently proposed and experimentally demonstrated in several configurations, assuming a classical description of light. Here, we study the problem of light localization in the quantum regime. We focus on quasi one-dimensional and two-dimensional lattices which exhibit a perfect flat-band inside their linear spectrum. Localized quantum states are constructed as eigenstates of the interaction Hamiltonian with a vanishing eigenvalue and a well defined total photon number. These are superpositions of Fock states with probability amplitudes given by positive as well as negative square roots of multinomial coefficients. The classical picture can be recovered by considering poissonian superpositions of localized quantum states with different total photon number. We also study the separability properties of flat band quantum states and apply them to the transmission of information via multi-core fibers, where these states allow for the total passive suppression of photon crosstalk and exhibit robustness against photon losses. At the end, we propose a novel on-chip setup for the experimental preparation of localized quantum states of light for any number of photons.Comment: 12 pages, 5 figure

Cuando la cultura se convierte en política

La reflexión que he escrito para esta ocasión trata de la relación entre la antropología y la realidad, entre la cultura y la política, entre los pueblos indígenas y el poder. En la primera parte, centro mi atención en los conceptos y en la conversión del objeto de estudio de nuestra disciplina en sujeto, en la extraordinaria transformación del concepto de cultura en política, en la victoria de la diversidad cultural sobre la uniculturalidad del Estado nación, y en la réplica frente a esa victoria desde el poder. En la segunda parte trato de mostrar el proceso de aparición y cambio de las categorías que usamos en Perú para nombrarnos e insultarnos; es decir, de habitantes de América a indios, de indios a campesinos, de campesinos a indígenas. Cierro esta reflexión con una mirada histórica sobre lo que la palabra Perú quiso y quiere decir y sobre el porvenir de la cultura quechua. Mi texto “Con los rostros pintados: tercera rebelión amazónica en Perú (agosto 2008-junio2009)”, (Montoya, 2009) presenta el momento cumbre en el que la cultura se convierte en política. Me parece que este acontecimiento es trascendental en la historia del país y en el desarrollo de nuestra disciplina.The reflection I have written for this journal is about the relationship between anthropology and reality, between culture and politics, between indigenous peoples and power. In the first part, I focus on the concepts and the conversion of the reaearch objects of our discipline into subjects, in the extraordinary transformation of the concept of culture into politics, in the victory of cultural diversity over the uniculturality of the Nation-state, and in the reply of power to that victory. In the second part, I attempt to show the proccess of emergence and change of the categories we use in Perú to name and insult among us; that is, from American inhabitants to indians, from indians to peasants, from indians to natives. I finish this reflection with an historical view on what the word Perú attempted to mean and currently means, and on the future of quechua culture. Mi text “Con los rostros pintados: tercera rebelión amazónica en Perú (agosto 2008-junio2009)”, (Montoya, 2009) llustrates the peak of the process of convertion of culture into politics. It seems to me that this event has far-reaching implications for both the history of the country and the development of our discipline

Leadership distributed as a key factor for the implementation of preventive school mental health programs

El propósito de esta investigación fue indagar los efectos del liderazgo distribuido sobre la implementación de programas escolares preventivos. A través de un diseño cualitativo se aplicaron entrevistas semiestructuradas a 15 involucrados en la supervisión y ejecución del programa Habilidades para la Vida desarrollado en escuelas chilenas. Se encontró que aquellas escuelas en donde se distribuye con mayor institucionalización del liderazgo, a través de dispositivos como reuniones de planificación y evaluaciones continuas, las dimensiones de implementación asociadas a la exposición de la intervención se ejecutan con mayor calidad. Así mismo, la articulación de objetivos entre el programa y la escuela favorece el desarrollo de una cultura escolar en donde se valora el fortalecimiento de habilidades emocionales como condiciones de posibilidad para el anclaje y desarrollo de aprendizajes. Se discuten implicancias teóricas y prácticas sobre este hallazgoThe aim research was to investigate the effects of distributed leadership on the implementation of preventive school programs. Through a qualitative design semistructured interviews were applied to 15 participants, supervisors and professionals of the Skills for Life program in Chilean schools. We were found that those schools where it is distributed with greater institutionalization of leadership, through devices such as planning meetings and continuous evaluations, the implementation dimensions associated with the intervention exposure are executed with higher quality. Likewise, the articulation of objectives between the program and the school favors the development of a school culture where the strengthening of emotional abilities is valued as conditions of possibility for the anchoring and development of learning. Theoretical and practical implications of this finding are discusse

Enhancing organizational performance with social media use: the catalysing effect of corporate entrepreneurship

Social Media use has become pervasive and firms are increasingly relying on it, not only to relate to customers, but also to leverage internal processes like innovation. The strategic use of these tools can facilitate also the entrepreneurial orientation of the firm, as it provides useful knowledge which can make the firm more entrepreneurial, stimulating it to find new opportunities or innovative ideas where other companies do not recognize them. However, despite the relevance of the phenomenon in current hyper-competitive environments, empirical research on the topic remains scarce. To shed some light on the issue, the main purpose of the paper is to examine how Social Media use impacts the different dimensions of corporate entrepreneurship (new business venturing, innovativeness, proactiveness and self-renewal), enhancing also organizational performance. The study is intended to extend knowledge on this topic, by providing understanding of the path firms should take to benefit from Social Media use to become more entrepreneurial and achieve higher organizational performance, developing and nurturing competitive advantages. The paper analyses data obtained from a sample of 201 technological firms located in Spain. The methodology used is Structural equation modelling with LISREL analysis. Findings confirms how the use of Social Media tools positively impacted all the different dimensions of corporate entrepreneurship, translating also in enhanced performance. This paper contributes to the literature by empirically confirming in a structural model how Social Media use helps to create business value, by enhancing proactive behaviours, promoting strategic renewal inside the firm and increasing innovativeness and new business venturing and displaying the internal and sequential relationships among these dimensions.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Análisis del comportamiento de tensiones máximas inducidas en pavimentos rígidos debido al reemplazo parcial de losas

The objective of this study is to analyze the behavior of the maximum stresses induced in concrete slabs as a result of modifications in their geometry. This condition is due to maintenance operations that consider the partial replacement of paving slabs. The analysis is carried out by modeling finite elements of the pavement in sections that consider 2 transversal slabs and 3 longitudinal slabs. A square geometry, traditionally used in Chile, of 3,500 mm (length) x 3,500 mm (width) has been used as the base for each slab. The effect of partial replacement of the central slab by variable lengths in combination with variations in slab thickness of 150 mm, 160 mm, 180 mm and 200 mm has been studied for 3 types of subgrade. The models have been solved by means of finite element analysis and for this the EverFE 2.26 software has been used, which has been widely used for the study of rigid pavements. The maximum stresses induced by the most critical position of the load have been studied, which corresponds to the positioning of the single axle with dual tires on the edge of the slab. The results allow recommending a limit configuration in the partial replacement of slabs in order to control the maximum stresses induced and thereby avoid the reduction of their useful life. The determined increase in the stresses in the slab is between 3.63 and 7.61% and these values allow calculating by fatigue models, a decrease in the total number of load applications of 27% for slab thicknesses of 150mm (K=0.064 MPa/mm) and 14% for slabs of 200mm (K=0.064 MPa/mm) thickness, which is reflected in a reduction in its useful life.El objetivo del presente estudio es analizar el comportamiento de las tensiones máximas inducidas en losas de concreto producto de modificaciones en su geometría. Esta condición se debe a operaciones de mantenimiento que consideran el reemplazo parcial de losas de pavimento. El análisis se realiza mediante la modelación en elementos finitos del pavimento en secciones que consideran 2 losas transversales y 3 losas longitudinales. Se ha utilizado como base una geometría cuadrada, tradicionalmente empleada en Chile, de 3.500 mm (largo) x 3.500 mm (ancho) para cada losa. Se ha estudiado el efecto del reemplazo parcial de la losa central por largos variables en combinación con variaciones en el espesor de la losa de 150 mm, 160 mm, 180 mm y 200 mm para 3 tipos de subrasantes. Los modelos han sido resueltos mediante análisis de elementos finitos y para ello se ha empleado el software EverFE 2.26, que ha sido ampliamente utilizado para el estudio de pavimentos rígidos. Se han estudiado las máximas tensiones inducidas por la posición más crítica de la carga, que corresponde al posicionamiento del eje simple rodado doble en el borde de la losa. Los resultados permiten recomendar una configuración límite en el reemplazo parcial de losas con el fin de controlar las tensiones máximas inducidas y con ello evitar la disminución de su vida útil. El aumento determinado de las tensiones en la losa se encuentra entre 3,63 y 7,61% y dichos valores permiten calcular, mediante modelos de fatiga, una disminución en el número total de repeticiones de carga de 27% para espesores de losas de 150mm (K=0,064 MPa/mm) y de 14% para losas de 200mm (K=0,064 MPa/mm) de espesor, lo que se refleja en una reducción de su vida útil

Synthesis of silicon- and germanium-rich phases at high-pressure conditions

The main focus of the present work was the Ge-rich part of the binary Ba – Ge system, in which by inspecting the behavior of the clathrate-I Ba8Ge43 under pressure, several new phases were found. The new phases in this system have the following compositions: BaGe3 (with two modifications), BaGe5, BaGe5.5 and BaGe6, therefore they are quite close in composition range: 75% - ~85% at. Ge. Concerning the conditions required for the synthesis of each phase, several combinations of temperature and pressure were employed in order to find a stability range. It was possible to establish such a formation range for all phases. In some cases two phases were found for a given conditions and in many other cases three or more phases were found to coexist. Thus, the stability range of pressure and temperature for single phase formation turned out to be very narrow. By inspecting of some structural features, for instance the interatomic distances, it is found that the average of the Ge – Ge distances change in line with the composition, i.e. the shorter contacts belong to BaGe6 while the longer distances are present in BaGe3 (both modification). An opposite trend is observed for the calculated density of each phase (neglecting the tI32 form of BaGe3): the lower density is found for BaGe3 and the denser compound is found to be BaGe6. Of course this is not coincidence, since due to the Ge content, BaGe6 has the largest molar mass. Similarly, by examining the density as a function of the interatomic distance. In such case, the denser compound is characterized by shorter Ge – Ge contacts, while the less dense phase holds the longest Ge – Ge contacts. This is in agreement with the building motifs within each crystal structure: columns in BaGe3 (open framework) passing through layers in BaGe5, ending in a three-dimensional network (closed framework) in BaGe6