Bienestar familiar y relaciones de amistad. Un estudio con adolescentes en el contexto escolar

El objetivo de este estudio es examinar la relación entre el clima familiar y las relaciones de amistad en el contexto escolar de una muestra de adolescentes. Se ha aplicado una batería procedente de un instrumento estandarizado (TAMAI) y una versión completa del test sociométrico a una muestra de 44 adolescentes de 4º de ESO. El estudio pone de manifiesto que los alumnos satisfechos con el clima familiar reciben más elecciones amistosas y son más populares, poseen una mayor expansividad social positiva, más elecciones mutuas de amistad, mayor vinculación afectiva con su grupo de amigos y mejor estatus sociométrico

La mediación familiar del consumo infantil de televisión. Un análisis referido a la sociedad española

Apoyado en una encuesta realizada por el Centro de Investigaciones Sociológicas a 1.787 familias españolas (E-2391 CIS), este artículo analiza los estilos de mediación del consumo infantil de televisión a los que estas recurren. Tras realizar un análisis factorial con el que se han extraído las principales estrategias de mediación, se ha aplicado un análisis de conglomerados del que ha surgido una tipología compuesta por familias controladoras- restrictivas, permisivas y orientadoras. Previamente se ha examinado la influencia de diversas variables sociodemográficas, familiares y de equipamiento audiovisual en cada una de las estrategias de mediación. Los resultados permiten adoptar con matizaciones algunas tipologías elaboradas en otros países

Tuning the resistive switching properties of TiO2-x films

We study the electrical characteristics of TiO2-x-based resistive switching devices fabricated with different oxygen/argon flow ratio during the oxide thin film sputtering deposition. Upon minute changes in this fabrication parameter, three qualitatively different device characteristics were accessed in the same system, namely, standard bipolar resistive switching, electroforming-free devices, and devices with multi-step breakdown. We propose that small variations in the oxygen/ argon flow ratio result in relevant changes of the oxygen vacancy concentration, which is the key parameter determining the resistive switching behavior. The coexistence of percolative or non-percolative conductive filaments is also discussed. Finally, the hypothesis is verified by means of the temperature dependence of the devices in low resistance state.Fil: Ghenzi, Néstor. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. CIC nanoGUNE; EspañaFil: Rozenberg, M.J.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Física; Argentina. Université Paris Sud; FranciaFil: Llopis, R.. CIC nanoGUNE; EspañaFil: Levy, Pablo Eduardo. Comisión Nacional de Energía Atómica. Gerencia del Área Investigaciones y Aplicaciones no Nucleares; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hueso, Luis E.. Universidad del País Vasco; España. Fundación Vasca para la Ciencia; EspañaFil: Stoliar, Pablo Alberto. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. CIC nanoGUNE; Españ

HCFC-22 replacement with drop-in and retrofit HFC refrigerants in a two-stage refrigeration plant for low temperature

[EN] The world community has committed to eliminate the HCFC-22 refrigerant to a series of deadlines according to the agreements taken during the 19th Montreal Protocol meeting in September 2007. This phase-out, which is already in progress in European Countries, has been accelerated in Article 5 countries. Refrigerant manufactures offer different drop-in refrigerants to replace R22 in existing equipment by non-ozone depleting substances in order to be able to make full use of the remaining life of the plants or different retrofit refrigerants, the use of which implies modifications to the existing systems. This work aims to contribute to the understanding of the implications of the process of R22 substitution, either with drop-in or retrofitting processes, by presenting a theoretical and experimental analysis of the performance of R22, of two drop-in fluids (R422A, R417B) and a retrofit refrigerant (R404A), in a two-stage vapour compression plant over a wide range of evaporating temperatures for a fixed condensing temperature of 40 C. In this communication the main energy parameters, such as cooling capacity and COP are analysed and discussed.The authors are indebted to the Spanish Ministry of Education and Science (CTM2008-06468-CO2-02/TECNO) and to the Spanish Ministry of the Environment and Rural and Marine Affairs (200800050084716) for their economic support for the present work.Llopis, R.; Torrella Alcaraz, E.; Cabello, R.; Sanchez, D. (2012). HCFC-22 replacement with drop-in and retrofit HFC refrigerants in a two-stage refrigeration plant for low temperature. International Journal of Refrigeration. 35(4):810-816. https://doi.org/10.1016/j.ijrefrig.2012.01.001S81081635

Wide-Field Multi-Parameter FLIM: Long-Term Minimal Invasive Observation of Proteins in Living Cells.

Time-domain Fluorescence Lifetime Imaging Microscopy (FLIM) is a remarkable tool to monitor the dynamics of fluorophore-tagged protein domains inside living cells. We propose a Wide-Field Multi-Parameter FLIM method (WFMP-FLIM) aimed to monitor continuously living cells under minimum light intensity at a given illumination energy dose. A powerful data analysis technique applied to the WFMP-FLIM data sets allows to optimize the estimation accuracy of physical parameters at very low fluorescence signal levels approaching the lower bound theoretical limit. We demonstrate the efficiency of WFMP-FLIM by presenting two independent and relevant long-term experiments in cell biology: 1) FRET analysis of simultaneously recorded donor and acceptor fluorescence in living HeLa cells and 2) tracking of mitochondrial transport combined with fluorescence lifetime analysis in neuronal processes

A dynamic mathematical model of a shell-and-tube evaporator. Validation with pure and blend refrigerants

[EN] This work presents a mathematical model of a shell-and-tube evaporator based on mass continuity, energy conservation and heat transfer physical fundamentals. The model is formulated as a control volume combination that represents the different refrigerant states along the evaporator. Since the model is based on refrigerant and secondary fluid states prediction, it can be easily adapted for modelling any type of evaporator. The strategy of working with physical fundamentals allows the steady- and dynamic-state analysis of any of its performance variables. The paper presents a steady-state validation made with two pure refrigerants (HCFC-22, HFC-134a) and with a zeotropic blend (HFC-407C), and a dynamic validation with transient experimental tests using HCFC-22. The model prediction error is lower than 5% and it is well in accordance with actual dynamic behaviour.Llopis, R.; Cabello, R.; Navarro-Esbrí, J.; Torrella Alcaraz, E. (2007). A dynamic mathematical model of a shell-and-tube evaporator. Validation with pure and blend refrigerants. International Journal of Energy Research. 31(3):232-244. doi:10.1002/er.1243S23224431

Second law analysis of two-stage vapour compression refrigeration plants

[EN] This paper describes a Second Law Analysis based on experimental data of a two-stage vapour compression facility driven by a compound compressor for medium and low-capacity refrigeration applications, which operates with the most usual inter-stage configurations (direct liquid injection and subcooler). The experimental analysis is performed for an evaporating temperature range between 36 degrees C and 20 degrees C and for a condensing temperature range between 30 degrees C and 47 degrees C using the refrigerant R-404A. The final results are compared with energy analysis from previous works. Additionally, a new criterion of equivalence between the simple vapour compression cycle and the two-stage compression cycle is given.The authors are indebted to the Spanish Ministry of Education and Science (CTM2008-06468-C02-02/TECNO) and to the Spanish Ministry of the Environment and Rural and Marine Affairs (200800050084716) for their economic support to this work.Torrella Alcaraz, E.; Llopis, R.; Cabello, R.; Sanchez, D.; Larumbe, J. (2010). Second law analysis of two-stage vapour compression refrigeration plants. International Journal of Exergy. 7(6):641-653. https://doi.org/10.1504/IJEX.2010.035512S6416537

In situ electrical characterization of palladium-based single electron transistors made by electromigration technique

We report the fabrication of single electron transistors (SETs) by feedback-controlled electromigration of palladium and palladium-nickel alloy nanowires. We have optimized a gradual electromigration process for obtaining devices consisting of three terminals (source, drain and gate electrodes), which are capacitively coupled to a metallic cluster of nanometric dimensions. This metal nanocluster forms into the inter-electrode channel during the electromigration process and constitutes the active element of each device, acting as a quantum dot that rules the electron flow between source and drain electrodes. The charge transport of the as-fabricated devices shows Coulomb blockade characteristics and the source to drain conductance can be modulated by electrostatic gating. We have thus achieved the fabrication and in situ measurement of palladium-based SETs inside a liquid helium cryostat chamber.Fil: Arzubiaga, L.. CIC nanoGUNE; EspañaFil: Golmar, Federico. Universidad Nacional de San Martín. Escuela de Ciencia y Tecnología; Argentina. Instituto Nacional de Tecnología Industrial; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Llopis, R.. CIC nanoGUNE; EspañaFil: Casanova, F.. CIC nanoGUNE; España. IKERBASQUE; EspañaFil: Hueso, Luis E.. CIC nanoGUNE; España. IKERBASQUE; Españ