Empoderar: nuevo concepto de liderazgo para el administrador educativo

En este artículo se realiza un análisis de las dosdirectrices enviadas por el Dr. Claudio Gutierrez cuandofue Ministro de Educación, en las que se empoderaba alas direcciones regionales de educación y se ponía en prác-tica el principio de subsidiaridad, para establecer unanueva manera de relacionar las direcciones regionalescon las oficinas centrales del Ministerio y éstas con las Ins-tituciones Educativas. Se enfatiza en el potencial de esteconcepto de liderazgo con el objeto de analizar el estadoactual del proceso de empoderamiento en la DirecciónRegional de Alajuela, visto este como un continuo entre laautonomía y el control en los estilos de liderazgo practica-do por los directores cinco del circuito 0

Élites y restricciones institucionales de las reformas agrarias: La implementación del acuerdo de paz en Colombia

El Acuerdo de Paz suscrito entre el gobierno colombiano y la guerrilla de las FARC incluyó un punto sobre el tema agrario denominado Reforma Rural Integral (RRI). En particular, la RRI incluye mecanismos típicos de reformas agrarias dirigidas a otorgar acceso a tierra a campesinos que no cuentan con ella, mediante diversos mecanismos redistributivos o de otro tipo. La información disponible sobre el grado de implementación de las disposiciones de este punto muestra que en gran medida ha sido mínima o inexistente la puesta en marcha de esos mecanismos ¿Cuáles son las causas de estos bloqueos en la implementación de la reforma agraria de la RRI? A partir de la teoría sobre las reformas agrarias redistributivas y por medio del análisis documental, se muestra que los bloqueos obedecen a un caso típico de ausencia de división coalicional entre las élites políticas y élites terratenientes, junto a un contexto de altas restricciones institucionales. Así mismo, se evidencia que estos bloqueos se manifiestan en los obstáculos para adoptar la legislación necesaria para dar base a la RRI y a una disminución del presupuesto destinado a la burocracia encargada de implementar mecanismos de redistribución, negociación y colonización de tierras

Structure and dynamics in liquid iron at high pressure and temperature. A first principles study

Producción CientíficaWe have studied the evolution of structural and dynamic properties of liquid Fe as a function of pressure for 11 thermodynamic states close to the melting line. The pressure range considered goes from ambient pressure to 323 GPa, and the study has been carried out by using the ab-initio molecular dynamics technique. The agreement between the calculated static structure and the available experimental data is very good, including details like an asymmetric second peak, which remains over most of the whole pressure range and suggests a significant local icosahedral short-range order in the liquid. The dynamical structure is studied through the characteristics of the propagating density fluctuations and the associated longitudinal and transverse particle currents. The transverse dispersion relations expose two branches of modes for all pressures, whose range of appearance is analyzed and put in connection with the double-peak structure of the Fourier spectra of velocity autocorrelation functions. We have also investigated the existence of fingerprints of transverse acoustic excitation modes in the dynamic structure factor for the high pressure states similar to those observed in the inelastic X-ray scattering intensity data of liquid Fe at ambient pressure. The calculated electronic density of states shows that with increasing pressure there is a widening of the conduction band along with a decreasing significance of spin polarization. Finally, we also report results for transport coefficients like self-diffusion, shear viscosity and adiabatic sound velocity, which are compared with the available experimental data.Ministerio de Economía y Competitividad junto con el Fondo Europeo de Desarrollo Regional (Project PGC2018-093745-B-I00

Quantitative Assessment of Mycoplasma Hemadsorption Activity by Flow Cytometry

A number of adherent mycoplasmas have developed highly complex polar structures that are involved in diverse aspects of the biology of these microorganisms and play a key role as virulence factors by promoting adhesion to host cells in the first stages of infection. Attachment activity of mycoplasma cells has been traditionally investigated by determining their hemadsorption ability to red blood cells and it is a distinctive trait widely examined when characterizing the different mycoplasma species. Despite the fact that protocols to qualitatively determine the hemadsorption or hemagglutination of mycoplasmas are straightforward, current methods when investigating hemadsorption at the quantitative level are expensive and poorly reproducible. By using flow cytometry, we have developed a procedure to quantify rapidly and accurately the hemadsorption activity of mycoplasmas in the presence of SYBR Green I, a vital fluorochrome that stains nucleic acids, allowing to resolve erythrocyte and mycoplasma cells by their different size and fluorescence. This method is very reproducible and permits the kinetic analysis of the obtained data and a precise hemadsorption quantification based on standard binding parameters such as the dissociation constant Kd. The procedure we developed could be easily implemented in a standardized assay to test the hemadsorption activity of the growing number of clinical isolates and mutant strains of different mycoplasma species, providing valuable data about the virulence of these microorganisms

Análisis de la rentabilidad en el sector de la distribución en Europa

This empine study aims at stablishing which are the main factors that explain profitability in companies operating in the european distribution sector and their reiative importance. Methodology is based on an analysis of variance and its components. Although this type of analysis has been frequently applied on the industrial sector, its use in the distribution business is very innovative, above all when we consider the country as one of the key factors.Au travers de ce travail empirique on veut analyser quels sont les facteurs qui expliquent la rentabilité des entreprises dans le secteur de la distribution en Europe. On veut également connaftre l'importance reiative de chacun de ees facteurs. La méthodologie employée a été l'Analyse de la Variance et lAnalyse des Composants de la Variance. Mime si ce type d'analyse a été appliquée avec une fréquence reiative dans quelques secteurs industriéis, dans celui de la distribution c'est nouveau, surtout si on prend en compte le pays comme facteur explicati

Multiple Order Dual-Band Active Ring Filters with Composite Right/Left Handed Cells

In this paper, a novel dual-band active filter topology is presented. The non-linear phase response of a composite right/left-handed cell is used to achieve the desired dual-band performance. Additionally, the proposed structure based on coupled ring resonators yields a very compact solution in which high-order implementations can be easily obtained by cascading multiple rings. The theoretical principles of this type of filters are analyzed in detail. Finally, three prototypes based on first-, second- and third-order structures validate the feasibility of this type of filters. Good agreement between simulations and measurements has been achieved

First principles study of liquid uranium at temperatures up to 2050 K

Producción CientíficaUranium compounds are used as fissile materials in nuclear reactors. In present day reactors the most used nuclear fuel is uranium dioxide, but in generation-IV reactors other compounds are also being considered, such as uranium carbide and uranium mononitride. Upon possible accidents where the coolant would not circulate or be lost the core of the reactor would reach very high temperatures, and therefore it is essential to understand the behaviour of the nuclear fuel under such conditions for proper risk assessment. We consider here molten metallic uranium at several temperatures ranging from 1455 to 2050 K. Even though metallic uranium is not a candidate for nuclear fuel it could nevertheless be produced due to the thermochemical instability of uranium nitride at high temperatures. We use first principles techniques to analyse the behaviour of this system and obtain basic structural and dynamic properties, as well as some thermodynamic and transport properties, including atomic diffusion and viscosity.Junta de Castilla y León (Ref. project VA124G18)Ministerio de Economía, Industria y Competitividad (Project PGC2018-093745-B-I00) and FEDE

Noise Figure Measurement of Differential Amplifiers Using non-Ideal Baluns

This paper analyzes the noise and gain measurement of microwave differential amplifiers using two passive baluns. A general model of the baluns is considered, including potential losses and phase/amplitude unbalances. This analysis allows de-embedding the actual gain and noise performance of the isolated amplifier by using single-ended measurements of the cascaded system and baluns. Finally, measured results from two amplifier prototypes are used to validate the theoretical principles