Decoherence of Einstein-Podolsky-Rosen steering

We consider two systems A and B that share Einstein-Podolsky-Rosen (EPR) steering correlations and study how these correlations will decay, when each of the systems are independently coupled to a reservoir. EPR steering is a directional form of entanglement, and the measure of steering can change depending on whether the system A is steered by B, or vice versa. First, we examine the decay of the steering correlations of the two-mode squeezed state. We find that if the system B is coupled to a reservoir, then the decoherence of the steering of A by B is particularly marked, to the extent that there is a sudden death of steering after a finite time. We find a different directional effect, if the reservoirs are thermally excited. Second, we study the decoherence of the steering of a Schr\"odinger cat state, modeled as the entangled state of a spin and harmonic oscillator, when the macroscopic system (the cat) is coupled to a reservoir

Una nueva estrategia para el estudio de la vulnerabilidad de edificios expuestos a explosiones a cielo abierto

ResumenEn este artículo se describe una nueva metodología para evaluar el efecto de las explosiones a cielo abierto sobre estructuras equivalentes a las fachadas de los edificios. El daño sufrido por la estructura se define mediante superficies de vulnerabilidad que son función de la magnitud de la explosión, la distancia de esta a la estructura y del índice de daño por detonación desarrollado en este artículo. El índice propuesto considera la degradación de la capacidad de carga de la estructura, la fracturación y la perdida de material debido a la explosión. Para ello, la estructura se modela mediante elementos discretos (DEM) los cuales permiten representar adecuadamente estados de multifractura. La capacidad de carga de la estructura se cuantifica mediante un ensayo virtual sobre la estructura dañada. Las fuerzas provocadas sobre la estructura por la explosión se modelan utilizando una metodología semiempírica, lo que permite obviar el análisis con base en la dinámica de fluidos reduciendo el tiempo de cálculo.AbstractIn this paper, a new methodology is described to evaluate the effect of open air explosions on equivalent structures to the facades of buildings. The structural damage is defined by vulnerability surfaces that are a function of the explosion magnitude, the distance to the structure and the detonation damage index developed in this article. The proposed index considers the structural load capacity degradation, the fracturing and the loss material due to the explosion. The structure is modeled by means of discrete elements (DEM) which allows describing the multifracturing state. The load capacity of the structure is quantified by a virtual compression test on the damaged structure. The forces on the structure caused by the explosion are modeled by a semi-empirical methodology, which avoids the fluid-dynamic analysis and reduces the computation time

EL AHORRO DE LOS HOGARES EN COLOMBIA

En este documento se presenta un análisis del comportamiento del ahorro de los hogares y sus determinantes, considerando una perspectiva de largo plazo para el periodo 1950-2004 y una de corto plazo a nivel microeconómico, utilizando la información de las encuestas de calidad de vida de 1997 y 2003. A nivel agregado, con base en un análisis de cointegración se encontró una relación de largo plazo entre la tasa de ahorro de los hogares, el PIB per-cápita, los impuestos directos y una medida de profundización financiera. A nivel microeconómico, se realiza un análisis de las tasas de ahorro agrupadas por diferentes características socioeconómicas de los hogares y para diferentes definiciones de ahorro considerando la inversión en capital humano y la compra de bienes durables. Adicionalmente, se presenta un análisis del comportamiento del ahorro a partir de la hipótesis del ciclo de vida, utilizado los perfiles de ahorro por año de nacimiento del jefe del hogar. Los resultados muestran que tanto el ingreso como el consumo registran un comportamiento de U invertida, sugiriendo que para el caso Colombiano no hay evidencia de que se cumpla la hipótesis del ciclo de vida. Finalmente, al comparar los datos de ahorro de los hogares a nivel agregado, con los datos obtenidos a partir de la información de las encuestas se encuentran diferencias que se pueden explicar por razones metodológicas y por el cambio en la distribución de los ingresos y de los gastos registrado entre 1997 y 2003.Ahorro de los hogares, hipótesis de ciclo de vida, consumo, Colombia. Classification JEL:D12; D19; E01; E21.

A new strategy for the vulnerability study of buildings exposed to open-airexplosions

En este artículo se describe una nueva metodología para evaluar el efecto de las explosiones a cielo abierto sobre estructuras equivalentes a las fachadas de los edificios. El daño sufrido por la estructura se define mediante superficies de vulnerabilidad que son función de la magnitud de la explosión, la distancia de esta a la estructura y del índice de daño por detonación desarrollado en este artículo. El índice propuesto considera la degradación de la capacidad de carga de la estructura, la fracturación y la perdida de material debido a la explosión. Para ello, la estructura se modela mediante elementos discretos (DEM) los cuales permiten representar adecuadamente estados de multifractura. La capacidad de carga de la estructura se cuantifica mediante un ensayo virtual sobre la estructura dañada. Las fuerzas provocadas sobre la estructura por la explosión se modelan utilizando una metodología semiempírica, lo que permite obviar el análisis con base en la dinámica de fluidos reduciendo el tiempo de cálculo.In this paper, a new methodology is described to evaluate the effect of open air explosions on equivalent structures to the facades of buildings. The structural damage is defined by vulnerability surfaces that are a function of the explosion magnitude, the distance to the structure and the detonation damage index developed in this article. The proposed index considers the structural load capacity degradation, the fracturing and the loss material due to the explosion. The structure is modeled by means of discrete elements (DEM) which allows describing the multifracturing state. The load capacity of the structure is quantified by a virtual compression test on the damaged structure. The forces on the structure caused by the explosion are modeled by a semi-empirical methodology, which avoids the fluid-dynamic analysis and reduces the computation time.Peer Reviewe

Multi-tenant slicing for spectrum management on the road to 5G

©2017 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The explosive data traffic demand in the context of the 5G revolution has stressed the need for network capacity increase. As the network densification has almost reached its limits, mobile network operators are motivated to share their network infrastructure and the available resources through dynamic spectrum management. Although some initial efforts have been made in this direction by concluding sharing agreements at a coarse granularity (i.e., months or years), the 5G developments require fine timescale agreements, mainly enabled by network slicing. In this article, taking into account the radical changes foreseen for next generation networks, we provide a thorough discussion of the challenges that network slicing brings in the different network parts, while introducing a new entity capable of managing the end-to-end slicing in a coherent manner. In addition, according to the paradigm shift of operators sharing their resources in a common centralized pool, we design a cooperative game to study the potential cooperation aspects among the participants. The experimental results highlight the performance and financial gains achievable by operators through multi-tenant slicing, providing them with the necessary incentives for network upgrade toward 5G.Peer ReviewedPostprint (author's final draft

Accelerated detectors in Dirac vacuum: the effects of horizon fluctuations

We consider an Unruh-DeWitt detector interacting with a massless Dirac field. Assuming that the detector is moving along an hyperbolic trajectory, we modeled the effects of fluctuations in the event horizon using a Dirac equation with random coefficients. First, we develop the perturbation theory for the fermionic field in a random media. Further we evaluate corrections due to the randomness in the response function associated to different model detectors.Comment: 19 pages, 1 figur

Sequential Effects in Judgements of Attractiveness: The Influences of Face Race and Sex

In perceptual decision-making, a person’s response on a given trial is influenced by their response on the immediately preceding trial. This sequential effect was initially demonstrated in psychophysical tasks, but has now been found in more complex, real-world judgements. The similarity of the current and previous stimuli determines the nature of the effect, with more similar items producing assimilation in judgements, while less similarity can cause a contrast effect. Previous research found assimilation in ratings of facial attractiveness, and here, we investigated whether this effect is influenced by the social categories of the faces presented. Over three experiments, participants rated the attractiveness of own- (White) and other-race (Chinese) faces of both sexes that appeared successively. Through blocking trials by race (Experiment 1), sex (Experiment 2), or both dimensions (Experiment 3), we could examine how sequential judgements were altered by the salience of different social categories in face sequences. For sequences that varied in sex alone, own-race faces showed significantly less opposite-sex assimilation (male and female faces perceived as dissimilar), while other-race faces showed equal assimilation for opposite- and same-sex sequences (male and female faces were not differentiated). For sequences that varied in race alone, categorisation by race resulted in no opposite-race assimilation for either sex of face (White and Chinese faces perceived as dissimilar). For sequences that varied in both race and sex, same-category assimilation was significantly greater than opposite-category. Our results suggest that the race of a face represents a superordinate category relative to sex. These findings demonstrate the importance of social categories when considering sequential judgements of faces, and also highlight a novel approach for investigating how multiple social dimensions interact during decision-making