The fluid mechanics of bubbly drinks

Bubbly drinks are surprisingly attractive. There is something about the nature of the these beverages that make them preferable among other choices. In this article we explore the physics involved in this particular kind of two-phase, mass-transfer-driven flows.Comment: Extended version of Zenit R and Rodr\'iguez-Rodr\'iguez J. The fluid mechanics of bubbly drinks. Physics Today, Vol. 71(11) pp. 44-50, November 201

Estimation of the modulation index of cpm signals using hos

Three simple methods are proposed for the estimation of the modulation index of continuous phase modulated signals in noise. These methods employ the estimated autocorrelation and fourth-order cumulant sequences of the received signal after sampling at the symbol rate. Analytic expressions are derived for the asymptotic mean and variance of the estimated parameters which are corroborated by means of Monte Carlo simulations. The performance of the methods is illustrated graphically and numerically. It is concluded that, under significant noise degradation, only the scheme based on the fourth-order cumulant sequence can be used to estimate consistently the modulation index h in the range 0(h(1.Peer ReviewedPostprint (published version

Banking on Democracy: The Political Economy of International Private Bank Lending in Emerging Markets

Clearly, a new agenda is emerging for private international banks. Political issues such as human rights seem to be a current concern. But what about democracy? What about political regimes? Are they taken into account by private banks when they decide whether to invest in a country? Put another way, do private banks have democratic political preferences? In this article, we focus on cross-border lending from international bank(er)s. The questions asked are as follows. Do bank(er)s react positively (that is by increasing their lending) when an emerging democracy appears? Do we witness increased bank lending after democratic transitions? Lastly, is there any relation between democratic consolidation and bank lending?Banks;Capital flows;Democracy;Emerging markets

El universitario con discapacidad

Ponencias de las Terceras Jornadas sobre Empleo y Discapacidad celebradas el 29 de abril de 2009 en la Universidad Carlos III de MadridNo publicad

Ciudad Biótica: Chapinero, Bogotá

Trabajo de gradoEste documento contiene una descripción de la localización, aspectos físicos, geográficos, evaluación de diferentes aspectos, Con el ánimo de proponer un proyecto que contemple todas las variables del entorno para reforzar su identidad propia, se presentan estadísticas y una evaluación de la situación de seguridad, criminalidad y violencia que se registra en la localidad, por lo anterior se propone un proyecto de vivienda para la localidad de Chapinero.PregradoArquitect

Blind multiuser detection using hidden markov models theory

We present an adaptive algorithm based on the theory of hidden Markov models (HMM) which is capable of jointly detecting the users in a DS-CDMA system. The proposed technique is near-far resistant and completely blind in the sense that no knowledge of the signature sequences, channel state information or training sequences is required for any user. In addition to this, an estimate of the signature of each user convolved with its physical channel impulse response (CIR), and an estimate of the background noise variance are provided once convergence is achieved (as well as estimated data sequences). At this moment, and using that CIR estimate, we can switch to any decision-directed (DD) adaptation scheme.Peer ReviewedPostprint (published version

Array joint detection for C/TDMA systems in UMTS environments

Two array-based schemes for intracell and intercell interference suppression are proposed. In both cases, the spatial and temporal characteristics of the propagation are jointly exploited by placing a narrowband beamformer prior to the corresponding data detection stage. In the first approach, the filtered training sequence joint detection receiver (FTS-JDR), the beamformer is devoted to exclusively cancel out intercell interference. This way, intracell users can be jointly detected in a MMSE detection block. In contrast, the second algorithm, known as the filtered training sequence multisensor receiver (FTS-MR), aims to attenuate all the interferers in the beamforming stage which allows the user of interest to be detected following a MLSE strategy. In order to assess the performance of the proposed schemes, a set of link-level computer simulations adopting FRAMES' proposal for UMTS air-interface as well as realistic channel models for third generation communication systems is provided. Simulation results indicate that lower BERs can be obtained by concentrating interference cancellation tasks in the beamforming block.Peer ReviewedPostprint (published version

Application of hidden markov models to blind channel estimation and data detection in a gsm environment

In this paper, we present an algorithm based on the Hidden Markov Models (HMM) theory to solve the problem of blind channel estimation and sequence detection in mobile digital communications. The environment in which the algorithm is tested is the Paneuropean Mobile Radio System, also known as GSM. In this system, a large part in each burst is devoted to allocate a training sequence used to obtain a channel estimate. The algorithm presented would not require this sequence, and that would imply an increase of the system capacity. Performance, evaluated for standard test channels, is close to that of non-blind algorithms.Peer ReviewedPostprint (published version