Chip level simulation of the downlink in UTRA-FDD

The specifications of UMTS Terrestrial Radio Access (UTRA) for the physical layer of the downlink make use of orthogonal variable spreading factor (OVSF) codes to preserve the orthogonality between downlink channels of different rates and spreading factors. This technique minimises the downlink intra-cell interference. In order to control the inter-cell interference, every base station multiplies the global downlink signal with a cell specific Gold code (scrambling code). Then, while the inter-cell interference may be modelled using the Gaussian hypothesis (that is: replacing the real interference with a Gaussian noise of the same power), the intra-cell interference requires detailed chip level simulations. In this paper we present results of a chip level simulation of the downlink UTRA physical layer. The objective is to evaluate the raw (uncoded) mean bit error rate (BER) of the system in a realistic environment and conditions. Then, by knowing the BER requirements of the different services, one can easily obtain the maximum capacity in terms of simultaneous connections at any combination of bit rates.Peer ReviewedPostprint (published version

Latin America’s Seven Mortal Sins: Myth, Reality and Consequences

The heavy investments of important Spanish companies in Latin America in recent years have significantly increased Spain’s concern with the region’s macroeconomic developments. Unfortunately, most analyses of the region’s complex social and economic realities have unrealistically attempted to offer a brief yet conclusive evaluation of Latin America in its entirety, feeding one or another preconceived generalization, depending on the political agenda of the author in question. Indeed, either “Latin America is the region of the future” or it is a place that will continue to be so for a long time to come

Robust DEA efficiency scores: A probabilistic/combinatorial approach

In this paper we propose robust efficiency scores for the scenario in which the specification of the inputs/outputs to be included in the DEA model is modelled with a probability distribution. This proba- bilistic approach allows us to obtain three different robust efficiency scores: the Conditional Expected Score, the Unconditional Expected Score and the Expected score under the assumption of Maximum Entropy principle. The calculation of the three efficiency scores involves the resolution of an exponential number of linear problems. The algorithm presented in this paper allows to solve over 200 millions of linear problems in an affordable time when considering up 20 inputs/outputs and 200 DMUs. The approach proposed is illustrated with an application to the assessment of professional tennis players

Inmigrantes empresarios

Este artículo es el resumen de una investigación, a través de Entrevistas en Profundidad y de Historias de Vida, que ha tratado de indagar quienes son desde el punto de vista sociológico los inmigrantes que han creado una empresa en la Comunidad de Madrid, abordando la comprensión de los comportamientos y las relaciones sociales en las que están inmersos, alejándonos de una visión meramente cuantitativa y economicista. Hay que abordar, pues, el fenómeno de la inmigración como una cuestión política ya que ha adquirido un significado político radical, perteneciendo al núcleo mismo de ésta y no a su periferia, constituyéndose en un desafió para reflexionar sobre las condiciones del vínculo social y del contrato político, con el consiguiente cambio de la noción de lo que es la soberanía y la ciudadanía.This paper sums up the results of a research based on interviews in depth and daily life stories of immigrants within the Community of Madrid that have set up a business. Special attention is paid to their behaviour and the social relations in which they are immersed, avoiding a mere quantitative and economist interpretation. On the contrary, immigration is explained as a political issue due to the fact that it became an important radical argument of politics that claims for some reflections referring to the conditions of social cohesion and political contract in order to redefine the concept of sovereignty and citizenship

Adsorción selectiva de mezclas etanol-butanol-acetona en fase líquida

En la presente investigación se ha estudiado la adsorción de las mezclas acuosas de etanol, butanol, acetona y glucosa sobre carbón activado y tamices moleculares de diferentes relaciones si/al. Con objeto de seleccionar un absorbente apropiado para la separación de etanol de mezclas acuosas diluidas en presencia de otros adsorbatos (glucosa), se obtuvieron las isotermas experimentales de equilibrio en un intervalo de temperaturas de 25 a 55 grados c. De este estudio se eligió la silicalita como absorbente. Asimismo, se han determinado las isotermas experimentales de mezclas binarias y ternarias del sistema etanol-butanol-acetona, así como las correspondientes curvas de rotura de lecho fijo. Las isotermas individuales de los absorbentes empleados se ajustaron a las ecuaciones de langmuir, freundlich y prausnitz, siendo esta última la que proporcionaba un mejor ajuste de los datos experimentales. Se han realizado la predicción teórica de las isotermas de equilibrio de mezclas binarias, mediante el modelo de la solución adsorbida ideal (s.a.i.) aplicándose el modelo de la solución absorbida real (s.a.r.) para la reproducción de los mismos sistemas binarios. El s.a.r. es el modelo que mejor ajustaba los sistemas binarios estudiados. Por último se desarrolló un modelo matemático simplificado, basado en el coeficiente global de transferencia de materia, para la simulación de la adsorción en lecho fijo, para la silicalita o silicalita aglomerada, como absorbentes. En todos los casos, los valores experimentales se reprodujeron con un error inferior al 15%

The freedom of movement of asylum-seekers within the host State under international and European human rights law

Asylum-seekers in several European States often have to endure policies that make them feel trapped in a specific part of the country or that constrain their movements to such an extent that their situation resembles detention. How can human rights law respond to these practices? This PhD thesis comprehensively examines the right to free movement within the country under international and European human rights law, as well as under the Spanish and German domestic legal systems. With a specific focus on asylum-seekers, the study analyses this issue from four different angles: (1) the travaux préparatoires of the various instruments that enshrine this freedom; (2) the personal scope of the right according to legal doctrine and case law; (3) the material scope of the right, i.e. the distinction between a restriction on movement and a deprivation of liberty; and (4) the safeguards offered by this right. By comparing the protection afforded to asylum-seekers with that extended to nationals and individuals in general, the thesis contributes to the growing literature on migration exceptionalism. Additionally, the exploration of the legal status of asylum-seekers under various treaties and the detailed assessment of the definition of ‘detention’ hold the potential to inform research in other areas of human rights law, including refugee law

Differential Galois Theory and Quantum Physics (Recent Developments in Dynamical Systems and their Applications)

We survey my 2020 paper [18], on the relevance of the differential Galois theory of linear differential equations for the exact semiclassical computations in path integrals in quantum mechanics. The main tool will be a necessary condition for complete integrability of classical Hamiltonian systems obtained by Ramis and myself, formulated in the framework of differential Galois theory. A corollary of this result is that, for finite dimensional integrable Hamiltonian systems, the semiclassical approach is computable in closed form. This explains in a very precise way the success of quantum semiclassical computations for integrable Hamiltonian systems. Moreover, I will point out several of the many open problems motivated from the above simple result: problems from quantum mechanics to quantum field theory

The concept of finite limit of a function at one point as explained by students of non-compulsory secondary education

We review various educational studies of the mathematical concept of limit of a function at a point that indicate how colloquial uses of the terms “to approach,” “to tend toward,” “to reach,” “to exceed” and “limit” influence students’ conceptions of these terms. We then present the results of an exploratory study of this question performed with Spanish students in non-compulsory secondary education and analyze the responses they provide to justify the truth or falsity of statements related to the different characteristics of the concept of finite limit of a function at a point when they use these terms. Finally, we organize their answers according to the kinds of arguments made. Using the response profiles detected, we discuss the influence of everyday usage on the students’ arguments