Distortion Exponent in MIMO Fading Channels with Time-Varying Source Side Information

Transmission of a Gaussian source over a time-varying multiple-input multiple-output (MIMO) channel is studied under strict delay constraints. Availability of a correlated side information at the receiver is assumed, whose quality, i.e., correlation with the source signal, also varies over time. A block-fading model is considered for the states of the time-varying channel and the time-varying side information; and perfect state information at the receiver is assumed, while the transmitter knows only the statistics. The high SNR performance, characterized by the \textit{distortion exponent}, is studied for this joint source-channel coding problem. An upper bound is derived and compared with lowers based on list decoding, hybrid digital-analog transmission, as well as multi-layer schemes which transmit successive refinements of the source, relying on progressive and superposed transmission with list decoding. The optimal distortion exponent is characterized for the single-input multiple-output (SIMO) and multiple-input single-output (MISO) scenarios by showing that the distortion exponent achieved by multi-layer superpositon encoding with joint decoding meets the proposed upper bound. In the MIMO scenario, the optimal distortion exponent is characterized in the low bandwidth ratio regime, and it is shown that the multi-layer superposition encoding performs very close to the upper bound in the high bandwidth expansion regime.Comment: Submitted to IEEE Transactions on Information Theor

Joint Source-Channel Coding with Time-Varying Channel and Side-Information

Transmission of a Gaussian source over a time-varying Gaussian channel is studied in the presence of time-varying correlated side information at the receiver. A block fading model is considered for both the channel and the side information, whose states are assumed to be known only at the receiver. The optimality of separate source and channel coding in terms of average end-to-end distortion is shown when the channel is static while the side information state follows a discrete or a continuous and quasiconcave distribution. When both the channel and side information states are time-varying, separate source and channel coding is suboptimal in general. A partially informed encoder lower bound is studied by providing the channel state information to the encoder. Several achievable transmission schemes are proposed based on uncoded transmission, separate source and channel coding, joint decoding as well as hybrid digital-analog transmission. Uncoded transmission is shown to be optimal for a class of continuous and quasiconcave side information state distributions, while the channel gain may have an arbitrary distribution. To the best of our knowledge, this is the first example in which the uncoded transmission achieves the optimal performance thanks to the time-varying nature of the states, while it is suboptimal in the static version of the same problem. Then, the optimal \emph{distortion exponent}, that quantifies the exponential decay rate of the expected distortion in the high SNR regime, is characterized for Nakagami distributed channel and side information states, and it is shown to be achieved by hybrid digital-analog and joint decoding schemes in certain cases, illustrating the suboptimality of pure digital or analog transmission in general.Comment: Submitted to IEEE Transactions on Information Theor

Capacity of a Class of State-Dependent Orthogonal Relay Channels

The class of orthogonal relay channels in which the orthogonal channels connecting the source terminal to the relay and the destination, and the relay to the destination, depend on a state sequence, is considered. It is assumed that the state sequence is fully known at the destination while it is not known at the source or the relay. The capacity of this class of relay channels is characterized, and shown to be achieved by the partial decode-compress-and-forward (pDCF) scheme. Then the capacity of certain binary and Gaussian state-dependent orthogonal relay channels are studied in detail, and it is shown that the compress-and-forward (CF) and partial-decode-and-forward (pDF) schemes are suboptimal in general. To the best of our knowledge, this is the first single relay channel model for which the capacity is achieved by pDCF, while pDF and CF schemes are both suboptimal. Furthermore, it is shown that the capacity of the considered class of state-dependent orthogonal relay channels is in general below the cut-set bound. The conditions under which pDF or CF suffices to meet the cut-set bound, and hence, achieve the capacity, are also derived.Comment: This paper has been accepted by IEEE Transactions on Information Theor

Escenarios de la Unión Europea para el año 2017

En particular, el presente documento de trabajo pretende establecer una hipótesis acerca del horizonte de la UE en el año 2017. Pueden preverse ciertos escenarios posibles para el futuro de la Unión. En orden ascendente, desde el menos hasta el más integracionista, se proponen los siguientes escenarios: (1) extinción; (2) geometrías variables; (3) statu quo; (4) integración creciente con geometrías variables; (5) integración creciente sin geometrías variables; y (6) unión política.Este documento de trabajo demuestra que no es descabellado que se verifique una ampliación de la UE en los próximos 10 años, como mínimo con la adhesión de Croacia, Macedonia, Albania y Montenegro y, como máximo, además de estos países, con la de Bosnia y Herzegovina y Serbia. Si ocurriera esto, aumentaría la diversidad jurídica, política y económica de la UE, dado que todos estos países son de antemano muy diferentes del resto de la Unión. La presencia de partidos políticos nacionalistas en la mayoría de ellos, unida a las divisiones étnico-sociales, podría incrementar el grado de heterogeneidad de intereses en el seno de la UE. No obstante, en lo que se refiere a las competencias, no es de esperar que los Estados miembros cedan nuevas competencias clave (en particular, en materia de defensa y de política exterior) a la UE en los próximos 10 años

European Union Bailouts and Credibility. Jean Monnet/Robert Schuman Paper Series Vol. 15 No. 4, October 2015

Since the Great Recession started, there have been eight bailouts to EU Member States, which approximate cost to the EU has been of around 380 billion euros. The aim of this paper is to analyze the legal-constitutional issues that this major bailing out operation has brought about. The conclusion is that the EU was not only ill-prepared from an economic perspective to make bailouts; it was also ill-prepared from a constitutional perspective as well, above all if one understands law, as this paper does, as a credibility device. Absent further reforms and clarifications, the current EU system of bailout governance may be prone to generate important credibility problems in the future

Alejandro Magno y su visión de la reconstrucción de la Torre de Babilonia

Die zentrale Fragestellung des folgenden Textes ist, welche Gründe Alexander den Großen dazu bewegt haben, 331 v. Chr. nach seinem Einzug in Babylon den kostenintensiven Auftrag zu geben, den Turm von Babylon wiedererrichten zu lassen. Dafür wird die Geschichte, Bedeutung und Funktion des Turmes erörtert, um seine Rolle in der babylonischen Religion einzuordnen. Alexanders Beweggründe waren mindestens dreierlei: Machtdemonstration seiner erst kürzlich erstrittenen Herrschaft, seine Bestrebung, die babylonischen Stadtgötter auf seine Seite zu ziehen und um auf seine Akzeptanz in Babylon als ausländischer König abzuzielenEl artículo trata las razones que forzaron a Alejandro Magno a iniciar la costosa reconstrucción de la Torre de Babilonia después de su entrada en Babilonia en el año 331 a. C. Discute la historia, la importancia y la función de la torre para averiguar su papel en la religión babilónica. Los motivos de Alejandro eran al menos tres: la manifestación de su poder recientemente adquirido, la atracción de los dioses babilónicos a su lado y el deseo de aprobación en Babilonia como rey de origen extranjer

Organization of Human Sperm Chromosomes During Pronuclei Formation

Chromosome organization is regarded as an important factor in regulating gene expression. In addition to the histone code, it is a part of the epigenetic mechanisms participating in fertilization and early embryonic development. Recent studies have demonstrated that chromosomes of human spermatozoa have well-defined spatial organization that includes preferred intranuclear positioning. The hypothesis of this dissertation is that sperm chromosome architecture participates in controlled transformation and activation of the paternal genome following fertilization. Adequate model systems are necessary to study early nuclear events characteristic of human fertilization. This research focused on introduction and application of heterologous intracytoplasmic sperm injection (ICSI) to study sperm chromosomes remodeling in ooplasm. ICSI of human sperm into bovine and hamster oocytes was explored in detail and the latter pair has been chosen for further studies as robust and apparently faithful models of the paternal gamete development. In this work, it was established that after ICSI: 1) sperm cells with partially digested membranes and depleted of acrosome decondense more rapidly and to a greater extent than intact cells; and 2) marked sperm-to-sperm variability in degree of chromatin swelling exists during all stages of pronuclear development as detected by DNA staining in zygotes. The latter characteristic is proposed to reflect the cryptic nuclear heterogeneity in population of morphologically, mature normal sperm. Chromatin transformation in pronuclei was established by immunolocalizaton of protamines in zygotes. Protamine withdrawal is rapid (completed within I hr) and correlates with pronuclear area rather than with specific time post ICSI. We propose that such behavior is again a consequence of hidden variability in sperm population. The final part involved the post fertilization study of two human sperm chromosomes — Homo Sapiens (HSA) chromosomes 18 and 19. Findings demonstrated that in sperm: 1) both chromosomes are packed into compact territories; and 2) similar to somatic cells, gene-rich HSA19 is positioned internally while gene-poor HSA18 peripherally. The unwinding of HSA I8/19 in developing pronuclei was described. To visualize structure remodeling of sperm chromosomes in zygotes, novel FISH procedures were developed. These findings suggest that remodeling of human sperm in heterologous ICSI faithfully mimics early steps of natural human fertilization and for the first time demonstrated several novel aspects of nuclear and chromosome reorganization during male pronuclei development