Symbol synchronization exploiting the symmetric property in optical fast OFDM

We propose a new simple method to achieve precise symbol synchronization using one start-of-frame (SOF) symbol in optical fast orthogonal frequency-division multiplexing (FOFDM) with subchannel spacing equal to half of the symbol rate per sub-carrier. The proposed method first identifies the SOF symbol, then exploits the evenly symmetric property of the discrete cosine transform in FOFDM, which is also valid in the presence of chromatic dispersion, to achieve precise symbol synchronization. We demonstrate its use in a 16.88-Gb/s phase-shifted-keying-based FOFDM system over a 124-km field-installed single-mode fiber link and show that this technique operates well in automatic precise symbol synchronization at an optical signal-to-noise ratio as low as 3 dB and after transmission.

Multilevel amplitude regeneration of 256-symbol constellation

We propose a novel scheme for multilevel (9 and more) amplitude regeneration based on nonlinear optical loop mirror and demonstrate its efficiency and cascadability on 256-symbol constellation. © 2014 OSA.

Metaphors in Hugo Chávez's political discourse:conceptualizing nation, revolution and opposition

This book provides the first comprehensive analysis of metaphors used by Hugo Chávez in his efforts to construct and legitimize his Bolivarian Revolution. It focuses on metaphors drawn from three of his most frequent target domains: the nation, his revolution, and the opposition. The author argues that behind an official discourse of inclusion, Chávez's choice of metaphors contributes to the construction of a polarizing discourse of exclusion in which his political opponents are represented as enemies of the nation. Chávez constructs this polarizing discourse of exclusion by combining metaphors that conceptualize: (a) the nation as a person who has been resurrected by his government, as a person ready to fight for his revolution, or as Chávez himself; (b) the revolution as war; and (c) members of the opposition as war combatants or criminals. At the same time, by making explicit references in his discourse about the revolution as the continuation of Simón Bolívar's wars of independence, Chávez contributes to represent opponents as enemies of the nation, given that in the Venezuelan collective imaginary Bolívar is the symbol of the nation's emancipation.

Digital video transmission over wireless networks

The advent of the Integrated Services Digital Network (ISDN) led to the standardisation of the first video codecs for interpersonal video communications, followed closely by the development of standards for the compression, storage and distribution of digital video in the PC environment, mainly targeted at CD-ROM storage. At the same time the second-generation digital wireless networks, and the third-generation networks being developed, have enough bandwidth to support digital video services. The radio propagation medium is a difficult environment in which to deploy low bit error rate, real time services such as video. The video coding standards designed for ISDN and storage applications, were targeted at low bit error rate levels, orders of magnitude lower than the typical bit error rates experienced on wireless networks. This thesis is concerned with the transmission of digital, compressed video over wireless networks. It investigates the behaviour of motion compensated, hybrid interframe DPCM/DCT video coding algorithms, which form the basis of current coding algorithms, in the presence of high bit error rates commonly found on digital wireless networks. A group of video codecs, based on the ITU-T H.261 standard, are developed which are robust to the burst errors experienced on radio channels. The radio link is simulated at low level, to generate typical error files that closely model real world situations, in a Rayleigh fading environment perturbed by co-channel interference, and on frequency selective channels which introduce inter symbol interference. Typical anti-multipath techniques, such as antenna diversity, are deployed to mitigate the effects of the channel. Link layer error control techniques are also investigated.

A mean field theory of coded CDMA systems

We present a mean field theory of code-division multiple access (CDMA) systems with error-control coding. On the basis of the relation between the free energy and mutual information, we obtain an analytical expression of the maximum spectral efficiency of the coded CDMA system, from which a mean field description of the coded CDMA system is provided in terms of a bank of scalar Gaussian channels whose variances in general vary at different code symbol positions. Regular low-density parity-check (LDPC)-coded CDMA systems are also discussed as an example of the coded CDMA systems.

A linguistic and semantic approach to the theory and practice of literary translation

This work explores the relevance of semantic and linguistic description to translation, theory and practice. It is aimed towards a practical model of approach to texts to translate. As literary texts [poetry mainly] are the focus of attention, so are stylistic matters. Note, however, that 'style', and, to some extent, the conclusions of the work, are not limited to so-called literary texts. The study of semantic description reveals that most translation problems do not stem from the cognitive (langue-related), but rather from the contextual (parole-related) aspects of meaning. Thus, any linguistic model that fails to account for the latter is bound to fall short. T.G.G. does, whereas Systemics, concerned with both the 'Iangue' and 'parole' (stylistic and sociolinguistic mainly) aspects of meaning, provides a useful framework of approach to texts to translate. Two essential semantic principles for translation are: that meaning is the property of a language (Firth); and the 'relativity of meaning assignments' (Tymoczko). Both imply that meaning can only be assessed, correctly, in the relevant socio-cultural background. Translation is seen as a restricted creation, and the translator's encroach as a three-dimensional critical one. To encompass the most technical to the most literary text, and account for variations in emphasis in any text, translation theory must be based on typology of function Halliday's ideational, interpersonal and textual, or, Buhler's symbol, signal, symptom, Functions3. Function Coverall and specific] will dictate aims and method, and also provide the critic with criteria to assess translation Faithfulness. Translation can never be reduced to purely objective methods, however. Intuitive procedures intervene, in textual interpretation and analysis, in the choice of equivalents, and in the reception of a translation. Ultimately, translation, theory and practice, may perhaps constitute the touchstone as regards the validity of linguistic and semantic theories.

Solidarity and power in German : language as political action : a contribution to the socio-cultural history of the German language

Germany's latest attempt at unification raises again the question of German nationhood and nationality. The present study examines the links between the development of the German language and the political history of Germany, principally in the nineteenth and twentieth centuries. By examining the role of language in the establishment and exercise of political power and in the creation of national and group solidarity in Germany, the study both provides insights into the nature of language as political action and contributes to the socio-cultural history of the German language. The language-theoretical hypothesis on which the study is based sees language as a central factor in political action, and opposes the notion that language is a reflection of underlying political 'realities' which exist independently of language. Language is viewed as language-in-text which performs identifiable functions. Following Leech, five functions are distinguished, two of which (the regulative and the phatic) are regarded as central to political processes. The phatic function is tested against the role of the German language as a creator and symbol of national identity, with particular attention being paid to concepts of the 'purity' of the language. The regulative function (under which a persuasive function is also subsumed) is illustrated using the examples of German fascist discourse and selected cases from German history post-1945. In addition, the interactions are examined between language change and socio-economic change by postulating that language change is both a condition and consequence of socio-economic change, in that socio-economic change both requires and conditions changes in the communicative environment. Finally, three politocolinguistic case studies from the eight and ninth decades of the twentieth century are introduced in order to demonstrate specific ways in which language has been deployed in an attempt to create political realities, thus verifying the initial hypothesis of the centrality of language to the political process.

The development of a new compiler-compiler front-end

The increasing cost of developing complex software systems has created a need for tools which aid software construction. One area in which significant progress has been made is with the so-called Compiler Writing Tools (CWTs); these aim at automated generation of various components of a compiler and hence at expediting the construction of complete programming language translators. A number of CWTs are already in quite general use, but investigation reveals significant drawbacks with current CWTs, such as lex and yacc. The effective use of a CWT typically requires a detailed technical understanding of its operation and involves tedious and error-prone input preparation. Moreover, CWTs such as lex and yacc address only a limited aspect of the compilation process; for example, actions necessary to perform lexical symbol valuation and abstract syntax tree construction must be explicitly coded by the user. This thesis presents a new CWT called CORGI (COmpiler-compiler from Reference Grammar Input) which deals with the entire `front-end' component of a compiler; this includes the provision of necessary data structures and routines to manipulate them, both generated from a single input specification. Compared with earlier CWTs, CORGI has a higher-level and hence more convenient user interface, operating on a specification derived directly from a `reference manual' grammar for the source language. Rather than developing a compiler-compiler from first principles, CORGI has been implemented by building a further shell around two existing compiler construction tools, namely lex and yacc. CORGI has been demonstrated to perform efficiently in realistic tests, both in terms of speed and the effectiveness of its user interface and error-recovery mechanisms.

Nationalism gone global:the Hauptverband Deutscher Flottenvereine im Auslande 1898-1918

The Wilhelmine battle fleet was a powerful symbol of national strength and unity not only within the Reich but also in German ethnic communities abroad. A global network of 179 navy clubs with 9,500 members (1913) was coordinated by the Berlin-based Central League for German Navy Clubs Abroad (Hauptverband Deutscher Flottenvereine im Auslande). Its aims were the collection of migrants’ money for concrete navy projects and the promotion of allegiance to the Reich and of ethnic cohesion abroad. The article analyses German navy campaigning within a transnational framework and supports the view that migrants were discursively drawn into Imperial Germany’s global aspirations as outposts of ‘Germanness’ abroad. Existing scholarship, however, tends to look at them as passive objects of a discourse conducted within Germany, as a canvas onto which (semi-)colonial fantasies could be projected. This article argues, rather, that ‘Germans abroad’ could also be active participants within a transnationally conducted and multi-directional discourse. They did not necessarily defy nationalist assumptions but could, in fact, be deeply embedded in the construction of these assumptions.

The concept of symphonia in contemporary European Orthodoxy

The relationship between the religious and political fields in the Orthodox Church is defined by the concept of symphonia which dates back to the Byzantine Empire. The concept suggests that the religious and political authorities should work together in a symphonic agreement towards achieving the material and spiritual welfare of the faithful. This article argues that an investigation of the theory of sign and symbol offers a better understanding of symphonia and, in particular, of its relationship with the nation-building process. From this perspective, by corroborating the data provided by the European Values Survey from 1990 to 2000 with this theory, this article demonstrates that the enlargement of the European Union represents the most significant challenge to symphonia, shifting its national focus to a supranational level. © 2011 Taylor & Francis.

On the utility of alternative amino acid scripts

In this work we propose the hypothesis that replacing the current system of representing the chemical entities known as amino acids using Latin letters with one of several possible alternative symbolic representations will bring significant benefits to the human construction, modification, and analysis of multiple protein sequence alignments. We propose ways in which this might be done without prescribing the choice of actual scripts used. Specifically we propose and explore three ways to encode amino acid texts using novel symbolic alphabets free from precedents. Primary orthographic encoding is the direct substitution of a new alphabet for the standard, Latin-based amino acid code. Secondary encoding imposes static residue groupings onto the orthography of the alphabet by manipulating the shape and/or orientation of amino acid symbols. Tertiary encoding renders each residue as a composite symbol; each such symbol thus representing several alternative amino acid groupings simultaneously. We also propose that the use of a new group-focussed alphabet will free the colouring of amino acid residues often used as a tool to facilitate the representation or construction of multiple alignments for other purposes, possibly to indicate dynamic properties of an alignment such as position-wise residue conservation.

Metaphors in Hugo Chávez's political discourse:conceptualizing nation, revolution and opposition

This dissertation examines Hugo Chávez's choice of metaphors in his efforts to construct and legitimize his Bolivarian Revolution. It focuses on metaphors drawn from three of the most frequent target domains present in his discourse: the nation, his revolution, and the opposition. The study argues that behind an official discourse of inclusion, Chávez's choice of metaphors contributes to the construction of a polarizing discourse of exclusion in which his political opponents are represented as enemies of the nation.The study shows that Chávez constructs this polarizing discourse of exclusion by combining metaphors that conceptualize: (a) the nation as a person who has been resurrected by his government, as a person ready to fight for his revolution, or as Chávez himself; (b) the revolution as war; and (c) members of the opposition as war combatants or criminals. At the same time, the study shows that by making explicit references in his discourse about the revolution as the continuation of Bolívar's wars of independence, Chávez contributes to represent opponents as enemies of the nation, given that in the Venezuelan collective imaginary Simón Bolívar is the symbol of the nation's emancipation.This research, which covers a period of nine years (from Chávez's first year in office in 1999 through 2007), is part of the discipline of Political Discourse Analysis (PDA). It is anchored both in the theoretical framework provided by the cognitive linguistic metaphor theory developed by George Lakoff and Mark Johnson described in their book Metaphors We Live By, and in Critical Metaphor Analysis (CMA) as defined by Jonathan Charteris-Black in his book Corpus Approaches to Critical Metaphor Analysis.The study provides the first comprehensive analysis of metaphors used by Chávez in his political discourse. It builds upon the findings of previous studies on political discourse analysis in Venezuela by showing that Chávez's discourse not only polarizes the country and represents opponents as detractors of national symbols such as Bolívar or his wars of independence (which have been clearly established in previous studies), but also represents political opponents as enemies of the nation.

MAP detection for impairment compensation in coherent WDM systems

We propose a novel recursive-algorithm based maximum a posteriori probability (MAP) detector in spectrally-efficient coherent wavelength division multiplexing (CoWDM) systems, and investigate its performance in a 1-bit/s/Hz on-off keyed (OOK) system limited by optical-signal-to-noise ratio. The proposed method decodes each sub-channel using the signal levels not only of the particular sub-channel but also of its adjacent sub-channels, and therefore can effectively compensate deterministic inter-sub-channel crosstalk as well as inter-symbol interference arising from narrow-band filtering and chromatic dispersion (CD). Numerical simulation of a five-channel OOK-based CoWDM system with 10Gbit/s per channel using either direct or coherent detection shows that the MAP decoder can eliminate the need for phase control of each optical carrier (which is necessarily required in a conventional CoWDM system), and greatly relaxes the spectral design of the demultiplexing filter at the receiver. It also significantly improves back-to-back sensitivity and CD tolerance of the system.

Offset-QAM based coherent WDM for spectral efficiency enhancement

Optically multiplexed multi-carrier systems with channel spacing reduced to the symbol rate per carrier are highly susceptible to inter-channel crosstalk, which places stringent requirements for the specifications of system components and hinders the use of high-level formats. In this paper, we investigate the performance benefits of using offset 4-, 16-, and 64-quadrature amplitude modulation (QAM) in coherent wavelength division multiplexing (CoWDM). We compare this system with recently reported Nyquist WDM and no-guard-interval optical coherent orthogonal frequency division multiplexing, and show that the presented system greatly relaxes the requirements for device specifications and enhances the spectral efficiency by enabling the use of high-level QAM. The achieved performance can approach the theoretical limits using practical components.

Experimental and theoretical investigations of intensity-modulation and direct-detection optical fast-OFDM over MMF-links

We demonstrate the first experimental implementation of a 3.9-Gb/s differential binary phase-shift keying (DBPSK)-based double sideband (DSB) optical fast orthogonal frequency-division-multiplexing (FOFDM) system with a reduced subcarrier spacing equal to half the symbol rate over 300m of multimode fiber (MMF) using intensity-modulation and direct-detection (IM/DD). The required received optical power at a bit-error rate (BER) of 10(-3) was measured to be similar to -14.2 dBm with a receiver sensitivity penalty of only similar to 0.2 dB when compared to the back-to-back case. Experimental results agree very well with the theoretical predictions.