Astrophysical Sources of Stochastic Gravitational-Wave Background

We review the spectral properties of stochastic backgrounds of astrophysical origin and discuss how they may differ from the primordial contribution by their statistical properties. We show that stochastic searches with the next generation of terrestrial interferometers could put interesting constrains on the physical properties of astrophysical populations, such as the ellipticity and magnetic field of magnetars, or the coalescence rate of compact binaries.Comment: 12 pages, 3 figures,accepted for publication in CQG, GWDAW12 conference proceedings version corrected in comparison published version where we found an error in equation (4

A Unifying Approach to Quaternion Adaptive Filtering: Addressing the Gradient and Convergence

A novel framework for a unifying treatment of quaternion valued adaptive filtering algorithms is introduced. This is achieved based on a rigorous account of quaternion differentiability, the proposed I-gradient, and the use of augmented quaternion statistics to account for real world data with noncircular probability distributions. We first provide an elegant solution for the calculation of the gradient of real functions of quaternion variables (typical cost function), an issue that has so far prevented systematic development of quaternion adaptive filters. This makes it possible to unify the class of existing and proposed quaternion least mean square (QLMS) algorithms, and to illuminate their structural similarity. Next, in order to cater for both circular and noncircular data, the class of widely linear QLMS (WL-QLMS) algorithms is introduced and the subsequent convergence analysis unifies the treatment of strictly linear and widely linear filters, for both proper and improper sources. It is also shown that the proposed class of HR gradients allows us to resolve the uncertainty owing to the noncommutativity of quaternion products, while the involution gradient (I-gradient) provides generic extensions of the corresponding real- and complex-valued adaptive algorithms, at a reduced computational cost. Simulations in both the strictly linear and widely linear setting support the approach

Copyright and Technology: Hearing the Dissonance

This thesis concerns copyright and technology. It investigates their ever-growing dissonance, currently intensified by the processes of digitisation taking place in society at large. If there is a pressing need to reassess/modify copyright law against the backdrop of digital technology, the thesis argues that a prerequisite of this is that it divorces itself from the limitations in the existing copyright paradigm and, accordingly, recognise technology as a quality and condition for both its emergence and subsistence. In contrast to the prevailing tradition of viewing technology as an extrinsic condition affecting copyright, here its intrinsic quality is traced and emphasised. This is accomplished by means of circumventing copyright’s fundamental orienting principle of property and drawing instead on the notion of communication, which in turn enables us to recognise and reconstitute the ever-present intertwinement of copyright and technology. While communication as an approach is not foreign to the copyright discourse, it has rarely been deployed in investigating the relation between copyright and technology. The thesis advances from an understanding of communication focused on the end points and recognises the middle as a prerequisite and an essential element of communication. This shift in view does not only allow recognition of noise as an intrinsic feature of communication but also becomes a methodological tool through which the dissonance of copyright and technology can be ‘heard’ and comprehended. In doing so, the thesis draws on information theory, the work of the French philosopher Michel Serres, media and sound studies. By traversing different fields of study, in the end, the thesis immerses itself into a soundscape, and thus ‘aurality’ becomes a sensible manner for answering the guiding research question of what is the actual dissonance between copyright and technology. Ultimately, it argues that this manner of displacement provides new passages of investigation that go beyond the limitations of copyright’s normativity, and sets a conceptual basis for addressing the issues and re-articulating the relation between copyright and technology

Copyright and Heritage: Relation, Origin, Temporality

If there is one feature that frames the conceptual and normative foundations for both copyright law and cultural heritage it is the principle of origin. For a copyright to subsist the law requires an original expression that establishes the origin upon which it recognises the author and subsequently actualises the existence of property rights over that expression. For the cultural heritage, it is the origin of in/tangible manifestations and expressions that becomes the principle according to which belonging, identity, and tradition are recognised and established. While the concept of cultural heritage has arguably been comparable to the notion of ‘cultural property’, this nevertheless indicates that ‘heritage’ still negotiates its status within the various discourses that enclose and view cultural expressions, resources, artefacts through the perspectives of property and ownership – the principles associated with the very legal tradition that copyright law originates from. The approach of studying the relationship between copyright law and cultural heritage is often considered through the prism of proprietary notions and the distinctions they entail: private/public, individual/collective. The questions about the way and extent to which they contrast, or for that matter overlap, are pertinent when contextualising their subject matter. Indeed, the protection and promotion of culture, understood here in its broadest sense, remain to inform the justifications for their normative construction. However, what fundamentally embodies their existence is the understanding of origin as a temporal quality, which gives rise to their narratives, histories, memories, preservation (of themselves and their subject matter). As the French philosopher Michel Serres notes: the time moves ‘along a line of origin…[which] is not a point, [but] ‘a long sequence of founding circumstances.'(1) This paper approaches time as an inherent principle of both copyright law and cultural heritage in conceptualising and comparing their subject matter. More specifically, it argues that it is their use and understanding of time – as a measure and function – that provides an alternative approach to question how time is subsumed into normative conceptions, how it is used to regulate and impose, how it gives rise to property rights, how it informs narratives and their ‘timelessness’. While copyright is a temporal category that only temporary preserves, the cultural heritage builds itself by the very transmission of notions, ideas, skills, knowledge, and artefacts that further solidify the foundation of its continuance. Their value is not only related to the temporal significance, or preserving the facts that contextualise and provide evidence for cultural development, but also of recognising their inherent relation to time (future and past) as a trace that informs understanding of a particular system, civilisation, legal practice or mode of thinking. (1) Michel Serres, Rome: The First Book of Foundations (Bloomsbury, 2015) 220