50 research outputs found

    Rearranjo de genomas : algoritmos e complexidade

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    This thesis discusses events of genome rearrangements problems: transposition, breakpoint, block interchange, short block move, and the restricted multi break. We consider problems of sorting, closest permutation, and the diameter. We develop approximation algorithms, NP-completeness and properties about these problems. Regarding the sorting by transpositions, which is an NP-complete problem, several approximation algorithms were proposed based on the graph called the reality and desire diagram. Through a case analyses of the cycles of this graph, we propose a new one which achieves so far the best 1.375 ratio and O(n log n) running time complexity. Although sorting by transpositions is NP-complete, there are several metrics whose sorting problems are polynomial or are open. In such cases, an interesting problem arises to find a permutation with maximum distance of an input permutation set at most some value, this is the closest permutation problem. We show that with respect to the polynomial distance problems of breakpoint and of block interchange, both problems are NP-complete. In order to explore properties on operations that are restriction or generalization of others, we deal with the operation of short block move and we propose the operation of restricted multi break. Regarding the short block move, we show tractable classes of permutations, properties on the permutation graph, and we show that the closest permutation problem is NP-complete. Regarding the restricted multi break, we study two versions: one where the number of non reversible blocks is bounded by a constant, and another one whose number of non reversible blocks is arbitrary. We prove tight bounds on the distance and the diameter problems for both versions.Esta tese trata de rearranjo de genomas nos eventos de: transposição, pontos de quebra, movimento de blocos, movimento de blocos curtos, e de multi corte restritos. Abordamos os problemas de ordenação, permutação mais próxima, e de diâmetro. Apresentamos algoritmos aproximativos, NP-completudes e propriedades. Sobre o problema de ordenação por transposições, provado ser NP-completo, alguns algoritmos aproximativos foram propostos baseados no grafo chamado diagrama de realidade e desejo. Através da análise dos ciclos deste grafo, propomos um novo algoritmo que atinge melhores resultados correntes, tanto de razão de aproximação de 1,375 quanto de complexidade de tempo de O(n log n). Embora ordenação por transposições seja NP-completo, há outros problemas polinomiais ou em aberto. Nestes casos, surge o desafio de encontrar uma permutação que esteja a uma distância máxima limitada por algum valor em relação a um conjunto de permutações dadas de entrada. Este é o problema de encontrar a permutação mais próxima. Mostramos que, em relação `as operações de pontos de quebra e de movimento de blocos, tais problemas são NP-completos. Com o objetivo de obter propriedades sobre operações que restingem ou generalizam outras, tratamos da operação de movimento de blocos curtos e propomos a operação de multi corte restritos. Sobre movimento de blocos curtos, mostramos classes com distâncias exatas, propriedades sobre o grafo de permutação, e mostramos que o problema de permutação mais próxima é NP-completo. Sobre multi corte restritos, tratamos de duas variações: uma cujo número de blocos não reversíveis é limitado por constante, e outra cujo número de blocos não reversíveis é arbitrário. Mostramos limites justos de distância e de diâmetro para ambas as versões

    Travels with Alex: Music for viola obbligato and various ensembles

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    Travels with Alex is a cycle of nine pieces for viola obbligato and various combinations drawn from an ensemble of 24 musicians (including two performers on Tibetan instruments). Ideally these compositions are to be played as a complete cycle, given the use of a large-scale durational interval succession to derive the relative durations of the individual pieces and sections within them. However, performance individually or in smaller combinations is also possible. The initial inspirations were twofold: the gift to the composer of a Tibetan thangka, and the travel writings of the French Buddhist, Alexandra David-Néel (1868-1969). Musically speaking, the cycle explores a range of methods, serial and otherwise, for ‘composing out’ from small, modal, mantric motifs. In Buddhist traditions, these and others like them have been used to invoke the presence of a particular bodhisattva (a ‘patron deity’, or mythical being, committed to guiding humanity towards Enlightenment) — in this case, Tārā or Jetsun Dölma, amongst whose attributes devotees prize her protection of travellers. The supporting commentary explains how these micro-elements are used to build a musical structure lasting around an hour. The commentary credits a compositional lineage featuring particular works of Tōru Takemitsu, Karlheinz Stockhausen, Peter Maxwell Davies and Jonathan Harvey. Specific technical indebtedness is also ascribed to other twentieth-century figures such as Igor Stravinsky, Michael Tippett, Elliott Carter, Witold Lutosławski, Luciano Berio and Pierre Boulez. Amongst the original features of the cycle is the juxtaposition of typical Western orchestral instruments with instruments used in Tibetan Buddhist ritual practices (played in the recording by Tibetan monks) and the inclusion of poetry in French inspired by David-Néel’s writings. The latter appears in two of the nine pieces, involving the addition of a countertenor to the instrumental ensemble

    Portfolio of Electroacoustic Compositions with Commentaries

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    This portfolio consists of electroacoustic compositions which were primarily realised through the use of corporeally informed compositional practices. The manner in which a composer interacts with the compositional tools and musical materials at their disposal is a defining factor in the creation of musical works. Although the use of computers in the practice of electroacoustic composition has extended the range of sonic possibilities afforded to composers, it has also had a negative impact on the level of physical interaction that composers have with these musical materials. This thesis is an investigation into the use of mediation technologies with the aim of circumventing issues relating to the physical performance of electroacoustic music. This line of inquiry has led me to experiment with embedded computers, wearable technologies, and a range of various sensors. The specific tools that were used in the creation of the pieces within this portfolio are examined in detail within this thesis. I also provide commentaries and analysis of the eleven electroacoustic works which comprise this portfolio, describing the thought processes that led to their inception, the materials used in their creation, and the tools and techniques that I employed throughout the compositional process

    Investigation and Quantification of FES Exercise – Isometric Electromechanics and Perceptions of Its Usage as an Exercise Modality for Various Populations

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    Functional Electrical Stimulation (FES) is the triggering of muscle contraction by use of an electrical current. It can be used to give paralyzed individuals several health benefits, through allowing artificial movement and exercise. Although many FES devices exist, many aspects require innovation to increase usability and home translation. In addition, the effect of changing electrical parameters on limb biomechanics is not entirely understood; in particular with regards to stimulation duty cycle. This thesis has two distinct components. In the first (public health component), interview studies were conducted to understand several issues related to FES technology enhancement, implementation and home translation. In the second (computational biomechanics component), novel signal processing algorithms were designed that can be used to measure mechanical responses of muscles subjected to electrical stimulation. These experiments were performed by changing duty cycle and measuring its effect on quadriceps-generated knee torque. The studies of this thesis have presented several ideas, toolkits and results which have the potential to guide future FES biomechanics studies and the translatability of systems into regular usage for patients. The public health studies have provided conceptual frameworks upon which FES may be used in the home by patients. In addition, they have elucidated a range of issues that need to be addressed should FES technology reach its true potential as a therapy. The computational biomechanics studies have put forward novel data analysis techniques which may be used for understanding how muscle responds to electrical stimulation, as measured via torque. Furthermore, the effect of changing the electrical stimulation duty cycle on torque was successfully described, adding to an understanding of how electrical stimulation parameter modulation can influence joint biomechanics

    States of suspension : exploring suspended experience of sound and light in popular music and imagery

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    This practice-based research project explores, defines and demonstrates the state of spatio-temporal suspension, or suspended experience, where abstract characteristics of sound and light in music and imagery coalesce to afford audience and performer the experience of liminal or “between” aesthetic zones, in turn providing a gateway into imaginative worlds. Informed by the author’s background in the performance and composition of forms of experimental popular music as well as graphic design and photography, the investigation utilises a combination of creative research methods and research-led analysis within a phenomenological framework to interrogate the physiological and neurological basis for this state. In order to better understand and define this concept, relevant creative exemplars including music and music videos, experimental films and site-specific installations are examined. The analysis draws upon a range of relevant philosophies and theories of perception relating to time and space, including phenomenology, liminality, the Japanese concept of Ma and heterotopia. Perceptual and psychological theories, including affect as felt experience and its role in aesthetics are considered, as well as embodied cognition in aesthetics and ecological approaches to perception. These theories and concepts consider humans as integral parts of a dynamic ecosystem of individual and shared information and perception, providing insight into the perceptual basis of suspension and why it is often encountered as a cross-modal experience. Through the analysis of creative works and the author’s self-observation and journaling of the audiovisual exploration of suspension in performance and practice, the research identifies compositional features that are prevalent in works that facilitate and enhance the potential for suspended experience. These features are explored and realised through creative works that examine how suspension is imparted through an audiovisual composition, how it is experienced by the practitioner through the recording process and as an improvised performance, and how the works are received and experienced by others, via examination of responses to specially designed reception tests. The findings are expressed in the conception and realisation of two major bodies of work: an audiovisual suite, Suspension Studies (2020), comprised of musical and visual studies of suspension as an immobile work; and a site-specific performance work, States of Suspension (2018), which affords audiences and performers an active aesthetic experience of suspension in situ. The enquiry contributes to the understanding of a relatively unexplored phenomenon in music and visual arts and intends to encourage further discourse and investigation into this topic

    FinBook: literary content as digital commodity

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    This short essay explains the significance of the FinBook intervention, and invites the reader to participate. We have associated each chapter within this book with a financial robot (FinBot), and created a market whereby book content will be traded with financial securities. As human labour increasingly consists of unstable and uncertain work practices and as algorithms replace people on the virtual trading floors of the worlds markets, we see members of society taking advantage of FinBots to invest and make extra funds. Bots of all kinds are making financial decisions for us, searching online on our behalf to help us invest, to consume products and services. Our contribution to this compilation is to turn the collection of chapters in this book into a dynamic investment portfolio, and thereby play out what might happen to the process of buying and consuming literature in the not-so-distant future. By attaching identities (through QR codes) to each chapter, we create a market in which the chapter can ‘perform’. Our FinBots will trade based on features extracted from the authors’ words in this book: the political, ethical and cultural values embedded in the work, and the extent to which the FinBots share authors’ concerns; and the performance of chapters amongst those human and non-human actors that make up the market, and readership. In short, the FinBook model turns our work and the work of our co-authors into an investment portfolio, mediated by the market and the attention of readers. By creating a digital economy specifically around the content of online texts, our chapter and the FinBook platform aims to challenge the reader to consider how their personal values align them with individual articles, and how these become contested as they perform different value judgements about the financial performance of each chapter and the book as a whole. At the same time, by introducing ‘autonomous’ trading bots, we also explore the different ‘network’ affordances that differ between paper based books that’s scarcity is developed through analogue form, and digital forms of books whose uniqueness is reached through encryption. We thereby speak to wider questions about the conditions of an aggressive market in which algorithms subject cultural and intellectual items – books – to economic parameters, and the increasing ubiquity of data bots as actors in our social, political, economic and cultural lives. We understand that our marketization of literature may be an uncomfortable juxtaposition against the conventionally-imagined way a book is created, enjoyed and shared: it is intended to be

    Foods of Association

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    This fascinating book examines the biology and culture of foods and beverages that are consumed in communal settings, with special attention to their health implications. Nina Etkin covers a wealth of topics, exploring human evolutionary history, the Slow Food movement, ritual and ceremonial foods, caffeinated beverages, spices, the street foods of Hawaii and northern Nigeria, and even bottled water. Her work is framed by a biocultural perspective that considers both the physiological implications of consumption and the cultural construction and circulation of foods
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