1,876 research outputs found

    A Faster Implementation of Online Run-Length Burrows-Wheeler Transform

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    Run-length encoding Burrows-Wheeler Transformed strings, resulting in Run-Length BWT (RLBWT), is a powerful tool for processing highly repetitive strings. We propose a new algorithm for online RLBWT working in run-compressed space, which runs in O(nlgr)O(n\lg r) time and O(rlgn)O(r\lg n) bits of space, where nn is the length of input string SS received so far and rr is the number of runs in the BWT of the reversed SS. We improve the state-of-the-art algorithm for online RLBWT in terms of empirical construction time. Adopting the dynamic list for maintaining a total order, we can replace rank queries in a dynamic wavelet tree on a run-length compressed string by the direct comparison of labels in a dynamic list. The empirical result for various benchmarks show the efficiency of our algorithm, especially for highly repetitive strings.Comment: In Proc. IWOCA201

    Compressed Data Structures for Dynamic Sequences

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    We consider the problem of storing a dynamic string SS over an alphabet Σ={1,,σ}\Sigma=\{\,1,\ldots,\sigma\,\} in compressed form. Our representation supports insertions and deletions of symbols and answers three fundamental queries: access(i,S)\mathrm{access}(i,S) returns the ii-th symbol in SS, ranka(i,S)\mathrm{rank}_a(i,S) counts how many times a symbol aa occurs among the first ii positions in SS, and selecta(i,S)\mathrm{select}_a(i,S) finds the position where a symbol aa occurs for the ii-th time. We present the first fully-dynamic data structure for arbitrarily large alphabets that achieves optimal query times for all three operations and supports updates with worst-case time guarantees. Ours is also the first fully-dynamic data structure that needs only nHk+o(nlogσ)nH_k+o(n\log\sigma) bits, where HkH_k is the kk-th order entropy and nn is the string length. Moreover our representation supports extraction of a substring S[i..i+]S[i..i+\ell] in optimal O(logn/loglogn+/logσn)O(\log n/\log\log n + \ell/\log_{\sigma}n) time

    Defining the gap between research and practice in public relations programme evaluation - towards a new research agenda

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    The current situation in public relations programme evaluation is neatly summarized by McCoy who commented that 'probably the most common buzzwords in public relations in the last ten years have been evaluation and accountability' (McCoy 2005, 3). This paper examines the academic and practitioner-based literature and research on programme evaluation and it detects different priorities and approaches that may partly explain why the debate on acceptable and agreed evaluation methods continues. It analyses those differences and proposes a research agenda to bridge the gap and move the debate forward

    Sceptical Employees as CSR Ambassadors in Times of Financial Uncertainty

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    This chapter offers new insights into the understanding of internal (employee) perceptions of organizational corporate social responsibility (CSR) policies and strategies. This study explores the significance of employees’ involvement and scepticism upon CSR initiatives and focuses on the effects it may have upon word of mouth (WOM) and the development of employee–organisation relationships. Desk research introduces the research questions. Data for the research questions were gathered through a self-completion questionnaire distributed in a hardcopy form to the sample. An individual’s level of scepticism and involvement appears to affect the development of a positive effect on employees’ WOM. Involvement with the domain of the investment may be a central factor affecting relationship building within the organization, and upon generation of positive WOM. The chapter offers a conceptual framework to public relations (PR) and corporate communications practitioners, which may enrich their views and understanding of the use and value of CSR for communication strategies and practices. For-profit organisations are major institutions in today’s society. CSR is proffered as presenting advantages for (at macro level) society and (micro level) the organization and its employees. Concepts, such as involvement and scepticism, which have not been rigorously examined in PR and corporate communication literature, are addressed. By examining employee perceptions, managers and academic researchers gain insights into the acceptance, appreciation and effectiveness of CSR policies and activities upon the employee stakeholder group. This will affect current and future CSR communication strategies. The knowledge acquired from this chapter may be transferable outside the for-profit sector

    Intraspecies diversity of SARS-like coronaviruses in Rhinolophus sinicus and its implications for the origin of SARS coronaviruses in humans

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    The Chinese rufous horseshoe bat (Rhinolophus sinicus) has been suggested to carry the direct ancestor of severe acute respiratory syndrome (SARS) coronavirus (SCoV), and the diversity of SARS-like CoVs (SLCoV) within this Rhinolophus species is therefore worth investigating. Here, we demonstrate the remarkable diversity of SLCoVs in R. sinicus and identify a strain with the same pattern of phylogenetic incongruence (i.e. an indication of recombination) as reported previously in another SLCoV strain. Moreover, this strain possesses a distinctive 579 nt deletion in the nsp3 region that was also found in a human SCoV from the late-phase epidemic. Phylogenetic analysis of the Orf1 region suggested that the human SCoVs are phylogenetically closer to SLCoVs in R. sinicus than to SLCoVs in other Rhinolophus species. These findings reveal a closer evolutionary linkage between SCoV in humans and SLCoVs in R. sinicus, defining the scope of surveillance to search for the direct ancestor of human SCoVs. © 2010 SGM.published_or_final_versio

    Optoacoustic solitons in Bragg gratings

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    Optical gap solitons, which exist due to a balance of nonlinearity and dispersion due to a Bragg grating, can couple to acoustic waves through electrostriction. This gives rise to a new species of ``gap-acoustic'' solitons (GASs), for which we find exact analytic solutions. The GAS consists of an optical pulse similar to the optical gap soliton, dressed by an accompanying phonon pulse. Close to the speed of sound, the phonon component is large. In subsonic (supersonic) solitons, the phonon pulse is a positive (negative) density variation. Coupling to the acoustic field damps the solitons' oscillatory instability, and gives rise to a distinct instability for supersonic solitons, which may make the GAS decelerate and change direction, ultimately making the soliton subsonic.Comment: 5 pages, 3 figure

    Effects of broadening and electron overheating in tunnel structures based on metallic clusters

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    We study the influence of energy levels broadening and electron subsystem overheating in island electrode (cluster) on current-voltage characteristics of three-electrode structure. A calculation scheme for broadening effect in one-dimensional case is suggested. Estimation of broadening is performed for electron levels in disc-like and spherical gold clusters. Within the two-temperature model of metallic cluster and by using a size dependence of the Debye frequency the effective electron temperature as a function of bias voltage is found approximately. We suggest that the effects of broadening and electron overheating are responsible for the strong smoothing of current-voltage curves, which is observed experimentally at low temperatures in structures based on clusters consisting of accountable number of atoms.Comment: 8 pages, 5 figure

    'Everyday memory' impairments in autism spectrum disorders

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    ‘Everyday memory’ is conceptualised as memory within the context of day-to-day life and, despite its functional relevance, has been little studied in individuals with autism spectrum disorders (ASDs). In the first study of its kind, 94 adolescents with an ASD and 55 without an ASD completed measures of everyday memory from the Rivermead Behavioural Memory Test (RBMT) and a standard word recall task (Children’s Auditory Verbal Learning Test-2: CAVLT-2). The ASD group showed significant impairments on the RBMT, including in prospective memory, alongside impaired performance on the CAVLT-2. Social and communication ability was significantly associated with prospective remembering in an everyday memory context but not with the CAVLT-2. The complex nature of everyday memory and its relevance to ASD is discussed
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