1,282 research outputs found

    Range Queries on Uncertain Data

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    Given a set PP of nn uncertain points on the real line, each represented by its one-dimensional probability density function, we consider the problem of building data structures on PP to answer range queries of the following three types for any query interval II: (1) top-11 query: find the point in PP that lies in II with the highest probability, (2) top-kk query: given any integer knk\leq n as part of the query, return the kk points in PP that lie in II with the highest probabilities, and (3) threshold query: given any threshold τ\tau as part of the query, return all points of PP that lie in II with probabilities at least τ\tau. We present data structures for these range queries with linear or nearly linear space and efficient query time.Comment: 26 pages. A preliminary version of this paper appeared in ISAAC 2014. In this full version, we also present solutions to the most general case of the problem (i.e., the histogram bounded case), which were left as open problems in the preliminary versio

    Assessing direct contributions of morphological awareness and prosodic sensitivity to children’s word reading and reading comprehension

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    We examined the independent contributions of prosodic sensitivity and morphological awareness to word reading, text reading accuracy, and reading comprehension. We did so in a longitudinal study of English-speaking children (N = 70). At 5 to 7 years of age, children completed the metalinguistic measures along with control measures of phonological awareness and vocabulary. Children completed the reading measures two years later. Morphological awareness, but not prosodic sensitivity made a significant independent contribution to word reading, text reading accuracy and reading comprehension. The effects of morphological awareness on reading comprehension remained after controls for word reading. These results suggest that morphological awareness needs to be considered seriously in models of reading development and that prosodic sensitivity might have primarily indirect relations to reading outcomes. Keywords: Morphological Awareness; Prosody; Word Reading; Reading Comprehension

    Selection from read-only memory with limited workspace

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    Given an unordered array of NN elements drawn from a totally ordered set and an integer kk in the range from 11 to NN, in the classic selection problem the task is to find the kk-th smallest element in the array. We study the complexity of this problem in the space-restricted random-access model: The input array is stored on read-only memory, and the algorithm has access to a limited amount of workspace. We prove that the linear-time prune-and-search algorithm---presented in most textbooks on algorithms---can be modified to use Θ(N)\Theta(N) bits instead of Θ(N)\Theta(N) words of extra space. Prior to our work, the best known algorithm by Frederickson could perform the task with Θ(N)\Theta(N) bits of extra space in O(NlgN)O(N \lg^{*} N) time. Our result separates the space-restricted random-access model and the multi-pass streaming model, since we can surpass the Ω(NlgN)\Omega(N \lg^{*} N) lower bound known for the latter model. We also generalize our algorithm for the case when the size of the workspace is Θ(S)\Theta(S) bits, where lg3NSN\lg^3{N} \leq S \leq N. The running time of our generalized algorithm is O(Nlg(N/S)+N(lgN)/lgS)O(N \lg^{*}(N/S) + N (\lg N) / \lg{} S), slightly improving over the O(Nlg(N(lgN)/S)+N(lgN)/lgS)O(N \lg^{*}(N (\lg N)/S) + N (\lg N) / \lg{} S) bound of Frederickson's algorithm. To obtain the improvements mentioned above, we developed a new data structure, called the wavelet stack, that we use for repeated pruning. We expect the wavelet stack to be a useful tool in other applications as well.Comment: 16 pages, 1 figure, Preliminary version appeared in COCOON-201

    Multi-Informant Predictors of Social Inclusion for Students with Autism Spectrum Disorders Attending Mainstream School

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    This study examined differential profiles of behavioural characteristics predictive of successful inclusion in mainstream education for children with autism spectrum disorders (ASD) and comparison students. Multiple regression analyses using behavioural ratings from parents, teachers and peers found some evidence for differential profiles predicting peer acceptance and rejection. High levels of peer-rated shyness significantly predicted social rejection in comparison students only. Parent-rated prosocial behaviour also differentially predicted social acceptance; high-levels of prosocial behaviour predicted acceptance in comparison students, but low-levels were predictive for students with ASD. These findings suggest that schools may seek to augment traditional social skills programmes with awareness raising about ASD among mainstream pupils to utilise peers’ apparent willingness to discount characteristics such as ‘shyness’

    Secondary conidiation of Sphacelia sorghi on sorghum, a novel factor in the epidemiology of ergot disease

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    Sphacelia sorghi, the ergot pathogen of sorghum in Zimbabwe, causes copious exudation of honeydew containing macroconidia. Within a few days the exudate develops a white crust consisting of a layer of secondary conidia borne above the honeydew surface on a palisade of sterigma-like projecting hyphae which arise from the macroconidia immediately below the honeydew surface. Secondary conidia are windborne, initiate infection and are recognized for the first time to have an important role in the epidemiology of ergot disease of sorghum in Southern Afric

    Windborne spread of ergot disease (Claviceps africana) in sorghum A-lines in Zimbabwe

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    In field trials in Zimbabwe, C. africana spread rapidly through replicated plots of male-sterile sorghum A-lines, from a group of centrally situated, inoculated plants. Prominent secondary conidiation by the pathogen on the surface of exuded honeydew provided airborne spores which were trapped in a Burkard continuous spore trap and showed diurnal peaks in air close to the primary inoculum source. From the rate and pattern of disease spread it is concluded that the characteristic secondary conidia of C. africana were the principal disease agents within the experimental area, and that ergot spread by windborne secondary conidia has significant epidemiological and economic implications for sorghum hybrid breeding in southern Africa

    Claviceps africana sp. nov.; the distinctive ergot pathogen of sorghum in Africa

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    Stromata arising from ergot sclerotia from sorghum in Zimbabwe were different in colour and texture from those of Claviceps sorghi from sorghum in India, compounding other differences in the dynamics of the early stages of parasitism, the sugar composition of honeydew, the quantitative expression of secondary conidiation and the morphology of sclerotia. The distinctive sexual stage forms the basis of describing the African material as a new Claviceps species which also uniquely elaborates a group of dihydrogenated ergot alkaloids that are biosynthetic intermediates leading to the principal product dihydroergosin
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