23,407 research outputs found

    Complex copula systems as suppletive alomorphy

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    Languages are known to vary in the number of verbs they exhibit corresponding to English "be", in the distribution of such copular verbs, and in the presence or absence of a distinct verb for possession sentences corresponding to English "have". This paper offers novel arguments for the position that such differences should be modeled in terms of suppletive allomorphy of the same syntactic element (here dubbed v BE), employing a Late Insertion- based framework. It is shown that such a suppletive allomorphy approach to complex copula systems makes three predictions that distinguish it from non-suppletion-based alternatives (concerning decomposition, possible and impossible syncretisms, and Impoverishment), and that these predictions seem to be correct (although a full test of the possible and impossible syncretisms prediction is not possible in the current state of knowledge)

    Exploring attitudes towards a randomised controlled trial of venous access devices – a nested pre-trial qualitative study

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    Purpose: This pre-trial qualitative research study was carried out to explore patient and clinical staff attitudes to central venous access devices (CVADs). In addition, views about participation in a randomised controlled trial (RCT) were explored with the aim of maximising recruitment to an imminent RCT of three CVADs. Methods: Three patient focus groups (each comprising three patients) and 23 interviews with clinical staff were conducted. Interviews and focus group discussions were digitally recorded, transcribed verbatim, anonymised, uploaded to the QSR NVivo10 qualitative software programme and thematically analysed. Results: Analysis of focus group interviews revealed the added challenges that a CVAD poses to patients with cancer. Four key themes emerged: continuity of daily life, pain and discomfort, stigma (a mark of disgrace associated with certain conditions) and self-preservation. The findings show the impact of a CVAD on patients’ ability to manage their condition. Clinical staff interviews highlighted several potential barriers to recruitment; a lack of equipoise (genuine clinical uncertainty as to which intervention is the most beneficial), concerns about the logistics of device insertion and a perceived requirement for education and training. Conclusions: This qualitative study raises awareness of key areas of concern to patients who need a CVAD for chemotherapy delivery. It was identified that there is a need for clearer patient information around CVADs. Additionally it allows investigators to identify barriers to recruitment in a timely manner in order to minimise the potential for conflict between the roles of carer and researcher and consequently, maximise recruitment to the RCT

    USHER: an algorithm for particle insertion in dense fluids

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    The insertion of solvent particles in molecular dynamics simulations of complex fluids is required in many situations involving open systems, but this challenging task has been scarcely explored in the literature. We propose a simple and fast algorithm (USHER) that inserts the new solvent particles at locations where the potential energy has the desired prespecified value. For instance, this value may be set equal to the system's excess energy per particle, in such way that the inserted particles are energetically indistinguishable from the other particles present. During the search for the insertion site, the USHER algorithm uses a steepest descent iterator with a displacement whose magnitude is adapted to the local features of the energy landscape. The only adjustable parameter in the algorithm is the maximum displacement and we show that its optimal value can be extracted from an analysis of the structure of the potential energy landscape. We present insertion tests in periodic and non-periodic systems filled with a Lennard-Jones fluid whose density ranges from moderate values to high values.Comment: 10 pages (Latex), 8 figures (postscript); J. Chem. Phys. (in press) 200

    Open/Closed Topological CP1 Sigma Model Revisited

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    We consider the topological sigma-model on Riemann surfaces with genus g and h holes, and target space CP1. We calculate the correlation functions of bulk and boundary operators, and study the symmetries of the model and its most general deformation. We study the open/closed topological field theory (TFT) correspondence by summing up the boundaries. We argue that this summation can be understood as a renormalization of the closed TFT. We couple the model to topological gravity and derive constitutive relations between the correlation functions of bulk and boundary operators.Comment: 25 page

    Superstring field theory equivalence: Ramond sector

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    We prove that the finite gauge transformation of the Ramond sector of the modified cubic superstring field theory is ill-defined due to collisions of picture changing operators. Despite this problem we study to what extent could a bijective classical correspondence between this theory and the (presumably consistent) non-polynomial theory exist. We find that the classical equivalence between these two theories can almost be extended to the Ramond sector: We construct mappings between the string fields (NS and Ramond, including Chan-Paton factors and the various GSO sectors) of the two theories that send solutions to solutions in a way that respects the linearized gauge symmetries in both sides and keeps the action of the solutions invariant. The perturbative spectrum around equivalent solutions is also isomorphic. The problem with the cubic theory implies that the correspondence of the linearized gauge symmetries cannot be extended to a correspondence of the finite gauge symmetries. Hence, our equivalence is only formal, since it relates a consistent theory to an inconsistent one. Nonetheless, we believe that the fact that the equivalence formally works suggests that a consistent modification of the cubic theory exists. We construct a theory that can be considered as a first step towards a consistent RNS cubic theory.Comment: v1: 24 pages. v2: 27 pages, significant modifications of the presentation, new section, typos corrected, references adde

    POPE: Partial Order Preserving Encoding

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    Recently there has been much interest in performing search queries over encrypted data to enable functionality while protecting sensitive data. One particularly efficient mechanism for executing such queries is order-preserving encryption/encoding (OPE) which results in ciphertexts that preserve the relative order of the underlying plaintexts thus allowing range and comparison queries to be performed directly on ciphertexts. In this paper, we propose an alternative approach to range queries over encrypted data that is optimized to support insert-heavy workloads as are common in "big data" applications while still maintaining search functionality and achieving stronger security. Specifically, we propose a new primitive called partial order preserving encoding (POPE) that achieves ideal OPE security with frequency hiding and also leaves a sizable fraction of the data pairwise incomparable. Using only O(1) persistent and O(nϵ)O(n^\epsilon) non-persistent client storage for 0<ϵ<10<\epsilon<1, our POPE scheme provides extremely fast batch insertion consisting of a single round, and efficient search with O(1) amortized cost for up to O(n1−ϵ)O(n^{1-\epsilon}) search queries. This improved security and performance makes our scheme better suited for today's insert-heavy databases.Comment: Appears in ACM CCS 2016 Proceeding
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