The quantum probability ranking principle for information retrieval

While the Probability Ranking Principle for Information Retrieval provides the basis for formal models, it makes a very strong assumption regarding the dependence between documents. However, it has been observed that in real situations this assumption does not always hold. In this paper we propose a reformulation of the Probability Ranking Principle based on quantum theory. Quantum probability theory naturally includes interference effects between events. We posit that this interference captures the dependency between the judgement of document relevance. The outcome is a more sophisticated principle, the Quantum Probability Ranking Principle, that provides a more sensitive ranking which caters for interference/dependence between documents’ relevanc

Using the quantum probability ranking principle to rank interdependent documents

A known limitation of the Probability Ranking Principle (PRP) is that it does not cater for dependence between documents. Recently, the Quantum Probability Ranking Principle (QPRP) has been proposed, which implicitly captures dependencies between documents through “quantum interference”. This paper explores whether this new ranking principle leads to improved performance for subtopic retrieval, where novelty and diversity is required. In a thorough empirical investigation, models based on the PRP, as well as other recently proposed ranking strategies for subtopic retrieval (i.e. Maximal Marginal Relevance (MMR) and Portfolio Theory(PT)), are compared against the QPRP. On the given task, it is shown that the QPRP outperforms these other ranking strategies. And unlike MMR and PT, one of the main advantages of the QPRP is that no parameter estimation/tuning is required; making the QPRP both simple and effective. This research demonstrates that the application of quantum theory to problems within information retrieval can lead to significant improvements

Conformal Higher Spin Symmetries of 4d Massless Supermultiplets and osp(L,2M)osp(L,2M) Invariant Equations in Generalized (Super)Space

Realization of the conformal higher spin symmetry on the 4d massless field supermultiplets is given. The self-conjugated supermultiplets, including the linearized ${\cal N}=4$ SYM theory, are considered in some detail. Duality between non-unitary field-theoretical representations and the unitary doubleton--type representations of the 4d conformal algebra $su(2,2)$ is formulated in terms of a Bogolyubov transform. The set of 4d massless fields of all spins is shown to form a representation of $sp(8)$. The obtained results are extended to the generalized superspace invariant under $osp(L, 2M)$ supersymmetries. World line particle interpretation of the free higher spin theories in the $osp(2\N, 2M)$ invariant (super)space is given. Compatible with unitarity free equations of motion in the $osp(L,2M)$ invariant (super)space are formulated. A conjecture on the chain of $AdS_{d+1}/CFT_d \to AdS_{d}/CFT_{d-1} \to ...$ dualities in the higher spin gauge theories is proposed.Comment: Latex, 63 pages; no figures.V2 Typos corrected, References updated. V3.Typos correced, references and an explanation on the relationship with previous work in section 4 are added. The version to appear in Phys.Rev.

Development of a clot-targeted anticoagulant

The effectiveness of anticoagulant therapy is limited by the inability of many anticoagulant molecules to inhibit completely clot bound thrombin. Despite the development of direct, potent thrombin inhibitors such as hirudin, there remains significant opportunity to improve the treatment efficacy. Research in this area has provided evidence to indicate that the failure of existing anticoagulant therapies is due to the procoagulant nature of the clot itself. Clot-targeted anticoagulants offer the potential to: (1) simplify the administration methods; (2) reduce the quantity required for treatment, thus reducing the potential cost of treatment; (3) increase the local therapeutic concentration and (4) to prevent systemic side-effects. A model system has been developed for preparation of targeted anticoagulants using avidin and biotin for coupling. The Fab fragment of the monoclonal antibody DD3B6/22 which binds to the D-dimer component of cross-linked fibrin was prepared and conjugated to avidin. This conjugate was then reacted with the biotinylated specific active site thrombin inhibitor, biotin-PPACK (D-Phe-Pro-Arg-chloromethyl ketone). This targeted anticoagulant (TAC) molecule retained both the ability to bind D-dimer and inhibit thrombin. The reagent binds clots prepared in vitro, which correlates well with the good binding properties observed in an in vivo imaging trial carried out with DD3B6/22. The inhibition of clot procoagulant activity by the TAC reagent versus conventional inhibitors, biotin-PPACK, PPACK and hirudin was assessed in an in vitro assay developed in this study. Clots were pretreated with inhibitor and then thoroughly washed before the procoagulant activity was assayed. The TAC reagent was able to inhibit 90% of the procoagulant activity whereas the conventional inhibitors were only able to inhibit a maximum of 60%. This novel approach to targeting biological active molecules to the clot surface could be extended to include lytic agents or other anticoagulant molecules