1,637 research outputs found

    Big brother is watching - using digital disease surveillance tools for near real-time forecasting

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    Abstract for the International Journal of Infectious Diseases 79 (S1) (2019).https://www.ijidonline.com/article/S1201-9712(18)34659-9/abstractPublished versio

    Quaternionic and Octonionic Spinors. A Classification

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    Quaternionic and octonionic realizations of Clifford algebras and spinors are classified and explicitly constructed in terms of recursive formulas. The most general free dynamics in arbitrary signature space-times for both quaternionic and octonionic spinors is presented. In the octonionic case we further provide a systematic list of results and tables expressing, e.g., the relations of the octonionic Clifford algebras with the G2G_2 cosets over the Lorentz algebras, the identities satisfied by the higher-rank antisymmetric octonionic tensors and so on. Applications of these results range from the classification of octonionic generalized supersymmetries, the construction of octonionic superstrings, as well as the investigations concerning the recently discovered octonionic MM-superalgebra and its superconformal extension.Comment: 24 pages, LaTe

    Classification of irreps and invariants of the N-extended Supersymmetric Quantum Mechanics

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    We present an algorithmic classification of the irreps of the NN-extended one-dimensional supersymmetry algebra linearly realized on a finite number of fields. Our work is based on the 1-to-1 \cite{pt} correspondence between Weyl-type Clifford algebras (whose irreps are fully classified) and classes of irreps of the NN-extended 1D supersymmetry. The complete classification of irreps is presented up to N≀10N\leq 10. The fields of an irrep are accommodated in ll different spin states. N=10 is the minimal value admitting length l>4l>4 irreps. The classification of length-4 irreps of the N=12 and {\em real} N=11 extended supersymmetries is also explicitly presented.\par Tensoring irreps allows us to systematically construct manifestly (NN-extended) supersymmetric multi-linear invariants {\em without} introducing a superspace formalism. Multi-linear invariants can be constructed both for {\em unconstrained} and {\em multi-linearly constrained} fields. A whole class of off-shell invariant actions are produced in association with each irreducible representation. The explicit example of the N=8 off-shell action of the (1,8,7)(1,8,7) multiplet is presented.\par Tensoring zero-energy irreps leads us to the notion of the {\em fusion algebra} of the 1D NN-extended supersymmetric vacua.Comment: Final version to appear in JHEP. 52 pages. The part with the complete classification of irreps (and the explicit presentation of length-4 irreps of N=9,10,11,12 and N=10 length-5 irreps) is unchanged. An extra section has been added with an entire class of off-shell invariant actions for arbitrary values N of the 1D extended supersymmetry. A non-trivial N=8 off-shell action for the (1,8,7) multiplet has been constructed as an example. It is obtained in terms of the octonionic structure constant

    Hermitian versus holomorphic complex and quaternionic generalized supersymmetries of the M-theory. A classification

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    Relying upon the division-algebra classification of Clifford algebras and spinors, a classification of generalized supersymmetries (or, with a slight abuse of language,"generalized supertranslations") is provided. In each given space-time the maximal, saturated, generalized supersymmetry, compatible with the division-algebra constraint that can be consistently imposed on spinors and on superalgebra generators, is furnished. Constraining the superalgebra generators in both the complex and the quaternionic cases gives rise to the two classes of constrained hermitian and holomorphic generalized supersymmetries. In the complex case these two classes of generalized supersymmetries can be regarded as complementary. The quaternionic holomorphic supersymmetry only exists in certain space-time dimensions and can admit at most a single bosonic scalar central charge. The results here presented pave the way for a better understanding of the various MM algebra-type of structures which can be introduced in different space-time signatures and in association with different division algebras, as well as their mutual relations. In a previous work, e.g., the introduction of a complex holomorphic generalized supersymmetry was shown to be necessary in order to perform the analytic continuation of the standard MM-theory to the 11-dimensional Euclidean space. As an application of the present results, it is shown that the above algebra also admits a 12-dimensional, Euclidean, FF-algebra presentation.Comment: 25 pages, LaTe

    Satellite laser ranging work at the Goddard Space Flight Center

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    Laser ranging systems, their range and accuracy capabilities, and planned improvements for future systems are discussed, the systems include one fixed and two mobile lasers ranging systems. They have demonstrated better than 10 cm accuracy both on a carefully surveyed ground range and in regular satellite ranging operations. They are capable of ranging to all currently launched retroreflector equipped satellites with the exception of Timation III. A third mobile system is discussed which will be accurate to better than 5 cm and will be capable of ranging to distant satellites such as Timation III and LAGEOS

    Supersymmetric Rotating Black Holes and Causality Violation

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    The geodesics of the rotating extreme black hole in five spacetime dimensions found by Breckenridge, Myers, Peet and Vafa are Liouville integrable and may be integrated by additively separating the Hamilton-Jacobi equation. This allows us to obtain the St\"ackel-Killing tensor. We use these facts to give the maximal analytic extension of the spacetime and discuss some aspects of its causal structure. In particular, we exhibit a `repulson'-like behaviour occuring when there are naked closed timelike curves. In this case we find that the spacetime is geodesically complete (with respect to causal geodesics) and free of singularities. When a partial Cauchy surface exists, we show, by solving the Klein-Gordon equation, that the absorption cross-section for massless waves at small frequencies is given by the area of the hole. At high frequencies a dependence on the angular quantum numbers of the wave develops. We comment on some aspects of `inertial time travel' and argue that such time machines cannot be constructed by spinning up a black hole with no naked closed timelike curves.Comment: 36 pages,LaTeX,8 figures;added 1 reference and a few comments; formula (2.6) corrected; a few changes to section

    On Supergroups with Odd Clifford Parameters and Supersymmetry with Modified Leibniz Rule

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    We investigate supergroups with Grassmann parameters replaced by odd Clifford parameters. The connection with non-anticommutative supersymmetry is discussed. A Berezin-like calculus for odd Clifford variables is introduced. Fermionic covariant derivatives for supergroups with odd Clifford variables are derived. Applications to supersymmetric quantum mechanics are made. Deformations of the original supersymmetric theories are encountered when the fermionic covariant derivatives do not obey the graded Leibniz property. The simplest non-trivial example is given by the N=2 SQM with a real (1,2,1)(1,2,1) multiplet and a cubic potential. The action is real. Depending on the overall sign ("Euclidean" or "Lorentzian") of the deformation, a Bender-Boettcher pseudo-hermitian hamiltonian is encountered when solving the equation of motion of the auxiliary field. A possible connection of our framework with the Drinfeld twist deformation of supersymmetry is pointed out.Comment: Final version to be published in Int. J. Mod. Phys. A; 20 page

    The emergence of enterovirus D68 in England in autumn 2014 and the necessity for reinforcing enterovirus respiratory screening.

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    In autumn 2014, enterovirus D68 (EV-D68) cases presenting with severe respiratory or neurological disease were described in countries worldwide. To describe the epidemiology and virological characteristics of EV-D68 in England, we collected clinical information on laboratory-confirmed EV-D68 cases detected in secondary care (hospitals), between September 2014 and January 2015. In primary care (general practitioners), respiratory swabs collected (September 2013-January 2015) from patients presenting with influenza-like illness were tested for EV-D68. In secondary care 55 EV-D68 cases were detected. Among those, 45 cases had clinical information available and 89% (40/45) presented with severe respiratory symptoms. Detection of EV-D68 among patients in primary care increased from 0.4% (4/1074; 95% CI 0.1-1.0) (September 2013-January 2014) to 0.8% (11/1359; 95% CI 0.4-1.5) (September 2014-January 2015). Characterization of EV-D68 strains circulating in England since 2012 and up to winter 2014/2015 indicated that those strains were genetically similar to those detected in 2014 in USA. We recommend reinforcing enterovirus surveillance through screening respiratory samples of suspected cases

    Trauma histories of men and women in residential drug treatment: The Scottish evidence

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    This article focuses on self-reported child neglect and abuse in residential drug treatment drawing on data from clients in Scotland collected 1996-1999. It notes the lack of adoption of regular screening using validated tools of childhood trauma in men and women. The authors’ findings suggest that the prevalence of childhood abuse histories are higher in female drug users than male drug users but recognises that even with standardised tools there is a wealth of diverse categories of severity of abuse that warn against broad treatment plans for ‘the traumatised’
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