2,067 research outputs found

    WZW-like Action for Heterotic String Field Theory

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    We complete the construction of the Neveu-Schwarz sector of heterotic string field theory begun in hep-th/0406212 by giving a closed-form expression for the action and gauge transformations. Just as the Wess-Zumino-Witten (WZW) action for open superstring field theory can be constructed from pure-gauge fields in bosonic open string field theory, our heterotic string field theory action is constructed from pure-gauge fields in bosonic closed string field theory. The construction involves a simple alternative form of the WZW action which is consistent with the algebraic structures of closed string field theory.Comment: 22 pages, no figures, LaTeX2

    Nematoda - free living

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    The list was compiled by Guy De Smet, a non-specialist, who was assisted by nematologists Magda Vincx, Ann Vanreusel, Sandra Vanhove, Jan Vanaverbeke and Maaike Steyaert. Dr. F. Riemann gave useful advice for the genus Daptonema. The classification in the list is based upon Lorenzen (1979, 1994). Information on the geographic distribution in the list is based upon Gerlach and Riemann (1973, 1974), Platt and Warwick (1983, 1988) and Warwick et al. (1998).ReferencesLorenzen, S. Entwürf eines Phylogenetischen Systems der Freilebenden Nematoden, Kiel, 1979.Lorenzen, S. The Phylogenetic Systematics of Freeliving Nematodes, The Ray Society, 1994.Gerlach, S. A. and Riemann, F. The Bremerhaven Checklist of Aquatic Nematodes. Veröffentlichungen des Instituts für Meeresforschung in Bremerhaven, Supplement 4, (Heft 1 1973, Heft 2 1974).Platt, H. M. and Warwick, R. M. Free-living Marine Nematodes (Part I British Enoplids) Synopses of the British Fauna (New series) No. 28, 1983.Platt, H. M. and Warwick, R. M. Free-living Marine Nematodes (Part II British Chromadorids) Synopses of the British Fauna (New series) No. 38, 1988.Warwick, R. M., Platt, H. M. and Somerfield, P. J. Free-living Marine Nematodes (Part III Monhysterids) Synopses of the British Fauna (New series) No. 53, 1998.</ul

    Spinor classification of the Weyl tensor in five dimensions

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    We investigate the spinor classification of the Weyl tensor in five dimensions due to De Smet. We show that a previously overlooked reality condition reduces the number of possible types in the classification. We classify all vacuum solutions belonging to the most special algebraic type. The connection between this spinor and the tensor classification due to Coley, Milson, Pravda and Pravdov\'a is investigated and the relation between most of the types in each of the classifications is given. We show that the black ring is algebraically general in the spinor classification.Comment: 40 page

    Rolling Closed String Tachyons and the Big Crunch

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    We study the low-energy effective field equations that couple gravity, the dilaton, and the bulk closed string tachyon of bosonic closed string theory. We establish that whenever the tachyon induces the rolling process, the string metric remains fixed while the dilaton rolls to strong coupling. For negative definite potentials we show that this results in an Einstein metric that crunches the universe in finite time. This behavior is shown to be rather generic even if the potentials are not negative definite. The solutions are reminiscent of those in the collapse stage of a cyclic universe cosmology where scalar field potentials with negative energies play a central role.Comment: 13 pages, 2 figures, LaTeX. Replaced version: one reference adde

    The Kerr-Newman-Godel Black Hole

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    By applying a set of Hassan-Sen transformations and string dualities to the Kerr-Godel solution of minimal D=5 supergravity we derive a four parameter family of five dimensional solutions in type II string theory. They describe rotating, charged black holes in a rotating background. For zero background rotation, the solution is D=5 Kerr-Newman; for zero charge it is Kerr-Godel. In a particular extremal limit the solution describes an asymptotically Godel BMPV black hole.Comment: 12 pages, LaTeX, no figures; v2: one reference added, very minor changes; to appear in CQ

    Selective digestive and oropharyngeal decontamination in medical and surgical ICU patients:individual patient data meta-analysis

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    Objectives: Selective digestive decontamination (SDD) and selective oropharyngeal decontamination (SOD) improved intensive care unit (ICU), hospital and 28-day survival in ICUs with low levels of antibiotic resistance. Yet it is unclear whether the effect differs between medical and surgical ICU patients.& para;& para;Methods: In an individual patient data meta-analysis, we systematically searched PubMed and included all randomized controlled studies published since 2000. We performed a two-stage meta-analysis with separate logistic regression models per study and per outcome (hospital survival and ICU survival) and subsequent pooling of main and interaction effects.& para;& para;Results: Six studies, all performed in countries with low levels of antibiotic resistance, yielded 16 528 hospital admissions and 17 884 ICU admissions for complete case analysis. Compared to standard care or placebo, the pooled adjusted odds ratios for hospital mortality was 0.82 (95% confidence interval (CI) 0.72-0.93) for SDD and 0.84 (95% CI 0.73-0.97) for SOD. Compared to SOD, the adjusted odds ratio for hospital mortality was 0.90 (95% CI 0.82-0.97) for SDD. The effects on hospital mortality were not modified by type of ICU admission (p values for interaction terms were 0.66 for SDD and control, 0.87 for SOD and control and 0.47 for SDD and SOD). Similar results were found for ICU mortality.& para;& para;Conclusions: In ICUs with low levels of antibiotic resistance, the effectiveness of SDD and SOD was not modified by type of ICU admission. SDD and SOD improved hospital and ICU survival compared to standard care in both patient populations, with SDD being more effective than SOD. (C) 2017 The Author(s). Published by Elsevier Ltd on behalf of European Society of Clinical Microbiology and Infectious Diseases

    Становлення та функціонування сучасних наукових шкіл

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    Background. Several studies have shown that the use of selective digestive tract decontamination (SDD) reduces mortality. However, fear for increasing multidrug resistance might prevent wide acceptance. A survey was performed among the units registered in the European Registry for Intensive Care (ERIC), in order to investigate the number of ICUs using SDD and the factors that prevented the use of SDD. Methods. One invitation to the electronic survey was sent to each ERIC unit. The survey focused on department characteristics (intensive care type, local resistance levels), local treatment modalities (antibiotic stewardship) and doctors' opinions (collaborative issues concerning SDD). All ICU's in countries participating in the European Centre for Disease Prevention and Control resistance surveillance program were analysed. Results. Seventeen percent of the ICUs registered in the ERIC database used SDD prophylaxis. Most of these ICUs were located in the Netherlands or Germany. ICUs using SDD were four times more likely to use antibiotic stewardship. Also larger ICUs were more likely to use SDD. On the contrary, resistance to antibiotics was not related to the use of SDD. Also the doctor's opinion that SDD is proven in duster-randomized trials was not a determinant for not using SDD. Conclusion. SDD is used in a minority of the European ICUs registered in the ERIC database. Larger ICUs and ICUs with a prudent antibiotic policy were more likely to use SDD. Neither antibiotic resistance nor the duster randomized study design were determinants of the non-use of SDD

    Cosmological tachyon from cubic string field theory

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    The classical dynamics of the tachyon scalar field of cubic string field theory is considered on a cosmological background. Starting from a nonlocal action with arbitrary tachyon potential, which encodes the bosonic and several supersymmetric cases, we study the equations of motion in the Hamilton-Jacobi formalism and with a generalized Friedmann equation, appliable in braneworld or modified gravity models. The cases of cubic (bosonic) and quartic (supersymmetric) tachyon potential in general relativity are automatically included. We comment the validity of the slow-roll approximation, the stability of the cosmological perturbations, and the relation between this tachyon and the Dirac-Born-Infeld one.Comment: 20 pages JHEP style, 1 figure; v4: misprints corrected, matches the published versio

    Tachyon Couplings to Fermion

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    By fixing the internal CP factor of tachyon and massless Ramond vertex operators in different pictures, we have shown that the internal CP factor of the disk level S-matrix elements of two fermions and odd number of tachyon vertex operators in the world volume of non-BPS D-branes/D-brane-anti-D-brane is zero. We have calculated the S-matrix element of two fermions and two tachyons which has non vanishing internal CP factor, and found the momentum expansion of this amplitude. In the abelian case, we have compared the two-fermion-two-tachyon coupling at low energy with the corresponding coupling in the gauge-fixed supersymmetric tachyon DBI action. The couplings in the two cases are exactly the same.Comment: 16 pages, latex file; V2:a missing term in the modified tachyon DBI action adde
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