153 research outputs found

    Matrix Theory for the DLCQ of Type IIB String Theory on the AdS/Plane-wave

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    We propose a recipe to construct the DLCQ Hamiltonian of type IIB string theory on the AdS (and/or plane-wave) background. We consider a system of J number of coincident unstable non-BPS D0-branes of IIB theory in the light-cone gauge and on the plane-wave background with a compact null direction, the dynamics of which is described by the world-line U(J) gauge theory. This configuration suffers from tachyonic instabilities. Having instabilities been cured through the process of open string tachyon condensation, by expanding the theory about true minima of the effective potential and furthermore taking low energy limit to decouple the heavy modes, we end up with a 0+1-dimensional supersymmetric U(J) gauge theory, a Matrix Theory. We conjecture that the Hamiltonian of this Matrix Theory is just the DLCQ Hamiltonian of type IIB string theory on the AdS or equivalently plane-wave background in a sector with J units of light-cone momentum. We present some pieces of evidence in support of the proposal.Comment: LaTeX, 35 pages, 2 eps figures; v2: minor changes, references added; v3: minor change

    Electron Currents from Gradual Heating in Tilted Dirac Cone Materials

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    Materials hosting tilted Dirac/Weyl fermions upgrade the solid-state phenomena into a new spacetime structure. They admit a geometric description in terms of an effective spacetime metric. Using this metric that is rooted in the long-distance behavior of the underlying lattice, we formulate the hydrodynamics theory for tilted Dirac/Weyl materials in 2+12+1 spacetime dimensions. We find that the mingling of space and time through the off-diagonal components of the metric gives rise to: (i) heat and electric currents proportional to the "temporal" gradient of temperature, tT\partial_t T and (ii) a non-zero Hall conductance σijζiζj\sigma^{ij}\propto \zeta^i\zeta^j where ζj\zeta^j parametrizes the tilt in jj'th space direction. The finding (i) above that can be demonstrated in the laboratory, suggests that thanks to the non-trivial spacetime geometry in these materials, naturally available sources of tT\partial_t T in hot deserts offer a new concept for the conversion of sunlight heating into electric energy. We further find a tilt-induced non-Drude contribution to conductivity which can be experimentally disentangled from the usual Drude pole

    Swampland de Sitter conjectures in no-scale supergravity models

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    It is challenging to construct explicit and controllable models that realize de Sitter solutions in string compactifications. This difficulty is the main motivation for the refined de Sitter conjecture and the trans-Planckian censorship conjecture which forbid stable de Sitter solutions but allow metastable, unstable and rolling solutions in a theory consistent with quantum gravity. Inspired by this, we first study a toy de Sitter no-scale supergravity model and show that for particular choices of parameters it can be consistent with the refined de Sitter conjecture and the trans-Planckian censorship conjecture. Then we modify the model by adding rolling dynamics and show that the theory can become stable along the imaginary direction, where it would otherwise be unstable. We extend the model to multifield rolling and de Sitter fields, finding the parameter space where they can be compatible with the refined de Sitter conjecture. The modified models with rolling fields can be used to construct quintessence models to accommodate the accelerating expansion of the Universe.publishedVersio

    Hydrodynamics and the Detection of the QCD Axial Anomaly in Heavy Ion Collisions

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    We consider the experimental implications of the axial current triangle diagram anomaly in a hydrodynamic description of high density QCD. We propose a signal of an enhanced production of spin-excited hadrons in the direction of the rotation axis in off-central heavy ion collisions.Comment: 15 pages, 19 figures; v2: refs added, minor changes to the plots; v3, comments adde

    The Relation between Self-Citation and Impact Factor in Medical Science Open Access Journals in ISI & DOAJ Databases

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    Citation is one of the important elements in scientific literature which has a significant role in information production and generation. Self-citation is a part of citation behavior. Relying on their articles, journals can change the number of citations and consequently the level of journal impact factor. This research aims at investigating the relation between self-citation and impact factor in the open access journals indexed in ISI and DOAJ in medical science in 2007-08. In this research, indexes such as the relation between self-citation of journal and impact factor and the effect of self-citation rate of the journal in open access performance are investigated. Research method is an analytical method conducted by using citation analysis technique. SPSS statistical software was used to examine and analyze the data and its inferential analysis methods such as Pierson Factor were used as well. Statistical society includes 168 journals. The results showed a self-citation rate of 28% for the journal. The findings indicate that there is a significant relation between self-citation and impact factor. After omitting self-citation, the level of self-citation in the performance of journals showed that 60% of the titles in the medical science experienced ranking increase, 27% experienced ranking decrease and 13% remained unchanged. Torabian R, Heidari A, Shahrifar M, Khodadi E, Esmaeile Vardanjani SA. The Relation between Self-Citation and Impact Factor in Medical Science Open Access Journals in ISI & DOAJ Databases. Life Sci J 2012;9(4):2206-2209] (ISSN: 1097-8135). http://www.lifesciencesite.com. 32

    Relativistic Hydrodynamics with General Anomalous Charges

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    We consider the hydrodynamic regime of gauge theories with general triangle anomalies, where the participating currents may be global or gauged, abelian or non-abelian. We generalize the argument of arXiv:0906.5044, and construct at the viscous order the stress-energy tensor, the charge currents and the entropy current.Comment: 13 pages, Revte

    Extensions of AdS_5 x S^5 and the Plane-wave Superalgebras and Their Realization in the Tiny Graviton Matrix Theory

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    In this paper we consider all consistent extensions of the AdS_5 x S^5 superalgebra, psu(2,2|4), to incorporate brane charges by introducing both bosonic and fermionic (non)central extensions. We study the Inonu-Wigner contraction of the extended psu(2,2|4) under the Penrose limit to obtain the most general consistent extension of the plane-wave superalgebra and compare these extensions with the possible BPS (flat or spherical) brane configurations in the plane-wave background. We give an explicit realization of some of these extensions in terms of the Tiny Graviton Matrix Theory (TGMT)[hep-th/0406214] which is the 0+1 dimensional gauge theory conjectured to describe the DLCQ of strings on the AdS_5 x S^5 and/or the plane-wave background.Comment: 27 pages, LaTe

    SDII Building Archetype Design v1.0

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    Building archetypes are fundamental to exploring and demonstrating the seismic behavior of modern structures. No suitable archetypes or prototypes exist in the open literature that focus on steel deck diaphragms for conventional steel buildings. Three dimensional building analysis, with meaningful contributions from the diaphragm in terms of behavior, has not formed the basis for modern seismic standards in steel at this time. The objectives for the SDII building archetypes include the following. Develop a series of 3D steel-framed archetype buildings that explore and document the design of horizontal lateral force resisting systems (LFRSs) with steel deck-based diaphragms as well as vertical LFRSs and the inter-relationship between the two. Provide a series of buildings that form a common basis of comparison for diaphragms in steel-framed buildings much the same way the SAC buildings did for the vertical LFRS. Explicitly explore the impact of the ASCE 7-16 standard, and ASCE 7-16 alternate diaphragm design with Rs=1 and Rs=3 in designs. Inform areas for needed experimentation, and create targets for advancing nonlinear analysis within the full SDII effort. Version 1.0 of this archetype effort includes: (1) a complete slide deck explaining the design of a 12 story steel building archetype using buckling restrained braced (BRB) frames for the vertical LFRS and steel deck with fill for the diaphragm/horizontal LFRS detailed to the ASCE7-16 standard as well as the ASCE7-16 alternate diaphragm provisions with Rs=1 and Rs=3, (2) a series of spreadsheets that provide the complete design calculations for the gravity and lateral systems, (3) a series of computer models (using the SAP structural analysis program), and (4) a literature review of other related building archetypes and justification for developing new building archetypes. (This version has been superseded by v2.0 - see http://jhir.library.jhu.edu/handle/1774.2/62106)American Institute of Steel Construction (AISC), American Iron and Steel Institute (AISI), Steel Deck Institute (SDI), Steel Joist Institute (SJI), Metal Building Manufacturers Association (MBMA), National Science Foundation (NSF

    A portable system for processing donated whole blood into high quality components without centrifugation

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    Background The use of centrifugation-based approaches for processing donated blood into components is routine in the industrialized world, as disparate storage conditions require the rapid separation of ‘whole blood’ into distinct red blood cell (RBC), platelet, and plasma products. However, the logistical complications and potential cellular damage associated with centrifugation/apheresis manufacturing of blood products are well documented. The objective of this study was to evaluate a proof-of-concept system for whole blood processing, which does not employ electromechanical parts, is easily portable, and can be operated immediately after donation with minimal human labor. Methods and findings In a split-unit study (n = 6), full (~500mL) units of freshly-donated whole blood were divided, with one half processed by conventional centrifugation techniques and the other with the new blood separation system. Each of these processes took 2–3 hours to complete and were performed in parallel. Blood products generated by the two approaches were compared using an extensive panel of cellular and plasma quality metrics. Comparison of nearly all RBC parameters showed no significant differences between the two approaches, although the portable system generated RBC units with a slight but statistically significant improvement in 2,3-diphosphoglyceric acid concentration (p < 0.05). More notably, several markers of platelet damage were significantly and meaningfully higher in products generated with conventional centrifugation: the increase in platelet activation (assessed via P-selectin expression in platelets before and after blood processing) was nearly 4-fold higher for platelet units produced via centrifugation, and the release of pro-inflammatory mediators (soluble CD40-ligand, thromboxane B2) was significantly higher for centrifuged platelets as well (p < 0.01). Conclusion This study demonstrated that a simple, passive system for separating donated blood into components may be a viable alternative to centrifugation—particularly for applications in remote or resource-limited settings, or for patients requiring highly functional platelet product
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