14,676 research outputs found

    Charge Lattices and Consistency of 6D Supergravity

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    We extend the known consistency conditions on the low-energy theory of six-dimensional N = 1 supergravity. We review some facts about the theory of two-form gauge fields and conclude that the charge lattice Gamma for such a theory has to be self-dual. The Green-Schwarz anomaly cancellation conditions in the supergravity theory determine a sublattice of Gamma. The condition that this sublattice can be extended to a self-dual lattice Gamma leads to a strong constraint on theories that otherwise appear to be self-consistent.Comment: 15 pages. v2: minor changes; references, additional example added; v3: minor corrections and clarifications added, JHEP versio

    Thermal effects on electron-phonon interaction in silicon nanostructures

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    Raman spectra from silicon nanostructures, recorded using excitation laser power density of 1.0 kW/cm^2, is employed here to reveal the dominance of thermal effects at temperatures higher than the room temperature. Room temperature Raman spectrum shows only phonon confinement and Fano effects. Raman spectra recorded at higher temperatures show increase in FWHM and decrease in asymmetry ratio with respect to its room temperature counterpart. Experimental Raman scattering data are analyzed successfully using theoretical Raman line-shape generated by incorporating the temperature dependence of phonon dispersion relation. Experimental and theoretical temperature dependent Raman spectra are in good agreement. Although quantum confinement and Fano effects persists, heating effects start dominating at higher temperatures than room tempaerature.Comment: 9 Pages, 3 Figures and 1 Tabl

    FooPar: A Functional Object Oriented Parallel Framework in Scala

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    We present FooPar, an extension for highly efficient Parallel Computing in the multi-paradigm programming language Scala. Scala offers concise and clean syntax and integrates functional programming features. Our framework FooPar combines these features with parallel computing techniques. FooPar is designed modular and supports easy access to different communication backends for distributed memory architectures as well as high performance math libraries. In this article we use it to parallelize matrix matrix multiplication and show its scalability by a isoefficiency analysis. In addition, results based on a empirical analysis on two supercomputers are given. We achieve close-to-optimal performance wrt. theoretical peak performance. Based on this result we conclude that FooPar allows to fully access Scala's design features without suffering from performance drops when compared to implementations purely based on C and MPI

    An In vitro comparadve evaluadon of a hand file and three rotary Nill Instruments for removing gutta percha during root canal re-treatment

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    Objective: To evaluate the efficacy of NITI mechanical rotary  instrumentation and Hedstrom file for gutta percha removal using dearing techniqueMethod: Forty extracted human single rooted premolar, each with a single canal were selected. The samples were decoronated to leave 17 mm root and Instrumented with K-flles upto MAF 30 using step back technique. Samples were obturated using cold lateral condensation of gutta-perdta and AH Plus sealer. The teeth were then randomly divided Into four groups of 10 specimens each. After 2 weeks all the canals were then retreated by either ProTaper re-treatment files, M--two re-treatment files, R-Endo re-treatment flies or Hedstrom flies. The amount of remaining filling materials after re-treatment procedures was assessed by  stereomlcroscope. Also time required for reaching original working length and for removal of obturating material (in min) was measured. Statistical analysis was accomplished using one way Kruskal-Wallls ANOVA and Mann-Whitney U testResult: M-two re-treatment flies showed least amount of gutta  perdta/sealer followed by Pro Taper re-treatment files, R-Endo  re-treatment flies and Hedstrom files.Conclusion: Under the experimental conditions, significant difference was observed between Pro Taper re-treatment flies&... Hedstrom flies and Mtwo re-treatment flies&... Hedstrom flies for gutta percha/sealer removal. Complete removal of materials did not occur with any of the instrument systems investigated.Keywords: Clearing technique, re-tteatment, rotary Instrument

    Global aspects of the space of 6D N = 1 supergravities

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    We perform a global analysis of the space of consistent 6D quantum gravity theories with N = 1 supersymmetry, including models with multiple tensor multiplets. We prove that for theories with fewer than T = 9 tensor multiplets, a finite number of distinct gauge groups and matter content are possible. We find infinite families of field combinations satisfying anomaly cancellation and admitting physical gauge kinetic terms for T > 8. We find an integral lattice associated with each apparently-consistent supergravity theory; this lattice is determined by the form of the anomaly polynomial. For models which can be realized in F-theory, this anomaly lattice is related to the intersection form on the base of the F-theory elliptic fibration. The condition that a supergravity model have an F-theory realization imposes constraints which can be expressed in terms of this lattice. The analysis of models which satisfy known low-energy consistency conditions and yet violate F-theory constraints suggests possible novel constraints on low-energy supergravity theories.Comment: 41 pages, 1 figur

    Visualising apoptosis in live zebrafish using fluorescence lifetime imaging with optical projection tomography to map FRET biosensor activity in space and time

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    Fluorescence lifetime imaging (FLIM) combined with optical projection tomography (OPT) has the potential to map Förster resonant energy transfer (FRET) readouts in space and time in intact transparent or near transparent live organisms such as zebrafish larvae, thereby providing a means to visualise cell signalling processes in their physiological context. Here the first application of FLIM OPT to read out biological function in live transgenic zebrafish larvae using a genetically expressed FRET biosensor is reported. Apoptosis, or programmed cell death, is mapped in 3-D by imaging the activity of a FRET biosensor that is cleaved by Caspase 3, which is a key effector of apoptosis. Although apoptosis is a naturally occurring process during development, it can also be triggered in a variety of ways, including through gamma irradiation. FLIM OPT is shown here to enable apoptosis to be monitored over time, in live zebrafish larvae via changes in Caspase 3 activation following gamma irradiation at 24 hours post fertilisation. Significant apoptosis was observed at 3.5 hours post irradiation, predominantly in the head region

    Discovering sequential rental patterns by fleet tracking

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    © Springer International Publishing Switzerland 2015. As one of the most well-known methods on customer analysis, sequential pattern mining generally focuses on customer business transactions to discover their behaviors. However in the real-world rental industry, behaviors are usually linked to other factors in terms of actual equipment circumstance. Fleet tracking factors, such as location and usage, have been widely considered as important features to improve work performance and predict customer preferences. In this paper, we propose an innovative sequential pattern mining method to discover rental patterns by combining business transactions with the fleet tracking factors. A novel sequential pattern mining framework is designed to detect the effective items by utilizing both business transactions and fleet tracking information. Experimental results on real datasets testify the effectiveness of our approach

    Renal Agenesis in New Zealand White Rabbit

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    This report describes some cases of unilateral renal agenesis, a congenital anomaly, in a breeding colony of New Zealand white rabbits, detected on physical and necropsy examination. The cases show absence of one of the kidneys, without involvement of the other parts of the genitourinary system or any other part of the body. The animals exhibited no clinical sign of renal failure. Serum biochemical and urine analysis of the animals showed a decrease in specific gravity of the urine with slight increase in the blood urea with no marked changes in other blood and urine parameters
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