71 research outputs found

    Intrinsic Geometric Structure of c=−2c=-2 Quantum Gravity

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    We couple c=-2 matter to 2-dimensional gravity within the framework of dynamical triangulations. We use a very fast algorithm, special to the c=-2 case, in order to test scaling of correlation functions defined in terms of geodesic distance and we determine the fractal dimension d_H with high accuracy. We find d_H=3.58(4), consistent with a prediction coming from the study of diffusion in the context of Liouville theory, and that the quantum space-time possesses the same fractal properties at all distance scales similarly to the case of pure gravity

    The quantum space-time of c=-2 gravity

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    We study the fractal structure of space-time of two-dimensional quantum gravity coupled to c=-2 conformal matter by means of computer simulations. We find that the intrinsic Hausdorff dimension d_H = 3.58 +/- 0.04. This result supports the conjecture d_H = -2 \alpha_1/\alpha_{-1}, where \alpha_n is the gravitational dressing exponent of a spinless primary field of conformal weight (n+1,n+1), and it disfavours the alternative prediction d_H = 2/|\gamma|. On the other hand ~ r^{2n} for n>1 with good accuracy, i.e. the boundary length l has an anomalous dimension relative to the area of the surface.Comment: 46 pages, 16 figures, 32 eps files, using psfig.sty and epsf.st

    Numerical study for the c-dependence of fractal dimension in two-dimensional quantum gravity

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    We numerically investigate the fractal structure of two-dimensional quantum gravity coupled to matter central charge c for −2≤c≤1-2 \leq c \leq 1. We reformulate Q-state Potts model into the model which can be identified as a weighted percolation cluster model and can make continuous change of Q, which relates c, on the dynamically triangulated lattice. The c-dependence of the critical coupling is measured from the percolation probability and susceptibility. The c-dependence of the string susceptibility of the quantum surface is evaluated and has very good agreement with the theoretical predictions. The c-dependence of the fractal dimension based on the finite size scaling hypothesis is measured and has excellent agreement with one of the theoretical predictions previously proposed except for the region near c≈1c\approx 1.Comment: 41 pages, 16 figure

    In vitro genotoxicity and cytotoxicity of a particular combination of pemetrexed and cefixime in human peripheral blood lymphocytes

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    This study aims to find the genotoxic and cytotoxic effects of a particular combination of pemetrexed (PMX) and cefixime (CFX) in human peripheral blood lymphocytes. Chromosome aberration (CA), sister chromatid exchange (SCE), and micronucleus (MN) tests were used to assess genotoxicity. Whereas, the cytotoxicity was evaluated by using mitotic index (MI), proliferation index (PI), and nuclear division index (NDI). Our tests were proceeded with concentrations of 12.5 + 450, 25 + 800, 37.5 + 1150, and 50 + 1500 μg/mL of a mixture of PMX and CFX separately for 24 hr and 48 hr. The combination of PMX + CFX did not induce the CA or SCE in human peripheral blood lymphocytes when compared with both the control and the solvent control. MN in human peripheral blood lymphocytes was not significantly increased after treatment with a particular combination of PMX + CFX. However, PMX + CFX significantly decreased the MI, PI and NDI at all concentrations for 24- and 48-hr treatment periods when compared with both controls. Generally, PMX + CFX inhibited cell proliferation more than positive control (MMC) and showed a higher cytotoxic effect than MMC at both treatment periods. These results were compared with individual effects of PMX and CFX. As a result, it was observed that a particular combination of PMX + CFX was not genotoxic. However, the combination synergistically increase cytotoxicity in human peripheral blood lymphocytes. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s40064-015-0803-3) contains supplementary material, which is available to authorized users

    Ester-Amide Exchange Reactions Using 2-Pyridone derivatives as Tautomeric Catalysts

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    The application of 2-pyridone as a tautomeric catalyst for ester-amide exchange reactions was investigated. This compound was found to be most effective at accelerating these reactions when 4-nitrophenyl acetate was used as an acylating agent in toluene. Primary amines without branching at the α-position were determined to be the most suitable substrates. Various 2-pyridone derivatives having an electron-donating group at the 5-position (including methoxy and pirrolidino groups) exhibited superior performance. Acylation reactions of mixtures of primary and secondary amines preferentially acylated the latter compounds in the absence of a catalyst or with N,N-dimethylaminopyridine (DMAP) as the catalyst, whereas primary amines were acylated in the case that a 2-pyridone derivative with a pirrolidino group was employed. The reaction mechanism associated with this preferential acylation process was evaluated and is discussed herein
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