1,149 research outputs found

    Non-perturbative calculations for the effective potential of the PTPT symmetric and non-Hermitian (−gϕ4)(-g\phi^{4}) field theoretic model

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    We investigate the effective potential of the PTPT symmetric (−gϕ4)(-g\phi^{4}) field theory, perturbatively as well as non-perturbatively. For the perturbative calculations, we first use normal ordering to obtain the first order effective potential from which the predicted vacuum condensate vanishes exponentially as G→G+G\to G^+ in agreement with previous calculations. For the higher orders, we employed the invariance of the bare parameters under the change of the mass scale tt to fix the transformed form totally equivalent to the original theory. The form so obtained up to G3G^3 is new and shows that all the 1PI amplitudes are perurbative for both Gâ‰Ș1G\ll 1 and G≫1G\gg 1 regions. For the intermediate region, we modified the fractal self-similar resummation method to have a unique resummation formula for all GG values. This unique formula is necessary because the effective potential is the generating functional for all the 1PI amplitudes which can be obtained via ∂nE/∂bn\partial^n E/\partial b^n and thus we can obtain an analytic calculation for the 1PI amplitudes. Again, the resummed from of the effective potential is new and interpolates the effective potential between the perturbative regions. Moreover, the resummed effective potential agrees in spirit of previous calculation concerning bound states.Comment: 20 page

    The Physical, Chemical and Biological Effects of Crude Oil Spills on Black Spruce Forest, Interior Alaska

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    ... The overall objectives of the study were threefold: 1) To detail the physical effects of crude oil spills in black spruce forests of interior Alaska emphasizing the mode of transport, area of impact vs. time and effects on the active layer and underlying permafrost; 2) To determine the fate of petroleum contaminants once spilled in subarctic terrestrial environments; 3) To evaluate the effects of crude oil spills on vegetation. ..

    Controlling Factors Determining The Selective Hscn Addition To Double Bonds And Their Application To The Synthesis Of 7-isothiocyano-7,8-α-dihydro-bisabolene

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    The reactivity of terminal and trisubstituted double bonds of monoterpenes with HSCN has been examined by GC giving evidence that kinetics is responsible for the chemoselective addition to terminal double bonds in terpenes. The results show that the addition to the terminal double bond is about 17 times faster than for trisubstituted double bonds and that the presence of the first SCN group in the molecule prevents a second addition. The presence of a hydroxyl or methoxy group in the molecule, decreases the reaction kinetics. Based on these kinetic experiments a two steps synthesis of the natural product 7-isothiocyano-7,8-dihydro-α-bisabolene using bisabolol as starting material, was planned and successfully accomplished.125661666Drobnica, L., KristĂ­an, P., AugustĂ­n, J., The Chemistry of the Cyanates and Their Thio Derivatives, , Saul Patai Ed., John Wiley & Sons, New YorkEdenborough, M.S., Herbert, R.B., (1988) Nat. Prod., p. 229Faulkner, D.J., (1994) Nat. Prod., p. 355(1993) Nat. Prod., p. 497(1992) Nat. Prod., p. 323(1991) Nat. Prod., p. 97(1990) Nat. Prod., p. 269(1988) Nat. Prod., p. 613Fraga, B.M., (1994) Nat. Prod. Rep., p. 533Piers, E., Young, B.W.A., Rettig, S.J., (1987) Tetrahedron, 43 (23), p. 5521Piers, E., Yeung, B.W., (1986) Can. J. Chem., 64, p. 2475Chenera, B., Chuang, C.P., Hart, D.J., Lai, C.S., (1992) J. Org. Chem., 57, p. 2018Da Silva, C.C., Almagro, V., Zukerman-Schpector, J., Castellano, E.E., Marsaioli, A.J., (1994) J. Org. Chem., 59, p. 2880Da Silva, C.C., Almagro, V., Marsaioli, A.J., (1993) Tetrahedron Lett., 34, p. 6717Martin, V.S., Woodward, S.S., Katsuki, T., Yamada, Y., Ikeda, M., Sharpless, K.B., (1981) J. Am. Chem. Soc., 103, p. 6237Rakels, J.L., Straathof, A.J.J., Heijnin, J.J., (1993) Enzyme Microb. Technol, 15, p. 1051Diveley, W.R., Buntin, G.A., (1969) J. Org. Chem., 34, p. 616Queiroga, C.L., Ferracini, V.L., Marsaioli, A.J., (1996) Phytochemistry, 42, p. 1097(-)Bisabolol (8) [(αS, 1S)-1-methanol-α,4-dimethyl-α-4-methyl-3-pentenyl-3-cyclohexene] was obtained from commercial candeia oil (CITRÓLEO - S.Paulo, SP, Brazil)Sullivan, B.W., Faulkner, D.J., Okamoto, K.T., Chen, M.H.M., Clardy, J., (1986) J. Org. Chem., 51, p. 5134Dubois, J.E., Lomas, J.S., (1971) Tetrahedron Lett., 7, p. 599Delay, F., Ohloff, F., (1979) Helv. Chem. Acta, 62, p. 326A sample of dihydrolimonene was kindly provided by Prof. Marcio C. S. de Mattos from IQ/UFRJ, RJ, Brazi

    A concise review on multi-omics data integration for terroir analysis in Vitis vinifera

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    Mini reviewVitis vinifera (grapevine) is one of the most important fruit crops, both for fresh consumption and wine and spirit production. The term terroir is frequently used in viticulture and the wine industry to relate wine sensory attributes to its geographic origin. Although, it can be cultivated in a wide range of environments, differences in growing conditions have a significant impact on fruit traits that ultimately affect wine quality. Understanding how fruit quality and yield are controlled at a molecular level in grapevine in response to environmental cues has been a major driver of research. Advances in the area of genomics, epigenomics, transcriptomics, proteomics and metabolomics, have significantly increased our knowledge on the abiotic regulation of yield and quality in many crop species, including V. vinifera. The integrated analysis of multiple ‘omics’ can give us the opportunity to better understand how plants modulate their response to different environments. However, ‘omics’ technologies provide a large amount of biological data and its interpretation is not always straightforward, especially when different ‘omic’ results are combined. Here we examine the current strategies used to integrate multi-omics, and how these have been used in V. vinifera. In addition, we also discuss the importance of including epigenomics data when integrating omics data as epigenetic mechanisms could play a major role as an intermediary between the environment and the genome.Pastor Jullian Fabres, Cassandra Collins, Timothy R. Cavagnaro and Carlos M. Rodríguez Lópe

    The holy blood and the holy grail: Myths of scientific racism and the pursuit of excellence in sport

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    Despite the continuing publication of research that suggests there is no scientific basis to 'race' as a biological category, theories of racial difference continue to be invoked within sport to explain the perceived dominance of black athletes. In the case of John Entine's controversial 'Taboo: why black athletes dominate sports and why we are afraid to talk about it' or undergraduate textbooks that suggest 'racial differences' in physique may significantly affect athletic performance, scientific racism is normalised in sport. In this article, the relationship between scientific racism and sport will be examined. Qualitative research with current sport scientists is used to investigate the socio-ethical tensions within the subject field of sport science between professionalism, scientism and the demand from external interests to produce results that help people in sport win medals. It will be shown that these tensions, combined with the history of race as a category in sport science, combine to create the discourse of scientific knowledge that reflects, rather than challenges, folk genetics of black athletic physicality

    Supermassive Binaries and Extragalactic Jets

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    Some quasars show Doppler shifted broad emission line peaks. I give new statistics of the occurrence of these peaks and show that, while the most spectacular cases are in quasars with strong radio jets inclined to the line of sight, they are also almost as common in radio-quiet quasars. Theories of the origin of the peaks are reviewed and it is argued that the displaced peaks are most likely produced by the supermassive binary model. The separations of the peaks in the 3C 390.3-type objects are consistent with orientation-dependent "unified models" of quasar activity. If the supermassive binary model is correct, all members of "the jet set" (astrophysical objects showing jets) could be binaries.Comment: 31 pages, PostScript, missing figure is in ApJ 464, L105 (see http://www.aas.org/ApJ/v464n2/5736/5736.html

    The directed flow maximum near c_s=0

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    We investigate the excitation function of quark-gluon plasma formation and of directed in-plane flow of nucleons in the energy range of the BNL-AGS and for the E(Lab)=40AGeV Pb+Pb collisions performed recently at the CERN-SPS. We employ the three-fluid model with dynamical unification of kinetically equilibrated fluid elements. Within our model with first-order phase transition at high density, droplets of QGP coexisting with hadronic matter are produced already at BNL-AGS energies, E(Lab)=10AGeV. A substantial decrease of the isentropic velocity of sound, however, requires higher energies, E(Lab)=40AGeV. We show the effect on the flow of nucleons in the reaction plane. According to our model calculations, kinematic requirements and EoS effects work hand-in-hand at E(Lab)=40AGeV to allow the observation of the dropping velocity of sound via an increase of the directed flow around midrapidity as compared to top BNL-AGS energy.Comment: 10 pages, 4 figures; plot of p(e) at various specific entropies shows why mixed phase is not soft at AGS energ

    Renormalization of composite operators

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    The blocked composite operators are defined in the one-component Euclidean scalar field theory, and shown to generate a linear transformation of the operators, the operator mixing. This transformation allows us to introduce the parallel transport of the operators along the RG trajectory. The connection on this one-dimensional manifold governs the scale evolution of the operator mixing. It is shown that the solution of the eigenvalue problem of the connection gives the various scaling regimes and the relevant operators there. The relation to perturbative renormalization is also discussed in the framework of the ϕ3\phi^3 theory in dimension d=6d=6.Comment: 24 pages, revtex (accepted by Phys. Rev. D), changes in introduction and summar
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