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We calculate the one-loop graviton vacuum polarization induced by a massless, nonminimally coupled scalar field on Minkowski background. We make use of the Schwinger-Keldysh formalism, which allows us to study time dependent phenomena. As an application we compute the leading quantum correction to the Newtonian potential of a point particle. The novel aspect of the calculation is the use of the Schwinger-Keldysh formalism, within which we calculate the time transients induced by switching on the graviton-scalar coupling. [ABSTRACT FROM AUTHOR]

The new pyrimidine derivatives of 2,3-O,O-dibenzyl-6-deoxy-l-ascorbic acid (8−10) were synthesized by condensation of uracil and its 5-fluoro- and 5-trifluoromethyl-substituted derivatives with 4-(5,6-epoxypropyl)-2,3-O,O-dibenzyl-l-ascorbic acid (7), while pyrimidine derivatives of 4,5-didehydro-5,6-dideoxy-l-ascorbic acid (14−17) with free C-2‘ and C-3‘ hydroxy groups in the lactone ring were obtained by debenzylation of 11−13 with boron trichloride. Z-Configuration of the C4‘&dbd;C5‘ double bond and position of the benzyl group in the lactone ring of 14 were deduced from their ¹H and ¹³C NMR spectra and connectivities in COSY, ROESY, and HMBC spectra. The exact stereostructure of 13 was confirmed by its X-ray crystal structure analysis. Of all the compounds in the series, compound 16 containing a 5-fluoro-substituted uracil ring showed the most significant antitumor activities against murine leukemia L1210/0 (IC50 = 1.4 μg/mL), murine mammary carcinoma FM3A/0 (IC50 = 0.78 μg/mL), and, to a lesser extent, human T-lymphocyte cells Molt4/C8 (IC50 = 31.8 μg/mL) and CEM/0 cell lines (IC50 = 20.9 μg/mL).

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