Measurement of the relative fraction of t$\bar{t}$ events produced via gluon fusion in p$\bar{p}$ collision at √s = 1.96 TeV at CDF

Abstract

In this thesis we present a measurement of the relative fraction of tt events produced via gluon-fusion to the total number of tt events. Using the kinematics of the production and decay of the top and antitop quark pair, we trained a Neural Network to discriminate the gluon-fusion events. The Neural Network was then used as a template to fit for the gluon-fusion fraction in data. Using a total integrated luminosity of 955 pb −1 we find σ(gg→tt) σ(pp→tt) < 0.33 at 68% confidence level and σ(gg→tt) σ(pp→tt) < 0.61 at 95% confidence level.ii

Mapping Post-Translational Modifications of de Novo Purine Biosynthetic Enzymes: Implications for Pathway Regulation

“…The first enzyme in the pathway is amidophosphoribosyltransferase (PPAT), is subjected to feedback inhibition by nucleotides, and has been hypothesized to be rate-limiting. [3][4][5][6] PPAT is activated by the proteolytic cleavage of the first 11 residues, and its activity decreased upon the oxidation of a bound [4Fe-4S] cluster. 7 ' 8 Recently, PPAT and formylglycinamidine ribonuleotide synthase (PFAS) were shown to be under the regulation of heat shock protein 90 (HSP90), whereby inhibition of HSP90 with ganetespib resulted in a marked decrease in their interaction with HSP90 and enhanced proteolytic degradation.…”