211 research outputs found
QCD resummation for semi-inclusive hadron production processes
We investigate the resummation of large logarithmic perturbative corrections
to hadron production in electron-positron annihilation and semi-inclusive
deep-inelastic scattering. We find modest, but significant, enhancements of
hadron multiplicities in the kinematic regimes accessible in present
high-precision experiments. Our results are therefore relevant for the
determination of hadron fragmentation functions from data for these processes.Comment: 14 pages, 11 figure
Fragmentation Functions Beyond Fixed Order Accuracy
We give a detailed account of the phenomenology of all-order resummations of
logarithmically enhanced contributions at small momentum fraction of the
observed hadron in semi-inclusive electron-positron annihilation and the
time-like scale evolution of parton-to-hadron fragmentation functions. The
formalism to perform resummations in Mellin moment space is briefly reviewed,
and all relevant expressions up to next-to-next-to-leading logarithmic order
are derived, including their explicit dependence on the factorization and
renormalization scales. We discuss the details pertinent to a proper numerical
implementation of the resummed results comprising an iterative solution to the
time-like evolution equations, the matching to known fixed-order expressions,
and the choice of the contour in the Mellin inverse transformation. First
extractions of parton-to-pion fragmentation functions from semi-inclusive
annihilation data are performed at different logarithmic orders of the
resummations in order to estimate their phenomenological relevance. To this
end, we compare our results to corresponding fits up to fixed,
next-to-next-to-leading order accuracy and study the residual dependence on the
factorization scale in each case.Comment: 19 pages, 7 figure
Using hadron-in-jet data in a global analysis of fragmentation functions
We present a novel global QCD analysis of charged -meson fragmentation
functions at next-to-leading order accuracy. This is achieved by making use of
the available data for single-inclusive -meson production in
electron-positron annihilation, hadron-hadron collisions, and, for the first
time, in-jet fragmentation in proton-proton scattering. It is shown how to
include all relevant processes efficiently and without approximations within
the Mellin moment technique, specifically for the in-jet fragmentation cross
section. The presented technical framework is generic and can be
straightforwardly applied to future analyses of fragmentation functions for
other hadron species, as soon as more in-jet fragmentation data become
available. We choose to work within the Zero Mass Variable Flavor Number Scheme
which is applicable for sufficiently high energies and transverse momenta. The
obtained optimum set of parton-to- fragmentation functions is
accompanied by Hessian uncertainty sets which allow one to propagate
hadronization uncertainties to other processes of interest.Comment: 16 pages, 8 figure
Threshold resummation for polarized (semi-)inclusive deep inelastic scattering
We explore the effects of the resummation of large logarithmic perturbative
corrections to double-longitudinal spin asymmetries for inclusive and
semi-inclusive deep inelastic scattering in fixed-target experiments. We find
that the asymmetries are overall rather robust with respect to the inclusion of
the resummed higher-order terms. Significant effects are observed at fairly
high values of x, where resummation tends to decrease the spin asymmetries.
This effect turns out to be more pronounced for semi-inclusive scattering. We
also investigate the potential impact of resummation on the extraction of
polarized valence quark distributions in dedicated high-x experiments.Comment: 8 pages, 6 figure
Fibroblast surface-associated FGF-2 promotes contact-dependent colorectal cancer cell migration and invasion through FGFR-SRC signaling and integrin αvβ5-mediated adhesion.
Carcinoma-associated fibroblasts were reported to promote colorectal cancer (CRC) invasion by secreting motility factors and extracellular matrix processing enzymes. Less is known whether fibroblasts may induce CRC cancer cell motility by contact-dependent mechanisms. To address this question we characterized the interaction between fibroblasts and SW620 and HT29 colorectal cancer cells in 2D and 3D co-culture models in vitro. Here we show that fibroblasts induce contact-dependent cancer cell elongation, motility and invasiveness independently of deposited matrix or secreted factors. These effects depend on fibroblast cell surface-associated fibroblast growth factor (FGF) -2. Inhibition of FGF-2 or FGF receptors (FGFRs) signaling abolishes these effects. FGFRs activate SRC in cancer cells and inhibition or silencing of SRC in cancer cells, but not in fibroblasts, prevents fibroblasts-mediated effects. Using an RGD-based integrin antagonist and function-blocking antibodies we demonstrate that cancer cell adhesion to fibroblasts requires integrin αvβ5. Taken together, these results demonstrate that fibroblasts induce cell-contact-dependent colorectal cancer cell migration and invasion under 2D and 3D conditions in vitro through fibroblast cell surface-associated FGF-2, FGF receptor-mediated SRC activation and αvβ5 integrin-dependent cancer cell adhesion to fibroblasts. The FGF-2-FGFRs-SRC-αvβ5 integrin loop might be explored as candidate therapeutic target to block colorectal cancer invasion
FOXQ1 (forkhead box Q1)
Review on FOXQ1, with data on DNA/RNA, on the protein encoded and where the gene is implicated
Study of the discharge gas trapping during thin film growth
Discharge gas trapping in thin films produced by sputtering is known to be due to high energy neutrals bouncing back from the cathode. Qualitatively, the phenomenon is enhanced by raising the discharge voltage and is strongly dependent on the atomic masses of the discharge gas and of the cathode material. In addition to these known effects it is shown that, for a given gas, the trapped amount decreases with increasing the melting temperature of the deposited material. The results obtained both by sample melting and laser ablation are presented and discussed
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