24 research outputs found
From RHIC to EIC: Nuclear Structure Functions
We study the nuclear structure function and its logarithmic
derivative in the high energy limit (small region) using the Color Glass
Condensate formalism. In this limit the structure function depends on the
quark anti-quark dipole-target scattering cross section . The same dipole cross section appears in single hadron and hadron-photon
production cross sections in the forward rapidity region in deuteron
(proton)-nucleus collisions at high energy, i.e. at RHIC and LHC. We use a
parameterization of the dipole cross section, which has successfully been used
to describe the deuteron-gold data at RHIC, to compute the nuclear structure
function and its log derivative (which is related to gluon
distribution function in the double log limit). We provide a quantitative
estimate of the nuclear shadowing of and the gluon distribution
function in the kinematic region relevant to a future Electron-Ion Collider.Comment: 13 pages, 6 figure
Chromoelectric fields and quarkonium-hadron interactions at high energies
We develop a simple model to study the heavy quarkonium-hadron cross section
in the high energy limit. The hadron is represented by an external electric
color field (capacitor) and the heavy quarkonium is represented by a small
color dipole. Using high energy approximations we compute the relevant cross
sections, which are then compared with results obtained with other methods. Our
calculations are presented in a pedagogical way accessible to undergraduate
students.Comment: To appear in Physical Review C, 24 pages, 10 eps figure
Exclusive vector meson production in electron-ion collisions
We calculate the nuclear cross section for coherent and incoherent vector
meson production within the QCD color dipole picture, including saturation
effects. Theoretical estimates for scattering on both light and heavy nuclei
are given over a wide range of energy.Comment: 11 pages, 6 figures, 1 tabl
Nuclear shadowing in Glauber-Gribov theory with Q2-evolution
We consider deep inelastic scattering off nuclei in the Regge limit within
the Glauber-Gribov model. Using unitarized parton distribution functions for
the proton, we find sizeable shadowing effects on the nuclear total and
longitudinal structure functions, and , in the low-x limit.
Extending a fan-diagram analysis for the large-mass region of coherent
diffraction off nuclei to high Q2, we also find significant shadowing effects
in this kinematical regime. Finally, we discuss shortcomings of our approach
and possible extensions of the model to other kinematical regimes.Comment: 16 pages, 9 figure
Spatial regulation of the glycocalyx component podocalyxin is a switch for prometastatic function
The glycocalyx component and sialomucin podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumor types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high and low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis
Non-linear QCD dynamics in two-photon interactions at high energies
Perturbative QCD predicts that the growth of the gluon density at high
energies should saturate, forming a Color Glass Condensate (CGC), which is
described in mean field approximation by the Balitsky-Kovchegov (BK) equation.
In this paper we study the interactions at high energies and
estimate the main observables which will be probed at future linear colliders
using the color dipole picture. We discuss in detail the dipole - dipole cross
section and propose a new relation between this quantity and the dipole
scattering amplitude. The total ,
cross-sections and the real photon structure function are
calculated using the recent solution of the BK equation with running coupling
constant and the predictions are compared with those obtained using
phenomenological models for the dipole-dipole cross section and scattering
amplitude. We demonstrate that these models are able to describe the LEP data
at high energies, but predict a very different behavior for the observables at
higher energies. Therefore we conclude that the study of
interactions can be useful to constrain the QCD dynamics.Comment: 11 pages, 5 figures. Version to be published in European Physical
Journal
pTcGW plasmid vectors 1.1 version: a versatile tool for Trypanosoma cruzi gene characterisation
Ortholog of the polymerase theta helicase domain modulates DNA replication in Trypanosoma cruzi
DNA polymerase theta (Polθ), a member of the DNA polymerase family A, exhibits a polymerase C-terminal domain, a central domain, and an N-terminal helicase domain. Polθ plays important roles in DNA repair via its polymerase domain, regulating genome integrity. In addition, in mammals, Polθ modulates origin firing timing and MCM helicase recruitment to chromatin. In contrast, as a model eukaryote, Trypanosoma cruzi exhibits two individual putative orthologs of Polθ in different genomic loci; one ortholog is homologous to the Polθ C-terminal polymerase domain, and the other is homologous to the Polθ helicase domain, called Polθ-polymerase and Polθ-helicase, respectively. A pull-down assay using the T. cruzi component of the prereplication complex Orc1/Cdc6 as bait captured Polθ-helicase from the nuclear extract. Orc1/Cdc6 and Polθ-helicase directly interacted, and Polθ-helicase presented DNA unwinding and ATPase activities. A T. cruzi strain overexpressing the Polθ-helicase domain exhibited a significantly decreased amount of DNA-bound MCM7 and impaired replication origin firing. Taken together, these data suggest that Polθ-helicase modulates DNA replication by directly interacting with Orc1/Cdc6, which reduces the binding of MCM7 to DNA and thereby impairs the firing of replication origins