4,241 research outputs found
Gluon distributions in nuclei at small x: guidance from different models
Different approaches to gluon shadowing at small x are reviewed. Some
available results relevant for RHIC and LHC are compared.Comment: 6 pages, LaTeX2e, uses enclosed cernrep.cls, one eps figure enclosed
using graphicx, contribution to the Yellow Report on Hard Probes in Heavy Ion
Collisions at the LH
Medium Modification of the Jet Properties
In the case that a dense medium is created in a heavy ions collision,
high-E_t jets are expected to be broadened by medium-modified gluon emission.
This broadening is directly related, through geometry, to the energy loss
measured in inclusive high-p_t particle suppression. We present here the
modifications of jet observables due to the presence of a medium for the case
of azimuthal jet energy distributions and k_t-differential multiplicities
inside the jets.Comment: 4 pages, 3 postscript figures. Proceedings for Quark Matter 200
How sensitive are high-pt electron spectra at RHIC to heavy quark energy loss?
In nucleus-nucleus collisions, high-pt electron spectra depend on the medium
modified fragmentation of their massive quark parents, thus giving novel access
to the predicted mass hierarchy of parton energy loss. Here we calculate these
spectra in a model, which supplements the perturbative QCD factorization
formalism with parton energy loss. In general, we find - within large errors -
rough agreement between theory and data on the single inclusive electron
spectrum in pp, its nuclear modification factor, and its azimuthal anisotropy.
However, the nuclear modification factor depends on the relative contribution
of charm and bottom production, which we find to be affected by large
perturbative uncertainties. In order for electron measurements to provide a
significantly more stringent test of the expected mass hierarchy, one must then
disentangle the b- and c-decay contributions, for instance by reconstructing
the displaced decay vertices.Comment: 9 pages RevTex, 4 eps-figures, asci-file containing numerical tables
of results include
Charm quenching in heavy-ion collisions at the LHC
D-meson suppression in Pb-Pb collisions at the LHC due to charm quark
in-medium energy loss is estimated within a model that describes the available
quenching measurements at RHIC. The result is compared to that previously
published by the author. The expected sensitivity of the ALICE experiment for
studying charm energy loss via fully-reconstructed D^0-meson decays is also
presented.Comment: 8 pages, 3 figures. To appear in the proceedings of Hot Quarks 2004:
Workshop for Young Scientists on the Physics of Ultrarelativistic
Nucleus-Nucleus Collisions, Taos Valley, New Mexico, 18-24 July 2004.
Submitted to J. Phys.
Ks1, an epithelial cell-specific gene, responds to early signals of head formation in Hydra
As a molecular marker for head specification in
Hydra, we
have cloned an epithelial cell-specific gene which responds
to early signals of head formation. The gene, designated
ks1, encodes a 217-amino acid protein lacking significant
sequence similarity to any known protein. KS1 contains a
N-terminal signal sequence and is rich in charged residues
which are clustered in several domains. ks1 is expressed in
tentacle-specific epithelial cells (battery cells) as well as in
a small fraction of ectodermal epithelial cells in the gastric
region subjacent to the tentacles. Treatment with the
protein kinase C activator 12-O-tetradecanoylphorbol-13-
acetate (TPA) causes a rapid increase in the level of ks1
mRNA in head-specific epithelial cells and also induces
ectopic ks1 expression in cells of the gastric region.
Sequence elements in the 5
Âą-flanking region of ks1 that are
related to TPA-responsive elements may mediate the TPA
inducibility of ks1 expression. The pattern of expression of
ks1 suggests that a ligand-activated diacylglycerol second
messenger system is involved in head-specific differentiation
Nuclear Shadowing and Diffraction
The relation between diffraction in lepton-proton collisions and shadowing of
nuclear structure functions which arises from Gribov inelastic shadowing, is
described. A model realizing such relation, which produces a parameter-free
description of experimental data on nuclear structure functions at small ,
is presented. The application to the description of multiplicities in nuclear
collisions is discussed and related to other approaches.Comment: LaTeX, 6 pages, 5 eps figures, uses enclosed ws-ijmpa.cls; invited
talk given by N. Armesto at the Eighth Workshop on Non-Perturbative Quantum
Chromodynamics, Paris, France, June 7th-11th 200
Nuclear size and rapidity dependence of the saturation scale from QCD evolution and experimental data
The solutions of the Balitsky-Kovchegov evolution equations are studied
numerically and compared with known analytical estimations. The rapidity and
nuclear size dependences of the saturation scale are obtained for the cases of
fixed and running coupling constant. These same dependences are studied in
experimental data, on lepton-nucleus, deuteron-nucleus and nucleus-nucleus
collisions, through geometric scaling and compared with the theoretical
calculations.Comment: 8 pages, 8 figures. Contribution based on talks given by J. G.
Milhano and C. A. Salgado to the proceedings of ``Hard Probes 2004'',
Ericeira (Portugal), November 4-10, 200
Hydra tropomyosin TROP1 is expressed in head-specific epithelial cells and is a major component of the cytoskeletal structure that anchors nematocytes
A cDNA clone encoding a 253 amino acid tropomyosin was
isolated from
Hydra in a differential screen for headspecific
genes. The Hydra tropomyosin gene, designated
trop1, is a single copy gene, lacks introns and is strongly
expressed in tentacle-specific epithelial cells. Analysis of
protein synthesis in head and gastric tissue indicated a high
rate of tropomyosin synthesis in head tissue. Immunolocalization
of tropomyosin in tentacle tissue revealed a
cushion-like tropomyosin-containing structure within
battery cells at the base of nematocytes. The structure
appears to form part of the cytoskeletal anchor for nematocytes.
Tropomyosin cushions were also observed in
epithelial cells along the body column, which contain
mounted stenotele nematocytes
Nuclear collisions at the Future Circular Collider
The Future Circular Collider is a new proposed collider at CERN with
centre-of-mass energies around 100 TeV in the pp mode. Ongoing studies aim at
assessing its physics potential and technical feasibility. Here we focus on
updates in physics opportunities accessible in pA and AA collisions not covered
in previous Quark Matter contributions, including Quark-Gluon Plasma and gluon
saturation studies, novel hard probes of QCD matter, and photon-induced
collisions.Comment: 4 pages, 5 figures, proceedings of Quark Matter 201
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