1,106 research outputs found
Impact parameter dependence of parton densities at low x
We consider impact parameter dependence of the polarized and unpolarized
parton densities. Unitarity does not allow factorization of these structure
functions over the Bjorken x and the impact parameter b variables. On the basis
of the particular geometrical model approach we conclude that spin of
constituent quark may have a significant orbital angular momentum component
which can manifest itself through the peripherality of the spin dependent
structure functions.Comment: 4 pages, to appear in the Proceedings of the Workshop Diffraction
2000, Cetraro, Italy, 2-7 September 200
Spin correlations due to antishadowing
The effects of antishadowing related to the spin correlations of particles in
multiparticle production are discussed. It is shown that significant spin
correlations should be expected at the LHC energies.Comment: 5 pages, 1 figure, minor change
Identification of the growth arrest and DNA damage protein GADD34 in the normal human heart and demonstration of alterations in expression following myocardial ischaemia
Growth arrest and DNA damage protein 34 (GADD34) is a multifunctional protein upregulated in response to cellular stress and is believed to mediate DNA repair and restore protein synthesis. In the present study we have examined GADD34 immunoreactivity in human myocardial tissue at defined survival times following cardiac arrest and determined alterations in expression following ischaemia. In the normal human heart, GADD34 immunoreactivity was generally intense and present within most cells. GADD34 immunoreactivity was downregulated in tissue displaying ischaemic damage and remained intense in adjacent non-infarcted tissue. Unlike brain, GADD34 was not found to be upregulated in the peri-infarct zone. Cells displaying apoptotic changes were located in regions displaying reduced GADD34 immunoreactivity. In the brain, it is thought that GADD34 supports re-initiation of protein synthesis following ischaemia. Similarly, GADD34 may perform important functions in cardiac tissue in response to ischaemia
Minimum-error discrimination between symmetric mixed quantum states
We provide a solution of finding optimal measurement strategy for
distinguishing between symmetric mixed quantum states. It is assumed that the
matrix elements of at least one of the symmetric quantum states are all real
and nonnegative in the basis of the eigenstates of the symmetry operator.Comment: 10 page
Energy Spectrum of Anyons in a Magnetic Field
For the many-anyon system in external magnetic field, we derive the energy
spectrum as an exact solution of the quantum eigenvalue problem with particular
topological constraints. Our results agree with the numerical spectra recently
obtained for the 3- and the 4-anyon systems.Comment: 11 pages in Plain LaTeX (plus 4 figures available on request), DFPD
92/TH/4
Anomalous broadening of the spin-flop transition in the reentrant spin-glass phase of LaSrCuO ()
The magnetization in a lightly doped LaSrCuO ()
single crystal was measured. Spin-flop transition was clearly observed in the
hole doped antiferromagnetically ordered state under increasing magnetic fields
perpendicular to the CuO plane. In the spin-glass phase below 25K, the
spin-flop transition becomes broad but the step in the magnetization curve
associated with the transition remains finite at the lowest temperature. We
show in this report that, at low temperature, the homogeneous antiferromagnetic
order is disturbed by the re-distribution of holes, and that the spatial
variance of the local hole concentration around increases.Comment: to be published to Physical Review
Product Groups, Discrete Symmetries, and Grand Unification
We study grand unified theories based on an SU(5)xSU(5) gauge group in which
the GUT scale, M_{GUT}, is the VEV of an exact or approximate modulus, and in
which fast proton decay is avoided through a combination of a large triplet
mass and small triplet couplings. These features are achieved by discrete
symmetries. In many of our models, M_{GUT} is generated naturally by the
balance of higher dimension terms that lift the GUT modulus potential, and soft
supersymmetry breaking masses. The theories often lead to interesting patterns
of quark and lepton masses. We also discuss some distinctions between grand
unified theories and string unification.Comment: 23 pages; no figures; revtex
Clinical and molecular characterization of HER2 amplified-pancreatic cancer
<p>Background:
Pancreatic cancer is one of the most lethal and molecularly diverse malignancies. Repurposing of therapeutics that target specific molecular mechanisms in different disease types offers potential for rapid improvements in outcome. Although HER2 amplification occurs in pancreatic cancer, it is inadequately characterized to exploit the potential of anti-HER2 therapies.</p>
<p>Methods:
HER2 amplification was detected and further analyzed using multiple genomic sequencing approaches. Standardized reference laboratory assays defined HER2 amplification in a large cohort of patients (n = 469) with pancreatic ductal adenocarcinoma (PDAC).</p>
<p>Results:
An amplified inversion event (1 MB) was identified at the HER2 locus in a patient with PDAC. Using standardized laboratory assays, we established diagnostic criteria for HER2 amplification in PDAC, and observed a prevalence of 2%. Clinically, HER2- amplified PDAC was characterized by a lack of liver metastases, and a preponderance of lung and brain metastases. Excluding breast and gastric cancer, the incidence of HER2-amplified cancers in the USA is >22,000 per annum.</p>
<p>Conclusions:
HER2 amplification occurs in 2% of PDAC, and has distinct features with implications for clinical practice. The molecular heterogeneity of PDAC implies that even an incidence of 2% represents an attractive target for anti-HER2 therapies, as options for PDAC are limited. Recruiting patients based on HER2 amplification, rather than organ of origin, could make trials of anti-HER2 therapies feasible in less common cancer types.</p>
Non-Fermi liquid regime of a doped Mott insulator
We study the doping of a Mott insulator in the presence of quenched
frustrating disorder in the magnetic exchange. A low doping regime
is found, in which the quasiparticle coherent scale is low : with (the ratio of typical exchange to
hopping). In the ``quantum critical regime'' , several
physical quantities display Marginal Fermi Liquid behaviour : NMR relaxation
time , resistivity , optical lifetime
\tau_{opt}^{-1}\propto \omega/\ln(\omega/\epstar) and response functions obey
scaling, e.g. .
In contrast, single-electron properties display stronger deviations from Fermi
liquid theory in this regime with a dependence of the inverse
single-particle lifetime and a decay of the photoemission
intensity. On the basis of this model and of various experimental evidence, it
is argued that the proximity of a quantum critical point separating a glassy
Mott-Anderson insulator from a metallic ground-state is an important ingredient
in the physics of the normal state of cuprate superconductors (particularly the
Zn-doped materials). In this picture the corresponding quantum critical regime
is a ``slushy'' state of spins and holes with slow spin and charge dynamics
responsible for the anomalous properties of the normal state.Comment: 40 pages, RevTeX, including 13 figures in EPS. v2 : minor changes,
some references adde
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