352 research outputs found
Peculiar scaling of self-avoiding walk contacts
The nearest neighbor contacts between the two halves of an N-site lattice
self-avoiding walk offer an unusual example of scaling random geometry: for N
going to infinity they are strictly finite in number but their radius of
gyration Rc is power law distributed, ~ Rc^{-\tau}, where \tau>1 is a novel
exponent characterizing universal behavior. A continuum of diverging lengths
scales is associated to the Rc distribution. A possibly super-universal \tau=2
is also expected for the contacts of a self-avoiding or random walk with a
confining wall.Comment: 4 pages, 5 Postscript figures, uses psfig.sty; some sentences
clarifie
Science Requirements and Conceptual Design for a Polarized Medium Energy Electron-Ion Collider at Jefferson Lab
This report presents a brief summary of the science opportunities and program
of a polarized medium energy electron-ion collider at Jefferson Lab and a
comprehensive description of the conceptual design of such a collider based on
the CEBAF electron accelerator facility.Comment: 160 pages, ~93 figures This work was supported by the U.S. Department
of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177,
DE-AC02-06CH11357, DE-AC05-060R23177, and DESC0005823. The U.S. Government
retains a non-exclusive, paid-up, irrevocable, world-wide license to publish
or reproduce this manuscript for U.S. Government purpose
Critical Exponents, Hyperscaling and Universal Amplitude Ratios for Two- and Three-Dimensional Self-Avoiding Walks
We make a high-precision Monte Carlo study of two- and three-dimensional
self-avoiding walks (SAWs) of length up to 80000 steps, using the pivot
algorithm and the Karp-Luby algorithm. We study the critical exponents
and as well as several universal amplitude ratios; in
particular, we make an extremely sensitive test of the hyperscaling relation
. In two dimensions, we confirm the predicted
exponent and the hyperscaling relation; we estimate the universal
ratios , and (68\% confidence
limits). In three dimensions, we estimate with a
correction-to-scaling exponent (subjective 68\%
confidence limits). This value for agrees excellently with the
field-theoretic renormalization-group prediction, but there is some discrepancy
for . Earlier Monte Carlo estimates of , which were , are now seen to be biased by corrections to scaling. We estimate the
universal ratios and ; since , hyperscaling holds. The approach to
is from above, contrary to the prediction of the two-parameter
renormalization-group theory. We critically reexamine this theory, and explain
where the error lies.Comment: 87 pages including 12 figures, 1029558 bytes Postscript
(NYU-TH-94/09/01
MEIC Design Progress
This paper will report the recent progress in the conceptual design of MEIC, a high luminosity medium energy polarized ring-ring electron-ion collider at Jefferson lab. The topics and achievements that will be covered are design of the ion large booster and the ERL-circulator-ring-based electron cooling facility, optimization of chromatic corrections and dynamic aperture studies, schemes and tracking simulations of lepton and ion polarization in the figure-8 collider ring, and the beam-beam and electron cooling simulations. A proposal of a test facility for the MEIC electron cooler will also be discussed
The human epidermal growth factor receptor (EGFR) gene in European patients with advanced colorectal cancer harbors infrequent mutations in its tyrosine kinase domain
ABSTRACT: BACKGROUND: The epidermal growth factor receptor (EGFR), a member of the ErbB family of receptors, is a transmembrane tyrosine kinase (TK) activated by the binding of extracellular ligands of the EGF-family and involved in triggering the MAPK signaling pathway, which leads to cell proliferation. Mutations in the EGFR tyrosine kinase domain are frequent in non-small-cell lung cancer (NSCLC). However, to date, only very few, mainly non-European, studies have reported rare EGFR mutations in colorectal cancer (CRC). METHODS: We screened 236 clinical tumor samples from European patients with advanced CRC by direct DNA sequencing to detect potential, as yet unknown mutations, in the EGFR gene exons 18 to 21, mainly covering the EGFR TK catalytic domain. RESULTS: EGFR sequences showed somatic missense mutations in exons 18 and 20 at a frequency of 2.1% and 0.4% respectively. Somatic SNPs were also found in exons 20 and 21 at a frequency of about 3.1% and 0.4% respectively. Of these mutations, four have not yet been described elsewhere. CONCLUSIONS: These mutation frequencies are higher than in a similarly sized population characterized by Barber and colleagues, but still too low to account for a major role played by the EGFR gene in CRC.Peer reviewe
Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review
Peer reviewedPublisher PD
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