1,518 research outputs found
New Scaling Law for Deuteron Production in Ultra-Relativistic Nucleus Nucleus Collisions
Deuteron production in S and Pb induced collisions at beam energies of 200
and 160 AGeV is studied in the framework of the transport theoretical approach
RQMD. Strong transverse flow invalidates the differential coalescence formula
in momentum space. The transverse momentum integrated yields scale in a
broad rapidity interval with the squared proton densities and inversely with
the produced particle rapidity densities. This kind of scaling can be linked to
constant relative sizes of nucleon and pion sources at freeze-out. With
increasing projectile mass the nucleon source blows up stronger than the pion
source. As a result, the scaled deuteron densities drop in central Pb+Pb
collisions by 15 percent as compared to S induced reactions.Comment: 12 pages + 4 postscript figures (uuencoded and included
Highly sensitive optical hydrogen sensor using circular Pd-coated singlemode tapered fibre
A novel optical hydrogen sensor, based on the absorption change of the evanescent fields in a circular Pd-coated singlemode tapered fibre is presented. The proposed sensor is polarisation independent and its sensitivity is adjustable by means of the taper diameter, interaction length, and/or light wavelength. A simple light transmission measurement setup is used to test the sensor. The sensor is suitable for the detection of low hydrogen concentrations with high sensitivity and fast time response. Transmission changes as high as 60% are demonstrated
Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation
We examine the time-reversal-violating nuclear ``Schiff moment'' that induces
electric dipole moments in atoms. After presenting a self-contained derivation
of the form of the Schiff operator, we show that the distribution of Schiff
strength, an important ingredient in the ground-state Schiff moment, is very
different from the electric-dipole-strength distribution, with the Schiff
moment receiving no strength from the giant dipole resonance in the
Goldhaber-Teller model. We then present shell-model calculations in light
nuclei that confirm the negligible role of the dipole resonance and show the
Schiff strength to be strongly correlated with low-lying octupole strength.
Next, we turn to heavy nuclei, examining recent arguments for the strong
enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg,
for example. We concur that there is a significant enhancement while pointing
to effects neglected in previous work (both in the octupole-deformed nuclides
and 199Hg) that may reduce it somewhat, and emphasizing the need for
microscopic calculations to resolve the issue. Finally, we show that static
octupole deformation is not essential for the development of collective Schiff
moments; nuclei with strong octupole vibrations have them as well, and some
could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex
Universal deformation rings for the symmetric group S_4
Let k be an algebraically closed field of characteristic 2, and let W be the
ring of infinite Witt vectors over k. Let S_4 denote the symmetric group on 4
letters. We determine the universal deformation ring R(S_4,V) for every
kS_4-module V which has stable endomorphism ring k and show that R(S_4,V) is
isomorphic to either k, or W[t]/(t^2,2t), or the group ring W[Z/2]. This gives
a positive answer in this case to a question raised by the first author and
Chinburg whether the universal deformation ring of a representation of a finite
group with stable endomorphism ring k is always isomorphic to a subquotient
ring of the group ring over W of a defect group of the modular block associated
to the representation.Comment: 12 pages, 2 figure
Phenomenological Aspects of Isospin Violation in the Nuclear Force
Phenomenological Lagrangians and dimensional power counting are used to
assess isospin violation in the nucleon-nucleon force. The coupling
constants (including the Goldberger-Treiman discrepancy), charge-symmetry
breaking, and meson-mixing models are examined. A one-loop analysis of the
isospin-violating coupling constants is performed using chiral
perturbation theory. Meson-mixing models and the He - H mass difference
are also discussed in the context of naturalness.Comment: 10 pages, latex, 1 figure -- To appear in Physics Letters B --
epsfig.sty require
Note on Tests of the Factorization Hypothesis and the Determination of Meson Decay Constants
We discuss various tests of the factorization hypothesis making use of the
close relationship between semi-leptonic and factorized nonleptonic decay
amplitudes. It is pointed out that factorization leads to truely
model-independent predictions for the ratio of nonleptonic to semi-leptonic
decay rates, if in the nonleptonic decay a spin one meson of arbitrary mass or
a pion take the place of the lepton pair. Where the decay constants of those
mesons are known, these predictions represent ideal tests of the factorization
hypothesis. In other cases they may be used to extract the decay constants.
Currently available data on the decays are shown to be in excellent agreement with
the factorization results. A weighted average of the four independent values
for the QCD coefficient extracted from the data gives
suggesting that it may be equal to the Wilson coefficient evaluated
at the scale .Comment: (9 pages, ReVTeX, no figures), HD-THEP-92-3
Aspects of Nucleon Compton Scattering
We consider the spin-averaged nucleon forward Compton scattering amplitude in
heavy baryon chiral perturbation theory including all terms to order . The chiral prediction for the spin-averaged forward Compton scattering
amplitude is in good agreement with the data for photon energies MeV. We also evaluate the nucleon electric and magnetic Compton
polarizabilities to this order and discuss the uncertainties of the various
counter terms entering the chiral expansion of these quantities.Comment: 17 pp, TeX, 7 figures available from the authors, preprint CRN-93/5
Optical Spectra of SNR Candidates in NGC 300
We present moderate-resolution (<5A) long-slit optical spectra of 51 nebular
objects in the nearby Sculptor Group galaxy NGC 300 obtained with the 2.3 meter
Advanced Technology Telescope at Siding Spring Observatory, Australia. Adopting
the criterion of [SII]/Ha>=0.4 to confirm supernova remnants (SNRs) from
optical spectra, we find that of 28 objects previously proposed as SNRs from
optical observations, 22 meet this criterion with six showing [SII]/Ha of less
than 0.4. Of 27 objects suggested as SNRs from radio data, four are associated
with the 28 previously proposed SNRs. Of these four, three (included in the 22
above) meet the criterion. In all, 22 of the 51 nebular objects meet the
[SII]/Ha criterion as SNRs while the nature of the remaining 29 objects remains
undetermined by these observations.Comment: Accepted for publication in Astrophysics & Space Scienc
The role of RHAMM in cancer: Exposing novel therapeutic vulnerabilities
PUBLISHED 10 August 2022Receptor for hyaluronic acid-mediated motility (RHAMM) is a cell surface receptor for hyaluronic acid that is critical for cell migration and a cell cycle protein involved in microtubule assembly and stability. These functions of RHAMM are required for cellular stress responses and cell cycle progression but are also exploited by tumor cells for malignant progression and metastasis. RHAMM is often overexpressed in tumors and is an independent adverse prognostic factor for a number of cancers such as breast and prostate. Interestingly, pharmacological or genetic inhibition of RHAMM in vitro and in vivo ablates tumor invasiveness and metastatic spread, implicating RHAMM as a potential therapeutic target to restrict tumor growth and improve patient survival. However, RHAMM's pro-tumor activity is dependent on its subcellular distribution, which complicates the design of RHAMM-directed therapies. An alternative approach is to identify downstream signaling pathways that mediate RHAMM-promoted tumor aggressiveness. Herein, we discuss the pro-tumoral roles of RHAMM and elucidate the corresponding regulators and signaling pathways mediating RHAMM downstream events, with a specific focus on strategies to target the RHAMM signaling network in cancer cells.Josephine A. Hinneh, Joanna L. Gillis, Nicole L. Moore, Lisa M. Butler and Margaret M. Centener
Spin Interacting Fields and Heavy Baryon Chiral Perturbation Theory
We analyze the consistency of the Chiral Lagrangian approach to the
description of the spin 3/2 interacting theory. We argue that to lowest order
in the 1/m expansion, the formalism leads to the appropriated constraints and
the theory is free of the so called ``off shell" ambiguities.Comment: 12 pages, Late
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