596 research outputs found
The large-N(c) nuclear potential puzzle
An analysis of the baryon-baryon potential from the point of view of
large-N(c) QCD is performed. A comparison is made between the N(c)-scaling
behavior directly obtained from an analysis at the quark-gluon level to the
N(c)-scaling of the potential for a generic hadronic field theory in which it
arises via meson exchanges and for which the parameters of the theory are given
by their canonical large-N(c) scaling behavior. The purpose of this comparison
is to use large-N(c) consistency to test the widespread view that the
interaction between nuclei arises from QCD through the exchange of mesons.
Although at the one- and two-meson exchange level the scaling rules for the
potential derived from the hadronic theory matches the quark-gluon level
prediction, at the three- and higher-meson exchange level a generic hadronic
theory yields a potential which scales with N(c) faster than that of the
quark-gluon theory.Comment: 17 pages, LaTeX, 5 figure
Development of locally representative seismic hazard models
Seismic hazard studies in regions of low and moderate seismic activities often resort to the use of attenuation relationships developed elsewhere but there are always doubts as to whether these imported relationships are representative of local conditions. Numerous well established stochastic attenuation models have also been developed for applications in Central and Eastern North America. However, such intraplate models could not be generalised across the globe to other regions of low and moderate seismic activities. Modelling the spatial and temporal distribution of seismic activities can also be thwarted with difficulties because of the paucity of data. This paper presents the experiences of the authors in overcoming these challenges when undertaking seismic hazard studies in different countries. Topics covered in the paper include attenuation modelling and the evaluation of seismic hazards for the determination of the earthquake loading model for engineering design
Galois theory and Lubin-Tate cochains on classifying spaces
We consider brave new cochain extensions F(BG +,R) → F(EG +,R), where R is either a Lubin-Tate spectrum E n or the related 2-periodic Morava K-theory K n , and G is a finite group. When R is an Eilenberg-Mac Lane spectrum, in some good cases such an extension is a G-Galois extension in the sense of John Rognes, but not always faithful. We prove that for E n and K n these extensions are always faithful in the K n local category. However, for a cyclic p-group C p r, the cochain extension F(BC p r +,E n ) → F(EC p r +, E n ) is not a Galois extension because it ramifies. As a consequence, it follows that the E n -theory Eilenberg-Moore spectral sequence for G and BG does not always converge to its expected target
Irreducible Characters of General Linear Superalgebra and Super Duality
We develop a new method to solve the irreducible character problem for a wide
class of modules over the general linear superalgebra, including all the
finite-dimensional modules, by directly relating the problem to the classical
Kazhdan-Lusztig theory. We further verify a parabolic version of a conjecture
of Brundan on the irreducible characters in the BGG category \mc{O} of the
general linear superalgebra. We also prove the super duality conjecture
Expansion for Excited Baryons
We derive consistency conditions which constrain the possible form of the
strong couplings of the excited baryons to the pions. The consistency
conditions follow from requiring the pion-excited baryon scattering amplitudes
to satisfy the large-N_c Witten counting rules and are analogous to consistency
conditions used by Dashen, Jenkins and Manohar and others for s-wave baryons.
The consistency conditions are explicitly solved, giving the most general
allowed form of the strong vertices for excited baryons in the large-N_c limit.
We show that the solutions to the large-N_c consistency conditions coincide
with the predictions of the nonrelativistic quark model for these states,
extending the results previously obtained for the s-wave baryons. The 1/N_c
corrections to these predictions are studied in the quark model with arbitrary
number of colors N_c.Comment: 56 pages, REVTeX; one new Appendix added containing a discussion of
the results in the language of quark operator
Super duality and irreducible characters of ortho-symplectic Lie superalgebras
We formulate and establish a super duality which connects parabolic
categories between the ortho-symplectic Lie superalgebras and classical Lie
algebras of types. This provides a complete and conceptual solution of
the irreducible character problem for the ortho-symplectic Lie superalgebras in
a parabolic category , which includes all finite-dimensional irreducible
modules, in terms of classical Kazhdan-Lusztig polynomials.Comment: 30 pages, Section 5 rewritten and shortene
Mechanistic target of rapamycin (MTOR) protein expression in the tumor and its microenvironment correlates with more aggressive pathology at cystectomy
Background: The mechanistic target of rapamycin (mTOR) has been implicated in driving tumor biology in multiple malignancies, including urothelial carcinoma (UC). We investigate how mTOR and phosphorylated mTOR (pmTOR) protein expression correlate with chemoresponsiveness in the tumor and its microenvironment at final pathologic staging after neoadjuvant chemotherapy (NAC). Methods: A single-institution retrospective analysis was performed on 62 patients with cT2–4Nany UC undergoing NAC followed by radical cystectomy. Diagnostic (transurethral resection specimens, TURBT) and postchemotherapy radical cystectomy specimens were evaluated for mTOR and pmTOR protein expression using immunohistochemistry of the tumor, peritumoral stroma, and normal surrounding stroma. Protein expression levels were compared between clinical and pathologic stage. Whole transcriptome analysis was performed to evaluate mRNA expression relative to mTOR pathway activation. Results: Baseline levels of mTOR and pmTOR within TURBT specimens were not associated with clinical stage and response to chemotherapy overall. Nonresponders with advanced pathologic stage at cystectomy (ypT2–4/ypTanyN+) had significantly elevated mTOR tumor staining (P = 0.006) and a sustained mTOR and pmTOR staining in the peritumoral and surrounding normal stroma (NS). Several genes relevant to mTOR activity were found to be up-regulated in the tumors of nonresponders. Remarkably, complete responders at cystectomy (ypT0) had significant decreases in both mTOR and pmTOR protein expression in the peritumoral and normal stroma (P = 0.01–0.03). Conclusions: Our results suggest that mTOR pathway activity is increased in tumor and sustained in its microenvironment in patients with adverse pathologic findings at cystectomy. These findings suggest the relevance of targeting this pathway in bladder cancer
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Synthesis of accelerograms compatible with the Chinese GB 50011-2001 design spectrum via harmonic wavelets: artificial and historic records
A versatile approach is employed to generate artificial accelerograms which satisfy the compatibility criteria prescribed by the Chinese aseismic code provisions GB 50011-2001. In particular, a frequency dependent peak factor derived by means of appropriate Monte Carlo analyses is introduced to relate the GB 50011-2001 design spectrum to a parametrically defined evolutionary power spectrum (EPS). Special attention is given to the definition of the frequency content of the EPS in order to accommodate the mathematical form of the aforementioned design spectrum. Further, a one-to-one relationship is established between the parameter controlling the time-varying intensity of the EPS and the effective strong ground motion duration. Subsequently, an efficient auto-regressive moving-average (ARMA) filtering technique is utilized to generate ensembles of non-stationary artificial accelerograms whose average response spectrum is in a close agreement with the considered design spectrum. Furthermore, a harmonic wavelet based iterative scheme is adopted to modify these artificial signals so that a close matching of the signals’ response spectra with the GB 50011-2001 design spectrum is achieved on an individual basis. This is also done for field recorded accelerograms pertaining to the May, 2008 Wenchuan seismic event. In the process, zero-phase high-pass filtering is performed to accomplish proper baseline correction of the acquired spectrum compatible artificial and field accelerograms. Numerical results are given in a tabulated format to expedite their use in practice
Scaling violations: Connections between elastic and inelastic hadron scattering in a geometrical approach
Starting from a short range expansion of the inelastic overlap function,
capable of describing quite well the elastic pp and scattering data,
we obtain extensions to the inelastic channel, through unitarity and an impact
parameter approach. Based on geometrical arguments we infer some
characteristics of the elementary hadronic process and this allows an excellent
description of the inclusive multiplicity distributions in and
collisions. With this approach we quantitatively correlate the violations of
both geometrical and KNO scaling in an analytical way. The physical picture
from both channels is that the geometrical evolution of the hadronic
constituents is principally reponsible for the energy dependence of the
physical quantities rather than the dynamical (elementary) interaction itself.Comment: 16 pages, aps-revtex, 11 figure
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