773 research outputs found
Topologically massive gravity as a Pais-Uhlenbeck oscillator
We give a detailed account of the free field spectrum and the Newtonian limit
of the linearized "massive" (Pauli-Fierz), "topologically massive"
(Einstein-Hilbert-Chern-Simons) gravity in 2+1 dimensions about a Minkowski
spacetime. For a certain ratio of the parameters, the linearized free theory is
Jordan-diagonalizable and reduces to a degenerate "Pais-Uhlenbeck" oscillator
which, despite being a higher derivative theory, is ghost-free.Comment: 9 pages, no figures, RevTEX4; version 2: a new paragraph and a
reference added to the Introduction, a new appendix added to review
Pais-Uhlenbeck oscillators; accepted for publication in Class. Quant. Gra
Critical Points of D-Dimensional Extended Gravities
We study the parameter space of D-dimensional cosmological Einstein gravity
together with quadratic curvature terms. In D>4 there are in general two
distinct (anti)-de Sitter vacua. We show that for appropriate choice of the
parameters there exists a critical point for one of the vacua, for which there
are only massless tensor, but neither massive tensor nor scalar, gravitons. At
criticality, the linearized excitations have vanishing energy (as do black hole
solutions). A further restriction of the parameters gives a one-parameter
cosmological Einstein plus Weyl^2 model with a unique vacuum, whose \Lambda is
determined.Comment: 6 pages, typos correcte
Relationship among expression of basic-fibroblast growth factor, MTDH/Astrocyte elevated gene-1, adenomatous polyposis coli, matrix metalloproteinase 9,and COX-2 markers with prognostic factors in prostate carcinomas
Background: The etiopathogenesis of prostate cancer (PC) is still not clear, but hormonal, genetic, and environmental factors are thought to play a role in the tumor pathogenesis. Astrocyte elevated gene-1(AEG-1) as a novel transmembrane protein is predominantly located in the perinuclear region and endoplasmic reticulum. It has been found that AEG-1 upregulation increases the invasive ability of glioma and prostate cancer. Basic fibroblast growth factor (bFGF), matrix metalloproteinase-9 (MMP-9), cyclooxygenases-2 (COX-2), and adenomatous polyposis coli (APC) are very important in tumor progression as well. Materials and Methods: This study included 97 radical prostatectomy specimens. IHC stains for bFGF, MMP-9, COX-2, APC, and AEG-1 were performed on the tissue microarray using standard procedures. For each patient, the age, Gleason score, tumor volume, lymphovascular invasion, lymph node metastasis, surgical margin, and the invasion of vesiculoseminalis areas were assessed. Analyses were performed using the statistical PASW (ver. 18). Results: Statistically significant positive relationships were found MMP-9 and COX-2 (r = 0.242 and P = 0.017), between MMP-9 and APC (r = 0.207 and P = 0.043), and between bFGF and AEG-1 (r = 0.295 and P = 0.004). However, the relationships between age and staining results and tumor volume and staining results were not found to be significant. Although a positive correlation was found between the Gleason score and tumor volume and the Gleason score and age (r = 0.415 and P = 0.0001; r = 0.246 and P = 0.015, respectively), we did not find a statistically significant relationship between other stains and other prognostic parameters (lymphovascular invasion, lymph node metastasis, surgical margin, or vesiculoseminalis invasion). Conclusion:The relationships we found between MMP-9 and COX-2, between MMP-9, and APC and between bFGF and AEG-1 as independent prognostic parameters could be helpful in the development of new therapeutic procedures.Keywords: Adenomatous polyposis coli, astrocyte elevated gene‑1, basic fibroblast growth factor, cyclooxygenases‑2, matrix metalloproteinase‑9, prognostic parameters, prostate adenocarcinomasNigerian Journal of Clinical Practice • Oct-Dec 2013 • Vol 16 • Issue
Contextual learning for unit commitment with renewable energy sources
In this paper, we study a unit commitment (UC) problem minimizing operating costs of the power system with renewable energy sources. We develop a contextual learning algorithm for UC (CLUC) which learns which UC schedule to choose based on the context information such as past load demand and weather condition. CLUC does not require any prior knowledge on the uncertainties such as the load demand and the renewable power outputs, and learns them over time using the context information. We characterize the performance of CLUC analytically, and prove its optimality in terms of the long-term average cost. Through the simulation results, we show the performance of CLUC and the effectiveness of utilizing the context information in the UC problem. © 2016 IEEE
The chicken or the egg; or Who ordered the chiral phase transition?
We draw an analogy between the deconfining transition in the 2+1 dimensional
Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD.
Based on the detailed analysis of the former (hep-th/0010201) we suggest that
the chiral symmetry restoration in QCD at high temperature is driven by the
thermal ensemble of baryons and anti-baryons. The chiral symmetry is restored
when roughly half of the volume is occupied by the baryons. Surprisingly
enough, even though baryons are rather heavy, a crude estimate for the critical
temperature gives Mev. In this scenario the binding of the instantons
is not the cause but rather a consequence of the chiral symmetry restoration.Comment: 22 pages, 7 figures, comments about chiral symmetry at finite nuclear
density are adde
Effective Lagrangian from Higher Curvature Terms: Absence of vDVZ Discontinuity in AdS Space
We argue that the van Dam-Veltman-Zakharov discontinuity arising in the limit of the massive graviton through an explicit Pauli-Fierz mass term
could be absent in anti de Sitter space. This is possible if the graviton can
acquire mass spontaneously from the higher curvature terms or/and the massless
limit is attained faster than the cosmological constant . We discuss the effects of higher-curvature couplings and of an explicit
cosmological term () on stability of such continuity and of massive
excitations.Comment: 23 pages, Latex, the version to appear in Class. Quant. Gra
Magnetic Symmetries and Vortices In Chern-Simons Theories
We study the locality properties of the vortex operators in compact U(1)
Maxwell-Chern-Simons and SU(N) Yang-Mills-Chern-Simons theories in 2+1
dimensions. We find that these theories do admit local vortex operators and
thus in the UV regularized versions should contain stable magnetic vortices. In
the continuum limit however the energy of these vortex excitations generically
is logarithmically UV divergent. Nevertheless the classical analysis shows that
at small values of CS coefficient the vortices become light. It is
conceivable that they in fact become massless and condense due to quantum
effects below some small . If this happens the magnetic symmetry breaks
spontaneously and the theory is confining.Comment: 21 pages, laTe
The gradient flow running coupling with twisted boundary conditions
We study the gradient flow for Yang-Mills theories with twisted boundary
conditions. The perturbative behavior of the energy density is used to define a running coupling at a scale given by the
linear size of the finite volume box. We compute the non-perturbative running
of the pure gauge coupling constant and conclude that the technique is
well suited for further applications due to the relatively mild cutoff effects
of the step scaling function and the high numerical precision that can be
achieved in lattice simulations. We also comment on the inclusion of matter
fields.Comment: 27 pages. LaTe
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