1,153 research outputs found
Brezin-Gross-Witten model as "pure gauge" limit of Selberg integrals
The AGT relation identifies the Nekrasov functions for various N=2 SUSY gauge
theories with the 2d conformal blocks, which possess explicit Dotsenko-Fateev
matrix model (beta-ensemble) representations the latter being polylinear
combinations of Selberg integrals. The "pure gauge" limit of these matrix
models is, however, a non-trivial multiscaling large-N limit, which requires a
separate investigation. We show that in this pure gauge limit the Selberg
integrals turn into averages in a Brezin-Gross-Witten (BGW) model. Thus, the
Nekrasov function for pure SU(2) theory acquires a form very much reminiscent
of the AMM decomposition formula for some model X into a pair of the BGW
models. At the same time, X, which still has to be found, is the pure gauge
limit of the elliptic Selberg integral. Presumably, it is again a BGW model,
only in the Dijkgraaf-Vafa double cut phase.Comment: 21 page
The matrix model version of AGT conjecture and CIV-DV prepotential
Recently exact formulas were provided for partition function of conformal
(multi-Penner) beta-ensemble in the Dijkgraaf-Vafa phase, which, if interpreted
as Dotsenko-Fateev correlator of screenings and analytically continued in the
number of screening insertions, represents generic Virasoro conformal blocks.
Actually these formulas describe the lowest terms of the q_a-expansion, where
q_a parameterize the shape of the Penner potential, and are exact in the
filling numbers N_a. At the same time, the older theory of CIV-DV prepotential,
straightforwardly extended to arbitrary beta and to non-polynomial potentials,
provides an alternative expansion: in powers of N_a and exact in q_a. We check
that the two expansions coincide in the overlapping region, i.e. for the lowest
terms of expansions in both q_a and N_a. This coincidence is somewhat
non-trivial, since the two methods use different integration contours:
integrals in one case are of the B-function (Euler-Selberg) type, while in the
other case they are Gaussian integrals.Comment: 27 pages, 1 figur
Ultrafast nonlocal control of spontaneous emission
Solid-state cavity quantum electrodynamics systems will form scalable nodes
of future quantum networks, allowing the storage, processing and retrieval of
quantum bits, where a real-time control of the radiative interaction in the
cavity is required to achieve high efficiency. We demonstrate here the dynamic
molding of the vacuum field in a coupled-cavity system to achieve the ultrafast
nonlocal modulation of spontaneous emission of quantum dots in photonic crystal
cavities, on a timescale of ~200 ps, much faster than their natural radiative
lifetimes. This opens the way to the ultrafast control of semiconductor-based
cavity quantum electrodynamics systems for application in quantum interfaces
and to a new class of ultrafast lasers based on nano-photonic cavities.Comment: 15 pages, 4 figure
Six-dimensional Supergravity and Projective Superfields
We propose a superspace formulation of N=(1,0) conformal supergravity in six
dimensions. The corresponding superspace constraints are invariant under
super-Weyl transformations generated by a real scalar parameter. The known
variant Weyl super-multiplet is recovered by coupling the geometry to a
super-3-form tensor multiplet. Isotwistor variables are introduced and used to
define projective superfields. We formulate a locally supersymmetric and
super-Weyl invariant action principle in projective superspace. Some families
of dynamical supergravity-matter systems are presented.Comment: 39 pages; v3: some modifications in section 2; equations (2.3),
(2.14b), (2.16) and (2.17) correcte
In-medium hadronic spectral functions through the soft-wall holographic model of QCD
We study the scalar glueball and vector meson spectral functions in a hot and
dense medium by means of the soft-wall holographic model of QCD. Finite
temperature and density effects are implemented through the AdS/RN metric. We
analyse the behaviour of the hadron masses and widths in the plane,
and compare our results with the experimental ones and with other theoretical
determinations.Comment: 16 pages, 6 figures. matching the published versio
Boundary Conditions and Unitarity: the Maxwell-Chern-Simons System in AdS_3/CFT_2
We consider the holography of the Abelian Maxwell-Chern-Simons (MCS) system
in Lorentzian three-dimensional asymptotically-AdS spacetimes, and discuss a
broad class of boundary conditions consistent with conservation of the
symplectic structure. As is well-known, the MCS theory contains a massive
sector dual to a vector operator in the boundary theory, and a topological
sector consisting of flat connections dual to U(1) chiral currents; the
boundary conditions we examine include double-trace deformations in these two
sectors, as well as a class of boundary conditions that mix the vector
operators with the chiral currents. We carefully study the symplectic product
of bulk modes and show that almost all such boundary conditions induce
instabilities and/or ghost excitations, consistent with violations of unitarity
bounds in the dual theory.Comment: 50+1 pages, 6 figures, PDFLaTeX; v2: added references, corrected
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Extreme Food-Plant Specialisation in Megabombus Bumblebees as a Product of Long Tongues Combined with Short Nesting Seasons
© 2015 Huang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. http://creativecommons.org/licenses/by/4.0/ The attached file is the published version of the article
Exacerbation of Bloody Diarrhea as a Side Effect of Mesalamine Treatment of Active Ulcerative Colitis
Mesalamine has been used as the first-line therapy for the treatment of ulcerative colitis (UC) because of its efficacy and fewer side effects. However, earlier study showed that mesalamine occasionally causes diarrhea. We are presenting a patient with active UC in whom bloody diarrhea accompanied by abdominal pain and fever occurred and the symptoms were aggravated after administration of mesalamine. In order to clarify the reason of symptoms aggravation, drug lymphocyte stimulation test and rechallenge trial with mesalamine were performed. The results indicated the possibility that aggravation was related to allergic reaction and was dose-dependent. Furthermore, we examined colonoscopic views but there was no remarkable change in before and after rechallenge trial. Based on the above result, the patient was diagnosed with mesalamine intolerance. In order to differentiate whether the exacerbation of bloody diarrhea is due to the side effects of the mesalamine or a true relapse of UC, taking careful history before and after increasing mesalamine dosage as well as being aware of side effects of mesalamine are required. Clinicians should be aware of diarrhea as a side effect of mesalamine particularly after onset of mesalamine formulation, change in mesalamine formulation, or change in mesalamine dose
Cell arrest and cell death in mammalian preimplantation development
The causes, modes, biological role and prospective significance of cell death in preimplantation development in humans and other mammals are still poorly understood. Early bovine embryos represent a very attractive experimental model for the investigation of this fundamental and important issue.
To obtain reference data on the temporal and spatial occurrence of cell death in early bovine embryogenesis, three-dimensionally preserved embryos of different ages and stages of development up to hatched blastocysts were examined in toto by confocal laser scanning microscopy. In parallel, transcript abundance profiles for selected apoptosis-related genes were analyzed by real-time reverse transcriptase-polymerase chain reaction. Our study documents that in vitro as well as in vivo, the first four cleavage cycles are prone to a high failure rate including different types of permanent cell cycle arrest and subsequent non-apoptotic blastomere death. In vitro produced and in vivo derived blastocysts showed a significant incidence of cell death in the inner cell mass (ICM), but only in part with morphological features of apoptosis. Importantly, transcripts for CASP3, CASP9, CASP8 and FAS/FASLG were not detectable or found at very low abundances.
In vitro and in vivo, errors and failures of the first and the next three cleavage divisions frequently cause immediate embryo death or lead to aberrant subsequent development, and are the main source of developmental heterogeneity. A substantial occurrence of cell death in the ICM even in fast developing blastocysts strongly suggests a regular developmentally controlled elimination of cells, while the nature and mechanisms of ICM cell death are unclear. Morphological findings as well as transcript levels measured for important apoptosis-related genes are in conflict with the view that classical caspase-mediated apoptosis is the major cause of cell death in early bovine development
Genes Suggest Ancestral Colour Polymorphisms Are Shared across Morphologically Cryptic Species in Arctic Bumblebees
email Suzanne orcd idCopyright: © 2015 Williams et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited
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