Circular Semiclassical String solutions on Confining AdS/CFT Backgrounds

We study multiwrapped circular string pulsating in the radial direction of AdS black hole. We compute the energy of this string as a function of a large quantum number n. One then could associate it with energy and a quantum number of states in the dual finite temperature {\cal N}=4 SYM theory as well as three dimensional pure gauge theory. We observe that the n dependence of the energy has a universal form. We have also considered pulsating string in the background of the near-extremal D4-brane solution. Circular pulsating membrane in M-theory on AdS_7\times S^4 has also been studied.Comment: 14 pages, latex, v2: typos corrected, refs. adde

The effect of lipopolysaccharide on the expression level of immunomodulatory and immunostimulatory factors of human amniotic epithelial cells

Objective Human amniotic epithelial cells (hAECs) are a novel source of stem cells and have immunomodulatory effects on both the innate and adoptive immune system. hAECs can differentiate into multiple cell lineages that make them a suitable cell source for regenerative medicine. These cells express multiple toll-like receptors (TLRs) and respond to various TLR ligands. This study aimed to evaluate the effect of lipopolysaccharide (LPS), a TLR4 ligand, on the level of immunomodulatory and immunostimulatory factors of hAECs. Results Our results indicated that LPS had the ability to up-regulate the expression of prostaglandin E2 synthase and transforming growth factor-beta1 in hAECs. However, there was no change in the level of interleukin-1beta, interleukin-6 and interleukin-10 in hAECs when were stimulated with LPS. In addition, we observed tumor necrosis factor-alpha was only expressed at very low level in some of hAECs samples which its expression was independent of the effects of LPS. Keywords: Human amniotic epithelial cells Toll-like receptors Lipopolysaccharide Immunomodulatory effects Regenerative medicin

On Effective Superpotentials and Compactification to Three Dimensions

We study four dimensional N=2 SO/SP supersymmetric gauge theory on R^3\times S^1 deformed by a tree level superpotential. We will show that the exact superpotential can be obtained by making use of the Lax matrix of the corresponding integrable model which is the periodic Toda lattice. The connection between vacua of SO(2N) and SO(2kN-2k+2) can also be seen in this framework. Similar analysis can also be applied for SO(2N+1) and SP(2N).Comment: 18 pages, latex file, v2: typos corrected, refs adde

BPS R-balls in N=4 SYM on R X S^3, Quantum Hall Analogy and AdS/CFT Holography

In this paper, we propose a new approach to study the BPS dynamics in N=4 supersymmetric U(N) Yang-Mills theory on R X S^3, in order to better understand the emergence of gravity in the gauge theory. Our approach is based on supersymmetric, space-filling Q-balls with R-charge, which we call R-balls. The usual collective coordinate method for non-topological scalar solitons is applied to quantize the half and quarter BPS R-balls. In each case, a different quantization method is also applied to confirm the results from the collective coordinate quantization. For finite N, the half BPS R-balls with a U(1) R-charge have a moduli space which, upon quantization, results in the states of a quantum Hall droplet with filling factor one. These states are known to correspond to the ``sources'' in the Lin-Lunin-Maldacena geometries in IIB supergravity. For large N, we find a new class of quarter BPS R-balls with a non-commutativity parameter. Quantization on the moduli space of such R-balls gives rise to a non-commutative Chern-Simons matrix mechanics, which is known to describe a fractional quantum Hall system. In view of AdS/CFT holography, this demonstrates a profound connection of emergent quantum gravity with non-commutative geometry, of which the quantum Hall effect is a special case.Comment: 42 pages, 2 figures; v3: a new paragraph on counting unbroken susy of NC R-balls and references adde

Dual Spikes; New Spiky String Solutions

We find a new class of spiky solutions for closed strings in flat, $AdS_3\subset AdS_5$ and $R\times S^2(\subset S^5)$ backgrounds. In the flat case the new solutions turn out to be T-dual configurations of spiky strings found by Kruczenski hep-th/0410226. In the case of solutions living in $AdS$, we make a semi classical analysis by taking the large angular momentum limit. The anomalous dimension for these dual spikes is similar to that for rotating and pulsating circular strings in AdS with angular momentum playing the role of the level number. This replaces the well known logarithmic dependence for spinning strings. For the dual spikes living on sphere we find that no large angular momentum limit exists.Comment: Added reference

Conformal SO(2,4) Transformations for the Helical AdS String Solution

By applying the conformal SO(2,4) transformations to the folded rotating string configuration with two spins given by a certain limit from the helical string solution in AdS_3 x S^1, we construct new string solutions whose energy-spin relations are characterized by the boost parameter. When two SO(2,4) transformations are performed with two boost parameters suitably chosen, the straight folded rotating string solution with one spin in AdS_3 is transformed in the long string limit into the long spiky string solution whose expression is given from the helical string solution in AdS_3 by making a limit that the modulus parameter becomes unity.Comment: 16 pages, LaTex, no figure

N=1 G_2 SYM theory and Compactification to Three Dimensions

We study four dimensional N=2 G_2 supersymmetric gauge theory on R^3\times S^1 deformed by a tree level superpotential. We will show that the exact superpotential can be obtained by making use of the Lax matrix of the corresponding integrable model which is the periodic Toda lattice based on the dual of the affine G_2 Lie algebra. At extrema of the superpotential the Seiberg-Witten curve typically factorizes, and we study the algebraic equations underlying this factorization. For U(N) theories the factorization was closely related to the geometrical engineering of such gauge theories and to matrix model descriptions, but here we will find that the geometrical interpretation is more mysterious. Along the way we give a method to compute the gauge theory resolvent and a suitable set of one-forms on the Seiberg-Witten curve. We will also find evidence that the low-energy dynamics of G_2 gauge theories can effectively be described in terms of an auxiliary hyperelliptic curve.Comment: 27 pages, late

On the anatomy of multi-spin magnon and single spike string solutions

We study rigid string solutions rotating in $AdS_5\times S^5$ background. For particular values of the parameters of the solutions we find multispin solutions corresponding to giant magnons and single spike strings. We present an analysis of the dispersion relations in the case of three spin solutions distributed only in $S^5$ and the case of one spin in $AdS_5$ and two spins in $S^5$. The possible relation of these string solutions to gauge theory operators and spin chains are briefly discussed.Comment: 45 pages, the presentation rearranged in 3 sections, results unchanged, references added, some typos correcte

One entropy function to rule them all

We study the entropy of extremal four dimensional black holes and five dimensional black holes and black rings is a unified framework using Sen's entropy function and dimensional reduction. The five dimensional black holes and black rings we consider project down to either static or stationary black holes in four dimensions. The analysis is done in the context of two derivative gravity coupled to abelian gauge fields and neutral scalar fields. We apply this formalism to various examples including $U(1)^3$ minimal supergravity.Comment: 29 pages, 2 figures, revised version for publication, details adde

Semiclassical String Solutions on deformed NS5-brane Backgrounds and New Plane wave

We study different Penrose limits of supergravity solution of NS5-brane in the presence of RR field. Although in the case of NS5-brane we get a 4-dimensional plane wave, in the case with RR field we will get two different plane waves; a 4-dimensional and a 3-dimensional one. These plane wave solutions are the backgrounds that a particular string solution feels at one loop approximation. Using the one loop correction one can identify a particular subsector of LST/deformed LST which is dual to type II string theories on these plane waves.Comment: 18 pages, latex, v2: Minor changes, typos correcte