The Free Energy of N=4 Super-Yang-Mills and the AdS/CFT Correspondence

We compute the high-temperature limit of the free energy for four-dimensional N=4 supersymmetric SU(N_c) Yang-Mills theory. At weak coupling we do so for a general ultrastatic background spacetime, and in the presence of slowly-varying background gauge fields. Using Maldacena's conjectured duality, we calculate the strong-coupling large-N_c expression for the special case that the three-space has constant curvature. We compare the two results paying particular attention to curvature corrections to the leading order expressions.Comment: 26 pages.Minor corrections to eqs.(19),(21). Results and conclusions unchanged. References adde

PP-wave String Interactions from String Bit Model

We construct the string states $|O_{p}^J>_J$, $|O_{q}^{J_1}>_{{J_1}{J_2}}$ and $|O_{0}^{J_{1}J_{2}}>_{{J_1}{J_2}}$ in the Hilbert space of the quantum mechanical orbifold model so as to calculate the three point functions and the matrix elements of the light-cone Hamiltonian from the interacting string bit model. With these string states we show that the three point functions and the matrix elements of the Hamiltonian derived from the interacting string bit model up to $g^{2}_2$ order precisely match with those computed from the perturbative SYM theory in BMN limit.Comment: 20 pages, no figure, LaTeX, some changes made and references adde

DLCQ String Spectrum from N=2{\cal N}=2 SYM Theory

We study non planar corrections to the spectrum of operators in the ${\mathcal N}=2$ supersymmetric Yang Mills theory which are dual to string states in the maximally supersymmetric pp-wave background with a {\em compact} light-cone direction. The existence of a positive definite discrete light-cone momentum greatly simplifies the operator mixing problem. We give some examples where the contribution of all orders in non-planar diagrams can be found analytically. On the string theory side this corresponds to finding the spectrum of a string state to all orders in string loop corrections.Comment: 35 pages, no figure

Non-Abelian BIonic Brane Intersections

We study "fuzzy funnel" solutions to the non-Abelian equations of motion of the D-string. Our funnel describes n^6/360 coincident D-strings ending on n^3/6 D7-branes, in terms of a fuzzy six-sphere which expands along the string. We also provide a dual description of this configuration in terms of the world volume theory of the D7-branes. Our work makes use of an interesting non-linear higher dimensional generalization of the instanton equations.Comment: 17 pages uses harvmac; v2: small typos corrected, refs adde

Porphyrin-polymer nanocompartments: singlet oxygen generation and antimicrobial activity

A new water-soluble photocatalyst for singlet oxygen generation is presented. Its absorption extends to the red part of the spectrum, showing activity up to irradiation at 660 nm. Its efficiency has been compared to that of a commercial analogue (Rose Bengal) for the oxidation of L-methionine. The quantitative and selective oxidation was promising enough to encapsulate the photocatalyst in polymersomes. The singlet oxygen generated in this way can diffuse and remain active for the oxidation of L-methionine outside the polymeric compartment. These results made us consider the use of these polymersomes for antimicrobial applications. E. Coli colonies were subjected to oxidative stress using the photocatalyst-polymersome conjugates and nearly all the colonies were damaged upon extensive irradiation while under the same red LED light irradiation, liquid cultures in the absence of porphyrin or porphyrin-loaded polymersomes were unharme

Chiral primary cubic interactions from pp-wave supergravity

We explicitly construct cubic interaction light-cone Hamiltonian for the chiral primary system involving the metric fields and the self-dual four-form fields in the IIB pp-wave supergravity. The background fields representing pp-waves exhibit SO(4)*SO(4)*Z_2 invariance. It turns out that the interaction Hamiltonian is precisely the same as that for the dilaton-axion system, except for the fact that the chiral primary system fields have the opposite parity to that of the dilaton-axion fields under the Z_2 transformation that exchanges two SO(4)'s.Comment: 14 pages, A few comments are adde

Superstrings and D-branes in A Plane Wave

We carefully analyze the supersymmetry algebra of closed strings and open strings in a type IIB plane wave background. We use eight component chiral spinors, SO(8) Majorana-Weyl spinors, in light-cone gauge to provide a useful basis of string field theory calculation in the plane wave. We consider the two classes of D-branes, $D_\pm$-branes, and give a worldsheet derivation of conserved supercurrents for all half BPS D-branes preserving 16 supersymmetries in the type IIB plane wave background. We exhaustively provide the supersymmetry algebra of the half BPS branes as well. We also point out that the supersymmetry algebra distinguishes the two SO(4) directions with relative sign which is consistent with the Z_2 symmetry of the string action.Comment: v4: 28 pages, Latex, Worldsheet derivation of conserved supercurrents for all half BPS D-branes newly added, improved presentation and typo

Dynamical Stability of Six-Dimensional Warped Brane-Worlds

We study a generalization of the Randall-Sundrum mechanism for generating the weak/Planck hierarchy, which uses two rather than one warped extra dimension, and which requires no negative tension branes. A 4-brane with one exponentially large compact dimension plays the role of the Planck brane. We investigate the dynamical stability with respect to graviton, graviphoton and radion modes. The radion is shown to have a tachyonic instability for certain models of the 4-brane stress-energy, while it is stable in others, and massless in a special case. If stable, its mass is in the milli-eV range, for parameters of the model which solve the hierarchy problem. The radion is shown to couple to matter with gravitational strength, so that it is potentially detectable by submillimeter-range gravity experiments. The radion mass can be increased using a bulk scalar field in the manner of Goldberger and Wise, but only to order MeV, due to the effect of the large extra dimension. The model predicts a natural scale of 10^{13} GeV on the 4-brane, making it a natural setting for inflation from the ultraviolet brane.Comment: 28 pages, 7 figure

Porphyrin Containing Polymersomes with Enhanced ROS Generation Efficiency: in vitro evaluation

Abstract Porphyrins are molecules possessing unique photophysical properties making them suitable for application in photodynamic therapy. The incorporation of porphyrins into natural or synthetic nano-assemblies such as polymersomes is a strategy to improve and prolong their therapeutic capacities and to overcome their limitations as therapeutic and diagnostic agents. Here, 5,10,15,20-tetrakis(1-(6-ethoxy-6-oxohexyl)-4-pyridin-1-io)-21H,23H-porphyrin tetrabromide porphyrin is inserted into polymersomes in order to demonstrate that the encapsulation enhances its ability to generate highly reactive singlet oxygen (1O2) upon irradiation in vitro. The photoactivation of the free and polymersome-encapsulated porphyrin is evaluated by electron spin resonance and cell viability assays on three different mammalian cell lines. The results indicate that by encapsulating the porphyrin, a controlled ROS delivery within the cells is achieved, at the same time avoiding side effects such as dark toxicity, non-specific porphyrin release and over time decreased activity in vitro. This work focuses on showing a not-toxic model system for modern therapeutic nanomedicine, which works under mild irradiation and dosage conditions