D=2+1 N=2 Yang-Mills Theory From Wrapped Branes

We find a new solution of Type IIB supergravity which represents a collection of D5 branes wrapped on the topologically non-trivial S^3 of the deformed conifold geometry T^*S^3. The Type IIB solution is obtained by lifting a new solution of D=7 SU(2)_L x SU(2)_R gauged supergravity to ten dimensions in which SU(2)_D gauge fields in the diagonal subgroup are turned on. The supergravity solution describes a slice of the Coulomb branch in the large N limit of N=2 SYM in three dimensions.Comment: 19 pages, 1figure, harvmac; expanded analysis of D=4 N=2 system in the appendix, references adde

Nota sobre las investigaciones que se están efectuando sobre los cambios del nivel del Mediterráneo

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Bagger-Lambert Theory for General Lie Algebras

We construct the totally antisymmetric structure constants f^{ABCD} of a 3-algebra with a Lorentzian bi-invariant metric starting from an arbitrary semi-simple Lie algebra. The structure constants f^{ABCD} can be used to write down a maximally superconformal 3d theory that incorporates the expected degrees of freedom of multiple M2 branes, including the "center-of-mass" mode described by free scalar and fermion fields. The gauge field sector reduces to a three dimensional BF term, which underlies the gauge symmetry of the theory. We comment on the issue of unitarity of the quantum theory, which is problematic, despite the fact that the specific form of the interactions prevent the ghost fields from running in the internal lines of any Feynman diagram. Giving an expectation value to one of the scalar fields leads to the maximally supersymmetric 3d Yang-Mills Lagrangian with the addition of two U(1) multiplets, one of them ghost-like, which is decoupled at large g_YM.Comment: 12 pages, Latex; small corrections and references added; published version (small typos fixed

Time-reversibility and integrability of p:-q resonant vector fields

We study local analytical integrability in a neighborhood of $p:-q$ resonant singular point of a two-dimensional vector field and its connection to time-reversibility with respect to the non-smooth involution $\varphi(x,y)=(y^{p/q},x^{q/p}).$ Some generalizations of the theory developed by K.~S.~Sibirsky for $1:-1$ resonant case to the $p:-q$ resonant case are presented

Living with ghosts in Lorentz invariant theories

We argue that theories with ghosts may have a long lived vacuum state even if all interactions are Lorentz preserving. In space-time dimension D = 2, we consider the tree level decay rate of the vacuum into ghosts and ordinary particles mediated by non-derivative interactions, showing that this is finite and logarithmically growing in time. For D > 2, the decay rate is divergent unless we assume that the interaction between ordinary matter and the ghost sector is soft in the UV, so that it can be described in terms of non-local form factors rather than point-like vertices. We provide an example of a nonlocal gravitational-strength interaction between the two sectors, which appears to satisfy all observational constraints.Comment: 17 pages, comments and references adde

Eukaryotic translation initiation factor 5A inhibition alters physiopathology and immune responses in a “humanized” transgenic mouse model of type 1 diabetes

Therapeutic options for treatment of type 1 diabetes (T1D) are still missing. New avenues for immune modulation need to be developed. Here we attempted at altering the diabetes outcome of our humanized model of T1D by inhibiting translation-initiation factor eIF5A hypusination in vivo. Double-transgenic (DQ8-GAD65) mice were immunized with adenoviral vectors carrying GAD65 for diabetes induction. Animals were subsequently treated with deoxyhypusine synthase (DHS) inhibitor GC7 and monitored for diabetes development over time. On one hand, helper CD4+ T cells were clearly affected by the downregulation of the eIF5A not just at the pancreas level but overall. On the other hand, the T regulatory cell component of CD4 responded with activation and proliferation significantly higher than in the non-GC7-treated controls. Female mice seemed to be more susceptible to these effects. All together, our results show for the first time that downregulation of eIF5A through inhibition of DHS altered the physiopathology and observed immune outcome of diabetes in an animal model that closely resembles human T1D. Although the development of diabetes could not be abrogated by DHS inhibition, the immunomodulatory capacity of this approach may supplement other interventions directed at increasing regulation of autoreactive T cells in T1D

Option pricing under stochastic volatility: the exponential Ornstein-Uhlenbeck model

We study the pricing problem for a European call option when the volatility of the underlying asset is random and follows the exponential Ornstein-Uhlenbeck model. The random diffusion model proposed is a two-dimensional market process that takes a log-Brownian motion to describe price dynamics and an Ornstein-Uhlenbeck subordinated process describing the randomness of the log-volatility. We derive an approximate option price that is valid when (i) the fluctuations of the volatility are larger than its normal level, (ii) the volatility presents a slow driving force toward its normal level and, finally, (iii) the market price of risk is a linear function of the log-volatility. We study the resulting European call price and its implied volatility for a range of parameters consistent with daily Dow Jones Index data.Comment: 26 pages, 6 colored figure

Flat deformation of a spacetime admitting two Killing fields

It is shown that given an analytic Lorentzian metric on a 4-manifold, $g$, which admits two Killing vector fields, then it exists a local deformation law $\eta = a g + b H$, where $H$ is a 2-dimensional projector, such that $\eta$ is flat and admits the same Killing vectors. We also characterize the particular case when the projector $H$ coincides with the quotient metric. We apply some of our results to general stationary axisymmetric spacetime