Fearless: Kevin Lugo

This summer, recent graduate Kevin Lugo will bike over 4,000 miles across the country to benefit the Ulman Cancer Fund for Young Adults. His choice to bike for seventy days from Baltimore to Seattle makes him fearless! His goal is to raise $7,476 for the organization, and he reached that goal last night (although more donations are always welcome in support of fighting cancer)! Kevin explains that when he studied abroad in Denmark in the fall of 2011, he “fell in love with sustainable transportation, especially cycling.” Not only does his fearless endeavor raise money to fight cancer, but he is also supporting healthy environmental practices. [excerpt

Renewable Resource Extraction: Experimental Analysis of Resource Management Policies Under Assumptions of Resource Migration

This paper presents research using a spatially explicit and dynamic common pool resource experiment to compare renewable resource extraction behavior between four treatments combining (1) open access and sole ownership institutions with (2) mobility and non-mobility of the renewable resource. The primary purpose of this research is to test the theory that introducing resource mobility into a sole ownership regime will remove the incentive for subjects to maximize the resource, instead causing them to revert to the myopic strategy predicted for the open access regime. I also test the hypothesis that open access firms are indifferent to resource dispersal. The results show that efficiency is unaffected by dispersal but the behavior of sole owners differs between dispersal conditions. Extraction requests increase at a faster rate under dispersal, fewer tokens remain unextracted in the final period, and some subjects show strategic behavior resulting in greater than 100% efficiency. This is a pilot study that presents preliminary evidence of a behavioral change. The results are subject to experimental factors such as subject misperceptions of linearity and statistical significance suffers from a small subject pool

Holographic phase transition from dyons in an AdS black hole background

We construct a dyon solution for a Yang-Mills-Higgs theory in a 4 dimensional Schwarzschild-anti-de Sitter black hole background with temperature T. We then apply the AdS/CFT correspondence to describe the strong coupling regime of a 2+1 quantum field theory which undergoes a phase transition exhibiting the condensation of a composite charge operator below a critical temperature $T_c$.Comment: 19 pages, 7 figures. Minor corrections, references added. Version published in JHEP

Space-time filling branes in non critical (super) string theories

We consider solutions of (super) gravities associated to non-critical (super) string theories in arbitrary space-time dimension D=p+3, that describe generically non extremal black p-branes charged under NSNS or RR gauge fields, embedded in some non critical vacuum. In the case of vacuum (uncharged) backgrounds, we solve completely the problem obtaining all the possible solutions, that consist of the (p+1)-dimensional Minkowski space times a linear dilaton times a S^1, and a three parameter family of solutions that include (p+1)-dimensional Minkowski space times the cigar, and its T-dual (p+1)-dimensional Minkowski space times the trumpet. For NSNS charged solutions, we also solve in closed form the problem, obtaining several families of solutions, that include in particular the fundamental non-critical string solution embedded in the cigar vacuum, recently found in hep-th/0604202, a solution that we interpret as a fundamental non-critical string embedded in the linear dilaton vacuum, and a two-parameter family of regular curvature solutions asymptotic to AdS_{1,2}\times S^1. In the case of RR charged Dp-branes solutions, an ansatz allows us to find a non conformal, constant curvature, asymptotically AdS_{1,p+1} space, T-dual to AdS_{1,p+2}, together with a two-parameter family of solutions that includes the non conformal, AdS black hole like solution associated with the earlier space. The solutions obtained by T-duality are Einstein spaces consisting of a two-parameter family of conformal, constant dilaton solutions, that include, in particular, the AdS black hole of hep-th/0403254. We speculate about the possible applications of some of them in the framework of the gauge-gravity correspondence.Comment: 34 pages, 10 figures, to be published by Nuclear Physics

The fundamental non critical string

We obtain the (super) gravity solution in arbitrary space-time dimension less than ten, that gives a low energy description of a fundamental string embedded in a non critical vacuum, product of $d$-dimensional Minkowski space-time and a cigar-like geometry with scale $r_0$. This solution, one of the few known examples of objects doubly localized, both at the origin of the transverse space as well as at the tip of the cigar, is determined by its charge $Q$ under the Kalb-Ramond gauge field $B$, and presumably preserves, for even $d$, $2^\frac{d}{2}$ supercharges. Moreover, we show that the solution is reliable at least in a region far away from both origins, as it is the case with the well known branes of critical string theory.Comment: 10 pages, latex file, one figure, to be published in Physics Letters

Gravitating sphalerons and sphaleron black holes in asymptotically anti-de Sitter spacetime

Numerical arguments are presented for the existence of spherically symmetric regular and black hole solutions of the EYMH equations with a negative cosmological constant. These solutions approach asymptotically the anti-de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. The instability of the gravitating sphaleron solutions is also proven.Comment: 30 pages, LaTeX, 8 Encapsulated PostScript figure

Gauge invariant perturbation theory and non-critical string models of Yang-Mills theories

We carry out a gauge invariant analysis of certain perturbations of $D-2$-branes solutions of low energy string theories. We get generically a system of second order coupled differential equations, and show that only in very particular cases it is possible to reduce it to just one differential equation. Later, we apply it to a multi-parameter, generically singular family of constant dilaton solutions of non-critical string theories in $D$ dimensions, a generalization of that recently found in arXiv:0709.0471[hep-th]. According to arguments coming from the holographic gauge theory-gravity correspondence, and at least in some region of the parameters space, we obtain glue-ball spectra of Yang-Mills theories in diverse dimensions, putting special emphasis in the scalar metric perturbations not considered previously in the literature in the non critical setup. We compare our numerical results to those studied previously and to lattice results, finding qualitative and in some cases, tuning properly the parameters, quantitative agreement. These results seem to show some kind of universality of the models, as well as an irrelevance of the singular character of the solutions. We also develop the analysis for the T-dual, non trivial dilaton family of solutions, showing perfect agreement between them.Comment: A new reference added