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

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

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

Gravitating Instantons In 3 Dimensions

We study the Einstein-Chern-Simons gravity coupled to Yang-Mills-Higgs theory in three dimensional Euclidean space with cosmological constant. The classical equations reduce to Bogomol'nyi type first order equations in curved space. There are BPS type gauge theory instanton (monopole) solutions of finite action in a gravitational instanton which itself has a finite action. We also discuss gauge theory instantons in the vacuum (zero action) AdS space. In addition we point out to some exact solutions which are singular.Comment: 17 pages, 4 figures, title has changed, gravitational instanton actions are adde

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

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

Monopoles, Dyons and Black Holes in the Four-Dimensional Einstein-Yang-Mills Theory

A continuum of monopole, dyon and black hole solutions exist in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space. Their structure is studied in detail. The solutions are classified by non-Abelian electric and magnetic charges and the ADM mass. The stability of the solutions which have no node in non-Abelian magnetic fields is established. There exist critical spacetime solutions which terminate at a finite radius, and have universal behavior. The moduli space of the solutions exhibits a fractal structure as the cosmological constant approaches zero.Comment: 36 Pages, 16 Figures. Minor typos corrected and one figure modifie

Combining Simulation Tools for End-to-End Trajectory Optimization

Trajectory simulations with advanced optimization algorithms are invaluable tools in the process of designing spacecraft. Due to the need for complex models, simulations are often highly tailored to the needs of the particular program or mission. NASA's Orion and SLS programs are no exception. While independent analyses are valuable to assess individual spacecraft capabilities, a complete end-to-end trajectory from launch to splashdown maximizes potential performance and ensures a continuous solution. In order to obtain end-to-end capability, Orion's in-space tool (Copernicus) was made to interface directly with the SLS's ascent tool (POST2) and a new tool to optimize the full problem by operating both simulations simultaneously was born

Preparação de sabão com propriedades fitoterápicas e emolientes a partir do óleo vegetal de cozinha.

Diariamente são descartados litros e litros de óleo doméstico usado, uma parte desse descarte se dá em latas de lixo, rede de esgoto, poucos são aqueles que reservam esse tipo de material para reciclagem, uma parte é por não saber como tratar os resíduos contidos em seu meio. Os projetos de preparação de sabão com propriedades fitoterápicas têm por objetivo dar um destino ao descarte desse óleo residual doméstico, promovendo a interação da comunidade local da região da Vila C a fazer desde a parte do tratamento de resíduo do óleo até a mistura de outros reagentes para a produção de um sabão para o banho de animais domésticos e que possa ser utilizável para limpeza de utensílios domésticos. Para a preparação deste material é considerado o fácil acesso aos reagentes envolvidos como a soda cáustica, a qual ainda é comercialmente vendida em mercearias locais e acesso às plantas medicinais que já tem suas propriedades conhecidas, como no caso a erva baleeira, calêndula, e citronela, também é realizado junto a comunidade, oficinas informando sobre os cuidados em manipular produtos químicos, como agir em caso de acidentes durante o manuseio, a quem é indicado a fazer esse tipo de tratamento e como preparar o produto. Existem análises laboratoriais que são acompanhadas e orientadas, as quais são necessárias para testes em pequena escala antes de cada oficina, essas análises são feitas para poder corrigir o pH do produto e mensurar a quantidade de aditivos na produção do sabão, após essas análises o modelo de produção é replicado em escala maior, já com a certeza dos resultados na qualidade do produto final. Desta forma se faz necessário uma investigação mais detalhada ao produto final, por meio de utilização de equipamentos cromatográficos e espectrofotômetros, como ferramenta na identificação dos compostos e/ou princípios ativos na composição, os quais dão a característica de fitoterápicos e comparar desta forma, com o que já temos em literatura conhecida

Strain- and Adsorption-Dependent Electronic States and Transport or Localization in Graphene

The chapter generalizes results on influence of uniaxial strain and adsorption on the electron states and charge transport or localization in graphene with different configurations of imperfections (point defects): resonant (neutral) adsorbed atoms either oxygen- or hydrogen-containing molecules or functional groups, vacancies or substitutional atoms, charged impurity atoms or molecules, and distortions. To observe electronic properties of graphene-admolecules system, we applied electron paramagnetic resonance technique in a broad temperature range for graphene oxides as a good basis for understanding the electrotransport properties of other active carbons. Applied technique allowed observation of possible metal-insulator transition and sorption pumping effect as well as discussion of results in relation to the granular metal model. The electronic and transport properties are calculated within the framework of the tight-binding model along with the Kubo-Greenwood quantum-mechanical formalism. Depending on electron density and type of the sites, the conductivity for correlated and ordered adsorbates is found to be enhanced in dozens of times as compared to the cases of their random distribution. In case of the uniaxially strained graphene, the presence of point defects counteracts against or contributes to the band-gap opening according to their configurations. The band-gap behaviour is found to be nonmonotonic with strain in case of a simultaneous action of defect ordering and zigzag deformation. The amount of localized charge carriers (spins) is found to be correlated with the content of adsorbed centres responsible for the formation of potential barriers and, in turn, for the localization effects. Physical and chemical states of graphene edges, especially at a uniaxial strain along one of them, play a crucial role in electrical transport phenomena in graphene-based materials.Comment: 16 pages, 10 figure