Stable p-branes in Chern-Simons AdS supergravities

We construct static codimension-two branes in any odd dimension D, with negative cosmological constant, and show that they are exact solutions of Chern-Simons (super)gravity theory for (super)AdS coupled to external sources. The stability of these solutions is analyzed by counting the number of preserved supersymmetries. It is shown that static massive (D-3)-branes are unstable unless some suitable gauge fields are added and the brane is extremal. In particular, in three dimensions, a 0-brane is recognized as the negative mass counterpart of the BTZ black hole. For these 0-branes, we write explicitly electromagnetically charged BPS states with various number of preserved supersymmetries within the OSp(p|2) x OSp(q|2) supergroups. In five dimensions, we prove that stable 2-branes with electromagnetic charge always exist for the generic supergroup SU(2,2|N), where N is different than 4. For the special case N=4, in which the CS supergravity requires the addition of a nontrivial gauge field configuration in order to preserve maximal number of degrees of freedom, we show for two different static 2-branes that they are BPS states (one of which is the ground state), and from the corresponding algebra of charges we show that the energy is bounded from below. In higher dimensions, our results admit a straightforward generalization, although there are presumably more solutions corresponding to different intersections of the elementary objects.Comment: 43 pages, revtex4.cls; v2: slight amendments and references added to match published versio

Examining the prevalence of persistent postsurgical pain in pediatric spinal fusion surgery patients: a biopsychosocial approach

Thesis (M.A.)--Boston UniversityObjective: Despite extensive literature on chronic pain in surgical and nonsurgical adult patient populations and in the pediatric nonsurgical patient population, the acute to chronic postsurgical pain transition in children has been a largely neglected area of research. The purpose of this study was to examine the prevalence of persistent postsurgical pain in patients with adolescent idiopathic scoliosis who undergo spinal fusion surgery and to explore baseline differences between patients in varying longitudinal pain trajectories. Methods: The Scoliosis Research Society Questionnaire-30, which includes pain, self- image, mental health, and activity subscales, was administered to 219 patients at a large Northeast children’s hospital preoperatively and at one- and two-years postoperatively through their involvement in the Prospective Pediatric Scoliosis Study. A subset of these patients (n=77) also completed follow-up data at five-years post-surgery. Pain among this sample (in the past six months, in the past month, and at rest) was examined at each of the time points. Longitudinal pain trajectories were identified using the SAS PROC TRAJ procedure, and trajectory groups were compared for baseline differences in age, self-image, and mental health functioning through one-way analysis of variance and post- hoc analyses. Results: Preoperative pain was high in this sample, with 36% of patients prior to surgery reporting pain in the past month. The number of patients reporting pain in the past month postoperatively fell to 13% at one-year post-surgery but increased to 17% and 20% respectively at two- and five-years follow-up. A five-trajectory model emerged with a “no pain” group, a “pain improvement” group, a “short-term pain” group, a “delayed pain” group, and a “high pain” group with significant differences in baseline age (p<.01), self-image (p<.01), and mental health functioning (p<.01) found across groups. Conclusions: The study suggests that pediatric persistent postsurgical pain is potentially a significant health concern. This study also provides preliminary evidence that baseline psychosocial factors may contribute to patients’ longitudinal pain experiences postoperatively. Efforts should be taken to better understand the role that these predictors play in the emergence of persistent postsurgical pain in pediatric surgical patients and to explore how biological factors affect somatosensory phenotypes in this patient population

Preparing Youth for College and Career: A Process Evaluation of Urban Alliance

Urban Alliance, headquartered in Washington, DC, serves at-risk youth through its high school internship program, which provides training, mentoring, and work experience to high school seniors from distressed communities in Washington, DC; Baltimore; Northern Virginia; and Chicago. The program serves youth before they become disconnected, helping them successfully transition to higher education or employment after graduation. Urban Alliance has commissioned the Urban Institute to conduct a six-year, randomized controlled trial impact and process evaluation of its high school internship program. This report provides a process analysis of the program; the analysis is informed by extensive evaluator observation and interviews with staff, stakeholders, and youth. It also presents baseline information about Urban Alliance and the youth participating in its high school internship program in Washington, DC, and Baltimore in the 2011–12 and 2012–13 program years. Subsequent reports as part of the impact study will describe the early-adulthood impacts of the Urban Alliance internship program on the youth it serves. Below is a summary of the findings in this first of three reports

Let's Twist Again: General Metrics of G(2) Holonomy from Gauged Supergravity

We construct all complete metrics of cohomogeneity one G(2) holonomy with S^3 x S^3 principal orbits from gauged supergravity. Our approach rests on a generalization of the twisting procedure used in this framework. It corresponds to a non-trivial embedding of the special Lagrangian three-cycle wrapped by the D6-branes in the lower dimensional supergravity. There are constraints that neatly reduce the general ansatz to a six functions one. Within this approach, the Hitchin system and the flop transformation are nicely realized in eight dimensional gauged supergravity.Comment: 31 pages, latex; v2: minor changes, references adde

Silencing Citizen Protest: Local Environmental Resistance in the Land of Fires

The main topic of this case study is local community response to environmental contamination resulting from corruption and waste mismanagement. The field research was carried out in part of a massive Italian district colloquially referred to as the "land of fires” where illegal wastes dumped by the mafia routinely burned. A document analysis, participant observation and semi-structured interviews were conducted. Abandoned by those tasked with protecting public and environmental health, one might expect widespread concern, activism and protest. The case study supports the theory in terms of citizen mobilization while clarifying conditions that discourage public protest and action. The waste companies and the governmental institutions intended to regulate them were perceived as jointly complicit. Those who did not protest appeared to be caught in a classic double bind in which any response they made was wrong. Fear that the contamination and fires were harming their health demanded action. Yet, citizens dreaded that such efforts would bring mob and institutions' reprisal and did not have practical effective outcomes. This dilemma is fully explored, and the results are discussed within an eco-historical perspective. The case study is also updated to reflect more recent conditions that inspired widespread protest in the same affected region

Supersymmetric Electroweak Cosmic Strings

We study the connection between $N=2$ supersymmetry and a topological bound in a two-Higgs-doublet system with an $SU(2)\times U(1)_Y\times U(1)_{Y^{\prime}}$ gauge group. We derive the Bogomol'nyi equations from supersymmetry considerations showing that they hold provided certain conditions on the coupling constants, which are a consequence of the huge symmetry of the theory, are satisfied. Their solutions, which can be interpreted as electroweak cosmic strings breaking one half of the supersymmetries of the theory, are studied. Certain interesting limiting cases of our model which have recently been considered in the literature are finally analyzed.Comment: 20 pages, RevTe

Self-dual solitons in N=2 supersymmetric semilocal Chern-Simons theory

We embed the semilocal Chern-Simons-Higgs theory into an N=2 supersymmetric system. We construct the corresponding conserved supercharges and derive the Bogomol'nyi equations of the model from supersymmetry considerations. We show that these equations hold provided certain conditions on the coupling constants as well as on the Higgs potential of the system, which are a consequence of the huge symmetry of the theory, are satisfied. They admit string-like solutions which break one half of the supersymmetries --BPS Chern-Simons semilocal cosmic strings-- whose magnetic flux is concentrated at the center of the vortex. We study such solutions and show that their stability is provided by supersymmetry through the existence of a lower bound for the energy, even though the manifold of the Higgs vacuum does not contain non-contractible loops.Comment: 12 pages, LaTeX, no figures, to appear in Modern Physics Letters

Prepotential and Instanton Corrections in N=2 Supersymmetric SU(N_1)xSU(N_2) Yang Mills Theories

In this paper we analyse the non-hyperelliptic Seiberg-Witten curves derived from M-theory that encode the low energy solution of N=2 supersymmetric theories with product gauge groups. We consider the case of a SU(N_1)xSU(N_2) gauge theory with a hypermultiplet in the bifundamental representation together with matter in the fundamental representations of SU(N_1) and SU(N_2). By means of the Riemann bilinear relations that hold on the Riemann surface defined by the Seiberg--Witten curve, we compute the logarithmic derivative of the prepotential with respect to the quantum scales of both gauge groups. As an application we develop a method to compute recursively the instanton corrections to the prepotential in a straightforward way. We present explicit formulas for up to third order on both quantum scales. Furthermore, we extend those results to SU(N) gauge theories with a matter hypermultiplet in the symmetric and antisymmetric representation. We also present some non-trivial checks of our results.Comment: 21 pages, 2 figures, minor changes and references adde