Instanton Corrected Non-Supersymmetric Attractors

We discuss non-supersymmetric attractors with an instanton correction in Type IIA string theory compactified on a Calabi-Yau three-fold at large volume. For a stable non-supersymmetric black hole, the attractor point must minimize the effective black hole potential. We study the supersymmetric as well as non-supersymmetric attractors for the D0-D4 system with instanton corrections. We show that in simple models, like the STU model, the flat directions of the mass matrix can be lifted by a suitable choice of the instanton parameters.Comment: Minor modifications, Corrected typos, 38 pages, 1 figur

Non-supersymmetric extremal multicenter black holes with superpotentials

Using the superpotential approach we generalize Denef's method of deriving and solving first-order equations describing multicenter extremal black holes in four-dimensional N = 2 supergravity to allow non-supersymmetric solutions. We illustrate the general results with an explicit example of the stu model.Comment: 17 pages, v2: some clarifications adde

The Nuts and Bolts of Einstein-Maxwell Solutions

We find new non-supersymmetric solutions of five-dimensional ungauged supergravity coupled to two vector multiplets. The solutions are regular, horizonless and have the same asymptotic charges as non-extremal charged black holes. An essential ingredient in our construction is a four-dimensional Euclidean base which is a solution to Einstein-Maxwell equations. We construct stationary solutions based on the Euclidean dyonic Reissner-Nordstrom black hole as well as a six-parameter family with a dyonic Kerr-Newman-NUT base. These solutions can be viewed as compactifications of eleven-dimensional supergravity on a six-torus and we discuss their brane interpretation.Comment: 29 pages, 3 figure

Multi-Centered Black Hole Flows

We describe the systematical construction of the first order formalism for multi-centered black holes with flat three dimensional base-space, within the so-called $T^{3}$ model of N=2, D=4 ungauged Maxwell-Einstein supergravity. The three possible flow classes (BPS, composite non-BPS and almost-BPS) are analyzed in detail, and various solutions, such as single-centered (static or under-rotating) and all known multi-centered black holes, are recovered in this unified framework. We also consider the possibility of obtaining new solutions. The almost-BPS class is proved to split into two general sub-classes, corresponding to a positive or negative value of the duality-invariant polynomial for the total charge; the well known almost BPS system is shown to be a particular solution of the second sub-class.Comment: 17 pages,no figure

Duality covariant non-BPS first order systems

We study extremal black hole solutions to four dimensional N=2 supergravity based on a cubic symmetric scalar manifold. Using the coset construction available for these models, we define the first order flow equations implied by the corresponding nilpotency conditions on the three-dimensional scalar momenta for the composite non-BPS class of multi-centre black holes. As an application, we directly solve these equations for the single-centre subclass, and write the general solution in a manifestly duality covariant form. This includes all single-centre under-rotating non-BPS solutions, as well as their non-interacting multi-centre generalisations.Comment: 31 pages, v2: Discussion of the quadratic constraint clarified, references added, typos corrected, published versio

Improving healthcare delivery with new interactive visualization methods

Over the last years, the implementation and evolution of computer resources in hospital institutions has been improving both the financial and temporal efficiency of clinical processes, as well as the security in the transmission and maintenance of their data, also ensuring the reduction of clinical risk. Diagnosis, treatment and prevention of human illness are some of the most information-intensive of all intellectual tasks. Health providers often do not have or cannot find the information they need to respond quickly and appropriately to patient’s medical problems. Failure to review and follow up on patient’s test results in a timely manner, for example, represents a patient’s safety and malpractice concern. Therefore, it was sought to identify problems in a medical exams results management system and possible ways to improve this system in order to reduce both clinical risks and hospital costs. In this sense, a new medical exams visualization platform (AIDA-MCDT) was developed, specifically in the Hospital Center of Porto (CHP), with several new functionalities in order to make this process faster, intuitive and efficient, always guaranteeing the confidentiality and protection of patients’ personal data and significantly improving the usability of the system, leading to a better health care delivery.FCT - Fundação para a Ciência e a Tecnologia (UID/CEC/00319/2019

First-order flows and stabilisation equations for non-BPS extremal black holes

We derive a generalised form of flow equations for extremal static and rotating non-BPS black holes in four-dimensional ungauged N = 2 supergravity coupled to vector multiplets. For particular charge vectors, we give stabilisation equations for the scalars, analogous to the BPS case, describing full known solutions. Based on this, we propose a generic ansatz for the stabilisation equations, which surprisingly includes ratios of harmonic functions.Comment: 27 pages; v2: presentation improved and references added as in the published versio

The extremal black holes of N=4 supergravity from so(8,2+n) nilpotent orbits

We consider the stationary solutions of N=4 supergravity coupled to n vector multiplets that define linear superpositions of non-interacting extremal black holes. The most general solutions of this type are derived from the graded decompositions of so(8,2+n) associated to its nilpotent orbits. We illustrate the formalism by giving explicitly asymptotically Minkowski non-BPS solutions of the most exotic class depending on 6+n harmonic functions.Comment: Corrected version for publication, references adde

Emission from the D1D5 CFT: Higher Twists

We study a certain class of nonextremal D1D5 geometries and their ergoregion emission. Using a detailed CFT computation and the formalism developed in arXiv:0906.2015 [hep-th], we compute the full spectrum and rate of emission from the geometries and find exact agreement with the gravity answer. Previously, only part of the spectrum had been reproduced using a CFT description. We close with a discussion of the context and significance of the calculation.Comment: 39 pages, 6 figures, late

Supergravity Solutions from Floating Branes

We solve the equations of motion of five-dimensional ungauged supergravity coupled to three U(1) gauge fields using a floating-brane Ansatz in which the electric potentials are directly related to the gravitational warp factors. We find a new class of non-BPS solutions, that can be obtained linearly starting from an Euclidean four-dimensional Einstein-Maxwell base. This class - the largest known so far - reduces to the BPS and almost-BPS solutions in certain limits. We solve the equations explicitly when the base space is given by the Israel-Wilson metric, and obtain solutions describing non-BPS D6 and anti-D6 branes kept in equilibrium by flux. We also examine the action of spectral flow on solutions with an Israel-Wilson base and show that it relates these solutions to almost-BPS solutions with a Gibbons-Hawking base.Comment: 24 pages, 1 figur