Gravitating Opposites Attract

Generalizing previous work by two of us, we prove the non-existence of certain stationary configurations in General Relativity having a spatial reflection symmetry across a non-compact surface disjoint from the matter region. Our results cover cases such that of two symmetrically arranged rotating bodies with anti-aligned spins in $n+1$ ($n \geq 3$) dimensions, or two symmetrically arranged static bodies with opposite charges in 3+1 dimensions. They also cover certain symmetric configurations in (3+1)-dimensional gravity coupled to a collection of scalars and abelian vector fields, such as arise in supergravity and Kaluza-Klein models. We also treat the bosonic sector of simple supergravity in 4+1 dimensions.Comment: 13 pages; slightly amended version, some references added, matches version to be published in Classical and Quantum Gravit

E-Health Tools to Improve Antibiotic Use and Resistances: A Systematic Review

Background: e-Health tools, especially in the form of clinical decision support systems (CDSSs), have been emerging more quickly than ever before. The main objective of this systematic review is to assess the influence of these tools on antibiotic use for respiratory tract infections. (2) Methods: The scientific databases, MEDLINE-PubMed and EMBASE, were searched. The search was conducted by two independent researchers. The search strategy was mainly designed to identify relevant studies on the effectiveness of CDSSs in improving antibiotic use, as a primary outcome, and on the acceptability and usability of CDSSs, as a secondary outcome. (3) Results: After the selection, 22 articles were included. The outcomes were grouped either into antibiotics prescription practices or adherence to guidelines concerning antibiotics prescription. Overall, 15 out of the 22 studies had statistically significant outcomes related to the interventions. (4) Conclusions: Overall, the results show a positive impact on the prescription and conscientious use of antibiotics for respiratory tract infections, both with respect to patients and prescribing healthcare professionals. CDSSs have been shown to have great potential as powerful tools for improving both clinical care and patient outcomes

Multi-method Active Learning Approach: improving the educational experience in Pharmaceutical Drug Development

Improve educational experience, teaching effectiveness and learning outcomes remains one of the major educational challenges nowadays. Accordingly, our aim is to determine the effect of organizing and teaching the Pharmaceutical Drug Development unit using a Multi-method Active Learning Approach, MALA, as a novel teaching/learning strategy. MALA involved several different activities about pharmaceutical legislation, medicines production and validation process, Common Technical Document, and others, and the evaluation of this active learning approach was made in two ways: students’ performance (grades), and students’ evaluation regarding the curricular unit and the teachers’ performance. Results revealed two main important aspects of the implementation of MALA: (i) the implementation of MALA showed high rates of students’ satisfaction regarding the curricular unit and teachers’ performance; (ii) student’s performance (grades) were very high, revealing excellent teaching/ learning results. In conclusion, the present study fostered the concept that the MALA- learning approach should contribute to knowledge- enhancing in the pharmaceutical practice and could encourage integration of the students´ learning skills in the future career, thus stimulating the flexibility in learning.publishe

Primordial black holes from cosmic necklaces

Cosmic necklaces are hybrid topological defects consisting of monopoles and strings. We argue that primordial black holes(PBHs) may have formed from loops of the necklaces, if there exist stable winding states, such as coils and cycloops. Unlike the standard scenario of PBH formation from string loops, in which the kinetic energy plays important role when strings collapse into black holes, the PBH formation may occur in our scenario after necklaces have dissipated their kinetic energy. Then, the significant difference appears in the production ratio. In the standard scenario, the production ratio $f$ becomes a tiny fraction $f\sim 10^{-20}$, however it becomes $f \sim 1$ in our case. On the other hand, the typical mass of the PBHs is much smaller than the standard scenario, if they are produced in the same epoch. As the two mechanisms may work at the same time, the necklaces may have more than one channel of the gravitational collapse. Although the result obtained in this paper depends on the evolution of the dimensionless parameter $r$, the existence of the winding state could be a serious problem in some cases. Since the existence of the winding state in brane models is due to the existence of a non-tivial circle in the compactified space, the PBH formation can be used to probe the structure of the compactified space. Black holes produced by this mechanism may have peculiar properties.Comment: 22pages, 3 figures, added many comments, +1 figure, accepted for publication in JHE

On a class of 4D Kahler bases and AdS_5 supersymmetric Black Holes

We construct a class of toric Kahler manifolds, M_4, of real dimension four, a subset of which corresponds to the Kahler bases of all known 5D asymptotically AdS_5 supersymmetric black-holes. In a certain limit, these Kahler spaces take the form of cones over Sasaki spaces, which, in turn, are fibrations over toric manifolds of real dimension two. The metric on M_4 is completely determined by a single function H(x), which is the conformal factor of the two dimensional space. We study the solutions of minimal five dimensional gauged supergravity having this class of Kahler spaces as base and show that in order to generate a five dimensional solution H(x) must obey a simple sixth order differential equation. We discuss the solutions in detail, which include all known asymptotically AdS_5 black holes as well as other spacetimes with non-compact horizons. Moreover we find an infinite number of supersymmetric deformations of these spacetimes with less spatial isometries than the base space. These deformations vanish at the horizon, but become relevant asymptotically.Comment: 34 pages, 3 figures. v2: formula (8.35) and other minor typos corrected; references added; accepted for publication in JHE

G\"{o}del black hole, closed timelike horizon, and the study of particle emissions

We show that a particle, with positive orbital angular momentum, following an outgoing null/timelike geodesic, shall never reach the closed timelike horizon (CTH) present in the $(4+1)$-dimensional rotating G\"{o}del black hole space-time. Therefore a large part of this space-time remains inaccessible to a large class of geodesic observers, depending on the conserved quantities associated with them. We discuss how this fact and the existence of the closed timelike curves present in the asymptotic region make the quantum field theoretic study of the Hawking radiation, where the asymptotic observer states are a pre-requisite, unclear. However, the semiclassical approach provides an alternative to verify the Smarr formula derived recently for the rotating G\"{o}del black hole. We present a systematic analysis of particle emissions, specifically for scalars, charged Dirac spinors and vectors, from this black hole via the semiclassical complex path method.Comment: 13 pages; minor changes, references adde

Numerical relativity in higher dimensions

We give a status report on our project targeted at performing numerical simulations of a head-on collision of non-spinning black holes in higher dimensional non-compact space-times. These simulations should help us understand black objects in higher dimensions and their stability properties. They are also relevant for the problem of black hole formation and evaporation in particle accelerators and cosmic rays. We use the symmetries of the system to reduce the problem to an effective 3+1 problem, allowing the use of existing numerical codes. As a simple application of the formalism, we present the results for the evolution of a five dimensional single black hole space-time. © 2010 IOP Publishing Ltd

Classical and Quantum Strings in compactified pp-waves and Godel type Universes

We consider Neveu-Schwarz pp-waves with spacetime supersymmetry. Upon compactification of a spacelike direction, these backgrounds develop Closed Null Curves (CNCs) and Closed Timelike Curves (CTCs), and are U-dual to supersymmetric Godel type universes. We study classical and quantum strings in this background, with emphasis on the strings winding around the compact direction. We consider two types of strings: long strings stabilized by NS flux and rotating strings which are stabilized against collapse by angular momentum. Some of the latter strings wrap around CNCs and CTCs, and are thus a potential source of pathology. We analyze the partition function, and in particular discuss the effects of these string states. Although our results are not conclusive, the partition function seems to be dramatically altered due to the presence of CNCs and CTCs. We discuss some interpretations of our results, including a possible sign of unitary violation.Comment: 42 pages, LaTeX, 2 figure

Formation of monopoles and domain walls after brane inflation

We study cosmological defect formation after brane inflation. The cosmological defects are corresponding to the branes that have less than three spacial dimensions in the uncompactified spacetime. Contrary to the previous arguments, production of monopoles and domain walls are not always negligible. Monopoles and domain walls are formed by the branes extended between mother branes.Comment: 27pages, 7 figures, many comments, footnotes and reviews are added, to appear in JHE

New generalized nonspherical black hole solutions

We present numerical evidence for the existence of several types of static black hole solutions with a nonspherical event horizon topology in $d\geq 6$ spacetime dimensions. These asymptotically flat configurations are found for a specific metric ansatz and can be viewed as higher dimensional counterparts of the $d=5$ static black rings, dirings and black Saturn. Similar to that case, they are supported against collapse by conical singularities. The issue of rotating generalizations of these solutions is also considered.Comment: 47 pages, 11 figures, some comments adde