Numerical simulations of single and binary black holes in scalar-tensor theories: circumventing the no-hair theorem

Scalar-tensor theories are a compelling alternative to general relativity and one of the most accepted extensions of Einstein's theory. Black holes in these theories have no hair, but could grow "wigs" supported by time-dependent boundary conditions or spatial gradients. Time-dependent or spatially varying fields lead in general to nontrivial black hole dynamics, with potentially interesting experimental consequences. We carry out a numerical investigation of the dynamics of single and binary black holes in the presence of scalar fields. In particular we study gravitational and scalar radiation from black-hole binaries in a constant scalar-field gradient, and we compare our numerical findings to analytical models. In the single black hole case we find that, after a short transient, the scalar field relaxes to static configurations, in agreement with perturbative calculations. Furthermore we predict analytically (and verify numerically) that accelerated black holes in a scalar-field gradient emit scalar radiation. For a quasicircular black-hole binary, our analytical and numerical calculations show that the dominant component of the scalar radiation is emitted at twice the binary's orbital frequency.Comment: 21 pages, 6 figures, matches version accepted in Physical Review

Extremal black brane solutions in five-dimensional gauged supergravity

We study stationary black brane solutions in the context of N = 2, U(1) gauged supergravity in five dimensions. Using the formalism of first-order flow equations, we construct examples of extremal black brane solutions that include Nernst branes, i.e. extremal black brane solutions with vanishing entropy density, as well as black branes with cylindrical horizon topology, whose entropy density can be computed from a Cardy formula of the dual CFT.Comment: 37 pages, 5 figures, v2: Added references and derivation of the first-order flow equations from a superpotential, version which appeared in JHE

Quantum corrections to extremal black brane solutions

We discuss quantum corrections to extremal black brane solutions in N=2 U(1) gauged supergravity in four dimensions. We consider modifications due to a certain class of higher-derivative terms as well as perturbative corrections to the prepotential. We use the entropy function formalism to assess the impact of these corrections on singular brane solutions and we give a few examples. We then use first-order flow equations to construct solutions that interpolate between quantum corrected fixed points of the associated potentials.Comment: 30 pages, 10 figures; v2: references added, as well as a discussion about how to obtain the attractor equations by extremizing an effective potential, coincides with published versio

Intestinal Barrier Function in Gluten-Related Disorders

Gluten-related disorders include distinct disease entities, namely celiac disease, wheat-associated allergy and non-celiac gluten/wheat sensitivity. Despite having in common the contact of the gastrointestinal mucosa with components of wheat and other cereals as a causative factor, these clinical entities have distinct pathophysiological pathways. In celiac disease, a T-cell mediate immune reaction triggered by gluten ingestion is central in the pathogenesis of the enteropathy, while wheat allergy develops as a rapid immunoglobulin E- or non-immunoglobulin E-mediated immune response. In non-celiac wheat sensitivity, classical adaptive immune responses are not involved. Instead, recent research has revealed that an innate immune response to a yet-to-be-defined antigen, as well as the gut microbiota, are pivotal in the development in this disorder. Although impairment of the epithelial barrier has been described in all three clinical conditions, its role as a potential pathogenetic co-factor, specifically in celiac disease and non-celiac wheat sensitivity, is still a matter of investigation. This article gives a short overview of the mucosal barrier of the small intestine, summarizes the aspects of barrier dysfunction observed in all three gluten-related disorders and reviews literature data in favor of a primary involvement of the epithelial barrier in the development of celiac disease and non-celiac wheat sensitivity

Celiac Disease Monocytes Induce a Barrier Defect in Intestinal Epithelial Cells

Intestinal epithelial barrier function in celiac disease (CeD) patients is altered. However, the mechanism underlying this effect is not fully understood. The aim of the current study was to evaluate the role of monocytes in eliciting the epithelial barrier defect in CeD. For this purpose, human monocytes were isolated from peripheral blood mononuclear cells (PBMCs) from active and inactive CeD patients and healthy controls. PBMCs were sorted for expression of CD14 and co-cultured with intestinal epithelial cells (IECs, Caco2BBe). Barrier function, as well as tight junctional alterations, were determined. Monocytes were characterized by profiling of cytokines and surface marker expression. Transepithelial resistance was found to be decreased only in IECs that had been exposed to celiac monocytes. In line with this, tight junctional alterations were found by confocal laser scanning microscopy and Western blotting of ZO-1, occludin, and claudin-5. Analysis of cytokine concentrations in monocyte supernatants revealed higher expression of interleukin-6 and MCP-1 in celiac monocytes. However, surface marker expression, as analyzed by FACS analysis after immunostaining, did not reveal significant alterations in celiac monocytes. In conclusion, CeD peripheral monocytes reveal an intrinsically elevated pro-inflammatory cytokine pattern that is associated with the potential of peripheral monocytes to affect barrier function by altering TJ composition

The Use and Value of Scenario Planning

Strategies are often approached with the assumption that uncertainty can be partially understood and minimized to some extent by exploring plausible future events. Scenario planning addresses this question by using scenarios to describe more than one evolution and future state of the business environment. Throughout the years, strategists and academics have worked hard to resolve the methodological chaos (Martelli, 2001) created by the increasing number of scenario development methods. Aiming to contribute towards this goal, the history of scenario planning is covered in this paper, as well as its use and value in a range of industry sectors including energy (oil and gas), defense and space. With the insight and understanding gathered by both our research and interviews with strategists in different organizations, we propose a framework that suggests how to select different methods depending on different domain characteristics. We also use our findings to suggest how scenario planning, despite having its roots in strategic decision-making, can be a valuable input to risk management and systems design

Проблеми криптозахисту шифрувальної машинки «ЕНІГМА»

Шифрувальні пристрої дозволяють захистити інформацію, передану по радіоканалу, від перегляду сторонніми особами, і насамперед, спецслужбою супротивника. У загальному випадку букви і цифри повідомлення замінюються іншими символами, роблячи його абсолютно незрозумілим. Найпростіші шифри, що застосовувалися протягом століть, використовували схему прямого заміщення однієї букви інший, причому щоразу однієї і тієї ж

An infrastructure for experience centered agile prototyping of ambient intelligence

Ubiquitous computing poses new usability challenges that cut across design and development. We are particularly interested in "spaces" enhanced with sensors, public displays and personal devices. How can prototypes be used to explore the user's mobility and interaction, both explicitly and implicitly, to access services within these environments? Because of the potential cost of development and design failure, the characteristics of such systems must be explored using early versions of the system that could disrupt if used in the target environment. Being able to evaluate these systems early in the process is crucial to their successful development. This paper reports on an effort to develop a framework for the rapid prototyping and analysis of ambient intelligence systems

Antimicrobial resistance and class 1 integrons in Salmonella enterica subsp. enterica serovar Derby isolates from pig abattoirs

Salmonella enterica subsp. enterica (S.) serovar Derby is one of the most prevalent serovars in pigs. The aim of this study was the investigation of S. Derby isolates for the presence of antimicrobial resistance and class 1 integrons and their gene cassettes. Forty-nine S. Derby isolates, obtained from different sources at four pig abattoirs (A-D) in Southern Brazil were analysed. Five isolates were susceptible to all antimicrobial agents tested