Regularization of static self-forces

Various regularization methods have been used to compute the self-force acting on a static particle in a static, curved spacetime. Many of these are based on Hadamard's two-point function in three dimensions. On the other hand, the regularization method that enjoys the best justification is that of Detweiler and Whiting, which is based on a four-dimensional Green's function. We establish the connection between these methods and find that they are all equivalent, in the sense that they all lead to the same static self-force. For general static spacetimes, we compute local expansions of the Green's functions on which the various regularization methods are based. We find that these agree up to a certain high order, and conjecture that they might be equal to all orders. We show that this equivalence is exact in the case of ultrastatic spacetimes. Finally, our computations are exploited to provide regularization parameters for a static particle in a general static and spherically-symmetric spacetime.Comment: 23 pages, no figure

Conservative corrections to the innermost stable circular orbit (ISCO) of a Kerr black hole: a new gauge-invariant post-Newtonian ISCO condition, and the ISCO shift due to test-particle spin and the gravitational self-force

The innermost stable circular orbit (ISCO) delimits the transition from circular orbits to those that plunge into a black hole. In the test-mass limit, well-defined ISCO conditions exist for the Kerr and Schwarzschild spacetimes. In the finite-mass case, there are a large variety of ways to define an ISCO in a post-Newtonian (PN) context. Here I generalize the gauge-invariant ISCO condition of Blanchet & Iyer (2003) to the case of spinning (nonprecessing) binaries. The Blanchet-Iyer ISCO condition has two desirable and unexpected properties: (1) it exactly reproduces the Schwarzschild ISCO in the test-mass limit, and (2) it accurately approximates the recently-calculated shift in the Schwarzschild ISCO frequency due to the conservative-piece of the gravitational self-force [Barack & Sago (2009)]. The generalization of this ISCO condition to spinning binaries has the property that it also exactly reproduces the Kerr ISCO in the test-mass limit (up to the order at which PN spin corrections are currently known). The shift in the ISCO due to the spin of the test-particle is also calculated. Remarkably, the gauge-invariant PN ISCO condition exactly reproduces the ISCO shift predicted by the Papapetrou equations for a fully-relativistic spinning particle. It is surprising that an analysis of the stability of the standard PN equations of motion is able (without any form of "resummation") to accurately describe strong-field effects of the Kerr spacetime. The ISCO frequency shift due to the conservative self-force in Kerr is also calculated from this new ISCO condition, as well as from the effective-one-body Hamiltonian of Barausse & Buonanno (2010). These results serve as a useful point-of-comparison for future gravitational self-force calculations in the Kerr spacetime.Comment: 17 pages, 2 figures, 1 table. v2: references added; minor changes to match published versio

The combustion behavior of epoxy‐based multifunctional electrolytes

Multifunctional or structural electrolytes are characterized by ionic conductivity high enough to be used in the electrochemical devices and mechanical performance suitable for the structural applications. Preliminary insights are provided into the combustion behavior of structural bi‐continuous electrolytes based on bisphenol A diglycidyl ether (DGEBA), synthesized using the techniques of reaction induced phase separation and emulsion templating. The effect of the composition of the structural electrolytes and external heat flux on the behavior of the formulations were studied using a cone calorimeter with gases formed during testing analyzed using FTIR. The composition of the formulations investigated was changed by varying the type and amount of the ion conductive part of the bi‐continuous electrolyte. Two ionic liquids, 1‐ethyl‐3‐methylimidazolium bis(fluorosulfonyl)imide (EMIM‐TFSI) and 1‐butyl‐3‐methylimidazolium tetrafluoroborate (BMIM‐BF4), as well as a deep eutectic solvent (DES) based on ethylene glycol and choline chloride, were used. The results obtained confirm that time to ignition, heat release rate (HRR), total mass loss, as well as the composition of the gases released during tests depend on the composition of the formulations. Addition of liquid electrolyte is found to reduce the time to ignition by up to 10% and the burning time by between 28% and 60% with the added benefit of reducing the HRR by at least 34%. Gaseous products such as CO2, CO, H2O, CH4, C2H2, N2O, NO, and HCN were detected for all formulations with the gases SO2, NH3, HCl, C2H4, and NH3 found to be for certain formulations only

Thin-shell wormholes in Einstein-Maxwell theory with a Gauss-Bonnet term

We study five dimensional thin-shell wormholes in Einstein-Maxwell theory with a Gauss-Bonnet term. The linearized stability under radial perturbations and the amount of exotic matter are analyzed as a function of the parameters of the model. We find that the inclusion of the quadratic correction substantially widens the range of possible stable configurations, and besides it allows for a reduction of the exotic matter required to construct the wormholes.Comment: 13 pages, 6 figures; v2: minor changes and new references added. Accepted for publication in General Relativity and Gravitatio

MARUCA PENICHET, MISS GRAN CANARIA. [Material gráfico]

** DE PLACA ORIGINAL ADQUIRIDA POR EL COLECCIONISTA EN LAS PALMAS DE GRAN CANARIAFOTO DE RETRATO DE SEÑORITA CON MANTILLA VISTA DESDE CINTURA. MISS GRAN CANARIA. MARUCA PENICHETCopia digital. Madrid : Ministerio de Educación, Cultura y Deporte. Subdirección General de Coordinación Bibliotecaria, 201

Quantization of fermions on Kerr space-time

We study a quantum fermion field on a background nonextremal Kerr black hole. We discuss the definition of the standard black hole quantum states (Boulware, Unruh, and Hartle-Hawking), focussing particularly on the differences between fermionic and bosonic quantum field theory. Since all fermion modes (both particle and antiparticle) have positive norm, there is much greater flexibility in how quantum states are defined compared with the bosonic case. In particular, we are able to define a candidate Boulware-like state, empty at both past and future null infinity, and a candidate Hartle-Hawking-like equilibrium state, representing a thermal bath of fermions surrounding the black hole. Neither of these states have analogues for bosons on a nonextremal Kerr black hole and both have physically attractive regularity properties. We also define a number of other quantum states, numerically compute differences in expectation values of the fermion current and stress-energy tensor between two states, and discuss their physical properties

Pleistocene eruptive chronology of the Gölcük volcano, Isparta Angle, Turkey. Chronologie des épisodes volcaniques pléistocènes du volcan Gölcük, Angle d’Isparta, Turquie

In the Eastern Mediterranean region, the Isparta volcanic belongs to the post-collisional alkali-potassic to ultrapotassic magmatism active since the Miocene in this part of the Anatolian peninsula from Afyon to Isparta. In the so-called Isparta Angle (IA) the magmatism is contemporaneous with an extensional regime intiated during Late Miocene and active throughout the Pliocene and Quaternary. Previous K/Ar dating performed on lavas suggested that potassic-ultrapotassic magmatism occurred between 4.7 to 4 Ma. However, a more recent (Quaternary) activity of the Gölcük volcano is evidenced by the present-day morphology and field evidence although it remained undated and poorly studied so far. Field mapping and new radiometric data indicate that the main volcano-forming stages of the Gölcük volcano consist of three main eruptives cycles. (1) Cycle I, represented by more than 200m-thick pyroclastic flow deposits occasionally separated by paleosoils and corresponding to caldera-forming ignimbritic eruptions. (2) Cycle II, consisting of tephriphonolite lava dome-flows extruded throughout the caldera and currently found along the rim of the present crater. (3) Cycle III made up of tuff-ring deposits related to several phreatoplinian eruptions of a maar-type volcanic activity. This youngest cycle ends with trachytic domes protruding within the maar crater. Unspiked 40K/40Ar dating on mesostasis was performed on lavas (tephriphonolites and trachytic domes), and complemented by preliminary 40Ar/39Ar data on tephra deposits (sanidine). Our preliminary results show that the entire activity of Gölcük volcano took place during the Pleistocene and was disconnected from the older Pliocene volcanism. This volcanic activity can be considered as a new volcanic cycle, starting (Cycle I) around 200 ka with major explosive, regional-scale, events represented by at least six ignimbrites sheets. Cycle II occurred between 115 ± 3 ka to 62 ± 2 ka with probably some associated tephra deposits. Tuff-ring of Cycle III formed from 72.7 ± 4.7 ka to 24 ± 2 ka. The associated phreatoplinian eruptions have almost entirely destroyed the previously formed flow-dome. This latest activity corresponds to several volcanic crises as illustrated by the two domes protrusions separated by about 30 ka. The volcanic history of Gölcük ceased around 24 ka ± 2 ka, but the periodicity of eruptive events appears to be long and complex. Currently, the volcano is at rest, but there is no doubt that the Isparta town (more than 120 000 people) built on top of the most recent tephra falls is exposed to a major volcanic hazard in the future.En Méditerranée Orientale, la région active d’Isparta est le siège d’un magmatisme alcalin lié à la distension affectant cette partie de la Péninsule Anatolienne depuis le Miocène supérieur. Le volcanisme Pliocène est alcalin et très potassique, depuis des magmas lamprophyriques à lamproïtiques, jusqu’à des téphriphonolites et des trachytes. La construction du volcan Gölcük au sud d’Isparta marque le début d’un nouveau cycle éruptif après une longue période d’arrêt et d’érosion. L’étude morpho-structurale du volcan couplée aux datations 40K/40Ar sur lave et 39Ar/40Ar sur monograin de feldspath-K indique une histoire éruptive complexe, nettement plus jeune que l’activité antérieure (Pliocène). Ces résultats préliminaires montrent que l’activité volcanique du Gölcük est située dans le Pléistocène supérieur (Paléolithique) entre environ 200 ka et 24 ka. Trois cycles volcaniques majeurs sont reconnus : (1) Cycle I débutant vers 200 ka avec des éruptions ignimbritiques majeures avec un ensemble de coulées pyroclastiques trachytiques comblant les paléo-vallées ouvertes dans les formations sédimentaires et les formations volcaniques d’âge pliocène ; (2) Cycle II avec un épisode effusif de faible importance succède entre 115 ± 3 ka et 62 ± 2 ka à l’activité explosive initiale avec la mise en place d’un édifice central constitué de dômes-coulées téphri-phonolitiques ; (3) Cycle III entre 70 ka et 24 ka, l’activité devient phréatoplinienne et suit de près le cycle précédent. Le dynamisme éruptif phréatomagmatique est celui d’un maar formé d’un large cratère d’explosion entouré d’un anneau de tufs. La dernière crise volcanique se termine par l’extrusion de plusieurs dômes de trachyte dans le cratère et de téphras associés, de nouvelles coulées pyroclastiques se mettent vraisemblablement en place vers le nord-ouest. Les données de terrain et les âges 40Ar/39Ar disponibles indiquent que ces dernières manifestations (construction du maar) sont très récentes et sub-contemporaines du dernier niveau de retombées ponceuses sous les immeubles de la ville et des dômes de lave intra-caldeira. Cet âge récent est confirmé par un âge 14C obtenu sur des bois carbonisés. La morphologie du volcan actuel est relativement bien conservée, malgré l’érosion très active qui remodèle déjà partiellement les pentes. La reprise éventuelle de l’activité du volcan constituerait un risque majeur à l’échelle de la région et en particulier pour la ville d’Isparta établie au pied de l’édifice, notamment sur les coulées pyroclastiques et les retombées ponceuses les plus récentes

Offspring mass variation in tree swallows : a case of bet‐hedging?

The evolution of reproductive strategies is affected by the ability of organisms to deal with future environmental conditions. When environments are temporally unpredictable, however, it is difficult to anticipate optimal offspring phenotype. Diversification of offspring phenotypes, a strategy called diversified bet‐hedging, may allow parents to maximize their fitness by reducing between‐year variation in reproductive success. The link between diversification of offspring phenotypes and individual reproductive success, however, has rarely been documented empirically. We used an eight‐year dataset (1215 broods, 870 females) on individually marked tree swallows ( Tachycineta bicolor ) to assess whether intra‐brood mass variation was compatible with a diversified bet‐hedging strategy. Intra‐brood mass variation was weakly, but significantly repeatable within females, suggesting consistent individual differences. Greater intra‐brood mass variation, however, was not associated with reduced between‐year variation in reproductive success or increased female reproductive success. Moreover, contrary to diversified bet‐hedging expectations, fledging success of large broods was greater when hatchlings had similar rather than variable masses. Our results suggest that intra‐brood mass variation may not result from diversified bet‐hedging, but rather from complex interactions between environmental, brood, and maternal characteristics

Blockade of IL-33R/ST2 Signaling Attenuates Toxoplasma gondii Ileitis Depending on IL-22 Expression

Oral T. gondii infection (30 cysts of 76K strain) induces acute lethal ileitis in sensitive C57BL/6 (B6) mice with increased expression of IL-33 and its receptor ST2 in the ileum. Here we show that IL-33 is involved in ileitis, since absence of IL-33R/ST2 attenuated neutrophilic inflammation and Th1 cytokines upon T. gondii infection with enhanced survival. Blockade of ST2 by neutralizing ST2 antibody in B6 mice conferred partial protection, while rmIL-33 aggravated ileitis. Since IL-22 expression further increased in absence of ST2, we blocked IL-22 by neutralizing antibody, which abrogated protection from acute ileitis in ST2 deficient mice. In conclusion, severe lethal ileitis induced by oral T. gondii infection is attenuated by blockade of ST2 signaling and may be mediated in part by endogenous IL-22

Intermediate and extreme mass-ratio inspirals — astrophysics, science applications and detection using LISA

Black hole binaries with extreme (gtrsim104:1) or intermediate (~102–104:1) mass ratios are among the most interesting gravitational wave sources that are expected to be detected by the proposed laser interferometer space antenna (LISA). These sources have the potential to tell us much about astrophysics, but are also of unique importance for testing aspects of the general theory of relativity in the strong field regime. Here we discuss these sources from the perspectives of astrophysics, data analysis and applications to testing general relativity, providing both a description of the current state of knowledge and an outline of some of the outstanding questions that still need to be addressed. This review grew out of discussions at a workshop in September 2006 hosted by the Albert Einstein Institute in Golm, Germany