On BPS bounds in D=4 N=2 gauged supergravity II: general matter couplings and black hole masses

We continue the analysis of BPS bounds started in arXiv:1110.2688, extending it to the full class of N=2 gauged supergravity theories with arbitrary vector and hypermultiplets. We derive the general form of the asymptotic charges for asymptotically flat (M_4), anti-de Sitter (AdS_4), and magnetic anti-de Sitter (mAdS_4) spacetimes. Some particular examples from black hole physics are given to explicitly demonstrate how AdS and mAdS masses differ when solutions with non-trivial scalar profiles are considered.Comment: 21 pages; v2 added reference, published version; v3 minor correction

Changes of some biophysical values in animals under moderate stress

In recent years, in the medical world the number of studies related to certain biophysical characteristics of biologically active points (similar to acupuncture points) - BAP, antenna and electromagnetic radiation effect of the body is increasing. As a product of nature, organisms come into simpler or more complex relationship with the various forms of manifestation of natural energy and particularly the electromagnetic one. Aim of this study was to identify changes in the antenna effect, electromagnetic radiation and resistance and semiconductor effect in BAP of experimental animals under oxidative stress response to hypobaric hypoxia and hyperbaric hyperoxia, cold and heat shock, physical exertion and prolonged immobilization. The general impression from the results obtained from different models of stress conditions, is that changes in biophysical parameters studied, with few exceptions in parameters and in varying degrees of variability are one-way and statistically significant The increasing of antenna effect and electromagnetic radiation from one side and reducing resistance and of semiconductor effect in acupuncture point Yin-Tang considered for "basic energizer of the organism" at the other, in wide physical aspect are proof for an increase of communicative opportunities of animals under different stress opportunities. To build on the findings of experimental study it is necessary to extend the number of animals in the respective groups, and conduct further experiments with other stressful conditions. Scripta Scientifica Medica 2011;43(2): 97-10

Nonperturbative resonant strong field ionization of atomic hydrogen

We investigate resonant strong field ionization of atomic hydrogen with respect to the 1s-2p-transition. By "strong" we understand that Rabi-periods are executed on a femtosecond time scale. Ionization and AC Stark shifts modify the bound state dynamics severely, leading to nonperturbative signatures in the photoelectron spectra. We introduce an analytical model, capable of predicting qualitative features in the photoelectron spectra such as the positions of the Autler-Townes peaks for modest field strengths. Ab initio solutions of the time-dependent Schroedinger equation show a pronounced shift and broadening of the left Autler-Townes peak as the field strength is increased. The right peak remains rather narrow and shifts less. This result is analyzed and explained with the help of exact AC Stark shifts and ionization rates obtained from Floquet theory. Finally, it is demonstrated that in the case of finite pulses as short as 20fs the Autler-Townes duplet can still be resolved. The fourth generation light sources under construction worldwide will provide bright, coherent radiation with photon energies ranging from a tenth of a meV up to tens of keV, hence covering the regime studied in the paper so that measurements of nonperturbative, relative AC Stark shifts should become feasible with these new light sources.Comment: 16 pages, 11 figures, IOP styl

A study of nucleate boiling and critical heat flux with EHD enhancement

The paper describes results from an experimental and theoretical study of the effect of an electric field on nucleate boiling and the critical heat flux (CHF) in pool boiling of R123 at atmospheric pressure on a horizontal wall with a smooth surface. Two designs of electrode (parallel rods and wire mesh) were used. The experimental data exhibit some differences from the data obtained by other researchers in similar experiments on a wall with a different surface finish and with a slightly different design of wire mesh electrode. The hydrodynamic model for EHD enhancement of CHF cannot reconcile the differences. A theoretical model has been developed for the growth of a single vapour bubble on a superheated wall in an electric field, leading to a numerical simulation based on the level-set method. The model includes matching of sub-models for the micro- and macro- regions, conduction in the wall, distortion of the electric field by the bubble, the temperature dependence of electrical properties and free-charge generation. In the present form of the model, some of these effects are realised in an approximate form. The capability to investigate dry-spot formation and wall temperature changes that might lead to CHF has been demonstrated

Modelling of the growth and detachment of a vapour bubble and the effect of a electric field in the nucleate boiling regime

A comprehensive model predicting the deformation, growth and detachment of a vapour bubble in the nucleate boiling regime with an applied electric field is described in this paper. The model takes into account the full electrohydrodynamics of the phenomenon including the influence of local temperature on the generation of free charges in the liquid. Solution of the model by the level set method has been successfully implemented with a commercial CFD code. Aspects of the code and the graphical software requiring further development are noted. Sample results are presented to demonstrate the effect of the electric field on the growth and detachment of the bubble, for a bubble initially protruding through a thermal boundary layer on a horizontal wall. The bubble is elongated under the influence of electrical forces, the effect being more pronounced for stronger electrical fields. The electric field is found to promote earlier detachment of the bubble at a smaller volume, thus increasing the bubble frequency. The wall heat flux during the process of detachment is not much affected by the electric field

The Herschel-SPIRE instrument and its in-flight performance

The Spectral and Photometric Imaging REceiver (SPIRE), is the Herschel Space Observatory`s submillimetre camera and spectrometer. It contains a three-band imaging photometer operating at 250, 350 and 500 μm, and an imaging Fourier-transform spectrometer (FTS) which covers simultaneously its whole operating range of 194–671 μm (447–1550 GHz). The SPIRE detectors are arrays of feedhorn-coupled bolometers cooled to 0.3 K. The photometer has a field of view of 4´× 8´, observed simultaneously in the three spectral bands. Its main operating mode is scan-mapping, whereby the field of view is scanned across the sky to achieve full spatial sampling and to cover large areas if desired. The spectrometer has an approximately circular field of view with a diameter of 2.6´. The spectral resolution can be adjusted between 1.2 and 25 GHz by changing the stroke length of the FTS scan mirror. Its main operating mode involves a fixed telescope pointing with multiple scans of the FTS mirror to acquire spectral data. For extended source measurements, multiple position offsets are implemented by means of an internal beam steering mirror to achieve the desired spatial sampling and by rastering of the telescope pointing to map areas larger than the field of view. The SPIRE instrument consists of a cold focal plane unit located inside the Herschel cryostat and warm electronics units, located on the spacecraft Service Module, for instrument control and data handling. Science data are transmitted to Earth with no on-board data compression, and processed by automatic pipelines to produce calibrated science products. The in-flight performance of the instrument matches or exceeds predictions based on pre-launch testing and modelling: the photometer sensitivity is comparable to or slightly better than estimated pre-launch, and the spectrometer sensitivity is also better by a factor of 1.5–2

Observations of the Near-infrared Spectrum of the Zodiacal Light with CIBER

Interplanetary dust (IPD) scatters solar radiation which results in the zodiacal light that dominates the celestial diffuse brightness at optical and near-infrared wavelengths. Both asteroid collisions and cometary ejections produce the IPD, but the relative contribution from these two sources is still unknown. The low resolution spectrometer (LRS) onboard the Cosmic Infrared Background ExpeRiment (CIBER) observed the astrophysical sky spectrum between 0.75 and 2.1 μm over a wide range of ecliptic latitude. The resulting zodiacal light spectrum is redder than the solar spectrum, and shows a broad absorption feature, previously unreported, at approximately 0.9 μm, suggesting the existence of silicates in the IPD material. The spectral shape of the zodiacal light is isotropic at all ecliptic latitudes within the measurement error. The zodiacal light spectrum, including the extended wavelength range to 2.5 μm using Infrared Telescope in Space (IRTS) data, is qualitatively similar to the reflectance of S-type asteroids. This result can be explained by the proximity of S-type asteroidal dust to Earth's orbit, and the relatively high albedo of asteroidal dust compared with cometary dust

Rotating BPS black holes in matter-coupled AdS(4) supergravity

Using the general recipe given in arXiv:0804.0009, where all timelike supersymmetric solutions of N=2, D=4 gauged supergravity coupled to abelian vector multiplets were classified, we construct genuine rotating supersymmetric black holes in AdS(4) with nonconstant scalar fields. This is done for the SU(1,1)/U(1) model with prepotential F=-iX^0X^1. In the static case, the black holes are uplifted to eleven dimensions, and generalize the solution found in hep-th/0105250 corresponding to membranes wrapping holomorphic curves in a Calabi-Yau five-fold. The constructed rotating black holes preserve one quarter of the supersymmetry, whereas their near-horizon geometry is one half BPS. Moreover, for constant scalars, we generalize (a supersymmetric subclass of) the Plebanski-Demianski solution of cosmological Einstein-Maxwell theory to an arbitrary number of vector multiplets. Remarkably, the latter turns out to be related to the dimensionally reduced gravitational Chern-Simons action.Comment: 23 pages, uses JHEP3.cl

BPS black holes in N=2 D=4 gauged supergravities

We construct and analyze BPS black hole solutions in gauged N=2, D=4 supergravity with charged hypermultiplets. A class of solutions can be found through spontaneous symmetry breaking in vacua that preserve maximal supersymmetry. The resulting black holes do not carry any hair for the scalars. We demonstrate this with explicit examples of both asymptotically flat and anti-de Sitter black holes. Next, we analyze the BPS conditions for asymptotically flat black holes with scalar hair and spherical or axial symmetry. We find solutions only in cases when the metric contains ripples and the vector multiplet scalars become ghost-like. We give explicit examples that can be analyzed numerically. Finally, we comment on a way to circumvent the ghost-problem by introducing also fermionic hair.Comment: 40 pages, 2 figures; v2 references added; v3 minor changes, published versio

Approximate Solutions to Fractional Subdiffusion Equations: The heat-balance integral method

The work presents integral solutions of the fractional subdiffusion equation by an integral method, as an alternative approach to the solutions employing hypergeometric functions. The integral solution suggests a preliminary defined profile with unknown coefficients and the concept of penetration (boundary layer). The prescribed profile satisfies the boundary conditions imposed by the boundary layer that allows its coefficients to be expressed through its depth as unique parameter. The integral approach to the fractional subdiffusion equation suggests a replacement of the real distribution function by the approximate profile. The solution was performed with Riemann -Liouville time-fractional derivative since the integral approach avoids the definition of the initial value of the time-derivative required by the Laplace transformed equations and leading to a transition to Caputo derivatives. The method is demonstrated by solutions to two simple fractional subdiffusion equations (Dirichlet problems): 1) Time-Fractional Diffusion Equation, and 2) Time-Fractional Drift Equation, both of them having fundamental solutions expressed through the M-Write function. The solutions demonstrate some basic issues of the suggested integral approach, among them: a) Choice of the profile, b) Integration problem emerging when the distribution (profile) is replaced by a prescribed one with unknown coefficients; c) Optimization of the profile in view to minimize the average error of approximations; d) Numerical results allowing comparisons to the known solutions expressed to the M-Write function and error estimations.Comment: 15 pages, 7 figures, 3 table