Perturbations in the Kerr-Newman Dilatonic Black Hole Background: I. Maxwell waves

In this paper we analyze the perturbations of the Kerr-Newman dilatonic black hole background. For this purpose we perform a double expansion in both the background electric charge and the wave parameters of the relevant quantities in the Newman-Penrose formalism. We then display the gravitational, dilatonic and electromagnetic equations, which reproduce the static solution (at zero order in the wave parameter) and the corresponding wave equations in the Kerr background (at first order in the wave parameter and zero order in the electric charge). At higher orders in the electric charge one encounters corrections to the propagations of waves induced by the presence of a non-vanishing dilaton. An explicit computation is carried out for the electromagnetic waves up to the asymptotic form of the Maxwell field perturbations produced by the interaction with dilatonic waves. A simple physical model is proposed which could make these perturbations relevant to the detection of radiation coming from the region of space near a black hole.Comment: RevTeX, 36 pages in preprint style, 1 figure posted as a separate PS file, submitted to Phys. Rev.

Microfield Dynamics of Black Holes

The microcanonical treatment of black holes as opposed to the canonical formulation is reviewed and some major differences are displayed. In particular the decay rates are compared in the two different pictures.Comment: 22 pages, 4 figures, Revtex, Minor change in forma

Perturbations in the Kerr-Newman Dilatonic Black Hole Background: Maxwell Waves, the Dilaton Background and Gravitational Lensing

In this paper we continue the analysis of our previous papers and study the affect of the existence of a non-trivial dilaton background on the propagation of electromagnetic waves in the Kerr-Newman dilatonic black hole space-time. For this purpose we again employ the double expansion in both the background electric charge and the wave parameters of the relevant quantities in the Newman-Penrose formalism and then identify the first order at which the dilaton background enters the Maxwell equations. We then assume that gravitational and dilatonic waves are negligible (at that order in the charge parameter) with respect to electromagnetic waves and argue that this condition is consistent with the solutions already found in the previous paper. Explicit expressions are given for the asymptotic behavior of scattered waves, and a simple physical model is proposed in order to test the effects. An expression for the relative intensity is obtained for Reissner-Nordstrom dilaton black holes using geometrical optics. A comparison with the approximation of geometrical optics for Kerr-Newman dilaton black holes shows that at the order to which the calculations are carried out gravitational lensing of optical images cannot probe the dilaton background.Comment: 9 pages, 1 figur

On dispersion relations and the statistical mechanics of Hawking radiation

We analyze the interplay between dispersion relations for the spectrum of Hawking quanta and the statistical mechanics of such a radiation. We first find the general relation between the occupation number density and the energy spectrum of Hawking quanta and then study several cases in details. We show that both the canonical and the microcanonical picture of the evaporation lead to the same linear dispersion relation for relatively large black holes. We also compute the occupation number obtained by instead assuming that the spectrum levels out (and eventually falls to zero) for very large momenta and show that the luminosity of black holes is not appreciably affected by the modified statistics.Comment: LaTeX, 12 pages, 6 eps figures included, final version to appear in Class. Quantum Gravit

Alkali- Metal Corrosion of Refractory Metals

This report talks about the Alkali- Metal Corrosion of Refractory Metal

Mandibular Actinomyces osteomyelitis complicating florid cemento-osseous dysplasia: case report

Abstract Background Apart from neoplastic processes, chronic disfiguring and destructive diseases of the mandible are uncommon. Case Presentation We report, perhaps for the first time, the simultaneous occurrence of two such conditions in one patient, in a case that emphasizes the importance of bone biopsy in establishing the correct diagnosis. Florid cemento-osseous dysplasia (FCOD) is a chronic, disfiguring condition of the maxillofacial region. This relatively benign disease is primarily observed in middle-aged women of African ancestry. Cervicofacial actinomycosis is an uncommon and progressive infection caused by bacilli of the Actinomyces genus that typically involves intraoral soft tissues but may also involve bone. The accurate diagnosis of actinomycosis is critical for successful treatment. A diagnosis of osteomyelitis caused by Actinomyces bacteria was diagnosed by bone biopsy in a 53 year-old African-American woman with a longstanding history of FCOD after she presented with a new draining ulcer overlying the mandible. Conclusions Clinicians should be aware of the possibility of actinomycosis arising in the setting of FCOD, and the importance of bone biopsy and cultures in arriving at a definitive and timely diagnosis.http://deepblue.lib.umich.edu/bitstream/2027.42/112686/1/12903_2011_Article_189.pd

Squeezed Light for the Interferometric Detection of High Frequency Gravitational Waves

The quantum noise of the light field is a fundamental noise source in interferometric gravitational wave detectors. Injected squeezed light is capable of reducing the quantum noise contribution to the detector noise floor to values that surpass the so-called Standard-Quantum-Limit (SQL). In particular, squeezed light is useful for the detection of gravitational waves at high frequencies where interferometers are typically shot-noise limited, although the SQL might not be beaten in this case. We theoretically analyze the quantum noise of the signal-recycled laser interferometric gravitational-wave detector GEO600 with additional input and output optics, namely frequency-dependent squeezing of the vacuum state of light entering the dark port and frequency-dependent homodyne detection. We focus on the frequency range between 1 kHz and 10 kHz, where, although signal recycled, the detector is still shot-noise limited. It is found that the GEO600 detector with present design parameters will benefit from frequency dependent squeezed light. Assuming a squeezing strength of -6 dB in quantum noise variance, the interferometer will become thermal noise limited up to 4 kHz without further reduction of bandwidth. At higher frequencies the linear noise spectral density of GEO600 will still be dominated by shot-noise and improved by a factor of 10^{6dB/20dB}~2 according to the squeezing strength assumed. The interferometer might reach a strain sensitivity of 6x10^{-23} above 1 kHz (tunable) with a bandwidth of around 350 Hz. We propose a scheme to implement the desired frequency dependent squeezing by introducing an additional optical component to GEO600s signal-recycling cavity.Comment: Presentation at AMALDI Conference 2003 in Pis

Optical and Electrical Measurements Reveal the Orientation Mechanism of Homoleptic Iridium-Carbene Complexes

Understanding and controlling the driving forces for molecular alignment in optoelectronic thin-film devices is of crucial importance for improving their performance. In this context, the preferential orientation of organometallic iridium complexes is in the focus of research to benefit from their improved light-outcoupling efficiencies in organic light-emitting diodes (OLEDs). Although there has been great progress concerning the orientation behavior for heteroleptic Ir complexes, the mechanism behind the alignment of homoleptic complexes is still unclear yet. In this work, we present a sky-blue phosphorescent dye that shows variable alignment depending on systematic modifications of the ligands bound to the central iridium atom. From an optical study of the transition dipole moment orientation and the electrically accessible alignment of the permanent dipole moment, we conclude that the film morphology is related to both the aspect ratio of the dye and the local electrostatic interaction of the ligands with the film surface during growth. These results indicate a potential strategy to actively control the orientation of iridium-based emitters for the application in OLEDs

Microcanonical statistics of black holes and bootstrap condition

The microcanonical statistics of the Schwarzschild black holes as well as the Reissner-Nordstr$\sf \ddot{o}$m black holes are analyzed. In both cases we set up the inequalities in the microcanonical density of states. These are then used to show that the most probable configuration in the gases of black holes is that one black hole acquires all of the mass and all of the charge at high energy limit. Thus the black holes obey the statistical bootstrap condition and, in contrast to the other investigation, we see that U(1) charge does not break the bootstrap property.Comment: 16 pages. late

Follow-up observations of pulsating subdwarf B stars: Multisite campaigns on PG 1618+563B and PG 0048+091

We present follow-up observations of pulsating subdwarf B (sdB) stars as part of our efforts to resolve the pulsation spectra for use in asteroseismological analyses. This paper reports on multisite campaigns of the pulsating sdB stars PG 1618+563B and PG 0048+091. Data were obtained from observatories placed around the globe for coverage from all longitudes. For PG 1618+563B, our five-site campaign uncovered a dichotomy of pulsation states: Early during the campaign the amplitudes and phases (and perhaps frequencies) were quite variable while data obtained late in the campaign were able to fully resolve five stable pulsation frequencies. For PG 0048+091, our five-site campaign uncovered a plethora of frequencies with short pulsation lifetimes. We find them to have observed properties consistent with stochastically excited oscillations, an unexpected result for subdwarf B stars. We discuss our findings and their impact on subdwarf B asteroseismology.Comment: 50 pages including 17 figures and 10 tables. Accepted for publication in the Astrophysical Journa