3,335 research outputs found
Statistical mechanics of Kerr-Newman dilaton black holes and the bootstrap condition
The Bekenstein-Hawking ``entropy'' of a Kerr-Newman dilaton black hole is
computed in a perturbative expansion in the charge-to-mass ratio. The most
probable configuration for a gas of such black holes is analyzed in the
microcanonical formalism and it is argued that it does not satisfy the
equipartition principle but a bootstrap condition. It is also suggested that
the present results are further support for an interpretation of black holes as
excitations of extended objects.Comment: RevTeX, 5 pages, 2 PS figures included (requires epsf), submitted to
Phys. Rev. Let
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
Rosette‐like structures in the spectrum of spitzoid tumors
Background Spitz nevi demonstrate a diverse spectrum of morphologies. Recently, there have been two reported examples of Spitz nevi with rosette‐like structures similar to Homer‐Wright rosettes. Rosettes have also been described in melanomas and in a proliferative nodule arising in a congenital nevus. Methods A retrospective review of 104 cases of Spitz nevi and variants (n = 51), pigmented spindle cell nevi (n = 26), combined melanocytic nevi with features of Spitz (n = 8), atypical Spitz tumor ( AST , n = 9), and spitzoid melanoma (n = 10). Results Rosette‐like structures were present in 3 of the 104 cases (2.9%), including a compound Spitz nevus, a desmoplastic Spitz nevus, and an AST . All three cases demonstrated several foci of small nests of epithelioid cells with peripherally palisaded nuclei arranged around a central area of fibrillar eosinophilic cytoplasm. Immunohistochemical staining of the three spitzoid lesions demonstrated that the rosette‐like structures express S100 protein, Melan‐A, and neuron specific enolase ( NSE ) and lacked expression of neurofilament, glial fibrillary acidic protein and synaptophysin. Conclusions While uncommon, rosette‐like structures can occur as a focal feature in Spitz nevi and AST . Rosette‐like structures may represent a normal morphologic finding in Spitz nevi, and awareness of them may prevent misdiagnosis as a neural tumor or melanoma.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99651/1/cup12192.pd
Statistical Mechanics of Black Holes
We analyze the statistical mechanics of a gas of neutral and charged black
holes. The microcanonical ensemble is the only possible approach to this
system, and the equilibrium configuration is the one for which most of the
energy is carried by a single black hole. Schwarzschild black holes are found
to obey the statistical bootstrap condition. In all cases, the microcanonical
temperature is identical to the Hawking temperature of the most massive black
hole in the gas. U(1) charges in general break the bootstrap property. The
problems of black hole decay and of quantum coherence are also addressed.Comment: 21 page
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
Editorial
Denver, Theological Comments
Will the Decision on Fellowship at Denver Make a Difference?
Fellowship and the Younger Sister Churches
Synodical Conventions: A Theological Perspectiv
Malignant melanoma with osteosarcomatous differentiation in a lymph node metastasis
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145523/1/cup13283.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/145523/2/cup13283_am.pd
Microcanonical statistics of black holes and bootstrap condition
The microcanonical statistics of the Schwarzschild black holes as well as the
Reissner-Nordstrm 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
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