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

Seismic topographic scattering in the context of GW detector site selection

In this paper, we present a calculation of seismic scattering from irregular surface topography in the Born approximation. Based on US-wide topographic data, we investigate topographic scattering at specific sites to demonstrate its impact on Newtonian-noise estimation and subtraction for future gravitational-wave detectors. We find that topographic scattering at a comparatively flat site in Oregon would not pose any problems, whereas scattering at a second site in Montana leads to significant broadening of wave amplitudes in wavenumber space that would make Newtonian-noise subtraction very challenging. Therefore, it is shown that topographic scattering should be included as criterion in the site-selection process of future low-frequency gravitational-wave detectors.Comment: 16 pages, 7 figure

Non-linear dynamics near exceptional points of synthetic antiferromagnetic spin-torque oscillators

We consider a synthetic antiferromagnetic spin-torque oscillator with anisotropic interlayer exchange coupling. This system exhibits exceptional points in its linearized dynamics. We find the non-linear dynamics and the dynamical phase diagram of the system both analytically and numerically. Moreover, we show that, near one of the exceptional points, the power of the oscillator depends extremely sensitively on the injected spin current. Our findings may be useful for designing sensitive magnetometers and for other applications of spin-torque oscillators.Comment: 7 pages, 4 figure

Modelling the Northeast Atlantic circulation : implications for the spring invasion of shelf regions by Calanus finmarchicus

The appearance in spring of the copepod Calanus finmarchicus in continental shelf waters of the northeastern Atlantic has been hypothesized to be mainly attributable to invasion from across the continental slope rather than in situ overwintering. This paper describes the application of a hydrodynamic circulation model and a particle-tracking model to Northeast Atlantic waters in order to assess the influence of the flow field and ascent migration parameters on the spring invasion of C. finmarchicus. For hydrodynamic modelling, the Hamburg Shelf-Ocean Model (HAMSOM) was applied to the North Atlantic and Nordic Seas and forced with daily mean atmospheric data. Simulated flow fields from HAMSOM serve as forcing functions for a particle-tracking model of the same region. The robustness of the simulated shelf invasion in three target boxes of the Northeast Atlantic Shelf was assessed by means of a sensitivity analysis with respect to variations in four key migration parameters: overwintering depth, ascent rate, ascent timing, and depth during residence in upper layers. The invasion of the northern North Sea and Norwegian Shelf waters is more sensitive to ascent migration parameters than invasion of the Faroese Shelf. The main reason for enhanced sensitivity of the North Sea invasion is the time and space-dependent flow structure in the Faroe-Shetland Channel. Dense aggregations of overwintering C. finmarchicus are found in the Channel, but because of the complex flow field only a proportion of the overwintering stock has the capacity to reach the North Sea

Dilatonic Black Holes, Naked Singularities and Strings

We extend a previous calculation which treated Schwarschild black hole horizons as quantum mechanical objects to the case of a charged, dilaton black hole. We show that for a unique value of the dilaton parameter `a', which is determined by the condition of unitarity of the S matrix, black holes transform at the extremal limit into strings.Comment: 8 pages, REVTE

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

Erfahrungen mit "half-dose" photodynamischer Therapie mittels Verteporfin bei Chorioretinopathia centralis serosa

Zusammenfassung: Hintergrund: Chorioretinopathia centralis serosa (CCS) ist eine idiopathische, meist selbstlimitierende Erkrankung gewöhnlich jüngerer Patienten. Charakteristisches Zeichen ist eine seröse Abhebung der neurosensorischen Retina. Die Visusprognose ist gut. In bis zu 30% der Fälle kann die Erkrankung chronisch oder rezidivierend sein. Es gibt das Risiko der Entwicklung einer sekundären choroidalen Neovaskularisation. Therapeutische Optionen sind Laserphotokoagulation oder photodynamische Therapie mit Verteporfin (PDT). In den letzten Jahren ist zur Minimierung von Nebenwirkungen der PDT das Behandlungsprotokoll modifiziert worden. Diese Protokolle werden als "Half-dose-" oder "Reduce-fluence-" bzw. "Low-fluence-PDT" bezeichnet. Patienten und Methoden: Retrospektiv wurden 7Augen von 6 konsekutiven männlichen Patienten mit chronischer CCS ausgewertet. Vor "Half-dose-PDT" und am Ende des Follow-up wurden der bestkorrigierte Visus sowie die Netzhautdicke mittels "spectral-domain" optischer Kohärenztomographie bestimmt. Ergebnisse: Das Durchschnittsalter lag bei 40,7 ± 10,3Jahren. Fünf Augen erhielten 1, 1Auge 2 und 1Auge 3 "Half-dose-PDT". Das durchschnittliche Follow-up lag bei 79,8 ± 104,5Monaten. Der Visus (Snellen) war vor PDT bei 0,4 ± 0,2 und nach PDT bei 0,4 ± 0,3 (p = 0,49). Die Netzhautdicke nahm von 479μm ± 233 auf 242μm ± 60 ab (p = 0,08). Fazit: "Half-dose-PDT" ist eine sichere Behandlungsoption für Patienten mit chronischer CCS. Alle Patienten zeigten eine Abnahme der Netzhautdicke mit zum Teil vollständiger Resorption von subretinaler Flüssigkeit in 6Augen. Fünf Augen zeigten zusätzlich sowohl eine funktionelle als auch eine anatomische Verbesserung durch die Behandlun

Liposomal bupivacaine for ultrasound-guided rectus sheath blocks after midline laparotomy

Optimal pain management after open abdominal surgery is essential but can be difficult to achieve. The effects of inadequate analgesia go beyond the first few postoperative days; severe acute postoperative pain may contribute to the development of chronic postsurgical pain. Thoracic epidural analgesia is a traditional approach to the management of acute pain after open abdominal surgery but has multiple possible contraindications and can be technically challenging. In our hospital, we typically offer ultrasound-guided rectus sheath blocks with catheters when epidural analgesia is not feasible. However, the recent registration of long-acting liposomal bupivacaine in the Netherlands as well as logistical and equipment-related issues have led us to consider liposomal bupivacaine as an alternative to the use of catheters. Here, we present a short case series to describe our first clinical experiences with the use of liposomal bupivacaine in ultrasound-guided rectus sheath blocks after midline laparotomy for three patients in whom epidural insertion was contraindicated.</p

Ghost Busting: PT-Symmetric Interpretation of the Lee Model

The Lee model was introduced in the 1950s as an elementary quantum field theory in which mass, wave function, and charge renormalization could be carried out exactly. In early studies of this model it was found that there is a critical value of g^2, the square of the renormalized coupling constant, above which g_0^2, the square of the unrenormalized coupling constant, is negative. Thus, for g^2 larger than this critical value, the Hamiltonian of the Lee model becomes non-Hermitian. It was also discovered that in this non-Hermitian regime a new state appears whose norm is negative. This state is called a ghost state. It has always been assumed that in this ghost regime the Lee model is an unacceptable quantum theory because unitarity appears to be violated. However, in this regime while the Hamiltonian is not Hermitian, it does possess PT symmetry. It has recently been discovered that a non-Hermitian Hamiltonian having PT symmetry may define a quantum theory that is unitary. The proof of unitarity requires the construction of a new time-independent operator called C. In terms of C one can define a new inner product with respect to which the norms of the states in the Hilbert space are positive. Furthermore, it has been shown that time evolution in such a theory is unitary. In this paper the C operator for the Lee model in the ghost regime is constructed exactly in the V/N-theta sector. It is then shown that the ghost state has a positive norm and that the Lee model is an acceptable unitary quantum field theory for all values of g^2.Comment: 20 pages, 9 figure