837 research outputs found
A combined wavelet-element free Galerkin method for numerical calculations of electromagnetic fields
Author name used in this publication: S. L. HoAuthor name used in this publication: J. M. Machado2002-2003 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
An improved tabu-based vector optimal algorithm for design optimizations of electromagnetic devices
Author name used in this publication: S. Y. YangAuthor name used in this publication: S. L. HoAuthor name used in this publication: J. M. MachadoAuthor name used in this publication: Edward W. C. Lo2003-2004 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Nernst branes from special geometry
We construct new black brane solutions in gauged
supergravity with a general cubic prepotential, which have entropy density
as and thus satisfy the Nernst Law. By using
the real formulation of special geometry, we are able to obtain analytical
solutions in closed form as functions of two parameters, the temperature
and the chemical potential . Our solutions interpolate between
hyperscaling violating Lifshitz geometries with at the
horizon and at infinity. In the zero temperature limit,
where the entropy density goes to zero, we recover the extremal Nernst branes
of Barisch et al, and the parameters of the near horizon geometry change to
.Comment: 37 pages. v2: numerical pre-factors of scalar fields q_A corrected in
Section 3. No changes to conclusions. References adde
Observation of coherent hybrid reflection with synchrotron radiation
High resolution synchrotron radiation has been used to investigate the occurrence of coherent hybrid reflections (CHR) in the In0.49Ga0.51P/GaAs(001) structure. Several phi scans at the 002 layer reflection were carried out. The scanned phi intervals are correlated by the axis symmetry and [001] should present the same pattern. A break in the symmetry is observed due to constructive/destructive interference of the hybrid amplitudes with the amplitude from the 002 layer reflection. The effects of substrate miscut and interface distance are taken into account to explain the observed patterns. The application of CHR as a high sensitive tool to analyze epitaxial growth is discussed. (C) 1998 American Institute of Physics. [S0003-6951(98)03841-8].73152194219
Nernst branes in gauged supergravity
We study static black brane solutions in the context of N = 2 U(1) gauged
supergravity in four dimensions. Using the formalism of first-order flow
equations, we construct novel extremal black brane solutions including examples
of Nernst branes, i.e. extremal black brane solutions with vanishing entropy
density. We also discuss a class of non-extremal generalizations which is
captured by the first-order formalism.Comment: 44 pages, 3 figures, v2: added appendix B and references, minor
typographic changes, v3: added some clarifying remarks, version published in
JHE
Stability study of a model for the Klein-Gordon equation in Kerr spacetime
The current early stage in the investigation of the stability of the Kerr
metric is characterized by the study of appropriate model problems.
Particularly interesting is the problem of the stability of the solutions of
the Klein-Gordon equation, describing the propagation of a scalar field of mass
in the background of a rotating black hole. Rigorous results proof the
stability of the reduced, by separation in the azimuth angle in Boyer-Lindquist
coordinates, field for sufficiently large masses. Some, but not all, numerical
investigations find instability of the reduced field for rotational parameters
extremely close to 1. Among others, the paper derives a model problem for
the equation which supports the instability of the field down to .Comment: Updated version, after minor change
Slicing and Allocation of Transformable Resources for the Deployment of Multiple Virtualized Infrastructure Managers (VIMs)
In the context of 5G networks, the concept of network slicing allows network providers to flexibly share infrastructures with mobile service providers and verticals. While this concept has been widely investigated considering mostly the network issues, in this work we focus on a slice as a service model that takes into account the data center (DC) perspective. In particular, we propose an architecture where DC slices are created over transformable (compute and storage) resources, which can be virtualized or de-virtualized on-demand. Then, on top of each slice, an on-demand VIM is instantiated to control the allocated resources. As a realization of this architecture, we introduce the DC Slice Controller, a system able to deploy and delivery full operational VIMs based on generic templates. We evaluate the effectiveness of the proposed system deploying three VIMs (VLSP, Kubernetes, and OpenStack) over commodity hardware. Experimental results show that the DC Slice Controller can timely provide a slice even when dealing with sophisticated VIMs such as OpenStack. As an example, we were able to delivery a fully functional OpenStack in four nodes in less than 10 minutes
Evaluation of matrix metalloproteinases-2 and-9 in cats under bone demineralization secondary to induced thyrotoxicosis
Significant increase of activity of active forms of matrix metalloproteinases -2 and -9 in cats under induced thyrotoxicosis and bone demineralization was observed. Pro and intermediated forms of matrix metalloproteinases -2 and -9 increased at 14 days of hormonal treatment, followed by decrease tendency. A negative correlation between active forms of matrix metalloproteinases -2 and -9 and bone mineral density of radius distal extremity was also observed. The results suggest an increase of collagen matrix degradation secondary to high levels of thyroid hormones.6051053106
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
Medication-related osteonecrosis of the jaw. Introduction of a new modified experimental model
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