339 research outputs found
Computing Storyline Visualizations with Few Block Crossings
Storyline visualizations show the structure of a story, by depicting the
interactions of the characters over time. Each character is represented by an
x-monotone curve from left to right, and a meeting is represented by having the
curves of the participating characters run close together for some time. There
have been various approaches to drawing storyline visualizations in an
automated way. In order to keep the visual complexity low, rather than
minimizing pairwise crossings of curves, we count block crossings, that is,
pairs of intersecting bundles of lines.
Partly inspired by the ILP-based approach of Gronemann et al. [GD 2016] for
minimizing the number of pairwise crossings, we model the problem as a
satisfiability problem (since the straightforward ILP formulation becomes more
complicated and harder to solve). Having restricted ourselves to a decision
problem, we can apply powerful SAT solvers to find optimal drawings in
reasonable time. We compare this SAT-based approach with two exact algorithms
for block crossing minimization, using both the benchmark instances of
Gronemann et al. and random instances. We show that the SAT approach is
suitable for real-world instances and identify cases where the other algorithms
are preferable.Comment: Appears in the Proceedings of the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Energy-Momentum Localization for a Space-Time Geometry Exterior to a Black Hole in the Brane World
In general relativity one of the most fundamental issues consists in defining
a generally acceptable definition for the energy-momentum density. As a
consequence, many coordinate-dependent definitions have been presented, whereby
some of them utilize appropriate energy-momentum complexes. We investigate the
energy-momentum distribution for a metric exterior to a spherically symmetric
black hole in the brane world by applying the Landau-Lifshitz and Weinberg
prescriptions. In both the aforesaid prescriptions, the energy thus obtained
depends on the radial coordinate, the mass of the black hole and a parameter
, while all the momenta are found to be zero. It is shown that for
a special value of the parameter , the Schwarzschild space-time
geometry is recovered. Some particular and limiting cases are also discussed.Comment: 10 pages, sections 1 and 3 slightly modified, references modified and
adde
Non-equilibrium Condensation Process in a Holographic Superconductor
We study the non-equilibrium condensation process in a holographic
superconductor. When the temperature T is smaller than a critical temperature
T_c, there are two black hole solutions, the Reissner-Nordstrom-AdS black hole
and a black hole with a scalar hair. In the boundary theory, they can be
regarded as the supercooled normal phase and the superconducting phase,
respectively. We consider perturbations on supercooled Reissner-Nordstrom-AdS
black holes and study their non-linear time evolution to know about physical
phenomena associated with rapidly-cooled superconductors. We find that, for
T<T_c, the initial perturbations grow exponentially and, eventually, spacetimes
approach the hairy black holes. We also clarify how the relaxation process from
a far-from-equilibrium state proceeds in the boundary theory by observing the
time dependence of the superconducting order parameter. Finally, we study the
time evolution of event and apparent horizons and discuss their correspondence
with the entropy of the boundary theory. Our result gives a first step toward
the holographic understanding of the non-equilibrium process in
superconductors.Comment: 20 pages, 7 figure
Many body physics from a quantum information perspective
The quantum information approach to many body physics has been very
successful in giving new insight and novel numerical methods. In these lecture
notes we take a vertical view of the subject, starting from general concepts
and at each step delving into applications or consequences of a particular
topic. We first review some general quantum information concepts like
entanglement and entanglement measures, which leads us to entanglement area
laws. We then continue with one of the most famous examples of area-law abiding
states: matrix product states, and tensor product states in general. Of these,
we choose one example (classical superposition states) to introduce recent
developments on a novel quantum many body approach: quantum kinetic Ising
models. We conclude with a brief outlook of the field.Comment: Lectures from the Les Houches School on "Modern theories of
correlated electron systems". Improved version new references adde
Giant Merkel cell carcinoma of the eyelid: a case report and review of the literature
Merkel cell carcinoma (MCC) is a rare cutaneous tumor and cases located in the eyelid have been described, but still its rarity may lead to difficulty in diagnosis and delay in treatment. A 51-year-old female patient that presented with large lesions in the eyelid underwent surgery after the diagnosis of acute chalazion. Following respiratory distress secondary to pulmonary metastasis, the patient's condition deteriorated and was not fit for complete excision treatment. Histopathological investigation of the biopsies, taken from the tumor, revealed that it was undifferentiated small cell carcinoma. Our aim with this paper is to point out that more cases should be reported for more effective diagnosis, histopathological study, clinical investigation, treatment and prognosis of this specific neoplasm
Formation of bone-like apatite layer on chitosan fiber mesh scaffolds by a biomimetic spraying process
Bone-like apatite coating of polymeric substrates
by means of biomimetic process is a possible
way to enhance the bone bonding ability of the
materials. The created apatite layer is believed to have
an ability to provide a favorable environment for
osteoblasts or osteoprogenitor cells. The purpose of
this study is to obtain bone-like apatite layer onto
chitosan fiber mesh tissue engineering scaffolds, by
means of using a simple biomimetic coating process
and to determine the influence of this coating on
osteoblastic cell responses. Chitosan fiber mesh scaffolds
produced by a previously described wet spinning
methodology were initially wet with a Bioglass"–water
suspension by means of a spraying methodology and
then immersed in a simulated body fluid (SBF)
mimicking physiological conditions for one week. The
formation of apatite layer was observed morphologically
by scanning electron microscopy (SEM). As a
result of the use of the novel spraying methodology, a
fine coating could also be observed penetrating into the
pores, that is clearly within the bulk of the scaffolds.
Fourier Transform Infrared spectroscopy (FTIRATR),
Electron Dispersive Spectroscopy (EDS) and
X-ray diffraction (XRD) analysis also confirmed the
presence of apatite-like layer. A human osteoblast-like
cell line (SaOs-2) was used for the direct cell contact assays. After 2 weeks of culture, samples were observed
under the SEM. When compared to the control
samples (unmodified chitosan fiber mesh scaffolds) the
cell population was found to be higher in the Ca–P
biomimetic coated scaffolds, which indicates that the
levels of cell proliferation on this kind of scaffolds
could be enhanced. Furthermore, it was also observed
that the cells seeded in the Ca–P coated scaffolds have
a more spread and flat morphology, which reveals an
improvement on the cell adhesion patterns, phenomena
that are always important in processes such as
osteoconduction
Induction of protein catabolism in myotubes by 15(S)-hydroxyeicosatetraenoic acid through increased expression of the ubiquitin–proteasome pathway
The potential role of 15(S)-hydroxyeicosatetraenoic acid (15(S)-HETE) as an intracellular signal for increased protein catabolism and induction of the expression of key components of the ubiquitin-proteasome proteolytic pathway induced by a tumour cachectic factor, proteolysis-inducing factor has been studied in murine C2C12 myotubes. 15(S)-HETE induced protein degradation in these cells with a maximal effect at concentrations between 78 and 312 nM. The effect was attenuated by the polyunsaturated fatty acid, eicosapentaenoic acid (EPA). There was an increase in 'chymotrypsin-like' enzyme activity, the predominant proteolytic activity of the proteasome, in the same concentration range as that inducing total protein degradation, and this effect was also attenuated by EPA. 15(S)-hydroxyeicosatetraenoic acid also increased maximal expression of mRNA for proteasome subunits C2 and C5, as well as the ubiquitin-conjugating enzyme, E214k, after 4 h incubation, as determined by quantitative competitive RT-PCR. The concentrations of 15-HETE affecting gene expression were the same as those inducing protein degradation. Western blotting of cellular supernatants of myotubes treated with 15(S)-HETE for 24 h showed increased expression of p42, an ATPase subunit of the regulatory complex at similar concentrations, as well as a decrease in expression of myosin in the same concentration range. 15(S)-hydroxyeicosatetraenoic acid activated binding of nuclear factor-κB (NF-κB) in the myotube nucleus and stimulated degradation of 1-κBα. The effect on the NF-κB/1-κBα system was attenuated by EPA. In addition, the NF-κB inhibitor peptide SN50 attenuated the increased chymotrypsin-like enzyme activity in the presence of 15(S)-HETE. These results suggest that 15(S)-HETE induces degradation of myofibrillar proteins in differentiated myotubes through an induction of an increased expression of the regulatory components of the ubiquitin-proteasome proteolytic pathway possibly through the intervention of the nuclear transcription factor NF-κB, and that this process is inhibited by EPA. © 2003 Cancer Research UK
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