1,781 research outputs found
Effects of Uniaxial Cyclic Strain on Endothelial Progenitor Cells
Despite the high prevalence of calcific aortic valve disease (CAVD), the underlying mechanisms of pathogenesis have not been found yet. Therefore, it is extremely important to study CAVD and understand how it develops. For this matter, we decided to study the potential of endothelial progenitor cells (EPCs) for use in tissue-engineered models of heart valves. EPCs were chosen as the cell source of interest for this study due to their high neovascularization potential and use in regenerative medicine and cardiovascular tissue engineering.
In this project, we aimed to engineer the microenvironment of cells that are involved in the formation of heart valves. We hypothesized that cyclic strain induces EPCs to undergo differentiation, which will depend on the applied strain, culture media components and culture duration. EPCs isolated from human umbilical cord blood expressed endothelial cell markers CD31 and vascular endothelial growth factor receptor 2 (VEGFR2), and the progenitor cell marker CD34. The cells did not express the mesenchymal marker α-smooth muscle actin (α-SMA). EPCs showed an endothelial behavior demonstrated by the uptake of acetylated-low density lipoprotein (Dil-Ac-LDL), and a vasculogenic potential demonstrated by tube formation. The cells were subjected to 20% strain rates by utilizing a cyclic uniaxial biostretcher for 7 days and showed a mild expression of α-SMA. Considering these events, EPCs were subjected to 20% strain for longer periods of time (1, 2, and 3 weeks) and showed maintained CD31 expression, no α-SMA expression, and increased CD34 expression suggesting an increased vascular-like behavior after strain
5D Rotating Black Holes and the nAdS/nCFT Correspondence
We study rotating black holes in five dimensions using the nAdS/nCFT
correspondence. A consistent truncation of pure Einstein gravity (with a
cosmological constant) in five dimensions to two dimensions gives a
generalization of the Jackiw-Teitelboim theory that has two scalar fields: a
dilaton and a squashing parameter that breaks spherical symmetry. The interplay
between these two scalar fields is non trivial and leads to interesting new
features. We study the holographic description of this theory and apply the
results to the thermodynamics of the rotating black hole from a two dimensional
point of view. This setup challenges notions of universality that have been
advanced based on simpler models: we find that the mass gap of Kerr-AdS
corresponds to an undetermined effective coupling in the nAdS/nCFT
theory which depends on ultraviolet data.Comment: 49 pages; v2 minor comments and references added; v3 fixed minor
typos in eqs. (4.5) and (4.26
The Spectrum of Static Subtracted Geometries
Subtracted geometries are black hole solutions of the four dimensional STU
model with rather interesting ties to asymptotically flat black holes. A
peculiar feature is that the solutions to the Klein-Gordon equation on this
subtracted background can be organized according to representations of the
conformal group . We test if this behavior persists for the linearized
fluctuations of gravitational and matter fields on static, electrically charged
backgrounds of this kind. We find that there is a subsector of the modes that
do display conformal symmetry, while some modes do not. We also discuss two
different effective actions that describe these subtracted geometries and how
the spectrum of quasinormal modes is dramatically different depending upon the
action used.Comment: 30 pages, 2 figures. v2: references added. v3: minor corrections to
match with published versio
Warped Weyl fermion partition functions
Warped conformal field theories (WCFTs) are a novel class of non-relativistic
theories. A simple, yet non-trivial, example of such theory is a massive Weyl
fermion in -dimensions, which we study in detail. We derive general
properties of the spectrum and modular properties of partition functions of
WCFTs. The periodic (Ramond) sector of this fermionic system is non-trivial,
and we build two novel partition functions for this sector which have no
counterpart in a CFT. The thermodynamical properties of WCFTs are revisited
in the canonical and micro-canonical ensemble.Comment: 41 page
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