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A. Nieto

Publications and source records attributed to A. Nieto.

3 recordsLinked to original sources

Finite element simulation of the structural integrity of endothelial cell monolayers: a step for tumor cell extravasation

Cell extravasation is a crucial step of the metastatic cascade. In this process, the circulating tumor cells inside the blood vessels adhere to the cell monolayer of the blood vessel wall and passes through it, which allows them to invade different organs and complete metastasis. In this process, it is relevant to understand how the adhesions between cells that form the endothelial monolayer are broken, resulting in intra-cellular gaps through which tumor cells are able to extravasate the blood vessel wall. Within this process, we focus on studying the dynamics of cell-cell junctions rupture produced in the endothelial monolayer by the effect of Calcium waves. The regulation of this monolayer is of vital importance, not only in metastasis, but also in diseases such as pulmonary edema or atherosclerosis. In order to understand this rupture dynamics in greater depth, we propose a hybrid model that simulates endothelial cells as \textcolor{black}{an} elastic material and cell-cell adhesions of the monolayer by means of a catch bond law. We study the effects that the cell contraction caused by a Calcium wave presents on the endothelial monolayer depending on the diameter of the blood vessel. For this purpose, we develop a three-dimensional model to study the effect of the different blood vessel diameters. The results indicate that there are greater tractions on the joints located in vertices common to several cells. This led to the formation of openings in the endothelial monolayer, through which extravasation of tumor cells could occur. For the different geometries studied, no significant effect of the blood vessel diameter on the rupture of the adhesions of monolayer is observed.

q-bio.TO

RMATE: A device to test radiation-induced effects under controlled magnetic field and temperature

This study shows the development and performance assessment of a novel set-up that enables the research of structural materials for fusion reactors, by making possible simultaneous application of temperature (up to 450$^{\circ}$C) and magnetic field (close to 0.6 T) during irradiation experiments. These aspects become critical as structural materials in fusion reactors are exposed to intense radiation levels under the presence of strong magnetic fields. Moreover, material microstructural could be modified by radiation-induce propagating defects, which are thought to be sensitive to magnetic field. The device has three main components: magnetic closure, sample holder with integrated heater, and radiation shield. It is provided with a thermal shield to prevent other elements of the device to heat up and fail. A mapping of the magnetic flux in the region where sample and heater are located has been modeled by finite elements simulation software and correlated with magnetic measurements

physics.ins-det

Dual Description of Supergravity MacDowell-Mansouri Theory

In the context of field theory two elements seem to be necessary to search for strong-weak coupling duality. First, a gauge theory formulation and second, supersymmetry. For gravitation these two elements are present in MacDowell-Mansouri supergravity. The search for an "effective duality" in this theory presents technical and conceptual problems that we discuss. Nevertheless, by means of a field theoretical approach, which in the abelian case coincides with $S$-duality, we exhibit a dual theory, with inverted couplings. This results in a supersymmetric non-linear sigma model of the Freedman-Townsend type.

hep-th