Abstract
Cardiac arrhythmias represent about 50% of the cardiovascular diseases which are the first cause of mortality in the world. Implantable medical devices play a major role for treating these ...arrhythmias. Nevertheless the leads induce an unwanted biological phenomenon called fibrosis. This phenomenon begins at a cellular level and is effective at a macroscopic scale causing tissue remodelling with a local modification of the active cardiac tissue. Fibrosis mechanism is complex but at the cellular level, it mainly consists in cardiac fibroblasts activation and differentiation into myofibroblasts. We developed a simplified
in vitro
model of cardiac fibrosis, with human cardiac fibroblasts whom differentiation into myofibroblasts was promoted with TGF-
β
1. Our study addresses an unreported impedance-based method for real-time monitoring of
in vitro
cardiac fibrosis. The objective was to study whether the differentiation of cardiac fibroblasts in myofibroblasts had a specific signature on the cell index, an impedance-based feature measured by the xCELLigence system. Primary human cardiac fibroblasts were cultured along 6 days, with or without laminin coating, to study the role of this adhesion protein in cultures long-term maintenance. The cultures were characterized in the presence or absence of TGF-
β
1 and we obtained a significant cell index signature specific to the human cardiac fibroblasts differentiation.
The degree of collectivity of the Pygmy Dipole Resonance (PDR) is an open question. Recently, Ries {\it et al.} have suggested the onset of the PDR beyond \(N=28\) based on the observation of a ...significant \(E1\) strength increase in the Cr isotopes and proposed that the PDR has its origin in a few-nucleon effect. Earlier, Inakura {\it et al.} had predicted by performing systematic calculations using the random-phase approximation (RPA) with the Skyrme functional SkM* that the \(E1\) strength of the PDR strongly depends on the position of the Fermi level and that it displays a clear correlation with the occupation of orbits with orbital angular momenta less than \(3\hbar\) \((l \leq 2)\). To further investigate the microscopic structures causing the possible formation of a PDR beyond the \(N=28\) neutron shell closure, we performed a \(^{61}\)Ni\((d,p){}^{62}\)Ni experiment at the John D. Fox Superconducting Linear Accelerator Laboratory of Florida State University. To determine the angular momentum transfer populating possible \(J^{\pi} = 1^-\) states and other excited states of \({}^{62}\)Ni, angular distributions and associated single-neutron transfer cross sections were measured with the Super-Enge Split-Pole Spectrograph. A number of \(J^{\pi} = 1^-\) states were observed below the neutron-separation threshold after being populated through \(l=2\) angular momentum transfers. A comparison to available \((\gamma,\gamma')\) data for \({}^{58,60}\)Ni provides evidence that the \(B(E1)\) strength shifts further down in energy. The \((d,p)\) data clearly prove that \(l=0\) strength, i.e., the neutron \((2p_{3/2})^{-1}(3s_{1/2})^{+1}\) one-particle-one-hole configuration plays only a minor role for \(1^-\) states below the neutron-separation threshold in \({}^{62}\)Ni.
Phys. Rev. C 108, 044306 (2023) We performed a measurement of the $^{52}$Cr$(d,p)^{53}$Cr reaction at 16 MeV
using the Florida State University Super-Enge Split-Pole Spectrograph (SE-SPS)
and ...observed 26 states. While all of the states observed here had been seen in
previous $(d,p)$ experiments, we changed five $L$ assignments from those
reported previously and determined $L$ values for nine states that had not had
such assignments made previously.
The $g_{9/2}$ neutron strength observed in $^{53}$Cr in the present work and
in the $N=29$ isotones $^{49}$Ca, $^{51}$Ti, and $^{55}$Fe via $(d,p)$
reactions is much smaller than the sum rule for this strength. Most of the
observed $L=4$ strength in these nuclei is located in states near 4 MeV
excitation energy. The remaining $g_{9/2}$ strength may be located in the
continuum or may be fragmented among many bound states. A covariant density
functional theory calculation provides support for the hypothesis that the
$g_{9/2}$ neutron orbit is unbound in $^{53}$Cr. The ($\alpha,^3$He) reaction
may provide a more sensitive probe for the missing $g_{9/2}$ neutron strength.
In addition, particle-$\gamma$ coincidence experiments may help resolve some
remaining questions in this nucleus.
We report on a highly selective experimental setup for particle-$\gamma$
coincidence experiments at the Super-Enge Split-Pole Spectrograph (SE-SPS) of
the John D. Fox Superconducting Linear ...Accelerator Laboratory at Florida State
University (FSU) using fast CeBr$_3$ scintillators for $\gamma$-ray detection.
Specifically, we report on the results of characterization tests for the first
five CeBr$_3$ scintillation detectors of the CeBr$_3$ Array (CeBrA) with
respect to energy resolution and timing characteristics. We also present
results from the first particle-$\gamma$ coincidence experiments successfully
performed with the CeBrA demonstrator and the FSU SE-SPS. We show that with the
new setup, $\gamma$-decay branching ratios and particle-$\gamma$ angular
correlations can be measured very selectively using narrow excitation energy
gates, which are possible thanks to the excellent particle energy resolution of
the SE-SPS. In addition, we highlight that nuclear level lifetimes in the
nanoseconds regime can be determined by measuring the time difference between
particle detection with the SE-SPS focal-plane scintillator and $\gamma$-ray
detection with the fast CeBrA detectors. Selective excitation energy gates with
the SE-SPS exclude any feeding contributions to these lifetimes.
