We present the transverse momentum spectra and rapidity distributions of {pi}{sup -} and K{sub S}{sup 0} in Ar + KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the High ...Acceptance Di-Electron Spectrometer (HADES). The reconstructed K{sub S}{sup 0} sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental {pi}{sup -} and K{sub S}{sup 0} distributions to predictions by the Isospin Quantum Molecular Dynamics (IQMD) model. The model calculations show that K{sub S}{sup 0} at low transverse momenta constitute a particularly well-suited tool to investigate the kaon in-medium potential. Our K{sub S}{sup 0} data suggest a strong repulsive in-medium K{sup 0} potential of about 40 MeV strength.
We present transverse momentum spectra, rapidity distribution and multiplicity of Lambda-hyperons measured with the HADES spectrometer in the reaction Ar(1.76A GeV)+KCl. The yield of Xi- is ...calculated from our previously reported Xi-/(Lambda+Sigma0) ratio and compared to other strange particle multiplicities. Employing a strangeness balance equation the multiplicities of the yet unmeasured charged Sigma hyperons can be estimated. Finally a statistical hadronization model is used to fit the yields of pi-, K+, K0s, K-, phi, Lambda and Xi-. The resulting chemical freeze-out temperature of T=(76+-2) MeV is compared to the measured slope parameters obtained from fits to the transverse mass distributions of the particles.
We present the transverse momentum spectra and rapidity distributions of \(\pi^{-}\) and K\(^0_S\) in Ar+KCl reactions at a beam kinetic energy of 1.756 A GeV measured with the spectrometer HADES. ...The reconstructed K\(^0_S\) sample is characterized by good event statistics for a wide range in momentum and rapidity. We compare the experimental \(\pi^{-}\) and K\(^0_S\) distributions to predictions by the IQMD model. The model calculations show that K\(^0_S\) at low tranverse momenta constitute a particularly well suited tool to investigate the kaon in-medium potential. Our K\(^0_S\) data suggest a strong repulsive in-medium K\(^0\) potential of about 40 MeV strength.
HADES is a versatile magnetic spectrometer aimed at studying dielectron production in pion, proton and heavy-ion induced collisions. Its main features include a ring imaging gas Cherenkov detector ...for electron-hadron discrimination, a tracking system consisting of a set of 6 superconducting coils producing a toroidal field and drift chambers and a multiplicity and electron trigger array for additional electron-hadron discrimination and event characterization. A two-stage trigger system enhances events containing electrons. The physics program is focused on the investigation of hadron properties in nuclei and in the hot and dense hadronic matter. The detector system is characterized by an 85% azimuthal coverage over a polar angle interval from 18 to 85 degree, a single electron efficiency of 50% and a vector meson mass resolution of 2.5%. Identification of pions, kaons and protons is achieved combining time-of-flight and energy loss measurements over a large momentum range. This paper describes the main features and the performance of the detector system.
We present phase space distributions and multiplicities of K+, K- and phi mesons produced in Ar+KCl reactions at a kinetic beam energy of 1.756 AGeV and measured with the HADES spectrometer. The ...inverse slope parameters and yields of kaons supplement the systematics of previous measurements. The percentage of K- mesons coming fromphi decay is found to be 18+- 7%.
The significance of cardiac stem cell (CSC) populations for cardiac regeneration remains disputed. Here, we apply the most direct definition of stem cell function (the ability to replace lost tissue ...through cell division) to interrogate the existence of CSCs. By single-cell mRNA sequencing and genetic lineage tracing using two Ki67 knockin mouse models, we map all proliferating cells and their progeny in homoeostatic and regenerating murine hearts. Cycling cardiomyocytes were only robustly observed in the early postnatal growth phase, while cycling cells in homoeostatic and damaged adultmyocardium represented various noncardiomyocyte cell types. Proliferative postdamage fibroblasts expressing follistatin-like protein 1 (FSTL1) closely resemble neonatal cardiac fibroblasts and form the fibrotic scar. Genetic deletion of Fstl1 in cardiac fibroblasts results in postdamage cardiac rupture. We find no evidence for the existence of a quiescent CSC population, for transdifferentiation of other cell types toward cardiomyocytes, or for proliferation of significant numbers of cardiomyocytes in response to cardiac injury.
Arterial spin labeling (ASL) perfusion is a MRI technique to quantify tissue blood flow. ASL is a non-invasive technique that labels the protons in the arterial blood by radiofrequency pulses, ...without the exogenous injection of contrast media. This article has three goals: 1) present the principles of ASL perfusion, the types of labeling and the ways to obtain the mapping; 2) specify and the quality criteria for the mapping obtained, while emphasizing the artifacts; and 3) describe the main encephalic and renal applications.
Multiple sclerosis MS is a common inflammatory, demyelinating and neurodegenerative disease of the central nervous system that affects both the brain and the spinal cord. In clinical practice, spinal ...cord MRI is performed far less frequently than brain MRI, mainly owing to technical limitations and time constraints. However, improvements of acquisition techniques, combined with a strong diagnosis and prognostic value, suggest an increasing use of spinal cord MRI in the near future. This review summarizes the current data from the literature on the prognostic value of spinal cord MRI in MS patients in the early and later stages of their disease. Both conventional and quantitative MRI techniques are discussed. The prognostic value of spinal cord lesions is clearly established at the onset of disease, underlining the interest of spinal cord conventional MRI at this stage. However, studies are currently lacking to affirm the prognostic role of spinal cord lesions later in the disease, and therefore the added value of regular follow-up with spinal cord MRI in addition to brain MRI. Besides, spinal cord atrophy, as measured by the loss of cervical spinal cord area, is also associated with disability progression, independently of other clinical and MRI factors including spinal cord lesions. Although potentially interesting, this measurement is not currently performed as a routine clinical procedure. Finally, other measures extracted from quantitative MRI have been established as valuable for a better understanding of the physiopathology of MS, but still remain a field of research.
Objective
To validate the proton density fat fraction (PDFF) obtained by the MRQuantif software from 2D chemical shift encoded MR (CSE–MR) data in comparison with the histological steatosis data.
...Methods
This study, pooling data from 3 prospective studies spread over time between January 2007 and July 2020, analyzed 445 patients who underwent 2D CSE–MR and liver biopsy. MR derived liver iron concentration (MR–LIC) and PDFF was calculated using the MRQuantif software. The histological standard steatosis score (SS) served as reference. In order to get a value more comparable to PDFF, histomorphometry fat fraction (HFF) were centrally determined for 281 patients. Spearman correlation and the Bland and Altman method were used for comparison.
Results
Strong correlations were found between PDFF and SS (
r
s
= 0.84,
p
< 0.001) or HFF (
r
s
= 0.87,
p
< 0.001). Spearman’s coefficients increased to 0.88 (
n
= 324) and 0.94 (
n
= 202) when selecting only the patients without liver iron overload. The Bland and Altman analysis between PDFF and HFF found a mean bias of 5.4% ± 5.7 95% CI 4.7, 6.1. The mean bias was 4.7% ± 3.7 95% CI 4.2, 5.3 and 7.1% ± 8.8 95% CI 5.2, 9.0 for the patients without and with liver iron overload, respectively.
Conclusion
The PDFF obtained by MRQuantif from a 2D CSE–MR sequence is highly correlated with the steatosis score and very close to the fat fraction estimated by histomorphometry. Liver iron overload reduced the performance of steatosis quantification and joint quantification is recommended. This device-independent method can be particularly useful for multicenter studies.
Clinical relevance statement
The quantification of liver steatosis using a vendor-neutral 2D chemical-shift MR sequence, processed by MRQuantif, is well correlated to steatosis score and histomorphometric fat fraction obtained from biopsy, whatever the magnetic field and the MR device used.
Key Points
•
The PDFF measured by MRQuantif from 2D CSE–MR sequence data is highly correlated to hepatic steatosis.
•
Steatosis quantification performance is reduced in case of significant hepatic iron overload.
•
This vendor-neutral method may allow consistent estimation of PDFF in multicenter studies.
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