Assessment of edema using STIR+ via 3D cardiovascular magnetic resonance imaging in patients with suspected myocarditis

Objective

To evaluate three-dimensional T2-weighted fast spin echo triple inversion recovery sequences (STIR+) for the diagnosis of myocardial edema in patients with suspected early myocarditis after respiratory or gastrointestinal tract viral infection and at follow-up.

Materials and methods

We prospectively examined 28 patients with suspected myocarditis and 37 controls matched for gender and age. An ECG-triggered STIR+ was used to cover the entire left ventricle in short-axis images with 10-mm slice thickness and no interslice gap. The global signal intensity ratio (heart muscle in relation to skeletal muscle) was calculated (global STIR+ ratio) to evaluate edema. All patients had repeat examinations at follow-up (mean interval 4.9 months, 1–12 months).

Results

The mean global STIR+ ratio was 2.15 ± 0.4 in the initial examination of patients as compared to 1.78 ± 0.3 in controls (p < 0.0001) and 1.89 ± 0.3 in patients at follow-up (p = 0.0001 vs. first visit). Left ventricular ejection fraction did not differ between patients and controls at baseline and at follow-up.

Conclusion

We could identify a significantly higher global STIR+ ratio in patients with suspected myocarditis compared to controls, and a dynamic change during follow-up. The global STIR+ ratio may, therefore, be useful for the diagnosis of myocarditis and should be further explored.

     

The Vortex Path Model Analysis of the Field Angle Dependence of the Critical Current Density in Nanocomposite YBa2Cu3 O 7−x – BaZrO3 Films Obtained by Low Fluorine Chemical Solution Deposition

In the present paper, we analyze the role of in situ grown BaZrO₃ (BZO) inclusions in YBa₂Cu₃O_7?x (YBCO) thin films prepared by chemical solution deposition using a low fluorine coating solution, on the field angle dependence of the critical current density, J _c (??), data using the vortex path model. In order to form a coherent picture on the BZO doping influence on the pinning properties of the YBCO matrix, detailed structural analyses performed by X-ray diffraction techniques and microstructural evaluation by transmission electron microscopy are also presented. The evaluation of different contributions to the overall, J _c , permitted us to prove the effectiveness of the BZO inclusions acting as isotropic pinning centers, reflected in a uniform component of high relative value with respect to other components. For the studied 10 mol % BZO doping concentration, a threefold increase in the critical current density, J _c , of the YBCO host is measured, in self-field at 77 K, corresponding to a value of J _c =2.9MA/cm², whereas a factor 10 is measured at 1 T (J _c =0.35 MA/cm²).     

Switched-Capacitor Track-and-Hold Amplifiers With Low Sensitivity to Op-Amp Imperfections

This paper describes high-precision switched-capacitor (SC) track-and-hold amplifier (THA) stages. They use a novel continuous-time correlated double sampling (CDS) scheme to desensitize the operation to amplifier imperfections. Unlike earlier predictive-CDS amplifiers, the circuits do not need a sampled-and-held input signal for their operation. During the tracking period, an auxiliary continuous-time signal path is established, which predicts the output voltage during the holding period. This allows accurate operation even for low amplifier gains and large offsets over a wide input frequency range. Extensive simulations were performed to compare the performance of the proposed THAs with earlier circuits utilizing CDS. The results verify that their operation is far more robust than that of any previously described SC amplifiers     

In situ electrochemical impedance spectroscopy of Zr–1%Nb under VVER primary circuit conditions

Oxide layers were grown on tubular samples of Zr–1%Nb under conditions simulating those in VVER-type pressurised water reactors, viz. in near-neutral borate solutions in an autoclave at 290 °C. These samples were investigated using electrochemical impedance spectroscopy which was found to be suitable to follow in situ the corrosion process. A –CPE_oxR_ox– element was used to characterise the oxide layer on Zr–1%Nb. Both the CPE_ox coefficient, σ_ox, and the parallel resistance, R_ox, were found to be thickness dependent. The layer thickness, however, can only be calculated after a calibration procedure. The temperature dependence of the CPE_ox element was also found to be anomalous while the temperature dependence of R_ox indicates that the oxide layer has semiconductor properties. The relaxation time – defined as (R_oxσ_ox)^1/ – was found to be quasi-independent of oxidation time and temperature; thus it is characteristic to the oxide layer on Zr–1%Nb.     

Neural network methods for the modeling and control of welding processes

While welding processes are of great importance in manufacturing, their modeling and control is still subject of research. The highly nonlinear, strongly coupled, and multivariable nature of these processes renders the use of analytical tools practically impossible. In this article a novel approach is presented which employs networks of simple nonlinear units: a neural network. A widely used welding process, the Gas Tungsten Arc Welding is presented and the problem of its modeling and control is exhibited. A very brief introduction to neural networks is followed by presenting the experimental results for modeling the static and dynamic behavior of the process, as well as some practical recommendations regarding the use of the neural network techniques for controlling these processes.     

Hot-wire chemical vapor deposition of high hydrogen content silicon nitride for solar cell passivation and anti-reflection coating applications

The stoichiometry and hydrogen content of hot-wire (HW)-grown silicon nitride was examined as a function of SiH₄/NH₃ flow ratio. The effect of post-deposition hydrogenation treatment on overall film hydrogen content was determined. The hydrogen release properties in Si-rich and N-rich nitride layers were characterized by annealing treatments. Defect hydrogenation was studied using Fourier transform infrared spectroscopy on platinum-diffused silicon substrates. HW nitride layers were deposited onto diffused emitter String Ribbon silicon substrates, producing cells with comparable short circuit current density, open circuit voltage, fill-factor, and efficiency to those fabricated using plasma chemical vapor deposition nitride layers.