Electrodynamic Model of the Heart to Detect Necrotic Areas in a Human Heart

To diagnose the conditions and diseases of the cardiovascular system is the main task of electrocardiology. The problem of the cardiovascular system diagnostics is caused by a complex multi-level mechanism of its functioning, and only experienced specialists are able to establish a correct diagnosis. Since the working heart is inaccessible to direct observations in real life, diagnostics of diseases is based on noninvasive methods such as electrocardiography. By assumption, weak "bursts" (micropotentials) of electrocardiographic signals in different areas are the precursors of dangerous arrhythmias. The amplitude of these signals on the body surface is insignificant and tends to be commensurate with the noise level of the measuring system. Advances in electrocardiography make it possible to generate a high resolution ECG signal and to detect the heart micropotentials. The method of modeling helps to understand causes of micropotentials in the ECG signal by selecting the model parameters. The model of the heart should allow generating a signal close to the high resolution ECG signal. The research aims to find a numerical model that allows solving the inverse problem of the heart tissue characteristics recovery using a high resolution ECG signal and CT data on the heart geometry. The proposed computer model and highly sensitive methods for the ECG measurement are the part of the hardware-software complex to detect dangerous precursors of cardiac arrhythmias

Loneliness and social isolation during the COVID-19 pandemic

The outbreak of the global COVID-19 pandemic has drastically altered people's lives. Loneliness and social isolation were publicly discussed as possible psychological consequences of the measures taken to slow the virus spread. These public discussions have sparked a surge in empirical studies on loneliness and social isolation. In this study, we first provide a systematic review synthesizing recent literature on the prevalence and correlates of loneliness and social isolation during the early phase of the COVID-19 pandemic ($\it k$ = 53 studies). We found that most quantitative studies included in the systematic review were cross-sectional. The few longitudinal studies mainly reported increases in loneliness, especially when the pre-pandemic measurement occasions were months or years before the COVID-19 pandemic. Studies with pre-pandemic measures weeks or days before the pandemic reported relatively stable or even decreasing loneliness trends. Second, we enrich the systematic review with an empirical investigation on daily changes in the perceived quality and quantity of social relationships during the pandemic compared to before the pandemic ($\it N$ = 4,823). This empirical investigation showed that, on average, the quality of social relationships was perceived worse during the pandemic than before. This perception got slightly stronger over the first 2 weeks of the pandemic but stagnated thereafter. Regarding the quantity of social relationships, participants reported on average that they had fewer social interactions at the beginning of the study than before the pandemic. This perceived reduction in the quantity of social interactions linearly decreased over time

Neutron and X-ray Diffraction Analysis of Macro and Phase-Specific Micro Residual Stresses in Deep Rolled Duplex Stainless Steels

Experimental analyses of depth distributions of phase-specific residual stresses after deep rolling were carried out by means of laboratory X-ray diffraction and neutron diffraction for the two duplex steels X2CrNiMoN22-5-3 and X3CrNiMoN27-5-2, which differ significantly in their ferrite to austenite ratios. The aim of the investigation was to elucidate to which extent comparable results can be achieved with the destructive and the non-destructive approach and how the process induced phase-specific micro residual stresses influence the determination of the phase- and {hkl}-specific reference value d0, required for evaluation of neutron strain scanning experiments. A further focus of the work was the applicability of correction approaches that were developed originally for single-phase materials for accounting for spurious strains during through surface neutron scanning experiments on coarse two-phase materials. The depth distributions of macro residual stresses were separated from the phase-specific micro residual stresses. In this regard, complementary residual stress analysis was carried out by means of incremental hole drilling. The results indicate that meaningful macro residual stress depth distributions can be determined non-destructively by means of neutron diffraction for depths starting at about 150–200 µm. Furthermore, it was shown that the correction of the instrumental surface effects, which are intrinsic for surface neutron strain scanning, through neutron ray-tracing simulation is applicable to multiphase materials and yields reliable results. However, phase-specific micro residual stresses determined by means of neutron diffraction show significant deviations to data determined by means of lab X-ray stress analysis according to the well-known sin2ψ-method