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A technique based on the anomalous sensitivity of the effective electrical conductivity of semiconductors is proposed for determining random irregularities in such devices. A relation was developed to evaluate small effective conductivity while an inhomogeneous concentration of carriers were established using nonuniform illumination of homogeneous semiconductors. Results indicated that the method is highly effective in determining microinhomogeneities in semiconductors.

Background: The noninvasive detection of restenosis after percutaneous coronary intervention (PCI) remains a clinical challenge. Previous studies have shown that magnetocardiograms reveal obvious changes in patients with coronary artery disease (CAD) and normal electrocardiogram (ECG) at rest.Hypothesis: The present study aimed to evaluate the potential of magnetocardiography (MCG) for the detection of electrophysiological changes in the course of successful PCI.Methods: Twelve-lead ECG and unshielded four-channel MCG (SQUID AG, Essen, Germany) were registered at nine prethoracic sites in 50 patients with CAD (62 +/- 10 years; EF = 76 +/- 11%; registration: before, 24 hours, and 1 month (n = 25) after PCI) and 57 normals (51 +/- 9 years). Current density vector (CDV) maps were reconstructed within the ST-T interval and classified from category 0 (normal) to category 4 (grossly abnormal). In both groups and at all registration times, the percentage of each category of maps was calculated and compared.Results: Most CDV maps of normals were classified as category 0, 1, or 2 compared to CAD patients before PCI with most maps of category 3 and 4 (P < 0.0005). Twenty-four hours after PCI, more maps were classified as category 2 (P < 0.05) and less as category 4 (P < 0.005). One month after PCI the MCG results further improved: more maps were classified as category 1 (P < 0.05) and 2 (P < 0.005) and less maps as category 4 (P < 0.0001). The ECG remained unchanged in the course of PCI.Conclusion: Unshielded four-channel MCG reveals obvious changes in the course of successful PCI on the basis of CDV map reconstruction during repolarization. The method seems to be suitable for the follow-up of patients after PCI. [ABSTRACT FROM AUTHOR]

Introduction: In the principles of the organization of armed struggle of the defense forces of most developed countries of the world, considerable attention is paid to the evaluation of combat readiness of the military personnel. This procedure is conditioned by such interconnected goals of the armed struggle as the maximum realization of the combat potential and the minimization of personnel losses. The purpose of the work is to determine the physiological cost of the activities of the soldiers of the Defense Forces of Ukraine with the help of miniature electrocardiographic hardware and software complexes., Methods: In the research, ultra-miniature ECG devices worn on the body for a long time, so-called wearable "on-body" ECG patch devices, were used in various combat conditions. When analyzing the data, the principle of multi-faceted ECG analysis was implemented, which allows you to obtain complete and physiologically based information, which includes 4 blocks: heart rate variability (HRV), amplitude-time indicators of the ECG, heart rhythm disorders, and psycho- emotional state., Results: In this study, a complex index of the functional state formed based on estimates of generally accepted and original indicators of heart rhythm variability, the shape of the teeth and complexes of the electrocardiogram, as well as an index of the psycho-emotional state formed according to the same principles based on the analysis of heart rhythm variability according to the modified McCraty algorithm (USA) was evaluated. Examination with the help of the complex is carried out in a state of rest, sitting or lying down., Discussion: The sensitivity of the developed monitoring system is good enough to detect the changes in the functional state both in the case of short-term (for hours) intense physical or psycho-emotional stress and more chronic (for days and weeks) stress depending on the nature of the task being done. The proposed methods and means can be considered an important tool to support the commander's decision-making regarding the ability of personnel from the point of view of their functional state to perform combat tasks., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Bocharov, Stasiuk, Osyodlo, Ryzhenko, Malanin, Chumachenko and Chaikovsky.)

Magnetocardiography is a modern method of registration of the magnetic component of electromagnetic field, generated by heart activity. Magnetocardiography results are a useful source for the diagnosis of various heart diseases and states, but their usage is still undervalued in the cardiology community. In this study, a two-stage classification by correlation analysis using a k-Nearest Neighbor (k-NN) algorithm is applied for the binary classification of myocardium current density distribution maps (CDDMs). Fourteen groups of CDDMs from patients with different heart states, healthy volunteers, sportsmen, patients with negative T-peak, patients with myocardial damage, male and female patients with microvascular disease, patients with ischemic heart disease, and patients with left ventricular hypertrophy, divided into five and three different groups depending on the degree of pathology, were compared. Selection of best metric, used in classifier and number of neighbors, was performed to define the classifier with best performance for each pair of heart states. Accuracy, specificity, sensitivity, and precision values dependent on the number of neighbors are obtained for each class. The proposed method allows to obtain a value of average accuracy equal to 96%, 70% sensitivity, 98% specificity, and 70% precision., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Udovychenko, Popov and Chaikovsky.)

The article is devoted to clinical--economic analysis of modern diagnostic technology--magnetocardiography by analyzing the "cost-effectiveness". Economic effectiveness of diagnosis of coronary artery disease using magnetocardiography in terms of cost/effectivness is shown. The economicaly optimal sequence of several noninvasive methods for diagnosis of coronary artery disease is defined.

Introduction: The aim of this paper is to investigate the predictive value of the new integrated magnetocardiographic (MCG) index (CI) in the diagnosis of coronary artery disease (CAD) in patients with suspected CAD with intermediate pretest probability of the disease and uninformative results of routine tests., Patients and Methods: The study was carried out in the Clinic of Cardiology of the Main Military Clinical Hospital of Ukraine, Kiev (clinic 1), and in the Second Medical Clinic of the 'Katholisches Klinikum Essen', Germany (clinic 2).The main group (group 1) included 89 patients without a history of myocardial infarction. Coronary angiography was performed because of chest pain. Depending on the results of coronary angiography, this group was divided into two subgroups: (i) those with at least 70% stenosis in at least one of the main coronary arteries (subgroup 1a) and (ii) those without hemodynamically significant stenosis (subgroup 1b). The control group included 43 healthy volunteers.In all participants, the MCG examination was performed using a seven-channel MCG system located in an unshielded room. An integrated MCG index (CI), consisting of six parameters, was calculated., Results: It can be shown that CI was significantly higher in patients with stenosis 70% or more compared with the patients without stenosis and healthy volunteers. Sensitivity was 93%, specificity was 84%, positive predictive value was 85%, and negative predictive value was 93%., Conclusion: The MCG test at rest has the potential to be useful in the noninvasive diagnosis of CAD in patients with intermediate pretest probability of disease and uninformative results of routine tests.

Background: The diagnostic management of patients with chest pain remains a clinical challenge. Magnetocardiography (MCG) is a noninvasive method for the recording of cardiac electromagnetic signals at multiple sites above the chest cage. Contrary to electrocardiogram (ECG) the magnetic field is unaltered by surrounding tissues. The present study aimed to analyze the diagnostic value of an unshielded four-channel MCG for the detection of coronary artery disease (CAD) in patients with chest pain., Methods: The study included 417 subjects: 177 patients with angiographically documented CAD (stenoses > or =50%), 123 symptomatic patients without hemodynamically relevant stenosis (nCAD) and 117 healthy subjects. Twelve-lead ECG was obtained in all subjects. The magnetocardiography recordings were taken from 36 positions at rest. From these current density vector maps were generated during the ST-T interval. Each map was classified using a classification system with a scale from 0 (normal) to 4 (grossly abnormal)., Results: While the ECG was normal in all subjects the MCG revealed typical differences. In normals most maps were classified as category 0, 1 or 2, in nCAD and more so in CAD patients the categories 3 and 4 prevailed. Using a cut-off value of 39.2% for the discrimination between normals and CAD patients sensitivity was 73.3%, specificity 70.1%., Conclusion: Contrary to ECG, unshielded MCG reveals significant differences between normals and symptomatic patients with and without relevant stenoses using current density reconstruction during repolarization at rest. This method might be a suitable noninvasive tool for the management of patients with chest pain.

Background: The noninvasive detection of coronary artery disease (CAD) remains a clinical challenge. Magnetocardiography is a completely noninvasive method that permits the registration of cardiac electrical activity at multiple sites in a plane above the chest cage without the need for electrodes. In contrast to the electrocardiogram (ECG) which suffers from boundary effects and a variety of potential artifacts (electrode placement, etc.) the MCG is unaffected by such impediments as the magnetic field is unaltered by surrounding tissues., Hypothesis: Magnetocardiography with a newly developed single-channel system in an unshielded setting should be a better qualitative diagnostic tool than the standard ECG for the detection and assessment of CAD., Methods: In all, 52 patients with angiographically documented CAD and unimpaired ventricular function as well as 55 controls were included in this study. A standard 12-lead ECG was obtained in all subjects. The MCG recordings were taken from 36 positions under resting conditions. From these, current density vector maps were generated during the ST-T interval. Each map was then classified using a classification system with a scale from 0 (normal) to 4 (grossly abnormal)., Results: While the ECG was normal in all subjects, the MCG in the controls was classified as category 0, 1, or 2. However, in patients with abnormal coronary angiograms, mainly maps in categories 3 and 4 were seen (p < 0.05)., Conclusion: A single-channel magnetometer in an unshielded setting reveals significant differences between normals and patients with CAD with normal ECG on the basis of current density reconstruction during the ST segment when measured under resting conditions. This method might be suitable for the noninvasive detection of CAD.

Background: Of the donor corneas rejected for transplantation, the largest group is that from donors testing seropositive for hepatitis C virus (HCV). In situations of severe shortage in supply of donor corneal tissue, we may consider the use of seropositive donors for transplantation if we can prove with high certainty the absence of HCV RNA in the donor corneal tissue. Polymerase chain reaction (PCR) is a highly sensitive and specific technique for direct detection of HCV RNA and can be used for this purpose. Nevertheless, it is not applicable for routine clinical use in most eye departments due to its unavailability and cost effectiveness. Purpose: To study the possible use of immunohistochemical method for detection of HCV antigen in corneal tissue of seropositive donors and correlate the results with those of PCR. Immunohistochemical methods have not yet been studied in donor corneal tissue. Materials and methods: Eight corneas of 4 seropositive and 8 corneas of 4 seronegative corneal donors were studied by immunohistochemical and PCR methods for the presence of HCV antigen in their corneal tissue and sera. Results: HCV RNA was not detected in the sera and corneal tissue of all seropositive and seronegative corneal donors by either PCR and immunohistochemical methods. Conclusion: Although the study is too small for conclusive results, the correlation between the immunohistochemical and PCR studies for direct detection of HCV antigen in corneal tissue of seropositive donors may raise the possibility of using the immunohistochemical method for screening of donor corneas for the detection of HCV antigen. A larger prospective study investigating the sensitivity, specificity and clinical applicability of the immunohistochemical method is warranted.