On the fetal magnetocardiogram

Fetal magnetocardiography is a non-invasive technique for studying the electrical activity of the fetal heart. Fetal magnetocardiograms (fMCG) can be used to diagnose and classify fetal cardiac arrhythmias reliably. An averaged fMCG shows a QRS-complex, a P-wave, and a T-wave. However, it is still unknown if the currents in the tissues surrounding the fetal heart disturb these features. Furthermore, the measuring technique is not yet optimised for fMCG registrations. Simulation studies may provide guidelines for the design of an appropriate magnetometer system. Therefore, finite-element and boundary-element models were constructed in order to study the possible influence of the volume conductor. Especially, the influence of the layer of vernix caseosa, a fatty layer that covers the fetus, was investigated. The computations showed that the layer of vernix caseosa will affect the waveform of the fMCG. The signal processing procedure used is also discussed. It turned out to be difficult to deduce the onset and offset of the T-wave from the resulting averaged signals. Possibly, the QRS-complex does not provide a correct trigger to obtain a distinguishable T-wave in the averaged signal, because the RT-interval may be variable

Effects of inhomogeneities within the brain on EEG and MEG

The influence of ventricles and lesions on MEG and EEG is studied. The ventricles have an intricate shape and are filled with cerebrospinal fluid. Lesions can have various shapes and their conductivity is unknown. A realistically shaped three-compartment model is used, describing the scalp, skull and brain, which includes the realistically shaped ventricles or a spherical lesion. The potential is computed by means of the finite-element method, and the magnetic field by applying the law of Biot-Savart (Broek, S.P.v.d., Zhou, H. and Peters, M.J. 1996, computation of neuromagnetic fields using finite-element method and Biot-Savart law, Med. Biol. Eng. Comput., 34,21-26). An influence of the ventricles on the potential is only noticeable for dipoles that are within a few centimetres of a ventricle and on the relatively weak potentials on the opposite side of the head. The 'radial' component of the magnetic field generated by superficial dipoles is not influenced by the ventricles in a healthy subject. The influence on the other components, and on the field generated by dipoles near the ventricles can be large. A lesion has a large effect on the potential for sources near the lesion. The effects on the MEG are smaller, but noticeable. Care should be taken in explaining abnormalities in EEGs and MEGs, as it is possible that they are caused by the presence of an inhomogeneity

The influence of inhomogeneities in a head model on EEG and MEG

A realistically shaped model of the head, consisting of tetrahedral elements, is used to investigate the influence of inhomogeneities in the volume conductor (e.g., ventricles and holes) on EEG and MEG. The potential is computed using the finite-element method. The magnetic field is calculated from this potential distribution, applying the law of Biot-Savart. In order to study the influence of the ventricles, computations are carried out using two models: one in which the elements within the ventricles are given the same conductivity as the brain and one in which these elements have a higher conductivity. The influence of holes in the skull layer is examined by giving some elements in the skull layer the same conductivity as that of the brain. The geometry of compartments is obtained semiautomatically from Magnetic Resonance Imaging (MRI) scans. The surface of the ventricles is obtained by manually selecting points on the interface between ventricle and brain. The computation time depends on the total number of tetrahedrons. Therefore, the vertices are distributed in, such a way that a sufficiently high accuracy is obtained with as few tetrahedrons as possible

Blood coagulation and beyond: position paper from the fourth Maastricht consensus conference on thrombosis

The Fourth Maastricht Consensus Conference on Thrombosis included the following themes. Theme 1: The "coagulome" as a critical driver of cardiovascular disease. Blood coagulation proteins also play divergent roles in biology and pathophysiology, related to specific organs, including brain, heart, bone marrow, and kidney. Four investigators shared their views on these organ- specific topics. Theme 2: Novel mechanisms of thrombosis. Mechanisms linking factor XII to fibrin, including their structural and physical properties, contribute to thrombosis, which is also affected by variation in microbiome status. Virus infection-associated coagulopathies perturb the hemostatic balance resulting in thrombosis and/ or bleeding. Theme 3: How to limit bleeding risks: insights from translational studies. This theme included state-of- the- art methodology for exploring the contribution of genetic determinants of a bleeding diathesis; determination of polymorphisms in genes that control the rate of metabolism by the liver of P2Y12 inhibitors, to improve safety of antithrombotic therapy. Novel reversal agents for direct oral anticoagulants are discussed. Theme 4: Hemostasis in extracorporeal systems: the value and limitations of ex vivo models. Perfusion flow chamber and nanotechnology developments are developed for studying bleeding and thrombosis tendencies. Vascularized organoids are utilized for disease modeling and drug development studies. Strategies for tackling extracorporeal membrane oxygenation-associated coagulopathy are discussed. Theme 5: Clinical dilemmas in thrombosis and antithrombotic management. Plenary presentations addressed controversial areas, i. e., thrombophilia testing, thrombosis risk assessment in hemophilia, novel antiplatelet strategies, and clinically tested factor XI(a) inhibitors, both possibly with reduced bleeding risk. Finally, COVID- 19-associated coagulopathy is revisited.Nephrolog

SARS-CoV-2 infects the human kidney and drives fibrosis in kidney organoids

Kidney failure is frequently observed during and after COVID-19, but it remains elusive whether this is a direct effect of the virus. Here, we report that SARS-CoV-2 directly infects kidney cells and is associated with increased tubule-interstitial kidney fibrosis in patient autopsy samples. To study direct effects of the virus on the kidney independent of systemic effects of COVID-19, we infected human-induced pluripotent stem-cell-derived kidney organoids with SARS-CoV-2. Single-cell RNA sequencing indicated injury and dedifferentiation of infected cells with activation of profibrotic signaling pathways. Importantly, SARS-CoV-2 infection also led to increased collagen 1 protein expression in organoids. A SARS-CoV-2 protease inhibitor was able to ameliorate the infection of kidney cells by SARS-CoV-2. Our results suggest that SARS-CoV-2 can directly infect kidney cells and induce cell injury with subsequent fibrosis. These data could explain both acute kidney injury in COVID-19 patients and the development of chronic kidney disease in long COVID

Volume conduction effects in EEG and MEG

Volume conductor models that are commonly used to describe the EEG and MEG neglect holes in the skull, lesions, the ventricles, and anisotropic conductivity of the skull. To determine the influence of these features, simulations were carried out using the finite element method. The simulations showed that a hole in the skull will have a large effect on the EEG, and as one of the consequences localisation errors up to 15 mm may occur. The effect on the MEG is negligible. The presence of a lesion may cause the shape and magnitude of the EEG and MEG to change. Hence, a lesion has to be taken into account, if the active neurones are close to it. Moreover, a localisation procedure may fail if the lesion is not included in the volume conductor model. Inclusion of the ventricles in the volume conductor model is necessary only if sources are in their vicinity or if their sizes are unusually large. Anisotropic conductivity of the skull has a smearing effect on the EEG but does not influence the MEG

Het bustaxi communicatie systeem: Berichten uitwisseling tussen centrale en paal

Uitgangspunt bij de beschouwingen in dit verslag is een bustaxisysteem met 100-200 kiespalen, 20-50 bustaxi's en 1 centrale. Een klant kan via een paal een oproep doen, waarna de centrale hem een bustaxi toewijst en via een inductielus bij een paal een bustaxi opdraagt hem af te halen. Vanwege de kosten kunnen het best groepen van 25 palen via een stervormig telefoonhuurlijnennet door de centrale afgevraagd worden. SDLC/HDLC geeft regels voor een correcte communicatie. Bij half duplex en 2400 bps seinsnelheid krijgt een klant in + 2 seconden een bustaxi toegewezen. Verdere eisen t.a.v. een lijnaanpassing (modem) worden opgesteld . Een proefopstelling van centrale en een paal werkt naar verwachting.Electrical Engineering, Mathematics and Computer ScienceAutomatische Verkeerssysteme

A multi-sensor scenario for coastal surveillance

Maritime borders and coastal zones are susceptible to threats such as drug trafficking, piracy, undermining economical activities. At TNO Defence, Security and Safety various studies aim at improving situational awareness in a coastal zone. In this study we focus on multi-sensor surveillance of the coastal environment. We present a study on improving classification results for small sea surface targets using an advanced sensor suite and a scenario in which a small boat is approaching the coast. A next generation sensor suite mounted on a tower has been defined consisting of a maritime surveillance and tracking radar system, capable of producing range profiles and ISAR imagery of ships, an advanced infrared camera and a laser range profiler. For this suite we have developed a multi-sensor classification procedure, which is used to evaluate the capabilities for recognizing and identifying non-cooperative ships in coastal waters. We have found that the different sensors give complementary information. Each sensor has its own specific distance range in which it contributes most. A multi-sensor approach reduces the number of misclassifications and reliable classification results are obtained earlier compared to a single sensor approach