Physical interpretation of MIMO transmissions

Information theoretical analysis has shown that the application of multiple antennas at both sides of the wireless communication link can greatly improve the capacity/throughput. Although many mathematical analyses are performed on such a system, generally referred to as a Multiple-Input Multiple-Output (MIMO) system, a physical interpretation of the MIMO principle is still lacking in literature. In this paper, a physical interpretation is presented by which it is shown that a given MIMO system is more robust in richly-scattered environments

Modeling Megathrust Earthquakes Across Scales: One‐way Coupling From Geodynamics and Seismic Cycles to Dynamic Rupture

Taking the full complexity of subduction zones into account is important for realistic modeling and hazard assessment of subduction zone seismicity and associated tsunamis. Studying seismicity requires numerical methods that span a large range of spatial and temporal scales. We present the first coupled framework that resolves subduction dynamics over millions of years and earthquake dynamics down to fractions of a second. Using a two‐dimensional geodynamic seismic cycle (SC) model, we model 4 million years of subduction followed by cycles of spontaneous megathrust events. At the initiation of one such SC event, we export the self‐consistent fault and surface geometry, fault stress and strength, and heterogeneous material properties to a dynamic rupture (DR) model. Coupling leads to spontaneous dynamic rupture nucleation, propagation, and arrest with the same spatial characteristics as in the SC model. It also results in a similar material‐dependent stress drop, although dynamic slip is significantly larger. The DR event shows a high degree of complexity, featuring various rupture styles and speeds, precursory phases, and fault reactivation. Compared to a coupled model with homogeneous material properties, accounting for realistic lithological contrasts doubles the amount of maximum slip, introduces local pulse‐like rupture episodes, and relocates the peak slip from near the downdip limit of the seismogenic zone to the updip limit. When an SC splay fault is included in the DR model, the rupture prefers the splay over the shallow megathrust, although wave reflections do activate the megathrust afterward

Earthquake Rupture on Multiple Splay Faults and Its Effect on Tsunamis

Detailed imaging of accretionary wedges reveals splay fault networks that could pose a significant tsunami hazard. However, the dynamics of multiple splay fault activation during megathrust earthquakes and the consequent effects on tsunami generation are not well understood. We use a 2-D dynamic rupture model with complex topo-bathymetry and six curved splay fault geometries constrained from realistic tectonic loading modeled by a geodynamic seismic cycle model with consistent initial stress and strength conditions. We find that all splay faults rupture coseismically. While the largest splay fault slips due to a complex rupture branching process from the megathrust, all other splay faults are activated either top down or bottom up by dynamic stress transfer induced by trapped seismic waves. We ascribe these differences to local non-optimal fault orientations and variable along-dip strength excess. Generally, rupture on splay faults is facilitated by their favorable stress orientations and low strength excess as a result of high pore-fluid pressures. The ensuing tsunami modeled with non-linear 1-D shallow water equations consists of one high-amplitude crest related to rupture on the longest splay fault and a second broader wave packet resulting from slip on the other faults. This results in two episodes of flooding and a larger run-up distance than the single long-wavelength (300 km) tsunami sourced by the megathrust-only rupture. Since splay fault activation is determined by both variable stress and strength conditions and dynamic activation, considering both tectonic and earthquake processes is relevant for understanding tsunamigenesis

Understanding the diagnostic delay in rare diseases

According to the European definition, rare diseases are life-threatening or chronically debilitating conditions that affect only 5 out of 10,000 people in the European Union. It is estimated that there are around 6000-8000 different rare diseases, affecting 6-8% of the population in the course of their lives. For the Netherlands, this means that about 1 million people are affected by a rare disease, or one in 17 people. Patients with rare diseases indicate that they often have a long and uncertain diagnostic journey behind them, while the first symptoms present in childhood in 75% of the rare diseases. In this perspective, we discuss some of the results from the research report 'Scherperzicht op diagnostischevertragingbijzeldzameaandoeningen' in which the diagnostic journey for patients with rare diseases is mapped out with figures. We also make recommendations to speed up the diagnostic process for patients with rare diseases.</p