Publications by authors named "M Simson"

A 71-year-old man with history of coronary artery disease status post coronary artery bypass grafting (CABG) in 1999 (left internal mammary artery-left anterior descending, saphenous venous graft [SVG]-diagonal, and SVG-right coronary artery [RCA], ascending aorta aneurysm [4.8 cm], infrarenal aorta aortic aneurysm status post endovascular aortic repair, heart failure with reduced ejection fraction of 25% status post cardiac resynchronization therapy-defibrillator) presented with decompensated heart failure. He was in monomorphic ventricular tachycardia; he was cardioverted and started on amiodarone and lidocaine.

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4D-scanning transmission electron microscopy (4D-STEM) can be used to measure electric fields such as atomic fields or polarization-induced electric fields in crystal heterostructures. The paper focuses on effects occurring in 4D-STEM at interfaces, where two model systems are used: an AlN/GaN nanowire superlattice as well as a GaN/vacuum interface. Two different methods are applied: First, we employ the centre-of mass (COM) technique which uses the average momentum transfer evaluated from the intensity distribution in the diffraction pattern.

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Modern quantitative TEM methods such as the ζ-factor technique require precise knowledge of the electron beam current. To this end, a macroscopic Faraday cup was designed and constructed. It can replace the viewing screen in the projection chamber of a TEM and guarantees highly accurate measurement of the electron beam with precision only limited by the used amperemeter.

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Images acquired in transmission electron microscopes can be distorted for various reasons such as e.g. aberrations of the lenses of the imaging system or inaccuracies of the image recording system.

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Recent development in fast pixelated detector technology has allowed a two dimensional diffraction pattern to be recorded at every probe position of a two dimensional raster scan in a scanning transmission electron microscope (STEM), forming an information-rich four dimensional (4D) dataset. Electron ptychography has been shown to enable efficient coherent phase imaging of weakly scattering objects from a 4D dataset recorded using a focused electron probe, which is optimised for simultaneous incoherent Z-contrast imaging and spectroscopy in STEM. Therefore coherent phase contrast and incoherent Z-contrast imaging modes can be efficiently combined to provide a good sensitivity of both light and heavy elements at atomic resolution.

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