Stefan Ludwig

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Quantum point contacts are narrow, one-dimensional constrictions usually patterned in a two-dimensional electron system, for example by applying voltages to local gates. The linear conductance of a point contact, when measured as function of its channel width, is quantized in units of GQ = 2e(2)/h, where e is the electron charge and h is Planck's constant.(More)
The increasing functional integrity of the organism during fetal maturation is connected with increasing complex internal coordination. We hypothesize that time scales of complexity and dynamics of heart rate patterns reflect the increasing inter-dependencies within the fetal organism during its prenatal development. We investigated multi-scale complexity,(More)
Islet transplantation is a feasible therapeutic alternative for metabolically labile patients with type 1 diabetes. The primary therapeutic target is stable glycemic control and prevention of complications associated with diabetes by reconstitution of endogenous insulin secretion. However, critical shortage of donor organs, gradual loss in graft function(More)
Decreasing feature sizes have led to an increased vulnerability of random logic to soft errors. A particle strike may cause a glitch or single event transient (SET) at the output of a gate, which in turn can propagate to a register and cause a single event upset (SEU) there. Circuit level modeling and analysis of SETs provides an attractive compromise(More)
11 On-line monitoring of properties built on regular expressions sequences 183 Katell Morin-Allory, Dominique Borrione 12 Observer-based verification using introspection 195 Abstract The verification of a design's adherence to its specification has been and still is a major problem within the EDA community. Multiple issues like completeness, consistency,(More)
The electron-nuclei (hyperfine) interaction is central to spin qubits in solid state systems. It can be a severe decoherence source but also allows dynamic access to the nuclear spin states. We study a double quantum dot exposed to an on-chip single-domain nanomagnet and show that its inhomogeneous magnetic field crucially modifies the complex nuclear spin(More)
Existing cryptographic file systems for Unix do not take into account that sensitive data must often be shared with other users, but still kept secret. By design, the only one who has access to the secret data is the person who encrypted it and therefore knows the encryption key or password. This paper presents a kernel driver for a new encrypted file(More)
Designers trying to build intuitive interaction need to identify screen elements that (potentially) distract users from reaching their goals. The analysis of cursor movements has been proposed as a scalable and low-cost approach to analyze user distraction. Previous research, however, was mainly focused on finding gaze-analogous variables in cursor tracking(More)