Effective lifting of the topological protection of quantum spin Hall edge states by edge coupling.

The scientific interest in two-dimensional topological insulators (2D TIs) is currently shifting from a more fundamental perspective to the exploration and design of novel functionalities. Key concepts for the use of 2D TIs in spintronics are based on the topological protection and spin-momentum locking of their helical edge states. In this study we present experimental evidence that topological protection can be (partially) lifted by pairwise coupling of 2D TI edges in close proximity. Using direct wave function mapping via scanning tunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled topological edges in the 2D TI bismuthene. The latter situation is realized by natural lattice line defects and reveals distinct quasi-particle interference (QPI) patterns, identified as electronic Fabry-Pérot resonator modes. In contrast, free edges show no sign of any single-particle backscattering. These results pave the way for novel device concepts based on active control of topological protection through inter-edge hybridization for, e.g., electronic Fabry-Pérot interferometry.

[Long-term results after therapy of paraffin induced sclerosing lipogranuloma of the eyelids and the anterior orbit in three patients]. / Langzeitergebnisse nach Therapie chronischer tumoröser Lipogranulome der anterioren Orbita und der Lider bei drei Patienten.

BACKGROUND: Chronic lipogranuloma of anterior orbit and the eyelids is a rare inflammatory pseudotumor with a high tendency of recurrence. It is most commonly related to prior endonasal sinus surgery. HISTORY AND SIGNS: We report on three patients with chronic lipogranulomata who were treated at the university eye-hospital of Düsseldorf during the last 8 years. These cases are discussed individually and longterm results are presented. THERAPY AND OUTCOME: Three patients underwent endonasal surgery with postsurgical use of paraffin nasal packing prior to the occurrence of chronic lipogranulomata. Histologic findings uniformly revealed granulomatous processes but in none was there any sign of a systemic granulomatous disorder (such as Boeck's disease). Additionally, one of these three patients suffered from neuroophthalmologic impairment due to infiltration of oculomotore structures. Early surgical treatment if only for extended biopsy did result in immediate severe recurrence of the disease. No recurrence of the disease has been observed, however, if surgery was duely postponed. CONCLUSIONS: Lipogranulomata seem to be caused by postsurgical paraffin nasal packing. Early treatment seems to be unfavourable because of the high tendency of recurrence. Surgical removal of any tumor masses should be delayed therefore till granuloma formation has presumably come to an end. Any early surgery should be limited to a diagnostic biopsy if judged necessary.