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.

The burden of chemotherapy-induced nausea and vomiting in children receiving hematopoietic stem cell transplantation conditioning: a prospective study.

This prospective study describes chemotherapy-induced nausea and vomiting (CINV) in children (4-18 years) receiving their first hematopoietic stem cell transplant. Emetic episodes, nausea severity (assessed using a validated, self-report nausea severity assessment tool) and antiemetic administration were documented from the start of conditioning until 24 h after the last conditioning agent was administered (acute) and for a further 7 days (delayed). Relationships between CINV control and parenteral nutrition (PN) use and acute gut GvHD (aGvHD) were explored. Fifty-nine children (4.6-17.4 years) were evaluable. Complete chemotherapy-induced vomiting (CIV; acute: 24%; delayed 22%) and chemotherapy-induced nausea (CIN; acute 7%; delayed 12%) control rates were low. Few children experienced complete CINV control (no vomiting/retching and no nausea) during the acute (5%) or delayed phases (12%). Children experiencing complete acute or delayed CIN control or complete delayed CIV control were more likely to have received: a lower proportion of their total energy requirement as PN at the end of the delayed phase (P<0.036) and PN for a shorter time (P<0.044). Low patient numbers did not permit evaluation of the association between gut aGvHD and CINV control. Effective and safe interventions aimed at improving CINV control in children are required.

[Ablation of venous valves with Nd-Yag laser--an alternative to conventional valvulotomy?]. / Venenklappenablatio mit Nd-Yag Laser--eine Alternative zur konventionellen Valvulotomie?

The careful removal of venous valves during in situ venous bypass procedures is a problem that has not been completely solved. In this experimental study, valve ablation with the Nd-Yag laser was compared with conventional valvulotomy. The investigation was performed in vitro using human vein segments with a length of 20 cm. Conventional valvulotomy was performed 16 times, 20 valves were removed with a 400 mu-fibre and 26 with the hot tip. The results were evaluated by endoscopy, light and electron microscopy. There were no vein perforations with the valvulotome and the hot tip. Endothelial damage was documented in 85% with the valvulotome and was reduced significantly to 58% with the 400 mu-fibre. With the hot tip endothelial lesions were seen in only 30%. Valve remnants were always present with the valvulotome and in no more than 15% with the hot tip. Electron microscopy supported these results in general. There was no endothelial damage in 69%.