A magnetic helix arises in chiral magnets with a wavelength set by the spin-orbit coupling.We show that the helimagnetic order is a nanoscale analog to liquid crystals, exhibiting topological structures and domain walls that are distinctly different from classical magnets. Using magnetic force microscopy and micromagnetic simulations, we demonstrate that -similar to cholesteric liquid crystals -three fundamental types of domain walls are realized in the helimagnet FeGe. We reveal the micromagnetic wall structure and show that they can carry a finite skyrmion charge, permitting coupling to spin currents and contributions to a topolog-arXiv:1704.06288v1 [cond-mat.str-el] 20 Apr 2017 ical Hall effect. Our study establishes a new class of magnetic nano-objects with non-trivial topology, opening the door to innovative device concepts based on helimagnetic domain walls.

Proteins of the Fanconi Anemia (FA) complementation group are required for crosslink (CL) repair in humans and their loss leads to severe pathological phenotypes. Here we characterize a homolog of the Fe-S cluster helicase FANCJ in the model plant Arabidopsis, AtFANCJB, and show that it is involved in interstrand CL repair. It acts at a presumably early step in concert with the nuclease FAN1 but independently of the nuclease AtMUS81, and is epistatic to both error-prone and error-free post-replicative repair in Arabidopsis. The simultaneous knock out of FANCJB and the Fe-S cluster helicase RTEL1 leads to induced cell death in root meristems, indicating an important role of the enzymes in replicative DNA repair. Surprisingly, we found that AtFANCJB is involved in safeguarding rDNA stability in plants. In the absence of AtRTEL1 and AtFANCJB, we detected a synergetic reduction to about one third of the original number of 45S rDNA copies. It is tempting to speculate that the detected rDNA instability might be due to deficiencies in G-quadruplex structure resolution and might thus contribute to pathological phenotypes of certain human genetic diseases.

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We are planning test experiments of fundamental symmetries based on the intrinsic properties of francium. It is expected that the laser cooling and trapping of francium will produce precision measurements. The pilot experiment using rubidium was performed with the goal of francium trapping. The ion beam generated with a francium ion source was investigated using a Wien filter. Each piece of equipment still must be studied in more detail, and the equipment should be upgraded in order to trap radioactive atoms.