Influence of exoskeleton use on welding quality during a simulated welding task.

Purpose: The aim of this study is to investigate the effects of wearing exoskeletons during welding on the quality of the weld seam. Material and methods: A total of n = 15 young healthy subjects with welding experience took part in the study. The study design defines a 1-hr workflow that abstracts welding and grinding tasks. The sequence is based on standard DIN EN ISO 9606-1 and reproduces authentic work sequences in the constrained body positions PF-workpiece in front of the body and PE-workpiece overhead. Each subject completed the entire workflow once with and once without passive shoulder exoskeleton in a randomized order. Results: The evaluation shows that the use of passive shoulder exoskeletons has a significant influence (p = .006 for Position PF; p = .029 for Position PE) on the welding parameter travel speed which significantly influences the quality of the weld seam. The quality scale (by the used augmented reality (AR) welding simulator) of the travel speed, which significantly determines the permissibility of the weld, increases by 5.80% in the constrained body position PF and by 28.87% in the constrained body position PE when using an exoskeleton. Discussion and conclusion: The score of the welding parameter travel speed, which is essential for the permissibility of the seam, shows a statistically significant increase when an assistance system is used. Further research during real welding with exoskeletons could be based on the setup and workflow of this study.

The DNA-binding protein HTa from Thermoplasma acidophilum is an archaeal histone analog.

Histones are a principal constituent of chromatin in eukaryotes and fundamental to our understanding of eukaryotic gene regulation. In archaea, histones are widespread but not universal: several lineages have lost histone genes. What prompted or facilitated these losses and how archaea without histones organize their chromatin remains largely unknown. Here, we elucidate primary chromatin architecture in an archaeon without histones, Thermoplasma acidophilum, which harbors a HU family protein (HTa) that protects part of the genome from micrococcal nuclease digestion. Charting HTa-based chromatin architecture in vitro, in vivo and in an HTa-expressing E. coli strain, we present evidence that HTa is an archaeal histone analog. HTa preferentially binds to GC-rich sequences, exhibits invariant positioning throughout the growth cycle, and shows archaeal histone-like oligomerization behavior. Our results suggest that HTa, a DNA-binding protein of bacterial origin, has converged onto an architectural role filled by histones in other archaea.

The genetic basis and evolution of red blood cell sickling in deer.

Crescent-shaped red blood cells, the hallmark of sickle-cell disease, present a striking departure from the biconcave disc shape normally found in mammals. Characterized by increased mechanical fragility, sickled cells promote haemolytic anaemia and vaso-occlusions and contribute directly to disease in humans. Remarkably, a similar sickle-shaped morphology has been observed in erythrocytes from several deer species, without obvious pathological consequences. The genetic basis of erythrocyte sickling in deer, however, remains unknown. Here, we determine the sequences of human ß-globin orthologues in 15 deer species and use protein structural modelling to identify a sickling mechanism distinct from the human disease, coordinated by a derived valine (E22V) that is unique to sickling deer. Evidence for long-term maintenance of a trans-species sickling/non-sickling polymorphism suggests that sickling in deer is adaptive. Our results have implications for understanding the ecological regimes and molecular architectures that have promoted convergent evolution of sickling erythrocytes across vertebrates.