Domain walls in ferromagnetic nanowires are potential building-blocks of future technologies such as racetrack memories, in which data encoded in the domain walls are transported using spin-polarised currents. However, the development of energy-efficient devices has been hampered by the high current densities needed to initiate domain wall motion. We show here that a remarkable reduction in the critical current density can be achieved for in-plane magnetised coupled domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks. The antiferromagnetic exchange coupling between the layers leads to simple Néel wall structures, imaged using photoemission electron and Lorentz transmission electron microscopy, with a width of only ~100 nm. The measured critical current density to set these walls in motion, detected using magnetotransport measurements, is 1.0 × 1011 Am−2, almost an order of magnitude lower than in a ferromagnetically coupled control sample. Theoretical modelling indicates that this is due to nonadiabatic driving of anisotropically coupled walls, a mechanism that can be used to design efficient domain-wall devices.

We have investigated the use of a Timepix detector as a method for increasing the realisable temporal resolution of a conventional 200keV transmission electron microscope (TEM). Evaluation of both single and integral mode image exposures was performed. Single exposure mode images showed that the available electron beam current became the limiting factor for timescales <100 µs. Analysis of integral mode images showed that exposures times down to 500 ns were possible but that increases in image intensity and noise occurred. The performance data obtained represents a significant performance improvement on current TEM CCD imaging detectors.

Objectives Transmission of enteric pathogens from food ingestion is an ongoing public health concern, with commensal bacteria in ruminant animal species causing human disease. Enteric pathogens Salmonella, Shigella, and Shiga toxin producing Escherichia coli (STEC) have been isolated from domesticated animals. However, the Alaskan subsistence diet relies on wild game, such as reindeer, caribou, and moose for their food supply. Research concerning enteric pathogens in wildlife has not established. Therefore, we conducted a pilot survey on moose and reindeer to determine potential enteric pathogen transfer risk. Methods Between July 2018 and January 2019, we collected 72 fecal samples from reindeer and moose migrating in Fairbanks, Anchorage, and the Matanuska Valley. Samples were cultured for enteric pathogens, including E coli 0157, using standard clinical microbial process. Phenotypic Shiga toxin production was verified by enzyme immunoassay. Results Reindeer were statistically significant for enteric pathogens when compared to moose (P < .05) Eighty percent of the reindeer population were colonized for either Shigella, Yersinia, or Shiga toxin-producing E coli, with 20% positive for multiple pathogens. Non-0157 Shiga toxin production was observed in 30% of reindeer samples, generated by a sorbitol fermenting E coli. In contrast, moose population showed a near absence of enteric pathogens with only 5% positive for Shigella. Salmonella was not identified in either animal. Conclusion Reindeer, moose, and caribou meat are prominent in the Alaskan subsistence diet. Although moose had limited enteric pathogen colonization, reindeer were significant for transmission risk, including non-0157 Shiga toxin producing E coli, which has been linked to hemolytic uremic syndrome. Isolation of a non-0157 STEC in wildlife indicates environmental colonization. Because reindeer and caribou are closely linked in diet and migration, Alaska clinical laboratories should screen for enteric pathogens, including non-0157 Shiga toxins.