477 research outputs found
Peripheral inflammation is associated with altered substantia nigra activity and psychomotor slowing in humans
BACKGROUND: Systemic infections commonly cause sickness symptoms including psychomotor retardation. Inflammatory cytokines released during the innate immune response are implicated in the communication of peripheral inflammatory signals to the brain.
METHODS: We used functional magnetic resonance brain imaging (fMRI) to investigate neural effects of peripheral inflammation following typhoid vaccination in 16 healthy men, using a double-blind, randomized, crossover-controlled design.
RESULTS: Vaccination had no global effect on neurovascular coupling but markedly perturbed neural reactivity within substantia nigra during low-level visual stimulation. During a cognitive task, individuals in whom typhoid vaccination engendered higher levels of circulating interleukin-6 had significantly slower reaction time responses. Prolonged reaction times and larger interleukin-6 responses were associated with evoked neural activity within substantia nigra.
CONCLUSIONS: Our findings provide mechanistic insights into the interaction between inflammatio
Majorana fermions in ferromagnetic chains on the surface of bulk spin-orbit coupled -wave superconductors
Majorana fermion (MF) excitations in solid state system have non-Abelian
statistics which is essential for topological quantum computation. Previous
proposals to realize MF, however, generally requires fine-tuning of parameters.
Here we explore a platform which avoids the fine-tuning problem, namely a
ferromagnetic chain deposited on the surface of a spin-orbit coupled -wave
superconductor. We show that it generically supports zero-energy topological MF
excitations near the two ends of the chain with minimal fine-tuning. Depending
on the strength of the ferromagnetic moment in the chain, the number of MFs at
each end, , can be either one or two, and should be revealed by a robust
zero-bias peak (ZBP) of height in scanning tunneling microscopy (STM)
measurements which would show strong (weak) signals at the ends (middle) of the
chain. The role of an approximate chiral symmetry which gives an integer
topological invariant to the system is discussed.Comment: 9 pages, 4 figure
- …