67 research outputs found
Spin supercurrent in Josephson contacts with noncollinear ferromagnets
We present a theoretical study of the Josephson coupling of two s-wave
superconductors which are connected through a diffusive contact consisting of
noncollinear ferromagnetic domains. First, we consider a contact with two
domains with magnetization vectors misoriented by an angle . Using the
quantum circuit theory, we find that in addition to the charge supercurrent, a
spin supercurrent, which is even in and odd in , with a spin
polarization normal to the magnetization vectors flows between the domains.
Furthermore, with asymmetric insulating barriers at the interfaces of the
junction, the system may experience an antiferromagnetic-ferromagnetic phase
transition for . Secondly, we discuss the spin supercurrent in an
extended magnetic texture with multiple domainwalls. We find the
position-dependent spin supercurrent. The magnitude of the spin supercurrent
strongly depends on the phase difference between the superconductors and the
number of domain walls. Our results demonstrate the possibility to couple the
superconducting phase to the magnetization dynamics.Comment: 15 pages, 7 figure
Spin-polarized supercurrents for spintronics: a review of current progress
During the past 15 years a new field has emerged, which combines
superconductivity and spintronics, with the goal to pave a way for new types of
devices for applications combining the virtues of both by offering the
possibility of long-range spin-polarized supercurrents. Such supercurrents
constitute a fruitful basis for the study of fundamental physics as they
combine macroscopic quantum coherence with microscopic exchange interactions,
spin selectivity, and spin transport. This report follows recent developments
in the controlled creation of long-range equal-spin triplet supercurrents in
ferromagnets and its contribution to spintronics. The mutual proximity-induced
modification of order in superconductor-ferromagnet hybrid structures
introduces in a natural way such evasive phenomena as triplet
superconductivity, odd-frequency pairing, Fulde-Ferrell-Larkin-Ovchinnikov
pairing, long-range equal-spin supercurrents, -Josephson junctions, as
well as long-range magnetic proximity effects. All these effects were rather
exotic before 2000, when improvements in nanofabrication and materials control
allowed for a new quality of hybrid structures. Guided by pioneering
theoretical studies, experimental progress evolved rapidly, and since 2010
triplet supercurrents are routinely produced and observed. We have entered a
new stage of studying new phases of matter previously out of our reach, and of
merging the hitherto disparate fields of superconductivity and spintronics to a
new research direction: super-spintronics.Comment: 95 pages, 23 Figures; published version with minor typos corrected
and few references adde
25th Annual Computational Neuroscience Meeting: CNS-2016
Abstracts of the 25th Annual Computational Neuroscience
Meeting: CNS-2016
Seogwipo City, Jeju-do, South Korea. 2–7 July 201
25th annual computational neuroscience meeting: CNS-2016
The same neuron may play different functional roles in the neural circuits to which it belongs. For example, neurons in the Tritonia pedal ganglia may participate in variable phases of the swim motor rhythms [1]. While such neuronal functional variability is likely to play a major role the delivery of the functionality of neural systems, it is difficult to study it in most nervous systems. We work on the pyloric rhythm network of the crustacean stomatogastric ganglion (STG) [2]. Typically network models of the STG treat neurons of the same functional type as a single model neuron (e.g. PD neurons), assuming the same conductance parameters for these neurons and implying their synchronous firing [3, 4]. However, simultaneous recording of PD neurons shows differences between the timings of spikes of these neurons. This may indicate functional variability of these neurons. Here we modelled separately the two PD neurons of the STG in a multi-neuron model of the pyloric network. Our neuron models comply with known correlations between conductance parameters of ionic currents. Our results reproduce the experimental finding of increasing spike time distance between spikes originating from the two model PD neurons during their synchronised burst phase. The PD neuron with the larger calcium conductance generates its spikes before the other PD neuron. Larger potassium conductance values in the follower neuron imply longer delays between spikes, see Fig. 17.Neuromodulators change the conductance parameters of neurons and maintain the ratios of these parameters [5]. Our results show that such changes may shift the individual contribution of two PD neurons to the PD-phase of the pyloric rhythm altering their functionality within this rhythm. Our work paves the way towards an accessible experimental and computational framework for the analysis of the mechanisms and impact of functional variability of neurons within the neural circuits to which they belong
Multi-facets of neutrophil extracellular trap in infectious diseases: Moving beyond immunity
peer reviewedNeutrophil extracellular traps (NETs) are networks of extracellular chromosomal DNA fibers, histones, and cytoplasmic granule proteins. The release of NET components from neutrophils is involved in the suppression of pathogen diffusion. Development of NETs around target microbes leads to disruption of the cell membrane, eventuating in kind of cell death that is called as NETosis. The very first step in the process of NETosis is activation of Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase upon signaling by innate immune receptors. Afterwards, produced Reactive oxygen species (ROS) trigger protein-arginine deiminase type 4, neutrophil elastase, and myeloperoxidase to generate decondensed chromatin and disrupted integrity of nuclear membrane. Subsequently, decondensed chromatin is mixed with several enzymes in the cytoplasm released from granules, leading to release of DNA and histones, and finally formation of NET. Several reports have indicated that NETosis might contribute to the immune responses through limiting the dissemination of microbial organisms. In this review, we discuss recent advances on the role of neutrophils, NETs, and their implications in the pathogenesis of microbial infections. Additionally, the prospective of the NET modulation as a therapeutic strategy to treat infectious diseases are clarified. © 2021 Elsevier Lt
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