72 research outputs found
The quantum skyrmion Hall effect in f electron systems
The flow of electric current through a two-dimensional material in a magnetic
field gives rise to the family of Hall effects. The quantum versions of these
effects accommodate robust electronic edge channels and fractional charges.
Recently, the Hall effect of skyrmions, classical magnetic quasiparticles with
a quantized topological charge, has been theoretically and experimentally
reported, igniting ideas on a quantum version of this effect. To this end, we
perform dynamical mean field theory calculations on localized electrons
coupled to itinerant electrons in the presence of spin-orbit interaction
and a magnetic field. Our calculations reveal localized nano quantum skyrmions
that start moving transversally when a charge current in the itinerant
electrons is applied. The results show the time-transient build-up of the
quantum skyrmion Hall effect, accompanied by an Edelstein effect and a
magnetoelectric effect that rotate the spins. This work motivates studies about
the steady state of the quantum skyrmion Hall effect, looking for eventual
quantum skyrmion edge channels and their transport properties.Comment: 12 pages, 9 figure
Maternal TLR signaling is required for prenatal asthma protection by the nonpathogenic microbe Acinetobacter lwoffii F78
The pre- and postnatal environment may represent a window of opportunity for allergy and asthma prevention, and the hygiene hypothesis implies that microbial agents may play an important role in this regard. Using the cowshed-derived bacterium Acinetobacter lwoffii F78 together with a mouse model of experimental allergic airway inflammation, this study investigated the hygiene hypothesis, maternal (prenatal) microbial exposure, and the involvement of Toll-like receptor (TLR) signaling in prenatal protection from asthma. Maternal intranasal exposure to A. lwoffii F78 protected against the development of experimental asthma in the progeny. Maternally, A. lwoffii F78 exposure resulted in a transient increase in lung and serum proinflammatory cytokine production and up-regulation of lung TLR messenger RNA. Conversely, suppression of TLRs was observed in placental tissue. To investigate further, the functional relevance of maternal TLR signaling was tested in TLR2/3/4/7/9â/â knockout mice. The asthma-preventive effect was completely abolished in heterozygous offspring from A. lwoffii F78âtreated TLR2/3/4/7/9â/â homozygous mother mice. Furthermore, the mild local and systemic inflammatory response was also absent in these A. lwoffii F78âexposed mothers. These data establish a direct relationship between maternal bacterial exposures, functional maternal TLR signaling, and asthma protection in the progeny
Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank
9 pĂĄginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved:
the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded
signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other
chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and
Conselleria de Pesca de la Xunta de GaliciaPeer reviewe
Precursors of Majorana modes and their length-dependent energy oscillations probed at both ends of atomic Shiba chains
Isolated Majorana modes (MMs) are highly non-local quantum states with non-Abelian exchange statistics, which localize at the two ends of finite-size 1D topological superconductors of sufficient length. Experimental evidence for MMs is so far based on the detection of several key signatures: for example, a conductance peak pinned to the Fermi energy or an oscillatory peak splitting in short 1D systems when the MMs overlap. However, most of these key signatures were probed only on one of the ends of the 1D system, and firm evidence for an MM requires the simultaneous detection of all the key signatures on both ends. Here we construct short atomic spin chains on a superconductorâalso known as Shiba chainsâup to a chain length of 45âatoms using tip-assisted atom manipulation in scanning tunnelling microscopy experiments. We observe zero-energy conductance peaks localized at both ends of the chain that simultaneously split off from the Fermi energy in an oscillatory fashion after altering the chain length. By fitting the parameters of a low-energy model to the data, we find that the peaks are consistent with precursors of MMs that evolve into isolated MMs protected by an estimated topological gap of 50âÎŒeV in chains of at least 35ânm length, corresponding to 70âatoms.publishe
Priming of allergic immune responses by repeated ozone exposures in mice
SIGLEAvailable from TIB Hannover: F04B285 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung und Forschung, Berlin (Germany)DEGerman
Cellular sources of enhanced brain-derived neurotrophic factor production in a mouse model of allergic inflammation
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