202,675 research outputs found
Antibodies to Enteroviruses in Cerebrospinal Fluid of Patients with Acute Flaccid Myelitis.
Acute flaccid myelitis (AFM) has caused motor paralysis in >560 children in the United States since 2014. The temporal association of enterovirus (EV) outbreaks with increases in AFM cases and reports of fever, respiratory, or gastrointestinal illness prior to AFM in >90% of cases suggest a role for infectious agents. Cerebrospinal fluid (CSF) from 14 AFM and 5 non-AFM patients with central nervous system (CNS) diseases in 2018 were investigated by viral-capture high-throughput sequencing (VirCapSeq-VERT system). These CSF and serum samples, as well as multiple controls, were tested for antibodies to human EVs using peptide microarrays. EV RNA was confirmed in CSF from only 1 adult AFM case and 1 non-AFM case. In contrast, antibodies to EV peptides were present in CSF of 11 of 14 AFM patients (79%), significantly higher than controls, including non-AFM patients (1/5 [20%]), children with Kawasaki disease (0/10), and adults with non-AFM CNS diseases (2/11 [18%]) (P = 0.023, 0.0001, and 0.0028, respectively). Six of 14 CSF samples (43%) and 8 of 11 sera (73%) from AFM patients were immunoreactive to an EV-D68-specific peptide, whereas the three control groups were not immunoreactive in either CSF (0/5, 0/10, and 0/11; P = 0.008, 0.0003, and 0.035, respectively) or sera (0/2, 0/8, and 0/5; P = 0.139, 0.002, and 0.009, respectively).IMPORTANCE The presence in cerebrospinal fluid of antibodies to EV peptides at higher levels than non-AFM controls supports the plausibility of a link between EV infection and AFM that warrants further investigation and has the potential to lead to strategies for diagnosis and prevention of disease
Tracking the ultrafast motion of an antiferromagnetic order parameter
The unique functionalities of antiferromagnets offer promising routes to
advance information technology. Their compensated magnetic order leads to spin
resonances in the THz-regime, which suggest the possibility to coherently
control antiferromagnetic (AFM) devices orders of magnitude faster than
traditional electronics. However, the required time resolution, complex
sublattice interations and the relative inaccessibility of the AFM order
parameter pose serious challenges to studying AFM spin dynamics. Here, we
reveal the temporal evolution of an AFM order parameter directly in the time
domain. We modulate the AFM order in hexagonal YMnO by coherent
magnon excitation and track the ensuing motion of the AFM order parameter using
time-resolved optical second-harmonic generation (SHG). The dynamic symmetry
reduction by the moving order parameter allows us to separate electron dynamics
from spin dynamics. As transient symmetry reductions are common to coherent
excitations, we have a general tool for tracking the ultrafast motion of an AFM
order parameter.Comment: 5 pages, 4 figure
Pressure-induced unconventional superconductivity in the heavy-fermion antiferromagnet CeIn3: An 115In-NQR study under pressure
We report on the pressure-induced unconventional superconductivity in the
heavy-fermion antiferromagnet CeIn3 by means of nuclear-quadrupole-resonance
(NQR) studies conducted under a high pressure. The temperature and pressure
dependences of the NQR spectra have revealed a first-order quantum-phase
transition (QPT) from an AFM to PM at a critical pressure Pc=2.46 GPa. Despite
the lack of an AFM quantum critical point in the P-T phase diagram, we
highlight the fact that the unconventional SC occurs in both phases of the AFM
and PM. The nuclear spin-lattice relaxation rate 1/T1 in the AFM phase have
provided evidence for the uniformly coexisting AFM+SC phase. In the HF-PM phase
where AFM fluctuations are not developed, 1/T1 decreases without the coherence
peak just below Tc, followed by a power-law like T dependence that indicates an
unconventional SC with a line-node gap. Remarkably, Tc has a peak around Pc in
the HF-PM phase as well as in the AFM phase. In other words, an SC dome exists
with a maximum value of Tc = 230 mK around Pc, indicating that the origin of
the pressure-induced HF SC in CeIn3 is not relevant to AFM spin fluctuations
but to the emergence of the first-order QPT in CeIn3. When the AFM critical
temperature is suppressed at the termination point of the first-order QPT, Pc =
2.46 GPa, the diverging AFM spin-density fluctuations emerge at the critical
point from the AFM to PM. The results with CeIn3 leading to a new type of
quantum criticality deserve further theoretical investigations
Antiferromagnetic Skyrmion: Stability, Creation and Manipulation
Magnetic skyrmions are particle-like topological excitations in ferromagnets,
which have the topological number , and hence show the skyrmion Hall
effect (SkHE) due to the Magnus force effect originating from the topology.
Here, we propose the counterpart of the magnetic skyrmion in the
antiferromagnetic (AFM) system, that is, the AFM skyrmion, which is
topologically protected but without showing the SkHE. Two approaches for
creating the AFM skyrmion have been described based on micromagnetic lattice
simulations: (i) by injecting a vertical spin-polarized current to a nanodisk
with the AFM ground state; (ii) by converting an AFM domain-wall pair in a
nanowire junction. It is demonstrated that the AFM skyrmion, driven by the
spin-polarized current, can move straightly over long distance, benefiting from
the absence of the SkHE. Our results will open a new strategy on designing the
novel spintronic devices based on AFM materials.Comment: 6 pages, 6 figure
Purchasing Power Parity (PPP) of Australian Dollar: Do Test Procedures Matter?
This article aims to reexamine whether Australia’s real exchange rate is mean reverting in the long run by using quarterly trade weighted indices of real exchange rate data for the period of June 1970 to September 2009. We use the state of the art of several more recent econometric tests for this purpose. The empirical result shows that the non-stationarity of Australia’s real exchange rate cannot be rejected. Thus, our results support the PPP hypothesis in Australia. Our results are contradictory to those of Cuestas and Regis (2008), but conform to those of Darné and Hoarau (2007 & 2008).Purchasing power parity; Real exchange rate; Unit roots; Fractional integration
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