Parameter dependence of phase and log amplitude scintillation

Parameter dependence of phase and log amplitude scintillation - Signal statistics of spherical wave emitted by transmitter through intervening slab of irregularitie

Critical role of canonical transient receptor potential channel 7 in initiation of seizures

Status epilepticus (SE) is a life-threatening disease that has been recognized since antiquity but still causes over 50,000 deaths annually in the United States. The prevailing view on the pathophysiology of SE is that it is sustained by a loss of normal inhibitory mechanisms of neuronal activity. However, the early process leading to the initiation of SE is not well understood. Here, we show that, as seen in electroencephalograms, SE induced by the muscarinic agonist pilocarpine in mice is preceded by a specific increase in the gamma wave, and genetic ablation of canonical transient receptor potential channel (TRPC) 7 significantly reduces this pilocarpine-induced increase of gamma wave activity, preventing the occurrence of SE. At the cellular level, TRPC7 plays a critical role in the generation of spontaneous epileptiform burst firing in cornu ammonis (CA) 3 pyramidal neurons in brain slices. At the synaptic level, TRPC7 plays a significant role in the long-term potentiation at the CA3 recurrent collateral synapses and Schaffer collateral-CA1 synapses, but not at the mossy fiber-CA3 synapses. Taken together, our data suggest that epileptiform burst firing generated in the CA3 region by activity-dependent enhancement of recurrent collateral synapses may be an early event in the initiation process of SE and that TRPC7 plays a critical role in this cellular event. Our findings reveal that TRPC7 is intimately involved in the initiation of seizures both in vitro and in vivo. To our knowledge, this contribution to initiation of seizures is the first identified functional role for the TRPC7 ion channel.Fil: Phelan, K. D.. University of Arkansas for Medical Sciences; Estados UnidosFil: Shwe, U. T.. University of Arkansas for Medical Sciences; Estados UnidosFil: Abramowitz, J.. National Institute of Environmental Health Sciences; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Birnbaumer, Lutz. National Institute of Environmental Health Sciences; Estados UnidosFil: Zheng, F.. University of Arkansas for Medical Sciences; Estados Unido

Quantum oscillations and a non-trivial Berry phase in the noncentrosymmetric superconductor BiPd

We report the measurements of de Haas-van Alphen (dHvA) oscillations in the noncentrosymmetric superconductor BiPd. Several pieces of a complex multi-sheet Fermi surface are identified, including a small pocket (frequency 40 T) which is three dimensional and anisotropic. From the temperature dependence of the amplitude of the oscillations, the cyclotron effective mass is ($0.18$ $\pm$ 0.1) $m_e$. Further analysis showed a non-trivial $\pi$-Berry phase is associated with the 40 T pocket, which strongly supports the presence of topological states in bulk BiPd and may result in topological superconductivity due to the proximity coupling to other bands.Comment: 5 pages, 3 figure

High pO2 Floating Zone Crystal Growth of the Perovskite Nickelate PrNiO3

Single crystals of PrNiO3 were grown under an oxygen pressure of 295 bar using a unique high-pressure optical-image floating zone furnace. The crystals, with volume in excess of 1 mm3, were characterized structurally using single crystal and powder X-ray diffraction. Resistivity, specific heat, and magnetic susceptibility were measured, all of which evidenced an abrupt, first order metal-insulator transition (MIT) at ~130 K, in agreement with previous literature reports on polycrystalline specimens. Temperature-dependent single crystal diffraction was performed to investigate changes through the MIT. Our study demonstrates the opportunity space for high fugacity, reactive environments for single crystal growth specifically of perovskite nickelates but more generally to correlated electron oxides.Comment: 19 pages, 6 figures, Supporting Information include

Nano-magnetic droplets and implications to orbital ordering in La1-xSrxCoO3

Inelastic cold neutron scattering on LaCoO3 provided evidence for a distinct low energy excitation at 0.6 meV coincident with the thermally induced magnetic transition. Coexisting strong ferromagnetic (FM) and weaker antiferromagnetic (AFM) correlations that are dynamic follow the activation to the excited state, identified as the intermediate S=1 spin triplet. This is indicative of dynamical orbital ordering favoring the observed magnetic interactions. With hole doping as in La1-xSrxCoO3, the FM correlations between Co spins become static and isotropically distributed due to the formation of FM droplets. The correlation length and condensation temperature of these droplets increase rapidly with metallicity due to the double exchange mechanism.Comment: To appear in Phys. Rev. Let

Electrical anisotropy and coexistence of structural transitions and superconductivity in IrT e2

We report experimental investigations of the electrical transport, magnetic, and thermodynamic properties of IrTe2 single crystals. The resistivity, magnetization, and specific heat display anomalies at TS1≈283K,TS2≈167K, and Tc≈2.5K, corresponding to two structural and one superconducting phase transitions, respectively, demonstrating the coexistence of all of these transitions in high-quality stoichiometric samples. While there is little magnetic anisotropy, a large ab-plane (ρab) and c-axis (ρc) electrical resistivity ratio (ρc/ρab≈730 at T=4K) is observed. This two-dimensional (2D) electronic character is further reflected in the disparate temperature dependences of ρab and ρc, with ρab exhibiting a Fermi-liquid-like T2 dependence below ∼25K, while ρc deviates significantly from this standard metallic behavior. In contrast, the magnetization is almost isotropic and negative over a wide temperature range. This can be explained by larger diamagnetism induced by electronic structure reconstruction as probed by the Hall effect and smaller positive contribution from itinerant electrons due to a low density of states (DOS) at the Fermi level. A small electronic specific heat coefficient with γ≈1.8mJ/molK2 confirms this assertion. This implies that IrTe2 is a weakly coupled superconductor. The connection between the superconductivity and the two structural transitions is discussed