Nonequilibrium steady states of driven magnetic flux lines in disordered type-II superconductors

We investigate driven magnetic flux lines in layered type-II superconductors subject to various configurations of strong point or columnar pinning centers by means of a three-dimensional elastic line model and Metropolis Monte Carlo simulations. We characterize the resulting nonequilibrium steady states by means of the force-velocity / current-voltage curve, static structure factor, mean vortex radius of gyration, number of double-kink and half-loop excitations, and velocity / voltage noise spectrum. We compare the results for the above observables for randomly distributed point and columnar defects, and demonstrate that the three-dimensional flux line structures and their fluctuations lead to a remarkable variety of complex phenomena in the steady-state transport properties of bulk superconductors.Comment: 23 pages, IOP style, 18 figures include

Efficacy of a T Cell-Biased Adenovirus Vector as a Zika Virus Vaccine

Zika virus (ZIKV) is a major public health concern due to the risk of congenital Zika syndrome in developing fetuses and Guillain-Barre syndrome in adults. Currently, there are no approved vaccines available to protect against infection. Adenoviruses are safe and highly immunogenic vaccine vectors capable of inducing lasting humoral and cellular immune responses. Here, we developed two Adenovirus (Ad) vectored Zika virus vaccines by inserting a ZIKV prM-E gene expression cassette into human Ad types 4 (Ad4-prM-E) and 5 (Ad5-prM-E). Immune correlates indicate that Ad5-prM-E vaccination induces both an anti-ZIKV antibody and T-cell responses whereas Ad4-prM-E vaccination only induces a T-cell response. In a highly lethal challenge in an interferon α/β receptor knockout mice, 80% of Ad5 vaccinated animals and 33% of Ad4 vaccinated animals survived a lethal ZIKV challenge, whereas no animals in the sham vaccinated group survived. In an infection model utilizing immunocompetent C57BL/6 mice that were immunized and then treated with a blocking anti-IFNAR-1 antibody immediately before ZIKV challenge, 100% of Ad4-prM-E and Ad5-prM-E vaccinated mice survived. This indicates that Ad4-prM-E vaccination is protective without the development of detectable anti-ZIKV antibodies. The protection seen in these highly lethal mouse models demonstrate the efficacy of Ad vectored vaccines for use against ZIKV

The Sun's Preferred Longitudes and the Coupling of Magnetic Dynamo Modes

Observations show that solar activity is distributed non-axisymmetrically, concentrating at "preferred longitudes". This indicates the important role of non-axisymmetric magnetic fields in the origin of solar activity. We investigate the generation of the non-axisymmetric fields and their coupling with axisymmetric solar magnetic field. Our kinematic generation (dynamo) model operating in a sphere includes solar differential rotation, which approximates the differential rotation obtained by inversion of helioseismic data, modelled distributions of the turbulent resistivity, non-axisymmetric mean helicity, and meridional circulation in the convection zone. We find that (1) the non-axisymmetric modes are localised near the base of the convection zone, where the formation of active regions starts, and at latitudes around $30^{\circ}$; (2) the coupling of non-axisymmetric and axisymmetric modes causes the non-axisymmetric mode to follow the solar cycle; the phase relations between the modes are found. (3) The rate of rotation of the first non-axisymmetric mode is close to that determined in the interplanetary space.Comment: 22 pages, 18 figures. Accepted for publication in the Astrophysical Journa

High temperature corrosion of Cr-W alloys in simulated syngas

Search for new high temperature materials for energy applications continues. This presentation will focus on degradation of Cr alloys containing 0-30%W by weight in a flowing gas mixture containing 30%CO, 8%CO2, 20%H2, 2%CH4, 0.8%H2S, 0.02%HCl, and 40%N2 by volume at temperatures up to 1000ºC. A pseudo-cyclic test involving heating the specimens, holding them at temperature for varying periods, and cooling them to room temperature was employed. Mass change of the specimens was determined after each cycle. Corrosion scale on the specimens was characterized using SEM, WDX, and XRD. Various sulfides, oxides, carbides, and nitrides were determined in different layers of the scale

Central Bank Transparency under Model Uncertainty

This paper explores the effects of central bank transparency on the performance of optimal inflation targeting rules. I assume that both the central bank and the private sector face uncertainty about the correct model of the economy and have to learn. A transparent central bank can reduce one source of uncertainty for private agents by communicating its policy rule to the public. The paper shows that central bank transparency plays a crucial role in stabilizing the agents' learning process and expectations. By contrast, lack of transparency can lead to expectations-driven fluctuations that have destabilizing effects on the economy, even when the central bank has adopted optimal policie

Effect of different scintillator choices on the x-ray imaging performance of CMOS sensors

The ability of wafer scale Complementary Metal Oxide Semiconductor (CMOS) imagers to integrate sensing with analogue to digital conversion at the pixel level has led to their widespread appeal in a variety of imaging applications. This has led to significant improvement in speed and reduction in read-out noise in these imagers when compared to charge-coupled devices (CCDs) and amorphous silicon/selenium based flat panel imagers (FPIs). This paper compares the performance characteristics of CMOS X-ray detectors in various configurations by varying certain parameters of a typical X-ray detector such as fibre optic face plate (FOP), scintillator substrate coating, sensor pixel pitch and scintillator thickness. The evaluations were carried out using RQA5 (70 kV) radiation beam quality aimed at general radiography applications. At comparable Air Kerma values, detectors with a fibre optic plate showed an overall better DQE performance at most spatial frequencies, starting slightly lower at low frequencies then overtaking the “no-FOP” case at mid and high frequencies. The analysis of detectors with different substrate coatings for the scintillators showed comparatively higher DQE for the white-coated aluminium substrate scintillator compared to the black-coated one. The DQE comparison of detectors with and pixel pitch resulted in a higher DQE for the pixel pitch one, with the caveat that the scintillator was thick enough as to render differences in pMTF negligible. Finally, the comparison of scintillators with varying thicknesses showed that the thickest scintillator yielded the highest DQE. These characterisation studies helped in understanding the suitability of these different configurations in various general radiography application scenarios and could be of help to prospective users to determine the overall configuration that best fits their specific imaging needs

Low-Resistance Molecular Wires Propagate Spin-Polarized Currents

Spin based properties, applications, and devices are typically related to inorganic ferromagnetic materials. The development of organic materials for spintronic applications has long been encumbered by its reliance on ferromagnetic electrodes for polarized spin injection. The discovery of the chirality-induced spin selectivity (CISS) effect, in which chiral organic molecules serve as spin filters, defines a marked departure from this paradigm because it exploits soft materials, operates at ambient temperature, and eliminates the need for a magnetic electrode. To date, the CISS effect has been explored exclusively in molecular insulators. Here we combine chiral molecules, which serve as spin filters, with molecular wires that despite not being chiral, function to preserve spin polarization. Self-Assembled monolayers (SAMs) of right-handed helical (l-proline)8 (Pro8) and corresponding peptides, N-Terminal conjugated to (porphinato)zinc or meso-To-meso ethyne-bridged (porphinato)zinc structures (Pro8PZnn), were interrogated via magnetic conducting atomic force microscopy (mC-AFM), spin-dependent electrochemistry, and spin Hall devices that measure the spin polarizability that accompanies the charge polarization. These data show that chiral molecules are not required to transmit spin-polarized currents made possible by the CISS mechanism. Measured Hall voltages for Pro8PZn1-3 substantially exceed that determined for the Pro8 control and increase dramatically as the conjugation length of the achiral PZnn component increases; mC-AFM data underscore that measured spin selectivities increase with an increasing Pro8PZn1-3 N-Terminal conjugation. Because of these effects, spin-dependent electrochemical data demonstrate that spin-polarized currents, which trace their genesis to the chiral Pro8 moiety, propagate with no apparent dephasing over the augmented Pro8PZnn length scales, showing that spin currents may be transmitted over molecular distances that greatly exceed the length of the chiral moiety that makes possible the CISS effect

Satellite observations of Arctic blowing dust events >82°N

This study reports satellite evidence for the most northerly blown dust activity yet observed on Earth. A systematic inspection of high-resolution satellite imagery identified active dust events and their sources >82°N in Peary Land, Greenland. In the absence of any local weather measurements, for all observed dust activity a focus period in April 2020 with multiple dust plumes, reanalysis climate data found the majority of dust events to be associated with wind speeds exceeding a typical threshold value for blowing sand and dust uplift. Wind direction variability points to dust-raising by cold airflow down-valley winds, likely from nearby ice masses