165 research outputs found

    Designing a fully compensated half-metallic ferrimagnet

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    Recent experimental work on Mn2RuxGa demonstrates its potential as a compensated ferrimagnetic half-metal (CFHM). Here we present a set of high-throughput ab initio density functional theory calculations and detailed experimental characterisation, that enable us to correctly describe the nominal Mn2RuxGa thin films, in particular with regard to site-disorder and defects. We then construct models that accurately capture all the key features of the Mn-Ru-Ga system, including magnetic compensation and the spin gap at the Fermi level. We find that electronic doping is neccessary, which is achieved with a Mn/Ga ratio smaller than two. Our study shows how composition and substrate-induced biaxial strain can be combined to design a ferrimagnetic half-metal with a compensation point close to room temperature

    Combined Multipoint Remote and In Situ Observations of the Asymmetric Evolution of a Fast Solar Coronal Mass Ejection

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    We present an analysis of the fast coronal mass ejection (CME) of 2012 March 7, which was imaged by both STEREO spacecraft and observed in situ by MESSENGER, Venus Express, Wind and Mars Express. Based on detected arrivals at four different positions in interplanetary space, it was possible to strongly constrain the kinematics and the shape of the ejection. Using the white-light heliospheric imagery from STEREO-A and B, we derived two different kinematical profiles for the CME by applying the novel constrained self-similar expansion method. In addition, we used a drag-based model to investigate the influence of the ambient solar wind on the CME's propagation. We found that two preceding CMEs heading in different directions disturbed the overall shape of the CME and influenced its propagation behavior. While the Venus-directed segment underwent a gradual deceleration (from ~2700 km/s at 15 R_sun to ~1500 km/s at 154 R_sun), the Earth-directed part showed an abrupt retardation below 35 R_sun (from ~1700 to ~900 km/s). After that, it was propagating with a quasi-constant speed in the wake of a preceding event. Our results highlight the importance of studies concerning the unequal evolution of CMEs. Forecasting can only be improved if conditions in the solar wind are properly taken into account and if attention is also paid to large events preceding the one being studied

    Single crystal investigation of proposed type-II Weyl semimetal CeAlGe

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    We present details of materials synthesis, crystal structure, and anisotropic magnetic properties of single crystals of CeAlGe, a proposed type-II Weyl semimetal. Single-crystal x-ray diffraction confirms that CeAlGe forms in noncentrosymmetric I41_1md space group, in line with predictions of non-trivial topology. Magnetization, specific heat and electrical transport measurements were used to confirm antiferromagnetic order below 5 K, with an estimated magnon excitation gap of Δ\Delta = 9.11 K from heat capacity and hole-like carrier density of 1.44 ×\times 1020^{20} cm3^{-3} from Hall effect measurements. The easy magnetic axis is along the [100] crystallographic direction, indicating that the moment lies in the tetragonal ab\it{ab}-plane below 7 K. A spin-flop transition to less than 1 μB\mu_B/Ce is observed to occur below 30 kOe at 1.8 K in the M(H)M(H) (Ha\bf{H}\|\bf{a}) data. Small magnetic fields of 3 kOe and 30 kOe are sufficient to suppress magnetic order when applied along the a\it{a}- and c\it{c}-axes, respectively, resulting in a complex TH\it{T-H} phase diagram for Ha\bf{H}\|\bf{a} and a simpler one for Hc\bf{H}\|\bf{c}

    Single-Crystal Investigation of the Proposed Type-II Weyl Semimetal CeAlGe

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    We present details of materials synthesis, crystal structure, and anisotropic magnetic properties of single crystals of CeAlGe, a proposed type-II Weyl semimetal. Single-crystal x-ray diffraction confirms that CeAlGe forms in a noncentrosymmetric I41md space group, in line with predictions of nontrivial topology. Magnetization, specific heat, and electrical transport measurements were used to confirm antiferromagnetic order below 5 K, with an estimated magnon excitation gap of Δ = 9.11 K from heat capacity and hole-like carrier density of 1.4 x 1020 cm-3 from Hall effect measurements. The easy magnetic axis is along the [100] crystallographic direction, indicating that the moment lies in the tetragonal ab plane below 7 K. A spin-flop transition to less than 1 μB/Ce is observed to occur below 30 kOe at 1.8 K in the M(H) (H||a) data. Small magnetic fields of 3 and 30 kOe are sufficient to suppress magnetic order when applied along the a and c axes, respectively, resulting in a complex T-H phase diagram for H||a and a simpler one for H||c

    Spin-echo and quantum versus classical critical fluctuations in TmVO4_4

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    Using spin-echo Nuclear Magnetic Resonance in the model Transverse-Field Ising system TmVO4_4, we show that low frequency quantum fluctuations at the quantum critical point have a very different effect on 51^{51}V nuclear-spins than classical low-frequency noise or fluctuations that arise at a finite temperature critical point. Spin-echos filter out the low frequency classical noise but not the quantum fluctuations. This allows us to directly visualize the quantum critical fan and demonstrate the persistence of quantum fluctuations at the critical coupling strength in TmVO4_4 to high temperatures in an experiment that remains transparent to finite temperature classical phase transitions. These results show that while dynamical decoupling schemes can be quite effective in eliminating classical noise in a qubit, a quantum critical environment may lead to rapid entanglement and decoherence.Comment: 10 pages, 5 figure

    Retreatment of Patients Nonresponsive to Pegylated Interferon and Ribavirin with Daily High-Dose Consensus Interferon

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    Background. Current treatment of chronic hepatitis C with pegylated interferon and ribavirin has the ability to eliminate viral infection in about half of the patients treated. Therapeutic options, for those with remaining chronic hepatitis, will remain limited until novel antivirals become available in the future. Consensus interferon is currently available and has demonstrated clinical efficacy with superior invitro antiviral activity, but the maximum tolerated dose is not defined. Methods. We assessed the efficacy of daily high-dose (24 ug) consensus interferon with weight-based (1000–1200 mg daily) ribavirin in HCV genotype 1-infected non-responder patients. Results. Six adverse events were documented in five patients, and the trial was terminated with no subject achieving viral clearance. Conclusions. The occurrence of serious adverse events effectively defined the upper limit of acceptable dose, while also revealing that this dose did not offer enhanced sustained viral clearance

    A pilot ASKAP survey for radio transients towards the Galactic Centre

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    We present the results of a radio transient and polarisation survey towards the Galactic Centre, conducted as part of the Australian Square Kilometre Array Pathfinder Variables and Slow Transients pilot survey. The survey region consisted of five fields covering 265deg2\sim265\,{\rm deg}^2 (350l10350^\circ\lesssim l\lesssim10^\circ, b10\vert b\vert \lesssim 10^\circ). Each field was observed for 12\,minutes, with between 7 and 9 repeats on cadences of between one day and four months. We detected eight highly variable sources and seven highly circularly-polarised sources (14 unique sources in total). Seven of these sources are known pulsars including the rotating radio transient PSR~J1739--2521 and the eclipsing pulsar PSR~J1723--2837. One of them is a low mass X-ray binary, 4U 1758--25. Three of them are coincident with optical or infrared sources and are likely to be stars. The remaining three may be related to the class of Galactic Centre Radio Transients (including a highly likely one, VAST~J173608.2--321634, that has been reported previously), although this class is not yet understood. In the coming years, we expect to detect \sim40 bursts from this kind of source with the proposed four-year VAST survey if the distribution of the source is isotropic over the Galactic fields.Comment: 17 pages, 13 figures, Accepted for publication in MNRA

    SDHDF: A new file format for spectral-domain radio astronomy data

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    Radio astronomy file formats are now required to store wide frequency bandwidths and multiple simultaneous receiver beams and must be able to account for versatile observing modes and numerous calibration strategies. The need to capture and archive high-time and high frequency-resolution data, along with the comprehensive metadata that fully describe the data, implies that a new data format and new processing software are required. This requirement is suited to a well-defined, hierarchically-structured and flexible file format. In this paper we present the Spectral-Domain Hierarchical Data Format (`SDHDF') -- a new file format for radio astronomy data, in particular for single dish or beam-formed data streams. Since 2018, SDHDF has been the primary format for data products from the spectral-line and continuum observing modes at Murriyang, the CSIRO Parkes 64-m radio telescope, and we demonstrate that this data format can also be used to store observations of pulsars and fast radio bursts.Comment: Supplementary material (SDHDF definition): https://ars.els-cdn.com/content/image/1-s2.0-S2213133724000192-mmc1.pd

    European dermatology forum - updated guidelines on the use of extracorporeal photopheresis 2020 - part 1.

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    Following the first investigational study on the use of extracorporeal photopheresis for the treatment of cutaneous T-cell lymphoma published in 1983, this technology has received continued use and further recognition for additional earlier as well as refractory forms. After the publication of the first guidelines for this technology in the JEADV in 2014, this technology has maintained additional promise in the treatment of other severe and refractory conditions in a multi-disciplinary setting. It has confirmed recognition in well-known documented conditions such as graft-versus-host disease after allogeneic bone marrow transplantation, systemic sclerosis, solid organ transplant rejection including lung, heart and liver and to a lesser extent inflammatory bowel disease. In order to further provide recognized expert practical guidelines for the use of this technology for all indications, the European Dermatology Forum (EDF) again proceeded to address these questions in the hands of the recognized experts within and outside the field of dermatology. This was done using the recognized and approved guidelines of EDF for this task. All authors had the opportunity to review each contribution as it was added. These updated 2020 guidelines provide at present the most comprehensive available expert recommendations for the use of extracorporeal photopheresis based on the available published literature and expert consensus opinion. The guidelines are divided in two parts: PART I covers cutaneous T-cell lymphoma, chronic graft-versus-host disease and acute graft-versus-host disease while PART II will cover scleroderma, solid organ transplantation, Crohn's disease, use of ECP in paediatrics practice, atopic dermatitis, type 1 diabetes, pemphigus, epidermolysis bullosa acquisita and erosive oral lichen planus
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