This study evaluates 3‐D cloud effects on the radiation budget with a combined use of active sensor cloud profiling radar/CloudSat and imager Moderate Resolution Imaging Spectroradiometer/Aqua data ...on the A‐train. An algorithm is devised for constructing 3‐D cloud fields based on satellite‐observed cloud information. The 3‐D cloud fields thus constructed are used to calculate the broadband solar and thermal radiative fluxes with a 3‐D radiative transfer code developed by the authors. The aim of this study is to investigate the effects of cloud morphology on solar radiative transfer in cloudy atmosphere. For this purpose, 3‐D cloud fields are constructed with the new satellite‐based method, to which full 3D‐RT (radiative transfer) simulations are applied. The simulated 3‐D radiation fields are then used to examine and quantify errors of existing typical plane‐parallel approximations, i.e., Plane‐Parallel Approximation, Independent Pixel Approximation and Tilted Independent Pixel Approximation. Such 3D‐RT simulations also serve to address another objective of this study, i.e., to devise an accurate approximation and to characterize the observed specific 3D‐RT effects by the cloud morphology based on knowledge of idealized 3D‐RT effects. We introduce a modified approach based on an optimum value of diffusivity factor to better approximate the radiative fluxes for arbitrary solar zenith angle determined from the results of 3‐D radiative transfer simulations to redeem the overcorrections of these approximations for large solar zenith angles (SZAs). This new approach, called Slant path Independent Pixel Approximation, is found to be better than other approximations when SZA is large for some cloud cases. Based on the SZA dependence of the errors of these approximations relative to 3‐D computations, satellite‐observed real cloud cases are found to fall into either of three types of different morphologies, i.e., isolated cloud type, upper cloud‐roughened type and lower cloud‐roughened type. Such a classification offers a novel insight into error characteristics of the approximations that are interpreted in the context of specific cloud morphology.
Key Points
An algorithm is devised for constructing 3‐D cloud fields using MODIS/Aqua and CPR/CloudSat data focusing on water clouds
Solar and infrared broadband radiative fluxes are estimated in 3‐D cloudy atmospheres by using a Monte Carlo radiative transfer code
The radiative effect of 3‐D cloud morphology is characterized
Manipulating topological spin textures is a key for exploring unprecedented emergent electromagnetic phenomena. Whereas switching control of magnetic skyrmions, e.g., the transitions between a ...skyrmion-lattice phase and conventional magnetic orders, is intensively studied towards development of future memory device concepts, transitions among spin textures with different topological orders remain largely unexplored. Here we develop a series of chiral magnets MnSi
Ge
, serving as a platform for transitions among skyrmion- and hedgehog-lattice states. By neutron scattering, Lorentz transmission electron microscopy and high-field transport measurements, we observe three different topological spin textures with variation of the lattice constant controlled by Si/Ge substitution: two-dimensional skyrmion lattice in x = 0-0.25 and two distinct three-dimensional hedgehog lattices in x = 0.3-0.6 and x = 0.7-1. The emergence of various topological spin states in the chemical-pressure-controlled materials suggests a new route for direct manipulation of the spin-texture topology by facile mechanical methods.
Magnetic skyrmions, swirling nanometric spin textures, have been attracting increasing attention by virtue of their potential applications for future memory technology and their emergent ...electromagnetism. Despite a variety of theoretical proposals oriented towards skyrmion-based electronics (that is, skyrmionics), few experiments have succeeded in creating, deleting and transferring skyrmions, and the manipulation methodologies have thus far remained limited to electric, magnetic and thermal stimuli. Here, we demonstrate a new approach for skyrmion phase control based on a mechanical stress. By continuously scanning uniaxial stress at low temperatures, we can create and annihilate a skyrmion crystal in a prototypical chiral magnet MnSi. The critical stress is merely several tens of MPa, which is easily accessible using the tip of a conventional cantilever. The present results offer a new guideline even for single skyrmion control that requires neither electric nor magnetic biases and consumes extremely little energy.
While single-shot detection of silicon spin qubits is now a laboratory routine, the need for quantum error correction in a large-scale quantum computing device demands a quantum non-demolition (QND) ...implementation. Unlike conventional counterparts, the QND spin readout imposes minimal disturbance to the probed spin polarization and can therefore be repeated to extinguish measurement errors. Here, we show that an electron spin qubit in silicon can be measured in a highly non-demolition manner by probing another electron spin in a neighboring dot Ising-coupled to the qubit spin. The high non-demolition fidelity (99% on average) enables over 20 readout repetitions of a single spin state, yielding an overall average measurement fidelity of up to 95% within 1.2 ms. We further demonstrate that our repetitive QND readout protocol can realize heralded high-fidelity (>99.6%) ground-state preparation. Our QND-based measurement and preparation, mediated by a second qubit of the same kind, will allow for a wide class of quantum information protocols with electron spins in silicon without compromising the architectural homogeneity.
We report implementation of a resonantly driven singlet-triplet spin qubit in silicon. The qubit is defined by the two-electron antiparallel spin states and universal quantum control is provided ...through a resonant drive of the exchange interaction at the qubit frequency. The qubit exhibits long T_{2}^{*} exceeding 1 μs that is limited by dephasing due to the ^{29}Si nuclei rather than charge noise thanks to the symmetric operation and a large micromagnet Zeeman field gradient. The randomized benchmarking shows 99.6% single gate fidelity which is the highest reported for singlet-triplet qubits.
In ferromagnets, an electric current generally induces a transverse Hall voltage in proportion to the internal magnetization. This effect is frequently used for the electrical readout of the spin-↑ ...and spin-↓ states. Although these properties are usually not expected in antiferromagnets, recent theoretical studies predicted that a non-coplanar antiferromagnetic order with finite scalar spin chirality—meaning a solid angle spanned by neighbouring spins—can induce a large spontaneous Hall effect even without a net magnetization or external magnetic field. This phenomenon—the spontaneous topological Hall effect—can potentially be used for the efficient electrical readout of antiferromagnetic states, but it has not been experimentally verified due to a lack of appropriate materials hosting such magnetism. Here we report the discovery of an all-in–all-out-type non-coplanar antiferromagnetic order in triangular lattice compounds CoTa3S6 and CoNb3S6. These compounds are reported to host unconventionally large spontaneous Hall effects despite their vanishingly small net magnetization, and our analysis reveals that it can be explained in terms of the topological Hall effect that originates from the fictitious magnetic field associated with scalar spin chirality. These results indicate that the scalar spin chirality mechanism offers a promising route to the realization of a giant spontaneous Hall response even in compensated antiferromagnets, and highlight intercalated van der Waals magnets as a promising quasi-two-dimensional material platform to enable various non-trivial ways of electrical reading and the possible writing of non-coplanar antiferromagnetic domains.The spontaneous topological Hall effect, combining non-coplanar antiferromagnetic order with finite scalar spin chirality in the absence of a magnetic field, is now experimentally demonstrated for the triangular lattice compounds CoTa3S6 and CoNb3S6.
Vacuum Rabi splitting is demonstrated in a GaAs double quantum dot system coupled with a coplanar waveguide resonator. The coupling strength g, the decoherence rate of the quantum dot γ, and the ...decay rate of the resonator κ are derived, assuring distinct vacuum Rabi oscillation in a strong coupling regime (g,γ,κ)≈(30,25,8.0) MHz. The magnitude of decoherence is consistently interpreted in terms of the coupling of electrons to piezoelectric acoustic phonons in GaAs.
THE EARTHCARE SATELLITE Illingworth, A. J.; Barker, H. W.; Beljaars, A. ...
Bulletin of the American Meteorological Society,
08/2015, Letnik:
96, Številka:
8
Journal Article
Recenzirano
Odprti dostop
The collective representation within global models of aerosol, cloud, precipitation, and their radiative properties remains unsatisfactory. They constitute the largest source of uncertainty in ...predictions of climatic change and hamper the ability of numerical weather prediction models to forecast high-impact weather events. The joint European Space Agency (ESA)–Japan Aerospace Exploration Agency (JAXA) Earth Clouds, Aerosol and Radiation Explorer (EarthCARE) satellite mission, scheduled for launch in 2018, will help to resolve these weaknesses by providing global profiles of cloud, aerosol, precipitation, and associated radiative properties inferred from a combination of measurements made by its collocated active and passive sensors. EarthCARE will improve our understanding of cloud and aerosol processes by extending the invaluable dataset acquired by the A-Train satellitesCloudSat, Cloud–Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO), andAqua. Specifically, EarthCARE’s cloud profiling radar, with 7 dB more sensitivity thanCloudSat, will detect more thin clouds and its Doppler capability will provide novel information on convection, precipitating ice particle, and raindrop fall speeds. EarthCARE’s 355-nm high-spectral-resolution lidar will measure directly and accurately cloud and aerosol extinction and optical depth. Combining this with backscatter and polarization information should lead to an unprecedented ability to identify aerosol type. The multispectral imager will provide a context for, and the ability to construct, the cloud and aerosol distribution in 3D domains around the narrow 2D retrieved cross section. The consistency of the retrievals will be assessed to within a target of ±10 W m−2on the (10 km)² scale by comparing the multiview broadband radiometer observations to the top-of-atmosphere fluxes estimated by 3D radiative transfer models acting on retrieved 3D domains.
Current methods of tubal patency assessment Saunders, Rhiana D; Shwayder, James M; Nakajima, Steven T
Fertility and sterility,
06/2011, Letnik:
95, Številka:
7
Journal Article
Recenzirano
Odprti dostop
OBJECTIVE: To evaluate the scientific literature on current methods of uterine cavity and tubal patency assessment. DESIGN: Review of literature and appraisal of relevant articles using MEDLINE, ...OVID, EMBASE, and Cochrane on-line databases. RESULT(S): Current pelvic imaging subfertility investigations are compared with the gold standard laparoscopy. The technical aspects, associated risks, potential advantages, and weighted utility of each screening study are discussed. A comprehensive analysis of the clinical evidence regarding the safety, tolerance, and accuracy of hysterosalpingo-contrast sonography compared with alternative screening studies and/or laparoscopy is reviewed. CONCLUSION(S): Increasing evidence supports the more recently described hysterosalpingo-contrast sonography procedure as an acceptable screening study for the subfertile patient with the potential advantage that it is a comprehensive evaluation, methodologically simple, cost effective, and time efficient.
Mutual control of the electricity and magnetism in terms of magnetic (H) and electric (E) fields, the magnetoelectric (ME) effect, offers versatile low power consumption alternatives to current data ...storage, logic gate, and spintronic devices. Despite its importance, E-field control over magnetization (M) with significant magnitude was observed only at low temperatures. Here we have successfully stabilized a simultaneously ferrimagnetic and ferroelectric phase in a Y-type hexaferrite single crystal up to 450 K, and demonstrated the reversal of large non-volatile M by E field close to room temperature. Manipulation of the magnetic domains by E field is directly visualized at room temperature by using magnetic force microscopy. The present achievement provides an important step towards the application of ME multiferroics.
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