Miracle-dz/UniFAR-FTUs huggingface dataset:
Ferroelectric Na0.5Bi0.5TiO3 and K0.5Bi0.5TiO3 Perovskites and Their Solid Solutions

Properties of the perovskite ferroelectrics Na0.5Bi0. 5TiO3 (NBT), K0.5Bi0. 5TiO3 (KBT) and their solid solutions are reviewed. Consideration of the NBT behavior draws attention to phenomena of the ion ordering, coexistence of several phase regions within a crystal lattice, phase transition diffusion and to a quite new phenomenon: existence of the isotropization points (temperatures) in the AFE-phase-temperature interval. In the KBT the isotropic points are absent. NBT, KBT, and their solid solutions are considered as possible useful materials for technical (in particular, for piezoelectric) applications. There are also some other A0.5 +Bi0.5B4+O3 perovskites which are interesting for future research.
Random Sequential Addition of Unoriented Squares: Breakdown of Swendsen's Conjecture.

Random sequential addition of unoriented squares onto a plane was studied by computer simulation and the results relative to the slow asymptotic approach to the jamming limit are presented. It is shown that, in contradiction with Swendsen's conjecture, the power law describing the time evolution of the surface coverage has an exponent of 1/3 (within statistical uncertainties). Methodological aspects related to the study of the asymptotic regime are emphasized.
Validation of Satellite Retrievals of Cloud Microphysics and Liquid Water Path Using Observations from FIRE.

Abstract Cloud effective radii (re) and cloud liquid water path (LWP) are derived from ISCCP spatially sampled satellite data and validated with ground-based pyranometer and microwave radiometer measurements taken on San Nicolas Island during the 1987 FIRE IFO. Values of re derived from the ISCCP data are also compared to values retrieved by a hybrid method that uses the combination of LWP derived from microwave measurement and optical thickness derived from GOES data. The results show that there is significant variability in cloud properties over a 100 km×80 km area and that the values at San Nicolas Island are not necessarily representative of the surrounding cloud field. On the other hand, even though there were large spatial variations in optical depth, the re values remained relatively constant (with σ≤2–3 µm in most cases) in the marine stratocumulus. Furthermore, values of re derived from the upper portion of the cloud generally are representative of the entire stratiform cloud. When LWP values are.
Rotational temperature of N 2 + (0,2) ions from spectrographic measurements used to infer the energy of precipitation in different auroral forms and compared with radar measurements

High resolution spectral data are used to estimate neutral temperatures at auroral heights. The data are from the High Throughput Imaging Echelle Spectrograph (HiTIES) which forms part of the Spectrographic Imaging Facility (SIF), located at Longyearbyen, Svalbard in Norway. The platform also contains photometers and a narrow angle auroral imager. Quantum molecular spectroscopy is used for modelling N 2 + 1NG (0,2), which serves as a diagnostic tool for neutral temperature and emission height variations. The theoretical spectra are convolved with the instrument function and fitted to measured rotational transition lines as a function of temperature. Measurements were made in the magnetic zenith, and along a meridian slit centred on the magnetic zenith. In the results described, the high spectral resolution of the data (0.08 nm) allows an error analysis to be performed more thoroughly than previous findings, with particular attention paid to the correct subtraction of background, and to precise wavelength calibration. Supporting measurements were made with the Svalbard Eiscat Radar (ESR). Estimates were made from both optical and radar observations of the average energy of precipitating electrons in different types of aurora. These provide confirmation that the spectral results are in agreement with the variations observed in radar profiles. In rayed aurora the neutral temperature was highest (800 K) and the energy lowest (1 keV). In a bright curling arc, the temperature at the lower border was about 550 K, corresponding to energies of 2 keV. The radar and modelling results confirm that these average values are a lower limit for an estimation of the characteristic energy. In each event the energy distribution is clearly made up of more than one spectral shape. This work emphasises the need for high time resolution as well as high spectral resolution. The present work is the first to provide rotational temperatures using a method which pays particular attention to errors in measurement and fitting, and background subtraction.
A test of the magnetospheric source of traveling convection vortices

[1] Traveling convection vortices (TCVs) are a powerful tool for probing the nature of the coupling between the solar wind, the magnetosphere, and the ionosphere. There is no reliable model of the plasma concentration in the magnetosphere, resulting in uncertainties about the factors controlling the scale size, the motion, and the numbers of field-aligned currents associated with TCV events. There is also uncertainty about whether TCV generation is current driven, voltage driven, or even driven by some more complex source. We use conjugate ground-based magnetometer data from the Greenland magnetometer chain and Antarctica to test the nature of the magnetospheric source of 18 TCV events associated with changes in the magnetopause dynamic pressure. This is achieved by statistically comparing two groups of TCV events: for one group the conjugate ionospheres are of similar conductivity, and for the other group the conductivities of the conjugate ionospheres differ by an order of magnitude. Statistically, we find that conjugate TCV events are of similar intensity in both hemispheres regardless of any difference in conductivity between the two hemispheres. We propose that this is evidence in favor of a constant current source for TCVs where the amplitude of a TCV is controlled by the local plasma concentration, the magnetic field strength, and the acceleration of the plasma.
Rotation and oblique pulsation in Kepler observations of the roAp star KIC 10483436

Photometry of KIC 10483436 was obtained continuously with 1-min exposures over a 27-d period from the Kepler satellite. The light curve shows rotational variations from surface spots with a period of 4.303 ± 0.002 d, an amplitude of about 6 mmag and eight pulsation frequencies typical of roAp stars. The high-frequency pattern consists of a quintuplet of equally spaced peaks where the frequency of the dominant central peak (68 μmag amplitude) is 1353.00 μHz (P = 12.32 min). A second set of three peaks of lower amplitude are also visible. These appear to form part of a quintuplet centred on 1511.6 μHz with the central peak and one side peak missing. The equidistant frequency spacing is 2.69 μHz, which corresponds to the 4.303 d rotation period. However, the amplitudes (12 μmag) of these peaks are too close to the detection level to allow definite identification of the multiplets. Although no spectrum is available, the character of the pulsations shows that this is a roAp star with two high-frequency modes modulated in amplitude in accordance with the oblique pulsator model. The 4.303-d variation in the light curve, which is interpreted as rotational modulation, shows harmonics as high as the 26th. These harmonics are probably a result of many patches of varying surface brightness associated with surface abundance variations characteristic of Ap stars.
Bounce‐averaged diffusion coefficients for field‐aligned chorus waves

[1] Whistler mode chorus emissions in the Earth's magnetosphere extend from the plasmapause to the boundary of trapping. Knowledge of the pitch angle and energy scattering rates is essential for accurate radiation belt modeling. Scattering rates, which are used as an input for radiation belt codes, should be evaluated dynamically and should account for the changes in plasma density, latitudinal and MLT distribution of waves, and wave spectral properties. Bounce-averaged diffusion coefficients computed with the assumption of parallel wave propagation are compared to the results of the PADIE diffusion code, which takes into account the oblique propagation of waves and higher-order resonances. The inaccuracies associated with the neglect of higher-order resonances are compared to potential errors introduced by inaccuracies in determining plasma density and the latitudinal distribution of waves. Numerical sensitivity tests show that the errors associated with the neglect of the high-order scattering are smaller than inaccuracies associated with the uncertainties in the parameters of the codes.
Control of frequency chirp in nanosecond-pulsed laser spectroscopy. 3. Spectrotemporal dynamics of an injection-seeded optical parametric oscillator

Complicated spectrotemporal processes are associated with the generation of signal and idler output pulses on a nanosecond timescale in an injection-seeded optical parametric oscillator (OPO). The mechanisms of such spectrotemporal dynamics are revealed by numerical simulation, including innovative modeling of instantaneous-frequency profiles and frequency chirp. These simulations are in satisfactory agreement with optical-heterodyne measurements of output from a nanosecond-pulsed OPO system that is based on periodically poled KTiOPO4, pumped at 532 nm by a Nd:YAG laser and injection-seeded at a signal wavelength of ∼842 nm. Frequency chirp in narrowband signal output pulses from such an OPO system has previously been observed to depend on phase mismatch between the pump, signal, and idler waves, and also on the pump-pulse energy. Our simulations accurately predict this behavior and yield realistic estimates of the frequency chirp, optical bandwidth, and spectral purity of the signal output pulse as it evolves, including effects that are not readily observed directly. This approach provides insight into instrumental conditions that facilitate continuously tunable, single-longitudinal-mode operation of such a pulsed OPO system, with optical bandwidth as close as possible to the Fourier-transform limit.
Intergrain tunneling magnetoresistance in polycrystals of the ordered double perovskite Sr 2 FeReO 6

Intergrain tunneling magnetoresistance (TMR) subsisting up to room temperature has been observed for polycrystalline ceramics of ${\mathrm{Sr}}_{2}{\mathrm{FeReO}}_{6},$ which has ordered double perovskite structure with Curie temperature above 400 K. The first-principles band calculation predicts that ${\mathrm{Sr}}_{2}{\mathrm{FeReO}}_{6}$ shows the half metallic ground state with the ferrimagnetic coupling of Fe and Re spins. The experimental results of electronic and magnetic properties are in accord with this picture. In fact, the magnitude of intergrain TMR with the magnetic field of 7 T at 4.2 and 300 K is as large as 21 and 7%, respectively, reflecting high spin polarization of carriers.
Pulsations of the auroral kilometric radiation

[1] Radio spectrograms derived from Interball-2/Polrad satellite data have been found to include the signature of a specific type of auroral kilometric radiation (AKR), characterized by 3 to 10 periodic emission intensifications. These occur at frequencies of several mHz, which are well matched with the frequency range of Pc 5 pulsations. From 61 events of pulsating AKR observed by Interball-2, 39 samples were found to pulsate at nearly the same frequency as field line resonances (FLRs) recorded simultaneously with IMAGE, the ground-based magnetometer array. The main conclusion drawn from this study is that FLRs are able to drive AKR pulsations. This is confirmed by the observed correlation between the AKR and FLR pulsation frequencies, together with analysis of the AKR source locations. The longitudinal extent of FLR structures, spanning several hours, is inferred from the large distances separating the pulsating AKR source footprints from the ground magnetometer observations. The discussion shows that FLRs are plausible sites for pulsating AKR sources, since their nonlinear evolution can lead to (1) cavity formation by the parallel electric fields of standing inertial Alfven waves, and (2) the effective transfer of electromagnetic energy from these waves into the acceleration of downflowing electrons, to energies of up to several keV during each half of a pulsation cycle.
Musielak–Orlicz Hardy Spaces Associated with Divergence Form Elliptic Operators Without Weight Assumptions

Abstract Let L be a divergence form elliptic operator with complex bounded measurable coefficients, let ω be a positive Musielak-Orlicz function on (0, ∞) of uniformly strictly critical lower-type pω ∈ (0, 1], and let ρ(x,t) = t−1/ω−1 (x,t−1 ) for x ∈ ℝ n, t ∊ (0, ∞). In this paper, we study the Musielak-Orlicz Hardy space Hω,L (ℝ n ) and its dual space BMO ρ,L * (ℝ n ), where L* denotes the adjoint operator of L in L 2 (ℝ n ). The ρ-Carleson measure characterization and the John-Nirenberg inequality for the space BMO ρ,L (ℝ n ) are also established. Finally, as applications, we show that the Riesz transform ∇L −1/2 and the Littlewood–Paley g-function gL map Hω,L (ℝ n ) continuously into L(ω).
Axial and radial growth of Ni-induced GaN nanowires

GaN nanowires (NWs) were grown on sapphire by molecular beam epitaxy. NWs form only in the presence of Ni seed particles and only under N-rich conditions. Their length increases linearly with growth time up to about 7. 5μm while their diameter remains almost constant. In contrast, a switch to Ga-rich conditions after NW formation results in radial growth, i.e., the NW diameter increases while lengthening is negligible. These results corroborate the fact that the growth of III-V NWs is governed by the accumulation of group-III atoms in the seeds, while group-V species are not preferentially incorporated at the seeds.
Possible Aerosol Effects on Lightning Activity and Structure of Hurricanes

According to observations of hurricanes located relatively close to the land, intense and persistent lightning takes place within a 250–300-km radius ring around the hurricane center, whereas the lightning activity in the eyewall takes place only during comparatively short periods usually attributed to eyewall replacement. The mechanism responsible for the formation of the maximum flash density at the tropical cyclone (TC) periphery is not well understood as yet. In this study it is hypothesized that lightning at the TC periphery arises under the influence of small continental aerosol particles (APs), which affect the microphysics and the dynamics of clouds at the TC periphery. To show that aerosols change the cloud microstructure and the dynamics to foster lightning formation, the authors use a 2D mixed-phase cloud model with spectral microphysics. It is shown that aerosols that penetrate the cloud base of maritime clouds dramatically increase the amount of supercooled water, as well as the ice contents and vertical velocities. As a result, in clouds developing in the air with high AP concentration, ice crystals, graupel, frozen drops and/or hail, and supercooled water can coexist within a single cloud zone, which allows collisions and charge separation. The simulation of possible aerosol effects on the landfalling tropical cyclone has been carried out using a 3-km-resolution Weather Research and Forecast (WRF) mesoscale model. It is shown that aerosols change the cloud microstructure in a way that permits the attribution of the observed lightning structure to the effects of continental aerosols. It is also shown that aerosols, which invigorate clouds at 250–300 km from the TC center, decrease the convection intensity in the TC center, leading to some TC weakening. The results suggest that aerosols change the intensity and the spatial distribution of precipitation in landfalling TCs and can possibly contribute to the weekly cycle of the intensity and precipitation of landfalling TCs. More detailed investigations of the TC–aerosol interaction are required.
Satellite and field studies of man's impact on the surface in arid regions

In arid regions with sandy soils, both the steppe protected from excessive anthropogenic pressures and the much brighter areas subjected to such pressures show spectral reflectivities (derived from satellite radiometric imagery) increasing with wavelength (from green to the reflective infrared). The reflectivity dip in the red, characteristic of all plants containing chlorophyll, is absent. In an ecosystem of a steppe protected from man's activities, the soil is stable and crusted. Dead plants either remain in situ or litter the surface as debris. The surface spectral reflectivities (derived from satellite imagery) can be represented as a weighted average of the soil reflectivities and the plant-debris reflectivities (which were measured in the field by a hand-held radiometer). In areas affected by man, the surface spectral reflectivities (derived from satellite imagery) virtually coincide with those of crumbled bare soil (as determined by the hand-held radiometer). There is little accumulation of organic material. In such regions, a sharp albedo increase results from anthropogenic impact (from 0.28 in the case of the protected Negev to 0.45 in the case of the adjacent, impacted Sinai). This albedo difference cannot be explained as directly due to the removal of live vegetation, but is due mainly to an accumulation of dead plants on the crusted soil in the protected steppe and the absence of such an accumulation in the impacted regions. Models of the nadir reflectivity as a function of the fractional cover by plants or plant debris (either scattered on the surface or forming a simple vertical structure) are presented and are applied to assessing the Negev vs Sinai differences and the sharp recovery (darkening) of the surface in a Sinai exclosure where anthropogenic pressures were stopped in 1974 by fencing-off the area. DOI: 10.1111/j.2153-3490.1981. tb01731.x
Intonation and text in Standard Danish

Acoustic analysis of recordings by four Standard Danish speakers reveals that each declarative sentence in a read text is associated with its own declining intonation contour, but together two or three such contours describe an overall falling slope. Individual sentence intonation contours are steeper, and demonstrate greater amounts of resetting between them, in a succession of declarative terminal sentences than in a corresponding string of coordinate main clauses. In other words, the closer relation between coordinate structures is reflected in a more coherent or less segregated intonational structure. The results are compared with other languages, and the implications for the abstract representation of Danish intonation are discussed.
High‐Resolution Wide‐Field Imaging of Star‐forming Regions in NGC 1333

BIMA Interferometer observations of dust continuum emission at 1.3 mm probe protostellar disk and envelope structures of the two brightest millimeter sources near SVS 13, from 0 . 3 to 20 . The SVS 13 ridge is the site of a small group of deeply embedded protostars in NGC 1333 that are thought to be forming solar-type stars. Powerful molecular outflows suggest these sources are still engaged in the mass accretion process and may have substantial regions surrounding the central sources undergoing infall. High-resolution 1.3 mm data in conjunction with a previously published single-dish map at 1.3 mm (R. Chini et al. 1997, AA S. Terebey, F. H. Shu, & P. Cassen 1984, ApJ, 286, 529) that defines the division between collapse and quasi-static regions in the envelope. Using a measured line width to trace the sound speed in combination with the inferred collapse radius verifies that these systems are very young, only ≈ yr old. 4 2.9 # 10 Growth of dust grains to ≈1 cm in these young protostellar disks is detected using millimeter-wave spectral index comparisons of the dust emission in the protostellar envelope and disk. These are the first observations to have high resolution and sensitivity to large-scale structures and to sample the disks and envelopes in the same system at 110 and 220 GHz (110 GHz observations from L. W. Looney, L. G. Mundy, & W. J. Welch 2000, ApJ, 529, 477). The observations demonstrate the dust-mass opacity spectral index for the compact strucb ≈ 0 tures (disks) around SVS 13A and B, whereas for the largescale envelopes, (defined by and , after b 2 b b ≈ 2 F ∝ n k ∝ n n n
The force‐free configuration of flux ropes in geomagnetotail: Cluster observations

Unambiguous knowledge of magnetic field structure and the electric current distribution is critical for understanding the origin, evolution, and related dynamic properties of magnetic flux ropes (MFRs). In this paper, a survey of 13 MFRs in the Earth's magnetotail are conducted by Cluster multipoint analysis, so that their force‐free feature, i.e., the kind of magnetic field structure satisfying J × B = 0, can be probed directly. It is showed that the selected flux ropes with the bipolar signature of the south‐north magnetic field component generally lie near the equatorial plane, as expected, and that the magnetic field gradient is rather weak near the axis center, where the curvature radius is large. The current density (up to several tens of nA/m2) reaches their maximum values as the center is approached. It is found that the stronger the current density, the smaller the angles between the magnetic field and current in MFRs. The direct observations show that only quasi force‐free structure is observed, and it tends to appear in the low plasma beta regime (in agreement with the theoretic results). The quasi force‐free region is generally found to be embedded in the central portion of the MFRs, where the current is approximately field aligned and proportional to the strength of core field. It is shown that ~60% of surveyed MFRs can be globally approximated as force free. The force‐free factor α is found to be nonconstantly varied through the quasi force‐free MFR, suggesting that the force‐free structure is nonlinear.