Miracle-dz/UniFAR-FTUs huggingface dataset:
Long-lived, doubly charged diatomic and triatomic molecular ions

Lifetimes of doubly charged diatomic and triatomic molecules have been measured by monitoring the decay curves of such ions in a heavy-ion storage ring. CO2+, N22+, CO22+, CS22+ and SH2+ are all found to possess long-lived components which survive for time periods greater than a few seconds. All these dications are found to be essentially stable and their ultimate destruction is due to interactions with residual gases in the ring. CO2+ possesses many more lifetime components in the millisecond range than the isoelectronic N22+ ion. Translational energy spectrometry experiments on the latter species also fail to reveal any short-lived (microsecond) components. Ab initio configuration interaction calculations have been carried out and the potential energy curve for the lowest-energy metastable state of N22+ (1 Sigma g) has been determined, along with Franck-Condon factors for vertical transitions to different vibrational levels from the ground state of neutral N2; tunnelling times of each vibrational level have been computed.
First light of engineered diffusers at the Nordic Optical Telescope reveal time variability of the optical eclipse depth of WASP-12b

We present the characterization of two engineered diffusers mounted on the 2.5-meter Nordic Optical Telescope, located at Roque de Los Muchachos, Spain. To assess the reliability and the efficiency of the diffusers, we carried out several test observations of two photometric standard stars, along with observations of one primary transit observation of TrES-3b in the red (R band), one of CoRoT-1b in the blue (B band), and three secondary eclipses of WASP-12b (V band). The achieved photometric precision is in all cases within the submillimagnitude level for exposures between 25 and 180 s. Along with a detailed analysis of the functionality of the diffusers, we add a new transit depth measurement in the blue (B band) to the already observed transmission spectrum of CoRoT-1b, disfavoring a Rayleigh slope. We also report variability of the eclipse depth of WASP-12b in the V band. For the WASP-12b secondary eclipses, we observe a secondary depth deviation of about 5σ, and a difference of 6σ and 2.5σ when compared to the values reported by other authors in a similar wavelength range determined from Hubble Space Telescope data. We further speculate about the potential physical processes or causes responsible for this observed variability.
High-performance nanowire complementary metal-semiconductor inverters

We demonstrated the construction of complementary metal-semiconductor (CMES) inverters with single n- and p-type nanowires (NWs) on the same chip. A single p-type NW was assembled by the side of an n-type NW via the electric field assembly method. n- and p-channel metal-semiconductor field-effect transistors were fabricated with n- and p-type NWs, respectively. Based on this, high-performance NW CMES NOT logic gate (inverter) was built. The NW CMES inverters have low operating voltage (≤2 V), high voltage gain (≥7), and low static power dissipation (≤0.3 nW).
Pre-allocated MAC Protocol Based on Underwater Acoustic Communication Network

The underwater acoustic channel has the characteristics of large delay and narrow bandwidth, which makes it difficult to directly apply the onshore wireless network communication protocol underwater, and the design of communication protocol that meets the characteristics of underwater acoustic communication is the focus of this study. The MAC protocol is an important part of the underwater acoustic communication network protocol, which stipulates the way nodes access the channel, which directly affects the performance of the underwater acoustic sensor network. Therefore, this paper designs a pre-allocation MAC protocol based on time slot allocation, which trains before time slot allocation through reinforcement learning and distributes the results to network nodes. Simulation results show that compared with the traditional TDMA protocol, the protocol has higher system throughput and more slot utilization, which can effectively improve the performance of underwater acoustic communication network.
Mean energy density of photogenerated magnetic fields throughout the Epoch of Reionization

Magnetic fields are ubiquitous in the Universe. They seem to be present at virtually all scales and all epochs. Yet, whether the fields on cosmological scales are of astrophysical or cosmological origin remains an open major problem. Here we focus on an astrophysical mechanism based on the photoionization of the intergalactic medium during the Epoch of Reionization. Building upon previous studies that depicted the physical mechanism around isolated sources of ionization, we present here an analytic model to estimate the level at which this mechanism contributed to the magnetization of the whole Universe, thanks to the distribution of sources, before and alongside early luminous structure formation. This model suggests that the Universe may be globally magnetized to the order of, at least, a few $10^{-20}$~G comoving (i.e. several $10^{-18}$~G during the Epoch of Reionization) by this mechanism, prior to any amplification process.
The MOSDEF Survey: The Prevalence and Properties of Galaxy-wide AGN-driven Outflows at z ∼ 2

Using observations from the first 2 yr of the MOSFIRE Deep Evolution Field (MOSDEF) survey, we study 13 active galactic nucleus (AGN) driven outflows detected from a sample of 67 X-ray, IR, and/or optically selected AGNs at z ∼ 2 . The AGNs have bolometric luminosities of ∼ 10 44 – 10 46 erg s − 1 , including both quasars and moderate-luminosity AGNs. We detect blueshifted, ionized gas outflows in the Hβ, [O iii], Hα, and/or [N ii] emission lines of 19% of the AGNs, while only 1.8% of the MOSDEF galaxies have similarly detected outflows. The outflow velocities span ∼300 to 1000 km s−1. Eight of the 13 outflows are spatially extended on similar scales to the host galaxies, with spatial extents of 2.5–11.0 kpc. Outflows are detected uniformly across the star-forming main sequence, showing little trend with the host galaxy star formation rate. Line ratio diagnostics indicate that the outflowing gas is photoionized by the AGNs. We do not find evidence for positive AGN feedback, in either our small MOSDEF sample or a much larger Sloan Digital Sky Survey sample, using the BPT diagram. Given that a galaxy with an AGN is 10 times more likely to have a detected outflow, the outflowing gas is photoionized by the AGNs, and estimates of the mass and energy outflow rates indicate that stellar feedback is insufficient to drive at least some of these outflows; they are very likely to be AGN driven. The outflows have mass-loading factors of the order of unity, suggesting that they help regulate star formation in their host galaxies, though they may be insufficient to fully quench it.
Highly Efficient Optical Pumping of Spin Defects in Silicon Carbide for Stimulated Microwave Emission

We investigate the pump efficiency of silicon vacancy-related spins in silicon carbide. For a crystal inserted into a microwave cavity with a resonance frequency of 9.4 GHz, the spin population inversion factor of 75 with the saturation optical pump power of about 350 mW is achieved at room temperature. At cryogenic temperature, the pump efficiency drastically increases, owing to an exceptionally long spin-lattice relaxation time exceeding one minute. Based on the experimental results, we find realistic conditions under which a silicon carbide maser can operate in continuous-wave mode and serve as a quantum microwave amplifier.
How to Understand Fractals and Fractal Dimension of Urban Morphology

The conventional mathematical methods are based characteristic scales, while urban form has no characteristic scale in many aspects. Urban area is a measure of scale dependence, which indicates the scale-free distribution of urban patterns. In this case, the urban description based on characteristic scales should be replaced by urban characterization based on scaling. Fractal geometry is one of powerful tools for scaling analysis of cities, thus the concept of fractal cities emerged. However, how to understand city fractals is still a pending question. By means of logic deduction and ideas from fractal theory, this paper is devoted to discussing fractals and fractal dimensions of urban landscape. The main points of this work are as follows. First, urban form can be treated as pre-fractals rather than real fractals, and fractal properties of cities are only valid within certain scaling ranges. Second, the topological dimension of city fractals based on urban area is 0, thus the minimum fractal dimension value of fractal cities is equal to or greater than 0. Third, fractal dimension of urban form is used to substitute urban area, and it is better to define city fractals in a 2-dimensional embedding space, thus the maximum fractal dimension value of urban form is 2. A conclusion can be reached that urban form can be explored as fractals within certain ranges of scales and fractal geometry can be applied to the spatial analysis of the scale-free aspects of urban morphology. Based on fractal dimension, topological dimension, and embedding space dimension, a set of fractal indexes can be constructed to characterize urban form and growth.
High-throughput investigation of tunable superconductivity in FeSe films

There is an ongoing debate about the relative importance of structural change versus doping charge carriers on the mechanism of superconductivity in Fe-based materials. Elucidating this issue is a major challenge since it would require a large number of samples where structure properties or the carrier density is systematically varied. FeSe, with its structural simplicity, is an ideal platform for addressing this question. It has been demonstrated that the superconductivity in this material can be controlled through crystal lattice tuning, as well as electronic structure manipulation. Here, we apply a high-throughput methodology to FeSe to systematically delineate the interdependence of its structural and electronic properties. Using a dual-beam pulsed laser deposition, we have generated FeSe films with a marked gradient in the superconducting transition temperature (below 2 K < Tc < 12 K) across the 1 cm width of the films. The Tc gradient films display ~ 1% continuous stretch and compression in the out-of-plane and in-plane lattice constants respectively, tracking the continuous enhancement of superconductivity. Transport and angular-resolved photoemission measurements show that the electron carrier density is intimately correlated with Tc: it increases by a factor of 6 and ultimately surpasses the roughly constant hole concentration, attributed to a modification of dxy orbital bands through the lattice modulation.
Enhancement of the irreversibility field by carbon substitution in single crystal MgB$_2$

We report the detailed study of the irreversibility field {\hirr} of single crystals of Mg(B$_{1-x}$C$_{x}$)$_2$ ($x$=0, 2, 3.5, 5 and 7%) in strong magnetic fields of up to 40 T. High sensitive torque measurements revealed that the {\hirr} is greatly enhanced by a factor of two ($\mu_{0}${\hirr}(0)$\simeq$33 T in $x$=5%) by carbon substitution compared to the pristine {\mgb} owing to a reduction in the inplane coherence length. We also observed the temperature-dependent {\hirr} anisotropy in all the carbon contents. This fact strongly suggests that the two-gap superconductivity of {\mgb} is less influenced by a small amount of carbon substitution. We discuss these results focusing on the impact of carrier doping and impurity scattering on two-gap superconductor.
Mixmaster Behavior in Inhomogeneous Cosmological Spacetimes

Numerical investigation of a class of inhomogeneous cosmological spacetimes shows evidence that at a generic point in space the evolution toward the initial singularity is asymptotically that of a spatially homogeneous spacetime with Mixmaster behavior. This supports a long-standing conjecture due to Belinskii et al. on the nature of the generic singularity in Einstein's equations.
Direct evidence of a full dipole flip during the magnetic cycle of a sun-like star

Context.The behaviour of the large-scale dipolar field, during a star’s magnetic cycle, can provide valuable insight into the stellar dynamo and associated magnetic field manifestations such as stellar winds.Aims. We investigate the temporal evolution of the dipolar field of the K dwarf 61 Cyg A using spectropolarimetric observations covering nearly one magnetic cycle equivalent to two chromospheric activity cycles.Methods. The large-scale magnetic field geometry is reconstructed using Zeeman Doppler imaging, a tomographic inversion technique. Additionally, the chromospheric activity is also monitored.Results. The observations provide an unprecedented sampling of the large-scale field over a single magnetic cycle of a star other than the Sun. Our results show that 61 Cyg A has a dominant dipolar geometry except at chromospheric activity maximum. The dipole axis migrates from the southern to the northern hemisphere during the magnetic cycle. It is located at higher latitudes at chromospheric activity cycle minimum and at middle latitudes during cycle maximum. The dipole is strongest at activity cycle minimum and much weaker at activity cycle maximum.Conclusions. The behaviour of the large-scale dipolar field during the magnetic cycle resembles the solar magnetic cycle. Our results are further confirmation that 61 Cyg A indeed has a large-scale magnetic geometry that is comparable to the Sun’s, despite being a slightly older and cooler K dwarf.
The universal scaling laws that determine the achievable resolution in different schemes for super-resolution imaging

The resolution limits of popular sub-diffraction and sub-wavelength imaging schemes are examined using a unified approach that allows rapid comparison of the relative merits and shortcomings of each technique. This is intended to clarify the often confusing and constantly growing array of super-resolution techniques. Specific techniques examined include centroid-based techniques like PALM (photo-activated localization microscopy) and STORM (stochastic optical reconstruction microscopy), structured illumination techniques like SSIM (spatially structured illumination microscopy), STED (stimulated emission depletion), and GSD (ground state depletion), coherent techniques like MRI (magnetic resonance imaging), Rabi gradients, and light shift gradients, as well as quantum-inspired multi-photon techniques. It is found that the ultimate resolution for all these techniques can be described using a simple ratio of an oscillation frequency to an effective decay rate, which can be physically interpreted as the number of oscillations that can be observed before decay (i.e. the quality factor Q of the imaging transition).
Radio Polarization from the Inner Galaxy at Arcminute Resolution

The Southern Galactic Plane Survey (SGPS) is an H I and 1.4 GHz continuum survey of the fourth quadrant of the Galaxy at arcminute resolution. We present here results on linearly polarized continuum emission from an initial 28 deg2 test region for the SGPS, consisting of 190 mosaicked pointings of the Australia Telescope Compact Array and covering the range 325. °5 < l < 332. °5, -0. °5 < b < 3. °5. Complicated extended structure is seen in linear polarization throughout the test region, almost all of which has no correlation with total intensity. We interpret the brightest regions of polarized emission as representing intrinsic structure in extended polarization, most likely originating in the Crux spiral arm at a distance of 3.5 kpc; fainter polarized structure is imposed by Faraday rotation in foreground material. Two large areas in the field are devoid of polarization. We argue that these voids are produced by foreground H II regions in which the magnetic field is disordered on scales of ~0.1-0.2 pc. We also identify a depolarized halo around the H II region RCW 94, which we suggest results from the interaction of the H II region with a surrounding molecular cloud.
Flower Recognition Based on an Improved Convolutional Neural Network MobileNetV3

To improve the traditional flower image recognition method, poor accuracy, poor generalization function and long recognition process. In this paper, we mainly propose a flower classification and identification method based on the improved MobileNetV3. In this model, MobileNetV3, a lightweight convolutional neural network, was selected for pre-training on the Oxford 102 dataset, and then the shared parameters obtained from the pre-training were passed to the model for flower identification, and the model was further fine-tuned. Compared with Resnext152, AlexNet, the results showed that the improved MobileNetV3 had the best overall learning with recognition accuracy exceeding 99%.
The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy

We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed a multi-wavelength ionizing spectral energy distribution using these observations and archival infrared data to create xstar photoionization models specific to the PG 1211+143 flux behavior during the epoch of our observations. Our analysis of the Chandra-HETGS spectra yields complex absorption lines from H-like and He-like ions of Ne, Mg, and Si, which confirm the presence of an ultra-fast outflow (UFO) with a velocity of approximately −17,300 km s−1 (outflow redshift zout ∼ −0.0561) in the rest frame of PG 1211+143. This absorber is well described by an ionization parameter and column density . This corresponds to a stable region of the absorber’s thermal stability curve, and furthermore its implied neutral hydrogen column is broadly consistent with a broad Lyα absorption line at a mean outflow velocity of approximately −16,980 km s−1 detected by our HST-COS observations. Our findings represent the first simultaneous detection of a UFO in both X-ray and UV observations. Our VLA observations provide evidence for an active jet in PG 1211+143, which may be connected to the X-ray and UV outflows; this possibility can be evaluated using very-long-baseline interferometric observations.
Superdense star in a spacetime with minimal length

In this paper, we generalize core–envelope model of superdense star to a noncommutative spacetime and study the modifications due to the existence of a minimal length, predicted by various approaches to quantum gravity. We first derive Einstein’s field equation in [Formula: see text]-deformed spacetime and use this to set up noncommutative version of core–envelope model describing superdense stars. We derive [Formula: see text]-deformed law of density variation, valid up to first-order approximation in deformation parameter and obtain radial and tangential pressures in [Formula: see text]-deformed spacetime. We also derive [Formula: see text]-deformed strong energy conditions and obtain a bound on the deformation parameter.
Voltage Tunable Plasmon Propagation in Dual Gated Bilayer Graphene

In this paper, we theoretically investigate plasmon propagation characteristics in AB and AA stacked bilayer graphene (BLG) in the presence of energy asymmetry due to an electrostatic field oriented perpendicularly to the plane of the graphene sheet. We first derive the optical conductivity of BLG using the Kubo formalism incorporating energy asymmetry and finite electron scattering. All results are obtained for room temperature (300K) operation. By solving Maxwell's equations in a dual gate device setup, we obtain the wavevector of propagating plasmon modes in the transverse electric (TE) and transverse magnetic (TM) directions at terahertz frequencies. The plasmon wavevector allows us to compare the compression factor, propagation length, and the mode confinement of TE and TM plasmon modes in bilayer and monolayer graphene sheets and also study the impact of material parameters on plasmon characteristics. Our results show that the energy asymmetry can be harnessed to increase the propagation length of TM plasmons in BLG. AA stacked BLG shows a larger increase in propagation length than AB stacked BLG; conversely, it is very insensitive to the Fermi level variations. Additionally, the dual gate structure allows independent modulation of the energy asymmetry and the Fermi level in BLG, which is advantageous for reconfiguring plasmon characteristics post device fabrication.
Photoelectric Properties of Screen-Printed Al-Doped ZnO Films

Photoelectric Properties of Screen-Printed Al-Doped ZnO Films The potential of cheap semiconductor materials in the area of solar energy use is illustrated by the example of zinc oxide (pure and Al-doped in various concentrations). Under investigation was the electric conductivity and photoelectric properties of ZnO thin films. The samples were prepared using screen-printing technique. The results of measurements point to non-linear relationships between Al concentration, photosensitivity and electrical conductivity of thin ZnO films. Optimal Al concentration for practical use of ZnO in photovoltaic devices is found to be ~ 1%. The experimental methods, technologies and results described in the paper could be used for further investigations in this area. Ar Sietspiedes Drukas Iegūto Al ZnO Kārtiņu Fotoelektriskās Īpašības Galvenais uzsvars ir likts uz cinka oksīda elektriskās vadāmības un gaismjutības regulēšanu legēšanas ceļā, kā arī plānu kārtiņu iegūšanas vienkāršošanu, izmantojot sietspiedes drukas tehnologiju. Autoru aprakstītās eksperimentālās metodes un tehnologijas sniedz plašu darbības lauku tālākiem pētījumiem šajā jomā.
Localizing the Solar Cycle Frequency Shifts in Global p-Modes

The 6.5 yr span of observations from the Global Oscillation Network Group and the Michelson Doppler Imager aboard the Solar and Heliospheric Observatory allows a detailed study of the solar cycle-related frequency shifts at the level of central frequencies and a-coefficients from individual multiplets and even of individual modes within a multiplet. We analyze such data and show that the shifts at all levels of averaging are consistent with the hypothesis that the global p-mode frequency shifts are closely related to the surface magnetic field distribution. Furthermore, the evolution of the surface magnetic flux distribution can be reconstructed by an inversion technique operating on the shifts within individual (n, l) multiplets.
Magnetization Plateaus in Spin Chains: “Haldane Gap” for Half-Integer Spins

We discuss zero-temperature quantum spin chains in a uniform magnetic field, with axial symmetry. For integer or half-integer spin, $S$, the magnetization curve can have plateaus and we argue that the magnetization per site $m$ is topologically quantized as $n(S\ensuremath{-}m)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{integer}$ at the plateaus, where $n$ is the period of the ground state. We also discuss conditions for the presence of the plateau at those quantized values. For $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}3/2$ and $m\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1/2$, we study several models and find two distinct types of massive phases at the plateau. One of them is argued to be a ``Haldane gap phase'' for half-integer $S$.