Miracle-dz/UniFAR-FTUs huggingface dataset:
On zero frequency zonal flow and second harmonic generation by finite amplitude energetic particle induced geodesic acoustic mode

The nonlinear self-interaction of finite amplitude energetic particle induced geodesic acoustic modes (EGAMs) is investigated using the nonlinear gyrokinetic theory. It is found that both zero frequency zonal flow (ZFZF) and second harmonic can be driven by finite amplitude EGAMs, with energetic particles (EPs) playing a dominant role in the nonlinear couplings through finite orbit width effects. For ZFZF, the effects of EPs on EGAM nonlinear self-coupling dominate those of the thermal plasmas which are also present, while the second harmonic generation is only possible via finite amplitude coupling through EPs. Our findings may improve the understanding of stabilizing zonal modes and consequently drift wave turbulence.
One-component order parameter in URu2Si2 uncovered by resonant ultrasound spectroscopy and machine learning

Resonant ultrasound spectroscopy and machine learning are used to rule out many theories of hidden order in URu2Si2. The unusual correlated state that emerges in URu2Si2 below THO = 17.5 K is known as “hidden order” because even basic characteristics of the order parameter, such as its dimensionality (whether it has one component or two), are “hidden. ” We use resonant ultrasound spectroscopy to measure the symmetry-resolved elastic anomalies across THO. We observe no anomalies in the shear elastic moduli, providing strong thermodynamic evidence for a one-component order parameter. We develop a machine learning framework that reaches this conclusion directly from the raw data, even in a crystal that is too small for traditional resonant ultrasound. Our result rules out a broad class of theories of hidden order based on two-component order parameters, and constrains the nature of the fluctuations from which unconventional superconductivity emerges at lower temperature. Our machine learning framework is a powerful new tool for classifying the ubiquitous competing orders in correlated electron systems.
Plasmon-enhancement of optical near-field of metal nanoaperture surface-emitting laser

We propose a double-aperture structure to enhance the optical near-field in metal nanoaperture vertical-cavity surface-emitting lasers (VCSELs). We fabricated 850 nm GaAs VCSELs with subwavelength-sized double metal apertures closed to each other. The optical near-field localized in the metal apertures is strongly enhanced by the excitation of localized plasmon around the metal apertures. The far-field power radiated from the apertures is enhanced to be 16 times larger than that from a single aperture VCSEL. The peak power density is as large as 2.5 mW/μm2 with a spot size of 260 nm. The obtained power density is even larger than that of a conventional single-mode VCSEL without nanoapertures, which is very encouraging for use in high-density data storages.
First light for GRAVITY: Phase referencing optical interferometry for the Very Large Telescope Interferometer

GRAVITY is a new instrument to coherently combine the light of the European Southern Observatory Very Large Telescope Interferometer to form a telescope with an equivalent 130 m diameter angular resolution and a collecting area of 200 m2. The instrument comprises fiber fed integrated optics beam combination, high resolution spectroscopy, built-in beam analysis and control, near-infrared wavefront sensing, phase-tracking, dual-beam operation, and laser metrology. GRAVITY opens up to optical/infrared interferometry the techniques of phase referenced imaging and narrow angle astrometry, in many aspects following the concepts of radio interferometry. This article gives an overview of GRAVITY and reports on the performance and the first astronomical observations during commissioning in 2015/16. We demonstrate phase-tracking on stars as faint as mK ≈ 10 mag, phase-referenced interferometry of objects fainter than mK ≈ 15 mag with a limiting magnitude of mK ≈ 17 mag, minute long coherent integrations, a visibility accuracy of better than 0.25%, and spectro-differential phase and closure phase accuracy better than 0.5°, corresponding to a differential astrometric precision of better than ten microarcseconds (μas). The dual-beam astrometry, measuring the phase difference of two objects with laser metrology, is still under commissioning. First observations show residuals as low as 50 μas when following objects over several months. We illustrate the instrument performance with the observations of archetypical objects for the different instrument modes. Examples include the Galactic center supermassive black hole and its fast orbiting star S2 for phase referenced dual-beam observations and infrared wavefront sensing, the high mass X-ray binary BP Cru and the active galactic nucleus of PDS 456 for a few μas spectro-differential astrometry, the T Tauri star S CrA for a spectro-differential visibility analysis, ξ Tel and 24 Cap for high accuracy visibility observations, and η Car for interferometric imaging with GRAVITY.
Diagonals of real symmetric matrices of given spectra as a measure space

The set of diagonals of real symmetric matrices of given non negative spectrum is endowed with a measure which is obtained by the push forward of the Haar measure of the real orthogonal group. \\ We prove that the Radon Nicodym derivation of this measure with respect to the relative Euclidean measure is approximated by the coefficients of a sequence of zonal sphere polynomials corresponding with the given spectrum. There is a striking similarity between the role of the zonal sphere polynomials in the orthogonal case, and that of the Schur function in the Hermitian case. \\ Following this we obtain a combinatorial approximation for the probability of real symmetric matrix of a given spectrum to appear as the sum of two real symmetric matrices, each of a given spectrum. In addition we obtain a real orthogonal analogue to the Zuber Itzykson Harish Chandra integration formula.
Comment on "Monopole production via photon fusion and Drell-Yan processes: MadGraph implementation and perturbativity via velocity-dependent coupling and magnetic moment as novel features"

In a recent study on monopole production [Eur. Phys. J. C (2018) 78: 966], Baines et al added the potential of a magnetic dipole to the Wu-Yang potentials for the Dirac monopole and claimed that this modified Wu-Yang configuration does not affect the Dirac quantisation condition. In this comment, we argue that their claim is incorrect by showing that their modified Wu-Yang configuration leads to an infinite number of quantisation conditions. In their study, they also incorrectly identified the magnetic field of the monopole with the magnetic field of the Dirac string and its attached magnetic monopole.
Comprehensive investigation of elastic and electrical properties of Li/Ta-modified (K,Na)NbO3 lead-free piezoceramics

A full set of elastic and electrical coefficients of (K,Na)NbO3-based lead-free piezoceramics with a nominal composition of Li0.03(K0.48Na0.52)0.97(Nb0.8Ta0.2)O3 (abbreviated as KNNLT) was evaluated by the standard resonance method, and compared to those of K4CuNb8O23 doped (K0.45Na0.55)NbO3 (KNN-KCN) as well as typical Pb(Zr,Ti)O3-based piezoceramics PZT5A. The measurement of intermediate elastic stiffness and compliance coefficients of KNNLT indicated that KNNLT is elastically “softer” than KNN-KCN but “harder” than PZT5A. An extremely high piezoelectric stiffness coefficient h33 = 68.8 × 108 V/m was obtained, due to an especially low clamped dielectric constant e33S of 361. And a large longitudinal electromechanical coupling factor k33 = 57% was observed in the KNNLT system. Furthermore, the piezoelectric coefficient d33 of KNNLT was characterized via three distinctive methods: the resonance method, the Berlincourt method, and the converse piezoelectric strain measurement; while these three techniques .
The X-Ray Structure and Spectrum of the Pulsar Wind Nebula Surrounding PSR B1853+01 in W44

We present the result of a Chandra ACIS observation of the pulsar PSR B1853+01 and its associated pulsar wind nebula (PWN), embedded in the supernova remnant W44. A hard-band ACIS map cleanly distinguishes the PWN from the thermal emission of W44. The nebula is extended in the north-south direction, with an extent about half that of the radio emission. Morphological differences between the X-ray and radio images are apparent. Spectral fitting reveals a clear difference in spectral index between the hard emission from PSR B1853+01 (Γ ~ 1.4) and the extended nebula (Γ ~ 2.2). The more accurate values for the X-ray flux and spectral index are used to refine estimates for PWN parameters, including magnetic field strength, the average Lorentz factor γ of the particles in the wind, the magnetization parameter σ, and the ratio k of electrons to other particles.
Toward Informed User Decisions About Pharmacological Cognitive Enhancement

Abstract Pharmacological cognitive enhancement (PCE) refers to the use of pharmaceuticals to improve cognitive function when that use is not intended to prevent or treat disease. Those who favour a liberal approach to PCE trust users to make informed decisions about whether enhancing is in their best interest. The author argues that making informed decisions about PCE requires a nuanced risk-benefit analysis that is not accessible to many users. Presently, the PCE use of prescription medications such as methylphenidate and modafinil is widespread but most commonly happens without medical supervision. Direct and indirect barriers generate a situation where the risks and benefits of PCE are inequitably distributed; as a result, PCE is sometimes not in the user’s best interest. This is likely to also be the case for future pharmaceuticals. As a result, even if PCE pharmaceuticals were equitably distributed, its associated risks and benefits would not be. The article concludes with a discussion of the prospects of the clinical consultation on one hand, and e-health solutions on the other, in ameliorating the situation, arguing for cautious optimism.
Molecular Line Emission as a Tool for Galaxy Observations (LEGO). I. HCN as a tracer of moderate gas densities in molecular clouds and galaxies

Trends observed in galaxies, such as the Gao \& Solomon relation, suggest a linear relation between the star formation rate and the mass of dense gas available for star formation. Validation of such relations requires the establishment of reliable methods to trace the dense gas in galaxies. One frequent assumption is that the HCN ($J=1$--0) transition is unambiguously associated with gas at $\rm{}H_2$ densities $\gg{}10^4~\rm{}cm^{-3}$. If so, the mass of gas at densities $\gg{}10^4~\rm{}cm^{-3}$ could be inferred from the luminosity of this emission line, $L_{\rm{}HCN\,(1\text{--}0)}$. Here we use observations of the Orion~A molecular cloud to show that the HCN ($J=1$--0) line traces much lower densities $\sim{}10^3~\rm{}cm^{-3}$ in cold sections of this molecular cloud, corresponding to visual extinctions $A_V\approx{}6~\rm{}mag$. We also find that cold and dense gas in a cloud like Orion produces too little HCN emission to explain $L_{\rm{}HCN\,(1\text{--}0)}$ in star--forming galaxies, suggesting that galaxies might contain a hitherto unknown source of HCN emission. In our sample of molecules observed at frequencies near 100~GHz (also including $\rm{}^{12}CO$, $\rm{}^{13}CO$, $\rm{}C^{18}O$, CN, and CCH), $\rm{}N_2H^+$ is the only species clearly associated with rather dense gas.
Room temperature midinfrared electroluminescence from InSb/InAs quantum dot light emitting diodes

Self-assembled InSb submonolayer quantum dots (QDs) in an InAs matrix have been grown by molecular beam epitaxy using Sb2 and As2 fluxes. The structures exhibit bright midinfrared photoluminescence up to room temperature. Intense room temperature electroluminescence with a peak at wavelength near 3.8 μm was observed from p-i-n light emitting diode structures containing ten InSb submonolayer QD sheets inserted within the InAs active region.
Geo-Tile2Vec: A Multi-Modal and Multi-Stage Embedding Framework for Urban Analytics

Cities are very complex systems. Representing urban regions are essential for exploring, understanding, and predicting properties and features of cities. The enrichment of multi-modal urban big data has provided opportunities for researchers to enhance urban region embedding. However, existing works failed to develop an integrated pipeline that fully utilizes effective and informative data sources within geographic units. In this article, we regard a geo-tile as a geographic unit and propose a multi-modal and multi-stage representation learning framework, namely Geo-Tile2Vec, for urban analytics, especially for urban region properties identification. Specifically, in the early stage, geo-tile embeddings are firstly inferred through dynamic mobility events which are combinations of point-of-interest (POI) data and trajectory data by a Word2Vec-like model and metric learning. Then, in the latter stage, we use static street-level imagery to further enrich the embedding information by metric learning. Lastly, the framework learns distributed geo-tile embeddings for the given multi-modal data. We conduct experiments on real-world urban datasets. Four downstream tasks, i.e., main POI category classification task, main land use category classification task, restaurant average price regression task, and firm number regression task, are adopted for validating the effectiveness of the proposed framework in representing geo-tiles. Our proposed framework can significantly improve the performances of all downstream tasks. In addition, we also demonstrate that geo-tiles with similar urban region properties are geometrically closer in the vector space.
Measurements, Algorithms, and Presentations of Reality: Framing Interactions with AI-Enabled Decision Support

Bringing AI technology into clinical practice has proved challenging for system designers and medical professionals alike. The academic literature has, for example, highlighted the dangers of black-box decision-making and biased datasets. Furthermore, end-users’ ability to validate a system’s performance often disappears following the introduction of AI decision-making. We present the MAP model to understand and describe the three stages through which medical observations are interpreted and handled by AI systems. These stages are Measurement, in which information is gathered and converted into data points that can be stored and processed; Algorithm, in which computational processes transform the collected data; and Presentation, where information is returned to the user for interpretation. For each stage, we highlight possible challenges that need to be overcome to develop Human-Centred AI systems. We illuminate our MAP model through complementary case studies on colonoscopy practice and dementia diagnosis, providing examples of the challenges encountered in real-world settings. By defining Human-AI interaction across these three stages, we untangle some of the inherent complexities in designing AI technology for clinical decision-making, and aim to overcome misalignment between medical end-users and AI researchers and developers.
Next-to-next-to leading logarithmic corrections to the angular distribution and to the forward-backward asymmetries in b → X s l + l −

We present next-to-next-to leading logarithmic (NNLL) results for the double differential decay width $d\ensuremath{\Gamma}(\stackrel{\ensuremath{\rightarrow}}{b}{X}_{s}{\mathcal{l}}^{+}{\mathcal{l}}^{\ensuremath{-}})/[d\ifmmode \hat{s}\else \^{s}\fi{}d\mathrm{cos}(\ensuremath{\theta})],$ where $s=\ifmmode \hat{s}\else \^{s}\fi{}{m}_{b}^{2}$ is the invariant mass squared of the lepton pair and \ensuremath{\theta} is the angle between the momentum of the b quark and the ${\mathcal{l}}^{+},$ measured in the rest frame of the lepton pair. From these results we also derive NNLL results for the lepton forward-backward asymmetries, as these quantities are known to be very sensitive to new physics. While the principal steps in the calculation of the double differential decay width are the same as for $d\ensuremath{\Gamma}(\stackrel{\ensuremath{\rightarrow}}{b}{X}_{s}{\mathcal{l}}^{+}{\mathcal{l}}^{\ensuremath{-}})/d\ifmmode \hat{s}\else \^{s}\fi{},$ which is already known to NNLL precision, genuinely new calculations for the combined virtual and gluon bremsstrahlung corrections associated with the operators ${O}_{7},$ ${O}_{9},$ and ${O}_{10}$ are necessary. In this paper, we neglected certain other bremsstrahlung contributions, which are known to have only a small impact on $d\ensuremath{\Gamma}(\stackrel{\ensuremath{\rightarrow}}{b}{X}_{s}{\mathcal{l}}^{+}{\mathcal{l}}^{\ensuremath{-}})/d\ifmmode \hat{s}\else \^{s}\fi{}. $ We find that the NNLL corrections drastically reduce the renormalization scale (\ensuremath{\mu}) dependence of the forward-backward asymmetries. In particular, ${s}_{0},$ the position at which the forward-backward asymmetries vanish, is essentially free of uncertainties due to the renormalization scale at NNLL precision. We find ${s}_{0}^{\mathrm{NNLL}}=0.162\ifmmode\pm\else\textpm\fi{}0.005,$ where the error is dominated by the uncertainty in ${m}_{c}{/m}_{b}. $ This is to be compared with ${s}_{0}^{\mathrm{NLL}}=0.144\ifmmode\pm\else\textpm\fi{}0.020,$ where the error is dominated by uncertainties due to the choice of \ensuremath{\mu}.
Nucleosynthesis in Neutrino-driven Winds. II. Implications for Heavy Element Synthesis

During the first 20 s of its life, the enormous neutrino luminosity of a neutron star drives appreciable mass loss from its surface. This neutrino-driven wind has been previously identified as a likely site for the r-process. Qian & Woosley have derived, both analytically and numerically, the physical conditions relevant for heavy element synthesis in the wind. These conditions include the entropy (S), the electron fraction (Ye), the dynamic timescale, and the mass loss rate. Here we explore the implications of these conditions for nucleosynthesis. We find that the standard wind models derived in that paper are inadequate to make the r-process, though they do produce some rare species above the iron group. We further determine the general restrictions on the entropy, the electron fraction, and the dynamic timescale that are required to make the r-process. In particular, we derive from nuclear reaction network calculations the conditions required to give a sufficient neutron-to-seed ratio for production of the platinum peak. These conditions range from Ye ≈ 0.2 and S ≲ 100 baryon-1 for reasonable dynamic timescales of ~0.001-0.1 s, to Ye ≈ 0.4-0.495 and S ≳ 400 baryon-1 for a dynamic timescale of ~0.1 s. These conditions are also derived analytically to illustrate the physics determining the neutron-to-seed ratio.
Interstellar Pickup Ion Observations to 38 au

We provide the first direct observations of interstellar H+ and He+ pickup ions in the solar wind from 22 to 38 au. We use the Vasyliunas and Siscoe model functional form to quantify the pickup ion distributions, and while the fit parameters generally lie outside their physically expected ranges, this form allows fits that quantify variations in the pickup H+ properties with distance. By ∼20 au, the pickup ions already provide the dominant internal pressure in the solar wind. We determine the radial trends and extrapolate them to the termination shock at ∼90 au, where the pickup H+ to core solar wind density reaches ∼0.14. The pickup H+ temperature and thermal pressure increase from 22 to 38 au, indicating additional heating of the pickup ions. This produces very large extrapolated ratios of pickup H+ to solar wind temperature and pressure, and an extrapolated ratio of the pickup ion pressure to the solar wind dynamic pressure at the termination shock of ∼0.16. Such a large ratio has profound implications for moderating the termination shock and the overall outer heliospheric interaction. We also identify suprathermal tails in the H+ spectra and complex features in the He+ spectra, likely indicating variations in the pickup ion history and processing. Finally, we discover enhancements in both H+ and He+ populations just below their cutoff energies, which may be associated with enhanced local pickup. This study serves to document the release and serves as a citable reference of these pickup ion data for broad community use and analysis.
Simulating spacetime with indefinite causal order \textit{via} Rindler observers

Realization of indefinite causal order, a theoretical possibility that even causal relations between physical events can be subjected to quantum superposition, apart from its general significance for the fundamental physics research, would also enable quantum information processing that outperforms protocols in which the underlying causal structure is definite. In this paper, we propose a way to simulate specific spacetime with indefinite metric structure by exploiting the equivalence between stationary observers sitting in the vicinity of the event horizon of a Schwarzschild black hole and Rindler observers in Minkowski space. Namely, by putting a Rindler observer, who resides in causally definite Minkowski background, in a state of quantum superposition of having two different values of proper acceleration, we can simulate the experience of a stationary observer in gravitational field with indefinite metric generated by a Schwarzschild black hole in a state of quantum superposition of being at two different spatial locations with respect to the observer. In this manner, a pair of entangled Rindler observers can be used to simulate quantum communication protocols such as gravitational quantum switch or the violation of Bell's inequality for temporal order. We also discuss the possibility of experimental realization by means of optomechanical resonators.
Effect of pressure on the Raman modes of antimony

The effect of pressure on the zone-center optical phonon modes of antimony in the A7 structure has been investigated by Raman spectroscopy. The A(g) and E-g frequencies exhibit a pronounced softening with increasing pressure, the effect being related to a gradual suppression of the Peierls-like distortion of the A7 phase relative to a cubic primitive lattice. Also, both Raman modes broaden significantly under pressure. Spectra taken at low temperature indicate that the broadening is at least partly caused by phonon-phonon interactions. We also report results of ab initio frozen-phonon calculations of the A(g) and E-g mode frequencies. The presence of strong anharmonicity is clearly apparent in calculated total energy versus atom displacement relations. Pronounced nonlinearities in the force versus displacement relations are observed. Structural instabilities of the Sb A7 phase are briefly addressed in the Appendix.
Carbon nanomaterials for phototherapy

Abstract Phototherapy attracts increasing interest for broad bio-applications due to its noninvasive and highly selective nature. Owing to their good biocompatibility, unique optoelectronic properties and size/surface effects, carbon nanomaterials show great promise for phototherapy. Various carbon nanomaterials have been demonstrated as efficient phototherapy agents for a large variety of phototherapeutic applications, including cancer treatment, anti-bacteria, and Alzheimer’s disease. This review summarizes the recent progress of carbon nanomaterials for phototherapy. Current challenges and future perspectives are also discussed.