Miracle-dz/UniFAR-FTUs huggingface dataset:
COVID-19 Sentiment Analysis Based on Tweets

In this work, based on sentiment analysis of tweets, we investigate how individuals in Italy perceived the COVID-19 outbreak and its implications in real life. We unveil the most discussed narratives on Twitter and measure how users’ interests, sentiments, and emotions have evolved over time and across the several aspects of the pandemic. Our analysis shows that while the overall sentiment is negative, Italians have shown upbeat responses to the pandemic, especially in regards to the vaccination campaign. The emotion analysis reveals that while fear progressively decreased after the first wave of the pandemic, the overall anger has remained constant but gradually turned into various narratives.
Mathematical properties of the rotational diffusion equation

An iterative scheme for the approximative solution of the Galerkin system of the linear rotational diffusion equation for the chromophore distribution in nonlinear optical polymers is formulated. Uniformly valid asymptotic steady-state solutions are obtained in terms of power series expansions in the normalized dc field and the convergence properties of the scheme are discussed. Moreover, by neglecting the effect of the ac field, it is proved by means of the Galerkin-system approach that the equilibrium solution of the rotational diffusion equation acts as a global attractor for any initial distributions. In addition, the decay towards this distribution is a purely exponential decay for small and moderate values of the dc-field strength. When the dc-field strength exceeds a certain threshold, this relaxation process is characterized as a damped oscillation.
Avoiding multiple entry arrays

In this paper we consider the problem of avoiding arrays with more than one entry per cell. An n × n array on n symbols is said to be if an n × n latin square, on the same symbols, can be found which differs from the array in every cell. Our first result is for chessboard squares with at most two entries per black cell. We show that if k 1 and C is a 4k × 4k chessboard square on symbols 1, 2, , 4k in which every black cell contains at most two symbols and every symbol appears at most once in every row and column, then C is avoidable. Our main result is for squares with at most two entries in any cell and answers a question of Hilton. If k 3240 and F is a 4k × 4k array on 1, 2,, 4k in which every cell contains at most two symbols and every symbol appears at most twice in every row and column, then F is avoidable
Dynamic model atmospheres of AGB stars - III. Effects of frequency-dependent radiative transfer

We present a new generation of model atmospheres for AGB stars which combine time-dependent dynamics and frequency-dependent radiative transfer. This allows us to take both the effects of pulsation (shock waves, stellar winds) and the complex influence of molecular opacities into account. In the case of C-rich stars, the models also include a self-consistent time-dependent description of dust formation. We investigate the influence of frequency-dependent radiative transfer on the energy and momentum balance of the atmosphere and compare our new models to existing grey dynamical models as well as to classical hydrostatic model atmospheres. We stress the importance of non-grey radiative transfer for obtaining realistic density-temperature structures even in highly dynamical models, discussing both the resulting observable properties and the wind characteristics. Presenting synthetic spectra, we argue that the current dynamical models represent an important step in a process leading from a qualitative to a quantitative description of atmospheres and winds of pulsating AGB stars.
Detection of a fast, intense and unusual gamma-ray transient.

An unusual transient pulse of greater than approximately 50 keV photons was detected on March 5, 1979 by the gamma-ray burst sensor network using nine space probes and satellites. Its characteristics are unlike those of the known variety of gamma-ray bursts and therefore suggest that it was formed either by a completely different origin species or in a very different manner. In a companion Letter it is identified with the LMC supernova remnant N49.
Simple Pixel Structure Using Video Data Correction Method for Nonuniform Electrical Characteristics of Polycrystalline Silicon Thin-Film Transistors and Differential Aging Phenomenon of Organic Light-Emitting Diodes

A simple pixel structure using a video data correction method is proposed to compensate for electrical characteristic variations of driving thin-film transistors (TFTs) and the degradation of organic light-emitting diodes (OLEDs) in active-matrix OLED (AMOLED) displays. The proposed method senses the electrical characteristic variations of TFTs and OLEDs and stores them in external memory. The nonuniform emission current of TFTs and the aging of OLEDs are corrected by modulating video data using the stored data. Experimental results show that the emission current error due to electrical characteristic variation of driving TFTs is in the range from -63.1 to 61.4% without compensation, but is decreased to the range from -1.9 to 1.9% with the proposed correction method. The luminance error due to the degradation of an OLED is less than 1.8% when the proposed correction method is used for a 50% degraded OLED.
The random magnetic field in the Galaxy

We analyse the rotation measures (RMs) of pulsars to study the random magnetic field in the Galaxy without using any large-scale magnetic field models. Since spatial fluctuations of the interstellar magnetic field have scales extending up to a few kiloparsecs, the random magnetic field cannot be evaluated by the analysis of residuals derived from observed RMs and those predicted by a simple large-scale field model which is fitted so as to minimize the variance. We propose the use of pairs of pulsars which are seen in almost the same directions on the sky. We obtain mean strengths of the magnetic field |B ∥| in the regions between paired pulsars from differences in their RMs and dispersion measures (DMs)
Fluctuation spectra and variances in convective turbulent boundary layers: A reevaluation of old models

Most of the existing theoretical models for statistical characteristics of turbulence in convective boundary layers are based on the similarity theory by Monin and Obukhov [Trudy Geofiz. Inst. Akad. Nauk SSSR 24(151), 163 (1954)], and its further refinements. A number of such models was recently reconsidered and partially compared with available data by Kader and Yaglom [J. Fluid Mech. 212, 637 (1990); Turbulence and Coherent Structures (Kluwer, Dordrecht, 1991), p. 387]. However, in these papers the data related to variances 〈u2〉=σ2u and 〈v2〉=σ2v of horizontal velocity components were not considered at all, and the data on horizontal velocity spectra Eu(k) and Ev(k) were used only for a restricted range of not too small wave numbers k. This is connected with findings by Kaimal et al. [Q. J. R. Meteorol. Soc. 98, 563 (1972)] and Panofsky et al. [Boundary‐Layer Meteorol. 11, 355 (1977)], who showed that the Monin–Obukhov theory cannot be applied to velocity variance σ2u and σ2v and to spectra Eu(k) and Ev(.
Wetland mapping in the Zhalong National Natural Reserve, China, using optical and radar imagery and topographical data

Abstract. Knowledge of the spatial extent of wetlands is important to a series of research questions and applications such as wetland ecosystem functioning, water management, and habitat suitability assessment. This study develops a practical digital mapping technique using an optical image of a Landsat thematic mapper (TM), Envisat advanced synthetic aperture radar (SAR) image, and topographical indices derived from topographic maps. An ensemble classifier based on classification tree procedure [random forests (RFs)] is applied to three different combinations of predictors: (1) TM imagery alone (TM-only model); (2) TM imagery plus ancillary topographical data [TM + digital terrain model (DTM)]; and (3) TM imagery, ancillary topographical data and radar imagery (TM + DTM + SAR model). Accuracy assessment results indicate that the radar and topographical variables reduce classification error of marsh. The kappa coefficients for the land cover classification increases significantly as radar imagery and ancillary topographical data are added. The per-grid cell probabilities of each land-cover types are estimated based on the RFs model making use of all available predictors. A final land-cover map is generated by defining pixels as the land-cover type with the highest probabilities. Compared with a single classification and regression tree and a conventional maximum likelihood classifier, RFs produce the highest overall accuracy (72%) with a kappa coefficient of 0.6474, and marsh wetland accuracies ranging from 81.2% to 83.33%. The current study indicates that multisource data (i.e., optical, radar, and topography) are useful in the characterization of freshwater marshes and their adjacent land-cover types. The approach developed in the current study is automated, relatively easy to implement, and could be applicable in other settings over large extents.
Evidence from Tropical Raindrop Spectra of the Origin of Rain from Stratiform versus Convective Clouds

Abstract An analysis of temporal variations in gamma parameters of raindrop spectra is presented utilizing surface-based observations from the Tropical Ocean Global Atmosphere Couple Ocean-Atmosphere Experiment. An observed dramatic change in the N0 parameter, found to occur during rainfall events with little change in rainfall rate, is suggestive of a transition from rain of convective origin to rain originating from the stratiform portion of tropical systems. An empirical stratiform-convective classification method based on N0 and R (rainfall rate) is presented. Properties of the drop size spectra from the stratiform classification are consistent with micro-physical processes occurring within an aggregation/melting layer aloft, which produces more large raindrops and fewer small to medium size raindrops than rain from the convective classification, at the same rainfall rate. The occurrence of precipitation was found to be 74% (stratiform) and 26% (convective), but total rainfall, on the other hand, was .
ABSOLUTE PROPERTIES OF THE MAIN-SEQUENCE ECLIPSING BINARY STAR GX GEMINORUM: CONSTRAINTS ON CONVECTIVE CORE OVERSHOOTING

We present 12,155 new differential photometric observations in the V filter made with the Undergraduate Research Studies in Astronomy and NF\Observatory WebScopes, as well as 33 radial velocities from spectroscopic observations of the detached, 4.04 day double-lined eclipsing binary star GX Gem. Absolute dimensions of the components are determined from these new, and also from previously published, data with high precision (less than 0.7% in the masses and radii) for the purpose of testing various aspects of theoretical modeling. We obtain 1.488 ± 0.011 solar masses and 2.327 ± 0.012 solar radii for the primary, and 1.467 ± 0.010 solar masses and 2.238 ± 0.012 solar radii for the secondary. The effective temperatures and interstellar reddening of the stars are accurately determined from the spectra, uvbyβ, and UBV photometry: 6195 ± 100 K for the primary, 6165 ± 100 K for the secondary, corresponding to spectral types of F7 and F7 V, and 0.068 mag for the color excess Eb − y. Spectral line widths give rotational velocities that are synchronous with the mean orbital motion in a circular orbit. The components of GX Gem are relatively old main-sequence stars with an age of about 2.8 billion years according to models. Because the components are located right at the end of their main-sequence evolutionary paths, we can place good limits on the convective core overshooting parameter. The lowest value of αov consistent with the observations would appear to be approximately αov = 0.18. Two different theories of tidal synchronization and circularization agree that the components should be synchronously rotating, but disagree about whether or not the orbits should be circular.
Complex media characterized by chirality and negative refractive index: analysis and applications

Inclusions embedded in conventional positive refractive index materials are used to fabricate artificial materials, with negative permittivity, permeability and negative refractive index (NRI). We consider electromagnetic wave propagation in NRI materials with chiral properties that are not negligible. To this end we initially derive explicit expressions for reflection and transmission matrices for a chiral slab. The diagonal terms of the linearly polarized reflection coefficient matrix are the familiar Fresnel reflection coefficients, and the off-diagonal, cross-polarized reflection coefficients are proportional to the chiral parameter and the product of the vertically and horizontally polarized transmission coefficients of the non-chiral host medium. The-full wave modal expansion of the fields include evanescent and propagating radiation fields, several types of lateral waves associated with the phenomena of total internal "backward" reflection as well as several different surface waves (plasmons). Using NRI materials with chiral properties it is possible to fabricate rectangular slabs that perform as lenses associated with two focal lines at the opposite side of the source. Furthermore, the backward propagating lateral waves could be used to make the chiral metamaterials perform like reflectors.
Nodal domain integration model of unsaturated two‐dimensional soil‐water flow: Development

The nodal domain integration method is applied to a two-dimensional unsaturated soil water flow problem where the solution domain is discretized into irregular triangular elements and the state variable is approximated by a spatial linear trial function within each triangular element. The resulting element matrices incorporate the well-known Galerkin finite element, subdomain, and integrated finite difference numerical statements as special cases of the nodal domain integration numerical statement.
Effect of Heat and Mass Transfer Through Diffusive Walls on Three-Dimensional Double-Diffusive Natural Convection

A three-dimensional numerical study using vorticity–vector potential formulations based on the finite-volume method has been performed to investigate double-diffusive convection in a stack of cubic enclosures submitted to horizontal gradients of temperature and concentration. The flow is driven by conditions of constant temperature and concentration imposed along the two vertical side walls of each cubic enclosure, while the horizontal walls are diffusive in heat and mass. This numerical study is conducted for fixed Prandtl, Rayleigh, and Lewis numbers, Pr = 10, Ra = 105 and Le = 10, buoyancy ratio N in the range [−2, 0], and for a range of heat and mass transfer diffusion coefficients. The results show that the effect of heat and mass diffusive walls differs between the case of thermally dominated flow and the compositionally dominated one. For thermally dominated flow, considering heat and mass diffusive walls results in a change from a structure with one inner core to a multicore structure and reduces the transverse velocity. On the other hand, for solutally dominated flow, an “inverse transition” from a multicell pattern to a unicellular one occurs, and the transverse velocity increases considerably.
Steady state cooling flow models for normal elliptical galaxies

An extensive grid of steady state cooling flow models for the hot gas in elliptical galaxies is calculated. The effects of allowing inflow of surrounding gas and varying the supernova heating rate, the mass distribution of the galaxy, the rate of stellar mass loss, and the outer boundary pressure are studied. The X-ray luminosities, spectra, and surface brightness profiles of the galaxies are computed. In all of the models, the gas density varies approximately as r exp -3/2. In the models with heavy halos, the X-ray and optical surface brightnesses are nearly proportional to one another within individual galaxies, and the temperature profiles are roughly isothermal. 48 references.
Characteristics of an all-optical parametric amplifier in a silicon microring resonator

The properties of an all-optical parametric amplifier (OPA) based on four-wave-mixing (FWM) in a silicon microring resonator (MR) side-coupled to a bus waveguide are investigated. The influences of microring structural parameters on amplification performance are analyzed in the presence of two-photon absorption (TPA) and free carrier absorption (FCA) caused by TPA. The simulation results show that, due to the field enhancement, an OPA inside an MR can achieve similar net gain with a much smaller waveguide and lower pump power compared with that based on a straight waveguide.
Non-Jamming Conditions in Multi-Contact Constrained Rigid-Body Dynamics

In this paper, we study a rigid body system of one free body (e.g., workpiece) in contact with multiple fixed bodies (e.g., locators). The contacts are unilateral. The investigation is motivated for planning the task of insertion of a workpiece in a fixture. The key issue of the problem is to determine an applied force that can move the workpiece while maintaining all existing contacts with the locators. We first analyze the kinematics of the rigid body constrained by multiple unilateral contacts. The contact constraints are classified into two categories, the configuration constraints and kinematic constraints. We then find a sufficient condition for non-jamming among the multiple contacts in the constrained rigid-body dynamics. This condition is also a necessary condition when the number of contacts is no less than four. Moreover, a method to find the applied force on the workpiece that results in sliding on all contact points is presented, based on the sufficient condition for non-jamming. Numerical examples are presented and the results of the method are compared with the results of a quasistatic method.Copyright © 2005 by ASME
Some reflections inspired by my research activity in quantum mechanics

By taking advantage of my long lasting research activity on the conceptual foundations of quantum mechanics I reconsider some of the basic problems which have been at the centre of the recent debate on this theory. Specific attention is given to topics like quantum nonlocality, the impossibility of faster than light communication and the so-called measurement or macro-objectification problem. A large part of the paper deals with the dynamical reduction program and discusses its merits and achievements, as well as its limitations. The above considerations lead me in a natural way to express my personal views on the present status of the foundational studies.
Extension of the Gauss-Markov Theorem to Include the Estimation of Random Effects

The general mixed linear model can be written y = Xa + Zb, where a is a vector of fixed effects and b is a vector of random variables. Assume that E(b) = 0 and that Var (b) = a2D with D known. Consider the estimation of 21'a + 22'j3, where 21'a is estimable and ,B is the realized, though unobservable, value of b. Among linear estimators c + r'y having E(c + r'y) _ E(21i'a + 22'b), mean squared error E(c + r'y 21'a 22'b)2 is minimized by a1'& + 22'1, where , =l DZ'VO(y X&), a' = (X'V#X)-X'V#y, and V$ is any generalized inverse of V = ZDZ' belonging to the Zyskind-Martin class. It is shown that a and ,B can be computed from the solution to any of a certain class of linear systems, and that doing so facilitates the exploitation, for computational purposes, of the kind of structure associated with ANOVA models. These results extend the Gauss-Markov theorem. The results can also be applied in a certain Bayesian setting.
Degrees of recursively saturated models

Using relativizations of results of Goncharov and Peretyat'kin on decidable homogeneous models, we prove that if M is S-saturated for some Scott set S, and F is an enumeration of S, then M has a presentation recursive in F. Applying this result we are able to classify degrees coding (i) the reducts of models of PA to addition or multiplication, (ii) internally finite initial segments and (iii) nonstandard residue fields. We also use our results to simplify Solovay's characterization of degrees coding nonstandard models of Th(N). 0. Introduction. The classic theorem of Tennenbaum [T] says that there is no recursive nonstandard model of Peano arithmetic. Indeed, if (w, e, 0) F P, and (w, E3, (D) is nonstandard, then neither e nor (D is recursive. In the above situation, (w, 3) and (w, 0) are recursively saturated, and nowadays one formulates the theorem as the statement that there are no recursive, recursively saturated models of either Presburger or Skolem arithmetic. Let us say a theory T has the Tennenbaum property if T has no recursive, recursively saturated models. Macintyre proved in [Macl] that most theories of fields have the Tennenbaum property. In this paper we look at a natural refinement of the Tennenbaum property. For any countable structure M we look at Turing degrees of presentations of M. If M F P, M nonstandard, and M is isomorphic to (w, e, 0), 0 is not the Turing degree of e, nor of 0. But given M, what are the possible degrees for e, 0? And how do these relate to the possible degrees for ( 3, 0 )? Here is a sample of results proved below: (a) the set of degrees for e equals the set of degrees for (D; (b) the set of degrees for e and (D are closed upwards; (c) if M is recursively saturated, the set of degrees for (G, 0) is the same as the set of degrees for e. These are corollaries of a very general theorem about recursively saturated models of effectively perfect theories T. If W F T, % recursively saturated, there is associated with C a canonical Scott set S. Our main theorem relates degrees of presentations of W and degrees of presentations of S, showing that the sets are mutually dense. The essential tool we use is the Goncharov-Peretyat'kin Theorem on homogeneous models [G, PI, suitably relativized. A priority argument is needed here. Received by the editors November 4, 1982. 1980 Mathematics Subject Classification. Primary 03H15; Secondary 03D45, 03C50.
UNIFORM ASYMPTOTICS FOR POLYNOMIALS ORTHOGONAL WITH RESPECT TO VARYING EXPONENTIAL WEIGHTS AND APPLICATIONS TO UNIVERSALITY QUESTIONS IN RANDOM MATRIX THEORY

We consider asymptotics for orthogonal polynomials with respect to varying exponential weights wn(x)dx = e−nV(x)dx on the line as n ∞. The potentials V are assumed to be real analytic, with sufficient growth at infinity. The principle results concern Plancherel-Rotach-type asymptotics for the orthogonal polynomials down to the axis. Using these asymptotics, we then prove universality for a variety of statistical quantities arising in the theory of random matrix models, some of which have been considered recently in [31] and also in [4]. An additional application concerns the asymptotics of the recurrence coefficients and leading coefficients for the orthonormal polynomials (see also [4]). The orthogonal polynomial problem is formulated as a Riemann-Hilbert problem following [19, 20]. The Riemann-Hilbert problem is analyzed in turn using the steepest-descent method introduced in [12] and further developed in [11, 13]. A critical role in our method is played by the equilibrium measure dμV for V as analyzed in [8]. © 1999 John Wiley & Sons, Inc.
Superresolution remote sensing image processing algorithm based on wavelet transform and interpolation

According to characteristic of image wavelet transform and interpolation, this paper proposes a remote sensing image interpolation method combining wavelet transform and interpolation algorithm, which can improve the remote sensing image resolution. Experiments show that the algorithm can properly retain abundant high frequency information in original remote sensing image. After interpolation processing and wavelet reconstruction, we can obtain a remote sensing image with higher resolution, better visual effect, higher Signal Noise Ratio (SNR), more detail information and no apparent warp. Therefore, this algorithm is an effective method of super-resolution remote sensing image processing.