Miracle-dz/UniFAR-FTUs huggingface dataset:
Why Do We Turn to Virtual Companions? A Text Mining Analysis of Replika Reviews

Many people globally experience the feeling of loneliness and struggle with its consequences. A modern way to deal with this loneliness and lack of companionship is to use empathetic and emotional conversational agents. Often referred to as virtual companions, these agents can engage in human-like conversations with their users and build relationships with them through modern artificial intelligence technologies. One established service of such virtual companions is Replika, which we investigate in this study to explore what users expect to gain from long-term interactions with virtual companions and what they tend to talk about with them. Using a text mining approach and 119,831 reviews of the Replika service, we analyze users' sentiments, emotions, and topics. Our results show that users interact with virtual companions to cope with their loneliness and, especially, to address their mental well-being. Furthermore, Replika users have a joyful and beneficial experience during long-term interaction with such virtual companions.
Instabilities in laminar separation bubbles

Abstract Wall-bounded flows, in their transition from a laminar state to turbulence, pass through a set of particular stages characterized by different physical processes. Among wall-bounded flows, separated flows have a special place because their dynamics can either be noise amplifiers or oscillators. For several years Marxen and co-workers have been studying the evolution of two- and three-dimensional perturbations in the laminar part of a laminar separation bubble. In Marxen et al. (J. Fluid Mech., vol. 728, 2013, p. 58) they study vortex formation and its evolution in laminar–turbulent transition in a forced separation bubble. By the combined use of numerical and experimental methods, different mechanisms of secondary instabilities have been highlighted: elliptic instability of vortex cores and hyperbolic instability responsible for three-dimensionality in the braid region. This work shows, for the first time in laminar separation bubbles, the first nonlinear stages of transition to turbulence of such a flow. However, since this type of flow is very sensitive to various environmental stresses, several scenarios for transition to turbulence remain to be explored.
Modeling of Evaporating Sprays Impinging onto Solid Surfaces

The present paper presents a numerical study on evaporating droplets impinging onto a solid surface through a crossflow. The characteristics of the initial spray are established by employing an empirical procedure that relies on a comprehensive set of free spray measurements. Distinct wall and crossflow temperatures are analyzed systematically to evaluate the influence of droplet evaporation on the final outcome of the simulation and, particularly, on the distribution of the thin liquid film that forms over the surface due to the deposition of incident droplets. The present computational model already has been proven to deliver accurate prediction results of the spray–wall interactions under different conditions. In this work, the conditions are extrapolated to a heated environment, which more adequately reproduces what is found in in-cylinder situations. The computational model is adapted to meet the new requirements and to perform within the range of conditions for which it is now being formulated. The .
Data Analytics for Uncovering Fraudulent Behaviour in Elite Sports

Sports officials around the world are facing societal challenges due to the unfair nature of fraudulent practices performed by unscrupulous athletes. Recently, sample swapping has been raised as a potential practice where some athletes exchange their doped sample with a clean one to evade a positive test. The current detection method for such cases includes laboratory testing like DNA analysis. However, these methods are costly and time-consuming, which goes beyond the budgetary limits of anti-doping organisations. Therefore, there is a need to explore alternative methods to improve decision-making. We presented a data analytical methodology that supports anti-doping decision-makers on the task of athlete disambiguation. Our proposed model helps identify the swapped sample, which outperforms the current state-of-the-art method and different baseline models. The evaluation on real-world sample swapping cases shows promising results that help advance the research on the application of data analytics in the context of anti-doping analysis.
Career Path Clustering via Sequential Job Embedding and Mixture Markov Models

Extracting typical career paths from large­scale and unstructured talent profiles has re­ cently attracted increasing research attention. However, various challenges arise in effec­ tively analyzing self­reported career records. Inspired by recent advances in neural net­ works and embedding models, we develop a novel career path clustering approach with twomajor components. First, we formulate an embeddedMarkov framework to learn job embeddings from longitudinal career records and further use them to compute dynamic embeddings of career paths. Second, to cope with heterogeneous career path clusters, we estimate amixture ofMarkovmodels to optimize cluster­wise job embeddingswith a prior embedded space shared by multiple clusters. We conduct extensive experiments with our framework to investigate its algorithmic performance and extract meaningful patterns of career paths in the information technology (IT) industry. The results show that our ap­ proach can naturally discover distinct career path clusters and reveal valuable insights.
Double-Layered Quad-Band Bandpass Filter for Multi-Band Wireless Systems

A compact double-layered quad-band (DLQB) bandpass filter (BPF) is presented to provide four passbands at the desired frequencies with efficient out-of-band suppression. The designed filter is verified by pattern implementation on two FR4 boards. The proposed DLQB-BPF consists of two L-shaped resonators on the first layer and two symmetrically-coupled stepped-impedance resonators (SIRs) on the second layer. The bottom of the second layer is ground plane. There are seven transmission zeros generated to perform quad-band characteristics at 1.57 GHz, 2.45 GHz, 3.6 GHz, and 5.8 GHz. An equivalent circuit model is constructed by analyzing the symmetry property of the proposed filter. A good agreement between the simulated and measured results is observed.
Stimulus Features in Signal Detection

Short bursts of computer‐generated Gaussian noise were rated by observers for the presence or absence of a 500‐Hz signal tone burst. A multiple regression analysis found for each observer the linear combination of the energies in narrow bands around the tone frequency that best predicts his total ratings. The estimates of the regression coefficients provide graphs of the “frequency responses” of the observers. Most of the reliable variance in the total ratings was accounted for by the regression analysis in terms of energy in narrow bands. Differences among observers are explained in terms of differential weighting by observers of features labeled “tone presence,” “pitch,” and “loudness. ”
A strategy for operational implementation of 4D‐Var, using an incremental approach

SUMMARY An order of magnitude reduction in the cost of fourdimensional variational assimilation (4D-Var) is required before operational implementation is possible. Reconditioning is considered and, although it offers a signi6cant reduction in cost, it seems that it is unlikely to provide a reduction as large as an order of magnitude. An approximation to 4D-Var, namely the incremental approach, is then considered and is shown to produce the same result at the end of the assimilation window as an extended Kalman filter in which no approximations are made in the assimilating model but in which instead a simplitied evolution of the forecast error is introduced. This approach provides the flexibility for a cost-benefit trade-off of 4D-Var to be made. The development of variational four-dimensional assimilation (4D-Var) from the stage of being a theoretical possibility to being a practical reality is progressing at a rapid pace. The first results of four-dimensional variational assimilation using real observations were provided by Thbpaut et al. (1993b) using an adiabatic primitive-equation model at truncations "21 and T42. More recently Andersson ef al. (1994) used 4D-Var with a T63 model to assimilate remotely-sensed data such as infrared and microwave TOVS radiance measurements, while Thdpaut et d. (1993a) used 4D-Var with the same model to assimilate normalized radar backscatter cross-section measurements from the ERS-1 scatterometer.
The relation of line narrowing and chirp reduction resulting from the coupling of a semiconductor laser to passive resonator

We present a theory of adiabatic chirp reduction and narrowing of the Lorentzian laser line that occurs when a laser is coupled to an external passive resonator. Chirp reduction and line narrowing are simply related. We show that the reduction in the Lorentzian line width is equal to the square of the reduction in adiabatic chirp. Both are strongly enhanced near resonances of the external cavity.
Primordial fluctuations and non-linear structure

Several aspects of nonlinear gravitational instability are explored using two numerical experiments, each of which employs a series of 3D cosmological N-body simulations. In the first experiment, all of the initial high-frequency power is truncated above some critical wavenumber, in the second experiment, initial Fourier components are replaced with wavenumbers greater than critical by waves taken from an independent realization with the same power spectrum but with unrelated phases. These initial conditions are evolved for different values of critical wavenumbers to see how the progressive elimination or substitution of initial high-frequency components affects the final, nonlinear structure.
Application of the exact constitutive relationship of modified Cam clay to the undrained expansion of a spherical cavity

The modified Cam clay (MCC) model is used to study the response of virgin‐compressed clay subjected to undrained triaxial compression. The MCC constitutive relationship is obtained in a closed form. Both elastic and plastic deviatoric strains are considered in the analysis. The solution allows to obtain total and effective stress paths followed by the clay in undrained spherical expansion. Pore water pressures are determined from the difference between total and effective mean stresses. For illustration purposes, the analysis is also applied to the well‐known reconstituted normally consolidated London clay and the results are compared with the recently published data obtained by a numerical approach. In addition, the Almansi large strains are used in the analysis, as these allow to obtain limit expansion and pore pressures, whereas both small‐strain and logarithmic‐strain approaches do not permit to determine them. Copyright © 2010 John Wiley & Sons, Ltd.
All-fibre optical sensing system: Bragg grating sensor interrogated by a long-period grating

We report here a simple, low-cost all-fibre grating strain sensing interrogation technique offering high static-strain resolution and large dynamic range . A key interrogating component of this technique is a long-period grating which acts as an edge filter converting strain-induced wavelength variation into optical power measurement. The transmission profile of the long-period grating is shown to be nearly linear over a sufficiently wide range, yielding a linear relationship between the resultant intensity and applied strain, and a high resolution achieved by standard lock-in techniques.
Terahertz time-domain spectroscopy of sulfur-containing biomolecules

We present frequency-dependent absorption coefficients and refractive indices of sulfur-containing biomolecules in the far-infrared region measured by terahertz (THz) time-domain spectroscopy (TDS). The THz radiation was generated by a surface photocurrent method with a (100)InAs wafer as a THz emitter, and its intensity was enhanced by applying a magnetic field of 1.6 T. The THz radiation was detected by the electro-optic sampling method with a ZnTe crystal. The characterization of the apparatus of THz TDS is discussed in detail. The spectral features in the THz region are different among sulfur-containing biomolecules of L,L-cystine, L-cysteine, L-methionine, and oxidized glutathione in powder. These results demonstrate that THz TDS is a promising method for studies on the low-frequency spectra of complex molecules and identification of materials. We present a calculation method to analyze the THz spectra based on a model function for dynamics of the dipoles, which allows us to obtain spectral information characterizing the low-frequency responses of the molecules. The experimental results are compared with ab initio calculations to discuss assignment of the vibrational modes.
An approach to estimate short‐term, long‐term and reaction norm repeatability

Evolutionary ecologists increasingly study reaction norms that are expressed repeatedly within the same individual's lifetime. For example, foragers continuously alter anti‐predator vigilance in response to moment‐to‐moment changes in predation risk. Variation in this form of plasticity occurs both among and within individuals. Among‐individual variation in plasticity (individual by environment interaction or I × E) is commonly studied; by contrast, despite increasing interest in its evolution and ecology, within‐individual variation in phenotypic plasticity is not. We outline a study design based on repeated measures and a multilevel extension of random regression models that enables quantification of variation in reaction norms at different hierarchical levels (such as among and within individuals). The approach enables the calculation of repeatability of reaction norm intercepts (average phenotype) and slopes (level of phenotypic plasticity); these indices are not specific to measurement or scaling and are readily comparable across data sets. The proposed study design also enables calculation of repeatability at different temporal scales (such as short‐ and long‐term repeatability), thereby answering calls for the development of approaches enabling scale‐dependent repeatability calculations. We introduce a simulation package in the R statistical language to assess power, imprecision and bias for multilevel random regression that may be utilised for realistic data sets (unequal sample sizes across individuals, missing data, etc). We apply the idea to a worked example to illustrate its utility. We conclude that consideration of multilevel variation in reaction norms deepens our understanding of the hierarchical structuring of labile characters and helps reveal the biology in heterogeneous patterns of within‐individual variance that would otherwise remain ‘unexplained’ residual variance.
Role of the Dilatonic potential to the Quantum stabilization of dilatonic Anti-de Sitter Universe

Quantum effects lead to the annihilation of AdS Universe when dilaton is absent. We consider here the role of the form for the dilatonic potential in the quantum creation of a dilatonic AdS Universe and its stabilization. Using the conformal anomaly for dilaton coupled scalar, the anomaly induced action and the equations of motion are obtained. Using numerical methods the solutions of the full theory which correspond to quantum-corrected AdS Universe are given for a particular case of dilatonic potential.
Refining virtual knot invariants by means of parity

In this work two new invariants of virtual links are constructed: the even Alexander polynomial and the even quandle. The general idea behind the construction is to split the classical crossings into two types, the even and the odd ones, and then define different operations at the crossings of different types. On the other hand, the proposed construction is a realization of the same idea using two closely related languages: the language of quandles and the language of Alexander polynomials. Bibliography: 15 titles.
Optimal finite difference grids and rational approximations of the square root I. Elliptic problems

The main objective of this paper is optimization of second-order finite difference schemes for elliptic equations, in particular, for equations with singular solutions and exterior problems. A model problem corresponding to the Laplace equation on a semi-infinite strip is considered. The boundary impedance (Neumann-to-Dirichlet map) is computed as the square root of an operator using the standard three-point finite difference scheme with optimally chosen variable steps. The finite difference approximation of the boundary impedance for data of given smoothness is the problem of rational approximation of the square root on the operator's spectrum. We have implemented Zolotarev's optimal rational approx-imant obtained in terms of elliptic functions. We have also found that a geometrical progression of the grid steps with optimally chosen parameters is almost as good as the optimal approximant. For bounded operators it increases from second to exponential the convergence order of the finite difference impedance with the convergence rate proportional to the inverse of the logarithm of the condition number. For the case of unbounded operators in Sobolev spaces associated with elliptic equations, the error decays as the exponential of the square root of the mesh dimension. As an example, we numerically compute the Green function on the boundary for the Laplace equation. Some features of the optimal grid obtained for the Laplace equation remain valid for more general elliptic problems with variable coefficients. © 2000 John Wiley & Sons, Inc.
VERTICAL PROFILE OF RADIO REFRACTIVITY GRADIENT IN AKURE SOUTH-WEST NIGERIA.

In the planning and design of microwave communication links, the structure of the radio refractive index in the lower part of the atmospheric boundary layer is very important. In this work, measurements of atmospheric pressure, temperature and relative humidity were made in Akure (7.15 ◦ N, 5.12 ◦ E), South Western Nigeria. Wireless weather stations (Integrated Sensor Suite, ISS) were'positioned at five different height levels beginning from the ground surface and at intervals of 50 m from the ground to a height of 200 m (0, 50, 100, 150 and 200 m) on a 220 m Nigeria Television Authority TV tower at Iju in Akure North Local Government area of Ondo State. The measurement of the atmospheric variables was made every 30 minutes everyday. The study utilized the data for the first year of measurement (January-December 2007) to compute the radio refractivity and its refractivity gradient in Akure. From these parameters, the vertical distributions of radio refractivity are then determined. The results obtained show that the propagation conditions have varying degree of occurrence with sub-refractive conditions observed to be prevalent between January-July while Super-refraction and Ducting were observed mostly between August-December.
Simulation of silicon clusters and surfaces via tight-binding molecular dynamics.

A prescription is developed which incorporates the tight-binding total energy for silicon into the molecular-dynamics scheme of dynamical simulated annealing first proposed by Car and Parrinello (Phys. Rev. Lett. 55, 2471 (1985)). The total-energy expression of Tomanek and Schlueter (Phys. Rev. Lett. 56, 1055 (1986); Phys. Rev. B 36, 1208 (1987)) with appropriate cutoff functions to permit molecular-dynamics simulations is used to calculate the forces on the ions and the electronic degrees of freedom. A self-contained description of the total-energy expression and the simulation method is presented. The scheme permits efficient quenching to zero-temperature and finite-temperature simulations of silicon clusters and surfaces. This method can perform realistic simulations on large systems of the order of hundreds of atoms with time requirements of the order of tens of Cray XMP/24 central-processing-unit hours. The prescription is tested and benchmarked on ground-state geometries of the Si/sub 3/ cluster and the reconstruction of the Si(100) surface.
Changes of the mean velocity profiles in the combined wave–current motion described in a GLM formulation

The generalized Lagrangian mean (GLM) formulation is used to describe the interaction of waves and currents. In contrast to the more conventional Eulerian formulation the GLM description enables splitting of the mean and oscillating motion over the whole depth in an unambiguous and unique way, also in the region between wave crest and trough. The present paper deals with non-breaking long-crested regular waves on a current using the GLM formulation coupled with a WKBJ-type perturbation-series approach. The waves propagate under an arbitrary angle with the current direction. The primary interest concerns nonlinear changes in the vertical distribution of the mean velocity due to the presence of the waves, but modifications of the orbital velocity profiles, due to the presence of a current, are considered as well. The special case of no initial current, where waves induce a so-called drift velocity or mass-transport velocity, is also studied.
Two-dimensional wave-vector correlations in spontaneous parametric downconversion explored with an intensified CCD camera

Utilizing a new scheme with a single-photon-sensitive intensified CCD camera and a femtosecond laser, we have measured signal–idler correlations over the full cone of degenerate type I spontaneous parametric downconversion, thereby establishing wave-vector correlations in two dimensions. We discuss the key features of the camera that are important for its use in twin-photon correlation measurements.
3D microscope using diffraction grating

An optical microscope has been adapted for 3-D inspection of small capillaries in thread spinnerets by placing a diffraction grating between the microscope objective and the specimen. We show how a grating was specified using a quantitative analysis of groove spacing and geometry. An illumination system was specified based on incident angle and light wavelength. Specimens are placed on a robotic stage for positioning, and repositioning affords multiple perspective views of the target depending upon the diffraction order visible to the objective.
Collision Detection Based on Surface Simplification and Particle Swam Optimization

We present an efficient stochastic collision detection based on surface simplification and particle swam optimization (PSO). In this framework, first, the search space is reduced by surface simplification during the pre-process and then the interference triangles are gained by PSO. This framework takes the surface simplification’s advantage of decreasing the triangles dramatically with little geometry error. In order to handle every collision detection step, we use surface simplification and PSO, by which user not only can balance performance and detection quality, but also increase the speed of collision detection.
Design of vector autoregressive processes for invariant statistics

This paper discusses the Monte Carlo (MC) design of Gaussian Vector Au- toregressive processes (VAR) for the evalutation of invariant statistics. We focus on the case of cointegrated (CI) I(1) processes, linear and invertible trans- formations and CI rank likelihood ratio (LR) tests. It is found that all VAR of order 1 can be reduced to a system of independent or recursive subsystems, of computational dimension at most equal to 2. The results are applied to the indexing of the distribution of LR test statistics for CI rank under local alternatives. They are also extended to the case of VAR processes of higher order.