Miracle-dz/UniFAR-FTUs huggingface dataset:
Einstein manifolds of dimension five with small first eigenvalue of the Dirac operator

Soit M n une variete de spin compacte d'Einstein a courbure scalaire positive R>0 et on note par D: T(S)→T(S) l'operateur de Dirac agissant sur des sections du fibre spinoriel. On etudie le probleme de la classification des varietes pour le cas a 5 dimensions
Multipartite interacting scalar dark matter in the light of updated LUX data

We explore constraints on multipartite dark matter (DM) framework composed of singlet scalar DM interacting with the Standard Model (SM) through Higgs portal coupling. We compute relic density and direct search constraints including the updated LUX bound for two component scenario with non-zero interactions between two DM components in 𝒵2 × 𝒵2′ framework in comparison with the one having 𝒪(2) symmetry. We point out availability of a significantly large region of parameter space of such a multipartite model with DM-DM interactions.
Acoustic Models for Posterior Features in Speech Recognition

In this thesis, we investigate the use of posterior probabilities of sub-word units directly as input features for automatic speech recognition (ASR). These posteriors, estimated from data-driven methods, display some favourable properties such as increased speaker invariance, but unlike conventional speech features also hold some peculiarities, such that their components are non-negative and sum up to one. State-of-the-art acoustic models for ASR rely on general-purpose similarity measures like Euclidean-based distances or likelihoods computed from Gaussian mixture models (GMMs), hence, they do not explicitly take into account the particular properties of posterior-based speech features. We explore here the use of the Kullback-Leibler (KL) divergence as similarity measure in both non-parametric methods using templates and parametric models that rely on an architecture based on hidden Markov models (HMMs). Traditionally, template matching (TM)-based ASR uses cepstral features and requires a large number of templates to capture the natural variability of spoken language. Thus, TM-based approaches are generally oriented to speaker-dependent and small vocabulary recognition tasks. In our work, we use posterior features to represent the templates and test utterances. Given the discriminative nature of posterior features, we show that a limited number of templates can accurately characterize a word. Experiments on different databases show that using KL divergence as local similarity measure yields significantly better performance than traditional TM-based approaches. The entropy of posterior features can also be used to further improve the results. In the context of HMMs, we propose a novel acoustic model where each state is parameterized by a reference multinomial distribution and the state score is based on the KL divergence between the reference distribution and the posterior features. Besides the fact that the KL divergence is a natural dissimilarity measure between posterior distributions, we further motivate the use of the KL divergence by showing that the proposed model can be interpreted in terms of maximum likelihood and information theoretic clustering. Furthermore, the KL-based acoustic model can be seen as a general case of other known acoustic models for posterior features such as hybrid HMM/MLP and discrete HMM. The presented approach has been extended to large vocabulary recognition tasks. When compared to state-of-the-art HMM/GMM, the KL-based acoustic model yields comparable results while using significantly fewer parameters.
Continuity of functions belonging to the fractional order Sobolev-Grand Lebesgue Spaces

We extend in this article the classical Sobolev inequalities for the module of continuity for the functions belonging to the integer order Sobolev's space on the Sobolev-Bilateral Grand Lebesgue spaces. As a consequence, we deduce the fractional Orlicz-Sobolev imbedding theorems and investigate the rectangle module of continuity of non-Gaussian multiparameter random fields.
Idealized hydrodynamic simulations of turbulent oxygen-burning shell convection in 4π geometry

This work investigates the properties of convection in stars with particular emphasis on entrainment across the upper convective boundary (CB). Idealised simulations of turbulent convection in the O-burning shell of a massive star are performed in $4\pi$ geometry on $768^3$ and $1536^3$ grids, driven by a representative heating rate. A heating series is also performed on the $768^3$ grid. The $1536^3$ simulation exhibits an entrainment rate at the upper CB of $1.33\times10^{-6}~M_\odot~\mathrm{s}^{-1}$. The $768^3$ simulation with the same heating rate agrees within 17 per cent. The entrainment rate at the upper convective boundary is found to scale linearly with the driving luminosity and with the cube of the shear velocity at the upper boundary, while the radial RMS fluid velocity scales with the cube root of the driving luminosity, as expected. The mixing is analysed in a 1D diffusion framework, resulting in a simple model for CB mixing. The analysis confirms previous findings that limiting the MLT mixing length to the distance to the CB in 1D simulations better represents the spherically-averaged radial velocity profiles from the 3D simulations and provides an improved determination of the reference diffusion coefficient $D_0$ for the exponential diffusion CB mixing model in 1D. From the 3D simulation data we adopt as the convective boundary the location of the maximum gradient in the horizontal velocity component which has $2\sigma$ spatial fluctuations of $\approx0.17 H_P$ . The exponentially decaying diffusion CB mixing model with $f = 0.03$ reproduces the spherically-averaged 3D abundance profiles.
Large-Eddy Simulation Analysis of Unsteady Separation Over a Pitching Airfoil at High Reynolds Number

Abstract : Unsteady flow separation during dynamic stall often leads to unacceptably large vibratory loads and acoustic noise, and limit forward flight speeds and maneuverability. To gain a quantitative understanding of the unsteady separation process, large-eddy simulation (LES) of turbulent flow over a pitching airfoil at realistic Reynolds and Mach numbers is performed. Numerical stability at high Reynolds number simulation is maintained using an unstructured-grid LES technology, which obeys higher-order conservation principles and employs a global-coefficient subgrid-scale turbulence model. A hybrid implicit-explicit time-integration scheme is employed to provide a highly efficient way to treat time-step size restriction in the separated flow region locally refined with dense mesh. The present simulations confirm the stability and effectiveness of the presented numerical schemes for dynamic stall simulations at realistic operating Reynolds and Mach numbers and show the characteristics of flow separation and reattachment processes which are qualitatively congruent with experimental observation. To improve quantitative understanding of unsteady separation processes of turbulent boundary layers, direct numerical simulations are performed. The distinct characteristics of unsteady separating turbulent boundary layers are revealed by a systematic comparison with steady attached/separated turbulent boundary layers. For this purpose, four different flow configurations are simulated: (1) turbulent boundary layer flow with a zero-pressure gradient; (2) turbulent boundary layer flow with an adverse-pressure gradient; (3) steady separated turbulent boundary layer flow; and (4) unsteady separating turbulent boundary layer flow. The present comparative study suggests physical phenomena during the unsteady separation process including unsteady boundary-layer detachment and reattachment, and production and dissipation of turbulent kinetic energy and vorticity.
Holder continuity results for a class of functionals with non standard growth

We prove regularity results for minimizers of the integral functional f(x,u,Du)dx under non-standard growth condotions of p(x)-type, i.e. L-1|x| p(x) ≤ f(x,s,z) ≤ L (1+|x| p(x)) under sharp assumptions on the continuuus function p(x)>1
Variable Stars and The Asymptotic Giant Branch: Stellar Pulsations, Dust Production and Mass Loss

Low and intermediate-mass stars (1–8 M Ä ; LIMS) are very important contributors of material to the interstellar medium (ISM), and yet the mechanisms by which this matter is expelled remain a mystery. In this paper we discuss how interferometry plays a role in studying the interplay between pulsation, mass loss, dust formation and evolution of these LIMS.
DIFFUSION OF MAGNETIC FIELD AND REMOVAL OF MAGNETIC FLUX FROM CLOUDS VIA TURBULENT RECONNECTION

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding fast magnetic reconnection in the presence of turbulence reassures that the magnetic field behavior in computer simulations and turbulent astrophysical environments is similar, as far as magnetic reconnection is concerned. This makes it meaningful to perform MHD simulations of turbulent flows in order to understand the diffusion of magnetic field in astrophysical environments. Our studies of magnetic field diffusion in turbulent medium reveal interesting new phenomena. First of all, our three-dimensional MHD simulations initiated with anti-correlating magnetic field and gaseous density exhibit at later times a de-correlation of the magnetic field and density, which corresponds well to the observations of the interstellar media. While earlier studies stressed the role of either ambipolar diffusion or time-dependent turbulent fluctuations for de-correlating magnetic field and density, we get the effect of permanent de-correlation with one fluid code, i.e., without invoking ambipolar diffusion. In addition, in the presence of gravity and turbulence, our three-dimensional simulations show the decrease of the magnetic flux-to-mass ratio as the gaseous density at the center of the gravitational potential increases. We observe this effect both in the situations when we start with equilibrium distributions of gas and magnetic field and when we follow the evolution of collapsing dynamically unstable configurations. Thus, the process of turbulent magnetic field removal should be applicable both to quasi-static subcritical molecular clouds and cores and violently collapsing supercritical entities. The increase of the gravitational potential as well as the magnetization of the gas increases the segregation of the mass and magnetic flux in the saturated final state of the simulations, supporting the notion that the reconnection-enabled diffusivity relaxes the magnetic field + gas system in the gravitational field to its minimal energy state. This effect is expected to play an important role in star formation, from its initial stages of concentrating interstellar gas to the final stages of the accretion to the forming protostar. In addition, we benchmark our codes by studying the heat transfer in magnetized compressible fluids and confirm the high rates of turbulent advection of heat obtained in an earlier study.
On the variance of sums of divisor functions in short intervals

Given a positive integer $n$ the $k$-fold divisor function $d_k(n)$ equals the number of ordered $k$-tuples of positive integers whose product equals $n$. In this article we study the variance of sums of $d_k(n)$ in short intervals and establish asymptotic formulas for the variance of sums of $d_k(n)$ in short intervals of certain lengths for $k=3$ and for $k \ge 4$ under the assumption of the Lindel\"of hypothesis.
The art of smooth pasting

This book aims to widen the understanding of stochastic dynamic choice and equilibrium models. It offers a simplified and heuristic exposition of the theory of Brownian motion and its control or regulation, rendering such methods more accessible to economists who do not require a detailed, mathematical treatment of the subject. The main mathematical ideas are presented in a context which with which economists will be familiar. Using a binomial approach to Brownian motion, the mathematics is reduced to simple algebra, progressing to some equally simple limits. The starting point of the calculus of Brownian motion - 'Ito's Lemma' - emerges by analogy with the economics of risk-aversion. Conditions for the optimal regulation of Brownian motion, including the important, but often mysterious, 'smooth pasting' condition, are derived in a similar way. Each theoretical derivation is illustrated by developing a significant economic application, drawn mainly from recent research in macroeconomics and international economics.
Numerical Prediction of Turbulent Oscillating Flow and Heat Transfer in Pipes with Various End Geometries. Ph.D. Thesis, Final Report

Unsteady flow is present in man, machine and nature. The flow of blood in arteries and capillaries in the human body is pulsatile-composed of a mean flow superposed with an oscillating component. The tides that wash in and out of rivers, harbors and estuaries are unsteady flows with very long periods of oscillation. Many engineering devices employ pulsatile and oscillating flow. Pulsating flow is defined here as a periodic flow with a net displacement of fluid over each flow cycle. Oscillating flow is defined as a period flow with a zero mean over each cycle. The subject of this thesis is oscillating flow and heat transfer in pipes which make up the heater and cooler sections of the NASA Space Power Research Engine (SPRE) currently under development. This engine uses the Stirling cycle as the thermal energy converter in a power plant for future space applications. The information presented in this thesis will of course be applicable to the design of many types of machinery which employ oscillating flow and heat transfer.
Primate Inferotemporal Cortex Neurons Generalize Better to Novel Image Distributions Than Analogous Deep Neural Networks Units

Humans are successfully able to recognize objects in a variety of image distri- 1 butions. Today’s artificial neural networks (ANNs), on the other hand, struggle 2 to recognize objects in many image domains, especially those different from the 3 training distribution. It is currently unclear which parts of the ANNs could be 4 improved in order to close this generalization gap. In this work, we used recordings 5 from primate high-level visual cortex (IT) to isolate whether ANNs lag behind pri- 6 mate generalization capabilities because of their encoder (transformations up to the 7 penultimate layer), or their decoder (linear transformation into class labels). Specif- 8 ically, we fit a linear decoder on images from one domain and evaluate transfer 9 performance on twelve held-out domains, comparing fitting on primate IT repre- 10 sentations vs. representations in ANN penultimate layers. To fairly compare, we 11 scale the number of each ANN’s units so that its in-domain performance matches 12 that of the sampled IT population (i.e. 71 IT neural sites, 73% binary-choice 13 accuracy). We find that the sampled primate population achieves, on average, 68% 14 performance on the held-out-domains. Comparably sampled populations from 15 ANN model units generalize less well, maintaining on average 60%. These results 16 are independent of the number of sampled units: models’ out-of-domain accuracies 17 consistently lag behind primate IT. These results suggest that making ANN model 18 units more like primate IT will improve the generalization performance of ANNs. 19
Large-scale motions in the universe : a Vatican study week

This book brings together the thinking of twenty-two eminent astronomers on a fascinating topic of contemporary astrophysics: large-scale galaxy motions. Stars group into galaxies, galaxies unite into clusters, clusters merge into superclusters, and superclusters meet at intersections of filaments to define voids and supercluster complexes. Can gravity alone, arising from this irregular mass distribution, produce the motions which observers detect? In this collection, astronomers discuss evidence for irregular clumping of galaxies throughout the observed universe, determination of galaxy peculiar motions, and predictions from theories of the early universe relating to small-scale fluctuations in the microwave background radiation, the lumpy matter distribution, and large motions. This book can serve as a companion volume to The Large-Scale Structure of the Universe by P.J.E. Peebles (Princeton, 1980). Authors of chapters in the book include N. A. Bahcall, J. R. Bond, D. Burstein, M. Davis, A. Dekel, G. Efstathiou, S. M. Faber, M. Geller, M. P. Haynes, J. P. Huchra, N. Kaiser, D. C. Koo, A. N. Lasenby, D. Lynden-Bell, J. Mould, P.J.E. Peebles, V. C. Rubin, A. Szalay, R. B. Tully, N. Vittorio, and A. Yahil.
Absolute luminosity measurements with the LHCb detector at the LHC

Absolute luminosity measurements are of general interest for colliding-beam experiments at storage rings. These measurements are necessary to determine the absolute cross-sections of reaction processes and are valuable to quantify the performance of the accelerator. LHCb has applied two methods to determine the absolute scale of its luminosity measurements for proton-proton collisions at the LHC with a centre-of-mass energy of 7 TeV. In addition to the classic "van der Meer scan" method a novel technique has been developed which makes use of direct imaging of the individual beams using beam-gas and beam-beam interactions. This beam imaging method is made possible by the high resolution of the LHCb vertex detector and the close proximity of the detector to the beams, and allows beam parameters such as positions, angles and widths to be determined. The results of the two methods have comparable precision and are in good agreement. Combining the two methods, an overal precision of 3.5% in the absolute luminosity determination is reached. The techniques used to transport the absolute luminosity calibration to the full data-taking period are presented.
Bad Science: Retractions and Media Coverage

Flawed research can be harmful both within and outside of academia. Even when scientific work has been retracted and refuted by the scientific community, it may continue to be a source of misinformation. The media can play an important role in drawing broader attention to research, but may equally ensure that research, once retracted, ceases to feature in popular discourse. Yet, there is little evidence on whether media reporting influences the retraction process and authors’ careers. Using a conditional difference-in-differences strategy, this paper shows that articles that gained popularity in the media at publication and were later retracted face heavy citation losses, while subsequent citations become more accurate. Further, authors of such papers see a permanent decline in research output. Lastly, the paper provides evidence that media can influence both the likelihood of retraction and its timing, highlighting that the media can play an important role in contributing to the integrity of the research process.
Acute unilateral vestibular neuritis contributes to alterations in vestibular function modulating circumvention around obstacles: A pilot study suggesting a role for vestibular signals in the spatial perception of orientation during circumvention

Background Walking among crowds avoiding colliding with people is described by patients with vestibular disorders as vertigo-inducing. Accurate body motion while circumventing an impeding obstacle in the gait pathway is dependent on an integration of multimodal sensory cues. However, a direct role of vestibular signals in spatial perception of distance or orientation during obstacle circumvention has not been investigated to date. Materials and methods We examined trunk yaw motion during circumvention in patients with acute unilateral vestibular loss (aUVL) and compared their results with age-matched healthy controls (HCs). Subjects performed five gait tasks with eyes open two times: walk 6 m in total, but after 3 m, circumvent to the left or right, as closely as possible, a cylindrical obstacle representing a person, and then veer back to the original path; walk 6 m, but after left and right circumvention at 3 m, veer, respectively, to the right, and left 45 deg; and walk 6 m without circumvention. Trunk yaw angular velocities (YAVs) were measured using a gyroscope system. Results Yaw angular velocity peak amplitudes approaching to, and departing from, the circumvented object were always greater for patients with aUVL compared to HCs, regardless of whether passing was to the aUVLs’ deficit or normal side. The departing peak YAV was always greater, circa 52 and 87%, than the approaching YAV for HCs when going straight and veering 45 deg (p ≤ 0.0006), respectively. For patients with aUVL, departing velocities were marginally greater (12%) than approaching YAVs when going straight (p < 0.05) and were only 40% greater when veering 45 deg (p = 0.05). The differences in departing YAVs resulted in significantly lower trajectory-end yaw angles for veering trials to the deficit side in patients with aUVL (34 vs. 43 degs in HCs). Conclusion The results demonstrate the effects of vestibular loss on yaw velocity control during the three phases of circumvention. First, approaching an obstacle, a greater YAV is found in patients with aUVL. Second, the departing YAV is found to be less than in HCs with respect to the approaching velocity, resulting in larger deficit side passing yaw angles. Third, patients with UVLs show yaw errors returning to the desired trajectory. These results could provide a basis for rehabilitation protocols helping to avoid collisions while walking in crowded spaces.
Acceleration of primary and secondary particles in galaxy clusters by compressible MHD turbulence: from radio haloes to gamma-rays

Radio observations discovered large-scale non-thermal sources in the central Mpc regions of dynamically disturbed galaxy clusters (radio haloes). The morphological and spectral properties of these sources suggest that the emitting electrons are accelerated by spatially distributed and gentle mechanisms, providing some indirect evidence for turbulent acceleration in the intergalactic medium (IGM). Only deep upper limits to the energy associated with relativistic protons in the IGM have been recently obtained through gamma and radio observations. Yet these protons should be (theoretically) the main non-thermal particle component in the IGM implying the unavoidable production, at some level, of secondary particles that may have a deep impact on the gamma-ray and radio properties of galaxy clusters. Following Brunetti & Lazarian, in this paper we consider the advances in the theory of magnetohydrodynamics (MHD) turbulence to develop a comprehensive picture of turbulence in the IGM and extend our previous calculations of particle acceleration by compressible MHD turbulence by considering self-consistently the re-acceleration of both primary and secondary particles. Under these conditions we expect that radio to gamma-ray emission is generated from galaxy clusters with a complex spectrum that depends on the dynamics of the thermal gas and dark matter. The non-thermal emission results in very good agreement with radio observations and with present constraints from hard X-ray and gamma-ray observations. In our model giant radio haloes are generated in merging (turbulent) clusters only. However, in case secondaries dominate the electron component in the IGM, we expect that the level of the Mpc-scale synchrotron emission in more relaxed clusters is already close to that of the radio upper limits derived by present observations of clusters without radio haloes. Important constraints on cluster physics from future observations with present and future telescopes are also discussed.